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 && (TREE_CODE (base) == MEM_REF
200 || TREE_CODE (base) == TARGET_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 && (TREE_CODE (base) == MEM_REF
285 || TREE_CODE (base) == TARGET_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 && (TREE_CODE (base) == MEM_REF
298 || TREE_CODE (base) == TARGET_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 (TREE_CODE (base) == MEM_REF
342 || TREE_CODE (base) == TARGET_MEM_REF)
343 return ptr_derefs_may_alias_p (ptr, TREE_OPERAND (base, 0));
344 else if (DECL_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_checking_assert (DECL_P (base1) && DECL_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)
721 tree ptrtype1, dbase2;
722 HOST_WIDE_INT offset1p = offset1, offset2p = offset2;
723 HOST_WIDE_INT doffset1, doffset2;
726 gcc_checking_assert ((TREE_CODE (base1) == MEM_REF
727 || TREE_CODE (base1) == TARGET_MEM_REF)
730 ptr1 = TREE_OPERAND (base1, 0);
732 /* The offset embedded in MEM_REFs can be negative. Bias them
733 so that the resulting offset adjustment is positive. */
734 moff = mem_ref_offset (base1);
735 moff = double_int_lshift (moff,
737 ? 3 : exact_log2 (BITS_PER_UNIT),
738 HOST_BITS_PER_DOUBLE_INT, true);
739 if (double_int_negative_p (moff))
740 offset2p += double_int_neg (moff).low;
742 offset1p += moff.low;
744 /* If only one reference is based on a variable, they cannot alias if
745 the pointer access is beyond the extent of the variable access.
746 (the pointer base cannot validly point to an offset less than zero
748 They also cannot alias if the pointer may not point to the decl. */
749 if ((TREE_CODE (base1) != TARGET_MEM_REF
750 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
751 && !ranges_overlap_p (MAX (0, offset1p), -1, offset2p, max_size2))
753 if (!ptr_deref_may_alias_decl_p (ptr1, base2))
756 /* Disambiguations that rely on strict aliasing rules follow. */
757 if (!flag_strict_aliasing || !tbaa_p)
760 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
762 /* If the alias set for a pointer access is zero all bets are off. */
763 if (base1_alias_set == -1)
764 base1_alias_set = get_deref_alias_set (ptrtype1);
765 if (base1_alias_set == 0)
767 if (base2_alias_set == -1)
768 base2_alias_set = get_alias_set (base2);
770 /* When we are trying to disambiguate an access with a pointer dereference
771 as base versus one with a decl as base we can use both the size
772 of the decl and its dynamic type for extra disambiguation.
773 ??? We do not know anything about the dynamic type of the decl
774 other than that its alias-set contains base2_alias_set as a subset
775 which does not help us here. */
776 /* As we know nothing useful about the dynamic type of the decl just
777 use the usual conflict check rather than a subset test.
