1 /* Alias analysis for trees.
2 Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009
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 return pt_solution_includes (&pi
->pt
, decl
);
214 /* Return true if dereferenced PTR1 and PTR2 may alias.
215 The caller is responsible for applying TBAA to see if accesses
216 through PTR1 and PTR2 may conflict at all. */
219 ptr_derefs_may_alias_p (tree ptr1
, tree ptr2
)
221 struct ptr_info_def
*pi1
, *pi2
;
223 gcc_assert ((TREE_CODE (ptr1
) == SSA_NAME
224 || TREE_CODE (ptr1
) == ADDR_EXPR
225 || TREE_CODE (ptr1
) == INTEGER_CST
)
226 && (TREE_CODE (ptr2
) == SSA_NAME
227 || TREE_CODE (ptr2
) == ADDR_EXPR
228 || TREE_CODE (ptr2
) == INTEGER_CST
));
230 /* ADDR_EXPR pointers either just offset another pointer or directly
231 specify the pointed-to set. */
232 if (TREE_CODE (ptr1
) == ADDR_EXPR
)
234 tree base
= get_base_address (TREE_OPERAND (ptr1
, 0));
236 && INDIRECT_REF_P (base
))
237 ptr1
= TREE_OPERAND (base
, 0);
240 return ptr_deref_may_alias_decl_p (ptr2
, base
);
244 if (TREE_CODE (ptr2
) == ADDR_EXPR
)
246 tree base
= get_base_address (TREE_OPERAND (ptr2
, 0));
248 && INDIRECT_REF_P (base
))
249 ptr2
= TREE_OPERAND (base
, 0);
252 return ptr_deref_may_alias_decl_p (ptr1
, base
);
257 /* We can end up with dereferencing constant pointers.
258 Just bail out in this case. */
259 if (TREE_CODE (ptr1
) == INTEGER_CST
260 || TREE_CODE (ptr2
) == INTEGER_CST
)
263 /* We may end up with two empty points-to solutions for two same pointers.
264 In this case we still want to say both pointers alias, so shortcut
269 /* If we do not have useful points-to information for either pointer
270 we cannot disambiguate anything else. */
271 pi1
= SSA_NAME_PTR_INFO (ptr1
);
272 pi2
= SSA_NAME_PTR_INFO (ptr2
);
276 /* ??? This does not use TBAA to prune decls from the intersection
277 that not both pointers may access. */
278 return pt_solutions_intersect (&pi1
->pt
, &pi2
->pt
);
281 /* Return true if dereferencing PTR may alias *REF.
282 The caller is responsible for applying TBAA to see if PTR
283 may access *REF at all. */
286 ptr_deref_may_alias_ref_p_1 (tree ptr
, ao_ref
*ref
)
288 tree base
= ao_ref_base (ref
);
290 if (INDIRECT_REF_P (base
))
291 return ptr_derefs_may_alias_p (ptr
, TREE_OPERAND (base
, 0));
292 else if (SSA_VAR_P (base
))
293 return ptr_deref_may_alias_decl_p (ptr
, base
);
299 ptr_deref_may_alias_ref_p (tree ptr
, tree ref
)
302 ao_ref_init (&r
, ref
);
303 return ptr_deref_may_alias_ref_p_1 (ptr
, &r
);
307 /* Dump alias information on FILE. */
310 dump_alias_info (FILE *file
)
314 = lang_hooks
.decl_printable_name (current_function_decl
, 2);
315 referenced_var_iterator rvi
;
318 fprintf (file
, "\n\nAlias information for %s\n\n", funcname
);
320 fprintf (file
, "Aliased symbols\n\n");
322 FOR_EACH_REFERENCED_VAR (var
, rvi
)
324 if (may_be_aliased (var
))
325 dump_variable (file
, var
);
328 fprintf (file
, "\nCall clobber information\n");
330 fprintf (file
, "\nESCAPED");
331 dump_points_to_solution (file
, &cfun
->gimple_df
->escaped
);
332 fprintf (file
, "\nCALLUSED");
333 dump_points_to_solution (file
, &cfun
->gimple_df
->callused
);
335 fprintf (file
, "\n\nFlow-insensitive points-to information\n\n");
337 for (i
= 1; i
< num_ssa_names
; i
++)
339 tree ptr
= ssa_name (i
);
340 struct ptr_info_def
*pi
;
343 || SSA_NAME_IN_FREE_LIST (ptr
))
346 pi
= SSA_NAME_PTR_INFO (ptr
);
348 dump_points_to_info_for (file
, ptr
);
351 fprintf (file
, "\n");
355 /* Dump alias information on stderr. */
358 debug_alias_info (void)
360 dump_alias_info (stderr
);
364 /* Return the alias information associated with pointer T. It creates a
365 new instance if none existed. */
367 struct ptr_info_def
*
368 get_ptr_info (tree t
)
370 struct ptr_info_def
*pi
;
372 gcc_assert (POINTER_TYPE_P (TREE_TYPE (t
)));
374 pi
= SSA_NAME_PTR_INFO (t
);
377 pi
= GGC_CNEW (struct ptr_info_def
);
378 pt_solution_reset (&pi
->pt
);
379 SSA_NAME_PTR_INFO (t
