1*404b540aSrobert /* Copyright (C) 2005 Free Software Foundation, Inc.
2*404b540aSrobert Contributed by Richard Henderson <rth@redhat.com>.
3*404b540aSrobert
4*404b540aSrobert This file is part of the GNU OpenMP Library (libgomp).
5*404b540aSrobert
6*404b540aSrobert Libgomp is free software; you can redistribute it and/or modify it
7*404b540aSrobert under the terms of the GNU Lesser General Public License as published by
8*404b540aSrobert the Free Software Foundation; either version 2.1 of the License, or
9*404b540aSrobert (at your option) any later version.
10*404b540aSrobert
11*404b540aSrobert Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
12*404b540aSrobert WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
13*404b540aSrobert FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
14*404b540aSrobert more details.
15*404b540aSrobert
16*404b540aSrobert You should have received a copy of the GNU Lesser General Public License
17*404b540aSrobert along with libgomp; see the file COPYING.LIB. If not, write to the
18*404b540aSrobert Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
19*404b540aSrobert MA 02110-1301, USA. */
20*404b540aSrobert
21*404b540aSrobert /* As a special exception, if you link this library with other files, some
22*404b540aSrobert of which are compiled with GCC, to produce an executable, this library
23*404b540aSrobert does not by itself cause the resulting executable to be covered by the
24*404b540aSrobert GNU General Public License. This exception does not however invalidate
25*404b540aSrobert any other reasons why the executable file might be covered by the GNU
26*404b540aSrobert General Public License. */
27*404b540aSrobert
28*404b540aSrobert /* This is a Linux specific implementation of a barrier synchronization
29*404b540aSrobert mechanism for libgomp. This type is private to the library. This
30*404b540aSrobert implementation uses atomic instructions and the futex syscall. */
31*404b540aSrobert
32*404b540aSrobert #include "libgomp.h"
33*404b540aSrobert #include "futex.h"
34*404b540aSrobert #include <limits.h>
35*404b540aSrobert
36*404b540aSrobert
37*404b540aSrobert void
gomp_barrier_wait_end(gomp_barrier_t * bar,bool last)38*404b540aSrobert gomp_barrier_wait_end (gomp_barrier_t *bar, bool last)
39*404b540aSrobert {
40*404b540aSrobert if (last)
41*404b540aSrobert {
42*404b540aSrobert bar->generation++;
43*404b540aSrobert futex_wake (&bar->generation, INT_MAX);
44*404b540aSrobert }
45*404b540aSrobert else
46*404b540aSrobert {
47*404b540aSrobert unsigned int generation = bar->generation;
48*404b540aSrobert
49*404b540aSrobert gomp_mutex_unlock (&bar->mutex);
50*404b540aSrobert
51*404b540aSrobert do
52*404b540aSrobert futex_wait (&bar->generation, generation);
53*404b540aSrobert while (bar->generation == generation);
54*404b540aSrobert }
55*404b540aSrobert
56*404b540aSrobert if (__sync_add_and_fetch (&bar->arrived, -1) == 0)
57*404b540aSrobert gomp_mutex_unlock (&bar->mutex);
58*404b540aSrobert }
59*404b540aSrobert
60*404b540aSrobert void
gomp_barrier_wait(gomp_barrier_t * barrier)61*404b540aSrobert gomp_barrier_wait (gomp_barrier_t *barrier)
62*404b540aSrobert {
63*404b540aSrobert gomp_barrier_wait_end (barrier, gomp_barrier_wait_start (barrier));
64*404b540aSrobert }
65