1/* Alias analysis for trees.
2 Copyright (C) 2004-2017 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
4
5This file is part of GCC.
6
7GCC is free software; you can redistribute it and/or modify
8it under the terms of the GNU General Public License as published by
9the Free Software Foundation; either version 3, or (at your option)
10any later version.
11
12GCC is distributed in the hope that it will be useful,
13but WITHOUT ANY WARRANTY; without even the implied warranty of
14MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15GNU General Public License for more details.
16
17You should have received a copy of the GNU General Public License
18along with GCC; see the file COPYING3. If not see
19<http://www.gnu.org/licenses/>. */
20
21#include "config.h"
22#include "system.h"
23#include "coretypes.h"
24#include "backend.h"
25#include "target.h"
26#include "rtl.h"
27#include "tree.h"
28#include "gimple.h"
29#include "timevar.h" /* for TV_ALIAS_STMT_WALK */
30#include "ssa.h"
31#include "cgraph.h"
32#include "tree-pretty-print.h"
33#include "alias.h"
34#include "fold-const.h"
35#include "langhooks.h"
36#include "dumpfile.h"
37#include "tree-eh.h"
38#include "tree-dfa.h"
39#include "ipa-reference.h"
40#include "varasm.h"
41
42/* Broad overview of how alias analysis on gimple works:
43
44 Statements clobbering or using memory are linked through the
45 virtual operand factored use-def chain. The virtual operand
46 is unique per function, its symbol is accessible via gimple_vop (cfun).
47 Virtual operands are used for efficiently walking memory statements
48 in the gimple IL and are useful for things like value-numbering as
49 a generation count for memory references.
50
51 SSA_NAME pointers may have associated points-to information
52 accessible via the SSA_NAME_PTR_INFO macro. Flow-insensitive
53 points-to information is (re-)computed by the TODO_rebuild_alias
54 pass manager todo. Points-to information is also used for more
55 precise tracking of call-clobbered and call-used variables and
56 related disambiguations.
57
58 This file contains functions for disambiguating memory references,
59 the so called alias-oracle and tools for walking of the gimple IL.
60
61 The main alias-oracle entry-points are
62
63 bool stmt_may_clobber_ref_p (gimple *, tree)
64
65 This function queries if a statement may invalidate (parts of)
66 the memory designated by the reference tree argument.
67
68 bool ref_maybe_used_by_stmt_p (gimple *, tree)
69
70 This function queries if a statement may need (parts of) the
71 memory designated by the reference tree argument.
72
73 There are variants of these functions that only handle the call
74 part of a statement, call_may_clobber_ref_p and ref_maybe_used_by_call_p.
75 Note that these do not disambiguate against a possible call lhs.
76
77 bool refs_may_alias_p (tree, tree)
78
79 This function tries to disambiguate two reference trees.
80
81 bool ptr_deref_may_alias_global_p (tree)
82
83 This function queries if dereferencing a pointer variable may
84 alias global memory.
85
86 More low-level disambiguators are available and documented in
87 this file. Low-level disambiguators dealing with points-to
88 information are in tree-ssa-structalias.c. */
89
90
91/* Query statistics for the different low-level disambiguators.
92 A high-level query may trigger multiple of them. */
93
94static struct {
95 unsigned HOST_WIDE_INT refs_may_alias_p_may_alias;
96 unsigned HOST_WIDE_INT refs_may_alias_p_no_alias;
97 unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_may_alias;
98 unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_no_alias;
99 unsigned HOST_WIDE_INT call_may_clobber_ref_p_may_alias;
100 unsigned HOST_WIDE_INT call_may_clobber_ref_p_no_alias;
101} alias_stats;
102
103void
104dump_alias_stats (FILE *s)
105{
106 fprintf (s, "\nAlias oracle query stats:\n");
107 fprintf (s, " refs_may_alias_p: "
108 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
109 HOST_WIDE_INT_PRINT_DEC" queries\n",
110 alias_stats.refs_may_alias_p_no_alias,
111 alias_stats.refs_may_alias_p_no_alias
112 + alias_stats.refs_may_alias_p_may_alias);
113 fprintf (s, " ref_maybe_used_by_call_p: "
114 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
115 HOST_WIDE_INT_PRINT_DEC" queries\n",
116 alias_stats.ref_maybe_used_by_call_p_no_alias,
117 alias_stats.refs_may_alias_p_no_alias
118 + alias_stats.ref_maybe_used_by_call_p_may_alias);
119 fprintf (s, " call_may_clobber_ref_p: "
120 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
121 HOST_WIDE_INT_PRINT_DEC" queries\n",
122 alias_stats.call_may_clobber_ref_p_no_alias,
123 alias_stats.call_may_clobber_ref_p_no_alias
124 + alias_stats.call_may_clobber_ref_p_may_alias);
125 dump_alias_stats_in_alias_c (s);
126}
127
128
129/* Return true, if dereferencing PTR may alias with a global variable. */
130
131bool
132ptr_deref_may_alias_global_p (tree ptr)
133{
134 struct ptr_info_def *pi;
135
136 /* If we end up with a pointer constant here that may point
137 to global memory. */
138 if (TREE_CODE (ptr) != SSA_NAME)
139 return true;
140
141 pi = SSA_NAME_PTR_INFO (ptr);
142
143 /* If we do not have points-to information for this variable,
144 we have to punt. */
145 if (!pi)
146 return true;
147
148 /* ??? This does not use TBAA to prune globals ptr may not access. */
149 return pt_solution_includes_global (&pi->pt);
150}
151
152/* Return true if dereferencing PTR may alias DECL.
153 The caller is responsible for applying TBAA to see if PTR
154 may access DECL at all. */
155
156static bool
157ptr_deref_may_alias_decl_p (tree ptr, tree decl)
158{
159 struct ptr_info_def *pi;
160
161 /* Conversions are irrelevant for points-to information and
162 data-dependence analysis can feed us those. */
163 STRIP_NOPS (ptr);
164
165 /* Anything we do not explicilty handle aliases. */
166 if ((TREE_CODE (ptr) != SSA_NAME
167 && TREE_CODE (ptr) != ADDR_EXPR
168 && TREE_CODE (ptr) != POINTER_PLUS_EXPR)
169 || !POINTER_TYPE_P (TREE_TYPE (ptr))
170 || (!VAR_P (decl)
171 && TREE_CODE (decl) != PARM_DECL
172 && TREE_CODE (decl) != RESULT_DECL))
173 return true;
174
175 /* Disregard pointer offsetting. */
176 if (TREE_CODE (ptr) == POINTER_PLUS_EXPR)
177 {
178 do
179 {
180 ptr = TREE_OPERAND (ptr, 0);
181 }
182 while (TREE_CODE (ptr) == POINTER_PLUS_EXPR);
183 return ptr_deref_may_alias_decl_p (ptr, decl);
184 }
185
186 /* ADDR_EXPR pointers either just offset another pointer or directly
187 specify the pointed-to set. */
188 if (TREE_CODE (ptr) == ADDR_EXPR)
189 {
190 tree base = get_base_address (TREE_OPERAND (ptr, 0));
191 if (base
192 && (TREE_CODE (base) == MEM_REF
193 || TREE_CODE (base) == TARGET_MEM_REF))
194 ptr = TREE_OPERAND (base, 0);
195 else if (base
196 && DECL_P (base))
197 return compare_base_decls (base, decl) != 0;
198 else if (base
199 && CONSTANT_CLASS_P (base))
200 return false;
201 else
202 return true;
203 }
204
205 /* Non-aliased variables can not be pointed to. */
206 if (!may_be_aliased (decl))
207 return false;
208
209 /* If we do not have useful points-to information for this pointer
210 we cannot disambiguate anything else. */
211 pi = SSA_NAME_PTR_INFO (ptr);
212 if (!pi)
213 return true;
214
215 return pt_solution_includes (&pi->pt, decl);
216}
217
218/* Return true if dereferenced PTR1 and PTR2 may alias.
219 The caller is responsible for applying TBAA to see if accesses
220 through PTR1 and PTR2 may conflict at all. */
221
222bool
223ptr_derefs_may_alias_p (tree ptr1, tree ptr2)
224{
225 struct ptr_info_def *pi1, *pi2;
226
227 /* Conversions are irrelevant for points-to information and
228 data-dependence analysis can feed us those. */
229 STRIP_NOPS (ptr1);
230 STRIP_NOPS (ptr2);
231
232 /* Disregard pointer offsetting. */
233 if (TREE_CODE (ptr1) == POINTER_PLUS_EXPR)
234 {
235 do
236 {
237 ptr1 = TREE_OPERAND (ptr1, 0);
238 }
239 while (TREE_CODE (ptr1) == POINTER_PLUS_EXPR);
240 return ptr_derefs_may_alias_p (ptr1, ptr2);
241 }
242 if (TREE_CODE (ptr2) == POINTER_PLUS_EXPR)
243 {
244 do
245 {
246 ptr2 = TREE_OPERAND (ptr2, 0);
247 }
248 while (TREE_CODE (ptr2) == POINTER_PLUS_EXPR);
249 return ptr_derefs_may_alias_p (ptr1, ptr2);
250 }
251
252 /* ADDR_EXPR pointers either just offset another pointer or directly
253 specify the pointed-to set. */
254 if (TREE_CODE (ptr1) == ADDR_EXPR)
255 {
256 tree base = get_base_address (TREE_OPERAND (ptr1, 0));
257 if (base
258 && (TREE_CODE (base) == MEM_REF
259 || TREE_CODE (base) == TARGET_MEM_REF))
260 return ptr_derefs_may_alias_p (TREE_OPERAND (base, 0), ptr2);
261 else if (base
262 && DECL_P (base))
263 return ptr_deref_may_alias_decl_p (ptr2, base);
264 else
265 return true;
266 }
267 if (TREE_CODE (ptr2) == ADDR_EXPR)
268 {
269 tree base = get_base_address (TREE_OPERAND (ptr2, 0));
270 if (base
271 && (TREE_CODE (base) == MEM_REF
272 || TREE_CODE (base) == TARGET_MEM_REF))
273 return ptr_derefs_may_alias_p (ptr1, TREE_OPERAND (base, 0));
274 else if (base
275 && DECL_P (base))
276 return ptr_deref_may_alias_decl_p (ptr1, base);
277 else
278 return true;
279 }
280
281 /* From here we require SSA name pointers. Anything else aliases. */
282 if (TREE_CODE (ptr1) != SSA_NAME
283 || TREE_CODE (ptr2) != SSA_NAME
284 || !POINTER_TYPE_P (TREE_TYPE (ptr1))
285 || !POINTER_TYPE_P (TREE_TYPE (ptr2)))
286 return true;
287
288 /* We may end up with two empty points-to solutions for two same pointers.
289 In this case we still want to say both pointers alias, so shortcut
290 that here. */
291 if (ptr1 == ptr2)
292 return true;
293
294 /* If we do not have useful points-to information for either pointer
295 we cannot disambiguate anything else. */
296 pi1 = SSA_NAME_PTR_INFO (ptr1);
297 pi2 = SSA_NAME_PTR_INFO (ptr2);
298 if (!pi1 || !pi2)
299 return true;
300
301 /* ??? This does not use TBAA to prune decls from the intersection
302 that not both pointers may access. */
303 return pt_solutions_intersect (&pi1->pt, &pi2->pt);
304}
305
306/* Return true if dereferencing PTR may alias *REF.
307 The caller is responsible for applying TBAA to see if PTR
308 may access *REF at all. */
309
310static bool
311ptr_deref_may_alias_ref_p_1 (tree ptr, ao_ref *ref)
312{
313 tree base = ao_ref_base (ref);
314
315 if (TREE_CODE (base) == MEM_REF
316 || TREE_CODE (base) == TARGET_MEM_REF)
317 return ptr_derefs_may_alias_p (ptr, TREE_OPERAND (base, 0));
318 else if (DECL_P (base))
319 return ptr_deref_may_alias_decl_p (ptr, base);
320
321 return true;
322}
323
324/* Returns true if PTR1 and PTR2 compare unequal because of points-to. */
325
326bool
327ptrs_compare_unequal (tree ptr1, tree ptr2)
328{
329 /* First resolve the pointers down to a SSA name pointer base or
330 a VAR_DECL, PARM_DECL or RESULT_DECL. This explicitely does
331 not yet try to handle LABEL_DECLs, FUNCTION_DECLs, CONST_DECLs
332 or STRING_CSTs which needs points-to adjustments to track them
333 in the points-to sets. */
334 tree obj1 = NULL_TREE;
335 tree obj2 = NULL_TREE;
336 if (TREE_CODE (ptr1) == ADDR_EXPR)
337 {
338 tree tem = get_base_address (TREE_OPERAND (ptr1, 0));
339 if (! tem)
340 return false;
341 if (VAR_P (tem)
342 || TREE_CODE (tem) == PARM_DECL
343 || TREE_CODE (tem) == RESULT_DECL)
344 obj1 = tem;
345 else if (TREE_CODE (tem) == MEM_REF)
346 ptr1 = TREE_OPERAND (tem, 0);
347 }
348 if (TREE_CODE (ptr2) == ADDR_EXPR)
349 {
350 tree tem = get_base_address (TREE_OPERAND (ptr2, 0));
351 if (! tem)
352 return false;
353 if (VAR_P (tem)
354 || TREE_CODE (tem) == PARM_DECL
355 || TREE_CODE (tem) == RESULT_DECL)
356 obj2 = tem;
357 else if (TREE_CODE (tem) == MEM_REF)
358 ptr2 = TREE_OPERAND (tem, 0);
359 }
360
361 /* Canonicalize ptr vs. object. */
362 if (TREE_CODE (ptr1) == SSA_NAME && obj2)
363 {
364 std::swap (ptr1, ptr2);
365 std::swap (obj1, obj2);
366 }
367
368 if (obj1 && obj2)
369 /* Other code handles this correctly, no need to duplicate it here. */;
370 else if (obj1 && TREE_CODE (ptr2) == SSA_NAME)
371 {
372 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr2);
373 /* We may not use restrict to optimize pointer comparisons.