) = pi
;
385 /* Dump the points-to set *PT into FILE. */
388 dump_points_to_solution (FILE *file
, struct pt_solution
*pt
)
391 fprintf (file
, ", points-to anything");
394 fprintf (file
, ", points-to non-local");
397 fprintf (file
, ", points-to escaped");
400 fprintf (file
, ", points-to NULL");
404 fprintf (file
, ", points-to vars: ");
405 dump_decl_set (file
, pt
->vars
);
406 if (pt
->vars_contains_global
)
407 fprintf (file
, " (includes global vars)");
411 /* Dump points-to information for SSA_NAME PTR into FILE. */
414 dump_points_to_info_for (FILE *file
, tree ptr
)
416 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (ptr
);
418 print_generic_expr (file
, ptr
, dump_flags
);
421 dump_points_to_solution (file
, &pi
->pt
);
423 fprintf (file
, ", points-to anything");
425 fprintf (file
, "\n");
429 /* Dump points-to information for VAR into stderr. */
432 debug_points_to_info_for (tree var
)
434 dump_points_to_info_for (stderr
, var
);
438 /* Initializes the alias-oracle reference representation *R from REF. */
441 ao_ref_init (ao_ref
*r
, tree ref
)
448 r
->ref_alias_set
= -1;
449 r
->base_alias_set
= -1;
452 /* Returns the base object of the memory reference *REF. */
455 ao_ref_base (ao_ref
*ref
)
459 ref
->base
= get_ref_base_and_extent (ref
->ref
, &ref
->offset
, &ref
->size
,
464 /* Returns the base object alias set of the memory reference *REF. */
466 static alias_set_type ATTRIBUTE_UNUSED
467 ao_ref_base_alias_set (ao_ref
*ref
)
469 if (ref
->base_alias_set
!= -1)
470 return ref
->base_alias_set
;
471 ref
->base_alias_set
= get_alias_set (ao_ref_base (ref
));
472 return ref
->base_alias_set
;
475 /* Returns the reference alias set of the memory reference *REF. */
478 ao_ref_alias_set (ao_ref
*ref
)
480 if (ref
->ref_alias_set
!= -1)
481 return ref
->ref_alias_set
;
482 ref
->ref_alias_set
= get_alias_set (ref
->ref
);
483 return ref
->ref_alias_set
;
486 /* Return 1 if TYPE1 and TYPE2 are to be considered equivalent for the
487 purpose of TBAA. Return 0 if they are distinct and -1 if we cannot
491 same_type_for_tbaa (tree type1
, tree type2
)
493 type1
= TYPE_MAIN_VARIANT (type1
);
494 type2
= TYPE_MAIN_VARIANT (type2
);
496 /* If we would have to do structural comparison bail out. */
497 if (TYPE_STRUCTURAL_EQUALITY_P (type1
)
498 || TYPE_STRUCTURAL_EQUALITY_P (type2
))
501 /* Compare the canonical types. */
502 if (TYPE_CANONICAL (type1
) == TYPE_CANONICAL (type2
))
505 /* ??? Array types are not properly unified in all cases as we have
506 spurious changes in the index types for example. Removing this
507 causes all sorts of problems with the Fortran frontend. */
508 if (TREE_CODE (type1
) == ARRAY_TYPE
509 && TREE_CODE (type2
) == ARRAY_TYPE
)
512 /* The types are known to be not equal. */
516 /* Determine if the two component references REF1 and REF2 which are
517 based on access types TYPE1 and TYPE2 and of which at least one is based
518 on an indirect reference may alias. */
521 nonaliasing_component_refs_p (tree ref1
, tree type1
,
522 HOST_WIDE_INT offset1
, HOST_WIDE_INT max_size1
,
523 tree ref2
, tree type2
,
524 HOST_WIDE_INT offset2
, HOST_WIDE_INT max_size2
)
526 /* If one reference is a component references through pointers try to find a
527 common base and apply offset based disambiguation. This handles
529 struct A { int i; int j; } *q;
530 struct B { struct A a; int k; } *p;
531 disambiguating q->i and p->a.j. */
535 /* Now search for the type1 in the access path of ref2. This
536 would be a common base for doing offset based disambiguation on. */
538 while (handled_component_p (*refp
)
539 && same_type_for_tbaa (TREE_TYPE (*refp
), type1
) == 0)
540 refp
= &TREE_OPERAND (*refp
, 0);
541 same_p
= same_type_for_tbaa (TREE_TYPE (*refp
), type1
);
542 /* If we couldn't compare types we have to bail out. */
545 else if (same_p
== 1)
547 HOST_WIDE_INT offadj
, sztmp
, msztmp
;
548 get_ref_base_and_extent (*refp
, &offadj
, &sztmp
