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jeremybenn |
/* Copyright (C) 2005, 2008, 2009 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 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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