374 See PR71062. So we have to assume that restrict-pointed-to
375 may be in fact obj1. */
376 if (!pi
377 || pi->pt.vars_contains_restrict
378 || pi->pt.vars_contains_interposable)
379 return false;
380 if (VAR_P (obj1)
381 && (TREE_STATIC (obj1) || DECL_EXTERNAL (obj1)))
382 {
383 varpool_node *node = varpool_node::get (obj1);
384 /* If obj1 may bind to NULL give up (see below). */
385 if (! node
386 || ! node->nonzero_address ()
387 || ! decl_binds_to_current_def_p (obj1))
388 return false;
389 }
390 return !pt_solution_includes (&pi->pt, obj1);
391 }
392
393 /* ??? We'd like to handle ptr1 != NULL and ptr1 != ptr2
394 but those require pt.null to be conservatively correct. */
395
396 return false;
397}
398
399/* Returns whether reference REF to BASE may refer to global memory. */
400
401static bool
402ref_may_alias_global_p_1 (tree base)
403{
404 if (DECL_P (base))
405 return is_global_var (base);
406 else if (TREE_CODE (base) == MEM_REF
407 || TREE_CODE (base) == TARGET_MEM_REF)
408 return ptr_deref_may_alias_global_p (TREE_OPERAND (base, 0));
409 return true;
410}
411
412bool
413ref_may_alias_global_p (ao_ref *ref)
414{
415 tree base = ao_ref_base (ref);
416 return ref_may_alias_global_p_1 (base);
417}
418
419bool
420ref_may_alias_global_p (tree ref)
421{
422 tree base = get_base_address (ref);
423 return ref_may_alias_global_p_1 (base);
424}
425
426/* Return true whether STMT may clobber global memory. */
427
428bool
429stmt_may_clobber_global_p (gimple *stmt)
430{
431 tree lhs;
432
433 if (!gimple_vdef (stmt))
434 return false;
435
436 /* ??? We can ask the oracle whether an artificial pointer
437 dereference with a pointer with points-to information covering
438 all global memory (what about non-address taken memory?) maybe
439 clobbered by this call. As there is at the moment no convenient
440 way of doing that without generating garbage do some manual
441 checking instead.
442 ??? We could make a NULL ao_ref argument to the various
443 predicates special, meaning any global memory. */
444
445 switch (gimple_code (stmt))
446 {
447 case GIMPLE_ASSIGN:
448 lhs = gimple_assign_lhs (stmt);
449 return (TREE_CODE (lhs) != SSA_NAME
450 && ref_may_alias_global_p (lhs));
451 case GIMPLE_CALL:
452 return true;
453 default:
454 return true;
455 }
456}
457
458
459/* Dump alias information on FILE. */
460
461void
462dump_alias_info (FILE *file)
463{
464 unsigned i;
465 tree ptr;
466 const char *funcname
467 = lang_hooks.decl_printable_name (current_function_decl, 2);
468 tree var;
469
470 fprintf (file, "\n\nAlias information for %s\n\n", funcname);
471
472 fprintf (file, "Aliased symbols\n\n");
473
474 FOR_EACH_LOCAL_DECL (cfun, i, var)
475 {
476 if (may_be_aliased (var))
477 dump_variable (file, var);
478 }
479
480 fprintf (file, "\nCall clobber information\n");
481
482 fprintf (file, "\nESCAPED");
483 dump_points_to_solution (file, &cfun->gimple_df->escaped);
484
485 fprintf (file, "\n\nFlow-insensitive points-to information\n\n");
486
487 FOR_EACH_SSA_NAME (i, ptr, cfun)
488 {
489 struct ptr_info_def *pi;
490
491 if (!POINTER_TYPE_P (TREE_TYPE (ptr))
492 || SSA_NAME_IN_FREE_LIST (ptr))
493 continue;
494
495 pi = SSA_NAME_PTR_INFO (ptr);
496 if (pi)
497 dump_points_to_info_for (file, ptr);
498 }
499
500 fprintf (file, "\n");
501}
502
503
504/* Dump alias information on stderr. */
505
506DEBUG_FUNCTION void
507debug_alias_info (void)
508{
509 dump_alias_info (stderr);
510}
511
512
513/* Dump the points-to set *PT into FILE. */
514
515void
516dump_points_to_solution (FILE *file, struct pt_solution *pt)
517{
518 if (pt->anything)
519 fprintf (file, ", points-to anything");
520
521 if (pt->nonlocal)
522 fprintf (file, ", points-to non-local");
523
524 if (pt->escaped)
525 fprintf (file, ", points-to escaped");
526
527 if (pt->ipa_escaped)
528 fprintf (file, ", points-to unit escaped");
529
530 if (pt->null)
531 fprintf (file, ", points-to NULL");
532
533 if (pt->vars)
534 {
535 fprintf (file, ", points-to vars: ");
536 dump_decl_set (file, pt->vars);
537 if (pt->vars_contains_nonlocal
538 || pt->vars_contains_escaped
539 || pt->vars_contains_escaped_heap
540 || pt->vars_contains_restrict)
541 {
542 const char *comma = "";
543 fprintf (file, " (");
544 if (pt->vars_contains_nonlocal)
545 {
546 fprintf (file, "nonlocal");
547 comma = ", ";
548 }
549 if (pt->vars_contains_escaped)
550 {
551 fprintf (file, "%sescaped", comma);
552 comma = ", ";
553 }
554 if (pt->vars_contains_escaped_heap)
555 {
556 fprintf (file, "%sescaped heap", comma);
557 comma = ", ";
558 }
559 if (pt->vars_contains_restrict)
560 {
561 fprintf (file, "%srestrict", comma);
562 comma = ", ";
563 }
564 if (pt->vars_contains_interposable)
565 fprintf (file, "%sinterposable", comma);
566 fprintf (file, ")");
567 }
568 }
569}
570
571
572/* Unified dump function for pt_solution. */
573
574DEBUG_FUNCTION void
575debug (pt_solution &ref)
576{
577 dump_points_to_solution (stderr, &ref);
578}
579
580DEBUG_FUNCTION void
581debug (pt_solution *ptr)
582{
583 if (ptr)
584 debug (*ptr);
585 else
586 fprintf (stderr, "<nil>\n");
587}
588
589
590/* Dump points-to information for SSA_NAME PTR into FILE. */
591
592void
593dump_points_to_info_for (FILE *file, tree ptr)
594{
595 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
596
597 print_generic_expr (file, ptr, dump_flags);
598
599 if (pi)
600 dump_points_to_solution (file, &pi->pt);
601 else
602 fprintf (file, ", points-to anything");
603
604 fprintf (file, "\n");
605}
606
607
608/* Dump points-to information for VAR into stderr. */
609
610DEBUG_FUNCTION void
611debug_points_to_info_for (tree var)
612{
613 dump_points_to_info_for (stderr, var);
614}
615
616
617/* Initializes the alias-oracle reference representation *R from REF. */
618
619void
620ao_ref_init (ao_ref *r, tree ref)
621{
622 r->ref = ref;
623 r->base = NULL_TREE;
624 r->offset = 0;
625 r->size = -1;
626 r->max_size = -1;
627 r->ref_alias_set = -1;
628 r->base_alias_set = -1;
629 r->volatile_p = ref ? TREE_THIS_VOLATILE (ref) : false;
630}
631
632/* Returns the base object of the memory reference *REF. */
633
634tree
635ao_ref_base (ao_ref *ref)
636{
637 bool reverse;
638
639 if (ref->base)
640 return ref->base;
641 ref->base = get_ref_base_and_extent (ref->ref, &ref->offset, &ref->size,
642 &ref->max_size, &reverse);
643 return ref->base;
644}
645
646/* Returns the base object alias set of the memory reference *REF. */
647
648alias_set_type
649ao_ref_base_alias_set (ao_ref *ref)
650{
651 tree base_ref;
652 if (ref->base_alias_set != -1)
653 return ref->base_alias_set;
654 if (!ref->ref)
655 return 0;
656 base_ref = ref->ref;
657 while (handled_component_p (base_ref))
658 base_ref = TREE_OPERAND (base_ref, 0);
659 ref->base_alias_set = get_alias_set (base_ref);
660 return ref->base_alias_set;
661}
662
663/* Returns the reference alias set of the memory reference *REF. */
664
665alias_set_type
666ao_ref_alias_set (ao_ref *ref)
667{
668 if (ref->ref_alias_set != -1)
669 return ref->ref_alias_set;
670 ref->ref_alias_set = get_alias_set (ref->ref);
671 return ref->ref_alias_set;
672}
673
674/* Init an alias-oracle reference representation from a gimple pointer
675 PTR and a gimple size SIZE in bytes. If SIZE is NULL_TREE then the
676 size is assumed to be unknown. The access is assumed to be only
677 to or after of the pointer target, not before it. */
678
679void
680ao_ref_init_from_ptr_and_size (ao_ref *ref, tree ptr, tree size)
681{
682 HOST_WIDE_INT t, size_hwi, extra_offset = 0;
683 ref->ref = NULL_TREE;
684 if (TREE_CODE (ptr) == SSA_NAME)
685 {
686 gimple *stmt = SSA_NAME_DEF_STMT (ptr);
687 if (gimple_assign_single_p (stmt)
688 && gimple_assign_rhs_code (stmt) == ADDR_EXPR)
689 ptr = gimple_assign_rhs1 (stmt);
690 else if (is_gimple_assign (stmt)
691 && gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR
692 && TREE_CODE (gimple_assign_rhs2 (stmt)) == INTEGER_CST)
693 {
694 ptr = gimple_assign_rhs1 (stmt);
695 extra_offset = BITS_PER_UNIT
696 * int_cst_value (gimple_assign_rhs2 (stmt));
697 }
698 }
699
700 if (TREE_CODE (ptr) == ADDR_EXPR)
701 {
702 ref->base = get_addr_base_and_unit_offset (TREE_OPERAND (ptr, 0), &t);
703 if (ref->base)
704 ref->offset = BITS_PER_UNIT * t;
705 else
706 {
707 size = NULL_TREE;
708 ref->offset = 0;
709 ref->base = get_base_address (TREE_OPERAND (ptr, 0));
710 }
711 }
712 else
713 {
714 ref->base = build2 (MEM_REF, char_type_node,
715 ptr, null_pointer_node);
716 ref->offset = 0;
717 }
718 ref->offset += extra_offset;
719 if (size
720 && tree_fits_shwi_p (size)
721 && (size_hwi = tree_to_shwi (size)) <= HOST_WIDE_INT_MAX / BITS_PER_UNIT)
722 ref->max_size = ref->size = size_hwi * BITS_PER_UNIT;
723 else
724 ref->max_size = ref->size = -1;
725 ref->ref_alias_set = 0;
726 ref->base_alias_set = 0;
727 ref->volatile_p = false;
728}
729
730/* Return 1 if TYPE1 and TYPE2 are to be considered equivalent for the
731 purpose of TBAA. Return 0 if they are distinct and -1 if we cannot
732 decide. */
733
734static inline int
735same_type_for_tbaa (tree type1, tree type2)
736{
737 type1 = TYPE_MAIN_VARIANT (type1);
738 type2 = TYPE_MAIN_VARIANT (type2);
739
740 /* If we would have to do structural comparison bail out. */
741 if (TYPE_STRUCTURAL_EQUALITY_P (type1)
742 || TYPE_STRUCTURAL_EQUALITY_P (type2))
743 return -1;
744
745 /* Compare the canonical types. */
746 if (TYPE_CANONICAL (type1) == TYPE_CANONICAL (type2))
747 return 1;
748
749 /* ??? Array types are not properly unified in all cases as we have
750 spurious changes in the index types for example. Removing this
751 causes all sorts of problems with the Fortran frontend. */
752 if (TREE_CODE (type1) == ARRAY_TYPE
753 && TREE_CODE (type2) == ARRAY_TYPE)
754 return -1;
755
756 /* ??? In Ada, an lvalue of an unconstrained type can be used to access an
757 object of one of its constrained subtypes, e.g. when a function with an
758 unconstrained parameter passed by reference is called on an object and
759 inlined. But, even in the case of a fixed size, type and subtypes are
760 not equivalent enough as to share the same TYPE_CANONICAL, since this
761 would mean that conversions between them are useless, whereas they are
762 not (e.g. type and subtypes can have different modes). So, in the end,
763 they are only guaranteed to have the same alias set. */
764 if (get_alias_set (type1) == get_alias_set (type2))
765 return -1;
766
767 /* The types are known to be not equal. */
768 return 0;
769}
770
771/* Determine if the two component references REF1 and REF2 which are
772 based on access types TYPE1 and TYPE2 and of which at least one is based
773 on an indirect reference may alias. REF2 is the only one that can
774 be a decl in which case REF2_IS_DECL is true.
775 REF1_ALIAS_SET, BASE1_ALIAS_SET, REF2_ALIAS_SET and BASE2_ALIAS_SET
776 are the respective alias sets. */
777
778static bool
779aliasing_component_refs_p (tree ref1,
780 alias_set_type ref1_alias_set,
781 alias_set_type base1_alias_set,
782 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
783 tree ref2,
784 alias_set_type ref2_alias_set,
785 alias_set_type base2_alias_set,
786 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
787 bool ref2_is_decl)
788{
789 /* If one reference is a component references through pointers try to find a
790 common base and apply offset based disambiguation. This handles
791 for example
792 struct A { int i; int j; } *q;
793 struct B { struct A a; int k; } *p;
794 disambiguating q->i and p->a.j. */
795 tree base1, base2;
796 tree type1, type2;
797 tree *refp;
798 int same_p;
799
800 /* Choose bases and base types to search for. */
801 base1 = ref1;
802 while (handled_component_p (base1))
803 base1 = TREE_OPERAND (base1, 0);
804 type1 = TREE_TYPE (base1);
805 base2 = ref2;
806 while (handled_component_p (base2))
807 base2 = TREE_OPERAND (base2, 0);
808 type2 = TREE_TYPE (base2);
809
810 /* Now search for the type1 in the access path of ref2. This
811 would be a common base for doing offset based disambiguation on. */
812 refp = &ref2;
813 while (handled_component_p (*refp)
814 && same_type_for_tbaa (TREE_TYPE (*refp), type1) == 0)
815 refp = &TREE_OPERAND (*refp, 0);
816 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type1);
817 /* If we couldn't compare types we have to bail out. */
818 if (same_p == -1)
819 return true;
820 else if (same_p == 1)
821 {
822 HOST_WIDE_INT offadj, sztmp, msztmp;
823 bool reverse;
824 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp, &reverse);
825 offset2 -= offadj;
826 get_ref_base_and_extent (base1, &offadj, &sztmp, &msztmp, &reverse);
827 offset1 -= offadj;
828 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
829 }
830 /* If we didn't find a common base, try the other way around. */
831 refp = &ref1;
832 while (handled_component_p (*refp)
833 && same_type_for_tbaa (TREE_TYPE (*refp), type2) == 0)
834 refp = &TREE_OPERAND (*refp, 0);
835 same_p = same_type_for_tbaa (TREE_TYPE (*refp), type2);
836 /* If we couldn't compare types we have to bail out. */
837 if (same_p == -1)
838 return true;
839 else if (same_p == 1)
840 {
841 HOST_WIDE_INT offadj, sztmp, msztmp;
842 bool reverse;
843 get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp, &reverse);
844 offset1 -= offadj;
845 get_ref_base_and_extent (base2, &offadj, &sztmp, &msztmp, &reverse);
846 offset2 -= offadj;
847 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
848 }
849
850 /* If we have two type access paths B1.path1 and B2.path2 they may
851 only alias if either B1 is in B2.path2 or B2 is in B1.path1.
