1 /* Alias analysis for trees.
2 Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010
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"
28 #include "basic-block.h"
31 #include "langhooks.h"
35 #include "tree-pretty-print.h"
36 #include "tree-dump.h"
38 #include "tree-flow.h"
39 #include "tree-inline.h"
40 #include "tree-pass.h"
43 #include "ipa-type-escape.h"
47 #include "pointer-set.h"
48 #include "alloc-pool.h"
49 #include "tree-ssa-alias.h"
51 /* Broad overview of how alias analysis on gimple works:
53 Statements clobbering or using memory are linked through the
54 virtual operand factored use-def chain. The virtual operand
55 is unique per function, its symbol is accessible via gimple_vop (cfun).
56 Virtual operands are used for efficiently walking memory statements
57 in the gimple IL and are useful for things like value-numbering as
58 a generation count for memory references.
60 SSA_NAME pointers may have associated points-to information
61 accessible via the SSA_NAME_PTR_INFO macro. Flow-insensitive
62 points-to information is (re-)computed by the TODO_rebuild_alias
63 pass manager todo. Points-to information is also used for more
64 precise tracking of call-clobbered and call-used variables and
65 related disambiguations.
67 This file contains functions for disambiguating memory references,
68 the so called alias-oracle and tools for walking of the gimple IL.
70 The main alias-oracle entry-points are
72 bool stmt_may_clobber_ref_p (gimple, tree)
74 This function queries if a statement may invalidate (parts of)
75 the memory designated by the reference tree argument.
77 bool ref_maybe_used_by_stmt_p (gimple, tree)
79 This function queries if a statement may need (parts of) the
80 memory designated by the reference tree argument.
82 There are variants of these functions that only handle the call
83 part of a statement, call_may_clobber_ref_p and ref_maybe_used_by_call_p.
84 Note that these do not disambiguate against a possible call lhs.
86 bool refs_may_alias_p (tree, tree)
88 This function tries to disambiguate two reference trees.
90 bool ptr_deref_may_alias_global_p (tree)
92 This function queries if dereferencing a pointer variable may
95 More low-level disambiguators are available and documented in
96 this file. Low-level disambiguators dealing with points-to
97 information are in tree-ssa-structalias.c. */
100 /* Query statistics for the different low-level disambiguators.
101 A high-level query may trigger multiple of them. */
104 unsigned HOST_WIDE_INT refs_may_alias_p_may_alias;
105 unsigned HOST_WIDE_INT refs_may_alias_p_no_alias;
106 unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_may_alias;
107 unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_no_alias;
108 unsigned HOST_WIDE_INT call_may_clobber_ref_p_may_alias;
109 unsigned HOST_WIDE_INT call_may_clobber_ref_p_no_alias;
113 dump_alias_stats (FILE *s)
115 fprintf (s, "\nAlias oracle query stats:\n");
116 fprintf (s, " refs_may_alias_p: "
117 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
118 HOST_WIDE_INT_PRINT_DEC" queries\n",
119 alias_stats.refs_may_alias_p_no_alias,
120 alias_stats.refs_may_alias_p_no_alias
121 + alias_stats.refs_may_alias_p_may_alias);
122 fprintf (s, " ref_maybe_used_by_call_p: "
123 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
124 HOST_WIDE_INT_PRINT_DEC" queries\n",
125 alias_stats.ref_maybe_used_by_call_p_no_alias,
126 alias_stats.refs_may_alias_p_no_alias
127 + alias_stats.ref_maybe_used_by_call_p_may_alias);
128 fprintf (s, " call_may_clobber_ref_p: "
129 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
130 HOST_WIDE_INT_PRINT_DEC" queries\n",
131 alias_stats.call_may_clobber_ref_p_no_alias,
132 alias_stats.call_may_clobber_ref_p_no_alias
133 + alias_stats.call_may_clobber_ref_p_may_alias);
137 /* Return true, if dereferencing PTR may alias with a global variable. */
140 ptr_deref_may_alias_global_p (tree ptr)
142 struct ptr_info_def *pi;
144 /* If we end up with a pointer constant here that may point
146 if (TREE_CODE (ptr) != SSA_NAME)
149 pi = SSA_NAME_PTR_INFO (ptr);
151 /* If we do not have points-to information for this variable,
156 /* ??? This does not use TBAA to prune globals ptr may not access. */
157 return pt_solution_includes_global (&pi->pt);
160 /* Return true if dereferencing PTR may alias DECL.
161 The caller is responsible for applying TBAA to see if PTR
162 may access DECL at all. */
165 ptr_deref_may_alias_decl_p (tree ptr, tree decl)
167 struct ptr_info_def *pi;
169 gcc_assert ((TREE_CODE (ptr) == SSA_NAME
170 || TREE_CODE (ptr) == ADDR_EXPR
171 || TREE_CODE (ptr) == INTEGER_CST)
172 && (TREE_CODE (decl) == VAR_DECL
173 || TREE_CODE (decl) == PARM_DECL
174 || TREE_CODE (decl) == RESULT_DECL));
176 /* Non-aliased variables can not be pointed to. */
177 if (!may_be_aliased (decl))
180 /* ADDR_EXPR pointers either just offset another pointer or directly
181 specify the pointed-to set. */
182 if (TREE_CODE (ptr) == ADDR_EXPR)
184 tree base = get_base_address (TREE_OPERAND (ptr, 0));
186 && (INDIRECT_REF_P (base)
187 || TREE_CODE (base) == MEM_REF))
188 ptr = TREE_OPERAND (base, 0);
193 && CONSTANT_CLASS_P (base))
199 /* We can end up with dereferencing constant pointers.
200 Just bail out in this case. */
201 if (TREE_CODE (ptr) == INTEGER_CST)
204 /* If we do not have useful points-to information for this pointer
205 we cannot disambiguate anything else. */
206 pi = SSA_NAME_PTR_INFO (ptr);
210 /* If the decl can be used as a restrict tag and we have a restrict
211 pointer and that pointers points-to set doesn't contain this decl
212 then they can't alias. */
213 if (DECL_RESTRICTED_P (decl)
214 && TYPE_RESTRICT (TREE_TYPE (ptr))
215 && pi->pt.vars_contains_restrict)
216 return bitmap_bit_p (pi->pt.vars, DECL_PT_UID (decl));
218 return pt_solution_includes (&pi->pt, decl);
221 /* Return true if dereferenced PTR1 and PTR2 may alias.
