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 (decl) == VAR_DECL
172 || TREE_CODE (decl) == PARM_DECL
173 || TREE_CODE (decl) == RESULT_DECL);
175 /* Non-aliased variables can not be pointed to. */
176 if (!may_be_aliased (decl))
179 /* ADDR_EXPR pointers either just offset another pointer or directly
180 specify the pointed-to set. */
181 if (TREE_CODE (ptr) == ADDR_EXPR)
183 tree base = get_base_address (TREE_OPERAND (ptr, 0));
185 && INDIRECT_REF_P (base))
186 ptr = TREE_OPERAND (base, 0);
189 return operand_equal_p (base, decl, 0);
191 && CONSTANT_CLASS_P (base))
197 /* We can end up with dereferencing non-SSA name pointers.
198 Just bail out in this case. */
199 if (TREE_CODE (ptr) != SSA_NAME)
202 /* If we do not have useful points-to information for this pointer
203 we cannot disambiguate anything else. */
204 pi = SSA_NAME_PTR_INFO (ptr);
208 return pt_solution_includes (&pi->pt, decl);
211 /* Return true if dereferenced PTR1 and PTR2 may alias.
212 The caller is responsible for applying TBAA to see if accesses
213 through PTR1 and PTR2 may conflict at all. */
216 ptr_derefs_may_alias_p (tree ptr1, tree ptr2)
218 struct ptr_info_def *pi1, *pi2;
220 /* ADDR_EXPR pointers either just offset another pointer or directly
221 specify the pointed-to set. */
222 if (TREE_CODE (ptr1) == ADDR_EXPR)
224 tree base = get_base_address (TREE_OPERAND (ptr1, 0));
226 && INDIRECT_REF_P (base))
227 ptr1 = TREE_OPERAND (base, 0);
230 return ptr_deref_may_alias_decl_p (ptr2, base);
234 if (TREE_CODE (ptr2) == ADDR_EXPR)
236 tree base = get_base_address (TREE_OPERAND (ptr2, 0));
238 && INDIRECT_REF_P (base))
239 ptr2 = TREE_OPERAND (base, 0);
242 return ptr_deref_may_alias_decl_p (ptr1, base);
247 /* We can end up with dereferencing non-SSA name pointers.
248 Just bail out in this case. */
249 if (TREE_CODE (ptr1) != SSA_NAME
250 || TREE_CODE (ptr2) != SSA_NAME)
253 /* We may end up with two empty points-to solutions for two same pointers.
254 In this case we still want to say both pointers alias, so shortcut
259 /* If we do not have useful points-to information for either pointer
260 we cannot disambiguate anything else. */
261 pi1 = SSA_NAME_PTR_INFO (ptr1);
262 pi2 = SSA_NAME_PTR_INFO (ptr2);
266 /* If both pointers are restrict-qualified try to disambiguate
267 with restrict information. */
268 if (TYPE_RESTRICT (TREE_TYPE (ptr1))
269 && TYPE_RESTRICT (TREE_TYPE (ptr2))
270 && !pt_solutions_same_restrict_base (&pi1->pt, &pi2->pt))
273 /* ??? This does not use TBAA to prune decls from the intersection
274 that not both pointers may access. */
275 return pt_solutions_intersect (&pi1->pt, &pi2->pt);
278 /* Return true if dereferencing PTR may alias *REF.
