1 /* Alias analysis for GNU C
2 Copyright (C) 1997-2016 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
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
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/>. */
23 #include "coretypes.h"
31 #include "gimple-ssa.h"
34 #include "fold-const.h"
37 #include "langhooks.h"
42 /* The aliasing API provided here solves related but different problems:
44 Say there exists (in c)
58 Consider the four questions:
60 Can a store to x1 interfere with px2->y1?
61 Can a store to x1 interfere with px2->z2?
62 Can a store to x1 change the value pointed to by with py?
63 Can a store to x1 change the value pointed to by with pz?
65 The answer to these questions can be yes, yes, yes, and maybe.
67 The first two questions can be answered with a simple examination
68 of the type system. If structure X contains a field of type Y then
69 a store through a pointer to an X can overwrite any field that is
70 contained (recursively) in an X (unless we know that px1 != px2).
72 The last two questions can be solved in the same way as the first
73 two questions but this is too conservative. The observation is
74 that in some cases we can know which (if any) fields are addressed
75 and if those addresses are used in bad ways. This analysis may be
76 language specific. In C, arbitrary operations may be applied to
77 pointers. However, there is some indication that this may be too
78 conservative for some C++ types.
80 The pass ipa-type-escape does this analysis for the types whose
81 instances do not escape across the compilation boundary.
83 Historically in GCC, these two problems were combined and a single
84 data structure that was used to represent the solution to these
85 problems. We now have two similar but different data structures,
86 The data structure to solve the last two questions is similar to
87 the first, but does not contain the fields whose address are never
88 taken. For types that do escape the compilation unit, the data
89 structures will have identical information.
92 /* The alias sets assigned to MEMs assist the back-end in determining
93 which MEMs can alias which other MEMs. In general, two MEMs in
94 different alias sets cannot alias each other, with one important
95 exception. Consider something like:
97 struct S { int i; double d; };
99 a store to an `S' can alias something of either type `int' or type
100 `double'. (However, a store to an `int' cannot alias a `double'
101 and vice versa.) We indicate this via a tree structure that looks
109 (The arrows are directed and point downwards.)
110 In this situation we say the alias set for `struct S' is the
111 `superset' and that those for `int' and `double' are `subsets'.
113 To see whether two alias sets can point to the same memory, we must
114 see if either alias set is a subset of the other. We need not trace
115 past immediate descendants, however, since we propagate all
116 grandchildren up one level.
118 Alias set zero is implicitly a superset of all other alias sets.
119 However, this is no actual entry for alias set zero. It is an
120 error to attempt to explicitly construct a subset of zero. */
122 struct alias_set_hash
: int_hash
<int, INT_MIN
, INT_MIN
+ 1> {};
124 struct GTY(()) alias_set_entry
{
125 /* The alias set number, as stored in MEM_ALIAS_SET. */
126 alias_set_type alias_set
;
128 /* The children of the alias set. These are not just the immediate
129 children, but, in fact, all descendants. So, if we have:
131 struct T { struct S s; float f; }
133 continuing our example above, the children here will be all of
134 `int', `double', `float', and `struct S'. */
135 hash_map
<alias_set_hash
, int> *children
;
137 /* Nonzero if would have a child of zero: this effectively makes this
138 alias set the same as alias set zero. */
140 /* Nonzero if alias set corresponds to pointer type itself (i.e. not to
141 aggregate contaiing pointer.
142 This is used for a special case where we need an universal pointer type
143 compatible with all other pointer types. */
145 /* Nonzero if is_pointer or if one of childs have has_pointer set. */
149 static int rtx_equal_for_memref_p (const_rtx
, const_rtx
);
150 static int memrefs_conflict_p (int, rtx
, int, rtx
, HOST_WIDE_INT
);
151 static void record_set (rtx
, const_rtx
, void *);
152 static int base_alias_check (rtx
, rtx
, rtx
, rtx
, machine_mode
,
154 static rtx
find_base_value (rtx
);
155 static int mems_in_disjoint_alias_sets_p (const_rtx
, const_rtx
);
156 static alias_set_entry
*get_alias_set_entry (alias_set_type
);
157 static tree
decl_for_component_ref (tree
);
158 static int write_dependence_p (const_rtx
,
159 const_rtx
, machine_mode
, rtx
,
161 static int compare_base_symbol_refs (const_rtx
, const_rtx
);
163 static void memory_modified_1 (rtx
, const_rtx
, void *);
165 /* Query statistics for the different low-level disambiguators.
166 A high-level query may trigger multiple of them. */
169 unsigned long long num_alias_zero
;
170 unsigned long long num_same_alias_set
;
171 unsigned long long num_same_objects
;
172 unsigned long long num_volatile
;
173 unsigned long long num_dag
;
174 unsigned long long num_universal
;
175 unsigned long long num_disambiguated
;
179 /* Set up all info needed to perform alias analysis on memory references. */
181 /* Returns the size in bytes of the mode of X. */
182 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
184 /* Cap the number of passes we make over the insns propagating alias
185 information through set chains.
186 ??? 10 is a completely arbitrary choice. This should be based on the
187 maximum loop depth in the CFG, but we do not have this information
188 available (even if current_loops _is_ available). */
189 #define MAX_ALIAS_LOOP_PASSES 10
191 /* reg_base_value[N] gives an address to which register N is related.
192 If all sets after the first add or subtract to the current value
193 or otherwise modify it so it does not point to a different top level
194 object, reg_base_value[N] is equal to the address part of the source
197 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
198 expressions represent three types of base:
200 1. incoming arguments. There is just one ADDRESS to represent all
201 arguments, since we do not know at this level whether accesses
202 based on different arguments can alias. The ADDRESS has id 0.
204 2. stack_pointer_rtx, frame_pointer_rtx, hard_frame_pointer_rtx
205 (if distinct from frame_pointer_rtx) and arg_pointer_rtx.
206 Each of these rtxes has a separate ADDRESS associated with it,
207 each with a negative id.
209 GCC is (and is required to be) precise in which register it
210 chooses to access a particular region of stack. We can therefore
211 assume that accesses based on one of these rtxes do not alias
212 accesses based on another of these rtxes.
214 3. bases that are derived from malloc()ed memory (REG_NOALIAS).
215 Each such piece of memory has a separate ADDRESS associated
216 with it, each with an id greater than 0.
218 Accesses based on one ADDRESS do not alias accesses based on other
219 ADDRESSes. Accesses based on ADDRESSes in groups (2) and (3) do not
220 alias globals either; the ADDRESSes have Pmode to indicate this.
221 The ADDRESS in group (1) _may_ alias globals; it has VOIDmode to
224 static GTY(()) vec
<rtx
, va_gc
> *reg_base_value
;
225 static rtx
*new_reg_base_value
;
227 /* The single VOIDmode ADDRESS that represents all argument bases.
229 static GTY(()) rtx arg_base_value
;
231 /* Used to allocate unique ids to each REG_NOALIAS ADDRESS. */
232 static int unique_id
;
234 /* We preserve the copy of old array around to avoid amount of garbage
235 produced. About 8% of garbage produced were attributed to this
237 static GTY((deletable
)) vec
<rtx
, va_gc
> *old_reg_base_value
;
239 /* Values of XINT (address, 0) of Pmode ADDRESS rtxes for special
241 #define UNIQUE_BASE_VALUE_SP -1
242 #define UNIQUE_BASE_VALUE_ARGP -2
243 #define UNIQUE_BASE_VALUE_FP -3
244 #define UNIQUE_BASE_VALUE_HFP -4
246 #define static_reg_base_value \
247 (this_target_rtl->x_static_reg_base_value)
249 #define REG_BASE_VALUE(X) \
250 (REGNO (X) < vec_safe_length (reg_base_value) \
251 ? (*reg_base_value)[REGNO (X)] : 0)
253 /* Vector indexed by N giving the initial (unchanging) value known for
254 pseudo-register N. This vector is initialized in init_alias_analysis,
255 and does not change until end_alias_analysis is called. */
256 static GTY(()) vec
<rtx
, va_gc
> *reg_known_value
;
258 /* Vector recording for each reg_known_value whether it is due to a
259 REG_EQUIV note. Future passes (viz., reload) may replace the
260 pseudo with the equivalent expression and so we account for the
261 dependences that would be introduced if that happens.
263 The REG_EQUIV notes created in assign_parms may mention the arg
264 pointer, and there are explicit insns in the RTL that modify the
265 arg pointer. Thus we must ensure that such insns don't get
266 scheduled across each other because that would invalidate the
267 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
268 wrong, but solving the problem in the scheduler will likely give
269 better code, so we do it here. */
270 static sbitmap reg_known_equiv_p
;
272 /* True when scanning insns from the start of the rtl to the
273 NOTE_INSN_FUNCTION_BEG note. */
274 static bool copying_arguments
;
277 /* The splay-tree used to store the various alias set entries. */
278 static GTY (()) vec
<alias_set_entry
*, va_gc
> *alias_sets
;
280 /* Build a decomposed reference object for querying the alias-oracle
281 from the MEM rtx and store it in *REF.
282 Returns false if MEM is not suitable for the alias-oracle. */
285 ao_ref_from_mem (ao_ref
*ref
, const_rtx mem
)
287 tree expr
= MEM_EXPR (mem
);
293 ao_ref_init (ref
, expr
);
295 /* Get the base of the reference and see if we have to reject or
297 base
= ao_ref_base (ref
);
298 if (base
== NULL_TREE
)
301 /* The tree oracle doesn't like bases that are neither decls
302 nor indirect references of SSA names. */
304 || (TREE_CODE (base
) == MEM_REF
305 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
306 || (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 a MEM_REF of the pointer representative we
312 created during stack slot partitioning. */
313 if (TREE_CODE (base
) == VAR_DECL
314 && ! is_global_var (base
)
315 && cfun
->gimple_df
->decls_to_pointers
!= NULL
)
317 tree
*namep
= cfun
->gimple_df
->decls_to_pointers
->get (base
);
319 ref
->base
= build_simple_mem_ref (*namep
);
322 ref
->ref_alias_set
= MEM_ALIAS_SET (mem
);
324 /* If MEM_OFFSET or MEM_SIZE are unknown what we got from MEM_EXPR
325 is conservative, so trust it. */
326 if (!MEM_OFFSET_KNOWN_P (mem
)
327 || !MEM_SIZE_KNOWN_P (mem
))
330 /* If MEM_OFFSET/MEM_SIZE get us outside of ref->offset/ref->max_size
332 if (MEM_OFFSET (mem
) < 0
333 || (ref
->max_size
!= -1
334 && ((MEM_OFFSET (mem
) + MEM_SIZE (mem
)) * BITS_PER_UNIT
336 ref
->ref
= NULL_TREE
;
338 /* Refine size and offset we got from analyzing MEM_EXPR by using
339 MEM_SIZE and MEM_OFFSET. */
341 ref
->offset
+= MEM_OFFSET (mem
) * BITS_PER_UNIT
;
342 ref
->size
= MEM_SIZE (mem
) * BITS_PER_UNIT
;
344 /* The MEM may extend into adjacent fields, so adjust max_size if
346 if (ref
->max_size
!= -1
347 && ref
->size
> ref
->max_size
)
348 ref
->max_size
= ref
->size
;
350 /* If MEM_OFFSET and MEM_SIZE get us outside of the base object of
351 the MEM_EXPR punt. This happens for STRICT_ALIGNMENT targets a lot. */
352 if (MEM_EXPR (mem
) != get_spill_slot_decl (false)
354 || (DECL_P (ref
->base
)
355 && (DECL_SIZE (ref
->base
) == NULL_TREE
356 || TREE_CODE (DECL_SIZE (ref
->base
)) != INTEGER_CST
357 || wi::ltu_p (wi::to_offset (DECL_SIZE (ref
->base
)),
358 ref
->offset
+ ref
->size
)))))
364 /* Query the alias-oracle on whether the two memory rtx X and MEM may
365 alias. If TBAA_P is set also apply TBAA. Returns true if the
366 two rtxen may alias, false otherwise. */
369 rtx_refs_may_alias_p (const_rtx x
, const_rtx mem
, bool tbaa_p
)
373 if (!ao_ref_from_mem (&ref1
, x
)
374 || !ao_ref_from_mem (&ref2
, mem
))
377 return refs_may_alias_p_1 (&ref1
, &ref2
,
379 && MEM_ALIAS_SET (x
) != 0
380 && MEM_ALIAS_SET (mem
) != 0);
383 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
384 such an entry, or NULL otherwise. */
386 static inline alias_set_entry
*
387 get_alias_set_entry (alias_set_type alias_set
)
389 return (*alias_sets
)[alias_set
];
392 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
393 the two MEMs cannot alias each other. */
396 mems_in_disjoint_alias_sets_p (const_rtx mem1
, const_rtx mem2
)
398 return (flag_strict_aliasing
399 && ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1
),
400 MEM_ALIAS_SET (mem2
)));
403 /* Return true if the first alias set is a subset of the second. */
406 alias_set_subset_of (alias_set_type set1
, alias_set_type set2
)
408 alias_set_entry
*ase2
;
410 /* Disable TBAA oracle with !flag_strict_aliasing. */
411 if (!flag_strict_aliasing
)
414 /* Everything is a subset of the "aliases everything" set. */
418 /* Check if set1 is a subset of set2. */
419 ase2
= get_alias_set_entry (set2
);
421 && (ase2
->has_zero_child
422 || (ase2
->children
&& ase2
->children
->get (set1
))))
425 /* As a special case we consider alias set of "void *" to be both subset
426 and superset of every alias set of a pointer. This extra symmetry does
427 not matter for alias_sets_conflict_p but it makes aliasing_component_refs_p
428 to return true on the following testcase:
431 char **ptr2=(char **)&ptr;
434 Additionally if a set contains universal pointer, we consider every pointer
435 to be a subset of it, but we do not represent this explicitely - doing so
436 would require us to update transitive closure each time we introduce new
437 pointer type. This makes aliasing_component_refs_p to return true
438 on the following testcase:
440 struct a {void *ptr;}
441 char **ptr = (char **)&a.ptr;
444 This makes void * truly universal pointer type. See pointer handling in
445 get_alias_set for more details. */
446 if (ase2
&& ase2
->has_pointer
)
448 alias_set_entry
*ase1
= get_alias_set_entry (set1
);
450 if (ase1
&& ase1
->is_pointer
)
452 alias_set_type voidptr_set
= TYPE_ALIAS_SET (ptr_type_node
);
453 /* If one is ptr_type_node and other is pointer, then we consider
454 them subset of each other. */
455 if (set1
== voidptr_set
|| set2
== voidptr_set
)
457 /* If SET2 contains universal pointer's alias set, then we consdier
458 every (non-universal) pointer. */
459 if (ase2
->children
&& set1
!= voidptr_set
460 && ase2
->children
->get (voidptr_set
))
467 /* Return 1 if the two specified alias sets may conflict. */
470 alias_sets_conflict_p (alias_set_type set1
, alias_set_type set2
)
472 alias_set_entry
*ase1
;
473 alias_set_entry
*ase2
;
476 if (alias_sets_must_conflict_p (set1
, set2
))
479 /* See if the first alias set is a subset of the second. */
480 ase1
= get_alias_set_entry (set1
);
482 && ase1
->children
&& ase1
->children
->get (set2
))
484 ++alias_stats
.num_dag
;
488 /* Now do the same, but with the alias sets reversed. */
489 ase2
= get_alias_set_entry (set2
);
491 && ase2
->children
&& ase2
->children
->get (set1
))
493 ++alias_stats
.num_dag
;
497 /* We want void * to be compatible with any other pointer without
498 really dropping it to alias set 0. Doing so would make it
499 compatible with all non-pointer types too.
