1 /* Alias analysis for GNU C
2 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
3 2007, 2008, 2009, 2010, 2011, 2012 Free Software Foundation, Inc.
4 Contributed by John Carr (jfc@mit.edu).
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
24 #include "coretypes.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
36 #include "diagnostic-core.h"
38 #include "splay-tree.h"
40 #include "langhooks.h"
44 #include "tree-pass.h"
46 #include "tree-ssa-alias.h"
47 #include "pointer-set.h"
48 #include "tree-flow.h"
50 /* The aliasing API provided here solves related but different problems:
52 Say there exists (in c)
66 Consider the four questions:
68 Can a store to x1 interfere with px2->y1?
69 Can a store to x1 interfere with px2->z2?
71 Can a store to x1 change the value pointed to by with py?
72 Can a store to x1 change the value pointed to by with pz?
74 The answer to these questions can be yes, yes, yes, and maybe.
76 The first two questions can be answered with a simple examination
77 of the type system. If structure X contains a field of type Y then
78 a store through a pointer to an X can overwrite any field that is
79 contained (recursively) in an X (unless we know that px1 != px2).
81 The last two of the questions can be solved in the same way as the
82 first two questions but this is too conservative. The observation
83 is that in some cases analysis we can know if which (if any) fields
84 are addressed and if those addresses are used in bad ways. This
85 analysis may be language specific. In C, arbitrary operations may
86 be applied to pointers. However, there is some indication that
87 this may be too conservative for some C++ types.
89 The pass ipa-type-escape does this analysis for the types whose
90 instances do not escape across the compilation boundary.
92 Historically in GCC, these two problems were combined and a single
93 data structure was used to represent the solution to these
94 problems. We now have two similar but different data structures,
95 The data structure to solve the last two question is similar to the
96 first, but does not contain have the fields in it whose address are
97 never taken. For types that do escape the compilation unit, the
98 data structures will have identical information.
101 /* The alias sets assigned to MEMs assist the back-end in determining
102 which MEMs can alias which other MEMs. In general, two MEMs in
103 different alias sets cannot alias each other, with one important
104 exception. Consider something like:
106 struct S { int i; double d; };
108 a store to an `S' can alias something of either type `int' or type
109 `double'. (However, a store to an `int' cannot alias a `double'
110 and vice versa.) We indicate this via a tree structure that looks
118 (The arrows are directed and point downwards.)
119 In this situation we say the alias set for `struct S' is the
120 `superset' and that those for `int' and `double' are `subsets'.
122 To see whether two alias sets can point to the same memory, we must
123 see if either alias set is a subset of the other. We need not trace
124 past immediate descendants, however, since we propagate all
125 grandchildren up one level.
127 Alias set zero is implicitly a superset of all other alias sets.
128 However, this is no actual entry for alias set zero. It is an
129 error to attempt to explicitly construct a subset of zero. */
131 struct GTY(()) alias_set_entry_d
{
132 /* The alias set number, as stored in MEM_ALIAS_SET. */
133 alias_set_type alias_set
;
135 /* Nonzero if would have a child of zero: this effectively makes this
136 alias set the same as alias set zero. */
139 /* The children of the alias set. These are not just the immediate
140 children, but, in fact, all descendants. So, if we have:
142 struct T { struct S s; float f; }
144 continuing our example above, the children here will be all of
145 `int', `double', `float', and `struct S'. */
146 splay_tree
GTY((param1_is (int), param2_is (int))) children
;
148 typedef struct alias_set_entry_d
*alias_set_entry
;
150 static int rtx_equal_for_memref_p (const_rtx
, const_rtx
);
151 static int memrefs_conflict_p (int, rtx
, int, rtx
, HOST_WIDE_INT
);
152 static void record_set (rtx
, const_rtx
, void *);
153 static int base_alias_check (rtx
, rtx
, enum machine_mode
,
155 static rtx
find_base_value (rtx
);
156 static int mems_in_disjoint_alias_sets_p (const_rtx
, const_rtx
);
157 static int insert_subset_children (splay_tree_node
, void*);
158 static alias_set_entry
get_alias_set_entry (alias_set_type
);
159 static int aliases_everything_p (const_rtx
);
160 static bool nonoverlapping_component_refs_p (const_tree
, const_tree
);
161 static tree
decl_for_component_ref (tree
);
162 static int write_dependence_p (const_rtx
, const_rtx
, int);
164 static void memory_modified_1 (rtx
, const_rtx
, void *);
166 /* Set up all info needed to perform alias analysis on memory references. */
168 /* Returns the size in bytes of the mode of X. */
169 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
171 /* Returns nonzero if MEM1 and MEM2 do not alias because they are in
172 different alias sets. We ignore alias sets in functions making use
173 of variable arguments because the va_arg macros on some systems are
175 #define DIFFERENT_ALIAS_SETS_P(MEM1, MEM2) \
176 mems_in_disjoint_alias_sets_p (MEM1, MEM2)
178 /* Cap the number of passes we make over the insns propagating alias
179 information through set chains. 10 is a completely arbitrary choice. */
180 #define MAX_ALIAS_LOOP_PASSES 10
182 /* reg_base_value[N] gives an address to which register N is related.
183 If all sets after the first add or subtract to the current value
184 or otherwise modify it so it does not point to a different top level
185 object, reg_base_value[N] is equal to the address part of the source
188 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
189 expressions represent three types of base:
191 1. incoming arguments. There is just one ADDRESS to represent all
192 arguments, since we do not know at this level whether accesses
193 based on different arguments can alias. The ADDRESS has id 0.
195 2. stack_pointer_rtx, frame_pointer_rtx, hard_frame_pointer_rtx
196 (if distinct from frame_pointer_rtx) and arg_pointer_rtx.
197 Each of these rtxes has a separate ADDRESS associated with it,
198 each with a negative id.
200 GCC is (and is required to be) precise in which register it
201 chooses to access a particular region of stack. We can therefore
202 assume that accesses based on one of these rtxes do not alias
203 accesses based on another of these rtxes.
205 3. bases that are derived from malloc()ed memory (REG_NOALIAS).
206 Each such piece of memory has a separate ADDRESS associated
207 with it, each with an id greater than 0.
209 Accesses based on one ADDRESS do not alias accesses based on other
210 ADDRESSes. Accesses based on ADDRESSes in groups (2) and (3) do not
211 alias globals either; the ADDRESSes have Pmode to indicate this.
212 The ADDRESS in group (1) _may_ alias globals; it has VOIDmode to
215 static GTY(()) VEC(rtx
,gc
) *reg_base_value
;
216 static rtx
*new_reg_base_value
;
218 /* The single VOIDmode ADDRESS that represents all argument bases.
220 static GTY(()) rtx arg_base_value
;
222 /* Used to allocate unique ids to each REG_NOALIAS ADDRESS. */
223 static int unique_id
;
225 /* We preserve the copy of old array around to avoid amount of garbage
226 produced. About 8% of garbage produced were attributed to this
228 static GTY((deletable
)) VEC(rtx
,gc
) *old_reg_base_value
;
230 /* Values of XINT (address, 0) of Pmode ADDRESS rtxes for special
232 #define UNIQUE_BASE_VALUE_SP -1
233 #define UNIQUE_BASE_VALUE_ARGP -2
234 #define UNIQUE_BASE_VALUE_FP -3
235 #define UNIQUE_BASE_VALUE_HFP -4
237 #define static_reg_base_value \
238 (this_target_rtl->x_static_reg_base_value)
240 #define REG_BASE_VALUE(X) \
241 (REGNO (X) < VEC_length (rtx, reg_base_value) \
242 ? VEC_index (rtx, reg_base_value, REGNO (X)) : 0)
244 /* Vector indexed by N giving the initial (unchanging) value known for
245 pseudo-register N. This vector is initialized in init_alias_analysis,
246 and does not change until end_alias_analysis is called. */
247 static GTY(()) VEC(rtx
,gc
) *reg_known_value
;
249 /* Vector recording for each reg_known_value whether it is due to a
250 REG_EQUIV note. Future passes (viz., reload) may replace the
251 pseudo with the equivalent expression and so we account for the
252 dependences that would be introduced if that happens.
254 The REG_EQUIV notes created in assign_parms may mention the arg
255 pointer, and there are explicit insns in the RTL that modify the
256 arg pointer. Thus we must ensure that such insns don't get
257 scheduled across each other because that would invalidate the
258 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
259 wrong, but solving the problem in the scheduler will likely give
260 better code, so we do it here. */
261 static sbitmap reg_known_equiv_p
;
263 /* True when scanning insns from the start of the rtl to the
264 NOTE_INSN_FUNCTION_BEG note. */
265 static bool copying_arguments
;
267 DEF_VEC_P(alias_set_entry
);
268 DEF_VEC_ALLOC_P(alias_set_entry
,gc
);
270 /* The splay-tree used to store the various alias set entries. */
271 static GTY (()) VEC(alias_set_entry
,gc
) *alias_sets
;
273 /* Build a decomposed reference object for querying the alias-oracle
274 from the MEM rtx and store it in *REF.
275 Returns false if MEM is not suitable for the alias-oracle. */
278 ao_ref_from_mem (ao_ref
*ref
, const_rtx mem
)
280 tree expr
= MEM_EXPR (mem
);
286 ao_ref_init (ref
, expr
);
288 /* Get the base of the reference and see if we have to reject or
290 base
= ao_ref_base (ref
);
291 if (base
== NULL_TREE
)
294 /* The tree oracle doesn't like to have these. */
295 if (TREE_CODE (base
) == FUNCTION_DECL
296 || TREE_CODE (base
) == LABEL_DECL
)
299 /* If this is a pointer dereference of a non-SSA_NAME punt.
300 ??? We could replace it with a pointer to anything. */
301 if ((INDIRECT_REF_P (base
)
302 || TREE_CODE (base
) == MEM_REF
)
303 && TREE_CODE (TREE_OPERAND (base
, 0)) != SSA_NAME
)
305 if (TREE_CODE (base
) == TARGET_MEM_REF
307 && TREE_CODE (TMR_BASE (base
)) != SSA_NAME
)
310 /* If this is a reference based on a partitioned decl replace the
311 base with an INDIRECT_REF of the pointer representative we
312 created during stack slot partitioning. */
313 if (TREE_CODE (base
) == VAR_DECL
314 && ! TREE_STATIC (base
)
315 && cfun
->gimple_df
->decls_to_pointers
!= NULL
)
318 namep
= pointer_map_contains (cfun
->gimple_df
->decls_to_pointers
, base
);
320 ref
->base
= build_simple_mem_ref (*(tree
*)namep
);
322 else if (TREE_CODE (base
) == TARGET_MEM_REF
323 && TREE_CODE (TMR_BASE (base
)) == ADDR_EXPR
324 && TREE_CODE (TREE_OPERAND (TMR_BASE (base
), 0)) == VAR_DECL
325 && ! TREE_STATIC (TREE_OPERAND (TMR_BASE (base
), 0))
326 && cfun
->gimple_df
->decls_to_pointers
!= NULL
)
329 namep
= pointer_map_contains (cfun
->gimple_df
->decls_to_pointers
,
330 TREE_OPERAND (TMR_BASE (base
), 0));
332 ref
->base
= build_simple_mem_ref (*(tree
*)namep
);
335 ref
->ref_alias_set
= MEM_ALIAS_SET (mem
);
337 /* If MEM_OFFSET or MEM_SIZE are unknown we have to punt.
