re PR preprocessor/36674 (#include location is offset by one row in errors from prepr...
[gcc.git] / gcc / tree-data-ref.h
1 /* Data references and dependences detectors.
2 Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009
3 Free Software Foundation, Inc.
4 Contributed by Sebastian Pop <pop@cri.ensmp.fr>
5
6 This file is part of GCC.
7
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
11 version.
12
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
21
22 #ifndef GCC_TREE_DATA_REF_H
23 #define GCC_TREE_DATA_REF_H
24
25 #include "graphds.h"
26 #include "lambda.h"
27 #include "omega.h"
28 #include "tree-chrec.h"
29
30 /*
31 innermost_loop_behavior describes the evolution of the address of the memory
32 reference in the innermost enclosing loop. The address is expressed as
33 BASE + STEP * # of iteration, and base is further decomposed as the base
34 pointer (BASE_ADDRESS), loop invariant offset (OFFSET) and
35 constant offset (INIT). Examples, in loop nest
36
37 for (i = 0; i < 100; i++)
38 for (j = 3; j < 100; j++)
39
40 Example 1 Example 2
41 data-ref a[j].b[i][j] *(p + x + 16B + 4B * j)
42
43
44 innermost_loop_behavior
45 base_address &a p
46 offset i * D_i x
47 init 3 * D_j + offsetof (b) 28
48 step D_j 4
49
50 */
51 struct innermost_loop_behavior
52 {
53 tree base_address;
54 tree offset;
55 tree init;
56 tree step;
57
58 /* Alignment information. ALIGNED_TO is set to the largest power of two
59 that divides OFFSET. */
60 tree aligned_to;
61 };
62
63 /* Describes the evolutions of indices of the memory reference. The indices
64 are indices of the ARRAY_REFs and the operands of INDIRECT_REFs.
65 For ARRAY_REFs, BASE_OBJECT is the reference with zeroed indices
66 (note that this reference does not have to be valid, if zero does not
67 belong to the range of the array; hence it is not recommended to use
68 BASE_OBJECT in any code generation). For INDIRECT_REFs, the address is
69 set to the loop-invariant part of the address of the object, except for
70 the constant offset. For the examples above,
71
72 base_object: a[0].b[0][0] *(p + x + 4B * j_0)
73 indices: {j_0, +, 1}_2 {16, +, 4}_2
74 {i_0, +, 1}_1
75 {j_0, +, 1}_2
76 */
77
78 struct indices
79 {
80 /* The object. */
81 tree base_object;
82
83 /* A list of chrecs. Access functions of the indices. */
84 VEC(tree,heap) *access_fns;
85 };
86
87 struct dr_alias
88 {
89 /* The alias information that should be used for new pointers to this
90 location. SYMBOL_TAG is either a DECL or a SYMBOL_MEMORY_TAG. */
91 struct ptr_info_def *ptr_info;
92
93 /* The set of virtual operands corresponding to this memory reference,
94 serving as a description of the alias information for the memory
95 reference. This could be eliminated if we had alias oracle. */
96 bitmap vops;
97 };
98
99 typedef struct scop *scop_p;
100
101 /* Each vector of the access matrix represents a linear access
102 function for a subscript. First elements correspond to the
103 leftmost indices, ie. for a[i][j] the first vector corresponds to
104 the subscript in "i". The elements of a vector are relative to
105 the loop nests in which the data reference is considered,
106 i.e. the vector is relative to the SCoP that provides the context
107 in which this data reference occurs.
