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
,
162 static void memory_modified_1 (rtx
, const_rtx
, void *);
164 /* Query statistics for the different low-level disambiguators.
165 A high-level query may trigger multiple of them. */
168 unsigned long long num_alias_zero
;
169 unsigned long long num_same_alias_set
;
170 unsigned long long num_same_objects
;
171 unsigned long long num_volatile
;
172 unsigned long long num_dag
;
173 unsigned long long num_universal
;
174 unsigned long long num_disambiguated
;
178 /* Set up all info needed to perform alias analysis on memory references. */
180 /* Returns the size in bytes of the mode of X. */
181 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
183 /* Cap the number of passes we make over the insns propagating alias
184 information through set chains.
185 ??? 10 is a completely arbitrary choice. This should be based on the
186 maximum loop depth in the CFG, but we do not have this information
187 available (even if current_loops _is_ available). */
188 #define MAX_ALIAS_LOOP_PASSES 10
190 /* reg_base_value[N] gives an address to which register N is related.
191 If all sets after the first add or subtract to the current value
192 or otherwise modify it so it does not point to a different top level
193 object, reg_base_value[N] is equal to the address part of the source
196 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
197 expressions represent three types of base:
199 1. incoming arguments. There is just one ADDRESS to represent all
200 arguments, since we do not know at this level whether accesses
201 based on different arguments can alias. The ADDRESS has id 0.
203 2. stack_pointer_rtx, frame_pointer_rtx, hard_frame_pointer_rtx
204 (if distinct from frame_pointer_rtx) and arg_pointer_rtx.
205 Each of these rtxes has a separate ADDRESS associated with it,
206 each with a negative id.
208 GCC is (and is required to be) precise in which register it
209 chooses to access a particular region of stack. We can therefore
210 assume that accesses based on one of these rtxes do not alias
211 accesses based on another of these rtxes.
213 3. bases that are derived from malloc()ed memory (REG_NOALIAS).
214 Each such piece of memory has a separate ADDRESS associated
215 with it, each with an id greater than 0.
217 Accesses based on one ADDRESS do not alias accesses based on other
218 ADDRESSes. Accesses based on ADDRESSes in groups (2) and (3) do not
219 alias globals either; the ADDRESSes have Pmode to indicate this.
220 The ADDRESS in group (1) _may_ alias globals; it has VOIDmode to
223 static GTY(()) vec
<rtx
, va_gc
> *reg_base_value
;
224 static rtx
*new_reg_base_value
;
226 /* The single VOIDmode ADDRESS that represents all argument bases.
228 static GTY(()) rtx arg_base_value
;
230 /* Used to allocate unique ids to each REG_NOALIAS ADDRESS. */
231 static int unique_id
;
233 /* We preserve the copy of old array around to avoid amount of garbage
234 produced. About 8% of garbage produced were attributed to this
236 static GTY((deletable
)) vec
<rtx
, va_gc
> *old_reg_base_value
;
238 /* Values of XINT (address, 0) of Pmode ADDRESS rtxes for special
240 #define UNIQUE_BASE_VALUE_SP -1
241 #define UNIQUE_BASE_VALUE_ARGP -2
242 #define UNIQUE_BASE_VALUE_FP -3
243 #define UNIQUE_BASE_VALUE_HFP -4
245 #define static_reg_base_value \
246 (this_target_rtl->x_static_reg_base_value)
248 #define REG_BASE_VALUE(X) \
249 (REGNO (X) < vec_safe_length (reg_base_value) \
250 ? (*reg_base_value)[REGNO (X)] : 0)
252 /* Vector indexed by N giving the initial (unchanging) value known for
253 pseudo-register N. This vector is initialized in init_alias_analysis,
254 and does not change until end_alias_analysis is called. */
255 static GTY(()) vec
<rtx
, va_gc
> *reg_known_value
;
257 /* Vector recording for each reg_known_value whether it is due to a
258 REG_EQUIV note. Future passes (viz., reload) may replace the
259 pseudo with the equivalent expression and so we account for the
260 dependences that would be introduced if that happens.
262 The REG_EQUIV notes created in assign_parms may mention the arg
263 pointer, and there are explicit insns in the RTL that modify the
264 arg pointer. Thus we must ensure that such insns don't get
265 scheduled across each other because that would invalidate the
266 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
267 wrong, but solving the problem in the scheduler will likely give
268 better code, so we do it here. */
269 static sbitmap reg_known_equiv_p
;
271 /* True when scanning insns from the start of the rtl to the
272 NOTE_INSN_FUNCTION_BEG note. */
273 static bool copying_arguments
;
276 /* The splay-tree used to store the various alias set entries. */
277 static GTY (()) vec
<alias_set_entry
*, va_gc
> *alias_sets
;
279 /* Build a decomposed reference object for querying the alias-oracle
280 from the MEM rtx and store it in *REF.
281 Returns false if MEM is not suitable for the alias-oracle. */
284 ao_ref_from_mem (ao_ref
*ref
, const_rtx mem
)
286 tree expr
= MEM_EXPR (mem
);
292 ao_ref_init (ref
, expr
);
294 /* Get the base of the reference and see if we have to reject or
296 base
= ao_ref_base (ref
);
297 if (base
== NULL_TREE
)
300 /* The tree oracle doesn't like bases that are neither decls
301 nor indirect references of SSA names. */
303 || (TREE_CODE (base
) == MEM_REF
304 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
305 || (TREE_CODE (base
) == TARGET_MEM_REF
306 && TREE_CODE (TMR_BASE (base
)) == SSA_NAME
)))
309 /* If this is a reference based on a partitioned decl replace the
310 base with a MEM_REF of the pointer representative we
311 created during stack slot partitioning. */
312 if (TREE_CODE (base
) == VAR_DECL
313 && ! is_global_var (base
)
314 && cfun
->gimple_df
->decls_to_pointers
!= NULL
)
316 tree
*namep
= cfun
->gimple_df
->decls_to_pointers
->get (base
);
318 ref
->base
= build_simple_mem_ref (*namep
);
321 ref
->ref_alias_set
= MEM_ALIAS_SET (mem
);
323 /* If MEM_OFFSET or MEM_SIZE are unknown what we got from MEM_EXPR
324 is conservative, so trust it. */
325 if (!MEM_OFFSET_KNOWN_P (mem
)
326 || !MEM_SIZE_KNOWN_P (mem
))
329 /* If MEM_OFFSET/MEM_SIZE get us outside of ref->offset/ref->max_size
331 if (MEM_OFFSET (mem
) < 0
332 || (ref
->max_size
!= -1
333 && ((MEM_OFFSET (mem
) + MEM_SIZE (mem
)) * BITS_PER_UNIT
335 ref
->ref
= NULL_TREE
;
337 /* Refine size and offset we got from analyzing MEM_EXPR by using
338 MEM_SIZE and MEM_OFFSET. */
340 ref
->offset
+= MEM_OFFSET (mem
) * BITS_PER_UNIT
;
341 ref
->size
= MEM_SIZE (mem
) * BITS_PER_UNIT
;
343 /* The MEM may extend into adjacent fields, so adjust max_size if
345 if (ref
->max_size
!= -1
346 && ref
->size
> ref
->max_size
)
347 ref
->max_size
= ref
->size
;
349 /* If MEM_OFFSET and MEM_SIZE get us outside of the base object of
350 the MEM_EXPR punt. This happens for STRICT_ALIGNMENT targets a lot. */
351 if (MEM_EXPR (mem
) != get_spill_slot_decl (false)
353 || (DECL_P (ref
->base
)
354 && (DECL_SIZE (ref
->base
) == NULL_TREE
355 || TREE_CODE (DECL_SIZE (ref
->base
)) != INTEGER_CST
356 || wi::ltu_p (wi::to_offset (DECL_SIZE (ref
->base
)),
357 ref
->offset
+ ref
->size
)))))
363 /* Query the alias-oracle on whether the two memory rtx X and MEM may
364 alias. If TBAA_P is set also apply TBAA. Returns true if the
365 two rtxen may alias, false otherwise. */
368 rtx_refs_may_alias_p (const_rtx x
, const_rtx mem
, bool tbaa_p
)
372 if (!ao_ref_from_mem (&ref1
, x
)
373 || !ao_ref_from_mem (&ref2
, mem
))
376 return refs_may_alias_p_1 (&ref1
, &ref2
,
378 && MEM_ALIAS_SET (x
) != 0
379 && MEM_ALIAS_SET (mem
) != 0);
382 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
383 such an entry, or NULL otherwise. */
385 static inline alias_set_entry
*
386 get_alias_set_entry (alias_set_type alias_set
)
388 return (*alias_sets
)[alias_set
];
391 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
392 the two MEMs cannot alias each other. */
395 mems_in_disjoint_alias_sets_p (const_rtx mem1
, const_rtx mem2
)
397 return (flag_strict_aliasing
398 && ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1
),
399 MEM_ALIAS_SET (mem2
)));
402 /* Return true if the first alias set is a subset of the second. */
405 alias_set_subset_of (alias_set_type set1
, alias_set_type set2
)
407 alias_set_entry
*ase2
;
409 /* Disable TBAA oracle with !flag_strict_aliasing. */
410 if (!flag_strict_aliasing
)
413 /* Everything is a subset of the "aliases everything" set. */
417 /* Check if set1 is a subset of set2. */
418 ase2
= get_alias_set_entry (set2
);
420 && (ase2
->has_zero_child
421 || (ase2
->children
&& ase2
->children
->get (set1
))))
424 /* As a special case we consider alias set of "void *" to be both subset
425 and superset of every alias set of a pointer. This extra symmetry does
426 not matter for alias_sets_conflict_p but it makes aliasing_component_refs_p
427 to return true on the following testcase:
430 char **ptr2=(char **)&ptr;
433 Additionally if a set contains universal pointer, we consider every pointer
434 to be a subset of it, but we do not represent this explicitely - doing so
435 would require us to update transitive closure each time we introduce new
436 pointer type. This makes aliasing_component_refs_p to return true
437 on the following testcase:
439 struct a {void *ptr;}
440 char **ptr = (char **)&a.ptr;
443 This makes void * truly universal pointer type. See pointer handling in
444 get_alias_set for more details. */
445 if (ase2
&& ase2
->has_pointer
)
447 alias_set_entry
*ase1
= get_alias_set_entry (set1
);
449 if (ase1
&& ase1
->is_pointer
)
451 alias_set_type voidptr_set
= TYPE_ALIAS_SET (ptr_type_node
);
452 /* If one is ptr_type_node and other is pointer, then we consider
453 them subset of each other. */
454 if (set1
== voidptr_set
|| set2
== voidptr_set
)
456 /* If SET2 contains universal pointer's alias set, then we consdier
457 every (non-universal) pointer. */
458 if (ase2
->children
&& set1
!= voidptr_set
459 && ase2
->children
->get (voidptr_set
))
466 /* Return 1 if the two specified alias sets may conflict. */
469 alias_sets_conflict_p (alias_set_type set1
, alias_set_type set2
)
471 alias_set_entry
*ase1
;
472 alias_set_entry
*ase2
;
475 if (alias_sets_must_conflict_p (set1
, set2
))
478 /* See if the first alias set is a subset of the second. */
479 ase1
= get_alias_set_entry (set1
);
481 && ase1
->children
&& ase1
->children
->get (set2
))
483 ++alias_stats
.num_dag
;
487 /* Now do the same, but with the alias sets reversed. */
488 ase2
= get_alias_set_entry (set2
);
490 && ase2
->children
&& ase2
->children
->get (set1
))
492 ++alias_stats
.num_dag
;
496 /* We want void * to be compatible with any other pointer without
497 really dropping it to alias set 0. Doing so would make it
498 compatible with all non-pointer types too.
500 This is not strictly necessary by the C/C++ language
501 standards, but avoids common type punning mistakes. In
502 addition to that, we need the existence of such universal
503 pointer to implement Fortran's C_PTR type (which is defined as
504 type compatible with all C pointers). */
505 if (ase1
&& ase2
&& ase1
->has_pointer
&& ase2
->has_pointer
)
507 alias_set_type voidptr_set
= TYPE_ALIAS_SET (ptr_type_node
);
509 /* If one of the sets corresponds to universal pointer,
510 we consider it to conflict with anything that is
511 or contains pointer. */
512 if (set1
== voidptr_set
|| set2
== voidptr_set
)
514 ++alias_stats
.num_universal
;
517 /* If one of sets is (non-universal) pointer and the other
518 contains universal pointer, we also get conflict. */
519 if (ase1
->is_pointer
&& set2
!= voidptr_set
520 && ase2
->children
&& ase2
->children
->get (voidptr_set
))
522 ++alias_stats
.num_universal
;
525 if (ase2
->is_pointer
&& set1
!= voidptr_set
526 && ase1
->children
&& ase1
->children
->get (voidptr_set
))
528 ++alias_stats
.num_universal
;
533 ++alias_stats
.num_disambiguated
;
535 /* The two alias sets are distinct and neither one is the
536 child of the other. Therefore, they cannot conflict. */
540 /* Return 1 if the two specified alias sets will always conflict. */
543 alias_sets_must_conflict_p (alias_set_type set1
, alias_set_type set2
)
545 /* Disable TBAA oracle with !flag_strict_aliasing. */
546 if (!flag_strict_aliasing
)
548 if (set1
== 0 || set2
== 0)
550 ++alias_stats
.num_alias_zero
;
555 ++alias_stats
.num_same_alias_set
;
562 /* Return 1 if any MEM object of type T1 will always conflict (using the
563 dependency routines in this file) with any MEM object of type T2.
