aboutsummaryrefslogtreecommitdiff
path: root/libgomp/ordered.c
blob: 80af02a63d03e25e494ed7d2e4dbb1622992220d (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
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
/* Copyright (C) 2005-2016 Free Software Foundation, Inc.
   Contributed by Richard Henderson <rth@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 ORDERED construct.  */

#include "libgomp.h"
#include <stdarg.h>
#include <string.h>
#include "doacross.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.
     However, there is an implicit flush on entry to an ordered region,
     so we do need to have a barrier here.  If we were taking a lock
     this could be MEMMODEL_RELEASE since the acquire would be coverd
     by the lock.  */

  __atomic_thread_fence (MEMMODEL_ACQ_REL);
  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)
{
}

/* DOACROSS initialization.  */

#define MAX_COLLAPSED_BITS (__SIZEOF_LONG__ * __CHAR_BIT__)

void
gomp_doacross_init (unsigned ncounts, long *counts, long chunk_size)
{
  struct gomp_thread *thr = gomp_thread ();
  struct gomp_team *team = thr->ts.team;
  struct gomp_work_share *ws = thr->ts.work_share;
  unsigned int i, bits[MAX_COLLAPSED_BITS], num_bits = 0;
  unsigned long ent, num_ents, elt_sz, shift_sz;
  struct gomp_doacross_work_share *doacross;

  if (team == NULL || team->nthreads == 1)
    return;

  for (i = 0; i < ncounts; i++)
    {
      /* If any count is 0, GOMP_doacross_{post,wait} can't be called.  */
      if (counts[i] == 0)
	return;

      if (num_bits <= MAX_COLLAPSED_BITS)
	{
	  unsigned int this_bits;
	  if (counts[i] == 1)
	    this_bits = 1;
	  else
	    this_bits = __SIZEOF_LONG__ * __CHAR_BIT__
			- __builtin_clzl (counts[i] - 1);
	  if (num_bits + this_bits <= MAX_COLLAPSED_BITS)
	    {
	      bits[i] = this_bits;
	      num_bits += this_bits;
	    }
	  else
	    num_bits = MAX_COLLAPSED_BITS + 1;
	}
    }

  if (ws->sched == GFS_STATIC)
    num_ents = team->nthreads;
  else if (ws->sched == GFS_GUIDED)
    num_ents = counts[0];
  else
    num_ents = (counts[0] - 1) / chunk_size + 1;
  if (num_bits <= MAX_COLLAPSED_BITS)
    {
      elt_sz = sizeof (unsigned long);
      shift_sz = ncounts * sizeof (unsigned int);
    }
  else
    {
      elt_sz = sizeof (unsigned long) * ncounts;
      shift_sz = 0;
    }
  elt_sz = (elt_sz + 63) & ~63UL;

  doacross = gomp_malloc (sizeof (*doacross) + 63 + num_ents * elt_sz
			  + shift_sz);
  doacross->chunk_size = chunk_size;
  doacross->elt_sz = elt_sz;
  doacross->ncounts = ncounts;
  doacross->flattened = false;
  doacross->array = (unsigned char *)
		    ((((uintptr_t) (doacross + 1)) + 63 + shift_sz)
		     & ~(uintptr_t) 63);
  if (num_bits <= MAX_COLLAPSED_BITS)
    {
      unsigned int shift_count = 0;
      doacross->flattened = true;
      for (i = ncounts; i > 0; i--)
	{
	  doacross->shift_counts[i - 1] = shift_count;
	  shift_count += bits[i - 1];
	}
      for (ent = 0; ent < num_ents; ent++)
	*(unsigned long *) (doacross->array + ent * elt_sz) = 0;
    }
  else
    for (ent = 0; ent < num_ents; ent++)
      memset (doacross->array + ent * elt_sz, '\0',
	      sizeof (unsigned long) * ncounts);
  if (ws->sched == GFS_STATIC && chunk_size == 0)
    {
      unsigned long q = counts[0] / num_ents;
      unsigned long t = counts[0] % num_ents;
      doacross->boundary = t * (q + 1);
      doacross->q = q;
      doacross->t = t;
    }
  ws->doacross = doacross;
}

