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"
43 #include "ipa-type-escape.h"
47 #include "pointer-set.h"
48 #include "alloc-pool.h"
49 #include "tree-ssa-alias.h"
51 /* Broad overview of how alias analysis on gimple works:
53 Statements clobbering or using memory are linked through the
54 virtual operand factored use-def chain. The virtual operand
55 is unique per function, its symbol is accessible via gimple_vop (cfun).
56 Virtual operands are used for efficiently walking memory statements
57 in the gimple IL and are useful for things like value-numbering as
58 a generation count for memory references.
60 SSA_NAME pointers may have associated points-to information
61 accessible via the SSA_NAME_PTR_INFO macro. Flow-insensitive
62 points-to information is (re-)computed by the TODO_rebuild_alias
63 pass manager todo. Points-to information is also used for more
64 precise tracking of call-clobbered and call-used variables and
65 related disambiguations.
67 This file contains functions for disambiguating memory references,
68 the so called alias-oracle and tools for walking of the gimple IL.
70 The main alias-oracle entry-points are
72 bool stmt_may_clobber_ref_p (gimple, tree)
74 This function queries if a statement may invalidate (parts of)
75 the memory designated by the reference tree argument.
77 bool ref_maybe_used_by_stmt_p (gimple, tree)
79 This function queries if a statement may need (parts of) the
80 memory designated by the reference tree argument.
82 There are variants of these functions that only handle the call
83 part of a statement, call_may_clobber_ref_p and ref_maybe_used_by_call_p.
84 Note that these do not disambiguate against a possible call lhs.
86 bool refs_may_alias_p (tree, tree)
88 This function tries to disambiguate two reference trees.
90 bool ptr_deref_may_alias_global_p (tree)
92 This function queries if dereferencing a pointer variable may
95 More low-level disambiguators are available and documented in
96 this file. Low-level disambiguators dealing with points-to
97 information are in tree-ssa-structalias.c. */
100 /* Query statistics for the different low-level disambiguators.
101 A high-level query may trigger multiple of them. */
104 unsigned HOST_WIDE_INT refs_may_alias_p_may_alias;
105 unsigned HOST_WIDE_INT refs_may_alias_p_no_alias;
106 unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_may_alias;
107 unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_no_alias;
108 unsigned HOST_WIDE_INT call_may_clobber_ref_p_may_alias;
109 unsigned HOST_WIDE_INT call_may_clobber_ref_p_no_alias;
113 dump_alias_stats (FILE *s)
115 fprintf (s, "\nAlias oracle query stats:\n");
116 fprintf (s, " refs_may_alias_p: "
117 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
118 HOST_WIDE_INT_PRINT_DEC" queries\n",
119 alias_stats.refs_may_alias_p_no_alias,
120 alias_stats.refs_may_alias_p_no_alias
121 + alias_stats.refs_may_alias_p_may_alias);
122 fprintf (s, " ref_maybe_used_by_call_p: "
123 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
124 HOST_WIDE_INT_PRINT_DEC" queries\n",
125 alias_stats.ref_maybe_used_by_call_p_no_alias,
126 alias_stats.refs_may_alias_p_no_alias
127 + alias_stats.ref_maybe_used_by_call_p_may_alias);
128 fprintf (s, " call_may_clobber_ref_p: "
129 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
130 HOST_WIDE_INT_PRINT_DEC" queries\n",
131 alias_stats.call_may_clobber_ref_p_no_alias,
132 alias_stats.call_may_clobber_ref_p_no_alias
133 + alias_stats.call_may_clobber_ref_p_may_alias);
137 /* Return true, if dereferencing PTR may alias with a global variable. */
140 ptr_deref_may_alias_global_p (tree ptr)
142 struct ptr_info_def *pi;
144 /* If we end up with a pointer constant here that may point
146 if (TREE_CODE (ptr) != SSA_NAME)
149 pi = SSA_NAME_PTR_INFO (ptr);
151 /* If we do not have points-to information for this variable,
156 /* ??? This does not use TBAA to prune globals ptr may not access. */
157 return pt_solution_includes_global (&pi->pt);
160 /* Return true if dereferencing PTR may alias DECL.
161 The caller is responsible for applying TBAA to see if PTR
162 may access DECL at all. */
165 ptr_deref_may_alias_decl_p (tree ptr, tree decl)
167 struct ptr_info_def *pi;
169 /* Conversions are irrelevant for points-to information and
170 data-dependence analysis can feed us those. */
173 /* Anything we do not explicilty handle aliases. */
174 if ((TREE_CODE (ptr) != SSA_NAME
175 && TREE_CODE (ptr) != ADDR_EXPR
176 && TREE_CODE (ptr) != POINTER_PLUS_EXPR)
177 || !POINTER_TYPE_P (TREE_TYPE (ptr))
178 || (TREE_CODE (decl) != VAR_DECL
179 && TREE_CODE (decl) != PARM_DECL
180 && TREE_CODE (decl) != RESULT_DECL))
183 /* Disregard pointer offsetting. */
184 if (TREE_CODE (ptr) == POINTER_PLUS_EXPR)
188 ptr = TREE_OPERAND (ptr, 0);
190 while (TREE_CODE (ptr) == POINTER_PLUS_EXPR);
191 return ptr_deref_may_alias_decl_p (ptr, decl);
194 /* ADDR_EXPR pointers either just offset another pointer or directly
195 specify the pointed-to set. */
196 if (TREE_CODE (ptr) == ADDR_EXPR)
198 tree base = get_base_address (TREE_OPERAND (ptr, 0));
200 && (INDIRECT_REF_P (base)
201 || TREE_CODE (base) == MEM_REF))
202 ptr = TREE_OPERAND (base, 0);
207 && CONSTANT_CLASS_P (base))
213 /* Non-aliased variables can not be pointed to. */
214 if (!may_be_aliased (decl))
217 /* If we do not have useful points-to information for this pointer
218 we cannot disambiguate anything else. */
219 pi = SSA_NAME_PTR_INFO (ptr);
223 /* If the decl can be used as a restrict tag and we have a restrict
224 pointer and that pointers points-to set doesn't contain this decl
225 then they can't alias. */
226 if (DECL_RESTRICTED_P (decl)
227 && TYPE_RESTRICT (TREE_TYPE (ptr))
228 && pi->pt.vars_contains_restrict)
229 return bitmap_bit_p (pi->pt.vars, DECL_PT_UID (decl));
231 return pt_solution_includes (&pi->pt, decl);
234 /* Return true if dereferenced PTR1 and PTR2 may alias.
