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1 | /* Copyright (C) 2005 Free Software Foundation, Inc. |
2 | Contributed by Richard Henderson <rth@redhat.com>. | |
3 | ||
4 | This file is part of the GNU OpenMP Library (libgomp). | |
5 | ||
6 | Libgomp is free software; you can redistribute it and/or modify it | |
7 | under the terms of the GNU Lesser General Public License as published by | |
8 | the Free Software Foundation; either version 2.1 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | Libgomp 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 Lesser General Public License for | |
14 | more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public License | |
17 | along with libgomp; see the file COPYING.LIB. If not, write to the | |
18 | Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, | |
19 | MA 02110-1301, USA. */ | |
20 | ||
21 | /* As a special exception, if you link this library with other files, some | |
22 | of which are compiled with GCC, to produce an executable, this library | |
23 | does not by itself cause the resulting executable to be covered by the | |
24 | GNU General Public License. This exception does not however invalidate | |
25 | any other reasons why the executable file might be covered by the GNU | |
26 | General Public License. */ | |
27 | ||
28 | /* This file handles the CRITICAL construct. */ | |
29 | ||
30 | #include "libgomp.h" | |
31 | #include <stdlib.h> | |
32 | ||
33 | ||
34 | static gomp_mutex_t default_lock; | |
35 | ||
36 | void | |
37 | GOMP_critical_start (void) | |
38 | { | |
39 | gomp_mutex_lock (&default_lock); | |
40 | } | |
41 | ||
42 | void | |
43 | GOMP_critical_end (void) | |
44 | { | |
45 | gomp_mutex_unlock (&default_lock); | |
46 | } | |
47 | ||
48 | #ifndef HAVE_SYNC_BUILTINS | |
49 | static gomp_mutex_t create_lock_lock; | |
50 | #endif | |
51 | ||
52 | void | |
53 | GOMP_critical_name_start (void **pptr) | |
54 | { | |
55 | gomp_mutex_t *plock; | |
56 | ||
57 | /* If a mutex fits within the space for a pointer, and is zero initialized, | |
58 | then use the pointer space directly. */ | |
59 | if (GOMP_MUTEX_INIT_0 | |
60 | && sizeof (gomp_mutex_t) <= sizeof (void *) | |
61 | && __alignof (gomp_mutex_t) <= sizeof (void *)) | |
62 | plock = (gomp_mutex_t *)pptr; | |
63 | ||
64 | /* Otherwise we have to be prepared to malloc storage. */ | |
65 | else | |
66 | { | |
67 | plock = *pptr; | |
68 | ||
69 | if (plock == NULL) | |
70 | { | |
71 | #ifdef HAVE_SYNC_BUILTINS | |
72 | gomp_mutex_t *nlock = gomp_malloc (sizeof (gomp_mutex_t)); | |
73 | gomp_mutex_init (nlock); | |
74 | ||
75 | plock = __sync_val_compare_and_swap (pptr, plock, nlock); | |
76 | if (plock != nlock) | |
77 | { | |
78 | gomp_mutex_destroy (nlock); | |
79 | free (nlock); | |
80 | } | |
81 | #else | |
82 | gomp_mutex_lock (&create_lock_lock); | |
83 | plock = *pptr; | |
84 | if (plock == NULL) | |
85 | { | |
86 | plock = gomp_malloc (sizeof (gomp_mutex_t)); | |
87 | gomp_mutex_init (plock); | |
88 | __sync_synchronize (); | |
89 | *pptr = plock; | |
90 | } | |
91 | gomp_mutex_unlock (&create_lock_lock); | |
92 | #endif | |
93 | } | |
94 | } | |
95 | ||
96 | gomp_mutex_lock (plock); | |
97 | } | |
98 | ||
99 | void | |
100 | GOMP_critical_name_end (void **pptr) | |
101 | { | |
102 | gomp_mutex_t *plock; | |
103 | ||
104 | /* If a mutex fits within the space for a pointer, and is zero initialized, | |
105 | then use the pointer space directly. */ | |
106 | if (GOMP_MUTEX_INIT_0 | |
107 | && sizeof (gomp_mutex_t) <= sizeof (void *) | |
108 | && __alignof (gomp_mutex_t) <= sizeof (void *)) | |
109 | plock = (gomp_mutex_t *)pptr; | |
110 | else | |
111 | plock = *pptr; | |
112 | ||
113 | gomp_mutex_unlock (plock); | |
114 | } | |
115 | ||
116 | /* This mutex is used when atomic operations don't exist for the target | |
117 | in the mode requested. The result is not globally atomic, but works so | |
118 | long as all parallel references are within #pragma omp atomic directives. | |
119 | According to responses received from omp@openmp.org, appears to be within | |
120 | spec. Which makes sense, since that's how several other compilers | |
121 | handle this situation as well. */ | |
122 | ||
123 | static gomp_mutex_t atomic_lock; | |
124 | ||
125 | void | |
126 | GOMP_atomic_start (void) | |
127 | { | |
128 | gomp_mutex_lock (&atomic_lock); | |
129 | } | |
130 | ||
131 | void | |
132 | GOMP_atomic_end (void) | |
133 | { | |
134 | gomp_mutex_unlock (&atomic_lock); | |
135 | } | |
136 | ||
137 | #if !GOMP_MUTEX_INIT_0 | |
138 | static void __attribute__((constructor)) | |
139 | initialize_critical (void) | |
140 | { | |
141 | gomp_mutex_init (&default_lock); | |
142 | gomp_mutex_init (&atomic_lock); | |
143 | #ifndef HAVE_SYNC_BUILTINS | |
144 | gomp_mutex_init (&create_lock_lock); | |
145 | #endif | |
146 | } | |
147 | #endif |