1 /* Data references and dependences detectors.
2 Copyright (C) 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
3 Contributed by Sebastian Pop <pop@cri.ensmp.fr>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
22 /* This pass walks a given loop structure searching for array
23 references. The information about the array accesses is recorded
24 in DATA_REFERENCE structures.
26 The basic test for determining the dependences is:
27 given two access functions chrec1 and chrec2 to a same array, and
28 x and y two vectors from the iteration domain, the same element of
29 the array is accessed twice at iterations x and y if and only if:
30 | chrec1 (x) == chrec2 (y).
32 The goals of this analysis are:
34 - to determine the independence: the relation between two
35 independent accesses is qualified with the chrec_known (this
36 information allows a loop parallelization),
38 - when two data references access the same data, to qualify the
39 dependence relation with classic dependence representations:
43 - loop carried level dependence
44 - polyhedron dependence
45 or with the chains of recurrences based representation,
47 - to define a knowledge base for storing the data dependence
50 - to define an interface to access this data.
55 - subscript: given two array accesses a subscript is the tuple
56 composed of the access functions for a given dimension. Example:
57 Given A[f1][f2][f3] and B[g1][g2][g3], there are three subscripts:
58 (f1, g1), (f2, g2), (f3, g3).
60 - Diophantine equation: an equation whose coefficients and
61 solutions are integer constants, for example the equation
63 has an integer solution x = 1 and y = -1.
67 - "Advanced Compilation for High Performance Computing" by Randy
68 Allen and Ken Kennedy.
69 http://citeseer.ist.psu.edu/goff91practical.html
71 - "Loop Transformations for Restructuring Compilers - The Foundations"
79 #include "coretypes.h"
84 /* These RTL headers are needed for basic-block.h. */
86 #include "basic-block.h"
87 #include "diagnostic.h"
88 #include "tree-flow.h"
89 #include "tree-dump.h"
92 #include "tree-chrec.h"
93 #include "tree-data-ref.h"
94 #include "tree-scalar-evolution.h"
95 #include "tree-pass.h"
96 #include "langhooks.h"
98 static struct datadep_stats
100 int num_dependence_tests;
101 int num_dependence_dependent;
102 int num_dependence_independent;
103 int num_dependence_undetermined;
105 int num_subscript_tests;
106 int num_subscript_undetermined;
107 int num_same_subscript_function;
110 int num_ziv_independent;
111 int num_ziv_dependent;
112 int num_ziv_unimplemented;
115 int num_siv_independent;
116 int num_siv_dependent;
117 int num_siv_unimplemented;
120 int num_miv_independent;
121 int num_miv_dependent;
122 int num_miv_unimplemented;
125 static bool subscript_dependence_tester_1 (struct data_dependence_relation *,
126 struct data_reference *,
127 struct data_reference *,
129 /* Returns true iff A divides B. */
132 tree_fold_divides_p (tree a, tree b)
134 gcc_assert (TREE_CODE (a) == INTEGER_CST);
135 gcc_assert (TREE_CODE (b) == INTEGER_CST);
136 return integer_zerop (int_const_binop (TRUNC_MOD_EXPR, b, a, 0));
139 /* Returns true iff A divides B. */
142 int_divides_p (int a, int b)
144 return ((b % a) == 0);
149 /* Dump into FILE all the data references from DATAREFS. */
152 dump_data_references (FILE *file, VEC (data_reference_p, heap) *datarefs)
155 struct data_reference *dr;
157 for (i = 0; VEC_iterate (data_reference_p, datarefs, i, dr); i++)
158 dump_data_reference (file, dr);
161 /* Dump into FILE all the dependence relations from DDRS. */
164 dump_data_dependence_relations (FILE *file,
165 VEC (ddr_p, heap) *ddrs)
168 struct data_dependence_relation *ddr;
170 for (i = 0; VEC_iterate (ddr_p, ddrs, i, ddr); i++)
171 dump_data_dependence_relation (file, ddr);
174 /* Dump function for a DATA_REFERENCE structure. */
177 dump_data_reference (FILE *outf,
178 struct data_reference *dr)
182 fprintf (outf, "(Data Ref: \n stmt: ");
183 print_generic_stmt (outf, DR_STMT (dr), 0);
184 fprintf (outf, " ref: ");
185 print_generic_stmt (outf, DR_REF (dr), 0);
186 fprintf (outf, " base_object: ");
187 print_generic_stmt (outf, DR_BASE_OBJECT (dr), 0);
189 for (i = 0; i < DR_NUM_DIMENSIONS (dr); i++)
191 fprintf (outf, " Access function %d: ", i);
192 print_generic_stmt (outf, DR_ACCESS_FN (dr, i), 0);
194 fprintf (outf, ")\n");
197 /* Dumps the affine function described by FN to the file OUTF. */
200 dump_affine_function (FILE *outf, affine_fn fn)
205 print_generic_expr (outf, VEC_index (tree, fn, 0), TDF_SLIM);
206 for (i = 1; VEC_iterate (tree, fn, i, coef); i++)
208 fprintf (outf, " + ");
209 print_generic_expr (outf, coef, TDF_SLIM);
210 fprintf (outf, " * x_%u", i);
214 /* Dumps the conflict function CF to the file OUTF. */
217 dump_conflict_function (FILE *outf, conflict_function *cf)
221 if (cf->n == NO_DEPENDENCE)
222 fprintf (outf, "no dependence\n");
223 else if (cf->n == NOT_KNOWN)
224 fprintf (outf, "not known\n");
227 for (i = 0; i < cf->n; i++)
230 dump_affine_function (outf, cf->fns[i]);
231 fprintf (outf, "]\n");
236 /* Dump function for a SUBSCRIPT structure. */
239 dump_subscript (FILE *outf, struct subscript *subscript)
241 conflict_function *cf = SUB_CONFLICTS_IN_A (subscript);
243 fprintf (outf, "\n (subscript \n");
244 fprintf (outf, " iterations_that_access_an_element_twice_in_A: ");
245 dump_conflict_function (outf, cf);
246 if (CF_NONTRIVIAL_P (cf))
248 tree last_iteration = SUB_LAST_CONFLICT (subscript);
249 fprintf (outf, " last_conflict: ");
250 print_generic_stmt (outf, last_iteration, 0);
253 cf = SUB_CONFLICTS_IN_B (subscript);
254 fprintf (outf, " iterations_that_access_an_element_twice_in_B: ");
255 dump_conflict_function (outf, cf);
256 if (CF_NONTRIVIAL_P (cf))
258 tree last_iteration = SUB_LAST_CONFLICT (subscript);
259 fprintf (outf, " last_conflict: ");
260 print_generic_stmt (outf, last_iteration, 0);
263 fprintf (outf, " (Subscript distance: ");
264 print_generic_stmt (outf, SUB_DISTANCE (subscript), 0);
265 fprintf (outf, " )\n");
266 fprintf (outf, " )\n");
269 /* Print the classic direction vector DIRV to OUTF. */
272 print_direction_vector (FILE *outf,
278 for (eq = 0; eq < length; eq++)
280 enum data_dependence_direction dir = dirv[eq];
285 fprintf (outf, " +");
288 fprintf (outf, " -");
291 fprintf (outf, " =");
293 case dir_positive_or_equal:
294 fprintf (outf, " +=");
296 case dir_positive_or_negative:
297 fprintf (outf, " +-");
299 case dir_negative_or_equal:
300 fprintf (outf, " -=");
303 fprintf (outf, " *");
306 fprintf (outf, "indep");
310 fprintf (outf, "\n");
313 /* Print a vector of direction vectors. */
316 print_dir_vectors (FILE *outf, VEC (lambda_vector, heap) *dir_vects,
322 for (j = 0; VEC_iterate (lambda_vector, dir_vects, j, v); j++)
323 print_direction_vector (outf, v, length);
326 /* Print a vector of distance vectors. */
329 print_dist_vectors (FILE *outf, VEC (lambda_vector, heap) *dist_vects,
335 for (j = 0; VEC_iterate (lambda_vector, dist_vects, j, v); j++)
336 print_lambda_vector (outf, v, length);
342 debug_data_dependence_relation (struct data_dependence_relation *ddr)
344 dump_data_dependence_relation (stderr, ddr);
347 /* Dump function for a DATA_DEPENDENCE_RELATION structure. */
350 dump_data_dependence_relation (FILE *outf,
351 struct data_dependence_relation *ddr)
353 struct data_reference *dra, *drb;
357 fprintf (outf, "(Data Dep: \n");
358 if (DDR_ARE_DEPENDENT (ddr) == chrec_dont_know)
359 fprintf (outf, " (don't know)\n");
361 else if (DDR_ARE_DEPENDENT (ddr) == chrec_known)
362 fprintf (outf, " (no dependence)\n");
364 else if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE)
369 for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++)
371 fprintf (outf, " access_fn_A: ");
372 print_generic_stmt (outf, DR_ACCESS_FN (dra, i), 0);
373 fprintf (outf, " access_fn_B: ");
374 print_generic_stmt (outf, DR_ACCESS_FN (drb, i), 0);
375 dump_subscript (outf, DDR_SUBSCRIPT (ddr, i));
378 fprintf (outf, " inner loop index: %d\n", DDR_INNER_LOOP (ddr));
379 fprintf (outf, " loop nest: (");
380 for (i = 0; VEC_iterate (loop_p, DDR_LOOP_NEST (ddr), i, loopi); i++)
381 fprintf (outf, "%d ", loopi->num);
382 fprintf (outf, ")\n");
384 for (i = 0; i < DDR_NUM_DIST_VECTS (ddr); i++)
386 fprintf (outf, " distance_vector: ");
387 print_lambda_vector (outf, DDR_DIST_VECT (ddr, i),
391 for (i = 0; i < DDR_NUM_DIR_VECTS (ddr); i++)
393 fprintf (outf, " direction_vector: ");
394 print_direction_vector (outf, DDR_DIR_VECT (ddr, i),
399 fprintf (outf, ")\n");
402 /* Dump function for a DATA_DEPENDENCE_DIRECTION structure. */
405 dump_data_dependence_direction (FILE *file,
406 enum data_dependence_direction dir)
422 case dir_positive_or_negative:
423 fprintf (file, "+-");
426 case dir_positive_or_equal:
427 fprintf (file, "+=");
430 case dir_negative_or_equal:
431 fprintf (file, "-=");
443 /* Dumps the distance and direction vectors in FILE. DDRS contains
444 the dependence relations, and VECT_SIZE is the size of the
445 dependence vectors, or in other words the number of loops in the
449 dump_dist_dir_vectors (FILE *file, VEC (ddr_p, heap) *ddrs)
452 struct data_dependence_relation *ddr;
455 for (i = 0; VEC_iterate (ddr_p, ddrs, i, ddr); i++)
456 if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE && DDR_AFFINE_P (ddr))
458 for (j = 0; VEC_iterate (lambda_vector, DDR_DIST_VECTS (ddr), j, v); j++)
460 fprintf (file, "DISTANCE_V (");
461 print_lambda_vector (file, v, DDR_NB_LOOPS (ddr));
462 fprintf (file, ")\n");
465 for (j = 0; VEC_iterate (lambda_vector, DDR_DIR_VECTS (ddr), j, v); j++)
467 fprintf (file, "DIRECTION_V (");
468 print_direction_vector (file, v, DDR_NB_LOOPS (ddr));
469 fprintf (file, ")\n");
473 fprintf (file, "\n\n");
476 /* Dumps the data dependence relations DDRS in FILE. */
479 dump_ddrs (FILE *file, VEC (ddr_p, heap) *ddrs)
482 struct data_dependence_relation *ddr;
484 for (i = 0; VEC_iterate (ddr_p, ddrs, i, ddr); i++)
485 dump_data_dependence_relation (file, ddr);
487 fprintf (file, "\n\n");
490 /* Expresses EXP as VAR + OFF, where off is a constant. The type of OFF
491 will be ssizetype. */
494 split_constant_offset (tree exp, tree *var, tree *off)
496 tree type = TREE_TYPE (exp), otype;
503 otype = TREE_TYPE (exp);
504 code = TREE_CODE (exp);
509 *var = build_int_cst (type, 0);
510 *off = fold_convert (ssizetype, exp);
513 case POINTER_PLUS_EXPR:
518 split_constant_offset (TREE_OPERAND (exp, 0), &var0, &off0);
519 split_constant_offset (TREE_OPERAND (exp, 1), &var1, &off1);
520 *var = fold_convert (type, fold_build2 (TREE_CODE (exp), otype,
522 *off = size_binop (code, off0, off1);
526 off1 = TREE_OPERAND (exp, 1);
527 if (TREE_CODE (off1) != INTEGER_CST)
530 split_constant_offset (TREE_OPERAND (exp, 0), &var0, &off0);
531 *var = fold_convert (type, fold_build2 (MULT_EXPR, otype,
533 *off = size_binop (MULT_EXPR, off0, fold_convert (ssizetype, off1));
538 tree op, base, poffset;
539 HOST_WIDE_INT pbitsize, pbitpos;
540 enum machine_mode pmode;
541 int punsignedp, pvolatilep;
543 op = TREE_OPERAND (exp, 0);
544 if (!handled_component_p (op))
547 base = get_inner_reference (op, &pbitsize, &pbitpos, &poffset,
548 &pmode, &punsignedp, &pvolatilep, false);
550 if (pbitpos % BITS_PER_UNIT != 0)
552 base = build_fold_addr_expr (base);
553 off0 = ssize_int (pbitpos / BITS_PER_UNIT);
557 split_constant_offset (poffset, &poffset, &off1);
558 off0 = size_binop (PLUS_EXPR, off0, off1);
559 base = fold_build2 (PLUS_EXPR, TREE_TYPE (base),
561 fold_convert (TREE_TYPE (base), poffset));
564 *var = fold_convert (type, base);
573 *off = ssize_int (0);
576 /* Returns the address ADDR of an object in a canonical shape (without nop
577 casts, and with type of pointer to the object). */
580 canonicalize_base_object_address (tree addr)
586 /* The base address may be obtained by casting from integer, in that case
588 if (!POINTER_TYPE_P (TREE_TYPE (addr)))
591 if (TREE_CODE (addr) != ADDR_EXPR)
594 return build_fold_addr_expr (TREE_OPERAND (addr, 0));
597 /* Analyzes the behavior of the memory reference DR in the innermost loop that
601 dr_analyze_innermost (struct data_reference *dr)
603 tree stmt = DR_STMT (dr);
604 struct loop *loop = loop_containing_stmt (stmt);
605 tree ref = DR_REF (dr);
606 HOST_WIDE_INT pbitsize, pbitpos;
608 enum machine_mode pmode;
609 int punsignedp, pvolatilep;
610 affine_iv base_iv, offset_iv;
611 tree init, dinit, step;
613 if (dump_file && (dump_flags & TDF_DETAILS))
614 fprintf (dump_file, "analyze_innermost: ");
616 base = get_inner_reference (ref, &pbitsize, &pbitpos, &poffset,
617 &pmode, &punsignedp, &pvolatilep, false);
618 gcc_assert (base != NULL_TREE);
620 if (pbitpos % BITS_PER_UNIT != 0)
622 if (dump_file && (dump_flags & TDF_DETAILS))
623 fprintf (dump_file, "failed: bit offset alignment.\n");
627 base = build_fold_addr_expr (base);
628 if (!simple_iv (loop, stmt, base, &base_iv, false))
630 if (dump_file && (dump_flags & TDF_DETAILS))
631 fprintf (dump_file, "failed: evolution of base is not affine.\n");
636 offset_iv.base = ssize_int (0);
637 offset_iv.step = ssize_int (0);
639 else if (!simple_iv (loop, stmt, poffset, &offset_iv, false))
641 if (dump_file && (dump_flags & TDF_DETAILS))
642 fprintf (dump_file, "failed: evolution of offset is not affine.\n");
646 init = ssize_int (pbitpos / BITS_PER_UNIT);
647 split_constant_offset (base_iv.base, &base_iv.base, &dinit);
648 init = size_binop (PLUS_EXPR, init, dinit);
649 split_constant_offset (offset_iv.base, &offset_iv.base, &dinit);
650 init = size_binop (PLUS_EXPR, init, dinit);
652 step = size_binop (PLUS_EXPR,
653 fold_convert (ssizetype, base_iv.step),
654 fold_convert (ssizetype, offset_iv.step));
656 DR_BASE_ADDRESS (dr) = canonicalize_base_object_address (base_iv.base);
658 DR_OFFSET (dr) = fold_convert (ssizetype, offset_iv.base);
662 DR_ALIGNED_TO (dr) = size_int (highest_pow2_factor (offset_iv.base));
664 if (dump_file && (dump_flags & TDF_DETAILS))
665 fprintf (dump_file, "success.\n");
668 /* Determines the base object and the list of indices of memory reference
669 DR, analyzed in loop nest NEST. */
672 dr_analyze_indices (struct data_reference *dr, struct loop *nest)
674 tree stmt = DR_STMT (dr);
675 struct loop *loop = loop_containing_stmt (stmt);
676 VEC (tree, heap) *access_fns = NULL;
677 tree ref = unshare_expr (DR_REF (dr)), aref = ref, op;
678 tree base, off, access_fn;
680 while (handled_component_p (aref))
682 if (TREE_CODE (aref) == ARRAY_REF)
684 op = TREE_OPERAND (aref, 1);
685 access_fn = analyze_scalar_evolution (loop, op);
686 access_fn = resolve_mixers (nest, access_fn);
687 VEC_safe_push (tree, heap, access_fns, access_fn);
689 TREE_OPERAND (aref, 1) = build_int_cst (TREE_TYPE (op), 0);
692 aref = TREE_OPERAND (aref, 0);
695 if (INDIRECT_REF_P (aref))
697 op = TREE_OPERAND (aref, 0);
698 access_fn = analyze_scalar_evolution (loop, op);
699 access_fn = resolve_mixers (nest, access_fn);
700 base = initial_condition (access_fn);
701 split_constant_offset (base, &base, &off);
702 access_fn = chrec_replace_initial_condition (access_fn,
703 fold_convert (TREE_TYPE (base), off));
705 TREE_OPERAND (aref, 0) = base;
706 VEC_safe_push (tree, heap, access_fns, access_fn);
709 DR_BASE_OBJECT (dr) = ref;
