1 /* Alias analysis for GNU C
2 Copyright (C) 1997-2015 Free Software Foundation, Inc.
3 Contributed by John Carr (jfc@mit.edu).
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
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"
41 /* The aliasing API provided here solves related but different problems:
43 Say there exists (in c)
57 Consider the four questions:
59 Can a store to x1 interfere with px2->y1?
60 Can a store to x1 interfere with px2->z2?
61 Can a store to x1 change the value pointed to by with py?
62 Can a store to x1 change the value pointed to by with pz?
64 The answer to these questions can be yes, yes, yes, and maybe.
66 The first two questions can be answered with a simple examination
67 of the type system. If structure X contains a field of type Y then
68 a store through a pointer to an X can overwrite any field that is
69 contained (recursively) in an X (unless we know that px1 != px2).
71 The last two questions can be solved in the same way as the first
72 two questions but this is too conservative. The observation is
73 that in some cases we can know which (if any) fields are addressed
74 and if those addresses are used in bad ways. This analysis may be
75 language specific. In C, arbitrary operations may be applied to
76 pointers. However, there is some indication that this may be too
77 conservative for some C++ types.
79 The pass ipa-type-escape does this analysis for the types whose
80 instances do not escape across the compilation boundary.
82 Historically in GCC, these two problems were combined and a single
83 data structure that was used to represent the solution to these
84 problems. We now have two similar but different data structures,
85 The data structure to solve the last two questions is similar to
86 the first, but does not contain the fields whose address are never
87 taken. For types that do escape the compilation unit, the data
88 structures will have identical information.
91 /* The alias sets assigned to MEMs assist the back-end in determining
92 which MEMs can alias which other MEMs. In general, two MEMs in
93 different alias sets cannot alias each other, with one important
94 exception. Consider something like:
96 struct S { int i; double d; };
98 a store to an `S' can alias something of either type `int' or type
99 `double'. (However, a store to an `int' cannot alias a `double'
100 and vice versa.) We indicate this via a tree structure that looks
108 (The arrows are directed and point downwards.)
109 In this situation we say the alias set for `struct S' is the
110 `superset' and that those for `int' and `double' are `subsets'.
112 To see whether two alias sets can point to the same memory, we must
113 see if either alias set is a subset of the other. We need not trace
114 past immediate descendants, however, since we propagate all
115 grandchildren up one level.
117 Alias set zero is implicitly a superset of all other alias sets.
118 However, this is no actual entry for alias set zero. It is an
119 error to attempt to explicitly construct a subset of zero. */
121 struct alias_set_hash
: int_hash
<int, INT_MIN
, INT_MIN
+ 1> {};
123 struct GTY(()) alias_set_entry
{
124 /* The alias set number, as stored in MEM_ALIAS_SET. */
125 alias_set_type alias_set
;
127 /* The children of the alias set. These are not just the immediate
128 children, but, in fact, all descendants. So, if we have:
130 struct T { struct S s; float f; }
132 continuing our example above, the children here will be all of
133 `int', `double', `float', and `struct S'. */
134 hash_map
<alias_set_hash
, int> *children
;
136 /* Nonzero if would have a child of zero: this effectively makes this
137 alias set the same as alias set zero. */
139 /* Nonzero if alias set corresponds to pointer type itself (i.e. not to
140 aggregate contaiing pointer.
141 This is used for a special case where we need an universal pointer type
142 compatible with all other pointer types. */
144 /* Nonzero if is_pointer or if one of childs have has_pointer set. */
148 static int rtx_equal_for_memref_p (const_rtx
, const_rtx
);
149 static int memrefs_conflict_p (int, rtx
, int, rtx
, HOST_WIDE_INT
);
150 static void record_set (rtx
, const_rtx
, void *);
151 static int base_alias_check (rtx
, rtx
, rtx
, rtx
, machine_mode
,
153 static rtx
find_base_value (rtx
);
154 static int mems_in_disjoint_alias_sets_p (const_rtx
, const_rtx
);
155 static alias_set_entry
*get_alias_set_entry (alias_set_type
);
156 static tree
decl_for_component_ref (tree
);
157 static int write_dependence_p (const_rtx
,
158 const_rtx
, machine_mode
, rtx
,
161 static void memory_modified_1 (rtx
, const_rtx
, void *);
163 /* Query statistics for the different low-level disambiguators.
164 A high-level query may trigger multiple of them. */
167 unsigned long long num_alias_zero
;
168 unsigned long long num_same_alias_set
;
169 unsigned long long num_same_objects
;
170 unsigned long long num_volatile
;
171 unsigned long long num_dag
;
172 unsigned long long num_universal
;
173 unsigned long long num_disambiguated
;
177 /* Set up all info needed to perform alias analysis on memory references. */
179 /* Returns the size in bytes of the mode of X. */
180 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
182 /* Cap the number of passes we make over the insns propagating alias
183 information through set chains.
184 ??? 10 is a completely arbitrary choice. This should be based on the
185 maximum loop depth in the CFG, but we do not have this information
186 available (even if current_loops _is_ available). */
187 #define MAX_ALIAS_LOOP_PASSES 10
189 /* reg_base_value[N] gives an address to which register N is related.
190 If all sets after the first add or subtract to the current value
191 or otherwise modify it so it does not point to a different top level
192 object, reg_base_value[N] is equal to the address part of the source
195 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
196 expressions represent three types of base:
198 1. incoming arguments. There is just one ADDRESS to represent all
199 arguments, since we do not know at this level whether accesses
200 based on different arguments can alias. The ADDRESS has id 0.
202 2. stack_pointer_rtx, frame_pointer_rtx, hard_frame_pointer_rtx
203 (if distinct from frame_pointer_rtx) and arg_pointer_rtx.
204 Each of these rtxes has a separate ADDRESS associated with it,
205 each with a negative id.
207 GCC is (and is required to be) precise in which register it
208 chooses to access a particular region of stack. We can therefore
209 assume that accesses based on one of these rtxes do not alias
210 accesses based on another of these rtxes.
212 3. bases that are derived from malloc()ed memory (REG_NOALIAS).
213 Each such piece of memory has a separate ADDRESS associated
214 with it, each with an id greater than 0.
216 Accesses based on one ADDRESS do not alias accesses based on other
217 ADDRESSes. Accesses based on ADDRESSes in groups (2) and (3) do not
218 alias globals either; the ADDRESSes have Pmode to indicate this.
219 The ADDRESS in group (1) _may_ alias globals; it has VOIDmode to
222 static GTY(()) vec
<rtx
, va_gc
> *reg_base_value
;
223 static rtx
*new_reg_base_value
;
225 /* The single VOIDmode ADDRESS that represents all argument bases.
