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8d9254fc | 1 | /* Copyright (C) 2012-2020 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 | #include "libatomic_i.h" | |
26 | ||
27 | ||
28 | /* If we support the builtin, just use it. */ | |
29 | #if !DONE && SIZE(HAVE_ATOMIC_TAS) | |
30 | bool | |
31 | SIZE(libat_test_and_set) (UTYPE *mptr, int smodel) | |
32 | { | |
33 | if (maybe_specialcase_relaxed(smodel)) | |
34 | return __atomic_test_and_set (mptr, __ATOMIC_RELAXED); | |
35 | else if (maybe_specialcase_acqrel(smodel)) | |
36 | return __atomic_test_and_set (mptr, __ATOMIC_ACQ_REL); | |
37 | else | |
38 | return __atomic_test_and_set (mptr, __ATOMIC_SEQ_CST); | |
39 | } | |
40 | ||
41 | #define DONE 1 | |
42 | #endif /* HAVE_ATOMIC_TAS */ | |
43 | ||
44 | ||
45 | /* If this type is smaller than word-sized, fall back to a word-sized | |
46 | compare-and-swap loop. */ | |
47 | #if !DONE && N <= WORDSIZE && defined(atomic_compare_exchange_w) | |
48 | bool | |
49 | SIZE(libat_test_and_set) (UTYPE *mptr, int smodel) | |
50 | { | |
51 | UWORD wval, woldval, shift, *wptr, t; | |
52 | ||
53 | pre_barrier (smodel); | |
54 | ||
55 | if (N < WORDSIZE) | |
56 | { | |
57 | wptr = (UWORD *)((uintptr_t)mptr & -WORDSIZE); | |
58 | shift = SIZE(INVERT_MASK); | |
59 | } | |
60 | else | |
61 | { | |
62 | wptr = (UWORD *)mptr; | |
63 | shift = 0; | |
64 | } | |
65 | ||
66 | wval = (UWORD)__GCC_ATOMIC_TEST_AND_SET_TRUEVAL << shift; | |
67 | woldval = __atomic_load_n (wptr, __ATOMIC_RELAXED); | |
68 | do | |
69 | { | |
70 | t = woldval | wval; | |
71 | } | |
72 | while (!atomic_compare_exchange_w (wptr, &woldval, t, true, | |
73 | __ATOMIC_RELAXED, __ATOMIC_RELAXED)); | |
74 | ||
75 | post_barrier (smodel); | |
76 | return woldval != 0; | |
77 | } | |
78 | ||
79 | #define DONE 1 | |
80 | #endif /* HAVE_ATOMIC_CAS && N < WORDSIZE */ | |
81 | ||
82 | ||
83 | /* Otherwise, fall back to some sort of protection mechanism. */ | |
84 | #if !DONE && N == 1 | |
85 | bool | |
86 | SIZE(libat_test_and_set) (UTYPE *mptr, int smodel) | |
87 | { | |
91734423 | 88 | UTYPE oldval; |
48310492 RH |
89 | UWORD magic; |
90 | ||
91 | pre_seq_barrier (smodel); | |
92 | magic = protect_start (mptr); | |
93 | ||
94 | oldval = *mptr; | |
95 | *mptr = __GCC_ATOMIC_TEST_AND_SET_TRUEVAL; | |
96 | ||
97 | protect_end (mptr, magic); | |
98 | post_seq_barrier (smodel); | |
99 | ||
91734423 | 100 | return oldval != 0; |
48310492 RH |
101 | } |
102 | ||
103 | #define DONE 1 | |
104 | #endif /* N == 1 */ | |
105 | ||
106 | ||
107 | #if !DONE | |
108 | bool | |
109 | SIZE(libat_test_and_set) (UTYPE *mptr, int smodel UNUSED) | |
110 | { | |
111 | return libat_test_and_set_1 ((U_1 *)mptr, smodel); | |
112 | } | |
113 | #endif | |
114 | ||
115 | EXPORT_ALIAS (SIZE(test_and_set)); |