Fix ChangeLog record for 171649:
[official-gcc.git] / gcc / alias.c
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1 /* Alias analysis for GNU C
2 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
3 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
4 Contributed by John Carr (jfc@mit.edu).
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
11 version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 #include "config.h"
23 #include "system.h"
24 #include "coretypes.h"
25 #include "tm.h"
26 #include "rtl.h"
27 #include "tree.h"
28 #include "tm_p.h"
29 #include "function.h"
30 #include "alias.h"
31 #include "emit-rtl.h"
32 #include "regs.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
35 #include "flags.h"
36 #include "output.h"
37 #include "diagnostic-core.h"
38 #include "cselib.h"
39 #include "splay-tree.h"
40 #include "ggc.h"
41 #include "langhooks.h"
42 #include "timevar.h"
43 #include "target.h"
44 #include "cgraph.h"
45 #include "tree-pass.h"
46 #include "df.h"
47 #include "tree-ssa-alias.h"
48 #include "pointer-set.h"
49 #include "tree-flow.h"
51 /* The aliasing API provided here solves related but different problems:
53 Say there exists (in c)
55 struct X {
56 struct Y y1;
57 struct Z z2;
58 } x1, *px1, *px2;
60 struct Y y2, *py;
61 struct Z z2, *pz;
64 py = &px1.y1;
65 px2 = &x1;
67 Consider the four questions:
69 Can a store to x1 interfere with px2->y1?
70 Can a store to x1 interfere with px2->z2?
71 (*px2).z2
72 Can a store to x1 change the value pointed to by with py?
73 Can a store to x1 change the value pointed to by with pz?
75 The answer to these questions can be yes, yes, yes, and maybe.
77 The first two questions can be answered with a simple examination
78 of the type system. If structure X contains a field of type Y then
79 a store thru a pointer to an X can overwrite any field that is
80 contained (recursively) in an X (unless we know that px1 != px2).
82 The last two of the questions can be solved in the same way as the
83 first two questions but this is too conservative. The observation
84 is that in some cases analysis we can know if which (if any) fields
85 are addressed and if those addresses are used in bad ways. This
86 analysis may be language specific. In C, arbitrary operations may
87 be applied to pointers. However, there is some indication that
88 this may be too conservative for some C++ types.
90 The pass ipa-type-escape does this analysis for the types whose
91 instances do not escape across the compilation boundary.
93 Historically in GCC, these two problems were combined and a single
94 data structure was used to represent the solution to these
95 problems. We now have two similar but different data structures,
96 The data structure to solve the last two question is similar to the
97 first, but does not contain have the fields in it whose address are
98 never taken. For types that do escape the compilation unit, the
99 data structures will have identical information.
102 /* The alias sets assigned to MEMs assist the back-end in determining
103 which MEMs can alias which other MEMs. In general, two MEMs in
104 different alias sets cannot alias each other, with one important
105 exception. Consider something like:
107 struct S { int i; double d; };
109 a store to an `S' can alias something of either type `int' or type
110 `double'. (However, a store to an `int' cannot alias a `double'
111 and vice versa.) We indicate this via a tree structure that looks
112 like:
113 struct S
116 |/_ _\|
117 int double
119 (The arrows are directed and point downwards.)
120 In this situation we say the alias set for `struct S' is the
121 `superset' and that those for `int' and `double' are `subsets'.
123 To see whether two alias sets can point to the same memory, we must
124 see if either alias set is a subset of the other. We need not trace
125 past immediate descendants, however, since we propagate all
126 grandchildren up one level.
128 Alias set zero is implicitly a superset of all other alias sets.
129 However, this is no actual entry for alias set zero. It is an
130 error to attempt to explicitly construct a subset of zero. */
132 struct GTY(()) alias_set_entry_d {
133 /* The alias set number, as stored in MEM_ALIAS_SET. */
134 alias_set_type alias_set;
136 /* Nonzero if would have a child of zero: this effectively makes this
137 alias set the same as alias set zero. */
138 int has_zero_child;
140 /* The children of the alias set. These are not just the immediate
141 children, but, in fact, all descendants. So, if we have:
143 struct T { struct S s; float f; }
145 continuing our example above, the children here will be all of
146 `int', `double', `float', and `struct S'. */
147 splay_tree GTY((param1_is (int), param2_is (int))) children;
149 typedef struct alias_set_entry_d *alias_set_entry;
151 static int rtx_equal_for_memref_p (const_rtx, const_rtx);
152 static int memrefs_conflict_p (int, rtx, int, rtx, HOST_WIDE_INT);
153 static void record_set (rtx, const_rtx, void *);
154 static int base_alias_check (rtx, rtx, enum machine_mode,
155 enum machine_mode);
156 static rtx find_base_value (rtx);
157 static int mems_in_disjoint_alias_sets_p (const_rtx, const_rtx);
158 static int insert_subset_children (splay_tree_node, void*);
159 static alias_set_entry get_alias_set_entry (alias_set_type);
160 static int aliases_everything_p (const_rtx);
161 static bool nonoverlapping_component_refs_p (const_tree, const_tree);
162 static tree decl_for_component_ref (tree);
163 static int write_dependence_p (const_rtx, const_rtx, int);
165 static void memory_modified_1 (rtx, const_rtx, void *);
167 /* Set up all info needed to perform alias analysis on memory references. */
169 /* Returns the size in bytes of the mode of X. */
170 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
172 /* Returns nonzero if MEM1 and MEM2 do not alias because they are in
173 different alias sets. We ignore alias sets in functions making use
174 of variable arguments because the va_arg macros on some systems are
175 not legal ANSI C. */
176 #define DIFFERENT_ALIAS_SETS_P(MEM1, MEM2) \
177 mems_in_disjoint_alias_sets_p (MEM1, MEM2)
179 /* Cap the number of passes we make over the insns propagating alias
180 information through set chains. 10 is a completely arbitrary choice. */
181 #define MAX_ALIAS_LOOP_PASSES 10
183 /* reg_base_value[N] gives an address to which register N is related.
184 If all sets after the first add or subtract to the current value
185 or otherwise modify it so it does not point to a different top level
186 object, reg_base_value[N] is equal to the address part of the source
187 of the first set.
189 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
190 expressions represent certain special values: function arguments and
191 the stack, frame, and argument pointers.
193 The contents of an ADDRESS is not normally used, the mode of the
194 ADDRESS determines whether the ADDRESS is a function argument or some
195 other special value. Pointer equality, not rtx_equal_p, determines whether
196 two ADDRESS expressions refer to the same base address.
198 The only use of the contents of an ADDRESS is for determining if the
199 current function performs nonlocal memory memory references for the
200 purposes of marking the function as a constant function. */
202 static GTY(()) VEC(rtx,gc) *reg_base_value;
203 static rtx *new_reg_base_value;
205 /* We preserve the copy of old array around to avoid amount of garbage
206 produced. About 8% of garbage produced were attributed to this
207 array. */
208 static GTY((deletable)) VEC(rtx,gc) *old_reg_base_value;
210 #define static_reg_base_value \
211 (this_target_rtl->x_static_reg_base_value)
213 #define REG_BASE_VALUE(X) \
214 (REGNO (X) < VEC_length (rtx, reg_base_value) \
215 ? VEC_index (rtx, reg_base_value, REGNO (X)) : 0)
217 /* Vector indexed by N giving the initial (unchanging) value known for
218 pseudo-register N. This array is initialized in init_alias_analysis,
219 and does not change until end_alias_analysis is called. */
220 static GTY((length("reg_known_value_size"))) rtx *reg_known_value;
222 /* Indicates number of valid entries in reg_known_value. */
223 static GTY(()) unsigned int reg_known_value_size;
225 /* Vector recording for each reg_known_value whether it is due to a
226 REG_EQUIV note. Future passes (viz., reload) may replace the
227 pseudo with the equivalent expression and so we account for the
228 dependences that would be introduced if that happens.
230 The REG_EQUIV notes created in assign_parms may mention the arg
231 pointer, and there are explicit insns in the RTL that modify the
232 arg pointer. Thus we must ensure that such insns don't get
233 scheduled across each other because that would invalidate the
234 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
235 wrong, but solving the problem in the scheduler will likely give
236 better code, so we do it here. */
237 static bool *reg_known_equiv_p;
239 /* True when scanning insns from the start of the rtl to the
240 NOTE_INSN_FUNCTION_BEG note. */
241 static bool copying_arguments;
243 DEF_VEC_P(alias_set_entry);
244 DEF_VEC_ALLOC_P(alias_set_entry,gc);
246 /* The splay-tree used to store the various alias set entries. */
247 static GTY (()) VEC(alias_set_entry,gc) *alias_sets;
249 /* Build a decomposed reference object for querying the alias-oracle
250 from the MEM rtx and store it in *REF.
251 Returns false if MEM is not suitable for the alias-oracle. */
253 static bool
254 ao_ref_from_mem (ao_ref *ref, const_rtx mem)
256 tree expr = MEM_EXPR (mem);
257 tree base;
259 if (!expr)
260 return false;
262 ao_ref_init (ref, expr);
264 /* Get the base of the reference and see if we have to reject or
265 adjust it. */
266 base = ao_ref_base (ref);
267 if (base == NULL_TREE)
268 return false;
270 /* The tree oracle doesn't like to have these. */
271 if (TREE_CODE (base) == FUNCTION_DECL
272 || TREE_CODE (base) == LABEL_DECL)
273 return false;
275 /* If this is a pointer dereference of a non-SSA_NAME punt.
276 ??? We could replace it with a pointer to anything. */
277 if ((INDIRECT_REF_P (base)
278 || TREE_CODE (base) == MEM_REF)
279 && TREE_CODE (TREE_OPERAND (base, 0)) != SSA_NAME)
280 return false;
281 if (TREE_CODE (base) == TARGET_MEM_REF
282 && TMR_BASE (base)
283 && TREE_CODE (TMR_BASE (base)) != SSA_NAME)
284 return false;
286 /* If this is a reference based on a partitioned decl replace the
287 base with an INDIRECT_REF of the pointer representative we
288 created during stack slot partitioning. */
289 if (TREE_CODE (base) == VAR_DECL
290 && ! TREE_STATIC (base)
291 && cfun->gimple_df->decls_to_pointers != NULL)
293 void *namep;
294 namep = pointer_map_contains (cfun->gimple_df->decls_to_pointers, base);
295 if (namep)
296 ref->base = build_simple_mem_ref (*(tree *)namep);
298 else if (TREE_CODE (base) == TARGET_MEM_REF
299 && TREE_CODE (TMR_BASE (base)) == ADDR_EXPR
300 && TREE_CODE (TREE_OPERAND (TMR_BASE (base), 0)) == VAR_DECL
301 && ! TREE_STATIC (TREE_OPERAND (TMR_BASE (base), 0))
302 && cfun->gimple_df->decls_to_pointers != NULL)
304 void *namep;
305 namep = pointer_map_contains (cfun->gimple_df->decls_to_pointers,
306 TREE_OPERAND (TMR_BASE (base), 0));
307 if (namep)
308 ref->base = build_simple_mem_ref (*(tree *)namep);
311 ref->ref_alias_set = MEM_ALIAS_SET (mem);
313 /* If MEM_OFFSET or MEM_SIZE are unknown we have to punt.
