forked from illumos/gcc
-
Notifications
You must be signed in to change notification settings - Fork 1
/
tree-data-ref.c
2475 lines (2050 loc) · 69.6 KB
/
tree-data-ref.c
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
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/* Data references and dependences detectors.
Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
Contributed by Sebastian Pop <s.pop@laposte.net>
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 2, 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 COPYING. If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA. */
/* This pass walks a given loop structure searching for array
references. The information about the array accesses is recorded
in DATA_REFERENCE structures.
The basic test for determining the dependences is:
given two access functions chrec1 and chrec2 to a same array, and
x and y two vectors from the iteration domain, the same element of
the array is accessed twice at iterations x and y if and only if:
| chrec1 (x) == chrec2 (y).
The goals of this analysis are:
- to determine the independence: the relation between two
independent accesses is qualified with the chrec_known (this
information allows a loop parallelization),
- when two data references access the same data, to qualify the
dependence relation with classic dependence representations:
- distance vectors
- direction vectors
- loop carried level dependence
- polyhedron dependence
or with the chains of recurrences based representation,
- to define a knowledge base for storing the data dependence
information,
- to define an interface to access this data.
Definitions:
- subscript: given two array accesses a subscript is the tuple
composed of the access functions for a given dimension. Example:
Given A[f1][f2][f3] and B[g1][g2][g3], there are three subscripts:
(f1, g1), (f2, g2), (f3, g3).
- Diophantine equation: an equation whose coefficients and
solutions are integer constants, for example the equation
| 3*x + 2*y = 1
has an integer solution x = 1 and y = -1.
References:
- "Advanced Compilation for High Performance Computing" by Randy
Allen and Ken Kennedy.
http://citeseer.ist.psu.edu/goff91practical.html
- "Loop Transformations for Restructuring Compilers - The Foundations"
by Utpal Banerjee.
*/
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "errors.h"
#include "ggc.h"
#include "tree.h"
/* These RTL headers are needed for basic-block.h. */
#include "rtl.h"
#include "basic-block.h"
#include "diagnostic.h"
#include "tree-flow.h"
#include "tree-dump.h"
#include "timevar.h"
#include "cfgloop.h"
#include "tree-chrec.h"
#include "tree-data-ref.h"
#include "tree-scalar-evolution.h"
#include "tree-pass.h"
/* This is the simplest data dependence test: determines whether the
data references A and B access the same array/region. Returns
false when the property is not computable at compile time.
Otherwise return true, and DIFFER_P will record the result. This
utility will not be necessary when alias_sets_conflict_p will be
less conservative. */
bool
array_base_name_differ_p (struct data_reference *a,
struct data_reference *b,
bool *differ_p)
{