, &msztmp
);
550 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
552 /* If we didn't find a common base, try the other way around. */
554 while (handled_component_p (*refp
)
555 && same_type_for_tbaa (TREE_TYPE (*refp
), type2
) == 0)
556 refp
= &TREE_OPERAND (*refp
, 0);
557 same_p
= same_type_for_tbaa (TREE_TYPE (*refp
), type2
);
558 /* If we couldn't compare types we have to bail out. */
561 else if (same_p
== 1)
563 HOST_WIDE_INT offadj
, sztmp
, msztmp
;
564 get_ref_base_and_extent (*refp
, &offadj
, &sztmp
, &msztmp
);
566 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
568 /* If we have two type access paths B1.path1 and B2.path2 they may
569 only alias if either B1 is in B2.path2 or B2 is in B1.path1. */
573 /* Return true if two memory references based on the variables BASE1
574 and BASE2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1[ and
575 [OFFSET2, OFFSET2 + MAX_SIZE2[ may alias. */
578 decl_refs_may_alias_p (tree base1
,
579 HOST_WIDE_INT offset1
, HOST_WIDE_INT max_size1
,
581 HOST_WIDE_INT offset2
, HOST_WIDE_INT max_size2
)
583 gcc_assert (SSA_VAR_P (base1
) && SSA_VAR_P (base2
));
585 /* If both references are based on different variables, they cannot alias. */
586 if (!operand_equal_p (base1
, base2
, 0))
589 /* If both references are based on the same variable, they cannot alias if
590 the accesses do not overlap. */
591 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
594 /* Return true if an indirect reference based on *PTR1 constrained
595 to [OFFSET1, OFFSET1 + MAX_SIZE1[ may alias a variable based on BASE2
596 constrained to [OFFSET2, OFFSET2 + MAX_SIZE2[. *PTR1 and BASE2 have
597 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
598 in which case they are computed on-demand. REF1 and REF2
599 if non-NULL are the complete memory reference trees. */
602 indirect_ref_may_alias_decl_p (tree ref1
, tree ptr1
,
603 HOST_WIDE_INT offset1
, HOST_WIDE_INT max_size1
,
604 alias_set_type base1_alias_set
,
605 tree ref2
, tree base2
,
606 HOST_WIDE_INT offset2
, HOST_WIDE_INT max_size2
,
607 alias_set_type base2_alias_set
)
609 /* If only one reference is based on a variable, they cannot alias if
610 the pointer access is beyond the extent of the variable access.
611 (the pointer base cannot validly point to an offset less than zero
613 They also cannot alias if the pointer may not point to the decl. */
615 && !ranges_overlap_p (offset1
, max_size1
, 0, offset2
+ max_size2
))
617 if (!ptr_deref_may_alias_decl_p (ptr1
, base2
))
620 /* Disambiguations that rely on strict aliasing rules follow. */
621 if (!flag_strict_aliasing
)
624 /* If the alias set for a pointer access is zero all bets are off. */
625 if (base1_alias_set
== -1)
626 base1_alias_set
= get_deref_alias_set (ptr1
);
627 if (base1_alias_set
== 0)
629 if (base2_alias_set
== -1)
630 base2_alias_set
= get_alias_set (base2
);
632 /* If both references are through the same type, they do not alias
633 if the accesses do not overlap. This does extra disambiguation
634 for mixed/pointer accesses but requires strict aliasing. */
635 if (same_type_for_tbaa (TREE_TYPE (TREE_TYPE (ptr1
)),
636 TREE_TYPE (base2
)) == 1)
637 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
639 /* The only way to access a variable is through a pointer dereference
640 of the same alias set or a subset of it. */
641 if (base1_alias_set
!= base2_alias_set
642 && !alias_set_subset_of (base1_alias_set
, base2_alias_set
))
645 /* Do access-path based disambiguation. */
647 && handled_component_p (ref1
)
648 && handled_component_p (ref2
))
649 return nonaliasing_component_refs_p (ref1
, TREE_TYPE (TREE_TYPE (ptr1
)),
651 ref2
, TREE_TYPE (base2
),
657 /* Return true if two indirect references based on *PTR1
658 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1[ and
659 [OFFSET2, OFFSET2 + MAX_SIZE2[ may alias. *PTR1 and *PTR2 have
660 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