778 ??? We could introduce -fvery-strict-aliasing when the language
779 does not allow decls to have a dynamic type that differs from their
780 static type. Then we can check
781 !alias_set_subset_of (base1_alias_set, base2_alias_set) instead. */
782 if (base1_alias_set != base2_alias_set
783 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
785 /* If the size of the access relevant for TBAA through the pointer
786 is bigger than the size of the decl we can't possibly access the
787 decl via that pointer. */
788 if (DECL_SIZE (base2) && COMPLETE_TYPE_P (TREE_TYPE (ptrtype1))
789 && TREE_CODE (DECL_SIZE (base2)) == INTEGER_CST
790 && TREE_CODE (TYPE_SIZE (TREE_TYPE (ptrtype1))) == INTEGER_CST
791 /* ??? This in turn may run afoul when a decl of type T which is
792 a member of union type U is accessed through a pointer to
793 type U and sizeof T is smaller than sizeof U. */
794 && TREE_CODE (TREE_TYPE (ptrtype1)) != UNION_TYPE
795 && TREE_CODE (TREE_TYPE (ptrtype1)) != QUAL_UNION_TYPE
796 && tree_int_cst_lt (DECL_SIZE (base2), TYPE_SIZE (TREE_TYPE (ptrtype1))))
802 /* If the decl is accressed via a MEM_REF, reconstruct the base
803 we can use for TBAA and an appropriately adjusted offset. */
805 while (handled_component_p (dbase2))
806 dbase2 = TREE_OPERAND (dbase2, 0);
809 if (TREE_CODE (dbase2) == MEM_REF
810 || TREE_CODE (dbase2) == TARGET_MEM_REF)
812 double_int moff = mem_ref_offset (dbase2);
813 moff = double_int_lshift (moff,
815 ? 3 : exact_log2 (BITS_PER_UNIT),
816 HOST_BITS_PER_DOUBLE_INT, true);
817 if (double_int_negative_p (moff))
818 doffset1 -= double_int_neg (moff).low;
820 doffset2 -= moff.low;
823 /* If either reference is view-converted, give up now. */
824 if (same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) != 1
825 || same_type_for_tbaa (TREE_TYPE (dbase2),
826 TREE_TYPE (reference_alias_ptr_type (dbase2))) != 1)
829 /* If both references are through the same type, they do not alias
830 if the accesses do not overlap. This does extra disambiguation
831 for mixed/pointer accesses but requires strict aliasing.
832 For MEM_REFs we require that the component-ref offset we computed
833 is relative to the start of the type which we ensure by
834 comparing rvalue and access type and disregarding the constant
836 if ((TREE_CODE (base1) != TARGET_MEM_REF
837 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
838 && same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (dbase2)) == 1)
839 return ranges_overlap_p (doffset1, max_size1, doffset2, max_size2);
841 /* Do access-path based disambiguation. */
843 && (handled_component_p (ref1) || handled_component_p (ref2)))
844 return aliasing_component_refs_p (ref1,
845 ref1_alias_set, base1_alias_set,
848 ref2_alias_set, base2_alias_set,
849 offset2, max_size2, true);
854 /* Return true if two indirect references based on *PTR1
855 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
856 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have
857 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
858 in which case they are computed on-demand. REF1 and REF2
859 if non-NULL are the complete memory reference trees. */
862 indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
863 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
864 alias_set_type ref1_alias_set,
865 alias_set_type base1_alias_set,
866 tree ref2 ATTRIBUTE_UNUSED, tree base2,
867 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
868 alias_set_type ref2_alias_set,
869 alias_set_type base2_alias_set, bool tbaa_p)
873 tree ptrtype1, ptrtype2;
875 gcc_checking_assert ((TREE_CODE (base1) == MEM_REF
876 || TREE_CODE (base1) == TARGET_MEM_REF)