235 The caller is responsible for applying TBAA to see if accesses
236 through PTR1 and PTR2 may conflict at all. */
239 ptr_derefs_may_alias_p (tree ptr1, tree ptr2)
241 struct ptr_info_def *pi1, *pi2;
243 /* Conversions are irrelevant for points-to information and
244 data-dependence analysis can feed us those. */
248 /* Anything we do not explicilty handle aliases. */
249 if ((TREE_CODE (ptr1) != SSA_NAME
250 && TREE_CODE (ptr1) != ADDR_EXPR
251 && TREE_CODE (ptr1) != POINTER_PLUS_EXPR)
252 || (TREE_CODE (ptr2) != SSA_NAME
253 && TREE_CODE (ptr2) != ADDR_EXPR
254 && TREE_CODE (ptr2) != POINTER_PLUS_EXPR)
255 || !POINTER_TYPE_P (TREE_TYPE (ptr1))
256 || !POINTER_TYPE_P (TREE_TYPE (ptr2)))
259 /* Disregard pointer offsetting. */
260 if (TREE_CODE (ptr1) == POINTER_PLUS_EXPR)
264 ptr1 = TREE_OPERAND (ptr1, 0);
266 while (TREE_CODE (ptr1) == POINTER_PLUS_EXPR);
267 return ptr_derefs_may_alias_p (ptr1, ptr2);
269 if (TREE_CODE (ptr2) == POINTER_PLUS_EXPR)
273 ptr2 = TREE_OPERAND (ptr2, 0);
275 while (TREE_CODE (ptr2) == POINTER_PLUS_EXPR);
276 return ptr_derefs_may_alias_p (ptr1, ptr2);
279 /* ADDR_EXPR pointers either just offset another pointer or directly
280 specify the pointed-to set. */
281 if (TREE_CODE (ptr1) == ADDR_EXPR)
283 tree base = get_base_address (TREE_OPERAND (ptr1, 0));
285 && (INDIRECT_REF_P (base)
286 || TREE_CODE (base) == MEM_REF))
287 ptr1 = TREE_OPERAND (base, 0);
290 return ptr_deref_may_alias_decl_p (ptr2, base);
294 if (TREE_CODE (ptr2) == ADDR_EXPR)
296 tree base = get_base_address (TREE_OPERAND (ptr2, 0));
298 && (INDIRECT_REF_P (base)
299 || TREE_CODE (base) == MEM_REF))
300 ptr2 = TREE_OPERAND (base, 0);
303 return ptr_deref_may_alias_decl_p (ptr1, base);
308 /* We may end up with two empty points-to solutions for two same pointers.
309 In this case we still want to say both pointers alias, so shortcut
314 /* If we do not have useful points-to information for either pointer
315 we cannot disambiguate anything else. */
316 pi1 = SSA_NAME_PTR_INFO (ptr1);
317 pi2 = SSA_NAME_PTR_INFO (ptr2);
321 /* If both pointers are restrict-qualified try to disambiguate
322 with restrict information. */
323 if (TYPE_RESTRICT (TREE_TYPE (ptr1))
324 && TYPE_RESTRICT (TREE_TYPE (ptr2))
325 && !pt_solutions_same_restrict_base (&pi1->pt, &pi2->pt))
328 /* ??? This does not use TBAA to prune decls from the intersection
329 that not both pointers may access. */
330 return pt_solutions_intersect (&pi1->pt, &pi2->pt);
333 /* Return true if dereferencing PTR may alias *REF.
334 The caller is responsible for applying TBAA to see if PTR
335 may access *REF at all. */
338 ptr_deref_may_alias_ref_p_1 (tree ptr, ao_ref *ref)
340 tree base = ao_ref_base (ref);
342 if (INDIRECT_REF_P (base)
343 || TREE_CODE (base) == MEM_REF)
344 return ptr_derefs_may_alias_p (ptr, TREE_OPERAND (base, 0));
345 else if (SSA_VAR_P (base))
346 return ptr_deref_may_alias_decl_p (ptr, base);
352 /* Dump alias information on FILE. */
355 dump_alias_info (FILE *file)
359 = lang_hooks.decl_printable_name (current_function_decl, 2);
360 referenced_var_iterator rvi;
363 fprintf (file, "\n\nAlias information for %s\n\n", funcname);
365 fprintf (file, "Aliased symbols\n\n");
367 FOR_EACH_REFERENCED_VAR (cfun, var, rvi)
369 if (may_be_aliased (var))
370 dump_variable (file, var);
373 fprintf (file, "\nCall clobber information\n");
375 fprintf (file, "\nESCAPED");
376 dump_points_to_solution (file, &cfun->gimple_df->escaped);
378 fprintf (file, "\n\nFlow-insensitive points-to information\n\n");
380 for (i = 1; i < num_ssa_names; i++)
382 tree ptr = ssa_name (i);
383 struct ptr_info_def *pi;
386 || SSA_NAME_IN_FREE_LIST (ptr))
389 pi = SSA_NAME_PTR_INFO (ptr);
391 dump_points_to_info_for (file, ptr);
394 fprintf (file, "\n");
398 /* Dump alias information on stderr. */
401 debug_alias_info (void)
403 dump_alias_info (stderr);
407 /* Dump the points-to set *PT into FILE. */
410 dump_points_to_solution (FILE *file, struct pt_solution *pt)
413 fprintf (file, ", points-to anything");
416 fprintf (file, ", points-to non-local");
419 fprintf (file, ", points-to escaped");
422 fprintf (file, ", points-to unit escaped");
425 fprintf (file, ", points-to NULL");
429 fprintf (file, ", points-to vars: ");
430 dump_decl_set (file, pt->vars);
431 if (pt->vars_contains_global)
432 fprintf (file, " (includes global vars)");
433 if (pt->vars_contains_restrict)
434 fprintf (file, " (includes restrict tags)");
438 /* Dump points-to information for SSA_NAME PTR into FILE. */
441 dump_points_to_info_for (FILE *file, tree ptr)
443 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
445 print_generic_expr (file, ptr, dump_flags);
448 dump_points_to_solution (file, &pi->pt);
450 fprintf (file, ", points-to anything");
452 fprintf (file, "\n");
456 /* Dump points-to information for VAR into stderr. */
459 debug_points_to_info_for (tree var)
461 dump_points_to_info_for (stderr, var);
465 /* Initializes the alias-oracle reference representation *R from REF. */
468 ao_ref_init (ao_ref *r, tree ref)
475 r->ref_alias_set = -1;
476 r->base_alias_set = -1;
479 /* Returns the base object of the memory reference *REF. */
482 ao_ref_base (ao_ref *ref)
486 ref->base = get_ref_base_and_extent (ref->ref, &ref->offset, &ref->size,
491 /* Returns the base object alias set of the memory reference *REF. */
493 static alias_set_type
494 ao_ref_base_alias_set (ao_ref *ref)
497 if (ref->base_alias_set != -1)
498 return ref->base_alias_set;
502 while (handled_component_p (base_ref))
503 base_ref = TREE_OPERAND (base_ref, 0);
504 ref->base_alias_set = get_alias_set (base_ref);
505 return ref->base_alias_set;
508 /* Returns the reference alias set of the memory reference *REF. */
511 ao_ref_alias_set (ao_ref *ref)
513 if (ref->ref_alias_set != -1)
514 return ref->ref_alias_set;
515 ref->ref_alias_set = get_alias_set (ref->ref);
516 return ref->ref_alias_set;
519 /* Init an alias-oracle reference representation from a gimple pointer
520 PTR and a gimple size SIZE in bytes. If SIZE is NULL_TREE the the
521 size is assumed to be unknown. The access is assumed to be only
522 to or after of the pointer target, not before it. */
525 ao_ref_init_from_ptr_and_size (ao_ref *ref, tree ptr, tree size)
527 HOST_WIDE_INT t1, t2;
528 ref->ref = NULL_TREE;
529 if (TREE_CODE (ptr) == ADDR_EXPR)
530 ref->base = get_ref_base_and_extent (TREE_OPERAND (ptr, 0),
531 &ref->offset, &t1, &t2);
534 ref->base = build2 (MEM_REF, char_type_node,
535 ptr, null_pointer_node);
539 && host_integerp (size, 0)
540 && TREE_INT_CST_LOW (size) * 8 / 8 == TREE_INT_CST_LOW (size))
541 ref->max_size = ref->size = TREE_INT_CST_LOW (size) * 8;
543 ref->max_size = ref->size = -1;
544 ref->ref_alias_set = 0;
545 ref->base_alias_set = 0;
548 /* Return 1 if TYPE1 and TYPE2 are to be considered equivalent for the
549 purpose of TBAA. Return 0 if they are distinct and -1 if we cannot
553 same_type_for_tbaa (tree type1, tree type2)
555 type1 = TYPE_MAIN_VARIANT (type1);
556 type2 = TYPE_MAIN_VARIANT (type2);
558 /* If we would have to do structural comparison bail out. */
559 if (TYPE_STRUCTURAL_EQUALITY_P (type1)
560 || TYPE_STRUCTURAL_EQUALITY_P (type2))
563 /* Compare the canonical types. */
564 if (TYPE_CANONICAL (type1) == TYPE_CANONICAL (type2))
567 /* ??? Array types are not properly unified in all cases as we have
568 spurious changes in the index types for example. Removing this
569 causes all sorts of problems with the Fortran frontend. */
570 if (TREE_CODE (type1) == ARRAY_TYPE
571 && TREE_CODE (type2) == ARRAY_TYPE)
574 /* ??? In Ada, an lvalue of an unconstrained type can be used to access an
575 object of one of its constrained subtypes, e.g. when a function with an
576 unconstrained parameter passed by reference is called on an object and
577 inlined. But, even in the case of a fixed size, type and subtypes are
578 not equivalent enough as to share the same TYPE_CANONICAL, since this
579 would mean that conversions between them are useless, whereas they are
580 not (e.g. type and subtypes can have different modes). So, in the end,
581 they are only guaranteed to have the same alias set. */
582 if (get_alias_set (type1) == get_alias_set (type2))
585 /* The types are known to be not equal. */
589 /* Determine if the two component references REF1 and REF2 which are
590 based on access types TYPE1 and TYPE2 and of which at least one is based
591 on an indirect reference may alias. REF2 is the only one that can
592 be a decl in which case REF2_IS_DECL is true.
