aboutsummaryrefslogtreecommitdiff
path: root/libgomp/taskloop.c
blob: af175f4ac1470a0e526039c11e647db372720be4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
/* Copyright (C) 2015-2022 Free Software Foundation, Inc.
   Contributed by Jakub Jelinek <jakub@redhat.com>.

   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 the taskloop construct.  It is included twice, once
   for the long and once for unsigned long long variant.  */

/* 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_taskloop (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *),
	       long arg_size, long arg_align, unsigned flags,
	       unsigned long num_tasks, int priority,
	       TYPE start, TYPE end, TYPE step)
{
  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)
    flags &= ~GOMP_TASK_FLAG_IF;
  flags &= ~GOMP_TASK_FLAG_UNTIED;
#endif

  /* If parallel or taskgroup has been cancelled, don't start new tasks.  */
  if (team && gomp_team_barrier_cancelled (&team->barrier))
    {
    early_return:
      if ((flags & (GOMP_TASK_FLAG_NOGROUP | GOMP_TASK_FLAG_REDUCTION))
	  == GOMP_TASK_FLAG_REDUCTION)
	{
	  struct gomp_data_head { TYPE t1, t2; uintptr_t *ptr; };
	  uintptr_t *ptr = ((struct gomp_data_head *) data)->ptr;
	  /* Tell callers GOMP_taskgroup_reduction_register has not been
	     called.  */
	  ptr[2] = 0;
	}
      return;
    }

#ifdef TYPE_is_long
  TYPE s = step;
  if (step > 0)
    {
      if (start >= end)
	goto early_return;
      s--;
    }
  else
    {
      if (start <= end)
	goto early_return;
      s++;
    }
  UTYPE n = (end - start + s) / step;
#else
  UTYPE n;
  if (flags & GOMP_TASK_FLAG_UP)
    {
      if (start >= end)
	goto early_return;
      n = (end - start + step - 1) / step;
    }
  else
    {
      if (start <= end)
	goto early_return;
      n = (start - end - step - 1) / -step;
    }
#endif

  TYPE task_step = step;
  TYPE nfirst_task_step = step;
  unsigned long nfirst = n;
  if (flags & GOMP_TASK_FLAG_GRAINSIZE)
    {
      unsigned long grainsize = num_tasks;
#ifdef TYPE_is_long
      num_tasks = n / grainsize;
#else
      UTYPE ndiv = n / grainsize;
      num_tasks = ndiv;
      if (num_tasks != ndiv)
	num_tasks = ~0UL;
#endif
      if ((flags & GOMP_TASK_FLAG_STRICT)
	  && num_tasks != ~0ULL)
	{
	  UTYPE mod = n % grainsize;
	  task_step = (TYPE) grainsize * step;
	  if (mod)
	    {
	      num_tasks++;
	      nfirst_task_step = (TYPE) mod * step;
	      if (num_tasks == 1)
		task_step = nfirst_task_step;
	      else
		nfirst = num_tasks - 2;
	    }
	}
      else if (num_tasks <= 1)
	{
	  num_tasks = 1;
	  task_step = end - start;
	}
      else if (num_tasks >= grainsize
#ifndef TYPE_is_long
	       && num_tasks != ~0UL
#endif
	      )
	{
	  UTYPE mul = num_tasks * grainsize;
	  task_step = (TYPE) grainsize * step;
	  if (mul != n)
	    {
	      nfirst_task_step = task_step;
	      task_step += step;
	      nfirst = n - mul - 1;
	    }
	}
      else
	{
	  UTYPE div = n / num_tasks;
	  UTYPE mod = n % num_tasks;
	  task_step = (TYPE) div * step;
	  if (mod)
	    {
	      nfirst_task_step = task_step;
	      task_step += step;
	      nfirst = mod - 1;
	    }
	}
    }
  else
    {
      if (num_tasks == 0)
	num_tasks = team ? team->nthreads : 1;
      if (num_tasks >= n)
	num_tasks = n;
      else
	{
	  UTYPE div = n / num_tasks;
	  UTYPE mod = n % num_tasks;
	  task_step = (TYPE) div * step;
	  if (mod)
	    {
	      nfirst_task_step = task_step;
	      task_step += step;
	      nfirst = mod - 1;
	    }
	}
    }