314 Keep points-to related information though. */
315 if (!MEM_OFFSET_KNOWN_P (mem)
316 || !MEM_SIZE_KNOWN_P (mem))
318 ref->ref = NULL_TREE;
319 ref->offset = 0;
320 ref->size = -1;
321 ref->max_size = -1;
322 return true;
325 /* If the base decl is a parameter we can have negative MEM_OFFSET in
326 case of promoted subregs on bigendian targets. Trust the MEM_EXPR
327 here. */
328 if (MEM_OFFSET (mem) < 0
329 && (MEM_SIZE (mem) + MEM_OFFSET (mem)) * BITS_PER_UNIT == ref->size)
330 return true;
332 ref->offset += MEM_OFFSET (mem) * BITS_PER_UNIT;
333 ref->size = MEM_SIZE (mem) * BITS_PER_UNIT;
335 /* The MEM may extend into adjacent fields, so adjust max_size if
336 necessary. */
337 if (ref->max_size != -1
338 && ref->size > ref->max_size)
339 ref->max_size = ref->size;
341 /* If MEM_OFFSET and MEM_SIZE get us outside of the base object of
342 the MEM_EXPR punt. This happens for STRICT_ALIGNMENT targets a lot. */
343 if (MEM_EXPR (mem) != get_spill_slot_decl (false)
344 && (ref->offset < 0
345 || (DECL_P (ref->base)
346 && (!host_integerp (DECL_SIZE (ref->base), 1)
347 || (TREE_INT_CST_LOW (DECL_SIZE ((ref->base)))
348 < (unsigned HOST_WIDE_INT)(ref->offset + ref->size))))))
349 return false;
351 return true;
354 /* Query the alias-oracle on whether the two memory rtx X and MEM may
355 alias. If TBAA_P is set also apply TBAA. Returns true if the
356 two rtxen may alias, false otherwise. */
358 static bool
359 rtx_refs_may_alias_p (const_rtx x, const_rtx mem, bool tbaa_p)
361 ao_ref ref1, ref2;
363 if (!ao_ref_from_mem (&ref1, x)
364 || !ao_ref_from_mem (&ref2, mem))
365 return true;
367 return refs_may_alias_p_1 (&ref1, &ref2,
368 tbaa_p
369 && MEM_ALIAS_SET (x) != 0
370 && MEM_ALIAS_SET (mem) != 0);
373 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
374 such an entry, or NULL otherwise. */
376 static inline alias_set_entry
377 get_alias_set_entry (alias_set_type alias_set)
379 return VEC_index (alias_set_entry, alias_sets, alias_set);
382 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
383 the two MEMs cannot alias each other. */
385 static inline int
386 mems_in_disjoint_alias_sets_p (const_rtx mem1, const_rtx mem2)
388 /* Perform a basic sanity check. Namely, that there are no alias sets
389 if we're not using strict aliasing. This helps to catch bugs
390 whereby someone uses PUT_CODE, but doesn't clear MEM_ALIAS_SET, or
391 where a MEM is allocated in some way other than by the use of
392 gen_rtx_MEM, and the MEM_ALIAS_SET is not cleared. If we begin to
393 use alias sets to indicate that spilled registers cannot alias each
394 other, we might need to remove this check. */
395 gcc_assert (flag_strict_aliasing
396 || (!MEM_ALIAS_SET (mem1) && !MEM_ALIAS_SET (mem2)));
398 return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1), MEM_ALIAS_SET (mem2));
401 /* Insert the NODE into the splay tree given by DATA. Used by
402 record_alias_subset via splay_tree_foreach. */
404 static int
405 insert_subset_children (splay_tree_node node, void *data)
407 splay_tree_insert ((splay_tree) data, node->key, node->value);
409 return 0;
412 /* Return true if the first alias set is a subset of the second. */
414 bool
415 alias_set_subset_of (alias_set_type set1, alias_set_type set2)
417 alias_set_entry ase;
419 /* Everything is a subset of the "aliases everything" set. */
420 if (set2 == 0)
421 return true;
423 /* Otherwise, check if set1 is a subset of set2. */
424 ase = get_alias_set_entry (set2);
425 if (ase != 0
426 && (ase->has_zero_child
427 || splay_tree_lookup (ase->children,
428 (splay_tree_key) set1)))
429 return true;
430 return false;
433 /* Return 1 if the two specified alias sets may conflict. */
436 alias_sets_conflict_p (alias_set_type set1, alias_set_type set2)
438 alias_set_entry ase;
440 /* The easy case. */
441 if (alias_sets_must_conflict_p (set1, set2))
442 return 1;
444 /* See if the first alias set is a subset of the second. */
445 ase = get_alias_set_entry (set1);
446 if (ase != 0
447 && (ase->has_zero_child
448 || splay_tree_lookup (ase->children,
449 (splay_tree_key) set2)))
450 return 1;
452 /* Now do the same, but with the alias sets reversed. */
453 ase = get_alias_set_entry (set2);
454 if (ase != 0
455 && (ase->has_zero_child
456 || splay_tree_lookup (ase->children,
457 (splay_tree_key) set1)))
458 return 1;
460 /* The two alias sets are distinct and neither one is the
461 child of the other. Therefore, they cannot conflict. */
462 return 0;
465 /* Return 1 if the two specified alias sets will always conflict. */
468 alias_sets_must_conflict_p (alias_set_type set1, alias_set_type set2)
470 if (set1 == 0 || set2 == 0 || set1 == set2)
471 return 1;
473 return 0;
476 /* Return 1 if any MEM object of type T1 will always conflict (using the
477 dependency routines in this file) with any MEM object of type T2.
478 This is used when allocating temporary storage. If T1 and/or T2 are
479 NULL_TREE, it means we know nothing about the storage. */
482 objects_must_conflict_p (tree t1, tree t2)
484 alias_set_type set1, set2;
486 /* If neither has a type specified, we don't know if they'll conflict
487 because we may be using them to store objects of various types, for
488 example the argument and local variables areas of inlined functions. */
489 if (t1 == 0 && t2 == 0)
490 return 0;
492 /* If they are the same type, they must conflict. */
493 if (t1 == t2
494 /* Likewise if both are volatile. */
495 || (t1 != 0 && TYPE_VOLATILE (t1) && t2 != 0 && TYPE_VOLATILE (t2)))
496 return 1;
498 set1 = t1 ? get_alias_set (t1) : 0;
499 set2 = t2 ? get_alias_set (t2) : 0;
501 /* We can't use alias_sets_conflict_p because we must make sure
502 that every subtype of t1 will conflict with every subtype of
503 t2 for which a pair of subobjects of these respective subtypes
504 overlaps on the stack. */
505 return alias_sets_must_conflict_p (set1, set2);
508 /* Return true if all nested component references handled by
509 get_inner_reference in T are such that we should use the alias set
510 provided by the object at the heart of T.
512 This is true for non-addressable components (which don't have their
513 own alias set), as well as components of objects in alias set zero.
514 This later point is a special case wherein we wish to override the
515 alias set used by the component, but we don't have per-FIELD_DECL
516 assignable alias sets. */
518 bool
519 component_uses_parent_alias_set (const_tree t)
521 while (1)
523 /* If we're at the end, it vacuously uses its own alias set. */
524 if (!handled_component_p (t))
525 return false;
527 switch (TREE_CODE (t))
529 case COMPONENT_REF:
530 if (DECL_NONADDRESSABLE_P (TREE_OPERAND (t, 1)))
531 return true;
532 break;
534 case ARRAY_REF:
535 case ARRAY_RANGE_REF:
536 if (TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t, 0))))
537 return true;
538 break;
540 case REALPART_EXPR:
541 case IMAGPART_EXPR:
542 break;
544 default:
545 /* Bitfields and casts are never addressable. */
546 return true;
549 t = TREE_OPERAND (t, 0);
550 if (get_alias_set (TREE_TYPE (t)) == 0)
551 return true;
555 /* Return the alias set for the memory pointed to by T, which may be
556 either a type or an expression. Return -1 if there is nothing
557 special about dereferencing T. */
559 static alias_set_type
560 get_deref_alias_set_1 (tree t)
562 /* If we're not doing any alias analysis, just assume everything
563 aliases everything else. */
564 if (!flag_strict_aliasing)
565 return 0;
567 /* All we care about is the type. */
568 if (! TYPE_P (t))
569 t = TREE_TYPE (t);
571 /* If we have an INDIRECT_REF via a void pointer, we don't
572 know anything about what that might alias. Likewise if the
573 pointer is marked that way. */
574 if (TREE_CODE (TREE_TYPE (t)) == VOID_TYPE
575 || TYPE_REF_CAN_ALIAS_ALL (t))
576 return 0;
578 return -1;
581 /* Return the alias set for the memory pointed to by T, which may be
582 either a type or an expression. */
584 alias_set_type
585 get_deref_alias_set (tree t)
587 alias_set_type set = get_deref_alias_set_1 (t);
589 /* Fall back to the alias-set of the pointed-to type. */
590 if (set == -1)
592 if (! TYPE_P (t))
593 t = TREE_TYPE (t);
594 set = get_alias_set (TREE_TYPE (t));
597 return set;
600 /* Return the alias set for T, which may be either a type or an
601 expression. Call language-specific routine for help, if needed. */
603 alias_set_type
604 get_alias_set (tree t)
606 alias_set_type set;
608 /* If we're not doing any alias analysis, just assume everything
609 aliases everything else. Also return 0 if this or its type is
610 an error. */
611 if (! flag_strict_aliasing || t == error_mark_node
612 || (! TYPE_P (t)
613 && (TREE_TYPE (t) == 0 || TREE_TYPE (t) == error_mark_node)))
614 return 0;
616 /* We can be passed either an expression or a type. This and the
617 language-specific routine may make mutually-recursive calls to each other
618 to figure out what to do. At each juncture, we see if this is a tree
619 that the language may need to handle specially. First handle things that
620 aren't types. */
621 if (! TYPE_P (t))
623 tree inner;
625 /* Give the language a chance to do something with this tree
626 before we look at it. */
627 STRIP_NOPS (t);
628 set = lang_hooks.get_alias_set (t);
629 if (set != -1)
630 return set;
632 /* Get the base object of the reference. */
633 inner = t;
634 while (handled_component_p (inner))
636 /* If there is a VIEW_CONVERT_EXPR in the chain we cannot use
637 the type of any component references that wrap it to
638 determine the alias-set. */
639 if (TREE_CODE (inner) == VIEW_CONVERT_EXPR)
640 t = TREE_OPERAND (inner, 0);
641 inner = TREE_OPERAND (inner, 0);
644 /* Handle pointer dereferences here, they can override the
645 alias-set. */
646 if (INDIRECT_REF_P (inner))
648 set = get_deref_alias_set_1 (TREE_OPERAND (inner, 0));
649 if (set != -1)
650 return set;
652 else if (TREE_CODE (inner) == TARGET_MEM_REF)
653 return get_deref_alias_set (TMR_OFFSET (inner));
654 else if (TREE_CODE (inner) == MEM_REF)
656 set = get_deref_alias_set_1 (TREE_OPERAND (inner, 1));
657 if (set != -1)
658 return set;
661 /* If the innermost reference is a MEM_REF that has a
662 conversion embedded treat it like a VIEW_CONVERT_EXPR above,
663 using the memory access type for determining the alias-set. */
664 if (TREE_CODE (inner) == MEM_REF
665 && TYPE_MAIN_VARIANT (TREE_TYPE (inner))
666 != TYPE_MAIN_VARIANT
667 (TREE_TYPE (TREE_TYPE (TREE_OPERAND (inner, 1)))))
668 return get_deref_alias_set (TREE_OPERAND (inner, 1));
670 /* Otherwise, pick up the outermost object that we could have a pointer
671 to, processing conversions as above. */
672 while (component_uses_parent_alias_set (t))
674 t = TREE_OPERAND (t, 0);
675 STRIP_NOPS (t);
678 /* If we've already determined the alias set for a decl, just return
679 it. This is necessary for C++ anonymous unions, whose component
680 variables don't look like union members (boo!). */
681 if (TREE_CODE (t) == VAR_DECL
682 && DECL_RTL_SET_P (t) && MEM_P (DECL_RTL (t)))
683 return MEM_ALIAS_SET (DECL_RTL (t));
685 /* Now all we care about is the type. */
686 t = TREE_TYPE (t);
689 /* Variant qualifiers don't affect the alias set, so get the main
690 variant. */
691 t = TYPE_MAIN_VARIANT (t);
693 /* Always use the canonical type as well. If this is a type that
694 requires structural comparisons to identify compatible types
695 use alias set zero. */
696 if (TYPE_STRUCTURAL_EQUALITY_P (t))
698 /* Allow the language to specify another alias set for this
699 type. */
700 set = lang_hooks.get_alias_set (t);
701 if (set != -1)
702 return set;
703 return 0;
706 t = TYPE_CANONICAL (t);
708 /* The canonical type should not require structural equality checks. */
709 gcc_checking_assert (!TYPE_STRUCTURAL_EQUALITY_P (t));
711 /* If this is a type with a known alias set, return it. */
712 if (TYPE_ALIAS_SET_KNOWN_P (t))
713 return TYPE_ALIAS_SET (t);
715 /* We don't want to set TYPE_ALIAS_SET for incomplete types. */
716 if (!COMPLETE_TYPE_P (t))
718 /* For arrays with unknown size the conservative answer is the
719 alias set of the element type. */
720 if (TREE_CODE (t) == ARRAY_TYPE)
721 return get_alias_set (TREE_TYPE (t));
723 /* But return zero as a conservative answer for incomplete types. */
724 return 0;
727 /* See if the language has special handling for this type. */
728 set = lang_hooks.get_alias_set (t);
729 if (set != -1)
730 return set;
732 /* There are no objects of FUNCTION_TYPE, so there's no point in
733 using up an alias set for them. (There are, of course, pointers
734 and references to functions, but that's different.) */
735 else if (TREE_CODE (t) == FUNCTION_TYPE || TREE_CODE (t) == METHOD_TYPE)
736 set = 0;
738 /* Unless the language specifies otherwise, let vector types alias
739 their components. This avoids some nasty type punning issues in
740 normal usage. And indeed lets vectors be treated more like an
741 array slice. */
742 else if (TREE_CODE (t) == VECTOR_TYPE)
743 set = get_alias_set (TREE_TYPE (t));
745 /* Unless the language specifies otherwise, treat array types the
746 same as their components. This avoids the asymmetry we get
747 through recording the components. Consider accessing a
748 character(kind=1) through a reference to a character(kind=1)[1:1].