877 && (TREE_CODE (base2) == MEM_REF
878 || TREE_CODE (base2) == TARGET_MEM_REF));
880 ptr1 = TREE_OPERAND (base1, 0);
881 ptr2 = TREE_OPERAND (base2, 0);
883 /* If both bases are based on pointers they cannot alias if they may not
884 point to the same memory object or if they point to the same object
885 and the accesses do not overlap. */
886 if ((!cfun || gimple_in_ssa_p (cfun))
887 && operand_equal_p (ptr1, ptr2, 0)
888 && (((TREE_CODE (base1) != TARGET_MEM_REF
889 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
890 && (TREE_CODE (base2) != TARGET_MEM_REF
891 || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2))))
892 || (TREE_CODE (base1) == TARGET_MEM_REF
893 && TREE_CODE (base2) == TARGET_MEM_REF
894 && (TMR_STEP (base1) == TMR_STEP (base2)
895 || (TMR_STEP (base1) && TMR_STEP (base2)
896 && operand_equal_p (TMR_STEP (base1),
897 TMR_STEP (base2), 0)))
898 && (TMR_INDEX (base1) == TMR_INDEX (base2)
899 || (TMR_INDEX (base1) && TMR_INDEX (base2)
900 && operand_equal_p (TMR_INDEX (base1),
901 TMR_INDEX (base2), 0)))
902 && (TMR_INDEX2 (base1) == TMR_INDEX2 (base2)
903 || (TMR_INDEX2 (base1) && TMR_INDEX2 (base2)
904 && operand_equal_p (TMR_INDEX2 (base1),
905 TMR_INDEX2 (base2), 0))))))
908 /* The offset embedded in MEM_REFs can be negative. Bias them
909 so that the resulting offset adjustment is positive. */
910 moff = mem_ref_offset (base1);
911 moff = double_int_lshift (moff,
913 ? 3 : exact_log2 (BITS_PER_UNIT),
914 HOST_BITS_PER_DOUBLE_INT, true);
915 if (double_int_negative_p (moff))
916 offset2 += double_int_neg (moff).low;
919 moff = mem_ref_offset (base2);
920 moff = double_int_lshift (moff,
922 ? 3 : exact_log2 (BITS_PER_UNIT),
923 HOST_BITS_PER_DOUBLE_INT, true);
924 if (double_int_negative_p (moff))
925 offset1 += double_int_neg (moff).low;
928 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
930 if (!ptr_derefs_may_alias_p (ptr1, ptr2))
933 /* Disambiguations that rely on strict aliasing rules follow. */
934 if (!flag_strict_aliasing || !tbaa_p)
937 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
938 ptrtype2 = TREE_TYPE (TREE_OPERAND (base2, 1));
940 /* If the alias set for a pointer access is zero all bets are off. */
941 if (base1_alias_set == -1)
942 base1_alias_set = get_deref_alias_set (ptrtype1);
943 if (base1_alias_set == 0)
945 if (base2_alias_set == -1)
946 base2_alias_set = get_deref_alias_set (ptrtype2);
947 if (base2_alias_set == 0)
950 /* If both references are through the same type, they do not alias
951 if the accesses do not overlap. This does extra disambiguation
952 for mixed/pointer accesses but requires strict aliasing. */
953 if ((TREE_CODE (base1) != TARGET_MEM_REF
954 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
955 && (TREE_CODE (base2) != TARGET_MEM_REF
956 || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2)))
957 && same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1
958 && same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1
959 && same_type_for_tbaa (TREE_TYPE (ptrtype1),
960 TREE_TYPE (ptrtype2)) == 1)
961 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
963 /* Do type-based disambiguation. */
964 if (base1_alias_set != base2_alias_set
965 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
968 /* Do access-path based disambiguation. */
970 && (handled_component_p (ref1) || handled_component_p (ref2))
971 && same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1
972 && same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1)
973 return aliasing_component_refs_p (ref1,
974 ref1_alias_set, base1_alias_set,
977 ref2_alias_set, base2_alias_set,