227 static GTY(()) rtx arg_base_value
;
229 /* Used to allocate unique ids to each REG_NOALIAS ADDRESS. */
230 static int unique_id
;
232 /* We preserve the copy of old array around to avoid amount of garbage
233 produced. About 8% of garbage produced were attributed to this
235 static GTY((deletable
)) vec
<rtx
, va_gc
> *old_reg_base_value
;
237 /* Values of XINT (address, 0) of Pmode ADDRESS rtxes for special
239 #define UNIQUE_BASE_VALUE_SP -1
240 #define UNIQUE_BASE_VALUE_ARGP -2
241 #define UNIQUE_BASE_VALUE_FP -3
242 #define UNIQUE_BASE_VALUE_HFP -4
244 #define static_reg_base_value \
245 (this_target_rtl->x_static_reg_base_value)
247 #define REG_BASE_VALUE(X) \
248 (REGNO (X) < vec_safe_length (reg_base_value) \
249 ? (*reg_base_value)[REGNO (X)] : 0)
251 /* Vector indexed by N giving the initial (unchanging) value known for
252 pseudo-register N. This vector is initialized in init_alias_analysis,
253 and does not change until end_alias_analysis is called. */
254 static GTY(()) vec
<rtx
, va_gc
> *reg_known_value
;
256 /* Vector recording for each reg_known_value whether it is due to a
257 REG_EQUIV note. Future passes (viz., reload) may replace the
258 pseudo with the equivalent expression and so we account for the
259 dependences that would be introduced if that happens.
261 The REG_EQUIV notes created in assign_parms may mention the arg
262 pointer, and there are explicit insns in the RTL that modify the
263 arg pointer. Thus we must ensure that such insns don't get
264 scheduled across each other because that would invalidate the
265 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
266 wrong, but solving the problem in the scheduler will likely give
267 better code, so we do it here. */
268 static sbitmap reg_known_equiv_p
;
270 /* True when scanning insns from the start of the rtl to the
271 NOTE_INSN_FUNCTION_BEG note. */
272 static bool copying_arguments
;
275 /* The splay-tree used to store the various alias set entries. */
276 static GTY (()) vec
<alias_set_entry
*, va_gc
> *alias_sets
;
278 /* Build a decomposed reference object for querying the alias-oracle
279 from the MEM rtx and store it in *REF.
280 Returns false if MEM is not suitable for the alias-oracle. */
283 ao_ref_from_mem (ao_ref
*ref
, const_rtx mem
)
285 tree expr
= MEM_EXPR (mem
);
291 ao_ref_init (ref
, expr
);
293 /* Get the base of the reference and see if we have to reject or
295 base
= ao_ref_base (ref
);
296 if (base
== NULL_TREE
)
299 /* The tree oracle doesn't like bases that are neither decls
300 nor indirect references of SSA names. */
302 || (TREE_CODE (base
) == MEM_REF
303 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
304 || (TREE_CODE (base
) == TARGET_MEM_REF
305 && TREE_CODE (TMR_BASE (base
)) == SSA_NAME
)))
308 /* If this is a reference based on a partitioned decl replace the
309 base with a MEM_REF of the pointer representative we
310 created during stack slot partitioning. */
311 if (TREE_CODE (base
) == VAR_DECL
312 && ! is_global_var (base
)
313 && cfun
->gimple_df
->decls_to_pointers
!= NULL
)
315 tree
*namep
= cfun
->gimple_df
->decls_to_pointers
->get (base
);
317 ref
->base
= build_simple_mem_ref (*namep
);
320 ref
->ref_alias_set
= MEM_ALIAS_SET (mem
);
322 /* If MEM_OFFSET or MEM_SIZE are unknown what we got from MEM_EXPR
323 is conservative, so trust it. */
324 if (!MEM_OFFSET_KNOWN_P (mem
)
325 || !MEM_SIZE_KNOWN_P (mem
))
328 /* If MEM_OFFSET/MEM_SIZE get us outside of ref->offset/ref->max_size
330 if (MEM_OFFSET (mem
) < 0
331 || (ref
->max_size
!= -1
332 && ((MEM_OFFSET (mem
) + MEM_SIZE (mem
)) * BITS_PER_UNIT
334 ref
->ref
= NULL_TREE
;
336 /* Refine size and offset we got from analyzing MEM_EXPR by using
337 MEM_SIZE and MEM_OFFSET. */
339 ref
->offset
+= MEM_OFFSET (mem
) * BITS_PER_UNIT
;
340 ref
->size
= MEM_SIZE (mem
) * BITS_PER_UNIT
;
342 /* The MEM may extend into adjacent fields, so adjust max_size if
344 if (ref
->max_size
!= -1
345 && ref
->size
> ref
->max_size
)
346 ref
->max_size
= ref
->size
;
348 /* If MEM_OFFSET and MEM_SIZE get us outside of the base object of
349 the MEM_EXPR punt. This happens for STRICT_ALIGNMENT targets a lot. */
350 if (MEM_EXPR (mem
) != get_spill_slot_decl (false)
352 || (DECL_P (ref
->base
)
353 && (DECL_SIZE (ref
->base
) == NULL_TREE
354 || TREE_CODE (DECL_SIZE (ref
->base
)) != INTEGER_CST
355 || wi::ltu_p (wi::to_offset (DECL_SIZE (ref
->base
)),
356 ref
->offset
+ ref
->size
)))))
362 /* Query the alias-oracle on whether the two memory rtx X and MEM may
363 alias. If TBAA_P is set also apply TBAA. Returns true if the
364 two rtxen may alias, false otherwise. */
367 rtx_refs_may_alias_p (const_rtx x
, const_rtx mem
, bool tbaa_p
)
371 if (!ao_ref_from_mem (&ref1
, x
)
372 || !ao_ref_from_mem (&ref2
, mem
))
375 return refs_may_alias_p_1 (&ref1
, &ref2
,
377 && MEM_ALIAS_SET (x
) != 0
378 && MEM_ALIAS_SET (mem
) != 0);
381 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
382 such an entry, or NULL otherwise. */
384 static inline alias_set_entry
*
385 get_alias_set_entry (alias_set_type alias_set
)
387 return (*alias_sets
)[alias_set
];
390 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
391 the two MEMs cannot alias each other. */
394 mems_in_disjoint_alias_sets_p (const_rtx mem1
, const_rtx mem2
)
396 return (flag_strict_aliasing
397 && ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1
),
398 MEM_ALIAS_SET (mem2
)));
401 /* Return true if the first alias set is a subset of the second. */
404 alias_set_subset_of (alias_set_type set1
, alias_set_type set2
)
406 alias_set_entry
*ase2
;
408 /* Everything is a subset of the "aliases everything" set. */
412 /* Check if set1 is a subset of set2. */
413 ase2
= get_alias_set_entry (set2
);
415 && (ase2
->has_zero_child
416 || (ase2
->children
&& ase2
->children
->get (set1
))))
419 /* As a special case we consider alias set of "void *" to be both subset
420 and superset of every alias set of a pointer. This extra symmetry does
