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)
671 HOST_WIDE_INT offset1p = offset1, offset2p = offset2;
673 ptr1 = TREE_OPERAND (base1, 0);
675 /* The offset embedded in MEM_REFs can be negative. Bias them
676 so that the resulting offset adjustment is positive. */
677 if (TREE_CODE (base1) == MEM_REF
678 || TREE_CODE (base1) == TARGET_MEM_REF)
680 double_int moff = mem_ref_offset (base1);
681 moff = double_int_lshift (moff,
683 ? 3 : exact_log2 (BITS_PER_UNIT),
684 HOST_BITS_PER_DOUBLE_INT, true);
685 if (double_int_negative_p (moff))
686 offset2p += double_int_neg (moff).low;
688 offset1p += moff.low;
691 /* If only one reference is based on a variable, they cannot alias if
692 the pointer access is beyond the extent of the variable access.
693 (the pointer base cannot validly point to an offset less than zero
695 They also cannot alias if the pointer may not point to the decl. */
696 if ((TREE_CODE (base1) != TARGET_MEM_REF
697 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
698 && !ranges_overlap_p (MAX (0, offset1p), -1, offset2p, max_size2))
700 if (!ptr_deref_may_alias_decl_p (ptr1, base2))
703 /* Disambiguations that rely on strict aliasing rules follow. */
704 if (!flag_strict_aliasing || !tbaa_p)
707 if (TREE_CODE (base1) == MEM_REF)
708 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
709 else if (TREE_CODE (base1) == TARGET_MEM_REF)
710 ptrtype1 = TREE_TYPE (TMR_OFFSET (base1));
712 ptrtype1 = TREE_TYPE (ptr1);
714 /* If the alias set for a pointer access is zero all bets are off. */
715 if (base1_alias_set == -1)
716 base1_alias_set = get_deref_alias_set (ptrtype1);
717 if (base1_alias_set == 0)
719 if (base2_alias_set == -1)
720 base2_alias_set = get_alias_set (base2);
722 /* If both references are through the same type, they do not alias
723 if the accesses do not overlap. This does extra disambiguation
724 for mixed/pointer accesses but requires strict aliasing.
725 For MEM_REFs we require that the component-ref offset we computed
726 is relative to the start of the type which we ensure by
727 comparing rvalue and access type and disregarding the constant
729 if ((TREE_CODE (base1) != TARGET_MEM_REF
730 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
731 && (TREE_CODE (base1) != MEM_REF
732 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
733 && same_type_for_tbaa (TREE_TYPE (ptrtype1), TREE_TYPE (base2)) == 1)
734 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
736 /* When we are trying to disambiguate an access with a pointer dereference
737 as base versus one with a decl as base we can use both the size
738 of the decl and its dynamic type for extra disambiguation.
739 ??? We do not know anything about the dynamic type of the decl
740 other than that its alias-set contains base2_alias_set as a subset
741 which does not help us here. */
742 /* As we know nothing useful about the dynamic type of the decl just
743 use the usual conflict check rather than a subset test.
744 ??? We could introduce -fvery-strict-aliasing when the language
745 does not allow decls to have a dynamic type that differs from their
746 static type. Then we can check
747 !alias_set_subset_of (base1_alias_set, base2_alias_set) instead. */
748 if (base1_alias_set != base2_alias_set
749 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
751 /* If the size of the access relevant for TBAA through the pointer
752 is bigger than the size of the decl we can't possibly access the
753 decl via that pointer. */
754 if (DECL_SIZE (base2) && COMPLETE_TYPE_P (TREE_TYPE (ptrtype1))
755 && TREE_CODE (DECL_SIZE (base2)) == INTEGER_CST
756 && TREE_CODE (TYPE_SIZE (TREE_TYPE (ptrtype1))) == INTEGER_CST