978 offset2, max_size2, false);
983 /* Return true, if the two memory references REF1 and REF2 may alias. */
986 refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
989 HOST_WIDE_INT offset1 = 0, offset2 = 0;
990 HOST_WIDE_INT max_size1 = -1, max_size2 = -1;
991 bool var1_p, var2_p, ind1_p, ind2_p;
993 gcc_checking_assert ((!ref1->ref
994 || TREE_CODE (ref1->ref) == SSA_NAME
995 || DECL_P (ref1->ref)
996 || TREE_CODE (ref1->ref) == STRING_CST
997 || handled_component_p (ref1->ref)
998 || TREE_CODE (ref1->ref) == MEM_REF
999 || TREE_CODE (ref1->ref) == TARGET_MEM_REF)
1001 || TREE_CODE (ref2->ref) == SSA_NAME
1002 || DECL_P (ref2->ref)
1003 || TREE_CODE (ref2->ref) == STRING_CST
1004 || handled_component_p (ref2->ref)
1005 || TREE_CODE (ref2->ref) == MEM_REF
1006 || TREE_CODE (ref2->ref) == TARGET_MEM_REF));
1008 /* Decompose the references into their base objects and the access. */
1009 base1 = ao_ref_base (ref1);
1010 offset1 = ref1->offset;
1011 max_size1 = ref1->max_size;
1012 base2 = ao_ref_base (ref2);
1013 offset2 = ref2->offset;
1014 max_size2 = ref2->max_size;
1016 /* We can end up with registers or constants as bases for example from
1017 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
1018 which is seen as a struct copy. */
1019 if (TREE_CODE (base1) == SSA_NAME
1020 || TREE_CODE (base1) == CONST_DECL
1021 || TREE_CODE (base1) == CONSTRUCTOR
1022 || TREE_CODE (base1) == ADDR_EXPR
1023 || CONSTANT_CLASS_P (base1)
1024 || TREE_CODE (base2) == SSA_NAME
1025 || TREE_CODE (base2) == CONST_DECL
1026 || TREE_CODE (base2) == CONSTRUCTOR
1027 || TREE_CODE (base2) == ADDR_EXPR
1028 || CONSTANT_CLASS_P (base2))
1031 /* We can end up refering to code via function and label decls.
1032 As we likely do not properly track code aliases conservatively
1034 if (TREE_CODE (base1) == FUNCTION_DECL
1035 || TREE_CODE (base1) == LABEL_DECL
1036 || TREE_CODE (base2) == FUNCTION_DECL
1037 || TREE_CODE (base2) == LABEL_DECL)
1040 /* Defer to simple offset based disambiguation if we have
1041 references based on two decls. Do this before defering to
1042 TBAA to handle must-alias cases in conformance with the
1043 GCC extension of allowing type-punning through unions. */
1044 var1_p = DECL_P (base1);
1045 var2_p = DECL_P (base2);
1046 if (var1_p && var2_p)
1047 return decl_refs_may_alias_p (base1, offset1, max_size1,
1048 base2, offset2, max_size2);
1050 ind1_p = (TREE_CODE (base1) == MEM_REF
1051 || TREE_CODE (base1) == TARGET_MEM_REF);
1052 ind2_p = (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 ((TREE_CODE (base) == MEM_REF
1289 || TREE_CODE (base) == TARGET_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 ((TREE_CODE (base) == MEM_REF
1573 || TREE_CODE (base) == TARGET_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
1662 /* The assignment is not necessarily carried out if it can throw
1663 and we can catch it in the current function where we could inspect
1665 ??? We only need to care about the RHS throwing. For aggregate
1666 assignments or similar calls and non-call exceptions the LHS
1667 might throw as well. */
1668 && !stmt_can_throw_internal (stmt))
1670 tree base, lhs = gimple_get_lhs (stmt);
1671 HOST_WIDE_INT size, offset, max_size;
1672 base = get_ref_base_and_extent (lhs, &offset, &size, &max_size);
1673 /* We can get MEM[symbol: sZ, index: D.8862_1] here,
1674 so base == ref->base does not always hold. */
1675 if (base == ref->base)
1677 /* For a must-alias check we need to be able to constrain
1678 the access properly. */
1679 if (size != -1 && size == max_size)
1681 if (offset <= ref->offset
1682 && offset + size >= ref->offset + ref->max_size)