338 Keep points-to related information though. */
339 if (!MEM_OFFSET_KNOWN_P (mem
)
340 || !MEM_SIZE_KNOWN_P (mem
))
342 ref
->ref
= NULL_TREE
;
349 /* If the base decl is a parameter we can have negative MEM_OFFSET in
350 case of promoted subregs on bigendian targets. Trust the MEM_EXPR
352 if (MEM_OFFSET (mem
) < 0
353 && (MEM_SIZE (mem
) + MEM_OFFSET (mem
)) * BITS_PER_UNIT
== ref
->size
)
356 ref
->offset
+= MEM_OFFSET (mem
) * BITS_PER_UNIT
;
357 ref
->size
= MEM_SIZE (mem
) * BITS_PER_UNIT
;
359 /* The MEM may extend into adjacent fields, so adjust max_size if
361 if (ref
->max_size
!= -1
362 && ref
->size
> ref
->max_size
)
363 ref
->max_size
= ref
->size
;
365 /* If MEM_OFFSET and MEM_SIZE get us outside of the base object of
366 the MEM_EXPR punt. This happens for STRICT_ALIGNMENT targets a lot. */
367 if (MEM_EXPR (mem
) != get_spill_slot_decl (false)
369 || (DECL_P (ref
->base
)
370 && (!host_integerp (DECL_SIZE (ref
->base
), 1)
371 || (TREE_INT_CST_LOW (DECL_SIZE ((ref
->base
)))
372 < (unsigned HOST_WIDE_INT
)(ref
->offset
+ ref
->size
))))))
378 /* Query the alias-oracle on whether the two memory rtx X and MEM may
379 alias. If TBAA_P is set also apply TBAA. Returns true if the
380 two rtxen may alias, false otherwise. */
383 rtx_refs_may_alias_p (const_rtx x
, const_rtx mem
, bool tbaa_p
)
387 if (!ao_ref_from_mem (&ref1
, x
)
388 || !ao_ref_from_mem (&ref2
, mem
))
391 return refs_may_alias_p_1 (&ref1
, &ref2
,
393 && MEM_ALIAS_SET (x
) != 0
394 && MEM_ALIAS_SET (mem
) != 0);
397 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
398 such an entry, or NULL otherwise. */
400 static inline alias_set_entry
401 get_alias_set_entry (alias_set_type alias_set
)
403 return VEC_index (alias_set_entry
, alias_sets
, alias_set
);
406 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
407 the two MEMs cannot alias each other. */
410 mems_in_disjoint_alias_sets_p (const_rtx mem1
, const_rtx mem2
)
412 /* Perform a basic sanity check. Namely, that there are no alias sets
413 if we're not using strict aliasing. This helps to catch bugs
414 whereby someone uses PUT_CODE, but doesn't clear MEM_ALIAS_SET, or
415 where a MEM is allocated in some way other than by the use of
416 gen_rtx_MEM, and the MEM_ALIAS_SET is not cleared. If we begin to
417 use alias sets to indicate that spilled registers cannot alias each
418 other, we might need to remove this check. */
419 gcc_assert (flag_strict_aliasing
420 || (!MEM_ALIAS_SET (mem1
) && !MEM_ALIAS_SET (mem2
)));
422 return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1
), MEM_ALIAS_SET (mem2
));
425 /* Insert the NODE into the splay tree given by DATA. Used by
426 record_alias_subset via splay_tree_foreach. */
429 insert_subset_children (splay_tree_node node
, void *data
)
431 splay_tree_insert ((splay_tree
) data
, node
->key
, node
->value
);
436 /* Return true if the first alias set is a subset of the second. */
439 alias_set_subset_of (alias_set_type set1
, alias_set_type set2
)
443 /* Everything is a subset of the "aliases everything" set. */
447 /* Otherwise, check if set1 is a subset of set2. */
448 ase
= get_alias_set_entry (set2
);
450 && (ase
->has_zero_child
451 || splay_tree_lookup (ase
->children
,
452 (splay_tree_key
) set1
)))
457 /* Return 1 if the two specified alias sets may conflict. */
460 alias_sets_conflict_p (alias_set_type set1
, alias_set_type set2
)
465 if (alias_sets_must_conflict_p (set1
, set2
))
468 /* See if the first alias set is a subset of the second. */
469 ase
= get_alias_set_entry (set1
);
471 && (ase
->has_zero_child
472 || splay_tree_lookup (ase
->children
,
473 (splay_tree_key
) set2
)))
476 /* Now do the same, but with the alias sets reversed. */
477 ase
= get_alias_set_entry (set2
);
479 && (ase
->has_zero_child
480 || splay_tree_lookup (ase
->children
,
481 (splay_tree_key
) set1
)))
484 /* The two alias sets are distinct and neither one is the
485 child of the other. Therefore, they cannot conflict. */
489 /* Return 1 if the two specified alias sets will always conflict. */
492 alias_sets_must_conflict_p (alias_set_type set1
, alias_set_type set2
)
494 if (set1
== 0 || set2
== 0 || set1
== set2
)
500 /* Return 1 if any MEM object of type T1 will always conflict (using the
501 dependency routines in this file) with any MEM object of type T2.
502 This is used when allocating temporary storage. If T1 and/or T2 are
503 NULL_TREE, it means we know nothing about the storage. */
506 objects_must_conflict_p (tree t1
, tree t2
)
508 alias_set_type set1
, set2
;
510 /* If neither has a type specified, we don't know if they'll conflict
511 because we may be using them to store objects of various types, for
512 example the argument and local variables areas of inlined functions. */
513 if (t1
== 0 && t2
== 0)
516 /* If they are the same type, they must conflict. */
518 /* Likewise if both are volatile. */
519 || (t1
!= 0 && TYPE_VOLATILE (t1
) && t2
!= 0 && TYPE_VOLATILE (t2
)))
522 set1
= t1
? get_alias_set (t1
) : 0;
523 set2
= t2
? get_alias_set (t2
) : 0;
525 /* We can't use alias_sets_conflict_p because we must make sure
526 that every subtype of t1 will conflict with every subtype of
527 t2 for which a pair of subobjects of these respective subtypes
528 overlaps on the stack. */
529 return alias_sets_must_conflict_p (set1
, set2
);
532 /* Return true if all nested component references handled by
533 get_inner_reference in T are such that we should use the alias set
534 provided by the object at the heart of T.
536 This is true for non-addressable components (which don't have their
537 own alias set), as well as components of objects in alias set zero.
538 This later point is a special case wherein we wish to override the
539 alias set used by the component, but we don't have per-FIELD_DECL
540 assignable alias sets. */
543 component_uses_parent_alias_set (const_tree t
)
547 /* If we're at the end, it vacuously uses its own alias set. */
548 if (!handled_component_p (t
))
551 switch (TREE_CODE (t
))
554 if (DECL_NONADDRESSABLE_P (TREE_OPERAND (t
, 1)))
559 case ARRAY_RANGE_REF
:
560 if (TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t
, 0))))
569 /* Bitfields and casts are never addressable. */
573 t
= TREE_OPERAND (t
, 0);
574 if (get_alias_set (TREE_TYPE (t
)) == 0)
579 /* Return the alias set for the memory pointed to by T, which may be
580 either a type or an expression. Return -1 if there is nothing
581 special about dereferencing T. */
583 static alias_set_type
584 get_deref_alias_set_1 (tree t
)
586 /* If we're not doing any alias analysis, just assume everything
587 aliases everything else. */
588 if (!flag_strict_aliasing
)
591 /* All we care about is the type. */
595 /* If we have an INDIRECT_REF via a void pointer, we don't
596 know anything about what that might alias. Likewise if the
597 pointer is marked that way. */
598 if (TREE_CODE (TREE_TYPE (t
)) == VOID_TYPE
599 || TYPE_REF_CAN_ALIAS_ALL (t
))
605 /* Return the alias set for the memory pointed to by T, which may be
606 either a type or an expression. */
609 get_deref_alias_set (tree t
)
611 alias_set_type set
= get_deref_alias_set_1 (t
);
613 /* Fall back to the alias-set of the pointed-to type. */
618 set
= get_alias_set (TREE_TYPE (t
));
624 /* Return the alias set for T, which may be either a type or an
625 expression. Call language-specific routine for help, if needed. */
628 get_alias_set (tree t
)
632 /* If we're not doing any alias analysis, just assume everything
633 aliases everything else. Also return 0 if this or its type is
635 if (! flag_strict_aliasing
|| t
== error_mark_node
637 && (TREE_TYPE (t
) == 0 || TREE_TYPE (t
) == error_mark_node
)))
640 /* We can be passed either an expression or a type. This and the
641 language-specific routine may make mutually-recursive calls to each other
642 to figure out what to do. At each juncture, we see if this is a tree
643 that the language may need to handle specially. First handle things that
649 /* Give the language a chance to do something with this tree
650 before we look at it. */
652 set
= lang_hooks
.get_alias_set (t
);
656 /* Get the base object of the reference. */
658 while (handled_component_p (inner
))
660 /* If there is a VIEW_CONVERT_EXPR in the chain we cannot use
661 the type of any component references that wrap it to
662 determine the alias-set. */
663 if (TREE_CODE (inner
) == VIEW_CONVERT_EXPR
)
664 t
= TREE_OPERAND (inner
, 0);
665 inner
= TREE_OPERAND (inner
, 0);
668 /* Handle pointer dereferences here, they can override the
670 if (INDIRECT_REF_P (inner
))
672 set
= get_deref_alias_set_1 (TREE_OPERAND (inner
, 0));
676 else if (TREE_CODE (inner
) == TARGET_MEM_REF
)
677 return get_deref_alias_set (TMR_OFFSET (inner
));
678 else if (TREE_CODE (inner
) == MEM_REF
)
680 set
= get_deref_alias_set_1 (TREE_OPERAND (inner
, 1));
685 /* If the innermost reference is a MEM_REF that has a
686 conversion embedded treat it like a VIEW_CONVERT_EXPR above,
687 using the memory access type for determining the alias-set. */
688 if (TREE_CODE (inner
) == MEM_REF
689 && TYPE_MAIN_VARIANT (TREE_TYPE (inner
))
691 (TREE_TYPE (TREE_TYPE (TREE_OPERAND (inner
, 1)))))
692 return get_deref_alias_set (TREE_OPERAND (inner
, 1));
694 /* Otherwise, pick up the outermost object that we could have a pointer
695 to, processing conversions as above. */
696 while (component_uses_parent_alias_set (t
))
698 t
= TREE_OPERAND (t
, 0);
702 /* If we've already determined the alias set for a decl, just return
703 it. This is necessary for C++ anonymous unions, whose component
704 variables don't look like union members (boo!). */
705 if (TREE_CODE (t
) == VAR_DECL
706 && DECL_RTL_SET_P (t
) && MEM_P (DECL_RTL (t
)))
707 return MEM_ALIAS_SET (DECL_RTL (t
));
709 /* Now all we care about is the type. */
713 /* Variant qualifiers don't affect the alias set, so get the main
715 t
= TYPE_MAIN_VARIANT (t
);
717 /* Always use the canonical type as well. If this is a type that
718 requires structural comparisons to identify compatible types
719 use alias set zero. */
720 if (TYPE_STRUCTURAL_EQUALITY_P (t
))
722 /* Allow the language to specify another alias set for this
724 set
= lang_hooks
.get_alias_set (t
);
730 t
= TYPE_CANONICAL (t
);
732 /* The canonical type should not require structural equality checks. */
733 gcc_checking_assert (!TYPE_STRUCTURAL_EQUALITY_P (t
));
735 /* If this is a type with a known alias set, return it. */
736 if (TYPE_ALIAS_SET_KNOWN_P (t
))
737 return TYPE_ALIAS_SET (t
);
739 /* We don't want to set TYPE_ALIAS_SET for incomplete types. */
740 if (!COMPLETE_TYPE_P (t
))
742 /* For arrays with unknown size the conservative answer is the
743 alias set of the element type. */
744 if (TREE_CODE (t
) == ARRAY_TYPE
)
745 return get_alias_set (TREE_TYPE (t
));
747 /* But return zero as a conservative answer for incomplete types. */
751 /* See if the language has special handling for this type. */
752 set
= lang_hooks
.get_alias_set (t
);
756 /* There are no objects of FUNCTION_TYPE, so there's no point in
757 using up an alias set for them. (There are, of course, pointers
758 and references to functions, but that's different.) */
759 else if (TREE_CODE (t
) == FUNCTION_TYPE
|| TREE_CODE (t
) == METHOD_TYPE
)
762 /* Unless the language specifies otherwise, let vector types alias
763 their components. This avoids some nasty type punning issues in
764 normal usage. And indeed lets vectors be treated more like an
766 else if (TREE_CODE (t
) == VECTOR_TYPE
)
767 set
= get_alias_set (TREE_TYPE (t
));
769 /* Unless the language specifies otherwise, treat array types the
770 same as their components. This avoids the asymmetry we get
771 through recording the components. Consider accessing a
772 character(kind=1) through a reference to a character(kind=1)[1:1].