593 REF1_ALIAS_SET, BASE1_ALIAS_SET, REF2_ALIAS_SET and BASE2_ALIAS_SET
594 are the respective alias sets. */
597 aliasing_component_refs_p (tree ref1,
598 alias_set_type ref1_alias_set,
599 alias_set_type base1_alias_set,
600 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
602 alias_set_type ref2_alias_set,
603 alias_set_type base2_alias_set,
604 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
607 /* If one reference is a component references through pointers try to find a
608 common base and apply offset based disambiguation. This handles
610 struct A { int i; int j; } *q;
611 struct B { struct A a; int k; } *p;
612 disambiguating q->i and p->a.j. */
618 /* Choose bases and base types to search for. */
620 while (handled_component_p (base1))
621 base1 = TREE_OPERAND (base1, 0);
622 type1 = TREE_TYPE (base1);
624 while (handled_component_p (base2))
625 base2 = TREE_OPERAND (base2, 0);
626 type2 = TREE_TYPE (base2);
628 /* Now search for the type1 in the access path of ref2. This
629 would be a common base for doing offset based disambiguation on. */
631 while (handled_component_p (*refp)
632 && same_type_for_tbaa (TREE_TYPE (*refp), type1) == 0)
633 refp = &TREE_OPERAND (*refp, 0);
634 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type1);
635 /* If we couldn't compare types we have to bail out. */
638 else if (same_p == 1)
640 HOST_WIDE_INT offadj, sztmp, msztmp;
641 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
643 get_ref_base_and_extent (base1, &offadj, &sztmp, &msztmp);
645 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
647 /* If we didn't find a common base, try the other way around. */
649 while (handled_component_p (*refp)
650 && same_type_for_tbaa (TREE_TYPE (*refp), type2) == 0)
651 refp = &TREE_OPERAND (*refp, 0);
652 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type2);
653 /* If we couldn't compare types we have to bail out. */
656 else if (same_p == 1)
658 HOST_WIDE_INT offadj, sztmp, msztmp;
659 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
661 get_ref_base_and_extent (base2, &offadj, &sztmp, &msztmp);
663 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
666 /* If we have two type access paths B1.path1 and B2.path2 they may
667 only alias if either B1 is in B2.path2 or B2 is in B1.path1.
668 But we can still have a path that goes B1.path1...B2.path2 with
669 a part that we do not see. So we can only disambiguate now
670 if there is no B2 in the tail of path1 and no B1 on the
672 if (base1_alias_set == ref2_alias_set
673 || alias_set_subset_of (base1_alias_set, ref2_alias_set))
675 /* If this is ptr vs. decl then we know there is no ptr ... decl path. */
677 return (base2_alias_set == ref1_alias_set
678 || alias_set_subset_of (base2_alias_set, ref1_alias_set));
682 /* Return true if two memory references based on the variables BASE1
683 and BASE2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
684 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. */
687 decl_refs_may_alias_p (tree base1,
688 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
690 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
692 gcc_assert (SSA_VAR_P (base1) && SSA_VAR_P (base2));
694 /* If both references are based on different variables, they cannot alias. */
698 /* If both references are based on the same variable, they cannot alias if
699 the accesses do not overlap. */
700 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
703 /* Return true if an indirect reference based on *PTR1 constrained
704 to [OFFSET1, OFFSET1 + MAX_SIZE1) may alias a variable based on BASE2
705 constrained to [OFFSET2, OFFSET2 + MAX_SIZE2). *PTR1 and BASE2 have
706 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
707 in which case they are computed on-demand. REF1 and REF2
708 if non-NULL are the complete memory reference trees. */
711 indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
712 HOST_WIDE_INT offset1,
713 HOST_WIDE_INT max_size1 ATTRIBUTE_UNUSED,
714 alias_set_type ref1_alias_set,
715 alias_set_type base1_alias_set,
716 tree ref2 ATTRIBUTE_UNUSED, tree base2,
717 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
718 alias_set_type ref2_alias_set,
719 alias_set_type base2_alias_set, bool tbaa_p)
722 tree ptrtype1, dbase2;
723 HOST_WIDE_INT offset1p = offset1, offset2p = offset2;
724 HOST_WIDE_INT doffset1, doffset2;
726 ptr1 = TREE_OPERAND (base1, 0);
728 /* The offset embedded in MEM_REFs can be negative. Bias them
729 so that the resulting offset adjustment is positive. */
730 if (TREE_CODE (base1) == MEM_REF
731 || TREE_CODE (base1) == TARGET_MEM_REF)
733 double_int moff = mem_ref_offset (base1);
734 moff = double_int_lshift (moff,
736 ? 3 : exact_log2 (BITS_PER_UNIT),
737 HOST_BITS_PER_DOUBLE_INT, true);
738 if (double_int_negative_p (moff))
739 offset2p += double_int_neg (moff).low;
741 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 ??? IVOPTs creates bases that do not honor this restriction,
749 so do not apply this optimization for TARGET_MEM_REFs. */
750 if (TREE_CODE (base1) != TARGET_MEM_REF
751 && !ranges_overlap_p (MAX (0, offset1p), -1, offset2p, max_size2))
753 /* They also cannot alias if the pointer may not point to the decl. */
754 if (!ptr_deref_may_alias_decl_p (ptr1, base2))
757 /* Disambiguations that rely on strict aliasing rules follow. */
758 if (!flag_strict_aliasing || !tbaa_p)
761 if (TREE_CODE (base1) == MEM_REF)
762 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
763 else if (TREE_CODE (base1) == TARGET_MEM_REF)
764 ptrtype1 = TREE_TYPE (TMR_OFFSET (base1));
766 ptrtype1 = TREE_TYPE (ptr1);
768 /* If the alias set for a pointer access is zero all bets are off. */
769 if (base1_alias_set == -1)
770 base1_alias_set = get_deref_alias_set (ptrtype1);
771 if (base1_alias_set == 0)
773 if (base2_alias_set == -1)
774 base2_alias_set = get_alias_set (base2);
776 /* When we are trying to disambiguate an access with a pointer dereference
777 as base versus one with a decl as base we can use both the size
778 of the decl and its dynamic type for extra disambiguation.
