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Diffstat (limited to 'libgomp/config/rtems/bar.c')
| -rw-r--r-- | libgomp/config/rtems/bar.c | 255 |
1 files changed, 255 insertions, 0 deletions
diff --git a/libgomp/config/rtems/bar.c b/libgomp/config/rtems/bar.c new file mode 100644 index 00000000000..e5b3f76c581 --- /dev/null +++ b/libgomp/config/rtems/bar.c @@ -0,0 +1,255 @@ +/* Copyright (C) 2005-2015 Free Software Foundation, Inc. + Contributed by Sebastian Huber <sebastian.huber@embedded-brains.de>. + + 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 the RTEMS implementation of a barrier synchronization + mechanism for libgomp. It is identical to the Linux implementation, except + that the futex API is slightly different. This type is private to the + library. */ + +#include "libgomp.h" +#include "bar.h" +#include <limits.h> + +static gomp_barrier_t * +generation_to_barrier (int *addr) +{ + return (gomp_barrier_t *) + ((char *) addr - __builtin_offsetof (gomp_barrier_t, generation)); +} + +static void +futex_wait (int *addr, int val) +{ + gomp_barrier_t *bar = generation_to_barrier (addr); + _Futex_Wait (&bar->futex, addr, val); +} + +static void +futex_wake (int *addr, int count) +{ + gomp_barrier_t *bar = generation_to_barrier (addr); + _Futex_Wake (&bar->futex, count); +} + +static int +do_spin (int *addr, int val) +{ + unsigned long long i, count = gomp_spin_count_var; + + if (__builtin_expect (gomp_managed_threads > gomp_available_cpus, 0)) + count = gomp_throttled_spin_count_var; + for (i = 0; i < count; i++) + if (__builtin_expect (__atomic_load_n (addr, MEMMODEL_RELAXED) != val, 0)) + return 0; + return 1; +} + +static void +do_wait (int *addr, int val) +{ + if (do_spin (addr, val)) + futex_wait (addr, val); +} + +/* Everything below this point should be identical to the Linux + implementation. */ + +void +gomp_barrier_wait_end (gomp_barrier_t *bar, gomp_barrier_state_t state) +{ + if (__builtin_expect (state & BAR_WAS_LAST, 0)) + { + /* Next time we'll be awaiting TOTAL threads again. */ + bar->awaited = bar->total; + __atomic_store_n (&bar->generation, bar->generation + BAR_INCR, + MEMMODEL_RELEASE); + futex_wake ((int *) &bar->generation, INT_MAX); + } + else + { + do + do_wait ((int *) &bar->generation, state); + while (__atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE) == state); + } +} + +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 & BAR_WAS_LAST) + 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, gen; + + if (__builtin_expect (state & BAR_WAS_LAST, 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; + team->work_share_cancelled = 0; + if (__builtin_expect (team->task_count, 0)) + { + gomp_barrier_handle_tasks (state); + state &= ~BAR_WAS_LAST; + } + else + { + state &= ~BAR_CANCELLED; + state += BAR_INCR - BAR_WAS_LAST; + __atomic_store_n (&bar->generation, state, MEMMODEL_RELEASE); + futex_wake ((int *) &bar->generation, INT_MAX); + return; + } + } + + generation = state; + state &= ~BAR_CANCELLED; + do + { + do_wait ((int *) &bar->generation, generation); + gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE); + if (__builtin_expect (gen & BAR_TASK_PENDING, 0)) + { + gomp_barrier_handle_tasks (state); + gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE); + } + generation |= gen & BAR_WAITING_FOR_TASK; + } + while (gen != state + BAR_INCR); +} + +void +gomp_team_barrier_wait (gomp_barrier_t *bar) +{ + gomp_team_barrier_wait_end (bar, gomp_barrier_wait_start (bar)); +} + +void +gomp_team_barrier_wait_final (gomp_barrier_t *bar) +{ + gomp_barrier_state_t state = gomp_barrier_wait_final_start (bar); + if (__builtin_expect (state & BAR_WAS_LAST, 0)) + bar->awaited_final = bar->total; + gomp_team_barrier_wait_end (bar, state); +} + +bool +gomp_team_barrier_wait_cancel_end (gomp_barrier_t *bar, + gomp_barrier_state_t state) +{ + unsigned int generation, gen; + + if (__builtin_expect (state & BAR_WAS_LAST, 0)) + { + /* Next time we'll be awaiting TOTAL threads again. */ + /* BAR_CANCELLED should never be set in state here, because + cancellation means that at least one of the threads has been + cancelled, thus on a cancellable barrier we should never see + all threads to arrive. */ + struct gomp_thread *thr = gomp_thread (); + struct gomp_team *team = thr->ts.team; + + bar->awaited = bar->total; + team->work_share_cancelled = 0; + if (__builtin_expect (team->task_count, 0)) + { + gomp_barrier_handle_tasks (state); + state &= ~BAR_WAS_LAST; + } + else + { + state += BAR_INCR - BAR_WAS_LAST; + __atomic_store_n (&bar->generation, state, MEMMODEL_RELEASE); + futex_wake ((int *) &bar->generation, INT_MAX); + return false; + } + } + + if (__builtin_expect (state & BAR_CANCELLED, 0)) + return true; + + generation = state; + do + { + do_wait ((int *) &bar->generation, generation); + gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE); + if (__builtin_expect (gen & BAR_CANCELLED, 0)) + return true; + if (__builtin_expect (gen & BAR_TASK_PENDING, 0)) + { + gomp_barrier_handle_tasks (state); + gen = __atomic_load_n (&bar->generation, MEMMODEL_ACQUIRE); + } + generation |= gen & BAR_WAITING_FOR_TASK; + } + while (gen != state + BAR_INCR); + + return false; +} + +bool +gomp_team_barrier_wait_cancel (gomp_barrier_t *bar) +{ + return gomp_team_barrier_wait_cancel_end (bar, gomp_barrier_wait_start (bar)); +} + +void +gomp_team_barrier_cancel (struct gomp_team *team) +{ + gomp_mutex_lock (&team->task_lock); + if (team->barrier.generation & BAR_CANCELLED) + { + gomp_mutex_unlock (&team->task_lock); + return; + } + team->barrier.generation |= BAR_CANCELLED; + gomp_mutex_unlock (&team->task_lock); + futex_wake ((int *) &team->barrier.generation, INT_MAX); +} |