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,
597 alias_set_type ref1_alias_set,
598 alias_set_type base1_alias_set,
599 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
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. */
617 /* Choose bases and base types to search for. */
619 while (handled_component_p (base1))
620 base1 = TREE_OPERAND (base1, 0);
621 type1 = TREE_TYPE (base1);
623 while (handled_component_p (base2))
624 base2 = TREE_OPERAND (base2, 0);
625 type2 = TREE_TYPE (base2);
627 /* Now search for the type1 in the access path of ref2. This
628 would be a common base for doing offset based disambiguation on. */
630 while (handled_component_p (*refp)
631 && same_type_for_tbaa (TREE_TYPE (*refp), type1) == 0)
632 refp = &TREE_OPERAND (*refp, 0);
633 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type1);
634 /* If we couldn't compare types we have to bail out. */
637 else if (same_p == 1)
639 HOST_WIDE_INT offadj, sztmp, msztmp;
640 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
642 get_ref_base_and_extent (base1, &offadj, &sztmp, &msztmp);
644 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
646 /* If we didn't find a common base, try the other way around. */
648 while (handled_component_p (*refp)
649 && same_type_for_tbaa (TREE_TYPE (*refp), type2) == 0)
650 refp = &TREE_OPERAND (*refp, 0);
651 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type2);
652 /* If we couldn't compare types we have to bail out. */
655 else if (same_p == 1)
657 HOST_WIDE_INT offadj, sztmp, msztmp;
658 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
660 get_ref_base_and_extent (base2, &offadj, &sztmp, &msztmp);
662 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
665 /* If we have two type access paths B1.path1 and B2.path2 they may
666 only alias if either B1 is in B2.path2 or B2 is in B1.path1.
667 But we can still have a path that goes B1.path1...B2.path2 with
668 a part that we do not see. So we can only disambiguate now
669 if there is no B2 in the tail of path1 and no B1 on the
671 if (base1_alias_set == ref2_alias_set
672 || alias_set_subset_of (base1_alias_set, ref2_alias_set))
674 /* If this is ptr vs. decl then we know there is no ptr ... decl path. */
676 return (base2_alias_set == ref1_alias_set
677 || alias_set_subset_of (base2_alias_set, ref1_alias_set));
681 /* Return true if two memory references based on the variables BASE1
682 and BASE2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
683 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. */
686 decl_refs_may_alias_p (tree base1,
687 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
689 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
691 gcc_assert (SSA_VAR_P (base1) && SSA_VAR_P (base2));
693 /* If both references are based on different variables, they cannot alias. */
697 /* If both references are based on the same variable, they cannot alias if
698 the accesses do not overlap. */
699 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
702 /* Return true if an indirect reference based on *PTR1 constrained
703 to [OFFSET1, OFFSET1 + MAX_SIZE1) may alias a variable based on BASE2
704 constrained to [OFFSET2, OFFSET2 + MAX_SIZE2). *PTR1 and BASE2 have
705 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
706 in which case they are computed on-demand. REF1 and REF2
707 if non-NULL are the complete memory reference trees. */
710 indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
711 HOST_WIDE_INT offset1,
712 HOST_WIDE_INT max_size1 ATTRIBUTE_UNUSED,
713 alias_set_type ref1_alias_set,
714 alias_set_type base1_alias_set,
715 tree ref2 ATTRIBUTE_UNUSED, tree base2,
716 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
717 alias_set_type ref2_alias_set,
718 alias_set_type base2_alias_set, bool tbaa_p)
722 HOST_WIDE_INT offset1p = offset1, offset2p = offset2;
724 ptr1 = TREE_OPERAND (base1, 0);
726 /* The offset embedded in MEM_REFs can be negative. Bias them
727 so that the resulting offset adjustment is positive. */
728 if (TREE_CODE (base1) == MEM_REF
729 || TREE_CODE (base1) == TARGET_MEM_REF)
731 double_int moff = mem_ref_offset (base1);
732 moff = double_int_lshift (moff,
734 ? 3 : exact_log2 (BITS_PER_UNIT),
735 HOST_BITS_PER_DOUBLE_INT, true);
736 if (double_int_negative_p (moff))
737 offset2p += double_int_neg (moff).low;
739 offset1p += moff.low;
742 /* If only one reference is based on a variable, they cannot alias if
743 the pointer access is beyond the extent of the variable access.
744 (the pointer base cannot validly point to an offset less than zero
746 They also cannot alias if the pointer may not point to the decl. */
747 if ((TREE_CODE (base1) != TARGET_MEM_REF
748 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
749 && !ranges_overlap_p (MAX (0, offset1p), -1, offset2p, max_size2))
751 if (!ptr_deref_may_alias_decl_p (ptr1, base2))
754 /* Disambiguations that rely on strict aliasing rules follow. */
755 if (!flag_strict_aliasing || !tbaa_p)
758 if (TREE_CODE (base1) == MEM_REF)
759 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
760 else if (TREE_CODE (base1) == TARGET_MEM_REF)
761 ptrtype1 = TREE_TYPE (TMR_OFFSET (base1));
763 ptrtype1 = TREE_TYPE (ptr1);
765 /* If the alias set for a pointer access is zero all bets are off. */
766 if (base1_alias_set == -1)
767 base1_alias_set = get_deref_alias_set (ptrtype1);
768 if (base1_alias_set == 0)
770 if (base2_alias_set == -1)
771 base2_alias_set = get_alias_set (base2);
773 /* If both references are through the same type, they do not alias
774 if the accesses do not overlap. This does extra disambiguation
775 for mixed/pointer accesses but requires strict aliasing.
