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 "hard-reg-set.h"
30 #include "basic-block.h"
34 #include "langhooks.h"
37 #include "diagnostic.h"
38 #include "tree-dump.h"
40 #include "tree-flow.h"
41 #include "tree-inline.h"
42 #include "tree-pass.h"
45 #include "ipa-type-escape.h"
49 #include "pointer-set.h"
50 #include "alloc-pool.h"
51 #include "tree-ssa-alias.h"
53 /* Broad overview of how alias analysis on gimple works:
55 Statements clobbering or using memory are linked through the
56 virtual operand factored use-def chain. The virtual operand
57 is unique per function, its symbol is accessible via gimple_vop (cfun).
58 Virtual operands are used for efficiently walking memory statements
59 in the gimple IL and are useful for things like value-numbering as
60 a generation count for memory references.
62 SSA_NAME pointers may have associated points-to information
63 accessible via the SSA_NAME_PTR_INFO macro. Flow-insensitive
64 points-to information is (re-)computed by the TODO_rebuild_alias
65 pass manager todo. Points-to information is also used for more
66 precise tracking of call-clobbered and call-used variables and
67 related disambiguations.
69 This file contains functions for disambiguating memory references,
70 the so called alias-oracle and tools for walking of the gimple IL.
72 The main alias-oracle entry-points are
74 bool stmt_may_clobber_ref_p (gimple, tree)
76 This function queries if a statement may invalidate (parts of)
77 the memory designated by the reference tree argument.
79 bool ref_maybe_used_by_stmt_p (gimple, tree)
81 This function queries if a statement may need (parts of) the
82 memory designated by the reference tree argument.
84 There are variants of these functions that only handle the call
85 part of a statement, call_may_clobber_ref_p and ref_maybe_used_by_call_p.
86 Note that these do not disambiguate against a possible call lhs.
88 bool refs_may_alias_p (tree, tree)
90 This function tries to disambiguate two reference trees.
92 bool ptr_deref_may_alias_global_p (tree)
94 This function queries if dereferencing a pointer variable may
97 More low-level disambiguators are available and documented in
98 this file. Low-level disambiguators dealing with points-to
99 information are in tree-ssa-structalias.c. */
102 /* Query statistics for the different low-level disambiguators.
103 A high-level query may trigger multiple of them. */
106 unsigned HOST_WIDE_INT refs_may_alias_p_may_alias
;
107 unsigned HOST_WIDE_INT refs_may_alias_p_no_alias
;
108 unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_may_alias
;
109 unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_no_alias
;
110 unsigned HOST_WIDE_INT call_may_clobber_ref_p_may_alias
;
111 unsigned HOST_WIDE_INT call_may_clobber_ref_p_no_alias
;
115 dump_alias_stats (FILE *s
)
117 fprintf (s
, "\nAlias oracle query stats:\n");
118 fprintf (s
, " refs_may_alias_p: "
119 HOST_WIDE_INT_PRINT_DEC
" disambiguations, "
120 HOST_WIDE_INT_PRINT_DEC
" queries\n",
121 alias_stats
.refs_may_alias_p_no_alias
,
122 alias_stats
.refs_may_alias_p_no_alias
123 + alias_stats
.refs_may_alias_p_may_alias
);
124 fprintf (s
, " ref_maybe_used_by_call_p: "
125 HOST_WIDE_INT_PRINT_DEC
" disambiguations, "
126 HOST_WIDE_INT_PRINT_DEC
" queries\n",
127 alias_stats
.ref_maybe_used_by_call_p_no_alias
,
128 alias_stats
.refs_may_alias_p_no_alias
129 + alias_stats
.ref_maybe_used_by_call_p_may_alias
);
130 fprintf (s
, " call_may_clobber_ref_p: "
131 HOST_WIDE_INT_PRINT_DEC
" disambiguations, "
132 HOST_WIDE_INT_PRINT_DEC
" queries\n",
133 alias_stats
.call_may_clobber_ref_p_no_alias
,
134 alias_stats
.call_may_clobber_ref_p_no_alias
135 + alias_stats
.call_may_clobber_ref_p_may_alias
);
139 /* Return true, if dereferencing PTR may alias with a global variable. */
142 ptr_deref_may_alias_global_p (tree ptr
)
144 struct ptr_info_def
*pi
;
146 /* If we end up with a pointer constant here that may point
148 if (TREE_CODE (ptr
) != SSA_NAME
)
151 pi
= SSA_NAME_PTR_INFO (ptr
);
153 /* If we do not have points-to information for this variable,
158 /* ??? This does not use TBAA to prune globals ptr may not access. */
159 return pt_solution_includes_global (&pi
->pt
);
162 /* Return true if dereferencing PTR may alias DECL.
163 The caller is responsible for applying TBAA to see if PTR
164 may access DECL at all. */
167 ptr_deref_may_alias_decl_p (tree ptr
, tree decl
)
169 struct ptr_info_def
*pi
;
171 gcc_assert ((TREE_CODE (ptr
) == SSA_NAME
172 || TREE_CODE (ptr
) == ADDR_EXPR
173 || TREE_CODE (ptr
) == INTEGER_CST
)
174 && (TREE_CODE (decl
) == VAR_DECL
175 || TREE_CODE (decl
) == PARM_DECL
176 || TREE_CODE (decl
) == RESULT_DECL
));
178 /* Non-aliased variables can not be pointed to. */
179 if (!may_be_aliased (decl
))
182 /* ADDR_EXPR pointers either just offset another pointer or directly
183 specify the pointed-to set. */
184 if (TREE_CODE (ptr
) == ADDR_EXPR
)
186 tree base
= get_base_address (TREE_OPERAND (ptr
, 0));
188 && INDIRECT_REF_P (base
))
189 ptr
= TREE_OPERAND (base
, 0);
192 return operand_equal_p (base
, decl
, 0);
194 && CONSTANT_CLASS_P (base
))
200 /* We can end up with dereferencing constant pointers.
201 Just bail out in this case. */
202 if (TREE_CODE (ptr
) == INTEGER_CST
)
205 /* If we do not have useful points-to information for this pointer
206 we cannot disambiguate anything else. */
207 pi
= SSA_NAME_PTR_INFO (ptr
);
211 /* If the decl can be used as a restrict tag and we have a restrict
212 pointer and that pointers points-to set doesn't contain this decl
213 then they can't alias. */
214 if (DECL_RESTRICTED_P (decl
)
215 && TYPE_RESTRICT (TREE_TYPE (ptr
))
216 && pi
->pt
.vars_contains_restrict
)
217 return bitmap_bit_p (pi
->pt
.vars
, DECL_UID (decl
));
219 return pt_solution_includes (&pi
->pt
, decl
);
222 /* Return true if dereferenced PTR1 and PTR2 may alias.