1688 if (is_gimple_call (stmt))
1690 tree callee = gimple_call_fndecl (stmt);
1691 if (callee != NULL_TREE
1692 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1693 switch (DECL_FUNCTION_CODE (callee))
1695 case BUILT_IN_MEMCPY:
1696 case BUILT_IN_MEMPCPY:
1697 case BUILT_IN_MEMMOVE:
1698 case BUILT_IN_MEMSET:
1700 tree dest = gimple_call_arg (stmt, 0);
1701 tree len = gimple_call_arg (stmt, 2);
1702 tree base = NULL_TREE;
1703 HOST_WIDE_INT offset = 0;
1704 if (!host_integerp (len, 0))
1706 if (TREE_CODE (dest) == ADDR_EXPR)
1707 base = get_addr_base_and_unit_offset (TREE_OPERAND (dest, 0),
1709 else if (TREE_CODE (dest) == SSA_NAME)
1712 && base == ao_ref_base (ref))
1714 HOST_WIDE_INT size = TREE_INT_CST_LOW (len);
1715 if (offset <= ref->offset / BITS_PER_UNIT
1717 >= ((ref->offset + ref->max_size + BITS_PER_UNIT - 1)
1730 stmt_kills_ref_p (gimple stmt, tree ref)
1733 ao_ref_init (&r, ref);
1734 return stmt_kills_ref_p_1 (stmt, &r);
1738 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand
1739 TARGET or a statement clobbering the memory reference REF in which
1740 case false is returned. The walk starts with VUSE, one argument of PHI. */
1743 maybe_skip_until (gimple phi, tree target, ao_ref *ref,
1744 tree vuse, bitmap *visited)
1747 *visited = BITMAP_ALLOC (NULL);
1749 bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi)));
1751 /* Walk until we hit the target. */
1752 while (vuse != target)
1754 gimple def_stmt = SSA_NAME_DEF_STMT (vuse);
1755 /* Recurse for PHI nodes. */
1756 if (gimple_code (def_stmt) == GIMPLE_PHI)
1758 /* An already visited PHI node ends the walk successfully. */
1759 if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt))))
1761 vuse = get_continuation_for_phi (def_stmt, ref, visited);
1766 /* A clobbering statement or the end of the IL ends it failing. */
1767 else if (gimple_nop_p (def_stmt)
1768 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1770 vuse = gimple_vuse (def_stmt);
1775 /* Starting from a PHI node for the virtual operand of the memory reference
1776 REF find a continuation virtual operand that allows to continue walking
1777 statements dominating PHI skipping only statements that cannot possibly
1778 clobber REF. Returns NULL_TREE if no suitable virtual operand can
1782 get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited)
1784 unsigned nargs = gimple_phi_num_args (phi);
1786 /* Through a single-argument PHI we can simply look through. */
1788 return PHI_ARG_DEF (phi, 0);
1790 /* For two arguments try to skip non-aliasing code until we hit
1791 the phi argument definition that dominates the other one. */
1794 tree arg0 = PHI_ARG_DEF (phi, 0);
1795 tree arg1 = PHI_ARG_DEF (phi, 1);
1796 gimple def0 = SSA_NAME_DEF_STMT (arg0);
1797 gimple def1 = SSA_NAME_DEF_STMT (arg1);
1802 else if (gimple_nop_p (def0)
1803 || (!gimple_nop_p (def1)
1804 && dominated_by_p (CDI_DOMINATORS,
1805 gimple_bb (def1), gimple_bb (def0))))
1807 if (maybe_skip_until (phi, arg0, ref, arg1, visited))
1810 else if (gimple_nop_p (def1)
1811 || dominated_by_p (CDI_DOMINATORS,
1812 gimple_bb (def0), gimple_bb (def1)))
1814 if (maybe_skip_until (phi, arg1, ref, arg0, visited))
1817 /* Special case of a diamond:
1819 goto (cond) ? L1 : L2
1820 L1: store1 = ... #MEM_2 = vuse(MEM_1)
1822 L2: store2 = ... #MEM_3 = vuse(MEM_1)
1823 L3: MEM_4 = PHI<MEM_2, MEM_3>
1824 We were called with the PHI at L3, MEM_2 and MEM_3 don't
1825 dominate each other, but still we can easily skip this PHI node
1826 if we recognize that the vuse MEM operand is the same for both,
1827 and that we can skip both statements (they don't clobber us).
