summaryrefslogtreecommitdiff
path: root/gcc/graphite-dependences.c
blob: 366588b359537c3f67158777587182b25c544695 (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
/* Data dependence analysis for Graphite.
   Copyright (C) 2009-2013 Free Software Foundation, Inc.
   Contributed by Sebastian Pop <sebastian.pop@amd.com> and
   Konrad Trifunovic <konrad.trifunovic@inria.fr>.

This file is part of GCC.

GCC 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.

GCC 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.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#include "config.h"

#ifdef HAVE_cloog
#include <isl/set.h>
#include <isl/map.h>
#include <isl/union_map.h>
#include <isl/flow.h>
#include <isl/constraint.h>
#include <cloog/cloog.h>
#include <cloog/isl/domain.h>
#endif

#include "system.h"
#include "coretypes.h"
#include "tree-flow.h"
#include "tree-pass.h"
#include "cfgloop.h"
#include "tree-chrec.h"
#include "tree-data-ref.h"
#include "tree-scalar-evolution.h"
#include "sese.h"

#ifdef HAVE_cloog
#include "graphite-poly.h"
#include "graphite-htab.h"

/* Add the constraints from the set S to the domain of MAP.  */

static isl_map *
constrain_domain (isl_map *map, isl_set *s)
{
  isl_space *d = isl_map_get_space (map);
  isl_id *id = isl_space_get_tuple_id (d, isl_dim_in);

  s = isl_set_set_tuple_id (s, id);
  isl_space_free (d);
  return isl_map_intersect_domain (map, s);
}

/* Constrain pdr->accesses with pdr->extent and pbb->domain.  */

static isl_map *
add_pdr_constraints (poly_dr_p pdr, poly_bb_p pbb)
{
  isl_map *x = isl_map_intersect_range (isl_map_copy (pdr->accesses),
					isl_set_copy (pdr->extent));
  x = constrain_domain (x, isl_set_copy (pbb->domain));
  return x;
}

/* Returns all the memory reads in SCOP.  */

static isl_union_map *
scop_get_reads (scop_p scop, vec<poly_bb_p> pbbs)
{
  int i, j;
  poly_bb_p pbb;
  poly_dr_p pdr;
  isl_space *space = isl_set_get_space (scop->context);
  isl_union_map *res = isl_union_map_empty (space);

  FOR_EACH_VEC_ELT (pbbs, i, pbb)
    {
      FOR_EACH_VEC_ELT (PBB_DRS (pbb), j, pdr)
	if (pdr_read_p (pdr))
	  res = isl_union_map_add_map (res, add_pdr_constraints (pdr, pbb));
    }

  return res;
}

/* Returns all the memory must writes in SCOP.  */

static isl_union_map *
scop_get_must_writes (scop_p scop, vec<poly_bb_p> pbbs)
{
  int i, j;
  poly_bb_p pbb;
  poly_dr_p pdr;
  isl_space *space = isl_set_get_space (scop->context);
  isl_union_map *res = isl_union_map_empty (space);

  FOR_EACH_VEC_ELT (pbbs, i, pbb)
    {
      FOR_EACH_VEC_ELT (PBB_DRS (pbb), j, pdr)
	if (pdr_write_p (pdr))
	  res = isl_union_map_add_map (res, add_pdr_constraints (pdr, pbb));
    }

  return res;
}

/* Returns all the memory may writes in SCOP.  */

static isl_union_map *
scop_get_may_writes (scop_p scop, vec<poly_bb_p> pbbs)
{
  int i, j;
  poly_bb_p pbb;
  poly_dr_p pdr;
  isl_space *space = isl_set_get_space (scop->context);
  isl_union_map *res = isl_union_map_empty (space);

  FOR_EACH_VEC_ELT (pbbs, i, pbb)
    {
      FOR_EACH_VEC_ELT (PBB_DRS (pbb), j, pdr)
	if (pdr_may_write_p (pdr))
	  res = isl_union_map_add_map (res, add_pdr_constraints (pdr, pbb));
    }

  return res;
}

/* Returns all the original schedules in SCOP.  */

static isl_union_map *
scop_get_original_schedule (scop_p scop, vec<poly_bb_p> pbbs)
{
  int i;
  poly_bb_p pbb;
  isl_space *space = isl_set_get_space (scop->context);
  isl_union_map *res = isl_union_map_empty (space);

