This file contains information about GCC releases which has been generated

This file contains information about GCC releases which has been generated
automatically from the online release notes. It covers releases of GCC
(and the former EGCS project) since EGCS 1.0, on the line of development
that led to GCC 3. For information on GCC 2.8.1 and older releases of GCC 2,
see ONEWS.

======================================================================
http://gcc.gnu.org/gcc-12/index.html

GCC 12 Release Series

July 11, 2025

The GCC developers are pleased to announce the release of GCC 12.5.

This release is a bug-fix release, containing fixes for regressions in
GCC 12.4 relative to previous releases of GCC.

Release History

GCC 12.5
July 11, 2025 ([1]changes, [2]documentation)

GCC 12.4
Jun 20, 2024 ([3]changes, [4]documentation)

GCC 12.3
May 8, 2023 ([5]changes, [6]documentation)

GCC 12.2
Aug 19, 2022 ([7]changes, [8]documentation)

GCC 12.1
May 6, 2022 ([9]changes, [10]documentation)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [11]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [12]GCC
project web site or contact the [13]GCC development mailing list.

To obtain GCC please use [14]our mirror sites or [15]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [16]GCC manuals. If that fails, the
[17][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [18][email protected]. All of [19]our lists have public
archives.

Copyright (C) [20]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [21]maintained by the GCC team. Last modified
2025-07-11.

References

1. https://gcc.gnu.org/gcc-12/changes.html
2. https://gcc.gnu.org/onlinedocs/12.5.0/
3. https://gcc.gnu.org/gcc-12/changes.html
4. https://gcc.gnu.org/onlinedocs/12.4.0/
5. https://gcc.gnu.org/gcc-12/changes.html
6. https://gcc.gnu.org/onlinedocs/12.3.0/
7. https://gcc.gnu.org/gcc-12/changes.html
8. https://gcc.gnu.org/onlinedocs/12.2.0/
9. https://gcc.gnu.org/gcc-12/changes.html
10. https://gcc.gnu.org/onlinedocs/12.1.0/
11. https://gcc.gnu.org/onlinedocs/gcc-12.1.0/gcc/Contributors.html
12. https://gcc.gnu.org/index.html
13. mailto:[email protected]
14. https://gcc.gnu.org/mirrors.html
15. https://gcc.gnu.org/git.html
16. https://gcc.gnu.org/onlinedocs/
17. mailto:[email protected]
18. mailto:[email protected]
19. https://gcc.gnu.org/lists.html
20. https://www.fsf.org/
21. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-12/changes.html

GCC 12 Release Series
Changes, New Features, and Fixes

This page is a "brief" summary of some of the huge number of
improvements in GCC 12. You may also want to check out our [1]Porting
to GCC 12 page and the [2]full GCC documentation.

Caveats

* An ABI incompatibility between C and C++ when passing or returning
by value certain aggregates containing zero width bit-fields has
been discovered on various targets. As mentioned in [3]PR102024,
since the [4]PR42217 fix in GCC 4.5 the C++ front-end has been
removing zero width bit-fields from the internal representation of
the aggregates after the layout of those aggregates, but the C
front-end kept them, so passing e.g. struct S { float a; int : 0;
float b; } or struct T { float c; int : 0; } by value could differ
between C and C++. Starting with GCC 12 the C++ front-end no longer
removes those bit-fields from the internal representation and per
clarified psABI some targets have been changed, so that they either
ignore those bit-fields in the argument passing by value decisions
in both C and C++, or they always take them into account. x86-64,
ARM and AArch64 will always ignore them (so there is a C ABI
incompatibility between GCC 11 and earlier with GCC 12 or later),
PowerPC64 ELFv2 and S/390 always take them into account (so there
is a C++ ABI incompatibility, GCC 4.4 and earlier compatible with
GCC 12 or later, incompatible with GCC 4.5 through GCC 11). RISC-V
has changed the handling of these already starting with GCC 10. As
the ABI requires, MIPS takes them into account handling function
return values so there is a C++ ABI incompatibility with GCC 4.5
through 11. For function arguments on MIPS, refer to [5]the MIPS
specific entry. GCC 12 on the above targets will report such
incompatibilities as warnings or other diagnostics unless
-Wno-psabi is used.
* C: Computed gotos require a pointer type now.
* C++: Two non-standard std::pair constructors have been deprecated.
These allowed the use of an rvalue and a literal 0 to construct a
pair containing a move-only type and a pointer. The nullptr keyword
should be used to initialize the pointer member instead of a
literal 0, as this is portable to other C++ implementations.
* The configuration option --enable-libstdcxx-allocator no longer
supports the bitmap, mt, and pool arguments. Those configurations
had been broken for some time.
* D: Building and bootstrapping GDC, the D compiler, now requires a
working GDC (GCC version 9.1 or later) and D runtime library,
libphobos, as the D front end is written in D. On some targets,
libphobos isn't enabled by default, but compiles and works if
--enable-libphobos is used. Other targets may require a more recent
version of GCC to bootstrap. Specifics are documented for affected
targets in the [6]Installing GCC manual.
* Fortran: OpenMP code using the omp_lib.h include file can no longer
be compiled with -std=f95 but now requires at least -std=f2003.
Alternatively, use the omp_lib module, which still supports
-std=f95 and is recommended to be used instead in general.
* OpenMP offloading to Intel MIC has been deprecated and will be
removed in a future release.
* The cr16 target with the cr16-*-* configuration has been obsoleted
and will be removed in a future release.
* The hppa[12]*-*-hpux10* and hppa[12]*-*-hpux11* configurations
targeting 32-bit PA-RISC with HP-UX have been obsoleted and will be
removed in a future release.
* The m32c*-*-rtems* configuration has been obsoleted and will be
removed in a future release.
* The support for the m32r-*-linux*, m32rle-*-linux*,
m68k*-*-openbsd* and vax-*-openbsd* configurations has been
removed.
* STABS: Support for emitting the STABS debugging format is
deprecated and will be removed in the next release. All ports now
default to emit DWARF (version 2 or later) debugging info or are
obsoleted.
* The optimization level -Ofast now implies
-fno-semantic-interposition.

[7]General Improvements

* Vectorization is enabled at -O2 which is now equivalent to what
would have been -O2 -ftree-vectorize -fvect-cost-model=very-cheap
in the past. Note that the default vectorizer cost model has been
changed; it used to behave as if -fvect-cost-model=cheap had been
specified.
* GCC now supports the [8]ShadowCallStack sanitizer, which can be
enabled using the command-line option
[9]-fsanitize=shadow-call-stack. This sanitizer currently only
works on AArch64 targets and it requires an environment in which
all code has been compiled with -ffixed-r18. Its primary initial
user is the Linux kernel.

[10]New Languages and Language specific improvements

* OpenMP
+ OpenMP 5.0 support has been extended: The close map modifier
and the affinity clause are now supported. In addition,
Fortran gained the following features which were available in
C and C++ before: declare variant is now available, depobj,
mutexinoutset and iterator can now also be used with the
depend clause, defaultmap has been updated for OpenMP 5.0, and
the loop directive and combined directives involving the
master directive have been added.
+ The following OpenMP 5.1 features have been added: support for
expressing OpenMP directives as C++ 11 attributes, the masked
and scope constructs, the nothing and error directives, and
using primary with the proc_bind clause and OMP_PROC_BIND
environment variable, the reproducible and unconstrained
modifiers to the order clause, and, for C/C++ only, the align
and allocator modifiers to the allocate clause and the atomic
extensions are now available. The OMP_PLACE environment
variable supports the OpenMP 5.1 features. In addition, the
OMP_NUM_TEAMS and OMP_TEAMS_THREAD_LIMIT environment variables
and their associated API routines are now supported as well as
the memory-allocation routines added for Fortran and extended
for C/C++ in OpenMP 5.1. In Fortran code, strictly structured
blocks can be used.
+ The [11]OpenMP Implementation Status can be found in the
libgomp manual.
* Version 2.6 of the [12]OpenACC specification continues to be
maintained and improved in the C, C++ and Fortran compilers. See
the [13]implementation status section on the OpenACC wiki page and
the [14]run-time library documentation for further information. In
addition to general performance tuning and bug fixing, new features
include:
+ OpenACC worker parallelism for [15]AMD GPUs (already for a
long time supported for [16]Nvidia GPUs).
+ Data privatization/sharing at the OpenACC gang level.
+ Considerable improvements for the experimental OpenACC
'kernels' decomposition ([17]--param
openacc-kernels=decompose).
+ A new warning flag [18]-Wopenacc-parallelism to warn about
potentially suboptimal choices related to OpenACC parallelism.
* The offload target code generation for OpenMP and OpenACC can now
be better adjusted using the new [19]-foffload-options= flag and
the pre-existing but now documented [20]-foffload= flag.

[21]Ada

* Ada 2022
+ Added the -gnat2022 flag to indicate strict Ada 2022
compliance. The old -gnat2020 flag is now deprecated.
+ Support for Big Numbers (Annex G) has seen continuous
improvements. It is now considered complete. It is compatible
with SPARK, i.e. can be used from SPARK code.
+ Continuous improvements to the Ada 2022 standard since GCC 11.
+ Greatly improved compile time support. More functions can now
have the with Static aspect and can be used in more contexts.
* Ada 2022 extensions. The use of the -gnatX flag is necessary to
access these features as they are not considered stable or
standard.
+ Fixed lower bound for unconstrained arrays.
o type Matrix is array (Natural range 0 .. <>, Natural
range 0 .. <>) of Integer; is now valid.
o Subtypes can also specify a lower bound: subtype String_1
is String (1 .. <>);. Boundaries from slices will "slide"
to the correct lower bound of the subtype.
+ Generalized Object.Operand notation. The following code is now
valid V.Add_Element(42);, with V being a vector, for example.
+ Additional when constructs. Keywords return, goto and raise
can now use when in addition to the existing exit when. The
following expression is therefore now valid raise
Constraint_Error with "Element is null" when Element = null;
+ Pattern matching
o The case statement has been extended to cover records and
arrays as well as finer grained casing on scalar types.
In the future it is expected to provide more compile time
guarantees when accessing discriminated fields. Case
exhaustion is supported for pattern matching. An example
would be
type Sign is (Neg, Zero, Pos);

function Multiply (S1, S2 : Sign) return Sign is
(case (S1, S2) is
when (Neg, Neg) | (Pos, Pos) => Pos,
when (Zero, <>) | (<>, Zero) => Zero,
when (Neg, Pos) | (Pos, Neg) => Neg);

* gnatfind and gnatxref, which were already deprecated, have been
removed.
* Greatly expanded code covered by contracts. Thanks to this work,
there are now several Ada standard libraries fully proven in SPARK
which means they have no runtime nor logical errors. They are
mostly numeric and string handling libraries.
* Enable return-slot optimization for Pure functions.
* General optimizations, improvements and additions to the standard
library. Performance, correctness and in some cases stability was
improved. Memory pools have also seen some minor enhancements.
* Improvements to embedded-RTOS targets such as RTEMS, VxWorks and
QNX. Older targets were removed or cleaned.
* Added some [22]hardening features.

[23]C family

* Support for __builtin_shufflevector compatible with the clang
language extension was added.
* Support for attribute unavailable was added.
* A new built-in function, __builtin_assoc_barrier, was added. It can
be used to inhibit re-association of floating-point expressions.
* Support for __builtin_dynamic_object_size compatible with the clang
language extension was added.
* New warnings:
+ [24]-Wbidi-chars warns about potentially misleading UTF-8
bidirectional control characters. The default is
-Wbidi-chars=unpaired ([25]PR103026)
+ [26]-Warray-compare warns about comparisons between two
operands of array type ([27]PR97573)
* Enhancements to existing warnings:
+ [28]-Wattributes has been extended so that it's possible to
use -Wno-attributes=ns::attr or -Wno-attributes=ns:: to
suppress warnings about unknown scoped attributes (in C++11
and C2X). Similarly, #pragma GCC diagnostic ignored_attributes
"vendor::attr" can be used to achieve the same effect
([29]PR101940)

[30]C

* Some new features from the upcoming C2X revision of the ISO C
standard are supported with -std=c2x and -std=gnu2x. Some of these
features are also supported as extensions when compiling for older
language versions. In addition to the features listed, some
features previously supported as extensions and now added to the C
standard are enabled by default in C2X mode and not diagnosed with
-std=c2x -Wpedantic.
+ Digit separators (as in C++) are supported for C2X.
+ The #elifdef and #elifndef preprocessing directives are now
supported.
+ The printf and scanf format checking with [31]-Wformat now
supports the %b format specified by C2X for binary integers,
and the %B format recommended by C2X for printf.

[32]C++

* Several C++23 features have been implemented:
+ [33]P1938R3, if consteval ([34]PR100974)
+ [35]P0849R8, auto(x): decay-copy in the language
([36]PR103049)
+ [37]P2242R3, Non-literal variables (and labels and gotos) in
constexpr functions ([38]PR102612)
+ [39]P2334R1, Support for preprocessing directives elifdef and
elifndef ([40]PR102616)
+ [41]P2360R0, Extend init-statement to allow alias-declaration
([42]PR102617)
+ [43]P2128R6, Multidimensional subscript operator
+ [44]DR 2397, auto specifier for pointers and references to
arrays ([45]PR100975)
* Several C++ Defect Reports have been resolved, e.g.:
+ [46]DR 960, Covariant functions and lvalue/rvalue references
+ [47]DR 1227, Mixing immediate and non-immediate contexts in
deduction failure
+ [48]DR 1315, Restrictions on non-type template arguments in
partial specializations
+ [49]DR 2082, Referring to parameters in unevaluated operands
of default arguments
+ [50]DR 2351, void{}
+ [51]DR 2374, Overly permissive specification of enum
direct-list-initialization
+ [52]DR 2397, auto specifier for pointers and references to
arrays
+ [53]DR 2446, Questionable type-dependency of concept-ids
* New command-line option -fimplicit-constexpr can be used to make
inline functions implicitly constexpr ([54]git)
* New command-line option -ffold-simple-inlines can be used to fold
calls to certain trivial inline functions (currently std::move,
std::forward, std::addressof and std::as_const). In contrast to
inlining such calls, folding means that no intermediate code or
debug information will be generated for them; this minimizes the
abstraction penalty incurred for using these functions versus using
the fundamental operations from which they're defined (e.g.
std::move versus static_cast). This flag is enabled by default when
-fno-inline is not active.
* Deduction guides can be declared at class scope ([55]PR79501)
* [56]-Wuninitialized warns about using uninitialized variables in
member initializer lists ([57]PR19808)
* [58]-Wint-in-bool-context is now disabled when instantiating a
template ([59]git)
* Stricter checking of attributes on friend declarations: if a friend
declaration has an attribute, that declaration must be a
definition. Moreover, a C++11 attribute cannot appear in the middle
of the decl-specifier-seq. ([60]PR99032)
* New warning options for C++ language mismatches:
-Wc++11-extensions, -Wc++14-extensions, -Wc++17-extensions,
-Wc++20-extensions, and -Wc++23-extensions. They are enabled by
default and can be used to control existing pedwarns about
occurrences of new C++ constructs in code using an old C++ standard
dialect.
* New warning [61]-Wmissing-requires warns about missing requires
([62]git)
* The existing std::is_constant_evaluated in if warning was extended
to warn in more cases ([63]PR100995)
* [64]-Waddress has been enhanced so that it now warns about, for
instance, comparing the address of a nonstatic member function to
null ([65]PR102103)
* Errors about narrowing are no longer hidden if they occur in system
headers
* Ordered comparison of null pointers is now rejected ([66]PR99701)
* Anonymous structs with bases are now rejected ([67]git)
* The compiler rejects taking the address of an immediate member
function ([68]PR102753)
* The compiler has support for C++20
__cpp_lib_is_pointer_interconvertible and
__cpp_lib_is_layout_compatible to help the C++ library implement
[69]P0466, Layout-compatibility and Pointer-interconvertibility
Traits ([70]PR101539)
* Memory usage of constraint subsumption has been improved
([71]PR100828)
* constinit thread_local variables are optimized better
([72]PR101786)
* Support for C++17 std::hardware_destructive_interference_size was
added, along with the [73]-Winterference-size warning ([74]git)
* Many bugs in the CTAD handling have been fixed ([75]PR101344,
[76]PR101883, [77]PR89062, [78]PR101233, [79]PR88252, [80]PR86439,
[81]PR98832, [82]PR102933 ...)
* Two-stage name lookup for dependent operator expressions has been
corrected ([83]PR51577)
* Several issues with constrained variable templates have been fixed
([84]PR98486)
* The compiler performs less instantiating when doing speculative
constant evaluation ([85]git)
* Various diagnostic improvements; e.g., a more precise caret
location for pointer-to-member expressions
* The new -fconstexpr-fp-except flag allows IEC559 floating point
exceptions in constant-expressions.

[86]Runtime Library (libstdc++)

* Improved experimental C++20 support, including:
+ std::vector, std::basic_string, std::optional, and
std::variant can be used in constexpr functions.
+ std::make_shared for arrays with default initialization, and
std::atomic<std::shared_ptr<T>>.
+ Layout-compatibility and pointer-interconvertibility traits.
* Improved experimental C++23 support, including:
+ Monadic operations for std::optional.
+ std::expected
+ std::move_only_function
+ <spanstream>
+ std::basic_string::resize_and_overwrite
+ std::unique_ptr can be used in constexpr functions.
+ <stacktrace> (not built by default, requires linking to an
extra library).
+ <stdatomic.h>
+ std::invoke_r
+ constexpr std::type_info::operator==

[87]D

* New features:
+ Support for the D programming language has been updated to
version 2.100.1 of the language and run-time library. Full
changelog for this release and previous releases can be found
on the [88]dlang.org website.
+ On supported targets, the __traits(compiles) expression can
now be used to determine whether a target-specific built-in is
available without error during CTFE ([89]PR101127).
+ Functions annotated with pragma(inline, true) are now compiled
into every module where they are used from ([90]PR106563).
+ Partial support for directly importing C99 sources into a D
compilation ([91]ImportC) has been added to the language. A
notable missing feature is support for preprocessing C
imports, which can be worked around by preprocessing all C
sources used for importing ahead of time.
* New language options:
+ -fcheck=, enables or disables the code generation of specific
run-time contract checks.
+ -fcheckaction=, controls the run-time behavior on an assert,
array bounds check, or final switch contract failure. The
default is -fcheckaction=throw.
+ -fdump-c++-spec=, dumps all compiled extern(C++) declarations
as C++ code to the given file. The supplementary option
-fdump-c++-spec-verbose turns on emission of comments for
ignored declarations in the generated spec.
+ -fextern-std=, controls which C++ standard extern(C++)
declarations are compiled to be compatible with. The default
is -fextern-std=c++17.
+ -fpreview=, added to enable upcoming D language features in
the compiler.
+ -frevert=, added to revert D language changes to support older
D codebases that need more time to transition.
+ -fsave-mixins=, saves mixins expanded at compile-time to a
file.
* Deprecated and removed features:
+ The -Wtemplates compiler switch has been removed, as it had
been superceded by -ftransition=templates, which more
accurately reports on which templates have been instantiated.
+ The -ftransition=dip25 and -ftransition=dip1000 compiler
switches have been renamed to -fpreview=dip25 and
-fpreview=dip1000.

[92]Fortran

* WG5/N1942, "TS 29113 Further Interoperability of Fortran with C",
is now fully supported. In addition to implementing previously
missing functionality, such as support for character arguments of
length greater than one in functions marked bind(c) and gaps in the
handling for assumed-rank arrays, numerous other bugs have been
fixed, and an extensive set of new conformance test cases has been
added.
* GCC 12 now uses OPERATION as the name of the function to the
CO_REDUCE intrinsic for the pairwise reduction, thus conforming to
the Fortran 2018 standard. Previous versions used OPERATOR which
conforms to TS 18508.
* On POWER systems which support it, the -mabi=ieeelongdouble option
now selects the IEEE 128-bit floating point format for
REAL(KIND=16). R16_IBM and R16_IEEE have been added to the
-fconvert option, the CONVERT specifier of the OPEN statement and
the GFORTRAN_CONVERT_UNIT environment variable.

[93]Go

* GCC 12 provides a complete implementation of the Go 1.18 user
packages.
* Although Go 1.18 includes support for generic programming, that
support is not yet available in GCC.

[94]libgccjit

* The libgccjit API gained 30 new entry points:
+ 17 new "reflection" entry points for querying functions and
types ([95]LIBGCCJIT_ABI_16)
+ [96]gcc_jit_lvalue_set_tls_model for supporting thread-local
variables ([97]LIBGCCJIT_ABI_17)
+ [98]gcc_jit_lvalue_set_link_section for setting the link
section of global variables, analogous to
[99]__attribute__((section(".section")))
([100]LIBGCCJIT_ABI_18)
+ 4 new entry points for initializing global variables and
creating constructors for rvalues ([101]LIBGCCJIT_ABI_19)
+ Support for sized integer types, including 128-bit integers
and helper functions for such types ([102]LIBGCCJIT_ABI_20)
+ [103]gcc_jit_context_new_bitcast for reinterpreting the bits
of an rvalue as a different type ([104]LIBGCCJIT_ABI_21)
+ [105]gcc_jit_lvalue_set_register_name for setting a specific
register for a variable ([106]LIBGCCJIT_ABI_22)
+ [107]gcc_jit_context_set_bool_print_errors_to_stderr
([108]LIBGCCJIT_ABI_23)
+ 2 new entry points for setting the alignment of a variable
([109]LIBGCCJIT_ABI_24)
* libgccjit has gained support for the use of various atomic builtins
([110]PR96066, [111]PR96067)
* [112]gcc_jit_context_new_cast is now able to handle truncation and
extension between different integer types ([113]PR95498)

[114]New Targets and Target Specific Improvements

[115]AArch64 & arm

* Newer revisions of the Arm Architecture are supported as arguments
to the -march option: armv8.7-a, armv8.8-a, armv9-a.
* The Arm Cortex-A510 CPU is now supported through the cortex-a510
argument to the -mcpu and -mtune options.
* GCC can now auto-vectorize operations performing sign-differing
dot-product operations, taking advantage of instructions in the
Advanced SIMD (AArch64/AArch32) and SVE (AArch64) instruction sets.

[116]AArch64

* A number of new CPUs are supported through the -mcpu and -mtune
options (GCC identifiers in parentheses).
+ Ampere-1 (ampere1).
+ Arm Cortex-A710 (cortex-a710).
+ Arm Cortex-X2 (cortex-x2).
* The 64-byte atomic load/store intrinsics to accelerator memory from
the [117]2020 Arm Architecture extensions are supported through the
+ls64 option extension.
* Initial code generation support is supported for hardware
instructions used to accelerate the memcpy,memmove and memset
standard functions. These instructions can be generated when
compiling with the +mopsoption extension.
* The ACLE Advanced SIMD intrinsics accessible through the arm_neon.h
header have been significantly reimplemented and generate
higher-performing code than previous GCC versions.
* The option -mtune=neoverse-512tvb is added to tune for Arm Neoverse
cores that have a total vector bandwidth of 512 bits. Please refer
to the documentation for more details.

[118]AMD Radeon (GCN)

* Debug experience with ROCGDB has been improved.
* Support for the type __int128_t/integer(kind=16) was added.
* For offloading, the limitation of using only one wavefront per
compute unit (CU) has been lifted. Up to 40 workgroups per CU and
16 wavefronts per workgroup are supported (up to a limit of 40
wavefronts in total, per CU). Additionally, the number of used
wavefronts and workgroups was tuned for performance.

[119]arm

* Support is added for accessing the stack canary value via the TLS
register through the -fstack-protector-guard=tls and
-mstack-protector-guard-offset= options. This intended for use in
Linux kernel development. Please refer to the documentation for
more details.

[120]BPF

* Support for CO-RE (compile-once, run-everywhere) has been added to
the BPF back end. CO-RE allows to compile portable BPF programs
that are able to run among different versions of the Linux kernel.

[121]IA-32/x86-64

* New ISA extension support for Intel AVX512-FP16 was added.
AVX512-FP16 intrinsics are available via the -mavx512fp16 compiler
switch.
* For both C and C++ the _Float16 type is supported on x86 systems
with SSE2 enabled. Without {-mavx512fp16}, all operations will be
emulated in software and float instructions.
* Mitigation against straight line speculation (SLS) for function
return and indirect jump is supported via
-mharden-sls=[none|all|return|indirect-jmp].
* Add CS prefix to call and jmp to indirect thunk with branch target
in r8-r15 registers via -mindirect-branch-cs-prefix.
* Always use global offset table (GOT) to access external data and
function symbols when the new -mno-direct-extern-access
command-line option is specified.

[122]LoongArch

* Support for the LoongArch architecture instruction set has been
added.
* The Loongson CPU codename LA464 and LoongArch 64-bit generic CPU
codename loongarch64 are supported through the -march= and -mtune=
options (GCC identifiers in parentheses).
+ Loongson LA464 core (la464).
+ LoongArch 64-bit generic core (loongarch64).

[123]MIPS

* The ABI passing arguments containing zero-width fields (for
example, C/C++ zero-width bit-fields, GNU C/C++ zero-length arrays,
and GNU C empty structs) has changed. Now a zero-width field will
not prevent an aligned 64-bit floating-point field next to it from
being passed through FPR. This is compatible with LLVM, but
incompatible with previous GCC releases. GCC 12 on MIPS will report
such incompatibilities as an inform unless -Wno-psabi is used.
* The ABI returning values containing C++17 empty bases has changed.
Now an empty base will not prevent an aggregate containing only one
or two floating-point fields from being returned through FPR. This
is compatible with GCC 6 and earlier, but incompatible with GCC 7
through 11. GCC 12 on MIPS will report such incompatibilities as an
inform unless -Wno-psabi is used.

[124]NVPTX

* The -march flag has been added. The -misa flag is now considered an
alias of the -march flag.
* Support for PTX ISA target architectures sm_53, sm_70, sm_75 and
sm_80 has been added. These can be specified using the -march flag.
* The default PTX ISA target architecture has been set back to sm_30,
to fix support for sm_30 boards.
* The -march-map flag has been added. The -march-map value will be
mapped to an valid -march flag value. For instance,
-march-map=sm_50 maps to -march=sm_35. This can be used to specify
that generated code is to be executed on a board with at least some
specific compute capability, without having to know the valid
values for the -march flag.
* The -mptx flag has been added to specify the PTX ISA version for
the generated code; permitted values are 3.1 (matches previous GCC
versions), 6.0, 6.3, and 7.0. If not specified, the used version is
the minimal version required for -march but at least 6.0.
* An mptx-3.1 multilib was added. This allows using older drivers
which do not support PTX ISA version 6.0.
* The new __PTX_SM__ predefined macro allows code to check the PTX
ISA target architecture being targeted by the compiler.
* The new __PTX_ISA_VERSION_MAJOR__ and __PTX_ISA_VERSION_MINOR__
predefined macros allows code to check the PTX ISA version being
targeted by the compiler.

[125]PowerPC / PowerPC64 / RS6000

* The internal implementation of Power's target-specific built-in
functions has been rewritten to be easier and less error-prone to
maintain. Every attempt has been made to ensure that the new
behavior matches the old behavior, but inevitably some bugs can be
expected. Please [126]report any problems.
* The built-in functions __builtin_get_texasr, __builtin_get_texasru,
__builtin_get_tfhar, __builtin_get_tfiar, __builtin_set_texasr,
__builtin_set_texasru, __builtin_set_tfhar, and __builtin_set_tfiar
now behave as documented in all supported configurations. On prior
releases, the arguments and return values of these functions were
treated as unsigned long long instead of as unsigned long, when the
options -m32 -mpowerpc64 were in effect.
* The overloaded built-in functions vec_cntlz_lsbb and vec_cnttz_lsbb
now behave as documented. On prior releases, these built-in
functions had incorrect semantics on little-endian targets.

[127]PRU

* The [128]__regio_symbol variable qualifier has been added. It
allows easier access in C programs to the __R30 and __R31 CPU I/O
registers.

[129]RISC-V

* The default ISA spec version was bumped to 20191213; see [130]this
announcement for details.
* New ISA extension support for zba, zbb, zbc, zbs was added.
* New ISA extension support for vector and scalar crypto was added,
only support architecture testing macro and -march= parsing.
* The option -mtune=thead-c906 is added to tune for T-HEAD c906
cores.
* libstdc++ no longer attempts to detect built-in atomics.
Distributions that have out-of-tree workarounds for -latomic should
check their ABIs again.

[131]Operating Systems

[132]Improvements to Static Analyzer

* The analyzer has gained a
[133]-Wanalyzer-use-of-uninitialized-value warning, similar to
[134]-Wuninitialized and [135]-Wmaybe-uninitialized, but based on
an interprocedural path-sensitive analysis ([136]PR95006).
Such warnings are not disabled by the new
[137]-ftrivial-auto-var-init (see below), as the latter is
considered a mitigation option.
* [138]-Wanalyzer-write-to-const and
[139]-Wanalyzer-write-to-string-literal will now check for
[140]__attribute__ ((access, ....)) on calls to externally-defined
functions, and complain about read-only regions pointed to by
arguments marked with a write_only or read_write attribute
([141]PR104793).
* The analyzer's "taint" mode, activated by
[142]-fanalyzer-checker=taint (in addition to [143]-fanalyzer), has
gained four new taint-based warnings:
+ [144]-Wanalyzer-tainted-allocation-size for e.g.
attacker-controlled malloc and alloca,
+ [145]-Wanalyzer-tainted-divisor for detecting where an
attacker can inject a divide-by-zero,
+ [146]-Wanalyzer-tainted-offset for attacker-controlled pointer
offsets,
+ [147]-Wanalyzer-tainted-size for attacker-controlled values
being used as a size parameter to calls to memset or to
functions marked with [148]__attribute__ ((access, ....)).
The existing [149]-Wanalyzer-tainted-array-index has been reworded
to talk about "attacker-controlled" rather than "tainted" values,
for consistency with the new warnings.
A new [150]__attribute__ ((tainted_args)) has been added to the C
and C++ front ends, usable on functions, and on function pointer
callback fields in structs. The analyzer's taint mode will treat
all parameters and buffers pointed to by parameters of such
functions as being attacker-controlled, such as for annotating
system calls in an operating system kernel as being an "attack
surface".
* The analyzer now respects [151]__attribute__((const)): it will
treat such functions as returning the same value when given the
same inputs ([152]PR104434), and as having no side effects
([153]PR104576).
* The analyzer is now able to split its analysis into multiple
execution paths in places where there isn't a split in the control
flow graph. For example, it now handles realloc calls by splitting
the execution path into three possible outcomes for the call:
+ failure, returning NULL
+ success, growing the buffer in-place without moving it
+ success, allocating a new buffer, copying the content of the
old buffer to it, and freeing the old buffer
* The analyzer's interprocedural path exploration logic is now able
to track calls through function pointers.
* The analyzer now makes the assumption that if we know PTR is
non-NULL, then (PTR + OFFSET) is also non-NULL. This isn't strictly
true, but eliminates false positives in practice ([154]PR101962).
* The analyzer has gained some initial support for inline assembler
code. This is extremely limited, and is purely to help suppress
false positives when analyzing the Linux kernel, which makes heavy
use of inline assembler ([155]PR101570).
* The way the analyzer tracks the state of memory along an execution
path has been improved in various ways for GCC 12:
+ An optimization for representing bulk updates to memory (e.g.
zero fills) has been removed as it never worked well. In GCC
12 it has been replaced with a simpler and more accurate
approach, eliminating many false positives ([156]PR95006).
+ Various optimizations have been added, speeding up the
analysis on a particularly problematic source file from 4
minutes down to 17 seconds ([157]PR104943, [158]PR104954, and
[159]PR104955).
+ The analyzer now tracks the sizes of dynamically-allocated
regions, both on the heap (via malloc etc) and stack (via
alloca), though none of the analyzer warnings make use of this
yet in GCC 12.
* The analyzer's handling of switch statements has been rewritten,
fixing various bugs.

Other significant improvements

[160]Eliminating uninitialized variables

* GCC can now [161]initialize all stack variables implicitly,
including padding. This is intended to eliminate all classes of
uninitialized stack variable flaws. Lack of explicit initialization
will still warn when [162]-Wuninitialized is active. For best
debugging, use of the new command-line option
[163]-ftrivial-auto-var-init=pattern can be used to fill variables
with a repeated 0xFE pattern, which tends to illuminate many bugs
(e.g. pointers receive invalid addresses, sizes and indices are
very large). For best production results, the new command-line
option [164]-ftrivial-auto-var-init=zero can be used to fill
variables with 0x00, which tends to provide a safer state for bugs
(e.g. pointers are NULL, strings are NUL filled, and sizes and
indices are 0).

[165]Debugging formats

* GCC can now generate debugging information in [166]CTF, a
lightweight debugging format that provides information about C
types and the association between functions and data symbols and
types. This format is designed to be embedded in ELF files and to
be very compact and simple. A new command-line option -gctf enables
the generation of CTF.
* GCC can now generate debugging information in BTF. This is a
debugging format mainly used in BPF programs and the Linux kernel.
The compiler can generate BTF for any target, when enabled with the
command-line option -gbtf

[167]GCC 12.1

This is the [168]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 12.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[169]GCC 12.2

This is the [170]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 12.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Target Specific Changes

LoongArch

* The default setting of -m[check|no-check]-zero-division is changed
for optimized code. Now -mno-check-zero-division is the default for
all optimization levels but -O0 and -Og. The old behavior can be
obtained by explicitly passing -mcheck-zero-division to GCC.

[171]GCC 12.3

Target Specific Changes

x86-64

* GCC now supports AMD CPUs based on the znver4 core via
-march=znver4. The switch makes GCC consider using 512-bit vectors
when auto-vectorizing.

This is the [172]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 12.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[173]GCC 12.4

This is the [174]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 12.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[175]GCC 12.5

This is the [176]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 12.5 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

For questions related to the use of GCC, please consult these web
pages and the [177]GCC manuals. If that fails, the
[178][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [179][email protected]. All of [180]our lists have public
archives.

Copyright (C) [181]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [182]maintained by the GCC team. Last modified
2025-07-11.

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173. https://gcc.gnu.org/gcc-12/changes.html#12.4
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175. https://gcc.gnu.org/gcc-12/changes.html#12.5
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178. mailto:[email protected]
179. mailto:[email protected]
180. https://gcc.gnu.org/lists.html
181. https://www.fsf.org/
182. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-11/index.html

GCC 11 Release Series

July 19, 2024

The GCC developers are pleased to announce the release of GCC 11.5.

This release is a bug-fix release, containing fixes for regressions in
GCC 11.4 relative to previous releases of GCC.

Release History

GCC 11.5
July 19, 2024 ([1]changes, [2]documentation)

GCC 11.4
May 29, 2023 ([3]changes, [4]documentation)

GCC 11.3
April 21, 2022 ([5]changes, [6]documentation)

GCC 11.2
July 28, 2021 ([7]changes, [8]documentation)

GCC 11.1
April 27, 2021 ([9]changes, [10]documentation)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [11]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [12]GCC
project web site or contact the [13]GCC development mailing list.

To obtain GCC please use [14]our mirror sites or [15]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [16]GCC manuals. If that fails, the
[17][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [18][email protected]. All of [19]our lists have public
archives.

Copyright (C) [20]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [21]maintained by the GCC team. Last modified
2024-07-19.

References

1. https://gcc.gnu.org/gcc-11/changes.html
2. https://gcc.gnu.org/onlinedocs/11.5.0/
3. https://gcc.gnu.org/gcc-11/changes.html
4. https://gcc.gnu.org/onlinedocs/11.4.0/
5. https://gcc.gnu.org/gcc-11/changes.html
6. https://gcc.gnu.org/onlinedocs/11.3.0/
7. https://gcc.gnu.org/gcc-11/changes.html
8. https://gcc.gnu.org/onlinedocs/11.2.0/
9. https://gcc.gnu.org/gcc-11/changes.html
10. https://gcc.gnu.org/onlinedocs/11.1.0/
11. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Contributors.html
12. https://gcc.gnu.org/index.html
13. mailto:[email protected]
14. https://gcc.gnu.org/mirrors.html
15. https://gcc.gnu.org/git.html
16. https://gcc.gnu.org/onlinedocs/
17. mailto:[email protected]
18. mailto:[email protected]
19. https://gcc.gnu.org/lists.html
20. https://www.fsf.org/
21. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-11/changes.html

GCC 11 Release Series
Changes, New Features, and Fixes

This page is a "brief" summary of some of the huge number of
improvements in GCC 11. You may also want to check out our [1]Porting
to GCC 11 page and the [2]full GCC documentation.

Caveats

* The default mode for C++ is now -std=gnu++17 instead of
-std=gnu++14. Note that [3]C++17 changes to template template
parameter matching can be disabled independently of other features
with -fno-new-ttp-matching.
* When building GCC itself, the host compiler must now support C++11,
rather than C++98. In particular bootstrapping GCC 11 using an
older version of GCC requires a binary of GCC 4.8 or later, rather
than of GCC 3.4 or later as was the case for bootstrapping GCC 10.
* Naming and location of auxiliary and dump output files changed. If
you compile multiple input files in a single command, if you enable
Link Time Optimization, or if you use -dumpbase, -dumpdir,
-save-temps=*, and you expect any file other than the primary
output file(s) to be created as a side effect, watch out for
improvements and a few surprises. See [4]the patch, particularly
its textual description, for more details about the changes.
* -gsplit-dwarf no longer enables debug info generation on its own
but requires a separate -g for this.
* The libstdc++ configure option --enable-cheaders=c_std is
deprecated and will be removed in a future release. It should be
possible to use --enable-cheaders=c_global (the default) with no
change in behaviour.
* The front end for compiling BRIG format of Heterogeneous System
Architecture Intermediate Language (HSAIL) has been deprecated and
will likely be removed in a future release.
* Some short options of the gcov tool have been renamed: -i to -j and
-j to -H.

[5]General Improvements

* [6]ThreadSanitizer improvements to support alternative runtimes and
environments. The [7]Linux Kernel Concurrency Sanitizer (KCSAN) is
now supported.
+ Add --param tsan-distinguish-volatile to optionally emit
instrumentation distinguishing volatile accesses.
+ Add --param tsan-instrument-func-entry-exit to optionally
control if function entries and exits should be instrumented.
* In previous releases of GCC, the "column numbers" emitted in
diagnostics were actually a count of bytes from the start of the
source line. This could be problematic, both because of:
+ multibyte characters (requiring more than one byte to encode),
and
+ multicolumn characters (requiring more than one column to
display in a monospace font)
For example, the character p ("GREEK SMALL LETTER PI (U+03C0)")
occupies one column, and its UTF-8 encoding requires two bytes; the
character 🙂 ("SLIGHTLY SMILING FACE (U+1F642)") occupies
two columns, and its UTF-8 encoding requires four bytes.
In GCC 11 the column numbers default to being column numbers,
respecting multi-column characters. The old behavior can be
restored using a new option [8]-fdiagnostics-column-unit=byte.
There is also a new option [9]-fdiagnostics-column-origin=,
allowing the pre-existing default of the left-hand column being
column 1 to be overridden if desired (e.g. for 0-based columns).
The output of [10]-fdiagnostics-format=json has been extended to
supply both byte counts and column numbers for all source
locations.
Additionally, in previous releases of GCC, tab characters in the
source would be emitted verbatim when quoting source code, but be
prefixed with whitespace or line number information, leading to
misalignments in the resulting output when compared with the actual
source. Tab characters are now printed as an appropriate number of
spaces, using the [11]-ftabstop option (which defaults to 8 spaces
per tab stop).
* Introduce [12]Hardware-assisted AddressSanitizer support. This
sanitizer currently only works for the AArch64 target. It helps
debug address problems similarly to [13]AddressSanitizer but is
based on partial hardware assistance and provides probabilistic
protection to use less RAM at run time. [14]Hardware-assisted
AddressSanitizer is not production-ready for user space, and is
provided mainly for use compiling the Linux Kernel.
To use this sanitizer the command line arguments are:
+ -fsanitize=hwaddress to instrument userspace code.
+ -fsanitize=kernel-hwaddress to instrument kernel code.
* For targets that produce DWARF debugging information GCC now
defaults to [15]DWARF version 5 (with the exception of VxWorks and
Darwin/Mac OS X which default to version 2 and AIX which defaults
to version 4). This can produce up to 25% more compact debug
information compared to earlier versions.
To take full advantage of DWARF version 5 GCC needs to be built
against binutils version 2.35.2 or higher. When GCC is built
against earlier versions of binutils GCC will still emit DWARF
version 5 for most debuginfo data, but will generate version 4
debug line tables (even when explicitly given -gdwarf-5).
The following debug information consumers can process DWARF version
5:
+ GDB 8.0, or higher
+ valgrind 3.17.0
+ elfutils 0.172, or higher (for use with systemtap,
dwarves/pahole, perf and libabigail)
+ dwz 0.14
Programs embedding libbacktrace are urged to upgrade to the version
shipping with GCC 11.
To make GCC 11 generate an older DWARF version use -g together with
-gdwarf-2, -gdwarf-3 or -gdwarf-4.
* Vectorizer improvements:
+ The straight-line code vectorizer now considers the whole
function when vectorizing and can handle opportunities
crossing CFG merges and backedges.
* A series of conditional expressions that compare the same variable
can be transformed into a switch statement if each of them contains
a comparison expression. Example:
int IsHTMLWhitespace(int aChar) {
return aChar == 0x0009 || aChar == 0x000A ||
aChar == 0x000C || aChar == 0x000D ||
aChar == 0x0020;
}

This statement can be transformed into a switch statement and then
expanded into a bit-test.
* New command-line options:
+ [16]-fbit-tests, enabled by default, can be used to enable or
disable switch expansion using bit-tests.
* Inter-procedural optimization improvements:
+ A new IPA-modref pass was added to track side effects of
function calls and improve precision of points-to-analysis.
The pass can be controlled by the [17]-fipa-modref option.
+ The identical code folding pass (controlled by [18]-fipa-icf)
was significantly improved to increase the number of unified
functions and to reduce compile-time memory use.
+ IPA-CP (Interprocedural constant propagation) heuristics
improved its estimation of potential usefulness of known loop
bounds and strides by taking the estimated frequency of these
loops into account.
* Link-time optimization improvements:
+ The LTO bytecode format was optimized for smaller object files
and faster streaming.
+ Memory allocation of the linking stage was improved to reduce
peak memory use.
* Profile driven optimization improvements:
+ Using [19]-fprofile-values, was improved by tracking more
target values for e.g. indirect calls.
+ GCOV data file format outputs smaller files by representing
zero counters in a more compact way.

[20]New Languages and Language specific improvements

* GCC 11 adds support for non-rectangular loop nests in OpenMP
constructs and the allocator routines of [21]OpenMP 5.0, including
initial allocate clause support in C/C++. The OMP_TARGET_OFFLOAD
environment variable and the active-levels routines are now
supported. For C/C++, the declare variant and map support has been
extended. For Fortran, OpenMP 4.5 is now fully supported and OpenMP
5.0 support has been extended, including the following features
which were before only available in C and C++: order(concurrent),
device_type, memorder-clauses for flush, lastprivate with
conditional modifier, atomic construct and reduction clause
extensions of OpenMP 5.0, if clause with simd and cancel modifiers,
target data without map clause, and limited support for the
requires construct.
* Version 2.6 of the [22]OpenACC specification continues to be
maintained and improved in the C, C++ and Fortran compilers. See
the [23]implementation status section on the OpenACC wiki page and
the [24]run-time library documentation for further information.

[25]C family

* New attributes:
+ The [26]no_stack_protector attribute has been added to mark
functions which should not be instrumented with stack
protection (-fstack-protector).
+ The existing [27]malloc attribute has been extended so that it
can be used to identify allocator/deallocator API pairs. A
pair of new [28]-Wmismatched-dealloc and
[29]-Wmismatched-new-delete warnings will complain about
mismatched calls, and [30]-Wfree-nonheap-object about
deallocation calls with pointers not obtained from allocation
functions. Additionally, the static analyzer will use these
attributes when checking for leaks, double-frees,
use-after-frees, and similar issues.
* New warnings:
+ [31]-Wmismatched-dealloc, enabled by default, warns about
calls to deallocation functions with pointers returned from
mismatched allocation functions.
+ [32]-Wsizeof-array-div, enabled by -Wall, warns about
divisions of two sizeof operators when the first one is
applied to an array and the divisor does not equal the size of
the array element.
+ [33]-Wstringop-overread, enabled by default, warns about calls
to string functions reading past the end of the arrays passed
to them as arguments. In prior GCC releases most instances of
his warning are diagnosed by -Wstringop-overflow.
+ [34]-Wtsan, enabled by default, warns about unsupported
features in ThreadSanitizer (currently
std::atomic_thread_fence).
* Enhancements to existing warnings:
+ [35]-Wfree-nonheap-object detects many more instances of calls
to deallocation functions with pointers not returned from a
dynamic memory allocation function.
+ [36]-Wmaybe-uninitialized diagnoses passing pointers or
references to uninitialized memory to functions taking
const-qualified arguments.
+ [37]-Wuninitialized detects reads from uninitialized
dynamically allocated memory.
* For ELF targets that support the GNU or FreeBSD OSABIs, the used
attribute will now save the symbol declaration it is applied to
from linker garbage collection.
To support this behavior, used symbols that have not been placed in
specific sections (e.g. with the section attribute, or the
-f{function,data}-sections options) will be placed in new, unique
sections.
This functionality requires Binutils version 2.36 or later.

[38]C

* Several new features from the upcoming C2X revision of the ISO C
standard are supported with -std=c2x and -std=gnu2x. Some of these
features are also supported as extensions when compiling for older
language versions. In addition to the features listed, some
features previously supported as extensions and now added to the C
standard are enabled by default in C2X mode and not diagnosed with
-std=c2x -Wpedantic.
+ The BOOL_MAX and BOOL_WIDTH macros are provided in <limits.h>.
+ As in C++, function definitions no longer need to give names
for unused function parameters.
+ The expansions of the true and false macros in <stdbool.h>
have changed so that they have type bool.
+ The [[nodiscard]] standard attribute is now supported.
+ The __has_c_attribute preprocessor operator is now supported.
+ Macros INFINITY, NAN, FLT_SNAN, DBL_SNAN, LDBL_SNAN,
DEC_INFINITY, DEC_NAN, and corresponding signaling NaN macros
for _FloatN, _FloatNx and _DecimalN types, are provided in
<float.h>. There are also corresponding built-in functions
__builtin_nansdN for decimal signaling NaNs.
+ Macros FLT_IS_IEC_60559, DBL_IS_IEC_60559 and
LDBL_IS_IEC_60559 are provided in <float.h>.
+ The feature test macro __STDC_WANT_IEC_60559_EXT__ is
supported by <float.h>.
+ Labels may appear before declarations and at the end of a
compound statement.
* New warnings:
+ [39]-Warray-parameter, enabled by -Wall, warns about
redeclarations of functions with ordinary array arguments
declared using inconsistent forms. The warning also enables
the detection of the likely out of bounds accesses in calls to
such functions with smaller arrays.
+ [40]-Wvla-parameter, enabled by -Wall, warns redeclarations of
functions with variable length array arguments declared using
inconsistent forms or with mismatched bounds. The warning also
enables the detection of the likely out of bounds accesses in
calls to such functions with smaller arrays.

[41]C++

* The default mode has been changed to -std=gnu++17.
* Several C++20 features have been implemented:
+ the compiler now supports consteval virtual functions
+ P2082R1, Fixing CTAD for aggregates
+ P0593R6, Pseudo-destructors end object lifetimes
+ P1907R1, Inconsistencies with non-type template parameters
(complete implementation)
+ P1975R0, Fixing the wording of parenthesized
aggregate-initialization
+ P1009R2, Array size deduction in new-expressions
+ P1099R5, using enum
+ Modules, Requires -fmodules-ts and some aspects are
incomplete. Refer to [42]C++ 20 Status
* The C++ front end has experimental support for some of the upcoming
C++23 draft features with the -std=c++23, -std=gnu++23, -std=c++2b
or -std=gnu++2b flags, including
+ P0330R8, Literal Suffix for (signed) size_t.
For a full list of new features, see [43]the C++ status page.
* Several C++ Defect Reports have been resolved, e.g.:
+ DR 625, Use of auto as a template-argument
+ DR 1512, Pointer comparison vs qualification conversions
+ DR 1722, Should lambda to function pointer conversion function
be noexcept?
+ DR 1914, Duplicate standard attributes
+ DR 2032, Default template-arguments of variable templates
+ DR 2289, Uniqueness of decomposition declaration names
+ DR 2237, Can a template-id name a constructor?
+ DR 2303, Partial ordering and recursive variadic inheritance
+ DR 2369, Ordering between constraints and substitution
+ DR 2450, braced-init-list as a template-argument
* G++ now performs better access checking in templates ([44]PR41437).
* reinterpret_casts in constexpr evaluation are now checked more
completely ([45]PR95307).
* The diagnostic for static_assert has been improved: the compiler
now shows the expression including its template arguments (if there
were any), and can point to the failing clause if the condition
comprised of any logical AND operators ([46]PR97518).
* New warnings:
+ [47]-Wctad-maybe-unsupported, disabled by default, warns about
performing class template argument deduction on a type with no
deduction guides.
+ [48]-Wrange-loop-construct, enabled by -Wall, warns when a
range-based for-loop is creating unnecessary and expensive
copies.
+ [49]-Wdeprecated-enum-enum-conversion, enabled by default in
C++20, warns about deprecated arithmetic conversions on
operands of enumeration types, as outlined in
[depr.arith.conv.enum].
+ [50]-Wdeprecated-enum-float-conversion, enabled by default in
C++20, warns about deprecated arithmetic conversions on
operands where one is of enumeration type and the other is of
a floating-point type, as outlined in [depr.arith.conv.enum].
+ [51]-Wmismatched-new-delete, enabled by -Wall, warns about
calls to C++ operator delete with pointers returned from
mismatched forms of operator new or from other mismatched
allocation functions.
+ [52]-Wvexing-parse, enabled by default, warns about the most
vexing parse rule: the cases when a declaration looks like a
variable definition, but the C++ language requires it to be
interpreted as a function declaration.
* Enhancements to existing warnings:
+ [53]-Wnonnull considers the implicit this argument of every
C++ nonstatic member function to have been implicitly declared
with attribute nonnull and triggers warnings for calls where
the pointer is null.

[54]Runtime Library (libstdc++)

* Improved C++17 support, including:
+ std::from_chars and std::to_chars for floating-point types.
* Improved experimental C++20 support, including:
+ Calendar additions to <chrono>. Thanks to Cassio Neri for
optimizations.
+ std::bit_cast
+ std::source_location
+ Atomic wait and notify operations.
+ <barrier>, <latch>, and <semaphore>
+ <syncstream>
+ Efficient access to basic_stringbuf's buffer.
+ Heterogeneous lookup in unordered containers.
* Experimental C++23 support, including:
+ contains member functions for strings, thanks to Paul Fee.
+ std::to_underlying, std::is_scoped_enum
* Experimental support for Data-Parallel Types (simd) from the
Parallelism 2 TS, thanks to Matthias Kretz.
* Faster std::uniform_int_distribution, thanks to Daniel Lemire.

[55]D

* New features:
+ A new bottom type typeof(*null) has been added to represent
run-time errors and non-terminating functions. This also
introduces a new standard alias for the type named noreturn,
and is implicitly imported into every module.
+ Printf-like and scanf-like functions are now detected by
prefixing them with pragma(printf) for printf-like functions
or pragma(scanf) for scanf-like functions.
+ The __traits() expression now supports the extensions
isDeprecated, isDisabled, isFuture, isModule, isPackage,
child, isReturnOnStack, isZeroInit, getTargetInfo,
getLocation, hasPostblit, isCopyable, getVisibility, and
totype.
+ An expression-based contract syntax has been added to the
language.
+ Function literals can now return a value by reference with the
ref keyword.
+ A new syntax is available to declare aliases to function types
using the alias syntax based on the assignment operator.
+ New types __c_complex_float, __c_complex_double,
__c_complex_real, and __c_wchar_t have been added for
interfacing with C and C++ code, and are available from the
core.stdc.config module.
+ User-defined attributes can now be used to annotate enum
members, alias declarations, and function parameters.
+ Template alias parameters can now be instantiated with basic
types such as int or void function().
+ The mixin construct can now be used as types in the form
mixin(string) var.
+ The mixin construct can now take an argument list, same as
pragma(msg).
* New intrinsics:
+ Bitwise rotate intrinsics core.bitop.rol and core.bitop.ror
have been added.
+ Byte swap intrinsic core.bitop.byteswap for swapping bytes in
a 2-byte ushort has been added.
+ Math intrinsics available from core.math now have overloads
for float and double types.
+ Volatile intrinsics core.volatile.volatileLoad and
core.volatile.volatileStore have been moved from the
core.bitop module.
* New attributes:
+ The following GCC attributes are now recognized and available
from the gcc.attributes module with short-hand aliases for
convenience:
o @attribute("alloc_size", arguments) or
@alloc_size(arguments).
o @attribute("always_inline") or @always_inline.
o @attribute("used") or @used.
o @attribute("optimize", arguments) or
@optimize(arguments).
o @attribute("cold") or @cold.
o @attribute("noplt") or @noplt.
o @attribute("target_clones", arguments) or
@target_clones(arguments).
o @attribute("no_icf") or @no_icf.
o @attribute("noipa") or @noipa.
o @attribute("symver", arguments) or @symver(arguments).
+ New aliases have been added to gcc.attributes for
compatibility with ldc.attributes.
o The @allocSize(arguments) attribute is the same as
@alloc_size(arguments), but uses a 0-based index for
function arguments.
o The @assumeUsed attribute is an alias for
@attribute("used").
o The @fastmath attribute is an alias for
@optimize("Ofast").
o The @naked attribute is an alias for @attribute("naked").
This attribute may not be available on all targets.
o The @restrict attribute has been added to specify that a
function parameter is to be restrict-qualified in the C99
sense of the term.
o The @optStrategy(strategy) attribute is an alias for
@optimize("O0") when the strategy is "none", otherwise
@optimize("Os") for the "optsize" and "minsize"
strategies.
o The @polly attribute is an alias for
@optimize("loop-parallelize-all").
o The @section(name) attribute is an alias for
@attribute("section", name).
o The @target(arguments) attribute is an alias for
attribute("target", arguments).
o The @weak attribute is an alias for @attribute("weak").
* New language options:
+ -fweak-templates, added to control whether declarations that
can be defined in multiple objects should be emitted as weak
symbols. The default is to emit all symbols with extern
linkage as weak, unless the target lacks support for weak
symbols.
+ -Wdeprecated, this option is now enabled by default.
+ -Wextra, this option now turns on all warnings that are not
part of the core D language front-end - -Waddress,
-Wcast-result, -Wunknown-pragmas.
+ -Wvarargs, added to turn on warnings about questionable usage
of the va_start intrinsic.
* Deprecated and removed features:
+ Compiler-recognized attributes are now made available from the
gcc.attributes module, the former module gcc.attribute has
been deprecated and will be removed in a future release.
+ The @attribute("alias") attribute has been removed, as it had
been superseded by pragma(mangle).
+ The @attribute("forceinline") attribute has been removed and
renamed to @always_inline.
+ __vector types that are not supported in hardware are now
rejected at compile-time. Previously all vector types were
accepted by the compiler and emulated when target support was
absent.
+ The extern(Pascal) linkage attribute has been removed.
+ The deprecation phase for -ftransition=import and
-ftransition=checkimports is finished. These switches no
longer have an effect and are now removed. Symbols that are
not visible in a particular scope will no longer be found by
the compiler.
+ It is now an error to use private variables selectively
imported from other modules. Due to a bug, some imported
private members were visible from other modules, violating the
specification.
+ The -fweak compiler switch has been removed, as it existed
only for testing.

[56]Fortran

* Added DEPRECATED to !GCC$'s attributes directive.

[57]Go

* GCC 11 provides a complete implementation of the Go 1.16.3 user
packages.

[58]libgccjit

* libgccjit was marked as merely "Alpha" quality when [59]originally
added in GCC 5. Given that we have maintained [60]API and ABI
compatibility since then and it is in use by various projects, we
have removed that caveat.
* libgccjit can now be built for MinGW
* The libgccjit API gained 10 new entry points:
+ [61]gcc_jit_global_set_initializer
+ 9 entrypoints for [62]directly embedding asm statements into a
compile, analogous to inline asm in the C front end

[63]New Targets and Target Specific Improvements

[64]AArch64 & arm

* A number of new CPUs are supported through arguments to the -mcpu
and -mtune options in both the arm and aarch64 back ends (GCC
identifiers in parentheses):
+ Arm Cortex-A78 (cortex-a78).
+ Arm Cortex-A78AE (cortex-a78ae).
+ Arm Cortex-A78C (cortex-a78c).
+ Arm Cortex-X1 (cortex-x1).
+ Arm Neoverse V1 (neoverse-v1).
+ Arm Neoverse N2 (neoverse-n2).
* GCC can now auto-vectorize operations performing addition,
subtraction, multiplication and the accumulate/subtract variants on
complex numbers, taking advantage of the Advanced SIMD instructions
in the Armv8.3-a (AArch64/AArch32), SVE (AArch64), SVE2 (AArch64)
and MVE (AArch32 M-profile) instruction sets.

[65]AArch64

* In addition to the above, the following AArch64-only CPUs are now
supported:
+ Fujitsu A64FX (a64fx).
+ Arm Cortex-R82 (cortex-r82).
* The AArch64 Armv8-R architecture is now supported through the
-march=armv8-r option.
* Mitigation against the [66]Straight-line Speculation vulnerability
is supported with the -mharden-sls= option. Please refer to the
documentation for usage instructions.
* The availability of Advanced SIMD intrinsics available through the
arm_neon.h header is improved and GCC 11 supports the full set of
intrinsics defined by ACLE Q3 2020.

[67]AMD Radeon (GCN)

* Initial support for gfx908 GPUs has been added.

[68]arm

* Initial auto-vectorization is now available when targeting the MVE
instruction set.
* GCC can now make use of the Low Overhead Branch instruction in
Armv8.1-M to optimize loop counters and checks.
* The -mcpu=cortex-m55 option now supports the extensions +nomve and
+nomve.fp to control generation of MVE and MVE floating-point
instructions.

[69]IA-32/x86-64

* New ISA extension support for Intel TSXLDTRK was added to GCC.
TSXLDTRK intrinsics are available via the -mtsxldtrk compiler
switch.
* New ISA extension support for Intel SERIALIZE was added to GCC.
SERIALIZE intrinsics are available via the -mserialize compiler
switch.
* New ISA extension support for Intel HRESET was added to GCC. HRESET
intrinsics are available via the -mhreset compiler switch.
* New ISA extension support for Intel UINTR was added to GCC. UINTR
intrinsics are available via the -muintr compiler switch.
* New ISA extension support for Intel KEYLOCKER was added to GCC.
KEYLOCKER intrinsics are available via the -mkeylocker compiler
switch.
* New ISA extension support for Intel AMX-TILE, AMX-INT8, AMX-BF16
was added to GCC. AMX-TILE, AMX-INT8, AMX-BF16 intrinsics are
available via the -mamx-tile, -mamx-int8, -mamx-bf16 compiler
switches.
* New ISA extension support for Intel AVX-VNNI was added to GCC.
AVX-VNNI intrinsics are available via the -mavxvnni compiler
switch.
* GCC now supports the Intel CPU named Sapphire Rapids through
-march=sapphirerapids. The switch enables the MOVDIRI, MOVDIR64B,
AVX512VP2INTERSECT, ENQCMD, CLDEMOTE, SERIALIZE, PTWRITE, WAITPKG,
TSXLDTRK, AMT-TILE, AMX-INT8, AMX-BF16, and AVX-VNNI ISA
extensions.
* GCC now supports the Intel CPU named Alderlake through
-march=alderlake. The switch enables the CLDEMOTE, PTWRITE,
WAITPKG, SERIALIZE, KEYLOCKER, AVX-VNNI, and HRESET ISA extensions.
* GCC now supports the Intel CPU named Rocketlake through
-march=rocketlake. Rocket Lake is based on Icelake client and minus
SGX.
* GCC now supports AMD CPUs based on the znver3 core via
-march=znver3.
* GCC now supports micro-architecture levels defined in the x86-64
psABI via -march=x86-64-v2, -march=x86-64-v3 and -march=x86-64-v4.

[70]Nios II

* The options -mcustom-insn=N no longer produce compiler warnings if
the custom instruction is not generated due to missing optimization
options such as -fno-math-errno, -ffinite-math-only, or
-funsafe-math-optimizations. These warnings were not consistently
emitted for all custom instructions.
* The -mcustom-fpu-cfg=fph2 option has been added to enable the
custom instructions supported by the Nios II Floating Point
Hardware 2 Component.

[71]NVPTX

* The -misa default has changed from sm_30 to sm_35.
* The -m32 compiler switch has been removed.
* The -msoft-stack-reserve-local format has been fixed. Previously,
it accepted -msoft-stack-reserve-local<n>. It now accepts
-msoft-stack-reserve-local=<n>.

[72]S/390, System z, IBM Z Systems

* The behavior when compiling with -fexcess-precision=standard (e.g.,
implied by -std=c99) on s390(x) targets can now be controlled at
configure time with the flag --enable-s390-excess-float-precision.
When enabled, GCC will maintain previous behavior and evaluate
float expressions in double precision, which aligns with the
definition of float_t as double. With the flag disabled, GCC will
always evaluate float expressions in single precision. In native
builds and cross compiles that have target libc headers, GCC will
by default match the definition of float_t in the installed glibc.

[73]RISC-V

* Support address sanitizer for RISC-V.
* Support big-endian for RISC-V, thanks to Marcus Comstedt.
* Implement new style of architecture extension test macros: each
architecture extension has a corresponding feature test macro,
which can be used to test its existence and version information.
* Legacy architecture extension test macros like __riscv_atomic are
deprecated, but will still be supported for at least 2 release
cycles.
* Support IFUNC for riscv*-*-linux*.
* Add new option -misa-spec=* to control ISA spec version. This
controls the default version of each extensions. It defaults to
2.2.
* Introduce the --with-multilib-generator configure time option. This
allows for flexible config multi-lib settings. Its syntax is the
same as RISC-V's multilib-generator.
* Extend the sytax for multilib-generator, support expansion operator
* to reduce the complexity of complicated multi-lib re-use rules.
* Support -mcpu=* option aligned with RISC-V clang/LLVM. It sets the
pipeline model and architecture extensions, like -mtune=* plus
-march=*.
* Support for TLS stack protector canary access, thanks to Cooper Qu.
* Support __builtin_thread_pointer for RISC-V.
* Introduce shorten_memrefs optimization, which reduces the code size
for memory access, thanks to Craig Blackmore.

[74]Operating Systems

[75]AIX

* GCC for AIX can be built as a 64-bit application and the runtime is
built as FAT libraries containing both 32-bit and 64-bit objects.
* Support AIX Vector Extended ABI with -mabi=vec-extabi.
* Thread-Local uninitiated data placed in local common section.
* Use thread-safe access in ctype.
* Link with libc128.a when long-double-128 enabled.

[76]Improvements to Static Analyzer

* The implementation of how program state is tracked within
[77]-fanalyzer has been completely rewritten for GCC 11, fixing
numerous bugs, and allowing for the analyzer to scale to larger C
source files.
* The analysis of allocations and deallocations has been generalized
beyond malloc and free.
+ As preliminary work towards eventually supporting C++, the
malloc/free checking will also check new/delete and
new[]/delete[]. However, C++ is not yet properly supported by
[78]-fanalyzer (for example, exception-handling is
unimplemented).
+ As noted above, the existing [79]malloc attribute has been
extended so that it can be used to identify
allocator/deallocator API pairs. The analyzer will use these
attributes when checking for leaks, double-frees,
use-after-frees, and similar issues.
+ A new [80]-Wanalyzer-mismatching-deallocation warning has been
added, covering such mismatches as using scalar delete rather
vector delete[].
* The analyzer has gained warnings
[81]-Wanalyzer-shift-count-negative,
[82]-Wanalyzer-shift-count-overflow, [83]-Wanalyzer-write-to-const,
and [84]-Wanalyzer-write-to-string-literal, all enabled by default
when [85]-fanalyzer is enabled.
* The analyzer can now be extended by GCC plugins, allowing for
domain-specific path-sensitive warnings. An example of using a
[86]GCC plugin to check for misuses of CPython's global interpreter
lock can be seen in the test suite
* The analyzer has gained new debugging options
[87]-fdump-analyzer-json and [88]-fno-analyzer-feasibility.

Other significant improvements

* GCC has gained a new environment variable
[89]GCC_EXTRA_DIAGNOSTIC_OUTPUT which can be used by IDEs to
request machine-readable fix-it hints without needing to adjust
build flags.

[90]GCC 11.1

This is the [91]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 11.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[92]GCC 11.2

This is the [93]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 11.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[94]GCC 11.3

This is the [95]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 11.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[96]GCC 11.4

This is the [97]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 11.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Target Specific Changes

x86-64

* The x86-64 ABI of passing and returning structure with a 64-bit
single precision vector changed in GCC 11.1 when 3DNOW is disabled.
Disabling 3DNOW no longer changes how they are passed nor returned.
This ABI change is now diagnosed with -Wpsabi.
* Mitigation against straight line speculation (SLS) for function
return and indirect jump is supported via
-mharden-sls=[none|all|return|indirect-jmp].
* Add CS prefix to call and jmp to indirect thunk with branch target
in r8-r15 registers via -mindirect-branch-cs-prefix.

[98]GCC 11.5

This is the [99]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 11.5 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Caveats

aarch64

* Due to a bug introduced a few weeks before the 11.5.0 release if
the compiler is configured without explicit --with-arch=,
--with=cpu= and/or --with-tune= configure options the compiler
without explicit -march= etc. options might act as if asked for
cortex-a34. This can be fixed by applying manually the
[100]r12-8060 commit patch on top of GCC 11.5.0. See [101]PR116029
for more details. GCC 11.4.0 or earlier releases are not affected.

For questions related to the use of GCC, please consult these web
pages and the [102]GCC manuals. If that fails, the
[103][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [104][email protected]. All of [105]our lists have public
archives.

Copyright (C) [106]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [107]maintained by the GCC team. Last modified
2025-01-31.

References

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2. https://gcc.gnu.org/onlinedocs/index.html#current
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15. https://dwarfstd.org/doc/DWARF5.pdf
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18. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Optimize-Options.html#index-fipa-ocf
19. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Optimize-Options.html#index-fprofile-values
20. https://gcc.gnu.org/gcc-11/changes.html#languages
21. https://www.openmp.org/specifications/
22. https://www.openacc.org/
23. https://gcc.gnu.org/wiki/OpenACC/Implementation%20Status#status-11
24. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/libgomp/Enabling-OpenACC.html
25. https://gcc.gnu.org/gcc-11/changes.html#c-family
26. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Common-Function-Attributes.html#index-no_005fstack_005fprotector-function-attribute
27. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Common-Function-Attributes.html#index-malloc-function-attribute
28. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Warning-Options.html#index-Wmismatched-dealloc
29. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/C_002b_002b-Dialect-Options.html#index-Wmismatched-new-delete
30. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Warning-Options.html#index-Wfree-nonheap-object
31. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Warning-Options.html#index-Wmismatched-dealloc
32. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Warning-Options.html#index-Wsizeof-array-div
33. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Warning-Options.html#index-Wstringop-overread
34. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Warning-Options.html#index-Wtsan
35. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Warning-Options.html#index-Wfree-nonheap-object
36. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Warning-Options.html#index-Wmaybe-uninitialized
37. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Warning-Options.html#index-Wuninitialized
38. https://gcc.gnu.org/gcc-11/changes.html#c
39. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Warning-Options.html#index-Warray-parameter
40. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Warning-Options.html#index-Wvla-parameter
41. https://gcc.gnu.org/gcc-11/changes.html#cxx
42. https://gcc.gnu.org/projects/cxx-status.html#cxx20
43. https://gcc.gnu.org/projects/cxx-status.html#cxx23
44. https://gcc.gnu.org/PR41437
45. https://gcc.gnu.org/PR95307
46. https://gcc.gnu.org/PR97518
47. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/C_002b_002b-Dialect-Options.html#index-Wctad-maybe-unsupported
48. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/C_002b_002b-Dialect-Options.html#index-Wrange-loop-construct
49. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/C_002b_002b-Dialect-Options.html#index-Wdeprecated-enum-enum-conversion
50. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/C_002b_002b-Dialect-Options.html#index-Wdeprecated-enum-float-conversion
51. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/C_002b_002b-Dialect-Options.html#index-Wmismatched-new-delete
52. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/C_002b_002b-Dialect-Options.html#index-Wvexing-parse
53. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Warning-Options.html#index-Wnonnull
54. https://gcc.gnu.org/gcc-11/changes.html#libstdcxx
55. https://gcc.gnu.org/gcc-11/changes.html#d
56. https://gcc.gnu.org/gcc-11/changes.html#fortran
57. https://gcc.gnu.org/gcc-11/changes.html#go
58. https://gcc.gnu.org/gcc-11/changes.html#jit
59. https://gcc.gnu.org/gcc-5/changes.html#jit
60. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/jit/topics/compatibility.html
61. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/jit/topics/expressions.html#c.gcc_jit_global_set_initializer
62. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/jit/topics/asm.html
63. https://gcc.gnu.org/gcc-11/changes.html#targets
64. https://gcc.gnu.org/gcc-11/changes.html#arm-targets
65. https://gcc.gnu.org/gcc-11/changes.html#aarch64
66. https://developer.arm.com/documentation/102587/0102/Straight-line-speculation-frequently-asked-questions
67. https://gcc.gnu.org/gcc-11/changes.html#amdgcn
68. https://gcc.gnu.org/gcc-11/changes.html#arm
69. https://gcc.gnu.org/gcc-11/changes.html#x86
70. https://gcc.gnu.org/gcc-11/changes.html#nios2
71. https://gcc.gnu.org/gcc-11/changes.html#nvptx
72. https://gcc.gnu.org/gcc-11/changes.html#s390
73. https://gcc.gnu.org/gcc-11/changes.html#riscv
74. https://gcc.gnu.org/gcc-11/changes.html#os
75. https://gcc.gnu.org/gcc-11/changes.html#aix
76. https://gcc.gnu.org/gcc-11/changes.html#analyzer
77. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Static-Analyzer-Options.html
78. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Static-Analyzer-Options.html
79. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Common-Function-Attributes.html#index-malloc-function-attribute
80. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Static-Analyzer-Options.html#index-Wanalyzer-mismatching-deallocation
81. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Static-Analyzer-Options.html#index-Wanalyzer-shift-count-negative
82. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Static-Analyzer-Options.html#index-Wanalyzer-shift-count-overflow
83. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Static-Analyzer-Options.html#index-Wanalyzer-write-to-const
84. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Static-Analyzer-Options.html#index-Wanalyzer-write-to-string-literal
85. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Static-Analyzer-Options.html
86. https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=66dde7bc64b75d4a338266333c9c490b12d49825
87. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Static-Analyzer-Options.html#index-fdump-analyzer-json
88. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Static-Analyzer-Options.html#index-fno-analyzer-feasibility
89. https://gcc.gnu.org/onlinedocs/gcc-11.1.0/gcc/Environment-Variables.html#index-GCC_005fEXTRA_005fDIAGNOSTIC_005fOUTPUT
90. https://gcc.gnu.org/gcc-11/changes.html#11.1
91. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=11.0
92. https://gcc.gnu.org/gcc-11/changes.html#11.2
93. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=11.2
94. https://gcc.gnu.org/gcc-11/changes.html#11.3
95. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=11.3
96. https://gcc.gnu.org/gcc-11/changes.html#11.4
97. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=11.4
98. https://gcc.gnu.org/gcc-11/changes.html#11.5
99. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=11.5
100. https://gcc.gnu.org/r12-8060
101. https://gcc.gnu.org/PR116029
102. https://gcc.gnu.org/onlinedocs/
103. mailto:[email protected]
104. mailto:[email protected]
105. https://gcc.gnu.org/lists.html
106. https://www.fsf.org/
107. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-10/index.html

GCC 10 Release Series

(This release series is no longer supported.)

July, 7, 2023

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 10.5.

This release is a bug-fix release, containing fixes for regressions in
GCC 10.4 relative to previous releases of GCC.

Release History

GCC 10.5
July 7, 2023 ([2]changes, [3]documentation)

GCC 10.4
June 28, 2022 ([4]changes, [5]documentation)

GCC 10.3
April 8, 2021 ([6]changes, [7]documentation)

GCC 10.2
July 23, 2020 ([8]changes, [9]documentation)

GCC 10.1
May 7, 2020 ([10]changes, [11]documentation)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [12]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [13]GCC
project web site or contact the [14]GCC development mailing list.

To obtain GCC please use [15]our mirror sites or [16]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [17]GCC manuals. If that fails, the
[18][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [19][email protected]. All of [20]our lists have public
archives.

Copyright (C) [21]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [22]maintained by the GCC team. Last modified
2024-05-30.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-10/changes.html
3. https://gcc.gnu.org/onlinedocs/10.5.0/
4. https://gcc.gnu.org/gcc-10/changes.html
5. https://gcc.gnu.org/onlinedocs/10.4.0/
6. https://gcc.gnu.org/gcc-10/changes.html
7. https://gcc.gnu.org/onlinedocs/10.3.0/
8. https://gcc.gnu.org/gcc-10/changes.html
9. https://gcc.gnu.org/onlinedocs/10.2.0/
10. https://gcc.gnu.org/gcc-10/changes.html
11. https://gcc.gnu.org/onlinedocs/10.1.0/
12. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Contributors.html
13. https://gcc.gnu.org/index.html
14. mailto:[email protected]
15. https://gcc.gnu.org/mirrors.html
16. https://gcc.gnu.org/git.html
17. https://gcc.gnu.org/onlinedocs/
18. mailto:[email protected]
19. mailto:[email protected]
20. https://gcc.gnu.org/lists.html
21. https://www.fsf.org/
22. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-10/changes.html

GCC 10 Release Series
Changes, New Features, and Fixes

This page is a "brief" summary of some of the huge number of
improvements in GCC 10. You may also want to check out our [1]Porting
to GCC 10 page and the [2]full GCC documentation.

Caveats

* An ABI incompatibility between C++14 and C++17 has been fixed. On
some targets a class with a zero-sized subobject would be passed
incorrectly when compiled as C++17 or C++20. See the [3]C++ notes
below for more details.
* The deprecated Profile Mode and array_allocator extensions have
been removed from libstdc++.
* The non-standard std::__is_nullptr_t type trait is deprecated and
will be removed from libstdc++ in a future release. The standard
trait std::is_null_pointer should be instead.
* The minimum version of the [4]MPFR library required for building
GCC has been increased to version 3.1.0 (released 2011-10-03).
* The automatic template instantiation at link time (-frepo) has been
removed.
* The --param allow-store-data-races internal parameter has been
removed in favor of a new official option -fallow-store-data-races.
While default behavior is unchanged and the new option allows to
correctly maintain a per compilation unit setting across link-time
optimization, alteration of the default via --param
allow-store-data-races will now be diagnosed and build systems have
to be adjusted accordingly.
* Offloading to Heterogeneous System Architecture Intermediate
Language (HSAIL) has been deprecated and will likely be removed in
a future release.
* The type of the std::iterator base class of
std::istreambuf_iterator was changed in C++98 mode to be consistent
with C++11 and later standards. See the [5]libstdc++ notes below
for more details.
* GCC 10.5 does not bootstrap with a C++98 compiler; if you need to
start from C++98, you should build 10.4 or 9.5 instead.

[6]General Improvements

* New built-in functions:
+ The [7]__has_builtin built-in preprocessor operator can be
used to query support for built-in functions provided by GCC
and other compilers that support it.
+ __builtin_roundeven for the corresponding function from
ISO/IEC TS 18661.
* New command-line options:
+ [8]-fallocation-dce removes unneeded pairs of new and delete
operators.
+ [9]-fprofile-partial-training can now be used to inform the
compiler that code paths not covered by the training run
should not be optimized for size.
+ [10]-fprofile-reproducible controls level of reproducibility
of profile gathered by [11]-fprofile-generate. This makes it
possible to rebuild program with same outcome which is useful,
for example, for distribution packages.
+ [12]-fprofile-prefix-path can be used in combination with
-fprofile-generate=profile_dir and -fprofile-use=profile_dir
to inform GCC where the base directory of build source tree is
in case it differs between instrumentation and optimized
builds.
+ [13]-fanalyzer enables a new static analysis pass and
associated warnings. This pass performs a time-consuming
exploration of paths through the code in the hope of detecting
various common errors, such as double-free bugs. This option
should be regarded as experimental in this release. In
particular, analysis of non-C code is unlikely to work.
* Inter-procedural optimization improvements:
+ The inter-procedural scalar replacement of aggregates
(IPA-SRA) pass was re-implemented to work at link-time and can
now also remove computing and returning unused return values.
+ [14]-finline-functions is now enabled at -O2 and was retuned
for better code size versus runtime performance trade-offs.
Inliner heuristics was also significantly sped up to avoid
negative impact to -flto -O2 compile times.
+ Inliner heuristics and function cloning can now use
value-range information to predict effectivity of individual
transformations.
+ During link-time optimization the C++ One Definition Rule is
used to increase precision of type based alias analysis.
* Link-time optimization improvements:
+ A new binary [15]lto-dump has been added. It dumps various
information about LTO bytecode object files.
+ The parallel phase of the LTO can automatically detect a
running make's jobserver or fall back to number of available
cores.
+ The LTO bytecode can be compressed with the [16]zstd
algorithm. The configure script automatically detects zstd
support.
+ Most --param values can now be specified at translation unit
granularity. This includes all parameters controlling the
inliner and other inter-procedural optimizations. Unlike
earlier releases, GCC 10 will ignore parameters controlling
optimizations specified at link-time and apply parameters
specified at compile-time in the same manner as done for
optimization flags.
* Profile driven optimization improvements:
+ Profile maintenance during compilation and hot/cold code
partitioning have been improved.
+ Using [17]-fprofile-values, an instrumented binary can track
multiple values (up to 4) for e.g. indirect calls and provide
more precise profile information.

[18]New Languages and Language-Specific Improvements

* Version 2.6 of the [19]OpenACC specification is now supported by
the C, C++ and Fortran compilers. See the [20]implementation status
section on the OpenACC wiki page and the [21]run-time library
documentation for further information.
* GCC 10 adds a number of newly implemented [22]OpenMP 5.0 features
such as conditional lastprivate clause, scan and loop directives,
order(concurrent) and use_device_addr clauses support, if clause on
simd construct, and partial support for the declare variant
directive, getting closer to full support of the OpenMP 5.0
standard.
* OpenMP and OpenACC now support [23]offloading to AMD Radeon (GCN)
GPUs; supported are the third-generation Fiji (fiji) and the
fifth-generation VEGA 10/VEGA 20 (gfx900 or gfx906).

[24]C family

* New attributes:
+ The access function and type attribute has been added to
describe how a function accesses objects passed to it by
pointer or reference, and to associate such arguments with
integer arguments denoting the objects' sizes. The attribute
is used to enable the detection of invalid accesses by
user-defined functions, such as those diagnosed by
-Wstringop-overflow.
+ The symver attribute can be used to bind symbols to specific
version nodes on ELF platforms. This is preferred to using
inline assembly with GNU as symver directive because the
latter is not compatible with link-time optimizations.
* New warnings:
+ [25]-Wstring-compare, enabled by -Wextra, warns about equality
and inequality expressions between zero and the result of a
call to either strcmp and strncmp that evaluate to a constant
as a result of the length of one argument being greater than
the size of the array pointed to by the other.
+ [26]-Wzero-length-bounds, enabled by -Warray-bounds, warns
about accesses to elements of zero-length arrays that might
overlap other members of the same object.
* Enhancements to existing warnings:
+ [27]-Warray-bounds detects more out-of-bounds accesses to
member arrays as well as accesses to elements of zero-length
arrays.
+ [28]-Wformat-overflow makes full use of string length
information computed by the strlen optimization pass.
+ [29]-Wrestrict detects overlapping accesses to dynamically
allocated objects.
+ [30]-Wreturn-local-addr diagnoses more instances of return
statements returning addresses of automatic variables.
+ [31]-Wstringop-overflow detects more out-of-bounds stores to
member arrays including zero-length arrays, dynamically
allocated objects and variable length arrays, as well as more
instances of reads of unterminated character arrays by string
built-in functions. The warning also detects out-of-bounds
accesses by calls to user-defined functions declared with the
new attribute access.
+ [32]-Warith-conversion re-enables warnings from -Wconversion,
-Wfloat-conversion, and -Wsign-conversion that are now off by
default for an expression where the result of an arithmetic
operation will not fit in the target type due to promotion,
but the operands of the expression do fit in the target type.
* Extended characters in identifiers may now be specified directly in
the input encoding (UTF-8, by default), in addition to the UCN
syntax (\uNNNN or \UNNNNNNNN) that is already supported:

static const int p = 3;
int get_na�ve_pi() {
return p;
}

[33]C

* Several new features from the upcoming C2X revision of the ISO C
standard are supported with -std=c2x and -std=gnu2x. Some of these
features are also supported as extensions when compiling for older
language versions. In addition to the features listed, some
features previously supported as extensions and now added to the C
standard are enabled by default in C2X mode and not diagnosed with
-std=c2x -Wpedantic.
+ The [[]] attribute syntax is supported, as in C++. Existing
attributes can be used with this syntax in forms such as
[[gnu::const]]. The standard attributes [[deprecated]],
[[fallthrough]] and [[maybe_unused]] are supported.
+ UTF-8 character constants using the u8'' syntax are supported.
+ <float.h> defines macros FLT_NORM_MAX, DBL_NORM_MAX and
LDBL_NORM_MAX.
+ When decimal floating-point arithmetic is supported, <float.h>
defines macros DEC32_TRUE_MIN, DEC64_TRUE_MIN and
DEC128_TRUE_MIN, in addition to the macros that were
previously only defined if __STDC_WANT_DEC_FP__ was defined
before including <float.h>.
+ In C2X mode, empty parentheses in a function definition give
that function a type with a prototype for subsequent calls;
other old-style function definitions are diagnosed by default
in C2X mode.
+ The strftime format checking supports the %OB and %Ob formats.
+ In C2X mode, -fno-fp-int-builtin-inexact is enabled by
default.
* GCC now defaults to -fno-common. As a result, global variable
accesses are more efficient on various targets. In C, global
variables with multiple tentative definitions now result in linker
errors. With -fcommon such definitions are silently merged during
linking.

[34]C++

* Several C++20 features have been implemented:
+ Concepts, including P0734R0, P0857R0, P1084R2, P1141R2,
P0848R3, P1616R1, P1452R2
+ P1668R1, Permitting Unevaluated inline-assembly in constexpr
Functions
+ P1161R3, Deprecate a[b,c]
+ P0848R3, Conditionally Trivial Special Member Functions
+ P1091R3, Extending structured bindings
+ P1143R2, Adding the constinit keyword
+ P1152R4, Deprecating volatile
+ P0388R4, Permit conversions to arrays of unknown bound
+ P0784R7, constexpr new
+ P1301R4, [[nodiscard("with reason")]]
+ P1814R0, class template argument deduction for alias templates
+ P1816R0, class template argument deduction for aggregates
+ P0960R3, Parenthesized initialization of aggregates
+ P1331R2, Allow trivial default initialization in constexpr
contexts
+ P1327R1, Allowing dynamic_cast and polymorphic typeid in
constexpr contexts
+ P0912R5, Coroutines (requires -fcoroutines)
* Several C++ Defect Reports have been resolved, e.g.:
+ DR 1560, lvalue-to-rvalue conversion in ?:
+ DR 1813, __is_standard_layout for a class with repeated bases
+ DR 2094, volatile scalars are trivially copyable,
+ DR 2096, constraints on literal unions
+ DR 2413, typename in conversion-function-ids
+ DR 2352, Similar types and reference binding
+ DR 1601, Promotion of enumeration with fixed underlying type
+ DR 330, Qualification conversions and pointers to arrays of
pointers
+ DR 1307, Overload resolution based on size of array
initializer-list
+ DR 1710, Missing template keyword in class-or-decltype
* New warnings:
+ [35]-Wmismatched-tags, disabled by default, warns about
declarations of structs, classes, and class templates and
their specializations with a class-key that does not match
either the definition or the first declaration if no
definition is provided. The option is provided to ease
portability to Windows-based compilers.
+ [36]-Wredundant-tags, disabled by default, warns about
redundant class-key and enum-key in contexts where the key can
be eliminated without causing an syntactic ambiguity.
* G++ can now detect modifying constant objects in constexpr
evaluation (which is undefined behavior).
* G++ no longer emits bogus -Wsign-conversion warnings with explicit
casts.
* Narrowing is now detected in more contexts (e.g., case values).
* Memory consumption of the compiler has been reduced in constexpr
evaluation.
* The noexcept-specifier is now properly treated as a complete-class
context as per [class.mem].
* The attribute deprecated can now be used on namespaces too.
* The ABI of passing and returning certain C++ classes by value
changed on several targets in GCC 10, including [37]AArch64,
[38]ARM, [39]PowerPC ELFv2, [40]S/390 and [41]Itanium. These
changes affect classes with a zero-sized subobject (an empty base
class, or data member with the [[no_unique_address]] attribute)
where all other non-static data members have the same type (this is
called a "homogeneous aggregate" in some ABI specifications, or if
there is only one such member, a "single element"). In -std=c++17
and -std=c++20 modes, classes with an empty base class were not
considered to have a single element or to be a homogeneous
aggregate, and so could be passed differently (in the wrong
registers or at the wrong stack address). This could make code
compiled with -std=c++17 and -std=c++14 ABI incompatible. This has
been corrected and the empty bases are ignored in those ABI
decisions, so functions compiled with -std=c++14 and -std=c++17 are
now ABI compatible again. Example: struct empty {}; struct S :
empty { float f; }; void f(S);. Similarly, in classes containing
non-static data members with empty class types using the C++20
[[no_unique_address]] attribute, those members weren't ignored in
the ABI argument passing decisions as they should be. Both of these
ABI changes are now diagnosed with -Wpsabi.

[42]Runtime Library (libstdc++)

* Improved experimental C++2a support, including:
+ Library concepts in <concepts> and <iterator>.
+ Constrained algorithms in <ranges>, <algorithm>, and <memory>
(thanks to Patrick Palka).
+ New algorithms shift_left and shift_right (thanks to Patrick
Palka).
+ std::span (thanks to JeanHeyd Meneide).
+ Three-way comparisons in <compare> and throughout the library.
+ Constexpr support in <algorithm> and elsewhere (thanks to
Edward Smith-Rowland).
+ <stop_token> and std::jthread (thanks to Thomas Rodgers).
+ std::atomic_ref and std::atomic<floating point>.
+ Integer comparison functions (cmp_equal, cmp_less etc.).
+ std::ssize, std::to_array.
+ std::construct_at, std::destroy, constexpr std::allocator.
+ Mathematical constants in <numbers>.
* Support for RDSEED in std::random_device.
* Reduced header dependencies, leading to faster compilation for some
code.
* The std::iterator base class of std::istreambuf_iterator was
changed in C++98 mode to be consistent with C++11 and later
standards. This is expected to have no noticeable effect except in
the unlikely case of a class which has potentially overlapping
subobjects of type std::istreambuf_iterator<C> and another iterator
type with a std::iterator<input_iterator_tag, C, ...> base class.
The layout of such a type might change when compiled as C++98.
[43]Bug 92285 has more details and concrete examples.

[44]D

* Support for static foreach has been implemented.
* Aliases can now be created directly from any __traits that return
symbols or tuples. Previously, an AliasSeq was necessary in order
to alias their return.
* It is now possible to detect the language ABI specified for a
struct, class, or interface using __traits(getLinkage, ...).
* Support for core.math.toPrec intrinsics has been added. These
intrinsics guarantee the rounding to specific floating-point
precisions at specified points in the code.
* Support for pragma(inline) has been implemented. Previously the
pragma was recognized, but had no effect on the compilation.
* Optional parentheses in asm operands are deprecated and will be
removed in a future release.
* All content imported files are now included in the make dependency
list when compiling with -M.
* Compiler recognized attributes provided by the gcc.attribute module
will now take effect when applied to function prototypes as well as
when applied to full function declarations.
* Added a --enable-libphobos-checking configure option to control
whether run-time checks are compiled into the D runtime library.
* Added a --with-libphobos-druntime-only configure option to indicate
whether to build only the core D runtime library, or both the core
and standard libraries into libphobos.

[45]Fortran

* use_device_addr of version 5.0 of the [46]OpenMP specification is
now supported. Note that otherwise OpenMP 4.5 is partially
supported in the Fortran compiler; the largest missing item is
structure element mapping.
* The default buffer size for I/O using unformatted files has been
increased to 1048576. The buffer size for can now be set at runtime
via the environment variables GFORTRAN_FORMATTED_BUFFER_SIZE and
GFORTRAN_UNFORMATTED_BUFFER_SIZE for formatted and unformatted
files, respectively.
* Mismatches between actual and dummy argument lists in a single file
are now rejected with an error. Use the new option
-fallow-argument-mismatch to turn these errors into warnings; this
option is implied with -std=legacy. -Wargument-mismatch has been
removed.
* The handling of a BOZ literal constant has been reworked to provide
better conformance to the Fortran 2008 and 2018 standards. In these
Fortran standards, a BOZ literal constant is a typeless and
kindless entity. As a part of the rework, documented and
undocumented extensions to the Fortran standard now emit errors
during compilation. Some of these extensions are permitted with the
-fallow-invalid-boz option, which degrades the error to a warning
and the code is compiled as with older gfortran.
* At any optimization level except-Os, gfortran now uses inline
packing for arguments instead of calling a library routine. If the
source contains a large number of arguments that need to be
repacked, code size or time for compilation can become excessive.
If that is the case, -fno-inline-arg-packing can be used to disable
inline argument packing.
* Legacy extensions:
+ For formatted input/output, if the explicit widths after the
data-edit descriptors I, F and G have been omitted, default
widths are used.
+ A blank format item at the end of a format specification, i.e.
nothing following the final comma, is allowed. Use the option
-fdec-blank-format-item; this option is implied with -fdec.
+ The existing support for AUTOMATIC and STATIC attributes has
been extended to allow variables with the AUTOMATIC attribute
to be used in EQUIVALENCE statements. Use -fdec-static; this
option is implied by -fdec.
+ Allow character literals in assignments and DATA statements
for numeric (INTEGER, REAL, or COMPLEX) or LOGICAL variables.
Use the option -fdec-char-conversions; this option is implied
with -fdec.
+ DEC comparisons, i.e. allow Hollerith constants to be used in
comparisons with INTEGER, REAL, COMPLEX and CHARACTER
expressions. Use the option -fdec.
* Character type names in errors and warnings now include len in
addition to kind; * is used for assumed length. The kind is omitted
if it is the default kind. Examples: CHARACTER(12), CHARACTER(6,4).
* CO_BROADCAST now supports derived type variables including objects
with allocatable components. In this case, the optional arguments
STAT= and ERRMSG= are currently ignored.
* The handling of module and submodule names has been reworked to
allow the full 63-character length mandated by the standard.
Previously symbol names were truncated if the combined length of
module, submodule, and function name exceeded 126 characters. This
change therefore breaks the ABI, but only for cases where this 126
character limit was exceeded.

[47]Go

* GCC 10 provides a complete implementation of the Go 1.14.6 user
packages.

[48]libgccjit

* The libgccjit API gained four new entry points:
+ [49]gcc_jit_version_major, [50]gcc_jit_version_minor, and
[51]gcc_jit_version_patchlevel for programmatically checking
the libgccjit version from client code, and
+ [52]gcc_jit_context_new_bitfield

[53]New Targets and Target Specific Improvements

[54]AArch64 & arm

* The AArch64 and arm ports now support condition flag output
constraints in inline assembly, as indicated by the
__GCC_ASM_FLAG_OUTPUTS__. On arm this feature is only available for
A32 and T32 targets. Please refer to the documentation for more
details.

[55]AArch64

* There have been several improvements related to the Scalable Vector
Extension (SVE):
+ The SVE ACLE types and intrinsics are now supported. They can
be accessed using the header file arm_sve.h.
+ It is now possible to create fixed-length SVE types using the
arm_sve_vector_bits attribute. For example:
#if __ARM_FEATURE_SVE_BITS==512
typedef svint32_t vec512 __attribute__((arm_sve_vector_bits(512)));
typedef svbool_t pred512 __attribute__((arm_sve_vector_bits(512)));
#endif
+ -mlow-precision-div, -mlow-precision-sqrt and
-mlow-precision-recip-sqrt now work for SVE.
+ -msve-vector-bits=128 now generates vector-length-specific
code for little-endian targets. It continues to generate
vector-length-agnostic code for big-endian targets, just as
previous releases did for all targets.
+ The vectorizer is now able to use extending loads and
truncating stores, including gather loads and scatter stores.
+ The vectorizer now compares the cost of vectorizing with SVE
and vectorizing with Advanced SIMD and tries to pick the best
one. Previously it would always use SVE if possible.
+ If a vector loop uses Advanced SIMD rather than SVE, the
vectorizer now considers using SVE to vectorize the left-over
elements (the "scalar tail" or "epilog").
+ Besides these specific points, there have been many general
improvements to the way that the vectorizer uses SVE.
* The -mbranch-protection=pac-ret option now accepts the optional
argument +b-key extension to perform return address signing with
the B-key instead of the A-key.
* The option -moutline-atomics has been added to aid deployment of
the Large System Extensions (LSE) on GNU/Linux systems built with a
baseline architecture targeting Armv8-A. When the option is
specified code is emitted to detect the presence of LSE
instructions at runtime and use them for standard atomic
operations. For more information please refer to the documentation.
* The Transactional Memory Extension is now supported through ACLE
intrinsics. It can be enabled through the +tme option extension
(for example, -march=armv8.5-a+tme).
* A number of features from Armv8.5-A are now supported through ACLE
intrinsics. These include:
+ The random number instructions that can be enabled through the
(already present in GCC 9.1) +rng option extension.
+ Floating-point intrinsics to round to integer instructions
from Armv8.5-A when targeting -march=armv8.5-a or later.
+ Memory Tagging Extension intrinsics enabled through the
+memtag option extension.
* Similarly, the following Armv8.6-A features are now supported
through ACLE intrinsics:
+ The bfloat16 extension. This extension is enabled
automatically when Armv8.6-A is selected (such as by
-march=armv8.6-a). It can also be enabled for Armv8.2-A and
later using the +bf16 option extension.
+ The Matrix Multiply extension. This extension is split into
three parts, one for each supported data type:
o Support for 8-bit integer matrix multiply instructions.
This extension is enabled automatically when Armv8.6-A is
selected. It can also be enabled for Armv8.2-A and later
using the +i8mm option extension.
o Support for 32-bit floating-point matrix multiply
instructions. This extension can be enabled using the
+f32mm option extension, which also has the effect of
enabling SVE.
o Support for 64-bit floating-point matrix multiply
instructions. This extension can be enabled using the
+f64mm option extension, which likewise has the effect of
enabling SVE.
* SVE2 is now supported through ACLE intrinsics and (to a limited
extent) through autovectorization. It can be enabled through the
+sve2 option extension (for example, -march=armv8.5-a+sve2).
Additional extensions can be enabled through +sve2-sm4, +sve2-aes,
+sve2-sha3 and +sve2-bitperm.
* Support has been added for the following processors (GCC
identifiers in parentheses):
+ Arm Cortex-A77 (cortex-a77).
+ Arm Cortex-A76AE (cortex-a76ae).
+ Arm Cortex-A65 (cortex-a65).
+ Arm Cortex-A65AE (cortex-a65ae).
+ Arm Cortex-A34 (cortex-a34).
+ Marvell ThunderX3 (thunderx3t110).
The GCC identifiers can be used as arguments to the -mcpu or -mtune
options, for example: -mcpu=cortex-a77 or -mtune=cortex-a65ae or as
arguments to the equivalent target attributes and pragmas.

[56]arm

* Support for the FDPIC ABI has been added. It uses 64-bit function
descriptors to represent pointers to functions, and enables code
sharing on MMU-less systems. The corresponding target triple is
arm-uclinuxfdpiceabi, and the C library is uclibc-ng.
* Support has been added for the Arm EABI on NetBSD through the
arm*-*-netbsdelf-*eabi* triplet.
* The handling of 64-bit integer operations has been significantly
reworked and improved leading to improved performance and reduced
stack usage when using 64-bit integral data types. The option
-mneon-for-64bits is now deprecated and will be removed in a future
release.
* Support has been added for the following processors (GCC
identifiers in parentheses):
+ Arm Cortex-A77 (cortex-a77).
+ Arm Cortex-A76AE (cortex-a76ae).
+ Arm Cortex-M35P (cortex-m35p).
+ Arm Cortex-M55 (cortex-m55).
The GCC identifiers can be used as arguments to the -mcpu or -mtune
options, for example: -mcpu=cortex-a77 or -mtune=cortex-m35p.
* Support has been extended for the ACLE [57]data-processing
intrinsics to include 32-bit SIMD, saturating arithmetic, 16-bit
multiplication and other related intrinsics aimed at DSP algorithm
optimization.
* Support for -mpure-code in Thumb-1 (v6m) has been added: this
M-profile feature is no longer restricted to targets with MOVT. For
example, -mcpu=cortex-m0 now supports this option.
* Support for the [58]Armv8.1-M Mainline Architecture has been added.
+ Armv8.1-M Mainline can be enabled by using the
-march=armv8.1-m.main command-line option.
* Support for the [59]MVE beta ACLE intrinsics has been added. These
intrinsics can be enabled by including the arm_mve.h header file
and passing the +mve or +mve.fp option extensions (for example:
-march=armv8.1-m.main+mve).
* Support for the Custom Datapath Extension beta ACLE [60]intrinsics
has been added.
* Support for Armv8.1-M Mainline Security Extensions architecture has
been added. The -mcmse option, when used in combination with an
Armv8.1-M Mainline architecture (for example: -march=armv8.1-m.main
-mcmse), now leads to the generation of improved code sequences
when changing security states.

[61]AMD Radeon (GCN)

* Code generation and in particular vectorization support have been
much improved.

[62]ARC

* The interrupt service routine functions save all used registers,
including extension registers and auxiliary registers used by Zero
Overhead Loops.
* Improve code size by using multiple short instructions instead of a
single long mov or ior instruction when its long immediate constant
is known.
* Fix usage of the accumulator register for ARC600.
* Fix issues with uncached attribute.
* Remove -mq-class option.
* Improve 64-bit integer addition and subtraction operations.

[63]AVR

* Support for the XMEGA-like devices

ATtiny202, ATtiny204, ATtiny402, ATtiny404, ATtiny406, ATtiny804,
ATtiny806, ATtiny807, ATtiny1604, ATtiny1606, ATtiny1607, ATmega808,
ATmega809, ATmega1608, ATmega1609, ATmega3208, ATmega3209,
ATmega4808, ATmega4809
has been added.
* A new command-line option -nodevicespecs has been added. It allows
to provide a custom device-specs file by means of

avr-gcc -nodevicespecs -specs=my-spec-file <options>
and without the need to provide options -B and -mmcu=. See [64]AVR
command-line options for details. This feature is also available in
GCC 9.3+ and GCC 8.4+.
* New command-line options -mdouble=[32,64] and -mlong-double=[32,64]
have been added. They allow to choose the size (in bits) of the
double and long double types, respectively. Whether or not the
mentioned layouts are available, whether the options act as a
multilib option, and the default for either option are controlled
by the new [65]AVR configure options --with-double= and
--with-long-double=.
* A new configure option --with-libf7= has been added. It controls to
which level avr-libgcc provides 64-bit floating point support by
means of [66]Libf7.
* A new configure option --with-double-comparison= has been added.
It's unlikely you need to set this option by hand.

[67]IA-32/x86-64

* Support to expand __builtin_roundeven into the appropriate SSE 4.1
instruction has been added.
* New ISA extension support for Intel ENQCMD was added to GCC. ENQCMD
intrinsics are available via the -menqcmd compiler switch.
* GCC now supports the Intel CPU named Cooperlake through
-march=cooperlake. The switch enables the AVX512BF16 ISA
extensions.
* GCC now supports the Intel CPU named Tigerlake through
-march=tigerlake. The switch enables the MOVDIRI MOVDIR64B
AVX512VP2INTERSECT ISA extensions.

[68]MIPS

* The mips*-*-linux* targets now mark object files with appropriate
GNU-stack note, facilitating use of non-executable stack hardening
on GNU/Linux. The soft-float targets have this feature enabled by
default, while for hard-float targets it is required for GCC to be
configured with --with-glibc-version=2.31 against glibc 2.31 or
later.

[69]PowerPC / PowerPC64 / RS6000

* Many vector builtins have been listed as deprecated in the
[70]64-Bit ELF V2 ABI Specification for quite a number of years.
The vector builtins listed in Tables A.8 through A.10 are now
deprecated for GCC 10, and will likely be removed from support in
GCC 11. Note that this does not result in any loss of function.
These deprecated builtins generally provide somewhat nonsensical
argument lists (for example, mixing signed, unsigned, and bool
vector arguments arbitrarily), or are duplicate builtins that are
inconsistent with the expected naming scheme. We expect that this
will be unlikely to affect much if any code, and any required code
changes will be trivial.

[71]PRU

* A new back end targeting TI PRU I/O processors has been contributed
to GCC.

[72]RISC-V

* The riscv*-*-* targets now require GNU binutils version 2.30 or
later, to support new assembly instructions produced by GCC.

[73]V850

* The ABI for V850 nested functions has been changed. Previously the
V850 port used %r20 for the static chain pointer, now the port uses
%r19. This corrects a long standing latent bug in the v850 port
where a call to a nested function would unexpectedly change the
value in %r20.

[74]Operating Systems

[75]Improvements for plugin authors

* GCC diagnostics can now have a chain of events associated with
them, describing a path through the code that triggers the problem.
These can be printed by the diagnostics subsystem in various ways,
controlled by the [76]-fdiagnostics-path-format option, or captured
in JSON form via [77]-fdiagnostics-format=json.
* GCC diagnostics can now be associated with [78]CWE weakness
identifiers, which will appear on the standard error stream, and in
the JSON output from [79]-fdiagnostics-format=json.

Other significant improvements

* To allow inline expansion of both memcpy and memmove, the existing
movmem instruction patterns used for non-overlapping memory copies
have been renamed to cpymem. The movmem name is now used for
overlapping memory moves, consistent with the library functions
memcpy and memmove.
* For many releases, when GCC emits a warning it prints the option
controlling that warning. As of GCC 10, that option text is now a
clickable hyperlink for the documentation of that option (assuming
a [80]sufficiently capable terminal). This behavior can be
controlled via a new [81]-fdiagnostics-urls option (along with
various environment variables and heuristics documented with that
option).

