* testsuite/libgomp.oacc-c-c++-common/collapse-2.c: Sequential
[official-gcc.git] / gcc / alias.c
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1 /* Alias analysis for GNU C
2 Copyright (C) 1997-2015 Free Software Foundation, Inc.
3 Contributed by John Carr (jfc@mit.edu).
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
10 version.
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
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 "df.h"
30 #include "tm_p.h"
31 #include "gimple-ssa.h"
32 #include "emit-rtl.h"
33 #include "alias.h"
34 #include "fold-const.h"
35 #include "varasm.h"
36 #include "cselib.h"
37 #include "langhooks.h"
38 #include "cfganal.h"
39 #include "rtl-iter.h"
41 /* The aliasing API provided here solves related but different problems:
43 Say there exists (in c)
45 struct X {
46 struct Y y1;
47 struct Z z2;
48 } x1, *px1, *px2;
50 struct Y y2, *py;
51 struct Z z2, *pz;
54 py = &x1.y1;
55 px2 = &x1;
57 Consider the four questions:
59 Can a store to x1 interfere with px2->y1?
60 Can a store to x1 interfere with px2->z2?
61 Can a store to x1 change the value pointed to by with py?
62 Can a store to x1 change the value pointed to by with pz?
64 The answer to these questions can be yes, yes, yes, and maybe.
66 The first two questions can be answered with a simple examination
67 of the type system. If structure X contains a field of type Y then
68 a store through a pointer to an X can overwrite any field that is
69 contained (recursively) in an X (unless we know that px1 != px2).
71 The last two questions can be solved in the same way as the first
72 two questions but this is too conservative. The observation is
73 that in some cases we can know which (if any) fields are addressed
74 and if those addresses are used in bad ways. This analysis may be
75 language specific. In C, arbitrary operations may be applied to
76 pointers. However, there is some indication that this may be too
77 conservative for some C++ types.
79 The pass ipa-type-escape does this analysis for the types whose
80 instances do not escape across the compilation boundary.
82 Historically in GCC, these two problems were combined and a single
83 data structure that was used to represent the solution to these
84 problems. We now have two similar but different data structures,
85 The data structure to solve the last two questions is similar to
86 the first, but does not contain the fields whose address are never
87 taken. For types that do escape the compilation unit, the data
88 structures will have identical information.
91 /* The alias sets assigned to MEMs assist the back-end in determining
92 which MEMs can alias which other MEMs. In general, two MEMs in
93 different alias sets cannot alias each other, with one important
94 exception. Consider something like:
96 struct S { int i; double d; };
98 a store to an `S' can alias something of either type `int' or type
99 `double'. (However, a store to an `int' cannot alias a `double'
100 and vice versa.) We indicate this via a tree structure that looks
101 like:
102 struct S
105 |/_ _\|
106 int double
108 (The arrows are directed and point downwards.)
109 In this situation we say the alias set for `struct S' is the
110 `superset' and that those for `int' and `double' are `subsets'.
112 To see whether two alias sets can point to the same memory, we must
113 see if either alias set is a subset of the other. We need not trace
114 past immediate descendants, however, since we propagate all
115 grandchildren up one level.
117 Alias set zero is implicitly a superset of all other alias sets.
118 However, this is no actual entry for alias set zero. It is an
119 error to attempt to explicitly construct a subset of zero. */
121 struct alias_set_hash : int_hash <int, INT_MIN, INT_MIN + 1> {};
123 struct GTY(()) alias_set_entry {
124 /* The alias set number, as stored in MEM_ALIAS_SET. */
125 alias_set_type alias_set;
127 /* The children of the alias set. These are not just the immediate
128 children, but, in fact, all descendants. So, if we have:
130 struct T { struct S s; float f; }
132 continuing our example above, the children here will be all of
133 `int', `double', `float', and `struct S'. */
134 hash_map<alias_set_hash, int> *children;
136 /* Nonzero if would have a child of zero: this effectively makes this
137 alias set the same as alias set zero. */
138 bool has_zero_child;
139 /* Nonzero if alias set corresponds to pointer type itself (i.e. not to
140 aggregate contaiing pointer.
141 This is used for a special case where we need an universal pointer type
142 compatible with all other pointer types. */
143 bool is_pointer;
144 /* Nonzero if is_pointer or if one of childs have has_pointer set. */
145 bool has_pointer;
148 static int rtx_equal_for_memref_p (const_rtx, const_rtx);
149 static int memrefs_conflict_p (int, rtx, int, rtx, HOST_WIDE_INT);
150 static void record_set (rtx, const_rtx, void *);
151 static int base_alias_check (rtx, rtx, rtx, rtx, machine_mode,
152 machine_mode);
153 static rtx find_base_value (rtx);
154 static int mems_in_disjoint_alias_sets_p (const_rtx, const_rtx);
155 static alias_set_entry *get_alias_set_entry (alias_set_type);
156 static tree decl_for_component_ref (tree);
157 static int write_dependence_p (const_rtx,
158 const_rtx, machine_mode, rtx,
159 bool, bool, bool);
161 static void memory_modified_1 (rtx, const_rtx, void *);
163 /* Query statistics for the different low-level disambiguators.
164 A high-level query may trigger multiple of them. */
166 static struct {
167 unsigned long long num_alias_zero;
168 unsigned long long num_same_alias_set;
169 unsigned long long num_same_objects;
170 unsigned long long num_volatile;
171 unsigned long long num_dag;
172 unsigned long long num_universal;
173 unsigned long long num_disambiguated;
174 } alias_stats;
177 /* Set up all info needed to perform alias analysis on memory references. */
179 /* Returns the size in bytes of the mode of X. */
180 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
182 /* Cap the number of passes we make over the insns propagating alias
183 information through set chains.
184 ??? 10 is a completely arbitrary choice. This should be based on the
185 maximum loop depth in the CFG, but we do not have this information
186 available (even if current_loops _is_ available). */
187 #define MAX_ALIAS_LOOP_PASSES 10
189 /* reg_base_value[N] gives an address to which register N is related.
190 If all sets after the first add or subtract to the current value
191 or otherwise modify it so it does not point to a different top level
192 object, reg_base_value[N] is equal to the address part of the source
193 of the first set.
195 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
196 expressions represent three types of base:
198 1. incoming arguments. There is just one ADDRESS to represent all
199 arguments, since we do not know at this level whether accesses
200 based on different arguments can alias. The ADDRESS has id 0.
202 2. stack_pointer_rtx, frame_pointer_rtx, hard_frame_pointer_rtx
203 (if distinct from frame_pointer_rtx) and arg_pointer_rtx.
204 Each of these rtxes has a separate ADDRESS associated with it,
205 each with a negative id.
207 GCC is (and is required to be) precise in which register it
208 chooses to access a particular region of stack. We can therefore
209 assume that accesses based on one of these rtxes do not alias
210 accesses based on another of these rtxes.
212 3. bases that are derived from malloc()ed memory (REG_NOALIAS).
213 Each such piece of memory has a separate ADDRESS associated
214 with it, each with an id greater than 0.
216 Accesses based on one ADDRESS do not alias accesses based on other
217 ADDRESSes. Accesses based on ADDRESSes in groups (2) and (3) do not
218 alias globals either; the ADDRESSes have Pmode to indicate this.
219 The ADDRESS in group (1) _may_ alias globals; it has VOIDmode to
220 indicate this. */
222 static GTY(()) vec<rtx, va_gc> *reg_base_value;
223 static rtx *new_reg_base_value;
225 /* The single VOIDmode ADDRESS that represents all argument bases.
226 It has id 0. */
227 static GTY(()) rtx arg_base_value;
229 /* Used to allocate unique ids to each REG_NOALIAS ADDRESS. */
230 static int unique_id;
232 /* We preserve the copy of old array around to avoid amount of garbage
233 produced. About 8% of garbage produced were attributed to this
234 array. */
235 static GTY((deletable)) vec<rtx, va_gc> *old_reg_base_value;
237 /* Values of XINT (address, 0) of Pmode ADDRESS rtxes for special
238 registers. */
239 #define UNIQUE_BASE_VALUE_SP -1
240 #define UNIQUE_BASE_VALUE_ARGP -2
241 #define UNIQUE_BASE_VALUE_FP -3
242 #define UNIQUE_BASE_VALUE_HFP -4
244 #define static_reg_base_value \
245 (this_target_rtl->x_static_reg_base_value)
247 #define REG_BASE_VALUE(X) \
248 (REGNO (X) < vec_safe_length (reg_base_value) \
249 ? (*reg_base_value)[REGNO (X)] : 0)
251 /* Vector indexed by N giving the initial (unchanging) value known for
252 pseudo-register N. This vector is initialized in init_alias_analysis,
253 and does not change until end_alias_analysis is called. */
254 static GTY(()) vec<rtx, va_gc> *reg_known_value;
256 /* Vector recording for each reg_known_value whether it is due to a
257 REG_EQUIV note. Future passes (viz., reload) may replace the
258 pseudo with the equivalent expression and so we account for the
259 dependences that would be introduced if that happens.
261 The REG_EQUIV notes created in assign_parms may mention the arg
262 pointer, and there are explicit insns in the RTL that modify the
263 arg pointer. Thus we must ensure that such insns don't get
264 scheduled across each other because that would invalidate the
265 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
266 wrong, but solving the problem in the scheduler will likely give
267 better code, so we do it here. */
268 static sbitmap reg_known_equiv_p;
270 /* True when scanning insns from the start of the rtl to the
271 NOTE_INSN_FUNCTION_BEG note. */
272 static bool copying_arguments;
275 /* The splay-tree used to store the various alias set entries. */
276 static GTY (()) vec<alias_set_entry *, va_gc> *alias_sets;
278 /* Build a decomposed reference object for querying the alias-oracle
279 from the MEM rtx and store it in *REF.
280 Returns false if MEM is not suitable for the alias-oracle. */
282 static bool
283 ao_ref_from_mem (ao_ref *ref, const_rtx mem)
285 tree expr = MEM_EXPR (mem);
286 tree base;
288 if (!expr)
289 return false;
291 ao_ref_init (ref, expr);
293 /* Get the base of the reference and see if we have to reject or
294 adjust it. */
295 base = ao_ref_base (ref);
296 if (base == NULL_TREE)
297 return false;
299 /* The tree oracle doesn't like bases that are neither decls
300 nor indirect references of SSA names. */
301 if (!(DECL_P (base)
302 || (TREE_CODE (base) == MEM_REF
303 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
304 || (TREE_CODE (base) == TARGET_MEM_REF
305 && TREE_CODE (TMR_BASE (base)) == SSA_NAME)))
306 return false;
308 /* If this is a reference based on a partitioned decl replace the
309 base with a MEM_REF of the pointer representative we
310 created during stack slot partitioning. */
311 if (TREE_CODE (base) == VAR_DECL
312 && ! is_global_var (base)
313 && cfun->gimple_df->decls_to_pointers != NULL)
315 tree *namep = cfun->gimple_df->decls_to_pointers->get (base);
316 if (namep)
317 ref->base = build_simple_mem_ref (*namep);
320 ref->ref_alias_set = MEM_ALIAS_SET (mem);
322 /* If MEM_OFFSET or MEM_SIZE are unknown what we got from MEM_EXPR
323 is conservative, so trust it. */
324 if (!MEM_OFFSET_KNOWN_P (mem)
325 || !MEM_SIZE_KNOWN_P (mem))
326 return true;
328 /* If MEM_OFFSET/MEM_SIZE get us outside of ref->offset/ref->max_size
329 drop ref->ref. */
330 if (MEM_OFFSET (mem) < 0
331 || (ref->max_size != -1
332 && ((MEM_OFFSET (mem) + MEM_SIZE (mem)) * BITS_PER_UNIT
333 > ref->max_size)))
334 ref->ref = NULL_TREE;
336 /* Refine size and offset we got from analyzing MEM_EXPR by using
337 MEM_SIZE and MEM_OFFSET. */
339 ref->offset += MEM_OFFSET (mem) * BITS_PER_UNIT;
340 ref->size = MEM_SIZE (mem) * BITS_PER_UNIT;
342 /* The MEM may extend into adjacent fields, so adjust max_size if
343 necessary. */
344 if (ref->max_size != -1
345 && ref->size > ref->max_size)
346 ref->max_size = ref->size;
348 /* If MEM_OFFSET and MEM_SIZE get us outside of the base object of
349 the MEM_EXPR punt. This happens for STRICT_ALIGNMENT targets a lot. */
350 if (MEM_EXPR (mem) != get_spill_slot_decl (false)
351 && (ref->offset < 0
352 || (DECL_P (ref->base)
353 && (DECL_SIZE (ref->base) == NULL_TREE
354 || TREE_CODE (DECL_SIZE (ref->base)) != INTEGER_CST
355 || wi::ltu_p (wi::to_offset (DECL_SIZE (ref->base)),
356 ref->offset + ref->size)))))
357 return false;
359 return true;
362 /* Query the alias-oracle on whether the two memory rtx X and MEM may
363 alias. If TBAA_P is set also apply TBAA. Returns true if the
364 two rtxen may alias, false otherwise. */
366 static bool
367 rtx_refs_may_alias_p (const_rtx x, const_rtx mem, bool tbaa_p)
369 ao_ref ref1, ref2;
371 if (!ao_ref_from_mem (&ref1, x)
372 || !ao_ref_from_mem (&ref2, mem))
373 return true;
375 return refs_may_alias_p_1 (&ref1, &ref2,
376 tbaa_p
377 && MEM_ALIAS_SET (x) != 0
378 && MEM_ALIAS_SET (mem) != 0);
381 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
382 such an entry, or NULL otherwise. */
384 static inline alias_set_entry *
385 get_alias_set_entry (alias_set_type alias_set)
387 return (*alias_sets)[alias_set];
390 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
391 the two MEMs cannot alias each other. */
393 static inline int
394 mems_in_disjoint_alias_sets_p (const_rtx mem1, const_rtx mem2)
396 return (flag_strict_aliasing
397 && ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1),
398 MEM_ALIAS_SET (mem2)));
401 /* Return true if the first alias set is a subset of the second. */
403 bool
404 alias_set_subset_of (alias_set_type set1, alias_set_type set2)
406 alias_set_entry *ase2;
408 /* Everything is a subset of the "aliases everything" set. */
409 if (set2 == 0)
410 return true;
412 /* Check if set1 is a subset of set2. */
413 ase2 = get_alias_set_entry (set2);
414 if (ase2 != 0
415 && (ase2->has_zero_child
416 || (ase2->children && ase2->children->get (set1))))
417 return true;
419 /* As a special case we consider alias set of "void *" to be both subset
420 and superset of every alias set of a pointer. This extra symmetry does
421 not matter for alias_sets_conflict_p but it makes aliasing_component_refs_p
422 to return true on the following testcase:
424 void *ptr;
425 char **ptr2=(char **)&ptr;
426 *ptr2 = ...