779 ??? We do not know anything about the dynamic type of the decl
780 other than that its alias-set contains base2_alias_set as a subset
781 which does not help us here. */
782 /* As we know nothing useful about the dynamic type of the decl just
783 use the usual conflict check rather than a subset test.
784 ??? We could introduce -fvery-strict-aliasing when the language
785 does not allow decls to have a dynamic type that differs from their
786 static type. Then we can check
787 !alias_set_subset_of (base1_alias_set, base2_alias_set) instead. */
788 if (base1_alias_set != base2_alias_set
789 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
791 /* If the size of the access relevant for TBAA through the pointer
792 is bigger than the size of the decl we can't possibly access the
793 decl via that pointer. */
794 if (DECL_SIZE (base2) && COMPLETE_TYPE_P (TREE_TYPE (ptrtype1))
795 && TREE_CODE (DECL_SIZE (base2)) == INTEGER_CST
796 && TREE_CODE (TYPE_SIZE (TREE_TYPE (ptrtype1))) == INTEGER_CST
797 /* ??? This in turn may run afoul when a decl of type T which is
798 a member of union type U is accessed through a pointer to
799 type U and sizeof T is smaller than sizeof U. */
800 && TREE_CODE (TREE_TYPE (ptrtype1)) != UNION_TYPE
801 && TREE_CODE (TREE_TYPE (ptrtype1)) != QUAL_UNION_TYPE
802 && tree_int_cst_lt (DECL_SIZE (base2), TYPE_SIZE (TREE_TYPE (ptrtype1))))
808 /* If the decl is accressed via a MEM_REF, reconstruct the base
809 we can use for TBAA and an appropriately adjusted offset. */
811 while (handled_component_p (dbase2))
812 dbase2 = TREE_OPERAND (dbase2, 0);
815 if (TREE_CODE (dbase2) == MEM_REF
816 || TREE_CODE (dbase2) == TARGET_MEM_REF)
818 double_int moff = mem_ref_offset (dbase2);
819 moff = double_int_lshift (moff,
821 ? 3 : exact_log2 (BITS_PER_UNIT),
822 HOST_BITS_PER_DOUBLE_INT, true);
823 if (double_int_negative_p (moff))
824 doffset1 -= double_int_neg (moff).low;
826 doffset2 -= moff.low;
829 /* If either reference is view-converted, give up now. */
830 if (same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) != 1
831 || same_type_for_tbaa (TREE_TYPE (dbase2),
832 TREE_TYPE (reference_alias_ptr_type (dbase2))) != 1)
835 /* If both references are through the same type, they do not alias
836 if the accesses do not overlap. This does extra disambiguation
837 for mixed/pointer accesses but requires strict aliasing.
838 For MEM_REFs we require that the component-ref offset we computed
839 is relative to the start of the type which we ensure by
840 comparing rvalue and access type and disregarding the constant
842 if ((TREE_CODE (base1) != TARGET_MEM_REF
843 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
844 && same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (dbase2)) == 1)
845 return ranges_overlap_p (doffset1, max_size1, doffset2, max_size2);
847 /* Do access-path based disambiguation. */
849 && handled_component_p (ref1)
850 && handled_component_p (ref2)
851 && TREE_CODE (base1) != TARGET_MEM_REF
852 && (TREE_CODE (base1) != MEM_REF
853 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1))
854 return aliasing_component_refs_p (ref1,
855 ref1_alias_set, base1_alias_set,
858 ref2_alias_set, base2_alias_set,
859 offset2, max_size2, true);
864 /* Return true if two indirect references based on *PTR1
865 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
866 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have
867 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
868 in which case they are computed on-demand. REF1 and REF2
869 if non-NULL are the complete memory reference trees. */
872 indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
873 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
874 alias_set_type ref1_alias_set,
875 alias_set_type base1_alias_set,
876 tree ref2 ATTRIBUTE_UNUSED, tree base2,
877 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
878 alias_set_type ref2_alias_set,
879 alias_set_type base2_alias_set, bool tbaa_p)
883 tree ptrtype1, ptrtype2;
885 ptr1 = TREE_OPERAND (base1, 0);
886 ptr2 = TREE_OPERAND (base2, 0);
888 /* If both bases are based on pointers they cannot alias if they may not
889 point to the same memory object or if they point to the same object
890 and the accesses do not overlap. */
891 if ((!cfun || gimple_in_ssa_p (cfun))
892 && operand_equal_p (ptr1, ptr2, 0)
893 && (((TREE_CODE (base1) != TARGET_MEM_REF
894 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
895 && (TREE_CODE (base2) != TARGET_MEM_REF
896 || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2))))
897 || (TREE_CODE (base1) == TARGET_MEM_REF
898 && TREE_CODE (base2) == TARGET_MEM_REF
899 && (TMR_STEP (base1) == TMR_STEP (base2)
900 || (TMR_STEP (base1) && TMR_STEP (base2)
901 && operand_equal_p (TMR_STEP (base1),
902 TMR_STEP (base2), 0)))
903 && (TMR_INDEX (base1) == TMR_INDEX (base2)
904 || (TMR_INDEX (base1) && TMR_INDEX (base2)
905 && operand_equal_p (TMR_INDEX (base1),
906 TMR_INDEX (base2), 0)))
907 && (TMR_INDEX2 (base1) == TMR_INDEX2 (base2)
908 || (TMR_INDEX2 (base1) && TMR_INDEX2 (base2)
909 && operand_equal_p (TMR_INDEX2 (base1),
910 TMR_INDEX2 (base2), 0))))))
912 /* The offset embedded in MEM_REFs can be negative. Bias them
913 so that the resulting offset adjustment is positive. */
914 if (TREE_CODE (base1) == MEM_REF
915 || TREE_CODE (base1) == TARGET_MEM_REF)
917 double_int moff = mem_ref_offset (base1);
918 moff = double_int_lshift (moff,
920 ? 3 : exact_log2 (BITS_PER_UNIT),
921 HOST_BITS_PER_DOUBLE_INT, true);
922 if (double_int_negative_p (moff))
923 offset2 += double_int_neg (moff).low;
927 if (TREE_CODE (base2) == MEM_REF
928 || TREE_CODE (base2) == TARGET_MEM_REF)
930 double_int moff = mem_ref_offset (base2);
931 moff = double_int_lshift (moff,
933 ? 3 : exact_log2 (BITS_PER_UNIT),
934 HOST_BITS_PER_DOUBLE_INT, true);
935 if (double_int_negative_p (moff))
936 offset1 += double_int_neg (moff).low;
940 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
942 if (!ptr_derefs_may_alias_p (ptr1, ptr2))
945 /* Disambiguations that rely on strict aliasing rules follow. */
946 if (!flag_strict_aliasing || !tbaa_p)
949 if (TREE_CODE (base1) == MEM_REF)
950 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
951 else if (TREE_CODE (base1) == TARGET_MEM_REF)
952 ptrtype1 = TREE_TYPE (TMR_OFFSET (base1));
954 ptrtype1 = TREE_TYPE (ptr1);
955 if (TREE_CODE (base2) == MEM_REF)
956 ptrtype2 = TREE_TYPE (TREE_OPERAND (base2, 1));
957 else if (TREE_CODE (base2) == TARGET_MEM_REF)
958 ptrtype2 = TREE_TYPE (TMR_OFFSET (base2));
960 ptrtype2 = TREE_TYPE (ptr2);