757 /* ??? This in turn may run afoul when a decl of type T which is
758 a member of union type U is accessed through a pointer to
759 type U and sizeof T is smaller than sizeof U. */
760 && TREE_CODE (TREE_TYPE (ptrtype1)) != UNION_TYPE
761 && TREE_CODE (TREE_TYPE (ptrtype1)) != QUAL_UNION_TYPE
762 && tree_int_cst_lt (DECL_SIZE (base2), TYPE_SIZE (TREE_TYPE (ptrtype1))))
765 /* Do access-path based disambiguation. */
767 && handled_component_p (ref1)
768 && handled_component_p (ref2)
769 && TREE_CODE (base1) != TARGET_MEM_REF
770 && (TREE_CODE (base1) != MEM_REF
771 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1))
772 return aliasing_component_refs_p (ref1, TREE_TYPE (ptrtype1),
773 ref1_alias_set, base1_alias_set,
775 ref2, TREE_TYPE (base2),
776 ref2_alias_set, base2_alias_set,
777 offset2, max_size2, true);
782 /* Return true if two indirect references based on *PTR1
783 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
784 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have
785 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
786 in which case they are computed on-demand. REF1 and REF2
787 if non-NULL are the complete memory reference trees. */
790 indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
791 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
792 alias_set_type ref1_alias_set,
793 alias_set_type base1_alias_set,
794 tree ref2 ATTRIBUTE_UNUSED, tree base2,
795 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
796 alias_set_type ref2_alias_set,
797 alias_set_type base2_alias_set, bool tbaa_p)
801 tree ptrtype1, ptrtype2;
803 ptr1 = TREE_OPERAND (base1, 0);
804 ptr2 = TREE_OPERAND (base2, 0);
806 /* If both bases are based on pointers they cannot alias if they may not
807 point to the same memory object or if they point to the same object
808 and the accesses do not overlap. */
809 if ((!cfun || gimple_in_ssa_p (cfun))
810 && operand_equal_p (ptr1, ptr2, 0)
811 && (((TREE_CODE (base1) != TARGET_MEM_REF
812 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
813 && (TREE_CODE (base2) != TARGET_MEM_REF
814 || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2))))
815 || (TREE_CODE (base1) == TARGET_MEM_REF
816 && TREE_CODE (base2) == TARGET_MEM_REF
817 && (TMR_STEP (base1) == TMR_STEP (base2)
818 || (TMR_STEP (base1) && TMR_STEP (base2)
819 && operand_equal_p (TMR_STEP (base1),
820 TMR_STEP (base2), 0)))
821 && (TMR_INDEX (base1) == TMR_INDEX (base2)
822 || (TMR_INDEX (base1) && TMR_INDEX (base2)
823 && operand_equal_p (TMR_INDEX (base1),
824 TMR_INDEX (base2), 0)))
825 && (TMR_INDEX2 (base1) == TMR_INDEX2 (base2)
826 || (TMR_INDEX2 (base1) && TMR_INDEX2 (base2)
827 && operand_equal_p (TMR_INDEX2 (base1),
828 TMR_INDEX2 (base2), 0))))))
830 /* The offset embedded in MEM_REFs can be negative. Bias them
831 so that the resulting offset adjustment is positive. */
832 if (TREE_CODE (base1) == MEM_REF
833 || TREE_CODE (base1) == TARGET_MEM_REF)
835 double_int moff = mem_ref_offset (base1);
836 moff = double_int_lshift (moff,
838 ? 3 : exact_log2 (BITS_PER_UNIT),
839 HOST_BITS_PER_DOUBLE_INT, true);
840 if (double_int_negative_p (moff))
841 offset2 += double_int_neg (moff).low;
845 if (TREE_CODE (base2) == MEM_REF
846 || TREE_CODE (base2) == TARGET_MEM_REF)
848 double_int moff = mem_ref_offset (base2);
849 moff = double_int_lshift (moff,
851 ? 3 : exact_log2 (BITS_PER_UNIT),
852 HOST_BITS_PER_DOUBLE_INT, true);
853 if (double_int_negative_p (moff))
854 offset1 += double_int_neg (moff).low;
858 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
860 if (!ptr_derefs_may_alias_p (ptr1, ptr2))
863 /* Disambiguations that rely on strict aliasing rules follow. */
