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 if (TREE_CODE (base1) == TARGET_MEM_REF)
675 if (TMR_SYMBOL (base1))
676 ptr1 = TMR_SYMBOL (base1);
677 else if (TMR_BASE (base1))
679 if (!POINTER_TYPE_P (TREE_TYPE (TMR_BASE (base1))))
681 ptr1 = TMR_BASE (base1);
687 ptr1 = TREE_OPERAND (base1, 0);
689 /* The offset embedded in MEM_REFs can be negative. Bias them
690 so that the resulting offset adjustment is positive. */
691 if (TREE_CODE (base1) == MEM_REF
692 || TREE_CODE (base1) == TARGET_MEM_REF)
694 double_int moff = mem_ref_offset (base1);
695 moff = double_int_lshift (moff,
697 ? 3 : exact_log2 (BITS_PER_UNIT),
698 HOST_BITS_PER_DOUBLE_INT, true);
699 if (double_int_negative_p (moff))
700 offset2p += double_int_neg (moff).low;
702 offset1p += moff.low;
705 /* If only one reference is based on a variable, they cannot alias if
706 the pointer access is beyond the extent of the variable access.
707 (the pointer base cannot validly point to an offset less than zero
709 They also cannot alias if the pointer may not point to the decl. */
710 if ((TREE_CODE (base1) != TARGET_MEM_REF || !TMR_INDEX (base1))
711 && !ranges_overlap_p (MAX (0, offset1p), -1, offset2p, max_size2))
713 if (!ptr_deref_may_alias_decl_p (ptr1, base2))
716 /* Disambiguations that rely on strict aliasing rules follow. */
717 if (!flag_strict_aliasing || !tbaa_p)
720 if (TREE_CODE (base1) == MEM_REF)
721 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
722 else if (TREE_CODE (base1) == TARGET_MEM_REF)
723 ptrtype1 = TREE_TYPE (TMR_OFFSET (base1));
725 ptrtype1 = TREE_TYPE (ptr1);
727 /* If the alias set for a pointer access is zero all bets are off. */
728 if (base1_alias_set == -1)
729 base1_alias_set = get_deref_alias_set (ptrtype1);
730 if (base1_alias_set == 0)
732 if (base2_alias_set == -1)
733 base2_alias_set = get_alias_set (base2);
735 /* If both references are through the same type, they do not alias
736 if the accesses do not overlap. This does extra disambiguation
737 for mixed/pointer accesses but requires strict aliasing.
738 For MEM_REFs we require that the component-ref offset we computed
739 is relative to the start of the type which we ensure by
740 comparing rvalue and access type and disregarding the constant
742 if ((TREE_CODE (base1) != TARGET_MEM_REF || !TMR_INDEX (base1))
743 && (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) != TARGET_MEM_REF
782 && (TREE_CODE (base1) != MEM_REF
783 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1))
784 return aliasing_component_refs_p (ref1, TREE_TYPE (ptrtype1),
785 ref1_alias_set, base1_alias_set,
787 ref2, TREE_TYPE (base2),
788 ref2_alias_set, base2_alias_set,
789 offset2, max_size2, true);
794 /* Return true if two indirect references based on *PTR1
795 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
796 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have
797 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
798 in which case they are computed on-demand. REF1 and REF2
799 if non-NULL are the complete memory reference trees. */
802 indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
803 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
804 alias_set_type ref1_alias_set,
805 alias_set_type base1_alias_set,
806 tree ref2 ATTRIBUTE_UNUSED, tree base2,
807 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
808 alias_set_type ref2_alias_set,
809 alias_set_type base2_alias_set, bool tbaa_p)
813 tree ptrtype1, ptrtype2;
815 if (TREE_CODE (base1) == TARGET_MEM_REF)
817 if (TMR_SYMBOL (base1))
818 ptr1 = TMR_SYMBOL (base1);
819 else if (TMR_BASE (base1))
821 if (!POINTER_TYPE_P (TREE_TYPE (TMR_BASE (base1))))
823 ptr1 = TMR_BASE (base1);