773 Or consider if we want to assign integer(kind=4)[0:D.1387] and
774 integer(kind=4)[4] the same alias set or not.
775 Just be pragmatic here and make sure the array and its element
776 type get the same alias set assigned. */
777 else if (TREE_CODE (t
) == ARRAY_TYPE
&& !TYPE_NONALIASED_COMPONENT (t
))
778 set
= get_alias_set (TREE_TYPE (t
));
780 /* From the former common C and C++ langhook implementation:
782 Unfortunately, there is no canonical form of a pointer type.
783 In particular, if we have `typedef int I', then `int *', and
784 `I *' are different types. So, we have to pick a canonical
785 representative. We do this below.
787 Technically, this approach is actually more conservative that
788 it needs to be. In particular, `const int *' and `int *'
789 should be in different alias sets, according to the C and C++
790 standard, since their types are not the same, and so,
791 technically, an `int **' and `const int **' cannot point at
794 But, the standard is wrong. In particular, this code is
799 const int* const* cipp = ipp;
800 And, it doesn't make sense for that to be legal unless you
801 can dereference IPP and CIPP. So, we ignore cv-qualifiers on
802 the pointed-to types. This issue has been reported to the
805 In addition to the above canonicalization issue, with LTO
806 we should also canonicalize `T (*)[]' to `T *' avoiding
807 alias issues with pointer-to element types and pointer-to
810 Likewise we need to deal with the situation of incomplete
811 pointed-to types and make `*(struct X **)&a' and
812 `*(struct X {} **)&a' alias. Otherwise we will have to
813 guarantee that all pointer-to incomplete type variants
814 will be replaced by pointer-to complete type variants if
817 With LTO the convenient situation of using `void *' to
818 access and store any pointer type will also become
819 more apparent (and `void *' is just another pointer-to
820 incomplete type). Assigning alias-set zero to `void *'
821 and all pointer-to incomplete types is a not appealing
822 solution. Assigning an effective alias-set zero only
823 affecting pointers might be - by recording proper subset
824 relationships of all pointer alias-sets.
826 Pointer-to function types are another grey area which
827 needs caution. Globbing them all into one alias-set
828 or the above effective zero set would work.
830 For now just assign the same alias-set to all pointers.
831 That's simple and avoids all the above problems. */
832 else if (POINTER_TYPE_P (t
)
833 && t
!= ptr_type_node
)
834 set
= get_alias_set (ptr_type_node
);
836 /* Otherwise make a new alias set for this type. */
839 /* Each canonical type gets its own alias set, so canonical types
840 shouldn't form a tree. It doesn't really matter for types
841 we handle specially above, so only check it where it possibly
842 would result in a bogus alias set. */
843 gcc_checking_assert (TYPE_CANONICAL (t
) == t
);
845 set
= new_alias_set ();
848 TYPE_ALIAS_SET (t
) = set
;
850 /* If this is an aggregate type or a complex type, we must record any
851 component aliasing information. */
852 if (AGGREGATE_TYPE_P (t
) || TREE_CODE (t
) == COMPLEX_TYPE
)
853 record_component_aliases (t
);
858 /* Return a brand-new alias set. */
863 if (flag_strict_aliasing
)
866 VEC_safe_push (alias_set_entry
, gc
, alias_sets
, 0);
867 VEC_safe_push (alias_set_entry
, gc
, alias_sets
, 0);
868 return VEC_length (alias_set_entry
, alias_sets
) - 1;
874 /* Indicate that things in SUBSET can alias things in SUPERSET, but that
875 not everything that aliases SUPERSET also aliases SUBSET. For example,
876 in C, a store to an `int' can alias a load of a structure containing an
877 `int', and vice versa. But it can't alias a load of a 'double' member
878 of the same structure. Here, the structure would be the SUPERSET and
879 `int' the SUBSET. This relationship is also described in the comment at
880 the beginning of this file.
882 This function should be called only once per SUPERSET/SUBSET pair.
884 It is illegal for SUPERSET to be zero; everything is implicitly a
885 subset of alias set zero. */
888 record_alias_subset (alias_set_type superset
, alias_set_type subset
)
890 alias_set_entry superset_entry
;
891 alias_set_entry subset_entry
;
893 /* It is possible in complex type situations for both sets to be the same,
894 in which case we can ignore this operation. */
895 if (superset
== subset
)
898 gcc_assert (superset
);
900 superset_entry
= get_alias_set_entry (superset
);
901 if (superset_entry
== 0)
903 /* Create an entry for the SUPERSET, so that we have a place to
904 attach the SUBSET. */
905 superset_entry
= ggc_alloc_cleared_alias_set_entry_d ();
906 superset_entry
->alias_set
= superset
;
907 superset_entry
->children
908 = splay_tree_new_ggc (splay_tree_compare_ints
,
909 ggc_alloc_splay_tree_scalar_scalar_splay_tree_s
,
910 ggc_alloc_splay_tree_scalar_scalar_splay_tree_node_s
);
911 superset_entry
->has_zero_child
= 0;
912 VEC_replace (alias_set_entry
, alias_sets
, superset
, superset_entry
);
916 superset_entry
->has_zero_child
= 1;
919 subset_entry
= get_alias_set_entry (subset
);
920 /* If there is an entry for the subset, enter all of its children
921 (if they are not already present) as children of the SUPERSET. */
924 if (subset_entry
->has_zero_child
)
925 superset_entry
->has_zero_child
= 1;
927 splay_tree_foreach (subset_entry
->children
, insert_subset_children
,
928 superset_entry
->children
);
931 /* Enter the SUBSET itself as a child of the SUPERSET. */
932 splay_tree_insert (superset_entry
->children
,
933 (splay_tree_key
) subset
, 0);
937 /* Record that component types of TYPE, if any, are part of that type for
938 aliasing purposes. For record types, we only record component types
939 for fields that are not marked non-addressable. For array types, we
940 only record the component type if it is not marked non-aliased. */
943 record_component_aliases (tree type
)
945 alias_set_type superset
= get_alias_set (type
);
951 switch (TREE_CODE (type
))
955 case QUAL_UNION_TYPE
:
956 /* Recursively record aliases for the base classes, if there are any. */
957 if (TYPE_BINFO (type
))
960 tree binfo
, base_binfo
;
962 for (binfo
= TYPE_BINFO (type
), i
= 0;
963 BINFO_BASE_ITERATE (binfo
, i
, base_binfo
); i
++)
964 record_alias_subset (superset
,
965 get_alias_set (BINFO_TYPE (base_binfo
)));
967 for (field
= TYPE_FIELDS (type
); field
!= 0; field
= DECL_CHAIN (field
))
968 if (TREE_CODE (field
) == FIELD_DECL
&& !DECL_NONADDRESSABLE_P (field
))
969 record_alias_subset (superset
, get_alias_set (TREE_TYPE (field
)));
973 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
976 /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their
984 /* Allocate an alias set for use in storing and reading from the varargs
987 static GTY(()) alias_set_type varargs_set
= -1;
990 get_varargs_alias_set (void)
993 /* We now lower VA_ARG_EXPR, and there's currently no way to attach the
994 varargs alias set to an INDIRECT_REF (FIXME!), so we can't
995 consistently use the varargs alias set for loads from the varargs
996 area. So don't use it anywhere. */
999 if (varargs_set
== -1)
1000 varargs_set
= new_alias_set ();
1006 /* Likewise, but used for the fixed portions of the frame, e.g., register
1009 static GTY(()) alias_set_type frame_set
= -1;
1012 get_frame_alias_set (void)
1014 if (frame_set
== -1)
1015 frame_set
= new_alias_set ();
1020 /* Create a new, unique base with id ID. */
1023 unique_base_value (HOST_WIDE_INT id
)
1025 return gen_rtx_ADDRESS (Pmode
, id
);
1028 /* Return true if accesses based on any other base value cannot alias
1029 those based on X. */
1032 unique_base_value_p (rtx x
)
1034 return GET_CODE (x
) == ADDRESS
&& GET_MODE (x
) == Pmode
;
1037 /* Return true if X is known to be a base value. */
1040 known_base_value_p (rtx x
)
1042 switch (GET_CODE (x
))
1049 /* Arguments may or may not be bases; we don't know for sure. */
1050 return GET_MODE (x
) != VOIDmode
;
1057 /* Inside SRC, the source of a SET, find a base address. */
1060 find_base_value (rtx src
)
1064 #if defined (FIND_BASE_TERM)
1065 /* Try machine-dependent ways to find the base term. */
1066 src
= FIND_BASE_TERM (src
);
1069 switch (GET_CODE (src
))
1076 regno
= REGNO (src
);
1077 /* At the start of a function, argument registers have known base
1078 values which may be lost later. Returning an ADDRESS
1079 expression here allows optimization based on argument values
1080 even when the argument registers are used for other purposes. */
1081 if (regno
< FIRST_PSEUDO_REGISTER
&& copying_arguments
)
1082 return new_reg_base_value
[regno
];
1084 /* If a pseudo has a known base value, return it. Do not do this
1085 for non-fixed hard regs since it can result in a circular
1086 dependency chain for registers which have values at function entry.
