1 /* Alias analysis for trees.
2 Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009
3 Free Software Foundation, Inc.
4 Contributed by Diego Novillo <dnovillo@redhat.com>
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3, or (at your option)
13 GCC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
24 #include "coretypes.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
34 #include "langhooks.h"
37 #include "diagnostic.h"
38 #include "tree-dump.h"
40 #include "tree-flow.h"
41 #include "tree-inline.h"
42 #include "tree-pass.h"
45 #include "ipa-type-escape.h"
49 #include "pointer-set.h"
50 #include "alloc-pool.h"
51 #include "tree-ssa-alias.h"
53 /* Broad overview of how alias analysis on gimple works:
55 Statements clobbering or using memory are linked through the
56 virtual operand factored use-def chain. The virtual operand
57 is unique per function, its symbol is accessible via gimple_vop (cfun).
58 Virtual operands are used for efficiently walking memory statements
59 in the gimple IL and are useful for things like value-numbering as
60 a generation count for memory references.
62 SSA_NAME pointers may have associated points-to information
63 accessible via the SSA_NAME_PTR_INFO macro. Flow-insensitive
64 points-to information is (re-)computed by the TODO_rebuild_alias
65 pass manager todo. Points-to information is also used for more
66 precise tracking of call-clobbered and call-used variables and
67 related disambiguations.
69 This file contains functions for disambiguating memory references,
70 the so called alias-oracle and tools for walking of the gimple IL.
72 The main alias-oracle entry-points are
74 bool stmt_may_clobber_ref_p (gimple, tree)
76 This function queries if a statement may invalidate (parts of)
77 the memory designated by the reference tree argument.
79 bool ref_maybe_used_by_stmt_p (gimple, tree)
81 This function queries if a statement may need (parts of) the
82 memory designated by the reference tree argument.
84 There are variants of these functions that only handle the call
85 part of a statement, call_may_clobber_ref_p and ref_maybe_used_by_call_p.
86 Note that these do not disambiguate against a possible call lhs.
88 bool refs_may_alias_p (tree, tree)
90 This function tries to disambiguate two reference trees.
92 bool ptr_deref_may_alias_global_p (tree)
94 This function queries if dereferencing a pointer variable may
97 More low-level disambiguators are available and documented in
98 this file. Low-level disambiguators dealing with points-to
99 information are in tree-ssa-structalias.c. */
102 /* Query statistics for the different low-level disambiguators.
103 A high-level query may trigger multiple of them. */
106 unsigned HOST_WIDE_INT refs_may_alias_p_may_alias;
107 unsigned HOST_WIDE_INT refs_may_alias_p_no_alias;
108 unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_may_alias;
109 unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_no_alias;
110 unsigned HOST_WIDE_INT call_may_clobber_ref_p_may_alias;
111 unsigned HOST_WIDE_INT call_may_clobber_ref_p_no_alias;
115 dump_alias_stats (FILE *s)
117 fprintf (s, "\nAlias oracle query stats:\n");
118 fprintf (s, " refs_may_alias_p: "
119 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
120 HOST_WIDE_INT_PRINT_DEC" queries\n",
121 alias_stats.refs_may_alias_p_no_alias,
122 alias_stats.refs_may_alias_p_no_alias
123 + alias_stats.refs_may_alias_p_may_alias);
124 fprintf (s, " ref_maybe_used_by_call_p: "
125 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
126 HOST_WIDE_INT_PRINT_DEC" queries\n",
127 alias_stats.ref_maybe_used_by_call_p_no_alias,
128 alias_stats.refs_may_alias_p_no_alias
129 + alias_stats.ref_maybe_used_by_call_p_may_alias);
130 fprintf (s, " call_may_clobber_ref_p: "
131 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
132 HOST_WIDE_INT_PRINT_DEC" queries\n",
133 alias_stats.call_may_clobber_ref_p_no_alias,
134 alias_stats.call_may_clobber_ref_p_no_alias
135 + alias_stats.call_may_clobber_ref_p_may_alias);
139 /* Return true, if dereferencing PTR may alias with a global variable. */
142 ptr_deref_may_alias_global_p (tree ptr)
144 struct ptr_info_def *pi;
146 /* If we end up with a pointer constant here that may point
148 if (TREE_CODE (ptr) != SSA_NAME)
151 pi = SSA_NAME_PTR_INFO (ptr);
153 /* If we do not have points-to information for this variable,
158 /* ??? This does not use TBAA to prune globals ptr may not access. */
159 return pt_solution_includes_global (&pi->pt);
162 /* Return true if dereferencing PTR may alias DECL.
163 The caller is responsible for applying TBAA to see if PTR
164 may access DECL at all. */
167 ptr_deref_may_alias_decl_p (tree ptr, tree decl)
169 struct ptr_info_def *pi;
171 gcc_assert ((TREE_CODE (ptr) == SSA_NAME
172 || TREE_CODE (ptr) == ADDR_EXPR
173 || TREE_CODE (ptr) == INTEGER_CST)
174 && (TREE_CODE (decl) == VAR_DECL
175 || TREE_CODE (decl) == PARM_DECL
176 || TREE_CODE (decl) == RESULT_DECL));
178 /* Non-aliased variables can not be pointed to. */
179 if (!may_be_aliased (decl))
182 /* ADDR_EXPR pointers either just offset another pointer or directly
183 specify the pointed-to set. */
184 if (TREE_CODE (ptr) == ADDR_EXPR)
186 tree base = get_base_address (TREE_OPERAND (ptr, 0));
188 && INDIRECT_REF_P (base))
189 ptr = TREE_OPERAND (base, 0);
192 return operand_equal_p (base, decl, 0);
194 && CONSTANT_CLASS_P (base))
200 /* We can end up with dereferencing constant pointers.
