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 /* 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_alloc_cleared_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 unit escaped");
410 fprintf (file, ", points-to NULL");
414 fprintf (file, ", points-to vars: ");
415 dump_decl_set (file, pt->vars);
416 if (pt->vars_contains_global)
417 fprintf (file, " (includes global vars)");
418 if (pt->vars_contains_restrict)
419 fprintf (file, " (includes restrict tags)");
423 /* Dump points-to information for SSA_NAME PTR into FILE. */
426 dump_points_to_info_for (FILE *file, tree ptr)
428 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
430 print_generic_expr (file, ptr, dump_flags);
433 dump_points_to_solution (file, &pi->pt);
435 fprintf (file, ", points-to anything");
437 fprintf (file, "\n");
441 /* Dump points-to information for VAR into stderr. */
444 debug_points_to_info_for (tree var)
446 dump_points_to_info_for (stderr, var);
450 /* Initializes the alias-oracle reference representation *R from REF. */
453 ao_ref_init (ao_ref *r, tree ref)
460 r->ref_alias_set = -1;
461 r->base_alias_set = -1;
464 /* Returns the base object of the memory reference *REF. */
467 ao_ref_base (ao_ref *ref)
471 ref->base = get_ref_base_and_extent (ref->ref, &ref->offset, &ref->size,
476 /* Returns the base object alias set of the memory reference *REF. */
478 static alias_set_type
479 ao_ref_base_alias_set (ao_ref *ref)
482 if (ref->base_alias_set != -1)
483 return ref->base_alias_set;
487 while (handled_component_p (base_ref))
488 base_ref = TREE_OPERAND (base_ref, 0);
489 ref->base_alias_set = get_alias_set (base_ref);
490 return ref->base_alias_set;
493 /* Returns the reference alias set of the memory reference *REF. */
496 ao_ref_alias_set (ao_ref *ref)
498 if (ref->ref_alias_set != -1)
499 return ref->ref_alias_set;
500 ref->ref_alias_set = get_alias_set (ref->ref);
501 return ref->ref_alias_set;
504 /* Init an alias-oracle reference representation from a gimple pointer
505 PTR and a gimple size SIZE in bytes. If SIZE is NULL_TREE the the
506 size is assumed to be unknown. The access is assumed to be only
507 to or after of the pointer target, not before it. */
510 ao_ref_init_from_ptr_and_size (ao_ref *ref, tree ptr, tree size)
512 HOST_WIDE_INT t1, t2;
513 ref->ref = NULL_TREE;
514 if (TREE_CODE (ptr) == ADDR_EXPR)
515 ref->base = get_ref_base_and_extent (TREE_OPERAND (ptr, 0),
516 &ref->offset, &t1, &t2);
519 ref->base = build2 (MEM_REF, char_type_node,
520 ptr, null_pointer_node);
524 && host_integerp (size, 0)
525 && TREE_INT_CST_LOW (size) * 8 / 8 == TREE_INT_CST_LOW (size))
526 ref->max_size = ref->size = TREE_INT_CST_LOW (size) * 8;
528 ref->max_size = ref->size = -1;
529 ref->ref_alias_set = 0;
530 ref->base_alias_set = 0;
533 /* Return 1 if TYPE1 and TYPE2 are to be considered equivalent for the
534 purpose of TBAA. Return 0 if they are distinct and -1 if we cannot
538 same_type_for_tbaa (tree type1, tree type2)
540 type1 = TYPE_MAIN_VARIANT (type1);
541 type2 = TYPE_MAIN_VARIANT (type2);
543 /* If we would have to do structural comparison bail out. */
544 if (TYPE_STRUCTURAL_EQUALITY_P (type1)
545 || TYPE_STRUCTURAL_EQUALITY_P (type2))
548 /* Compare the canonical types. */
549 if (TYPE_CANONICAL (type1) == TYPE_CANONICAL (type2))
552 /* ??? Array types are not properly unified in all cases as we have
553 spurious changes in the index types for example. Removing this
554 causes all sorts of problems with the Fortran frontend. */
555 if (TREE_CODE (type1) == ARRAY_TYPE
556 && TREE_CODE (type2) == ARRAY_TYPE)
559 /* ??? In Ada, an lvalue of an unconstrained type can be used to access an
560 object of one of its constrained subtypes, e.g. when a function with an
561 unconstrained parameter passed by reference is called on an object and
562 inlined. But, even in the case of a fixed size, type and subtypes are
563 not equivalent enough as to share the same TYPE_CANONICAL, since this
564 would mean that conversions between them are useless, whereas they are
565 not (e.g. type and subtypes can have different modes). So, in the end,
566 they are only guaranteed to have the same alias set. */
567 if (get_alias_set (type1) == get_alias_set (type2))
570 /* The types are known to be not equal. */
574 /* Determine if the two component references REF1 and REF2 which are
575 based on access types TYPE1 and TYPE2 and of which at least one is based
576 on an indirect reference may alias. REF2 is the only one that can
577 be a decl in which case REF2_IS_DECL is true.