776 For MEM_REFs we require that the component-ref offset we computed
777 is relative to the start of the type which we ensure by
778 comparing rvalue and access type and disregarding the constant
780 if ((TREE_CODE (base1) != TARGET_MEM_REF
781 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
782 && (TREE_CODE (base1) != MEM_REF
783 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
784 && same_type_for_tbaa (TREE_TYPE (ptrtype1), TREE_TYPE (base2)) == 1)
785 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
787 /* When we are trying to disambiguate an access with a pointer dereference
788 as base versus one with a decl as base we can use both the size
789 of the decl and its dynamic type for extra disambiguation.
790 ??? We do not know anything about the dynamic type of the decl
791 other than that its alias-set contains base2_alias_set as a subset
792 which does not help us here. */
793 /* As we know nothing useful about the dynamic type of the decl just
794 use the usual conflict check rather than a subset test.
795 ??? We could introduce -fvery-strict-aliasing when the language
796 does not allow decls to have a dynamic type that differs from their
797 static type. Then we can check
798 !alias_set_subset_of (base1_alias_set, base2_alias_set) instead. */
799 if (base1_alias_set != base2_alias_set
800 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
802 /* If the size of the access relevant for TBAA through the pointer
803 is bigger than the size of the decl we can't possibly access the
804 decl via that pointer. */
805 if (DECL_SIZE (base2) && COMPLETE_TYPE_P (TREE_TYPE (ptrtype1))
806 && TREE_CODE (DECL_SIZE (base2)) == INTEGER_CST
807 && TREE_CODE (TYPE_SIZE (TREE_TYPE (ptrtype1))) == INTEGER_CST
808 /* ??? This in turn may run afoul when a decl of type T which is
809 a member of union type U is accessed through a pointer to
810 type U and sizeof T is smaller than sizeof U. */
811 && TREE_CODE (TREE_TYPE (ptrtype1)) != UNION_TYPE
812 && TREE_CODE (TREE_TYPE (ptrtype1)) != QUAL_UNION_TYPE
813 && tree_int_cst_lt (DECL_SIZE (base2), TYPE_SIZE (TREE_TYPE (ptrtype1))))
816 /* Do access-path based disambiguation. */
818 && handled_component_p (ref1)
819 && handled_component_p (ref2)
820 && TREE_CODE (base1) != TARGET_MEM_REF
821 && (TREE_CODE (base1) != MEM_REF
822 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1))
823 return aliasing_component_refs_p (ref1,
824 ref1_alias_set, base1_alias_set,
827 ref2_alias_set, base2_alias_set,
828 offset2, max_size2, true);
833 /* Return true if two indirect references based on *PTR1
834 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
835 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have
836 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
837 in which case they are computed on-demand. REF1 and REF2
838 if non-NULL are the complete memory reference trees. */
841 indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
842 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
843 alias_set_type ref1_alias_set,
844 alias_set_type base1_alias_set,
845 tree ref2 ATTRIBUTE_UNUSED, tree base2,
846 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
847 alias_set_type ref2_alias_set,
848 alias_set_type base2_alias_set, bool tbaa_p)
852 tree ptrtype1, ptrtype2;
854 ptr1 = TREE_OPERAND (base1, 0);
855 ptr2 = TREE_OPERAND (base2, 0);
857 /* If both bases are based on pointers they cannot alias if they may not
858 point to the same memory object or if they point to the same object
859 and the accesses do not overlap. */
860 if ((!cfun || gimple_in_ssa_p (cfun))
861 && operand_equal_p (ptr1, ptr2, 0)
862 && (((TREE_CODE (base1) != TARGET_MEM_REF
863 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
864 && (TREE_CODE (base2) != TARGET_MEM_REF
865 || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2))))
866 || (TREE_CODE (base1) == TARGET_MEM_REF
867 && TREE_CODE (base2) == TARGET_MEM_REF
868 && (TMR_STEP (base1) == TMR_STEP (base2)
869 || (TMR_STEP (base1) && TMR_STEP (base2)
870 && operand_equal_p (TMR_STEP (base1),
871 TMR_STEP (base2), 0)))
872 && (TMR_INDEX (base1) == TMR_INDEX (base2)
873 || (TMR_INDEX (base1) && TMR_INDEX (base2)
874 && operand_equal_p (TMR_INDEX (base1),
875 TMR_INDEX (base2), 0)))
876 && (TMR_INDEX2 (base1) == TMR_INDEX2 (base2)
877 || (TMR_INDEX2 (base1) && TMR_INDEX2 (base2)
878 && operand_equal_p (TMR_INDEX2 (base1),
879 TMR_INDEX2 (base2), 0))))))
881 /* The offset embedded in MEM_REFs can be negative. Bias them
882 so that the resulting offset adjustment is positive. */
883 if (TREE_CODE (base1) == MEM_REF
884 || TREE_CODE (base1) == TARGET_MEM_REF)
