GAS is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GAS is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GAS; see the file COPYING. If not, write to the Free
Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
02110-1301, USA. */
/* Check that we're not trying to assemble into a section that can't
allocate frags (currently, this is only possible in the absolute
section), or into an mri common. */
static void
frag_alloc_check (const struct obstack *ob)
{
if (ob->chunk_size == 0)
{
as_bad (_("attempt to allocate data in absolute section"));
subseg_set (text_section, 0);
}
if (mri_common_symbol != NULL)
{
as_bad (_("attempt to allocate data in common section"));
mri_common_symbol = NULL;
}
}
/* Allocate a frag on the specified obstack.
Call this routine from everywhere else, so that all the weird alignment
hackery can be done in just one place. */
/* Try to augment current frag by nchars chars.
If there is no room, close off the current frag with a ".fill 0"
and begin a new frag. Then loop until the new frag has at least
nchars chars available. Does not set up any fields in frag_now. */
/* Try to allocate a bit more than needed right now. But don't do
this if we would waste too much memory. Especially necessary
for extremely big (like 2GB initialized) frags. */
if (nchars < 0x10000)
newc = 2 * nchars;
else
newc = nchars + 0x10000;
newc += SIZEOF_STRUCT_FRAG;
/* Check for possible overflow. */
if (newc < nchars)
as_fatal (ngettext ("can't extend frag %lu char",
"can't extend frag %lu chars",
(unsigned long) nchars),
(unsigned long) nchars);
/* Force to allocate at least NEWC bytes, but not less than the
default. */
oldc = obstack_chunk_size (&frchain_now->frch_obstack);
if (newc > oldc)
obstack_chunk_size (&frchain_now->frch_obstack) = newc;
while (obstack_room (&frchain_now->frch_obstack) < nchars)
{
/* Not enough room in this frag. Close it and start a new one.
This must be done in a loop because the created frag may not
be big enough if the current obstack chunk is used. */
frag_wane (frag_now);
frag_new (0);
}
/* Restore the old chunk size. */
obstack_chunk_size (&frchain_now->frch_obstack) = oldc;
}
}
/* Call this to close off a completed frag, and start up a new (empty)
frag, in the same subsegment as the old frag.
[frchain_now remains the same but frag_now is updated.]
Because this calculates the correct value of fr_fix by
looking at the obstack 'frags', it needs to know how many
characters at the end of the old frag belong to the maximal
variable part; The rest must belong to fr_fix.
It doesn't actually set up the old frag's fr_var. You may have
set fr_var == 1, but allocated 10 chars to the end of the frag;
In this case you pass old_frags_var_max_size == 10.
In fact, you may use fr_var for something totally unrelated to the
size of the variable part of the frag; None of the generic frag
handling code makes use of fr_var.
Make a new frag, initialising some components. Link new frag at end
of frchain_now. */
void
frag_new (size_t old_frags_var_max_size
/* Number of chars (already allocated on obstack frags) in
variable_length part of frag. */)
{
fragS *former_last_fragP;
frchainS *frchP;
gas_assert (frchain_now->frch_last == frag_now);
/* Fix up old frag's fr_fix. */
frag_now->fr_fix = frag_now_fix_octets ();
gas_assert (frag_now->fr_fix >= old_frags_var_max_size
|| now_seg == absolute_section);
frag_now->fr_fix -= old_frags_var_max_size;
/* Make sure its type is valid. */
gas_assert (frag_now->fr_type != 0);
/* This will align the obstack so the next struct we allocate on it
will begin at a correct boundary. */
obstack_finish (&frchain_now->frch_obstack);
frchP = frchain_now;
know (frchP);
former_last_fragP = frchP->frch_last;
gas_assert (former_last_fragP != 0);
gas_assert (former_last_fragP == frag_now);
frag_now = frag_alloc (&frchP->frch_obstack);
/* Generally, frag_now->points to an address rounded up to next
alignment. However, characters will add to obstack frags
IMMEDIATELY after the struct frag, even if they are not starting
at an alignment address. */
former_last_fragP->fr_next = frag_now;
frchP->frch_last = frag_now;
/* Make an alignment frag. The size of this frag will be adjusted to
force the next frag to have the appropriate alignment. ALIGNMENT
is the power of two to which to align. FILL_CHARACTER is the
character to use to fill in any bytes which are skipped. MAX is