421 not matter for alias_sets_conflict_p but it makes aliasing_component_refs_p
422 to return true on the following testcase:
425 char **ptr2=(char **)&ptr;
428 Additionally if a set contains universal pointer, we consider every pointer
429 to be a subset of it, but we do not represent this explicitely - doing so
430 would require us to update transitive closure each time we introduce new
431 pointer type. This makes aliasing_component_refs_p to return true
432 on the following testcase:
434 struct a {void *ptr;}
435 char **ptr = (char **)&a.ptr;
438 This makes void * truly universal pointer type. See pointer handling in
439 get_alias_set for more details. */
440 if (ase2
&& ase2
->has_pointer
)
442 alias_set_entry
*ase1
= get_alias_set_entry (set1
);
444 if (ase1
&& ase1
->is_pointer
)
446 alias_set_type voidptr_set
= TYPE_ALIAS_SET (ptr_type_node
);
447 /* If one is ptr_type_node and other is pointer, then we consider
448 them subset of each other. */
449 if (set1
== voidptr_set
|| set2
== voidptr_set
)
451 /* If SET2 contains universal pointer's alias set, then we consdier
452 every (non-universal) pointer. */
453 if (ase2
->children
&& set1
!= voidptr_set
454 && ase2
->children
->get (voidptr_set
))
461 /* Return 1 if the two specified alias sets may conflict. */
464 alias_sets_conflict_p (alias_set_type set1
, alias_set_type set2
)
466 alias_set_entry
*ase1
;
467 alias_set_entry
*ase2
;
470 if (alias_sets_must_conflict_p (set1
, set2
))
473 /* See if the first alias set is a subset of the second. */
474 ase1
= get_alias_set_entry (set1
);
476 && ase1
->children
&& ase1
->children
->get (set2
))
478 ++alias_stats
.num_dag
;
482 /* Now do the same, but with the alias sets reversed. */
483 ase2
= get_alias_set_entry (set2
);
485 && ase2
->children
&& ase2
->children
->get (set1
))
487 ++alias_stats
.num_dag
;
491 /* We want void * to be compatible with any other pointer without
492 really dropping it to alias set 0. Doing so would make it
493 compatible with all non-pointer types too.
495 This is not strictly necessary by the C/C++ language
496 standards, but avoids common type punning mistakes. In
497 addition to that, we need the existence of such universal
498 pointer to implement Fortran's C_PTR type (which is defined as
499 type compatible with all C pointers). */
500 if (ase1
&& ase2
&& ase1
->has_pointer
&& ase2
->has_pointer
)
502 alias_set_type voidptr_set
= TYPE_ALIAS_SET (ptr_type_node
);
504 /* If one of the sets corresponds to universal pointer,
505 we consider it to conflict with anything that is
506 or contains pointer. */
507 if (set1
== voidptr_set
|| set2
== voidptr_set
)
509 ++alias_stats
.num_universal
;
512 /* If one of sets is (non-universal) pointer and the other
513 contains universal pointer, we also get conflict. */
514 if (ase1
->is_pointer
&& set2
!= voidptr_set
515 && ase2
->children
&& ase2
->children
->get (voidptr_set
))
517 ++alias_stats
.num_universal
;
520 if (ase2
->is_pointer
&& set1
!= voidptr_set
521 && ase1
->children
&& ase1
->children
->get (voidptr_set
))
523 ++alias_stats
.num_universal
;
528 ++alias_stats
.num_disambiguated
;
530 /* The two alias sets are distinct and neither one is the
531 child of the other. Therefore, they cannot conflict. */
535 /* Return 1 if the two specified alias sets will always conflict. */
538 alias_sets_must_conflict_p (alias_set_type set1
, alias_set_type set2
)
540 if (set1
== 0 || set2
== 0)
542 ++alias_stats
.num_alias_zero
;
547 ++alias_stats
.num_same_alias_set
;
554 /* Return 1 if any MEM object of type T1 will always conflict (using the
555 dependency routines in this file) with any MEM object of type T2.
556 This is used when allocating temporary storage. If T1 and/or T2 are
557 NULL_TREE, it means we know nothing about the storage. */
560 objects_must_conflict_p (tree t1
, tree t2
)
562 alias_set_type set1
, set2
;
564 /* If neither has a type specified, we don't know if they'll conflict
565 because we may be using them to store objects of various types, for
566 example the argument and local variables areas of inlined functions. */
567 if (t1
== 0 && t2
== 0)
570 /* If they are the same type, they must conflict. */
573 ++alias_stats
.num_same_objects
;
576 /* Likewise if both are volatile. */
577 if (t1
!= 0 && TYPE_VOLATILE (t1
) && t2
!= 0 && TYPE_VOLATILE (t2
))
579 ++alias_stats
.num_volatile
;
583 set1
= t1
? get_alias_set (t1
) : 0;
584 set2
= t2
? get_alias_set (t2
) : 0;
586 /* We can't use alias_sets_conflict_p because we must make sure
587 that every subtype of t1 will conflict with every subtype of
588 t2 for which a pair of subobjects of these respective subtypes
589 overlaps on the stack. */
590 return alias_sets_must_conflict_p (set1
, set2
);
593 /* Return the outermost parent of component present in the chain of
594 component references handled by get_inner_reference in T with the
596 - the component is non-addressable, or
597 - the parent has alias set zero,
598 or NULL_TREE if no such parent exists. In the former cases, the alias
599 set of this parent is the alias set that must be used for T itself. */
602 component_uses_parent_alias_set_from (const_tree t
)
604 const_tree found
= NULL_TREE
;
606 while (handled_component_p (t
))
608 switch (TREE_CODE (t
))
611 if (DECL_NONADDRESSABLE_P (TREE_OPERAND (t
, 1)))
616 case ARRAY_RANGE_REF
:
617 if (TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t
, 0))))
626 case VIEW_CONVERT_EXPR
:
627 /* Bitfields and casts are never addressable. */
635 if (get_alias_set (TREE_TYPE (TREE_OPERAND (t
, 0))) == 0)
638 t
= TREE_OPERAND (t
, 0);
642 return TREE_OPERAND (found
, 0);
648 /* Return whether the pointer-type T effective for aliasing may
649 access everything and thus the reference has to be assigned
653 ref_all_alias_ptr_type_p (const_tree t
)
655 return (TREE_CODE (TREE_TYPE (t
)) == VOID_TYPE
656 || TYPE_REF_CAN_ALIAS_ALL (t
));
659 /* Return the alias set for the memory pointed to by T, which may be