886 double_int moff = mem_ref_offset (base1);
887 moff = double_int_lshift (moff,
889 ? 3 : exact_log2 (BITS_PER_UNIT),
890 HOST_BITS_PER_DOUBLE_INT, true);
891 if (double_int_negative_p (moff))
892 offset2 += double_int_neg (moff).low;
896 if (TREE_CODE (base2) == MEM_REF
897 || TREE_CODE (base2) == TARGET_MEM_REF)
899 double_int moff = mem_ref_offset (base2);
900 moff = double_int_lshift (moff,
902 ? 3 : exact_log2 (BITS_PER_UNIT),
903 HOST_BITS_PER_DOUBLE_INT, true);
904 if (double_int_negative_p (moff))
905 offset1 += double_int_neg (moff).low;
909 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
911 if (!ptr_derefs_may_alias_p (ptr1, ptr2))
914 /* Disambiguations that rely on strict aliasing rules follow. */
915 if (!flag_strict_aliasing || !tbaa_p)
918 if (TREE_CODE (base1) == MEM_REF)
919 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
920 else if (TREE_CODE (base1) == TARGET_MEM_REF)
921 ptrtype1 = TREE_TYPE (TMR_OFFSET (base1));
923 ptrtype1 = TREE_TYPE (ptr1);
924 if (TREE_CODE (base2) == MEM_REF)
925 ptrtype2 = TREE_TYPE (TREE_OPERAND (base2, 1));
926 else if (TREE_CODE (base2) == TARGET_MEM_REF)
927 ptrtype2 = TREE_TYPE (TMR_OFFSET (base2));
929 ptrtype2 = TREE_TYPE (ptr2);
931 /* If the alias set for a pointer access is zero all bets are off. */
932 if (base1_alias_set == -1)
933 base1_alias_set = get_deref_alias_set (ptrtype1);
934 if (base1_alias_set == 0)
936 if (base2_alias_set == -1)
937 base2_alias_set = get_deref_alias_set (ptrtype2);
938 if (base2_alias_set == 0)
941 /* If both references are through the same type, they do not alias
942 if the accesses do not overlap. This does extra disambiguation
943 for mixed/pointer accesses but requires strict aliasing. */
944 if ((TREE_CODE (base1) != TARGET_MEM_REF || !TMR_INDEX (base1))
945 && (TREE_CODE (base2) != TARGET_MEM_REF || !TMR_INDEX (base2))
946 && (TREE_CODE (base1) != MEM_REF
947 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
948 && (TREE_CODE (base2) != MEM_REF
949 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1)
950 && same_type_for_tbaa (TREE_TYPE (ptrtype1),
951 TREE_TYPE (ptrtype2)) == 1)
952 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
954 /* Do type-based disambiguation. */
955 if (base1_alias_set != base2_alias_set
956 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
959 /* Do access-path based disambiguation. */
961 && handled_component_p (ref1)
962 && handled_component_p (ref2)
963 && TREE_CODE (base1) != TARGET_MEM_REF
964 && TREE_CODE (base2) != TARGET_MEM_REF
965 && (TREE_CODE (base1) != MEM_REF
966 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
967 && (TREE_CODE (base2) != MEM_REF
968 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1))
969 return aliasing_component_refs_p (ref1,
970 ref1_alias_set, base1_alias_set,
973 ref2_alias_set, base2_alias_set,
974 offset2, max_size2, false);
979 /* Return true, if the two memory references REF1 and REF2 may alias. */
982 refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
985 HOST_WIDE_INT offset1 = 0, offset2 = 0;
986 HOST_WIDE_INT max_size1 = -1, max_size2 = -1;
987 bool var1_p, var2_p, ind1_p, ind2_p;
989 gcc_checking_assert ((!ref1->ref
990 || TREE_CODE (ref1->ref) == SSA_NAME
991 || DECL_P (ref1->ref)
992 || TREE_CODE (ref1->ref) == STRING_CST
993 || handled_component_p (ref1->ref)
994 || INDIRECT_REF_P (ref1->ref)
995 || TREE_CODE (ref1->ref) == MEM_REF
996 || TREE_CODE (ref1->ref) == TARGET_MEM_REF)
998 || TREE_CODE (ref2->ref) == SSA_NAME
999 || DECL_P (ref2->ref)
1000 || TREE_CODE (ref2->ref) == STRING_CST
1001 || handled_component_p (ref2->ref)
1002 || INDIRECT_REF_P (ref2->ref)
1003 || TREE_CODE (ref2->ref) == MEM_REF
1004 || TREE_CODE (ref2->ref) == TARGET_MEM_REF));
1006 /* Decompose the references into their base objects and the access. */
1007 base1 = ao_ref_base (ref1);
1008 offset1 = ref1->offset;
1009 max_size1 = ref1->max_size;
1010 base2 = ao_ref_base (ref2);
1011 offset2 = ref2->offset;
1012 max_size2 = ref2->max_size;
1014 /* We can end up with registers or constants as bases for example from
1015 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
1016 which is seen as a struct copy. */
1017 if (TREE_CODE (base1) == SSA_NAME
1018 || TREE_CODE (base1) == CONST_DECL
1019 || TREE_CODE (base1) == CONSTRUCTOR
1020 || TREE_CODE (base1) == ADDR_EXPR
1021 || CONSTANT_CLASS_P (base1)
1022 || TREE_CODE (base2) == SSA_NAME
1023 || TREE_CODE (base2) == CONST_DECL
1024 || TREE_CODE (base2) == CONSTRUCTOR
1025 || TREE_CODE (base2) == ADDR_EXPR
1026 || CONSTANT_CLASS_P (base2))
1029 /* We can end up refering to code via function and label decls.