223 The caller is responsible for applying TBAA to see if accesses
224 through PTR1 and PTR2 may conflict at all. */
227 ptr_derefs_may_alias_p (tree ptr1
, tree ptr2
)
229 struct ptr_info_def
*pi1
, *pi2
;
231 gcc_assert ((TREE_CODE (ptr1
) == SSA_NAME
232 || TREE_CODE (ptr1
) == ADDR_EXPR
233 || TREE_CODE (ptr1
) == INTEGER_CST
)
234 && (TREE_CODE (ptr2
) == SSA_NAME
235 || TREE_CODE (ptr2
) == ADDR_EXPR
236 || TREE_CODE (ptr2
) == INTEGER_CST
));
238 /* ADDR_EXPR pointers either just offset another pointer or directly
239 specify the pointed-to set. */
240 if (TREE_CODE (ptr1
) == ADDR_EXPR
)
242 tree base
= get_base_address (TREE_OPERAND (ptr1
, 0));
244 && INDIRECT_REF_P (base
))
245 ptr1
= TREE_OPERAND (base
, 0);
248 return ptr_deref_may_alias_decl_p (ptr2
, base
);
252 if (TREE_CODE (ptr2
) == ADDR_EXPR
)
254 tree base
= get_base_address (TREE_OPERAND (ptr2
, 0));
256 && INDIRECT_REF_P (base
))
257 ptr2
= TREE_OPERAND (base
, 0);
260 return ptr_deref_may_alias_decl_p (ptr1
, base
);
265 /* We can end up with dereferencing constant pointers.
266 Just bail out in this case. */
267 if (TREE_CODE (ptr1
) == INTEGER_CST
268 || TREE_CODE (ptr2
) == INTEGER_CST
)
271 /* We may end up with two empty points-to solutions for two same pointers.
272 In this case we still want to say both pointers alias, so shortcut
277 /* If we do not have useful points-to information for either pointer
278 we cannot disambiguate anything else. */
279 pi1
= SSA_NAME_PTR_INFO (ptr1
);
280 pi2
= SSA_NAME_PTR_INFO (ptr2
);
284 /* If both pointers are restrict-qualified try to disambiguate
285 with restrict information. */
286 if (TYPE_RESTRICT (TREE_TYPE (ptr1
))
287 && TYPE_RESTRICT (TREE_TYPE (ptr2
))
288 && !pt_solutions_same_restrict_base (&pi1
->pt
, &pi2
->pt
))
291 /* ??? This does not use TBAA to prune decls from the intersection
292 that not both pointers may access. */
293 return pt_solutions_intersect (&pi1
->pt
, &pi2
->pt
);
296 /* Return true if dereferencing PTR may alias *REF.
297 The caller is responsible for applying TBAA to see if PTR
298 may access *REF at all. */
301 ptr_deref_may_alias_ref_p_1 (tree ptr
, ao_ref
*ref
)
303 tree base
= ao_ref_base (ref
);
305 if (INDIRECT_REF_P (base
))
306 return ptr_derefs_may_alias_p (ptr
, TREE_OPERAND (base
, 0));
307 else if (SSA_VAR_P (base
))
308 return ptr_deref_may_alias_decl_p (ptr
, base
);
314 /* Dump alias information on FILE. */
317 dump_alias_info (FILE *file
)
321 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
322 referenced_var_iterator rvi
;
325 fprintf (file
, "\n\nAlias information for %s\n\n", funcname
);
327 fprintf (file
, "Aliased symbols\n\n");
329 FOR_EACH_REFERENCED_VAR (var
, rvi
)
331 if (may_be_aliased (var
))
332 dump_variable (file
, var
);
335 fprintf (file
, "\nCall clobber information\n");
337 fprintf (file
, "\nESCAPED");
338 dump_points_to_solution (file
, &cfun
->gimple_df
->escaped
);
339 fprintf (file
, "\nCALLUSED");
340 dump_points_to_solution (file
, &cfun
->gimple_df
->callused
);
342 fprintf (file
, "\n\nFlow-insensitive points-to information\n\n");
344 for (i
= 1; i
< num_ssa_names
; i
++)
346 tree ptr
= ssa_name (i
);
347 struct ptr_info_def
*pi
;
350 || SSA_NAME_IN_FREE_LIST (ptr
))
353 pi
= SSA_NAME_PTR_INFO (ptr
);
355 dump_points_to_info_for (file
, ptr
);
358 fprintf (file
, "\n");
362 /* Dump alias information on stderr. */
365 debug_alias_info (void)
367 dump_alias_info (stderr
);
371 /* Return the alias information associated with pointer T. It creates a
372 new instance if none existed. */
374 struct ptr_info_def
*
375 get_ptr_info (tree t
)
377 struct ptr_info_def
*pi
;
379 gcc_assert (POINTER_TYPE_P (TREE_TYPE (t
)));
381 pi
= SSA_NAME_PTR_INFO (t
);
384 pi
= GGC_CNEW (struct ptr_info_def
);
385 pt_solution_reset (&pi
->pt
);
386 SSA_NAME_PTR_INFO (t
) = pi
;
392 /* Dump the points-to set *PT into FILE. */
395 dump_points_to_solution (FILE *file
, struct pt_solution
*pt
)
398 fprintf (file
, ", points-to anything");
401 fprintf (file
, ", points-to non-local");
404 fprintf (file
, ", points-to escaped");
407 fprintf (file
, ", points-to NULL");
411 fprintf (file
, ", points-to vars: ");
412 dump_decl_set (file
, pt
->vars
);
413 if (pt
->vars_contains_global
)
414 fprintf (file
, " (includes global vars)");
418 /* Dump points-to information for SSA_NAME PTR into FILE. */
421 dump_points_to_info_for (FILE *file
, tree ptr
)
423 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (ptr
);
425 print_generic_expr (file
, ptr
, dump_flags
);
428 dump_points_to_solution (file
, &pi
->pt
);
430 fprintf (file
, ", points-to anything");
432 fprintf (file
, "\n");
436 /* Dump points-to information for VAR into stderr. */
439 debug_points_to_info_for (tree var
)
441 dump_points_to_info_for (stderr
, var
);
445 /* Initializes the alias-oracle reference representation *R from REF. */
448 ao_ref_init (ao_ref
*r
, tree ref
)
455 r
->ref_alias_set
= -1;
456 r
->base_alias_set
= -1;
459 /* Returns the base object of the memory reference *REF. */
462 ao_ref_base (ao_ref
*ref
)
466 ref
->base
= get_ref_base_and_extent (ref
->ref
, &ref
->offset
, &ref
->size
,
471 /* Returns the base object alias set of the memory reference *REF. */
473 static alias_set_type ATTRIBUTE_UNUSED
474 ao_ref_base_alias_set (ao_ref
*ref
)
476 if (ref
->base_alias_set
!= -1)
477 return ref
->base_alias_set
;
478 ref
->base_alias_set
= get_alias_set (ao_ref_base (ref
));
479 return ref
->base_alias_set
;
482 /* Returns the reference alias set of the memory reference *REF. */
485 ao_ref_alias_set (ao_ref
*ref
)
487 if (ref
->ref_alias_set
!= -1)
488 return ref
->ref_alias_set
;
489 ref
->ref_alias_set
= get_alias_set (ref
->ref
);
490 return ref
->ref_alias_set
;
493 /* Init an alias-oracle reference representation from a gimple pointer
494 PTR and a gimple size SIZE in bytes. If SIZE is NULL_TREE the the
495 size is assumed to be unknown. The access is assumed to be only
496 to or after of the pointer target, not before it. */
499 ao_ref_init_from_ptr_and_size (ao_ref
*ref
, tree ptr
, tree size
)
501 HOST_WIDE_INT t1
, t2
;
502 ref
->ref
= NULL_TREE
;
503 if (TREE_CODE (ptr
) == ADDR_EXPR
)
504 ref
->base
= get_ref_base_and_extent (TREE_OPERAND (ptr