829 ptr1 = TREE_OPERAND (base1, 0);
831 if (TREE_CODE (base2) == TARGET_MEM_REF)
833 if (TMR_SYMBOL (base2))
834 ptr2 = TMR_SYMBOL (base2);
835 else if (TMR_BASE (base2))
837 if (!POINTER_TYPE_P (TREE_TYPE (TMR_BASE (base2))))
839 ptr2 = TMR_BASE (base2);
845 ptr2 = TREE_OPERAND (base2, 0);
847 /* If both bases are based on pointers they cannot alias if they may not
848 point to the same memory object or if they point to the same object
849 and the accesses do not overlap. */
850 if ((!cfun || gimple_in_ssa_p (cfun))
851 && operand_equal_p (ptr1, ptr2, 0)
852 && (((TREE_CODE (base1) != TARGET_MEM_REF
853 || !TMR_INDEX (base1))
854 && (TREE_CODE (base2) != TARGET_MEM_REF
855 || !TMR_INDEX (base2)))
856 || (TREE_CODE (base1) == TARGET_MEM_REF
857 && TREE_CODE (base2) == TARGET_MEM_REF
858 && (TMR_STEP (base1) == TMR_STEP (base2)
859 || (TMR_STEP (base1) && TMR_STEP (base2)
860 && operand_equal_p (TMR_STEP (base1),
861 TMR_STEP (base2), 0)))
862 && operand_equal_p (TMR_INDEX (base1), TMR_INDEX (base2), 0))))
864 /* The offset embedded in MEM_REFs can be negative. Bias them
865 so that the resulting offset adjustment is positive. */
866 if (TREE_CODE (base1) == MEM_REF
867 || TREE_CODE (base1) == TARGET_MEM_REF)
869 double_int moff = mem_ref_offset (base1);
870 moff = double_int_lshift (moff,
872 ? 3 : exact_log2 (BITS_PER_UNIT),
873 HOST_BITS_PER_DOUBLE_INT, true);
874 if (double_int_negative_p (moff))
875 offset2 += double_int_neg (moff).low;
879 if (TREE_CODE (base2) == MEM_REF
880 || TREE_CODE (base2) == TARGET_MEM_REF)
882 double_int moff = mem_ref_offset (base2);
883 moff = double_int_lshift (moff,
885 ? 3 : exact_log2 (BITS_PER_UNIT),
886 HOST_BITS_PER_DOUBLE_INT, true);
887 if (double_int_negative_p (moff))
888 offset1 += double_int_neg (moff).low;
892 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
894 if (!ptr_derefs_may_alias_p (ptr1, ptr2))
897 /* Disambiguations that rely on strict aliasing rules follow. */
898 if (!flag_strict_aliasing || !tbaa_p)
901 if (TREE_CODE (base1) == MEM_REF)
902 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
903 else if (TREE_CODE (base1) == TARGET_MEM_REF)
904 ptrtype1 = TREE_TYPE (TMR_OFFSET (base1));
906 ptrtype1 = TREE_TYPE (ptr1);
907 if (TREE_CODE (base2) == MEM_REF)
908 ptrtype2 = TREE_TYPE (TREE_OPERAND (base2, 1));
909 else if (TREE_CODE (base2) == TARGET_MEM_REF)
910 ptrtype2 = TREE_TYPE (TMR_OFFSET (base2));
912 ptrtype2 = TREE_TYPE (ptr2);
914 /* If the alias set for a pointer access is zero all bets are off. */
915 if (base1_alias_set == -1)
916 base1_alias_set = get_deref_alias_set (ptrtype1);
917 if (base1_alias_set == 0)
919 if (base2_alias_set == -1)
920 base2_alias_set = get_deref_alias_set (ptrtype2);
921 if (base2_alias_set == 0)
924 /* If both references are through the same type, they do not alias
925 if the accesses do not overlap. This does extra disambiguation
926 for mixed/pointer accesses but requires strict aliasing. */
927 if ((TREE_CODE (base1) != TARGET_MEM_REF || !TMR_INDEX (base1))
928 && (TREE_CODE (base2) != TARGET_MEM_REF || !TMR_INDEX (base2))
929 && (TREE_CODE (base1) != MEM_REF
930 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
931 && (TREE_CODE (base2) != MEM_REF
932 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1)
933 && same_type_for_tbaa (TREE_TYPE (ptrtype1),
934 TREE_TYPE (ptrtype2)) == 1)
935 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
937 /* Do type-based disambiguation. */
938 if (base1_alias_set != base2_alias_set
939 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
942 /* Do access-path based disambiguation. */
944 && handled_component_p (ref1)
945 && handled_component_p (ref2)
946 && TREE_CODE (base1) != TARGET_MEM_REF