501 This is not strictly necessary by the C/C++ language
502 standards, but avoids common type punning mistakes. In
503 addition to that, we need the existence of such universal
504 pointer to implement Fortran's C_PTR type (which is defined as
505 type compatible with all C pointers). */
506 if (ase1
&& ase2
&& ase1
->has_pointer
&& ase2
->has_pointer
)
508 alias_set_type voidptr_set
= TYPE_ALIAS_SET (ptr_type_node
);
510 /* If one of the sets corresponds to universal pointer,
511 we consider it to conflict with anything that is
512 or contains pointer. */
513 if (set1
== voidptr_set
|| set2
== voidptr_set
)
515 ++alias_stats
.num_universal
;
518 /* If one of sets is (non-universal) pointer and the other
519 contains universal pointer, we also get conflict. */
520 if (ase1
->is_pointer
&& set2
!= voidptr_set
521 && ase2
->children
&& ase2
->children
->get (voidptr_set
))
523 ++alias_stats
.num_universal
;
526 if (ase2
->is_pointer
&& set1
!= voidptr_set
527 && ase1
->children
&& ase1
->children
->get (voidptr_set
))
529 ++alias_stats
.num_universal
;
534 ++alias_stats
.num_disambiguated
;
536 /* The two alias sets are distinct and neither one is the
537 child of the other. Therefore, they cannot conflict. */
541 /* Return 1 if the two specified alias sets will always conflict. */
544 alias_sets_must_conflict_p (alias_set_type set1
, alias_set_type set2
)
546 /* Disable TBAA oracle with !flag_strict_aliasing. */
547 if (!flag_strict_aliasing
)
549 if (set1
== 0 || set2
== 0)
551 ++alias_stats
.num_alias_zero
;
556 ++alias_stats
.num_same_alias_set
;
563 /* Return 1 if any MEM object of type T1 will always conflict (using the
564 dependency routines in this file) with any MEM object of type T2.
565 This is used when allocating temporary storage. If T1 and/or T2 are
566 NULL_TREE, it means we know nothing about the storage. */
569 objects_must_conflict_p (tree t1
, tree t2
)
571 alias_set_type set1
, set2
;
573 /* If neither has a type specified, we don't know if they'll conflict
574 because we may be using them to store objects of various types, for
575 example the argument and local variables areas of inlined functions. */
576 if (t1
== 0 && t2
== 0)
579 /* If they are the same type, they must conflict. */
582 ++alias_stats
.num_same_objects
;
585 /* Likewise if both are volatile. */
586 if (t1
!= 0 && TYPE_VOLATILE (t1
) && t2
!= 0 && TYPE_VOLATILE (t2
))
588 ++alias_stats
.num_volatile
;
592 set1
= t1
? get_alias_set (t1
) : 0;
593 set2
= t2
? get_alias_set (t2
) : 0;
595 /* We can't use alias_sets_conflict_p because we must make sure
596 that every subtype of t1 will conflict with every subtype of
597 t2 for which a pair of subobjects of these respective subtypes
598 overlaps on the stack. */
599 return alias_sets_must_conflict_p (set1
, set2
);
602 /* Return the outermost parent of component present in the chain of
603 component references handled by get_inner_reference in T with the
605 - the component is non-addressable, or
606 - the parent has alias set zero,
607 or NULL_TREE if no such parent exists. In the former cases, the alias
608 set of this parent is the alias set that must be used for T itself. */
611 component_uses_parent_alias_set_from (const_tree t
)
613 const_tree found
= NULL_TREE
;
615 while (handled_component_p (t
))
617 switch (TREE_CODE (t
))
620 if (DECL_NONADDRESSABLE_P (TREE_OPERAND (t
, 1)))
625 case ARRAY_RANGE_REF
:
626 if (TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t
, 0))))
635 case VIEW_CONVERT_EXPR
:
636 /* Bitfields and casts are never addressable. */
644 if (get_alias_set (TREE_TYPE (TREE_OPERAND (t
, 0))) == 0)
647 t
= TREE_OPERAND (t
, 0);
651 return TREE_OPERAND (found
, 0);
657 /* Return whether the pointer-type T effective for aliasing may
658 access everything and thus the reference has to be assigned
662 ref_all_alias_ptr_type_p (const_tree t
)
664 return (TREE_CODE (TREE_TYPE (t
)) == VOID_TYPE
665 || TYPE_REF_CAN_ALIAS_ALL (t
));
668 /* Return the alias set for the memory pointed to by T, which may be
669 either a type or an expression. Return -1 if there is nothing
670 special about dereferencing T. */
672 static alias_set_type
673 get_deref_alias_set_1 (tree t
)
675 /* All we care about is the type. */
679 /* If we have an INDIRECT_REF via a void pointer, we don't
680 know anything about what that might alias. Likewise if the
681 pointer is marked that way. */
682 if (ref_all_alias_ptr_type_p (t
))
688 /* Return the alias set for the memory pointed to by T, which may be
689 either a type or an expression. */
692 get_deref_alias_set (tree t
)
694 /* If we're not doing any alias analysis, just assume everything
695 aliases everything else. */
696 if (!flag_strict_aliasing
)
699 alias_set_type set
= get_deref_alias_set_1 (t
);
701 /* Fall back to the alias-set of the pointed-to type. */
706 set
= get_alias_set (TREE_TYPE (t
));
712 /* Return the pointer-type relevant for TBAA purposes from the
713 memory reference tree *T or NULL_TREE in which case *T is
714 adjusted to point to the outermost component reference that
715 can be used for assigning an alias set. */
718 reference_alias_ptr_type_1 (tree
*t
)
722 /* Get the base object of the reference. */
724 while (handled_component_p (inner
))
726 /* If there is a VIEW_CONVERT_EXPR in the chain we cannot use
727 the type of any component references that wrap it to
728 determine the alias-set. */
729 if (TREE_CODE (inner
) == VIEW_CONVERT_EXPR
)
730 *t
= TREE_OPERAND (inner
, 0);
731 inner
= TREE_OPERAND (inner
, 0);
734 /* Handle pointer dereferences here, they can override the
736 if (INDIRECT_REF_P (inner
)
737 && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner
, 0))))
738 return TREE_TYPE (TREE_OPERAND (inner
, 0));
739 else if (TREE_CODE (inner
) == TARGET_MEM_REF
)
740 return TREE_TYPE (TMR_OFFSET (inner
));
741 else if (TREE_CODE (inner
) == MEM_REF
742 && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner
, 1))))
743 return TREE_TYPE (TREE_OPERAND (inner
, 1));
745 /* If the innermost reference is a MEM_REF that has a
746 conversion embedded treat it like a VIEW_CONVERT_EXPR above,
747 using the memory access type for determining the alias-set. */
748 if (TREE_CODE (inner
) == MEM_REF
749 && (TYPE_MAIN_VARIANT (TREE_TYPE (inner
))
751 (TREE_TYPE (TREE_TYPE (TREE_OPERAND (inner
, 1))))))
752 return TREE_TYPE (TREE_OPERAND (inner
, 1));
754 /* Otherwise, pick up the outermost object that we could have
756 tree tem
= component_uses_parent_alias_set_from (*t
);
763 /* Return the pointer-type relevant for TBAA purposes from the
764 gimple memory reference tree T. This is the type to be used for
765 the offset operand of MEM_REF or TARGET_MEM_REF replacements of T
766 and guarantees that get_alias_set will return the same alias
767 set for T and the replacement. */
770 reference_alias_ptr_type (tree t
)
772 /* If the frontend assigns this alias-set zero, preserve that. */
773 if (lang_hooks
.get_alias_set (t
) == 0)
774 return ptr_type_node
;
776 tree ptype
= reference_alias_ptr_type_1 (&t
);
777 /* If there is a given pointer type for aliasing purposes, return it. */
778 if (ptype
!= NULL_TREE
)
781 /* Otherwise build one from the outermost component reference we
783 if (TREE_CODE (t
) == MEM_REF
784 || TREE_CODE (t
) == TARGET_MEM_REF
)
785 return TREE_TYPE (TREE_OPERAND (t
, 1));
787 return build_pointer_type (TYPE_MAIN_VARIANT (TREE_TYPE (t
)));
790 /* Return whether the pointer-types T1 and T2 used to determine
791 two alias sets of two references will yield the same answer
792 from get_deref_alias_set. */
795 alias_ptr_types_compatible_p (tree t1
, tree t2
)
797 if (TYPE_MAIN_VARIANT (t1
) == TYPE_MAIN_VARIANT (t2
))
800 if (ref_all_alias_ptr_type_p (t1
)
801 || ref_all_alias_ptr_type_p (t2
))
804 return (TYPE_MAIN_VARIANT (TREE_TYPE (t1
))
805 == TYPE_MAIN_VARIANT (TREE_TYPE (t2
)));
808 /* Create emptry alias set entry. */
811 init_alias_set_entry (alias_set_type set
)
813 alias_set_entry
*ase
= ggc_alloc
<alias_set_entry
> ();
814 ase
->alias_set
= set
;
815 ase
->children
= NULL
;
816 ase
->has_zero_child
= false;
817 ase
->is_pointer
= false;
818 ase
->has_pointer
= false;
819 gcc_checking_assert (!get_alias_set_entry (set
));
820 (*alias_sets
)[set
] = ase
;
824 /* Return the alias set for T, which may be either a type or an
825 expression. Call language-specific routine for help, if needed. */
828 get_alias_set (tree t
)
832 /* We can not give up with -fno-strict-aliasing because we need to build
833 proper type representation for possible functions which are build with
834 -fstrict-aliasing. */
836 /* return 0 if this or its type is an error. */
837 if (t
== error_mark_node
839 && (TREE_TYPE (t
) == 0 || TREE_TYPE (t
) == error_mark_node
)))
842 /* We can be passed either an expression or a type. This and the
843 language-specific routine may make mutually-recursive calls to each other
844 to figure out what to do. At each juncture, we see if this is a tree
845 that the language may need to handle specially. First handle things that
849 /* Give the language a chance to do something with this tree
850 before we look at it. */
852 set
= lang_hooks
.get_alias_set (t
);
856 /* Get the alias pointer-type to use or the outermost object
857 that we could have a pointer to. */
858 tree ptype
= reference_alias_ptr_type_1 (&t
);
860 return get_deref_alias_set (ptype
);
862 /* If we've already determined the alias set for a decl, just return
863 it. This is necessary for C++ anonymous unions, whose component
864 variables don't look like union members (boo!). */
865 if (TREE_CODE (t
) == VAR_DECL
866 && DECL_RTL_SET_P (t
) && MEM_P (DECL_RTL (t
)))
867 return MEM_ALIAS_SET (DECL_RTL (t
));
869 /* Now all we care about is the type. */
873 /* Variant qualifiers don't affect the alias set, so get the main
875 t
= TYPE_MAIN_VARIANT (t
);
877 /* Always use the canonical type as well. If this is a type that
878 requires structural comparisons to identify compatible types
879 use alias set zero. */
880 if (TYPE_STRUCTURAL_EQUALITY_P (t
))
882 /* Allow the language to specify another alias set for this
884 set
= lang_hooks
.get_alias_set (t
);
887 /* Handle structure type equality for pointer types, arrays and vectors.
