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"
29 #include "basic-block.h"
32 #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"
46 #include "pointer-set.h"
47 #include "alloc-pool.h"
48 #include "tree-ssa-alias.h"
50 /* Broad overview of how alias analysis on gimple works:
52 Statements clobbering or using memory are linked through the
53 virtual operand factored use-def chain. The virtual operand
54 is unique per function, its symbol is accessible via gimple_vop (cfun).
55 Virtual operands are used for efficiently walking memory statements
56 in the gimple IL and are useful for things like value-numbering as
57 a generation count for memory references.
59 SSA_NAME pointers may have associated points-to information
60 accessible via the SSA_NAME_PTR_INFO macro. Flow-insensitive
61 points-to information is (re-)computed by the TODO_rebuild_alias
62 pass manager todo. Points-to information is also used for more
63 precise tracking of call-clobbered and call-used variables and
64 related disambiguations.
66 This file contains functions for disambiguating memory references,
67 the so called alias-oracle and tools for walking of the gimple IL.
69 The main alias-oracle entry-points are
71 bool stmt_may_clobber_ref_p (gimple, tree)
73 This function queries if a statement may invalidate (parts of)
74 the memory designated by the reference tree argument.
76 bool ref_maybe_used_by_stmt_p (gimple, tree)
78 This function queries if a statement may need (parts of) the
79 memory designated by the reference tree argument.
81 There are variants of these functions that only handle the call
82 part of a statement, call_may_clobber_ref_p and ref_maybe_used_by_call_p.
83 Note that these do not disambiguate against a possible call lhs.
85 bool refs_may_alias_p (tree, tree)
87 This function tries to disambiguate two reference trees.
89 bool ptr_deref_may_alias_global_p (tree)
91 This function queries if dereferencing a pointer variable may
94 More low-level disambiguators are available and documented in
95 this file. Low-level disambiguators dealing with points-to
96 information are in tree-ssa-structalias.c. */
99 /* Query statistics for the different low-level disambiguators.
100 A high-level query may trigger multiple of them. */
103 unsigned HOST_WIDE_INT refs_may_alias_p_may_alias;
104 unsigned HOST_WIDE_INT refs_may_alias_p_no_alias;
105 unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_may_alias;
106 unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_no_alias;
107 unsigned HOST_WIDE_INT call_may_clobber_ref_p_may_alias;
108 unsigned HOST_WIDE_INT call_may_clobber_ref_p_no_alias;
112 dump_alias_stats (FILE *s)
114 fprintf (s, "\nAlias oracle query stats:\n");
115 fprintf (s, " refs_may_alias_p: "
116 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
117 HOST_WIDE_INT_PRINT_DEC" queries\n",
118 alias_stats.refs_may_alias_p_no_alias,
119 alias_stats.refs_may_alias_p_no_alias
120 + alias_stats.refs_may_alias_p_may_alias);
121 fprintf (s, " ref_maybe_used_by_call_p: "
122 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
123 HOST_WIDE_INT_PRINT_DEC" queries\n",
124 alias_stats.ref_maybe_used_by_call_p_no_alias,
125 alias_stats.refs_may_alias_p_no_alias
126 + alias_stats.ref_maybe_used_by_call_p_may_alias);
127 fprintf (s, " call_may_clobber_ref_p: "
128 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
129 HOST_WIDE_INT_PRINT_DEC" queries\n",
130 alias_stats.call_may_clobber_ref_p_no_alias,
131 alias_stats.call_may_clobber_ref_p_no_alias
132 + alias_stats.call_may_clobber_ref_p_may_alias);
136 /* Return true, if dereferencing PTR may alias with a global variable. */
139 ptr_deref_may_alias_global_p (tree ptr)
141 struct ptr_info_def *pi;
143 /* If we end up with a pointer constant here that may point
145 if (TREE_CODE (ptr) != SSA_NAME)
148 pi = SSA_NAME_PTR_INFO (ptr);
150 /* If we do not have points-to information for this variable,
155 /* ??? This does not use TBAA to prune globals ptr may not access. */
156 return pt_solution_includes_global (&pi->pt);
159 /* Return true if dereferencing PTR may alias DECL.
160 The caller is responsible for applying TBAA to see if PTR
161 may access DECL at all. */
164 ptr_deref_may_alias_decl_p (tree ptr, tree decl)
166 struct ptr_info_def *pi;
168 /* Conversions are irrelevant for points-to information and
169 data-dependence analysis can feed us those. */
172 /* Anything we do not explicilty handle aliases. */
173 if ((TREE_CODE (ptr) != SSA_NAME
174 && TREE_CODE (ptr) != ADDR_EXPR
175 && TREE_CODE (ptr) != POINTER_PLUS_EXPR)
176 || !POINTER_TYPE_P (TREE_TYPE (ptr))
177 || (TREE_CODE (decl) != VAR_DECL
178 && TREE_CODE (decl) != PARM_DECL
179 && TREE_CODE (decl) != RESULT_DECL))
182 /* Disregard pointer offsetting. */
183 if (TREE_CODE (ptr) == POINTER_PLUS_EXPR)
187 ptr = TREE_OPERAND (ptr, 0);
189 while (TREE_CODE (ptr) == POINTER_PLUS_EXPR);
190 return ptr_deref_may_alias_decl_p (ptr, decl);
193 /* ADDR_EXPR pointers either just offset another pointer or directly
194 specify the pointed-to set. */
195 if (TREE_CODE (ptr) == ADDR_EXPR)
197 tree base = get_base_address (TREE_OPERAND (ptr, 0));
199 && (INDIRECT_REF_P (base)
200 || TREE_CODE (base) == MEM_REF))
201 ptr = TREE_OPERAND (base, 0);
206 && CONSTANT_CLASS_P (base))
212 /* Non-aliased variables can not be pointed to. */
213 if (!may_be_aliased (decl))
216 /* If we do not have useful points-to information for this pointer
217 we cannot disambiguate anything else. */
218 pi = SSA_NAME_PTR_INFO (ptr);
222 /* If the decl can be used as a restrict tag and we have a restrict
223 pointer and that pointers points-to set doesn't contain this decl
224 then they can't alias. */
225 if (DECL_RESTRICTED_P (decl)
226 && TYPE_RESTRICT (TREE_TYPE (ptr))
227 && pi->pt.vars_contains_restrict)
228 return bitmap_bit_p (pi->pt.vars, DECL_PT_UID (decl));
230 return pt_solution_includes (&pi->pt, decl);
233 /* Return true if dereferenced PTR1 and PTR2 may alias.