660 either a type or an expression. Return -1 if there is nothing
661 special about dereferencing T. */
663 static alias_set_type
664 get_deref_alias_set_1 (tree t
)
666 /* All we care about is the type. */
670 /* If we have an INDIRECT_REF via a void pointer, we don't
671 know anything about what that might alias. Likewise if the
672 pointer is marked that way. */
673 if (ref_all_alias_ptr_type_p (t
))
679 /* Return the alias set for the memory pointed to by T, which may be
680 either a type or an expression. */
683 get_deref_alias_set (tree t
)
685 /* If we're not doing any alias analysis, just assume everything
686 aliases everything else. */
687 if (!flag_strict_aliasing
)
690 alias_set_type set
= get_deref_alias_set_1 (t
);
692 /* Fall back to the alias-set of the pointed-to type. */
697 set
= get_alias_set (TREE_TYPE (t
));
703 /* Return the pointer-type relevant for TBAA purposes from the
704 memory reference tree *T or NULL_TREE in which case *T is
705 adjusted to point to the outermost component reference that
706 can be used for assigning an alias set. */
709 reference_alias_ptr_type_1 (tree
*t
)
713 /* Get the base object of the reference. */
715 while (handled_component_p (inner
))
717 /* If there is a VIEW_CONVERT_EXPR in the chain we cannot use
718 the type of any component references that wrap it to
719 determine the alias-set. */
720 if (TREE_CODE (inner
) == VIEW_CONVERT_EXPR
)
721 *t
= TREE_OPERAND (inner
, 0);
722 inner
= TREE_OPERAND (inner
, 0);
725 /* Handle pointer dereferences here, they can override the
727 if (INDIRECT_REF_P (inner
)
728 && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner
, 0))))
729 return TREE_TYPE (TREE_OPERAND (inner
, 0));
730 else if (TREE_CODE (inner
) == TARGET_MEM_REF
)
731 return TREE_TYPE (TMR_OFFSET (inner
));
732 else if (TREE_CODE (inner
) == MEM_REF
733 && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner
, 1))))
734 return TREE_TYPE (TREE_OPERAND (inner
, 1));
736 /* If the innermost reference is a MEM_REF that has a
737 conversion embedded treat it like a VIEW_CONVERT_EXPR above,
738 using the memory access type for determining the alias-set. */
739 if (TREE_CODE (inner
) == MEM_REF
740 && (TYPE_MAIN_VARIANT (TREE_TYPE (inner
))
742 (TREE_TYPE (TREE_TYPE (TREE_OPERAND (inner
, 1))))))
743 return TREE_TYPE (TREE_OPERAND (inner
, 1));
745 /* Otherwise, pick up the outermost object that we could have
747 tree tem
= component_uses_parent_alias_set_from (*t
);
754 /* Return the pointer-type relevant for TBAA purposes from the
755 gimple memory reference tree T. This is the type to be used for
756 the offset operand of MEM_REF or TARGET_MEM_REF replacements of T
757 and guarantees that get_alias_set will return the same alias
758 set for T and the replacement. */
761 reference_alias_ptr_type (tree t
)
763 tree ptype
= reference_alias_ptr_type_1 (&t
);
764 /* If there is a given pointer type for aliasing purposes, return it. */
765 if (ptype
!= NULL_TREE
)
768 /* Otherwise build one from the outermost component reference we
770 if (TREE_CODE (t
) == MEM_REF
771 || TREE_CODE (t
) == TARGET_MEM_REF
)
772 return TREE_TYPE (TREE_OPERAND (t
, 1));
774 return build_pointer_type (TYPE_MAIN_VARIANT (TREE_TYPE (t
)));
777 /* Return whether the pointer-types T1 and T2 used to determine
778 two alias sets of two references will yield the same answer
779 from get_deref_alias_set. */
782 alias_ptr_types_compatible_p (tree t1
, tree t2
)
784 if (TYPE_MAIN_VARIANT (t1
) == TYPE_MAIN_VARIANT (t2
))
787 if (ref_all_alias_ptr_type_p (t1
)
788 || ref_all_alias_ptr_type_p (t2
))
791 return (TYPE_MAIN_VARIANT (TREE_TYPE (t1
))
792 == TYPE_MAIN_VARIANT (TREE_TYPE (t2
)));
795 /* Create emptry alias set entry. */
798 init_alias_set_entry (alias_set_type set
)
800 alias_set_entry
*ase
= ggc_alloc
<alias_set_entry
> ();
801 ase
->alias_set
= set
;
802 ase
->children
= NULL
;
803 ase
->has_zero_child
= false;
804 ase
->is_pointer
= false;
805 ase
->has_pointer
= false;
806 gcc_checking_assert (!get_alias_set_entry (set
));
807 (*alias_sets
)[set
] = ase
;
811 /* Return the alias set for T, which may be either a type or an
812 expression. Call language-specific routine for help, if needed. */
815 get_alias_set (tree t
)
819 /* If we're not doing any alias analysis, just assume everything
820 aliases everything else. Also return 0 if this or its type is
822 if (! flag_strict_aliasing
|| t
== error_mark_node
824 && (TREE_TYPE (t
) == 0 || TREE_TYPE (t
) == error_mark_node
)))
827 /* We can be passed either an expression or a type. This and the
828 language-specific routine may make mutually-recursive calls to each other
829 to figure out what to do. At each juncture, we see if this is a tree
830 that the language may need to handle specially. First handle things that
834 /* Give the language a chance to do something with this tree
835 before we look at it. */
837 set
= lang_hooks
.get_alias_set (t
);
841 /* Get the alias pointer-type to use or the outermost object
842 that we could have a pointer to. */
843 tree ptype
= reference_alias_ptr_type_1 (&t
);
845 return get_deref_alias_set (ptype
);
847 /* If we've already determined the alias set for a decl, just return
848 it. This is necessary for C++ anonymous unions, whose component
849 variables don't look like union members (boo!). */
850 if (TREE_CODE (t
) == VAR_DECL
851 && DECL_RTL_SET_P (t
) && MEM_P (DECL_RTL (t
)))
852 return MEM_ALIAS_SET (DECL_RTL (t
));
854 /* Now all we care about is the type. */
858 /* Variant qualifiers don't affect the alias set, so get the main
860 t
= TYPE_MAIN_VARIANT (t
);
862 /* Always use the canonical type as well. If this is a type that
863 requires structural comparisons to identify compatible types
864 use alias set zero. */
865 if (TYPE_STRUCTURAL_EQUALITY_P (t
))
867 /* Allow the language to specify another alias set for this
869 set
= lang_hooks
.get_alias_set (t
);
872 /* Handle structure type equality for pointer types, arrays and vectors.
