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/* Copyright (C) 2005, 2008, 2009 Free Software Foundation, Inc.
Contributed by Richard Henderson <rth@redhat.com>.
This file is part of the GNU OpenMP Library (libgomp).
Libgomp is free software; you can redistribute it and/or modify it
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 General Public License for
more details.
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.
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. */
#ifndef GOMP_BARRIER_H
#define GOMP_BARRIER_H 1
#include "mutex.h"
typedef struct
{
/* Make sure total/generation is in a mostly read cacheline, while
awaited in a separate cacheline. */
unsigned total __attribute__((aligned (64)));
unsigned generation;
unsigned awaited __attribute__((aligned (64)));
} gomp_barrier_t;
typedef unsigned int gomp_barrier_state_t;
static inline void gomp_barrier_init (gomp_barrier_t *bar, unsigned count)
{
bar->total = count;
bar->awaited = count;
bar->generation = 0;
}
static inline void gomp_barrier_reinit (gomp_barrier_t *bar, unsigned count)
{
__sync_fetch_and_add (&bar->awaited, count - bar->total);
bar->total = count;
}
static inline void gomp_barrier_destroy (gomp_barrier_t *bar)
{
}
extern void gomp_barrier_wait (gomp_barrier_t *);
extern void gomp_barrier_wait_last (gomp_barrier_t *);
extern void gomp_barrier_wait_end (gomp_barrier_t *, gomp_barrier_state_t);
extern void gomp_team_barrier_wait (gomp_barrier_t *);
extern void gomp_team_barrier_wait_end (gomp_barrier_t *,
gomp_barrier_state_t);
extern void gomp_team_barrier_wake (gomp_barrier_t *, int);
static inline gomp_barrier_state_t
gomp_barrier_wait_start (gomp_barrier_t *bar)
{
unsigned int ret = bar->generation & ~3;
/* Do we need any barrier here or is __sync_add_and_fetch acting
as the needed LoadLoad barrier already? */
ret += __sync_add_and_fetch (&bar->awaited, -1) == 0;
return ret;
}
static inline bool
gomp_barrier_last_thread (gomp_barrier_state_t state)
{
return state & 1;
}
/* All the inlines below must be called with team->task_lock
held. */
static inline void
gomp_team_barrier_set_task_pending (gomp_barrier_t *bar)
{
bar->generation |= 1;
}
static inline void
gomp_team_barrier_clear_task_pending (gomp_barrier_t *bar)
{
bar->generation &= ~1;
}
static inline void
gomp_team_barrier_set_waiting_for_tasks (gomp_barrier_t *bar)
{
bar->generation |= 2;
}
static inline bool
gomp_team_barrier_waiting_for_tasks (gomp_barrier_t *bar)
{
return (bar->generation & 2) != 0;
}
static inline void
gomp_team_barrier_done (gomp_barrier_t *bar, gomp_barrier_state_t state)
{
bar->generation = (state & ~3) + 4;
}
#endif /* GOMP_BARRIER_H */
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