749 Or consider if we want to assign integer(kind=4)[0:D.1387] and
750 integer(kind=4)[4] the same alias set or not.
751 Just be pragmatic here and make sure the array and its element
752 type get the same alias set assigned. */
753 else if (TREE_CODE (t) == ARRAY_TYPE && !TYPE_NONALIASED_COMPONENT (t))
754 set = get_alias_set (TREE_TYPE (t));
756 /* From the former common C and C++ langhook implementation:
758 Unfortunately, there is no canonical form of a pointer type.
759 In particular, if we have `typedef int I', then `int *', and
760 `I *' are different types. So, we have to pick a canonical
761 representative. We do this below.
763 Technically, this approach is actually more conservative that
764 it needs to be. In particular, `const int *' and `int *'
765 should be in different alias sets, according to the C and C++
766 standard, since their types are not the same, and so,
767 technically, an `int **' and `const int **' cannot point at
768 the same thing.
770 But, the standard is wrong. In particular, this code is
771 legal C++:
773 int *ip;
774 int **ipp = &ip;
775 const int* const* cipp = ipp;
776 And, it doesn't make sense for that to be legal unless you
777 can dereference IPP and CIPP. So, we ignore cv-qualifiers on
778 the pointed-to types. This issue has been reported to the
779 C++ committee.
781 In addition to the above canonicalization issue, with LTO
782 we should also canonicalize `T (*)[]' to `T *' avoiding
783 alias issues with pointer-to element types and pointer-to
784 array types.
786 Likewise we need to deal with the situation of incomplete
787 pointed-to types and make `*(struct X **)&a' and
788 `*(struct X {} **)&a' alias. Otherwise we will have to
789 guarantee that all pointer-to incomplete type variants
790 will be replaced by pointer-to complete type variants if
791 they are available.
793 With LTO the convenient situation of using `void *' to
794 access and store any pointer type will also become
795 more apparent (and `void *' is just another pointer-to
796 incomplete type). Assigning alias-set zero to `void *'
797 and all pointer-to incomplete types is a not appealing
798 solution. Assigning an effective alias-set zero only
799 affecting pointers might be - by recording proper subset
800 relationships of all pointer alias-sets.
802 Pointer-to function types are another grey area which
803 needs caution. Globbing them all into one alias-set
804 or the above effective zero set would work.
806 For now just assign the same alias-set to all pointers.
807 That's simple and avoids all the above problems. */
808 else if (POINTER_TYPE_P (t)
809 && t != ptr_type_node)
810 set = get_alias_set (ptr_type_node);
812 /* Otherwise make a new alias set for this type. */
813 else
815 /* Each canonical type gets its own alias set, so canonical types
816 shouldn't form a tree. It doesn't really matter for types
817 we handle specially above, so only check it where it possibly
818 would result in a bogus alias set. */
819 gcc_checking_assert (TYPE_CANONICAL (t) == t);
821 set = new_alias_set ();
824 TYPE_ALIAS_SET (t) = set;
826 /* If this is an aggregate type or a complex type, we must record any
827 component aliasing information. */
828 if (AGGREGATE_TYPE_P (t) || TREE_CODE (t) == COMPLEX_TYPE)
829 record_component_aliases (t);
831 return set;
834 /* Return a brand-new alias set. */
836 alias_set_type
837 new_alias_set (void)
839 if (flag_strict_aliasing)
841 if (alias_sets == 0)
842 VEC_safe_push (alias_set_entry, gc, alias_sets, 0);
843 VEC_safe_push (alias_set_entry, gc, alias_sets, 0);
844 return VEC_length (alias_set_entry, alias_sets) - 1;
846 else
847 return 0;
850 /* Indicate that things in SUBSET can alias things in SUPERSET, but that
851 not everything that aliases SUPERSET also aliases SUBSET. For example,
852 in C, a store to an `int' can alias a load of a structure containing an
853 `int', and vice versa. But it can't alias a load of a 'double' member
854 of the same structure. Here, the structure would be the SUPERSET and
855 `int' the SUBSET. This relationship is also described in the comment at
856 the beginning of this file.
858 This function should be called only once per SUPERSET/SUBSET pair.
860 It is illegal for SUPERSET to be zero; everything is implicitly a
861 subset of alias set zero. */
863 void
864 record_alias_subset (alias_set_type superset, alias_set_type subset)
866 alias_set_entry superset_entry;
867 alias_set_entry subset_entry;
869 /* It is possible in complex type situations for both sets to be the same,
870 in which case we can ignore this operation. */
871 if (superset == subset)
872 return;
874 gcc_assert (superset);
876 superset_entry = get_alias_set_entry (superset);
877 if (superset_entry == 0)
879 /* Create an entry for the SUPERSET, so that we have a place to
880 attach the SUBSET. */
881 superset_entry = ggc_alloc_cleared_alias_set_entry_d ();
882 superset_entry->alias_set = superset;
883 superset_entry->children
884 = splay_tree_new_ggc (splay_tree_compare_ints,
885 ggc_alloc_splay_tree_scalar_scalar_splay_tree_s,
886 ggc_alloc_splay_tree_scalar_scalar_splay_tree_node_s);
887 superset_entry->has_zero_child = 0;
888 VEC_replace (alias_set_entry, alias_sets, superset, superset_entry);
891 if (subset == 0)
892 superset_entry->has_zero_child = 1;
893 else
895 subset_entry = get_alias_set_entry (subset);
896 /* If there is an entry for the subset, enter all of its children
897 (if they are not already present) as children of the SUPERSET. */
898 if (subset_entry)
900 if (subset_entry->has_zero_child)
901 superset_entry->has_zero_child = 1;
903 splay_tree_foreach (subset_entry->children, insert_subset_children,
904 superset_entry->children);
907 /* Enter the SUBSET itself as a child of the SUPERSET. */
908 splay_tree_insert (superset_entry->children,
909 (splay_tree_key) subset, 0);
913 /* Record that component types of TYPE, if any, are part of that type for
914 aliasing purposes. For record types, we only record component types
915 for fields that are not marked non-addressable. For array types, we
916 only record the component type if it is not marked non-aliased. */
918 void
919 record_component_aliases (tree type)
921 alias_set_type superset = get_alias_set (type);
922 tree field;
924 if (superset == 0)
925 return;
927 switch (TREE_CODE (type))
929 case RECORD_TYPE:
930 case UNION_TYPE:
931 case QUAL_UNION_TYPE:
932 /* Recursively record aliases for the base classes, if there are any. */
933 if (TYPE_BINFO (type))
935 int i;
936 tree binfo, base_binfo;
938 for (binfo = TYPE_BINFO (type), i = 0;
939 BINFO_BASE_ITERATE (binfo, i, base_binfo); i++)
940 record_alias_subset (superset,
941 get_alias_set (BINFO_TYPE (base_binfo)));
943 for (field = TYPE_FIELDS (type); field != 0; field = DECL_CHAIN (field))
944 if (TREE_CODE (field) == FIELD_DECL && !DECL_NONADDRESSABLE_P (field))
945 record_alias_subset (superset, get_alias_set (TREE_TYPE (field)));
946 break;
948 case COMPLEX_TYPE:
949 record_alias_subset (superset, get_alias_set (TREE_TYPE (type)));
950 break;
952 /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their
953 element type. */
955 default:
956 break;
960 /* Allocate an alias set for use in storing and reading from the varargs
961 spill area. */
963 static GTY(()) alias_set_type varargs_set = -1;
965 alias_set_type
966 get_varargs_alias_set (void)
968 #if 1
969 /* We now lower VA_ARG_EXPR, and there's currently no way to attach the
970 varargs alias set to an INDIRECT_REF (FIXME!), so we can't
971 consistently use the varargs alias set for loads from the varargs
972 area. So don't use it anywhere. */
973 return 0;
974 #else
975 if (varargs_set == -1)
976 varargs_set = new_alias_set ();
978 return varargs_set;
979 #endif
982 /* Likewise, but used for the fixed portions of the frame, e.g., register
983 save areas. */
985 static GTY(()) alias_set_type frame_set = -1;
987 alias_set_type
988 get_frame_alias_set (void)
990 if (frame_set == -1)
991 frame_set = new_alias_set ();
993 return frame_set;
996 /* Inside SRC, the source of a SET, find a base address. */
998 static rtx
999 find_base_value (rtx src)
1001 unsigned int regno;
1003 #if defined (FIND_BASE_TERM)
1004 /* Try machine-dependent ways to find the base term. */
1005 src = FIND_BASE_TERM (src);
1006 #endif
1008 switch (GET_CODE (src))
1010 case SYMBOL_REF:
1011 case LABEL_REF:
1012 return src;
1014 case REG:
1015 regno = REGNO (src);
1016 /* At the start of a function, argument registers have known base
1017 values which may be lost later. Returning an ADDRESS
1018 expression here allows optimization based on argument values
1019 even when the argument registers are used for other purposes. */
1020 if (regno < FIRST_PSEUDO_REGISTER && copying_arguments)
1021 return new_reg_base_value[regno];
1023 /* If a pseudo has a known base value, return it. Do not do this
1024 for non-fixed hard regs since it can result in a circular
1025 dependency chain for registers which have values at function entry.