852 But we can still have a path that goes B1.path1...B2.path2 with
853 a part that we do not see. So we can only disambiguate now
854 if there is no B2 in the tail of path1 and no B1 on the
855 tail of path2. */
856 if (base1_alias_set == ref2_alias_set
857 || alias_set_subset_of (base1_alias_set, ref2_alias_set))
858 return true;
859 /* If this is ptr vs. decl then we know there is no ptr ... decl path. */
860 if (!ref2_is_decl)
861 return (base2_alias_set == ref1_alias_set
862 || alias_set_subset_of (base2_alias_set, ref1_alias_set));
863 return false;
864}
865
866/* Return true if we can determine that component references REF1 and REF2,
867 that are within a common DECL, cannot overlap. */
868
869static bool
870nonoverlapping_component_refs_of_decl_p (tree ref1, tree ref2)
871{
872 auto_vec<tree, 16> component_refs1;
873 auto_vec<tree, 16> component_refs2;
874
875 /* Create the stack of handled components for REF1. */
876 while (handled_component_p (ref1))
877 {
878 component_refs1.safe_push (ref1);
879 ref1 = TREE_OPERAND (ref1, 0);
880 }
881 if (TREE_CODE (ref1) == MEM_REF)
882 {
883 if (!integer_zerop (TREE_OPERAND (ref1, 1)))
884 return false;
885 ref1 = TREE_OPERAND (TREE_OPERAND (ref1, 0), 0);
886 }
887
888 /* Create the stack of handled components for REF2. */
889 while (handled_component_p (ref2))
890 {
891 component_refs2.safe_push (ref2);
892 ref2 = TREE_OPERAND (ref2, 0);
893 }
894 if (TREE_CODE (ref2) == MEM_REF)
895 {
896 if (!integer_zerop (TREE_OPERAND (ref2, 1)))
897 return false;
898 ref2 = TREE_OPERAND (TREE_OPERAND (ref2, 0), 0);
899 }
900
901 /* Bases must be either same or uncomparable. */
902 gcc_checking_assert (ref1 == ref2
903 || (DECL_P (ref1) && DECL_P (ref2)
904 && compare_base_decls (ref1, ref2) != 0));
905
906 /* Pop the stacks in parallel and examine the COMPONENT_REFs of the same
907 rank. This is sufficient because we start from the same DECL and you
908 cannot reference several fields at a time with COMPONENT_REFs (unlike
909 with ARRAY_RANGE_REFs for arrays) so you always need the same number
910 of them to access a sub-component, unless you're in a union, in which
911 case the return value will precisely be false. */
912 while (true)
913 {
914 do
915 {
916 if (component_refs1.is_empty ())
917 return false;
918 ref1 = component_refs1.pop ();
919 }
920 while (!RECORD_OR_UNION_TYPE_P (TREE_TYPE (TREE_OPERAND (ref1, 0))));
921
922 do
923 {
924 if (component_refs2.is_empty ())
925 return false;
926 ref2 = component_refs2.pop ();
927 }
928 while (!RECORD_OR_UNION_TYPE_P (TREE_TYPE (TREE_OPERAND (ref2, 0))));
929
930 /* Beware of BIT_FIELD_REF. */
931 if (TREE_CODE (ref1) != COMPONENT_REF
932 || TREE_CODE (ref2) != COMPONENT_REF)
933 return false;
934
935 tree field1 = TREE_OPERAND (ref1, 1);
936 tree field2 = TREE_OPERAND (ref2, 1);
937
938 /* ??? We cannot simply use the type of operand #0 of the refs here
939 as the Fortran compiler smuggles type punning into COMPONENT_REFs
940 for common blocks instead of using unions like everyone else. */
941 tree type1 = DECL_CONTEXT (field1);
942 tree type2 = DECL_CONTEXT (field2);
943
944 /* We cannot disambiguate fields in a union or qualified union. */
945 if (type1 != type2 || TREE_CODE (type1) != RECORD_TYPE)
946 return false;
947
948 if (field1 != field2)
949 {
950 /* A field and its representative need to be considered the
951 same. */
952 if (DECL_BIT_FIELD_REPRESENTATIVE (field1) == field2
953 || DECL_BIT_FIELD_REPRESENTATIVE (field2) == field1)
954 return false;
955 /* Different fields of the same record type cannot overlap.
956 ??? Bitfields can overlap at RTL level so punt on them. */
957 if (DECL_BIT_FIELD (field1) && DECL_BIT_FIELD (field2))
958 return false;
959 return true;
960 }
961 }
962
963 return false;
964}
965
966/* qsort compare function to sort FIELD_DECLs after their
967 DECL_FIELD_CONTEXT TYPE_UID. */
968
969static inline int
970ncr_compar (const void *field1_, const void *field2_)
971{
972 const_tree field1 = *(const_tree *) const_cast <void *>(field1_);
973 const_tree field2 = *(const_tree *) const_cast <void *>(field2_);
974 unsigned int uid1 = TYPE_UID (DECL_FIELD_CONTEXT (field1));
975 unsigned int uid2 = TYPE_UID (DECL_FIELD_CONTEXT (field2));
976 if (uid1 < uid2)
977 return -1;
978 else if (uid1 > uid2)
979 return 1;
980 return 0;
981}
982
983/* Return true if we can determine that the fields referenced cannot
984 overlap for any pair of objects. */
985
986static bool
987nonoverlapping_component_refs_p (const_tree x, const_tree y)
988{
989 if (!flag_strict_aliasing
990 || !x || !y
991 || TREE_CODE (x) != COMPONENT_REF
992 || TREE_CODE (y) != COMPONENT_REF)
993 return false;
994
995 auto_vec<const_tree, 16> fieldsx;
996 while (TREE_CODE (x) == COMPONENT_REF)
997 {
998 tree field = TREE_OPERAND (x, 1);
999 tree type = DECL_FIELD_CONTEXT (field);
1000 if (TREE_CODE (type) == RECORD_TYPE)
1001 fieldsx.safe_push (field);
1002 x = TREE_OPERAND (x, 0);
1003 }
1004 if (fieldsx.length () == 0)
1005 return false;
1006 auto_vec<const_tree, 16> fieldsy;
1007 while (TREE_CODE (y) == COMPONENT_REF)
1008 {
1009 tree field = TREE_OPERAND (y, 1);
1010 tree type = DECL_FIELD_CONTEXT (field);
1011 if (TREE_CODE (type) == RECORD_TYPE)
1012 fieldsy.safe_push (TREE_OPERAND (y, 1));
1013 y = TREE_OPERAND (y, 0);
1014 }
1015 if (fieldsy.length () == 0)
1016 return false;
1017
1018 /* Most common case first. */
1019 if (fieldsx.length () == 1
1020 && fieldsy.length () == 1)
1021 return ((DECL_FIELD_CONTEXT (fieldsx[0])
1022 == DECL_FIELD_CONTEXT (fieldsy[0]))
1023 && fieldsx[0] != fieldsy[0]
1024 && !(DECL_BIT_FIELD (fieldsx[0]) && DECL_BIT_FIELD (fieldsy[0])));
1025
1026 if (fieldsx.length () == 2)
1027 {
1028 if (ncr_compar (&fieldsx[0], &fieldsx[1]) == 1)
1029 std::swap (fieldsx[0], fieldsx[1]);
1030 }
1031 else
1032 fieldsx.qsort (ncr_compar);
1033
1034 if (fieldsy.length () == 2)
1035 {
1036 if (ncr_compar (&fieldsy[0], &fieldsy[1]) == 1)
1037 std::swap (fieldsy[0], fieldsy[1]);
1038 }
1039 else
1040 fieldsy.qsort (ncr_compar);
1041
1042 unsigned i = 0, j = 0;
1043 do
1044 {
1045 const_tree fieldx = fieldsx[i];
1046 const_tree fieldy = fieldsy[j];
1047 tree typex = DECL_FIELD_CONTEXT (fieldx);
1048 tree typey = DECL_FIELD_CONTEXT (fieldy);
1049 if (typex == typey)
1050 {
1051 /* We're left with accessing different fields of a structure,
1052 no possible overlap. */
1053 if (fieldx != fieldy)
1054 {
1055 /* A field and its representative need to be considered the
1056 same. */
1057 if (DECL_BIT_FIELD_REPRESENTATIVE (fieldx) == fieldy
1058 || DECL_BIT_FIELD_REPRESENTATIVE (fieldy) == fieldx)
1059 return false;
1060 /* Different fields of the same record type cannot overlap.
1061 ??? Bitfields can overlap at RTL level so punt on them. */
1062 if (DECL_BIT_FIELD (fieldx) && DECL_BIT_FIELD (fieldy))
1063 return false;
1064 return true;
1065 }
1066 }
1067 if (TYPE_UID (typex) < TYPE_UID (typey))
1068 {
1069 i++;
1070 if (i == fieldsx.length ())
1071 break;
1072 }
1073 else
1074 {
1075 j++;
1076 if (j == fieldsy.length ())
1077 break;
1078 }
1079 }
1080 while (1);
1081
1082 return false;
1083}
1084
1085
1086/* Return true if two memory references based on the variables BASE1
1087 and BASE2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
1088 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. REF1 and REF2
1089 if non-NULL are the complete memory reference trees. */
1090
1091static bool
1092decl_refs_may_alias_p (tree ref1, tree base1,
1093 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
1094 tree ref2, tree base2,
1095 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
1096{
1097 gcc_checking_assert (DECL_P (base1) && DECL_P (base2));
1098
1099 /* If both references are based on different variables, they cannot alias. */
1100 if (compare_base_decls (base1, base2) == 0)
1101 return false;
1102
1103 /* If both references are based on the same variable, they cannot alias if
1104 the accesses do not overlap. */
1105 if (!ranges_overlap_p (offset1, max_size1, offset2, max_size2))
1106 return false;
1107
1108 /* For components with variable position, the above test isn't sufficient,
1109 so we disambiguate component references manually. */
1110 if (ref1 && ref2
1111 && handled_component_p (ref1) && handled_component_p (ref2)
1112 && nonoverlapping_component_refs_of_decl_p (ref1, ref2))
1113 return false;
1114
1115 return true;
1116}
1117
1118/* Return true if an indirect reference based on *PTR1 constrained
1119 to [OFFSET1, OFFSET1 + MAX_SIZE1) may alias a variable based on BASE2
1120 constrained to [OFFSET2, OFFSET2 + MAX_SIZE2). *PTR1 and BASE2 have
1121 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
1122 in which case they are computed on-demand. REF1 and REF2
1123 if non-NULL are the complete memory reference trees. */
1124
1125static bool
1126indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
1127 HOST_WIDE_INT offset1,
1128 HOST_WIDE_INT max_size1 ATTRIBUTE_UNUSED,
1129 alias_set_type ref1_alias_set,
1130 alias_set_type base1_alias_set,
1131 tree ref2 ATTRIBUTE_UNUSED, tree base2,
1132 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
1133 alias_set_type ref2_alias_set,
1134 alias_set_type base2_alias_set, bool tbaa_p)
1135{
1136 tree ptr1;
1137 tree ptrtype1, dbase2;
1138 HOST_WIDE_INT offset1p = offset1, offset2p = offset2;
1139 HOST_WIDE_INT doffset1, doffset2;
1140
1141 gcc_checking_assert ((TREE_CODE (base1) == MEM_REF
1142 || TREE_CODE (base1) == TARGET_MEM_REF)
1143 && DECL_P (base2));
1144
1145 ptr1 = TREE_OPERAND (base1, 0);
1146
1147 /* The offset embedded in MEM_REFs can be negative. Bias them
1148 so that the resulting offset adjustment is positive. */
1149 offset_int moff = mem_ref_offset (base1);
1150 moff <<= LOG2_BITS_PER_UNIT;
1151 if (wi::neg_p (moff))
1152 offset2p += (-moff).to_short_addr ();
1153 else
1154 offset1p += moff.to_short_addr ();
1155
1156 /* If only one reference is based on a variable, they cannot alias if
1157 the pointer access is beyond the extent of the variable access.
1158 (the pointer base cannot validly point to an offset less than zero
1159 of the variable).
1160 ??? IVOPTs creates bases that do not honor this restriction,
1161 so do not apply this optimization for TARGET_MEM_REFs. */
1162 if (TREE_CODE (base1) != TARGET_MEM_REF
1163 && !ranges_overlap_p (MAX (0, offset1p), -1, offset2p, max_size2))
1164 return false;
1165 /* They also cannot alias if the pointer may not point to the decl. */
1166 if (!ptr_deref_may_alias_decl_p (ptr1, base2))
1167 return false;
1168
1169 /* Disambiguations that rely on strict aliasing rules follow. */
1170 if (!flag_strict_aliasing || !tbaa_p)
1171 return true;
1172
1173 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
1174
1175 /* If the alias set for a pointer access is zero all bets are off. */
1176 if (base1_alias_set == 0)
1177 return true;
1178
1179 /* When we are trying to disambiguate an access with a pointer dereference
1180 as base versus one with a decl as base we can use both the size
1181 of the decl and its dynamic type for extra disambiguation.
1182 ??? We do not know anything about the dynamic type of the decl
1183 other than that its alias-set contains base2_alias_set as a subset
1184 which does not help us here. */
1185 /* As we know nothing useful about the dynamic type of the decl just
1186 use the usual conflict check rather than a subset test.