661 in which case they are computed on-demand. REF1 and REF2
662 if non-NULL are the complete memory reference trees. */
665 indirect_refs_may_alias_p (tree ref1
, tree ptr1
,
666 HOST_WIDE_INT offset1
, HOST_WIDE_INT max_size1
,
667 alias_set_type base1_alias_set
,
668 tree ref2
, tree ptr2
,
669 HOST_WIDE_INT offset2
, HOST_WIDE_INT max_size2
,
670 alias_set_type base2_alias_set
)
672 /* If both bases are based on pointers they cannot alias if they may not
673 point to the same memory object or if they point to the same object
674 and the accesses do not overlap. */
675 if (operand_equal_p (ptr1
, ptr2
, 0))
676 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
677 if (!ptr_derefs_may_alias_p (ptr1
, ptr2
))
680 /* Disambiguations that rely on strict aliasing rules follow. */
681 if (!flag_strict_aliasing
)
684 /* If the alias set for a pointer access is zero all bets are off. */
685 if (base1_alias_set
== -1)
686 base1_alias_set
= get_deref_alias_set (ptr1
);
687 if (base1_alias_set
== 0)
689 if (base2_alias_set
== -1)
690 base2_alias_set
= get_deref_alias_set (ptr2
);
691 if (base2_alias_set
== 0)
694 /* If both references are through the same type, they do not alias
695 if the accesses do not overlap. This does extra disambiguation
696 for mixed/pointer accesses but requires strict aliasing. */
697 if (same_type_for_tbaa (TREE_TYPE (TREE_TYPE (ptr1
)),
698 TREE_TYPE (TREE_TYPE (ptr2
))) == 1)
699 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
701 /* Do type-based disambiguation. */
702 if (base1_alias_set
!= base2_alias_set
703 && !alias_sets_conflict_p (base1_alias_set
, base2_alias_set
))
706 /* Do access-path based disambiguation. */
708 && handled_component_p (ref1
)
709 && handled_component_p (ref2
))
710 return nonaliasing_component_refs_p (ref1
, TREE_TYPE (TREE_TYPE (ptr1
)),
712 ref2
, TREE_TYPE (TREE_TYPE (ptr2
)),
718 /* Return true, if the two memory references REF1 and REF2 may alias. */
721 refs_may_alias_p_1 (ao_ref
*ref1
, ao_ref
*ref2
, bool tbaa_p
)
724 HOST_WIDE_INT offset1
= 0, offset2
= 0;
725 HOST_WIDE_INT size1
= -1, size2
= -1;
726 HOST_WIDE_INT max_size1
= -1, max_size2
= -1;
727 bool var1_p
, var2_p
, ind1_p
, ind2_p
;
730 gcc_assert ((!ref1
->ref
731 || SSA_VAR_P (ref1
->ref
)
732 || handled_component_p (ref1
->ref
)
733 || INDIRECT_REF_P (ref1
->ref
)
734 || TREE_CODE (ref1
->ref
) == TARGET_MEM_REF
)
736 || SSA_VAR_P (ref2
->ref
)
737 || handled_component_p (ref2
->ref
)
738 || INDIRECT_REF_P (ref2
->ref
)
739 || TREE_CODE (ref2
->ref
) == TARGET_MEM_REF
));
741 /* Decompose the references into their base objects and the access. */
742 base1
= ao_ref_base (ref1
);
743 offset1
= ref1
->offset
;
745 max_size1
= ref1
->max_size
;
746 base2
= ao_ref_base (ref2
);
747 offset2
= ref2
->offset
;
749 max_size2
= ref2
->max_size
;
751 /* We can end up with registers or constants as bases for example from
752 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
753 which is seen as a struct copy. */
754 if (TREE_CODE (base1
) == SSA_NAME
755 || TREE_CODE (base2
) == SSA_NAME
756 || is_gimple_min_invariant (base1
)
757 || is_gimple_min_invariant (base2
))
760 /* Defer to simple offset based disambiguation if we have
761 references based on two decls. Do this before defering to
762 TBAA to handle must-alias cases in conformance with the
763 GCC extension of allowing type-punning through unions. */
764 var1_p
= SSA_VAR_P (base1
);
765 var2_p
= SSA_VAR_P (base2
);
766 if (var1_p
&& var2_p
)
767 return decl_refs_may_alias_p (base1
, offset1
, max_size1
,
768 base2
, offset2
, max_size2
);
770 /* First defer to TBAA if possible. */
772 && flag_strict_aliasing
773 && !alias_sets_conflict_p (ao_ref_alias_set (ref1
),
774 ao_ref_alias_set (ref2
)))
777 /* If one reference is a TARGET_MEM_REF weird things are allowed. Still
778 TBAA disambiguation based on the access type is possible, so bail
779 out only after that check. */
780 if ((ref1
->ref
&& TREE_CODE (ref1