1027 The test above is not sufficient because the scheduler may move
1028 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
1029 if ((regno >= FIRST_PSEUDO_REGISTER || fixed_regs[regno])
1030 && regno < VEC_length (rtx, reg_base_value))
1032 /* If we're inside init_alias_analysis, use new_reg_base_value
1033 to reduce the number of relaxation iterations. */
1034 if (new_reg_base_value && new_reg_base_value[regno]
1035 && DF_REG_DEF_COUNT (regno) == 1)
1036 return new_reg_base_value[regno];
1038 if (VEC_index (rtx, reg_base_value, regno))
1039 return VEC_index (rtx, reg_base_value, regno);
1042 return 0;
1044 case MEM:
1045 /* Check for an argument passed in memory. Only record in the
1046 copying-arguments block; it is too hard to track changes
1047 otherwise. */
1048 if (copying_arguments
1049 && (XEXP (src, 0) == arg_pointer_rtx
1050 || (GET_CODE (XEXP (src, 0)) == PLUS
1051 && XEXP (XEXP (src, 0), 0) == arg_pointer_rtx)))
1052 return gen_rtx_ADDRESS (VOIDmode, src);
1053 return 0;
1055 case CONST:
1056 src = XEXP (src, 0);
1057 if (GET_CODE (src) != PLUS && GET_CODE (src) != MINUS)
1058 break;
1060 /* ... fall through ... */
1062 case PLUS:
1063 case MINUS:
1065 rtx temp, src_0 = XEXP (src, 0), src_1 = XEXP (src, 1);
1067 /* If either operand is a REG that is a known pointer, then it
1068 is the base. */
1069 if (REG_P (src_0) && REG_POINTER (src_0))
1070 return find_base_value (src_0);
1071 if (REG_P (src_1) && REG_POINTER (src_1))
1072 return find_base_value (src_1);
1074 /* If either operand is a REG, then see if we already have
1075 a known value for it. */
1076 if (REG_P (src_0))
1078 temp = find_base_value (src_0);
1079 if (temp != 0)
1080 src_0 = temp;
1083 if (REG_P (src_1))
1085 temp = find_base_value (src_1);
1086 if (temp!= 0)
1087 src_1 = temp;
1090 /* If either base is named object or a special address
1091 (like an argument or stack reference), then use it for the
1092 base term. */
1093 if (src_0 != 0
1094 && (GET_CODE (src_0) == SYMBOL_REF
1095 || GET_CODE (src_0) == LABEL_REF
1096 || (GET_CODE (src_0) == ADDRESS
1097 && GET_MODE (src_0) != VOIDmode)))
1098 return src_0;
1100 if (src_1 != 0
1101 && (GET_CODE (src_1) == SYMBOL_REF
1102 || GET_CODE (src_1) == LABEL_REF
1103 || (GET_CODE (src_1) == ADDRESS
1104 && GET_MODE (src_1) != VOIDmode)))
1105 return src_1;
1107 /* Guess which operand is the base address:
1108 If either operand is a symbol, then it is the base. If
1109 either operand is a CONST_INT, then the other is the base. */
1110 if (CONST_INT_P (src_1) || CONSTANT_P (src_0))
1111 return find_base_value (src_0);
1112 else if (CONST_INT_P (src_0) || CONSTANT_P (src_1))
1113 return find_base_value (src_1);
1115 return 0;
1118 case LO_SUM:
1119 /* The standard form is (lo_sum reg sym) so look only at the
1120 second operand. */
1121 return find_base_value (XEXP (src, 1));
1123 case AND:
1124 /* If the second operand is constant set the base
1125 address to the first operand. */
1126 if (CONST_INT_P (XEXP (src, 1)) && INTVAL (XEXP (src, 1)) != 0)
1127 return find_base_value (XEXP (src, 0));
1128 return 0;
1130 case TRUNCATE:
1131 /* As we do not know which address space the pointer is refering to, we can
1132 handle this only if the target does not support different pointer or
1133 address modes depending on the address space. */
1134 if (!target_default_pointer_address_modes_p ())
1135 break;
1136 if (GET_MODE_SIZE (GET_MODE (src)) < GET_MODE_SIZE (Pmode))
1137 break;
1138 /* Fall through. */
1139 case HIGH:
1140 case PRE_INC:
1141 case PRE_DEC:
1142 case POST_INC:
1143 case POST_DEC:
1144 case PRE_MODIFY:
1145 case POST_MODIFY:
1146 return find_base_value (XEXP (src, 0));
1148 case ZERO_EXTEND:
1149 case SIGN_EXTEND: /* used for NT/Alpha pointers */
1150 /* As we do not know which address space the pointer is refering to, we can
1151 handle this only if the target does not support different pointer or
1152 address modes depending on the address space. */
1153 if (!target_default_pointer_address_modes_p ())
1154 break;
1157 rtx temp = find_base_value (XEXP (src, 0));
1159 if (temp != 0 && CONSTANT_P (temp))
1160 temp = convert_memory_address (Pmode, temp);
1162 return temp;
1165 default:
1166 break;
1169 return 0;
1172 /* Called from init_alias_analysis indirectly through note_stores. */
1174 /* While scanning insns to find base values, reg_seen[N] is nonzero if
1175 register N has been set in this function. */
1176 static char *reg_seen;
1178 /* Addresses which are known not to alias anything else are identified
1179 by a unique integer. */
1180 static int unique_id;
1182 static void
1183 record_set (rtx dest, const_rtx set, void *data ATTRIBUTE_UNUSED)
1185 unsigned regno;
1186 rtx src;
1187 int n;
1189 if (!REG_P (dest))
1190 return;
1192 regno = REGNO (dest);
1194 gcc_checking_assert (regno < VEC_length (rtx, reg_base_value));
1196 /* If this spans multiple hard registers, then we must indicate that every
1197 register has an unusable value. */
1198 if (regno < FIRST_PSEUDO_REGISTER)
1199 n = hard_regno_nregs[regno][GET_MODE (dest)];
1200 else
1201 n = 1;
1202 if (n != 1)
1204 while (--n >= 0)
1206 reg_seen[regno + n] = 1;
1207 new_reg_base_value[regno + n] = 0;
1209 return;
1212 if (set)
1214 /* A CLOBBER wipes out any old value but does not prevent a previously
1215 unset register from acquiring a base address (i.e. reg_seen is not
1216 set). */
1217 if (GET_CODE (set) == CLOBBER)
1219 new_reg_base_value[regno] = 0;
1220 return;
1222 src = SET_SRC (set);
1224 else
1226 if (reg_seen[regno])
1228 new_reg_base_value[regno] = 0;
1229 return;
1231 reg_seen[regno] = 1;
1232 new_reg_base_value[regno] = gen_rtx_ADDRESS (Pmode,
1233 GEN_INT (unique_id++));
1234 return;
1237 /* If this is not the first set of REGNO, see whether the new value
1238 is related to the old one. There are two cases of interest:
1240 (1) The register might be assigned an entirely new value
1241 that has the same base term as the original set.
1243 (2) The set might be a simple self-modification that
1244 cannot change REGNO's base value.
1246 If neither case holds, reject the original base value as invalid.
1247 Note that the following situation is not detected:
1249 extern int x, y; int *p = &x; p += (&y-&x);
1251 ANSI C does not allow computing the difference of addresses
1252 of distinct top level objects. */
1253 if (new_reg_base_value[regno] != 0
1254 && find_base_value (src) != new_reg_base_value[regno])
1255 switch (GET_CODE (src))
1257 case LO_SUM:
1258 case MINUS:
1259 if (XEXP (src, 0) != dest && XEXP (src, 1) != dest)
1260 new_reg_base_value[regno] = 0;
1261 break;
1262 case PLUS:
1263 /* If the value we add in the PLUS is also a valid base value,
1264 this might be the actual base value, and the original value
1265 an index. */
1267 rtx other = NULL_RTX;
1269 if (XEXP (src, 0) == dest)
1270 other = XEXP (src, 1);
1271 else if (XEXP (src, 1) == dest)
1272 other = XEXP (src, 0);
1274 if (! other || find_base_value (other))
1275 new_reg_base_value[regno] = 0;
1276 break;
1278 case AND:
1279 if (XEXP (src, 0) != dest || !CONST_INT_P (XEXP (src, 1)))
1280 new_reg_base_value[regno] = 0;
1281 break;
1282 default:
1283 new_reg_base_value[regno] = 0;
1284 break;
1286 /* If this is the first set of a register, record the value. */
1287 else if ((regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
1288 && ! reg_seen[regno] && new_reg_base_value[regno] == 0)
1289 new_reg_base_value[regno] = find_base_value (src);
1291 reg_seen[regno] = 1;
1294 /* Return REG_BASE_VALUE for REGNO. Selective scheduler uses this to avoid
1295 using hard registers with non-null REG_BASE_VALUE for renaming. */
1297 get_reg_base_value (unsigned int regno)
1299 return VEC_index (rtx, reg_base_value, regno);
1302 /* If a value is known for REGNO, return it. */
1305 get_reg_known_value (unsigned int regno)
1307 if (regno >= FIRST_PSEUDO_REGISTER)
1309 regno -= FIRST_PSEUDO_REGISTER;
1310 if (regno < reg_known_value_size)
1311 return reg_known_value[regno];
1313 return NULL;
1316 /* Set it. */
1318 static void
1319 set_reg_known_value (unsigned int regno, rtx val)
1321 if (regno >= FIRST_PSEUDO_REGISTER)
1323 regno -= FIRST_PSEUDO_REGISTER;
1324 if (regno < reg_known_value_size)
1325 reg_known_value[regno] = val;
1329 /* Similarly for reg_known_equiv_p. */
1331 bool
1332 get_reg_known_equiv_p (unsigned int regno)
1334 if (regno >= FIRST_PSEUDO_REGISTER)
1336 regno -= FIRST_PSEUDO_REGISTER;
1337 if (regno < reg_known_value_size)
1338 return reg_known_equiv_p[regno];
1340 return false;
1343 static void
1344 set_reg_known_equiv_p (unsigned int regno, bool val)
1346 if (regno >= FIRST_PSEUDO_REGISTER)
1348 regno -= FIRST_PSEUDO_REGISTER;
1349 if (regno < reg_known_value_size)
1350 reg_known_equiv_p[regno] = val;
1355 /* Returns a canonical version of X, from the point of view alias
1356 analysis. (For example, if X is a MEM whose address is a register,
1357 and the register has a known value (say a SYMBOL_REF), then a MEM
1358 whose address is the SYMBOL_REF is returned.) */
1361 canon_rtx (rtx x)
1363 /* Recursively look for equivalences. */
1364 if (REG_P (x) && REGNO (x) >= FIRST_PSEUDO_REGISTER)
1366 rtx t = get_reg_known_value (REGNO (x));
1367 if (t == x)
1368 return x;
1369 if (t)
1370 return canon_rtx (t);
1373 if (GET_CODE (x) == PLUS)
1375 rtx x0 = canon_rtx (XEXP (x, 0));
1376 rtx x1 = canon_rtx (XEXP (x, 1));
1378 if (x0 != XEXP (x, 0) || x1 != XEXP (x, 1))
1380 if (CONST_INT_P (x0))
1381 return plus_constant (x1, INTVAL (x0));
1382 else if (CONST_INT_P (x1))
1383 return plus_constant (x0, INTVAL (x1));
1384 return gen_rtx_PLUS (GET_MODE (x), x0, x1);
1388 /* This gives us much better alias analysis when called from
1389 the loop optimizer. Note we want to leave the original
1390 MEM alone, but need to return the canonicalized MEM with
1391 all the flags with their original values. */
1392 else if (MEM_P (x))
1393 x = replace_equiv_address_nv (x, canon_rtx (XEXP (x, 0)));
1395 return x;
1398 /* Return 1 if X and Y are identical-looking rtx's.
1399 Expect that X and Y has been already canonicalized.
1401 We use the data in reg_known_value above to see if two registers with
1402 different numbers are, in fact, equivalent. */
1404 static int
1405 rtx_equal_for_memref_p (const_rtx x, const_rtx y)
1407 int i;
1408 int j;
1409 enum rtx_code code;
1410 const char *fmt;
1412 if (x == 0 && y == 0)
1413 return 1;
1414 if (x == 0 || y == 0)
1415 return 0;
1417 if (x == y)
1418 return 1;
1420 code = GET_CODE (x);
1421 /* Rtx's of different codes cannot be equal. */
1422 if (code != GET_CODE (y))
1423 return 0;
1425 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1426 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1428 if (GET_MODE (x) != GET_MODE (y))
1429 return 0;
1431 /* Some RTL can be compared without a recursive examination. */
1432 switch (code)
1434 case REG:
1435 return REGNO (x) == REGNO (y);
1437 case LABEL_REF:
1438 return XEXP (x, 0) == XEXP (y, 0);
1440 case SYMBOL_REF:
1441 return XSTR (x, 0) == XSTR (y, 0);
1443 case VALUE:
1444 case CONST_INT:
1445 case CONST_DOUBLE:
1446 case CONST_FIXED:
1447 /* There's no need to compare the contents of CONST_DOUBLEs or
1448 CONST_INTs because pointer equality is a good enough
1449 comparison for these nodes. */
1450 return 0;
1452 default:
1453 break;
1456 /* canon_rtx knows how to handle plus. No need to canonicalize. */
1457 if (code == PLUS)
1458 return ((rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0))
1459 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1)))
1460 || (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 1))
1461 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 0))));
1462 /* For commutative operations, the RTX match if the operand match in any
1463 order. Also handle the simple binary and unary cases without a loop. */
1464 if (COMMUTATIVE_P (x))
1466 rtx xop0 = canon_rtx (XEXP (x, 0));
1467 rtx yop0 = canon_rtx (XEXP (y, 0));
1468 rtx yop1 = canon_rtx (XEXP (y, 1));
1470 return ((rtx_equal_for_memref_p (xop0, yop0)
1471 && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)), yop1))
1472 || (rtx_equal_for_memref_p (xop0, yop1)
1473 && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)), yop0)));
1475 else if (NON_COMMUTATIVE_P (x))
1477 return (rtx_equal_for_memref_p (canon_rtx (XEXP (x, 0)),
1478 canon_rtx (XEXP (y, 0)))
1479 && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)),
1480 canon_rtx (XEXP (y, 1))));
1482 else if (UNARY_P (x))
1483 return rtx_equal_for_memref_p (canon_rtx (XEXP (x, 0)),
1484 canon_rtx (XEXP (y, 0)));
1486 /* Compare the elements. If any pair of corresponding elements
1487 fail to match, return 0 for the whole things.
