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99dee823 | 1 | /* Copyright (C) 2012-2021 Free Software Foundation, Inc. |
48310492 RH |
2 | Contributed by Richard Henderson <rth@redhat.com>. |
3 | ||
4 | This file is part of the GNU Atomic Library (libatomic). | |
5 | ||
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. | |
10 | ||
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. | |
15 | ||
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. | |
19 | ||
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/>. */ | |
24 | ||
25 | /* Included after all more target-specific host-config.h. */ | |
26 | ||
27 | ||
28 | /* The target may have some OS specific way to implement compare-and-swap. */ | |
29 | #if !defined(atomic_compare_exchange_n) && SIZE(HAVE_ATOMIC_CAS) | |
30 | # define atomic_compare_exchange_n __atomic_compare_exchange_n | |
31 | #endif | |
32 | #if !defined(atomic_compare_exchange_w) && WSIZE(HAVE_ATOMIC_CAS) | |
33 | # define atomic_compare_exchange_w __atomic_compare_exchange_n | |
34 | #endif | |
35 | ||
36 | /* For some targets, it may be significantly faster to avoid all barriers | |
37 | if the user only wants relaxed memory order. Sometimes we don't want | |
38 | the extra code bloat. In all cases, use the input to avoid warnings. */ | |
39 | #if defined(WANT_SPECIALCASE_RELAXED) && !defined(__OPTIMIZE_SIZE__) | |
40 | # define maybe_specialcase_relaxed(x) ((x) == __ATOMIC_RELAXED) | |
41 | #else | |
42 | # define maybe_specialcase_relaxed(x) ((x) & 0) | |
43 | #endif | |
44 | ||
45 | /* Similar, but for targets for which the seq_cst model is sufficiently | |
46 | more expensive than the acq_rel model. */ | |
47 | #if defined(WANT_SPECIALCASE_ACQREL) && !defined(__OPTIMIZE_SIZE__) | |
48 | # define maybe_specialcase_acqrel(x) ((x) != __ATOMIC_SEQ_CST) | |
49 | #else | |
50 | # define maybe_specialcase_acqrel(x) ((x) & 0) | |
51 | #endif | |
52 | ||
53 | ||
54 | /* The target may have some OS specific way to emit barriers. */ | |
55 | #ifndef pre_post_barrier | |
56 | static inline void __attribute__((always_inline, artificial)) | |
57 | pre_barrier(int model) | |
58 | { | |
59 | if (!maybe_specialcase_relaxed(model)) | |
60 | { | |
61 | if (maybe_specialcase_acqrel(model)) | |
62 | __atomic_thread_fence (__ATOMIC_ACQ_REL); | |
63 | else | |
64 | __atomic_thread_fence (__ATOMIC_SEQ_CST); | |
65 | } | |
66 | } | |
67 | static inline void __attribute__((always_inline, artificial)) | |
68 | post_barrier(int model) | |
69 | { | |
70 | pre_barrier(model); | |
71 | } | |
72 | #define pre_post_barrier 1 | |
73 | #endif /* pre_post_barrier */ | |
74 | ||
75 | /* Similar, but assume that acq_rel is already handled via locks. */ | |
76 | #ifndef pre_post_seq_barrier | |
77 | static inline void __attribute__((always_inline, artificial)) | |
78 | pre_seq_barrier(int model) | |
79 | { | |
80 | } | |
81 | static inline void __attribute__((always_inline, artificial)) | |
82 | post_seq_barrier(int model) | |
83 | { | |
84 | } | |
85 | #define pre_post_seq_barrier 1 | |
86 | #endif |