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
, tree type1
,
598 alias_set_type ref1_alias_set
,
599 alias_set_type base1_alias_set
,
600 HOST_WIDE_INT offset1
, HOST_WIDE_INT max_size1
,
601 tree ref2
, tree type2
,
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. */
616 /* Now search for the type1 in the access path of ref2. This
617 would be a common base for doing offset based disambiguation on. */
619 while (handled_component_p (*refp
)
620 && same_type_for_tbaa (TREE_TYPE (*refp
), type1
) == 0)
621 refp
= &TREE_OPERAND (*refp
, 0);
622 same_p
= same_type_for_tbaa (TREE_TYPE (*refp
), type1
);
623 /* If we couldn't compare types we have to bail out. */
626 else if (same_p
== 1)
628 HOST_WIDE_INT offadj
, sztmp
, msztmp
;
629 get_ref_base_and_extent (*refp
, &offadj
, &sztmp
, &msztmp
);
631 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
633 /* If we didn't find a common base, try the other way around. */
635 while (handled_component_p (*refp
)
636 && same_type_for_tbaa (TREE_TYPE (*refp
), type2
) == 0)
637 refp
= &TREE_OPERAND (*refp
, 0);
638 same_p
= same_type_for_tbaa (TREE_TYPE (*refp
), type2
);
639 /* If we couldn't compare types we have to bail out. */
642 else if (same_p
== 1)
644 HOST_WIDE_INT offadj
, sztmp
, msztmp
;
645 get_ref_base_and_extent (*refp
, &offadj
, &sztmp
, &msztmp
);
647 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
650 /* If we have two type access paths B1.path1 and B2.path2 they may
651 only alias if either B1 is in B2.path2 or B2 is in B1.path1.
652 But we can still have a path that goes B1.path1...B2.path2 with
653 a part that we do not see. So we can only disambiguate now
654 if there is no B2 in the tail of path1 and no B1 on the
656 if (base1_alias_set
== ref2_alias_set
657 || alias_set_subset_of (base1_alias_set
, ref2_alias_set
))
659 /* If this is ptr vs. decl then we know there is no ptr ... decl path. */
661 return (base2_alias_set
== ref1_alias_set
662 || alias_set_subset_of (base2_alias_set
, ref1_alias_set
));
666 /* Return true if two memory references based on the variables BASE1
667 and BASE2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
668 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. */
671 decl_refs_may_alias_p (tree base1
,
672 HOST_WIDE_INT offset1
, HOST_WIDE_INT max_size1
,
674 HOST_WIDE_INT offset2
, HOST_WIDE_INT max_size2
)
676 gcc_assert (SSA_VAR_P (base1
) && SSA_VAR_P (base2
));
678 /* If both references are based on different variables, they cannot alias. */
682 /* If both references are based on the same variable, they cannot alias if
683 the accesses do not overlap. */
684 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
687 /* Return true if an indirect reference based on *PTR1 constrained
688 to [OFFSET1, OFFSET1 + MAX_SIZE1) may alias a variable based on BASE2
689 constrained to [OFFSET2, OFFSET2 + MAX_SIZE2). *PTR1 and BASE2 have
690 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
691 in which case they are computed on-demand. REF1 and REF2
692 if non-NULL are the complete memory reference trees. */
695 indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED
, tree base1
,
696 HOST_WIDE_INT offset1
,
697 HOST_WIDE_INT max_size1 ATTRIBUTE_UNUSED
,
698 alias_set_type ref1_alias_set
,
699 alias_set_type base1_alias_set
,
700 tree ref2 ATTRIBUTE_UNUSED
, tree base2
,
701 HOST_WIDE_INT offset2
, HOST_WIDE_INT max_size2
,
702 alias_set_type ref2_alias_set
,
703 alias_set_type base2_alias_set
, bool tbaa_p
)
707 HOST_WIDE_INT offset1p
= offset1
, offset2p
= offset2
;
709 ptr1
= TREE_OPERAND (base1
, 0);
711 /* The offset embedded in MEM_REFs can be negative. Bias them
712 so that the resulting offset adjustment is positive. */
713 if (TREE_CODE (base1
) == MEM_REF
714 || TREE_CODE (base1
) == TARGET_MEM_REF
)
716 double_int moff
= mem_ref_offset (base1
);
717 moff
= double_int_lshift (moff
,
719 ? 3 : exact_log2 (BITS_PER_UNIT
),
720 HOST_BITS_PER_DOUBLE_INT
, true);
721 if (double_int_negative_p (moff
))
722 offset2p
+= double_int_neg (moff
).low
;
724 offset1p
+= moff
.low
;
727 /* If only one reference is based on a variable, they cannot alias if
728 the pointer access is beyond the extent of the variable access.
729 (the pointer base cannot validly point to an offset less than zero
731 They also cannot alias if the pointer may not point to the decl. */
732 if ((TREE_CODE (base1
) != TARGET_MEM_REF
733 || (!TMR_INDEX (base1
) && !TMR_INDEX2 (base1
)))
734 && !ranges_overlap_p (MAX (0, offset1p
), -1, offset2p
, max_size2
))
736 if (!ptr_deref_may_alias_decl_p (ptr1
, base2
))
739 /* Disambiguations that rely on strict aliasing rules follow. */
740 if (!flag_strict_aliasing
|| !tbaa_p
)
743 if (TREE_CODE (base1
) == MEM_REF
)
744 ptrtype1
= TREE_TYPE (TREE_OPERAND (base1
, 1));
745 else if (TREE_CODE (base1
) == TARGET_MEM_REF
)
746 ptrtype1
= TREE_TYPE (TMR_OFFSET (base1
));
748 ptrtype1
= TREE_TYPE (ptr1
);
750 /* If the alias set for a pointer access is zero all bets are off. */
751 if (base1_alias_set
== -1)
752 base1_alias_set
= get_deref_alias_set (ptrtype1
);
753 if (base1_alias_set
== 0)
755 if (base2_alias_set
== -1)
756 base2_alias_set
= get_alias_set (base2
);
758 /* If both references are through the same type, they do not alias
759 if the accesses do not overlap. This does extra disambiguation
760 for mixed/pointer accesses but requires strict aliasing.
