-
Notifications
You must be signed in to change notification settings - Fork 67
/
sqMemoryFence.h
70 lines (66 loc) · 2.8 KB
/
sqMemoryFence.h
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
/* sqMemoryFence.h
* Support for synchronisation above weakly-ordered memory models.
*
* Author: Eliot Miranda
*
* Copyright (c) 2013 3D Immersive Collaboration Consulting, LLC.
*
* All rights reserved.
*
* This file is part of Squeak.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
/* sqLowLevelMFence is required to ensure that after completion any stores made
* by other threads before a fence will be visible to the calling thread, and
* vice versa. Writers follow a write with a fence. Readers use a fence before
* reading. See e.g. http://en.wikipedia.org/wiki/Memory_barrier
*/
#if defined(__GNUC__)
# define GCC_HAS_BUILTIN_SYNC \
(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1))
# define GCC_HAS_BUILTIN_ATOMIC \
(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 7))
#endif
#if defined(__GNUC__) || defined(__clang__)
# if GCC_HAS_BUILTIN_SYNC || defined(__clang__)
# define sqLowLevelMFence() __sync_synchronize()
# elif defined(i386) || defined(__i386) || defined(__i386__) || defined(_X86_)
# if defined(__MINGW32__) && !__SSE2__
/* Andreas is fond of the gcc 2.95 MINGW but it lacks sse2 support */
# define sqLowLevelMFence() asm volatile (".byte 0x0f;.byte 0xae;.byte 0xf0")
# else
# define sqLowLevelMFence() asm volatile ("mfence")
# endif
# endif
#elif defined(_MSC_VER)
/* # define sqLowLevelMFence() _asm { mfence } */
/* could use mfence here but */ \
/* See http://shipilev.net/blog/2014/on-the-fence-with-dependencies/ */ \
# if defined(_M_IX86) || defined(_X86_)
# define sqLowLevelMFence() __asm { \
__asm lock add [esp], 0 \
}
# elif defined(_WIN64) || defined(_M_X64) || defined(_M_AMD64)
# define sqLowLevelMFence MemoryBarrier
# endif
#endif
#if !defined(sqLowLevelMFence)
extern void sqLowLevelMFence(void);
#endif