564 This is used when allocating temporary storage. If T1 and/or T2 are
565 NULL_TREE, it means we know nothing about the storage. */
568 objects_must_conflict_p (tree t1
, tree t2
)
570 alias_set_type set1
, set2
;
572 /* If neither has a type specified, we don't know if they'll conflict
573 because we may be using them to store objects of various types, for
574 example the argument and local variables areas of inlined functions. */
575 if (t1
== 0 && t2
== 0)
578 /* If they are the same type, they must conflict. */
581 ++alias_stats
.num_same_objects
;
584 /* Likewise if both are volatile. */
585 if (t1
!= 0 && TYPE_VOLATILE (t1
) && t2
!= 0 && TYPE_VOLATILE (t2
))
587 ++alias_stats
.num_volatile
;
591 set1
= t1
? get_alias_set (t1
) : 0;
592 set2
= t2
? get_alias_set (t2
) : 0;
594 /* We can't use alias_sets_conflict_p because we must make sure
595 that every subtype of t1 will conflict with every subtype of
596 t2 for which a pair of subobjects of these respective subtypes
597 overlaps on the stack. */
598 return alias_sets_must_conflict_p (set1
, set2
);
601 /* Return the outermost parent of component present in the chain of
602 component references handled by get_inner_reference in T with the
604 - the component is non-addressable, or
605 - the parent has alias set zero,
606 or NULL_TREE if no such parent exists. In the former cases, the alias
607 set of this parent is the alias set that must be used for T itself. */
610 component_uses_parent_alias_set_from (const_tree t
)
612 const_tree found
= NULL_TREE
;
614 while (handled_component_p (t
))
616 switch (TREE_CODE (t
))
619 if (DECL_NONADDRESSABLE_P (TREE_OPERAND (t
, 1)))
624 case ARRAY_RANGE_REF
:
625 if (TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t
, 0))))
634 case VIEW_CONVERT_EXPR
:
635 /* Bitfields and casts are never addressable. */
643 if (get_alias_set (TREE_TYPE (TREE_OPERAND (t
, 0))) == 0)
646 t
= TREE_OPERAND (t
, 0);
650 return TREE_OPERAND (found
, 0);
656 /* Return whether the pointer-type T effective for aliasing may
657 access everything and thus the reference has to be assigned
661 ref_all_alias_ptr_type_p (const_tree t
)
663 return (TREE_CODE (TREE_TYPE (t
)) == VOID_TYPE
664 || TYPE_REF_CAN_ALIAS_ALL (t
));
667 /* Return the alias set for the memory pointed to by T, which may be
668 either a type or an expression. Return -1 if there is nothing
669 special about dereferencing T. */
671 static alias_set_type
672 get_deref_alias_set_1 (tree t
)
674 /* All we care about is the type. */
678 /* If we have an INDIRECT_REF via a void pointer, we don't
679 know anything about what that might alias. Likewise if the
680 pointer is marked that way. */
681 if (ref_all_alias_ptr_type_p (t
))
687 /* Return the alias set for the memory pointed to by T, which may be
688 either a type or an expression. */
691 get_deref_alias_set (tree t
)
693 /* If we're not doing any alias analysis, just assume everything
694 aliases everything else. */
695 if (!flag_strict_aliasing
)
698 alias_set_type set
= get_deref_alias_set_1 (t
);
700 /* Fall back to the alias-set of the pointed-to type. */
705 set
= get_alias_set (TREE_TYPE (t
));
711 /* Return the pointer-type relevant for TBAA purposes from the
712 memory reference tree *T or NULL_TREE in which case *T is
713 adjusted to point to the outermost component reference that
714 can be used for assigning an alias set. */
717 reference_alias_ptr_type_1 (tree
*t
)
721 /* Get the base object of the reference. */
723 while (handled_component_p (inner
))
725 /* If there is a VIEW_CONVERT_EXPR in the chain we cannot use
726 the type of any component references that wrap it to
727 determine the alias-set. */
728 if (TREE_CODE (inner
) == VIEW_CONVERT_EXPR
)
729 *t
= TREE_OPERAND (inner
, 0);
730 inner
= TREE_OPERAND (inner
, 0);
733 /* Handle pointer dereferences here, they can override the
735 if (INDIRECT_REF_P (inner
)
736 && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner
, 0))))
737 return TREE_TYPE (TREE_OPERAND (inner
, 0));
738 else if (TREE_CODE (inner
) == TARGET_MEM_REF
)
739 return TREE_TYPE (TMR_OFFSET (inner
));
740 else if (TREE_CODE (inner
) == MEM_REF
741 && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner
, 1))))
742 return TREE_TYPE (TREE_OPERAND (inner
, 1));
744 /* If the innermost reference is a MEM_REF that has a
745 conversion embedded treat it like a VIEW_CONVERT_EXPR above,
746 using the memory access type for determining the alias-set. */
747 if (TREE_CODE (inner
) == MEM_REF
748 && (TYPE_MAIN_VARIANT (TREE_TYPE (inner
))
750 (TREE_TYPE (TREE_TYPE (TREE_OPERAND (inner
, 1))))))
751 return TREE_TYPE (TREE_OPERAND (inner
, 1));
753 /* Otherwise, pick up the outermost object that we could have
755 tree tem
= component_uses_parent_alias_set_from (*t
);
762 /* Return the pointer-type relevant for TBAA purposes from the
763 gimple memory reference tree T. This is the type to be used for
764 the offset operand of MEM_REF or TARGET_MEM_REF replacements of T
765 and guarantees that get_alias_set will return the same alias
766 set for T and the replacement. */
769 reference_alias_ptr_type (tree t
)
771 tree ptype
= reference_alias_ptr_type_1 (&t
);
772 /* If there is a given pointer type for aliasing purposes, return it. */
773 if (ptype
!= NULL_TREE
)
776 /* Otherwise build one from the outermost component reference we
778 if (TREE_CODE (t
) == MEM_REF
779 || TREE_CODE (t
) == TARGET_MEM_REF
)
780 return TREE_TYPE (TREE_OPERAND (t
, 1));
782 return build_pointer_type (TYPE_MAIN_VARIANT (TREE_TYPE (t
)));
785 /* Return whether the pointer-types T1 and T2 used to determine
786 two alias sets of two references will yield the same answer
787 from get_deref_alias_set. */
790 alias_ptr_types_compatible_p (tree t1
, tree t2
)
792 if (TYPE_MAIN_VARIANT (t1
) == TYPE_MAIN_VARIANT (t2
))
795 if (ref_all_alias_ptr_type_p (t1
)
796 || ref_all_alias_ptr_type_p (t2
))
799 return (TYPE_MAIN_VARIANT (TREE_TYPE (t1
))
800 == TYPE_MAIN_VARIANT (TREE_TYPE (t2
)));
803 /* Create emptry alias set entry. */
806 init_alias_set_entry (alias_set_type set
)
808 alias_set_entry
*ase
= ggc_alloc
<alias_set_entry
> ();
809 ase
->alias_set
= set
;
810 ase
->children
= NULL
;
811 ase
->has_zero_child
= false;
812 ase
->is_pointer
= false;
813 ase
->has_pointer
= false;
814 gcc_checking_assert (!get_alias_set_entry (set
));
815 (*alias_sets
)[set
] = ase
;
819 /* Return the alias set for T, which may be either a type or an
820 expression. Call language-specific routine for help, if needed. */
823 get_alias_set (tree t
)
827 /* We can not give up with -fno-strict-aliasing because we need to build
828 proper type representation for possible functions which are build with
829 -fstirct-aliasing. */
831 /* return 0 if this or its type is an error. */
832 if (t
== error_mark_node
834 && (TREE_TYPE (t
) == 0 || TREE_TYPE (t
) == error_mark_node
)))
837 /* We can be passed either an expression or a type. This and the
838 language-specific routine may make mutually-recursive calls to each other
839 to figure out what to do. At each juncture, we see if this is a tree
840 that the language may need to handle specially. First handle things that
844 /* Give the language a chance to do something with this tree
845 before we look at it. */
847 set
= lang_hooks
.get_alias_set (t
);
851 /* Get the alias pointer-type to use or the outermost object
852 that we could have a pointer to. */
853 tree ptype
= reference_alias_ptr_type_1 (&t
);
855 return get_deref_alias_set (ptype
);
857 /* If we've already determined the alias set for a decl, just return
858 it. This is necessary for C++ anonymous unions, whose component
859 variables don't look like union members (boo!). */
860 if (TREE_CODE (t
) == VAR_DECL
861 && DECL_RTL_SET_P (t
) && MEM_P (DECL_RTL (t
)))
862 return MEM_ALIAS_SET (DECL_RTL (t
));
864 /* Now all we care about is the type. */
868 /* Variant qualifiers don't affect the alias set, so get the main
870 t
= TYPE_MAIN_VARIANT (t
);
872 /* Always use the canonical type as well. If this is a type that
873 requires structural comparisons to identify compatible types
874 use alias set zero. */
875 if (TYPE_STRUCTURAL_EQUALITY_P (t
))
877 /* Allow the language to specify another alias set for this
879 set
= lang_hooks
.get_alias_set (t
);
882 /* Handle structure type equality for pointer types, arrays and vectors.
883 This is easy to do, because the code bellow ignore canonical types on
884 these anyway. This is important for LTO, where TYPE_CANONICAL for
885 pointers can not be meaningfuly computed by the frotnend. */
886 if (canonical_type_used_p (t
))
888 /* In LTO we set canonical types for all types where it makes
889 sense to do so. Double check we did not miss some type. */
890 gcc_checking_assert (!in_lto_p
|| !type_with_alias_set_p (t
));
896 t
= TYPE_CANONICAL (t
);
897 gcc_checking_assert (!TYPE_STRUCTURAL_EQUALITY_P (t
));
900 /* If this is a type with a known alias set, return it. */
901 gcc_checking_assert (t
== TYPE_MAIN_VARIANT (t
));
902 if (TYPE_ALIAS_SET_KNOWN_P (t
))
903 return TYPE_ALIAS_SET (t
);
905 /* We don't want to set TYPE_ALIAS_SET for incomplete types. */
906 if (!COMPLETE_TYPE_P (t
))
908 /* For arrays with unknown size the conservative answer is the
909 alias set of the element type. */
910 if (TREE_CODE (t
) == ARRAY_TYPE
)
911 return get_alias_set (TREE_TYPE (t
));
913 /* But return zero as a conservative answer for incomplete types. */
917 /* See if the language has special handling for this type. */
918 set
= lang_hooks
.get_alias_set (t
);
922 /* There are no objects of FUNCTION_TYPE, so there's no point in
923 using up an alias set for them. (There are, of course, pointers
924 and references to functions, but that's different.) */
925 else if (TREE_CODE (t
) == FUNCTION_TYPE
|| TREE_CODE (t
) == METHOD_TYPE
)
928 /* Unless the language specifies otherwise, let vector types alias
929 their components. This avoids some nasty type punning issues in
930 normal usage. And indeed lets vectors be treated more like an
932 else if (TREE_CODE (t
) == VECTOR_TYPE
)
933 set
= get_alias_set (TREE_TYPE (t
));
935 /* Unless the language specifies otherwise, treat array types the
936 same as their components. This avoids the asymmetry we get
937 through recording the components. Consider accessing a
938 character(kind=1) through a reference to a character(kind=1)[1:1].
939 Or consider if we want to assign integer(kind=4)[0:D.1387] and
940 integer(kind=4)[4] the same alias set or not.
941 Just be pragmatic here and make sure the array and its element
942 type get the same alias set assigned. */
943 else if (TREE_CODE (t
) == ARRAY_TYPE
944 && (!TYPE_NONALIASED_COMPONENT (t
)
945 || TYPE_STRUCTURAL_EQUALITY_P (t
)))
946 set
= get_alias_set (TREE_TYPE (t
));
948 /* From the former common C and C++ langhook implementation:
950 Unfortunately, there is no canonical form of a pointer type.
951 In particular, if we have `typedef int I', then `int *', and
952 `I *' are different types. So, we have to pick a canonical
953 representative. We do this below.
