mirror of
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321 lines
9.2 KiB
C
321 lines
9.2 KiB
C
/* Copyright (C) 2005-2022 Free Software Foundation, Inc.
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Contributed by Richard Henderson <rth@redhat.com>.
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This file is part of the GNU Offloading and Multi Processing Library
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(libgomp).
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Libgomp is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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/* This file contains routines to manage the work-share queue for a team
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of threads. */
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#include "libgomp.h"
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#include <stddef.h>
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#include <stdlib.h>
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#include <string.h>
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/* Allocate a new work share structure, preferably from current team's
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free gomp_work_share cache. */
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static struct gomp_work_share *
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alloc_work_share (struct gomp_team *team)
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{
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struct gomp_work_share *ws;
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unsigned int i;
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/* This is called in a critical section. */
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if (team->work_share_list_alloc != NULL)
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{
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ws = team->work_share_list_alloc;
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team->work_share_list_alloc = ws->next_free;
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return ws;
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}
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#ifdef HAVE_SYNC_BUILTINS
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ws = team->work_share_list_free;
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/* We need atomic read from work_share_list_free,
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as free_work_share can be called concurrently. */
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__asm ("" : "+r" (ws));
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if (ws && ws->next_free)
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{
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struct gomp_work_share *next = ws->next_free;
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ws->next_free = NULL;
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team->work_share_list_alloc = next->next_free;
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return next;
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}
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#else
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gomp_mutex_lock (&team->work_share_list_free_lock);
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ws = team->work_share_list_free;
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if (ws)
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{
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team->work_share_list_alloc = ws->next_free;
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team->work_share_list_free = NULL;
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gomp_mutex_unlock (&team->work_share_list_free_lock);
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return ws;
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}
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gomp_mutex_unlock (&team->work_share_list_free_lock);
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#endif
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team->work_share_chunk *= 2;
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/* Allocating gomp_work_share structures aligned is just an
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optimization, don't do it when using the fallback method. */
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#ifdef GOMP_USE_ALIGNED_WORK_SHARES
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ws = gomp_aligned_alloc (__alignof (struct gomp_work_share),
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team->work_share_chunk
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* sizeof (struct gomp_work_share));
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#else
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ws = gomp_malloc (team->work_share_chunk * sizeof (struct gomp_work_share));
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#endif
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ws->next_alloc = team->work_shares[0].next_alloc;
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team->work_shares[0].next_alloc = ws;
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team->work_share_list_alloc = &ws[1];
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for (i = 1; i < team->work_share_chunk - 1; i++)
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ws[i].next_free = &ws[i + 1];
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ws[i].next_free = NULL;
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return ws;
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}
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/* Initialize an already allocated struct gomp_work_share.
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This shouldn't touch the next_alloc field. */
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void
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gomp_init_work_share (struct gomp_work_share *ws, size_t ordered,
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unsigned nthreads)
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{
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gomp_mutex_init (&ws->lock);
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if (__builtin_expect (ordered, 0))
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{
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#define INLINE_ORDERED_TEAM_IDS_SIZE \
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(sizeof (struct gomp_work_share) \
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- offsetof (struct gomp_work_share, inline_ordered_team_ids))
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if (__builtin_expect (ordered != 1, 0))
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{
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size_t o = nthreads * sizeof (*ws->ordered_team_ids);
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o += __alignof__ (long long) - 1;
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if ((offsetof (struct gomp_work_share, inline_ordered_team_ids)
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& (__alignof__ (long long) - 1)) == 0
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&& __alignof__ (struct gomp_work_share)
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>= __alignof__ (long long))
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o &= ~(__alignof__ (long long) - 1);
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ordered += o - 1;
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}
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else
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ordered = nthreads * sizeof (*ws->ordered_team_ids);
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if (ordered > INLINE_ORDERED_TEAM_IDS_SIZE)
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ws->ordered_team_ids = team_malloc (ordered);
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else
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ws->ordered_team_ids = ws->inline_ordered_team_ids;
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memset (ws->ordered_team_ids, '\0', ordered);
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ws->ordered_num_used = 0;
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ws->ordered_owner = -1;
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ws->ordered_cur = 0;
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}
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else
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ws->ordered_team_ids = ws->inline_ordered_team_ids;
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gomp_ptrlock_init (&ws->next_ws, NULL);
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ws->threads_completed = 0;
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}
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/* Do any needed destruction of gomp_work_share fields before it
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is put back into free gomp_work_share cache or freed. */
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void
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gomp_fini_work_share (struct gomp_work_share *ws)
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{
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gomp_mutex_destroy (&ws->lock);
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if (ws->ordered_team_ids != ws->inline_ordered_team_ids)
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team_free (ws->ordered_team_ids);
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gomp_ptrlock_destroy (&ws->next_ws);
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}
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/* Free a work share struct, if not orphaned, put it into current
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team's free gomp_work_share cache. */
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static inline void
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free_work_share (struct gomp_team *team, struct gomp_work_share *ws)
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{
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gomp_fini_work_share (ws);
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if (__builtin_expect (team == NULL, 0))
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free (ws);
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else
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{
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struct gomp_work_share *next_ws;
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#ifdef HAVE_SYNC_BUILTINS
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do
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{
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next_ws = team->work_share_list_free;
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ws->next_free = next_ws;
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}
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while (!__sync_bool_compare_and_swap (&team->work_share_list_free,
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next_ws, ws));
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#else
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gomp_mutex_lock (&team->work_share_list_free_lock);
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next_ws = team->work_share_list_free;
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ws->next_free = next_ws;
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team->work_share_list_free = ws;
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gomp_mutex_unlock (&team->work_share_list_free_lock);
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#endif
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}
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}
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/* The current thread is ready to begin the next work sharing construct.