/* DOACROSS POST operation.  */

void
GOMP_doacross_post (long *counts)
{
  struct gomp_thread *thr = gomp_thread ();
  struct gomp_work_share *ws = thr->ts.work_share;
  struct gomp_doacross_work_share *doacross = ws->doacross;
  unsigned long ent;
  unsigned int i;

  if (__builtin_expect (doacross == NULL, 0))
    {
      __sync_synchronize ();
      return;
    }

  if (__builtin_expect (ws->sched == GFS_STATIC, 1))
    ent = thr->ts.team_id;
  else if (ws->sched == GFS_GUIDED)
    ent = counts[0];
  else
    ent = counts[0] / doacross->chunk_size;
  unsigned long *array = (unsigned long *) (doacross->array
					    + ent * doacross->elt_sz);

  if (__builtin_expect (doacross->flattened, 1))
    {
      unsigned long flattened
	= (unsigned long) counts[0] << doacross->shift_counts[0];

      for (i = 1; i < doacross->ncounts; i++)
	flattened |= (unsigned long) counts[i]
		     << doacross->shift_counts[i];
      flattened++;
      if (flattened == __atomic_load_n (array, MEMMODEL_ACQUIRE))
	__atomic_thread_fence (MEMMODEL_RELEASE);
      else
	__atomic_store_n (array, flattened, MEMMODEL_RELEASE);
      return;
    }

  __atomic_thread_fence (MEMMODEL_ACQUIRE);
  for (i = doacross->ncounts; i-- > 0; )
    {
      if (counts[i] + 1UL != __atomic_load_n (&array[i], MEMMODEL_RELAXED))
	__atomic_store_n (&array[i], counts[i] + 1UL, MEMMODEL_RELEASE);
    }
}

/* DOACROSS WAIT operation.  */

void
GOMP_doacross_wait (long first, ...)
{
  struct gomp_thread *thr = gomp_thread ();
  struct gomp_work_share *ws = thr->ts.work_share;
  struct gomp_doacross_work_share *doacross = ws->doacross;
  va_list ap;
  unsigned long ent;
  unsigned int i;

  if (__builtin_expect (doacross == NULL, 0))
    {
      __sync_synchronize ();
      return;
    }

  if (__builtin_expect (ws->sched == GFS_STATIC, 1))
    {
      if (ws->chunk_size == 0)
	{
	  if (first < doacross->boundary)
	    ent = first / (doacross->q + 1);
	  else
	    ent = (first - doacross->boundary) / doacross->q
		  + doacross->t;
	}
      else
	ent = first / ws->chunk_size % thr->ts.team->nthreads;
    }
  else if (ws->sched == GFS_GUIDED)
    ent = first;
  else
    ent = first / doacross->chunk_size;
  unsigned long *array = (unsigned long *) (doacross->array
					    + ent * doacross->elt_sz);

  if (__builtin_expect (doacross->flattened, 1))
    {
      unsigned long flattened
	= (unsigned long) first << doacross->shift_counts[0];
      unsigned long cur;

      va_start (ap, first);
      for (i = 1; i < doacross->ncounts; i++)
	flattened |= (unsigned long) va_arg (ap, long)
		     << doacross->shift_counts[i];
      cur = __atomic_load_n (array, MEMMODEL_ACQUIRE);
      if (flattened < cur)
	{
	  __atomic_thread_fence (MEMMODEL_RELEASE);
	  va_end (ap);
	  return;
	}
      doacross_spin (array, flattened, cur);
      __atomic_thread_fence (MEMMODEL_RELEASE);
      va_end (ap);
      return;
    }

  do
    {
      va_start (ap, first);
      for (i = 0; i < doacross->ncounts; i++)
	{
	  unsigned long thisv
	    = (unsigned long) (i ? va_arg (ap, long) : first) + 1;
	  unsigned long cur = __atomic_load_n (&array[i], MEMMODEL_RELAXED);
	  if (thisv < cur)
	    {
	      i = doacross->ncounts;
	      break;
	    }
	  if (thisv > cur)
	    break;
	}
      va_end (ap);
      if (i == doacross->ncounts)
	break;
      cpu_relax ();
    }
  while (1);
  __sync_synchronize ();
}

typedef unsigned long long gomp_ull;

void
gomp_doacross_ull_init (unsigned ncounts, gomp_ull *counts, gomp_ull chunk_size)
{
  struct gomp_thread *thr = gomp_thread ();
  struct gomp_team *team = thr->ts.team;
  struct gomp_work_share *ws = thr->ts.work_share;
  unsigned int i, bits[MAX_COLLAPSED_BITS], num_bits = 0;
  unsigned long ent, num_ents, elt_sz, shift_sz;
  struct gomp_doacross_work_share *doacross;

  if (team == NULL || team->nthreads == 1)
    return;

  for (i = 0; i < ncounts; i++)
    {
      /* If any count is 0, GOMP_doacross_{post,wait} can't be called.  */
      if (counts[i] == 0)
	return;