955 Technically, this approach is actually more conservative that
956 it needs to be. In particular, `const int *' and `int *'
957 should be in different alias sets, according to the C and C++
958 standard, since their types are not the same, and so,
959 technically, an `int **' and `const int **' cannot point at
962 But, the standard is wrong. In particular, this code is
967 const int* const* cipp = ipp;
968 And, it doesn't make sense for that to be legal unless you
969 can dereference IPP and CIPP. So, we ignore cv-qualifiers on
970 the pointed-to types. This issue has been reported to the
973 For this reason go to canonical type of the unqalified pointer type.
974 Until GCC 6 this code set all pointers sets to have alias set of
975 ptr_type_node but that is a bad idea, because it prevents disabiguations
976 in between pointers. For Firefox this accounts about 20% of all
977 disambiguations in the program. */
978 else if (POINTER_TYPE_P (t
) && t
!= ptr_type_node
)
981 auto_vec
<bool, 8> reference
;
983 /* Unnest all pointers and references.
984 We also want to make pointer to array/vector equivalent to pointer to
985 its element (see the reasoning above). Skip all those types, too. */
986 for (p
= t
; POINTER_TYPE_P (p
)
987 || (TREE_CODE (p
) == ARRAY_TYPE
988 && (!TYPE_NONALIASED_COMPONENT (p
)
989 || !COMPLETE_TYPE_P (p
)
990 || TYPE_STRUCTURAL_EQUALITY_P (p
)))
991 || TREE_CODE (p
) == VECTOR_TYPE
;
994 /* Ada supports recusive pointers. Instead of doing recrusion check
995 just give up once the preallocated space of 8 elements is up.
996 In this case just punt to void * alias set. */
997 if (reference
.length () == 8)
1002 if (TREE_CODE (p
) == REFERENCE_TYPE
)
1003 /* In LTO we want languages that use references to be compatible
1004 with languages that use pointers. */
1005 reference
.safe_push (true && !in_lto_p
);
1006 if (TREE_CODE (p
) == POINTER_TYPE
)
1007 reference
.safe_push (false);
1009 p
= TYPE_MAIN_VARIANT (p
);
1011 /* Make void * compatible with char * and also void **.
1012 Programs are commonly violating TBAA by this.
1014 We also make void * to conflict with every pointer
1015 (see record_component_aliases) and thus it is safe it to use it for
1016 pointers to types with TYPE_STRUCTURAL_EQUALITY_P. */
1017 if (TREE_CODE (p
) == VOID_TYPE
|| TYPE_STRUCTURAL_EQUALITY_P (p
))
1018 set
= get_alias_set (ptr_type_node
);
1021 /* Rebuild pointer type starting from canonical types using
1022 unqualified pointers and references only. This way all such
1023 pointers will have the same alias set and will conflict with
1026 Most of time we already have pointers or references of a given type.
1027 If not we build new one just to be sure that if someone later
1028 (probably only middle-end can, as we should assign all alias
1029 classes only after finishing translation unit) builds the pointer
1030 type, the canonical type will match. */
1031 p
= TYPE_CANONICAL (p
);
1032 while (!reference
.is_empty ())
1034 if (reference
.pop ())
1035 p
= build_reference_type (p
);
1037 p
= build_pointer_type (p
);
1038 gcc_checking_assert (p
== TYPE_MAIN_VARIANT (p
));
1039 /* build_pointer_type should always return the canonical type.
1040 For LTO TYPE_CANOINCAL may be NULL, because we do not compute
1041 them. Be sure that frontends do not glob canonical types of
1042 pointers in unexpected way and that p == TYPE_CANONICAL (p)
1043 in all other cases. */
1044 gcc_checking_assert (!TYPE_CANONICAL (p
)
1045 || p
== TYPE_CANONICAL (p
));
1048 /* Assign the alias set to both p and t.
1049 We can not call get_alias_set (p) here as that would trigger
1050 infinite recursion when p == t. In other cases it would just
1051 trigger unnecesary legwork of rebuilding the pointer again. */
1052 gcc_checking_assert (p
== TYPE_MAIN_VARIANT (p
));
1053 if (TYPE_ALIAS_SET_KNOWN_P (p
))
1054 set
= TYPE_ALIAS_SET (p
);
1057 set
= new_alias_set ();
1058 TYPE_ALIAS_SET (p
) = set
;
1062 /* Alias set of ptr_type_node is special and serve as universal pointer which
1063 is TBAA compatible with every other pointer type. Be sure we have the
1064 alias set built even for LTO which otherwise keeps all TYPE_CANONICAL
1065 of pointer types NULL. */
1066 else if (t
== ptr_type_node
)
1067 set
= new_alias_set ();
1069 /* Otherwise make a new alias set for this type. */
1072 /* Each canonical type gets its own alias set, so canonical types
1073 shouldn't form a tree. It doesn't really matter for types
1074 we handle specially above, so only check it where it possibly
1075 would result in a bogus alias set. */
1076 gcc_checking_assert (TYPE_CANONICAL (t
) == t
);
1078 set
= new_alias_set ();
1081 TYPE_ALIAS_SET (t
) = set
;
1083 /* If this is an aggregate type or a complex type, we must record any
1084 component aliasing information. */
1085 if (AGGREGATE_TYPE_P (t
) || TREE_CODE (t
) == COMPLEX_TYPE
)
1086 record_component_aliases (t
);
1088 /* We treat pointer types specially in alias_set_subset_of. */
1089 if (POINTER_TYPE_P (t
) && set
)
1091 alias_set_entry
*ase
= get_alias_set_entry (set
);
1093 ase
= init_alias_set_entry (set
);
1094 ase
->is_pointer
= true;
1095 ase
->has_pointer
= true;
1101 /* Return a brand-new alias set. */
1104 new_alias_set (void)
1106 if (alias_sets
== 0)
1107 vec_safe_push (alias_sets
, (alias_set_entry
*) NULL
);
1108 vec_safe_push (alias_sets
, (alias_set_entry
*) NULL
);
1109 return alias_sets
->length () - 1;
1112 /* Indicate that things in SUBSET can alias things in SUPERSET, but that
1113 not everything that aliases SUPERSET also aliases SUBSET. For example,
1114 in C, a store to an `int' can alias a load of a structure containing an
1115 `int', and vice versa. But it can't alias a load of a 'double' member
1116 of the same structure. Here, the structure would be the SUPERSET and
1117 `int' the SUBSET. This relationship is also described in the comment at
1118 the beginning of this file.
1120 This function should be called only once per SUPERSET/SUBSET pair.
1122 It is illegal for SUPERSET to be zero; everything is implicitly a
1123 subset of alias set zero. */
1126 record_alias_subset (alias_set_type superset
, alias_set_type subset
)
1128 alias_set_entry
*superset_entry
;
1129 alias_set_entry
*subset_entry
;
1131 /* It is possible in complex type situations for both sets to be the same,
1132 in which case we can ignore this operation. */
1133 if (superset
== subset
)
1136 gcc_assert (superset
);
1138 superset_entry
= get_alias_set_entry (superset
);
1139 if (superset_entry
== 0)
1141 /* Create an entry for the SUPERSET, so that we have a place to
1142 attach the SUBSET. */
1143 superset_entry
= init_alias_set_entry (superset
);
1147 superset_entry
->has_zero_child
= 1;
1150 subset_entry
= get_alias_set_entry (subset
);
1151 if (!superset_entry
->children
)
1152 superset_entry
->children
1153 = hash_map
<alias_set_hash
, int>::create_ggc (64);
1154 /* If there is an entry for the subset, enter all of its children
1155 (if they are not already present) as children of the SUPERSET. */
1158 if (subset_entry
->has_zero_child
)
1159 superset_entry
->has_zero_child
= true;
1160 if (subset_entry
->has_pointer
)
1161 superset_entry
->has_pointer
= true;
1163 if (subset_entry
->children
)
1165 hash_map
<alias_set_hash
, int>::iterator iter
1166 = subset_entry
->children
->begin ();
1167 for (; iter
!= subset_entry
->children
->end (); ++iter
)
1168 superset_entry
->children
->put ((*iter
).first
, (*iter
).second
);
1172 /* Enter the SUBSET itself as a child of the SUPERSET. */
1173 superset_entry
->children
->put (subset
, 0);
1177 /* Record that component types of TYPE, if any, are part of that type for
1178 aliasing purposes. For record types, we only record component types
1179 for fields that are not marked non-addressable. For array types, we
1180 only record the component type if it is not marked non-aliased. */
1183 record_component_aliases (tree type
)
1185 alias_set_type superset
= get_alias_set (type
);
1191 switch (TREE_CODE (type
))
1195 case QUAL_UNION_TYPE
:
1196 for (field
= TYPE_FIELDS (type
); field
!= 0; field
= DECL_CHAIN (field
))
1197 if (TREE_CODE (field
) == FIELD_DECL
&& !DECL_NONADDRESSABLE_P (field
))
1199 /* LTO type merging does not make any difference between
1200 component pointer types. We may have
1202 struct foo {int *a;};
1204 as TYPE_CANONICAL of
1206 struct bar {float *a;};
1208 Because accesses to int * and float * do not alias, we would get
1209 false negative when accessing the same memory location by
1210 float ** and bar *. We thus record the canonical type as:
1214 void * is special cased and works as a universal pointer type.
1215 Accesses to it conflicts with accesses to any other pointer
1217 tree t
= TREE_TYPE (field
);
1220 /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their
1221 element type and that type has to be normalized to void *,
1222 too, in the case it is a pointer. */
1223 while (!canonical_type_used_p (t
) && !POINTER_TYPE_P (t
))
1225 gcc_checking_assert (TYPE_STRUCTURAL_EQUALITY_P (t
));
1228 if (POINTER_TYPE_P (t
))
1230 else if (flag_checking
)
1231 gcc_checking_assert (get_alias_set (t
)
1232 == get_alias_set (TREE_TYPE (field
)));
1235 record_alias_subset (superset
, get_alias_set (t
));
1240 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
1243 /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their
1251 /* Allocate an alias set for use in storing and reading from the varargs
1254 static GTY(()) alias_set_type varargs_set
= -1;
1257 get_varargs_alias_set (void)
1260 /* We now lower VA_ARG_EXPR, and there's currently no way to attach the
1261 varargs alias set to an INDIRECT_REF (FIXME!), so we can't
1262 consistently use the varargs alias set for loads from the varargs
1263 area. So don't use it anywhere. */
1266 if (varargs_set
== -1)
1267 varargs_set
= new_alias_set ();
1273 /* Likewise, but used for the fixed portions of the frame, e.g., register
1276 static GTY(()) alias_set_type frame_set
= -1;
1279 get_frame_alias_set (void)
1281 if (frame_set
== -1)
1282 frame_set
= new_alias_set ();
1287 /* Create a new, unique base with id ID. */
1290 unique_base_value (HOST_WIDE_INT id
)
1292 return gen_rtx_ADDRESS (Pmode
, id
);
1295 /* Return true if accesses based on any other base value cannot alias
1296 those based on X. */
1299 unique_base_value_p (rtx x
)
1301 return GET_CODE (x
) == ADDRESS
&& GET_MODE (x
) == Pmode
;
1304 /* Return true if X is known to be a base value. */
1307 known_base_value_p (rtx x
)
1309 switch (GET_CODE (x
))
1316 /* Arguments may or may not be bases; we don't know for sure. */
1317 return GET_MODE (x
) != VOIDmode
;
1324 /* Inside SRC, the source of a SET, find a base address. */
1327 find_base_value (rtx src
)
1331 #if defined (FIND_BASE_TERM)
1332 /* Try machine-dependent ways to find the base term. */
1333 src
= FIND_BASE_TERM (src
);
1336 switch (GET_CODE (src
))
1343 regno
= REGNO (src
);
1344 /* At the start of a function, argument registers have known base
1345 values which may be lost later. Returning an ADDRESS
1346 expression here allows optimization based on argument values
1347 even when the argument registers are used for other purposes. */
1348 if (regno
< FIRST_PSEUDO_REGISTER
&& copying_arguments
)
1349 return new_reg_base_value
[regno
];
1351 /* If a pseudo has a known base value, return it. Do not do this
1352 for non-fixed hard regs since it can result in a circular
1353 dependency chain for registers which have values at function entry.