201 Just bail out in this case. */
202 if (TREE_CODE (ptr) == INTEGER_CST)
205 /* If we do not have useful points-to information for this pointer
206 we cannot disambiguate anything else. */
207 pi = SSA_NAME_PTR_INFO (ptr);
211 /* If the decl can be used as a restrict tag and we have a restrict
212 pointer and that pointers points-to set doesn't contain this decl
213 then they can't alias. */
214 if (DECL_RESTRICTED_P (decl)
215 && TYPE_RESTRICT (TREE_TYPE (ptr))
216 && pi->pt.vars_contains_restrict)
217 return bitmap_bit_p (pi->pt.vars, DECL_UID (decl));
219 return pt_solution_includes (&pi->pt, decl);
222 /* Return true if dereferenced PTR1 and PTR2 may alias.
223 The caller is responsible for applying TBAA to see if accesses
224 through PTR1 and PTR2 may conflict at all. */
227 ptr_derefs_may_alias_p (tree ptr1, tree ptr2)
229 struct ptr_info_def *pi1, *pi2;
231 gcc_assert ((TREE_CODE (ptr1) == SSA_NAME
232 || TREE_CODE (ptr1) == ADDR_EXPR
233 || TREE_CODE (ptr1) == INTEGER_CST)
234 && (TREE_CODE (ptr2) == SSA_NAME
235 || TREE_CODE (ptr2) == ADDR_EXPR
236 || TREE_CODE (ptr2) == INTEGER_CST));
238 /* ADDR_EXPR pointers either just offset another pointer or directly
239 specify the pointed-to set. */
240 if (TREE_CODE (ptr1) == ADDR_EXPR)
242 tree base = get_base_address (TREE_OPERAND (ptr1, 0));
244 && INDIRECT_REF_P (base))
245 ptr1 = TREE_OPERAND (base, 0);
248 return ptr_deref_may_alias_decl_p (ptr2, base);
252 if (TREE_CODE (ptr2) == ADDR_EXPR)
254 tree base = get_base_address (TREE_OPERAND (ptr2, 0));
256 && INDIRECT_REF_P (base))
257 ptr2 = TREE_OPERAND (base, 0);
260 return ptr_deref_may_alias_decl_p (ptr1, base);
265 /* We can end up with dereferencing constant pointers.
266 Just bail out in this case. */
267 if (TREE_CODE (ptr1) == INTEGER_CST
268 || TREE_CODE (ptr2) == INTEGER_CST)
271 /* We may end up with two empty points-to solutions for two same pointers.
272 In this case we still want to say both pointers alias, so shortcut
277 /* If we do not have useful points-to information for either pointer
278 we cannot disambiguate anything else. */
279 pi1 = SSA_NAME_PTR_INFO (ptr1);
280 pi2 = SSA_NAME_PTR_INFO (ptr2);
284 /* If both pointers are restrict-qualified try to disambiguate
285 with restrict information. */
286 if (TYPE_RESTRICT (TREE_TYPE (ptr1))
287 && TYPE_RESTRICT (TREE_TYPE (ptr2))
288 && !pt_solutions_same_restrict_base (&pi1->pt, &pi2->pt))
291 /* ??? This does not use TBAA to prune decls from the intersection
292 that not both pointers may access. */
293 return pt_solutions_intersect (&pi1->pt, &pi2->pt);
296 /* Return true if dereferencing PTR may alias *REF.
297 The caller is responsible for applying TBAA to see if PTR
298 may access *REF at all. */
301 ptr_deref_may_alias_ref_p_1 (tree ptr, ao_ref *ref)
303 tree base = ao_ref_base (ref);
305 if (INDIRECT_REF_P (base))
306 return ptr_derefs_may_alias_p (ptr, TREE_OPERAND (base, 0));
307 else if (SSA_VAR_P (base))
308 return ptr_deref_may_alias_decl_p (ptr, base);
314 /* Dump alias information on FILE. */
317 dump_alias_info (FILE *file)
321 = lang_hooks.decl_printable_name (current_function_decl, 2);
322 referenced_var_iterator rvi;
325 fprintf (file, "\n\nAlias information for %s\n\n", funcname);
327 fprintf (file, "Aliased symbols\n\n");
329 FOR_EACH_REFERENCED_VAR (var, rvi)
331 if (may_be_aliased (var))
332 dump_variable (file, var);
335 fprintf (file, "\nCall clobber information\n");
337 fprintf (file, "\nESCAPED");
338 dump_points_to_solution (file, &cfun->gimple_df->escaped);
339 fprintf (file, "\nCALLUSED");
340 dump_points_to_solution (file, &cfun->gimple_df->callused);
342 fprintf (file, "\n\nFlow-insensitive points-to information\n\n");
344 for (i = 1; i < num_ssa_names; i++)
346 tree ptr = ssa_name (i);
347 struct ptr_info_def *pi;
350 || SSA_NAME_IN_FREE_LIST (ptr))
353 pi = SSA_NAME_PTR_INFO (ptr);
355 dump_points_to_info_for (file, ptr);
358 fprintf (file, "\n");
362 /* Dump alias information on stderr. */
365 debug_alias_info (void)
367 dump_alias_info (stderr);
371 /* Return the alias information associated with pointer T. It creates a
372 new instance if none existed. */
374 struct ptr_info_def *
375 get_ptr_info (tree t)
377 struct ptr_info_def *pi;
379 gcc_assert (POINTER_TYPE_P (TREE_TYPE (t)));
381 pi = SSA_NAME_PTR_INFO (t);
384 pi = GGC_CNEW (struct ptr_info_def);
385 pt_solution_reset (&pi->pt);
386 SSA_NAME_PTR_INFO (t) = pi;
392 /* Dump the points-to set *PT into FILE. */
395 dump_points_to_solution (FILE *file, struct pt_solution *pt)
398 fprintf (file, ", points-to anything");
401 fprintf (file, ", points-to non-local");
404 fprintf (file, ", points-to escaped");
407 fprintf (file, ", points-to NULL");
411 fprintf (file, ", points-to vars: ");
412 dump_decl_set (file, pt->vars);
413 if (pt->vars_contains_global)
414 fprintf (file, " (includes global vars)");