578 REF1_ALIAS_SET, BASE1_ALIAS_SET, REF2_ALIAS_SET and BASE2_ALIAS_SET
579 are the respective alias sets. */
582 aliasing_component_refs_p (tree ref1, tree type1,
583 alias_set_type ref1_alias_set,
584 alias_set_type base1_alias_set,
585 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
586 tree ref2, tree type2,
587 alias_set_type ref2_alias_set,
588 alias_set_type base2_alias_set,
589 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
592 /* If one reference is a component references through pointers try to find a
593 common base and apply offset based disambiguation. This handles
595 struct A { int i; int j; } *q;
596 struct B { struct A a; int k; } *p;
597 disambiguating q->i and p->a.j. */
601 /* Now search for the type1 in the access path of ref2. This
602 would be a common base for doing offset based disambiguation on. */
604 while (handled_component_p (*refp)
605 && same_type_for_tbaa (TREE_TYPE (*refp), type1) == 0)
606 refp = &TREE_OPERAND (*refp, 0);
607 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type1);
608 /* If we couldn't compare types we have to bail out. */
611 else if (same_p == 1)
613 HOST_WIDE_INT offadj, sztmp, msztmp;
614 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
616 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
618 /* If we didn't find a common base, try the other way around. */
620 while (handled_component_p (*refp)
621 && same_type_for_tbaa (TREE_TYPE (*refp), type2) == 0)
622 refp = &TREE_OPERAND (*refp, 0);
623 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type2);
624 /* If we couldn't compare types we have to bail out. */
627 else if (same_p == 1)
629 HOST_WIDE_INT offadj, sztmp, msztmp;
630 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
632 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
635 /* If we have two type access paths B1.path1 and B2.path2 they may
636 only alias if either B1 is in B2.path2 or B2 is in B1.path1.
637 But we can still have a path that goes B1.path1...B2.path2 with
638 a part that we do not see. So we can only disambiguate now
639 if there is no B2 in the tail of path1 and no B1 on the
641 if (base1_alias_set == ref2_alias_set
642 || alias_set_subset_of (base1_alias_set, ref2_alias_set))
644 /* If this is ptr vs. decl then we know there is no ptr ... decl path. */
646 return (base2_alias_set == ref1_alias_set
647 || alias_set_subset_of (base2_alias_set, ref1_alias_set));
651 /* Return true if two memory references based on the variables BASE1
652 and BASE2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
653 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. */
656 decl_refs_may_alias_p (tree base1,
657 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
659 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
661 gcc_assert (SSA_VAR_P (base1) && SSA_VAR_P (base2));
663 /* If both references are based on different variables, they cannot alias. */
667 /* If both references are based on the same variable, they cannot alias if
668 the accesses do not overlap. */
669 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
672 /* Return true if an indirect reference based on *PTR1 constrained
673 to [OFFSET1, OFFSET1 + MAX_SIZE1) may alias a variable based on BASE2
674 constrained to [OFFSET2, OFFSET2 + MAX_SIZE2). *PTR1 and BASE2 have
675 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
676 in which case they are computed on-demand. REF1 and REF2
677 if non-NULL are the complete memory reference trees. */
680 indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
681 HOST_WIDE_INT offset1,
682 HOST_WIDE_INT max_size1 ATTRIBUTE_UNUSED,
683 alias_set_type ref1_alias_set,
684 alias_set_type base1_alias_set,
685 tree ref2 ATTRIBUTE_UNUSED, tree base2,
686 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
687 alias_set_type ref2_alias_set,
688 alias_set_type base2_alias_set, bool tbaa_p)
690 tree ptr1 = TREE_OPERAND (base1, 0);
692 HOST_WIDE_INT offset1p = offset1, offset2p = offset2;
694 /* The offset embedded in MEM_REFs can be negative. Bias them
695 so that the resulting offset adjustment is positive. */
696 if (TREE_CODE (base1) == MEM_REF)
698 double_int moff = mem_ref_offset (base1);
699 moff = double_int_lshift (moff,
701 ? 3 : exact_log2 (BITS_PER_UNIT),
702 HOST_BITS_PER_DOUBLE_INT, true);
703 if (double_int_negative_p (moff))
704 offset2p += double_int_neg (moff).low;
706 offset1p += moff.low;
709 /* If only one reference is based on a variable, they cannot alias if
710 the pointer access is beyond the extent of the variable access.
711 (the pointer base cannot validly point to an offset less than zero
713 They also cannot alias if the pointer may not point to the decl. */
714 if (!ranges_overlap_p (MAX (0, offset1p), -1, offset2p, max_size2))
716 if (!ptr_deref_may_alias_decl_p (ptr1, base2))
719 /* Disambiguations that rely on strict aliasing rules follow. */
720 if (!flag_strict_aliasing || !tbaa_p)
723 if (TREE_CODE (base1) == MEM_REF)
724 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
726 ptrtype1 = TREE_TYPE (ptr1);
728 /* If the alias set for a pointer access is zero all bets are off. */
729 if (base1_alias_set == -1)
730 base1_alias_set = get_deref_alias_set (ptrtype1);
731 if (base1_alias_set == 0)
733 if (base2_alias_set == -1)
734 base2_alias_set = get_alias_set (base2);
736 /* If both references are through the same type, they do not alias
737 if the accesses do not overlap. This does extra disambiguation
738 for mixed/pointer accesses but requires strict aliasing.
