source: trunk/sys/libgomp/bar.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, 2008, 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 is the default implementation of a barrier synchronization mechanism
26   for libgomp.  This type is private to the library.  Note that we rely on
27   being able to adjust the barrier count while threads are blocked, so the
28   POSIX pthread_barrier_t won't work.  */
29
30#include <gomp/libgomp.h>
31
32
33void
34gomp_barrier_init (gomp_barrier_t *bar, unsigned count)
35{
36  gomp_mutex_init (&bar->mutex1);
37#ifndef HAVE_SYNC_BUILTINS
38  gomp_mutex_init (&bar->mutex2);
39#endif
40  gomp_sem_init (&bar->sem1, 0);
41  gomp_sem_init (&bar->sem2, 0);
42  bar->total = count;
43  bar->arrived = 0;
44  bar->generation = 0;
45}
46
47void
48gomp_barrier_destroy (gomp_barrier_t *bar)
49{
50  /* Before destroying, make sure all threads have left the barrier.  */
51  gomp_mutex_lock (&bar->mutex1);
52  gomp_mutex_unlock (&bar->mutex1);
53
54  gomp_mutex_destroy (&bar->mutex1);
55#ifndef HAVE_SYNC_BUILTINS
56  gomp_mutex_destroy (&bar->mutex2);
57#endif
58  gomp_sem_destroy (&bar->sem1);
59  gomp_sem_destroy (&bar->sem2);
60}
61
62void
63gomp_barrier_reinit (gomp_barrier_t *bar, unsigned count)
64{
65  gomp_mutex_lock (&bar->mutex1);
66  bar->total = count;
67  gomp_mutex_unlock (&bar->mutex1);
68}
69
70void
71gomp_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)
72{
73  unsigned int n;
74
75  if (state & 1)
76    {
77      n = --bar->arrived;
78      if (n > 0)
79        {
80          do
81            gomp_sem_post (&bar->sem1);
82          while (--n != 0);
83          gomp_sem_wait (&bar->sem2);
84        }
85      gomp_mutex_unlock (&bar->mutex1);
86    }
87  else
88    {
89      gomp_mutex_unlock (&bar->mutex1);
90      gomp_sem_wait (&bar->sem1);
91
92#ifdef HAVE_SYNC_BUILTINS
93      n = __sync_add_and_fetch (&bar->arrived, -1);
94#else
95      gomp_mutex_lock (&bar->mutex2);
96      n = --bar->arrived;
97      gomp_mutex_unlock (&bar->mutex2);
98#endif
99
100      if (n == 0)
101        gomp_sem_post (&bar->sem2);
102    }
103}
104
105void
106gomp_barrier_wait (gomp_barrier_t *barrier)
107{
108  gomp_barrier_wait_end (barrier, gomp_barrier_wait_start (barrier));
109}
110
111void
112gomp_team_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)
113{
114  unsigned int n;
115
116  if (state & 1)
117    {
118      n = --bar->arrived;
119      struct gomp_thread *thr = gomp_thread ();
120      struct gomp_team *team = thr->ts.team;
121
122      if (team->task_count)
123        {
124          gomp_barrier_handle_tasks (state);
125          if (n > 0)
126            gomp_sem_wait (&bar->sem2);
127          gomp_mutex_unlock (&bar->mutex1);
128          return;
129        }
130
131      bar->generation = state + 3;
132      if (n > 0)
133        {
134          do
135            gomp_sem_post (&bar->sem1);
136          while (--n != 0);
137          gomp_sem_wait (&bar->sem2);
138        }
139      gomp_mutex_unlock (&bar->mutex1);
140    }
141  else
142    {
143      gomp_mutex_unlock (&bar->mutex1);
144      do
145        {
146          gomp_sem_wait (&bar->sem1);
147          if (bar->generation & 1)
148            gomp_barrier_handle_tasks (state);
149        }
150      while (bar->generation != state + 4);
151
152#ifdef HAVE_SYNC_BUILTINS
153      n = __sync_add_and_fetch (&bar->arrived, -1);
154#else
155      gomp_mutex_lock (&bar->mutex2);
156      n = --bar->arrived;
157      gomp_mutex_unlock (&bar->mutex2);
158#endif
159
160      if (n == 0)
161        gomp_sem_post (&bar->sem2);
162    }
163}
164
165void
166gomp_team_barrier_wait (gomp_barrier_t *barrier)
167{
168  gomp_team_barrier_wait_end (barrier, gomp_barrier_wait_start (barrier));
169}
170
171void
172gomp_team_barrier_wake (gomp_barrier_t *bar, int count)
173{
174  if (count == 0)
175    count = bar->total - 1;
176  while (count-- > 0)
177    gomp_sem_post (&bar->sem1);
178}
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