761 For MEM_REFs we require that the component-ref offset we computed
762 is relative to the start of the type which we ensure by
763 comparing rvalue and access type and disregarding the constant
765 if ((TREE_CODE (base1
) != TARGET_MEM_REF
766 || (!TMR_INDEX (base1
) && !TMR_INDEX2 (base1
)))
767 && (TREE_CODE (base1
) != MEM_REF
768 || same_type_for_tbaa (TREE_TYPE (base1
), TREE_TYPE (ptrtype1
)) == 1)
769 && same_type_for_tbaa (TREE_TYPE (ptrtype1
), TREE_TYPE (base2
)) == 1)
770 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
772 /* When we are trying to disambiguate an access with a pointer dereference
773 as base versus one with a decl as base we can use both the size
774 of the decl and its dynamic type for extra disambiguation.
775 ??? We do not know anything about the dynamic type of the decl
776 other than that its alias-set contains base2_alias_set as a subset
777 which does not help us here. */
778 /* As we know nothing useful about the dynamic type of the decl just
779 use the usual conflict check rather than a subset test.
780 ??? We could introduce -fvery-strict-aliasing when the language
781 does not allow decls to have a dynamic type that differs from their
782 static type. Then we can check
783 !alias_set_subset_of (base1_alias_set, base2_alias_set) instead. */
784 if (base1_alias_set
!= base2_alias_set
785 && !alias_sets_conflict_p (base1_alias_set
, base2_alias_set
))
787 /* If the size of the access relevant for TBAA through the pointer
788 is bigger than the size of the decl we can't possibly access the
789 decl via that pointer. */
790 if (DECL_SIZE (base2
) && COMPLETE_TYPE_P (TREE_TYPE (ptrtype1
))
791 && TREE_CODE (DECL_SIZE (base2
)) == INTEGER_CST
792 && TREE_CODE (TYPE_SIZE (TREE_TYPE (ptrtype1
))) == INTEGER_CST
793 /* ??? This in turn may run afoul when a decl of type T which is
794 a member of union type U is accessed through a pointer to
795 type U and sizeof T is smaller than sizeof U. */
796 && TREE_CODE (TREE_TYPE (ptrtype1
)) != UNION_TYPE
797 && TREE_CODE (TREE_TYPE (ptrtype1
)) != QUAL_UNION_TYPE
798 && tree_int_cst_lt (DECL_SIZE (base2
), TYPE_SIZE (TREE_TYPE (ptrtype1
))))
801 /* Do access-path based disambiguation. */
803 && handled_component_p (ref1
)
804 && handled_component_p (ref2
)
805 && TREE_CODE (base1
) != TARGET_MEM_REF
806 && (TREE_CODE (base1
) != MEM_REF
807 || same_type_for_tbaa (TREE_TYPE (base1
), TREE_TYPE (ptrtype1
)) == 1))
808 return aliasing_component_refs_p (ref1
, TREE_TYPE (ptrtype1
),
809 ref1_alias_set
, base1_alias_set
,
812 (reference_alias_ptr_type (ref2
)),
813 ref2_alias_set
, base2_alias_set
,
814 offset2
, max_size2
, true);
819 /* Return true if two indirect references based on *PTR1
820 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
821 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have
822 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
823 in which case they are computed on-demand. REF1 and REF2
824 if non-NULL are the complete memory reference trees. */
827 indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED
, tree base1
,
828 HOST_WIDE_INT offset1
, HOST_WIDE_INT max_size1
,
829 alias_set_type ref1_alias_set
,
830 alias_set_type base1_alias_set
,
831 tree ref2 ATTRIBUTE_UNUSED
, tree base2
,
832 HOST_WIDE_INT offset2
, HOST_WIDE_INT max_size2
,
833 alias_set_type ref2_alias_set
,
834 alias_set_type base2_alias_set
, bool tbaa_p
)
838 tree ptrtype1
, ptrtype2
;
840 ptr1
= TREE_OPERAND (base1
, 0);
841 ptr2
= TREE_OPERAND (base2
, 0);
843 /* If both bases are based on pointers they cannot alias if they may not
844 point to the same memory object or if they point to the same object
845 and the accesses do not overlap. */
846 if ((!cfun
|| gimple_in_ssa_p (cfun
))
847 && operand_equal_p (ptr1
, ptr2
, 0)
848 && (((TREE_CODE (base1
) != TARGET_MEM_REF
849 || (!TMR_INDEX (base1
) && !TMR_INDEX2 (base1
)))
850 && (TREE_CODE (base2
) != TARGET_MEM_REF
851 || (!TMR_INDEX (base2
) && !TMR_INDEX2 (base2
))))
852 || (TREE_CODE (base1
) == TARGET_MEM_REF
853 && TREE_CODE (base2
) == TARGET_MEM_REF
854 && (TMR_STEP (base1
) == TMR_STEP (base2
)
855 || (TMR_STEP (base1
) && TMR_STEP (base2
)
856 && operand_equal_p (TMR_STEP (base1
),
857 TMR_STEP (base2
), 0)))
858 && (TMR_INDEX (base1
) == TMR_INDEX (base2
)
859 || (TMR_INDEX (base1
) && TMR_INDEX (base2
)
860 && operand_equal_p (TMR_INDEX (base1
),
861 TMR_INDEX (base2
), 0)))
862 && (TMR_INDEX2 (base1
) == TMR_INDEX2 (base2
)
863 || (TMR_INDEX2 (base1
) && TMR_INDEX2 (base2
)
864 && operand_equal_p (TMR_INDEX2 (base1
),
865 TMR_INDEX2 (base2
), 0))))))
867 /* The offset embedded in MEM_REFs can be negative. Bias them
868 so that the resulting offset adjustment is positive. */
869 if (TREE_CODE (base1
) == MEM_REF
870 || TREE_CODE (base1
) == TARGET_MEM_REF
)
872 double_int moff
= mem_ref_offset (base1