279 The caller is responsible for applying TBAA to see if PTR
280 may access *REF at all. */
283 ptr_deref_may_alias_ref_p_1 (tree ptr, ao_ref *ref)
285 tree base = ao_ref_base (ref);
287 if (INDIRECT_REF_P (base))
288 return ptr_derefs_may_alias_p (ptr, TREE_OPERAND (base, 0));
289 else if (SSA_VAR_P (base))
290 return ptr_deref_may_alias_decl_p (ptr, base);
296 /* Dump alias information on FILE. */
299 dump_alias_info (FILE *file)
303 = lang_hooks.decl_printable_name (current_function_decl, 2);
304 referenced_var_iterator rvi;
307 fprintf (file, "\n\nAlias information for %s\n\n", funcname);
309 fprintf (file, "Aliased symbols\n\n");
311 FOR_EACH_REFERENCED_VAR (var, rvi)
313 if (may_be_aliased (var))
314 dump_variable (file, var);
317 fprintf (file, "\nCall clobber information\n");
319 fprintf (file, "\nESCAPED");
320 dump_points_to_solution (file, &cfun->gimple_df->escaped);
321 fprintf (file, "\nCALLUSED");
322 dump_points_to_solution (file, &cfun->gimple_df->callused);
324 fprintf (file, "\n\nFlow-insensitive points-to information\n\n");
326 for (i = 1; i < num_ssa_names; i++)
328 tree ptr = ssa_name (i);
329 struct ptr_info_def *pi;
332 || SSA_NAME_IN_FREE_LIST (ptr))
335 pi = SSA_NAME_PTR_INFO (ptr);
337 dump_points_to_info_for (file, ptr);
340 fprintf (file, "\n");
344 /* Dump alias information on stderr. */
347 debug_alias_info (void)
349 dump_alias_info (stderr);
353 /* Return the alias information associated with pointer T. It creates a
354 new instance if none existed. */
356 struct ptr_info_def *
357 get_ptr_info (tree t)
359 struct ptr_info_def *pi;
361 gcc_assert (POINTER_TYPE_P (TREE_TYPE (t)));
363 pi = SSA_NAME_PTR_INFO (t);
366 pi = GGC_CNEW (struct ptr_info_def);
367 pt_solution_reset (&pi->pt);
368 SSA_NAME_PTR_INFO (t) = pi;
374 /* Dump the points-to set *PT into FILE. */
377 dump_points_to_solution (FILE *file, struct pt_solution *pt)
380 fprintf (file, ", points-to anything");
383 fprintf (file, ", points-to non-local");
386 fprintf (file, ", points-to 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)");
400 /* Dump points-to information for SSA_NAME PTR into FILE. */
403 dump_points_to_info_for (FILE *file, tree ptr)
405 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
407 print_generic_expr (file, ptr, dump_flags);
410 dump_points_to_solution (file, &pi->pt);
412 fprintf (file, ", points-to anything");
414 fprintf (file, "\n");
418 /* Dump points-to information for VAR into stderr. */
421 debug_points_to_info_for (tree var)
423 dump_points_to_info_for (stderr, var);
427 /* Initializes the alias-oracle reference representation *R from REF. */
430 ao_ref_init (ao_ref *r, tree ref)
437 r->ref_alias_set = -1;
438 r->base_alias_set = -1;
441 /* Returns the base object of the memory reference *REF. */
444 ao_ref_base (ao_ref *ref)
448 ref->base = get_ref_base_and_extent (ref->ref, &ref->offset, &ref->size,
453 /* Returns the base object alias set of the memory reference *REF. */
455 static alias_set_type ATTRIBUTE_UNUSED
456 ao_ref_base_alias_set (ao_ref *ref)
458 if (ref->base_alias_set != -1)
459 return ref->base_alias_set;
460 ref->base_alias_set = get_alias_set (ao_ref_base (ref));
461 return ref->base_alias_set;
464 /* Returns the reference alias set of the memory reference *REF. */
467 ao_ref_alias_set (ao_ref *ref)
469 if (ref->ref_alias_set != -1)
470 return ref->ref_alias_set;
471 ref->ref_alias_set = get_alias_set (ref->ref);
472 return ref->ref_alias_set;
475 /* Init an alias-oracle reference representation from a gimple pointer
476 PTR and a gimple size SIZE in bytes. If SIZE is NULL_TREE the the
477 size is assumed to be unknown. The access is assumed to be only
478 to or after of the pointer target, not before it. */
481 ao_ref_init_from_ptr_and_size (ao_ref *ref, tree ptr, tree size)
483 HOST_WIDE_INT t1, t2;
484 ref->ref = NULL_TREE;
485 if (TREE_CODE (ptr) == ADDR_EXPR)
486 ref->base = get_ref_base_and_extent (TREE_OPERAND (ptr, 0),
487 &ref->offset, &t1, &t2);
490 ref->base = build1 (INDIRECT_REF, char_type_node, ptr);
494 && host_integerp (size, 0)
495 && TREE_INT_CST_LOW (size) * 8 / 8 == TREE_INT_CST_LOW (size))
496 ref->max_size = ref->size = TREE_INT_CST_LOW (size) * 8;
498 ref->max_size = ref->size = -1;
499 ref->ref_alias_set = 0;
500 ref->base_alias_set = 0;
503 /* Return 1 if TYPE1 and TYPE2 are to be considered equivalent for the
504 purpose of TBAA. Return 0 if they are distinct and -1 if we cannot
508 same_type_for_tbaa (tree type1, tree type2)
510 type1 = TYPE_MAIN_VARIANT (type1);
511 type2 = TYPE_MAIN_VARIANT (type2);