428 Additionally if a set contains universal pointer, we consider every pointer
429 to be a subset of it, but we do not represent this explicitely - doing so
430 would require us to update transitive closure each time we introduce new
431 pointer type. This makes aliasing_component_refs_p to return true
432 on the following testcase:
434 struct a {void *ptr;}
435 char **ptr = (char **)&a.ptr;
436 ptr = ...
438 This makes void * truly universal pointer type. See pointer handling in
439 get_alias_set for more details. */
440 if (ase2 && ase2->has_pointer)
442 alias_set_entry *ase1 = get_alias_set_entry (set1);
444 if (ase1 && ase1->is_pointer)
446 alias_set_type voidptr_set = TYPE_ALIAS_SET (ptr_type_node);
447 /* If one is ptr_type_node and other is pointer, then we consider
448 them subset of each other. */
449 if (set1 == voidptr_set || set2 == voidptr_set)
450 return true;
451 /* If SET2 contains universal pointer's alias set, then we consdier
452 every (non-universal) pointer. */
453 if (ase2->children && set1 != voidptr_set
454 && ase2->children->get (voidptr_set))
455 return true;
458 return false;
461 /* Return 1 if the two specified alias sets may conflict. */
464 alias_sets_conflict_p (alias_set_type set1, alias_set_type set2)
466 alias_set_entry *ase1;
467 alias_set_entry *ase2;
469 /* The easy case. */
470 if (alias_sets_must_conflict_p (set1, set2))
471 return 1;
473 /* See if the first alias set is a subset of the second. */
474 ase1 = get_alias_set_entry (set1);
475 if (ase1 != 0
476 && ase1->children && ase1->children->get (set2))
478 ++alias_stats.num_dag;
479 return 1;
482 /* Now do the same, but with the alias sets reversed. */
483 ase2 = get_alias_set_entry (set2);
484 if (ase2 != 0
485 && ase2->children && ase2->children->get (set1))
487 ++alias_stats.num_dag;
488 return 1;
491 /* We want void * to be compatible with any other pointer without
492 really dropping it to alias set 0. Doing so would make it
493 compatible with all non-pointer types too.
495 This is not strictly necessary by the C/C++ language
496 standards, but avoids common type punning mistakes. In
497 addition to that, we need the existence of such universal
498 pointer to implement Fortran's C_PTR type (which is defined as
499 type compatible with all C pointers). */
500 if (ase1 && ase2 && ase1->has_pointer && ase2->has_pointer)
502 alias_set_type voidptr_set = TYPE_ALIAS_SET (ptr_type_node);
504 /* If one of the sets corresponds to universal pointer,
505 we consider it to conflict with anything that is
506 or contains pointer. */
507 if (set1 == voidptr_set || set2 == voidptr_set)
509 ++alias_stats.num_universal;
510 return true;
512 /* If one of sets is (non-universal) pointer and the other
513 contains universal pointer, we also get conflict. */
514 if (ase1->is_pointer && set2 != voidptr_set
515 && ase2->children && ase2->children->get (voidptr_set))
517 ++alias_stats.num_universal;
518 return true;
520 if (ase2->is_pointer && set1 != voidptr_set
521 && ase1->children && ase1->children->get (voidptr_set))
523 ++alias_stats.num_universal;
524 return true;
528 ++alias_stats.num_disambiguated;
530 /* The two alias sets are distinct and neither one is the
531 child of the other. Therefore, they cannot conflict. */
532 return 0;
535 /* Return 1 if the two specified alias sets will always conflict. */
538 alias_sets_must_conflict_p (alias_set_type set1, alias_set_type set2)
540 if (set1 == 0 || set2 == 0)
542 ++alias_stats.num_alias_zero;
543 return 1;
545 if (set1 == set2)
547 ++alias_stats.num_same_alias_set;
548 return 1;
551 return 0;
554 /* Return 1 if any MEM object of type T1 will always conflict (using the
555 dependency routines in this file) with any MEM object of type T2.
556 This is used when allocating temporary storage. If T1 and/or T2 are
557 NULL_TREE, it means we know nothing about the storage. */
560 objects_must_conflict_p (tree t1, tree t2)
562 alias_set_type set1, set2;
564 /* If neither has a type specified, we don't know if they'll conflict
565 because we may be using them to store objects of various types, for
566 example the argument and local variables areas of inlined functions. */
567 if (t1 == 0 && t2 == 0)
568 return 0;
570 /* If they are the same type, they must conflict. */
571 if (t1 == t2)
573 ++alias_stats.num_same_objects;
574 return 1;
576 /* Likewise if both are volatile. */
577 if (t1 != 0 && TYPE_VOLATILE (t1) && t2 != 0 && TYPE_VOLATILE (t2))
579 ++alias_stats.num_volatile;
580 return 1;
583 set1 = t1 ? get_alias_set (t1) : 0;
584 set2 = t2 ? get_alias_set (t2) : 0;
586 /* We can't use alias_sets_conflict_p because we must make sure
587 that every subtype of t1 will conflict with every subtype of
588 t2 for which a pair of subobjects of these respective subtypes
589 overlaps on the stack. */
590 return alias_sets_must_conflict_p (set1, set2);
593 /* Return the outermost parent of component present in the chain of
594 component references handled by get_inner_reference in T with the
595 following property:
596 - the component is non-addressable, or
597 - the parent has alias set zero,
598 or NULL_TREE if no such parent exists. In the former cases, the alias
599 set of this parent is the alias set that must be used for T itself. */
601 tree
602 component_uses_parent_alias_set_from (const_tree t)
604 const_tree found = NULL_TREE;
606 while (handled_component_p (t))
608 switch (TREE_CODE (t))
610 case COMPONENT_REF:
611 if (DECL_NONADDRESSABLE_P (TREE_OPERAND (t, 1)))
612 found = t;
613 break;
615 case ARRAY_REF:
616 case ARRAY_RANGE_REF:
617 if (TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t, 0))))
618 found = t;
619 break;
621 case REALPART_EXPR:
622 case IMAGPART_EXPR:
623 break;
625 case BIT_FIELD_REF:
626 case VIEW_CONVERT_EXPR:
627 /* Bitfields and casts are never addressable. */
628 found = t;
629 break;
631 default:
632 gcc_unreachable ();
635 if (get_alias_set (TREE_TYPE (TREE_OPERAND (t, 0))) == 0)
636 found = t;
638 t = TREE_OPERAND (t, 0);
641 if (found)
642 return TREE_OPERAND (found, 0);
644 return NULL_TREE;
648 /* Return whether the pointer-type T effective for aliasing may
649 access everything and thus the reference has to be assigned
650 alias-set zero. */
652 static bool
653 ref_all_alias_ptr_type_p (const_tree t)
655 return (TREE_CODE (TREE_TYPE (t)) == VOID_TYPE
656 || TYPE_REF_CAN_ALIAS_ALL (t));
659 /* Return the alias set for the memory pointed to by T, which may be
660 either a type or an expression. Return -1 if there is nothing
661 special about dereferencing T. */
663 static alias_set_type
664 get_deref_alias_set_1 (tree t)
666 /* All we care about is the type. */
667 if (! TYPE_P (t))
668 t = TREE_TYPE (t);
670 /* If we have an INDIRECT_REF via a void pointer, we don't
671 know anything about what that might alias. Likewise if the
672 pointer is marked that way. */
673 if (ref_all_alias_ptr_type_p (t))
674 return 0;
676 return -1;
679 /* Return the alias set for the memory pointed to by T, which may be
680 either a type or an expression. */
682 alias_set_type
683 get_deref_alias_set (tree t)
685 /* If we're not doing any alias analysis, just assume everything
686 aliases everything else. */
687 if (!flag_strict_aliasing)
688 return 0;
690 alias_set_type set = get_deref_alias_set_1 (t);
692 /* Fall back to the alias-set of the pointed-to type. */
693 if (set == -1)
695 if (! TYPE_P (t))
696 t = TREE_TYPE (t);
697 set = get_alias_set (TREE_TYPE (t));
700 return set;
703 /* Return the pointer-type relevant for TBAA purposes from the
704 memory reference tree *T or NULL_TREE in which case *T is
705 adjusted to point to the outermost component reference that
706 can be used for assigning an alias set. */
708 static tree
709 reference_alias_ptr_type_1 (tree *t)
711 tree inner;
713 /* Get the base object of the reference. */
714 inner = *t;
715 while (handled_component_p (inner))
717 /* If there is a VIEW_CONVERT_EXPR in the chain we cannot use
718 the type of any component references that wrap it to
719 determine the alias-set. */
720 if (TREE_CODE (inner) == VIEW_CONVERT_EXPR)
721 *t = TREE_OPERAND (inner, 0);
722 inner = TREE_OPERAND (inner, 0);
725 /* Handle pointer dereferences here, they can override the
726 alias-set. */
727 if (INDIRECT_REF_P (inner)
728 && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner, 0))))
729 return TREE_TYPE (TREE_OPERAND (inner, 0));
730 else if (TREE_CODE (inner) == TARGET_MEM_REF)
731 return TREE_TYPE (TMR_OFFSET (inner));
732 else if (TREE_CODE (inner) == MEM_REF
733 && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner, 1))))
734 return TREE_TYPE (TREE_OPERAND (inner, 1));
736 /* If the innermost reference is a MEM_REF that has a
737 conversion embedded treat it like a VIEW_CONVERT_EXPR above,
738 using the memory access type for determining the alias-set. */
739 if (TREE_CODE (inner) == MEM_REF
740 && (TYPE_MAIN_VARIANT (TREE_TYPE (inner))
741 != TYPE_MAIN_VARIANT
742 (TREE_TYPE (TREE_TYPE (TREE_OPERAND (inner, 1))))))
743 return TREE_TYPE (TREE_OPERAND (inner, 1));
745 /* Otherwise, pick up the outermost object that we could have
746 a pointer to. */
747 tree tem = component_uses_parent_alias_set_from (*t);
748 if (tem)
749 *t = tem;
751 return NULL_TREE;
754 /* Return the pointer-type relevant for TBAA purposes from the
755 gimple memory reference tree T. This is the type to be used for
756 the offset operand of MEM_REF or TARGET_MEM_REF replacements of T
757 and guarantees that get_alias_set will return the same alias
758 set for T and the replacement. */
760 tree
761 reference_alias_ptr_type (tree t)
763 tree ptype = reference_alias_ptr_type_1 (&t);
764 /* If there is a given pointer type for aliasing purposes, return it. */
765 if (ptype != NULL_TREE)
766 return ptype;
768 /* Otherwise build one from the outermost component reference we
769 may use. */
770 if (TREE_CODE (t) == MEM_REF
771 || TREE_CODE (t) == TARGET_MEM_REF)
772 return TREE_TYPE (TREE_OPERAND (t, 1));
773 else
774 return build_pointer_type (TYPE_MAIN_VARIANT (TREE_TYPE (t)));
777 /* Return whether the pointer-types T1 and T2 used to determine
778 two alias sets of two references will yield the same answer
779 from get_deref_alias_set. */
781 bool
782 alias_ptr_types_compatible_p (tree t1, tree t2)
784 if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
785 return true;
787 if (ref_all_alias_ptr_type_p (t1)
788 || ref_all_alias_ptr_type_p (t2))
789 return false;
791 return (TYPE_MAIN_VARIANT (TREE_TYPE (t1))
792 == TYPE_MAIN_VARIANT (TREE_TYPE (t2)));
795 /* Create emptry alias set entry. */
797 alias_set_entry *
798 init_alias_set_entry (alias_set_type set)
800 alias_set_entry *ase = ggc_alloc<alias_set_entry> ();
801 ase->alias_set = set;
802 ase->children = NULL;
803 ase->has_zero_child = false;
804 ase->is_pointer = false;
805 ase->has_pointer = false;
806 gcc_checking_assert (!get_alias_set_entry (set));
807 (*alias_sets)[set] = ase;
808 return ase;
811 /* Return the alias set for T, which may be either a type or an
812 expression. Call language-specific routine for help, if needed. */
814 alias_set_type
815 get_alias_set (tree t)
817 alias_set_type set;
819 /* If we're not doing any alias analysis, just assume everything
820 aliases everything else. Also return 0 if this or its type is
821 an error. */
822 if (! flag_strict_aliasing || t == error_mark_node
823 || (! TYPE_P (t)
824 && (TREE_TYPE (t) == 0 || TREE_TYPE (t) == error_mark_node)))
825 return 0;
827 /* We can be passed either an expression or a type. This and the
828 language-specific routine may make mutually-recursive calls to each other
829 to figure out what to do. At each juncture, we see if this is a tree
830 that the language may need to handle specially. First handle things that
831 aren't types. */
832 if (! TYPE_P (t))
834 /* Give the language a chance to do something with this tree
835 before we look at it. */
836 STRIP_NOPS (t);
837 set = lang_hooks.get_alias_set (t);
838 if (set != -1)
839 return set;
841 /* Get the alias pointer-type to use or the outermost object
842 that we could have a pointer to. */
843 tree ptype = reference_alias_ptr_type_1 (&t);
844 if (ptype != NULL)
845 return get_deref_alias_set (ptype);
847 /* If we've already determined the alias set for a decl, just return
848 it. This is necessary for C++ anonymous unions, whose component
849 variables don't look like union members (boo!). */
850 if (TREE_CODE (t) == VAR_DECL
851 && DECL_RTL_SET_P (t) && MEM_P (DECL_RTL (t)))
852 return MEM_ALIAS_SET (DECL_RTL (t));
854 /* Now all we care about is the type. */
855 t = TREE_TYPE (t);
858 /* Variant qualifiers don't affect the alias set, so get the main
859 variant. */
860 t = TYPE_MAIN_VARIANT (t);
862 /* Always use the canonical type as well. If this is a type that
863 requires structural comparisons to identify compatible types
864 use alias set zero. */
865 if (TYPE_STRUCTURAL_EQUALITY_P (t))
867 /* Allow the language to specify another alias set for this
868 type. */
869 set = lang_hooks.get_alias_set (t);
870 if (set != -1)
871 return set;
872 return 0;
875 t = TYPE_CANONICAL (t);
877 /* The canonical type should not require structural equality checks. */
878 gcc_checking_assert (!TYPE_STRUCTURAL_EQUALITY_P (t));
880 /* If this is a type with a known alias set, return it. */
881 if (TYPE_ALIAS_SET_KNOWN_P (t))
882 return TYPE_ALIAS_SET (t);
884 /* We don't want to set TYPE_ALIAS_SET for incomplete types. */
885 if (!COMPLETE_TYPE_P (t))
887 /* For arrays with unknown size the conservative answer is the
888 alias set of the element type. */
889 if (TREE_CODE (t) == ARRAY_TYPE)
890 return get_alias_set (TREE_TYPE (t));
892 /* But return zero as a conservative answer for incomplete types. */
893 return 0;
896 /* See if the language has special handling for this type. */
897 set = lang_hooks.get_alias_set (t);
898 if (set != -1)
899 return set;
901 /* There are no objects of FUNCTION_TYPE, so there's no point in
902 using up an alias set for them. (There are, of course, pointers
903 and references to functions, but that's different.) */
904 else if (TREE_CODE (t) == FUNCTION_TYPE || TREE_CODE (t) == METHOD_TYPE)
905 set = 0;
907 /* Unless the language specifies otherwise, let vector types alias
908 their components. This avoids some nasty type punning issues in
909 normal usage. And indeed lets vectors be treated more like an
910 array slice. */
911 else if (TREE_CODE (t) == VECTOR_TYPE)
912 set = get_alias_set (TREE_TYPE (t));
914 /* Unless the language specifies otherwise, treat array types the
915 same as their components. This avoids the asymmetry we get
916 through recording the components. Consider accessing a
917 character(kind=1) through a reference to a character(kind=1)[1:1].