864 if (!flag_strict_aliasing || !tbaa_p)
867 if (TREE_CODE (base1) == MEM_REF)
868 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
869 else if (TREE_CODE (base1) == TARGET_MEM_REF)
870 ptrtype1 = TREE_TYPE (TMR_OFFSET (base1));
872 ptrtype1 = TREE_TYPE (ptr1);
873 if (TREE_CODE (base2) == MEM_REF)
874 ptrtype2 = TREE_TYPE (TREE_OPERAND (base2, 1));
875 else if (TREE_CODE (base2) == TARGET_MEM_REF)
876 ptrtype2 = TREE_TYPE (TMR_OFFSET (base2));
878 ptrtype2 = TREE_TYPE (ptr2);
880 /* If the alias set for a pointer access is zero all bets are off. */
881 if (base1_alias_set == -1)
882 base1_alias_set = get_deref_alias_set (ptrtype1);
883 if (base1_alias_set == 0)
885 if (base2_alias_set == -1)
886 base2_alias_set = get_deref_alias_set (ptrtype2);
887 if (base2_alias_set == 0)
890 /* If both references are through the same type, they do not alias
891 if the accesses do not overlap. This does extra disambiguation
892 for mixed/pointer accesses but requires strict aliasing. */
893 if ((TREE_CODE (base1) != TARGET_MEM_REF || !TMR_INDEX (base1))
894 && (TREE_CODE (base2) != TARGET_MEM_REF || !TMR_INDEX (base2))
895 && (TREE_CODE (base1) != MEM_REF
896 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
897 && (TREE_CODE (base2) != MEM_REF
898 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1)
899 && same_type_for_tbaa (TREE_TYPE (ptrtype1),
900 TREE_TYPE (ptrtype2)) == 1)
901 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
903 /* Do type-based disambiguation. */
904 if (base1_alias_set != base2_alias_set
905 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
908 /* Do access-path based disambiguation. */
910 && handled_component_p (ref1)
911 && handled_component_p (ref2)
912 && TREE_CODE (base1) != TARGET_MEM_REF
913 && TREE_CODE (base2) != TARGET_MEM_REF
914 && (TREE_CODE (base1) != MEM_REF
915 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
916 && (TREE_CODE (base2) != MEM_REF
917 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1))
918 return aliasing_component_refs_p (ref1, TREE_TYPE (ptrtype1),
919 ref1_alias_set, base1_alias_set,
921 ref2, TREE_TYPE (ptrtype2),
922 ref2_alias_set, base2_alias_set,
923 offset2, max_size2, false);
928 /* Return true, if the two memory references REF1 and REF2 may alias. */
931 refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
934 HOST_WIDE_INT offset1 = 0, offset2 = 0;
935 HOST_WIDE_INT max_size1 = -1, max_size2 = -1;
936 bool var1_p, var2_p, ind1_p, ind2_p;
938 gcc_checking_assert ((!ref1->ref
939 || TREE_CODE (ref1->ref) == SSA_NAME
940 || DECL_P (ref1->ref)
941 || handled_component_p (ref1->ref)
942 || INDIRECT_REF_P (ref1->ref)
943 || TREE_CODE (ref1->ref) == MEM_REF
944 || TREE_CODE (ref1->ref) == TARGET_MEM_REF)
946 || TREE_CODE (ref2->ref) == SSA_NAME
947 || DECL_P (ref2->ref)
948 || handled_component_p (ref2->ref)
949 || INDIRECT_REF_P (ref2->ref)
950 || TREE_CODE (ref2->ref) == MEM_REF
951 || TREE_CODE (ref2->ref) == TARGET_MEM_REF));
953 /* Decompose the references into their base objects and the access. */
954 base1 = ao_ref_base (ref1);
955 offset1 = ref1->offset;
956 max_size1 = ref1->max_size;
957 base2 = ao_ref_base (ref2);
958 offset2 = ref2->offset;
959 max_size2 = ref2->max_size;
961 /* We can end up with registers or constants as bases for example from
962 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
963 which is seen as a struct copy. */
964 if (TREE_CODE (base1) == SSA_NAME
965 || TREE_CODE (base2) == SSA_NAME
966 || TREE_CODE (base1) == CONST_DECL
967 || TREE_CODE (base2) == CONST_DECL
968 || is_gimple_min_invariant (base1)
969 || is_gimple_min_invariant (base2))
972 /* We can end up refering to code via function and label decls.