108
109 For example, in
110
111 | loop_1
112 | loop_2
113 | a[i+3][2*j+n-1]
114
115 if "i" varies in loop_1 and "j" varies in loop_2, the access
116 matrix with respect to the loop nest {loop_1, loop_2} is:
117
118 | loop_1 loop_2 param_n cst
119 | 1 0 0 3
120 | 0 2 1 -1
121
122 whereas the access matrix with respect to loop_2 considers "i" as
123 a parameter:
124
125 | loop_2 param_i param_n cst
126 | 0 1 0 3
127 | 2 0 1 -1
128 */
129 struct access_matrix
130 {
131 VEC (loop_p, heap) *loop_nest;
132 int nb_induction_vars;
133 VEC (tree, heap) *parameters;
134 VEC (lambda_vector, gc) *matrix;
135 };
136
137 #define AM_LOOP_NEST(M) (M)->loop_nest
138 #define AM_NB_INDUCTION_VARS(M) (M)->nb_induction_vars
139 #define AM_PARAMETERS(M) (M)->parameters
140 #define AM_MATRIX(M) (M)->matrix
141 #define AM_NB_PARAMETERS(M) (VEC_length (tree, AM_PARAMETERS(M)))
142 #define AM_CONST_COLUMN_INDEX(M) (AM_NB_INDUCTION_VARS (M) + AM_NB_PARAMETERS (M))
143 #define AM_NB_COLUMNS(M) (AM_NB_INDUCTION_VARS (M) + AM_NB_PARAMETERS (M) + 1)
144 #define AM_GET_SUBSCRIPT_ACCESS_VECTOR(M, I) VEC_index (lambda_vector, AM_MATRIX (M), I)
145 #define AM_GET_ACCESS_MATRIX_ELEMENT(M, I, J) AM_GET_SUBSCRIPT_ACCESS_VECTOR (M, I)[J]
146
147 /* Return the column in the access matrix of LOOP_NUM. */
148
149 static inline int
150 am_vector_index_for_loop (struct access_matrix *access_matrix, int loop_num)
151 {
152 int i;
153 loop_p l;
154
155 for (i = 0; VEC_iterate (loop_p, AM_LOOP_NEST (access_matrix), i, l); i++)
156 if (l->num == loop_num)
157 return i;
158
159 gcc_unreachable();
160 }
161
162 int access_matrix_get_index_for_parameter (tree, struct access_matrix *);
163
164 struct data_reference
165 {
166 /* A pointer to the statement that contains this DR. */
167 gimple stmt;
168
169 /* A pointer to the memory reference. */
170 tree ref;
171
172 /* Auxiliary info specific to a pass. */
173 void *aux;
174
175 /* True when the data reference is in RHS of a stmt. */
176 bool is_read;
177
178 /* Behavior of the memory reference in the innermost loop. */
179 struct innermost_loop_behavior innermost;
180
181 /* Subscripts of this data reference. */
182 struct indices indices;
183
184 /* Alias information for the data reference. */
185 struct dr_alias alias;
186
187 /* The SCoP in which the data reference was analyzed. */
188 scop_p scop;
189
190 /* Matrix representation for the data access functions. */
191 struct access_matrix *access_matrix;
192 };
193
194 #define DR_SCOP(DR) (DR)->scop
195 #define DR_STMT(DR) (DR)->stmt
196 #define DR_REF(DR) (DR)->ref
197 #define DR_BASE_OBJECT(DR) (DR)->indices.base_object
198 #define DR_ACCESS_FNS(DR) (DR)->indices.access_fns
199 #define DR_ACCESS_FN(DR, I) VEC_index (tree, DR_ACCESS_FNS (DR), I)
200 #define DR_NUM_DIMENSIONS(DR) VEC_length (tree, DR_ACCESS_FNS (DR))
201 #define DR_IS_READ(DR) (DR)->is_read
202 #define DR_BASE_ADDRESS(DR) (DR)->innermost.base_address
203 #define DR_OFFSET(DR) (DR)->innermost.offset
204 #define DR_INIT(DR) (DR)->innermost.init
205 #define DR_STEP(DR) (DR)->innermost.step
206 #define DR_PTR_INFO(DR) (DR)->alias.ptr_info
207 #define DR_ALIGNED_TO(DR) (DR)->innermost.aligned_to
208 #define DR_ACCESS_MATRIX(DR) (DR)->access_matrix
209
210 typedef struct data_reference *data_reference_p;
211 DEF_VEC_P(data_reference_p);
212 DEF_VEC_ALLOC_P (data_reference_p, heap);
213
214 enum data_dependence_direction {
215 dir_positive,
216 dir_negative,
217 dir_equal,
218 dir_positive_or_negative,
219 dir_positive_or_equal,
220 dir_negative_or_equal,
221 dir_star,
222 dir_independent
223 };
224
225 /* The description of the grid of iterations that overlap. At most
226 two loops are considered at the same time just now, hence at most
227 two functions are needed. For each of the functions, we store
228 the vector of coefficients, f[0] + x * f[1] + y * f[2] + ...,
229 where x, y, ... are variables. */
230
231 #define MAX_DIM 2
232
233 /* Special values of N. */
234 #define NO_DEPENDENCE 0
235 #define NOT_KNOWN (MAX_DIM + 1)
236 #define CF_NONTRIVIAL_P(CF) ((CF)->n != NO_DEPENDENCE && (CF)->n != NOT_KNOWN)
237 #define CF_NOT_KNOWN_P(CF) ((CF)->n == NOT_KNOWN)
238 #define CF_NO_DEPENDENCE_P(CF) ((CF)->n == NO_DEPENDENCE)
239
240 typedef VEC (tree, heap) *affine_fn;
241
242 typedef struct
243 {
244 unsigned n;
245 affine_fn fns[MAX_DIM];
246 } conflict_function;
247
248 /* What is a subscript? Given two array accesses a subscript is the
249 tuple composed of the access functions for a given dimension.