947 && TREE_CODE (base2) != TARGET_MEM_REF
948 && (TREE_CODE (base1) != MEM_REF
949 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
950 && (TREE_CODE (base2) != MEM_REF
951 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1))
952 return aliasing_component_refs_p (ref1, TREE_TYPE (ptrtype1),
953 ref1_alias_set, base1_alias_set,
955 ref2, TREE_TYPE (ptrtype2),
956 ref2_alias_set, base2_alias_set,
957 offset2, max_size2, false);
962 /* Return true, if the two memory references REF1 and REF2 may alias. */
965 refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
968 HOST_WIDE_INT offset1 = 0, offset2 = 0;
969 HOST_WIDE_INT max_size1 = -1, max_size2 = -1;
970 bool var1_p, var2_p, ind1_p, ind2_p;
972 gcc_checking_assert ((!ref1->ref
973 || TREE_CODE (ref1->ref) == SSA_NAME
974 || DECL_P (ref1->ref)
975 || handled_component_p (ref1->ref)
976 || INDIRECT_REF_P (ref1->ref)
977 || TREE_CODE (ref1->ref) == MEM_REF
978 || TREE_CODE (ref1->ref) == TARGET_MEM_REF)
980 || TREE_CODE (ref2->ref) == SSA_NAME
981 || DECL_P (ref2->ref)
982 || handled_component_p (ref2->ref)
983 || INDIRECT_REF_P (ref2->ref)
984 || TREE_CODE (ref2->ref) == MEM_REF
985 || TREE_CODE (ref2->ref) == TARGET_MEM_REF));
987 /* Decompose the references into their base objects and the access. */
988 base1 = ao_ref_base (ref1);
989 offset1 = ref1->offset;
990 max_size1 = ref1->max_size;
991 base2 = ao_ref_base (ref2);
992 offset2 = ref2->offset;
993 max_size2 = ref2->max_size;
995 /* We can end up with registers or constants as bases for example from
996 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
997 which is seen as a struct copy. */
998 if (TREE_CODE (base1) == SSA_NAME
999 || TREE_CODE (base2) == SSA_NAME
1000 || TREE_CODE (base1) == CONST_DECL
1001 || TREE_CODE (base2) == CONST_DECL
1002 || is_gimple_min_invariant (base1)
1003 || is_gimple_min_invariant (base2))
1006 /* We can end up refering to code via function and label decls.
1007 As we likely do not properly track code aliases conservatively
1009 if (TREE_CODE (base1) == FUNCTION_DECL
1010 || TREE_CODE (base2) == FUNCTION_DECL
1011 || TREE_CODE (base1) == LABEL_DECL
1012 || TREE_CODE (base2) == LABEL_DECL)
1015 /* Defer to simple offset based disambiguation if we have
1016 references based on two decls. Do this before defering to
1017 TBAA to handle must-alias cases in conformance with the
1018 GCC extension of allowing type-punning through unions. */
1019 var1_p = SSA_VAR_P (base1);
1020 var2_p = SSA_VAR_P (base2);
1021 if (var1_p && var2_p)
1022 return decl_refs_may_alias_p (base1, offset1, max_size1,
1023 base2, offset2, max_size2);
1025 ind1_p = (INDIRECT_REF_P (base1)
1026 || (TREE_CODE (base1) == MEM_REF)
1027 || (TREE_CODE (base1) == TARGET_MEM_REF));
1028 ind2_p = (INDIRECT_REF_P (base2)
1029 || (TREE_CODE (base2) == MEM_REF)
1030 || (TREE_CODE (base2) == TARGET_MEM_REF));
1032 /* Canonicalize the pointer-vs-decl case. */
1033 if (ind1_p && var2_p)
1038 tmp1 = offset1; offset1 = offset2; offset2 = tmp1;
1039 tmp1 = max_size1; max_size1 = max_size2; max_size2 = tmp1;
1040 tmp2 = base1; base1 = base2; base2 = tmp2;
1041 tmp3 = ref1; ref1 = ref2; ref2 = tmp3;
1048 /* First defer to TBAA if possible. */
1050 && flag_strict_aliasing
1051 && !alias_sets_conflict_p (ao_ref_alias_set (ref1),
1052 ao_ref_alias_set (ref2)))
1055 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */
1056 if (var1_p && ind2_p)
1057 return indirect_ref_may_alias_decl_p (ref2->ref, base2,
1059 ao_ref_alias_set (ref2), -1,
1062 ao_ref_alias_set (ref1),
1063 ao_ref_base_alias_set (ref1),
1065 else if (ind1_p && ind2_p)
1066 return indirect_refs_may_alias_p (ref1->ref, base1,
1068 ao_ref_alias_set (ref1), -1,