973 As we likely do not properly track code aliases conservatively
975 if (TREE_CODE (base1) == FUNCTION_DECL
976 || TREE_CODE (base2) == FUNCTION_DECL
977 || TREE_CODE (base1) == LABEL_DECL
978 || TREE_CODE (base2) == LABEL_DECL)
981 /* Defer to simple offset based disambiguation if we have
982 references based on two decls. Do this before defering to
983 TBAA to handle must-alias cases in conformance with the
984 GCC extension of allowing type-punning through unions. */
985 var1_p = SSA_VAR_P (base1);
986 var2_p = SSA_VAR_P (base2);
987 if (var1_p && var2_p)
988 return decl_refs_may_alias_p (base1, offset1, max_size1,
989 base2, offset2, max_size2);
991 ind1_p = (INDIRECT_REF_P (base1)
992 || (TREE_CODE (base1) == MEM_REF)
993 || (TREE_CODE (base1) == TARGET_MEM_REF));
994 ind2_p = (INDIRECT_REF_P (base2)
995 || (TREE_CODE (base2) == MEM_REF)
996 || (TREE_CODE (base2) == TARGET_MEM_REF));
998 /* Canonicalize the pointer-vs-decl case. */
999 if (ind1_p && var2_p)
1004 tmp1 = offset1; offset1 = offset2; offset2 = tmp1;
1005 tmp1 = max_size1; max_size1 = max_size2; max_size2 = tmp1;
1006 tmp2 = base1; base1 = base2; base2 = tmp2;
1007 tmp3 = ref1; ref1 = ref2; ref2 = tmp3;
1014 /* First defer to TBAA if possible. */
1016 && flag_strict_aliasing
1017 && !alias_sets_conflict_p (ao_ref_alias_set (ref1),
1018 ao_ref_alias_set (ref2)))
1021 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */
1022 if (var1_p && ind2_p)
1023 return indirect_ref_may_alias_decl_p (ref2->ref, base2,
1025 ao_ref_alias_set (ref2), -1,
1028 ao_ref_alias_set (ref1),
1029 ao_ref_base_alias_set (ref1),
1031 else if (ind1_p && ind2_p)
1032 return indirect_refs_may_alias_p (ref1->ref, base1,
1034 ao_ref_alias_set (ref1), -1,
1037 ao_ref_alias_set (ref2), -1,
1044 refs_may_alias_p (tree ref1, tree ref2)
1048 ao_ref_init (&r1, ref1);
1049 ao_ref_init (&r2, ref2);
1050 res = refs_may_alias_p_1 (&r1, &r2, true);
1052 ++alias_stats.refs_may_alias_p_may_alias;
1054 ++alias_stats.refs_may_alias_p_no_alias;
1058 /* Returns true if there is a anti-dependence for the STORE that
1059 executes after the LOAD. */
1062 refs_anti_dependent_p (tree load, tree store)
1065 ao_ref_init (&r1, load);
1066 ao_ref_init (&r2, store);
1067 return refs_may_alias_p_1 (&r1, &r2, false);
1070 /* Returns true if there is a output dependence for the stores
1071 STORE1 and STORE2. */
1074 refs_output_dependent_p (tree store1, tree store2)
1077 ao_ref_init (&r1, store1);
1078 ao_ref_init (&r2, store2);
1079 return refs_may_alias_p_1 (&r1, &r2, false);
1082 /* If the call CALL may use the memory reference REF return true,
1083 otherwise return false. */
1086 ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
1090 int flags = gimple_call_flags (call);
1092 /* Const functions without a static chain do not implicitly use memory. */
1093 if (!gimple_call_chain (call)
1094 && (flags & (ECF_CONST|ECF_NOVOPS)))
1097 base = ao_ref_base (ref);
1101 /* If the reference is based on a decl that is not aliased the call
1102 cannot possibly use it. */
1104 && !may_be_aliased (base)
1105 /* But local statics can be used through recursion. */
1106 && !is_global_var (base))
1109 callee = gimple_call_fndecl (call);
1111 /* Handle those builtin functions explicitly that do not act as
1112 escape points. See tree-ssa-structalias.c:find_func_aliases
1113 for the list of builtins we might need to handle here. */
1114 if (callee != NULL_TREE
1115 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1116 switch (DECL_FUNCTION_CODE (callee))
1118 /* All the following functions clobber memory pointed to by
1119 their first argument. */
1120 case BUILT_IN_STRCPY:
1121 case BUILT_IN_STRNCPY:
1122 case BUILT_IN_MEMCPY:
1123 case BUILT_IN_MEMMOVE:
1124 case BUILT_IN_MEMPCPY:
1125 case BUILT_IN_STPCPY:
1126 case BUILT_IN_STPNCPY:
1127 case BUILT_IN_STRCAT:
1128 case BUILT_IN_STRNCAT:
1131 tree size = NULL_TREE;
1132 if (gimple_call_num_args (call) == 3)
1133 size = gimple_call_arg (call, 2);
1134 ao_ref_init_from_ptr_and_size (&dref,
1135 gimple_call_arg (call, 1),
1137 return refs_may_alias_p_1 (&dref, ref, false);
1139 case BUILT_IN_BCOPY:
1142 tree size = gimple_call_arg (call, 2);
1143 ao_ref_init_from_ptr_and_size (&dref,
1144 gimple_call_arg (call, 0),
1146 return refs_may_alias_p_1 (&dref, ref, false);
1148 /* The following builtins do not read from memory. */
1150 case BUILT_IN_MALLOC:
1151 case BUILT_IN_CALLOC:
1152 case BUILT_IN_MEMSET:
1153 case BUILT_IN_FREXP:
1154 case BUILT_IN_FREXPF:
1155 case BUILT_IN_FREXPL:
1156 case BUILT_IN_GAMMA_R:
1157 case BUILT_IN_GAMMAF_R:
1158 case BUILT_IN_GAMMAL_R:
1159 case BUILT_IN_LGAMMA_R:
1160 case BUILT_IN_LGAMMAF_R:
1161 case BUILT_IN_LGAMMAL_R:
1163 case BUILT_IN_MODFF:
1164 case BUILT_IN_MODFL:
1165 case BUILT_IN_REMQUO:
1166 case BUILT_IN_REMQUOF:
1167 case BUILT_IN_REMQUOL:
1168 case BUILT_IN_SINCOS:
1169 case BUILT_IN_SINCOSF:
1170 case BUILT_IN_SINCOSL:
1174 /* Fallthru to general call handling. */;
1177 /* Check if base is a global static variable that is not read
1179 if (TREE_CODE (base) == VAR_DECL
1180 && TREE_STATIC (base))
1184 if (callee != NULL_TREE
1186 = ipa_reference_get_not_read_global (cgraph_node (callee)))
1187 && bitmap_bit_p (not_read, DECL_UID (base)))
1191 /* Check if the base variable is call-used. */
1194 if (pt_solution_includes (gimple_call_use_set (call), base))
1197 else if ((INDIRECT_REF_P (base)
1198 || TREE_CODE (base) == MEM_REF)
1199 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1201 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1205 if (pt_solutions_intersect (gimple_call_use_set (call), &pi->pt))
1211 /* Inspect call arguments for passed-by-value aliases. */
1213 for (i = 0; i < gimple_call_num_args (call); ++i)
1215 tree op = gimple_call_arg (call, i);
1216 int flags = gimple_call_arg_flags (call, i);
1218 if (flags & EAF_UNUSED)
1221 if (TREE_CODE (op) == WITH_SIZE_EXPR)
1222 op = TREE_OPERAND (op, 0);
1224 if (TREE_CODE (op) != SSA_NAME
1225 && !is_gimple_min_invariant (op))
1228 ao_ref_init (&r, op);
1229 if (refs_may_alias_p_1 (&r, ref, true))
1238 ref_maybe_used_by_call_p (gimple call, tree ref)
1242 ao_ref_init (&r, ref);
1243 res = ref_maybe_used_by_call_p_1 (call, &r);
1245 ++alias_stats.ref_maybe_used_by_call_p_may_alias;
1247 ++alias_stats.ref_maybe_used_by_call_p_no_alias;
1252 /* If the statement STMT may use the memory reference REF return
1253 true, otherwise return false. */
1256 ref_maybe_used_by_stmt_p (gimple stmt, tree ref)
1258 if (is_gimple_assign (stmt))
1262 /* All memory assign statements are single. */
1263 if (!gimple_assign_single_p (stmt))
1266 rhs = gimple_assign_rhs1 (stmt);
1267 if (is_gimple_reg (rhs)
1268 || is_gimple_min_invariant (rhs)
1269 || gimple_assign_rhs_code (stmt) == CONSTRUCTOR)
1272 return refs_may_alias_p (rhs, ref);
1274 else if (is_gimple_call (stmt))
1275 return ref_maybe_used_by_call_p (stmt, ref);
1280 /* If the call in statement CALL may clobber the memory reference REF
1281 return true, otherwise return false. */
1284 call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
1289 /* If the call is pure or const it cannot clobber anything. */
1290 if (gimple_call_flags (call)
1291 & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS))
1294 base = ao_ref_base (ref);
1298 if (TREE_CODE (base) == SSA_NAME
1299 || CONSTANT_CLASS_P (base))
1302 /* If the reference is based on a decl that is not aliased the call
1303 cannot possibly clobber it. */
1305 && !may_be_aliased (base)
1306 /* But local non-readonly statics can be modified through recursion
1307 or the call may implement a threading barrier which we must
1308 treat as may-def. */
1309 && (TREE_READONLY (base)
1310 || !is_global_var (base)))
1313 callee = gimple_call_fndecl (call);