GCC 10.1

This is the [82]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 10.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[83]GCC 10.2

This is the [84]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 10.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[85]GCC 10.3

This is the [86]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 10.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Target Specific Changes

AArch64

* A bug with the Random Number intrinsics in the arm_acle.h header
that resulted in an incorrect status result being returned has been
fixed.
* GCC now supports the Fujitsu A64FX. The associated -mcpu and -mtune
options are -mcpu=a64fx and -mtune=a64fx respectively. In
particular, -mcpu=a64fx generates code for Armv8.2-A with SVE and
tunes the code for the A64FX. This includes tuning the SVE code,
although by default the code is still length-agnostic and so works
for all SVE implementations. Adding -msve-vector-bits=512 makes the
code specific to 512-bit SVE.

x86-64

* GCC 10.3 supports AMD CPUs based on the znver3 core via
-march=znver3.

[87]GCC 10.4

This is the [88]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 10.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Target Specific Changes

x86-64

* The x86-64 ABI of passing and returning structures with a 64-bit
integer vector changed in GCC 10.1 when MMX is disabled. Disabling
MMX no longer changes how they are passed nor returned. This ABI
change is now diagnosed with -Wpsabi.

[89]GCC 10.5

This is the [90]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 10.5 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

For questions related to the use of GCC, please consult these web
pages and the [91]GCC manuals. If that fails, the
[92][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [93][email protected]. All of [94]our lists have public
archives.

Copyright (C) [95]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [96]maintained by the GCC team. Last modified
2025-03-21.

References

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13. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Static-Analyzer-Options.html
14. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Optimize-Options.html#index-finline-functions
15. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/lto-dump.html
16. https://facebook.github.io/zstd/
17. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Optimize-Options.html#index-fprofile-values
18. https://gcc.gnu.org/gcc-10/changes.html#languages
19. https://www.openacc.org/
20. https://gcc.gnu.org/wiki/OpenACC/Implementation%20Status#status-10
21. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/libgomp/#toc-Enabling-OpenACC-1
22. https://www.openmp.org/specifications/
23. https://gcc.gnu.org/wiki/Offloading
24. https://gcc.gnu.org/gcc-10/changes.html#c-family
25. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Wstring-compare
26. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Wzero-length-bounds
27. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Warray-bounds
28. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Wformat-overflow
29. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Wrestrict
30. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Wreturn-local-addr
31. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Wstringop-overflow
32. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Warning-Options.html#index-Warith-conversion
33. https://gcc.gnu.org/gcc-10/changes.html#c
34. https://gcc.gnu.org/gcc-10/changes.html#cxx
35. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/C_002b_002b-Dialect-Options.html#index-Wmismatched-tags
36. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/C_002b_002b-Dialect-Options.html#index-Wredundant-tags
37. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94383
38. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94711
39. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94707
40. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94704
41. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94706
42. https://gcc.gnu.org/gcc-10/changes.html#libstdcxx
43. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92285
44. https://gcc.gnu.org/gcc-10/changes.html#d
45. https://gcc.gnu.org/gcc-10/changes.html#fortran
46. https://www.openmp.org/specifications/
47. https://gcc.gnu.org/gcc-10/changes.html#go
48. https://gcc.gnu.org/gcc-10/changes.html#jit
49. https://gcc.gnu.org/onlinedocs/jit/topics/compatibility.html#c.gcc_jit_version_major
50. https://gcc.gnu.org/onlinedocs/jit/topics/compatibility.html#c.gcc_jit_version_minor
51. https://gcc.gnu.org/onlinedocs/jit/topics/compatibility.html#c.gcc_jit_version_patchlevel
52. https://gcc.gnu.org/onlinedocs/jit/topics/types.html#c.gcc_jit_context_new_bitfield
53. https://gcc.gnu.org/gcc-10/changes.html#targets
54. https://gcc.gnu.org/gcc-10/changes.html#arm-targets
55. https://gcc.gnu.org/gcc-10/changes.html#aarch64
56. https://gcc.gnu.org/gcc-10/changes.html#arm
57. https://developer.arm.com/documentation/101028/0009/Data-processing-intrinsics
58. https://developer.arm.com/Architectures/M-Profile%20Architecture
59. https://developer.arm.com/architectures/instruction-sets/intrinsics/
60. https://developer.arm.com/documentation/101028/0010/Custom-Datapath-Extension
61. https://gcc.gnu.org/gcc-10/changes.html#amdgcn
62. https://gcc.gnu.org/gcc-10/changes.html#arc
63. https://gcc.gnu.org/gcc-10/changes.html#avr
64. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/AVR-Options.html#index-nodevicespecs
65. https://gcc.gnu.org/install/configure.html#avr
66. https://gcc.gnu.org/wiki/avr-gcc#Libf7
67. https://gcc.gnu.org/gcc-10/changes.html#x86
68. https://gcc.gnu.org/gcc-10/changes.html#mips
69. https://gcc.gnu.org/gcc-10/changes.html#powerpc
70. https://openpowerfoundation.org/?resource_lib=64-bit-elf-v2-abi-specification-power-architecture
71. https://gcc.gnu.org/gcc-10/changes.html#pru
72. https://gcc.gnu.org/gcc-10/changes.html#riscv
73. https://gcc.gnu.org/gcc-10/changes.html#v850
74. https://gcc.gnu.org/gcc-10/changes.html#os
75. https://gcc.gnu.org/gcc-10/changes.html#plugins
76. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Diagnostic-Message-Formatting-Options.html#index-fdiagnostics-path-format
77. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Diagnostic-Message-Formatting-Options.html#index-fdiagnostics-format
78. https://cwe.mitre.org/
79. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Diagnostic-Message-Formatting-Options.html#index-fdiagnostics-format
80. https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda
81. https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Diagnostic-Message-Formatting-Options.html#index-fdiagnostics-urls
82. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=10.0
83. https://gcc.gnu.org/gcc-10/changes.html#GCC10.2
84. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=10.2
85. https://gcc.gnu.org/gcc-10/changes.html#GCC10.3
86. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=10.3
87. https://gcc.gnu.org/gcc-10/changes.html#GCC10.4
88. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=10.4
89. https://gcc.gnu.org/gcc-10/changes.html#GCC10.5
90. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=10.5
91. https://gcc.gnu.org/onlinedocs/
92. mailto:[email protected]
93. mailto:[email protected]
94. https://gcc.gnu.org/lists.html
95. https://www.fsf.org/
96. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-9/index.html

GCC 9 Release Series

(This release series is no longer supported.)

May 27, 2022

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 9.5.

This release is a bug-fix release, containing fixes for regressions in
GCC 9.4 relative to previous releases of GCC.

Release History

GCC 9.5
May 27, 2022 ([2]changes, [3]documentation)

GCC 9.4
June 1, 2021 ([4]changes, [5]documentation)

GCC 9.3
Mar 12, 2020 ([6]changes, [7]documentation)

GCC 9.2
Aug 12, 2019 ([8]changes, [9]documentation)

GCC 9.1
May 3, 2019 ([10]changes, [11]documentation)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [12]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [13]GCC
project web site or contact the [14]GCC development mailing list.

To obtain GCC please use [15]our mirror sites or [16]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [17]GCC manuals. If that fails, the
[18][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [19][email protected]. All of [20]our lists have public
archives.

Copyright (C) [21]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [22]maintained by the GCC team. Last modified
2024-05-30.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-9/changes.html
3. https://gcc.gnu.org/onlinedocs/9.5.0/
4. https://gcc.gnu.org/gcc-9/changes.html
5. https://gcc.gnu.org/onlinedocs/9.4.0/
6. https://gcc.gnu.org/gcc-9/changes.html
7. https://gcc.gnu.org/onlinedocs/9.3.0/
8. https://gcc.gnu.org/gcc-9/changes.html
9. https://gcc.gnu.org/onlinedocs/9.2.0/
10. https://gcc.gnu.org/gcc-9/changes.html
11. https://gcc.gnu.org/onlinedocs/9.1.0/
12. https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gcc/Contributors.html
13. https://gcc.gnu.org/index.html
14. mailto:[email protected]
15. https://gcc.gnu.org/mirrors.html
16. https://gcc.gnu.org/git.html
17. https://gcc.gnu.org/onlinedocs/
18. mailto:[email protected]
19. mailto:[email protected]
20. https://gcc.gnu.org/lists.html
21. https://www.fsf.org/
22. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-9/changes.html

GCC 9 Release Series
Changes, New Features, and Fixes

This page is a "brief" summary of some of the huge number of
improvements in GCC 9. You may also want to check out our [1]Porting to
GCC 9 page and the [2]full GCC documentation.

Caveats

* On Arm targets (arm*-*-*), [3]a bug in the implementation of the
procedure call standard (AAPCS) in the GCC 6, 7 and 8 releases has
been fixed: a structure containing a bit-field based on a 64-bit
integral type and where no other element in a structure required
64-bit alignment could be passed incorrectly to functions. This is
an ABI change. If the option -Wpsabi is enabled (on by default) the
compiler will emit a diagnostic note for code that might be
affected.
* Support for a number of older systems and recently unmaintained or
untested target ports of GCC has been declared obsolete in GCC 9.
Unless there is activity to revive them, the next release of GCC
will have their sources permanently removed.
The following ports for individual systems on particular
architectures have been obsoleted:
+ Solaris 10 (*-*-solaris2.10). Details can be found in the
[4]announcement.
+ Cell Broadband Engine SPU (spu*-*-*). Details can be found in
the [5]announcement.
* A change to the C++ std::rotate algorithm in GCC 9.1.0 can cause
ABI incompatibilities with object files compiled with other
versions of GCC. If the std::rotate algorithm is called with an
empty range then it might cause a divide-by-zero error (as a SIGFPE
signal) and crash. The change has been reverted for GCC 9.2.0 and
future releases. For more details see [6]Bug 90920. The problem can
be avoided by recompiling any objects that might call std::rotate
with an empty range, so that the GCC 9.1.0 definition of
std::rotate is not used.
* The automatic template instantiation at link time ([7]-frepo) has
been deprecated and will be removed in a future release.
* The --with-default-libstdcxx-abi=gcc4-compatible configure option
is broken in the 9.1 and 9.2 releases, producing a shared library
with missing symbols (see [8]Bug 90361). As a workaround, configure
without that option and build GCC as normal, then edit the
installed <bits/c++config.h> headers to define the
_GLIBCXX_USE_CXX11_ABI macro to 0.

[9]General Improvements

The following GCC command line options have been introduced or
improved.
* All command line options that take a byte-size argument accept
64-bit integers as well as standard SI and IEC suffixes such as kb
and KiB, MB and MiB, or GB and GiB denoting the corresponding
multiples of bytes. See [10]Invoking GCC for more.
* A new option [11]-flive-patching=[inline-only-static|inline-clone]
generates code suitable for live patching. At the same time it
provides multiple-level control over IPA optimizations. See the
user guide for more details.
* A new option, --completion, has been added to provide more fine
option completion in a shell. It is intended to be used by
Bash-completion.
* GCC's diagnostics now print source code with a left margin showing
line numbers, configurable with
[12]-fno-diagnostics-show-line-numbers.
GCC's diagnostics can also now label regions of the source code to
show pertinent information, such as the types within an expression.
$ g++ t.cc
t.cc: In function 'int test(const shape&, const shape&)':
t.cc:15:4: error: no match for 'operator+' (operand types are 'boxed_value<doubl
e>' and 'boxed_value<double>')
14 | return (width(s1) * height(s1)
| ~~~~~~~~~~~~~~~~~~~~~~
| |
| boxed_value<[...]>
15 | + width(s2) * height(s2));
| ^ ~~~~~~~~~~~~~~~~~~~~~~
| |
| boxed_value<[...]>

These labels can be disabled via [13]-fno-diagnostics-show-labels.
* A new option [14]-fdiagnostics-format=json has been introduced for
emitting diagnostics in a machine-readable format.
* The alignment-related options [15]-falign-functions,
[16]-falign-labels, [17]-falign-loops, and [18]-falign-jumps
received support for a secondary alignment (e.g.
-falign-loops=n:m:n2:m2).
* New pair of profiling options ([19]-fprofile-filter-files and
[20]-fprofile-exclude-files) has been added. The options help to
filter which source files are instrumented.
* AddressSanitizer generates more compact redzones for automatic
variables. That helps to reduce memory footprint of a sanitized
binary.
* Numerous improvements have been made to the output of
[21]-fopt-info.
Messages are now prefixed with optimized, missed, or note, rather
than the old behavior of all being prefixed with note.
The output from -fopt-info can now contain information on inlining
decisions:
$ g++ -c inline.cc -O2 -fopt-info-inline-all
inline.cc:24:11: note: Considering inline candidate void foreach(T, T, void (*)(
E)) [with T = char**; E = char*]/2.
inline.cc:24:11: optimized: Inlining void foreach(T, T, void (*)(E)) [with T =
char**; E = char*]/2 into int main(int, char**)/1.
inline.cc:19:12: missed: not inlinable: void inline_me(char*)/0 -> int std::pu
ts(const char*)/3, function body not available
inline.cc:13:8: optimized: Inlined void inline_me(char*)/4 into int main(int, c
har**)/1 which now has time 127.363637 and size 11, net change of +0.
Unit growth for small function inlining: 16->16 (0%)

Inlined 2 calls, eliminated 1 functions

The output from the vectorizer has been rationalized so that failed
attempts to vectorize a loop are displayed in the form
[LOOP-LOCATION]: couldn't vectorize this loop
[PROBLEM-LOCATION]: because of [REASON]

rather than an exhaustive log of all decisions made by the
vectorizer. For example:
$ gcc -c v.c -O3 -fopt-info-all-vec
v.c:7:3: missed: couldn't vectorize loop
v.c:10:7: missed: statement clobbers memory: __asm__ __volatile__("" : : : "me
mory");
v.c:3:6: note: vectorized 0 loops in function.
v.c:10:7: missed: statement clobbers memory: __asm__ __volatile__("" : : : "me
mory");

The old behavior can be obtained via a new -internals suboption of
-fopt-info.
* A new option, [22]-fsave-optimization-record has been added, which
writes a SRCFILE.opt-record.json.gz file describing the
optimization decisions made by GCC. This is similar to the output
of -fopt-info, but with additional metadata such as the inlining
chain, and profile information (if available).
* Inter-procedural propagation of stack alignment can now be
controlled by [23]-fipa-stack-alignment.
* Propagation of addressability, readonly, and writeonly flags on
static variables can now be controlled by
[24]-fipa-reference-addressable.

The following built-in functions have been introduced.
* [25]__builtin_expect_with_probability to provide branch prediction
probability hints to the optimizer.
* [26]__builtin_has_attribute determines whether a function, type, or
variable has been declared with some attribute.
* [27]__builtin_speculation_safe_value can be used to help mitigate
against unsafe speculative execution.

The following attributes have been introduced.
* The [28]copy function attribute has been added. The attribute can
also be applied to type definitions and to variable declarations.

A large number of improvements to code generation have been made,
including but not limited to the following.
* Switch expansion has been improved by using a different strategy
(jump table, bit test, decision tree) for a subset of switch cases.
* A linear function expression defined as a switch statement can be
transformed by [29]-ftree-switch-conversion. For example:

int
foo (int how)
{
switch (how) {
case 2: how = 205; break;
case 3: how = 305; break;
case 4: how = 405; break;
case 5: how = 505; break;
case 6: how = 605; break;
}
return how;
}

can be transformed into 100 * how + 5 (for values defined in the
switch statement).
* Inter-procedural optimization improvements:
+ Inliner defaults were tuned to better suit modern C++
codebases, especially when built with link time-optimizations.
New parameters max-inline-insns-small, max-inline-insns-size,
uninlined-function-insns, uninlined-function-time,
uninlined-thunk-insns, and uninlined-thunk-time were added.
+ Hot/cold partitioning is now more precise and aggressive.
+ Improved scalability for very large translation units
(especially when link-time optimizing large programs).
* Profile driven optimization improvements:
+ [30]-fprofile-use now enables [31]-fversion-loops-for-strides,
[32]-floop-interchange, [33]-floop-unroll-and-jam,
[34]-ftree-loop-distribution.
+ Streaming of counter histograms was removed, which reduces the
size of profile files. Histograms are computed on the fly with
link-time optimization.
+ The parameter hot-bb-count-ws-permille was reduced from 999 to
990 to account for more precise histograms.
* Link-time optimization improvements:
+ Types are now simplified prior to streaming resulting in
significant reductions of LTO object file sizes and link-time
memory use as well as improvements of link-time parallelism.
+ The default number of partitions (--param lto-partitions) was
increased from 32 to 128 enabling effective use of CPUs with
more than 32 hyperthreads. --param
lto-max-streaming-parallelism can now be used to control the
number of streaming processes.
+ Warnings on C++ One Decl Rule violations (-Wodr) are now more
informative and produce fewer redundant results.
Overall compile time of Firefox 66 and LibreOffice 6.2.3 on an
8-core machine was reduced by about 5% compared to GCC 8.3, and the
size of LTO object files by 7%. LTO link time improves by 11% on an
8-core machine and scales significantly better for more parallel
build environments. The serial stage of the link-time optimization
is 28% faster consuming 20% less memory. The parallel stage now
scales to up to 128 partitions rather than 32 and reduces memory
use for every worker by 30%.

The following improvements to the gcov command-line utility have been
made.
* The gcov tool received a new option [35]--use-hotness-colors (-q)
that can provide perf-like coloring of hot functions.
* The gcov tool has changed its intermediate format to a new JSON
format.

[36]New Languages and Language specific improvements

[37]OpenACC support in C, C++, and Fortran continues to be maintained
and improved. Most of the OpenACC 2.5 specification is implemented. See
the [38]implementation status section on the OpenACC wiki page for
further information.

[39]C family

* Version 5.0 of the [40]OpenMP specification is now partially
supported in the C and C++ compilers. For details which features of
OpenMP 5.0 are and which are not supported in the GCC 9 release see
[41]this mail.
* New extensions:
+ [42]__builtin_convertvector built-in for vector conversions
has been added.
* New warnings:
+ [43]-Waddress-of-packed-member, enabled by default, warns
about an unaligned pointer value from the address of a packed
member of a struct or union.
* Enhancements to existing warnings:
+ [44]-Warray-bounds detects more instances of out-of-bounds
indices.
+ [45]-Wattribute-alias also detects attribute mismatches
between alias declarations and their targets, in addition to
mismatches between their types.
+ [46]-Wformat-overflow and [47]-Wformat-truncation have been
extended to all formatted input/output functions (where
applicable) and enhanced to detect a subset of instances of
reading past the end of unterminated constant character arrays
in %s directives.
+ [48]-Wmissing-attributes detects instances of missing function
attributes on declarations of aliases and weak references.
+ [49]-Wstringop-truncation also detects a subset of instances
of reading past the end of unterminated constant character
arrays,
* If a macro is used with the wrong argument count, the C and C++
front ends now show the definition of that macro via a note.
* The spelling corrector now considers transposed letters, and the
threshold for similarity has been tightened, to avoid nonsensical
suggestions.

[50]C

* There is now experimental support for -std=c2x, to select support
for the upcoming C2X revision of the ISO C standard. This standard
is in the early stages of development and the only feature
supported in GCC 9 is _Static_assert with a single argument
(support for _Static_assert with two arguments was added in C11 and
GCC 4.6). There are also new options -std=gnu2x, for C2X with GNU
extensions, and -Wc11-c2x-compat, to warn for uses of features
added in C2X (such warnings are also enabled by use of -Wpedantic
if not using -std=c2x or -std=gnu2x).
* New warnings:
+ [51]-Wabsolute-value warns for calls to standard functions
that compute the absolute value of an argument when a more
appropriate standard function is available. For example,
calling abs(3.14) triggers the warning because the appropriate
function to call to compute the absolute value of a double
argument is fabs. The option also triggers warnings when the
argument in a call to such a function has an unsigned type.
This warning can be suppressed with an explicit type cast and
it is also enabled by -Wextra.

[52]C++

* New warnings:
+ [53]-Wdeprecated-copy, implied by -Wextra, warns about the
C++11 deprecation of implicitly declared copy constructor and
assignment operator if one of them is user-provided.
-Wdeprecated-copy-dtor also warns if the destructor is
user-provided, as specified in C++11.
+ [54]-Winit-list-lifetime, on by default, warns about uses of
std::initializer_list that are likely to result in a dangling
pointer, such as returning or assigning from a temporary list.
+ [55]-Wredundant-move, implied by -Wextra, warns about
redundant calls to std::move.
+ [56]-Wpessimizing-move, implied by -Wall, warns when a call to
std::move prevents copy elision.
+ [57]-Wclass-conversion, on by default, warns when a conversion
function will never be called due to the type it converts to.
* The C++ front end has experimental support for some of the upcoming
C++2a draft features with the -std=c++2a or -std=gnu++2a flags,
including range-based for statements with initializer, default
constructible and assignable stateless lambdas, lambdas in
unevaluated contexts, language support for empty data members,
allowing pack expansion in lambda init-capture, likely and unlikely
attributes, class types in non-type template parameters, allowing
virtual function calls in constant expressions, explicit(bool),
std::is_constant_evaluated, nested inline namespaces, etc. For a
full list of new features, see [58]the C++ status page.
* The C++ front end now preserves source locations for literals,
id-expression, and mem-initializer for longer. For example it is
now able to pin-point the pertinent locations for bad
initializations such as these
$ g++ -c bad-inits.cc
bad-inits.cc:10:14: error: cannot convert 'json' to 'int' in initialization
10 | { 3, json::object },
| ~~~~~~^~~~~~
| |
| json
bad-inits.cc:14:31: error: initializer-string for array of chars is too long [-f
permissive]
14 | char buffers[3][5] = { "red", "green", "blue" };
| ^~~~~~~
bad-inits.cc: In constructor 'X::X()':
bad-inits.cc:17:13: error: invalid conversion from 'int' to 'void*' [-fpermissiv
e]
17 | X() : one(42), two(42), three(42)
| ^~
| |
| int

rather than emitting the error at the final closing parenthesis or
brace.
* Error-reporting of overload resolution has been special-cased to
make the case of a single failed candidate easier to read. For
example:
$ g++ param-type-mismatch.cc
param-type-mismatch.cc: In function 'int test(int, const char*, float)':
param-type-mismatch.cc:8:32: error: cannot convert 'const char*' to 'const char*
*'
8 | return foo::member_1 (first, second, third);
| ^~~~~~
| |
| const char*
param-type-mismatch.cc:3:46: note: initializing argument 2 of 'static int foo:
:member_1(int, const char**, float)'
3 | static int member_1 (int one, const char **two, float three);
| ~~~~~~~~~~~~~^~~

highlights both the problematic argument, and the parameter that it
can't be converted to.
* Diagnostics involving binary operators now use color to distinguish
the two operands, and label them separately (as per the example of
source labelling above).
* Diagnostics involving function calls now highlight the pertinent
parameter of the declaration in more places.
$ g++ bad-conversion.cc
bad-conversion.cc: In function 'void caller()':
bad-conversion.cc:9:14: error: cannot convert 'bool' to 'void*'
9 | callee (0, false, 2);
| ^~~~~
| |
| bool
bad-conversion.cc:3:19: note: initializing argument 2 of 'void callee(int, voi
d*, int)'
3 | void callee (int, void *, int)
| ^~~~~~

* The C++ front end's implementation of [59]-Wformat now shows
precise locations within string literals, and underlines the
pertinent arguments at bogus call sites (the C front end has been
doing this since GCC 7). For example:
$ g++ -c bad-printf.cc -Wall
bad-printf.cc: In function 'void print_field(const char*, float, long int, long
int)':
bad-printf.cc:6:17: warning: field width specifier '*' expects argument of type
'int', but argument 3 has type 'long int' [-Wformat=]
6 | printf ("%s: %*ld ", fieldname, column - width, value);
| ~^~~ ~~~~~~~~~~~~~~
| | |
| int long int
bad-printf.cc:6:19: warning: format '%ld' expects argument of type 'long int', b
ut argument 4 has type 'double' [-Wformat=]
6 | printf ("%s: %*ld ", fieldname, column - width, value);
| ~~~^ ~~~~~
| | |
| long int double
| %*f

* The C++ front end has gained new fix-it hints for forgetting the
return *this; needed by various C++ operators:
$ g++ -c operator.cc
operator.cc: In member function 'boxed_ptr& boxed_ptr::operator=(const boxed_ptr
&)':
operator.cc:7:3: warning: no return statement in function returning non-void [-W
return-type]
6 | m_ptr = other.m_ptr;
+++ |+ return *this;
7 | }
| ^

for when the compiler needs a typename:
$ g++ -c template.cc
template.cc:3:3: error: need 'typename' before 'Traits::type' because 'Traits' i
s a dependent scope
3 | Traits::type type;
| ^~~~~~
| typename

when trying to use an accessor member as if it were a data member:
$ g++ -c fncall.cc
fncall.cc: In function 'void hangman(const mystring&)':
fncall.cc:12:11: error: invalid use of member function 'int mystring::get_length
() const' (did you forget the '()' ?)
12 | if (str.get_length > 0)
| ~~~~^~~~~~~~~~
| ()

for C++11's scoped enums:
$ g++ -c enums.cc
enums.cc: In function 'void json::test(const json::value&)':
enums.cc:12:26: error: 'STRING' was not declared in this scope; did you mean 'js
on::kind::STRING'?
12 | if (v.get_kind () == STRING)
| ^~~~~~
| json::kind::STRING
enums.cc:3:44: note: 'json::kind::STRING' declared here
3 | enum class kind { OBJECT, ARRAY, NUMBER, STRING, TRUE, FALSE, NULL_ };
| ^~~~~~

and a tweak to integrate the suggestions about misspelled members
with that for accessors:
$ g++ -c accessor-fixit.cc
accessor-fixit.cc: In function 'int test(t*)':
accessor-fixit.cc:17:15: error: 'class t' has no member named 'ratio'; did you m
ean 'int t::m_ratio'? (accessible via 'int t::get_ratio() const')
17 | return ptr->ratio;
| ^~~~~
| get_ratio()

In addition, various diagnostics in the C++ front-end have been
streamlined by consolidating the suggestion into the initial error,
rather than emitting a follow-up note:
$ g++ typo.cc
typo.cc:5:13: error: 'BUFSIZE' was not declared in this scope; did you mean 'BUF
_SIZE'?
5 | uint8_t buf[BUFSIZE];
| ^~~~~~~
| BUF_SIZE

[60]Runtime Library (libstdc++)

* Improved support for C++17, including:
+ The C++17 implementation is no longer experimental.
+ Parallel algorithms and <execution> (requires [61]Thread
Building Blocks 2018 or newer).
+ <memory_resource>.
+ Using the types and functions in <filesystem> does not require
linking with -lstdc++fs now.
* Improved experimental support for C++2a, including:
+ Type traits std::remove_cvref, std::unwrap_reference,
std::unwrap_decay_ref, std::is_nothrow_convertible, and
std::type_identity.
+ Headers <bit> and <version>.
+ Uniform container erasure (std::erase_if).
+ contains member of maps and sets.
+ String prefix and suffix checking (starts_with, ends_with).
+ Functions std::midpoint and std::lerp for interpolation.
+ std::bind_front.
+ std::visit<R>.
+ std::assume_aligned.
+ Uses-allocator construction utilities.
+ std::pmr::polymorphic_allocator<std::byte>.
+ Library support for char8_t type.
+ Destroying delete.
+ std::is_constant_evaluated() function.
* Support for opening file streams with wide character paths on
Windows
* Incomplete support for the C++17 Filesystem library and the
Filesystem TS on Windows.
* Incomplete, experimental support for the Networking TS.

[62]D

* Support for the D programming language has been added to GCC,
implementing version 2.076 of the language and run-time library.

[63]Fortran

* Asynchronous I/O is now fully supported. The program needs to be
linked against the pthreads library to use it, otherwise the I/O is
done synchronously. For systems which do not support POSIX
condition variables, such as AIX, all I/O is still done
synchronously.
* The BACK argument for MINLOC and MAXLOC has been implemented.
* The FINDLOC intrinsic function has been implemented.
* The IS_CONTIGUOUS intrinsic function has been implemented.
* Direct access to the real and imaginary parts of a complex variable
via c%re and c%im has been implemented.
* Type parameter inquiry via str%len and a%kind has been implemented.
* C descriptors and the ISO_Fortran_binding.h source file have been
implemented.
* The MAX and MIN intrinsics are no longer guaranteed to return any
particular value in case one of the arguments is a NaN. Note that
this conforms to the Fortran standard and to what other Fortran
compilers do. If there is a need to handle that case in some
specific way, one needs to explicitly check for NaN's before
calling MAX or MIN, e.g. by using the IEEE_IS_NAN function from the
intrinsic module IEEE_ARITHMETIC.
* A new command-line option [64]-fdec-include, set also by the
[65]-fdec option, has been added to increase compatibility with
legacy code. With this option, an INCLUDE directive is also parsed
as a statement, which allows the directive to be spread across
multiple source lines with line continuations.
* A new [66]BUILTIN directive, has been added. The purpose of the
directive is to provide an API between the GCC compiler and the GNU
C Library which would define vector implementations of math
routines.

[67]Go

* GCC 9 provides a complete implementation of the Go 1.12.2 user
packages.

[68]libgccjit

* The libgccjit API gained a new entry point:
[69]gcc_jit_context_add_driver_option.

[70]New Targets and Target Specific Improvements

[71]AArch64 & Arm

* Support has been added for the following processors (GCC
identifiers in parentheses):
+ Arm Cortex-A76 (cortex-a76).
+ Arm Cortex-A55/Cortex-A76 DynamIQ big.LITTLE
(cortex-a76.cortex-a55).
+ Arm Neoverse N1 (neoverse-n1).
The GCC identifiers can be used as arguments to the -mcpu or -mtune
options, for example: -mcpu=cortex-a76 or
-mtune=cortex-a76.cortex-a55 or as arguments to the equivalent
target attributes and pragmas.
* The Armv8.3-A complex number instructions are now supported via
intrinsics when the option -march=armv8.3-a or equivalent is
specified. For the half-precision floating-point variants of these
instructions use the architecture extension flag +fp16, e.g.
-march=armv8.3-a+fp16.
The intrinsics are defined by the ACLE specification.
* The Armv8.5-A architecture is now supported through the
-march=armv8.5-a option.
* The Armv8.5-A architecture also adds some security features that
are optional to all older architecture versions. These are now
supported and only affect the assembler.
+ Speculation Barrier instruction through the -march=armv8-a+sb
option.
+ Execution and Data Prediction Restriction instructions through
the -march=armv8-a+predres option.
+ Speculative Store Bypass Safe instruction through the
-march=armv8-a+ssbs option. This does not require a compiler
option for Arm and thus -march=armv8-a+ssbs is an
AArch64-specific option.

AArch64 specific

* Support has been added for the Arm Neoverse E1 processor
(-mcpu=neoverse-e1).
* The AArch64 port now has support for stack clash protection using
the [72]-fstack-clash-protection option. The probing interval/guard
size can be set by using --param
stack-clash-protection-guard-size=12|16. The value of this
parameter must be in bytes represented as a power of two. The two
supported values for this parameter are 12 (for a 4KiB size, 2^12)
and 16 (for a 64KiB size, 2^16). The default value is 16 (64Kb) and
can be changed at configure time using the flag
--with-stack-clash-protection-guard-size=12|16.
* The option -msign-return-address= has been deprecated. This has
been replaced by the new -mbranch-protection= option. This new
option can now be used to enable the return address signing as well
as the new Branch Target Identification feature of Armv8.5-A
architecture. For more information on the arguments accepted by
this option, please refer to [73]AArch64-Options.
* The following optional extensions to Armv8.5-A architecture are now
supported and only affect the assembler.
+ Random Number Generation instructions through the
-march=armv8.5-a+rng option.
+ Memory Tagging Extension through the -march=armv8.5-a+memtag
option.

Arm specific

* Support for the deprecated Armv2 and Armv3 architectures and their
variants has been removed. Their corresponding -march values and
the -mcpu options that used these architectures have been removed.
* Support for the Armv5 and Armv5E architectures (which have no known
implementations) has been removed. Note that Armv5T, Armv5TE and
Armv5TEJ architectures remain supported.
* Corrected FPU configurations for Cortex-R7 and Cortex-R8 when using
their respective -mcpu options.

[74]AMD GCN

* A new back end targeting AMD GCN GPUs has been contributed to GCC.
The implementation is currently limited to compiling
single-threaded, stand-alone programs. Future versions will add
support for offloading multi-threaded kernels via OpenMP and
OpenACC. The following devices are supported (GCC identifiers in
parentheses):
+ Fiji (fiji).
+ Vega 10 (gfx900).

[75]ARC

* LRA is now on by default for the ARC target. This can be controlled
by -mlra.
* Add support for frame code-density and branch-and-index
instructions.

[76]C-SKY

* A new back end targeting C-SKY V2 processors has been contributed
to GCC.

[77]IA-32/x86-64

* Support of Intel MPX (Memory Protection Extensions) has been
removed.
* New ISA extension support for Intel PTWRITE was added to GCC.
PTWRITE intrinsics are available via the -mptwrite compiler switch.
* GCC now supports the Intel CPU named Cascade Lake with AVX512
extensions through -march=cascadelake. The switch enables the
following ISA extensions: AVX512F, AVX512VL, AVX512CD, AVX512BW,
AVX512DQ, AVX512VNNI.

[78]MIPS

* The Loongson loongson-mmi and loongson-ext extensions have been
split from loongson3a:
+ loongson-mmi contains the Loongson MMI (MultiMedia extensions
Instructions).
+ loongson-ext contains the Loongson EXT (EXTensions
instructions).
* The Loongson EXT2 (EXTensions R2 instructions) are now supported.
+ loongson-ext2 contains the Loongson EXT2 instructions.
Command-line options-m[no-]loongson-mmi, -m[no-]loongson-ext, and
-m[no-]loongson-ext2 enable or disable those extensions.
* Support has been added for the following processors (GCC
identifiers in parentheses):
+ Loongson 3A1000 (gs464) which enables loongson-mmi,
loongson-ext by default.
+ Loongson 3A2000/3A3000 (gs464e) which enables loongson-mmi,
loongson-ext, loongson-ext2 by default.
+ Loongson 2K1000 (gs264e) which enables loongson-ext,
loongson-ext2, msa by default.
The GCC identifiers can be used as arguments to the -mcpu and
-mtune options (as in -mcpu=gs464 or -mtune=gs464e) or as arguments
to the equivalent target attributes and pragmas.

[79]OpenRISC

* A new back end targeting OpenRISC processors has been contributed
to GCC.

[80]S/390, System z, IBM z Systems

* Support for the arch13 architecture has been added. When using the
-march=arch13 option, the compiler will generate code making use of
the new instructions introduced with the vector enhancement
facility 2 and the miscellaneous instruction extension facility 2.
The -mtune=arch13 option enables arch13 specific instruction
scheduling without making use of new instructions.
* Builtins for the new vector instructions have been added and can be
enabled using the -mzvector option.
* Support for ESA architecture machines g5 and g6 is deprecated since
GCC 6.1.0 and has been removed now.
* When compiling with -march=z14 or higher GCC emits alignments hints
on the vector load/store instructions (8 or 16 byte).
* Functions now have a default alignment of 16 bytes. This helps with
branch prediction effects.
* -mfentry is now supported. As well as the mcount mechanism the
__fentry__ is called before the function prologue. However, since
just a single instruction is required to call __fentry__ the call
sequence imposes a smaller overhead than mcount (4 instructions).
The produced code is compatible only with newer glibc versions,
which provide the __fentry__ symbol and do not clobber r0 when
resolving lazily bound functions. -mfentry is only supported when
generating 64-bit code and does not work with nested C functions.
* The -mnop-mcount option can be used to emit NOP instructions
instead of an mcount or fentry call stub.
* With the -mrecord-mcount option a __mcount_loc section is generated
containing pointers to each profiling call stub. This is useful for
automatically patching in and out calls.

[81]Operating Systems

[82]Solaris

* g++ now unconditionally enables large file support when compiling
32-bit code.
* Support for the AddressSanitizer and UndefinedBehaviorSanitizer has
been merged from LLVM. For the moment, this only works for 32-bit
code on both SPARC and x86.
* An initial port of the D runtime library has been completed on
Solaris 11/x86. It requires the use of GNU as. Solaris 11/SPARC
support is still work-in-progress.

[83]Windows

* A C++ Microsoft ABI bitfield layout bug, [84]PR87137 has been
fixed. A non-field declaration could cause the current bitfield
allocation unit to be completed, incorrectly placing a following
bitfield into a new allocation unit. The Microsoft ABI is selected
for:
+ Mingw targets
+ PowerPC, IA-32 or x86-64 targets when the -mms-bitfields
option is specified, or __attribute__((ms_struct)) is used
+ SuperH targets when the -mhitachi option is specified, or
__attribute__((renesas)) is used

[85]Improvements for plugin authors

* GCC's diagnostic subsystem now has a way to logically group
together related diagnostics, auto_diagnostic_group. Such
diagnostics will be nested by the output of
[86]-fdiagnostics-format=json.
* GCC now has a set of [87]user experience guidelines for GCC, with
information and advice on implementing new diagnostics.

Other significant improvements

* GCC's internal "selftest" suite now runs for C++ as well as C (in
debug builds of the compiler).

[88]GCC 9.1

This is the [89]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 9.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[90]GCC 9.2

This is the [91]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 9.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[92]GCC 9.3

This is the [93]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 9.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[94]GCC 9.4

This is the [95]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 9.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Target Specific Changes

AArch64

* The option -moutline-atomics has been added to aid deployment of
the Large System Extensions (LSE) on GNU/Linux systems built with a
baseline architecture targeting Armv8-A. When the option is
specified code is emitted to detect the presence of LSE
instructions at run time and use them for standard atomic
operations. For more information please refer to the documentation.
* GCC now supports the Fujitsu A64FX. The associated -mcpu and -mtune
options are -mcpu=a64fx and -mtune=a64fx respectively. In
particular, -mcpu=a64fx generates code for Armv8.2-A with SVE and
tunes the code for the A64FX. This includes tuning the SVE code,
although by default the code is still length-agnostic and so works
for all SVE implementations. Adding -msve-vector-bits=512 makes the
code specific to 512-bit SVE.

[96]GCC 9.5

This is the [97]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 9.5 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

For questions related to the use of GCC, please consult these web
pages and the [98]GCC manuals. If that fails, the
[99][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [100][email protected]. All of [101]our lists have public
archives.

Copyright (C) [102]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [103]maintained by the GCC team. Last modified
2025-01-31.

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63. https://gcc.gnu.org/gcc-9/changes.html#fortran
64. https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gfortran/Fortran-Dialect-Options.html#index-fdec-include
65. https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gfortran/Fortran-Dialect-Options.html#index-fdec
66. https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gfortran/BUILTIN-directive.html#BUILTIN-directive
67. https://gcc.gnu.org/gcc-9/changes.html#go
68. https://gcc.gnu.org/gcc-9/changes.html#jit
69. https://gcc.gnu.org/onlinedocs/gcc-9.1.0/jit/topics/contexts.html#gcc_jit_context_add_driver_option
70. https://gcc.gnu.org/gcc-9/changes.html#targets
71. https://gcc.gnu.org/gcc-9/changes.html#arm-targets
72. https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gcc/Instrumentation-Options.html#index-fstack-protector
73. https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gcc/AArch64-Options.html#AArch64-Options
74. https://gcc.gnu.org/gcc-9/changes.html#amdgcn
75. https://gcc.gnu.org/gcc-9/changes.html#arc
76. https://gcc.gnu.org/gcc-9/changes.html#csky
77. https://gcc.gnu.org/gcc-9/changes.html#x86
78. https://gcc.gnu.org/gcc-9/changes.html#mips
79. https://gcc.gnu.org/gcc-9/changes.html#or1k
80. https://gcc.gnu.org/gcc-9/changes.html#s390
81. https://gcc.gnu.org/gcc-9/changes.html#os
82. https://gcc.gnu.org/gcc-9/changes.html#solaris
83. https://gcc.gnu.org/gcc-9/changes.html#windows
84. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87137
85. https://gcc.gnu.org/gcc-9/changes.html#plugins
86. https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gcc/Diagnostic-Message-Formatting-Options.html#index-fdiagnostics-format
87. https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gccint/User-Experience-Guidelines.html
88. https://gcc.gnu.org/gcc-9/changes.html#GCC9.1
89. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=9.0
90. https://gcc.gnu.org/gcc-9/changes.html#GCC9.2
91. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=9.2
92. https://gcc.gnu.org/gcc-9/changes.html#GCC9.3
93. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=9.3
94. https://gcc.gnu.org/gcc-9/changes.html#GCC9.4
95. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=9.4
96. https://gcc.gnu.org/gcc-9/changes.html#GCC9.5
97. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=9.5
98. https://gcc.gnu.org/onlinedocs/
99. mailto:[email protected]
100. mailto:[email protected]
101. https://gcc.gnu.org/lists.html
102. https://www.fsf.org/
103. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-8/index.html

GCC 8 Release Series

(This release series is no longer supported.)

May 14, 2021

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 8.5.

This release is a bug-fix release, containing fixes for regressions in
GCC 8.4 relative to previous releases of GCC.

Release History

GCC 8.5
May 14, 2021 ([2]changes, [3]documentation)

GCC 8.4
Mar 4, 2020 ([4]changes, [5]documentation)

GCC 8.3
Feb 22, 2019 ([6]changes, [7]documentation)

GCC 8.2
Jul 26, 2018 ([8]changes, [9]documentation)

GCC 8.1
May 2, 2018 ([10]changes, [11]documentation)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [12]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [13]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [14]GCC
project web site or contact the [15]GCC development mailing list.

To obtain GCC please use [16]our mirror sites or [17]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [18]GCC manuals. If that fails, the
[19][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [20][email protected]. All of [21]our lists have public
archives.

Copyright (C) [22]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [23]maintained by the GCC team. Last modified
2024-05-30.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-8/changes.html
3. https://gcc.gnu.org/onlinedocs/8.5.0/
4. https://gcc.gnu.org/gcc-8/changes.html
5. https://gcc.gnu.org/onlinedocs/8.4.0/
6. https://gcc.gnu.org/gcc-8/changes.html
7. https://gcc.gnu.org/onlinedocs/8.3.0/
8. https://gcc.gnu.org/gcc-8/changes.html
9. https://gcc.gnu.org/onlinedocs/8.2.0/
10. https://gcc.gnu.org/gcc-8/changes.html
11. https://gcc.gnu.org/onlinedocs/8.1.0/
12. https://gcc.gnu.org/gcc-8/buildstat.html
13. https://gcc.gnu.org/onlinedocs/gcc-8.1.0/gcc/Contributors.html
14. https://gcc.gnu.org/index.html
15. mailto:[email protected]
16. https://gcc.gnu.org/mirrors.html
17. https://gcc.gnu.org/git.html
18. https://gcc.gnu.org/onlinedocs/
19. mailto:[email protected]
20. mailto:[email protected]
21. https://gcc.gnu.org/lists.html
22. https://www.fsf.org/
23. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-8/changes.html

GCC 8 Release Series
Changes, New Features, and Fixes

This page is a "brief" summary of some of the huge number of
improvements in GCC 8. You may also want to check out our [1]Porting to
GCC 8 page and the [2]full GCC documentation.

Caveats

* The default mode for C is now -std=gnu17 instead of -std=gnu11.
* Support for the obsolete SDB/coff debug info format has been
removed. The option -gcoff no longer does anything.
* The Cilk+ extensions to the C and C++ languages have been removed.
* The MPX extensions to the C and C++ languages have been deprecated
and will be removed in a future release.
* The extension allowing arithmetic on std::atomic<void*> and types
like std::atomic<R(*)()> has been deprecated.
* The non-standard C++0x std::copy_exception function was removed.
std::make_exception_ptr should be used instead.
* Support for the powerpc*-*-*spe* target ports which have been
recently unmaintained and untested in GCC has been declared
obsolete in GCC 8 as [3]announced. Unless there is activity to
revive them, the next release of GCC will have their sources
permanently removed.

[4]General Improvements

* Inter-procedural optimization improvements:
+ Reworked run-time estimation metrics leading to more realistic
guesses driving inliner and cloning heuristics.
+ The ipa-pure-const pass is extended to propagate the malloc
attribute, and the corresponding warning option
-Wsuggest-attribute=malloc emits a diagnostic for functions
which can be annotated with the malloc attribute.
* Profile driven optimization improvements:
+ New infrastructure for representing profiles (both statically
guessed and profile feedback) which allows propagation of
additional information about the reliability of the profile.
+ A number of improvements in the profile updating code solving
problems found by new verification code.
+ Static detection of code which is not executed in a valid run
of the program. This includes paths which trigger undefined
behavior as well as calls to functions declared with the cold
attribute. Newly the noreturn attribute does not imply all
effects of cold to differentiate between exit (which is
noreturn) and abort (which is in addition not executed in
valid runs).
+ -freorder-blocks-and-partition, a pass splitting function
bodies into hot and cold regions, is now enabled by default at
-O2 and higher for x86 and x86-64.
* Link-time optimization improvements:
+ We have significantly improved debug information on ELF
targets using DWARF by properly preserving language-specific
information. This allows for example the libstdc++
pretty-printers to work with LTO optimized executables.
* A new option -fcf-protection=[full|branch|return|none] is
introduced to perform code instrumentation to increase program
security by checking that target addresses of control-flow transfer
instructions (such as indirect function call, function return,
indirect jump) are valid. Currently the instrumentation is
supported on x86 GNU/Linux targets only. See the user guide for
further information about the option syntax and section "New
Targets and Target Specific Improvements" for IA-32/x86-64 for more
details.
* The -gcolumn-info option is now enabled by default. It includes
column information in addition to just filenames and line numbers
in DWARF debugging information.
* The polyhedral-based loop nest optimization pass
-floop-nest-optimize has been overhauled. It's still considered
experimental and may not result in any runtime improvements.
* Two new classical loop nest optimization passes have been added.
-floop-unroll-and-jam performs outer loop unrolling and fusing of
the inner loop copies. -floop-interchange exchanges loops in a loop
nest to improve data locality. Both passes are enabled by default
at -O3 and above.
* The classic loop nest optimization pass -ftree-loop-distribution
has been improved and enabled by default at -O3 and above. It
supports loop nest distribution in some restricted scenarios; it
also supports cancellable innermost loop distribution with loop
versioning under run-time alias checks.
* The new option -fstack-clash-protection causes the compiler to
insert probes whenever stack space is allocated statically or
dynamically to reliably detect stack overflows and thus mitigate
the attack vector that relies on jumping over a stack guard page as
provided by the operating system.
* A new pragma GCC unroll has been implemented in the C family of
languages, as well as Fortran and Ada, so as to make it possible
for the user to have a finer-grained control over the loop
unrolling optimization.
* GCC has been enhanced to detect more instances of meaningless or
mutually exclusive attribute specifications and handle such
conflicts more consistently. Mutually exclusive attribute
specifications are ignored with a warning regardless of whether
they appear on the same declaration or on distinct declarations of
the same entity. For example, because the noreturn attribute on the
second declaration below is mutually exclusive with the malloc
attribute on the first, it is ignored and a warning is issued.
>
void* __attribute__ ((malloc)) f (unsigned);
void* __attribute__ ((noreturn)) f (unsigned);

warning: ignoring attribute 'noreturn' because it conflicts with attribute
'malloc' [-Wattributes]
* The gcov tool can distinguish functions that begin on a same line
in a source file. This can be a different template instantiation or
a class constructor:

File 'ins.C'
Lines executed:100.00% of 8
Creating 'ins.C.gcov'

-: 0:Source:ins.C
-: 0:Graph:ins.gcno
-: 0:Data:ins.gcda
-: 0:Runs:1
-: 0:Programs:1
-: 1:template<class T>
-: 2:class Foo
-: 3:{
-: 4: public:
2: 5: Foo(): b (1000) {}
------------------
Foo<char>::Foo():
1: 5: Foo(): b (1000) {}
------------------
Foo<int>::Foo():
1: 5: Foo(): b (1000) {}
------------------
2: 6: void inc () { b++; }
------------------
Foo<char>::inc():
1: 6: void inc () { b++; }
------------------
Foo<int>::inc():
1: 6: void inc () { b++; }
------------------
-: 7:
-: 8: private:
-: 9: int b;
-: 10:};
-: 11:
1: 12:int main(int argc, char **argv)
-: 13:{
1: 14: Foo<int> a;
1: 15: Foo<char> b;
-: 16:
1: 17: a.inc ();
1: 18: b.inc ();
1: 19:}

* The gcov tool has more accurate numbers for execution of lines in a
source file.
* The gcov tool can use TERM colors to provide more readable output.
* AddressSanitizer gained a new pair of sanitization options,
-fsanitize=pointer-compare and -fsanitize=pointer-subtract, which
warn about subtraction (or comparison) of pointers that point to a
different memory object:

int
main ()
{
/* Heap allocated memory. */
char *heap1 = (char *)__builtin_malloc (42);
char *heap2 = (char *)__builtin_malloc (42);
if (heap1 > heap2)
return 1;

return 0;
}

==17465==ERROR: AddressSanitizer: invalid-pointer-pair: 0x604000000010 0x6040000
00050
#0 0x40070f in main /tmp/pointer-compare.c:7
#1 0x7ffff6a72a86 in __libc_start_main (/lib64/libc.so.6+0x21a86)
#2 0x400629 in _start (/tmp/a.out+0x400629)

0x604000000010 is located 0 bytes inside of 42-byte region [0x604000000010,0x604
00000003a)
allocated by thread T0 here:
#0 0x7ffff6efb390 in __interceptor_malloc ../../../../libsanitizer/asan/asan
_malloc_linux.cc:86
#1 0x4006ea in main /tmp/pointer-compare.c:5
#2 0x7ffff6a72a86 in __libc_start_main (/lib64/libc.so.6+0x21a86)

0x604000000050 is located 0 bytes inside of 42-byte region [0x604000000050,0x604
00000007a)
allocated by thread T0 here:
#0 0x7ffff6efb390 in __interceptor_malloc ../../../../libsanitizer/asan/asan
_malloc_linux.cc:86
#1 0x4006f8 in main /tmp/pointer-compare.c:6
#2 0x7ffff6a72a86 in __libc_start_main (/lib64/libc.so.6+0x21a86)

SUMMARY: AddressSanitizer: invalid-pointer-pair /tmp/pointer-compare.c:7 in main

* The store merging pass has been enhanced to handle bit-fields and
not just constant stores, but also data copying from adjacent
memory locations into other adjacent memory locations, including
bitwise logical operations on the data. The pass can also handle
byte swapping into memory locations.
* The undefined behavior sanitizer gained two new options included in
-fsanitize=undefined: -fsanitize=builtin which diagnoses at run
time invalid arguments to __builtin_clz or __builtin_ctz prefixed
builtins, and -fsanitize=pointer-overflow which performs cheap run
time tests for pointer wrapping.
* A new attribute no_sanitize can be applied to functions to instruct
the compiler not to do sanitization of the options provided as
arguments to the attribute. Acceptable values for no_sanitize match
those acceptable by the -fsanitize command-line option.

void __attribute__ ((no_sanitize ("alignment", "object-size")))
f () { /* Do something. */; }

[5]New Languages and Language specific improvements

[6]Ada

* For its internal exception handling used on the host for error
recovery in the front-end, the compiler now relies on the native
exception handling mechanism of the host platform, which should be
more efficient than the former mechanism.

[7]BRIG (HSAIL)

In this release cycle, the focus for the BRIGFE was on stabilization
and performance improvements. Also a couple of completely new features
were added.
* Improved support for function and module scope group segment
variables. PRM specs define function and module scope group segment
variables as an experimental feature. However, PRM test suite uses
them. Now group segment is handled by separate book keeping of
module scope and function (kernel) offsets. Each function has a
"frame" in the group segment offset to which is given as an
argument, similar to traditional call stack frame handling.
* Reduce the number of type conversions due to the untyped HSAIL
registers. Instead of always representing the HSAIL's untyped
registers as unsigned int, the gccbrig now pre-analyzes the BRIG
code and builds the register variables as a type used the most when
storing or reading data to/from each register. This reduces the
number of total casts which cannot be always optimized away.
* Support for BRIG_KIND_NONE directives.
* Made -O3 the default optimization level for BRIGFE.
* Fixed illegal addresses generated from address expressions which
refer only to offset 0.
* Fixed a bug with reg+offset addressing on 32b segments. In 'large'
mode, the offset is treated as 32-bit unless it's in global,
read-only or kernarg address space.
* Fixed a crash caused sometimes by calls with more than 4 arguments.
* Fixed a mis-execution issue with kernels that have both unexpanded
ID functions and calls to subfunctions.
* Treat HSAIL barrier builtins as setjmp/longjump style functions to
avoid illegal optimizations.
* Ensure per WI copies of private variables are aligned correctly.
* libhsail-rt: Assume the host runtime allocates the work group
memory.

[8]C family

* New command-line options have been added for the C and C++
compilers:
+ [9]-Wmultistatement-macros warns about unsafe macros expanding
to multiple statements used as a body of a statement such as
if, else, while, switch, or for.
+ [10]-Wstringop-truncation warns for calls to bounded string
manipulation functions such as strncat, strncpy, and stpncpy
that might either truncate the copied string or leave the
destination unchanged. For example, the following call to
strncat is diagnosed because it appends just three of the four
characters from the source string.
void append (char *buf, size_t bufsize)
{
strncat (buf, ".txt", 3);
}
warning: 'strncat' output truncated copying 3 bytes from a string of length 4 [-
Wstringop-truncation]
Similarly, in the following example, the call to strncpy
specifies the size of the destination buffer as the bound. If
the length of the source string is equal to or greater than
this size the result of the copy will not be NUL-terminated.
Therefore, the call is also diagnosed. To avoid the warning,
specify sizeof buf - 1 as the bound and set the last element
of the buffer to NUL.
void copy (const char *s)
{
char buf[80];
strncpy (buf, s, sizeof buf);
...
}
warning: 'strncpy' specified bound 80 equals destination size [-Wstringop-trunca
tion]
The -Wstringop-truncation option is included in -Wall.
Note that due to GCC bug [11]82944, defining strncat, strncpy,
or stpncpy as a macro in a system header as some
implementations do, suppresses the warning.
+ [12]-Wif-not-aligned controls warnings issued in response to
invalid uses of objects declared with attribute
[13]warn_if_not_aligned.
The -Wif-not-aligned option is included in -Wall.
+ [14]-Wmissing-attributes warns when a declaration of a
function is missing one or more attributes that a related
function is declared with and whose absence may adversely
affect the correctness or efficiency of generated code. For
example, in C++, the warning is issued when an explicit
specialization of a primary template declared with attribute
alloc_align, alloc_size, assume_aligned, format, format_arg,
malloc, or nonnull is declared without it. Attributes
deprecated, error, and warning suppress the warning.
The -Wmissing-attributes option is included in -Wall.
+ [15]-Wpacked-not-aligned warns when a struct or union declared
with attribute packed defines a member with an explicitly
specified alignment greater than 1. Such a member will wind up
under-aligned. For example, a warning will be issued for the
definition of struct A in the following:
struct __attribute__ ((aligned (8)))
S8 { char a[8]; };