->ref
) == TARGET_MEM_REF
)
781 || (ref2
->ref
&& TREE_CODE (ref2
->ref
) == TARGET_MEM_REF
))
784 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */
785 ind1_p
= INDIRECT_REF_P (base1
);
786 ind2_p
= INDIRECT_REF_P (base2
);
787 set
= tbaa_p
? -1 : 0;
788 if (var1_p
&& ind2_p
)
789 return indirect_ref_may_alias_decl_p (ref2
->ref
, TREE_OPERAND (base2
, 0),
790 offset2
, max_size2
, set
,
792 offset1
, max_size1
, set
);
793 else if (ind1_p
&& var2_p
)
794 return indirect_ref_may_alias_decl_p (ref1
->ref
, TREE_OPERAND (base1
, 0),
795 offset1
, max_size1
, set
,
797 offset2
, max_size2
, set
);
798 else if (ind1_p
&& ind2_p
)
799 return indirect_refs_may_alias_p (ref1
->ref
, TREE_OPERAND (base1
, 0),
800 offset1
, max_size1
, set
,
801 ref2
->ref
, TREE_OPERAND (base2
, 0),
802 offset2
, max_size2
, set
);
808 refs_may_alias_p (tree ref1
, tree ref2
)
812 ao_ref_init (&r1
, ref1
);
813 ao_ref_init (&r2
, ref2
);
814 res
= refs_may_alias_p_1 (&r1
, &r2
, true);
816 ++alias_stats
.refs_may_alias_p_may_alias
;
818 ++alias_stats
.refs_may_alias_p_no_alias
;
822 /* Returns true if there is a anti-dependence for the STORE that
823 executes after the LOAD. */
826 refs_anti_dependent_p (tree load
, tree store
)
829 ao_ref_init (&r1
, load
);
830 ao_ref_init (&r2
, store
);
831 return refs_may_alias_p_1 (&r1
, &r2
, false);
834 /* Returns true if there is a output dependence for the stores
835 STORE1 and STORE2. */
838 refs_output_dependent_p (tree store1
, tree store2
)
841 ao_ref_init (&r1
, store1
);
842 ao_ref_init (&r2
, store2
);
843 return refs_may_alias_p_1 (&r1
, &r2
, false);
846 /* If the call CALL may use the memory reference REF return true,
847 otherwise return false. */
850 ref_maybe_used_by_call_p_1 (gimple call
, tree ref
)
854 int flags
= gimple_call_flags (call
);
856 /* Const functions without a static chain do not implicitly use memory. */
857 if (!gimple_call_chain (call
)
858 && (flags
& (ECF_CONST
|ECF_NOVOPS
)))
861 /* If the reference is not based on a decl give up.
862 ??? Handle indirect references by intersecting the call-used
863 solution with that of the pointer. */
864 base
= get_base_address (ref
);
869 /* If the reference is based on a decl that is not aliased the call
870 cannot possibly use it. */
872 && !may_be_aliased (base
)
873 /* But local statics can be used through recursion. */
874 && !is_global_var (base
))
877 callee
= gimple_call_fndecl (call
);
879 /* Handle those builtin functions explicitly that do not act as
880 escape points. See tree-ssa-structalias.c:find_func_aliases
881 for the list of builtins we might need to handle here. */
882 if (callee
!= NULL_TREE
883 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
)
884 switch (DECL_FUNCTION_CODE (callee
))
886 /* All the following functions clobber memory pointed to by
887 their first argument. */
888 case BUILT_IN_STRCPY
:
889 case BUILT_IN_STRNCPY
:
891 case BUILT_IN_MEMCPY
:
892 case BUILT_IN_MEMMOVE
:
893 case BUILT_IN_MEMPCPY
:
894 case BUILT_IN_STPCPY
:
895 case BUILT_IN_STPNCPY
:
896 case BUILT_IN_STRCAT
:
897 case BUILT_IN_STRNCAT
:
899 tree src
= gimple_call_arg (call
, 1);
900 return ptr_deref_may_alias_ref_p (src
, ref
);
903 /* Fallthru to general call handling. */;
906 /* Check if base is a global static variable that is not read
908 if (TREE_CODE (base
) == VAR_DECL
909 && TREE_STATIC (base
)
910 && !TREE_PUBLIC (base
))
914 if (callee
!= NULL_TREE
916 = ipa_reference_get_not_read_global (cgraph_node (callee
)))
917 && bitmap_bit_p (not_read
, DECL_UID (base
)))
921 /* If the base variable is call-used or call-clobbered then
923 if (flags
& (ECF_PURE
|ECF_CONST
|ECF_LOOPING_CONST_OR_PURE
|ECF_NOVOPS
))
925 if (is_call_used (base
))
930 if (is_call_clobbered (base
))
934 /* Inspect call arguments for passed-by-value aliases. */
936 for (i
= 0; i
< gimple_call_num_args (call
); ++i
)
938 tree op
= gimple_call_arg (call
, i
);
940 if (TREE_CODE (op
) == EXC_PTR_EXPR
