4c5ba8d0db
PR libgomp/55411 * team.c (gomp_free_thread): Decrease gomp_managed_threads if pool had any threads_used. From-SVN: r193706
574 lines
16 KiB
C
574 lines
16 KiB
C
/* Copyright (C) 2005, 2006, 2007, 2008, 2009, 2011, 2012
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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 OpenMP Library (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 file handles the maintainence of threads in response to team
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creation and termination. */
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#include "libgomp.h"
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#include <stdlib.h>
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#include <string.h>
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/* This attribute contains PTHREAD_CREATE_DETACHED. */
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pthread_attr_t gomp_thread_attr;
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/* This key is for the thread destructor. */
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pthread_key_t gomp_thread_destructor;
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/* This is the libgomp per-thread data structure. */
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#ifdef HAVE_TLS
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__thread struct gomp_thread gomp_tls_data;
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#else
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pthread_key_t gomp_tls_key;
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#endif
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/* This structure is used to communicate across pthread_create. */
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struct gomp_thread_start_data
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{
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void (*fn) (void *);
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void *fn_data;
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struct gomp_team_state ts;
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struct gomp_task *task;
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struct gomp_thread_pool *thread_pool;
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bool nested;
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};
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/* This function is a pthread_create entry point. This contains the idle
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loop in which a thread waits to be called up to become part of a team. */
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static void *
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gomp_thread_start (void *xdata)
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{
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struct gomp_thread_start_data *data = xdata;
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struct gomp_thread *thr;
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struct gomp_thread_pool *pool;
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void (*local_fn) (void *);
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void *local_data;
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#ifdef HAVE_TLS
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thr = &gomp_tls_data;
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#else
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struct gomp_thread local_thr;
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thr = &local_thr;
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pthread_setspecific (gomp_tls_key, thr);
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#endif
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gomp_sem_init (&thr->release, 0);
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/* Extract what we need from data. */
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local_fn = data->fn;
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local_data = data->fn_data;
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thr->thread_pool = data->thread_pool;
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thr->ts = data->ts;
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thr->task = data->task;
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thr->ts.team->ordered_release[thr->ts.team_id] = &thr->release;
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/* Make thread pool local. */
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pool = thr->thread_pool;
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if (data->nested)
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{
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struct gomp_team *team = thr->ts.team;
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struct gomp_task *task = thr->task;
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gomp_barrier_wait (&team->barrier);
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local_fn (local_data);
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gomp_team_barrier_wait (&team->barrier);
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gomp_finish_task (task);
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gomp_barrier_wait_last (&team->barrier);
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}
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else
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{
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pool->threads[thr->ts.team_id] = thr;
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gomp_barrier_wait (&pool->threads_dock);
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do
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{
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struct gomp_team *team = thr->ts.team;
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struct gomp_task *task = thr->task;
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local_fn (local_data);
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gomp_team_barrier_wait (&team->barrier);
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gomp_finish_task (task);
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gomp_barrier_wait (&pool->threads_dock);
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local_fn = thr->fn;
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local_data = thr->data;
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thr->fn = NULL;
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}
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while (local_fn);
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}
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gomp_sem_destroy (&thr->release);
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return NULL;
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}
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/* Create a new team data structure. */
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struct gomp_team *
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gomp_new_team (unsigned nthreads)
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{
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struct gomp_team *team;
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size_t size;
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int i;
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size = sizeof (*team) + nthreads * (sizeof (team->ordered_release[0])
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+ sizeof (team->implicit_task[0]));
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team = gomp_malloc (size);
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team->work_share_chunk = 8;
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#ifdef HAVE_SYNC_BUILTINS
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team->single_count = 0;
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#else
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gomp_mutex_init (&team->work_share_list_free_lock);
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#endif
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gomp_init_work_share (&team->work_shares[0], false, nthreads);
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team->work_shares[0].next_alloc = NULL;
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team->work_share_list_free = NULL;
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team->work_share_list_alloc = &team->work_shares[1];
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for (i = 1; i < 7; i++)
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team->work_shares[i].next_free = &team->work_shares[i + 1];
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team->work_shares[i].next_free = NULL;