873 This is easy to do, because the code bellow ignore canonical types on
874 these anyway. This is important for LTO, where TYPE_CANONICAL for
875 pointers can not be meaningfuly computed by the frotnend. */
876 if (canonical_type_used_p (t
))
878 /* In LTO we set canonical types for all types where it makes
879 sense to do so. Double check we did not miss some type. */
880 gcc_checking_assert (!in_lto_p
|| !type_with_alias_set_p (t
));
886 t
= TYPE_CANONICAL (t
);
887 gcc_checking_assert (!TYPE_STRUCTURAL_EQUALITY_P (t
));
890 /* If this is a type with a known alias set, return it. */
891 gcc_checking_assert (t
== TYPE_MAIN_VARIANT (t
));
892 if (TYPE_ALIAS_SET_KNOWN_P (t
))
893 return TYPE_ALIAS_SET (t
);
895 /* We don't want to set TYPE_ALIAS_SET for incomplete types. */
896 if (!COMPLETE_TYPE_P (t
))
898 /* For arrays with unknown size the conservative answer is the
899 alias set of the element type. */
900 if (TREE_CODE (t
) == ARRAY_TYPE
)
901 return get_alias_set (TREE_TYPE (t
));
903 /* But return zero as a conservative answer for incomplete types. */
907 /* See if the language has special handling for this type. */
908 set
= lang_hooks
.get_alias_set (t
);
912 /* There are no objects of FUNCTION_TYPE, so there's no point in
913 using up an alias set for them. (There are, of course, pointers
914 and references to functions, but that's different.) */
915 else if (TREE_CODE (t
) == FUNCTION_TYPE
|| TREE_CODE (t
) == METHOD_TYPE
)
918 /* Unless the language specifies otherwise, let vector types alias
919 their components. This avoids some nasty type punning issues in
920 normal usage. And indeed lets vectors be treated more like an
922 else if (TREE_CODE (t
) == VECTOR_TYPE
)
923 set
= get_alias_set (TREE_TYPE (t
));
925 /* Unless the language specifies otherwise, treat array types the
926 same as their components. This avoids the asymmetry we get
927 through recording the components. Consider accessing a
928 character(kind=1) through a reference to a character(kind=1)[1:1].
929 Or consider if we want to assign integer(kind=4)[0:D.1387] and
930 integer(kind=4)[4] the same alias set or not.
931 Just be pragmatic here and make sure the array and its element
932 type get the same alias set assigned. */
933 else if (TREE_CODE (t
) == ARRAY_TYPE
934 && (!TYPE_NONALIASED_COMPONENT (t
)
935 || TYPE_STRUCTURAL_EQUALITY_P (t
)))
936 set
= get_alias_set (TREE_TYPE (t
));
938 /* From the former common C and C++ langhook implementation:
940 Unfortunately, there is no canonical form of a pointer type.
941 In particular, if we have `typedef int I', then `int *', and
942 `I *' are different types. So, we have to pick a canonical
943 representative. We do this below.
945 Technically, this approach is actually more conservative that
946 it needs to be. In particular, `const int *' and `int *'
947 should be in different alias sets, according to the C and C++
948 standard, since their types are not the same, and so,
949 technically, an `int **' and `const int **' cannot point at
952 But, the standard is wrong. In particular, this code is
957 const int* const* cipp = ipp;
958 And, it doesn't make sense for that to be legal unless you
959 can dereference IPP and CIPP. So, we ignore cv-qualifiers on
960 the pointed-to types. This issue has been reported to the
963 For this reason go to canonical type of the unqalified pointer type.
964 Until GCC 6 this code set all pointers sets to have alias set of
965 ptr_type_node but that is a bad idea, because it prevents disabiguations
966 in between pointers. For Firefox this accounts about 20% of all
967 disambiguations in the program. */
968 else if (POINTER_TYPE_P (t
) && t
!= ptr_type_node
)
971 auto_vec
<bool, 8> reference
;
973 /* Unnest all pointers and references.
974 We also want to make pointer to array/vector equivalent to pointer to
975 its element (see the reasoning above). Skip all those types, too. */
976 for (p
= t
; POINTER_TYPE_P (p
)
977 || (TREE_CODE (p
) == ARRAY_TYPE
978 && (!TYPE_NONALIASED_COMPONENT (p
)
979 || !COMPLETE_TYPE_P (p
)
980 || TYPE_STRUCTURAL_EQUALITY_P (p
)))
981 || TREE_CODE (p
) == VECTOR_TYPE
;
984 if (TREE_CODE (p
) == REFERENCE_TYPE
)
985 /* In LTO we want languages that use references to be compatible
986 with languages that use pointers. */
987 reference
.safe_push (true && !in_lto_p
);
988 if (TREE_CODE (p
) == POINTER_TYPE
)
989 reference
.safe_push (false);
991 p
= TYPE_MAIN_VARIANT (p
);
993 /* Make void * compatible with char * and also void **.
994 Programs are commonly violating TBAA by this.
996 We also make void * to conflict with every pointer
997 (see record_component_aliases) and thus it is safe it to use it for
998 pointers to types with TYPE_STRUCTURAL_EQUALITY_P. */
999 if (TREE_CODE (p
) == VOID_TYPE
|| TYPE_STRUCTURAL_EQUALITY_P (p
))
1000 set
= get_alias_set (ptr_type_node
);
1003 /* Rebuild pointer type starting from canonical types using
1004 unqualified pointers and references only. This way all such
1005 pointers will have the same alias set and will conflict with
1008 Most of time we already have pointers or references of a given type.
1009 If not we build new one just to be sure that if someone later
1010 (probably only middle-end can, as we should assign all alias
1011 classes only after finishing translation unit) builds the pointer
1012 type, the canonical type will match. */
1013 p
= TYPE_CANONICAL (p
);
1014 while (!reference
.is_empty ())
1016 if (reference
.pop ())
1017 p
= build_reference_type (p
);
1019 p
= build_pointer_type (p
);
1020 gcc_checking_assert (p
== TYPE_MAIN_VARIANT (p
));
1021 /* build_pointer_type should always return the canonical type.