234 The caller is responsible for applying TBAA to see if accesses
235 through PTR1 and PTR2 may conflict at all. */
238 ptr_derefs_may_alias_p (tree ptr1, tree ptr2)
240 struct ptr_info_def *pi1, *pi2;
242 /* Conversions are irrelevant for points-to information and
243 data-dependence analysis can feed us those. */
247 /* Anything we do not explicilty handle aliases. */
248 if ((TREE_CODE (ptr1) != SSA_NAME
249 && TREE_CODE (ptr1) != ADDR_EXPR
250 && TREE_CODE (ptr1) != POINTER_PLUS_EXPR)
251 || (TREE_CODE (ptr2) != SSA_NAME
252 && TREE_CODE (ptr2) != ADDR_EXPR
253 && TREE_CODE (ptr2) != POINTER_PLUS_EXPR)
254 || !POINTER_TYPE_P (TREE_TYPE (ptr1))
255 || !POINTER_TYPE_P (TREE_TYPE (ptr2)))
258 /* Disregard pointer offsetting. */
259 if (TREE_CODE (ptr1) == POINTER_PLUS_EXPR)
263 ptr1 = TREE_OPERAND (ptr1, 0);
265 while (TREE_CODE (ptr1) == POINTER_PLUS_EXPR);
266 return ptr_derefs_may_alias_p (ptr1, ptr2);
268 if (TREE_CODE (ptr2) == POINTER_PLUS_EXPR)
272 ptr2 = TREE_OPERAND (ptr2, 0);
274 while (TREE_CODE (ptr2) == POINTER_PLUS_EXPR);
275 return ptr_derefs_may_alias_p (ptr1, ptr2);
278 /* ADDR_EXPR pointers either just offset another pointer or directly
279 specify the pointed-to set. */
280 if (TREE_CODE (ptr1) == ADDR_EXPR)
282 tree base = get_base_address (TREE_OPERAND (ptr1, 0));
284 && (INDIRECT_REF_P (base)
285 || TREE_CODE (base) == MEM_REF))
286 ptr1 = TREE_OPERAND (base, 0);
289 return ptr_deref_may_alias_decl_p (ptr2, base);
293 if (TREE_CODE (ptr2) == ADDR_EXPR)
295 tree base = get_base_address (TREE_OPERAND (ptr2, 0));
297 && (INDIRECT_REF_P (base)
298 || TREE_CODE (base) == MEM_REF))
299 ptr2 = TREE_OPERAND (base, 0);
302 return ptr_deref_may_alias_decl_p (ptr1, base);
307 /* We may end up with two empty points-to solutions for two same pointers.
308 In this case we still want to say both pointers alias, so shortcut
313 /* If we do not have useful points-to information for either pointer
314 we cannot disambiguate anything else. */
315 pi1 = SSA_NAME_PTR_INFO (ptr1);
316 pi2 = SSA_NAME_PTR_INFO (ptr2);
320 /* If both pointers are restrict-qualified try to disambiguate
321 with restrict information. */
322 if (TYPE_RESTRICT (TREE_TYPE (ptr1))
323 && TYPE_RESTRICT (TREE_TYPE (ptr2))
324 && !pt_solutions_same_restrict_base (&pi1->pt, &pi2->pt))
327 /* ??? This does not use TBAA to prune decls from the intersection
328 that not both pointers may access. */
329 return pt_solutions_intersect (&pi1->pt, &pi2->pt);
332 /* Return true if dereferencing PTR may alias *REF.
333 The caller is responsible for applying TBAA to see if PTR
334 may access *REF at all. */
337 ptr_deref_may_alias_ref_p_1 (tree ptr, ao_ref *ref)
339 tree base = ao_ref_base (ref);
341 if (INDIRECT_REF_P (base)
342 || TREE_CODE (base) == MEM_REF)
343 return ptr_derefs_may_alias_p (ptr, TREE_OPERAND (base, 0));
344 else if (SSA_VAR_P (base))
345 return ptr_deref_may_alias_decl_p (ptr, base);
351 /* Dump alias information on FILE. */
354 dump_alias_info (FILE *file)
358 = lang_hooks.decl_printable_name (current_function_decl, 2);
359 referenced_var_iterator rvi;
362 fprintf (file, "\n\nAlias information for %s\n\n", funcname);
364 fprintf (file, "Aliased symbols\n\n");
366 FOR_EACH_REFERENCED_VAR (cfun, var, rvi)
368 if (may_be_aliased (var))
369 dump_variable (file, var);
372 fprintf (file, "\nCall clobber information\n");
374 fprintf (file, "\nESCAPED");
375 dump_points_to_solution (file, &cfun->gimple_df->escaped);
377 fprintf (file, "\n\nFlow-insensitive points-to information\n\n");
379 for (i = 1; i < num_ssa_names; i++)
381 tree ptr = ssa_name (i);
382 struct ptr_info_def *pi;
385 || SSA_NAME_IN_FREE_LIST (ptr))
388 pi = SSA_NAME_PTR_INFO (ptr);
390 dump_points_to_info_for (file, ptr);
393 fprintf (file, "\n");
397 /* Dump alias information on stderr. */
400 debug_alias_info (void)
402 dump_alias_info (stderr);
406 /* Dump the points-to set *PT into FILE. */
409 dump_points_to_solution (FILE *file, struct pt_solution *pt)
412 fprintf (file, ", points-to anything");
415 fprintf (file, ", points-to non-local");
418 fprintf (file, ", points-to escaped");
421 fprintf (file, ", points-to unit escaped");
424 fprintf (file, ", points-to NULL");
428 fprintf (file, ", points-to vars: ");
429 dump_decl_set (file, pt->vars);
430 if (pt->vars_contains_global)
431 fprintf (file, " (includes global vars)");
432 if (pt->vars_contains_restrict)
433 fprintf (file, " (includes restrict tags)");
437 /* Dump points-to information for SSA_NAME PTR into FILE. */
440 dump_points_to_info_for (FILE *file, tree ptr)
442 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
444 print_generic_expr (file, ptr, dump_flags);
447 dump_points_to_solution (file, &pi->pt);
449 fprintf (file, ", points-to anything");
451 fprintf (file, "\n");
455 /* Dump points-to information for VAR into stderr. */
458 debug_points_to_info_for (tree var)
460 dump_points_to_info_for (stderr, var);
464 /* Initializes the alias-oracle reference representation *R from REF. */
467 ao_ref_init (ao_ref *r, tree ref)
474 r->ref_alias_set = -1;
475 r->base_alias_set = -1;
478 /* Returns the base object of the memory reference *REF. */
481 ao_ref_base (ao_ref *ref)
485 ref->base = get_ref_base_and_extent (ref->ref, &ref->offset, &ref->size,
490 /* Returns the base object alias set of the memory reference *REF. */
492 static alias_set_type
493 ao_ref_base_alias_set (ao_ref *ref)
496 if (ref->base_alias_set != -1)
497 return ref->base_alias_set;
501 while (handled_component_p (base_ref))
502 base_ref = TREE_OPERAND (base_ref, 0);
503 ref->base_alias_set = get_alias_set (base_ref);
504 return ref->base_alias_set;
507 /* Returns the reference alias set of the memory reference *REF. */
510 ao_ref_alias_set (ao_ref *ref)
512 if (ref->ref_alias_set != -1)
513 return ref->ref_alias_set;
514 ref->ref_alias_set = get_alias_set (ref->ref);
515 return ref->ref_alias_set;
518 /* Init an alias-oracle reference representation from a gimple pointer
519 PTR and a gimple size SIZE in bytes. If SIZE is NULL_TREE the the
520 size is assumed to be unknown. The access is assumed to be only
521 to or after of the pointer target, not before it. */
524 ao_ref_init_from_ptr_and_size (ao_ref *ref, tree ptr, tree size)
526 HOST_WIDE_INT t1, t2;
527 ref->ref = NULL_TREE;
528 if (TREE_CODE (ptr) == ADDR_EXPR)
529 ref->base = get_ref_base_and_extent (TREE_OPERAND (ptr, 0),
530 &ref->offset, &t1, &t2);
533 ref->base = build2 (MEM_REF, char_type_node,
534 ptr, null_pointer_node);
538 && host_integerp (size, 0)
539 && TREE_INT_CST_LOW (size) * 8 / 8 == TREE_INT_CST_LOW (size))
540 ref->max_size = ref->size = TREE_INT_CST_LOW (size) * 8;
542 ref->max_size = ref->size = -1;
543 ref->ref_alias_set = 0;
544 ref->base_alias_set = 0;
547 /* Return 1 if TYPE1 and TYPE2 are to be considered equivalent for the
548 purpose of TBAA. Return 0 if they are distinct and -1 if we cannot
552 same_type_for_tbaa (tree type1, tree type2)
554 type1 = TYPE_MAIN_VARIANT (type1);
555 type2 = TYPE_MAIN_VARIANT (type2);
557 /* If we would have to do structural comparison bail out. */
558 if (TYPE_STRUCTURAL_EQUALITY_P (type1)
559 || TYPE_STRUCTURAL_EQUALITY_P (type2))
562 /* Compare the canonical types. */
563 if (TYPE_CANONICAL (type1) == TYPE_CANONICAL (type2))
566 /* ??? Array types are not properly unified in all cases as we have
567 spurious changes in the index types for example. Removing this
568 causes all sorts of problems with the Fortran frontend. */
569 if (TREE_CODE (type1) == ARRAY_TYPE
570 && TREE_CODE (type2) == ARRAY_TYPE)
573 /* ??? In Ada, an lvalue of an unconstrained type can be used to access an
574 object of one of its constrained subtypes, e.g. when a function with an
575 unconstrained parameter passed by reference is called on an object and
576 inlined. But, even in the case of a fixed size, type and subtypes are
577 not equivalent enough as to share the same TYPE_CANONICAL, since this
578 would mean that conversions between them are useless, whereas they are
579 not (e.g. type and subtypes can have different modes). So, in the end,
580 they are only guaranteed to have the same alias set. */
581 if (get_alias_set (type1) == get_alias_set (type2))
584 /* The types are known to be not equal. */
588 /* Determine if the two component references REF1 and REF2 which are
589 based on access types TYPE1 and TYPE2 and of which at least one is based
590 on an indirect reference may alias. REF2 is the only one that can
591 be a decl in which case REF2_IS_DECL is true.
