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
34static gomp_mutex_t default_lock;
35
36void
37GOMP_critical_start (void)
38{
39  gomp_mutex_lock (&default_lock);
40}
41
42void
43GOMP_critical_end (void)
44{
45  gomp_mutex_unlock (&default_lock);
46}
47
48#ifndef HAVE_SYNC_BUILTINS
49static gomp_mutex_t create_lock_lock;
50#endif
51
52void
53GOMP_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, NULL, nlock);
76	  if (plock != NULL)
77	    {
78	      gomp_mutex_destroy (nlock);
79	      free (nlock);
80	    }
81	  else
82	    plock = nlock;
83#else
84	  gomp_mutex_lock (&create_lock_lock);
85	  plock = *pptr;
86	  if (plock == NULL)
87	    {
88	      plock = gomp_malloc (sizeof (gomp_mutex_t));
89	      gomp_mutex_init (plock);
90	      __sync_synchronize ();
91	      *pptr = plock;
92	    }
93	  gomp_mutex_unlock (&create_lock_lock);
94#endif
95	}
96    }
97
98  gomp_mutex_lock (plock);
99}
100
101void
102GOMP_critical_name_end (void **pptr)
103{
104  gomp_mutex_t *plock;
105
106  /* If a mutex fits within the space for a pointer, and is zero initialized,
107     then use the pointer space directly.  */
108  if (GOMP_MUTEX_INIT_0
109      && sizeof (gomp_mutex_t) <= sizeof (void *)
110      && __alignof (gomp_mutex_t) <= sizeof (void *))
111    plock = (gomp_mutex_t *)pptr;
112  else
113    plock = *pptr;
114
115  gomp_mutex_unlock (plock);
116}
117
118/* This mutex is used when atomic operations don't exist for the target
119   in the mode requested.  The result is not globally atomic, but works so
120   long as all parallel references are within #pragma omp atomic directives.
121   According to responses received from omp@openmp.org, appears to be within
122   spec.  Which makes sense, since that's how several other compilers
123   handle this situation as well.  */
124
125static gomp_mutex_t atomic_lock;
126
127void
128GOMP_atomic_start (void)
129{
130  gomp_mutex_lock (&atomic_lock);
131}
132
133void
134GOMP_atomic_end (void)
135{
136  gomp_mutex_unlock (&atomic_lock);
137}
138
139#if !GOMP_MUTEX_INIT_0
140static void __attribute__((constructor))
141initialize_critical (void)
142{
143  gomp_mutex_init (&default_lock);
144  gomp_mutex_init (&atomic_lock);
145#ifndef HAVE_SYNC_BUILTINS
146  gomp_mutex_init (&create_lock_lock);
147#endif
148}
149#endif
150