);
873 moff
= double_int_lshift (moff
,
875 ? 3 : exact_log2 (BITS_PER_UNIT
),
876 HOST_BITS_PER_DOUBLE_INT
, true);
877 if (double_int_negative_p (moff
))
878 offset2
+= double_int_neg (moff
).low
;
882 if (TREE_CODE (base2
) == MEM_REF
883 || TREE_CODE (base2
) == TARGET_MEM_REF
)
885 double_int moff
= mem_ref_offset (base2
);
886 moff
= double_int_lshift (moff
,
888 ? 3 : exact_log2 (BITS_PER_UNIT
),
889 HOST_BITS_PER_DOUBLE_INT
, true);
890 if (double_int_negative_p (moff
))
891 offset1
+= double_int_neg (moff
).low
;
895 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
897 if (!ptr_derefs_may_alias_p (ptr1
, ptr2
))
900 /* Disambiguations that rely on strict aliasing rules follow. */
901 if (!flag_strict_aliasing
|| !tbaa_p
)
904 if (TREE_CODE (base1
) == MEM_REF
)
905 ptrtype1
= TREE_TYPE (TREE_OPERAND (base1
, 1));
906 else if (TREE_CODE (base1
) == TARGET_MEM_REF
)
907 ptrtype1
= TREE_TYPE (TMR_OFFSET (base1
));
909 ptrtype1
= TREE_TYPE (ptr1
);
910 if (TREE_CODE (base2
) == MEM_REF
)
911 ptrtype2
= TREE_TYPE (TREE_OPERAND (base2
, 1));
912 else if (TREE_CODE (base2
) == TARGET_MEM_REF
)
913 ptrtype2
= TREE_TYPE (TMR_OFFSET (base2
));
915 ptrtype2
= TREE_TYPE (ptr2
);
917 /* If the alias set for a pointer access is zero all bets are off. */
918 if (base1_alias_set
== -1)
919 base1_alias_set
= get_deref_alias_set (ptrtype1
);
920 if (base1_alias_set
== 0)
922 if (base2_alias_set
== -1)
923 base2_alias_set
= get_deref_alias_set (ptrtype2
);
924 if (base2_alias_set
== 0)
927 /* If both references are through the same type, they do not alias
928 if the accesses do not overlap. This does extra disambiguation
929 for mixed/pointer accesses but requires strict aliasing. */
930 if ((TREE_CODE (base1
) != TARGET_MEM_REF
|| !TMR_INDEX (base1
))
931 && (TREE_CODE (base2
) != TARGET_MEM_REF
|| !TMR_INDEX (base2
))
932 && (TREE_CODE (base1
) != MEM_REF
933 || same_type_for_tbaa (TREE_TYPE (base1
), TREE_TYPE (ptrtype1
)) == 1)
934 && (TREE_CODE (base2
) != MEM_REF
935 || same_type_for_tbaa (TREE_TYPE (base2
), TREE_TYPE (ptrtype2
)) == 1)
936 && same_type_for_tbaa (TREE_TYPE (ptrtype1
),
937 TREE_TYPE (ptrtype2
)) == 1)
938 return ranges_overlap_p (offset1
, max_size1
, offset2
, max_size2
);
940 /* Do type-based disambiguation. */
941 if (base1_alias_set
!= base2_alias_set
942 && !alias_sets_conflict_p (base1_alias_set
, base2_alias_set
))
945 /* Do access-path based disambiguation. */
947 && handled_component_p (ref1
)
948 && handled_component_p (ref2
)
949 && TREE_CODE (base1
) != TARGET_MEM_REF
950 && TREE_CODE (base2
) != TARGET_MEM_REF
951 && (TREE_CODE (base1
) != MEM_REF
952 || same_type_for_tbaa (TREE_TYPE (base1
), TREE_TYPE (ptrtype1
)) == 1)
953 && (TREE_CODE (base2
) != MEM_REF
954 || same_type_for_tbaa (TREE_TYPE (base2
), TREE_TYPE (ptrtype2
)) == 1))
955 return aliasing_component_refs_p (ref1
, TREE_TYPE (ptrtype1
),
956 ref1_alias_set
, base1_alias_set
,
958 ref2
, TREE_TYPE (ptrtype2
),
959 ref2_alias_set
, base2_alias_set
,
960 offset2
, max_size2
, false);
965 /* Return true, if the two memory references REF1 and REF2 may alias. */
968 refs_may_alias_p_1 (ao_ref
*ref1
, ao_ref
*ref2
, bool tbaa_p
)
971 HOST_WIDE_INT offset1
= 0, offset2
= 0;
972 HOST_WIDE_INT max_size1
= -1, max_size2
= -1;
973 bool var1_p
, var2_p
, ind1_p
, ind2_p
;
975 gcc_checking_assert ((!ref1
->ref
976 || TREE_CODE (ref1
->ref
) == SSA_NAME
977 || DECL_P (ref1
->ref
)
978 || TREE_CODE (ref1
->ref
) == STRING_CST
979 || handled_component_p (ref1
->ref
)
980 || INDIRECT_REF_P (ref1
->ref
)
981 || TREE_CODE (ref1
->ref
) == MEM_REF
982 || TREE_CODE (ref1
->ref
) == TARGET_MEM_REF
)
984 || TREE_CODE (ref2
->ref
) == SSA_NAME
985 || DECL_P (ref2
->ref
)
986 || TREE_CODE (ref2
->ref
) == STRING_CST
987 || handled_component_p (ref2
->ref
)
988 || INDIRECT_REF_P (ref2
->ref
)
989 || TREE_CODE (ref2
->ref
) == MEM_REF
990 || TREE_CODE (ref2
->ref
) == TARGET_MEM_REF
));
992 /* Decompose the references into their base objects and the access. */
993 base1
= ao_ref_base (ref1
);
994 offset1
= ref1
->offset
;
995 max_size1
= ref1
->max_size
;
996 base2
= ao_ref_base (ref2
);
997 offset2
= ref2
->offset
;
998 max_size2
= ref2
->max_size
;
1000 /* We can end up with registers or constants as bases for example from
1001 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
1002 which is seen as a struct copy. */
1003 if (TREE_CODE (base1
) == SSA_NAME
1004 || TREE_CODE (base1
) == CONST_DECL
1005 || TREE_CODE (base1
) == CONSTRUCTOR
1006 || TREE_CODE (base1
) == ADDR_EXPR
1007 || CONSTANT_CLASS_P (base1
)
1008 || TREE_CODE (base2
) == SSA_NAME
1009 || TREE_CODE (base2
) == CONST_DECL
1010 || TREE_CODE (base2
) == CONSTRUCTOR
1011 || TREE_CODE (base2
) == ADDR_EXPR
1012 || CONSTANT_CLASS_P (base2
))
1015 /* We can end up refering to code via function and label decls.