592 REF1_ALIAS_SET, BASE1_ALIAS_SET, REF2_ALIAS_SET and BASE2_ALIAS_SET
593 are the respective alias sets. */
596 aliasing_component_refs_p (tree ref1, tree type1,
597 alias_set_type ref1_alias_set,
598 alias_set_type base1_alias_set,
599 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
600 tree ref2, tree type2,
601 alias_set_type ref2_alias_set,
602 alias_set_type base2_alias_set,
603 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
606 /* If one reference is a component references through pointers try to find a
607 common base and apply offset based disambiguation. This handles
609 struct A { int i; int j; } *q;
610 struct B { struct A a; int k; } *p;
611 disambiguating q->i and p->a.j. */
615 /* Now search for the type1 in the access path of ref2. This
616 would be a common base for doing offset based disambiguation on. */
618 while (handled_component_p (*refp)
619 && same_type_for_tbaa (TREE_TYPE (*refp), type1) == 0)
620 refp = &TREE_OPERAND (*refp, 0);
621 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type1);
622 /* If we couldn't compare types we have to bail out. */
625 else if (same_p == 1)
627 HOST_WIDE_INT offadj, sztmp, msztmp;
628 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
630 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
632 /* If we didn't find a common base, try the other way around. */
634 while (handled_component_p (*refp)
635 && same_type_for_tbaa (TREE_TYPE (*refp), type2) == 0)
636 refp = &TREE_OPERAND (*refp, 0);
637 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type2);
638 /* If we couldn't compare types we have to bail out. */
641 else if (same_p == 1)
643 HOST_WIDE_INT offadj, sztmp, msztmp;
644 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
646 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
649 /* If we have two type access paths B1.path1 and B2.path2 they may
650 only alias if either B1 is in B2.path2 or B2 is in B1.path1.
651 But we can still have a path that goes B1.path1...B2.path2 with
652 a part that we do not see. So we can only disambiguate now
653 if there is no B2 in the tail of path1 and no B1 on the
655 if (base1_alias_set == ref2_alias_set
656 || alias_set_subset_of (base1_alias_set, ref2_alias_set))
658 /* If this is ptr vs. decl then we know there is no ptr ... decl path. */
660 return (base2_alias_set == ref1_alias_set
661 || alias_set_subset_of (base2_alias_set, ref1_alias_set));
665 /* Return true if two memory references based on the variables BASE1
666 and BASE2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
667 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. */
670 decl_refs_may_alias_p (tree base1,
671 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
673 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
675 gcc_assert (SSA_VAR_P (base1) && SSA_VAR_P (base2));
677 /* If both references are based on different variables, they cannot alias. */
681 /* If both references are based on the same variable, they cannot alias if
682 the accesses do not overlap. */
683 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
686 /* Return true if an indirect reference based on *PTR1 constrained
687 to [OFFSET1, OFFSET1 + MAX_SIZE1) may alias a variable based on BASE2
688 constrained to [OFFSET2, OFFSET2 + MAX_SIZE2). *PTR1 and BASE2 have
689 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
690 in which case they are computed on-demand. REF1 and REF2
691 if non-NULL are the complete memory reference trees. */
694 indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
695 HOST_WIDE_INT offset1,
696 HOST_WIDE_INT max_size1 ATTRIBUTE_UNUSED,
697 alias_set_type ref1_alias_set,
698 alias_set_type base1_alias_set,
699 tree ref2 ATTRIBUTE_UNUSED, tree base2,
700 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
701 alias_set_type ref2_alias_set,
702 alias_set_type base2_alias_set, bool tbaa_p)
706 HOST_WIDE_INT offset1p = offset1, offset2p = offset2;
708 ptr1 = TREE_OPERAND (base1, 0);
710 /* The offset embedded in MEM_REFs can be negative. Bias them
711 so that the resulting offset adjustment is positive. */
712 if (TREE_CODE (base1) == MEM_REF
713 || TREE_CODE (base1) == TARGET_MEM_REF)
715 double_int moff = mem_ref_offset (base1);
716 moff = double_int_lshift (moff,
718 ? 3 : exact_log2 (BITS_PER_UNIT),
719 HOST_BITS_PER_DOUBLE_INT, true);
720 if (double_int_negative_p (moff))
721 offset2p += double_int_neg (moff).low;
723 offset1p += moff.low;
726 /* If only one reference is based on a variable, they cannot alias if
727 the pointer access is beyond the extent of the variable access.
728 (the pointer base cannot validly point to an offset less than zero
730 They also cannot alias if the pointer may not point to the decl. */
731 if ((TREE_CODE (base1) != TARGET_MEM_REF
732 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
733 && !ranges_overlap_p (MAX (0, offset1p), -1, offset2p, max_size2))
735 if (!ptr_deref_may_alias_decl_p (ptr1, base2))
738 /* Disambiguations that rely on strict aliasing rules follow. */
739 if (!flag_strict_aliasing || !tbaa_p)
742 if (TREE_CODE (base1) == MEM_REF)
743 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
744 else if (TREE_CODE (base1) == TARGET_MEM_REF)
745 ptrtype1 = TREE_TYPE (TMR_OFFSET (base1));
747 ptrtype1 = TREE_TYPE (ptr1);
749 /* If the alias set for a pointer access is zero all bets are off. */
750 if (base1_alias_set == -1)
751 base1_alias_set = get_deref_alias_set (ptrtype1);
752 if (base1_alias_set == 0)
754 if (base2_alias_set == -1)
755 base2_alias_set = get_alias_set (base2);
757 /* If both references are through the same type, they do not alias
758 if the accesses do not overlap. This does extra disambiguation
759 for mixed/pointer accesses but requires strict aliasing.
