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>
6 This file is part of GCC.
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
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
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/>. */
22 #ifndef GCC_TREE_DATA_REF_H
23 #define GCC_TREE_DATA_REF_H
28 #include "tree-chrec.h"
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
37 for (i = 0; i < 100; i++)
38 for (j = 3; j < 100; j++)
41 data-ref a[j].b[i][j] *(p + x + 16B + 4B * j)
44 innermost_loop_behavior
47 init 3 * D_j + offsetof (b) 28
51 struct innermost_loop_behavior
58 /* Alignment information. ALIGNED_TO is set to the largest power of two
59 that divides OFFSET. */
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,
72 base_object: a[0].b[0][0] *(p + x + 4B * j_0)
73 indices: {j_0, +, 1}_2 {16, +, 4}_2
83 /* A list of chrecs. Access functions of the indices. */
84 VEC(tree
,heap
) *access_fns
;
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
;
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. */
99 /* Each vector of the access matrix represents a linear access
100 function for a subscript. First elements correspond to the
101 leftmost indices, ie. for a[i][j] the first vector corresponds to
102 the subscript in "i". The elements of a vector are relative to
103 the loop nests in which the data reference is considered,
104 i.e. the vector is relative to the SCoP that provides the context
105 in which this data reference occurs.
113 if "i" varies in loop_1 and "j" varies in loop_2, the access
114 matrix with respect to the loop nest {loop_1, loop_2} is:
116 | loop_1 loop_2 param_n cst
120 whereas the access matrix with respect to loop_2 considers "i" as
123 | loop_2 param_i param_n cst
129 VEC (loop_p
, heap
) *loop_nest
;
130 int nb_induction_vars
;
131 VEC (tree
, heap
) *parameters
;
132 VEC (lambda_vector
, gc
) *matrix
;
135 #define AM_LOOP_NEST(M) (M)->loop_nest
136 #define AM_NB_INDUCTION_VARS(M) (M)->nb_induction_vars
137 #define AM_PARAMETERS(M) (M)->parameters
138 #define AM_MATRIX(M) (M)->matrix
139 #define AM_NB_PARAMETERS(M) (VEC_length (tree, AM_PARAMETERS(M)))
140 #define AM_CONST_COLUMN_INDEX(M) (AM_NB_INDUCTION_VARS (M) + AM_NB_PARAMETERS (M))
141 #define AM_NB_COLUMNS(M) (AM_NB_INDUCTION_VARS (M) + AM_NB_PARAMETERS (M) + 1)
142 #define AM_GET_SUBSCRIPT_ACCESS_VECTOR(M, I) VEC_index (lambda_vector, AM_MATRIX (M), I)
143 #define AM_GET_ACCESS_MATRIX_ELEMENT(M, I, J) AM_GET_SUBSCRIPT_ACCESS_VECTOR (M, I)[J]
145 /* Return the column in the access matrix of LOOP_NUM. */
148 am_vector_index_for_loop (struct access_matrix
*access_matrix
, int loop_num
)
153 for (i
= 0; VEC_iterate (loop_p
, AM_LOOP_NEST (access_matrix
), i
, l
); i
++)
154 if (l
->num
== loop_num
)
160 int access_matrix_get_index_for_parameter (tree
, struct access_matrix
*);
162 struct data_reference
164 /* A pointer to the statement that contains this DR. */
167 /* A pointer to the memory reference. */
170 /* Auxiliary info specific to a pass. */
173 /* True when the data reference is in RHS of a stmt. */
176 /* Behavior of the memory reference in the innermost loop. */
177 struct innermost_loop_behavior innermost
;
179 /* Subscripts of this data reference. */
180 struct indices indices
;
182 /* Alias information for the data reference. */
183 struct dr_alias alias
;
185 /* Matrix representation for the data access functions. */
186 struct access_matrix
*access_matrix
;
189 #define DR_STMT(DR) (DR)->stmt
190 #define DR_REF(DR) (DR)->ref
191 #define DR_BASE_OBJECT(DR) (DR)->indices.base_object
192 #define DR_ACCESS_FNS(DR) (DR)->indices.access_fns
193 #define DR_ACCESS_FN(DR, I) VEC_index (tree, DR_ACCESS_FNS (DR), I)
194 #define DR_NUM_DIMENSIONS(DR) VEC_length (tree, DR_ACCESS_FNS (DR))
195 #define DR_IS_READ(DR) (DR)->is_read
196 #define DR_BASE_ADDRESS(DR) (DR)->innermost.base_address
197 #define DR_OFFSET(DR) (DR)->innermost.offset