418 /* Dump points-to information for SSA_NAME PTR into FILE. */
421 dump_points_to_info_for (FILE *file, tree ptr)
423 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
425 print_generic_expr (file, ptr, dump_flags);
428 dump_points_to_solution (file, &pi->pt);
430 fprintf (file, ", points-to anything");
432 fprintf (file, "\n");
436 /* Dump points-to information for VAR into stderr. */
439 debug_points_to_info_for (tree var)
441 dump_points_to_info_for (stderr, var);
445 /* Initializes the alias-oracle reference representation *R from REF. */
448 ao_ref_init (ao_ref *r, tree ref)
455 r->ref_alias_set = -1;
456 r->base_alias_set = -1;
459 /* Returns the base object of the memory reference *REF. */
462 ao_ref_base (ao_ref *ref)
466 ref->base = get_ref_base_and_extent (ref->ref, &ref->offset, &ref->size,
471 /* Returns the base object alias set of the memory reference *REF. */
473 static alias_set_type ATTRIBUTE_UNUSED
474 ao_ref_base_alias_set (ao_ref *ref)
476 if (ref->base_alias_set != -1)
477 return ref->base_alias_set;
478 ref->base_alias_set = get_alias_set (ao_ref_base (ref));
479 return ref->base_alias_set;
482 /* Returns the reference alias set of the memory reference *REF. */
485 ao_ref_alias_set (ao_ref *ref)
487 if (ref->ref_alias_set != -1)
488 return ref->ref_alias_set;
489 ref->ref_alias_set = get_alias_set (ref->ref);
490 return ref->ref_alias_set;
493 /* Init an alias-oracle reference representation from a gimple pointer
494 PTR and a gimple size SIZE in bytes. If SIZE is NULL_TREE the the
495 size is assumed to be unknown. The access is assumed to be only
496 to or after of the pointer target, not before it. */
499 ao_ref_init_from_ptr_and_size (ao_ref *ref, tree ptr, tree size)
501 HOST_WIDE_INT t1, t2;
502 ref->ref = NULL_TREE;
503 if (TREE_CODE (ptr) == ADDR_EXPR)
504 ref->base = get_ref_base_and_extent (TREE_OPERAND (ptr, 0),
505 &ref->offset, &t1, &t2);
508 ref->base = build1 (INDIRECT_REF, char_type_node, ptr);
512 && host_integerp (size, 0)
513 && TREE_INT_CST_LOW (size) * 8 / 8 == TREE_INT_CST_LOW (size))
514 ref->max_size = ref->size = TREE_INT_CST_LOW (size) * 8;
516 ref->max_size = ref->size = -1;
517 ref->ref_alias_set = 0;
518 ref->base_alias_set = 0;
521 /* Return 1 if TYPE1 and TYPE2 are to be considered equivalent for the
522 purpose of TBAA. Return 0 if they are distinct and -1 if we cannot
526 same_type_for_tbaa (tree type1, tree type2)
528 type1 = TYPE_MAIN_VARIANT (type1);
529 type2 = TYPE_MAIN_VARIANT (type2);
531 /* If we would have to do structural comparison bail out. */
532 if (TYPE_STRUCTURAL_EQUALITY_P (type1)
533 || TYPE_STRUCTURAL_EQUALITY_P (type2))
536 /* Compare the canonical types. */
537 if (TYPE_CANONICAL (type1) == TYPE_CANONICAL (type2))
540 /* ??? Array types are not properly unified in all cases as we have
541 spurious changes in the index types for example. Removing this
542 causes all sorts of problems with the Fortran frontend. */
543 if (TREE_CODE (type1) == ARRAY_TYPE
544 && TREE_CODE (type2) == ARRAY_TYPE)
547 /* The types are known to be not equal. */
551 /* Determine if the two component references REF1 and REF2 which are
552 based on access types TYPE1 and TYPE2 and of which at least one is based
553 on an indirect reference may alias. */
556 aliasing_component_refs_p (tree ref1, tree type1,
557 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
558 tree ref2, tree type2,
559 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
561 /* If one reference is a component references through pointers try to find a
562 common base and apply offset based disambiguation. This handles
564 struct A { int i; int j; } *q;
565 struct B { struct A a; int k; } *p;
566 disambiguating q->i and p->a.j. */
570 /* Now search for the type1 in the access path of ref2. This
571 would be a common base for doing offset based disambiguation on. */
573 while (handled_component_p (*refp)
574 && same_type_for_tbaa (TREE_TYPE (*refp), type1) == 0)
575 refp = &TREE_OPERAND (*refp, 0);
576 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type1);
577 /* If we couldn't compare types we have to bail out. */
580 else if (same_p == 1)
582 HOST_WIDE_INT offadj, sztmp, msztmp;
583 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
585 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
587 /* If we didn't find a common base, try the other way around. */
589 while (handled_component_p (*refp)
590 && same_type_for_tbaa (TREE_TYPE (*refp), type2) == 0)
591 refp = &TREE_OPERAND (*refp, 0);
592 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type2);
593 /* If we couldn't compare types we have to bail out. */
596 else if (same_p == 1)
598 HOST_WIDE_INT offadj, sztmp, msztmp;
599 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
601 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
604 /* We haven't found any common base to apply offset-based disambiguation.