1071 ao_ref_alias_set (ref2), -1,
1078 refs_may_alias_p (tree ref1, tree ref2)
1082 ao_ref_init (&r1, ref1);
1083 ao_ref_init (&r2, ref2);
1084 res = refs_may_alias_p_1 (&r1, &r2, true);
1086 ++alias_stats.refs_may_alias_p_may_alias;
1088 ++alias_stats.refs_may_alias_p_no_alias;
1092 /* Returns true if there is a anti-dependence for the STORE that
1093 executes after the LOAD. */
1096 refs_anti_dependent_p (tree load, tree store)
1099 ao_ref_init (&r1, load);
1100 ao_ref_init (&r2, store);
1101 return refs_may_alias_p_1 (&r1, &r2, false);
1104 /* Returns true if there is a output dependence for the stores
1105 STORE1 and STORE2. */
1108 refs_output_dependent_p (tree store1, tree store2)
1111 ao_ref_init (&r1, store1);
1112 ao_ref_init (&r2, store2);
1113 return refs_may_alias_p_1 (&r1, &r2, false);
1116 /* If the call CALL may use the memory reference REF return true,
1117 otherwise return false. */
1120 ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
1124 int flags = gimple_call_flags (call);
1126 /* Const functions without a static chain do not implicitly use memory. */
1127 if (!gimple_call_chain (call)
1128 && (flags & (ECF_CONST|ECF_NOVOPS)))
1131 base = ao_ref_base (ref);
1135 /* If the reference is based on a decl that is not aliased the call
1136 cannot possibly use it. */
1138 && !may_be_aliased (base)
1139 /* But local statics can be used through recursion. */
1140 && !is_global_var (base))
1143 callee = gimple_call_fndecl (call);
1145 /* Handle those builtin functions explicitly that do not act as
1146 escape points. See tree-ssa-structalias.c:find_func_aliases
1147 for the list of builtins we might need to handle here. */
1148 if (callee != NULL_TREE
1149 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1150 switch (DECL_FUNCTION_CODE (callee))
1152 /* All the following functions clobber memory pointed to by
1153 their first argument. */
1154 case BUILT_IN_STRCPY:
1155 case BUILT_IN_STRNCPY:
1156 case BUILT_IN_MEMCPY:
1157 case BUILT_IN_MEMMOVE:
1158 case BUILT_IN_MEMPCPY:
1159 case BUILT_IN_STPCPY:
1160 case BUILT_IN_STPNCPY:
1161 case BUILT_IN_STRCAT:
1162 case BUILT_IN_STRNCAT:
1165 tree size = NULL_TREE;
1166 if (gimple_call_num_args (call) == 3)
1167 size = gimple_call_arg (call, 2);
1168 ao_ref_init_from_ptr_and_size (&dref,
1169 gimple_call_arg (call, 1),
1171 return refs_may_alias_p_1 (&dref, ref, false);
1173 case BUILT_IN_BCOPY:
1176 tree size = gimple_call_arg (call, 2);
1177 ao_ref_init_from_ptr_and_size (&dref,
1178 gimple_call_arg (call, 0),
1180 return refs_may_alias_p_1 (&dref, ref, false);
1182 /* The following builtins do not read from memory. */
1184 case BUILT_IN_MALLOC:
1185 case BUILT_IN_CALLOC:
1186 case BUILT_IN_MEMSET:
1187 case BUILT_IN_FREXP:
1188 case BUILT_IN_FREXPF:
1189 case BUILT_IN_FREXPL:
1190 case BUILT_IN_GAMMA_R:
1191 case BUILT_IN_GAMMAF_R:
1192 case BUILT_IN_GAMMAL_R:
1193 case BUILT_IN_LGAMMA_R:
1194 case BUILT_IN_LGAMMAF_R:
1195 case BUILT_IN_LGAMMAL_R:
1197 case BUILT_IN_MODFF:
1198 case BUILT_IN_MODFL:
1199 case BUILT_IN_REMQUO:
1200 case BUILT_IN_REMQUOF:
1201 case BUILT_IN_REMQUOL:
1202 case BUILT_IN_SINCOS:
1203 case BUILT_IN_SINCOSF:
1204 case BUILT_IN_SINCOSL:
1208 /* Fallthru to general call handling. */;
1211 /* Check if base is a global static variable that is not read
1213 if (TREE_CODE (base) == VAR_DECL
1214 && TREE_STATIC (base))
1218 if (callee != NULL_TREE
1220 = ipa_reference_get_not_read_global (cgraph_node (callee)))
1221 && bitmap_bit_p (not_read, DECL_UID (base)))
1225 /* Check if the base variable is call-used. */
1228 if (pt_solution_includes (gimple_call_use_set (call), base))
1231 else if ((INDIRECT_REF_P (base)
1232 || TREE_CODE (base) == MEM_REF)