1489 Limit cases to types which actually appear in addresses. */
1491 fmt = GET_RTX_FORMAT (code);
1492 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1494 switch (fmt[i])
1496 case 'i':
1497 if (XINT (x, i) != XINT (y, i))
1498 return 0;
1499 break;
1501 case 'E':
1502 /* Two vectors must have the same length. */
1503 if (XVECLEN (x, i) != XVECLEN (y, i))
1504 return 0;
1506 /* And the corresponding elements must match. */
1507 for (j = 0; j < XVECLEN (x, i); j++)
1508 if (rtx_equal_for_memref_p (canon_rtx (XVECEXP (x, i, j)),
1509 canon_rtx (XVECEXP (y, i, j))) == 0)
1510 return 0;
1511 break;
1513 case 'e':
1514 if (rtx_equal_for_memref_p (canon_rtx (XEXP (x, i)),
1515 canon_rtx (XEXP (y, i))) == 0)
1516 return 0;
1517 break;
1519 /* This can happen for asm operands. */
1520 case 's':
1521 if (strcmp (XSTR (x, i), XSTR (y, i)))
1522 return 0;
1523 break;
1525 /* This can happen for an asm which clobbers memory. */
1526 case '0':
1527 break;
1529 /* It is believed that rtx's at this level will never
1530 contain anything but integers and other rtx's,
1531 except for within LABEL_REFs and SYMBOL_REFs. */
1532 default:
1533 gcc_unreachable ();
1536 return 1;
1540 find_base_term (rtx x)
1542 cselib_val *val;
1543 struct elt_loc_list *l, *f;
1544 rtx ret;
1546 #if defined (FIND_BASE_TERM)
1547 /* Try machine-dependent ways to find the base term. */
1548 x = FIND_BASE_TERM (x);
1549 #endif
1551 switch (GET_CODE (x))
1553 case REG:
1554 return REG_BASE_VALUE (x);
1556 case TRUNCATE:
1557 /* As we do not know which address space the pointer is refering to, we can
1558 handle this only if the target does not support different pointer or
1559 address modes depending on the address space. */
1560 if (!target_default_pointer_address_modes_p ())
1561 return 0;
1562 if (GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (Pmode))
1563 return 0;
1564 /* Fall through. */
1565 case HIGH:
1566 case PRE_INC:
1567 case PRE_DEC:
1568 case POST_INC:
1569 case POST_DEC:
1570 case PRE_MODIFY:
1571 case POST_MODIFY:
1572 return find_base_term (XEXP (x, 0));
1574 case ZERO_EXTEND:
1575 case SIGN_EXTEND: /* Used for Alpha/NT pointers */
1576 /* As we do not know which address space the pointer is refering to, we can
1577 handle this only if the target does not support different pointer or
1578 address modes depending on the address space. */
1579 if (!target_default_pointer_address_modes_p ())
1580 return 0;
1583 rtx temp = find_base_term (XEXP (x, 0));
1585 if (temp != 0 && CONSTANT_P (temp))
1586 temp = convert_memory_address (Pmode, temp);
1588 return temp;
1591 case VALUE:
1592 val = CSELIB_VAL_PTR (x);
1593 ret = NULL_RTX;
1595 if (!val)
1596 return ret;
1598 f = val->locs;
1599 /* Temporarily reset val->locs to avoid infinite recursion. */
1600 val->locs = NULL;
1602 for (l = f; l; l = l->next)
1603 if (GET_CODE (l->loc) == VALUE
1604 && CSELIB_VAL_PTR (l->loc)->locs
1605 && !CSELIB_VAL_PTR (l->loc)->locs->next
1606 && CSELIB_VAL_PTR (l->loc)->locs->loc == x)
1607 continue;
1608 else if ((ret = find_base_term (l->loc)) != 0)
1609 break;
1611 val->locs = f;
1612 return ret;
1614 case LO_SUM:
1615 /* The standard form is (lo_sum reg sym) so look only at the
1616 second operand. */
1617 return find_base_term (XEXP (x, 1));
1619 case CONST:
1620 x = XEXP (x, 0);
1621 if (GET_CODE (x) != PLUS && GET_CODE (x) != MINUS)
1622 return 0;
1623 /* Fall through. */
1624 case PLUS:
1625 case MINUS:
1627 rtx tmp1 = XEXP (x, 0);
1628 rtx tmp2 = XEXP (x, 1);
1630 /* This is a little bit tricky since we have to determine which of
1631 the two operands represents the real base address. Otherwise this
1632 routine may return the index register instead of the base register.
1634 That may cause us to believe no aliasing was possible, when in
1635 fact aliasing is possible.
1637 We use a few simple tests to guess the base register. Additional
1638 tests can certainly be added. For example, if one of the operands
1639 is a shift or multiply, then it must be the index register and the
1640 other operand is the base register. */
1642 if (tmp1 == pic_offset_table_rtx && CONSTANT_P (tmp2))
1643 return find_base_term (tmp2);
1645 /* If either operand is known to be a pointer, then use it
1646 to determine the base term. */
1647 if (REG_P (tmp1) && REG_POINTER (tmp1))
1649 rtx base = find_base_term (tmp1);
1650 if (base)
1651 return base;
1654 if (REG_P (tmp2) && REG_POINTER (tmp2))
1656 rtx base = find_base_term (tmp2);
1657 if (base)
1658 return base;
1661 /* Neither operand was known to be a pointer. Go ahead and find the
1662 base term for both operands. */
1663 tmp1 = find_base_term (tmp1);
1664 tmp2 = find_base_term (tmp2);
1666 /* If either base term is named object or a special address
1667 (like an argument or stack reference), then use it for the
1668 base term. */
1669 if (tmp1 != 0
1670 && (GET_CODE (tmp1) == SYMBOL_REF
1671 || GET_CODE (tmp1) == LABEL_REF
1672 || (GET_CODE (tmp1) == ADDRESS
1673 && GET_MODE (tmp1) != VOIDmode)))
1674 return tmp1;
1676 if (tmp2 != 0
1677 && (GET_CODE (tmp2) == SYMBOL_REF
1678 || GET_CODE (tmp2) == LABEL_REF
1679 || (GET_CODE (tmp2) == ADDRESS
1680 && GET_MODE (tmp2) != VOIDmode)))
1681 return tmp2;
1683 /* We could not determine which of the two operands was the
1684 base register and which was the index. So we can determine
1685 nothing from the base alias check. */
1686 return 0;
1689 case AND:
1690 if (CONST_INT_P (XEXP (x, 1)) && INTVAL (XEXP (x, 1)) != 0)
1691 return find_base_term (XEXP (x, 0));
1692 return 0;
1694 case SYMBOL_REF:
1695 case LABEL_REF:
1696 return x;
1698 default:
1699 return 0;
1703 /* Return 0 if the addresses X and Y are known to point to different
1704 objects, 1 if they might be pointers to the same object. */
1706 static int
1707 base_alias_check (rtx x, rtx y, enum machine_mode x_mode,
1708 enum machine_mode y_mode)
1710 rtx x_base = find_base_term (x);
1711 rtx y_base = find_base_term (y);
1713 /* If the address itself has no known base see if a known equivalent
1714 value has one. If either address still has no known base, nothing
1715 is known about aliasing. */
1716 if (x_base == 0)
1718 rtx x_c;
1720 if (! flag_expensive_optimizations || (x_c = canon_rtx (x)) == x)
1721 return 1;
1723 x_base = find_base_term (x_c);
1724 if (x_base == 0)
1725 return 1;
1728 if (y_base == 0)
1730 rtx y_c;
1731 if (! flag_expensive_optimizations || (y_c = canon_rtx (y)) == y)
1732 return 1;
1734 y_base = find_base_term (y_c);
1735 if (y_base == 0)
1736 return 1;
1739 /* If the base addresses are equal nothing is known about aliasing. */
1740 if (rtx_equal_p (x_base, y_base))
1741 return 1;
1743 /* The base addresses are different expressions. If they are not accessed
1744 via AND, there is no conflict. We can bring knowledge of object
1745 alignment into play here. For example, on alpha, "char a, b;" can
1746 alias one another, though "char a; long b;" cannot. AND addesses may
1747 implicitly alias surrounding objects; i.e. unaligned access in DImode
1748 via AND address can alias all surrounding object types except those
1749 with aligment 8 or higher. */
1750 if (GET_CODE (x) == AND && GET_CODE (y) == AND)
1751 return 1;
1752 if (GET_CODE (x) == AND
1753 && (!CONST_INT_P (XEXP (x, 1))
1754 || (int) GET_MODE_UNIT_SIZE (y_mode) < -INTVAL (XEXP (x, 1))))
1755 return 1;
1756 if (GET_CODE (y) == AND
1757 && (!CONST_INT_P (XEXP (y, 1))
1758 || (int) GET_MODE_UNIT_SIZE (x_mode) < -INTVAL (XEXP (y, 1))))
1759 return 1;
1761 /* Differing symbols not accessed via AND never alias. */
1762 if (GET_CODE (x_base) != ADDRESS && GET_CODE (y_base) != ADDRESS)
1763 return 0;
1765 /* If one address is a stack reference there can be no alias:
1766 stack references using different base registers do not alias,
1767 a stack reference can not alias a parameter, and a stack reference
1768 can not alias a global. */
1769 if ((GET_CODE (x_base) == ADDRESS && GET_MODE (x_base) == Pmode)
1770 || (GET_CODE (y_base) == ADDRESS && GET_MODE (y_base) == Pmode))
1771 return 0;
1773 return 1;
1776 /* Callback for for_each_rtx, that returns 1 upon encountering a VALUE
1777 whose UID is greater than the int uid that D points to. */
1779 static int
1780 refs_newer_value_cb (rtx *x, void *d)
1782 if (GET_CODE (*x) == VALUE && CSELIB_VAL_PTR (*x)->uid > *(int *)d)
1783 return 1;
1785 return 0;
1788 /* Return TRUE if EXPR refers to a VALUE whose uid is greater than
1789 that of V. */
1791 static bool
1792 refs_newer_value_p (rtx expr, rtx v)
1794 int minuid = CSELIB_VAL_PTR (v)->uid;
1796 return for_each_rtx (&expr, refs_newer_value_cb, &minuid);
1799 /* Convert the address X into something we can use. This is done by returning
1800 it unchanged unless it is a value; in the latter case we call cselib to get
1801 a more useful rtx. */
1804 get_addr (rtx x)
1806 cselib_val *v;
1807 struct elt_loc_list *l;
1809 if (GET_CODE (x) != VALUE)
1810 return x;
1811 v = CSELIB_VAL_PTR (x);
1812 if (v)
1814 bool have_equivs = cselib_have_permanent_equivalences ();
1815 if (have_equivs)
1816 v = canonical_cselib_val (v);
1817 for (l = v->locs; l; l = l->next)
1818 if (CONSTANT_P (l->loc))
1819 return l->loc;
1820 for (l = v->locs; l; l = l->next)
1821 if (!REG_P (l->loc) && !MEM_P (l->loc)
1822 /* Avoid infinite recursion when potentially dealing with
1823 var-tracking artificial equivalences, by skipping the
1824 equivalences themselves, and not choosing expressions
1825 that refer to newer VALUEs. */
1826 && (!have_equivs
1827 || (GET_CODE (l->loc) != VALUE
1828 && !refs_newer_value_p (l->loc, x))))
1829 return l->loc;
1830 if (have_equivs)
1832 for (l = v->locs; l; l = l->next)
1833 if (REG_P (l->loc)
1834 || (GET_CODE (l->loc) != VALUE
1835 && !refs_newer_value_p (l->loc, x)))
1836 return l->loc;
1837 /* Return the canonical value. */
1838 return v->val_rtx;
1840 if (v->locs)
1841 return v->locs->loc;
1843 return x;
1846 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
1847 where SIZE is the size in bytes of the memory reference. If ADDR
1848 is not modified by the memory reference then ADDR is returned. */
1850 static rtx
1851 addr_side_effect_eval (rtx addr, int size, int n_refs)
1853 int offset = 0;
1855 switch (GET_CODE (addr))
1857 case PRE_INC:
1858 offset = (n_refs + 1) * size;
1859 break;
1860 case PRE_DEC:
1861 offset = -(n_refs + 1) * size;
1862 break;
1863 case POST_INC:
1864 offset = n_refs * size;
1865 break;
1866 case POST_DEC:
1867 offset = -n_refs * size;
1868 break;
1870 default:
1871 return addr;
1874 if (offset)
1875 addr = gen_rtx_PLUS (GET_MODE (addr), XEXP (addr, 0),
1876 GEN_INT (offset));
1877 else
1878 addr = XEXP (addr, 0);
1879 addr = canon_rtx (addr);
1881 return addr;
1884 /* Return one if X and Y (memory addresses) reference the
1885 same location in memory or if the references overlap.
1886 Return zero if they do not overlap, else return
1887 minus one in which case they still might reference the same location.
1889 C is an offset accumulator. When
1890 C is nonzero, we are testing aliases between X and Y + C.
1891 XSIZE is the size in bytes of the X reference,
1892 similarly YSIZE is the size in bytes for Y.
1893 Expect that canon_rtx has been already called for X and Y.
1895 If XSIZE or YSIZE is zero, we do not know the amount of memory being
1896 referenced (the reference was BLKmode), so make the most pessimistic
1897 assumptions.