1088 The test above is not sufficient because the scheduler may move
1089 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
1090 if ((regno
>= FIRST_PSEUDO_REGISTER
|| fixed_regs
[regno
])
1091 && regno
< VEC_length (rtx
, reg_base_value
))
1093 /* If we're inside init_alias_analysis, use new_reg_base_value
1094 to reduce the number of relaxation iterations. */
1095 if (new_reg_base_value
&& new_reg_base_value
[regno
]
1096 && DF_REG_DEF_COUNT (regno
) == 1)
1097 return new_reg_base_value
[regno
];
1099 if (VEC_index (rtx
, reg_base_value
, regno
))
1100 return VEC_index (rtx
, reg_base_value
, regno
);
1106 /* Check for an argument passed in memory. Only record in the
1107 copying-arguments block; it is too hard to track changes
1109 if (copying_arguments
1110 && (XEXP (src
, 0) == arg_pointer_rtx
1111 || (GET_CODE (XEXP (src
, 0)) == PLUS
1112 && XEXP (XEXP (src
, 0), 0) == arg_pointer_rtx
)))
1113 return arg_base_value
;
1117 src
= XEXP (src
, 0);
1118 if (GET_CODE (src
) != PLUS
&& GET_CODE (src
) != MINUS
)
1121 /* ... fall through ... */
1126 rtx temp
, src_0
= XEXP (src
, 0), src_1
= XEXP (src
, 1);
1128 /* If either operand is a REG that is a known pointer, then it
1130 if (REG_P (src_0
) && REG_POINTER (src_0
))
1131 return find_base_value (src_0
);
1132 if (REG_P (src_1
) && REG_POINTER (src_1
))
1133 return find_base_value (src_1
);
1135 /* If either operand is a REG, then see if we already have
1136 a known value for it. */
1139 temp
= find_base_value (src_0
);
1146 temp
= find_base_value (src_1
);
1151 /* If either base is named object or a special address
1152 (like an argument or stack reference), then use it for the
1154 if (src_0
!= 0 && known_base_value_p (src_0
))
1157 if (src_1
!= 0 && known_base_value_p (src_1
))
1160 /* Guess which operand is the base address:
1161 If either operand is a symbol, then it is the base. If
1162 either operand is a CONST_INT, then the other is the base. */
1163 if (CONST_INT_P (src_1
) || CONSTANT_P (src_0
))
1164 return find_base_value (src_0
);
1165 else if (CONST_INT_P (src_0
) || CONSTANT_P (src_1
))
1166 return find_base_value (src_1
);
1172 /* The standard form is (lo_sum reg sym) so look only at the
1174 return find_base_value (XEXP (src
, 1));
1177 /* If the second operand is constant set the base
1178 address to the first operand. */
1179 if (CONST_INT_P (XEXP (src
, 1)) && INTVAL (XEXP (src
, 1)) != 0)
1180 return find_base_value (XEXP (src
, 0));
1184 /* As we do not know which address space the pointer is referring to, we can
1185 handle this only if the target does not support different pointer or
1186 address modes depending on the address space. */
1187 if (!target_default_pointer_address_modes_p ())
1189 if (GET_MODE_SIZE (GET_MODE (src
)) < GET_MODE_SIZE (Pmode
))
1199 return find_base_value (XEXP (src
, 0));
1202 case SIGN_EXTEND
: /* used for NT/Alpha pointers */
1203 /* As we do not know which address space the pointer is referring to, we can
1204 handle this only if the target does not support different pointer or
1205 address modes depending on the address space. */
1206 if (!target_default_pointer_address_modes_p ())
1210 rtx temp
= find_base_value (XEXP (src
, 0));
1212 if (temp
!= 0 && CONSTANT_P (temp
))
1213 temp
= convert_memory_address (Pmode
, temp
);
1225 /* Called from init_alias_analysis indirectly through note_stores,
1226 or directly if DEST is a register with a REG_NOALIAS note attached.
1227 SET is null in the latter case. */
1229 /* While scanning insns to find base values, reg_seen[N] is nonzero if
1230 register N has been set in this function. */
1231 static char *reg_seen
;
1234 record_set (rtx dest
, const_rtx set
, void *data ATTRIBUTE_UNUSED
)
1243 regno
= REGNO (dest
);
1245 gcc_checking_assert (regno
< VEC_length (rtx
, reg_base_value
));
1247 /* If this spans multiple hard registers, then we must indicate that every
1248 register has an unusable value. */
1249 if (regno
< FIRST_PSEUDO_REGISTER
)
1250 n
= hard_regno_nregs
[regno
][GET_MODE (dest
)];
1257 reg_seen
[regno
+ n
] = 1;
1258 new_reg_base_value
[regno
+ n
] = 0;
1265 /* A CLOBBER wipes out any old value but does not prevent a previously
1266 unset register from acquiring a base address (i.e. reg_seen is not
1268 if (GET_CODE (set
) == CLOBBER
)
1270 new_reg_base_value
[regno
] = 0;
1273 src
= SET_SRC (set
);
1277 /* There's a REG_NOALIAS note against DEST. */
1278 if (reg_seen
[regno
])
1280 new_reg_base_value
[regno
] = 0;
1283 reg_seen
[regno
] = 1;
1284 new_reg_base_value
[regno
] = unique_base_value (unique_id
++);
1288 /* If this is not the first set of REGNO, see whether the new value
1289 is related to the old one. There are two cases of interest:
1291 (1) The register might be assigned an entirely new value
1292 that has the same base term as the original set.
1294 (2) The set might be a simple self-modification that
1295 cannot change REGNO's base value.
1297 If neither case holds, reject the original base value as invalid.
1298 Note that the following situation is not detected:
1300 extern int x, y; int *p = &x; p += (&y-&x);
1302 ANSI C does not allow computing the difference of addresses
1303 of distinct top level objects. */
1304 if (new_reg_base_value
[regno
] != 0
1305 && find_base_value (src
) != new_reg_base_value
[regno
])
1306 switch (GET_CODE (src
))
1310 if (XEXP (src
, 0) != dest
&& XEXP (src
, 1) != dest
)
1311 new_reg_base_value
[regno
] = 0;
1314 /* If the value we add in the PLUS is also a valid base value,
1315 this might be the actual base value, and the original value
1318 rtx other
= NULL_RTX
;
1320 if (XEXP (src
, 0) == dest
)
1321 other
= XEXP (src
, 1);
1322 else if (XEXP (src
, 1) == dest
)
1323 other
= XEXP (src
, 0);
1325 if (! other
|| find_base_value (other
))
1326 new_reg_base_value
[regno
] = 0;
1330 if (XEXP (src
, 0) != dest
|| !CONST_INT_P (XEXP (src
, 1)))
1331 new_reg_base_value
[regno
] = 0;
1334 new_reg_base_value
[regno
] = 0;
1337 /* If this is the first set of a register, record the value. */
1338 else if ((regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
1339 && ! reg_seen
[regno
] && new_reg_base_value
[regno
] == 0)
1340 new_reg_base_value
[regno
] = find_base_value (src
);
1342 reg_seen
[regno
] = 1;
1345 /* Return REG_BASE_VALUE for REGNO. Selective scheduler uses this to avoid
1346 using hard registers with non-null REG_BASE_VALUE for renaming. */
1348 get_reg_base_value (unsigned int regno
)
1350 return VEC_index (rtx
, reg_base_value
, regno
);
1353 /* If a value is known for REGNO, return it. */
1356 get_reg_known_value (unsigned int regno
)
1358 if (regno
>= FIRST_PSEUDO_REGISTER
)
1360 regno
-= FIRST_PSEUDO_REGISTER
;
1361 if (regno
< VEC_length (rtx
, reg_known_value
))
1362 return VEC_index (rtx
, reg_known_value
, regno
);
1370 set_reg_known_value (unsigned int regno
, rtx val
)
1372 if (regno
>= FIRST_PSEUDO_REGISTER
)
1374 regno
-= FIRST_PSEUDO_REGISTER
;
1375 if (regno
< VEC_length (rtx
, reg_known_value
))
1376 VEC_replace (rtx
, reg_known_value
, regno
, val
);
1380 /* Similarly for reg_known_equiv_p. */
1383 get_reg_known_equiv_p (unsigned int regno
)
1385 if (regno
>= FIRST_PSEUDO_REGISTER
)
1387 regno
-= FIRST_PSEUDO_REGISTER
;
1388 if (regno
< VEC_length (rtx
, reg_known_value
))
1389 return TEST_BIT (reg_known_equiv_p
, regno
);
1395 set_reg_known_equiv_p (unsigned int regno
, bool val
)
1397 if (regno
>= FIRST_PSEUDO_REGISTER
)
1399 regno
-= FIRST_PSEUDO_REGISTER
;
1400 if (regno
< VEC_length (rtx
, reg_known_value
))
1403 SET_BIT (reg_known_equiv_p
, regno
);
1405 RESET_BIT (reg_known_equiv_p
, regno
);
1411 /* Returns a canonical version of X, from the point of view alias
1412 analysis. (For example, if X is a MEM whose address is a register,
1413 and the register has a known value (say a SYMBOL_REF), then a MEM
1414 whose address is the SYMBOL_REF is returned.) */
1419 /* Recursively look for equivalences. */
1420 if (REG_P (x
) && REGNO (x
) >= FIRST_PSEUDO_REGISTER
)
1422 rtx t
= get_reg_known_value (REGNO (x
));
1426 return canon_rtx (t
);
1429 if (GET_CODE (x
) == PLUS
)
1431 rtx x0
= canon_rtx (XEXP (x
, 0));
1432 rtx x1
= canon_rtx (XEXP (x
, 1));
1434 if (x0
!= XEXP (x
, 0) || x1
!= XEXP (x
, 1))
1436 if (CONST_INT_P (x0
))
1437 return plus_constant (GET_MODE (x
), x1
, INTVAL (x0
));
1438 else if (CONST_INT_P (x1
))
1439 return plus_constant (GET_MODE (x
), x0
, INTVAL (x1
));
1440 return gen_rtx_PLUS (GET_MODE (x
), x0
, x1
);
1444 /* This gives us much better alias analysis when called from
1445 the loop optimizer. Note we want to leave the original
1446 MEM alone, but need to return the canonicalized MEM with
1447 all the flags with their original values. */
1449 x
= replace_equiv_address_nv (x
, canon_rtx (XEXP (x
, 0)));
1454 /* Return 1 if X and Y are identical-looking rtx's.
1455 Expect that X and Y has been already canonicalized.
1457 We use the data in reg_known_value above to see if two registers with
1458 different numbers are, in fact, equivalent. */
1461 rtx_equal_for_memref_p (const_rtx x
, const_rtx y
)
1468 if (x
== 0 && y
== 0)
1470 if (x
== 0 || y
== 0)
1476 code
= GET_CODE (x
);
1477 /* Rtx's of different codes cannot be equal. */
1478 if (code
!= GET_CODE (y
))
1481 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1482 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1484 if (GET_MODE (x
) != GET_MODE (y
))
1487 /* Some RTL can be compared without a recursive examination. */
1491 return REGNO (x
) == REGNO (y
);
1494 return XEXP (x
, 0) == XEXP (y
, 0);
1497 return XSTR (x
, 0) == XSTR (y
, 0);
1503 /* There's no need to compare the contents of CONST_DOUBLEs or
1504 CONST_INTs because pointer equality is a good enough
1505 comparison for these nodes. */
1512 /* canon_rtx knows how to handle plus. No need to canonicalize. */
1514 return ((rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0))
1515 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 1)))
1516 || (rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 1))
1517 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 0))));
1518 /* For commutative operations, the RTX match if the operand match in any
1519 order. Also handle the simple binary and unary cases without a loop. */
1520 if (COMMUTATIVE_P (x
))
1522 rtx xop0
= canon_rtx (XEXP (x
, 0));
1523 rtx yop0
= canon_rtx (XEXP (y
, 0));
1524 rtx yop1
= canon_rtx (XEXP (y
, 1));
1526 return ((rtx_equal_for_memref_p (xop0
, yop0
)
1527 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop1
))
1528 || (rtx_equal_for_memref_p (xop0
, yop1
)
1529 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop0
)));
1531 else if (NON_COMMUTATIVE_P (x
))
1533 return (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1534 canon_rtx (XEXP (y
, 0)))
1535 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)),
1536 canon_rtx (XEXP (y
, 1))));
1538 else if (UNARY_P (x
))
1539 return rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1540 canon_rtx (XEXP (y
, 0)));
1542 /* Compare the elements. If any pair of corresponding elements
1543 fail to match, return 0 for the whole things.