struct __attribute__ ((packed)) A
{
struct S8 s8;
};
warning: alignment 1 of 'struct S' is less than 8 [-Wpacked-not-aligned]
The -Wpacked-not-aligned option is included in -Wall.
+ -Wcast-function-type warns when a function pointer is cast to
an incompatible function pointer. This warning is enabled by
-Wextra.
+ -Wsizeof-pointer-div warns for suspicious divisions of the
size of a pointer by the size of the elements it points to,
which looks like the usual way to compute the array size but
won't work out correctly with pointers. This warning is
enabled by -Wall.
+ -Wcast-align=strict warns whenever a pointer is cast such that
the required alignment of the target is increased. For
example, warn if a char * is cast to an int * regardless of
the target machine.
+ -fprofile-abs-path creates absolute path names in the .gcno
files. This allows gcov to find the correct sources in
projects where compilations occur with different working
directories.
* -fno-strict-overflow is now mapped to -fwrapv -fwrapv-pointer and
signed integer overflow is now undefined by default at all
optimization levels. Using -fsanitize=signed-integer-overflow is
now the preferred way to audit code, -Wstrict-overflow is
deprecated.
* The [16]-Warray-bounds option has been improved to detect more
instances of out-of-bounds array indices and pointer offsets. For
example, negative or excessive indices into flexible array members
and string literals are detected.
* The [17]-Wrestrict option introduced in GCC 7 has been enhanced to
detect many more instances of overlapping accesses to objects via
restrict-qualified arguments to standard memory and string
manipulation functions such as memcpy and strcpy. For example, the
strcpy call in the function below attempts to truncate the string
by replacing its initial characters with the last four. However,
because the function writes the terminating NUL into a[4], the
copies overlap and the call is diagnosed.
void f (void)
{
char a[] = "abcd1234";
strcpy (a, a + 4);
...
}
warning: 'strcpy' accessing 5 bytes at offsets 0 and 4 overlaps 1 byte at offset
4 [-Wrestrict]
The -Wrestrict option is included in -Wall.
* Several optimizer enhancements have enabled improvements to the
[18]-Wformat-overflow and [19]-Wformat-truncation options. The
warnings detect more instances of buffer overflow and truncation
than in GCC 7 and are better at avoiding certain kinds of false
positives.
* When reporting mismatching argument types at a function call, the C
and C++ compilers now underline both the argument and the pertinent
parameter in the declaration.
$ gcc arg-type-mismatch.cc
arg-type-mismatch.cc: In function 'int caller(int, int, float)':
arg-type-mismatch.cc:5:24: error: invalid conversion from 'int' to 'const char*'
[-fpermissive]
return callee(first, second, third);
^~~~~~
arg-type-mismatch.cc:1:40: note: initializing argument 2 of 'int callee(int, c
onst char*, float)'
extern int callee(int one, const char *two, float three);
~~~~~~~~~~~~^~~

* When reporting on unrecognized identifiers, the C and C++ compilers
will now emit fix-it hints suggesting #include directives for
various headers in the C and C++ standard libraries.
$ gcc incomplete.c
incomplete.c: In function 'test':
incomplete.c:3:10: error: 'NULL' undeclared (first use in this function)
return NULL;
^~~~
incomplete.c:3:10: note: 'NULL' is defined in header '<stddef.h>'; did you forge
t to '#include <stddef.h>'?
incomplete.c:1:1:
+#include <stddef.h>
const char *test(void)
incomplete.c:3:10:
return NULL;
^~~~
incomplete.c:3:10: note: each undeclared identifier is reported only once for ea
ch function it appears in

$ gcc incomplete.cc
incomplete.cc:1:6: error: 'string' in namespace 'std' does not name a type
std::string s("hello world");
^~~~~~
incomplete.cc:1:1: note: 'std::string' is defined in header '<string>'; did you
forget to '#include <string>'?
+#include <string>
std::string s("hello world");
^~~

* The C and C++ compilers now use more intuitive locations when
reporting on missing semicolons, and offer fix-it hints:
$ gcc t.c
t.c: In function 'test':
t.c:3:12: error: expected ';' before '}' token
return 42
^
;
}
~

* When reporting on missing '}' and ')' tokens, the C and C++
compilers will now highlight the corresponding '{' and '(' token,
issuing a 'note' if it's on a separate line:
$ gcc unclosed.c
unclosed.c: In function 'log_when_out_of_range':
unclosed.c:12:50: error: expected ')' before '{' token
&& (temperature < MIN || temperature > MAX) {
^~
)
unclosed.c:11:6: note: to match this '('
if (logging_enabled && check_range ()
^

or highlighting it directly if it's on the same line:
$ gcc unclosed-2.c
unclosed-2.c: In function 'test':
unclosed-2.c:8:45: error: expected ')' before '{' token
if (temperature < MIN || temperature > MAX {
~ ^~
)

They will also emit fix-it hints.

[20]C

* New options -std=c17, to select support for the 2018 edition of the
ISO C standard (__STDC_VERSION__ == 201710L), and -std=gnu17, for
C17 with GNU extensions.
* The default mode has been changed to -std=gnu17.

[21]C++

* GCC 8 (-fabi-version=12) has a couple of corrections to the calling
convention, which changes the ABI for some uncommon code:
+ Passing an empty class as an argument now takes up no space on
x86_64, as required by the psABI.
+ Passing or returning a class with only deleted copy and move
constructors now uses the same calling convention as a class
with a non-trivial copy or move constructor. This only affects
C++17 mode, as in earlier standards passing or returning such
a class was impossible.
+ WARNING: In GCC 8.1 the second change mistakenly also affects
classes with a deleted copy constructor and defaulted trivial
move constructor (bug [22]c++/86094). This issue is fixed in
GCC 8.2 (-fabi-version=13).
You can test whether these changes affect your code with -Wabi=11
(or -Wabi=12 in GCC 8.2 for the third issue); if these changes are
problematic for your project, the GCC 7 ABI can be selected with
-fabi-version=11.
* The value of the C++11 alignof operator has been corrected to match
C _Alignof (minimum alignment) rather than GNU __alignof__
(preferred alignment); on ia32 targets this means that
alignof(double) is now 4 rather than 8. Code that wants the
preferred alignment should use __alignof__ instead.
* New command-line options have been added for the C++ compiler to
control warnings:
+ [23]-Wclass-memaccess warns when objects of non-trivial class
types are manipulated in potentially unsafe ways by raw memory
functions such as memcpy, or realloc. The warning helps detect
calls that bypass user-defined constructors or copy-assignment
operators, corrupt virtual table pointers, data members of
const-qualified types or references, or member pointers. The
warning also detects calls that would bypass access controls
to data members. For example, a call such as:
memcpy (&std::cout, &std::cerr, sizeof std::cout);
results in
warning: 'void* memcpy(void*, const void*, long unsigned int)' writing t
o an object of type 'std::ostream' {aka 'class std::basic_ostream<char>'} with n
o trivial copy-assignment [-Wclass-memaccess]
The -Wclass-memaccess option is included in -Wall.
* The C++ front end has experimental support for some of the upcoming
C++2a draft features with the -std=c++2a or -std=gnu++2a flags,
including designated initializers, default member initializers for
bit-fields, __VA_OPT__ (except that #__VA_OPT__ is unsupported),
lambda [=, this] captures, etc. For a full list of new features,
see [24]the C++ status page.
* When reporting on attempts to access private fields of a class or
struct, the C++ compiler will now offer fix-it hints showing how to
use an accessor function to get at the field in question, if one
exists.
$ gcc accessor.cc
accessor.cc: In function 'void test(foo*)':
accessor.cc:12:12: error: 'double foo::m_ratio' is private within this context
if (ptr->m_ratio >= 0.5)
^~~~~~~
accessor.cc:7:10: note: declared private here
double m_ratio;
^~~~~~~
accessor.cc:12:12: note: field 'double foo::m_ratio' can be accessed via 'double
foo::get_ratio() const'
if (ptr->m_ratio >= 0.5)
^~~~~~~
get_ratio()

* The C++ compiler can now give you a hint if you use a macro before
it was defined (e.g. if you mess up the order of your #include
directives):
$ gcc ordering.cc
ordering.cc:2:24: error: expected ';' at end of member declaration
virtual void clone() const OVERRIDE { }
^~~~~
;
ordering.cc:2:30: error: 'OVERRIDE' does not name a type
virtual void clone() const OVERRIDE { }
^~~~~~~~
ordering.cc:2:30: note: the macro 'OVERRIDE' had not yet been defined
In file included from ordering.cc:5:
c++11-compat.h:2: note: it was later defined here
#define OVERRIDE override

* The -Wold-style-cast diagnostic can now emit fix-it hints telling
you when you can use a static_cast, const_cast, or
reinterpret_cast.
$ gcc -c old-style-cast-fixits.cc -Wold-style-cast
old-style-cast-fixits.cc: In function 'void test(void*)':
old-style-cast-fixits.cc:5:19: warning: use of old-style cast to 'struct foo*' [
-Wold-style-cast]
foo *f = (foo *)ptr;
^~~
----------
static_cast<foo *> (ptr)

* When reporting on problems within extern "C" linkage
specifications, the C++ compiler will now display the location of
the start of the extern "C".
$ gcc -c extern-c.cc
extern-c.cc:3:1: error: template with C linkage
template <typename T> void test (void);
^~~~~~~~
In file included from extern-c.cc:1:
unclosed.h:1:1: note: 'extern "C"' linkage started here
extern "C" {
^~~~~~~~~~
extern-c.cc:3:39: error: expected '}' at end of input
template <typename T> void test (void);
^
In file included from extern-c.cc:1:
unclosed.h:1:12: note: to match this '{'
extern "C" {
^

* When reporting on mismatching template types, the C++ compiler will
now use color to highlight the mismatching parts of the template,
and will elide the parameters that are common between two
mismatching templates, printing [...] instead:
$ gcc templates.cc
templates.cc: In function 'void test()':
templates.cc:9:8: error: could not convert 'vector<double>()' from 'vector<doubl
e>' to 'vector<int>'
fn_1(vector<double> ());
^~~~~~~~~~~~~~~~~
templates.cc:10:8: error: could not convert 'map<int, double>()' from 'map<[...]
,double>' to 'map<[...],int>'
fn_2(map<int, double>());
^~~~~~~~~~~~~~~~~~

Those [...] elided parameters can be seen using -fno-elide-type:
$ gcc templates.cc -fno-elide-type
templates.cc: In function 'void test()':
templates.cc:9:8: error: could not convert 'vector<double>()' from 'vector<doubl
e>' to 'vector<int>'
fn_1(vector<double> ());
^~~~~~~~~~~~~~~~~
templates.cc:10:8: error: could not convert 'map<int, double>()' from 'map<int,d
ouble>' to 'map<int,int>'
fn_2(map<int, double>());
^~~~~~~~~~~~~~~~~~

The C++ compiler has also gained an option
-fdiagnostics-show-template-tree which visualizes such mismatching
templates in a hierarchical form:
$ gcc templates-2.cc -fdiagnostics-show-template-tree
templates-2.cc: In function 'void test()':
templates-2.cc:9:8: error: could not convert 'vector<double>()' from 'vector<dou
ble>' to 'vector<int>'
vector<
[double != int]>
fn_1(vector<double> ());
^~~~~~~~~~~~~~~~~
templates-2.cc:10:8: error: could not convert 'map<map<int, vector<double> >, ve
ctor<double> >()' from 'map<map<[...],vector<double>>,vector<double>>' to 'map<m
ap<[...],vector<float>>,vector<float>>'
map<
map<
[...],
vector<
[double != float]>>,
vector<
[double != float]>>
fn_2(map<map<int, vector<double>>, vector<double>> ());
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

which again works with -fno-elide-type:
$ gcc templates-2.cc -fdiagnostics-show-template-tree -fno-elide-type
templates-2.cc: In function 'void test()':
templates-2.cc:9:8: error: could not convert 'vector<double>()' from 'vector<dou
ble>' to 'vector<int>'
vector<
[double != int]>
fn_1(vector<double> ());
^~~~~~~~~~~~~~~~~
templates-2.cc:10:8: error: could not convert 'map<map<int, vector<double> >, ve
ctor<double> >()' from 'map<map<int,vector<double>>,vector<double>>' to 'map<map
<int,vector<float>>,vector<float>>'
map<
map<
int,
vector<
[double != float]>>,
vector<
[double != float]>>
fn_2(map<map<int, vector<double>>, vector<double>> ());
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* Flowing off the end of a non-void function is considered
unreachable and may be subject to optimization on that basis. As a
result of this change, -Wreturn-type warnings are enabled by
default for C++.

[25]Runtime Library (libstdc++)

* Improved experimental support for C++17, including the following
features:
+ Deduction guides to support class template argument deduction.
+ std::filesystem implementation.
+ std::char_traits<char> and std::char_traits<wchar_t> are
usable in constant expressions.
+ std::to_chars and std::from_chars (for integers only, not for
floating point types).
* Experimental support for C++2a: std::to_address (thanks to Glen
Fernandes) and std::endian.
* On GNU/Linux, std::random_device::entropy() accesses the kernel's
entropy count for the random device, if known (thanks to Xi
Ruoyao).
* Support for std::experimental::source_location.
* AddressSanitizer integration for std::vector, detecting
out-of-range accesses to the unused capacity of a vector.
* Extensions __gnu_cxx::airy_ai and __gnu_cxx::airy_bi added to the
Mathematical Special Functions.

[26]Fortran

* The main version of libfortran has been changed to 5.
* Parameterized derived types, a major feature of Fortran 2003, have
been implemented.
* Partial support is provided for Fortran 2018 teams, which are
hierarchical subsets of images that execute independently of other
image subsets.
* The maximum rank for arrays has been increased to 15, conforming to
the Fortran 2008 standard.
* Transformational intrinsics are now fully supported in
initialization expressions.
* New flag -fc-prototypes to write C prototypes for BIND(C)
procedures and variables.
* If -fmax-stack-var-size is honored if given together with -Ofast,
-fstack-arrays is no longer set in that case.
* New options -fdefault-real-16 and -fdefault-real-10 to control the
default kind of REAL variables.
* A warning is now issued if an array subscript inside a DO loop
could lead to an out-of-bounds-access. The new option
-Wdo-subscript, enabled by -Wextra, warns about this even if the
compiler can not prove that the code will be executed.
* The Fortran front end now attempts to interchange loops if it is
deemed profitable. So far, this is restricted to FORALL and DO
CONCURRENT statements with multiple indices. This behavior be
controlled with the new flag -ffrontend-loop-interchange, which is
enabled with optimization by default. The
-Wfrontend-loop-interchange option warns about such occurrences.
* When an actual argument contains too few elements for a dummy
argument, an error is now issued. The -std=legacy option can be
used to still compile such code.
* The RECL= argument to OPEN and INQUIRE statements now allows 64-bit
integers, making records larger than 2GiB possible.
* The GFORTRAN_DEFAULT_RECL environment variable no longer has any
effect. The record length for preconnected units is now larger than
any practical limit, same as for sequential access units opened
without an explicit RECL= specifier.
* Character variables longer than HUGE(0) elements are now possible
on 64-bit targets. Note that this changes the procedure call ABI
for all procedures with character arguments on 64-bit targets, as
the type of the hidden character length argument has changed. The
hidden character length argument is now of type INTEGER(C_SIZE_T).
* Partial support is provided for Fortran 2018 teams, which are
hierarchical subsets of images that execute independently of other
image subsets.

[27]Go

* GCC 8 provides a complete implementation of the Go 1.10.1 user
packages.
* The garbage collector is now fully concurrent. As before, values
stored on the stack are scanned conservatively, but value stored in
the heap are scanned precisely.
* Escape analysis is fully implemented and enabled by default in the
Go front end. This significantly reduces the number of heap
allocations by allocating values on the stack instead.

[28]libgccjit

The libgccjit API gained four new entry points:
* [29]gcc_jit_type_get_vector and
* [30]gcc_jit_context_new_rvalue_from_vector for working with
vectors,
* [31]gcc_jit_type_get_aligned
* [32]gcc_jit_function_get_address

The C code generated by [33]gcc_jit_context_dump_reproducer_to_file is
now easier-to-read.

[34]New Targets and Target Specific Improvements

[35]AArch64

* The Armv8.4-A architecture is now supported. It can be used by
specifying the -march=armv8.4-a option.
* The Dot Product instructions are now supported as an optional
extension to the Armv8.2-A architecture and newer and are mandatory
on Armv8.4-A. The extension can be used by specifying the +dotprod
architecture extension. E.g. -march=armv8.2-a+dotprod.
* The Armv8-A +crypto extension has now been split into two
extensions for finer grained control:
+ +aes which contains the Armv8-A AES crytographic instructions.
+ +sha2 which contains the Armv8-A SHA2 and SHA1 cryptographic
instructions.
Using +crypto will now enable these two extensions.
* New Armv8.4-A FP16 Floating Point Multiplication Variant
instructions have been added. These instructions are mandatory in
Armv8.4-A but available as an optional extension to Armv8.2-A and
Armv8.3-A. The new extension can be used by specifying the +fp16fml
architectural extension on Armv8.2-A and Armv8.3-A. On Armv8.4-A
the instructions can be enabled by specifying +fp16.
* New cryptographic instructions have been added as optional
extensions to Armv8.2-A and newer. These instructions can be
enabled with:
+ +sha3 New SHA3 and SHA2 instructions from Armv8.4-A. This
implies +sha2.
+ +sm4 New SM3 and SM4 instructions from Armv8.4-A.
* The Scalable Vector Extension (SVE) is now supported as an optional
extension to the Armv8.2-A architecture and newer. This support
includes automatic vectorization with SVE instructions, but it does
not yet include the SVE Arm C Language Extensions (ACLE). It can be
enabled by specifying the +sve architecture extension (for example,
-march=armv8.2-a+sve). By default, the generated code works with
all vector lengths, but it can be made specific to N-bit vectors
using -msve-vector-bits=N.
* Support has been added for the following processors (GCC
identifiers in parentheses):
+ Arm Cortex-A75 (cortex-a75).
+ Arm Cortex-A55 (cortex-a55).
+ Arm Cortex-A55/Cortex-A75 DynamIQ big.LITTLE
(cortex-a75.cortex-a55).
The GCC identifiers can be used as arguments to the -mcpu or -mtune
options, for example: -mcpu=cortex-a75 or -mtune=cortex-a75 or as
arguments to the equivalent target attributes and pragmas.

[36]ARC

* Added support for:
+ Fast interrupts.
+ Naked functions.
+ aux variable attributes.
+ uncached type qualifier.
+ Secure functions via sjli instruction.
* New exception handling implementation.
* Revamped trampoline implementation.
* Refactored small data feature implementation, controlled via the -G
command-line option.
* New support for reduced register set ARC architecture
configurations, controlled via the -mrf16 command-line option.
* Refurbished and improved support for zero overhead loops.
Introduced -mlpc-width command-line option to control the width of
the lp_count register.

[37]ARM

* The -mfpu option now takes a new option setting of -mfpu=auto. When
set to this the floating-point and SIMD settings are derived from
the settings of the -mcpu or -march options. The internal CPU
configurations have been updated with information about the
permitted floating-point configurations supported. See the user
guide for further information about the extended option syntax for
controlling architectural extensions via the -march option.
-mfpu=auto is now the default setting unless the compiler has been
configured with an explicit --with-fpu option.
* The -march and -mcpu options now accept optional extensions to the
architecture or CPU option, allowing the user to enable or disable
any such extensions supported by that architecture or CPU such as
(but not limited to) floating-point and AdvancedSIMD. For example:
the option -mcpu=cortex-a53+nofp will generate code for the
Cortex-A53 processor with no floating-point support. This, in
combination with the new -mfpu=auto option, provides a
straightforward way of specifying a valid build target through a
single -mcpu or -march option. The -mtune option accepts the same
arguments as -mcpu but only the CPU name has an effect on tuning.
The architecture extensions do not have any effect. For details of
what extensions a particular architecture or CPU option supports
please refer to the [38]documentation.
* The -mstructure-size-boundary option has been deprecated and will
be removed in a future release.
* The default link behavior for Armv6 and Armv7-R targets has been
changed to produce BE8 format when generating big-endian images. A
new flag -mbe32 can be used to force the linker to produce legacy
BE32 format images. There is no change of behavior for Armv6-M and
other Armv7 or later targets: these already defaulted to BE8
format. This change brings GCC into alignment with other compilers
for the ARM architecture.
* The Armv8-R architecture is now supported. It can be used by
specifying the -march=armv8-r option.
* The Armv8.3-A architecture is now supported. It can be used by
specifying the -march=armv8.3-a option.
* The Armv8.4-A architecture is now supported. It can be used by
specifying the -march=armv8.4-a option.
* The Dot Product instructions are now supported as an optional
extension to the Armv8.2-A architecture and newer and are mandatory
on Armv8.4-A. The extension can be used by specifying the +dotprod
architecture extension. E.g. -march=armv8.2-a+dotprod.
* Support for setting extensions and architectures using the GCC
target pragma and attribute has been added. It can be used by
specifying #pragma GCC target ("arch=..."), #pragma GCC target
("+extension"), __attribute__((target("arch=..."))) or
__attribute__((target("+extension"))).
* New Armv8.4-A FP16 Floating Point Multiplication Variant
instructions have been added. These instructions are mandatory in
Armv8.4-A but available as an optional extension to Armv8.2-A and
Armv8.3-A. The new extension can be used by specifying the +fp16fml
architectural extension on Armv8.2-A and Armv8.3-A. On Armv8.4-A
the instructions can be enabled by specifying +fp16.
* Support has been added for the following processors (GCC
identifiers in parentheses):
+ Arm Cortex-A75 (cortex-a75).
+ Arm Cortex-A55 (cortex-a55).
+ Arm Cortex-A55/Cortex-A75 DynamIQ big.LITTLE
(cortex-a75.cortex-a55).
+ Arm Cortex-R52 for Armv8-R (cortex-r52).
The GCC identifiers can be used as arguments to the -mcpu or -mtune
options, for example: -mcpu=cortex-a75 or -mtune=cortex-r52 or as
arguments to the equivalent target attributes and pragmas.

[39]AVR

* The AVR port now supports the following XMEGA-like devices:

ATtiny212, ATtiny214, ATtiny412, ATtiny414, ATtiny416, ATtiny417,
ATtiny814, ATtiny816, ATtiny817, ATtiny1614, ATtiny1616, ATtiny1617,
ATtiny3214, ATtiny3216, ATtiny3217
The new devices are listed under [40]-mmcu=avrxmega3.
+ These devices see flash memory in the RAM address space, so
that features like PROGMEM and __flash are not needed any more
(as opposed to other AVR families for which read-only data
will be located in RAM except special, non-standard features
are used to locate and access such data). This requires that
the compiler is used with Binutils 2.29 or newer so that
[41]read-only data will be located in flash memory.
+ A new command-line option -mshort-calls is supported. This
option is used internally for multilib selection of the
avrxmega3 variants. It is not an optimization option. Do not
set it by hand.
* The compiler now generates [42]efficient interrupt service routine
(ISR) prologues and epilogues. This is achieved by using the new
[43]AVR pseudo instruction __gcc_isr which is supported and
resolved by the GNU assembler.
+ As the __gcc_isr pseudo-instruction will be resolved by the
assembler, inline assembly is transparent to the process. This
means that when inline assembly uses an instruction like INC
that clobbers the condition code, then the assembler will
detect this and generate an appropriate ISR prologue /
epilogue chunk to save / restore SREG as needed.
+ A new command-line option -mno-gas-isr-prologues disables the
generation of the __gcc_isr pseudo instruction. Any non-naked
ISR will save and restore SREG, tmp_reg and zero_reg, no
matter whether the respective register is clobbered or used.
+ The feature is turned on per default for all optimization
levels except for -O0 and -Og. It is explicitly enabled by
means of option -mgas-isr-prologues.
+ Support has been added for a new [44]AVR function attribute
no_gccisr. It can be used to disable __gcc_isr pseudo
instruction generation for individual ISRs.
+ This optimization is only available if GCC is configured with
GNU Binutils 2.29 or newer; or at least with a version of
Binutils that implements feature [45]PR21683.
* The compiler no more saves / restores registers in main; the effect
is the same as if attribute OS_task was specified for main. This
optimization can be switched off by the new command-line option
-mno-main-is-OS_task.

[46]IA-32/x86-64

* The x86 port now supports the naked function attribute.
* Better tuning for znver1 and Intel Core based CPUs.
* Vectorization cost metrics has been reworked leading to significant
improvements on some benchmarks.
* GCC now supports the Intel CPU named Cannonlake through
-march=cannonlake. The switch enables the AVX512VBMI, AVX512IFMA
and SHA ISA extensions.
* GCC now supports the Intel CPU named Icelake through
-march=icelake. The switch enables the AVX512VNNI, GFNI, VAES,
AVX512VBMI2, VPCLMULQDQ, AVX512BITALG, RDPID and AVX512VPOPCNTDQ
ISA extensions.
* GCC now supports the Intel Control-flow Enforcement Technology
(CET) extension through -fcf-protection option.

[47]NDS32

* New command-line options -mext-perf, -mext-perf2, and -mext-string
have been added for performance extension instructions.

[48]Nios II

* The Nios II back end has been improved to generate better-optimized
code. Changes include switching to LRA, more accurate cost models,
and more compact code for addressing static variables.
* New command-line options -mgprel-sec= and -mr0rel-sec= have been
added.
* The stack-smashing protection options are now enabled on Nios II.

[49]PA-RISC

* The default call ABI on 32-bit linux has been changed from callee
copies to caller copies. This affects objects larger than eight
bytes passed by value. The goal is to improve compatibility with
x86 and resolve issues with OpenMP.
* Other PA-RISC targets are unchanged.

[50]PowerPC / PowerPC64 / RS6000

* The PowerPC SPE support is split off to a separate powerpcspe port.
The separate port is deprecated and might be removed in a future
release.
* The Paired Single support (as used on some PPC750 CPUs, -mpaired,
powerpc*-*-linux*paired*) is deprecated and will be removed in a
future release.
* The Xilinx floating point support (-mxilinx-fpu,
powerpc-xilinx-eabi*) is deprecated and will be removed in a future
release.
* Support for using big-endian AltiVec intrinsics on a little-endian
target (-maltivec=be) is deprecated and will be removed in a future
release.

[51]Tile

* The TILE-Gx port is deprecated and will be removed in a future
release.

[52]Operating Systems

[53]Windows

* GCC on Microsoft Windows can now be configured via
--enable-mingw-wildcard or --disable-mingw-wildcard to force a
specific behavior for GCC itself with regards to supporting the
wildcard character. Prior versions of GCC would follow the
configuration of the MinGW runtime. This behavior can still be
obtained by not using the above options or by using
--enable-mingw-wildcard=platform.

[54]Improvements for plugin authors

* Plugins can now register a callback hook for when comments are
encountered by the C and C++ compilers, e.g. allowing for plugins
to handle documentation markup in code comments.
* The gdbinit support script for debugging GCC now has a
break-on-diagnostic command, providing an easy way to trigger a
breakpoint whenever a diagnostic is emitted.
* The API for creating fix-it hints now supports newlines, and for
emitting mutually incompatible fix-it hints for one diagnostic.

[55]GCC 8.1

This is the [56]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 8.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[57]GCC 8.2

This is the [58]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 8.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

General Improvements

* Fixed LTO link-time performance problems caused by an overflow in
the partitioning algorithm while building large binaries.

Language Specific Changes

C++

GCC 8.2 fixed a bug introduced in GCC 8.1 affecting passing or
returning of classes with a deleted copy constructor and defaulted
trivial move constructor (bug [59]c++/86094). GCC 8.2 introduces
-fabi-version=13 and makes it the default, ABI incompatibilities
between GCC 8.1 and 8.2 can be reported with -Wabi=12. See [60]C++
changes for more details.

Target Specific Changes

IA-32/x86-64

* -mtune=native performance regression [61]PR84413 on Intel Skylake
processors has been fixed.

[62]GCC 8.3

This is the [63]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 8.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Windows

* A C++ Microsoft ABI bitfield layout bug, [64]PR87137 has been
fixed. A non-field declaration could cause the current bitfield
allocation unit to be completed, incorrectly placing a following
bitfield into a new allocation unit. The Microsoft ABI is selected
for:
+ Mingw targets
+ PowerPC, IA-32 or x86-64 targets when the -mms-bitfields
option is specified, or __attribute__((ms_struct)) is used
+ SuperH targets when the -mhitachi option is specified, or
__attribute__((renesas)) is used
GCC 8 introduced additional cases of this defect, but rather than
resolve only those regressions, we decided to resolve all the cases
of this defect in single change.

[65]GCC 8.4

This is the [66]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 8.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[67]GCC 8.5

This is the [68]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 8.5 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Target Specific Changes

AArch64

* The option -moutline-atomics has been added to aid deployment of
the Large System Extensions (LSE) on GNU/Linux systems built with a
baseline architecture targeting Armv8-A. When the option is
specified code is emitted to detect the presence of LSE
instructions at run time and use them for standard atomic
operations. For more information please refer to the documentation.

For questions related to the use of GCC, please consult these web
pages and the [69]GCC manuals. If that fails, the
[70][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [71][email protected]. All of [72]our lists have public
archives.

Copyright (C) [73]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [74]maintained by the GCC team. Last modified
2025-01-31.

References

1. https://gcc.gnu.org/gcc-8/porting_to.html
2. https://gcc.gnu.org/onlinedocs/index.html#current
3. https://gcc.gnu.org/ml/gcc/2018-04/msg00102.html
4. https://gcc.gnu.org/gcc-8/changes.html#general
5. https://gcc.gnu.org/gcc-8/changes.html#languages
6. https://gcc.gnu.org/gcc-8/changes.html#ada
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17. https://gcc.gnu.org/onlinedocs/gcc-8.1.0/gcc/Warning-Options.html#index-Wrestrict
18. https://gcc.gnu.org/onlinedocs/gcc-8.1.0/gcc/Warning-Options.html#index-Wformat-overflow
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20. https://gcc.gnu.org/gcc-8/changes.html#c
21. https://gcc.gnu.org/gcc-8/changes.html#cxx
22. https://gcc.gnu.org/PR86094
23. https://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Dialect-Options.html#index-Wclass-memaccess
24. https://gcc.gnu.org/projects/cxx-status.html#cxx2a
25. https://gcc.gnu.org/gcc-8/changes.html#libstdcxx
26. https://gcc.gnu.org/gcc-8/changes.html#fortran
27. https://gcc.gnu.org/gcc-8/changes.html#go
28. https://gcc.gnu.org/gcc-8/changes.html#jit
29. https://gcc.gnu.org/onlinedocs/gcc-8.1.0/jit/topics/types.html#gcc_jit_type_get_vector
30. https://gcc.gnu.org/onlinedocs/gcc-8.1.0/jit/topics/expressions.html#gcc_jit_context_new_rvalue_from_vector
31. https://gcc.gnu.org/onlinedocs/gcc-8.1.0/jit/topics/types.html#gcc_jit_type_get_aligned
32. https://gcc.gnu.org/onlinedocs/gcc-8.1.0/jit/topics/function-pointers.html#gcc_jit_function_get_address
33. https://gcc.gnu.org/onlinedocs/gcc-8.1.0/jit/topics/contexts.html#gcc_jit_context_dump_reproducer_to_file
34. https://gcc.gnu.org/gcc-8/changes.html#targets
35. https://gcc.gnu.org/gcc-8/changes.html#aarch64
36. https://gcc.gnu.org/gcc-8/changes.html#arc
37. https://gcc.gnu.org/gcc-8/changes.html#arm
38. https://gcc.gnu.org/onlinedocs/gcc-8.1.0/gcc/ARM-Options.html#ARM-Options
39. https://gcc.gnu.org/gcc-8/changes.html#avr
40. https://gcc.gnu.org/onlinedocs/gcc-8.1.0/gcc/AVR-Options.html
41. https://sourceware.org/PR21472
42. https://gcc.gnu.org/PR20296
43. https://sourceware.org/binutils/docs-2.29/as/AVR-Pseudo-Instructions.html
44. https://gcc.gnu.org/onlinedocs/gcc-8.1.0/gcc/AVR-Function-Attributes.html
45. https://sourceware.org/PR21683
46. https://gcc.gnu.org/gcc-8/changes.html#x86
47. https://gcc.gnu.org/gcc-8/changes.html#nds32
48. https://gcc.gnu.org/gcc-8/changes.html#nios2
49. https://gcc.gnu.org/gcc-8/changes.html#hppa
50. https://gcc.gnu.org/gcc-8/changes.html#powerpc
51. https://gcc.gnu.org/gcc-8/changes.html#Tile
52. https://gcc.gnu.org/gcc-8/changes.html#os
53. https://gcc.gnu.org/gcc-8/changes.html#windows
54. https://gcc.gnu.org/gcc-8/changes.html#plugins
55. https://gcc.gnu.org/gcc-8/changes.html#GCC8.1
56. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=8.0
57. https://gcc.gnu.org/gcc-8/changes.html#GCC8.2
58. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=8.2
59. https://gcc.gnu.org/PR86094
60. https://gcc.gnu.org/gcc-8/changes.html#cxx
61. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84413
62. https://gcc.gnu.org/gcc-8/changes.html#GCC8.3
63. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=8.3
64. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87137
65. https://gcc.gnu.org/gcc-8/changes.html#GCC8.4
66. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=8.4
67. https://gcc.gnu.org/gcc-8/changes.html#GCC8.5
68. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=8.5
69. https://gcc.gnu.org/onlinedocs/
70. mailto:[email protected]
71. mailto:[email protected]
72. https://gcc.gnu.org/lists.html
73. https://www.fsf.org/
74. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-7/index.html

GCC 7 Release Series

(This release series is no longer supported.)

Nov 14, 2019

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 7.5.

This release is a bug-fix release, containing fixes for regressions in
GCC 7.4 relative to previous releases of GCC.

Release History

GCC 7.5
Nov 14, 2019 ([2]changes, [3]documentation)

GCC 7.4
Dec 6, 2018 ([4]changes, [5]documentation)

GCC 7.3
Jan 25, 2018 ([6]changes, [7]documentation)

GCC 7.2
Aug 14, 2017 ([8]changes, [9]documentation)

GCC 7.1
May 2, 2017 ([10]changes, [11]documentation)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [12]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [13]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [14]GCC
project web site or contact the [15]GCC development mailing list.

To obtain GCC please use [16]our mirror sites or [17]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [18]GCC manuals. If that fails, the
[19][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [20][email protected]. All of [21]our lists have public
archives.

Copyright (C) [22]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [23]maintained by the GCC team. Last modified
2024-05-30.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-7/changes.html
3. https://gcc.gnu.org/onlinedocs/7.5.0/
4. https://gcc.gnu.org/gcc-7/changes.html
5. https://gcc.gnu.org/onlinedocs/7.4.0/
6. https://gcc.gnu.org/gcc-7/changes.html
7. https://gcc.gnu.org/onlinedocs/7.3.0/
8. https://gcc.gnu.org/gcc-7/changes.html
9. https://gcc.gnu.org/onlinedocs/7.2.0/
10. https://gcc.gnu.org/gcc-7/changes.html
11. https://gcc.gnu.org/onlinedocs/7.1.0/
12. https://gcc.gnu.org/gcc-7/buildstat.html
13. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
14. https://gcc.gnu.org/index.html
15. mailto:[email protected]
16. https://gcc.gnu.org/mirrors.html
17. https://gcc.gnu.org/git.html
18. https://gcc.gnu.org/onlinedocs/
19. mailto:[email protected]
20. mailto:[email protected]
21. https://gcc.gnu.org/lists.html
22. https://www.fsf.org/
23. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-7/changes.html

GCC 7 Release Series
Changes, New Features, and Fixes

This page is a brief summary of some of the huge number of improvements
in GCC 7. For more information, see the [1]Porting to GCC 7 page and
the [2]full GCC documentation.

Caveats

* GCC now uses [3]LRA (a new local register allocator) by default for
new targets.
* The non-standard C++0x type traits has_trivial_default_constructor,
has_trivial_copy_constructor and has_trivial_copy_assign have been
removed.
* The libstdc++ [4]Profile Mode has been deprecated and will be
removed in a future version.
* The Cilk+ extensions to the C and C++ languages have been
deprecated.
* On ARM targets (arm*-*-*), [5]a bug introduced in GCC 5 that
affects conformance to the procedure call standard (AAPCS) has been
fixed. The bug affects some C++ code where class objects are passed
by value to functions and could result in incorrect or inconsistent
code being generated. This is an ABI change. If the option -Wpsabi
is enabled (on by default) the compiler will emit a diagnostic note
for code that might be affected.

[6]General Optimizer Improvements

* GCC 7 can determine the return value or range of return values of
some calls to the sprintf family of functions and make it available
to other optimization passes. Some calls to the snprintf function
with a zero size argument can be folded into constants. This
optimization is included in -O1 and can be selectively controlled
by the -fprintf-return-value option.
* A new store merging pass has been added. It merges constant stores
to adjacent memory locations into fewer, wider, stores. It is
enabled by the -fstore-merging option and at the -O2 optimization
level or higher (and -Os).
* A new code hoisting optimization has been added to the partial
redundancy elimination pass. It attempts to move evaluation of
expressions executed on all paths to the function exit as early as
possible. This primarily helps improve code size, but can improve
the speed of the generated code as well. It is enabled by the
-fcode-hoisting option and at the -O2 optimization level or higher
(and -Os).
* A new interprocedural bitwise constant propagation optimization has
been added, which propagates knowledge about which bits of
variables are known to be zero (including pointer alignment
information) across the call graph. It is enabled by the
-fipa-bit-cp option if -fipa-cp is enabled as well, and is enabled
at the -O2 optimization level and higher (and -Os). This
optimization supersedes interprocedural alignment propagation of
GCC 6, and therefore the option -fipa-cp-alignment is now
deprecated and ignored.
* A new interprocedural value range propagation optimization has been
added, which propagates integral range information across the call
graph when variable values can be proven to be within those ranges.
It is enabled by the -fipa-vrp option and at the -O2 optimization
level and higher (and -Os).
* A new loop splitting optimization pass has been added. Certain
loops which contain a condition that is always true on one side of
the iteration space and always false on the other are split into
two loops, such that each of the two new loops iterates on just one
side of the iteration space and the condition does not need to be
checked inside of the loop. It is enabled by the -fsplit-loops
option and at the -O3 optimization level or higher.
* The shrink-wrapping optimization can now separate portions of
prologues and epilogues to improve performance if some of the work
done traditionally by prologues and epilogues is not needed on
certain paths. This is controlled by the -fshrink-wrap-separate
option, enabled by default. It requires target support, which is
currently only implemented in the PowerPC and AArch64 ports.
* AddressSanitizer gained a new sanitization option,
-fsanitize-address-use-after-scope, which enables sanitization of
variables whose address is taken and used after a scope where the
variable is defined:

int
main (int argc, char **argv)
{
char *ptr;
{
char my_char;
ptr = &my_char;
}

*ptr = 123;
return *ptr;
}

==28882==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7fffb8dba99
0 at pc 0x0000004006d5 bp 0x7fffb8dba960 sp 0x7fffb8dba958
WRITE of size 1 at 0x7fffb8dba990 thread T0
#0 0x4006d4 in main /tmp/use-after-scope-1.c:10
#1 0x7f9c71943290 in __libc_start_main (/lib64/libc.so.6+0x20290)
#2 0x400739 in _start (/tmp/a.out+0x400739)

Address 0x7fffb8dba990 is located in stack of thread T0 at offset 32 in frame
#0 0x40067f in main /tmp/use-after-scope-1.c:3

This frame has 1 object(s):
[32, 33) 'my_char' <== Memory access at offset 32 is inside this variable

The option is enabled by default with -fsanitize=address and
disabled by default with -fsanitize=kernel-address. Compared to the
LLVM compiler, where the option already exists, the implementation
in the GCC compiler has some improvements and advantages:
+ Complex uses of gotos and case labels are properly handled and
should not report any false positive or false negatives.
+ C++ temporaries are sanitized.
+ Sanitization can handle invalid memory stores that are
optimized out by the LLVM compiler when optimization is
enabled.
* The -fsanitize=signed-integer-overflow suboption of the
UndefinedBehavior Sanitizer now diagnoses arithmetic overflows even
on arithmetic operations with generic vectors.
* Version 5 of the DWARF debugging information standard is supported
through the -gdwarf-5 option. The DWARF version 4 debugging
information remains the default until consumers of debugging
information are adjusted.

[7]New Languages and Language specific improvements

OpenACC support in C, C++, and Fortran continues to be maintained and
improved. See the [8]OpenACC and [9]Offloading wiki pages for further
information.

[10]Ada

* On mainstream native platforms, Ada programs no longer require the
stack to be made executable in order to run properly.

[11]BRIG (HSAIL)

Support for processing BRIG 1.0 files was added in this release. BRIG
is a binary format for HSAIL (Heterogeneous System Architecture
Intermediate Language). The BRIG front end can be used for implementing
HSAIL "finalizers" (compilation of HSAIL to a native ISA) for
GCC-supported targets. An implementation of an HSAIL runtime library,
libhsail-rt is also included.

[12]C family

* New command-line options have been added for the C and C++
compilers:
+ -Wimplicit-fallthrough warns when a switch case falls through.
This warning has five different levels. The compiler is able
to parse a wide range of fallthrough comments, depending on
the level. It also handles control-flow statements, such as
ifs. It's possible to suppress the warning by either adding a
fallthrough comment, or by using a null statement:
__attribute__ ((fallthrough)); (C, C++), or [[fallthrough]];
(C++17), or [[gnu::fallthrough]]; (C++11/C++14). This warning
is enabled by -Wextra.
+ -Wpointer-compare warns when a pointer is compared with a zero
character constant. Such code is now invalid in C++11 and GCC
rejects it. This warning is enabled by default.
+ -Wduplicated-branches warns when an if-else has identical
branches.
+ -Wrestrict warns when an argument passed to a
restrict-qualified parameter aliases with another argument.
+ -Wmemset-elt-size warns for memset calls, when the first
argument references an array, and the third argument is a
number equal to the number of elements of the array, but not
the size of the array. This warning is enabled by -Wall.
+ -Wint-in-bool-context warns about suspicious uses of integer
values where boolean values are expected. This warning is
enabled by -Wall.
+ -Wswitch-unreachable warns when a switch statement has
statements between the controlling expression and the first
case label which will never be executed. This warning is
enabled by default.
+ -Wexpansion-to-defined warns when defined is used outside #if.
This warning is enabled by -Wextra or -Wpedantic.
+ -Wregister warns about uses of the register storage specifier.
In C++17 this keyword has been removed and for C++17 this is a
pedantic warning enabled by default. The warning is not
emitted for the GNU Explicit Register Variables extension.
+ -Wvla-larger-than=N warns about unbounded uses of
variable-length arrays, and about bounded uses of
variable-length arrays whose bound can be larger than N bytes.
+ -Wduplicate-decl-specifier warns when a declaration has
duplicate const, volatile, restrict or _Atomic specifier. This
warning is enabled by -Wall.
* GCC 6's C and C++ front ends were able to offer suggestions for
misspelled field names:

spellcheck-fields.cc:52:13: error: 'struct s' has no member named 'colour'; did
you mean 'color'?
return ptr->colour;
^~~~~~

GCC 7 greatly expands the scope of these suggestions. Firstly, it
adds fix-it hints to such suggestions:

spellcheck-fields.cc:52:13: error: 'struct s' has no member named 'colour'; did
you mean 'color'?
return ptr->colour;
^~~~~~
color

The suggestions now cover many other things, such as misspelled
function names:

spellcheck-identifiers.c:11:3: warning: implicit declaration of function 'gtk_wi
dget_showall'; did you mean 'gtk_widget_show_all'? [-Wimplicit-function-declarat
ion]
gtk_widget_showall (w);
^~~~~~~~~~~~~~~~~~
gtk_widget_show_all

misspelled macro names and enum values:

spellcheck-identifiers.cc:85:11: error: 'MAX_ITEM' undeclared here (not in a fun
ction); did you mean 'MAX_ITEMS'?
int array[MAX_ITEM];
^~~~~~~~
MAX_ITEMS

misspelled type names:

spellcheck-typenames.c:7:14: error: unknown type name 'singed'; did you mean 'si
gned'?
void test (singed char e);
^~~~~~
signed

and, in the C front end, named initializers:

test.c:7:20: error: 'struct s' has no member named 'colour'; did you mean 'color
'?
struct s test = { .colour = 3 };
^~~~~~
color

* The preprocessor can now offer suggestions for misspelled
directives, e.g.:

test.c:5:2: error:invalid preprocessing directive #endfi; did you mean #endif?
#endfi
^~~~~
endif

* Warnings about format strings now underline the pertinent part of
the string, and can offer suggested fixes. In some cases, the
pertinent argument is underlined.

test.c:51:29: warning: format '%s' expects argument of type 'char *', but argume
nt 3 has type 'int' [-Wformat=]
printf ("foo: %d bar: %s baz: %d", 100, i + j, 102);
~^ ~~~~~
%d

* The new -Wdangling-else command-line option has been split out of
-Wparentheses and warns about dangling else.
* The -Wshadow warning has been split into three variants.
-Wshadow=global warns for any shadowing. This is the default when
using -Wshadow without any argument. -Wshadow=local only warns for
a local variable shadowing another local variable or parameter.
-Wshadow=compatible-local only warns for a local variable shadowing
another local variable or parameter whose type is compatible (in
C++ compatible means that the type of the shadowing variable can be
converted to that of the shadowed variable).
The following example shows the different kinds of shadow warnings:

enum operation { add, count };
struct container { int nr; };

int
container_count (struct container c, int count)
{
int r = 0;
for (int count = 0; count > 0; count--)
{
struct container count = c;
r += count.nr;
}
return r;
}

-Wshadow=compatible-local will warn for the parameter being
shadowed with the same type:

warn-test.c:8:12: warning: declaration of 'count' shadows a parameter [-Wshadow=
compatible-local]
for (int count = 0; count > 0; count--)
^~~~~
warn-test.c:5:42: note: shadowed declaration is here
container_count (struct container c, int count)
^~~~~

-Wshadow=local will warn for the above and for the shadowed
declaration with incompatible type:

warn-test.c:10:24: warning: declaration of 'count' shadows a previous local [-Ws
hadow=local]
struct container count = c;
^~~~~
warn-test.c:8:12: note: shadowed declaration is here
for (int count = 0; count > 0; count--)
^~~~~

-Wshadow=global will warn for all of the above and the shadowing of
the global declaration:

warn-test.c:5:42: warning: declaration of 'count' shadows a global declaration [
-Wshadow]
container_count (struct container c, int count)
^~~~~
warn-test.c:1:23: note: shadowed declaration is here
enum operation { add, count };
^~~~~

* GCC 7 contains a number of enhancements that help detect buffer
overflow and other forms of invalid memory accesses.
+ The -Walloc-size-larger-than=size option detects calls to
standard and user-defined memory allocation functions
decorated with attribute alloc_size whose argument exceeds the
specified size (PTRDIFF_MAX by default). The option also
detects arithmetic overflow in the computation of the size in
two-argument allocation functions like calloc where the total
size is the product of the two arguments. Since calls with an
excessive size cannot succeed they are typically the result of
programming errors. Such bugs have been known to be the source
of security vulnerabilities and a target of exploits.
-Walloc-size-larger-than=PTRDIFF_MAX is included in -Wall.
For example, the following call to malloc incorrectly tries to
avoid passing a negative argument to the function and instead
ends up unconditionally invoking it with an argument less than
or equal to zero. Since after conversion to the type of the
argument of the function (size_t) a negative argument results
in a value in excess of the maximum PTRDIFF_MAX the call is
diagnosed.

void* f (int n)
{
return malloc (n > 0 ? 0 : n);
}

warning: argument 1 range [2147483648, 4294967295] exceeds maximum object size 2
147483647 [-Walloc-size-larger-than=]

+ The -Walloc-zero option detects calls to standard and
user-defined memory allocation functions decorated with
attribute alloc_size with a zero argument. -Walloc-zero is not
included in either -Wall or -Wextra and must be explicitly
enabled.
+ The -Walloca option detects all calls to the alloca function
in the program. -Walloca is not included in either -Wall or
-Wextra and must be explicitly enabled.
+ The -Walloca-larger-than=size option detects calls to the
alloca function whose argument either may exceed the specified
size, or that is not known to be sufficiently constrained to
avoid exceeding it. -Walloca-larger-than is not included in
either -Wall or -Wextra and must be explicitly enabled.
For example, compiling the following snippet with
-Walloca-larger-than=1024 results in a warning because even
though the code appears to call alloca only with sizes of 1kb
and less, since n is signed, a negative value would result in
a call to the function well in excess of the limit.

void f (int n)
{
char *d;
if (n < 1025)
d = alloca (n);
else
d = malloc (n);
...
}

warning: argument to 'alloca may be too large due to conversion from 'int' to 'l
ong unsigned int' [-Walloca-larger-than=]

In contrast, a call to alloca that isn't bounded at all such
as in the following function will elicit the warning below
regardless of the size argument to the option.

void f (size_t n)
{
char *d = alloca (n);
...
}

warning: unbounded use of 'alloca' [-Walloca-larger-than=]

+ The -Wformat-overflow=level option detects certain and likely
buffer overflow in calls to the sprintf family of formatted
output functions. Although the option is enabled even without
optimization it works best with -O2 and higher.
For example, in the following snippet the call to sprintf is
diagnosed because even though its output has been constrained
using the modulo operation it could result in as many as three
bytes if mday were negative. The solution is to either
allocate a larger buffer or make sure the argument is not
negative, for example by changing mday's type to unsigned or
by making the type of the second operand of the modulo
expression unsigned: 100U.

void* f (int mday)
{
char *buf = malloc (3);
sprintf (buf, "%02i", mday % 100);
return buf;
}

warning: 'sprintf may write a terminating nul past the end of the destination [-
Wformat-overflow=]
note: 'sprintf' output between 3 and 4 bytes into a destination of size 3

+ The -Wformat-truncation=level option detects certain and
likely output truncation in calls to the snprintf family of
formatted output functions. -Wformat-truncation=1 is included
in -Wall and enabled without optimization but works best with
-O2 and higher.
For example, the following function attempts to format an
integer between 0 and 255 in hexadecimal, including the 0x
prefix, into a buffer of four characters. But since the
function must always terminate output by the null character
('\0') such a buffer is only big enough to fit just one digit
plus the prefix. Therefore the snprintf call is diagnosed. To
avoid the warning either use a bigger buffer or handle the
function's return value which indicates whether or not its
output has been truncated.

void f (unsigned x)
{
char d[4];
snprintf (d, sizeof d, "%#02x", x & 0xff);
...
}

warning: 'snprintf' output may be truncated before the last format character [-W
format-truncation=]
note: 'snprintf' output between 3 and 5 bytes into a destination of size 4

+ The -Wnonnull option has been enhanced to detect a broader set
of cases of passing null pointers to functions that expect a
non-null argument (those decorated with attribute nonnull). By
taking advantage of optimizations the option can detect many
more cases of the problem than in prior GCC versions.
+ The -Wstringop-overflow=type option detects buffer overflow in
calls to string handling functions like memcpy and strcpy. The
option relies on [13]Object Size Checking and has an effect
similar to defining the _FORTIFY_SOURCE macro.
-Wstringop-overflow=2 is enabled by default.
For example, in the following snippet, because the call to
strncat specifies a maximum that allows the function to write
past the end of the destination, it is diagnosed. To correct
the problem and avoid the overflow the function should be
called with a size of at most sizeof d - strlen(d) - 1.

void f (const char *fname)
{
char d[8];
strncpy (d, "/tmp/", sizeof d);
strncat (d, fname, sizeof d);
...
}

warning: specified bound 8 equals the size of the destination [-Wstringop-overfl
ow=]

* The <limits.h> header provided by GCC defines macros such as
INT_WIDTH for the width in bits of integer types, if
__STDC_WANT_IEC_60559_BFP_EXT__ is defined before the header is
included. The <stdint.h> header defines such macros as SIZE_WIDTH
and INTMAX_WIDTH for the width of some standard typedef names for
integer types, again if __STDC_WANT_IEC_60559_BFP_EXT__ is defined
before the header is included; note that GCC's implementation of
this header is only used for freestanding compilations, not hosted
compilations, on most systems. These macros come from ISO/IEC TS
18661-1:2014.
* The <float.h> header provided by GCC defines the macro
CR_DECIMAL_DIG, from ISO/IEC TS 18661-1:2014, if
__STDC_WANT_IEC_60559_BFP_EXT__ is defined before the header is
included. This represents the number of decimal digits for which
conversions between decimal character strings and binary formats,
in both directions, are correctly rounded, and currently has the
value of UINTMAX_MAX on all systems, reflecting that GCC's
compile-time conversions are correctly rounded for any number of
digits.
* New __builtin_add_overflow_p, __builtin_sub_overflow_p,
__builtin_mul_overflow_p built-in functions have been added. These
work similarly to their siblings without the _p suffix, but do not
actually store the result of the arithmetics anywhere, just return
whether the operation would overflow. Calls to these built-ins with
integer constant arguments evaluate to integer constants
expressions.
For example, in the following, c is assigned the result of a * b
only if the multiplication does not overflow, otherwise it is
assigned the value zero. The multiplication is performed at
compile-time and without triggering a -Woverflow warning.

enum {
a = 12345678,
b = 87654321,
c = __builtin_mul_overflow_p (a, b, a) ? 0 : a * b
};

[14]C

* The C front end now supports type names _FloatN for floating-point
types with IEEE interchange formats and _FloatNx for floating-point
types with IEEE extended formats. These type names come from
ISO/IEC TS 18661-3:2015.
The set of types supported depends on the target for which GCC is
configured. Most targets support _Float32, _Float32x and _Float64.
_Float128 is supported on targets where IEEE binary128 encoding was
already supported as long double or __float128. _Float64x is
supported on targets where a type with either binary128 or Intel
extended precision format is available.
Constants with these types are supported using suffixes fN, FN, fNx
and FNx (e.g., 1.2f128 or 2.3F64x). Macros such as FLT128_MAX are
defined in <float.h> if __STDC_WANT_IEC_60559_TYPES_EXT__ is
defined before it is included.
These new types are always distinct from each other and from float,
double and long double, even if they have the same encoding.
Complex types such as _Complex _Float128 are also supported.
Type-generic built-in functions such as __builtin_isinf support the
new types, and the following type-specific built-in functions have
versions (suffixed fN or fNx) for the new types:
__builtin_copysign, __builtin_fabs, __builtin_huge_val,
__builtin_inf, __builtin_nan, __builtin_nans.
* Compilation with -fopenmp is now compatible with the C11 _Atomic
keyword.

[15]C++

* The C++ front end has experimental support for all of the current
C++17 draft with the -std=c++1z or -std=gnu++1z flags, including if
constexpr, class template argument deduction, auto template
parameters, and structured bindings. For a full list of new
features, see [16]the C++ status page.
* C++17 support for new of over-aligned types can be enabled in other
modes with the -faligned-new flag.
* The C++17 evaluation order requirements can be selected in other
modes with the -fstrong-eval-order flag, or disabled in C++17 mode
with -fno-strong-eval-order.
* The default semantics of inherited constructors has changed in all
modes, following [17]P0136. Essentially, overload resolution
happens as if calling the inherited constructor directly, and the
compiler fills in construction of the other bases and members as
needed. Most uses should not need any changes. The old behavior can
be restored with -fno-new-inheriting-ctors, or -fabi-version less
than 11.
* The resolution of DR 150 on matching of template template
parameters, allowing default template arguments to make a template
match a parameter, is currently enabled by default in C++17 mode
only. The default can be overridden with -f{no-,}new-ttp-matching.
* The C++ front end will now provide fix-it hints for some missing
semicolons, allowing for automatic fixes by IDEs:

test.cc:4:11: error: expected ';' after class definition
class a {}
^
;

* -Waligned-new has been added to the C++ front end. It warns about
new of type with extended alignment without -faligned-new.

[18]Runtime Library (libstdc++)

* The type of exception thrown by iostreams, std::ios_base::failure,
now uses the [19]cxx11 ABI.
* Experimental support for C++17, including the following new
features:
+ std::string_view;
+ std::any, std::optional, and std::variant;
+ std::invoke, std::is_invocable, std::is_nothrow_invocable, and
invoke_result;
+ std::is_swappable, and std::is_nothrow_swappable;
+ std::apply, and std::make_from_tuple;
+ std::void_t, std::bool_constant, std::conjunction,
std::disjunction, and std::negation;
+ Variable templates for type traits;
+ Mathematical Special Functions;
+ std::chrono::floor, std::chrono::ceil, std::chrono::round, and
std::chrono::abs;
+ std::clamp, std::gcd, std::lcm, 3-dimensional std::hypot;
+ std::scoped_lock, std::shared_mutex,
std::atomic<T>::is_always_lock_free;
+ std::sample, std::default_searcher, std::boyer_moore_searcher
and std::boyer_moore_horspool_searcher;
+ Extraction and re-insertion of map and set nodes, try_emplace
members for maps, and functions for accessing containers
std::size, std::empty, and std::data;
+ std::shared_ptr support for arrays,
std::shared_ptr<T>::weak_type,
std::enable_shared_from_this<T>::weak_from_this(), and
std::owner_less<void>;
+ std::byte;
+ std::as_const, std::not_fn,
std::has_unique_object_representations, constexpr
std::addressof.
Thanks to Daniel Kr�gler, Tim Shen, Edward Smith-Rowland, and Ville
Voutilainen for work on the C++17 support.
* A new power-of-two rehashing policy for use with the _Hashtable
internals, thanks to Fran�ois Dumont.

[20]Fortran

* Support for a number of extensions for compatibility with legacy
code with new flags:
+ -fdec-structure Support for DEC STRUCTURE and UNION
+ -fdec-intrinsic-ints Support for new integer intrinsics with
B/I/J/K prefixes such as BABS, JIAND...
+ -fdec-math Support for additional math intrinsics, including
COTAN and degree-valued trigonometric functions such as TAND,
ASIND...
+ -fdec Enable the -fdec-* family of extensions.
* New flag -finit-derived to allow default initialization of
derived-type variables.
* Improved DO loops with step equal to 1 or -1, generates faster code
without a loop preheader. A new warning, -Wundefined-do-loop, warns
when a loop iterates either to HUGE(i) (with step equal to 1), or
to -HUGE(i) (with step equal to -1). Invalid behavior can be caught
at run time with -fcheck=do enabled:

program test
implicit none
integer(1) :: i
do i = -HUGE(i)+10, -HUGE(i)-1, -1
print *, i
end do
end program test

At line 8 of file do_check_12.f90
Fortran runtime error: Loop iterates infinitely

* Version 4.5 of the [21]OpenMP specification is now partially
supported in the Fortran compiler; the largest missing item is
structure element mapping.
* User-defined derived-type input/output (UDTIO) is added.
* Derived type coarrays with allocatable and pointer components are
partially supported.
* Non-constant stop codes and error stop codes (Fortran 2015
feature).
* Derived types with allocatable components of recursive type.
* Intrinsic assignment to polymorphic variables.
* Improved submodule support.
* Improved diagnostics (polymorphic results in pure functions).
* Coarray: Support for failed images (Fortan 2015 feature).

[22]Go

* GCC 7 provides a complete implementation of the Go 1.8.1 user
packages.
* Compared to the Go 1.8.1 toolchain, the garbage collector is more
conservative and less concurrent.
* Escape analysis is available for experimental use via the
-fgo-optimize-allocs option. The -fgo-debug-escape prints
information useful for debugging escape analysis choices.

[23]Java (GCJ)

The GCC Java front end and associated libjava runtime library have been
removed from GCC.

[24]libgccjit

The libgccjit API gained support for marking calls as requiring
tail-call optimization via a new entry point:
[25]gcc_jit_rvalue_set_bool_require_tail_call.

libgccjit performs numerous checks at the API boundary, but if these
succeed, it previously ignored errors and other diagnostics emitted
within the core of GCC, and treated the compile of a gcc_jit_context as
having succeeded. As of GCC 7 it now ensures that if any diagnostics
are emitted, they are visible from the libgccjit API, and that the the
context is flagged as having failed.

[26]New Targets and Target Specific Improvements

[27]AArch64

* GCC has been updated to the latest revision of the procedure call
standard (AAPCS64) to provide support for parameter passing when
data types have been over-aligned.
* The ARMv8.3-A architecture is now supported. It can be used by
specifying the -march=armv8.3-a option.
* The option -msign-return-address= is supported to enable return
address protection using ARMv8.3-A Pointer Authentication
Extensions. For more information on the arguments accepted by this
option, please refer to [28]AArch64-Options.
* The ARMv8.2-A architecture and the ARMv8.2-A 16-bit Floating-Point
Extensions are now supported. They can be used by specifying the
-march=armv8.2-a or -march=armv8.2-a+fp16 options. The 16-bit
Floating-Point Extensions introduce new half-precision data
processing floating-point instructions.
* Support has been added for the following processors (GCC
identifiers in parentheses): ARM Cortex-A73 (cortex-a73), Broadcom
Vulcan (vulcan), Cavium ThunderX CN81xx (thunderxt81), Cavium
ThunderX CN83xx (thunderxt83), Cavium ThunderX CN88xx
(thunderxt88), Cavium ThunderX CN88xx pass 1.x (thunderxt88p1),
Cavium ThunderX 2 CN99xx (thunderx2t99), Qualcomm Falkor (falkor).
The GCC identifiers can be used as arguments to the -mcpu or -mtune
options, for example: -mcpu=cortex-a73 or -mtune=vulcan or as
arguments to the equivalent target attributes and pragmas.

[29]ARC

* Added support for ARC HS and ARC EM processors.
* Added support for ARC EM variation found in Intel QuarkSE SoCs.
* Added support for NPS400 ARC700 based CPUs.
* Thread Local Storage is now supported by ARC CPUs.
* Fixed errors for ARC600 when using 32x16 multiplier option.
* Fixed PIE for ARC CPUs.
* New CPU templates are supported via multilib.

[30]ARM

* Support for the ARMv5 and ARMv5E architectures has been deprecated
(which have no known implementations) and will be removed in a
future GCC release. Note that ARMv5T, ARMv5TE and ARMv5TEJ
architectures remain supported. The values armv5 and armv5e of
-march are thus deprecated.
* The ARMv8.2-A architecture and the ARMv8.2-A 16-bit Floating-Point
Extensions are now supported. They can be used by specifying the
-march=armv8.2-a or -march=armv8.2-a+fp16 options. The 16-bit
Floating-Point Extensions introduce new half-precision data
processing floating-point instructions.
* The ARMv8-M architecture is now supported in its two architecture
profiles: ARMv8-M Baseline and ARMv8-M Mainline with its DSP and
Floating-Point Extensions. They can be used by specifying the
-march=armv8-m.base, armv8-m.main or armv8-m.main+dsp options.
* Support has been added for the following processors (GCC
identifiers in parentheses): ARM Cortex-A73 (cortex-a73), ARM
Cortex-M23 (cortex-m23) and ARM Cortex-M33 (cortex-m33). The GCC
identifiers can be used as arguments to the -mcpu or -mtune
options, for example: -mcpu=cortex-a73 or -mtune=cortex-m33.
* A new command-line option -mpure-code has been added. It does not
allow constant data to be placed in code sections. This option is
only available when generating non-PIC code for ARMv7-M targets.
* Support for the ACLE Coprocessor Intrinsics has been added. This
enables the generation of coprocessor instructions through the use
of intrinsics such as cdp, ldc, and others.
* The configure option --with-multilib-list now accepts the value
rmprofile to build multilib libraries for a range of embedded
targets. See our [31]installation instructions for details.

[32]AVR

* On the reduced Tiny cores, the progmem [33]variable attribute is
now properly supported. Respective read-only variables are located
in flash memory in section .progmem.data. No special code is needed
to access such variables; the compiler automatically adds an offset
of 0x4000 to all addresses, which is needed to access variables in
flash memory. As opposed to ordinary cores where it is sufficient
to specify the progmem attribute with definitions, on the reduced
Tiny cores the attribute also has to be specified with (external)
declarations:

extern const int array[] __attribute__((__progmem__));

int get_value2 (void)
{
/* Access via addresses array + 0x4004 and array + 0x4005. */
return array[2];
}

const int* get_address (unsigned idx)
{
/* Returns array + 0x4000 + 2 * idx. */
return &array[idx];
}

* A new command-line option -Wmisspelled-isr has been added. It turns
off -- or turns into errors -- warnings that are reported for
interrupt service routines (ISRs) which don't follow AVR-LibC's
naming convention of prefixing ISR names with __vector.
* __builtin_avr_nops(n) is a new [34]built-in function that inserts n
NOP instructions into the instruction stream. n must be a value
known at compile time.

[35]IA-32/x86-64

* Support for the AVX-512 Fused Multiply Accumulation Packed Single
precision (4FMAPS), AVX-512 Vector Neural Network Instructions Word
variable precision (4VNNIW), AVX-512 Vector Population Count
(VPOPCNTDQ) and Software Guard Extensions (SGX) ISA extensions has
been added.

[36]NVPTX

* OpenMP target regions can now be offloaded to NVidia PTX GPGPUs.
See the [37]Offloading Wiki on how to configure it.

[38]PowerPC / PowerPC64 / RS6000

* The PowerPC port now uses LRA by default.
* GCC now diagnoses inline assembly that clobbers register r2. This
has always been invalid code, and is no longer quietly tolerated.
* The PowerPC port's support for ISA 3.0 (-mcpu=power9) has been
enhanced to generate more of the new instructions by default, and
to provide more built-in functions to generate code for other new
instructions.
* The configuration option --enable-gnu-indirect-function is now
enabled by default on PowerPC GNU/Linux builds.
* The PowerPC port will now allow 64-bit and 32-bit integer types to
be allocated to the VSX vector registers (ISA 2.06 and above). In
addition, on ISA 3.0, 16-bit and 8-bit integer types can be
allocated in the vector registers. Previously, only 64-bit integer
types were allowed in the traditional floating point registers.
* New options -mstack-protector-guard=global,
-mstack-protector-guard=tls, -mstack-protector-guard-reg=, and
-mstack-protector-guard-offset= change how the stack protector gets
the value to use as canary.

[39]S/390, System z, IBM z Systems, IBM Z

* Support for the IBM z14 processor has been added. When using the
-march=z14 option, the compiler will generate code making use of
the new instructions introduced with the vector enhancement
facility and the miscellaneous instruction extension facility 2.
The -mtune=z14 option enables z14 specific instruction scheduling
without making use of new instructions.
* Builtins for the new vector instructions have been added and can be
enabled using the -mzvector option.

[40]RISC-V

* Support for the RISC-V instruction set has been added.

[41]RX

Basic support for atomic built-in function has been added. It is
currently implemented by flipping interrupts off and on as needed.

[42]SH

* Support for SH5/SH64 has been removed.
* Improved utilization of delay slots on SH2A.
* Improved utilization of zero-displacement conditional branches.
* The following deprecated options have been removed
+ -mcbranchdi
+ -mcmpeqdi
+ -minvalid-symbols
+ -msoft-atomic
+ -mspace
+ -madjust-unroll
* Support for the following SH2A instructions has been added
+ mov.b @-Rm,R0
+ mov.w @-Rm,R0
+ mov.l @-Rm,R0
+ mov.b R0,@Rn+
+ mov.w R0,@Rn+
+ mov.l R0,@Rn+

[43]SPARC

* The SPARC port now uses LRA by default.
* Support for the new Subtract-Extended-with-Carry instruction
available in SPARC M7 (Niagara 7) has been added.

[44]Operating Systems

[45]AIX

* Visibility support has been enabled for AIX 7.1 and above.

[46]Fuchsia

* Support has been added for the [47]Fuchsia OS.

[48]RTEMS

* The ABI changes on ARM so that no short enums are used by default.

Other significant improvements

* -fverbose-asm previously emitted information on the meanings of
assembly expressions. This has been extended so that it now also
prints comments showing the source lines that correspond to the
assembly, making it easier to read the generated assembly
(especially with larger functions). For example, given this C
source file:

int test (int n)
{
int i;
int total = 0;

for (i = 0; i < n; i++)
total += i * i;
return total;
}

-fverbose-asm now gives output similar to this for the function
body (when compiling for x86_64, with -Os):

.text
.globl test
.type test, @@function
test:
LFB0:
.cfi_startproc
# example.c:4: int total = 0;
xorl %eax, %eax # <retval>
# example.c:6: for (i = 0; i < n; i++)
xorl %edx, %edx # i
L2:
# example.c:6: for (i = 0; i < n; i++)
cmpl %edi, %edx # n, i
jge .L5 #,
# example.c:7: total += i * i;
movl %edx, %ecx # i, tmp92
imull %edx, %ecx # i, tmp92
# example.c:6: for (i = 0; i < n; i++)
incl %edx # i
# example.c:7: total += i * i;
addl %ecx, %eax # tmp92, <retval>
jmp .L2 #
L5:
# example.c:10: }
ret
.cfi_endproc

* Two new options have been added for printing fix-it hints:
+ -fdiagnostics-parseable-fixits allows for fix-it hints to be
emitted in a machine-readable form, suitable for consumption
by IDEs. For example, given:

spellcheck-fields.cc:52:13: error: 'struct s' has no member named 'colour'; did
you mean 'color'?
return ptr->colour;
^~~~~~
color

it will emit:

fix-it:"spellcheck-fields.cc":{52:13-52:19}:"color"

+ -fdiagnostics-generate-patch will print a patch in "unified"
format after any diagnostics are printed, showing the result
of applying all fix-it hints. For the above example it would
emit:

--- spellcheck-fields.cc
+++ spellcheck-fields.cc
@@ -49,5 +49,5 @@

color get_color(struct s *ptr)
{
- return ptr->colour;
+ return ptr->color;
}

* The gcc and g++ driver programs will now provide suggestions for
misspelled arguments to command-line options.

$ gcc -c test.c -ftls-model=global-dinamic
gcc: error: unknown TLS model 'global-dinamic'
gcc: note: valid arguments to '-ftls-model=' are: global-dynamic initial-exec lo
cal-dynamic local-exec; did you mean 'global-dynamic'?

* The compiler will now provide suggestions for misspelled
parameters.

$ gcc -c test.c --param max-early-inliner-iteration=3
cc1: error: invalid --param name 'max-early-inliner-iteration'; did you mean 'ma
x-early-inliner-iterations'?

* Profile-guided optimization (PGO) instrumentation, as well as test
coverage (GCOV), can newly instrument constructors (functions marks
with __attribute__((constructor))), destructors and C++
constructors (and destructors) of classes that are used as the type
of a global variable.
* A new option -fprofile-update=atomic prevents creation of corrupted
profiles created during an instrumentation run (-fprofile=generate)
of an application. The downside of the option is a speed penalty.
Providing -pthread on the command line selects atomic profile
updating (when supported by the target).
* GCC's already extensive testsuite has gained some new capabilities,
to further improve the reliability of the compiler:
+ GCC now has an internal unit-testing API and a suite of tests
for programmatic self-testing of subsystems.
+ GCC's C front end has been extended so that it can parse dumps
of GCC's internal representations, allowing for DejaGnu tests
that more directly exercise specific optimization passes. This
covers both the [49]GIMPLE representation (for testing
higher-level optimizations) and the [50]RTL representation,
allowing for more direct testing of lower-level details, such
as register allocation and instruction selection.

[51]GCC 7.1

This is the [52]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 7.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[53]GCC 7.2

This is the [54]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 7.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Target Specific Changes

SPARC

* Support for the SPARC M8 processor has been added.
* The switches -mfix-ut700 and -mfix-gr712rc have been added to work
around an erratum in LEON3FT processors.
* Use of the Floating-point Multiply Single to Double (FsMULd)
instruction can now be controlled by the -mfsmuld and -fno-fsmuld
options.

Operating Systems

RTEMS

* The Ada run-time support uses now thread-local storage (TLS).
* Support for RISC-V has been added.
* Support for 64-bit PowerPC using the ELFv2 ABI with 64-bit long
double has been added.

[55]GCC 7.3

This is the [56]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 7.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Target Specific Changes

SPARC

* Workarounds for the four [57]LEON3FT errata GRLIB-TN-0010..0013
have been added. Relevant errata are activated by the target
specific -mfix-ut699, -mfix-ut700 and -mfix-gr712rc switches.

Operating Systems

RTEMS

* Support has been added for Epiphany target.

[58]GCC 7.4

This is the [59]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 7.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[60]GCC 7.5

This is the [61]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 7.5 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

For questions related to the use of GCC, please consult these web
pages and the [62]GCC manuals. If that fails, the
[63][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [64][email protected]. All of [65]our lists have public
archives.

Copyright (C) [66]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [67]maintained by the GCC team. Last modified
2025-01-31.

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59. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=7.4
60. https://gcc.gnu.org/gcc-7/changes.html#GCC7.5
61. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=7.5
62. https://gcc.gnu.org/onlinedocs/
63. mailto:[email protected]
64. mailto:[email protected]
65. https://gcc.gnu.org/lists.html
66. https://www.fsf.org/
67. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-6/index.html

GCC 6 Release Series

(This release series is no longer supported.)

October 26, 2018

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 6.5.

This release is a bug-fix release, containing fixes for regressions in
GCC 6.4 relative to previous releases of GCC.

Release History

GCC 6.5
October 26, 2018 ([2]changes, [3]documentation)

GCC 6.4
July 4, 2017 ([4]changes, [5]documentation)

GCC 6.3
December 21, 2016 ([6]changes, [7]documentation)

GCC 6.2
August 22, 2016 ([8]changes, [9]documentation)

GCC 6.1
April 27, 2016 ([10]changes, [11]documentation)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [12]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [13]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [14]GCC
project web site or contact the [15]GCC development mailing list.

To obtain GCC please use [16]our mirror sites or [17]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [18]GCC manuals. If that fails, the
[19][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [20][email protected]. All of [21]our lists have public
archives.

Copyright (C) [22]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [23]maintained by the GCC team. Last modified
2024-05-30.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-6/changes.html
3. https://gcc.gnu.org/onlinedocs/6.5.0/
4. https://gcc.gnu.org/gcc-6/changes.html
5. https://gcc.gnu.org/onlinedocs/6.4.0/
6. https://gcc.gnu.org/gcc-6/changes.html
7. https://gcc.gnu.org/onlinedocs/6.3.0/
8. https://gcc.gnu.org/gcc-6/changes.html
9. https://gcc.gnu.org/onlinedocs/6.2.0/
10. https://gcc.gnu.org/gcc-6/changes.html
11. https://gcc.gnu.org/onlinedocs/6.1.0/
12. https://gcc.gnu.org/gcc-6/buildstat.html
13. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
14. https://gcc.gnu.org/index.html
15. mailto:[email protected]
16. https://gcc.gnu.org/mirrors.html
17. https://gcc.gnu.org/git.html
18. https://gcc.gnu.org/onlinedocs/
19. mailto:[email protected]
20. mailto:[email protected]
21. https://gcc.gnu.org/lists.html
22. https://www.fsf.org/
23. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-6/changes.html

GCC 6 Release Series
Changes, New Features, and Fixes

This page is a brief summary of some of the huge number of improvements
in GCC 6. For more information, see the [1]Porting to GCC 6 page and
the [2]full GCC documentation.

Caveats

* The default mode for C++ is now -std=gnu++14 instead of
-std=gnu++98.
* Support for a number of older systems and recently unmaintained or
untested target ports of GCC has been declared obsolete in GCC 6.
Unless there is activity to revive them, the next release of GCC
will have their sources permanently removed.
The following ports for individual systems on particular
architectures have been obsoleted:
+ SH5 / SH64 (sh64-*-*) as announced [3]here.
* The AVR port requires binutils version 2.26.1 or later for the fix
for [4]PR71151 to work.
* The GCC 6.5 release has an accidental ABI incompatibility for
nested std::pair objects, for more details see [5]PR 87822. The bug
causes a layout change for pairs where the first member is also a
pair, e.g. std::pair<std::pair<X, Y>, Z>. The GCC 6 release series
is closed so the bug in GCC 6.5 will not be fixed upstream, but
there is a patch in the bug report to allow it to be fixed by
anybody packaging GCC 6.5 or installing it themselves.

[6]General Optimizer Improvements

* UndefinedBehaviorSanitizer gained a new sanitization option,
-fsanitize=bounds-strict, which enables strict checking of array
bounds. In particular, it enables -fsanitize=bounds as well as
instrumentation of flexible array member-like arrays.
* Type-based alias analysis now disambiguates accesses to different
pointers. This improves precision of the alias oracle by about
20-30% on higher-level C++ programs. Programs doing invalid type
punning of pointer types may now need -fno-strict-aliasing to work
correctly.
* Alias analysis now correctly supports the weakref and alias
attributes. This allows accessing both a variable and its alias in
one translation unit which is common with link-time optimization.
* Value range propagation now assumes that the this pointer in C++
member functions is non-null. This eliminates common null pointer
checks but also breaks some non-conforming code-bases (such as
Qt-5, Chromium, KDevelop). As a temporary work-around
-fno-delete-null-pointer-checks can be used. Wrong code can be
identified by using -fsanitize=undefined.
* Link-time optimization improvements:
+ warning and error attributes are now correctly preserved by
declaration linking and thus -D_FORTIFY_SOURCE=2 is now
supported with -flto.
+ Type merging was fixed to handle C and Fortran
interoperability rules as defined by the Fortran 2008 language
standard.
As an exception, CHARACTER(KIND=C_CHAR) is not inter-operable
with char in all cases because it is an array while char is
scalar. INTEGER(KIND=C_SIGNED_CHAR) should be used instead. In
general, this inter-operability cannot be implemented, for
example on targets where the argument passing convention for
arrays differs from scalars.
+ More type information is now preserved at link time, reducing
the loss of accuracy of the type-based alias analysis compared
to builds without link-time optimization.
+ Invalid type punning on global variables and declarations is
now reported with -Wodr-type-mismatch.
+ The size of LTO object files was reduced by about 11%
(measured by compiling Firefox 46.0).
+ Link-time parallelization (enabled using -flto=n) was
significantly improved by decreasing the size of streamed data
when partitioning programs. The size of streamed IL while
compiling Firefox 46.0 was reduced by 66%.
+ The linker plugin was extended to pass information about the
type of binary produced to the GCC back end. (That can also be
controlled manually by -flinker-output.) This makes it
possible to properly configure the code generator and support
incremental linking. Incremental linking of LTO objects by gcc
-r is now supported for plugin-enabled setups.
There are two ways to perform incremental linking:
1. Linking by ld -r will result in an object file with all
sections from individual object files mechanically
merged. This delays the actual link-time optimization to
the final linking step and thus permits whole program
optimization. Linking the final binary with such object
files is however slower.
2. Linking by gcc -r will lead to link-time optimization and
emit the final binary into the object file. Linking such
an object file is fast but avoids any benefits from whole
program optimization.
GCC 7 will support incremental link-time optimization with gcc
-r.
* Inter-procedural optimization improvements:
+ Basic jump threading is now performed before profile
construction and inline analysis, resulting in more realistic
size and time estimates that drive the heuristics of the
inliner and function cloning passes.
+ Function cloning now more aggressively eliminates unused
function parameters.

[7]New Languages and Language specific improvements

Compared to GCC 5, the GCC 6 release series includes a much improved
implementation of the [8]OpenACC 2.0a specification. Highlights are:
* In addition to single-threaded host-fallback execution, offloading
is supported for nvptx (Nvidia GPUs) on x86_64 and PowerPC 64-bit
little-endian GNU/Linux host systems. For nvptx offloading, with
the OpenACC parallel construct, the execution model allows for an
arbitrary number of gangs, up to 32 workers, and 32 vectors.
* Initial support for parallelized execution of OpenACC kernels
constructs:
+ Parallelization of a kernels region is switched on by
-fopenacc combined with -O2 or higher.
+ Code is offloaded onto multiple gangs, but executes with just
one worker, and a vector length of 1.
+ Directives inside a kernels region are not supported.
+ Loops with reductions can be parallelized.
+ Only kernels regions with one loop nest are parallelized.
+ Only the outer-most loop of a loop nest can be parallelized.
+ Loop nests containing sibling loops are not parallelized.
Typically, using the OpenACC parallel construct gives much better
performance, compared to the initial support of the OpenACC kernels
construct.
* The device_type clause is not supported. The bind and nohost
clauses are not supported. The host_data directive is not supported
in Fortran.
* Nested parallelism (cf. CUDA dynamic parallelism) is not supported.
* Usage of OpenACC constructs inside multithreaded contexts (such as
created by OpenMP, or pthread programming) is not supported.
* If a call to the acc_on_device function has a compile-time constant
argument, the function call evaluates to a compile-time constant
value only for C and C++ but not for Fortran.

See the [9]OpenACC and [10]Offloading wiki pages for further
information.

[11]C family

* Version 4.5 of the [12]OpenMP specification is now supported in the
C and C++ compilers.
* The C and C++ compilers now support attributes on enumerators. For
instance, it is now possible to mark enumerators as deprecated:

enum {
newval,
oldval __attribute__ ((deprecated ("too old")))
};

* Source locations for the C and C++ compilers are now tracked as
ranges, rather than just points, making it easier to identify the
subexpression of interest within a complicated expression. For
example:

test.cc: In function 'int test(int, int, foo, int, int)':
test.cc:5:16: error: no match for 'operator*' (operand types are 'int' and 'foo'
)
return p + q * r * s + t;
~~^~~

In addition, there is now initial support for precise diagnostic
locations within strings:

format-strings.c:3:14: warning: field width specifier '*' expects a matching 'in
t' argument [-Wformat=]
printf("%*d");
^

* Diagnostics can now contain "fix-it hints", which are displayed in
context underneath the relevant source code. For example:

fixits.c: In function 'bad_deref':
fixits.c:11:13: error: 'ptr' is a pointer; did you mean to use '->'?
return ptr.x;
^
->

* The C and C++ compilers now offer suggestions for misspelled field
names:

spellcheck-fields.cc:52:13: error: 'struct s' has no member named 'colour'; did
you mean 'color'?
return ptr->colour;
^~~~~~

* New command-line options have been added for the C and C++
compilers:
+ -Wshift-negative-value warns about left shifting a negative
value.
+ -Wshift-overflow warns about left shift overflows. This
warning is enabled by default. -Wshift-overflow=2 also warns
about left-shifting 1 into the sign bit.
+ -Wtautological-compare warns if a self-comparison always
evaluates to true or false. This warning is enabled by -Wall.
+ -Wnull-dereference warns if the compiler detects paths that
trigger erroneous or undefined behavior due to dereferencing a
null pointer. This option is only active when
-fdelete-null-pointer-checks is active, which is enabled by
optimizations in most targets. The precision of the warnings
depends on the optimization options used.
+ -Wduplicated-cond warns about duplicated conditions in an
if-else-if chain.
+ -Wmisleading-indentation warns about places where the
indentation of the code gives a misleading idea of the block
structure of the code to a human reader. For example, given
[13]CVE-2014-1266:

sslKeyExchange.c: In function 'SSLVerifySignedServerKeyExchange':
sslKeyExchange.c:629:3: warning: this 'if' clause does not guard... [-Wmisleadin
g-indentation]
if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0)
^~
sslKeyExchange.c:631:5: note: ...this statement, but the latter is misleadingly
indented as if it is guarded by the 'if'
goto fail;
^~~~

This warning is enabled by -Wall.
* The C and C++ compilers now emit saner error messages if
merge-conflict markers are present in a source file.

test.c:3:1: error: version control conflict marker in file
<<<<<<< HEAD
^~~~~~~

[14]C

* It is possible to disable warnings when an initialized field of a
structure or a union with side effects is being overridden when
using designated initializers via a new warning option
-Woverride-init-side-effects.
* A new type attribute scalar_storage_order applying to structures
and unions has been introduced. It specifies the storage order (aka
endianness) in memory of scalar fields in structures or unions.

[15]C++

* The default mode has been changed to -std=gnu++14.
* [16]C++ Concepts are now supported when compiling with -fconcepts.
* -flifetime-dse is more aggressive in dead-store elimination in
situations where a memory store to a location precedes a
constructor to that memory location.
* G++ now supports [17]C++17 fold expressions, u8 character literals,
extended static_assert, and nested namespace definitions.
* G++ now allows constant evaluation for all non-type template
arguments.
* G++ now supports C++ Transactional Memory when compiling with
-fgnu-tm.

[18]Runtime Library (libstdc++)

* Extensions to the C++ Library to support mathematical special
functions (ISO/IEC 29124:2010), thanks to Edward Smith-Rowland.
* Experimental support for C++17, including the following new
features:
+ std::uncaught_exceptions function (this is also available for
-std=gnu++NN modes);
+ new member functions try_emplace and insert_or_assign for
unique_key maps;
+ non-member functions std::size, std::empty, and std::data for
accessing containers and arrays;
+ std::invoke;
+ std::shared_mutex;
+ std::void_t and std::bool_constant metaprogramming utilities.
Thanks to Ville Voutilainen for contributing many of the C++17
features.
* An experimental implementation of the File System TS.
* Experimental support for most features of the second version of the
Library Fundamentals TS. This includes polymorphic memory resources
and array support in shared_ptr, thanks to Fan You.
* Some assertions checked by Debug Mode can now also be enabled by
_GLIBCXX_ASSERTIONS. The subset of checks enabled by the new macro
have less run-time overhead than the full _GLIBCXX_DEBUG checks and
don't affect the library ABI, so can be enabled per-translation
unit.
* Timed mutex types are supported on more targets, including Darwin.
* Improved std::locale support for DragonFly and FreeBSD, thanks to
John Marino and Andreas Tobler.

[19]Fortran

* Fortran 2008 SUBMODULE support.
* Fortran 2015 EVENT_TYPE, EVENT_POST, EVENT_WAIT, and EVENT_QUERY
support.
* Improved support for Fortran 2003 deferred-length character
variables.
* Improved support for OpenMP and OpenACC.
* The MATMUL intrinsic is now inlined for straightforward cases if
front-end optimization is active. The maximum size for inlining can
be set to n with the -finline-matmul-limit=n option and turned off
with -finline-matmul-limit=0.
* The -Wconversion-extra option will warn about REAL constants which
have excess precision for their kind.
* The -Winteger-division option has been added, which warns about
divisions of integer constants which are truncated. This option is
included in -Wall by default.

[20]libgccjit

* The driver code is now run in-process within libgccjit, providing a
small speed-up of the compilation process.
* The API has gained entrypoints for
+ [21]timing how long was spent in different parts of code,
+ [22]creating switch statements,
+ [23]allowing unreachable basic blocks in a function, and
+ [24]adding arbitrary command-line options to a compilation.

[25]New Targets and Target Specific Improvements

[26]AArch64

* A number of AArch64-specific options have been added. The most
important ones are summarised in this section; for more detailed
information please refer to the documentation.
* The command-line options -march=native, -mcpu=native and
-mtune=native are now available on native AArch64 GNU/Linux
systems. Specifying these options causes GCC to auto-detect the
host CPU and choose the optimal setting for that system.
* -fpic is now supported when generating code for the small code
model (-mcmodel=small). The size of the global offset table (GOT)
is limited to 28KiB under the LP64 SysV ABI, and 15KiB under the
ILP32 SysV ABI.
* The AArch64 port now supports target attributes and pragmas. Please
refer to the [27]documentation for details of available attributes
and pragmas as well as usage instructions.
* Link-time optimization across translation units with different
target-specific options is now supported.
* The option -mtls-size= is now supported. It can be used to specify
the bit size of TLS offsets, allowing GCC to generate better TLS
instruction sequences.
* The option -fno-plt is now fully functional.
* The ARMv8.1-A architecture and the Large System Extensions are now
supported. They can be used by specifying the -march=armv8.1-a
option. Additionally, the +lse option extension can be used in a
similar fashion to other option extensions. The Large System
Extensions introduce new instructions that are used in the
implementation of atomic operations.
* The ACLE half-precision floating-point type __fp16 is now supported
in the C and C++ languages.
* The ARM Cortex-A35 processor is now supported via the
-mcpu=cortex-a35 and -mtune=cortex-a35 options as well as the
equivalent target attributes and pragmas.
* The Qualcomm QDF24xx processor is now supported via the
-mcpu=qdf24xx and -mtune=qdf24xx options as well as the equivalent
target attributes and pragmas.
* Code generation for the ARM Cortex-A57 processor is improved. Among
general code generation improvements, a better algorithm is added
for allocating registers to floating-point multiply-accumulate
instructions offering increased performance when compiling with
-mcpu=cortex-a57 or -mtune=cortex-a57.
* Code generation for the ARM Cortex-A53 processor is improved. A
more accurate instruction scheduling model for the processor is now
used, and a number of compiler tuning parameters have been set to
offer increased performance when compiling with -mcpu=cortex-a53 or
-mtune=cortex-a53.
* Code generation for the Samsung Exynos M1 processor is improved. A
more accurate instruction scheduling model for the processor is now
used, and a number of compiler tuning parameters have been set to
offer increased performance when compiling with -mcpu=exynos-m1 or
-mtune=exynos-m1.
* Improvements in the generation of conditional branches and literal
pools allow the compiler to compile functions of a large size.
Constant pools are now placed into separate rodata sections. The
new option -mpc-relative-literal-loads generates per-function
literal pools, limiting the maximum size of functions to 1MiB.
* Several correctness issues generating Advanced SIMD instructions
for big-endian targets have been fixed resulting in improved code
generation for ACLE intrinsics with -mbig-endian.

[28]ARM

* Support for revisions of the ARM architecture prior to ARMv4t has
been deprecated and will be removed in a future GCC release. The
-mcpu and -mtune values that are deprecated are: arm2, arm250,
arm3, arm6, arm60, arm600, arm610, arm620, arm7, arm7d, arm7di,
arm70, arm700, arm700i, arm710, arm720, arm710c, arm7100, arm7500,
arm7500fe, arm7m, arm7dm, arm7dmi, arm8, arm810, strongarm,
strongarm110, strongarm1100, strongarm1110, fa526, fa626. The value
arm7tdmi is still supported. The values of -march that are
deprecated are: armv2,armv2a,armv3,armv3m,armv4.
* The ARM port now supports target attributes and pragmas. Please
refer to the [29]documentation for details of available attributes
and pragmas as well as usage instructions.
* Support has been added for the following processors (GCC
identifiers in parentheses): ARM Cortex-A32 (cortex-a32), ARM
Cortex-A35 (cortex-a35) and ARM Cortex-R8 (cortex-r8). The GCC
identifiers can be used as arguments to the -mcpu or -mtune
options, for example: -mcpu=cortex-a32 or -mtune=cortex-a35.

[30]Heterogeneous Systems Architecture

* GCC can now generate HSAIL (Heterogeneous System Architecture
Intermediate Language) for simple OpenMP device constructs if
configured with --enable-offload-targets=hsa. A new libgomp plugin
then runs the HSA GPU kernels implementing these constructs on HSA
capable GPUs via a standard HSA run time.
If the HSA compilation back end determines it cannot output HSAIL
for a particular input, it gives a warning by default. These
warnings can be suppressed with -Wno-hsa. To give a few examples,
the HSA back end does not implement compilation of code using
function pointers, automatic allocation of variable sized arrays,
functions with variadic arguments as well as a number of other less
common programming constructs.
When compilation for HSA is enabled, the compiler attempts to
compile composite OpenMP constructs

#pragma omp target teams distribute parallel for

into parallel HSA GPU kernels.

[31]IA-32/x86-64

* GCC now supports the Intel CPU named Skylake with AVX-512
extensions through -march=skylake-avx512. The switch enables the
following ISA extensions: AVX-512F, AVX512VL, AVX-512CD, AVX-512BW,
AVX-512DQ.
* Support for new AMD instructions monitorx and mwaitx has been
added. This includes new intrinsic and built-in support. It is
enabled through option -mmwaitx. The instructions monitorx and
mwaitx implement the same functionality as the old monitor and
mwait instructions. In addition, mwaitx adds a configurable timer.
The timer value is received as third argument and stored in
register %ebx.
* x86-64 targets now allow stack realignment from a word-aligned
stack pointer using the command-line option -mstackrealign or
__attribute__ ((force_align_arg_pointer)). This allows functions
compiled with a vector-aligned stack to be invoked from objects
that keep only word-alignment.
* Support for address spaces __seg_fs, __seg_gs, and __seg_tls. These
can be used to access data via the %fs and %gs segments without
having to resort to inline assembly. Please refer to the
[32]documentation for usage instructions.
* Support for AMD Zen (family 17h) processors is now available
through the -march=znver1 and -mtune=znver1 options.

[33]MeP

* Support for the MeP (mep-elf) architecture has been deprecated and
will be removed in a future GCC release.

[34]MSP430

* The MSP430 compiler now has the ability to automatically distribute
code and data between low memory (addresses below 64K) and high
memory. This only applies to parts that actually have both memory
regions and only if the linker script for the part has been
specifically set up to support this feature.
A new attribute of either can be applied to both functions and
data, and this tells the compiler to place the object into low
memory if there is room and into high memory otherwise. Two other
new attributes - lower and upper - can be used to explicitly state
that an object should be placed in the specified memory region. If
there is not enough left in that region the compilation will fail.
Two new command-line options - -mcode-region=[lower|upper|either]
and -mdata-region=[lower|upper|either] - can be used to tell the
compiler what to do with objects that do not have one of these new
attributes.

[35]PowerPC / PowerPC64 / RS6000

* PowerPC64 now supports IEEE 128-bit floating-point using the
__float128 data type. In GCC 6, this is not enabled by default, but
you can enable it with -mfloat128. The IEEE 128-bit floating-point
support requires the use of the VSX instruction set. IEEE 128-bit
floating-point values are passed and returned as a single vector
value. The software emulator for IEEE 128-bit floating-point
support is only built on PowerPC GNU/Linux systems where the
default CPU is at least power7. On future ISA 3.0 systems (POWER 9
and later), you will be able to use the -mfloat128-hardware option
to use the ISA 3.0 instructions that support IEEE 128-bit
floating-point. An additional type (__ibm128) has been added to
refer to the IBM extended double type that normally implements long
double. This will allow for a future transition to implementing
long double with IEEE 128-bit floating-point.
* Basic support has been added for POWER9 hardware that will use the
recently published OpenPOWER ISA 3.0 instructions. The following
new switches are available:
+ -mcpu=power9: Implement all of the ISA 3.0 instructions
supported by the compiler.
+ -mtune=power9: In the future, apply tuning for POWER9 systems.
Currently, POWER8 tunings are used.
+ -mmodulo: Generate code using the ISA 3.0 integer instructions
(modulus, count trailing zeros, array index support, integer
multiply/add).
+ -mpower9-fusion: Generate code to suitably fuse instruction
sequences for a POWER9 system.
+ -mpower9-dform: Generate code to use the new D-form
(register+offset) memory instructions for the vector
registers.
+ -mpower9-vector: Generate code using the new ISA 3.0 vector
(VSX or Altivec) instructions.
+ -mpower9-minmax: Reserved for future development.
+ -mtoc-fusion: Keep TOC entries together to provide more fusion
opportunities.
* New constraints have been added to support IEEE 128-bit
floating-point and ISA 3.0 instructions:
+ wb: Altivec register if -mpower9-dform is enabled.
+ we: VSX register if -mpower9-vector is enabled for 64-bit code
generation.
+ wo: VSX register if -mpower9-vector is enabled.
+ wp: Reserved for future use if long double is implemented with
IEEE 128-bit floating-point instead of IBM extended double.
+ wq: VSX register if -mfloat128 is enabled.
+ wF: Memory operand suitable for POWER9 fusion load/store.
+ wG: Memory operand suitable for TOC fusion memory references.
+ wL: Integer constant identifying the element number mfvsrld
accesses within a vector.
* Support has been added for __builtin_cpu_is() and
__builtin_cpu_supports(), allowing for very fast access to
AT_PLATFORM, AT_HWCAP, and AT_HWCAP2 values. This requires use of
glibc 2.23 or later.
* All hardware transactional memory builtins now correctly behave as
memory barriers. Programmers can use #ifdef __TM_FENCE__ to
determine whether their "old" compiler treats the builtins as
barriers.
* Split-stack support has been added for gccgo on PowerPC64 for both
big- and little-endian (but not for 32-bit). The gold linker from
at least binutils 2.25.1 must be available in the PATH when
configuring and building gccgo to enable split stack. (The
requirement for binutils 2.25.1 applies to PowerPC64 only.) The
split-stack feature allows a small initial stack size to be
allocated for each goroutine, which increases as needed.
* GCC on PowerPC now supports the standard lround function.
* A new configuration option ---with-advance-toolchain=at was added
for PowerPC 64-bit GNU/Linux systems to use the header files,
library files, and the dynamic linker from a specific Advance
Toolchain release instead of the default versions that are provided
by the GNU/Linux distribution. In general, this option is intended
for the developers of GCC, and it is not intended for general use.
* The "q", "S", "T", and "t" asm-constraints have been removed.
* The "b", "B", "m", "M", and "W" format modifiers have been removed.

[36]S/390, System z, IBM z Systems

* Support for the IBM z13 processor has been added. When using the
-march=z13 option, the compiler will generate code making use of
the new instructions and registers introduced with the vector
extension facility. The -mtune=z13 option enables z13 specific
instruction scheduling without making use of new instructions.
Compiling code with -march=z13 reduces the default alignment of
vector types bigger than 8 bytes to 8. This is an ABI change and
care must be taken when linking modules compiled with different
arch levels which interchange variables containing vector type
values. For newly compiled code the GNU linker will emit a warning.
* The -mzvector option enables a C/C++ language extension. This
extension provides a new keyword vector which can be used to define
vector type variables. (Note: This is not available when enforcing
strict standard compliance e.g. with -std=c99. Either enable GNU
extensions with e.g. -std=gnu99 or use __vector instead of vector.)
Additionally a set of overloaded builtins is provided which is
partially compatible to the PowerPC Altivec builtins. In order to
make use of these builtins the vecintrin.h header file needs to be
included.
* The new command-line options -march=native, and -mtune=native are
now available on native IBM z Systems. Specifying these options
causes GCC to auto-detect the host CPU and choose the optimal
setting for that system. If GCC is unable to detect the host CPU
these options have no effect.
* The IBM z Systems port now supports target attributes and pragmas.
Please refer to the [37]documentation for details of available
attributes and pragmas as well as usage instructions.
* -fsplit-stack is now supported as part of the IBM z Systems port.
This feature requires a recent gold linker to be used.
* Support for the g5 and g6 -march=/-mtune= CPU level switches has
been deprecated and will be removed in a future GCC release. -m31
from now on defaults to -march=z900 if not specified otherwise.
-march=native on a g5/g6 machine will default to -march=z900.

[38]SH

* Support for SH5 / SH64 has been declared obsolete and will be
removed in future releases.
* Support for the FDPIC ABI has been added. It can be enabled using
the new -mfdpic target option and --enable-fdpic configure option.

[39]SPARC

* An ABI bug has been fixed in 64-bit mode. Unfortunately, this
change will break binary compatibility with earlier releases for
code it affects, but this should be pretty rare in practice. The
conditions are: a 16-byte structure containing a double or a 8-byte
vector in the second half is passed to a subprogram in slot #15,
for example as 16th parameter if the first 15 ones have at most 8
bytes. The double or vector was wrongly passed in floating-point
register %d32 in lieu of on the stack as per the SPARC calling
conventions.

[40]Operating Systems

[41]AIX

* DWARF debugging support for AIX 7.1 has been enabled as an optional
debugging format. A more recent Technology Level (TL) and GCC built
with that level are required for full exploitation of DWARF
debugging capabilities.

[42]Linux

* Support for the [43]musl C library was added for the AArch64, ARM,
MicroBlaze, MIPS, MIPS64, PowerPC, PowerPC64, SH, i386, x32 and
x86_64 targets. It can be selected using the new -mmusl option in
case musl is not the default libc. GCC defaults to musl libc if it
is built with a target triplet matching the *-linux-musl* pattern.

[44]RTEMS

* The RTEMS thread model implementation changed. Mutexes now use
self-contained objects defined in newlib <sys/lock.h> instead of
Classic API semaphores. The keys for thread specific data and the
once function are directly defined via <pthread.h>. Self-contained
condition variables are provided via newlib <sys/lock.h>. The RTEMS
thread model also supports C++11 threads.
* OpenMP support now uses self-contained objects provided by newlib
<sys/lock.h> and offers a significantly better performance compared
to the POSIX configuration of libgomp. It is possible to configure
thread pools for each scheduler instance via the environment
variable GOMP_RTEMS_THREAD_POOLS.

[45]Solaris

* Solaris 12 is now fully supported. Minimal support had already been
present in GCC 5.3.
* Solaris 12 provides a full set of startup files (crt1.o, crti.o,
crtn.o), which GCC now prefers over its own ones.
* Position independent executables (PIE) are now supported on Solaris
12.
* Constructor priority is now supported on Solaris 12 with the system
linker.
* libvtv has been ported to Solaris 11 and up.

[46]Windows

* The option -mstackrealign is now automatically activated in 32-bit
mode whenever the use of SSE instructions is requested.

Other significant improvements

* The gcc and g++ driver programs will now provide suggestions for
misspelled command-line options.

$ gcc -static-libfortran test.f95
gcc: error: unrecognized command line option '-static-libfortran'; did you mean
'-static-libgfortran'?

* The --enable-default-pie configure option enables generation of PIE
by default.

[47]GCC 6.2

This is the [48]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 6.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Target Specific Changes

SPARC

* Support for --with-cpu-32 and --with-cpu-64 configure options has
been added on bi-architecture platforms.
* Support for the SPARC M7 (Niagara 7) processor has been added.
* Support for the VIS 4.0 instruction set has been added.

[49]GCC 6.3

This is the [50]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 6.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Target Specific Changes

IA-32/x86-64

* Support for the [51]deprecated pcommit instruction has been
removed.

[52]GCC 6.4

This is the [53]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 6.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[54]Operating Systems

[55]RTEMS

* The ABI changes on ARM so that no short enums are used by default.

[56]GCC 6.5

This is the [57]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 6.5 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

For questions related to the use of GCC, please consult these web
pages and the [58]GCC manuals. If that fails, the
[59][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [60][email protected]. All of [61]our lists have public
archives.

Copyright (C) [62]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [63]maintained by the GCC team. Last modified
2025-01-31.

References

1. https://gcc.gnu.org/gcc-6/porting_to.html
2. https://gcc.gnu.org/onlinedocs/index.html#current
3. https://gcc.gnu.org/ml/gcc/2015-08/msg00101.html
4. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71151
5. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87822
6. https://gcc.gnu.org/gcc-6/changes.html#general
7. https://gcc.gnu.org/gcc-6/changes.html#languages
8. https://www.openacc.org/
9. https://gcc.gnu.org/wiki/OpenACC
10. https://gcc.gnu.org/wiki/Offloading
11. https://gcc.gnu.org/gcc-6/changes.html#c-family
12. https://www.openmp.org/specifications/
13. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-1266
14. https://gcc.gnu.org/gcc-6/changes.html#c
15. https://gcc.gnu.org/gcc-6/changes.html#cxx
16. https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4377.pdf
17. https://gcc.gnu.org/projects/cxx-status.html#cxx1z
18. https://gcc.gnu.org/gcc-6/changes.html#libstdcxx
19. https://gcc.gnu.org/gcc-6/changes.html#fortran
20. https://gcc.gnu.org/gcc-6/changes.html#jit
21. https://gcc.gnu.org/onlinedocs/gcc-6.1.0/jit/topics/performance.html
22. https://gcc.gnu.org/onlinedocs/gcc-6.1.0/jit/topics/functions.html#gcc_jit_block_end_with_switch
23. https://gcc.gnu.org/onlinedocs/gcc-6.1.0/jit/topics/contexts.html#gcc_jit_context_set_bool_allow_unreachable_blocks
24. https://gcc.gnu.org/onlinedocs/gcc-6.1.0/jit/topics/contexts.html#gcc_jit_context_add_command_line_option
25. https://gcc.gnu.org/gcc-6/changes.html#targets
26. https://gcc.gnu.org/gcc-6/changes.html#aarch64
27. https://gcc.gnu.org/onlinedocs/gcc-6.1.0/gcc/AArch64-Function-Attributes.html#AArch64-Function-Attributes
28. https://gcc.gnu.org/gcc-6/changes.html#arm
29. https://gcc.gnu.org/onlinedocs/gcc-6.1.0/gcc/ARM-Function-Attributes.html#ARM-Function-Attributes
30. https://gcc.gnu.org/gcc-6/changes.html#hsa
31. https://gcc.gnu.org/gcc-6/changes.html#x86
32. https://gcc.gnu.org/onlinedocs/gcc-6.1.0/gcc/Named-Address-Spaces.html#Named-Address-Spaces
33. https://gcc.gnu.org/gcc-6/changes.html#mep
34. https://gcc.gnu.org/gcc-6/changes.html#msp430
35. https://gcc.gnu.org/gcc-6/changes.html#powerpc
36. https://gcc.gnu.org/gcc-6/changes.html#s390
37. https://gcc.gnu.org/onlinedocs/gcc-6.1.0/gcc/S_002f390-Function-Attributes.html#S_002f390-Function-Attributes
38. https://gcc.gnu.org/gcc-6/changes.html#sh
39. https://gcc.gnu.org/gcc-6/changes.html#sparc
40. https://gcc.gnu.org/gcc-6/changes.html#os
41. https://gcc.gnu.org/gcc-6/changes.html#aix
42. https://gcc.gnu.org/gcc-6/changes.html#linux
43. http://www.musl-libc.org/
44. https://gcc.gnu.org/gcc-6/changes.html#rtems
45. https://gcc.gnu.org/gcc-6/changes.html#solaris
46. https://gcc.gnu.org/gcc-6/changes.html#windows
47. https://gcc.gnu.org/gcc-6/changes.html#GCC6.2
48. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=6.2
49. https://gcc.gnu.org/gcc-6/changes.html#GCC6.3
50. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=6.3
51. https://www.intel.com/content/www/us/en/developer/articles/technical/deprecate-pcommit-instruction.html
52. https://gcc.gnu.org/gcc-6/changes.html#GCC6.4
53. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=6.4
54. https://gcc.gnu.org/gcc-6/changes.html#os64
55. https://gcc.gnu.org/gcc-6/changes.html#rtems64
56. https://gcc.gnu.org/gcc-6/changes.html#GCC6.5
57. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=6.5
58. https://gcc.gnu.org/onlinedocs/
59. mailto:[email protected]
60. mailto:[email protected]
61. https://gcc.gnu.org/lists.html
62. https://www.fsf.org/
63. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-5/index.html

GCC 5 Release Series

(This release series is no longer supported.)

October 10, 2017

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 5.5.

This release is a bug-fix release, containing fixes for regressions in
GCC 5.4 relative to previous releases of GCC.

Release History

GCC 5.5
October 10, 2017 ([2]changes, [3]documentation)

GCC 5.4
June 3, 2016 ([4]changes, [5]documentation)

GCC 5.3
December 4, 2015 ([6]changes, [7]documentation)

GCC 5.2
July 16, 2015 ([8]changes, [9]documentation)

GCC 5.1
April 22, 2015 ([10]changes, [11]documentation)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [12]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [13]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [14]GCC
project web site or contact the [15]GCC development mailing list.

To obtain GCC please use [16]our mirror sites or [17]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [18]GCC manuals. If that fails, the
[19][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [20][email protected]. All of [21]our lists have public
archives.

Copyright (C) [22]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [23]maintained by the GCC team. Last modified
2024-05-30.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-5/changes.html
3. https://gcc.gnu.org/onlinedocs/5.5.0/
4. https://gcc.gnu.org/gcc-5/changes.html
5. https://gcc.gnu.org/onlinedocs/5.4.0/
6. https://gcc.gnu.org/gcc-5/changes.html
7. https://gcc.gnu.org/onlinedocs/5.3.0/
8. https://gcc.gnu.org/gcc-5/changes.html
9. https://gcc.gnu.org/onlinedocs/5.2.0/
10. https://gcc.gnu.org/gcc-5/changes.html
11. https://gcc.gnu.org/onlinedocs/5.1.0/
12. https://gcc.gnu.org/gcc-5/buildstat.html
13. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
14. https://gcc.gnu.org/index.html
15. mailto:[email protected]
16. https://gcc.gnu.org/mirrors.html
17. https://gcc.gnu.org/git.html
18. https://gcc.gnu.org/onlinedocs/
19. mailto:[email protected]
20. mailto:[email protected]
21. https://gcc.gnu.org/lists.html
22. https://www.fsf.org/
23. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-5/changes.html

GCC 5 Release Series
Changes, New Features, and Fixes

Caveats

* The default mode for C is now -std=gnu11 instead of -std=gnu89.
* The C++ runtime library (libstdc++) uses a new ABI by default (see
[1]below).
* The Graphite framework for loop optimizations no longer requires
the CLooG library, only ISL version 0.14 (recommended) or 0.12.2.
The installation manual contains more information about
requirements to build GCC.
* The non-standard C++0x type traits has_trivial_default_constructor,
has_trivial_copy_constructor and has_trivial_copy_assign have been
deprecated and will be removed in a future version. The standard
C++11 traits is_trivially_default_constructible,
is_trivially_copy_constructible and is_trivially_copy_assignable
should be used instead.

[2]General Optimizer Improvements

* Inter-procedural optimization improvements:
+ An Identical Code Folding (ICF) pass (controlled via
-fipa-icf) has been added. Compared to the identical code
folding performed by the Gold linker this pass does not
require function sections. It also performs merging before
inlining, so inter-procedural optimizations are aware of the
code re-use. On the other hand not all unifications performed
by a linker are doable by GCC which must honor aliasing
information. During link-time optimization of Firefox, this
pass unifies about 31000 functions, that is 14% overall.
+ The devirtualization pass was significantly improved by adding
better support for speculative devirtualization and dynamic
type detection. About 50% of virtual calls in Firefox are now
speculatively devirtualized during link-time optimization.
+ A new comdat localization pass allows the linker to eliminate
more dead code in presence of C++ inline functions.
+ Virtual tables are now optimized. Local aliases are used to
reduce dynamic linking time of C++ virtual tables on ELF
targets and data alignment has been reduced to limit data
segment bloat.
+ A new -fno-semantic-interposition option can be used to
improve code quality of shared libraries where interposition
of exported symbols is not allowed.
+ Write-only variables are now detected and optimized out.
+ With profile feedback the function inliner can now bypass
--param inline-insns-auto and --param inline-insns-single
limits for hot calls.
+ The IPA reference pass was significantly sped up making it
feasible to enable -fipa-reference with -fprofile-generate.
This also solves a bottleneck seen when building Chromium with
link-time optimization.
+ The symbol table and call-graph API was reworked to C++ and
simplified.
+ The interprocedural propagation of constants now also
propagates alignments of pointer parameters. This for example
means that the vectorizer often does not need to generate loop
prologues and epilogues to make up for potential
misalignments.
* Link-time optimization improvements:
+ One Definition Rule based merging of C++ types has been
implemented. Type merging enables better devirtualization and
alias analysis. Streaming extra information needed to merge
types adds about 2-6% of memory size and object size increase.