1022 For LTO TYPE_CANOINCAL may be NULL, because we do not compute
1023 them. Be sure that frontends do not glob canonical types of
1024 pointers in unexpected way and that p == TYPE_CANONICAL (p)
1025 in all other cases. */
1026 gcc_checking_assert (!TYPE_CANONICAL (p
)
1027 || p
== TYPE_CANONICAL (p
));
1030 /* Assign the alias set to both p and t.
1031 We can not call get_alias_set (p) here as that would trigger
1032 infinite recursion when p == t. In other cases it would just
1033 trigger unnecesary legwork of rebuilding the pointer again. */
1034 gcc_checking_assert (p
== TYPE_MAIN_VARIANT (p
));
1035 if (TYPE_ALIAS_SET_KNOWN_P (p
))
1036 set
= TYPE_ALIAS_SET (p
);
1039 set
= new_alias_set ();
1040 TYPE_ALIAS_SET (p
) = set
;
1044 /* Alias set of ptr_type_node is special and serve as universal pointer which
1045 is TBAA compatible with every other pointer type. Be sure we have the
1046 alias set built even for LTO which otherwise keeps all TYPE_CANONICAL
1047 of pointer types NULL. */
1048 else if (t
== ptr_type_node
)
1049 set
= new_alias_set ();
1051 /* Otherwise make a new alias set for this type. */
1054 /* Each canonical type gets its own alias set, so canonical types
1055 shouldn't form a tree. It doesn't really matter for types
1056 we handle specially above, so only check it where it possibly
1057 would result in a bogus alias set. */
1058 gcc_checking_assert (TYPE_CANONICAL (t
) == t
);
1060 set
= new_alias_set ();
1063 TYPE_ALIAS_SET (t
) = set
;
1065 /* If this is an aggregate type or a complex type, we must record any
1066 component aliasing information. */
1067 if (AGGREGATE_TYPE_P (t
) || TREE_CODE (t
) == COMPLEX_TYPE
)
1068 record_component_aliases (t
);
1070 /* We treat pointer types specially in alias_set_subset_of. */
1071 if (POINTER_TYPE_P (t
) && set
)
1073 alias_set_entry
*ase
= get_alias_set_entry (set
);
1075 ase
= init_alias_set_entry (set
);
1076 ase
->is_pointer
= true;
1077 ase
->has_pointer
= true;
1083 /* Return a brand-new alias set. */
1086 new_alias_set (void)
1088 if (flag_strict_aliasing
)
1090 if (alias_sets
== 0)
1091 vec_safe_push (alias_sets
, (alias_set_entry
*) NULL
);
1092 vec_safe_push (alias_sets
, (alias_set_entry
*) NULL
);
1093 return alias_sets
->length () - 1;
1099 /* Indicate that things in SUBSET can alias things in SUPERSET, but that
1100 not everything that aliases SUPERSET also aliases SUBSET. For example,
1101 in C, a store to an `int' can alias a load of a structure containing an
1102 `int', and vice versa. But it can't alias a load of a 'double' member
1103 of the same structure. Here, the structure would be the SUPERSET and
1104 `int' the SUBSET. This relationship is also described in the comment at
1105 the beginning of this file.
1107 This function should be called only once per SUPERSET/SUBSET pair.
1109 It is illegal for SUPERSET to be zero; everything is implicitly a
1110 subset of alias set zero. */
1113 record_alias_subset (alias_set_type superset
, alias_set_type subset
)
1115 alias_set_entry
*superset_entry
;
1116 alias_set_entry
*subset_entry
;
1118 /* It is possible in complex type situations for both sets to be the same,
1119 in which case we can ignore this operation. */
1120 if (superset
== subset
)
1123 gcc_assert (superset
);
1125 superset_entry
= get_alias_set_entry (superset
);
1126 if (superset_entry
== 0)
1128 /* Create an entry for the SUPERSET, so that we have a place to
1129 attach the SUBSET. */
1130 superset_entry
= init_alias_set_entry (superset
);
1134 superset_entry
->has_zero_child
= 1;
1137 subset_entry
= get_alias_set_entry (subset
);
1138 if (!superset_entry
->children
)
1139 superset_entry
->children
1140 = hash_map
<alias_set_hash
, int>::create_ggc (64);
1141 /* If there is an entry for the subset, enter all of its children
1142 (if they are not already present) as children of the SUPERSET. */
1145 if (subset_entry
->has_zero_child
)
1146 superset_entry
->has_zero_child
= true;
1147 if (subset_entry
->has_pointer
)
1148 superset_entry
->has_pointer
= true;
1150 if (subset_entry
->children
)
1152 hash_map
<alias_set_hash
, int>::iterator iter
1153 = subset_entry
->children
->begin ();
1154 for (; iter
!= subset_entry
->children
->end (); ++iter
)
1155 superset_entry
->children
->put ((*iter
).first
, (*iter
).second
);
1159 /* Enter the SUBSET itself as a child of the SUPERSET. */
1160 superset_entry
->children
->put (subset
, 0);
1164 /* Record that component types of TYPE, if any, are part of that type for
1165 aliasing purposes. For record types, we only record component types
1166 for fields that are not marked non-addressable. For array types, we
1167 only record the component type if it is not marked non-aliased. */
1170 record_component_aliases (tree type
)
1172 alias_set_type superset
= get_alias_set (type
);
1178 switch (TREE_CODE (type
))
1182 case QUAL_UNION_TYPE
:
1183 for (field
= TYPE_FIELDS (type
); field
!= 0; field
= DECL_CHAIN (field
))
1184 if (TREE_CODE (field
) == FIELD_DECL
&& !DECL_NONADDRESSABLE_P (field
))
1186 /* LTO type merging does not make any difference between
1187 component pointer types. We may have
1189 struct foo {int *a;};
1191 as TYPE_CANONICAL of
1193 struct bar {float *a;};
1195 Because accesses to int * and float * do not alias, we would get
1196 false negative when accessing the same memory location by
1197 float ** and bar *. We thus record the canonical type as:
1201 void * is special cased and works as a universal pointer type.