the maximum number of characters to skip when doing the alignment,
or 0 if there is no maximum. */
void
frag_align (int alignment, int fill_character, int max)
{
if (now_seg == absolute_section)
{
addressT new_off;
addressT mask;
/* Make an alignment frag like frag_align, but fill with a repeating
pattern rather than a single byte. ALIGNMENT is the power of two
to which to align. FILL_PATTERN is the fill pattern to repeat in
the bytes which are skipped. N_FILL is the number of bytes in
FILL_PATTERN. MAX is the maximum number of characters to skip when
doing the alignment, or 0 if there is no maximum. */
/* The NOP_OPCODE is for the alignment fill value. Fill it with a nop
instruction so that the disassembler does not choke on it. */
#ifndef NOP_OPCODE
#define NOP_OPCODE 0x00
#endif
/* Use this to restrict the amount of memory allocated for representing
the alignment code. Needs to be large enough to hold any fixed sized
prologue plus the replicating portion. */
#ifndef MAX_MEM_FOR_RS_ALIGN_CODE
/* Assume that if HANDLE_ALIGN is not defined then no special action
is required to code fill, which means that we get just repeat the
one NOP_OPCODE byte. */
# ifndef HANDLE_ALIGN
# define MAX_MEM_FOR_RS_ALIGN_CODE 1
# else
# define MAX_MEM_FOR_RS_ALIGN_CODE (((size_t) 1 << alignment) - 1)
# endif
#endif
void
frag_align_code (int alignment, int max)
{
char *p;
/* Return TRUE if FRAG1 and FRAG2 have a fixed relationship between
their start addresses. Set OFFSET to the difference in address
not already accounted for in the frag FR_ADDRESS. */
/* Start with offset initialised to difference between the two frags.
Prior to assigning frag addresses this will be zero. */
off = frag1->fr_address - frag2->fr_address;
if (frag1 == frag2)
{
*offset = off;
return true;
}
/* Maybe frag2 is after frag1. */
frag = frag1;
while (frag->fr_type == rs_fill)
{
off += frag->fr_fix + frag->fr_offset * frag->fr_var;
frag = frag->fr_next;
if (frag == NULL)
break;
if (frag == frag2)
{
*offset = off;
return true;
}
}
/* Maybe frag1 is after frag2. */
off = frag1->fr_address - frag2->fr_address;
frag = frag2;
while (frag->fr_type == rs_fill)
{
off -= frag->fr_fix + frag->fr_offset * frag->fr_var;
frag = frag->fr_next;
if (frag == NULL)
break;
if (frag == frag1)
{
*offset = off;
return true;
}
}
return false;
}
/* Return TRUE if FRAG2 follows FRAG1 with a fixed relationship
between the two assuming alignment frags do nothing. Set OFFSET to
the difference in address not already accounted for in the frag
FR_ADDRESS. */
/* Start with offset initialised to difference between the two frags.
Prior to assigning frag addresses this will be zero. */
off = frag1->fr_address - frag2->fr_address;
if (frag1 == frag2)
{
*offset = off;
return true;
}
/* Return TRUE if we can determine whether FRAG2 OFF2 appears after
(strict >, not >=) FRAG1 OFF1, assuming it is not before. Set
*OFFSET so that resolve_expression will resolve an O_gt operation
between them to false (0) if they are guaranteed to be at the same
location, or to true (-1) if they are guaranteed to be at different
locations. Return FALSE conservatively, e.g. if neither result can
be guaranteed (yet).
They are known to be in the same segment, and not the same frag
(this is a fallback for frag_offset_fixed_p, that always takes care
of this case), and it is expected (from the uses this is designed
to simplify, namely location view increments) that frag2 is
reachable from frag1 following the fr_next links, rather than the
other way round. */
/* If the first symbol offset is at the end of the first frag and
the second symbol offset at the beginning of the second frag then
it is possible they are at the same address. Go looking for a
non-zero fr_fix in any frag between these frags. If found then
we can say the O_gt result will be true. If no such frag is
found we assume that frag1 or any of the following frags might
have a variable tail and thus the answer is unknown. This isn't
strictly true; some frags don't have a variable tail, but it
doesn't seem worth optimizing for those cases. */
const fragS *frag = frag1;
offsetT delta = off2 - off1;
for (;;)
{
delta += frag->fr_fix;
frag = frag->fr_next;
if (frag == frag2)
{
if (delta == 0)
return false;
break;
}
/* If we run off the end of the frag chain then we have a case
where frag2 is not after frag1, ie. an O_gt expression not
created for .loc view. */
if (frag == NULL)
return false;
}
