From 7262c91fbd64f7e78cfeccec212f61a55821f68c Mon Sep 17 00:00:00 2001 From: amodra Date: Wed, 30 Nov 2011 04:44:13 +0000 Subject: [PATCH] PR libgomp/51298 * config/linux/bar.h: Use atomic rather than sync builtins. * config/linux/bar.c: Likewise. Add missing acquire synchronisation on generation field. * task.c (gomp_barrier_handle_tasks): Regain lock so as to not double unlock. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@181833 138bc75d-0d04-0410-961f-82ee72b054a4 --- libgomp/ChangeLog | 9 +++++++++ libgomp/config/linux/bar.c | 30 ++++++++++++++++-------------- libgomp/config/linux/bar.h | 15 +++++++++------ libgomp/task.c | 1 + 4 files changed, 35 insertions(+), 20 deletions(-) diff --git a/libgomp/ChangeLog b/libgomp/ChangeLog index faa6749d824..f6278b77159 100644 --- a/libgomp/ChangeLog +++ b/libgomp/ChangeLog @@ -1,5 +1,14 @@ 2011-11-30 Alan Modra + PR libgomp/51298 + * config/linux/bar.h: Use atomic rather than sync builtins. + * config/linux/bar.c: Likewise. Add missing acquire + synchronisation on generation field. + * task.c (gomp_barrier_handle_tasks): Regain lock so as to not + double unlock. + +2011-11-30 Alan Modra + * ordered.c (gomp_ordered_sync): Add MEMMODEL_ACQ_REL fence. * critical.c (GOMP_critical_start): Add MEMMODEL_RELEASE fence. * config/linux/mutex.h: Use atomic rather than sync builtins. diff --git a/libgomp/config/linux/bar.c b/libgomp/config/linux/bar.c index 3e0379eb695..223a2aec432 100644 --- a/libgomp/config/linux/bar.c +++ b/libgomp/config/linux/bar.c @@ -1,4 +1,4 @@ -/* Copyright (C) 2005, 2008, 2009 Free Software Foundation, Inc. +/* Copyright (C) 2005, 2008, 2009, 2011 Free Software Foundation, Inc. Contributed by Richard Henderson . This file is part of the GNU OpenMP Library (libgomp). @@ -37,17 +37,15 @@ gomp_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state) { /* Next time we'll be awaiting TOTAL threads again. */ bar->awaited = bar->total; - atomic_write_barrier (); - bar->generation += 4; + __atomic_store_n (&bar->generation, bar->generation + 4, + MEMMODEL_RELEASE); futex_wake ((int *) &bar->generation, INT_MAX); } else { - unsigned int generation = state; - do - do_wait ((int *) &bar->generation, generation); - while (bar->generation == generation); + do_wait ((int *) &bar->generation, state); + while (__atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE) == state); } } @@ -81,15 +79,15 @@ gomp_team_barrier_wake (gomp_barrier_t *bar, int count) void gomp_team_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state) { - unsigned int generation; + unsigned int generation, gen; 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); @@ -97,7 +95,7 @@ gomp_team_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state) } else { - bar->generation = state + 3; + __atomic_store_n (&bar->generation, state + 3, MEMMODEL_RELEASE); futex_wake ((int *) &bar->generation, INT_MAX); return; } @@ -107,12 +105,16 @@ gomp_team_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state) do { do_wait ((int *) &bar->generation, generation); - if (__builtin_expect (bar->generation & 1, 0)) - gomp_barrier_handle_tasks (state); - if ((bar->generation & 2)) + gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE); + if (__builtin_expect (gen & 1, 0)) + { + gomp_barrier_handle_tasks (state); + gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE); + } + if ((gen & 2) != 0) generation |= 2; } - while (bar->generation != state + 4); + while (gen != state + 4); } void diff --git a/libgomp/config/linux/bar.h b/libgomp/config/linux/bar.h index 9c1a8a07687..58bd40d6989 100644 --- a/libgomp/config/linux/bar.h +++ b/libgomp/config/linux/bar.h @@ -1,4 +1,4 @@ -/* Copyright (C) 2005, 2008, 2009 Free Software Foundation, Inc. +/* Copyright (C) 2005, 2008, 2009, 2011 Free Software Foundation, Inc. Contributed by Richard Henderson . This file is part of the GNU OpenMP Library (libgomp). @@ -50,7 +50,7 @@ static inline void gomp_barrier_init (gomp_barrier_t *bar, unsigned count) static inline void gomp_barrier_reinit (gomp_barrier_t *bar, unsigned count) { - __sync_fetch_and_add (&bar->awaited, count - bar->total); + __atomic_add_fetch (&bar->awaited, count - bar->total, MEMMODEL_ACQ_REL); bar->total = count; } @@ -69,10 +69,13 @@ 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; + unsigned int ret = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE) & ~3; + /* A memory barrier is needed before exiting from the various forms + of gomp_barrier_wait, to satisfy OpenMP API version 3.1 section + 2.8.6 flush Construct, which says there is an implicit flush during + a barrier region. This is a convenient place to add the barrier, + so we use MEMMODEL_ACQ_REL here rather than MEMMODEL_ACQUIRE. */ + ret += __atomic_add_fetch (&bar->awaited, -1, MEMMODEL_ACQ_REL) == 0; return ret; } diff --git a/libgomp/task.c b/libgomp/task.c index b93f77a3816..d3d72663f35 100644 --- a/libgomp/task.c +++ b/libgomp/task.c @@ -273,6 +273,7 @@ gomp_barrier_handle_tasks (gomp_barrier_state_t state) gomp_team_barrier_done (&team->barrier, state); gomp_mutex_unlock (&team->task_lock); gomp_team_barrier_wake (&team->barrier, 0); + gomp_mutex_lock (&team->task_lock); } } } -- 2.11.0