      if (num_bits <= MAX_COLLAPSED_BITS)
	{
	  unsigned int this_bits;
	  if (counts[i] == 1)
	    this_bits = 1;
	  else
	    this_bits = __SIZEOF_LONG_LONG__ * __CHAR_BIT__
			- __builtin_clzll (counts[i] - 1);
	  if (num_bits + this_bits <= MAX_COLLAPSED_BITS)
	    {
	      bits[i] = this_bits;
	      num_bits += this_bits;
	    }
	  else
	    num_bits = MAX_COLLAPSED_BITS + 1;
	}
    }

  if (ws->sched == GFS_STATIC)
    num_ents = team->nthreads;
  else if (ws->sched == GFS_GUIDED)
    num_ents = counts[0];
  else
    num_ents = (counts[0] - 1) / chunk_size + 1;
  if (num_bits <= MAX_COLLAPSED_BITS)
    {
      elt_sz = sizeof (unsigned long);
      shift_sz = ncounts * sizeof (unsigned int);
    }
  else
    {
      if (sizeof (gomp_ull) == sizeof (unsigned long))
	elt_sz = sizeof (gomp_ull) * ncounts;
      else if (sizeof (gomp_ull) == 2 * sizeof (unsigned long))
	elt_sz = sizeof (unsigned long) * 2 * ncounts;
      else
	abort ();
      shift_sz = 0;
    }
  elt_sz = (elt_sz + 63) & ~63UL;

  doacross = gomp_malloc (sizeof (*doacross) + 63 + num_ents * elt_sz
			  + shift_sz);
  doacross->chunk_size_ull = chunk_size;
  doacross->elt_sz = elt_sz;
  doacross->ncounts = ncounts;
  doacross->flattened = false;
  doacross->boundary = 0;
  doacross->array = (unsigned char *)
		    ((((uintptr_t) (doacross + 1)) + 63 + shift_sz)
		     & ~(uintptr_t) 63);
  if (num_bits <= MAX_COLLAPSED_BITS)
    {
      unsigned int shift_count = 0;
      doacross->flattened = true;
      for (i = ncounts; i > 0; i--)
	{
	  doacross->shift_counts[i - 1] = shift_count;
	  shift_count += bits[i - 1];
	}
      for (ent = 0; ent < num_ents; ent++)
	*(unsigned long *) (doacross->array + ent * elt_sz) = 0;
    }
  else
    for (ent = 0; ent < num_ents; ent++)
      memset (doacross->array + ent * elt_sz, '\0',
	      sizeof (unsigned long) * ncounts);
  if (ws->sched == GFS_STATIC && chunk_size == 0)
    {
      gomp_ull q = counts[0] / num_ents;
      gomp_ull t = counts[0] % num_ents;
      doacross->boundary_ull = t * (q + 1);
      doacross->q_ull = q;
      doacross->t = t;
    }
  ws->doacross = doacross;
}

/* DOACROSS POST operation.  */

void
GOMP_doacross_ull_post (gomp_ull *counts)
{
  struct gomp_thread *thr = gomp_thread ();
  struct gomp_work_share *ws = thr->ts.work_share;
  struct gomp_doacross_work_share *doacross = ws->doacross;
  unsigned long ent;
  unsigned int i;

  if (__builtin_expect (doacross == NULL, 0))
    {
      __sync_synchronize ();
      return;
    }

  if (__builtin_expect (ws->sched == GFS_STATIC, 1))
    ent = thr->ts.team_id;
  else if (ws->sched == GFS_GUIDED)
    ent = counts[0];
  else
    ent = counts[0] / doacross->chunk_size_ull;

  if (__builtin_expect (doacross->flattened, 1))
    {
      unsigned long *array = (unsigned long *) (doacross->array
			      + ent * doacross->elt_sz);
      gomp_ull flattened
	= counts[0] << doacross->shift_counts[0];

      for (i = 1; i < doacross->ncounts; i++)
	flattened |= counts[i] << doacross->shift_counts[i];
      flattened++;
      if (flattened == __atomic_load_n (array, MEMMODEL_ACQUIRE))
	__atomic_thread_fence (MEMMODEL_RELEASE);
      else
	__atomic_store_n (array, flattened, MEMMODEL_RELEASE);
      return;
    }