1030 As we likely do not properly track code aliases conservatively
1032 if (TREE_CODE (base1) == FUNCTION_DECL
1033 || TREE_CODE (base1) == LABEL_DECL
1034 || TREE_CODE (base2) == FUNCTION_DECL
1035 || TREE_CODE (base2) == LABEL_DECL)
1038 /* Defer to simple offset based disambiguation if we have
1039 references based on two decls. Do this before defering to
1040 TBAA to handle must-alias cases in conformance with the
1041 GCC extension of allowing type-punning through unions. */
1042 var1_p = SSA_VAR_P (base1);
1043 var2_p = SSA_VAR_P (base2);
1044 if (var1_p && var2_p)
1045 return decl_refs_may_alias_p (base1, offset1, max_size1,
1046 base2, offset2, max_size2);
1048 ind1_p = (INDIRECT_REF_P (base1)
1049 || (TREE_CODE (base1) == MEM_REF)
1050 || (TREE_CODE (base1) == TARGET_MEM_REF));
1051 ind2_p = (INDIRECT_REF_P (base2)
1052 || (TREE_CODE (base2) == MEM_REF)
1053 || (TREE_CODE (base2) == TARGET_MEM_REF));
1055 /* Canonicalize the pointer-vs-decl case. */
1056 if (ind1_p && var2_p)
1061 tmp1 = offset1; offset1 = offset2; offset2 = tmp1;
1062 tmp1 = max_size1; max_size1 = max_size2; max_size2 = tmp1;
1063 tmp2 = base1; base1 = base2; base2 = tmp2;
1064 tmp3 = ref1; ref1 = ref2; ref2 = tmp3;
1071 /* First defer to TBAA if possible. */
1073 && flag_strict_aliasing
1074 && !alias_sets_conflict_p (ao_ref_alias_set (ref1),
1075 ao_ref_alias_set (ref2)))
1078 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */
1079 if (var1_p && ind2_p)
1080 return indirect_ref_may_alias_decl_p (ref2->ref, base2,
1082 ao_ref_alias_set (ref2), -1,
1085 ao_ref_alias_set (ref1),
1086 ao_ref_base_alias_set (ref1),
1088 else if (ind1_p && ind2_p)
1089 return indirect_refs_may_alias_p (ref1->ref, base1,
1091 ao_ref_alias_set (ref1), -1,
1094 ao_ref_alias_set (ref2), -1,
1097 /* We really do not want to end up here, but returning true is safe. */
1098 #ifdef ENABLE_CHECKING
1106 refs_may_alias_p (tree ref1, tree ref2)
1110 ao_ref_init (&r1, ref1);
1111 ao_ref_init (&r2, ref2);
1112 res = refs_may_alias_p_1 (&r1, &r2, true);
1114 ++alias_stats.refs_may_alias_p_may_alias;
1116 ++alias_stats.refs_may_alias_p_no_alias;
1120 /* Returns true if there is a anti-dependence for the STORE that
1121 executes after the LOAD. */
1124 refs_anti_dependent_p (tree load, tree store)
1127 ao_ref_init (&r1, load);
1128 ao_ref_init (&r2, store);
1129 return refs_may_alias_p_1 (&r1, &r2, false);
1132 /* Returns true if there is a output dependence for the stores
1133 STORE1 and STORE2. */
1136 refs_output_dependent_p (tree store1, tree store2)
1139 ao_ref_init (&r1, store1);
1140 ao_ref_init (&r2, store2);
1141 return refs_may_alias_p_1 (&r1, &r2, false);
1144 /* If the call CALL may use the memory reference REF return true,
1145 otherwise return false. */
1148 ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
1152 int flags = gimple_call_flags (call);
1154 /* Const functions without a static chain do not implicitly use memory. */
1155 if (!gimple_call_chain (call)
1156 && (flags & (ECF_CONST|ECF_NOVOPS)))
1159 base = ao_ref_base (ref);
1163 /* If the reference is based on a decl that is not aliased the call
1164 cannot possibly use it. */
1166 && !may_be_aliased (base)
1167 /* But local statics can be used through recursion. */
1168 && !is_global_var (base))
1171 callee = gimple_call_fndecl (call);
1173 /* Handle those builtin functions explicitly that do not act as
1174 escape points. See tree-ssa-structalias.c:find_func_aliases
1175 for the list of builtins we might need to handle here. */
1176 if (callee != NULL_TREE
1177 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1178 switch (DECL_FUNCTION_CODE (callee))
1180 /* All the following functions clobber memory pointed to by
1181 their first argument. */
1182 case BUILT_IN_STRCPY:
1183 case BUILT_IN_STRNCPY:
1184 case BUILT_IN_MEMCPY:
1185 case BUILT_IN_MEMMOVE:
1186 case BUILT_IN_MEMPCPY:
1187 case BUILT_IN_STPCPY:
1188 case BUILT_IN_STPNCPY:
1189 case BUILT_IN_STRCAT:
1190 case BUILT_IN_STRNCAT:
1193 tree size = NULL_TREE;
1194 if (gimple_call_num_args (call) == 3)
1195 size = gimple_call_arg (call, 2);
1196 ao_ref_init_from_ptr_and_size (&dref,
1197 gimple_call_arg (call, 1),
1199 return refs_may_alias_p_1 (&dref, ref, false);
1201 case BUILT_IN_BCOPY:
1204 tree size = gimple_call_arg (call, 2);
1205 ao_ref_init_from_ptr_and_size (&dref,
1206 gimple_call_arg (call, 0),
1208 return refs_may_alias_p_1 (&dref, ref, false);
1210 /* The following builtins do not read from memory. */
1212 case BUILT_IN_MALLOC:
1213 case BUILT_IN_CALLOC:
1214 case BUILT_IN_ALLOCA:
1215 case BUILT_IN_STACK_SAVE:
1216 case BUILT_IN_STACK_RESTORE:
1217 case BUILT_IN_MEMSET:
1218 case BUILT_IN_FREXP:
1219 case BUILT_IN_FREXPF:
1220 case BUILT_IN_FREXPL:
1221 case BUILT_IN_GAMMA_R:
1222 case BUILT_IN_GAMMAF_R:
1223 case BUILT_IN_GAMMAL_R:
1224 case BUILT_IN_LGAMMA_R:
1225 case BUILT_IN_LGAMMAF_R:
1226 case BUILT_IN_LGAMMAL_R:
1228 case BUILT_IN_MODFF:
1229 case BUILT_IN_MODFL:
1230 case BUILT_IN_REMQUO:
1231 case BUILT_IN_REMQUOF:
1232 case BUILT_IN_REMQUOL:
1233 case BUILT_IN_SINCOS:
1234 case BUILT_IN_SINCOSF:
1235 case BUILT_IN_SINCOSL:
1237 /* __sync_* builtins and some OpenMP builtins act as threading
1239 #undef DEF_SYNC_BUILTIN
1240 #define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM:
1241 #include "sync-builtins.def"
1242 #undef DEF_SYNC_BUILTIN
1243 case BUILT_IN_GOMP_ATOMIC_START:
1244 case BUILT_IN_GOMP_ATOMIC_END:
1245 case BUILT_IN_GOMP_BARRIER:
1246 case BUILT_IN_GOMP_TASKWAIT:
1247 case BUILT_IN_GOMP_CRITICAL_START:
1248 case BUILT_IN_GOMP_CRITICAL_END:
1249 case BUILT_IN_GOMP_CRITICAL_NAME_START:
1250 case BUILT_IN_GOMP_CRITICAL_NAME_END:
1251 case BUILT_IN_GOMP_LOOP_END:
1252 case BUILT_IN_GOMP_ORDERED_START:
1253 case BUILT_IN_GOMP_ORDERED_END:
1254 case BUILT_IN_GOMP_PARALLEL_END:
1255 case BUILT_IN_GOMP_SECTIONS_END:
1256 case BUILT_IN_GOMP_SINGLE_COPY_START:
1257 case BUILT_IN_GOMP_SINGLE_COPY_END:
1261 /* Fallthru to general call handling. */;
1264 /* Check if base is a global static variable that is not read
1266 if (callee != NULL_TREE
1267 && TREE_CODE (base) == VAR_DECL
1268 && TREE_STATIC (base))
1270 struct cgraph_node *node = cgraph_get_node (callee);
1273 /* FIXME: Callee can be an OMP builtin that does not have a call graph
1274 node yet. We should enforce that there are nodes for all decls in the
1275 IL and remove this check instead. */
1277 && (not_read = ipa_reference_get_not_read_global (node))
1278 && bitmap_bit_p (not_read, DECL_UID (base)))
1282 /* Check if the base variable is call-used. */
1285 if (pt_solution_includes (gimple_call_use_set (call), base))
1288 else if ((INDIRECT_REF_P (base)
1289 || TREE_CODE (base) == MEM_REF)
1290 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1292 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1296 if (pt_solutions_intersect (gimple_call_use_set (call), &pi->pt))
1302 /* Inspect call arguments for passed-by-value aliases. */
1304 for (i = 0; i < gimple_call_num_args (call); ++i)
1306 tree op = gimple_call_arg (call, i);
1307 int flags = gimple_call_arg_flags (call, i);
1309 if (flags & EAF_UNUSED)
1312 if (TREE_CODE (op) == WITH_SIZE_EXPR)
1313 op = TREE_OPERAND (op, 0);
1315 if (TREE_CODE (op) != SSA_NAME
1316 && !is_gimple_min_invariant (op))
1319 ao_ref_init (&r, op);
1320 if (refs_may_alias_p_1 (&r, ref, true))
1329 ref_maybe_used_by_call_p (gimple call, tree ref)
1333 ao_ref_init (&r, ref);
1334 res = ref_maybe_used_by_call_p_1 (call, &r);
1336 ++alias_stats.ref_maybe_used_by_call_p_may_alias;
1338 ++alias_stats.ref_maybe_used_by_call_p_no_alias;
1343 /* If the statement STMT may use the memory reference REF return
1344 true, otherwise return false. */
1347 ref_maybe_used_by_stmt_p (gimple stmt, tree ref)
1349 if (is_gimple_assign (stmt))
1353 /* All memory assign statements are single. */
1354 if (!gimple_assign_single_p (stmt))
1357 rhs = gimple_assign_rhs1 (stmt);
1358 if (is_gimple_reg (rhs)
1359 || is_gimple_min_invariant (rhs)
1360 || gimple_assign_rhs_code (stmt) == CONSTRUCTOR)
1363 return refs_may_alias_p (rhs, ref);
1365 else if (is_gimple_call (stmt))
1366 return ref_maybe_used_by_call_p (stmt, ref);
1367 else if (gimple_code (stmt) == GIMPLE_RETURN)
1369 tree retval = gimple_return_retval (stmt);
1372 && TREE_CODE (retval) != SSA_NAME
1373 && !is_gimple_min_invariant (retval)
1374 && refs_may_alias_p (retval, ref))
1376 /* If ref escapes the function then the return acts as a use. */
1377 base = get_base_address (ref);
1380 else if (DECL_P (base))
1381 return is_global_var (base);
1382 else if (TREE_CODE (base) == MEM_REF
1383 || TREE_CODE (base) == TARGET_MEM_REF)
1384 return ptr_deref_may_alias_global_p (TREE_OPERAND (base, 0));
1391 /* If the call in statement CALL may clobber the memory reference REF
1392 return true, otherwise return false. */
1395 call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
1400 /* If the call is pure or const it cannot clobber anything. */
1401 if (gimple_call_flags (call)
1402 & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS))
1405 base = ao_ref_base (ref);
1409 if (TREE_CODE (base) == SSA_NAME
1410 || CONSTANT_CLASS_P (base))
1413 /* If the reference is based on a decl that is not aliased the call
1414 cannot possibly clobber it. */
1416 && !may_be_aliased (base)
1417 /* But local non-readonly statics can be modified through recursion
1418 or the call may implement a threading barrier which we must
1419 treat as may-def. */
1420 && (TREE_READONLY (base)
1421 || !is_global_var (base)))
1424 callee = gimple_call_fndecl (call);
1426 /* Handle those builtin functions explicitly that do not act as
1427 escape points. See tree-ssa-structalias.c:find_func_aliases
1428 for the list of builtins we might need to handle here. */