962 /* If the alias set for a pointer access is zero all bets are off. */
963 if (base1_alias_set == -1)
964 base1_alias_set = get_deref_alias_set (ptrtype1);
965 if (base1_alias_set == 0)
967 if (base2_alias_set == -1)
968 base2_alias_set = get_deref_alias_set (ptrtype2);
969 if (base2_alias_set == 0)
972 /* If both references are through the same type, they do not alias
973 if the accesses do not overlap. This does extra disambiguation
974 for mixed/pointer accesses but requires strict aliasing. */
975 if ((TREE_CODE (base1) != TARGET_MEM_REF
976 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
977 && (TREE_CODE (base2) != TARGET_MEM_REF
978 || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2)))
979 && same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1
980 && same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1
981 && same_type_for_tbaa (TREE_TYPE (ptrtype1),
982 TREE_TYPE (ptrtype2)) == 1)
983 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
985 /* Do type-based disambiguation. */
986 if (base1_alias_set != base2_alias_set
987 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
990 /* Do access-path based disambiguation. */
992 && handled_component_p (ref1)
993 && handled_component_p (ref2)
994 && TREE_CODE (base1) != TARGET_MEM_REF
995 && TREE_CODE (base2) != TARGET_MEM_REF
996 && (TREE_CODE (base1) != MEM_REF
997 || same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1)
998 && (TREE_CODE (base2) != MEM_REF
999 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1))
1000 return aliasing_component_refs_p (ref1,
1001 ref1_alias_set, base1_alias_set,
1004 ref2_alias_set, base2_alias_set,
1005 offset2, max_size2, false);
1010 /* Return true, if the two memory references REF1 and REF2 may alias. */
1013 refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
1016 HOST_WIDE_INT offset1 = 0, offset2 = 0;
1017 HOST_WIDE_INT max_size1 = -1, max_size2 = -1;
1018 bool var1_p, var2_p, ind1_p, ind2_p;
1020 gcc_checking_assert ((!ref1->ref
1021 || TREE_CODE (ref1->ref) == SSA_NAME
1022 || DECL_P (ref1->ref)
1023 || TREE_CODE (ref1->ref) == STRING_CST
1024 || handled_component_p (ref1->ref)
1025 || INDIRECT_REF_P (ref1->ref)
1026 || TREE_CODE (ref1->ref) == MEM_REF
1027 || TREE_CODE (ref1->ref) == TARGET_MEM_REF)
1029 || TREE_CODE (ref2->ref) == SSA_NAME
1030 || DECL_P (ref2->ref)
1031 || TREE_CODE (ref2->ref) == STRING_CST
1032 || handled_component_p (ref2->ref)
1033 || INDIRECT_REF_P (ref2->ref)
1034 || TREE_CODE (ref2->ref) == MEM_REF
1035 || TREE_CODE (ref2->ref) == TARGET_MEM_REF));
1037 /* Decompose the references into their base objects and the access. */
1038 base1 = ao_ref_base (ref1);
1039 offset1 = ref1->offset;
1040 max_size1 = ref1->max_size;
1041 base2 = ao_ref_base (ref2);
1042 offset2 = ref2->offset;
1043 max_size2 = ref2->max_size;
1045 /* We can end up with registers or constants as bases for example from
1046 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
1047 which is seen as a struct copy. */
1048 if (TREE_CODE (base1) == SSA_NAME
1049 || TREE_CODE (base1) == CONST_DECL
1050 || TREE_CODE (base1) == CONSTRUCTOR
1051 || TREE_CODE (base1) == ADDR_EXPR
1052 || CONSTANT_CLASS_P (base1)
1053 || TREE_CODE (base2) == SSA_NAME
1054 || TREE_CODE (base2) == CONST_DECL
1055 || TREE_CODE (base2) == CONSTRUCTOR
1056 || TREE_CODE (base2) == ADDR_EXPR
1057 || CONSTANT_CLASS_P (base2))
1060 /* We can end up refering to code via function and label decls.
1061 As we likely do not properly track code aliases conservatively
1063 if (TREE_CODE (base1) == FUNCTION_DECL
1064 || TREE_CODE (base1) == LABEL_DECL
1065 || TREE_CODE (base2) == FUNCTION_DECL
1066 || TREE_CODE (base2) == LABEL_DECL)
1069 /* Defer to simple offset based disambiguation if we have
1070 references based on two decls. Do this before defering to
1071 TBAA to handle must-alias cases in conformance with the
1072 GCC extension of allowing type-punning through unions. */
1073 var1_p = SSA_VAR_P (base1);
1074 var2_p = SSA_VAR_P (base2);
1075 if (var1_p && var2_p)
1076 return decl_refs_may_alias_p (base1, offset1, max_size1,
1077 base2, offset2, max_size2);
1079 ind1_p = (INDIRECT_REF_P (base1)
1080 || (TREE_CODE (base1) == MEM_REF)
1081 || (TREE_CODE (base1) == TARGET_MEM_REF));
1082 ind2_p = (INDIRECT_REF_P (base2)
1083 || (TREE_CODE (base2) == MEM_REF)
1084 || (TREE_CODE (base2) == TARGET_MEM_REF));
1086 /* Canonicalize the pointer-vs-decl case. */
1087 if (ind1_p && var2_p)
1092 tmp1 = offset1; offset1 = offset2; offset2 = tmp1;
1093 tmp1 = max_size1; max_size1 = max_size2; max_size2 = tmp1;
1094 tmp2 = base1; base1 = base2; base2 = tmp2;
1095 tmp3 = ref1; ref1 = ref2; ref2 = tmp3;
1102 /* First defer to TBAA if possible. */
1104 && flag_strict_aliasing
1105 && !alias_sets_conflict_p (ao_ref_alias_set (ref1),
1106 ao_ref_alias_set (ref2)))
1109 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */
1110 if (var1_p && ind2_p)
1111 return indirect_ref_may_alias_decl_p (ref2->ref, base2,
1113 ao_ref_alias_set (ref2), -1,
1116 ao_ref_alias_set (ref1),
1117 ao_ref_base_alias_set (ref1),
1119 else if (ind1_p && ind2_p)
1120 return indirect_refs_may_alias_p (ref1->ref, base1,
1122 ao_ref_alias_set (ref1), -1,
1125 ao_ref_alias_set (ref2), -1,
1128 /* We really do not want to end up here, but returning true is safe. */
1129 #ifdef ENABLE_CHECKING
1137 refs_may_alias_p (tree ref1, tree ref2)
1141 ao_ref_init (&r1, ref1);
1142 ao_ref_init (&r2, ref2);
1143 res = refs_may_alias_p_1 (&r1, &r2, true);
1145 ++alias_stats.refs_may_alias_p_may_alias;
1147 ++alias_stats.refs_may_alias_p_no_alias;
1151 /* Returns true if there is a anti-dependence for the STORE that
1152 executes after the LOAD. */
1155 refs_anti_dependent_p (tree load, tree store)
1158 ao_ref_init (&r1, load);
1159 ao_ref_init (&r2, store);
1160 return refs_may_alias_p_1 (&r1, &r2, false);
1163 /* Returns true if there is a output dependence for the stores
1164 STORE1 and STORE2. */
1167 refs_output_dependent_p (tree store1, tree store2)
1170 ao_ref_init (&r1, store1);
1171 ao_ref_init (&r2, store2);
1172 return refs_may_alias_p_1 (&r1, &r2, false);
1175 /* If the call CALL may use the memory reference REF return true,
1176 otherwise return false. */
1179 ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
1183 int flags = gimple_call_flags (call);
1185 /* Const functions without a static chain do not implicitly use memory. */
1186 if (!gimple_call_chain (call)
1187 && (flags & (ECF_CONST|ECF_NOVOPS)))
1190 base = ao_ref_base (ref);
1194 /* If the reference is based on a decl that is not aliased the call