918 Or consider if we want to assign integer(kind=4)[0:D.1387] and
919 integer(kind=4)[4] the same alias set or not.
920 Just be pragmatic here and make sure the array and its element
921 type get the same alias set assigned. */
922 else if (TREE_CODE (t) == ARRAY_TYPE && !TYPE_NONALIASED_COMPONENT (t))
923 set = get_alias_set (TREE_TYPE (t));
925 /* From the former common C and C++ langhook implementation:
927 Unfortunately, there is no canonical form of a pointer type.
928 In particular, if we have `typedef int I', then `int *', and
929 `I *' are different types. So, we have to pick a canonical
930 representative. We do this below.
932 Technically, this approach is actually more conservative that
933 it needs to be. In particular, `const int *' and `int *'
934 should be in different alias sets, according to the C and C++
935 standard, since their types are not the same, and so,
936 technically, an `int **' and `const int **' cannot point at
937 the same thing.
939 But, the standard is wrong. In particular, this code is
940 legal C++:
942 int *ip;
943 int **ipp = &ip;
944 const int* const* cipp = ipp;
945 And, it doesn't make sense for that to be legal unless you
946 can dereference IPP and CIPP. So, we ignore cv-qualifiers on
947 the pointed-to types. This issue has been reported to the
948 C++ committee.
950 For this reason go to canonical type of the unqalified pointer type.
951 Until GCC 6 this code set all pointers sets to have alias set of
952 ptr_type_node but that is a bad idea, because it prevents disabiguations
953 in between pointers. For Firefox this accounts about 20% of all
954 disambiguations in the program. */
955 else if (POINTER_TYPE_P (t) && t != ptr_type_node && !in_lto_p)
957 tree p;
958 auto_vec <bool, 8> reference;
960 /* Unnest all pointers and references.
961 We also want to make pointer to array equivalent to pointer to its
962 element. So skip all array types, too. */
963 for (p = t; POINTER_TYPE_P (p)
964 || (TREE_CODE (p) == ARRAY_TYPE && !TYPE_NONALIASED_COMPONENT (p));
965 p = TREE_TYPE (p))
967 if (TREE_CODE (p) == REFERENCE_TYPE)
968 reference.safe_push (true);
969 if (TREE_CODE (p) == POINTER_TYPE)
970 reference.safe_push (false);
972 p = TYPE_MAIN_VARIANT (p);
974 /* Make void * compatible with char * and also void **.
975 Programs are commonly violating TBAA by this.
977 We also make void * to conflict with every pointer
978 (see record_component_aliases) and thus it is safe it to use it for
979 pointers to types with TYPE_STRUCTURAL_EQUALITY_P. */
980 if (TREE_CODE (p) == VOID_TYPE || TYPE_STRUCTURAL_EQUALITY_P (p))
981 set = get_alias_set (ptr_type_node);
982 else
984 /* Rebuild pointer type from starting from canonical types using
985 unqualified pointers and references only. This way all such
986 pointers will have the same alias set and will conflict with
987 each other.
989 Most of time we already have pointers or references of a given type.
990 If not we build new one just to be sure that if someone later
991 (probably only middle-end can, as we should assign all alias
992 classes only after finishing translation unit) builds the pointer
993 type, the canonical type will match. */
994 p = TYPE_CANONICAL (p);
995 while (!reference.is_empty ())
997 if (reference.pop ())
998 p = build_reference_type (p);
999 else
1000 p = build_pointer_type (p);
1001 p = TYPE_CANONICAL (TYPE_MAIN_VARIANT (p));
1003 gcc_checking_assert (TYPE_CANONICAL (p) == p);
1005 /* Assign the alias set to both p and t.
1006 We can not call get_alias_set (p) here as that would trigger
1007 infinite recursion when p == t. In other cases it would just
1008 trigger unnecesary legwork of rebuilding the pointer again. */
1009 if (TYPE_ALIAS_SET_KNOWN_P (p))
1010 set = TYPE_ALIAS_SET (p);
1011 else
1013 set = new_alias_set ();
1014 TYPE_ALIAS_SET (p) = set;
1018 /* In LTO the rules above needs to be part of canonical type machinery.
1019 For now just punt. */
1020 else if (POINTER_TYPE_P (t)
1021 && t != TYPE_CANONICAL (ptr_type_node) && in_lto_p)
1022 set = get_alias_set (TYPE_CANONICAL (ptr_type_node));
1024 /* Otherwise make a new alias set for this type. */
1025 else
1027 /* Each canonical type gets its own alias set, so canonical types
1028 shouldn't form a tree. It doesn't really matter for types
1029 we handle specially above, so only check it where it possibly
1030 would result in a bogus alias set. */
1031 gcc_checking_assert (TYPE_CANONICAL (t) == t);
1033 set = new_alias_set ();
1036 TYPE_ALIAS_SET (t) = set;
1038 /* If this is an aggregate type or a complex type, we must record any
1039 component aliasing information. */
1040 if (AGGREGATE_TYPE_P (t) || TREE_CODE (t) == COMPLEX_TYPE)
1041 record_component_aliases (t);
1043 /* We treat pointer types specially in alias_set_subset_of. */
1044 if (POINTER_TYPE_P (t) && set)
1046 alias_set_entry *ase = get_alias_set_entry (set);
1047 if (!ase)
1048 ase = init_alias_set_entry (set);
1049 ase->is_pointer = true;
1050 ase->has_pointer = true;
1053 return set;
1056 /* Return a brand-new alias set. */
1058 alias_set_type
1059 new_alias_set (void)
1061 if (flag_strict_aliasing)
1063 if (alias_sets == 0)
1064 vec_safe_push (alias_sets, (alias_set_entry *) NULL);
1065 vec_safe_push (alias_sets, (alias_set_entry *) NULL);
1066 return alias_sets->length () - 1;
1068 else
1069 return 0;
1072 /* Indicate that things in SUBSET can alias things in SUPERSET, but that
1073 not everything that aliases SUPERSET also aliases SUBSET. For example,
1074 in C, a store to an `int' can alias a load of a structure containing an
1075 `int', and vice versa. But it can't alias a load of a 'double' member
1076 of the same structure. Here, the structure would be the SUPERSET and
1077 `int' the SUBSET. This relationship is also described in the comment at
1078 the beginning of this file.
1080 This function should be called only once per SUPERSET/SUBSET pair.
1082 It is illegal for SUPERSET to be zero; everything is implicitly a
1083 subset of alias set zero. */
1085 void
1086 record_alias_subset (alias_set_type superset, alias_set_type subset)
1088 alias_set_entry *superset_entry;
1089 alias_set_entry *subset_entry;
1091 /* It is possible in complex type situations for both sets to be the same,
1092 in which case we can ignore this operation. */
1093 if (superset == subset)
1094 return;
1096 gcc_assert (superset);
1098 superset_entry = get_alias_set_entry (superset);
1099 if (superset_entry == 0)
1101 /* Create an entry for the SUPERSET, so that we have a place to
1102 attach the SUBSET. */
1103 superset_entry = init_alias_set_entry (superset);
1106 if (subset == 0)
1107 superset_entry->has_zero_child = 1;
1108 else
1110 subset_entry = get_alias_set_entry (subset);
1111 if (!superset_entry->children)
1112 superset_entry->children
1113 = hash_map<alias_set_hash, int>::create_ggc (64);
1114 /* If there is an entry for the subset, enter all of its children
1115 (if they are not already present) as children of the SUPERSET. */
1116 if (subset_entry)
1118 if (subset_entry->has_zero_child)
1119 superset_entry->has_zero_child = true;
1120 if (subset_entry->has_pointer)
1121 superset_entry->has_pointer = true;
1123 if (subset_entry->children)
1125 hash_map<alias_set_hash, int>::iterator iter
1126 = subset_entry->children->begin ();
1127 for (; iter != subset_entry->children->end (); ++iter)
1128 superset_entry->children->put ((*iter).first, (*iter).second);
1132 /* Enter the SUBSET itself as a child of the SUPERSET. */
1133 superset_entry->children->put (subset, 0);
1137 /* Record that component types of TYPE, if any, are part of that type for
1138 aliasing purposes. For record types, we only record component types
1139 for fields that are not marked non-addressable. For array types, we
1140 only record the component type if it is not marked non-aliased. */
1142 void
1143 record_component_aliases (tree type)
1145 alias_set_type superset = get_alias_set (type);
1146 tree field;
1148 if (superset == 0)
1149 return;
1151 switch (TREE_CODE (type))
1153 case RECORD_TYPE:
1154 case UNION_TYPE:
1155 case QUAL_UNION_TYPE:
1156 for (field = TYPE_FIELDS (type); field != 0; field = DECL_CHAIN (field))
1157 if (TREE_CODE (field) == FIELD_DECL && !DECL_NONADDRESSABLE_P (field))
1158 record_alias_subset (superset, get_alias_set (TREE_TYPE (field)));
1159 break;
1161 case COMPLEX_TYPE:
1162 record_alias_subset (superset, get_alias_set (TREE_TYPE (type)));
1163 break;
1165 /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their
1166 element type. */
1168 default:
1169 break;
1173 /* Allocate an alias set for use in storing and reading from the varargs
1174 spill area. */
1176 static GTY(()) alias_set_type varargs_set = -1;
1178 alias_set_type
1179 get_varargs_alias_set (void)
1181 #if 1
1182 /* We now lower VA_ARG_EXPR, and there's currently no way to attach the
1183 varargs alias set to an INDIRECT_REF (FIXME!), so we can't
1184 consistently use the varargs alias set for loads from the varargs
1185 area. So don't use it anywhere. */
1186 return 0;
1187 #else
1188 if (varargs_set == -1)
1189 varargs_set = new_alias_set ();
1191 return varargs_set;
1192 #endif
1195 /* Likewise, but used for the fixed portions of the frame, e.g., register
1196 save areas. */
1198 static GTY(()) alias_set_type frame_set = -1;
1200 alias_set_type
1201 get_frame_alias_set (void)
1203 if (frame_set == -1)
1204 frame_set = new_alias_set ();
1206 return frame_set;
1209 /* Create a new, unique base with id ID. */
1211 static rtx
1212 unique_base_value (HOST_WIDE_INT id)
1214 return gen_rtx_ADDRESS (Pmode, id);
1217 /* Return true if accesses based on any other base value cannot alias
1218 those based on X. */
1220 static bool
1221 unique_base_value_p (rtx x)
1223 return GET_CODE (x) == ADDRESS && GET_MODE (x) == Pmode;
1226 /* Return true if X is known to be a base value. */
1228 static bool
1229 known_base_value_p (rtx x)
1231 switch (GET_CODE (x))
1233 case LABEL_REF:
1234 case SYMBOL_REF:
1235 return true;
1237 case ADDRESS:
1238 /* Arguments may or may not be bases; we don't know for sure. */
1239 return GET_MODE (x) != VOIDmode;
1241 default:
1242 return false;
1246 /* Inside SRC, the source of a SET, find a base address. */
1248 static rtx
1249 find_base_value (rtx src)
1251 unsigned int regno;
1253 #if defined (FIND_BASE_TERM)
1254 /* Try machine-dependent ways to find the base term. */
1255 src = FIND_BASE_TERM (src);
1256 #endif
1258 switch (GET_CODE (src))
1260 case SYMBOL_REF:
1261 case LABEL_REF:
1262 return src;
1264 case REG:
1265 regno = REGNO (src);
1266 /* At the start of a function, argument registers have known base
1267 values which may be lost later. Returning an ADDRESS
1268 expression here allows optimization based on argument values
1269 even when the argument registers are used for other purposes. */
1270 if (regno < FIRST_PSEUDO_REGISTER && copying_arguments)
1271 return new_reg_base_value[regno];
1273 /* If a pseudo has a known base value, return it. Do not do this
1274 for non-fixed hard regs since it can result in a circular
1275 dependency chain for registers which have values at function entry.