, 0),
505 &ref
->offset
, &t1
, &t2
);
508 ref
->base
= build1 (INDIRECT_REF
, char_type_node
, ptr
);
512 && host_integerp (size
, 0)
513 && TREE_INT_CST_LOW (size
) * 8 / 8 == TREE_INT_CST_LOW (size
))
514 ref
->max_size
= ref
->size
= TREE_INT_CST_LOW (size
) * 8;
516 ref
->max_size
= ref
->size
= -1;
517 ref
->ref_alias_set
= 0;
518 ref
->base_alias_set
= 0;
521 /* Return 1 if TYPE1 and TYPE2 are to be considered equivalent for the
522 purpose of TBAA. Return 0 if they are distinct and -1 if we cannot
526 same_type_for_tbaa (tree type1
, tree type2
)
528 type1
= TYPE_MAIN_VARIANT (type1
);
529 type2
= TYPE_MAIN_VARIANT (type2
);
531 /* If we would have to do structural comparison bail out. */
532 if (TYPE_STRUCTURAL_EQUALITY_P (type1
)
533 || TYPE_STRUCTURAL_EQUALITY_P (type2
))
536 /* Compare the canonical types. */
537 if (TYPE_CANONICAL (type1
) == TYPE_CANONICAL (type2
))
540 /* ??? Array types are not properly unified in all cases as we have
541 spurious changes in the index types for example. Removing this
542 causes all sorts of problems with the Fortran frontend. */
543 if (TREE_CODE (type1
) == ARRAY_TYPE
544 && TREE_CODE (type2
) == ARRAY_TYPE
)
547 /* ??? In Ada, an lvalue of an unconstrained type can be used to access an
548 object of one of its constrained subtypes, e.g. when a function with an
549 unconstrained parameter passed by reference is called on an object and
550 inlined. But, even in the case of a fixed size, type and subtypes are
551 not equivalent enough as to share the same TYPE_CANONICAL, since this
552 would mean that conversions between them are useless, whereas they are
553 not (e.g. type and subtypes can have different modes). So, in the end,
554 they are only guaranteed to have the same alias set. */
555 if (get_alias_set (type1
) == get_alias_set (type2
))
558 /* The types are known to be not equal. */
562 /* Determine if the two component references REF1 and REF2 which are
563 based on access types TYPE1 and TYPE2 and of which at least one is based
564 on an indirect reference may alias. REF2 is the only one that can
565 be a decl in which case REF2_IS_DECL is true.
566 REF1_ALIAS_SET, BASE1_ALIAS_SET, REF2_ALIAS_SET and BASE2_ALIAS_SET
567 are the respective alias sets. */
570 aliasing_component_refs_p (tree ref1
, tree type1
,
571 alias_set_type ref1_alias_set
,
572 alias_set_type base1_alias_set
,
573 HOST_WIDE_INT offset1
, HOST_WIDE_INT max_size1
,
574 tree ref2
, tree type2
,
575 alias_set_type ref2_alias_set
,
576 alias_set_type base2_alias_set
,
577 HOST_WIDE_INT offset2
, HOST_WIDE_INT max_size2
,
580 /* If one reference is a component references through pointers try to find a
581 common base and apply offset based disambiguation. This handles
583 struct A { int i; int j; } *q;
584 struct B { struct A a; int k; } *p;
585 disambiguating q->i and p->a.j. */
589 /* Now search for the type1 in the access path of ref2. This
590 would be a common base for doing offset based disambiguation on. */
592 while (handled_component_p (*refp
)
593 && same_type_for_tbaa (TREE_TYPE (*refp
), type1
) == 0)
594 refp
= &TREE_OPERAND (*refp
, 0);
595 same_p
= same_type_for_tbaa (TREE_TYPE (*refp
), type1
);
596 /* If we couldn't compare types we have to bail out. */
599 else if (same_p
== 1)
601 HOST_WIDE_INT offadj
, sztmp
, msztmp
;
602 get_ref_base_and_extent (*refp
, &offadj
, &sztmp
, &msztmp
);
604 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
606 /* If we didn't find a common base, try the other way around. */
608 while (handled_component_p (*refp
)
609 && same_type_for_tbaa (TREE_TYPE (*refp
), type2
) == 0)
610 refp
= &TREE_OPERAND (*refp
, 0);
611 same_p
= same_type_for_tbaa (TREE_TYPE (*refp
), type2
);
612 /* If we couldn't compare types we have to bail out. */
615 else if (same_p
== 1)
617 HOST_WIDE_INT offadj
, sztmp
, msztmp
;
618 get_ref_base_and_extent (*refp
, &offadj
, &sztmp
, &msztmp
);
620 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
623 /* If we have two type access paths B1.path1 and B2.path2 they may
624 only alias if either B1 is in B2.path2 or B2 is in B1.path1.
625 But we can still have a path that goes B1.path1...B2.path2 with
626 a part that we do not see. So we can only disambiguate now
627 if there is no B2 in the tail of path1 and no B1 on the
629 if (base1_alias_set
== ref2_alias_set
630 || alias_set_subset_of (base1_alias_set
, ref2_alias_set
))
632 /* If this is ptr vs. decl then we know there is no ptr ... decl path. */
634 return (base2_alias_set
== ref1_alias_set
635 || alias_set_subset_of (base2_alias_set
, ref1_alias_set
));
639 /* Return true if two memory references based on the variables BASE1
640 and BASE2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
641 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. */
644 decl_refs_may_alias_p (tree base1
,
645 HOST_WIDE_INT offset1
, HOST_WIDE_INT max_size1
,
647 HOST_WIDE_INT offset2
, HOST_WIDE_INT max_size2
)
649 gcc_assert (SSA_VAR_P (base1
) && SSA_VAR_P (base2
));
651 /* If both references are based on different variables, they cannot alias. */
652 if (!operand_equal_p (base1
, base2
, 0))
655 /* If both references are based on the same variable, they cannot alias if
656 the accesses do not overlap. */
657 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
660 /* Return true if an indirect reference based on *PTR1 constrained
661 to [OFFSET1, OFFSET1 + MAX_SIZE1) may alias a variable based on BASE2
662 constrained to [OFFSET2, OFFSET2 + MAX_SIZE2). *PTR1 and BASE2 have
663 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
664 in which case they are computed on-demand. REF1 and REF2
665 if non-NULL are the complete memory reference trees. */
668 indirect_ref_may_alias_decl_p (tree ref1
, tree ptr1
,
669 HOST_WIDE_INT offset1
, HOST_WIDE_INT max_size1
,
670 alias_set_type ref1_alias_set
,
671 alias_set_type base1_alias_set
,
672 tree ref2
, tree base2
,
673 HOST_WIDE_INT offset2
, HOST_WIDE_INT max_size2
,
674 alias_set_type ref2_alias_set
,
675 alias_set_type base2_alias_set
)
677 /* If only one reference is based on a variable, they cannot alias if
678 the pointer access is beyond the extent of the variable access.
