mirror of git://gcc.gnu.org/git/gcc.git
126 lines
3.8 KiB
C
126 lines
3.8 KiB
C
/* Copyright (C) 2005, 2008 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 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.
|
|
|
|
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
|
|
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. */
|
|
|
|
/* 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. */
|
|
|
|
/* 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 <limits.h>
|
|
#include "wait.h"
|
|
|
|
|
|
void
|
|
gomp_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state)
|
|
{
|
|
if (__builtin_expect ((state & 1) != 0, 0))
|
|
{
|
|
/* Next time we'll be awaiting TOTAL threads again. */
|
|
bar->awaited = bar->total;
|
|
atomic_write_barrier ();
|
|
bar->generation += 4;
|
|
futex_wake ((int *) &bar->generation, INT_MAX);
|
|
}
|
|
else
|
|
{
|
|
unsigned int generation = state;
|
|
|
|
do
|
|
do_wait ((int *) &bar->generation, generation);
|
|
while (bar->generation == generation);
|
|
}
|
|
}
|
|
|
|
void
|
|
gomp_barrier_wait (gomp_barrier_t *bar)
|
|
{
|
|
gomp_barrier_wait_end (bar, gomp_barrier_wait_start (bar));
|
|
}
|
|
|
|
/* 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. */
|
|
|
|
void
|
|
gomp_barrier_wait_last (gomp_barrier_t *bar)
|
|
{
|
|
gomp_barrier_state_t state = gomp_barrier_wait_start (bar);
|
|
if (state & 1)
|
|
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;
|
|
|
|
if (__builtin_expect ((state & 1) != 0, 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;
|
|
atomic_write_barrier ();
|
|
if (__builtin_expect (team->task_count, 0))
|
|
{
|
|
gomp_barrier_handle_tasks (state);
|
|
state &= ~1;
|
|
}
|
|
else
|
|
{
|
|
bar->generation = state + 3;
|
|
futex_wake ((int *) &bar->generation, INT_MAX);
|
|
return;
|
|
}
|
|
}
|
|
|
|
generation = state;
|
|
do
|
|
{
|
|
do_wait ((int *) &bar->generation, generation);
|
|
if (__builtin_expect (bar->generation & 1, 0))
|
|
gomp_barrier_handle_tasks (state);
|
|
if ((bar->generation & 2))
|
|
generation |= 2;
|
|
}
|
|
while (bar->generation != state + 4);
|
|
}
|
|
|
|
void
|
|
gomp_team_barrier_wait (gomp_barrier_t *bar)
|
|
{
|
|
gomp_team_barrier_wait_end (bar, gomp_barrier_wait_start (bar));
|
|
}
|