1355 The test above is not sufficient because the scheduler may move
1356 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
1357 if ((regno
>= FIRST_PSEUDO_REGISTER
|| fixed_regs
[regno
])
1358 && regno
< vec_safe_length (reg_base_value
))
1360 /* If we're inside init_alias_analysis, use new_reg_base_value
1361 to reduce the number of relaxation iterations. */
1362 if (new_reg_base_value
&& new_reg_base_value
[regno
]
1363 && DF_REG_DEF_COUNT (regno
) == 1)
1364 return new_reg_base_value
[regno
];
1366 if ((*reg_base_value
)[regno
])
1367 return (*reg_base_value
)[regno
];
1373 /* Check for an argument passed in memory. Only record in the
1374 copying-arguments block; it is too hard to track changes
1376 if (copying_arguments
1377 && (XEXP (src
, 0) == arg_pointer_rtx
1378 || (GET_CODE (XEXP (src
, 0)) == PLUS
1379 && XEXP (XEXP (src
, 0), 0) == arg_pointer_rtx
)))
1380 return arg_base_value
;
1384 src
= XEXP (src
, 0);
1385 if (GET_CODE (src
) != PLUS
&& GET_CODE (src
) != MINUS
)
1388 /* ... fall through ... */
1393 rtx temp
, src_0
= XEXP (src
, 0), src_1
= XEXP (src
, 1);
1395 /* If either operand is a REG that is a known pointer, then it
1397 if (REG_P (src_0
) && REG_POINTER (src_0
))
1398 return find_base_value (src_0
);
1399 if (REG_P (src_1
) && REG_POINTER (src_1
))
1400 return find_base_value (src_1
);
1402 /* If either operand is a REG, then see if we already have
1403 a known value for it. */
1406 temp
= find_base_value (src_0
);
1413 temp
= find_base_value (src_1
);
1418 /* If either base is named object or a special address
1419 (like an argument or stack reference), then use it for the
1421 if (src_0
!= 0 && known_base_value_p (src_0
))
1424 if (src_1
!= 0 && known_base_value_p (src_1
))
1427 /* Guess which operand is the base address:
1428 If either operand is a symbol, then it is the base. If
1429 either operand is a CONST_INT, then the other is the base. */
1430 if (CONST_INT_P (src_1
) || CONSTANT_P (src_0
))
1431 return find_base_value (src_0
);
1432 else if (CONST_INT_P (src_0
) || CONSTANT_P (src_1
))
1433 return find_base_value (src_1
);
1439 /* The standard form is (lo_sum reg sym) so look only at the
1441 return find_base_value (XEXP (src
, 1));
1444 /* If the second operand is constant set the base
1445 address to the first operand. */
1446 if (CONST_INT_P (XEXP (src
, 1)) && INTVAL (XEXP (src
, 1)) != 0)
1447 return find_base_value (XEXP (src
, 0));
1451 /* As we do not know which address space the pointer is referring to, we can
1452 handle this only if the target does not support different pointer or
1453 address modes depending on the address space. */
1454 if (!target_default_pointer_address_modes_p ())
1456 if (GET_MODE_SIZE (GET_MODE (src
)) < GET_MODE_SIZE (Pmode
))
1466 return find_base_value (XEXP (src
, 0));
1469 case SIGN_EXTEND
: /* used for NT/Alpha pointers */
1470 /* As we do not know which address space the pointer is referring to, we can
1471 handle this only if the target does not support different pointer or
1472 address modes depending on the address space. */
1473 if (!target_default_pointer_address_modes_p ())
1477 rtx temp
= find_base_value (XEXP (src
, 0));
1479 if (temp
!= 0 && CONSTANT_P (temp
))
1480 temp
= convert_memory_address (Pmode
, temp
);
1492 /* Called from init_alias_analysis indirectly through note_stores,
1493 or directly if DEST is a register with a REG_NOALIAS note attached.
1494 SET is null in the latter case. */
1496 /* While scanning insns to find base values, reg_seen[N] is nonzero if
1497 register N has been set in this function. */
1498 static sbitmap reg_seen
;
1501 record_set (rtx dest
, const_rtx set
, void *data ATTRIBUTE_UNUSED
)
1510 regno
= REGNO (dest
);
1512 gcc_checking_assert (regno
< reg_base_value
->length ());
1514 n
= REG_NREGS (dest
);
1519 bitmap_set_bit (reg_seen
, regno
+ n
);
1520 new_reg_base_value
[regno
+ n
] = 0;
1527 /* A CLOBBER wipes out any old value but does not prevent a previously
1528 unset register from acquiring a base address (i.e. reg_seen is not
1530 if (GET_CODE (set
) == CLOBBER
)
1532 new_reg_base_value
[regno
] = 0;
1535 src
= SET_SRC (set
);
1539 /* There's a REG_NOALIAS note against DEST. */
1540 if (bitmap_bit_p (reg_seen
, regno
))
1542 new_reg_base_value
[regno
] = 0;
1545 bitmap_set_bit (reg_seen
, regno
);
1546 new_reg_base_value
[regno
] = unique_base_value (unique_id
++);
1550 /* If this is not the first set of REGNO, see whether the new value
1551 is related to the old one. There are two cases of interest:
1553 (1) The register might be assigned an entirely new value
1554 that has the same base term as the original set.
1556 (2) The set might be a simple self-modification that
1557 cannot change REGNO's base value.
1559 If neither case holds, reject the original base value as invalid.
1560 Note that the following situation is not detected:
1562 extern int x, y; int *p = &x; p += (&y-&x);
1564 ANSI C does not allow computing the difference of addresses
1565 of distinct top level objects. */
1566 if (new_reg_base_value
[regno
] != 0
1567 && find_base_value (src
) != new_reg_base_value
[regno
])
1568 switch (GET_CODE (src
))
1572 if (XEXP (src
, 0) != dest
&& XEXP (src
, 1) != dest
)
1573 new_reg_base_value
[regno
] = 0;
1576 /* If the value we add in the PLUS is also a valid base value,
1577 this might be the actual base value, and the original value
1580 rtx other
= NULL_RTX
;
1582 if (XEXP (src
, 0) == dest
)
1583 other
= XEXP (src
, 1);
1584 else if (XEXP (src
, 1) == dest
)
1585 other
= XEXP (src
, 0);
1587 if (! other
|| find_base_value (other
))
1588 new_reg_base_value
[regno
] = 0;
1592 if (XEXP (src
, 0) != dest
|| !CONST_INT_P (XEXP (src
, 1)))
1593 new_reg_base_value
[regno
] = 0;
1596 new_reg_base_value
[regno
] = 0;
1599 /* If this is the first set of a register, record the value. */
1600 else if ((regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
1601 && ! bitmap_bit_p (reg_seen
, regno
) && new_reg_base_value
[regno
] == 0)
1602 new_reg_base_value
[regno
] = find_base_value (src
);
1604 bitmap_set_bit (reg_seen
, regno
);
1607 /* Return REG_BASE_VALUE for REGNO. Selective scheduler uses this to avoid
1608 using hard registers with non-null REG_BASE_VALUE for renaming. */
1610 get_reg_base_value (unsigned int regno
)
1612 return (*reg_base_value
)[regno
];
1615 /* If a value is known for REGNO, return it. */
1618 get_reg_known_value (unsigned int regno
)
1620 if (regno
>= FIRST_PSEUDO_REGISTER
)
1622 regno
-= FIRST_PSEUDO_REGISTER
;
1623 if (regno
< vec_safe_length (reg_known_value
))
1624 return (*reg_known_value
)[regno
];
1632 set_reg_known_value (unsigned int regno
, rtx val
)
1634 if (regno
>= FIRST_PSEUDO_REGISTER
)
1636 regno
-= FIRST_PSEUDO_REGISTER
;
1637 if (regno
< vec_safe_length (reg_known_value
))
1638 (*reg_known_value
)[regno
] = val
;
1642 /* Similarly for reg_known_equiv_p. */
1645 get_reg_known_equiv_p (unsigned int regno
)
1647 if (regno
>= FIRST_PSEUDO_REGISTER
)
1649 regno
-= FIRST_PSEUDO_REGISTER
;
1650 if (regno
< vec_safe_length (reg_known_value
))
1651 return bitmap_bit_p (reg_known_equiv_p
, regno
);
1657 set_reg_known_equiv_p (unsigned int regno
, bool val
)
1659 if (regno
>= FIRST_PSEUDO_REGISTER
)
1661 regno
-= FIRST_PSEUDO_REGISTER
;
1662 if (regno
< vec_safe_length (reg_known_value
))
1665 bitmap_set_bit (reg_known_equiv_p
, regno
);
1667 bitmap_clear_bit (reg_known_equiv_p
, regno
);
1673 /* Returns a canonical version of X, from the point of view alias
1674 analysis. (For example, if X is a MEM whose address is a register,
1675 and the register has a known value (say a SYMBOL_REF), then a MEM
1676 whose address is the SYMBOL_REF is returned.) */
1681 /* Recursively look for equivalences. */
1682 if (REG_P (x
) && REGNO (x
) >= FIRST_PSEUDO_REGISTER
)
1684 rtx t
= get_reg_known_value (REGNO (x
));
1688 return canon_rtx (t
);
1691 if (GET_CODE (x
) == PLUS
)
1693 rtx x0
= canon_rtx (XEXP (x
, 0));
1694 rtx x1
= canon_rtx (XEXP (x
, 1));
1696 if (x0
!= XEXP (x
, 0) || x1
!= XEXP (x
, 1))
1698 if (CONST_INT_P (x0
))
1699 return plus_constant (GET_MODE (x
), x1
, INTVAL (x0
));
1700 else if (CONST_INT_P (x1
))
1701 return plus_constant (GET_MODE (x
), x0
, INTVAL (x1
));
1702 return gen_rtx_PLUS (GET_MODE (x
), x0
, x1
);
1706 /* This gives us much better alias analysis when called from
1707 the loop optimizer. Note we want to leave the original
1708 MEM alone, but need to return the canonicalized MEM with
1709 all the flags with their original values. */
1711 x
= replace_equiv_address_nv (x
, canon_rtx (XEXP (x
, 0)));
1716 /* Return 1 if X and Y are identical-looking rtx's.
1717 Expect that X and Y has been already canonicalized.
1719 We use the data in reg_known_value above to see if two registers with
1720 different numbers are, in fact, equivalent. */
1723 rtx_equal_for_memref_p (const_rtx x
, const_rtx y
)
1730 if (x
== 0 && y
== 0)
1732 if (x
== 0 || y
== 0)
1738 code
= GET_CODE (x
);
1739 /* Rtx's of different codes cannot be equal. */
1740 if (code
!= GET_CODE (y
))
1743 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1744 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1746 if (GET_MODE (x
) != GET_MODE (y
))
1749 /* Some RTL can be compared without a recursive examination. */
1753 return REGNO (x
) == REGNO (y
);
1756 return LABEL_REF_LABEL (x
) == LABEL_REF_LABEL (y
);
1760 tree x_decl
= SYMBOL_REF_DECL (x
);
1761 tree y_decl
= SYMBOL_REF_DECL (y
);
1763 if (!x_decl
|| !y_decl
)
1764 return XSTR (x
, 0) == XSTR (y
, 0);
1766 return compare_base_decls (x_decl
, y_decl
) == 1;
1770 /* This is magic, don't go through canonicalization et al. */
1771 return rtx_equal_p (ENTRY_VALUE_EXP (x
), ENTRY_VALUE_EXP (y
));
1775 /* Pointer equality guarantees equality for these nodes. */
1782 /* canon_rtx knows how to handle plus. No need to canonicalize. */
1784 return ((rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0))
1785 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 1)))
1786 || (rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 1))
1787 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 0))));
1788 /* For commutative operations, the RTX match if the operand match in any
1789 order. Also handle the simple binary and unary cases without a loop. */
1790 if (COMMUTATIVE_P (x
))
1792 rtx xop0
= canon_rtx (XEXP (x
, 0));
1793 rtx yop0
= canon_rtx (XEXP (y
, 0));
1794 rtx yop1
= canon_rtx (XEXP (y
, 1));
1796 return ((rtx_equal_for_memref_p (xop0
, yop0
)
1797 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop1
))
1798 || (rtx_equal_for_memref_p (xop0
, yop1
)
1799 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop0
)));
1801 else if (NON_COMMUTATIVE_P (x
))
1803 return (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1804 canon_rtx (XEXP (y
, 0)))
1805 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)),
1806 canon_rtx (XEXP (y
, 1))));
1808 else if (UNARY_P (x
))
1809 return rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1810 canon_rtx (XEXP (y
, 0)));
1812 /* Compare the elements. If any pair of corresponding elements
1813 fail to match, return 0 for the whole things.