679 (the pointer base cannot validly point to an offset less than zero
681 They also cannot alias if the pointer may not point to the decl. */
683 && !ranges_overlap_p (offset1
, max_size1
, 0, offset2
+ max_size2
))
685 if (!ptr_deref_may_alias_decl_p (ptr1
, base2
))
688 /* Disambiguations that rely on strict aliasing rules follow. */
689 if (!flag_strict_aliasing
)
692 /* If the alias set for a pointer access is zero all bets are off. */
693 if (base1_alias_set
== -1)
694 base1_alias_set
= get_deref_alias_set (ptr1
);
695 if (base1_alias_set
== 0)
697 if (base2_alias_set
== -1)
698 base2_alias_set
= get_alias_set (base2
);
700 /* If both references are through the same type, they do not alias
701 if the accesses do not overlap. This does extra disambiguation
702 for mixed/pointer accesses but requires strict aliasing. */
703 if (same_type_for_tbaa (TREE_TYPE (TREE_TYPE (ptr1
)),
704 TREE_TYPE (base2
)) == 1)
705 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
707 /* The only way to access a variable is through a pointer dereference
708 of the same alias set or a subset of it. */
709 if (base1_alias_set
!= base2_alias_set
710 && !alias_set_subset_of (base1_alias_set
, base2_alias_set
))
713 /* Do access-path based disambiguation. */
715 && handled_component_p (ref1
)
716 && handled_component_p (ref2
))
717 return aliasing_component_refs_p (ref1
, TREE_TYPE (TREE_TYPE (ptr1
)),
718 ref1_alias_set
, base1_alias_set
,
720 ref2
, TREE_TYPE (base2
),
721 ref2_alias_set
, base2_alias_set
,
722 offset2
, max_size2
, true);
727 /* Return true if two indirect references based on *PTR1
728 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
729 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have
730 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
731 in which case they are computed on-demand. REF1 and REF2
732 if non-NULL are the complete memory reference trees. */
735 indirect_refs_may_alias_p (tree ref1
, tree ptr1
,
736 HOST_WIDE_INT offset1
, HOST_WIDE_INT max_size1
,
737 alias_set_type ref1_alias_set
,
738 alias_set_type base1_alias_set
,
739 tree ref2
, tree ptr2
,
740 HOST_WIDE_INT offset2
, HOST_WIDE_INT max_size2
,
741 alias_set_type ref2_alias_set
,
742 alias_set_type base2_alias_set
)
744 /* If both bases are based on pointers they cannot alias if they may not
745 point to the same memory object or if they point to the same object
746 and the accesses do not overlap. */
747 if (operand_equal_p (ptr1
, ptr2
, 0))
748 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
749 if (!ptr_derefs_may_alias_p (ptr1
, ptr2
))
752 /* Disambiguations that rely on strict aliasing rules follow. */
753 if (!flag_strict_aliasing
)
756 /* If the alias set for a pointer access is zero all bets are off. */
757 if (base1_alias_set
== -1)
758 base1_alias_set
= get_deref_alias_set (ptr1
);
759 if (base1_alias_set
== 0)
761 if (base2_alias_set
== -1)
762 base2_alias_set
= get_deref_alias_set (ptr2
);
763 if (base2_alias_set
== 0)
766 /* If both references are through the same type, they do not alias
767 if the accesses do not overlap. This does extra disambiguation
768 for mixed/pointer accesses but requires strict aliasing. */
769 if (same_type_for_tbaa (TREE_TYPE (TREE_TYPE (ptr1
)),
770 TREE_TYPE (TREE_TYPE (ptr2
))) == 1)
771 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
773 /* Do type-based disambiguation. */
774 if (base1_alias_set
!= base2_alias_set
775 && !alias_sets_conflict_p (base1_alias_set
, base2_alias_set
))
778 /* Do access-path based disambiguation. */
780 && handled_component_p (ref1
)
781 && handled_component_p (ref2
))
782 return aliasing_component_refs_p (ref1
, TREE_TYPE (TREE_TYPE (ptr1
)),
783 ref1_alias_set
, base1_alias_set
,
785 ref2
, TREE_TYPE (TREE_TYPE (ptr2
)),
786 ref2_alias_set
, base2_alias_set
,
787 offset2
, max_size2
, false);
792 /* Return true, if the two memory references REF1 and REF2 may alias. */
795 refs_may_alias_p_1 (ao_ref
*ref1
, ao_ref
*ref2
, bool tbaa_p
)
798 HOST_WIDE_INT offset1
= 0, offset2
= 0;
799 HOST_WIDE_INT max_size1
= -1, max_size2
= -1;
800 bool var1_p
, var2_p
, ind1_p
, ind2_p
;
803 gcc_assert ((!ref1
->ref
804 || SSA_VAR_P (ref1
->ref
)
805 || handled_component_p (ref1
->ref
)
806 || INDIRECT_REF_P (ref1
->ref
)
807 || TREE_CODE (ref1
->ref
) == TARGET_MEM_REF
808 || TREE_CODE (ref1
->ref
) == CONST_DECL
)
810 || SSA_VAR_P (ref2
->ref
)
811 || handled_component_p (ref2
->ref
)
812 || INDIRECT_REF_P (ref2
->ref
)
813 || TREE_CODE (ref2
->ref
) == TARGET_MEM_REF
814 || TREE_CODE (ref2
->ref
) == CONST_DECL
));
816 /* Decompose the references into their base objects and the access. */
817 base1
= ao_ref_base (ref1
);
818 offset1
= ref1
->offset
;
819 max_size1
= ref1
->max_size
;
820 base2
= ao_ref_base (ref2
);
821 offset2
= ref2
->offset
;
822 max_size2
= ref2
->max_size
;
824 /* We can end up with registers or constants as bases for example from
825 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
826 which is seen as a struct copy. */
827 if (TREE_CODE (base1
) == SSA_NAME
828 || TREE_CODE (base2
) == SSA_NAME
829 || TREE_CODE (base1
) == CONST_DECL
830 || TREE_CODE (base2
) == CONST_DECL
831 || is_gimple_min_invariant (base1
)
832 || is_gimple_min_invariant (base2
))
835 /* We can end up refering to code via function decls. As we likely
836 do not properly track code aliases conservatively bail out. */
837 if (TREE_CODE (base1
) == FUNCTION_DECL
838 || TREE_CODE (base2
) == FUNCTION_DECL
)
841 /* Defer to simple offset based disambiguation if we have
842 references based on two decls. Do this before defering to
843 TBAA to handle must-alias cases in conformance with the
844 GCC extension of allowing type-punning through unions. */
845 var1_p
= SSA_VAR_P (base1
);
846 var2_p
= SSA_VAR_P (base2
);
847 if (var1_p
&& var2_p
)
848 return decl_refs_may_alias_p (base1
, offset1
, max_size1
,
849 base2
, offset2
, max_size2
);
851 ind1_p
= INDIRECT_REF_P (base1
);
852 ind2_p
= INDIRECT_REF_P (base2
);
853 /* Canonicalize the pointer-vs-decl case. */
854 if (ind1_p
&& var2_p
)
859 tmp1
= offset1
; offset1
= offset2
; offset2
= tmp1
;
860 tmp1
= max_size1
; max_size1
= max_size2
; max_size2
= tmp1
;
861 tmp2
= base1
; base1
= base2
; base2
= tmp2
;
862 tmp3
= ref1
; ref1
= ref2
; ref2
= tmp3
;
869 /* If we are about to disambiguate pointer-vs-decl try harder to
870 see must-aliases and give leeway to some invalid cases.