606 1. The base access types have the same alias set. This can happen
607 in Ada when a function with an unconstrained parameter passed by
608 reference is called on a constrained object and inlined: the types
609 have the same alias set but aren't equivalent. The references may
611 2. The base access types don't have the same alias set, i.e. one set
612 is a subset of the other. We have proved that B1 is not in the
613 access path B2.path and that B2 is not in the access path B1.path
614 so the references may not alias. */
615 return get_alias_set (type1) == get_alias_set (type2);
618 /* Return true if two memory references based on the variables BASE1
619 and BASE2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
620 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. */
623 decl_refs_may_alias_p (tree base1,
624 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
626 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
628 gcc_assert (SSA_VAR_P (base1) && SSA_VAR_P (base2));
630 /* If both references are based on different variables, they cannot alias. */
631 if (!operand_equal_p (base1, base2, 0))
634 /* If both references are based on the same variable, they cannot alias if
635 the accesses do not overlap. */
636 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
639 /* Return true if an indirect reference based on *PTR1 constrained
640 to [OFFSET1, OFFSET1 + MAX_SIZE1) may alias a variable based on BASE2
641 constrained to [OFFSET2, OFFSET2 + MAX_SIZE2). *PTR1 and BASE2 have
642 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
643 in which case they are computed on-demand. REF1 and REF2
644 if non-NULL are the complete memory reference trees. */
647 indirect_ref_may_alias_decl_p (tree ref1, tree ptr1,
648 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
649 alias_set_type base1_alias_set,
650 tree ref2, tree base2,
651 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
652 alias_set_type base2_alias_set)
654 /* If only one reference is based on a variable, they cannot alias if
655 the pointer access is beyond the extent of the variable access.
656 (the pointer base cannot validly point to an offset less than zero
658 They also cannot alias if the pointer may not point to the decl. */
660 && !ranges_overlap_p (offset1, max_size1, 0, offset2 + max_size2))
662 if (!ptr_deref_may_alias_decl_p (ptr1, base2))
665 /* Disambiguations that rely on strict aliasing rules follow. */
666 if (!flag_strict_aliasing)
669 /* If the alias set for a pointer access is zero all bets are off. */
670 if (base1_alias_set == -1)
671 base1_alias_set = get_deref_alias_set (ptr1);
672 if (base1_alias_set == 0)
674 if (base2_alias_set == -1)
675 base2_alias_set = get_alias_set (base2);
677 /* If both references are through the same type, they do not alias
678 if the accesses do not overlap. This does extra disambiguation
679 for mixed/pointer accesses but requires strict aliasing. */
680 if (same_type_for_tbaa (TREE_TYPE (TREE_TYPE (ptr1)),
681 TREE_TYPE (base2)) == 1)
682 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
684 /* The only way to access a variable is through a pointer dereference
685 of the same alias set or a subset of it. */
686 if (base1_alias_set != base2_alias_set
687 && !alias_set_subset_of (base1_alias_set, base2_alias_set))
690 /* Do access-path based disambiguation. */
692 && handled_component_p (ref1)
693 && handled_component_p (ref2))
694 return aliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)),
696 ref2, TREE_TYPE (base2),
702 /* Return true if two indirect references based on *PTR1
703 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
704 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have
705 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
706 in which case they are computed on-demand. REF1 and REF2
707 if non-NULL are the complete memory reference trees. */
710 indirect_refs_may_alias_p (tree ref1, tree ptr1,
711 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
712 alias_set_type base1_alias_set,
713 tree ref2, tree ptr2,
714 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
715 alias_set_type base2_alias_set)
717 /* If both bases are based on pointers they cannot alias if they may not
718 point to the same memory object or if they point to the same object
719 and the accesses do not overlap. */
720 if (operand_equal_p (ptr1, ptr2, 0))
721 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
722 if (!ptr_derefs_may_alias_p (ptr1, ptr2))
725 /* Disambiguations that rely on strict aliasing rules follow. */
726 if (!flag_strict_aliasing)
729 /* If the alias set for a pointer access is zero all bets are off. */
730 if (base1_alias_set == -1)
731 base1_alias_set = get_deref_alias_set (ptr1);
732 if (base1_alias_set == 0)
734 if (base2_alias_set == -1)
735 base2_alias_set = get_deref_alias_set (ptr2);
736 if (base2_alias_set == 0)
739 /* If both references are through the same type, they do not alias
740 if the accesses do not overlap. This does extra disambiguation
741 for mixed/pointer accesses but requires strict aliasing. */