739 For MEM_REFs we require that the component-ref offset we computed
740 is relative to the start of the type which we ensure by
741 comparing rvalue and access type and disregarding the constant
743 if ((TREE_CODE (base1) != MEM_REF
744 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
745 && same_type_for_tbaa (TREE_TYPE (ptrtype1), TREE_TYPE (base2)) == 1)
746 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
748 /* When we are trying to disambiguate an access with a pointer dereference
749 as base versus one with a decl as base we can use both the size
750 of the decl and its dynamic type for extra disambiguation.
751 ??? We do not know anything about the dynamic type of the decl
752 other than that its alias-set contains base2_alias_set as a subset
753 which does not help us here. */
754 /* As we know nothing useful about the dynamic type of the decl just
755 use the usual conflict check rather than a subset test.
756 ??? We could introduce -fvery-strict-aliasing when the language
757 does not allow decls to have a dynamic type that differs from their
758 static type. Then we can check
759 !alias_set_subset_of (base1_alias_set, base2_alias_set) instead. */
760 if (base1_alias_set != base2_alias_set
761 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
763 /* If the size of the access relevant for TBAA through the pointer
764 is bigger than the size of the decl we can't possibly access the
765 decl via that pointer. */
766 if (DECL_SIZE (base2) && COMPLETE_TYPE_P (TREE_TYPE (ptrtype1))
767 && TREE_CODE (DECL_SIZE (base2)) == INTEGER_CST
768 && TREE_CODE (TYPE_SIZE (TREE_TYPE (ptrtype1))) == INTEGER_CST
769 /* ??? This in turn may run afoul when a decl of type T which is
770 a member of union type U is accessed through a pointer to
771 type U and sizeof T is smaller than sizeof U. */
772 && TREE_CODE (TREE_TYPE (ptrtype1)) != UNION_TYPE
773 && TREE_CODE (TREE_TYPE (ptrtype1)) != QUAL_UNION_TYPE
774 && tree_int_cst_lt (DECL_SIZE (base2), TYPE_SIZE (TREE_TYPE (ptrtype1))))
777 /* Do access-path based disambiguation. */
779 && handled_component_p (ref1)
780 && handled_component_p (ref2)
781 && (TREE_CODE (base1) != MEM_REF
782 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1))
783 return aliasing_component_refs_p (ref1, TREE_TYPE (ptrtype1),
784 ref1_alias_set, base1_alias_set,
786 ref2, TREE_TYPE (base2),
787 ref2_alias_set, base2_alias_set,
788 offset2, max_size2, true);
793 /* Return true if two indirect references based on *PTR1
794 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
795 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have
796 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
797 in which case they are computed on-demand. REF1 and REF2
798 if non-NULL are the complete memory reference trees. */
801 indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
802 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
803 alias_set_type ref1_alias_set,
804 alias_set_type base1_alias_set,
805 tree ref2 ATTRIBUTE_UNUSED, tree base2,
806 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
807 alias_set_type ref2_alias_set,
808 alias_set_type base2_alias_set, bool tbaa_p)
810 tree ptr1 = TREE_OPERAND (base1, 0);
811 tree ptr2 = TREE_OPERAND (base2, 0);
812 tree ptrtype1, ptrtype2;
814 /* If both bases are based on pointers they cannot alias if they may not
815 point to the same memory object or if they point to the same object
816 and the accesses do not overlap. */
817 if ((!cfun || gimple_in_ssa_p (cfun))
818 && operand_equal_p (ptr1, ptr2, 0))
820 /* The offset embedded in MEM_REFs can be negative. Bias them
821 so that the resulting offset adjustment is positive. */
822 if (TREE_CODE (base1) == MEM_REF)
824 double_int moff = mem_ref_offset (base1);
825 moff = double_int_lshift (moff,
827 ? 3 : exact_log2 (BITS_PER_UNIT),
828 HOST_BITS_PER_DOUBLE_INT, true);
829 if (double_int_negative_p (moff))
830 offset2 += double_int_neg (moff).low;
834 if (TREE_CODE (base2) == MEM_REF)
836 double_int moff = mem_ref_offset (base2);
837 moff = double_int_lshift (moff,
839 ? 3 : exact_log2 (BITS_PER_UNIT),
840 HOST_BITS_PER_DOUBLE_INT, true);
841 if (double_int_negative_p (moff))
842 offset1 += double_int_neg (moff).low;