  FOR_EACH_VEC_ELT (pbbs, i, pbb)
    {
      res = isl_union_map_add_map
	(res, constrain_domain (isl_map_copy (pbb->schedule),
				isl_set_copy (pbb->domain)));
    }

  return res;
}

/* Returns all the transformed schedules in SCOP.  */

static isl_union_map *
scop_get_transformed_schedule (scop_p scop, vec<poly_bb_p> pbbs)
{
  int i;
  poly_bb_p pbb;
  isl_space *space = isl_set_get_space (scop->context);
  isl_union_map *res = isl_union_map_empty (space);

  FOR_EACH_VEC_ELT (pbbs, i, pbb)
    {
      res = isl_union_map_add_map
	(res, constrain_domain (isl_map_copy (pbb->transformed),
				isl_set_copy (pbb->domain)));
    }

  return res;
}

/* Helper function used on each MAP of a isl_union_map.  Computes the
   maximal output dimension.  */

static int
max_number_of_out_dimensions (__isl_take isl_map *map, void *user)
{
  int global_max = *((int *) user);
  isl_space *space = isl_map_get_space (map);
  int nb_out = isl_space_dim (space, isl_dim_out);

  if (global_max < nb_out)
    *((int *) user) = nb_out;

  isl_map_free (map);
  isl_space_free (space);
  return 0;
}

/* Extends the output dimension of MAP to MAX dimensions.  */

static __isl_give isl_map *
extend_map (__isl_take isl_map *map, int max)
{
  isl_space *space = isl_map_get_space (map);
  int n = isl_space_dim (space, isl_dim_out);

  isl_space_free (space);
  return isl_map_add_dims (map, isl_dim_out, max - n);
}

/* Structure used to pass parameters to extend_schedule_1.  */

struct extend_schedule_str {
  int max;
  isl_union_map *umap;
};

/* Helper function for extend_schedule.  */

static int
extend_schedule_1 (__isl_take isl_map *map, void *user)
{
  struct extend_schedule_str *str = (struct extend_schedule_str *) user;
  str->umap = isl_union_map_add_map (str->umap, extend_map (map, str->max));
  return 0;
}

/* Return a relation that has uniform output dimensions.  */

__isl_give isl_union_map *
extend_schedule (__isl_take isl_union_map *x)
{
  int max = 0;
  int res;
  struct extend_schedule_str str;

  res = isl_union_map_foreach_map (x, max_number_of_out_dimensions, (void *) &max);
  gcc_assert (res == 0);

  str.max = max;
  str.umap = isl_union_map_empty (isl_union_map_get_space (x));
  res = isl_union_map_foreach_map (x, extend_schedule_1, (void *) &str);
  gcc_assert (res == 0);

  isl_union_map_free (x);
  return str.umap;
}

/* Applies SCHEDULE to the in and out dimensions of the dependences
   DEPS and return the resulting relation.  */

static isl_map *
apply_schedule_on_deps (__isl_keep isl_union_map *schedule,
			__isl_keep isl_union_map *deps)
{
  isl_map *x;
  isl_union_map *ux, *trans;

  trans = isl_union_map_copy (schedule);
  trans = extend_schedule (trans);
  ux = isl_union_map_copy (deps);
  ux = isl_union_map_apply_domain (ux, isl_union_map_copy (trans));
  ux = isl_union_map_apply_range (ux, trans);
  x = isl_map_from_union_map (ux);

  return x;
}

/* Return true when SCHEDULE does not violate the data DEPS: that is
   when the intersection of LEX with the DEPS transformed by SCHEDULE
   is empty.  LEX is the relation in which the outputs occur before
   the inputs.  */

static bool
no_violations (__isl_keep isl_union_map *schedule,
	       __isl_keep isl_union_map *deps)
{
  bool res;
  isl_space *space;
  isl_map *lex, *x;

  if (isl_union_map_is_empty (deps))
    return true;