  if (flags & GOMP_TASK_FLAG_NOGROUP)
    {
      if (__builtin_expect (gomp_cancel_var, 0)
	  && thr->task
	  && thr->task->taskgroup)
	{
	  if (thr->task->taskgroup->cancelled)
	    return;
	  if (thr->task->taskgroup->workshare
	      && thr->task->taskgroup->prev
	      && thr->task->taskgroup->prev->cancelled)
	    return;
	}
    }
  else
    {
      ialias_call (GOMP_taskgroup_start) ();
      if (flags & GOMP_TASK_FLAG_REDUCTION)
	{
	  struct gomp_data_head { TYPE t1, t2; uintptr_t *ptr; };
	  uintptr_t *ptr = ((struct gomp_data_head *) data)->ptr;
	  ialias_call (GOMP_taskgroup_reduction_register) (ptr);
	}
    }

  if (priority > gomp_max_task_priority_var)
    priority = gomp_max_task_priority_var;

  if ((flags & GOMP_TASK_FLAG_IF) == 0 || team == NULL
      || (thr->task && thr->task->final_task)
      || team->task_count + num_tasks > 64 * team->nthreads)
    {
      unsigned long i;
      if (__builtin_expect (cpyfn != NULL, 0))
	{
	  struct gomp_task task[num_tasks];
	  struct gomp_task *parent = thr->task;
	  arg_size = (arg_size + arg_align - 1) & ~(arg_align - 1);
	  char buf[num_tasks * arg_size + arg_align - 1];
	  char *arg = (char *) (((uintptr_t) buf + arg_align - 1)
				& ~(uintptr_t) (arg_align - 1));
	  char *orig_arg = arg;
	  for (i = 0; i < num_tasks; i++)
	    {
	      gomp_init_task (&task[i], parent, gomp_icv (false));
	      task[i].priority = priority;
	      task[i].kind = GOMP_TASK_UNDEFERRED;
	      task[i].final_task = (thr->task && thr->task->final_task)
				   || (flags & GOMP_TASK_FLAG_FINAL);
	      if (thr->task)
		{
		  task[i].in_tied_task = thr->task->in_tied_task;
		  task[i].taskgroup = thr->task->taskgroup;
		}
	      thr->task = &task[i];
	      cpyfn (arg, data);
	      arg += arg_size;
	    }
	  arg = orig_arg;
	  for (i = 0; i < num_tasks; i++)
	    {
	      thr->task = &task[i];
	      ((TYPE *)arg)[0] = start;
	      start += task_step;
	      ((TYPE *)arg)[1] = start;
	      if (i == nfirst)
		task_step = nfirst_task_step;
	      fn (arg);
	      arg += arg_size;
	      if (!priority_queue_empty_p (&task[i].children_queue,
					   MEMMODEL_RELAXED))
		{
		  gomp_mutex_lock (&team->task_lock);
		  gomp_clear_parent (&task[i].children_queue);
		  gomp_mutex_unlock (&team->task_lock);
		}
	      gomp_end_task ();
	    }
	}
      else
	for (i = 0; i < num_tasks; i++)
	  {
	    struct gomp_task task;

	    gomp_init_task (&task, thr->task, gomp_icv (false));
	    task.priority = priority;
	    task.kind = GOMP_TASK_UNDEFERRED;
	    task.final_task = (thr->task && thr->task->final_task)
			      || (flags & GOMP_TASK_FLAG_FINAL);
	    if (thr->task)
	      {
		task.in_tied_task = thr->task->in_tied_task;
		task.taskgroup = thr->task->taskgroup;
	      }
	    thr->task = &task;
	    ((TYPE *)data)[0] = start;
	    start += task_step;
	    ((TYPE *)data)[1] = start;
	    if (i == nfirst)
	      task_step = nfirst_task_step;
	    fn (data);
	    if (!priority_queue_empty_p (&task.children_queue,
					 MEMMODEL_RELAXED))
	      {
		gomp_mutex_lock (&team->task_lock);
		gomp_clear_parent (&task.children_queue);
		gomp_mutex_unlock (&team->task_lock);
	      }
	    gomp_end_task ();
	  }
    }
  else
    {
      struct gomp_task *tasks[num_tasks];
      struct gomp_task *parent = thr->task;
      struct gomp_taskgroup *taskgroup = parent->taskgroup;
      char *arg;
      int do_wake;
      unsigned long i;