710 DR_ACCESS_FNS (dr) = access_fns;
713 /* Extracts the alias analysis information from the memory reference DR. */
716 dr_analyze_alias (struct data_reference *dr)
718 tree stmt = DR_STMT (dr);
719 tree ref = DR_REF (dr);
720 tree base = get_base_address (ref), addr, smt = NULL_TREE;
727 else if (INDIRECT_REF_P (base))
729 addr = TREE_OPERAND (base, 0);
730 if (TREE_CODE (addr) == SSA_NAME)
732 smt = symbol_mem_tag (SSA_NAME_VAR (addr));
733 DR_PTR_INFO (dr) = SSA_NAME_PTR_INFO (addr);
737 DR_SYMBOL_TAG (dr) = smt;
738 if (smt && var_can_have_subvars (smt))
739 DR_SUBVARS (dr) = get_subvars_for_var (smt);
741 vops = BITMAP_ALLOC (NULL);
742 FOR_EACH_SSA_TREE_OPERAND (op, stmt, it, SSA_OP_VIRTUAL_USES)
744 bitmap_set_bit (vops, DECL_UID (SSA_NAME_VAR (op)));
750 /* Returns true if the address of DR is invariant. */
753 dr_address_invariant_p (struct data_reference *dr)
758 for (i = 0; VEC_iterate (tree, DR_ACCESS_FNS (dr), i, idx); i++)
759 if (tree_contains_chrecs (idx, NULL))
765 /* Frees data reference DR. */
768 free_data_ref (data_reference_p dr)
770 BITMAP_FREE (DR_VOPS (dr));
771 VEC_free (tree, heap, DR_ACCESS_FNS (dr));
775 /* Analyzes memory reference MEMREF accessed in STMT. The reference
776 is read if IS_READ is true, write otherwise. Returns the
777 data_reference description of MEMREF. NEST is the outermost loop of the
778 loop nest in that the reference should be analyzed. */
780 struct data_reference *
781 create_data_ref (struct loop *nest, tree memref, tree stmt, bool is_read)
783 struct data_reference *dr;
785 if (dump_file && (dump_flags & TDF_DETAILS))
787 fprintf (dump_file, "Creating dr for ");
788 print_generic_expr (dump_file, memref, TDF_SLIM);
789 fprintf (dump_file, "\n");
792 dr = XCNEW (struct data_reference);
794 DR_REF (dr) = memref;
795 DR_IS_READ (dr) = is_read;
797 dr_analyze_innermost (dr);
798 dr_analyze_indices (dr, nest);
799 dr_analyze_alias (dr);
801 if (dump_file && (dump_flags & TDF_DETAILS))
803 fprintf (dump_file, "\tbase_address: ");
804 print_generic_expr (dump_file, DR_BASE_ADDRESS (dr), TDF_SLIM);
805 fprintf (dump_file, "\n\toffset from base address: ");
806 print_generic_expr (dump_file, DR_OFFSET (dr), TDF_SLIM);
807 fprintf (dump_file, "\n\tconstant offset from base address: ");
808 print_generic_expr (dump_file, DR_INIT (dr), TDF_SLIM);
809 fprintf (dump_file, "\n\tstep: ");
810 print_generic_expr (dump_file, DR_STEP (dr), TDF_SLIM);
811 fprintf (dump_file, "\n\taligned to: ");
812 print_generic_expr (dump_file, DR_ALIGNED_TO (dr), TDF_SLIM);
813 fprintf (dump_file, "\n\tbase_object: ");
814 print_generic_expr (dump_file, DR_BASE_OBJECT (dr), TDF_SLIM);
815 fprintf (dump_file, "\n\tsymbol tag: ");
816 print_generic_expr (dump_file, DR_SYMBOL_TAG (dr), TDF_SLIM);
817 fprintf (dump_file, "\n");
823 /* Returns true if FNA == FNB. */
826 affine_function_equal_p (affine_fn fna, affine_fn fnb)
828 unsigned i, n = VEC_length (tree, fna);
830 if (n != VEC_length (tree, fnb))
833 for (i = 0; i < n; i++)
834 if (!operand_equal_p (VEC_index (tree, fna, i),
835 VEC_index (tree, fnb, i), 0))
841 /* If all the functions in CF are the same, returns one of them,
842 otherwise returns NULL. */
845 common_affine_function (conflict_function *cf)
850 if (!CF_NONTRIVIAL_P (cf))
855 for (i = 1; i < cf->n; i++)
856 if (!affine_function_equal_p (comm, cf->fns[i]))
862 /* Returns the base of the affine function FN. */
865 affine_function_base (affine_fn fn)
867 return VEC_index (tree, fn, 0);
870 /* Returns true if FN is a constant. */
873 affine_function_constant_p (affine_fn fn)
878 for (i = 1; VEC_iterate (tree, fn, i, coef); i++)
879 if (!integer_zerop (coef))
885 /* Returns true if FN is the zero constant function. */
888 affine_function_zero_p (affine_fn fn)
890 return (integer_zerop (affine_function_base (fn))
891 && affine_function_constant_p (fn));
894 /* Applies operation OP on affine functions FNA and FNB, and returns the
898 affine_fn_op (enum tree_code op, affine_fn fna, affine_fn fnb)
904 if (VEC_length (tree, fnb) > VEC_length (tree, fna))
906 n = VEC_length (tree, fna);
907 m = VEC_length (tree, fnb);
911 n = VEC_length (tree, fnb);
912 m = VEC_length (tree, fna);
915 ret = VEC_alloc (tree, heap, m);
916 for (i = 0; i < n; i++)
917 VEC_quick_push (tree, ret,
918 fold_build2 (op, integer_type_node,
919 VEC_index (tree, fna, i),
920 VEC_index (tree, fnb, i)));
922 for (; VEC_iterate (tree, fna, i, coef); i++)
923 VEC_quick_push (tree, ret,
924 fold_build2 (op, integer_type_node,
925 coef, integer_zero_node));
926 for (; VEC_iterate (tree, fnb, i, coef); i++)
927 VEC_quick_push (tree, ret,
928 fold_build2 (op, integer_type_node,
929 integer_zero_node, coef));
934 /* Returns the sum of affine functions FNA and FNB. */
937 affine_fn_plus (affine_fn fna, affine_fn fnb)
939 return affine_fn_op (PLUS_EXPR, fna, fnb);
942 /* Returns the difference of affine functions FNA and FNB. */
945 affine_fn_minus (affine_fn fna, affine_fn fnb)
947 return affine_fn_op (MINUS_EXPR, fna, fnb);
950 /* Frees affine function FN. */
953 affine_fn_free (affine_fn fn)
955 VEC_free (tree, heap, fn);
958 /* Determine for each subscript in the data dependence relation DDR
962 compute_subscript_distance (struct data_dependence_relation *ddr)
964 conflict_function *cf_a, *cf_b;
965 affine_fn fn_a, fn_b, diff;
967 if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE)
971 for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++)
973 struct subscript *subscript;
975 subscript = DDR_SUBSCRIPT (ddr, i);
976 cf_a = SUB_CONFLICTS_IN_A (subscript);
977 cf_b = SUB_CONFLICTS_IN_B (subscript);
979 fn_a = common_affine_function (cf_a);
980 fn_b = common_affine_function (cf_b);
983 SUB_DISTANCE (subscript) = chrec_dont_know;
986 diff = affine_fn_minus (fn_a, fn_b);
988 if (affine_function_constant_p (diff))
989 SUB_DISTANCE (subscript) = affine_function_base (diff);
991 SUB_DISTANCE (subscript) = chrec_dont_know;
993 affine_fn_free (diff);
998 /* Returns the conflict function for "unknown". */
1000 static conflict_function *
1001 conflict_fn_not_known (void)
1003 conflict_function *fn = XCNEW (conflict_function);
1009 /* Returns the conflict function for "independent". */
1011 static conflict_function *
1012 conflict_fn_no_dependence (void)
1014 conflict_function *fn = XCNEW (conflict_function);
1015 fn->n = NO_DEPENDENCE;
1020 /* Returns true if the address of OBJ is invariant in LOOP. */
1023 object_address_invariant_in_loop_p (struct loop *loop, tree obj)
1025 while (handled_component_p (obj))
1027 if (TREE_CODE (obj) == ARRAY_REF)
1029 /* Index of the ARRAY_REF was zeroed in analyze_indices, thus we only
1030 need to check the stride and the lower bound of the reference. */
1031 if (chrec_contains_symbols_defined_in_loop (TREE_OPERAND (obj, 2),
1033 || chrec_contains_symbols_defined_in_loop (TREE_OPERAND (obj, 3),
1037 else if (TREE_CODE (obj) == COMPONENT_REF)
1039 if (chrec_contains_symbols_defined_in_loop (TREE_OPERAND (obj, 2),
1043 obj = TREE_OPERAND (obj, 0);
1046 if (!INDIRECT_REF_P (obj))
1049 return !chrec_contains_symbols_defined_in_loop (TREE_OPERAND (obj, 0),
1053 /* Returns true if A and B are accesses to different objects, or to different
1054 fields of the same object. */
1057 disjoint_objects_p (tree a, tree b)
1059 tree base_a, base_b;
1060 VEC (tree, heap) *comp_a = NULL, *comp_b = NULL;
1063 base_a = get_base_address (a);
1064 base_b = get_base_address (b);
1068 && base_a != base_b)
1071 if (!operand_equal_p (base_a, base_b, 0))
1074 /* Compare the component references of A and B. We must start from the inner
1075 ones, so record them to the vector first. */
1076 while (handled_component_p (a))
1078 VEC_safe_push (tree, heap, comp_a, a);
1079 a = TREE_OPERAND (a, 0);
1081 while (handled_component_p (b))
1083 VEC_safe_push (tree, heap, comp_b, b);
1084 b = TREE_OPERAND (b, 0);
1090 if (VEC_length (tree, comp_a) == 0
1091 || VEC_length (tree, comp_b) == 0)
1094 a = VEC_pop (tree, comp_a);
1095 b = VEC_pop (tree, comp_b);
1097 /* Real and imaginary part of a variable do not alias. */
1098 if ((TREE_CODE (a) == REALPART_EXPR
1099 && TREE_CODE (b) == IMAGPART_EXPR)
1100 || (TREE_CODE (a) == IMAGPART_EXPR
1101 && TREE_CODE (b) == REALPART_EXPR))
1107 if (TREE_CODE (a) != TREE_CODE (b))
1110 /* Nothing to do for ARRAY_REFs, as the indices of array_refs in
1111 DR_BASE_OBJECT are always zero. */
1112 if (TREE_CODE (a) == ARRAY_REF)
1114 else if (TREE_CODE (a) == COMPONENT_REF)
1116 if (operand_equal_p (TREE_OPERAND (a, 1), TREE_OPERAND (b, 1), 0))
1119 /* Different fields of unions may overlap. */
1120 base_a = TREE_OPERAND (a, 0);
1121 if (TREE_CODE (TREE_TYPE (base_a)) == UNION_TYPE)
1124 /* Different fields of structures cannot. */
1132 VEC_free (tree, heap, comp_a);
1133 VEC_free (tree, heap, comp_b);
1138 /* Returns false if we can prove that data references A and B do not alias,
1142 dr_may_alias_p (struct data_reference *a, struct data_reference *b)
1144 tree addr_a = DR_BASE_ADDRESS (a);
1145 tree addr_b = DR_BASE_ADDRESS (b);
1146 tree type_a, type_b;
1147 tree decl_a = NULL_TREE, decl_b = NULL_TREE;
1149 /* If the sets of virtual operands are disjoint, the memory references do not
1151 if (!bitmap_intersect_p (DR_VOPS (a), DR_VOPS (b)))
1154 /* If the accessed objects are disjoint, the memory references do not
1156 if (disjoint_objects_p (DR_BASE_OBJECT (a), DR_BASE_OBJECT (b)))
1159 if (!addr_a || !addr_b)
1162 /* If the references are based on different static objects, they cannot alias
1163 (PTA should be able to disambiguate such accesses, but often it fails to,
1164 since currently we cannot distinguish between pointer and offset in pointer
1166 if (TREE_CODE (addr_a) == ADDR_EXPR
1167 && TREE_CODE (addr_b) == ADDR_EXPR)
1168 return TREE_OPERAND (addr_a, 0) == TREE_OPERAND (addr_b, 0);
1170 /* An instruction writing through a restricted pointer is "independent" of any
1171 instruction reading or writing through a different restricted pointer,
1172 in the same block/scope. */
1174 type_a = TREE_TYPE (addr_a);
1175 type_b = TREE_TYPE (addr_b);
1176 gcc_assert (POINTER_TYPE_P (type_a) && POINTER_TYPE_P (type_b));
1178 if (TREE_CODE (addr_a) == SSA_NAME)
1179 decl_a = SSA_NAME_VAR (addr_a);
1180 if (TREE_CODE (addr_b) == SSA_NAME)
1181 decl_b = SSA_NAME_VAR (addr_b);
1183 if (TYPE_RESTRICT (type_a) && TYPE_RESTRICT (type_b)
1184 && (!DR_IS_READ (a) || !DR_IS_READ (b))
1185 && decl_a && DECL_P (decl_a)
1186 && decl_b && DECL_P (decl_b)
1188 && TREE_CODE (DECL_CONTEXT (decl_a)) == FUNCTION_DECL
1189 && DECL_CONTEXT (decl_a) == DECL_CONTEXT (decl_b))
1195 /* Initialize a data dependence relation between data accesses A and
1196 B. NB_LOOPS is the number of loops surrounding the references: the
1197 size of the classic distance/direction vectors. */
1199 static struct data_dependence_relation *
1200 initialize_data_dependence_relation (struct data_reference *a,
1201 struct data_reference *b,
1202 VEC (loop_p, heap) *loop_nest)
1204 struct data_dependence_relation *res;
1207 res = XNEW (struct data_dependence_relation);
1210 DDR_LOOP_NEST (res) = NULL;
1212 if (a == NULL || b == NULL)
1214 DDR_ARE_DEPENDENT (res) = chrec_dont_know;
1218 /* If the data references do not alias, then they are independent. */
1219 if (!dr_may_alias_p (a, b))
1221 DDR_ARE_DEPENDENT (res) = chrec_known;
1225 /* If the references do not access the same object, we do not know
1226 whether they alias or not. */
1227 if (!operand_equal_p (DR_BASE_OBJECT (a), DR_BASE_OBJECT (b), 0))
1229 DDR_ARE_DEPENDENT (res) = chrec_dont_know;
1233 /* If the base of the object is not invariant in the loop nest, we cannot
1234 analyze it. TODO -- in fact, it would suffice to record that there may
1235 be arbitrary dependences in the loops where the base object varies. */
1236 if (!object_address_invariant_in_loop_p (VEC_index (loop_p, loop_nest, 0),
1237 DR_BASE_OBJECT (a)))
1239 DDR_ARE_DEPENDENT (res) = chrec_dont_know;
1243 gcc_assert (DR_NUM_DIMENSIONS (a) == DR_NUM_DIMENSIONS (b));
1245 DDR_AFFINE_P (res) = true;
1246 DDR_ARE_DEPENDENT (res) = NULL_TREE;
1247 DDR_SUBSCRIPTS (res) = VEC_alloc (subscript_p, heap, DR_NUM_DIMENSIONS (a));
1248 DDR_LOOP_NEST (res) = loop_nest;
1249 DDR_INNER_LOOP (res) = 0;
1250 DDR_DIR_VECTS (res) = NULL;
1251 DDR_DIST_VECTS (res) = NULL;
1253 for (i = 0; i < DR_NUM_DIMENSIONS (a); i++)
1255 struct subscript *subscript;
1257 subscript = XNEW (struct subscript);
1258 SUB_CONFLICTS_IN_A (subscript) = conflict_fn_not_known ();
1259 SUB_CONFLICTS_IN_B (subscript) = conflict_fn_not_known ();
1260 SUB_LAST_CONFLICT (subscript) = chrec_dont_know;
1261 SUB_DISTANCE (subscript) = chrec_dont_know;
1262 VEC_safe_push (subscript_p, heap, DDR_SUBSCRIPTS (res), subscript);
1268 /* Frees memory used by the conflict function F. */
1271 free_conflict_function (conflict_function *f)
1275 if (CF_NONTRIVIAL_P (f))
1277 for (i = 0; i < f->n; i++)
1278 affine_fn_free (f->fns[i]);
1283 /* Frees memory used by SUBSCRIPTS. */
1286 free_subscripts (VEC (subscript_p, heap) *subscripts)
1291 for (i = 0; VEC_iterate (subscript_p, subscripts, i, s); i++)
1293 free_conflict_function (s->conflicting_iterations_in_a);
1294 free_conflict_function (s->conflicting_iterations_in_b);
1296 VEC_free (subscript_p, heap, subscripts);
1299 /* Set DDR_ARE_DEPENDENT to CHREC and finalize the subscript overlap
1303 finalize_ddr_dependent (struct data_dependence_relation *ddr,
1306 if (dump_file && (dump_flags & TDF_DETAILS))
1308 fprintf (dump_file, "(dependence classified: ");
1309 print_generic_expr (dump_file, chrec, 0);
1310 fprintf (dump_file, ")\n");
1313 DDR_ARE_DEPENDENT (ddr) = chrec;
1314 free_subscripts (DDR_SUBSCRIPTS (ddr));
1317 /* The dependence relation DDR cannot be represented by a distance
1321 non_affine_dependence_relation (struct data_dependence_relation *ddr)
1323 if (dump_file && (dump_flags & TDF_DETAILS))
1324 fprintf (dump_file, "(Dependence relation cannot be represented by distance vector.) \n");
1326 DDR_AFFINE_P (ddr) = false;
1331 /* This section contains the classic Banerjee tests. */
1333 /* Returns true iff CHREC_A and CHREC_B are not dependent on any index
1334 variables, i.e., if the ZIV (Zero Index Variable) test is true. */
1337 ziv_subscript_p (tree chrec_a,
1340 return (evolution_function_is_constant_p (chrec_a)
1341 && evolution_function_is_constant_p (chrec_b));
1344 /* Returns true iff CHREC_A and CHREC_B are dependent on an index
1345 variable, i.e., if the SIV (Single Index Variable) test is true. */
1348 siv_subscript_p (tree chrec_a,
1351 if ((evolution_function_is_constant_p (chrec_a)
1352 && evolution_function_is_univariate_p (chrec_b))
1353 || (evolution_function_is_constant_p (chrec_b)
1354 && evolution_function_is_univariate_p (chrec_a)))
1357 if (evolution_function_is_univariate_p (chrec_a)
1358 && evolution_function_is_univariate_p (chrec_b))
1360 switch (TREE_CODE (chrec_a))
1362 case POLYNOMIAL_CHREC:
1363 switch (TREE_CODE (chrec_b))
1365 case POLYNOMIAL_CHREC:
1366 if (CHREC_VARIABLE (chrec_a) != CHREC_VARIABLE (chrec_b))
1381 /* Creates a conflict function with N dimensions. The affine functions
1382 in each dimension follow. */
1384 static conflict_function *
1385 conflict_fn (unsigned n, ...)