250 Example: Given A[f1][f2][f3] and B[g1][g2][g3], there are three
251 subscripts: (f1, g1), (f2, g2), (f3, g3). These three subscripts
252 are stored in the data_dependence_relation structure under the form
253 of an array of subscripts. */
254
255 struct subscript
256 {
257 /* A description of the iterations for which the elements are
258 accessed twice. */
259 conflict_function *conflicting_iterations_in_a;
260 conflict_function *conflicting_iterations_in_b;
261
262 /* This field stores the information about the iteration domain
263 validity of the dependence relation. */
264 tree last_conflict;
265
266 /* Distance from the iteration that access a conflicting element in
267 A to the iteration that access this same conflicting element in
268 B. The distance is a tree scalar expression, i.e. a constant or a
269 symbolic expression, but certainly not a chrec function. */
270 tree distance;
271 };
272
273 typedef struct subscript *subscript_p;
274 DEF_VEC_P(subscript_p);
275 DEF_VEC_ALLOC_P (subscript_p, heap);
276
277 #define SUB_CONFLICTS_IN_A(SUB) SUB->conflicting_iterations_in_a
278 #define SUB_CONFLICTS_IN_B(SUB) SUB->conflicting_iterations_in_b
279 #define SUB_LAST_CONFLICT(SUB) SUB->last_conflict
280 #define SUB_DISTANCE(SUB) SUB->distance
281
282 /* A data_dependence_relation represents a relation between two
283 data_references A and B. */
284
285 struct data_dependence_relation
286 {
287
288 struct data_reference *a;
289 struct data_reference *b;
290
291 /* A "yes/no/maybe" field for the dependence relation:
292
293 - when "ARE_DEPENDENT == NULL_TREE", there exist a dependence
294 relation between A and B, and the description of this relation
295 is given in the SUBSCRIPTS array,
296
297 - when "ARE_DEPENDENT == chrec_known", there is no dependence and
298 SUBSCRIPTS is empty,
299
300 - when "ARE_DEPENDENT == chrec_dont_know", there may be a dependence,
301 but the analyzer cannot be more specific. */
302 tree are_dependent;
303
304 /* For each subscript in the dependence test, there is an element in
305 this array. This is the attribute that labels the edge A->B of
306 the data_dependence_relation. */
307 VEC (subscript_p, heap) *subscripts;
308
309 /* The analyzed loop nest. */
310 VEC (loop_p, heap) *loop_nest;
311
312 /* The classic direction vector. */
313 VEC (lambda_vector, heap) *dir_vects;
314
315 /* The classic distance vector. */
316 VEC (lambda_vector, heap) *dist_vects;
317
318 /* An index in loop_nest for the innermost loop that varies for
319 this data dependence relation. */
320 unsigned inner_loop;
321
322 /* Is the dependence reversed with respect to the lexicographic order? */
323 bool reversed_p;
324
325 /* When the dependence relation is affine, it can be represented by
326 a distance vector. */
327 bool affine_p;
328
329 /* Set to true when the dependence relation is on the same data
330 access. */
331 bool self_reference_p;
332 };
333
334 typedef struct data_dependence_relation *ddr_p;
335 DEF_VEC_P(ddr_p);
336 DEF_VEC_ALLOC_P(ddr_p,heap);
337
338 #define DDR_A(DDR) DDR->a
339 #define DDR_B(DDR) DDR->b
340 #define DDR_AFFINE_P(DDR) DDR->affine_p