1187 ??? We could introduce -fvery-strict-aliasing when the language
1188 does not allow decls to have a dynamic type that differs from their
1189 static type. Then we can check
1190 !alias_set_subset_of (base1_alias_set, base2_alias_set) instead. */
1191 if (base1_alias_set != base2_alias_set
1192 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
1193 return false;
1194 /* If the size of the access relevant for TBAA through the pointer
1195 is bigger than the size of the decl we can't possibly access the
1196 decl via that pointer. */
1197 if (DECL_SIZE (base2) && COMPLETE_TYPE_P (TREE_TYPE (ptrtype1))
1198 && TREE_CODE (DECL_SIZE (base2)) == INTEGER_CST
1199 && TREE_CODE (TYPE_SIZE (TREE_TYPE (ptrtype1))) == INTEGER_CST
1200 /* ??? This in turn may run afoul when a decl of type T which is
1201 a member of union type U is accessed through a pointer to
1202 type U and sizeof T is smaller than sizeof U. */
1203 && TREE_CODE (TREE_TYPE (ptrtype1)) != UNION_TYPE
1204 && TREE_CODE (TREE_TYPE (ptrtype1)) != QUAL_UNION_TYPE
1205 && tree_int_cst_lt (DECL_SIZE (base2), TYPE_SIZE (TREE_TYPE (ptrtype1))))
1206 return false;
1207
1208 if (!ref2)
1209 return true;
1210
1211 /* If the decl is accessed via a MEM_REF, reconstruct the base
1212 we can use for TBAA and an appropriately adjusted offset. */
1213 dbase2 = ref2;
1214 while (handled_component_p (dbase2))
1215 dbase2 = TREE_OPERAND (dbase2, 0);
1216 doffset1 = offset1;
1217 doffset2 = offset2;
1218 if (TREE_CODE (dbase2) == MEM_REF
1219 || TREE_CODE (dbase2) == TARGET_MEM_REF)
1220 {
1221 offset_int moff = mem_ref_offset (dbase2);
1222 moff <<= LOG2_BITS_PER_UNIT;
1223 if (wi::neg_p (moff))
1224 doffset1 -= (-moff).to_short_addr ();
1225 else
1226 doffset2 -= moff.to_short_addr ();
1227 }
1228
1229 /* If either reference is view-converted, give up now. */
1230 if (same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) != 1
1231 || same_type_for_tbaa (TREE_TYPE (dbase2), TREE_TYPE (base2)) != 1)
1232 return true;
1233
1234 /* If both references are through the same type, they do not alias
1235 if the accesses do not overlap. This does extra disambiguation
1236 for mixed/pointer accesses but requires strict aliasing.
1237 For MEM_REFs we require that the component-ref offset we computed
1238 is relative to the start of the type which we ensure by
1239 comparing rvalue and access type and disregarding the constant
1240 pointer offset. */
1241 if ((TREE_CODE (base1) != TARGET_MEM_REF
1242 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
1243 && same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (dbase2)) == 1)
1244 return ranges_overlap_p (doffset1, max_size1, doffset2, max_size2);
1245
1246 if (ref1 && ref2
1247 && nonoverlapping_component_refs_p (ref1, ref2))
1248 return false;
1249
1250 /* Do access-path based disambiguation. */
1251 if (ref1 && ref2
1252 && (handled_component_p (ref1) || handled_component_p (ref2)))
1253 return aliasing_component_refs_p (ref1,
1254 ref1_alias_set, base1_alias_set,
1255 offset1, max_size1,
1256 ref2,
1257 ref2_alias_set, base2_alias_set,
1258 offset2, max_size2, true);
1259
1260 return true;
1261}
1262
1263/* Return true if two indirect references based on *PTR1
1264 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
1265 [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have
1266 the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
1267 in which case they are computed on-demand. REF1 and REF2
1268 if non-NULL are the complete memory reference trees. */
1269
1270static bool
1271indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
1272 HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
1273 alias_set_type ref1_alias_set,
1274 alias_set_type base1_alias_set,
1275 tree ref2 ATTRIBUTE_UNUSED, tree base2,
1276 HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
1277 alias_set_type ref2_alias_set,
1278 alias_set_type base2_alias_set, bool tbaa_p)
1279{
1280 tree ptr1;
1281 tree ptr2;
1282 tree ptrtype1, ptrtype2;
1283
1284 gcc_checking_assert ((TREE_CODE (base1) == MEM_REF
1285 || TREE_CODE (base1) == TARGET_MEM_REF)
1286 && (TREE_CODE (base2) == MEM_REF
1287 || TREE_CODE (base2) == TARGET_MEM_REF));
1288
1289 ptr1 = TREE_OPERAND (base1, 0);
1290 ptr2 = TREE_OPERAND (base2, 0);
1291
1292 /* If both bases are based on pointers they cannot alias if they may not
1293 point to the same memory object or if they point to the same object
1294 and the accesses do not overlap. */
1295 if ((!cfun || gimple_in_ssa_p (cfun))
1296 && operand_equal_p (ptr1, ptr2, 0)
1297 && (((TREE_CODE (base1) != TARGET_MEM_REF
1298 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
1299 && (TREE_CODE (base2) != TARGET_MEM_REF
1300 || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2))))
1301 || (TREE_CODE (base1) == TARGET_MEM_REF
1302 && TREE_CODE (base2) == TARGET_MEM_REF
1303 && (TMR_STEP (base1) == TMR_STEP (base2)
1304 || (TMR_STEP (base1) && TMR_STEP (base2)
1305 && operand_equal_p (TMR_STEP (base1),
1306 TMR_STEP (base2), 0)))
1307 && (TMR_INDEX (base1) == TMR_INDEX (base2)
1308 || (TMR_INDEX (base1) && TMR_INDEX (base2)
1309 && operand_equal_p (TMR_INDEX (base1),
1310 TMR_INDEX (base2), 0)))
1311 && (TMR_INDEX2 (base1) == TMR_INDEX2 (base2)
1312 || (TMR_INDEX2 (base1) && TMR_INDEX2 (base2)
1313 && operand_equal_p (TMR_INDEX2 (base1),
1314 TMR_INDEX2 (base2), 0))))))
1315 {
1316 offset_int moff;
1317 /* The offset embedded in MEM_REFs can be negative. Bias them
1318 so that the resulting offset adjustment is positive. */
1319 moff = mem_ref_offset (base1);
1320 moff <<= LOG2_BITS_PER_UNIT;
1321 if (wi::neg_p (moff))
1322 offset2 += (-moff).to_short_addr ();
1323 else
1324 offset1 += moff.to_shwi ();
1325 moff = mem_ref_offset (base2);
1326 moff <<= LOG2_BITS_PER_UNIT;
1327 if (wi::neg_p (moff))
1328 offset1 += (-moff).to_short_addr ();
1329 else
1330 offset2 += moff.to_short_addr ();
1331 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
1332 }
1333 if (!ptr_derefs_may_alias_p (ptr1, ptr2))
1334 return false;
1335
1336 /* Disambiguations that rely on strict aliasing rules follow. */
1337 if (!flag_strict_aliasing || !tbaa_p)
1338 return true;
1339
1340 ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
1341 ptrtype2 = TREE_TYPE (TREE_OPERAND (base2, 1));
1342
1343 /* If the alias set for a pointer access is zero all bets are off. */
1344 if (base1_alias_set == 0
1345 || base2_alias_set == 0)
1346 return true;
1347
1348 /* If both references are through the same type, they do not alias
1349 if the accesses do not overlap. This does extra disambiguation
1350 for mixed/pointer accesses but requires strict aliasing. */
1351 if ((TREE_CODE (base1) != TARGET_MEM_REF
1352 || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
1353 && (TREE_CODE (base2) != TARGET_MEM_REF
1354 || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2)))
1355 && same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1
1356 && same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1
1357 && same_type_for_tbaa (TREE_TYPE (ptrtype1),
1358 TREE_TYPE (ptrtype2)) == 1
1359 /* But avoid treating arrays as "objects", instead assume they
1360 can overlap by an exact multiple of their element size. */
1361 && TREE_CODE (TREE_TYPE (ptrtype1)) != ARRAY_TYPE)
1362 return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
1363
1364 /* Do type-based disambiguation. */
1365 if (base1_alias_set != base2_alias_set
1366 && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
1367 return false;
1368
1369 /* If either reference is view-converted, give up now. */
1370 if (same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) != 1
1371 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) != 1)
1372 return true;
1373
1374 if (ref1 && ref2
1375 && nonoverlapping_component_refs_p (ref1, ref2))
1376 return false;
1377
1378 /* Do access-path based disambiguation. */
1379 if (ref1 && ref2
1380 && (handled_component_p (ref1) || handled_component_p (ref2)))
1381 return aliasing_component_refs_p (ref1,
1382 ref1_alias_set, base1_alias_set,
1383 offset1, max_size1,
1384 ref2,
1385 ref2_alias_set, base2_alias_set,
1386 offset2, max_size2, false);
1387
1388 return true;
1389}
1390
1391/* Return true, if the two memory references REF1 and REF2 may alias. */
1392
1393bool
1394refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
1395{
1396 tree base1, base2;
1397 HOST_WIDE_INT offset1 = 0, offset2 = 0;
1398 HOST_WIDE_INT max_size1 = -1, max_size2 = -1;
1399 bool var1_p, var2_p, ind1_p, ind2_p;
1400
1401 gcc_checking_assert ((!ref1->ref
1402 || TREE_CODE (ref1->ref) == SSA_NAME
1403 || DECL_P (ref1->ref)
1404 || TREE_CODE (ref1->ref) == STRING_CST
1405 || handled_component_p (ref1->ref)
1406 || TREE_CODE (ref1->ref) == MEM_REF
1407 || TREE_CODE (ref1->ref) == TARGET_MEM_REF)
1408 && (!ref2->ref
1409 || TREE_CODE (ref2->ref) == SSA_NAME
1410 || DECL_P (ref2->ref)
1411 || TREE_CODE (ref2->ref) == STRING_CST
1412 || handled_component_p (ref2->ref)
1413 || TREE_CODE (ref2->ref) == MEM_REF
1414 || TREE_CODE (ref2->ref) == TARGET_MEM_REF));
1415
1416 /* Decompose the references into their base objects and the access. */
1417 base1 = ao_ref_base (ref1);
1418 offset1 = ref1->offset;
1419 max_size1 = ref1->max_size;
1420 base2 = ao_ref_base (ref2);
1421 offset2 = ref2->offset;
1422 max_size2 = ref2->max_size;
1423
1424 /* We can end up with registers or constants as bases for example from
1425 *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
1426 which is seen as a struct copy. */
1427 if (TREE_CODE (base1) == SSA_NAME
1428 || TREE_CODE (base1) == CONST_DECL
1429 || TREE_CODE (base1) == CONSTRUCTOR
1430 || TREE_CODE (base1) == ADDR_EXPR
1431 || CONSTANT_CLASS_P (base1)
1432 || TREE_CODE (base2) == SSA_NAME
1433 || TREE_CODE (base2) == CONST_DECL
1434 || TREE_CODE (base2) == CONSTRUCTOR
1435 || TREE_CODE (base2) == ADDR_EXPR
1436 || CONSTANT_CLASS_P (base2))
1437 return false;
1438
1439 /* We can end up referring to code via function and label decls.
1440 As we likely do not properly track code aliases conservatively
1441 bail out. */
1442 if (TREE_CODE (base1) == FUNCTION_DECL
1443 || TREE_CODE (base1) == LABEL_DECL
1444 || TREE_CODE (base2) == FUNCTION_DECL
1445 || TREE_CODE (base2) == LABEL_DECL)
1446 return true;
1447
1448 /* Two volatile accesses always conflict. */
1449 if (ref1->volatile_p
1450 && ref2->volatile_p)
1451 return true;
1452
1453 /* Defer to simple offset based disambiguation if we have
1454 references based on two decls. Do this before defering to
1455 TBAA to handle must-alias cases in conformance with the
1456 GCC extension of allowing type-punning through unions. */
1457 var1_p = DECL_P (base1);
1458 var2_p = DECL_P (base2);
1459 if (var1_p && var2_p)
1460 return decl_refs_may_alias_p (ref1->ref, base1, offset1, max_size1,
1461 ref2->ref, base2, offset2, max_size2);
1462
1463 /* Handle restrict based accesses.