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team->nthreads = nthreads;
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gomp_barrier_init (&team->barrier, nthreads);
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gomp_sem_init (&team->master_release, 0);
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team->ordered_release = (void *) &team->implicit_task[nthreads];
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team->ordered_release[0] = &team->master_release;
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gomp_mutex_init (&team->task_lock);
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team->task_queue = NULL;
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team->task_count = 0;
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team->task_running_count = 0;
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return team;
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}
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/* Free a team data structure. */
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static void
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free_team (struct gomp_team *team)
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{
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gomp_barrier_destroy (&team->barrier);
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gomp_mutex_destroy (&team->task_lock);
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free (team);
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}
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/* Allocate and initialize a thread pool. */
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static struct gomp_thread_pool *gomp_new_thread_pool (void)
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{
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struct gomp_thread_pool *pool
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= gomp_malloc (sizeof(struct gomp_thread_pool));
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pool->threads = NULL;
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pool->threads_size = 0;
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pool->threads_used = 0;
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pool->last_team = NULL;
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return pool;
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}
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static void
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gomp_free_pool_helper (void *thread_pool)
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{
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struct gomp_thread_pool *pool
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= (struct gomp_thread_pool *) thread_pool;
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gomp_barrier_wait_last (&pool->threads_dock);
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gomp_sem_destroy (&gomp_thread ()->release);
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pthread_exit (NULL);
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}
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/* Free a thread pool and release its threads. */
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static void
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gomp_free_thread (void *arg __attribute__((unused)))
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{
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struct gomp_thread *thr = gomp_thread ();
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struct gomp_thread_pool *pool = thr->thread_pool;
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if (pool)
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{
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if (pool->threads_used > 0)
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{
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int i;
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for (i = 1; i < pool->threads_used; i++)
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{
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struct gomp_thread *nthr = pool->threads[i];
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nthr->fn = gomp_free_pool_helper;
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nthr->data = pool;
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}
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/* This barrier undocks threads docked on pool->threads_dock. */
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gomp_barrier_wait (&pool->threads_dock);
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/* And this waits till all threads have called gomp_barrier_wait_last
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in gomp_free_pool_helper. */
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gomp_barrier_wait (&pool->threads_dock);
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/* Now it is safe to destroy the barrier and free the pool. */
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gomp_barrier_destroy (&pool->threads_dock);
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#ifdef HAVE_SYNC_BUILTINS
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__sync_fetch_and_add (&gomp_managed_threads,
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1L - pool->threads_used);
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#else
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gomp_mutex_lock (&gomp_remaining_threads_lock);
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gomp_managed_threads -= pool->threads_used - 1L;
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gomp_mutex_unlock (&gomp_remaining_threads_lock);
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#endif
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}
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free (pool->threads);
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if (pool->last_team)
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free_team (pool->last_team);
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free (pool);
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thr->thread_pool = NULL;
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}
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if (thr->task != NULL)
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{
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struct gomp_task *task = thr->task;
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gomp_end_task ();
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free (task);
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}
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}
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/* Launch a team. */
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void
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gomp_team_start (void (*fn) (void *), void *data, unsigned nthreads,
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struct gomp_team *team)
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{
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struct gomp_thread_start_data *start_data;
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struct gomp_thread *thr, *nthr;
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struct gomp_task *task;
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struct gomp_task_icv *icv;
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bool nested;
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struct gomp_thread_pool *pool;
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unsigned i, n, old_threads_used = 0;
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pthread_attr_t thread_attr, *attr;
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unsigned long nthreads_var;
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thr = gomp_thread ();
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nested = thr->ts.team != NULL;
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if (__builtin_expect (thr->thread_pool == NULL, 0))
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{
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thr->thread_pool = gomp_new_thread_pool ();
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pthread_setspecific (gomp_thread_destructor, thr);
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}
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pool = thr->thread_pool;
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task = thr->task;
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icv = task ? &task->icv : &gomp_global_icv;
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/* Always save the previous state, even if this isn't a nested team.