1388 conflict_function *ret = XCNEW (conflict_function);
1391 gcc_assert (0 < n && n <= MAX_DIM);
1395 for (i = 0; i < n; i++)
1396 ret->fns[i] = va_arg (ap, affine_fn);
1402 /* Returns constant affine function with value CST. */
1405 affine_fn_cst (tree cst)
1407 affine_fn fn = VEC_alloc (tree, heap, 1);
1408 VEC_quick_push (tree, fn, cst);
1412 /* Returns affine function with single variable, CST + COEF * x_DIM. */
1415 affine_fn_univar (tree cst, unsigned dim, tree coef)
1417 affine_fn fn = VEC_alloc (tree, heap, dim + 1);
1420 gcc_assert (dim > 0);
1421 VEC_quick_push (tree, fn, cst);
1422 for (i = 1; i < dim; i++)
1423 VEC_quick_push (tree, fn, integer_zero_node);
1424 VEC_quick_push (tree, fn, coef);
1428 /* Analyze a ZIV (Zero Index Variable) subscript. *OVERLAPS_A and
1429 *OVERLAPS_B are initialized to the functions that describe the
1430 relation between the elements accessed twice by CHREC_A and
1431 CHREC_B. For k >= 0, the following property is verified:
1433 CHREC_A (*OVERLAPS_A (k)) = CHREC_B (*OVERLAPS_B (k)). */
1436 analyze_ziv_subscript (tree chrec_a,
1438 conflict_function **overlaps_a,
1439 conflict_function **overlaps_b,
1440 tree *last_conflicts)
1443 dependence_stats.num_ziv++;
1445 if (dump_file && (dump_flags & TDF_DETAILS))
1446 fprintf (dump_file, "(analyze_ziv_subscript \n");
1448 chrec_a = chrec_convert (integer_type_node, chrec_a, NULL_TREE);
1449 chrec_b = chrec_convert (integer_type_node, chrec_b, NULL_TREE);
1450 difference = chrec_fold_minus (integer_type_node, chrec_a, chrec_b);
1452 switch (TREE_CODE (difference))
1455 if (integer_zerop (difference))
1457 /* The difference is equal to zero: the accessed index
1458 overlaps for each iteration in the loop. */
1459 *overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node));
1460 *overlaps_b = conflict_fn (1, affine_fn_cst (integer_zero_node));
1461 *last_conflicts = chrec_dont_know;
1462 dependence_stats.num_ziv_dependent++;
1466 /* The accesses do not overlap. */
1467 *overlaps_a = conflict_fn_no_dependence ();
1468 *overlaps_b = conflict_fn_no_dependence ();
1469 *last_conflicts = integer_zero_node;
1470 dependence_stats.num_ziv_independent++;
1475 /* We're not sure whether the indexes overlap. For the moment,
1476 conservatively answer "don't know". */
1477 if (dump_file && (dump_flags & TDF_DETAILS))
1478 fprintf (dump_file, "ziv test failed: difference is non-integer.\n");
1480 *overlaps_a = conflict_fn_not_known ();
1481 *overlaps_b = conflict_fn_not_known ();
1482 *last_conflicts = chrec_dont_know;
1483 dependence_stats.num_ziv_unimplemented++;
1487 if (dump_file && (dump_flags & TDF_DETAILS))
1488 fprintf (dump_file, ")\n");
1491 /* Sets NIT to the estimated number of executions of the statements in
1492 LOOP. If CONSERVATIVE is true, we must be sure that NIT is at least as
1493 large as the number of iterations. If we have no reliable estimate,
1494 the function returns false, otherwise returns true. */
1497 estimated_loop_iterations (struct loop *loop, bool conservative,
1500 estimate_numbers_of_iterations_loop (loop);
1503 if (!loop->any_upper_bound)
1506 *nit = loop->nb_iterations_upper_bound;
1510 if (!loop->any_estimate)
1513 *nit = loop->nb_iterations_estimate;
1519 /* Similar to estimated_loop_iterations, but returns the estimate only
1520 if it fits to HOST_WIDE_INT. If this is not the case, or the estimate
1521 on the number of iterations of LOOP could not be derived, returns -1. */
1524 estimated_loop_iterations_int (struct loop *loop, bool conservative)
1527 HOST_WIDE_INT hwi_nit;
1529 if (!estimated_loop_iterations (loop, conservative, &nit))
1532 if (!double_int_fits_in_shwi_p (nit))
1534 hwi_nit = double_int_to_shwi (nit);
1536 return hwi_nit < 0 ? -1 : hwi_nit;
1539 /* Similar to estimated_loop_iterations, but returns the estimate as a tree,
1540 and only if it fits to the int type. If this is not the case, or the
1541 estimate on the number of iterations of LOOP could not be derived, returns
1545 estimated_loop_iterations_tree (struct loop *loop, bool conservative)
1550 if (!estimated_loop_iterations (loop, conservative, &nit))
1551 return chrec_dont_know;
1553 type = lang_hooks.types.type_for_size (INT_TYPE_SIZE, true);
1554 if (!double_int_fits_to_tree_p (type, nit))
1555 return chrec_dont_know;
1557 return double_int_to_tree (type, nit);
1560 /* Analyze a SIV (Single Index Variable) subscript where CHREC_A is a
1561 constant, and CHREC_B is an affine function. *OVERLAPS_A and
1562 *OVERLAPS_B are initialized to the functions that describe the
1563 relation between the elements accessed twice by CHREC_A and
1564 CHREC_B. For k >= 0, the following property is verified:
1566 CHREC_A (*OVERLAPS_A (k)) = CHREC_B (*OVERLAPS_B (k)). */
1569 analyze_siv_subscript_cst_affine (tree chrec_a,
1571 conflict_function **overlaps_a,
1572 conflict_function **overlaps_b,
1573 tree *last_conflicts)
1575 bool value0, value1, value2;
1576 tree difference, tmp;
1578 chrec_a = chrec_convert (integer_type_node, chrec_a, NULL_TREE);
1579 chrec_b = chrec_convert (integer_type_node, chrec_b, NULL_TREE);
1580 difference = chrec_fold_minus
1581 (integer_type_node, initial_condition (chrec_b), chrec_a);
1583 if (!chrec_is_positive (initial_condition (difference), &value0))
1585 if (dump_file && (dump_flags & TDF_DETAILS))
1586 fprintf (dump_file, "siv test failed: chrec is not positive.\n");
1588 dependence_stats.num_siv_unimplemented++;
1589 *overlaps_a = conflict_fn_not_known ();
1590 *overlaps_b = conflict_fn_not_known ();
1591 *last_conflicts = chrec_dont_know;
1596 if (value0 == false)
1598 if (!chrec_is_positive (CHREC_RIGHT (chrec_b), &value1))
1600 if (dump_file && (dump_flags & TDF_DETAILS))
1601 fprintf (dump_file, "siv test failed: chrec not positive.\n");
1603 *overlaps_a = conflict_fn_not_known ();
1604 *overlaps_b = conflict_fn_not_known ();
1605 *last_conflicts = chrec_dont_know;
1606 dependence_stats.num_siv_unimplemented++;
1615 chrec_b = {10, +, 1}
1618 if (tree_fold_divides_p (CHREC_RIGHT (chrec_b), difference))
1620 HOST_WIDE_INT numiter;
1621 struct loop *loop = get_chrec_loop (chrec_b);
1623 *overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node));
1624 tmp = fold_build2 (EXACT_DIV_EXPR, integer_type_node,
1625 fold_build1 (ABS_EXPR,
1628 CHREC_RIGHT (chrec_b));
1629 *overlaps_b = conflict_fn (1, affine_fn_cst (tmp));
1630 *last_conflicts = integer_one_node;
1633 /* Perform weak-zero siv test to see if overlap is
1634 outside the loop bounds. */
1635 numiter = estimated_loop_iterations_int (loop, false);
1638 && compare_tree_int (tmp, numiter) > 0)
1640 free_conflict_function (*overlaps_a);
1641 free_conflict_function (*overlaps_b);
1642 *overlaps_a = conflict_fn_no_dependence ();
1643 *overlaps_b = conflict_fn_no_dependence ();
1644 *last_conflicts = integer_zero_node;
1645 dependence_stats.num_siv_independent++;
1648 dependence_stats.num_siv_dependent++;
1652 /* When the step does not divide the difference, there are
1656 *overlaps_a = conflict_fn_no_dependence ();
1657 *overlaps_b = conflict_fn_no_dependence ();
1658 *last_conflicts = integer_zero_node;
1659 dependence_stats.num_siv_independent++;
1668 chrec_b = {10, +, -1}
1670 In this case, chrec_a will not overlap with chrec_b. */
1671 *overlaps_a = conflict_fn_no_dependence ();
1672 *overlaps_b = conflict_fn_no_dependence ();
1673 *last_conflicts = integer_zero_node;
1674 dependence_stats.num_siv_independent++;
1681 if (!chrec_is_positive (CHREC_RIGHT (chrec_b), &value2))
1683 if (dump_file && (dump_flags & TDF_DETAILS))
1684 fprintf (dump_file, "siv test failed: chrec not positive.\n");
1686 *overlaps_a = conflict_fn_not_known ();
1687 *overlaps_b = conflict_fn_not_known ();
1688 *last_conflicts = chrec_dont_know;
1689 dependence_stats.num_siv_unimplemented++;
1694 if (value2 == false)
1698 chrec_b = {10, +, -1}
1700 if (tree_fold_divides_p (CHREC_RIGHT (chrec_b), difference))
1702 HOST_WIDE_INT numiter;
1703 struct loop *loop = get_chrec_loop (chrec_b);
1705 *overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node));
1706 tmp = fold_build2 (EXACT_DIV_EXPR,
1707 integer_type_node, difference,
1708 CHREC_RIGHT (chrec_b));
1709 *overlaps_b = conflict_fn (1, affine_fn_cst (tmp));
1710 *last_conflicts = integer_one_node;
1712 /* Perform weak-zero siv test to see if overlap is
1713 outside the loop bounds. */
1714 numiter = estimated_loop_iterations_int (loop, false);
1717 && compare_tree_int (tmp, numiter) > 0)
1719 free_conflict_function (*overlaps_a);
1720 free_conflict_function (*overlaps_b);
1721 *overlaps_a = conflict_fn_no_dependence ();
1722 *overlaps_b = conflict_fn_no_dependence ();
1723 *last_conflicts = integer_zero_node;
1724 dependence_stats.num_siv_independent++;
1727 dependence_stats.num_siv_dependent++;
1731 /* When the step does not divide the difference, there
1735 *overlaps_a = conflict_fn_no_dependence ();
1736 *overlaps_b = conflict_fn_no_dependence ();
1737 *last_conflicts = integer_zero_node;
1738 dependence_stats.num_siv_independent++;
1748 In this case, chrec_a will not overlap with chrec_b. */
1749 *overlaps_a = conflict_fn_no_dependence ();
1750 *overlaps_b = conflict_fn_no_dependence ();
1751 *last_conflicts = integer_zero_node;
1752 dependence_stats.num_siv_independent++;
1760 /* Helper recursive function for initializing the matrix A. Returns
1761 the initial value of CHREC. */
1764 initialize_matrix_A (lambda_matrix A, tree chrec, unsigned index, int mult)
1768 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
1769 return int_cst_value (chrec);
1771 A[index][0] = mult * int_cst_value (CHREC_RIGHT (chrec));
1772 return initialize_matrix_A (A, CHREC_LEFT (chrec), index + 1, mult);
1775 #define FLOOR_DIV(x,y) ((x) / (y))
1777 /* Solves the special case of the Diophantine equation:
1778 | {0, +, STEP_A}_x (OVERLAPS_A) = {0, +, STEP_B}_y (OVERLAPS_B)
1780 Computes the descriptions OVERLAPS_A and OVERLAPS_B. NITER is the
1781 number of iterations that loops X and Y run. The overlaps will be
1782 constructed as evolutions in dimension DIM. */
1785 compute_overlap_steps_for_affine_univar (int niter, int step_a, int step_b,
1786 affine_fn *overlaps_a,
1787 affine_fn *overlaps_b,
1788 tree *last_conflicts, int dim)
1790 if (((step_a > 0 && step_b > 0)
1791 || (step_a < 0 && step_b < 0)))
1793 int step_overlaps_a, step_overlaps_b;
1794 int gcd_steps_a_b, last_conflict, tau2;
1796 gcd_steps_a_b = gcd (step_a, step_b);
1797 step_overlaps_a = step_b / gcd_steps_a_b;
1798 step_overlaps_b = step_a / gcd_steps_a_b;
1800 tau2 = FLOOR_DIV (niter, step_overlaps_a);
1801 tau2 = MIN (tau2, FLOOR_DIV (niter, step_overlaps_b));
1802 last_conflict = tau2;
1804 *overlaps_a = affine_fn_univar (integer_zero_node, dim,
1805 build_int_cst (NULL_TREE,
1807 *overlaps_b = affine_fn_univar (integer_zero_node, dim,
1808 build_int_cst (NULL_TREE,
1810 *last_conflicts = build_int_cst (NULL_TREE, last_conflict);
1815 *overlaps_a = affine_fn_cst (integer_zero_node);
1816 *overlaps_b = affine_fn_cst (integer_zero_node);
1817 *last_conflicts = integer_zero_node;
1821 /* Solves the special case of a Diophantine equation where CHREC_A is
1822 an affine bivariate function, and CHREC_B is an affine univariate
1823 function. For example,
1825 | {{0, +, 1}_x, +, 1335}_y = {0, +, 1336}_z
1827 has the following overlapping functions:
1829 | x (t, u, v) = {{0, +, 1336}_t, +, 1}_v
1830 | y (t, u, v) = {{0, +, 1336}_u, +, 1}_v
1831 | z (t, u, v) = {{{0, +, 1}_t, +, 1335}_u, +, 1}_v
1833 FORNOW: This is a specialized implementation for a case occurring in
1834 a common benchmark. Implement the general algorithm. */
1837 compute_overlap_steps_for_affine_1_2 (tree chrec_a, tree chrec_b,
1838 conflict_function **overlaps_a,
1839 conflict_function **overlaps_b,
1840 tree *last_conflicts)
1842 bool xz_p, yz_p, xyz_p;
1843 int step_x, step_y, step_z;
1844 HOST_WIDE_INT niter_x, niter_y, niter_z, niter;
1845 affine_fn overlaps_a_xz, overlaps_b_xz;
1846 affine_fn overlaps_a_yz, overlaps_b_yz;
1847 affine_fn overlaps_a_xyz, overlaps_b_xyz;
1848 affine_fn ova1, ova2, ovb;
1849 tree last_conflicts_xz, last_conflicts_yz, last_conflicts_xyz;