871 This covers a pretty minimal set of cases only and does not
872 when called from the RTL oracle. It handles cases like
877 and also fixes gfortran.dg/lto/pr40725. */
880 && gimple_in_ssa_p (cfun
)
881 && TREE_CODE (TREE_OPERAND (base2
, 0)) == SSA_NAME
)
883 gimple def_stmt
= SSA_NAME_DEF_STMT (TREE_OPERAND (base2
, 0));
884 while (is_gimple_assign (def_stmt
)
885 && (gimple_assign_rhs_code (def_stmt
) == SSA_NAME
886 || CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt
))))
888 tree rhs
= gimple_assign_rhs1 (def_stmt
);
889 HOST_WIDE_INT offset
, size
, max_size
;
891 /* Look through SSA name copies and pointer conversions. */
892 if (TREE_CODE (rhs
) == SSA_NAME
893 && POINTER_TYPE_P (TREE_TYPE (rhs
)))
895 def_stmt
= SSA_NAME_DEF_STMT (rhs
);
898 if (TREE_CODE (rhs
) != ADDR_EXPR
)
901 /* If the pointer is defined as an address based on a decl
902 use plain offset disambiguation and ignore TBAA. */
903 rhs
= TREE_OPERAND (rhs
, 0);
904 rhs
= get_ref_base_and_extent (rhs
, &offset
, &size
, &max_size
);
912 return decl_refs_may_alias_p (base1
, offset1
, max_size1
,
913 base2
, offset2
, max_size2
);
916 /* Do not continue looking through &p->x to limit time
922 /* First defer to TBAA if possible. */
924 && flag_strict_aliasing
925 && !alias_sets_conflict_p (ao_ref_alias_set (ref1
),
926 ao_ref_alias_set (ref2
)))
929 /* If one reference is a TARGET_MEM_REF weird things are allowed. Still
930 TBAA disambiguation based on the access type is possible, so bail
931 out only after that check. */
932 if ((ref1
->ref
&& TREE_CODE (ref1
->ref
) == TARGET_MEM_REF
)
933 || (ref2
->ref
&& TREE_CODE (ref2
->ref
) == TARGET_MEM_REF
))
936 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */
937 set
= tbaa_p
? -1 : 0;
938 if (var1_p
&& ind2_p
)
939 return indirect_ref_may_alias_decl_p (ref2
->ref
, TREE_OPERAND (base2
, 0),
941 ao_ref_alias_set (ref2
), set
,
944 ao_ref_alias_set (ref1
), set
);
945 else if (ind1_p
&& ind2_p
)
946 return indirect_refs_may_alias_p (ref1
->ref
, TREE_OPERAND (base1
, 0),
948 ao_ref_alias_set (ref1
), set
,
949 ref2
->ref
, TREE_OPERAND (base2
, 0),
951 ao_ref_alias_set (ref2
), set
);
957 refs_may_alias_p (tree ref1
, tree ref2
)
961 ao_ref_init (&r1
, ref1
);
962 ao_ref_init (&r2
, ref2
);
963 res
= refs_may_alias_p_1 (&r1
, &r2
, true);
965 ++alias_stats
.refs_may_alias_p_may_alias
;
967 ++alias_stats
.refs_may_alias_p_no_alias
;
971 /* Returns true if there is a anti-dependence for the STORE that
972 executes after the LOAD. */
975 refs_anti_dependent_p (tree load
, tree store
)
978 ao_ref_init (&r1
, load
);
979 ao_ref_init (&r2
, store
);
980 return refs_may_alias_p_1 (&r1
, &r2
, false);
983 /* Returns true if there is a output dependence for the stores
984 STORE1 and STORE2. */
987 refs_output_dependent_p (tree store1
, tree store2
)
990 ao_ref_init (&r1
, store1
);
991 ao_ref_init (&r2
, store2
);
992 return refs_may_alias_p_1 (&r1
, &r2
, false);
995 /* If the call CALL may use the memory reference REF return true,
996 otherwise return false. */
999 ref_maybe_used_by_call_p_1 (gimple call
, ao_ref
*ref
)
1003 int flags
= gimple_call_flags (call
);
1005 /* Const functions without a static chain do not implicitly use memory. */
1006 if (!gimple_call_chain (call
)
1007 && (flags
& (ECF_CONST
|ECF_NOVOPS
)))
1010 base
= ao_ref_base (ref
);
1014 /* If the reference is based on a decl that is not aliased the call
1015 cannot possibly use it. */
1017 && !may_be_aliased (base
)
1018 /* But local statics can be used through recursion. */
1019 && !is_global_var (base
))
1022 callee
= gimple_call_fndecl (call
);
1024 /* Handle those builtin functions explicitly that do not act as
1025 escape points. See tree-ssa-structalias.c:find_func_aliases
1026 for the list of builtins we might need to handle here. */
1027 if (callee
!= NULL_TREE
1028 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
)
1029 switch (DECL_FUNCTION_CODE (callee
))
1031 /* All the following functions clobber memory pointed to by
1032 their first argument. */
1033 case BUILT_IN_STRCPY
:
1034 case BUILT_IN_STRNCPY
:
1035 case BUILT_IN_MEMCPY
:
1036 case BUILT_IN_MEMMOVE
:
1037 case BUILT_IN_MEMPCPY
:
1038 case BUILT_IN_STPCPY
:
1039 case BUILT_IN_STPNCPY
:
1040 case BUILT_IN_STRCAT
:
1041 case BUILT_IN_STRNCAT
:
1044 tree size
= NULL_TREE
;
1045 if (gimple_call_num_args (call
) == 3)
1046 size
= gimple_call_arg (call
, 2);
1047 ao_ref_init_from_ptr_and_size (&dref
,
1048 gimple_call_arg (call
, 1),
1050 return refs_may_alias_p_1 (&dref
, ref
, false);
1052 case BUILT_IN_BCOPY
:
1055 tree size
= gimple_call_arg (call
, 2);
1056 ao_ref_init_from_ptr_and_size (&dref
,
1057 gimple_call_arg (call
, 0),
1059 return refs_may_alias_p_1 (&dref
, ref
, false);
1061 /* The following builtins do not read from memory. */
1063 case BUILT_IN_MALLOC
:
1064 case BUILT_IN_CALLOC
:
1065 case BUILT_IN_MEMSET
:
1066 case BUILT_IN_FREXP
:
1067 case BUILT_IN_FREXPF
:
1068 case BUILT_IN_FREXPL
:
1069 case BUILT_IN_GAMMA_R
:
1070 case BUILT_IN_GAMMAF_R
:
1071 case BUILT_IN_GAMMAL_R
:
1072 case BUILT_IN_LGAMMA_R
:
1073 case BUILT_IN_LGAMMAF_R
:
1074 case BUILT_IN_LGAMMAL_R
:
1076 case BUILT_IN_MODFF
:
1077 case BUILT_IN_MODFL
:
1078 case BUILT_IN_REMQUO
:
1079 case BUILT_IN_REMQUOF
:
1080 case BUILT_IN_REMQUOL
:
1081 case BUILT_IN_SINCOS
:
1082 case BUILT_IN_SINCOSF
:
1083 case BUILT_IN_SINCOSL
:
1087 /* Fallthru to general call handling. */;
1090 /* Check if base is a global static variable that is not read
1092 if (TREE_CODE (base
) == VAR_DECL
1093 && TREE_STATIC (base
)
1094 && !TREE_PUBLIC (base
))
1098 if (callee
!= NULL_TREE
1100 = ipa_reference_get_not_read_global (cgraph_node (callee
)))
1101 && bitmap_bit_p (not_read
, DECL_UID (base
)))
1105 /* If the base variable is call-used or call-clobbered then
1107 if (flags
& (ECF_PURE
|ECF_CONST
|ECF_LOOPING_CONST_OR_PURE
|ECF_NOVOPS
))
1111 if (is_call_used (base
))
1114 else if (INDIRECT_REF_P (base
)
1115 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
1117 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (TREE_OPERAND (base
, 0));
1121 if (pt_solution_includes_global (&pi
->pt
)
1122 || pt_solutions_intersect (&cfun
->gimple_df
->callused
, &pi
->pt
)
1123 || pt_solutions_intersect (&cfun
->gimple_df
->escaped
, &pi
->pt
))
1133 if (is_call_clobbered (base
))
1136 else if (INDIRECT_REF_P (base
)
1137 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
1139 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (TREE_OPERAND (base
, 0));
1143 if (pt_solution_includes_global (&pi
->pt
)
1144 || pt_solutions_intersect (&cfun
->gimple_df
->escaped
, &pi
->pt
))
1151 /* Inspect call arguments for passed-by-value aliases. */
1153 for (i
= 0; i
< gimple_call_num_args (call
); ++i
)
1155 tree op
= gimple_call_arg (call
, i
);
1157 if (TREE_CODE (op
) == WITH_SIZE_EXPR
)
1158 op
= TREE_OPERAND (op
, 0);
1160 if (TREE_CODE (op
) != SSA_NAME
1161 && !is_gimple_min_invariant (op
))
1164 ao_ref_init (&r
, op
);
1165 if (refs_may_alias_p_1 (&r
, ref
, true))
1174 ref_maybe_used_by_call_p (gimple call
, tree ref
)
1178 ao_ref_init (&r
, ref
);
1179 res
= ref_maybe_used_by_call_p_1 (call
, &r
);
1181 ++alias_stats
.ref_maybe_used_by_call_p_may_alias
;
1183 ++alias_stats
.ref_maybe_used_by_call_p_no_alias
;
1188 /* If the statement STMT may use the memory reference REF return
1189 true, otherwise return false. */
1192 ref_maybe_used_by_stmt_p (gimple stmt
, tree ref
)
1194 if (is_gimple_assign (stmt
))
1198 /* All memory assign statements are single. */
1199 if (!gimple_assign_single_p (stmt
))
1202 rhs
= gimple_assign_rhs1 (stmt
);
1203 if (is_gimple_reg (rhs
)
1204 || is_gimple_min_invariant (rhs
)
1205 || gimple_assign_rhs_code (stmt
) == CONSTRUCTOR
)
1208 return refs_may_alias_p (rhs
, ref
);
1210 else if (is_gimple_call (stmt
))
1211 return ref_maybe_used_by_call_p (stmt
, ref
);
1216 /* If the call in statement CALL may clobber the memory reference REF
1217 return true, otherwise return false. */
1220 call_may_clobber_ref_p_1 (gimple call
, ao_ref
*ref
)
1225 /* If the call is pure or const it cannot clobber anything. */
1226 if (gimple_call_flags (call
)
1227 & (ECF_PURE
|ECF_CONST
|ECF_LOOPING_CONST_OR_PURE
|ECF_NOVOPS
))
1230 base
= ao_ref_base (ref
);
1234 if (TREE_CODE (base
) == SSA_NAME
1235 || CONSTANT_CLASS_P (base
))
1238 /* If the reference is based on a decl that is not aliased the call
1239 cannot possibly clobber it. */
1241 && !may_be_aliased (base
)
1242 /* But local non-readonly statics can be modified through recursion
1243 or the call may implement a threading barrier which we must
1244 treat as may-def. */
1245 && (TREE_READONLY (base
)
1246 || !is_global_var (base
)))
1249 callee
= gimple_call_fndecl (call
);
1251 /* Handle those builtin functions explicitly that do not act as
1252 escape points. See tree-ssa-structalias.c:find_func_aliases
1253 for the list of builtins we might need to handle here. */
1254 if (callee
!= NULL_TREE
1255 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
)
1256 switch (DECL_FUNCTION_CODE (callee
))
1258 /* All the following functions clobber memory pointed to by
1259 their first argument. */
1260 case BUILT_IN_STRCPY
:
1261 case BUILT_IN_STRNCPY
:
1262 case BUILT_IN_MEMCPY
:
1263 case BUILT_IN_MEMMOVE
:
1264 case BUILT_IN_MEMPCPY
:
1265 case BUILT_IN_STPCPY
:
1266 case BUILT_IN_STPNCPY
:
1267 case BUILT_IN_STRCAT
:
1268 case BUILT_IN_STRNCAT
:
1269 case BUILT_IN_MEMSET
:
1272 tree size
= NULL_TREE
;
1273 if (gimple_call_num_args (call
) == 3)
1274 size
= gimple_call_arg (call
, 2);
1275 ao_ref_init_from_ptr_and_size (&dref
,
1276 gimple_call_arg (call
, 0),
1278 return refs_may_alias_p_1 (&dref
, ref
, false);
1280 case BUILT_IN_BCOPY
:
1283 tree size
= gimple_call_arg (call
, 2);
1284 ao_ref_init_from_ptr_and_size (&dref
,
1285 gimple_call_arg (call
, 1),
1287 return refs_may_alias_p_1 (&dref
, ref
, false);
1289 /* Allocating memory does not have any side-effects apart from
1290 being the definition point for the pointer. */
1291 case BUILT_IN_MALLOC
:
1292 case BUILT_IN_CALLOC
:
1293 /* Unix98 specifies that errno is set on allocation failure.