1202 Accesses to it conflicts with accesses to any other pointer
1204 tree t
= TREE_TYPE (field
);
1207 /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their
1208 element type and that type has to be normalized to void *,
1209 too, in the case it is a pointer. */
1210 while (!canonical_type_used_p (t
) && !POINTER_TYPE_P (t
))
1212 gcc_checking_assert (TYPE_STRUCTURAL_EQUALITY_P (t
));
1215 if (POINTER_TYPE_P (t
))
1217 else if (flag_checking
)
1218 gcc_checking_assert (get_alias_set (t
)
1219 == get_alias_set (TREE_TYPE (field
)));
1222 record_alias_subset (superset
, get_alias_set (t
));
1227 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
1230 /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their
1238 /* Allocate an alias set for use in storing and reading from the varargs
1241 static GTY(()) alias_set_type varargs_set
= -1;
1244 get_varargs_alias_set (void)
1247 /* We now lower VA_ARG_EXPR, and there's currently no way to attach the
1248 varargs alias set to an INDIRECT_REF (FIXME!), so we can't
1249 consistently use the varargs alias set for loads from the varargs
1250 area. So don't use it anywhere. */
1253 if (varargs_set
== -1)
1254 varargs_set
= new_alias_set ();
1260 /* Likewise, but used for the fixed portions of the frame, e.g., register
1263 static GTY(()) alias_set_type frame_set
= -1;
1266 get_frame_alias_set (void)
1268 if (frame_set
== -1)
1269 frame_set
= new_alias_set ();
1274 /* Create a new, unique base with id ID. */
1277 unique_base_value (HOST_WIDE_INT id
)
1279 return gen_rtx_ADDRESS (Pmode
, id
);
1282 /* Return true if accesses based on any other base value cannot alias
1283 those based on X. */
1286 unique_base_value_p (rtx x
)
1288 return GET_CODE (x
) == ADDRESS
&& GET_MODE (x
) == Pmode
;
1291 /* Return true if X is known to be a base value. */
1294 known_base_value_p (rtx x
)
1296 switch (GET_CODE (x
))
1303 /* Arguments may or may not be bases; we don't know for sure. */
1304 return GET_MODE (x
) != VOIDmode
;
1311 /* Inside SRC, the source of a SET, find a base address. */
1314 find_base_value (rtx src
)
1318 #if defined (FIND_BASE_TERM)
1319 /* Try machine-dependent ways to find the base term. */
1320 src
= FIND_BASE_TERM (src
);
1323 switch (GET_CODE (src
))
1330 regno
= REGNO (src
);
1331 /* At the start of a function, argument registers have known base
1332 values which may be lost later. Returning an ADDRESS
1333 expression here allows optimization based on argument values
1334 even when the argument registers are used for other purposes. */
1335 if (regno
< FIRST_PSEUDO_REGISTER
&& copying_arguments
)
1336 return new_reg_base_value
[regno
];
1338 /* If a pseudo has a known base value, return it. Do not do this
1339 for non-fixed hard regs since it can result in a circular
1340 dependency chain for registers which have values at function entry.
1342 The test above is not sufficient because the scheduler may move
1343 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
1344 if ((regno
>= FIRST_PSEUDO_REGISTER
|| fixed_regs
[regno
])
1345 && regno
< vec_safe_length (reg_base_value
))
1347 /* If we're inside init_alias_analysis, use new_reg_base_value
1348 to reduce the number of relaxation iterations. */
1349 if (new_reg_base_value
&& new_reg_base_value
[regno
]
1350 && DF_REG_DEF_COUNT (regno
) == 1)
1351 return new_reg_base_value
[regno
];
1353 if ((*reg_base_value
)[regno
])
1354 return (*reg_base_value
)[regno
];
1360 /* Check for an argument passed in memory. Only record in the
1361 copying-arguments block; it is too hard to track changes
1363 if (copying_arguments
1364 && (XEXP (src
, 0) == arg_pointer_rtx
1365 || (GET_CODE (XEXP (src
, 0)) == PLUS
1366 && XEXP (XEXP (src
, 0), 0) == arg_pointer_rtx
)))
1367 return arg_base_value
;
1371 src
= XEXP (src
, 0);
1372 if (GET_CODE (src
) != PLUS
&& GET_CODE (src
) != MINUS
)
1375 /* ... fall through ... */
1380 rtx temp
, src_0
= XEXP (src
, 0), src_1
= XEXP (src
, 1);
1382 /* If either operand is a REG that is a known pointer, then it
1384 if (REG_P (src_0
) && REG_POINTER (src_0
))
1385 return find_base_value (src_0
);
1386 if (REG_P (src_1
) && REG_POINTER (src_1
))
1387 return find_base_value (src_1
);
1389 /* If either operand is a REG, then see if we already have
1390 a known value for it. */
1393 temp
= find_base_value (src_0
);
1400 temp
= find_base_value (src_1
);
1405 /* If either base is named object or a special address
1406 (like an argument or stack reference), then use it for the
1408 if (src_0
!= 0 && known_base_value_p (src_0
))
1411 if (src_1
!= 0 && known_base_value_p (src_1
))
1414 /* Guess which operand is the base address:
1415 If either operand is a symbol, then it is the base. If
1416 either operand is a CONST_INT, then the other is the base. */
1417 if (CONST_INT_P (src_1
) || CONSTANT_P (src_0
))
1418 return find_base_value (src_0
);
1419 else if (CONST_INT_P (src_0
) || CONSTANT_P (src_1
))
1420 return find_base_value (src_1
);
1426 /* The standard form is (lo_sum reg sym) so look only at the
1428 return find_base_value (XEXP (src
, 1));
1431 /* If the second operand is constant set the base
1432 address to the first operand. */
1433 if (CONST_INT_P (XEXP (src
, 1)) && INTVAL (XEXP (src
, 1)) != 0)
1434 return find_base_value (XEXP (src
, 0));
1438 /* As we do not know which address space the pointer is referring to, we can
1439 handle this only if the target does not support different pointer or
1440 address modes depending on the address space. */
1441 if (!target_default_pointer_address_modes_p ())
1443 if (GET_MODE_SIZE (GET_MODE (src
)) < GET_MODE_SIZE (Pmode
))
1453 return find_base_value (XEXP (src
, 0));
1456 case SIGN_EXTEND
: /* used for NT/Alpha pointers */
1457 /* As we do not know which address space the pointer is referring to, we can
1458 handle this only if the target does not support different pointer or
1459 address modes depending on the address space. */
1460 if (!target_default_pointer_address_modes_p ())
1464 rtx temp
= find_base_value (XEXP (src
, 0));
1466 if (temp
!= 0 && CONSTANT_P (temp
))
1467 temp
= convert_memory_address (Pmode
, temp
);
1479 /* Called from init_alias_analysis indirectly through note_stores,
1480 or directly if DEST is a register with a REG_NOALIAS note attached.