1016 As we likely do not properly track code aliases conservatively
1018 if (TREE_CODE (base1
) == FUNCTION_DECL
1019 || TREE_CODE (base1
) == LABEL_DECL
1020 || TREE_CODE (base2
) == FUNCTION_DECL
1021 || TREE_CODE (base2
) == LABEL_DECL
)
1024 /* Defer to simple offset based disambiguation if we have
1025 references based on two decls. Do this before defering to
1026 TBAA to handle must-alias cases in conformance with the
1027 GCC extension of allowing type-punning through unions. */
1028 var1_p
= SSA_VAR_P (base1
);
1029 var2_p
= SSA_VAR_P (base2
);
1030 if (var1_p
&& var2_p
)
1031 return decl_refs_may_alias_p (base1
, offset1
, max_size1
,
1032 base2
, offset2
, max_size2
);
1034 ind1_p
= (INDIRECT_REF_P (base1
)
1035 || (TREE_CODE (base1
) == MEM_REF
)
1036 || (TREE_CODE (base1
) == TARGET_MEM_REF
));
1037 ind2_p
= (INDIRECT_REF_P (base2
)
1038 || (TREE_CODE (base2
) == MEM_REF
)
1039 || (TREE_CODE (base2
) == TARGET_MEM_REF
));
1041 /* Canonicalize the pointer-vs-decl case. */
1042 if (ind1_p
&& var2_p
)
1047 tmp1
= offset1
; offset1
= offset2
; offset2
= tmp1
;
1048 tmp1
= max_size1
; max_size1
= max_size2
; max_size2
= tmp1
;
1049 tmp2
= base1
; base1
= base2
; base2
= tmp2
;
1050 tmp3
= ref1
; ref1
= ref2
; ref2
= tmp3
;
1057 /* First defer to TBAA if possible. */
1059 && flag_strict_aliasing
1060 && !alias_sets_conflict_p (ao_ref_alias_set (ref1
),
1061 ao_ref_alias_set (ref2
)))
1064 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */
1065 if (var1_p
&& ind2_p
)
1066 return indirect_ref_may_alias_decl_p (ref2
->ref
, base2
,
1068 ao_ref_alias_set (ref2
), -1,
1071 ao_ref_alias_set (ref1
),
1072 ao_ref_base_alias_set (ref1
),
1074 else if (ind1_p
&& ind2_p
)
1075 return indirect_refs_may_alias_p (ref1
->ref
, base1
,
1077 ao_ref_alias_set (ref1
), -1,
1080 ao_ref_alias_set (ref2
), -1,
1087 refs_may_alias_p (tree ref1
, tree ref2
)
1091 ao_ref_init (&r1
, ref1
);
1092 ao_ref_init (&r2
, ref2
);
1093 res
= refs_may_alias_p_1 (&r1
, &r2
, true);
1095 ++alias_stats
.refs_may_alias_p_may_alias
;
1097 ++alias_stats
.refs_may_alias_p_no_alias
;
1101 /* Returns true if there is a anti-dependence for the STORE that
1102 executes after the LOAD. */
1105 refs_anti_dependent_p (tree load
, tree store
)
1108 ao_ref_init (&r1
, load
);
1109 ao_ref_init (&r2
, store
);
1110 return refs_may_alias_p_1 (&r1
, &r2
, false);
1113 /* Returns true if there is a output dependence for the stores
1114 STORE1 and STORE2. */
1117 refs_output_dependent_p (tree store1
, tree store2
)
1120 ao_ref_init (&r1
, store1
);
1121 ao_ref_init (&r2
, store2
);
1122 return refs_may_alias_p_1 (&r1
, &r2
, false);
1125 /* If the call CALL may use the memory reference REF return true,
1126 otherwise return false. */
1129 ref_maybe_used_by_call_p_1 (gimple call
, ao_ref
*ref
)
1133 int flags
= gimple_call_flags (call
);
1135 /* Const functions without a static chain do not implicitly use memory. */
1136 if (!gimple_call_chain (call
)
1137 && (flags
& (ECF_CONST
|ECF_NOVOPS
)))
1140 base
= ao_ref_base (ref
);
1144 /* If the reference is based on a decl that is not aliased the call
1145 cannot possibly use it. */
1147 && !may_be_aliased (base
)
1148 /* But local statics can be used through recursion. */
1149 && !is_global_var (base
))
1152 callee
= gimple_call_fndecl (call
);
1154 /* Handle those builtin functions explicitly that do not act as
1155 escape points. See tree-ssa-structalias.c:find_func_aliases
1156 for the list of builtins we might need to handle here. */
1157 if (callee
!= NULL_TREE
1158 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
)
1159 switch (DECL_FUNCTION_CODE (callee
))
1161 /* All the following functions clobber memory pointed to by
1162 their first argument. */
1163 case BUILT_IN_STRCPY
:
1164 case BUILT_IN_STRNCPY
:
1165 case BUILT_IN_MEMCPY
:
1166 case BUILT_IN_MEMMOVE
:
1167 case BUILT_IN_MEMPCPY
:
1168 case BUILT_IN_STPCPY
:
1169 case BUILT_IN_STPNCPY
:
1170 case BUILT_IN_STRCAT
:
1171 case BUILT_IN_STRNCAT
:
1174 tree size
= NULL_TREE
;
1175 if (gimple_call_num_args (call
) == 3)
1176 size
= gimple_call_arg (call
, 2);
1177 ao_ref_init_from_ptr_and_size (&dref
,
1178 gimple_call_arg (call
, 1),
1180 return refs_may_alias_p_1 (&dref
, ref
, false);
1182 case BUILT_IN_BCOPY
:
1185 tree size
= gimple_call_arg (call
, 2);
1186 ao_ref_init_from_ptr_and_size (&dref
,
1187 gimple_call_arg (call
, 0),
1189 return refs_may_alias_p_1 (&dref
, ref
, false);
1191 /* The following builtins do not read from memory. */