1429 if (callee != NULL_TREE
1430 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1431 switch (DECL_FUNCTION_CODE (callee))
1433 /* All the following functions clobber memory pointed to by
1434 their first argument. */
1435 case BUILT_IN_STRCPY:
1436 case BUILT_IN_STRNCPY:
1437 case BUILT_IN_MEMCPY:
1438 case BUILT_IN_MEMMOVE:
1439 case BUILT_IN_MEMPCPY:
1440 case BUILT_IN_STPCPY:
1441 case BUILT_IN_STPNCPY:
1442 case BUILT_IN_STRCAT:
1443 case BUILT_IN_STRNCAT:
1444 case BUILT_IN_MEMSET:
1447 tree size = NULL_TREE;
1448 if (gimple_call_num_args (call) == 3)
1449 size = gimple_call_arg (call, 2);
1450 ao_ref_init_from_ptr_and_size (&dref,
1451 gimple_call_arg (call, 0),
1453 return refs_may_alias_p_1 (&dref, ref, false);
1455 case BUILT_IN_BCOPY:
1458 tree size = gimple_call_arg (call, 2);
1459 ao_ref_init_from_ptr_and_size (&dref,
1460 gimple_call_arg (call, 1),
1462 return refs_may_alias_p_1 (&dref, ref, false);
1464 /* Allocating memory does not have any side-effects apart from
1465 being the definition point for the pointer. */
1466 case BUILT_IN_MALLOC:
1467 case BUILT_IN_CALLOC:
1468 /* Unix98 specifies that errno is set on allocation failure. */
1470 && targetm.ref_may_alias_errno (ref))
1473 case BUILT_IN_STACK_SAVE:
1474 case BUILT_IN_ALLOCA:
1476 /* Freeing memory kills the pointed-to memory. More importantly
1477 the call has to serve as a barrier for moving loads and stores
1481 tree ptr = gimple_call_arg (call, 0);
1482 return ptr_deref_may_alias_ref_p_1 (ptr, ref);
1484 case BUILT_IN_GAMMA_R:
1485 case BUILT_IN_GAMMAF_R:
1486 case BUILT_IN_GAMMAL_R:
1487 case BUILT_IN_LGAMMA_R:
1488 case BUILT_IN_LGAMMAF_R:
1489 case BUILT_IN_LGAMMAL_R:
1491 tree out = gimple_call_arg (call, 1);
1492 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1494 if (flag_errno_math)
1498 case BUILT_IN_FREXP:
1499 case BUILT_IN_FREXPF:
1500 case BUILT_IN_FREXPL:
1502 case BUILT_IN_MODFF:
1503 case BUILT_IN_MODFL:
1505 tree out = gimple_call_arg (call, 1);
1506 return ptr_deref_may_alias_ref_p_1 (out, ref);
1508 case BUILT_IN_REMQUO:
1509 case BUILT_IN_REMQUOF:
1510 case BUILT_IN_REMQUOL:
1512 tree out = gimple_call_arg (call, 2);
1513 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1515 if (flag_errno_math)
1519 case BUILT_IN_SINCOS:
1520 case BUILT_IN_SINCOSF:
1521 case BUILT_IN_SINCOSL:
1523 tree sin = gimple_call_arg (call, 1);
1524 tree cos = gimple_call_arg (call, 2);
1525 return (ptr_deref_may_alias_ref_p_1 (sin, ref)
1526 || ptr_deref_may_alias_ref_p_1 (cos, ref));
1528 /* __sync_* builtins and some OpenMP builtins act as threading
1530 #undef DEF_SYNC_BUILTIN
1531 #define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM:
1532 #include "sync-builtins.def"
1533 #undef DEF_SYNC_BUILTIN
1534 case BUILT_IN_GOMP_ATOMIC_START:
1535 case BUILT_IN_GOMP_ATOMIC_END:
1536 case BUILT_IN_GOMP_BARRIER:
1537 case BUILT_IN_GOMP_TASKWAIT:
1538 case BUILT_IN_GOMP_CRITICAL_START:
1539 case BUILT_IN_GOMP_CRITICAL_END:
1540 case BUILT_IN_GOMP_CRITICAL_NAME_START:
1541 case BUILT_IN_GOMP_CRITICAL_NAME_END:
1542 case BUILT_IN_GOMP_LOOP_END:
1543 case BUILT_IN_GOMP_ORDERED_START:
1544 case BUILT_IN_GOMP_ORDERED_END:
1545 case BUILT_IN_GOMP_PARALLEL_END:
1546 case BUILT_IN_GOMP_SECTIONS_END:
1547 case BUILT_IN_GOMP_SINGLE_COPY_START:
1548 case BUILT_IN_GOMP_SINGLE_COPY_END:
1551 /* Fallthru to general call handling. */;
1554 /* Check if base is a global static variable that is not written
1556 if (callee != NULL_TREE
1557 && TREE_CODE (base) == VAR_DECL
1558 && TREE_STATIC (base))
1560 struct cgraph_node *node = cgraph_get_node (callee);
1564 && (not_written = ipa_reference_get_not_written_global (node))
1565 && bitmap_bit_p (not_written, DECL_UID (base)))
1569 /* Check if the base variable is call-clobbered. */
1571 return pt_solution_includes (gimple_call_clobber_set (call), base);
1572 else if ((INDIRECT_REF_P (base)
1573 || TREE_CODE (base) == MEM_REF)
1574 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1576 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1580 return pt_solutions_intersect (gimple_call_clobber_set (call), &pi->pt);
1586 /* If the call in statement CALL may clobber the memory reference REF
1587 return true, otherwise return false. */
1590 call_may_clobber_ref_p (gimple call, tree ref)
1594 ao_ref_init (&r, ref);
1595 res = call_may_clobber_ref_p_1 (call, &r);
1597 ++alias_stats.call_may_clobber_ref_p_may_alias;
1599 ++alias_stats.call_may_clobber_ref_p_no_alias;
1604 /* If the statement STMT may clobber the memory reference REF return true,
1605 otherwise return false. */
1608 stmt_may_clobber_ref_p_1 (gimple stmt, ao_ref *ref)
1610 if (is_gimple_call (stmt))
1612 tree lhs = gimple_call_lhs (stmt);
1614 && TREE_CODE (lhs) != SSA_NAME)
1617 ao_ref_init (&r, lhs);
1618 if (refs_may_alias_p_1 (ref, &r, true))
1622 return call_may_clobber_ref_p_1 (stmt, ref);
