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 is the default implementation of a barrier synchronization mechanism
29 for libgomp. This type is private to the library. Note that we rely on
30 being able to adjust the barrier count while threads are blocked, so the
31 POSIX pthread_barrier_t won't work. */
32
33 #include "libgomp.h"
34
35
36 void
gomp_barrier_init(gomp_barrier_t * bar,unsigned count)37 gomp_barrier_init (gomp_barrier_t *bar, unsigned count)
38 {
39 gomp_mutex_init (&bar->mutex1);
40 #ifndef HAVE_SYNC_BUILTINS
41 gomp_mutex_init (&bar->mutex2);
42 #endif
43 gomp_sem_init (&bar->sem1, 0);
44 gomp_sem_init (&bar->sem2, 0);
45 bar->total = count;
46 bar->arrived = 0;
47 }
48
49 void
gomp_barrier_destroy(gomp_barrier_t * bar)50 gomp_barrier_destroy (gomp_barrier_t *bar)
51 {
52 /* Before destroying, make sure all threads have left the barrier. */
53 gomp_mutex_lock (&bar->mutex1);
54 gomp_mutex_unlock (&bar->mutex1);
55
56 gomp_mutex_destroy (&bar->mutex1);
57 #ifndef HAVE_SYNC_BUILTINS
58 gomp_mutex_destroy (&bar->mutex2);
59 #endif
60 gomp_sem_destroy (&bar->sem1);
61 gomp_sem_destroy (&bar->sem2);
62 }
63
64 void
gomp_barrier_reinit(gomp_barrier_t * bar,unsigned count)65 gomp_barrier_reinit (gomp_barrier_t *bar, unsigned count)
66 {
67 gomp_mutex_lock (&bar->mutex1);
68 bar->total = count;
69 gomp_mutex_unlock (&bar->mutex1);
70 }
71
72 void
gomp_barrier_wait_end(gomp_barrier_t * bar,bool last)73 gomp_barrier_wait_end (gomp_barrier_t *bar, bool last)
74 {
75 unsigned int n;
76
77 if (last)
78 {
79 n = --bar->arrived;
80 if (n > 0)
81 {
82 do
83 gomp_sem_post (&bar->sem1);
84 while (--n != 0);
85 gomp_sem_wait (&bar->sem2);
86 }
87 gomp_mutex_unlock (&bar->mutex1);
88 }
89 else
90 {
91 gomp_mutex_unlock (&bar->mutex1);
92 gomp_sem_wait (&bar->sem1);
93
94 #ifdef HAVE_SYNC_BUILTINS
95 n = __sync_add_and_fetch (&bar->arrived, -1);
96 #else
97 gomp_mutex_lock (&bar->mutex2);
98 n = --bar->arrived;
99 gomp_mutex_unlock (&bar->mutex2);
100 #endif
101
102 if (n == 0)
103 gomp_sem_post (&bar->sem2);
104 }
105 }
106
107 void
gomp_barrier_wait(gomp_barrier_t * barrier)108 gomp_barrier_wait (gomp_barrier_t *barrier)
109 {
110 gomp_barrier_wait_end (barrier, gomp_barrier_wait_start (barrier));
111 }
112