1195 cannot possibly use it. */
1197 && !may_be_aliased (base)
1198 /* But local statics can be used through recursion. */
1199 && !is_global_var (base))
1202 callee = gimple_call_fndecl (call);
1204 /* Handle those builtin functions explicitly that do not act as
1205 escape points. See tree-ssa-structalias.c:find_func_aliases
1206 for the list of builtins we might need to handle here. */
1207 if (callee != NULL_TREE
1208 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1209 switch (DECL_FUNCTION_CODE (callee))
1211 /* All the following functions read memory pointed to by
1212 their second argument. strcat/strncat additionally
1213 reads memory pointed to by the first argument. */
1214 case BUILT_IN_STRCAT:
1215 case BUILT_IN_STRNCAT:
1218 ao_ref_init_from_ptr_and_size (&dref,
1219 gimple_call_arg (call, 0),
1221 if (refs_may_alias_p_1 (&dref, ref, false))
1225 case BUILT_IN_STRCPY:
1226 case BUILT_IN_STRNCPY:
1227 case BUILT_IN_MEMCPY:
1228 case BUILT_IN_MEMMOVE:
1229 case BUILT_IN_MEMPCPY:
1230 case BUILT_IN_STPCPY:
1231 case BUILT_IN_STPNCPY:
1234 tree size = NULL_TREE;
1235 if (gimple_call_num_args (call) == 3)
1236 size = gimple_call_arg (call, 2);
1237 ao_ref_init_from_ptr_and_size (&dref,
1238 gimple_call_arg (call, 1),
1240 return refs_may_alias_p_1 (&dref, ref, false);
1242 case BUILT_IN_BCOPY:
1245 tree size = gimple_call_arg (call, 2);
1246 ao_ref_init_from_ptr_and_size (&dref,
1247 gimple_call_arg (call, 0),
1249 return refs_may_alias_p_1 (&dref, ref, false);
1251 /* The following builtins do not read from memory. */
1253 case BUILT_IN_MALLOC:
1254 case BUILT_IN_CALLOC:
1255 case BUILT_IN_MEMSET:
1256 case BUILT_IN_FREXP:
1257 case BUILT_IN_FREXPF:
1258 case BUILT_IN_FREXPL:
1259 case BUILT_IN_GAMMA_R:
1260 case BUILT_IN_GAMMAF_R:
1261 case BUILT_IN_GAMMAL_R:
1262 case BUILT_IN_LGAMMA_R:
1263 case BUILT_IN_LGAMMAF_R:
1264 case BUILT_IN_LGAMMAL_R:
1266 case BUILT_IN_MODFF:
1267 case BUILT_IN_MODFL:
1268 case BUILT_IN_REMQUO:
1269 case BUILT_IN_REMQUOF:
1270 case BUILT_IN_REMQUOL:
1271 case BUILT_IN_SINCOS:
1272 case BUILT_IN_SINCOSF:
1273 case BUILT_IN_SINCOSL:
1275 /* __sync_* builtins and some OpenMP builtins act as threading
1277 #undef DEF_SYNC_BUILTIN
1278 #define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM:
1279 #include "sync-builtins.def"
1280 #undef DEF_SYNC_BUILTIN
1281 case BUILT_IN_GOMP_ATOMIC_START:
1282 case BUILT_IN_GOMP_ATOMIC_END:
1283 case BUILT_IN_GOMP_BARRIER:
1284 case BUILT_IN_GOMP_TASKWAIT:
1285 case BUILT_IN_GOMP_CRITICAL_START:
1286 case BUILT_IN_GOMP_CRITICAL_END:
1287 case BUILT_IN_GOMP_CRITICAL_NAME_START:
1288 case BUILT_IN_GOMP_CRITICAL_NAME_END:
1289 case BUILT_IN_GOMP_LOOP_END:
1290 case BUILT_IN_GOMP_ORDERED_START:
1291 case BUILT_IN_GOMP_ORDERED_END:
1292 case BUILT_IN_GOMP_PARALLEL_END:
1293 case BUILT_IN_GOMP_SECTIONS_END:
1294 case BUILT_IN_GOMP_SINGLE_COPY_START:
1295 case BUILT_IN_GOMP_SINGLE_COPY_END:
1299 /* Fallthru to general call handling. */;
1302 /* Check if base is a global static variable that is not read
1304 if (TREE_CODE (base) == VAR_DECL
1305 && TREE_STATIC (base))
1309 if (callee != NULL_TREE
1311 = ipa_reference_get_not_read_global (cgraph_node (callee)))
1312 && bitmap_bit_p (not_read, DECL_UID (base)))
1316 /* Check if the base variable is call-used. */
1319 if (pt_solution_includes (gimple_call_use_set (call), base))
1322 else if ((INDIRECT_REF_P (base)
1323 || TREE_CODE (base) == MEM_REF)
1324 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1326 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1330 if (pt_solutions_intersect (gimple_call_use_set (call), &pi->pt))
1336 /* Inspect call arguments for passed-by-value aliases. */
1338 for (i = 0; i < gimple_call_num_args (call); ++i)
1340 tree op = gimple_call_arg (call, i);
1341 int flags = gimple_call_arg_flags (call, i);
1343 if (flags & EAF_UNUSED)
1346 if (TREE_CODE (op) == WITH_SIZE_EXPR)
1347 op = TREE_OPERAND (op, 0);
1349 if (TREE_CODE (op) != SSA_NAME
1350 && !is_gimple_min_invariant (op))
1353 ao_ref_init (&r, op);
1354 if (refs_may_alias_p_1 (&r, ref, true))
1363 ref_maybe_used_by_call_p (gimple call, tree ref)
1367 ao_ref_init (&r, ref);
1368 res = ref_maybe_used_by_call_p_1 (call, &r);
1370 ++alias_stats.ref_maybe_used_by_call_p_may_alias;
1372 ++alias_stats.ref_maybe_used_by_call_p_no_alias;
1377 /* If the statement STMT may use the memory reference REF return
1378 true, otherwise return false. */
1381 ref_maybe_used_by_stmt_p (gimple stmt, tree ref)
1383 if (is_gimple_assign (stmt))
1387 /* All memory assign statements are single. */
1388 if (!gimple_assign_single_p (stmt))
1391 rhs = gimple_assign_rhs1 (stmt);
1392 if (is_gimple_reg (rhs)
1393 || is_gimple_min_invariant (rhs)
1394 || gimple_assign_rhs_code (stmt) == CONSTRUCTOR)
1397 return refs_may_alias_p (rhs, ref);
1399 else if (is_gimple_call (stmt))
1400 return ref_maybe_used_by_call_p (stmt, ref);
1405 /* If the call in statement CALL may clobber the memory reference REF
1406 return true, otherwise return false. */
1409 call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
1414 /* If the call is pure or const it cannot clobber anything. */
1415 if (gimple_call_flags (call)
1416 & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS))
1419 base = ao_ref_base (ref);
1423 if (TREE_CODE (base) == SSA_NAME
1424 || CONSTANT_CLASS_P (base))
1427 /* If the reference is based on a decl that is not aliased the call
1428 cannot possibly clobber it. */
1430 && !may_be_aliased (base)
1431 /* But local non-readonly statics can be modified through recursion
1432 or the call may implement a threading barrier which we must
1433 treat as may-def. */
1434 && (TREE_READONLY (base)
1435 || !is_global_var (base)))
1438 callee = gimple_call_fndecl (call);
1440 /* Handle those builtin functions explicitly that do not act as
1441 escape points. See tree-ssa-structalias.c:find_func_aliases
1442 for the list of builtins we might need to handle here. */
1443 if (callee != NULL_TREE
1444 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
1445 switch (DECL_FUNCTION_CODE (callee))
1447 /* All the following functions clobber memory pointed to by
1448 their first argument. */
1449 case BUILT_IN_STRCPY:
1450 case BUILT_IN_STRNCPY:
1451 case BUILT_IN_MEMCPY:
1452 case BUILT_IN_MEMMOVE:
1453 case BUILT_IN_MEMPCPY:
1454 case BUILT_IN_STPCPY:
1455 case BUILT_IN_STPNCPY:
1456 case BUILT_IN_STRCAT:
1457 case BUILT_IN_STRNCAT:
1458 case BUILT_IN_MEMSET:
1461 tree size = NULL_TREE;
1462 /* Don't pass in size for strncat, as the maximum size
1463 is strlen (dest) + n + 1 instead of n, resp.