742 if (same_type_for_tbaa (TREE_TYPE (TREE_TYPE (ptr1)),
743 TREE_TYPE (TREE_TYPE (ptr2))) == 1)
744 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
746 /* Do type-based disambiguation. */
747 if (base1_alias_set != base2_alias_set
748 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
751 /* Do access-path based disambiguation. */
753 && handled_component_p (ref1)
754 && handled_component_p (ref2))
755 return aliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)),
757 ref2, TREE_TYPE (TREE_TYPE (ptr2)),
763 /* Return true, if the two memory references REF1 and REF2 may alias. */
766 refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
769 HOST_WIDE_INT offset1 = 0, offset2 = 0;
770 HOST_WIDE_INT size1 = -1, size2 = -1;
771 HOST_WIDE_INT max_size1 = -1, max_size2 = -1;
772 bool var1_p, var2_p, ind1_p, ind2_p;
775 gcc_assert ((!ref1->ref
776 || SSA_VAR_P (ref1->ref)
777 || handled_component_p (ref1->ref)
778 || INDIRECT_REF_P (ref1->ref)
779 || TREE_CODE (ref1->ref) == TARGET_MEM_REF
780 || TREE_CODE (ref1->ref) == CONST_DECL)
782 || SSA_VAR_P (ref2->ref)
783 || handled_component_p (ref2->ref)
784 || INDIRECT_REF_P (ref2->ref)
785 || TREE_CODE (ref2->ref) == TARGET_MEM_REF
786 || TREE_CODE (ref2->ref) == CONST_DECL));
788 /* Decompose the references into their base objects and the access. */
789 base1 = ao_ref_base (ref1);
790 offset1 = ref1->offset;
792 max_size1 = ref1->max_size;
793 base2 = ao_ref_base (ref2);
794 offset2 = ref2->offset;
796 max_size2 = ref2->max_size;
798 /* We can end up with registers or constants as bases for example from
799 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
800 which is seen as a struct copy. */
801 if (TREE_CODE (base1) == SSA_NAME
802 || TREE_CODE (base2) == SSA_NAME
803 || TREE_CODE (base1) == CONST_DECL
804 || TREE_CODE (base2) == CONST_DECL
805 || is_gimple_min_invariant (base1)
806 || is_gimple_min_invariant (base2))
809 /* We can end up refering to code via function decls. As we likely
810 do not properly track code aliases conservatively bail out. */
811 if (TREE_CODE (base1) == FUNCTION_DECL
812 || TREE_CODE (base2) == FUNCTION_DECL)
815 /* Defer to simple offset based disambiguation if we have
816 references based on two decls. Do this before defering to
817 TBAA to handle must-alias cases in conformance with the
818 GCC extension of allowing type-punning through unions. */
819 var1_p = SSA_VAR_P (base1);
820 var2_p = SSA_VAR_P (base2);
821 if (var1_p && var2_p)
822 return decl_refs_may_alias_p (base1, offset1, max_size1,
823 base2, offset2, max_size2);
825 /* First defer to TBAA if possible. */
827 && flag_strict_aliasing
828 && !alias_sets_conflict_p (ao_ref_alias_set (ref1),
829 ao_ref_alias_set (ref2)))
832 /* If one reference is a TARGET_MEM_REF weird things are allowed. Still
833 TBAA disambiguation based on the access type is possible, so bail
834 out only after that check. */
835 if ((ref1->ref && TREE_CODE (ref1->ref) == TARGET_MEM_REF)
836 || (ref2->ref && TREE_CODE (ref2->ref) == TARGET_MEM_REF))
839 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */
840 ind1_p = INDIRECT_REF_P (base1);
841 ind2_p = INDIRECT_REF_P (base2);
842 set = tbaa_p ? -1 : 0;
843 if (var1_p && ind2_p)
844 return indirect_ref_may_alias_decl_p (ref2->ref, TREE_OPERAND (base2, 0),
845 offset2, max_size2, set,
847 offset1, max_size1, set);
848 else if (ind1_p && var2_p)
849 return indirect_ref_may_alias_decl_p (ref1->ref, TREE_OPERAND (base1, 0),
850 offset1, max_size1, set,
852 offset2, max_size2, set);
853 else if (ind1_p && ind2_p)
854 return indirect_refs_may_alias_p (ref1->ref, TREE_OPERAND (base1, 0),
855 offset1, max_size1, set,
856 ref2->ref, TREE_OPERAND (base2, 0),
857 offset2, max_size2, set);
863 refs_may_alias_p (tree ref1, tree ref2)
867 ao_ref_init (&r1, ref1);
868 ao_ref_init (&r2, ref2);
869 res = refs_may_alias_p_1 (&r1, &r2, true);
871 ++alias_stats.refs_may_alias_p_may_alias;
873 ++alias_stats.refs_may_alias_p_no_alias;
877 /* Returns true if there is a anti-dependence for the STORE that
878 executes after the LOAD. */
881 refs_anti_dependent_p (tree load, tree store)
884 ao_ref_init (&r1, load);
885 ao_ref_init (&r2, store);
886 return refs_may_alias_p_1 (&r1, &r2, false);
889 /* Returns true if there is a output dependence for the stores
890 STORE1 and STORE2. */
893 refs_output_dependent_p (tree store1, tree store2)
896 ao_ref_init (&r1, store1);
897 ao_ref_init (&r2, store2);
898 return refs_may_alias_p_1 (&r1, &r2, false);
901 /* If the call CALL may use the memory reference REF return true,
902 otherwise return false. */
905 ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
909 int flags = gimple_call_flags (call);
911 /* Const functions without a static chain do not implicitly use memory. */
912 if (!gimple_call_chain (call)
913 && (flags & (ECF_CONST|ECF_NOVOPS)))
916 base = ao_ref_base (ref);
920 /* If the reference is based on a decl that is not aliased the call
921 cannot possibly use it. */
923 && !may_be_aliased (base)
924 /* But local statics can be used through recursion. */