1277 The test above is not sufficient because the scheduler may move
1278 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
1279 if ((regno >= FIRST_PSEUDO_REGISTER || fixed_regs[regno])
1280 && regno < vec_safe_length (reg_base_value))
1282 /* If we're inside init_alias_analysis, use new_reg_base_value
1283 to reduce the number of relaxation iterations. */
1284 if (new_reg_base_value && new_reg_base_value[regno]
1285 && DF_REG_DEF_COUNT (regno) == 1)
1286 return new_reg_base_value[regno];
1288 if ((*reg_base_value)[regno])
1289 return (*reg_base_value)[regno];
1292 return 0;
1294 case MEM:
1295 /* Check for an argument passed in memory. Only record in the
1296 copying-arguments block; it is too hard to track changes
1297 otherwise. */
1298 if (copying_arguments
1299 && (XEXP (src, 0) == arg_pointer_rtx
1300 || (GET_CODE (XEXP (src, 0)) == PLUS
1301 && XEXP (XEXP (src, 0), 0) == arg_pointer_rtx)))
1302 return arg_base_value;
1303 return 0;
1305 case CONST:
1306 src = XEXP (src, 0);
1307 if (GET_CODE (src) != PLUS && GET_CODE (src) != MINUS)
1308 break;
1310 /* ... fall through ... */
1312 case PLUS:
1313 case MINUS:
1315 rtx temp, src_0 = XEXP (src, 0), src_1 = XEXP (src, 1);
1317 /* If either operand is a REG that is a known pointer, then it
1318 is the base. */
1319 if (REG_P (src_0) && REG_POINTER (src_0))
1320 return find_base_value (src_0);
1321 if (REG_P (src_1) && REG_POINTER (src_1))
1322 return find_base_value (src_1);
1324 /* If either operand is a REG, then see if we already have
1325 a known value for it. */
1326 if (REG_P (src_0))
1328 temp = find_base_value (src_0);
1329 if (temp != 0)
1330 src_0 = temp;
1333 if (REG_P (src_1))
1335 temp = find_base_value (src_1);
1336 if (temp!= 0)
1337 src_1 = temp;
1340 /* If either base is named object or a special address
1341 (like an argument or stack reference), then use it for the
1342 base term. */
1343 if (src_0 != 0 && known_base_value_p (src_0))
1344 return src_0;
1346 if (src_1 != 0 && known_base_value_p (src_1))
1347 return src_1;
1349 /* Guess which operand is the base address:
1350 If either operand is a symbol, then it is the base. If
1351 either operand is a CONST_INT, then the other is the base. */
1352 if (CONST_INT_P (src_1) || CONSTANT_P (src_0))
1353 return find_base_value (src_0);
1354 else if (CONST_INT_P (src_0) || CONSTANT_P (src_1))
1355 return find_base_value (src_1);
1357 return 0;
1360 case LO_SUM:
1361 /* The standard form is (lo_sum reg sym) so look only at the
1362 second operand. */
1363 return find_base_value (XEXP (src, 1));
1365 case AND:
1366 /* If the second operand is constant set the base
1367 address to the first operand. */
1368 if (CONST_INT_P (XEXP (src, 1)) && INTVAL (XEXP (src, 1)) != 0)
1369 return find_base_value (XEXP (src, 0));
1370 return 0;
1372 case TRUNCATE:
1373 /* As we do not know which address space the pointer is referring to, we can
1374 handle this only if the target does not support different pointer or
1375 address modes depending on the address space. */
1376 if (!target_default_pointer_address_modes_p ())
1377 break;
1378 if (GET_MODE_SIZE (GET_MODE (src)) < GET_MODE_SIZE (Pmode))
1379 break;
1380 /* Fall through. */
1381 case HIGH:
1382 case PRE_INC:
1383 case PRE_DEC:
1384 case POST_INC:
1385 case POST_DEC:
1386 case PRE_MODIFY:
1387 case POST_MODIFY:
1388 return find_base_value (XEXP (src, 0));
1390 case ZERO_EXTEND:
1391 case SIGN_EXTEND: /* used for NT/Alpha pointers */
1392 /* As we do not know which address space the pointer is referring to, we can
1393 handle this only if the target does not support different pointer or
1394 address modes depending on the address space. */
1395 if (!target_default_pointer_address_modes_p ())
1396 break;
1399 rtx temp = find_base_value (XEXP (src, 0));
1401 if (temp != 0 && CONSTANT_P (temp))
1402 temp = convert_memory_address (Pmode, temp);
1404 return temp;
1407 default:
1408 break;
1411 return 0;
1414 /* Called from init_alias_analysis indirectly through note_stores,
1415 or directly if DEST is a register with a REG_NOALIAS note attached.
1416 SET is null in the latter case. */
1418 /* While scanning insns to find base values, reg_seen[N] is nonzero if
1419 register N has been set in this function. */
1420 static sbitmap reg_seen;
1422 static void
1423 record_set (rtx dest, const_rtx set, void *data ATTRIBUTE_UNUSED)
1425 unsigned regno;
1426 rtx src;
1427 int n;
1429 if (!REG_P (dest))
1430 return;
1432 regno = REGNO (dest);
1434 gcc_checking_assert (regno < reg_base_value->length ());
1436 n = REG_NREGS (dest);
1437 if (n != 1)
1439 while (--n >= 0)
1441 bitmap_set_bit (reg_seen, regno + n);
1442 new_reg_base_value[regno + n] = 0;
1444 return;
1447 if (set)
1449 /* A CLOBBER wipes out any old value but does not prevent a previously
1450 unset register from acquiring a base address (i.e. reg_seen is not
1451 set). */
1452 if (GET_CODE (set) == CLOBBER)
1454 new_reg_base_value[regno] = 0;
1455 return;
1457 src = SET_SRC (set);
1459 else
1461 /* There's a REG_NOALIAS note against DEST. */
1462 if (bitmap_bit_p (reg_seen, regno))
1464 new_reg_base_value[regno] = 0;
1465 return;
1467 bitmap_set_bit (reg_seen, regno);
1468 new_reg_base_value[regno] = unique_base_value (unique_id++);
1469 return;
1472 /* If this is not the first set of REGNO, see whether the new value
1473 is related to the old one. There are two cases of interest:
1475 (1) The register might be assigned an entirely new value
1476 that has the same base term as the original set.
1478 (2) The set might be a simple self-modification that
1479 cannot change REGNO's base value.
1481 If neither case holds, reject the original base value as invalid.
1482 Note that the following situation is not detected:
1484 extern int x, y; int *p = &x; p += (&y-&x);
1486 ANSI C does not allow computing the difference of addresses
1487 of distinct top level objects. */
1488 if (new_reg_base_value[regno] != 0
1489 && find_base_value (src) != new_reg_base_value[regno])
1490 switch (GET_CODE (src))
1492 case LO_SUM:
1493 case MINUS:
1494 if (XEXP (src, 0) != dest && XEXP (src, 1) != dest)
1495 new_reg_base_value[regno] = 0;
1496 break;
1497 case PLUS:
1498 /* If the value we add in the PLUS is also a valid base value,
1499 this might be the actual base value, and the original value
1500 an index. */
1502 rtx other = NULL_RTX;
1504 if (XEXP (src, 0) == dest)
1505 other = XEXP (src, 1);
1506 else if (XEXP (src, 1) == dest)
1507 other = XEXP (src, 0);
1509 if (! other || find_base_value (other))
1510 new_reg_base_value[regno] = 0;
1511 break;
1513 case AND:
1514 if (XEXP (src, 0) != dest || !CONST_INT_P (XEXP (src, 1)))
1515 new_reg_base_value[regno] = 0;
1516 break;
1517 default:
1518 new_reg_base_value[regno] = 0;
1519 break;
1521 /* If this is the first set of a register, record the value. */
1522 else if ((regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
1523 && ! bitmap_bit_p (reg_seen, regno) && new_reg_base_value[regno] == 0)
1524 new_reg_base_value[regno] = find_base_value (src);
1526 bitmap_set_bit (reg_seen, regno);
1529 /* Return REG_BASE_VALUE for REGNO. Selective scheduler uses this to avoid
1530 using hard registers with non-null REG_BASE_VALUE for renaming. */
1532 get_reg_base_value (unsigned int regno)
1534 return (*reg_base_value)[regno];
1537 /* If a value is known for REGNO, return it. */
1540 get_reg_known_value (unsigned int regno)
1542 if (regno >= FIRST_PSEUDO_REGISTER)
1544 regno -= FIRST_PSEUDO_REGISTER;
1545 if (regno < vec_safe_length (reg_known_value))
1546 return (*reg_known_value)[regno];
1548 return NULL;
1551 /* Set it. */
1553 static void
1554 set_reg_known_value (unsigned int regno, rtx val)
1556 if (regno >= FIRST_PSEUDO_REGISTER)
1558 regno -= FIRST_PSEUDO_REGISTER;
1559 if (regno < vec_safe_length (reg_known_value))
1560 (*reg_known_value)[regno] = val;
1564 /* Similarly for reg_known_equiv_p. */
1566 bool
1567 get_reg_known_equiv_p (unsigned int regno)
1569 if (regno >= FIRST_PSEUDO_REGISTER)
1571 regno -= FIRST_PSEUDO_REGISTER;
1572 if (regno < vec_safe_length (reg_known_value))
1573 return bitmap_bit_p (reg_known_equiv_p, regno);
1575 return false;
1578 static void
1579 set_reg_known_equiv_p (unsigned int regno, bool val)
1581 if (regno >= FIRST_PSEUDO_REGISTER)
1583 regno -= FIRST_PSEUDO_REGISTER;
1584 if (regno < vec_safe_length (reg_known_value))
1586 if (val)
1587 bitmap_set_bit (reg_known_equiv_p, regno);
1588 else
1589 bitmap_clear_bit (reg_known_equiv_p, regno);
1595 /* Returns a canonical version of X, from the point of view alias
1596 analysis. (For example, if X is a MEM whose address is a register,
1597 and the register has a known value (say a SYMBOL_REF), then a MEM
1598 whose address is the SYMBOL_REF is returned.) */
1601 canon_rtx (rtx x)
1603 /* Recursively look for equivalences. */
1604 if (REG_P (x) && REGNO (x) >= FIRST_PSEUDO_REGISTER)
1606 rtx t = get_reg_known_value (REGNO (x));
1607 if (t == x)
1608 return x;
1609 if (t)
1610 return canon_rtx (t);
1613 if (GET_CODE (x) == PLUS)
1615 rtx x0 = canon_rtx (XEXP (x, 0));
1616 rtx x1 = canon_rtx (XEXP (x, 1));
1618 if (x0 != XEXP (x, 0) || x1 != XEXP (x, 1))
1620 if (CONST_INT_P (x0))
1621 return plus_constant (GET_MODE (x), x1, INTVAL (x0));
1622 else if (CONST_INT_P (x1))
1623 return plus_constant (GET_MODE (x), x0, INTVAL (x1));
1624 return gen_rtx_PLUS (GET_MODE (x), x0, x1);
1628 /* This gives us much better alias analysis when called from
1629 the loop optimizer. Note we want to leave the original
1630 MEM alone, but need to return the canonicalized MEM with
1631 all the flags with their original values. */
1632 else if (MEM_P (x))
1633 x = replace_equiv_address_nv (x, canon_rtx (XEXP (x, 0)));
1635 return x;
1638 /* Return 1 if X and Y are identical-looking rtx's.
1639 Expect that X and Y has been already canonicalized.
1641 We use the data in reg_known_value above to see if two registers with
1642 different numbers are, in fact, equivalent. */
1644 static int
1645 rtx_equal_for_memref_p (const_rtx x, const_rtx y)
1647 int i;
1648 int j;
1649 enum rtx_code code;
1650 const char *fmt;
1652 if (x == 0 && y == 0)
1653 return 1;
1654 if (x == 0 || y == 0)
1655 return 0;
1657 if (x == y)
1658 return 1;
1660 code = GET_CODE (x);
1661 /* Rtx's of different codes cannot be equal. */
1662 if (code != GET_CODE (y))
1663 return 0;
1665 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1666 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1668 if (GET_MODE (x) != GET_MODE (y))
1669 return 0;
1671 /* Some RTL can be compared without a recursive examination. */
1672 switch (code)
1674 case REG:
1675 return REGNO (x) == REGNO (y);
1677 case LABEL_REF:
1678 return LABEL_REF_LABEL (x) == LABEL_REF_LABEL (y);
1680 case SYMBOL_REF:
1681 return XSTR (x, 0) == XSTR (y, 0);
1683 case ENTRY_VALUE:
1684 /* This is magic, don't go through canonicalization et al. */
1685 return rtx_equal_p (ENTRY_VALUE_EXP (x), ENTRY_VALUE_EXP (y));
1687 case VALUE:
1688 CASE_CONST_UNIQUE:
1689 /* Pointer equality guarantees equality for these nodes. */
1690 return 0;
1692 default:
1693 break;
1696 /* canon_rtx knows how to handle plus. No need to canonicalize. */
1697 if (code == PLUS)
1698 return ((rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0))
1699 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1)))
1700 || (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 1))
1701 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 0))));
1702 /* For commutative operations, the RTX match if the operand match in any
1703 order. Also handle the simple binary and unary cases without a loop. */
1704 if (COMMUTATIVE_P (x))
1706 rtx xop0 = canon_rtx (XEXP (x, 0));
1707 rtx yop0 = canon_rtx (XEXP (y, 0));
1708 rtx yop1 = canon_rtx (XEXP (y, 1));
1710 return ((rtx_equal_for_memref_p (xop0, yop0)
1711 && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)), yop1))
1712 || (rtx_equal_for_memref_p (xop0, yop1)
1713 && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)), yop0)));
1715 else if (NON_COMMUTATIVE_P (x))
1717 return (rtx_equal_for_memref_p (canon_rtx (XEXP (x, 0)),
1718 canon_rtx (XEXP (y, 0)))
1719 && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)),
1720 canon_rtx (XEXP (y, 1))));
1722 else if (UNARY_P (x))
1723 return rtx_equal_for_memref_p (canon_rtx (XEXP (x, 0)),
1724 canon_rtx (XEXP (y, 0)));
1726 /* Compare the elements. If any pair of corresponding elements
1727 fail to match, return 0 for the whole things.