1233 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1235 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1239 if (pt_solutions_intersect (gimple_call_use_set (call), &pi->pt))
1245 /* Inspect call arguments for passed-by-value aliases. */
1247 for (i = 0; i < gimple_call_num_args (call); ++i)
1249 tree op = gimple_call_arg (call, i);
1250 int flags = gimple_call_arg_flags (call, i);
1252 if (flags & EAF_UNUSED)
1255 if (TREE_CODE (op) == WITH_SIZE_EXPR)
1256 op = TREE_OPERAND (op, 0);
1258 if (TREE_CODE (op) != SSA_NAME
1259 && !is_gimple_min_invariant (op))
1262 ao_ref_init (&r, op);
1263 if (refs_may_alias_p_1 (&r, ref, true))
1272 ref_maybe_used_by_call_p (gimple call, tree ref)
1276 ao_ref_init (&r, ref);
1277 res = ref_maybe_used_by_call_p_1 (call, &r);
1279 ++alias_stats.ref_maybe_used_by_call_p_may_alias;
1281 ++alias_stats.ref_maybe_used_by_call_p_no_alias;
1286 /* If the statement STMT may use the memory reference REF return
1287 true, otherwise return false. */
1290 ref_maybe_used_by_stmt_p (gimple stmt, tree ref)
1292 if (is_gimple_assign (stmt))
1296 /* All memory assign statements are single. */
1297 if (!gimple_assign_single_p (stmt))
1300 rhs = gimple_assign_rhs1 (stmt);
1301 if (is_gimple_reg (rhs)
1302 || is_gimple_min_invariant (rhs)
1303 || gimple_assign_rhs_code (stmt) == CONSTRUCTOR)
1306 return refs_may_alias_p (rhs, ref);
1308 else if (is_gimple_call (stmt))
1309 return ref_maybe_used_by_call_p (stmt, ref);
1314 /* If the call in statement CALL may clobber the memory reference REF
1315 return true, otherwise return false. */
1318 call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
1323 /* If the call is pure or const it cannot clobber anything. */
1324 if (gimple_call_flags (call)
1325 & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS))
1328 base = ao_ref_base (ref);
1332 if (TREE_CODE (base) == SSA_NAME
1333 || CONSTANT_CLASS_P (base))
1336 /* If the reference is based on a decl that is not aliased the call
1337 cannot possibly clobber it. */
1339 && !may_be_aliased (base)
1340 /* But local non-readonly statics can be modified through recursion
1341 or the call may implement a threading barrier which we must
1342 treat as may-def. */
1343 && (TREE_READONLY (base)
1344 || !is_global_var (base)))
1347 callee = gimple_call_fndecl (call);
1349 /* Handle those builtin functions explicitly that do not act as
1350 escape points. See tree-ssa-structalias.c:find_func_aliases
1351 for the list of builtins we might need to handle here. */
1352 if (callee != NULL_TREE
1353 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1354 switch (DECL_FUNCTION_CODE (callee))
1356 /* All the following functions clobber memory pointed to by
1357 their first argument. */
1358 case BUILT_IN_STRCPY:
1359 case BUILT_IN_STRNCPY:
1360 case BUILT_IN_MEMCPY:
1361 case BUILT_IN_MEMMOVE:
1362 case BUILT_IN_MEMPCPY:
1363 case BUILT_IN_STPCPY:
1364 case BUILT_IN_STPNCPY:
1365 case BUILT_IN_STRCAT:
1366 case BUILT_IN_STRNCAT:
1367 case BUILT_IN_MEMSET:
1370 tree size = NULL_TREE;
1371 if (gimple_call_num_args (call) == 3)
1372 size = gimple_call_arg (call, 2);
1373 ao_ref_init_from_ptr_and_size (&dref,
1374 gimple_call_arg (call, 0),
1376 return refs_may_alias_p_1 (&dref, ref, false);
1378 case BUILT_IN_BCOPY:
1381 tree size = gimple_call_arg (call, 2);
1382 ao_ref_init_from_ptr_and_size (&dref,
1383 gimple_call_arg (call, 1),
1385 return refs_may_alias_p_1 (&dref, ref, false);
1387 /* Allocating memory does not have any side-effects apart from
1388 being the definition point for the pointer. */
1389 case BUILT_IN_MALLOC:
1390 case BUILT_IN_CALLOC:
1391 /* Unix98 specifies that errno is set on allocation failure.