1464 ??? ao_ref_base strips inner MEM_REF [&decl], recover from that
1465 here. */
1466 tree rbase1 = base1;
1467 tree rbase2 = base2;
1468 if (var1_p)
1469 {
1470 rbase1 = ref1->ref;
1471 if (rbase1)
1472 while (handled_component_p (rbase1))
1473 rbase1 = TREE_OPERAND (rbase1, 0);
1474 }
1475 if (var2_p)
1476 {
1477 rbase2 = ref2->ref;
1478 if (rbase2)
1479 while (handled_component_p (rbase2))
1480 rbase2 = TREE_OPERAND (rbase2, 0);
1481 }
1482 if (rbase1 && rbase2
1483 && (TREE_CODE (base1) == MEM_REF || TREE_CODE (base1) == TARGET_MEM_REF)
1484 && (TREE_CODE (base2) == MEM_REF || TREE_CODE (base2) == TARGET_MEM_REF)
1485 /* If the accesses are in the same restrict clique... */
1486 && MR_DEPENDENCE_CLIQUE (base1) == MR_DEPENDENCE_CLIQUE (base2)
1487 /* But based on different pointers they do not alias. */
1488 && MR_DEPENDENCE_BASE (base1) != MR_DEPENDENCE_BASE (base2))
1489 return false;
1490
1491 ind1_p = (TREE_CODE (base1) == MEM_REF
1492 || TREE_CODE (base1) == TARGET_MEM_REF);
1493 ind2_p = (TREE_CODE (base2) == MEM_REF
1494 || TREE_CODE (base2) == TARGET_MEM_REF);
1495
1496 /* Canonicalize the pointer-vs-decl case. */
1497 if (ind1_p && var2_p)
1498 {
1499 std::swap (offset1, offset2);
1500 std::swap (max_size1, max_size2);
1501 std::swap (base1, base2);
1502 std::swap (ref1, ref2);
1503 var1_p = true;
1504 ind1_p = false;
1505 var2_p = false;
1506 ind2_p = true;
1507 }
1508
1509 /* First defer to TBAA if possible. */
1510 if (tbaa_p
1511 && flag_strict_aliasing
1512 && !alias_sets_conflict_p (ao_ref_alias_set (ref1),
1513 ao_ref_alias_set (ref2)))
1514 return false;
1515
1516 /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */
1517 if (var1_p && ind2_p)
1518 return indirect_ref_may_alias_decl_p (ref2->ref, base2,
1519 offset2, max_size2,
1520 ao_ref_alias_set (ref2),
1521 ao_ref_base_alias_set (ref2),
1522 ref1->ref, base1,
1523 offset1, max_size1,
1524 ao_ref_alias_set (ref1),
1525 ao_ref_base_alias_set (ref1),
1526 tbaa_p);
1527 else if (ind1_p && ind2_p)
1528 return indirect_refs_may_alias_p (ref1->ref, base1,
1529 offset1, max_size1,
1530 ao_ref_alias_set (ref1),
1531 ao_ref_base_alias_set (ref1),
1532 ref2->ref, base2,
1533 offset2, max_size2,
1534 ao_ref_alias_set (ref2),
1535 ao_ref_base_alias_set (ref2),
1536 tbaa_p);
1537
1538 gcc_unreachable ();
1539}
1540
1541static bool
1542refs_may_alias_p (tree ref1, ao_ref *ref2)
1543{
1544 ao_ref r1;
1545 ao_ref_init (&r1, ref1);
1546 return refs_may_alias_p_1 (&r1, ref2, true);
1547}
1548
1549bool
1550refs_may_alias_p (tree ref1, tree ref2)
1551{
1552 ao_ref r1, r2;
1553 bool res;
1554 ao_ref_init (&r1, ref1);
1555 ao_ref_init (&r2, ref2);
1556 res = refs_may_alias_p_1 (&r1, &r2, true);
1557 if (res)
1558 ++alias_stats.refs_may_alias_p_may_alias;
1559 else
1560 ++alias_stats.refs_may_alias_p_no_alias;
1561 return res;
1562}
1563
1564/* Returns true if there is a anti-dependence for the STORE that
1565 executes after the LOAD. */
1566
1567bool
1568refs_anti_dependent_p (tree load, tree store)
1569{
1570 ao_ref r1, r2;
1571 ao_ref_init (&r1, load);
1572 ao_ref_init (&r2, store);
1573 return refs_may_alias_p_1 (&r1, &r2, false);
1574}
1575
1576/* Returns true if there is a output dependence for the stores
1577 STORE1 and STORE2. */
1578
1579bool
1580refs_output_dependent_p (tree store1, tree store2)
1581{
1582 ao_ref r1, r2;
1583 ao_ref_init (&r1, store1);
1584 ao_ref_init (&r2, store2);
1585 return refs_may_alias_p_1 (&r1, &r2, false);
1586}
1587
1588/* If the call CALL may use the memory reference REF return true,
1589 otherwise return false. */
1590
1591static bool
1592ref_maybe_used_by_call_p_1 (gcall *call, ao_ref *ref)
1593{
1594 tree base, callee;
1595 unsigned i;
1596 int flags = gimple_call_flags (call);
1597
1598 /* Const functions without a static chain do not implicitly use memory. */
1599 if (!gimple_call_chain (call)
1600 && (flags & (ECF_CONST|ECF_NOVOPS)))
1601 goto process_args;
1602
1603 base = ao_ref_base (ref);
1604 if (!base)
1605 return true;
1606
1607 /* A call that is not without side-effects might involve volatile
1608 accesses and thus conflicts with all other volatile accesses. */
1609 if (ref->volatile_p)
1610 return true;
1611
1612 /* If the reference is based on a decl that is not aliased the call
1613 cannot possibly use it. */
1614 if (DECL_P (base)
1615 && !may_be_aliased (base)
1616 /* But local statics can be used through recursion. */
1617 && !is_global_var (base))
1618 goto process_args;
1619
1620 callee = gimple_call_fndecl (call);
1621
1622 /* Handle those builtin functions explicitly that do not act as
1623 escape points. See tree-ssa-structalias.c:find_func_aliases
1624 for the list of builtins we might need to handle here. */
1625 if (callee != NULL_TREE
1626 && gimple_call_builtin_p (call, BUILT_IN_NORMAL))
1627 switch (DECL_FUNCTION_CODE (callee))
1628 {
1629 /* All the following functions read memory pointed to by
1630 their second argument. strcat/strncat additionally
1631 reads memory pointed to by the first argument. */
1632 case BUILT_IN_STRCAT:
1633 case BUILT_IN_STRNCAT:
1634 {
1635 ao_ref dref;
1636 ao_ref_init_from_ptr_and_size (&dref,
1637 gimple_call_arg (call, 0),
1638 NULL_TREE);
1639 if (refs_may_alias_p_1 (&dref, ref, false))
1640 return true;
1641 }
1642 /* FALLTHRU */
1643 case BUILT_IN_STRCPY:
1644 case BUILT_IN_STRNCPY:
1645 case BUILT_IN_MEMCPY:
1646 case BUILT_IN_MEMMOVE:
1647 case BUILT_IN_MEMPCPY:
1648 case BUILT_IN_STPCPY:
1649 case BUILT_IN_STPNCPY:
1650 case BUILT_IN_TM_MEMCPY:
1651 case BUILT_IN_TM_MEMMOVE:
1652 {
1653 ao_ref dref;
1654 tree size = NULL_TREE;
1655 if (gimple_call_num_args (call) == 3)
1656 size = gimple_call_arg (call, 2);
1657 ao_ref_init_from_ptr_and_size (&dref,
1658 gimple_call_arg (call, 1),
1659 size);
1660 return refs_may_alias_p_1 (&dref, ref, false);
1661 }
1662 case BUILT_IN_STRCAT_CHK:
1663 case BUILT_IN_STRNCAT_CHK:
1664 {
1665 ao_ref dref;
1666 ao_ref_init_from_ptr_and_size (&dref,
1667 gimple_call_arg (call, 0),
1668 NULL_TREE);
1669 if (refs_may_alias_p_1 (&dref, ref, false))
1670 return true;
1671 }
1672 /* FALLTHRU */
1673 case BUILT_IN_STRCPY_CHK:
1674 case BUILT_IN_STRNCPY_CHK:
1675 case BUILT_IN_MEMCPY_CHK:
1676 case BUILT_IN_MEMMOVE_CHK:
1677 case BUILT_IN_MEMPCPY_CHK:
1678 case BUILT_IN_STPCPY_CHK:
1679 case BUILT_IN_STPNCPY_CHK:
1680 {
1681 ao_ref dref;
1682 tree size = NULL_TREE;
1683 if (gimple_call_num_args (call) == 4)
1684 size = gimple_call_arg (call, 2);
1685 ao_ref_init_from_ptr_and_size (&dref,
1686 gimple_call_arg (call, 1),
1687 size);
1688 return refs_may_alias_p_1 (&dref, ref, false);
1689 }
1690 case BUILT_IN_BCOPY:
1691 {
1692 ao_ref dref;
1693 tree size = gimple_call_arg (call, 2);
1694 ao_ref_init_from_ptr_and_size (&dref,
1695 gimple_call_arg (call, 0),
1696 size);
1697 return refs_may_alias_p_1 (&dref, ref, false);
1698 }
1699
1700 /* The following functions read memory pointed to by their
1701 first argument. */
1702 CASE_BUILT_IN_TM_LOAD (1):
1703 CASE_BUILT_IN_TM_LOAD (2):
1704 CASE_BUILT_IN_TM_LOAD (4):
1705 CASE_BUILT_IN_TM_LOAD (8):
1706 CASE_BUILT_IN_TM_LOAD (FLOAT):
1707 CASE_BUILT_IN_TM_LOAD (DOUBLE):
1708 CASE_BUILT_IN_TM_LOAD (LDOUBLE):
1709 CASE_BUILT_IN_TM_LOAD (M64):
1710 CASE_BUILT_IN_TM_LOAD (M128):
1711 CASE_BUILT_IN_TM_LOAD (M256):
1712 case BUILT_IN_TM_LOG:
1713 case BUILT_IN_TM_LOG_1:
1714 case BUILT_IN_TM_LOG_2:
1715 case BUILT_IN_TM_LOG_4:
1716 case BUILT_IN_TM_LOG_8:
1717 case BUILT_IN_TM_LOG_FLOAT:
1718 case BUILT_IN_TM_LOG_DOUBLE:
1719 case BUILT_IN_TM_LOG_LDOUBLE:
1720 case BUILT_IN_TM_LOG_M64:
1721 case BUILT_IN_TM_LOG_M128:
1722 case BUILT_IN_TM_LOG_M256:
1723 return ptr_deref_may_alias_ref_p_1 (gimple_call_arg (call, 0), ref);
1724
1725 /* These read memory pointed to by the first argument. */
1726 case BUILT_IN_STRDUP:
1727 case BUILT_IN_STRNDUP:
1728 case BUILT_IN_REALLOC:
1729 {
1730 ao_ref dref;
1731 tree size = NULL_TREE;
1732 if (gimple_call_num_args (call) == 2)
1733 size = gimple_call_arg (call, 1);
1734 ao_ref_init_from_ptr_and_size (&dref,
1735 gimple_call_arg (call, 0),
1736 size);
1737 return refs_may_alias_p_1 (&dref, ref, false);
1738 }
1739 /* These read memory pointed to by the first argument. */
1740 case BUILT_IN_INDEX:
1741 case BUILT_IN_STRCHR:
1742 case BUILT_IN_STRRCHR:
1743 {
1744 ao_ref dref;
1745 ao_ref_init_from_ptr_and_size (&dref,
1746 gimple_call_arg (call, 0),
1747 NULL_TREE);
1748 return refs_may_alias_p_1 (&dref, ref, false);
1749 }
1750 /* These read memory pointed to by the first argument with size
1751 in the third argument. */
1752 case BUILT_IN_MEMCHR:
1753 {
1754 ao_ref dref;
1755 ao_ref_init_from_ptr_and_size (&dref,
1756 gimple_call_arg (call, 0),
1757 gimple_call_arg (call, 2));
1758 return refs_may_alias_p_1 (&dref, ref, false);
1759 }
1760 /* These read memory pointed to by the first and second arguments. */
1761 case BUILT_IN_STRSTR:
1762 case BUILT_IN_STRPBRK:
1763 {
1764 ao_ref dref;
1765 ao_ref_init_from_ptr_and_size (&dref,
1766 gimple_call_arg (call, 0),
1767 NULL_TREE);
1768 if (refs_may_alias_p_1 (&dref, ref, false))
1769 return true;
1770 ao_ref_init_from_ptr_and_size (&dref,
1771 gimple_call_arg (call, 1),
1772 NULL_TREE);
1773 return refs_may_alias_p_1 (&dref, ref, false);
1774 }
1775
1776 /* The following builtins do not read from memory. */
1777 case BUILT_IN_FREE:
1778 case BUILT_IN_MALLOC:
1779 case BUILT_IN_POSIX_MEMALIGN:
1780 case BUILT_IN_ALIGNED_ALLOC:
1781 case BUILT_IN_CALLOC:
1782 CASE_BUILT_IN_ALLOCA:
1783 case BUILT_IN_STACK_SAVE:
1784 case BUILT_IN_STACK_RESTORE:
1785 case BUILT_IN_MEMSET:
1786 case BUILT_IN_TM_MEMSET:
1787 case BUILT_IN_MEMSET_CHK:
1788 case BUILT_IN_FREXP:
1789 case BUILT_IN_FREXPF:
1790 case BUILT_IN_FREXPL:
1791 case BUILT_IN_GAMMA_R:
1792 case BUILT_IN_GAMMAF_R:
1793 case BUILT_IN_GAMMAL_R:
1794 case BUILT_IN_LGAMMA_R:
1795 case BUILT_IN_LGAMMAF_R:
1796 case BUILT_IN_LGAMMAL_R:
1797 case BUILT_IN_MODF:
1798 case BUILT_IN_MODFF:
1799 case BUILT_IN_MODFL:
1800 case BUILT_IN_REMQUO:
1801 case BUILT_IN_REMQUOF:
1802 case BUILT_IN_REMQUOL:
1803 case BUILT_IN_SINCOS:
1804 case BUILT_IN_SINCOSF:
1805 case BUILT_IN_SINCOSL:
1806 case BUILT_IN_ASSUME_ALIGNED:
1807 case BUILT_IN_VA_END:
1808 return false;
1809 /* __sync_* builtins and some OpenMP builtins act as threading
1810 barriers. */
1811#undef DEF_SYNC_BUILTIN
1812#define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM:
1813#include "sync-builtins.def"
1814#undef DEF_SYNC_BUILTIN
1815 case BUILT_IN_GOMP_ATOMIC_START:
1816 case BUILT_IN_GOMP_ATOMIC_END:
1817 case BUILT_IN_GOMP_BARRIER:
1818 case BUILT_IN_GOMP_BARRIER_CANCEL:
1819 case BUILT_IN_GOMP_TASKWAIT:
1820 case BUILT_IN_GOMP_TASKGROUP_END:
1821 case BUILT_IN_GOMP_CRITICAL_START:
1822 case BUILT_IN_GOMP_CRITICAL_END:
1823 case BUILT_IN_GOMP_CRITICAL_NAME_START:
1824 case BUILT_IN_GOMP_CRITICAL_NAME_END:
1825 case BUILT_IN_GOMP_LOOP_END:
1826 case BUILT_IN_GOMP_LOOP_END_CANCEL:
1827 case BUILT_IN_GOMP_ORDERED_START:
1828 case BUILT_IN_GOMP_ORDERED_END:
1829 case BUILT_IN_GOMP_SECTIONS_END:
1830 case BUILT_IN_GOMP_SECTIONS_END_CANCEL:
1831 case BUILT_IN_GOMP_SINGLE_COPY_START:
1832 case BUILT_IN_GOMP_SINGLE_COPY_END:
1833 return true;
1834
1835 default:
1836 /* Fallthru to general call handling. */;
1837 }
1838
1839 /* Check if base is a global static variable that is not read
1840 by the function. */