  x = apply_schedule_on_deps (schedule, deps);
  space = isl_map_get_space (x);
  space = isl_space_range (space);
  lex = isl_map_lex_ge (space);
  x = isl_map_intersect (x, lex);
  res = isl_map_is_empty (x);

  isl_map_free (x);
  return res;
}

/* Return true when DEPS is non empty and the intersection of LEX with
   the DEPS transformed by SCHEDULE is non empty.  LEX is the relation
   in which all the inputs before DEPTH occur at the same time as the
   output, and the input at DEPTH occurs before output.  */

static bool
carries_deps (__isl_keep isl_union_map *schedule,
	      __isl_keep isl_union_map *deps,
	      int depth)
{
  bool res;
  int idx, i;
  isl_space *space;
  isl_map *lex, *x;
  isl_constraint *ineq;

  if (isl_union_map_is_empty (deps))
    return false;

  x = apply_schedule_on_deps (schedule, deps);
  space = isl_map_get_space (x);
  space = isl_space_range (space);
  lex = isl_map_lex_le (space);
  space = isl_map_get_space (x);
  ineq = isl_inequality_alloc (isl_local_space_from_space (space));

  idx = 2 * depth + 1;
  for (i = 0; i < idx; i++)
    lex = isl_map_equate (lex, isl_dim_in, i, isl_dim_out, i);

  /* in + 1 <= out  */
  ineq = isl_constraint_set_coefficient_si (ineq, isl_dim_out, idx, 1);
  ineq = isl_constraint_set_coefficient_si (ineq, isl_dim_in, idx, -1);
  ineq = isl_constraint_set_constant_si (ineq, -1);
  lex = isl_map_add_constraint (lex, ineq);
  x = isl_map_intersect (x, lex);
  res = !isl_map_is_empty (x);

  isl_map_free (x);
  return res;
}

/* Subtract from the RAW, WAR, and WAW dependences those relations
   that have been marked as belonging to an associative commutative
   reduction.  */

static void
subtract_commutative_associative_deps (scop_p scop,
				       vec<poly_bb_p> pbbs,
				       isl_union_map *original,
				       isl_union_map **must_raw,
				       isl_union_map **may_raw,
				       isl_union_map **must_raw_no_source,
				       isl_union_map **may_raw_no_source,
				       isl_union_map **must_war,
				       isl_union_map **may_war,
				       isl_union_map **must_war_no_source,
				       isl_union_map **may_war_no_source,
				       isl_union_map **must_waw,
				       isl_union_map **may_waw,
				       isl_union_map **must_waw_no_source,
				       isl_union_map **may_waw_no_source)
{
  int i, j;
  poly_bb_p pbb;
  poly_dr_p pdr;
  isl_space *space = isl_set_get_space (scop->context);

  FOR_EACH_VEC_ELT (pbbs, i, pbb)
    if (PBB_IS_REDUCTION (pbb))
      {
	int res;
	isl_union_map *r = isl_union_map_empty (isl_space_copy (space));
	isl_union_map *must_w = isl_union_map_empty (isl_space_copy (space));
	isl_union_map *may_w = isl_union_map_empty (isl_space_copy (space));
	isl_union_map *all_w;
	isl_union_map *empty;
	isl_union_map *x_must_raw;
	isl_union_map *x_may_raw;
	isl_union_map *x_must_raw_no_source;
	isl_union_map *x_may_raw_no_source;
	isl_union_map *x_must_war;
	isl_union_map *x_may_war;
	isl_union_map *x_must_war_no_source;
	isl_union_map *x_may_war_no_source;
	isl_union_map *x_must_waw;
	isl_union_map *x_may_waw;
	isl_union_map *x_must_waw_no_source;
	isl_union_map *x_may_waw_no_source;

	FOR_EACH_VEC_ELT (PBB_DRS (pbb), j, pdr)
	  if (pdr_read_p (pdr))
	    r = isl_union_map_add_map (r, add_pdr_constraints (pdr, pbb));

	FOR_EACH_VEC_ELT (PBB_DRS (pbb), j, pdr)
	  if (pdr_write_p (pdr))
	    must_w = isl_union_map_add_map (must_w,
					    add_pdr_constraints (pdr, pbb));