941 || TREE_CODE (op
) == FILTER_EXPR
)
944 if (TREE_CODE (op
) == WITH_SIZE_EXPR
)
945 op
= TREE_OPERAND (op
, 0);
947 if (TREE_CODE (op
) != SSA_NAME
948 && !is_gimple_min_invariant (op
)
949 && refs_may_alias_p (op
, ref
))
957 ref_maybe_used_by_call_p (gimple call
, tree ref
)
959 bool res
= ref_maybe_used_by_call_p_1 (call
, ref
);
961 ++alias_stats
.ref_maybe_used_by_call_p_may_alias
;
963 ++alias_stats
.ref_maybe_used_by_call_p_no_alias
;
968 /* If the statement STMT may use the memory reference REF return
969 true, otherwise return false. */
972 ref_maybe_used_by_stmt_p (gimple stmt
, tree ref
)
974 if (is_gimple_assign (stmt
))
978 /* All memory assign statements are single. */
979 if (!gimple_assign_single_p (stmt
))
982 rhs
= gimple_assign_rhs1 (stmt
);
983 if (is_gimple_reg (rhs
)
984 || is_gimple_min_invariant (rhs
)
985 || gimple_assign_rhs_code (stmt
) == CONSTRUCTOR
)
988 return refs_may_alias_p (rhs
, ref
);
990 else if (is_gimple_call (stmt
))
991 return ref_maybe_used_by_call_p (stmt
, ref
);
996 /* If the call in statement CALL may clobber the memory reference REF
997 return true, otherwise return false. */
1000 call_may_clobber_ref_p_1 (gimple call
, ao_ref
*ref
)
1005 /* If the call is pure or const it cannot clobber anything. */
1006 if (gimple_call_flags (call
)
1007 & (ECF_PURE
|ECF_CONST
|ECF_LOOPING_CONST_OR_PURE
|ECF_NOVOPS
))
1010 base
= ao_ref_base (ref
);
1014 if (TREE_CODE (base
) == SSA_NAME
1015 || CONSTANT_CLASS_P (base
))
1018 /* If the reference is based on a decl that is not aliased the call
1019 cannot possibly clobber it. */
1021 && !may_be_aliased (base
)
1022 /* But local non-readonly statics can be modified through recursion
1023 or the call may implement a threading barrier which we must
1024 treat as may-def. */
1025 && (TREE_READONLY (base
)
1026 || !is_global_var (base
)))
1029 callee
= gimple_call_fndecl (call
);
1031 /* Handle those builtin functions explicitly that do not act as
1032 escape points. See tree-ssa-structalias.c:find_func_aliases
1033 for the list of builtins we might need to handle here. */
1034 if (callee
!= NULL_TREE
1035 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
)
1036 switch (DECL_FUNCTION_CODE (callee
))
1038 /* All the following functions clobber memory pointed to by
1039 their first argument. */
1040 case BUILT_IN_STRCPY
:
1041 case BUILT_IN_STRNCPY
:
1042 case BUILT_IN_BCOPY
:
1043 case BUILT_IN_MEMCPY
:
1044 case BUILT_IN_MEMMOVE
:
1045 case BUILT_IN_MEMPCPY
:
1046 case BUILT_IN_STPCPY
:
1047 case BUILT_IN_STPNCPY
:
1048 case BUILT_IN_STRCAT
:
1049 case BUILT_IN_STRNCAT
:
1051 tree dest
= gimple_call_arg (call
, 0);
1052 return ptr_deref_may_alias_ref_p_1 (dest
, ref
);
1054 /* Freeing memory kills the pointed-to memory. More importantly
1055 the call has to serve as a barrier for moving loads and stores
1056 across it. Same is true for memset. */
1058 case BUILT_IN_MEMSET
:
1060 tree ptr
= gimple_call_arg (call
, 0);
1061 return ptr_deref_may_alias_ref_p_1 (ptr
, ref
);
1063 case BUILT_IN_FREXP
:
1064 case BUILT_IN_FREXPF
:
1065 case BUILT_IN_FREXPL
:
1066 case BUILT_IN_GAMMA_R
:
1067 case BUILT_IN_GAMMAF_R
:
1068 case BUILT_IN_GAMMAL_R
:
1069 case BUILT_IN_LGAMMA_R
:
1070 case BUILT_IN_LGAMMAF_R
:
1071 case BUILT_IN_LGAMMAL_R
:
1073 case BUILT_IN_MODFF
:
1074 case BUILT_IN_MODFL
:
1076 tree out
= gimple_call_arg (call
, 1);
1077 return ptr_deref_may_alias_ref_p_1 (out
, ref
);
1079 case BUILT_IN_REMQUO
:
1080 case BUILT_IN_REMQUOF
:
1081 case BUILT_IN_REMQUOL
:
1083 tree out
= gimple_call_arg (call
, 2);
1084 return ptr_deref_may_alias_ref_p_1 (out
, ref
);
1086 case BUILT_IN_SINCOS
:
1087 case BUILT_IN_SINCOSF
:
1088 case BUILT_IN_SINCOSL
:
1090 tree sin
= gimple_call_arg (call
, 1);
1091 tree cos
= gimple_call_arg (call
, 2);
1092 return (ptr_deref_may_alias_ref_p_1 (sin
, ref
)
1093 || ptr_deref_may_alias_ref_p_1 (cos
, ref
));
1096 /* Fallthru to general call handling. */;