1545 Limit cases to types which actually appear in addresses. */
1547 fmt
= GET_RTX_FORMAT (code
);
1548 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1553 if (XINT (x
, i
) != XINT (y
, i
))
1558 /* Two vectors must have the same length. */
1559 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1562 /* And the corresponding elements must match. */
1563 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1564 if (rtx_equal_for_memref_p (canon_rtx (XVECEXP (x
, i
, j
)),
1565 canon_rtx (XVECEXP (y
, i
, j
))) == 0)
1570 if (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, i
)),
1571 canon_rtx (XEXP (y
, i
))) == 0)
1575 /* This can happen for asm operands. */
1577 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1581 /* This can happen for an asm which clobbers memory. */
1585 /* It is believed that rtx's at this level will never
1586 contain anything but integers and other rtx's,
1587 except for within LABEL_REFs and SYMBOL_REFs. */
1596 find_base_term (rtx x
)
1599 struct elt_loc_list
*l
, *f
;
1602 #if defined (FIND_BASE_TERM)
1603 /* Try machine-dependent ways to find the base term. */
1604 x
= FIND_BASE_TERM (x
);
1607 switch (GET_CODE (x
))
1610 return REG_BASE_VALUE (x
);
1613 /* As we do not know which address space the pointer is referring to, we can
1614 handle this only if the target does not support different pointer or
1615 address modes depending on the address space. */
1616 if (!target_default_pointer_address_modes_p ())
1618 if (GET_MODE_SIZE (GET_MODE (x
)) < GET_MODE_SIZE (Pmode
))
1628 return find_base_term (XEXP (x
, 0));
1631 case SIGN_EXTEND
: /* Used for Alpha/NT pointers */
1632 /* As we do not know which address space the pointer is referring to, we can
1633 handle this only if the target does not support different pointer or
1634 address modes depending on the address space. */
1635 if (!target_default_pointer_address_modes_p ())
1639 rtx temp
= find_base_term (XEXP (x
, 0));
1641 if (temp
!= 0 && CONSTANT_P (temp
))
1642 temp
= convert_memory_address (Pmode
, temp
);
1648 val
= CSELIB_VAL_PTR (x
);
1655 /* Temporarily reset val->locs to avoid infinite recursion. */
1658 for (l
= f
; l
; l
= l
->next
)
1659 if (GET_CODE (l
->loc
) == VALUE
1660 && CSELIB_VAL_PTR (l
->loc
)->locs
1661 && !CSELIB_VAL_PTR (l
->loc
)->locs
->next
1662 && CSELIB_VAL_PTR (l
->loc
)->locs
->loc
== x
)
1664 else if ((ret
= find_base_term (l
->loc
)) != 0)
1671 /* The standard form is (lo_sum reg sym) so look only at the
1673 return find_base_term (XEXP (x
, 1));
1677 if (GET_CODE (x
) != PLUS
&& GET_CODE (x
) != MINUS
)
1683 rtx tmp1
= XEXP (x
, 0);
1684 rtx tmp2
= XEXP (x
, 1);
1686 /* This is a little bit tricky since we have to determine which of
1687 the two operands represents the real base address. Otherwise this
1688 routine may return the index register instead of the base register.
1690 That may cause us to believe no aliasing was possible, when in
1691 fact aliasing is possible.
1693 We use a few simple tests to guess the base register. Additional
1694 tests can certainly be added. For example, if one of the operands
1695 is a shift or multiply, then it must be the index register and the
1696 other operand is the base register. */
1698 if (tmp1
== pic_offset_table_rtx
&& CONSTANT_P (tmp2
))
1699 return find_base_term (tmp2
);
1701 /* If either operand is known to be a pointer, then use it
1702 to determine the base term. */
1703 if (REG_P (tmp1
) && REG_POINTER (tmp1
))
1705 rtx base
= find_base_term (tmp1
);
1710 if (REG_P (tmp2
) && REG_POINTER (tmp2
))
1712 rtx base
= find_base_term (tmp2
);
1717 /* Neither operand was known to be a pointer. Go ahead and find the
1718 base term for both operands. */
1719 tmp1
= find_base_term (tmp1
);
1720 tmp2
= find_base_term (tmp2
);
1722 /* If either base term is named object or a special address
1723 (like an argument or stack reference), then use it for the
1725 if (tmp1
!= 0 && known_base_value_p (tmp1
))
1728 if (tmp2
!= 0 && known_base_value_p (tmp2
))
1731 /* We could not determine which of the two operands was the
1732 base register and which was the index. So we can determine
1733 nothing from the base alias check. */
1738 if (CONST_INT_P (XEXP (x
, 1)) && INTVAL (XEXP (x
, 1)) != 0)
1739 return find_base_term (XEXP (x
, 0));
1751 /* Return true if accesses to address X may alias accesses based
1752 on the stack pointer. */
1755 may_be_sp_based_p (rtx x
)
1757 rtx base
= find_base_term (x
);
1758 return !base
|| base
== static_reg_base_value
[STACK_POINTER_REGNUM
];
1761 /* Return 0 if the addresses X and Y are known to point to different
1762 objects, 1 if they might be pointers to the same object. */
1765 base_alias_check (rtx x
, rtx y
, enum machine_mode x_mode
,
1766 enum machine_mode y_mode
)
1768 rtx x_base
= find_base_term (x
);
1769 rtx y_base
= find_base_term (y
);
1771 /* If the address itself has no known base see if a known equivalent
1772 value has one. If either address still has no known base, nothing
1773 is known about aliasing. */
1778 if (! flag_expensive_optimizations
|| (x_c
= canon_rtx (x
)) == x
)
1781 x_base
= find_base_term (x_c
);
1789 if (! flag_expensive_optimizations
|| (y_c
= canon_rtx (y
)) == y
)
1792 y_base
= find_base_term (y_c
);
1797 /* If the base addresses are equal nothing is known about aliasing. */
1798 if (rtx_equal_p (x_base
, y_base
))
1801 /* The base addresses are different expressions. If they are not accessed
1802 via AND, there is no conflict. We can bring knowledge of object
1803 alignment into play here. For example, on alpha, "char a, b;" can
1804 alias one another, though "char a; long b;" cannot. AND addesses may
1805 implicitly alias surrounding objects; i.e. unaligned access in DImode
1806 via AND address can alias all surrounding object types except those
1807 with aligment 8 or higher. */
1808 if (GET_CODE (x
) == AND
&& GET_CODE (y
) == AND
)
1810 if (GET_CODE (x
) == AND
1811 && (!CONST_INT_P (XEXP (x
, 1))
1812 || (int) GET_MODE_UNIT_SIZE (y_mode
) < -INTVAL (XEXP (x
, 1))))
1814 if (GET_CODE (y
) == AND
1815 && (!CONST_INT_P (XEXP (y
, 1))
1816 || (int) GET_MODE_UNIT_SIZE (x_mode
) < -INTVAL (XEXP (y
, 1))))
1819 /* Differing symbols not accessed via AND never alias. */
1820 if (GET_CODE (x_base
) != ADDRESS
&& GET_CODE (y_base
) != ADDRESS
)
1823 if (unique_base_value_p (x_base
) || unique_base_value_p (y_base
))
1829 /* Callback for for_each_rtx, that returns 1 upon encountering a VALUE
1830 whose UID is greater than the int uid that D points to. */
1833 refs_newer_value_cb (rtx
*x
, void *d
)
1835 if (GET_CODE (*x
) == VALUE
&& CSELIB_VAL_PTR (*x
)->uid
> *(int *)d
)
1841 /* Return TRUE if EXPR refers to a VALUE whose uid is greater than
1845 refs_newer_value_p (rtx expr
, rtx v
)
1847 int minuid
= CSELIB_VAL_PTR (v
)->uid
;
1849 return for_each_rtx (&expr
, refs_newer_value_cb
, &minuid
);
1852 /* Convert the address X into something we can use. This is done by returning
1853 it unchanged unless it is a value; in the latter case we call cselib to get
1854 a more useful rtx. */
1860 struct elt_loc_list
*l
;
1862 if (GET_CODE (x
) != VALUE
)
1864 v
= CSELIB_VAL_PTR (x
);
1867 bool have_equivs
= cselib_have_permanent_equivalences ();
1869 v
= canonical_cselib_val (v
);
1870 for (l
= v
->locs
; l
; l
= l
->next
)
1871 if (CONSTANT_P (l
->loc
))
1873 for (l
= v
->locs
; l
; l
= l
->next
)
1874 if (!REG_P (l
->loc
) && !MEM_P (l
->loc
)
1875 /* Avoid infinite recursion when potentially dealing with
1876 var-tracking artificial equivalences, by skipping the
1877 equivalences themselves, and not choosing expressions
1878 that refer to newer VALUEs. */
1880 || (GET_CODE (l
->loc
) != VALUE
1881 && !refs_newer_value_p (l
->loc
, x
))))
1885 for (l
= v
->locs
; l
; l
= l
->next
)
1887 || (GET_CODE (l
->loc
) != VALUE
1888 && !refs_newer_value_p (l
->loc
, x
)))
1890 /* Return the canonical value. */
1894 return v
->locs
->loc
;
1899 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
1900 where SIZE is the size in bytes of the memory reference. If ADDR
1901 is not modified by the memory reference then ADDR is returned. */
1904 addr_side_effect_eval (rtx addr
, int size
, int n_refs
)
1908 switch (GET_CODE (addr
))
1911 offset
= (n_refs
+ 1) * size
;
1914 offset
= -(n_refs
+ 1) * size
;
1917 offset
= n_refs
* size
;
1920 offset
= -n_refs
* size
;
1928 addr
= gen_rtx_PLUS (GET_MODE (addr
), XEXP (addr
, 0),
1931 addr
= XEXP (addr
, 0);
1932 addr
= canon_rtx (addr
);
1937 /* Return one if X and Y (memory addresses) reference the
1938 same location in memory or if the references overlap.
1939 Return zero if they do not overlap, else return
1940 minus one in which case they still might reference the same location.
1942 C is an offset accumulator. When
1943 C is nonzero, we are testing aliases between X and Y + C.
1944 XSIZE is the size in bytes of the X reference,
1945 similarly YSIZE is the size in bytes for Y.
1946 Expect that canon_rtx has been already called for X and Y.
1948 If XSIZE or YSIZE is zero, we do not know the amount of memory being
1949 referenced (the reference was BLKmode), so make the most pessimistic
1952 If XSIZE or YSIZE is negative, we may access memory outside the object
1953 being referenced as a side effect. This can happen when using AND to
1954 align memory references, as is done on the Alpha.
1956 Nice to notice that varying addresses cannot conflict with fp if no
1957 local variables had their addresses taken, but that's too hard now.
1959 ??? Contrary to the tree alias oracle this does not return
1960 one for X + non-constant and Y + non-constant when X and Y are equal.