tree base_a = DR_BASE_NAME (a);
tree base_b = DR_BASE_NAME (b);
tree ta, tb;
if (!base_a || !base_b)
return false;
ta = TREE_TYPE (base_a);
tb = TREE_TYPE (base_b);
/* Determine if same base. Example: for the array accesses
a[i], b[i] or pointer accesses *a, *b, bases are a, b. */
if (base_a == base_b)
{
*differ_p = false;
return true;
}
/* For pointer based accesses, (*p)[i], (*q)[j], the bases are (*p)
and (*q) */
if (TREE_CODE (base_a) == INDIRECT_REF && TREE_CODE (base_b) == INDIRECT_REF
&& TREE_OPERAND (base_a, 0) == TREE_OPERAND (base_b, 0))
{
*differ_p = false;
return true;
}
/* Record/union based accesses - s.a[i], t.b[j]. bases are s.a,t.b. */
if (TREE_CODE (base_a) == COMPONENT_REF && TREE_CODE (base_b) == COMPONENT_REF
&& TREE_OPERAND (base_a, 0) == TREE_OPERAND (base_b, 0)
&& TREE_OPERAND (base_a, 1) == TREE_OPERAND (base_b, 1))
{
*differ_p = false;
return true;
}
/* Determine if different bases. */
/* At this point we know that base_a != base_b. However, pointer
accesses of the form x=(*p) and y=(*q), whose bases are p and q,
may still be pointing to the same base. In SSAed GIMPLE p and q will
be SSA_NAMES in this case. Therefore, here we check if they are
really two different declarations. */
if (TREE_CODE (base_a) == VAR_DECL && TREE_CODE (base_b) == VAR_DECL)
{
*differ_p = true;
return true;
}
/* Compare two record/union bases s.a and t.b: s != t or (a != b and
s and t are not unions). */
if (TREE_CODE (base_a) == COMPONENT_REF && TREE_CODE (base_b) == COMPONENT_REF
&& ((TREE_CODE (TREE_OPERAND (base_a, 0)) == VAR_DECL
&& TREE_CODE (TREE_OPERAND (base_b, 0)) == VAR_DECL
&& TREE_OPERAND (base_a, 0) != TREE_OPERAND (base_b, 0))
|| (TREE_CODE (TREE_TYPE (TREE_OPERAND (base_a, 0))) == RECORD_TYPE
&& TREE_CODE (TREE_TYPE (TREE_OPERAND (base_b, 0))) == RECORD_TYPE
&& TREE_OPERAND (base_a, 1) != TREE_OPERAND (base_b, 1))))
{
*differ_p = true;
return true;
}
/* Compare a record/union access and an array access. */
if ((TREE_CODE (base_a) == VAR_DECL
&& (TREE_CODE (base_b) == COMPONENT_REF
&& TREE_CODE (TREE_OPERAND (base_b, 0)) == VAR_DECL))
|| (TREE_CODE (base_b) == VAR_DECL
&& (TREE_CODE (base_a) == COMPONENT_REF
&& TREE_CODE (TREE_OPERAND (base_a, 0)) == VAR_DECL)))
{
*differ_p = true;
return true;
}
return false;
}
/* Returns true iff A divides B. */
static inline bool
tree_fold_divides_p (tree type,
tree a,
tree b)
{
/* Determines whether (A == gcd (A, B)). */
return integer_zerop
(fold (build (MINUS_EXPR, type, a, tree_fold_gcd (a, b))));
}
/* Compute the greatest common denominator of two numbers using
Euclid's algorithm. */
static int
gcd (int a, int b)
{
int x, y, z;
x = abs (a);
y = abs (b);
while (x>0)
{
z = y % x;
y = x;
x = z;
}
return (y);
}
/* Returns true iff A divides B. */
static inline bool
int_divides_p (int a, int b)
{
return ((b % a) == 0);
}
/* Dump into FILE all the data references from DATAREFS. */
void
dump_data_references (FILE *file,
varray_type datarefs)
{
unsigned int i;
for (i = 0; i < VARRAY_ACTIVE_SIZE (datarefs); i++)
dump_data_reference (file, VARRAY_GENERIC_PTR (datarefs, i));
}
/* Dump into FILE all the dependence relations from DDR. */
void