1729 Limit cases to types which actually appear in addresses. */
1731 fmt = GET_RTX_FORMAT (code);
1732 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1734 switch (fmt[i])
1736 case 'i':
1737 if (XINT (x, i) != XINT (y, i))
1738 return 0;
1739 break;
1741 case 'E':
1742 /* Two vectors must have the same length. */
1743 if (XVECLEN (x, i) != XVECLEN (y, i))
1744 return 0;
1746 /* And the corresponding elements must match. */
1747 for (j = 0; j < XVECLEN (x, i); j++)
1748 if (rtx_equal_for_memref_p (canon_rtx (XVECEXP (x, i, j)),
1749 canon_rtx (XVECEXP (y, i, j))) == 0)
1750 return 0;
1751 break;
1753 case 'e':
1754 if (rtx_equal_for_memref_p (canon_rtx (XEXP (x, i)),
1755 canon_rtx (XEXP (y, i))) == 0)
1756 return 0;
1757 break;
1759 /* This can happen for asm operands. */
1760 case 's':
1761 if (strcmp (XSTR (x, i), XSTR (y, i)))
1762 return 0;
1763 break;
1765 /* This can happen for an asm which clobbers memory. */
1766 case '0':
1767 break;
1769 /* It is believed that rtx's at this level will never
1770 contain anything but integers and other rtx's,
1771 except for within LABEL_REFs and SYMBOL_REFs. */
1772 default:
1773 gcc_unreachable ();
1776 return 1;
1779 static rtx
1780 find_base_term (rtx x)
1782 cselib_val *val;
1783 struct elt_loc_list *l, *f;
1784 rtx ret;
1786 #if defined (FIND_BASE_TERM)
1787 /* Try machine-dependent ways to find the base term. */
1788 x = FIND_BASE_TERM (x);
1789 #endif
1791 switch (GET_CODE (x))
1793 case REG:
1794 return REG_BASE_VALUE (x);
1796 case TRUNCATE:
1797 /* As we do not know which address space the pointer is referring to, we can
1798 handle this only if the target does not support different pointer or
1799 address modes depending on the address space. */
1800 if (!target_default_pointer_address_modes_p ())
1801 return 0;
1802 if (GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (Pmode))
1803 return 0;
1804 /* Fall through. */
1805 case HIGH:
1806 case PRE_INC:
1807 case PRE_DEC:
1808 case POST_INC:
1809 case POST_DEC:
1810 case PRE_MODIFY:
1811 case POST_MODIFY:
1812 return find_base_term (XEXP (x, 0));
1814 case ZERO_EXTEND:
1815 case SIGN_EXTEND: /* Used for Alpha/NT pointers */
1816 /* As we do not know which address space the pointer is referring to, we can
1817 handle this only if the target does not support different pointer or
1818 address modes depending on the address space. */
1819 if (!target_default_pointer_address_modes_p ())
1820 return 0;
1823 rtx temp = find_base_term (XEXP (x, 0));
1825 if (temp != 0 && CONSTANT_P (temp))
1826 temp = convert_memory_address (Pmode, temp);
1828 return temp;
1831 case VALUE:
1832 val = CSELIB_VAL_PTR (x);
1833 ret = NULL_RTX;
1835 if (!val)
1836 return ret;
1838 if (cselib_sp_based_value_p (val))
1839 return static_reg_base_value[STACK_POINTER_REGNUM];
1841 f = val->locs;
1842 /* Temporarily reset val->locs to avoid infinite recursion. */
1843 val->locs = NULL;
1845 for (l = f; l; l = l->next)
1846 if (GET_CODE (l->loc) == VALUE
1847 && CSELIB_VAL_PTR (l->loc)->locs
1848 && !CSELIB_VAL_PTR (l->loc)->locs->next
1849 && CSELIB_VAL_PTR (l->loc)->locs->loc == x)
1850 continue;
1851 else if ((ret = find_base_term (l->loc)) != 0)
1852 break;
1854 val->locs = f;
1855 return ret;
1857 case LO_SUM:
1858 /* The standard form is (lo_sum reg sym) so look only at the
1859 second operand. */
1860 return find_base_term (XEXP (x, 1));
1862 case CONST:
1863 x = XEXP (x, 0);
1864 if (GET_CODE (x) != PLUS && GET_CODE (x) != MINUS)
1865 return 0;
1866 /* Fall through. */
1867 case PLUS:
1868 case MINUS:
1870 rtx tmp1 = XEXP (x, 0);
1871 rtx tmp2 = XEXP (x, 1);
1873 /* This is a little bit tricky since we have to determine which of
1874 the two operands represents the real base address. Otherwise this
1875 routine may return the index register instead of the base register.
1877 That may cause us to believe no aliasing was possible, when in
1878 fact aliasing is possible.
1880 We use a few simple tests to guess the base register. Additional
1881 tests can certainly be added. For example, if one of the operands
1882 is a shift or multiply, then it must be the index register and the
1883 other operand is the base register. */
1885 if (tmp1 == pic_offset_table_rtx && CONSTANT_P (tmp2))
1886 return find_base_term (tmp2);
1888 /* If either operand is known to be a pointer, then prefer it
1889 to determine the base term. */
1890 if (REG_P (tmp1) && REG_POINTER (tmp1))
1892 else if (REG_P (tmp2) && REG_POINTER (tmp2))
1893 std::swap (tmp1, tmp2);
1894 /* If second argument is constant which has base term, prefer it
1895 over variable tmp1. See PR64025. */
1896 else if (CONSTANT_P (tmp2) && !CONST_INT_P (tmp2))
1897 std::swap (tmp1, tmp2);
1899 /* Go ahead and find the base term for both operands. If either base
1900 term is from a pointer or is a named object or a special address
1901 (like an argument or stack reference), then use it for the
1902 base term. */
1903 rtx base = find_base_term (tmp1);
1904 if (base != NULL_RTX
1905 && ((REG_P (tmp1) && REG_POINTER (tmp1))
1906 || known_base_value_p (base)))
1907 return base;
1908 base = find_base_term (tmp2);
1909 if (base != NULL_RTX
1910 && ((REG_P (tmp2) && REG_POINTER (tmp2))
1911 || known_base_value_p (base)))
1912 return base;
1914 /* We could not determine which of the two operands was the
1915 base register and which was the index. So we can determine
1916 nothing from the base alias check. */
1917 return 0;
1920 case AND:
1921 if (CONST_INT_P (XEXP (x, 1)) && INTVAL (XEXP (x, 1)) != 0)
1922 return find_base_term (XEXP (x, 0));
1923 return 0;
1925 case SYMBOL_REF:
1926 case LABEL_REF:
1927 return x;
1929 default:
1930 return 0;
1934 /* Return true if accesses to address X may alias accesses based
1935 on the stack pointer. */
1937 bool
1938 may_be_sp_based_p (rtx x)
1940 rtx base = find_base_term (x);
1941 return !base || base == static_reg_base_value[STACK_POINTER_REGNUM];
1944 /* Return 0 if the addresses X and Y are known to point to different
1945 objects, 1 if they might be pointers to the same object. */
1947 static int
1948 base_alias_check (rtx x, rtx x_base, rtx y, rtx y_base,
1949 machine_mode x_mode, machine_mode y_mode)
1951 /* If the address itself has no known base see if a known equivalent
1952 value has one. If either address still has no known base, nothing
1953 is known about aliasing. */
1954 if (x_base == 0)
1956 rtx x_c;
1958 if (! flag_expensive_optimizations || (x_c = canon_rtx (x)) == x)
1959 return 1;
1961 x_base = find_base_term (x_c);
1962 if (x_base == 0)
1963 return 1;
1966 if (y_base == 0)
1968 rtx y_c;
1969 if (! flag_expensive_optimizations || (y_c = canon_rtx (y)) == y)
1970 return 1;
1972 y_base = find_base_term (y_c);
1973 if (y_base == 0)
1974 return 1;
1977 /* If the base addresses are equal nothing is known about aliasing. */
1978 if (rtx_equal_p (x_base, y_base))
1979 return 1;
1981 /* The base addresses are different expressions. If they are not accessed
1982 via AND, there is no conflict. We can bring knowledge of object
1983 alignment into play here. For example, on alpha, "char a, b;" can
1984 alias one another, though "char a; long b;" cannot. AND addesses may
1985 implicitly alias surrounding objects; i.e. unaligned access in DImode
1986 via AND address can alias all surrounding object types except those
1987 with aligment 8 or higher. */
1988 if (GET_CODE (x) == AND && GET_CODE (y) == AND)
1989 return 1;
1990 if (GET_CODE (x) == AND
1991 && (!CONST_INT_P (XEXP (x, 1))
1992 || (int) GET_MODE_UNIT_SIZE (y_mode) < -INTVAL (XEXP (x, 1))))
1993 return 1;
1994 if (GET_CODE (y) == AND
1995 && (!CONST_INT_P (XEXP (y, 1))
1996 || (int) GET_MODE_UNIT_SIZE (x_mode) < -INTVAL (XEXP (y, 1))))
1997 return 1;
1999 /* Differing symbols not accessed via AND never alias. */
2000 if (GET_CODE (x_base) != ADDRESS && GET_CODE (y_base) != ADDRESS)
2001 return 0;
2003 if (unique_base_value_p (x_base) || unique_base_value_p (y_base))
2004 return 0;
2006 return 1;
2009 /* Return TRUE if EXPR refers to a VALUE whose uid is greater than
2010 that of V. */
2012 static bool
2013 refs_newer_value_p (const_rtx expr, rtx v)
2015 int minuid = CSELIB_VAL_PTR (v)->uid;
2016 subrtx_iterator::array_type array;
2017 FOR_EACH_SUBRTX (iter, array, expr, NONCONST)
2018 if (GET_CODE (*iter) == VALUE && CSELIB_VAL_PTR (*iter)->uid > minuid)
2019 return true;
2020 return false;
2023 /* Convert the address X into something we can use. This is done by returning
2024 it unchanged unless it is a value; in the latter case we call cselib to get
2025 a more useful rtx. */
2028 get_addr (rtx x)
2030 cselib_val *v;
2031 struct elt_loc_list *l;
2033 if (GET_CODE (x) != VALUE)
2034 return x;
2035 v = CSELIB_VAL_PTR (x);
2036 if (v)
2038 bool have_equivs = cselib_have_permanent_equivalences ();
2039 if (have_equivs)
2040 v = canonical_cselib_val (v);
2041 for (l = v->locs; l; l = l->next)
2042 if (CONSTANT_P (l->loc))
2043 return l->loc;
2044 for (l = v->locs; l; l = l->next)
2045 if (!REG_P (l->loc) && !MEM_P (l->loc)
2046 /* Avoid infinite recursion when potentially dealing with
2047 var-tracking artificial equivalences, by skipping the
2048 equivalences themselves, and not choosing expressions
2049 that refer to newer VALUEs. */
2050 && (!have_equivs
2051 || (GET_CODE (l->loc) != VALUE
2052 && !refs_newer_value_p (l->loc, x))))
2053 return l->loc;
2054 if (have_equivs)
2056 for (l = v->locs; l; l = l->next)
2057 if (REG_P (l->loc)
2058 || (GET_CODE (l->loc) != VALUE
2059 && !refs_newer_value_p (l->loc, x)))
2060 return l->loc;
2061 /* Return the canonical value. */
2062 return v->val_rtx;
2064 if (v->locs)
2065 return v->locs->loc;
2067 return x;
2070 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
2071 where SIZE is the size in bytes of the memory reference. If ADDR
2072 is not modified by the memory reference then ADDR is returned. */
2074 static rtx
2075 addr_side_effect_eval (rtx addr, int size, int n_refs)
2077 int offset = 0;
2079 switch (GET_CODE (addr))
2081 case PRE_INC:
2082 offset = (n_refs + 1) * size;
2083 break;
2084 case PRE_DEC:
2085 offset = -(n_refs + 1) * size;
2086 break;
2087 case POST_INC:
2088 offset = n_refs * size;
2089 break;
2090 case POST_DEC:
2091 offset = -n_refs * size;
2092 break;
2094 default:
2095 return addr;
2098 if (offset)
2099 addr = gen_rtx_PLUS (GET_MODE (addr), XEXP (addr, 0),
2100 gen_int_mode (offset, GET_MODE (addr)));
2101 else
2102 addr = XEXP (addr, 0);
2103 addr = canon_rtx (addr);
2105 return addr;
2108 /* Return TRUE if an object X sized at XSIZE bytes and another object
2109 Y sized at YSIZE bytes, starting C bytes after X, may overlap. If
2110 any of the sizes is zero, assume an overlap, otherwise use the
2111 absolute value of the sizes as the actual sizes. */
2113 static inline bool
2114 offset_overlap_p (HOST_WIDE_INT c, int xsize, int ysize)
2116 return (xsize == 0 || ysize == 0
2117 || (c >= 0
2118 ? (abs (xsize) > c)
2119 : (abs (ysize) > -c)));
2122 /* Return one if X and Y (memory addresses) reference the
2123 same location in memory or if the references overlap.
