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 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 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 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 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 108 gomp_barrier_wait (gomp_barrier_t *barrier) 109 { 110 gomp_barrier_wait_end (barrier, gomp_barrier_wait_start (barrier)); 111 } 112