dump_data_dependence_relations (FILE *file,
varray_type ddr)
{
unsigned int i;
for (i = 0; i < VARRAY_ACTIVE_SIZE (ddr); i++)
dump_data_dependence_relation (file, VARRAY_GENERIC_PTR (ddr, i));
}
/* Dump function for a DATA_REFERENCE structure. */
void
dump_data_reference (FILE *outf,
struct data_reference *dr)
{
unsigned int i;
fprintf (outf, "(Data Ref: \n stmt: ");
print_generic_stmt (outf, DR_STMT (dr), 0);
fprintf (outf, " ref: ");
print_generic_stmt (outf, DR_REF (dr), 0);
fprintf (outf, " base_name: ");
print_generic_stmt (outf, DR_BASE_NAME (dr), 0);
for (i = 0; i < DR_NUM_DIMENSIONS (dr); i++)
{
fprintf (outf, " Access function %d: ", i);
print_generic_stmt (outf, DR_ACCESS_FN (dr, i), 0);
}
fprintf (outf, ")\n");
}
/* Dump function for a SUBSCRIPT structure. */
void
dump_subscript (FILE *outf, struct subscript *subscript)
{
tree chrec = SUB_CONFLICTS_IN_A (subscript);
fprintf (outf, "\n (subscript \n");
fprintf (outf, " iterations_that_access_an_element_twice_in_A: ");
print_generic_stmt (outf, chrec, 0);
if (chrec == chrec_known)
fprintf (outf, " (no dependence)\n");
else if (chrec_contains_undetermined (chrec))
fprintf (outf, " (don't know)\n");
else
{
tree last_iteration = SUB_LAST_CONFLICT (subscript);
fprintf (outf, " last_conflict: ");
print_generic_stmt (outf, last_iteration, 0);
}
chrec = SUB_CONFLICTS_IN_B (subscript);
fprintf (outf, " iterations_that_access_an_element_twice_in_B: ");
print_generic_stmt (outf, chrec, 0);
if (chrec == chrec_known)
fprintf (outf, " (no dependence)\n");
else if (chrec_contains_undetermined (chrec))
fprintf (outf, " (don't know)\n");
else
{
tree last_iteration = SUB_LAST_CONFLICT (subscript);
fprintf (outf, " last_conflict: ");
print_generic_stmt (outf, last_iteration, 0);
}
fprintf (outf, " (Subscript distance: ");
print_generic_stmt (outf, SUB_DISTANCE (subscript), 0);
fprintf (outf, " )\n");
fprintf (outf, " )\n");
}
/* Dump function for a DATA_DEPENDENCE_RELATION structure. */
void
dump_data_dependence_relation (FILE *outf,
struct data_dependence_relation *ddr)
{
struct data_reference *dra, *drb;
dra = DDR_A (ddr);
drb = DDR_B (ddr);
fprintf (outf, "(Data Dep: \n");
if (DDR_ARE_DEPENDENT (ddr) == chrec_dont_know)
fprintf (outf, " (don't know)\n");
else if (DDR_ARE_DEPENDENT (ddr) == chrec_known)
fprintf (outf, " (no dependence)\n");
else if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE)
{
unsigned int i;
for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++)
{
fprintf (outf, " access_fn_A: ");
print_generic_stmt (outf, DR_ACCESS_FN (dra, i), 0);
fprintf (outf, " access_fn_B: ");
print_generic_stmt (outf, DR_ACCESS_FN (drb, i), 0);
dump_subscript (outf, DDR_SUBSCRIPT (ddr, i));
}
if (DDR_DIST_VECT (ddr))
{
fprintf (outf, " distance_vect: ");
print_lambda_vector (outf, DDR_DIST_VECT (ddr), DDR_SIZE_VECT (ddr));
}
if (DDR_DIR_VECT (ddr))
{
fprintf (outf, " direction_vect: ");
print_lambda_vector (outf, DDR_DIR_VECT (ddr), DDR_SIZE_VECT (ddr));
}
}
fprintf (outf, ")\n");
}
/* Dump function for a DATA_DEPENDENCE_DIRECTION structure. */
void
dump_data_dependence_direction (FILE *file,
enum data_dependence_direction dir)
{
switch (dir)
{
case dir_positive:
fprintf (file, "+");
break;
case dir_negative:
fprintf (file, "-");
break;
case dir_equal:
fprintf (file, "=");
break;
case dir_positive_or_negative:
fprintf (file, "+-");
break;
case dir_positive_or_equal:
fprintf (file, "+=");
break;
case dir_negative_or_equal:
fprintf (file, "-=");
break;
case dir_star:
fprintf (file, "*");
break;
default:
break;
}
}
/* Dumps the distance and direction vectors in FILE. DDRS contains
the dependence relations, and VECT_SIZE is the size of the
dependence vectors, or in other words the number of loops in the
considered nest. */
void
dump_dist_dir_vectors (FILE *file, varray_type ddrs)
{
unsigned int i;
for (i = 0; i < VARRAY_ACTIVE_SIZE (ddrs); i++)
{
struct data_dependence_relation *ddr =
(struct data_dependence_relation *)
VARRAY_GENERIC_PTR (ddrs, i);
if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE
&& DDR_AFFINE_P (ddr))
{
fprintf (file, "DISTANCE_V (");
print_lambda_vector (file, DDR_DIST_VECT (ddr), DDR_SIZE_VECT (ddr));
fprintf (file, ")\n");
fprintf (file, "DIRECTION_V (");
print_lambda_vector (file, DDR_DIR_VECT (ddr), DDR_SIZE_VECT (ddr));
fprintf (file, ")\n");
}
}
fprintf (file, "\n\n");
}
/* Dumps the data dependence relations DDRS in FILE. */
void
dump_ddrs (FILE *file, varray_type ddrs)
{
unsigned int i;
for (i = 0; i < VARRAY_ACTIVE_SIZE (ddrs); i++)
{
struct data_dependence_relation *ddr =
(struct data_dependence_relation *)
VARRAY_GENERIC_PTR (ddrs, i);
dump_data_dependence_relation (file, ddr);
}
fprintf (file, "\n\n");
}
/* Compute the lowest iteration bound for LOOP. It is an
INTEGER_CST. */
static void
compute_estimated_nb_iterations (struct loop *loop)
{
tree estimation;
struct nb_iter_bound *bound, *next;
for (bound = loop->bounds; bound; bound = next)
{
next = bound->next;
estimation = bound->bound;
if (TREE_CODE (estimation) != INTEGER_CST)
continue;
if (loop->estimated_nb_iterations)
{
/* Update only if estimation is smaller. */
if (tree_int_cst_lt (estimation, loop->estimated_nb_iterations))
loop->estimated_nb_iterations = estimation;
}
else
loop->estimated_nb_iterations = estimation;
}
}
/* Estimate the number of iterations from the size of the data and the
access functions. */
static void
estimate_niter_from_size_of_data (struct loop *loop,
tree opnd0,
tree access_fn,
tree stmt)
{
tree estimation;
tree array_size, data_size, element_size;
tree init, step;
init = initial_condition (access_fn);
step = evolution_part_in_loop_num (access_fn, loop->num);
array_size = TYPE_SIZE (TREE_TYPE (opnd0));
element_size = TYPE_SIZE (TREE_TYPE (TREE_TYPE (opnd0)));
if (array_size == NULL_TREE
|| TREE_CODE (array_size) != INTEGER_CST
|| TREE_CODE (element_size) != INTEGER_CST)
return;
data_size = fold (build2 (EXACT_DIV_EXPR, integer_type_node,
array_size, element_size));
if (init != NULL_TREE
&& step != NULL_TREE
&& TREE_CODE (init) == INTEGER_CST
&& TREE_CODE (step) == INTEGER_CST)
{
estimation = fold (build2 (CEIL_DIV_EXPR, integer_type_node,
fold (build2 (MINUS_EXPR, integer_type_node,
data_size, init)), step));
record_estimate (loop, estimation, boolean_true_node, stmt);
}
}
/* Given an ARRAY_REF node REF, records its access functions.