222 The caller is responsible for applying TBAA to see if accesses
223 through PTR1 and PTR2 may conflict at all. */
226 ptr_derefs_may_alias_p (tree ptr1, tree ptr2)
228 struct ptr_info_def *pi1, *pi2;
230 gcc_assert ((TREE_CODE (ptr1) == SSA_NAME
231 || TREE_CODE (ptr1) == ADDR_EXPR
232 || TREE_CODE (ptr1) == INTEGER_CST)
233 && (TREE_CODE (ptr2) == SSA_NAME
234 || TREE_CODE (ptr2) == ADDR_EXPR
235 || TREE_CODE (ptr2) == INTEGER_CST));
237 /* ADDR_EXPR pointers either just offset another pointer or directly
238 specify the pointed-to set. */
239 if (TREE_CODE (ptr1) == ADDR_EXPR)
241 tree base = get_base_address (TREE_OPERAND (ptr1, 0));
243 && (INDIRECT_REF_P (base)
244 || TREE_CODE (base) == MEM_REF))
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 || TREE_CODE (base) == MEM_REF))
258 ptr2 = TREE_OPERAND (base, 0);
261 return ptr_deref_may_alias_decl_p (ptr1, base);
266 /* We can end up with dereferencing constant pointers.
267 Just bail out in this case. */
268 if (TREE_CODE (ptr1) == INTEGER_CST
269 || TREE_CODE (ptr2) == INTEGER_CST)
272 /* We may end up with two empty points-to solutions for two same pointers.
273 In this case we still want to say both pointers alias, so shortcut
278 /* If we do not have useful points-to information for either pointer
279 we cannot disambiguate anything else. */
280 pi1 = SSA_NAME_PTR_INFO (ptr1);
281 pi2 = SSA_NAME_PTR_INFO (ptr2);
285 /* If both pointers are restrict-qualified try to disambiguate
286 with restrict information. */
287 if (TYPE_RESTRICT (TREE_TYPE (ptr1))
288 && TYPE_RESTRICT (TREE_TYPE (ptr2))
289 && !pt_solutions_same_restrict_base (&pi1->pt, &pi2->pt))
292 /* ??? This does not use TBAA to prune decls from the intersection
293 that not both pointers may access. */
294 return pt_solutions_intersect (&pi1->pt, &pi2->pt);
297 /* Return true if dereferencing PTR may alias *REF.
298 The caller is responsible for applying TBAA to see if PTR
299 may access *REF at all. */
302 ptr_deref_may_alias_ref_p_1 (tree ptr, ao_ref *ref)
304 tree base = ao_ref_base (ref);
306 if (INDIRECT_REF_P (base)
307 || TREE_CODE (base) == MEM_REF)
308 return ptr_derefs_may_alias_p (ptr, TREE_OPERAND (base, 0));
309 else if (SSA_VAR_P (base))
310 return ptr_deref_may_alias_decl_p (ptr, base);
316 /* Dump alias information on FILE. */
319 dump_alias_info (FILE *file)
323 = lang_hooks.decl_printable_name (current_function_decl, 2);
324 referenced_var_iterator rvi;
327 fprintf (file, "\n\nAlias information for %s\n\n", funcname);
329 fprintf (file, "Aliased symbols\n\n");
331 FOR_EACH_REFERENCED_VAR (var, rvi)
333 if (may_be_aliased (var))
334 dump_variable (file, var);
337 fprintf (file, "\nCall clobber information\n");
339 fprintf (file, "\nESCAPED");
340 dump_points_to_solution (file, &cfun->gimple_df->escaped);
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 /* Dump the points-to set *PT into FILE. */
374 dump_points_to_solution (FILE *file, struct pt_solution *pt)
377 fprintf (file, ", points-to anything");
380 fprintf (file, ", points-to non-local");
383 fprintf (file, ", points-to escaped");
386 fprintf (file, ", points-to unit escaped");
389 fprintf (file, ", points-to NULL");
393 fprintf (file, ", points-to vars: ");
394 dump_decl_set (file, pt->vars);
395 if (pt->vars_contains_global)
396 fprintf (file, " (includes global vars)");
397 if (pt->vars_contains_restrict)
398 fprintf (file, " (includes restrict tags)");
402 /* Dump points-to information for SSA_NAME PTR into FILE. */
405 dump_points_to_info_for (FILE *file, tree ptr)
407 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
409 print_generic_expr (file, ptr, dump_flags);
412 dump_points_to_solution (file, &pi->pt);
414 fprintf (file, ", points-to anything");
416 fprintf (file, "\n");
420 /* Dump points-to information for VAR into stderr. */
423 debug_points_to_info_for (tree var)
425 dump_points_to_info_for (stderr, var);
429 /* Initializes the alias-oracle reference representation *R from REF. */
432 ao_ref_init (ao_ref *r, tree ref)
439 r->ref_alias_set = -1;
440 r->base_alias_set = -1;
443 /* Returns the base object of the memory reference *REF. */
446 ao_ref_base (ao_ref *ref)
450 ref->base = get_ref_base_and_extent (ref->ref, &ref->offset, &ref->size,
455 /* Returns the base object alias set of the memory reference *REF. */
457 static alias_set_type
458 ao_ref_base_alias_set (ao_ref *ref)
461 if (ref->base_alias_set != -1)
462 return ref->base_alias_set;
466 while (handled_component_p (base_ref))
467 base_ref = TREE_OPERAND (base_ref, 0);
468 ref->base_alias_set = get_alias_set (base_ref);
469 return ref->base_alias_set;
472 /* Returns the reference alias set of the memory reference *REF. */
475 ao_ref_alias_set (ao_ref *ref)
477 if (ref->ref_alias_set != -1)
478 return ref->ref_alias_set;
479 ref->ref_alias_set = get_alias_set (ref->ref);
480 return ref->ref_alias_set;
483 /* Init an alias-oracle reference representation from a gimple pointer
484 PTR and a gimple size SIZE in bytes. If SIZE is NULL_TREE the the
485 size is assumed to be unknown. The access is assumed to be only
486 to or after of the pointer target, not before it. */
489 ao_ref_init_from_ptr_and_size (ao_ref *ref, tree ptr, tree size)
491 HOST_WIDE_INT t1, t2;
492 ref->ref = NULL_TREE;
493 if (TREE_CODE (ptr) == ADDR_EXPR)
494 ref->base = get_ref_base_and_extent (TREE_OPERAND (ptr, 0),
495 &ref->offset, &t1, &t2);
498 ref->base = build2 (MEM_REF, char_type_node,
499 ptr, null_pointer_node);
503 && host_integerp (size, 0)
504 && TREE_INT_CST_LOW (size) * 8 / 8 == TREE_INT_CST_LOW (size))
505 ref->max_size = ref->size = TREE_INT_CST_LOW (size) * 8;
507 ref->max_size = ref->size = -1;
508 ref->ref_alias_set = 0;
509 ref->base_alias_set = 0;
512 /* Return 1 if TYPE1 and TYPE2 are to be considered equivalent for the
513 purpose of TBAA. Return 0 if they are distinct and -1 if we cannot
517 same_type_for_tbaa (tree type1, tree type2)
519 type1 = TYPE_MAIN_VARIANT (type1);
520 type2 = TYPE_MAIN_VARIANT (type2);
