/*
* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
* Copyright (c) 1996-1999 by Silicon Graphics. All rights reserved.
* Copyright (c) 1999-2003 by Hewlett-Packard Company. All rights reserved.
*
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose, provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*
*/
#if (AO_GNUC_PREREQ(5, 4) || AO_CLANG_PREREQ(8, 0)) && defined(__s390x__) \
&& !defined(AO_DISABLE_GCC_ATOMICS)
/* Probably, it could be enabled for earlier clang/gcc versions. */
/* But, e.g., clang-3.8.0 produces a backend error for AtomicFence. */
# include "generic.h"
#else /* AO_DISABLE_GCC_ATOMICS */
/* The relevant documentation appears to be at */
/*
http://publibz.boulder.ibm.com/epubs/pdf/dz9zr003.pdf */
/* around page 5-96. Apparently: */
/* - Memory references in general are atomic only for a single */
/* byte. But it appears that the most common load/store */
/* instructions also guarantee atomicity for aligned */
/* operands of standard types. WE FOOLISHLY ASSUME that */
/* compilers only generate those. If that turns out to be */
/* wrong, we need inline assembly code for AO_load and */
/* AO_store. */
/* - A store followed by a load is unordered since the store */
/* may be delayed. Otherwise everything is ordered. */
/* - There is a hardware compare-and-swap (CS) instruction. */
#include "../all_aligned_atomic_load_store.h"
#include "../ordered_except_wr.h"
#include "../test_and_set_t_is_ao_t.h"
/* TODO: Is there a way to do byte-sized test-and-set? */
/* TODO: AO_nop_full should probably be implemented directly. */
/* It appears that certain BCR instructions have that effect. */
/* Presumably they're cheaper than CS? */
#ifndef AO_GENERALIZE_ASM_BOOL_CAS
AO_INLINE int AO_compare_and_swap_full(volatile AO_t *addr,
AO_t old, AO_t new_val)
{
int retval;
__asm__ __volatile__ (
# ifndef __s390x__
" cs %1,%2,0(%3)\n"
# else
" csg %1,%2,0(%3)\n"
# endif
" ipm %0\n"
" srl %0,28\n"
: "=&d" (retval), "+d" (old)
: "d" (new_val), "a" (addr)
: "cc", "memory");
return retval == 0;
}
#define AO_HAVE_compare_and_swap_full
#endif /* !AO_GENERALIZE_ASM_BOOL_CAS */
AO_INLINE AO_t
AO_fetch_compare_and_swap_full(volatile AO_t *addr,
AO_t old, AO_t new_val)
{
__asm__ __volatile__ (
# ifndef __s390x__
" cs %0,%2,%1\n"
# else
" csg %0,%2,%1\n"
# endif
: "+d" (old), "=Q" (*addr)
: "d" (new_val), "m" (*addr)
: "cc", "memory");
return old;
}
#define AO_HAVE_fetch_compare_and_swap_full
#endif /* AO_DISABLE_GCC_ATOMICS */
/* TODO: Add double-wide operations for 32-bit executables. */