341 #define DDR_ARE_DEPENDENT(DDR) DDR->are_dependent
342 #define DDR_SUBSCRIPTS(DDR) DDR->subscripts
343 #define DDR_SUBSCRIPT(DDR, I) VEC_index (subscript_p, DDR_SUBSCRIPTS (DDR), I)
344 #define DDR_NUM_SUBSCRIPTS(DDR) VEC_length (subscript_p, DDR_SUBSCRIPTS (DDR))
345
346 #define DDR_LOOP_NEST(DDR) DDR->loop_nest
347 /* The size of the direction/distance vectors: the number of loops in
348 the loop nest. */
349 #define DDR_NB_LOOPS(DDR) (VEC_length (loop_p, DDR_LOOP_NEST (DDR)))
350 #define DDR_INNER_LOOP(DDR) DDR->inner_loop
351 #define DDR_SELF_REFERENCE(DDR) DDR->self_reference_p
352
353 #define DDR_DIST_VECTS(DDR) ((DDR)->dist_vects)
354 #define DDR_DIR_VECTS(DDR) ((DDR)->dir_vects)
355 #define DDR_NUM_DIST_VECTS(DDR) \
356 (VEC_length (lambda_vector, DDR_DIST_VECTS (DDR)))
357 #define DDR_NUM_DIR_VECTS(DDR) \
358 (VEC_length (lambda_vector, DDR_DIR_VECTS (DDR)))
359 #define DDR_DIR_VECT(DDR, I) \
360 VEC_index (lambda_vector, DDR_DIR_VECTS (DDR), I)
361 #define DDR_DIST_VECT(DDR, I) \
362 VEC_index (lambda_vector, DDR_DIST_VECTS (DDR), I)
363 #define DDR_REVERSED_P(DDR) DDR->reversed_p
364
365 \f
366
367 /* Describes a location of a memory reference. */
368
369 typedef struct data_ref_loc_d
370 {
371 /* Position of the memory reference. */
372 tree *pos;
373
374 /* True if the memory reference is read. */
375 bool is_read;
376 } data_ref_loc;
377
378 DEF_VEC_O (data_ref_loc);
379 DEF_VEC_ALLOC_O (data_ref_loc, heap);
380
381 bool get_references_in_stmt (gimple, VEC (data_ref_loc, heap) **);
382 bool dr_analyze_innermost (struct data_reference *);
383 extern bool compute_data_dependences_for_loop (struct loop *, bool,
384 VEC (data_reference_p, heap) **,
385 VEC (ddr_p, heap) **);
386 extern tree find_data_references_in_loop (struct loop *,
387 VEC (data_reference_p, heap) **);
388 extern void print_direction_vector (FILE *, lambda_vector, int);
389 extern void print_dir_vectors (FILE *, VEC (lambda_vector, heap) *, int);
390 extern void print_dist_vectors (FILE *, VEC (lambda_vector, heap) *, int);
391 extern void dump_subscript (FILE *, struct subscript *);
392 extern void dump_ddrs (FILE *, VEC (ddr_p, heap) *);
393 extern void dump_dist_dir_vectors (FILE *, VEC (ddr_p, heap) *);
394 extern void dump_data_reference (FILE *, struct data_reference *);
395 extern void dump_data_references (FILE *, VEC (data_reference_p, heap) *);
396 extern void debug_data_dependence_relation (struct data_dependence_relation *);
397 extern void dump_data_dependence_relation (FILE *,
398 struct data_dependence_relation *);
399 extern void dump_data_dependence_relations (FILE *, VEC (ddr_p, heap) *);
400 extern void debug_data_dependence_relations (VEC (ddr_p, heap) *);
401 extern void dump_data_dependence_direction (FILE *,
402 enum data_dependence_direction);
403 extern void free_dependence_relation (struct data_dependence_relation *);
404 extern void free_dependence_relations (VEC (ddr_p, heap) *);
405 extern void free_data_ref (data_reference_p);
406 extern void free_data_refs (VEC (data_reference_p, heap) *);
407 extern bool find_data_references_in_stmt (struct loop *, gimple,
