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/* Copyright (C) 2007, 2008, 2009 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 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 file handles the maintainence of tasks in response to task

   creation and termination.  */

#include "libgomp.h"

#include <stdlib.h>

#include <string.h>

/* Create a new task data structure.  */

void

gomp_init_task (struct gomp_task *task, struct gomp_task *parent_task,

                struct gomp_task_icv *prev_icv)

{

  task->parent = parent_task;

  task->icv = *prev_icv;

  task->kind = GOMP_TASK_IMPLICIT;

  task->in_taskwait = false;

  task->in_tied_task = false;

  task->children = NULL;

  gomp_sem_init (&task->taskwait_sem, 0);

}

/* Clean up a task, after completing it.  */

void

gomp_end_task (void)

{

  struct gomp_thread *thr = gomp_thread ();

  struct gomp_task *task = thr->task;

  gomp_finish_task (task);

  thr->task = task->parent;

}

static inline void

gomp_clear_parent (struct gomp_task *children)

{

  struct gomp_task *task = children;

  if (task)

    do

      {

        task->parent = NULL;

        task = task->next_child;

      }

    while (task != children);

}

/* Called when encountering an explicit task directive.  If IF_CLAUSE is

   false, then we must not delay in executing the task.  If UNTIED is true,

   then the task may be executed by any member of the team.  */

void

GOMP_task (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *),

           long arg_size, long arg_align, bool if_clause,

           unsigned flags __attribute__((unused)))

{

  struct gomp_thread *thr = gomp_thread ();

  struct gomp_team *team = thr->ts.team;

#ifdef HAVE_BROKEN_POSIX_SEMAPHORES

  /* If pthread_mutex_* is used for omp_*lock*, then each task must be

     tied to one thread all the time.  This means UNTIED tasks must be

     tied and if CPYFN is non-NULL IF(0) must be forced, as CPYFN

     might be running on different thread than FN.  */

  if (cpyfn)

    if_clause = false;

  if (flags & 1)

    flags &= ~1;

#endif

  if (!if_clause || team == NULL

      || team->task_count > 64 * team->nthreads)

    {

      struct gomp_task task;

      gomp_init_task (&task, thr->task, gomp_icv (false));

      task.kind = GOMP_TASK_IFFALSE;

      if (thr->task)

        task.in_tied_task = thr->task->in_tied_task;

      thr->task = &task;

      if (__builtin_expect (cpyfn != NULL, 0))

        {

          char buf[arg_size + arg_align - 1];

          char *arg = (char *) (((uintptr_t) buf + arg_align - 1)

                                & ~(uintptr_t) (arg_align - 1));

          cpyfn (arg, data);

          fn (arg);

        }

      else

        fn (data);

      if (task.children)

        {

          gomp_mutex_lock (&team->task_lock);

          gomp_clear_parent (task.children);

          gomp_mutex_unlock (&team->task_lock);

        }

      gomp_end_task ();

    }

  else

    {

      struct gomp_task *task;

      struct gomp_task *parent = thr->task;

      char *arg;

      bool do_wake;

      task = gomp_malloc (sizeof (*task) + arg_size + arg_align - 1);

      arg = (char *) (((uintptr_t) (task + 1) + arg_align - 1)

                      & ~(uintptr_t) (arg_align - 1));

      gomp_init_task (task, parent, gomp_icv (false));

      task->kind = GOMP_TASK_IFFALSE;

      task->in_tied_task = parent->in_tied_task;

      thr->task = task;

      if (cpyfn)

        cpyfn (arg, data);

      else

        memcpy (arg, data, arg_size);

      thr->task = parent;

      task->kind = GOMP_TASK_WAITING;

      task->fn = fn;

      task->fn_data = arg;

      task->in_tied_task = true;

      gomp_mutex_lock (&team->task_lock);

      if (parent->children)

        {

          task->next_child = parent->children;

          task->prev_child = parent->children->prev_child;

          task->next_child->prev_child = task;

          task->prev_child->next_child = task;

        }

      else

        {

          task->next_child = task;

          task->prev_child = task;

        }

      parent->children = task;

      if (team->task_queue)

        {

          task->next_queue = team->task_queue;

          task->prev_queue = team->task_queue->prev_queue;

          task->next_queue->prev_queue = task;

          task->prev_queue->next_queue = task;

        }

      else

        {

          task->next_queue = task;

          task->prev_queue = task;

          team->task_queue = task;

        }

      ++team->task_count;

      gomp_team_barrier_set_task_pending (&team->barrier);

      do_wake = team->task_running_count + !parent->in_tied_task

                < team->nthreads;

      gomp_mutex_unlock (&team->task_lock);

      if (do_wake)

        gomp_team_barrier_wake (&team->barrier, 1);

    }

}

void

gomp_barrier_handle_tasks (gomp_barrier_state_t state)