1961 If that is fixed the TBAA hack for union type-punning can be removed. */
1964 memrefs_conflict_p (int xsize
, rtx x
, int ysize
, rtx y
, HOST_WIDE_INT c
)
1966 if (GET_CODE (x
) == VALUE
)
1970 struct elt_loc_list
*l
= NULL
;
1971 if (CSELIB_VAL_PTR (x
))
1972 for (l
= canonical_cselib_val (CSELIB_VAL_PTR (x
))->locs
;
1974 if (REG_P (l
->loc
) && rtx_equal_for_memref_p (l
->loc
, y
))
1981 /* Don't call get_addr if y is the same VALUE. */
1985 if (GET_CODE (y
) == VALUE
)
1989 struct elt_loc_list
*l
= NULL
;
1990 if (CSELIB_VAL_PTR (y
))
1991 for (l
= canonical_cselib_val (CSELIB_VAL_PTR (y
))->locs
;
1993 if (REG_P (l
->loc
) && rtx_equal_for_memref_p (l
->loc
, x
))
2000 /* Don't call get_addr if x is the same VALUE. */
2004 if (GET_CODE (x
) == HIGH
)
2006 else if (GET_CODE (x
) == LO_SUM
)
2009 x
= addr_side_effect_eval (x
, xsize
, 0);
2010 if (GET_CODE (y
) == HIGH
)
2012 else if (GET_CODE (y
) == LO_SUM
)
2015 y
= addr_side_effect_eval (y
, ysize
, 0);
2017 if (rtx_equal_for_memref_p (x
, y
))
2019 if (xsize
<= 0 || ysize
<= 0)
2021 if (c
>= 0 && xsize
> c
)
2023 if (c
< 0 && ysize
+c
> 0)
2028 /* This code used to check for conflicts involving stack references and
2029 globals but the base address alias code now handles these cases. */
2031 if (GET_CODE (x
) == PLUS
)
2033 /* The fact that X is canonicalized means that this
2034 PLUS rtx is canonicalized. */
2035 rtx x0
= XEXP (x
, 0);
2036 rtx x1
= XEXP (x
, 1);
2038 if (GET_CODE (y
) == PLUS
)
2040 /* The fact that Y is canonicalized means that this
2041 PLUS rtx is canonicalized. */
2042 rtx y0
= XEXP (y
, 0);
2043 rtx y1
= XEXP (y
, 1);
2045 if (rtx_equal_for_memref_p (x1
, y1
))
2046 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
2047 if (rtx_equal_for_memref_p (x0
, y0
))
2048 return memrefs_conflict_p (xsize
, x1
, ysize
, y1
, c
);
2049 if (CONST_INT_P (x1
))
2051 if (CONST_INT_P (y1
))
2052 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
,
2053 c
- INTVAL (x1
) + INTVAL (y1
));
2055 return memrefs_conflict_p (xsize
, x0
, ysize
, y
,
2058 else if (CONST_INT_P (y1
))
2059 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
2063 else if (CONST_INT_P (x1
))
2064 return memrefs_conflict_p (xsize
, x0
, ysize
, y
, c
- INTVAL (x1
));
2066 else if (GET_CODE (y
) == PLUS
)
2068 /* The fact that Y is canonicalized means that this
2069 PLUS rtx is canonicalized. */
2070 rtx y0
= XEXP (y
, 0);
2071 rtx y1
= XEXP (y
, 1);
2073 if (CONST_INT_P (y1
))
2074 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
2079 if (GET_CODE (x
) == GET_CODE (y
))
2080 switch (GET_CODE (x
))
2084 /* Handle cases where we expect the second operands to be the
2085 same, and check only whether the first operand would conflict
2088 rtx x1
= canon_rtx (XEXP (x
, 1));
2089 rtx y1
= canon_rtx (XEXP (y
, 1));
2090 if (! rtx_equal_for_memref_p (x1
, y1
))
2092 x0
= canon_rtx (XEXP (x
, 0));
2093 y0
= canon_rtx (XEXP (y
, 0));
2094 if (rtx_equal_for_memref_p (x0
, y0
))
2095 return (xsize
== 0 || ysize
== 0
2096 || (c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0));
2098 /* Can't properly adjust our sizes. */
2099 if (!CONST_INT_P (x1
))
2101 xsize
/= INTVAL (x1
);
2102 ysize
/= INTVAL (x1
);
2104 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
2111 /* Treat an access through an AND (e.g. a subword access on an Alpha)
2112 as an access with indeterminate size. Assume that references
2113 besides AND are aligned, so if the size of the other reference is
2114 at least as large as the alignment, assume no other overlap. */
2115 if (GET_CODE (x
) == AND
&& CONST_INT_P (XEXP (x
, 1)))
2117 if (GET_CODE (y
) == AND
|| ysize
< -INTVAL (XEXP (x
, 1)))
2119 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)), ysize
, y
, c
);
2121 if (GET_CODE (y
) == AND
&& CONST_INT_P (XEXP (y
, 1)))
2123 /* ??? If we are indexing far enough into the array/structure, we
2124 may yet be able to determine that we can not overlap. But we
2125 also need to that we are far enough from the end not to overlap
2126 a following reference, so we do nothing with that for now. */
2127 if (GET_CODE (x
) == AND
|| xsize
< -INTVAL (XEXP (y
, 1)))
2129 return memrefs_conflict_p (xsize
, x
, ysize
, canon_rtx (XEXP (y
, 0)), c
);
2134 if (CONST_INT_P (x
) && CONST_INT_P (y
))
2136 c
+= (INTVAL (y
) - INTVAL (x
));
2137 return (xsize
<= 0 || ysize
<= 0
2138 || (c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0));
2141 if (GET_CODE (x
) == CONST
)
2143 if (GET_CODE (y
) == CONST
)
2144 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2145 ysize
, canon_rtx (XEXP (y
, 0)), c
);
2147 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2150 if (GET_CODE (y
) == CONST
)
2151 return memrefs_conflict_p (xsize
, x
, ysize
,
2152 canon_rtx (XEXP (y
, 0)), c
);
2155 return (xsize
<= 0 || ysize
<= 0
2156 || (rtx_equal_for_memref_p (x
, y
)
2157 && ((c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0))));
2165 /* Functions to compute memory dependencies.
2167 Since we process the insns in execution order, we can build tables
2168 to keep track of what registers are fixed (and not aliased), what registers
2169 are varying in known ways, and what registers are varying in unknown
2172 If both memory references are volatile, then there must always be a
2173 dependence between the two references, since their order can not be
2174 changed. A volatile and non-volatile reference can be interchanged
2177 We also must allow AND addresses, because they may generate accesses
2178 outside the object being referenced. This is used to generate aligned
2179 addresses from unaligned addresses, for instance, the alpha
2180 storeqi_unaligned pattern. */
2182 /* Read dependence: X is read after read in MEM takes place. There can
2183 only be a dependence here if both reads are volatile. */
2186 read_dependence (const_rtx mem
, const_rtx x
)
2188 return MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
);
2191 /* Returns nonzero if something about the mode or address format MEM1
2192 indicates that it might well alias *anything*. */
2195 aliases_everything_p (const_rtx mem
)
2197 if (GET_CODE (XEXP (mem
, 0)) == AND
)
2198 /* If the address is an AND, it's very hard to know at what it is
2199 actually pointing. */
2205 /* Return true if we can determine that the fields referenced cannot
2206 overlap for any pair of objects. */
2209 nonoverlapping_component_refs_p (const_tree x
, const_tree y
)
2211 const_tree fieldx
, fieldy
, typex
, typey
, orig_y
;
2213 if (!flag_strict_aliasing
)
2218 /* The comparison has to be done at a common type, since we don't
2219 know how the inheritance hierarchy works. */
2223 fieldx
= TREE_OPERAND (x
, 1);
2224 typex
= TYPE_MAIN_VARIANT (DECL_FIELD_CONTEXT (fieldx
));
2229 fieldy
= TREE_OPERAND (y
, 1);
2230 typey
= TYPE_MAIN_VARIANT (DECL_FIELD_CONTEXT (fieldy
));
2235 y
= TREE_OPERAND (y
, 0);
2237 while (y
&& TREE_CODE (y
) == COMPONENT_REF
);
2239 x
= TREE_OPERAND (x
, 0);
2241 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
2242 /* Never found a common type. */
2246 /* If we're left with accessing different fields of a structure,
2248 if (TREE_CODE (typex
) == RECORD_TYPE
2249 && fieldx
!= fieldy
)
2252 /* The comparison on the current field failed. If we're accessing
2253 a very nested structure, look at the next outer level. */
2254 x
= TREE_OPERAND (x
, 0);
2255 y
= TREE_OPERAND (y
, 0);
2258 && TREE_CODE (x
) == COMPONENT_REF
2259 && TREE_CODE (y
) == COMPONENT_REF
);
2264 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
2267 decl_for_component_ref (tree x
)
2271 x
= TREE_OPERAND (x
, 0);
2273 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
2275 return x
&& DECL_P (x
) ? x
: NULL_TREE
;
2278 /* Walk up the COMPONENT_REF list in X and adjust *OFFSET to compensate
2279 for the offset of the field reference. *KNOWN_P says whether the
2283 adjust_offset_for_component_ref (tree x
, bool *known_p
,
2284 HOST_WIDE_INT
*offset
)
2290 tree xoffset
= component_ref_field_offset (x
);
2291 tree field
= TREE_OPERAND (x
, 1);
2293 if (! host_integerp (xoffset
, 1))
2298 *offset
+= (tree_low_cst (xoffset
, 1)
2299 + (tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1)
2302 x
= TREE_OPERAND (x
, 0);
2304 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
2307 /* Return nonzero if we can determine the exprs corresponding to memrefs
2308 X and Y and they do not overlap.
2309 If LOOP_VARIANT is set, skip offset-based disambiguation */
2312 nonoverlapping_memrefs_p (const_rtx x
, const_rtx y
, bool loop_invariant
)
2314 tree exprx
= MEM_EXPR (x
), expry
= MEM_EXPR (y
);
2317 bool moffsetx_known_p
, moffsety_known_p
;
2318 HOST_WIDE_INT moffsetx
= 0, moffsety
= 0;
2319 HOST_WIDE_INT offsetx
= 0, offsety
= 0, sizex
, sizey
, tem
;
2321 /* Unless both have exprs, we can't tell anything. */
2322 if (exprx
== 0 || expry
== 0)
2325 /* For spill-slot accesses make sure we have valid offsets. */
2326 if ((exprx
== get_spill_slot_decl (false)
2327 && ! MEM_OFFSET_KNOWN_P (x
))
2328 || (expry
== get_spill_slot_decl (false)
2329 && ! MEM_OFFSET_KNOWN_P (y
)))
2332 /* If both are field references, we may be able to determine something. */
2333 if (TREE_CODE (exprx
) == COMPONENT_REF
2334 && TREE_CODE (expry
) == COMPONENT_REF
2335 && nonoverlapping_component_refs_p (exprx
, expry
))
2339 /* If the field reference test failed, look at the DECLs involved. */
2340 moffsetx_known_p
= MEM_OFFSET_KNOWN_P (x
);
2341 if (moffsetx_known_p
)
2342 moffsetx
= MEM_OFFSET (x
);
2343 if (TREE_CODE (exprx
) == COMPONENT_REF
)
2345 tree t
= decl_for_component_ref (exprx
);
2348 adjust_offset_for_component_ref (exprx
, &moffsetx_known_p
, &moffsetx
);
2352 moffsety_known_p
= MEM_OFFSET_KNOWN_P (y
);
2353 if (moffsety_known_p
)
2354 moffsety
= MEM_OFFSET (y
);
2355 if (TREE_CODE (expry
) == COMPONENT_REF
)
2357 tree t
= decl_for_component_ref (expry
);
2360 adjust_offset_for_component_ref (expry
, &moffsety_known_p
, &moffsety
);
2364 if (! DECL_P (exprx
) || ! DECL_P (expry
))
2367 /* With invalid code we can end up storing into the constant pool.