522 /* If we would have to do structural comparison bail out. */
523 if (TYPE_STRUCTURAL_EQUALITY_P (type1)
524 || TYPE_STRUCTURAL_EQUALITY_P (type2))
527 /* Compare the canonical types. */
528 if (TYPE_CANONICAL (type1) == TYPE_CANONICAL (type2))
531 /* ??? Array types are not properly unified in all cases as we have
532 spurious changes in the index types for example. Removing this
533 causes all sorts of problems with the Fortran frontend. */
534 if (TREE_CODE (type1) == ARRAY_TYPE
535 && TREE_CODE (type2) == ARRAY_TYPE)
538 /* ??? In Ada, an lvalue of an unconstrained type can be used to access an
539 object of one of its constrained subtypes, e.g. when a function with an
540 unconstrained parameter passed by reference is called on an object and
541 inlined. But, even in the case of a fixed size, type and subtypes are
542 not equivalent enough as to share the same TYPE_CANONICAL, since this
543 would mean that conversions between them are useless, whereas they are
544 not (e.g. type and subtypes can have different modes). So, in the end,
545 they are only guaranteed to have the same alias set. */
546 if (get_alias_set (type1) == get_alias_set (type2))
549 /* The types are known to be not equal. */
553 /* Determine if the two component references REF1 and REF2 which are
554 based on access types TYPE1 and TYPE2 and of which at least one is based
555 on an indirect reference may alias. REF2 is the only one that can
556 be a decl in which case REF2_IS_DECL is true.
557 REF1_ALIAS_SET, BASE1_ALIAS_SET, REF2_ALIAS_SET and BASE2_ALIAS_SET
558 are the respective alias sets. */
561 aliasing_component_refs_p (tree ref1, tree type1,
562 alias_set_type ref1_alias_set,
563 alias_set_type base1_alias_set,
564 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
565 tree ref2, tree type2,
566 alias_set_type ref2_alias_set,
567 alias_set_type base2_alias_set,
568 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
571 /* If one reference is a component references through pointers try to find a
572 common base and apply offset based disambiguation. This handles
574 struct A { int i; int j; } *q;
575 struct B { struct A a; int k; } *p;
576 disambiguating q->i and p->a.j. */
580 /* Now search for the type1 in the access path of ref2. This
581 would be a common base for doing offset based disambiguation on. */
583 while (handled_component_p (*refp)
584 && same_type_for_tbaa (TREE_TYPE (*refp), type1) == 0)
585 refp = &TREE_OPERAND (*refp, 0);
586 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type1);
587 /* If we couldn't compare types we have to bail out. */
590 else if (same_p == 1)
592 HOST_WIDE_INT offadj, sztmp, msztmp;
593 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
595 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
597 /* If we didn't find a common base, try the other way around. */
599 while (handled_component_p (*refp)
600 && same_type_for_tbaa (TREE_TYPE (*refp), type2) == 0)
601 refp = &TREE_OPERAND (*refp, 0);
602 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type2);
603 /* If we couldn't compare types we have to bail out. */
606 else if (same_p == 1)
608 HOST_WIDE_INT offadj, sztmp, msztmp;
609 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
611 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
614 /* If we have two type access paths B1.path1 and B2.path2 they may
615 only alias if either B1 is in B2.path2 or B2 is in B1.path1.
616 But we can still have a path that goes B1.path1...B2.path2 with
617 a part that we do not see. So we can only disambiguate now
618 if there is no B2 in the tail of path1 and no B1 on the
620 if (base1_alias_set == ref2_alias_set
621 || alias_set_subset_of (base1_alias_set, ref2_alias_set))
623 /* If this is ptr vs. decl then we know there is no ptr ... decl path. */
625 return (base2_alias_set == ref1_alias_set
626 || alias_set_subset_of (base2_alias_set, ref1_alias_set));
630 /* Return true if two memory references based on the variables BASE1
631 and BASE2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
632 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. */
635 decl_refs_may_alias_p (tree base1,
636 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
638 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
640 gcc_assert (SSA_VAR_P (base1) && SSA_VAR_P (base2));
642 /* If both references are based on different variables, they cannot alias. */
646 /* If both references are based on the same variable, they cannot alias if
647 the accesses do not overlap. */
648 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
651 /* Return true if an indirect reference based on *PTR1 constrained
652 to [OFFSET1, OFFSET1 + MAX_SIZE1) may alias a variable based on BASE2
653 constrained to [OFFSET2, OFFSET2 + MAX_SIZE2). *PTR1 and BASE2 have
654 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
655 in which case they are computed on-demand. REF1 and REF2
656 if non-NULL are the complete memory reference trees. */
659 indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
660 HOST_WIDE_INT offset1,
661 HOST_WIDE_INT max_size1 ATTRIBUTE_UNUSED,
662 alias_set_type ref1_alias_set,
663 alias_set_type base1_alias_set,
664 tree ref2 ATTRIBUTE_UNUSED, tree base2,
665 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
666 alias_set_type ref2_alias_set,
667 alias_set_type base2_alias_set, bool tbaa_p)
669 tree ptr1 = TREE_OPERAND (base1, 0);
671 HOST_WIDE_INT offset1p = offset1, offset2p = offset2;
673 /* The offset embedded in MEM_REFs can be negative. Bias them
674 so that the resulting offset adjustment is positive. */
675 if (TREE_CODE (base1) == MEM_REF)
677 double_int moff = mem_ref_offset (base1);
678 moff = double_int_lshift (moff,
680 ? 3 : exact_log2 (BITS_PER_UNIT),
681 HOST_BITS_PER_DOUBLE_INT, true);
682 if (double_int_negative_p (moff))
683 offset2p += double_int_neg (moff).low;
685 offset1p += moff.low;
688 /* If only one reference is based on a variable, they cannot alias if
689 the pointer access is beyond the extent of the variable access.