1294 Until we properly can track the errno location assume it
1295 is not a local decl but external or anonymous storage in
1296 a different translation unit. Also assume it is of
1297 type int as required by the standard. */
1299 && TREE_TYPE (base
) == integer_type_node
)
1301 struct ptr_info_def
*pi
;
1303 && !TREE_STATIC (base
))
1305 else if (INDIRECT_REF_P (base
)
1306 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
1307 && (pi
= SSA_NAME_PTR_INFO (TREE_OPERAND (base
, 0))))
1308 return pi
->pt
.anything
|| pi
->pt
.nonlocal
;
1311 /* Freeing memory kills the pointed-to memory. More importantly
1312 the call has to serve as a barrier for moving loads and stores
1316 tree ptr
= gimple_call_arg (call
, 0);
1317 return ptr_deref_may_alias_ref_p_1 (ptr
, ref
);
1319 case BUILT_IN_GAMMA_R
:
1320 case BUILT_IN_GAMMAF_R
:
1321 case BUILT_IN_GAMMAL_R
:
1322 case BUILT_IN_LGAMMA_R
:
1323 case BUILT_IN_LGAMMAF_R
:
1324 case BUILT_IN_LGAMMAL_R
:
1326 tree out
= gimple_call_arg (call
, 1);
1327 if (ptr_deref_may_alias_ref_p_1 (out
, ref
))
1329 if (flag_errno_math
)
1333 case BUILT_IN_FREXP
:
1334 case BUILT_IN_FREXPF
:
1335 case BUILT_IN_FREXPL
:
1337 case BUILT_IN_MODFF
:
1338 case BUILT_IN_MODFL
:
1340 tree out
= gimple_call_arg (call
, 1);
1341 return ptr_deref_may_alias_ref_p_1 (out
, ref
);
1343 case BUILT_IN_REMQUO
:
1344 case BUILT_IN_REMQUOF
:
1345 case BUILT_IN_REMQUOL
:
1347 tree out
= gimple_call_arg (call
, 2);
1348 if (ptr_deref_may_alias_ref_p_1 (out
, ref
))
1350 if (flag_errno_math
)
1354 case BUILT_IN_SINCOS
:
1355 case BUILT_IN_SINCOSF
:
1356 case BUILT_IN_SINCOSL
:
1358 tree sin
= gimple_call_arg (call
, 1);
1359 tree cos
= gimple_call_arg (call
, 2);
1360 return (ptr_deref_may_alias_ref_p_1 (sin
, ref
)
1361 || ptr_deref_may_alias_ref_p_1 (cos
, ref
));
1364 /* Fallthru to general call handling. */;
1367 /* Check if base is a global static variable that is not written
1369 if (callee
!= NULL_TREE
1370 && TREE_CODE (base
) == VAR_DECL
1371 && TREE_STATIC (base
)
1372 && !TREE_PUBLIC (base
))
1377 = ipa_reference_get_not_written_global (cgraph_node (callee
)))
1378 && bitmap_bit_p (not_written
, DECL_UID (base
)))
1383 return is_call_clobbered (base
);
1384 else if (INDIRECT_REF_P (base
)
1385 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
1387 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (TREE_OPERAND (base
, 0));
1391 return (pt_solution_includes_global (&pi
->pt
)
1392 || pt_solutions_intersect (&cfun
->gimple_df
->escaped
, &pi
->pt
));
1398 static bool ATTRIBUTE_UNUSED
1399 call_may_clobber_ref_p (gimple call
, tree ref
)
1403 ao_ref_init (&r
, ref
);
1404 res
= call_may_clobber_ref_p_1 (call
, &r
);
1406 ++alias_stats
.call_may_clobber_ref_p_may_alias
;
1408 ++alias_stats
.call_may_clobber_ref_p_no_alias
;
1413 /* If the statement STMT may clobber the memory reference REF return true,
1414 otherwise return false. */
1417 stmt_may_clobber_ref_p_1 (gimple stmt
, ao_ref
*ref
)
1419 if (is_gimple_call (stmt
))
1421 tree lhs
= gimple_call_lhs (stmt
);
1423 && !is_gimple_reg (lhs
))
1426 ao_ref_init (&r
, lhs
);
1427 if (refs_may_alias_p_1 (ref
, &r
, true))
1431 return call_may_clobber_ref_p_1 (stmt
, ref
);
1433 else if (is_gimple_assign (stmt
))
1436 ao_ref_init (&r
, gimple_assign_lhs (stmt
));
1437 return refs_may_alias_p_1 (ref
, &r
, true);
1439 else if (gimple_code (stmt
) == GIMPLE_ASM
)
1446 stmt_may_clobber_ref_p (gimple stmt
, tree ref
)
1449 ao_ref_init (&r
, ref
);
1450 return stmt_may_clobber_ref_p_1 (stmt
, &r
);
1454 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand
1455 TARGET or a statement clobbering the memory reference REF in which
1456 case false is returned. The walk starts with VUSE, one argument of PHI. */
1459 maybe_skip_until (gimple phi
, tree target
, ao_ref
*ref
,
1460 tree vuse
, bitmap
*visited
)
1463 *visited
= BITMAP_ALLOC (NULL
);
1465 bitmap_set_bit (*visited
, SSA_NAME_VERSION (PHI_RESULT (phi
)));
1467 /* Walk until we hit the target. */
1468 while (vuse
!= target
)
1470 gimple def_stmt
= SSA_NAME_DEF_STMT (vuse
);
1471 /* Recurse for PHI nodes. */
1472 if (gimple_code (def_stmt
) == GIMPLE_PHI
)
1474 /* An already visited PHI node ends the walk successfully. */
1475 if (bitmap_bit_p (*visited
, SSA_NAME_VERSION (PHI_RESULT (def_stmt
))))
1477 vuse
= get_continuation_for_phi (def_stmt
, ref
, visited
);
1482 /* A clobbering statement or the end of the IL ends it failing. */
1483 else if (gimple_nop_p (def_stmt
)
1484 || stmt_may_clobber_ref_p_1 (def_stmt
, ref
))
1486 vuse
= gimple_vuse (def_stmt
);
1491 /* Starting from a PHI node for the virtual operand of the memory reference
1492 REF find a continuation virtual operand that allows to continue walking
1493 statements dominating PHI skipping only statements that cannot possibly
1494 clobber REF. Returns NULL_TREE if no suitable virtual operand can
1498 get_continuation_for_phi (gimple phi
, ao_ref
*ref
, bitmap
*visited
)
1500 unsigned nargs
= gimple_phi_num_args (phi
);
1502 /* Through a single-argument PHI we can simply look through. */