925 && !is_global_var (base))
928 callee = gimple_call_fndecl (call);
930 /* Handle those builtin functions explicitly that do not act as
931 escape points. See tree-ssa-structalias.c:find_func_aliases
932 for the list of builtins we might need to handle here. */
933 if (callee != NULL_TREE
934 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
935 switch (DECL_FUNCTION_CODE (callee))
937 /* All the following functions clobber memory pointed to by
938 their first argument. */
939 case BUILT_IN_STRCPY:
940 case BUILT_IN_STRNCPY:
941 case BUILT_IN_MEMCPY:
942 case BUILT_IN_MEMMOVE:
943 case BUILT_IN_MEMPCPY:
944 case BUILT_IN_STPCPY:
945 case BUILT_IN_STPNCPY:
946 case BUILT_IN_STRCAT:
947 case BUILT_IN_STRNCAT:
950 tree size = NULL_TREE;
951 if (gimple_call_num_args (call) == 3)
952 size = gimple_call_arg (call, 2);
953 ao_ref_init_from_ptr_and_size (&dref,
954 gimple_call_arg (call, 1),
956 return refs_may_alias_p_1 (&dref, ref, false);
961 tree size = gimple_call_arg (call, 2);
962 ao_ref_init_from_ptr_and_size (&dref,
963 gimple_call_arg (call, 0),
965 return refs_may_alias_p_1 (&dref, ref, false);
967 /* The following builtins do not read from memory. */
969 case BUILT_IN_MEMSET:
971 case BUILT_IN_FREXPF:
972 case BUILT_IN_FREXPL:
973 case BUILT_IN_GAMMA_R:
974 case BUILT_IN_GAMMAF_R:
975 case BUILT_IN_GAMMAL_R:
976 case BUILT_IN_LGAMMA_R:
977 case BUILT_IN_LGAMMAF_R:
978 case BUILT_IN_LGAMMAL_R:
982 case BUILT_IN_REMQUO:
983 case BUILT_IN_REMQUOF:
984 case BUILT_IN_REMQUOL:
985 case BUILT_IN_SINCOS:
986 case BUILT_IN_SINCOSF:
987 case BUILT_IN_SINCOSL:
991 /* Fallthru to general call handling. */;
994 /* Check if base is a global static variable that is not read
996 if (TREE_CODE (base) == VAR_DECL
997 && TREE_STATIC (base)
998 && !TREE_PUBLIC (base))
1002 if (callee != NULL_TREE
1004 = ipa_reference_get_not_read_global (cgraph_node (callee)))
1005 && bitmap_bit_p (not_read, DECL_UID (base)))
1009 /* If the base variable is call-used or call-clobbered then
1011 if (flags & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS))
1015 if (is_call_used (base))
1018 else if (INDIRECT_REF_P (base)
1019 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1021 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1025 if (pt_solution_includes_global (&pi->pt)
1026 || pt_solutions_intersect (&cfun->gimple_df->callused, &pi->pt)
1027 || pt_solutions_intersect (&cfun->gimple_df->escaped, &pi->pt))
1037 if (is_call_clobbered (base))
1040 else if (INDIRECT_REF_P (base)
1041 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1043 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1047 if (pt_solution_includes_global (&pi->pt)
1048 || pt_solutions_intersect (&cfun->gimple_df->escaped, &pi->pt))
1055 /* Inspect call arguments for passed-by-value aliases. */
1057 for (i = 0; i < gimple_call_num_args (call); ++i)
1059 tree op = gimple_call_arg (call, i);
1061 if (TREE_CODE (op) == WITH_SIZE_EXPR)
1062 op = TREE_OPERAND (op, 0);
1064 if (TREE_CODE (op) != SSA_NAME
1065 && !is_gimple_min_invariant (op))
1068 ao_ref_init (&r, op);
1069 if (refs_may_alias_p_1 (&r, ref, true))
1078 ref_maybe_used_by_call_p (gimple call, tree ref)
1082 ao_ref_init (&r, ref);
1083 res = ref_maybe_used_by_call_p_1 (call, &r);
1085 ++alias_stats.ref_maybe_used_by_call_p_may_alias;
1087 ++alias_stats.ref_maybe_used_by_call_p_no_alias;
1092 /* If the statement STMT may use the memory reference REF return
1093 true, otherwise return false. */
1096 ref_maybe_used_by_stmt_p (gimple stmt, tree ref)
1098 if (is_gimple_assign (stmt))
1102 /* All memory assign statements are single. */
1103 if (!gimple_assign_single_p (stmt))
1106 rhs = gimple_assign_rhs1 (stmt);
1107 if (is_gimple_reg (rhs)
1108 || is_gimple_min_invariant (rhs)
1109 || gimple_assign_rhs_code (stmt) == CONSTRUCTOR)
1112 return refs_may_alias_p (rhs, ref);
1114 else if (is_gimple_call (stmt))
1115 return ref_maybe_used_by_call_p (stmt, ref);
1120 /* If the call in statement CALL may clobber the memory reference REF
1121 return true, otherwise return false. */
1124 call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
1129 /* If the call is pure or const it cannot clobber anything. */
1130 if (gimple_call_flags (call)
1131 & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS))
1134 base = ao_ref_base (ref);
1138 if (TREE_CODE (base) == SSA_NAME
1139 || CONSTANT_CLASS_P (base))
1142 /* If the reference is based on a decl that is not aliased the call
1143 cannot possibly clobber it. */
1145 && !may_be_aliased (base)
1146 /* But local non-readonly statics can be modified through recursion
1147 or the call may implement a threading barrier which we must
1148 treat as may-def. */
1149 && (TREE_READONLY (base)
1150 || !is_global_var (base)))
1153 callee = gimple_call_fndecl (call);
1155 /* Handle those builtin functions explicitly that do not act as
1156 escape points. See tree-ssa-structalias.c:find_func_aliases
1157 for the list of builtins we might need to handle here. */
1158 if (callee != NULL_TREE
1159 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1160 switch (DECL_FUNCTION_CODE (callee))