2124 Return zero if they do not overlap, else return
2125 minus one in which case they still might reference the same location.
2127 C is an offset accumulator. When
2128 C is nonzero, we are testing aliases between X and Y + C.
2129 XSIZE is the size in bytes of the X reference,
2130 similarly YSIZE is the size in bytes for Y.
2131 Expect that canon_rtx has been already called for X and Y.
2133 If XSIZE or YSIZE is zero, we do not know the amount of memory being
2134 referenced (the reference was BLKmode), so make the most pessimistic
2135 assumptions.
2137 If XSIZE or YSIZE is negative, we may access memory outside the object
2138 being referenced as a side effect. This can happen when using AND to
2139 align memory references, as is done on the Alpha.
2141 Nice to notice that varying addresses cannot conflict with fp if no
2142 local variables had their addresses taken, but that's too hard now.
2144 ??? Contrary to the tree alias oracle this does not return
2145 one for X + non-constant and Y + non-constant when X and Y are equal.
2146 If that is fixed the TBAA hack for union type-punning can be removed. */
2148 static int
2149 memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c)
2151 if (GET_CODE (x) == VALUE)
2153 if (REG_P (y))
2155 struct elt_loc_list *l = NULL;
2156 if (CSELIB_VAL_PTR (x))
2157 for (l = canonical_cselib_val (CSELIB_VAL_PTR (x))->locs;
2158 l; l = l->next)
2159 if (REG_P (l->loc) && rtx_equal_for_memref_p (l->loc, y))
2160 break;
2161 if (l)
2162 x = y;
2163 else
2164 x = get_addr (x);
2166 /* Don't call get_addr if y is the same VALUE. */
2167 else if (x != y)
2168 x = get_addr (x);
2170 if (GET_CODE (y) == VALUE)
2172 if (REG_P (x))
2174 struct elt_loc_list *l = NULL;
2175 if (CSELIB_VAL_PTR (y))
2176 for (l = canonical_cselib_val (CSELIB_VAL_PTR (y))->locs;
2177 l; l = l->next)
2178 if (REG_P (l->loc) && rtx_equal_for_memref_p (l->loc, x))
2179 break;
2180 if (l)
2181 y = x;
2182 else
2183 y = get_addr (y);
2185 /* Don't call get_addr if x is the same VALUE. */
2186 else if (y != x)
2187 y = get_addr (y);
2189 if (GET_CODE (x) == HIGH)
2190 x = XEXP (x, 0);
2191 else if (GET_CODE (x) == LO_SUM)
2192 x = XEXP (x, 1);
2193 else
2194 x = addr_side_effect_eval (x, abs (xsize), 0);
2195 if (GET_CODE (y) == HIGH)
2196 y = XEXP (y, 0);
2197 else if (GET_CODE (y) == LO_SUM)
2198 y = XEXP (y, 1);
2199 else
2200 y = addr_side_effect_eval (y, abs (ysize), 0);
2202 if (rtx_equal_for_memref_p (x, y))
2204 return offset_overlap_p (c, xsize, ysize);
2207 /* This code used to check for conflicts involving stack references and
2208 globals but the base address alias code now handles these cases. */
2210 if (GET_CODE (x) == PLUS)
2212 /* The fact that X is canonicalized means that this
2213 PLUS rtx is canonicalized. */
2214 rtx x0 = XEXP (x, 0);
2215 rtx x1 = XEXP (x, 1);
2217 /* However, VALUEs might end up in different positions even in
2218 canonical PLUSes. Comparing their addresses is enough. */
2219 if (x0 == y)
2220 return memrefs_conflict_p (xsize, x1, ysize, const0_rtx, c);
2221 else if (x1 == y)
2222 return memrefs_conflict_p (xsize, x0, ysize, const0_rtx, c);
2224 if (GET_CODE (y) == PLUS)
2226 /* The fact that Y is canonicalized means that this
2227 PLUS rtx is canonicalized. */
2228 rtx y0 = XEXP (y, 0);
2229 rtx y1 = XEXP (y, 1);
2231 if (x0 == y1)
2232 return memrefs_conflict_p (xsize, x1, ysize, y0, c);
2233 if (x1 == y0)
2234 return memrefs_conflict_p (xsize, x0, ysize, y1, c);
2236 if (rtx_equal_for_memref_p (x1, y1))
2237 return memrefs_conflict_p (xsize, x0, ysize, y0, c);
2238 if (rtx_equal_for_memref_p (x0, y0))
2239 return memrefs_conflict_p (xsize, x1, ysize, y1, c);
2240 if (CONST_INT_P (x1))
2242 if (CONST_INT_P (y1))
2243 return memrefs_conflict_p (xsize, x0, ysize, y0,
2244 c - INTVAL (x1) + INTVAL (y1));
2245 else
2246 return memrefs_conflict_p (xsize, x0, ysize, y,
2247 c - INTVAL (x1));
2249 else if (CONST_INT_P (y1))
2250 return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
2252 return -1;
2254 else if (CONST_INT_P (x1))
2255 return memrefs_conflict_p (xsize, x0, ysize, y, c - INTVAL (x1));
2257 else if (GET_CODE (y) == PLUS)
2259 /* The fact that Y is canonicalized means that this
2260 PLUS rtx is canonicalized. */
2261 rtx y0 = XEXP (y, 0);
2262 rtx y1 = XEXP (y, 1);
2264 if (x == y0)
2265 return memrefs_conflict_p (xsize, const0_rtx, ysize, y1, c);
2266 if (x == y1)
2267 return memrefs_conflict_p (xsize, const0_rtx, ysize, y0, c);
2269 if (CONST_INT_P (y1))
2270 return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
2271 else
2272 return -1;
2275 if (GET_CODE (x) == GET_CODE (y))
2276 switch (GET_CODE (x))
2278 case MULT:
2280 /* Handle cases where we expect the second operands to be the
2281 same, and check only whether the first operand would conflict
2282 or not. */
2283 rtx x0, y0;
2284 rtx x1 = canon_rtx (XEXP (x, 1));
2285 rtx y1 = canon_rtx (XEXP (y, 1));
2286 if (! rtx_equal_for_memref_p (x1, y1))
2287 return -1;
2288 x0 = canon_rtx (XEXP (x, 0));
2289 y0 = canon_rtx (XEXP (y, 0));
2290 if (rtx_equal_for_memref_p (x0, y0))
2291 return offset_overlap_p (c, xsize, ysize);
2293 /* Can't properly adjust our sizes. */
2294 if (!CONST_INT_P (x1))
2295 return -1;
2296 xsize /= INTVAL (x1);
2297 ysize /= INTVAL (x1);
2298 c /= INTVAL (x1);
2299 return memrefs_conflict_p (xsize, x0, ysize, y0, c);
2302 default:
2303 break;
2306 /* Deal with alignment ANDs by adjusting offset and size so as to
2307 cover the maximum range, without taking any previously known
2308 alignment into account. Make a size negative after such an
2309 adjustments, so that, if we end up with e.g. two SYMBOL_REFs, we
2310 assume a potential overlap, because they may end up in contiguous
2311 memory locations and the stricter-alignment access may span over
2312 part of both. */
2313 if (GET_CODE (x) == AND && CONST_INT_P (XEXP (x, 1)))
2315 HOST_WIDE_INT sc = INTVAL (XEXP (x, 1));
2316 unsigned HOST_WIDE_INT uc = sc;
2317 if (sc < 0 && -uc == (uc & -uc))
2319 if (xsize > 0)
2320 xsize = -xsize;
2321 if (xsize)
2322 xsize += sc + 1;
2323 c -= sc + 1;
2324 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
2325 ysize, y, c);
2328 if (GET_CODE (y) == AND && CONST_INT_P (XEXP (y, 1)))
2330 HOST_WIDE_INT sc = INTVAL (XEXP (y, 1));
2331 unsigned HOST_WIDE_INT uc = sc;
2332 if (sc < 0 && -uc == (uc & -uc))
2334 if (ysize > 0)
2335 ysize = -ysize;
2336 if (ysize)
2337 ysize += sc + 1;
2338 c += sc + 1;
2339 return memrefs_conflict_p (xsize, x,
2340 ysize, canon_rtx (XEXP (y, 0)), c);
2344 if (CONSTANT_P (x))
2346 if (CONST_INT_P (x) && CONST_INT_P (y))
2348 c += (INTVAL (y) - INTVAL (x));
2349 return offset_overlap_p (c, xsize, ysize);
2352 if (GET_CODE (x) == CONST)
2354 if (GET_CODE (y) == CONST)
2355 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
2356 ysize, canon_rtx (XEXP (y, 0)), c);
2357 else
2358 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
2359 ysize, y, c);
2361 if (GET_CODE (y) == CONST)
2362 return memrefs_conflict_p (xsize, x, ysize,
2363 canon_rtx (XEXP (y, 0)), c);
2365 /* Assume a potential overlap for symbolic addresses that went
2366 through alignment adjustments (i.e., that have negative
2367 sizes), because we can't know how far they are from each
2368 other. */
2369 if (CONSTANT_P (y))
2370 return (xsize < 0 || ysize < 0 || offset_overlap_p (c, xsize, ysize));
2372 return -1;
2375 return -1;
2378 /* Functions to compute memory dependencies.
2380 Since we process the insns in execution order, we can build tables
2381 to keep track of what registers are fixed (and not aliased), what registers
2382 are varying in known ways, and what registers are varying in unknown
2383 ways.
2385 If both memory references are volatile, then there must always be a
2386 dependence between the two references, since their order can not be
2387 changed. A volatile and non-volatile reference can be interchanged
2388 though.
2390 We also must allow AND addresses, because they may generate accesses
2391 outside the object being referenced. This is used to generate aligned
2392 addresses from unaligned addresses, for instance, the alpha
2393 storeqi_unaligned pattern. */
2395 /* Read dependence: X is read after read in MEM takes place. There can
2396 only be a dependence here if both reads are volatile, or if either is
2397 an explicit barrier. */
2400 read_dependence (const_rtx mem, const_rtx x)
2402 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2403 return true;
2404 if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER
2405 || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER)
2406 return true;
2407 return false;
2410 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
2412 static tree
2413 decl_for_component_ref (tree x)
2417 x = TREE_OPERAND (x, 0);
2419 while (x && TREE_CODE (x) == COMPONENT_REF);
2421 return x && DECL_P (x) ? x : NULL_TREE;
2424 /* Walk up the COMPONENT_REF list in X and adjust *OFFSET to compensate
2425 for the offset of the field reference. *KNOWN_P says whether the
2426 offset is known. */
2428 static void
2429 adjust_offset_for_component_ref (tree x, bool *known_p,
2430 HOST_WIDE_INT *offset)
2432 if (!*known_p)
2433 return;
2436 tree xoffset = component_ref_field_offset (x);
2437 tree field = TREE_OPERAND (x, 1);
2438 if (TREE_CODE (xoffset) != INTEGER_CST)
2440 *known_p = false;
2441 return;
2444 offset_int woffset
2445 = (wi::to_offset (xoffset)
2446 + wi::lrshift (wi::to_offset (DECL_FIELD_BIT_OFFSET (field)),
2447 LOG2_BITS_PER_UNIT));
2448 if (!wi::fits_uhwi_p (woffset))
2450 *known_p = false;
2451 return;
2453 *offset += woffset.to_uhwi ();
2455 x = TREE_OPERAND (x, 0);
2457 while (x && TREE_CODE (x) == COMPONENT_REF);
2460 /* Return nonzero if we can determine the exprs corresponding to memrefs
2461 X and Y and they do not overlap.
2462 If LOOP_VARIANT is set, skip offset-based disambiguation */
2465 nonoverlapping_memrefs_p (const_rtx x, const_rtx y, bool loop_invariant)
2467 tree exprx = MEM_EXPR (x), expry = MEM_EXPR (y);
2468 rtx rtlx, rtly;
2469 rtx basex, basey;
2470 bool moffsetx_known_p, moffsety_known_p;
2471 HOST_WIDE_INT moffsetx = 0, moffsety = 0;
2472 HOST_WIDE_INT offsetx = 0, offsety = 0, sizex, sizey;
2474 /* Unless both have exprs, we can't tell anything. */
2475 if (exprx == 0 || expry == 0)
2476 return 0;
2478 /* For spill-slot accesses make sure we have valid offsets. */
2479 if ((exprx == get_spill_slot_decl (false)
2480 && ! MEM_OFFSET_KNOWN_P (x))
2481 || (expry == get_spill_slot_decl (false)
2482 && ! MEM_OFFSET_KNOWN_P (y)))
2483 return 0;
2485 /* If the field reference test failed, look at the DECLs involved. */
2486 moffsetx_known_p = MEM_OFFSET_KNOWN_P (x);
2487 if (moffsetx_known_p)
2488 moffsetx = MEM_OFFSET (x);
2489 if (TREE_CODE (exprx) == COMPONENT_REF)
2491 tree t = decl_for_component_ref (exprx);
2492 if (! t)
2493 return 0;
2494 adjust_offset_for_component_ref (exprx, &moffsetx_known_p, &moffsetx);
2495 exprx = t;
2498 moffsety_known_p = MEM_OFFSET_KNOWN_P (y);
2499 if (moffsety_known_p)
2500 moffsety = MEM_OFFSET (y);
2501 if (TREE_CODE (expry) == COMPONENT_REF)
2503 tree t = decl_for_component_ref (expry);
2504 if (! t)
2505 return 0;
2506 adjust_offset_for_component_ref (expry, &moffsety_known_p, &moffsety);
2507 expry = t;
2510 if (! DECL_P (exprx) || ! DECL_P (expry))
2511 return 0;
2513 /* If we refer to different gimple registers, or one gimple register
2514 and one non-gimple-register, we know they can't overlap. First,
2515 gimple registers don't have their addresses taken. Now, there
2516 could be more than one stack slot for (different versions of) the
2517 same gimple register, but we can presumably tell they don't
2518 overlap based on offsets from stack base addresses elsewhere.