408 VEC (data_reference_p, heap) **);
409 struct data_reference *create_data_ref (struct loop *, tree, gimple, bool);
410 extern bool find_loop_nest (struct loop *, VEC (loop_p, heap) **);
411 extern void compute_all_dependences (VEC (data_reference_p, heap) *,
412 VEC (ddr_p, heap) **, VEC (loop_p, heap) *,
413 bool);
414
415 extern void create_rdg_vertices (struct graph *, VEC (gimple, heap) *);
416 extern bool dr_may_alias_p (const struct data_reference *,
417 const struct data_reference *);
418 extern bool stmt_simple_memref_p (struct loop *, gimple, tree);
419
420 /* Return true when the DDR contains two data references that have the
421 same access functions. */
422
423 static inline bool
424 same_access_functions (const struct data_dependence_relation *ddr)
425 {
426 unsigned i;
427
428 for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++)
429 if (!eq_evolutions_p (DR_ACCESS_FN (DDR_A (ddr), i),
430 DR_ACCESS_FN (DDR_B (ddr), i)))
431 return false;
432
433 return true;
434 }
435
436 /* Return true when DDR is an anti-dependence relation. */
437
438 static inline bool
439 ddr_is_anti_dependent (ddr_p ddr)
440 {
441 return (DDR_ARE_DEPENDENT (ddr) == NULL_TREE
442 && DR_IS_READ (DDR_A (ddr))
443 && !DR_IS_READ (DDR_B (ddr))
444 && !same_access_functions (ddr));
445 }
446
447 /* Return true when DEPENDENCE_RELATIONS contains an anti-dependence. */
448
449 static inline bool
450 ddrs_have_anti_deps (VEC (ddr_p, heap) *dependence_relations)
451 {
452 unsigned i;
453 ddr_p ddr;
454
455 for (i = 0; VEC_iterate (ddr_p, dependence_relations, i, ddr); i++)
456 if (ddr_is_anti_dependent (ddr))
457 return true;
458
459 return false;
460 }
461
462 /* Return the dependence level for the DDR relation. */
463
464 static inline unsigned
465 ddr_dependence_level (ddr_p ddr)
466 {
467 unsigned vector;
468 unsigned level = 0;
469
470 if (DDR_DIST_VECTS (ddr))
471 level = dependence_level (DDR_DIST_VECT (ddr, 0), DDR_NB_LOOPS (ddr));
472
473 for (vector = 1; vector < DDR_NUM_DIST_VECTS (ddr); vector++)
474 level = MIN (level, dependence_level (DDR_DIST_VECT (ddr, vector),
475 DDR_NB_LOOPS (ddr)));
476 return level;
477 }
478
479 \f
480
481 /* A Reduced Dependence Graph (RDG) vertex representing a statement. */
482 typedef struct rdg_vertex
483 {
484 /* The statement represented by this vertex. */
485 gimple stmt;
486
487 /* True when the statement contains a write to memory. */
488 bool has_mem_write;
489
490 /* True when the statement contains a read from memory. */
491 bool has_mem_reads;
492 } *rdg_vertex_p;
493
494 #define RDGV_STMT(V) ((struct rdg_vertex *) ((V)->data))->stmt
495 #define RDGV_HAS_MEM_WRITE(V) ((struct rdg_vertex *) ((V)->data))->has_mem_write
496 #define RDGV_HAS_MEM_READS(V) ((struct rdg_vertex *) ((V)->data))->has_mem_reads
497 #define RDG_STMT(RDG, I) RDGV_STMT (&(RDG->vertices[I]))
498 #define RDG_MEM_WRITE_STMT(RDG, I) RDGV_HAS_MEM_WRITE (&(RDG->vertices[I]))
499 #define RDG_MEM_READS_STMT(RDG, I) RDGV_HAS_MEM_READS (&(RDG->vertices[I]))
500
501 void dump_rdg_vertex (FILE *, struct graph *, int);
502 void debug_rdg_vertex (struct graph *, int);
