mirror of
https://gcc.gnu.org/git/gcc.git
synced 2024-11-27 22:03:57 +08:00
129 lines
3.3 KiB
C
129 lines
3.3 KiB
C
/* Copyright (C) 2012-2020 Free Software Foundation, Inc.
|
|
Contributed by Richard Henderson <rth@redhat.com>.
|
|
|
|
This file is part of the GNU Atomic Library (libatomic).
|
|
|
|
Libatomic 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 of the License, or
|
|
(at your option) any later version.
|
|
|
|
Libatomic 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.
|
|
|
|
Under Section 7 of GPL version 3, you are granted additional
|
|
permissions described in the GCC Runtime Library Exception, version
|
|
3.1, as published by the Free Software Foundation.
|
|
|
|
You should have received a copy of the GNU General Public License and
|
|
a copy of the GCC Runtime Library Exception along with this program;
|
|
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
#include "libatomic_i.h"
|
|
|
|
|
|
/* If we support the builtin, just use it. */
|
|
#if !DONE && SIZE(HAVE_ATOMIC_EXCHANGE)
|
|
UTYPE
|
|
SIZE(libat_exchange) (UTYPE *mptr, UTYPE newval, int smodel)
|
|
{
|
|
if (maybe_specialcase_relaxed(smodel))
|
|
return __atomic_exchange_n (mptr, newval, __ATOMIC_RELAXED);
|
|
else if (maybe_specialcase_acqrel(smodel))
|
|
return __atomic_exchange_n (mptr, newval, __ATOMIC_ACQ_REL);
|
|
else
|
|
return __atomic_exchange_n (mptr, newval, __ATOMIC_SEQ_CST);
|
|
}
|
|
|
|
#define DONE 1
|
|
#endif /* HAVE_ATOMIC_EXCHANGE */
|
|
|
|
|
|
#if !DONE && defined(atomic_compare_exchange_n)
|
|
UTYPE
|
|
SIZE(libat_exchange) (UTYPE *mptr, UTYPE newval, int smodel)
|
|
{
|
|
UTYPE oldval;
|
|
|
|
pre_barrier (smodel);
|
|
|
|
oldval = *mptr;
|
|
while (!atomic_compare_exchange_n (mptr, &oldval, newval, true,
|
|
__ATOMIC_RELAXED, __ATOMIC_RELAXED))
|
|
continue;
|
|
|
|
post_barrier (smodel);
|
|
|
|
return oldval;
|
|
}
|
|
|
|
#define DONE 1
|
|
#endif /* atomic_compare_exchange_n */
|
|
|
|
|
|
/* If this type is smaller than word-sized, fall back to a word-sized
|
|
compare-and-swap loop. */
|
|
#if !DONE && N <= WORDSIZE && defined(atomic_compare_exchange_w)
|
|
UTYPE
|
|
SIZE(libat_exchange) (UTYPE *mptr, UTYPE newval, int smodel)
|
|
{
|
|
UWORD mask, shift, woldval, wnewval, t, *wptr;
|
|
|
|
pre_barrier (smodel);
|
|
|
|
if (N < WORDSIZE)
|
|
{
|
|
wptr = (UWORD *)((uintptr_t)mptr & -WORDSIZE);
|
|
shift = (((uintptr_t)mptr % WORDSIZE) * CHAR_BIT) ^ SIZE(INVERT_MASK);
|
|
mask = SIZE(MASK) << shift;
|
|
}
|
|
else
|
|
{
|
|
wptr = (UWORD *)mptr;
|
|
shift = 0;
|
|
mask = -1;
|
|
}
|
|
|
|
wnewval = (UWORD)newval << shift;
|
|
woldval = __atomic_load_n (wptr, __ATOMIC_RELAXED);
|
|
do
|
|
{
|
|
t = (woldval & ~mask) | wnewval;
|
|
}
|
|
while (!atomic_compare_exchange_w (wptr, &woldval, t, true,
|
|
__ATOMIC_RELAXED, __ATOMIC_RELAXED));
|
|
|
|
post_barrier (smodel);
|
|
return woldval >> shift;
|
|
}
|
|
|
|
#define DONE 1
|
|
#endif /* HAVE_ATOMIC_CAS && N < WORDSIZE */
|
|
|
|
|
|
/* Otherwise, fall back to some sort of protection mechanism. */
|
|
#if !DONE
|
|
UTYPE
|
|
SIZE(libat_exchange) (UTYPE *mptr, UTYPE newval, int smodel UNUSED)
|
|
{
|
|
UTYPE oldval;
|
|
UWORD magic;
|
|
|
|
pre_seq_barrier (smodel);
|
|
magic = protect_start (mptr);
|
|
|
|
oldval = *mptr;
|
|
*mptr = newval;
|
|
|
|
protect_end (mptr, magic);
|
|
post_seq_barrier (smodel);
|
|
|
|
return oldval;
|
|
}
|
|
#endif
|
|
|
|
EXPORT_ALIAS (SIZE(exchange));
|