2519 It's important that we don't proceed to DECL_RTL, because gimple
2520 registers may not pass DECL_RTL_SET_P, and make_decl_rtl won't be
2521 able to do anything about them since no SSA information will have
2522 remained to guide it. */
2523 if (is_gimple_reg (exprx) || is_gimple_reg (expry))
2524 return exprx != expry
2525 || (moffsetx_known_p && moffsety_known_p
2526 && MEM_SIZE_KNOWN_P (x) && MEM_SIZE_KNOWN_P (y)
2527 && !offset_overlap_p (moffsety - moffsetx,
2528 MEM_SIZE (x), MEM_SIZE (y)));
2530 /* With invalid code we can end up storing into the constant pool.
2531 Bail out to avoid ICEing when creating RTL for this.
2532 See gfortran.dg/lto/20091028-2_0.f90. */
2533 if (TREE_CODE (exprx) == CONST_DECL
2534 || TREE_CODE (expry) == CONST_DECL)
2535 return 1;
2537 rtlx = DECL_RTL (exprx);
2538 rtly = DECL_RTL (expry);
2540 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
2541 can't overlap unless they are the same because we never reuse that part
2542 of the stack frame used for locals for spilled pseudos. */
2543 if ((!MEM_P (rtlx) || !MEM_P (rtly))
2544 && ! rtx_equal_p (rtlx, rtly))
2545 return 1;
2547 /* If we have MEMs referring to different address spaces (which can
2548 potentially overlap), we cannot easily tell from the addresses
2549 whether the references overlap. */
2550 if (MEM_P (rtlx) && MEM_P (rtly)
2551 && MEM_ADDR_SPACE (rtlx) != MEM_ADDR_SPACE (rtly))
2552 return 0;
2554 /* Get the base and offsets of both decls. If either is a register, we
2555 know both are and are the same, so use that as the base. The only
2556 we can avoid overlap is if we can deduce that they are nonoverlapping
2557 pieces of that decl, which is very rare. */
2558 basex = MEM_P (rtlx) ? XEXP (rtlx, 0) : rtlx;
2559 if (GET_CODE (basex) == PLUS && CONST_INT_P (XEXP (basex, 1)))
2560 offsetx = INTVAL (XEXP (basex, 1)), basex = XEXP (basex, 0);
2562 basey = MEM_P (rtly) ? XEXP (rtly, 0) : rtly;
2563 if (GET_CODE (basey) == PLUS && CONST_INT_P (XEXP (basey, 1)))
2564 offsety = INTVAL (XEXP (basey, 1)), basey = XEXP (basey, 0);
2566 /* If the bases are different, we know they do not overlap if both
2567 are constants or if one is a constant and the other a pointer into the
2568 stack frame. Otherwise a different base means we can't tell if they
2569 overlap or not. */
2570 if (! rtx_equal_p (basex, basey))
2571 return ((CONSTANT_P (basex) && CONSTANT_P (basey))
2572 || (CONSTANT_P (basex) && REG_P (basey)
2573 && REGNO_PTR_FRAME_P (REGNO (basey)))
2574 || (CONSTANT_P (basey) && REG_P (basex)
2575 && REGNO_PTR_FRAME_P (REGNO (basex))));
2577 /* Offset based disambiguation not appropriate for loop invariant */
2578 if (loop_invariant)
2579 return 0;
2581 sizex = (!MEM_P (rtlx) ? (int) GET_MODE_SIZE (GET_MODE (rtlx))
2582 : MEM_SIZE_KNOWN_P (rtlx) ? MEM_SIZE (rtlx)
2583 : -1);
2584 sizey = (!MEM_P (rtly) ? (int) GET_MODE_SIZE (GET_MODE (rtly))
2585 : MEM_SIZE_KNOWN_P (rtly) ? MEM_SIZE (rtly)
2586 : -1);
2588 /* If we have an offset for either memref, it can update the values computed
2589 above. */
2590 if (moffsetx_known_p)
2591 offsetx += moffsetx, sizex -= moffsetx;
2592 if (moffsety_known_p)
2593 offsety += moffsety, sizey -= moffsety;
2595 /* If a memref has both a size and an offset, we can use the smaller size.
2596 We can't do this if the offset isn't known because we must view this
2597 memref as being anywhere inside the DECL's MEM. */
2598 if (MEM_SIZE_KNOWN_P (x) && moffsetx_known_p)
2599 sizex = MEM_SIZE (x);
2600 if (MEM_SIZE_KNOWN_P (y) && moffsety_known_p)
2601 sizey = MEM_SIZE (y);
2603 /* Put the values of the memref with the lower offset in X's values. */
2604 if (offsetx > offsety)
2606 std::swap (offsetx, offsety);
2607 std::swap (sizex, sizey);
2610 /* If we don't know the size of the lower-offset value, we can't tell
2611 if they conflict. Otherwise, we do the test. */
2612 return sizex >= 0 && offsety >= offsetx + sizex;
2615 /* Helper for true_dependence and canon_true_dependence.
2616 Checks for true dependence: X is read after store in MEM takes place.
2618 If MEM_CANONICALIZED is FALSE, then X_ADDR and MEM_ADDR should be
2619 NULL_RTX, and the canonical addresses of MEM and X are both computed
2620 here. If MEM_CANONICALIZED, then MEM must be already canonicalized.
2622 If X_ADDR is non-NULL, it is used in preference of XEXP (x, 0).
2624 Returns 1 if there is a true dependence, 0 otherwise. */
2626 static int
2627 true_dependence_1 (const_rtx mem, machine_mode mem_mode, rtx mem_addr,
2628 const_rtx x, rtx x_addr, bool mem_canonicalized)
2630 rtx true_mem_addr;
2631 rtx base;
2632 int ret;
2634 gcc_checking_assert (mem_canonicalized ? (mem_addr != NULL_RTX)
2635 : (mem_addr == NULL_RTX && x_addr == NULL_RTX));
2637 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2638 return 1;
2640 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2641 This is used in epilogue deallocation functions, and in cselib. */
2642 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
2643 return 1;
2644 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
2645 return 1;
2646 if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER
2647 || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER)
2648 return 1;
2650 if (! x_addr)
2651 x_addr = XEXP (x, 0);
2652 x_addr = get_addr (x_addr);
2654 if (! mem_addr)
2656 mem_addr = XEXP (mem, 0);
2657 if (mem_mode == VOIDmode)
2658 mem_mode = GET_MODE (mem);
2660 true_mem_addr = get_addr (mem_addr);
2662 /* Read-only memory is by definition never modified, and therefore can't
2663 conflict with anything. However, don't assume anything when AND
2664 addresses are involved and leave to the code below to determine
2665 dependence. We don't expect to find read-only set on MEM, but
2666 stupid user tricks can produce them, so don't die. */
2667 if (MEM_READONLY_P (x)
2668 && GET_CODE (x_addr) != AND
2669 && GET_CODE (true_mem_addr) != AND)
2670 return 0;
2672 /* If we have MEMs referring to different address spaces (which can
2673 potentially overlap), we cannot easily tell from the addresses
2674 whether the references overlap. */
2675 if (MEM_ADDR_SPACE (mem) != MEM_ADDR_SPACE (x))
2676 return 1;
2678 base = find_base_term (x_addr);
2679 if (base && (GET_CODE (base) == LABEL_REF
2680 || (GET_CODE (base) == SYMBOL_REF
2681 && CONSTANT_POOL_ADDRESS_P (base))))
2682 return 0;
2684 rtx mem_base = find_base_term (true_mem_addr);
2685 if (! base_alias_check (x_addr, base, true_mem_addr, mem_base,
2686 GET_MODE (x), mem_mode))
2687 return 0;
2689 x_addr = canon_rtx (x_addr);
2690 if (!mem_canonicalized)
2691 mem_addr = canon_rtx (true_mem_addr);
2693 if ((ret = memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
2694 SIZE_FOR_MODE (x), x_addr, 0)) != -1)
2695 return ret;
2697 if (mems_in_disjoint_alias_sets_p (x, mem))
2698 return 0;
2700 if (nonoverlapping_memrefs_p (mem, x, false))
2701 return 0;
2703 return rtx_refs_may_alias_p (x, mem, true);
2706 /* True dependence: X is read after store in MEM takes place. */
2709 true_dependence (const_rtx mem, machine_mode mem_mode, const_rtx x)
2711 return true_dependence_1 (mem, mem_mode, NULL_RTX,
2712 x, NULL_RTX, /*mem_canonicalized=*/false);
2715 /* Canonical true dependence: X is read after store in MEM takes place.
2716 Variant of true_dependence which assumes MEM has already been
2717 canonicalized (hence we no longer do that here).
2718 The mem_addr argument has been added, since true_dependence_1 computed
2719 this value prior to canonicalizing. */
2722 canon_true_dependence (const_rtx mem, machine_mode mem_mode, rtx mem_addr,
2723 const_rtx x, rtx x_addr)
2725 return true_dependence_1 (mem, mem_mode, mem_addr,
2726 x, x_addr, /*mem_canonicalized=*/true);
2729 /* Returns nonzero if a write to X might alias a previous read from
2730 (or, if WRITEP is true, a write to) MEM.
2731 If X_CANONCALIZED is true, then X_ADDR is the canonicalized address of X,
2732 and X_MODE the mode for that access.
2733 If MEM_CANONICALIZED is true, MEM is canonicalized. */
2735 static int
2736 write_dependence_p (const_rtx mem,
2737 const_rtx x, machine_mode x_mode, rtx x_addr,
2738 bool mem_canonicalized, bool x_canonicalized, bool writep)
2740 rtx mem_addr;
2741 rtx true_mem_addr, true_x_addr;
2742 rtx base;
2743 int ret;
2745 gcc_checking_assert (x_canonicalized
2746 ? (x_addr != NULL_RTX && x_mode != VOIDmode)
2747 : (x_addr == NULL_RTX && x_mode == VOIDmode));
2749 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2750 return 1;
2752 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2753 This is used in epilogue deallocation functions. */
2754 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
2755 return 1;
2756 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
2757 return 1;
2758 if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER
2759 || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER)
2760 return 1;
2762 if (!x_addr)
2763 x_addr = XEXP (x, 0);
2764 true_x_addr = get_addr (x_addr);
2766 mem_addr = XEXP (mem, 0);
2767 true_mem_addr = get_addr (mem_addr);
2769 /* A read from read-only memory can't conflict with read-write memory.
2770 Don't assume anything when AND addresses are involved and leave to
2771 the code below to determine dependence. */
2772 if (!writep
2773 && MEM_READONLY_P (mem)
2774 && GET_CODE (true_x_addr) != AND
2775 && GET_CODE (true_mem_addr) != AND)
2776 return 0;
2778 /* If we have MEMs referring to different address spaces (which can
2779 potentially overlap), we cannot easily tell from the addresses
2780 whether the references overlap. */
2781 if (MEM_ADDR_SPACE (mem) != MEM_ADDR_SPACE (x))
2782 return 1;
2784 base = find_base_term (true_mem_addr);
2785 if (! writep
2786 && base
2787 && (GET_CODE (base) == LABEL_REF
2788 || (GET_CODE (base) == SYMBOL_REF
2789 && CONSTANT_POOL_ADDRESS_P (base))))
2790 return 0;
2792 rtx x_base = find_base_term (true_x_addr);
2793 if (! base_alias_check (true_x_addr, x_base, true_mem_addr, base,
2794 GET_MODE (x), GET_MODE (mem)))
2795 return 0;
2797 if (!x_canonicalized)
2799 x_addr = canon_rtx (true_x_addr);
2800 x_mode = GET_MODE (x);
2802 if (!mem_canonicalized)
2803 mem_addr = canon_rtx (true_mem_addr);
2805 if ((ret = memrefs_conflict_p (SIZE_FOR_MODE (mem), mem_addr,
2806 GET_MODE_SIZE (x_mode), x_addr, 0)) != -1)
2807 return ret;
2809 if (nonoverlapping_memrefs_p (x, mem, false))
2810 return 0;
2812 return rtx_refs_may_alias_p (x, mem, false);
2815 /* Anti dependence: X is written after read in MEM takes place. */
2818 anti_dependence (const_rtx mem, const_rtx x)
2820 return write_dependence_p (mem, x, VOIDmode, NULL_RTX,
2821 /*mem_canonicalized=*/false,
2822 /*x_canonicalized*/false, /*writep=*/false);
2825 /* Likewise, but we already have a canonicalized MEM, and X_ADDR for X.