198 #define DR_INIT(DR) (DR)->innermost.init
199 #define DR_STEP(DR) (DR)->innermost.step
200 #define DR_PTR_INFO(DR) (DR)->alias.ptr_info
201 #define DR_ALIGNED_TO(DR) (DR)->innermost.aligned_to
202 #define DR_ACCESS_MATRIX(DR) (DR)->access_matrix
204 typedef struct data_reference
*data_reference_p
;
205 DEF_VEC_P(data_reference_p
);
206 DEF_VEC_ALLOC_P (data_reference_p
, heap
);
208 enum data_dependence_direction
{
212 dir_positive_or_negative
,
213 dir_positive_or_equal
,
214 dir_negative_or_equal
,
219 /* The description of the grid of iterations that overlap. At most
220 two loops are considered at the same time just now, hence at most
221 two functions are needed. For each of the functions, we store
222 the vector of coefficients, f[0] + x * f[1] + y * f[2] + ...,
223 where x, y, ... are variables. */
227 /* Special values of N. */
228 #define NO_DEPENDENCE 0
229 #define NOT_KNOWN (MAX_DIM + 1)
230 #define CF_NONTRIVIAL_P(CF) ((CF)->n != NO_DEPENDENCE && (CF)->n != NOT_KNOWN)
231 #define CF_NOT_KNOWN_P(CF) ((CF)->n == NOT_KNOWN)
232 #define CF_NO_DEPENDENCE_P(CF) ((CF)->n == NO_DEPENDENCE)
234 typedef VEC (tree
, heap
) *affine_fn
;
239 affine_fn fns
[MAX_DIM
];
242 /* What is a subscript? Given two array accesses a subscript is the
243 tuple composed of the access functions for a given dimension.
244 Example: Given A[f1][f2][f3] and B[g1][g2][g3], there are three
245 subscripts: (f1, g1), (f2, g2), (f3, g3). These three subscripts
246 are stored in the data_dependence_relation structure under the form
247 of an array of subscripts. */
251 /* A description of the iterations for which the elements are
253 conflict_function
*conflicting_iterations_in_a
;
254 conflict_function
*conflicting_iterations_in_b
;
256 /* This field stores the information about the iteration domain
257 validity of the dependence relation. */
260 /* Distance from the iteration that access a conflicting element in
261 A to the iteration that access this same conflicting element in
262 B. The distance is a tree scalar expression, i.e. a constant or a
263 symbolic expression, but certainly not a chrec function. */
267 typedef struct subscript
*subscript_p
;
268 DEF_VEC_P(subscript_p
);
269 DEF_VEC_ALLOC_P (subscript_p
, heap
);
271 #define SUB_CONFLICTS_IN_A(SUB) SUB->conflicting_iterations_in_a
272 #define SUB_CONFLICTS_IN_B(SUB) SUB->conflicting_iterations_in_b
273 #define SUB_LAST_CONFLICT(SUB) SUB->last_conflict
274 #define SUB_DISTANCE(SUB) SUB->distance
276 /* A data_dependence_relation represents a relation between two
277 data_references A and B. */
279 struct data_dependence_relation
282 struct data_reference
*a
;
283 struct data_reference
*b
;
285 /* A "yes/no/maybe" field for the dependence relation:
287 - when "ARE_DEPENDENT == NULL_TREE", there exist a dependence
288 relation between A and B, and the description of this relation
289 is given in the SUBSCRIPTS array,
291 - when "ARE_DEPENDENT == chrec_known", there is no dependence and
294 - when "ARE_DEPENDENT == chrec_dont_know", there may be a dependence,
295 but the analyzer cannot be more specific. */
298 /* For each subscript in the dependence test, there is an element in
299 this array. This is the attribute that labels the edge A->B of
300 the data_dependence_relation. */
301 VEC (subscript_p
, heap
) *subscripts
;
303 /* The analyzed loop nest. */
304 VEC (loop_p
, heap
) *loop_nest
;
306 /* The classic direction vector. */
307 VEC (lambda_vector
, heap
) *dir_vects
;
309 /* The classic distance vector. */
310 VEC (lambda_vector
, heap
) *dist_vects
;
312 /* An index in loop_nest for the innermost loop that varies for
313 this data dependence relation. */
316 /* Is the dependence reversed with respect to the lexicographic order? */
319 /* When the dependence relation is affine, it can be represented by
320 a distance vector. */
323 /* Set to true when the dependence relation is on the same data