846 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
848 if (!ptr_derefs_may_alias_p (ptr1, ptr2))
851 /* Disambiguations that rely on strict aliasing rules follow. */
852 if (!flag_strict_aliasing || !tbaa_p)
855 if (TREE_CODE (base1) == MEM_REF)
856 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
858 ptrtype1 = TREE_TYPE (ptr1);
859 if (TREE_CODE (base2) == MEM_REF)
860 ptrtype2 = TREE_TYPE (TREE_OPERAND (base2, 1));
862 ptrtype2 = TREE_TYPE (ptr2);
864 /* If the alias set for a pointer access is zero all bets are off. */
865 if (base1_alias_set == -1)
866 base1_alias_set = get_deref_alias_set (ptrtype1);
867 if (base1_alias_set == 0)
869 if (base2_alias_set == -1)
870 base2_alias_set = get_deref_alias_set (ptrtype2);
871 if (base2_alias_set == 0)
874 /* If both references are through the same type, they do not alias
875 if the accesses do not overlap. This does extra disambiguation
876 for mixed/pointer accesses but requires strict aliasing. */
877 if ((TREE_CODE (base1) != MEM_REF
878 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
879 && (TREE_CODE (base2) != MEM_REF
880 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1)
881 && same_type_for_tbaa (TREE_TYPE (ptrtype1),
882 TREE_TYPE (ptrtype2)) == 1)
883 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
885 /* Do type-based disambiguation. */
886 if (base1_alias_set != base2_alias_set
887 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
890 /* Do access-path based disambiguation. */
892 && handled_component_p (ref1)
893 && handled_component_p (ref2)
894 && (TREE_CODE (base1) != MEM_REF
895 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
896 && (TREE_CODE (base2) != MEM_REF
897 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1))
898 return aliasing_component_refs_p (ref1, TREE_TYPE (ptrtype1),
899 ref1_alias_set, base1_alias_set,
901 ref2, TREE_TYPE (ptrtype2),
902 ref2_alias_set, base2_alias_set,
903 offset2, max_size2, false);
908 /* Return true, if the two memory references REF1 and REF2 may alias. */
911 refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
914 HOST_WIDE_INT offset1 = 0, offset2 = 0;
915 HOST_WIDE_INT max_size1 = -1, max_size2 = -1;
916 bool var1_p, var2_p, ind1_p, ind2_p;
918 gcc_checking_assert ((!ref1->ref
919 || TREE_CODE (ref1->ref) == SSA_NAME
920 || DECL_P (ref1->ref)
921 || handled_component_p (ref1->ref)
922 || INDIRECT_REF_P (ref1->ref)
923 || TREE_CODE (ref1->ref) == MEM_REF
924 || TREE_CODE (ref1->ref) == TARGET_MEM_REF)
926 || TREE_CODE (ref2->ref) == SSA_NAME
927 || DECL_P (ref2->ref)
928 || handled_component_p (ref2->ref)
929 || INDIRECT_REF_P (ref2->ref)
930 || TREE_CODE (ref2->ref) == MEM_REF
931 || TREE_CODE (ref2->ref) == TARGET_MEM_REF));
933 /* Decompose the references into their base objects and the access. */
934 base1 = ao_ref_base (ref1);
935 offset1 = ref1->offset;
936 max_size1 = ref1->max_size;
937 base2 = ao_ref_base (ref2);
938 offset2 = ref2->offset;
939 max_size2 = ref2->max_size;
941 /* We can end up with registers or constants as bases for example from
942 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
943 which is seen as a struct copy. */
944 if (TREE_CODE (base1) == SSA_NAME
945 || TREE_CODE (base2) == SSA_NAME
946 || TREE_CODE (base1) == CONST_DECL
947 || TREE_CODE (base2) == CONST_DECL
948 || is_gimple_min_invariant (base1)
949 || is_gimple_min_invariant (base2))
952 /* We can end up refering to code via function and label decls.
953 As we likely do not properly track code aliases conservatively
955 if (TREE_CODE (base1) == FUNCTION_DECL
956 || TREE_CODE (base2) == FUNCTION_DECL
957 || TREE_CODE (base1) == LABEL_DECL
958 || TREE_CODE (base2) == LABEL_DECL)
961 /* Defer to simple offset based disambiguation if we have
962 references based on two decls. Do this before defering to
963 TBAA to handle must-alias cases in conformance with the
964 GCC extension of allowing type-punning through unions. */
965 var1_p = SSA_VAR_P (base1);
966 var2_p = SSA_VAR_P (base2);
967 if (var1_p && var2_p)
968 return decl_refs_may_alias_p (base1, offset1, max_size1,
969 base2, offset2, max_size2);
971 ind1_p = INDIRECT_REF_P (base1) || (TREE_CODE (base1) == MEM_REF);
972 ind2_p = INDIRECT_REF_P (base2) || (TREE_CODE (base2) == MEM_REF);