1828 This is still linear. Don't use maybe_skip_until, that might
1829 potentially be slow. */
1830 else if ((common_vuse = gimple_vuse (def0))
1831 && common_vuse == gimple_vuse (def1))
1833 if (!stmt_may_clobber_ref_p_1 (def0, ref)
1834 && !stmt_may_clobber_ref_p_1 (def1, ref))
1842 /* Based on the memory reference REF and its virtual use VUSE call
1843 WALKER for each virtual use that is equivalent to VUSE, including VUSE
1844 itself. That is, for each virtual use for which its defining statement
1845 does not clobber REF.
1847 WALKER is called with REF, the current virtual use and DATA. If
1848 WALKER returns non-NULL the walk stops and its result is returned.
1849 At the end of a non-successful walk NULL is returned.
1851 TRANSLATE if non-NULL is called with a pointer to REF, the virtual
1852 use which definition is a statement that may clobber REF and DATA.
1853 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
1854 If TRANSLATE returns non-NULL the walk stops and its result is returned.
1855 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
1856 to adjust REF and *DATA to make that valid.
1858 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
1861 walk_non_aliased_vuses (ao_ref *ref, tree vuse,
1862 void *(*walker)(ao_ref *, tree, void *),
1863 void *(*translate)(ao_ref *, tree, void *), void *data)
1865 bitmap visited = NULL;
1868 timevar_push (TV_ALIAS_STMT_WALK);
1874 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1875 res = (*walker) (ref, vuse, data);
1879 def_stmt = SSA_NAME_DEF_STMT (vuse);
1880 if (gimple_nop_p (def_stmt))
1882 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1883 vuse = get_continuation_for_phi (def_stmt, ref, &visited);
1886 if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
1890 res = (*translate) (ref, vuse, data);
1891 /* Failed lookup and translation. */
1892 if (res == (void *)-1)
1897 /* Lookup succeeded. */
1898 else if (res != NULL)
1900 /* Translation succeeded, continue walking. */
1902 vuse = gimple_vuse (def_stmt);
1908 BITMAP_FREE (visited);
1910 timevar_pop (TV_ALIAS_STMT_WALK);
1916 /* Based on the memory reference REF call WALKER for each vdef which
1917 defining statement may clobber REF, starting with VDEF. If REF
1918 is NULL_TREE, each defining statement is visited.
1920 WALKER is called with REF, the current vdef and DATA. If WALKER
1921 returns true the walk is stopped, otherwise it continues.
1923 At PHI nodes walk_aliased_vdefs forks into one walk for reach
1924 PHI argument (but only one walk continues on merge points), the
1925 return value is true if any of the walks was successful.
1927 The function returns the number of statements walked. */
1930 walk_aliased_vdefs_1 (ao_ref *ref, tree vdef,
1931 bool (*walker)(ao_ref *, tree, void *), void *data,
1932 bitmap *visited, unsigned int cnt)
1936 gimple def_stmt = SSA_NAME_DEF_STMT (vdef);
1939 && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef)))
1942 if (gimple_nop_p (def_stmt))
1944 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1948 *visited = BITMAP_ALLOC (NULL);
1949 for (i = 0; i < gimple_phi_num_args (def_stmt); ++i)
1950 cnt += walk_aliased_vdefs_1 (ref, gimple_phi_arg_def (def_stmt, i),
1951 walker, data, visited, 0);
1955 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1958 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1959 && (*walker) (ref, vdef, data))
1962 vdef = gimple_vuse (def_stmt);
1968 walk_aliased_vdefs (ao_ref *ref, tree vdef,
1969 bool (*walker)(ao_ref *, tree, void *), void *data,
1972 bitmap local_visited = NULL;
1975 timevar_push (TV_ALIAS_STMT_WALK);
1977 ret = walk_aliased_vdefs_1 (ref, vdef, walker, data,
1978 visited ? visited : &local_visited, 0);
1980 BITMAP_FREE (local_visited);
1982 timevar_pop (TV_ALIAS_STMT_WALK);