513 /* If we would have to do structural comparison bail out. */
514 if (TYPE_STRUCTURAL_EQUALITY_P (type1)
515 || TYPE_STRUCTURAL_EQUALITY_P (type2))
518 /* Compare the canonical types. */
519 if (TYPE_CANONICAL (type1) == TYPE_CANONICAL (type2))
522 /* ??? Array types are not properly unified in all cases as we have
523 spurious changes in the index types for example. Removing this
524 causes all sorts of problems with the Fortran frontend. */
525 if (TREE_CODE (type1) == ARRAY_TYPE
526 && TREE_CODE (type2) == ARRAY_TYPE)
529 /* The types are known to be not equal. */
533 /* Determine if the two component references REF1 and REF2 which are
534 based on access types TYPE1 and TYPE2 and of which at least one is based
535 on an indirect reference may alias. */
538 nonaliasing_component_refs_p (tree ref1, tree type1,
539 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
540 tree ref2, tree type2,
541 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
543 /* If one reference is a component references through pointers try to find a
544 common base and apply offset based disambiguation. This handles
546 struct A { int i; int j; } *q;
547 struct B { struct A a; int k; } *p;
548 disambiguating q->i and p->a.j. */
552 /* Now search for the type1 in the access path of ref2. This
553 would be a common base for doing offset based disambiguation on. */
555 while (handled_component_p (*refp)
556 && same_type_for_tbaa (TREE_TYPE (*refp), type1) == 0)
557 refp = &TREE_OPERAND (*refp, 0);
558 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type1);
559 /* If we couldn't compare types we have to bail out. */
562 else if (same_p == 1)
564 HOST_WIDE_INT offadj, sztmp, msztmp;
565 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
567 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
569 /* If we didn't find a common base, try the other way around. */
571 while (handled_component_p (*refp)
572 && same_type_for_tbaa (TREE_TYPE (*refp), type2) == 0)
573 refp = &TREE_OPERAND (*refp, 0);
574 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type2);
575 /* If we couldn't compare types we have to bail out. */
578 else if (same_p == 1)
580 HOST_WIDE_INT offadj, sztmp, msztmp;
581 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
583 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
585 /* If we have two type access paths B1.path1 and B2.path2 they may
586 only alias if either B1 is in B2.path2 or B2 is in B1.path1. */
590 /* Return true if two memory references based on the variables BASE1
591 and BASE2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
592 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. */
595 decl_refs_may_alias_p (tree base1,
596 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
598 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
600 gcc_assert (SSA_VAR_P (base1) && SSA_VAR_P (base2));
602 /* If both references are based on different variables, they cannot alias. */
603 if (!operand_equal_p (base1, base2, 0))
606 /* If both references are based on the same variable, they cannot alias if
607 the accesses do not overlap. */
608 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
611 /* Return true if an indirect reference based on *PTR1 constrained
612 to [OFFSET1, OFFSET1 + MAX_SIZE1) may alias a variable based on BASE2
613 constrained to [OFFSET2, OFFSET2 + MAX_SIZE2). *PTR1 and BASE2 have
614 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
615 in which case they are computed on-demand. REF1 and REF2
616 if non-NULL are the complete memory reference trees. */
619 indirect_ref_may_alias_decl_p (tree ref1, tree ptr1,
620 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
621 alias_set_type base1_alias_set,
622 tree ref2, tree base2,
623 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
624 alias_set_type base2_alias_set)
626 /* If only one reference is based on a variable, they cannot alias if
627 the pointer access is beyond the extent of the variable access.
628 (the pointer base cannot validly point to an offset less than zero
630 They also cannot alias if the pointer may not point to the decl. */
632 && !ranges_overlap_p (offset1, max_size1, 0, offset2 + max_size2))
634 if (!ptr_deref_may_alias_decl_p (ptr1, base2))
637 /* Disambiguations that rely on strict aliasing rules follow. */
638 if (!flag_strict_aliasing)
641 /* If the alias set for a pointer access is zero all bets are off. */
642 if (base1_alias_set == -1)
643 base1_alias_set = get_deref_alias_set (ptr1);
644 if (base1_alias_set == 0)
646 if (base2_alias_set == -1)