      for (i = 0; i < num_tasks; i++)
	{
	  struct gomp_task *task
	    = gomp_malloc (sizeof (*task) + arg_size + arg_align - 1);
	  tasks[i] = task;
	  arg = (char *) (((uintptr_t) (task + 1) + arg_align - 1)
			  & ~(uintptr_t) (arg_align - 1));
	  gomp_init_task (task, parent, gomp_icv (false));
	  task->priority = priority;
	  task->kind = GOMP_TASK_UNDEFERRED;
	  task->in_tied_task = parent->in_tied_task;
	  task->taskgroup = taskgroup;
	  thr->task = task;
	  if (cpyfn)
	    {
	      cpyfn (arg, data);
	      task->copy_ctors_done = true;
	    }
	  else
	    memcpy (arg, data, arg_size);
	  ((TYPE *)arg)[0] = start;
	  start += task_step;
	  ((TYPE *)arg)[1] = start;
	  if (i == nfirst)
	    task_step = nfirst_task_step;
	  thr->task = parent;
	  task->kind = GOMP_TASK_WAITING;
	  task->fn = fn;
	  task->fn_data = arg;
	  task->final_task = (flags & GOMP_TASK_FLAG_FINAL) >> 1;
	}
      gomp_mutex_lock (&team->task_lock);
      /* If parallel or taskgroup has been cancelled, don't start new
	 tasks.  */
      if (__builtin_expect (gomp_cancel_var, 0)
	  && cpyfn == NULL)
	{
	  if (gomp_team_barrier_cancelled (&team->barrier))
	    {
	    do_cancel:
	      gomp_mutex_unlock (&team->task_lock);
	      for (i = 0; i < num_tasks; i++)
		{
		  gomp_finish_task (tasks[i]);
		  free (tasks[i]);
		}
	      if ((flags & GOMP_TASK_FLAG_NOGROUP) == 0)
		ialias_call (GOMP_taskgroup_end) ();
	      return;
	    }
	  if (taskgroup)
	    {
	      if (taskgroup->cancelled)
		goto do_cancel;
	      if (taskgroup->workshare
		  && taskgroup->prev
		  && taskgroup->prev->cancelled)
		goto do_cancel;
	    }
	}
      if (taskgroup)
	taskgroup->num_children += num_tasks;
      for (i = 0; i < num_tasks; i++)
	{
	  struct gomp_task *task = tasks[i];
	  priority_queue_insert (PQ_CHILDREN, &parent->children_queue,
				 task, priority,
				 PRIORITY_INSERT_BEGIN,
				 /*last_parent_depends_on=*/false,
				 task->parent_depends_on);
	  if (taskgroup)
	    priority_queue_insert (PQ_TASKGROUP, &taskgroup->taskgroup_queue,
				   task, priority, PRIORITY_INSERT_BEGIN,
				   /*last_parent_depends_on=*/false,
				   task->parent_depends_on);
	  priority_queue_insert (PQ_TEAM, &team->task_queue, task, priority,
				 PRIORITY_INSERT_END,
				 /*last_parent_depends_on=*/false,
				 task->parent_depends_on);
	  ++team->task_count;
	  ++team->task_queued_count;
	}
      gomp_team_barrier_set_task_pending (&team->barrier);
      if (team->task_running_count + !parent->in_tied_task
	  < team->nthreads)
	{
	  do_wake = team->nthreads - team->task_running_count
		    - !parent->in_tied_task;
	  if ((unsigned long) do_wake > num_tasks)
	    do_wake = num_tasks;
	}
      else
	do_wake = 0;
      gomp_mutex_unlock (&team->task_lock);
      if (do_wake)
	gomp_team_barrier_wake (&team->barrier, do_wake);
    }
  if ((flags & GOMP_TASK_FLAG_NOGROUP) == 0)
    ialias_call (GOMP_taskgroup_end) ();
}