1899 If XSIZE or YSIZE is negative, we may access memory outside the object
1900 being referenced as a side effect. This can happen when using AND to
1901 align memory references, as is done on the Alpha.
1903 Nice to notice that varying addresses cannot conflict with fp if no
1904 local variables had their addresses taken, but that's too hard now.
1906 ??? Contrary to the tree alias oracle this does not return
1907 one for X + non-constant and Y + non-constant when X and Y are equal.
1908 If that is fixed the TBAA hack for union type-punning can be removed. */
1910 static int
1911 memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c)
1913 if (GET_CODE (x) == VALUE)
1915 if (REG_P (y))
1917 struct elt_loc_list *l = NULL;
1918 if (CSELIB_VAL_PTR (x))
1919 for (l = canonical_cselib_val (CSELIB_VAL_PTR (x))->locs;
1920 l; l = l->next)
1921 if (REG_P (l->loc) && rtx_equal_for_memref_p (l->loc, y))
1922 break;
1923 if (l)
1924 x = y;
1925 else
1926 x = get_addr (x);
1928 /* Don't call get_addr if y is the same VALUE. */
1929 else if (x != y)
1930 x = get_addr (x);
1932 if (GET_CODE (y) == VALUE)
1934 if (REG_P (x))
1936 struct elt_loc_list *l = NULL;
1937 if (CSELIB_VAL_PTR (y))
1938 for (l = canonical_cselib_val (CSELIB_VAL_PTR (y))->locs;
1939 l; l = l->next)
1940 if (REG_P (l->loc) && rtx_equal_for_memref_p (l->loc, x))
1941 break;
1942 if (l)
1943 y = x;
1944 else
1945 y = get_addr (y);
1947 /* Don't call get_addr if x is the same VALUE. */
1948 else if (y != x)
1949 y = get_addr (y);
1951 if (GET_CODE (x) == HIGH)
1952 x = XEXP (x, 0);
1953 else if (GET_CODE (x) == LO_SUM)
1954 x = XEXP (x, 1);
1955 else
1956 x = addr_side_effect_eval (x, xsize, 0);
1957 if (GET_CODE (y) == HIGH)
1958 y = XEXP (y, 0);
1959 else if (GET_CODE (y) == LO_SUM)
1960 y = XEXP (y, 1);
1961 else
1962 y = addr_side_effect_eval (y, ysize, 0);
1964 if (rtx_equal_for_memref_p (x, y))
1966 if (xsize <= 0 || ysize <= 0)
1967 return 1;
1968 if (c >= 0 && xsize > c)
1969 return 1;
1970 if (c < 0 && ysize+c > 0)
1971 return 1;
1972 return 0;
1975 /* This code used to check for conflicts involving stack references and
1976 globals but the base address alias code now handles these cases. */
1978 if (GET_CODE (x) == PLUS)
1980 /* The fact that X is canonicalized means that this
1981 PLUS rtx is canonicalized. */
1982 rtx x0 = XEXP (x, 0);
1983 rtx x1 = XEXP (x, 1);
1985 if (GET_CODE (y) == PLUS)
1987 /* The fact that Y is canonicalized means that this
1988 PLUS rtx is canonicalized. */
1989 rtx y0 = XEXP (y, 0);
1990 rtx y1 = XEXP (y, 1);
1992 if (rtx_equal_for_memref_p (x1, y1))
1993 return memrefs_conflict_p (xsize, x0, ysize, y0, c);
1994 if (rtx_equal_for_memref_p (x0, y0))
1995 return memrefs_conflict_p (xsize, x1, ysize, y1, c);
1996 if (CONST_INT_P (x1))
1998 if (CONST_INT_P (y1))
1999 return memrefs_conflict_p (xsize, x0, ysize, y0,
2000 c - INTVAL (x1) + INTVAL (y1));
2001 else
2002 return memrefs_conflict_p (xsize, x0, ysize, y,
2003 c - INTVAL (x1));
2005 else if (CONST_INT_P (y1))
2006 return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
2008 return -1;
2010 else if (CONST_INT_P (x1))
2011 return memrefs_conflict_p (xsize, x0, ysize, y, c - INTVAL (x1));
2013 else if (GET_CODE (y) == PLUS)
2015 /* The fact that Y is canonicalized means that this
2016 PLUS rtx is canonicalized. */
2017 rtx y0 = XEXP (y, 0);
2018 rtx y1 = XEXP (y, 1);
2020 if (CONST_INT_P (y1))
2021 return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
2022 else
2023 return -1;
2026 if (GET_CODE (x) == GET_CODE (y))
2027 switch (GET_CODE (x))
2029 case MULT:
2031 /* Handle cases where we expect the second operands to be the
2032 same, and check only whether the first operand would conflict
2033 or not. */
2034 rtx x0, y0;
2035 rtx x1 = canon_rtx (XEXP (x, 1));
2036 rtx y1 = canon_rtx (XEXP (y, 1));
2037 if (! rtx_equal_for_memref_p (x1, y1))
2038 return -1;
2039 x0 = canon_rtx (XEXP (x, 0));
2040 y0 = canon_rtx (XEXP (y, 0));
2041 if (rtx_equal_for_memref_p (x0, y0))
2042 return (xsize == 0 || ysize == 0
2043 || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
2045 /* Can't properly adjust our sizes. */
2046 if (!CONST_INT_P (x1))
2047 return -1;
2048 xsize /= INTVAL (x1);
2049 ysize /= INTVAL (x1);
2050 c /= INTVAL (x1);
2051 return memrefs_conflict_p (xsize, x0, ysize, y0, c);
2054 default:
2055 break;
2058 /* Treat an access through an AND (e.g. a subword access on an Alpha)
2059 as an access with indeterminate size. Assume that references
2060 besides AND are aligned, so if the size of the other reference is
2061 at least as large as the alignment, assume no other overlap. */
2062 if (GET_CODE (x) == AND && CONST_INT_P (XEXP (x, 1)))
2064 if (GET_CODE (y) == AND || ysize < -INTVAL (XEXP (x, 1)))
2065 xsize = -1;
2066 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)), ysize, y, c);
2068 if (GET_CODE (y) == AND && CONST_INT_P (XEXP (y, 1)))
2070 /* ??? If we are indexing far enough into the array/structure, we
2071 may yet be able to determine that we can not overlap. But we
2072 also need to that we are far enough from the end not to overlap
2073 a following reference, so we do nothing with that for now. */
2074 if (GET_CODE (x) == AND || xsize < -INTVAL (XEXP (y, 1)))
2075 ysize = -1;
2076 return memrefs_conflict_p (xsize, x, ysize, canon_rtx (XEXP (y, 0)), c);
2079 if (CONSTANT_P (x))
2081 if (CONST_INT_P (x) && CONST_INT_P (y))
2083 c += (INTVAL (y) - INTVAL (x));
2084 return (xsize <= 0 || ysize <= 0
2085 || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
2088 if (GET_CODE (x) == CONST)
2090 if (GET_CODE (y) == CONST)
2091 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
2092 ysize, canon_rtx (XEXP (y, 0)), c);
2093 else
2094 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
2095 ysize, y, c);
2097 if (GET_CODE (y) == CONST)
2098 return memrefs_conflict_p (xsize, x, ysize,
2099 canon_rtx (XEXP (y, 0)), c);
2101 if (CONSTANT_P (y))
2102 return (xsize <= 0 || ysize <= 0
2103 || (rtx_equal_for_memref_p (x, y)
2104 && ((c >= 0 && xsize > c) || (c < 0 && ysize+c > 0))));
2106 return -1;
2109 return -1;
2112 /* Functions to compute memory dependencies.
2114 Since we process the insns in execution order, we can build tables
2115 to keep track of what registers are fixed (and not aliased), what registers
2116 are varying in known ways, and what registers are varying in unknown
2117 ways.
2119 If both memory references are volatile, then there must always be a
2120 dependence between the two references, since their order can not be
2121 changed. A volatile and non-volatile reference can be interchanged
2122 though.
2124 We also must allow AND addresses, because they may generate accesses
2125 outside the object being referenced. This is used to generate aligned
2126 addresses from unaligned addresses, for instance, the alpha
2127 storeqi_unaligned pattern. */
2129 /* Read dependence: X is read after read in MEM takes place. There can
2130 only be a dependence here if both reads are volatile. */
2133 read_dependence (const_rtx mem, const_rtx x)
2135 return MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem);
2138 /* Returns nonzero if something about the mode or address format MEM1
2139 indicates that it might well alias *anything*. */
2141 static int
2142 aliases_everything_p (const_rtx mem)
2144 if (GET_CODE (XEXP (mem, 0)) == AND)
2145 /* If the address is an AND, it's very hard to know at what it is
2146 actually pointing. */
2147 return 1;
2149 return 0;
2152 /* Return true if we can determine that the fields referenced cannot
2153 overlap for any pair of objects. */
2155 static bool
2156 nonoverlapping_component_refs_p (const_tree x, const_tree y)
2158 const_tree fieldx, fieldy, typex, typey, orig_y;
2160 if (!flag_strict_aliasing)
2161 return false;
2165 /* The comparison has to be done at a common type, since we don't
2166 know how the inheritance hierarchy works. */
2167 orig_y = y;
2170 fieldx = TREE_OPERAND (x, 1);
2171 typex = TYPE_MAIN_VARIANT (DECL_FIELD_CONTEXT (fieldx));
2173 y = orig_y;
2176 fieldy = TREE_OPERAND (y, 1);
2177 typey = TYPE_MAIN_VARIANT (DECL_FIELD_CONTEXT (fieldy));
2179 if (typex == typey)
2180 goto found;
2182 y = TREE_OPERAND (y, 0);
2184 while (y && TREE_CODE (y) == COMPONENT_REF);
2186 x = TREE_OPERAND (x, 0);
2188 while (x && TREE_CODE (x) == COMPONENT_REF);
2189 /* Never found a common type. */
2190 return false;
2192 found:
2193 /* If we're left with accessing different fields of a structure,
2194 then no overlap. */
2195 if (TREE_CODE (typex) == RECORD_TYPE
2196 && fieldx != fieldy)
2197 return true;
2199 /* The comparison on the current field failed. If we're accessing
2200 a very nested structure, look at the next outer level. */
2201 x = TREE_OPERAND (x, 0);
2202 y = TREE_OPERAND (y, 0);
2204 while (x && y
2205 && TREE_CODE (x) == COMPONENT_REF
2206 && TREE_CODE (y) == COMPONENT_REF);
2208 return false;
2211 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
2213 static tree
2214 decl_for_component_ref (tree x)
2218 x = TREE_OPERAND (x, 0);
2220 while (x && TREE_CODE (x) == COMPONENT_REF);
2222 return x && DECL_P (x) ? x : NULL_TREE;
2225 /* Walk up the COMPONENT_REF list in X and adjust *OFFSET to compensate
2226 for the offset of the field reference. *KNOWN_P says whether the
2227 offset is known. */
2229 static void
2230 adjust_offset_for_component_ref (tree x, bool *known_p,
2231 HOST_WIDE_INT *offset)
2233 if (!*known_p)
2234 return;
2237 tree xoffset = component_ref_field_offset (x);
2238 tree field = TREE_OPERAND (x, 1);
2240 if (! host_integerp (xoffset, 1))
2242 *known_p = false;
2243 return;
2245 *offset += (tree_low_cst (xoffset, 1)
2246 + (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
2247 / BITS_PER_UNIT));
2249 x = TREE_OPERAND (x, 0);
2251 while (x && TREE_CODE (x) == COMPONENT_REF);
2254 /* Return nonzero if we can determine the exprs corresponding to memrefs
2255 X and Y and they do not overlap.
2256 If LOOP_VARIANT is set, skip offset-based disambiguation */
2259 nonoverlapping_memrefs_p (const_rtx x, const_rtx y, bool loop_invariant)
2261 tree exprx = MEM_EXPR (x), expry = MEM_EXPR (y);
2262 rtx rtlx, rtly;
2263 rtx basex, basey;
2264 bool moffsetx_known_p, moffsety_known_p;
2265 HOST_WIDE_INT moffsetx = 0, moffsety = 0;
2266 HOST_WIDE_INT offsetx = 0, offsety = 0, sizex, sizey, tem;
2268 /* Unless both have exprs, we can't tell anything. */
2269 if (exprx == 0 || expry == 0)
2270 return 0;
2272 /* For spill-slot accesses make sure we have valid offsets. */
2273 if ((exprx == get_spill_slot_decl (false)
2274 && ! MEM_OFFSET_KNOWN_P (x))
2275 || (expry == get_spill_slot_decl (false)
2276 && ! MEM_OFFSET_KNOWN_P (y)))
2277 return 0;
2279 /* If both are field references, we may be able to determine something. */
2280 if (TREE_CODE (exprx) == COMPONENT_REF
2281 && TREE_CODE (expry) == COMPONENT_REF
2282 && nonoverlapping_component_refs_p (exprx, expry))
2283 return 1;
2286 /* If the field reference test failed, look at the DECLs involved. */
2287 moffsetx_known_p = MEM_OFFSET_KNOWN_P (x);
2288 if (moffsetx_known_p)
2289 moffsetx = MEM_OFFSET (x);
2290 if (TREE_CODE (exprx) == COMPONENT_REF)
2292 tree t = decl_for_component_ref (exprx);
2293 if (! t)
2294 return 0;
2295 adjust_offset_for_component_ref (exprx, &moffsetx_known_p, &moffsetx);
2296 exprx = t;
2299 moffsety_known_p = MEM_OFFSET_KNOWN_P (y);
2300 if (moffsety_known_p)
2301 moffsety = MEM_OFFSET (y);
2302 if (TREE_CODE (expry) == COMPONENT_REF)
2304 tree t = decl_for_component_ref (expry);
2305 if (! t)
2306 return 0;
2307 adjust_offset_for_component_ref (expry, &moffsety_known_p, &moffsety);
2308 expry = t;
2311 if (! DECL_P (exprx) || ! DECL_P (expry))
2312 return 0;
2314 /* With invalid code we can end up storing into the constant pool.