1193 case BUILT_IN_MALLOC
:
1194 case BUILT_IN_CALLOC
:
1195 case BUILT_IN_MEMSET
:
1196 case BUILT_IN_FREXP
:
1197 case BUILT_IN_FREXPF
:
1198 case BUILT_IN_FREXPL
:
1199 case BUILT_IN_GAMMA_R
:
1200 case BUILT_IN_GAMMAF_R
:
1201 case BUILT_IN_GAMMAL_R
:
1202 case BUILT_IN_LGAMMA_R
:
1203 case BUILT_IN_LGAMMAF_R
:
1204 case BUILT_IN_LGAMMAL_R
:
1206 case BUILT_IN_MODFF
:
1207 case BUILT_IN_MODFL
:
1208 case BUILT_IN_REMQUO
:
1209 case BUILT_IN_REMQUOF
:
1210 case BUILT_IN_REMQUOL
:
1211 case BUILT_IN_SINCOS
:
1212 case BUILT_IN_SINCOSF
:
1213 case BUILT_IN_SINCOSL
:
1215 /* __sync_* builtins and some OpenMP builtins act as threading
1217 #undef DEF_SYNC_BUILTIN
1218 #define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM:
1219 #include "sync-builtins.def"
1220 #undef DEF_SYNC_BUILTIN
1221 case BUILT_IN_GOMP_ATOMIC_START
:
1222 case BUILT_IN_GOMP_ATOMIC_END
:
1223 case BUILT_IN_GOMP_BARRIER
:
1224 case BUILT_IN_GOMP_TASKWAIT
:
1225 case BUILT_IN_GOMP_CRITICAL_START
:
1226 case BUILT_IN_GOMP_CRITICAL_END
:
1227 case BUILT_IN_GOMP_CRITICAL_NAME_START
:
1228 case BUILT_IN_GOMP_CRITICAL_NAME_END
:
1229 case BUILT_IN_GOMP_LOOP_END
:
1230 case BUILT_IN_GOMP_ORDERED_START
:
1231 case BUILT_IN_GOMP_ORDERED_END
:
1232 case BUILT_IN_GOMP_PARALLEL_END
:
1233 case BUILT_IN_GOMP_SECTIONS_END
:
1234 case BUILT_IN_GOMP_SINGLE_COPY_START
:
1235 case BUILT_IN_GOMP_SINGLE_COPY_END
:
1239 /* Fallthru to general call handling. */;
1242 /* Check if base is a global static variable that is not read
1244 if (TREE_CODE (base
) == VAR_DECL
1245 && TREE_STATIC (base
))
1249 if (callee
!= NULL_TREE
1251 = ipa_reference_get_not_read_global (cgraph_node (callee
)))
1252 && bitmap_bit_p (not_read
, DECL_UID (base
)))
1256 /* Check if the base variable is call-used. */
1259 if (pt_solution_includes (gimple_call_use_set (call
), base
))
1262 else if ((INDIRECT_REF_P (base
)
1263 || TREE_CODE (base
) == MEM_REF
)
1264 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
1266 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (TREE_OPERAND (base
, 0));
1270 if (pt_solutions_intersect (gimple_call_use_set (call
), &pi
->pt
))
1276 /* Inspect call arguments for passed-by-value aliases. */
1278 for (i
= 0; i
< gimple_call_num_args (call
); ++i
)
1280 tree op
= gimple_call_arg (call
, i
);
1281 int flags
= gimple_call_arg_flags (call
, i
);
1283 if (flags
& EAF_UNUSED
)
1286 if (TREE_CODE (op
) == WITH_SIZE_EXPR
)
1287 op
= TREE_OPERAND (op
, 0);
1289 if (TREE_CODE (op
) != SSA_NAME
1290 && !is_gimple_min_invariant (op
))
1293 ao_ref_init (&r
, op
);
1294 if (refs_may_alias_p_1 (&r
, ref
, true))
1303 ref_maybe_used_by_call_p (gimple call
, tree ref
)
1307 ao_ref_init (&r
, ref
);
1308 res
= ref_maybe_used_by_call_p_1 (call
, &r
);
1310 ++alias_stats
.ref_maybe_used_by_call_p_may_alias
;
1312 ++alias_stats
.ref_maybe_used_by_call_p_no_alias
;
1317 /* If the statement STMT may use the memory reference REF return
1318 true, otherwise return false. */
1321 ref_maybe_used_by_stmt_p (gimple stmt
, tree ref
)
1323 if (is_gimple_assign (stmt
))
1327 /* All memory assign statements are single. */
1328 if (!gimple_assign_single_p (stmt
))
1331 rhs
= gimple_assign_rhs1 (stmt
);
1332 if (is_gimple_reg (rhs
)
1333 || is_gimple_min_invariant (rhs
)
1334 || gimple_assign_rhs_code (stmt
) == CONSTRUCTOR
)
1337 return refs_may_alias_p (rhs
, ref
);
1339 else if (is_gimple_call (stmt
))
1340 return ref_maybe_used_by_call_p (stmt
, ref
);
1345 /* If the call in statement CALL may clobber the memory reference REF
1346 return true, otherwise return false. */
1349 call_may_clobber_ref_p_1 (gimple call
, ao_ref
*ref
)
1354 /* If the call is pure or const it cannot clobber anything. */
1355 if (gimple_call_flags (call
)
1356 & (ECF_PURE
|ECF_CONST
|ECF_LOOPING_CONST_OR_PURE
|ECF_NOVOPS
))
1359 base
= ao_ref_base (ref
);
1363 if (TREE_CODE (base
) == SSA_NAME
1364 || CONSTANT_CLASS_P (base
))
1367 /* If the reference is based on a decl that is not aliased the call
1368 cannot possibly clobber it. */
1370 && !may_be_aliased (base
)
1371 /* But local non-readonly statics can be modified through recursion
1372 or the call may implement a threading barrier which we must
1373 treat as may-def. */
1374 && (TREE_READONLY (base
)
1375 || !is_global_var (base
)))
1378 callee
= gimple_call_fndecl (call
);
1380 /* Handle those builtin functions explicitly that do not act as
1381 escape points. See tree-ssa-structalias.c:find_func_aliases