888 This is easy to do, because the code bellow ignore canonical types on
889 these anyway. This is important for LTO, where TYPE_CANONICAL for
890 pointers can not be meaningfuly computed by the frotnend. */
891 if (canonical_type_used_p (t
))
893 /* In LTO we set canonical types for all types where it makes
894 sense to do so. Double check we did not miss some type. */
895 gcc_checking_assert (!in_lto_p
|| !type_with_alias_set_p (t
));
901 t
= TYPE_CANONICAL (t
);
902 gcc_checking_assert (!TYPE_STRUCTURAL_EQUALITY_P (t
));
905 /* If this is a type with a known alias set, return it. */
906 gcc_checking_assert (t
== TYPE_MAIN_VARIANT (t
));
907 if (TYPE_ALIAS_SET_KNOWN_P (t
))
908 return TYPE_ALIAS_SET (t
);
910 /* We don't want to set TYPE_ALIAS_SET for incomplete types. */
911 if (!COMPLETE_TYPE_P (t
))
913 /* For arrays with unknown size the conservative answer is the
914 alias set of the element type. */
915 if (TREE_CODE (t
) == ARRAY_TYPE
)
916 return get_alias_set (TREE_TYPE (t
));
918 /* But return zero as a conservative answer for incomplete types. */
922 /* See if the language has special handling for this type. */
923 set
= lang_hooks
.get_alias_set (t
);
927 /* There are no objects of FUNCTION_TYPE, so there's no point in
928 using up an alias set for them. (There are, of course, pointers
929 and references to functions, but that's different.) */
930 else if (TREE_CODE (t
) == FUNCTION_TYPE
|| TREE_CODE (t
) == METHOD_TYPE
)
933 /* Unless the language specifies otherwise, let vector types alias
934 their components. This avoids some nasty type punning issues in
935 normal usage. And indeed lets vectors be treated more like an
937 else if (TREE_CODE (t
) == VECTOR_TYPE
)
938 set
= get_alias_set (TREE_TYPE (t
));
940 /* Unless the language specifies otherwise, treat array types the
941 same as their components. This avoids the asymmetry we get
942 through recording the components. Consider accessing a
943 character(kind=1) through a reference to a character(kind=1)[1:1].
944 Or consider if we want to assign integer(kind=4)[0:D.1387] and
945 integer(kind=4)[4] the same alias set or not.
946 Just be pragmatic here and make sure the array and its element
947 type get the same alias set assigned. */
948 else if (TREE_CODE (t
) == ARRAY_TYPE
949 && (!TYPE_NONALIASED_COMPONENT (t
)
950 || TYPE_STRUCTURAL_EQUALITY_P (t
)))
951 set
= get_alias_set (TREE_TYPE (t
));
953 /* From the former common C and C++ langhook implementation:
955 Unfortunately, there is no canonical form of a pointer type.
956 In particular, if we have `typedef int I', then `int *', and
957 `I *' are different types. So, we have to pick a canonical
958 representative. We do this below.
960 Technically, this approach is actually more conservative that
961 it needs to be. In particular, `const int *' and `int *'
962 should be in different alias sets, according to the C and C++
963 standard, since their types are not the same, and so,
964 technically, an `int **' and `const int **' cannot point at
967 But, the standard is wrong. In particular, this code is
972 const int* const* cipp = ipp;
973 And, it doesn't make sense for that to be legal unless you
974 can dereference IPP and CIPP. So, we ignore cv-qualifiers on
975 the pointed-to types. This issue has been reported to the
978 For this reason go to canonical type of the unqalified pointer type.
979 Until GCC 6 this code set all pointers sets to have alias set of
980 ptr_type_node but that is a bad idea, because it prevents disabiguations
981 in between pointers. For Firefox this accounts about 20% of all
982 disambiguations in the program. */
983 else if (POINTER_TYPE_P (t
) && t
!= ptr_type_node
)
986 auto_vec
<bool, 8> reference
;
988 /* Unnest all pointers and references.
989 We also want to make pointer to array/vector equivalent to pointer to
990 its element (see the reasoning above). Skip all those types, too. */
991 for (p
= t
; POINTER_TYPE_P (p
)
992 || (TREE_CODE (p
) == ARRAY_TYPE
993 && (!TYPE_NONALIASED_COMPONENT (p
)
994 || !COMPLETE_TYPE_P (p
)
995 || TYPE_STRUCTURAL_EQUALITY_P (p
)))
996 || TREE_CODE (p
) == VECTOR_TYPE
;
999 /* Ada supports recusive pointers. Instead of doing recrusion check
1000 just give up once the preallocated space of 8 elements is up.
1001 In this case just punt to void * alias set. */
1002 if (reference
.length () == 8)
1007 if (TREE_CODE (p
) == REFERENCE_TYPE
)
1008 /* In LTO we want languages that use references to be compatible
1009 with languages that use pointers. */
1010 reference
.safe_push (true && !in_lto_p
);
1011 if (TREE_CODE (p
) == POINTER_TYPE
)
1012 reference
.safe_push (false);
1014 p
= TYPE_MAIN_VARIANT (p
);
1016 /* Make void * compatible with char * and also void **.
1017 Programs are commonly violating TBAA by this.
1019 We also make void * to conflict with every pointer
1020 (see record_component_aliases) and thus it is safe it to use it for
1021 pointers to types with TYPE_STRUCTURAL_EQUALITY_P. */
1022 if (TREE_CODE (p
) == VOID_TYPE
|| TYPE_STRUCTURAL_EQUALITY_P (p
))
1023 set
= get_alias_set (ptr_type_node
);
1026 /* Rebuild pointer type starting from canonical types using
1027 unqualified pointers and references only. This way all such
1028 pointers will have the same alias set and will conflict with
1031 Most of time we already have pointers or references of a given type.
1032 If not we build new one just to be sure that if someone later
1033 (probably only middle-end can, as we should assign all alias
1034 classes only after finishing translation unit) builds the pointer
1035 type, the canonical type will match. */
1036 p
= TYPE_CANONICAL (p
);
1037 while (!reference
.is_empty ())
1039 if (reference
.pop ())
1040 p
= build_reference_type (p
);
1042 p
= build_pointer_type (p
);
1043 gcc_checking_assert (p
== TYPE_MAIN_VARIANT (p
));
1044 /* build_pointer_type should always return the canonical type.
1045 For LTO TYPE_CANOINCAL may be NULL, because we do not compute
1046 them. Be sure that frontends do not glob canonical types of
1047 pointers in unexpected way and that p == TYPE_CANONICAL (p)
1048 in all other cases. */
1049 gcc_checking_assert (!TYPE_CANONICAL (p
)
1050 || p
== TYPE_CANONICAL (p
));
1053 /* Assign the alias set to both p and t.
1054 We can not call get_alias_set (p) here as that would trigger
1055 infinite recursion when p == t. In other cases it would just
1056 trigger unnecesary legwork of rebuilding the pointer again. */
1057 gcc_checking_assert (p
== TYPE_MAIN_VARIANT (p
));
1058 if (TYPE_ALIAS_SET_KNOWN_P (p
))
1059 set
= TYPE_ALIAS_SET (p
);
1062 set
= new_alias_set ();
1063 TYPE_ALIAS_SET (p
) = set
;
1067 /* Alias set of ptr_type_node is special and serve as universal pointer which
1068 is TBAA compatible with every other pointer type. Be sure we have the
1069 alias set built even for LTO which otherwise keeps all TYPE_CANONICAL
1070 of pointer types NULL. */
1071 else if (t
== ptr_type_node
)
1072 set
= new_alias_set ();
1074 /* Otherwise make a new alias set for this type. */
1077 /* Each canonical type gets its own alias set, so canonical types
1078 shouldn't form a tree. It doesn't really matter for types
1079 we handle specially above, so only check it where it possibly
1080 would result in a bogus alias set. */
1081 gcc_checking_assert (TYPE_CANONICAL (t
) == t
);
1083 set
= new_alias_set ();
1086 TYPE_ALIAS_SET (t
) = set
;
1088 /* If this is an aggregate type or a complex type, we must record any
1089 component aliasing information. */
1090 if (AGGREGATE_TYPE_P (t
) || TREE_CODE (t
) == COMPLEX_TYPE
)
1091 record_component_aliases (t
);
1093 /* We treat pointer types specially in alias_set_subset_of. */
1094 if (POINTER_TYPE_P (t
) && set
)
1096 alias_set_entry
*ase
= get_alias_set_entry (set
);
1098 ase
= init_alias_set_entry (set
);
1099 ase
->is_pointer
= true;
1100 ase
->has_pointer
= true;
1106 /* Return a brand-new alias set. */
1109 new_alias_set (void)
1111 if (alias_sets
== 0)
1112 vec_safe_push (alias_sets
, (alias_set_entry
*) NULL
);
1113 vec_safe_push (alias_sets
, (alias_set_entry
*) NULL
);
1114 return alias_sets
->length () - 1;
1117 /* Indicate that things in SUBSET can alias things in SUPERSET, but that
1118 not everything that aliases SUPERSET also aliases SUBSET. For example,
1119 in C, a store to an `int' can alias a load of a structure containing an
1120 `int', and vice versa. But it can't alias a load of a 'double' member
1121 of the same structure. Here, the structure would be the SUPERSET and
1122 `int' the SUBSET. This relationship is also described in the comment at
1123 the beginning of this file.
1125 This function should be called only once per SUPERSET/SUBSET pair.
1127 It is illegal for SUPERSET to be zero; everything is implicitly a
1128 subset of alias set zero. */
1131 record_alias_subset (alias_set_type superset
, alias_set_type subset
)
1133 alias_set_entry
*superset_entry
;
1134 alias_set_entry
*subset_entry
;
1136 /* It is possible in complex type situations for both sets to be the same,
1137 in which case we can ignore this operation. */
1138 if (superset
== subset
)
1141 gcc_assert (superset
);
1143 superset_entry
= get_alias_set_entry (superset
);
1144 if (superset_entry
== 0)
1146 /* Create an entry for the SUPERSET, so that we have a place to
1147 attach the SUBSET. */
1148 superset_entry
= init_alias_set_entry (superset
);
1152 superset_entry
->has_zero_child
= 1;
1155 subset_entry
= get_alias_set_entry (subset
);
1156 if (!superset_entry
->children
)
1157 superset_entry
->children
1158 = hash_map
<alias_set_hash
, int>::create_ggc (64);
1159 /* If there is an entry for the subset, enter all of its children
1160 (if they are not already present) as children of the SUPERSET. */
1163 if (subset_entry
->has_zero_child
)
1164 superset_entry
->has_zero_child
= true;
1165 if (subset_entry
->has_pointer
)
1166 superset_entry
->has_pointer
= true;
1168 if (subset_entry
->children
)
1170 hash_map
<alias_set_hash
, int>::iterator iter
1171 = subset_entry
->children
->begin ();
1172 for (; iter
!= subset_entry
->children
->end (); ++iter
)
1173 superset_entry
->children
->put ((*iter
).first
, (*iter
).second
);
1177 /* Enter the SUBSET itself as a child of the SUPERSET. */
1178 superset_entry
->children
->put (subset
, 0);
1182 /* Record that component types of TYPE, if any, are part of that type for
1183 aliasing purposes. For record types, we only record component types
1184 for fields that are not marked non-addressable. For array types, we
1185 only record the component type if it is not marked non-aliased. */
1188 record_component_aliases (tree type
)
1190 alias_set_type superset
= get_alias_set (type
);
1196 switch (TREE_CODE (type
))
1200 case QUAL_UNION_TYPE
:
1201 for (field
= TYPE_FIELDS (type
); field
!= 0; field
= DECL_CHAIN (field
))
1202 if (TREE_CODE (field
) == FIELD_DECL
&& !DECL_NONADDRESSABLE_P (field
))
1204 /* LTO type merging does not make any difference between
1205 component pointer types. We may have
1207 struct foo {int *a;};
1209 as TYPE_CANONICAL of
1211 struct bar {float *a;};
1213 Because accesses to int * and float * do not alias, we would get
1214 false negative when accessing the same memory location by
1215 float ** and bar *. We thus record the canonical type as:
1219 void * is special cased and works as a universal pointer type.
1220 Accesses to it conflicts with accesses to any other pointer
1222 tree t
= TREE_TYPE (field
);
1225 /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their
1226 element type and that type has to be normalized to void *,
1227 too, in the case it is a pointer. */
1228 while (!canonical_type_used_p (t
) && !POINTER_TYPE_P (t
))
1230 gcc_checking_assert (TYPE_STRUCTURAL_EQUALITY_P (t
));
1233 if (POINTER_TYPE_P (t
))
1235 else if (flag_checking
)
1236 gcc_checking_assert (get_alias_set (t
)
1237 == get_alias_set (TREE_TYPE (field
)));
1240 record_alias_subset (superset
, get_alias_set (t
));
1245 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
1248 /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their
1256 /* Allocate an alias set for use in storing and reading from the varargs
1259 static GTY(()) alias_set_type varargs_set
= -1;
1262 get_varargs_alias_set (void)
1265 /* We now lower VA_ARG_EXPR, and there's currently no way to attach the
1266 varargs alias set to an INDIRECT_REF (FIXME!), so we can't
1267 consistently use the varargs alias set for loads from the varargs
1268 area. So don't use it anywhere. */
1271 if (varargs_set
== -1)
1272 varargs_set
= new_alias_set ();
1278 /* Likewise, but used for the fixed portions of the frame, e.g., register
1281 static GTY(()) alias_set_type frame_set
= -1;
1284 get_frame_alias_set (void)
1286 if (frame_set
== -1)
1287 frame_set
= new_alias_set ();
1292 /* Create a new, unique base with id ID. */
1295 unique_base_value (HOST_WIDE_INT id
)
1297 return gen_rtx_ADDRESS (Pmode
, id
);
1300 /* Return true if accesses based on any other base value cannot alias
1301 those based on X. */
1304 unique_base_value_p (rtx x
)
1306 return GET_CODE (x
) == ADDRESS
&& GET_MODE (x
) == Pmode
;
1309 /* Return true if X is known to be a base value. */
1312 known_base_value_p (rtx x
)
1314 switch (GET_CODE (x
))
1321 /* Arguments may or may not be bases; we don't know for sure. */
1322 return GET_MODE (x
) != VOIDmode
;
1329 /* Inside SRC, the source of a SET, find a base address. */
1332 find_base_value (rtx src
)
1336 #if defined (FIND_BASE_TERM)
1337 /* Try machine-dependent ways to find the base term. */
1338 src
= FIND_BASE_TERM (src
);
1341 switch (GET_CODE (src
))
1348 regno
= REGNO (src
);
1349 /* At the start of a function, argument registers have known base
1350 values which may be lost later. Returning an ADDRESS
1351 expression here allows optimization based on argument values
1352 even when the argument registers are used for other purposes. */
1353 if (regno
< FIRST_PSEUDO_REGISTER
&& copying_arguments
)
1354 return new_reg_base_value
[regno
];
1356 /* If a pseudo has a known base value, return it. Do not do this
1357 for non-fixed hard regs since it can result in a circular
1358 dependency chain for registers which have values at function entry.