1099 /* Check if base is a global static variable that is not written
1101 if (callee
!= NULL_TREE
1102 && TREE_CODE (base
) == VAR_DECL
1103 && TREE_STATIC (base
)
1104 && !TREE_PUBLIC (base
))
1109 = ipa_reference_get_not_written_global (cgraph_node (callee
)))
1110 && bitmap_bit_p (not_written
, DECL_UID (base
)))
1115 return is_call_clobbered (base
);
1120 static bool ATTRIBUTE_UNUSED
1121 call_may_clobber_ref_p (gimple call
, tree ref
)
1125 ao_ref_init (&r
, ref
);
1126 res
= call_may_clobber_ref_p_1 (call
, &r
);
1128 ++alias_stats
.call_may_clobber_ref_p_may_alias
;
1130 ++alias_stats
.call_may_clobber_ref_p_no_alias
;
1135 /* If the statement STMT may clobber the memory reference REF return true,
1136 otherwise return false. */
1139 stmt_may_clobber_ref_p_1 (gimple stmt
, ao_ref
*ref
)
1141 if (is_gimple_call (stmt
))
1143 tree lhs
= gimple_call_lhs (stmt
);
1145 && !is_gimple_reg (lhs
))
1148 ao_ref_init (&r
, lhs
);
1149 if (refs_may_alias_p_1 (ref
, &r
, true))
1153 return call_may_clobber_ref_p_1 (stmt
, ref
);
1155 else if (is_gimple_assign (stmt
))
1158 ao_ref_init (&r
, gimple_assign_lhs (stmt
));
1159 return refs_may_alias_p_1 (ref
, &r
, true);
1161 else if (gimple_code (stmt
) == GIMPLE_ASM
)
1168 stmt_may_clobber_ref_p (gimple stmt
, tree ref
)
1171 ao_ref_init (&r
, ref
);
1172 return stmt_may_clobber_ref_p_1 (stmt
, &r
);
1176 static tree
get_continuation_for_phi (gimple
, ao_ref
*, bitmap
*);
1178 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand
1179 TARGET or a statement clobbering the memory reference REF in which
1180 case false is returned. The walk starts with VUSE, one argument of PHI. */
1183 maybe_skip_until (gimple phi
, tree target
, ao_ref
*ref
,
1184 tree vuse
, bitmap
*visited
)
1187 *visited
= BITMAP_ALLOC (NULL
);
1189 bitmap_set_bit (*visited
, SSA_NAME_VERSION (PHI_RESULT (phi
)));
1191 /* Walk until we hit the target. */
1192 while (vuse
!= target
)
1194 gimple def_stmt
= SSA_NAME_DEF_STMT (vuse
);
1195 /* Recurse for PHI nodes. */
1196 if (gimple_code (def_stmt
) == GIMPLE_PHI
)
1198 /* An already visited PHI node ends the walk successfully. */
1199 if (bitmap_bit_p (*visited
, SSA_NAME_VERSION (PHI_RESULT (def_stmt
))))
1201 vuse
= get_continuation_for_phi (def_stmt
, ref
, visited
);
1206 /* A clobbering statement or the end of the IL ends it failing. */
1207 else if (gimple_nop_p (def_stmt
)
1208 || stmt_may_clobber_ref_p_1 (def_stmt
, ref
))
1210 vuse
= gimple_vuse (def_stmt
);
1215 /* Starting from a PHI node for the virtual operand of the memory reference
1216 REF find a continuation virtual operand that allows to continue walking
1217 statements dominating PHI skipping only statements that cannot possibly
1218 clobber REF. Returns NULL_TREE if no suitable virtual operand can
1222 get_continuation_for_phi (gimple phi
, ao_ref
*ref
, bitmap
*visited
)
1224 unsigned nargs
= gimple_phi_num_args (phi
);
1226 /* Through a single-argument PHI we can simply look through. */
1228 return PHI_ARG_DEF (phi
, 0);
1230 /* For two arguments try to skip non-aliasing code until we hit
1231 the phi argument definition that dominates the other one. */
1234 tree arg0
= PHI_ARG_DEF (phi
, 0);
1235 tree arg1
= PHI_ARG_DEF (phi
, 1);
1236 gimple def0
= SSA_NAME_DEF_STMT (arg0
);
1237 gimple def1
= SSA_NAME_DEF_STMT (arg1
);
1241 else if (gimple_nop_p (def0
)
1242 || (!gimple_nop_p (def1
)
1243 && dominated_by_p (CDI_DOMINATORS
,
1244 gimple_bb (def1
), gimple_bb (def0
))))
1246 if (maybe_skip_until (phi
, arg0
, ref
, arg1
, visited
))
1249 else if (gimple_nop_p (def1
)
1250 || dominated_by_p (CDI_DOMINATORS
,
1251 gimple_bb (def0
), gimple_bb (def1
)))
1253 if (maybe_skip_until (phi
, arg1
, ref
, arg0
, visited
))
1261 /* Based on the memory reference REF and its virtual use VUSE call
1262 WALKER for each virtual use that is equivalent to VUSE, including VUSE
1263 itself. That is, for each virtual use for which its defining statement
1264 does not clobber REF.