760 For MEM_REFs we require that the component-ref offset we computed
761 is relative to the start of the type which we ensure by
762 comparing rvalue and access type and disregarding the constant
764 if ((TREE_CODE (base1) != TARGET_MEM_REF
765 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
766 && (TREE_CODE (base1) != MEM_REF
767 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
768 && same_type_for_tbaa (TREE_TYPE (ptrtype1), TREE_TYPE (base2)) == 1)
769 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
771 /* When we are trying to disambiguate an access with a pointer dereference
772 as base versus one with a decl as base we can use both the size
773 of the decl and its dynamic type for extra disambiguation.
774 ??? We do not know anything about the dynamic type of the decl
775 other than that its alias-set contains base2_alias_set as a subset
776 which does not help us here. */
777 /* As we know nothing useful about the dynamic type of the decl just
778 use the usual conflict check rather than a subset test.
779 ??? We could introduce -fvery-strict-aliasing when the language
780 does not allow decls to have a dynamic type that differs from their
781 static type. Then we can check
782 !alias_set_subset_of (base1_alias_set, base2_alias_set) instead. */
783 if (base1_alias_set != base2_alias_set
784 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
786 /* If the size of the access relevant for TBAA through the pointer
787 is bigger than the size of the decl we can't possibly access the
788 decl via that pointer. */
789 if (DECL_SIZE (base2) && COMPLETE_TYPE_P (TREE_TYPE (ptrtype1))
790 && TREE_CODE (DECL_SIZE (base2)) == INTEGER_CST
791 && TREE_CODE (TYPE_SIZE (TREE_TYPE (ptrtype1))) == INTEGER_CST
792 /* ??? This in turn may run afoul when a decl of type T which is
793 a member of union type U is accessed through a pointer to
794 type U and sizeof T is smaller than sizeof U. */
795 && TREE_CODE (TREE_TYPE (ptrtype1)) != UNION_TYPE
796 && TREE_CODE (TREE_TYPE (ptrtype1)) != QUAL_UNION_TYPE
797 && tree_int_cst_lt (DECL_SIZE (base2), TYPE_SIZE (TREE_TYPE (ptrtype1))))
800 /* Do access-path based disambiguation. */
802 && handled_component_p (ref1)
803 && handled_component_p (ref2)
804 && TREE_CODE (base1) != TARGET_MEM_REF
805 && (TREE_CODE (base1) != MEM_REF
806 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1))
807 return aliasing_component_refs_p (ref1, TREE_TYPE (ptrtype1),
808 ref1_alias_set, base1_alias_set,
811 (reference_alias_ptr_type (ref2)),
812 ref2_alias_set, base2_alias_set,
813 offset2, max_size2, true);
818 /* Return true if two indirect references based on *PTR1
819 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
820 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have
821 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
822 in which case they are computed on-demand. REF1 and REF2
823 if non-NULL are the complete memory reference trees. */
826 indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
827 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
828 alias_set_type ref1_alias_set,
829 alias_set_type base1_alias_set,
830 tree ref2 ATTRIBUTE_UNUSED, tree base2,
831 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
832 alias_set_type ref2_alias_set,
833 alias_set_type base2_alias_set, bool tbaa_p)
837 tree ptrtype1, ptrtype2;
839 ptr1 = TREE_OPERAND (base1, 0);
840 ptr2 = TREE_OPERAND (base2, 0);
842 /* If both bases are based on pointers they cannot alias if they may not
843 point to the same memory object or if they point to the same object
844 and the accesses do not overlap. */
845 if ((!cfun || gimple_in_ssa_p (cfun))
846 && operand_equal_p (ptr1, ptr2, 0)
847 && (((TREE_CODE (base1) != TARGET_MEM_REF
848 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
849 && (TREE_CODE (base2) != TARGET_MEM_REF
850 || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2))))
851 || (TREE_CODE (base1) == TARGET_MEM_REF
852 && TREE_CODE (base2) == TARGET_MEM_REF
853 && (TMR_STEP (base1) == TMR_STEP (base2)
854 || (TMR_STEP (base1) && TMR_STEP (base2)
855 && operand_equal_p (TMR_STEP (base1),
856 TMR_STEP (base2), 0)))
857 && (TMR_INDEX (base1) == TMR_INDEX (base2)
858 || (TMR_INDEX (base1) && TMR_INDEX (base2)
859 && operand_equal_p (TMR_INDEX (base1),
860 TMR_INDEX (base2), 0)))
861 && (TMR_INDEX2 (base1) == TMR_INDEX2 (base2)
862 || (TMR_INDEX2 (base1) && TMR_INDEX2 (base2)
863 && operand_equal_p (TMR_INDEX2 (base1),
864 TMR_INDEX2 (base2), 0))))))
866 /* The offset embedded in MEM_REFs can be negative. Bias them
867 so that the resulting offset adjustment is positive. */
868 if (TREE_CODE (base1) == MEM_REF
869 || TREE_CODE (base1) == TARGET_MEM_REF)
871 double_int moff = mem_ref_offset (base1);
872 moff = double_int_lshift (moff,
874 ? 3 : exact_log2 (BITS_PER_UNIT),
875 HOST_BITS_PER_DOUBLE_INT, true);
876 if (double_int_negative_p (moff))
877 offset2 += double_int_neg (moff).low;
881 if (TREE_CODE (base2) == MEM_REF
882 || TREE_CODE (base2) == TARGET_MEM_REF)
884 double_int moff = mem_ref_offset (base2);
885 moff = double_int_lshift (moff,
887 ? 3 : exact_log2 (BITS_PER_UNIT),
888 HOST_BITS_PER_DOUBLE_INT, true);
889 if (double_int_negative_p (moff))
890 offset1 += double_int_neg (moff).low;
894 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
896 if (!ptr_derefs_may_alias_p (ptr1, ptr2))
899 /* Disambiguations that rely on strict aliasing rules follow. */
900 if (!flag_strict_aliasing || !tbaa_p)
903 if (TREE_CODE (base1) == MEM_REF)
904 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
905 else if (TREE_CODE (base1) == TARGET_MEM_REF)
906 ptrtype1 = TREE_TYPE (TMR_OFFSET (base1));
908 ptrtype1 = TREE_TYPE (ptr1);
909 if (TREE_CODE (base2) == MEM_REF)
910 ptrtype2 = TREE_TYPE (TREE_OPERAND (base2, 1));
911 else if (TREE_CODE (base2) == TARGET_MEM_REF)
912 ptrtype2 = TREE_TYPE (TMR_OFFSET (base2));
914 ptrtype2 = TREE_TYPE (ptr2);
916 /* If the alias set for a pointer access is zero all bets are off. */
917 if (base1_alias_set == -1)
918 base1_alias_set = get_deref_alias_set (ptrtype1);
919 if (base1_alias_set == 0)
921 if (base2_alias_set == -1)
922 base2_alias_set = get_deref_alias_set (ptrtype2);
923 if (base2_alias_set == 0)