1464 n + 1 at dest + strlen (dest), but strlen (dest) isn't
1466 if (gimple_call_num_args (call) == 3
1467 && DECL_FUNCTION_CODE (callee) != BUILT_IN_STRNCAT)
1468 size = gimple_call_arg (call, 2);
1469 ao_ref_init_from_ptr_and_size (&dref,
1470 gimple_call_arg (call, 0),
1472 return refs_may_alias_p_1 (&dref, ref, false);
1474 case BUILT_IN_BCOPY:
1477 tree size = gimple_call_arg (call, 2);
1478 ao_ref_init_from_ptr_and_size (&dref,
1479 gimple_call_arg (call, 1),
1481 return refs_may_alias_p_1 (&dref, ref, false);
1483 /* Allocating memory does not have any side-effects apart from
1484 being the definition point for the pointer. */
1485 case BUILT_IN_MALLOC:
1486 case BUILT_IN_CALLOC:
1487 /* Unix98 specifies that errno is set on allocation failure. */
1489 && targetm.ref_may_alias_errno (ref))
1492 /* Freeing memory kills the pointed-to memory. More importantly
1493 the call has to serve as a barrier for moving loads and stores
1497 tree ptr = gimple_call_arg (call, 0);
1498 return ptr_deref_may_alias_ref_p_1 (ptr, ref);
1500 case BUILT_IN_GAMMA_R:
1501 case BUILT_IN_GAMMAF_R:
1502 case BUILT_IN_GAMMAL_R:
1503 case BUILT_IN_LGAMMA_R:
1504 case BUILT_IN_LGAMMAF_R:
1505 case BUILT_IN_LGAMMAL_R:
1507 tree out = gimple_call_arg (call, 1);
1508 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1510 if (flag_errno_math)
1514 case BUILT_IN_FREXP:
1515 case BUILT_IN_FREXPF:
1516 case BUILT_IN_FREXPL:
1518 case BUILT_IN_MODFF:
1519 case BUILT_IN_MODFL:
1521 tree out = gimple_call_arg (call, 1);
1522 return ptr_deref_may_alias_ref_p_1 (out, ref);
1524 case BUILT_IN_REMQUO:
1525 case BUILT_IN_REMQUOF:
1526 case BUILT_IN_REMQUOL:
1528 tree out = gimple_call_arg (call, 2);
1529 if (ptr_deref_may_alias_ref_p_1 (out, ref))
1531 if (flag_errno_math)
1535 case BUILT_IN_SINCOS:
1536 case BUILT_IN_SINCOSF:
1537 case BUILT_IN_SINCOSL:
1539 tree sin = gimple_call_arg (call, 1);
1540 tree cos = gimple_call_arg (call, 2);
1541 return (ptr_deref_may_alias_ref_p_1 (sin, ref)
1542 || ptr_deref_may_alias_ref_p_1 (cos, ref));
1544 /* __sync_* builtins and some OpenMP builtins act as threading
1546 #undef DEF_SYNC_BUILTIN
1547 #define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM:
1548 #include "sync-builtins.def"
1549 #undef DEF_SYNC_BUILTIN
1550 case BUILT_IN_GOMP_ATOMIC_START:
1551 case BUILT_IN_GOMP_ATOMIC_END:
1552 case BUILT_IN_GOMP_BARRIER:
1553 case BUILT_IN_GOMP_TASKWAIT:
1554 case BUILT_IN_GOMP_CRITICAL_START:
1555 case BUILT_IN_GOMP_CRITICAL_END:
1556 case BUILT_IN_GOMP_CRITICAL_NAME_START:
1557 case BUILT_IN_GOMP_CRITICAL_NAME_END:
1558 case BUILT_IN_GOMP_LOOP_END:
1559 case BUILT_IN_GOMP_ORDERED_START:
1560 case BUILT_IN_GOMP_ORDERED_END:
1561 case BUILT_IN_GOMP_PARALLEL_END:
1562 case BUILT_IN_GOMP_SECTIONS_END:
1563 case BUILT_IN_GOMP_SINGLE_COPY_START:
1564 case BUILT_IN_GOMP_SINGLE_COPY_END:
1567 /* Fallthru to general call handling. */;
1570 /* Check if base is a global static variable that is not written
1572 if (callee != NULL_TREE
1573 && TREE_CODE (base) == VAR_DECL
1574 && TREE_STATIC (base))
1579 = ipa_reference_get_not_written_global (cgraph_node (callee)))
1580 && bitmap_bit_p (not_written, DECL_UID (base)))
1584 /* Check if the base variable is call-clobbered. */
1586 return pt_solution_includes (gimple_call_clobber_set (call), base);
1587 else if ((INDIRECT_REF_P (base)
1588 || TREE_CODE (base) == MEM_REF)
1589 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1591 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1595 return pt_solutions_intersect (gimple_call_clobber_set (call), &pi->pt);
1601 /* If the call in statement CALL may clobber the memory reference REF
1602 return true, otherwise return false. */
1605 call_may_clobber_ref_p (gimple call, tree ref)
1609 ao_ref_init (&r, ref);
1610 res = call_may_clobber_ref_p_1 (call, &r);
1612 ++alias_stats.call_may_clobber_ref_p_may_alias;
1614 ++alias_stats.call_may_clobber_ref_p_no_alias;
1619 /* If the statement STMT may clobber the memory reference REF return true,
1620 otherwise return false. */
1623 stmt_may_clobber_ref_p_1 (gimple stmt, ao_ref *ref)
1625 if (is_gimple_call (stmt))
1627 tree lhs = gimple_call_lhs (stmt);
1629 && TREE_CODE (lhs) != SSA_NAME)
1632 ao_ref_init (&r, lhs);
1633 if (refs_may_alias_p_1 (ref, &r, true))
1637 return call_may_clobber_ref_p_1 (stmt, ref);
1639 else if (gimple_assign_single_p (stmt))
1641 tree lhs = gimple_assign_lhs (stmt);
1642 if (TREE_CODE (lhs) != SSA_NAME)
1645 ao_ref_init (&r, lhs);
1646 return refs_may_alias_p_1 (ref, &r, true);
1649 else if (gimple_code (stmt) == GIMPLE_ASM)
1656 stmt_may_clobber_ref_p (gimple stmt, tree ref)
1659 ao_ref_init (&r, ref);
1660 return stmt_may_clobber_ref_p_1 (stmt, &r);
1663 /* If STMT kills the memory reference REF return true, otherwise
1667 stmt_kills_ref_p_1 (gimple stmt, ao_ref *ref)
1669 if (gimple_has_lhs (stmt)
1670 && TREE_CODE (gimple_get_lhs (stmt)) != SSA_NAME
1671 /* The assignment is not necessarily carried out if it can throw
1672 and we can catch it in the current function where we could inspect
1674 ??? We only need to care about the RHS throwing. For aggregate
1675 assignments or similar calls and non-call exceptions the LHS
1676 might throw as well. */
1677 && !stmt_can_throw_internal (stmt))
1679 tree base, lhs = gimple_get_lhs (stmt);
1680 HOST_WIDE_INT size, offset, max_size;
1682 base = get_ref_base_and_extent (lhs, &offset, &size, &max_size);
1683 /* We can get MEM[symbol: sZ, index: D.8862_1] here,
1684 so base == ref->base does not always hold. */
1685 if (base == ref->base)
1687 /* For a must-alias check we need to be able to constrain
1688 the accesses properly. */
1689 if (size != -1 && size == max_size
1690 && ref->max_size != -1)
1692 if (offset <= ref->offset
1693 && offset + size >= ref->offset + ref->max_size)
1702 stmt_kills_ref_p (gimple stmt, tree ref)
1705 ao_ref_init (&r, ref);
1706 return stmt_kills_ref_p_1 (stmt, &r);
1710 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand
1711 TARGET or a statement clobbering the memory reference REF in which
1712 case false is returned. The walk starts with VUSE, one argument of PHI. */
1715 maybe_skip_until (gimple phi, tree target, ao_ref *ref,
