65 lines
2.1 KiB
C
65 lines
2.1 KiB
C
/* Copyright (C) 2005 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 Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) 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 Lesser General Public License for
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more details.
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You should have received a copy of the GNU Lesser General Public License
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along with libgomp; see the file COPYING.LIB. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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/* As a special exception, if you link this library with other files, some
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of which are compiled with GCC, to produce an executable, this library
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does not by itself cause the resulting executable to be covered by the
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GNU General Public License. This exception does not however invalidate
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any other reasons why the executable file might be covered by the GNU
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General Public License. */
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/* This is a Linux specific implementation of a barrier synchronization
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mechanism for libgomp. This type is private to the library. This
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implementation uses atomic instructions and the futex syscall. */
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#include "libgomp.h"
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#include "futex.h"
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#include <limits.h>
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void
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gomp_barrier_wait_end (gomp_barrier_t *bar, bool last)
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{
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if (last)
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{
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bar->generation++;
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futex_wake (&bar->generation, INT_MAX);
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}
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else
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{
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unsigned int generation = bar->generation;
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gomp_mutex_unlock (&bar->mutex);
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do
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futex_wait (&bar->generation, generation);
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while (bar->generation == generation);
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}
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if (__sync_add_and_fetch (&bar->arrived, -1) == 0)
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gomp_mutex_unlock (&bar->mutex);
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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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