This can be controlled by -flto-odr-type-merging.
+ Command-line optimization and target options are now streamed
on a per-function basis and honored by the link-time
optimizer. This change makes link-time optimization a more
transparent replacement of per-file optimizations. It is now
possible to build projects that require different optimization
settings for different translation units (such as -ffast-math,
-mavx, or -finline). Contrary to earlier GCC releases, the
optimization and target options passed on the link command
line are ignored.
Note that this applies only to those command-line options that
can be passed to optimize and target attributes. Command-line
options affecting global code generation (such as -fpic),
warnings (such as -Wodr), optimizations affecting the way
static variables are optimized (such as -fcommon), debug
output (such as -g), and --param parameters can be applied
only to the whole link-time optimization unit. In these cases,
it is recommended to consistently use the same options at both
compile time and link time.
+ GCC bootstrap now uses slim LTO object files.
+ Memory usage and link times were improved. Tree merging was
sped up, memory usage of GIMPLE declarations and types was
reduced, and, support for on-demand streaming of variable
constructors was added.
* Feedback directed optimization improvements:
+ A new auto-FDO mode uses profiles collected by low overhead
profiling tools (perf) instead of more expensive program
instrumentation (via -fprofile-generate). SPEC2006 benchmarks
on x86-64 improve by 4.7% with auto-FDO and by 7.3% with
traditional feedback directed optimization.
+ Profile precision was improved in presence of C++ inline and
extern inline functions.
+ The new gcov-tool utility allows manipulating profiles.
+ Profiles are now more tolerant to source file changes (this
can be controlled by --param profile-func-internal-id).
* Register allocation improvements:
+ A new local register allocator (LRA) sub-pass, controlled by
-flra-remat, implements control-flow sensitive global register
rematerialization. Instead of spilling and restoring a
register value, it is recalculated if it is profitable. The
sub-pass improved SPEC2000 generated code by 1% and 0.5%
correspondingly on ARM and x86-64.
+ Reuse of the PIC hard register, instead of using a fixed
register, was implemented on x86/x86-64 targets. This improves
generated PIC code performance as more hard registers can be
used. Shared libraries can significantly benefit from this
optimization. Currently it is switched on only for x86/x86-64
targets. As RA infrastructure is already implemented for PIC
register reuse, other targets might follow this in the future.
+ A simple form of inter-procedural RA was implemented. When it
is known that a called function does not use caller-saved
registers, save/restore code is not generated around the call
for such registers. This optimization can be controlled by
-fipa-ra
+ LRA is now much more effective at generating spills of general
registers into vector registers instead of memory on
architectures (e.g., modern Intel processors) where this is
profitable.
* UndefinedBehaviorSanitizer gained a few new sanitization options:
+ -fsanitize=float-divide-by-zero: detect floating-point
division by zero;
+ -fsanitize=float-cast-overflow: check that the result of
floating-point type to integer conversions do not overflow;
+ -fsanitize=bounds: enable instrumentation of array bounds and
detect out-of-bounds accesses;
+ -fsanitize=alignment: enable alignment checking, detect
various misaligned objects;
+ -fsanitize=object-size: enable object size checking, detect
various out-of-bounds accesses.
+ -fsanitize=vptr: enable checking of C++ member function calls,
member accesses and some conversions between pointers to base
and derived classes, detect if the referenced object does not
have the correct dynamic type.
* Pointer Bounds Checker, a bounds violation detector, has been added
and can be enabled via -fcheck-pointer-bounds. Memory accesses are
instrumented with run-time checks of used pointers against their
bounds to detect pointer bounds violations (overflows). The Pointer
Bounds Checker is available on x86/x86-64 GNU/Linux targets with a
new ISA extension Intel MPX support. See the Pointer Bounds Checker
[3]Wiki page for more details.

[4]New Languages and Language specific improvements

* [5]OpenMP 4.0 specification offloading features are now supported
by the C, C++, and Fortran compilers. Generic changes:
+ Infrastructure (suitable for any vendor).
+ Testsuite which covers offloading from the [6]OpenMP 4.0
Examples document.
Specific for upcoming Intel Xeon Phi products:
+ Run-time library.
+ Card emulator.
* GCC 5 includes a preliminary implementation of the OpenACC 2.0a
specification. OpenACC is intended for programming accelerator
devices such as GPUs. See [7]the OpenACC wiki page for more
information.

[8]C family

* The default setting of the -fdiagnostics-color= command-line option
is now [9]configurable when building GCC using configuration option
--with-diagnostics-color=. The possible values are: never, always,
auto and auto-if-env. The new default auto uses color only when the
standard error is a terminal. The default in GCC 4.9 was
auto-if-env, which is equivalent to auto if there is a non-empty
GCC_COLORS environment variable, and never otherwise. As in GCC
4.9, an empty GCC_COLORS variable in the environment will always
disable colors, no matter what the default is or what command-line
options are used.
* A new command-line option -Wswitch-bool has been added for the C
and C++ compilers, which warns whenever a switch statement has an
index of boolean type.
* A new command-line option -Wlogical-not-parentheses has been added
for the C and C++ compilers, which warns about "logical not" used
on the left hand side operand of a comparison.
* A new command-line option -Wsizeof-array-argument has been added
for the C and C++ compilers, which warns when the sizeof operator
is applied to a parameter that has been declared as an array in a
function definition.
* A new command-line option -Wbool-compare has been added for the C
and C++ compilers, which warns about boolean expressions compared
with an integer value different from true/false.
* Full support for Cilk Plus has been added to the GCC compiler. Cilk
Plus is an extension to the C and C++ languages to support data and
task parallelism.
* A new attribute no_reorder prevents reordering of selected symbols
against other such symbols or inline assembler. This enables to
link-time optimize the Linux kernel without having to resort to
-fno-toplevel-reorder that disables several optimizations.
* New preprocessor constructs, __has_include and __has_include_next,
to test the availability of headers have been added.
This demonstrates a way to include the header <optional> only if it
is available:

#ifdef __has_include
# if __has_include(<optional>)
# include <optional>
# define have_optional 1
# elif __has_include(<experimental/optional>)
# include <experimental/optional>
# define have_optional 1
# define experimental_optional
# else
# define have_optional 0
# endif
#endif

The header search paths for __has_include and __has_include_next
are equivalent to those of the standard directive #include and the
extension #include_next respectively.
* A new built-in function-like macro to determine the existence of an
attribute, __has_attribute, has been added. The equivalent built-in
macro __has_cpp_attribute was added to C++ to support
[10]Feature-testing recommendations for C++. The macro
__has_attribute is added to all C-like languages as an extension:

int
#ifdef __has_attribute
# if __has_attribute(__noinline__)
__attribute__((__noinline__))
# endif
#endif
foo(int x);

If an attribute exists, a nonzero constant integer is returned. For
standardized C++ attributes a date is returned, otherwise the
constant returned is 1. Both __has_attribute and
__has_cpp_attribute will add underscores to an attribute name if
necessary to resolve the name. For C++11 and onwards the attribute
may be scoped.
* A new set of built-in functions for arithmetics with overflow
checking has been added: __builtin_add_overflow,
__builtin_sub_overflow and __builtin_mul_overflow and for
compatibility with clang also other variants. These builtins have
two integral arguments (which don't need to have the same type),
the arguments are extended to infinite precision signed type, +, -
or * is performed on those, and the result is stored in an integer
variable pointed to by the last argument. If the stored value is
equal to the infinite precision result, the built-in functions
return false, otherwise true. The type of the integer variable that
will hold the result can be different from the types of the first
two arguments. The following snippet demonstrates how this can be
used in computing the size for the calloc function:

void *
calloc (size_t x, size_t y)
{
size_t sz;
if (__builtin_mul_overflow (x, y, &sz))
return NULL;
void *ret = malloc (sz);
if (ret) memset (res, 0, sz);
return ret;
}

On e.g. i?86 or x86-64 the above will result in a mul instruction
followed by a jump on overflow.
* The option -fextended-identifiers is now enabled by default for
C++, and for C99 and later C versions. Various bugs in the
implementation of extended identifiers have been fixed.

[11]C

* The default mode has been changed to -std=gnu11.
* A new command-line option -Wc90-c99-compat has been added to warn
about features not present in ISO C90, but present in ISO C99.
* A new command-line option -Wc99-c11-compat has been added to warn
about features not present in ISO C99, but present in ISO C11.
* It is possible to disable warnings about conversions between
pointers that have incompatible types via a new warning option
-Wno-incompatible-pointer-types; warnings about implicit
incompatible integer to pointer and pointer to integer conversions
via a new warning option -Wno-int-conversion; and warnings about
qualifiers on pointers being discarded via a new warning option
-Wno-discarded-qualifiers.
* To allow proper use of const qualifiers with multidimensional
arrays, GCC will not warn about incompatible pointer types anymore
for conversions between pointers to arrays with and without const
qualifier (except when using -pedantic). Instead, a new warning is
emitted only if the const qualifier is lost. This can be controlled
with a new warning option -Wno-discarded-array-qualifiers.
* The C front end now generates more precise caret diagnostics.
* The -pg command-line option now only affects the current file in an
LTO build.

[12]C++

* G++ now supports [13]C++14 variable templates.
* -Wnon-virtual-dtor doesn't warn anymore for final classes.
* Excessive template instantiation depth is now a fatal error. This
prevents excessive diagnostics that usually do not help to identify
the problem.
* G++ and libstdc++ now implement the feature-testing macros from
[14]Feature-testing recommendations for C++.
* G++ now allows typename in a template template parameter.

template<template<typename> typename X> struct D; // OK

* G++ now supports [15]C++14 aggregates with non-static data member
initializers.

struct A { int i, j = i; };
A a = { 42 }; // a.j is also 42

* G++ now supports [16]C++14 extended constexpr.

constexpr int f (int i)
{
int j = 0;
for (; i > 0; --i)
++j;
return j;
}

constexpr int i = f(42); // i is 42

* G++ now supports the [17]C++14 sized deallocation functions.

void operator delete (void *, std::size_t) noexcept;
void operator delete[] (void *, std::size_t) noexcept;

* A new One Definition Rule violation warning (controlled by -Wodr)
detects mismatches in type definitions and virtual table contents
during link-time optimization.
* New warnings -Wsuggest-final-types and -Wsuggest-final-methods help
developers to annotate programs with final specifiers (or anonymous
namespaces) to improve code generation. These warnings can be used
at compile time, but they are more useful in combination with
link-time optimization.
* G++ no longer supports [18]N3639 variable length arrays, as they
were removed from the C++14 working paper prior to ratification.
GNU VLAs are still supported, so VLA support is now the same in
C++14 mode as in C++98 and C++11 modes.
* G++ now allows passing a non-trivially-copyable class via C
varargs, which is conditionally-supported with
implementation-defined semantics in the standard. This uses the
same calling convention as a normal value parameter.
* G++ now defaults to -fabi-version=9 and -fabi-compat-version=2. So
various mangling bugs are fixed, but G++ will still emit aliases
with the old, wrong mangling where feasible. -Wabi=2 will warn
about differences between ABI version 2 and the current setting.
* G++ 5.2 fixes the alignment of std::nullptr_t. Most code is likely
to be unaffected, but -Wabi=8 will warn about a non-static data
member with type std::nullptr_t which changes position due to this
change.

[19]Runtime Library (libstdc++)

* A [20]Dual ABI is provided by the library. A new ABI is enabled by
default. The old ABI is still supported and can be used by defining
the macro _GLIBCXX_USE_CXX11_ABI to 0 before including any C++
standard library headers.
* A new implementation of std::string is enabled by default, using
the small string optimization instead of copy-on-write reference
counting.
* A new implementation of std::list is enabled by default, with an
O(1) size() function;
* [21]Full support for C++11, including the following new features:
+ std::deque and std::vector<bool> meet the allocator-aware
container requirements;
+ movable and swappable iostream classes;
+ support for std::align and std::aligned_union;
+ type traits std::is_trivially_copyable,
std::is_trivially_constructible, std::is_trivially_assignable
etc.;
+ I/O manipulators std::put_time, std::get_time, std::hexfloat
and std::defaultfloat;
+ generic locale-aware std::isblank;
+ locale facets for Unicode conversion;
+ atomic operations for std::shared_ptr;
+ std::notify_all_at_thread_exit() and functions for making
futures ready at thread exit.
* Support for the C++11 hexfloat manipulator changes how the num_put
facet formats floating point types when
ios_base::fixed|ios_base::scientific is set in a stream's fmtflags.
This change affects all language modes, even though the C++98
standard gave no special meaning to that combination of flags. To
prevent the use of hexadecimal notation for floating point types
use str.unsetf(std::ios_base::floatfield) to clear the relevant
bits in str.flags().
* [22]Full experimental support for C++14, including the following
new features:
+ std::is_final type trait;
+ heterogeneous comparison lookup in associative containers.
+ global functions cbegin, cend, rbegin, rend, crbegin, and
crend for range access to containers, arrays and initializer
lists.
* [23]Improved experimental support for the Library Fundamentals TS,
including:
+ class std::experimental::any;
+ function template std::experimental::apply;
+ function template std::experimental::sample;
+ function template std::experimental::search and related
searcher types;
+ variable templates for type traits;
+ function template std::experimental::not_fn.
* New random number distributions logistic_distribution and
uniform_on_sphere_distribution as extensions.
* [24]GDB Xmethods for containers and std::unique_ptr.

[25]Fortran

* Compatibility notice:
+ The version of the module files (.mod) has been incremented.
+ For free-form source files [26]-Werror=line-truncation is now
enabled by default. Note that comments exceeding the line
length are not diagnosed. (For fixed-form source code, the
same warning is available but turned off by default, such that
excess characters are ignored. -ffree-line-length-n and
-ffixed-line-length-n can be used to modify the default line
lengths of 132 and 72 columns, respectively.)
+ The -Wtabs option is now more sensible: with -Wtabs the
compiler warns if it encounters tabs and with -Wno-tabs this
warning is turned off. Before, -Wno-tabs warned and -Wtabs
disabled the warning. As before, this warning is also enabled
by -Wall, -pedantic and the f95, f2003, f2008 and f2008ts
options of -std=.
* Incomplete support for colorizing diagnostics emitted by gfortran
has been added. The option [27]-fdiagnostics-color controls when
color is used in diagnostics. The default value of this option can
be [28]configured when building GCC. The GCC_COLORS environment
variable can be used to customize the colors or disable coloring
completely. Sample diagnostics output:
$ gfortran -fdiagnostics-color=always -Wuse-without-only test.f90
test.f90:6:1:

0 continue
1
Error: Zero is not a valid statement label at (1)
test.f90:9:6:

USE foo
1
Warning: USE statement at (1) has no ONLY qualifier [-Wuse-without-only]

* The -Wuse-without-only option has been added to warn when a USE
statement has no ONLY qualifier and thus implicitly imports all
public entities of the used module.
* Formatted READ and WRITE statements now work correctly in
locale-aware programs. For more information and potential caveats,
see [29]Section 5.3 Thread-safety of the runtime library in the
manual.
* [30]Fortran 2003:
+ The intrinsic IEEE modules (IEEE_FEATURES, IEEE_EXCEPTIONS and
IEEE_ARITHMETIC) are now supported.
* [31]Fortran 2008:
+ [32]Coarrays: Full experimental support of Fortran 2008's
coarrays with -fcoarray=lib except for allocatable/pointer
components of derived-type coarrays. GCC currently only ships
with a single-image library (libcaf_single), but multi-image
support based on MPI and GASNet is provided by the libraries
of the [33]OpenCoarrays project.
* TS18508 Additional Parallel Features in Fortran:
+ Support for the collective intrinsic subroutines CO_MAX,
CO_MIN, CO_SUM, CO_BROADCAST and CO_REDUCE has been added,
including -fcoarray=lib support.
+ Support for the new atomic intrinsics has been added,
including -fcoarray=lib support.
* Fortran 2015:
+ Support for IMPLICIT NONE (external, type).
+ ERROR STOP is now permitted in pure procedures.

[34]Go

* GCC 5 provides a complete implementation of the Go 1.4.2 release.
* Building GCC 5 with Go enabled will install two new programs:
[35]go and [36]gofmt.

[37]libgccjit

New in GCC 5 is the ability to build GCC as a shared library for
embedding in other processes (such as interpreters), suitable for
Just-In-Time compilation to machine code.

The shared library has a [38]C API and a [39]C++ wrapper API providing
some "syntactic sugar". There are also bindings available from 3rd
parties for [40]Python and for [41]D.

For example, this library can be used by interpreters for [42]compiling
functions from bytecode to machine code.

The library can also be used for ahead-of-time compilation, enabling
GCC to be plugged into a pre-existing front end. An example of using
this to build a compiler for an esoteric language we'll refer to as
"brainf" can be seen [43]here.

libgccjit is licensed under the GPLv3 (or at your option, any later
version)

It should be regarded as experimental at this time.

[44]New Targets and Target Specific Improvements

[45]Reporting stack usage

* The BFIN, FT32, H8300, IQ2000 and M32C targets now support the
-fstack-usage option.

[46]AArch64

* Code generation for the ARM Cortex-A57 processor has been improved.
A more accurate instruction scheduling model for the processor is
now used, and a number of compiler tuning parameters have been set
to offer increased performance when compiling with -mcpu=cortex-a57
or -mtune=cortex-a57.
* A workaround for the ARM Cortex-A53 erratum 835769 has been added
and can be enabled by giving the -mfix-cortex-a53-835769 option.
Alternatively it can be enabled by default by configuring GCC with
the --enable-fix-cortex-a53-835769 option.
* The optional cryptographic extensions to the ARMv8-A architecture
are no longer enabled by default when specifying the
-mcpu=cortex-a53, -mcpu=cortex-a57 or -mcpu=cortex-a57.cortex-a53
options. To enable these extensions add +crypto to the value of
-mcpu or -march e.g. -mcpu=cortex-a53+crypto.
* Support has been added for the following processors (GCC
identifiers in parentheses): ARM Cortex-A72 (cortex-a72) and
initial support for its big.LITTLE combination with the ARM
Cortex-A53 (cortex-a72.cortex-a53), Cavium ThunderX (thunderx),
Applied Micro X-Gene 1 (xgene1), and Samsung Exynos M1 (exynos-m1).
The GCC identifiers can be used as arguments to the -mcpu or -mtune
options, for example: -mcpu=xgene1 or -mtune=cortex-a72.cortex-a53.
Using -mcpu=cortex-a72 requires a version of GNU binutils that has
support for the Cortex-A72.
* The transitional options -mlra and -mno-lra have been removed. The
AArch64 back end now uses the local register allocator (LRA) only.

[47]ARM

* Thumb-1 assembly code is now generated in unified syntax. The new
option -masm-syntax-unified specifies whether inline assembly code
is using unified syntax. By default the option is off which means
non-unified syntax is used. However this is subject to change in
future releases. Eventually the non-unified syntax will be
deprecated.
* It is now a configure-time error to use the --with-cpu configure
option with either of --with-tune or --with-arch.
* Code generation for the ARM Cortex-A57 processor has been improved.
A more accurate instruction scheduling model for the processor is
now used, and a number of compiler tuning parameters have been set
to offer increased performance when compiling with -mcpu=cortex-a57
or -mtune=cortex-a57.
* Support has been added for the following processors (GCC
identifiers in parentheses): ARM Cortex-A17 (cortex-a17) and
initial support for its big.LITTLE combination with the ARM
Cortex-A7 (cortex-a17.cortex-a7), ARM Cortex-A72 (cortex-a72) and
initial support for its big.LITTLE combination with the ARM
Cortex-A53 (cortex-a72.cortex-a53), ARM Cortex-M7 (cortex-m7),
Applied Micro X-Gene 1 (xgene1), and Samsung Exynos M1 (exynos-m1).
The GCC identifiers can be used as arguments to the -mcpu or -mtune
options, for example: -mcpu=xgene1 or -mtune=cortex-a72.cortex-a53.
Using -mcpu=cortex-a72 requires a version of GNU binutils that has
support for the Cortex-A72.
* The deprecated option -mwords-little-endian has been removed.
* The options -mapcs, -mapcs-frame, -mtpcs-frame and
-mtpcs-leaf-frame which are only applicable to the old ABI have
been deprecated.
* The transitional options -mlra and -mno-lra have been removed. The
ARM back end now uses the local register allocator (LRA) only.

[48]AVR

* Support has been added for the devices ATtiny4/5/9/10/20/40. This
requires Binutils 2.25 or newer.
* The port uses a new scheme to describe supported devices: For each
supported device, the compiler provides a device-specific [49]spec
file. If the compiler is used together with AVR-LibC, this requires
at least GCC 5.2 and a version of AVR-LibC which implements
[50]feature #44574.
As a consequence, the compiler no more supports individual devices
like ATmega8. Specifying, say, -mmcu=atmega8 triggers the usage of
the device-specific [51]spec file specs-atmega8 which is part of
the installation and describes options for the sub-processes like
compiler proper, assembler and linker. You can add support for a
new device -mmcu=mydevice as follows:
1. In an empty directory /someplace, create a new directory
device-specs.
2. Copy a device spec file from the installed device-specs
folder, follow the comments in that file and then save it as
/someplace/device-specs/specs-mydevice.
3. Add -B /someplace -mmcu=mydevice to the compiler's
command-line options. Notice that /someplace must specify an
absolute path and that mydevice must not start with "avr".
4. Provided you have a device-specific library libmydevice.a
available, you can put it at /someplace, dito for a
device-specific startup file crtmydevice.o.
The contents of the device spec files depend on the compiler's
configuration, in particular on --with-avrlibc=no and whether or
not it is configured for RTEMS.
* A new command-line option -nodevicelib has been added. It prevents
the compiler from linking against AVR-LibC's device-specific
library libdevice.a.
* The following three command-line options have been added:

-mrmw
Set if the device supports the read-modify-write
instructions LAC, LAS, LAT and XCH.

-mn-flash=size
Specify the flash size of the device in units of 64 KiB,
rounded up to the next integer as needed. This option
affects the availability of the [52]AVR address-spaces.

-mskip-bug
Set if the device is affected by the respective silicon
bug.

These options are used internally in order to communicate between
the compiler and the device-spces file. They are set in the
device-specs file as needed. Don't set them by hand.

[53]IA-32/x86-64

* New ISA extensions support AVX-512{BW,DQ,VL,IFMA,VBMI} of Intel's
CPU codenamed Skylake Server was added to GCC. That includes inline
assembly support, new intrinsics, and basic autovectorization.
These new AVX-512 extensions are available via the following GCC
switches: AVX-512 Vector Length EVEX feature: -mavx512vl, AVX-512
Byte and Word instructions: -mavx512bw, AVX-512 Dword and Qword
instructions: -mavx512dq, AVX-512 FMA-52 instructions: -mavx512ifma
and for AVX-512 Vector Bit Manipulation Instructions: -mavx512vbmi.
* New ISA extensions support Intel MPX was added to GCC. This new
extension is available via the -mmpx compiler switch. Intel MPX is
a set of processor features which, with compiler, run-time library
and OS support, brings increased robustness to software by run-time
checking pointer references against their bounds. In GCC Intel MPX
is supported by Pointer Bounds Checker and libmpx run-time
libraries.
* The new -mrecord-mcount option for -pg generates a Linux kernel
style table of pointers to mcount or __fentry__ calls at the
beginning of functions. The new -mnop-mcount option in addition
also generates nops in place of the __fentry__ or mcount call, so
that a call per function can be later patched in. This can be used
for low overhead tracing or hot code patching.
* The new -malign-data option controls how GCC aligns variables.
-malign-data=compat uses increased alignment compatible with GCC
4.8 and earlier, -malign-data=abi uses alignment as specified by
the psABI, and -malign-data=cacheline uses increased alignment to
match the cache line size. -malign-data=compat is the default.
* The new -mskip-rax-setup option skips setting up the RAX register
when SSE is disabled and there are no variable arguments passed in
vector registers. This can be used to optimize the Linux kernel.

[54]MIPS

* MIPS Releases 3 and 5 are now directly supported. Use the
command-line options -mips32r3, -mips64r3, -mips32r5 and -mips64r5
to enable code-generation for these processors.
* The Imagination P5600 processor is now supported using the
-march=p5600 command-line option.
* The Cavium Octeon3 processor is now supported using the
-march=octeon3 command-line option.
* MIPS Release 6 is now supported using the -mips32r6 and -mips64r6
command-line options.
* The o32 ABI has been modified and extended. The o32 64-bit
floating-point register support is now obsolete and has been
removed. It has been replaced by three ABI extensions FPXX, FP64A,
and FP64. The meaning of the -mfp64 command-line option has
changed. It is now used to enable the FP64A and FP64 ABI
extensions.
+ The FPXX extension requires that code generated to access
double-precision values use even-numbered registers. Code that
adheres to this extension is link-compatible with all other
o32 double-precision ABI variants and will execute correctly
in all hardware FPU modes. The command-line options -mabi=32
-mfpxx can be used to enable this extension. MIPS II is the
minimum processor required.
+ The o32 FP64A extension requires that floating-point registers
be 64-bit and odd-numbered single-precision registers are not
allowed. Code that adheres to the o32 FP64A variant is
link-compatible with all other o32 double-precision ABI
variants. The command-line options -mabi=32 -mfp64
-mno-odd-spreg can be used to enable this extension. MIPS32R2
is the minimum processor required.
+ The o32 FP64 extension also requires that floating-point
registers be 64-bit, but permits the use of single-precision
registers. Code that adheres to the o32 FP64 variant is
link-compatible with o32 FPXX and o32 FP64A variants only,
i.e. it is not compatible with the original o32
double-precision ABI. The command-line options -mabi=32 -mfp64
-modd-spreg can be used to enable this extension. MIPS32R2 is
the minimum processor required.
The new ABI variants can be enabled by default using the configure
time options --with-fp-32=[32|xx|64] and --with(out)-odd-sp-reg-32.
It is strongly recommended that all vendors begin to set o32 FPXX
as the default ABI. This will be required to run the generated code
on MIPSR5 cores in conjunction with future MIPS SIMD (MSA) code and
MIPSR6 cores.
* GCC will now pass all floating-point options to the assembler if
GNU binutils 2.25 is used. As a result, any inline assembly code
that uses hard-float instructions should be amended to include a
.set directive to override the global assembler options when
compiling for soft-float targets.

[55]NDS32

* The variadic function ABI implementation is now compatible with
past Andes toolchains where the caller uses registers to pass
arguments and the callee is in charge of pushing them on stack.
* The options -mforce-fp-as-gp, -mforbid-fp-as-gp, and -mex9 have
been removed since they are not yet available in the nds32 port of
GNU binutils.
* A new option -mcmodel=[small|medium|large] supports varied code
models on code generation. The -mgp-direct option became
meaningless and can be discarded.

[56]RX

* A new command line option -mno-allow-string-insns can be used to
disable the generation of the SCMPU, SMOVU, SMOVB, SMOVF, SUNTIL,
SWHILE and RMPA instructions. An erratum released by Renesas shows
that it is unsafe to use these instructions on addresses within the
I/O space of the processor. The new option can be used when the
programmer is concerned that the I/O space might be accessed. The
default is still to enable these instructions.

[57]SH

* The compiler will now pass the appropriate --isa= option to the
assembler.
* The default handling for the GBR has been changed from call
clobbered to call preserved. The old behavior can be reinstated by
specifying the option -fcall-used-gbr.
* Support for the SH4A fpchg instruction has been added which will be
utilized when switching between single and double precision FPU
modes.
* The compiler no longer uses the __fpscr_values array for switching
between single and double FPU precision modes on non-SH4A targets.
Instead mode switching will now be performed by storing, modifying
and reloading the FPSCR, so that other FPSCR bits are preserved
across mode switches. The __fpscr_values array that is defined in
libgcc is still present for backwards compatibility, but it will
not be referenced by compiler generated code anymore.
* New builtin functions __builtin_sh_get_fpscr and
__builtin_sh_set_fpscr have been added. The __builtin_sh_set_fpscr
function will mask the specified bits in such a way that the SZ, PR
and FR mode bits will be preserved, while changing the other bits.
These new functions do not reference the __fpscr_values array. The
old functions __set_fpscr and __get_fpscr in libgcc which access
the __fpscr_values array are still present for backwards
compatibility, but their usage is highly discouraged.
* Some improvements to code generated for __atomic built-in
functions.
* When compiling for SH2E the compiler will no longer force the usage
of delay slots for conditional branch instructions bt and bf. The
old behavior can be reinstated (e.g. to work around a hardware bug
in the original SH7055) by specifying the new option
-mcbranch-force-delay-slot.

[58]Operating Systems

[59]AIX

* GCC now supports stabs debugging continuation lines to allow long
stabs debug information without overflow that generates AIX linker
errors.

[60]DragonFly BSD

* GCC now supports the DragonFly BSD operating system.

[61]FreeBSD

* GCC now supports the FreeBSD operating system for the arm port
through the arm*-*-freebsd* target triplets.

[62]VxWorks MILS

* GCC now supports the MILS (Multiple Independent Levels of Security)
variant of WindRiver's VxWorks operating system for PowerPC
targets.

Other significant improvements

* The gcc-ar, gcc-nm, gcc-ranlib wrappers now understand a -B option
to set the compiler to use.

* When the new command-line option -freport-bug is used, GCC
automatically generates a developer-friendly reproducer whenever an
internal compiler error is encountered.

[63]GCC 5.2

This is the [64]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 5.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Target Specific Changes

IA-32/x86-64

* Support for new AMD instructions monitorx and mwaitx has been
added. This includes new intrinsic and built-in support. It is
enabled through option -mmwaitx. The instructions monitorx and
mwaitx implement the same functionality as the old monitor and
mwait instructions. In addition, mwaitx adds a configurable timer.
The timer value is received as third argument and stored in
register %ebx.

S/390, System z, IBM z Systems

* Support for the IBM z13 processor has been added. When using the
-march=z13 option, the compiler will generate code making use of
the new instructions and registers introduced with the vector
extension facility. The -mtune=z13 option enables z13 specific
instruction scheduling without making use of new instructions.
Compiling code with -march=z13 reduces the default alignment of
vector types bigger than 8 bytes to 8. This is an ABI change and
care must be taken when linking modules compiled with different
arch levels which interchange variables containing vector type
values. For newly compiled code the GNU linker will emit a warning.
* The -mzvector option enables a C/C++ language extension. This
extension provides a new keyword vector which can be used to define
vector type variables. (Note: This is not available when enforcing
strict standard compliance e.g. with -std=c99. Either enable GNU
extensions with e.g. -std=gnu99 or use __vector instead of vector.)
Additionally a set of overloaded builtins is provided which is
partially compatible to the PowerPC Altivec builtins. In order to
make use of these builtins the vecintrin.h header file needs to be
included.

[65]GCC 5.3

This is the [66]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 5.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Target Specific Changes

IA-32/x86-64

* GCC now supports the Intel CPU named Skylake with AVX-512
extensions through -march=skylake-avx512. The switch enables the
following ISA extensions: AVX-512F, AVX512VL, AVX-512CD, AVX-512BW,
AVX-512DQ.

S/390, System z, IBM z Systems

* With this version of GCC IBM z Systems support has been added to
the GO runtime environment. GCC 5.3 has proven to be able to
compile larger GO applications on IBM z Systems.

[67]GCC 5.4

This is the [68]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 5.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[69]GCC 5.5

This is the [70]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 5.5 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Target Specific Changes

IA-32/x86-64

* Support for the [71]deprecated pcommit instruction has been
removed.

For questions related to the use of GCC, please consult these web
pages and the [72]GCC manuals. If that fails, the
[73][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [74][email protected]. All of [75]our lists have public
archives.

Copyright (C) [76]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [77]maintained by the GCC team. Last modified
2025-02-28.

References

1. https://gcc.gnu.org/gcc-5/changes.html#libstdcxx
2. https://gcc.gnu.org/gcc-5/changes.html#general
3. https://gcc.gnu.org/wiki/Intel%20MPX%20support%20in%20the%20GCC%20compiler
4. https://gcc.gnu.org/gcc-5/changes.html#languages
5. https://www.openmp.org/wp-content/uploads/OpenMP4.0.0.pdf
6. https://www.openmp.org/wp-content/uploads/OpenMP4.0.0.Examples.pdf
7. https://gcc.gnu.org/wiki/OpenACC
8. https://gcc.gnu.org/gcc-5/changes.html#c-family
9. https://gcc.gnu.org/install/configure.html
10. https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations
11. https://gcc.gnu.org/gcc-5/changes.html#c
12. https://gcc.gnu.org/gcc-5/changes.html#cxx
13. https://gcc.gnu.org/projects/cxx1y.html
14. https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations
15. https://gcc.gnu.org/projects/cxx1y.html
16. https://gcc.gnu.org/projects/cxx1y.html
17. https://gcc.gnu.org/projects/cxx1y.html
18. https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3639.html
19. https://gcc.gnu.org/gcc-5/changes.html#libstdcxx
20. https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html
21. https://gcc.gnu.org/onlinedocs/gcc-5.1.0/libstdc++/manual/manual/status.html#status.iso.2011
22. https://gcc.gnu.org/onlinedocs/gcc-5.1.0/libstdc++/manual/manual/status.html#status.iso.2014
23. https://gcc.gnu.org/onlinedocs/gcc-5.1.0/libstdc++/manual/manual/status.html#status.iso.2014
24. https://sourceware.org/gdb/current/onlinedocs/gdb#Xmethods-In-Python
25. https://gcc.gnu.org/gcc-5/changes.html#fortran
26. https://gcc.gnu.org/onlinedocs/gcc-5.1.0/gfortran/Error-and-Warning-Options.html
27. https://gcc.gnu.org/onlinedocs/gcc-5.1.0/gcc/Language-Independent-Options.html
28. https://gcc.gnu.org/install/configure.html
29. https://gcc.gnu.org/onlinedocs/gcc-5.1.0/gfortran/Thread-safety-of-the-runtime-library.html
30. https://gcc.gnu.org/wiki/Fortran2003Status
31. https://gcc.gnu.org/wiki/Fortran2008Status
32. https://gcc.gnu.org/wiki/Coarray
33. http://www.opencoarrays.org/
34. https://gcc.gnu.org/gcc-5/changes.html#go
35. https://pkg.go.dev/cmd/go
36. https://pkg.go.dev/cmd/gofmt
37. https://gcc.gnu.org/gcc-5/changes.html#jit
38. https://gcc.gnu.org/onlinedocs/gcc-5.1.0/jit/intro/index.html
39. https://gcc.gnu.org/onlinedocs/gcc-5.1.0/jit/cp/index.html
40. https://github.com/davidmalcolm/pygccjit
41. https://github.com/ibuclaw/gccjitd
42. https://gcc.gnu.org/onlinedocs/gcc-5.1.0/jit/intro/tutorial04.html
43. https://gcc.gnu.org/onlinedocs/gcc-5.1.0/jit/intro/tutorial05.html
44. https://gcc.gnu.org/gcc-5/changes.html#targets
45. https://gcc.gnu.org/gcc-5/changes.html#stack-usage
46. https://gcc.gnu.org/gcc-5/changes.html#aarch64
47. https://gcc.gnu.org/gcc-5/changes.html#arm
48. https://gcc.gnu.org/gcc-5/changes.html#avr
49. https://gcc.gnu.org/onlinedocs/gcc/Spec-Files.html
50. https://savannah.nongnu.org/bugs/?44574
51. https://gcc.gnu.org/onlinedocs/gcc/Spec-Files.html
52. https://gcc.gnu.org/onlinedocs/gcc/Named-Address-Spaces.html
53. https://gcc.gnu.org/gcc-5/changes.html#x86
54. https://gcc.gnu.org/gcc-5/changes.html#mips
55. https://gcc.gnu.org/gcc-5/changes.html#nds32
56. https://gcc.gnu.org/gcc-5/changes.html#rx
57. https://gcc.gnu.org/gcc-5/changes.html#sh
58. https://gcc.gnu.org/gcc-5/changes.html#os
59. https://gcc.gnu.org/gcc-5/changes.html#aix
60. https://gcc.gnu.org/gcc-5/changes.html#dragonfly
61. https://gcc.gnu.org/gcc-5/changes.html#freebsd
62. https://gcc.gnu.org/gcc-5/changes.html#vxmils
63. https://gcc.gnu.org/gcc-5/changes.html#GCC5.2
64. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=5.2
65. https://gcc.gnu.org/gcc-5/changes.html#GCC5.3
66. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=5.3
67. https://gcc.gnu.org/gcc-5/changes.html#GCC5.4
68. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=5.4
69. https://gcc.gnu.org/gcc-5/changes.html#GCC5.5
70. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=5.5
71. https://www.intel.com/content/www/us/en/developer/articles/technical/deprecate-pcommit-instruction.html
72. https://gcc.gnu.org/onlinedocs/
73. mailto:[email protected]
74. mailto:[email protected]
75. https://gcc.gnu.org/lists.html
76. https://www.fsf.org/
77. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.9/index.html

GCC 4.9 Release Series

(This release series is no longer supported.)

Aug 3, 2016

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 4.9.4.

This release is a bug-fix release, containing fixes for regressions in
GCC 4.9.3 relative to previous releases of GCC.

Release History

GCC 4.9.4
Aug 3, 2016 ([2]changes, [3]documentation)

GCC 4.9.3
June 26, 2015 ([4]changes, [5]documentation)

GCC 4.9.2
October 30, 2014 ([6]changes, [7]documentation)

GCC 4.9.1
July 16, 2014 ([8]changes, [9]documentation)

GCC 4.9.0
April 22, 2014 ([10]changes, [11]documentation)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [12]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [13]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [14]GCC
project web site or contact the [15]GCC development mailing list.

To obtain GCC please use [16]our mirror sites or [17]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [18]GCC manuals. If that fails, the
[19][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [20][email protected]. All of [21]our lists have public
archives.

Copyright (C) [22]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [23]maintained by the GCC team. Last modified
2024-05-30.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-4.9/changes.html
3. https://gcc.gnu.org/onlinedocs/4.9.4/
4. https://gcc.gnu.org/gcc-4.9/changes.html
5. https://gcc.gnu.org/onlinedocs/4.9.3/
6. https://gcc.gnu.org/gcc-4.9/changes.html
7. https://gcc.gnu.org/onlinedocs/4.9.2/
8. https://gcc.gnu.org/gcc-4.9/changes.html
9. https://gcc.gnu.org/onlinedocs/4.9.1/
10. https://gcc.gnu.org/gcc-4.9/changes.html
11. https://gcc.gnu.org/onlinedocs/4.9.0/
12. https://gcc.gnu.org/gcc-4.9/buildstat.html
13. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
14. https://gcc.gnu.org/index.html
15. mailto:[email protected]
16. https://gcc.gnu.org/mirrors.html
17. https://gcc.gnu.org/git.html
18. https://gcc.gnu.org/onlinedocs/
19. mailto:[email protected]
20. mailto:[email protected]
21. https://gcc.gnu.org/lists.html
22. https://www.fsf.org/
23. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.9/changes.html

GCC 4.9 Release Series
Changes, New Features, and Fixes

Caveats

* The mudflap run time checker has been removed. The mudflap options
remain, but do nothing.
* Support for a number of older systems and recently unmaintained or
untested target ports of GCC has been declared obsolete in GCC 4.9.
Unless there is activity to revive them, the next release of GCC
will have their sources permanently removed.
The following ports for individual systems on particular
architectures have been obsoleted:
+ Solaris 9 (*-*-solaris2.9). Details can be found in the
[1]announcement.
* On AArch64, the singleton vector types int64x1_t, uint64x1_t and
float64x1_t exported by arm_neon.h are defined to be the same as
their base types. This results in incorrect application of
parameter passing rules to arguments of types int64x1_t and
uint64x1_t, with respect to the AAPCS64 ABI specification. In
addition, names of C++ functions with parameters of these types
(including float64x1_t) are not mangled correctly. The current
typedef declarations also unintentionally allow implicit casting
between singleton vector types and their base types. These issues
will be resolved in a near future release. See [2]PR60825 for more
information.

More information on porting to GCC 4.9 from previous versions of GCC
can be found in the [3]porting guide for this release.

General Optimizer Improvements

* AddressSanitizer, a fast memory error detector, is now available on
ARM.
* UndefinedBehaviorSanitizer (ubsan), a fast undefined behavior
detector, has been added and can be enabled via
-fsanitize=undefined. Various computations will be instrumented to
detect undefined behavior at runtime. UndefinedBehaviorSanitizer is
currently available for the C and C++ languages.
* Link-time optimization (LTO) improvements:
+ Type merging was rewritten. The new implementation is
significantly faster and uses less memory.
+ Better partitioning algorithm resulting in less streaming
during link time.
+ Early removal of virtual methods reduces the size of object
files and improves link-time memory usage and compile time.
+ Function bodies are now loaded on-demand and released early
improving overall memory usage at link time.
+ C++ hidden keyed methods can now be optimized out.
+ When using a linker plugin, compiling with the -flto option
now generates slim object files (.o) which only contain
intermediate language representation for LTO. Use
-ffat-lto-objects to create files which contain additionally
the object code. To generate static libraries suitable for LTO
processing, use gcc-ar and gcc-ranlib; to list symbols from a
slim object file use gcc-nm. (This requires that ar, ranlib
and nm have been compiled with plugin support.)
Memory usage building Firefox with debug enabled was reduced from
15GB to 3.5GB; link time from 1700 seconds to 350 seconds.
* Inter-procedural optimization improvements:
+ New type inheritance analysis module improving
devirtualization. Devirtualization now takes into account
anonymous name-spaces and the C++11 final keyword.
+ New speculative devirtualization pass (controlled by
-fdevirtualize-speculatively.
+ Calls that were speculatively made direct are turned back to
indirect where direct call is not cheaper.
+ Local aliases are introduced for symbols that are known to be
semantically equivalent across shared libraries improving
dynamic linking times.
* Feedback directed optimization improvements:
+ Profiling of programs using C++ inline functions is now more
reliable.
+ New time profiling determines typical order in which functions
are executed.
+ A new function reordering pass (controlled by
-freorder-functions) significantly reduces startup time of
large applications. Until binutils support is completed, it is
effective only with link-time optimization.
+ Feedback driven indirect call removal and devirtualization now
handle cross-module calls when link-time optimization is
enabled.

[4]New Languages and Language specific improvements

* Version 4.0 of the [5]OpenMP specification is now supported in the
C and C++ compilers and starting with the 4.9.1 release also in the
Fortran compiler. The new -fopenmp-simd option can be used to
enable OpenMP's SIMD directives while ignoring other OpenMP
directives. The new [6]-fsimd-cost-model= option permits to tune
the vectorization cost model for loops annotated with OpenMP and
Cilk Plus simd directives. -Wopenmp-simd warns when the current
cost model overrides simd directives set by the user.
* The -Wdate-time option has been added for the C, C++ and Fortran
compilers, which warns when the __DATE__, __TIME__ or __TIMESTAMP__
macros are used. Those macros might prevent bit-wise-identical
reproducible compilations.

[7]Ada

* GNAT switched to Ada 2012 instead of Ada 2005 by default.

[8]C family

* Support for colorizing diagnostics emitted by GCC has been added.
The [9]-fdiagnostics-color=auto will enable it when outputting to
terminals, -fdiagnostics-color=always unconditionally. The
GCC_COLORS environment variable can be used to customize the colors
or disable coloring. If GCC_COLORS variable is present in the
environment, the default is -fdiagnostics-color=auto, otherwise
-fdiagnostics-color=never.
Sample diagnostics output:
$ g++ -fdiagnostics-color=always -S -Wall test.C
test.C: In function `int foo()':
test.C:1:14: warning: no return statement in function returning non-void [-W
return-type]
int foo () { }
^
test.C:2:46: error: template instantiation depth exceeds maximum of 900 (use
-ftemplate-depth= to increase the maximum) instantiating `struct X<100>'
template <int N> struct X { static const int value = X<N-1>::value; }; temp
late struct X<1000>;
^
test.C:2:46: recursively required from `const int X<999>::value'
test.C:2:46: required from `const int X<1000>::value'
test.C:2:88: required from here

test.C:2:46: error: incomplete type `X<100>' used in nested name specifier

* With the new [10]#pragma GCC ivdep, the user can assert that there
are no loop-carried dependencies which would prevent concurrent
execution of consecutive iterations using SIMD (single instruction
multiple data) instructions.
* Support for Cilk Plus has been added and can be enabled with the
-fcilkplus option. Cilk Plus is an extension to the C and C++
languages to support data and task parallelism. The present
implementation follows ABI version 1.2; all features but _Cilk_for
have been implemented.

[11]C

* ISO C11 atomics (the _Atomic type specifier and qualifier and the
<stdatomic.h> header) are now supported.
* ISO C11 generic selections (_Generic keyword) are now supported.
* ISO C11 thread-local storage (_Thread_local, similar to GNU C
__thread) is now supported.
* ISO C11 support is now at a similar level of completeness to ISO
C99 support: substantially complete modulo bugs, extended
identifiers (supported except for corner cases when
-fextended-identifiers is used), floating-point issues (mainly but
not entirely relating to optional C99 features from Annexes F and
G) and the optional Annexes K (Bounds-checking interfaces) and L
(Analyzability).
* A new C extension __auto_type provides a subset of the
functionality of C++11 auto in GNU C.

[12]C++

* The G++ implementation of [13]C++1y return type deduction for
normal functions has been updated to conform to [14]N3638, the
proposal accepted into the working paper. Most notably, it adds
decltype(auto) for getting decltype semantics rather than the
template argument deduction semantics of plain auto:

int& f();
auto i1 = f(); // int
decltype(auto) i2 = f(); // int&

* G++ supports [15]C++1y lambda capture initializers:

[x = 42]{ ... };

Actually, they have been accepted since GCC 4.5, but now the
compiler doesn't warn about them with -std=c++1y, and supports
parenthesized and brace-enclosed initializers as well.
* G++ supports [16]C++1y variable length arrays. G++ has supported
GNU/C99-style VLAs for a long time, but now additionally supports
initializers and lambda capture by reference. In C++1y mode G++
will complain about VLA uses that are not permitted by the draft
standard, such as forming a pointer to VLA type or applying sizeof
to a VLA variable. Note that it now appears that VLAs will not be
part of C++14, but will be part of a separate document and then
perhaps C++17.

void f(int n) {
int a[n] = { 1, 2, 3 }; // throws std::bad_array_length if n < 3
[&a]{ for (int i : a) { cout << i << endl; } }();
&a; // error, taking address of VLA
}

* G++ supports the [17]C++1y [[deprecated]] attribute modulo bugs in
the underlying [[gnu::deprecated]] attribute. Classes and functions
can be marked deprecated and a diagnostic message added:

class A;
int bar(int n);
#if __cplusplus > 201103
class [[deprecated("A is deprecated in C++14; Use B instead")]] A;
[[deprecated("bar is unsafe; use foo() instead")]]
int bar(int n);

int foo(int n);
class B;
#endif
A aa; // warning: 'A' is deprecated : A is deprecated in C++14; Use B instead
int j = bar(2); // warning: 'int bar(int)' is deprecated : bar is unsafe; use fo
o() instead

* G++ supports [18]C++1y digit separators. Long numeric literals can
be subdivided with a single quote ' to enhance readability:

int i = 1048576;
int j = 1'048'576;
int k = 0x10'0000;
int m = 0'004'000'000;
int n = 0b0001'0000'0000'0000'0000'0000;

double x = 1.602'176'565e-19;
double y = 1.602'176'565e-1'9;

* G++ supports [19]C++1y generic (polymorphic) lambdas.

// a functional object that will increment any type
auto incr = [](auto x) { return x++; };

* As a GNU extension, G++ supports explicit template parameter syntax
for generic lambdas. This can be combined in the expected way with
the standard auto syntax.

// a functional object that will add two like-type objects
auto add = [] <typename T> (T a, T b) { return a + b; };

* G++ supports unconstrained generic functions as specified by �4.1.2
and �5.1.1 of [20]N3889: Concepts Lite Specification. Briefly, auto
may be used as a type-specifier in a parameter declaration of any
function declarator in order to introduce an implicit function
template parameter, akin to generic lambdas.

// the following two function declarations are equivalent
auto incr(auto x) { return x++; }
template <typename T>
auto incr(T x) { return x++; }

Runtime Library (libstdc++)

* [21]Improved support for C++11, including:
+ support for <regex>;
+ The associative containers in <map> and <set> and the
unordered associative containers in <unordered_map> and
<unordered_set> meet the allocator-aware container
requirements;
* [22]Improved experimental support for the upcoming ISO C++
standard, C++14, including:
+ fixing constexpr member functions without const;
+ implementation of the std::exchange() utility function;
+ addressing tuples by type;
+ implemention of std::make_unique;
+ implemention of std::shared_lock;
+ making std::result_of SFINAE-friendly;
+ adding operator() to std::integral_constant;
+ adding user-defined literals for standard library types
std::basic_string, std::chrono::duration, and std::complex;
+ adding two range overloads to non-modifying sequence oprations
std::equal and std::mismatch;
+ adding IO manipulators for quoted strings;
+ adding constexpr members to <utility>, <complex>, <chrono>,
and some containers;
+ adding compile-time std::integer_sequence;
+ adding cleaner transformation traits;
+ making <functional>s operator functors easier to use and more
generic;
* An implementation of std::experimental::optional.
* An implementation of std::experimental::string_view.
* The non-standard function std::copy_exception has been deprecated
and will be removed in a future version. std::make_exception_ptr
should be used instead.

[23]Fortran

* Compatibility notice:
+ Module files: The version of the module files (.mod) has been
incremented; additionally, module files are now compressed.
Fortran MODULEs compiled by earlier GCC versions have to be
recompiled, when they are USEd by files compiled with GCC 4.9.
GCC 4.9 is not able to read .mod files of earlier GCC
versions; attempting to do so gives an error message. Note:
The ABI of the produced assembler data itself has not changed:
object files and libraries are fully compatible with older
versions (except as stated below).
+ ABI changes:
o The [24]argument passing ABI has changed for scalar dummy
arguments of type INTEGER, REAL, COMPLEX and LOGICAL,
which have both the VALUE and the OPTIONAL attributes.
o To support finalization the virtual table associated with
polymorphic variables has changed. Code containing CLASS
should be recompiled, including all files which define
derived types involved in the type definition used by
polymorphic variables. (Note: Due to the incremented
module version, trying to mix old code with new code will
usually give an error message.)
+ GNU Fortran no longer deallocates allocatable variables or
allocatable components of variables declared in the main
program. Since Fortran 2008, the standard explicitly states
that variables declared in the Fortran main program
automatically have the SAVE attribute.
+ When opening files, the close-on-exec flag is set if the
system supports such a feature. This is generally considered
good practice these days, but if there is a need to pass file
descriptors to child processes the parent process must now
remember to clear the close-on-exec flag by calling fcntl(),
e.g. via ISO_C_BINDING, before executing the child process.
* The deprecated command-line option -fno-whole-file has been
removed. (-fwhole-file is the default since GCC 4.6.)
-fwhole-file/-fno-whole-file continue to be accepted but do not
influence the code generation.
* The compiler no longer unconditionally warns about DO loops with
zero iterations. This warning is now controlled by the -Wzerotrip
option, which is implied by -Wall.
* The new NO_ARG_CHECK attribute of the [25]!GCC$ directive can be
used to disable the type-kind-rank (TKR) argument check for a dummy
argument. The feature is similar to ISO/IEC TS 29133:2012's
TYPE(*), except that it additionally also disables the rank check.
Variables with NO_ARG_CHECK have to be dummy arguments and may only
be used as argument to ISO_C_BINDING's C_LOC and as actual argument
to another NO_ARG_CHECK dummy argument; also the other constraints
of TYPE(*) apply. The dummy arguments should be declared as scalar
or assumed-size variable of type type(*) (recommended) - or of type
integer, real, complex or logical. With NO_ARG_CHECK, a pointer to
the data without further type or shape information is passed,
similar to C's void*. Note that also TS 29113's
type(*),dimension(..) accepts arguments of any type and rank;
contrary to NO_ARG_CHECK assumed-rank arguments pass an array
descriptor which contains the array shape and stride of the
argument.
* [26]Fortran 2003:
+ Finalization is now supported. It is currently only done for a
subset of those situations in which it should occur.
+ Experimental support for scalar character components with
deferred length (i.e. allocatable string length) in derived
types has been added. (Deferred-length character variables are
supported since GCC 4.6.)
* [27]Fortran 2008:
+ When STOP or ERROR STOP are used to terminate the execution
and any exception (but inexact) is signaling, a warning is
printed to ERROR_UNIT, indicating which exceptions are
signaling. The [28]-ffpe-summary= command-line option can be
used to fine-tune for which exceptions the warning should be
shown.
+ Rounding on input (READ) is now handled on systems where
strtod honours the rounding mode. (For output, rounding is
supported since GCC 4.5.) Note that for input, the compatible
rounding mode is handled as nearest (i.e., rounding to an even
least significant [cf. IEC 60559:1989] for a tie, while
compatible rounds away from zero in that case).

[29]Go

* GCC 4.9 provides a complete implementation of the Go 1.2.1 release.

[30]New Targets and Target Specific Improvements

[31]AArch64

* The ARMv8-A crypto and CRC instructions are now supported through
intrinsics. These are enabled when the architecture supports these
and are available through the -march=armv8-a+crc and
-march=armv8-a+crypto options.
* Initial support for ILP32 has now been added to the compiler. This
is now available through the command-line option -mabi=ilp32.
Support for ILP32 is considered experimental as the ABI
specification is still beta.
* Coverage of more of the ISA including the SIMD extensions has been
added. The Advanced SIMD intrinsics have also been improved.
* The new local register allocator (LRA) is now on by default for the
AArch64 back end.
* The REE (Redundant extension elimination) pass has now been enabled
by default for the AArch64 back end.
* Tuning for the Cortex-A53 and Cortex-A57 has been improved.
* Initial big.LITTLE tuning support for the combination of Cortex-A57
and Cortex-A53 was added through the -mcpu=cortex-a57.cortex-a53
option.
* A number of structural changes have been made to both the ARM and
AArch64 back ends to facilitate improved code-generation.
* As of GCC 4.9.2 a workaround for the ARM Cortex-A53 erratum 835769
has been added and can be enabled by giving the
-mfix-cortex-a53-835769 option. Alternatively it can be enabled by
default by configuring GCC with the --enable-fix-cortex-a53-835769
option.

[32]ARC

* A port for Synopsys Designware ARC has been contributed by Embecosm
and Synopsys Inc.

[33]ARM

* Use of Advanced SIMD (Neon) for 64-bit scalar computations has been
disabled by default. This was found to generate better code in only
a small number of cases. It can be turned back on with the
-mneon-for-64bits option.
* Further support for the ARMv8-A architecture, notably implementing
the restriction around IT blocks in the Thumb32 instruction set has
been added. The -mrestrict-it option can be used with
-march=armv7-a or the -march=armv7ve options to make code
generation fully compatible with the deprecated instructions in
ARMv8-A.
* Support has now been added for the ARMv7ve variant of the
architecture. This can be used by the -march=armv7ve option.
* The ARMv8-A crypto and CRC instructions are now supported through
intrinsics and are available through the -march=armv8-a+crc and
mfpu=crypto-neon-fp-armv8 options.
* LRA is now on by default for the ARM target. This can be turned off
using the -mno-lra option. This option is a purely transitionary
command-line option and will be removed in a future release. We are
interested in any bug reports regarding functional and performance
regressions with LRA.
* A new option -mslow-flash-data to improve performance of programs
fetching data on slow flash memory has now been introduced for the
ARMv7-M profile cores.
* A new option -mpic-data-is-text-relative for targets that allows
data segments to be relative to text segments has been added. This
is on by default for all targets except VxWorks RTP.
* A number of infrastructural changes have been made to both the ARM
and AArch64 back ends to facilitate improved code-generation.
* GCC now supports Cortex-A12 and the Cortex-R7 through the
-mcpu=cortex-a12 and -mcpu=cortex-r7 options.
* GCC now has tuning for the Cortex-A57 and Cortex-A53 through the
-mcpu=cortex-a57 and -mcpu=cortex-a53 options.
* Initial big.LITTLE tuning support for the combination of Cortex-A57
and Cortex-A53 was added through the -mcpu=cortex-a57.cortex-a53
option. Similar support was added for the combination of Cortex-A15
and Cortex-A7 through the -mcpu=cortex-a15.cortex-a7 option.
* Further performance optimizations for the Cortex-A15 and the
Cortex-M4 have been added.
* A number of code generation improvements for Thumb2 to reduce code
size when compiling for the M-profile processors.

[34]AVR

* A new command-line option -mfract-convert-truncate has been added.
It allows compiler to use truncation instead of rounding towards
zero for fractional fixed-point types.

[35]IA-32/x86-64

* -mfpmath=sse is now implied by -ffast-math on all targets where
SSE2 is supported.
* Intel AVX-512 support was added to GCC. That includes inline
assembly support, new registers and extending existing ones, new
intrinsics (covered by corresponding testsuite), and basic
autovectorization. AVX-512 instructions are available via the
following GCC switches: AVX-512 foundation instructions: -mavx512f,
AVX-512 prefetch instructions: -mavx512pf, AVX-512 exponential and
reciprocal instructions: -mavx512er, AVX-512 conflict detection
instructions: -mavx512cd.
* It is now possible to call x86 intrinsics from select functions in
a file that are tagged with the corresponding target attribute
without having to compile the entire file with the -mxxx option.
This improves the usability of x86 intrinsics and is particularly
useful when doing [36]Function Multiversioning.
* GCC now supports the new Intel microarchitecture named Silvermont
through -march=silvermont.
* GCC now supports the new Intel microarchitecture named Broadwell
through -march=broadwell.
* Optimizing for other Intel microarchitectures have been renamed to
-march=nehalem, westmere, sandybridge, ivybridge, haswell, bonnell.
* -march=generic has been retuned for better support of Intel core
and AMD Bulldozer architectures. Performance of AMD K7, K8, Intel
Pentium-M, and Pentium4 based CPUs is no longer considered
important for generic.
* -mtune=intel can now be used to generate code running well on the
most current Intel processors, which are Haswell and Silvermont for
GCC 4.9.
* Support to encode 32-bit assembly instructions in 16-bit format is
now available through the -m16 command-line option.
* Better inlining of memcpy and memset that is aware of value ranges
and produces shorter alignment prologues.
* -mno-accumulate-outgoing-args is now honored when unwind
information is output. Argument accumulation is also now turned off
for portions of programs optimized for size.
* Support for new AMD family 15h processors (Excavator core) is now
available through the -march=bdver4 and -mtune=bdver4 options.

[37]MSP430

* A new command-line option -mcpu= has been added to the MSP430 back
end. This option is used to specify the ISA to be used. Accepted
values are msp430 (the default), msp430x and msp430xv2. The ISA is
no longer deduced from the -mmcu= option as there are far too many
different MCU names. The -mmcu= option is still supported, and this
is still used to select linker scripts and generate a C
preprocessor symbol that will be recognised by the msp430.h header
file.

[38]NDS32

* A new nds32 port supports the 32-bit architecture from Andes
Technology Corporation.
* The port provides initial support for the V2, V3, V3m instruction
set architectures.

[39]Nios II

* A port for the Altera Nios II has been contributed by Mentor
Graphics.

[40]PowerPC / PowerPC64 / RS6000

* GCC now supports Power ISA 2.07, which includes support for
Hardware Transactional Memory (HTM), Quadword atomics and several
VMX and VSX additions, including Crypto, 64-bit integer, 128-bit
integer and decimal integer operations.
* Support for the POWER8 processor is now available through the
-mcpu=power8 and -mtune=power8 options.
* The libitm library has been modified to add a HTM fastpath that
automatically uses POWER's HTM hardware instructions when it is
executing on a HTM enabled processor.
* Support for the new powerpc64le-linux platform has been added. It
defaults to generating code that conforms to the ELFV2 ABI.

S/390, System z

* Support for the Transactional Execution Facility included with the
IBM zEnterprise zEC12 processor has been added. A set of GCC style
builtins as well as XLC style builtins are provided. The builtins
are enabled by default when using the -march=zEC12 option but can
explicitly be disabled with -mno-htm. Using the GCC builtins also
libitm supports hardware transactions on S/390.
* The hotpatch features allows to prepare functions for hotpatching.
A certain amount of bytes is reserved before the function entry
label plus a NOP is inserted at its very beginning to implement a
backward jump when applying a patch. The feature can either be
enabled per compilation unit via the command-line option -mhotpatch
or per function using the hotpatch attribute.
* The shrink wrap optimization is now supported on S/390 and enabled
by default.
* A major rework of the routines to determine which registers need to
be saved and restored in function prologue/epilogue now allow to
use floating point registers as save slots. This will happen for
certain leaf function with -march=z10 or higher.
* The LRA rtl pass replaces reload by default on S/390.

[41]RX

* The port now allows to specify the RX100, RX200, and RX600
processors with the command-line options -mcpu=rx100, -mcpu=rx200
and -mcpu=rx600.

[42]SH

* Minor improvements to code generated for integer arithmetic and
code that involves the T bit.
* Added support for the SH2A clips and clipu instructions. The
compiler will now try to utilize them for min/max expressions such
as max (-128, min (127, x)).
* Added support for the cmp/str instruction through built-in
functions such as __builtin_strlen. When not optimizing for size,
the compiler will now expand calls to e.g. strlen as an inlined
sequences which utilize the cmp/str instruction.
* Improved code generated around volatile memory loads and stores.
* The option -mcbranchdi has been deprecated. Specifying it will
result in a warning and will not influence code generation.
* The option -mcmpeqdi has been deprecated. Specifying it will result
in a warning and will not influence code generation.

[43]GCC 4.9.1

This is the [44]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.9.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Version 4.0 of the OpenMP specification is supported even in Fortran,
not just C and C++.

[45]GCC 4.9.2

This is the [46]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.9.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[47]GCC 4.9.3

This is the [48]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.9.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[49]GCC 4.9.4

This is the [50]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.9.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

For questions related to the use of GCC, please consult these web
pages and the [51]GCC manuals. If that fails, the
[52][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [53][email protected]. All of [54]our lists have public
archives.

Copyright (C) [55]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [56]maintained by the GCC team. Last modified
2025-06-10.

References

1. https://gcc.gnu.org/ml/gcc-patches/2013-05/msg00728.html
2. https://gcc.gnu.org/PR60825
3. https://gcc.gnu.org/gcc-4.9/porting_to.html
4. https://gcc.gnu.org/gcc-4.9/changes.html#languages
5. https://www.openmp.org/specifications/
6. https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/Optimize-Options.html#index-fsimd-cost-model-908
7. https://gcc.gnu.org/gcc-4.9/changes.html#ada
8. https://gcc.gnu.org/gcc-4.9/changes.html#c-family
9. https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/Language-Independent-Options.html#index-fdiagnostics-color-252
10. https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/Loop-Specific-Pragmas.html
11. https://gcc.gnu.org/gcc-4.9/changes.html#c
12. https://gcc.gnu.org/gcc-4.9/changes.html#cxx
13. https://gcc.gnu.org/projects/cxx1y.html
14. https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3638.html
15. https://gcc.gnu.org/projects/cxx1y.html
16. https://gcc.gnu.org/projects/cxx1y.html
17. https://gcc.gnu.org/projects/cxx1y.html
18. https://gcc.gnu.org/projects/cxx1y.html
19. https://gcc.gnu.org/projects/cxx1y.html
20. https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n3889.pdf
21. https://gcc.gnu.org/onlinedocs/gcc-4.9.2/libstdc++/manual/manual/status.html#status.iso.2011
22. https://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#status.iso.2014
23. https://gcc.gnu.org/gcc-4.9/changes.html#fortran
24. https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gfortran/Argument-passing-conventions.html
25. https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gfortran/GNU-Fortran-Compiler-Directives.html
26. https://gcc.gnu.org/wiki/Fortran2003Status
27. https://gcc.gnu.org/wiki/Fortran2008Status
28. https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gfortran/Debugging-Options.html
29. https://gcc.gnu.org/gcc-4.9/changes.html#go
30. https://gcc.gnu.org/gcc-4.9/changes.html#targets
31. https://gcc.gnu.org/gcc-4.9/changes.html#aarch64
32. https://gcc.gnu.org/gcc-4.9/changes.html#arc
33. https://gcc.gnu.org/gcc-4.9/changes.html#arm
34. https://gcc.gnu.org/gcc-4.9/changes.html#avr
35. https://gcc.gnu.org/gcc-4.9/changes.html#x86
36. https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/Function-Multiversioning.html
37. https://gcc.gnu.org/gcc-4.9/changes.html#msp430
38. https://gcc.gnu.org/gcc-4.9/changes.html#nds32
39. https://gcc.gnu.org/gcc-4.9/changes.html#nios2
40. https://gcc.gnu.org/gcc-4.9/changes.html#powerpc
41. https://gcc.gnu.org/gcc-4.9/changes.html#rx
42. https://gcc.gnu.org/gcc-4.9/changes.html#sh
43. https://gcc.gnu.org/gcc-4.9/changes.html#GCC4.9.1
44. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.9.1
45. https://gcc.gnu.org/gcc-4.9/changes.html#GCC4.9.2
46. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.9.2
47. https://gcc.gnu.org/gcc-4.9/changes.html#GCC4.9.3
48. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.9.3
49. https://gcc.gnu.org/gcc-4.9/changes.html#GCC4.9.4
50. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.9.4
51. https://gcc.gnu.org/onlinedocs/
52. mailto:[email protected]
53. mailto:[email protected]
54. https://gcc.gnu.org/lists.html
55. https://www.fsf.org/
56. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.8/index.html

GCC 4.8 Release Series

(This release series is no longer supported.)

June 23, 2015

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 4.8.5.

This release is a bug-fix release, containing fixes for regressions in
GCC 4.8.4 relative to previous releases of GCC.

Release History

GCC 4.8.5
June 23, 2015 ([2]changes, [3]documentation)

GCC 4.8.4
December 19, 2014 ([4]changes, [5]documentation)

GCC 4.8.3
May 22, 2014 ([6]changes, [7]documentation)

GCC 4.8.2
October 16, 2013 ([8]changes, [9]documentation)

GCC 4.8.1
May 31, 2013 ([10]changes, [11]documentation)

GCC 4.8.0
March 22, 2013 ([12]changes, [13]documentation)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [14]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [15]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [16]GCC
project web site or contact the [17]GCC development mailing list.

To obtain GCC please use [18]our mirror sites or [19]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [20]GCC manuals. If that fails, the
[21][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [22][email protected]. All of [23]our lists have public
archives.

Copyright (C) [24]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [25]maintained by the GCC team. Last modified
2022-10-26.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-4.8/changes.html
3. https://gcc.gnu.org/onlinedocs/4.8.5/
4. https://gcc.gnu.org/gcc-4.8/changes.html
5. https://gcc.gnu.org/onlinedocs/4.8.4/
6. https://gcc.gnu.org/gcc-4.8/changes.html
7. https://gcc.gnu.org/onlinedocs/4.8.3/
8. https://gcc.gnu.org/gcc-4.8/changes.html
9. https://gcc.gnu.org/onlinedocs/4.8.2/
10. https://gcc.gnu.org/gcc-4.8/changes.html
11. https://gcc.gnu.org/onlinedocs/4.8.1/
12. https://gcc.gnu.org/gcc-4.8/changes.html
13. https://gcc.gnu.org/onlinedocs/4.8.0/
14. https://gcc.gnu.org/gcc-4.8/buildstat.html
15. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
16. https://gcc.gnu.org/index.html
17. mailto:[email protected]
18. https://gcc.gnu.org/mirrors.html
19. https://gcc.gnu.org/git.html
20. https://gcc.gnu.org/onlinedocs/
21. mailto:[email protected]
22. mailto:[email protected]
23. https://gcc.gnu.org/lists.html
24. https://www.fsf.org/
25. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.8/changes.html

GCC 4.8 Release Series
Changes, New Features, and Fixes

Caveats

GCC now uses C++ as its implementation language. This means that to
build GCC from sources, you will need a C++ compiler that understands
C++ 2003. For more details on the rationale and specific changes,
please refer to the [1]C++ conversion page.

To enable the Graphite framework for loop optimizations you now need
CLooG version 0.18.0 and ISL version 0.11.1. Both can be obtained from
the [2]GCC infrastructure directory. The installation manual contains
more information about requirements to build GCC.

GCC now uses a more aggressive analysis to derive an upper bound for
the number of iterations of loops using constraints imposed by language
standards. This may cause non-conforming programs to no longer work as
expected, such as SPEC CPU 2006 464.h264ref and 416.gamess. A new
option, -fno-aggressive-loop-optimizations, was added to disable this
aggressive analysis. In some loops that have known constant number of
iterations, but undefined behavior is known to occur in the loop before
reaching or during the last iteration, GCC will warn about the
undefined behavior in the loop instead of deriving lower upper bound of
the number of iterations for the loop. The warning can be disabled with
-Wno-aggressive-loop-optimizations.

On ARM, a bug has been fixed in GCC's implementation of the AAPCS rules
for the layout of vectors that could lead to wrong code being
generated. Vectors larger than 8 bytes in size are now by default
aligned to an 8-byte boundary. This is an ABI change: code that makes
explicit use of vector types may be incompatible with binary objects
built with older versions of GCC. Auto-vectorized code is not affected
by this change.

More information on porting to GCC 4.8 from previous versions of GCC
can be found in the [3]porting guide for this release.

General Optimizer Improvements (and Changes)

* DWARF4 is now the default when generating DWARF debug information.
When -g is used on a platform that uses DWARF debugging
information, GCC will now default to -gdwarf-4
-fno-debug-types-section.
GDB 7.5, Valgrind 3.8.0 and elfutils 0.154 debug information
consumers support DWARF4 by default. Before GCC 4.8 the default
version used was DWARF2. To make GCC 4.8 generate an older DWARF
version use -g together with -gdwarf-2 or -gdwarf-3. The default
for Darwin and VxWorks is still -gdwarf-2 -gstrict-dwarf.
* A new general optimization level, -Og, has been introduced. It
addresses the need for fast compilation and a superior debugging
experience while providing a reasonable level of run-time
performance. Overall experience for development should be better
than the default optimization level -O0.
* A new option -ftree-partial-pre was added to control the partial
redundancy elimination (PRE) optimization. This option is enabled
by default at the -O3 optimization level, and it makes PRE more
aggressive.
* The option -fconserve-space has been removed; it was no longer
useful on most targets since GCC supports putting variables into
BSS without making them common.
* The struct reorg and matrix reorg optimizations (command-line
options -fipa-struct-reorg and -fipa-matrix-reorg) have been
removed. They did not always work correctly, nor did they work with
link-time optimization (LTO), hence were only applicable to
programs consisting of a single translation unit.
* Several scalability bottle-necks have been removed from GCC's
optimization passes. Compilation of extremely large functions, e.g.
due to the use of the flatten attribute in the "Eigen" C++ linear
algebra templates library, is significantly faster than previous
releases of GCC.
* Link-time optimization (LTO) improvements:
+ LTO partitioning has been rewritten for better reliability and
maintanibility. Several important bugs leading to link
failures have been fixed.
* Interprocedural optimization improvements:
+ A new symbol table has been implemented. It builds on existing
callgraph and varpool modules and provide a new API. Unusual
symbol visibilities and aliases are handled more consistently
leading to, for example, more aggressive unreachable code
removal with LTO.
+ The inline heuristic can now bypass limits on the size of of
inlined functions when the inlining is particularly
profitable. This happens, for example, when loop bounds or
array strides get propagated.
+ Values passed through aggregates (either by value or
reference) are now propagated at the inter-procedural level
leading to better inlining decisions (for example in the case
of Fortran array descriptors) and devirtualization.
* [4]AddressSanitizer , a fast memory error detector, has been added
and can be enabled via -fsanitize=address. Memory access
instructions will be instrumented to detect heap-, stack-, and
global-buffer overflow as well as use-after-free bugs. To get nicer
stacktraces, use -fno-omit-frame-pointer. The AddressSanitizer is
available on IA-32/x86-64/x32/PowerPC/PowerPC64 GNU/Linux and on
x86-64 Darwin.
* [5]ThreadSanitizer has been added and can be enabled via
-fsanitize=thread. Instructions will be instrumented to detect data
races. The ThreadSanitizer is available on x86-64 GNU/Linux.
* A new local register allocator (LRA) has been implemented, which
replaces the 26 year old reload pass and improves generated code
quality. For now it is active on the IA-32 and x86-64 targets.
* Support for transactional memory has been implemented on the
following architectures: IA-32/x86-64, ARM, PowerPC, SH, SPARC, and
Alpha.

New Languages and Language specific improvements

C family

* Each diagnostic emitted now includes the original source line and a
caret '^' indicating the column. The option
-fno-diagnostics-show-caret suppresses this information.
* The option -ftrack-macro-expansion=2 is now enabled by default.
This allows the compiler to display the macro expansion stack in
diagnostics. Combined with the caret information, an example
diagnostic showing these two features is:

t.c:1:94: error: invalid operands to binary < (have `struct mystruct' and `float
')
#define MYMAX(A,B) __extension__ ({ __typeof__(A) __a = (A); __typeof__(B) _
_b = (B); __a < __b ? __b : __a; })

^
t.c:7:7: note: in expansion of macro 'MYMAX'
X = MYMAX(P, F);
^

* A new -Wsizeof-pointer-memaccess warning has been added (also
enabled by -Wall) to warn about suspicious length parameters to
certain string and memory built-in functions if the argument uses
sizeof. This warning warns e.g. about memset (ptr, 0, sizeof
(ptr)); if ptr is not an array, but a pointer, and suggests a
possible fix, or about memcpy (&foo, ptr, sizeof (&foo));.
* The new option -Wpedantic is an alias for -pedantic, which is now
deprecated. The forms -Wno-pedantic, -Werror=pedantic, and
-Wno-error=pedantic work in the same way as for any other -W
option. One caveat is that -Werror=pedantic is not equivalent to
-pedantic-errors, since the latter makes into errors some warnings
that are not controlled by -Wpedantic, and the former only affects
diagnostics that are disabled when using -Wno-pedantic.
* The option -Wshadow no longer warns if a declaration shadows a
function declaration, unless the former declares a function or
pointer to function, because this is [6]a common and valid case in
real-world code.

[7]C++

* G++ now implements the [8]C++11 thread_local keyword; this differs
from the GNU __thread keyword primarily in that it allows dynamic
initialization and destruction semantics. Unfortunately, this
support requires a run-time penalty for references to
non-function-local thread_local variables defined in a different
translation unit even if they don't need dynamic initialization, so
users may want to continue to use __thread for TLS variables with
static initialization semantics.
If the programmer can be sure that no use of the variable in a
non-defining TU needs to trigger dynamic initialization (either
because the variable is statically initialized, or a use of the
variable in the defining TU will be executed before any uses in
another TU), they can avoid this overhead with the
-fno-extern-tls-init option.
OpenMP threadprivate variables now also support dynamic
initialization and destruction by the same mechanism.
* G++ now implements the [9]C++11 attribute syntax, e.g.

[[noreturn]] void f();

and also the alignment specifier, e.g.

alignas(double) int i;

* G++ now implements [10]C++11 inheriting constructors, e.g.

struct A { A(int); };
struct B: A { using A::A; }; // defines B::B(int)
B b(42); // OK

* As of GCC 4.8.1, G++ implements the change to decltype semantics
from [11]N3276.

struct A f();
decltype(f()) g(); // OK, return type of f() is not required to be complete.

* As of GCC 4.8.1, G++ implements [12]C++11 ref-qualifiers, e.g.

struct A { int f() &; };
int i = A().f(); // error, f() requires an lvalue object

* G++ now supports a -std=c++1y option for experimentation with
features proposed for the next revision of the standard, expected
around 2014. Currently the only difference from -std=c++11 is
support for return type deduction in normal functions, as proposed
in [13]N3386. Status of C++1y features in GCC 4.8 can be found
[14]here.
* The G++ namespace association extension, __attribute ((strong)),
has been deprecated. Inline namespaces should be used instead.
* G++ now supports a -fext-numeric-literal option to control whether
GNU numeric literal suffixes are accepted as extensions or
processed as C++11 user-defined numeric literal suffixes. The flag
is on (use suffixes for GNU literals) by default for -std=gnu++*,
and -std=c++98. The flag is off (use suffixes for user-defined
literals) by default for -std=c++11 and later.

Runtime Library (libstdc++)

* [15]Improved experimental support for the new ISO C++ standard,
C++11, including:
+ forward_list meets the allocator-aware container requirements;
+ this_thread::sleep_for(), this_thread::sleep_until() and
this_thread::yield() are defined without requiring the
configure option --enable-libstdcxx-time;
* Improvements to <random>:
+ SSE optimized normal_distribution.
+ Use of hardware RNG instruction for random_device on new x86
processors (requires the assembler to support the
instruction.)
and <ext/random>:
+ New random number engine simd_fast_mersenne_twister_engine
with an optimized SSE implementation.
+ New random number distributions beta_distribution,
normal_mv_distribution, rice_distribution,
nakagami_distribution, pareto_distribution, k_distribution,
arcsine_distribution, hoyt_distribution.
* Added --disable-libstdcxx-verbose configure option to disable
diagnostic messages issued when a process terminates abnormally.
This may be useful for embedded systems to reduce the size of
executables that link statically to the library.

[16]Fortran

* Compatibility notice:
+ Module files: The version of module files (.mod) has been
incremented. Fortran MODULEs compiled by earlier GCC versions
have to be recompiled, when they are USEd by files compiled
with GCC 4.8. GCC 4.8 is not able to read .mod files created
by earlier versions; attempting to do so gives an error
message.
Note: The ABI of the produced assembler data itself has not
changed; object files and libraries are fully compatible with
older versions except as noted below.
+ ABI: Some internal names (used in the assembler/object file)
have changed for symbols declared in the specification part of
a module. If an affected module - or a file using it via use
association - is recompiled, the module and all files which
directly use such symbols have to be recompiled as well. This
change only affects the following kind of module symbols:
o Procedure pointers. Note: C-interoperable function
pointers (type(c_funptr)) are not affected nor are
procedure-pointer components.
o Deferred-length character strings.
* The [17]BACKTRACE intrinsic subroutine has been added. It shows a
backtrace at an arbitrary place in user code; program execution
continues normally afterwards.
* The [18]-Wc-binding-type warning option has been added (disabled by
default). It warns if the a variable might not be C interoperable;
in particular, if the variable has been declared using an intrinsic
type with default kind instead of using a kind parameter defined
for C interoperability in the intrinsic ISO_C_Binding module.
Before, this warning was always printed. The -Wc-binding-type
option is enabled by -Wall.
* The [19]-Wrealloc-lhs and -Wrealloc-lhs-all warning command-line
options have been added, which diagnose when code is inserted for
automatic (re)allocation of a variable during assignment. This
option can be used to decide whether it is safe to use
[20]-fno-realloc-lhs. Additionally, it can be used to find
automatic (re)allocation in hot loops. (For arrays, replacing
"var=" by "var(:)=" disables the automatic reallocation.)
* The [21]-Wcompare-reals command-line option has been added. When
this is set, warnings are issued when comparing REAL or COMPLEX
types for equality and inequality; consider replacing a == b by
abs(a-b) < eps with a suitable eps. -Wcompare-reals is enabled by
-Wextra.
* The [22]-Wtarget-lifetime command-line option has been added
(enabled with -Wall), which warns if the pointer in a pointer
assignment might outlive its target.
* Reading floating point numbers which use "q" for the exponential
(such as 4.0q0) is now supported as vendor extension for better
compatibility with old data files. It is strongly recommended to
use for I/O the equivalent but standard conforming "e" (such as
4.0e0).
(For Fortran source code, consider replacing the "q" in
floating-point literals by a kind parameter (e.g. 4.0e0_qp with a
suitable qp). Note that - in Fortran source code - replacing "q" by
a simple "e" is not equivalent.)
* The GFORTRAN_TMPDIR environment variable for specifying a
non-default directory for files opened with STATUS="SCRATCH", is
not used anymore. Instead gfortran checks the POSIX/GNU standard
TMPDIR environment variable. If TMPDIR is not defined, gfortran
falls back to other methods to determine the directory for
temporary files as documented in the [23]user manual.
* [24]Fortran 2003:
+ Support for unlimited polymorphic variables (CLASS(*)) has
been added. Nonconstant character lengths are not yet
supported.
* [25]TS 29113:
+ Assumed types (TYPE(*)) are now supported.
+ Experimental support for assumed-rank arrays (dimension(..))
has been added. Note that currently gfortran's own array
descriptor is used, which is different from the one defined in
TS29113, see [26]gfortran's header file or use the [27]Chasm
Language Interoperability Tools.

[28]Go

* GCC 4.8.2 provides a complete implementation of the Go 1.1.2
release.
* GCC 4.8.0 and 4.8.1 implement a preliminary version of the Go 1.1
release. The library support is not quite complete.
* Go has been tested on GNU/Linux and Solaris platforms for various
processors including x86, x86_64, PowerPC, SPARC, and Alpha. It may
work on other platforms as well.

[29]New Targets and Target Specific Improvements

[30]AArch64

* A new port has been added to support AArch64, the new 64-bit
architecture from ARM. Note that this is a separate port from the
existing 32-bit ARM port.
* The port provides initial support for the Cortex-A53 and the
Cortex-A57 processors with the command line options
-mcpu=cortex-a53 and -mcpu=cortex-a57.
* As of GCC 4.8.4 a workaround for the ARM Cortex-A53 erratum 835769
has been added and can be enabled by giving the
-mfix-cortex-a53-835769 option. Alternatively it can be enabled by
default by configuring GCC with the --enable-fix-cortex-a53-835769
option.

[31]ARM

* Initial support has been added for the AArch32 extensions defined
in the ARMv8 architecture.
* Code generation improvements for the Cortex-A7 and Cortex-A15 CPUs.
* A new option, -mcpu=marvell-pj4, has been added to generate code
for the Marvell PJ4 processor.
* The compiler can now automatically generate the VFMA, VFMS, REVSH
and REV16 instructions.
* A new vectorizer cost model for Advanced SIMD configurations to
improve the auto-vectorization strategies used.
* The scheduler now takes into account the number of live registers
to reduce the amount of spilling that can occur. This should
improve code performance in large functions. The limit can be
removed by using the option -fno-sched-pressure.
* Improvements have been made to the Marvell iWMMX code generation
and support for the iWMMX2 SIMD unit has been added. The option
-mcpu=iwmmxt2 can be used to enable code generation for the latter.
* A number of code generation improvements for Thumb2 to reduce code
size when compiling for the M-profile processors.
* The RTEMS (arm-rtems) port has been updated to use the EABI.
* Code generation support for the old FPA and Maverick floating-point
architectures has been removed. Ports that previously relied on
these features have also been removed. This includes the targets:
+ arm*-*-linux-gnu (use arm*-*-linux-gnueabi)
+ arm*-*-elf (use arm*-*-eabi)
+ arm*-*-uclinux* (use arm*-*-uclinux*eabi)
+ arm*-*-ecos-elf (no alternative)
+ arm*-*-freebsd (no alternative)
+ arm*-wince-pe* (no alternative).

[32]AVR

* Support for the command-line option -mshort-calls has been removed.
It was deprecated in GCC 4.7.
* The configure option --with-avrlibc supported since GCC 4.7.2 is
turned on per default for all non-RTEMS configurations. This option
arranges for a better integration of [33]AVR-LibC with avr-gcc. For
technical details, see [34]PR54461. To turn off the option in
non-AVR-LibC configurations, use --with-avrlibc=no. If the compiler
is configured for RTEMS, the option is always turned off.
* Support for the "Embedded C" fixed-point has been added. For
details, see the [35]GCC wiki and the [36]user manual. The support
is not complete.
* A new print modifier %r for register operands in inline assembler
is supported. It will print the raw register number without the
register prefix 'r':
/* Return the most significant byte of 'val', a 64-bit value. */

unsigned char msb (long long val)
{
unsigned char c;
__asm__ ("mov %0, %r1+7" : "=r" (c) : "r" (val));
return c;
}
The inline assembler in this example will generate code like
mov r24, 8+7
provided c is allocated to R24 and val is allocated to R8...R15.
This works because the GNU assembler accepts plain register numbers
without register prefix.
* Static initializers with 3-byte symbols are supported now:
extern const __memx char foo;
const __memx void *pfoo = &foo;
This requires at least Binutils 2.23.

IA-32/x86-64

* Allow -mpreferred-stack-boundary=3 for the x86-64 architecture with
SSE extensions disabled. Since the x86-64 ABI requires 16 byte
stack alignment, this is ABI incompatible and intended to be used
in controlled environments where stack space is an important
limitation. This option will lead to wrong code when functions
compiled with 16 byte stack alignment (such as functions from a
standard library) are called with misaligned stack. In this case,
SSE instructions may lead to misaligned memory access traps. In
addition, variable arguments will be handled incorrectly for 16
byte aligned objects (including x87 long double and __int128),
leading to wrong results. You must build all modules with
-mpreferred-stack-boundary=3, including any libraries. This
includes the system libraries and startup modules.
* Support for the new Intel processor codename Broadwell with RDSEED,
ADCX, ADOX, PREFETCHW is available through -madx, -mprfchw,
-mrdseed command-line options.
* Support for the Intel RTM and HLE intrinsics, built-in functions
and code generation is available via -mrtm and -mhle.
* Support for the Intel FXSR, XSAVE and XSAVEOPT instruction sets.
Intrinsics and built-in functions are available via -mfxsr, -mxsave
and -mxsaveopt respectively.
* New -maddress-mode=[short|long] options for x32.
-maddress-mode=short overrides default 64-bit addresses to 32-bit
by emitting the 0x67 address-size override prefix. This is the
default address mode for x32.
* New built-in functions to detect run-time CPU type and ISA:
+ A built-in function __builtin_cpu_is has been added to detect
if the run-time CPU is of a particular type. It returns a
positive integer on a match and zero otherwise. It accepts one
string literal argument, the CPU name. For example,
__builtin_cpu_is("westmere") returns a positive integer if the
run-time CPU is an Intel Core i7 Westmere processor. Please
refer to the [37]user manual for the list of valid CPU names
recognized.
+ A built-in function __builtin_cpu_supports has been added to
detect if the run-time CPU supports a particular ISA feature.
It returns a positive integer on a match and zero otherwise.
It accepts one string literal argument, the ISA feature. For
example, __builtin_cpu_supports("ssse3") returns a positive
integer if the run-time CPU supports SSSE3 instructions.
Please refer to the [38]user manual for the list of valid ISA
names recognized.
Caveat: If these built-in functions are called before any static
constructors are invoked, like during IFUNC initialization, then
the CPU detection initialization must be explicitly run using this
newly provided built-in function, __builtin_cpu_init. The
initialization needs to be done only once. For example, this is how
the invocation would look like inside an IFUNC initializer:
static void (*some_ifunc_resolver(void))(void)
{
__builtin_cpu_init();
if (__builtin_cpu_is("amdfam10h") ...
if (__builtin_cpu_supports("popcnt") ...
}

* Function Multiversioning Support with G++:
It is now possible to create multiple function versions each
targeting a specific processor and/or ISA. Function versions have
the same signature but different target attributes. For example,
here is a program with function versions:
__attribute__ ((target ("default")))
int foo(void)
{
return 1;
}

__attribute__ ((target ("sse4.2")))
int foo(void)
{
return 2;
}

int main (void)
{
int (*p) = &foo;
assert ((*p)() == foo());
return 0;
}

Please refer to this [39]wiki for more information.
* The x86 back end has been improved to allow option -fschedule-insns
to work reliably. This option can be used to schedule instructions
better and leads to improved performace in certain cases.
* Windows MinGW-w64 targets (*-w64-mingw*) require at least r5437
from the Mingw-w64 trunk.
* Support for new AMD family 15h processors (Steamroller core) is now
available through the -march=bdver3 and -mtune=bdver3 options.
* Support for new AMD family 16h processors (Jaguar core) is now
available through the -march=btver2 and -mtune=btver2 options.

[40]FRV

* This target now supports the -fstack-usage command-line option.

[41]MIPS

* GCC can now generate code specifically for the R4700, Broadcom XLP
and MIPS 34kn processors. The associated -march options are
-march=r4700, -march=xlp and -march=34kn respectively.
* GCC now generates better DSP code for MIPS 74k cores thanks to
further scheduling optimizations.
* The MIPS port now supports the -fstack-check option.
* GCC now passes the -mmcu and -mno-mcu options to the assembler.
* Previous versions of GCC would silently accept -fpic and -fPIC for
-mno-abicalls targets like mips*-elf. This combination was not
intended or supported, and did not generate position-independent
code. GCC 4.8 now reports an error when this combination is used.

[42]PowerPC / PowerPC64 / RS6000

* SVR4 configurations (GNU/Linux, FreeBSD, NetBSD) no longer save,
restore or update the VRSAVE register by default. The respective
operating systems manage the VRSAVE register directly.
* Large TOC support has been added for AIX through the command line
option -mcmodel=large.
* Native Thread-Local Storage support has been added for AIX.
* VMX (Altivec) and VSX instruction sets now are enabled implicitly
when targetting processors that support those hardware features on
AIX 6.1 and above.

[43]RX

* This target will now issue a warning message whenever multiple fast
interrupt handlers are found in the same compilation unit. This
feature can be turned off by the new
-mno-warn-multiple-fast-interrupts command-line option.

S/390, System z

* Support for the IBM zEnterprise zEC12 processor has been added.
When using the -march=zEC12 option, the compiler will generate code
making use of the following new instructions:
+ load and trap instructions
+ 2 new compare and trap instructions
+ rotate and insert selected bits - without CC clobber
The -mtune=zEC12 option enables zEC12 specific instruction
scheduling without making use of new instructions.
* Register pressure sensitive instruction scheduling is enabled by
default.
* The ifunc function attribute is enabled by default.
* memcpy and memcmp invokations on big memory chunks or with run time
lengths are not generated inline anymore when tuning for z10 or
higher. The purpose is to make use of the IFUNC optimized versions
in Glibc.

[44]SH

* The default alignment settings have been reduced to be less
aggressive. This results in more compact code for optimization
levels other than -Os.
* Improved support for the __atomic built-in functions:
+ A new option -matomic-model=model selects the model for the
generated atomic sequences. The following models are
supported:

soft-gusa
Software gUSA sequences (SH3* and SH4* only). On
SH4A targets this will now also partially utilize
the movco.l and movli.l instructions. This is the
default when the target is sh3*-*-linux* or
sh4*-*-linux*.

hard-llcs
Hardware movco.l / movli.l sequences (SH4A only).

soft-tcb
Software thread control block sequences.

soft-imask
Software interrupt flipping sequences (privileged
mode only). This is the default when the target is
sh1*-*-linux* or sh2*-*-linux*.

none
Generates function calls to the respective __atomic
built-in functions. This is the default for SH64
targets or when the target is not sh*-*-linux*.

+ The option -msoft-atomic has been deprecated. It is now an
alias for -matomic-model=soft-gusa.
+ A new option -mtas makes the compiler generate the tas.b
instruction for the __atomic_test_and_set built-in function
regardless of the selected atomic model.
+ The __sync functions in libgcc now reflect the selected atomic
model when building the toolchain.
* Added support for the mov.b and mov.w instructions with
displacement addressing.
* Added support for the SH2A instructions movu.b and movu.w.
* Various improvements to code generated for integer arithmetic.
* Improvements to conditional branches and code that involves the T
bit. A new option -mzdcbranch tells the compiler to favor
zero-displacement branches. This is enabled by default for SH4*
targets.
* The pref instruction will now be emitted by the __builtin_prefetch
built-in function for SH3* targets.
* The fmac instruction will now be emitted by the fmaf standard
function and the __builtin_fmaf built-in function.
* The -mfused-madd option has been deprecated in favor of the
machine-independent -ffp-contract option. Notice that the fmac
instruction will now be generated by default for expressions like a
* b + c. This is due to the compiler default setting
-ffp-contract=fast.
* Added new options -mfsrra and -mfsca to allow the compiler using
the fsrra and fsca instructions on targets other than SH4A (where
they are already enabled by default).
* Added support for the __builtin_bswap32 built-in function. It is
now expanded as a sequence of swap.b and swap.w instructions
instead of a library function call.
* The behavior of the -mieee option has been fixed and the negative
form -mno-ieee has been added to control the IEEE conformance of
floating point comparisons. By default -mieee is now enabled and
the option -ffinite-math-only implicitly sets -mno-ieee.
* Added support for the built-in functions __builtin_thread_pointer
and __builtin_set_thread_pointer. This assumes that GBR is used to
hold the thread pointer of the current thread. Memory loads and
stores relative to the address returned by __builtin_thread_pointer
will now also utilize GBR based displacement address modes.
* The -mdiv= option for targets other than SHmedia has been fixed and
documented.

[45]SPARC

* Added optimized instruction scheduling for Niagara4.

[46]TILE-Gx

* Added support for the -mcmodel=MODEL command-line option. The
models supported are small and large.

[47]V850

* This target now supports the E3V5 architecture via the use of the
new -mv850e3v5 command-line option. It also has experimental
support for the e3v5 LOOP instruction which can be enabled via the
new -mloop command-line option.

[48]XStormy16

* This target now supports the -fstack-usage command-line option.

[49]Operating Systems

[50]OpenBSD

* Support for OpenBSD/amd64 (x86_64-*-openbsd*) has been added and
support for OpenBSD/i386 (i386-*-openbsd*) has been rejuvenated.

[51]Windows (Cygwin)

* Executables are now linked against shared libgcc by default. The
previous default was to link statically, which can still be done by
explicitly specifying -static or static-libgcc on the command line.
However it is strongly advised against, as it will cause problems
for any application that makes use of DLLs compiled by GCC. It
should be alright for a monolithic stand-alone application that
only links against the Windows DLLs, but offers little or no
benefit.

[52]GCC 4.8.1

This is the [53]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.8.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

The C++11 <chrono> std::chrono::system_clock and
std::chrono::steady_clock classes have changed ABI in GCC 4.8.1, they
both are now separate (never typedefs of each other), both use
std::chrono::nanoseconds resolution, on most GNU/Linux configurations
std::chrono::steady_clock is now finally monotonic, and both classes
are mangled differently than in the previous GCC releases.
std::chrono::system_clock::now() with std::chrono::microseconds resp.
std::chrono::seconds resolution is still exported for backwards
compatibility with default configured libstdc++. Note that libstdc++
configured with --enable-libstdcxx-time= used to be ABI incompatible
with default configured libstdc++ for those two classes and no ABI
compatibility can be offered for those configurations, so any C++11
code that uses those classes and has been compiled and linked against
libstdc++ configured with the non-default --enable-libstdcxx-time=
configuration option needs to be recompiled.

[54]GCC 4.8.2

This is the [55]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.8.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[56]GCC 4.8.3

This is the [57]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.8.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Support for the new powerpc64le-linux platform has been added. It
defaults to generating code that conforms to the ELFV2 ABI.

[58]GCC 4.8.4

This is the [59]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.8.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[60]GCC 4.8.5

This is the [61]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.8.5 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

For questions related to the use of GCC, please consult these web
pages and the [62]GCC manuals. If that fails, the
[63][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [64][email protected]. All of [65]our lists have public
archives.

Copyright (C) [66]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [67]maintained by the GCC team. Last modified
2025-02-28.

References

1. https://gcc.gnu.org/wiki/cxx-conversion
2. ftp://gcc.gnu.org/pub/gcc/infrastructure/
3. https://gcc.gnu.org/gcc-4.8/porting_to.html
4. https://github.com/google/sanitizers
5. https://code.google.com/archive/p/data-race-test/wikis/ThreadSanitizer.wiki
6. https://lkml.org/lkml/2006/11/28/239
7. https://gcc.gnu.org/gcc-4.8/changes.html#cxx
8. https://gcc.gnu.org/gcc-4.8/cxx0x_status.html
9. https://gcc.gnu.org/gcc-4.8/cxx0x_status.html
10. https://gcc.gnu.org/gcc-4.8/cxx0x_status.html
11. https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3276.pdf
12. https://gcc.gnu.org/gcc-4.8/cxx0x_status.html
13. https://www.open-std.org/JTC1/SC22/WG21/docs/papers/2012/n3386.html
14. https://gcc.gnu.org/projects/cxx1y.html
15. https://gcc.gnu.org/onlinedocs/gcc-4.8.4/libstdc++/manual/manual/status.html#status.iso.2011
16. https://gcc.gnu.org/gcc-4.8/changes.html#fortran
17. https://gcc.gnu.org/onlinedocs/gfortran/BACKTRACE.html
18. https://gcc.gnu.org/onlinedocs/gfortran/Error-and-Warning-Options.html
19. https://gcc.gnu.org/onlinedocs/gfortran/Error-and-Warning-Options.html
20. https://gcc.gnu.org/onlinedocs/gfortran/Code-Gen-Options.html
21. https://gcc.gnu.org/onlinedocs/gfortran/Error-and-Warning-Options.html
22. https://gcc.gnu.org/onlinedocs/gfortran/Error-and-Warning-Options.html
23. https://gcc.gnu.org/onlinedocs/gfortran/TMPDIR.html
24. https://gcc.gnu.org/wiki/Fortran2003Status
25. https://gcc.gnu.org/wiki/TS29113Status
26. https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=libgfortran/libgfortran.h
27. https://chasm-interop.sourceforge.net/
28. https://gcc.gnu.org/gcc-4.8/changes.html#go
29. https://gcc.gnu.org/gcc-4.8/changes.html#targets
30. https://gcc.gnu.org/gcc-4.8/changes.html#aarch64
31. https://gcc.gnu.org/gcc-4.8/changes.html#arm
32. https://gcc.gnu.org/gcc-4.8/changes.html#avr
33. http://www.nongnu.org/avr-libc/
34. https://gcc.gnu.org/PR54461
35. https://gcc.gnu.org/wiki/avr-gcc#Fixed-Point_Support
36. https://gcc.gnu.org/onlinedocs/gcc/Fixed-Point.html
37. https://gcc.gnu.org/onlinedocs/gcc/x86-Built-in-Functions.html
38. https://gcc.gnu.org/onlinedocs/gcc/x86-Built-in-Functions.html
39. https://gcc.gnu.org/wiki/FunctionMultiVersioning
40. https://gcc.gnu.org/gcc-4.8/changes.html#frv
41. https://gcc.gnu.org/gcc-4.8/changes.html#mips
42. https://gcc.gnu.org/gcc-4.8/changes.html#powerpc
43. https://gcc.gnu.org/gcc-4.8/changes.html#rx
44. https://gcc.gnu.org/gcc-4.8/changes.html#sh
45. https://gcc.gnu.org/gcc-4.8/changes.html#sparc
46. https://gcc.gnu.org/gcc-4.8/changes.html#tilegx
47. https://gcc.gnu.org/gcc-4.8/changes.html#v850
48. https://gcc.gnu.org/gcc-4.8/changes.html#xstormy16
49. https://gcc.gnu.org/gcc-4.8/changes.html#os
50. https://gcc.gnu.org/gcc-4.8/changes.html#openbsd
51. https://gcc.gnu.org/gcc-4.8/changes.html#windows
52. https://gcc.gnu.org/gcc-4.8/changes.html#GCC4.8.1
53. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.8.1
54. https://gcc.gnu.org/gcc-4.8/changes.html#GCC4.8.2
55. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.8.2
56. https://gcc.gnu.org/gcc-4.8/changes.html#GCC4.8.3
57. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.8.3
58. https://gcc.gnu.org/gcc-4.8/changes.html#GCC4.8.4
59. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.8.4
60. https://gcc.gnu.org/gcc-4.8/changes.html#GCC4.8.5
61. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.8.5
62. https://gcc.gnu.org/onlinedocs/
63. mailto:[email protected]
64. mailto:[email protected]
65. https://gcc.gnu.org/lists.html
66. https://www.fsf.org/
67. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.7/index.html

GCC 4.7 Release Series

(This release series is no longer supported.)

June 12, 2014

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 4.7.4.

This release is a bug-fix release, containing fixes for regressions in
GCC 4.7.3 relative to previous releases of GCC.

Release History

GCC 4.7.4
June 12, 2014 ([2]changes, [3]documentation)

GCC 4.7.3
April 11, 2013 ([4]changes, [5]documentation)

GCC 4.7.2
September 20, 2012 ([6]changes, [7]documentation)

GCC 4.7.1
June 14, 2012 ([8]changes, [9]documentation)

GCC 4.7.0
March 22, 2012 ([10]changes, [11]documentation)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [12]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [13]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [14]GCC
project web site or contact the [15]GCC development mailing list.

To obtain GCC please use [16]our mirror sites or [17]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [18]GCC manuals. If that fails, the
[19][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [20][email protected]. All of [21]our lists have public
archives.

Copyright (C) [22]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [23]maintained by the GCC team. Last modified
2022-10-26.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-4.7/changes.html
3. https://gcc.gnu.org/onlinedocs/4.7.4/
4. https://gcc.gnu.org/gcc-4.7/changes.html
5. https://gcc.gnu.org/onlinedocs/4.7.3/
6. https://gcc.gnu.org/gcc-4.7/changes.html
7. https://gcc.gnu.org/onlinedocs/4.7.2/
8. https://gcc.gnu.org/gcc-4.7/changes.html
9. https://gcc.gnu.org/onlinedocs/4.7.1/
10. https://gcc.gnu.org/gcc-4.7/changes.html
11. https://gcc.gnu.org/onlinedocs/4.7.0/
12. https://gcc.gnu.org/gcc-4.7/buildstat.html
13. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
14. https://gcc.gnu.org/index.html
15. mailto:[email protected]
16. https://gcc.gnu.org/mirrors.html
17. https://gcc.gnu.org/git.html
18. https://gcc.gnu.org/onlinedocs/
19. mailto:[email protected]
20. mailto:[email protected]
21. https://gcc.gnu.org/lists.html
22. https://www.fsf.org/
23. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.7/changes.html

GCC 4.7 Release Series
Changes, New Features, and Fixes

Caveats

* The -fconserve-space flag has been deprecated. The flag had no
effect for most targets: only targets without a global .bss section
and without support for switchable sections. Furthermore, the flag
only had an effect for G++, where it could result in wrong
semantics (please refer to the GCC manual for further details). The
flag will be removed in GCC 4.8
* Support for a number of older systems and recently unmaintained or
untested target ports of GCC has been declared obsolete in GCC 4.7.
Unless there is activity to revive them, the next release of GCC
will have their sources permanently removed.
All GCC ports for the following processor architectures have been
declared obsolete:
+ picoChip (picochip-*)
The following ports for individual systems on particular
architectures have been obsoleted:
+ IRIX 6.5 (mips-sgi-irix6.5)
+ MIPS OpenBSD (mips*-*-openbsd*)
+ Solaris 8 (*-*-solaris2.8). Details can be found in the
[1]announcement.
+ Tru64 UNIX V5.1 (alpha*-dec-osf5.1*)
* On ARM, when compiling for ARMv6 (but not ARMv6-M), ARMv7-A,
ARMv7-R, or ARMv7-M, the new option -munaligned-access is active by
default, which for some sources generates code that accesses memory
on unaligned addresses. This requires the kernel of those systems
to enable such accesses (controlled by CP15 register c1, refer to
ARM documentation). Alternatively, or for compatibility with
kernels where unaligned accesses are not supported, all code has to
be compiled with -mno-unaligned-access. Upstream Linux kernel
releases have automatically and unconditionally supported unaligned
accesses as emitted by GCC due to this option being active since
version 2.6.28.
* Support on ARM for the legacy floating-point accelerator (FPA) and
the mixed-endian floating-point format that it used has been
obsoleted. The ports that still use this format have been obsoleted
as well. Many legacy ARM ports already provide an alternative that
uses the VFP floating-point format. The obsolete ports will be
deleted in the next release.
The obsolete ports with alternatives are:
+ arm*-*-rtems (use arm*-*-rtemseabi)
+ arm*-*-linux-gnu (use arm*-*-linux-gnueabi)
+ arm*-*-elf (use arm*-*-eabi)
+ arm*-*-uclinux* (use arm*-*-uclinux*eabi)
Note, however, that these alternatives are not binary compatible
with their legacy counterparts (although some can support running
legacy applications).
The obsolete ports that currently lack a modern alternative are:
+ arm*-*-ecos-elf
+ arm*-*-freebsd
+ arm*-wince-pe*
New ports that support more recent versions of the architecture are
welcome.
* Support for the Maverick co-processor on ARM has been obsoleted.
Code to support it will be deleted in the next release.
* Support has been removed for Unix International threads on Solaris
2, so the --enable-threads=solaris configure option and the
-threads compiler option don't work any longer.
* Support has been removed for the Solaris BSD Compatibility Package,
which lives in /usr/ucbinclude and /usr/ucblib. It has been removed
from Solaris 11, and was only intended as a migration aid from
SunOS 4 to SunOS 5. The -compat-bsd compiler option is not
recognized any longer.
* The ARM port's -mwords-little-endian option has been deprecated. It
will be removed in a future release.
* Support has been removed for the NetWare x86 configuration
obsoleted in GCC 4.6.
* It is no longer possible to use the "l" constraint in MIPS16 asm
statements.
* GCC versions 4.7.0 and 4.7.1 had changes to the C++ standard
library which affected the ABI in C++11 mode: a data member was
added to std::list changing its size and altering the definitions
of some member functions, and std::pair's move constructor was
non-trivial which altered the calling convention for functions with
std::pair arguments or return types. The ABI incompatibilities have
been fixed for GCC version 4.7.2 but as a result C++11 code
compiled with GCC 4.7.0 or 4.7.1 may be incompatible with C++11
code compiled with different GCC versions and with C++98/C++03 code
compiled with any version.
* On ARM, a bug has been fixed in GCC's implementation of the AAPCS
rules for the layout of vectors that could lead to wrong code being
generated. Vectors larger than 8 bytes in size are now by default
aligned to an 8-byte boundary. This is an ABI change: code that
makes explicit use of vector types may be incompatible with binary
objects built with older versions of GCC. Auto-vectorized code is
not affected by this change. (This change affects GCC versions
4.7.2 and later.)
* More information on porting to GCC 4.7 from previous versions of
GCC can be found in the [2]porting guide for this release.

General Optimizer Improvements

* Support for a new parameter --param case-values-threshold=n was
added to allow users to control the cutoff between doing switch
statements as a series of if statements and using a jump table.
* Link-time optimization (LTO) improvements:
+ Improved scalability and reduced memory usage. Link time
optimization of Firefox now requires 3GB of RAM on a 64-bit
system, while over 8GB was needed previously. Linking time has
been improved, too. The serial stage of linking Firefox has
been sped up by about a factor of 10.
+ Reduced size of object files and temporary storage used during
linking.
+ Streaming performance (both outbound and inbound) has been
improved.
+ ld -r is now supported with LTO.
+ Several bug fixes, especially in symbol table handling and
merging.
* Interprocedural optimization improvements:
+ Heuristics now take into account that after inlining code will
be optimized out because of known values (or properties) of
function parameters. For example:
void foo(int a)
{
if (a > 10)
... huge code ...
}
void bar (void)
{
foo (0);
}

The call of foo will be inlined into bar even when optimizing
for code size. Constructs based on __builtin_constant_p are
now understood by the inliner and code size estimates are
evaluated a lot more realistically.
+ The representation of C++ virtual thunks and aliases (both
implicit and defined via the alias attribute) has been
re-engineered. Aliases no longer pose optimization barriers
and calls to an alias can be inlined and otherwise optimized.
+ The inter-procedural constant propagation pass has been
rewritten. It now performs generic function specialization.
For example when compiling the following:
void foo(bool flag)
{
if (flag)
... do something ...
else
... do something else ...
}
void bar (void)
{
foo (false);
foo (true);
foo (false);
foo (true);
foo (false);
foo (true);
}

GCC will now produce two copies of foo. One with flag being
true, while other with flag being false. This leads to
performance improvements previously possible only by inlining
all calls. Cloning causes a lot less code size growth.
* A string length optimization pass has been added. It attempts to
track string lengths and optimize various standard C string
functions like strlen, strchr, strcpy, strcat, stpcpy and their
_FORTIFY_SOURCE counterparts into faster alternatives. This pass is
enabled by default at -O2 or above, unless optimizing for size, and
can be disabled by the -fno-optimize-strlen option. The pass can
e.g. optimize
char *bar (const char *a)
{
size_t l = strlen (a) + 2;
char *p = malloc (l); if (p == NULL) return p;
strcpy (p, a); strcat (p, "/"); return p;
}

into:
char *bar (const char *a)
{
size_t tmp = strlen (a);
char *p = malloc (tmp + 2); if (p == NULL) return p;
memcpy (p, a, tmp); memcpy (p + tmp, "/", 2); return p;
}

or for hosted compilations where stpcpy is available in the runtime
and headers provide its prototype, e.g.
void foo (char *a, const char *b, const char *c, const char *d)
{
strcpy (a, b); strcat (a, c); strcat (a, d);
}

can be optimized into:
void foo (char *a, const char *b, const char *c, const char *d)
{
strcpy (stpcpy (stpcpy (a, b), c), d);
}

New Languages and Language specific improvements

* Version 3.1 of the OpenMP specification is now supported for the C,
C++, and Fortran compilers.

Ada

* The command-line option -feliminate-unused-debug-types has been
re-enabled by default, as it is for the other languages, leading to
a reduction in debug info size of 12.5% and more for relevant
cases, as well as to a small compilation speedup.

C family

* A new built-in, __builtin_assume_aligned, has been added, through
which the compiler can be hinted about pointer alignment and can