Example: given A[i][3], record in ACCESS_FNS the opnd1 function,
i.e. the constant "3", then recursively call the function on opnd0,
i.e. the ARRAY_REF "A[i]". The function returns the base name:
"A". */
static tree
analyze_array_indexes (struct loop *loop,
varray_type *access_fns,
tree ref, tree stmt)
{
tree opnd0, opnd1;
tree access_fn;
opnd0 = TREE_OPERAND (ref, 0);
opnd1 = TREE_OPERAND (ref, 1);
/* The detection of the evolution function for this data access is
postponed until the dependence test. This lazy strategy avoids
the computation of access functions that are of no interest for
the optimizers. */
access_fn = instantiate_parameters
(loop, analyze_scalar_evolution (loop, opnd1));
if (loop->estimated_nb_iterations == NULL_TREE)
estimate_niter_from_size_of_data (loop, opnd0, access_fn, stmt);
VARRAY_PUSH_TREE (*access_fns, access_fn);
/* Recursively record other array access functions. */
if (TREE_CODE (opnd0) == ARRAY_REF)
return analyze_array_indexes (loop, access_fns, opnd0, stmt);
/* Return the base name of the data access. */
else
return opnd0;
}
/* For a data reference REF contained in the statement STMT, initialize
a DATA_REFERENCE structure, and return it. IS_READ flag has to be
set to true when REF is in the right hand side of an
assignment. */
struct data_reference *
analyze_array (tree stmt, tree ref, bool is_read)
{
struct data_reference *res;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "(analyze_array \n");
fprintf (dump_file, " (ref = ");
print_generic_stmt (dump_file, ref, 0);
fprintf (dump_file, ")\n");
}
res = xmalloc (sizeof (struct data_reference));
DR_STMT (res) = stmt;
DR_REF (res) = ref;
VARRAY_TREE_INIT (DR_ACCESS_FNS (res), 3, "access_fns");
DR_BASE_NAME (res) = analyze_array_indexes
(loop_containing_stmt (stmt), &(DR_ACCESS_FNS (res)), ref, stmt);
DR_IS_READ (res) = is_read;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, ")\n");
return res;
}
/* For a data reference REF contained in the statement STMT, initialize
a DATA_REFERENCE structure, and return it. */
struct data_reference *
init_data_ref (tree stmt,
tree ref,
tree base,
tree access_fn,
bool is_read)
{
struct data_reference *res;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "(init_data_ref \n");
fprintf (dump_file, " (ref = ");
print_generic_stmt (dump_file, ref, 0);
fprintf (dump_file, ")\n");
}
res = xmalloc (sizeof (struct data_reference));
DR_STMT (res) = stmt;
DR_REF (res) = ref;
VARRAY_TREE_INIT (DR_ACCESS_FNS (res), 5, "access_fns");
DR_BASE_NAME (res) = base;
VARRAY_PUSH_TREE (DR_ACCESS_FNS (res), access_fn);
DR_IS_READ (res) = is_read;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, ")\n");
return res;
}
/* Returns true when all the functions of a tree_vec CHREC are the
same. */
static bool
all_chrecs_equal_p (tree chrec)
{
int j;
for (j = 0; j < TREE_VEC_LENGTH (chrec) - 1; j++)
{
tree chrec_j = TREE_VEC_ELT (chrec, j);
tree chrec_j_1 = TREE_VEC_ELT (chrec, j + 1);
if (!integer_zerop
(chrec_fold_minus
(integer_type_node, chrec_j, chrec_j_1)))
return false;
}
return true;
}
/* Determine for each subscript in the data dependence relation DDR
the distance. */
static void
compute_subscript_distance (struct data_dependence_relation *ddr)
{
if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE)
{
unsigned int i;
for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++)
{
tree conflicts_a, conflicts_b, difference;
struct subscript *subscript;
subscript = DDR_SUBSCRIPT (ddr, i);
conflicts_a = SUB_CONFLICTS_IN_A (subscript);
conflicts_b = SUB_CONFLICTS_IN_B (subscript);
if (TREE_CODE (conflicts_a) == TREE_VEC)
{
if (!all_chrecs_equal_p (conflicts_a))
{