1851 step_x = int_cst_value (CHREC_RIGHT (CHREC_LEFT (chrec_a)));
1852 step_y = int_cst_value (CHREC_RIGHT (chrec_a));
1853 step_z = int_cst_value (CHREC_RIGHT (chrec_b));
1856 estimated_loop_iterations_int (get_chrec_loop (CHREC_LEFT (chrec_a)),
1858 niter_y = estimated_loop_iterations_int (get_chrec_loop (chrec_a), false);
1859 niter_z = estimated_loop_iterations_int (get_chrec_loop (chrec_b), false);
1861 if (niter_x < 0 || niter_y < 0 || niter_z < 0)
1863 if (dump_file && (dump_flags & TDF_DETAILS))
1864 fprintf (dump_file, "overlap steps test failed: no iteration counts.\n");
1866 *overlaps_a = conflict_fn_not_known ();
1867 *overlaps_b = conflict_fn_not_known ();
1868 *last_conflicts = chrec_dont_know;
1872 niter = MIN (niter_x, niter_z);
1873 compute_overlap_steps_for_affine_univar (niter, step_x, step_z,
1876 &last_conflicts_xz, 1);
1877 niter = MIN (niter_y, niter_z);
1878 compute_overlap_steps_for_affine_univar (niter, step_y, step_z,
1881 &last_conflicts_yz, 2);
1882 niter = MIN (niter_x, niter_z);
1883 niter = MIN (niter_y, niter);
1884 compute_overlap_steps_for_affine_univar (niter, step_x + step_y, step_z,
1887 &last_conflicts_xyz, 3);
1889 xz_p = !integer_zerop (last_conflicts_xz);
1890 yz_p = !integer_zerop (last_conflicts_yz);
1891 xyz_p = !integer_zerop (last_conflicts_xyz);
1893 if (xz_p || yz_p || xyz_p)
1895 ova1 = affine_fn_cst (integer_zero_node);
1896 ova2 = affine_fn_cst (integer_zero_node);
1897 ovb = affine_fn_cst (integer_zero_node);
1900 affine_fn t0 = ova1;
1903 ova1 = affine_fn_plus (ova1, overlaps_a_xz);
1904 ovb = affine_fn_plus (ovb, overlaps_b_xz);
1905 affine_fn_free (t0);
1906 affine_fn_free (t2);
1907 *last_conflicts = last_conflicts_xz;
1911 affine_fn t0 = ova2;
1914 ova2 = affine_fn_plus (ova2, overlaps_a_yz);
1915 ovb = affine_fn_plus (ovb, overlaps_b_yz);
1916 affine_fn_free (t0);
1917 affine_fn_free (t2);
1918 *last_conflicts = last_conflicts_yz;
1922 affine_fn t0 = ova1;
1923 affine_fn t2 = ova2;
1926 ova1 = affine_fn_plus (ova1, overlaps_a_xyz);
1927 ova2 = affine_fn_plus (ova2, overlaps_a_xyz);
1928 ovb = affine_fn_plus (ovb, overlaps_b_xyz);
1929 affine_fn_free (t0);
1930 affine_fn_free (t2);
1931 affine_fn_free (t4);
1932 *last_conflicts = last_conflicts_xyz;
1934 *overlaps_a = conflict_fn (2, ova1, ova2);
1935 *overlaps_b = conflict_fn (1, ovb);
1939 *overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node));
1940 *overlaps_b = conflict_fn (1, affine_fn_cst (integer_zero_node));
1941 *last_conflicts = integer_zero_node;
1944 affine_fn_free (overlaps_a_xz);
1945 affine_fn_free (overlaps_b_xz);
1946 affine_fn_free (overlaps_a_yz);
1947 affine_fn_free (overlaps_b_yz);
1948 affine_fn_free (overlaps_a_xyz);
1949 affine_fn_free (overlaps_b_xyz);
1952 /* Determines the overlapping elements due to accesses CHREC_A and
1953 CHREC_B, that are affine functions. This function cannot handle
1954 symbolic evolution functions, ie. when initial conditions are
1955 parameters, because it uses lambda matrices of integers. */
1958 analyze_subscript_affine_affine (tree chrec_a,
1960 conflict_function **overlaps_a,
1961 conflict_function **overlaps_b,
1962 tree *last_conflicts)
1964 unsigned nb_vars_a, nb_vars_b, dim;
1965 HOST_WIDE_INT init_a, init_b, gamma, gcd_alpha_beta;
1966 HOST_WIDE_INT tau1, tau2;
1967 lambda_matrix A, U, S;
1969 if (eq_evolutions_p (chrec_a, chrec_b))
1971 /* The accessed index overlaps for each iteration in the
1973 *overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node));
1974 *overlaps_b = conflict_fn (1, affine_fn_cst (integer_zero_node));
1975 *last_conflicts = chrec_dont_know;
1978 if (dump_file && (dump_flags & TDF_DETAILS))
1979 fprintf (dump_file, "(analyze_subscript_affine_affine \n");
1981 /* For determining the initial intersection, we have to solve a
1982 Diophantine equation. This is the most time consuming part.
1984 For answering to the question: "Is there a dependence?" we have
1985 to prove that there exists a solution to the Diophantine
1986 equation, and that the solution is in the iteration domain,
1987 i.e. the solution is positive or zero, and that the solution
1988 happens before the upper bound loop.nb_iterations. Otherwise
1989 there is no dependence. This function outputs a description of
1990 the iterations that hold the intersections. */
1992 nb_vars_a = nb_vars_in_chrec (chrec_a);
1993 nb_vars_b = nb_vars_in_chrec (chrec_b);
1995 dim = nb_vars_a + nb_vars_b;
1996 U = lambda_matrix_new (dim, dim);
1997 A = lambda_matrix_new (dim, 1);
1998 S = lambda_matrix_new (dim, 1);
2000 init_a = initialize_matrix_A (A, chrec_a, 0, 1);
2001 init_b = initialize_matrix_A (A, chrec_b, nb_vars_a, -1);
2002 gamma = init_b - init_a;
2004 /* Don't do all the hard work of solving the Diophantine equation
2005 when we already know the solution: for example,
2008 | gamma = 3 - 3 = 0.
2009 Then the first overlap occurs during the first iterations:
2010 | {3, +, 1}_1 ({0, +, 4}_x) = {3, +, 4}_2 ({0, +, 1}_x)
2014 if (nb_vars_a == 1 && nb_vars_b == 1)
2016 HOST_WIDE_INT step_a, step_b;
2017 HOST_WIDE_INT niter, niter_a, niter_b;
2020 niter_a = estimated_loop_iterations_int (get_chrec_loop (chrec_a),
2022 niter_b = estimated_loop_iterations_int (get_chrec_loop (chrec_b),
2024 if (niter_a < 0 || niter_b < 0)
2026 if (dump_file && (dump_flags & TDF_DETAILS))
2027 fprintf (dump_file, "affine-affine test failed: missing iteration counts.\n");
2028 *overlaps_a = conflict_fn_not_known ();
2029 *overlaps_b = conflict_fn_not_known ();
2030 *last_conflicts = chrec_dont_know;
2031 goto end_analyze_subs_aa;
2034 niter = MIN (niter_a, niter_b);
2036 step_a = int_cst_value (CHREC_RIGHT (chrec_a));
2037 step_b = int_cst_value (CHREC_RIGHT (chrec_b));
2039 compute_overlap_steps_for_affine_univar (niter, step_a, step_b,
2042 *overlaps_a = conflict_fn (1, ova);
2043 *overlaps_b = conflict_fn (1, ovb);
2046 else if (nb_vars_a == 2 && nb_vars_b == 1)
2047 compute_overlap_steps_for_affine_1_2
2048 (chrec_a, chrec_b, overlaps_a, overlaps_b, last_conflicts);
2050 else if (nb_vars_a == 1 && nb_vars_b == 2)
2051 compute_overlap_steps_for_affine_1_2
2052 (chrec_b, chrec_a, overlaps_b, overlaps_a, last_conflicts);
2056 if (dump_file && (dump_flags & TDF_DETAILS))
2057 fprintf (dump_file, "affine-affine test failed: too many variables.\n");
2058 *overlaps_a = conflict_fn_not_known ();
2059 *overlaps_b = conflict_fn_not_known ();
2060 *last_conflicts = chrec_dont_know;
2062 goto end_analyze_subs_aa;
2066 lambda_matrix_right_hermite (A, dim, 1, S, U);
2071 lambda_matrix_row_negate (U, dim, 0);
2073 gcd_alpha_beta = S[0][0];
2075 /* Something went wrong: for example in {1, +, 0}_5 vs. {0, +, 0}_5,
2076 but that is a quite strange case. Instead of ICEing, answer
2078 if (gcd_alpha_beta == 0)
2080 *overlaps_a = conflict_fn_not_known ();
2081 *overlaps_b = conflict_fn_not_known ();
2082 *last_conflicts = chrec_dont_know;
2083 goto end_analyze_subs_aa;
2086 /* The classic "gcd-test". */
2087 if (!int_divides_p (gcd_alpha_beta, gamma))
2089 /* The "gcd-test" has determined that there is no integer
2090 solution, i.e. there is no dependence. */
2091 *overlaps_a = conflict_fn_no_dependence ();
2092 *overlaps_b = conflict_fn_no_dependence ();
2093 *last_conflicts = integer_zero_node;
2096 /* Both access functions are univariate. This includes SIV and MIV cases. */
2097 else if (nb_vars_a == 1 && nb_vars_b == 1)
2099 /* Both functions should have the same evolution sign. */
2100 if (((A[0][0] > 0 && -A[1][0] > 0)
2101 || (A[0][0] < 0 && -A[1][0] < 0)))
2103 /* The solutions are given by:
2105 | [GAMMA/GCD_ALPHA_BETA t].[u11 u12] = [x0]
2108 For a given integer t. Using the following variables,
2110 | i0 = u11 * gamma / gcd_alpha_beta
2111 | j0 = u12 * gamma / gcd_alpha_beta
2118 | y0 = j0 + j1 * t. */
2120 HOST_WIDE_INT i0, j0, i1, j1;
2122 /* X0 and Y0 are the first iterations for which there is a
2123 dependence. X0, Y0 are two solutions of the Diophantine
2124 equation: chrec_a (X0) = chrec_b (Y0). */
2125 HOST_WIDE_INT x0, y0;
2126 HOST_WIDE_INT niter, niter_a, niter_b;
2128 niter_a = estimated_loop_iterations_int (get_chrec_loop (chrec_a),
2130 niter_b = estimated_loop_iterations_int (get_chrec_loop (chrec_b),
2133 if (niter_a < 0 || niter_b < 0)
2135 if (dump_file && (dump_flags & TDF_DETAILS))
2136 fprintf (dump_file, "affine-affine test failed: missing iteration counts.\n");
2137 *overlaps_a = conflict_fn_not_known ();
2138 *overlaps_b = conflict_fn_not_known ();
2139 *last_conflicts = chrec_dont_know;
2140 goto end_analyze_subs_aa;
2143 niter = MIN (niter_a, niter_b);
2145 i0 = U[0][0] * gamma / gcd_alpha_beta;
2146 j0 = U[0][1] * gamma / gcd_alpha_beta;
2150 if ((i1 == 0 && i0 < 0)
2151 || (j1 == 0 && j0 < 0))
2153 /* There is no solution.
2154 FIXME: The case "i0 > nb_iterations, j0 > nb_iterations"
2155 falls in here, but for the moment we don't look at the
2156 upper bound of the iteration domain. */
2157 *overlaps_a = conflict_fn_no_dependence ();
2158 *overlaps_b = conflict_fn_no_dependence ();
2159 *last_conflicts = integer_zero_node;
2166 tau1 = CEIL (-i0, i1);
2167 tau2 = FLOOR_DIV (niter - i0, i1);
2171 int last_conflict, min_multiple;
2172 tau1 = MAX (tau1, CEIL (-j0, j1));
2173 tau2 = MIN (tau2, FLOOR_DIV (niter - j0, j1));
2175 x0 = i1 * tau1 + i0;
2176 y0 = j1 * tau1 + j0;
2178 /* At this point (x0, y0) is one of the
2179 solutions to the Diophantine equation. The
2180 next step has to compute the smallest
2181 positive solution: the first conflicts. */
2182 min_multiple = MIN (x0 / i1, y0 / j1);
2183 x0 -= i1 * min_multiple;
2184 y0 -= j1 * min_multiple;
2186 tau1 = (x0 - i0)/i1;
2187 last_conflict = tau2 - tau1;
2189 /* If the overlap occurs outside of the bounds of the
2190 loop, there is no dependence. */
2191 if (x0 > niter || y0 > niter)
2193 *overlaps_a = conflict_fn_no_dependence ();
2194 *overlaps_b = conflict_fn_no_dependence ();
2195 *last_conflicts = integer_zero_node;
2201 affine_fn_univar (build_int_cst (NULL_TREE, x0),
2203 build_int_cst (NULL_TREE, i1)));
2206 affine_fn_univar (build_int_cst (NULL_TREE, y0),
2208 build_int_cst (NULL_TREE, j1)));
2209 *last_conflicts = build_int_cst (NULL_TREE, last_conflict);
2214 /* FIXME: For the moment, the upper bound of the
2215 iteration domain for j is not checked. */
2216 if (dump_file && (dump_flags & TDF_DETAILS))
2217 fprintf (dump_file, "affine-affine test failed: unimplemented.\n");
2218 *overlaps_a = conflict_fn_not_known ();
2219 *overlaps_b = conflict_fn_not_known ();
2220 *last_conflicts = chrec_dont_know;
2226 /* FIXME: For the moment, the upper bound of the
2227 iteration domain for i is not checked. */
2228 if (dump_file && (dump_flags & TDF_DETAILS))
2229 fprintf (dump_file, "affine-affine test failed: unimplemented.\n");
2230 *overlaps_a = conflict_fn_not_known ();
2231 *overlaps_b = conflict_fn_not_known ();
2232 *last_conflicts = chrec_dont_know;
2238 if (dump_file && (dump_flags & TDF_DETAILS))
2239 fprintf (dump_file, "affine-affine test failed: unimplemented.\n");
2240 *overlaps_a = conflict_fn_not_known ();
2241 *overlaps_b = conflict_fn_not_known ();
2242 *last_conflicts = chrec_dont_know;
2248 if (dump_file && (dump_flags & TDF_DETAILS))
2249 fprintf (dump_file, "affine-affine test failed: unimplemented.\n");
2250 *overlaps_a = conflict_fn_not_known ();
2251 *overlaps_b = conflict_fn_not_known ();
2252 *last_conflicts = chrec_dont_know;
2255 end_analyze_subs_aa:
2256 if (dump_file && (dump_flags & TDF_DETAILS))
2258 fprintf (dump_file, " (overlaps_a = ");
2259 dump_conflict_function (dump_file, *overlaps_a);
2260 fprintf (dump_file, ")\n (overlaps_b = ");
2261 dump_conflict_function (dump_file, *overlaps_b);
2262 fprintf (dump_file, ")\n");
2263 fprintf (dump_file, ")\n");
2267 /* Returns true when analyze_subscript_affine_affine can be used for
2268 determining the dependence relation between chrec_a and chrec_b,
2269 that contain symbols. This function modifies chrec_a and chrec_b
2270 such that the analysis result is the same, and such that they don't
2271 contain symbols, and then can safely be passed to the analyzer.