690 (the pointer base cannot validly point to an offset less than zero
692 They also cannot alias if the pointer may not point to the decl. */
693 if (!ranges_overlap_p (MAX (0, offset1p), -1, offset2p, max_size2))
695 if (!ptr_deref_may_alias_decl_p (ptr1, base2))
698 /* Disambiguations that rely on strict aliasing rules follow. */
699 if (!flag_strict_aliasing || !tbaa_p)
702 if (TREE_CODE (base1) == MEM_REF)
703 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
705 ptrtype1 = TREE_TYPE (ptr1);
707 /* If the alias set for a pointer access is zero all bets are off. */
708 if (base1_alias_set == -1)
709 base1_alias_set = get_deref_alias_set (ptrtype1);
710 if (base1_alias_set == 0)
712 if (base2_alias_set == -1)
713 base2_alias_set = get_alias_set (base2);
715 /* If both references are through the same type, they do not alias
716 if the accesses do not overlap. This does extra disambiguation
717 for mixed/pointer accesses but requires strict aliasing.
718 For MEM_REFs we require that the component-ref offset we computed
719 is relative to the start of the type which we ensure by
720 comparing rvalue and access type and disregarding the constant
722 if ((TREE_CODE (base1) != MEM_REF
723 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
724 && same_type_for_tbaa (TREE_TYPE (ptrtype1), TREE_TYPE (base2)) == 1)
725 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
727 /* When we are trying to disambiguate an access with a pointer dereference
728 as base versus one with a decl as base we can use both the size
729 of the decl and its dynamic type for extra disambiguation.
730 ??? We do not know anything about the dynamic type of the decl
731 other than that its alias-set contains base2_alias_set as a subset
732 which does not help us here. */
733 /* As we know nothing useful about the dynamic type of the decl just
734 use the usual conflict check rather than a subset test.
735 ??? We could introduce -fvery-strict-aliasing when the language
736 does not allow decls to have a dynamic type that differs from their
737 static type. Then we can check
738 !alias_set_subset_of (base1_alias_set, base2_alias_set) instead. */
739 if (base1_alias_set != base2_alias_set
740 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
742 /* If the size of the access relevant for TBAA through the pointer
743 is bigger than the size of the decl we can't possibly access the
744 decl via that pointer. */
745 if (DECL_SIZE (base2) && COMPLETE_TYPE_P (TREE_TYPE (ptrtype1))
746 && TREE_CODE (DECL_SIZE (base2)) == INTEGER_CST
747 && TREE_CODE (TYPE_SIZE (TREE_TYPE (ptrtype1))) == INTEGER_CST
748 /* ??? This in turn may run afoul when a decl of type T which is
749 a member of union type U is accessed through a pointer to
750 type U and sizeof T is smaller than sizeof U. */
751 && TREE_CODE (TREE_TYPE (ptrtype1)) != UNION_TYPE
752 && TREE_CODE (TREE_TYPE (ptrtype1)) != QUAL_UNION_TYPE
753 && tree_int_cst_lt (DECL_SIZE (base2), TYPE_SIZE (TREE_TYPE (ptrtype1))))
756 /* Do access-path based disambiguation. */
758 && handled_component_p (ref1)
759 && handled_component_p (ref2)
760 && (TREE_CODE (base1) != MEM_REF
761 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1))
762 return aliasing_component_refs_p (ref1, TREE_TYPE (ptrtype1),
763 ref1_alias_set, base1_alias_set,
765 ref2, TREE_TYPE (base2),
766 ref2_alias_set, base2_alias_set,
767 offset2, max_size2, true);
772 /* Return true if two indirect references based on *PTR1
773 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
774 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have
775 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
776 in which case they are computed on-demand. REF1 and REF2
777 if non-NULL are the complete memory reference trees. */
780 indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
781 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
782 alias_set_type ref1_alias_set,
783 alias_set_type base1_alias_set,
784 tree ref2 ATTRIBUTE_UNUSED, tree base2,
785 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
786 alias_set_type ref2_alias_set,
787 alias_set_type base2_alias_set, bool tbaa_p)
789 tree ptr1 = TREE_OPERAND (base1, 0);
790 tree ptr2 = TREE_OPERAND (base2, 0);
791 tree ptrtype1, ptrtype2;
793 /* If both bases are based on pointers they cannot alias if they may not
794 point to the same memory object or if they point to the same object
795 and the accesses do not overlap. */
796 if ((!cfun || gimple_in_ssa_p (cfun))
797 && operand_equal_p (ptr1, ptr2, 0))
799 /* The offset embedded in MEM_REFs can be negative. Bias them
800 so that the resulting offset adjustment is positive. */
801 if (TREE_CODE (base1) == MEM_REF)
803 double_int moff = mem_ref_offset (base1);
804 moff = double_int_lshift (moff,
806 ? 3 : exact_log2 (BITS_PER_UNIT),
807 HOST_BITS_PER_DOUBLE_INT, true);
808 if (double_int_negative_p (moff))
809 offset2 += double_int_neg (moff).low;
813 if (TREE_CODE (base2) == MEM_REF)
815 double_int moff = mem_ref_offset (base2);
816 moff = double_int_lshift (moff,
818 ? 3 : exact_log2 (BITS_PER_UNIT),
819 HOST_BITS_PER_DOUBLE_INT, true);
820 if (double_int_negative_p (moff))
821 offset1 += double_int_neg (moff).low;
825 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
827 if (!ptr_derefs_may_alias_p (ptr1, ptr2))
830 /* Disambiguations that rely on strict aliasing rules follow. */
831 if (!flag_strict_aliasing || !tbaa_p)
834 if (TREE_CODE (base1) == MEM_REF)
835 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
837 ptrtype1 = TREE_TYPE (ptr1);
838 if (TREE_CODE (base2) == MEM_REF)
839 ptrtype2 = TREE_TYPE (TREE_OPERAND (base2, 1));
841 ptrtype2 = TREE_TYPE (ptr2);
843 /* If the alias set for a pointer access is zero all bets are off. */
844 if (base1_alias_set == -1)
845 base1_alias_set = get_deref_alias_set (ptrtype1);
846 if (base1_alias_set == 0)
848 if (base2_alias_set == -1)
849 base2_alias_set = get_deref_alias_set (ptrtype2);
850 if (base2_alias_set == 0)