1360 The test above is not sufficient because the scheduler may move
1361 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
1362 if ((regno
>= FIRST_PSEUDO_REGISTER
|| fixed_regs
[regno
])
1363 && regno
< vec_safe_length (reg_base_value
))
1365 /* If we're inside init_alias_analysis, use new_reg_base_value
1366 to reduce the number of relaxation iterations. */
1367 if (new_reg_base_value
&& new_reg_base_value
[regno
]
1368 && DF_REG_DEF_COUNT (regno
) == 1)
1369 return new_reg_base_value
[regno
];
1371 if ((*reg_base_value
)[regno
])
1372 return (*reg_base_value
)[regno
];
1378 /* Check for an argument passed in memory. Only record in the
1379 copying-arguments block; it is too hard to track changes
1381 if (copying_arguments
1382 && (XEXP (src
, 0) == arg_pointer_rtx
1383 || (GET_CODE (XEXP (src
, 0)) == PLUS
1384 && XEXP (XEXP (src
, 0), 0) == arg_pointer_rtx
)))
1385 return arg_base_value
;
1389 src
= XEXP (src
, 0);
1390 if (GET_CODE (src
) != PLUS
&& GET_CODE (src
) != MINUS
)
1393 /* ... fall through ... */
1398 rtx temp
, src_0
= XEXP (src
, 0), src_1
= XEXP (src
, 1);
1400 /* If either operand is a REG that is a known pointer, then it
1402 if (REG_P (src_0
) && REG_POINTER (src_0
))
1403 return find_base_value (src_0
);
1404 if (REG_P (src_1
) && REG_POINTER (src_1
))
1405 return find_base_value (src_1
);
1407 /* If either operand is a REG, then see if we already have
1408 a known value for it. */
1411 temp
= find_base_value (src_0
);
1418 temp
= find_base_value (src_1
);
1423 /* If either base is named object or a special address
1424 (like an argument or stack reference), then use it for the
1426 if (src_0
!= 0 && known_base_value_p (src_0
))
1429 if (src_1
!= 0 && known_base_value_p (src_1
))
1432 /* Guess which operand is the base address:
1433 If either operand is a symbol, then it is the base. If
1434 either operand is a CONST_INT, then the other is the base. */
1435 if (CONST_INT_P (src_1
) || CONSTANT_P (src_0
))
1436 return find_base_value (src_0
);
1437 else if (CONST_INT_P (src_0
) || CONSTANT_P (src_1
))
1438 return find_base_value (src_1
);
1444 /* The standard form is (lo_sum reg sym) so look only at the
1446 return find_base_value (XEXP (src
, 1));
1449 /* If the second operand is constant set the base
1450 address to the first operand. */
1451 if (CONST_INT_P (XEXP (src
, 1)) && INTVAL (XEXP (src
, 1)) != 0)
1452 return find_base_value (XEXP (src
, 0));
1456 /* As we do not know which address space the pointer is referring to, we can
1457 handle this only if the target does not support different pointer or
1458 address modes depending on the address space. */
1459 if (!target_default_pointer_address_modes_p ())
1461 if (GET_MODE_SIZE (GET_MODE (src
)) < GET_MODE_SIZE (Pmode
))
1471 return find_base_value (XEXP (src
, 0));
1474 case SIGN_EXTEND
: /* used for NT/Alpha pointers */
1475 /* As we do not know which address space the pointer is referring to, we can
1476 handle this only if the target does not support different pointer or
1477 address modes depending on the address space. */
1478 if (!target_default_pointer_address_modes_p ())
1482 rtx temp
= find_base_value (XEXP (src
, 0));
1484 if (temp
!= 0 && CONSTANT_P (temp
))
1485 temp
= convert_memory_address (Pmode
, temp
);
1497 /* Called from init_alias_analysis indirectly through note_stores,
1498 or directly if DEST is a register with a REG_NOALIAS note attached.
1499 SET is null in the latter case. */
1501 /* While scanning insns to find base values, reg_seen[N] is nonzero if
1502 register N has been set in this function. */
1503 static sbitmap reg_seen
;
1506 record_set (rtx dest
, const_rtx set
, void *data ATTRIBUTE_UNUSED
)
1515 regno
= REGNO (dest
);
1517 gcc_checking_assert (regno
< reg_base_value
->length ());
1519 n
= REG_NREGS (dest
);
1524 bitmap_set_bit (reg_seen
, regno
+ n
);
1525 new_reg_base_value
[regno
+ n
] = 0;
1532 /* A CLOBBER wipes out any old value but does not prevent a previously
1533 unset register from acquiring a base address (i.e. reg_seen is not
1535 if (GET_CODE (set
) == CLOBBER
)
1537 new_reg_base_value
[regno
] = 0;
1540 src
= SET_SRC (set
);
1544 /* There's a REG_NOALIAS note against DEST. */
1545 if (bitmap_bit_p (reg_seen
, regno
))
1547 new_reg_base_value
[regno
] = 0;
1550 bitmap_set_bit (reg_seen
, regno
);
1551 new_reg_base_value
[regno
] = unique_base_value (unique_id
++);
1555 /* If this is not the first set of REGNO, see whether the new value
1556 is related to the old one. There are two cases of interest:
1558 (1) The register might be assigned an entirely new value
1559 that has the same base term as the original set.
1561 (2) The set might be a simple self-modification that
1562 cannot change REGNO's base value.
1564 If neither case holds, reject the original base value as invalid.
1565 Note that the following situation is not detected:
1567 extern int x, y; int *p = &x; p += (&y-&x);
1569 ANSI C does not allow computing the difference of addresses
1570 of distinct top level objects. */
1571 if (new_reg_base_value
[regno
] != 0
1572 && find_base_value (src
) != new_reg_base_value
[regno
])
1573 switch (GET_CODE (src
))
1577 if (XEXP (src
, 0) != dest
&& XEXP (src
, 1) != dest
)
1578 new_reg_base_value
[regno
] = 0;
1581 /* If the value we add in the PLUS is also a valid base value,
1582 this might be the actual base value, and the original value
1585 rtx other
= NULL_RTX
;
1587 if (XEXP (src
, 0) == dest
)
1588 other
= XEXP (src
, 1);
1589 else if (XEXP (src
, 1) == dest
)
1590 other
= XEXP (src
, 0);
1592 if (! other
|| find_base_value (other
))
1593 new_reg_base_value
[regno
] = 0;
1597 if (XEXP (src
, 0) != dest
|| !CONST_INT_P (XEXP (src
, 1)))
1598 new_reg_base_value
[regno
] = 0;
1601 new_reg_base_value
[regno
] = 0;
1604 /* If this is the first set of a register, record the value. */
1605 else if ((regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
1606 && ! bitmap_bit_p (reg_seen
, regno
) && new_reg_base_value
[regno
] == 0)
1607 new_reg_base_value
[regno
] = find_base_value (src
);
1609 bitmap_set_bit (reg_seen
, regno
);
1612 /* Return REG_BASE_VALUE for REGNO. Selective scheduler uses this to avoid
1613 using hard registers with non-null REG_BASE_VALUE for renaming. */
1615 get_reg_base_value (unsigned int regno
)
1617 return (*reg_base_value
)[regno
];
1620 /* If a value is known for REGNO, return it. */
1623 get_reg_known_value (unsigned int regno
)
1625 if (regno
>= FIRST_PSEUDO_REGISTER
)
1627 regno
-= FIRST_PSEUDO_REGISTER
;
1628 if (regno
< vec_safe_length (reg_known_value
))
1629 return (*reg_known_value
)[regno
];
1637 set_reg_known_value (unsigned int regno
, rtx val
)
1639 if (regno
>= FIRST_PSEUDO_REGISTER
)
1641 regno
-= FIRST_PSEUDO_REGISTER
;
1642 if (regno
< vec_safe_length (reg_known_value
))
1643 (*reg_known_value
)[regno
] = val
;
1647 /* Similarly for reg_known_equiv_p. */
1650 get_reg_known_equiv_p (unsigned int regno
)
1652 if (regno
>= FIRST_PSEUDO_REGISTER
)
1654 regno
-= FIRST_PSEUDO_REGISTER
;
1655 if (regno
< vec_safe_length (reg_known_value
))
1656 return bitmap_bit_p (reg_known_equiv_p
, regno
);
1662 set_reg_known_equiv_p (unsigned int regno
, bool val
)
1664 if (regno
>= FIRST_PSEUDO_REGISTER
)
1666 regno
-= FIRST_PSEUDO_REGISTER
;
1667 if (regno
< vec_safe_length (reg_known_value
))
1670 bitmap_set_bit (reg_known_equiv_p
, regno
);
1672 bitmap_clear_bit (reg_known_equiv_p
, regno
);
1678 /* Returns a canonical version of X, from the point of view alias
1679 analysis. (For example, if X is a MEM whose address is a register,
1680 and the register has a known value (say a SYMBOL_REF), then a MEM
1681 whose address is the SYMBOL_REF is returned.) */
1686 /* Recursively look for equivalences. */
1687 if (REG_P (x
) && REGNO (x
) >= FIRST_PSEUDO_REGISTER
)
1689 rtx t
= get_reg_known_value (REGNO (x
));
1693 return canon_rtx (t
);
1696 if (GET_CODE (x
) == PLUS
)
1698 rtx x0
= canon_rtx (XEXP (x
, 0));
1699 rtx x1
= canon_rtx (XEXP (x
, 1));
1701 if (x0
!= XEXP (x
, 0) || x1
!= XEXP (x
, 1))
1703 if (CONST_INT_P (x0
))
1704 return plus_constant (GET_MODE (x
), x1
, INTVAL (x0
));
1705 else if (CONST_INT_P (x1
))
1706 return plus_constant (GET_MODE (x
), x0
, INTVAL (x1
));
1707 return gen_rtx_PLUS (GET_MODE (x
), x0
, x1
);
1711 /* This gives us much better alias analysis when called from
1712 the loop optimizer. Note we want to leave the original
1713 MEM alone, but need to return the canonicalized MEM with
1714 all the flags with their original values. */
1716 x
= replace_equiv_address_nv (x
, canon_rtx (XEXP (x
, 0)));
1721 /* Return 1 if X and Y are identical-looking rtx's.
1722 Expect that X and Y has been already canonicalized.
1724 We use the data in reg_known_value above to see if two registers with
1725 different numbers are, in fact, equivalent. */
1728 rtx_equal_for_memref_p (const_rtx x
, const_rtx y
)
1735 if (x
== 0 && y
== 0)
1737 if (x
== 0 || y
== 0)
1743 code
= GET_CODE (x
);
1744 /* Rtx's of different codes cannot be equal. */
1745 if (code
!= GET_CODE (y
))
1748 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1749 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1751 if (GET_MODE (x
) != GET_MODE (y
))
1754 /* Some RTL can be compared without a recursive examination. */
1758 return REGNO (x
) == REGNO (y
);
1761 return LABEL_REF_LABEL (x
) == LABEL_REF_LABEL (y
);
1764 return compare_base_symbol_refs (x
, y
) == 1;
1767 /* This is magic, don't go through canonicalization et al. */
1768 return rtx_equal_p (ENTRY_VALUE_EXP (x
), ENTRY_VALUE_EXP (y
));
1772 /* Pointer equality guarantees equality for these nodes. */
1779 /* canon_rtx knows how to handle plus. No need to canonicalize. */
1781 return ((rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0))
1782 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 1)))
1783 || (rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 1))
1784 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 0))));
1785 /* For commutative operations, the RTX match if the operand match in any
1786 order. Also handle the simple binary and unary cases without a loop. */
1787 if (COMMUTATIVE_P (x
))
1789 rtx xop0
= canon_rtx (XEXP (x
, 0));
1790 rtx yop0
= canon_rtx (XEXP (y
, 0));
1791 rtx yop1
= canon_rtx (XEXP (y
, 1));
1793 return ((rtx_equal_for_memref_p (xop0
, yop0
)
1794 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop1
))
1795 || (rtx_equal_for_memref_p (xop0
, yop1
)
1796 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop0
)));
1798 else if (NON_COMMUTATIVE_P (x
))
1800 return (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1801 canon_rtx (XEXP (y
, 0)))
1802 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)),
1803 canon_rtx (XEXP (y
, 1))));
1805 else if (UNARY_P (x
))
1806 return rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1807 canon_rtx (XEXP (y
, 0)));
1809 /* Compare the elements. If any pair of corresponding elements
1810 fail to match, return 0 for the whole things.