2273 Example: The analysis of the following tuples of evolutions produce
2274 the same results: {x+1, +, 1}_1 vs. {x+3, +, 1}_1, and {-2, +, 1}_1
2277 {x+1, +, 1}_1 ({2, +, 1}_1) = {x+3, +, 1}_1 ({0, +, 1}_1)
2278 {-2, +, 1}_1 ({2, +, 1}_1) = {0, +, 1}_1 ({0, +, 1}_1)
2282 can_use_analyze_subscript_affine_affine (tree *chrec_a, tree *chrec_b)
2284 tree diff, type, left_a, left_b, right_b;
2286 if (chrec_contains_symbols (CHREC_RIGHT (*chrec_a))
2287 || chrec_contains_symbols (CHREC_RIGHT (*chrec_b)))
2288 /* FIXME: For the moment not handled. Might be refined later. */
2291 type = chrec_type (*chrec_a);
2292 left_a = CHREC_LEFT (*chrec_a);
2293 left_b = chrec_convert (type, CHREC_LEFT (*chrec_b), NULL_TREE);
2294 diff = chrec_fold_minus (type, left_a, left_b);
2296 if (!evolution_function_is_constant_p (diff))
2299 if (dump_file && (dump_flags & TDF_DETAILS))
2300 fprintf (dump_file, "can_use_subscript_aff_aff_for_symbolic \n");
2302 *chrec_a = build_polynomial_chrec (CHREC_VARIABLE (*chrec_a),
2303 diff, CHREC_RIGHT (*chrec_a));
2304 right_b = chrec_convert (type, CHREC_RIGHT (*chrec_b), NULL_TREE);
2305 *chrec_b = build_polynomial_chrec (CHREC_VARIABLE (*chrec_b),
2306 build_int_cst (type, 0),
2311 /* Analyze a SIV (Single Index Variable) subscript. *OVERLAPS_A and
2312 *OVERLAPS_B are initialized to the functions that describe the
2313 relation between the elements accessed twice by CHREC_A and
2314 CHREC_B. For k >= 0, the following property is verified:
2316 CHREC_A (*OVERLAPS_A (k)) = CHREC_B (*OVERLAPS_B (k)). */
2319 analyze_siv_subscript (tree chrec_a,
2321 conflict_function **overlaps_a,
2322 conflict_function **overlaps_b,
2323 tree *last_conflicts)
2325 dependence_stats.num_siv++;
2327 if (dump_file && (dump_flags & TDF_DETAILS))
2328 fprintf (dump_file, "(analyze_siv_subscript \n");
2330 if (evolution_function_is_constant_p (chrec_a)
2331 && evolution_function_is_affine_p (chrec_b))
2332 analyze_siv_subscript_cst_affine (chrec_a, chrec_b,
2333 overlaps_a, overlaps_b, last_conflicts);
2335 else if (evolution_function_is_affine_p (chrec_a)
2336 && evolution_function_is_constant_p (chrec_b))
2337 analyze_siv_subscript_cst_affine (chrec_b, chrec_a,
2338 overlaps_b, overlaps_a, last_conflicts);
2340 else if (evolution_function_is_affine_p (chrec_a)
2341 && evolution_function_is_affine_p (chrec_b))
2343 if (!chrec_contains_symbols (chrec_a)
2344 && !chrec_contains_symbols (chrec_b))
2346 analyze_subscript_affine_affine (chrec_a, chrec_b,
2347 overlaps_a, overlaps_b,
2350 if (CF_NOT_KNOWN_P (*overlaps_a)
2351 || CF_NOT_KNOWN_P (*overlaps_b))
2352 dependence_stats.num_siv_unimplemented++;
2353 else if (CF_NO_DEPENDENCE_P (*overlaps_a)
2354 || CF_NO_DEPENDENCE_P (*overlaps_b))
2355 dependence_stats.num_siv_independent++;
2357 dependence_stats.num_siv_dependent++;
2359 else if (can_use_analyze_subscript_affine_affine (&chrec_a,
2362 analyze_subscript_affine_affine (chrec_a, chrec_b,
2363 overlaps_a, overlaps_b,
2366 if (CF_NOT_KNOWN_P (*overlaps_a)
2367 || CF_NOT_KNOWN_P (*overlaps_b))
2368 dependence_stats.num_siv_unimplemented++;
2369 else if (CF_NO_DEPENDENCE_P (*overlaps_a)
2370 || CF_NO_DEPENDENCE_P (*overlaps_b))
2371 dependence_stats.num_siv_independent++;
2373 dependence_stats.num_siv_dependent++;
2376 goto siv_subscript_dontknow;
2381 siv_subscript_dontknow:;
2382 if (dump_file && (dump_flags & TDF_DETAILS))
2383 fprintf (dump_file, "siv test failed: unimplemented.\n");
2384 *overlaps_a = conflict_fn_not_known ();
2385 *overlaps_b = conflict_fn_not_known ();
2386 *last_conflicts = chrec_dont_know;
2387 dependence_stats.num_siv_unimplemented++;
2390 if (dump_file && (dump_flags & TDF_DETAILS))
2391 fprintf (dump_file, ")\n");
2394 /* Returns false if we can prove that the greatest common divisor of the steps
2395 of CHREC does not divide CST, false otherwise. */
2398 gcd_of_steps_may_divide_p (tree chrec, tree cst)
2400 HOST_WIDE_INT cd = 0, val;
2403 if (!host_integerp (cst, 0))
2405 val = tree_low_cst (cst, 0);
2407 while (TREE_CODE (chrec) == POLYNOMIAL_CHREC)
2409 step = CHREC_RIGHT (chrec);
2410 if (!host_integerp (step, 0))
2412 cd = gcd (cd, tree_low_cst (step, 0));
2413 chrec = CHREC_LEFT (chrec);
2416 return val % cd == 0;
2419 /* Analyze a MIV (Multiple Index Variable) subscript with respect to
2420 LOOP_NEST. *OVERLAPS_A and *OVERLAPS_B are initialized to the
2421 functions that describe the relation between the elements accessed
2422 twice by CHREC_A and CHREC_B. For k >= 0, the following property
2425 CHREC_A (*OVERLAPS_A (k)) = CHREC_B (*OVERLAPS_B (k)). */
2428 analyze_miv_subscript (tree chrec_a,
2430 conflict_function **overlaps_a,
2431 conflict_function **overlaps_b,
2432 tree *last_conflicts,
2433 struct loop *loop_nest)
2435 /* FIXME: This is a MIV subscript, not yet handled.
2436 Example: (A[{1, +, 1}_1] vs. A[{1, +, 1}_2]) that comes from
2439 In the SIV test we had to solve a Diophantine equation with two
2440 variables. In the MIV case we have to solve a Diophantine
2441 equation with 2*n variables (if the subscript uses n IVs).
2444 dependence_stats.num_miv++;
2445 if (dump_file && (dump_flags & TDF_DETAILS))
2446 fprintf (dump_file, "(analyze_miv_subscript \n");
2448 chrec_a = chrec_convert (integer_type_node, chrec_a, NULL_TREE);
2449 chrec_b = chrec_convert (integer_type_node, chrec_b, NULL_TREE);
2450 difference = chrec_fold_minus (integer_type_node, chrec_a, chrec_b);
2452 if (eq_evolutions_p (chrec_a, chrec_b))
2454 /* Access functions are the same: all the elements are accessed
2455 in the same order. */
2456 *overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node));
2457 *overlaps_b = conflict_fn (1, affine_fn_cst (integer_zero_node));
2458 *last_conflicts = estimated_loop_iterations_tree
2459 (get_chrec_loop (chrec_a), true);
2460 dependence_stats.num_miv_dependent++;
2463 else if (evolution_function_is_constant_p (difference)
2464 /* For the moment, the following is verified:
2465 evolution_function_is_affine_multivariate_p (chrec_a,
2467 && !gcd_of_steps_may_divide_p (chrec_a, difference))
2469 /* testsuite/.../ssa-chrec-33.c
2470 {{21, +, 2}_1, +, -2}_2 vs. {{20, +, 2}_1, +, -2}_2
2472 The difference is 1, and all the evolution steps are multiples
2473 of 2, consequently there are no overlapping elements. */
2474 *overlaps_a = conflict_fn_no_dependence ();
2475 *overlaps_b = conflict_fn_no_dependence ();
2476 *last_conflicts = integer_zero_node;
2477 dependence_stats.num_miv_independent++;
2480 else if (evolution_function_is_affine_multivariate_p (chrec_a, loop_nest->num)
2481 && !chrec_contains_symbols (chrec_a)
2482 && evolution_function_is_affine_multivariate_p (chrec_b, loop_nest->num)
2483 && !chrec_contains_symbols (chrec_b))
2485 /* testsuite/.../ssa-chrec-35.c
2486 {0, +, 1}_2 vs. {0, +, 1}_3
2487 the overlapping elements are respectively located at iterations:
2488 {0, +, 1}_x and {0, +, 1}_x,
2489 in other words, we have the equality:
2490 {0, +, 1}_2 ({0, +, 1}_x) = {0, +, 1}_3 ({0, +, 1}_x)
2493 {{0, +, 1}_1, +, 2}_2 ({0, +, 1}_x, {0, +, 1}_y) =
2494 {0, +, 1}_1 ({{0, +, 1}_x, +, 2}_y)
2496 {{0, +, 2}_1, +, 3}_2 ({0, +, 1}_y, {0, +, 1}_x) =
2497 {{0, +, 3}_1, +, 2}_2 ({0, +, 1}_x, {0, +, 1}_y)
2499 analyze_subscript_affine_affine (chrec_a, chrec_b,
2500 overlaps_a, overlaps_b, last_conflicts);
2502 if (CF_NOT_KNOWN_P (*overlaps_a)
2503 || CF_NOT_KNOWN_P (*overlaps_b))
2504 dependence_stats.num_miv_unimplemented++;
2505 else if (CF_NO_DEPENDENCE_P (*overlaps_a)
2506 || CF_NO_DEPENDENCE_P (*overlaps_b))
2507 dependence_stats.num_miv_independent++;
2509 dependence_stats.num_miv_dependent++;
2514 /* When the analysis is too difficult, answer "don't know". */
2515 if (dump_file && (dump_flags & TDF_DETAILS))
2516 fprintf (dump_file, "analyze_miv_subscript test failed: unimplemented.\n");
2518 *overlaps_a = conflict_fn_not_known ();
2519 *overlaps_b = conflict_fn_not_known ();
2520 *last_conflicts = chrec_dont_know;
2521 dependence_stats.num_miv_unimplemented++;
2524 if (dump_file && (dump_flags & TDF_DETAILS))
2525 fprintf (dump_file, ")\n");
2528 /* Determines the iterations for which CHREC_A is equal to CHREC_B in
2529 with respect to LOOP_NEST. OVERLAP_ITERATIONS_A and
2530 OVERLAP_ITERATIONS_B are initialized with two functions that
2531 describe the iterations that contain conflicting elements.
2533 Remark: For an integer k >= 0, the following equality is true:
2535 CHREC_A (OVERLAP_ITERATIONS_A (k)) == CHREC_B (OVERLAP_ITERATIONS_B (k)).
2539 analyze_overlapping_iterations (tree chrec_a,
2541 conflict_function **overlap_iterations_a,
2542 conflict_function **overlap_iterations_b,
2543 tree *last_conflicts, struct loop *loop_nest)
2545 unsigned int lnn = loop_nest->num;
2547 dependence_stats.num_subscript_tests++;
2549 if (dump_file && (dump_flags & TDF_DETAILS))
2551 fprintf (dump_file, "(analyze_overlapping_iterations \n");
2552 fprintf (dump_file, " (chrec_a = ");
2553 print_generic_expr (dump_file, chrec_a, 0);
2554 fprintf (dump_file, ")\n (chrec_b = ");
2555 print_generic_expr (dump_file, chrec_b, 0);
2556 fprintf (dump_file, ")\n");
2559 if (chrec_a == NULL_TREE
2560 || chrec_b == NULL_TREE
2561 || chrec_contains_undetermined (chrec_a)
2562 || chrec_contains_undetermined (chrec_b))
2564 dependence_stats.num_subscript_undetermined++;
2566 *overlap_iterations_a = conflict_fn_not_known ();
2567 *overlap_iterations_b = conflict_fn_not_known ();
2570 /* If they are the same chrec, and are affine, they overlap
2571 on every iteration. */
2572 else if (eq_evolutions_p (chrec_a, chrec_b)
2573 && evolution_function_is_affine_multivariate_p (chrec_a, lnn))
2575 dependence_stats.num_same_subscript_function++;
2576 *overlap_iterations_a = conflict_fn (1, affine_fn_cst (integer_zero_node));
2577 *overlap_iterations_b = conflict_fn (1, affine_fn_cst (integer_zero_node));
2578 *last_conflicts = chrec_dont_know;
2581 /* If they aren't the same, and aren't affine, we can't do anything
2583 else if ((chrec_contains_symbols (chrec_a)
2584 || chrec_contains_symbols (chrec_b))
2585 && (!evolution_function_is_affine_multivariate_p (chrec_a, lnn)
2586 || !evolution_function_is_affine_multivariate_p (chrec_b, lnn)))
2588 dependence_stats.num_subscript_undetermined++;
2589 *overlap_iterations_a = conflict_fn_not_known ();
2590 *overlap_iterations_b = conflict_fn_not_known ();
2593 else if (ziv_subscript_p (chrec_a, chrec_b))
2594 analyze_ziv_subscript (chrec_a, chrec_b,
2595 overlap_iterations_a, overlap_iterations_b,
2598 else if (siv_subscript_p (chrec_a, chrec_b))
2599 analyze_siv_subscript (chrec_a, chrec_b,
2600 overlap_iterations_a, overlap_iterations_b,
2604 analyze_miv_subscript (chrec_a, chrec_b,
2605 overlap_iterations_a, overlap_iterations_b,
2606 last_conflicts, loop_nest);
2608 if (dump_file && (dump_flags & TDF_DETAILS))
2610 fprintf (dump_file, " (overlap_iterations_a = ");
2611 dump_conflict_function (dump_file, *overlap_iterations_a);
2612 fprintf (dump_file, ")\n (overlap_iterations_b = ");
2613 dump_conflict_function (dump_file, *overlap_iterations_b);
2614 fprintf (dump_file, ")\n");
2615 fprintf (dump_file, ")\n");
2619 /* Helper function for uniquely inserting distance vectors. */
2622 save_dist_v (struct data_dependence_relation *ddr, lambda_vector dist_v)
2627 for (i = 0; VEC_iterate (lambda_vector, DDR_DIST_VECTS (ddr), i, v); i++)
2628 if (lambda_vector_equal (v, dist_v, DDR_NB_LOOPS (ddr)))
2631 VEC_safe_push (lambda_vector, heap, DDR_DIST_VECTS (ddr), dist_v);
2634 /* Helper function for uniquely inserting direction vectors. */
2637 save_dir_v (struct data_dependence_relation *ddr, lambda_vector dir_v)
2642 for (i = 0; VEC_iterate (lambda_vector, DDR_DIR_VECTS (ddr), i, v); i++)
2643 if (lambda_vector_equal (v, dir_v, DDR_NB_LOOPS (ddr)))
2646 VEC_safe_push (lambda_vector, heap, DDR_DIR_VECTS (ddr), dir_v);
2649 /* Add a distance of 1 on all the loops outer than INDEX. If we
2650 haven't yet determined a distance for this outer loop, push a new
2651 distance vector composed of the previous distance, and a distance
2652 of 1 for this outer loop. Example:
2660 Saved vectors are of the form (dist_in_1, dist_in_2). First, we
2661 save (0, 1), then we have to save (1, 0). */
2664 add_outer_distances (struct data_dependence_relation *ddr,
2665 lambda_vector dist_v, int index)
2667 /* For each outer loop where init_v is not set, the accesses are
2668 in dependence of distance 1 in the loop. */
2669 while (--index >= 0)
2671 lambda_vector save_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
2672 lambda_vector_copy (dist_v, save_v, DDR_NB_LOOPS (ddr));
2674 save_dist_v (ddr, save_v);
2678 /* Return false when fail to represent the data dependence as a
2679 distance vector. INIT_B is set to true when a component has been
2680 added to the distance vector DIST_V. INDEX_CARRY is then set to
2681 the index in DIST_V that carries the dependence. */
2684 build_classic_dist_vector_1 (struct data_dependence_relation *ddr,
2685 struct data_reference *ddr_a,
2686 struct data_reference *ddr_b,
2687 lambda_vector dist_v, bool *init_b,
2691 lambda_vector init_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
2693 for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++)
2695 tree access_fn_a, access_fn_b;
2696 struct subscript *subscript = DDR_SUBSCRIPT (ddr, i);
2698 if (chrec_contains_undetermined (SUB_DISTANCE (subscript)))
2700 non_affine_dependence_relation (ddr);
2704 access_fn_a = DR_ACCESS_FN (ddr_a, i);
2705 access_fn_b = DR_ACCESS_FN (ddr_b, i);
2707 if (TREE_CODE (access_fn_a) == POLYNOMIAL_CHREC