647 base2_alias_set = get_alias_set (base2);
649 /* If both references are through the same type, they do not alias
650 if the accesses do not overlap. This does extra disambiguation
651 for mixed/pointer accesses but requires strict aliasing. */
652 if (same_type_for_tbaa (TREE_TYPE (TREE_TYPE (ptr1)),
653 TREE_TYPE (base2)) == 1)
654 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
656 /* The only way to access a variable is through a pointer dereference
657 of the same alias set or a subset of it. */
658 if (base1_alias_set != base2_alias_set
659 && !alias_set_subset_of (base1_alias_set, base2_alias_set))
662 /* Do access-path based disambiguation. */
664 && handled_component_p (ref1)
665 && handled_component_p (ref2))
666 return nonaliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)),
668 ref2, TREE_TYPE (base2),
674 /* Return true if two indirect references based on *PTR1
675 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
676 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have
677 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
678 in which case they are computed on-demand. REF1 and REF2
679 if non-NULL are the complete memory reference trees. */
682 indirect_refs_may_alias_p (tree ref1, tree ptr1,
683 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
684 alias_set_type base1_alias_set,
685 tree ref2, tree ptr2,
686 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
687 alias_set_type base2_alias_set)
689 /* If both bases are based on pointers they cannot alias if they may not
690 point to the same memory object or if they point to the same object
691 and the accesses do not overlap. */
692 if (operand_equal_p (ptr1, ptr2, 0))
693 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
694 if (!ptr_derefs_may_alias_p (ptr1, ptr2))
697 /* Disambiguations that rely on strict aliasing rules follow. */
698 if (!flag_strict_aliasing)
701 /* If the alias set for a pointer access is zero all bets are off. */
702 if (base1_alias_set == -1)
703 base1_alias_set = get_deref_alias_set (ptr1);
704 if (base1_alias_set == 0)
706 if (base2_alias_set == -1)
707 base2_alias_set = get_deref_alias_set (ptr2);
708 if (base2_alias_set == 0)
711 /* If both references are through the same type, they do not alias
712 if the accesses do not overlap. This does extra disambiguation
713 for mixed/pointer accesses but requires strict aliasing. */
714 if (same_type_for_tbaa (TREE_TYPE (TREE_TYPE (ptr1)),
715 TREE_TYPE (TREE_TYPE (ptr2))) == 1)
716 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
718 /* Do type-based disambiguation. */
719 if (base1_alias_set != base2_alias_set
720 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
723 /* Do access-path based disambiguation. */
725 && handled_component_p (ref1)
726 && handled_component_p (ref2))
727 return nonaliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)),
729 ref2, TREE_TYPE (TREE_TYPE (ptr2)),
735 /* Return true, if the two memory references REF1 and REF2 may alias. */
738 refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
741 HOST_WIDE_INT offset1 = 0, offset2 = 0;
742 HOST_WIDE_INT size1 = -1, size2 = -1;
743 HOST_WIDE_INT max_size1 = -1, max_size2 = -1;
744 bool var1_p, var2_p, ind1_p, ind2_p;
747 gcc_assert ((!ref1->ref
748 || SSA_VAR_P (ref1->ref)
749 || handled_component_p (ref1->ref)
750 || INDIRECT_REF_P (ref1->ref)
751 || TREE_CODE (ref1->ref) == TARGET_MEM_REF)
753 || SSA_VAR_P (ref2->ref)
754 || handled_component_p (ref2->ref)
755 || INDIRECT_REF_P (ref2->ref)
756 || TREE_CODE (ref2->ref) == TARGET_MEM_REF));
758 /* Decompose the references into their base objects and the access. */
759 base1 = ao_ref_base (ref1);
760 offset1 = ref1->offset;
762 max_size1 = ref1->max_size;
763 base2 = ao_ref_base (ref2);
764 offset2 = ref2->offset;
766 max_size2 = ref2->max_size;
768 /* We can end up with registers or constants as bases for example from
769 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
770 which is seen as a struct copy. */
771 if (TREE_CODE (base1) == SSA_NAME
772 || TREE_CODE (base2) == SSA_NAME
773 || is_gimple_min_invariant (base1)
774 || is_gimple_min_invariant (base2)
775 || TREE_CODE (base1) == CONSTRUCTOR
776 || TREE_CODE (base2) == CONSTRUCTOR)
779 /* Defer to simple offset based disambiguation if we have
780 references based on two decls. Do this before defering to
781 TBAA to handle must-alias cases in conformance with the
782 GCC extension of allowing type-punning through unions. */
783 var1_p = SSA_VAR_P (base1);
784 var2_p = SSA_VAR_P (base2);