1382 for the list of builtins we might need to handle here. */
1383 if (callee
!= NULL_TREE
1384 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
)
1385 switch (DECL_FUNCTION_CODE (callee
))
1387 /* All the following functions clobber memory pointed to by
1388 their first argument. */
1389 case BUILT_IN_STRCPY
:
1390 case BUILT_IN_STRNCPY
:
1391 case BUILT_IN_MEMCPY
:
1392 case BUILT_IN_MEMMOVE
:
1393 case BUILT_IN_MEMPCPY
:
1394 case BUILT_IN_STPCPY
:
1395 case BUILT_IN_STPNCPY
:
1396 case BUILT_IN_STRCAT
:
1397 case BUILT_IN_STRNCAT
:
1398 case BUILT_IN_MEMSET
:
1401 tree size
= NULL_TREE
;
1402 if (gimple_call_num_args (call
) == 3)
1403 size
= gimple_call_arg (call
, 2);
1404 ao_ref_init_from_ptr_and_size (&dref
,
1405 gimple_call_arg (call
, 0),
1407 return refs_may_alias_p_1 (&dref
, ref
, false);
1409 case BUILT_IN_BCOPY
:
1412 tree size
= gimple_call_arg (call
, 2);
1413 ao_ref_init_from_ptr_and_size (&dref
,
1414 gimple_call_arg (call
, 1),
1416 return refs_may_alias_p_1 (&dref
, ref
, false);
1418 /* Allocating memory does not have any side-effects apart from
1419 being the definition point for the pointer. */
1420 case BUILT_IN_MALLOC
:
1421 case BUILT_IN_CALLOC
:
1422 /* Unix98 specifies that errno is set on allocation failure. */
1424 && targetm
.ref_may_alias_errno (ref
))
1427 /* Freeing memory kills the pointed-to memory. More importantly
1428 the call has to serve as a barrier for moving loads and stores
1432 tree ptr
= gimple_call_arg (call
, 0);
1433 return ptr_deref_may_alias_ref_p_1 (ptr
, ref
);
1435 case BUILT_IN_GAMMA_R
:
1436 case BUILT_IN_GAMMAF_R
:
1437 case BUILT_IN_GAMMAL_R
:
1438 case BUILT_IN_LGAMMA_R
:
1439 case BUILT_IN_LGAMMAF_R
:
1440 case BUILT_IN_LGAMMAL_R
:
1442 tree out
= gimple_call_arg (call
, 1);
1443 if (ptr_deref_may_alias_ref_p_1 (out
, ref
))
1445 if (flag_errno_math
)
1449 case BUILT_IN_FREXP
:
1450 case BUILT_IN_FREXPF
:
1451 case BUILT_IN_FREXPL
:
1453 case BUILT_IN_MODFF
:
1454 case BUILT_IN_MODFL
:
1456 tree out
= gimple_call_arg (call
, 1);
1457 return ptr_deref_may_alias_ref_p_1 (out
, ref
);
1459 case BUILT_IN_REMQUO
:
1460 case BUILT_IN_REMQUOF
:
1461 case BUILT_IN_REMQUOL
:
1463 tree out
= gimple_call_arg (call
, 2);
1464 if (ptr_deref_may_alias_ref_p_1 (out
, ref
))
1466 if (flag_errno_math
)
1470 case BUILT_IN_SINCOS
:
1471 case BUILT_IN_SINCOSF
:
1472 case BUILT_IN_SINCOSL
:
1474 tree sin
= gimple_call_arg (call
, 1);
1475 tree cos
= gimple_call_arg (call
, 2);
1476 return (ptr_deref_may_alias_ref_p_1 (sin
, ref
)
1477 || ptr_deref_may_alias_ref_p_1 (cos
, ref
));
1479 /* __sync_* builtins and some OpenMP builtins act as threading
1481 #undef DEF_SYNC_BUILTIN
1482 #define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM:
1483 #include "sync-builtins.def"
1484 #undef DEF_SYNC_BUILTIN
1485 case BUILT_IN_GOMP_ATOMIC_START
:
1486 case BUILT_IN_GOMP_ATOMIC_END
:
1487 case BUILT_IN_GOMP_BARRIER
:
1488 case BUILT_IN_GOMP_TASKWAIT
:
1489 case BUILT_IN_GOMP_CRITICAL_START
:
1490 case BUILT_IN_GOMP_CRITICAL_END
:
1491 case BUILT_IN_GOMP_CRITICAL_NAME_START
:
1492 case BUILT_IN_GOMP_CRITICAL_NAME_END
:
1493 case BUILT_IN_GOMP_LOOP_END
:
1494 case BUILT_IN_GOMP_ORDERED_START
:
1495 case BUILT_IN_GOMP_ORDERED_END
:
1496 case BUILT_IN_GOMP_PARALLEL_END
:
1497 case BUILT_IN_GOMP_SECTIONS_END
:
1498 case BUILT_IN_GOMP_SINGLE_COPY_START
:
1499 case BUILT_IN_GOMP_SINGLE_COPY_END
:
1502 /* Fallthru to general call handling. */;
1505 /* Check if base is a global static variable that is not written
1507 if (callee
!= NULL_TREE
1508 && TREE_CODE (base
) == VAR_DECL
1509 && TREE_STATIC (base
))
1514 = ipa_reference_get_not_written_global (cgraph_node (callee
)))
1515 && bitmap_bit_p (not_written
, DECL_UID (base
)))
1519 /* Check if the base variable is call-clobbered. */
1521 return pt_solution_includes (gimple_call_clobber_set (call
), base
);
1522 else if ((INDIRECT_REF_P (base
)
1523 || TREE_CODE (base
) == MEM_REF
)
1524 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
1526 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (TREE_OPERAND (base
, 0));
1530 return pt_solutions_intersect (gimple_call_clobber_set (call
), &pi
->pt
);
1536 /* If the call in statement CALL may clobber the memory reference REF
1537 return true, otherwise return false. */
1540 call_may_clobber_ref_p (gimple call
, tree ref
)
1544 ao_ref_init (&r
, ref
);
1545 res
= call_may_clobber_ref_p_1 (call
, &r
);
1547 ++alias_stats
.call_may_clobber_ref_p_may_alias
;
1549 ++alias_stats