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In particular, we should save any work share state from an outer
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orphaned work share construct. */
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team->prev_ts = thr->ts;
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thr->ts.team = team;
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thr->ts.team_id = 0;
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++thr->ts.level;
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if (nthreads > 1)
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++thr->ts.active_level;
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thr->ts.work_share = &team->work_shares[0];
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thr->ts.last_work_share = NULL;
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#ifdef HAVE_SYNC_BUILTINS
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thr->ts.single_count = 0;
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#endif
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thr->ts.static_trip = 0;
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thr->task = &team->implicit_task[0];
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nthreads_var = icv->nthreads_var;
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if (__builtin_expect (gomp_nthreads_var_list != NULL, 0)
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&& thr->ts.level < gomp_nthreads_var_list_len)
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nthreads_var = gomp_nthreads_var_list[thr->ts.level];
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gomp_init_task (thr->task, task, icv);
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team->implicit_task[0].icv.nthreads_var = nthreads_var;
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if (nthreads == 1)
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return;
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i = 1;
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/* We only allow the reuse of idle threads for non-nested PARALLEL
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regions. This appears to be implied by the semantics of
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threadprivate variables, but perhaps that's reading too much into
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things. Certainly it does prevent any locking problems, since
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only the initial program thread will modify gomp_threads. */
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if (!nested)
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{
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old_threads_used = pool->threads_used;
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if (nthreads <= old_threads_used)
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n = nthreads;
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else if (old_threads_used == 0)
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{
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n = 0;
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gomp_barrier_init (&pool->threads_dock, nthreads);
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}
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else
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{
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n = old_threads_used;
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/* Increase the barrier threshold to make sure all new
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threads arrive before the team is released. */
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gomp_barrier_reinit (&pool->threads_dock, nthreads);
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}
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/* Not true yet, but soon will be. We're going to release all
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threads from the dock, and those that aren't part of the
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team will exit. */
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pool->threads_used = nthreads;
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/* Release existing idle threads. */
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for (; i < n; ++i)
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{
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nthr = pool->threads[i];
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nthr->ts.team = team;
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nthr->ts.work_share = &team->work_shares[0];
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nthr->ts.last_work_share = NULL;
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nthr->ts.team_id = i;
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nthr->ts.level = team->prev_ts.level + 1;
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nthr->ts.active_level = thr->ts.active_level;
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#ifdef HAVE_SYNC_BUILTINS
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nthr->ts.single_count = 0;
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#endif
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nthr->ts.static_trip = 0;
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nthr->task = &team->implicit_task[i];
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gomp_init_task (nthr->task, task, icv);
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team->implicit_task[i].icv.nthreads_var = nthreads_var;
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nthr->fn = fn;
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nthr->data = data;
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team->ordered_release[i] = &nthr->release;
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}
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if (i == nthreads)
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goto do_release;
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/* If necessary, expand the size of the gomp_threads array. It is
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expected that changes in the number of threads are rare, thus we
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make no effort to expand gomp_threads_size geometrically. */
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if (nthreads >= pool->threads_size)
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{
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pool->threads_size = nthreads + 1;
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pool->threads
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= gomp_realloc (pool->threads,
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pool->threads_size
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* sizeof (struct gomp_thread_data *));
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}
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}
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if (__builtin_expect (nthreads > old_threads_used, 0))
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{
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long diff = (long) nthreads - (long) old_threads_used;
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if (old_threads_used == 0)
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--diff;
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#ifdef HAVE_SYNC_BUILTINS
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__sync_fetch_and_add (&gomp_managed_threads, diff);
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#else
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gomp_mutex_lock (&gomp_remaining_threads_lock);
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gomp_managed_threads += diff;
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gomp_mutex_unlock (&gomp_remaining_threads_lock);
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#endif
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}
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attr = &gomp_thread_attr;
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if (__builtin_expect (gomp_cpu_affinity != NULL, 0))
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{
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size_t stacksize;
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pthread_attr_init (&thread_attr);
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pthread_attr_setdetachstate (&thread_attr, PTHREAD_CREATE_DETACHED);
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if (! pthread_attr_getstacksize (&gomp_thread_attr, &stacksize))
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pthread_attr_setstacksize (&thread_attr, stacksize);