2368 Bail out to avoid ICEing when creating RTL for this.
2369 See gfortran.dg/lto/20091028-2_0.f90. */
2370 if (TREE_CODE (exprx
) == CONST_DECL
2371 || TREE_CODE (expry
) == CONST_DECL
)
2374 rtlx
= DECL_RTL (exprx
);
2375 rtly
= DECL_RTL (expry
);
2377 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
2378 can't overlap unless they are the same because we never reuse that part
2379 of the stack frame used for locals for spilled pseudos. */
2380 if ((!MEM_P (rtlx
) || !MEM_P (rtly
))
2381 && ! rtx_equal_p (rtlx
, rtly
))
2384 /* If we have MEMs referring to different address spaces (which can
2385 potentially overlap), we cannot easily tell from the addresses
2386 whether the references overlap. */
2387 if (MEM_P (rtlx
) && MEM_P (rtly
)
2388 && MEM_ADDR_SPACE (rtlx
) != MEM_ADDR_SPACE (rtly
))
2391 /* Get the base and offsets of both decls. If either is a register, we
2392 know both are and are the same, so use that as the base. The only
2393 we can avoid overlap is if we can deduce that they are nonoverlapping
2394 pieces of that decl, which is very rare. */
2395 basex
= MEM_P (rtlx
) ? XEXP (rtlx
, 0) : rtlx
;
2396 if (GET_CODE (basex
) == PLUS
&& CONST_INT_P (XEXP (basex
, 1)))
2397 offsetx
= INTVAL (XEXP (basex
, 1)), basex
= XEXP (basex
, 0);
2399 basey
= MEM_P (rtly
) ? XEXP (rtly
, 0) : rtly
;
2400 if (GET_CODE (basey
) == PLUS
&& CONST_INT_P (XEXP (basey
, 1)))
2401 offsety
= INTVAL (XEXP (basey
, 1)), basey
= XEXP (basey
, 0);
2403 /* If the bases are different, we know they do not overlap if both
2404 are constants or if one is a constant and the other a pointer into the
2405 stack frame. Otherwise a different base means we can't tell if they
2407 if (! rtx_equal_p (basex
, basey
))
2408 return ((CONSTANT_P (basex
) && CONSTANT_P (basey
))
2409 || (CONSTANT_P (basex
) && REG_P (basey
)
2410 && REGNO_PTR_FRAME_P (REGNO (basey
)))
2411 || (CONSTANT_P (basey
) && REG_P (basex
)
2412 && REGNO_PTR_FRAME_P (REGNO (basex
))));
2414 /* Offset based disambiguation not appropriate for loop invariant */
2418 sizex
= (!MEM_P (rtlx
) ? (int) GET_MODE_SIZE (GET_MODE (rtlx
))
2419 : MEM_SIZE_KNOWN_P (rtlx
) ? MEM_SIZE (rtlx
)
2421 sizey
= (!MEM_P (rtly
) ? (int) GET_MODE_SIZE (GET_MODE (rtly
))
2422 : MEM_SIZE_KNOWN_P (rtly
) ? MEM_SIZE (rtly
)
2425 /* If we have an offset for either memref, it can update the values computed
2427 if (moffsetx_known_p
)
2428 offsetx
+= moffsetx
, sizex
-= moffsetx
;
2429 if (moffsety_known_p
)
2430 offsety
+= moffsety
, sizey
-= moffsety
;
2432 /* If a memref has both a size and an offset, we can use the smaller size.
2433 We can't do this if the offset isn't known because we must view this
2434 memref as being anywhere inside the DECL's MEM. */
2435 if (MEM_SIZE_KNOWN_P (x
) && moffsetx_known_p
)
2436 sizex
= MEM_SIZE (x
);
2437 if (MEM_SIZE_KNOWN_P (y
) && moffsety_known_p
)
2438 sizey
= MEM_SIZE (y
);
2440 /* Put the values of the memref with the lower offset in X's values. */
2441 if (offsetx
> offsety
)
2443 tem
= offsetx
, offsetx
= offsety
, offsety
= tem
;
2444 tem
= sizex
, sizex
= sizey
, sizey
= tem
;
2447 /* If we don't know the size of the lower-offset value, we can't tell
2448 if they conflict. Otherwise, we do the test. */
2449 return sizex
>= 0 && offsety
>= offsetx
+ sizex
;
2452 /* Helper for true_dependence and canon_true_dependence.
2453 Checks for true dependence: X is read after store in MEM takes place.
2455 If MEM_CANONICALIZED is FALSE, then X_ADDR and MEM_ADDR should be
2456 NULL_RTX, and the canonical addresses of MEM and X are both computed
2457 here. If MEM_CANONICALIZED, then MEM must be already canonicalized.
2459 If X_ADDR is non-NULL, it is used in preference of XEXP (x, 0).
2461 Returns 1 if there is a true dependence, 0 otherwise. */
2464 true_dependence_1 (const_rtx mem
, enum machine_mode mem_mode
, rtx mem_addr
,
2465 const_rtx x
, rtx x_addr
, bool mem_canonicalized
)
2470 gcc_checking_assert (mem_canonicalized
? (mem_addr
!= NULL_RTX
)
2471 : (mem_addr
== NULL_RTX
&& x_addr
== NULL_RTX
));
2473 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2476 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2477 This is used in epilogue deallocation functions, and in cselib. */
2478 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2480 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2482 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2483 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2486 /* Read-only memory is by definition never modified, and therefore can't
2487 conflict with anything. We don't expect to find read-only set on MEM,
2488 but stupid user tricks can produce them, so don't die. */
2489 if (MEM_READONLY_P (x
))
2492 /* If we have MEMs referring to different address spaces (which can
2493 potentially overlap), we cannot easily tell from the addresses
2494 whether the references overlap. */
2495 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
2500 mem_addr
= XEXP (mem
, 0);
2501 if (mem_mode
== VOIDmode
)
2502 mem_mode
= GET_MODE (mem
);
2507 x_addr
= XEXP (x
, 0);
2508 if (!((GET_CODE (x_addr
) == VALUE
2509 && GET_CODE (mem_addr
) != VALUE
2510 && reg_mentioned_p (x_addr
, mem_addr
))
2511 || (GET_CODE (x_addr
) != VALUE
2512 && GET_CODE (mem_addr
) == VALUE
2513 && reg_mentioned_p (mem_addr
, x_addr
))))
2515 x_addr
= get_addr (x_addr
);
2516 if (! mem_canonicalized
)
2517 mem_addr
= get_addr (mem_addr
);
2521 base
= find_base_term (x_addr
);
2522 if (base
&& (GET_CODE (base
) == LABEL_REF
2523 || (GET_CODE (base
) == SYMBOL_REF
2524 && CONSTANT_POOL_ADDRESS_P (base
))))
2527 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
), mem_mode
))
2530 x_addr
= canon_rtx (x_addr
);
2531 if (!mem_canonicalized
)
2532 mem_addr
= canon_rtx (mem_addr
);
2534 if ((ret
= memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
2535 SIZE_FOR_MODE (x
), x_addr
, 0)) != -1)
2538 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
2541 if (nonoverlapping_memrefs_p (mem
, x
, false))
2544 if (aliases_everything_p (x
))
2547 /* We cannot use aliases_everything_p to test MEM, since we must look
2548 at MEM_ADDR, rather than XEXP (mem, 0). */
2549 if (GET_CODE (mem_addr
) == AND
)
2552 /* ??? In true_dependence we also allow BLKmode to alias anything. Why
2553 don't we do this in anti_dependence and output_dependence? */
2554 if (mem_mode
== BLKmode
|| GET_MODE (x
) == BLKmode
)
2557 return rtx_refs_may_alias_p (x
, mem
, true);
2560 /* True dependence: X is read after store in MEM takes place. */
2563 true_dependence (const_rtx mem
, enum machine_mode mem_mode
, const_rtx x
)
2565 return true_dependence_1 (mem
, mem_mode
, NULL_RTX
,
2566 x
, NULL_RTX
, /*mem_canonicalized=*/false);
2569 /* Canonical true dependence: X is read after store in MEM takes place.
2570 Variant of true_dependence which assumes MEM has already been
2571 canonicalized (hence we no longer do that here).