1392 Until we properly can track the errno location assume it
1393 is not a local decl but external or anonymous storage in
1394 a different translation unit. Also assume it is of
1395 type int as required by the standard. */
1397 && TREE_TYPE (base) == integer_type_node)
1399 struct ptr_info_def *pi;
1401 && !TREE_STATIC (base))
1403 else if ((INDIRECT_REF_P (base)
1404 || TREE_CODE (base) == MEM_REF)
1405 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME
1406 && (pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0))))
1407 return pi->pt.anything || pi->pt.nonlocal;
1410 /* Freeing memory kills the pointed-to memory. More importantly
1411 the call has to serve as a barrier for moving loads and stores
1415 tree ptr = gimple_call_arg (call, 0);
1416 return ptr_deref_may_alias_ref_p_1 (ptr, ref);
1418 case BUILT_IN_GAMMA_R:
1419 case BUILT_IN_GAMMAF_R:
1420 case BUILT_IN_GAMMAL_R:
1421 case BUILT_IN_LGAMMA_R:
1422 case BUILT_IN_LGAMMAF_R:
1423 case BUILT_IN_LGAMMAL_R:
1425 tree out = gimple_call_arg (call, 1);
1426 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1428 if (flag_errno_math)
1432 case BUILT_IN_FREXP:
1433 case BUILT_IN_FREXPF:
1434 case BUILT_IN_FREXPL:
1436 case BUILT_IN_MODFF:
1437 case BUILT_IN_MODFL:
1439 tree out = gimple_call_arg (call, 1);
1440 return ptr_deref_may_alias_ref_p_1 (out, ref);
1442 case BUILT_IN_REMQUO:
1443 case BUILT_IN_REMQUOF:
1444 case BUILT_IN_REMQUOL:
1446 tree out = gimple_call_arg (call, 2);
1447 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1449 if (flag_errno_math)
1453 case BUILT_IN_SINCOS:
1454 case BUILT_IN_SINCOSF:
1455 case BUILT_IN_SINCOSL:
1457 tree sin = gimple_call_arg (call, 1);
1458 tree cos = gimple_call_arg (call, 2);
1459 return (ptr_deref_may_alias_ref_p_1 (sin, ref)
1460 || ptr_deref_may_alias_ref_p_1 (cos, ref));
1463 /* Fallthru to general call handling. */;
1466 /* Check if base is a global static variable that is not written
1468 if (callee != NULL_TREE
1469 && TREE_CODE (base) == VAR_DECL
1470 && TREE_STATIC (base))
1475 = ipa_reference_get_not_written_global (cgraph_node (callee)))
1476 && bitmap_bit_p (not_written, DECL_UID (base)))
1480 /* Check if the base variable is call-clobbered. */
1482 return pt_solution_includes (gimple_call_clobber_set (call), base);
1483 else if ((INDIRECT_REF_P (base)
1484 || TREE_CODE (base) == MEM_REF)
1485 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1487 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1491 return pt_solutions_intersect (gimple_call_clobber_set (call), &pi->pt);
1497 /* If the call in statement CALL may clobber the memory reference REF
1498 return true, otherwise return false. */
1501 call_may_clobber_ref_p (gimple call, tree ref)
1505 ao_ref_init (&r, ref);
1506 res = call_may_clobber_ref_p_1 (call, &r);
1508 ++alias_stats.call_may_clobber_ref_p_may_alias;
1510 ++alias_stats.call_may_clobber_ref_p_no_alias;
1515 /* If the statement STMT may clobber the memory reference REF return true,
1516 otherwise return false. */
1519 stmt_may_clobber_ref_p_1 (gimple stmt, ao_ref *ref)
1521 if (is_gimple_call (stmt))
1523 tree lhs = gimple_call_lhs (stmt);
1525 && !is_gimple_reg (lhs))