1841 if (callee != NULL_TREE && VAR_P (base) && TREE_STATIC (base))
1842 {
1843 struct cgraph_node *node = cgraph_node::get (callee);
1844 bitmap not_read;
1845
1846 /* FIXME: Callee can be an OMP builtin that does not have a call graph
1847 node yet. We should enforce that there are nodes for all decls in the
1848 IL and remove this check instead. */
1849 if (node
1850 && (not_read = ipa_reference_get_not_read_global (node))
1851 && bitmap_bit_p (not_read, ipa_reference_var_uid (base)))
1852 goto process_args;
1853 }
1854
1855 /* Check if the base variable is call-used. */
1856 if (DECL_P (base))
1857 {
1858 if (pt_solution_includes (gimple_call_use_set (call), base))
1859 return true;
1860 }
1861 else if ((TREE_CODE (base) == MEM_REF
1862 || TREE_CODE (base) == TARGET_MEM_REF)
1863 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
1864 {
1865 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
1866 if (!pi)
1867 return true;
1868
1869 if (pt_solutions_intersect (gimple_call_use_set (call), &pi->pt))
1870 return true;
1871 }
1872 else
1873 return true;
1874
1875 /* Inspect call arguments for passed-by-value aliases. */
1876process_args:
1877 for (i = 0; i < gimple_call_num_args (call); ++i)
1878 {
1879 tree op = gimple_call_arg (call, i);
1880 int flags = gimple_call_arg_flags (call, i);
1881
1882 if (flags & EAF_UNUSED)
1883 continue;
1884
1885 if (TREE_CODE (op) == WITH_SIZE_EXPR)
1886 op = TREE_OPERAND (op, 0);
1887
1888 if (TREE_CODE (op) != SSA_NAME
1889 && !is_gimple_min_invariant (op))
1890 {
1891 ao_ref r;
1892 ao_ref_init (&r, op);
1893 if (refs_may_alias_p_1 (&r, ref, true))
1894 return true;
1895 }
1896 }
1897
1898 return false;
1899}
1900
1901static bool
1902ref_maybe_used_by_call_p (gcall *call, ao_ref *ref)
1903{
1904 bool res;
1905 res = ref_maybe_used_by_call_p_1 (call, ref);
1906 if (res)
1907 ++alias_stats.ref_maybe_used_by_call_p_may_alias;
1908 else
1909 ++alias_stats.ref_maybe_used_by_call_p_no_alias;
1910 return res;
1911}
1912
1913
1914/* If the statement STMT may use the memory reference REF return
1915 true, otherwise return false. */
1916
1917bool
1918ref_maybe_used_by_stmt_p (gimple *stmt, ao_ref *ref)
1919{
1920 if (is_gimple_assign (stmt))
1921 {
1922 tree rhs;
1923
1924 /* All memory assign statements are single. */
1925 if (!gimple_assign_single_p (stmt))
1926 return false;
1927
1928 rhs = gimple_assign_rhs1 (stmt);
1929 if (is_gimple_reg (rhs)
1930 || is_gimple_min_invariant (rhs)
1931 || gimple_assign_rhs_code (stmt) == CONSTRUCTOR)
1932 return false;
1933
1934 return refs_may_alias_p (rhs, ref);
1935 }
1936 else if (is_gimple_call (stmt))
1937 return ref_maybe_used_by_call_p (as_a <gcall *> (stmt), ref);
1938 else if (greturn *return_stmt = dyn_cast <greturn *> (stmt))
1939 {
1940 tree retval = gimple_return_retval (return_stmt);
1941 if (retval
1942 && TREE_CODE (retval) != SSA_NAME
1943 && !is_gimple_min_invariant (retval)
1944 && refs_may_alias_p (retval, ref))
1945 return true;
1946 /* If ref escapes the function then the return acts as a use. */
1947 tree base = ao_ref_base (ref);
1948 if (!base)
1949 ;
1950 else if (DECL_P (base))
1951 return is_global_var (base);
1952 else if (TREE_CODE (base) == MEM_REF
1953 || TREE_CODE (base) == TARGET_MEM_REF)
1954 return ptr_deref_may_alias_global_p (TREE_OPERAND (base, 0));
1955 return false;
1956 }
1957
1958 return true;
1959}
1960
1961bool
1962ref_maybe_used_by_stmt_p (gimple *stmt, tree ref)
1963{
1964 ao_ref r;
1965 ao_ref_init (&r, ref);
1966 return ref_maybe_used_by_stmt_p (stmt, &r);
1967}
1968
1969/* If the call in statement CALL may clobber the memory reference REF
1970 return true, otherwise return false. */
1971
1972bool
1973call_may_clobber_ref_p_1 (gcall *call, ao_ref *ref)
1974{
1975 tree base;
1976 tree callee;
1977
1978 /* If the call is pure or const it cannot clobber anything. */
1979 if (gimple_call_flags (call)
1980 & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS))
1981 return false;
1982 if (gimple_call_internal_p (call))
1983 switch (gimple_call_internal_fn (call))
1984 {
1985 /* Treat these internal calls like ECF_PURE for aliasing,
1986 they don't write to any memory the program should care about.
1987 They have important other side-effects, and read memory,
1988 so can't be ECF_NOVOPS. */
1989 case IFN_UBSAN_NULL:
1990 case IFN_UBSAN_BOUNDS:
1991 case IFN_UBSAN_VPTR:
1992 case IFN_UBSAN_OBJECT_SIZE:
1993 case IFN_UBSAN_PTR:
1994 case IFN_ASAN_CHECK:
1995 return false;
1996 default:
1997 break;
1998 }
1999
2000 base = ao_ref_base (ref);
2001 if (!base)
2002 return true;
2003
2004 if (TREE_CODE (base) == SSA_NAME
2005 || CONSTANT_CLASS_P (base))
2006 return false;
2007
2008 /* A call that is not without side-effects might involve volatile
2009 accesses and thus conflicts with all other volatile accesses. */
2010 if (ref->volatile_p)
2011 return true;
2012
2013 /* If the reference is based on a decl that is not aliased the call
2014 cannot possibly clobber it. */
2015 if (DECL_P (base)
2016 && !may_be_aliased (base)
2017 /* But local non-readonly statics can be modified through recursion
2018 or the call may implement a threading barrier which we must
2019 treat as may-def. */
2020 && (TREE_READONLY (base)
2021 || !is_global_var (base)))
2022 return false;
2023
2024 callee = gimple_call_fndecl (call);
2025
2026 /* Handle those builtin functions explicitly that do not act as
2027 escape points. See tree-ssa-structalias.c:find_func_aliases
2028 for the list of builtins we might need to handle here. */
2029 if (callee != NULL_TREE
2030 && gimple_call_builtin_p (call, BUILT_IN_NORMAL))
2031 switch (DECL_FUNCTION_CODE (callee))
2032 {
2033 /* All the following functions clobber memory pointed to by
2034 their first argument. */
2035 case BUILT_IN_STRCPY:
2036 case BUILT_IN_STRNCPY:
2037 case BUILT_IN_MEMCPY:
2038 case BUILT_IN_MEMMOVE:
2039 case BUILT_IN_MEMPCPY:
2040 case BUILT_IN_STPCPY:
2041 case BUILT_IN_STPNCPY:
2042 case BUILT_IN_STRCAT:
2043 case BUILT_IN_STRNCAT:
2044 case BUILT_IN_MEMSET:
2045 case BUILT_IN_TM_MEMSET:
2046 CASE_BUILT_IN_TM_STORE (1):
2047 CASE_BUILT_IN_TM_STORE (2):
2048 CASE_BUILT_IN_TM_STORE (4):
2049 CASE_BUILT_IN_TM_STORE (8):
2050 CASE_BUILT_IN_TM_STORE (FLOAT):
2051 CASE_BUILT_IN_TM_STORE (DOUBLE):
2052 CASE_BUILT_IN_TM_STORE (LDOUBLE):
2053 CASE_BUILT_IN_TM_STORE (M64):
2054 CASE_BUILT_IN_TM_STORE (M128):
2055 CASE_BUILT_IN_TM_STORE (M256):
2056 case BUILT_IN_TM_MEMCPY:
2057 case BUILT_IN_TM_MEMMOVE:
2058 {
2059 ao_ref dref;
2060 tree size = NULL_TREE;
2061 /* Don't pass in size for strncat, as the maximum size
2062 is strlen (dest) + n + 1 instead of n, resp.
2063 n + 1 at dest + strlen (dest), but strlen (dest) isn't
2064 known. */
2065 if (gimple_call_num_args (call) == 3
2066 && DECL_FUNCTION_CODE (callee) != BUILT_IN_STRNCAT)
2067 size = gimple_call_arg (call, 2);
2068 ao_ref_init_from_ptr_and_size (&dref,
2069 gimple_call_arg (call, 0),
2070 size);
2071 return refs_may_alias_p_1 (&dref, ref, false);
2072 }
2073 case BUILT_IN_STRCPY_CHK:
2074 case BUILT_IN_STRNCPY_CHK:
2075 case BUILT_IN_MEMCPY_CHK:
2076 case BUILT_IN_MEMMOVE_CHK:
2077 case BUILT_IN_MEMPCPY_CHK:
2078 case BUILT_IN_STPCPY_CHK:
2079 case BUILT_IN_STPNCPY_CHK:
2080 case BUILT_IN_STRCAT_CHK:
2081 case BUILT_IN_STRNCAT_CHK:
2082 case BUILT_IN_MEMSET_CHK:
2083 {
2084 ao_ref dref;
2085 tree size = NULL_TREE;
2086 /* Don't pass in size for __strncat_chk, as the maximum size
2087 is strlen (dest) + n + 1 instead of n, resp.
2088 n + 1 at dest + strlen (dest), but strlen (dest) isn't
2089 known. */
2090 if (gimple_call_num_args (call) == 4
2091 && DECL_FUNCTION_CODE (callee) != BUILT_IN_STRNCAT_CHK)
2092 size = gimple_call_arg (call, 2);
2093 ao_ref_init_from_ptr_and_size (&dref,
2094 gimple_call_arg (call, 0),
2095 size);
2096 return refs_may_alias_p_1 (&dref, ref, false);
2097 }
2098 case BUILT_IN_BCOPY:
2099 {
2100 ao_ref dref;
2101 tree size = gimple_call_arg (call, 2);
2102 ao_ref_init_from_ptr_and_size (&dref,
2103 gimple_call_arg (call, 1),
2104 size);
2105 return refs_may_alias_p_1 (&dref, ref, false);
2106 }
2107 /* Allocating memory does not have any side-effects apart from
2108 being the definition point for the pointer. */
2109 case BUILT_IN_MALLOC:
2110 case BUILT_IN_ALIGNED_ALLOC:
2111 case BUILT_IN_CALLOC:
2112 case BUILT_IN_STRDUP:
2113 case BUILT_IN_STRNDUP:
2114 /* Unix98 specifies that errno is set on allocation failure. */
2115 if (flag_errno_math
2116 && targetm.ref_may_alias_errno (ref))
2117 return true;
2118 return false;
2119 case BUILT_IN_STACK_SAVE:
2120 CASE_BUILT_IN_ALLOCA:
2121 case BUILT_IN_ASSUME_ALIGNED:
2122 return false;
2123 /* But posix_memalign stores a pointer into the memory pointed to
2124 by its first argument. */
2125 case BUILT_IN_POSIX_MEMALIGN:
2126 {
2127 tree ptrptr = gimple_call_arg (call, 0);
2128 ao_ref dref;
2129 ao_ref_init_from_ptr_and_size (&dref, ptrptr,
2130 TYPE_SIZE_UNIT (ptr_type_node));
2131 return (refs_may_alias_p_1 (&dref, ref, false)
2132 || (flag_errno_math
2133 && targetm.ref_may_alias_errno (ref)));
2134 }
2135 /* Freeing memory kills the pointed-to memory. More importantly
2136 the call has to serve as a barrier for moving loads and stores
2137 across it. */
2138 case BUILT_IN_FREE:
2139 case BUILT_IN_VA_END:
2140 {
2141 tree ptr = gimple_call_arg (call, 0);
2142 return ptr_deref_may_alias_ref_p_1 (ptr, ref);
2143 }
2144 /* Realloc serves both as allocation point and deallocation point. */
2145 case BUILT_IN_REALLOC:
2146 {
2147 tree ptr = gimple_call_arg (call, 0);
2148 /* Unix98 specifies that errno is set on allocation failure. */
2149 return ((flag_errno_math
2150 && targetm.ref_may_alias_errno (ref))
2151 || ptr_deref_may_alias_ref_p_1 (ptr, ref));
2152 }
2153 case BUILT_IN_GAMMA_R:
2154 case BUILT_IN_GAMMAF_R:
2155 case BUILT_IN_GAMMAL_R:
2156 case BUILT_IN_LGAMMA_R:
2157 case BUILT_IN_LGAMMAF_R:
2158 case BUILT_IN_LGAMMAL_R:
2159 {
2160 tree out = gimple_call_arg (call, 1);
2161 if (ptr_deref_may_alias_ref_p_1 (out, ref))
2162 return true;
2163 if (flag_errno_math)
2164 break;
2165 return false;
2166 }
2167 case BUILT_IN_FREXP:
2168 case BUILT_IN_FREXPF:
2169 case BUILT_IN_FREXPL:
2170 case BUILT_IN_MODF:
2171 case BUILT_IN_MODFF:
2172 case BUILT_IN_MODFL:
2173 {
2174 tree out = gimple_call_arg (call, 1);
2175 return ptr_deref_may_alias_ref_p_1 (out, ref);
2176 }
2177 case BUILT_IN_REMQUO:
2178 case BUILT_IN_REMQUOF:
2179 case BUILT_IN_REMQUOL:
2180 {
2181 tree out = gimple_call_arg (call, 2);
2182 if (ptr_deref_may_alias_ref_p_1 (out, ref))
2183 return true;
2184 if (flag_errno_math)
2185 break;
2186 return false;
2187 }
2188 case BUILT_IN_SINCOS:
2189 case BUILT_IN_SINCOSF:
2190 case BUILT_IN_SINCOSL:
2191 {
2192 tree sin = gimple_call_arg (call, 1);
2193 tree cos = gimple_call_arg (call, 2);
2194 return (ptr_deref_may_alias_ref_p_1 (sin, ref)
2195 || ptr_deref_may_alias_ref_p_1 (cos, ref));
2196 }
2197 /* __sync_* builtins and some OpenMP builtins act as threading
2198 barriers. */
2199#undef DEF_SYNC_BUILTIN
2200#define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM:
2201#include "sync-builtins.def"
2202#undef DEF_SYNC_BUILTIN
2203 case BUILT_IN_GOMP_ATOMIC_START:
2204 case BUILT_IN_GOMP_ATOMIC_END:
2205 case BUILT_IN_GOMP_BARRIER:
2206 case BUILT_IN_GOMP_BARRIER_CANCEL:
2207 case BUILT_IN_GOMP_TASKWAIT:
2208 case BUILT_IN_GOMP_TASKGROUP_END:
2209 case BUILT_IN_GOMP_CRITICAL_START:
2210 case BUILT_IN_GOMP_CRITICAL_END:
2211 case BUILT_IN_GOMP_CRITICAL_NAME_START:
2212 case BUILT_IN_GOMP_CRITICAL_NAME_END:
2213 case BUILT_IN_GOMP_LOOP_END:
2214 case BUILT_IN_GOMP_LOOP_END_CANCEL:
2215 case BUILT_IN_GOMP_ORDERED_START:
2216 case BUILT_IN_GOMP_ORDERED_END:
2217 case BUILT_IN_GOMP_SECTIONS_END:
2218 case BUILT_IN_GOMP_SECTIONS_END_CANCEL:
2219 case BUILT_IN_GOMP_SINGLE_COPY_START:
2220 case BUILT_IN_GOMP_SINGLE_COPY_END:
2221 return true;
2222 default:
2223 /* Fallthru to general call handling. */;
2224 }
2225
2226 /* Check if base is a global static variable that is not written
2227 by the function. */
2228 if (callee != NULL_TREE && VAR_P (base) && TREE_STATIC (base))
2229 {
2230 struct cgraph_node *node = cgraph_node::get (callee);
2231 bitmap not_written;
2232
2233 if (node
2234 && (not_written = ipa_reference_get_not_written_global (node))
2235 && bitmap_bit_p (not_written, ipa_reference_var_uid (base)))
2236 return false;
2237 }
2238
2239 /* Check if the base variable is call-clobbered. */
2240 if (DECL_P (base))
2241 return pt_solution_includes (gimple_call_clobber_set (call), base);
2242 else if ((TREE_CODE (base) == MEM_REF
2243 || TREE_CODE (base) == TARGET_MEM_REF)
2244 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
2245 {
2246 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
2247 if (!pi)
2248 return true;
2249
2250 return pt_solutions_intersect (gimple_call_clobber_set (call), &pi->pt);
2251 }
2252
2253 return true;
2254}
2255
2256/* If the call in statement CALL may clobber the memory reference REF
2257 return true, otherwise return false. */
2258
2259bool
2260call_may_clobber_ref_p (gcall *call, tree ref)
2261{
2262 bool res;
2263 ao_ref r;
2264 ao_ref_init (&r, ref);
2265 res = call_may_clobber_ref_p_1 (call, &r);
2266 if (res)
2267 ++alias_stats.call_may_clobber_ref_p_may_alias;
2268 else
2269 ++alias_stats.call_may_clobber_ref_p_no_alias;
2270 return res;
2271}
2272
2273
2274/* If the statement STMT may clobber the memory reference REF return true,
2275 otherwise return false. */
2276
2277bool
2278stmt_may_clobber_ref_p_1 (gimple *stmt, ao_ref *ref)
2279{
2280 if (is_gimple_call (stmt))
2281 {
2282 tree lhs = gimple_call_lhs (stmt);
2283 if (lhs
2284 && TREE_CODE (lhs) != SSA_NAME)
2285 {
2286 ao_ref r;
2287 ao_ref_init (&r, lhs);
2288 if (refs_may_alias_p_1 (ref, &r, true))
2289 return true;
2290 }
2291
2292 return call_may_clobber_ref_p_1 (as_a <gcall *> (stmt), ref);
2293 }
2294 else if (gimple_assign_single_p (stmt))
2295 {
2296 tree lhs = gimple_assign_lhs (stmt);
2297 if (TREE_CODE (lhs) != SSA_NAME)
2298 {
2299 ao_ref r;
2300 ao_ref_init (&r, lhs);
2301 return refs_may_alias_p_1 (ref, &r, true);
2302 }
2303 }
2304 else if (gimple_code (stmt) == GIMPLE_ASM)
2305 return true;
2306
2307 return false;
2308}
2309
2310bool
2311stmt_may_clobber_ref_p (gimple *stmt, tree ref)
2312{
2313 ao_ref r;
2314 ao_ref_init (&r, ref);
2315 return stmt_may_clobber_ref_p_1 (stmt, &r);
2316}
2317
2318/* Return true if store1 and store2 described by corresponding tuples
2319 <BASE, OFFSET, SIZE, MAX_SIZE> have the same size and store to the same
2320 address. */
2321
2322static bool
2323same_addr_size_stores_p (tree base1, HOST_WIDE_INT offset1, HOST_WIDE_INT size1,
2324 HOST_WIDE_INT max_size1,
2325 tree base2, HOST_WIDE_INT offset2, HOST_WIDE_INT size2,
2326 HOST_WIDE_INT max_size2)
2327{
2328 /* Offsets need to be 0. */
2329 if (offset1 != 0
2330 || offset2 != 0)
2331 return false;
2332
2333 bool base1_obj_p = SSA_VAR_P (base1);
2334 bool base2_obj_p = SSA_VAR_P (base2);
2335
2336 /* We need one object. */
2337 if (base1_obj_p == base2_obj_p)
2338 return false;
2339 tree obj = base1_obj_p ? base1 : base2;
2340
2341 /* And we need one MEM_REF. */
2342 bool base1_memref_p = TREE_CODE (base1) == MEM_REF;
2343 bool base2_memref_p = TREE_CODE (base2) == MEM_REF;
2344 if (base1_memref_p == base2_memref_p)
2345 return false;
2346 tree memref = base1_memref_p ? base1 : base2;
2347
2348 /* Sizes need to be valid. */
2349 if (max_size1 == -1 || max_size2 == -1
2350 || size1 == -1 || size2 == -1)
2351 return false;
2352
2353 /* Max_size needs to match size. */
2354 if (max_size1 != size1
2355 || max_size2 != size2)
2356 return false;
2357
2358 /* Sizes need to match. */
2359 if (size1 != size2)
2360 return false;
2361
2362
2363 /* Check that memref is a store to pointer with singleton points-to info. */
2364 if (!integer_zerop (TREE_OPERAND (memref, 1)))
2365 return false;
2366 tree ptr = TREE_OPERAND (memref, 0);
2367 if (TREE_CODE (ptr) != SSA_NAME)
2368 return false;
2369 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
2370 unsigned int pt_uid;
2371 if (pi == NULL
2372 || !pt_solution_singleton_or_null_p (&pi->pt, &pt_uid))
2373 return false;
2374
2375 /* Be conservative with non-call exceptions when the address might
2376 be NULL. */
2377 if (flag_non_call_exceptions && pi->pt.null)
2378 return false;
2379
2380 /* Check that ptr points relative to obj. */
2381 unsigned int obj_uid = DECL_PT_UID (obj);
2382 if (obj_uid != pt_uid)
2383 return false;
2384
2385 /* Check that the object size is the same as the store size. That ensures us
2386 that ptr points to the start of obj. */
2387 if (!tree_fits_shwi_p (DECL_SIZE (obj)))
2388 return false;
2389 HOST_WIDE_INT obj_size = tree_to_shwi (DECL_SIZE (obj));
2390 return obj_size == size1;
2391}
2392
2393/* If STMT kills the memory reference REF return true, otherwise
2394 return false. */
2395
2396bool
2397stmt_kills_ref_p (gimple *stmt, ao_ref *ref)
2398{
2399 if (!ao_ref_base (ref))
2400 return false;
2401
2402 if (gimple_has_lhs (stmt)
2403 && TREE_CODE (gimple_get_lhs (stmt)) != SSA_NAME
2404 /* The assignment is not necessarily carried out if it can throw
2405 and we can catch it in the current function where we could inspect
2406 the previous value.
2407 ??? We only need to care about the RHS throwing. For aggregate
2408 assignments or similar calls and non-call exceptions the LHS
2409 might throw as well. */
2410 && !stmt_can_throw_internal (stmt))
2411 {
2412 tree lhs = gimple_get_lhs (stmt);
2413 /* If LHS is literally a base of the access we are done. */
2414 if (ref->ref)
2415 {
2416 tree base = ref->ref;
2417 tree innermost_dropped_array_ref = NULL_TREE;
2418 if (handled_component_p (base))
2419 {
2420 tree saved_lhs0 = NULL_TREE;
2421 if (handled_component_p (lhs))
2422 {
2423 saved_lhs0 = TREE_OPERAND (lhs, 0);
2424 TREE_OPERAND (lhs, 0) = integer_zero_node;
2425 }
2426 do
2427 {
2428 /* Just compare the outermost handled component, if
2429 they are equal we have found a possible common
2430 base. */
2431 tree saved_base0 = TREE_OPERAND (base, 0);
2432 TREE_OPERAND (base, 0) = integer_zero_node;
2433 bool res = operand_equal_p (lhs, base, 0);
2434 TREE_OPERAND (base, 0) = saved_base0;
2435 if (res)
2436 break;
2437 /* Remember if we drop an array-ref that we need to
2438 double-check not being at struct end. */
2439 if (TREE_CODE (base) == ARRAY_REF
2440 || TREE_CODE (base) == ARRAY_RANGE_REF)
2441 innermost_dropped_array_ref = base;
2442 /* Otherwise drop handled components of the access. */
2443 base = saved_base0;
2444 }
2445 while (handled_component_p (base));
2446 if (saved_lhs0)
2447 TREE_OPERAND (lhs, 0) = saved_lhs0;
2448 }
2449 /* Finally check if the lhs has the same address and size as the
2450 base candidate of the access. Watch out if we have dropped
2451 an array-ref that was at struct end, this means ref->ref may
2452 be outside of the TYPE_SIZE of its base. */
2453 if ((! innermost_dropped_array_ref
2454 || ! array_at_struct_end_p (innermost_dropped_array_ref))
2455 && (lhs == base
2456 || (((TYPE_SIZE (TREE_TYPE (lhs))
2457 == TYPE_SIZE (TREE_TYPE (base)))
2458 || (TYPE_SIZE (TREE_TYPE (lhs))
2459 && TYPE_SIZE (TREE_TYPE (base))
2460 && operand_equal_p (TYPE_SIZE (TREE_TYPE (lhs)),
2461 TYPE_SIZE (TREE_TYPE (base)),
2462 0)))
2463 && operand_equal_p (lhs, base,
2464 OEP_ADDRESS_OF
2465 | OEP_MATCH_SIDE_EFFECTS))))
2466 return true;
2467 }
2468
2469 /* Now look for non-literal equal bases with the restriction of
2470 handling constant offset and size. */
2471 /* For a must-alias check we need to be able to constrain
2472 the access properly. */
2473 if (ref->max_size == -1)
2474 return false;
2475 HOST_WIDE_INT size, offset, max_size, ref_offset = ref->offset;
2476 bool reverse;
2477 tree base
2478 = get_ref_base_and_extent (lhs, &offset, &size, &max_size, &reverse);
2479 /* We can get MEM[symbol: sZ, index: D.8862_1] here,
2480 so base == ref->base does not always hold. */
2481 if (base != ref->base)
2482 {
2483 /* Try using points-to info. */
2484 if (same_addr_size_stores_p (base, offset, size, max_size, ref->base,
2485 ref->offset, ref->size, ref->max_size))
2486 return true;
2487
2488 /* If both base and ref->base are MEM_REFs, only compare the
2489 first operand, and if the second operand isn't equal constant,
2490 try to add the offsets into offset and ref_offset. */
2491 if (TREE_CODE (base) == MEM_REF && TREE_CODE (ref->base) == MEM_REF
2492 && TREE_OPERAND (base, 0) == TREE_OPERAND (ref->base, 0))
2493 {
2494 if (!tree_int_cst_equal (TREE_OPERAND (base, 1),
2495 TREE_OPERAND (ref->base, 1)))
2496 {
2497 offset_int off1 = mem_ref_offset (base);
2498 off1 <<= LOG2_BITS_PER_UNIT;
2499 off1 += offset;
2500 offset_int off2 = mem_ref_offset (ref->base);
2501 off2 <<= LOG2_BITS_PER_UNIT;
2502 off2 += ref_offset;
2503 if (wi::fits_shwi_p (off1) && wi::fits_shwi_p (off2))
2504 {
2505 offset = off1.to_shwi ();
2506 ref_offset = off2.to_shwi ();
2507 }
2508 else
2509 size = -1;
2510 }
2511 }
2512 else
2513 size = -1;
2514 }
2515 /* For a must-alias check we need to be able to constrain
2516 the access properly. */
2517 if (size != -1 && size == max_size)
2518 {
2519 if (offset <= ref_offset
2520 && offset + size >= ref_offset + ref->max_size)
2521 return true;
2522 }
2523 }
2524
2525 if (is_gimple_call (stmt))
2526 {
2527 tree callee = gimple_call_fndecl (stmt);
2528 if (callee != NULL_TREE
2529 && gimple_call_builtin_p (stmt, BUILT_IN_NORMAL))
2530 switch (DECL_FUNCTION_CODE (callee))
2531 {
2532 case BUILT_IN_FREE:
2533 {
2534 tree ptr = gimple_call_arg (stmt, 0);
2535 tree base = ao_ref_base (ref);
2536 if (base && TREE_CODE (base) == MEM_REF
2537 && TREE_OPERAND (base, 0) == ptr)
2538 return true;
2539 break;
2540 }
2541
2542 case BUILT_IN_MEMCPY:
2543 case BUILT_IN_MEMPCPY:
2544 case BUILT_IN_MEMMOVE:
2545 case BUILT_IN_MEMSET:
2546 case BUILT_IN_MEMCPY_CHK:
2547 case BUILT_IN_MEMPCPY_CHK:
2548 case BUILT_IN_MEMMOVE_CHK:
2549 case BUILT_IN_MEMSET_CHK:
2550 case BUILT_IN_STRNCPY:
2551 case BUILT_IN_STPNCPY:
2552 {
2553 /* For a must-alias check we need to be able to constrain
2554 the access properly. */
2555 if (ref->max_size == -1)
2556 return false;
2557 tree dest = gimple_call_arg (stmt, 0);
2558 tree len = gimple_call_arg (stmt, 2);
2559 if (!tree_fits_shwi_p (len))
2560 return false;
2561 tree rbase = ref->base;
2562 offset_int roffset = ref->offset;
2563 ao_ref dref;
2564 ao_ref_init_from_ptr_and_size (&dref, dest, len);
2565 tree base = ao_ref_base (&dref);
2566 offset_int offset = dref.offset;
2567 if (!base || dref.size == -1)
2568 return false;
2569 if (TREE_CODE (base) == MEM_REF)
2570 {
2571 if (TREE_CODE (rbase) != MEM_REF)
2572 return false;
2573 // Compare pointers.