785 if (var1_p && var2_p)
786 return decl_refs_may_alias_p (base1, offset1, max_size1,
787 base2, offset2, max_size2);
789 /* First defer to TBAA if possible. */
791 && flag_strict_aliasing
792 && !alias_sets_conflict_p (ao_ref_alias_set (ref1),
793 ao_ref_alias_set (ref2)))
796 /* If one reference is a TARGET_MEM_REF weird things are allowed. Still
797 TBAA disambiguation based on the access type is possible, so bail
798 out only after that check. */
799 if ((ref1->ref && TREE_CODE (ref1->ref) == TARGET_MEM_REF)
800 || (ref2->ref && TREE_CODE (ref2->ref) == TARGET_MEM_REF))
803 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */
804 ind1_p = INDIRECT_REF_P (base1);
805 ind2_p = INDIRECT_REF_P (base2);
806 set = tbaa_p ? -1 : 0;
807 if (var1_p && ind2_p)
808 return indirect_ref_may_alias_decl_p (ref2->ref, TREE_OPERAND (base2, 0),
809 offset2, max_size2, set,
811 offset1, max_size1, set);
812 else if (ind1_p && var2_p)
813 return indirect_ref_may_alias_decl_p (ref1->ref, TREE_OPERAND (base1, 0),
814 offset1, max_size1, set,
816 offset2, max_size2, set);
817 else if (ind1_p && ind2_p)
818 return indirect_refs_may_alias_p (ref1->ref, TREE_OPERAND (base1, 0),
819 offset1, max_size1, set,
820 ref2->ref, TREE_OPERAND (base2, 0),
821 offset2, max_size2, set);
827 refs_may_alias_p (tree ref1, tree ref2)
831 ao_ref_init (&r1, ref1);
832 ao_ref_init (&r2, ref2);
833 res = refs_may_alias_p_1 (&r1, &r2, true);
835 ++alias_stats.refs_may_alias_p_may_alias;
837 ++alias_stats.refs_may_alias_p_no_alias;
841 /* Returns true if there is a anti-dependence for the STORE that
842 executes after the LOAD. */
845 refs_anti_dependent_p (tree load, tree store)
848 ao_ref_init (&r1, load);
849 ao_ref_init (&r2, store);
850 return refs_may_alias_p_1 (&r1, &r2, false);
853 /* Returns true if there is a output dependence for the stores
854 STORE1 and STORE2. */
857 refs_output_dependent_p (tree store1, tree store2)
860 ao_ref_init (&r1, store1);
861 ao_ref_init (&r2, store2);
862 return refs_may_alias_p_1 (&r1, &r2, false);
865 /* If the call CALL may use the memory reference REF return true,
866 otherwise return false. */
869 ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
873 int flags = gimple_call_flags (call);
875 /* Const functions without a static chain do not implicitly use memory. */
876 if (!gimple_call_chain (call)
877 && (flags & (ECF_CONST|ECF_NOVOPS)))
880 base = ao_ref_base (ref);
884 /* If the reference is based on a decl that is not aliased the call
885 cannot possibly use it. */
887 && !may_be_aliased (base)
888 /* But local statics can be used through recursion. */
889 && !is_global_var (base))
892 callee = gimple_call_fndecl (call);
894 /* Handle those builtin functions explicitly that do not act as
895 escape points. See tree-ssa-structalias.c:find_func_aliases
896 for the list of builtins we might need to handle here. */
897 if (callee != NULL_TREE
898 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
899 switch (DECL_FUNCTION_CODE (callee))
901 /* All the following functions clobber memory pointed to by
902 their first argument. */
903 case BUILT_IN_STRCPY:
904 case BUILT_IN_STRNCPY:
906 case BUILT_IN_MEMCPY:
907 case BUILT_IN_MEMMOVE:
908 case BUILT_IN_MEMPCPY:
909 case BUILT_IN_STPCPY:
910 case BUILT_IN_STPNCPY:
911 case BUILT_IN_STRCAT:
912 case BUILT_IN_STRNCAT:
915 tree size = NULL_TREE;
916 if (gimple_call_num_args (call) == 3)
917 size = gimple_call_arg (call, 2);
918 ao_ref_init_from_ptr_and_size (&dref,
919 gimple_call_arg (call, 1),
921 return refs_may_alias_p_1 (&dref, ref, false);
923 /* The following builtins do not read from memory. */
925 case BUILT_IN_MEMSET:
927 case BUILT_IN_FREXPF:
928 case BUILT_IN_FREXPL:
929 case BUILT_IN_GAMMA_R:
930 case BUILT_IN_GAMMAF_R:
931 case BUILT_IN_GAMMAL_R:
932 case BUILT_IN_LGAMMA_R:
933 case BUILT_IN_LGAMMAF_R:
934 case BUILT_IN_LGAMMAL_R:
938 case BUILT_IN_REMQUO:
939 case BUILT_IN_REMQUOF:
940 case BUILT_IN_REMQUOL:
941 case BUILT_IN_SINCOS:
942 case BUILT_IN_SINCOSF:
943 case BUILT_IN_SINCOSL:
947 /* Fallthru to general call handling. */;
950 /* Check if base is a global static variable that is not read
952 if (TREE_CODE (base) == VAR_DECL
953 && TREE_STATIC (base)
954 && !TREE_PUBLIC (base))
958 if (callee != NULL_TREE
960 = ipa_reference_get_not_read_global (cgraph_node (callee)))
961 && bitmap_bit_p (not_read, DECL_UID (base)))
965 /* If the base variable is call-used or call-clobbered then
967 if (flags & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS))
971 if (is_call_used (base))
974 else if (INDIRECT_REF_P (base)