1624 else if (gimple_assign_single_p (stmt))
1626 tree lhs = gimple_assign_lhs (stmt);
1627 if (TREE_CODE (lhs) != SSA_NAME)
1630 ao_ref_init (&r, lhs);
1631 return refs_may_alias_p_1 (ref, &r, true);
1634 else if (gimple_code (stmt) == GIMPLE_ASM)
1641 stmt_may_clobber_ref_p (gimple stmt, tree ref)
1644 ao_ref_init (&r, ref);
1645 return stmt_may_clobber_ref_p_1 (stmt, &r);
1648 /* If STMT kills the memory reference REF return true, otherwise
1652 stmt_kills_ref_p_1 (gimple stmt, ao_ref *ref)
1654 /* For a must-alias check we need to be able to constrain
1655 the access properly. */
1657 if (ref->max_size == -1)
1660 if (gimple_has_lhs (stmt)
1661 && TREE_CODE (gimple_get_lhs (stmt)) != SSA_NAME)
1663 tree base, lhs = gimple_get_lhs (stmt);
1664 HOST_WIDE_INT size, offset, max_size;
1665 base = get_ref_base_and_extent (lhs, &offset, &size, &max_size);
1666 /* We can get MEM[symbol: sZ, index: D.8862_1] here,
1667 so base == ref->base does not always hold. */
1668 if (base == ref->base)
1670 /* For a must-alias check we need to be able to constrain
1671 the access properly. */
1672 if (size != -1 && size == max_size)
1674 if (offset <= ref->offset
1675 && offset + size >= ref->offset + ref->max_size)
1681 if (is_gimple_call (stmt))
1683 tree callee = gimple_call_fndecl (stmt);
1684 if (callee != NULL_TREE
1685 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1686 switch (DECL_FUNCTION_CODE (callee))
1688 case BUILT_IN_MEMCPY:
1689 case BUILT_IN_MEMPCPY:
1690 case BUILT_IN_MEMMOVE:
1691 case BUILT_IN_MEMSET:
1693 tree dest = gimple_call_arg (stmt, 0);
1694 tree len = gimple_call_arg (stmt, 2);
1695 tree base = NULL_TREE;
1696 HOST_WIDE_INT offset = 0;
1697 if (!host_integerp (len, 0))
1699 if (TREE_CODE (dest) == ADDR_EXPR)
1700 base = get_addr_base_and_unit_offset (TREE_OPERAND (dest, 0),
1702 else if (TREE_CODE (dest) == SSA_NAME)
1705 && base == ao_ref_base (ref))
1707 HOST_WIDE_INT size = TREE_INT_CST_LOW (len);
1708 if (offset <= ref->offset / BITS_PER_UNIT
1710 >= ((ref->offset + ref->max_size + BITS_PER_UNIT - 1)
1723 stmt_kills_ref_p (gimple stmt, tree ref)
1726 ao_ref_init (&r, ref);
1727 return stmt_kills_ref_p_1 (stmt, &r);
1731 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand
1732 TARGET or a statement clobbering the memory reference REF in which
1733 case false is returned. The walk starts with VUSE, one argument of PHI. */
1736 maybe_skip_until (gimple phi, tree target, ao_ref *ref,
1737 tree vuse, bitmap *visited)
1740 *visited = BITMAP_ALLOC (NULL);
1742 bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi)));
1744 /* Walk until we hit the target. */
1745 while (vuse != target)
1747 gimple def_stmt = SSA_NAME_DEF_STMT (vuse);
1748 /* Recurse for PHI nodes. */
1749 if (gimple_code (def_stmt) == GIMPLE_PHI)
1751 /* An already visited PHI node ends the walk successfully. */
1752 if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt))))
1754 vuse = get_continuation_for_phi (def_stmt, ref, visited);
1759 /* A clobbering statement or the end of the IL ends it failing. */
1760 else if (gimple_nop_p (def_stmt)
1761 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1763 vuse = gimple_vuse (def_stmt);
1768 /* Starting from a PHI node for the virtual operand of the memory reference
1769 REF find a continuation virtual operand that allows to continue walking
1770 statements dominating PHI skipping only statements that cannot possibly
1771 clobber REF. Returns NULL_TREE if no suitable virtual operand can
1775 get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited)
1777 unsigned nargs = gimple_phi_num_args (phi);
1779 /* Through a single-argument PHI we can simply look through. */
1781 return PHI_ARG_DEF (phi, 0);
1783 /* For two arguments try to skip non-aliasing code until we hit
1784 the phi argument definition that dominates the other one. */
1787 tree arg0 = PHI_ARG_DEF (phi, 0);
1788 tree arg1 = PHI_ARG_DEF (phi, 1);
1789 gimple def0 = SSA_NAME_DEF_STMT (arg0);
1790 gimple def1 = SSA_NAME_DEF_STMT (arg1);
1795 else if (gimple_nop_p (def0)
1796 || (!gimple_nop_p (def1)
1797 && dominated_by_p (CDI_DOMINATORS,
1798 gimple_bb (def1), gimple_bb (def0))))
1800 if (maybe_skip_until (phi, arg0, ref, arg1, visited))
1803 else if (gimple_nop_p (def1)
1804 || dominated_by_p (CDI_DOMINATORS,
1805 gimple_bb (def0), gimple_bb (def1)))
1807 if (maybe_skip_until (phi, arg1, ref, arg0, visited))
1810 /* Special case of a diamond:
1812 goto (cond) ? L1 : L2
1813 L1: store1 = ... #MEM_2 = vuse(MEM_1)
1815 L2: store2 = ... #MEM_3 = vuse(MEM_1)
1816 L3: MEM_4 = PHI<MEM_2, MEM_3>
1817 We were called with the PHI at L3, MEM_2 and MEM_3 don't
1818 dominate each other, but still we can easily skip this PHI node
1819 if we recognize that the vuse MEM operand is the same for both,
1820 and that we can skip both statements (they don't clobber us).