853 /* If both references are through the same type, they do not alias
854 if the accesses do not overlap. This does extra disambiguation
855 for mixed/pointer accesses but requires strict aliasing. */
856 if ((TREE_CODE (base1) != MEM_REF
857 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
858 && (TREE_CODE (base2) != MEM_REF
859 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1)
860 && same_type_for_tbaa (TREE_TYPE (ptrtype1),
861 TREE_TYPE (ptrtype2)) == 1)
862 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
864 /* Do type-based disambiguation. */
865 if (base1_alias_set != base2_alias_set
866 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
869 /* Do access-path based disambiguation. */
871 && handled_component_p (ref1)
872 && handled_component_p (ref2)
873 && (TREE_CODE (base1) != MEM_REF
874 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
875 && (TREE_CODE (base2) != MEM_REF
876 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1))
877 return aliasing_component_refs_p (ref1, TREE_TYPE (ptrtype1),
878 ref1_alias_set, base1_alias_set,
880 ref2, TREE_TYPE (ptrtype2),
881 ref2_alias_set, base2_alias_set,
882 offset2, max_size2, false);
887 /* Return true, if the two memory references REF1 and REF2 may alias. */
890 refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
893 HOST_WIDE_INT offset1 = 0, offset2 = 0;
894 HOST_WIDE_INT max_size1 = -1, max_size2 = -1;
895 bool var1_p, var2_p, ind1_p, ind2_p;
897 gcc_checking_assert ((!ref1->ref
898 || TREE_CODE (ref1->ref) == SSA_NAME
899 || DECL_P (ref1->ref)
900 || handled_component_p (ref1->ref)
901 || INDIRECT_REF_P (ref1->ref)
902 || TREE_CODE (ref1->ref) == MEM_REF
903 || TREE_CODE (ref1->ref) == TARGET_MEM_REF)
905 || TREE_CODE (ref2->ref) == SSA_NAME
906 || DECL_P (ref2->ref)
907 || handled_component_p (ref2->ref)
908 || INDIRECT_REF_P (ref2->ref)
909 || TREE_CODE (ref2->ref) == MEM_REF
910 || TREE_CODE (ref2->ref) == TARGET_MEM_REF));
912 /* Decompose the references into their base objects and the access. */
913 base1 = ao_ref_base (ref1);
914 offset1 = ref1->offset;
915 max_size1 = ref1->max_size;
916 base2 = ao_ref_base (ref2);
917 offset2 = ref2->offset;
918 max_size2 = ref2->max_size;
920 /* We can end up with registers or constants as bases for example from
921 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
922 which is seen as a struct copy. */
923 if (TREE_CODE (base1) == SSA_NAME
924 || TREE_CODE (base2) == SSA_NAME
925 || TREE_CODE (base1) == CONST_DECL
926 || TREE_CODE (base2) == CONST_DECL
927 || is_gimple_min_invariant (base1)
928 || is_gimple_min_invariant (base2))
931 /* We can end up refering to code via function and label decls.
932 As we likely do not properly track code aliases conservatively
934 if (TREE_CODE (base1) == FUNCTION_DECL
935 || TREE_CODE (base2) == FUNCTION_DECL
936 || TREE_CODE (base1) == LABEL_DECL
937 || TREE_CODE (base2) == LABEL_DECL)
940 /* Defer to simple offset based disambiguation if we have
941 references based on two decls. Do this before defering to
942 TBAA to handle must-alias cases in conformance with the
943 GCC extension of allowing type-punning through unions. */
944 var1_p = SSA_VAR_P (base1);
945 var2_p = SSA_VAR_P (base2);
946 if (var1_p && var2_p)
947 return decl_refs_may_alias_p (base1, offset1, max_size1,
948 base2, offset2, max_size2);
950 ind1_p = INDIRECT_REF_P (base1) || (TREE_CODE (base1) == MEM_REF);
951 ind2_p = INDIRECT_REF_P (base2) || (TREE_CODE (base2) == MEM_REF);
953 /* Canonicalize the pointer-vs-decl case. */
954 if (ind1_p && var2_p)
959 tmp1 = offset1; offset1 = offset2; offset2 = tmp1;
960 tmp1 = max_size1; max_size1 = max_size2; max_size2 = tmp1;
961 tmp2 = base1; base1 = base2; base2 = tmp2;
962 tmp3 = ref1; ref1 = ref2; ref2 = tmp3;
969 /* First defer to TBAA if possible. */
971 && flag_strict_aliasing
972 && !alias_sets_conflict_p (ao_ref_alias_set (ref1),
973 ao_ref_alias_set (ref2)))
976 /* If one reference is a TARGET_MEM_REF weird things are allowed. Still
977 TBAA disambiguation based on the access type is possible, so bail
978 out only after that check. */
979 if ((ref1->ref && TREE_CODE (ref1->ref) == TARGET_MEM_REF)
980 || (ref2->ref && TREE_CODE (ref2->ref) == TARGET_MEM_REF))
983 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */
984 if (var1_p && ind2_p)
985 return indirect_ref_may_alias_decl_p (ref2->ref, base2,
987 ao_ref_alias_set (ref2), -1,
990 ao_ref_alias_set (ref1),
991 ao_ref_base_alias_set (ref1),
993 else if (ind1_p && ind2_p)
994 return indirect_refs_may_alias_p (ref1->ref, base1,
996 ao_ref_alias_set (ref1), -1,
999 ao_ref_alias_set (ref2), -1,
1006 refs_may_alias_p (tree ref1, tree ref2)
1010 ao_ref_init (&r1, ref1);
1011 ao_ref_init (&r2, ref2);
1012 res = refs_may_alias_p_1 (&r1, &r2, true);
1014 ++alias_stats.refs_may_alias_p_may_alias;
1016 ++alias_stats.refs_may_alias_p_no_alias;
1020 /* Returns true if there is a anti-dependence for the STORE that
1021 executes after the LOAD. */
1024 refs_anti_dependent_p (tree load, tree store)
1027 ao_ref_init (&r1, load);
1028 ao_ref_init (&r2, store);
1029 return refs_may_alias_p_1 (&r1, &r2, false);
1032 /* Returns true if there is a output dependence for the stores
1033 STORE1 and STORE2. */
1036 refs_output_dependent_p (tree store1, tree store2)
1039 ao_ref_init (&r1, store1);
1040 ao_ref_init (&r2, store2);
1041 return refs_may_alias_p_1 (&r1, &r2, false);
1044 /* If the call CALL may use the memory reference REF return true,
1045 otherwise return false. */
1048 ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
1052 int flags = gimple_call_flags (call);
1054 /* Const functions without a static chain do not implicitly use memory. */
1055 if (!gimple_call_chain (call)
1056 && (flags & (ECF_CONST|ECF_NOVOPS)))
1059 base = ao_ref_base (ref);
1063 /* If the reference is based on a decl that is not aliased the call
1064 cannot possibly use it. */
1066 && !may_be_aliased (base)
1067 /* But local statics can be used through recursion. */