1812 Limit cases to types which actually appear in addresses. */
1814 fmt
= GET_RTX_FORMAT (code
);
1815 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1820 if (XINT (x
, i
) != XINT (y
, i
))
1825 /* Two vectors must have the same length. */
1826 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1829 /* And the corresponding elements must match. */
1830 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1831 if (rtx_equal_for_memref_p (canon_rtx (XVECEXP (x
, i
, j
)),
1832 canon_rtx (XVECEXP (y
, i
, j
))) == 0)
1837 if (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, i
)),
1838 canon_rtx (XEXP (y
, i
))) == 0)
1842 /* This can happen for asm operands. */
1844 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1848 /* This can happen for an asm which clobbers memory. */
1852 /* It is believed that rtx's at this level will never
1853 contain anything but integers and other rtx's,
1854 except for within LABEL_REFs and SYMBOL_REFs. */
1863 find_base_term (rtx x
)
1866 struct elt_loc_list
*l
, *f
;
1869 #if defined (FIND_BASE_TERM)
1870 /* Try machine-dependent ways to find the base term. */
1871 x
= FIND_BASE_TERM (x
);
1874 switch (GET_CODE (x
))
1877 return REG_BASE_VALUE (x
);
1880 /* As we do not know which address space the pointer is referring to, we can
1881 handle this only if the target does not support different pointer or
1882 address modes depending on the address space. */
1883 if (!target_default_pointer_address_modes_p ())
1885 if (GET_MODE_SIZE (GET_MODE (x
)) < GET_MODE_SIZE (Pmode
))
1895 return find_base_term (XEXP (x
, 0));
1898 case SIGN_EXTEND
: /* Used for Alpha/NT pointers */
1899 /* As we do not know which address space the pointer is referring to, we can
1900 handle this only if the target does not support different pointer or
1901 address modes depending on the address space. */
1902 if (!target_default_pointer_address_modes_p ())
1906 rtx temp
= find_base_term (XEXP (x
, 0));
1908 if (temp
!= 0 && CONSTANT_P (temp
))
1909 temp
= convert_memory_address (Pmode
, temp
);
1915 val
= CSELIB_VAL_PTR (x
);
1921 if (cselib_sp_based_value_p (val
))
1922 return static_reg_base_value
[STACK_POINTER_REGNUM
];
1925 /* Temporarily reset val->locs to avoid infinite recursion. */
1928 for (l
= f
; l
; l
= l
->next
)
1929 if (GET_CODE (l
->loc
) == VALUE
1930 && CSELIB_VAL_PTR (l
->loc
)->locs
1931 && !CSELIB_VAL_PTR (l
->loc
)->locs
->next
1932 && CSELIB_VAL_PTR (l
->loc
)->locs
->loc
== x
)
1934 else if ((ret
= find_base_term (l
->loc
)) != 0)
1941 /* The standard form is (lo_sum reg sym) so look only at the
1943 return find_base_term (XEXP (x
, 1));
1947 if (GET_CODE (x
) != PLUS
&& GET_CODE (x
) != MINUS
)
1953 rtx tmp1
= XEXP (x
, 0);
1954 rtx tmp2
= XEXP (x
, 1);
1956 /* This is a little bit tricky since we have to determine which of
1957 the two operands represents the real base address. Otherwise this
1958 routine may return the index register instead of the base register.
1960 That may cause us to believe no aliasing was possible, when in
1961 fact aliasing is possible.
1963 We use a few simple tests to guess the base register. Additional
1964 tests can certainly be added. For example, if one of the operands
1965 is a shift or multiply, then it must be the index register and the
1966 other operand is the base register. */
1968 if (tmp1
== pic_offset_table_rtx
&& CONSTANT_P (tmp2
))
1969 return find_base_term (tmp2
);
1971 /* If either operand is known to be a pointer, then prefer it
1972 to determine the base term. */
1973 if (REG_P (tmp1
) && REG_POINTER (tmp1
))
1975 else if (REG_P (tmp2
) && REG_POINTER (tmp2
))
1976 std::swap (tmp1
, tmp2
);
1977 /* If second argument is constant which has base term, prefer it
1978 over variable tmp1. See PR64025. */
1979 else if (CONSTANT_P (tmp2
) && !CONST_INT_P (tmp2
))
1980 std::swap (tmp1
, tmp2
);
1982 /* Go ahead and find the base term for both operands. If either base
1983 term is from a pointer or is a named object or a special address
1984 (like an argument or stack reference), then use it for the
1986 rtx base
= find_base_term (tmp1
);
1987 if (base
!= NULL_RTX
1988 && ((REG_P (tmp1
) && REG_POINTER (tmp1
))
1989 || known_base_value_p (base
)))
1991 base
= find_base_term (tmp2
);
1992 if (base
!= NULL_RTX
1993 && ((REG_P (tmp2
) && REG_POINTER (tmp2
))
1994 || known_base_value_p (base
)))
1997 /* We could not determine which of the two operands was the
1998 base register and which was the index. So we can determine
1999 nothing from the base alias check. */
2004 if (CONST_INT_P (XEXP (x
, 1)) && INTVAL (XEXP (x
, 1)) != 0)
2005 return find_base_term (XEXP (x
, 0));
2017 /* Return true if accesses to address X may alias accesses based
2018 on the stack pointer. */
2021 may_be_sp_based_p (rtx x
)
2023 rtx base
= find_base_term (x
);
2024 return !base
|| base
== static_reg_base_value
[STACK_POINTER_REGNUM
];
2027 /* BASE1 and BASE2 are decls. Return 1 if they refer to same object, 0
2028 if they refer to different objects and -1 if we can not decide. */
2031 compare_base_decls (tree base1
, tree base2
)
2034 gcc_checking_assert (DECL_P (base1
) && DECL_P (base2
));
2038 /* Declarations of non-automatic variables may have aliases. All other
2039 decls are unique. */
2040 if (!decl_in_symtab_p (base1
)
2041 || !decl_in_symtab_p (base2
))
2044 /* Don't cause symbols to be inserted by the act of checking. */
2045 symtab_node
*node1
= symtab_node::get (base1
);
2048 symtab_node
*node2
= symtab_node::get (base2
);
2052 ret
= node1
->equal_address_to (node2
, true);
2056 /* Same as compare_base_decls but for SYMBOL_REF. */
2059 compare_base_symbol_refs (const_rtx x_base
, const_rtx y_base
)
2061 tree x_decl
= SYMBOL_REF_DECL (x_base
);
2062 tree y_decl
= SYMBOL_REF_DECL (y_base
);
2063 bool binds_def
= true;
2065 if (XSTR (x_base
, 0) == XSTR (y_base
, 0))
2067 if (x_decl
&& y_decl
)
2068 return compare_base_decls (x_decl
, y_decl
);
2069 if (x_decl
|| y_decl
)
2073 std::swap (x_decl
, y_decl
);
2074 std::swap (x_base
, y_base
);
2076 /* We handle specially only section anchors and assume that other
2077 labels may overlap with user variables in an arbitrary way. */
2078 if (!SYMBOL_REF_HAS_BLOCK_INFO_P (y_base
))
2080 /* Anchors contains static VAR_DECLs and CONST_DECLs. We are safe
2081 to ignore CONST_DECLs because they are readonly. */
2082 if (TREE_CODE (x_decl
) != VAR_DECL
2083 || (!TREE_STATIC (x_decl
) && !TREE_PUBLIC (x_decl
)))
2086 symtab_node
*x_node
= symtab_node::get_create (x_decl
)
2087 ->ultimate_alias_target ();
2088 /* External variable can not be in section anchor. */
2089 if (!x_node
->definition
)
2091 x_base
= XEXP (DECL_RTL (x_node
->decl
), 0);
2092 /* If not in anchor, we can disambiguate. */
2093 if (!SYMBOL_REF_HAS_BLOCK_INFO_P (x_base
))
2096 /* We have an alias of anchored variable. If it can be interposed;
2097 we must assume it may or may not alias its anchor. */
2098 binds_def
= decl_binds_to_current_def_p (x_decl
);
2100 /* If we have variable in section anchor, we can compare by offset. */
2101 if (SYMBOL_REF_HAS_BLOCK_INFO_P (x_base
)
2102 && SYMBOL_REF_HAS_BLOCK_INFO_P (y_base
))
2104 if (SYMBOL_REF_BLOCK (x_base
) != SYMBOL_REF_BLOCK (y_base
))
2106 if (SYMBOL_REF_BLOCK_OFFSET (x_base
) == SYMBOL_REF_BLOCK_OFFSET (y_base
))
2107 return binds_def
? 1 : -1;
2108 if (SYMBOL_REF_ANCHOR_P (x_base
) != SYMBOL_REF_ANCHOR_P (y_base
))
2112 /* In general we assume that memory locations pointed to by different labels
2113 may overlap in undefined ways. */
2117 /* Return 0 if the addresses X and Y are known to point to different
2118 objects, 1 if they might be pointers to the same object. */
2121 base_alias_check (rtx x
, rtx x_base
, rtx y
, rtx y_base
,
2122 machine_mode x_mode
, machine_mode y_mode
)
2124 /* If the address itself has no known base see if a known equivalent
2125 value has one. If either address still has no known base, nothing
2126 is known about aliasing. */
2131 if (! flag_expensive_optimizations
|| (x_c
= canon_rtx (x
)) == x
)
2134 x_base
= find_base_term (x_c
);
2142 if (! flag_expensive_optimizations
|| (y_c
= canon_rtx (y
)) == y
)
2145 y_base
= find_base_term (y_c
);
2150 /* If the base addresses are equal nothing is known about aliasing. */
2151 if (rtx_equal_p (x_base
, y_base
))
2154 /* The base addresses are different expressions. If they are not accessed
2155 via AND, there is no conflict. We can bring knowledge of object
2156 alignment into play here. For example, on alpha, "char a, b;" can
2157 alias one another, though "char a; long b;" cannot. AND addesses may
2158 implicitly alias surrounding objects; i.e. unaligned access in DImode
2159 via AND address can alias all surrounding object types except those
2160 with aligment 8 or higher. */
2161 if (GET_CODE (x
) == AND
&& GET_CODE (y
) == AND
)
2163 if (GET_CODE (x
) == AND
2164 && (!CONST_INT_P (XEXP (x
, 1))
2165 || (int) GET_MODE_UNIT_SIZE (y_mode
) < -INTVAL (XEXP (x
, 1))))
2167 if (GET_CODE (y
) == AND
2168 && (!CONST_INT_P (XEXP (y
, 1))
2169 || (int) GET_MODE_UNIT_SIZE (x_mode
) < -INTVAL (XEXP (y
, 1))))
2172 /* Differing symbols not accessed via AND never alias. */
2173 if (GET_CODE (x_base
) == SYMBOL_REF
&& GET_CODE (y_base
) == SYMBOL_REF
)
2174 return compare_base_symbol_refs (x_base
, y_base
) != 0;
2176 if (GET_CODE (x_base
) != ADDRESS
&& GET_CODE (y_base
) != ADDRESS
)
2179 if (unique_base_value_p (x_base
) || unique_base_value_p (y_base
))
2185 /* Return TRUE if EXPR refers to a VALUE whose uid is greater than
2186 (or equal to) that of V. */
2189 refs_newer_value_p (const_rtx expr
, rtx v
)
2191 int minuid
= CSELIB_VAL_PTR (v
)->uid
;
2192 subrtx_iterator::array_type array
;
2193 FOR_EACH_SUBRTX (iter
, array
, expr
, NONCONST
)
2194 if (GET_CODE (*iter
) == VALUE
&& CSELIB_VAL_PTR (*iter
)->uid
>= minuid
)
2199 /* Convert the address X into something we can use. This is done by returning
2200 it unchanged unless it is a VALUE or VALUE +/- constant; for VALUE
2201 we call cselib to get a more useful rtx. */
2207 struct elt_loc_list
*l
;
2209 if (GET_CODE (x
) != VALUE
)
2211 if ((GET_CODE (x
) == PLUS
|| GET_CODE (x
) == MINUS
)
2212 && GET_CODE (XEXP (x
, 0)) == VALUE
2213 && CONST_SCALAR_INT_P (XEXP (x
, 1)))
2215 rtx op0
= get_addr (XEXP (x
, 0));
2216 if (op0
!= XEXP (x
, 0))
2218 if (GET_CODE (x
) == PLUS
2219 && GET_CODE (XEXP (x
, 1)) == CONST_INT
)
2220 return plus_constant (GET_MODE (x
), op0
, INTVAL (XEXP (x
, 1)));
2221 return simplify_gen_binary (GET_CODE (x
), GET_MODE (x
),
2227 v
= CSELIB_VAL_PTR (x
);
2230 bool have_equivs
= cselib_have_permanent_equivalences ();
2232 v
= canonical_cselib_val (v
);
2233 for (l
= v
->locs
; l
; l
= l
->next
)
2234 if (CONSTANT_P (l
->loc
))
2236 for (l
= v
->locs
; l
; l
= l
->next
)
2237 if (!REG_P (l
->loc
) && !MEM_P (l
->loc
)
2238 /* Avoid infinite recursion when potentially dealing with
2239 var-tracking artificial equivalences, by skipping the
2240 equivalences themselves, and not choosing expressions
2241 that refer to newer VALUEs. */
2243 || (GET_CODE (l
->loc
) != VALUE
2244 && !refs_newer_value_p (l
->loc
, x
))))
2248 for (l
= v
->locs
; l
; l
= l
->next
)
2250 || (GET_CODE (l
->loc
) != VALUE
2251 && !refs_newer_value_p (l
->loc
, x
)))
2253 /* Return the canonical value. */
2257 return v
->locs
->loc
;
2262 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
2263 where SIZE is the size in bytes of the memory reference. If ADDR
2264 is not modified by the memory reference then ADDR is returned. */
2267 addr_side_effect_eval (rtx addr
, int size
, int n_refs
)
2271 switch (GET_CODE (addr
))
2274 offset
= (n_refs
+ 1) * size
;
2277 offset
= -(n_refs
+ 1) * size
;
2280 offset
= n_refs
* size
;
2283 offset
= -n_refs
* size
;
2291 addr
= gen_rtx_PLUS (GET_MODE (addr
), XEXP (addr
, 0),
2292 gen_int_mode (offset
, GET_MODE (addr
)));
2294 addr
= XEXP (addr
, 0);
2295 addr
= canon_rtx (addr
);
2300 /* Return TRUE if an object X sized at XSIZE bytes and another object
2301 Y sized at YSIZE bytes, starting C bytes after X, may overlap. If
2302 any of the sizes is zero, assume an overlap, otherwise use the
2303 absolute value of the sizes as the actual sizes. */
2306 offset_overlap_p (HOST_WIDE_INT c
, int xsize
, int ysize
)
2308 return (xsize
== 0 || ysize
== 0
2311 : (abs (ysize
) > -c
)));
2314 /* Return one if X and Y (memory addresses) reference the
2315 same location in memory or if the references overlap.
