-/* Copyright (C) 2005 Free Software Foundation, Inc.
+/* Copyright (C) 2005-2021 Free Software Foundation, Inc.
Contributed by Richard Henderson <rth@redhat.com>.
- This file is part of the GNU OpenMP Library (libgomp).
+ This file is part of the GNU Offloading and Multi Processing Library
+ (libgomp).
Libgomp is free software; you can redistribute it and/or modify it
- under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 2.1 of the License, or
- (at your option) any later version.
+ under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3, or (at your option)
+ any later version.
Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
- FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
+ FOR A PARTICULAR PURPOSE. See the GNU General Public License for
more details.
- You should have received a copy of the GNU Lesser General Public License
- along with libgomp; see the file COPYING.LIB. If not, write to the
- Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
- MA 02110-1301, USA. */
+ Under Section 7 of GPL version 3, you are granted additional
+ permissions described in the GCC Runtime Library Exception, version
+ 3.1, as published by the Free Software Foundation.
-/* As a special exception, if you link this library with other files, some
- of which are compiled with GCC, to produce an executable, this library
- does not by itself cause the resulting executable to be covered by the
- GNU General Public License. This exception does not however invalidate
- any other reasons why the executable file might be covered by the GNU
- General Public License. */
+ You should have received a copy of the GNU General Public License and
+ a copy of the GCC Runtime Library Exception along with this program;
+ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+ <http://www.gnu.org/licenses/>. */
/* This is a Linux specific implementation of a barrier synchronization
mechanism for libgomp. This type is private to the library. This
implementation uses atomic instructions and the futex syscall. */
-#include "libgomp.h"
-#include "futex.h"
#include <limits.h>
+#include "wait.h"
void
-gomp_barrier_wait_end (gomp_barrier_t *bar, bool last)
+gomp_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)
{
- if (last)
+ if (__builtin_expect (state & BAR_WAS_LAST, 0))
{
- bar->generation++;
- futex_wake (&bar->generation, INT_MAX);
+ /* Next time we'll be awaiting TOTAL threads again. */
+ bar->awaited = bar->total;
+ __atomic_store_n (&bar->generation, bar->generation + BAR_INCR,
+ MEMMODEL_RELEASE);
+ futex_wake ((int *) &bar->generation, INT_MAX);
}
else
{
- unsigned int generation = bar->generation;
+ do
+ do_wait ((int *) &bar->generation, state);
+ while (__atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE) == state);
+ }
+}
+
+void
+gomp_barrier_wait (gomp_barrier_t *bar)
+{
+ gomp_barrier_wait_end (bar, gomp_barrier_wait_start (bar));
+}
- gomp_mutex_unlock (&bar->mutex);
+/* Like gomp_barrier_wait, except that if the encountering thread
+ is not the last one to hit the barrier, it returns immediately.
+ The intended usage is that a thread which intends to gomp_barrier_destroy
+ this barrier calls gomp_barrier_wait, while all other threads
+ call gomp_barrier_wait_last. When gomp_barrier_wait returns,
+ the barrier can be safely destroyed. */
- do
- futex_wait (&bar->generation, generation);
- while (bar->generation == generation);
+void
+gomp_barrier_wait_last (gomp_barrier_t *bar)
+{
+ gomp_barrier_state_t state = gomp_barrier_wait_start (bar);
+ if (state & BAR_WAS_LAST)
+ gomp_barrier_wait_end (bar, state);
+}
+
+void
+gomp_team_barrier_wake (gomp_barrier_t *bar, int count)
+{
+ futex_wake ((int *) &bar->generation, count == 0 ? INT_MAX : count);
