1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
|
/* Copyright (C) 2012-2016 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_LDST)
void
SIZE(libat_store) (UTYPE *mptr, UTYPE newval, int smodel)
{
if (maybe_specialcase_relaxed(smodel))
__atomic_store_n (mptr, newval, __ATOMIC_RELAXED);
else if (maybe_specialcase_acqrel(smodel))
/* Note that ACQ and ACQ_REL are not valid for store. */
__atomic_store_n (mptr, newval, __ATOMIC_RELEASE);
else
__atomic_store_n (mptr, newval, __ATOMIC_SEQ_CST);
}
#define DONE 1
#endif /* HAVE_ATOMIC_STORE */
/* If we have compare-and-swap, use it perform the store. */
#if !DONE && defined(atomic_compare_exchange_n)
void
SIZE(libat_store) (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);
}
#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)
void
SIZE(libat_store) (UTYPE *mptr, UTYPE newval, int smodel)
{
UWORD mask, shift, woldval, wnewval, t, *wptr;
pre_barrier (smodel);
wptr = (UWORD *)((uintptr_t)mptr & -WORDSIZE);
shift = (((uintptr_t)mptr % WORDSIZE) * CHAR_BIT) ^ SIZE(INVERT_MASK);
mask = SIZE(MASK) << shift;
wnewval = (UWORD)newval << shift;
woldval = __atomic_load_n (wptr, __ATOMIC_RELAXED);
do
{
t = (woldval & ~mask) | wnewval;
}
while (!atomic_compare_exchange_w (wptr, &woldval, t));
post_barrier (smodel);
}
#define DONE 1
#endif /* N < WORDSIZE && atomic_compare_exchange_w */
/* Otherwise, fall back to some sort of protection mechanism. */
#if !DONE
void
SIZE(libat_store) (UTYPE *mptr, UTYPE newval, int smodel)
{
UWORD magic;
pre_seq_barrier (smodel);
magic = protect_start (mptr);
*mptr = newval;
protect_end (mptr, magic);
post_seq_barrier (smodel);
}
#endif
EXPORT_ALIAS (SIZE(store));
|