2316 Return zero if they do not overlap, else return
2317 minus one in which case they still might reference the same location.
2319 C is an offset accumulator. When
2320 C is nonzero, we are testing aliases between X and Y + C.
2321 XSIZE is the size in bytes of the X reference,
2322 similarly YSIZE is the size in bytes for Y.
2323 Expect that canon_rtx has been already called for X and Y.
2325 If XSIZE or YSIZE is zero, we do not know the amount of memory being
2326 referenced (the reference was BLKmode), so make the most pessimistic
2329 If XSIZE or YSIZE is negative, we may access memory outside the object
2330 being referenced as a side effect. This can happen when using AND to
2331 align memory references, as is done on the Alpha.
2333 Nice to notice that varying addresses cannot conflict with fp if no
2334 local variables had their addresses taken, but that's too hard now.
2336 ??? Contrary to the tree alias oracle this does not return
2337 one for X + non-constant and Y + non-constant when X and Y are equal.
2338 If that is fixed the TBAA hack for union type-punning can be removed. */
2341 memrefs_conflict_p (int xsize
, rtx x
, int ysize
, rtx y
, HOST_WIDE_INT c
)
2343 if (GET_CODE (x
) == VALUE
)
2347 struct elt_loc_list
*l
= NULL
;
2348 if (CSELIB_VAL_PTR (x
))
2349 for (l
= canonical_cselib_val (CSELIB_VAL_PTR (x
))->locs
;
2351 if (REG_P (l
->loc
) && rtx_equal_for_memref_p (l
->loc
, y
))
2358 /* Don't call get_addr if y is the same VALUE. */
2362 if (GET_CODE (y
) == VALUE
)
2366 struct elt_loc_list
*l
= NULL
;
2367 if (CSELIB_VAL_PTR (y
))
2368 for (l
= canonical_cselib_val (CSELIB_VAL_PTR (y
))->locs
;
2370 if (REG_P (l
->loc
) && rtx_equal_for_memref_p (l
->loc
, x
))
2377 /* Don't call get_addr if x is the same VALUE. */
2381 if (GET_CODE (x
) == HIGH
)
2383 else if (GET_CODE (x
) == LO_SUM
)
2386 x
= addr_side_effect_eval (x
, abs (xsize
), 0);
2387 if (GET_CODE (y
) == HIGH
)
2389 else if (GET_CODE (y
) == LO_SUM
)
2392 y
= addr_side_effect_eval (y
, abs (ysize
), 0);
2394 if (GET_CODE (x
) == SYMBOL_REF
&& GET_CODE (y
) == SYMBOL_REF
)
2396 int cmp
= compare_base_symbol_refs (x
,y
);
2398 /* If both decls are the same, decide by offsets. */
2400 return offset_overlap_p (c
, xsize
, ysize
);
2401 /* Assume a potential overlap for symbolic addresses that went
2402 through alignment adjustments (i.e., that have negative
2403 sizes), because we can't know how far they are from each
2405 if (xsize
< 0 || ysize
< 0)
2407 /* If decls are different or we know by offsets that there is no overlap,
2409 if (!cmp
|| !offset_overlap_p (c
, xsize
, ysize
))
2411 /* Decls may or may not be different and offsets overlap....*/
2414 else if (rtx_equal_for_memref_p (x
, y
))
2416 return offset_overlap_p (c
, xsize
, ysize
);
2419 /* This code used to check for conflicts involving stack references and
2420 globals but the base address alias code now handles these cases. */
2422 if (GET_CODE (x
) == PLUS
)
2424 /* The fact that X is canonicalized means that this
2425 PLUS rtx is canonicalized. */
2426 rtx x0
= XEXP (x
, 0);
2427 rtx x1
= XEXP (x
, 1);
2429 /* However, VALUEs might end up in different positions even in
2430 canonical PLUSes. Comparing their addresses is enough. */
2432 return memrefs_conflict_p (xsize
, x1
, ysize
, const0_rtx
, c
);
2434 return memrefs_conflict_p (xsize
, x0
, ysize
, const0_rtx
, c
);
2436 if (GET_CODE (y
) == PLUS
)
2438 /* The fact that Y is canonicalized means that this
2439 PLUS rtx is canonicalized. */
2440 rtx y0
= XEXP (y
, 0);
2441 rtx y1
= XEXP (y
, 1);
2444 return memrefs_conflict_p (xsize
, x1
, ysize
, y0
, c
);
2446 return memrefs_conflict_p (xsize
, x0
, ysize
, y1
, c
);
2448 if (rtx_equal_for_memref_p (x1
, y1
))
2449 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
2450 if (rtx_equal_for_memref_p (x0
, y0
))
2451 return memrefs_conflict_p (xsize
, x1
, ysize
, y1
, c
);
2452 if (CONST_INT_P (x1
))
2454 if (CONST_INT_P (y1
))
2455 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
,
2456 c
- INTVAL (x1
) + INTVAL (y1
));
2458 return memrefs_conflict_p (xsize
, x0
, ysize
, y
,
2461 else if (CONST_INT_P (y1
))
2462 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
2466 else if (CONST_INT_P (x1
))
2467 return memrefs_conflict_p (xsize
, x0
, ysize
, y
, c
- INTVAL (x1
));
2469 else if (GET_CODE (y
) == PLUS
)
2471 /* The fact that Y is canonicalized means that this
2472 PLUS rtx is canonicalized. */
2473 rtx y0
= XEXP (y
, 0);
2474 rtx y1
= XEXP (y
, 1);
2477 return memrefs_conflict_p (xsize
, const0_rtx
, ysize
, y1
, c
);
2479 return memrefs_conflict_p (xsize
, const0_rtx
, ysize
, y0
, c
);
2481 if (CONST_INT_P (y1
))
2482 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
2487 if (GET_CODE (x
) == GET_CODE (y
))
2488 switch (GET_CODE (x
))
2492 /* Handle cases where we expect the second operands to be the
2493 same, and check only whether the first operand would conflict
2496 rtx x1
= canon_rtx (XEXP (x
, 1));
2497 rtx y1
= canon_rtx (XEXP (y
, 1));
2498 if (! rtx_equal_for_memref_p (x1
, y1
))
2500 x0
= canon_rtx (XEXP (x
, 0));
2501 y0
= canon_rtx (XEXP (y
, 0));
2502 if (rtx_equal_for_memref_p (x0
, y0
))
2503 return offset_overlap_p (c
, xsize
, ysize
);
2505 /* Can't properly adjust our sizes. */
2506 if (!CONST_INT_P (x1
))
2508 xsize
/= INTVAL (x1
);
2509 ysize
/= INTVAL (x1
);
2511 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
2518 /* Deal with alignment ANDs by adjusting offset and size so as to
2519 cover the maximum range, without taking any previously known
2520 alignment into account. Make a size negative after such an
2521 adjustments, so that, if we end up with e.g. two SYMBOL_REFs, we
2522 assume a potential overlap, because they may end up in contiguous
2523 memory locations and the stricter-alignment access may span over
2525 if (GET_CODE (x
) == AND
&& CONST_INT_P (XEXP (x
, 1)))
2527 HOST_WIDE_INT sc
= INTVAL (XEXP (x
, 1));
2528 unsigned HOST_WIDE_INT uc
= sc
;
2529 if (sc
< 0 && -uc
== (uc
& -uc
))
2536 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2540 if (GET_CODE (y
) == AND
&& CONST_INT_P (XEXP (y
, 1)))
2542 HOST_WIDE_INT sc
= INTVAL (XEXP (y
, 1));
2543 unsigned HOST_WIDE_INT uc
= sc
;
2544 if (sc
< 0 && -uc
== (uc
& -uc
))
2551 return memrefs_conflict_p (xsize
, x
,
2552 ysize
, canon_rtx (XEXP (y
, 0)), c
);
2558 if (CONST_INT_P (x
) && CONST_INT_P (y
))
2560 c
+= (INTVAL (y
) - INTVAL (x
));
2561 return offset_overlap_p (c
, xsize
, ysize
);
2564 if (GET_CODE (x
) == CONST
)
2566 if (GET_CODE (y
) == CONST
)
2567 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2568 ysize
, canon_rtx (XEXP (y
, 0)), c
);
2570 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2573 if (GET_CODE (y
) == CONST
)
2574 return memrefs_conflict_p (xsize
, x
, ysize
,
2575 canon_rtx (XEXP (y
, 0)), c
);
2577 /* Assume a potential overlap for symbolic addresses that went
2578 through alignment adjustments (i.e., that have negative
2579 sizes), because we can't know how far they are from each
2582 return (xsize
< 0 || ysize
< 0 || offset_overlap_p (c
, xsize
, ysize
));
2590 /* Functions to compute memory dependencies.
2592 Since we process the insns in execution order, we can build tables
2593 to keep track of what registers are fixed (and not aliased), what registers
2594 are varying in known ways, and what registers are varying in unknown
2597 If both memory references are volatile, then there must always be a
2598 dependence between the two references, since their order can not be
2599 changed. A volatile and non-volatile reference can be interchanged
2602 We also must allow AND addresses, because they may generate accesses
2603 outside the object being referenced. This is used to generate aligned
2604 addresses from unaligned addresses, for instance, the alpha
2605 storeqi_unaligned pattern. */
2607 /* Read dependence: X is read after read in MEM takes place. There can
2608 only be a dependence here if both reads are volatile, or if either is
2609 an explicit barrier. */
2612 read_dependence (const_rtx mem
, const_rtx x
)
2614 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2616 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2617 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2622 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
2625 decl_for_component_ref (tree x
)
2629 x
= TREE_OPERAND (x
, 0);
2631 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
2633 return x
&& DECL_P (x
) ? x
: NULL_TREE
;
2636 /* Walk up the COMPONENT_REF list in X and adjust *OFFSET to compensate
2637 for the offset of the field reference. *KNOWN_P says whether the
2641 adjust_offset_for_component_ref (tree x
, bool *known_p
,
2642 HOST_WIDE_INT
*offset
)
2648 tree xoffset
= component_ref_field_offset (x
);
2649 tree field
= TREE_OPERAND (x
, 1);
2650 if (TREE_CODE (xoffset
) != INTEGER_CST
)
2657 = (wi::to_offset (xoffset
)
2658 + wi::lrshift (wi::to_offset (DECL_FIELD_BIT_OFFSET (field
)),
2659 LOG2_BITS_PER_UNIT
));
2660 if (!wi::fits_uhwi_p (woffset
))
2665 *offset
+= woffset
.to_uhwi ();
2667 x
= TREE_OPERAND (x
, 0);
2669 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
2672 /* Return nonzero if we can determine the exprs corresponding to memrefs
2673 X and Y and they do not overlap.
2674 If LOOP_VARIANT is set, skip offset-based disambiguation */
2677 nonoverlapping_memrefs_p (const_rtx x
, const_rtx y
, bool loop_invariant
)
2679 tree exprx
= MEM_EXPR (x
), expry
= MEM_EXPR (y
);
2682 bool moffsetx_known_p
, moffsety_known_p
;
2683 HOST_WIDE_INT moffsetx
= 0, moffsety
= 0;
2684 HOST_WIDE_INT offsetx
= 0, offsety
= 0, sizex
, sizey
;
2686 /* Unless both have exprs, we can't tell anything. */
2687 if (exprx
== 0 || expry
== 0)
2690 /* For spill-slot accesses make sure we have valid offsets. */
2691 if ((exprx
== get_spill_slot_decl (false)
2692 && ! MEM_OFFSET_KNOWN_P (x
))
2693 || (expry
== get_spill_slot_decl (false)
2694 && ! MEM_OFFSET_KNOWN_P (y
)))
2697 /* If the field reference test failed, look at the DECLs involved. */
2698 moffsetx_known_p
= MEM_OFFSET_KNOWN_P (x
);
2699 if (moffsetx_known_p
)
2700 moffsetx
= MEM_OFFSET (x
);
2701 if (TREE_CODE (exprx
) == COMPONENT_REF
)
2703 tree t
= decl_for_component_ref (exprx
);
2706 adjust_offset_for_component_ref (exprx
, &moffsetx_known_p
, &moffsetx
);
2710 moffsety_known_p
= MEM_OFFSET_KNOWN_P (y
);
2711 if (moffsety_known_p
)
2712 moffsety
= MEM_OFFSET (y
);
2713 if (TREE_CODE (expry
) == COMPONENT_REF
)
2715 tree t
= decl_for_component_ref (expry
);
2718 adjust_offset_for_component_ref (expry
, &moffsety_known_p
, &moffsety
);
2722 if (! DECL_P (exprx
) || ! DECL_P (expry
))
2725 /* If we refer to different gimple registers, or one gimple register
2726 and one non-gimple-register, we know they can't overlap. First,
2727 gimple registers don't have their addresses taken. Now, there
2728 could be more than one stack slot for (different versions of) the
2729 same gimple register, but we can presumably tell they don't
2730 overlap based on offsets from stack base addresses elsewhere.