926 /* If both references are through the same type, they do not alias
927 if the accesses do not overlap. This does extra disambiguation
928 for mixed/pointer accesses but requires strict aliasing. */
929 if ((TREE_CODE (base1) != TARGET_MEM_REF || !TMR_INDEX (base1))
930 && (TREE_CODE (base2) != TARGET_MEM_REF || !TMR_INDEX (base2))
931 && (TREE_CODE (base1) != MEM_REF
932 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
933 && (TREE_CODE (base2) != MEM_REF
934 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1)
935 && same_type_for_tbaa (TREE_TYPE (ptrtype1),
936 TREE_TYPE (ptrtype2)) == 1)
937 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
939 /* Do type-based disambiguation. */
940 if (base1_alias_set != base2_alias_set
941 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
944 /* Do access-path based disambiguation. */
946 && handled_component_p (ref1)
947 && handled_component_p (ref2)
948 && TREE_CODE (base1) != TARGET_MEM_REF
949 && TREE_CODE (base2) != TARGET_MEM_REF
950 && (TREE_CODE (base1) != MEM_REF
951 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
952 && (TREE_CODE (base2) != MEM_REF
953 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1))
954 return aliasing_component_refs_p (ref1, TREE_TYPE (ptrtype1),
955 ref1_alias_set, base1_alias_set,
957 ref2, TREE_TYPE (ptrtype2),
958 ref2_alias_set, base2_alias_set,
959 offset2, max_size2, false);
964 /* Return true, if the two memory references REF1 and REF2 may alias. */
967 refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
970 HOST_WIDE_INT offset1 = 0, offset2 = 0;
971 HOST_WIDE_INT max_size1 = -1, max_size2 = -1;
972 bool var1_p, var2_p, ind1_p, ind2_p;
974 gcc_checking_assert ((!ref1->ref
975 || TREE_CODE (ref1->ref) == SSA_NAME
976 || DECL_P (ref1->ref)
977 || TREE_CODE (ref1->ref) == STRING_CST
978 || handled_component_p (ref1->ref)
979 || INDIRECT_REF_P (ref1->ref)
980 || TREE_CODE (ref1->ref) == MEM_REF
981 || TREE_CODE (ref1->ref) == TARGET_MEM_REF)
983 || TREE_CODE (ref2->ref) == SSA_NAME
984 || DECL_P (ref2->ref)
985 || TREE_CODE (ref2->ref) == STRING_CST
986 || handled_component_p (ref2->ref)
987 || INDIRECT_REF_P (ref2->ref)
988 || TREE_CODE (ref2->ref) == MEM_REF
989 || TREE_CODE (ref2->ref) == TARGET_MEM_REF));
991 /* Decompose the references into their base objects and the access. */
992 base1 = ao_ref_base (ref1);
993 offset1 = ref1->offset;
994 max_size1 = ref1->max_size;
995 base2 = ao_ref_base (ref2);
996 offset2 = ref2->offset;
997 max_size2 = ref2->max_size;
999 /* We can end up with registers or constants as bases for example from
1000 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
1001 which is seen as a struct copy. */
1002 if (TREE_CODE (base1) == SSA_NAME
1003 || TREE_CODE (base1) == CONST_DECL
1004 || TREE_CODE (base1) == CONSTRUCTOR
1005 || TREE_CODE (base1) == ADDR_EXPR
1006 || CONSTANT_CLASS_P (base1)
1007 || TREE_CODE (base2) == SSA_NAME
1008 || TREE_CODE (base2) == CONST_DECL
1009 || TREE_CODE (base2) == CONSTRUCTOR
1010 || TREE_CODE (base2) == ADDR_EXPR
1011 || CONSTANT_CLASS_P (base2))
1014 /* We can end up refering to code via function and label decls.
1015 As we likely do not properly track code aliases conservatively
1017 if (TREE_CODE (base1) == FUNCTION_DECL
1018 || TREE_CODE (base1) == LABEL_DECL
1019 || TREE_CODE (base2) == FUNCTION_DECL
1020 || TREE_CODE (base2) == LABEL_DECL)
1023 /* Defer to simple offset based disambiguation if we have
1024 references based on two decls. Do this before defering to
1025 TBAA to handle must-alias cases in conformance with the
1026 GCC extension of allowing type-punning through unions. */
1027 var1_p = SSA_VAR_P (base1);
1028 var2_p = SSA_VAR_P (base2);
1029 if (var1_p && var2_p)
1030 return decl_refs_may_alias_p (base1, offset1, max_size1,
1031 base2, offset2, max_size2);
1033 ind1_p = (INDIRECT_REF_P (base1)
1034 || (TREE_CODE (base1) == MEM_REF)
1035 || (TREE_CODE (base1) == TARGET_MEM_REF));
1036 ind2_p = (INDIRECT_REF_P (base2)
1037 || (TREE_CODE (base2) == MEM_REF)
1038 || (TREE_CODE (base2) == TARGET_MEM_REF));
1040 /* Canonicalize the pointer-vs-decl case. */
1041 if (ind1_p && var2_p)
1046 tmp1 = offset1; offset1 = offset2; offset2 = tmp1;
1047 tmp1 = max_size1; max_size1 = max_size2; max_size2 = tmp1;
1048 tmp2 = base1; base1 = base2; base2 = tmp2;
1049 tmp3 = ref1; ref1 = ref2; ref2 = tmp3;
1056 /* First defer to TBAA if possible. */
1058 && flag_strict_aliasing
1059 && !alias_sets_conflict_p (ao_ref_alias_set (ref1),
1060 ao_ref_alias_set (ref2)))
1063 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */
1064 if (var1_p && ind2_p)
1065 return indirect_ref_may_alias_decl_p (ref2->ref, base2,
1067 ao_ref_alias_set (ref2), -1,
1070 ao_ref_alias_set (ref1),
1071 ao_ref_base_alias_set (ref1),
1073 else if (ind1_p && ind2_p)
1074 return indirect_refs_may_alias_p (ref1->ref, base1,
1076 ao_ref_alias_set (ref1), -1,
1079 ao_ref_alias_set (ref2), -1,
1082 /* We really do not want to end up here, but returning true is safe. */
1083 #ifdef ENABLE_CHECKING
1091 refs_may_alias_p (tree ref1, tree ref2)
1095 ao_ref_init (&r1, ref1);
1096 ao_ref_init (&r2, ref2);
1097 res = refs_may_alias_p_1 (&r1, &r2, true);
1099 ++alias_stats.refs_may_alias_p_may_alias;
1101 ++alias_stats.refs_may_alias_p_no_alias;
1105 /* Returns true if there is a anti-dependence for the STORE that
1106 executes after the LOAD. */
1109 refs_anti_dependent_p (tree load, tree store)
1112 ao_ref_init (&r1, load);
1113 ao_ref_init (&r2, store);
1114 return refs_may_alias_p_1 (&r1, &r2, false);
1117 /* Returns true if there is a output dependence for the stores
1118 STORE1 and STORE2. */
1121 refs_output_dependent_p (tree store1, tree store2)
1124 ao_ref_init (&r1, store1);
1125 ao_ref_init (&r2, store2);
1126 return refs_may_alias_p_1 (&r1, &r2, false);
1129 /* If the call CALL may use the memory reference REF return true,
1130 otherwise return false. */
1133 ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
1137 int flags = gimple_call_flags (call);
1139 /* Const functions without a static chain do not implicitly use memory. */
1140 if (!gimple_call_chain (call)
1141 && (flags & (ECF_CONST|ECF_NOVOPS)))
1144 base = ao_ref_base (ref);