1068 && !is_global_var (base))
1071 callee = gimple_call_fndecl (call);
1073 /* Handle those builtin functions explicitly that do not act as
1074 escape points. See tree-ssa-structalias.c:find_func_aliases
1075 for the list of builtins we might need to handle here. */
1076 if (callee != NULL_TREE
1077 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1078 switch (DECL_FUNCTION_CODE (callee))
1080 /* All the following functions clobber memory pointed to by
1081 their first argument. */
1082 case BUILT_IN_STRCPY:
1083 case BUILT_IN_STRNCPY:
1084 case BUILT_IN_MEMCPY:
1085 case BUILT_IN_MEMMOVE:
1086 case BUILT_IN_MEMPCPY:
1087 case BUILT_IN_STPCPY:
1088 case BUILT_IN_STPNCPY:
1089 case BUILT_IN_STRCAT:
1090 case BUILT_IN_STRNCAT:
1093 tree size = NULL_TREE;
1094 if (gimple_call_num_args (call) == 3)
1095 size = gimple_call_arg (call, 2);
1096 ao_ref_init_from_ptr_and_size (&dref,
1097 gimple_call_arg (call, 1),
1099 return refs_may_alias_p_1 (&dref, ref, false);
1101 case BUILT_IN_BCOPY:
1104 tree size = gimple_call_arg (call, 2);
1105 ao_ref_init_from_ptr_and_size (&dref,
1106 gimple_call_arg (call, 0),
1108 return refs_may_alias_p_1 (&dref, ref, false);
1110 /* The following builtins do not read from memory. */
1112 case BUILT_IN_MALLOC:
1113 case BUILT_IN_CALLOC:
1114 case BUILT_IN_MEMSET:
1115 case BUILT_IN_FREXP:
1116 case BUILT_IN_FREXPF:
1117 case BUILT_IN_FREXPL:
1118 case BUILT_IN_GAMMA_R:
1119 case BUILT_IN_GAMMAF_R:
1120 case BUILT_IN_GAMMAL_R:
1121 case BUILT_IN_LGAMMA_R:
1122 case BUILT_IN_LGAMMAF_R:
1123 case BUILT_IN_LGAMMAL_R:
1125 case BUILT_IN_MODFF:
1126 case BUILT_IN_MODFL:
1127 case BUILT_IN_REMQUO:
1128 case BUILT_IN_REMQUOF:
1129 case BUILT_IN_REMQUOL:
1130 case BUILT_IN_SINCOS:
1131 case BUILT_IN_SINCOSF:
1132 case BUILT_IN_SINCOSL:
1136 /* Fallthru to general call handling. */;
1139 /* Check if base is a global static variable that is not read
1141 if (TREE_CODE (base) == VAR_DECL
1142 && TREE_STATIC (base))
1146 if (callee != NULL_TREE
1148 = ipa_reference_get_not_read_global (cgraph_node (callee)))
1149 && bitmap_bit_p (not_read, DECL_UID (base)))
1153 /* Check if the base variable is call-used. */
1156 if (pt_solution_includes (gimple_call_use_set (call), base))
1159 else if ((INDIRECT_REF_P (base)
1160 || TREE_CODE (base) == MEM_REF)
1161 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1163 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1167 if (pt_solutions_intersect (gimple_call_use_set (call), &pi->pt))
1173 /* Inspect call arguments for passed-by-value aliases. */
1175 for (i = 0; i < gimple_call_num_args (call); ++i)
1177 tree op = gimple_call_arg (call, i);
1178 int flags = gimple_call_arg_flags (call, i);
1180 if (flags & EAF_UNUSED)
1183 if (TREE_CODE (op) == WITH_SIZE_EXPR)
1184 op = TREE_OPERAND (op, 0);
1186 if (TREE_CODE (op) != SSA_NAME
1187 && !is_gimple_min_invariant (op))
1190 ao_ref_init (&r, op);
1191 if (refs_may_alias_p_1 (&r, ref, true))
1200 ref_maybe_used_by_call_p (gimple call, tree ref)
1204 ao_ref_init (&r, ref);
1205 res = ref_maybe_used_by_call_p_1 (call, &r);
1207 ++alias_stats.ref_maybe_used_by_call_p_may_alias;
1209 ++alias_stats.ref_maybe_used_by_call_p_no_alias;
1214 /* If the statement STMT may use the memory reference REF return
1215 true, otherwise return false. */
1218 ref_maybe_used_by_stmt_p (gimple stmt, tree ref)
1220 if (is_gimple_assign (stmt))
1224 /* All memory assign statements are single. */
1225 if (!gimple_assign_single_p (stmt))
1228 rhs = gimple_assign_rhs1 (stmt);
1229 if (is_gimple_reg (rhs)
1230 || is_gimple_min_invariant (rhs)
1231 || gimple_assign_rhs_code (stmt) == CONSTRUCTOR)
1234 return refs_may_alias_p (rhs, ref);
1236 else if (is_gimple_call (stmt))
1237 return ref_maybe_used_by_call_p (stmt, ref);
1242 /* If the call in statement CALL may clobber the memory reference REF
1243 return true, otherwise return false. */
1246 call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
1251 /* If the call is pure or const it cannot clobber anything. */
1252 if (gimple_call_flags (call)
1253 & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS))
1256 base = ao_ref_base (ref);
1260 if (TREE_CODE (base) == SSA_NAME
1261 || CONSTANT_CLASS_P (base))
1264 /* If the reference is based on a decl that is not aliased the call
1265 cannot possibly clobber it. */
1267 && !may_be_aliased (base)
1268 /* But local non-readonly statics can be modified through recursion
1269 or the call may implement a threading barrier which we must
1270 treat as may-def. */
1271 && (TREE_READONLY (base)
1272 || !is_global_var (base)))
1275 callee = gimple_call_fndecl (call);
1277 /* Handle those builtin functions explicitly that do not act as
1278 escape points. See tree-ssa-structalias.c:find_func_aliases
1279 for the list of builtins we might need to handle here. */
1280 if (callee != NULL_TREE
1281 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1282 switch (DECL_FUNCTION_CODE (callee))
1284 /* All the following functions clobber memory pointed to by
1285 their first argument. */
1286 case BUILT_IN_STRCPY:
1287 case BUILT_IN_STRNCPY:
1288 case BUILT_IN_MEMCPY:
1289 case BUILT_IN_MEMMOVE:
1290 case BUILT_IN_MEMPCPY:
1291 case BUILT_IN_STPCPY:
1292 case BUILT_IN_STPNCPY:
1293 case BUILT_IN_STRCAT:
1294 case BUILT_IN_STRNCAT:
1295 case BUILT_IN_MEMSET:
1298 tree size = NULL_TREE;
1299 if (gimple_call_num_args (call) == 3)
1300 size = gimple_call_arg (call, 2);
1301 ao_ref_init_from_ptr_and_size (&dref,
1302 gimple_call_arg (call, 0),
1304 return refs_may_alias_p_1 (&dref, ref, false);
1306 case BUILT_IN_BCOPY:
1309 tree size = gimple_call_arg (call, 2);
1310 ao_ref_init_from_ptr_and_size (&dref,
1311 gimple_call_arg (call, 1),
1313 return refs_may_alias_p_1 (&dref, ref, false);
1315 /* Allocating memory does not have any side-effects apart from
1316 being the definition point for the pointer. */
1317 case BUILT_IN_MALLOC:
1318 case BUILT_IN_CALLOC:
1319 /* Unix98 specifies that errno is set on allocation failure.