974 /* Canonicalize the pointer-vs-decl case. */
975 if (ind1_p && var2_p)
980 tmp1 = offset1; offset1 = offset2; offset2 = tmp1;
981 tmp1 = max_size1; max_size1 = max_size2; max_size2 = tmp1;
982 tmp2 = base1; base1 = base2; base2 = tmp2;
983 tmp3 = ref1; ref1 = ref2; ref2 = tmp3;
990 /* First defer to TBAA if possible. */
992 && flag_strict_aliasing
993 && !alias_sets_conflict_p (ao_ref_alias_set (ref1),
994 ao_ref_alias_set (ref2)))
997 /* If one reference is a TARGET_MEM_REF weird things are allowed. Still
998 TBAA disambiguation based on the access type is possible, so bail
999 out only after that check. */
1000 if ((ref1->ref && TREE_CODE (ref1->ref) == TARGET_MEM_REF)
1001 || (ref2->ref && TREE_CODE (ref2->ref) == TARGET_MEM_REF))
1004 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */
1005 if (var1_p && ind2_p)
1006 return indirect_ref_may_alias_decl_p (ref2->ref, base2,
1008 ao_ref_alias_set (ref2), -1,
1011 ao_ref_alias_set (ref1),
1012 ao_ref_base_alias_set (ref1),
1014 else if (ind1_p && ind2_p)
1015 return indirect_refs_may_alias_p (ref1->ref, base1,
1017 ao_ref_alias_set (ref1), -1,
1020 ao_ref_alias_set (ref2), -1,
1027 refs_may_alias_p (tree ref1, tree ref2)
1031 ao_ref_init (&r1, ref1);
1032 ao_ref_init (&r2, ref2);
1033 res = refs_may_alias_p_1 (&r1, &r2, true);
1035 ++alias_stats.refs_may_alias_p_may_alias;
1037 ++alias_stats.refs_may_alias_p_no_alias;
1041 /* Returns true if there is a anti-dependence for the STORE that
1042 executes after the LOAD. */
1045 refs_anti_dependent_p (tree load, tree store)
1048 ao_ref_init (&r1, load);
1049 ao_ref_init (&r2, store);
1050 return refs_may_alias_p_1 (&r1, &r2, false);
1053 /* Returns true if there is a output dependence for the stores
1054 STORE1 and STORE2. */
1057 refs_output_dependent_p (tree store1, tree store2)
1060 ao_ref_init (&r1, store1);
1061 ao_ref_init (&r2, store2);
1062 return refs_may_alias_p_1 (&r1, &r2, false);
1065 /* If the call CALL may use the memory reference REF return true,
1066 otherwise return false. */
1069 ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
1073 int flags = gimple_call_flags (call);
1075 /* Const functions without a static chain do not implicitly use memory. */
1076 if (!gimple_call_chain (call)
1077 && (flags & (ECF_CONST|ECF_NOVOPS)))
1080 base = ao_ref_base (ref);
1084 /* If the reference is based on a decl that is not aliased the call
1085 cannot possibly use it. */
1087 && !may_be_aliased (base)
1088 /* But local statics can be used through recursion. */
1089 && !is_global_var (base))
1092 callee = gimple_call_fndecl (call);
1094 /* Handle those builtin functions explicitly that do not act as
1095 escape points. See tree-ssa-structalias.c:find_func_aliases
1096 for the list of builtins we might need to handle here. */
1097 if (callee != NULL_TREE
1098 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1099 switch (DECL_FUNCTION_CODE (callee))
1101 /* All the following functions clobber memory pointed to by
1102 their first argument. */
1103 case BUILT_IN_STRCPY:
1104 case BUILT_IN_STRNCPY:
1105 case BUILT_IN_MEMCPY:
1106 case BUILT_IN_MEMMOVE:
1107 case BUILT_IN_MEMPCPY:
1108 case BUILT_IN_STPCPY:
1109 case BUILT_IN_STPNCPY:
1110 case BUILT_IN_STRCAT:
1111 case BUILT_IN_STRNCAT:
1114 tree size = NULL_TREE;
1115 if (gimple_call_num_args (call) == 3)
1116 size = gimple_call_arg (call, 2);
1117 ao_ref_init_from_ptr_and_size (&dref,
1118 gimple_call_arg (call, 1),
1120 return refs_may_alias_p_1 (&dref, ref, false);
1122 case BUILT_IN_BCOPY:
1125 tree size = gimple_call_arg (call, 2);
1126 ao_ref_init_from_ptr_and_size (&dref,
1127 gimple_call_arg (call, 0),
1129 return refs_may_alias_p_1 (&dref, ref, false);
1131 /* The following builtins do not read from memory. */
1133 case BUILT_IN_MALLOC:
1134 case BUILT_IN_CALLOC:
1135 case BUILT_IN_MEMSET:
1136 case BUILT_IN_FREXP:
1137 case BUILT_IN_FREXPF:
1138 case BUILT_IN_FREXPL:
1139 case BUILT_IN_GAMMA_R:
1140 case BUILT_IN_GAMMAF_R:
1141 case BUILT_IN_GAMMAL_R:
1142 case BUILT_IN_LGAMMA_R:
1143 case BUILT_IN_LGAMMAF_R:
1144 case BUILT_IN_LGAMMAL_R:
1146 case BUILT_IN_MODFF:
1147 case BUILT_IN_MODFL:
1148 case BUILT_IN_REMQUO:
1149 case BUILT_IN_REMQUOF:
1150 case BUILT_IN_REMQUOL:
1151 case BUILT_IN_SINCOS:
1152 case BUILT_IN_SINCOSF:
1153 case BUILT_IN_SINCOSL:
1157 /* Fallthru to general call handling. */;
1160 /* Check if base is a global static variable that is not read
1162 if (TREE_CODE (base) == VAR_DECL
1163 && TREE_STATIC (base))
1167 if (callee != NULL_TREE
1169 = ipa_reference_get_not_read_global (cgraph_node (callee)))
1170 && bitmap_bit_p (not_read, DECL_UID (base)))
1174 /* Check if the base variable is call-used. */
1177 if (pt_solution_includes (gimple_call_use_set (call), base))
1180 else if ((INDIRECT_REF_P (base)
1181 || TREE_CODE (base) == MEM_REF)
1182 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1184 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1188 if (pt_solutions_intersect (gimple_call_use_set (call), &pi->pt))
1194 /* Inspect call arguments for passed-by-value aliases. */
1196 for (i = 0; i < gimple_call_num_args (call); ++i)
1198 tree op = gimple_call_arg (call, i);
1199 int flags = gimple_call_arg_flags (call, i);
1201 if (flags & EAF_UNUSED)
1204 if (TREE_CODE (op) == WITH_SIZE_EXPR)
1205 op = TREE_OPERAND (op, 0);
1207 if (TREE_CODE (op) != SSA_NAME
1208 && !is_gimple_min_invariant (op))
1211 ao_ref_init (&r, op);
1212 if (refs_may_alias_p_1 (&r, ref, true))
1221 ref_maybe_used_by_call_p (gimple call, tree ref)
1225 ao_ref_init (&r, ref);
1226 res = ref_maybe_used_by_call_p_1 (call, &r);
1228 ++alias_stats.ref_maybe_used_by_call_p_may_alias;
1230 ++alias_stats.ref_maybe_used_by_call_p_no_alias;
1235 /* If the statement STMT may use the memory reference REF return
1236 true, otherwise return false. */
1239 ref_maybe_used_by_stmt_p (gimple stmt, tree ref)
1241 if (is_gimple_assign (stmt))
1245 /* All memory assign statements are single. */
1246 if (!gimple_assign_single_p (stmt))
1249 rhs = gimple_assign_rhs1 (stmt);
1250 if (is_gimple_reg (rhs)
1251 || is_gimple_min_invariant (rhs)
1252 || gimple_assign_rhs_code (stmt) == CONSTRUCTOR)
1255 return refs_may_alias_p (rhs, ref);
1257 else if (is_gimple_call (stmt))
1258 return ref_maybe_used_by_call_p (stmt, ref);
1263 /* If the call in statement CALL may clobber the memory reference REF
1264 return true, otherwise return false. */
1267 call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
1272 /* If the call is pure or const it cannot clobber anything. */
1273 if (gimple_call_flags (call)
1274 & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS))
1277 base = ao_ref_base (ref);
1281 if (TREE_CODE (base) == SSA_NAME
1282 || CONSTANT_CLASS_P (base))
1285 /* If the reference is based on a decl that is not aliased the call
1286 cannot possibly clobber it. */
1288 && !may_be_aliased (base)
1289 /* But local non-readonly statics can be modified through recursion
1290 or the call may implement a threading barrier which we must
1291 treat as may-def. */
1292 && (TREE_READONLY (base)
1293 || !is_global_var (base)))
1296 callee = gimple_call_fndecl (call);
1298 /* Handle those builtin functions explicitly that do not act as
1299 escape points. See tree-ssa-structalias.c:find_func_aliases
1300 for the list of builtins we might need to handle here. */
1301 if (callee != NULL_TREE
1302 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1303 switch (DECL_FUNCTION_CODE (callee))
1305 /* All the following functions clobber memory pointed to by
1306 their first argument. */
1307 case BUILT_IN_STRCPY:
1308 case BUILT_IN_STRNCPY:
1309 case BUILT_IN_MEMCPY:
1310 case BUILT_IN_MEMMOVE:
1311 case BUILT_IN_MEMPCPY:
1312 case BUILT_IN_STPCPY:
1313 case BUILT_IN_STPNCPY:
1314 case BUILT_IN_STRCAT:
1315 case BUILT_IN_STRNCAT:
1316 case BUILT_IN_MEMSET:
1319 tree size = NULL_TREE;
1320 if (gimple_call_num_args (call) == 3)
1321 size = gimple_call_arg (call, 2);
1322 ao_ref_init_from_ptr_and_size (&dref,
1323 gimple_call_arg (call, 0),
1325 return refs_may_alias_p_1 (&dref, ref, false);
1327 case BUILT_IN_BCOPY:
1330 tree size = gimple_call_arg (call, 2);
1331 ao_ref_init_from_ptr_and_size (&dref,
1332 gimple_call_arg (call, 1),
1334 return refs_may_alias_p_1 (&dref, ref, false);
1336 /* Allocating memory does not have any side-effects apart from
1337 being the definition point for the pointer. */
1338 case BUILT_IN_MALLOC:
1339 case BUILT_IN_CALLOC:
1340 /* Unix98 specifies that errno is set on allocation failure.