use it to improve generated code.
* A new warning option -Wunused-local-typedefs was added for C, C++,
Objective-C and Objective-C++. This warning diagnoses typedefs
locally defined in a function, and otherwise not used.
* A new experimental command-line option -ftrack-macro-expansion was
added for C, C++, Objective-C, Objective-C++ and Fortran. It allows
the compiler to emit diagnostic about the current macro expansion
stack when a compilation error occurs in a macro expansion.
* Experimental support for transactional memory has been added. It
includes support in the compiler, as well as a supporting runtime
library called libitm. To compile code with transactional memory
constructs, use the -fgnu-tm option.
Support is currently available for Alpha, ARM, PowerPC, SH, SPARC,
and 32-bit/64-bit x86 platforms.
For more details on transactional memory see [3]the GCC WiKi.
* Support for atomic operations specifying the C++11/C11 memory model
has been added. These new __atomic routines replace the existing
__sync built-in routines.
Atomic support is also available for memory blocks. Lock-free
instructions will be used if a memory block is the same size and
alignment as a supported integer type. Atomic operations which do
not have lock-free support are left as function calls. A set of
library functions is available on the GCC atomic wiki in the
"External Atomics Library" section.
For more details on the memory models and features, see the
[4]atomic wiki.
* When a binary operation is performed on vector types and one of the
operands is a uniform vector, it is possible to replace the vector
with the generating element. For example:
typedef int v4si __attribute__ ((vector_size (16)));
v4si res, a = {1,2,3,4};
int x;

res = 2 + a; /* means {2,2,2,2} + a */
res = a - x; /* means a - {x,x,x,x} */

[5]C

* There is support for some more features from the C11 revision of
the ISO C standard. GCC now accepts the options -std=c11 and
-std=gnu11, in addition to the previous -std=c1x and -std=gnu1x.
+ Unicode strings (previously supported only with options such
as -std=gnu11, now supported with -std=c11), and the
predefined macros __STDC_UTF_16__ and __STDC_UTF_32__.
+ Nonreturning functions (_Noreturn and <stdnoreturn.h>).
+ Alignment support (_Alignas, _Alignof, max_align_t,
<stdalign.h>).
+ A built-in function __builtin_complex is provided to support C
library implementation of the CMPLX family of macros.

[6]C++

* G++ now accepts the -std=c++11, -std=gnu++11, and -Wc++11-compat
options, which are equivalent to -std=c++0x, -std=gnu++0x, and
-Wc++0x-compat, respectively.
* G++ now implements [7]C++11 extended friend syntax:

template<class W>
class Q
{
static const int I = 2;
public:
friend W;
};

struct B
{
int ar[Q<B>::I];
};

* Thanks to Ville Voutilainen, G++ now implements [8]C++11 explicit
override control.

struct B {
virtual void f() const final;
virtual void f(int);
};

struct D : B {
void f() const; // error: D::f attempts to override final B::f
void f(long) override; // error: doesn't override anything
void f(int) override; // ok
};

struct E final { };
struct F: E { }; // error: deriving from final class

* G++ now implements [9]C++11 non-static data member initializers.

struct A {
int i = 42;
} a; // initializes a.i to 42

* Thanks to Ed Smith-Rowland, G++ now implements [10]C++11
user-defined literals.

// Not actually a good approximation. :)
constexpr long double operator"" _degrees (long double d) { return d * 0.0175; }
long double pi = 180.0_degrees;

* G++ now implements [11]C++11 alias-declarations.

template <class T> using Ptr = T*;
Ptr<int> ip; // decltype(ip) is int*

* Thanks to Ville Voutilainen and Pedro Lamar�o, G++ now implements
[12]C++11 delegating constructors.

struct A {
A(int);
A(): A(42) { } // delegate to the A(int) constructor
};

* G++ now fully implements C++11 atomic classes rather than just
integer derived classes.

class POD {
int a;
int b;
};
std::atomic<POD> my_atomic_POD;

* G++ now sets the predefined macro __cplusplus to the correct value,
199711L for C++98/03, and 201103L for C++11.
* G++ now correctly implements the two-phase lookup rules such that
an unqualified name used in a template must have an appropriate
declaration found either in scope at the point of definition of the
template or by argument-dependent lookup at the point of
instantiation. As a result, code that relies on a second
unqualified lookup at the point of instantiation to find functions
declared after the template or in dependent bases will be rejected.
The compiler will suggest ways to fix affected code, and using the
-fpermissive compiler flag will allow the code to compile with a
warning.

template <class T>
void f() { g(T()); } // error, g(int) not found by argument-dependent lookup
void g(int) { } // fix by moving this declaration before the declaration of f

template <class T>
struct A: T {
// error, B::g(B) not found by argument-dependent lookup
void f() { g(T()); } // fix by using this->g or A::g
};

struct B { void g(B); };

int main()
{
f<int>();
A<B>().f();
}

* G++ now properly re-uses stack space allocated for temporary
objects when their lifetime ends, which can significantly lower
stack consumption for some C++ functions. As a result of this, some
code with undefined behavior will now break:

const int &f(const int &i) { return i; }
...
const int &x = f(1);
const int &y = f(2);

Here, x refers to the temporary allocated to hold the 1 argument,
which only lives until the end of the initialization; it
immediately becomes a dangling reference. So the next statement
re-uses the stack slot to hold the 2 argument, and users of x get
that value instead.
Note that this should not cause any change of behavior for
temporaries of types with non-trivial destructors, as they are
already destroyed at end of full-expression; the change is that now
the storage is released as well.
* A new command-line option -Wdelete-non-virtual-dtor has been added
to warn when delete is used to destroy an instance of a class which
has virtual functions and non-virtual destructor. It is unsafe to
delete an instance of a derived class through a pointer to a base
class if the base class does not have a virtual destructor. This
warning is enabled by -Wall.
* A new command-line option -Wzero-as-null-pointer-constant has been
added to warn when a literal '0' is used as null pointer constant.
It can be useful to facilitate the conversion to nullptr in C++11.
* As per C++98, access-declarations are now deprecated by G++.
Using-declarations are to be used instead. Furthermore, some
efforts have been made to improve the support of class scope
using-declarations. In particular, using-declarations referring to
a dependent type now work as expected ([13]bug c++/14258).
* The ELF symbol visibility of a template instantiation is now
properly constrained by the visibility of its template arguments
([14]bug c++/35688).

Runtime Library (libstdc++)

* [15]Improved experimental support for the new ISO C++ standard,
C++11, including:
+ using noexcept in most of the library;
+ implementations of pointer_traits, allocator_traits and
scoped_allocator_adaptor;
+ uses-allocator construction for tuple;
+ vector meets the allocator-aware container requirements;
+ replacing monotonic_clock with steady_clock;
+ enabling the thread support library on most POSIX targets;
+ many small improvements to conform to the FDIS.
* Added --enable-clocale=newlib configure option.
* Debug Mode iterators for unordered associative containers.
* Avoid polluting the global namespace and do not include <unistd.h>.

[16]Fortran

* The compile flag [17]-fstack-arrays has been added, which causes
all local arrays to be put on stack memory. For some programs this
will improve the performance significantly. If your program uses
very large local arrays, it is possible that you will have to
extend your runtime limits for stack memory.
* The [18]-Ofast flag now also implies [19]-fno-protect-parens and
[20]-fstack-arrays.
* Front-end optimizations can now be selected by the
[21]-ffrontend-optimize option and deselected by the
-fno-frontend-optimize option.
* When front-end optimization removes a function call,
[22]-Wfunction-elimination warns about that.
* When performing front-end-optimization, the
[23]-faggressive-function-elimination option allows the removal of
duplicate function calls even for impure functions.
* The flag [24]-Wreal-q-constant has been added, which warns if
floating-point literals have been specified using q (such as
1.0q0); the q marker is now supported as a vendor extension to
denote quad precision (REAL(16) or, if not available, REAL(10)).
Consider using a kind parameter (such as in 1.0_qp) instead, which
can be obtained via [25]SELECTED_REAL_KIND.
* The GFORTRAN_USE_STDERR environment variable has been removed. GNU
Fortran now always prints error messages to standard error. If you
wish to redirect standard error, please consult the manual for your
OS, shell, batch environment etc. as appropriate.
* The -fdump-core option and GFORTRAN_ERROR_DUMPCORE environment
variable have been removed. When encountering a serious error,
gfortran will now always abort the program. Whether a core dump is
generated depends on the user environment settings; see the ulimit
-c setting for POSIX shells, limit coredumpsize for C shells, and
the [26]WER user-mode dumps settings on Windows.
* The [27]-fbacktrace option is now enabled by default. When
encountering a fatal error, gfortran will attempt to print a
backtrace to standard error before aborting. It can be disabled
with -fno-backtrace. Note: On POSIX targets with the addr2line
utility from GNU binutils, GNU Fortran can print a backtrace with
function name, file name, line number information in addition to
the addresses; otherwise only the addresses are printed.
* [28]Fortran 2003:
+ Generic interface names which have the same name as derived
types are now supported, which allows to write constructor
functions. Note that Fortran does not support static
constructor functions; only default initialization or an
explicit structure-constructor initialization are available.
+ [29]Polymorphic (class) arrays are now supported.
* [30]Fortran 2008:
+ Support for the DO CONCURRENT construct has been added, which
allows the user to specify that individual loop iterations
have no interdependencies.
+ [31]Coarrays: Full single-image support except for polymorphic
coarrays. Additionally, preliminary support for multiple
images via an MPI-based [32]coarray communication library has
been added. Note: The library version is not yet usable as
remote coarray access is not yet possible.
* [33]TS 29113:
+ New flag [34]-std=f2008ts permits programs that are expected
to conform to the Fortran 2008 standard and the draft
Technical Specification (TS) 29113 on Further Interoperability
of Fortran with C.
+ The OPTIONAL attribute is now allowed for dummy arguments of
BIND(C) procedures.
+ The RANK intrinsic has been added.
+ The implementation of the ASYNCHRONOUS attribute in GCC is
compatible with the candidate draft of TS 29113 (since GCC
4.6).

[35]Go

* GCC 4.7 implements the [36]Go 1 language standard. The library
support in 4.7.0 is not quite complete, due to release timing.
Release 4.7.1 includes complete support for Go 1. The Go library is
from the Go 1.0.1 release.
* Go has been tested on GNU/Linux and Solaris platforms. It may work
on other platforms as well.

[37]New Targets and Target Specific Improvements

[38]ARM

* GCC now supports the Cortex-A7 processor implementing the v7-a
version of the architecture using the option -mcpu=cortex-a7.
* The default vector size in auto-vectorization for NEON is now 128
bits. If vectorization fails thusly, the vectorizer tries again
with 64-bit vectors.
* A new option -mvectorize-with-neon-double was added to allow users
to change the vector size to 64 bits.

[39]AVR

* The AVR port's libgcc has been improved and its multilib structure
has been enhanced. As a result, all objects contributing to an
application must either be compiled with GCC versions up to 4.6.x
or with GCC versions 4.7.1 or later. If the compiler is used with
AVR-LibC, you need a version that supports the new layout, i.e.
implements [40]#35407.
* The -mshort-calls command-line option has been deprecated. It will
be removed in the GCC 4.8 release. See -mrelax for a replacement.
* The compiled code only references startup code that clears .bss and
the common section resp. initializes the .data and .rodata section
provided respective sections (or subsections thereof) are not
empty, see [41]PR18145. Applications that put all static storage
objects into non-standard sections and / or define all static
storage objects in assembler modules, must reference __do_clear_bss
resp. __do_copy_data by hand or undefine the symbol(s) by means of
-Wl,-u,__do_clear_bss resp. -Wl,-u,__do_copy_data.
* GCC now supports the XMEGA architecture. This requires GNU Binutils
2.22 or later.
* Support for the [42]named address spaces __flash, __flash1, ...,
__flash5 and __memx has been added. These address spaces locate
read-only data in flash memory and allow reading from flash memory
by means of ordinary C code, i.e. without the need of (inline)
assembler code:

const __flash int values[] = { 42, 31 };

int add_values (const __flash int *p, int i)
{
return values[i] + *p;
}

* Support has been added for the AVR-specific configure option
--with-avrlibc=yes in order to arrange for better integration of
[43]AVR-Libc. This configure option is supported in avr-gcc v4.7.2
and newer and will only take effect in non-RTEMS configurations. If
avr-gcc is configured for RTEMS, the option will be ignored which
is the same as specifying --with-avrlibc=no. See [44]PR54461 for
more technical details.
* Support for AVR-specific [45]built-in functions has been added.
* Support has been added for the signed and unsigned 24-bit scalar
integer types __int24 and __uint24.
* New command-line options -maccumulate-args, -mbranch-cost=cost and
-mstrict-X were added to allow better fine-tuning of code
optimization.
* The command-line option -fdata-sections now also takes affect on
the section names of variables with the progmem attribute.
* A new inline assembler print modifier %i to print a RAM address as
I/O address has been added:

#include <avr/io.h> /* Port Definitions from AVR-LibC */

void set_portb (uint8_t value)
{
asm volatile ("out %i0, %1" :: "n" (&PORTB), "r" (value) : "memory");
}

The offset between an I/O address and the RAM address for that I/O
location is device-specific. This offset is taken into account when
printing a RAM address with the %i modifier so that the address is
suitable to be used as operand in an I/O command. The address must
be a constant integer known at compile time.
* The inline assembler constraint "R" to represent integers in the
range -6 ... 5 has been removed without replacement.
* Many optimizations to:
+ 64-bit integer arithmetic
+ Widening multiplication
+ Integer division by a constant
+ Avoid constant reloading in multi-byte instructions.
+ Micro-optimizations for special instruction sequences.
+ Generic built-in functions like __builtin_ffs*,
__builtin_clz*, etc.
+ If-else decision trees generated by switch instructions
+ Merging of data located in flash memory
+ New libgcc variants for devices with 8-bit wide stack pointer
+ ...
* Better documentation:
+ Handling of EIND and indirect jumps on devices with more than
128 KiB of program memory.
+ Handling of the RAMPD, RAMPX, RAMPY and RAMPZ special function
registers.
+ Function attributes OS_main and OS_task.
+ AVR-specific built-in macros.

C6X

* Support has been added for the Texas Instruments C6X family of
processors.

CR16

* Support has been added for National Semiconductor's CR16
architecture.

Epiphany

* Support has been added for Adapteva's Epiphany architecture.

IA-32/x86-64

* Support for Intel AVX2 intrinsics, built-in functions and code
generation is available via -mavx2.
* Support for Intel BMI2 intrinsics, built-in functions and code
generation is available via -mbmi2.
* Implementation and automatic generation of __builtin_clz* using the
lzcnt instruction is available via -mlzcnt.
* Support for Intel FMA3 intrinsics and code generation is available
via -mfma.
* A new -mfsgsbase command-line option is available that makes GCC
generate new segment register read/write instructions through
dedicated built-ins.
* Support for the new Intel rdrnd instruction is available via
-mrdrnd.
* Two additional AVX vector conversion instructions are available via
-mf16c.
* Support for new Intel processor codename IvyBridge with RDRND,
FSGSBASE and F16C is available through -march=core-avx-i.
* Support for the new Intel processor codename Haswell with AVX2,
FMA, BMI, BMI2, LZCNT is available through -march=core-avx2.
* Support for new AMD family 15h processors (Piledriver core) is now
available through -march=bdver2 and -mtune=bdver2 options.
* Support for [46]the x32 psABI is now available through the -mx32
option.
* Windows mingw targets are using the -mms-bitfields option by
default.
* Windows x86 targets are using the __thiscall calling convention for
C++ class-member functions.
* Support for the configure option --with-threads=posix for Windows
mingw targets.

[47]MIPS

* GCC now supports thread-local storage (TLS) for MIPS16. This
requires GNU binutils 2.22 or later.
* GCC can now generate code specifically for the Cavium Octeon+ and
Octeon2 processors. The associated command-line options are
-march=octeon+ and -march=octeon2 respectively. Both options
require GNU binutils 2.22 or later.
* GCC can now work around certain 24k errata, under the control of
the command-line option -mfix-24k. These workarounds require GNU
binutils 2.20 or later.
* 32-bit MIPS GNU/Linux targets such as mips-linux-gnu can now build
n32 and n64 multilibs. The result is effectively a 64-bit GNU/Linux
toolchain that generates 32-bit code by default. Use the
configure-time option --enable-targets=all to select these extra
multilibs.
* Passing -fno-delayed-branch now also stops the assembler from
automatically filling delay slots.

PowerPC/PowerPC64

* Vectors of type vector long long or vector long are passed and
returned using the same method as other vectors with the VSX
instruction set. Previously GCC did not adhere to the ABI for
128-bit vectors with 64-bit integer base types (PR 48857). This
will also be fixed in the GCC 4.6.1 and 4.5.4 releases.
* A new option -mno-pointers-to-nested-functions was added to allow
AIX 32-bit/64-bit and GNU/Linux 64-bit PowerPC users to specify
that the compiler should not load up the chain register (r11)
before calling a function through a pointer. If you use this
option, you cannot call nested functions through a pointer, or call
other languages that might use the static chain.
* A new option msave-toc-indirect was added to allow AIX
32-bit/64-bit and GNU/Linux 64-bit PowerPC users control whether we
save the TOC in the prologue for indirect calls or generate the
save inline. This can speed up some programs that call through a
function pointer a lot, but it can slow down other functions that
only call through a function pointer in exceptional cases.
* The PowerPC port will now enable machine-specific built-in
functions when the user switches the target machine using the
#pragma GCC target or __attribute__ ((__target__ ("target"))) code
sequences. In addition, the target macros are updated. However, due
to the way the -save-temps switch is implemented, you won't see the
effect of these additional macros being defined in preprocessor
output.

SH

* A new option -msoft-atomic has been added. When it is specified,
GCC will generate GNU/Linux-compatible gUSA atomic sequences for
the new __atomic routines.
* Since it is neither supported by GAS nor officially documented,
code generation for little endian SH2A has been disabled.
Specifying -ml with -m2a* will now result in a compiler error.
* The defunct -mbranch-cost option has been fixed.
* Some improvements to the generated code of:
+ Utilization of the tst #imm,R0 instruction.
+ Dynamic shift instructions on SH2A.
+ Integer absolute value calculations.
* The -mdiv= option for targets other than SHmedia has been fixed and
documented.

SPARC

* The option -mflat has been reinstated. When it is specified, the
compiler will generate code for a single register window model.
This is essentially a new implementation and the corresponding
debugger support has been added to GDB 7.4.
* Support for the options -mtune=native and -mcpu=native has been
added on selected native platforms (GNU/Linux and Solaris).
* Support for the SPARC T3 (Niagara 3) processor has been added.
* VIS:
+ An intrinsics header visintrin.h has been added.
+ Builtin intrinsics for the VIS 1.0 edge handling and pixel
compare instructions have been added.
+ The little-endian version of alignaddr is now supported.
+ When possible, VIS builtins are marked const, which should
increase the compiler's ability to optimize VIS operations.
+ The compiler now properly tracks the %gsr register and how it
behaves as an input for various VIS instructions.
+ Akin to fzero, the compiler can now generate fone instructions
in order to set all of the bits of a floating-point register
to 1.
+ The documentation for the VIS intrinsics in the GCC manual has
been brought up to date and many inaccuracies were fixed.
+ Intrinsics for the VIS 2.0 bmask, bshuffle, and
non-condition-code setting edge instructions have been added.
Their availability is controlled by the new -mvis2 and
-mno-vis2 options. They are enabled by default on
UltraSPARC-III and later CPUs.
* Support for UltraSPARC Fused Multiply-Add floating-point extensions
has been added. These instructions are enabled by default on SPARC
T3 (Niagara 3) and later CPUs.

TILE-Gx/TILEPro

* Support has been added for the Tilera TILE-Gx and TILEPro families
of processors.

Other significant improvements

* A new option (-grecord-gcc-switches) was added that appends
compiler command-line options that might affect code generation to
the DW_AT_producer attribute string in the DWARF debugging
information.
* GCC now supports various new GNU extensions to the DWARF debugging
information format, like [48]entry value and [49]call site
information, [50]typed DWARF stack or [51]a more compact macro
representation. Support for these extensions has been added to GDB
7.4. They can be disabled through the -gstrict-dwarf command-line
option.

[52]GCC 4.7.1

This is the [53]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.7.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

The Go front end in the 4.7.1 release fully supports the [54]Go 1
language standard.

[55]GCC 4.7.2

This is the [56]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.7.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[57]GCC 4.7.3

This is the [58]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.7.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[59]GCC 4.7.4

This is the [60]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.7.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

For questions related to the use of GCC, please consult these web
pages and the [61]GCC manuals. If that fails, the
[62][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [63][email protected]. All of [64]our lists have public
archives.

Copyright (C) [65]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [66]maintained by the GCC team. Last modified
2025-06-10.

References

1. https://gcc.gnu.org/ml/gcc-patches/2011-03/msg01263.html
2. https://gcc.gnu.org/gcc-4.7/porting_to.html
3. https://gcc.gnu.org/wiki/TransactionalMemory
4. https://gcc.gnu.org/wiki/Atomic/GCCMM
5. https://gcc.gnu.org/gcc-4.7/changes.html#c
6. https://gcc.gnu.org/gcc-4.7/changes.html#cxx
7. https://gcc.gnu.org/gcc-4.7/cxx0x_status.html
8. https://gcc.gnu.org/gcc-4.7/cxx0x_status.html
9. https://gcc.gnu.org/gcc-4.7/cxx0x_status.html
10. https://gcc.gnu.org/gcc-4.7/cxx0x_status.html
11. https://gcc.gnu.org/gcc-4.7/cxx0x_status.html
12. https://gcc.gnu.org/gcc-4.7/cxx0x_status.html
13. https://gcc.gnu.org/PR14258
14. https://gcc.gnu.org/PR35688
15. https://gcc.gnu.org/onlinedocs/gcc-4.7.4/libstdc++/manual/manual/status.html#status.iso.2011
16. https://gcc.gnu.org/gcc-4.7/changes.html#fortran
17. https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gfortran/Code-Gen-Options.html#index-g_t_0040code_007bfstack-arrays_007d-254
18. https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gcc/Optimize-Options.html#index-Ofast-689
19. https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gfortran/Code-Gen-Options.html#index-g_t_0040code_007bfno-protect-parens_007d-270
20. https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gfortran/Code-Gen-Options.html#index-g_t_0040code_007bfstack-arrays_007d-254
21. https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gfortran/Code-Gen-Options.html#index-g_t_0040code_007bfrontend-optimize_007d-275
22. https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gfortran/Error-and-Warning-Options.html#index-g_t_0040code_007bWfunction-elimination_007d-170
23. https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gfortran/Code-Gen-Options.html#index-g_t_0040code_007bfaggressive-function-elimination_007d-270
24. https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gfortran/Error-and-Warning-Options.html#index-g_t_0040code_007bWreal-q-constant_007d-149
25. https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gfortran/SELECTED_005fREAL_005fKIND.html
26. https://learn.microsoft.com/en-us/windows/win32/wer/collecting-user-mode-dumps
27. https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gfortran/Debugging-Options.html#index-g_t_0040code_007bfno-backtrace_007d-183
28. https://gcc.gnu.org/wiki/Fortran2003Status
29. https://gcc.gnu.org/wiki/OOP
30. https://gcc.gnu.org/wiki/Fortran2008Status
31. https://gcc.gnu.org/wiki/Coarray
32. https://gcc.gnu.org/wiki/CoarrayLib
33. https://gcc.gnu.org/wiki/TS29113Status
34. https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gfortran/Fortran-Dialect-Options.html#index-g_t_0040code_007bstd_003d_007d_0040var_007bstd_007d-option-53
35. https://gcc.gnu.org/gcc-4.7/changes.html#go
36. https://go.dev/doc/go1
37. https://gcc.gnu.org/gcc-4.7/changes.html#targets
38. https://gcc.gnu.org/gcc-4.7/changes.html#arm
39. https://gcc.gnu.org/gcc-4.7/changes.html#avr
40. http://savannah.nongnu.org/bugs/?35407
41. https://gcc.gnu.org/PR18145
42. https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gcc/Named-Address-Spaces.html
43. http://www.nongnu.org/avr-libc/
44. https://gcc.gnu.org/PR54461
45. https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gcc/AVR-Built%5f002din-Functions.html
46. https://sites.google.com/site/x32abi/
47. https://gcc.gnu.org/gcc-4.7/changes.html#mips
48. https://dwarfstd.org/issues/100909.1.html
49. https://dwarfstd.org/issues/100909.2.html
50. https://dwarfstd.org/issues/140425.1.html
51. https://dwarfstd.org/issues/110722.1.html
52. https://gcc.gnu.org/gcc-4.7/changes.html#GCC4.7.1
53. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.7.1
54. https://go.dev/doc/go1
55. https://gcc.gnu.org/gcc-4.7/changes.html#GCC4.7.2
56. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.7.2
57. https://gcc.gnu.org/gcc-4.7/changes.html#GCC4.7.3
58. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.7.3
59. https://gcc.gnu.org/gcc-4.7/changes.html#GCC4.7.4
60. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.7.4
61. https://gcc.gnu.org/onlinedocs/
62. mailto:[email protected]
63. mailto:[email protected]
64. https://gcc.gnu.org/lists.html
65. https://www.fsf.org/
66. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.6/index.html

GCC 4.6 Release Series

(This release series is no longer supported.)

April 12, 2013

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 4.6.4.

This release is a bug-fix release, containing fixes for regressions in
GCC 4.6.3 relative to previous releases of GCC.

Release History

GCC 4.6.4
April 12, 2013 ([2]changes, [3]documentation)

GCC 4.6.3
March 1, 2012 ([4]changes, [5]documentation)

GCC 4.6.2
October 26, 2011 ([6]changes, [7]documentation)

GCC 4.6.1
June 27, 2011 ([8]changes, [9]documentation)

GCC 4.6.0
March 25, 2011 ([10]changes, [11]documentation)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [12]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [13]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [14]GCC
project web site or contact the [15]GCC development mailing list.

To obtain GCC please use [16]our mirror sites or [17]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [18]GCC manuals. If that fails, the
[19][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [20][email protected]. All of [21]our lists have public
archives.

Copyright (C) [22]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [23]maintained by the GCC team. Last modified
2022-10-26.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-4.6/changes.html
3. https://gcc.gnu.org/onlinedocs/4.6.4/
4. https://gcc.gnu.org/gcc-4.6/changes.html
5. https://gcc.gnu.org/onlinedocs/4.6.3/
6. https://gcc.gnu.org/gcc-4.6/changes.html
7. https://gcc.gnu.org/onlinedocs/4.6.2/
8. https://gcc.gnu.org/gcc-4.6/changes.html
9. https://gcc.gnu.org/onlinedocs/4.6.1/
10. https://gcc.gnu.org/gcc-4.6/changes.html
11. https://gcc.gnu.org/onlinedocs/4.6.0/
12. https://gcc.gnu.org/gcc-4.6/buildstat.html
13. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
14. https://gcc.gnu.org/index.html
15. mailto:[email protected]
16. https://gcc.gnu.org/mirrors.html
17. https://gcc.gnu.org/git.html
18. https://gcc.gnu.org/onlinedocs/
19. mailto:[email protected]
20. mailto:[email protected]
21. https://gcc.gnu.org/lists.html
22. https://www.fsf.org/
23. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.6/changes.html

GCC 4.6 Release Series
Changes, New Features, and Fixes

Caveats

* The options -b <machine> and -V <version> have been removed because
they were unreliable. Instead, users should directly run
<machine>-gcc when cross-compiling, or <machine>-gcc-<version> to
run a different version of gcc.
* GCC now has stricter checks for invalid command-line options. In
particular, when gcc was called to link object files rather than
compile source code, it would previously accept and ignore all
options starting with --, including linker options such as
--as-needed and --export-dynamic, although such options would
result in errors if any source code was compiled. Such options, if
unknown to the compiler, are now rejected in all cases; if the
intent was to pass them to the linker, options such as
-Wl,--as-needed should be used.
* Versions of the GNU C library up to and including 2.11.1 included
an [1]incorrect implementation of the cproj function. GCC optimizes
its builtin cproj according to the behavior specified and allowed
by the ISO C99 standard. If you want to avoid discrepancies between
the C library and GCC's builtin transformations when using cproj in
your code, use GLIBC 2.12 or later. If you are using an older GLIBC
and actually rely on the incorrect behavior of cproj, then you can
disable GCC's transformations using -fno-builtin-cproj.
* The C-only intermodule optimization framework (IMA, enabled by
-combine) has been removed in favor of the new generic link-time
optimization framework (LTO) introduced in [2]GCC 4.5.0.
* GCC now ships with the LGPL-licensed libquadmath library, which
provides quad-precision mathematical functions for targets with a
__float128 datatype. __float128 is available for targets on 32-bit
x86, x86-64 and Itanium architectures. The libquadmath library is
automatically built on such targets when building the Fortran
compiler.
* New -Wunused-but-set-variable and -Wunused-but-set-parameter
warnings were added for C, C++, Objective-C and Objective-C++.
These warnings diagnose variables respective parameters which are
only set in the code and never otherwise used. Usually such
variables are useless and often even the value assigned to them is
computed needlessly, sometimes expensively. The
-Wunused-but-set-variable warning is enabled by default by -Wall
flag and -Wunused-but-set-parameter by -Wall -Wextra flags.
* On ARM, a bug has been fixed in GCC's implementation of the AAPCS
rules for the layout of vectors that could lead to wrong code being
generated. Vectors larger than 8 bytes in size are now by default
aligned to an 8-byte boundary. This is an ABI change: code that
makes explicit use of vector types may be incompatible with binary
objects built with older versions of GCC. Auto-vectorized code is
not affected by this change. (This change affects GCC versions
4.6.4 and later, with the exception of versions 4.7.0 and 4.7.1.)
* On AVR, variables with the progmem attribute to locate data in
flash memory must be qualified as const.
* Support for a number of older systems and recently unmaintained or
untested target ports of GCC has been declared obsolete in GCC 4.6.
Unless there is activity to revive them, the next release of GCC
will have their sources permanently removed.
All GCC ports for the following processor architectures have been
declared obsolete:
+ Argonaut ARC (arc-*)
+ National Semiconductor CRX (crx-*)
+ Motorola 68HC11 and 68HC12 (m68hc11-*-*, m6811-*-*,
m68hc12-*-*, m6812-*-*)
+ Sunplus S+core (score-*)
The following ports for individual systems on particular
architectures have been obsoleted:
+ Interix (i[34567]86-*-interix3*)
+ NetWare x86 (i[3456x]86-*-netware*)
+ Generic ARM PE (arm-*-pe* other than arm*-wince-pe*)
+ MCore PE (mcore-*-pe*)
+ SH SymbianOS (sh*-*-symbianelf*)
+ GNU Hurd on Alpha and PowerPC (alpha*-*-gnu*, powerpc*-*-gnu*)
+ M68K uClinux old ABI (m68k-*-uclinuxoldabi*)
+ a.out NetBSD (arm*-*-netbsd*, i[34567]86-*-netbsd*,
vax-*-netbsd*, but not *-*-netbsdelf*)
The i[34567]86-*-pe alias for Cygwin targets has also been
obsoleted; users should configure for i[34567]86-*-cygwin* instead.
Certain configure options to control the set of libraries built
with GCC on some targets have been obsoleted. On ARM targets, the
options --disable-fpu, --disable-26bit, --disable-underscore,
--disable-interwork, --disable-biendian and --disable-nofmult have
been obsoleted. On MIPS targets, the options
--disable-single-float, --disable-biendian and --disable-softfloat
have been obsoleted.
* Support has been removed for all the [3]configurations obsoleted in
GCC 4.5.
* More information on porting to GCC 4.6 from previous versions of
GCC can be found in the [4]porting guide for this release.

General Optimizer Improvements

* A new general optimization level, -Ofast, has been introduced. It
combines the existing optimization level -O3 with options that can
affect standards compliance but result in better optimized code.
For example, -Ofast enables -ffast-math.
* Link-time optimization improvements:
+ The [5]Scalable Whole Program Optimizer (WHOPR) project has
stabilized to the point of being usable. It has become the
default mode when using the LTO optimization model. Link time
optimization can now split itself into multiple parallel
compilations. Parallelism is controlled with -flto=n (where n
specifies the number of compilations to execute in parallel).
GCC can also cooperate with a GNU make job server by
specifying the -flto=jobserver option and adding + to the
beginning of the Makefile rule executing the linker.
Classical LTO mode can be enforced by -flto-partition=none.
This may result in small code quality improvements.
+ A large number of bugs were fixed. GCC itself, Mozilla Firefox
and other large applications can be built with LTO enabled.
+ The linker plugin support improvements
o Linker plugin is now enabled by default when the linker
is detected to have plugin support. This is the case for
GNU ld 2.21.51 or newer (on ELF and Cygwin targets) and
the Gold linker on ELF targets. Plugin support of the
Apple linker on Darwin is not compatible with GCC. The
linker plugin can also be controlled by the
-fuse-linker-plugin command-line option.
o Resolution information from the linker plugin is used to
drive whole program assumptions. Use of the linker plugin
results in more aggressive optimization on binaries and
on shared libraries that use the hidden visibility
attribute. Consequently the use of -fwhole-program is not
necessary in addition to LTO.
+ Hidden symbols used from non-LTO objects now have to be
explicitly annotated with externally_visible when the linker
plugin is not used.
+ C++ inline functions and virtual tables are now privatized
more aggressively, leading to better inter-procedural
optimization and faster dynamic linking.
+ Memory usage and intermediate language streaming performance
have been improved.
+ Static constructors and destructors from individual units are
inlined into a single function. This can significantly improve
startup times of large C++ applications where static
constructors are very common. For example, static constructors
are used when including the iostream header.
+ Support for the Ada language has been added.
* Interprocedural optimization improvements
+ The interprocedural framework was re-tuned for link time
optimization. Several scalability issues were resolved.
+ Improved auto-detection of const and pure functions. Newly,
noreturn functions are auto-detected.
The [6]-Wsuggest-attribute=[const|pure|noreturn] flag is
available that informs users when adding attributes to headers
might improve code generation.
+ A number of inlining heuristic improvements. In particular:
o Partial inlining is now supported and enabled by default
at -O2 and greater. The feature can be controlled via
-fpartial-inlining.
Partial inlining splits functions with short hot path to
return. This allows more aggressive inlining of the hot
path leading to better performance and often to code size
reductions (because cold parts of functions are not
duplicated).
o Scalability for large compilation units was improved
significantly.
o Inlining of callbacks is now more aggressive.
o Virtual methods are considered for inlining when the
caller is inlined and devirtualization is then possible.
o Inlining when optimizing for size (either in cold regions
of a program or when compiling with -Os) was improved to
better handle C++ programs with larger abstraction
penalty, leading to smaller and faster code.
+ The IPA reference optimization pass detecting global variables
used or modified by functions was strengthened and sped up.
+ Functions whose address was taken are now optimized out when
all references to them are dead.
+ A new inter-procedural static profile estimation pass detects
functions that are executed once or unlikely to be executed.
Unlikely executed functions are optimized for size. Functions
executed once are optimized for size except for the inner
loops.
+ On most targets with named section support, functions used
only at startup (static constructors and main), functions used
only at exit and functions detected to be cold are placed into
separate text segment subsections. This extends the
-freorder-functions feature and is controlled by the same
switch. The goal is to improve the startup time of large C++
programs.
Proper function placement requires linker support. GNU ld
2.21.51 on ELF targets was updated to place those functions
together within the text section leading to better code
locality and faster startup times of large C++ programs. The
feature is also supported in the Apple linker. Support in the
gold linker is planned.
* A new switch -fstack-usage has been added. It makes the compiler
output stack usage information for the program, on a per-function
basis, in an auxiliary file.
* A new switch -fcombine-stack-adjustments has been added. It can be
used to enable or disable the compiler's stack-slot combining pass
which before was enabled automatically at -O1 and above, but could
not be controlled on its own.
* A new switch -fstrict-volatile-bitfields has been added. Using it
indicates that accesses to volatile bitfields should use a single
access of the width of the field's type. This option can be useful
for precisely defining and accessing memory-mapped peripheral
registers from C or C++.

Compile time and memory usage improvements

* Datastructures used by the dataflow framework in GCC were
reorganized for better memory usage and more cache locality.
Compile time is improved especially on units with large functions
(possibly resulting from a lot of inlining) not fitting into the
processor cache. The compile time of the GCC C compiler binary with
link-time optimization went down by over 10% (benchmarked on x86-64
target).

New Languages and Language specific improvements

Ada

* Stack checking has been improved on selected architectures (Alpha,
IA-32/x86-64, RS/6000 and SPARC): it now will detect stack
overflows in all cases on these architectures.
* Initial support for Ada 2012 has been added.

C family

* A new warning, enabled by -Wdouble-promotion, has been added that
warns about cases where a value of type float is implicitly
promoted to double. This is especially helpful for CPUs that handle
the former in hardware, but emulate the latter in software.
* A new function attribute leaf was introduced. This attribute allows
better inter-procedural optimization across calls to functions that
return to the current unit only via returning or exception
handling. This is the case for most library functions that have no
callbacks.
* Support for a new data type __int128 for targets having wide enough
machine-mode support.
* The new function attribute callee_pop_aggregate allows to specify
if the caller or callee is responsible for popping the aggregate
return pointer value from the stack.
* Support for selectively enabling and disabling warnings via #pragma
GCC diagnostic has been added. For instance:
#pragma GCC diagnostic error "-Wuninitialized"
foo(a); /* error is given for this one */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wuninitialized"
foo(b); /* no diagnostic for this one */
#pragma GCC diagnostic pop
foo(c); /* error is given for this one */
#pragma GCC diagnostic pop
foo(d); /* depends on command-line options */

* The -fmax-errors=N option is now supported. Using this option
causes the compiler to exit after N errors have been issued.

[7]C

* There is now experimental support for some features from the
upcoming C1X revision of the ISO C standard. This support may be
selected with -std=c1x, or -std=gnu1x for C1X with GNU extensions.
Note that this support is experimental and may change incompatibly
in future releases for consistency with changes to the C1X standard
draft. The following features are newly supported as described in
the N1539 draft of C1X (with changes agreed at the March 2011 WG14
meeting); some other features were already supported with no
compiler changes being needed, or have some support but not in full
accord with N1539 (as amended).
+ Static assertions (_Static_assert keyword)
+ Typedef redefinition
+ New macros in <float.h>
+ Anonymous structures and unions
* The new -fplan9-extensions option directs the compiler to support
some extensions for anonymous struct fields which are implemented
by the Plan 9 compiler. A pointer to a struct may be automatically
converted to a pointer to an anonymous field when calling a
function, in order to make the types match. An anonymous struct
field whose type is a typedef name may be referred to using the
typedef name.

[8]C++

* Improved [9]experimental support for the upcoming C++0x ISO C++
standard, including support for constexpr (thanks to Gabriel Dos
Reis and Jason Merrill), nullptr (thanks to Magnus Fromreide),
noexcept, unrestricted unions, range-based for loops (thanks to
Rodrigo Rivas Costa), opaque enum declarations (thanks also to
Rodrigo), implicitly deleted functions and implicit move
constructors.
* When an extern declaration within a function does not match a
declaration in the enclosing context, G++ now properly declares the
name within the namespace of the function rather than the namespace
which was open just before the function definition ([10]c++/43145).
* GCC now warns by default when casting integers to larger pointer
types. These warnings can be disabled with the option
-Wno-int-to-pointer-cast, which is now also available in C++.
* G++ no longer optimizes using the assumption that a value of
enumeration type will fall within the range specified by the
standard, since that assumption is easily violated with a
conversion from integer type ([11]c++/43680). The old behavior can
be restored with -fstrict-enums.
* The new -fnothrow-opt flag changes the semantics of a throw()
exception specification to match the proposed semantics of the
noexcept specification: just call terminate if an exception tries
to propagate out of a function with such an exception
specification. This dramatically reduces or eliminates the code
size overhead from adding the exception specification.
* The new -Wnoexcept flag will suggest adding a noexcept qualifier to
a function that the compiler can tell doesn't throw if it would
change the value of a noexcept expression.
* The -Wshadow option now warns if a local variable or type
declaration shadows another type in C++. Note that the compiler
will not warn if a local variable shadows a struct/class/enum, but
will warn if it shadows an explicit typedef.
* When an identifier is not found in the current scope, G++ now
offers suggestions about which identifier might have been intended.
* G++ now issues clearer diagnostics for missing semicolons after
class, struct, and union definitions.
* G++ now issues clearer diagnostics for missing semicolons after
class member declarations.
* G++ now issues clearer diagnostics when a colon is used in a place
where a double-colon was intended.
* G++ no longer accepts mutable on reference members ([12]c++/33558).
Use -fpermissive to allow the old, non-conforming behaviour.
* A few mangling fixes have been made, to attribute const/volatile on
function pointer types, decltype of a plain decl, and use of a
function parameter in the declaration of another parameter. By
default the compiler still uses the old mangling, but emits aliases
with the new mangling on targets that support strong aliases. Users
can switch over entirely to the new mangling with -fabi-version=5
or -fabi-version=0. -Wabi will now warn about code that uses the
old mangling.
* In 4.6.0 and 4.6.1 G++ no longer allows objects of const-qualified
type to be default initialized unless the type has a user-declared
default constructor. In 4.6.2 G++ implements the proposed
resolution of [13]DR 253, so default initialization is allowed if
it initializes all subobjects. Code that fails to compile can be
fixed by providing an initializer e.g.
struct A { A(); };
struct B : A { int i; };
const B b = B();
Use -fpermissive to allow the old, non-conforming behaviour.

Runtime Library (libstdc++)

* [14]Improved experimental support for the upcoming ISO C++
standard, C++0x, including using constexpr and nullptr.
* Performance improvements to the [15]Debug Mode, thanks to Fran�ois
Dumont.
* Atomic operations used for reference-counting are annotated so that
they can be understood by race detectors such as Helgrind, see
[16]Data Race Hunting.
* Most libstdc++ standard headers have been changed to no longer
include the cstddef header as an implementation detail. Code that
relied on that header being included as side-effect of including
other standard headers will need to include cstddef explicitly.

[17]Fortran

* On systems supporting the libquadmath library, GNU Fortran now also
supports a quad-precision, kind=16 floating-point data type
(REAL(16), COMPLEX(16)). As the data type is not fully supported in
hardware, calculations might be one to two orders of magnitude
slower than with the 4, 8 or 10 bytes floating-point data types.
This change does not affect systems which support REAL(16) in
hardware nor those which do not support libquadmath.
* Much improved compile time for large array constructors.
* In order to reduce execution time and memory consumption, use of
temporary arrays in assignment expressions is avoided for many
cases. The compiler now reverses loops in order to avoid generating
a temporary array where possible.
* Improved diagnostics, especially with -fwhole-file.
* The -fwhole-file flag is now enabled by default. This improves code
generation and diagnostics. It can be disabled using the deprecated
-fno-whole-file flag.
* Support the generation of Makefile dependencies via the [18]-M...
flags of GCC; you may need to specify the -cpp option in addition.
The dependencies take modules, Fortran's include, and CPP's
#include into account. Note: Using -M for the module path is no
longer supported, use -J instead.
* The flag -Wconversion has been modified to only issue warnings
where a conversion leads to information loss. This drastically
reduces the number of warnings; -Wconversion is thus now enabled
with -Wall. The flag -Wconversion-extra has been added and also
warns about other conversions; -Wconversion-extra typically issues
a huge number of warnings, most of which can be ignored.
* A new command-line option -Wunused-dummy-argument warns about
unused dummy arguments and is included in -Wall. Before,
-Wunused-variable also warned about unused dummy arguments.
* Fortran 2003 support has been extended:
+ Improved support for polymorphism between libraries and
programs and for complicated inheritance patterns (cf.
[19]object-oriented programming).
+ Experimental support of the ASSOCIATE construct.
+ In pointer assignments it is now possible to specify the lower
bounds of the pointer and, for a rank-1 or a simply contiguous
data-target, to remap the bounds.
+ Automatic (re)allocation: In intrinsic assignments to
allocatable variables the left-hand side will be automatically
allocated (if unallocated) or reallocated (if the shape or
type parameter is different). To avoid the small performance
penalty, you can use a(:) = ... instead of a = ... for arrays
and character strings - or disable the feature using -std=f95
or -fno-realloc-lhs.
+ Deferred type parameter: For scalar allocatable and pointer
variables the character length can be deferred.
+ Namelist variables with allocatable and pointer attribute and
nonconstant length type parameter are supported.
* Fortran 2008 support has been extended:
+ Experimental [20]coarray support (for one image only, i.e.
num_images() == 1); use the [21]-fcoarray=single flag to
enable it.
+ The STOP and the new ERROR STOP statements now support all
constant expressions.
+ Support for the CONTIGUOUS attribute.
+ Support for ALLOCATE with MOLD.
+ Support for the STORAGE_SIZE intrinsic inquiry function.
+ Support of the NORM2 and PARITY intrinsic functions.
+ The following bit intrinsics were added: POPCNT and POPPAR for
counting the number of 1 bits and returning the parity; BGE,
BGT, BLE, and BLT for bitwise comparisons; DSHIFTL and DSHIFTR
for combined left and right shifts, MASKL and MASKR for simple
left and right justified masks, MERGE_BITS for a bitwise merge
using a mask, SHIFTA, SHIFTL and SHIFTR for shift operations,
and the transformational bit intrinsics IALL, IANY and
IPARITY.
+ Support of the EXECUTE_COMMAND_LINE intrinsic subroutine.
+ Support for the IMPURE attribute for procedures, which allows
for ELEMENTAL procedures without the restrictions of PURE.
+ Null pointers (including NULL()) and not allocated variables
can be used as actual argument to optional non-pointer,
non-allocatable dummy arguments, denoting an absent argument.
+ Non-pointer variables with TARGET attribute can be used as
actual argument to POINTER dummies with INTENT(IN)
+ Pointers including procedure pointers and those in a derived
type (pointer components) can now be initialized by a target
instead of only by NULL.
+ The EXIT statement (with construct-name) can now be used to
leave not only the DO but also the ASSOCIATE, BLOCK, IF,
SELECT CASE and SELECT TYPE constructs.
+ Internal procedures can now be used as actual argument.
+ The named constants INTEGER_KINDS, LOGICAL_KINDS, REAL_KINDS
and CHARACTER_KINDS of the intrinsic module ISO_FORTRAN_ENV
have been added; these arrays contain the supported kind
values for the respective types.
+ The module procedures C_SIZEOF of the intrinsic module
ISO_C_BINDINGS and COMPILER_VERSION and COMPILER_OPTIONS of
ISO_FORTRAN_ENV have been implemented.
+ Minor changes: obsolescence diagnostics for ENTRY was added
for -std=f2008; a line may start with a semicolon; for
internal and module procedures END can be used instead of END
SUBROUTINE and END FUNCTION; SELECTED_REAL_KIND now also takes
a RADIX argument; intrinsic types are supported for
TYPE(intrinsic-type-spec); multiple type-bound procedures can
be declared in a single PROCEDURE statement; implied-shape
arrays are supported for named constants (PARAMETER). The
transformational, three argument versions of BESSEL_JN and
BESSEL_YN were added - the elemental, two-argument version had
been added in GCC 4.4; note that the transformational
functions use a recurrence algorithm.

[22]Go

Support for the Go programming language has been added to GCC. It is
not enabled by default when you build GCC; use the --enable-languages
configure option to build it. The driver program for compiling Go code
is gccgo.

Go is currently known to work on GNU/Linux and RTEMS. Solaris support
is in progress. It may or may not work on other platforms.

[23]Objective-C and Objective-C++

* The -fobjc-exceptions flag is now required to enable Objective-C
exception and synchronization syntax (introduced by the keywords
@try, @catch, @finally and @synchronized).
* A number of Objective-C 2.0 features and extensions are now
supported by GCC. These features are enabled by default; you can
disable them by using the new -fobjc-std=objc1 command-line option.
* The Objective-C 2.0 dot-syntax is now supported. It is an
alternative syntax for using getters and setters; object.count is
automatically converted into [object count] or [object setCount:
...] depending on context; for example if (object.count > 0) is
automatically compiled into the equivalent of if ([object count] >
0) while object.count = 0; is automatically compiled into the
equivalent ot [object setCount: 0];. The dot-syntax can be used
with instance and class objects and with any setters or getters, no
matter if they are part of a declared property or not.
* Objective-C 2.0 declared properties are now supported. They are
declared using the new @property keyword, and are most commonly
used in conjunction with the new Objective-C 2.0 dot-syntax. The
nonatomic, readonly, readwrite, assign, retain, copy, setter and
getter attributes are all supported. Marking declared properties
with __attribute__ ((deprecated)) is supported too.
* The Objective-C 2.0 @synthesize and @dynamic keywords are
supported. @synthesize causes the compiler to automatically
synthesize a declared property, while @dynamic is used to disable
all warnings for a declared property for which no implementation is
provided at compile time. Synthesizing declared properties requires
runtime support in most useful cases; to be able to use it with the
GNU runtime, appropriate helper functions have been added to the
GNU Objective-C runtime ABI, and are implemented by the GNU
Objective-C runtime library shipped with GCC.
* The Objective-C 2.0 fast enumeration syntax is supported in
Objective-C. This is currently not yet available in Objective-C++.
Fast enumeration requires support in the runtime, and such support
has been added to the GNU Objective-C runtime library (shipped with
GCC).
* The Objective-C 2.0 @optional keyword is supported. It allows you
to mark methods or properties in a protocol as optional as opposed
to required.
* The Objective-C 2.0 @package keyword is supported. It has currently
the same effect as the @public keyword.
* Objective-C 2.0 method attributes are supported. Currently the
supported attributes are deprecated, sentinel, noreturn and format.
* Objective-C 2.0 method argument attributes are supported. The most
widely used attribute is unused, to mark an argument as unused in
the implementation.
* Objective-C 2.0 class and protocol attributes are supported.
Currently the only supported attribute is deprecated.
* Objective-C 2.0 class extensions are supported. A class extension
has the same syntax as a category declaration with no category
name, and the methods and properties declared in it are added
directly to the main class. It is mostly used as an alternative to
a category to add methods to a class without advertising them in
the public headers, with the advantage that for class extensions
the compiler checks that all the privately declared methods are
actually implemented.
* As a result of these enhancements, GCC can now be used to build
Objective-C and Objective-C++ software that uses Foundation and
other important system frameworks with the NeXT runtime on Darwin 9
and Darwin 10 (OSX 10.5 and 10.6).
* Many bugs in the compiler have been fixed in this release; in
particular, LTO can now be used when compiling Objective-C and
Objective-C++ and the parser is much more robust in dealing with
invalid code.

Runtime Library (libobjc)

* The GNU Objective-C runtime library now defines the macro
__GNU_LIBOBJC__ (with a value that is increased at every release
where there is any change to the API) in objc/objc.h, making it
easy to determine if the GNU Objective-C runtime library is being
used, and if so, which version. Previous versions of the GNU
Objective-C runtime library (and other Objective-C runtime
libraries such as the Apple one) do not define this macro.
* A new Objective-C 2.0 API, almost identical to the one implemented
by the Apple Objective-C runtime, has been implemented in the GNU
Objective-C runtime library. The new API hides the internals of
most runtime structures but provides a more extensive set of
functions to operate on them. It is much easier, for example, to
create or modify classes at runtime. The new API also makes it
easier to port software from Apple to GNU as almost no changes
should be required. The old API is still supported for backwards
compatibility; including the old objc/objc-api.h header file
automatically selects the old API, while including the new
objc/runtime.h header file automatically selects the new API.
Support for the old API is being phased out and upgrading the
software to use the new API is strongly recommended. To check for
the availability of the new API, the __GNU_LIBOBJC__ macro can be
used as older versions of the GNU Objective-C runtime library,
which do not support the new API, do not define such a macro.
* Runtime support for @synchronized has been added.
* Runtime support for Objective-C 2.0 synthesized property accessors
has been added.
* Runtime support for Objective-C 2.0 fast enumeration has been
added.

[24]New Targets and Target Specific Improvements

[25]ARM

* GCC now supports the Cortex-M4 processor implementing the v7-em
version of the architecture using the option -mcpu=cortex-m4.
* Scheduling descriptions for the Cortex-M4, the Neon and the
floating point units of the Cortex-A9 and a pipeline description
for the Cortex-A5 have been added.
* Synchronization primitives such as __sync_fetch_and_add and friends
are now inlined for supported architectures rather than calling
into a kernel helper function.
* SSA loop prefetching is enabled by default for the Cortex-A9 at
-O3.
* Several improvements were committed to improve code generation for
the ARM architecture including a rewritten implementation for load
and store multiples.
* Several enhancements were committed to improve SIMD code generation
for NEON by adding support for widening instructions, misaligned
loads and stores, vector conditionals and support for 64-bit
arithmetic.
* Support was added for the Faraday cores fa526, fa606te, fa626te,
fmp626te, fmp626 and fa726te and can be used with the respective
names as parameters to the -mcpu= option.
* Basic support was added for Cortex-A15 and is available through
-mcpu=cortex-a15.
* GCC for AAPCS configurations now more closely adheres to the AAPCS
specification by enabling -fstrict-volatile-bitfields by default.

IA-32/x86-64

* The new -fsplit-stack option permits programs to use a
discontiguous stack. This is useful for threaded programs, in that
it is no longer necessary to specify the maximum stack size when
creating a thread. This feature is currently only implemented for
32-bit and 64-bit x86 GNU/Linux targets.
* Support for emitting profiler counter calls before function
prologues. This is enabled via a new command-line option -mfentry.
* Optimization for the Intel Core 2 processors is now available
through the -march=core2 and -mtune=core2 options.
* Support for Intel Core i3/i5/i7 processors is now available through
the -march=corei7 and -mtune=corei7 options.
* Support for Intel Core i3/i5/i7 processors with AVX is now
available through the -march=corei7-avx and -mtune=corei7-avx
options.
* Support for AMD Bobcat (family 14) processors is now available
through the -march=btver1 and -mtune=btver1 options.
* Support for AMD Bulldozer (family 15) processors is now available
through the -march=bdver1 and -mtune=bdver1 options.
* The default setting (when not optimizing for size) for 32-bit
GNU/Linux and Darwin x86 targets has been changed to
-fomit-frame-pointer. The default can be reverted to
-fno-omit-frame-pointer by configuring GCC with the
--enable-frame-pointer configure option.
* Darwin, FreeBSD, Solaris 2, MinGW and Cygwin now all support
__float128 on 32-bit and 64-bit x86 targets.
* AVX floating-point arithmetic can now be enabled by default at
configure time with the new --with-fpmath=avx option.
* The SSA loop prefetching pass is enabled when using -O3 when
optimizing for CPUs where prefetching is beneficial (AMD CPUs newer
than K6).
* Support for TBM (Trailing Bit Manipulation) built-in functions and
code generation is available via -mtbm.
* Support for AMD's BMI (Bit Manipulation) built-in functions and
code generation is available via -mbmi.

[26]MicroBlaze

* Support has been added for the Xilinx MicroBlaze softcore processor
(microblaze-elf) embedded target. This configurable processor is
supported on several Xilinx Spartan and Virtex FPGAs.

MIPS

* GCC now supports the Loongson 3A processor. Its canonical -march=
and -mtune= name is loongson3a.

[27]MN10300 / AM33

* The inline assembly register constraint "A" has been renamed "c".
This constraint is used to select a floating-point register that
can be used as the destination of a multiply-accumulate
instruction.
* New inline assembly register constraints "A" and "D" have been
added. These constraint letters resolve to all general registers
when compiling for AM33, and resolve to address registers only or
data registers only when compiling for MN10300.
* The MDR register is represented in the compiler. One can access the
register via the "z" constraint in inline assembly. It can be
marked as clobbered or used as a local register variable via the
"mdr" name. The compiler uses the RETF instruction if the function
does not modify the MDR register, so it is important that inline
assembly properly annotate any usage of the register.

PowerPC/PowerPC64

* GCC now supports the Applied Micro Titan processor with
-mcpu=titan.
* The -mrecip option has been added, which indicates whether the
reciprocal and reciprocal square root instructions should be used.
* The -mveclibabi=mass option can be used to enable the compiler to
autovectorize mathematical functions using the Mathematical
Acceleration Subsystem library.
* The -msingle-pic-base option has been added, which instructs the
compiler to avoid loading the PIC base register in function
prologues. The PIC base register must be initialized by the runtime
system.
* The -mblock-move-inline-limit option has been added, which enables
the user to control the maximum size of inlined memcpy calls and
similar.
* PowerPC64 GNU/Linux support for applications requiring a large TOC
section has been improved. A new command-line option,
-mcmodel=MODEL, controls this feature; valid values for MODEL are
small, medium, or large.
* The Altivec builtin functions vec_ld and vec_st have been modified
to generate the Altivec memory instructions LVX and STVX, even if
the -mvsx option is used. In the initial GCC 4.5 release, these
builtin functions were changed to generate VSX memory reference
instructions instead of Altivec memory instructions, but there are
differences between the two instructions. If the VSX instruction
set is available, you can now use the new builtin functions
vec_vsx_ld and vec_vsx_st which always generates the VSX memory
instructions.
* The GCC compiler on AIX now defaults to a process layout with a
larger data space allowing larger programs to be compiled.
* The GCC long double type on AIX 6.1 and above has reverted to
64-bit double precision, matching the AIX XL compiler default,
because of missing C99 symbols required by the GCC runtime.
* The default processor scheduling model and tuning for PowerPC64
GNU/Linux and for AIX 6.1 and above now is POWER7.
* Starting with GCC 4.6.1, vectors of type vector long long or vector
long are passed and returned in the same method as other vectors
with the VSX instruction set. Previously the GCC compiler did not
adhere to the ABI for 128-bit vectors with 64-bit integer base
types (PR 48857). This is also fixed in the GCC 4.5.4 release.

S/390, zSeries and System z9/z10, IBM zEnterprise z196

* Support for the zEnterprise z196 processor has been added. When
using the -march=z196 option, the compiler will generate code
making use of the following instruction facilities:
+ Conditional load/store
+ Distinct-operands
+ Floating-point-extension
+ Interlocked-access
+ Population-count
The -mtune=z196 option avoids the compare and branch instructions
as well as the load address instruction with an index register as
much as possible and performs instruction scheduling appropriate
for the new out-of-order pipeline architecture.
* When using the -m31 -mzarch options the generated code still
conforms to the 32-bit ABI but uses the general purpose registers
as 64-bit registers internally. This requires a Linux kernel saving
the whole 64-bit registers when doing a context switch. Kernels
providing that feature indicate that by the 'highgprs' string in
/proc/cpuinfo.
* The SSA loop prefetching pass is enabled when using -O3.

SPARC

* GCC now supports the LEON series of SPARC V8 processors. The code
generated by the compiler can either be tuned to it by means of the
--with-tune=leon configure option and -mtune=leon compilation
option, or the compiler can be built for the sparc-leon-{elf,linux}
and sparc-leon3-{elf,linux} targets directly.
* GCC has stopped sign/zero-extending parameter registers in the
callee for functions taking parameters with sub-word size in 32-bit
mode, since this is redundant with the specification of the ABI.
GCC has never done so in 64-bit mode since this is also redundant.
* The command-line option -mfix-at697f has been added to enable the
documented workaround for the single erratum of the Atmel AT697F
processor.

[28]Operating Systems

[29]Android

* GCC now supports the Bionic C library and provides a convenient way
of building native libraries and applications for the Android
platform. Refer to the documentation of the -mandroid and -mbionic
options for details on building native code. At the moment, Android
support is enabled only for ARM.

[30]Darwin/Mac OS X

* General
+ Initial support for CFString types has been added.
This allows GCC to build projects including the system Core
Foundation frameworks. The GCC Objective-C family supports
CFString "toll-free bridged" as per the Mac OS X system tools.
CFString is also recognized in the context of format
attributes and arguments (see the documentation for format
attributes for limitations). At present, 8-bit character types
are supported.
+ Object file size reduction.
The Darwin zeroed memory allocators have been re-written to
make more use of .zerofill sections. For non-debug code, this
can reduce object file size significantly.
+ Objective-C family 64-bit support (NeXT ABI 2).
Initial support has been added to support 64-bit Objective-C
code using the Darwin/OS X native (NeXT) runtime. ABI version
2 will be selected automatically when 64-bit code is built.
+ Objective-C family 32-bit ABI 1.
For 32-bit code ABI 1 is also now also allowed. At present it
must be selected manually using -fobjc-abi-version=1 where
applicable - i.e. on Darwin 9/10 (OS X 10.5/10.6).
* x86 Architecture
+ The -mdynamic-no-pic option has been enabled.
Code supporting -mdynamic-no-pic optimization has been added
and is applicable to -m32 builds. The compiler bootstrap uses
the option where appropriate.
+ The default value for -mtune= has been changed.
Since Darwin systems are primarily Xeon, Core-2 or similar the
default tuning has been changed to -mtune=core2.
+ Enable 128-bit long double (__float128) support on Darwin.
* PPC Architecture
+ Darwin64 ABI.
Several significant bugs have been fixed, such that GCC now
produces code compatible with the Darwin64 PowerPC ABI.
+ libffi and boehm-gc.
The Darwin ports of the libffi and boehm-gc libraries have
been upgraded to include a Darwin64 implementation. This means
that powerpc*-*-darwin9 platforms may now, for example, build
Java applications with -m64 enabled.
+ Plug-in support has been enabled.
+ The -fsection-anchors option is now available although,
presently, not heavily tested.

[31]Solaris 2

New Features

* Support symbol versioning with the Sun linker.
* Allow libstdc++ to leverage full ISO C99 support on Solaris 10+.
* Support thread-local storage (TLS) with the Sun assembler on
Solaris 2/x86.
* Support TLS on Solaris 8/9 if prerequisites are met.
* Support COMDAT group with the GNU assembler and recent Sun linker.
* Support the Sun assembler visibility syntax.
* Default Solaris 2/x86 to -march=pentium4 (Solaris 10+) resp.
-march=pentiumpro (Solaris 8/9).
* Don't use SSE on Solaris 8/9 x86 by default.
* Enable 128-bit long double (__float128) support on Solaris 2/x86.

ABI Change

* Change the ABI for returning 8-byte vectors like __m64 in MMX
registers on Solaris 10+/x86 to match the Sun Studio 12.1+
compilers. This is an incompatible change. If you use such types,
you must either recompile all your code with the new compiler or
use the new -mvect8-ret-in-mem option to remain compatible with
previous versions of GCC and Sun Studio.

[32]Windows x86/x86_64

* Initial support for decimal floating point.
* Support for the __thiscall calling-convention.
* Support for hot-patchable function prologues via the
ms_hook_prologue attribute for x86_64 in addition to 32-bit x86.
* Improvements of stack-probing and stack-allocation mechanisms.
* Support of push/pop-macro pragma as preprocessor command.
With #pragma push_macro("macro-name") the current definition of
macro-name is saved and can be restored with #pragma
pop_macro("macro-name") to its saved definition.
* Enable 128-bit long double (__float128) support on MinGW and
Cygwin.

Other significant improvements

Installation changes

* An install-strip make target is provided that installs stripped
executables, and may install libraries with unneeded or debugging
sections stripped.
* On Power7 systems, there is a potential problem if you build the
GCC compiler with a host compiler using options that enable the VSX
instruction set generation. If the host compiler has been patched
so that the vec_ld and vec_st builtin functions generate Altivec
memory instructions instead of VSX memory instructions, then you
should be able to build the compiler with VSX instruction
generation.

Changes for GCC Developers

Note: these changes concern developers that develop GCC itself or
software that integrates with GCC, such as plugins, and not the general
GCC users.
* The gengtype utility, which previously was internal to the GCC
build process, has been enchanced to provide GC root information
for plugins as necessary.
* The old GC allocation interface of ggc_alloc and friends was
replaced with a type-safe alternative.

[33]GCC 4.6.1

This is the [34]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.6.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[35]GCC 4.6.2

This is the [36]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.6.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[37]GCC 4.6.3

This is the [38]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.6.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[39]GCC 4.6.4

This is the [40]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.6.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

For questions related to the use of GCC, please consult these web
pages and the [41]GCC manuals. If that fails, the
[42][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [43][email protected]. All of [44]our lists have public
archives.

Copyright (C) [45]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [46]maintained by the GCC team. Last modified
2025-01-31.

References

1. https://sourceware.org/bugzilla/show_bug.cgi?id=10401
2. https://gcc.gnu.org/gcc-4.5/changes.html
3. https://gcc.gnu.org/gcc-4.5/changes.html#obsoleted
4. https://gcc.gnu.org/gcc-4.6/porting_to.html
5. https://gcc.gnu.org/projects/lto/whopr.pdf
6. https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#Warning-Options
7. https://gcc.gnu.org/gcc-4.6/changes.html#c
8. https://gcc.gnu.org/gcc-4.6/changes.html#cplusplus
9. https://gcc.gnu.org/gcc-4.6/cxx0x_status.html
10. https://gcc.gnu.org/PR43145
11. https://gcc.gnu.org/PR43680
12. https://gcc.gnu.org/PR33558
13. https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#253
14. https://gcc.gnu.org/onlinedocs/gcc-4.6.4/libstdc++/manual/manual/status.html#status.iso.200x
15. https://gcc.gnu.org/onlinedocs/libstdc++/manual/debug_mode.html
16. https://gcc.gnu.org/onlinedocs/libstdc++/manual/debug.html#debug.races
17. https://gcc.gnu.org/gcc-4.6/changes.html#fortran
18. https://gcc.gnu.org/onlinedocs/gcc/Preprocessor-Options.html
19. https://gcc.gnu.org/wiki/OOP
20. https://gcc.gnu.org/wiki/Coarray
21. https://gcc.gnu.org/onlinedocs/gfortran/Code-Gen-Options.html#index-g_t_0040code_007bfcoarray_007d-233
22. https://gcc.gnu.org/gcc-4.6/changes.html#go
23. https://gcc.gnu.org/gcc-4.6/changes.html#objective-c
24. https://gcc.gnu.org/gcc-4.6/changes.html#targets
25. https://gcc.gnu.org/gcc-4.6/changes.html#arm
26. https://gcc.gnu.org/gcc-4.6/changes.html#microblaze
27. https://gcc.gnu.org/gcc-4.6/changes.html#mn10300
28. https://gcc.gnu.org/gcc-4.6/changes.html#os
29. https://gcc.gnu.org/gcc-4.6/changes.html#android
30. https://gcc.gnu.org/gcc-4.6/changes.html#darwin
31. https://gcc.gnu.org/gcc-4.6/changes.html#solaris
32. https://gcc.gnu.org/gcc-4.6/changes.html#windows
33. https://gcc.gnu.org/gcc-4.6/changes.html#GCC4.6.1
34. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.6.1
35. https://gcc.gnu.org/gcc-4.6/changes.html#GCC4.6.2
36. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.6.2
37. https://gcc.gnu.org/gcc-4.6/changes.html#GCC4.6.3
38. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.6.3
39. https://gcc.gnu.org/gcc-4.6/changes.html#GCC4.6.4
40. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.6.4
41. https://gcc.gnu.org/onlinedocs/
42. mailto:[email protected]
43. mailto:[email protected]
44. https://gcc.gnu.org/lists.html
45. https://www.fsf.org/
46. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.5/index.html

GCC 4.5 Release Series

(This release series is no longer supported.)

Jul 2, 2012

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 4.5.4.

This release is a bug-fix release, containing fixes for regressions in
GCC 4.5.3 relative to previous releases of GCC.

Release History

GCC 4.5.4
Jul 2, 2012 ([2]changes)

GCC 4.5.3
Apr 28, 2011 ([3]changes)

GCC 4.5.2
Dec 16, 2010 ([4]changes)

GCC 4.5.1
Jul 31, 2010 ([5]changes)

GCC 4.5.0
April 14, 2010 ([6]changes)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [7]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [8]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [9]GCC project
web site or contact the [10]GCC development mailing list.

To obtain GCC please use [11]our mirror sites or [12]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [13]GCC manuals. If that fails, the
[14][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [15][email protected]. All of [16]our lists have public
archives.

Copyright (C) [17]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [18]maintained by the GCC team. Last modified
2022-10-26.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-4.5/changes.html
3. https://gcc.gnu.org/gcc-4.5/changes.html
4. https://gcc.gnu.org/gcc-4.5/changes.html
5. https://gcc.gnu.org/gcc-4.5/changes.html
6. https://gcc.gnu.org/gcc-4.5/changes.html
7. https://gcc.gnu.org/gcc-4.5/buildstat.html
8. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
9. https://gcc.gnu.org/index.html
10. mailto:[email protected]
11. https://gcc.gnu.org/mirrors.html
12. https://gcc.gnu.org/git.html
13. https://gcc.gnu.org/onlinedocs/
14. mailto:[email protected]
15. mailto:[email protected]
16. https://gcc.gnu.org/lists.html
17. https://www.fsf.org/
18. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.5/changes.html

GCC 4.5 Release Series
Changes, New Features, and Fixes

Caveats

* GCC now requires the [1]MPC library in order to build. See the
[2]prerequisites page for version requirements.
* Support for a number of older systems and recently unmaintained or
untested target ports of GCC has been declared obsolete in GCC 4.5.
Unless there is activity to revive them, the next release of GCC
will have their sources permanently removed.
The following ports for individual systems on particular
architectures have been obsoleted:
+ IRIX releases before 6.5 (mips-sgi-irix5*,
mips-sgi-irix6.[0-4])
+ Solaris 7 (*-*-solaris2.7)
+ Tru64 UNIX releases before V5.1 (alpha*-dec-osf4*,
alpha-dec-osf5.0*)
+ Details for the IRIX, Solaris 7, and Tru64 UNIX obsoletions
can be found in the [3]announcement.
Support for the classic POWER architecture implemented in the
original RIOS and RIOS2 processors of the old IBM RS/6000 product
line has been obsoleted in the rs6000 port. This does not affect
the new generation Power and PowerPC architectures.
* Support has been removed for all the [4]configurations obsoleted in
GCC 4.4.
* Support has been removed for the protoize and unprotoize utilities,
obsoleted in GCC 4.4.
* Support has been removed for tuning for Itanium1 (Merced) variants.
Note that code tuned for Itanium2 should also run correctly on
Itanium1.
* GCC now generates unwind info also for epilogues. DWARF debuginfo
generated by GCC now uses more features of DWARF3 than before, and
also some DWARF4 features. GDB older than 7.0 is not able to handle
either of these, so to debug GCC 4.5 generated binaries or
libraries GDB 7.0 or later is needed. You can disable use of DWARF4
features with the -gdwarf-3 -gstrict-dwarf options, or use
-gdwarf-2 -gstrict-dwarf to restrict GCC to just DWARF2, but
epilogue unwind info is emitted unconditionally whenever unwind
info is emitted.
* On x86 targets, code containing floating-point calculations may run
significantly more slowly when compiled with GCC 4.5 in strict C99
conformance mode than they did with earlier GCC versions. This is
due to stricter standard conformance of the compiler and can be
avoided by using the option -fexcess-precision=fast; also see
[5]below.
* The function attribute noinline no longer prevents GCC from cloning
the function. A new attribute noclone has been introduced for this
purpose. Cloning a function means that it is duplicated and the new
copy is specialized for certain contexts (for example when a
parameter is a known constant).

General Optimizer Improvements

* The -save-temps now takes an optional argument. The -save-temps and
-save-temps=cwd switches write the temporary files in the current
working directory based on the original source file. The
-save-temps=obj switch will write files into the directory
specified with the -o option, and the intermediate filenames are
based on the output file. This will allow the user to get the
compiler intermediate files when doing parallel builds without two
builds of the same filename located in different directories from
interfering with each other.
* Debugging dumps are now created in the same directory as the object
file rather than in the current working directory. This allows the
user to get debugging dumps when doing parallel builds without two
builds of the same filename interfering with each other.
* GCC has been integrated with the MPC library. This allows GCC to
evaluate complex arithmetic at compile time [6]more accurately. It
also allows GCC to evaluate calls to complex built-in math
functions having constant arguments and replace them at compile
time with their mathematically equivalent results. In doing so, GCC
can generate correct results regardless of the math library
implementation or floating point precision of the host platform.
This also allows GCC to generate identical results regardless of
whether one compiles in native or cross-compile configurations to a
particular target. The following built-in functions take advantage
of this new capability: cacos, cacosh, casin, casinh, catan,
catanh, ccos, ccosh, cexp, clog, cpow, csin, csinh, csqrt, ctan,
and ctanh. The float and long double variants of these functions
(e.g. csinf and csinl) are also handled.
* A new link-time optimizer has been added ([7]-flto). When this
option is used, GCC generates a bytecode representation of each
input file and writes it to specially-named sections in each object
file. When the object files are linked together, all the function
bodies are read from these named sections and instantiated as if
they had been part of the same translation unit. This enables
interprocedural optimizations to work across different files (and
even different languages), potentially improving the performance of
the generated code. To use the link-timer optimizer, -flto needs to
be specified at compile time and during the final link. If the
program does not require any symbols to be exported, it is possible
to combine -flto and the experimental [8]-fwhopr with
[9]-fwhole-program to allow the interprocedural optimizers to use
more aggressive assumptions.
* The automatic parallelization pass was enhanced to support
parallelization of outer loops.
* Automatic parallelization can be enabled as part of Graphite. In
addition to -ftree-parallelize-loops=, specify
-floop-parallelize-all to enable the Graphite-based optimization.
* The infrastructure for optimizing based on [10]restrict qualified
pointers has been rewritten and should result in code generation
improvements. Optimizations based on restrict qualified pointers
are now also available when using -fno-strict-aliasing.
* There is a new optimization pass that attempts to change prototype
of functions to avoid unused parameters, pass only relevant parts
of structures and turn arguments passed by reference to arguments
passed by value when possible. It is enabled by -O2 and above as
well as -Os and can be manually invoked using the new command-line
switch -fipa-sra.
* GCC now optimize exception handling code. In particular cleanup
regions that are proved to not have any effect are optimized out.

New Languages and Language specific improvements

All languages

* The -fshow-column option is now on by default. This means error
messages now have a column associated with them.

Ada

* Compilation of programs heavily using discriminated record types
with variant parts has been sped up and generates more compact
code.
* Stack checking now works reasonably well on most plaforms. In some
specific cases, stack overflows may still fail to be detected, but
a compile-time warning will be issued for these cases.

C family

* If a header named in a #include directive is not found, the
compiler exits immediately. This avoids a cascade of errors arising
from declarations expected to be found in that header being
missing.
* A new built-in function __builtin_unreachable() has been added that
tells the compiler that control will never reach that point. It may
be used after asm statements that terminate by transferring control
elsewhere, and in other places that are known to be unreachable.
* The -Wlogical-op option now warns for logical expressions such as
(c == 1 && c == 2) and (c != 1 || c != 2), which are likely to be
mistakes. This option is disabled by default.
* An asm goto feature has been added to allow asm statements that
jump to C labels.
* C++0x raw strings are supported for C++ and for C with -std=gnu99.
* The deprecated attribute now takes an optional string argument, for
example, __attribute__((deprecated("text string"))), that will be
printed together with the deprecation warning.

C

* The -Wenum-compare option, which warns when comparing values of
different enum types, now works for C. It formerly only worked for
C++. This warning is enabled by -Wall. It may be avoided by using a
type cast.
* The -Wcast-qual option now warns about casts which are unsafe in
that they permit const-correctness to be violated without further
warnings. Specifically, it warns about cases where a qualifier is
added when all the lower types are not const. For example, it warns
about a cast from char ** to const char **.
* The -Wc++-compat option is significantly improved. It issues new
warnings for:
+ Using C++ reserved operator names as identifiers.
+ Conversions to enum types without explicit casts.
+ Using va_arg with an enum type.
+ Using different enum types in the two branches of ?:.
+ Using ++ or -- on a variable of enum type.
+ Using the same name as both a struct, union or enum tag and a
typedef, unless the typedef refers to the tagged type itself.
+ Using a struct, union, or enum which is defined within another
struct or union.
+ A struct field defined using a typedef if there is a field in
the struct, or an enclosing struct, whose name is the typedef
name.
+ Duplicate definitions at file scope.
+ Uninitialized const variables.
+ A global variable with an anonymous struct, union, or enum
type.
+ Using a string constant to initialize a char array whose size
is the length of the string.
* The new -Wjump-misses-init option warns about cases where a goto or
switch skips the initialization of a variable. This sort of branch
is an error in C++ but not in C. This warning is enabled by
-Wc++-compat.
* GCC now ensures that a C99-conforming <stdint.h> is present on most
targets, and uses information about the types in this header to
implement the Fortran bindings to those types. GCC does not ensure
the presence of such a header, and does not implement the Fortran
bindings, on the following targets: NetBSD, VxWorks, VMS,
SymbianOS, WinCE, LynxOS, Netware, QNX, Interix, TPF.
* GCC now implements C90- and C99-conforming rules for constant
expressions. This may cause warnings or errors for some code using
expressions that can be folded to a constant but are not constant
expressions as defined by ISO C.
* All known target-independent C90 and C90 Amendment 1 conformance
bugs, and all known target-independent C99 conformance bugs not
related to floating point or extended identifiers, have been fixed.
* The C decimal floating point support now includes support for the
FLOAT_CONST_DECIMAL64 pragma.
* The named address space feature from ISO/IEC TR 18037 is now
supported. This is currently only implemented for the SPU
processor.

[11]C++

* Improved [12]experimental support for the upcoming C++0x ISO C++
standard, including support for raw strings, lambda expressions and
explicit type conversion operators.
* When printing the name of a class template specialization, G++ will
now omit any template arguments which come from default template
arguments. This behavior (and the pretty-printing of function
template specializations as template signature and arguments) can
be disabled with the -fno-pretty-templates option.
* Access control is now applied to typedef names used in a template,
which may cause G++ to reject some ill-formed code that was
accepted by earlier releases. The -fno-access-control option can be
used as a temporary workaround until the code is corrected.
* Compilation time for code that uses templates should now scale
linearly with the number of instantiations rather than
quadratically, as template instantiations are now looked up using
hash tables.
* Declarations of functions that look like builtin declarations of
library functions are only considered to be redeclarations if they
are declared with extern "C". This may cause problems with code
that omits extern "C" on hand-written declarations of C library
functions such as abort or memcpy. Such code is ill-formed, but was
accepted by earlier releases.
* Diagnostics that used to complain about passing non-POD types to
... or jumping past the declaration of a non-POD variable now check
for triviality rather than PODness, as per C++0x.
* In C++0x mode local and anonymous classes are now allowed as
template arguments, and in declarations of variables and functions
with linkage, so long as any such declaration that is used is also
defined ([13]DR 757).
* Labels may now have attributes, as has been permitted for a while
in C. This is only permitted when the label definition and the
attribute specifier is followed by a semicolon--i.e., the label
applies to an empty statement. The only useful attribute for a
label is unused.
* G++ now implements [14]DR 176. Previously G++ did not support using
the injected-class-name of a template base class as a type name,
and lookup of the name found the declaration of the template in the
enclosing scope. Now lookup of the name finds the
injected-class-name, which can be used either as a type or as a
template, depending on whether or not the name is followed by a
template argument list. As a result of this change, some code that
was previously accepted may be ill-formed because
1. The injected-class-name is not accessible because it's from a
private base, or
2. The injected-class-name cannot be used as an argument for a
template template parameter.
In either of these cases, the code can be fixed by adding a
nested-name-specifier to explicitly name the template. The first
can be worked around with -fno-access-control; the second is only
rejected with -pedantic.
* A new standard mangling for SIMD vector types has been added, to
avoid name clashes on systems with vectors of varying length. By
default the compiler still uses the old mangling, but emits aliases
with the new mangling on targets that support strong aliases. Users
can switch over entirely to the new mangling with -fabi-version=4
or -fabi-version=0. -Wabi will now warn about code that uses the
old mangling.
* The command-line option -ftemplate-depth-N is now written as
-ftemplate-depth=N and the old form is deprecated.
* Conversions between NULL and non-pointer types are now warned by
default. The new option -Wno-conversion-null disables these
warnings. Previously these warnings were only available when using
-Wconversion explicitly.

Runtime Library (libstdc++)

* Improved experimental support for the upcoming ISO C++ standard,
C++0x, including:
+ Support for <future>, <functional>, and <random>.
+ Existing facilities now exploit explicit operators and the
newly implemented core C++0x features.
+ The header <cstdatomic> has been renamed to <atomic>.
* An experimental [15]profile mode has been added. This is an
implementation of many C++ standard library constructs with an
additional analysis layer that gives performance improvement advice
based on recognition of suboptimal usage patterns. For example,
#include <vector>
int main()
{
std::vector<int> v;
for (int k = 0; k < 1024; ++k)
v.insert(v.begin(), k);
}

When instrumented via the profile mode, can return suggestions
about the initial size and choice of the container used as follows:
vector-to-list: improvement = 5: call stack = 0x804842c ...
: advice = change std::vector to std::list
vector-size: improvement = 3: call stack = 0x804842c ...
: advice = change initial container size from 0 to 1024

These constructs can be substituted for the normal libstdc++
constructs on a piecemeal basis, or all existing components can be
transformed via the -D_GLIBCXX_PROFILE macro.
* [16]Support for decimal floating-point arithmetic (aka ISO C++ TR
24733) has been added. This support is in header file
<decimal/decimal>, uses namespace std::decimal, and includes
classes decimal32, decimal64, and decimal128.
* Sources have been audited for application of function attributes
nothrow, const, pure, and noreturn.
* Python pretty-printers have been added for many standard library
components that simplify the internal representation and present a
more intuitive view of components when used with
appropriately-advanced versions of GDB. For more information,
please consult the more [17]detailed description.
* The default behavior for comparing typeinfo names has changed, so
in <typeinfo>, __GXX_MERGED_TYPEINFO_NAMES now defaults to zero.
* The new -static-libstdc++ option directs g++ to link the C++
library statically, even if the default would normally be to link
it dynamically.

[18]Fortran

* The COMMON default padding has been changed - instead of adding the
padding before a variable it is now added afterwards, which
increases the compatibility with other vendors and helps to obtain
the correct output in some cases. Cf. also the -falign-commons
option ([19]added in 4.4).
* The -finit-real= option now also supports the value snan for
signaling not-a-number; to be effective, one additionally needs to
enable trapping (e.g. via -ffpe-trap=). Note: Compile-time
optimizations can turn a signaling NaN into a quiet one.
* The new option -fcheck= has been added with the options bounds,
array-temps, do, pointer, and recursive. The bounds and array-temps
options are equivalent to -fbounds-check and
-fcheck-array-temporaries. The do option checks for invalid
modification of loop iteration variables, and the recursive option
tests for recursive calls to subroutines/functions which are not
marked as recursive. With pointer pointer association checks in
calls are performed; however, neither undefined pointers nor
pointers in expressions are handled. Using -fcheck=all enables all
these run-time checks.
* The run-time checking -fcheck=bounds now warns about invalid string
lengths of character dummy arguments. Additionally, more
compile-time checks have been added.
* The new option [20]-fno-protect-parens has been added; if set, the
compiler may reorder REAL and COMPLEX expressions without regard to
parentheses.
* GNU Fortran no longer links against libgfortranbegin. As before,
MAIN__ (assembler symbol name) is the actual Fortran main program,
which is invoked by the main function. However, main is now
generated and put in the same object file as MAIN__. For the time
being, libgfortranbegin still exists for backward compatibility.
For details see the new [21]Mixed-Language Programming chapter in
the manual.
* The I/O library was restructured for performance and cleaner code.
* Array assignments and WHERE are now run in parallel when OpenMP's
WORKSHARE is used.
* The experimental option -fwhole-file was added. The option allows
whole-file checking of procedure arguments and allows for better
optimizations. It can also be used with -fwhole-program, which is
now also supported in gfortran.
* More Fortran 2003 and Fortran 2008 mathematical functions can now
be used as initialization expressions.
* Some extended attributes such as STDCALL are now supported via the
[22]GCC$ compiler directive.
* For Fortran 77 compatibility: If -fno-sign-zero is used, the SIGN
intrinsic behaves now as if zero were always positive.
* For legacy compatibiliy: On Cygwin and MinGW, the special files
CONOUT$ and CONIN$ (and CONERR$ which maps to CONOUT$) are now
supported.
* Fortran 2003 support has been extended:
+ Procedure-pointer function results and procedure-pointer
components (including PASS),
+ allocatable scalars (experimental),
+ DEFERRED type-bound procedures,
+ the ERRMSG= argument of the ALLOCATE and DEALLOCATE statements
have been implemented.
+ The ALLOCATE statement supports type-specs and the SOURCE=
argument.
+ OPERATOR(*) and ASSIGNMENT(=) are now allowed as GENERIC
type-bound procedure (i.e. as type-bound operators).
+ Rounding (ROUND=, RZ, ...) for output is now supported.
+ The INT_FAST{8,16,32,64,128}_T kind type parameters of the
intrinsic module ISO_C_BINDING are now supported, except for
the targets listed above as ones where GCC does not have
<stdint.h> type information.
+ Extensible derived types with type-bound procedure or
procedure pointer with PASS attribute now have to use CLASS in
line with the Fortran 2003 standard; the workaround to use
TYPE is no longer supported.
+ [23]Experimental, incomplete support for polymorphism,
including CLASS, SELECT TYPE and dynamic dispatch of
type-bound procedure calls. Some features do not work yet such
as unlimited polymorphism (CLASS(*)).
* Fortran 2008 support has been extended:
+ The OPEN statement now supports the NEWUNIT= option, which
returns a unique file unit, thus preventing inadvertent use of
the same unit in different parts of the program.
+ Support for unlimited format items has been added.
+ The INT{8,16,32} and REAL{32,64,128} kind type parameters of
the intrinsic module ISO_FORTRAN_ENV are now supported.
+ Using complex arguments with TAN, SINH, COSH, TANH, ASIN,
ACOS, and ATAN is now possible; the functions ASINH, ACOSH,
and ATANH have been added (for real and complex arguments) and
ATAN(Y,X) is now an alias for ATAN2(Y,X).
+ The BLOCK construct has been implemented.

[24]New Targets and Target Specific Improvements

AIX

* Full cross-toolchain support now available with GNU Binutils

ARM

* GCC now supports the Cortex-M0 and Cortex-A5 processors.
* GCC now supports the ARM v7E-M architecture.
* GCC now supports VFPv4-based FPUs and FPUs with
single-precision-only VFP.
* GCC has many improvements to optimization for other ARM processors,
including scheduling support for the integer pipeline on Cortex-A9.
* GCC now supports the IEEE 754-2008 half-precision floating-point
type, and a variant ARM-specific half-precision type. This type is
specified using __fp16, with the layout determined by
-mfp16-format. With appropriate -mfpu options, the Cortex-A9 and
VFPv4 half-precision instructions will be used.
* GCC now supports the variant of AAPCS that uses VFP registers for
parameter passing and return values.

AVR

* The -mno-tablejump option has been removed because it has the same
effect as the -fno-jump-tables option.
* Added support for these new AVR devices:
+ ATmega8U2
+ ATmega16U2
+ ATmega32U2

[25]IA-32/x86-64

* GCC now will set the default for -march= based on the configure
target.
* GCC now supports handling floating-point excess precision arising
from use of the x87 floating-point unit in a way that conforms to
ISO C99. This is enabled with -fexcess-precision=standard and with
standards conformance options such as -std=c99, and may be disabled
using -fexcess-precision=fast.
* Support for the Intel Atom processor is now available through the
-march=atom and -mtune=atom options.
* A new -mcrc32 option is now available to enable crc32 intrinsics.
* A new -mmovbe option is now available to enable GCC to use the
movbe instruction to implement __builtin_bswap32 and
__builtin_bswap64.
* SSE math now can be enabled by default at configure time with the
new --with-fpmath=sse option.
* There is a new intrinsic header file, <x86intrin.h>. It should be
included before using any IA-32/x86-64 intrinsics.
* Support for the XOP, FMA4, and LWP instruction sets for the AMD
Orochi processors are now available with the -mxop, -mfma4, and
-mlwp options.
* The -mabm option enables GCC to use the popcnt and lzcnt
instructions on AMD processors.
* The -mpopcnt option enables GCC to use the popcnt instructions on
both AMD and Intel processors.

M68K/ColdFire

* GCC now supports ColdFire 51xx, 5221x, 5225x, 52274, 52277, 5301x
and 5441x devices.
* GCC now supports thread-local storage (TLS) on M68K and ColdFire
processors.

[26]MeP

Support has been added for the Toshiba Media embedded Processor (MeP,
or mep-elf) embedded target.

MIPS

* GCC now supports MIPS 1004K processors.
* GCC can now be configured with options --with-arch-32,
--with-arch-64, --with-tune-32 and --with-tune-64 to control the
default optimization separately for 32-bit and 64-bit modes.
* MIPS targets now support an alternative _mcount interface, in which
register $12 points to the function's save slot for register $31.
This interface is selected by the -mcount-ra-address option; see
the documentation for more details.
* GNU/Linux targets can now generate read-only .eh_frame sections.
This optimization requires GNU binutils 2.20 or above, and is only
available if GCC is configured with a suitable version of binutils.
* GNU/Linux targets can now attach special relocations to indirect
calls, so that the linker can turn them into direct jumps or
branches. This optimization requires GNU binutils 2.20 or later,
and is automatically selected if GCC is configured with an
appropriate version of binutils. It can be explicitly enabled or
disabled using the -mrelax-pic-calls command-line option.
* GCC now generates more heavily-optimized atomic operations on
Octeon processors.
* MIPS targets now support the -fstack-protector option.
* GCC now supports an -msynci option, which specifies that synci is
enough to flush the instruction cache, without help from the
operating system. GCC uses this information to optimize
automatically-generated cache flush operations, such as those used
for nested functions in C. There is also a --with-synci
configure-time option, which makes -msynci the default.
* GCC supports four new function attributes for interrupt handlers:
interrupt, use_shadow_register_set, keep_interrupts_masked and
use_debug_exception_return. See the documentation for more details
about these attributes.

[27]RS/6000 (POWER/PowerPC)

* GCC now supports the Power ISA 2.06, which includes the VSX
instructions that add vector 64-bit floating point support, new
population count instructions, and conversions between floating
point and unsigned types.
* Support for the power7 processor is now available through the
-mcpu=power7 and -mtune=power7.
* GCC will now vectorize loops that contain simple math functions
like copysign when generating code for altivec or VSX targets.
* Support for the A2 processor is now available through the -mcpu=a2
and -mtune=a2 options.
* Support for the 476 processor is now available through the
-mcpu={476,476fp} and -mtune={476,476fp} options.
* Support for the e500mc64 processor is now available through the
-mcpu=e500mc64 and -mtune=e500mc64 options.
* GCC can now be configured with options --with-cpu-32,
--with-cpu-64, --with-tune-32 and --with-tune-64 to control the
default optimization separately for 32-bit and 64-bit modes.
* Starting with GCC 4.5.4, vectors of type vector long long or vector
long are passed and returned in the same method as other vectors
with the VSX instruction set. Previously the GCC compiler did not
adhere to the ABI for 128-bit vectors with 64-bit integer base
types (PR 48857). This is also fixed in the GCC 4.6.1 release.

[28]RX

Support has been added for the Renesas RX Processor (rx-elf) target.

[29]Operating Systems

[30]Windows (Cygwin and MinGW)

* GCC now installs all the major language runtime libraries as DLLs
when configured with the --enable-shared option.
* GCC now makes use of the new support for aligned common variables
in versions of binutils >= 2.20 to fix bugs in the support for SSE
data types.
* Improvements to the libffi support library increase the reliability
of code generated by GCJ on all Windows platforms. Libgcj is
enabled by default for the first time.
* Libtool improvements simplify installation by placing the generated
DLLs in the correct binaries directory.
* Numerous other minor bugfixes and improvements, and substantial
enhancements to the Fortran language support library.

>

Other significant improvements

Plugins

* It is now possible to extend the compiler without having to modify
its source code. A new option -fplugin=file.so tells GCC to load
the shared object file.so and execute it as part of the compiler.
The internal documentation describes the details on how plugins can
interact with the compiler.

Installation changes

* The move to newer autotools changed default installation
directories and switches to control them: The --with-datarootdir,
--with-docdir, --with-pdfdir, and --with-htmldir switches are not
used any more. Instead, you can now use --datarootdir, --docdir,
--htmldir, and --pdfdir. The default installation directories have
changed as follows according to the GNU Coding Standards:

datarootdir read-only architecture-independent data root [PREFIX/share]
localedir locale-specific message catalogs [DATAROOTDIR/locale]
docdir documentation root [DATAROOTDIR/doc/PACKAGE]
htmldir html documentation [DOCDIR]
dvidir dvi documentation [DOCDIR]
pdfdir pdf documentation [DOCDIR]
psdir ps documentation [DOCDIR]
The following variables have new default values:

datadir read-only architecture-independent data [DATAROOTDIR]
infodir info documentation [DATAROOTDIR/info]
mandir man documentation [DATAROOTDIR/man]

[31]GCC 4.5.1

This is the [32]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.5.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

All languages

* GCC's new link-time optimizer ([33]-flto) now also works on a few
non-ELF targets:
+ Cygwin (*-cygwin*)
+ MinGW (*-mingw*)
+ Darwin on x86-64 (x86_64-apple-darwin*)
LTO is not enabled by default for these targets. To enable LTO, you
should configure with the --enable-lto option.

[34]GCC 4.5.2

This is the [35]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.5.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[36]GCC 4.5.3

This is the [37]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.5.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

On the PowerPC compiler, the Altivec builtin functions vec_ld and
vec_st have been modified to generate the Altivec memory instructions
LVX and STVX, even if the -mvsx option is used. In the initial GCC 4.5
release, these builtin functions were changed to generate VSX memory
reference instructions instead of Altivec memory instructions, but
there are differences between the two instructions. If the VSX
instruction set is available, you can now use the new builtin functions
vec_vsx_ld and vec_vsx_st which always generates the VSX memory
instructions.

[38]GCC 4.5.4

This is the [39]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.5.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

For questions related to the use of GCC, please consult these web
pages and the [40]GCC manuals. If that fails, the
[41][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [42][email protected]. All of [43]our lists have public
archives.

Copyright (C) [44]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [45]maintained by the GCC team. Last modified
2025-01-31.

References

1. https://www.multiprecision.org/
2. https://gcc.gnu.org/install/prerequisites.html
3. https://gcc.gnu.org/ml/gcc/2010-01/msg00510.html
4. https://gcc.gnu.org/gcc-4.4/changes.html#obsoleted
5. https://gcc.gnu.org/gcc-4.5/changes.html#x86
6. https://gcc.gnu.org/PR30789
7. https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-flto-801
8. https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-fwhopr-802
9. https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-fwhole-program-800
10. https://gcc.gnu.org/onlinedocs/gcc/Restricted-Pointers.html
11. https://gcc.gnu.org/gcc-4.5/changes.html#cplusplus
12. https://gcc.gnu.org/gcc-4.5/cxx0x_status.html
13. https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#757
14. https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#176
15. https://gcc.gnu.org/onlinedocs/libstdc++/manual/profile_mode.html
16. https://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#status.iso.tr24733
17. https://sourceware.org/gdb/wiki/STLSupport
18. https://gcc.gnu.org/gcc-4.5/changes.html#Fortran
19. https://gcc.gnu.org/gcc-4.4/changes.html
20. https://gcc.gnu.org/onlinedocs/gfortran/Code-Gen-Options.html
21. https://gcc.gnu.org/onlinedocs/gfortran/Mixed-Language-Programming.html
22. https://gcc.gnu.org/onlinedocs/gfortran/GNU-Fortran-Compiler-Directives.html
23. https://gcc.gnu.org/wiki/OOP
24. https://gcc.gnu.org/gcc-4.5/changes.html#targets
25. https://gcc.gnu.org/gcc-4.5/changes.html#x86
26. https://gcc.gnu.org/gcc-4.5/changes.html#mep
27. https://gcc.gnu.org/gcc-4.5/changes.html#rs6000
28. https://gcc.gnu.org/gcc-4.5/changes.html#rx
29. https://gcc.gnu.org/gcc-4.5/changes.html#os
30. https://gcc.gnu.org/gcc-4.5/changes.html#windows
31. https://gcc.gnu.org/gcc-4.5/changes.html#GCC4.5.1
32. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.5.1
33. https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-flto-801
34. https://gcc.gnu.org/gcc-4.5/changes.html#GCC4.5.2
35. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.5.2
36. https://gcc.gnu.org/gcc-4.5/changes.html#GCC4.5.3
37. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.5.3
38. https://gcc.gnu.org/gcc-4.5/changes.html#GCC4.5.4
39. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.5.4
40. https://gcc.gnu.org/onlinedocs/
41. mailto:[email protected]
42. mailto:[email protected]
43. https://gcc.gnu.org/lists.html
44. https://www.fsf.org/
45. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.4/index.html

GCC 4.4 Release Series

This release series is no longer maintained.

March 13, 2012

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 4.4.7.

This release is a bug-fix release, containing fixes for regressions in
GCC 4.4.6 relative to previous releases of GCC.

Release History

GCC 4.4.7
March 13, 2012 ([2]changes)

GCC 4.4.6
April 16, 2011 ([3]changes)

GCC 4.4.5
October 1, 2010 ([4]changes)

GCC 4.4.4
April 29, 2010 ([5]changes)

GCC 4.4.3
January 21, 2010 ([6]changes)

GCC 4.4.2
October 15, 2009 ([7]changes)

GCC 4.4.1
July 22, 2009 ([8]changes)

GCC 4.4.0
April 21, 2009 ([9]changes)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [10]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [11]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [12]GCC
project web site or contact the [13]GCC development mailing list.

To obtain GCC please use [14]our mirror sites or [15]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [16]GCC manuals. If that fails, the
[17][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [18][email protected]. All of [19]our lists have public
archives.

Copyright (C) [20]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [21]maintained by the GCC team. Last modified
2022-10-26.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-4.4/changes.html
3. https://gcc.gnu.org/gcc-4.4/changes.html
4. https://gcc.gnu.org/gcc-4.4/changes.html
5. https://gcc.gnu.org/gcc-4.4/changes.html
6. https://gcc.gnu.org/gcc-4.4/changes.html
7. https://gcc.gnu.org/gcc-4.4/changes.html
8. https://gcc.gnu.org/gcc-4.4/changes.html
9. https://gcc.gnu.org/gcc-4.4/changes.html
10. https://gcc.gnu.org/gcc-4.4/buildstat.html
11. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
12. https://gcc.gnu.org/index.html
13. mailto:[email protected]
14. https://gcc.gnu.org/mirrors.html
15. https://gcc.gnu.org/git.html
16. https://gcc.gnu.org/onlinedocs/
17. mailto:[email protected]
18. mailto:[email protected]
19. https://gcc.gnu.org/lists.html
20. https://www.fsf.org/
21. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.4/changes.html

GCC 4.4 Release Series
Changes, New Features, and Fixes

The latest release in the 4.4 release series is [1]GCC 4.4.7.

Caveats

* __builtin_stdarg_start has been completely removed from GCC.
Support for <varargs.h> had been deprecated since GCC 4.0. Use
__builtin_va_start as a replacement.
* Some of the errors issued by the C++ front end that could be
downgraded to warnings in previous releases by using -fpermissive
are now warnings by default. They can be converted into errors by
using -pedantic-errors.
* Use of the cpp assertion extension will now emit a warning when
-Wdeprecated or -pedantic is used. This extension has been
deprecated for many years, but never warned about.
* Packed bit-fields of type char were not properly bit-packed on many
targets prior to GCC 4.4. On these targets, the fix in GCC 4.4
causes an ABI change. For example there is no longer a 4-bit
padding between field a and b in this structure:
struct foo
{
char a:4;
char b:8;
} __attribute__ ((packed));
There is a new warning to help identify fields that are affected:
foo.c:5: note: Offset of packed bit-field 'b' has changed in GCC 4.4
The warning can be disabled with -Wno-packed-bitfield-compat.
* On ARM EABI targets, the C++ mangling of the va_list type has been
changed to conform to the current revision of the EABI. This does
not affect the libstdc++ library included with GCC.
* The SCOUNT and POS bits of the MIPS DSP control register are now
treated as global. Previous versions of GCC treated these fields as
call-clobbered instead.
* The MIPS port no longer recognizes the h asm constraint. It was
necessary to remove this constraint in order to avoid generating
unpredictable code sequences.
One of the main uses of the h constraint was to extract the high
part of a multiplication on 64-bit targets. For example:
asm ("dmultu\t%1,%2" : "=h" (result) : "r" (x), "r" (y));
You can now achieve the same effect using 128-bit types:
typedef unsigned int uint128_t __attribute__((mode(TI)));
result = ((uint128_t) x * y) >> 64;
The second sequence is better in many ways. For example, if x and y
are constants, the compiler can perform the multiplication at
compile time. If x and y are not constants, the compiler can
schedule the runtime multiplication better than it can schedule an
asm statement.
* Support for a number of older systems and recently unmaintained or
untested target ports of GCC has been declared obsolete in GCC 4.4.
Unless there is activity to revive them, the next release of GCC
will have their sources permanently removed.
The following ports for individual systems on particular
architectures have been obsoleted:
+ Generic a.out on IA32 and m68k (i[34567]86-*-aout*,
m68k-*-aout*)
+ Generic COFF on ARM, H8300, IA32, m68k and SH (arm-*-coff*,
armel-*-coff*, h8300-*-*, i[34567]86-*-coff*, m68k-*-coff*,
sh-*-*). This does not affect other more specific targets
using the COFF object format on those architectures, or the
more specific H8300 and SH targets (h8300-*-rtems*,
h8300-*-elf*, sh-*-elf*, sh-*-symbianelf*, sh-*-linux*,
sh-*-netbsdelf*, sh-*-rtems*, sh-wrs-vxworks).
+ 2BSD on PDP-11 (pdp11-*-bsd)
+ AIX 4.1 and 4.2 on PowerPC (rs6000-ibm-aix4.[12]*,
powerpc-ibm-aix4.[12]*)
+ Tuning support for Itanium1 (Merced) variants. Note that code
tuned for Itanium2 should also run correctly on Itanium1.
* The protoize and unprotoize utilities have been obsoleted and will
be removed in GCC 4.5. These utilities have not been installed by
default since GCC 3.0.
* Support has been removed for all the [2]configurations obsoleted in
GCC 4.3.
* Unknown -Wno-* options are now silently ignored by GCC if no other
diagnostics are issued. If other diagnostics are issued, then GCC
warns about the unknown options.
* More information on porting to GCC 4.4 from previous versions of
GCC can be found in the [3]porting guide for this release.

General Optimizer Improvements

* A new command-line switch -findirect-inlining has been added. When
turned on it allows the inliner to also inline indirect calls that
are discovered to have known targets at compile time thanks to
previous inlining.
* A new command-line switch -ftree-switch-conversion has been added.
This new pass turns simple initializations of scalar variables in
switch statements into initializations from a static array, given
that all the values are known at compile time and the ratio between
the new array size and the original switch branches does not exceed
the parameter --param switch-conversion-max-branch-ratio (default
is eight).
* A new command-line switch -ftree-builtin-call-dce has been added.
This optimization eliminates unnecessary calls to certain builtin
functions when the return value is not used, in cases where the
calls can not be eliminated entirely because the function may set
errno. This optimization is on by default at -O2 and above.
* A new command-line switch -fconserve-stack directs the compiler to
minimize stack usage even if it makes the generated code slower.
This affects inlining decisions.
* When the assembler supports it, the compiler will now emit unwind
information using assembler .cfi directives. This makes it possible
to use such directives in inline assembler code. The new option
-fno-dwarf2-cfi-asm directs the compiler to not use .cfi
directives.
* The [4]Graphite branch has been merged. This merge has brought in a
new framework for loop optimizations based on a polyhedral
intermediate representation. These optimizations apply to all the
languages supported by GCC. The following new code transformations
are available in GCC 4.4:
+ -floop-interchange performs loop interchange transformations
on loops. Interchanging two nested loops switches the inner
and outer loops. For example, given a loop like:
DO J = 1, M
DO I = 1, N
A(J, I) = A(J, I) * C
ENDDO
ENDDO

loop interchange will transform the loop as if the user had
written:
DO I = 1, N
DO J = 1, M
A(J, I) = A(J, I) * C
ENDDO
ENDDO

which can be beneficial when N is larger than the caches,
because in Fortran, the elements of an array are stored in
memory contiguously by column, and the original loop iterates
over rows, potentially creating at each access a cache miss.
+ -floop-strip-mine performs loop strip mining transformations
on loops. Strip mining splits a loop into two nested loops.
The outer loop has strides equal to the strip size and the
inner loop has strides of the original loop within a strip.
For example, given a loop like:
DO I = 1, N
A(I) = A(I) + C
ENDDO

loop strip mining will transform the loop as if the user had
written:
DO II = 1, N, 4
DO I = II, min (II + 3, N)
A(I) = A(I) + C
ENDDO
ENDDO

+ -floop-block performs loop blocking transformations on loops.
Blocking strip mines each loop in the loop nest such that the
memory accesses of the element loops fit inside caches. For
example, given a loop like:
DO I = 1, N
DO J = 1, M
A(J, I) = B(I) + C(J)
ENDDO
ENDDO

loop blocking will transform the loop as if the user had
written:
DO II = 1, N, 64
DO JJ = 1, M, 64
DO I = II, min (II + 63, N)
DO J = JJ, min (JJ + 63, M)
A(J, I) = B(I) + C(J)
ENDDO
ENDDO
ENDDO
ENDDO

which can be beneficial when M is larger than the caches,
because the innermost loop will iterate over a smaller amount
of data that can be kept in the caches.
* A new register allocator has replaced the old one. It is called
integrated register allocator (IRA) because coalescing, register
live range splitting, and hard register preferencing are done
on-the-fly during coloring. It also has better integration with the
reload pass. IRA is a regional register allocator which uses modern
Chaitin-Briggs coloring instead of Chow's priority coloring used in