975 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
977 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
981 if (pt_solution_includes_global (&pi->pt)
982 || pt_solutions_intersect (&cfun->gimple_df->callused, &pi->pt)
983 || pt_solutions_intersect (&cfun->gimple_df->escaped, &pi->pt))
993 if (is_call_clobbered (base))
996 else if (INDIRECT_REF_P (base)
997 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
999 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1003 if (pt_solution_includes_global (&pi->pt)
1004 || pt_solutions_intersect (&cfun->gimple_df->escaped, &pi->pt))
1011 /* Inspect call arguments for passed-by-value aliases. */
1013 for (i = 0; i < gimple_call_num_args (call); ++i)
1015 tree op = gimple_call_arg (call, i);
1017 if (TREE_CODE (op) == EXC_PTR_EXPR
1018 || TREE_CODE (op) == FILTER_EXPR)
1021 if (TREE_CODE (op) == WITH_SIZE_EXPR)
1022 op = TREE_OPERAND (op, 0);
1024 if (TREE_CODE (op) != SSA_NAME
1025 && !is_gimple_min_invariant (op))
1028 ao_ref_init (&r, op);
1029 if (refs_may_alias_p_1 (&r, ref, true))
1038 ref_maybe_used_by_call_p (gimple call, tree ref)
1042 ao_ref_init (&r, ref);
1043 res = ref_maybe_used_by_call_p_1 (call, &r);
1045 ++alias_stats.ref_maybe_used_by_call_p_may_alias;
1047 ++alias_stats.ref_maybe_used_by_call_p_no_alias;
1052 /* If the statement STMT may use the memory reference REF return
1053 true, otherwise return false. */
1056 ref_maybe_used_by_stmt_p (gimple stmt, tree ref)
1058 if (is_gimple_assign (stmt))
1062 /* All memory assign statements are single. */
1063 if (!gimple_assign_single_p (stmt))
1066 rhs = gimple_assign_rhs1 (stmt);
1067 if (is_gimple_reg (rhs)
1068 || is_gimple_min_invariant (rhs)
1069 || gimple_assign_rhs_code (stmt) == CONSTRUCTOR)
1072 return refs_may_alias_p (rhs, ref);
1074 else if (is_gimple_call (stmt))
1075 return ref_maybe_used_by_call_p (stmt, ref);
1080 /* If the call in statement CALL may clobber the memory reference REF
1081 return true, otherwise return false. */
1084 call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
1089 /* If the call is pure or const it cannot clobber anything. */
1090 if (gimple_call_flags (call)
1091 & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS))
1094 base = ao_ref_base (ref);
1098 if (TREE_CODE (base) == SSA_NAME
1099 || CONSTANT_CLASS_P (base))
1102 /* If the reference is based on a decl that is not aliased the call
1103 cannot possibly clobber it. */
1105 && !may_be_aliased (base)
1106 /* But local non-readonly statics can be modified through recursion
1107 or the call may implement a threading barrier which we must
1108 treat as may-def. */
1109 && (TREE_READONLY (base)
1110 || !is_global_var (base)))
1113 callee = gimple_call_fndecl (call);
1115 /* Handle those builtin functions explicitly that do not act as
1116 escape points. See tree-ssa-structalias.c:find_func_aliases
1117 for the list of builtins we might need to handle here. */
1118 if (callee != NULL_TREE
1119 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1120 switch (DECL_FUNCTION_CODE (callee))
1122 /* All the following functions clobber memory pointed to by
1123 their first argument. */
1124 case BUILT_IN_STRCPY:
1125 case BUILT_IN_STRNCPY:
1126 case BUILT_IN_BCOPY:
1127 case BUILT_IN_MEMCPY:
1128 case BUILT_IN_MEMMOVE:
1129 case BUILT_IN_MEMPCPY:
1130 case BUILT_IN_STPCPY:
1131 case BUILT_IN_STPNCPY:
1132 case BUILT_IN_STRCAT:
1133 case BUILT_IN_STRNCAT:
1134 case BUILT_IN_MEMSET:
1137 tree size = NULL_TREE;
1138 if (gimple_call_num_args (call) == 3)
1139 size = gimple_call_arg (call, 2);
1140 ao_ref_init_from_ptr_and_size (&dref,
1141 gimple_call_arg (call, 0),
1143 return refs_may_alias_p_1 (&dref, ref, false);
1145 /* Freeing memory kills the pointed-to memory. More importantly
1146 the call has to serve as a barrier for moving loads and stores
1150 tree ptr = gimple_call_arg (call, 0);
1151 return ptr_deref_may_alias_ref_p_1 (ptr, ref);
1153 case BUILT_IN_GAMMA_R:
1154 case BUILT_IN_GAMMAF_R:
1155 case BUILT_IN_GAMMAL_R:
1156 case BUILT_IN_LGAMMA_R:
1157 case BUILT_IN_LGAMMAF_R:
1158 case BUILT_IN_LGAMMAL_R:
1160 tree out = gimple_call_arg (call, 1);
1161 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1163 if (flag_errno_math)
1167 case BUILT_IN_FREXP:
1168 case BUILT_IN_FREXPF:
1169 case BUILT_IN_FREXPL:
1171 case BUILT_IN_MODFF:
1172 case BUILT_IN_MODFL:
1174 tree out = gimple_call_arg (call, 1);
1175 return ptr_deref_may_alias_ref_p_1 (out, ref);
1177 case BUILT_IN_REMQUO:
1178 case BUILT_IN_REMQUOF:
1179 case BUILT_IN_REMQUOL:
1181 tree out = gimple_call_arg (call, 2);
1182 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1184 if (flag_errno_math)
1188 case BUILT_IN_SINCOS:
1189 case BUILT_IN_SINCOSF:
1190 case BUILT_IN_SINCOSL:
1192 tree sin = gimple_call_arg (call, 1);
1193 tree cos = gimple_call_arg (call, 2);
1194 return (ptr_deref_may_alias_ref_p_1 (sin, ref)
1195 || ptr_deref_may_alias_ref_p_1 (cos, ref));
1198 /* Fallthru to general call handling. */;
1201 /* Check if base is a global static variable that is not written
1203 if (callee != NULL_TREE
1204 && TREE_CODE (base) == VAR_DECL
1205 && TREE_STATIC (base)
1206 && !TREE_PUBLIC (base))
1211 = ipa_reference_get_not_written_global (cgraph_node (callee)))
1212 && bitmap_bit_p (not_written, DECL_UID (base)))
1217 return is_call_clobbered (base);
1218 else if (INDIRECT_REF_P (base)
1219 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1221 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1225 return (pt_solution_includes_global (&pi->pt)
1226 || pt_solutions_intersect (&cfun->gimple_df->escaped, &pi->pt));
1232 static bool ATTRIBUTE_UNUSED
1233 call_may_clobber_ref_p (gimple call, tree ref)
1237 ao_ref_init (&r, ref);
1238 res = call_may_clobber_ref_p_1 (call, &r);
1240 ++alias_stats.call_may_clobber_ref_p_may_alias;
1242 ++alias_stats.call_may_clobber_ref_p_no_alias;
1247 /* If the statement STMT may clobber the memory reference REF return true,
1248 otherwise return false. */
1251 stmt_may_clobber_ref_p_1 (gimple stmt, ao_ref *ref)
1253 if (is_gimple_call (stmt))
1255 tree lhs = gimple_call_lhs (stmt);
1257 && !is_gimple_reg (lhs))
1260 ao_ref_init (&r, lhs);
1261 if (refs_may_alias_p_1 (ref, &r, true))
1265 return call_may_clobber_ref_p_1 (stmt, ref);
1267 else if (is_gimple_assign (stmt))
1270 ao_ref_init (&r, gimple_assign_lhs (stmt));
1271 return refs_may_alias_p_1 (ref, &r, true);
1273 else if (gimple_code (stmt) == GIMPLE_ASM)
1280 stmt_may_clobber_ref_p (gimple stmt, tree ref)
1283 ao_ref_init (&r, ref);
1284 return stmt_may_clobber_ref_p_1 (stmt, &r);
1288 static tree get_continuation_for_phi (gimple, ao_ref *, bitmap *);
1290 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand
1291 TARGET or a statement clobbering the memory reference REF in which
1292 case false is returned. The walk starts with VUSE, one argument of PHI. */
1295 maybe_skip_until (gimple phi, tree target, ao_ref *ref,
1296 tree vuse, bitmap *visited)
1299 *visited = BITMAP_ALLOC (NULL);
1301 bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi)));
1303 /* Walk until we hit the target. */
1304 while (vuse != target)
1306 gimple def_stmt = SSA_NAME_DEF_STMT (vuse);
1307 /* Recurse for PHI nodes. */
1308 if (gimple_code (def_stmt) == GIMPLE_PHI)
1310 /* An already visited PHI node ends the walk successfully. */
1311 if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt))))
1313 vuse = get_continuation_for_phi (def_stmt, ref, visited);
1318 /* A clobbering statement or the end of the IL ends it failing. */
1319 else if (gimple_nop_p (def_stmt)
1320 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1322 vuse = gimple_vuse (def_stmt);
1327 /* Starting from a PHI node for the virtual operand of the memory reference
1328 REF find a continuation virtual operand that allows to continue walking
1329 statements dominating PHI skipping only statements that cannot possibly
1330 clobber REF. Returns NULL_TREE if no suitable virtual operand can
1334 get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited)
1336 unsigned nargs = gimple_phi_num_args (phi);
1338 /* Through a single-argument PHI we can simply look through. */
1340 return PHI_ARG_DEF (phi, 0);
1342 /* For two arguments try to skip non-aliasing code until we hit
1343 the phi argument definition that dominates the other one. */
1346 tree arg0 = PHI_ARG_DEF (phi, 0);
1347 tree arg1 = PHI_ARG_DEF (phi, 1);
1348 gimple def0 = SSA_NAME_DEF_STMT (arg0);
1349 gimple def1 = SSA_NAME_DEF_STMT (arg1);
1353 else if (gimple_nop_p (def0)
1354 || (!gimple_nop_p (def1)
1355 && dominated_by_p (CDI_DOMINATORS,
1356 gimple_bb (def1), gimple_bb (def0))))
1358 if (maybe_skip_until (phi, arg0, ref, arg1, visited))
1361 else if (gimple_nop_p (def1)
1362 || dominated_by_p (CDI_DOMINATORS,
1363 gimple_bb (def0), gimple_bb (def1)))
1365 if (maybe_skip_until (phi, arg1, ref, arg0, visited))
1373 /* Based on the memory reference REF and its virtual use VUSE call
1374 WALKER for each virtual use that is equivalent to VUSE, including VUSE
1375 itself. That is, for each virtual use for which its defining statement
1376 does not clobber REF.