1341 Until we properly can track the errno location assume it
1342 is not a local decl but external or anonymous storage in
1343 a different translation unit. Also assume it is of
1344 type int as required by the standard. */
1346 && TREE_TYPE (base) == integer_type_node)
1348 struct ptr_info_def *pi;
1350 && !TREE_STATIC (base))
1352 else if ((INDIRECT_REF_P (base)
1353 || TREE_CODE (base) == MEM_REF)
1354 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME
1355 && (pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0))))
1356 return pi->pt.anything || pi->pt.nonlocal;
1359 /* Freeing memory kills the pointed-to memory. More importantly
1360 the call has to serve as a barrier for moving loads and stores
1364 tree ptr = gimple_call_arg (call, 0);
1365 return ptr_deref_may_alias_ref_p_1 (ptr, ref);
1367 case BUILT_IN_GAMMA_R:
1368 case BUILT_IN_GAMMAF_R:
1369 case BUILT_IN_GAMMAL_R:
1370 case BUILT_IN_LGAMMA_R:
1371 case BUILT_IN_LGAMMAF_R:
1372 case BUILT_IN_LGAMMAL_R:
1374 tree out = gimple_call_arg (call, 1);
1375 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1377 if (flag_errno_math)
1381 case BUILT_IN_FREXP:
1382 case BUILT_IN_FREXPF:
1383 case BUILT_IN_FREXPL:
1385 case BUILT_IN_MODFF:
1386 case BUILT_IN_MODFL:
1388 tree out = gimple_call_arg (call, 1);
1389 return ptr_deref_may_alias_ref_p_1 (out, ref);
1391 case BUILT_IN_REMQUO:
1392 case BUILT_IN_REMQUOF:
1393 case BUILT_IN_REMQUOL:
1395 tree out = gimple_call_arg (call, 2);
1396 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1398 if (flag_errno_math)
1402 case BUILT_IN_SINCOS:
1403 case BUILT_IN_SINCOSF:
1404 case BUILT_IN_SINCOSL:
1406 tree sin = gimple_call_arg (call, 1);
1407 tree cos = gimple_call_arg (call, 2);
1408 return (ptr_deref_may_alias_ref_p_1 (sin, ref)
1409 || ptr_deref_may_alias_ref_p_1 (cos, ref));
1412 /* Fallthru to general call handling. */;
1415 /* Check if base is a global static variable that is not written
1417 if (callee != NULL_TREE
1418 && TREE_CODE (base) == VAR_DECL
1419 && TREE_STATIC (base))
1424 = ipa_reference_get_not_written_global (cgraph_node (callee)))
1425 && bitmap_bit_p (not_written, DECL_UID (base)))
1429 /* Check if the base variable is call-clobbered. */
1431 return pt_solution_includes (gimple_call_clobber_set (call), base);
1432 else if ((INDIRECT_REF_P (base)
1433 || TREE_CODE (base) == MEM_REF)
1434 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1436 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1440 return pt_solutions_intersect (gimple_call_clobber_set (call), &pi->pt);
1446 /* If the call in statement CALL may clobber the memory reference REF
1447 return true, otherwise return false. */
1450 call_may_clobber_ref_p (gimple call, tree ref)
1454 ao_ref_init (&r, ref);
1455 res = call_may_clobber_ref_p_1 (call, &r);
1457 ++alias_stats.call_may_clobber_ref_p_may_alias;
1459 ++alias_stats.call_may_clobber_ref_p_no_alias;
1464 /* If the statement STMT may clobber the memory reference REF return true,
1465 otherwise return false. */
1468 stmt_may_clobber_ref_p_1 (gimple stmt, ao_ref *ref)
1470 if (is_gimple_call (stmt))
1472 tree lhs = gimple_call_lhs (stmt);
1474 && !is_gimple_reg (lhs))
1477 ao_ref_init (&r, lhs);
1478 if (refs_may_alias_p_1 (ref, &r, true))
1482 return call_may_clobber_ref_p_1 (stmt, ref);
1484 else if (gimple_assign_single_p (stmt))
1486 tree lhs = gimple_assign_lhs (stmt);
1487 if (!is_gimple_reg (lhs))
1490 ao_ref_init (&r, gimple_assign_lhs (stmt));
1491 return refs_may_alias_p_1 (ref, &r, true);
1494 else if (gimple_code (stmt) == GIMPLE_ASM)
1501 stmt_may_clobber_ref_p (gimple stmt, tree ref)
1504 ao_ref_init (&r, ref);
1505 return stmt_may_clobber_ref_p_1 (stmt, &r);
1509 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand
1510 TARGET or a statement clobbering the memory reference REF in which
1511 case false is returned. The walk starts with VUSE, one argument of PHI. */
1514 maybe_skip_until (gimple phi, tree target, ao_ref *ref,
1515 tree vuse, bitmap *visited)
1518 *visited = BITMAP_ALLOC (NULL);
1520 bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi)));
1522 /* Walk until we hit the target. */
1523 while (vuse != target)
1525 gimple def_stmt = SSA_NAME_DEF_STMT (vuse);
1526 /* Recurse for PHI nodes. */
1527 if (gimple_code (def_stmt) == GIMPLE_PHI)
1529 /* An already visited PHI node ends the walk successfully. */
1530 if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt))))
1532 vuse = get_continuation_for_phi (def_stmt, ref, visited);
1537 /* A clobbering statement or the end of the IL ends it failing. */
1538 else if (gimple_nop_p (def_stmt)
1539 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1541 vuse = gimple_vuse (def_stmt);
1546 /* Starting from a PHI node for the virtual operand of the memory reference
1547 REF find a continuation virtual operand that allows to continue walking
1548 statements dominating PHI skipping only statements that cannot possibly
1549 clobber REF. Returns NULL_TREE if no suitable virtual operand can
1553 get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited)
1555 unsigned nargs = gimple_phi_num_args (phi);
1557 /* Through a single-argument PHI we can simply look through. */
1559 return PHI_ARG_DEF (phi, 0);
1561 /* For two arguments try to skip non-aliasing code until we hit
1562 the phi argument definition that dominates the other one. */
1565 tree arg0 = PHI_ARG_DEF (phi, 0);
1566 tree arg1 = PHI_ARG_DEF (phi, 1);
1567 gimple def0 = SSA_NAME_DEF_STMT (arg0);
1568 gimple def1 = SSA_NAME_DEF_STMT (arg1);
1573 else if (gimple_nop_p (def0)
1574 || (!gimple_nop_p (def1)
1575 && dominated_by_p (CDI_DOMINATORS,
1576 gimple_bb (def1), gimple_bb (def0))))
1578 if (maybe_skip_until (phi, arg0, ref, arg1, visited))
1581 else if (gimple_nop_p (def1)
1582 || dominated_by_p (CDI_DOMINATORS,
1583 gimple_bb (def0), gimple_bb (def1)))
1585 if (maybe_skip_until (phi, arg1, ref, arg0, visited))
1588 /* Special case of a diamond:
1590 goto (cond) ? L1 : L2
1591 L1: store1 = ... #MEM_2 = vuse(MEM_1)
1593 L2: store2 = ... #MEM_3 = vuse(MEM_1)
1594 L3: MEM_4 = PHI<MEM_2, MEM_3>
1595 We were called with the PHI at L3, MEM_2 and MEM_3 don't
1596 dominate each other, but still we can easily skip this PHI node
1597 if we recognize that the vuse MEM operand is the same for both,
1598 and that we can skip both statements (they don't clobber us).