the old register allocator. More info about IRA internals and
options can be found in the GCC manuals.
* A new instruction scheduler and software pipeliner, based on the
selective scheduling approach, has been added. The new pass
performs instruction unification, register renaming, substitution
through register copies, and speculation during scheduling. The
software pipeliner is able to pipeline non-countable loops. The new
pass is targeted at scheduling-eager in-order platforms. In GCC 4.4
it is available for the Intel Itanium platform working by default
as the second scheduling pass (after register allocation) at the
-O3 optimization level.
* When using -fprofile-generate with a multi-threaded program, the
profile counts may be slightly wrong due to race conditions. The
new -fprofile-correction option directs the compiler to apply
heuristics to smooth out the inconsistencies. By default the
compiler will give an error message when it finds an inconsistent
profile.
* The new -fprofile-dir=PATH option permits setting the directory
where profile data files are stored when using -fprofile-generate
and friends, and the directory used when reading profile data files
using -fprofile-use and friends.

New warning options

* The new -Wframe-larger-than=NUMBER option directs GCC to emit a
warning if any stack frame is larger than NUMBER bytes. This may be
used to help ensure that code fits within a limited amount of stack
space.
* The command-line option -Wlarger-than-N is now written as
-Wlarger-than=N and the old form is deprecated.
* The new -Wno-mudflap option disables warnings about constructs
which can not be instrumented when using -fmudflap.

New Languages and Language specific improvements

* Version 3.0 of the OpenMP specification is now supported for the C,
C++, and Fortran compilers.
* New character data types, per [5]TR 19769: New character types in
C, are now supported for the C compiler in -std=gnu99 mode, as
__CHAR16_TYPE__ and __CHAR32_TYPE__, and for the C++ compiler in
-std=c++0x and -std=gnu++0x modes, as char16_t and char32_t too.

C family

* A new optimize attribute was added to allow programmers to change
the optimization level and particular optimization options for an
individual function. You can also change the optimization options
via the GCC optimize pragma for functions defined after the pragma.
The GCC push_options pragma and the GCC pop_options pragma allow
you temporarily save and restore the options used. The GCC
reset_options pragma restores the options to what was specified on
the command line.
* Uninitialized warnings do not require enabling optimization
anymore, that is, -Wuninitialized can be used together with -O0.
Nonetheless, the warnings given by -Wuninitialized will probably be
more accurate if optimization is enabled.
* -Wparentheses now warns about expressions such as (!x | y) and (!x
& y). Using explicit parentheses, such as in ((!x) | y), silences
this warning.
* -Wsequence-point now warns within if, while,do while and for
conditions, and within for begin/end expressions.
* A new option -dU is available to dump definitions of preprocessor
macros that are tested or expanded.

C++

* [6]Improved experimental support for the upcoming ISO C++ standard,
C++0x. Including support for auto, inline namespaces, generalized
initializer lists, defaulted and deleted functions, new character
types, and scoped enums.
* Those errors that may be downgraded to warnings to build legacy
code now mention -fpermissive when -fdiagnostics-show-option is
enabled.
* -Wconversion now warns if the result of a static_cast to enumeral
type is unspecified because the value is outside the range of the
enumeral type.
* -Wuninitialized now warns if a non-static reference or non-static
const member appears in a class without constructors.
* G++ now properly implements value-initialization, so objects with
an initializer of () and an implicitly defined default constructor
will be zero-initialized before the default constructor is called.

Runtime Library (libstdc++)

* Improved experimental support for the upcoming ISO C++ standard,
C++0x, including:
+ Support for <chrono>, <condition_variable>, <cstdatomic>,
<forward_list>, <initializer_list>, <mutex>, <ratio>,
<system_error>, and <thread>.
+ unique_ptr, <algorithm> additions, exception propagation, and
support for the new character types in <string> and <limits>.
+ Existing facilities now exploit initializer lists, defaulted
and deleted functions, and the newly implemented core C++0x
features.
+ Some standard containers are more efficient together with
stateful allocators, i.e., no allocator is constructed on the
fly at element construction time.
* Experimental support for non-standard pointer types in containers.
* The long standing libstdc++/30928 has been fixed for targets
running glibc 2.10 or later.
* As usual, many small and larger bug fixes, in particular quite a
few corner cases in <locale>.

Fortran

* GNU Fortran now employs libcpp directly instead of using cc1 as an
external preprocessor. The [7]-cpp option was added to allow manual
invocation of the preprocessor without relying on filename
extensions.
* The [8]-Warray-temporaries option warns about array temporaries
generated by the compiler, as an aid to optimization.
* The [9]-fcheck-array-temporaries option has been added, printing a
notification at run time, when an array temporary had to be created
for an function argument. Contrary to -Warray-temporaries the
warning is only printed if the array is noncontiguous.
* Improved generation of DWARF debugging symbols
* If using an intrinsic not part of the selected standard (via -std=
and -fall-intrinsics) gfortran will now treat it as if this
procedure were declared EXTERNAL and try to link to a user-supplied
procedure. -Wintrinsics-std will warn whenever this happens. The
now-useless option -Wnonstd-intrinsic was removed.
* The flag -falign-commons has been added to control the alignment of
variables in COMMON blocks, which is enabled by default in line
with previous GCC version. Using -fno-align-commons one can force
commons to be contiguous in memory as required by the Fortran
standard, however, this slows down the memory access. The option
-Walign-commons, which is enabled by default, warns when padding
bytes were added for alignment. The proper solution is to sort the
common objects by decreasing storage size, which avoids the
alignment problems.
* Fortran 2003 support has been extended:
+ Wide characters (ISO 10646, UCS-4, kind=4) and UTF-8 I/O is
now supported (except internal reads from/writes to wide
strings). [10]-fbackslash now supports also \unnnn and
\Unnnnnnnn to enter Unicode characters.
+ Asynchronous I/O (implemented as synchronous I/O) and the
decimal=, size=, sign=, pad=, blank=, and delim= specifiers
are now supported in I/O statements.
+ Support for Fortran 2003 structure constructors and for array
constructor with typespec has been added.
+ Procedure Pointers (but not yet as component in derived types
and as function results) are now supported.
+ Abstract types, type extension, and type-bound procedures
(both PROCEDURE and GENERIC but not as operators). Note: As
CLASS/polymorphyic types are not implemented, type-bound
procedures with PASS accept as non-standard extension TYPE
arguments.
* Fortran 2008 support has been added:
+ The -std=f2008 option and support for the file extensions
.f2008 and .F2008 has been added.
+ The g0 format descriptor is now supported.
+ The Fortran 2008 mathematical intrinsics ASINH, ACOSH, ATANH,
ERF, ERFC, GAMMA, LOG_GAMMA, BESSEL_*, HYPOT, and ERFC_SCALED
are now available (some of them existed as GNU extension
before). Note: The hyperbolic functions are not yet supporting
complex arguments and the three- argument version of BESSEL_*N
is not available.
+ The bit intrinsics LEADZ and TRAILZ have been added.

Java (GCJ)

Ada

* The Ada runtime now supports multilibs on many platforms including
x86_64, SPARC and PowerPC. Their build is enabled by default.

[11]New Targets and Target Specific Improvements

ARM

* GCC now supports optimizing for the Cortex-A9, Cortex-R4 and
Cortex-R4F processors and has many other improvements to
optimization for ARM processors.
* GCC now supports the VFPv3 variant with 16 double-precision
registers with -mfpu=vfpv3-d16. The option -mfpu=vfp3 has been
renamed to -mfpu=vfpv3.
* GCC now supports the -mfix-cortex-m3-ldrd option to work around an
erratum on Cortex-M3 processors.
* GCC now supports the __sync_* atomic operations for ARM EABI
GNU/Linux.
* The section anchors optimization is now enabled by default when
optimizing for ARM.
* GCC now uses a new EABI-compatible profiling interface for EABI
targets. This requires a function __gnu_mcount_nc, which is
provided by GNU libc versions 2.8 and later.

AVR

* The -mno-tablejump option has been deprecated because it has the
same effect as the -fno-jump-tables option.
* Added support for these new AVR devices:
+ ATA6289
+ ATtiny13A
+ ATtiny87
+ ATtiny167
+ ATtiny327
+ ATmega8C1
+ ATmega16C1
+ ATmega32C1
+ ATmega8M1
+ ATmega16M1
+ ATmega32M1
+ ATmega32U4
+ ATmega16HVB
+ ATmega4HVD
+ ATmega8HVD
+ ATmega64C1
+ ATmega64M1
+ ATmega16U4
+ ATmega32U6
+ ATmega128RFA1
+ AT90PWM81
+ AT90SCR100
+ M3000F
+ M3000S
+ M3001B

IA-32/x86-64

* Support for Intel AES built-in functions and code generation is
available via -maes.
* Support for Intel PCLMUL built-in function and code generation is
available via -mpclmul.
* Support for Intel AVX built-in functions and code generation is
available via -mavx.
* Automatically align the stack for local variables with alignment
requirement.
* GCC can now utilize the SVML library for vectorizing calls to a set
of C99 functions if -mveclibabi=svml is specified and you link to
an SVML ABI compatible library.
* On x86-64, the ABI has been changed in the following cases to
conform to the x86-64 ABI:
+ Passing/returning structures with flexible array member:
struct foo
{
int i;
int flex[];
};
+ Passing/returning structures with complex float member:
struct foo
{
int i;
__complex__ float f;
};
+ Passing/returning unions with long double member:
union foo
{
int x;
long double ld;
};
Code built with previous versions of GCC that uses any of these is
not compatible with code built with GCC 4.4.0 or later.
* A new target attribute was added to allow programmers to change the
target options like -msse2 or -march=k8 for an individual function.
You can also change the target options via the GCC target pragma
for functions defined after the pragma.
* GCC can now be configured with options --with-arch-32,
--with-arch-64, --with-cpu-32, --with-cpu-64, --with-tune-32 and
--with-tune-64 to control the default optimization separately for
32-bit and 64-bit modes.

IA-32/IA64

* Support for __float128 (TFmode) IEEE quad type and corresponding
TCmode IEEE complex quad type is available via the soft-fp library
on IA-32/IA64 targets. This includes basic arithmetic operations
(addition, subtraction, negation, multiplication and division) on
__float128 real and TCmode complex values, the full set of IEEE
comparisons between __float128 values, conversions to and from
float, double and long double floating point types, as well as
conversions to and from signed or unsigned integer, signed or
unsigned long integer and signed or unsigned quad (TImode, IA64
only) integer types. Additionally, all operations generate the full
set of IEEE exceptions and support the full set of IEEE rounding
modes.

M68K/ColdFire

* GCC now supports instruction scheduling for ColdFire V1, V3 and V4
processors. (Scheduling support for ColdFire V2 processors was
added in GCC 4.3.)
* GCC now supports the -mxgot option to support programs requiring
many GOT entries on ColdFire.
* The m68k-*-linux-gnu target now builds multilibs by default.

MIPS

* MIPS Technologies have extended the original MIPS SVR4 ABI to
include support for procedure linkage tables (PLTs) and copy
relocations. These extensions allow GNU/Linux executables to use a
significantly more efficient code model than the one defined by the
original ABI.
GCC support for this code model is available via a new command-line
option, -mplt. There is also a new configure-time option,
--with-mips-plt, to make -mplt the default.
The new code model requires support from the assembler, the linker,
and the runtime C library. This support is available in binutils
2.19 and GLIBC 2.9.
* GCC can now generate MIPS16 code for 32-bit GNU/Linux executables
and 32-bit GNU/Linux shared libraries. This feature requires GNU
binutils 2.19 or above.
* Support for RMI's XLR processor is now available through the
-march=xlr and -mtune=xlr options.
* 64-bit targets can now perform 128-bit multiplications inline,
instead of relying on a libgcc function.
* Native GNU/Linux toolchains now support -march=native and
-mtune=native, which select the host processor.
* GCC now supports the R10K, R12K, R14K and R16K processors. The
canonical -march= and -mtune= names for these processors are
r10000, r12000, r14000 and r16000 respectively.
* GCC can now work around the side effects of speculative execution
on R10K processors. Please see the documentation of the
-mr10k-cache-barrier option for details.
* Support for the MIPS64 Release 2 instruction set has been added.
The option -march=mips64r2 enables generation of these
instructions.
* GCC now supports Cavium Networks' Octeon processor. This support is
available through the -march=octeon and -mtune=octeon options.
* GCC now supports STMicroelectronics' Loongson 2E/2F processors. The
canonical -march= and -mtune= names for these processors are
loongson2e and loongson2f.

[12]picochip

Picochip is a 16-bit processor. A typical picoChip contains over 250
small cores, each with small amounts of memory. There are three
processor variants (STAN, MEM and CTRL) with different instruction sets
and memory configurations and they can be chosen using the -mae option.

This port is intended to be a "C" only port.

Power Architecture and PowerPC

* GCC now supports the e300c2, e300c3 and e500mc processors.
* GCC now supports Xilinx processors with a single-precision FPU.
* Decimal floating point is now supported for e500 processors.

S/390, zSeries and System z9/z10

* Support for the IBM System z10 EC/BC processor has been added. When
using the -march=z10 option, the compiler will generate code making
use of instructions provided by the General-Instruction-Extension
Facility and the Execute-Extension Facility.

VxWorks

* GCC now supports the thread-local storage mechanism used on
VxWorks.

Xtensa

* GCC now supports thread-local storage (TLS) for Xtensa processor
configurations that include the Thread Pointer option. TLS also
requires support from the assembler and linker; this support is
provided in the GNU binutils beginning with version 2.19.

Documentation improvements

Other significant improvements

[13]GCC 4.4.1

This is the [14]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.4.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[15]GCC 4.4.2

This is the [16]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.4.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[17]GCC 4.4.3

This is the [18]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.4.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[19]GCC 4.4.4

This is the [20]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.4.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[21]GCC 4.4.5

This is the [22]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.4.5 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[23]GCC 4.4.6

This is the [24]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.4.6 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[25]GCC 4.4.7

This is the [26]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.4.7 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

For questions related to the use of GCC, please consult these web
pages and the [27]GCC manuals. If that fails, the
[28][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [29][email protected]. All of [30]our lists have public
archives.

Copyright (C) [31]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [32]maintained by the GCC team. Last modified
2025-01-31.

References

1. https://gcc.gnu.org/gcc-4.4/changes.html#4.4.7
2. https://gcc.gnu.org/gcc-4.3/changes.html#obsoleted
3. https://gcc.gnu.org/gcc-4.4/porting_to.html
4. https://gcc.gnu.org/wiki/Graphite
5. https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1040.pdf
6. https://gcc.gnu.org/gcc-4.4/cxx0x_status.html
7. https://gcc.gnu.org/onlinedocs/gfortran/Preprocessing-Options.html
8. https://gcc.gnu.org/onlinedocs/gfortran/Error-and-Warning-Options.html#index-g_t_0040code_007bWarray-temporaries_007d-125
9. https://gcc.gnu.org/onlinedocs/gfortran/Code-Gen-Options.html#index-g_t_0040code_007bfcheck-array-temporaries_007d-221
10. https://gcc.gnu.org/onlinedocs/gfortran/Fortran-Dialect-Options.html#index-g_t_0040code_007bbackslash_007d-34
11. https://gcc.gnu.org/gcc-4.4/changes.html#targets
12. https://gcc.gnu.org/gcc-4.4/changes.html#picochip
13. https://gcc.gnu.org/gcc-4.4/changes.html#GCC4.4.1
14. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.4.1
15. https://gcc.gnu.org/gcc-4.4/changes.html#GCC4.4.2
16. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.4.2
17. https://gcc.gnu.org/gcc-4.4/changes.html#GCC4.4.3
18. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.4.3
19. https://gcc.gnu.org/gcc-4.4/changes.html#GCC4.4.4
20. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.4.4
21. https://gcc.gnu.org/gcc-4.4/changes.html#GCC4.4.5
22. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.4.5
23. https://gcc.gnu.org/gcc-4.4/changes.html#GCC4.4.6
24. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.4.6
25. https://gcc.gnu.org/gcc-4.4/changes.html#GCC4.4.7
26. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.4.7
27. https://gcc.gnu.org/onlinedocs/
28. mailto:[email protected]
29. mailto:[email protected]
30. https://gcc.gnu.org/lists.html
31. https://www.fsf.org/
32. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.3/index.html

GCC 4.3 Release Series

(This release series is no longer supported.)

Jun 27, 2011

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 4.3.6.

This release is a bug-fix release, containing fixes for regressions in
GCC 4.3.5 relative to previous releases of GCC.

Release History

GCC 4.3.6
Jun 27, 2011 ([2]changes)

GCC 4.3.5
May 22, 2010 ([3]changes)

GCC 4.3.4
August 4, 2009 ([4]changes)

GCC 4.3.3
January 24, 2009 ([5]changes)

GCC 4.3.2
August 27, 2008 ([6]changes)

GCC 4.3.1
June 6, 2008 ([7]changes)

GCC 4.3.0
March 5, 2008 ([8]changes)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [9]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [10]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [11]GCC
project web site or contact the [12]GCC development mailing list.

To obtain GCC please use [13]our mirror sites or [14]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [15]GCC manuals. If that fails, the
[16][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [17][email protected]. All of [18]our lists have public
archives.

Copyright (C) [19]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [20]maintained by the GCC team. Last modified
2022-10-26.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-4.3/changes.html
3. https://gcc.gnu.org/gcc-4.3/changes.html
4. https://gcc.gnu.org/gcc-4.3/changes.html
5. https://gcc.gnu.org/gcc-4.3/changes.html
6. https://gcc.gnu.org/gcc-4.3/changes.html
7. https://gcc.gnu.org/gcc-4.3/changes.html
8. https://gcc.gnu.org/gcc-4.3/changes.html
9. https://gcc.gnu.org/gcc-4.3/buildstat.html
10. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
11. https://gcc.gnu.org/index.html
12. mailto:[email protected]
13. https://gcc.gnu.org/mirrors.html
14. https://gcc.gnu.org/git.html
15. https://gcc.gnu.org/onlinedocs/
16. mailto:[email protected]
17. mailto:[email protected]
18. https://gcc.gnu.org/lists.html
19. https://www.fsf.org/
20. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.3/changes.html

GCC 4.3 Release Series
Changes, New Features, and Fixes

The latest release in the 4.3 release series is [1]GCC 4.3.5.

Caveats

* GCC requires the [2]GMP and [3]MPFR libraries for building all the
various front-end languages it supports. See the [4]prerequisites
page for version requirements.
* ColdFire targets now treat long double as having the same format as
double. In earlier versions of GCC, they used the 68881 long double
format instead.
* The m68k-uclinux target now uses the same calling conventions as
m68k-linux-gnu. You can select the original calling conventions by
configuring for m68k-uclinuxoldabi instead. Note that
m68k-uclinuxoldabi also retains the original 80-bit long double on
ColdFire targets.
* The -fforce-mem option has been removed because it has had no
effect in the last few GCC releases.
* The i386 -msvr3-shlib option has been removed since it is no longer
used.
* Fastcall for i386 has been changed not to pass aggregate arguments
in registers, following Microsoft compilers.
* Support for the AOF assembler has been removed from the ARM back
end; this affects only the targets arm-semi-aof and armel-semi-aof,
which are no longer recognized. We removed these targets without a
deprecation period because we discovered that they have been
unusable since GCC 4.0.0.
* Support for the TMS320C3x/C4x processor (targets c4x-* and tic4x-*)
has been removed. This support had been deprecated since GCC 4.0.0.
* Support for a number of older systems and recently unmaintained or
untested target ports of GCC has been declared obsolete in GCC 4.3.
Unless there is activity to revive them, the next release of GCC
will have their sources permanently removed.
All GCC ports for the following processor architectures have been
declared obsolete:
+ Morpho MT (mt-*)
The following aliases for processor architectures have been
declared obsolete. Users should use the indicated generic target
names instead, with compile-time options such as -mcpu or
configure-time options such as --with-cpu to control the
configuration more precisely.
+ strongarm*-*-*, ep9312*-*-*, xscale*-*-* (use arm*-*-*
instead).
+ parisc*-*-* (use hppa*-*-* instead).
+ m680[012]0-*-* (use m68k-*-* instead).
All GCC ports for the following operating systems have been
declared obsolete:
+ BeOS (*-*-beos*)
+ kaOS (*-*-kaos*)
+ GNU/Linux using the a.out object format (*-*-linux*aout*)
+ GNU/Linux using version 1 of the GNU C Library
(*-*-linux*libc1*)
+ Solaris versions before Solaris 7 (*-*-solaris2.[0-6],
*-*-solaris2.[0-6].*)
+ Miscellaneous System V (*-*-sysv*)
+ WindISS (*-*-windiss*)
Also, those for some individual systems on particular architectures
have been obsoleted:
+ UNICOS/mk on DEC Alpha (alpha*-*-unicosmk*)
+ CRIS with a.out object format (cris-*-aout)
+ BSD 4.3 on PA-RISC (hppa1.1-*-bsd*)
+ OSF/1 on PA-RISC (hppa1.1-*-osf*)
+ PRO on PA-RISC (hppa1.1-*-pro*)
+ Sequent PTX on IA32 (i[34567]86-sequent-ptx4*,
i[34567]86-sequent-sysv4*)
+ SCO Open Server 5 on IA32 (i[34567]86-*-sco3.2v5*)
+ UWIN on IA32 (i[34567]86-*-uwin*) (support for UWIN as a host
was previously [5]removed in 2001, leaving only the support
for UWIN as a target now being deprecated)
+ ChorusOS on PowerPC (powerpc-*-chorusos*)
+ All VAX configurations apart from NetBSD and OpenBSD
(vax-*-bsd*, vax-*-sysv*, vax-*-ultrix*)
* The [6]-Wconversion option has been modified. Its purpose now is to
warn for implicit conversions that may alter a value. This new
behavior is available for both C and C++. Warnings about
conversions between signed and unsigned integers can be disabled by
using -Wno-sign-conversion. In C++, they are disabled by default
unless -Wsign-conversion is explicitly requested. The old behavior
of -Wconversion, that is, warn for prototypes causing a type
conversion that is different from what would happen to the same
argument in the absence of a prototype, has been moved to a new
option -Wtraditional-conversion, which is only available for C.
* The -m386, -m486, -mpentium and -mpentiumpro tuning options have
been removed because they were deprecated for more than 3 GCC major
releases. Use -mtune=i386, -mtune=i486, -mtune=pentium or
-mtune=pentiumpro as a replacement.
* The -funsafe-math-optimizations option now automatically turns on
-fno-trapping-math in addition to -fno-signed-zeros, as it enables
reassociation and thus may introduce or remove traps.
* The -ftree-vectorize option is now on by default under -O3. In
order to generate code for a SIMD extension, it has to be enabled
as well: use -maltivec for PowerPC platforms and -msse/-msse2 for
i?86 and x86_64.
* More information on porting to GCC 4.3 from previous versions of
GCC can be found in the [7]porting guide for this release.

General Optimizer Improvements

* The GCC middle-end has been integrated with the MPFR library. This
allows GCC to evaluate and replace at compile-time calls to
built-in math functions having constant arguments with their
mathematically equivalent results. In making use of MPFR, GCC can
generate correct results regardless of the math library
implementation or floating point precision of the host platform.
This also allows GCC to generate identical results regardless of
whether one compiles in native or cross-compile configurations to a
particular target. The following built-in functions take advantage
of this new capability: acos, acosh, asin, asinh, atan2, atan,
atanh, cbrt, cos, cosh, drem, erf, erfc, exp10, exp2, exp, expm1,
fdim, fma, fmax, fmin, gamma_r, hypot, j0, j1, jn, lgamma_r, log10,
log1p, log2, log, pow10, pow, remainder, remquo, sin, sincos, sinh,
tan, tanh, tgamma, y0, y1 and yn. The float and long double
variants of these functions (e.g. sinf and sinl) are also handled.
The sqrt and cabs functions with constant arguments were already
optimized in prior GCC releases. Now they also use MPFR.
* A new forward propagation pass on RTL was added. The new pass
replaces several slower transformations, resulting in compile-time
improvements as well as better code generation in some cases.
* A new command-line switch -frecord-gcc-switches has been added to
GCC, although it is only enabled for some targets. The switch
causes the command line that was used to invoke the compiler to be
recorded into the object file that is being created. The exact
format of this recording is target and binary file format
dependent, but it usually takes the form of a note section
containing ASCII text. The switch is related to the -fverbose-asm
switch, but that one only records the information in the assembler
output file as comments, so the information never reaches the
object file.
* The inliner heuristic is now aware of stack frame consumption. New
command-line parameters --param large-stack-frame and --param
large-stack-frame-growth can be used to limit stack frame size
growth caused by inlining.
* During feedback directed optimizations, the expected block size the
memcpy, memset and bzero functions operate on is discovered and for
cases of commonly used small sizes, specialized inline code is
generated.
* __builtin_expect no longer requires its argument to be a compile
time constant.
* Interprocedural optimization was reorganized to work on functions
in SSA form. This enables more precise and cheaper dataflow
analysis and makes writing interprocedural optimizations easier.
The following improvements have been implemented on top of this
framework:
+ Pre-inline optimization: Selected local optimization passes
are run before the inliner (and other interprocedural passes)
are executed. This significantly improves the accuracy of code
growth estimates used by the inliner and reduces the overall
memory footprint for large compilation units.
+ Early inlining (a simple bottom-up inliner pass inlining only
functions whose body is smaller than the expected call
overhead) is now executed with the early optimization passes,
thus inlining already optimized function bodies into an
unoptimized function that is subsequently optimized by early
optimizers. This enables the compiler to quickly eliminate
abstraction penalty in C++ programs.
+ Interprocedural constant propagation now operate on SSA form
increasing accuracy of the analysis.
* A new internal representation for GIMPLE statements has been
contributed, resulting in compile-time memory savings.
* The vectorizer was enhanced to support vectorization of outer
loops, intra-iteration parallelism (loop-aware SLP), vectorization
of strided accesses and loops with multiple data-types. Run-time
dependency testing using loop versioning was added. The cost model,
turned on by -fvect-cost-model, was developed.

New Languages and Language specific improvements

* We have added new command-line options
-finstrument-functions-exclude-function-list and
-finstrument-functions-exclude-file-list. They provide more control
over which functions are annotated by the -finstrument-functions
option.

C family

* Implicit conversions between generic vector types are now only
permitted when the two vectors in question have the same number of
elements and compatible element types. (Note that the restriction
involves compatible element types, not implicitly-convertible
element types: thus, a vector type with element type int may not be
implicitly converted to a vector type with element type unsigned
int.) This restriction, which is in line with specifications for
SIMD architectures such as AltiVec, may be relaxed using the flag
-flax-vector-conversions. This flag is intended only as a
compatibility measure and should not be used for new code.
* -Warray-bounds has been added and is now enabled by default for
-Wall . It produces warnings for array subscripts that can be
determined at compile time to be always out of bounds.
-Wno-array-bounds will disable the warning.
* The constructor and destructor function attributes now accept
optional priority arguments which control the order in which the
constructor and destructor functions are run.
* New [8]command-line options -Wtype-limits, -Wold-style-declaration,
-Wmissing-parameter-type, -Wempty-body, -Wclobbered and
-Wignored-qualifiers have been added for finer control of the
diverse warnings enabled by -Wextra.
* A new function attribute alloc_size has been added to mark up
malloc style functions. For constant sized allocations this can be
used to find out the size of the returned pointer using the
__builtin_object_size() function for buffer overflow checking and
similar. This supplements the already built-in malloc and calloc
constant size handling.
* Integer constants written in binary are now supported as a GCC
extension. They consist of a prefix 0b or 0B, followed by a
sequence of 0 and 1 digits.
* A new predefined macro __COUNTER__ has been added. It expands to
sequential integral values starting from 0. In conjunction with the
## operator, this provides a convenient means to generate unique
identifiers.
* A new command-line option -fdirectives-only has been added. It
enables a special preprocessing mode which improves the performance
of applications like distcc and ccache.
* Fixed-point data types and operators have been added. They are
based on Chapter 4 of the Embedded-C specification (n1169.pdf).
Currently, only MIPS targets are supported.
* Decimal floating-point arithmetic based on draft ISO/IEC TR 24732,
N1241, is now supported as a GCC extension to C for targets
i[34567]86-*-linux-gnu, powerpc*-*-linux-gnu, s390*-ibm-linux-gnu,
and x86_64-*-linux-gnu. The feature introduces new data types
_Decimal32, _Decimal64, and _Decimal128 with constant suffixes DF,
DD, and DL.

C++

* [9]Experimental support for the upcoming ISO C++ standard, C++0x.
* -Wc++0x-compat has been added and is now enabled by default for
-Wall. It produces warnings for constructs whose meaning differs
between ISO C++ 1998 and C++0x.
* The -Wparentheses option now works for C++ as it does for C. It
warns if parentheses are omitted when operators with confusing
precedence are nested. It also warns about ambiguous else
statements. Since -Wparentheses is enabled by -Wall, this may cause
additional warnings with existing C++ code which uses -Wall. These
new warnings may be disabled by using -Wall -Wno-parentheses.
* The -Wmissing-declarations now works for C++ as it does for C.
* The -fvisibility-ms-compat flag was added, to make it easier to
port larger projects using shared libraries from Microsoft's Visual
Studio to ELF and Mach-O systems.
* C++ attribute handling has been overhauled for template arguments
(ie dependent types). In particular, __attribute__((aligned(T)));
works for C++ types.

Runtime Library (libstdc++)

* [10]Experimental support for the upcoming ISO C++ standard, C++0x.
* Support for TR1 mathematical special functions and regular
expressions.
* Default what implementations give more elaborate exception strings
for bad_cast, bad_typeid, bad_exception, and bad_alloc.
* Header dependencies have been streamlined, reducing unnecessary
includes and pre-processed bloat.
* Variadic template implementations of items in <tuple> and
<functional>.
* An experimental [11]parallel mode has been added. This is a
parallel implementation of many C++ Standard library algorithms,
like std::accumulate, std::for_each, std::transform, or std::sort,
to give but four examples. These algorithms can be substituted for
the normal (sequential) libstdc++ algorithms on a piecemeal basis,
or all existing algorithms can be transformed via the
-D_GLIBCXX_PARALLEL macro.
* Debug mode versions of classes in <unordered_set> and
<unordered_map>.
* Formal deprecation of <ext/hash_set> and <ext/hash_map>, which are
now <backward/hash_set> and <backward/hash_map>. This code:
#include <ext/hash_set>
__gnu_cxx::hash_set<int> s;

Can be transformed (in order of preference) to:
#include <tr1/unordered_set>
std::tr1::unordered_set<int> s;

or
#include <backward/hash_set>
__gnu_cxx::hash_set<int> s;

Similar transformations apply to __gnu_cxx::hash_map,
__gnu_cxx::hash_multimap, __gnu_cxx::hash_set,
__gnu_cxx::hash_multiset.

Fortran

* Due to the fact that the GMP and MPFR libraries are required for
all languages, Fortran is no longer special in this regard and is
available by default.
* The [12]-fexternal-blas option has been added, which generates
calls to BLAS routines for intrinsic matrix operations such as
matmul rather than using the built-in algorithms.
* Support to give a backtrace (compiler flag -fbacktrace or
environment variable GFORTRAN_ERROR_BACKTRACE; on glibc systems
only) or a core dump (-fdump-core, GFORTRAN_ERROR_DUMPCORE) when a
run-time error occured.
* GNU Fortran now defines __GFORTRAN__ when it runs the C
preprocessor (CPP).
* The [13]-finit-local-zero, -finit-real, -finit-integer,
-finit-character, and -finit-logical options have been added, which
can be used to initialize local variables.
* The intrinsic procedures [14]GAMMA and [15]LGAMMA have been added,
which calculate the Gamma function and its logarithm. Use EXTERNAL
gamma if you want to use your own gamma function.
* GNU Fortran now regards the backslash character as literal (as
required by the Fortran 2003 standard); using [16]-fbackslash GNU
Fortran interprets backslashes as C-style escape characters.
* The [17]interpretation of binary, octal and hexadecimal (BOZ)
literal constants has been changed. Before they were always
interpreted as integer; now they are bit-wise transferred as
argument of INT, REAL, DBLE and CMPLX as required by the Fortran
2003 standard, and for real and complex variables in DATA
statements or when directly assigned to real and complex variables.
Everywhere else and especially in expressions they are still
regarded as integer constants.
* Fortran 2003 support has been extended:
+ Intrinsic statements IMPORT, PROTECTED, VALUE and VOLATILE
+ Pointer intent
+ Intrinsic module ISO_ENV_FORTRAN
+ Interoperability with C (ISO C Bindings)
+ ABSTRACT INTERFACES and PROCEDURE statements (without POINTER
attribute)
+ Fortran 2003 BOZ

Java (GCJ)

* GCJ now uses the Eclipse Java compiler for its Java parsing needs.
This enables the use of all 1.5 language features, and fixes most
existing front end bugs.
* libgcj now supports all 1.5 language features which require runtime
support: foreach, enum, annotations, generics, and auto-boxing.
* We've made many changes to the tools shipped with gcj.
+ The old jv-scan tool has been removed. This tool never really
worked properly. There is no replacement.
+ gcjh has been rewritten. Some of its more obscure options no
longer work, but are still recognized in an attempt at
compatibility. gjavah is a new program with similar
functionality but different command-line options.
+ grmic and grmiregistry have been rewritten. grmid has been
added.
+ gjar replaces the old fastjar.
+ gjarsigner (used for signing jars), gkeytool (used for key
management), gorbd (for CORBA), gserialver (computes
serialization UIDs), and gtnameserv (also for CORBA) are now
installed.
* The ability to dump the contents of the java run time heap to a
file for off-line analysis has been added. The heap dumps may be
analyzed with the new gc-analyze tool. They may be generated on
out-of-memory conditions or on demand and are controlled by the new
run time class gnu.gcj.util.GCInfo.
* java.util.TimeZone can now read files from /usr/share/zoneinfo to
provide correct, updated, timezone information. This means that
packagers no longer have to update libgcj when a time zone change
is published.

[18]New Targets and Target Specific Improvements

IA-32/x86-64

* Tuning for Intel Core 2 processors is available via -mtune=core2
and -march=core2.
* Tuning for AMD Geode processors is available via -mtune=geode and
-march=geode.
* Code generation of block move (memcpy) and block set (memset) was
rewritten. GCC can now pick the best algorithm (loop, unrolled
loop, instruction with rep prefix or a library call) based on the
size of the block being copied and the CPU being optimized for. A
new option -minline-stringops-dynamically has been added. With this
option string operations of unknown size are expanded such that
small blocks are copied by in-line code, while for large blocks a
library call is used. This results in faster code than
-minline-all-stringops when the library implementation is capable
of using cache hierarchy hints. The heuristic choosing the
particular algorithm can be overwritten via -mstringop-strategy.
Newly also memset of values different from 0 is inlined.
* GCC no longer places the cld instruction before string operations.
Both i386 and x86-64 ABI documents mandate the direction flag to be
clear at the entry of a function. It is now invalid to set the flag
in asm statement without reseting it afterward.
* Support for SSSE3 built-in functions and code generation are
available via -mssse3.
* Support for SSE4.1 built-in functions and code generation are
available via -msse4.1.
* Support for SSE4.2 built-in functions and code generation are
available via -msse4.2.
* Both SSE4.1 and SSE4.2 support can be enabled via -msse4.
* A new set of options -mpc32, -mpc64 and -mpc80 have been added to
allow explicit control of x87 floating point precision.
* Support for __float128 (TFmode) IEEE quad type and corresponding
TCmode IEEE complex quad type is available via the soft-fp library
on x86_64 targets. This includes basic arithmetic operations
(addition, subtraction, negation, multiplication and division) on
__float128 real and TCmode complex values, the full set of IEEE
comparisons between __float128 values, conversions to and from
float, double and long double floating point types, as well as
conversions to and from signed or unsigned integer, signed or
unsigned long integer and signed or unsigned quad (TImode) integer
types. Additionally, all operations generate the full set of IEEE
exceptions and support the full set of IEEE rounding modes.
* GCC can now utilize the ACML library for vectorizing calls to a set
of C99 functions on x86_64 if -mveclibabi=acml is specified and you
link to an ACML ABI compatible library.

ARM

* Compiler and Library support for Thumb-2 and the ARMv7 architecture
has been added.

[19]CRIS

New features

* Compiler and Library support for the CRIS v32 architecture, as
found in Axis Communications ETRAX FS and ARTPEC-3 chips, has been
added.

Configuration changes

* The cris-*-elf target now includes support for CRIS v32, including
libraries, through the -march=v32 option.
* A new crisv32-*-elf target defaults to generate code for CRIS v32.
* A new crisv32-*-linux* target defaults to generate code for CRIS
v32.
* The cris-*-aout target has been obsoleted.

Improved support for built-in functions

* GCC can now use the lz and swapwbr instructions to implement the
__builtin_clz, __builtin_ctz and __builtin_ffs family of functions.
* __builtin_bswap32 is now implemented using the swapwb instruction,
when available.

[20]m68k and ColdFire

New features

* Support for several new ColdFire processors has been added. You can
generate code for them using the new -mcpu option.
* All targets now support ColdFire processors.
* m68k-uclinux targets have improved support for C++ constructors and
destructors, and for shared libraries.
* It is now possible to set breakpoints on the first or last line of
a function, even if there are no statements on that line.

Optimizations

* Support for sibling calls has been added.
* More use is now made of the ColdFire mov3q instruction.
* __builtin_clz is now implemented using the ff1 ColdFire
instruction, when available.
* GCC now honors the -m68010 option. 68010 code now uses clr rather
than move to zero volatile memory.
* 68020 targets and above can now use symbol(index.size*scale)
addresses for indexed array accesses. Earlier compilers would
always load the symbol into a base register first.

Configuration changes

* All m68k and ColdFire targets now allow the default processor to be
set at configure time using --with-cpu.
* A --with-arch configuration option has been added. This option
allows you to restrict a target to ColdFire or non-ColdFire
processors.

Preprocessor macros

* An __mcfv*__ macro is now defined for all ColdFire targets.
(Earlier versions of GCC only defined __mcfv4e__.)
* __mcf_cpu_*, __mcf_family_* and __mcffpu__ macros have been added.
* All targets now define __mc68010 and __mc68010__ when generating
68010 code.

Command-line changes

* New command-line options -march, -mcpu, -mtune and -mhard-float
have been added. These options apply to both m68k and ColdFire
targets.
* -mno-short, -mno-bitfield and -mno-rtd are now accepted as negative
versions of -mshort, etc.
* -fforce-addr has been removed. It is now ignored by the compiler.

Other improvements

* ColdFire targets now try to maintain a 4-byte-aligned stack where
possible.
* m68k-uclinux targets now try to avoid situations that lead to the
load-time error: BINFMT_FLAT: reloc outside program.

MIPS

Changes to existing configurations

* libffi and libjava now support all three GNU/Linux ABIs: o32, n32
and n64. Every GNU/Linux configuration now builds these libraries
by default.
* GNU/Linux configurations now generate -mno-shared code unless
overridden by -fpic, -fPIC, -fpie or -fPIE.
* mipsisa32*-linux-gnu configurations now generate hard-float code by
default, just like other mipsisa32* and mips*-linux-gnu
configurations. You can build a soft-float version of any
mips*-linux-gnu configuration by passing --with-float=soft to
configure.
* mips-wrs-vxworks now supports run-time processes (RTPs).

Changes to existing command-line options

* The -march and -mtune options no longer accept 24k as a processor
name. Please use 24kc, 24kf2_1 or 24kf1_1 instead.
* The -march and -mtune options now accept 24kf2_1, 24kef2_1 and
34kf2_1 as synonyms for 24kf, 24kef and 34kf respectively. The
options also accept 24kf1_1, 24kef1_1 and 34kf1_1 as synonyms for
24kx, 24kex and 34kx.

New configurations

GCC now supports the following configurations:
* mipsisa32r2*-linux-gnu*, which generates MIPS32 revision 2 code by
default. Earlier releases also recognized this configuration, but
they treated it in the same way as mipsisa32*-linux-gnu*. Note that
you can customize any mips*-linux-gnu* configuration to a
particular ISA or processor by passing an appropriate --with-arch
option to configure.
* mipsisa*-sde-elf*, which provides compatibility with MIPS
Technologies' SDE toolchains. The configuration uses the SDE
libraries by default, but you can use it like other newlib-based
ELF configurations by passing --with-newlib to configure. It is the
only configuration besides mips64vr*-elf* to build MIPS16 as well
as non-MIPS16 libraries.
* mipsisa*-elfoabi*, which is similar to the general mipsisa*-elf*
configuration, but uses the o32 and o64 ABIs instead of the 32-bit
and 64-bit forms of the EABI.

New processors and application-specific extensions

* Support for the SmartMIPS ASE is available through the new
-msmartmips option.
* Support for revision 2 of the DSP ASE is available through the new
-mdspr2 option. A new preprocessor macro called __mips_dsp_rev
indicates the revision of the ASE in use.
* Support for the 4KS and 74K families of processors is available
through the -march and -mtune options.

Improved support for built-in functions

* GCC can now use load-linked, store-conditional and sync
instructions to implement atomic built-in functions such as
__sync_fetch_and_add. The memory reference must be 4 bytes wide for
32-bit targets and either 4 or 8 bytes wide for 64-bit targets.
* GCC can now use the clz and dclz instructions to implement the
__builtin_ctz and __builtin_ffs families of functions.
* There is a new __builtin___clear_cache function for flushing the
instruction cache. GCC expands this function inline on MIPS32
revision 2 targets, otherwise it calls the function specified by
-mcache-flush-func.

MIPS16 improvements

* GCC can now compile objects that contain a mixture of MIPS16 and
non-MIPS16 code. There are two new attributes, mips16 and nomips16,
for specifying which mode a function should use.
* A new option called -minterlink-mips16 makes non-MIPS16 code
link-compatible with MIPS16 code.
* After many bug fixes, the long-standing MIPS16 -mhard-float support
should now work fairly reliably.
* GCC can now use the MIPS16e save and restore instructions.
* -fsection-anchors now works in MIPS16 mode. MIPS16 code compiled
with -G0 -fsection-anchors is often smaller than code compiled with
-G8. However, please note that you must usually compile all objects
in your application with the same -G option; see the documentation
of -G for details.
* A new option called-mcode-readable specifies which instructions are
allowed to load from the code segment. -mcode-readable=yes is the
default and says that any instruction may load from the code
segment. The other alternatives are -mcode-readable=pcrel, which
says that only PC-relative MIPS16 instructions may load from the
code segment, and -mcode-readable=no, which says that no
instruction may do so. Please see the documentation for more
details, including example uses.

Small-data improvements

There are three new options for controlling small data:
* -mno-extern-sdata, which disables small-data accesses for
externally-defined variables. Code compiled with -Gn
-mno-extern-sdata will be link-compatible with any -G setting
between -G0 and -Gn inclusive.
* -mno-local-sdata, which disables the use of small-data sections for
data that is not externally visible. This option can be a useful
way of reducing small-data usage in less performance-critical parts
of an application.
* -mno-gpopt, which disables the use of the $gp register while still
honoring the -G limit when placing externally-visible data. This
option implies -mno-extern-sdata and -mno-local-sdata and it can be
useful in situations where $gp does not necessarily hold the
expected value.

Miscellaneous improvements

* There is a new option called -mbranch-cost for tweaking the
perceived cost of branches.
* If GCC is configured to use a version of GAS that supports the
.gnu_attribute directive, it will use that directive to record
certain properties of the output code. .gnu_attribute is new to GAS
2.18.
* There are two new function attributes, near and far, for overriding
the command-line setting of -mlong-calls on a function-by-function
basis.
* -mfp64, which previously required a 64-bit target, now works with
MIPS32 revision 2 targets as well. The mipsisa*-elfoabi* and
mipsisa*-sde-elf* configurations provide suitable library support.
* GCC now recognizes the -mdmx and -mmt options and passes them down
to the assembler. It does nothing else with the options at present.

SPU (Synergistic Processor Unit) of the Cell Broadband Engine Architecture
(BEA)

* Support has been added for this new architecture.

RS6000 (POWER/PowerPC)

* Support for the PowerPC 750CL paired-single instructions has been
added with a new powerpc-*-linux*paired* target configuration. It
is enabled by an associated -mpaired option and can be accessed
using new built-in functions.
* Support for auto-detecting architecture and system configuration to
auto-select processor optimization tuning.
* Support for VMX on AIX 5.3 has been added.
* Support for AIX Version 6.1 has been added.

S/390, zSeries and System z9

* Support for the IBM System z9 EC/BC processor (z9 GA3) has been
added. When using the -march=z9-ec option, the compiler will
generate code making use of instructions provided by the decimal
floating point facility and the floating point conversion facility
(pfpo). Besides the instructions used to implement decimal floating
point operations these facilities also contain instructions to move
between general purpose and floating point registers and to modify
and copy the sign-bit of floating point values.
* When the -march=z9-ec option is used the new
-mhard-dfp/-mno-hard-dfp options can be used to specify whether the
decimal floating point hardware instructions will be used or not.
If none of them is given the hardware support is enabled by
default.
* The -mstack-guard option can now be omitted when using stack
checking via -mstack-size in order to let GCC choose a sensible
stack guard value according to the frame size of each function.
* Various changes to improve performance of generated code have been
implemented, including:
+ The condition code set by an add logical with carry
instruction is now available for overflow checks like: a + b +
carry < b.
+ The test data class instruction is now used to implement
sign-bit and infinity checks of binary and decimal floating
point numbers.

SPARC

* Support for the Sun UltraSPARC T2 (Niagara 2) processor has been
added.

Xtensa

* Stack unwinding for exception handling now uses by default a
specialized version of DWARF unwinding. This is not
binary-compatible with the setjmp/longjmp (sjlj) unwinding used for
Xtensa with previous versions of GCC.
* For Xtensa processors that include the Conditional Store option,
the built-in functions for atomic memory access are now implemented
using S32C1I instructions.
* If the Xtensa NSA option is available, GCC will use it to implement
the __builtin_ctz and __builtin_clz functions.

Documentation improvements

* Existing libstdc++ documentation has been edited and restructured
into a single DocBook XML manual. The results can be viewed online
[21]here.

Other significant improvements

* The compiler's --help command-line option has been extended so that
it now takes an optional set of arguments. These arguments restrict
the information displayed to specific classes of command-line
options, and possibly only a subset of those options. It is also
now possible to replace the descriptive text associated with each
displayed option with an indication of its current value, or for
binary options, whether it has been enabled or disabled.
Here are some examples. The following will display all the options
controlling warning messages:
--help=warnings

Whereas this will display all the undocumented, target specific
options:
--help=target,undocumented

This sequence of commands will display the binary optimizations
that are enabled by -O3:
gcc -c -Q -O3 --help=optimizers > /tmp/O3-opts
gcc -c -Q -O2 --help=optimizers > /tmp/O2-opts
diff /tmp/O2-opts /tmp/O3-opts | grep enabled

* The configure options --with-pkgversion and --with-bugurl have been
added. These allow distributors of GCC to include a
distributor-specific string in manuals and --version output and to
specify the URL for reporting bugs in their versions of GCC.

[22]GCC 4.3.1

This is the [23]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.3.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Target Specific Changes

IA-32/x86-64

ABI changes

* Starting with GCC 4.3.1, decimal floating point variables are
aligned to their natural boundaries when they are passed on the
stack for i386.

Command-line changes

* Starting with GCC 4.3.1, the -mcld option has been added to
automatically generate a cld instruction in the prologue of
functions that use string instructions. This option is used for
backward compatibility on some operating systems and can be enabled
by default for 32-bit x86 targets by configuring GCC with the
--enable-cld configure option.

[24]GCC 4.3.2

This is the [25]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.3.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[26]GCC 4.3.3

This is the [27]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.3.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[28]GCC 4.3.4

This is the [29]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.3.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[30]GCC 4.3.5

This is the [31]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.3.5 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[32]GCC 4.3.6

This is the [33]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.3.6 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

For questions related to the use of GCC, please consult these web
pages and the [34]GCC manuals. If that fails, the
[35][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [36][email protected]. All of [37]our lists have public
archives.

Copyright (C) [38]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [39]maintained by the GCC team. Last modified
2025-01-31.

References

1. https://gcc.gnu.org/gcc-4.3/changes.html#4.3.5
2. https://gmplib.org/
3. https://www.mpfr.org/
4. https://gcc.gnu.org/install/prerequisites.html
5. https://gcc.gnu.org/ml/gcc-announce/2001/msg00000.html
6. https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#Warning-Options
7. https://gcc.gnu.org/gcc-4.3/porting_to.html
8. https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
9. https://gcc.gnu.org/gcc-4.3/cxx0x_status.html
10. https://gcc.gnu.org/gcc-4.3/cxx0x_status.html
11. https://gcc.gnu.org/onlinedocs/libstdc++/manual/parallel_mode.html
12. https://gcc.gnu.org/onlinedocs/gfortran/Code-Gen-Options.html#Code-Gen-Options
13. https://gcc.gnu.org/onlinedocs/gfortran/Code-Gen-Options.html#index-g_t_0040code_007bfinit-local-zero_007d-167
14. https://gcc.gnu.org/onlinedocs/gcc-4.3.0/gfortran/GAMMA.html
15. https://gcc.gnu.org/onlinedocs/gcc-4.3.0/gfortran/LGAMMA.html
16. https://gcc.gnu.org/onlinedocs/gfortran/Fortran-Dialect-Options.html
17. https://gcc.gnu.org/onlinedocs/gfortran/BOZ-literal-constants.html
18. https://gcc.gnu.org/gcc-4.3/changes.html#targets
19. https://gcc.gnu.org/gcc-4.3/changes.html#cris
20. https://gcc.gnu.org/gcc-4.3/changes.html#m68k
21. https://gcc.gnu.org/onlinedocs/libstdc++/
22. https://gcc.gnu.org/gcc-4.3/changes.html#GCC4.3.1
23. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.3.1
24. https://gcc.gnu.org/gcc-4.3/changes.html#GCC4.3.2
25. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.3.2
26. https://gcc.gnu.org/gcc-4.3/changes.html#GCC4.3.3
27. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.3.3
28. https://gcc.gnu.org/gcc-4.3/changes.html#GCC4.3.4
29. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.3.4
30. https://gcc.gnu.org/gcc-4.3/changes.html#GCC4.3.5
31. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.3.5
32. https://gcc.gnu.org/gcc-4.3/changes.html#GCC4.3.6
33. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.3.6
34. https://gcc.gnu.org/onlinedocs/
35. mailto:[email protected]
36. mailto:[email protected]
37. https://gcc.gnu.org/lists.html
38. https://www.fsf.org/
39. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.2/index.html

GCC 4.2 Release Series

(This release series is no longer supported.)

May 19, 2008

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 4.2.4.

This release is a bug-fix release, containing fixes for regressions in
GCC 4.2.3 relative to previous releases of GCC.

Release History

GCC 4.2.4
May 19, 2008 ([2]changes)

GCC 4.2.3
February 1, 2008 ([3]changes)

GCC 4.2.2
October 7, 2007 ([4]changes)

GCC 4.2.1
July 18, 2007 ([5]changes)

GCC 4.2.0
May 13, 2007 ([6]changes)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [7]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [8]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [9]GCC project
web site or contact the [10]GCC development mailing list.

To obtain GCC please use [11]our mirror sites or [12]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [13]GCC manuals. If that fails, the
[14][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [15][email protected]. All of [16]our lists have public
archives.

Copyright (C) [17]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [18]maintained by the GCC team. Last modified
2022-10-26.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-4.2/changes.html
3. https://gcc.gnu.org/gcc-4.2/changes.html
4. https://gcc.gnu.org/gcc-4.2/changes.html
5. https://gcc.gnu.org/gcc-4.2/changes.html
6. https://gcc.gnu.org/gcc-4.2/changes.html
7. https://gcc.gnu.org/gcc-4.2/buildstat.html
8. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
9. https://gcc.gnu.org/index.html
10. mailto:[email protected]
11. https://gcc.gnu.org/mirrors.html
12. https://gcc.gnu.org/git.html
13. https://gcc.gnu.org/onlinedocs/
14. mailto:[email protected]
15. mailto:[email protected]
16. https://gcc.gnu.org/lists.html
17. https://www.fsf.org/
18. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.2/changes.html

GCC 4.2 Release Series
Changes, New Features, and Fixes

Caveats

* GCC no longer accepts the -fshared-data option. This option has had
no effect in any GCC 4 release; the targets to which the option
used to apply had been removed before GCC 4.0.

General Optimizer Improvements

* New command-line options specify the possible relationships among
parameters and between parameters and global data. For example,
-fargument-noalias-anything specifies that arguments do not alias
any other storage.
Each language will automatically use whatever option is required by
the language standard. You should not need to use these options
yourself.

New Languages and Language specific improvements

* [1]OpenMP is now supported for the C, C++ and Fortran compilers.
* New command-line options -fstrict-overflow and -Wstrict-overflow
have been added. -fstrict-overflow tells the compiler that it may
assume that the program follows the strict signed overflow
semantics permitted for the language: for C and C++ this means that
the compiler may assume that signed overflow does not occur. For
example, a loop like
for (i = 1; i > 0; i *= 2)

is presumably intended to continue looping until i overflows. With
-fstrict-overflow, the compiler may assume that signed overflow
will not occur, and transform this into an infinite loop.
-fstrict-overflow is turned on by default at -O2, and may be
disabled via -fno-strict-overflow. The -Wstrict-overflow option may
be used to warn about cases where the compiler assumes that signed
overflow will not occur. It takes five different levels:
-Wstrict-overflow=1 to 5. See the [2]documentation for details.
-Wstrict-overflow=1 is enabled by -Wall.
* The new command-line option -fno-toplevel-reorder directs GCC to
emit top-level functions, variables, and asm statements in the same
order that they appear in the input file. This is intended to
support existing code which relies on a particular ordering (for
example, code which uses top-level asm statements to switch
sections). For new code, it is generally better to use function and
variable attributes. The -fno-toplevel-reorder option may be used
for most cases which currently use -fno-unit-at-a-time. The
-fno-unit-at-a-time option will be removed in some future version
of GCC. If you know of a case which requires -fno-unit-at-a-time
which is not fixed by -fno-toplevel-reorder, please open a bug
report.

C family

* The pragma redefine_extname will now macro expand its tokens for
compatibility with SunPRO.
* In the next release of GCC, 4.3, -std=c99 or -std=gnu99 will direct
GCC to handle inline functions as specified in the C99 standard. In
preparation for this, GCC 4.2 will warn about any use of non-static
inline functions in gnu99 or c99 mode. This new warning may be
disabled with the new gnu_inline function attribute or the new
-fgnu89-inline command-line option. Also, GCC 4.2 and later will
define one of the preprocessor macros __GNUC_GNU_INLINE__ or
__GNUC_STDC_INLINE__ to indicate the semantics of inline functions
in the current compilation.
* A new command-line option -Waddress has been added to warn about
suspicious uses of memory addresses as, for example, using the
address of a function in a conditional expression, and comparisons
against the memory address of a string literal. This warning is
enabled by -Wall.

C++

* C++ visibility handling has been overhauled.
Restricted visiblity is propagated from classes to members, from
functions to local statics, and from templates and template
arguments to instantiations, unless the latter has explicitly
declared visibility.
The visibility attribute for a class must come between the
class-key and the name, not after the closing brace.
Attributes are now allowed for enums and elaborated-type-specifiers
that only declare a type.
Members of the anonymous namespace are now local to a particular
translation unit, along with any other declarations which use them,
though they are still treated as having external linkage for
language semantics.
* The (undocumented) extension which permitted templates with default
arguments to be bound to template template parameters with fewer
parameters has been removed. For example:
template <template <typename> class C>
void f(C<double>) {}

template <typename T, typename U = int>
struct S {};

template void f(S<double>);

is no longer accepted by G++. The reason this code is not accepted
is that S is a template with two parameters; therefore, it cannot
be bound to C which has only one parameter.
* The <?, >?, <?=, and >?= operators, deprecated in previous GCC
releases, have been removed.
* The command-line option -fconst-strings, deprecated in previous GCC
releases, has been removed.
* The configure variable enable-__cxa_atexit is now enabled by
default for more targets. Enabling this variable is necessary in
order for static destructors to be executed in the correct order,
but it depends upon the presence of a non-standard C library in the
target library in order to work. The variable is now enabled for
more targets which are known to have suitable C libraries.
* -Wextra will produce warnings for if statements with a semicolon as
the only body, to catch code like:
if (a);
return 1;
return 0;

To suppress the warning in valid cases, use { } instead.
* The C++ front end now also produces strict aliasing warnings when
-fstrict-aliasing -Wstrict-aliasing is in effect.

Runtime Library (libstdc++)

* Added support for TR1 <random>, <complex>, and C compatibility
headers. In addition, a lock-free version of shared_ptr was
contributed as part of Phillip Jordan's Google Summer of Code
project on lock-free containers.
* In association with the Summer of Code work on lock-free
containers, the interface for atomic builtins was adjusted,
creating simpler alternatives for non-threaded code paths. Also,
usage was consolidated and all elements were moved from namespace
std to namespace__gnu_cxx. Affected interfaces are the functions
__exchange_and_add, __atomic_add, and the objects __mutex,
__recursive_mutex, and __scoped_lock.
* Support for versioning weak symbol names via namespace association
was added. However, as this changes the names of exported symbols,
this is turned off by default in the current ABI. Intrepid users
can enable this feature by using
--enable-symvers=gnu-versioned-namespace during configuration.
* Revised, simplified, and expanded policy-based associative
containers, including data types for tree and trie forms
(basic_tree, tree, trie), lists (list_update), and both
collision-chaining and probing hash-based containers
(basic_hash_table, cc_hash_table, gp_hash_table). More details per
the [3]documentation.
* The implementation of the debug mode was modified, whereby the
debug namespaces were nested inside of namespace std and namespace
__gnu_cxx in order to resolve some long standing corner cases
involving name lookup. Debug functionality from the policy-based
data structures was consolidated and enabled with the single macro,
_GLIBCXX_DEBUG. See PR 26142 for more information.
* Added extensions for type traits: __conditional_type,
__numeric_traits, __add_unsigned, __removed_unsigned, __enable_if.
* Added a typelist implementation for compile-time meta-programming.
Elements for typelist construction and operation can be found
within namespace __gnu_cxx::typelist.
* Added a new allocator, __gnu_cxx::throw_allocator, for testing
exception-safety.
* Enabled library-wide visibility control, allowing -fvisibility to
be used.
* Consolidated all nested namespaces and the conversion of
__gnu_internal implementation-private details to anonymous
namespaces whenever possible.
* Implemented LWG resolutions DR 431 and DR 538.

Fortran

* Support for allocatable components has been added (TR 15581 and
Fortran 2003).
* Support for the Fortran 2003 streaming IO extension has been added.
* The GNU Fortran compiler now uses 4-byte record markers by default
for unformatted files to be compatible with g77 and most other
compilers. The implementation allows for records greater than 2 GB
and is compatible with several other compilers. Older versions of
gfortran used 8-byte record markers by default (on most systems).
In order to change the length of the record markers, e.g. to read
unformatted files created by older gfortran versions, the
[4]-frecord-marker=8 option can be used.

Java (GCJ)

* A new command-line option -static-libgcj has been added for targets
that use a linker compatible with GNU Binutils. As its name
implies, this causes libgcj to be linked statically. In some cases
this causes the resulting executable to start faster and use less
memory than if the shared version of libgcj were used. However
caution should be used as it can also cause essential parts of the
library to be omitted. Some of these issues are discussed in:
[5]https://gcc.gnu.org/wiki/Statically_linking_libgcj
* fastjar is no longer bundled with GCC. To build libgcj, you will
need either InfoZIP (both zip and unzip) or an external jar
program. In the former case, the GCC build will install a jar shell
script that is based on InfoZIP and provides the same functionality
as fastjar.

[6]New Targets and Target Specific Improvements

IA-32/x86-64

* -mtune=generic can now be used to generate code running well on
common x86 chips. This includes AMD Athlon, AMD Opteron, Intel
Pentium-M, Intel Pentium 4 and Intel Core 2.
* -mtune=native and -march=native will produce code optimized for the
host architecture as detected using the cpuid instruction.
* Added a new command-line option -fstackrealign and and
__attribute__ ((force_align_arg_pointer)) to realign the stack at
runtime. This allows functions compiled with a vector-aligned stack
to be invoked from legacy objects that keep only word-alignment.

SPARC

* The default CPU setting has been changed from V7 to V9 in 32-bit
mode on Solaris 7 and above. This is already the case in 64-bit
mode. It can be overridden by specifying --with-cpu at configure
time.
* Back-end support of built-in functions for atomic memory access has
been implemented.
* Support for the Sun UltraSPARC T1 (Niagara) processor has been
added.

M32C

* Various bug fixes have made some functions (notably, functions
returning structures) incompatible with previous releases.
Recompiling all libraries is recommended. Note that code quality
has considerably improved since 4.1, making a recompile even more
beneficial.

MIPS

* Added support for the Broadcom SB-1A core.

IA-64

* Added support for IA-64 data and control speculation. By default
speculation is enabled only during second scheduler pass. A number
of machine flags was introduced to control the usage of speculation
for both scheduler passes.

HPPA

* Added Java language support (libffi and libjava) for 32-bit HP-UX
11 target.

[7]Obsolete Systems

Documentation improvements

PDF Documentation

* A make pdf target has been added to the top-level makefile,
enabling automated production of PDF documentation files.
(Front-ends external to GCC should modify their Make-lang.in file
to add a lang.pdf: target.)

Other significant improvements

Build system improvements

* All the components of the compiler are now bootstrapped by default.
This improves the resilience to bugs in the system compiler or
binary compatibility problems, as well as providing better testing
of GCC 4.2 itself. In addition, if you build the compiler from a
combined tree, the assembler, linker, etc. will also be
bootstrapped (i.e. built with themselves).
You can disable this behavior, and go back to the pre-GCC 4.2 set
up, by configuring GCC with --disable-bootstrap.
* The rules that configure follows to find target tools resemble more
closely the locations that the built compiler will search. In
addition, you can use the new configure option --with-target-tools
to specify where to find the target tools used during the build,
without affecting what the built compiler will use.
This can be especially useful when building packages of GCC. For
example, you may want to build GCC with GNU as or ld, even if the
resulting compiler to work with the native assembler and linker. To
do so, you can use --with-target-tools to point to the native
tools.

Incompatible changes to the build system

* Front-ends external to GCC should modify their Make-lang.in file to
replace double-colon rules (e.g. dvi::) with normal rules (like
lang.dvi:). Front-end makefile hooks do not use double-colon rules
anymore.
* Up to GCC 4.1, a popular way to specify the target tools used
during the build was to create directories named gas, binutils,
etc. in the build tree, and create links to the tools from there.
This does not work any more when the compiler is bootstrapped. The
new configure option --with-target-tools provides a better way to
achieve the same effect, and works for all native and cross
settings.

For questions related to the use of GCC, please consult these web
pages and the [8]GCC manuals. If that fails, the
[9][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [10][email protected]. All of [11]our lists have public
archives.

Copyright (C) [12]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [13]maintained by the GCC team. Last modified
2025-01-31.

References

1. https://gcc.gnu.org/projects/gomp/
2. https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
3. https://gcc.gnu.org/onlinedocs/libstdc++/ext/pb_ds/index.html
4. https://gcc.gnu.org/onlinedocs/gfortran/Runtime-Options.html
5. https://gcc.gnu.org/wiki/Statically_linking_libgcj
6. https://gcc.gnu.org/gcc-4.2/changes.html#targets
7. https://gcc.gnu.org/gcc-4.2/changes.html#obsolete_systems
8. https://gcc.gnu.org/onlinedocs/
9. mailto:[email protected]
10. mailto:[email protected]
11. https://gcc.gnu.org/lists.html
12. https://www.fsf.org/
13. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.1/index.html

GCC 4.1 Release Series

(This release series is no longer supported.)

February 13, 2007

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 4.1.2.

This release is a bug-fix release, containing fixes for regressions in
GCC 4.1.1 relative to previous releases of GCC.

Release History

GCC 4.1.2
February 13, 2007 ([2]changes)

GCC 4.1.1
May 24, 2006 ([3]changes)

GCC 4.1.0
February 28, 2006 ([4]changes)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [5]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [6]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [7]GCC project
web site or contact the [8]GCC development mailing list.

To obtain GCC please use [9]our mirror sites or [10]our version control
system.

For questions related to the use of GCC, please consult these web
pages and the [11]GCC manuals. If that fails, the
[12][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [13][email protected]. All of [14]our lists have public
archives.

Copyright (C) [15]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [16]maintained by the GCC team. Last modified
2022-10-26.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-4.1/changes.html#4.1.2
3. https://gcc.gnu.org/gcc-4.1/changes.html
4. https://gcc.gnu.org/gcc-4.1/changes.html
5. https://gcc.gnu.org/gcc-4.1/buildstat.html
6. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
7. https://gcc.gnu.org/index.html
8. mailto:[email protected]
9. https://gcc.gnu.org/mirrors.html
10. https://gcc.gnu.org/git.html
11. https://gcc.gnu.org/onlinedocs/
12. mailto:[email protected]
13. mailto:[email protected]
14. https://gcc.gnu.org/lists.html
15. https://www.fsf.org/
16. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.1/changes.html

GCC 4.1 Release Series
Changes, New Features, and Fixes

The latest release in the 4.1 release series is [1]GCC 4.1.2.

Caveats

General Optimizer Improvements

* GCC now has infrastructure for inter-procedural optimizations and
the following inter-procedural optimizations are implemented:
+ Profile guided inlining. When doing profile feedback guided
optimization, GCC can now use the profile to make better
informed decisions on whether inlining of a function is
profitable or not. This means that GCC will no longer inline
functions at call sites that are not executed very often, and
that functions at hot call sites are more likely to be
inlined.
A new parameter min-inline-recursive-probability is also now
available to throttle recursive inlining of functions with
small average recursive depths.
+ Discovery of pure and const functions, a form of side-effects
analysis. While older GCC releases could also discover such
special functions, the new IPA-based pass runs earlier so that
the results are available to more optimizers. The pass is also
simply more powerful than the old one.
+ Analysis of references to static variables and type escape
analysis, also forms of side-effects analysis. The results of
these passes allow the compiler to be less conservative about
call-clobbered variables and references. This results in more
redundant loads being eliminated and in making static
variables candidates for register promotion.
+ Improvement of RTL-based alias analysis. The results of type
escape analysis are fed to the RTL type-based alias analyzer,
allowing it to disambiguate more memory references.
+ Interprocedural constant propagation and function versioning.
This pass looks for functions that are always called with the
same constant value for one or more of the function arguments,
and propagates those constants into those functions.
+ GCC will now eliminate static variables whose usage was
optimized out.
+ -fwhole-program --combine can now be used to make all
functions in program static allowing whole program
optimization. As an exception, the main function and all
functions marked with the new externally_visible attribute are
kept global so that programs can link with runtime libraries.
* GCC can now do a form of partial dead code elimination (PDCE) that
allows code motion of expressions to the paths where the result of
the expression is actually needed. This is not always a win, so the
pass has been limited to only consider profitable cases. Here is an
example:
int foo (int *, int *);
int
bar (int d)
{
int a, b, c;
b = d + 1;
c = d + 2;
a = b + c;
if (d)
{
foo (&b, &c);
a = b + c;
}
printf ("%d\n", a);
}

The a = b + c can be sunk to right before the printf. Normal code
sinking will not do this, it will sink the first one above into the
else-branch of the conditional jump, which still gives you two
copies of the code.
* GCC now has a value range propagation pass. This allows the
compiler to eliminate bounds checks and branches. The results of
the pass can also be used to accurately compute branch
probabilities.
* The pass to convert PHI nodes to straight-line code (a form of
if-conversion for GIMPLE) has been improved significantly. The two
most significant improvements are an improved algorithm to
determine the order in which the PHI nodes are considered, and an
improvement that allow the pass to consider if-conversions of basic
blocks with more than two predecessors.
* Alias analysis improvements. GCC can now differentiate between
different fields of structures in Tree-SSA's virtual operands form.
This lets stores/loads from non-overlapping structure fields not
conflict. A new algorithm to compute points-to sets was contributed
that can allows GCC to see now that p->a and p->b, where p is a
pointer to a structure, can never point to the same field.
* Various enhancements to auto-vectorization:
+ Incrementally preserve SSA form when vectorizing.
+ Incrementally preserve loop-closed form when vectorizing.
+ Improvements to peeling for alignment: generate better code
when the misalignment of an access is known at compile time,
or when different accesses are known to have the same
misalignment, even if the misalignment amount itself is
unknown.
+ Consider dependence distance in the vectorizer.
+ Externalize generic parts of data reference analysis to make
this analysis available to other passes.
+ Vectorization of conditional code.
+ Reduction support.
* GCC can now partition functions in sections of hot and cold code.
This can significantly improve performance due to better
instruction cache locality. This feature works best together with
profile feedback driven optimization.
* A new pass to avoid saving of unneeded arguments to the stack in
vararg functions if the compiler can prove that they will not be
needed.
* Transition of basic block profiling to tree level implementation
has been completed. The new implementation should be considerably
more reliable (hopefully avoiding profile mismatch errors when
using -fprofile-use or -fbranch-probabilities) and can be used to
drive higher level optimizations, such as inlining.
The -ftree-based-profiling command-line option was removed and
-fprofile-use now implies disabling old RTL level loop optimizer
(-fno-loop-optimize). Speculative prefetching optimization
(originally enabled by -fspeculative-prefetching) was removed.

New Languages and Language specific improvements

C and Objective-C

* The old Bison-based C and Objective-C parser has been replaced by a
new, faster hand-written recursive-descent parser.

Ada

* The build infrastructure for the Ada runtime library and tools has
been changed to be better integrated with the rest of the build
infrastructure of GCC. This should make doing cross builds of Ada a
bit easier.

[2]C++

* ARM-style name-injection of friend declarations is no longer the
default. For example:
struct S {
friend void f();
};

void g() { f(); }
will not be accepted; instead a declaration of f will need to be
present outside of the scope of S. The new -ffriend-injection
option will enable the old behavior.
* The (undocumented) extension which permitted templates with default
arguments to be bound to template template parameters with fewer
parameters has been deprecated, and will be removed in the next
major release of G++. For example:
template <template <typename> class C>
void f(C<double>) {}

template <typename T, typename U = int>
struct S {};

template void f(S<double>);

makes use of the deprecated extension. The reason this code is not
valid ISO C++ is that S is a template with two parameters;
therefore, it cannot be bound to C which has only one parameter.

Runtime Library (libstdc++)

* Optimization work:
+ A new implementation of std::search_n is provided, better
performing in case of random access iterators.
+ Added further efficient specializations of istream functions,
i.e., character array and string extractors.
+ Other smaller improvements throughout.
* Policy-based associative containers, designed for high-performance,
flexibility and semantic safety are delivered in ext/pb_assoc.
* A versatile string class, __gnu_cxx::__versa_string, providing
facilities conforming to the standard requirements for
basic_string, is delivered in <ext/vstring.h>. In particular:
+ Two base classes are provided: the default one avoids
reference counting and is optimized for short strings; the
alternate one, still uses it while improving in a few low
level areas (e.g., alignment). See vstring_fwd.h for some
useful typedefs.
+ Various algorithms have been rewritten (e.g., replace), the
code streamlined and simple optimizations added.
+ Option 3 of DR 431 is implemented for both available bases,
thus improving the support for stateful allocators.
* As usual, many bugs have been fixed (e.g., libstdc++/13583,
libstdc++/23953) and LWG resolutions put into effect for the first
time (e.g., DR 280, DR 464, N1780 recommendations for DR 233, TR1
Issue 6.19). The implementation status of TR1 is now tracked in the
docs in tr1.html.

Objective-C++

* A new language front end for Objective-C++ has been added. This
language allows users to mix the object oriented features of
Objective-C with those of C++.

Java (GCJ)

* Core library (libgcj) updates based on GNU Classpath 0.15 - 0.19
features (plus some 0.20 bug-fixes)
+ Networking
o The java.net.HttpURLConnection implementation no longer
buffers the entire response body in memory. This means
that response bodies larger than available memory can now
be handled.
+ (N)IO
o NIO FileChannel.map implementation, fast bulk put
implementation for DirectByteBuffer (speeds up this
method 10x).
o FileChannel.lock() and FileChannel.force() implemented.
+ XML
o gnu.xml fix for nodes created outside a namespace
context.
o Add support for output indenting and
cdata-section-elements output instruction in
xml.transform.
o xml.xpath corrections for cases where elements/attributes
might have been created in non-namespace-aware mode.
Corrections to handling of XSL variables and minor
conformance updates.
+ AWT
o GNU JAWT implementation, the AWT Native Interface, which
allows direct access to native screen resources from
within a Canvas's paint method. GNU Classpath Examples
comes with a Demo, see libjava/classpath/examples/README.
o awt.datatransfer updated to 1.5 with support for
FlavorEvents. The gtk+ awt peers now allow copy/paste of
text, images, URIs/files and serialized objects with
other applications and tracking clipboard change events
with gtk+ 2.6 (for gtk+ 2.4 only text and serialized
objects are supported). A GNU Classpath Examples
datatransfer Demo was added to show the new
functionality.
o Split gtk+ awt peers event handling in two threads and
improve gdk lock handling (solves several awt lock ups).
o Speed up awt Image loading.
o Better gtk+ scrollbar peer implementation when using gtk+
>= 2.6.
o Handle image loading errors correctly for gdkpixbuf and
MediaTracker.
o Better handle GDK lock. Properly prefix gtkpeer native
functions (cp_gtk).
o GdkGraphics2D has been updated to use Cairo 0.5.x or
higher.
o BufferedImage and GtkImage rewrites. All image drawing
operations should now work correctly (flipping requires
gtk+ >= 2.6)
o When gtk+ 2.6 or higher is installed the default log
handler will produce stack traces whenever a WARNING,
CRITICAL or ERROR message is produced.
+ Free Swing
o The RepaintManager has been reworked for more efficient
painting, especially for large GUIs.
o The layout manager OverlayLayout has been implemented,
the BoxLayout has been rewritten to make use of the
SizeRequirements utility class and caching for more
efficient layout.
o Improved accessibility support.
o Significant progress has been made in the implementation
of the javax.swing.plaf.metal package, with most UI
delegates in a working state now. Please test this with
your own applications and provide feedback that will help
us to improve this package.
o The GUI demo (gnu.classpath.examples.swing.Demo) has been
extended to highlight various features in our Free Swing
implementation. And it includes a look and feel switcher
for Metal (default), Ocean and GNU themes.
o The javax.swing.plaf.multi package is now implemented.
o Editing and several key actions for JTree and JTable were
implemented.
o Lots of icons and look and feel improvements for Free
Swing basic and metal themes were added. Try running the
GNU Classpath Swing Demo in examples
(gnu.classpath.examples.swing.Demo) with:
-Dswing.defaultlaf=javax.swing.plaf.basic.BasicLookAndFee
l or
-Dswing.defaultlaf=javax.swing.plaf.metal.MetalLookAndFee
l
o Start of styled text capabilites for java.swing.text.
o DefaultMutableTreeNode pre-order, post-order, depth-first
and breadth-first traversal enumerations implemented.
o JInternalFrame colors and titlebar draw properly.
o JTree is working up to par (icons, selection and keyboard
traversal).
o JMenus were made more compatible in visual and
programmatic behavior.
o JTable changeSelection and multiple selections
implemented.
o JButton and JToggleButton change states work properly
now.
o JFileChooser fixes.
o revalidate() and repaint() fixes which make Free Swing
much more responsive.
o MetalIconFactory implemented.
o Free Swing Top-Level Compatibility. JFrame, JDialog,
JApplet, JInternalFrame, and JWindow are now 1.5
compatible in the sense that you can call add() and
setLayout() directly on them, which will have the same
effect as calling getContentPane().add() and
getContentPane().setLayout().
o The JTree interface has been completed. JTrees now
recognizes mouse clicks and selections work.
o BoxLayout works properly now.
o Fixed GrayFilter to actually work.
o Metal SplitPane implemented.
o Lots of Free Swing text and editor stuff work now.
+ Free RMI and Corba
o Andrew Watson, Vice President and Technical Director of
the Object Management Group, has officially assigned us
20 bit Vendor Minor Code Id: 0x47430 ("GC") that will
mark remote classpath-specific system exceptions.
Obtaining the VMCID means that GNU Classpath now is a
recogniseable type of node in a highly interoperable
CORBA world.
o GNU Classpath now includes the first working draft to
support the RMI over IIOP protocol. The current
implementation is capable of remote invocations,
transferring various Serializables and Externalizables
via RMI-IIOP protocol. It can flatten graphs and, at
least for the simple cases, is interoperable with 1.5
JDKs.
o org.omg.PortableInterceptor and related functionality in
other packages is now implemented:
# The sever and client interceptors work as required
since 1.4.
# The IOR interceptor works as needed for 1.5.
o The org.omg.DynamicAny package is completed and passes
the prepared tests.
o The Portable Object Adapter should now support the output
of the recent IDL to java compilers. These compilers now
generate servants and not CORBA objects as before, making
the output depend on the existing POA implementation.
Completing POA means that such code can already be tried
to run on Classpath. Our POA is tested for the following
usager scenarios:
# POA converts servant to the CORBA object.
# Servant provides to the CORBA object.
# POA activates new CORBA object with the given Object
Id (byte array) that is later accessible for the
servant.
# During the first call, the ServantActivator provides
servant for this and all subsequent calls on the
current object.
# During each call, the ServantLocator provides
servant for this call only.
# ServantLocator or ServantActivator forwards call to
another server.
# POA has a single servant, responsible for all
objects.
# POA has a default servant, but some objects are
explicitly connected to they specific servants.
The POA is verified using tests from the former
cost.omg.org.
o The CORBA implementation is now a working prototype that
should support features up to 1.3 inclusive. We invite
groups writing CORBA dependent applications to try
Classpath implementation, reporting any possible bugs.
The CORBA prototype is interoperable with Sun's
implementation v 1.4, transferring object references,
primitive types, narrow and wide strings, arrays,
structures, trees, abstract interfaces and value types
(feature of CORBA 2.3) between these two platforms.
Remote exceptions are transferred and handled correctly.
The stringified object references (IORs) from various
sources are parsed as required. The transient (for
current session) and permanent (till jre restart)
redirections work. Both Little and Big Endian encoded
messages are accepted. The implementation is verified
using tests from the former cost.omg.org. The current
release includes working examples (see the examples
directory), demonstrating the client-server
communication, using either CORBA Request or IDL-based
stub (usually generated by a IDL to java compiler). These
examples also show how to use the Classpath CORBA naming
service. The IDL to java compiler is not yet written, but
as our library must be compatible, it naturally accepts
the output of other idlj implementations.
+ Misc
o Updated TimeZone data against Olson tzdata2005l.
o Make zip and jar packages UTF-8 clean.
o "native" code builds and compiles (warning free) on
Darwin and Solaris.
o java.util.logging.FileHandler now rotates files.
o Start of a generic JDWP framework in gnu/classpath/jdwp.
This is unfinished, but feedback (at [email protected])
from runtime hackers is greatly appreciated. Although
most of the work is currently being done around gcj/gij
we want this framework to be as VM neutral as possible.
Early design is described in:
[3]https://gcc.gnu.org/ml/java/2005-05/msg00260.html
o QT4 AWT peers, enable by giving configure
--enable-qt-peer. Included, but not ready for production
yet. They are explicitly disabled and not supported. But
if you want to help with the development of these new
features we are interested in feedback. You will have to
explicitly enable them to try them out (and they will
most likely contain bugs).
o Documentation fixes all over the place. See
[4]https://developer.classpath.org/doc/

[5]New Targets and Target Specific Improvements

IA-32/x86-64

* The x86-64 medium model (that allows building applications whose
data segment exceeds 4GB) was redesigned to match latest ABI draft.
New implementation split large datastructures into separate segment
improving performance of accesses to small datastructures and also
allows linking of small model libraries into medium model programs
as long as the libraries are not accessing the large datastructures
directly. Medium model is also supported in position independent
code now.
The ABI change results in partial incompatibility among medium
model objects. Linking medium model libraries (or objects) compiled
with new compiler into medium model program compiled with older
will likely result in exceeding ranges of relocations.
Binutils 2.16.91 or newer are required for compiling medium model
now.

RS6000 (POWER/PowerPC)

* The AltiVec vector primitives in <altivec.h> are now implemented in
a way that puts a smaller burden on the preprocessor, instead
processing the "overloading" in the front ends. This should benefit
compilation speed on AltiVec vector code.
* AltiVec initializers now are generated more efficiently.
* The popcountb instruction available on POWER5 now is generated.
* The floating point round to integer instructions available on
POWER5+ now is generated.
* Floating point divides can be synthesized using the floating point
reciprocal estimate instructions.
* Double precision floating point constants are initialized as single
precision values if they can be represented exactly.

S/390, zSeries and System z9

* Support for the IBM System z9 109 processor has been added. When
using the -march=z9-109 option, the compiler will generate code
making use of instructions provided by the extended immediate
facility.
* Support for 128-bit IEEE floating point has been added. When using
the -mlong-double-128 option, the compiler will map the long double
data type to 128-bit IEEE floating point. Using this option
constitutes an ABI change, and requires glibc support.
* Various changes to improve performance of generated code have been
implemented, including:
+ In functions that do not require a literal pool, register %r13
(which is traditionally reserved as literal pool pointer), can
now be freely used for other purposes by the compiler.
+ More precise tracking of register use allows the compiler to
generate more efficient function prolog and epilog code in
certain cases.
+ The SEARCH STRING, COMPARE LOGICAL STRING, and MOVE STRING
instructions are now used to implement C string functions.
+ The MOVE CHARACTER instruction with single byte overlap is now
used to implement the memset function with non-zero fill byte.
+ The LOAD ZERO instructions are now used where appropriate.
+ The INSERT CHARACTERS UNDER MASK, STORE CHARACTERS UNDER MASK,
and INSERT IMMEDIATE instructions are now used more frequently
to optimize bitfield operations.
+ The BRANCH ON COUNT instruction is now used more frequently.
In particular, the fact that a loop contains a subroutine call
no longer prevents the compiler from using this instruction.
+ The compiler is now aware that all shift and rotate
instructions implicitly truncate the shift count to six bits.
* Back-end support for the following generic features has been
implemented:
+ The full set of [6]built-in functions for atomic memory
access.
+ The -fstack-protector feature.
+ The optimization pass avoiding unnecessary stores of incoming
argument registers in functions with variable argument list.

SPARC

* The default code model in 64-bit mode has been changed from
Medium/Anywhere to Medium/Middle on Solaris.
* TLS support is disabled by default on Solaris prior to release 10.
It can be enabled on TLS-capable Solaris 9 versions (4/04 release
and later) by specifying --enable-tls at configure time.

MorphoSys

* Support has been added for this new architecture.

[7]Obsolete Systems

Documentation improvements

Other significant improvements

* GCC can now emit code for protecting applications from
stack-smashing attacks. The protection is realized by buffer
overflow detection and reordering of stack variables to avoid
pointer corruption.
* Some built-in functions have been fortified to protect them against
various buffer overflow (and format string) vulnerabilities.
Compared to the mudflap bounds checking feature, the safe builtins
have far smaller overhead. This means that programs built using
safe builtins should not experience any measurable slowdown.

[8]GCC 4.1.2

This is the [9]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.1.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

When generating code for a shared library, GCC now recognizes that
global functions may be replaced when the program runs. Therefore, it
is now more conservative in deducing information from the bodies of
functions. For example, in this example:
void f() {}
void g() {
try { f(); }
catch (...) {
cout << "Exception";
}
}

G++ would previously have optimized away the catch clause, since it
would have concluded that f cannot throw exceptions. Because users may
replace f with another function in the main body of the program, this
optimization is unsafe, and is no longer performed. If you wish G++ to
continue to optimize as before, you must add a throw() clause to the
declaration of f to make clear that it does not throw exceptions.

For questions related to the use of GCC, please consult these web
pages and the [10]GCC manuals. If that fails, the
[11][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [12][email protected]. All of [13]our lists have public
archives.

Copyright (C) [14]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [15]maintained by the GCC team. Last modified
2025-01-31.

References

1. https://gcc.gnu.org/gcc-4.1/changes.html#4.1.2
2. https://gcc.gnu.org/gcc-4.1/changes.html#cplusplus
3. https://gcc.gnu.org/ml/java/2005-05/msg00260.html
4. https://developer.classpath.org/doc/
5. https://gcc.gnu.org/gcc-4.1/changes.html#targets
6. https://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
7. https://gcc.gnu.org/gcc-4.1/changes.html#obsolete_systems
8. https://gcc.gnu.org/gcc-4.1/changes.html#GCC4.1.2
9. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.1.2
10. https://gcc.gnu.org/onlinedocs/
11. mailto:[email protected]
12. mailto:[email protected]
13. https://gcc.gnu.org/lists.html
14. https://www.fsf.org/
15. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.0/index.html

GCC 4.0 Release Series

(This release series is no longer supported.)

January 31, 2007

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 4.0.4.

This release is a bug-fix release, containing fixes for regressions in
GCC 4.0.3 relative to previous releases of GCC.

Release History

GCC 4.0.4
January 31, 2007 ([2]changes)

GCC 4.0.3
March 10, 2006 ([3]changes)

GCC 4.0.2
September 28, 2005 ([4]changes)

GCC 4.0.1
July 7, 2005 ([5]changes)

GCC 4.0.0
April 20, 2005 ([6]changes)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [7]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [8]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [9]GCC project
web site or contact the [10]GCC development mailing list.

To obtain GCC please use [11]our mirror sites, or [12]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [13]GCC manuals. If that fails, the
[14][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [15][email protected]. All of [16]our lists have public
archives.

Copyright (C) [17]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [18]maintained by the GCC team. Last modified
2022-10-26.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-4.0/changes.html#4.0.4
3. https://gcc.gnu.org/gcc-4.0/changes.html#4.0.3
4. https://gcc.gnu.org/gcc-4.0/changes.html#4.0.2
5. https://gcc.gnu.org/gcc-4.0/changes.html#4.0.1
6. https://gcc.gnu.org/gcc-4.0/changes.html
7. https://gcc.gnu.org/gcc-4.0/buildstat.html
8. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
9. https://gcc.gnu.org/index.html
10. mailto:[email protected]
11. https://gcc.gnu.org/mirrors.html
12. https://gcc.gnu.org/git.html
13. https://gcc.gnu.org/onlinedocs/
14. mailto:[email protected]
15. mailto:[email protected]
16. https://gcc.gnu.org/lists.html
17. https://www.fsf.org/
18. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-4.0/changes.html

GCC 4.0 Release Series
Changes, New Features, and Fixes

The latest release in the 4.0 release series is [1]GCC 4.0.4.

Caveats

* GCC now generates location lists by default when compiling with
debug info and optimization.
+ GDB 6.0 and older crashes when it sees location lists. GDB 6.1
or later is needed to debug binaries containing location
lists.
+ When you are trying to view a value of a variable in a part of
a function where it has no location (for example when the
variable is no longer used and thus its location was used for
something else) GDB will say that it is not available.
You can disable generating location lists by -fno-var-tracking.
* GCC no longer accepts the -fwritable-strings option. Use named
character arrays when you need a writable string.
* The options -freduce-all-givs and -fmove-all-movables have been
discontinued. They were used to circumvent a shortcoming in the
heuristics of the old loop optimization code with respect to common
Fortran constructs. The new (tree) loop optimizer works differently
and doesn't need those work-arounds.
* The graph-coloring register allocator, formerly enabled by the
option -fnew-ra, has been discontinued.
* -I- has been deprecated. -iquote is meant to replace the need for
this option.
* The MIPS -membedded-pic and -mrnames options have been removed.
* All MIPS targets now require the GNU assembler. In particular, IRIX
configurations can no longer use the MIPSpro assemblers, although
they do still support the MIPSpro linkers.
* The SPARC option -mflat has been removed.
* English-language diagnostic messages will now use Unicode quotation
marks in UTF-8 locales. (Non-English messages already used the
quotes appropriate for the language in previous releases.) If your
terminal does not support UTF-8 but you are using a UTF-8 locale
(such locales are the default on many GNU/Linux systems) then you
should set LC_CTYPE=C in the environment to disable that locale.
Programs that parse diagnostics and expect plain ASCII
English-language messages should set LC_ALL=C. See [2]Markus Kuhn's
explanation of Unicode quotation marks for more information.
* The specs file is no longer installed on most platforms. Most users
will be totally unaffected. However, if you are accustomed to
editing the specs file yourself, you will now have to use the
-dumpspecs option to generate the specs file, and then edit the
resulting file.

General Optimizer Improvements

* The [3]tree ssa branch has been merged. This merge has brought in a
completely new optimization framework based on a higher level
intermediate representation than the existing RTL representation.
Numerous new code transformations based on the new framework are
available in GCC 4.0, including:
+ Scalar replacement of aggregates
+ Constant propagation
+ Value range propagation
+ Partial redundancy elimination
+ Load and store motion
+ Strength reduction
+ Dead store elimination
+ Dead and unreachable code elimination
+ [4]Autovectorization
+ Loop interchange
+ Tail recursion by accumulation
Many of these passes outperform their counterparts from previous
GCC releases.
* [5]Swing Modulo Scheduling (SMS). An RTL level instruction
scheduling optimization intended for loops that perform heavy
computations.

New Languages and Language specific improvements

C family

* The sentinel attribute has been added to GCC. This function
attribute allows GCC to warn when variadic functions such as execl
are not NULL terminated. See the GCC manual for a complete
description of its behavior.
* Given __attribute__((alias("target"))) it is now an error if target
is not a symbol, defined in the same translation unit. This also
applies to aliases created by #pragma weak alias=target. This is
because it's meaningless to define an alias to an undefined symbol.
On Solaris, the native assembler would have caught this error, but
GNU as does not.

C and Objective-C

* The -Wstrict-aliasing=2 option has been added. This warning catches
all unsafe cases, but it may also give a warning for some cases
that are safe.
* The cast-as-lvalue, conditional-expression-as-lvalue and
compound-expression-as-lvalue extensions, which were deprecated in
3.3.4 and 3.4, have been removed.
* The -fwritable-strings option, which was deprecated in 3.4, has
been removed.
* #pragma pack() semantics have been brought closer to those used by
other compilers. This also applies to C++.
* Taking the address of a variable with register storage is invalid
in C. GCC now issues an error instead of a warning.
* Arrays of incomplete element type are invalid in C. GCC now issues
an error for such arrays. Declarations such as extern struct s x[];
(where struct s has not been defined) can be moved after the
definition of struct s. Function parameters declared as arrays of
incomplete type can instead be declared as pointers.

C++

* When compiling without optimizations (-O0), the C++ front end is
much faster than in any previous versions of GCC. Independent
testers have measured speed-ups up to 25% in real-world production
code, compared to the 3.4 family (which was already the fastest
version to date). Upgrading from older versions might show even
bigger improvements.
* ELF visibility attributes can now be applied to a class type, so
that it affects every member function of a class at once, without
having to specify each individually:
class __attribute__ ((visibility("hidden"))) Foo
{
int foo1();
void foo2();
};
The syntax is deliberately similar to the __declspec() system used
by Microsoft Windows based compilers, allowing cross-platform
projects to easily reuse their existing macro system for denoting
exports and imports. By explicitly marking internal classes never
used outside a binary as hidden, one can completely avoid PLT
indirection overheads during their usage by the compiler. You can
find out more about the advantages of this at
[6]https://www.akkadia.org/drepper/dsohowto.pdf
* The -fvisibility-inlines-hidden option has been added which marks
all inlineable functions as having hidden ELF visibility, thus
removing their symbol and typeinfo from the exported symbol table
of the output ELF binary. Using this option can reduce the exported
symbol count of template-heavy code by up to 40% with no code
change at all, thus notably improving link and load times for the
binary as well as a reduction in size of up to 10%. Also, check the
new [7]-fvisibility option.
* The compiler now uses the library interface specified by the [8]C++
ABI for thread-safe initialization of function-scope static
variables. Most users should leave this alone, but embedded
programmers may want to disable this by specifying
-fno-threadsafe-statics for a small savings in code size.
* Taking the address of an explicit register variable is no longer
supported. Note that C++ allows taking the address of variables
with register storage so this will continue to compile with a
warning. For example, assuming that r0 is a machine register:
register int foo asm ("r0");
register int bar;
&foo; // error, no longer accepted
&bar; // OK, with a warning
* G++ has an undocumented extension to virtual function covariancy
rules that allowed the overrider to return a type that was
implicitly convertable to the overridden function's return type.
For instance a function returning void * could be overridden by a
function returning T *. This is now deprecated and will be removed
in a future release.
* The G++ minimum and maximum operators (<? and >?) and their
compound forms (<?=) and >?=) have been deprecated and will be
removed in a future version. Code using these operators should be
modified to use std::min and std::max instead.
* Declaration of nested classes of class templates as friends are
supported:
template <typename T> struct A {
class B {};
};
class C {
template <typename T> friend class A<T>::B;
};
This complements the feature member functions of class templates as
friends introduced in GCC 3.4.0.
* When declaring a friend class using an unqualified name, classes
outside the innermost non-class scope are not searched:
class A;
namespace N {
class B {
friend class A; // Refer to N::A which has not been declared yet
// because name outside namespace N are not searched
friend class ::A; // Refer to ::A
};
}
Hiding the friend name until declaration is still not implemented.
* Friends of classes defined outside their namespace are correctly
handled:
namespace N {
class A;
}
class N::A {
friend class B; // Refer to N::B in GCC 4.0.0
// but ::B in earlier versions of GCC
};

Runtime Library (libstdc++)

* Optimization work:
+ Added efficient specializations of istream functions for char
and wchar_t.
+ Further performance tuning of strings, in particular wrt
single-char append and getline.
+ iter_swap - and therefore most of the mutating algorithms -
now makes an unqualified call to swap when the value_type of
the two iterators is the same.
* A large subset of the features in Technical Report 1 (TR1 for
short) is experimentally delivered (i.e., no guarantees about the
implementation are provided. In particular it is not promised that
the library will remain link-compatible when code using TR1 is
used):
+ General utilities such as reference_wrapper and shared_ptr.
+ Function objects, i.e., result_of, mem_fn, bind, function.
+ Support for metaprogramming.
+ New containers such as tuple, array, unordered_set,
unordered_map, unordered_multiset, unordered_multimap.
* As usual, many bugs have been fixed and LWG resolutions implemented
for the first time (e.g., DR 409).

Java

* In order to prevent naming conflicts with other implementations of
these tools, some GCJ binaries have been renamed:
+ rmic is now grmic,
+ rmiregistry is now grmiregistry, and
+ jar is now fastjar.
In particular, these names were problematic for the jpackage.org
packaging conventions which install symlinks in /usr/bin that point
to the preferred versions of these tools.
* The -findirect-dispatch argument to the compiler now works and
generates code following a new "binary compatibility" ABI. Code
compiled this way follows the binary compatibility rules of the
Java Language Specification.
* libgcj now has support for using GCJ as a JIT, using the
gnu.gcj.jit family of system properties.
* libgcj can now find a shared library corresponding to the bytecode
representation of a class. See the documentation for the new
gcj-dbtool program, and the new gnu.gcj.precompiled.db.path system
property.
* There have been many improvements to the class library. Here are
some highlights:
+ Much more of AWT and Swing exist.
+ Many new packages and classes were added, including
java.util.regex, java.net.URI, javax.crypto,
javax.crypto.interfaces, javax.crypto.spec, javax.net,
javax.net.ssl, javax.security.auth,
javax.security.auth.callback, javax.security.auth.login,
javax.security.auth.x500, javax.security.sasl, org.ietf.jgss,
javax.imageio, javax.imageio.event, javax.imageio.spi,
javax.print, javax.print.attribute,
javax.print.attribute.standard, javax.print.event, and
javax.xml
+ Updated SAX and DOM, and imported GNU JAXP

Fortran

* A new [9]Fortran front end has replaced the aging GNU Fortran 77
front end. The new front end supports Fortran 90 and Fortran 95. It
may not yet be as stable as the old Fortran front end.

Ada

* Ada (with tasking and Zero Cost Exceptions) is now available on
many more targets, including but not limited to: alpha-linux,
hppa-hpux, hppa-linux, powerpc-darwin, powerpc-linux, s390-linux,
s390x-linux, sparc-linux.
* Some of the new Ada 2005 features are now implemented like
Wide_Wide_Character and Ada.Containers.
* Many bugs have been fixed, tools and documentation improved.
* To compile Ada from the sources, install an older working Ada
compiler and then use --enable-languages=ada at configuration time,
since the Ada front end is not currently activated by default. See
the [10]Installing GCC for details.

[11]New Targets and Target Specific Improvements

H8/300

* The frame layout has changed. In the new layout, the prologue of a
function first saves registers and then allocate space for locals,
resulting in an 1% improvement on code size.

IA-32/x86-64 (AMD64)

* The acos, asin, drem, exp10, exp2, expm1, fmod, ilogb, log10,
log1p, log2, logb and tan mathematical builtins (and their float
and long double variants) are now implemented as inline x87
intrinsics when using -ffast-math.
* The ceil, floor, nearbyint, rint and trunc mathematical builtins
(and their float and long double variants) are now implemented as
inline x87 intrinsics when using -ffast-math.
* The x87's fsincos instruction is now used automatically with
-ffast-math when calculating both the sin and cos of the same
argument.
* Instruction selection for multiplication and division by constants
has been improved.

IA-64

* Floating point division, integer division and sqrt are now inlined,
resulting in significant performance improvements on some codes.

MIPS

* Division by zero checks now use conditional traps if the target
processor supports them. This decreases code size by one word per
division operation. The old behavior (branch and break) can be
obtained either at configure time by passing --with-divide=breaks
to configure or at runtime by passing -mdivide-breaks to GCC.
* Support for MIPS64 paired-single instructions has been added. It is
enabled by -mpaired-single and can be accessed using both the
target-independent vector extensions and new MIPS-specific built-in
functions.
* Support for the MIPS-3D ASE has been added. It is enabled by
-mips3d and provides new MIPS-3D-specific built-in functions.
* The -mexplicit-relocs option now supports static n64 code (as is
used, for example, in 64-bit linux kernels). -mexplicit-relocs
should now be feature-complete and is enabled by default when GCC
is configured to use a compatible assembler.
* Support for the NEC VR4130 series has been added. This support
includes the use of VR-specific instructions and a new VR4130
scheduler. Full VR4130 support can be selected with -march=vr4130
while code for any ISA can be tuned for the VR4130 using
-mtune=vr4130. There is also a new -mvr4130-align option that
produces better schedules at the cost of increased code size.
* Support for the Broadcom SB-1 has been extended. There is now an
SB-1 scheduler as well as support for the SB-1-specific
paired-single instructions. Full SB-1 support can be selected with
-march=sb1 while code for any ISA can be optimized for the SB-1
using -mtune=sb1.
* The compiler can now work around errata in R4000, R4400, VR4120 and
VR4130 processors. These workarounds are enabled by -mfix-r4000,
-mfix-r4400, -mfix-vr4120 and -mfix-vr4130 respectively. The VR4120
and VR4130 workarounds need binutils 2.16 or above.
* IRIX shared libraries are now installed into the standard library
directories: o32 libraries go into lib/, n32 libraries go into
lib32/ and n64 libraries go into lib64/.
* The compiler supports a new -msym32 option. It can be used to
optimize n64 code in which all symbols are known to have 32-bit
values.

S/390 and zSeries

* New command-line options help to generate code intended to run in
an environment where stack space is restricted, e.g. Linux kernel
code:
+ -mwarn-framesize and -mwarn-dynamicstack trigger compile-time
warnings for single functions that require large or dynamic
stack frames.
+ -mstack-size and -mstack-guard generate code that checks for
stack overflow at run time.
+ -mpacked-stack generates code that reduces the stack frame
size of many functions by reusing unneeded parts of the stack
bias area.
* The -msoft-float option now ensures that generated code never
accesses floating point registers.
* The s390x-ibm-tpf target now fully supports C++, including
exceptions and threads.
* Various changes to improve performance of the generated code have
been implemented, including:
+ GCC now uses sibling calls where possible.
+ Condition code handling has been optimized, allowing GCC to
omit redundant comparisons in certain cases.
+ The cost function guiding many optimizations has been refined
to more accurately represent the z900 and z990 processors.
+ The ADD LOGICAL WITH CARRY and SUBTRACT LOGICAL WITH BORROW
instructions are now used to avoid conditional branches in
certain cases.
+ The back end now uses the LEGITIMIZE_RELOAD_ADDRESS feature to
optimize address arithmetic required to access large stack
frames.
+ GCC now makes more efficient use of memory-to-memory type
instructions (MVC, CLC, ...).
+ More precise tracking of special register use allows better
instruction scheduling, in particular of the function prologue
and epilogue sequences.
+ The Java front end now generates inline code to implement
integer division, instead of calling library routines.

SPARC

* The options -mv8, -msparclite, -mcypress, -msupersparc, -mf930 and
-mf934 have been removed. They have been replaced with -mcpu=xxx.
* The internal model used to estimate the relative cost of each
instruction has been updated. It is expected to give better results
on recent UltraSPARC processors.
* Code generation for function prologues and epilogues has been
improved, resulting in better scheduling and allowing multiple exit
points in functions.
* Support for Sun's Visual Instruction Set (VIS) has been enhanced.
It is enabled by -mvis and provides new built-in functions for VIS
instructions on UltraSPARC processors.
* The option -mapp-regs has been turned on by default on Solaris too.

NetWare

* Novell NetWare (on ix86, no other hardware platform was ever really
supported by this OS) has been re-enabled and the ABI supported by
GCC has been brought into sync with that of MetroWerks CodeWarrior
(the ABI previously supported was that of some Unix systems, which
NetWare never tried to support).

[12]Obsolete Systems

Support for a number of older systems has been declared obsolete in GCC
4.0. Unless there is activity to revive them, the next release of GCC
will have their sources permanently removed.

All GCC ports for the following processor architectures have been
declared obsolete:
* Intel i860
* Ubicom IP2022
* National Semiconductor NS32K (ns32k)
* Texas Instruments TMS320C[34]x

Also, those for some individual systems have been obsoleted:
* SPARC family
+ SPARClite-based systems (sparclite-*-coff, sparclite-*-elf,
sparc86x-*-elf)
+ OpenBSD 32-bit (sparc-*-openbsd*)

Documentation improvements

Other significant improvements

* Location lists are now generated by default when compiling with
debug info and optimization. Location lists provide more accurate
debug info about locations of variables and they allow debugging
code compiled with -fomit-frame-pointer.
* The -fvisibility option has been added which allows the default ELF
visibility of all symbols to be set per compilation and the new
#pragma GCC visibility preprocessor command allows the setting of
default ELF visibility for a region of code. Using
-fvisibility=hidden especially in combination with the new
-fvisibility-inlines-hidden can yield substantial improvements in
output binary quality including avoiding PLT indirection overheads,
reduction of the exported symbol count by up to 60% (with resultant
improvements to link and load times), better scope for the
optimizer to improve code and up to a 20% reduction in binary size.
Using these options correctly yields a binary with a similar symbol
count to a Windows DLL.
Perhaps more importantly, this new feature finally allows (with
careful planning) complete avoidance of symbol clashes when
manually loading shared objects with RTLD_GLOBAL, thus finally
solving problems many projects such as python were forced to use
RTLD_LOCAL for (with its resulting issues for C++ correctness). You
can find more information about using these options at
[13]https://gcc.gnu.org/wiki/Visibility.
__________________________________________________________________

[14]GCC 4.0.1

This is the [15]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.0.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

[16]GCC 4.0.2

This is the [17]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.0.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Unfortunately, due to a release engineering failure, this release has a
regression on Solaris that will affect some C++ programs. We suggest
that Solaris users apply a [18]patch that corrects the problem. Users
who do not wish to apply the patch should explicitly link C++ programs