.call_may_clobber_ref_p_no_alias
;
1554 /* If the statement STMT may clobber the memory reference REF return true,
1555 otherwise return false. */
1558 stmt_may_clobber_ref_p_1 (gimple stmt
, ao_ref
*ref
)
1560 if (is_gimple_call (stmt
))
1562 tree lhs
= gimple_call_lhs (stmt
);
1564 && TREE_CODE (lhs
) != SSA_NAME
)
1567 ao_ref_init (&r
, lhs
);
1568 if (refs_may_alias_p_1 (ref
, &r
, true))
1572 return call_may_clobber_ref_p_1 (stmt
, ref
);
1574 else if (gimple_assign_single_p (stmt
))
1576 tree lhs
= gimple_assign_lhs (stmt
);
1577 if (TREE_CODE (lhs
) != SSA_NAME
)
1580 ao_ref_init (&r
, lhs
);
1581 return refs_may_alias_p_1 (ref
, &r
, true);
1584 else if (gimple_code (stmt
) == GIMPLE_ASM
)
1591 stmt_may_clobber_ref_p (gimple stmt
, tree ref
)
1594 ao_ref_init (&r
, ref
);
1595 return stmt_may_clobber_ref_p_1 (stmt
, &r
);
1598 /* If STMT kills the memory reference REF return true, otherwise
1602 stmt_kills_ref_p_1 (gimple stmt
, ao_ref
*ref
)
1604 if (gimple_has_lhs (stmt
)
1605 && TREE_CODE (gimple_get_lhs (stmt
)) != SSA_NAME
)
1607 tree base
, lhs
= gimple_get_lhs (stmt
);
1608 HOST_WIDE_INT size
, offset
, max_size
;
1610 base
= get_ref_base_and_extent (lhs
, &offset
, &size
, &max_size
);
1611 /* We can get MEM[symbol: sZ, index: D.8862_1] here,
1612 so base == ref->base does not always hold. */
1613 if (base
== ref
->base
)
1615 /* For a must-alias check we need to be able to constrain
1616 the accesses properly. */
1617 if (size
!= -1 && size
== max_size
1618 && ref
->max_size
!= -1)
1620 if (offset
<= ref
->offset
1621 && offset
+ size
>= ref
->offset
+ ref
->max_size
)
1630 stmt_kills_ref_p (gimple stmt
, tree ref
)
1633 ao_ref_init (&r
, ref
);
1634 return stmt_kills_ref_p_1 (stmt
, &r
);
1638 /* Walk the virtual use-def chain of VUSE until hitting the virtual operand
1639 TARGET or a statement clobbering the memory reference REF in which
1640 case false is returned. The walk starts with VUSE, one argument of PHI. */
1643 maybe_skip_until (gimple phi
, tree target
, ao_ref
*ref
,
1644 tree vuse
, bitmap
*visited
)
1647 *visited
= BITMAP_ALLOC (NULL
);
1649 bitmap_set_bit (*visited
, SSA_NAME_VERSION (PHI_RESULT (phi
)));
1651 /* Walk until we hit the target. */
1652 while (vuse
!= target
)
1654 gimple def_stmt
= SSA_NAME_DEF_STMT (vuse
);
1655 /* Recurse for PHI nodes. */
1656 if (gimple_code (def_stmt
) == GIMPLE_PHI
)
1658 /* An already visited PHI node ends the walk successfully. */
1659 if (bitmap_bit_p (*visited
, SSA_NAME_VERSION (PHI_RESULT (def_stmt
))))
1661 vuse
= get_continuation_for_phi (def_stmt
, ref
, visited
);
1666 /* A clobbering statement or the end of the IL ends it failing. */
1667 else if (gimple_nop_p (def_stmt
)
1668 || stmt_may_clobber_ref_p_1 (def_stmt
, ref
))
1670 vuse
= gimple_vuse (def_stmt
);
1675 /* Starting from a PHI node for the virtual operand of the memory reference
1676 REF find a continuation virtual operand that allows to continue walking
1677 statements dominating PHI skipping only statements that cannot possibly
1678 clobber REF. Returns NULL_TREE if no suitable virtual operand can
1682 get_continuation_for_phi (gimple phi
, ao_ref
*ref
, bitmap
*visited
)
1684 unsigned nargs
= gimple_phi_num_args (phi
);
1686 /* Through a single-argument PHI we can simply look through. */
1688 return PHI_ARG_DEF (phi
, 0);
1690 /* For two arguments try to skip non-aliasing code until we hit
1691 the phi argument definition that dominates the other one. */
1694 tree arg0
= PHI_ARG_DEF (phi
, 0);
1695 tree arg1
= PHI_ARG_DEF (phi
, 1);
1696 gimple def0
= SSA_NAME_DEF_STMT (arg0
);
1697 gimple def1
= SSA_NAME_DEF_STMT (arg1
);
1702 else if (gimple_nop_p (def0
)
1703 || (!gimple_nop_p (def1
)
1704 && dominated_by_p (CDI_DOMINATORS
,
1705 gimple_bb (def1
), gimple_bb (def0
))))
1707 if (maybe_skip_until (phi
, arg0
, ref
, arg1
, visited
))
1710 else if (gimple_nop_p (def1
)
1711 || dominated_by_p (CDI_DOMINATORS
,
1712 gimple_bb (def0
), gimple_bb (def1
)))
1714 if (maybe_skip_until (phi
, arg1
, ref
, arg0
, visited
))
1717 /* Special case of a diamond:
1719 goto (cond) ? L1 : L2
1720 L1: store1 = ... #MEM_2 = vuse(MEM_1)
1722 L2: store2 = ... #MEM_3 = vuse(MEM_1)
1723 L3: MEM_4 = PHI<MEM_2, MEM_3>
1724 We were called with the PHI at L3, MEM_2 and MEM_3 don't
1725 dominate each other, but still we can easily skip this PHI node
1726 if we recognize that the vuse MEM operand is the same for both,
1727 and that we can skip both statements (they don't clobber us).