1528 ao_ref_init (&r, lhs);
1529 if (refs_may_alias_p_1 (ref, &r, true))
1533 return call_may_clobber_ref_p_1 (stmt, ref);
1535 else if (gimple_assign_single_p (stmt))
1537 tree lhs = gimple_assign_lhs (stmt);
1538 if (!is_gimple_reg (lhs))
1541 ao_ref_init (&r, gimple_assign_lhs (stmt));
1542 return refs_may_alias_p_1 (ref, &r, true);
1545 else if (gimple_code (stmt) == GIMPLE_ASM)
1552 stmt_may_clobber_ref_p (gimple stmt, tree ref)
1555 ao_ref_init (&r, ref);
1556 return stmt_may_clobber_ref_p_1 (stmt, &r);
1560 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand
1561 TARGET or a statement clobbering the memory reference REF in which
1562 case false is returned. The walk starts with VUSE, one argument of PHI. */
1565 maybe_skip_until (gimple phi, tree target, ao_ref *ref,
1566 tree vuse, bitmap *visited)
1569 *visited = BITMAP_ALLOC (NULL);
1571 bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi)));
1573 /* Walk until we hit the target. */
1574 while (vuse != target)
1576 gimple def_stmt = SSA_NAME_DEF_STMT (vuse);
1577 /* Recurse for PHI nodes. */
1578 if (gimple_code (def_stmt) == GIMPLE_PHI)
1580 /* An already visited PHI node ends the walk successfully. */
1581 if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt))))
1583 vuse = get_continuation_for_phi (def_stmt, ref, visited);
1588 /* A clobbering statement or the end of the IL ends it failing. */
1589 else if (gimple_nop_p (def_stmt)
1590 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1592 vuse = gimple_vuse (def_stmt);
1597 /* Starting from a PHI node for the virtual operand of the memory reference
1598 REF find a continuation virtual operand that allows to continue walking
1599 statements dominating PHI skipping only statements that cannot possibly
1600 clobber REF. Returns NULL_TREE if no suitable virtual operand can
1604 get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited)
1606 unsigned nargs = gimple_phi_num_args (phi);
1608 /* Through a single-argument PHI we can simply look through. */
1610 return PHI_ARG_DEF (phi, 0);
1612 /* For two arguments try to skip non-aliasing code until we hit
1613 the phi argument definition that dominates the other one. */
1616 tree arg0 = PHI_ARG_DEF (phi, 0);
1617 tree arg1 = PHI_ARG_DEF (phi, 1);
1618 gimple def0 = SSA_NAME_DEF_STMT (arg0);
1619 gimple def1 = SSA_NAME_DEF_STMT (arg1);
1624 else if (gimple_nop_p (def0)
1625 || (!gimple_nop_p (def1)
1626 && dominated_by_p (CDI_DOMINATORS,
1627 gimple_bb (def1), gimple_bb (def0))))
1629 if (maybe_skip_until (phi, arg0, ref, arg1, visited))
1632 else if (gimple_nop_p (def1)
1633 || dominated_by_p (CDI_DOMINATORS,
1634 gimple_bb (def0), gimple_bb (def1)))
1636 if (maybe_skip_until (phi, arg1, ref, arg0, visited))
1639 /* Special case of a diamond:
1641 goto (cond) ? L1 : L2
1642 L1: store1 = ... #MEM_2 = vuse(MEM_1)
1644 L2: store2 = ... #MEM_3 = vuse(MEM_1)
1645 L3: MEM_4 = PHI<MEM_2, MEM_3>
1646 We were called with the PHI at L3, MEM_2 and MEM_3 don't
1647 dominate each other, but still we can easily skip this PHI node
1648 if we recognize that the vuse MEM operand is the same for both,
1649 and that we can skip both statements (they don't clobber us).