with the -pthreads option, even if they do not use threads. This
problem has been corrected in the current 4.0 branch sources and will
not be present in GCC 4.0.3.

[19]GCC 4.0.3

Starting with this release, the function getcontext is recognized by
the compiler as having the same semantics as the setjmp function. In
particular, the compiler will ensure that all registers are dead before
calling such a function and will emit a warning about the variables
that may be clobbered after the second return from the function.

[20]GCC 4.0.4

This is the [21]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 4.0.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

The 4.0.4 release is provided for those that require a high degree of
binary compatibility with previous 4.0.x releases. For most users, the
GCC team recommends that version 4.1.1 or later be used instead."

For questions related to the use of GCC, please consult these web
pages and the [22]GCC manuals. If that fails, the
[23][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [24][email protected]. All of [25]our lists have public
archives.

Copyright (C) [26]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [27]maintained by the GCC team. Last modified
2025-01-31.

References

1. https://gcc.gnu.org/gcc-4.0/changes.html#4.0.4
2. https://www.cl.cam.ac.uk/~mgk25/ucs/quotes.html
3. https://gcc.gnu.org/projects/tree-ssa/
4. https://gcc.gnu.org/projects/tree-ssa/vectorization.html
5. https://gcc.gnu.org/news/sms.html
6. https://www.akkadia.org/drepper/dsohowto.pdf
7. https://gcc.gnu.org/gcc-4.0/changes.html#visibility
8. https://itanium-cxx-abi.github.io/cxx-abi/
9. https://gcc.gnu.org/fortran/
10. https://gcc.gnu.org/install/
11. https://gcc.gnu.org/gcc-4.0/changes.html#targets
12. https://gcc.gnu.org/gcc-4.0/changes.html#obsolete_systems
13. https://gcc.gnu.org/wiki/Visibility
14. https://gcc.gnu.org/gcc-4.0/changes.html#GCC4.0.1
15. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.0.1
16. https://gcc.gnu.org/gcc-4.0/changes.html#GCC4.0.2
17. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.0.2
18. https://gcc.gnu.org/ml/gcc-cvs/2005-09/msg00984.html
19. https://gcc.gnu.org/gcc-4.0/changes.html#GCC4.0.3
20. https://gcc.gnu.org/gcc-4.0/changes.html#GCC4.0.4
21. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.0.4
22. https://gcc.gnu.org/onlinedocs/
23. mailto:[email protected]
24. mailto:[email protected]
25. https://gcc.gnu.org/lists.html
26. https://www.fsf.org/
27. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-3.4/index.html

GCC 3.4 Release Series

(This release series is no longer supported.)

May 26, 2006

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 3.4.6.

This release is a bug-fix release, containing fixes for regressions in
GCC 3.4.4 relative to previous releases of GCC. This is the last of the
3.4.x series.

The GCC 3.4 release series includes numerous [2]new features,
improvements, bug fixes, and other changes, thanks to an [3]amazing
group of volunteers.

Release History

GCC 3.4.6
March 6, 2006 ([4]changes)

GCC 3.4.5
November 30, 2005 ([5]changes)

GCC 3.4.4
May 18, 2005 ([6]changes)

GCC 3.4.3
November 4, 2004 ([7]changes)

GCC 3.4.2
September 6, 2004 ([8]changes)

GCC 3.4.1
July 1, 2004 ([9]changes)

GCC 3.4.0
April 18, 2004 ([10]changes)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [11]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [12]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [13]GCC
project web site or contact the [14]GCC development mailing list.

To obtain GCC please use [15]our mirror sites, or [16]our version
control system.

For questions related to the use of GCC, please consult these web
pages and the [17]GCC manuals. If that fails, the
[18][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [19][email protected]. All of [20]our lists have public
archives.

Copyright (C) [21]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [22]maintained by the GCC team. Last modified
2022-10-26.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-3.4/changes.html
3. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
4. https://gcc.gnu.org/gcc-3.4/changes.html#3.4.6
5. https://gcc.gnu.org/gcc-3.4/changes.html#3.4.5
6. https://gcc.gnu.org/gcc-3.4/changes.html#3.4.4
7. https://gcc.gnu.org/gcc-3.4/changes.html#3.4.3
8. https://gcc.gnu.org/gcc-3.4/changes.html#3.4.2
9. https://gcc.gnu.org/gcc-3.4/changes.html#3.4.1
10. https://gcc.gnu.org/gcc-3.4/changes.html
11. https://gcc.gnu.org/gcc-3.4/buildstat.html
12. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
13. https://gcc.gnu.org/index.html
14. mailto:[email protected]
15. https://gcc.gnu.org/mirrors.html
16. https://gcc.gnu.org/git.html
17. https://gcc.gnu.org/onlinedocs/
18. mailto:[email protected]
19. mailto:[email protected]
20. https://gcc.gnu.org/lists.html
21. https://www.fsf.org/
22. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-3.4/changes.html

GCC 3.4 Release Series
Changes, New Features, and Fixes

The final release in the 3.4 release series is [1]GCC 3.4.6. The series
is now closed.

GCC 3.4 has [2]many improvements in the C++ front end. Before reporting
a bug, please make sure it's really GCC, and not your code, that is
broken.

Caveats

* GNU Make is now required to build GCC.
* With -nostdinc the preprocessor used to ignore both standard
include paths and include paths contained in environment variables.
It was neither documented nor intended that environment variable
paths be ignored, so this has been corrected.
* GCC no longer accepts the options -fvolatile, -fvolatile-global and
-fvolatile-static. It is unlikely that they worked correctly in any
3.x release.
* GCC no longer ships <varargs.h>. Use <stdarg.h> instead.
* Support for all the systems [3]obsoleted in GCC 3.3 has been
removed from GCC 3.4. See below for a [4]list of systems which are
obsoleted in this release.
* GCC now requires an ISO C90 (ANSI C89) C compiler to build. K&R C
compilers will not work.
* The implementation of the [5]MIPS ABIs has changed. As a result,
the code generated for certain MIPS targets will not be binary
compatible with earlier releases.
* In previous releases, the MIPS port had a fake "hilo" register with
the user-visible name accum. This register has been removed.
* The implementation of the [6]SPARC ABIs has changed. As a result,
the code generated will not be binary compatible with earlier
releases in certain cases.
* The configure option --enable-threads=pthreads has been removed;
use --enable-threads=posix instead, which should have the same
effect.
* Code size estimates used by inlining heuristics for C, Objective-C,
C++ and Java have been redesigned significantly. As a result the
parameters of -finline-insns, --param max-inline-insns-single and
--param max-inline-insns-auto need to be reconsidered.
* --param max-inline-slope and --param min-inline-insns have been
removed; they are not needed for the new bottom-up inlining
heuristics.
* The new unit-at-a-time compilation scheme has several compatibility
issues:
+ The order in which functions, variables, and top-level asm
statements are emitted may have changed. Code relying on some
particular ordering needs to be updated. The majority of such
top-level asm statements can be replaced by section
attributes.
+ Unreferenced static variables and functions are removed. This
may result in undefined references when an asm statement
refers to the variable/function directly. In that case either
the variable/function shall be listed in asm statement operand
or in the case of top-level asm statements the attribute used
shall be used to force function/variable to be always output
and considered as a possibly used by unknown code.
For variables the attribute is accepted only by GCC 3.4 and
newer, while for earlier versions it is sufficient to use
unused to silence warnings about the variables not being
referenced. To keep code portable across different GCC
versions, you can use appropriate preprocessor conditionals.
+ Static functions now can use non-standard passing conventions
that may break asm statements calling functions directly.
Again the attribute used shall be used to prevent this
behavior.
As a temporary workaround, -fno-unit-at-a-time can be used, but
this scheme may not be supported by future releases of GCC.
* GCC 3.4 automatically places zero-initialized variables in the .bss
section on some operating systems. Versions of GNU Emacs up to (and
including) 21.3 will not work correctly when using this
optimization; you can use -fno-zero-initialized-in-bss to disable
it.
* If GCC 3.4 is configured with --enable-threads=posix (the default
on most targets that support pthreads) then _REENTRANT will be
defined unconditionally by some libstdc++ headers. C++ code which
relies on that macro to detect whether multi-threaded code is being
compiled might change in meaning, possibly resulting in linker
errors for single-threaded programs. Affected users of [7]Boost
should compile single-threaded code with -DBOOST_DISABLE_THREADS.
See Bugzilla for [8]more information.

General Optimizer Improvements

* Usability of the profile feedback and coverage testing has been
improved.
+ Performance of profiled programs has been improved by faster
profile merging code.
+ Better use of the profile feedback for optimization (loop
unrolling and loop peeling).
+ File locking support allowing fork() calls and parallel runs
of profiled programs.
+ Coverage file format has been redesigned.
+ gcov coverage tool has been improved.
+ make profiledbootstrap available to build a faster compiler.
Experiments made on i386 hardware showed an 11% speedup on -O0
and a 7.5% speedup on -O2 compilation of a [9]large C++
testcase.
+ New value profiling pass enabled via -fprofile-values
+ New value profile transformations pass enabled via -fvpt aims
to optimize some code sequences by exploiting knowledge about
value ranges or other properties of the operands. At the
moment a conversion of expensive divisions into cheaper
operations has been implemented.
+ New -fprofile-generate and -fprofile-use command-line options
to simplify the use of profile feedback.
* A new unit-at-a-time compilation scheme for C, Objective-C, C++ and
Java which is enabled via -funit-at-a-time (and implied by -O2). In
this scheme a whole file is parsed first and optimized later. The
following basic inter-procedural optimizations are implemented:
+ Removal of unreachable functions and variables
+ Discovery of local functions (functions with static linkage
whose address is never taken)
+ On i386, these local functions use register parameter passing
conventions.
+ Reordering of functions in topological order of the call graph
to enable better propagation of optimizing hints (such as the
stack alignments needed by functions) in the back end.
+ Call graph based out-of-order inlining heuristics which allows
to limit overall compilation unit growth (--param
inline-unit-growth).
Overall, the unit-at-a-time scheme produces a 1.3% improvement for
the SPECint2000 benchmark on the i386 architecture (AMD Athlon
CPU).
* More realistic code size estimates used by inlining for C,
Objective-C, C++ and Java. The growth of large functions can now be
limited via --param large-function-insns and --param
large-function-growth.
* A new cfg-level loop optimizer pass replaces the old loop unrolling
pass and adds two other loop transformations -- loop peeling and
loop unswitching -- and also uses the profile feedback to limit
code growth. (The three optimizations are enabled by
-funroll-loops, -fpeel-loops and -funswitch-loops flags,
respectively).
The old loop unroller still can be enabled by -fold-unroll-loops
and may produce better code in some cases, especially when the
webizer optimization pass is not run.
* A new web construction pass enabled via -fweb (and implied by -O3)
improves the quality of register allocation, CSE, first scheduling
pass and some other optimization passes by avoiding re-use of
pseudo registers with non-overlapping live ranges. The pass almost
always improves code quality but does make debugging difficult and
thus is not enabled by default by -O2
The pass is especially effective as cleanup after code duplication
passes, such as the loop unroller or the tracer.
* Experimental implementations of superblock or trace scheduling in
the second scheduling pass can be enabled via
-fsched2-use-superblocks and -fsched2-use-traces, respectively.

New Languages and Language specific improvements

Ada

* The Ada front end has been updated to include numerous bug fixes
and enhancements. These include:
+ Improved project file support
+ Additional set of warnings about potential wrong code
+ Improved error messages
+ Improved code generation
+ Improved cross reference information
+ Improved inlining
+ Better run-time check elimination
+ Better error recovery
+ More efficient implementation of unbounded strings
+ Added features in GNAT.Sockets, GNAT.OS_Lib, GNAT.Debug_Pools,
...
+ New GNAT.xxxx packages (e.g. GNAT.Strings,
GNAT.Exception_Action)
+ New pragmas
+ New -gnatS switch replacing gnatpsta
+ Implementation of new Ada features (in particular limited
with, limited aggregates)

C/Objective-C/C++

* Precompiled headers are now supported. Precompiled headers can
dramatically speed up compilation of some projects. There are some
known defects in the current precompiled header implementation that
will result in compiler crashes in relatively rare situations.
Therefore, precompiled headers should be considered a "technology
preview" in this release. Read the manual for details about how to
use precompiled headers.
* File handling in the preprocessor has been rewritten. GCC no longer
gets confused by symlinks and hardlinks, and now has a correct
implementation of #import and #pragma once. These two directives
have therefore been un-deprecated.
* The undocumented extension that allowed C programs to have a label
at the end of a compound statement, which has been deprecated since
GCC 3.0, has been removed.
* The cast-as-lvalue extension has been removed for C++ and
deprecated for C and Objective-C. In particular, code like this:
int i;
(char) i = 5;

or this:
char *p;
((int *) p)++;

is no longer accepted for C++ and will not be accepted for C and
Objective-C in a future version.
* The conditional-expression-as-lvalue extension has been deprecated
for C and Objective-C. In particular, code like this:
int a, b, c;
(a ? b : c) = 2;

will not be accepted for C and Objective-C in a future version.
* The compound-expression-as-lvalue extension has been deprecated for
C and Objective-C. In particular, code like this:
int a, b;
(a, b) = 2;

will not be accepted for C and Objective-C in a future version. A
possible non-intrusive workaround is the following:
(*(a, &b)) = 2;

* Several [10]built-in functions such as __builtin_popcount for
counting bits, finding the highest and lowest bit in a word, and
parity have been added.
* The -fwritable-strings option has been deprecated and will be
removed.
* Many C math library functions are now recognized as built-ins and
optimized.
* The C, C++, and Objective-C compilers can now handle source files
written in any character encoding supported by the host C library.
The default input character set is taken from the current locale,
and may be overridden with the -finput-charset command line option.
In the future we will add support for inline encoding markers.

[11]C++

* G++ is now much closer to full conformance to the ISO/ANSI C++
standard. This means, among other things, that a lot of invalid
constructs which used to be accepted in previous versions will now
be rejected. It is very likely that existing C++ code will need to
be fixed. This document lists some of the most common issues.
* A hand-written recursive-descent C++ parser has replaced the
YACC-derived C++ parser from previous GCC releases. The new parser
contains much improved infrastructure needed for better parsing of
C++ source codes, handling of extensions, and clean separation
(where possible) between proper semantics analysis and parsing. The
new parser fixes many bugs that were found in the old parser.
* You must now use the typename and template keywords to disambiguate
dependent names, as required by the C++ standard.
struct K {
typedef int mytype_t;
};

template <class T1> struct A {
template <class T2> struct B {
void callme(void);
};

template <int N> void bar(void)
{
// Use 'typename' to tell the parser that T1::mytype_t names
// a type. This is needed because the name is dependent (in
// this case, on template parameter T1).
typename T1::mytype_t x;
x = 0;
}
};

template <class T> void template_func(void)
{
// Use 'template' to prefix member templates within
// dependent types (a has type A<T>, which depends on
// the template parameter T).
A<T> a;
a.template bar<0>();

// Use 'template' to tell the parser that B is a nested
// template class (dependent on template parameter T), and
// 'typename' because the whole A<T>::B<int> is
// the name of a type (again, dependent).
typename A<T>::template B<int> b;
b.callme();
}

void non_template_func(void)
{
// Outside of any template class or function, no names can be
// dependent, so the use of the keyword 'typename' and 'template'
// is not needed (and actually forbidden).
A<K> a;
a.bar<0>();
A<K>::B<float> b;
b.callme();
}
* In a template definition, unqualified names will no longer find
members of a dependent base (as specified by [temp.dep]/3 in the
C++ standard). For example,
template <typename T> struct B {
int m;
int n;
int f ();
int g ();
};
int n;
int g ();
template <typename T> struct C : B<T> {
void h ()
{
m = 0; // error
f (); // error
n = 0; // ::n is modified
g (); // ::g is called
}
};
You must make the names dependent, e.g. by prefixing them with
this->. Here is the corrected definition of C<T>::h,
template <typename T> void C<T>::h ()
{
this->m = 0;
this->f ();
this->n = 0
this->g ();
}
As an alternative solution (unfortunately not backwards compatible
with GCC 3.3), you may use using declarations instead of this->:
template <typename T> struct C : B<T> {
using B<T>::m;
using B<T>::f;
using B<T>::n;
using B<T>::g;
void h ()
{
m = 0;
f ();
n = 0;
g ();
}
};
* In templates, all non-dependent names are now looked up and bound
at definition time (while parsing the code), instead of later when
the template is instantiated. For instance:
void foo(int);

template <int> struct A {
static void bar(void){
foo('a');
}
};

void foo(char);

int main()
{
A<0>::bar(); // Calls foo(int), used to call foo(char).
}

* In an explicit instantiation of a class template, you must use
class or struct before the template-id:
template <int N>
class A {};

template A<0>; // error, not accepted anymore
template class A<0>; // OK
* The "named return value" and "implicit typename" extensions have
been removed.
* Default arguments in function types have been deprecated and will
be removed.
* ARM-style name-injection of friend declarations has been deprecated
and will be removed. For example: struct S { friend void f(); };
void g() { f(); } will not be accepted by future versions of G++;
instead a declaration of "f" will need to be present outside of the
scope of "S".
* Covariant returns are implemented for all but varadic functions
that require an adjustment.
* When -pedantic is used, G++ now issues errors about spurious
semicolons. For example,
namespace N {}; // Invalid semicolon.
void f() {}; // Invalid semicolon.
* G++ no longer accepts attributes for a declarator after the
initializer associated with that declarator. For example,
X x(1) __attribute__((...));
is no longer accepted. Instead, use:
X x __attribute__((...)) (1);
* Inside the scope of a template class, the name of the class itself
can be treated as either a class or a template. So GCC used to
accept the class name as argument of type template, and template
template parameter. However this is not C++ standard compliant. Now
the name is not treated as a valid template template argument
unless you qualify the name by its scope. For example, the code
below no longer compiles.
template <template <class> class TT> class X {};
template <class T> class Y {
X<Y> x; // Invalid, Y is always a type template parameter.
};
The valid code for the above example is
X< ::Y> x; // Valid.
(Notice the space between < and : to prevent GCC to interpret this
as a digraph for [.)
* Friend declarations that refer to template specializations are
rejected if the template has not already been declared. For
example,
template <typename T>
class C {
friend void f<> (C&);
};
is rejected. You must first declare f as a template,
template <typename T>
void f(T);
* In case of friend declarations, every name used in the friend
declaration must be accessible at the point of that declaration.
Previous versions of G++ used to be less strict about this and
allowed friend declarations for private class members, for example.
See the ISO C++ Standard Committee's [12]defect report #209 for
details.
* Declaration of member functions of class templates as friends are
supported. For example,
template <typename T> struct A {
void f();
};
class C {
template <typename T> friend void A<T>::f();
};
* You must use template <> to introduce template specializations, as
required by the standard. For example,
template <typename T>
struct S;

struct S<int> { };
is rejected. You must write,
template <> struct S<int> {};
* G++ used to accept code like this,
struct S {
int h();
void f(int i = g());
int g(int i = h());
};
This behavior is not mandated by the standard. Now G++ issues an
error about this code. To avoid the error, you must move the
declaration of g before the declaration of f. The default arguments
for g must be visible at the point where it is called.
* The C++ ABI Section 3.3.3 specifications for the array construction
routines __cxa_vec_new2 and __cxa_vec_new3 were changed to return
NULL when the allocator argument returns NULL. These changes are
incorporated into the libstdc++ runtime library.
* Using a name introduced by a typedef in a friend declaration or in
an explicit instantiation is now rejected, as specified by the ISO
C++ standard.
class A;
typedef A B;
class C {
friend class B; // error, no typedef name here
friend B; // error, friend always needs class/struct/enum
friend class A; // OK
};

template <int> class Q {};
typedef Q<0> R;
template class R; // error, no typedef name here
template class Q<0>; // OK
* When allocating an array with a new expression, GCC used to allow
parentheses around the type name. This is actually ill-formed and
it is now rejected:
int* a = new (int)[10]; // error, not accepted anymore
int* a = new int[10]; // OK
* When binding an rvalue of class type to a reference, the copy
constructor of the class must be accessible. For instance, consider
the following code:
class A
{
public:
A();

private:
A(const A&); // private copy ctor
};

A makeA(void);
void foo(const A&);

void bar(void)
{
foo(A()); // error, copy ctor is not accessible
foo(makeA()); // error, copy ctor is not accessible

A a1;
foo(a1); // OK, a1 is a lvalue
}
This might be surprising at first sight, especially since most
popular compilers do not correctly implement this rule ([13]further
details).
* When forming a pointer to member or a pointer to member function,
access checks for class visibility (public, protected, private) are
now performed using the qualifying scope of the name itself. This
is better explained with an example:
class A
{
public:
void pub_func();
protected:
void prot_func();
private:
void priv_func();
};

class B : public A
{
public:
void foo()
{
&A::pub_func; // OK, pub_func is accessible through A
&A::prot_func; // error, cannot access prot_func through A
&A::priv_func; // error, cannot access priv_func through A

&B::pub_func; // OK, pub_func is accessible through B
&B::prot_func; // OK, can access prot_func through B (within B)
&B::priv_func; // error, cannot access priv_func through B
}
};

Runtime Library (libstdc++)

* Optimization work:
+ Streamlined streambuf, filebuf, separate synched with C
Standard I/O streambuf.
+ All formatted I/O now uses cached locale information.
+ STL optimizations (memory/speed for list, red-black trees as
used by sets and maps).
+ More use of GCC builtins.
+ String optimizations (avoid contention on
increment/decrement-and-test of the reference count in the
empty-string object, constructor from input_iterators
speedup).
* Static linkage size reductions.
* Large File Support (files larger than 2 GB on 32-bit systems).
* Wide character and variable encoding filebuf work (UTF-8, Unicode).
* Generic character traits.
* Also support wchar_t specializations on Mac OS 10.3.x, FreeBSD 5.x,
Solaris 2.7 and above, AIX 5.x, Irix 6.5.
* The allocator class is now standard-conformant, and two additional
extension allocators have been added, mt_alloc and
bitmap_allocator.
* PCH support: -include bits/stdc++.h (2x compile speedup).
* Rewrote __cxa_demangle with support for C++ style allocators.
* New debug modes for STL containers and iterators.
* Testsuite rewrite: five times as many tests, plus increasingly
sophisticated tests, including I/O, MT, multi-locale, wide and
narrow characters.
* Use current versions of GNU "autotools" for build/configuration.

Objective-C

* The Objective-C front end has been updated to include the numerous
bug fixes and enhancements previously available only in Apple's
version of GCC. These include:
+ Structured exception (@try... @catch... @finally, @throw) and
synchronization (@synchronized) support. These are accessible
via the -fobjc-exceptions switch; as of this writing, they may
only be used in conjunction with -fnext-runtime on Mac OS X
10.3 and later. See [14]Options Controlling Objective-C
Dialect for more information.
+ An overhaul of @encode logic. The C99 _Bool and C++ bool type
may now be encoded as 'B'. In addition, the back-end/codegen
dependencies have been removed.
+ An overhaul of message dispatch construction, ensuring that
the various receiver types (and casts thereof) are handled
properly, and that correct diagnostics are issued.
+ Support for "Zero-Link" (-fzero-link) and "Fix-and-Continue"
(-freplace-objc-classes) debugging modes, currently available
on Mac OS X 10.3 and later. See [15]Options Controlling
Objective-C Dialect for more information.
+ Access to optimized runtime entry points (-fno-nil-receivers )
on the assumption that message receivers are never nil. This
is currently available on Mac OS X 10.3 and later. See
[16]Options Controlling Objective-C Dialect for more
information.

Java

* Compiling a .jar file will now cause non-.class entries to be
automatically compiled as resources.
* libgcj has been ported to Darwin.
* Jeff Sturm has adapted Jan Hubicka's call graph optimization code
to gcj.
* libgcj has a new gcjlib URL type; this lets URLClassLoader load
code from shared libraries.
* libgcj has been much more completely merged with [17]GNU Classpath.
* Class loading is now much more correct; in particular the caller's
class loader is now used when that is required.
* [18]Eclipse 2.x will run out of the box using gij.
* Parts of java.nio have been implemented. Direct and indirect
buffers work, as do fundamental file and socket operations.
* java.awt has been improved, though it is still not ready for
general use.
* The HTTP protocol handler now uses HTTP/1.1 and can handle the POST
method.
* The MinGW port has matured. Enhancements include socket timeout
support, thread interruption, improved Runtime.exec() handling and
support for accented characters in filenames.

Fortran

* Fortran improvements are listed in the [19]Fortran documentation.

New Targets and Target Specific Improvements

Alpha

* Several [20]built-in functions have been added such as
__builtin_alpha_zap to allow utilizing the more obscure
instructions of the CPU.
* Parameter passing of complex arguments has changed to match the
ABI. This change is incompatible with previous GCC versions, but
does fix compatibility with the Tru64 compiler and several corner
cases where GCC was incompatible with itself.

ARM

* Nicolas Pitre has contributed his hand-coded floating-point support
code for ARM. It is both significantly smaller and faster than the
existing C-based implementation, even when building applications
for Thumb. The arm-elf configuration has been converted to use the
new code.
* Support for the Intel's iWMMXt architecture, a second generation
XScale processor, has been added. Enabled at run time with the
-mcpu=iwmmxt command line switch.
* A new ARM target has been added: arm-wince-pe. This is similar to
the arm-pe target, but it defaults to using the APCS32 ABI.
* The existing ARM pipeline description has been converted to the use
the [21]DFA processor pipeline model. There is not much change in
code performance, but the description is now [22]easier to
understand.
* Support for the Cirrus EP9312 Maverick floating point co-processor
added. Enabled at run time with the -mcpu=ep9312 command line
switch. Note however that the multilibs to support this chip are
currently disabled in gcc/config/arm/t-arm-elf, so if you want to
enable their production you will have to uncomment the entries in
that file.

H8/300

* Support for long long has been added.
* Support for saveall attribute has been added.
* Pavel Pisa contributed hand-written 32-bit-by-32-bit division code
for H8/300H and H8S, which is much faster than the previous
implementation.
* A lot of small performance improvements.

IA-32/AMD64 (x86-64)

* Tuning for K8 (AMD Opteron/Athlon64) core is available via
-march=k8 and -mcpu=k8.
* Scalar SSE code generation carefully avoids reformatting penalties,
hidden dependencies and minimizes the number of uops generated on
both Intel and AMD CPUs.
* Vector MMX and SSE operands are now passed in registers to improve
performance and match the argument passing convention used by the
Intel C++ Compiler. As a result it is not possible to call
functions accepting vector arguments compiled by older GCC version.
* Conditional jump elimination is now more aggressive on modern CPUs.
* The Athlon ports has been converted to use the DFA processor
pipeline description.
* Optimization of indirect tail calls is now possible in a similar
fashion as direct sibcall optimization.
* Further small performance improvements.
* -m128bit-long-double is now less buggy.
* __float128 support in 64-bit compilation.
* Support for data structures exceeding 2GB in 64-bit mode.
* -mcpu has been renamed to -mtune.

IA-64

* Tuning code for the Itanium 2 processor has been added. The
generation of code tuned for Itanium 2 (option -mtune=itanium2) is
enabled by default now. To generate code tuned for Itanium 1 the
option -mtune=itanium1 should be used.
* [23]DFA processor pipeline descriptions for the IA-64 processors
have been added. This resulted in about 3% improvement on the
SPECInt2000 benchmark for Itanium 2.
* Instruction bundling for the IA-64 processors has been rewritten
using the DFA pipeline hazard recognizer. It resulted in about 60%
compiler speedup on the SPECInt2000 C programs.

M32R

* Support for the M32R/2 processor has been added by Renesas.
* Support for an M32R GNU/Linux target and PIC code generation has
been added by Renesas.

M68000

* Bernardo Innocenti (Develer S.r.l.) has contributed the
m68k-uclinux target, based on former work done by Paul Dale
(SnapGear Inc.). Code generation for the ColdFire processors family
has been enhanced and extended to support the MCF 53xx and MCF 54xx
cores, integrating former work done by Peter Barada (Motorola).

MIPS

Processor-specific changes

* Support for the RM7000 and RM9000 processors has been added. It can
be selected using the -march compiler option and should work with
any MIPS I (mips-*) or MIPS III (mips64-*) configuration.
* Support for revision 2 of the MIPS32 ISA has been added. It can be
selected with the command-line option -march=mips32r2.
* There is a new option, -mfix-sb1, to work around certain SB-1
errata.

Configuration

* It is possible to customize GCC using the following configure-time
options:
+ --with-arch, which specifies the default value of the -march
option.
+ --with-tune, which specifies the default value of the -mtune
option.
+ --with-abi, which specifies the default ABI.
+ --with-float=soft, which tells GCC to use software floating
point by default.
+ --with-float=hard, which tells GCC to use hardware floating
point by default.
* A 64-bit GNU/Linux port has been added. The associated
configurations are mips64-linux-gnu and mips64el-linux-gnu.
* The 32-bit GNU/Linux port now supports Java.
* The IRIX 6 configuration now supports the o32 ABI and will build
o32 multilibs by default. This support is compatible with both
binutils and the SGI tools, but note that several features,
including debugging information and DWARF2 exception handling, are
only available when using the GNU assembler. Use of the GNU
assembler and linker (version 2.15 or above) is strongly
recommended.
* The IRIX 6 configuration now supports 128-bit long doubles.
* There are two new RTEMS-specific configurations, mips-rtems and
mipsel-rtems.
* There are two new *-elf configurations, mipsisa32r2-elf and
mipsisa32r2el-elf.

General

* Several [24]ABI bugs have been fixed. Unfortunately, these changes
will break binary compatibility with earlier releases.
* GCC can now use explicit relocation operators when generating
-mabicalls code. This behavior is controlled by -mexplicit-relocs
and can have several performance benefits. For example:
+ It allows for more optimization of GOT accesses, including
better scheduling and redundancy elimination.
+ It allows sibling calls to be implemented as jumps.
+ n32 and n64 leaf functions can use a call-clobbered global
pointer instead of $28.
+ The code to set up $gp can be removed from functions that
don't need it.
* A new option, -mxgot, allows the GOT to be bigger than 64k. This
option is equivalent to the assembler's -xgot option and should be
used instead of -Wa,-xgot.
* Frame pointer elimination is now supported when generating 64-bit
MIPS16 code.
* Inline block moves have been optimized to take more account of
alignment information.
* Many internal changes have been made to the MIPS port, mostly aimed
at reducing the reliance on assembler macros.

PowerPC

* GCC 3.4 releases have a number of fixes for PowerPC and PowerPC64
[25]ABI incompatibilities regarding the way parameters are passed
during functions calls. These changes may result in incompatibility
between code compiled with GCC 3.3 and GCC 3.4.

PowerPC Darwin

* Support for shared/dylib gcc libraries has been added. It is
enabled by default on powerpc-apple-darwin7.0.0 and up.
* Libgcj is enabled by default. On systems older than
powerpc-apple-darwin7.0.0 you need to install dlcompat.
* 128-bit IBM extended precision format support added for long
double.

PowerPC64 GNU/Linux

* By default, PowerPC64 GNU/Linux now uses natural alignment of
structure elements. The old four byte alignment for double, with
special rules for a struct starting with a double, can be chosen
with -malign-power. This change may result in incompatibility
between code compiled with GCC 3.3 and GCC 3.4.
* -mabi=altivec is now the default rather than -mabi=no-altivec.
* 128-bit IBM extended precision format support added for long
double.

S/390 and zSeries

* New command-line options allow to specify the intended execution
environment for generated code:
+ -mesa/-mzarch allows to specify whether to generate code
running in ESA/390 mode or in z/Architecture mode (this is
applicable to 31-bit code only).
+ -march allows to specify a minimum processor architecture
level (g5, g6, z900, or z990).
+ -mtune allows to specify which processor to tune for.
* It is possible to customize GCC using the following configure-time
options:
+ --with-mode, which specifies whether to default to assuming
ESA/390 or z/Architecture mode.
+ --with-arch, which specifies the default value of the -march
option.
+ --with-tune, which specifies the default value of the -mtune
option.
* Support for the z990 processor has been added, and can be selected
using -march=z990 or -mtune=z990. This includes instruction
scheduling tuned for the superscalar instruction pipeline of the
z990 processor as well as support for all new instructions provided
by the long-displacement facility.
* Support to generate 31-bit code optimized for zSeries processors
(running in ESA/390 or in z/Architecture mode) has been added. This
can be selected using -march=z900 and -mzarch respectively.
* Instruction scheduling for the z900 and z990 processors now uses
the DFA pipeline hazard recognizer.
* GCC no longer generates code to maintain a stack backchain,
previously used to generate stack backtraces for debugging
purposes. As replacement that does not incur runtime overhead,
DWARF-2 call frame information is provided by GCC; this is
supported by GDB 6.1. The old behavior can be restored using the
-mbackchain option.
* The stack frame size of functions may now exceed 2 GB in 64-bit
code.
* A port for the 64-bit IBM TPF operating system has been added; the
configuration is s390x-ibm-tpf. This configuration is supported as
cross-compilation target only.
* Various changes to improve the generated code have been
implemented, including:
+ GCC now uses the MULTIPLY AND ADD and MULTIPLY AND SUBTRACT
instructions to significantly speed up many floating-point
applications.
+ GCC now uses the ADD LOGICAL WITH CARRY and SUBTRACT LOGICAL
WITH BORROW instructions to speed up long long arithmetic.
+ GCC now uses the SEARCH STRING instruction to implement
strlen().
+ In many cases, function call overhead for 31-bit code has been
reduced by placing the literal pool after the function code
instead of after the function prolog.
+ Register 14 is no longer reserved in 64-bit code.
+ Handling of global register variables has been improved.

SPARC

* The option -mflat is deprecated.
* Support for large (> 2GB) frames has been added to the 64-bit port.
* Several [26]ABI bugs have been fixed. Unfortunately, these changes
will break binary compatibility with earlier releases.
* The default debugging format has been switched from STABS to
DWARF-2 for 32-bit code on Solaris 7 and later. DWARF-2 is already
the default debugging format for 64-bit code on Solaris.

SuperH

* Support for the SH2E processor has been added. Enabled at run time
with the -m2e command line switch, or at configure time by
specifying sh2e as the machine part of the target triple.

V850

* Support for the Mitsubishi V850E1 processor has been added. This is
a variant of the V850E processor with some additional debugging
instructions.

Xtensa

* Several ABI bugs have been fixed. Unfortunately, these changes
break binary compatibility with earlier releases.
+ For big-endian processors, the padding of aggregate return
values larger than a word has changed. If the size of an
aggregate return value is not a multiple of 32 bits, previous
versions of GCC inserted padding in the most-significant bytes
of the first return value register. Aggregates larger than a
word are now padded in the least-significant bytes of the last
return value register used. Aggregates smaller than a word are
still padded in the most-significant bytes. The return value
padding has not changed for little-endian processors.
+ Function arguments with 16-byte alignment are now properly
aligned.
+ The implementation of the va_list type has changed. A va_list
value created by va_start from a previous release cannot be
used with va_arg from this release, or vice versa.
* More processor configuration options for Xtensa processors are
supported:
+ the ABS instruction is now optional;
+ the ADDX* and SUBX* instructions are now optional;
+ an experimental CONST16 instruction can be used to synthesize
constants instead of loading them from constant pools.
These and other Xtensa processor configuration options can no
longer be enabled or disabled by command-line options; the
processor configuration must be specified by the xtensa-config.h
header file when building GCC. Additionally, the
-mno-serialize-volatile option is no longer supported.

[27]Obsolete Systems

Support for a number of older systems has been declared obsolete in GCC
3.4. Unless there is activity to revive them, the next release of GCC
will have their sources permanently removed.

All configurations of the following processor architectures have been
declared obsolete:
* Mitsubishi D30V, d30v-*
* AT&T DSP1600 and DSP1610, dsp16xx-*
* Intel 80960, i960

Also, some individual systems have been obsoleted:
* ARM Family
+ Support for generating code for operation in APCS/26 mode
(-mapcs-26).
* IBM ESA/390
+ "Bigfoot" port, i370-*. (The other port, s390-*, is actively
maintained and supported.)
* Intel 386 family
+ MOSS, i?86-moss-msdos and i?86-*-moss*
+ NCR 3000 running System V r.4, i?86-ncr-sysv4*
+ FreeBSD with a.out object format, i?86-*-freebsd*aout* and
i?86-*-freebsd2*
+ GNU/Linux with a.out object format, i?86-linux*aout*
+ GNU/Linux with libc5, a.k.a. glibc1, i?86-linux*libc1*
+ Interix versions before Interix 3, i?86-*-interix
+ Mach microkernel, i?86-mach*
+ SCO UnixWare with UDK, i?86-*-udk*
+ Generic System V releases 1, 2, and 3, i?86-*-sysv[123]*
+ VSTa microkernel, i386-*-vsta
* Motorola M68000 family
+ HPUX, m68k-hp-hpux* and m68000-hp-hpux*
+ NetBSD with a.out object format (before NetBSD 1.4),
m68k-*-*-netbsd* except m68k-*-*-netbsdelf*
+ Generic System V r.4, m68k-*-sysv4*
* VAX
+ Generic VAX, vax-*-* (This is generic VAX only; we have not
obsoleted any VAX triples for specific operating systems.)

Documentation improvements

Other significant improvements

* The build system has undergone several significant cleanups.
Subdirectories will only be configured if they are being built, and
all subdirectory configures are run from the make command. The top
level has been autoconfiscated.
* Building GCC no longer writes to its source directory. This should
help those wishing to share a read-only source directory over NFS
or build from a CD. The exceptions to this feature are if you
configure with either --enable-maintainer-mode or
--enable-generated-files-in-srcdir.
* The -W warning option has been renamed to -Wextra, which is more
easily understood. The older spelling will be retained for
backwards compatibility.
* Substantial improvements in compile time have been made,
particularly for non-optimizing compilations.
__________________________________________________________________

[28]GCC 3.4.0

Bug Fixes

A vast number of bugs have been fixed in 3.4.0, too many to publish a
complete list here. [29]Follow this link to query the Bugzilla database
for the list of over 900 bugs fixed in 3.4.0. This is the list of all
bugs marked as resolved and fixed in 3.4.0 that are not flagged as 3.4
regressions.
__________________________________________________________________

[30]GCC 3.4.1

Bug Fixes

This section lists the problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 3.4.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Bootstrap failures

* [31]10129 Ada bootstrap fails on PPC-Darwin - invalid assembler
emitted - PIC related
* [32]14576 [ARM] ICE in libiberty when building gcc-3.4 for arm-elf
* [33]14760 A bug in configure.in prevents using both
--program-suffix and --program-prefix
* [34]14671 [hppa64] bootstrap fails: ICE in
save_call_clobbered_regs, in caller_save.c
* [35]15093 [alpha][Java] make bootstrap fails to configure libffi on
Alpha
* [36]15178 Solaris 9/x86 fails linking after stage 3

Multi-platform internal compiler errors (ICEs)

* [37]12753 (preprocessor) Memory corruption in preprocessor on bad
input
* [38]13985 ICE in gcc.c-torture/compile/930621-1.c
* [39]14810 (c++) tree check failures with invalid code involving
templates
* [40]14883 (c++) ICE on invalid code, in cp_parser_lookup_name, in
cp/parser.c
* [41]15044 (c++) ICE on syntax error, template header
* [42]15057 (c++) Compiling of conditional value throw constructs
cause a segmentation violation
* [43]15064 (c++) typeid of template parameter gives ICE
* [44]15142 (c++) ICE when passing a string where a char* is expected
in a throw statement
* [45]15159 ICE in rtl_verify_flow_info_1
* [46]15165 (c++) ICE in instantiate_template
* [47]15193 Unary minus using pointer to V4SF vector causes
-fforce-mem to exhaust all memory
* [48]15209 (c++) Runs out of memory with packed structs
* [49]15227 (c++) Trouble with invalid function definition
* [50]15285 (c++) instantiate_type ICE when forming pointer to
template function
* [51]15299 (c++) ICE in resolve_overloaded_unification
* [52]15329 (c++) ICE on constructor of member template
* [53]15550 ICE in extract_insn, in recog.c
* [54]15554 (c++) ICE in tsubst_copy, in cp/pt.c
* [55]15640 (c++) ICE on invalid code in arg_assoc, in
cp/name-lookup.c
* [56]15666 [unit-at-a-time] Gcc abort on valid code
* [57]15696 (c++) ICE with bad pointer-to-member code
* [58]15701 (c++) ICE with friends and template template parameter
* [59]15761 ICE in do_SUBST, in combine.c
* [60]15829 (c++) ICE on Botan-1.3.13 due to -funroll-loops

Ada

* [61]14538 All RTEMS targets broken for gnat

C front end

* [62]12391 missing warning about assigning to an incomplete type
* [63]14649 atan(1.0) should not be a constant expression
* [64]15004 [unit-at-a-time] no warning for unused paramater in
static function
* [65]15749 --pedantic-errors behaves differently from --pedantic
with C-compiler on GNU/Linux

C++ compiler and library

* [66]10646 non-const reference is incorrectly matched in a "const T"
partial specialization
* [67]12077 wcin.rdbuf()->in_avail() return value too high
* [68]13598 enc_filebuf doesn't work
* [69]14211 const_cast returns lvalue but should be rvalue
* [70]14220 num_put::do_put() undesired float/double behavior
* [71]14245 problem with user-defined allocators in std::basic_string
* [72]14340 libstdc++ Debug mode: failure to convert iterator to
const_iterator
* [73]14600 __gnu_cxx::stdio_sync_filebuf should expose internal
FILE*
* [74]14668 no warning anymore for reevaluation of declaration
* [75]14775 LFS (large file support) tests missing
* [76]14821 Duplicate namespace alias declaration should not conflict
* [77]14930 Friend declaration ignored
* [78]14932 cannot use offsetof to get offsets of array elements in
g++ 3.4.0
* [79]14950 [non unit-at-a-time] always_inline does not mix with
templates and -O0
* [80]14962 g++ ignores #pragma redefine_extname
* [81]14975 Segfault on low-level write error during imbue
* [82]15002 Linewise stream input is unusably slow (std::string slow)
* [83]15025 compiler accepts redeclaration of template as
non-template
* [84]15046 [arm] Math functions misdetected by cross configuration
* [85]15069 a bit test on a variable of enum type is miscompiled
* [86]15074 g++ -lsupc++ still links against libstdc++
* [87]15083 spurious "statement has no effect" warning
* [88]15096 parse error with templates and pointer to const member
* [89]15287 combination of operator[] and operator .* fails in
templates
* [90]15317 __attribute__ unused in first parameter of constructor
gives error
* [91]15337 sizeof on incomplete type diagnostic
* [92]15361 bitset<>::_Find_next fails
* [93]15412 _GLIBCXX_ symbols symbols defined and used in different
namespaces
* [94]15427 valid code results in incomplete type error
* [95]15471 Incorrect member pointer offsets in anonymous
structs/unions
* [96]15503 nested template problem
* [97]15507 compiler hangs while laying out union
* [98]15542 operator & and template definitions
* [99]15565 SLES9: leading + sign for unsigned int with showpos
* [100]15625 friend defined inside a template fails to find static
function
* [101]15629 Function templates, overloads, and friend name injection
* [102]15742 'noreturn' attribute ignored in method of template
functions.
* [103]15775 Allocator::pointer consistently ignored
* [104]15821 Duplicate namespace alias within namespace rejected
* [105]15862 'enum yn' fails (confict with undeclared builtin)
* [106]15875 rejects pointer to member in template
* [107]15877 valid code using templates and anonymous enums is
rejected
* [108]15947 Puzzling error message for wrong destructor declaration
in template class
* [109]16020 cannot copy __gnu_debug::bitset
* [110]16154 input iterator concept too restrictive
* [111]16174 deducing top-level consts

Java

* [112]14315 Java compiler is not parallel make safe

Fortran

* [113]15151 [g77] incorrect logical i/o in 64-bit mode

Objective-C

* [114]7993 private variables cannot be shadowed in subclasses

Optimization bugs

* [115]15228 useless copies of floating point operands
* [116]15345 [non-unit-at-a-time] unreferenced nested inline
functions not optimized away
* [117]15945 Incorrect floating point optimization
* [118]15526 ftrapv aborts on 0 * (-1)
* [119]14690 Miscompiled POOMA tests
* [120]15112 GCC generates code to write to unchanging memory

Preprocessor

* [121]15067 Minor glitch in the source of cpp

Main driver program bugs

* [122]1963 collect2 interprets -oldstyle_liblookup as -o
ldstyle_liblookup

x86-specific (Intel/AMD)

* [123]15717 Error: can't resolve `L0' {*ABS* section} - `xx' {*UND*
section}

HPPA-specific

* [124]14782 GCC produces an unaligned data access at -O2
* [125]14828 FAIL: gcc.c-torture/execute/20030408-1.c execution, -O2
* [126]15202 ICE in reload_cse_simplify_operands, in postreload.c

IA64-specific

* [127]14610 __float80 constants incorrectly emitted
* [128]14813 init_array sections are initialized in the wrong order
* [129]14857 GCC segfault on duplicated asm statement
* [130]15598 Gcc 3.4 ICE on valid code
* [131]15653 Gcc 3.4 ICE on valid code

MIPS-specific

* [132]15189 wrong filling of delay slot with -march=mips1 -G0
-mno-split-addresses -mno-explicit-relocs
* [133]15331 Assembler error building gnatlib on IRIX 6.5 with GNU as
2.14.91
* [134]16144 Bogus reference to __divdf3 when -O1
* [135]16176 Miscompilation of unaligned data in MIPS backend

PowerPC-specific

* [136]11591 ICE in gcc.dg/altivec-5.c
* [137]12028 powerpc-eabispe produces bad sCOND operation
* [138]14478 rs6000 geu/ltu patterns generate incorrect code
* [139]14567 long double and va_arg complex args
* [140]14715 Altivec stack layout may overlap gpr save with stack
temps
* [141]14902 (libstdc++) Stream checking functions fail when -pthread
option is used.
* [142]14924 Compiler ICE on valid code
* [143]14960 -maltivec affects vector return with -mabi=no-altivec
* [144]15106 vector varargs failure passing from altivec to
non-altivec code for -m32
* [145]16026 ICE in function.c:4804, assign_parms, when -mpowerpc64 &
half-word operation
* [146]15191 -maltivec -mabi=no-altivec results in mis-aligned lvx
and stvx
* [147]15662 Segmentation fault when an exception is thrown - even if
try and catch are specified

s390-specific

* [148]15054 Bad code due to overlapping stack temporaries

SPARC-specific

* [149]15783 ICE with union assignment in 64-bit mode
* [150]15626 GCC 3.4 emits "ld: warning: relocation error:
R_SPARC_UA32"

x86-64-specific

* [151]14326 boehm-gc hardcodes to 3DNow! prefetch for x86_64
* [152]14723 Backported -march=nocona from mainline
* [153]15290 __float128 failed to pass to function properly

Cygwin/Mingw32-specific

* [154]15250 Option -mms-bitfields support on GCC 3.4 is not
conformant to MS layout
* [155]15551 -mtune=pentium4 -O2 with sjlj EH breaks stack probe
worker on windows32 targets

Bugs specific to embedded processors

* [156]8309 [m68k] -m5200 produces erroneous SImode set of short
varaible on stack
* [157]13250 [SH] Gcc code for rotation clobbers the register, but
gcc continues to use the register as if it was not clobbered
* [158]13803 [coldfire] movqi operand constraints too restrictivefor
TARGET_COLDFIRE
* [159]14093 [SH] ICE for code when using -mhitachi option in SH
* [160]14457 [m6811hc] ICE with simple c++ source
* [161]14542 [m6811hc] ICE on simple source
* [162]15100 [SH] cc1plus got hang-up on
libstdc++-v3/testsuite/abi_check.cc
* [163]15296 [CRIS] Delayed branch scheduling causing invalid code on
cris-*
* [164]15396 [SH] ICE with -O2 -fPIC
* [165]15782 [coldfire] m68k_output_mi_thunk emits wrong code for
ColdFire

Testsuite problems (compiler not affected)

* [166]11610 libstdc++ testcases 27_io/* don't work properly remotely
* [167]15488 (libstdc++) possibly insufficient file permissions for
executing test suite
* [168]15489 (libstdc++) testsuite_files determined incorrectly

Documentation bugs

* [169]13928 (libstdc++) no whatis info in some man pages generated
by doxygen
* [170]14150 Ada documentation out of date
* [171]14949 (c++) Need to document method visibility changes
* [172]15123 libstdc++-doc: Allocators.3 manpage is empty
__________________________________________________________________

[173]GCC 3.4.2

Bug Fixes

This section lists the problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 3.4.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Bootstrap failures and issues

* [174]16469 [mips-sgi-irix5.3] bootstrap fails in
libstdc++-v3/testsuite
* [175]16344 [hppa-linux-gnu] libstdc++'s PCH built by
profiledbootstrap does not work with the built compiler
* [176]16842 [Solaris/x86] mkheaders can not find mkheaders.conf

Multi-platform internal compiler errors (ICEs)

* [177]12608 (c++) ICE: expected class 't', have 'x' (error_mark) in
cp_parser_class_specifier, in cp/parser.c
* [178]14492 ICE in loc_descriptor_from_tree, in dwarf2out.c
* [179]15461 (c++) ICE due to NRV and inlining
* [180]15890 (c++) ICE in c_expand_expr, in c-common.c
* [181]16180 ICE: segmentation fault in RTL optimization
* [182]16224 (c++) ICE in write_unscoped_name (template/namespace)
* [183]16408 ICE: in delete_insn, in cfgrtl.c
* [184]16529 (c++) ICE for: namespace-alias shall not be declared as
the name of any other entity
* [185]16698 (c++) ICE with exceptions and declaration of __cxa_throw
* [186]16706 (c++) ICE in finish_member_declaration, in
cp/semantics.c
* [187]16810 (c++) Legal C++ program with cast gives ICE in
build_ptrmemfunc
* [188]16851 (c++) ICE when throwing a comma expression
* [189]16870 (c++) Boost.Spirit causes ICE in tsubst, in cp/pt.c
* [190]16904 (c++) ICE in finish_class_member_access_expr, in
cp/typeck.c
* [191]16905 (c++) ICE (segfault) with exceptions
* [192]16964 (c++) ICE in cp_parser_class_specifier due to
redefinition
* [193]17068 (c++) ICE: tree check: expected class 'd', have 'x'
(identifier_node) in dependent_template_p, in cp/pt.c

Preprocessor bugs

* [194]16366 Preprocessor option -remap causes memory corruption

Optimization

* [195]15345 unreferenced nested inline functions not optimized away
* [196]16590 Incorrect execution when compiling with -O2
* [197]16693 Bitwise AND is lost when used within a cast to an enum
of the same precision
* [198]17078 Jump into if(0) substatement fails

Problems in generated debug information

* [199]13956 incorrect stabs for nested local variables

C front end bugs

* [200]16684 GCC should not warn about redundant redeclarations of
built-ins

C++ compiler and library

* [201]12658 Thread safety problems in locale::global() and
locale::locale()
* [202]13092 g++ accepts invalid pointer-to-member conversion
* [203]15320 Excessive memory consumption
* [204]16246 Incorrect template argument deduction
* [205]16273 Memory exhausted when using nested classes and virtual
functions
* [206]16401 ostringstream in gcc 3.4.x very slow for big data
* [207]16411 undefined reference to
__gnu_cxx::stdio_sync_filebuf<char, std::char_traits<char>
>::file()
* [208]16489 G++ incorrectly rejects use of a null constant integral
expression as a null constant pointer
* [209]16618 offsetof fails with constant member
* [210]16637 syntax error reported for valid input code
* [211]16717 __attribute__((constructor)) broken in C++
* [212]16813 compiler error in DEBUG version of range insertion
std::map::insert
* [213]16853 pointer-to-member initialization from incompatible one
accepted
* [214]16889 ambiguity is not detected
* [215]16959 Segmentation fault in ios_base::sync_with_stdio

Java compiler and library

* [216]7587 direct threaded interpreter not thread-safe
* [217]16473 ServerSocket accept() leaks file descriptors
* [218]16478 Hash synchronization deadlock with finalizers

Alpha-specific

* [219]10695 ICE in dwarf2out_frame_debug_expr, in dwarf2out.c
* [220]16974 could not split insn (ice in final_scan_insn, in
final.c)

x86-specific

* [221]16298 ICE in output_operand
* [222]17113 ICE with SSE2 intrinsics

x86-64 specific

* [223]14697 libstdc++ couldn't find 32bit libgcc_s

MIPS-specific

* [224]15869 [mips64] No NOP after LW (with -mips1 -O0)
* [225]16325 [mips64] value profiling clobbers gp on mips
* [226]16357 [mipsisa64-elf] ICE copying 7 bytes between extern
char[]s
* [227]16380 [mips64] Use of uninitialised register after dbra
conversion
* [228]16407 [mips64] Unaligned access to local variables
* [229]16643 [mips64] verify_local_live_at_start ICE after
crossjumping & cfgcleanup

ARM-specific

* [230]15927 THUMB -O2: strength-reduced iteration variable ends up
off by 1
* [231]15948 THUMB: ICE with non-commutative cbranch
* [232]17019 THUMB: bad switch statement in md code for
addsi3_cbranch_scratch

IA64-specific

* [233]16130 ICE on valid code: in bundling, in config/ia64/ia64.c
(-mtune=merced)
* [234]16142 ICE on valid code: in bundling, in config/ia64/ia64.c
(-mtune=itanium)
* [235]16278 Gcc failed to build Linux kernel with -mtune=merced
* [236]16414 ICE on valid code: typo in comparison of asm_noperands
result
* [237]16445 ICE on valid code: don't count ignored insns
* [238]16490 ICE (segfault) while compiling with -fprofile-use
* [239]16683 ia64 does not honor SUBTARGET_EXTRA_SPECS

PowerPC-specific

* [240]16195 (ppc64): Miscompilation of GCC 3.3.x by 3.4.x
* [241]16239 ICE on ppc64 (mozilla 1.7 compile, -O1 -fno-exceptions
issue)

SPARC-specific

* [242]16199 ICE while compiling apache 2.0.49
* [243]16416 -m64 doesn't imply -mcpu=v9 anymore
* [244]16430 ICE when returning non-C aggregates larger than 16 bytes

Bugs specific to embedded processors

* [245]16379 [m32r] can't output large model function call of memcpy
* [246]17093 [m32r] ICE with -msdata=use -O0
* [247]17119 [m32r] ICE at switch case 0x8000

DJGPP-specific

* [248]15928 libstdc++ in 3.4.x doesn't cross-compile for djgpp

Alpha Tru64-specific

* [249]16210 libstdc++ gratuitously omits "long long" I/O

Testsuite, documentation issues (compiler is not affected):

* [250]15488 (libstdc++) possibly insufficient file permissions for
executing test suite
* [251]16250 ada/doctools runs makeinfo even in release tarball
__________________________________________________________________

[252]GCC 3.4.3

This is the [253]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 3.4.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Bootstrap failures

* [254]17369 [ia64] Bootstrap failure with binutils-2.15.90.0.1.1
* [255]17850 [arm-elf] bootstrap failure - libstdc++ uses strtold
when undeclared

Internal compiler errors (ICEs) affecting multiple platforms

* [256]13948 (java) GCJ segmentation fault while compiling GL4Java
.class files
* [257]14492 ICE in loc_descriptor_from_tree, in dwarf2out.c
* [258]16301 (c++) ICE when "strong" attribute is attached to a using
directive
* [259]16566 ICE with flexible arrays
* [260]17023 ICE with nested functions in parameter declaration
* [261]17027 ICE with noreturn function in loop at -O2
* [262]17524 ICE in grokdeclarator, in cp/decl.c
* [263]17826 (c++) ICE in cp_tree_equal

C and optimization bugs

* [264]15526 -ftrapv aborts on 0 * (-1)
* [265]16999 #ident stopped working
* [266]17503 quadratic behaviour in invalid_mode_change_p
* [267]17581 Long long arithmetic fails inside a switch/case
statement when compiled with -O2
* [268]18129 -fwritable-strings doesn't work

C++ compiler and library bugs

* [269]10975 incorrect initial ostringstream::tellp()
* [270]11722 Unbuffered filebuf::sgetn is slow
* [271]14534 Unrecognizing static function as a template parameter
when its return value is also templated
* [272]15172 Copy constructor optimization in aggregate
initialization
* [273]15786 Bad error message for frequently occuring error.
* [274]16162 Rejects valid member-template-definition
* [275]16612 empty basic_strings can't live in shared memory
* [276]16715 std::basic_iostream is instantiated when used, even
though instantiations are already contained in libstdc++
* [277]16848 code in /ext/demangle.h appears broken
* [278]17132 GCC fails to eliminate function template specialization
when argument deduction fails
* [279]17259 One more _S_leaf incorrectly qualified with _RopeRep::
in ropeimpl.h
* [280]17327 use of `enumeral_type' in template type unification
* [281]17393 "unused variable '._0'" warning with -Wall
* [282]17501 Confusion with member templates
* [283]17537 g++ not passing -lstdc++ to linker when all command line
arguments are libraries
* [284]17585 usage of unqualified name of static member from within
class not allowed
* [285]17821 Poor diagnostic for using "." instead of "->"
* [286]17829 wrong error: call of overloaded function is ambiguous
* [287]17851 Misleading diagnostic for invalid function declarations
with undeclared types
* [288]17976 Destructor is called twice
* [289]18020 rejects valid definition of enum value in template
* [290]18093 bogus conflict in namespace aliasing
* [291]18140 C++ parser bug when using >> in templates

Fortran

* [292]17541 data statements with double precision constants fail

x86-specific

* [293]17853 -O2 ICE for MMX testcase

SPARC-specific

* [294]17245 ICE compiling gsl-1.5 statistics/lag1.c

Darwin-specific

* [295]17167 FATAL:Symbol L_foo$stub already defined.

AIX-specific

* [296]17277 could not catch an exception when specified -maix64

Solaris-specific

* [297]17505 <cmath> calls acosf(), ceilf(), and other functions
missing from system libraries

HP/UX specific:

* [298]17684 /usr/ccs/bin/ld: Can't create libgcc_s.sl

ARM-specific

* [299]17384 ICE with mode attribute on structures

MIPS-specific

* [300]17770 No NOP after LWL with -mips1

Other embedded target specific

* [301]11476 [arc-elf] gcc ICE on newlib's vfprintf.c
* [302]14064 [avr-elf] -fdata-sections triggers ICE
* [303]14678 [m68hc11-elf] gcc ICE
* [304]15583 [powerpc-rtems] powerpc-rtems lacks __USE_INIT_FINI__
* [305]15790 [i686-coff] Alignment error building gcc with i686-coff
target
* [306]15886 [SH] Miscompilation with -O2 -fPIC
* [307]16884 [avr-elf] [fweb related] bug while initializing
variables

Bugs relating to debugger support

* [308]13841 missing debug info for _Complex function arguments
* [309]15860 [big-endian targets] No DW_AT_location debug info is
emitted for formal arguments to a function that uses "register"
qualifiers

Testsuite issues (compiler not affected)

* [310]17465 Testsuite in libffi overrides LD_LIBRARY_PATH
* [311]17469 Testsuite in libstdc++ overrides LD_LIBRARY_PATH
* [312]18138 [mips-sgi-irix6.5] libgcc_s.so.1 not found by 64-bit
testsuite

Documentation

* [313]15498 typo in gcc manual: non-existing locale example en_UK,
should be en_GB
* [314]15747 [mips-sgi-irix5.3] /bin/sh hangs during bootstrap:
document broken shell
* [315]16406 USE_LD_AS_NEEDED undocumented
__________________________________________________________________

[316]GCC 3.4.4

This is the [317]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 3.4.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).
__________________________________________________________________

[318]GCC 3.4.5

This is the [319]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 3.4.5 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Bootstrap issues

* [320]24688 sco_math fixincl breaks math.h

C compiler bugs

* [321]17188 struct Foo { } redefinition
* [322]20187 wrong code for ((unsigned char)(unsigned long
long)((a?a:1)&(a*b)))?0:1)
* [323]21873 infinite warning loop on bad array initializer
* [324]21899 enum definition accepts values to be overriden
* [325]22061 ICE in find_function_data, in function.c
* [326]22308 Failure to diagnose violation of constraint 6.516p2
* [327]22458 ICE on missing brace
* [328]22589 ICE casting to long long
* [329]24101 Segfault with preprocessed source

C++ compiler and library bugs

* [330]10611 operations on vector mode not recognized in C++
* [331]13377 unexpected behavior of namespace usage directive
* [332]16002 Strange error message with new parser
* [333]17413 local classes as template argument
* [334]17609 spurious error message after using keyword
* [335]17618 ICE in cp_convert_to_pointer, in cp/cvt.c
* [336]18124 ICE with invalid template template parameter
* [337]18155 typedef in template declaration not rejected
* [338]18177 ICE with const_cast for undeclared variable
* [339]18368 C++ error message regression
* [340]16378 ICE when returning a copy of a packed member
* [341]18466 int ::i; accepted
* [342]18512 ICE on invalid usage of template base class
* [343]18454 ICE when returning undefined type
* [344]18738 typename not allowed with non-dependent qualified name
* [345]18803 rejects access to operator() in template
* [346]19004 ICE in uses_template_parms, in cp/pt.c
* [347]19208 Spurious error about variably modified type
* [348]18253 bad error message / ICE for invalid template parameter
* [349]19608 ICE after friend function definition in local class
* [350]19884 ICE on explicit instantiation of a non-template
constructor
* [351]20153 ICE when C++ template function contains anonymous union
* [352]20563 Infinite loop in diagnostic (and ice after error
message)
* [353]20789 ICE with incomplete type in template
* [354]21336 Internal compiler error when using custom new operators
* [355]21768 ICE in error message due to violation of coding
conventions
* [356]21853 constness of pointer to data member ignored
* [357]21903 Default argument of template function causes a
compile-time error
* [358]21983 multiple diagnostics
* [359]21987 New testsuite failure
g++.dg/warn/conversion-function-1.C
* [360]22153 ICE on invalid template specialization
* [361]22172 Internal compiler error, seg fault.
* [362]21286 filebuf::xsgetn vs pipes
* [363]22233 ICE with wrong number of template parameters
* [364]22508 ICE after invalid operator new
* [365]22545 ICE with pointer to class member & user defined
conversion operator
* [366]23528 Wrong default allocator in ext/hash_map
* [367]23550 char_traits requirements/1.cc test bad math
* [368]23586 Bad diagnostic for invalid namespace-name
* [369]23624 ICE in invert_truthvalue, in fold-const.c
* [370]23639 Bad error message: not a member of '<declaration error>'
* [371]23797 ICE on typename outside template
* [372]23965 Bogus error message: no matching function for call to
'foo(<type error>)'
* [373]24052 &#`label_decl' not supported by dump_expr#<expression
error>
* [374]24580 virtual base class cause exception not to be caught

Problems in generated debug information

* [375]24267 Bad DWARF for altivec vectors

Optimizations issues

* [376]17810 ICE in verify_local_live_at_start
* [377]17860 Wrong generated code for loop with varying bound
* [378]21709 ICE on compile-time complex NaN
* [379]21964 broken tail call at -O2 or more
* [380]22167 Strange optimization bug when using -Os
* [381]22619 Compilation failure for real_const_1.f and
real_const_2.f90
* [382]23241 Invalid code generated for comparison of uchar to 255
* [383]23478 Miscompilation due to reloading of a var that is also
used in EH pad
* [384]24470 segmentation fault in cc1plus when compiling with -O
* [385]24950 ICE in operand_subword_force

Precompiled headers problems

* [386]14400 Cannot compile qt-x11-free-3.3.0
* [387]14940 PCH largefile test fails on various platforms

Preprocessor bugs

* [388]20239 ICE on empty preprocessed input
* [389]15220 "gcc -E -MM -MG" reports missing system headers in
source directory

Testsuite issues

* [390]19275 gcc.dg/20020919-1.c fails with -fpic/-fPIC on
i686-pc-linux-gnu

Alpha specific

* [391]21888 bootstrap failure with linker relaxation enabled

ARM specific

* [392]15342 [arm-linux]: ICE in verify_local_live_at_start
* [393]23985 Memory aliasing information incorrect in inlined memcpy

ColdFile specific

* [394]16719 Illegal move of byte into address register causes
compiler to ICE

HPPA specific

* [395]21723 ICE while building libgfortran
* [396]21841 -mhp-ld/-mgnu-ld documentation

IA-64 specific

* [397]23644 IA-64 hardware models and configuration options
documentation error
* [398]24718 Shared libgcc not used for linking by default

M68000 specific

* [399]18421 ICE in reload_cse_simplify_operands, in postreload.c

MIPS specific

* [400]20621 ICE in change_address_1, in emit-rtl.c

PowerPC and PowerPC64 specific

* [401]18583 error on valid code: const
__attribute__((altivec(vector__))) doesn't work in arrays
* [402]20191 ICE in reload_cse_simplify_operands
* [403]22083 AIX: TARGET_C99_FUNCTIONS is wrongly defined
* [404]23070 CALL_V4_CLEAR_FP_ARGS flag not properly set
* [405]23404 gij trashes args of functions with more than 8 fp args
* [406]23539 C & C++ compiler generating misaligned references
regardless of compiler flags
* [407]24102 floatdisf2_internal2 broken
* [408]24465 -mminimal-toc miscompilation of __thread vars

Solaris specific

* [409]19933 Problem with define of HUGE_VAL in math_c99
* [410]21889 Native Solaris assembler cannot grok DTP-relative debug
symbols

SPARC specific

* [411]19300 PCH failures on sparc-linux
* [412]20301 Assembler labels have a leading "-"
* [413]20673 C PCH testsuite assembly comparison failure

x86 and x86_64 specific

* [414]18582 ICE with arrays of type V2DF
* [415]19340 Compilation SEGFAULTs with -O1 -fschedule-insns2
-fsched2-use-traces
* [416]21716 ICE in reg-stack.c's swap_rtx_condition
* [417]24315 amd64 fails -fpeephole2
__________________________________________________________________

[418]GCC 3.4.6

This is the [419]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 3.4.6 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

For questions related to the use of GCC, please consult these web
pages and the [420]GCC manuals. If that fails, the
[421][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [422][email protected]. All of [423]our lists have public
archives.

Copyright (C) [424]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [425]maintained by the GCC team. Last modified
2025-01-31.

References

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147. https://gcc.gnu.org/PR15662
148. https://gcc.gnu.org/PR15054
149. https://gcc.gnu.org/PR15783
150. https://gcc.gnu.org/PR15626
151. https://gcc.gnu.org/PR14326
152. https://gcc.gnu.org/PR14723
153. https://gcc.gnu.org/PR15290
154. https://gcc.gnu.org/PR15250
155. https://gcc.gnu.org/PR15551
156. https://gcc.gnu.org/PR8309
157. https://gcc.gnu.org/PR13250
158. https://gcc.gnu.org/PR13803
159. https://gcc.gnu.org/PR14093
160. https://gcc.gnu.org/PR14457
161. https://gcc.gnu.org/PR14542
162. https://gcc.gnu.org/PR15100
163. https://gcc.gnu.org/PR15296
164. https://gcc.gnu.org/PR15396
165. https://gcc.gnu.org/PR15782
166. https://gcc.gnu.org/PR11610
167. https://gcc.gnu.org/PR15488
168. https://gcc.gnu.org/PR15489
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170. https://gcc.gnu.org/PR14150
171. https://gcc.gnu.org/PR14949
172. https://gcc.gnu.org/PR15123
173. https://gcc.gnu.org/gcc-3.4/changes.html#GCC3.4.2
174. https://gcc.gnu.org/PR16469
175. https://gcc.gnu.org/PR16344
176. https://gcc.gnu.org/PR16842
177. https://gcc.gnu.org/PR12608
178. https://gcc.gnu.org/PR14492
179. https://gcc.gnu.org/PR15461
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181. https://gcc.gnu.org/PR16180
182. https://gcc.gnu.org/PR16224
183. https://gcc.gnu.org/PR16408
184. https://gcc.gnu.org/PR16529
185. https://gcc.gnu.org/PR16698
186. https://gcc.gnu.org/PR16706
187. https://gcc.gnu.org/PR16810
188. https://gcc.gnu.org/PR16851
189. https://gcc.gnu.org/PR16870
190. https://gcc.gnu.org/PR16904
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192. https://gcc.gnu.org/PR16964
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198. https://gcc.gnu.org/PR17078
199. https://gcc.gnu.org/PR13956
200. https://gcc.gnu.org/PR16684
201. https://gcc.gnu.org/PR12658
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225. https://gcc.gnu.org/PR16325
226. https://gcc.gnu.org/PR16357
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230. https://gcc.gnu.org/PR15927
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254. https://gcc.gnu.org/PR17369
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298. https://gcc.gnu.org/PR17684
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302. https://gcc.gnu.org/PR14064
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315. https://gcc.gnu.org/PR16406
316. https://gcc.gnu.org/gcc-3.4/changes.html#GCC3.4.4
317. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=3.4.4
318. https://gcc.gnu.org/gcc-3.4/changes.html#GCC3.4.5
319. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=3.4.5
320. https://gcc.gnu.org/PR24688
321. https://gcc.gnu.org/PR17188
322. https://gcc.gnu.org/PR20187
323. https://gcc.gnu.org/PR21873
324. https://gcc.gnu.org/PR21899
325. https://gcc.gnu.org/PR22061
326. https://gcc.gnu.org/PR22208
327. https://gcc.gnu.org/PR22458
328. https://gcc.gnu.org/PR22589
329. https://gcc.gnu.org/PR24101
330. https://gcc.gnu.org/PR10611
331. https://gcc.gnu.org/PR13377
332. https://gcc.gnu.org/PR16002
333. https://gcc.gnu.org/PR17413
334. https://gcc.gnu.org/PR17609
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336. https://gcc.gnu.org/PR18124
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339. https://gcc.gnu.org/PR18368
340. https://gcc.gnu.org/PR18378
341. https://gcc.gnu.org/PR18466
342. https://gcc.gnu.org/PR18512
343. https://gcc.gnu.org/PR18545
344. https://gcc.gnu.org/PR18738
345. https://gcc.gnu.org/PR18803
346. https://gcc.gnu.org/PR19004
347. https://gcc.gnu.org/PR19208
348. https://gcc.gnu.org/PR19253
349. https://gcc.gnu.org/PR19608
350. https://gcc.gnu.org/PR19884
351. https://gcc.gnu.org/PR20153
352. https://gcc.gnu.org/PR20563
353. https://gcc.gnu.org/PR20789
354. https://gcc.gnu.org/PR21336
355. https://gcc.gnu.org/PR21768
356. https://gcc.gnu.org/PR21853
357. https://gcc.gnu.org/PR21903
358. https://gcc.gnu.org/PR21983
359. https://gcc.gnu.org/PR21987
360. https://gcc.gnu.org/PR22153
361. https://gcc.gnu.org/PR22172
362. https://gcc.gnu.org/PR21286
363. https://gcc.gnu.org/PR22233
364. https://gcc.gnu.org/PR22508
365. https://gcc.gnu.org/PR22545
366. https://gcc.gnu.org/PR23528
367. https://gcc.gnu.org/PR23550
368. https://gcc.gnu.org/PR23586
369. https://gcc.gnu.org/PR23624
370. https://gcc.gnu.org/PR23639
371. https://gcc.gnu.org/PR23797
372. https://gcc.gnu.org/PR23965
373. https://gcc.gnu.org/PR24052
374. https://gcc.gnu.org/PR24580
375. https://gcc.gnu.org/PR24267
376. https://gcc.gnu.org/PR17810
377. https://gcc.gnu.org/PR17860
378. https://gcc.gnu.org/PR21709
379. https://gcc.gnu.org/PR21964
380. https://gcc.gnu.org/PR22167
381. https://gcc.gnu.org/PR22619
382. https://gcc.gnu.org/PR23241
383. https://gcc.gnu.org/PR23478
384. https://gcc.gnu.org/PR24470
385. https://gcc.gnu.org/PR24950
386. https://gcc.gnu.org/PR14400
387. https://gcc.gnu.org/PR14940
388. https://gcc.gnu.org/PR20239
389. https://gcc.gnu.org/PR15220
390. https://gcc.gnu.org/PR19275
391. https://gcc.gnu.org/PR21888
392. https://gcc.gnu.org/PR15342
393. https://gcc.gnu.org/PR23985
394. https://gcc.gnu.org/PR16719
395. https://gcc.gnu.org/PR21723
396. https://gcc.gnu.org/PR21841
397. https://gcc.gnu.org/PR23644
398. https://gcc.gnu.org/PR24718
399. https://gcc.gnu.org/PR18421
400. https://gcc.gnu.org/PR20621
401. https://gcc.gnu.org/PR18583
402. https://gcc.gnu.org/PR20191
403. https://gcc.gnu.org/PR22083
404. https://gcc.gnu.org/PR23070
405. https://gcc.gnu.org/PR23404
406. https://gcc.gnu.org/PR23539
407. https://gcc.gnu.org/PR24102
408. https://gcc.gnu.org/PR24465
409. https://gcc.gnu.org/PR19933
410. https://gcc.gnu.org/PR21889
411. https://gcc.gnu.org/PR19300
412. https://gcc.gnu.org/PR20301
413. https://gcc.gnu.org/PR20673
414. https://gcc.gnu.org/PR18582
415. https://gcc.gnu.org/PR19340
416. https://gcc.gnu.org/PR21716
417. https://gcc.gnu.org/PR24315
418. https://gcc.gnu.org/gcc-3.4/changes.html#GCC3.4.6
419. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=3.4.6
420. https://gcc.gnu.org/onlinedocs/
421. mailto:[email protected]
422. mailto:[email protected]
423. https://gcc.gnu.org/lists.html
424. https://www.fsf.org/
425. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-3.3/index.html

GCC 3.3 Release Series

(This release series is no longer supported.)

May 03, 2005

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 3.3.6.

This release is a bug-fix release, containing fixes for regressions in
GCC 3.3.5 relative to previous releases of GCC.

This release is the last of the series 3.3.x.

The GCC 3.3 release series includes numerous [2]new features,
improvements, bug fixes, and other changes, thanks to an [3]amazing
group of volunteers.

Release History

GCC 3.3.6
May 3, 2005 ([4]changes)

GCC 3.3.5
September 30, 2004 ([5]changes)

GCC 3.3.4
May 31, 2004 ([6]changes)

GCC 3.3.3
February 14, 2004 ([7]changes)

GCC 3.3.2
October 16, 2003 ([8]changes)

GCC 3.3.1
August 8, 2003 ([9]changes)

GCC 3.3
May 14, 2003 ([10]changes)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [11]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [12]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [13]GCC
project web site or contact the [14]GCC development mailing list.

To obtain GCC please use [15]our mirror sites, or our CVS server.

For questions related to the use of GCC, please consult these web
pages and the [16]GCC manuals. If that fails, the
[17][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [18][email protected]. All of [19]our lists have public
archives.

Copyright (C) [20]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [21]maintained by the GCC team. Last modified
2022-10-26.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-3.3/changes.html
3. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
4. https://gcc.gnu.org/gcc-3.3/changes.html#3.3.6
5. https://gcc.gnu.org/gcc-3.3/changes.html#3.3.5
6. https://gcc.gnu.org/gcc-3.3/changes.html#3.3.4
7. https://gcc.gnu.org/gcc-3.3/changes.html#3.3.3
8. https://gcc.gnu.org/gcc-3.3/changes.html#3.3.2
9. https://gcc.gnu.org/gcc-3.3/changes.html#3.3.1
10. https://gcc.gnu.org/gcc-3.3/changes.html
11. https://gcc.gnu.org/gcc-3.3/buildstat.html
12. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
13. https://gcc.gnu.org/index.html
14. mailto:[email protected]
15. https://gcc.gnu.org/mirrors.html
16. https://gcc.gnu.org/onlinedocs/
17. mailto:[email protected]
18. mailto:[email protected]
19. https://gcc.gnu.org/lists.html
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======================================================================
http://gcc.gnu.org/gcc-3.3/changes.html

GCC 3.3 Release Series
Changes, New Features, and Fixes

The latest release in the 3.3 release series is [1]GCC 3.3.6.

Caveats

* The preprocessor no longer accepts multi-line string literals. They
were deprecated in 3.0, 3.1, and 3.2.
* The preprocessor no longer supports the -A- switch when appearing
alone. -A- followed by an assertion is still supported.
* Support for all the systems [2]obsoleted in GCC 3.1 has been
removed from GCC 3.3. See below for a [3]list of systems which are
obsoleted in this release.
* Checking for null format arguments has been decoupled from the rest
of the format checking mechanism. Programs which use the format
attribute may regain this functionality by using the new [4]nonnull
function attribute. Note that all functions for which GCC has a
built-in format attribute, an appropriate built-in nonnull
attribute is also applied.
* The DWARF (version 1) debugging format has been deprecated and will
be removed in a future version of GCC. Version 2 of the DWARF
debugging format will continue to be supported for the foreseeable
future.
* The C and Objective-C compilers no longer accept the "Naming Types"
extension (typedef foo = bar); it was already unavailable in C++.
Code which uses it will need to be changed to use the "typeof"
extension instead: typedef typeof(bar) foo. (We have removed this
extension without a period of deprecation because it has caused the
compiler to crash since version 3.0 and no one noticed until very
recently. Thus we conclude it is not in widespread use.)
* The -traditional C compiler option has been removed. It was
deprecated in 3.1 and 3.2. (Traditional preprocessing remains
available.) The <varargs.h> header, used for writing variadic
functions in traditional C, still exists but will produce an error
message if used.
* GCC 3.3.1 automatically places zero-initialized variables in the
.bss section on some operating systems. Versions of GNU Emacs up to
(and including) 21.3 will not work correctly when using this
optimization; you can use -fno-zero-initialized-in-bss to disable
it.

General Optimizer Improvements

* A new scheme for accurately describing processor pipelines, the
[5]DFA scheduler, has been added.
* Pavel Nejedly, Charles University Prague, has contributed new file
format used by the edge coverage profiler (-fprofile-arcs).
The new format is robust and diagnoses common mistakes where
profiles from different versions (or compilations) of the program
are combined resulting in nonsensical profiles and slow code to
produced with profile feedback. Additionally this format allows
extra data to be gathered. Currently, overall statistics are
produced helping optimizers to identify hot spots of a program
globally replacing the old intra-procedural scheme and resulting in
better code. Note that the gcov tool from older GCC versions will
not be able to parse the profiles generated by GCC 3.3 and vice
versa.
* Jan Hubicka, SuSE Labs, has contributed a new superblock formation
pass enabled using -ftracer. This pass simplifies the control flow
of functions allowing other optimizations to do better job.
He also contributed the function reordering pass
(-freorder-functions) to optimize function placement using profile
feedback.

New Languages and Language specific improvements

C/ObjC/C++

* The preprocessor now accepts directives within macro arguments. It
processes them just as if they had not been within macro arguments.
* The separate ISO and traditional preprocessors have been completely
removed. The front end handles either type of preprocessed output
if necessary.
* In C99 mode preprocessor arithmetic is done in the precision of the
target's intmax_t, as required by that standard.
* The preprocessor can now copy comments inside macros to the output
file when the macro is expanded. This feature, enabled using the
-CC option, is intended for use by applications which place
metadata or directives inside comments, such as lint.
* The method of constructing the list of directories to be searched
for header files has been revised. If a directory named by a -I
option is a standard system include directory, the option is
ignored to ensure that the default search order for system
directories and the special treatment of system header files are
not defeated.
* A few more [6]ISO C99 features now work correctly.
* A new function attribute, nonnull, has been added which allows
pointer arguments to functions to be specified as requiring a
non-null value. The compiler currently uses this information to
issue a warning when it detects a null value passed in such an
argument slot.
* A new type attribute, may_alias, has been added. Accesses to
objects with types with this attribute are not subjected to
type-based alias analysis, but are instead assumed to be able to
alias any other type of objects, just like the char type.

C++

* Type based alias analysis has been implemented for C++ aggregate
types.

Objective-C

* Generate an error if Objective-C objects are passed by value in
function and method calls.
* When -Wselector is used, check the whole list of selectors at the
end of compilation, and emit a warning if a @selector() is not
known.
* Define __NEXT_RUNTIME__ when compiling for the NeXT runtime.
* No longer need to include objc/objc-class.h to compile self calls
in class methods (NeXT runtime only).
* New -Wundeclared-selector option.
* Removed selector bloating which was causing object files to be 10%
bigger on average (GNU runtime only).
* Using at run time @protocol() objects has been fixed in certain
situations (GNU runtime only).
* Type checking has been fixed and improved in many situations
involving protocols.

Java

* The java.sql and javax.sql packages now implement the JDBC 3.0 (JDK
1.4) API.
* The JDK 1.4 assert facility has been implemented.
* The bytecode interpreter is now direct threaded and thus faster.

Fortran

* Fortran improvements are listed in [7]the Fortran documentation.

Ada

* Ada tasking now works with glibc 2.3.x threading libraries.

New Targets and Target Specific Improvements

* The following changes have been made to the HP-PA port:
+ The port now defaults to scheduling for the PA8000 series of
processors.
+ Scheduling support for the PA7300 processor has been added.
+ The 32-bit port now supports weak symbols under HP-UX 11.
+ The handling of initializers and finalizers has been improved
under HP-UX 11. The 64-bit port no longer uses collect2.
+ Dwarf2 EH support has been added to the 32-bit GNU/Linux port.
+ ABI fixes to correct the passing of small structures by value.
* The SPARC, HP-PA, SH4, and x86/pentium ports have been converted to
use the DFA processor pipeline description.
* The following NetBSD configurations for the SuperH processor family
have been added:
+ SH3, big-endian, sh-*-netbsdelf*
+ SH3, little-endian, shle-*-netbsdelf*
+ SH5, SHmedia, big-endian, 32-bit default, sh5-*-netbsd*
+ SH5, SHmedia, little-endian, 32-bit default, sh5le-*-netbsd*
+ SH5, SHmedia, big-endian, 64-bit default, sh64-*-netbsd*
+ SH5, SHmedia, little-endian, 64-bit default, sh64le-*-netbsd*
* The following changes have been made to the IA-32/x86-64 port:
+ SSE2 and 3dNOW! intrinsics are now supported.
+ Support for thread local storage has been added to the IA-32
and x86-64 ports.
+ The x86-64 port has been significantly improved.
* The following changes have been made to the MIPS port:
+ All configurations now accept the -mabi switch. Note that you
will need appropriate multilibs for this option to work
properly.
+ ELF configurations will always pass an ABI flag to the
assembler, except when the MIPS EABI is selected.
+ -mabi=64 no longer selects MIPS IV code.
+ The -mcpu option, which was deprecated in 3.1 and 3.2, has
been removed from this release.
+ -march now changes the core ISA level. In previous releases,
it would change the use of processor-specific extensions, but
would leave the core ISA unchanged. For example, mips64-elf
-march=r8000 will now generate MIPS IV code.
+ Under most configurations, -mipsN now acts as a synonym for
-march.
+ There are some new preprocessor macros to describe the -march
and -mtune settings. See the documentation of those options
for details.
+ Support for the NEC VR-Series processors has been added. This
includes the 54xx, 5500, and 41xx series.
+ Support for the Sandcraft sr71k processor has been added.
* The following changes have been made to the S/390 port:
+ Support to build the Java runtime libraries has been added.
Java is now enabled by default on s390-*-linux* and
s390x-*-linux* targets.
+ Multilib support for the s390x-*-linux* target has been added;
this allows to build 31-bit binaries using the -m31 option.
+ Support for thread local storage has been added.
+ Inline assembler code may now use the 'Q' constraint to
specify memory operands without index register.
+ Various platform-specific performance improvements have been
implemented; in particular, the compiler now uses the BRANCH
ON COUNT family of instructions and makes more frequent use of
the TEST UNDER MASK family of instructions.
* The following changes have been made to the PowerPC port:
+ Support for IBM Power4 processor added.
+ Support for Motorola e500 SPE added.
+ Support for AIX 5.2 added.
+ Function and Data sections now supported on AIX.
+ Sibcall optimizations added.
* The support for H8 Tiny is added to the H8/300 port with -mn.

[8]Obsolete Systems

Support for a number of older systems has been declared obsolete in GCC
3.3. Unless there is activity to revive them, the next release of GCC
will have their sources permanently removed.

All configurations of the following processor architectures have been
declared obsolete:
* Matsushita MN10200, mn10200-*-*
* Motorola 88000, m88k-*-*
* IBM ROMP, romp-*-*

Also, some individual systems have been obsoleted:
* Alpha
+ Interix, alpha*-*-interix*
+ Linux libc1, alpha*-*-linux*libc1*
+ Linux ECOFF, alpha*-*-linux*ecoff*
* ARM
+ Generic a.out, arm*-*-aout*
+ Conix, arm*-*-conix*
+ "Old ABI," arm*-*-oabi
+ StrongARM/COFF, strongarm-*-coff*
* HPPA (PA-RISC)
+ Generic OSF, hppa1.0-*-osf*
+ Generic BSD, hppa1.0-*-bsd*
+ HP/UX versions 7, 8, and 9, hppa1.[01]-*-hpux[789]*
+ HiUX, hppa*-*-hiux*
+ Mach Lites, hppa*-*-lites*
* Intel 386 family
+ Windows NT 3.x, i?86-*-win32
* MC68000 family
+ HP systems, m68000-hp-bsd* and m68k-hp-bsd*
+ Sun systems, m68000-sun-sunos*, m68k-sun-sunos*, and
m68k-sun-mach*
+ AT&T systems, m68000-att-sysv*
+ Atari systems, m68k-atari-sysv*
+ Motorola systems, m68k-motorola-sysv*
+ NCR systems, m68k-ncr-sysv*
+ Plexus systems, m68k-plexus-sysv*
+ Commodore systems, m68k-cbm-sysv*
+ Citicorp TTI, m68k-tti-*
+ Unos, m68k-crds-unos*
+ Concurrent RTU, m68k-ccur-rtu*
+ Linux a.out, m68k-*-linux*aout*
+ Linux libc1, m68k-*-linux*libc1*
+ pSOS, m68k-*-psos*
* MIPS
+ Generic ECOFF, mips*-*-ecoff*
+ SINIX, mips-sni-sysv4
+ Orion RTEMS, mips64orion-*-rtems*
* National Semiconductor 32000
+ OpenBSD, ns32k-*-openbsd*
* POWER (aka RS/6000) and PowerPC
+ AIX versions 1, 2, and 3, rs6000-ibm-aix[123]*
+ Bull BOSX, rs6000-bull-bosx
+ Generic Mach, rs6000-*-mach*
+ Generic SysV, powerpc*-*-sysv*
+ Linux libc1, powerpc*-*-linux*libc1*
* Sun SPARC
+ Generic a.out, sparc-*-aout*, sparclet-*-aout*,
sparclite-*-aout*, and sparc86x-*-aout*
+ NetBSD a.out, sparc-*-netbsd*aout*
+ Generic BSD, sparc-*-bsd*
+ ChorusOS, sparc-*-chorusos*
+ Linux a.out, sparc-*-linux*aout*
+ Linux libc1, sparc-*-linux*libc1*
+ LynxOS, sparc-*-lynxos*
+ Solaris on HAL hardware, sparc-hal-solaris2*
+ SunOS versions 3 and 4, sparc-*-sunos[34]*
* NEC V850
+ RTEMS, v850-*-rtems*
* VAX
+ VMS, vax-*-vms*

Documentation improvements

Other significant improvements

* Almost all front-end dependencies in the compiler have been
separated out into a set of language hooks. This should make adding
a new front end clearer and easier.
* One effect of removing the separate preprocessor is a small
increase in the robustness of the compiler in general, and the
maintainability of target descriptions. Previously target-specific
built-in macros and others, such as __FAST_MATH__, had to be
handled with so-called specs that were hard to maintain. Often they
would fail to behave properly when conflicting options were
supplied on the command line, and define macros in the user's
namespace even when strict ISO compliance was requested.
Integrating the preprocessor has cleanly solved these issues.
* The Makefile suite now supports redirection of make install by
means of the variable DESTDIR.
__________________________________________________________________

GCC 3.3

Detailed release notes for the GCC 3.3 release follow.

Bug Fixes

bootstrap failures

* [9]10140 cross compiler build failures: missing __mempcpy (DUP:
[10]10198,[11]10338)

Internal compiler errors (multi-platform)

* [12]3581 large string causes segmentation fault in cc1
* [13]4382 __builtin_{set,long}jmp with -O3 can crash the compiler
* [14]5533 (c++) ICE when processing std::accumulate(begin, end,
init, invalid_op)
* [15]6387 -fpic -gdwarf-2 -g1 combination gives ICE in dwarf2out
* [16]6412 (c++) ICE in retrieve_specialization
* [17]6620 (c++) partial template specialization causes an ICE
(segmentation fault)
* [18]6663 (c++) ICE with attribute aligned
* [19]7068 ICE with incomplete types
* [20]7083 (c++) ICE using -gstabs with dodgy class derivation
* [21]7647 (c++) ICE when data member has the name of the enclosing
class
* [22]7675 ICE in fixup_var_refs_1
* [23]7718 'complex' template instantiation causes ICE
* [24]8116 (c++) ICE in member template function
* [25]8358 (ada) Ada compiler accesses freed memory, crashes
* [26]8511 (c++) ICE: (hopefully) reproducible cc1plus segmentation
fault
* [27]8564 (c++) ICE in find_function_data, in function.c
* [28]8660 (c++) template overloading ICE in tsubst_expr, in cp/pt.c
* [29]8766 (c++) ICE after failed initialization of static template
variable
* [30]8803 ICE in instantiate_virtual_regs_1, in function.c
* [31]8846 (c++) ICE after diagnostic if fr_FR@euro locale is set
* [32]8906 (c++) ICE (Segmentation fault) when parsing nested-class
definition
* [33]9216 (c++) ICE on missing template parameter
* [34]9261 (c++) ICE in arg_assoc, in cp/decl2.c
* [35]9263 (fortran) ICE caused by invalid PARAMETER in implied DO
loop
* [36]9429 (c++) ICE in template instantiation with a pointered new
operator
* [37]9516 Internal error when using a big array
* [38]9600 (c++) ICE with typedefs in template class
* [39]9629 (c++) virtual inheritance segfault
* [40]9672 (c++) ICE: Error reporting routines re-entered
* [41]9749 (c++) ICE in write_expression on invalid function
prototype
* [42]9794 (fortran) ICE: floating point exception during constant
folding
* [43]9829 (c++) Missing colon in nested namespace usage causes ICE
* [44]9916 (c++) ICE with noreturn function in ?: statement
* [45]9936 ICE with local function and variable-length 2d array
* [46]10262 (c++) cc1plus crashes with large generated code
* [47]10278 (c++) ICE in parser for invalid code
* [48]10446 (c++) ICE on definition of nonexistent member function of
nested class in a class template
* [49]10451 (c++) ICE in grokdeclarator on spurious mutable
declaration
* [50]10506 (c++) ICE in build_new at cp/init.c with
-fkeep-inline-functions and multiple inheritance
* [51]10549 (c++) ICE in store_bit_field on bitfields that exceed the
precision of the declared type

Optimization bugs

* [52]2001 Inordinately long compile times in reload CSE regs
* [53]2391 Exponential compilation time explosion in combine
* [54]2960 Duplicate loop conditions even with -Os
* [55]4046 redundant conditional branch
* [56]6405 Loop-unrolling related performance regressions
* [57]6798 very long compile time with large case-statement
* [58]6871 const objects shouldn't be moved to .bss
* [59]6909 problem w/ -Os on modified loop-2c.c test case
* [60]7189 gcc -O2 -Wall does not print ``control reaches end of
non-void function'' warning
* [61]7642 optimization problem with signbit()
* [62]8634 incorrect code for inlining of memcpy under -O2
* [63]8750 Cygwin prolog generation erroneously emitting __alloca as
regular function call

C front end

* [64]2161 long if-else cascade overflows parser stack
* [65]4319 short accepted on typedef'd char
* [66]8602 incorrect line numbers in warning messages when using
inline functions
* [67]9177 -fdump-translation-unit: C front end deletes function_decl
AST nodes and breaks debugging dumps
* [68]9853 miscompilation of non-constant structure initializer

c++ compiler and library

* [69]45 legal template specialization code is rejected (DUP:
[70]3784)
* [71]764 lookup failure: friend operator and dereferencing a pointer
and templates (DUP: [72]5116)
* [73]2862 gcc accepts invalid explicit instantiation syntax (DUP:
2863)
* [74]3663 G++ doesn't check access control during template
instantiation
* [75]3797 gcc fails to emit explicit specialization of a template
member
* [76]3948 Two destructors are called when no copy destructor is
defined (ABI change)
* [77]4137 Conversion operator within template is not accepted
* [78]4361 bogus ambiguity taking the address of a member template
* [79]4802 g++ accepts illegal template code (access to private
member; DUP: [80]5837)
* [81]4803 inline function is used but never defined, and g++ does
not object
* [82]5094 Partial specialization cannot be friend?
* [83]5730 complex<double>::norm() -- huge slowdown from egcs-2.91.66
* [84]6713 Regression wrt 3.0.4: g++ -O2 leads to seg fault at run
time
* [85]7015 certain __asm__ constructs rejected
* [86]7086 compile time regression (quadratic behavior in
fixup_var_refs)
* [87]7099 G++ doesn't set the noreturn attribute on std::exit and
std::abort
* [88]7247 copy constructor missing when inlining enabled (invalid
optimization?)
* [89]7441 string array initialization compilation time regression
from seconds to minutes
* [90]7768 __PRETTY_FUNCTION__ for template destructor is wrong
* [91]7804 bad printing of floating point constant in warning message
* [92]8099 Friend classes and template specializations
* [93]8117 member function pointers and multiple inheritance
* [94]8205 using declaration and multiple inheritance
* [95]8645 unnecessary non-zero checks in stl_tree.h
* [96]8724 explicit destructor call for incomplete class allowed
* [97]8805 compile time regression with many member variables
* [98]8691 -O3 and -fno-implicit-templates are incompatible
* [99]8700 unhelpful error message for binding temp to reference
* [100]8724 explicit destructor call for incomplete class allowed
* [101]8949 numeric_limits<>::denorm_min() and is_iec559 problems
* [102]9016 Failure to consistently constant fold "constant" C++
objects
* [103]9053 g++ confused about ambiguity of overloaded function
templates
* [104]9152 undefined virtual thunks
* [105]9182 basic_filebuf<> does not report errors in codecvt<>::out
* [106]9297 data corruption due to codegen bug (when copying.)
* [107]9318 i/ostream::operator>>/<<(streambuf*) broken
* [108]9320 Incorrect usage of traits_type::int_type in stdio_filebuf
* [109]9400 bogus -Wshadow warning: shadowed declaration of this in
local classes
* [110]9424 i/ostream::operator>>/<<(streambuf*) drops characters
* [111]9425 filebuf::pbackfail broken (DUP: [112]9439)
* [113]9474 GCC freezes in compiling a weird code mixing <iostream>
and <iostream.h>
* [114]9548 Incorrect results from setf(ios::fixed) and precision(-1)
[115][DR 231]
* [116]9555 ostream inserters fail to set badbit on exception
* [117]9561 ostream inserters rethrow exception of wrong type
* [118]9563 ostream::sentry returns true after a failed preparation
* [119]9582 one-definition rule violation in std::allocator
* [120]9622 __PRETTY_FUNCTION__ incorrect in template destructors
* [121]9683 bug in initialization chains for static const variables
from template classes
* [122]9791 -Woverloaded-virtual reports hiding of destructor
* [123]9817 collate::compare doesn't handle nul characters
* [124]9825 filebuf::sputbackc breaks sbumpc
* [125]9826 operator>>(basic_istream, basic_string) fails to compile
with custom traits
* [126]9924 Multiple using statements for builtin functions not
allowed
* [127]9946 destructor is not called for temporary object
* [128]9964 filebuf::close() sometimes fails to close file
* [129]9988 filebuf::overflow writes EOF to file
* [130]10033 optimization breaks polymorphic references w/ typeid
operator
* [131]10097 filebuf::underflow drops characters
* [132]10132 filebuf destructor can throw exceptions
* [133]10180 gcc fails to warn about non-inlined function
* [134]10199 method parametrized by template does not work everywhere
* [135]10300 use of array-new (nothrow) in segfaults on NULL return
* [136]10427 Stack corruption with variable-length automatic arrays
and virtual destructors
* [137]10503 Compilation never stops in fixed_type_or_null

Objective-C

* [138]5956 selectors aren't matched properly when added to the
selector table

Fortran compiler and library

* [139]1832 list directed i/o overflow hangs, -fbounds-check doesn't
detect
* [140]3924 g77 generates code that is rejected by GAS if COFF debug
info requested
* [141]5634 doc: explain that configure --prefix=~/... does not work
* [142]6367 multiple repeat counts confuse namelist read into array
* [143]6491 Logical operations error on logicals when using
-fugly-logint
* [144]6742 Generation of C++ Prototype for FORTRAN and extern "C"
* [145]7113 Failure of g77.f-torture/execute/f90-intrinsic-bit.f -Os
on irix6.5
* [146]7236 OPEN(...,RECL=nnn,...) without ACCESS='DIRECT' should
assume a direct access file
* [147]7278 g77 "bug"; the executable misbehaves (with -O2
-fno-automatic)
* [148]7384 DATE_AND_TIME milliseconds field inactive on Windows
* [149]7388 Incorrect output with 0-based array of characters
* [150]8587 Double complex zero ** double precision number -> NaN
instead of zero
* [151]9038 -ffixed-line-length-none -x f77-cpp-input gives: Warning:
unknown register name line-length-none
* [152]10197 Direct access files not unformatted by default

Java compiler and library

* [153]6005 gcj fails to build rhug on alpha
* [154]6389 System.getProperty("") should always throw an
IllegalArgumentException
* [155]6576 java.util.ResourceBundle.getResource ignores locale
* [156]6652 new java.io.File("").getCanonicalFile() throws exception
* [157]7060 getMethod() doesn't search super interface
* [158]7073 bytecode interpreter gives wrong answer for interface
getSuperclass()
* [159]7180 possible bug in
javax.naming.spi.NamingManager.getPlusPath()
* [160]7416 java.security startup refs "GNU libgcj.security"
* [161]7570 Runtime.exec with null envp: child doesn't inherit parent
env (DUP: [162]7578)
* [163]7611 Internal error while compiling libjava with -O
* [164]7709 NullPointerException in _Jv_ResolvePoolEntry
* [165]7766 ZipInputStream.available returns 0 immediately after
construction
* [166]7785 Calendar.getTimeInMillis/setTimeInMillis should be public
* [167]7786 TimeZone.getDSTSavings() from JDK1.4 not implemented
* [168]8142 '$' in class names vs. dlopen 'dynamic string tokens'
* [169]8234 ZipInputStream chokes when InputStream.read() returns
small chunks
* [170]8415 reflection bug: exception info for Method
* [171]8481 java.Random.nextInt(int) may return negative
* [172]8593 Error reading GZIPped files with BufferedReader
* [173]8759 java.beans.Introspector has no flushCaches() or
flushFromCaches() methods
* [174]8997 spin() calls Thread.sleep
* [175]9253 on win32, java.io.File.listFiles("C:\\") returns pwd
instead of the root content of C:
* [176]9254 java::lang::Object::wait(), threads-win32.cc returns
wrong return codes
* [177]9271 Severe bias in java.security.SecureRandom

Ada compiler and library

* [178]6767 make gnatlib-shared fails on -laddr2line
* [179]9911 gnatmake fails to link when GCC configured with
--with-sjlj-exceptions=yes
* [180]10020 Can't bootstrap gcc on AIX with Ada enabled
* [181]10546 Ada tasking not working on Red Hat 9

preprocessor

* [182]7029 preprocessor should ignore #warning with -M

ARM-specific

* [183]2903 [arm] Optimization bug with long long arithmetic
* [184]7873 arm-linux-gcc fails when assigning address to a bit field

FreeBSD-specific

* [185]7680 float functions undefined in math.h/cmath with #define
_XOPEN_SOURCE

HP-UX or HP-PA-specific

* [186]8705 [HP-PA] ICE in emit_move_insn_1, in expr.c
* [187]9986 [HP-UX] Incorrect transformation of fputs_unlocked to
fputc_unlocked
* [188]10056 [HP-PA] ICE at -O2 when building c++ code from doxygen

m68hc11-specific

* [189]6744 Bad assembler code generated: reference to pseudo
register z
* [190]7361 Internal compiler error in reload_cse_simplify_operands,
in reload1.c

MIPS-specific

* [191]9496 [mips-linux] bug in optimizer?

PowerPC-specific

* [192]7067 -Os with -mcpu=powerpc optimizes for speed (?) instead of
space
* [193]8480 reload ICEs for LAPACK code on powerpc64-linux
* [194]8784 [AIX] Internal compiler error in simplify_gen_subreg
* [195]10315 [powerpc] ICE: in extract_insn, in recog.c

SPARC-specific

* [196]10267 (documentation) Wrong build instructions for
*-*-solaris2*

x86-specific (Intel/AMD)

* [197]7916 ICE in instantiate_virtual_register_1
* [198]7926 (c++) i486 instructions in header files make c++ programs
crash on i386
* [199]8555 ICE in gen_split_1231
* [200]8994 ICE with -O -march=pentium4
* [201]9426 ICE with -fssa -funroll-loops -fprofile-arcs
* [202]9806 ICE in inline assembly with -fPIC flag
* [203]10077 gcc -msse2 generates movd to move dwords between xmm
regs
* [204]10233 64-bit comparison only comparing bottom 32-bits
* [205]10286 type-punning doesn't work with __m64 and -O
* [206]10308 [x86] ICE with -O -fgcse or -O2
__________________________________________________________________

[207]GCC 3.3.1

Bug Fixes

This section lists the problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 3.3.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

Bootstrap failures

* [208]11272 [Solaris] make bootstrap fails while building libstdc++

Internal compiler errors (multi-platform)

* [209]5754 ICE on invalid nested template class
* [210]6597 ICE in set_mem_alias_set compiling Qt with -O2 on ia64
and --enable-checking
* [211]6949 (c++) ICE in tsubst_decl, in cp/pt.c
* [212]7053 (c++) ICE when declaring a function already defined as a
friend method of a template class
* [213]8164 (c++) ICE when using different const expressions as
template parameter
* [214]8384 (c++) ICE in is_base_type, in dwarf2out.c
* [215]9559 (c++) ICE with invalid initialization of a static const
* [216]9649 (c++) ICE in finish_member_declaration, in cp/semantics.c
when redeclaring a static member variable
* [217]9864 (fortran) ICE in add_abstract_origin_attribute, in
dwarfout.c with -g -O -finline-functions
* [218]10432 (c++) ICE in poplevel, in cp/decl.c
* [219]10475 ICE in subreg_highpart_offset for code with long long
* [220]10635 (c++) ICE when dereferencing an incomplete type casted
from a void pointer
* [221]10661 (c++) ICE in instantiate_decl, in cp/pt.c while
instantiating static member variables
* [222]10700 ICE in copy_to_mode_reg on 64-bit targets
* [223]10712 (c++) ICE in constructor_name_full, in cp/decl2.c
* [224]10796 (c++) ICE when defining an enum with two values: -1 and
MAX_INT_64BIT
* [225]10890 ICE in merge_assigned_reloads building Linux 2.4.2x
sched.c
* [226]10939 (c++) ICE with template code
* [227]10956 (c++) ICE when specializing a template member function
of a template class, in tsubst, in cp/pt.c
* [228]11041 (c++) ICE: const myclass &x = *x; (when operator*()
defined)
* [229]11059 (c++) ICE with empty union
* [230]11083 (c++) ICE in commit_one_edge_insertion, in cfgrtl.c with
-O2 -fnon-call-exceptions
* [231]11105 (c++) ICE in mangle_conv_op_name_for_type
* [232]11149 (c++) ICE on error when instantiation with call function
of a base type
* [233]11228 (c++) ICE on new-expression using array operator new and
default-initialization
* [234]11282 (c++) Infinite memory usage after syntax error
* [235]11301 (fortran) ICE with -fno-globals
* [236]11308 (c++) ICE when using an enum type name as if it were a
class or namespace
* [237]11473 (c++) ICE with -gstabs when empty struct inherits from
an empty struct
* [238]11503 (c++) ICE when instantiating template with ADDR_EXPR
* [239]11513 (c++) ICE in push_template_decl_real, in cp/pt.c:
template member functions

Optimization bugs

* [240]11198 -O2 -frename-registers generates wrong code (aliasing
problem)
* [241]11304 Wrong code production with -fomit-frame-pointer
* [242]11381 volatile memory access optimized away
* [243]11536 [strength-reduce] -O2 optimization produces wrong code
* [244]11557 constant folding bug generates wrong code

C front end

* [245]5897 No warning for statement after return
* [246]11279 DWARF-2 output mishandles large enums

Preprocessor bugs

* [247]11022 no warning for non-compatible macro redefinition

C++ compiler and library

* [248]2330 static_cast<>() to a private base is allowed
* [249]5388 Incorrect message "operands to ?: have different types"
* [250]5390 Libiberty fails to demangle multi-digit template
parameters
* [251]7877 Incorrect parameter passing to specializations of member
function templates
* [252]9393 Anonymous namespaces and compiling the same file twice
* [253]10032 -pedantic converts some errors to warnings
* [254]10468 const typeof(x) is non-const, but only in templates
* [255]10527 confused error message with "new int()" parameter
initializer
* [256]10679 parameter MIN_INLINE_INSNS is not honored
* [257]10682 gcc chokes on a typedef for an enum inside a class
template
* [258]10689 pow(std::complex(0),1/3) returns (nan, nan) instead of
0.
* [259]10845 template member function (with nested template as
parameter) cannot be called anymore if another unrelated template
member function is defined
* [260]10849 Cannot define an out-of-class specialization of a
private nested template class
* [261]10888 Suppress -Winline warnings for system headers
* [262]10929 -Winline warns about functions for which no definition
is visible
* [263]10931 valid conversion static_cast<const unsigned
int&>(lvalue-of-type-int) is rejected
* [264]10940 Bad code with explicit specialization
* [265]10968 If member function implicitly instantiated, explicit
instantiation of class fails to instantiate it
* [266]10990 Cannot convert with dynamic_cast<> to a private base
class from within a member function
* [267]11039 Bad interaction between implicit typename deprecation
and friendship
* [268]11062 (libstdc++) avoid __attribute__ ((unused)); say
"__unused__" instead
* [269]11095 C++ iostream manipulator causes segfault when called
with negative argument
* [270]11098 g++ doesn't emit complete debugging information for
local variables in destructors
* [271]11137 GNU/Linux shared library constructors not called unless
there's one global object
* [272]11154 spurious ambiguity report for template class
specialization
* [273]11329 Compiler cannot find user defined implicit typecast
* [274]11332 Spurious error with casts in ?: expression
* [275]11431 static_cast behavior with subclasses when default
constructor available
* [276]11528 money_get facet does not accept "$.00" as valid
* [277]11546 Type lookup problems in out-of-line definition of a
class doubly nested from a template class
* [278]11567 C++ code containing templated member function with same
name as pure virtual member function results in linking failure
* [279]11645 Failure to deal with using and private inheritance

Java compiler and library

* [280]5179 Qualified static field access doesn't initialize its
class
* [281]8204 gcj -O2 to native reorders certain instructions
improperly
* [282]10838 java.io.ObjectInputStream syntax error
* [283]10886 The RMI registry that comes with GCJ does not work
correctly
* [284]11349 JNDI URL context factories not located correctly

x86-specific (Intel/AMD)

* [285]4823 ICE on inline assembly code
* [286]8878 miscompilation with -O and SSE
* [287]9815 (c++ library) atomicity.h - fails to compile with -O3
-masm=intel
* [288]10402 (inline assembly) [x86] ICE in merge_assigned_reloads,
in reload1.c
* [289]10504 ICE with SSE2 code and -O3 -mcpu=pentium4 -msse2
* [290]10673 ICE for x86-64 on freebsd libc vfprintf.c source
* [291]11044 [x86] out of range loop instructions for FP code on K6
* [292]11089 ICE: instantiate_virtual_regs_lossage while using SSE
built-ins
* [293]11420 [x86_64] gcc generates invalid asm code when "-O -fPIC"
is used

SPARC- or Solaris- specific

* [294]9362 solaris 'as' dies when fed .s and "-gstabs"
* [295]10142 [SPARC64] gcc produces wrong code when passing
structures by value
* [296]10663 New configure check aborts with Sun tools.
* [297]10835 combinatorial explosion in scheduler on HyperSPARC
* [298]10876 ICE in calculate_giv_inc when building KDE
* [299]10955 wrong code at -O3 for structure argument in context of
structure return
* [300]11018 -mcpu=ultrasparc busts tar-1.13.25
* [301]11556 [sparc64] ICE in gen_reg_rtx() while compiling 2.6.x
Linux kernel

ia64 specific

* [302]10907 gcc violates the ia64 ABI (GP must be preserved)
* [303]11320 scheduler bug (in machine depended reorganization pass)
* [304]11599 bug with conditional and __builtin_prefetch

PowerPC specific

* [305]9745 [powerpc] gcc mis-compiles libmcrypt (alias problem
during loop)
* [306]10871 error in rs6000_stack_info save_size computation
* [307]11440 gcc mis-compiles c++ code (libkhtml) with -O2, -fno-gcse
cures it

m68k-specific

* [308]7594 [m68k] ICE on legal code associated with simplify-rtx
* [309]10557 [m68k] ICE in subreg_offset_representable_p
* [310]11054 [m68k] ICE in reg_overlap_mentioned_p

ARM-specific

* [311]10834 [arm] GCC 3.3 still generates incorrect instructions for
functions with __attribute__ ((interrupt ("IRQ")))
* [312]10842 [arm] Clobbered link register is copied to pc under
certain circumstances
* [313]11052 [arm] noce_process_if_block() can lose REG_INC notes
* [314]11183 [arm] ICE in change_address_1 (3.3) / subreg_hard_regno
(3.4)

MIPS-specific

* [315]11084 ICE in propagate_one_insn, in flow.c

SH-specific

* [316]10331 can't compile c++ part of gcc cross compiler for sh-elf
* [317]10413 [SH] ICE in reload_cse_simplify_operands, in reload1.c
* [318]11096 i686-linux to sh-linux cross compiler fails to compile
C++ files

GNU/Linux (or Hurd?) specific

* [319]2873 Bogus fixinclude of stdio.h from glibc 2.2.3

UnixWare specific

* [320]3163 configure bug: gcc/aclocal.m4 mmap test fails on UnixWare
7.1.1

Cygwin (or mingw) specific

* [321]5287 ICE with dllimport attribute
* [322]10148 [MingW/CygWin] Compiler dumps core

DJGPP specific

* [323]8787 GCC fails to emit .intel_syntax when invoked with
-masm=intel on DJGPP

Darwin (and MacOS X) specific

* [324]10900 trampolines crash

Documentation

* [325]1607 (c++) Format attributes on methods undocumented
* [326]4252 Invalid option `-fdump-translation-unit'
* [327]4490 Clarify restrictions on -m96bit-long-double,
-m128bit-long-double
* [328]10355 document an issue with regparm attribute on some systems
(e.g. Solaris)
* [329]10726 (fortran) Documentation for function "IDate Intrinsic
(Unix)" is wrong
* [330]10805 document bug in old version of Sun assembler
* [331]10815 warn against GNU binutils on AIX
* [332]10877 document need for newer binutils on i?86-*-linux-gnu
* [333]11280 Manual incorrect with respect to -freorder-blocks
* [334]11466 Document -mlittle-endian and its restrictions for the
sparc64 port

Testsuite bugs (compiler itself is not affected)

* [335]10737 newer bison causes g++.dg/parse/crash2.C to incorrectly
report failure
* [336]10810 gcc-3.3 fails make check: buffer overrun in
test_demangle.c
__________________________________________________________________

[337]GCC 3.3.2

Bug Fixes

This section lists the problem reports (PRs) from GCC's bug tracker
that are known to be fixed in the 3.3.2 release. This list might not be
complete (that is, it is possible that some PRs that have been fixed
are not listed here).

Bootstrap failures and problems

* [338]8336 [SCO5] bootstrap config still tries to use COFF options
* [339]9330 [alpha-osf] Bootstrap failure on Compaq Tru64 with
--enable-threads=posix
* [340]9631 [hppa64-linux] gcc-3.3 fails to bootstrap
* [341]9877 fixincludes makes a bad sys/byteorder.h on svr5 (UnixWare
7.1.1)
* [342]11687 xstormy16-elf build fails in libf2c
* [343]12263 [SGI IRIX] bootstrap fails during compile of
libf2c/libI77/backspace.c
* [344]12490 buffer overflow in scan-decls.c (during Solaris 9
fix-header processing)

Internal compiler errors (multi-platform)

* [345]7277 Casting integers to vector types causes ICE
* [346]7939 (c++) ICE on invalid function template specialization
* [347]11063 (c++) ICE on parsing initialization list of const array
member
* [348]11207 ICE with negative index in array element designator
* [349]11522 (fortran) g77 dwarf-2 ICE in
add_abstract_origin_attribute
* [350]11595 (c++) ICE on duplicate label definition
* [351]11646 (c++) ICE in commit_one_edge_insertion with
-fnon-call-exceptions -fgcse -O
* [352]11665 ICE in struct initializer when taking address
* [353]11852 (c++) ICE with bad struct initializer.
* [354]11878 (c++) ICE in cp_expr_size
* [355]11883 ICE with any -O on mercury-generated C code
* [356]11991 (c++) ICE in cxx_incomplete_type_diagnostic, in
cp/typeck2.c when applying typeid operator to template template
parameter
* [357]12146 ICE in lookup_template_function, in cp/pt.c
* [358]12215 ICE in make_label_edge with -fnon-call-exceptions
-fno-gcse -O2
* [359]12369 (c++) ICE with templates and friends
* [360]12446 ICE in emit_move_insn on complicated array reference
* [361]12510 ICE in final_scan_insn
* [362]12544 ICE with large parameters used in nested functions

C and optimization bugs

* [363]9862 spurious warnings with -W -finline-functions
* [364]10962 lookup_field is a linear search on a linked list (can be
slow if large struct)
* [365]11370 -Wunreachable-code gives false complaints
* [366]11637 invalid assembly with -fnon-call-exceptions
* [367]11885 Problem with bitfields in packed structs
* [368]12082 Inappropriate unreachable code warnings
* [369]12180 Inline optimization fails for variadic function
* [370]12340 loop unroller + gcse produces wrong code

C++ compiler and library

* [371]3907 nested template parameter collides with member name
* [372]5293 confusing message when binding a temporary to a reference
* [373]5296 [DR115] Pointers to functions and to template functions
behave differently in deduction
* [374]7939 ICE on function template specialization
* [375]8656 Unable to assign function with __attribute__ and pointer
return type to an appropriate variable
* [376]10147 Confusing error message for invalid template function
argument
* [377]11400 std::search_n() makes assumptions about Size parameter
* [378]11409 issues with using declarations, overloading, and
built-in functions
* [379]11740 ctype<wchar_t>::do_is(mask, wchar_t) doesn't handle
multiple bits in mask
* [380]11786 operator() call on variable in other namespace not
recognized
* [381]11867 static_cast ignores ambiguity
* [382]11928 bug with conversion operators that are typedefs
* [383]12114 Uninitialized memory accessed in dtor
* [384]12163 static_cast + explicit constructor regression
* [385]12181 Wrong code with comma operator and c++
* [386]12236 regparm and fastcall messes up parameters
* [387]12266 incorrect instantiation of unneeded template during
overload resolution
* [388]12296 istream::peek() doesn't set eofbit
* [389]12298 [sjlj exceptions] Stack unwind destroys
not-yet-constructed object
* [390]12369 ICE with templates and friends
* [391]12337 apparently infinite loop in g++
* [392]12344 stdcall attribute ignored if function returns a pointer
* [393]12451 missing(late) class forward declaration in cxxabi.h
* [394]12486 g++ accepts invalid use of a qualified name

x86 specific (Intel/AMD)

* [395]8869 [x86 MMX] ICE with const variable optimization and MMX
builtins
* [396]9786 ICE in fixup_abnormal_edges with -fnon-call-exceptions
-O2
* [397]11689 g++3.3 emits un-assembleable code for k6 architecture
* [398]12116 [k6] Invalid assembly output values with X-MAME code
* [399]12070 ICE converting between double and long double with
-msoft-float

ia64-specific

* [400]11184 [ia64 hpux] ICE on __builtin_apply building libobjc
* [401]11535 __builtin_return_address may not work on ia64
* [402]11693 [ia64] ICE in gen_nop_type
* [403]12224 [ia64] Thread-local storage doesn't work

PowerPC-specific

* [404]11087 [powerpc64-linux] GCC miscompiles raid1.c from linux
kernel
* [405]11319 loop miscompiled on ppc32
* [406]11949 ICE Compiler segfault with ffmpeg -maltivec code

SPARC-specific