+}
+
+void
+gomp_team_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)
+{
+ unsigned int generation, gen;
+
+ if (__builtin_expect (state & BAR_WAS_LAST, 0))
+ {
+ /* Next time we'll be awaiting TOTAL threads again. */
+ struct gomp_thread *thr = gomp_thread ();
+ struct gomp_team *team = thr->ts.team;
+
+ bar->awaited = bar->total;
+ team->work_share_cancelled = 0;
+ if (__builtin_expect (team->task_count, 0))
+ {
+ gomp_barrier_handle_tasks (state);
+ state &= ~BAR_WAS_LAST;
+ }
+ else
+ {
+ state &= ~BAR_CANCELLED;
+ state += BAR_INCR - BAR_WAS_LAST;
+ __atomic_store_n (&bar->generation, state, MEMMODEL_RELEASE);
+ futex_wake ((int *) &bar->generation, INT_MAX);
+ return;
+ }
+ }
+
+ generation = state;
+ state &= ~BAR_CANCELLED;
+ do
+ {
+ do_wait ((int *) &bar->generation, generation);
+ gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE);
+ if (__builtin_expect (gen & BAR_TASK_PENDING, 0))
+ {
+ gomp_barrier_handle_tasks (state);
+ gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE);
+ }
+ generation |= gen & BAR_WAITING_FOR_TASK;
}
+ while (gen != state + BAR_INCR);
+}
+
+void
+gomp_team_barrier_wait (gomp_barrier_t *bar)
+{
+ gomp_team_barrier_wait_end (bar, gomp_barrier_wait_start (bar));
+}
+
+void
+gomp_team_barrier_wait_final (gomp_barrier_t *bar)
+{
+ gomp_barrier_state_t state = gomp_barrier_wait_final_start (bar);
+ if (__builtin_expect (state & BAR_WAS_LAST, 0))
+ bar->awaited_final = bar->total;
+ gomp_team_barrier_wait_end (bar, state);
+}
+
+bool
+gomp_team_barrier_wait_cancel_end (gomp_barrier_t *bar,
+ gomp_barrier_state_t state)
+{
+ unsigned int generation, gen;
+
+ if (__builtin_expect (state & BAR_WAS_LAST, 0))
+ {
+ /* Next time we'll be awaiting TOTAL threads again. */
+ /* BAR_CANCELLED should never be set in state here, because
+ cancellation means that at least one of the threads has been
+ cancelled, thus on a cancellable barrier we should never see
+ all threads to arrive. */
+ struct gomp_thread *thr = gomp_thread ();
+ struct gomp_team *team = thr->ts.team;
+
+ bar->awaited = bar->total;
+ team->work_share_cancelled = 0;
+ if (__builtin_expect (team->task_count, 0))
+ {
+ gomp_barrier_handle_tasks (state);
+ state &= ~BAR_WAS_LAST;
+ }
+ else
+ {
+ state += BAR_INCR - BAR_WAS_LAST;
+ __atomic_store_n (&bar->generation, state, MEMMODEL_RELEASE);
+ futex_wake ((int *) &bar->generation, INT_MAX);
+ return false;
+ }
+ }
+
+ if (__builtin_expect (state & BAR_CANCELLED, 0))
+ return true;
+
+ generation = state;
+ do
+ {
+ do_wait ((int *) &bar->generation, generation);
+ gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE);
+ if (__builtin_expect (gen & BAR_CANCELLED, 0))
+ return true;
+ if (__builtin_expect (gen & BAR_TASK_PENDING, 0))
+ {
+ gomp_barrier_handle_tasks (state);
+ gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE);
+ }
+ generation |= gen & BAR_WAITING_FOR_TASK;
+ }
+ while (gen != state + BAR_INCR);
+
+ return false;
+}
- if (__sync_add_and_fetch (&bar->arrived, -1) == 0)
- gomp_mutex_unlock (&bar->mutex);
+bool
+gomp_team_barrier_wait_cancel (gomp_barrier_t *bar)
+{
+ return gomp_team_barrier_wait_cancel_end (bar, gomp_barrier_wait_start (bar));
}
void
-gomp_barrier_wait (gomp_barrier_t *barrier)
+gomp_team_barrier_cancel (struct gomp_team *team)
{
- gomp_barrier_wait_end (barrier, gomp_barrier_wait_start (barrier));
+ gomp_mutex_lock (&team->task_lock);
+ if (team->barrier.generation & BAR_CANCELLED)
+ {
+ gomp_mutex_unlock (&team->task_lock);
+ return;
+ }
+ team->barrier.generation |= BAR_CANCELLED;
+ gomp_mutex_unlock (&team->task_lock);
+ futex_wake ((int *) &team->barrier.generation, INT_MAX);
}
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