2572 The mem_addr argument has been added, since true_dependence_1 computed
2573 this value prior to canonicalizing. */
2576 canon_true_dependence (const_rtx mem
, enum machine_mode mem_mode
, rtx mem_addr
,
2577 const_rtx x
, rtx x_addr
)
2579 return true_dependence_1 (mem
, mem_mode
, mem_addr
,
2580 x
, x_addr
, /*mem_canonicalized=*/true);
2583 /* Returns nonzero if a write to X might alias a previous read from
2584 (or, if WRITEP is nonzero, a write to) MEM. */
2587 write_dependence_p (const_rtx mem
, const_rtx x
, int writep
)
2589 rtx x_addr
, mem_addr
;
2593 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2596 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2597 This is used in epilogue deallocation functions. */
2598 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2600 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2602 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2603 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2606 /* A read from read-only memory can't conflict with read-write memory. */
2607 if (!writep
&& MEM_READONLY_P (mem
))
2610 /* If we have MEMs referring to different address spaces (which can
2611 potentially overlap), we cannot easily tell from the addresses
2612 whether the references overlap. */
2613 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
2616 x_addr
= XEXP (x
, 0);
2617 mem_addr
= XEXP (mem
, 0);
2618 if (!((GET_CODE (x_addr
) == VALUE
2619 && GET_CODE (mem_addr
) != VALUE
2620 && reg_mentioned_p (x_addr
, mem_addr
))
2621 || (GET_CODE (x_addr
) != VALUE
2622 && GET_CODE (mem_addr
) == VALUE
2623 && reg_mentioned_p (mem_addr
, x_addr
))))
2625 x_addr
= get_addr (x_addr
);
2626 mem_addr
= get_addr (mem_addr
);
2631 base
= find_base_term (mem_addr
);
2632 if (base
&& (GET_CODE (base
) == LABEL_REF
2633 || (GET_CODE (base
) == SYMBOL_REF
2634 && CONSTANT_POOL_ADDRESS_P (base
))))
2638 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
),
2642 x_addr
= canon_rtx (x_addr
);
2643 mem_addr
= canon_rtx (mem_addr
);
2645 if ((ret
= memrefs_conflict_p (SIZE_FOR_MODE (mem
), mem_addr
,
2646 SIZE_FOR_MODE (x
), x_addr
, 0)) != -1)
2649 if (nonoverlapping_memrefs_p (x
, mem
, false))
2652 return rtx_refs_may_alias_p (x
, mem
, false);
2655 /* Anti dependence: X is written after read in MEM takes place. */
2658 anti_dependence (const_rtx mem
, const_rtx x
)
2660 return write_dependence_p (mem
, x
, /*writep=*/0);
2663 /* Output dependence: X is written after store in MEM takes place. */
2666 output_dependence (const_rtx mem
, const_rtx x
)
2668 return write_dependence_p (mem
, x
, /*writep=*/1);
2673 /* Check whether X may be aliased with MEM. Don't do offset-based
2674 memory disambiguation & TBAA. */
2676 may_alias_p (const_rtx mem
, const_rtx x
)
2678 rtx x_addr
, mem_addr
;
2680 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2683 /* ??? In true_dependence we also allow BLKmode to alias anything. */
2684 if (GET_MODE (mem
) == BLKmode
|| GET_MODE (x
) == BLKmode
)
2687 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2688 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2691 /* Read-only memory is by definition never modified, and therefore can't
2692 conflict with anything. We don't expect to find read-only set on MEM,
2693 but stupid user tricks can produce them, so don't die. */
2694 if (MEM_READONLY_P (x
))
2697 /* If we have MEMs referring to different address spaces (which can
2698 potentially overlap), we cannot easily tell from the addresses
2699 whether the references overlap. */
2700 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
2703 x_addr
= XEXP (x
, 0);
2704 mem_addr
= XEXP (mem
, 0);
2705 if (!((GET_CODE (x_addr
) == VALUE
2706 && GET_CODE (mem_addr
) != VALUE
2707 && reg_mentioned_p (x_addr
, mem_addr
))
2708 || (GET_CODE (x_addr
) != VALUE
2709 && GET_CODE (mem_addr
) == VALUE
2710 && reg_mentioned_p (mem_addr
, x_addr
))))
2712 x_addr
= get_addr (x_addr
);
2713 mem_addr
= get_addr (mem_addr
);
2716 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
), GET_MODE (mem_addr
)))
2719 x_addr
= canon_rtx (x_addr
);
2720 mem_addr
= canon_rtx (mem_addr
);
2722 if (nonoverlapping_memrefs_p (mem
, x
, true))
2725 if (aliases_everything_p (x
))
2728 /* We cannot use aliases_everything_p to test MEM, since we must look
2729 at MEM_ADDR, rather than XEXP (mem, 0). */
2730 if (GET_CODE (mem_addr
) == AND
)
2733 /* TBAA not valid for loop_invarint */
2734 return rtx_refs_may_alias_p (x
, mem
, false);
2738 init_alias_target (void)
2742 if (!arg_base_value
)
2743 arg_base_value
= gen_rtx_ADDRESS (VOIDmode
, 0);
2745 memset (static_reg_base_value
, 0, sizeof static_reg_base_value
);
2747 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2748 /* Check whether this register can hold an incoming pointer
2749 argument. FUNCTION_ARG_REGNO_P tests outgoing register
2750 numbers, so translate if necessary due to register windows. */
2751 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i
))
2752 && HARD_REGNO_MODE_OK (i
, Pmode
))
2753 static_reg_base_value
[i
] = arg_base_value
;
2755 static_reg_base_value
[STACK_POINTER_REGNUM
]
2756 = unique_base_value (UNIQUE_BASE_VALUE_SP
);
2757 static_reg_base_value
[ARG_POINTER_REGNUM
]
2758 = unique_base_value (UNIQUE_BASE_VALUE_ARGP
);
2759 static_reg_base_value
[FRAME_POINTER_REGNUM
]
2760 = unique_base_value (UNIQUE_BASE_VALUE_FP
);
2761 #if !HARD_FRAME_POINTER_IS_FRAME_POINTER
2762 static_reg_base_value
[HARD_FRAME_POINTER_REGNUM
]
2763 = unique_base_value (UNIQUE_BASE_VALUE_HFP
);
2767 /* Set MEMORY_MODIFIED when X modifies DATA (that is assumed
2768 to be memory reference. */
2769 static bool memory_modified
;
2771 memory_modified_1 (rtx x
, const_rtx pat ATTRIBUTE_UNUSED
, void *data
)
2775 if (anti_dependence (x
, (const_rtx
)data
) || output_dependence (x
, (const_rtx
)data
))
2776 memory_modified
= true;
2781 /* Return true when INSN possibly modify memory contents of MEM
2782 (i.e. address can be modified). */
2784 memory_modified_in_insn_p (const_rtx mem
, const_rtx insn
)
2788 memory_modified
= false;
2789 note_stores (PATTERN (insn
), memory_modified_1
, CONST_CAST_RTX(mem
));
2790 return memory_modified
;
2793 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
2797 init_alias_analysis (void)
2799 unsigned int maxreg
= max_reg_num ();
2805 timevar_push (TV_ALIAS_ANALYSIS
);
2807 reg_known_value
= VEC_alloc (rtx
, gc
, maxreg
- FIRST_PSEUDO_REGISTER
);
2808 reg_known_equiv_p
= sbitmap_alloc (maxreg
- FIRST_PSEUDO_REGISTER
);
2810 /* If we have memory allocated from the previous run, use it. */
2811 if (old_reg_base_value
)
2812 reg_base_value
= old_reg_base_value
;
2815 VEC_truncate (rtx
, reg_base_value
, 0);
2817 VEC_safe_grow_cleared (rtx
, gc
, reg_base_value
, maxreg
);
2819 new_reg_base_value
= XNEWVEC (rtx
, maxreg
);
2820 reg_seen
= XNEWVEC (char, maxreg
);
2822 /* The basic idea is that each pass through this loop will use the
2823 "constant" information from the previous pass to propagate alias
2824 information through another level of assignments.
2826 This could get expensive if the assignment chains are long. Maybe
2827 we should throttle the number of iterations, possibly based on
2828 the optimization level or flag_expensive_optimizations.
2830 We could propagate more information in the first pass by making use
2831 of DF_REG_DEF_COUNT to determine immediately that the alias information
2832 for a pseudo is "constant".
2834 A program with an uninitialized variable can cause an infinite loop
2835 here. Instead of doing a full dataflow analysis to detect such problems
2836 we just cap the number of iterations for the loop.
2838 The state of the arrays for the set chain in question does not matter
2839 since the program has undefined behavior. */
2844 /* Assume nothing will change this iteration of the loop. */
2847 /* We want to assign the same IDs each iteration of this loop, so
2848 start counting from one each iteration of the loop. */
2851 /* We're at the start of the function each iteration through the
2852 loop, so we're copying arguments. */
2853 copying_arguments
= true;
2855 /* Wipe the potential alias information clean for this pass. */
2856 memset (new_reg_base_value
, 0, maxreg
* sizeof (rtx
));
2858 /* Wipe the reg_seen array clean. */
2859 memset (reg_seen
, 0, maxreg
);
2861 /* Mark all hard registers which may contain an address.
2862 The stack, frame and argument pointers may contain an address.
2863 An argument register which can hold a Pmode value may contain
2864 an address even if it is not in BASE_REGS.
2866 The address expression is VOIDmode for an argument and
2867 Pmode for other registers. */
2869 memcpy (new_reg_base_value
, static_reg_base_value
,
2870 FIRST_PSEUDO_REGISTER
* sizeof (rtx
));
2872 /* Walk the insns adding values to the new_reg_base_value array. */
2873 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
2879 #if defined (HAVE_prologue) || defined (HAVE_epilogue)
2880 /* The prologue/epilogue insns are not threaded onto the
2881 insn chain until after reload has completed. Thus,
2882 there is no sense wasting time checking if INSN is in
2883 the prologue/epilogue until after reload has completed. */
2884 if (reload_completed
2885 && prologue_epilogue_contains (insn
))
2889 /* If this insn has a noalias note, process it, Otherwise,
2890 scan for sets. A simple set will have no side effects
2891 which could change the base value of any other register. */
2893 if (GET_CODE (PATTERN (insn
)) == SET
2894 && REG_NOTES (insn
) != 0
2895 && find_reg_note (insn
, REG_NOALIAS
, NULL_RTX
))
2896 record_set (SET_DEST (PATTERN (insn
)), NULL_RTX
, NULL
);
2898 note_stores (PATTERN (insn
), record_set
, NULL
);
2900 set
= single_set (insn
);
2903 && REG_P (SET_DEST (set
))
2904 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
)
2906 unsigned int regno
= REGNO (SET_DEST (set
));
2907 rtx src
= SET_SRC (set
);
2910 note
= find_reg_equal_equiv_note (insn
);
2911 if (note
&& REG_NOTE_KIND (note
) == REG_EQUAL
2912 && DF_REG_DEF_COUNT (regno
) != 1)
2915 if (note
!= NULL_RTX
2916 && GET_CODE (XEXP (note
, 0)) != EXPR_LIST
2917 && ! rtx_varies_p (XEXP (note
, 0), 1)
2918 && ! reg_overlap_mentioned_p (SET_DEST (set
),
2921 set_reg_known_value (regno
, XEXP (note
, 0));
2922 set_reg_known_equiv_p (regno
,
2923 REG_NOTE_KIND (note
) == REG_EQUIV
);
2925 else if (DF_REG_DEF_COUNT (regno
) == 1
2926 && GET_CODE (src
) == PLUS
2927 && REG_P (XEXP (src
, 0))
2928 && (t
= get_reg_known_value (REGNO (XEXP (src
, 0))))
2929 && CONST_INT_P (XEXP (src
, 1)))
2931 t
= plus_constant (GET_MODE (src
), t
,
2932 INTVAL (XEXP (src
, 1)));
2933 set_reg_known_value (regno
, t
);
2934 set_reg_known_equiv_p (regno
, false);
2936 else if (DF_REG_DEF_COUNT (regno
) == 1
2937 && ! rtx_varies_p (src
, 1))
2939 set_reg_known_value (regno
, src
);
2940 set_reg_known_equiv_p (regno
, false);
2944 else if (NOTE_P (insn
)
2945 && NOTE_KIND (insn
) == NOTE_INSN_FUNCTION_BEG
)
2946 copying_arguments
= false;
2949 /* Now propagate values from new_reg_base_value to reg_base_value. */
2950 gcc_assert (maxreg
== (unsigned int) max_reg_num ());
2952 for (ui
= 0; ui
< maxreg
; ui
++)
2954 if (new_reg_base_value
[ui
]
2955 && new_reg_base_value
[ui
] != VEC_index (rtx
, reg_base_value
, ui
)
2956 && ! rtx_equal_p (new_reg_base_value
[ui
],
2957 VEC_index (rtx
, reg_base_value
, ui
)))
2959 VEC_replace (rtx
, reg_base_value
, ui
, new_reg_base_value
[ui
]);
2964 while (changed
&& ++pass
< MAX_ALIAS_LOOP_PASSES
);
2966 /* Fill in the remaining entries. */
2967 FOR_EACH_VEC_ELT (rtx
, reg_known_value
, i
, val
)
2969 int regno
= i
+ FIRST_PSEUDO_REGISTER
;
2971 set_reg_known_value (regno
, regno_reg_rtx
[regno
]);
2975 free (new_reg_base_value
);
2976 new_reg_base_value
= 0;
2979 timevar_pop (TV_ALIAS_ANALYSIS
);
2982 /* Equate REG_BASE_VALUE (reg1) to REG_BASE_VALUE (reg2).
2983 Special API for var-tracking pass purposes. */
2986 vt_equate_reg_base_value (const_rtx reg1
, const_rtx reg2
)
2988 VEC_replace (rtx
, reg_base_value
, REGNO (reg1
), REG_BASE_VALUE (reg2
));
2992 end_alias_analysis (void)
2994 old_reg_base_value
= reg_base_value
;
2995 VEC_free (rtx
, gc
, reg_known_value
);
2996 sbitmap_free (reg_known_equiv_p
);
2999 #include "gt-alias.h"