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attr = &thread_attr;
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}
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start_data = gomp_alloca (sizeof (struct gomp_thread_start_data)
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* (nthreads-i));
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/* Launch new threads. */
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for (; i < nthreads; ++i, ++start_data)
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{
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pthread_t pt;
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int err;
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start_data->fn = fn;
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start_data->fn_data = data;
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start_data->ts.team = team;
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start_data->ts.work_share = &team->work_shares[0];
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start_data->ts.last_work_share = NULL;
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start_data->ts.team_id = i;
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start_data->ts.level = team->prev_ts.level + 1;
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start_data->ts.active_level = thr->ts.active_level;
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#ifdef HAVE_SYNC_BUILTINS
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start_data->ts.single_count = 0;
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#endif
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start_data->ts.static_trip = 0;
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start_data->task = &team->implicit_task[i];
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gomp_init_task (start_data->task, task, icv);
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team->implicit_task[i].icv.nthreads_var = nthreads_var;
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start_data->thread_pool = pool;
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start_data->nested = nested;
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if (gomp_cpu_affinity != NULL)
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gomp_init_thread_affinity (attr);
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err = pthread_create (&pt, attr, gomp_thread_start, start_data);
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if (err != 0)
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gomp_fatal ("Thread creation failed: %s", strerror (err));
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}
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if (__builtin_expect (gomp_cpu_affinity != NULL, 0))
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pthread_attr_destroy (&thread_attr);
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do_release:
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gomp_barrier_wait (nested ? &team->barrier : &pool->threads_dock);
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/* Decrease the barrier threshold to match the number of threads
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that should arrive back at the end of this team. The extra
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threads should be exiting. Note that we arrange for this test
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to never be true for nested teams. */
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if (__builtin_expect (nthreads < old_threads_used, 0))
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{
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long diff = (long) nthreads - (long) old_threads_used;
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gomp_barrier_reinit (&pool->threads_dock, nthreads);
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#ifdef HAVE_SYNC_BUILTINS
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__sync_fetch_and_add (&gomp_managed_threads, diff);
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#else
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gomp_mutex_lock (&gomp_remaining_threads_lock);
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gomp_managed_threads += diff;
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gomp_mutex_unlock (&gomp_remaining_threads_lock);
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#endif
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}
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}
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/* Terminate the current team. This is only to be called by the master
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thread. We assume that we must wait for the other threads. */
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void
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gomp_team_end (void)
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{
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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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/* This barrier handles all pending explicit threads. */
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gomp_team_barrier_wait (&team->barrier);
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gomp_fini_work_share (thr->ts.work_share);
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gomp_end_task ();
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thr->ts = team->prev_ts;
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if (__builtin_expect (thr->ts.team != NULL, 0))
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{
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#ifdef HAVE_SYNC_BUILTINS
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__sync_fetch_and_add (&gomp_managed_threads, 1L - team->nthreads);
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#else
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gomp_mutex_lock (&gomp_remaining_threads_lock);
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gomp_managed_threads -= team->nthreads - 1L;
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gomp_mutex_unlock (&gomp_remaining_threads_lock);
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#endif
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/* This barrier has gomp_barrier_wait_last counterparts
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and ensures the team can be safely destroyed. */
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gomp_barrier_wait (&team->barrier);
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}
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if (__builtin_expect (team->work_shares[0].next_alloc != NULL, 0))
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{
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struct gomp_work_share *ws = team->work_shares[0].next_alloc;
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do
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{
|
|
struct gomp_work_share *next_ws = ws->next_alloc;
|
|
free (ws);
|
|
ws = next_ws;
|
|
}
|
|
while (ws != NULL);
|
|
}
|
|
gomp_sem_destroy (&team->master_release);
|
|
#ifndef HAVE_SYNC_BUILTINS
|
|
gomp_mutex_destroy (&team->work_share_list_free_lock);
|
|
#endif
|
|
|
|
if (__builtin_expect (thr->ts.team != NULL, 0)
|
|
|| __builtin_expect (team->nthreads == 1, 0))
|
|
free_team (team);
|
|
else
|
|
{
|
|
struct gomp_thread_pool *pool = thr->thread_pool;
|
|
if (pool->last_team)
|
|
free_team (pool->last_team);
|
|
pool->last_team = team;
|
|
}
|
|
}
|
|
|
|
|
|
/* Constructors for this file. */
|
|
|
|
static void __attribute__((constructor))
|
|
initialize_team (void)
|
|
{
|
|
struct gomp_thread *thr;
|
|
|
|
#ifndef HAVE_TLS
|
|
static struct gomp_thread initial_thread_tls_data;
|
|
|
|
pthread_key_create (&gomp_tls_key, NULL);
|
|
pthread_setspecific (gomp_tls_key, &initial_thread_tls_data);
|
|
#endif
|
|
|
|
if (pthread_key_create (&gomp_thread_destructor, gomp_free_thread) != 0)
|
|
gomp_fatal ("could not create thread pool destructor.");
|
|
|
|
#ifdef HAVE_TLS
|
|
thr = &gomp_tls_data;
|
|
#else
|
|
thr = &initial_thread_tls_data;
|
|
#endif
|
|
gomp_sem_init (&thr->release, 0);
|
|
}
|
|
|
|
static void __attribute__((destructor))
|
|
team_destructor (void)
|
|
{
|
|
/* Without this dlclose on libgomp could lead to subsequent
|
|
crashes. */
|
|
pthread_key_delete (gomp_thread_destructor);
|
|
}
|
|
|
|
struct gomp_task_icv *
|
|
gomp_new_icv (void)
|
|
{
|
|
struct gomp_thread *thr = gomp_thread ();
|
|
struct gomp_task *task = gomp_malloc (sizeof (struct gomp_task));
|
|
gomp_init_task (task, NULL, &gomp_global_icv);
|
|
thr->task = task;
|
|
pthread_setspecific (gomp_thread_destructor, thr);
|
|
return &task->icv;
|
|
}
|