2315 Bail out to avoid ICEing when creating RTL for this.
2316 See gfortran.dg/lto/20091028-2_0.f90. */
2317 if (TREE_CODE (exprx) == CONST_DECL
2318 || TREE_CODE (expry) == CONST_DECL)
2319 return 1;
2321 rtlx = DECL_RTL (exprx);
2322 rtly = DECL_RTL (expry);
2324 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
2325 can't overlap unless they are the same because we never reuse that part
2326 of the stack frame used for locals for spilled pseudos. */
2327 if ((!MEM_P (rtlx) || !MEM_P (rtly))
2328 && ! rtx_equal_p (rtlx, rtly))
2329 return 1;
2331 /* If we have MEMs refering to different address spaces (which can
2332 potentially overlap), we cannot easily tell from the addresses
2333 whether the references overlap. */
2334 if (MEM_P (rtlx) && MEM_P (rtly)
2335 && MEM_ADDR_SPACE (rtlx) != MEM_ADDR_SPACE (rtly))
2336 return 0;
2338 /* Get the base and offsets of both decls. If either is a register, we
2339 know both are and are the same, so use that as the base. The only
2340 we can avoid overlap is if we can deduce that they are nonoverlapping
2341 pieces of that decl, which is very rare. */
2342 basex = MEM_P (rtlx) ? XEXP (rtlx, 0) : rtlx;
2343 if (GET_CODE (basex) == PLUS && CONST_INT_P (XEXP (basex, 1)))
2344 offsetx = INTVAL (XEXP (basex, 1)), basex = XEXP (basex, 0);
2346 basey = MEM_P (rtly) ? XEXP (rtly, 0) : rtly;
2347 if (GET_CODE (basey) == PLUS && CONST_INT_P (XEXP (basey, 1)))
2348 offsety = INTVAL (XEXP (basey, 1)), basey = XEXP (basey, 0);
2350 /* If the bases are different, we know they do not overlap if both
2351 are constants or if one is a constant and the other a pointer into the
2352 stack frame. Otherwise a different base means we can't tell if they
2353 overlap or not. */
2354 if (! rtx_equal_p (basex, basey))
2355 return ((CONSTANT_P (basex) && CONSTANT_P (basey))
2356 || (CONSTANT_P (basex) && REG_P (basey)
2357 && REGNO_PTR_FRAME_P (REGNO (basey)))
2358 || (CONSTANT_P (basey) && REG_P (basex)
2359 && REGNO_PTR_FRAME_P (REGNO (basex))));
2361 /* Offset based disambiguation not appropriate for loop invariant */
2362 if (loop_invariant)
2363 return 0;
2365 sizex = (!MEM_P (rtlx) ? (int) GET_MODE_SIZE (GET_MODE (rtlx))
2366 : MEM_SIZE_KNOWN_P (rtlx) ? MEM_SIZE (rtlx)
2367 : -1);
2368 sizey = (!MEM_P (rtly) ? (int) GET_MODE_SIZE (GET_MODE (rtly))
2369 : MEM_SIZE_KNOWN_P (rtly) ? MEM_SIZE (rtly)
2370 : -1);
2372 /* If we have an offset for either memref, it can update the values computed
2373 above. */
2374 if (moffsetx_known_p)
2375 offsetx += moffsetx, sizex -= moffsetx;
2376 if (moffsety_known_p)
2377 offsety += moffsety, sizey -= moffsety;
2379 /* If a memref has both a size and an offset, we can use the smaller size.
2380 We can't do this if the offset isn't known because we must view this
2381 memref as being anywhere inside the DECL's MEM. */
2382 if (MEM_SIZE_KNOWN_P (x) && moffsetx_known_p)
2383 sizex = MEM_SIZE (x);
2384 if (MEM_SIZE_KNOWN_P (y) && moffsety_known_p)
2385 sizey = MEM_SIZE (y);
2387 /* Put the values of the memref with the lower offset in X's values. */
2388 if (offsetx > offsety)
2390 tem = offsetx, offsetx = offsety, offsety = tem;
2391 tem = sizex, sizex = sizey, sizey = tem;
2394 /* If we don't know the size of the lower-offset value, we can't tell
2395 if they conflict. Otherwise, we do the test. */
2396 return sizex >= 0 && offsety >= offsetx + sizex;
2399 /* Helper for true_dependence and canon_true_dependence.
2400 Checks for true dependence: X is read after store in MEM takes place.
2402 If MEM_CANONICALIZED is FALSE, then X_ADDR and MEM_ADDR should be
2403 NULL_RTX, and the canonical addresses of MEM and X are both computed
2404 here. If MEM_CANONICALIZED, then MEM must be already canonicalized.
2406 If X_ADDR is non-NULL, it is used in preference of XEXP (x, 0).
2408 Returns 1 if there is a true dependence, 0 otherwise. */
2410 static int
2411 true_dependence_1 (const_rtx mem, enum machine_mode mem_mode, rtx mem_addr,
2412 const_rtx x, rtx x_addr, bool mem_canonicalized)
2414 rtx base;
2415 int ret;
2417 gcc_checking_assert (mem_canonicalized ? (mem_addr != NULL_RTX)
2418 : (mem_addr == NULL_RTX && x_addr == NULL_RTX));
2420 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2421 return 1;
2423 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2424 This is used in epilogue deallocation functions, and in cselib. */
2425 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
2426 return 1;
2427 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
2428 return 1;
2429 if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER
2430 || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER)
2431 return 1;
2433 /* Read-only memory is by definition never modified, and therefore can't
2434 conflict with anything. We don't expect to find read-only set on MEM,
2435 but stupid user tricks can produce them, so don't die. */
2436 if (MEM_READONLY_P (x))
2437 return 0;
2439 /* If we have MEMs refering to different address spaces (which can
2440 potentially overlap), we cannot easily tell from the addresses
2441 whether the references overlap. */
2442 if (MEM_ADDR_SPACE (mem) != MEM_ADDR_SPACE (x))
2443 return 1;
2445 if (! mem_addr)
2447 mem_addr = XEXP (mem, 0);
2448 if (mem_mode == VOIDmode)
2449 mem_mode = GET_MODE (mem);
2452 if (! x_addr)
2454 x_addr = XEXP (x, 0);
2455 if (!((GET_CODE (x_addr) == VALUE
2456 && GET_CODE (mem_addr) != VALUE
2457 && reg_mentioned_p (x_addr, mem_addr))
2458 || (GET_CODE (x_addr) != VALUE
2459 && GET_CODE (mem_addr) == VALUE
2460 && reg_mentioned_p (mem_addr, x_addr))))
2462 x_addr = get_addr (x_addr);
2463 if (! mem_canonicalized)
2464 mem_addr = get_addr (mem_addr);
2468 base = find_base_term (x_addr);
2469 if (base && (GET_CODE (base) == LABEL_REF
2470 || (GET_CODE (base) == SYMBOL_REF
2471 && CONSTANT_POOL_ADDRESS_P (base))))
2472 return 0;
2474 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode))
2475 return 0;
2477 x_addr = canon_rtx (x_addr);
2478 if (!mem_canonicalized)
2479 mem_addr = canon_rtx (mem_addr);
2481 if ((ret = memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
2482 SIZE_FOR_MODE (x), x_addr, 0)) != -1)
2483 return ret;
2485 if (DIFFERENT_ALIAS_SETS_P (x, mem))
2486 return 0;
2488 if (nonoverlapping_memrefs_p (mem, x, false))
2489 return 0;
2491 if (aliases_everything_p (x))
2492 return 1;
2494 /* We cannot use aliases_everything_p to test MEM, since we must look
2495 at MEM_ADDR, rather than XEXP (mem, 0). */
2496 if (GET_CODE (mem_addr) == AND)
2497 return 1;
2499 /* ??? In true_dependence we also allow BLKmode to alias anything. Why
2500 don't we do this in anti_dependence and output_dependence? */
2501 if (mem_mode == BLKmode || GET_MODE (x) == BLKmode)
2502 return 1;
2504 return rtx_refs_may_alias_p (x, mem, true);
2507 /* True dependence: X is read after store in MEM takes place. */
2510 true_dependence (const_rtx mem, enum machine_mode mem_mode, const_rtx x)
2512 return true_dependence_1 (mem, mem_mode, NULL_RTX,
2513 x, NULL_RTX, /*mem_canonicalized=*/false);
2516 /* Canonical true dependence: X is read after store in MEM takes place.
2517 Variant of true_dependence which assumes MEM has already been
2518 canonicalized (hence we no longer do that here).