1378 WALKER is called with REF, the current virtual use and DATA. If
1379 WALKER returns non-NULL the walk stops and its result is returned.
1380 At the end of a non-successful walk NULL is returned.
1382 TRANSLATE if non-NULL is called with a pointer to REF, the virtual
1383 use which definition is a statement that may clobber REF and DATA.
1384 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
1385 If TRANSLATE returns non-NULL the walk stops and its result is returned.
1386 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
1387 to adjust REF and *DATA to make that valid.
1389 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
1392 walk_non_aliased_vuses (ao_ref *ref, tree vuse,
1393 void *(*walker)(ao_ref *, tree, void *),
1394 void *(*translate)(ao_ref *, tree, void *), void *data)
1396 bitmap visited = NULL;
1399 timevar_push (TV_ALIAS_STMT_WALK);
1405 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1406 res = (*walker) (ref, vuse, data);
1410 def_stmt = SSA_NAME_DEF_STMT (vuse);
1411 if (gimple_nop_p (def_stmt))
1413 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1414 vuse = get_continuation_for_phi (def_stmt, ref, &visited);
1417 if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
1421 res = (*translate) (ref, vuse, data);
1422 /* Failed lookup and translation. */
1423 if (res == (void *)-1)
1428 /* Lookup succeeded. */
1429 else if (res != NULL)
1431 /* Translation succeeded, continue walking. */
1433 vuse = gimple_vuse (def_stmt);
1439 BITMAP_FREE (visited);
1441 timevar_pop (TV_ALIAS_STMT_WALK);
1447 /* Based on the memory reference REF call WALKER for each vdef which
1448 defining statement may clobber REF, starting with VDEF. If REF
1449 is NULL_TREE, each defining statement is visited.
1451 WALKER is called with REF, the current vdef and DATA. If WALKER
1452 returns true the walk is stopped, otherwise it continues.
1454 At PHI nodes walk_aliased_vdefs forks into one walk for reach
1455 PHI argument (but only one walk continues on merge points), the
1456 return value is true if any of the walks was successful.
1458 The function returns the number of statements walked. */
1461 walk_aliased_vdefs_1 (ao_ref *ref, tree vdef,
1462 bool (*walker)(ao_ref *, tree, void *), void *data,
1463 bitmap *visited, unsigned int cnt)
1467 gimple def_stmt = SSA_NAME_DEF_STMT (vdef);
1470 && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef)))
1473 if (gimple_nop_p (def_stmt))
1475 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1479 *visited = BITMAP_ALLOC (NULL);
1480 for (i = 0; i < gimple_phi_num_args (def_stmt); ++i)
1481 cnt += walk_aliased_vdefs_1 (ref, gimple_phi_arg_def (def_stmt, i),
1482 walker, data, visited, 0);
1486 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1489 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1490 && (*walker) (ref, vdef, data))
1493 vdef = gimple_vuse (def_stmt);
1499 walk_aliased_vdefs (ao_ref *ref, tree vdef,
1500 bool (*walker)(ao_ref *, tree, void *), void *data,
1503 bitmap local_visited = NULL;
1506 timevar_push (TV_ALIAS_STMT_WALK);
1508 ret = walk_aliased_vdefs_1 (ref, vdef, walker, data,
1509 visited ? visited : &local_visited, 0);
1511 BITMAP_FREE (local_visited);
1513 timevar_pop (TV_ALIAS_STMT_WALK);