1162 /* All the following functions clobber memory pointed to by
1163 their first argument. */
1164 case BUILT_IN_STRCPY:
1165 case BUILT_IN_STRNCPY:
1166 case BUILT_IN_MEMCPY:
1167 case BUILT_IN_MEMMOVE:
1168 case BUILT_IN_MEMPCPY:
1169 case BUILT_IN_STPCPY:
1170 case BUILT_IN_STPNCPY:
1171 case BUILT_IN_STRCAT:
1172 case BUILT_IN_STRNCAT:
1173 case BUILT_IN_MEMSET:
1176 tree size = NULL_TREE;
1177 if (gimple_call_num_args (call) == 3)
1178 size = gimple_call_arg (call, 2);
1179 ao_ref_init_from_ptr_and_size (&dref,
1180 gimple_call_arg (call, 0),
1182 return refs_may_alias_p_1 (&dref, ref, false);
1184 case BUILT_IN_BCOPY:
1187 tree size = gimple_call_arg (call, 2);
1188 ao_ref_init_from_ptr_and_size (&dref,
1189 gimple_call_arg (call, 1),
1191 return refs_may_alias_p_1 (&dref, ref, false);
1193 /* Freeing memory kills the pointed-to memory. More importantly
1194 the call has to serve as a barrier for moving loads and stores
1198 tree ptr = gimple_call_arg (call, 0);
1199 return ptr_deref_may_alias_ref_p_1 (ptr, ref);
1201 case BUILT_IN_GAMMA_R:
1202 case BUILT_IN_GAMMAF_R:
1203 case BUILT_IN_GAMMAL_R:
1204 case BUILT_IN_LGAMMA_R:
1205 case BUILT_IN_LGAMMAF_R:
1206 case BUILT_IN_LGAMMAL_R:
1208 tree out = gimple_call_arg (call, 1);
1209 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1211 if (flag_errno_math)
1215 case BUILT_IN_FREXP:
1216 case BUILT_IN_FREXPF:
1217 case BUILT_IN_FREXPL:
1219 case BUILT_IN_MODFF:
1220 case BUILT_IN_MODFL:
1222 tree out = gimple_call_arg (call, 1);
1223 return ptr_deref_may_alias_ref_p_1 (out, ref);
1225 case BUILT_IN_REMQUO:
1226 case BUILT_IN_REMQUOF:
1227 case BUILT_IN_REMQUOL:
1229 tree out = gimple_call_arg (call, 2);
1230 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1232 if (flag_errno_math)
1236 case BUILT_IN_SINCOS:
1237 case BUILT_IN_SINCOSF:
1238 case BUILT_IN_SINCOSL:
1240 tree sin = gimple_call_arg (call, 1);
1241 tree cos = gimple_call_arg (call, 2);
1242 return (ptr_deref_may_alias_ref_p_1 (sin, ref)
1243 || ptr_deref_may_alias_ref_p_1 (cos, ref));
1246 /* Fallthru to general call handling. */;
1249 /* Check if base is a global static variable that is not written
1251 if (callee != NULL_TREE
1252 && TREE_CODE (base) == VAR_DECL
1253 && TREE_STATIC (base)
1254 && !TREE_PUBLIC (base))
1259 = ipa_reference_get_not_written_global (cgraph_node (callee)))
1260 && bitmap_bit_p (not_written, DECL_UID (base)))
1265 return is_call_clobbered (base);
1266 else if (INDIRECT_REF_P (base)
1267 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1269 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1273 return (pt_solution_includes_global (&pi->pt)
1274 || pt_solutions_intersect (&cfun->gimple_df->escaped, &pi->pt));
1280 static bool ATTRIBUTE_UNUSED
1281 call_may_clobber_ref_p (gimple call, tree ref)
1285 ao_ref_init (&r, ref);
1286 res = call_may_clobber_ref_p_1 (call, &r);
1288 ++alias_stats.call_may_clobber_ref_p_may_alias;
1290 ++alias_stats.call_may_clobber_ref_p_no_alias;
1295 /* If the statement STMT may clobber the memory reference REF return true,
1296 otherwise return false. */
1299 stmt_may_clobber_ref_p_1 (gimple stmt, ao_ref *ref)
1301 if (is_gimple_call (stmt))
1303 tree lhs = gimple_call_lhs (stmt);
1305 && !is_gimple_reg (lhs))
1308 ao_ref_init (&r, lhs);
1309 if (refs_may_alias_p_1 (ref, &r, true))
1313 return call_may_clobber_ref_p_1 (stmt, ref);
1315 else if (is_gimple_assign (stmt))
1318 ao_ref_init (&r, gimple_assign_lhs (stmt));
1319 return refs_may_alias_p_1 (ref, &r, true);
1321 else if (gimple_code (stmt) == GIMPLE_ASM)
1328 stmt_may_clobber_ref_p (gimple stmt, tree ref)
1331 ao_ref_init (&r, ref);
1332 return stmt_may_clobber_ref_p_1 (stmt, &r);
1336 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand
1337 TARGET or a statement clobbering the memory reference REF in which
1338 case false is returned. The walk starts with VUSE, one argument of PHI. */
1341 maybe_skip_until (gimple phi, tree target, ao_ref *ref,
1342 tree vuse, bitmap *visited)
1345 *visited = BITMAP_ALLOC (NULL);
1347 bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi)));
1349 /* Walk until we hit the target. */
1350 while (vuse != target)
1352 gimple def_stmt = SSA_NAME_DEF_STMT (vuse);
1353 /* Recurse for PHI nodes. */
1354 if (gimple_code (def_stmt) == GIMPLE_PHI)
1356 /* An already visited PHI node ends the walk successfully. */
1357 if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt))))
1359 vuse = get_continuation_for_phi (def_stmt, ref, visited);
1364 /* A clobbering statement or the end of the IL ends it failing. */
1365 else if (gimple_nop_p (def_stmt)
1366 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1368 vuse = gimple_vuse (def_stmt);
1373 /* Starting from a PHI node for the virtual operand of the memory reference
1374 REF find a continuation virtual operand that allows to continue walking
1375 statements dominating PHI skipping only statements that cannot possibly
1376 clobber REF. Returns NULL_TREE if no suitable virtual operand can
1380 get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited)
