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8d9254fc | 1 | /* Copyright (C) 2008-2020 Free Software Foundation, Inc. |
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2 | Contributed by Jakub Jelinek <jakub@redhat.com>. |
3 | ||
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4 | This file is part of the GNU Offloading and Multi Processing Library |
5 | (libgomp). | |
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6 | |
7 | Libgomp is free software; you can redistribute it and/or modify it | |
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8 | under the terms of the GNU General Public License as published by |
9 | the Free Software Foundation; either version 3, or (at your option) | |
10 | any later version. | |
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11 | |
12 | Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS | |
748086b7 | 14 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
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15 | more details. |
16 | ||
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17 | Under Section 7 of GPL version 3, you are granted additional |
18 | permissions described in the GCC Runtime Library Exception, version | |
19 | 3.1, as published by the Free Software Foundation. | |
20 | ||
21 | You should have received a copy of the GNU General Public License and | |
22 | a copy of the GCC Runtime Library Exception along with this program; | |
23 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
24 | <http://www.gnu.org/licenses/>. */ | |
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25 | |
26 | /* This is a Linux specific implementation of a mutex synchronization | |
27 | mechanism for libgomp. This type is private to the library. This | |
28 | implementation uses atomic instructions and the futex syscall. */ | |
29 | ||
30 | #ifndef GOMP_WAIT_H | |
31 | #define GOMP_WAIT_H 1 | |
32 | ||
33 | #include "libgomp.h" | |
34 | #include <errno.h> | |
35 | ||
36 | #define FUTEX_WAIT 0 | |
37 | #define FUTEX_WAKE 1 | |
8ed501f1 | 38 | #define FUTEX_PRIVATE_FLAG 128 |
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39 | |
40 | #ifdef HAVE_ATTRIBUTE_VISIBILITY | |
41 | # pragma GCC visibility push(hidden) | |
42 | #endif | |
43 | ||
8ed501f1 | 44 | extern int gomp_futex_wait, gomp_futex_wake; |
a68ab351 | 45 | |
53b4d41d | 46 | #include <futex.h> |
a68ab351 | 47 | |
bfee0724 | 48 | static inline int do_spin (int *addr, int val) |
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49 | { |
50 | unsigned long long i, count = gomp_spin_count_var; | |
51 | ||
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52 | if (__builtin_expect (__atomic_load_n (&gomp_managed_threads, |
53 | MEMMODEL_RELAXED) | |
54 | > gomp_available_cpus, 0)) | |
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55 | count = gomp_throttled_spin_count_var; |
56 | for (i = 0; i < count; i++) | |
3b35cd04 | 57 | if (__builtin_expect (__atomic_load_n (addr, MEMMODEL_RELAXED) != val, 0)) |
bfee0724 | 58 | return 0; |
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59 | else |
60 | cpu_relax (); | |
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61 | return 1; |
62 | } | |
63 | ||
64 | static inline void do_wait (int *addr, int val) | |
65 | { | |
66 | if (do_spin (addr, val)) | |
67 | futex_wait (addr, val); | |
a68ab351 JJ |
68 | } |
69 | ||
70 | #ifdef HAVE_ATTRIBUTE_VISIBILITY | |
71 | # pragma GCC visibility pop | |
72 | #endif | |
73 | ||
74 | #endif /* GOMP_WAIT_H */ |