325 bool self_reference_p
;
328 typedef struct data_dependence_relation
*ddr_p
;
330 DEF_VEC_ALLOC_P(ddr_p
,heap
);
332 #define DDR_A(DDR) DDR->a
333 #define DDR_B(DDR) DDR->b
334 #define DDR_AFFINE_P(DDR) DDR->affine_p
335 #define DDR_ARE_DEPENDENT(DDR) DDR->are_dependent
336 #define DDR_SUBSCRIPTS(DDR) DDR->subscripts
337 #define DDR_SUBSCRIPT(DDR, I) VEC_index (subscript_p, DDR_SUBSCRIPTS (DDR), I)
338 #define DDR_NUM_SUBSCRIPTS(DDR) VEC_length (subscript_p, DDR_SUBSCRIPTS (DDR))
340 #define DDR_LOOP_NEST(DDR) DDR->loop_nest
341 /* The size of the direction/distance vectors: the number of loops in
343 #define DDR_NB_LOOPS(DDR) (VEC_length (loop_p, DDR_LOOP_NEST (DDR)))
344 #define DDR_INNER_LOOP(DDR) DDR->inner_loop
345 #define DDR_SELF_REFERENCE(DDR) DDR->self_reference_p
347 #define DDR_DIST_VECTS(DDR) ((DDR)->dist_vects)
348 #define DDR_DIR_VECTS(DDR) ((DDR)->dir_vects)
349 #define DDR_NUM_DIST_VECTS(DDR) \
350 (VEC_length (lambda_vector, DDR_DIST_VECTS (DDR)))
351 #define DDR_NUM_DIR_VECTS(DDR) \
352 (VEC_length (lambda_vector, DDR_DIR_VECTS (DDR)))
353 #define DDR_DIR_VECT(DDR, I) \
354 VEC_index (lambda_vector, DDR_DIR_VECTS (DDR), I)
355 #define DDR_DIST_VECT(DDR, I) \
356 VEC_index (lambda_vector, DDR_DIST_VECTS (DDR), I)
357 #define DDR_REVERSED_P(DDR) DDR->reversed_p
361 /* Describes a location of a memory reference. */
363 typedef struct data_ref_loc_d
365 /* Position of the memory reference. */
368 /* True if the memory reference is read. */
372 DEF_VEC_O (data_ref_loc
);
373 DEF_VEC_ALLOC_O (data_ref_loc
, heap
);
375 bool get_references_in_stmt (gimple
, VEC (data_ref_loc
, heap
) **);
376 bool dr_analyze_innermost (struct data_reference
*);
377 extern bool compute_data_dependences_for_loop (struct loop
*, bool,
378 VEC (data_reference_p
, heap
) **,
379 VEC (ddr_p
, heap
) **);
380 extern bool compute_data_dependences_for_bb (basic_block
, bool,
381 VEC (data_reference_p
, heap
) **,
382 VEC (ddr_p
, heap
) **);
383 extern tree
find_data_references_in_loop (struct loop
*,
384 VEC (data_reference_p
, heap
) **);
385 extern void print_direction_vector (FILE *, lambda_vector
, int);
386 extern void print_dir_vectors (FILE *, VEC (lambda_vector
, heap
) *, int);
387 extern void print_dist_vectors (FILE *, VEC (lambda_vector
, heap
) *, int);
388 extern void dump_subscript (FILE *, struct subscript
*);
389 extern void dump_ddrs (FILE *, VEC (ddr_p
, heap
) *);
390 extern void dump_dist_dir_vectors (FILE *, VEC (ddr_p
, heap
) *);
391 extern void dump_data_reference (FILE *, struct data_reference
*);
392 extern void debug_data_reference (struct data_reference
*);
393 extern void dump_data_references (FILE *, VEC (data_reference_p
, heap
) *);
394 extern void debug_data_references (VEC (data_reference_p
, heap
) *);
395 extern void debug_data_dependence_relation (struct data_dependence_relation
*);
396 extern void dump_data_dependence_relation (FILE *,
397 struct data_dependence_relation
*);
398 extern void dump_data_dependence_relations (FILE *, VEC (ddr_p
, heap
) *);
399 extern void debug_data_dependence_relations (VEC (ddr_p
, heap
) *);
400 extern void dump_data_dependence_direction (FILE *,
401 enum data_dependence_direction
);
402 extern void free_dependence_relation (struct data_dependence_relation
*);
403 extern void free_dependence_relations (VEC (ddr_p
, heap
) *);
404 extern void free_data_ref (data_reference_p
);
405 extern void free_data_refs (VEC (data_reference_p
, heap
) *);
406 extern bool find_data_references_in_stmt (struct loop
*, gimple
,
407 VEC (data_reference_p
, heap
) **);
408 extern bool graphite_find_data_references_in_stmt (struct loop
*, gimple
,
409 VEC (data_reference_p
, heap
) **);
410 struct data_reference
*create_data_ref (struct loop
*, tree
, gimple
, bool);
411 extern bool find_loop_nest (struct loop
*, VEC (loop_p
, heap
) **);
412 extern void compute_all_dependences (VEC (data_reference_p