1504 return PHI_ARG_DEF (phi
, 0);
1506 /* For two arguments try to skip non-aliasing code until we hit
1507 the phi argument definition that dominates the other one. */
1510 tree arg0
= PHI_ARG_DEF (phi
, 0);
1511 tree arg1
= PHI_ARG_DEF (phi
, 1);
1512 gimple def0
= SSA_NAME_DEF_STMT (arg0
);
1513 gimple def1
= SSA_NAME_DEF_STMT (arg1
);
1518 else if (gimple_nop_p (def0
)
1519 || (!gimple_nop_p (def1
)
1520 && dominated_by_p (CDI_DOMINATORS
,
1521 gimple_bb (def1
), gimple_bb (def0
))))
1523 if (maybe_skip_until (phi
, arg0
, ref
, arg1
, visited
))
1526 else if (gimple_nop_p (def1
)
1527 || dominated_by_p (CDI_DOMINATORS
,
1528 gimple_bb (def0
), gimple_bb (def1
)))
1530 if (maybe_skip_until (phi
, arg1
, ref
, arg0
, visited
))
1533 /* Special case of a diamond:
1535 goto (cond) ? L1 : L2
1536 L1: store1 = ... #MEM_2 = vuse(MEM_1)
1538 L2: store2 = ... #MEM_3 = vuse(MEM_1)
1539 L3: MEM_4 = PHI<MEM_2, MEM_3>
1540 We were called with the PHI at L3, MEM_2 and MEM_3 don't
1541 dominate each other, but still we can easily skip this PHI node
1542 if we recognize that the vuse MEM operand is the same for both,
1543 and that we can skip both statements (they don't clobber us).
1544 This is still linear. Don't use maybe_skip_until, that might
1545 potentially be slow. */
1546 else if ((common_vuse
= gimple_vuse (def0
))
1547 && common_vuse
== gimple_vuse (def1
))
1549 if (!stmt_may_clobber_ref_p_1 (def0
, ref
)
1550 && !stmt_may_clobber_ref_p_1 (def1
, ref
))
1558 /* Based on the memory reference REF and its virtual use VUSE call
1559 WALKER for each virtual use that is equivalent to VUSE, including VUSE
1560 itself. That is, for each virtual use for which its defining statement
1561 does not clobber REF.
1563 WALKER is called with REF, the current virtual use and DATA. If
1564 WALKER returns non-NULL the walk stops and its result is returned.
1565 At the end of a non-successful walk NULL is returned.
1567 TRANSLATE if non-NULL is called with a pointer to REF, the virtual
1568 use which definition is a statement that may clobber REF and DATA.
1569 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
1570 If TRANSLATE returns non-NULL the walk stops and its result is returned.
1571 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
1572 to adjust REF and *DATA to make that valid.
1574 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
1577 walk_non_aliased_vuses (ao_ref
*ref
, tree vuse
,
1578 void *(*walker
)(ao_ref
*, tree
, void *),
1579 void *(*translate
)(ao_ref
*, tree
, void *), void *data
)
1581 bitmap visited
= NULL
;
1584 timevar_push (TV_ALIAS_STMT_WALK
);
1590 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1591 res
= (*walker
) (ref
, vuse
, data
);
1595 def_stmt
= SSA_NAME_DEF_STMT (vuse
);
1596 if (gimple_nop_p (def_stmt
))
1598 else if (gimple_code (def_stmt
) == GIMPLE_PHI
)
1599 vuse
= get_continuation_for_phi (def_stmt
, ref
, &visited
);
1602 if (stmt_may_clobber_ref_p_1 (def_stmt
, ref
))
1606 res
= (*translate
) (ref
, vuse
, data
);
1607 /* Failed lookup and translation. */
1608 if (res
== (void *)-1)
1613 /* Lookup succeeded. */
1614 else if (res
!= NULL
)
1616 /* Translation succeeded, continue walking. */
1618 vuse
= gimple_vuse (def_stmt
);
1624 BITMAP_FREE (visited
);
1626 timevar_pop (TV_ALIAS_STMT_WALK
);
1632 /* Based on the memory reference REF call WALKER for each vdef which
1633 defining statement may clobber REF, starting with VDEF. If REF
1634 is NULL_TREE, each defining statement is visited.
1636 WALKER is called with REF, the current vdef and DATA. If WALKER
1637 returns true the walk is stopped, otherwise it continues.
1639 At PHI nodes walk_aliased_vdefs forks into one walk for reach
1640 PHI argument (but only one walk continues on merge points), the
1641 return value is true if any of the walks was successful.
1643 The function returns the number of statements walked. */
1646 walk_aliased_vdefs_1 (ao_ref
*ref
, tree vdef
,
1647 bool (*walker
)(ao_ref
*, tree
, void *), void *data
,
1648 bitmap
*visited
, unsigned int cnt
)
1652 gimple def_stmt
= SSA_NAME_DEF_STMT (vdef
);
1655 && !bitmap_set_bit (*visited
, SSA_NAME_VERSION (vdef
)))
1658 if (gimple_nop_p (def_stmt
))
1660 else if (gimple_code (def_stmt
) == GIMPLE_PHI
)
1664 *visited
= BITMAP_ALLOC (NULL
);
1665 for (i
= 0; i
< gimple_phi_num_args (def_stmt
); ++i
)
1666 cnt
+= walk_aliased_vdefs_1 (ref
, gimple_phi_arg_def (def_stmt
, i
),
1667 walker
, data
, visited
, 0);
1671 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1674 || stmt_may_clobber_ref_p_1 (def_stmt
, ref
))
1675 && (*walker
) (ref
, vdef
, data
))
1678 vdef
= gimple_vuse (def_stmt
);
1684 walk_aliased_vdefs (ao_ref
*ref
, tree vdef
,
1685 bool (*walker
)(ao_ref
*, tree
, void *), void *data
,
1688 bitmap local_visited
= NULL
;
1691 timevar_push (TV_ALIAS_STMT_WALK
);
1693 ret
= walk_aliased_vdefs_1 (ref
, vdef
, walker
, data
,
1694 visited
? visited
: &local_visited
, 0);
1696 BITMAP_FREE (local_visited
);
1698 timevar_pop (TV_ALIAS_STMT_WALK
);