* [407]11662 wrong code for expr. with cast to long long and
exclusive or
* [408]11965 invalid assembler code for a shift < 32 operation
* [409]12301 (c++) stack corruption when a returned expression throws
an exception

Alpha-specific

* [410]11717 [alpha-linux] unrecognizable insn compiling for.c of
kernel 2.4.22-pre8

HPUX-specific

* [411]11313 problem with #pragma weak and static inline functions
* [412]11712 __STDC_EXT__ not defined for C++ by default anymore?

Solaris specific

* [413]12166 Profiled programs crash if PROFDIR is set

Solaris-x86 specific

* [414]12101 i386 Solaris no longer works with GNU as?

Miscellaneous embedded target-specific bugs

* [415]10988 [m32r-elf] wrong blockmove code with -O3
* [416]11805 [h8300-unknown-coff] [H8300] ICE for simple code with
-O2
* [417]11902 [sh4] spec file improperly inserts rpath even when none
needed
* [418]11903 [sh4] -pthread fails to link due to error in spec file
on sh4
__________________________________________________________________

[419]GCC 3.3.3

Minor features

In addition to the bug fixes documented below, this release contains
few minor features such as:
* Support for --with-sysroot
* Support for automatic detection of executable stacks
* Support for SSE3 instructions
* Support for thread local storage debugging under GDB on S390

Bug Fixes

This section lists the problem reports (PRs) from GCC's bug tracker
that are known to be fixed in the 3.3.3 release. This list might not be
complete (that is, it is possible that some PRs that have been fixed
are not listed here).

Bootstrap failures and issues

* [420]11890 Building cross gcc-3.3.1 for sparc-sun-solaris2.6 fails
* [421]12399 boehm-gc fails (when building a cross compiler): libtool
unable to infer tagged configuration
* [422]13068 mklibgcc.in doesn't handle multi-level multilib
subdirectories properly

Internal compiler errors (multi-platform)

* [423]10060 ICE (stack overflow) on huge file (300k lines) due to
recursive behaviour of copy_rtx_if_shared, in emit_rtl.c
* [424]10555 (c++) ICE on undefined template argument
* [425]10706 (c++) ICE in mangle_class_name_for_template
* [426]11496 (fortran) error in flow_loops_find when -funroll-loops
active
* [427]11741 ICE in pre_insert_copy_insn, in gcse.c
* [428]12440 GCC crashes during compilation of quicktime4linux 2.0.0
* [429]12632 (fortran) -fbounds-check ICE
* [430]12712 (c++) ICE on short legit C++ code fragment with gcc
3.3.2
* [431]12726 (c++) ICE (segfault) on trivial code
* [432]12890 (c++) ICE on compilation of class with throwing method
* [433]12900 (c++) ICE in rtl_verify_flow_info_1
* [434]13060 (fortran) ICE in fixup_var_refs_1, in function.c on
correct code with -O2 -fno-force-mem
* [435]13289 (c++) ICE in regenerate_decl_from_template on recursive
template
* [436]13318 ICE: floating point exception in the loop optimizer
* [437]13392 (c++) ICE in convert_from_eh_region_ranges_1, in
except.c
* [438]13574 (c++) invalid array default initializer in class lets
gcc consume all memory and die
* [439]13475 ICE on SIMD variables with partial value initialization
* [440]13797 (c++) ICE on invalid template parameter
* [441]13824 (java) gcj SEGV with simple .java program

C and optimization bugs

* [442]8776 loop invariants are not removed (most likely)
* [443]10339 [sparc,ppc,ppc64] Invalid optimization: replacing
strncmp by memcmp
* [444]11350 undefined labels with -Os -fPIC
* [445]12826 Optimizer removes reference through volatile pointer
* [446]12500 stabs debug info: void no longer a predefined / builtin
type
* [447]12941 builtin-bitops-1.c miscompilation (latent bug)
* [448]12953 tree inliner bug (in inline_forbidden_p) and fix
* [449]13041 linux-2.6/sound/core/oss/rate.c miscompiled
* [450]13507 spurious printf format warning
* [451]13382 Type information for const pointer disappears during
optimization.
* [452]13394 noreturn attribute ignored on recursive invokation
* [453]13400 Compiled code crashes storing to read-only location
* [454]13521 Endless loop in calculate_global_regs_live

C++ compiler and library

Some of the bug fixes in this list were made to implement decisions
that the ISO C++ standards committee has made concerning several defect
reports (DRs). Links in the list below point to detailed discussion of
the relevant defect report.
* [455]2094 unimplemented: use of `ptrmem_cst' in template type
unification
* [456]2294 using declaration confusion
* [457]5050 template instantiation depth exceeds limit: recursion
problem?
* [458]9371 Bad exception handling in
i/ostream::operator>>/<<(streambuf*)
* [459]9546 bad exception handling in ostream members
* [460]10081 basic_ios::_M_cache_locale leaves NULL members in the
face of unknown locales
* [461]10093 [462][DR 61] Setting failbit in exceptions doesn't work
* [463]10095 istream::operator>>(int&) sets ios::badbit when
ios::failbit is set.
* [464]11554 Warning about reordering of initializers doesn't mention
location of constructor
* [465]12297 istream::sentry::sentry() handles eof() incorrectly.
* [466]12352 Exception safety problems in src/localename.cc
* [467]12438 Memory leak in locale::combine()
* [468]12540 Memory leak in locale::locale(const char*)
* [469]12594 DRs [470]60 [TC] and [471]63 [TC] not implemented
* [472]12657 Resolution of [473]DR 292 (WP) still unimplemented
* [474]12696 memory eating infinite loop in diagnostics (error
recovery problem)
* [475]12815 Code compiled with optimization behaves unexpectedly
* [476]12862 Conflicts between typedefs/enums and namespace member
declarations
* [477]12926 Wrong value after assignment in initialize list using
bit-fields
* [478]12967 Resolution of [479]DR 300 [WP] still unimplemented
* [480]12971 Resolution of [481]DR 328 [WP] still unimplemented
* [482]13007 basic_streambuf::pubimbue, imbue wrong
* [483]13009 Implicitly-defined assignment operator writes to wrong
memory
* [484]13057 regparm attribute not applied to destructor
* [485]13070 -Wformat option ignored in g++
* [486]13081 forward template declarations in <complex> let inlining
fail
* [487]13239 Assertion does not seem to work correctly anymore
* [488]13262 "xxx is private within this context" when initializing a
self-contained template class
* [489]13290 simple typo in concept checking for std::generate_n
* [490]13323 Template code does not compile in presence of typedef
* [491]13369 __verify_grouping (and __add_grouping?) not correct
* [492]13371 infinite loop with packed struct and inlining
* [493]13445 Template argument replacement "dereferences" a typedef
* [494]13461 Fails to access protected-ctor from public constant
* [495]13462 Non-standard-conforming type set::pointer
* [496]13478 gcc uses wrong constructor to initialize a const
reference
* [497]13544 "conflicting types" for enums in different scopes
* [498]13650 string::compare should not (always) use
traits_type::length()
* [499]13683 bogus warning about passing non-PODs through ellipsis
* [500]13688 Derived class is denied access to protected base class
member class
* [501]13774 Member variable cleared in virtual multiple inheritance
class
* [502]13884 Protect sstream.tcc from extern template use

Java compiler and library

* [503]10746 [win32] garbage collection crash in GCJ

Objective-C compiler and library

* [504]11433 Crash due to dereferencing null pointer when querying
protocol

Fortran compiler and library

* [505]12633 logical expression gives incorrect result with
-fugly-logint option
* [506]13037 [gcse-lm] g77 generates incorrect code
* [507]13213 Hex constant problem when compiling with -fugly-logint
and -ftypeless-boz

x86-specific (Intel/AMD)

* [508]4490 ICE with -m128bit-long-double
* [509]12292 [x86_64] ICE: RTL check: expected code `const_int', have
`reg' in make_field_assignment, in combine.c
* [510]12441 ICE: can't find a register to spill
* [511]12943 array static-init failure under -fpic, -fPIC
* [512]13608 Incorrect code with -O3 -ffast-math

PowerPC-specific

* [513]11598 testcase gcc.dg/20020118-1.c fails runtime check of
__attribute__((aligned(16)))
* [514]11793 ICE in extract_insn, in recog.c (const_vector's)
* [515]12467 vmsumubm emitted when vmsummbm appropriate (typo in
altivec.md)
* [516]12537 g++ generates writeable text sections

SPARC-specific

* [517]12496 wrong result for __atomic_add(&value, -1) when using -O0
-m64
* [518]12865 mprotect call to make trampoline executable may fail
* [519]13354 ICE in sparc_emit_set_const32

ARM-specific

* [520]10467 [arm] ICE in pre_insert_copy_insn,

ia64-specific

* [521]11226 ICE passing struct arg with two floats
* [522]11227 ICE for _Complex float, _Complex long double args
* [523]12644 GCC 3.3.2 fails to compile glibc on ia64
* [524]13149 build gcc-3.3.2 1305 error:unrecognizable insn
* Various fixes for libunwind

Alpha-specific

* [525]12654 Incorrect comparison code generated for Alpha
* [526]12965 SEGV+ICE in cc1plus on alpha-linux with -O2
* [527]13031 ICE (unrecognizable insn) when building gnome-libs-1.4.2

HPPA-specific

* [528]11634 [hppa] ICE in verify_local_live_at_start, in flow.c
* [529]12158 [hppa] compilation does not terminate at -O1

S390-specific

* [530]11992 Wrong built-in code for memcmp with length 1<<24: only
(1<<24)-1 possible for CLCL-Instruction

SH-specific

* [531]9365 segfault in gen_far_branch (config/sh/sh.c)
* [532]10392 optimizer generates faulty array indexing
* [533]11322 SH profiler outputs multiple definitions of symbol
* [534]13069 gcc/config/sh/rtems.h broken
* [535]13302 Putting a va_list in a struct causes seg fault
* [536]13585 Incorrect optimization of call to sfunc
* Fix inappropriately exported libgcc functions from the shared
library

Other embedded target specific

* [537]8916 [mcore] unsigned char assign gets hosed.
* [538]11576 [h8300] ICE in change_address_1, in emit-rtl.c
* [539]13122 [h8300] local variable gets corrupted by function call
when -fomit-frame-pointer is given
* [540]13256 [cris] strict_low_part mistreated in delay slots
* [541]13373 [mcore] optimization with -frerun-cse-after-loop
-fexpensive-optimizations produces wrong code on mcore

GNU HURD-specific

* [542]12561 gcc/config/t-gnu needs updating to work with
--with-sysroot

Tru64 Unix specific

* [543]6243 testsuite fails almost all tests due to no libintl in
LD_LIBRARY_PATH during test.
* [544]11397 weak aliases broken on Tru64 UNIX

AIX-specific

* [545]12505 build failure due to defines of uchar in cpphash.h and
sys/types.h
* [546]13150 WEAK symbols not exported by collect2

IRIX-specific

* [547]12666 fixincludes problem on IRIX 6.5.19m

Solaris-specific

* [548]12969 Including sys/byteorder.h breaks configure checks

Testsuite problems (compiler is not affected)

* [549]10819 testsuite creates CR+LF on compiler version lines in
test summary files
* [550]11612 abi_check not finding correct libgcc_s.so.1

Miscellaneous

* [551]13211 using -###, incorrect warnings about unused linker file
are produced
__________________________________________________________________

[552]GCC 3.3.4

This is the [553]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 3.3.4 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).
__________________________________________________________________

[554]GCC 3.3.5

This is the [555]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 3.3.5 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).
__________________________________________________________________

[556]GCC 3.3.6

This is the [557]list of problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 3.3.6 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here).

For questions related to the use of GCC, please consult these web
pages and the [558]GCC manuals. If that fails, the
[559][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [560][email protected]. All of [561]our lists have public
archives.

Copyright (C) [562]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [563]maintained by the GCC team. Last modified
2025-06-05.

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455. https://gcc.gnu.org/PR2094
456. https://gcc.gnu.org/PR2294
457. https://gcc.gnu.org/PR5050
458. https://gcc.gnu.org/PR9371
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461. https://gcc.gnu.org/PR10093
462. https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#61
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471. https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#63
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478. https://gcc.gnu.org/PR12967
479. https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html
480. https://gcc.gnu.org/PR12971
481. https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#328
482. https://gcc.gnu.org/PR13007
483. https://gcc.gnu.org/PR13009
484. https://gcc.gnu.org/PR13057
485. https://gcc.gnu.org/PR13070
486. https://gcc.gnu.org/PR13081
487. https://gcc.gnu.org/PR13239
488. https://gcc.gnu.org/PR13262
489. https://gcc.gnu.org/PR13290
490. https://gcc.gnu.org/PR13323
491. https://gcc.gnu.org/PR13369
492. https://gcc.gnu.org/PR13371
493. https://gcc.gnu.org/PR13445
494. https://gcc.gnu.org/PR13461
495. https://gcc.gnu.org/PR13462
496. https://gcc.gnu.org/PR13478
497. https://gcc.gnu.org/PR13544
498. https://gcc.gnu.org/PR13650
499. https://gcc.gnu.org/PR13683
500. https://gcc.gnu.org/PR13688
501. https://gcc.gnu.org/PR13774
502. https://gcc.gnu.org/PR13884
503. https://gcc.gnu.org/PR10746
504. https://gcc.gnu.org/PR11433
505. https://gcc.gnu.org/PR12633
506. https://gcc.gnu.org/PR13037
507. https://gcc.gnu.org/PR13213
508. https://gcc.gnu.org/PR4490
509. https://gcc.gnu.org/PR12292
510. https://gcc.gnu.org/PR12441
511. https://gcc.gnu.org/PR12943
512. https://gcc.gnu.org/PR13608
513. https://gcc.gnu.org/PR11598
514. https://gcc.gnu.org/PR11793
515. https://gcc.gnu.org/PR12467
516. https://gcc.gnu.org/PR12537
517. https://gcc.gnu.org/PR12496
518. https://gcc.gnu.org/PR12865
519. https://gcc.gnu.org/PR13354
520. https://gcc.gnu.org/PR10467
521. https://gcc.gnu.org/PR11226
522. https://gcc.gnu.org/PR11227
523. https://gcc.gnu.org/PR12644
524. https://gcc.gnu.org/PR13149
525. https://gcc.gnu.org/PR12654
526. https://gcc.gnu.org/PR12965
527. https://gcc.gnu.org/PR13031
528. https://gcc.gnu.org/PR11634
529. https://gcc.gnu.org/PR12158
530. https://gcc.gnu.org/PR11992
531. https://gcc.gnu.org/PR9365
532. https://gcc.gnu.org/PR10392
533. https://gcc.gnu.org/PR11322
534. https://gcc.gnu.org/PR13069
535. https://gcc.gnu.org/PR13302
536. https://gcc.gnu.org/PR13585
537. https://gcc.gnu.org/PR8916
538. https://gcc.gnu.org/PR11576
539. https://gcc.gnu.org/PR13122
540. https://gcc.gnu.org/PR13256
541. https://gcc.gnu.org/PR13373
542. https://gcc.gnu.org/PR12561
543. https://gcc.gnu.org/PR6243
544. https://gcc.gnu.org/PR11397
545. https://gcc.gnu.org/PR12505
546. https://gcc.gnu.org/PR13150
547. https://gcc.gnu.org/PR12666
548. https://gcc.gnu.org/PR12969
549. https://gcc.gnu.org/PR10819
550. https://gcc.gnu.org/PR11612
551. https://gcc.gnu.org/PR13211
552. https://gcc.gnu.org/gcc-3.3/changes.html#GCC3.3.4
553. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=3.3.4
554. https://gcc.gnu.org/gcc-3.3/changes.html#GCC3.3.5
555. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=3.3.5
556. https://gcc.gnu.org/gcc-3.3/changes.html#GCC3.3.6
557. https://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=3.3.6
558. https://gcc.gnu.org/onlinedocs/
559. mailto:[email protected]
560. mailto:[email protected]
561. https://gcc.gnu.org/lists.html
562. https://www.fsf.org/
563. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-3.2/index.html

GCC 3.2 Release Series

(This release series is no longer supported.)

April 25, 2003

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 3.2.3.

The purpose of the GCC 3.2 release series is to provide a stable
platform for OS distributors to use building their next releases. A
primary objective was to stabilize the C++ ABI; we believe that the
interface to the compiler and the C++ standard library are now
relatively stable.

Be aware that C++ code compiled by GCC 3.2.x will (in general) not
interoperate with code compiled by GCC 3.1.1 or earlier.

Please refer to our [2]detailed list of news, caveats, and bug-fixes
for further information.

Release History

GCC 3.2.3
April 25, 2003 ([3]changes)

GCC 3.2.2
February 5, 2003 ([4]changes)

GCC 3.2.1
November 19, 2002 ([5]changes)

GCC 3.2
August 14, 2002 ([6]changes)

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [7]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, improvements, bug fixes, and other changes as
well as test results to GCC. This [8]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [9]GCC project
web site or contact the [10]GCC development mailing list.

To obtain GCC please use [11]our mirror sites, or our CVS server.

For questions related to the use of GCC, please consult these web
pages and the [12]GCC manuals. If that fails, the
[13][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [14][email protected]. All of [15]our lists have public
archives.

Copyright (C) [16]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [17]maintained by the GCC team. Last modified
2022-10-26.

References

1. http://www.gnu.org/
2. https://gcc.gnu.org/gcc-3.2/changes.html
3. https://gcc.gnu.org/gcc-3.2/changes.html#3.2.3
4. https://gcc.gnu.org/gcc-3.2/changes.html#3.2.2
5. https://gcc.gnu.org/gcc-3.2/changes.html#3.2.1
6. https://gcc.gnu.org/gcc-3.2/changes.html#3.2
7. https://gcc.gnu.org/gcc-3.2/buildstat.html
8. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
9. https://gcc.gnu.org/index.html
10. mailto:[email protected]
11. https://gcc.gnu.org/mirrors.html
12. https://gcc.gnu.org/onlinedocs/
13. mailto:[email protected]
14. mailto:[email protected]
15. https://gcc.gnu.org/lists.html
16. https://www.fsf.org/
17. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-3.2/changes.html

GCC 3.2 Release Series
Changes, New Features, and Fixes

The latest release in the 3.2 release series is [1]GCC 3.2.3.

Caveats and New Features

Caveats

* The C++ compiler does not correctly zero-initialize
pointers-to-data members. You must explicitly initialize them. For
example: int S::*m(0); will work, but depending on
default-initialization to zero will not work. This bug cannot be
fixed in GCC 3.2 without inducing unacceptable risks. It will be
fixed in GCC 3.3.
* This GCC release is based on the GCC 3.1 sourcebase, and thus has
all the [2]changes in the GCC 3.1 series. In addition, GCC 3.2 has
a number of C++ ABI fixes which make its C++ compiler generate
binary code which is incompatible with the C++ compilers found in
earlier GCC releases, including GCC 3.1 and GCC 3.1.1.

Frontend Enhancements

C/C++/Objective-C

* The method of constructing the list of directories to be searched
for header files has been revised. If a directory named by a -I
option is a standard system include directory, the option is
ignored to ensure that the default search order for system
directories and the special treatment of system header files are
not defeated.
* The C and Objective-C compilers no longer accept the "Naming Types"
extension (typedef foo = bar); it was already unavailable in C++.
Code which uses it will need to be changed to use the "typeof"
extension instead: typedef typeof(bar) foo. (We have removed this
extension without a period of deprecation because it has caused the
compiler to crash since version 3.0 and no one noticed until very
recently. Thus we conclude it is not in widespread use.)

C++

* GCC 3.2 fixed several differences between the C++ ABI implemented
in GCC and the multi-vendor standard, but more have been found
since the release. 3.2.1 adds a new warning, -Wabi, to warn about
code which is affected by these bugs. We will fix these bugs in
some future release, once we are confident that all have been
found; until then, it is our intention to make changes to the ABI
only if they are necessary for correct compilation of C++, as
opposed to conformance to the ABI documents.
* For details on how to build an ABI compliant compiler for GNU/Linux
systems, check the [3]common C++ ABI page.

New Targets and Target Specific Improvements

IA-32

* Fixed a number of bugs in SSE and MMX intrinsics.
* Fixed common compiler crashes with SSE instruction set enabled
(implied by -march=pentium3, pentium4, athlon-xp)
* __m128 and __m128i is not 128bit aligned when used in structures.

x86-64

* A bug whereby the compiler could generate bad code for bzero has
been fixed.
* ABI fixes (implying ABI incompatibilities with previous version in
some corner cases)
* Fixed prefetch code generation
__________________________________________________________________

[4]GCC 3.2.3

3.2.3 is a bug fix release only; there are no new features that were
not present in GCC 3.2.2.

Bug Fixes

This section lists the problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 3.2.3 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here), and some of the titles have been changed to
make them more clear.

Internal Compiler Errors (multi-platform)

* [5]3782: (c++) -quiet -fstats produces a segmentation fault in
cc1plus
* [6]6440: (c++) template specializations cause ICE
* [7]7050: (c++) ICE on: (i ? get_string() : throw)
* [8]7741: ICE on conflicting types (make_decl_rtl in varasm.c)
* [9]7982: (c++) ICE due to infinite recursion (using STL set)
* [10]8068: exceedingly high (infinite) memory usage
* [11]8178: ICE with __builtin_ffs
* [12]8396: ICE in copy_to_mode_reg, in explow.c
* [13]8674: (c++) ICE in cp_expr_size, in cp/cp-lang.c
* [14]9768: ICE when optimizing inline code at -O2
* [15]9798: (c++) Infinite recursion (segfault) in
cp/decl.c:push_using_directive with recursive using directives
* [16]9799: mismatching structure initializer with nested flexible
array member: ICE
* [17]9928: ICE on duplicate enum declaration
* [18]10114: ICE in mem_loc_descriptor, in dwarf2out.c (affects
sparc, alpha)
* [19]10352: ICE in find_reloads_toplev
* [20]10336: ICE with -Wunreachable-code

C/optimizer bugs:

* [21]8224: Incorrect joining of signed and unsigned division
* [22]8613: -O2 produces wrong code with builtin strlen and
postincrements
* [23]8828: gcc reports some code is unreachable when it is not
* [24]9226: GCSE breaking argument passing
* [25]9853: miscompilation of non-constant structure initializer
* [26]9797: C99-style struct initializers are miscompiled
* [27]9967: Some standard C function calls should not be replaced
when optimizing for size
* [28]10116: ce2: invalid merge of join_bb in the context of switch
statements
* [29]10171: wrong code for inlined function
* [30]10175: -Wunreachable-code doesn't work for single lines

C++ compiler and library:

* [31]8316: Confusing diagnostic for code that misuses conversion
operators
* [32]9169: filebuf output fails if codecvt<>::out returns noconv
* [33]9420: incomplete type incorrectly reported
* [34]9459: typeof in return type specification of template not
supported
* [35]9507: filebuf::open handles ios_base::ate incorrectly
* [36]9538: Out-of-bounds memory access in streambuf::sputbackc
* [37]9602: Total confusion about template/friend/virtual/abstract
* [38]9993: destructor not called for local object created within and
returned from infinite loop
* [39]10167: ieee_1003.1-2001 locale specialisations on a glibc-2.3.2
system

Java compiler and library:

* [40]9652: libgcj build fails on irix6.5.1[78]
* [41]10144: gas on solaris complains about bad .stabs lines for
java, native as unaffected

x86-specific (Intel/AMD):

* [42]8746: gcc miscompiles Linux kernel ppa driver on x86
* [43]9888: -mcpu=k6 -Os produces out of range loop instructions
* [44]9638: Cross-build for target i386-elf and i586-pc-linux-gnu
failed
* [45]9954: Cross-build for target i586-pc-linux-gnu (--with-newlib)
failed

SPARC-specific:

* [46]7784: [Sparc] ICE in extract_insn, in recog.c
* [47]7796: sparc extra failure with -m64 on execute/930921-1.c in
unroll.c
* [48]8281: ICE when compiling with -O2 -fPIC for Ultrasparc
* [49]8366: [Sparc] C testsuite failure with -m64 -fpic -O in
execute/loop-2d.c
* [50]8726: gcc -O2 miscompiles Samba 2.2.7 on 32-bit sparc
* [51]9414: Scheduling bug on Ultrasparc
* [52]10067: GCC-3.2.2 outputs invalid asm on sparc64

m68k-specific:

* [53]7248: broken "inclusive or" code
* [54]8343: m68k-elf/rtems ICE at instantiate_virtual_regs_1

PowerPC-specific:

* [55]9732: Wrong code with -O2 -fPIC
* [56]10073: ICE: powerpc cannot split insn

Alpha-specific:

* [57]7702: optimization problem on a DEC alpha under OSF1
* [58]9671: gcc.3.2.2 does not build on a HP Tru64 Unix v5.1B system

HP-specific:

* [59]8694: <string> breaks <ctype.h> on HP-UX 10.20 (DUP: 9275)
* [60]9953: (ada) gcc 3.2.x can't build 3.3-branch ada on HP-UX 10
(missing symbol)
* [61]10271: Floating point args don't get reloaded across function
calls with -O2

MIPS specific:

* [62]6362: mips-irix6 gcc-3.1 C testsuite failure with -mips4 in
compile/920501-4.c

CRIS specific:

* [63]10377: gcc-3.2.2 creates bad assembler code for cris

Miscellaneous and minor bugs:

* [64]6955: collect2 says "core dumped" when there is no core
__________________________________________________________________

[65]GCC 3.2.2

Beginning with 3.2.2, GCC's Makefile suite supports redirection of make
install by means of the DESTDIR variable. Parts of the GCC tree have
featured that support long before, but now it is available even from
the top level.

Other than that, GCC 3.2.2 is a bug fix release only; there are no new
features that were not present in GCC 3.2.1.

Bug Fixes

On the following i386-based systems GCC 3.2.1 broke the C ABI wrt.
functions returning structures: Cygwin, FreeBSD (GCC 3.2.1 as shipped
with FreeBSD 5.0 does not have this problem), Interix, a.out-based
GNU/Linux and NetBSD, OpenBSD, and Darwin. GCC 3.2.2 reverts this ABI
change, and thus restores ABI-compatibility with previous releases
(except GCC 3.2.1) on these platforms.

This section lists the problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 3.2.2 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here) and some of the titles have been changed to
make them more clear.

Internal Compiler Errors (multi-platform)

* [66]5919: (c++) ICE when passing variable array to template
function
* [67]7129: (c++) ICE with min/max assignment operators (<?= and >?=)
* [68]7507: ICE with -O2 when address of called function is a
complicated expression
* [69]7622: ICE with nested inline functions if function's address is
taken
* [70]7681: (fortran) ICE in compensate_edge, in reg-stack.c (also PR
[71]9258)
* [72]8031: (c++) ICE in code comparing typeids and casting from
virtual base
* [73]8275: ICE in simplify_subreg
* [74]8332: (c++) builtin strlen/template interaction causes ICE
* [75]8372: (c++) ICE on explicit call of destructor
* [76]8439: (c, not c++) empty struct causes ICE
* [77]8442: (c++) ICE with nested template classes
* [78]8518: ICE when compiling mplayer ("extern inline" issue)
* [79]8615: (c++) ICE with out-of-range character constant template
argument
* [80]8663: (c++) ICE in cp_expr_size, at cp-lang.c:307
* [81]8799: (c++) ICE: error reporting routines re-entered
* [82]9328: (c++) ICE with typeof(X) for overloaded X
* [83]9465: (preprocessor) cpp -traditional ICE on null bytes

C++ (compiler and library) bugs

* [84]47: scoping in nested classes is broken
* [85]6745: problems with iostream rdbuf() member function
* [86]8214: conversion from const char* const to char* sometimes
accepted illegally
* [87]8493: builtin strlen and overload resolution (same bug as
[88]8332)
* [89]8503: strange behaviour of function types
* [90]8727: compiler confused by inheritance from an anonymous struct
* [91]7445: poor performance of std::locale::classic() in
multi-threaded applications
* [92]8230: mishandling of overflow in vector<T>::resize
* [93]8399: sync_with_stdio(false) breaks unformatted input
* [94]8662: illegal access of private member of unnamed class is
accepted
* [95]8707: "make distclean" fails in libstdc++-v3 directory
* [96]8708: __USE_MALLOC doesn't work
* [97]8790: Use of non-thread-safe strtok in src/localename.cc
* [98]8887: Bug in date formats with --enable-clocale=generic
* [99]9076: Call Frame Instructions are not handled correctly during
unwind operation
* [100]9151: std::setprecision limited to 16 digits when outputting a
double to a stream
* [101]9168: codecvt<char, char, mbstate_t> overwrites output buffers
* [102]9269: libstdc++ headers: explicit specialization of function
must precede its first use
* [103]9322: return value of basic_streambuf<>::getloc affected by
locale::global
* [104]9433: segfault in runtime support for dynamic_cast

C and optimizer bugs

* [105]8032: GCC incorrectly initializes static structs that have
flexible arrays
* [106]8639: simple arithmetic expression broken
* [107]8794: optimization improperly eliminates certain expressions
* [108]8832: traditional "asm volatile" code is illegally optimized
* [109]8988: loop optimizer bug: with -O2, code is generated that
segfaults (found on i386, bug present for all platforms)
* [110]9492: structure copy clobbers subsequent stores to structure

Objective-C bugs

* [111]9267: Objective-C parser won't build with newer bison versions
(e.g. 1.875)

Ada bugs

* [112]8344: Ada build problem due to conflict between gcc/final.o,
gcc/ada/final.o

Preprocessor bugs

* [113]8524: _Pragma within macros is improperly expanded
* [114]8880: __WCHAR_TYPE__ macro incorrectly set to "long int" with
-fshort-wchar

ARM-specific

* [115]9090: arm ICE with >= -O2; regression from gcc-2.95

x86-specific (Intel/AMD)

* [116]8588: ICE in extract_insn, at recog.c:NNNN (shift instruction)
* [117]8599: loop unroll bug with -march=k6-3
* [118]9506: ABI breakage in structure return (affects BSD and
Cygwin, but not GNU/Linux)

FreeBSD 5.0 specific

* [119]9484: GCC 3.2.1 Bootstrap failure on FreeBSD 5.0

RTEMS-specific

* [120]9292: hppa1.1-rtems configurery problems
* [121]9293: [m68k-elf/rtems] config/m68k/t-crtstuff bug
* [122]9295: [mips-rtems] config/mips/rtems.h init/fini issue
* [123]9296: gthr-rtems regression
* [124]9316: powerpc-rtems: extending multilibs

HP-PA specific

* [125]9493: ICE with -O2 when building a simple function

Documentation

* [126]7341: hyperlink to gcov in GCC documentation doesn't work
* [127]8947: Please add a warning about "-malign-double" in docs
* [128]7448, [129]8882: typo cleanups
__________________________________________________________________

[130]GCC 3.2.1

3.2.1 adds a new warning, -Wabi. This option warns when GNU C++
generates code that is known not to be binary-compatible with the
vendor-neutral ia32/ia64 ABI. Please consult the GCC manual, included
in the distribution, for details.

This release also removes an old GCC extension, "naming types", and the
documentation now directs users to use a different GCC extension,
__typeof__, instead. The feature had evidently been broken for a while.

Otherwise, 3.2.1 is a bug fix release only; other than bug fixes and
the new warning there are no new features that were not present in GCC
3.2.

In addition, the previous fix for [131]PR 7445 (poor performance of
std::locale::classic() in multi-threaded applications) was reverted
("unfixed"), because the "fix" was not thread-safe.

Bug Fixes

This section lists the problem reports (PRs) from GCC's bug tracking
system that are known to be fixed in the 3.2.1 release. This list might
not be complete (that is, it is possible that some PRs that have been
fixed are not listed here). As you can see, the number of bug fixes is
quite large, so it is strongly recommended that users of earlier GCC
3.x releases upgrade to GCC 3.2.1.

Internal Compiler Errors (multi-platform)

* [132]2521: (c++) ICE in build_ptrmemfunc, in cp/typeck.c
* [133]5661: (c++) ICE instantiating template on array of unknown
size (bad code)
* [134]6419: (c++) ICE in make_decl_rtl for "longest" attribute on
64-bit platforms
* [135]6994: (c++) ICE in find_function_data
* [136]7150: preprocessor: GCC -dM -E gives an ICE
* [137]7160: ICE when optimizing branches without a return value
* [138]7228: (c++) ICE when using member template and template
function
* [139]7266: (c++) ICE with -pedantic on missing typename
* [140]7353: ICE from use of "Naming Types" extension, see above
* [141]7411: ICE in instantiate_virtual_regs_1, in function.c
* [142]7478: (c++) ICE on static_cast inside template
* [143]7526: preprocessor core dump when _Pragma implies #pragma
dependency
* [144]7721: (c++) ICE on simple (but incorrect) template ([145]7803
is a duplicate)
* [146]7754: (c++) ICE on union with template parameter
* [147]7788: (c++) redeclaring a definition as an incomplete class
causes ICE
* [148]8031: (c++) ICE in comptypes, in cp/typeck.c
* [149]8055: preprocessor dies with SIG11 when building FreeBSD
kernel
* [150]8067: (c++) ICE due to mishandling of __FUNCTION__ and related
variables
* [151]8134: (c++) ICE in force_store_init_value on legal code
* [152]8149: (c++) ICE on incomplete type
* [153]8160: (c++) ICE in build_modify_expr, in cp/typeck.c: array
initialization

C++ (compiler and library) bugs

* [154]5607: No pointer adjustment in covariant return types
* [155]6579: Infinite loop with statement expressions in member
initialization
* [156]6803: Default copy constructor bug in GCC 3.1
* [157]7176: g++ confused by friend and static member with same name
* [158]7188: Segfault with template class and recursive (incorrect)
initializer list
* [159]7306: Regression: GCC 3.x fails to compile code with virtual
inheritance if a method has a variable number of arguments
* [160]7461: ctype<char>::classic_table() returns offset array on
Cygwin
* [161]7524: f(const float arg[3]) fails
* [162]7584: Erroneous ambiguous base error on using declaration
* [163]7676: Member template overloading problem
* [164]7679: infinite loop when a right parenthesis is missing
* [165]7811: default locale not taken from environment
* [166]7961: compare( char *) implemented incorrectly in
basic_string<>
* [167]8071: basic_ostream::operator<<(streambuf*) loops forever if
streambuf::underflow() leaves gptr() NULL (dups: [168]8127,
[169]6745)
* [170]8096: deque::at() throws std::range_error instead of
std::out_of_range
* [171]8127: cout << cin.rdbuf() infinite loop
* [172]8218: Excessively large memory consumed for classes with large
array members
* [173]8287: GCC 3.2: Destructor called for non-constructed local
object
* [174]8347: empty vector range used in string construction causes
core dump
* [175]8348: fail() flag is set in istringstream when eof() flag is
set
* [176]8391: regression: infinite loop in cp/decl2.c(finish_file)

C and optimizer bugs

* [177]6627: -fno-align-functions doesn't seem to disable function
alignment
* [178]6631: life_analysis misoptimizes code to initialize fields of
a structure
* [179]7102: unsigned char division results in floating exception
* [180]7120: Run once loop should *always* be unrolled
(pessimization)
* [181]7209: Bug involving array referencing and ?: operator
* [182]7515: invalid inlining of global function with -O3
* [183]7814: incorrect scheduling for glibc-2.2.92 strcpy test
* [184]8467: bug in sibling call optimization

Preprocessor bugs

* [185]4890: incorrect line markers from the traditional preprocessor
* [186]7357: -M option omits system headers files (making it the same
as -MM)
* [187]7358: Changes to Sun's make Dependencies
* [188]7602: C++ header files found in CPLUS_INCLUDE_PATH treated as
C headers
* [189]7862: Interrupting GCC -MD removes .d file but not .o
* [190]8190: Failed compilation deletes -MD dependency file
* [191]8524: _Pragma within macro is improperly expanded

x86 specific (Intel/AMD)

* [192]5351: (i686-only) function pass-by-value structure copy
corrupts stack ([193]7591 is a duplicate)
* [194]6845, [195]7034, [196]7124, [197]7174: ICE's with
-march=pentium3/pentium2/athlon (these are all the same underlying
bug, in MMX register use)
* [198]7134, [199]7375, [200]7390: ICE with -march=athlon (maybe same
as above?)
* [201]6890: xmmintrin.h, _MM_TRANSPOSE4_PS is broken
* [202]6981: wrong code in 64-bit manipulation on x86
* [203]7242: GCC -mcpu=pentium[23] doesn't define __tune_pentiumpro__
macro
* [204]7396: ix86: cmpgt_ss, cmpge_ss, cmpngt_ss, and cmpnge_ss SSE
intrinsics are broken
* [205]7630: GCC 3.2 breaks on Mozilla 1.0's JS sources with
-march=pentium4
* [206]7693: Typo in i386 mmintrin.h header
* [207]7723: ICE - Pentium3 sse - GCC 3.2
* [208]7951: ICE on -march=pentium4 -O2 -mfpmath=sse
* [209]8146: (i686 only) gcc 3.2 miscompiles gcc 2.95.3

PowerPC specific

* [210]5967: GCC bug when profiling nested functions on powerpc
* [211]6984: wrong code generated with -O2, -O3, -Os for do-while
loop on PowerPC
* [212]7114: PowerPC: ICE building strcoll.op from glibc-2.2.5
* [213]7130: miscompiled code for GCC-3.1 on
powerpc-unknown-linux-gnu with -funroll-all-loops
* [214]7133: PowerPC ICE: unrecognizable insn
* [215]7380: ICE in extract_insn, at recog.c:2148
* [216]8252: ICE on Altivec code with optimization turned on
* [217]8451: Altivec ICE in GCC 3.2

HP/PA specific

* [218]7250: __ashrdi3 returns wrong value on 32 bit hppa

SPARC specific

* [219]6668: when using --disable-multilib, libgcc_s.so is installed
in the wrong place on sparc-solaris
* [220]7151: ICE when compiling for UltraSPARC
* [221]7335: SPARC: ICE in verify_wide_reg (flow.c:557) with long
double and -O1
* [222]7842: [REGRESSION] SPARC code gen bug

ARM specific

* [223]7856: [arm] invalid offset in constant pool reference
* [224]7967: optimization produces wrong code (ARM)

Alpha specific

* [225]7374: __builtin_fabsl broken on alpha

IBM s390 specific

* [226]7370: ICE in fixup_var_refs_1 on s390x
* [227]7409: loop optimization bug on s390x-linux-gnu
* [228]8232: s390x: ICE when using bcmp with int length argument

SCO specific

* [229]7623: SCO OpenServer build fails with machmode.def: undefined
symbol: BITS_PER_UNIT

m68k/Coldfire specific

* [230]8314: crtbegin, crtend need to be multilib'ed for this
platform

Documentation

* [231]761: Document some undocumented options
* [232]5610: Fix documentation about invoking SSE instructions
(-mfpmath=sse)
* [233]7484: List -Wmissing-declarations as C-only option
* [234]7531: -mcmodel not documented for x86-64
* [235]8120: Update documentation of bad use of ##
__________________________________________________________________

[236]GCC 3.2

3.2 is a small bug fix release, but there is a change to the
application binary interface (ABI), hence the change to the second part
of the version number.

The main purpose of the 3.2 release is to correct a couple of problems
in the C++ ABI, with the intention of providing a stable interface
going forward. Accordingly, 3.2 is only a small change to 3.1.1.

Bug Fixes

C++

* [237]7320: g++ 3.2 relocation problem
* [238]7470: vtable: virtual function pointers not in declaration
order

libstdc++

* [239]6410: Trouble with non-ASCII monetary symbols and wchar_t
* [240]6503, [241]6642, [242]7186: Problems with comparing or
subtracting various types of const and non-const iterators
* [243]7216: ambiguity with basic_iostream::traits_type
* [244]7220: problem with basic_istream::ignore(0,delimiter)
* [245]7222: locale::operator==() doesn't work on std::locale("")
* [246]7286: placement operator delete issue
* [247]7442: cxxabi.h does not match the C++ ABI
* [248]7445: poor performance of std::locale::classic() in
multi-threaded applications

x86-64 specific

* [249]7291: off-by-one in generated inline bzero code for x86-64

For questions related to the use of GCC, please consult these web
pages and the [250]GCC manuals. If that fails, the
[251][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [252][email protected]. All of [253]our lists have public
archives.

Copyright (C) [254]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [255]maintained by the GCC team. Last modified
2025-04-08.

References

1. https://gcc.gnu.org/gcc-3.2/changes.html#3.2.3
2. https://gcc.gnu.org/gcc-3.1/changes.html
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80. https://gcc.gnu.org/PR8663
81. https://gcc.gnu.org/PR8799
82. https://gcc.gnu.org/PR9328
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84. https://gcc.gnu.org/PR47
85. https://gcc.gnu.org/PR6745
86. https://gcc.gnu.org/PR8214
87. https://gcc.gnu.org/PR8493
88. https://gcc.gnu.org/PR8332
89. https://gcc.gnu.org/PR8503
90. https://gcc.gnu.org/PR8727
91. https://gcc.gnu.org/PR7445
92. https://gcc.gnu.org/PR8230
93. https://gcc.gnu.org/PR8399
94. https://gcc.gnu.org/PR8662
95. https://gcc.gnu.org/PR8707
96. https://gcc.gnu.org/PR8708
97. https://gcc.gnu.org/PR8790
98. https://gcc.gnu.org/PR8887
99. https://gcc.gnu.org/PR9076
100. https://gcc.gnu.org/PR9151
101. https://gcc.gnu.org/PR9168
102. https://gcc.gnu.org/PR9269
103. https://gcc.gnu.org/PR9322
104. https://gcc.gnu.org/PR9433
105. https://gcc.gnu.org/PR8032
106. https://gcc.gnu.org/PR8639
107. https://gcc.gnu.org/PR8794
108. https://gcc.gnu.org/PR8832
109. https://gcc.gnu.org/PR8988
110. https://gcc.gnu.org/PR9492
111. https://gcc.gnu.org/PR9267
112. https://gcc.gnu.org/PR8344
113. https://gcc.gnu.org/PR8524
114. https://gcc.gnu.org/PR8880
115. https://gcc.gnu.org/PR9090
116. https://gcc.gnu.org/PR8588
117. https://gcc.gnu.org/PR8599
118. https://gcc.gnu.org/PR9506
119. https://gcc.gnu.org/PR9484
120. https://gcc.gnu.org/PR9292
121. https://gcc.gnu.org/PR9293
122. https://gcc.gnu.org/PR9295
123. https://gcc.gnu.org/PR9296
124. https://gcc.gnu.org/PR9316
125. https://gcc.gnu.org/PR9493
126. https://gcc.gnu.org/PR7341
127. https://gcc.gnu.org/PR8947
128. https://gcc.gnu.org/PR7448
129. https://gcc.gnu.org/PR8882
130. https://gcc.gnu.org/gcc-3.2/changes.html#GCC3.2.1
131. https://gcc.gnu.org/PR7445
132. https://gcc.gnu.org/PR2521
133. https://gcc.gnu.org/PR5661
134. https://gcc.gnu.org/PR6419
135. https://gcc.gnu.org/PR6994
136. https://gcc.gnu.org/PR7150
137. https://gcc.gnu.org/PR7160
138. https://gcc.gnu.org/PR7228
139. https://gcc.gnu.org/PR7266
140. https://gcc.gnu.org/PR7353
141. https://gcc.gnu.org/PR7411
142. https://gcc.gnu.org/PR7478
143. https://gcc.gnu.org/PR7526
144. https://gcc.gnu.org/PR7721
145. https://gcc.gnu.org/PR7803
146. https://gcc.gnu.org/PR7754
147. https://gcc.gnu.org/PR7788
148. https://gcc.gnu.org/PR8031
149. https://gcc.gnu.org/PR8055
150. https://gcc.gnu.org/PR8067
151. https://gcc.gnu.org/PR8134
152. https://gcc.gnu.org/PR8149
153. https://gcc.gnu.org/PR8160
154. https://gcc.gnu.org/PR5607
155. https://gcc.gnu.org/PR6579
156. https://gcc.gnu.org/PR6803
157. https://gcc.gnu.org/PR7176
158. https://gcc.gnu.org/PR7188
159. https://gcc.gnu.org/PR7306
160. https://gcc.gnu.org/PR7461
161. https://gcc.gnu.org/PR7524
162. https://gcc.gnu.org/PR7584
163. https://gcc.gnu.org/PR7676
164. https://gcc.gnu.org/PR7679
165. https://gcc.gnu.org/PR7811
166. https://gcc.gnu.org/PR7961
167. https://gcc.gnu.org/PR8071
168. https://gcc.gnu.org/PR8127
169. https://gcc.gnu.org/PR6745
170. https://gcc.gnu.org/PR8096
171. https://gcc.gnu.org/PR8127
172. https://gcc.gnu.org/PR8218
173. https://gcc.gnu.org/PR8287
174. https://gcc.gnu.org/PR8347
175. https://gcc.gnu.org/PR8348
176. https://gcc.gnu.org/PR8391
177. https://gcc.gnu.org/PR6627
178. https://gcc.gnu.org/PR6631
179. https://gcc.gnu.org/PR7102
180. https://gcc.gnu.org/PR7120
181. https://gcc.gnu.org/PR7209
182. https://gcc.gnu.org/PR7515
183. https://gcc.gnu.org/PR7814
184. https://gcc.gnu.org/PR8467
185. https://gcc.gnu.org/PR4890
186. https://gcc.gnu.org/PR7357
187. https://gcc.gnu.org/PR7358
188. https://gcc.gnu.org/PR7602
189. https://gcc.gnu.org/PR7862
190. https://gcc.gnu.org/PR8190
191. https://gcc.gnu.org/PR8524
192. https://gcc.gnu.org/PR5351
193. https://gcc.gnu.org/PR7591
194. https://gcc.gnu.org/PR6845
195. https://gcc.gnu.org/PR7034
196. https://gcc.gnu.org/PR7124
197. https://gcc.gnu.org/PR7174
198. https://gcc.gnu.org/PR7134
199. https://gcc.gnu.org/PR7375
200. https://gcc.gnu.org/PR7390
201. https://gcc.gnu.org/PR6890
202. https://gcc.gnu.org/PR6981
203. https://gcc.gnu.org/PR7242
204. https://gcc.gnu.org/PR7396
205. https://gcc.gnu.org/PR7630
206. https://gcc.gnu.org/PR7693
207. https://gcc.gnu.org/PR7723
208. https://gcc.gnu.org/PR7951
209. https://gcc.gnu.org/PR8146
210. https://gcc.gnu.org/PR5967
211. https://gcc.gnu.org/PR6984
212. https://gcc.gnu.org/PR7114
213. https://gcc.gnu.org/PR7130
214. https://gcc.gnu.org/PR7133
215. https://gcc.gnu.org/PR7380
216. https://gcc.gnu.org/PR8252
217. https://gcc.gnu.org/PR8451
218. https://gcc.gnu.org/PR7250
219. https://gcc.gnu.org/PR6668
220. https://gcc.gnu.org/PR7151
221. https://gcc.gnu.org/PR7335
222. https://gcc.gnu.org/PR7842
223. https://gcc.gnu.org/PR7856
224. https://gcc.gnu.org/PR7967
225. https://gcc.gnu.org/PR7374
226. https://gcc.gnu.org/PR7370
227. https://gcc.gnu.org/PR7409
228. https://gcc.gnu.org/PR8232
229. https://gcc.gnu.org/PR7623
230. https://gcc.gnu.org/PR8314
231. https://gcc.gnu.org/PR761
232. https://gcc.gnu.org/PR5610
233. https://gcc.gnu.org/PR7484
234. https://gcc.gnu.org/PR7531
235. https://gcc.gnu.org/PR8120
236. https://gcc.gnu.org/gcc-3.2/changes.html#GCC3.2
237. https://gcc.gnu.org/PR7320
238. https://gcc.gnu.org/PR7470
239. https://gcc.gnu.org/PR6410
240. https://gcc.gnu.org/PR6503
241. https://gcc.gnu.org/PR6642
242. https://gcc.gnu.org/PR7186
243. https://gcc.gnu.org/PR7216
244. https://gcc.gnu.org/PR7220
245. https://gcc.gnu.org/PR7222
246. https://gcc.gnu.org/PR7286
247. https://gcc.gnu.org/PR7442
248. https://gcc.gnu.org/PR7445
249. https://gcc.gnu.org/PR7291
250. https://gcc.gnu.org/onlinedocs/
251. mailto:[email protected]
252. mailto:[email protected]
253. https://gcc.gnu.org/lists.html
254. https://www.fsf.org/
255. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-3.1/index.html

GCC 3.1

(This release series is no longer supported.)

July 27, 2002

The GNU project and the GCC developers are pleased to announce the
release of GCC 3.1.1.

The links below still apply to GCC 3.1.1.

May 15, 2002

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 3.1.

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

A list of [2]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed [3]new features, improvements, bug fixes, and other changes
as well as test results to GCC. This [4]amazing group of volunteers is
what makes GCC successful.

For additional information about GCC please refer to the [5]GCC project
web site or contact the [6]GCC development mailing list.

To obtain GCC please use [7]our mirror sites, or our CVS server.
__________________________________________________________________

For questions related to the use of GCC, please consult these web
pages and the [8]GCC manuals. If that fails, the
[9][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [10][email protected]. All of [11]our lists have public
archives.

Copyright (C) [12]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [13]maintained by the GCC team. Last modified
2024-07-04.

References

1. https://www.gnu.org/
2. https://gcc.gnu.org/gcc-3.1/buildstat.html
3. https://gcc.gnu.org/gcc-3.1/changes.html
4. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
5. https://gcc.gnu.org/index.html
6. mailto:[email protected]
7. https://gcc.gnu.org/mirrors.html
8. https://gcc.gnu.org/onlinedocs/
9. mailto:[email protected]
10. mailto:[email protected]
11. https://gcc.gnu.org/lists.html
12. https://www.fsf.org/
13. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-3.1/changes.html

GCC 3.1 Release Series
Changes, New Features, and Fixes

Additional changes in GCC 3.1.1

* A bug related to how structures and unions are returned has been
fixed for powerpc-*-netbsd*.
* An important bug in the implementation of -fprefetch-loop-arrays
has been fixed. Previously the optimization prefetched random
blocks of memory for most targets except for i386.
* The Java compiler now compiles Java programs much faster and also
works with parallel make.
* Nested functions have been fixed for mips*-*-netbsd*.
* Some missing floating point support routines have beed added for
mips*-*-netbsd*.
* This [1]message gives additional information about the bugs fixed
in this release.

Caveats

* The -traditional C compiler option has been deprecated and will be
removed in GCC 3.3. (It remains possible to preprocess non-C code
with the traditional preprocessor.)
* The default debugging format for most ELF platforms (including
GNU/Linux and FreeBSD; notable exception is Solaris) has changed
from stabs to DWARF2. This requires GDB 5.1.1 or later.

General Optimizer Improvements

* Jan Hubicka, SuSE Labs, together with Richard Henderson, Red Hat,
and Andreas Jaeger, SuSE Labs, has contributed [2]infrastructure
for profile driven optimizations.
Options -fprofile-arcs and -fbranch-probabilities can now be used
to improve speed of the generated code by profiling the actual
program behaviour on typical runs. In the absence of profile info
the compiler attempts to guess the profile statically.
* [3]SPEC2000 and SPEC95 benchmark suites are now used daily to
monitor performance of the generated code.
According to the SPECInt2000 results on an AMD Athlon CPU, the code
generated by GCC 3.1 is 6% faster on the average (8.2% faster with
profile feedback) compared to GCC 3.0. The code produced by GCC 3.0
is about 2.1% faster compared to 2.95.3. Tests were done using the
-O2 -march=athlon command-line options.
* Alexandre Oliva, of Red Hat, has generalized the tree inlining
infrastructure developed by CodeSourcery, LLC for the C++ front
end, so that it is now used in the C front end too. Inlining
functions as trees exposes them earlier to the compiler, giving it
more opportunities for optimization.
* Support for data prefetching instructions has been added to the GCC
back end and several targets. A new __builtin_prefetch intrinsic is
available to explicitly insert prefetch instructions and
experimental support for loop array prefetching has been added (see
-fprefetch-loop-array documentation).
* Support for emitting debugging information for macros has been
added for DWARF2. It is activated using -g3.

New Languages and Language specific improvements

C/C++

* A few more [4]ISO C99 features.
* The preprocessor is 10-50% faster than the preprocessor in GCC 3.0.
* The preprocessor's symbol table has been merged with the symbol
table of the C, C++ and Objective-C front ends.
* The preprocessor consumes less memory than the preprocessor in GCC
3.0, often significantly so. On normal input files, it typically
consumes less memory than pre-3.0 cccp-based GCC, too.

C++

* -fhonor-std and -fno-honor-std have been removed. -fno-honor-std
was a workaround to allow std compliant code to work with the
non-std compliant libstdc++-v2. libstdc++-v3 is std compliant.
* The C++ ABI has been fixed so that void (A::*)() const is mangled
as "M1AKFvvE", rather than "MK1AFvvE" as before. This change only
affects pointer to cv-qualified member function types.
* The C++ ABI has been changed to correctly handle this code:
struct A {
void operator delete[] (void *, size_t);
};

struct B : public A {
};

new B[10];

The amount of storage allocated for the array will be greater than
it was in 3.0, in order to store the number of elements in the
array, so that the correct size can be passed to operator delete[]
when the array is deleted. Previously, the value passed to operator
delete[] was unpredictable.
This change will only affect code that declares a two-argument
operator delete[] with a second parameter of type size_t in a base
class, and does not override that definition in a derived class.
* The C++ ABI has been changed so that:
struct A {
void operator delete[] (void *, size_t);
void operator delete[] (void *);
};

does not cause unnecessary storage to be allocated when an array of
A objects is allocated.
This change will only affect code that declares both of these forms
of operator delete[], and declared the two-argument form before the
one-argument form.
* The C++ ABI has been changed so that when a parameter is passed by
value, any cleanup for that parameter is performed in the caller,
as specified by the ia64 C++ ABI, rather than the called function
as before. As a result, classes with a non-trivial destructor but a
trivial copy constructor will be passed and returned by invisible
reference, rather than by bitwise copy as before.
* G++ now supports the "named return value optimization": for code
like
A f () {
A a;
...
return a;
}

G++ will allocate a in the return value slot, so that the return
becomes a no-op. For this to work, all return statements in the
function must return the same variable.
* Improvements to the C++ library are listed in [5]the libstdc++-v3
FAQ.

Objective-C

* Annoying linker warnings (due to incorrect code being generated)
have been fixed.
* If a class method cannot be found, the compiler no longer issues a
warning if a corresponding instance method exists in the root
class.
* Forward @protocol declarations have been fixed.
* Loading of categories has been fixed in certain situations (GNU run
time only).
* The class lookup in the run-time library has been rewritten so that
class method dispatch is more than twice as fast as it used to be
(GNU run time only).

Java

* libgcj now includes RMI, java.lang.ref.*, javax.naming, and
javax.transaction.
* Property files and other system resources can be compiled into
executables which use libgcj using the new gcj --resource feature.
* libgcj has been ported to more platforms. In particular there is
now a mostly-functional mingw32 (Windows) target port.
* JNI and CNI invocation interfaces were implemented, so gcj-compiled
Java code can now be called from a C/C++ application.
* gcj can now use builtin functions for certain known methods, for
instance Math.cos.
* gcj can now automatically remove redundant array-store checks in
some common cases.
* The --no-store-checks optimization option was added. This can be
used to omit runtime store checks for code which is known not to
throw ArrayStoreException
* The following third party interface standards were added to libgcj:
org.w3c.dom and org.xml.sax.
* java.security has been merged with GNU Classpath. The new package
is now JDK 1.2 compliant, and much more complete.
* A bytecode verifier was added to the libgcj interpreter.
* java.lang.Character was rewritten to comply with the Unicode 3.0
standard, and improve performance.
* Partial support for many more locales was added to libgcj.
* Socket timeouts have been implemented.
* libgcj has been merged into a single shared library. There are no
longer separate shared libraries for the garbage collector and
zlib.
* Several performance improvements were made to gcj and libgcj:
+ Hash synchronization (thin locks)
+ A special allocation path for finalizer-free objects
+ Thread-local allocation
+ Parallel GC, and other GC tweaks

Fortran

Fortran improvements are listed in [6]the Fortran documentation.

Ada

[7]AdaCore, has contributed its GNAT Ada 95 front end and associated
tools. The GNAT compiler fully implements the Ada language as defined
by the ISO/IEC 8652 standard.

Please note that the integration of the Ada front end is still work in
progress.

New Targets and Target Specific Improvements

* Hans-Peter Nilsson has contributed a port to MMIX, the CPU
architecture used in new editions of Donald E. Knuth's The Art of
Computer Programming.
* Axis Communications has contributed its port to the CRIS CPU
architecture, used in the ETRAX system-on-a-chip series.
* Alexandre Oliva, of Red Hat, has contributed a port to the SuperH
SH5 64-bit RISC microprocessor architecture, extending the existing
SH port.
* UltraSPARC is fully supported in 64-bit mode. The option -m64
enables it.
* For compatibility with the Sun compiler #pragma redefine_extname
has been implemented on Solaris.
* The x86 back end has had some noticeable work done to it.
+ SuSE Labs developers Jan Hubicka, Bo Thorsen and Andreas
Jaeger have contributed a port to the AMD x86-64 architecture.
For more information on x86-64 see http://www.x86-64.org.
+ The compiler now supports MMX, 3DNow!, SSE, and SSE2
instructions. Options -mmmx, -m3dnow, -msse, and -msse2 will
enable the respective instruction sets. Intel C++ compatible
MMX/3DNow!/SSE intrinsics are implemented. SSE2 intrinsics
will be added in next major release.
+ Following those improvements, targets for Pentium MMX, K6-2,
K6-3, Pentium III, Pentium 4, and Athlon 4 Mobile/XP/MP were
added. Refer to the documentation on -march= and -mcpu=
options for details.
+ For those targets that support it, -mfpmath=sse will cause the
compiler to generate SSE/SSE2 instructions for floating point
math instead of x87 instructions. Usually, this will lead to
quicker code -- especially on the Pentium 4. Note that only
scalar floating point instructions are used and GCC does not
exploit SIMD features yet.
+ Prefetch support has been added to the Pentium III, Pentium 4,
K6-2, K6-3, and Athlon series.
+ Code generated for floating point to integer conversions has
been improved leading to better performance of many 3D
applications.
* The PowerPC back end has added 64-bit PowerPC GNU/Linux support.
* C++ support for AIX has been improved.
* Aldy Hernandez, of Red Hat, Inc, has contributed extensions to the
PowerPC port supporting the AltiVec programming model (SIMD). The
support, though presently useful, is experimental and is expected
to stabilize for 3.2. The support is written to conform to
Motorola's AltiVec specs. See -maltivec.

[8]Obsolete Systems

Support for a number of older systems has been declared obsolete in GCC
3.1. Unless there is activity to revive them, the next release of GCC
will have their sources permanently removed.

All configurations of the following processor architectures have been
declared obsolete:
* MIL-STD-1750A, 1750a-*-*
* AMD A29k, a29k-*-*
* Convex, c*-convex-*
* Clipper, clipper-*-*
* Elxsi, elxsi-*-*
* Intel i860, i860-*-*
* Sun picoJava, pj-*-* and pjl-*-*
* Western Electric 32000, we32k-*-*

Most configurations of the following processor architectures have been
declared obsolete, but we are preserving a few systems which may have
active developers. It is unlikely that the remaining systems will
survive much longer unless we see definite signs of port activity.
* Motorola 88000 except
+ Generic a.out, m88k-*-aout*
+ Generic SVR4, m88k-*-sysv4
+ OpenBSD, m88k-*-openbsd*
* NS32k except
+ NetBSD, ns32k-*-netbsd*
+ OpenBSD, ns32k-*-openbsd*.
* ROMP except
+ OpenBSD, romp-*-openbsd*.

Finally, only some configurations of these processor architectures are
being obsoleted.
* Alpha:
+ OSF/1, alpha*-*-osf[123]*. (Digital Unix and Tru64 Unix, aka
alpha*-*-osf[45], are still supported.)
* ARM:
+ RISCiX, arm-*-riscix*.
* i386:
+ 386BSD, i?86-*-bsd*
+ Chorus, i?86-*-chorusos*
+ DG/UX, i?86-*-dgux*
+ FreeBSD 1.x, i?86-*-freebsd1.*
+ IBM AIX, i?86-*-aix*
+ ISC UNIX, i?86-*-isc*
+ GNU/Linux with pre-BFD linker, i?86-*-linux*oldld*
+ NEXTstep, i?86-next-*
+ OSF UNIX, i?86-*-osf1* and i?86-*-osfrose*
+ RTEMS/coff, i?86-*-rtemscoff*
+ RTEMS/go32, i?86-go32-rtems*
+ Sequent/BSD, i?86-sequent-bsd*
+ Sequent/ptx before version 3, i?86-sequent-ptx[12]* and
i?86-sequent-sysv3*
+ SunOS, i?86-*-sunos*
* Motorola 68000:
+ Altos, m68[k0]*-altos-*
+ Apollo, m68[k0]*-apollo-*
+ Apple A/UX, m68[k0]*-apple-*
+ Bull, m68[k0]*-bull-*
+ Convergent, m68[k0]*-convergent-*
+ Generic SVR3, m68[k0]*-*-sysv3*
+ ISI, m68[k0]*-isi-*
+ LynxOS, m68[k0]*-*-lynxos*
+ NEXT, m68[k0]*-next-*
+ RTEMS/coff, m68[k0]*-*-rtemscoff*
+ Sony, m68[k0]*-sony-*
* MIPS:
+ DEC Ultrix, mips-*-ultrix* and mips-dec-*
+ Generic BSD, mips-*-bsd*
+ Generic System V, mips-*-sysv*
+ IRIX before version 5, mips-sgi-irix[1234]*
+ RiscOS, mips-*-riscos*
+ Sony, mips-sony-*
+ Tandem, mips-tandem-*
* SPARC:
+ RTEMS/a.out, sparc-*-rtemsaout*.

Documentation improvements

* The old manual ("Using and Porting the GNU Compiler Collection")
has been replaced by a users manual ("Using the GNU Compiler
Collection") and a separate internals reference manual ("GNU
Compiler Collection Internals").
* More complete and much improved documentation about GCC's internal
representation used by the C and C++ front ends.
* Many cleanups and improvements in general.

For questions related to the use of GCC, please consult these web
pages and the [9]GCC manuals. If that fails, the
[10][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [11][email protected]. All of [12]our lists have public
archives.

Copyright (C) [13]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [14]maintained by the GCC team. Last modified
2025-06-05.

References

1. https://gcc.gnu.org/ml/gcc/2002-07/msg01208.html
2. https://gcc.gnu.org/news/profiledriven.html
3. https://gcc.gnu.org/benchmarks/
4. https://gcc.gnu.org/projects/c-status.html
5. https://gcc.gnu.org/onlinedocs/libstdc++/faq.html
6. https://gcc.gnu.org/onlinedocs/gcc-3.1.1/g77/News.html
7. https://www.adacore.com/
8. https://gcc.gnu.org/gcc-3.1/changes.html#obsolete_systems
9. https://gcc.gnu.org/onlinedocs/
10. mailto:[email protected]
11. mailto:[email protected]
12. https://gcc.gnu.org/lists.html
13. https://www.fsf.org/
14. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-3.0/index.html

GCC 3.0.4

(This release series is no longer supported.)

February 20, 2002

The [1]GNU project and the GCC developers are pleased to announce the
release of GCC 3.0.4, which is a bug-fix release for the GCC 3.0
series.

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

GCC 3.0.x has several new optimizations, new targets, new languages and
many other new features, relative to GCC 2.95.x. See the [2]new
features page for a more complete list.

A list of [3]successful builds is updated as new information becomes
available.

The GCC developers would like to thank the numerous people that have
contributed new features, test results, bug fixes, etc to GCC. This
[4]amazing group of volunteers is what makes GCC successful.

And finally, we can't in good conscience fail to mention some
[5]caveats to using GCC 3.0.x.

For additional information about GCC please refer to the [6]GCC project
web site or contact the [7]GCC development mailing list.

To obtain GCC please use [8]our mirror sites, or our CVS server.
__________________________________________________________________

Previous 3.0.x Releases

December 20, 2001: GCC 3.0.3 has been released.
October 25, 2001: GCC 3.0.2 has been released.
August 20, 2001: GCC 3.0.1 has been released.
June 18, 2001: GCC 3.0 has been released.

For questions related to the use of GCC, please consult these web
pages and the [9]GCC manuals. If that fails, the
[10][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [11][email protected]. All of [12]our lists have public
archives.

Copyright (C) [13]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [14]maintained by the GCC team. Last modified
2024-07-04.

References

1. https://www.gnu.org/
2. https://gcc.gnu.org/gcc-3.0/features.html
3. https://gcc.gnu.org/gcc-3.0/buildstat.html
4. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
5. https://gcc.gnu.org/gcc-3.0/caveats.html
6. https://gcc.gnu.org/index.html
7. mailto:[email protected]
8. https://gcc.gnu.org/mirrors.html
9. https://gcc.gnu.org/onlinedocs/
10. mailto:[email protected]
11. mailto:[email protected]
12. https://gcc.gnu.org/lists.html
13. https://www.fsf.org/
14. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-3.0/features.html

GCC 3.0 New Features

Additional changes in GCC 3.0.4

* GCC 3.0 now supports newer versions of the [1]NetBSD operating
system, which use the ELF object file format, on x86 processors.
* Correct debugging information is generated from functions that have
lines from multiple files (e.g. yacc output).
* A fix for whitespace handling in the -traditional preprocessor,
which can affect Fortran.
* Fixes to the exception handling runtime.
* More fixes for bad code generation in C++.
* A fix for shared library generation under AIX 4.3.
* Documentation updates.
* Port of GCC to Tensilica's Xtensa processor contributed.
* A fix for compiling the PPC Linux kernel (FAT fs wouldn't link).

Additional changes in GCC 3.0.3

* A fix to correct an accidental change to the PowerPC ABI.
* Fixes for bad code generation on a variety of architectures.
* Improvements to the debugging information generated for C++
classes.
* Fixes for bad code generation in C++.
* A fix to avoid crashes in the C++ demangler.
* A fix to the C++ standard library to avoid buffer overflows.
* Miscellaneous improvements for a variety of architectures.

Additional changes in GCC 3.0.2

* Fixes for bad code generation during loop unrolling.
* Fixes for bad code generation by the sibling call optimization.
* Minor improvements to x86 code generation.
* Implementation of function descriptors in C++ vtables for IA64.
* Numerous minor bug-fixes.

Additional changes in GCC 3.0.1

* C++ fixes for incorrect code-generation.
* Improved cross-compiling support for the C++ standard library.
* Fixes for some embedded targets that worked in GCC 2.95.3, but not
in GCC 3.0.
* Fixes for various exception-handling bugs.
* A port to the S/390 architecture.

General Optimizer Improvements

* [2]Basic block reordering pass.
* New if-conversion pass with support for conditional (predicated)
execution.
* New tail call and sibling call elimination optimizations.
* New register renaming pass.
* New (experimental) [3]static single assignment (SSA) representation
support.
* New dead-code elimination pass implemented using the SSA
representation.
* [4]Global null pointer test elimination.
* [5]Global code hoisting/unification.
* More builtins and optimizations for stdio.h, string.h and old BSD
functions, as well as for ISO C99 functions.
* New builtin __builtin_expect for giving hints to the branch
predictor.

New Languages and Language specific improvements

* The GNU Compiler for the Java(TM) language (GCJ) is now integrated
and supported, including the run-time library containing most
common non-GUI Java classes, a bytecode interpreter, and the Boehm
conservative garbage collector. Many bugs have been fixed. GCJ can
compile Java source or Java bytecodes to either native code or Java
class files, and supports native methods written in either the
standard JNI or the more efficient and convenient CNI.
* Here is a [6]partial list of C++ improvements, both new features
and those no longer supported.
* New C++ ABI. On the IA-64 platform GCC is capable of
inter-operating with other IA-64 compilers.
* The new ABI also significantly reduces the size of symbol and debug
information.
* New C++ support library and many C++ bug fixes, vastly improving
our conformance to the ISO C++ standard.
* New [7]inliner for C++.
* Rewritten C preprocessor, integrated into the C, C++ and Objective
C compilers, with very many improvements including ISO C99 support
and [8]improvements to dependency generation.
* Support for more [9]ISO C99 features.
* Many improvements to support for checking calls to format functions
such as printf and scanf, including support for ISO C99 format
features, extensions from the Single Unix Specification and GNU
libc 2.2, checking of strfmon formats and features to assist in
auditing for format string security bugs.
* New warnings for C code that may have undefined semantics because
of violations of sequence point rules in the C standard (such as a
= a++;, a[n] = b[n++]; and a[i++] = i;), included in -Wall.
* Additional warning option -Wfloat-equal.
* Improvements to -Wtraditional.
* Fortran improvements are listed in [10]the Fortran documentation.

New Targets and Target Specific Improvements

* New x86 back end, generating much improved code.
* Support for a generic i386-elf target contributed.
* New option to emit x86 assembly code using Intel style syntax
(-mintel-syntax).
* HPUX 11 support contributed.
* Improved PowerPC code generation, including scheduled prologue and
epilogue.
* Port of GCC to Intel's IA-64 processor contributed.
* Port of GCC to Motorola's MCore 210 and 340 contributed.
* New unified back-end for Arm, Thumb and StrongArm contributed.
* Port of GCC to Intel's XScale processor contributed.
* Port of GCC to Atmel's AVR microcontrollers contributed.
* Port of GCC to Mitsubishi's D30V processor contributed.
* Port of GCC to Matsushita's AM33 processor (a member of the MN10300
processor family) contributed.
* Port of GCC to Fujitsu's FR30 processor contributed.
* Port of GCC to Motorola's 68HC11 and 68HC12 processors contributed.
* Port of GCC to Sun's picoJava processor core contributed.

Documentation improvements

* Substantially rewritten and improved C preprocessor manual.
* Many improvements to other documentation.
* Manpages for gcc, cpp and gcov are now generated automatically from
the master Texinfo manual, eliminating the problem of manpages
being out of date. (The generated manpages are only extracts from
the full manual, which is provided in Texinfo form, from which
info, HTML, other formats and a printed manual can be generated.)
* Generated info files are included in the release tarballs alongside
their Texinfo sources, avoiding problems on some platforms with
building makeinfo as part of the GCC distribution.

Other significant improvements

* Garbage collection used internally by the compiler for most memory
allocation instead of obstacks.
* Lengauer and Tarjan algorithm used for computing dominators in the
CFG. This algorithm can be significantly faster and more space
efficient than our older algorithm.
* gccbug script provided to assist in submitting bug reports to our
bug tracking system. (Bug reports previously submitted directly to
our mailing lists, for which you received no bug tracking number,
should be submitted again using gccbug if you can reproduce the
problem with GCC 3.0.)
* The internal libgcc library is [11]built as a shared library on
systems that support it.
* Extensive testsuite included with GCC, with many new tests. In
addition to tests for GCC bugs that have been fixed, many tests
have been added for language features, compiler warnings and
builtin functions.
* Additional language-independent warning options -Wpacked, -Wpadded,
-Wunreachable-code and -Wdisabled-optimization.
* Target-independent options -falign-functions, -falign-loops and
-falign-jumps.

Plus a great many bug fixes and almost all the [12]features found in
GCC 2.95.

For questions related to the use of GCC, please consult these web
pages and the [13]GCC manuals. If that fails, the
[14][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [15][email protected]. All of [16]our lists have public
archives.

Copyright (C) [17]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [18]maintained by the GCC team. Last modified
2025-06-05.

References

1. http://www.netbsd.org/
2. https://gcc.gnu.org/news/reorder.html
3. https://gcc.gnu.org/news/ssa.html
4. https://gcc.gnu.org/news/null.html
5. https://gcc.gnu.org/news/unify.html
6. https://gcc.gnu.org/gcc-3.0/c++features.html
7. https://gcc.gnu.org/news/inlining.html
8. https://gcc.gnu.org/news/dependencies.html
9. https://gcc.gnu.org/projects/c-status.html
10. https://gcc.gnu.org/onlinedocs/gcc-3.4.6/g77/News.html
11. https://gcc.gnu.org/gcc-3.0/libgcc.html
12. https://gcc.gnu.org/gcc-2.95/features.html
13. https://gcc.gnu.org/onlinedocs/
14. mailto:[email protected]
15. mailto:[email protected]
16. https://gcc.gnu.org/lists.html
17. https://www.fsf.org/
18. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-3.0/caveats.html

GCC 3.0 Caveats

* -fstrict-aliasing is now part of -O2 and higher optimization
levels. This allows the compiler to assume the strictest aliasing
rules applicable to the language being compiled. For C and C++,
this activates optimizations based on the type of expressions. This
optimization may thus break old, non-compliant code.
* Enumerations are now properly promoted to int in function
parameters and function returns. Normally this change is not
visible, but when using -fshort-enums this is an ABI change.
* The undocumented extension that allowed C programs to have a label
at the end of a compound statement has been deprecated and may be
removed in a future version. Programs that now generate a warning
about this may be fixed by adding a null statement (a single
semicolon) after the label.
* The poorly documented extension that allowed string constants in C,
C++ and Objective C to contain unescaped newlines has been
deprecated and may be removed in a future version. Programs using
this extension may be fixed in several ways: the bare newline may
be replaced by \n, or preceded by \n\, or string concatenation may
be used with the bare newline preceded by \n" and " placed at the
start of the next line.
* The Chill compiler is not included in GCC 3.0, because of the lack
of a volunteer to convert it to use garbage collection.
* Certain non-standard iostream methods from earlier versions of
libstdc++ are not included in libstdc++ v3, i.e. filebuf::attach,
ostream::form, and istream::gets.
* The new C++ ABI is not yet fully supported by current (as of
2001-07-01) releases and development versions of GDB, or any
earlier versions. There is a problem setting breakpoints by line
number, and other related issues that have been fixed in GCC 3.0
but not yet handled in GDB:
[1]https://gcc.gnu.org/ml/gcc-bugs/2001-06/msg00421.html

For questions related to the use of GCC, please consult these web
pages and the [2]GCC manuals. If that fails, the
[3][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [4][email protected]. All of [5]our lists have public archives.

Copyright (C) [6]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [7]maintained by the GCC team. Last modified
2022-10-26.

References

1. https://gcc.gnu.org/ml/gcc-bugs/2001-06/msg00421.html
2. https://gcc.gnu.org/onlinedocs/
3. mailto:[email protected]
4. mailto:[email protected]
5. https://gcc.gnu.org/lists.html
6. https://www.fsf.org/
7. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-2.95/index.html

GCC 2.95

(This release series is no longer supported.)

March 16, 2001: The GNU project and the GCC developers are pleased to
announce the release of GCC version 2.95.3.

Release History

GCC 2.95.3
March 16, 2001

GCC 2.95.2
October 27, 1999

GCC 2.95.1
August 19, 1999

GCC 2.95
July 31, 1999. This is the first release of GCC since the April
1999 GCC/EGCS reunification and includes nearly a year's worth
of new development and bugfixes.

References and Acknowledgements

GCC used to stand for the GNU C Compiler, but since the compiler
supports several other languages aside from C, it now stands for the
GNU Compiler Collection.

The whole suite has been extensively [1]regression tested and
[2]package tested. It should be reliable and suitable for widespread
use.

The compiler has several new optimizations, new targets, new languages
and other new features. See the [3]new features page for a more
complete list of new features found in the GCC 2.95 releases.

The sources include installation instructions in both HTML and
plaintext forms in the install directory in the distribution. However,
the most up to date installation instructions and [4]build/test status
are on the web pages. We will update those pages as new information
becomes available.

The GCC developers would like to thank the numerous people that have
contributed new features, test results, bugfixes, etc to GCC. This
[5]amazing group of volunteers is what makes GCC successful.

And finally, we can't in good conscience fail to mention some
[6]caveats to using GCC 2.95.

Download GCC 2.95 from one of our many [7]mirror sites.

For additional information about GCC please see the [8]GCC project web
server or contact the [9]GCC development mailing list.

For questions related to the use of GCC, please consult these web
pages and the [10]GCC manuals. If that fails, the
[11][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [12][email protected]. All of [13]our lists have public
archives.

Copyright (C) [14]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [15]maintained by the GCC team. Last modified
2022-10-26.

References

1. https://gcc.gnu.org/gcc-2.95/regress.html
2. https://gcc.gnu.org/gcc-2.95/othertest.html
3. https://gcc.gnu.org/gcc-2.95/features.html
4. https://gcc.gnu.org/gcc-2.95/buildstat.html
5. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
6. https://gcc.gnu.org/gcc-2.95/caveats.html
7. https://gcc.gnu.org/mirrors.html
8. https://gcc.gnu.org/index.html
9. mailto:[email protected]
10. https://gcc.gnu.org/onlinedocs/
11. mailto:[email protected]
12. mailto:[email protected]
13. https://gcc.gnu.org/lists.html
14. https://www.fsf.org/
15. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-2.95/features.html

GCC 2.95 New Features

* General Optimizer Improvements:
+ [1]Localized register spilling to improve speed and code
density especially on small register class machines.
+ [2]Global CSE using lazy code motion algorithms.
+ [3]Improved global constant/copy propagation.
+ [4]Improved control flow graph analysis and manipulation.
+ [5]Local dead store elimination.
+ [6]Memory Load hoisting/store sinking in loops.
+ [7]Type based alias analysis is enabled by default. Note this
feature will expose bugs in the Linux kernel. Please refer to
the FAQ (as shipped with GCC 2.95) for additional information
on this issue.
+ Major revamp of GIV detection, combination and simplification
to improve loop performance.
+ Major improvements to register allocation and reloading.
* New Languages and Language specific improvements
+ [8]Many C++ improvements.
+ [9]Many Fortran improvements.
+ [10]Java front-end has been integrated. A [11]runtime library
is available separately.
+ [12]ISO C99 support
+ [13]Chill front-end and runtime has been integrated.
+ Boehm garbage collector support in libobjc.
+ More support for various pragmas which appear in vendor
include files
* New Targets and Target Specific Improvements
+ [14]SPARC back end rewrite.
+ -mschedule=8000 will optimize code for PA8000 class
processors; -mpa-risc-2-0 will generate code for PA2.0
processors
+ Various micro-optimizations for the ia32 port. K6
optimizations
+ Compiler will attempt to align doubles in the stack on the
ia32 port
+ Alpha EV6 support
+ PowerPC 750
+ RS6000/PowerPC: -mcpu=401 was added as an alias for -mcpu=403.
-mcpu=e603e was added to do -mcpu=603e and -msoft-float.
+ c3x, c4x
+ HyperSPARC
+ SparcLite86x
+ sh4
+ Support for new systems (OpenBSD, FreeBSD, UWIN, Interix,
arm-linux)
+ vxWorks targets include support for vxWorks threads
+ StrongARM 110 and ARM9 support added. ARM Scheduling
parameters rewritten.
+ Various changes to the MIPS port to avoid assembler macros,
which in turn improves performance
+ Various performance improvements to the i960 port.
+ Major rewrite of ns32k port
* Other significant improvements
+ [15]Ability to dump cfg information and display it using vcg.
+ The new faster scheme for fixing vendor header files is
enabled by default.
+ Experimental internationalization support.
+ multibyte character support
+ Some compile-time speedups for pathological problems
+ Better support for complex types
* Plus the usual mountain of bugfixes
* Core compiler is based on the gcc2 development tree from Sept 30,
1998, so we have all of the [16]features found in GCC 2.8.

Additional Changes in GCC 2.95.1

* Generic bugfixes and improvements
+ Various documentation fixes related to the GCC/EGCS merger.
+ Fix memory management bug which could lead to spurious aborts,
core dumps or random parsing errors in the compiler.
+ Fix a couple bugs in the dwarf1 and dwarf2 debug record
support.
+ Fix infinite loop in the CSE optimizer.
+ Avoid undefined behavior in compiler FP emulation code
+ Fix install problem when prefix is overridden on the make
install command.
+ Fix problem with unwanted installation of assert.h on some
systems.
+ Fix problem with finding the wrong assembler in a single tree
build.
+ Avoid increasing the known alignment of a register that is
already known to be a pointer.
* Platform specific bugfixes and improvements
+ Codegen bugfix for prologue/epilogue for cpu32 target.
+ Fix long long code generation bug for the Coldfire target.
+ Fix various aborts in the SH compiler.
+ Fix bugs in libgcc support library for the SH.
+ Fix alpha ev6 code generation bug.
+ Fix problems with EXIT_SUCCESS/EXIT_FAILURE redefinitions on
AIX platforms.
+ Fix -fpic code generation bug for rs6000/ppc svr4 targets.
+ Fix varargs/stdarg code generation bug for rs6000/ppc svr4
targets.
+ Fix weak symbol handling for rs6000/ppc svr4 targets.
+ Fix various problems with 64bit code generation for the
rs6000/ppc port.
+ Fix codegen bug which caused tetex to be mis-compiled on the
x86.
+ Fix compiler abort in new cfg code exposed by x86 port.
+ Fix out of range array reference in code convert flat
registers to the x87 stacked FP register file.
+ Fix minor vxworks configuration bug.
+ Fix return type of bsearch for SunOS 4.x.
* Language & Runtime specific fixes.
+ The G++ signature extension has been deprecated. It will be
removed in the next major release of G++. Use of signatures
will result in a warning from the compiler.
+ Several bugs relating to templates and namespaces were fixed.
+ A bug that caused crashes when combining templates with -g on
DWARF1 platforms was fixed.
+ Pointers-to-members, virtual functions, and multiple
inheritance should now work together correctly.
+ Some code-generation bugs relating to function try blocks were
fixed.
+ G++ is a little bit more lenient with certain archaic
constructs than in GCC 2.95.
+ Fix to prevent shared library version #s from bring truncated
to 1 digit
+ Fix missing std:: in the libstdc++ library.
+ Fix stream locking problems in libio.
+ Fix problem in java compiler driver.

Additional Changes in GCC 2.95.2

The -fstrict-aliasing is not enabled by default for GCC 2.95.2. While
the optimizations performed by -fstrict-aliasing are valid according to
the C and C++ standards, the optimization have caused some problems,
particularly with old non-conforming code.

The GCC developers are experimenting with ways to warn users about code
which violates the C/C++ standards, but those warnings are not ready
for widespread use at this time. Rather than wait for those warnings
the GCC developers have chosen to disable -fstrict-aliasing by default
for the GCC 2.95.2 release.

We strongly encourage developers to find and fix code which violates
the C/C++ standards as -fstrict-aliasing may be enabled by default in
future releases. Use the option -fstrict-aliasing to re-enable these
optimizations.
* Generic bugfixes and improvements
+ Fix incorrectly optimized memory reference in global common
subexpression elimination (GCSE) optimization pass.
+ Fix code generation bug in regmove.c in which it could
incorrectly change a "const" value.
+ Fix bug in optimization of conditionals involving volatile
memory references.
+ Avoid over-allocation of stack space for some procedures.
+ Fixed bug in the compiler which caused incorrect optimization
of an obscure series of bit manipulations, shifts and
arithmetic.
+ Fixed register allocator bug which caused teTeX to be
mis-compiled on SPARC targets.
+ Avoid incorrect optimization of degenerate case statements for
certain targets such as the ARM.
+ Fix out of range memory reference in the jump optimizer.
+ Avoid dereferencing null pointer in fix-header.
+ Fix test for GCC specific features so that it is possible to
bootstrap with gcc-2.6.2 and older versions of GCC.
+ Fix typo in scheduler which could potentially cause out of
range memory accesses.
+ Avoid incorrect loop reversal which caused incorrect code for
certain loops on PowerPC targets.
+ Avoid incorrect optimization of switch statements on certain
targets (for example the ARM).
* Platform specific bugfixes and improvements
+ Work around bug in Sun V5.0 compilers which caused bootstrap
comparison failures on SPARC targets.
+ Fix SPARC back end bug which caused aborts in final.c.
+ Fix sparc-hal-solaris2* configuration fragments.
+ Fix bug in sparc block profiling.
+ Fix obscure code generation bug for the PARISC targets.
+ Define __STDC_EXT__ for HPUX configurations.
+ Various POWERPC64 code generation bugfixes.
+ Fix abort for PPC targets using ELF (ex GNU/Linux).
+ Fix collect2 problems for AIX targets.
+ Correct handling of .file directive for PPC targets.
+ Fix bug in fix_trunc x86 patterns.
+ Fix x86 port to correctly pop the FP stack for functions that
return structures in memory.
+ Fix minor bug in strlen x86 pattern.
+ Use stabs debugging instead of dwarf1 for x86-solaris targets.
+ Fix template repository code to handle leading underscore in
mangled names.
+ Fix weak/weak alias support for OpenBSD.
+ GNU/Linux for the ARM has C++ compatible include files.
* Language & Runtime specific fixes.
+ Fix handling of constructor attribute in the C front-end which
caused problems building the Chill runtime library on some
targets.
+ Fix minor problem merging type qualifiers in the C front-end.
+ Fix aliasing bug for pointers and references (C/C++).
+ Fix incorrect "non-constant initializer bug" when -traditional
or -fwritable-strings is enabled.
+ Fix build error for Chill front-end on SunOS.
+ Do not complain about duplicate instantiations when using
-frepo (C++).
+ Fix array bounds handling in C++ front-end which caused
problems with dwarf debugging information in some
circumstances.
+ Fix minor namespace problem.
+ Fix problem linking java programs.

Additional Changes in GCC 2.95.3

* Generic bugfixes and improvements
+ Fix numerous problems that caused incorrect optimization in
the register reloading code.
+ Fix numerous problems that caused incorrect optimization in
the loop optimizer.
+ Fix aborts in the functions build_insn_chain and scan_loops
under some circumstances.
+ Fix an alias analysis bug.
+ Fix an infinite compilation bug in the combiner.
+ A few problems with complex number support have been fixed.
+ It is no longer possible for gcc to act as a fork bomb when
installed incorrectly.
+ The -fpack-struct option should be recognized now.
+ Fixed a bug that caused incorrect code to be generated due to
a lost stack adjustment.
* Platform specific bugfixes and improvements
+ Support building ARM toolchains hosted on Windows.
+ Fix attribute calculations in ARM toolchains.
+ arm-linux support has been improved.
+ Fix a PIC failure on sparc targets.
+ On ix86 targets, the regparm attribute should now work
reliably.
+ Several updates for the h8300 port.
+ Fix problem building libio with glibc 2.2.

For questions related to the use of GCC, please consult these web
pages and the [17]GCC manuals. If that fails, the
[18][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [19][email protected]. All of [20]our lists have public
archives.

Copyright (C) [21]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [22]maintained by the GCC team. Last modified
2025-06-05.

References

1. https://gcc.gnu.org/news/spill.html
2. https://gcc.gnu.org/news/lcm.html
3. https://gcc.gnu.org/news/cprop.html
4. https://gcc.gnu.org/news/cfg.html
5. https://gcc.gnu.org/news/dse.html
6. https://gcc.gnu.org/news/hoist.html
7. https://gcc.gnu.org/news/alias.html
8. https://gcc.gnu.org/gcc-2.95/c++features.html
9. https://gcc.gnu.org/onlinedocs/gcc-3.4.6/g77/News.html
10. https://gcc.gnu.org/news/gcj-announce.txt
11. https://gcc.gnu.org/news/javaannounce.html
12. https://gcc.gnu.org/projects/c-status.html
13. https://gcc.gnu.org/news/chill.html
14. https://gcc.gnu.org/news/sparc.html
15. https://gcc.gnu.org/news/egcs-vcg.html
16. https://gcc.gnu.org/egcs-1.0/features-2.8.html
17. https://gcc.gnu.org/onlinedocs/
18. mailto:[email protected]
19. mailto:[email protected]
20. https://gcc.gnu.org/lists.html
21. https://www.fsf.org/
22. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/gcc-2.95/caveats.html

GCC 2.95 Caveats

* GCC 2.95 will issue an error for invalid asm statements that had
been silently accepted by earlier versions of the compiler. This is
particularly noticeable when compiling older versions of the Linux
kernel (2.0.xx). Please refer to the FAQ (as shipped with GCC 2.95)
for more information on this issue.
* GCC 2.95 implements type based alias analysis to disambiguate
memory references. Some programs, particularly the Linux kernel
violate ANSI/ISO aliasing rules and therefore may not operate
correctly when compiled with GCC 2.95. Please refer to the FAQ (as
shipped with GCC 2.95) for more information on this issue.
* GCC 2.95 has a known bug in its handling of complex variables for
64bit targets. Instead of silently generating incorrect code, GCC
2.95 will issue a fatal error for situations it can not handle.
This primarily affects the Fortran community as Fortran makes more
use of complex variables than C or C++.
* GCC 2.95 has an integrated libstdc++, but does not have an
integrated libg++. Furthermore old libg++ releases will not work
with GCC 2.95. You can retrieve a recent copy of libg++ from the
[1]GCC ftp server.
Note most C++ programs only need libstdc++.
* Exception handling may not work with shared libraries, particularly
on alphas, hppas, rs6000/powerpc and mips based platforms.
Exception handling is known to work on x86 GNU/Linux platforms with
shared libraries.
* In general, GCC 2.95 is more rigorous about rejecting invalid C++
code or deprecated C++ constructs than G++ 2.7, G++ 2.8, EGCS 1.0,
or EGCS 1.1. As a result it may be necessary to fix C++ code before
it will compile with GCC 2.95.
* G++ is also converting toward the ISO C++ standard; as a result
code which was previously valid (and thus accepted by other
compilers and older versions of g++) may no longer be accepted. The
flag -fpermissive may allow some non-conforming code to compile
with GCC 2.95.
* GCC 2.95 compiled C++ code is not binary compatible with EGCS
1.1.x, EGCS 1.0.x or GCC 2.8.x.
* GCC 2.95 does not have changes from the GCC 2.8 tree that were made
between Sept 30, 1998 and April 30, 1999 (the official end of the
GCC 2.8 project). Future GCC releases will include all the changes
from the defunct GCC 2.8 sources.

For questions related to the use of GCC, please consult these web
pages and the [2]GCC manuals. If that fails, the
[3][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [4][email protected]. All of [5]our lists have public archives.

Copyright (C) [6]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [7]maintained by the GCC team. Last modified
2022-10-26.

References

1. ftp://gcc.gnu.org/pub/gcc/infrastructure/libg++-2.8.1.3.tar.gz
2. https://gcc.gnu.org/onlinedocs/
3. mailto:[email protected]
4. mailto:[email protected]
5. https://gcc.gnu.org/lists.html
6. https://www.fsf.org/
7. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/egcs-1.1/index.html

EGCS 1.1

September 3, 1998: We are pleased to announce the release of EGCS 1.1.
December 1, 1998: We are pleased to announce the release of EGCS 1.1.1.
March 15, 1999: We are pleased to announce the release of EGCS 1.1.2.

EGCS is a free software project to further the development of the GNU
compilers using an open development environment.

EGCS 1.1 is a major new release of the EGCS compiler system. It has
been [1]extensively tested and is believed to be stable and suitable
for widespread use.

EGCS 1.1 is based on an June 6, 1998 snapshot of the GCC 2.8
development sources; it contains all of the new features found in GCC
2.8.1 as well as all new development from GCC up to June 6, 1998.

EGCS 1.1 also contains many improvements and features not found in GCC
or in older versions of EGCS:
* Global common subexpression elimination and global constant/copy
propagation (aka [2]gcse)
* Ongoing improvements to the [3]alias analysis support to allow for
better optimizations throughout the compiler.
* Vastly improved [4]C++ compiler and integrated C++ runtime
libraries.
* Fixes for the /tmp symlink race security problems.
* New targets including mips16, arm-thumb and 64-bit PowerPC.
* Improvements to GNU Fortran (g77) compiler and runtime library made
since g77 version 0.5.23.

See the [5]new features page for a more complete list of new features
found in EGCS 1.1 releases.

EGCS 1.1.1 is a minor update to fix several serious problems in EGCS
1.1:
* General improvements and fixes
+ Avoid some stack overflows when compiling large functions.
+ Avoid incorrect loop invariant code motions.
+ Fix some core dumps on Linux kernel code.
+ Bring back the imake -Di386 and friends fix from EGCS 1.0.2.
+ Fix code generation problem in gcse.
+ Various documentation related fixes.
* g++/libstdc++ improvements and fixes
+ MT safe EH fix for setjmp/longjmp based exception handling.
+ Fix a few bad interactions between optimization and exception
handling.
+ Fixes for demangling of template names starting with "__".
+ Fix a bug that would fail to run destructors in some cases
with -O2.
+ Fix 'new' of classes with virtual bases.
+ Fix crash building Qt on the Alpha.
+ Fix failure compiling WIFEXITED macro on GNU/Linux.
+ Fix some -frepo failures.
* g77 and libf2c improvements and fixes
+ Various documentation fixes.
+ Avoid compiler crash on RAND intrinsic.
+ Fix minor bugs in makefiles exposed by BSD make programs.
+ Define _XOPEN_SOURCE for libI77 build to avoid potential
problems on some 64-bit systems.
+ Fix problem with implicit endfile on rewind.
+ Fix spurious recursive I/O errors.
* platform specific improvements and fixes
+ Match all versions of UnixWare7.
+ Do not assume x86 SVR4 or UnixWare targets can handle stabs.
+ Fix PPC/RS6000 LEGITIMIZE_ADDRESS macro and bug in conversion
from unsigned ints to double precision floats.
+ Fix ARM ABI issue with NetBSD.
+ Fix a few arm code generation bugs.
+ Fixincludes will fix additional broken SCO OpenServer header
files.
+ Fix a m68k back end bug which caused invalid offsets in reg+d
addresses.
+ Fix problems with 64bit AIX 4.3 support.
+ Fix handling of long longs for varargs/stdarg functions on the
ppc.
+ Minor fixes to CPP predefines for Windows.
+ Fix code generation problems with gpr<->fpr copies for 64bit
ppc.
+ Fix a few coldfire code generation bugs.
+ Fix some more header file problems on SunOS 4.x.
+ Fix assert.h handling for RTEMS.
+ Fix Windows handling of TREE_SYMBOL_REFERENCED.
+ Fix x86 compiler abort in reg-stack pass.
+ Fix cygwin/windows problem with section attributes.
+ Fix Alpha code generation problem exposed by SMP Linux
kernels.
+ Fix typo in m68k 32->64bit integer conversion.
+ Make sure target libraries build with -fPIC for PPC & Alpha
targets.

EGCS 1.1.2 is a minor update to fix several serious problems in EGCS
1.1.1:
* General improvements and fixes
+ Fix bug in loop optimizer which caused the SPARC (and
potentially other) ports to segfault.
+ Fix infinite recursion in alias analysis and combiner code.
+ Fix bug in regclass preferencing.
+ Fix incorrect loop reversal which caused incorrect code to be
generated for several targets.
+ Fix return value for builtin memcpy.
+ Reduce compile time for certain loops which exposed quadratic
behavior in the loop optimizer.
+ Fix bug which caused volatile memory to be written multiple
times when only one write was needed/desired.
+ Fix compiler abort in caller-save.c
+ Fix combiner bug which caused incorrect code generation for
certain division by constant operations.
+ Fix incorrect code generation due to a bug in range check
optimizations.
+ Fix incorrect code generation due to mis-handling of clobbered
values in CSE.
+ Fix compiler abort/segfault due to incorrect register
splitting when unrolling loops.
+ Fix code generation involving autoincremented addresses with
ternary operators.
+ Work around bug in the scheduler which caused qt to be
mis-compiled on some platforms.
+ Fix code generation problems with -fshort-enums.
+ Tighten security for temporary files.
+ Improve compile time for codes which make heavy use of
overloaded functions.
+ Fix multiply defined constructor/destructor symbol problems.
+ Avoid setting bogus RPATH environment variable during
bootstrap.
+ Avoid GNU-make dependencies in the texinfo subdir.
+ Install CPP wrapper script in $(prefix)/bin if --enable-cpp.
--enable-cpp=<dirname> can be used to specify an additional
install directory for the cpp wrapper script.
+ Fix CSE bug which caused incorrect label-label refs to appear
on some platforms.
+ Avoid linking in EH routines from libgcc if they are not
needed.
+ Avoid obscure bug in aliasing code.
+ Fix bug in weak symbol handling.
* Platform-specific improvements and fixes
+ Fix detection of PPro/PII on Unixware 7.
+ Fix compiler segfault when building spec99 and other programs
for SPARC targets.
+ Fix code-generation bugs for integer and floating point
conditional move instructions on the PPro/PII.
+ Use fixincludes to fix byteorder problems on i?86-*-sysv.
+ Fix build failure for the arc port.
+ Fix floating point format configuration for i?86-gnu port.
+ Fix problems with hppa1.0-hp-hpux10.20 configuration when
threads are enabled.
+ Fix coldfire code generation bugs.
+ Fix "unrecognized insn" problems for Alpha and PPC ports.
+ Fix h8/300 code generation problem with floating point values
in memory.
+ Fix unrecognized insn problems for the m68k port.
+ Fix namespace-pollution problem for the x86 port.
+ Fix problems with old assembler on x86 NeXT systems.
+ Fix PIC code-generation problems for the SPARC port.
+ Fix minor bug with LONG_CALLS in PowerPC SVR4 support.
+ Fix minor ISO namespace violation in Alpha varargs/stdarg
support.
+ Fix incorrect "braf" instruction usage for the SH port.
+ Fix minor bug in va-sh which prevented its use with -ansi.
+ Fix problems recognizing and supporting FreeBSD.
+ Handle OpenBSD systems correctly.
+ Minor fixincludes fix for Digital UNIX 4.0B.
+ Fix problems with ctors/dtors in SCO shared libraries.
+ Abort instead of generating incorrect code for PPro/PII
floating point conditional moves.
+ Avoid multiply defined symbols on GNU/Linux systems using
libc-5.4.xx.
+ Fix abort in alpha compiler.
* Fortran-specific fixes
+ Fix the IDate intrinsic (VXT) (in libg2c) so the returned year
is in the documented, non-Y2K-compliant range of 0-99, instead
of being returned as 100 in the year 2000.
+ Fix the `Date_and_Time' intrinsic (in libg2c) to return the
milliseconds value properly in Values(8).
+ Fix the `LStat' intrinsic (in libg2c) to return device-ID
information properly in SArray(7).

Each release includes installation instructions in both HTML and
plaintext forms (see the INSTALL directory in the toplevel directory of
the distribution). However, we also keep the most up to date
installation instructions and [6]build/test status on our web page. We
will update those pages as new information becomes available.

The EGCS project would like to thank the numerous people that have
contributed new features, test results, bugfixes, etc. This [7]amazing
group of volunteers is what makes EGCS successful.

And finally, we can't in good conscience fail to mention some
[8]caveats to using EGCS 1.1.

Download EGCS from egcs.cygnus.com (USA California).

The EGCS 1.1 release is also available on many mirror sites.
[9]Goto mirror list to find a closer site.

For questions related to the use of GCC, please consult these web
pages and the [10]GCC manuals. If that fails, the
[11][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [12][email protected]. All of [13]our lists have public
archives.

Copyright (C) [14]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [15]maintained by the GCC team. Last modified
2024-05-18.

References

1. https://gcc.gnu.org/egcs-1.1/egcs-1.1-test.html
2. https://gcc.gnu.org/news/gcse.html
3. https://gcc.gnu.org/news/alias.html
4. https://gcc.gnu.org/egcs-1.1/c++features.html
5. https://gcc.gnu.org/egcs-1.1/features.html
6. https://gcc.gnu.org/egcs-1.1/buildstat.html
7. https://gcc.gnu.org/onlinedocs/gcc/Contributors.html
8. https://gcc.gnu.org/egcs-1.1/caveats.html
9. https://gcc.gnu.org/mirrors.html
10. https://gcc.gnu.org/onlinedocs/
11. mailto:[email protected]
12. mailto:[email protected]
13. https://gcc.gnu.org/lists.html
14. https://www.fsf.org/
15. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/egcs-1.1/features.html

EGCS 1.1 new features

* Integrated GNU Fortran (g77) compiler and runtime library with
improvements, based on g77 version 0.5.23.
* Vast improvements in the C++ compiler; so many they have [1]page of
their own!
* Compiler implements [2]global common subexpression elimination and
global copy/constant propagation.
* More major improvements in the [3]alias analysis code.
* More major improvements in the exception handling code to improve
performance, lower static overhead and provide the infrastructure
for future improvements.
* The infamous /tmp symlink race security problems have been fixed.
* The regmove optimization pass has been nearly completely rewritten
to improve performance of generated code.
* The compiler now recomputes register usage information before local
register allocation. By providing more accurate information to the
priority based allocator, we get better register allocation.
* The register reloading phase of the compiler optimizes spill code
much better than in previous releases.
* Some bad interactions between the register allocator and
instruction scheduler have been fixed, resulting in much better
code for certain programs. Additionally, we have tuned the
scheduler in various ways to improve performance of generated code
for some architectures.
* The compiler's branch shortening algorithms have been significantly
improved to work better on targets which align jump targets.
* The compiler now supports -Os to prefer optimizing for code space
over optimizing for code speed.
* The compiler will now totally eliminate library calls which compute
constant values. This primarily helps targets with no integer
div/mul support and targets without floating point support.
* The compiler now supports an extensive "--help" option.
* cpplib has been greatly improved and may be suitable for limited
use.
* Memory footprint for the compiler has been significantly reduced
for some pathological cases.
* The time to build EGCS has been improved for certain targets
(particularly the alpha and mips platforms).
* Many infrastructure improvements throughout the compiler, plus the
usual mountain of bugfixes and minor improvements.
* Target dependent improvements:
+ SPARC port now includes V8 plus and V9 support as well as
performance tuning for Ultra class machines. The SPARC port
now uses the Haifa scheduler.
+ Alpha port has been tuned for the EV6 processor and has an
optimized expansion of memcpy/bzero. The Alpha port now uses
the Haifa scheduler.
+ RS6000/PowerPC: support for the Power64 architecture and AIX
4.3. The RS6000/PowerPC port now uses the Haifa scheduler.
+ x86: Alignment of static store data and jump targets is per
Intel recommendations now. Various improvements throughout the
x86 port to improve performance on Pentium processors
(including improved epilogue sequences for Pentium chips and
back end improvements which should help register allocation on
all x86 variants. Conditional move support has been fixed and
enabled for PPro processors. The x86 port also better supports
64bit operations now. Unixware 7, a System V Release 5 target,
is now supported and SCO OpenServer targets can support GAS.
+ MIPS has improved multiply/multiply-add support and now
includes mips16 ISA support.
+ M68k has many micro-optimizations and Coldfire fixes.
* Core compiler is based on the GCC development tree from June 9,
1998, so we have all of the [4]features found in GCC 2.8.

For questions related to the use of GCC, please consult these web
pages and the [5]GCC manuals. If that fails, the
[6][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [7][email protected]. All of [8]our lists have public archives.

Copyright (C) [9]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [10]maintained by the GCC team. Last modified
2023-09-02.

References

1. https://gcc.gnu.org/egcs-1.1/c++features.html
2. https://gcc.gnu.org/news/gcse.html
3. https://gcc.gnu.org/news/alias.html
4. https://gcc.gnu.org/egcs-1.0/features-2.8.html
5. https://gcc.gnu.org/onlinedocs/
6. mailto:[email protected]
7. mailto:[email protected]
8. https://gcc.gnu.org/lists.html
9. https://www.fsf.org/
10. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/egcs-1.1/caveats.html

EGCS 1.1 Caveats

* EGCS has an integrated libstdc++, but does not have an integrated
libg++. Furthermore old libg++ releases will not work with EGCS; HJ
Lu has made a libg++-2.8.1.2 snapshot available which may work with
EGCS.
Note most C++ programs only need libstdc++.
* Exception handling may not work with shared libraries, particularly
on alphas, hppas, rs6000/powerpc and mips based platforms.
Exception handling is known to work on x86-linux platforms with
shared libraries.
* Some versions of the Linux kernel have bugs which prevent them from
being compiled or from running when compiled by EGCS. See the FAQ
(as shipped with EGCS 1.1) for additional information.
* In general, EGCS is more rigorous about rejecting invalid C++ code
or deprecated C++ constructs than g++-2.7, g++-2.8 or EGCS 1.0. As
a result it may be necessary to fix C++ code before it will compile
with EGCS.
* G++ is also converting toward the ISO C++ standard; as a result
code which was previously valid (and thus accepted by other
compilers and older versions of g++) may no longer be accepted.
* EGCS 1.1 compiled C++ code is not binary compatible with EGCS 1.0.x
or GCC 2.8.x due to changes necessary to support thread safe
exception handling.

For questions related to the use of GCC, please consult these web
pages and the [1]GCC manuals. If that fails, the
[2][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [3][email protected]. All of [4]our lists have public archives.

Copyright (C) [5]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [6]maintained by the GCC team. Last modified
2022-10-26.

References

1. https://gcc.gnu.org/onlinedocs/
2. mailto:[email protected]
3. mailto:[email protected]
4. https://gcc.gnu.org/lists.html
5. https://www.fsf.org/
6. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/egcs-1.0/index.html

EGCS 1.0

December 3, 1997: We are pleased to announce the release of EGCS 1.0.
January 6, 1998: We are pleased to announce the release of EGCS 1.0.1.
March 16, 1998: We are pleased to announce the release of EGCS 1.0.2.
May 15, 1998 We are pleased to announce the release of EGCS 1.0.3.

EGCS is a collaborative effort involving several groups of hackers
using an open development model to accelerate development and testing
of GNU compilers and runtime libraries.

An important goal of EGCS is to allow wide scale testing of
experimental features and optimizations; therefore, EGCS contains some
features and optimizations which are still under development. However,
EGCS has been carefully tested and should be comparable in quality to
most GCC releases.

EGCS 1.0 is based on an August 2, 1997 snapshot of the GCC 2.8
development sources; it contains nearly all of the new features found
in GCC 2.8.

EGCS 1.0 also contains many improvements and features not found in GCC
2.7 and even the GCC 2.8 series (which was released after the original
EGCS 1.0 release).
* Integrated C++ runtime libraries, including support for most major
GNU/Linux systems!
* The integrated libstdc++ library includes a verbatim copy of SGI's
STL release.
* Integrated GNU Fortran compiler.
* New instruction scheduler.
* New alias analysis code.

See the [1]new features page for a more complete list of new features.

EGCS 1.0.1 is a minor update to the EGCS 1.0 compiler to fix a few
critical bugs and add support for Red Hat 5.0 Linux. Changes since the
EGCS 1.0 release:
* Add support for Red Hat 5.0 Linux and better support for Linux
systems using glibc2.
Many programs failed to link when compiled with EGCS 1.0 on Red Hat
5.0 or on systems with newer versions of glibc2. EGCS 1.0.1 should
fix these problems.
* Compatibility with both EGCS 1.0 and GCC 2.8 libgcc exception
handling interfaces.
To avoid future compatibility problems, we strongly urge anyone who
is planning on distributing shared libraries that contain C++ code
to upgrade to EGCS 1.0.1 first.
Soon after EGCS 1.0 was released, the GCC developers made some
incompatible changes in libgcc's exception handling interfaces.
These changes were needed to solve problems on some platforms. This
means that GCC 2.8.0, when released, will not be seamlessly
compatible with shared libraries built by EGCS 1.0. The reason is
that the libgcc.a in GCC 2.8.0 will not contain a function needed
by the old interface.
The result of this is that there may be compatibility problems with
shared libraries built by EGCS 1.0 when used with GCC 2.8.0.
With EGCS 1.0.1, generated code uses the new (GCC 2.8.0) interface,
and libgcc.a has the support routines for both the old and the new
interfaces (so EGCS 1.0.1 and EGCS 1.0 code can be freely mixed,
and EGCS 1.0.1 and GCC 2.8.0 code can be freely mixed).
The maintainers of GCC 2.x have decided against including seamless
support for the old interface in 2.8.0, since it was never
"official", so to avoid future compatibility problems we recommend
against distributing any shared libraries built by EGCS 1.0 that
contain C++ code (upgrade to 1.0.1 and use that).
* Various bugfixes in the x86, hppa, mips, and rs6000/ppc back ends.
The x86 changes fix code generation errors exposed when building
glibc2 and the usual GNU/Linux dynamic linker (ld.so).
The hppa change fixes a compiler abort when configured for use with
RTEMS.
The MIPS changes fix problems with the definition of LONG_MAX on
newer systems, allow for command line selection of the target ABI,
and fix one code generation problem.
The rs6000/ppc change fixes some problems with passing structures
to varargs/stdarg functions.
* A few machine independent bugfixes, mostly to fix code generation
errors when building Linux kernels or glibc.
* Fix a few critical exception handling and template bugs in the C++
compiler.
* Fix Fortran namelist bug on alphas.
* Fix build problems on x86-solaris systems.

EGCS 1.0.2 is a minor update to the EGCS 1.0.1 compiler to fix several
serious problems in EGCS 1.0.1.
* General improvements and fixes
+ Memory consumption significantly reduced, especially for
templates and inline functions.
+ Fix various problems with glibc2.1.
+ Fix loop optimization bug exposed by rs6000/ppc port.
+ Fix to avoid potential code generation problems in jump.c.
+ Fix some undefined symbol problems in dwarf1 debug support.
* g++/libstdc++ improvements and fixes
+ libstdc++ in the EGCS release has been updated and should be
link compatible with libstdc++-2.8.
+ Various fixes in libio/libstdc++ to work better on GNU/Linux
systems.
+ Fix problems with duplicate symbols on systems that do not
support weak symbols.
+ Memory corruption bug and undefined symbols in bastring have
been fixed.
+ Various exception handling fixes.
+ Fix compiler abort for very long thunk names.
* g77 improvements and fixes
+ Fix compiler crash for omitted bound in Fortran CASE
statement.
+ Add missing entries to g77 lang-options.
+ Fix problem with -fpedantic in the g77 compiler.
+ Fix "backspace" problem with g77 on alphas.
+ Fix x86 back end problem with Fortran literals and -fpic.
+ Fix some of the problems with negative subscripts for g77 on
alphas.
+ Fixes for Fortran builds on cygwin32/mingw32.
* platform specific improvements and fixes
+ Fix long double problems on x86 (exposed by glibc).
+ x86 ports define i386 again to keep imake happy.
+ Fix exception handling support on NetBSD ports.
+ Several changes to collect2 to fix many problems with AIX.
+ Define __ELF__ for GNU/Linux on rs6000.
+ Fix -mcall-linux problem on GNU/Linux on rs6000.
+ Fix stdarg/vararg problem for GNU/Linux on rs6000.
+ Allow autoconf to select a proper install problem on AIX 3.1.
+ m68k port support includes -mcpu32 option as well as cpu32
multilibs.
+ Fix stdarg bug for irix6.
+ Allow EGCS to build on irix5 without the gnu assembler.
+ Fix problem with static linking on sco5.
+ Fix bootstrap on sco5 with native compiler.
+ Fix for abort building newlib on H8 target.
+ Fix fixincludes handling of math.h on SunOS.
+ Minor fix for Motorola 3300 m68k systems.

EGCS 1.0.3 is a minor update to the EGCS 1.0.2 compiler to fix a few
problems reported by Red Hat for builds of Red Hat 5.1.
* Generic bugfixes:
+ Fix a typo in the libio library which resulted in incorrect
behavior of istream::get.
+ Fix the Fortran negative array index problem.
+ Fix a major problem with the ObjC runtime thread support
exposed by glibc2.
+ Reduce memory consumption of the Haifa scheduler.
* Target specific bugfixes:
+ Fix one x86 floating point code generation bug exposed by
glibc2 builds.
+ Fix one x86 internal compiler error exposed by glibc2 builds.
+ Fix profiling bugs on the Alpha.
+ Fix ImageMagick & emacs 20.2 build problems on the Alpha.
+ Fix rs6000/ppc bug when converting values from integer types
to floating point types.

The EGCS 1.0 releases include installation instructions in both HTML
and plaintext forms (see the INSTALL directory in the toplevel
directory of the distribution). However, we also keep the most up to
date installation instructions and [2]build/test status on our web
page. We will update those pages as new information becomes available.

And, we can't in good conscience fail to mention some [3]caveats to
using EGCS.

Update: Big thanks to Stanford for providing a high speed link for
downloading EGCS (go.cygnus.com)!

Download EGCS from ftp.cygnus.com (USA California) or go.cygnus.com
(USA California -- High speed link provided by Stanford).

The EGCS 1.0 release is also available many mirror sites.
[4]Goto mirror list to find a closer site

We'd like to thank the numerous people that have contributed new
features, test results, bugfixes, etc. Unfortunately, they're far too
numerous to mention by name.

For questions related to the use of GCC, please consult these web
pages and the [5]GCC manuals. If that fails, the
[6][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [7][email protected]. All of [8]our lists have public archives.

Copyright (C) [9]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [10]maintained by the GCC team. Last modified
2023-09-02.

References

1. https://gcc.gnu.org/egcs-1.0/features.html
2. https://gcc.gnu.org/egcs-1.0/buildstat.html
3. https://gcc.gnu.org/egcs-1.0/caveats.html
4. https://gcc.gnu.org/mirrors.html
5. https://gcc.gnu.org/onlinedocs/
6. mailto:[email protected]
7. mailto:[email protected]
8. https://gcc.gnu.org/lists.html
9. https://www.fsf.org/
10. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/egcs-1.0/features.html

EGCS 1.0 features

* Core compiler is based on the gcc2 development tree from Aug 2,
1997, so we have most of the [1]features found in GCC 2.8.
* Integrated GNU Fortran compiler based on g77-0.5.22-19970929.
* Vast improvements in the C++ compiler; so many they have [2]page of
their own!
* Integrated C++ runtime libraries, including support for most major
GNU/Linux systems!
* New instruction scheduler from IBM Haifa which includes support for
function wide instruction scheduling as well as superscalar
scheduling.
* Significantly improved alias analysis code.
* Improved register allocation for two address machines.
* Significant code generation improvements for Fortran code on
Alphas.
* Various optimizations from the g77 project as well as improved loop
optimizations.
* Dwarf2 debug format support for some targets.
* egcs libstdc++ includes the SGI STL implementation without changes.
* As a result of these and other changes, egcs libstc++ is not binary
compatible with previous releases of libstdc++.
* Various new ports -- UltraSPARC, Irix6.2 & Irix6.3 support, The SCO
Openserver 5 family (5.0.{0,2,4} and Internet FastStart 1.0 and
1.1), Support for RTEMS on several embedded targets, Support for
arm-linux, Mitsubishi M32R, Hitachi H8/S, Matsushita MN102 and
MN103, NEC V850, Sparclet, Solaris & GNU/Linux on PowerPCs, etc.
* Integrated testsuites for gcc, g++, g77, libstdc++ and libio.
* RS6000/PowerPC ports generate code which can run on all
RS6000/PowerPC variants by default.
* -mcpu= and -march= switches for the x86 port to allow better
control over how the x86 port generates code.
* Includes the template repository patch (aka repo patch); note the
new template code makes repo obsolete for ELF systems using gnu-ld
such as GNU/Linux.
* Plus the usual assortment of bugfixes and improvements.

For questions related to the use of GCC, please consult these web
pages and the [3]GCC manuals. If that fails, the
[4][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [5][email protected]. All of [6]our lists have public archives.

Copyright (C) [7]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [8]maintained by the GCC team. Last modified
2022-10-26.

References

1. https://gcc.gnu.org/egcs-1.0/features-2.8.html
2. https://gcc.gnu.org/egcs-1.0/c++features.html
3. https://gcc.gnu.org/onlinedocs/
4. mailto:[email protected]
5. mailto:[email protected]
6. https://gcc.gnu.org/lists.html
7. https://www.fsf.org/
8. https://gcc.gnu.org/about.html
======================================================================
http://gcc.gnu.org/egcs-1.0/caveats.html

EGCS 1.0 Caveats

* EGCS has an integrated libstdc++, but does not have an integrated
libg++. Furthermore old libg++ releases will not work with egc; HJ
Lu has made a libg++-2.8.1.2 available which may work with EGCS.
Note most C++ programs only need libstdc++.
* Note that using -pedantic or -Wreturn-type can cause an explosion
in the amount of memory needed for template-heavy C++ code, such as
code that uses STL. Also note that -Wall includes -Wreturn-type, so
if you use -Wall you will need to specify -Wno-return-type to turn
it off.
* Exception handling may not work with shared libraries, particularly
on alphas, hppas, and mips based platforms. Exception handling is
known to work on x86-linux platforms with shared libraries.
* Some versions of the Linux kernel have bugs which prevent them from
being compiled or from running when compiled by EGCS. See the FAQ
(as shipped with EGCS 1.0) for additional information.
* In general, EGCS is more rigorous about rejecting invalid C++ code
or deprecated C++ constructs than G++ 2.7. As a result it may be
necessary to fix C++ code before it will compile with EGCS.
* G++ is also aggressively tracking the C++ standard; as a result
code which was previously valid (and thus accepted by other
compilers and older versions of G++) may no longer be accepted.
* EGCS 1.0 may not work with Red Hat Linux 5.0 on all targets. EGCS
1.0.x and later releases should work with Red Hat Linux 5.0.

For questions related to the use of GCC, please consult these web
pages and the [1]GCC manuals. If that fails, the
[2][email protected] mailing list might help. Comments on these
web pages and the development of GCC are welcome on our developer
list at [3][email protected]. All of [4]our lists have public archives.

Copyright (C) [5]Free Software Foundation, Inc. Verbatim copying and
distribution of this entire article is permitted in any medium,
provided this notice is preserved.

These pages are [6]maintained by the GCC team. Last modified
2022-10-26.

References

1. https://gcc.gnu.org/onlinedocs/
2. mailto:[email protected]
3. mailto:[email protected]
4. https://gcc.gnu.org/lists.html
5. https://www.fsf.org/
6. https://gcc.gnu.org/about.html
======================================================================