300 lines
7.1 KiB
C
300 lines
7.1 KiB
C
/* Copyright (C) 2005-2022 Free Software Foundation, Inc.
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Contributed by Richard Henderson <rth@redhat.com>.
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This file is part of the GNU Offloading and Multi Processing Library
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(libgomp).
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Libgomp is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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/* This is the default implementation of a barrier synchronization mechanism
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for libgomp. This type is private to the library. Note that we rely on
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being able to adjust the barrier count while threads are blocked, so the
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POSIX pthread_barrier_t won't work. */
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#include "libgomp.h"
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void
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gomp_barrier_init (gomp_barrier_t *bar, unsigned count)
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{
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gomp_mutex_init (&bar->mutex1);
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#ifndef HAVE_SYNC_BUILTINS
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gomp_mutex_init (&bar->mutex2);
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#endif
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gomp_sem_init (&bar->sem1, 0);
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gomp_sem_init (&bar->sem2, 0);
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bar->total = count;
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bar->arrived = 0;
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bar->generation = 0;
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bar->cancellable = false;
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}
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void
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gomp_barrier_destroy (gomp_barrier_t *bar)
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{
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/* Before destroying, make sure all threads have left the barrier. */
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gomp_mutex_lock (&bar->mutex1);
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gomp_mutex_unlock (&bar->mutex1);
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gomp_mutex_destroy (&bar->mutex1);
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#ifndef HAVE_SYNC_BUILTINS
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gomp_mutex_destroy (&bar->mutex2);
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#endif
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gomp_sem_destroy (&bar->sem1);
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gomp_sem_destroy (&bar->sem2);
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}
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void
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gomp_barrier_reinit (gomp_barrier_t *bar, unsigned count)
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{
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gomp_mutex_lock (&bar->mutex1);
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bar->total = count;
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gomp_mutex_unlock (&bar->mutex1);
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}
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void
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gomp_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)
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{
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unsigned int n;
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if (state & BAR_WAS_LAST)
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{
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n = --bar->arrived;
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if (n > 0)
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{
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do
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gomp_sem_post (&bar->sem1);
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while (--n != 0);
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gomp_sem_wait (&bar->sem2);
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}
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gomp_mutex_unlock (&bar->mutex1);
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}
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else
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{
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gomp_mutex_unlock (&bar->mutex1);
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gomp_sem_wait (&bar->sem1);
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#ifdef HAVE_SYNC_BUILTINS
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n = __sync_add_and_fetch (&bar->arrived, -1);
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#else
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gomp_mutex_lock (&bar->mutex2);
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n = --bar->arrived;
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gomp_mutex_unlock (&bar->mutex2);
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#endif
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if (n == 0)
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gomp_sem_post (&bar->sem2);
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}
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}
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void
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gomp_barrier_wait (gomp_barrier_t *barrier)
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{
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gomp_barrier_wait_end (barrier, gomp_barrier_wait_start (barrier));
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}
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void
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gomp_team_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)
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{
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unsigned int n;
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state &= ~BAR_CANCELLED;
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if (state & BAR_WAS_LAST)
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{
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n = --bar->arrived;
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struct gomp_thread *thr = gomp_thread ();
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struct gomp_team *team = thr->ts.team;
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team->work_share_cancelled = 0;
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if (team->task_count)
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{
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gomp_barrier_handle_tasks (state);
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if (n > 0)
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gomp_sem_wait (&bar->sem2);
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gomp_mutex_unlock (&bar->mutex1);
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return;
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}
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bar->generation = state + BAR_INCR - BAR_WAS_LAST;
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if (n > 0)
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{
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do
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gomp_sem_post (&bar->sem1);
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while (--n != 0);
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gomp_sem_wait (&bar->sem2);
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}
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gomp_mutex_unlock (&bar->mutex1);
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}
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else
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{
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gomp_mutex_unlock (&bar->mutex1);
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int gen;
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do
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{
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gomp_sem_wait (&bar->sem1);
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gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE);
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if (gen & BAR_TASK_PENDING)
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{
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gomp_barrier_handle_tasks (state);
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gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE);
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}
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}
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while (gen != state + BAR_INCR);