2731 It's important that we don't proceed to DECL_RTL, because gimple
2732 registers may not pass DECL_RTL_SET_P, and make_decl_rtl won't be
2733 able to do anything about them since no SSA information will have
2734 remained to guide it. */
2735 if (is_gimple_reg (exprx
) || is_gimple_reg (expry
))
2736 return exprx
!= expry
2737 || (moffsetx_known_p
&& moffsety_known_p
2738 && MEM_SIZE_KNOWN_P (x
) && MEM_SIZE_KNOWN_P (y
)
2739 && !offset_overlap_p (moffsety
- moffsetx
,
2740 MEM_SIZE (x
), MEM_SIZE (y
)));
2742 /* With invalid code we can end up storing into the constant pool.
2743 Bail out to avoid ICEing when creating RTL for this.
2744 See gfortran.dg/lto/20091028-2_0.f90. */
2745 if (TREE_CODE (exprx
) == CONST_DECL
2746 || TREE_CODE (expry
) == CONST_DECL
)
2749 rtlx
= DECL_RTL (exprx
);
2750 rtly
= DECL_RTL (expry
);
2752 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
2753 can't overlap unless they are the same because we never reuse that part
2754 of the stack frame used for locals for spilled pseudos. */
2755 if ((!MEM_P (rtlx
) || !MEM_P (rtly
))
2756 && ! rtx_equal_p (rtlx
, rtly
))
2759 /* If we have MEMs referring to different address spaces (which can
2760 potentially overlap), we cannot easily tell from the addresses
2761 whether the references overlap. */
2762 if (MEM_P (rtlx
) && MEM_P (rtly
)
2763 && MEM_ADDR_SPACE (rtlx
) != MEM_ADDR_SPACE (rtly
))
2766 /* Get the base and offsets of both decls. If either is a register, we
2767 know both are and are the same, so use that as the base. The only
2768 we can avoid overlap is if we can deduce that they are nonoverlapping
2769 pieces of that decl, which is very rare. */
2770 basex
= MEM_P (rtlx
) ? XEXP (rtlx
, 0) : rtlx
;
2771 if (GET_CODE (basex
) == PLUS
&& CONST_INT_P (XEXP (basex
, 1)))
2772 offsetx
= INTVAL (XEXP (basex
, 1)), basex
= XEXP (basex
, 0);
2774 basey
= MEM_P (rtly
) ? XEXP (rtly
, 0) : rtly
;
2775 if (GET_CODE (basey
) == PLUS
&& CONST_INT_P (XEXP (basey
, 1)))
2776 offsety
= INTVAL (XEXP (basey
, 1)), basey
= XEXP (basey
, 0);
2778 /* If the bases are different, we know they do not overlap if both
2779 are constants or if one is a constant and the other a pointer into the
2780 stack frame. Otherwise a different base means we can't tell if they
2782 if (compare_base_decls (exprx
, expry
) == 0)
2783 return ((CONSTANT_P (basex
) && CONSTANT_P (basey
))
2784 || (CONSTANT_P (basex
) && REG_P (basey
)
2785 && REGNO_PTR_FRAME_P (REGNO (basey
)))
2786 || (CONSTANT_P (basey
) && REG_P (basex
)
2787 && REGNO_PTR_FRAME_P (REGNO (basex
))));
2789 /* Offset based disambiguation not appropriate for loop invariant */
2793 /* Offset based disambiguation is OK even if we do not know that the
2794 declarations are necessarily different
2795 (i.e. compare_base_decls (exprx, expry) == -1) */
2797 sizex
= (!MEM_P (rtlx
) ? (int) GET_MODE_SIZE (GET_MODE (rtlx
))
2798 : MEM_SIZE_KNOWN_P (rtlx
) ? MEM_SIZE (rtlx
)
2800 sizey
= (!MEM_P (rtly
) ? (int) GET_MODE_SIZE (GET_MODE (rtly
))
2801 : MEM_SIZE_KNOWN_P (rtly
) ? MEM_SIZE (rtly
)
2804 /* If we have an offset for either memref, it can update the values computed
2806 if (moffsetx_known_p
)
2807 offsetx
+= moffsetx
, sizex
-= moffsetx
;
2808 if (moffsety_known_p
)
2809 offsety
+= moffsety
, sizey
-= moffsety
;
2811 /* If a memref has both a size and an offset, we can use the smaller size.
2812 We can't do this if the offset isn't known because we must view this
2813 memref as being anywhere inside the DECL's MEM. */
2814 if (MEM_SIZE_KNOWN_P (x
) && moffsetx_known_p
)
2815 sizex
= MEM_SIZE (x
);
2816 if (MEM_SIZE_KNOWN_P (y
) && moffsety_known_p
)
2817 sizey
= MEM_SIZE (y
);
2819 /* Put the values of the memref with the lower offset in X's values. */
2820 if (offsetx
> offsety
)
2822 std::swap (offsetx
, offsety
);
2823 std::swap (sizex
, sizey
);
2826 /* If we don't know the size of the lower-offset value, we can't tell
2827 if they conflict. Otherwise, we do the test. */
2828 return sizex
>= 0 && offsety
>= offsetx
+ sizex
;
2831 /* Helper for true_dependence and canon_true_dependence.
2832 Checks for true dependence: X is read after store in MEM takes place.
2834 If MEM_CANONICALIZED is FALSE, then X_ADDR and MEM_ADDR should be
2835 NULL_RTX, and the canonical addresses of MEM and X are both computed
2836 here. If MEM_CANONICALIZED, then MEM must be already canonicalized.
2838 If X_ADDR is non-NULL, it is used in preference of XEXP (x, 0).
2840 Returns 1 if there is a true dependence, 0 otherwise. */
2843 true_dependence_1 (const_rtx mem
, machine_mode mem_mode
, rtx mem_addr
,
2844 const_rtx x
, rtx x_addr
, bool mem_canonicalized
)
2850 gcc_checking_assert (mem_canonicalized
? (mem_addr
!= NULL_RTX
)
2851 : (mem_addr
== NULL_RTX
&& x_addr
== NULL_RTX
));
2853 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2856 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2857 This is used in epilogue deallocation functions, and in cselib. */
2858 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2860 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2862 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2863 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2867 x_addr
= XEXP (x
, 0);
2868 x_addr
= get_addr (x_addr
);
2872 mem_addr
= XEXP (mem
, 0);
2873 if (mem_mode
== VOIDmode
)
2874 mem_mode
= GET_MODE (mem
);
2876 true_mem_addr
= get_addr (mem_addr
);
2878 /* Read-only memory is by definition never modified, and therefore can't
2879 conflict with anything. However, don't assume anything when AND
2880 addresses are involved and leave to the code below to determine
2881 dependence. We don't expect to find read-only set on MEM, but
2882 stupid user tricks can produce them, so don't die. */
2883 if (MEM_READONLY_P (x
)
2884 && GET_CODE (x_addr
) != AND
2885 && GET_CODE (true_mem_addr
) != AND
)
2888 /* If we have MEMs referring to different address spaces (which can
2889 potentially overlap), we cannot easily tell from the addresses
2890 whether the references overlap. */
2891 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
2894 base
= find_base_term (x_addr
);
2895 if (base
&& (GET_CODE (base
) == LABEL_REF
2896 || (GET_CODE (base
) == SYMBOL_REF
2897 && CONSTANT_POOL_ADDRESS_P (base
))))
2900 rtx mem_base
= find_base_term (true_mem_addr
);
2901 if (! base_alias_check (x_addr
, base
, true_mem_addr
, mem_base
,
2902 GET_MODE (x
), mem_mode
))
2905 x_addr
= canon_rtx (x_addr
);
2906 if (!mem_canonicalized
)
2907 mem_addr
= canon_rtx (true_mem_addr
);
2909 if ((ret
= memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
2910 SIZE_FOR_MODE (x
), x_addr
, 0)) != -1)
2913 if (mems_in_disjoint_alias_sets_p (x
, mem
))
2916 if (nonoverlapping_memrefs_p (mem
, x
, false))
2919 return rtx_refs_may_alias_p (x
, mem
, true);
2922 /* True dependence: X is read after store in MEM takes place. */
2925 true_dependence (const_rtx mem
, machine_mode mem_mode
, const_rtx x
)
2927 return true_dependence_1 (mem
, mem_mode
, NULL_RTX
,
2928 x
, NULL_RTX
, /*mem_canonicalized=*/false);
2931 /* Canonical true dependence: X is read after store in MEM takes place.
2932 Variant of true_dependence which assumes MEM has already been
2933 canonicalized (hence we no longer do that here).
2934 The mem_addr argument has been added, since true_dependence_1 computed
2935 this value prior to canonicalizing. */
2938 canon_true_dependence (const_rtx mem
, machine_mode mem_mode
, rtx mem_addr
,
2939 const_rtx x
, rtx x_addr
)
2941 return true_dependence_1 (mem
, mem_mode
, mem_addr
,
2942 x
, x_addr
, /*mem_canonicalized=*/true);
2945 /* Returns nonzero if a write to X might alias a previous read from
2946 (or, if WRITEP is true, a write to) MEM.
2947 If X_CANONCALIZED is true, then X_ADDR is the canonicalized address of X,
2948 and X_MODE the mode for that access.
2949 If MEM_CANONICALIZED is true, MEM is canonicalized. */
2952 write_dependence_p (const_rtx mem
,
2953 const_rtx x
, machine_mode x_mode
, rtx x_addr
,
2954 bool mem_canonicalized
, bool x_canonicalized
, bool writep
)
2957 rtx true_mem_addr
, true_x_addr
;
2961 gcc_checking_assert (x_canonicalized
2962 ? (x_addr
!= NULL_RTX
&& x_mode
!= VOIDmode
)
2963 : (x_addr
== NULL_RTX
&& x_mode
== VOIDmode
));
2965 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2968 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2969 This is used in epilogue deallocation functions. */
2970 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2972 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2974 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2975 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2979 x_addr
= XEXP (x
, 0);
2980 true_x_addr
= get_addr (x_addr
);
2982 mem_addr
= XEXP (mem
, 0);
2983 true_mem_addr
= get_addr (mem_addr
);
2985 /* A read from read-only memory can't conflict with read-write memory.
2986 Don't assume anything when AND addresses are involved and leave to
2987 the code below to determine dependence. */
2989 && MEM_READONLY_P (mem
)
2990 && GET_CODE (true_x_addr
) != AND
2991 && GET_CODE (true_mem_addr
) != AND
)
2994 /* If we have MEMs referring to different address spaces (which can
2995 potentially overlap), we cannot easily tell from the addresses
2996 whether the references overlap. */
2997 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
3000 base
= find_base_term (true_mem_addr
);
3003 && (GET_CODE (base
) == LABEL_REF
3004 || (GET_CODE (base
) == SYMBOL_REF
3005 && CONSTANT_POOL_ADDRESS_P (base
))))
3008 rtx x_base
= find_base_term (true_x_addr
);
3009 if (! base_alias_check (true_x_addr
, x_base
, true_mem_addr
, base
,
3010 GET_MODE (x
), GET_MODE (mem
)))
3013 if (!x_canonicalized
)
3015 x_addr
= canon_rtx (true_x_addr
);
3016 x_mode
= GET_MODE (x
);
3018 if (!mem_canonicalized
)
3019 mem_addr
= canon_rtx (true_mem_addr
);
3021 if ((ret
= memrefs_conflict_p (SIZE_FOR_MODE (mem
), mem_addr
,
3022 GET_MODE_SIZE (x_mode
), x_addr
, 0)) != -1)
3025 if (nonoverlapping_memrefs_p (x
, mem
, false))
3028 return rtx_refs_may_alias_p (x
, mem
, false);
3031 /* Anti dependence: X is written after read in MEM takes place. */
3034 anti_dependence (const_rtx mem
, const_rtx x
)
3036 return write_dependence_p (mem
, x
, VOIDmode
, NULL_RTX
,
3037 /*mem_canonicalized=*/false,
3038 /*x_canonicalized*/false, /*writep=*/false);
3041 /* Likewise, but we already have a canonicalized MEM, and X_ADDR for X.
3042 Also, consider X in X_MODE (which might be from an enclosing
3043 STRICT_LOW_PART / ZERO_EXTRACT).
3044 If MEM_CANONICALIZED is true, MEM is canonicalized. */
3047 canon_anti_dependence (const_rtx mem
, bool mem_canonicalized
,
3048 const_rtx x
, machine_mode x_mode
, rtx x_addr
)
3050 return write_dependence_p (mem
, x
, x_mode
, x_addr
,
3051 mem_canonicalized
, /*x_canonicalized=*/true,
3055 /* Output dependence: X is written after store in MEM takes place. */
3058 output_dependence (const_rtx mem
, const_rtx x
)
3060 return write_dependence_p (mem
, x
, VOIDmode
, NULL_RTX
,
3061 /*mem_canonicalized=*/false,
3062 /*x_canonicalized*/false, /*writep=*/true);
3065 /* Likewise, but we already have a canonicalized MEM, and X_ADDR for X.