1315 /* Handle those builtin functions explicitly that do not act as
1316 escape points. See tree-ssa-structalias.c:find_func_aliases
1317 for the list of builtins we might need to handle here. */
1318 if (callee != NULL_TREE
1319 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1320 switch (DECL_FUNCTION_CODE (callee))
1322 /* All the following functions clobber memory pointed to by
1323 their first argument. */
1324 case BUILT_IN_STRCPY:
1325 case BUILT_IN_STRNCPY:
1326 case BUILT_IN_MEMCPY:
1327 case BUILT_IN_MEMMOVE:
1328 case BUILT_IN_MEMPCPY:
1329 case BUILT_IN_STPCPY:
1330 case BUILT_IN_STPNCPY:
1331 case BUILT_IN_STRCAT:
1332 case BUILT_IN_STRNCAT:
1333 case BUILT_IN_MEMSET:
1336 tree size = NULL_TREE;
1337 if (gimple_call_num_args (call) == 3)
1338 size = gimple_call_arg (call, 2);
1339 ao_ref_init_from_ptr_and_size (&dref,
1340 gimple_call_arg (call, 0),
1342 return refs_may_alias_p_1 (&dref, ref, false);
1344 case BUILT_IN_BCOPY:
1347 tree size = gimple_call_arg (call, 2);
1348 ao_ref_init_from_ptr_and_size (&dref,
1349 gimple_call_arg (call, 1),
1351 return refs_may_alias_p_1 (&dref, ref, false);
1353 /* Allocating memory does not have any side-effects apart from
1354 being the definition point for the pointer. */
1355 case BUILT_IN_MALLOC:
1356 case BUILT_IN_CALLOC:
1357 /* Unix98 specifies that errno is set on allocation failure.
1358 Until we properly can track the errno location assume it
1359 is not a local decl but external or anonymous storage in
1360 a different translation unit. Also assume it is of
1361 type int as required by the standard. */
1363 && TREE_TYPE (base) == integer_type_node)
1365 struct ptr_info_def *pi;
1367 && !TREE_STATIC (base))
1369 else if ((INDIRECT_REF_P (base)
1370 || TREE_CODE (base) == MEM_REF)
1371 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME
1372 && (pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0))))
1373 return pi->pt.anything || pi->pt.nonlocal;
1376 /* Freeing memory kills the pointed-to memory. More importantly
1377 the call has to serve as a barrier for moving loads and stores
1381 tree ptr = gimple_call_arg (call, 0);
1382 return ptr_deref_may_alias_ref_p_1 (ptr, ref);
1384 case BUILT_IN_GAMMA_R:
1385 case BUILT_IN_GAMMAF_R:
1386 case BUILT_IN_GAMMAL_R:
1387 case BUILT_IN_LGAMMA_R:
1388 case BUILT_IN_LGAMMAF_R:
1389 case BUILT_IN_LGAMMAL_R:
1391 tree out = gimple_call_arg (call, 1);
1392 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1394 if (flag_errno_math)
1398 case BUILT_IN_FREXP:
1399 case BUILT_IN_FREXPF:
1400 case BUILT_IN_FREXPL:
1402 case BUILT_IN_MODFF:
1403 case BUILT_IN_MODFL:
1405 tree out = gimple_call_arg (call, 1);
1406 return ptr_deref_may_alias_ref_p_1 (out, ref);
1408 case BUILT_IN_REMQUO:
1409 case BUILT_IN_REMQUOF:
1410 case BUILT_IN_REMQUOL:
1412 tree out = gimple_call_arg (call, 2);
1413 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1415 if (flag_errno_math)
1419 case BUILT_IN_SINCOS:
1420 case BUILT_IN_SINCOSF:
1421 case BUILT_IN_SINCOSL:
1423 tree sin = gimple_call_arg (call, 1);
1424 tree cos = gimple_call_arg (call, 2);
1425 return (ptr_deref_may_alias_ref_p_1 (sin, ref)
1426 || ptr_deref_may_alias_ref_p_1 (cos, ref));
1429 /* Fallthru to general call handling. */;
1432 /* Check if base is a global static variable that is not written
1434 if (callee != NULL_TREE
1435 && TREE_CODE (base) == VAR_DECL
1436 && TREE_STATIC (base))
1441 = ipa_reference_get_not_written_global (cgraph_node (callee)))
1442 && bitmap_bit_p (not_written, DECL_UID (base)))
1446 /* Check if the base variable is call-clobbered. */
1448 return pt_solution_includes (gimple_call_clobber_set (call), base);
1449 else if ((INDIRECT_REF_P (base)
1450 || TREE_CODE (base) == MEM_REF)
1451 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1453 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1457 return pt_solutions_intersect (gimple_call_clobber_set (call), &pi->pt);