1650 This is still linear. Don't use maybe_skip_until, that might
1651 potentially be slow. */
1652 else if ((common_vuse = gimple_vuse (def0))
1653 && common_vuse == gimple_vuse (def1))
1655 if (!stmt_may_clobber_ref_p_1 (def0, ref)
1656 && !stmt_may_clobber_ref_p_1 (def1, ref))
1664 /* Based on the memory reference REF and its virtual use VUSE call
1665 WALKER for each virtual use that is equivalent to VUSE, including VUSE
1666 itself. That is, for each virtual use for which its defining statement
1667 does not clobber REF.
1669 WALKER is called with REF, the current virtual use and DATA. If
1670 WALKER returns non-NULL the walk stops and its result is returned.
1671 At the end of a non-successful walk NULL is returned.
1673 TRANSLATE if non-NULL is called with a pointer to REF, the virtual
1674 use which definition is a statement that may clobber REF and DATA.
1675 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
1676 If TRANSLATE returns non-NULL the walk stops and its result is returned.
1677 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
1678 to adjust REF and *DATA to make that valid.
1680 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
1683 walk_non_aliased_vuses (ao_ref *ref, tree vuse,
1684 void *(*walker)(ao_ref *, tree, void *),
1685 void *(*translate)(ao_ref *, tree, void *), void *data)
1687 bitmap visited = NULL;
1690 timevar_push (TV_ALIAS_STMT_WALK);
1696 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1697 res = (*walker) (ref, vuse, data);
1701 def_stmt = SSA_NAME_DEF_STMT (vuse);
1702 if (gimple_nop_p (def_stmt))
1704 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1705 vuse = get_continuation_for_phi (def_stmt, ref, &visited);
1708 if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
1712 res = (*translate) (ref, vuse, data);
1713 /* Failed lookup and translation. */
1714 if (res == (void *)-1)
1719 /* Lookup succeeded. */
1720 else if (res != NULL)
1722 /* Translation succeeded, continue walking. */
1724 vuse = gimple_vuse (def_stmt);
1730 BITMAP_FREE (visited);
1732 timevar_pop (TV_ALIAS_STMT_WALK);
1738 /* Based on the memory reference REF call WALKER for each vdef which
1739 defining statement may clobber REF, starting with VDEF. If REF
1740 is NULL_TREE, each defining statement is visited.
1742 WALKER is called with REF, the current vdef and DATA. If WALKER
1743 returns true the walk is stopped, otherwise it continues.
1745 At PHI nodes walk_aliased_vdefs forks into one walk for reach
1746 PHI argument (but only one walk continues on merge points), the
1747 return value is true if any of the walks was successful.
1749 The function returns the number of statements walked. */
1752 walk_aliased_vdefs_1 (ao_ref *ref, tree vdef,
1753 bool (*walker)(ao_ref *, tree, void *), void *data,
1754 bitmap *visited, unsigned int cnt)
1758 gimple def_stmt = SSA_NAME_DEF_STMT (vdef);
1761 && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef)))
1764 if (gimple_nop_p (def_stmt))
1766 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1770 *visited = BITMAP_ALLOC (NULL);
1771 for (i = 0; i < gimple_phi_num_args (def_stmt); ++i)
1772 cnt += walk_aliased_vdefs_1 (ref, gimple_phi_arg_def (def_stmt, i),
1773 walker, data, visited, 0);
1777 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1780 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1781 && (*walker) (ref, vdef, data))
1784 vdef = gimple_vuse (def_stmt);
1790 walk_aliased_vdefs (ao_ref *ref, tree vdef,
1791 bool (*walker)(ao_ref *, tree, void *), void *data,
1794 bitmap local_visited = NULL;
1797 timevar_push (TV_ALIAS_STMT_WALK);
1799 ret = walk_aliased_vdefs_1 (ref, vdef, walker, data,
1800 visited ? visited : &local_visited, 0);
1802 BITMAP_FREE (local_visited);
1804 timevar_pop (TV_ALIAS_STMT_WALK);