2708 && TREE_CODE (access_fn_b) == POLYNOMIAL_CHREC)
2711 int index_a = index_in_loop_nest (CHREC_VARIABLE (access_fn_a),
2712 DDR_LOOP_NEST (ddr));
2713 int index_b = index_in_loop_nest (CHREC_VARIABLE (access_fn_b),
2714 DDR_LOOP_NEST (ddr));
2716 /* The dependence is carried by the outermost loop. Example:
2723 In this case, the dependence is carried by loop_1. */
2724 index = index_a < index_b ? index_a : index_b;
2725 *index_carry = MIN (index, *index_carry);
2727 if (chrec_contains_undetermined (SUB_DISTANCE (subscript)))
2729 non_affine_dependence_relation (ddr);
2733 dist = int_cst_value (SUB_DISTANCE (subscript));
2735 /* This is the subscript coupling test. If we have already
2736 recorded a distance for this loop (a distance coming from
2737 another subscript), it should be the same. For example,
2738 in the following code, there is no dependence:
2745 if (init_v[index] != 0 && dist_v[index] != dist)
2747 finalize_ddr_dependent (ddr, chrec_known);
2751 dist_v[index] = dist;
2755 else if (!operand_equal_p (access_fn_a, access_fn_b, 0))
2757 /* This can be for example an affine vs. constant dependence
2758 (T[i] vs. T[3]) that is not an affine dependence and is
2759 not representable as a distance vector. */
2760 non_affine_dependence_relation (ddr);
2768 /* Return true when the DDR contains two data references that have the
2769 same access functions. */
2772 same_access_functions (struct data_dependence_relation *ddr)
2776 for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++)
2777 if (!eq_evolutions_p (DR_ACCESS_FN (DDR_A (ddr), i),
2778 DR_ACCESS_FN (DDR_B (ddr), i)))
2784 /* Return true when the DDR contains only constant access functions. */
2787 constant_access_functions (struct data_dependence_relation *ddr)
2791 for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++)
2792 if (!evolution_function_is_constant_p (DR_ACCESS_FN (DDR_A (ddr), i))
2793 || !evolution_function_is_constant_p (DR_ACCESS_FN (DDR_B (ddr), i)))
2800 /* Helper function for the case where DDR_A and DDR_B are the same
2801 multivariate access function. */
2804 add_multivariate_self_dist (struct data_dependence_relation *ddr, tree c_2)
2807 tree c_1 = CHREC_LEFT (c_2);
2808 tree c_0 = CHREC_LEFT (c_1);
2809 lambda_vector dist_v;
2812 /* Polynomials with more than 2 variables are not handled yet. */
2813 if (TREE_CODE (c_0) != INTEGER_CST)
2815 DDR_ARE_DEPENDENT (ddr) = chrec_dont_know;
2819 x_2 = index_in_loop_nest (CHREC_VARIABLE (c_2), DDR_LOOP_NEST (ddr));
2820 x_1 = index_in_loop_nest (CHREC_VARIABLE (c_1), DDR_LOOP_NEST (ddr));
2822 /* For "{{0, +, 2}_1, +, 3}_2" the distance vector is (3, -2). */
2823 dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
2824 v1 = int_cst_value (CHREC_RIGHT (c_1));
2825 v2 = int_cst_value (CHREC_RIGHT (c_2));
2838 save_dist_v (ddr, dist_v);
2840 add_outer_distances (ddr, dist_v, x_1);
2843 /* Helper function for the case where DDR_A and DDR_B are the same
2844 access functions. */
2847 add_other_self_distances (struct data_dependence_relation *ddr)
2849 lambda_vector dist_v;
2851 int index_carry = DDR_NB_LOOPS (ddr);
2853 for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++)
2855 tree access_fun = DR_ACCESS_FN (DDR_A (ddr), i);
2857 if (TREE_CODE (access_fun) == POLYNOMIAL_CHREC)
2859 if (!evolution_function_is_univariate_p (access_fun))
2861 if (DDR_NUM_SUBSCRIPTS (ddr) != 1)
2863 DDR_ARE_DEPENDENT (ddr) = chrec_dont_know;
2867 add_multivariate_self_dist (ddr, DR_ACCESS_FN (DDR_A (ddr), 0));
2871 index_carry = MIN (index_carry,
2872 index_in_loop_nest (CHREC_VARIABLE (access_fun),
2873 DDR_LOOP_NEST (ddr)));
2877 dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
2878 add_outer_distances (ddr, dist_v, index_carry);
2882 insert_innermost_unit_dist_vector (struct data_dependence_relation *ddr)
2884 lambda_vector dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
2886 dist_v[DDR_INNER_LOOP (ddr)] = 1;
2887 save_dist_v (ddr, dist_v);
2890 /* Adds a unit distance vector to DDR when there is a 0 overlap. This
2891 is the case for example when access functions are the same and
2892 equal to a constant, as in:
2899 in which case the distance vectors are (0) and (1). */
2902 add_distance_for_zero_overlaps (struct data_dependence_relation *ddr)
2906 for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++)
2908 subscript_p sub = DDR_SUBSCRIPT (ddr, i);
2909 conflict_function *ca = SUB_CONFLICTS_IN_A (sub);
2910 conflict_function *cb = SUB_CONFLICTS_IN_B (sub);
2912 for (j = 0; j < ca->n; j++)
2913 if (affine_function_zero_p (ca->fns[j]))
2915 insert_innermost_unit_dist_vector (ddr);
2919 for (j = 0; j < cb->n; j++)
2920 if (affine_function_zero_p (cb->fns[j]))
2922 insert_innermost_unit_dist_vector (ddr);
2928 /* Compute the classic per loop distance vector. DDR is the data
2929 dependence relation to build a vector from. Return false when fail
2930 to represent the data dependence as a distance vector. */
2933 build_classic_dist_vector (struct data_dependence_relation *ddr,
2934 struct loop *loop_nest)
2936 bool init_b = false;
2937 int index_carry = DDR_NB_LOOPS (ddr);
2938 lambda_vector dist_v;
2940 if (DDR_ARE_DEPENDENT (ddr) != NULL_TREE)
2943 if (same_access_functions (ddr))
2945 /* Save the 0 vector. */
2946 dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
2947 save_dist_v (ddr, dist_v);
2949 if (constant_access_functions (ddr))
2950 add_distance_for_zero_overlaps (ddr);
2952 if (DDR_NB_LOOPS (ddr) > 1)
2953 add_other_self_distances (ddr);
2958 dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
2959 if (!build_classic_dist_vector_1 (ddr, DDR_A (ddr), DDR_B (ddr),
2960 dist_v, &init_b, &index_carry))
2963 /* Save the distance vector if we initialized one. */
2966 /* Verify a basic constraint: classic distance vectors should
2967 always be lexicographically positive.
2969 Data references are collected in the order of execution of
2970 the program, thus for the following loop
2972 | for (i = 1; i < 100; i++)
2973 | for (j = 1; j < 100; j++)
2975 | t = T[j+1][i-1]; // A
2976 | T[j][i] = t + 2; // B
2979 references are collected following the direction of the wind:
2980 A then B. The data dependence tests are performed also
2981 following this order, such that we're looking at the distance
2982 separating the elements accessed by A from the elements later
2983 accessed by B. But in this example, the distance returned by
2984 test_dep (A, B) is lexicographically negative (-1, 1), that
2985 means that the access A occurs later than B with respect to
2986 the outer loop, ie. we're actually looking upwind. In this
2987 case we solve test_dep (B, A) looking downwind to the
2988 lexicographically positive solution, that returns the
2989 distance vector (1, -1). */
2990 if (!lambda_vector_lexico_pos (dist_v, DDR_NB_LOOPS (ddr)))
2992 lambda_vector save_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
2993 subscript_dependence_tester_1 (ddr, DDR_B (ddr), DDR_A (ddr),
2995 compute_subscript_distance (ddr);
2996 build_classic_dist_vector_1 (ddr, DDR_B (ddr), DDR_A (ddr),
2997 save_v, &init_b, &index_carry);
2998 save_dist_v (ddr, save_v);
3000 /* In this case there is a dependence forward for all the
3003 | for (k = 1; k < 100; k++)
3004 | for (i = 1; i < 100; i++)
3005 | for (j = 1; j < 100; j++)
3007 | t = T[j+1][i-1]; // A
3008 | T[j][i] = t + 2; // B
3016 if (DDR_NB_LOOPS (ddr) > 1)
3018 add_outer_distances (ddr, save_v, index_carry);
3019 add_outer_distances (ddr, dist_v, index_carry);
3024 lambda_vector save_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
3025 lambda_vector_copy (dist_v, save_v, DDR_NB_LOOPS (ddr));
3026 save_dist_v (ddr, save_v);
3028 if (DDR_NB_LOOPS (ddr) > 1)
3030 lambda_vector opposite_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
3032 subscript_dependence_tester_1 (ddr, DDR_B (ddr), DDR_A (ddr),
3034 compute_subscript_distance (ddr);
3035 build_classic_dist_vector_1 (ddr, DDR_B (ddr), DDR_A (ddr),
3036 opposite_v, &init_b, &index_carry);
3038 add_outer_distances (ddr, dist_v, index_carry);
3039 add_outer_distances (ddr, opposite_v, index_carry);
3045 /* There is a distance of 1 on all the outer loops: Example:
3046 there is a dependence of distance 1 on loop_1 for the array A.
3052 add_outer_distances (ddr, dist_v,
3053 lambda_vector_first_nz (dist_v,
3054 DDR_NB_LOOPS (ddr), 0));
3057 if (dump_file && (dump_flags & TDF_DETAILS))
3061 fprintf (dump_file, "(build_classic_dist_vector\n");
3062 for (i = 0; i < DDR_NUM_DIST_VECTS (ddr); i++)
3064 fprintf (dump_file, " dist_vector = (");
3065 print_lambda_vector (dump_file, DDR_DIST_VECT (ddr, i),
3066 DDR_NB_LOOPS (ddr));
3067 fprintf (dump_file, " )\n");
3069 fprintf (dump_file, ")\n");
3075 /* Return the direction for a given distance.
3076 FIXME: Computing dir this way is suboptimal, since dir can catch
3077 cases that dist is unable to represent. */
3079 static inline enum data_dependence_direction
3080 dir_from_dist (int dist)
3083 return dir_positive;
3085 return dir_negative;
3090 /* Compute the classic per loop direction vector. DDR is the data
3091 dependence relation to build a vector from. */
3094 build_classic_dir_vector (struct data_dependence_relation *ddr)
3097 lambda_vector dist_v;
3099 for (i = 0; VEC_iterate (lambda_vector, DDR_DIST_VECTS (ddr), i, dist_v); i++)
3101 lambda_vector dir_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
3103 for (j = 0; j < DDR_NB_LOOPS (ddr); j++)
3104 dir_v[j] = dir_from_dist (dist_v[j]);
3106 save_dir_v (ddr, dir_v);
3110 /* Helper function. Returns true when there is a dependence between
3111 data references DRA and DRB. */
3114 subscript_dependence_tester_1 (struct data_dependence_relation *ddr,
3115 struct data_reference *dra,
3116 struct data_reference *drb,
3117 struct loop *loop_nest)
3120 tree last_conflicts;
3121 struct subscript *subscript;
3123 for (i = 0; VEC_iterate (subscript_p, DDR_SUBSCRIPTS (ddr), i, subscript);
3126 conflict_function *overlaps_a, *overlaps_b;
3128 analyze_overlapping_iterations (DR_ACCESS_FN (dra, i),
3129 DR_ACCESS_FN (drb, i),
3130 &overlaps_a, &overlaps_b,
3131 &last_conflicts, loop_nest);
3133 if (CF_NOT_KNOWN_P (overlaps_a)
3134 || CF_NOT_KNOWN_P (overlaps_b))
3136 finalize_ddr_dependent (ddr, chrec_dont_know);
3137 dependence_stats.num_dependence_undetermined++;
3138 free_conflict_function (overlaps_a);
3139 free_conflict_function (overlaps_b);
3143 else if (CF_NO_DEPENDENCE_P (overlaps_a)
3144 || CF_NO_DEPENDENCE_P (overlaps_b))
3146 finalize_ddr_dependent (ddr, chrec_known);
3147 dependence_stats.num_dependence_independent++;
3148 free_conflict_function (overlaps_a);
3149 free_conflict_function (overlaps_b);
3155 SUB_CONFLICTS_IN_A (subscript) = overlaps_a;
3156 SUB_CONFLICTS_IN_B (subscript) = overlaps_b;
3157 SUB_LAST_CONFLICT (subscript) = last_conflicts;
3164 /* Computes the conflicting iterations in LOOP_NEST, and initialize DDR. */
3167 subscript_dependence_tester (struct data_dependence_relation *ddr,
3168 struct loop *loop_nest)
3171 if (dump_file && (dump_flags & TDF_DETAILS))
3172 fprintf (dump_file, "(subscript_dependence_tester \n");
3174 if (subscript_dependence_tester_1 (ddr, DDR_A (ddr), DDR_B (ddr), loop_nest))
3175 dependence_stats.num_dependence_dependent++;
3177 compute_subscript_distance (ddr);
3178 if (build_classic_dist_vector (ddr, loop_nest))
3179 build_classic_dir_vector (ddr);
3181 if (dump_file && (dump_flags & TDF_DETAILS))
3182 fprintf (dump_file, ")\n");
3185 /* Returns true when all the access functions of A are affine or
3186 constant with respect to LOOP_NEST. */
3189 access_functions_are_affine_or_constant_p (struct data_reference *a,
3190 struct loop *loop_nest)
3193 VEC(tree,heap) *fns = DR_ACCESS_FNS (a);
3196 for (i = 0; VEC_iterate (tree, fns, i, t); i++)
3197 if (!evolution_function_is_invariant_p (t, loop_nest->num)
3198 && !evolution_function_is_affine_multivariate_p (t, loop_nest->num))
3204 /* Initializes an equation for an OMEGA problem using the information
3205 contained in the ACCESS_FUN. Returns true when the operation
3208 PB is the omega constraint system.
3209 EQ is the number of the equation to be initialized.
3210 OFFSET is used for shifting the variables names in the constraints:
3211 a constrain is composed of 2 * the number of variables surrounding
3212 dependence accesses. OFFSET is set either to 0 for the first n variables,
3213 then it is set to n.
3214 ACCESS_FUN is expected to be an affine chrec. */
3217 init_omega_eq_with_af (omega_pb pb, unsigned eq,
3218 unsigned int offset, tree access_fun,
3219 struct data_dependence_relation *ddr)
3221 switch (TREE_CODE (access_fun))
3223 case POLYNOMIAL_CHREC:
3225 tree left = CHREC_LEFT (access_fun);
3226 tree right = CHREC_RIGHT (access_fun);
3227 int var = CHREC_VARIABLE (access_fun);
3230 if (TREE_CODE (right) != INTEGER_CST)
3233 var_idx = index_in_loop_nest (var, DDR_LOOP_NEST (ddr));
3234 pb->eqs[eq].coef[offset + var_idx + 1] = int_cst_value (right);
3236 /* Compute the innermost loop index. */
3237 DDR_INNER_LOOP (ddr) = MAX (DDR_INNER_LOOP (ddr), var_idx);
3240 pb->eqs[eq].coef[var_idx + DDR_NB_LOOPS (ddr) + 1]
3241 += int_cst_value (right);
3243 switch (TREE_CODE (left))
3245 case POLYNOMIAL_CHREC:
3246 return init_omega_eq_with_af (pb, eq, offset, left, ddr);
3249 pb->eqs[eq].coef[0] += int_cst_value (left);
3258 pb->eqs[eq].coef[0] += int_cst_value (access_fun);
3266 /* As explained in the comments preceding init_omega_for_ddr, we have
3267 to set up a system for each loop level, setting outer loops
3268 variation to zero, and current loop variation to positive or zero.