1815 Limit cases to types which actually appear in addresses. */
1817 fmt
= GET_RTX_FORMAT (code
);
1818 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1823 if (XINT (x
, i
) != XINT (y
, i
))
1828 /* Two vectors must have the same length. */
1829 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1832 /* And the corresponding elements must match. */
1833 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1834 if (rtx_equal_for_memref_p (canon_rtx (XVECEXP (x
, i
, j
)),
1835 canon_rtx (XVECEXP (y
, i
, j
))) == 0)
1840 if (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, i
)),
1841 canon_rtx (XEXP (y
, i
))) == 0)
1845 /* This can happen for asm operands. */
1847 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1851 /* This can happen for an asm which clobbers memory. */
1855 /* It is believed that rtx's at this level will never
1856 contain anything but integers and other rtx's,
1857 except for within LABEL_REFs and SYMBOL_REFs. */
1866 find_base_term (rtx x
)
1869 struct elt_loc_list
*l
, *f
;
1872 #if defined (FIND_BASE_TERM)
1873 /* Try machine-dependent ways to find the base term. */
1874 x
= FIND_BASE_TERM (x
);
1877 switch (GET_CODE (x
))
1880 return REG_BASE_VALUE (x
);
1883 /* As we do not know which address space the pointer is referring to, we can
1884 handle this only if the target does not support different pointer or
1885 address modes depending on the address space. */
1886 if (!target_default_pointer_address_modes_p ())
1888 if (GET_MODE_SIZE (GET_MODE (x
)) < GET_MODE_SIZE (Pmode
))
1898 return find_base_term (XEXP (x
, 0));
1901 case SIGN_EXTEND
: /* Used for Alpha/NT pointers */
1902 /* As we do not know which address space the pointer is referring to, we can
1903 handle this only if the target does not support different pointer or
1904 address modes depending on the address space. */
1905 if (!target_default_pointer_address_modes_p ())
1909 rtx temp
= find_base_term (XEXP (x
, 0));
1911 if (temp
!= 0 && CONSTANT_P (temp
))
1912 temp
= convert_memory_address (Pmode
, temp
);
1918 val
= CSELIB_VAL_PTR (x
);
1924 if (cselib_sp_based_value_p (val
))
1925 return static_reg_base_value
[STACK_POINTER_REGNUM
];
1928 /* Temporarily reset val->locs to avoid infinite recursion. */
1931 for (l
= f
; l
; l
= l
->next
)
1932 if (GET_CODE (l
->loc
) == VALUE
1933 && CSELIB_VAL_PTR (l
->loc
)->locs
1934 && !CSELIB_VAL_PTR (l
->loc
)->locs
->next
1935 && CSELIB_VAL_PTR (l
->loc
)->locs
->loc
== x
)
1937 else if ((ret
= find_base_term (l
->loc
)) != 0)
1944 /* The standard form is (lo_sum reg sym) so look only at the
1946 return find_base_term (XEXP (x
, 1));
1950 if (GET_CODE (x
) != PLUS
&& GET_CODE (x
) != MINUS
)
1956 rtx tmp1
= XEXP (x
, 0);
1957 rtx tmp2
= XEXP (x
, 1);
1959 /* This is a little bit tricky since we have to determine which of
1960 the two operands represents the real base address. Otherwise this
1961 routine may return the index register instead of the base register.
1963 That may cause us to believe no aliasing was possible, when in
1964 fact aliasing is possible.
1966 We use a few simple tests to guess the base register. Additional
1967 tests can certainly be added. For example, if one of the operands
1968 is a shift or multiply, then it must be the index register and the
1969 other operand is the base register. */
1971 if (tmp1
== pic_offset_table_rtx
&& CONSTANT_P (tmp2
))
1972 return find_base_term (tmp2
);
1974 /* If either operand is known to be a pointer, then prefer it
1975 to determine the base term. */
1976 if (REG_P (tmp1
) && REG_POINTER (tmp1
))
1978 else if (REG_P (tmp2
) && REG_POINTER (tmp2
))
1979 std::swap (tmp1
, tmp2
);
1980 /* If second argument is constant which has base term, prefer it
1981 over variable tmp1. See PR64025. */
1982 else if (CONSTANT_P (tmp2
) && !CONST_INT_P (tmp2
))
1983 std::swap (tmp1
, tmp2
);
1985 /* Go ahead and find the base term for both operands. If either base
1986 term is from a pointer or is a named object or a special address
1987 (like an argument or stack reference), then use it for the
1989 rtx base
= find_base_term (tmp1
);
1990 if (base
!= NULL_RTX
1991 && ((REG_P (tmp1
) && REG_POINTER (tmp1
))
1992 || known_base_value_p (base
)))
1994 base
= find_base_term (tmp2
);
1995 if (base
!= NULL_RTX
1996 && ((REG_P (tmp2
) && REG_POINTER (tmp2
))
1997 || known_base_value_p (base
)))
2000 /* We could not determine which of the two operands was the
2001 base register and which was the index. So we can determine
2002 nothing from the base alias check. */
2007 if (CONST_INT_P (XEXP (x
, 1)) && INTVAL (XEXP (x
, 1)) != 0)
2008 return find_base_term (XEXP (x
, 0));
2020 /* Return true if accesses to address X may alias accesses based
2021 on the stack pointer. */
2024 may_be_sp_based_p (rtx x
)
2026 rtx base
= find_base_term (x
);
2027 return !base
|| base
== static_reg_base_value
[STACK_POINTER_REGNUM
];
2030 /* BASE1 and BASE2 are decls. Return 1 if they refer to same object, 0
2031 if they refer to different objects and -1 if we can not decide. */
2034 compare_base_decls (tree base1
, tree base2
)
2037 gcc_checking_assert (DECL_P (base1
) && DECL_P (base2
));
2041 /* Declarations of non-automatic variables may have aliases. All other
2042 decls are unique. */
2043 if (!decl_in_symtab_p (base1
)
2044 || !decl_in_symtab_p (base2
))
2047 /* Don't cause symbols to be inserted by the act of checking. */
2048 symtab_node
*node1
= symtab_node::get (base1
);
2051 symtab_node
*node2
= symtab_node::get (base2
);
2055 ret
= node1
->equal_address_to (node2
, true);
2059 /* Return 0 if the addresses X and Y are known to point to different
2060 objects, 1 if they might be pointers to the same object. */
2063 base_alias_check (rtx x
, rtx x_base
, rtx y
, rtx y_base
,
2064 machine_mode x_mode
, machine_mode y_mode
)
2066 /* If the address itself has no known base see if a known equivalent
2067 value has one. If either address still has no known base, nothing
2068 is known about aliasing. */
2073 if (! flag_expensive_optimizations
|| (x_c
= canon_rtx (x
)) == x
)
2076 x_base
= find_base_term (x_c
);
2084 if (! flag_expensive_optimizations
|| (y_c
= canon_rtx (y
)) == y
)
2087 y_base
= find_base_term (y_c
);
2092 /* If the base addresses are equal nothing is known about aliasing. */
2093 if (rtx_equal_p (x_base
, y_base
))
2096 /* The base addresses are different expressions. If they are not accessed
2097 via AND, there is no conflict. We can bring knowledge of object
2098 alignment into play here. For example, on alpha, "char a, b;" can
2099 alias one another, though "char a; long b;" cannot. AND addesses may
2100 implicitly alias surrounding objects; i.e. unaligned access in DImode
2101 via AND address can alias all surrounding object types except those
2102 with aligment 8 or higher. */
2103 if (GET_CODE (x
) == AND
&& GET_CODE (y
) == AND
)
2105 if (GET_CODE (x
) == AND
2106 && (!CONST_INT_P (XEXP (x
, 1))
2107 || (int) GET_MODE_UNIT_SIZE (y_mode
) < -INTVAL (XEXP (x
, 1))))
2109 if (GET_CODE (y
) == AND
2110 && (!CONST_INT_P (XEXP (y
, 1))
2111 || (int) GET_MODE_UNIT_SIZE (x_mode
) < -INTVAL (XEXP (y
, 1))))
2114 if (GET_CODE (x_base
) == SYMBOL_REF
&& GET_CODE (y_base
) == SYMBOL_REF
)
2116 tree x_decl
= SYMBOL_REF_DECL (x_base
);
2117 tree y_decl
= SYMBOL_REF_DECL (y_base
);
2119 /* We can assume that no stores are made to labels. */
2120 if (!x_decl
|| !y_decl
)
2122 return compare_base_decls (x_decl
, y_decl
) != 0;
2125 /* Differing symbols not accessed via AND never alias. */
2126 if (GET_CODE (x_base
) != ADDRESS
&& GET_CODE (y_base
) != ADDRESS
)
2129 if (unique_base_value_p (x_base
) || unique_base_value_p (y_base
))
2135 /* Return TRUE if EXPR refers to a VALUE whose uid is greater than
2136 (or equal to) that of V. */
2139 refs_newer_value_p (const_rtx expr
, rtx v
)
2141 int minuid
= CSELIB_VAL_PTR (v
)->uid
;
2142 subrtx_iterator::array_type array
;
2143 FOR_EACH_SUBRTX (iter
, array
, expr
, NONCONST
)
2144 if (GET_CODE (*iter
) == VALUE
&& CSELIB_VAL_PTR (*iter
)->uid
>= minuid
)
2149 /* Convert the address X into something we can use. This is done by returning
2150 it unchanged unless it is a value; in the latter case we call cselib to get
2151 a more useful rtx. */
2157 struct elt_loc_list
*l
;
2159 if (GET_CODE (x
) != VALUE
)
2161 v
= CSELIB_VAL_PTR (x
);
2164 bool have_equivs
= cselib_have_permanent_equivalences ();
2166 v
= canonical_cselib_val (v
);
2167 for (l
= v
->locs
; l
; l
= l
->next
)
2168 if (CONSTANT_P (l
->loc
))
2170 for (l
= v
->locs
; l
; l
= l
->next
)
2171 if (!REG_P (l
->loc
) && !MEM_P (l
->loc
)
2172 /* Avoid infinite recursion when potentially dealing with
2173 var-tracking artificial equivalences, by skipping the
2174 equivalences themselves, and not choosing expressions
2175 that refer to newer VALUEs. */
2177 || (GET_CODE (l
->loc
) != VALUE
2178 && !refs_newer_value_p (l
->loc
, x
))))
2182 for (l
= v
->locs
; l
; l
= l
->next
)
2184 || (GET_CODE (l
->loc
) != VALUE
2185 && !refs_newer_value_p (l
->loc
, x
)))
2187 /* Return the canonical value. */
2191 return v
->locs
->loc
;
2196 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
2197 where SIZE is the size in bytes of the memory reference. If ADDR
2198 is not modified by the memory reference then ADDR is returned. */
2201 addr_side_effect_eval (rtx addr
, int size
, int n_refs
)
2205 switch (GET_CODE (addr
))
2208 offset
= (n_refs
+ 1) * size
;
2211 offset
= -(n_refs
+ 1) * size
;
2214 offset
= n_refs
* size
;
2217 offset
= -n_refs
* size
;
2225 addr
= gen_rtx_PLUS (GET_MODE (addr
), XEXP (addr
, 0),
2226 gen_int_mode (offset
, GET_MODE (addr
)));
2228 addr
= XEXP (addr
, 0);
2229 addr
= canon_rtx (addr
);
2234 /* Return TRUE if an object X sized at XSIZE bytes and another object
2235 Y sized at YSIZE bytes, starting C bytes after X, may overlap. If
2236 any of the sizes is zero, assume an overlap, otherwise use the
2237 absolute value of the sizes as the actual sizes. */
2240 offset_overlap_p (HOST_WIDE_INT c
, int xsize
, int ysize
)
2242 return (xsize
== 0 || ysize
== 0
2245 : (abs (ysize
) > -c
)));
2248 /* Return one if X and Y (memory addresses) reference the
2249 same location in memory or if the references overlap.
2250 Return zero if they do not overlap, else return
2251 minus one in which case they still might reference the same location.
2253 C is an offset accumulator. When
2254 C is nonzero, we are testing aliases between X and Y + C.
2255 XSIZE is the size in bytes of the X reference,
2256 similarly YSIZE is the size in bytes for Y.
2257 Expect that canon_rtx has been already called for X and Y.
2259 If XSIZE or YSIZE is zero, we do not know the amount of memory being
2260 referenced (the reference was BLKmode), so make the most pessimistic
2263 If XSIZE or YSIZE is negative, we may access memory outside the object
2264 being referenced as a side effect. This can happen when using AND to
2265 align memory references, as is done on the Alpha.
2267 Nice to notice that varying addresses cannot conflict with fp if no
2268 local variables had their addresses taken, but that's too hard now.
2270 ??? Contrary to the tree alias oracle this does not return
2271 one for X + non-constant and Y + non-constant when X and Y are equal.