503 void dump_rdg_component (FILE *, struct graph *, int, bitmap);
504 void debug_rdg_component (struct graph *, int);
505 void dump_rdg (FILE *, struct graph *);
506 void debug_rdg (struct graph *);
507 void dot_rdg (struct graph *);
508 int rdg_vertex_for_stmt (struct graph *, gimple);
509
510 /* Data dependence type. */
511
512 enum rdg_dep_type
513 {
514 /* Read After Write (RAW). */
515 flow_dd = 'f',
516
517 /* Write After Read (WAR). */
518 anti_dd = 'a',
519
520 /* Write After Write (WAW). */
521 output_dd = 'o',
522
523 /* Read After Read (RAR). */
524 input_dd = 'i'
525 };
526
527 /* Dependence information attached to an edge of the RDG. */
528
529 typedef struct rdg_edge
530 {
531 /* Type of the dependence. */
532 enum rdg_dep_type type;
533
534 /* Levels of the dependence: the depth of the loops that carry the
535 dependence. */
536 unsigned level;
537
538 /* Dependence relation between data dependences, NULL when one of
539 the vertices is a scalar. */
540 ddr_p relation;
541 } *rdg_edge_p;
542
543 #define RDGE_TYPE(E) ((struct rdg_edge *) ((E)->data))->type
544 #define RDGE_LEVEL(E) ((struct rdg_edge *) ((E)->data))->level
545 #define RDGE_RELATION(E) ((struct rdg_edge *) ((E)->data))->relation
546
547 struct graph *build_rdg (struct loop *);
548 struct graph *build_empty_rdg (int);
549 void free_rdg (struct graph *);
550
551 /* Return the index of the variable VAR in the LOOP_NEST array. */
552
553 static inline int
554 index_in_loop_nest (int var, VEC (loop_p, heap) *loop_nest)
555 {
556 struct loop *loopi;
557 int var_index;
558
559 for (var_index = 0; VEC_iterate (loop_p, loop_nest, var_index, loopi);
560 var_index++)
561 if (loopi->num == var)
562 break;
563
564 return var_index;
565 }
566
567 void stores_from_loop (struct loop *, VEC (gimple, heap) **);
568 void remove_similar_memory_refs (VEC (gimple, heap) **);
569 bool rdg_defs_used_in_other_loops_p (struct graph *, int);
570 bool have_similar_memory_accesses (gimple, gimple);
571
572 /* Determines whether RDG vertices V1 and V2 access to similar memory
573 locations, in which case they have to be in the same partition. */
574
575 static inline bool
576 rdg_has_similar_memory_accesses (struct graph *rdg, int v1, int v2)
577 {
578 return have_similar_memory_accesses (RDG_STMT (rdg, v1),
579 RDG_STMT (rdg, v2));
580 }
581
582 /* In lambda-code.c */
583 bool lambda_transform_legal_p (lambda_trans_matrix, int,
584 VEC (ddr_p, heap) *);
585 void lambda_collect_parameters (VEC (data_reference_p, heap) *,
586 VEC (tree, heap) **);
587 bool lambda_compute_access_matrices (VEC (data_reference_p, heap) *,
588 VEC (tree, heap) *, VEC (loop_p, heap) *);
589
590 /* In tree-data-ref.c */
591 void split_constant_offset (tree , tree *, tree *);
592
593 /* Strongly connected components of the reduced data dependence graph. */
594
595 typedef struct rdg_component
596 {
597 int num;
598 VEC (int, heap) *vertices;
599 } *rdgc;
600
601 DEF_VEC_P (rdgc);
602 DEF_VEC_ALLOC_P (rdgc, heap);
603
604 DEF_VEC_P (bitmap);
605 DEF_VEC_ALLOC_P (bitmap, heap);
606
607 #endif /* GCC_TREE_DATA_REF_H */