[-fcompare-debug] var tracking options are not optimization options
[official-gcc.git] / libatomic / store_n.c
blob52c917f64df211051aee4d773357420312885376
1 /* Copyright (C) 2012-2017 Free Software Foundation, Inc.
2 Contributed by Richard Henderson <rth@redhat.com>.
4 This file is part of the GNU Atomic Library (libatomic).
6 Libatomic is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
11 Libatomic is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
13 FOR A PARTICULAR PURPOSE. See the GNU General Public License for
14 more details.
16 Under Section 7 of GPL version 3, you are granted additional
17 permissions described in the GCC Runtime Library Exception, version
18 3.1, as published by the Free Software Foundation.
20 You should have received a copy of the GNU General Public License and
21 a copy of the GCC Runtime Library Exception along with this program;
22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 <http://www.gnu.org/licenses/>. */
25 #include "libatomic_i.h"
28 /* If we support the builtin, just use it. */
29 #if !DONE && SIZE(HAVE_ATOMIC_LDST)
30 void
31 SIZE(libat_store) (UTYPE *mptr, UTYPE newval, int smodel)
33 if (maybe_specialcase_relaxed(smodel))
34 __atomic_store_n (mptr, newval, __ATOMIC_RELAXED);
35 else if (maybe_specialcase_acqrel(smodel))
36 /* Note that ACQ and ACQ_REL are not valid for store. */
37 __atomic_store_n (mptr, newval, __ATOMIC_RELEASE);
38 else
39 __atomic_store_n (mptr, newval, __ATOMIC_SEQ_CST);
42 #define DONE 1
43 #endif /* HAVE_ATOMIC_STORE */
45 /* If we have compare-and-swap, use it perform the store. */
46 #if !DONE && defined(atomic_compare_exchange_n)
47 void
48 SIZE(libat_store) (UTYPE *mptr, UTYPE newval, int smodel)
50 UTYPE oldval;
52 pre_barrier (smodel);
54 oldval = *mptr;
55 while (!atomic_compare_exchange_n (mptr, &oldval, newval, true,
56 __ATOMIC_RELAXED, __ATOMIC_RELAXED))
57 continue;
59 post_barrier (smodel);
62 #define DONE 1
63 #endif /* atomic_compare_exchange_n */
66 /* If this type is smaller than word-sized, fall back to a word-sized
67 compare-and-swap loop. */
68 #if !DONE && N < WORDSIZE && defined(atomic_compare_exchange_w)
69 void
70 SIZE(libat_store) (UTYPE *mptr, UTYPE newval, int smodel)
72 UWORD mask, shift, woldval, wnewval, t, *wptr;
74 pre_barrier (smodel);
76 wptr = (UWORD *)((uintptr_t)mptr & -WORDSIZE);
77 shift = (((uintptr_t)mptr % WORDSIZE) * CHAR_BIT) ^ SIZE(INVERT_MASK);
78 mask = SIZE(MASK) << shift;
80 wnewval = (UWORD)newval << shift;
81 woldval = __atomic_load_n (wptr, __ATOMIC_RELAXED);
84 t = (woldval & ~mask) | wnewval;
86 while (!atomic_compare_exchange_w (wptr, &woldval, t));
88 post_barrier (smodel);
91 #define DONE 1
92 #endif /* N < WORDSIZE && atomic_compare_exchange_w */
95 /* Otherwise, fall back to some sort of protection mechanism. */
96 #if !DONE
97 void
98 SIZE(libat_store) (UTYPE *mptr, UTYPE newval, int smodel)
100 UWORD magic;
102 pre_seq_barrier (smodel);
103 magic = protect_start (mptr);
105 *mptr = newval;
107 protect_end (mptr, magic);
108 post_seq_barrier (smodel);
110 #endif
112 EXPORT_ALIAS (SIZE(store));