1148 /* If the reference is based on a decl that is not aliased the call
1149 cannot possibly use it. */
1151 && !may_be_aliased (base)
1152 /* But local statics can be used through recursion. */
1153 && !is_global_var (base))
1156 callee = gimple_call_fndecl (call);
1158 /* Handle those builtin functions explicitly that do not act as
1159 escape points. See tree-ssa-structalias.c:find_func_aliases
1160 for the list of builtins we might need to handle here. */
1161 if (callee != NULL_TREE
1162 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1163 switch (DECL_FUNCTION_CODE (callee))
1165 /* All the following functions clobber memory pointed to by
1166 their first argument. */
1167 case BUILT_IN_STRCPY:
1168 case BUILT_IN_STRNCPY:
1169 case BUILT_IN_MEMCPY:
1170 case BUILT_IN_MEMMOVE:
1171 case BUILT_IN_MEMPCPY:
1172 case BUILT_IN_STPCPY:
1173 case BUILT_IN_STPNCPY:
1174 case BUILT_IN_STRCAT:
1175 case BUILT_IN_STRNCAT:
1178 tree size = NULL_TREE;
1179 if (gimple_call_num_args (call) == 3)
1180 size = gimple_call_arg (call, 2);
1181 ao_ref_init_from_ptr_and_size (&dref,
1182 gimple_call_arg (call, 1),
1184 return refs_may_alias_p_1 (&dref, ref, false);
1186 case BUILT_IN_BCOPY:
1189 tree size = gimple_call_arg (call, 2);
1190 ao_ref_init_from_ptr_and_size (&dref,
1191 gimple_call_arg (call, 0),
1193 return refs_may_alias_p_1 (&dref, ref, false);
1195 /* The following builtins do not read from memory. */
1197 case BUILT_IN_MALLOC:
1198 case BUILT_IN_CALLOC:
1199 case BUILT_IN_ALLOCA:
1200 case BUILT_IN_STACK_SAVE:
1201 case BUILT_IN_STACK_RESTORE:
1202 case BUILT_IN_MEMSET:
1203 case BUILT_IN_FREXP:
1204 case BUILT_IN_FREXPF:
1205 case BUILT_IN_FREXPL:
1206 case BUILT_IN_GAMMA_R:
1207 case BUILT_IN_GAMMAF_R:
1208 case BUILT_IN_GAMMAL_R:
1209 case BUILT_IN_LGAMMA_R:
1210 case BUILT_IN_LGAMMAF_R:
1211 case BUILT_IN_LGAMMAL_R:
1213 case BUILT_IN_MODFF:
1214 case BUILT_IN_MODFL:
1215 case BUILT_IN_REMQUO:
1216 case BUILT_IN_REMQUOF:
1217 case BUILT_IN_REMQUOL:
1218 case BUILT_IN_SINCOS:
1219 case BUILT_IN_SINCOSF:
1220 case BUILT_IN_SINCOSL:
1222 /* __sync_* builtins and some OpenMP builtins act as threading
1224 #undef DEF_SYNC_BUILTIN
1225 #define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM:
1226 #include "sync-builtins.def"
1227 #undef DEF_SYNC_BUILTIN
1228 case BUILT_IN_GOMP_ATOMIC_START:
1229 case BUILT_IN_GOMP_ATOMIC_END:
1230 case BUILT_IN_GOMP_BARRIER:
1231 case BUILT_IN_GOMP_TASKWAIT:
1232 case BUILT_IN_GOMP_CRITICAL_START:
1233 case BUILT_IN_GOMP_CRITICAL_END:
1234 case BUILT_IN_GOMP_CRITICAL_NAME_START:
1235 case BUILT_IN_GOMP_CRITICAL_NAME_END:
1236 case BUILT_IN_GOMP_LOOP_END:
1237 case BUILT_IN_GOMP_ORDERED_START:
1238 case BUILT_IN_GOMP_ORDERED_END:
1239 case BUILT_IN_GOMP_PARALLEL_END:
1240 case BUILT_IN_GOMP_SECTIONS_END:
1241 case BUILT_IN_GOMP_SINGLE_COPY_START:
1242 case BUILT_IN_GOMP_SINGLE_COPY_END:
1246 /* Fallthru to general call handling. */;
1249 /* Check if base is a global static variable that is not read
1251 if (callee != NULL_TREE
1252 && TREE_CODE (base) == VAR_DECL
1253 && TREE_STATIC (base))
1255 struct cgraph_node *node = cgraph_get_node (callee);
1258 /* FIXME: Callee can be an OMP builtin that does not have a call graph
1259 node yet. We should enforce that there are nodes for all decls in the
1260 IL and remove this check instead. */
1262 && (not_read = ipa_reference_get_not_read_global (node))
1263 && bitmap_bit_p (not_read, DECL_UID (base)))
1267 /* Check if the base variable is call-used. */
1270 if (pt_solution_includes (gimple_call_use_set (call), base))
1273 else if ((INDIRECT_REF_P (base)
1274 || TREE_CODE (base) == MEM_REF)
1275 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1277 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1281 if (pt_solutions_intersect (gimple_call_use_set (call), &pi->pt))
1287 /* Inspect call arguments for passed-by-value aliases. */
1289 for (i = 0; i < gimple_call_num_args (call); ++i)
1291 tree op = gimple_call_arg (call, i);
1292 int flags = gimple_call_arg_flags (call, i);
1294 if (flags & EAF_UNUSED)
1297 if (TREE_CODE (op) == WITH_SIZE_EXPR)
1298 op = TREE_OPERAND (op, 0);
1300 if (TREE_CODE (op) != SSA_NAME
1301 && !is_gimple_min_invariant (op))
1304 ao_ref_init (&r, op);
1305 if (refs_may_alias_p_1 (&r, ref, true))
1314 ref_maybe_used_by_call_p (gimple call, tree ref)
1318 ao_ref_init (&r, ref);
1319 res = ref_maybe_used_by_call_p_1 (call, &r);
1321 ++alias_stats.ref_maybe_used_by_call_p_may_alias;
1323 ++alias_stats.ref_maybe_used_by_call_p_no_alias;
1328 /* If the statement STMT may use the memory reference REF return
1329 true, otherwise return false. */
1332 ref_maybe_used_by_stmt_p (gimple stmt, tree ref)
1334 if (is_gimple_assign (stmt))
1338 /* All memory assign statements are single. */
1339 if (!gimple_assign_single_p (stmt))
1342 rhs = gimple_assign_rhs1 (stmt);
1343 if (is_gimple_reg (rhs)
1344 || is_gimple_min_invariant (rhs)
1345 || gimple_assign_rhs_code (stmt) == CONSTRUCTOR)
1348 return refs_may_alias_p (rhs, ref);
1350 else if (is_gimple_call (stmt))
1351 return ref_maybe_used_by_call_p (stmt, ref);
1356 /* If the call in statement CALL may clobber the memory reference REF
1357 return true, otherwise return false. */
1360 call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
1365 /* If the call is pure or const it cannot clobber anything. */
1366 if (gimple_call_flags (call)
1367 & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS))
1370 base = ao_ref_base (ref);
1374 if (TREE_CODE (base) == SSA_NAME
1375 || CONSTANT_CLASS_P (base))
1378 /* If the reference is based on a decl that is not aliased the call
1379 cannot possibly clobber it. */
1381 && !may_be_aliased (base)
1382 /* But local non-readonly statics can be modified through recursion
1383 or the call may implement a threading barrier which we must
1384 treat as may-def. */
1385 && (TREE_READONLY (base)
1386 || !is_global_var (base)))
1389 callee = gimple_call_fndecl (call);
1391 /* Handle those builtin functions explicitly that do not act as
1392 escape points. See tree-ssa-structalias.c:find_func_aliases
1393 for the list of builtins we might need to handle here. */
1394 if (callee != NULL_TREE
1395 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1396 switch (DECL_FUNCTION_CODE (callee))
