122 lines
3.7 KiB
C
122 lines
3.7 KiB
C
/* Copyright (C) 2005, 2008 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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#ifndef GOMP_BARRIER_H
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#define GOMP_BARRIER_H 1
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#include "mutex.h"
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typedef struct
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{
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/* Make sure total/generation is in a mostly read cacheline, while
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awaited in a separate cacheline. */
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unsigned total __attribute__((aligned (64)));
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unsigned generation;
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unsigned awaited __attribute__((aligned (64)));
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} gomp_barrier_t;
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typedef unsigned int gomp_barrier_state_t;
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static inline void gomp_barrier_init (gomp_barrier_t *bar, unsigned count)
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{
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bar->total = count;
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bar->awaited = count;
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bar->generation = 0;
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}
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static inline void gomp_barrier_reinit (gomp_barrier_t *bar, unsigned count)
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{
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__sync_fetch_and_add (&bar->awaited, count - bar->total);
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bar->total = count;
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}
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static inline void gomp_barrier_destroy (gomp_barrier_t *bar)
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{
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}
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extern void gomp_barrier_wait (gomp_barrier_t *);
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extern void gomp_barrier_wait_last (gomp_barrier_t *);
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extern void gomp_barrier_wait_end (gomp_barrier_t *, gomp_barrier_state_t);
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extern void gomp_team_barrier_wait (gomp_barrier_t *);
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extern void gomp_team_barrier_wait_end (gomp_barrier_t *,
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gomp_barrier_state_t);
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extern void gomp_team_barrier_wake (gomp_barrier_t *, int);
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static inline gomp_barrier_state_t
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gomp_barrier_wait_start (gomp_barrier_t *bar)
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{
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unsigned int ret = bar->generation & ~3;
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/* Do we need any barrier here or is __sync_add_and_fetch acting
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as the needed LoadLoad barrier already? */
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ret += __sync_add_and_fetch (&bar->awaited, -1) == 0;
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return ret;
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}
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static inline bool
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gomp_barrier_last_thread (gomp_barrier_state_t state)
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{
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return state & 1;
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}
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/* All the inlines below must be called with team->task_lock
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held. */
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static inline void
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gomp_team_barrier_set_task_pending (gomp_barrier_t *bar)
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{
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bar->generation |= 1;
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}
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static inline void
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gomp_team_barrier_clear_task_pending (gomp_barrier_t *bar)
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{
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bar->generation &= ~1;
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}
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static inline void
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gomp_team_barrier_set_waiting_for_tasks (gomp_barrier_t *bar)
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{
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bar->generation |= 2;
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}
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static inline bool
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gomp_team_barrier_waiting_for_tasks (gomp_barrier_t *bar)
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{
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return (bar->generation & 2) != 0;
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}
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static inline void
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gomp_team_barrier_done (gomp_barrier_t *bar, gomp_barrier_state_t state)
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{
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bar->generation = (state & ~3) + 4;
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}
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#endif /* GOMP_BARRIER_H */
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