1382 unsigned nargs = gimple_phi_num_args (phi);
1384 /* Through a single-argument PHI we can simply look through. */
1386 return PHI_ARG_DEF (phi, 0);
1388 /* For two arguments try to skip non-aliasing code until we hit
1389 the phi argument definition that dominates the other one. */
1392 tree arg0 = PHI_ARG_DEF (phi, 0);
1393 tree arg1 = PHI_ARG_DEF (phi, 1);
1394 gimple def0 = SSA_NAME_DEF_STMT (arg0);
1395 gimple def1 = SSA_NAME_DEF_STMT (arg1);
1400 else if (gimple_nop_p (def0)
1401 || (!gimple_nop_p (def1)
1402 && dominated_by_p (CDI_DOMINATORS,
1403 gimple_bb (def1), gimple_bb (def0))))
1405 if (maybe_skip_until (phi, arg0, ref, arg1, visited))
1408 else if (gimple_nop_p (def1)
1409 || dominated_by_p (CDI_DOMINATORS,
1410 gimple_bb (def0), gimple_bb (def1)))
1412 if (maybe_skip_until (phi, arg1, ref, arg0, visited))
1415 /* Special case of a diamond:
1417 goto (cond) ? L1 : L2
1418 L1: store1 = ... #MEM_2 = vuse(MEM_1)
1420 L2: store2 = ... #MEM_3 = vuse(MEM_1)
1421 L3: MEM_4 = PHI<MEM_2, MEM_3>
1422 We were called with the PHI at L3, MEM_2 and MEM_3 don't
1423 dominate each other, but still we can easily skip this PHI node
1424 if we recognize that the vuse MEM operand is the same for both,
1425 and that we can skip both statements (they don't clobber us).
1426 This is still linear. Don't use maybe_skip_until, that might
1427 potentially be slow. */
1428 else if ((common_vuse = gimple_vuse (def0))
1429 && common_vuse == gimple_vuse (def1))
1431 if (!stmt_may_clobber_ref_p_1 (def0, ref)
1432 && !stmt_may_clobber_ref_p_1 (def1, ref))
1440 /* Based on the memory reference REF and its virtual use VUSE call
1441 WALKER for each virtual use that is equivalent to VUSE, including VUSE
1442 itself. That is, for each virtual use for which its defining statement
1443 does not clobber REF.
1445 WALKER is called with REF, the current virtual use and DATA. If
1446 WALKER returns non-NULL the walk stops and its result is returned.
1447 At the end of a non-successful walk NULL is returned.
1449 TRANSLATE if non-NULL is called with a pointer to REF, the virtual
1450 use which definition is a statement that may clobber REF and DATA.
1451 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
1452 If TRANSLATE returns non-NULL the walk stops and its result is returned.
1453 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
1454 to adjust REF and *DATA to make that valid.
1456 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
1459 walk_non_aliased_vuses (ao_ref *ref, tree vuse,
1460 void *(*walker)(ao_ref *, tree, void *),
1461 void *(*translate)(ao_ref *, tree, void *), void *data)
1463 bitmap visited = NULL;
1466 timevar_push (TV_ALIAS_STMT_WALK);
1472 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1473 res = (*walker) (ref, vuse, data);
1477 def_stmt = SSA_NAME_DEF_STMT (vuse);
1478 if (gimple_nop_p (def_stmt))
1480 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1481 vuse = get_continuation_for_phi (def_stmt, ref, &visited);
1484 if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
1488 res = (*translate) (ref, vuse, data);
1489 /* Failed lookup and translation. */
1490 if (res == (void *)-1)
1495 /* Lookup succeeded. */
1496 else if (res != NULL)
1498 /* Translation succeeded, continue walking. */
1500 vuse = gimple_vuse (def_stmt);
1506 BITMAP_FREE (visited);
1508 timevar_pop (TV_ALIAS_STMT_WALK);
1514 /* Based on the memory reference REF call WALKER for each vdef which
1515 defining statement may clobber REF, starting with VDEF. If REF
1516 is NULL_TREE, each defining statement is visited.
1518 WALKER is called with REF, the current vdef and DATA. If WALKER
1519 returns true the walk is stopped, otherwise it continues.
1521 At PHI nodes walk_aliased_vdefs forks into one walk for reach
1522 PHI argument (but only one walk continues on merge points), the
1523 return value is true if any of the walks was successful.
1525 The function returns the number of statements walked. */
1528 walk_aliased_vdefs_1 (ao_ref *ref, tree vdef,
1529 bool (*walker)(ao_ref *, tree, void *), void *data,
1530 bitmap *visited, unsigned int cnt)
1534 gimple def_stmt = SSA_NAME_DEF_STMT (vdef);
1537 && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef)))
1540 if (gimple_nop_p (def_stmt))
1542 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1546 *visited = BITMAP_ALLOC (NULL);
1547 for (i = 0; i < gimple_phi_num_args (def_stmt); ++i)
1548 cnt += walk_aliased_vdefs_1 (ref, gimple_phi_arg_def (def_stmt, i),
1549 walker, data, visited, 0);
1553 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1556 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1557 && (*walker) (ref, vdef, data))
1560 vdef = gimple_vuse (def_stmt);
1566 walk_aliased_vdefs (ao_ref *ref, tree vdef,
1567 bool (*walker)(ao_ref *, tree, void *), void *data,
1570 bitmap local_visited = NULL;
1573 timevar_push (TV_ALIAS_STMT_WALK);
1575 ret = walk_aliased_vdefs_1 (ref, vdef, walker, data,
1576 visited ? visited : &local_visited, 0);
1578 BITMAP_FREE (local_visited);
1580 timevar_pop (TV_ALIAS_STMT_WALK);