libgomp/config/gcn/team.c

/* Copyright (C) 2017-2019 Free Software Foundation, Inc.
   Contributed by Mentor Embedded.

   This file is part of the GNU Offloading and Multi Processing 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 maintainance of threads on AMD GCN.  */

#include "libgomp.h"
#include <stdlib.h>
#include <string.h>

static void gomp_thread_start (struct gomp_thread_pool *);
void gomp_print_string (const char *msg, const char *val);

/* This externally visible function handles target region entry.  It
   sets up a per-team thread pool and transfers control by returning to
   the kernel in the master thread or gomp_thread_start in other threads.

   The name of this function is part of the interface with the compiler: for
   each OpenMP kernel the compiler configures the stack, then calls here.

   Likewise, gomp_gcn_exit_kernel is called during the kernel epilogue.  */

void
gomp_gcn_enter_kernel (void)
{
  int tid, ntids;
  tid = __builtin_gcn_dim_pos (1);
  ntids = __builtin_gcn_dim_size (1);
  if (tid == 0)
    {
      gomp_global_icv.nthreads_var = ntids;
      /* Starting additional threads is not supported.  */
      gomp_global_icv.dyn_var = true;

      set_gcn_thrs (calloc (ntids, sizeof (struct gomp_thread)));
      if (gcn_thrs () == NULL)
	goto oom;

      struct gomp_thread_pool *pool = malloc (sizeof (*pool));
      if (pool == NULL)
	goto oom;

      pool->threads = malloc (ntids * sizeof (*pool->threads));
      if (pool->threads == NULL)
	goto oom;

      for (tid = 0; tid < ntids; tid++)
	pool->threads[tid] = gcn_thrs () + tid;
      pool->threads_size = ntids;
      pool->threads_used = ntids;
      pool->threads_busy = 1;
      pool->last_team = NULL;
      gomp_simple_barrier_init (&pool->threads_dock, ntids);

      gcn_thrs ()[0].thread_pool = pool;
      asm ("s_barrier" ::: "memory");
      return;  /* Return to kernel.  */
    }
  else
    {
      asm ("s_barrier" ::: "memory");
      gomp_thread_start (gcn_thrs ()[0].thread_pool);
      /* gomp_thread_start does not return.  */
    }

oom:
  gomp_print_string ("GCN heap exhausted; try setting GCN_HEAP_SIZE.", "");
  abort();
}

void
gomp_gcn_exit_kernel (void)
{
  gomp_free_thread (gcn_thrs ());
  free (gcn_thrs ());
}

/* This function contains the idle loop in which a thread waits
   to be called up to become part of a team.  */

static void
gomp_thread_start (struct gomp_thread_pool *pool)
{
  struct gomp_thread *thr = gomp_thread ();

  gomp_sem_init (&thr->release, 0);
  thr->thread_pool = pool;

  /* The loop exits only when "fn" is assigned "gomp_free_pool_helper",
     which contains "s_endpgm", or an infinite no-op loop is
     suspected (this happens when the thread master crashes).  */
  int nul_limit = 99;
  do
    {
      gomp_simple_barrier_wait (&pool->threads_dock);
      if (!thr->fn)
	{
	  if (nul_limit-- > 0)
	    continue;
	  else
	    {
	      gomp_print_string ("team master not responding;",
				 " slave thread aborting");
	      abort();
	    }
	}
      thr->fn (thr->data);
      thr->fn = NULL;

      struct gomp_task *task = thr->task;
      gomp_team_barrier_wait_final (&thr->ts.team->barrier);
      gomp_finish_task (task);
    }
  while (1);
}

/* Launch a team.  */

void
gomp_team_start (void (*fn) (void *), void *data, unsigned nthreads,
		 unsigned flags, struct gomp_team *team,
		 struct gomp_taskgroup *taskgroup)
{
  struct gomp_thread *thr, *nthr;
  struct gomp_task *task;
  struct gomp_task_icv *icv;
  struct gomp_thread_pool *pool;
  unsigned long nthreads_var;

  thr = gomp_thread ();
  pool = thr->thread_pool;
  task = thr->task;
  icv = task ? &task->icv : &gomp_global_icv;

  /* Always save the previous state, even if this isn't a nested team.
     In particular, we should save any work share state from an outer
     orphaned work share construct.  */
  team->prev_ts = thr->ts;

  thr->ts.team = team;
  thr->ts.team_id = 0;
  ++thr->ts.level;
  if (nthreads > 1)
    ++thr->ts.active_level;
  thr->ts.work_share = &team->work_shares[0];
  thr->ts.last_work_share = NULL;
  thr->ts.single_count = 0;
  thr->ts.static_trip = 0;
  thr->task = &team->implicit_task[0];
  nthreads_var = icv->nthreads_var;
  gomp_init_task (thr->task, task, icv);
  team->implicit_task[0].icv.nthreads_var = nthreads_var;
  team->implicit_task[0].taskgroup = taskgroup;

  if (nthreads == 1)
    return;

  /* Release existing idle threads.  */
  for (unsigned i = 1; i < nthreads; ++i)
    {
      nthr = pool->threads[i];
      nthr->ts.team = team;
      nthr->ts.work_share = &team->work_shares[0];
      nthr->ts.last_work_share = NULL;
      nthr->ts.team_id = i;
      nthr->ts.level = team->prev_ts.level + 1;
      nthr->ts.active_level = thr->ts.active_level;
      nthr->ts.single_count = 0;
      nthr->ts.static_trip = 0;
      nthr->task = &team->implicit_task[i];
      gomp_init_task (nthr->task, task, icv);
      team->implicit_task[i].icv.nthreads_var = nthreads_var;
      team->implicit_task[i].taskgroup = taskgroup;
      nthr->fn = fn;
      nthr->data = data;
      team->ordered_release[i] = &nthr->release;
    }

  gomp_simple_barrier_wait (&pool->threads_dock);
}

#include "../../team.c"