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In all cases, thr->ts.work_share is updated to point to the new
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structure. In all cases the work_share lock is locked. Return true
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if this was the first thread to reach this point. */
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bool
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gomp_work_share_start (size_t ordered)
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{
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struct gomp_thread *thr = gomp_thread ();
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struct gomp_team *team = thr->ts.team;
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struct gomp_work_share *ws;
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/* Work sharing constructs can be orphaned. */
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if (team == NULL)
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{
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#ifdef GOMP_USE_ALIGNED_WORK_SHARES
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ws = gomp_aligned_alloc (__alignof (struct gomp_work_share),
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sizeof (*ws));
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#else
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ws = gomp_malloc (sizeof (*ws));
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#endif
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gomp_init_work_share (ws, ordered, 1);
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thr->ts.work_share = ws;
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return true;
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}
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ws = thr->ts.work_share;
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thr->ts.last_work_share = ws;
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ws = gomp_ptrlock_get (&ws->next_ws);
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if (ws == NULL)
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{
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/* This thread encountered a new ws first. */
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struct gomp_work_share *ws = alloc_work_share (team);
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gomp_init_work_share (ws, ordered, team->nthreads);
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thr->ts.work_share = ws;
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return true;
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}
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else
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{
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thr->ts.work_share = ws;
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return false;
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}
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}
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/* The current thread is done with its current work sharing construct.
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This version does imply a barrier at the end of the work-share. */
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void
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gomp_work_share_end (void)
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{
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struct gomp_thread *thr = gomp_thread ();
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struct gomp_team *team = thr->ts.team;
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gomp_barrier_state_t bstate;
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/* Work sharing constructs can be orphaned. */
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if (team == NULL)
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{
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free_work_share (NULL, thr->ts.work_share);
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thr->ts.work_share = NULL;
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return;
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}
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bstate = gomp_barrier_wait_start (&team->barrier);
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if (gomp_barrier_last_thread (bstate))
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{
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if (__builtin_expect (thr->ts.last_work_share != NULL, 1))
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{
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team->work_shares_to_free = thr->ts.work_share;
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free_work_share (team, thr->ts.last_work_share);
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}
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}
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gomp_team_barrier_wait_end (&team->barrier, bstate);
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thr->ts.last_work_share = NULL;
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}
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/* The current thread is done with its current work sharing construct.
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This version implies a cancellable barrier at the end of the work-share. */
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bool
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gomp_work_share_end_cancel (void)
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{
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struct gomp_thread *thr = gomp_thread ();
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struct gomp_team *team = thr->ts.team;
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gomp_barrier_state_t bstate;
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/* Cancellable work sharing constructs cannot be orphaned. */
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bstate = gomp_barrier_wait_cancel_start (&team->barrier);
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if (gomp_barrier_last_thread (bstate))
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{
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if (__builtin_expect (thr->ts.last_work_share != NULL, 1))
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{
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team->work_shares_to_free = thr->ts.work_share;
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free_work_share (team, thr->ts.last_work_share);
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}
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}
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thr->ts.last_work_share = NULL;
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return gomp_team_barrier_wait_cancel_end (&team->barrier, bstate);
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}
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/* The current thread is done with its current work sharing construct.
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This version does NOT imply a barrier at the end of the work-share. */
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void
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gomp_work_share_end_nowait (void)
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{
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struct gomp_thread *thr = gomp_thread ();
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struct gomp_team *team = thr->ts.team;
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struct gomp_work_share *ws = thr->ts.work_share;
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unsigned completed;
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/* Work sharing constructs can be orphaned. */
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if (team == NULL)
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{
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free_work_share (NULL, ws);
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thr->ts.work_share = NULL;
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return;
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}
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if (__builtin_expect (thr->ts.last_work_share == NULL, 0))
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return;
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#ifdef HAVE_SYNC_BUILTINS
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completed = __sync_add_and_fetch (&ws->threads_completed, 1);
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#else
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gomp_mutex_lock (&ws->lock);
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completed = ++ws->threads_completed;
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gomp_mutex_unlock (&ws->lock);
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#endif
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if (completed == team->nthreads)
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{
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team->work_shares_to_free = thr->ts.work_share;
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free_work_share (team, thr->ts.last_work_share);
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}
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thr->ts.last_work_share = NULL;
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}
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