2272 If that is fixed the TBAA hack for union type-punning can be removed. */
2275 memrefs_conflict_p (int xsize
, rtx x
, int ysize
, rtx y
, HOST_WIDE_INT c
)
2277 if (GET_CODE (x
) == VALUE
)
2281 struct elt_loc_list
*l
= NULL
;
2282 if (CSELIB_VAL_PTR (x
))
2283 for (l
= canonical_cselib_val (CSELIB_VAL_PTR (x
))->locs
;
2285 if (REG_P (l
->loc
) && rtx_equal_for_memref_p (l
->loc
, y
))
2292 /* Don't call get_addr if y is the same VALUE. */
2296 if (GET_CODE (y
) == VALUE
)
2300 struct elt_loc_list
*l
= NULL
;
2301 if (CSELIB_VAL_PTR (y
))
2302 for (l
= canonical_cselib_val (CSELIB_VAL_PTR (y
))->locs
;
2304 if (REG_P (l
->loc
) && rtx_equal_for_memref_p (l
->loc
, x
))
2311 /* Don't call get_addr if x is the same VALUE. */
2315 if (GET_CODE (x
) == HIGH
)
2317 else if (GET_CODE (x
) == LO_SUM
)
2320 x
= addr_side_effect_eval (x
, abs (xsize
), 0);
2321 if (GET_CODE (y
) == HIGH
)
2323 else if (GET_CODE (y
) == LO_SUM
)
2326 y
= addr_side_effect_eval (y
, abs (ysize
), 0);
2328 if (GET_CODE (x
) == SYMBOL_REF
&& GET_CODE (y
) == SYMBOL_REF
)
2330 tree x_decl
= SYMBOL_REF_DECL (x
);
2331 tree y_decl
= SYMBOL_REF_DECL (y
);
2334 if (!x_decl
|| !y_decl
)
2336 /* Label and normal symbol are never the same. */
2337 if (x_decl
!= y_decl
)
2339 return offset_overlap_p (c
, xsize
, ysize
);
2342 cmp
= compare_base_decls (x_decl
, y_decl
);
2344 /* If both decls are the same, decide by offsets. */
2346 return offset_overlap_p (c
, xsize
, ysize
);
2347 /* Assume a potential overlap for symbolic addresses that went
2348 through alignment adjustments (i.e., that have negative
2349 sizes), because we can't know how far they are from each
2351 if (xsize
< 0 || ysize
< 0)
2353 /* If decls are different or we know by offsets that there is no overlap,
2355 if (!cmp
|| !offset_overlap_p (c
, xsize
, ysize
))
2357 /* Decls may or may not be different and offsets overlap....*/
2360 else if (rtx_equal_for_memref_p (x
, y
))
2362 return offset_overlap_p (c
, xsize
, ysize
);
2365 /* This code used to check for conflicts involving stack references and
2366 globals but the base address alias code now handles these cases. */
2368 if (GET_CODE (x
) == PLUS
)
2370 /* The fact that X is canonicalized means that this
2371 PLUS rtx is canonicalized. */
2372 rtx x0
= XEXP (x
, 0);
2373 rtx x1
= XEXP (x
, 1);
2375 /* However, VALUEs might end up in different positions even in
2376 canonical PLUSes. Comparing their addresses is enough. */
2378 return memrefs_conflict_p (xsize
, x1
, ysize
, const0_rtx
, c
);
2380 return memrefs_conflict_p (xsize
, x0
, ysize
, const0_rtx
, c
);
2382 if (GET_CODE (y
) == PLUS
)
2384 /* The fact that Y is canonicalized means that this
2385 PLUS rtx is canonicalized. */
2386 rtx y0
= XEXP (y
, 0);
2387 rtx y1
= XEXP (y
, 1);
2390 return memrefs_conflict_p (xsize
, x1
, ysize
, y0
, c
);
2392 return memrefs_conflict_p (xsize
, x0
, ysize
, y1
, c
);
2394 if (rtx_equal_for_memref_p (x1
, y1
))
2395 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
2396 if (rtx_equal_for_memref_p (x0
, y0
))
2397 return memrefs_conflict_p (xsize
, x1
, ysize
, y1
, c
);
2398 if (CONST_INT_P (x1
))
2400 if (CONST_INT_P (y1
))
2401 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
,
2402 c
- INTVAL (x1
) + INTVAL (y1
));
2404 return memrefs_conflict_p (xsize
, x0
, ysize
, y
,
2407 else if (CONST_INT_P (y1
))
2408 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
2412 else if (CONST_INT_P (x1
))
2413 return memrefs_conflict_p (xsize
, x0
, ysize
, y
, c
- INTVAL (x1
));
2415 else if (GET_CODE (y
) == PLUS
)
2417 /* The fact that Y is canonicalized means that this
2418 PLUS rtx is canonicalized. */
2419 rtx y0
= XEXP (y
, 0);
2420 rtx y1
= XEXP (y
, 1);
2423 return memrefs_conflict_p (xsize
, const0_rtx
, ysize
, y1
, c
);
2425 return memrefs_conflict_p (xsize
, const0_rtx
, ysize
, y0
, c
);
2427 if (CONST_INT_P (y1
))
2428 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
2433 if (GET_CODE (x
) == GET_CODE (y
))
2434 switch (GET_CODE (x
))
2438 /* Handle cases where we expect the second operands to be the
2439 same, and check only whether the first operand would conflict
2442 rtx x1
= canon_rtx (XEXP (x
, 1));
2443 rtx y1
= canon_rtx (XEXP (y
, 1));
2444 if (! rtx_equal_for_memref_p (x1
, y1
))
2446 x0
= canon_rtx (XEXP (x
, 0));
2447 y0
= canon_rtx (XEXP (y
, 0));
2448 if (rtx_equal_for_memref_p (x0
, y0
))
2449 return offset_overlap_p (c
, xsize
, ysize
);
2451 /* Can't properly adjust our sizes. */
2452 if (!CONST_INT_P (x1
))
2454 xsize
/= INTVAL (x1
);
2455 ysize
/= INTVAL (x1
);
2457 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
2464 /* Deal with alignment ANDs by adjusting offset and size so as to
2465 cover the maximum range, without taking any previously known
2466 alignment into account. Make a size negative after such an
2467 adjustments, so that, if we end up with e.g. two SYMBOL_REFs, we
2468 assume a potential overlap, because they may end up in contiguous
2469 memory locations and the stricter-alignment access may span over
2471 if (GET_CODE (x
) == AND
&& CONST_INT_P (XEXP (x
, 1)))
2473 HOST_WIDE_INT sc
= INTVAL (XEXP (x
, 1));
2474 unsigned HOST_WIDE_INT uc
= sc
;
2475 if (sc
< 0 && -uc
== (uc
& -uc
))
2482 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2486 if (GET_CODE (y
) == AND
&& CONST_INT_P (XEXP (y
, 1)))
2488 HOST_WIDE_INT sc
= INTVAL (XEXP (y
, 1));
2489 unsigned HOST_WIDE_INT uc
= sc
;
2490 if (sc
< 0 && -uc
== (uc
& -uc
))
2497 return memrefs_conflict_p (xsize
, x
,
2498 ysize
, canon_rtx (XEXP (y
, 0)), c
);
2504 if (CONST_INT_P (x
) && CONST_INT_P (y
))
2506 c
+= (INTVAL (y
) - INTVAL (x
));
2507 return offset_overlap_p (c
, xsize
, ysize
);
2510 if (GET_CODE (x
) == CONST
)
2512 if (GET_CODE (y
) == CONST
)
2513 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2514 ysize
, canon_rtx (XEXP (y
, 0)), c
);
2516 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2519 if (GET_CODE (y
) == CONST
)
2520 return memrefs_conflict_p (xsize
, x
, ysize
,
2521 canon_rtx (XEXP (y
, 0)), c
);
2523 /* Assume a potential overlap for symbolic addresses that went
2524 through alignment adjustments (i.e., that have negative
2525 sizes), because we can't know how far they are from each
2528 return (xsize
< 0 || ysize
< 0 || offset_overlap_p (c
, xsize
, ysize
));
2536 /* Functions to compute memory dependencies.
2538 Since we process the insns in execution order, we can build tables
2539 to keep track of what registers are fixed (and not aliased), what registers
2540 are varying in known ways, and what registers are varying in unknown
2543 If both memory references are volatile, then there must always be a
2544 dependence between the two references, since their order can not be
2545 changed. A volatile and non-volatile reference can be interchanged
2548 We also must allow AND addresses, because they may generate accesses
2549 outside the object being referenced. This is used to generate aligned
2550 addresses from unaligned addresses, for instance, the alpha
2551 storeqi_unaligned pattern. */
2553 /* Read dependence: X is read after read in MEM takes place. There can
2554 only be a dependence here if both reads are volatile, or if either is
2555 an explicit barrier. */
2558 read_dependence (const_rtx mem
, const_rtx x
)
2560 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2562 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2563 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2568 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
2571 decl_for_component_ref (tree x
)
2575 x
= TREE_OPERAND (x
, 0);
2577 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
2579 return x
&& DECL_P (x
) ? x
: NULL_TREE
;
2582 /* Walk up the COMPONENT_REF list in X and adjust *OFFSET to compensate
2583 for the offset of the field reference. *KNOWN_P says whether the
2587 adjust_offset_for_component_ref (tree x
, bool *known_p
,
2588 HOST_WIDE_INT
*offset
)
2594 tree xoffset
= component_ref_field_offset (x
);
2595 tree field
= TREE_OPERAND (x
, 1);
2596 if (TREE_CODE (xoffset
) != INTEGER_CST
)
2603 = (wi::to_offset (xoffset
)
2604 + wi::lrshift (wi::to_offset (DECL_FIELD_BIT_OFFSET (field
)),
2605 LOG2_BITS_PER_UNIT
));
2606 if (!wi::fits_uhwi_p (woffset
))
2611 *offset
+= woffset
.to_uhwi ();
2613 x
= TREE_OPERAND (x
, 0);
2615 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
2618 /* Return nonzero if we can determine the exprs corresponding to memrefs
2619 X and Y and they do not overlap.
2620 If LOOP_VARIANT is set, skip offset-based disambiguation */
2623 nonoverlapping_memrefs_p (const_rtx x
, const_rtx y
, bool loop_invariant
)
2625 tree exprx
= MEM_EXPR (x
), expry
= MEM_EXPR (y
);
2628 bool moffsetx_known_p
, moffsety_known_p
;
2629 HOST_WIDE_INT moffsetx
= 0, moffsety
= 0;
2630 HOST_WIDE_INT offsetx
= 0, offsety
= 0, sizex
, sizey
;
2632 /* Unless both have exprs, we can't tell anything. */
2633 if (exprx
== 0 || expry
== 0)
2636 /* For spill-slot accesses make sure we have valid offsets. */
2637 if ((exprx
== get_spill_slot_decl (false)
2638 && ! MEM_OFFSET_KNOWN_P (x
))
2639 || (expry
== get_spill_slot_decl (false)
2640 && ! MEM_OFFSET_KNOWN_P (y
)))
2643 /* If the field reference test failed, look at the DECLs involved. */
2644 moffsetx_known_p
= MEM_OFFSET_KNOWN_P (x
);
2645 if (moffsetx_known_p
)
2646 moffsetx
= MEM_OFFSET (x
);
2647 if (TREE_CODE (exprx
) == COMPONENT_REF
)
2649 tree t
= decl_for_component_ref (exprx
);
2652 adjust_offset_for_component_ref (exprx
, &moffsetx_known_p
, &moffsetx
);
2656 moffsety_known_p
= MEM_OFFSET_KNOWN_P (y
);
2657 if (moffsety_known_p
)
2658 moffsety
= MEM_OFFSET (y
);
2659 if (TREE_CODE (expry
) == COMPONENT_REF
)
2661 tree t
= decl_for_component_ref (expry
);
2664 adjust_offset_for_component_ref (expry
, &moffsety_known_p
, &moffsety
);
2668 if (! DECL_P (exprx
) || ! DECL_P (expry
))
2671 /* If we refer to different gimple registers, or one gimple register
2672 and one non-gimple-register, we know they can't overlap. First,
2673 gimple registers don't have their addresses taken. Now, there
2674 could be more than one stack slot for (different versions of) the
2675 same gimple register, but we can presumably tell they don't
2676 overlap based on offsets from stack base addresses elsewhere.