2519 The mem_addr argument has been added, since true_dependence_1 computed
2520 this value prior to canonicalizing. */
2523 canon_true_dependence (const_rtx mem, enum machine_mode mem_mode, rtx mem_addr,
2524 const_rtx x, rtx x_addr)
2526 return true_dependence_1 (mem, mem_mode, mem_addr,
2527 x, x_addr, /*mem_canonicalized=*/true);
2530 /* Returns nonzero if a write to X might alias a previous read from
2531 (or, if WRITEP is nonzero, a write to) MEM. */
2533 static int
2534 write_dependence_p (const_rtx mem, const_rtx x, int writep)
2536 rtx x_addr, mem_addr;
2537 rtx base;
2538 int ret;
2540 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2541 return 1;
2543 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2544 This is used in epilogue deallocation functions. */
2545 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
2546 return 1;
2547 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
2548 return 1;
2549 if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER
2550 || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER)
2551 return 1;
2553 /* A read from read-only memory can't conflict with read-write memory. */
2554 if (!writep && MEM_READONLY_P (mem))
2555 return 0;
2557 /* If we have MEMs refering to different address spaces (which can
2558 potentially overlap), we cannot easily tell from the addresses
2559 whether the references overlap. */
2560 if (MEM_ADDR_SPACE (mem) != MEM_ADDR_SPACE (x))
2561 return 1;
2563 x_addr = XEXP (x, 0);
2564 mem_addr = XEXP (mem, 0);
2565 if (!((GET_CODE (x_addr) == VALUE
2566 && GET_CODE (mem_addr) != VALUE
2567 && reg_mentioned_p (x_addr, mem_addr))
2568 || (GET_CODE (x_addr) != VALUE
2569 && GET_CODE (mem_addr) == VALUE
2570 && reg_mentioned_p (mem_addr, x_addr))))
2572 x_addr = get_addr (x_addr);
2573 mem_addr = get_addr (mem_addr);
2576 if (! writep)
2578 base = find_base_term (mem_addr);
2579 if (base && (GET_CODE (base) == LABEL_REF
2580 || (GET_CODE (base) == SYMBOL_REF
2581 && CONSTANT_POOL_ADDRESS_P (base))))
2582 return 0;
2585 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x),
2586 GET_MODE (mem)))
2587 return 0;
2589 x_addr = canon_rtx (x_addr);
2590 mem_addr = canon_rtx (mem_addr);
2592 if ((ret = memrefs_conflict_p (SIZE_FOR_MODE (mem), mem_addr,
2593 SIZE_FOR_MODE (x), x_addr, 0)) != -1)
2594 return ret;
2596 if (nonoverlapping_memrefs_p (x, mem, false))
2597 return 0;
2599 return rtx_refs_may_alias_p (x, mem, false);
2602 /* Anti dependence: X is written after read in MEM takes place. */
2605 anti_dependence (const_rtx mem, const_rtx x)
2607 return write_dependence_p (mem, x, /*writep=*/0);
2610 /* Output dependence: X is written after store in MEM takes place. */
2613 output_dependence (const_rtx mem, const_rtx x)
2615 return write_dependence_p (mem, x, /*writep=*/1);
2620 /* Check whether X may be aliased with MEM. Don't do offset-based
2621 memory disambiguation & TBAA. */
2623 may_alias_p (const_rtx mem, const_rtx x)
2625 rtx x_addr, mem_addr;
2627 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2628 return 1;
2630 /* ??? In true_dependence we also allow BLKmode to alias anything. */
2631 if (GET_MODE (mem) == BLKmode || GET_MODE (x) == BLKmode)
2632 return 1;
2634 if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER
2635 || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER)
2636 return 1;
2638 /* Read-only memory is by definition never modified, and therefore can't
2639 conflict with anything. We don't expect to find read-only set on MEM,
2640 but stupid user tricks can produce them, so don't die. */
2641 if (MEM_READONLY_P (x))
2642 return 0;
2644 /* If we have MEMs refering to different address spaces (which can
2645 potentially overlap), we cannot easily tell from the addresses
2646 whether the references overlap. */
2647 if (MEM_ADDR_SPACE (mem) != MEM_ADDR_SPACE (x))
2648 return 1;
2650 x_addr = XEXP (x, 0);
2651 mem_addr = XEXP (mem, 0);
2652 if (!((GET_CODE (x_addr) == VALUE
2653 && GET_CODE (mem_addr) != VALUE
2654 && reg_mentioned_p (x_addr, mem_addr))
2655 || (GET_CODE (x_addr) != VALUE
2656 && GET_CODE (mem_addr) == VALUE
2657 && reg_mentioned_p (mem_addr, x_addr))))
2659 x_addr = get_addr (x_addr);
2660 mem_addr = get_addr (mem_addr);
2663 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), GET_MODE (mem_addr)))
2664 return 0;
2666 x_addr = canon_rtx (x_addr);
2667 mem_addr = canon_rtx (mem_addr);
2669 if (nonoverlapping_memrefs_p (mem, x, true))
2670 return 0;
2672 if (aliases_everything_p (x))
2673 return 1;
2675 /* We cannot use aliases_everything_p to test MEM, since we must look
2676 at MEM_ADDR, rather than XEXP (mem, 0). */
2677 if (GET_CODE (mem_addr) == AND)
2678 return 1;
2680 /* TBAA not valid for loop_invarint */
2681 return rtx_refs_may_alias_p (x, mem, false);
2684 void
2685 init_alias_target (void)
2687 int i;
2689 memset (static_reg_base_value, 0, sizeof static_reg_base_value);
2691 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2692 /* Check whether this register can hold an incoming pointer
2693 argument. FUNCTION_ARG_REGNO_P tests outgoing register
2694 numbers, so translate if necessary due to register windows. */
2695 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i))
2696 && HARD_REGNO_MODE_OK (i, Pmode))
2697 static_reg_base_value[i]
2698 = gen_rtx_ADDRESS (VOIDmode, gen_rtx_REG (Pmode, i));
2700 static_reg_base_value[STACK_POINTER_REGNUM]
2701 = gen_rtx_ADDRESS (Pmode, stack_pointer_rtx);
2702 static_reg_base_value[ARG_POINTER_REGNUM]
2703 = gen_rtx_ADDRESS (Pmode, arg_pointer_rtx);
2704 static_reg_base_value[FRAME_POINTER_REGNUM]
2705 = gen_rtx_ADDRESS (Pmode, frame_pointer_rtx);
2706 #if !HARD_FRAME_POINTER_IS_FRAME_POINTER
2707 static_reg_base_value[HARD_FRAME_POINTER_REGNUM]
2708 = gen_rtx_ADDRESS (Pmode, hard_frame_pointer_rtx);
2709 #endif
2712 /* Set MEMORY_MODIFIED when X modifies DATA (that is assumed
2713 to be memory reference. */
2714 static bool memory_modified;
2715 static void
2716 memory_modified_1 (rtx x, const_rtx pat ATTRIBUTE_UNUSED, void *data)
2718 if (MEM_P (x))
2720 if (anti_dependence (x, (const_rtx)data) || output_dependence (x, (const_rtx)data))
2721 memory_modified = true;
2726 /* Return true when INSN possibly modify memory contents of MEM
2727 (i.e. address can be modified). */
2728 bool
2729 memory_modified_in_insn_p (const_rtx mem, const_rtx insn)
2731 if (!INSN_P (insn))
2732 return false;
2733 memory_modified = false;
2734 note_stores (PATTERN (insn), memory_modified_1, CONST_CAST_RTX(mem));
2735 return memory_modified;
2738 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
2739 array. */
2741 void
2742 init_alias_analysis (void)
2744 unsigned int maxreg = max_reg_num ();
2745 int changed, pass;
2746 int i;
2747 unsigned int ui;
2748 rtx insn;
2750 timevar_push (TV_ALIAS_ANALYSIS);
2752 reg_known_value_size = maxreg - FIRST_PSEUDO_REGISTER;
2753 reg_known_value = ggc_alloc_cleared_vec_rtx (reg_known_value_size);
2754 reg_known_equiv_p = XCNEWVEC (bool, reg_known_value_size);
2756 /* If we have memory allocated from the previous run, use it. */
2757 if (old_reg_base_value)
2758 reg_base_value = old_reg_base_value;
2760 if (reg_base_value)
2761 VEC_truncate (rtx, reg_base_value, 0);
2763 VEC_safe_grow_cleared (rtx, gc, reg_base_value, maxreg);
2765 new_reg_base_value = XNEWVEC (rtx, maxreg);
2766 reg_seen = XNEWVEC (char, maxreg);
2768 /* The basic idea is that each pass through this loop will use the
2769 "constant" information from the previous pass to propagate alias
2770 information through another level of assignments.
2772 This could get expensive if the assignment chains are long. Maybe
2773 we should throttle the number of iterations, possibly based on
2774 the optimization level or flag_expensive_optimizations.
2776 We could propagate more information in the first pass by making use
2777 of DF_REG_DEF_COUNT to determine immediately that the alias information
2778 for a pseudo is "constant".
2780 A program with an uninitialized variable can cause an infinite loop
2781 here. Instead of doing a full dataflow analysis to detect such problems
2782 we just cap the number of iterations for the loop.
2784 The state of the arrays for the set chain in question does not matter
2785 since the program has undefined behavior. */
2787 pass = 0;
2790 /* Assume nothing will change this iteration of the loop. */
2791 changed = 0;
2793 /* We want to assign the same IDs each iteration of this loop, so
2794 start counting from zero each iteration of the loop. */
2795 unique_id = 0;
2797 /* We're at the start of the function each iteration through the
2798 loop, so we're copying arguments. */
2799 copying_arguments = true;
2801 /* Wipe the potential alias information clean for this pass. */
2802 memset (new_reg_base_value, 0, maxreg * sizeof (rtx));
2804 /* Wipe the reg_seen array clean. */
2805 memset (reg_seen, 0, maxreg);
2807 /* Mark all hard registers which may contain an address.
2808 The stack, frame and argument pointers may contain an address.
2809 An argument register which can hold a Pmode value may contain
2810 an address even if it is not in BASE_REGS.
2812 The address expression is VOIDmode for an argument and
2813 Pmode for other registers. */
2815 memcpy (new_reg_base_value, static_reg_base_value,
2816 FIRST_PSEUDO_REGISTER * sizeof (rtx));
2818 /* Walk the insns adding values to the new_reg_base_value array. */
2819 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2821 if (INSN_P (insn))
2823 rtx note, set;
2825 #if defined (HAVE_prologue) || defined (HAVE_epilogue)
2826 /* The prologue/epilogue insns are not threaded onto the
2827 insn chain until after reload has completed. Thus,
2828 there is no sense wasting time checking if INSN is in
2829 the prologue/epilogue until after reload has completed. */
2830 if (reload_completed
2831 && prologue_epilogue_contains (insn))
2832 continue;
2833 #endif
2835 /* If this insn has a noalias note, process it, Otherwise,
2836 scan for sets. A simple set will have no side effects
2837 which could change the base value of any other register. */
2839 if (GET_CODE (PATTERN (insn)) == SET
2840 && REG_NOTES (insn) != 0
2841 && find_reg_note (insn, REG_NOALIAS, NULL_RTX))
2842 record_set (SET_DEST (PATTERN (insn)), NULL_RTX, NULL);
2843 else
2844 note_stores (PATTERN (insn), record_set, NULL);
2846 set = single_set (insn);
2848 if (set != 0
2849 && REG_P (SET_DEST (set))
2850 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER)
2852 unsigned int regno = REGNO (SET_DEST (set));
2853 rtx src = SET_SRC (set);
2854 rtx t;
2856 note = find_reg_equal_equiv_note (insn);
2857 if (note && REG_NOTE_KIND (note) == REG_EQUAL
2858 && DF_REG_DEF_COUNT (regno) != 1)
2859 note = NULL_RTX;
2861 if (note != NULL_RTX
2862 && GET_CODE (XEXP (note, 0)) != EXPR_LIST
2863 && ! rtx_varies_p (XEXP (note, 0), 1)
2864 && ! reg_overlap_mentioned_p (SET_DEST (set),
2865 XEXP (note, 0)))
2867 set_reg_known_value (regno, XEXP (note, 0));
2868 set_reg_known_equiv_p (regno,
2869 REG_NOTE_KIND (note) == REG_EQUIV);
2871 else if (DF_REG_DEF_COUNT (regno) == 1
2872 && GET_CODE (src) == PLUS
2873 && REG_P (XEXP (src, 0))
2874 && (t = get_reg_known_value (REGNO (XEXP (src, 0))))
2875 && CONST_INT_P (XEXP (src, 1)))
2877 t = plus_constant (t, INTVAL (XEXP (src, 1)));
2878 set_reg_known_value (regno, t);
2879 set_reg_known_equiv_p (regno, 0);
2881 else if (DF_REG_DEF_COUNT (regno) == 1
2882 && ! rtx_varies_p (src, 1))
2884 set_reg_known_value (regno, src);
2885 set_reg_known_equiv_p (regno, 0);
2889 else if (NOTE_P (insn)
2890 && NOTE_KIND (insn) == NOTE_INSN_FUNCTION_BEG)
2891 copying_arguments = false;
2894 /* Now propagate values from new_reg_base_value to reg_base_value. */
2895 gcc_assert (maxreg == (unsigned int) max_reg_num ());
2897 for (ui = 0; ui < maxreg; ui++)
2899 if (new_reg_base_value[ui]
2900 && new_reg_base_value[ui] != VEC_index (rtx, reg_base_value, ui)
2901 && ! rtx_equal_p (new_reg_base_value[ui],
2902 VEC_index (rtx, reg_base_value, ui)))
2904 VEC_replace (rtx, reg_base_value, ui, new_reg_base_value[ui]);
2905 changed = 1;
2909 while (changed && ++pass < MAX_ALIAS_LOOP_PASSES);
2911 /* Fill in the remaining entries. */
2912 for (i = 0; i < (int)reg_known_value_size; i++)
2913 if (reg_known_value[i] == 0)
2914 reg_known_value[i] = regno_reg_rtx[i + FIRST_PSEUDO_REGISTER];
2916 /* Clean up. */
2917 free (new_reg_base_value);
2918 new_reg_base_value = 0;
2919 free (reg_seen);
2920 reg_seen = 0;
2921 timevar_pop (TV_ALIAS_ANALYSIS);
2924 /* Equate REG_BASE_VALUE (reg1) to REG_BASE_VALUE (reg2).
2925 Special API for var-tracking pass purposes. */
2927 void
2928 vt_equate_reg_base_value (const_rtx reg1, const_rtx reg2)
2930 VEC_replace (rtx, reg_base_value, REGNO (reg1), REG_BASE_VALUE (reg2));
2933 void
2934 end_alias_analysis (void)
2936 old_reg_base_value = reg_base_value;
2937 ggc_free (reg_known_value);
2938 reg_known_value = 0;
2939 reg_known_value_size = 0;
2940 free (reg_known_equiv_p);
2941 reg_known_equiv_p = 0;
2944 #include "gt-alias.h"