SUB_DISTANCE (subscript) = chrec_dont_know;
return;
}
else
conflicts_a = TREE_VEC_ELT (conflicts_a, 0);
}
if (TREE_CODE (conflicts_b) == TREE_VEC)
{
if (!all_chrecs_equal_p (conflicts_b))
{
SUB_DISTANCE (subscript) = chrec_dont_know;
return;
}
else
conflicts_b = TREE_VEC_ELT (conflicts_b, 0);
}
difference = chrec_fold_minus
(integer_type_node, conflicts_b, conflicts_a);
if (evolution_function_is_constant_p (difference))
SUB_DISTANCE (subscript) = difference;
else
SUB_DISTANCE (subscript) = chrec_dont_know;
}
}
}
/* Initialize a ddr. */
struct data_dependence_relation *
initialize_data_dependence_relation (struct data_reference *a,
struct data_reference *b)
{
struct data_dependence_relation *res;
bool differ_p;
res = xmalloc (sizeof (struct data_dependence_relation));
DDR_A (res) = a;
DDR_B (res) = b;
if (a == NULL || b == NULL
|| DR_BASE_NAME (a) == NULL_TREE
|| DR_BASE_NAME (b) == NULL_TREE)
DDR_ARE_DEPENDENT (res) = chrec_dont_know;
/* When the dimensions of A and B differ, we directly initialize
the relation to "there is no dependence": chrec_known. */
else if (DR_NUM_DIMENSIONS (a) != DR_NUM_DIMENSIONS (b)
|| (array_base_name_differ_p (a, b, &differ_p) && differ_p))
DDR_ARE_DEPENDENT (res) = chrec_known;
else
{
unsigned int i;
DDR_AFFINE_P (res) = true;
DDR_ARE_DEPENDENT (res) = NULL_TREE;
DDR_SUBSCRIPTS_VECTOR_INIT (res, DR_NUM_DIMENSIONS (a));
DDR_SIZE_VECT (res) = 0;
DDR_DIST_VECT (res) = NULL;
DDR_DIR_VECT (res) = NULL;
for (i = 0; i < DR_NUM_DIMENSIONS (a); i++)
{
struct subscript *subscript;
subscript = xmalloc (sizeof (struct subscript));
SUB_CONFLICTS_IN_A (subscript) = chrec_dont_know;
SUB_CONFLICTS_IN_B (subscript) = chrec_dont_know;
SUB_LAST_CONFLICT (subscript) = chrec_dont_know;
SUB_DISTANCE (subscript) = chrec_dont_know;
VARRAY_PUSH_GENERIC_PTR (DDR_SUBSCRIPTS (res), subscript);
}
}
return res;
}
/* Set DDR_ARE_DEPENDENT to CHREC and finalize the subscript overlap
description. */
static inline void
finalize_ddr_dependent (struct data_dependence_relation *ddr,
tree chrec)
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "(dependence classified: ");
print_generic_expr (dump_file, chrec, 0);
fprintf (dump_file, ")\n");
}
DDR_ARE_DEPENDENT (ddr) = chrec;
varray_clear (DDR_SUBSCRIPTS (ddr));
}
/* The dependence relation DDR cannot be represented by a distance
vector. */
static inline void
non_affine_dependence_relation (struct data_dependence_relation *ddr)
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "(Dependence relation cannot be represented by distance vector.) \n");
DDR_AFFINE_P (ddr) = false;
}
/* This section contains the classic Banerjee tests. */
/* Returns true iff CHREC_A and CHREC_B are not dependent on any index
variables, i.e., if the ZIV (Zero Index Variable) test is true. */
static inline bool
ziv_subscript_p (tree chrec_a,
tree chrec_b)
{
return (evolution_function_is_constant_p (chrec_a)
&& evolution_function_is_constant_p (chrec_b));
}
/* Returns true iff CHREC_A and CHREC_B are dependent on an index
variable, i.e., if the SIV (Single Index Variable) test is true. */
static bool
siv_subscript_p (tree chrec_a,
tree chrec_b)
{
if ((evolution_function_is_constant_p (chrec_a)
&& evolution_function_is_univariate_p (chrec_b))
|| (evolution_function_is_constant_p (chrec_b)
&& evolution_function_is_univariate_p (chrec_a)))
return true;
if (evolution_function_is_univariate_p (chrec_a)
&& evolution_function_is_univariate_p (chrec_b))
{
switch (TREE_CODE (chrec_a))
{
case POLYNOMIAL_CHREC:
switch (TREE_CODE (chrec_b))
{
case POLYNOMIAL_CHREC:
if (CHREC_VARIABLE (chrec_a) != CHREC_VARIABLE (chrec_b))
return false;
default:
return true;
}
default:
return true;
}
}
return false;