1398 /* All the following functions clobber memory pointed to by
1399 their first argument. */
1400 case BUILT_IN_STRCPY:
1401 case BUILT_IN_STRNCPY:
1402 case BUILT_IN_MEMCPY:
1403 case BUILT_IN_MEMMOVE:
1404 case BUILT_IN_MEMPCPY:
1405 case BUILT_IN_STPCPY:
1406 case BUILT_IN_STPNCPY:
1407 case BUILT_IN_STRCAT:
1408 case BUILT_IN_STRNCAT:
1409 case BUILT_IN_MEMSET:
1412 tree size = NULL_TREE;
1413 if (gimple_call_num_args (call) == 3)
1414 size = gimple_call_arg (call, 2);
1415 ao_ref_init_from_ptr_and_size (&dref,
1416 gimple_call_arg (call, 0),
1418 return refs_may_alias_p_1 (&dref, ref, false);
1420 case BUILT_IN_BCOPY:
1423 tree size = gimple_call_arg (call, 2);
1424 ao_ref_init_from_ptr_and_size (&dref,
1425 gimple_call_arg (call, 1),
1427 return refs_may_alias_p_1 (&dref, ref, false);
1429 /* Allocating memory does not have any side-effects apart from
1430 being the definition point for the pointer. */
1431 case BUILT_IN_MALLOC:
1432 case BUILT_IN_CALLOC:
1433 /* Unix98 specifies that errno is set on allocation failure. */
1435 && targetm.ref_may_alias_errno (ref))
1438 case BUILT_IN_STACK_SAVE:
1439 case BUILT_IN_ALLOCA:
1441 /* Freeing memory kills the pointed-to memory. More importantly
1442 the call has to serve as a barrier for moving loads and stores
1446 tree ptr = gimple_call_arg (call, 0);
1447 return ptr_deref_may_alias_ref_p_1 (ptr, ref);
1449 case BUILT_IN_GAMMA_R:
1450 case BUILT_IN_GAMMAF_R:
1451 case BUILT_IN_GAMMAL_R:
1452 case BUILT_IN_LGAMMA_R:
1453 case BUILT_IN_LGAMMAF_R:
1454 case BUILT_IN_LGAMMAL_R:
1456 tree out = gimple_call_arg (call, 1);
1457 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1459 if (flag_errno_math)
1463 case BUILT_IN_FREXP:
1464 case BUILT_IN_FREXPF:
1465 case BUILT_IN_FREXPL:
1467 case BUILT_IN_MODFF:
1468 case BUILT_IN_MODFL:
1470 tree out = gimple_call_arg (call, 1);
1471 return ptr_deref_may_alias_ref_p_1 (out, ref);
1473 case BUILT_IN_REMQUO:
1474 case BUILT_IN_REMQUOF:
1475 case BUILT_IN_REMQUOL:
1477 tree out = gimple_call_arg (call, 2);
1478 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1480 if (flag_errno_math)
1484 case BUILT_IN_SINCOS:
1485 case BUILT_IN_SINCOSF:
1486 case BUILT_IN_SINCOSL:
1488 tree sin = gimple_call_arg (call, 1);
1489 tree cos = gimple_call_arg (call, 2);
1490 return (ptr_deref_may_alias_ref_p_1 (sin, ref)
1491 || ptr_deref_may_alias_ref_p_1 (cos, ref));
1493 /* __sync_* builtins and some OpenMP builtins act as threading
1495 #undef DEF_SYNC_BUILTIN
1496 #define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM:
1497 #include "sync-builtins.def"
1498 #undef DEF_SYNC_BUILTIN
1499 case BUILT_IN_GOMP_ATOMIC_START:
1500 case BUILT_IN_GOMP_ATOMIC_END:
1501 case BUILT_IN_GOMP_BARRIER:
1502 case BUILT_IN_GOMP_TASKWAIT:
1503 case BUILT_IN_GOMP_CRITICAL_START:
1504 case BUILT_IN_GOMP_CRITICAL_END:
1505 case BUILT_IN_GOMP_CRITICAL_NAME_START:
1506 case BUILT_IN_GOMP_CRITICAL_NAME_END:
1507 case BUILT_IN_GOMP_LOOP_END:
1508 case BUILT_IN_GOMP_ORDERED_START:
1509 case BUILT_IN_GOMP_ORDERED_END:
1510 case BUILT_IN_GOMP_PARALLEL_END:
1511 case BUILT_IN_GOMP_SECTIONS_END:
1512 case BUILT_IN_GOMP_SINGLE_COPY_START:
1513 case BUILT_IN_GOMP_SINGLE_COPY_END:
1516 /* Fallthru to general call handling. */;
1519 /* Check if base is a global static variable that is not written
1521 if (callee != NULL_TREE
1522 && TREE_CODE (base) == VAR_DECL
1523 && TREE_STATIC (base))
1525 struct cgraph_node *node = cgraph_get_node (callee);
1529 && (not_written = ipa_reference_get_not_written_global (node))
1530 && bitmap_bit_p (not_written, DECL_UID (base)))
1534 /* Check if the base variable is call-clobbered. */
1536 return pt_solution_includes (gimple_call_clobber_set (call), base);
1537 else if ((INDIRECT_REF_P (base)
1538 || TREE_CODE (base) == MEM_REF)
1539 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1541 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1545 return pt_solutions_intersect (gimple_call_clobber_set (call), &pi->pt);
1551 /* If the call in statement CALL may clobber the memory reference REF
1552 return true, otherwise return false. */
1555 call_may_clobber_ref_p (gimple call, tree ref)
1559 ao_ref_init (&r, ref);
1560 res = call_may_clobber_ref_p_1 (call, &r);
1562 ++alias_stats.call_may_clobber_ref_p_may_alias;
1564 ++alias_stats.call_may_clobber_ref_p_no_alias;
1569 /* If the statement STMT may clobber the memory reference REF return true,
1570 otherwise return false. */
1573 stmt_may_clobber_ref_p_1 (gimple stmt, ao_ref *ref)
1575 if (is_gimple_call (stmt))
1577 tree lhs = gimple_call_lhs (stmt);
1579 && TREE_CODE (lhs) != SSA_NAME)
1582 ao_ref_init (&r, lhs);
1583 if (refs_may_alias_p_1 (ref, &r, true))
1587 return call_may_clobber_ref_p_1 (stmt, ref);
1589 else if (gimple_assign_single_p (stmt))
1591 tree lhs = gimple_assign_lhs (stmt);
1592 if (TREE_CODE (lhs) != SSA_NAME)
1595 ao_ref_init (&r, lhs);
1596 return refs_may_alias_p_1 (ref, &r, true);
1599 else if (gimple_code (stmt) == GIMPLE_ASM)
1606 stmt_may_clobber_ref_p (gimple stmt, tree ref)
1609 ao_ref_init (&r, ref);
1610 return stmt_may_clobber_ref_p_1 (stmt, &r);
1613 /* If STMT kills the memory reference REF return true, otherwise
1617 stmt_kills_ref_p_1 (gimple stmt, ao_ref *ref)
1619 if (gimple_has_lhs (stmt)
1620 && TREE_CODE (gimple_get_lhs (stmt)) != SSA_NAME)
1622 tree base, lhs = gimple_get_lhs (stmt);
1623 HOST_WIDE_INT size, offset, max_size;
1625 base = get_ref_base_and_extent (lhs, &offset, &size, &max_size);
1626 /* We can get MEM[symbol: sZ, index: D.8862_1] here,
1627 so base == ref->base does not always hold. */
1628 if (base == ref->base)
1630 /* For a must-alias check we need to be able to constrain
1631 the accesses properly. */
1632 if (size != -1 && size == max_size
1633 && ref->max_size != -1)
1635 if (offset <= ref->offset
1636 && offset + size >= ref->offset + ref->max_size)
1645 stmt_kills_ref_p (gimple stmt, tree ref)
1648 ao_ref_init (&r, ref);
1649 return stmt_kills_ref_p_1 (stmt, &r);
1653 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand
1654 TARGET or a statement clobbering the memory reference REF in which
1655 case false is returned. The walk starts with VUSE, one argument of PHI. */