3066 Also, consider X in X_MODE (which might be from an enclosing
3067 STRICT_LOW_PART / ZERO_EXTRACT).
3068 If MEM_CANONICALIZED is true, MEM is canonicalized. */
3071 canon_output_dependence (const_rtx mem
, bool mem_canonicalized
,
3072 const_rtx x
, machine_mode x_mode
, rtx x_addr
)
3074 return write_dependence_p (mem
, x
, x_mode
, x_addr
,
3075 mem_canonicalized
, /*x_canonicalized=*/true,
3081 /* Check whether X may be aliased with MEM. Don't do offset-based
3082 memory disambiguation & TBAA. */
3084 may_alias_p (const_rtx mem
, const_rtx x
)
3086 rtx x_addr
, mem_addr
;
3088 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
3091 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
3092 This is used in epilogue deallocation functions. */
3093 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
3095 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
3097 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
3098 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
3101 x_addr
= XEXP (x
, 0);
3102 x_addr
= get_addr (x_addr
);
3104 mem_addr
= XEXP (mem
, 0);
3105 mem_addr
= get_addr (mem_addr
);
3107 /* Read-only memory is by definition never modified, and therefore can't
3108 conflict with anything. However, don't assume anything when AND
3109 addresses are involved and leave to the code below to determine
3110 dependence. We don't expect to find read-only set on MEM, but
3111 stupid user tricks can produce them, so don't die. */
3112 if (MEM_READONLY_P (x
)
3113 && GET_CODE (x_addr
) != AND
3114 && GET_CODE (mem_addr
) != AND
)
3117 /* If we have MEMs referring to different address spaces (which can
3118 potentially overlap), we cannot easily tell from the addresses
3119 whether the references overlap. */
3120 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
3123 rtx x_base
= find_base_term (x_addr
);
3124 rtx mem_base
= find_base_term (mem_addr
);
3125 if (! base_alias_check (x_addr
, x_base
, mem_addr
, mem_base
,
3126 GET_MODE (x
), GET_MODE (mem_addr
)))
3129 if (nonoverlapping_memrefs_p (mem
, x
, true))
3132 /* TBAA not valid for loop_invarint */
3133 return rtx_refs_may_alias_p (x
, mem
, false);
3137 init_alias_target (void)
3141 if (!arg_base_value
)
3142 arg_base_value
= gen_rtx_ADDRESS (VOIDmode
, 0);
3144 memset (static_reg_base_value
, 0, sizeof static_reg_base_value
);
3146 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3147 /* Check whether this register can hold an incoming pointer
3148 argument. FUNCTION_ARG_REGNO_P tests outgoing register
3149 numbers, so translate if necessary due to register windows. */
3150 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i
))
3151 && HARD_REGNO_MODE_OK (i
, Pmode
))
3152 static_reg_base_value
[i
] = arg_base_value
;
3154 static_reg_base_value
[STACK_POINTER_REGNUM
]
3155 = unique_base_value (UNIQUE_BASE_VALUE_SP
);
3156 static_reg_base_value
[ARG_POINTER_REGNUM
]
3157 = unique_base_value (UNIQUE_BASE_VALUE_ARGP
);
3158 static_reg_base_value
[FRAME_POINTER_REGNUM
]
3159 = unique_base_value (UNIQUE_BASE_VALUE_FP
);
3160 if (!HARD_FRAME_POINTER_IS_FRAME_POINTER
)
3161 static_reg_base_value
[HARD_FRAME_POINTER_REGNUM
]
3162 = unique_base_value (UNIQUE_BASE_VALUE_HFP
);
3165 /* Set MEMORY_MODIFIED when X modifies DATA (that is assumed
3166 to be memory reference. */
3167 static bool memory_modified
;
3169 memory_modified_1 (rtx x
, const_rtx pat ATTRIBUTE_UNUSED
, void *data
)
3173 if (anti_dependence (x
, (const_rtx
)data
) || output_dependence (x
, (const_rtx
)data
))
3174 memory_modified
= true;
3179 /* Return true when INSN possibly modify memory contents of MEM
3180 (i.e. address can be modified). */
3182 memory_modified_in_insn_p (const_rtx mem
, const_rtx insn
)
3186 memory_modified
= false;
3187 note_stores (PATTERN (insn
), memory_modified_1
, CONST_CAST_RTX(mem
));
3188 return memory_modified
;
3191 /* Return TRUE if the destination of a set is rtx identical to
3194 set_dest_equal_p (const_rtx set
, const_rtx item
)
3196 rtx dest
= SET_DEST (set
);
3197 return rtx_equal_p (dest
, item
);
3200 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
3204 init_alias_analysis (void)
3206 unsigned int maxreg
= max_reg_num ();
3215 timevar_push (TV_ALIAS_ANALYSIS
);
3217 vec_safe_grow_cleared (reg_known_value
, maxreg
- FIRST_PSEUDO_REGISTER
);
3218 reg_known_equiv_p
= sbitmap_alloc (maxreg
- FIRST_PSEUDO_REGISTER
);
3219 bitmap_clear (reg_known_equiv_p
);
3221 /* If we have memory allocated from the previous run, use it. */
3222 if (old_reg_base_value
)
3223 reg_base_value
= old_reg_base_value
;
3226 reg_base_value
->truncate (0);
3228 vec_safe_grow_cleared (reg_base_value
, maxreg
);
3230 new_reg_base_value
= XNEWVEC (rtx
, maxreg
);
3231 reg_seen
= sbitmap_alloc (maxreg
);
3233 /* The basic idea is that each pass through this loop will use the
3234 "constant" information from the previous pass to propagate alias
3235 information through another level of assignments.
3237 The propagation is done on the CFG in reverse post-order, to propagate
3238 things forward as far as possible in each iteration.
3240 This could get expensive if the assignment chains are long. Maybe
3241 we should throttle the number of iterations, possibly based on
3242 the optimization level or flag_expensive_optimizations.
3244 We could propagate more information in the first pass by making use
3245 of DF_REG_DEF_COUNT to determine immediately that the alias information
3246 for a pseudo is "constant".
3248 A program with an uninitialized variable can cause an infinite loop
3249 here. Instead of doing a full dataflow analysis to detect such problems
3250 we just cap the number of iterations for the loop.
3252 The state of the arrays for the set chain in question does not matter
3253 since the program has undefined behavior. */
3255 rpo
= XNEWVEC (int, n_basic_blocks_for_fn (cfun
));
3256 rpo_cnt
= pre_and_rev_post_order_compute (NULL
, rpo
, false);
3258 /* The prologue/epilogue insns are not threaded onto the
3259 insn chain until after reload has completed. Thus,
3260 there is no sense wasting time checking if INSN is in
3261 the prologue/epilogue until after reload has completed. */
3262 bool could_be_prologue_epilogue
= ((targetm
.have_prologue ()
3263 || targetm
.have_epilogue ())
3264 && reload_completed
);
3269 /* Assume nothing will change this iteration of the loop. */
3272 /* We want to assign the same IDs each iteration of this loop, so
3273 start counting from one each iteration of the loop. */
3276 /* We're at the start of the function each iteration through the
3277 loop, so we're copying arguments. */
3278 copying_arguments
= true;
3280 /* Wipe the potential alias information clean for this pass. */
3281 memset (new_reg_base_value
, 0, maxreg
* sizeof (rtx
));
3283 /* Wipe the reg_seen array clean. */
3284 bitmap_clear (reg_seen
);
3286 /* Initialize the alias information for this pass. */
3287 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3288 if (static_reg_base_value
[i
])
3290 new_reg_base_value
[i
] = static_reg_base_value
[i
];
3291 bitmap_set_bit (reg_seen
, i
);
3294 /* Walk the insns adding values to the new_reg_base_value array. */
3295 for (i
= 0; i
< rpo_cnt
; i
++)
3297 basic_block bb
= BASIC_BLOCK_FOR_FN (cfun
, rpo
[i
]);
3298 FOR_BB_INSNS (bb
, insn
)
3300 if (NONDEBUG_INSN_P (insn
))
3304 if (could_be_prologue_epilogue
3305 && prologue_epilogue_contains (insn
))
3308 /* If this insn has a noalias note, process it, Otherwise,
3309 scan for sets. A simple set will have no side effects
3310 which could change the base value of any other register. */
3312 if (GET_CODE (PATTERN (insn
)) == SET
3313 && REG_NOTES (insn
) != 0
3314 && find_reg_note (insn
, REG_NOALIAS
, NULL_RTX
))
3315 record_set (SET_DEST (PATTERN (insn
)), NULL_RTX
, NULL
);
3317 note_stores (PATTERN (insn
), record_set
, NULL
);
3319 set
= single_set (insn
);
3322 && REG_P (SET_DEST (set
))
3323 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
)
3325 unsigned int regno
= REGNO (SET_DEST (set
));
3326 rtx src
= SET_SRC (set
);
3329 note
= find_reg_equal_equiv_note (insn
);
3330 if (note
&& REG_NOTE_KIND (note
) == REG_EQUAL
3331 && DF_REG_DEF_COUNT (regno
) != 1)
3334 if (note
!= NULL_RTX
3335 && GET_CODE (XEXP (note
, 0)) != EXPR_LIST
3336 && ! rtx_varies_p (XEXP (note
, 0), 1)
3337 && ! reg_overlap_mentioned_p (SET_DEST (set
),
3340 set_reg_known_value (regno
, XEXP (note
, 0));
3341 set_reg_known_equiv_p (regno
,
3342 REG_NOTE_KIND (note
) == REG_EQUIV
);
3344 else if (DF_REG_DEF_COUNT (regno
) == 1
3345 && GET_CODE (src
) == PLUS
3346 && REG_P (XEXP (src
, 0))
3347 && (t
= get_reg_known_value (REGNO (XEXP (src
, 0))))
3348 && CONST_INT_P (XEXP (src
, 1)))
3350 t
= plus_constant (GET_MODE (src
), t
,
3351 INTVAL (XEXP (src
, 1)));
3352 set_reg_known_value (regno
, t
);
3353 set_reg_known_equiv_p (regno
, false);
3355 else if (DF_REG_DEF_COUNT (regno
) == 1
3356 && ! rtx_varies_p (src
, 1))
3358 set_reg_known_value (regno
, src
);
3359 set_reg_known_equiv_p (regno
, false);
3363 else if (NOTE_P (insn
)
3364 && NOTE_KIND (insn
) == NOTE_INSN_FUNCTION_BEG
)
3365 copying_arguments
= false;
3369 /* Now propagate values from new_reg_base_value to reg_base_value. */
3370 gcc_assert (maxreg
== (unsigned int) max_reg_num ());
3372 for (ui
= 0; ui
< maxreg
; ui
++)
3374 if (new_reg_base_value
[ui
]
3375 && new_reg_base_value
[ui
] != (*reg_base_value
)[ui
]
3376 && ! rtx_equal_p (new_reg_base_value
[ui
], (*reg_base_value
)[ui
]))
3378 (*reg_base_value
)[ui
] = new_reg_base_value
[ui
];
3383 while (changed
&& ++pass
< MAX_ALIAS_LOOP_PASSES
);
3386 /* Fill in the remaining entries. */
3387 FOR_EACH_VEC_ELT (*reg_known_value
, i
, val
)
3389 int regno
= i
+ FIRST_PSEUDO_REGISTER
;
3391 set_reg_known_value (regno
, regno_reg_rtx
[regno
]);
3395 free (new_reg_base_value
);
3396 new_reg_base_value
= 0;
3397 sbitmap_free (reg_seen
);
3399 timevar_pop (TV_ALIAS_ANALYSIS
);
3402 /* Equate REG_BASE_VALUE (reg1) to REG_BASE_VALUE (reg2).
3403 Special API for var-tracking pass purposes. */
3406 vt_equate_reg_base_value (const_rtx reg1
, const_rtx reg2
)
3408 (*reg_base_value
)[REGNO (reg1
)] = REG_BASE_VALUE (reg2
);
3412 end_alias_analysis (void)
3414 old_reg_base_value
= reg_base_value
;
3415 vec_free (reg_known_value
);
3416 sbitmap_free (reg_known_equiv_p
);
3420 dump_alias_stats_in_alias_c (FILE *s
)
3422 fprintf (s
, " TBAA oracle: %llu disambiguations %llu queries\n"
3423 " %llu are in alias set 0\n"
3424 " %llu queries asked about the same object\n"
3425 " %llu queries asked about the same alias set\n"
3426 " %llu access volatile\n"
3427 " %llu are dependent in the DAG\n"
3428 " %llu are aritificially in conflict with void *\n",
3429 alias_stats
.num_disambiguated
,
3430 alias_stats
.num_alias_zero
+ alias_stats
.num_same_alias_set
3431 + alias_stats
.num_same_objects
+ alias_stats
.num_volatile
3432 + alias_stats
.num_dag
+ alias_stats
.num_disambiguated
3433 + alias_stats
.num_universal
,
3434 alias_stats
.num_alias_zero
, alias_stats
.num_same_alias_set
,
3435 alias_stats
.num_same_objects
, alias_stats
.num_volatile
,
3436 alias_stats
.num_dag
, alias_stats
.num_universal
);
3438 #include "gt-alias.h"