1463 /* If the call in statement CALL may clobber the memory reference REF
1464 return true, otherwise return false. */
1467 call_may_clobber_ref_p (gimple call, tree ref)
1471 ao_ref_init (&r, ref);
1472 res = call_may_clobber_ref_p_1 (call, &r);
1474 ++alias_stats.call_may_clobber_ref_p_may_alias;
1476 ++alias_stats.call_may_clobber_ref_p_no_alias;
1481 /* If the statement STMT may clobber the memory reference REF return true,
1482 otherwise return false. */
1485 stmt_may_clobber_ref_p_1 (gimple stmt, ao_ref *ref)
1487 if (is_gimple_call (stmt))
1489 tree lhs = gimple_call_lhs (stmt);
1491 && !is_gimple_reg (lhs))
1494 ao_ref_init (&r, lhs);
1495 if (refs_may_alias_p_1 (ref, &r, true))
1499 return call_may_clobber_ref_p_1 (stmt, ref);
1501 else if (gimple_assign_single_p (stmt))
1503 tree lhs = gimple_assign_lhs (stmt);
1504 if (!is_gimple_reg (lhs))
1507 ao_ref_init (&r, gimple_assign_lhs (stmt));
1508 return refs_may_alias_p_1 (ref, &r, true);
1511 else if (gimple_code (stmt) == GIMPLE_ASM)
1518 stmt_may_clobber_ref_p (gimple stmt, tree ref)
1521 ao_ref_init (&r, ref);
1522 return stmt_may_clobber_ref_p_1 (stmt, &r);
1526 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand
1527 TARGET or a statement clobbering the memory reference REF in which
1528 case false is returned. The walk starts with VUSE, one argument of PHI. */
1531 maybe_skip_until (gimple phi, tree target, ao_ref *ref,
1532 tree vuse, bitmap *visited)
1535 *visited = BITMAP_ALLOC (NULL);
1537 bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi)));
1539 /* Walk until we hit the target. */
1540 while (vuse != target)
1542 gimple def_stmt = SSA_NAME_DEF_STMT (vuse);
1543 /* Recurse for PHI nodes. */
1544 if (gimple_code (def_stmt) == GIMPLE_PHI)
1546 /* An already visited PHI node ends the walk successfully. */
1547 if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt))))
1549 vuse = get_continuation_for_phi (def_stmt, ref, visited);
1554 /* A clobbering statement or the end of the IL ends it failing. */
1555 else if (gimple_nop_p (def_stmt)
1556 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1558 vuse = gimple_vuse (def_stmt);
1563 /* Starting from a PHI node for the virtual operand of the memory reference
1564 REF find a continuation virtual operand that allows to continue walking
1565 statements dominating PHI skipping only statements that cannot possibly
1566 clobber REF. Returns NULL_TREE if no suitable virtual operand can
1570 get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited)
1572 unsigned nargs = gimple_phi_num_args (phi);
1574 /* Through a single-argument PHI we can simply look through. */
1576 return PHI_ARG_DEF (phi, 0);
1578 /* For two arguments try to skip non-aliasing code until we hit
1579 the phi argument definition that dominates the other one. */
1582 tree arg0 = PHI_ARG_DEF (phi, 0);
1583 tree arg1 = PHI_ARG_DEF (phi, 1);
1584 gimple def0 = SSA_NAME_DEF_STMT (arg0);
1585 gimple def1 = SSA_NAME_DEF_STMT (arg1);
1590 else if (gimple_nop_p (def0)
1591 || (!gimple_nop_p (def1)
1592 && dominated_by_p (CDI_DOMINATORS,
1593 gimple_bb (def1), gimple_bb (def0))))
1595 if (maybe_skip_until (phi, arg0, ref, arg1, visited))
1598 else if (gimple_nop_p (def1)
1599 || dominated_by_p (CDI_DOMINATORS,
1600 gimple_bb (def0), gimple_bb (def1)))
1602 if (maybe_skip_until (phi, arg1, ref, arg0, visited))
1605 /* Special case of a diamond:
1607 goto (cond) ? L1 : L2
1608 L1: store1 = ... #MEM_2 = vuse(MEM_1)
1610 L2: store2 = ... #MEM_3 = vuse(MEM_1)
1611 L3: MEM_4 = PHI<MEM_2, MEM_3>
1612 We were called with the PHI at L3, MEM_2 and MEM_3 don't
1613 dominate each other, but still we can easily skip this PHI node
1614 if we recognize that the vuse MEM operand is the same for both,
1615 and that we can skip both statements (they don't clobber us).