1716 tree vuse, bitmap *visited)
1719 *visited = BITMAP_ALLOC (NULL);
1721 bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi)));
1723 /* Walk until we hit the target. */
1724 while (vuse != target)
1726 gimple def_stmt = SSA_NAME_DEF_STMT (vuse);
1727 /* Recurse for PHI nodes. */
1728 if (gimple_code (def_stmt) == GIMPLE_PHI)
1730 /* An already visited PHI node ends the walk successfully. */
1731 if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt))))
1733 vuse = get_continuation_for_phi (def_stmt, ref, visited);
1738 /* A clobbering statement or the end of the IL ends it failing. */
1739 else if (gimple_nop_p (def_stmt)
1740 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1742 vuse = gimple_vuse (def_stmt);
1747 /* Starting from a PHI node for the virtual operand of the memory reference
1748 REF find a continuation virtual operand that allows to continue walking
1749 statements dominating PHI skipping only statements that cannot possibly
1750 clobber REF. Returns NULL_TREE if no suitable virtual operand can
1754 get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited)
1756 unsigned nargs = gimple_phi_num_args (phi);
1758 /* Through a single-argument PHI we can simply look through. */
1760 return PHI_ARG_DEF (phi, 0);
1762 /* For two arguments try to skip non-aliasing code until we hit
1763 the phi argument definition that dominates the other one. */
1766 tree arg0 = PHI_ARG_DEF (phi, 0);
1767 tree arg1 = PHI_ARG_DEF (phi, 1);
1768 gimple def0 = SSA_NAME_DEF_STMT (arg0);
1769 gimple def1 = SSA_NAME_DEF_STMT (arg1);
1774 else if (gimple_nop_p (def0)
1775 || (!gimple_nop_p (def1)
1776 && dominated_by_p (CDI_DOMINATORS,
1777 gimple_bb (def1), gimple_bb (def0))))
1779 if (maybe_skip_until (phi, arg0, ref, arg1, visited))
1782 else if (gimple_nop_p (def1)
1783 || dominated_by_p (CDI_DOMINATORS,
1784 gimple_bb (def0), gimple_bb (def1)))
1786 if (maybe_skip_until (phi, arg1, ref, arg0, visited))
1789 /* Special case of a diamond:
1791 goto (cond) ? L1 : L2
1792 L1: store1 = ... #MEM_2 = vuse(MEM_1)
1794 L2: store2 = ... #MEM_3 = vuse(MEM_1)
1795 L3: MEM_4 = PHI<MEM_2, MEM_3>
1796 We were called with the PHI at L3, MEM_2 and MEM_3 don't
1797 dominate each other, but still we can easily skip this PHI node
1798 if we recognize that the vuse MEM operand is the same for both,
1799 and that we can skip both statements (they don't clobber us).
1800 This is still linear. Don't use maybe_skip_until, that might
1801 potentially be slow. */
1802 else if ((common_vuse = gimple_vuse (def0))
1803 && common_vuse == gimple_vuse (def1))
1805 if (!stmt_may_clobber_ref_p_1 (def0, ref)
1806 && !stmt_may_clobber_ref_p_1 (def1, ref))
1814 /* Based on the memory reference REF and its virtual use VUSE call
1815 WALKER for each virtual use that is equivalent to VUSE, including VUSE
1816 itself. That is, for each virtual use for which its defining statement
1817 does not clobber REF.
1819 WALKER is called with REF, the current virtual use and DATA. If
1820 WALKER returns non-NULL the walk stops and its result is returned.
1821 At the end of a non-successful walk NULL is returned.
1823 TRANSLATE if non-NULL is called with a pointer to REF, the virtual
1824 use which definition is a statement that may clobber REF and DATA.
1825 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
1826 If TRANSLATE returns non-NULL the walk stops and its result is returned.
1827 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
1828 to adjust REF and *DATA to make that valid.
1830 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
1833 walk_non_aliased_vuses (ao_ref *ref, tree vuse,
1834 void *(*walker)(ao_ref *, tree, void *),
1835 void *(*translate)(ao_ref *, tree, void *), void *data)
1837 bitmap visited = NULL;
1840 timevar_push (TV_ALIAS_STMT_WALK);
1846 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1847 res = (*walker) (ref, vuse, data);
1851 def_stmt = SSA_NAME_DEF_STMT (vuse);
1852 if (gimple_nop_p (def_stmt))
1854 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1855 vuse = get_continuation_for_phi (def_stmt, ref, &visited);
1858 if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
1862 res = (*translate) (ref, vuse, data);
1863 /* Failed lookup and translation. */
1864 if (res == (void *)-1)
1869 /* Lookup succeeded. */
1870 else if (res != NULL)
1872 /* Translation succeeded, continue walking. */
1874 vuse = gimple_vuse (def_stmt);
1880 BITMAP_FREE (visited);
1882 timevar_pop (TV_ALIAS_STMT_WALK);
1888 /* Based on the memory reference REF call WALKER for each vdef which
1889 defining statement may clobber REF, starting with VDEF. If REF
1890 is NULL_TREE, each defining statement is visited.
1892 WALKER is called with REF, the current vdef and DATA. If WALKER
1893 returns true the walk is stopped, otherwise it continues.
1895 At PHI nodes walk_aliased_vdefs forks into one walk for reach
1896 PHI argument (but only one walk continues on merge points), the
1897 return value is true if any of the walks was successful.
1899 The function returns the number of statements walked. */
1902 walk_aliased_vdefs_1 (ao_ref *ref, tree vdef,
1903 bool (*walker)(ao_ref *, tree, void *), void *data,
1904 bitmap *visited, unsigned int cnt)
1908 gimple def_stmt = SSA_NAME_DEF_STMT (vdef);
1911 && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef)))
1914 if (gimple_nop_p (def_stmt))
1916 else if (gimple_code (def_stmt) == GIMPLE_PHI)
1920 *visited = BITMAP_ALLOC (NULL);
1921 for (i = 0; i < gimple_phi_num_args (def_stmt); ++i)
1922 cnt += walk_aliased_vdefs_1 (ref, gimple_phi_arg_def (def_stmt, i),
1923 walker, data, visited, 0);
1927 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1930 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
1931 && (*walker) (ref, vdef, data))
1934 vdef = gimple_vuse (def_stmt);
1940 walk_aliased_vdefs (ao_ref *ref, tree vdef,
1941 bool (*walker)(ao_ref *, tree, void *), void *data,
1944 bitmap local_visited = NULL;
1947 timevar_push (TV_ALIAS_STMT_WALK);
1949 ret = walk_aliased_vdefs_1 (ref, vdef, walker, data,
1950 visited ? visited : &local_visited, 0);
1952 BITMAP_FREE (local_visited);
1954 timevar_pop (TV_ALIAS_STMT_WALK);