{

  struct gomp_thread *thr = gomp_thread ();

  struct gomp_team *team = thr->ts.team;

  struct gomp_task *task = thr->task;

  struct gomp_task *child_task = NULL;

  struct gomp_task *to_free = NULL;

  gomp_mutex_lock (&team->task_lock);

  if (gomp_barrier_last_thread (state))

    {

      if (team->task_count == 0)

        {

          gomp_team_barrier_done (&team->barrier, state);

          gomp_mutex_unlock (&team->task_lock);

          gomp_team_barrier_wake (&team->barrier, 0);

          return;

        }

      gomp_team_barrier_set_waiting_for_tasks (&team->barrier);

    }

  while (1)

    {

      if (team->task_queue != NULL)

        {

          struct gomp_task *parent;

          child_task = team->task_queue;

          parent = child_task->parent;

          if (parent && parent->children == child_task)

            parent->children = child_task->next_child;

          child_task->prev_queue->next_queue = child_task->next_queue;

          child_task->next_queue->prev_queue = child_task->prev_queue;

          if (child_task->next_queue != child_task)

            team->task_queue = child_task->next_queue;

          else

            team->task_queue = NULL;

          child_task->kind = GOMP_TASK_TIED;

          team->task_running_count++;

          if (team->task_count == team->task_running_count)

            gomp_team_barrier_clear_task_pending (&team->barrier);

        }

      gomp_mutex_unlock (&team->task_lock);

      if (to_free)

        {

          gomp_finish_task (to_free);

          free (to_free);

          to_free = NULL;

        }

      if (child_task)

        {

          thr->task = child_task;

          child_task->fn (child_task->fn_data);

          thr->task = task;

        }

      else

        return;

      gomp_mutex_lock (&team->task_lock);

      if (child_task)

        {

          struct gomp_task *parent = child_task->parent;

          if (parent)

            {

              child_task->prev_child->next_child = child_task->next_child;

              child_task->next_child->prev_child = child_task->prev_child;

              if (parent->children == child_task)

                {

                  if (child_task->next_child != child_task)

                    parent->children = child_task->next_child;

                  else

                    {

                      parent->children = NULL;

                      if (parent->in_taskwait)

                        gomp_sem_post (&parent->taskwait_sem);

                    }

                }

            }

          gomp_clear_parent (child_task->children);

          to_free = child_task;

          child_task = NULL;

          team->task_running_count--;

          if (--team->task_count == 0

              && gomp_team_barrier_waiting_for_tasks (&team->barrier))

            {

              gomp_team_barrier_done (&team->barrier, state);

              gomp_mutex_unlock (&team->task_lock);

              gomp_team_barrier_wake (&team->barrier, 0);

            }

        }

    }

}

/* Called when encountering a taskwait directive.  */

void

GOMP_taskwait (void)

{

  struct gomp_thread *thr = gomp_thread ();

  struct gomp_team *team = thr->ts.team;

  struct gomp_task *task = thr->task;

  struct gomp_task *child_task = NULL;

  struct gomp_task *to_free = NULL;

  if (task == NULL || task->children == NULL)

    return;

  gomp_mutex_lock (&team->task_lock);

  while (1)

    {

      if (task->children == NULL)

        {

          gomp_mutex_unlock (&team->task_lock);

          if (to_free)

            {

              gomp_finish_task (to_free);

              free (to_free);

            }

          return;

        }

      if (task->children->kind == GOMP_TASK_WAITING)

        {

          child_task = task->children;

          task->children = child_task->next_child;

          child_task->prev_queue->next_queue = child_task->next_queue;

          child_task->next_queue->prev_queue = child_task->prev_queue;

          if (team->task_queue == child_task)

            {

              if (child_task->next_queue != child_task)

                team->task_queue = child_task->next_queue;

              else

                team->task_queue = NULL;

            }

          child_task->kind = GOMP_TASK_TIED;

          team->task_running_count++;

          if (team->task_count == team->task_running_count)

            gomp_team_barrier_clear_task_pending (&team->barrier);

        }

      else

        /* All tasks we are waiting for are already running

           in other threads.  Wait for them.  */

        task->in_taskwait = true;

      gomp_mutex_unlock (&team->task_lock);

      if (to_free)

        {

          gomp_finish_task (to_free);

          free (to_free);

          to_free = NULL;

        }

      if (child_task)

        {

          thr->task = child_task;

          child_task->fn (child_task->fn_data);

          thr->task = task;

        }

      else

        {

          gomp_sem_wait (&task->taskwait_sem);

          task->in_taskwait = false;

          return;

        }

      gomp_mutex_lock (&team->task_lock);

      if (child_task)

        {

          child_task->prev_child->next_child = child_task->next_child;

          child_task->next_child->prev_child = child_task->prev_child;

          if (task->children == child_task)

            {

              if (child_task->next_child != child_task)

                task->children = child_task->next_child;

              else

                task->children = NULL;

            }

          gomp_clear_parent (child_task->children);

          to_free = child_task;

          child_task = NULL;

          team->task_count--;

          team->task_running_count--;

        }

    }

}