2826 Also, consider X in X_MODE (which might be from an enclosing
2827 STRICT_LOW_PART / ZERO_EXTRACT).
2828 If MEM_CANONICALIZED is true, MEM is canonicalized. */
2831 canon_anti_dependence (const_rtx mem, bool mem_canonicalized,
2832 const_rtx x, machine_mode x_mode, rtx x_addr)
2834 return write_dependence_p (mem, x, x_mode, x_addr,
2835 mem_canonicalized, /*x_canonicalized=*/true,
2836 /*writep=*/false);
2839 /* Output dependence: X is written after store in MEM takes place. */
2842 output_dependence (const_rtx mem, const_rtx x)
2844 return write_dependence_p (mem, x, VOIDmode, NULL_RTX,
2845 /*mem_canonicalized=*/false,
2846 /*x_canonicalized*/false, /*writep=*/true);
2851 /* Check whether X may be aliased with MEM. Don't do offset-based
2852 memory disambiguation & TBAA. */
2854 may_alias_p (const_rtx mem, const_rtx x)
2856 rtx x_addr, mem_addr;
2858 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2859 return 1;
2861 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2862 This is used in epilogue deallocation functions. */
2863 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
2864 return 1;
2865 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
2866 return 1;
2867 if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER
2868 || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER)
2869 return 1;
2871 x_addr = XEXP (x, 0);
2872 x_addr = get_addr (x_addr);
2874 mem_addr = XEXP (mem, 0);
2875 mem_addr = get_addr (mem_addr);
2877 /* Read-only memory is by definition never modified, and therefore can't
2878 conflict with anything. However, don't assume anything when AND
2879 addresses are involved and leave to the code below to determine
2880 dependence. We don't expect to find read-only set on MEM, but
2881 stupid user tricks can produce them, so don't die. */
2882 if (MEM_READONLY_P (x)
2883 && GET_CODE (x_addr) != AND
2884 && GET_CODE (mem_addr) != AND)
2885 return 0;
2887 /* If we have MEMs referring to different address spaces (which can
2888 potentially overlap), we cannot easily tell from the addresses
2889 whether the references overlap. */
2890 if (MEM_ADDR_SPACE (mem) != MEM_ADDR_SPACE (x))
2891 return 1;
2893 rtx x_base = find_base_term (x_addr);
2894 rtx mem_base = find_base_term (mem_addr);
2895 if (! base_alias_check (x_addr, x_base, mem_addr, mem_base,
2896 GET_MODE (x), GET_MODE (mem_addr)))
2897 return 0;
2899 if (nonoverlapping_memrefs_p (mem, x, true))
2900 return 0;
2902 /* TBAA not valid for loop_invarint */
2903 return rtx_refs_may_alias_p (x, mem, false);
2906 void
2907 init_alias_target (void)
2909 int i;
2911 if (!arg_base_value)
2912 arg_base_value = gen_rtx_ADDRESS (VOIDmode, 0);
2914 memset (static_reg_base_value, 0, sizeof static_reg_base_value);
2916 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2917 /* Check whether this register can hold an incoming pointer
2918 argument. FUNCTION_ARG_REGNO_P tests outgoing register
2919 numbers, so translate if necessary due to register windows. */
2920 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i))
2921 && HARD_REGNO_MODE_OK (i, Pmode))
2922 static_reg_base_value[i] = arg_base_value;
2924 static_reg_base_value[STACK_POINTER_REGNUM]
2925 = unique_base_value (UNIQUE_BASE_VALUE_SP);
2926 static_reg_base_value[ARG_POINTER_REGNUM]
2927 = unique_base_value (UNIQUE_BASE_VALUE_ARGP);
2928 static_reg_base_value[FRAME_POINTER_REGNUM]
2929 = unique_base_value (UNIQUE_BASE_VALUE_FP);
2930 if (!HARD_FRAME_POINTER_IS_FRAME_POINTER)
2931 static_reg_base_value[HARD_FRAME_POINTER_REGNUM]
2932 = unique_base_value (UNIQUE_BASE_VALUE_HFP);
2935 /* Set MEMORY_MODIFIED when X modifies DATA (that is assumed
2936 to be memory reference. */
2937 static bool memory_modified;
2938 static void
2939 memory_modified_1 (rtx x, const_rtx pat ATTRIBUTE_UNUSED, void *data)
2941 if (MEM_P (x))
2943 if (anti_dependence (x, (const_rtx)data) || output_dependence (x, (const_rtx)data))
2944 memory_modified = true;
2949 /* Return true when INSN possibly modify memory contents of MEM
2950 (i.e. address can be modified). */
2951 bool
2952 memory_modified_in_insn_p (const_rtx mem, const_rtx insn)
2954 if (!INSN_P (insn))
2955 return false;
2956 memory_modified = false;
2957 note_stores (PATTERN (insn), memory_modified_1, CONST_CAST_RTX(mem));
2958 return memory_modified;
2961 /* Return TRUE if the destination of a set is rtx identical to
2962 ITEM. */
2963 static inline bool
2964 set_dest_equal_p (const_rtx set, const_rtx item)
2966 rtx dest = SET_DEST (set);
2967 return rtx_equal_p (dest, item);
2970 /* Like memory_modified_in_insn_p, but return TRUE if INSN will
2971 *DEFINITELY* modify the memory contents of MEM. */
2972 bool
2973 memory_must_be_modified_in_insn_p (const_rtx mem, const_rtx insn)
2975 if (!INSN_P (insn))
2976 return false;
2977 insn = PATTERN (insn);
2978 if (GET_CODE (insn) == SET)
2979 return set_dest_equal_p (insn, mem);
2980 else if (GET_CODE (insn) == PARALLEL)
2982 int i;
2983 for (i = 0; i < XVECLEN (insn, 0); i++)
2985 rtx sub = XVECEXP (insn, 0, i);
2986 if (GET_CODE (sub) == SET
2987 && set_dest_equal_p (sub, mem))
2988 return true;
2991 return false;
2994 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
2995 array. */
2997 void
2998 init_alias_analysis (void)
3000 unsigned int maxreg = max_reg_num ();
3001 int changed, pass;
3002 int i;
3003 unsigned int ui;
3004 rtx_insn *insn;
3005 rtx val;
3006 int rpo_cnt;
3007 int *rpo;
3009 timevar_push (TV_ALIAS_ANALYSIS);
3011 vec_safe_grow_cleared (reg_known_value, maxreg - FIRST_PSEUDO_REGISTER);
3012 reg_known_equiv_p = sbitmap_alloc (maxreg - FIRST_PSEUDO_REGISTER);
3013 bitmap_clear (reg_known_equiv_p);
3015 /* If we have memory allocated from the previous run, use it. */
3016 if (old_reg_base_value)
3017 reg_base_value = old_reg_base_value;
3019 if (reg_base_value)
3020 reg_base_value->truncate (0);
3022 vec_safe_grow_cleared (reg_base_value, maxreg);
3024 new_reg_base_value = XNEWVEC (rtx, maxreg);
3025 reg_seen = sbitmap_alloc (maxreg);
3027 /* The basic idea is that each pass through this loop will use the
3028 "constant" information from the previous pass to propagate alias
3029 information through another level of assignments.
3031 The propagation is done on the CFG in reverse post-order, to propagate
3032 things forward as far as possible in each iteration.
3034 This could get expensive if the assignment chains are long. Maybe
3035 we should throttle the number of iterations, possibly based on
3036 the optimization level or flag_expensive_optimizations.
3038 We could propagate more information in the first pass by making use
3039 of DF_REG_DEF_COUNT to determine immediately that the alias information
3040 for a pseudo is "constant".
3042 A program with an uninitialized variable can cause an infinite loop
3043 here. Instead of doing a full dataflow analysis to detect such problems
3044 we just cap the number of iterations for the loop.
3046 The state of the arrays for the set chain in question does not matter
3047 since the program has undefined behavior. */
3049 rpo = XNEWVEC (int, n_basic_blocks_for_fn (cfun));
3050 rpo_cnt = pre_and_rev_post_order_compute (NULL, rpo, false);
3052 /* The prologue/epilogue insns are not threaded onto the
3053 insn chain until after reload has completed. Thus,
3054 there is no sense wasting time checking if INSN is in
3055 the prologue/epilogue until after reload has completed. */
3056 bool could_be_prologue_epilogue = ((targetm.have_prologue ()
3057 || targetm.have_epilogue ())
3058 && reload_completed);
3060 pass = 0;
3063 /* Assume nothing will change this iteration of the loop. */
3064 changed = 0;
3066 /* We want to assign the same IDs each iteration of this loop, so
3067 start counting from one each iteration of the loop. */
3068 unique_id = 1;
3070 /* We're at the start of the function each iteration through the
3071 loop, so we're copying arguments. */
3072 copying_arguments = true;
3074 /* Wipe the potential alias information clean for this pass. */
3075 memset (new_reg_base_value, 0, maxreg * sizeof (rtx));
3077 /* Wipe the reg_seen array clean. */
3078 bitmap_clear (reg_seen);
3080 /* Initialize the alias information for this pass. */
3081 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3082 if (static_reg_base_value[i])
3084 new_reg_base_value[i] = static_reg_base_value[i];
3085 bitmap_set_bit (reg_seen, i);
3088 /* Walk the insns adding values to the new_reg_base_value array. */
3089 for (i = 0; i < rpo_cnt; i++)
3091 basic_block bb = BASIC_BLOCK_FOR_FN (cfun, rpo[i]);
3092 FOR_BB_INSNS (bb, insn)
3094 if (NONDEBUG_INSN_P (insn))
3096 rtx note, set;
3098 if (could_be_prologue_epilogue
3099 && prologue_epilogue_contains (insn))
3100 continue;
3102 /* If this insn has a noalias note, process it, Otherwise,
3103 scan for sets. A simple set will have no side effects
3104 which could change the base value of any other register. */
3106 if (GET_CODE (PATTERN (insn)) == SET
3107 && REG_NOTES (insn) != 0
3108 && find_reg_note (insn, REG_NOALIAS, NULL_RTX))
3109 record_set (SET_DEST (PATTERN (insn)), NULL_RTX, NULL);
3110 else
3111 note_stores (PATTERN (insn), record_set, NULL);
3113 set = single_set (insn);
3115 if (set != 0
3116 && REG_P (SET_DEST (set))
3117 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER)
3119 unsigned int regno = REGNO (SET_DEST (set));
3120 rtx src = SET_SRC (set);
3121 rtx t;
3123 note = find_reg_equal_equiv_note (insn);
3124 if (note && REG_NOTE_KIND (note) == REG_EQUAL
3125 && DF_REG_DEF_COUNT (regno) != 1)
3126 note = NULL_RTX;
3128 if (note != NULL_RTX
3129 && GET_CODE (XEXP (note, 0)) != EXPR_LIST
3130 && ! rtx_varies_p (XEXP (note, 0), 1)
3131 && ! reg_overlap_mentioned_p (SET_DEST (set),
3132 XEXP (note, 0)))
3134 set_reg_known_value (regno, XEXP (note, 0));
3135 set_reg_known_equiv_p (regno,
3136 REG_NOTE_KIND (note) == REG_EQUIV);
3138 else if (DF_REG_DEF_COUNT (regno) == 1
3139 && GET_CODE (src) == PLUS
3140 && REG_P (XEXP (src, 0))
3141 && (t = get_reg_known_value (REGNO (XEXP (src, 0))))
3142 && CONST_INT_P (XEXP (src, 1)))
3144 t = plus_constant (GET_MODE (src), t,
3145 INTVAL (XEXP (src, 1)));
3146 set_reg_known_value (regno, t);
3147 set_reg_known_equiv_p (regno, false);
3149 else if (DF_REG_DEF_COUNT (regno) == 1
3150 && ! rtx_varies_p (src, 1))
3152 set_reg_known_value (regno, src);
3153 set_reg_known_equiv_p (regno, false);
3157 else if (NOTE_P (insn)
3158 && NOTE_KIND (insn) == NOTE_INSN_FUNCTION_BEG)
3159 copying_arguments = false;
3163 /* Now propagate values from new_reg_base_value to reg_base_value. */
3164 gcc_assert (maxreg == (unsigned int) max_reg_num ());
3166 for (ui = 0; ui < maxreg; ui++)
3168 if (new_reg_base_value[ui]
3169 && new_reg_base_value[ui] != (*reg_base_value)[ui]
3170 && ! rtx_equal_p (new_reg_base_value[ui], (*reg_base_value)[ui]))
3172 (*reg_base_value)[ui] = new_reg_base_value[ui];
3173 changed = 1;
3177 while (changed && ++pass < MAX_ALIAS_LOOP_PASSES);
3178 XDELETEVEC (rpo);
3180 /* Fill in the remaining entries. */
3181 FOR_EACH_VEC_ELT (*reg_known_value, i, val)
3183 int regno = i + FIRST_PSEUDO_REGISTER;
3184 if (! val)
3185 set_reg_known_value (regno, regno_reg_rtx[regno]);
3188 /* Clean up. */
3189 free (new_reg_base_value);
3190 new_reg_base_value = 0;
3191 sbitmap_free (reg_seen);
3192 reg_seen = 0;
3193 timevar_pop (TV_ALIAS_ANALYSIS);
3196 /* Equate REG_BASE_VALUE (reg1) to REG_BASE_VALUE (reg2).
3197 Special API for var-tracking pass purposes. */
3199 void
3200 vt_equate_reg_base_value (const_rtx reg1, const_rtx reg2)
3202 (*reg_base_value)[REGNO (reg1)] = REG_BASE_VALUE (reg2);
3205 void
3206 end_alias_analysis (void)
3208 old_reg_base_value = reg_base_value;
3209 vec_free (reg_known_value);
3210 sbitmap_free (reg_known_equiv_p);
3213 void
3214 dump_alias_stats_in_alias_c (FILE *s)
3216 fprintf (s, " TBAA oracle: %llu disambiguations %llu queries\n"
3217 " %llu are in alias set 0\n"
3218 " %llu queries asked about the same object\n"
3219 " %llu queries asked about the same alias set\n"
3220 " %llu access volatile\n"
3221 " %llu are dependent in the DAG\n"
3222 " %llu are aritificially in conflict with void *\n",
3223 alias_stats.num_disambiguated,
3224 alias_stats.num_alias_zero + alias_stats.num_same_alias_set
3225 + alias_stats.num_same_objects + alias_stats.num_volatile
3226 + alias_stats.num_dag + alias_stats.num_disambiguated
3227 + alias_stats.num_universal,
3228 alias_stats.num_alias_zero, alias_stats.num_same_alias_set,
3229 alias_stats.num_same_objects, alias_stats.num_volatile,
3230 alias_stats.num_dag, alias_stats.num_universal);
3232 #include "gt-alias.h"