3269 Save each lexico positive distance vector. */
3272 omega_extract_distance_vectors (omega_pb pb,
3273 struct data_dependence_relation *ddr)
3277 struct loop *loopi, *loopj;
3278 enum omega_result res;
3280 /* Set a new problem for each loop in the nest. The basis is the
3281 problem that we have initialized until now. On top of this we
3282 add new constraints. */
3283 for (i = 0; i <= DDR_INNER_LOOP (ddr)
3284 && VEC_iterate (loop_p, DDR_LOOP_NEST (ddr), i, loopi); i++)
3287 omega_pb copy = omega_alloc_problem (2 * DDR_NB_LOOPS (ddr),
3288 DDR_NB_LOOPS (ddr));
3290 omega_copy_problem (copy, pb);
3292 /* For all the outer loops "loop_j", add "dj = 0". */
3294 j < i && VEC_iterate (loop_p, DDR_LOOP_NEST (ddr), j, loopj); j++)
3296 eq = omega_add_zero_eq (copy, omega_black);
3297 copy->eqs[eq].coef[j + 1] = 1;
3300 /* For "loop_i", add "0 <= di". */
3301 geq = omega_add_zero_geq (copy, omega_black);
3302 copy->geqs[geq].coef[i + 1] = 1;
3304 /* Reduce the constraint system, and test that the current
3305 problem is feasible. */
3306 res = omega_simplify_problem (copy);
3307 if (res == omega_false
3308 || res == omega_unknown
3309 || copy->num_geqs > (int) DDR_NB_LOOPS (ddr))
3312 for (eq = 0; eq < copy->num_subs; eq++)
3313 if (copy->subs[eq].key == (int) i + 1)
3315 dist = copy->subs[eq].coef[0];
3321 /* Reinitialize problem... */
3322 omega_copy_problem (copy, pb);
3324 j < i && VEC_iterate (loop_p, DDR_LOOP_NEST (ddr), j, loopj); j++)
3326 eq = omega_add_zero_eq (copy, omega_black);
3327 copy->eqs[eq].coef[j + 1] = 1;
3330 /* ..., but this time "di = 1". */
3331 eq = omega_add_zero_eq (copy, omega_black);
3332 copy->eqs[eq].coef[i + 1] = 1;
3333 copy->eqs[eq].coef[0] = -1;
3335 res = omega_simplify_problem (copy);
3336 if (res == omega_false
3337 || res == omega_unknown
3338 || copy->num_geqs > (int) DDR_NB_LOOPS (ddr))
3341 for (eq = 0; eq < copy->num_subs; eq++)
3342 if (copy->subs[eq].key == (int) i + 1)
3344 dist = copy->subs[eq].coef[0];
3350 /* Save the lexicographically positive distance vector. */
3353 lambda_vector dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
3354 lambda_vector dir_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
3358 for (eq = 0; eq < copy->num_subs; eq++)
3359 if (copy->subs[eq].key > 0)
3361 dist = copy->subs[eq].coef[0];
3362 dist_v[copy->subs[eq].key - 1] = dist;
3365 for (j = 0; j < DDR_NB_LOOPS (ddr); j++)
3366 dir_v[j] = dir_from_dist (dist_v[j]);
3368 save_dist_v (ddr, dist_v);
3369 save_dir_v (ddr, dir_v);
3373 omega_free_problem (copy);
3377 /* This is called for each subscript of a tuple of data references:
3378 insert an equality for representing the conflicts. */
3381 omega_setup_subscript (tree access_fun_a, tree access_fun_b,
3382 struct data_dependence_relation *ddr,
3383 omega_pb pb, bool *maybe_dependent)
3386 tree fun_a = chrec_convert (integer_type_node, access_fun_a, NULL_TREE);
3387 tree fun_b = chrec_convert (integer_type_node, access_fun_b, NULL_TREE);
3388 tree difference = chrec_fold_minus (integer_type_node, fun_a, fun_b);
3390 /* When the fun_a - fun_b is not constant, the dependence is not
3391 captured by the classic distance vector representation. */
3392 if (TREE_CODE (difference) != INTEGER_CST)
3396 if (ziv_subscript_p (fun_a, fun_b) && !integer_zerop (difference))
3398 /* There is no dependence. */
3399 *maybe_dependent = false;
3403 fun_b = chrec_fold_multiply (integer_type_node, fun_b,
3404 integer_minus_one_node);
3406 eq = omega_add_zero_eq (pb, omega_black);
3407 if (!init_omega_eq_with_af (pb, eq, DDR_NB_LOOPS (ddr), fun_a, ddr)
3408 || !init_omega_eq_with_af (pb, eq, 0, fun_b, ddr))
3409 /* There is probably a dependence, but the system of
3410 constraints cannot be built: answer "don't know". */
3414 if (DDR_NB_LOOPS (ddr) != 0 && pb->eqs[eq].coef[0]
3415 && !int_divides_p (lambda_vector_gcd
3416 ((lambda_vector) &(pb->eqs[eq].coef[1]),
3417 2 * DDR_NB_LOOPS (ddr)),
3418 pb->eqs[eq].coef[0]))
3420 /* There is no dependence. */
3421 *maybe_dependent = false;
3428 /* Helper function, same as init_omega_for_ddr but specialized for
3429 data references A and B. */
3432 init_omega_for_ddr_1 (struct data_reference *dra, struct data_reference *drb,
3433 struct data_dependence_relation *ddr,
3434 omega_pb pb, bool *maybe_dependent)
3439 unsigned nb_loops = DDR_NB_LOOPS (ddr);
3441 /* Insert an equality per subscript. */
3442 for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++)
3444 if (!omega_setup_subscript (DR_ACCESS_FN (dra, i), DR_ACCESS_FN (drb, i),
3445 ddr, pb, maybe_dependent))
3447 else if (*maybe_dependent == false)
3449 /* There is no dependence. */
3450 DDR_ARE_DEPENDENT (ddr) = chrec_known;
3455 /* Insert inequalities: constraints corresponding to the iteration
3456 domain, i.e. the loops surrounding the references "loop_x" and
3457 the distance variables "dx". The layout of the OMEGA
3458 representation is as follows:
3459 - coef[0] is the constant
3460 - coef[1..nb_loops] are the protected variables that will not be
3461 removed by the solver: the "dx"
3462 - coef[nb_loops + 1, 2*nb_loops] are the loop variables: "loop_x".
3464 for (i = 0; i <= DDR_INNER_LOOP (ddr)
3465 && VEC_iterate (loop_p, DDR_LOOP_NEST (ddr), i, loopi); i++)
3467 HOST_WIDE_INT nbi = estimated_loop_iterations_int (loopi, false);
3470 ineq = omega_add_zero_geq (pb, omega_black);
3471 pb->geqs[ineq].coef[i + nb_loops + 1] = 1;
3473 /* 0 <= loop_x + dx */
3474 ineq = omega_add_zero_geq (pb, omega_black);
3475 pb->geqs[ineq].coef[i + nb_loops + 1] = 1;
3476 pb->geqs[ineq].coef[i + 1] = 1;
3480 /* loop_x <= nb_iters */
3481 ineq = omega_add_zero_geq (pb, omega_black);
3482 pb->geqs[ineq].coef[i + nb_loops + 1] = -1;
3483 pb->geqs[ineq].coef[0] = nbi;
3485 /* loop_x + dx <= nb_iters */
3486 ineq = omega_add_zero_geq (pb, omega_black);
3487 pb->geqs[ineq].coef[i + nb_loops + 1] = -1;
3488 pb->geqs[ineq].coef[i + 1] = -1;
3489 pb->geqs[ineq].coef[0] = nbi;
3491 /* A step "dx" bigger than nb_iters is not feasible, so
3492 add "0 <= nb_iters + dx", */
3493 ineq = omega_add_zero_geq (pb, omega_black);
3494 pb->geqs[ineq].coef[i + 1] = 1;
3495 pb->geqs[ineq].coef[0] = nbi;
3496 /* and "dx <= nb_iters". */
3497 ineq = omega_add_zero_geq (pb, omega_black);
3498 pb->geqs[ineq].coef[i + 1] = -1;
3499 pb->geqs[ineq].coef[0] = nbi;
3503 omega_extract_distance_vectors (pb, ddr);
3508 /* Sets up the Omega dependence problem for the data dependence
3509 relation DDR. Returns false when the constraint system cannot be
3510 built, ie. when the test answers "don't know". Returns true
3511 otherwise, and when independence has been proved (using one of the
3512 trivial dependence test), set MAYBE_DEPENDENT to false, otherwise
3513 set MAYBE_DEPENDENT to true.
3515 Example: for setting up the dependence system corresponding to the
3516 conflicting accesses
3521 | ... A[2*j, 2*(i + j)]
3525 the following constraints come from the iteration domain:
3532 where di, dj are the distance variables. The constraints
3533 representing the conflicting elements are:
3536 i + 1 = 2 * (i + di + j + dj)
3538 For asking that the resulting distance vector (di, dj) be
3539 lexicographically positive, we insert the constraint "di >= 0". If
3540 "di = 0" in the solution, we fix that component to zero, and we
3541 look at the inner loops: we set a new problem where all the outer
3542 loop distances are zero, and fix this inner component to be
3543 positive. When one of the components is positive, we save that
3544 distance, and set a new problem where the distance on this loop is
3545 zero, searching for other distances in the inner loops. Here is
3546 the classic example that illustrates that we have to set for each
3547 inner loop a new problem:
3555 we have to save two distances (1, 0) and (0, 1).
3557 Given two array references, refA and refB, we have to set the
3558 dependence problem twice, refA vs. refB and refB vs. refA, and we
3559 cannot do a single test, as refB might occur before refA in the
3560 inner loops, and the contrary when considering outer loops: ex.
3565 | T[{1,+,1}_2][{1,+,1}_1] // refA
3566 | T[{2,+,1}_2][{0,+,1}_1] // refB
3571 refB touches the elements in T before refA, and thus for the same
3572 loop_0 refB precedes refA: ie. the distance vector (0, 1, -1)
3573 but for successive loop_0 iterations, we have (1, -1, 1)
3575 The Omega solver expects the distance variables ("di" in the
3576 previous example) to come first in the constraint system (as
3577 variables to be protected, or "safe" variables), the constraint
3578 system is built using the following layout:
3580 "cst | distance vars | index vars".
3584 init_omega_for_ddr (struct data_dependence_relation *ddr,
3585 bool *maybe_dependent)
3590 *maybe_dependent = true;
3592 if (same_access_functions (ddr))
3595 lambda_vector dir_v;
3597 /* Save the 0 vector. */
3598 save_dist_v (ddr, lambda_vector_new (DDR_NB_LOOPS (ddr)));
3599 dir_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
3600 for (j = 0; j < DDR_NB_LOOPS (ddr); j++)
3601 dir_v[j] = dir_equal;
3602 save_dir_v (ddr, dir_v);
3604 /* Save the dependences carried by outer loops. */
3605 pb = omega_alloc_problem (2 * DDR_NB_LOOPS (ddr), DDR_NB_LOOPS (ddr));
3606 res = init_omega_for_ddr_1 (DDR_A (ddr), DDR_B (ddr), ddr, pb,
3608 omega_free_problem (pb);
3612 /* Omega expects the protected variables (those that have to be kept
3613 after elimination) to appear first in the constraint system.
3614 These variables are the distance variables. In the following
3615 initialization we declare NB_LOOPS safe variables, and the total
3616 number of variables for the constraint system is 2*NB_LOOPS. */
3617 pb = omega_alloc_problem (2 * DDR_NB_LOOPS (ddr), DDR_NB_LOOPS (ddr));
3618 res = init_omega_for_ddr_1 (DDR_A (ddr), DDR_B (ddr), ddr, pb,
3620 omega_free_problem (pb);
3622 /* Stop computation if not decidable, or no dependence. */
3623 if (res == false || *maybe_dependent == false)
3626 pb = omega_alloc_problem (2 * DDR_NB_LOOPS (ddr), DDR_NB_LOOPS (ddr));
3627 res = init_omega_for_ddr_1 (DDR_B (ddr), DDR_A (ddr), ddr, pb,
3629 omega_free_problem (pb);
3634 /* Return true when DDR contains the same information as that stored
3635 in DIR_VECTS and in DIST_VECTS, return false otherwise. */
3638 ddr_consistent_p (FILE *file,
3639 struct data_dependence_relation *ddr,
3640 VEC (lambda_vector, heap) *dist_vects,
3641 VEC (lambda_vector, heap) *dir_vects)
3645 /* If dump_file is set, output there. */
3646 if (dump_file && (dump_flags & TDF_DETAILS))
3649 if (VEC_length (lambda_vector, dist_vects) != DDR_NUM_DIST_VECTS (ddr))
3651 lambda_vector b_dist_v;
3652 fprintf (file, "\n(Number of distance vectors differ: Banerjee has %d, Omega has %d.\n",
3653 VEC_length (lambda_vector, dist_vects),
3654 DDR_NUM_DIST_VECTS (ddr));
3656 fprintf (file, "Banerjee dist vectors:\n");
3657 for (i = 0; VEC_iterate (lambda_vector, dist_vects, i, b_dist_v); i++)
3658 print_lambda_vector (file, b_dist_v, DDR_NB_LOOPS (ddr));
3660 fprintf (file, "Omega dist vectors:\n");
3661 for (i = 0; i < DDR_NUM_DIST_VECTS (ddr); i++)
3662 print_lambda_vector (file, DDR_DIST_VECT (ddr, i), DDR_NB_LOOPS (ddr));
3664 fprintf (file, "data dependence relation:\n");
3665 dump_data_dependence_relation (file, ddr);
3667 fprintf (file, ")\n");
3671 if (VEC_length (lambda_vector, dir_vects) != DDR_NUM_DIR_VECTS (ddr))
3673 fprintf (file, "\n(Number of direction vectors differ: Banerjee has %d, Omega has %d.)\n",
3674 VEC_length (lambda_vector, dir_vects),
3675 DDR_NUM_DIR_VECTS (ddr));
3679 for (i = 0; i < DDR_NUM_DIST_VECTS (ddr); i++)
3681 lambda_vector a_dist_v;
3682 lambda_vector b_dist_v = DDR_DIST_VECT (ddr, i);
3684 /* Distance vectors are not ordered in the same way in the DDR
3685 and in the DIST_VECTS: search for a matching vector. */
3686 for (j = 0; VEC_iterate (lambda_vector, dist_vects, j, a_dist_v); j++)
3687 if (lambda_vector_equal (a_dist_v, b_dist_v, DDR_NB_LOOPS (ddr)))
3690 if (j == VEC_length (lambda_vector, dist_vects))
3692 fprintf (file, "\n(Dist vectors from the first dependence analyzer:\n");
3693 print_dist_vectors (file, dist_vects, DDR_NB_LOOPS (ddr));
3694 fprintf (file, "not found in Omega dist vectors:\n");
3695 print_dist_vectors (file, DDR_DIST_VECTS (ddr), DDR_NB_LOOPS (ddr));
3696 fprintf (file, "data dependence relation:\n");
3697 dump_data_dependence_relation (file, ddr);
3698 fprintf (file, ")\n");
3702 for (i = 0; i < DDR_NUM_DIR_VECTS (ddr); i++)
3704 lambda_vector a_dir_v;
3705 lambda_vector b_dir_v = DDR_DIR_VECT (ddr, i);
3707 /* Direction vectors are not ordered in the same way in the DDR
3708 and in the DIR_VECTS: search for a matching vector. */
3709 for (j = 0; VEC_iterate (lambda_vector, dir_vects, j, a_dir_v); j++)
3710 if (lambda_vector_equal (a_dir_v, b_dir_v, DDR_NB_LOOPS (ddr)))
3713 if (j == VEC_length (lambda_vector, dist_vects))
3715 fprintf (file, "\n(Dir vectors from the first dependence analyzer:\n");
3716 print_dir_vectors (file, dir_vects, DDR_NB_LOOPS (ddr));
3717 fprintf (file, "not found in Omega dir vectors:\n");
3718 print_dir_vectors (file, DDR_DIR_VECTS (ddr), DDR_NB_LOOPS (ddr));
3719 fprintf (file, "data dependence relation:\n");
3720 dump_data_dependence_relation (file, ddr);
3721 fprintf (file, ")\n");
3728 /* This computes the affine dependence relation between A and B with
3729 respect to LOOP_NEST. CHREC_KNOWN is used for representing the
3730 independence between two accesses, while CHREC_DONT_KNOW is used
3731 for representing the unknown relation.