2574 offset += mem_ref_offset (base) << LOG2_BITS_PER_UNIT;
2575 roffset += mem_ref_offset (rbase) << LOG2_BITS_PER_UNIT;
2576 base = TREE_OPERAND (base, 0);
2577 rbase = TREE_OPERAND (rbase, 0);
2578 }
2579 if (base == rbase
2580 && offset <= roffset
2581 && (roffset + ref->max_size
2582 <= offset + (wi::to_offset (len) << LOG2_BITS_PER_UNIT)))
2583 return true;
2584 break;
2585 }
2586
2587 case BUILT_IN_VA_END:
2588 {
2589 tree ptr = gimple_call_arg (stmt, 0);
2590 if (TREE_CODE (ptr) == ADDR_EXPR)
2591 {
2592 tree base = ao_ref_base (ref);
2593 if (TREE_OPERAND (ptr, 0) == base)
2594 return true;
2595 }
2596 break;
2597 }
2598
2599 default:;
2600 }
2601 }
2602 return false;
2603}
2604
2605bool
2606stmt_kills_ref_p (gimple *stmt, tree ref)
2607{
2608 ao_ref r;
2609 ao_ref_init (&r, ref);
2610 return stmt_kills_ref_p (stmt, &r);
2611}
2612
2613
2614/* Walk the virtual use-def chain of VUSE until hitting the virtual operand
2615 TARGET or a statement clobbering the memory reference REF in which
2616 case false is returned. The walk starts with VUSE, one argument of PHI. */
2617
2618static bool
2619maybe_skip_until (gimple *phi, tree target, ao_ref *ref,
2620 tree vuse, unsigned int *cnt, bitmap *visited,
2621 bool abort_on_visited,
2622 void *(*translate)(ao_ref *, tree, void *, bool *),
2623 void *data)
2624{
2625 basic_block bb = gimple_bb (phi);
2626
2627 if (!*visited)
2628 *visited = BITMAP_ALLOC (NULL);
2629
2630 bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi)));
2631
2632 /* Walk until we hit the target. */
2633 while (vuse != target)
2634 {
2635 gimple *def_stmt = SSA_NAME_DEF_STMT (vuse);
2636 /* Recurse for PHI nodes. */
2637 if (gimple_code (def_stmt) == GIMPLE_PHI)
2638 {
2639 /* An already visited PHI node ends the walk successfully. */
2640 if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt))))
2641 return !abort_on_visited;
2642 vuse = get_continuation_for_phi (def_stmt, ref, cnt,
2643 visited, abort_on_visited,
2644 translate, data);
2645 if (!vuse)
2646 return false;
2647 continue;
2648 }
2649 else if (gimple_nop_p (def_stmt))
2650 return false;
2651 else
2652 {
2653 /* A clobbering statement or the end of the IL ends it failing. */
2654 ++*cnt;
2655 if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
2656 {
2657 bool disambiguate_only = true;
2658 if (translate
2659 && (*translate) (ref, vuse, data, &disambiguate_only) == NULL)
2660 ;
2661 else
2662 return false;
2663 }
2664 }
2665 /* If we reach a new basic-block see if we already skipped it
2666 in a previous walk that ended successfully. */
2667 if (gimple_bb (def_stmt) != bb)
2668 {
2669 if (!bitmap_set_bit (*visited, SSA_NAME_VERSION (vuse)))
2670 return !abort_on_visited;
2671 bb = gimple_bb (def_stmt);
2672 }
2673 vuse = gimple_vuse (def_stmt);
2674 }
2675 return true;
2676}
2677
2678
2679/* Starting from a PHI node for the virtual operand of the memory reference
2680 REF find a continuation virtual operand that allows to continue walking
2681 statements dominating PHI skipping only statements that cannot possibly
2682 clobber REF. Increments *CNT for each alias disambiguation done.
2683 Returns NULL_TREE if no suitable virtual operand can be found. */
2684
2685tree
2686get_continuation_for_phi (gimple *phi, ao_ref *ref,
2687 unsigned int *cnt, bitmap *visited,
2688 bool abort_on_visited,
2689 void *(*translate)(ao_ref *, tree, void *, bool *),
2690 void *data)
2691{
2692 unsigned nargs = gimple_phi_num_args (phi);
2693
2694 /* Through a single-argument PHI we can simply look through. */
2695 if (nargs == 1)
2696 return PHI_ARG_DEF (phi, 0);
2697
2698 /* For two or more arguments try to pairwise skip non-aliasing code
2699 until we hit the phi argument definition that dominates the other one. */
2700 basic_block phi_bb = gimple_bb (phi);
2701 tree arg0, arg1;
2702 unsigned i;
2703
2704 /* Find a candidate for the virtual operand which definition
2705 dominates those of all others. */
2706 /* First look if any of the args themselves satisfy this. */
2707 for (i = 0; i < nargs; ++i)
2708 {
2709 arg0 = PHI_ARG_DEF (phi, i);
2710 if (SSA_NAME_IS_DEFAULT_DEF (arg0))
2711 break;
2712 basic_block def_bb = gimple_bb (SSA_NAME_DEF_STMT (arg0));
2713 if (def_bb != phi_bb
2714 && dominated_by_p (CDI_DOMINATORS, phi_bb, def_bb))
2715 break;
2716 arg0 = NULL_TREE;
2717 }
2718 /* If not, look if we can reach such candidate by walking defs
2719 of a PHI arg without crossing other PHIs. */
2720 if (! arg0)
2721 for (i = 0; i < nargs; ++i)
2722 {
2723 arg0 = PHI_ARG_DEF (phi, i);
2724 gimple *def = SSA_NAME_DEF_STMT (arg0);
2725 /* Backedges can't work. */
2726 if (dominated_by_p (CDI_DOMINATORS,
2727 gimple_bb (def), phi_bb))
2728 continue;
2729 /* See below. */
2730 if (gimple_code (def) == GIMPLE_PHI)
2731 continue;
2732 while (! dominated_by_p (CDI_DOMINATORS,
2733 phi_bb, gimple_bb (def)))
2734 {
2735 arg0 = gimple_vuse (def);
2736 if (SSA_NAME_IS_DEFAULT_DEF (arg0))
2737 break;
2738 def = SSA_NAME_DEF_STMT (arg0);
2739 if (gimple_code (def) == GIMPLE_PHI)
2740 {
2741 /* Do not try to look through arbitrarily complicated
2742 CFGs. For those looking for the first VUSE starting
2743 from the end of the immediate dominator of phi_bb
2744 is likely faster. */
2745 arg0 = NULL_TREE;
2746 goto next;
2747 }
2748 }
2749 break;
2750next:;
2751 }
2752 if (! arg0)
2753 return NULL_TREE;
2754
2755 /* Then check against the found candidate. */
2756 for (i = 0; i < nargs; ++i)
2757 {
2758 arg1 = PHI_ARG_DEF (phi, i);
2759 if (arg1 == arg0)
2760 ;
2761 else if (! maybe_skip_until (phi, arg0, ref, arg1, cnt, visited,
2762 abort_on_visited, translate, data))
2763 return NULL_TREE;
2764 }
2765
2766 return arg0;
2767}
2768
2769/* Based on the memory reference REF and its virtual use VUSE call
2770 WALKER for each virtual use that is equivalent to VUSE, including VUSE
2771 itself. That is, for each virtual use for which its defining statement
2772 does not clobber REF.
2773
2774 WALKER is called with REF, the current virtual use and DATA. If
2775 WALKER returns non-NULL the walk stops and its result is returned.
2776 At the end of a non-successful walk NULL is returned.
2777
2778 TRANSLATE if non-NULL is called with a pointer to REF, the virtual
2779 use which definition is a statement that may clobber REF and DATA.
2780 If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
2781 If TRANSLATE returns non-NULL the walk stops and its result is returned.
2782 If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
2783 to adjust REF and *DATA to make that valid.
2784
2785 VALUEIZE if non-NULL is called with the next VUSE that is considered
2786 and return value is substituted for that. This can be used to
2787 implement optimistic value-numbering for example. Note that the
2788 VUSE argument is assumed to be valueized already.
2789
2790 TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
2791
2792void *
2793walk_non_aliased_vuses (ao_ref *ref, tree vuse,
2794 void *(*walker)(ao_ref *, tree, unsigned int, void *),
2795 void *(*translate)(ao_ref *, tree, void *, bool *),
2796 tree (*valueize)(tree),
2797 void *data)
2798{
2799 bitmap visited = NULL;
2800 void *res;
2801 unsigned int cnt = 0;
2802 bool translated = false;
2803
2804 timevar_push (TV_ALIAS_STMT_WALK);
2805
2806 do
2807 {
2808 gimple *def_stmt;
2809
2810 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
2811 res = (*walker) (ref, vuse, cnt, data);
2812 /* Abort walk. */
2813 if (res == (void *)-1)
2814 {
2815 res = NULL;
2816 break;
2817 }
2818 /* Lookup succeeded. */
2819 else if (res != NULL)
2820 break;
2821
2822 if (valueize)
2823 vuse = valueize (vuse);
2824 def_stmt = SSA_NAME_DEF_STMT (vuse);
2825 if (gimple_nop_p (def_stmt))
2826 break;
2827 else if (gimple_code (def_stmt) == GIMPLE_PHI)
2828 vuse = get_continuation_for_phi (def_stmt, ref, &cnt,
2829 &visited, translated, translate, data);
2830 else
2831 {
2832 cnt++;
2833 if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
2834 {
2835 if (!translate)
2836 break;
2837 bool disambiguate_only = false;
2838 res = (*translate) (ref, vuse, data, &disambiguate_only);
2839 /* Failed lookup and translation. */
2840 if (res == (void *)-1)
2841 {
2842 res = NULL;
2843 break;
2844 }
2845 /* Lookup succeeded. */
2846 else if (res != NULL)
2847 break;
2848 /* Translation succeeded, continue walking. */
2849 translated = translated || !disambiguate_only;
2850 }
2851 vuse = gimple_vuse (def_stmt);
2852 }
2853 }
2854 while (vuse);
2855
2856 if (visited)
2857 BITMAP_FREE (visited);
2858
2859 timevar_pop (TV_ALIAS_STMT_WALK);
2860
2861 return res;
2862}
2863
2864
2865/* Based on the memory reference REF call WALKER for each vdef which
2866 defining statement may clobber REF, starting with VDEF. If REF
2867 is NULL_TREE, each defining statement is visited.
2868
2869 WALKER is called with REF, the current vdef and DATA. If WALKER
2870 returns true the walk is stopped, otherwise it continues.
2871
2872 If function entry is reached, FUNCTION_ENTRY_REACHED is set to true.
2873 The pointer may be NULL and then we do not track this information.
2874
2875 At PHI nodes walk_aliased_vdefs forks into one walk for reach
2876 PHI argument (but only one walk continues on merge points), the
2877 return value is true if any of the walks was successful.
2878
2879 The function returns the number of statements walked or -1 if
2880 LIMIT stmts were walked and the walk was aborted at this point.
2881 If LIMIT is zero the walk is not aborted. */
2882
2883static int
2884walk_aliased_vdefs_1 (ao_ref *ref, tree vdef,
2885 bool (*walker)(ao_ref *, tree, void *), void *data,
2886 bitmap *visited, unsigned int cnt,
2887 bool *function_entry_reached, unsigned limit)
2888{
2889 do
2890 {
2891 gimple *def_stmt = SSA_NAME_DEF_STMT (vdef);
2892
2893 if (*visited
2894 && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef)))
2895 return cnt;
2896
2897 if (gimple_nop_p (def_stmt))
2898 {
2899 if (function_entry_reached)
2900 *function_entry_reached = true;
2901 return cnt;
2902 }
2903 else if (gimple_code (def_stmt) == GIMPLE_PHI)
2904 {
2905 unsigned i;
2906 if (!*visited)
2907 *visited = BITMAP_ALLOC (NULL);
2908 for (i = 0; i < gimple_phi_num_args (def_stmt); ++i)
2909 {
2910 int res = walk_aliased_vdefs_1 (ref,
2911 gimple_phi_arg_def (def_stmt, i),
2912 walker, data, visited, cnt,
2913 function_entry_reached, limit);
2914 if (res == -1)
2915 return -1;
2916 cnt = res;
2917 }
2918 return cnt;
2919 }
2920
2921 /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
2922 cnt++;
2923 if (cnt == limit)
2924 return -1;
2925 if ((!ref
2926 || stmt_may_clobber_ref_p_1 (def_stmt, ref))
2927 && (*walker) (ref, vdef, data))
2928 return cnt;
2929
2930 vdef = gimple_vuse (def_stmt);
2931 }
2932 while (1);
2933}
2934
2935int
2936walk_aliased_vdefs (ao_ref *ref, tree vdef,
2937 bool (*walker)(ao_ref *, tree, void *), void *data,
2938 bitmap *visited,
2939 bool *function_entry_reached, unsigned int limit)
2940{
2941 bitmap local_visited = NULL;
2942 int ret;
2943
2944 timevar_push (TV_ALIAS_STMT_WALK);
2945
2946 if (function_entry_reached)
2947 *function_entry_reached = false;
2948
2949 ret = walk_aliased_vdefs_1 (ref, vdef, walker, data,
2950 visited ? visited : &local_visited, 0,
2951 function_entry_reached, limit);
2952 if (local_visited)
2953 BITMAP_FREE (local_visited);
2954
2955 timevar_pop (TV_ALIAS_STMT_WALK);
2956
2957 return ret;
2958}
2959
2960