1728 This is still linear. Don't use maybe_skip_until, that might
1729 potentially be slow. */
1730 else if ((common_vuse
= gimple_vuse (def0
))
1731 && common_vuse
== gimple_vuse (def1
))
1733 if (!stmt_may_clobber_ref_p_1 (def0
, ref
)
1734 && !stmt_may_clobber_ref_p_1 (def1
, ref
))
1742 /* Based on the memory reference REF and its virtual use VUSE call
1743 WALKER for each virtual use that is equivalent to VUSE, including VUSE
1744 itself. That is, for each virtual use for which its defining statement
1745 does not clobber REF.
1747 WALKER is called with REF, the current virtual use and DATA. If
1748 WALKER returns non-NULL the walk stops and its result is returned.
1749 At the end of a non-successful walk NULL is returned.
1751 TRANSLATE if non-NULL is called with a pointer to REF, the virtual
1752 use which definition is a statement that may clobber REF and DATA.
1753 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
1754 If TRANSLATE returns non-NULL the walk stops and its result is returned.
1755 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
1756 to adjust REF and *DATA to make that valid.
1758 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
1761 walk_non_aliased_vuses (ao_ref
*ref
, tree vuse
,
1762 void *(*walker
)(ao_ref
*, tree
, void *),
1763 void *(*translate
)(ao_ref
*, tree
, void *), void *data
)
1765 bitmap visited
= NULL
;
1768 timevar_push (TV_ALIAS_STMT_WALK
);
1774 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1775 res
= (*walker
) (ref
, vuse
, data
);
1779 def_stmt
= SSA_NAME_DEF_STMT (vuse
);
1780 if (gimple_nop_p (def_stmt
))
1782 else if (gimple_code (def_stmt
) == GIMPLE_PHI
)
1783 vuse
= get_continuation_for_phi (def_stmt
, ref
, &visited
);
1786 if (stmt_may_clobber_ref_p_1 (def_stmt
, ref
))
1790 res
= (*translate
) (ref
, vuse
, data
);
1791 /* Failed lookup and translation. */
1792 if (res
== (void *)-1)
1797 /* Lookup succeeded. */
1798 else if (res
!= NULL
)
1800 /* Translation succeeded, continue walking. */
1802 vuse
= gimple_vuse (def_stmt
);
1808 BITMAP_FREE (visited
);
1810 timevar_pop (TV_ALIAS_STMT_WALK
);
1816 /* Based on the memory reference REF call WALKER for each vdef which
1817 defining statement may clobber REF, starting with VDEF. If REF
1818 is NULL_TREE, each defining statement is visited.
1820 WALKER is called with REF, the current vdef and DATA. If WALKER
1821 returns true the walk is stopped, otherwise it continues.
1823 At PHI nodes walk_aliased_vdefs forks into one walk for reach
1824 PHI argument (but only one walk continues on merge points), the
1825 return value is true if any of the walks was successful.
1827 The function returns the number of statements walked. */
1830 walk_aliased_vdefs_1 (ao_ref
*ref
, tree vdef
,
1831 bool (*walker
)(ao_ref
*, tree
, void *), void *data
,
1832 bitmap
*visited
, unsigned int cnt
)
1836 gimple def_stmt
= SSA_NAME_DEF_STMT (vdef
);
1839 && !bitmap_set_bit (*visited
, SSA_NAME_VERSION (vdef
)))
1842 if (gimple_nop_p (def_stmt
))
1844 else if (gimple_code (def_stmt
) == GIMPLE_PHI
)
1848 *visited
= BITMAP_ALLOC (NULL
);
1849 for (i
= 0; i
< gimple_phi_num_args (def_stmt
); ++i
)
1850 cnt
+= walk_aliased_vdefs_1 (ref
, gimple_phi_arg_def (def_stmt
, i
),
1851 walker
, data
, visited
, 0);
1855 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
1858 || stmt_may_clobber_ref_p_1 (def_stmt
, ref
))
1859 && (*walker
) (ref
, vdef
, data
))
1862 vdef
= gimple_vuse (def_stmt
);
1868 walk_aliased_vdefs (ao_ref
*ref
, tree vdef
,
1869 bool (*walker
)(ao_ref
*, tree
, void *), void *data
,
1872 bitmap local_visited
= NULL
;
1875 timevar_push (TV_ALIAS_STMT_WALK
);
1877 ret
= walk_aliased_vdefs_1 (ref
, vdef
, walker
, data
,
1878 visited
? visited
: &local_visited
, 0);
1880 BITMAP_FREE (local_visited
);
1882 timevar_pop (TV_ALIAS_STMT_WALK
);