1320 Until we properly can track the errno location assume it
1321 is not a local decl but external or anonymous storage in
1322 a different translation unit. Also assume it is of
1323 type int as required by the standard. */
1325 && TREE_TYPE (base) == integer_type_node)
1327 struct ptr_info_def *pi;
1329 && !TREE_STATIC (base))
1331 else if ((INDIRECT_REF_P (base)
1332 || TREE_CODE (base) == MEM_REF)
1333 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME
1334 && (pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0))))
1335 return pi->pt.anything || pi->pt.nonlocal;
1338 /* Freeing memory kills the pointed-to memory. More importantly
1339 the call has to serve as a barrier for moving loads and stores
1343 tree ptr = gimple_call_arg (call, 0);
1344 return ptr_deref_may_alias_ref_p_1 (ptr, ref);
1346 case BUILT_IN_GAMMA_R:
1347 case BUILT_IN_GAMMAF_R:
1348 case BUILT_IN_GAMMAL_R:
1349 case BUILT_IN_LGAMMA_R:
1350 case BUILT_IN_LGAMMAF_R:
1351 case BUILT_IN_LGAMMAL_R:
1353 tree out = gimple_call_arg (call, 1);
1354 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1356 if (flag_errno_math)
1360 case BUILT_IN_FREXP:
1361 case BUILT_IN_FREXPF:
1362 case BUILT_IN_FREXPL:
1364 case BUILT_IN_MODFF:
1365 case BUILT_IN_MODFL:
1367 tree out = gimple_call_arg (call, 1);
1368 return ptr_deref_may_alias_ref_p_1 (out, ref);
1370 case BUILT_IN_REMQUO:
1371 case BUILT_IN_REMQUOF:
1372 case BUILT_IN_REMQUOL:
1374 tree out = gimple_call_arg (call, 2);
1375 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1377 if (flag_errno_math)
1381 case BUILT_IN_SINCOS:
1382 case BUILT_IN_SINCOSF:
1383 case BUILT_IN_SINCOSL:
1385 tree sin = gimple_call_arg (call, 1);
1386 tree cos = gimple_call_arg (call, 2);
1387 return (ptr_deref_may_alias_ref_p_1 (sin, ref)
1388 || ptr_deref_may_alias_ref_p_1 (cos, ref));
1391 /* Fallthru to general call handling. */;
1394 /* Check if base is a global static variable that is not written
1396 if (callee != NULL_TREE
1397 && TREE_CODE (base) == VAR_DECL
1398 && TREE_STATIC (base))
1403 = ipa_reference_get_not_written_global (cgraph_node (callee)))
1404 && bitmap_bit_p (not_written, DECL_UID (base)))
1408 /* Check if the base variable is call-clobbered. */
1410 return pt_solution_includes (gimple_call_clobber_set (call), base);
1411 else if ((INDIRECT_REF_P (base)
1412 || TREE_CODE (base) == MEM_REF)
1413 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1415 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1419 return pt_solutions_intersect (gimple_call_clobber_set (call), &pi->pt);
1425 /* If the call in statement CALL may clobber the memory reference REF
1426 return true, otherwise return false. */
1429 call_may_clobber_ref_p (gimple call, tree ref)
1433 ao_ref_init (&r, ref);
1434 res = call_may_clobber_ref_p_1 (call, &r);
1436 ++alias_stats.call_may_clobber_ref_p_may_alias;
1438 ++alias_stats.call_may_clobber_ref_p_no_alias;
1443 /* If the statement STMT may clobber the memory reference REF return true,
1444 otherwise return false. */
1447 stmt_may_clobber_ref_p_1 (gimple stmt, ao_ref *ref)
1449 if (is_gimple_call (stmt))
1451 tree lhs = gimple_call_lhs (stmt);
1453 && !is_gimple_reg (lhs))
1456 ao_ref_init (&r, lhs);
1457 if (refs_may_alias_p_1 (ref, &r, true))
1461 return call_may_clobber_ref_p_1 (stmt, ref);
1463 else if (gimple_assign_single_p (stmt))
1465 tree lhs = gimple_assign_lhs (stmt);
1466 if (!is_gimple_reg (lhs))
1469 ao_ref_init (&r, gimple_assign_lhs (stmt));
1470 return refs_may_alias_p_1 (ref, &r, true);
1473 else if (gimple_code (stmt) == GIMPLE_ASM)
1480 stmt_may_clobber_ref_p (gimple stmt, tree ref)
1483 ao_ref_init (&r, ref);
1484 return stmt_may_clobber_ref_p_1 (stmt, &r);
1488 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand
1489 TARGET or a statement clobbering the memory reference REF in which
1490 case false is returned. The walk starts with VUSE, one argument of PHI. */
1493 maybe_skip_until (gimple phi, tree target, ao_ref *ref,
1494 tree vuse, bitmap *visited)
1497 *visited = BITMAP_ALLOC (NULL);
1499 bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi)));
1501 /* Walk until we hit the target. */
1502 while (vuse != target)
1504 gimple def_stmt = SSA_NAME_DEF_STMT (vuse);
1505 /* Recurse for PHI nodes. */
1506 if (gimple_code (def_stmt) == GIMPLE_PHI)
1508 /* An already visited PHI node ends the walk successfully. */
1509 if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt))))
1511 vuse = get_continuation_for_phi (def_stmt, ref, visited);
1516 /* A clobbering statement or the end of the IL ends it failing. */
1517 else if (gimple_nop_p (def_stmt)
1518 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1520 vuse = gimple_vuse (def_stmt);
1525 /* Starting from a PHI node for the virtual operand of the memory reference
1526 REF find a continuation virtual operand that allows to continue walking
1527 statements dominating PHI skipping only statements that cannot possibly
1528 clobber REF. Returns NULL_TREE if no suitable virtual operand can
1532 get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited)