, heap
) *,
413 VEC (ddr_p
, heap
) **, VEC (loop_p
, heap
) *,
416 extern void create_rdg_vertices (struct graph
*, VEC (gimple
, heap
) *);
417 extern bool dr_may_alias_p (const struct data_reference
*,
418 const struct data_reference
*);
420 /* Return true when the DDR contains two data references that have the
421 same access functions. */
424 same_access_functions (const struct data_dependence_relation
*ddr
)
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
)))
436 /* Return true when DDR is an anti-dependence relation. */
439 ddr_is_anti_dependent (ddr_p ddr
)
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
));
447 /* Return true when DEPENDENCE_RELATIONS contains an anti-dependence. */
450 ddrs_have_anti_deps (VEC (ddr_p
, heap
) *dependence_relations
)
455 for (i
= 0; VEC_iterate (ddr_p
, dependence_relations
, i
, ddr
); i
++)
456 if (ddr_is_anti_dependent (ddr
))
462 /* Return the dependence level for the DDR relation. */
464 static inline unsigned
465 ddr_dependence_level (ddr_p ddr
)
470 if (DDR_DIST_VECTS (ddr
))
471 level
= dependence_level (DDR_DIST_VECT (ddr
, 0), DDR_NB_LOOPS (ddr
));
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
)));
481 /* A Reduced Dependence Graph (RDG) vertex representing a statement. */
482 typedef struct rdg_vertex
484 /* The statement represented by this vertex. */
487 /* True when the statement contains a write to memory. */
490 /* True when the statement contains a read from memory. */
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]))
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 int rdg_vertex_for_stmt (struct graph
*, gimple
);
509 /* Data dependence type. */
513 /* Read After Write (RAW). */
516 /* Write After Read (WAR). */
519 /* Write After Write (WAW). */
522 /* Read After Read (RAR). */
526 /* Dependence information attached to an edge of the RDG. */
528 typedef struct rdg_edge
530 /* Type of the dependence. */
531 enum rdg_dep_type type
;
533 /* Levels of the dependence: the depth of the loops that carry the
537 /* Dependence relation between data dependences, NULL when one of
538 the vertices is a scalar. */
542 #define RDGE_TYPE(E) ((struct rdg_edge *) ((E)->data))->type
543 #define RDGE_LEVEL(E) ((struct rdg_edge *) ((E)->data))->level
544 #define RDGE_RELATION(E) ((struct rdg_edge *) ((E)->data))->relation
546 struct graph
*build_rdg (struct loop
*);
547 struct graph
*build_empty_rdg (int);
548 void free_rdg (struct graph
*);
550 /* Return the index of the variable VAR in the LOOP_NEST array. */
553 index_in_loop_nest (int var
, VEC (loop_p
, heap
) *loop_nest
)
558 for (var_index
= 0; VEC_iterate (loop_p
, loop_nest
, var_index
, loopi
);
560 if (loopi
->num
== var
)
566 void stores_from_loop (struct loop
*, VEC (gimple
, heap
) **);
567 void remove_similar_memory_refs (VEC (gimple
, heap
) **);
568 bool rdg_defs_used_in_other_loops_p (struct graph
*, int);
569 bool have_similar_memory_accesses (gimple
, gimple
);
571 /* Determines whether RDG vertices V1 and V2 access to similar memory
572 locations, in which case they have to be in the same partition. */
575 rdg_has_similar_memory_accesses (struct graph
*rdg
, int v1
, int v2
)
577 return have_similar_memory_accesses (RDG_STMT (rdg
, v1
),
581 /* In lambda-code.c */
582 bool lambda_transform_legal_p (lambda_trans_matrix
, int,
583 VEC (ddr_p
, heap
) *);
584 void lambda_collect_parameters (VEC (data_reference_p
, heap
) *,
585 VEC (tree
, heap
) **);
586 bool lambda_compute_access_matrices (VEC (data_reference_p
, heap
) *,
588 VEC (loop_p
, heap
) *,
591 /* In tree-data-ref.c */
592 void split_constant_offset (tree
, tree
*, tree
*);
594 /* Strongly connected components of the reduced data dependence graph. */
596 typedef struct rdg_component
599 VEC (int, heap
) *vertices
;
603 DEF_VEC_ALLOC_P (rdgc
, heap
);
606 DEF_VEC_ALLOC_P (bitmap
, heap
);
608 #endif /* GCC_TREE_DATA_REF_H */