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Diffstat (limited to 'gcc-4.2.1-5666.3/libgomp/ordered.c')
| -rw-r--r-- | gcc-4.2.1-5666.3/libgomp/ordered.c | 249 |
1 files changed, 249 insertions, 0 deletions
diff --git a/gcc-4.2.1-5666.3/libgomp/ordered.c b/gcc-4.2.1-5666.3/libgomp/ordered.c new file mode 100644 index 000000000..7c5d67199 --- /dev/null +++ b/gcc-4.2.1-5666.3/libgomp/ordered.c @@ -0,0 +1,249 @@ +/* Copyright (C) 2005 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 file handles the ORDERED construct. */ + +#include "libgomp.h" + + +/* This function is called when first allocating an iteration block. That + is, the thread is not currently on the queue. The work-share lock must + be held on entry. */ + +void +gomp_ordered_first (void) +{ + struct gomp_thread *thr = gomp_thread (); + struct gomp_team *team = thr->ts.team; + struct gomp_work_share *ws = thr->ts.work_share; + unsigned index; + + /* Work share constructs can be orphaned. */ + if (team == NULL || team->nthreads == 1) + return; + + index = ws->ordered_cur + ws->ordered_num_used; + if (index >= team->nthreads) + index -= team->nthreads; + ws->ordered_team_ids[index] = thr->ts.team_id; + + /* If this is the first and only thread in the queue, then there is + no one to release us when we get to our ordered section. Post to + our own release queue now so that we won't block later. */ + if (ws->ordered_num_used++ == 0) + gomp_sem_post (team->ordered_release[thr->ts.team_id]); +} + +/* This function is called when completing the last iteration block. That + is, there are no more iterations to perform and so the thread should be + removed from the queue entirely. Because of the way ORDERED blocks are + managed, it follows that we currently own access to the ORDERED block, + and should now pass it on to the next thread. The work-share lock must + be held on entry. */ + +void +gomp_ordered_last (void) +{ + struct gomp_thread *thr = gomp_thread (); + struct gomp_team *team = thr->ts.team; + struct gomp_work_share *ws = thr->ts.work_share; + unsigned next_id; + + /* Work share constructs can be orphaned. */ + if (team == NULL || team->nthreads == 1) + return; + + /* We're no longer the owner. */ + ws->ordered_owner = -1; + + /* If we're not the last thread in the queue, then wake the next. */ + if (--ws->ordered_num_used > 0) + { + unsigned next = ws->ordered_cur + 1; + if (next == team->nthreads) + next = 0; + ws->ordered_cur = next; + + next_id = ws->ordered_team_ids[next]; + gomp_sem_post (team->ordered_release[next_id]); + } +} + + +/* This function is called when allocating a subsequent allocation block. + That is, we're done with the current iteration block and we're allocating + another. This is the logical combination of a call to gomp_ordered_last + followed by a call to gomp_ordered_first. The work-share lock must be + held on entry. */ + +void +gomp_ordered_next (void) +{ + struct gomp_thread *thr = gomp_thread (); + struct gomp_team *team = thr->ts.team; + struct gomp_work_share *ws = thr->ts.work_share; + unsigned index, next_id; + + /* Work share constructs can be orphaned. */ + if (team == NULL || team->nthreads == 1) + return; + + /* We're no longer the owner. */ + ws->ordered_owner = -1; + + /* If there's only one thread in the queue, that must be us. */ + if (ws->ordered_num_used == 1) + { + /* We have a similar situation as in gomp_ordered_first + where we need to post to our own release semaphore. */ + gomp_sem_post (team->ordered_release[thr->ts.team_id]); + return; + } + + /* If the queue is entirely full, then we move ourself to the end of + the queue merely by incrementing ordered_cur. Only if it's not + full do we have to write our id. */ + if (ws->ordered_num_used < team->nthreads) + { + index = ws->ordered_cur + ws->ordered_num_used; + if (index >= team->nthreads) + index -= team->nthreads; + ws->ordered_team_ids[index] = thr->ts.team_id; + } + + index = ws->ordered_cur + 1; + if (index == team->nthreads) + index = 0; + ws->ordered_cur = index; + + next_id = ws->ordered_team_ids[index]; + gomp_sem_post (team->ordered_release[next_id]); +} + + +/* This function is called when a statically scheduled loop is first + being created. */ + +void +gomp_ordered_static_init (void) +{ + struct gomp_thread *thr = gomp_thread (); + struct gomp_team *team = thr->ts.team; + + if (team == NULL || team->nthreads == 1) + return; + + gomp_sem_post (team->ordered_release[0]); +} + +/* This function is called when a statically scheduled loop is moving to + the next allocation block. Static schedules are not first come first + served like the others, so we're to move to the numerically next thread, + not the next thread on a list. The work-share lock should *not* be held + on entry. */ + +void +gomp_ordered_static_next (void) +{ + struct gomp_thread *thr = gomp_thread (); + struct gomp_team *team = thr->ts.team; + struct gomp_work_share *ws = thr->ts.work_share; + unsigned id = thr->ts.team_id; + + if (team == NULL || team->nthreads == 1) + return; + + ws->ordered_owner = -1; + + /* This thread currently owns the lock. Increment the owner. */ + if (++id == team->nthreads) + id = 0; + ws->ordered_team_ids[0] = id; + gomp_sem_post (team->ordered_release[id]); +} + +/* This function is called when we need to assert that the thread owns the + ordered section. Due to the problem of posted-but-not-waited semaphores, + this needs to happen before completing a loop iteration. */ + +void +gomp_ordered_sync (void) +{ + struct gomp_thread *thr = gomp_thread (); + struct gomp_team *team = thr->ts.team; + struct gomp_work_share *ws = thr->ts.work_share; + + /* Work share constructs can be orphaned. But this clearly means that + we are the only thread, and so we automatically own the section. */ + if (team == NULL || team->nthreads == 1) + return; + + /* ??? I believe it to be safe to access this data without taking the + ws->lock. The only presumed race condition is with the previous + thread on the queue incrementing ordered_cur such that it points + to us, concurrently with our check below. But our team_id is + already present in the queue, and the other thread will always + post to our release semaphore. So the two cases are that we will + either win the race an momentarily block on the semaphore, or lose + the race and find the semaphore already unlocked and so not block. + Either way we get correct results. */ + + if (ws->ordered_owner != thr->ts.team_id) + { + gomp_sem_wait (team->ordered_release[thr->ts.team_id]); + ws->ordered_owner = thr->ts.team_id; + } +} + +/* This function is called by user code when encountering the start of an + ORDERED block. We must check to see if the current thread is at the + head of the queue, and if not, block. */ + +#ifdef HAVE_ATTRIBUTE_ALIAS +extern void GOMP_ordered_start (void) + __attribute__((alias ("gomp_ordered_sync"))); +#else +void +GOMP_ordered_start (void) +{ + gomp_ordered_sync (); +} +#endif + +/* This function is called by user code when encountering the end of an + ORDERED block. With the current ORDERED implementation there's nothing + for us to do. + + However, the current implementation has a flaw in that it does not allow + the next thread into the ORDERED section immediately after the current + thread exits the ORDERED section in its last iteration. The existance + of this function allows the implementation to change. */ + +void +GOMP_ordered_end (void) +{ +} |