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#ifdef HAVE_SYNC_BUILTINS
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n = __sync_add_and_fetch (&bar->arrived, -1);
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#else
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gomp_mutex_lock (&bar->mutex2);
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n = --bar->arrived;
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gomp_mutex_unlock (&bar->mutex2);
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#endif
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if (n == 0)
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gomp_sem_post (&bar->sem2);
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}
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}
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bool
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gomp_team_barrier_wait_cancel_end (gomp_barrier_t *bar,
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gomp_barrier_state_t state)
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{
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unsigned int n;
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if (state & BAR_WAS_LAST)
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{
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bar->cancellable = false;
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n = --bar->arrived;
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struct gomp_thread *thr = gomp_thread ();
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struct gomp_team *team = thr->ts.team;
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team->work_share_cancelled = 0;
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if (team->task_count)
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{
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gomp_barrier_handle_tasks (state);
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if (n > 0)
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gomp_sem_wait (&bar->sem2);
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gomp_mutex_unlock (&bar->mutex1);
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return false;
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}
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bar->generation = state + BAR_INCR - BAR_WAS_LAST;
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if (n > 0)
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{
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do
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gomp_sem_post (&bar->sem1);
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while (--n != 0);
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gomp_sem_wait (&bar->sem2);
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}
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gomp_mutex_unlock (&bar->mutex1);
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}
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else
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{
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if (state & BAR_CANCELLED)
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{
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gomp_mutex_unlock (&bar->mutex1);
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return true;
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}
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bar->cancellable = true;
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gomp_mutex_unlock (&bar->mutex1);
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int gen;
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do
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{
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gomp_sem_wait (&bar->sem1);
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gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE);
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if (gen & BAR_CANCELLED)
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break;
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if (gen & BAR_TASK_PENDING)
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{
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gomp_barrier_handle_tasks (state);
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gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE);
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if (gen & BAR_CANCELLED)
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break;
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}
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}
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while (gen != state + BAR_INCR);
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#ifdef HAVE_SYNC_BUILTINS
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n = __sync_add_and_fetch (&bar->arrived, -1);
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#else
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gomp_mutex_lock (&bar->mutex2);
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n = --bar->arrived;
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gomp_mutex_unlock (&bar->mutex2);
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#endif
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if (n == 0)
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gomp_sem_post (&bar->sem2);
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if (gen & BAR_CANCELLED)
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return true;
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}
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return false;
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}
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void
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gomp_team_barrier_wait (gomp_barrier_t *barrier)
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{
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gomp_team_barrier_wait_end (barrier, gomp_barrier_wait_start (barrier));
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}
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void
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gomp_team_barrier_wake (gomp_barrier_t *bar, int count)
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{
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if (count == 0)
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count = bar->total - 1;
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while (count-- > 0)
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gomp_sem_post (&bar->sem1);
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}
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bool
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gomp_team_barrier_wait_cancel (gomp_barrier_t *bar)
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{
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gomp_barrier_state_t state = gomp_barrier_wait_cancel_start (bar);
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return gomp_team_barrier_wait_cancel_end (bar, state);
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}
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void
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gomp_team_barrier_cancel (struct gomp_team *team)
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{
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if (team->barrier.generation & BAR_CANCELLED)
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return;
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gomp_mutex_lock (&team->barrier.mutex1);
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gomp_mutex_lock (&team->task_lock);
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if (team->barrier.generation & BAR_CANCELLED)
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{
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gomp_mutex_unlock (&team->task_lock);
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gomp_mutex_unlock (&team->barrier.mutex1);
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return;
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}
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team->barrier.generation |= BAR_CANCELLED;
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gomp_mutex_unlock (&team->task_lock);
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if (team->barrier.cancellable)
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{
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int n = team->barrier.arrived;
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if (n > 0)
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{
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do
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gomp_sem_post (&team->barrier.sem1);
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while (--n != 0);
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gomp_sem_wait (&team->barrier.sem2);
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}
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team->barrier.cancellable = false;
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}
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gomp_mutex_unlock (&team->barrier.mutex1);
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}
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