	FOR_EACH_VEC_ELT (PBB_DRS (pbb), j, pdr)
	  if (pdr_may_write_p (pdr))
	    may_w = isl_union_map_add_map (may_w,
					   add_pdr_constraints (pdr, pbb));

	all_w = isl_union_map_union
	  (isl_union_map_copy (must_w), isl_union_map_copy (may_w));
	empty = isl_union_map_empty (isl_union_map_get_space (all_w));

	res = isl_union_map_compute_flow (isl_union_map_copy (r),
					  isl_union_map_copy (must_w),
					  isl_union_map_copy (may_w),
					  isl_union_map_copy (original),
					  &x_must_raw, &x_may_raw,
					  &x_must_raw_no_source,
					  &x_may_raw_no_source);
	gcc_assert (res == 0);
	res = isl_union_map_compute_flow (isl_union_map_copy (all_w),
					  r, empty,
					  isl_union_map_copy (original),
					  &x_must_war, &x_may_war,
					  &x_must_war_no_source,
					  &x_may_war_no_source);
	gcc_assert (res == 0);
	res = isl_union_map_compute_flow (all_w, must_w, may_w,
					  isl_union_map_copy (original),
					  &x_must_waw, &x_may_waw,
					  &x_must_waw_no_source,
					  &x_may_waw_no_source);
	gcc_assert (res == 0);

	*must_raw = isl_union_map_subtract (*must_raw, x_must_raw);
	*may_raw = isl_union_map_subtract (*may_raw, x_may_raw);
	*must_raw_no_source = isl_union_map_subtract (*must_raw_no_source,
						      x_must_raw_no_source);
	*may_raw_no_source = isl_union_map_subtract (*may_raw_no_source,
						     x_may_raw_no_source);
	*must_war = isl_union_map_subtract (*must_war, x_must_war);
	*may_war = isl_union_map_subtract (*may_war, x_may_war);
	*must_war_no_source = isl_union_map_subtract (*must_war_no_source,
						      x_must_war_no_source);
	*may_war_no_source = isl_union_map_subtract (*may_war_no_source,
						     x_may_war_no_source);
	*must_waw = isl_union_map_subtract (*must_waw, x_must_waw);
	*may_waw = isl_union_map_subtract (*may_waw, x_may_waw);
	*must_waw_no_source = isl_union_map_subtract (*must_waw_no_source,
						      x_must_waw_no_source);
	*may_waw_no_source = isl_union_map_subtract (*may_waw_no_source,
						     x_may_waw_no_source);
      }

  isl_union_map_free (original);
  isl_space_free (space);
}

/* Compute the original data dependences in SCOP for all the reads and
   writes in PBBS.  */

void
compute_deps (scop_p scop, vec<poly_bb_p> pbbs,
	      isl_union_map **must_raw,
	      isl_union_map **may_raw,
	      isl_union_map **must_raw_no_source,
	      isl_union_map **may_raw_no_source,
	      isl_union_map **must_war,
	      isl_union_map **may_war,
	      isl_union_map **must_war_no_source,
	      isl_union_map **may_war_no_source,
	      isl_union_map **must_waw,
	      isl_union_map **may_waw,
	      isl_union_map **must_waw_no_source,
	      isl_union_map **may_waw_no_source)
{
  isl_union_map *reads = scop_get_reads (scop, pbbs);
  isl_union_map *must_writes = scop_get_must_writes (scop, pbbs);
  isl_union_map *may_writes = scop_get_may_writes (scop, pbbs);
  isl_union_map *all_writes = isl_union_map_union
    (isl_union_map_copy (must_writes), isl_union_map_copy (may_writes));
  isl_space *space = isl_union_map_get_space (all_writes);
  isl_union_map *empty = isl_union_map_empty (space);
  isl_union_map *original = scop_get_original_schedule (scop, pbbs);
  int res;