1534 unsigned nargs = gimple_phi_num_args (phi);
1536 /* Through a single-argument PHI we can simply look through. */
1538 return PHI_ARG_DEF (phi, 0);
1540 /* For two arguments try to skip non-aliasing code until we hit
1541 the phi argument definition that dominates the other one. */
1544 tree arg0 = PHI_ARG_DEF (phi, 0);
1545 tree arg1 = PHI_ARG_DEF (phi, 1);
1546 gimple def0 = SSA_NAME_DEF_STMT (arg0);
1547 gimple def1 = SSA_NAME_DEF_STMT (arg1);
1552 else if (gimple_nop_p (def0)
1553 || (!gimple_nop_p (def1)
1554 && dominated_by_p (CDI_DOMINATORS,
1555 gimple_bb (def1), gimple_bb (def0))))
1557 if (maybe_skip_until (phi, arg0, ref, arg1, visited))
1560 else if (gimple_nop_p (def1)
1561 || dominated_by_p (CDI_DOMINATORS,
1562 gimple_bb (def0), gimple_bb (def1)))
1564 if (maybe_skip_until (phi, arg1, ref, arg0, visited))
1567 /* Special case of a diamond:
1569 goto (cond) ? L1 : L2
1570 L1: store1 = ... #MEM_2 = vuse(MEM_1)
1572 L2: store2 = ... #MEM_3 = vuse(MEM_1)
1573 L3: MEM_4 = PHI<MEM_2, MEM_3>
1574 We were called with the PHI at L3, MEM_2 and MEM_3 don't
1575 dominate each other, but still we can easily skip this PHI node
1576 if we recognize that the vuse MEM operand is the same for both,
1577 and that we can skip both statements (they don't clobber us).
1578 This is still linear. Don't use maybe_skip_until, that might
1579 potentially be slow. */
1580 else if ((common_vuse = gimple_vuse (def0))
1581 && common_vuse == gimple_vuse (def1))
1583 if (!stmt_may_clobber_ref_p_1 (def0, ref)
1584 && !stmt_may_clobber_ref_p_1 (def1, ref))
1592 /* Based on the memory reference REF and its virtual use VUSE call
1593 WALKER for each virtual use that is equivalent to VUSE, including VUSE
1594 itself. That is, for each virtual use for which its defining statement
1595 does not clobber REF.
1597 WALKER is called with REF, the current virtual use and DATA. If
1598 WALKER returns non-NULL the walk stops and its result is returned.
1599 At the end of a non-successful walk NULL is returned.
1601 TRANSLATE if non-NULL is called with a pointer to REF, the virtual
1602 use which definition is a statement that may clobber REF and DATA.
1603 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
1604 If TRANSLATE returns non-NULL the walk stops and its result is returned.
1605 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
1606 to adjust REF and *DATA to make that valid.
1608 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
1611 walk_non_aliased_vuses (ao_ref *ref, tree vuse,
1612 void *(*walker)(ao_ref *, tree, void *),
1613 void *(*translate)(ao_ref *, tree, void *), void *data)
1615 bitmap visited = NULL;
1618 timevar_push (TV_ALIAS_STMT_WALK);
1624 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1625 res = (*walker) (ref, vuse, data);
1629 def_stmt = SSA_NAME_DEF_STMT (vuse);
1630 if (gimple_nop_p (def_stmt))
1632 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1633 vuse = get_continuation_for_phi (def_stmt, ref, &visited);
1636 if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
1640 res = (*translate) (ref, vuse, data);
1641 /* Failed lookup and translation. */
1642 if (res == (void *)-1)
1647 /* Lookup succeeded. */
1648 else if (res != NULL)
1650 /* Translation succeeded, continue walking. */
1652 vuse = gimple_vuse (def_stmt);
1658 BITMAP_FREE (visited);
1660 timevar_pop (TV_ALIAS_STMT_WALK);
1666 /* Based on the memory reference REF call WALKER for each vdef which
1667 defining statement may clobber REF, starting with VDEF. If REF
1668 is NULL_TREE, each defining statement is visited.
1670 WALKER is called with REF, the current vdef and DATA. If WALKER
1671 returns true the walk is stopped, otherwise it continues.
1673 At PHI nodes walk_aliased_vdefs forks into one walk for reach
1674 PHI argument (but only one walk continues on merge points), the
1675 return value is true if any of the walks was successful.
1677 The function returns the number of statements walked. */
1680 walk_aliased_vdefs_1 (ao_ref *ref, tree vdef,
1681 bool (*walker)(ao_ref *, tree, void *), void *data,
1682 bitmap *visited, unsigned int cnt)
1686 gimple def_stmt = SSA_NAME_DEF_STMT (vdef);
1689 && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef)))
1692 if (gimple_nop_p (def_stmt))
1694 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1698 *visited = BITMAP_ALLOC (NULL);
1699 for (i = 0; i < gimple_phi_num_args (def_stmt); ++i)
1700 cnt += walk_aliased_vdefs_1 (ref, gimple_phi_arg_def (def_stmt, i),
1701 walker, data, visited, 0);
1705 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1708 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1709 && (*walker) (ref, vdef, data))
1712 vdef = gimple_vuse (def_stmt);
1718 walk_aliased_vdefs (ao_ref *ref, tree vdef,
1719 bool (*walker)(ao_ref *, tree, void *), void *data,
1722 bitmap local_visited = NULL;
1725 timevar_push (TV_ALIAS_STMT_WALK);
1727 ret = walk_aliased_vdefs_1 (ref, vdef, walker, data,
1728 visited ? visited : &local_visited, 0);
1730 BITMAP_FREE (local_visited);
1732 timevar_pop (TV_ALIAS_STMT_WALK);