  __atomic_thread_fence (MEMMODEL_ACQUIRE);
  if (sizeof (gomp_ull) == sizeof (unsigned long))
    {
      gomp_ull *array = (gomp_ull *) (doacross->array
				      + ent * doacross->elt_sz);

      for (i = doacross->ncounts; i-- > 0; )
	{
	  if (counts[i] + 1UL != __atomic_load_n (&array[i], MEMMODEL_RELAXED))
	    __atomic_store_n (&array[i], counts[i] + 1UL, MEMMODEL_RELEASE);
	}
    }
  else
    {
      unsigned long *array = (unsigned long *) (doacross->array
						+ ent * doacross->elt_sz);

      for (i = doacross->ncounts; i-- > 0; )
	{
	  gomp_ull cull = counts[i] + 1UL;
	  unsigned long c = (unsigned long) cull;
	  if (c != __atomic_load_n (&array[2 * i + 1], MEMMODEL_RELAXED))
	    __atomic_store_n (&array[2 * i + 1], c, MEMMODEL_RELEASE);
	  c = cull >> (__SIZEOF_LONG_LONG__ * __CHAR_BIT__ / 2);
	  if (c != __atomic_load_n (&array[2 * i], MEMMODEL_RELAXED))
	    __atomic_store_n (&array[2 * i], c, MEMMODEL_RELEASE);
	}
    }
}

/* DOACROSS WAIT operation.  */

void
GOMP_doacross_ull_wait (gomp_ull first, ...)
{
  struct gomp_thread *thr = gomp_thread ();
  struct gomp_work_share *ws = thr->ts.work_share;
  struct gomp_doacross_work_share *doacross = ws->doacross;
  va_list ap;
  unsigned long ent;
  unsigned int i;

  if (__builtin_expect (doacross == NULL, 0))
    {
      __sync_synchronize ();
      return;
    }

  if (__builtin_expect (ws->sched == GFS_STATIC, 1))
    {
      if (ws->chunk_size_ull == 0)
	{
	  if (first < doacross->boundary_ull)
	    ent = first / (doacross->q_ull + 1);
	  else
	    ent = (first - doacross->boundary_ull) / doacross->q_ull
		  + doacross->t;
	}
      else
	ent = first / ws->chunk_size_ull % thr->ts.team->nthreads;
    }
  else if (ws->sched == GFS_GUIDED)
    ent = first;
  else
    ent = first / doacross->chunk_size_ull;

  if (__builtin_expect (doacross->flattened, 1))
    {
      unsigned long *array = (unsigned long *) (doacross->array
						+ ent * doacross->elt_sz);
      gomp_ull flattened = first << doacross->shift_counts[0];
      unsigned long cur;

      va_start (ap, first);
      for (i = 1; i < doacross->ncounts; i++)
	flattened |= va_arg (ap, gomp_ull)
		     << doacross->shift_counts[i];
      cur = __atomic_load_n (array, MEMMODEL_ACQUIRE);
      if (flattened < cur)
	{
	  __atomic_thread_fence (MEMMODEL_RELEASE);
	  va_end (ap);
	  return;
	}
      doacross_spin (array, flattened, cur);
      __atomic_thread_fence (MEMMODEL_RELEASE);
      va_end (ap);
      return;
    }

  if (sizeof (gomp_ull) == sizeof (unsigned long))
    {
      gomp_ull *array = (gomp_ull *) (doacross->array
				      + ent * doacross->elt_sz);
      do
	{
	  va_start (ap, first);
	  for (i = 0; i < doacross->ncounts; i++)
	    {
	      gomp_ull thisv
		= (i ? va_arg (ap, gomp_ull) : first) + 1;
	      gomp_ull cur = __atomic_load_n (&array[i], MEMMODEL_RELAXED);
	      if (thisv < cur)
		{
		  i = doacross->ncounts;
		  break;
		}
	      if (thisv > cur)
		break;
	    }
	  va_end (ap);
	  if (i == doacross->ncounts)
	    break;
	  cpu_relax ();
	}
      while (1);
    }
  else
    {
      unsigned long *array = (unsigned long *) (doacross->array
						+ ent * doacross->elt_sz);
      do
	{
	  va_start (ap, first);
	  for (i = 0; i < doacross->ncounts; i++)
	    {
	      gomp_ull thisv
		= (i ? va_arg (ap, gomp_ull) : first) + 1;
	      unsigned long t
		= thisv >> (__SIZEOF_LONG_LONG__ * __CHAR_BIT__ / 2);
	      unsigned long cur
		= __atomic_load_n (&array[2 * i], MEMMODEL_RELAXED);
	      if (t < cur)
		{
		  i = doacross->ncounts;
		  break;
		}
	      if (t > cur)
		break;
	      t = thisv;
	      cur = __atomic_load_n (&array[2 * i + 1], MEMMODEL_RELAXED);
	      if (t < cur)
		{
		  i = doacross->ncounts;
		  break;
		}
	      if (t > cur)
		break;
	    }
	  va_end (ap);
	  if (i == doacross->ncounts)
	    break;
	  cpu_relax ();
	}
      while (1);
    }
  __sync_synchronize ();
}