  res = isl_union_map_compute_flow (isl_union_map_copy (reads),
				    isl_union_map_copy (must_writes),
				    isl_union_map_copy (may_writes),
				    isl_union_map_copy (original),
				    must_raw, may_raw, must_raw_no_source,
				    may_raw_no_source);
  gcc_assert (res == 0);
  res = isl_union_map_compute_flow (isl_union_map_copy (all_writes),
				    reads, empty,
				    isl_union_map_copy (original),
				    must_war, may_war, must_war_no_source,
				    may_war_no_source);
  gcc_assert (res == 0);
  res = isl_union_map_compute_flow (all_writes, must_writes, may_writes,
				    isl_union_map_copy (original),
				    must_waw, may_waw, must_waw_no_source,
				    may_waw_no_source);
  gcc_assert (res == 0);

  subtract_commutative_associative_deps
    (scop, pbbs, original,
     must_raw, may_raw, must_raw_no_source, may_raw_no_source,
     must_war, may_war, must_war_no_source, may_war_no_source,
     must_waw, may_waw, must_waw_no_source, may_waw_no_source);
}

/* Given a TRANSFORM, check whether it respects the original
   dependences in SCOP.  Returns true when TRANSFORM is a safe
   transformation.  */

static bool
transform_is_safe (scop_p scop, isl_union_map *transform)
{
  bool res;

  if (!scop->must_raw)
    compute_deps (scop, SCOP_BBS (scop),
		  &scop->must_raw, &scop->may_raw,
		  &scop->must_raw_no_source, &scop->may_raw_no_source,
		  &scop->must_war, &scop->may_war,
		  &scop->must_war_no_source, &scop->may_war_no_source,
		  &scop->must_waw, &scop->may_waw,
		  &scop->must_waw_no_source, &scop->may_waw_no_source);

  res = (no_violations (transform, scop->must_raw)
	 && no_violations (transform, scop->may_raw)
	 && no_violations (transform, scop->must_war)
	 && no_violations (transform, scop->may_war)
	 && no_violations (transform, scop->must_waw)
	 && no_violations (transform, scop->may_waw));

  isl_union_map_free (transform);
  return res;
}

/* Return true when the SCOP transformed schedule is correct.  */

bool
graphite_legal_transform (scop_p scop)
{
  int res;
  isl_union_map *transform;

  timevar_push (TV_GRAPHITE_DATA_DEPS);
  transform = scop_get_transformed_schedule (scop, SCOP_BBS (scop));
  res = transform_is_safe (scop, transform);
  timevar_pop (TV_GRAPHITE_DATA_DEPS);

  return res;
}

/* Return true when the loop at DEPTH carries dependences.  BODY is
   the body of the loop.  */

static bool
loop_level_carries_dependences (scop_p scop, vec<poly_bb_p> body,
				int depth)
{
  isl_union_map *transform = scop_get_transformed_schedule (scop, body);
  isl_union_map *must_raw, *may_raw;
  isl_union_map *must_war, *may_war;
  isl_union_map *must_waw, *may_waw;
  int res;

  compute_deps (scop, body,
		&must_raw, &may_raw, NULL, NULL,
		&must_war, &may_war, NULL, NULL,
		&must_waw, &may_waw, NULL, NULL);

  res = (carries_deps (transform, must_raw, depth)
	 || carries_deps (transform, may_raw, depth)
	 || carries_deps (transform, must_war, depth)
	 || carries_deps (transform, may_war, depth)
	 || carries_deps (transform, must_waw, depth)
	 || carries_deps (transform, may_waw, depth));

  isl_union_map_free (transform);
  isl_union_map_free (must_raw);
  isl_union_map_free (may_raw);
  isl_union_map_free (must_war);
  isl_union_map_free (may_war);
  isl_union_map_free (must_waw);
  isl_union_map_free (may_waw);
  return res;
}

/* Returns true when the loop L at level DEPTH is parallel.
   BB_PBB_MAPPING is a map between a basic_block and its related
   poly_bb_p.  */

bool
loop_is_parallel_p (loop_p loop, bb_pbb_htab_type bb_pbb_mapping, int depth)
{
  bool dependences;
  scop_p scop;
  vec<poly_bb_p> body;
  body.create (3);

  timevar_push (TV_GRAPHITE_DATA_DEPS);
  scop = get_loop_body_pbbs (loop, bb_pbb_mapping, &body);
  dependences = loop_level_carries_dependences (scop, body, depth);
  body.release ();
  timevar_pop (TV_GRAPHITE_DATA_DEPS);

  return !dependences;
}

#endif