source: trunk/sys/libgomp/critical.c @ 1

Last change on this file since 1 was 1, checked in by alain, 5 years ago

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1/* Copyright (C) 2005, 2009 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 General Public License as published by
8   the Free Software Foundation; either version 3, or (at your option)
9   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 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/* This file handles the CRITICAL construct.  */
26
27#include <gomp/libgomp.h>
28#include <stdlib.h>
29
30
31static gomp_mutex_t default_lock;
32
33void
34GOMP_critical_start (void)
35{
36  gomp_mutex_lock (&default_lock);
37}
38
39void
40GOMP_critical_end (void)
41{
42  gomp_mutex_unlock (&default_lock);
43}
44
45#ifndef HAVE_SYNC_BUILTINS
46static gomp_mutex_t create_lock_lock;
47#endif
48
49void
50GOMP_critical_name_start (void **pptr)
51{
52  gomp_mutex_t *plock;
53
54  /* If a mutex fits within the space for a pointer, and is zero initialized,
55     then use the pointer space directly.  */
56  if (GOMP_MUTEX_INIT_0
57      && sizeof (gomp_mutex_t) <= sizeof (void *)
58      && __alignof (gomp_mutex_t) <= sizeof (void *))
59    plock = (gomp_mutex_t *)pptr;
60
61  /* Otherwise we have to be prepared to malloc storage.  */
62  else
63    {
64      plock = *pptr;
65
66      if (plock == NULL)
67        {
68#ifdef HAVE_SYNC_BUILTINS
69          gomp_mutex_t *nlock = gomp_malloc (sizeof (gomp_mutex_t));
70          gomp_mutex_init (nlock);
71
72          plock = __sync_val_compare_and_swap (pptr, NULL, nlock);
73          if (plock != NULL)
74            {
75              gomp_mutex_destroy (nlock);
76              free (nlock);
77            }
78          else
79            plock = nlock;
80#else
81          gomp_mutex_lock (&create_lock_lock);
82          plock = *pptr;
83          if (plock == NULL)
84            {
85              plock = gomp_malloc (sizeof (gomp_mutex_t));
86              gomp_mutex_init (plock);
87              __sync_synchronize ();
88              *pptr = plock;
89            }
90          gomp_mutex_unlock (&create_lock_lock);
91#endif
92        }
93    }
94
95  gomp_mutex_lock (plock);
96}
97
98void
99GOMP_critical_name_end (void **pptr)
100{
101  gomp_mutex_t *plock;
102
103  /* If a mutex fits within the space for a pointer, and is zero initialized,
104     then use the pointer space directly.  */
105  if (GOMP_MUTEX_INIT_0
106      && sizeof (gomp_mutex_t) <= sizeof (void *)
107      && __alignof (gomp_mutex_t) <= sizeof (void *))
108    plock = (gomp_mutex_t *)pptr;
109  else
110    plock = *pptr;
111
112  gomp_mutex_unlock (plock);
113}
114
115/* This mutex is used when atomic operations don't exist for the target
116   in the mode requested.  The result is not globally atomic, but works so
117   long as all parallel references are within #pragma omp atomic directives.
118   According to responses received from omp@openmp.org, appears to be within
119   spec.  Which makes sense, since that's how several other compilers
120   handle this situation as well.  */
121
122static gomp_mutex_t atomic_lock;
123
124void
125GOMP_atomic_start (void)
126{
127  gomp_mutex_lock (&atomic_lock);
128}
129
130void
131GOMP_atomic_end (void)
132{
133  gomp_mutex_unlock (&atomic_lock);
134}
135
136#if !GOMP_MUTEX_INIT_0
137void initialize_critical (void)
138{
139  gomp_mutex_init (&default_lock);
140  gomp_mutex_init (&atomic_lock);
141#ifndef HAVE_SYNC_BUILTINS
142  gomp_mutex_init (&create_lock_lock);
143#endif
144}
145#endif
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