1616 This is still linear. Don't use maybe_skip_until, that might
1617 potentially be slow. */
1618 else if ((common_vuse = gimple_vuse (def0))
1619 && common_vuse == gimple_vuse (def1))
1621 if (!stmt_may_clobber_ref_p_1 (def0, ref)
1622 && !stmt_may_clobber_ref_p_1 (def1, ref))
1630 /* Based on the memory reference REF and its virtual use VUSE call
1631 WALKER for each virtual use that is equivalent to VUSE, including VUSE
1632 itself. That is, for each virtual use for which its defining statement
1633 does not clobber REF.
1635 WALKER is called with REF, the current virtual use and DATA. If
1636 WALKER returns non-NULL the walk stops and its result is returned.
1637 At the end of a non-successful walk NULL is returned.
1639 TRANSLATE if non-NULL is called with a pointer to REF, the virtual
1640 use which definition is a statement that may clobber REF and DATA.
1641 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
1642 If TRANSLATE returns non-NULL the walk stops and its result is returned.
1643 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
1644 to adjust REF and *DATA to make that valid.
1646 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
1649 walk_non_aliased_vuses (ao_ref *ref, tree vuse,
1650 void *(*walker)(ao_ref *, tree, void *),
1651 void *(*translate)(ao_ref *, tree, void *), void *data)
1653 bitmap visited = NULL;
1656 timevar_push (TV_ALIAS_STMT_WALK);
1662 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1663 res = (*walker) (ref, vuse, data);
1667 def_stmt = SSA_NAME_DEF_STMT (vuse);
1668 if (gimple_nop_p (def_stmt))
1670 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1671 vuse = get_continuation_for_phi (def_stmt, ref, &visited);
1674 if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
1678 res = (*translate) (ref, vuse, data);
1679 /* Failed lookup and translation. */
1680 if (res == (void *)-1)
1685 /* Lookup succeeded. */
1686 else if (res != NULL)
1688 /* Translation succeeded, continue walking. */
1690 vuse = gimple_vuse (def_stmt);
1696 BITMAP_FREE (visited);
1698 timevar_pop (TV_ALIAS_STMT_WALK);
1704 /* Based on the memory reference REF call WALKER for each vdef which
1705 defining statement may clobber REF, starting with VDEF. If REF
1706 is NULL_TREE, each defining statement is visited.
1708 WALKER is called with REF, the current vdef and DATA. If WALKER
1709 returns true the walk is stopped, otherwise it continues.
1711 At PHI nodes walk_aliased_vdefs forks into one walk for reach
1712 PHI argument (but only one walk continues on merge points), the
1713 return value is true if any of the walks was successful.
1715 The function returns the number of statements walked. */
1718 walk_aliased_vdefs_1 (ao_ref *ref, tree vdef,
1719 bool (*walker)(ao_ref *, tree, void *), void *data,
1720 bitmap *visited, unsigned int cnt)
1724 gimple def_stmt = SSA_NAME_DEF_STMT (vdef);
1727 && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef)))
1730 if (gimple_nop_p (def_stmt))
1732 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1736 *visited = BITMAP_ALLOC (NULL);
1737 for (i = 0; i < gimple_phi_num_args (def_stmt); ++i)
1738 cnt += walk_aliased_vdefs_1 (ref, gimple_phi_arg_def (def_stmt, i),
1739 walker, data, visited, 0);
1743 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1746 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1747 && (*walker) (ref, vdef, data))
1750 vdef = gimple_vuse (def_stmt);
1756 walk_aliased_vdefs (ao_ref *ref, tree vdef,
1757 bool (*walker)(ao_ref *, tree, void *), void *data,
1760 bitmap local_visited = NULL;
1763 timevar_push (TV_ALIAS_STMT_WALK);
1765 ret = walk_aliased_vdefs_1 (ref, vdef, walker, data,
1766 visited ? visited : &local_visited, 0);
1768 BITMAP_FREE (local_visited);
1770 timevar_pop (TV_ALIAS_STMT_WALK);