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
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
|
/* Copyright (C) 2012-2014 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>
/* This file is included multiple times with required defines:
NAME the name of the operation that we're implementing;
OP a two-operand functional macro the implements the operation.
*/
/* If we support the builtin, just use it. */
#if !DONE && SIZE(HAVE_ATOMIC_FETCH_OP)
UTYPE
SIZE(C2(libat_fetch_,NAME)) (UTYPE *mptr, UTYPE opval, int smodel)
{
if (maybe_specialcase_relaxed(smodel))
return C2(__atomic_fetch_,NAME) (mptr, opval, __ATOMIC_RELAXED);
else if (maybe_specialcase_acqrel(smodel))
return C2(__atomic_fetch_,NAME) (mptr, opval, __ATOMIC_ACQ_REL);
else
return C2(__atomic_fetch_,NAME) (mptr, opval, __ATOMIC_SEQ_CST);
}
UTYPE
SIZE(C3(libat_,NAME,_fetch)) (UTYPE *mptr, UTYPE opval, int smodel)
{
if (maybe_specialcase_relaxed(smodel))
return C3(__atomic_,NAME,_fetch) (mptr, opval, __ATOMIC_RELAXED);
else if (maybe_specialcase_acqrel(smodel))
return C3(__atomic_,NAME,_fetch) (mptr, opval, __ATOMIC_ACQ_REL);
else
return C3(__atomic_,NAME,_fetch) (mptr, opval, __ATOMIC_SEQ_CST);
}
#define DONE 1
#endif /* HAVE_ATOMIC_FETCH_OP */
#if !DONE && defined(atomic_compare_exchange_n)
UTYPE
SIZE(C2(libat_fetch_,NAME)) (UTYPE *mptr, UTYPE opval, int smodel)
{
UTYPE oldval, t;
pre_barrier (smodel);
oldval = *mptr;
do
{
t = OP(oldval, opval);
}
while (!atomic_compare_exchange_n (mptr, &oldval, t, true,
__ATOMIC_RELAXED, __ATOMIC_RELAXED));
post_barrier (smodel);
return oldval;
}
UTYPE
SIZE(C3(libat_,NAME,_fetch)) (UTYPE *mptr, UTYPE opval, int smodel)
{
UTYPE oldval, t;
pre_barrier (smodel);
oldval = *mptr;
do
{
t = OP(oldval, opval);
}
while (!atomic_compare_exchange_n (mptr, &oldval, t, true,
__ATOMIC_RELAXED, __ATOMIC_RELAXED));
post_barrier (smodel);
return t;
}
#define DONE 1
#endif /* atomic_compare_exchange_n */
/* If this type is no larger than word-sized, fall back to a word-sized
compare-and-swap loop. */
#if !DONE && N < WORDSIZE && defined(atomic_compare_exchange_w)
UTYPE
SIZE(C2(libat_fetch_,NAME)) (UTYPE *mptr, UTYPE opval, int smodel)
{
UWORD mask, shift, woldval, wopval, 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;
wopval = (UWORD)opval << shift;
woldval = __atomic_load_n (wptr, __ATOMIC_RELAXED);
do
{
t = (woldval & ~mask) | (OP(woldval, wopval) & mask);
}
while (!atomic_compare_exchange_w (wptr, &woldval, t, true,
__ATOMIC_RELAXED, __ATOMIC_RELAXED));
post_barrier (smodel);
return woldval >> shift;
}
UTYPE
SIZE(C3(libat_,NAME,_fetch)) (UTYPE *mptr, UTYPE opval, int smodel)
{
UWORD mask, shift, woldval, wopval, 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;
wopval = (UWORD)opval << shift;
woldval = __atomic_load_n (wptr, __ATOMIC_RELAXED);
do
{
t = (woldval & ~mask) | (OP(woldval, wopval) & mask);
}
while (!atomic_compare_exchange_w (wptr, &woldval, t, true,
__ATOMIC_RELAXED, __ATOMIC_RELAXED));
post_barrier (smodel);
return t >> shift;
}
#define DONE 1
#endif /* atomic_compare_exchange_w */
/* Otherwise, fall back to some sort of protection mechanism. */
#if !DONE
UTYPE
SIZE(C2(libat_fetch_,NAME)) (UTYPE *mptr, UTYPE opval, int smodel UNUSED)
{
UTYPE ret;
UWORD magic;
pre_seq_barrier (smodel);
magic = protect_start (mptr);
ret = *mptr;
*mptr = OP(ret, opval);
protect_end (mptr, magic);
post_seq_barrier (smodel);
return ret;
}
UTYPE
SIZE(C3(libat_,NAME,_fetch)) (UTYPE *mptr, UTYPE opval, int smodel UNUSED)
{
UTYPE ret;
UWORD magic;
pre_seq_barrier (smodel);
magic = protect_start (mptr);
ret = OP (*mptr, opval);
*mptr = ret;
protect_end (mptr, magic);
post_seq_barrier (smodel);
return ret;
}
#endif
EXPORT_ALIAS (SIZE(C2(fetch_,NAME)));
EXPORT_ALIAS (SIZE(C2(NAME,_fetch)));
|