2677 It's important that we don't proceed to DECL_RTL, because gimple
2678 registers may not pass DECL_RTL_SET_P, and make_decl_rtl won't be
2679 able to do anything about them since no SSA information will have
2680 remained to guide it. */
2681 if (is_gimple_reg (exprx
) || is_gimple_reg (expry
))
2682 return exprx
!= expry
2683 || (moffsetx_known_p
&& moffsety_known_p
2684 && MEM_SIZE_KNOWN_P (x
) && MEM_SIZE_KNOWN_P (y
)
2685 && !offset_overlap_p (moffsety
- moffsetx
,
2686 MEM_SIZE (x
), MEM_SIZE (y
)));
2688 /* With invalid code we can end up storing into the constant pool.
2689 Bail out to avoid ICEing when creating RTL for this.
2690 See gfortran.dg/lto/20091028-2_0.f90. */
2691 if (TREE_CODE (exprx
) == CONST_DECL
2692 || TREE_CODE (expry
) == CONST_DECL
)
2695 rtlx
= DECL_RTL (exprx
);
2696 rtly
= DECL_RTL (expry
);
2698 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
2699 can't overlap unless they are the same because we never reuse that part
2700 of the stack frame used for locals for spilled pseudos. */
2701 if ((!MEM_P (rtlx
) || !MEM_P (rtly
))
2702 && ! rtx_equal_p (rtlx
, rtly
))
2705 /* If we have MEMs referring to different address spaces (which can
2706 potentially overlap), we cannot easily tell from the addresses
2707 whether the references overlap. */
2708 if (MEM_P (rtlx
) && MEM_P (rtly
)
2709 && MEM_ADDR_SPACE (rtlx
) != MEM_ADDR_SPACE (rtly
))
2712 /* Get the base and offsets of both decls. If either is a register, we
2713 know both are and are the same, so use that as the base. The only
2714 we can avoid overlap is if we can deduce that they are nonoverlapping
2715 pieces of that decl, which is very rare. */
2716 basex
= MEM_P (rtlx
) ? XEXP (rtlx
, 0) : rtlx
;
2717 if (GET_CODE (basex
) == PLUS
&& CONST_INT_P (XEXP (basex
, 1)))
2718 offsetx
= INTVAL (XEXP (basex
, 1)), basex
= XEXP (basex
, 0);
2720 basey
= MEM_P (rtly
) ? XEXP (rtly
, 0) : rtly
;
2721 if (GET_CODE (basey
) == PLUS
&& CONST_INT_P (XEXP (basey
, 1)))
2722 offsety
= INTVAL (XEXP (basey
, 1)), basey
= XEXP (basey
, 0);
2724 /* If the bases are different, we know they do not overlap if both
2725 are constants or if one is a constant and the other a pointer into the
2726 stack frame. Otherwise a different base means we can't tell if they
2728 if (compare_base_decls (exprx
, expry
) == 0)
2729 return ((CONSTANT_P (basex
) && CONSTANT_P (basey
))
2730 || (CONSTANT_P (basex
) && REG_P (basey
)
2731 && REGNO_PTR_FRAME_P (REGNO (basey
)))
2732 || (CONSTANT_P (basey
) && REG_P (basex
)
2733 && REGNO_PTR_FRAME_P (REGNO (basex
))));
2735 /* Offset based disambiguation not appropriate for loop invariant */
2739 /* Offset based disambiguation is OK even if we do not know that the
2740 declarations are necessarily different
2741 (i.e. compare_base_decls (exprx, expry) == -1) */
2743 sizex
= (!MEM_P (rtlx
) ? (int) GET_MODE_SIZE (GET_MODE (rtlx
))
2744 : MEM_SIZE_KNOWN_P (rtlx
) ? MEM_SIZE (rtlx
)
2746 sizey
= (!MEM_P (rtly
) ? (int) GET_MODE_SIZE (GET_MODE (rtly
))
2747 : MEM_SIZE_KNOWN_P (rtly
) ? MEM_SIZE (rtly
)
2750 /* If we have an offset for either memref, it can update the values computed
2752 if (moffsetx_known_p
)
2753 offsetx
+= moffsetx
, sizex
-= moffsetx
;
2754 if (moffsety_known_p
)
2755 offsety
+= moffsety
, sizey
-= moffsety
;
2757 /* If a memref has both a size and an offset, we can use the smaller size.
2758 We can't do this if the offset isn't known because we must view this
2759 memref as being anywhere inside the DECL's MEM. */
2760 if (MEM_SIZE_KNOWN_P (x
) && moffsetx_known_p
)
2761 sizex
= MEM_SIZE (x
);
2762 if (MEM_SIZE_KNOWN_P (y
) && moffsety_known_p
)
2763 sizey
= MEM_SIZE (y
);
2765 /* Put the values of the memref with the lower offset in X's values. */
2766 if (offsetx
> offsety
)
2768 std::swap (offsetx
, offsety
);
2769 std::swap (sizex
, sizey
);
2772 /* If we don't know the size of the lower-offset value, we can't tell
2773 if they conflict. Otherwise, we do the test. */
2774 return sizex
>= 0 && offsety
>= offsetx
+ sizex
;
2777 /* Helper for true_dependence and canon_true_dependence.
2778 Checks for true dependence: X is read after store in MEM takes place.
2780 If MEM_CANONICALIZED is FALSE, then X_ADDR and MEM_ADDR should be
2781 NULL_RTX, and the canonical addresses of MEM and X are both computed
2782 here. If MEM_CANONICALIZED, then MEM must be already canonicalized.
2784 If X_ADDR is non-NULL, it is used in preference of XEXP (x, 0).
2786 Returns 1 if there is a true dependence, 0 otherwise. */
2789 true_dependence_1 (const_rtx mem
, machine_mode mem_mode
, rtx mem_addr
,
2790 const_rtx x
, rtx x_addr
, bool mem_canonicalized
)
2796 gcc_checking_assert (mem_canonicalized
? (mem_addr
!= NULL_RTX
)
2797 : (mem_addr
== NULL_RTX
&& x_addr
== NULL_RTX
));
2799 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2802 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2803 This is used in epilogue deallocation functions, and in cselib. */
2804 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2806 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2808 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2809 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2813 x_addr
= XEXP (x
, 0);
2814 x_addr
= get_addr (x_addr
);
2818 mem_addr
= XEXP (mem
, 0);
2819 if (mem_mode
== VOIDmode
)
2820 mem_mode
= GET_MODE (mem
);
2822 true_mem_addr
= get_addr (mem_addr
);
2824 /* Read-only memory is by definition never modified, and therefore can't
2825 conflict with anything. However, don't assume anything when AND
2826 addresses are involved and leave to the code below to determine
2827 dependence. We don't expect to find read-only set on MEM, but
2828 stupid user tricks can produce them, so don't die. */
2829 if (MEM_READONLY_P (x
)
2830 && GET_CODE (x_addr
) != AND
2831 && GET_CODE (true_mem_addr
) != AND
)
2834 /* If we have MEMs referring to different address spaces (which can
2835 potentially overlap), we cannot easily tell from the addresses
2836 whether the references overlap. */
2837 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
2840 base
= find_base_term (x_addr
);
2841 if (base
&& (GET_CODE (base
) == LABEL_REF
2842 || (GET_CODE (base
) == SYMBOL_REF
2843 && CONSTANT_POOL_ADDRESS_P (base
))))
2846 rtx mem_base
= find_base_term (true_mem_addr
);
2847 if (! base_alias_check (x_addr
, base
, true_mem_addr
, mem_base
,
2848 GET_MODE (x
), mem_mode
))
2851 x_addr
= canon_rtx (x_addr
);
2852 if (!mem_canonicalized
)
2853 mem_addr
= canon_rtx (true_mem_addr
);
2855 if ((ret
= memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
2856 SIZE_FOR_MODE (x
), x_addr
, 0)) != -1)
2859 if (mems_in_disjoint_alias_sets_p (x
, mem
))
2862 if (nonoverlapping_memrefs_p (mem
, x
, false))
2865 return rtx_refs_may_alias_p (x
, mem
, true);
2868 /* True dependence: X is read after store in MEM takes place. */
2871 true_dependence (const_rtx mem
, machine_mode mem_mode
, const_rtx x
)
2873 return true_dependence_1 (mem
, mem_mode
, NULL_RTX
,
2874 x
, NULL_RTX
, /*mem_canonicalized=*/false);
2877 /* Canonical true dependence: X is read after store in MEM takes place.
2878 Variant of true_dependence which assumes MEM has already been
2879 canonicalized (hence we no longer do that here).
2880 The mem_addr argument has been added, since true_dependence_1 computed
2881 this value prior to canonicalizing. */
2884 canon_true_dependence (const_rtx mem
, machine_mode mem_mode
, rtx mem_addr
,
2885 const_rtx x
, rtx x_addr
)
2887 return true_dependence_1 (mem
, mem_mode
, mem_addr
,
2888 x
, x_addr
, /*mem_canonicalized=*/true);
2891 /* Returns nonzero if a write to X might alias a previous read from
2892 (or, if WRITEP is true, a write to) MEM.
2893 If X_CANONCALIZED is true, then X_ADDR is the canonicalized address of X,
2894 and X_MODE the mode for that access.
2895 If MEM_CANONICALIZED is true, MEM is canonicalized. */
2898 write_dependence_p (const_rtx mem
,
2899 const_rtx x
, machine_mode x_mode
, rtx x_addr
,
2900 bool mem_canonicalized
, bool x_canonicalized
, bool writep
)
2903 rtx true_mem_addr
, true_x_addr
;
2907 gcc_checking_assert (x_canonicalized
2908 ? (x_addr
!= NULL_RTX
&& x_mode
!= VOIDmode
)
2909 : (x_addr
== NULL_RTX
&& x_mode
== VOIDmode
));
2911 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2914 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2915 This is used in epilogue deallocation functions. */
2916 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2918 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2920 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2921 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2925 x_addr
= XEXP (x
, 0);
2926 true_x_addr
= get_addr (x_addr
);
2928 mem_addr
= XEXP (mem
, 0);
2929 true_mem_addr
= get_addr (mem_addr
);
2931 /* A read from read-only memory can't conflict with read-write memory.
2932 Don't assume anything when AND addresses are involved and leave to
2933 the code below to determine dependence. */
2935 && MEM_READONLY_P (mem
)
2936 && GET_CODE (true_x_addr
) != AND
2937 && GET_CODE (true_mem_addr
) != AND
)
2940 /* If we have MEMs referring to different address spaces (which can
2941 potentially overlap), we cannot easily tell from the addresses
2942 whether the references overlap. */
2943 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
2946 base
= find_base_term (true_mem_addr
);
2949 && (GET_CODE (base
) == LABEL_REF
2950 || (GET_CODE (base
) == SYMBOL_REF
2951 && CONSTANT_POOL_ADDRESS_P (base
))))
2954 rtx x_base
= find_base_term (true_x_addr
);
2955 if (! base_alias_check (true_x_addr
, x_base
, true_mem_addr
, base
,
2956 GET_MODE (x
), GET_MODE (mem
)))
2959 if (!x_canonicalized
)
2961 x_addr
= canon_rtx (true_x_addr
);
2962 x_mode
= GET_MODE (x
);
2964 if (!mem_canonicalized
)
2965 mem_addr
= canon_rtx (true_mem_addr
);
2967 if ((ret
= memrefs_conflict_p (SIZE_FOR_MODE (mem
), mem_addr
,
2968 GET_MODE_SIZE (x_mode
), x_addr
, 0)) != -1)
2971 if (nonoverlapping_memrefs_p (x
, mem
, false))
2974 return rtx_refs_may_alias_p (x
, mem
, false);
2977 /* Anti dependence: X is written after read in MEM takes place. */
2980 anti_dependence (const_rtx mem
, const_rtx x
)
2982 return write_dependence_p (mem
, x
, VOIDmode
, NULL_RTX
,
2983 /*mem_canonicalized=*/false,
2984 /*x_canonicalized*/false, /*writep=*/false);
2987 /* Likewise, but we already have a canonicalized MEM, and X_ADDR for X.