1658 maybe_skip_until (gimple phi, tree target, ao_ref *ref,
1659 tree vuse, bitmap *visited)
1662 *visited = BITMAP_ALLOC (NULL);
1664 bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi)));
1666 /* Walk until we hit the target. */
1667 while (vuse != target)
1669 gimple def_stmt = SSA_NAME_DEF_STMT (vuse);
1670 /* Recurse for PHI nodes. */
1671 if (gimple_code (def_stmt) == GIMPLE_PHI)
1673 /* An already visited PHI node ends the walk successfully. */
1674 if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt))))
1676 vuse = get_continuation_for_phi (def_stmt, ref, visited);
1681 /* A clobbering statement or the end of the IL ends it failing. */
1682 else if (gimple_nop_p (def_stmt)
1683 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1685 vuse = gimple_vuse (def_stmt);
1690 /* Starting from a PHI node for the virtual operand of the memory reference
1691 REF find a continuation virtual operand that allows to continue walking
1692 statements dominating PHI skipping only statements that cannot possibly
1693 clobber REF. Returns NULL_TREE if no suitable virtual operand can
1697 get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited)
1699 unsigned nargs = gimple_phi_num_args (phi);
1701 /* Through a single-argument PHI we can simply look through. */
1703 return PHI_ARG_DEF (phi, 0);
1705 /* For two arguments try to skip non-aliasing code until we hit
1706 the phi argument definition that dominates the other one. */
1709 tree arg0 = PHI_ARG_DEF (phi, 0);
1710 tree arg1 = PHI_ARG_DEF (phi, 1);
1711 gimple def0 = SSA_NAME_DEF_STMT (arg0);
1712 gimple def1 = SSA_NAME_DEF_STMT (arg1);
1717 else if (gimple_nop_p (def0)
1718 || (!gimple_nop_p (def1)
1719 && dominated_by_p (CDI_DOMINATORS,
1720 gimple_bb (def1), gimple_bb (def0))))
1722 if (maybe_skip_until (phi, arg0, ref, arg1, visited))
1725 else if (gimple_nop_p (def1)
1726 || dominated_by_p (CDI_DOMINATORS,
1727 gimple_bb (def0), gimple_bb (def1)))
1729 if (maybe_skip_until (phi, arg1, ref, arg0, visited))
1732 /* Special case of a diamond:
1734 goto (cond) ? L1 : L2
1735 L1: store1 = ... #MEM_2 = vuse(MEM_1)
1737 L2: store2 = ... #MEM_3 = vuse(MEM_1)
1738 L3: MEM_4 = PHI<MEM_2, MEM_3>
1739 We were called with the PHI at L3, MEM_2 and MEM_3 don't
1740 dominate each other, but still we can easily skip this PHI node
1741 if we recognize that the vuse MEM operand is the same for both,
1742 and that we can skip both statements (they don't clobber us).
1743 This is still linear. Don't use maybe_skip_until, that might
1744 potentially be slow. */
1745 else if ((common_vuse = gimple_vuse (def0))
1746 && common_vuse == gimple_vuse (def1))
1748 if (!stmt_may_clobber_ref_p_1 (def0, ref)
1749 && !stmt_may_clobber_ref_p_1 (def1, ref))
1757 /* Based on the memory reference REF and its virtual use VUSE call
1758 WALKER for each virtual use that is equivalent to VUSE, including VUSE
1759 itself. That is, for each virtual use for which its defining statement
1760 does not clobber REF.
1762 WALKER is called with REF, the current virtual use and DATA. If
1763 WALKER returns non-NULL the walk stops and its result is returned.
1764 At the end of a non-successful walk NULL is returned.
1766 TRANSLATE if non-NULL is called with a pointer to REF, the virtual
1767 use which definition is a statement that may clobber REF and DATA.
1768 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
1769 If TRANSLATE returns non-NULL the walk stops and its result is returned.
1770 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
1771 to adjust REF and *DATA to make that valid.
1773 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
1776 walk_non_aliased_vuses (ao_ref *ref, tree vuse,
1777 void *(*walker)(ao_ref *, tree, void *),
1778 void *(*translate)(ao_ref *, tree, void *), void *data)
1780 bitmap visited = NULL;
1783 timevar_push (TV_ALIAS_STMT_WALK);
1789 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1790 res = (*walker) (ref, vuse, data);
1794 def_stmt = SSA_NAME_DEF_STMT (vuse);
1795 if (gimple_nop_p (def_stmt))
1797 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1798 vuse = get_continuation_for_phi (def_stmt, ref, &visited);
1801 if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
1805 res = (*translate) (ref, vuse, data);
1806 /* Failed lookup and translation. */
1807 if (res == (void *)-1)
1812 /* Lookup succeeded. */
1813 else if (res != NULL)
1815 /* Translation succeeded, continue walking. */
1817 vuse = gimple_vuse (def_stmt);
1823 BITMAP_FREE (visited);
1825 timevar_pop (TV_ALIAS_STMT_WALK);
1831 /* Based on the memory reference REF call WALKER for each vdef which
1832 defining statement may clobber REF, starting with VDEF. If REF
1833 is NULL_TREE, each defining statement is visited.
1835 WALKER is called with REF, the current vdef and DATA. If WALKER
1836 returns true the walk is stopped, otherwise it continues.
1838 At PHI nodes walk_aliased_vdefs forks into one walk for reach
1839 PHI argument (but only one walk continues on merge points), the
1840 return value is true if any of the walks was successful.
1842 The function returns the number of statements walked. */
1845 walk_aliased_vdefs_1 (ao_ref *ref, tree vdef,
1846 bool (*walker)(ao_ref *, tree, void *), void *data,
1847 bitmap *visited, unsigned int cnt)
1851 gimple def_stmt = SSA_NAME_DEF_STMT (vdef);
1854 && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef)))
1857 if (gimple_nop_p (def_stmt))
1859 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1863 *visited = BITMAP_ALLOC (NULL);
1864 for (i = 0; i < gimple_phi_num_args (def_stmt); ++i)
1865 cnt += walk_aliased_vdefs_1 (ref, gimple_phi_arg_def (def_stmt, i),
1866 walker, data, visited, 0);
1870 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1873 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1874 && (*walker) (ref, vdef, data))
1877 vdef = gimple_vuse (def_stmt);
1883 walk_aliased_vdefs (ao_ref *ref, tree vdef,
1884 bool (*walker)(ao_ref *, tree, void *), void *data,
1887 bitmap local_visited = NULL;
1890 timevar_push (TV_ALIAS_STMT_WALK);
1892 ret = walk_aliased_vdefs_1 (ref, vdef, walker, data,
1893 visited ? visited : &local_visited, 0);
1895 BITMAP_FREE (local_visited);
1897 timevar_pop (TV_ALIAS_STMT_WALK);