3733 Note that it is possible to stop the computation of the dependence
3734 relation the first time we detect a CHREC_KNOWN element for a given
3738 compute_affine_dependence (struct data_dependence_relation *ddr,
3739 struct loop *loop_nest)
3741 struct data_reference *dra = DDR_A (ddr);
3742 struct data_reference *drb = DDR_B (ddr);
3744 if (dump_file && (dump_flags & TDF_DETAILS))
3746 fprintf (dump_file, "(compute_affine_dependence\n");
3747 fprintf (dump_file, " (stmt_a = \n");
3748 print_generic_expr (dump_file, DR_STMT (dra), 0);
3749 fprintf (dump_file, ")\n (stmt_b = \n");
3750 print_generic_expr (dump_file, DR_STMT (drb), 0);
3751 fprintf (dump_file, ")\n");
3754 /* Analyze only when the dependence relation is not yet known. */
3755 if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE)
3757 dependence_stats.num_dependence_tests++;
3759 if (access_functions_are_affine_or_constant_p (dra, loop_nest)
3760 && access_functions_are_affine_or_constant_p (drb, loop_nest))
3762 if (flag_check_data_deps)
3764 /* Compute the dependences using the first algorithm. */
3765 subscript_dependence_tester (ddr, loop_nest);
3767 if (dump_file && (dump_flags & TDF_DETAILS))
3769 fprintf (dump_file, "\n\nBanerjee Analyzer\n");
3770 dump_data_dependence_relation (dump_file, ddr);
3773 if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE)
3775 bool maybe_dependent;
3776 VEC (lambda_vector, heap) *dir_vects, *dist_vects;
3778 /* Save the result of the first DD analyzer. */
3779 dist_vects = DDR_DIST_VECTS (ddr);
3780 dir_vects = DDR_DIR_VECTS (ddr);
3782 /* Reset the information. */
3783 DDR_DIST_VECTS (ddr) = NULL;
3784 DDR_DIR_VECTS (ddr) = NULL;
3786 /* Compute the same information using Omega. */
3787 if (!init_omega_for_ddr (ddr, &maybe_dependent))
3788 goto csys_dont_know;
3790 if (dump_file && (dump_flags & TDF_DETAILS))
3792 fprintf (dump_file, "Omega Analyzer\n");
3793 dump_data_dependence_relation (dump_file, ddr);
3796 /* Check that we get the same information. */
3797 if (maybe_dependent)
3798 gcc_assert (ddr_consistent_p (stderr, ddr, dist_vects,
3803 subscript_dependence_tester (ddr, loop_nest);
3806 /* As a last case, if the dependence cannot be determined, or if
3807 the dependence is considered too difficult to determine, answer
3812 dependence_stats.num_dependence_undetermined++;
3814 if (dump_file && (dump_flags & TDF_DETAILS))
3816 fprintf (dump_file, "Data ref a:\n");
3817 dump_data_reference (dump_file, dra);
3818 fprintf (dump_file, "Data ref b:\n");
3819 dump_data_reference (dump_file, drb);
3820 fprintf (dump_file, "affine dependence test not usable: access function not affine or constant.\n");
3822 finalize_ddr_dependent (ddr, chrec_dont_know);
3826 if (dump_file && (dump_flags & TDF_DETAILS))
3827 fprintf (dump_file, ")\n");
3830 /* This computes the dependence relation for the same data
3831 reference into DDR. */
3834 compute_self_dependence (struct data_dependence_relation *ddr)
3837 struct subscript *subscript;
3839 if (DDR_ARE_DEPENDENT (ddr) != NULL_TREE)
3842 for (i = 0; VEC_iterate (subscript_p, DDR_SUBSCRIPTS (ddr), i, subscript);
3845 /* The accessed index overlaps for each iteration. */
3846 SUB_CONFLICTS_IN_A (subscript)
3847 = conflict_fn (1, affine_fn_cst (integer_zero_node));
3848 SUB_CONFLICTS_IN_B (subscript)
3849 = conflict_fn (1, affine_fn_cst (integer_zero_node));
3850 SUB_LAST_CONFLICT (subscript) = chrec_dont_know;
3853 /* The distance vector is the zero vector. */
3854 save_dist_v (ddr, lambda_vector_new (DDR_NB_LOOPS (ddr)));
3855 save_dir_v (ddr, lambda_vector_new (DDR_NB_LOOPS (ddr)));
3858 /* Compute in DEPENDENCE_RELATIONS the data dependence graph for all
3859 the data references in DATAREFS, in the LOOP_NEST. When
3860 COMPUTE_SELF_AND_RR is FALSE, don't compute read-read and self
3864 compute_all_dependences (VEC (data_reference_p, heap) *datarefs,
3865 VEC (ddr_p, heap) **dependence_relations,
3866 VEC (loop_p, heap) *loop_nest,
3867 bool compute_self_and_rr)
3869 struct data_dependence_relation *ddr;
3870 struct data_reference *a, *b;
3873 for (i = 0; VEC_iterate (data_reference_p, datarefs, i, a); i++)
3874 for (j = i + 1; VEC_iterate (data_reference_p, datarefs, j, b); j++)
3875 if (!DR_IS_READ (a) || !DR_IS_READ (b) || compute_self_and_rr)
3877 ddr = initialize_data_dependence_relation (a, b, loop_nest);
3878 VEC_safe_push (ddr_p, heap, *dependence_relations, ddr);
3879 compute_affine_dependence (ddr, VEC_index (loop_p, loop_nest, 0));
3882 if (compute_self_and_rr)
3883 for (i = 0; VEC_iterate (data_reference_p, datarefs, i, a); i++)
3885 ddr = initialize_data_dependence_relation (a, a, loop_nest);
3886 VEC_safe_push (ddr_p, heap, *dependence_relations, ddr);
3887 compute_self_dependence (ddr);
3891 /* Stores the locations of memory references in STMT to REFERENCES. Returns
3892 true if STMT clobbers memory, false otherwise. */
3895 get_references_in_stmt (tree stmt, VEC (data_ref_loc, heap) **references)
3897 bool clobbers_memory = false;
3899 tree *op0, *op1, call;
3903 /* ASM_EXPR and CALL_EXPR may embed arbitrary side effects.
3904 Calls have side-effects, except those to const or pure
3906 call = get_call_expr_in (stmt);
3908 && !(call_expr_flags (call) & (ECF_CONST | ECF_PURE)))
3909 || (TREE_CODE (stmt) == ASM_EXPR
3910 && ASM_VOLATILE_P (stmt)))
3911 clobbers_memory = true;
3913 if (ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3914 return clobbers_memory;
3916 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
3918 op0 = &GIMPLE_STMT_OPERAND (stmt, 0);
3919 op1 = &GIMPLE_STMT_OPERAND (stmt, 1);
3922 || REFERENCE_CLASS_P (*op1))
3924 ref = VEC_safe_push (data_ref_loc, heap, *references, NULL);
3926 ref->is_read = true;
3930 || REFERENCE_CLASS_P (*op0))
3932 ref = VEC_safe_push (data_ref_loc, heap, *references, NULL);
3934 ref->is_read = false;
3940 unsigned i, n = call_expr_nargs (call);
3942 for (i = 0; i < n; i++)
3944 op0 = &CALL_EXPR_ARG (call, i);
3947 || REFERENCE_CLASS_P (*op0))
3949 ref = VEC_safe_push (data_ref_loc, heap, *references, NULL);
3951 ref->is_read = true;
3956 return clobbers_memory;
3959 /* Stores the data references in STMT to DATAREFS. If there is an unanalyzable
3960 reference, returns false, otherwise returns true. NEST is the outermost
3961 loop of the loop nest in that the references should be analyzed. */
3964 find_data_references_in_stmt (struct loop *nest, tree stmt,
3965 VEC (data_reference_p, heap) **datarefs)
3968 VEC (data_ref_loc, heap) *references;
3971 data_reference_p dr;
3973 if (get_references_in_stmt (stmt, &references))
3975 VEC_free (data_ref_loc, heap, references);
3979 for (i = 0; VEC_iterate (data_ref_loc, references, i, ref); i++)
3981 dr = create_data_ref (nest, *ref->pos, stmt, ref->is_read);
3982 gcc_assert (dr != NULL);
3984 /* FIXME -- data dependence analysis does not work correctly for objects with
3985 invariant addresses. Let us fail here until the problem is fixed. */
3986 if (dr_address_invariant_p (dr))
3989 if (dump_file && (dump_flags & TDF_DETAILS))
3990 fprintf (dump_file, "\tFAILED as dr address is invariant\n");
3995 VEC_safe_push (data_reference_p, heap, *datarefs, dr);
3997 VEC_free (data_ref_loc, heap, references);
4001 /* Search the data references in LOOP, and record the information into
4002 DATAREFS. Returns chrec_dont_know when failing to analyze a
4003 difficult case, returns NULL_TREE otherwise.
4005 TODO: This function should be made smarter so that it can handle address
4006 arithmetic as if they were array accesses, etc. */
4009 find_data_references_in_loop (struct loop *loop,
4010 VEC (data_reference_p, heap) **datarefs)
4012 basic_block bb, *bbs;
4014 block_stmt_iterator bsi;
4016 bbs = get_loop_body_in_dom_order (loop);
4018 for (i = 0; i < loop->num_nodes; i++)
4022 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4024 tree stmt = bsi_stmt (bsi);
4026 if (!find_data_references_in_stmt (loop, stmt, datarefs))
4028 struct data_reference *res;
4029 res = XCNEW (struct data_reference);
4030 VEC_safe_push (data_reference_p, heap, *datarefs, res);
4033 return chrec_dont_know;
4042 /* Recursive helper function. */
4045 find_loop_nest_1 (struct loop *loop, VEC (loop_p, heap) **loop_nest)
4047 /* Inner loops of the nest should not contain siblings. Example:
4048 when there are two consecutive loops,
4059 the dependence relation cannot be captured by the distance
4064 VEC_safe_push (loop_p, heap, *loop_nest, loop);
4066 return find_loop_nest_1 (loop->inner, loop_nest);
4070 /* Return false when the LOOP is not well nested. Otherwise return
4071 true and insert in LOOP_NEST the loops of the nest. LOOP_NEST will
4072 contain the loops from the outermost to the innermost, as they will
4073 appear in the classic distance vector. */
4076 find_loop_nest (struct loop *loop, VEC (loop_p, heap) **loop_nest)
4078 VEC_safe_push (loop_p, heap, *loop_nest, loop);
4080 return find_loop_nest_1 (loop->inner, loop_nest);
4084 /* Given a loop nest LOOP, the following vectors are returned:
4085 DATAREFS is initialized to all the array elements contained in this loop,
4086 DEPENDENCE_RELATIONS contains the relations between the data references.
4087 Compute read-read and self relations if
4088 COMPUTE_SELF_AND_READ_READ_DEPENDENCES is TRUE. */
4091 compute_data_dependences_for_loop (struct loop *loop,
4092 bool compute_self_and_read_read_dependences,
4093 VEC (data_reference_p, heap) **datarefs,
4094 VEC (ddr_p, heap) **dependence_relations)
4096 VEC (loop_p, heap) *vloops = VEC_alloc (loop_p, heap, 3);
4098 memset (&dependence_stats, 0, sizeof (dependence_stats));
4100 /* If the loop nest is not well formed, or one of the data references
4101 is not computable, give up without spending time to compute other
4104 || !find_loop_nest (loop, &vloops)
4105 || find_data_references_in_loop (loop, datarefs) == chrec_dont_know)
4107 struct data_dependence_relation *ddr;
4109 /* Insert a single relation into dependence_relations:
4111 ddr = initialize_data_dependence_relation (NULL, NULL, vloops);
4112 VEC_safe_push (ddr_p, heap, *dependence_relations, ddr);
4115 compute_all_dependences (*datarefs, dependence_relations, vloops,
4116 compute_self_and_read_read_dependences);
4118 if (dump_file && (dump_flags & TDF_STATS))
4120 fprintf (dump_file, "Dependence tester statistics:\n");
4122 fprintf (dump_file, "Number of dependence tests: %d\n",
4123 dependence_stats.num_dependence_tests);
4124 fprintf (dump_file, "Number of dependence tests classified dependent: %d\n",
4125 dependence_stats.num_dependence_dependent);
4126 fprintf (dump_file, "Number of dependence tests classified independent: %d\n",
4127 dependence_stats.num_dependence_independent);
4128 fprintf (dump_file, "Number of undetermined dependence tests: %d\n",
4129 dependence_stats.num_dependence_undetermined);
4131 fprintf (dump_file, "Number of subscript tests: %d\n",
4132 dependence_stats.num_subscript_tests);
4133 fprintf (dump_file, "Number of undetermined subscript tests: %d\n",
4134 dependence_stats.num_subscript_undetermined);
4135 fprintf (dump_file, "Number of same subscript function: %d\n",
4136 dependence_stats.num_same_subscript_function);
4138 fprintf (dump_file, "Number of ziv tests: %d\n",
4139 dependence_stats.num_ziv);
4140 fprintf (dump_file, "Number of ziv tests returning dependent: %d\n",
4141 dependence_stats.num_ziv_dependent);
4142 fprintf (dump_file, "Number of ziv tests returning independent: %d\n",
4143 dependence_stats.num_ziv_independent);
4144 fprintf (dump_file, "Number of ziv tests unimplemented: %d\n",
4145 dependence_stats.num_ziv_unimplemented);
4147 fprintf (dump_file, "Number of siv tests: %d\n",
4148 dependence_stats.num_siv);
4149 fprintf (dump_file, "Number of siv tests returning dependent: %d\n",
4150 dependence_stats.num_siv_dependent);
4151 fprintf (dump_file, "Number of siv tests returning independent: %d\n",
4152 dependence_stats.num_siv_independent);
4153 fprintf (dump_file, "Number of siv tests unimplemented: %d\n",
4154 dependence_stats.num_siv_unimplemented);
4156 fprintf (dump_file, "Number of miv tests: %d\n",
4157 dependence_stats.num_miv);
4158 fprintf (dump_file, "Number of miv tests returning dependent: %d\n",
4159 dependence_stats.num_miv_dependent);
4160 fprintf (dump_file, "Number of miv tests returning independent: %d\n",
4161 dependence_stats.num_miv_independent);
4162 fprintf (dump_file, "Number of miv tests unimplemented: %d\n",
4163 dependence_stats.num_miv_unimplemented);
4167 /* Entry point (for testing only). Analyze all the data references
4168 and the dependence relations in LOOP.
4170 The data references are computed first.
4172 A relation on these nodes is represented by a complete graph. Some
4173 of the relations could be of no interest, thus the relations can be
4176 In the following function we compute all the relations. This is
4177 just a first implementation that is here for:
4178 - for showing how to ask for the dependence relations,
4179 - for the debugging the whole dependence graph,
4180 - for the dejagnu testcases and maintenance.
4182 It is possible to ask only for a part of the graph, avoiding to
4183 compute the whole dependence graph. The computed dependences are
4184 stored in a knowledge base (KB) such that later queries don't
4185 recompute the same information. The implementation of this KB is
4186 transparent to the optimizer, and thus the KB can be changed with a
4187 more efficient implementation, or the KB could be disabled. */
4189 analyze_all_data_dependences (struct loop *loop)
4192 int nb_data_refs = 10;
4193 VEC (data_reference_p, heap) *datarefs =
4194 VEC_alloc (data_reference_p, heap, nb_data_refs);
4195 VEC (ddr_p, heap) *dependence_relations =
4196 VEC_alloc (ddr_p, heap, nb_data_refs * nb_data_refs);
4198 /* Compute DDs on the whole function. */
4199 compute_data_dependences_for_loop (loop, false, &datarefs,
4200 &dependence_relations);
4204 dump_data_dependence_relations (dump_file, dependence_relations);
4205 fprintf (dump_file, "\n\n");
4207 if (dump_flags & TDF_DETAILS)
4208 dump_dist_dir_vectors (dump_file, dependence_relations);
4210 if (dump_flags & TDF_STATS)
4212 unsigned nb_top_relations = 0;
4213 unsigned nb_bot_relations = 0;
4214 unsigned nb_basename_differ = 0;
4215 unsigned nb_chrec_relations = 0;
4216 struct data_dependence_relation *ddr;
4218 for (i = 0; VEC_iterate (ddr_p, dependence_relations, i, ddr); i++)
4220 if (chrec_contains_undetermined (DDR_ARE_DEPENDENT (ddr)))
4223 else if (DDR_ARE_DEPENDENT (ddr) == chrec_known)
4225 struct data_reference *a = DDR_A (ddr);
4226 struct data_reference *b = DDR_B (ddr);
4228 if (!bitmap_intersect_p (DR_VOPS (a), DR_VOPS (b)))
4229 nb_basename_differ++;
4235 nb_chrec_relations++;
4238 gather_stats_on_scev_database ();
4242 free_dependence_relations (dependence_relations);
4243 free_data_refs (datarefs);
4246 /* Computes all the data dependences and check that the results of
4247 several analyzers are the same. */
4250 tree_check_data_deps (void)
4253 struct loop *loop_nest;
4255 FOR_EACH_LOOP (li, loop_nest, 0)
4256 analyze_all_data_dependences (loop_nest);
4259 /* Free the memory used by a data dependence relation DDR. */
4262 free_dependence_relation (struct data_dependence_relation *ddr)
4267 if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE && DDR_SUBSCRIPTS (ddr))
4268 free_subscripts (DDR_SUBSCRIPTS (ddr));
4273 /* Free the memory used by the data dependence relations from
4274 DEPENDENCE_RELATIONS. */
4277 free_dependence_relations (VEC (ddr_p, heap) *dependence_relations)
4280 struct data_dependence_relation *ddr;
4281 VEC (loop_p, heap) *loop_nest = NULL;
4283 for (i = 0; VEC_iterate (ddr_p, dependence_relations, i, ddr); i++)
4287 if (loop_nest == NULL)
4288 loop_nest = DDR_LOOP_NEST (ddr);
4290 gcc_assert (DDR_LOOP_NEST (ddr) == NULL
4291 || DDR_LOOP_NEST (ddr) == loop_nest);
4292 free_dependence_relation (ddr);
4296 VEC_free (loop_p, heap, loop_nest);
4297 VEC_free (ddr_p, heap, dependence_relations);
4300 /* Free the memory used by the data references from DATAREFS. */
4303 free_data_refs (VEC (data_reference_p, heap) *datarefs)
4306 struct data_reference *dr;
4308 for (i = 0; VEC_iterate (data_reference_p, datarefs, i, dr); i++)
4310 VEC_free (data_reference_p, heap, datarefs);