1821 This is still linear. Don't use maybe_skip_until, that might
1822 potentially be slow. */
1823 else if ((common_vuse = gimple_vuse (def0))
1824 && common_vuse == gimple_vuse (def1))
1826 if (!stmt_may_clobber_ref_p_1 (def0, ref)
1827 && !stmt_may_clobber_ref_p_1 (def1, ref))
1835 /* Based on the memory reference REF and its virtual use VUSE call
1836 WALKER for each virtual use that is equivalent to VUSE, including VUSE
1837 itself. That is, for each virtual use for which its defining statement
1838 does not clobber REF.
1840 WALKER is called with REF, the current virtual use and DATA. If
1841 WALKER returns non-NULL the walk stops and its result is returned.
1842 At the end of a non-successful walk NULL is returned.
1844 TRANSLATE if non-NULL is called with a pointer to REF, the virtual
1845 use which definition is a statement that may clobber REF and DATA.
1846 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
1847 If TRANSLATE returns non-NULL the walk stops and its result is returned.
1848 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
1849 to adjust REF and *DATA to make that valid.
1851 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
1854 walk_non_aliased_vuses (ao_ref *ref, tree vuse,
1855 void *(*walker)(ao_ref *, tree, void *),
1856 void *(*translate)(ao_ref *, tree, void *), void *data)
1858 bitmap visited = NULL;
1861 timevar_push (TV_ALIAS_STMT_WALK);
1867 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1868 res = (*walker) (ref, vuse, data);
1872 def_stmt = SSA_NAME_DEF_STMT (vuse);
1873 if (gimple_nop_p (def_stmt))
1875 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1876 vuse = get_continuation_for_phi (def_stmt, ref, &visited);
1879 if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
1883 res = (*translate) (ref, vuse, data);
1884 /* Failed lookup and translation. */
1885 if (res == (void *)-1)
1890 /* Lookup succeeded. */
1891 else if (res != NULL)
1893 /* Translation succeeded, continue walking. */
1895 vuse = gimple_vuse (def_stmt);
1901 BITMAP_FREE (visited);
1903 timevar_pop (TV_ALIAS_STMT_WALK);
1909 /* Based on the memory reference REF call WALKER for each vdef which
1910 defining statement may clobber REF, starting with VDEF. If REF
1911 is NULL_TREE, each defining statement is visited.
1913 WALKER is called with REF, the current vdef and DATA. If WALKER
1914 returns true the walk is stopped, otherwise it continues.
1916 At PHI nodes walk_aliased_vdefs forks into one walk for reach
1917 PHI argument (but only one walk continues on merge points), the
1918 return value is true if any of the walks was successful.
1920 The function returns the number of statements walked. */
1923 walk_aliased_vdefs_1 (ao_ref *ref, tree vdef,
1924 bool (*walker)(ao_ref *, tree, void *), void *data,
1925 bitmap *visited, unsigned int cnt)
1929 gimple def_stmt = SSA_NAME_DEF_STMT (vdef);
1932 && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef)))
1935 if (gimple_nop_p (def_stmt))
1937 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1941 *visited = BITMAP_ALLOC (NULL);
1942 for (i = 0; i < gimple_phi_num_args (def_stmt); ++i)
1943 cnt += walk_aliased_vdefs_1 (ref, gimple_phi_arg_def (def_stmt, i),
1944 walker, data, visited, 0);
1948 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1951 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1952 && (*walker) (ref, vdef, data))
1955 vdef = gimple_vuse (def_stmt);
1961 walk_aliased_vdefs (ao_ref *ref, tree vdef,
1962 bool (*walker)(ao_ref *, tree, void *), void *data,
1965 bitmap local_visited = NULL;
1968 timevar_push (TV_ALIAS_STMT_WALK);
1970 ret = walk_aliased_vdefs_1 (ref, vdef, walker, data,
1971 visited ? visited : &local_visited, 0);
1973 BITMAP_FREE (local_visited);
1975 timevar_pop (TV_ALIAS_STMT_WALK);