1599 This is still linear. Don't use maybe_skip_until, that might
1600 potentially be slow. */
1601 else if ((common_vuse = gimple_vuse (def0))
1602 && common_vuse == gimple_vuse (def1))
1604 if (!stmt_may_clobber_ref_p_1 (def0, ref)
1605 && !stmt_may_clobber_ref_p_1 (def1, ref))
1613 /* Based on the memory reference REF and its virtual use VUSE call
1614 WALKER for each virtual use that is equivalent to VUSE, including VUSE
1615 itself. That is, for each virtual use for which its defining statement
1616 does not clobber REF.
1618 WALKER is called with REF, the current virtual use and DATA. If
1619 WALKER returns non-NULL the walk stops and its result is returned.
1620 At the end of a non-successful walk NULL is returned.
1622 TRANSLATE if non-NULL is called with a pointer to REF, the virtual
1623 use which definition is a statement that may clobber REF and DATA.
1624 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
1625 If TRANSLATE returns non-NULL the walk stops and its result is returned.
1626 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
1627 to adjust REF and *DATA to make that valid.
1629 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
1632 walk_non_aliased_vuses (ao_ref *ref, tree vuse,
1633 void *(*walker)(ao_ref *, tree, void *),
1634 void *(*translate)(ao_ref *, tree, void *), void *data)
1636 bitmap visited = NULL;
1639 timevar_push (TV_ALIAS_STMT_WALK);
1645 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1646 res = (*walker) (ref, vuse, data);
1650 def_stmt = SSA_NAME_DEF_STMT (vuse);
1651 if (gimple_nop_p (def_stmt))
1653 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1654 vuse = get_continuation_for_phi (def_stmt, ref, &visited);
1657 if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
1661 res = (*translate) (ref, vuse, data);
1662 /* Failed lookup and translation. */
1663 if (res == (void *)-1)
1668 /* Lookup succeeded. */
1669 else if (res != NULL)
1671 /* Translation succeeded, continue walking. */
1673 vuse = gimple_vuse (def_stmt);
1679 BITMAP_FREE (visited);
1681 timevar_pop (TV_ALIAS_STMT_WALK);
1687 /* Based on the memory reference REF call WALKER for each vdef which
1688 defining statement may clobber REF, starting with VDEF. If REF
1689 is NULL_TREE, each defining statement is visited.
1691 WALKER is called with REF, the current vdef and DATA. If WALKER
1692 returns true the walk is stopped, otherwise it continues.
1694 At PHI nodes walk_aliased_vdefs forks into one walk for reach
1695 PHI argument (but only one walk continues on merge points), the
1696 return value is true if any of the walks was successful.
1698 The function returns the number of statements walked. */
1701 walk_aliased_vdefs_1 (ao_ref *ref, tree vdef,
1702 bool (*walker)(ao_ref *, tree, void *), void *data,
1703 bitmap *visited, unsigned int cnt)
1707 gimple def_stmt = SSA_NAME_DEF_STMT (vdef);
1710 && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef)))
1713 if (gimple_nop_p (def_stmt))
1715 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1719 *visited = BITMAP_ALLOC (NULL);
1720 for (i = 0; i < gimple_phi_num_args (def_stmt); ++i)
1721 cnt += walk_aliased_vdefs_1 (ref, gimple_phi_arg_def (def_stmt, i),
1722 walker, data, visited, 0);
1726 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1729 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1730 && (*walker) (ref, vdef, data))
1733 vdef = gimple_vuse (def_stmt);
1739 walk_aliased_vdefs (ao_ref *ref, tree vdef,
1740 bool (*walker)(ao_ref *, tree, void *), void *data,
1743 bitmap local_visited = NULL;
1746 timevar_push (TV_ALIAS_STMT_WALK);
1748 ret = walk_aliased_vdefs_1 (ref, vdef, walker, data,
1749 visited ? visited : &local_visited, 0);
1751 BITMAP_FREE (local_visited);
1753 timevar_pop (TV_ALIAS_STMT_WALK);