2988 Also, consider X in X_MODE (which might be from an enclosing
2989 STRICT_LOW_PART / ZERO_EXTRACT).
2990 If MEM_CANONICALIZED is true, MEM is canonicalized. */
2993 canon_anti_dependence (const_rtx mem
, bool mem_canonicalized
,
2994 const_rtx x
, machine_mode x_mode
, rtx x_addr
)
2996 return write_dependence_p (mem
, x
, x_mode
, x_addr
,
2997 mem_canonicalized
, /*x_canonicalized=*/true,
3001 /* Output dependence: X is written after store in MEM takes place. */
3004 output_dependence (const_rtx mem
, const_rtx x
)
3006 return write_dependence_p (mem
, x
, VOIDmode
, NULL_RTX
,
3007 /*mem_canonicalized=*/false,
3008 /*x_canonicalized*/false, /*writep=*/true);
3013 /* Check whether X may be aliased with MEM. Don't do offset-based
3014 memory disambiguation & TBAA. */
3016 may_alias_p (const_rtx mem
, const_rtx x
)
3018 rtx x_addr
, mem_addr
;
3020 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
3023 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
3024 This is used in epilogue deallocation functions. */
3025 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
3027 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
3029 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
3030 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
3033 x_addr
= XEXP (x
, 0);
3034 x_addr
= get_addr (x_addr
);
3036 mem_addr
= XEXP (mem
, 0);
3037 mem_addr
= get_addr (mem_addr
);
3039 /* Read-only memory is by definition never modified, and therefore can't
3040 conflict with anything. However, don't assume anything when AND
3041 addresses are involved and leave to the code below to determine
3042 dependence. We don't expect to find read-only set on MEM, but
3043 stupid user tricks can produce them, so don't die. */
3044 if (MEM_READONLY_P (x
)
3045 && GET_CODE (x_addr
) != AND
3046 && GET_CODE (mem_addr
) != AND
)
3049 /* If we have MEMs referring to different address spaces (which can
3050 potentially overlap), we cannot easily tell from the addresses
3051 whether the references overlap. */
3052 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
3055 rtx x_base
= find_base_term (x_addr
);
3056 rtx mem_base
= find_base_term (mem_addr
);
3057 if (! base_alias_check (x_addr
, x_base
, mem_addr
, mem_base
,
3058 GET_MODE (x
), GET_MODE (mem_addr
)))
3061 if (nonoverlapping_memrefs_p (mem
, x
, true))
3064 /* TBAA not valid for loop_invarint */
3065 return rtx_refs_may_alias_p (x
, mem
, false);
3069 init_alias_target (void)
3073 if (!arg_base_value
)
3074 arg_base_value
= gen_rtx_ADDRESS (VOIDmode
, 0);
3076 memset (static_reg_base_value
, 0, sizeof static_reg_base_value
);
3078 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3079 /* Check whether this register can hold an incoming pointer
3080 argument. FUNCTION_ARG_REGNO_P tests outgoing register
3081 numbers, so translate if necessary due to register windows. */
3082 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i
))
3083 && HARD_REGNO_MODE_OK (i
, Pmode
))
3084 static_reg_base_value
[i
] = arg_base_value
;
3086 static_reg_base_value
[STACK_POINTER_REGNUM
]
3087 = unique_base_value (UNIQUE_BASE_VALUE_SP
);
3088 static_reg_base_value
[ARG_POINTER_REGNUM
]
3089 = unique_base_value (UNIQUE_BASE_VALUE_ARGP
);
3090 static_reg_base_value
[FRAME_POINTER_REGNUM
]
3091 = unique_base_value (UNIQUE_BASE_VALUE_FP
);
3092 if (!HARD_FRAME_POINTER_IS_FRAME_POINTER
)
3093 static_reg_base_value
[HARD_FRAME_POINTER_REGNUM
]
3094 = unique_base_value (UNIQUE_BASE_VALUE_HFP
);
3097 /* Set MEMORY_MODIFIED when X modifies DATA (that is assumed
3098 to be memory reference. */
3099 static bool memory_modified
;
3101 memory_modified_1 (rtx x
, const_rtx pat ATTRIBUTE_UNUSED
, void *data
)
3105 if (anti_dependence (x
, (const_rtx
)data
) || output_dependence (x
, (const_rtx
)data
))
3106 memory_modified
= true;
3111 /* Return true when INSN possibly modify memory contents of MEM
3112 (i.e. address can be modified). */
3114 memory_modified_in_insn_p (const_rtx mem
, const_rtx insn
)
3118 memory_modified
= false;
3119 note_stores (PATTERN (insn
), memory_modified_1
, CONST_CAST_RTX(mem
));
3120 return memory_modified
;
3123 /* Return TRUE if the destination of a set is rtx identical to
3126 set_dest_equal_p (const_rtx set
, const_rtx item
)
3128 rtx dest
= SET_DEST (set
);
3129 return rtx_equal_p (dest
, item
);
3132 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
3136 init_alias_analysis (void)
3138 unsigned int maxreg
= max_reg_num ();
3147 timevar_push (TV_ALIAS_ANALYSIS
);
3149 vec_safe_grow_cleared (reg_known_value
, maxreg
- FIRST_PSEUDO_REGISTER
);
3150 reg_known_equiv_p
= sbitmap_alloc (maxreg
- FIRST_PSEUDO_REGISTER
);
3151 bitmap_clear (reg_known_equiv_p
);
3153 /* If we have memory allocated from the previous run, use it. */
3154 if (old_reg_base_value
)
3155 reg_base_value
= old_reg_base_value
;
3158 reg_base_value
->truncate (0);
3160 vec_safe_grow_cleared (reg_base_value
, maxreg
);
3162 new_reg_base_value
= XNEWVEC (rtx
, maxreg
);
3163 reg_seen
= sbitmap_alloc (maxreg
);
3165 /* The basic idea is that each pass through this loop will use the
3166 "constant" information from the previous pass to propagate alias
3167 information through another level of assignments.
3169 The propagation is done on the CFG in reverse post-order, to propagate
3170 things forward as far as possible in each iteration.
3172 This could get expensive if the assignment chains are long. Maybe
3173 we should throttle the number of iterations, possibly based on
3174 the optimization level or flag_expensive_optimizations.
3176 We could propagate more information in the first pass by making use
3177 of DF_REG_DEF_COUNT to determine immediately that the alias information
3178 for a pseudo is "constant".
3180 A program with an uninitialized variable can cause an infinite loop
3181 here. Instead of doing a full dataflow analysis to detect such problems
3182 we just cap the number of iterations for the loop.
3184 The state of the arrays for the set chain in question does not matter
3185 since the program has undefined behavior. */
3187 rpo
= XNEWVEC (int, n_basic_blocks_for_fn (cfun
));
3188 rpo_cnt
= pre_and_rev_post_order_compute (NULL
, rpo
, false);
3190 /* The prologue/epilogue insns are not threaded onto the
3191 insn chain until after reload has completed. Thus,
3192 there is no sense wasting time checking if INSN is in
3193 the prologue/epilogue until after reload has completed. */
3194 bool could_be_prologue_epilogue
= ((targetm
.have_prologue ()
3195 || targetm
.have_epilogue ())
3196 && reload_completed
);
3201 /* Assume nothing will change this iteration of the loop. */
3204 /* We want to assign the same IDs each iteration of this loop, so
3205 start counting from one each iteration of the loop. */
3208 /* We're at the start of the function each iteration through the
3209 loop, so we're copying arguments. */
3210 copying_arguments
= true;
3212 /* Wipe the potential alias information clean for this pass. */
3213 memset (new_reg_base_value
, 0, maxreg
* sizeof (rtx
));
3215 /* Wipe the reg_seen array clean. */
3216 bitmap_clear (reg_seen
);
3218 /* Initialize the alias information for this pass. */
3219 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3220 if (static_reg_base_value
[i
])
3222 new_reg_base_value
[i
] = static_reg_base_value
[i
];
3223 bitmap_set_bit (reg_seen
, i
);
3226 /* Walk the insns adding values to the new_reg_base_value array. */
3227 for (i
= 0; i
< rpo_cnt
; i
++)
3229 basic_block bb
= BASIC_BLOCK_FOR_FN (cfun
, rpo
[i
]);
3230 FOR_BB_INSNS (bb
, insn
)
3232 if (NONDEBUG_INSN_P (insn
))
3236 if (could_be_prologue_epilogue
3237 && prologue_epilogue_contains (insn
))
3240 /* If this insn has a noalias note, process it, Otherwise,
3241 scan for sets. A simple set will have no side effects
3242 which could change the base value of any other register. */
3244 if (GET_CODE (PATTERN (insn
)) == SET
3245 && REG_NOTES (insn
) != 0
3246 && find_reg_note (insn
, REG_NOALIAS
, NULL_RTX
))
3247 record_set (SET_DEST (PATTERN (insn
)), NULL_RTX
, NULL
);
3249 note_stores (PATTERN (insn
), record_set
, NULL
);
3251 set
= single_set (insn
);
3254 && REG_P (SET_DEST (set
))
3255 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
)
3257 unsigned int regno
= REGNO (SET_DEST (set
));
3258 rtx src
= SET_SRC (set
);
3261 note
= find_reg_equal_equiv_note (insn
);
3262 if (note
&& REG_NOTE_KIND (note
) == REG_EQUAL
3263 && DF_REG_DEF_COUNT (regno
) != 1)
3266 if (note
!= NULL_RTX
3267 && GET_CODE (XEXP (note
, 0)) != EXPR_LIST
3268 && ! rtx_varies_p (XEXP (note
, 0), 1)
3269 && ! reg_overlap_mentioned_p (SET_DEST (set
),
3272 set_reg_known_value (regno
, XEXP (note
, 0));
3273 set_reg_known_equiv_p (regno
,
3274 REG_NOTE_KIND (note
) == REG_EQUIV
);
3276 else if (DF_REG_DEF_COUNT (regno
) == 1
3277 && GET_CODE (src
) == PLUS
3278 && REG_P (XEXP (src
, 0))
3279 && (t
= get_reg_known_value (REGNO (XEXP (src
, 0))))
3280 && CONST_INT_P (XEXP (src
, 1)))
3282 t
= plus_constant (GET_MODE (src
), t
,
3283 INTVAL (XEXP (src
, 1)));
3284 set_reg_known_value (regno
, t
);
3285 set_reg_known_equiv_p (regno
, false);
3287 else if (DF_REG_DEF_COUNT (regno
) == 1
3288 && ! rtx_varies_p (src
, 1))
3290 set_reg_known_value (regno
, src
);
3291 set_reg_known_equiv_p (regno
, false);
3295 else if (NOTE_P (insn
)
3296 && NOTE_KIND (insn
) == NOTE_INSN_FUNCTION_BEG
)
3297 copying_arguments
= false;
3301 /* Now propagate values from new_reg_base_value to reg_base_value. */
3302 gcc_assert (maxreg
== (unsigned int) max_reg_num ());
3304 for (ui
= 0; ui
< maxreg
; ui
++)
3306 if (new_reg_base_value
[ui
]
3307 && new_reg_base_value
[ui
] != (*reg_base_value
)[ui
]
3308 && ! rtx_equal_p (new_reg_base_value
[ui
], (*reg_base_value
)[ui
]))
3310 (*reg_base_value
)[ui
] = new_reg_base_value
[ui
];
3315 while (changed
&& ++pass
< MAX_ALIAS_LOOP_PASSES
);
3318 /* Fill in the remaining entries. */
3319 FOR_EACH_VEC_ELT (*reg_known_value
, i
, val
)
3321 int regno
= i
+ FIRST_PSEUDO_REGISTER
;
3323 set_reg_known_value (regno
, regno_reg_rtx
[regno
]);
3327 free (new_reg_base_value
);
3328 new_reg_base_value
= 0;
3329 sbitmap_free (reg_seen
);
3331 timevar_pop (TV_ALIAS_ANALYSIS
);
3334 /* Equate REG_BASE_VALUE (reg1) to REG_BASE_VALUE (reg2).
3335 Special API for var-tracking pass purposes. */
3338 vt_equate_reg_base_value (const_rtx reg1
, const_rtx reg2
)
3340 (*reg_base_value
)[REGNO (reg1
)] = REG_BASE_VALUE (reg2
);
3344 end_alias_analysis (void)
3346 old_reg_base_value
= reg_base_value
;
3347 vec_free (reg_known_value
);
3348 sbitmap_free (reg_known_equiv_p
);
3352 dump_alias_stats_in_alias_c (FILE *s
)
3354 fprintf (s
, " TBAA oracle: %llu disambiguations %llu queries\n"
3355 " %llu are in alias set 0\n"
3356 " %llu queries asked about the same object\n"
3357 " %llu queries asked about the same alias set\n"
3358 " %llu access volatile\n"
3359 " %llu are dependent in the DAG\n"
3360 " %llu are aritificially in conflict with void *\n",
3361 alias_stats
.num_disambiguated
,
3362 alias_stats
.num_alias_zero
+ alias_stats
.num_same_alias_set
3363 + alias_stats
.num_same_objects
+ alias_stats
.num_volatile
3364 + alias_stats
.num_dag
+ alias_stats
.num_disambiguated
3365 + alias_stats
.num_universal
,
3366 alias_stats
.num_alias_zero
, alias_stats
.num_same_alias_set
,
3367 alias_stats
.num_same_objects
, alias_stats
.num_volatile
,
3368 alias_stats
.num_dag
, alias_stats
.num_universal
);
3370 #include "gt-alias.h"