1266 WALKER is called with REF, the current virtual use and DATA. If
1267 WALKER returns non-NULL the walk stops and its result is returned.
1268 At the end of a non-successful walk NULL is returned.
1270 TRANSLATE if non-NULL is called with a pointer to REF, the virtual
1271 use which definition is a statement that may clobber REF and DATA.
1272 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
1273 If TRANSLATE returns non-NULL the walk stops and its result is returned.
1274 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
1275 to adjust REF and *DATA to make that valid.
1277 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
1280 walk_non_aliased_vuses (ao_ref
*ref
, tree vuse
,
1281 void *(*walker
)(ao_ref
*, tree
, void *),
1282 void *(*translate
)(ao_ref
*, tree
, void *), void *data
)
1284 bitmap visited
= NULL
;
1287 timevar_push (TV_ALIAS_STMT_WALK
);
1293 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1294 res
= (*walker
) (ref
, vuse
, data
);
1298 def_stmt
= SSA_NAME_DEF_STMT (vuse
);
1299 if (gimple_nop_p (def_stmt
))
1301 else if (gimple_code (def_stmt
) == GIMPLE_PHI
)
1302 vuse
= get_continuation_for_phi (def_stmt
, ref
, &visited
);
1305 if (stmt_may_clobber_ref_p_1 (def_stmt
, ref
))
1309 res
= (*translate
) (ref
, vuse
, data
);
1310 /* Failed lookup and translation. */
1311 if (res
== (void *)-1)
1316 /* Lookup succeeded. */
1317 else if (res
!= NULL
)
1319 /* Translation succeeded, continue walking. */
1321 vuse
= gimple_vuse (def_stmt
);
1327 BITMAP_FREE (visited
);
1329 timevar_pop (TV_ALIAS_STMT_WALK
);
1335 /* Based on the memory reference REF call WALKER for each vdef which
1336 defining statement may clobber REF, starting with VDEF. If REF
1337 is NULL_TREE, each defining statement is visited.
1339 WALKER is called with REF, the current vdef and DATA. If WALKER
1340 returns true the walk is stopped, otherwise it continues.
1342 At PHI nodes walk_aliased_vdefs forks into one walk for reach
1343 PHI argument (but only one walk continues on merge points), the
1344 return value is true if any of the walks was successful.
1346 The function returns the number of statements walked. */
1349 walk_aliased_vdefs_1 (tree ref
, tree vdef
,
1350 bool (*walker
)(tree
, tree
, void *), void *data
,
1351 bitmap
*visited
, unsigned int cnt
)
1355 gimple def_stmt
= SSA_NAME_DEF_STMT (vdef
);
1358 && !bitmap_set_bit (*visited
, SSA_NAME_VERSION (vdef
)))
1361 if (gimple_nop_p (def_stmt
))
1363 else if (gimple_code (def_stmt
) == GIMPLE_PHI
)
1367 *visited
= BITMAP_ALLOC (NULL
);
1368 for (i
= 0; i
< gimple_phi_num_args (def_stmt
); ++i
)
1369 cnt
+= walk_aliased_vdefs_1 (ref
, gimple_phi_arg_def (def_stmt
, i
),
1370 walker
, data
, visited
, 0);
1374 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1377 || stmt_may_clobber_ref_p (def_stmt
, ref
))
1378 && (*walker
) (ref
, vdef
, data
))
1381 vdef
= gimple_vuse (def_stmt
);
1387 walk_aliased_vdefs (tree ref
, tree vdef
,
1388 bool (*walker
)(tree
, tree
, void *), void *data
,
1391 bitmap local_visited
= NULL
;
1394 timevar_push (TV_ALIAS_STMT_WALK
);
1396 ret
= walk_aliased_vdefs_1 (ref
, vdef
, walker
, data
,
1397 visited
? visited
: &local_visited
, 0);
1399 BITMAP_FREE (local_visited
);
1401 timevar_pop (TV_ALIAS_STMT_WALK
);