}
/* Analyze a ZIV (Zero Index Variable) subscript. *OVERLAPS_A and
*OVERLAPS_B are initialized to the functions that describe the
relation between the elements accessed twice by CHREC_A and
CHREC_B. For k >= 0, the following property is verified:
CHREC_A (*OVERLAPS_A (k)) = CHREC_B (*OVERLAPS_B (k)). */
static void
analyze_ziv_subscript (tree chrec_a,
tree chrec_b,
tree *overlaps_a,
tree *overlaps_b,
tree *last_conflicts)
{
tree difference;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "(analyze_ziv_subscript \n");
difference = chrec_fold_minus (integer_type_node, chrec_a, chrec_b);
switch (TREE_CODE (difference))
{
case INTEGER_CST:
if (integer_zerop (difference))
{
/* The difference is equal to zero: the accessed index
overlaps for each iteration in the loop. */
*overlaps_a = integer_zero_node;
*overlaps_b = integer_zero_node;
*last_conflicts = chrec_dont_know;
}
else
{
/* The accesses do not overlap. */
*overlaps_a = chrec_known;
*overlaps_b = chrec_known;
*last_conflicts = integer_zero_node;
}
break;
default:
/* We're not sure whether the indexes overlap. For the moment,
conservatively answer "don't know". */
*overlaps_a = chrec_dont_know;
*overlaps_b = chrec_dont_know;
*last_conflicts = chrec_dont_know;
break;
}
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, ")\n");
}
/* Analyze a SIV (Single Index Variable) subscript where CHREC_A is a
constant, and CHREC_B is an affine function. *OVERLAPS_A and
*OVERLAPS_B are initialized to the functions that describe the
relation between the elements accessed twice by CHREC_A and
CHREC_B. For k >= 0, the following property is verified:
CHREC_A (*OVERLAPS_A (k)) = CHREC_B (*OVERLAPS_B (k)). */
static void
analyze_siv_subscript_cst_affine (tree chrec_a,
tree chrec_b,
tree *overlaps_a,
tree *overlaps_b,
tree *last_conflicts)
{
bool value0, value1, value2;
tree difference = chrec_fold_minus
(integer_type_node, CHREC_LEFT (chrec_b), chrec_a);
if (!chrec_is_positive (initial_condition (difference), &value0))
{
*overlaps_a = chrec_dont_know;
*overlaps_b = chrec_dont_know;
*last_conflicts = chrec_dont_know;
return;
}
else
{
if (value0 == false)
{
if (!chrec_is_positive (CHREC_RIGHT (chrec_b), &value1))
{
*overlaps_a = chrec_dont_know;
*overlaps_b = chrec_dont_know;
*last_conflicts = chrec_dont_know;
return;
}
else
{
if (value1 == true)
{
/* Example:
chrec_a = 12
chrec_b = {10, +, 1}
*/
if (tree_fold_divides_p
(integer_type_node, CHREC_RIGHT (chrec_b), difference))
{
*overlaps_a = integer_zero_node;
*overlaps_b = fold
(build (EXACT_DIV_EXPR, integer_type_node,
fold (build1 (ABS_EXPR, integer_type_node, difference)),
CHREC_RIGHT (chrec_b)));
*last_conflicts = integer_one_node;
return;
}
/* When the step does not divides the difference, there are
no overlaps. */
else
{
*overlaps_a = chrec_known;
*overlaps_b = chrec_known;
*last_conflicts = integer_zero_node;
return;
}
}
else
{
/* Example:
chrec_a = 12
chrec_b = {10, +, -1}
In this case, chrec_a will not overlap with chrec_b. */
*overlaps_a = chrec_known;
*overlaps_b = chrec_known;
*last_conflicts = integer_zero_node;
return;
}
}
}
else
{
if (!chrec_is_positive (CHREC_RIGHT (chrec_b), &value2))
{
*overlaps_a = chrec_dont_know;
*overlaps_b = chrec_dont_know;
*last_conflicts = chrec_dont_know;
return;
}
else
{
if (value2 == false)
{
/* Example:
chrec_a = 3
chrec_b = {10, +, -1}
*/
if (tree_fold_divides_p
(integer_type_node, CHREC_RIGHT (chrec_b), difference))
{
*overlaps_a = integer_zero_node;
*overlaps_b = fold
(build (EXACT_DIV_EXPR, integer_type_node, difference,
CHREC_RIGHT (chrec_b)));
*last_conflicts = integer_one_node;
return;
}
/* When the step does not divides the difference, there