1481 SET is null in the latter case. */
1483 /* While scanning insns to find base values, reg_seen[N] is nonzero if
1484 register N has been set in this function. */
1485 static sbitmap reg_seen
;
1488 record_set (rtx dest
, const_rtx set
, void *data ATTRIBUTE_UNUSED
)
1497 regno
= REGNO (dest
);
1499 gcc_checking_assert (regno
< reg_base_value
->length ());
1501 n
= REG_NREGS (dest
);
1506 bitmap_set_bit (reg_seen
, regno
+ n
);
1507 new_reg_base_value
[regno
+ n
] = 0;
1514 /* A CLOBBER wipes out any old value but does not prevent a previously
1515 unset register from acquiring a base address (i.e. reg_seen is not
1517 if (GET_CODE (set
) == CLOBBER
)
1519 new_reg_base_value
[regno
] = 0;
1522 src
= SET_SRC (set
);
1526 /* There's a REG_NOALIAS note against DEST. */
1527 if (bitmap_bit_p (reg_seen
, regno
))
1529 new_reg_base_value
[regno
] = 0;
1532 bitmap_set_bit (reg_seen
, regno
);
1533 new_reg_base_value
[regno
] = unique_base_value (unique_id
++);
1537 /* If this is not the first set of REGNO, see whether the new value
1538 is related to the old one. There are two cases of interest:
1540 (1) The register might be assigned an entirely new value
1541 that has the same base term as the original set.
1543 (2) The set might be a simple self-modification that
1544 cannot change REGNO's base value.
1546 If neither case holds, reject the original base value as invalid.
1547 Note that the following situation is not detected:
1549 extern int x, y; int *p = &x; p += (&y-&x);
1551 ANSI C does not allow computing the difference of addresses
1552 of distinct top level objects. */
1553 if (new_reg_base_value
[regno
] != 0
1554 && find_base_value (src
) != new_reg_base_value
[regno
])
1555 switch (GET_CODE (src
))
1559 if (XEXP (src
, 0) != dest
&& XEXP (src
, 1) != dest
)
1560 new_reg_base_value
[regno
] = 0;
1563 /* If the value we add in the PLUS is also a valid base value,
1564 this might be the actual base value, and the original value
1567 rtx other
= NULL_RTX
;
1569 if (XEXP (src
, 0) == dest
)
1570 other
= XEXP (src
, 1);
1571 else if (XEXP (src
, 1) == dest
)
1572 other
= XEXP (src
, 0);
1574 if (! other
|| find_base_value (other
))
1575 new_reg_base_value
[regno
] = 0;
1579 if (XEXP (src
, 0) != dest
|| !CONST_INT_P (XEXP (src
, 1)))
1580 new_reg_base_value
[regno
] = 0;
1583 new_reg_base_value
[regno
] = 0;
1586 /* If this is the first set of a register, record the value. */
1587 else if ((regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
1588 && ! bitmap_bit_p (reg_seen
, regno
) && new_reg_base_value
[regno
] == 0)
1589 new_reg_base_value
[regno
] = find_base_value (src
);
1591 bitmap_set_bit (reg_seen
, regno
);
1594 /* Return REG_BASE_VALUE for REGNO. Selective scheduler uses this to avoid
1595 using hard registers with non-null REG_BASE_VALUE for renaming. */
1597 get_reg_base_value (unsigned int regno
)
1599 return (*reg_base_value
)[regno
];
1602 /* If a value is known for REGNO, return it. */
1605 get_reg_known_value (unsigned int regno
)
1607 if (regno
>= FIRST_PSEUDO_REGISTER
)
1609 regno
-= FIRST_PSEUDO_REGISTER
;
1610 if (regno
< vec_safe_length (reg_known_value
))
1611 return (*reg_known_value
)[regno
];
1619 set_reg_known_value (unsigned int regno
, rtx val
)
1621 if (regno
>= FIRST_PSEUDO_REGISTER
)
1623 regno
-= FIRST_PSEUDO_REGISTER
;
1624 if (regno
< vec_safe_length (reg_known_value
))
1625 (*reg_known_value
)[regno
] = val
;
1629 /* Similarly for reg_known_equiv_p. */
1632 get_reg_known_equiv_p (unsigned int regno
)
1634 if (regno
>= FIRST_PSEUDO_REGISTER
)
1636 regno
-= FIRST_PSEUDO_REGISTER
;
1637 if (regno
< vec_safe_length (reg_known_value
))
1638 return bitmap_bit_p (reg_known_equiv_p
, regno
);
1644 set_reg_known_equiv_p (unsigned int regno
, bool val
)
1646 if (regno
>= FIRST_PSEUDO_REGISTER
)
1648 regno
-= FIRST_PSEUDO_REGISTER
;
1649 if (regno
< vec_safe_length (reg_known_value
))
1652 bitmap_set_bit (reg_known_equiv_p
, regno
);
1654 bitmap_clear_bit (reg_known_equiv_p
, regno
);
1660 /* Returns a canonical version of X, from the point of view alias
1661 analysis. (For example, if X is a MEM whose address is a register,
1662 and the register has a known value (say a SYMBOL_REF), then a MEM
1663 whose address is the SYMBOL_REF is returned.) */
1668 /* Recursively look for equivalences. */
1669 if (REG_P (x
) && REGNO (x
) >= FIRST_PSEUDO_REGISTER
)
1671 rtx t
= get_reg_known_value (REGNO (x
));
1675 return canon_rtx (t
);
1678 if (GET_CODE (x
) == PLUS
)
1680 rtx x0
= canon_rtx (XEXP (x
, 0));
1681 rtx x1
= canon_rtx (XEXP (x
, 1));
1683 if (x0
!= XEXP (x
, 0) || x1
!= XEXP (x
, 1))
1685 if (CONST_INT_P (x0
))
1686 return plus_constant (GET_MODE (x
), x1
, INTVAL (x0
));
1687 else if (CONST_INT_P (x1
))
1688 return plus_constant (GET_MODE (x
), x0
, INTVAL (x1
));
1689 return gen_rtx_PLUS (GET_MODE (x
), x0
, x1
);
1693 /* This gives us much better alias analysis when called from
1694 the loop optimizer. Note we want to leave the original
1695 MEM alone, but need to return the canonicalized MEM with
1696 all the flags with their original values. */
1698 x
= replace_equiv_address_nv (x
, canon_rtx (XEXP (x
, 0)));
1703 /* Return 1 if X and Y are identical-looking rtx's.
1704 Expect that X and Y has been already canonicalized.
1706 We use the data in reg_known_value above to see if two registers with
1707 different numbers are, in fact, equivalent. */
1710 rtx_equal_for_memref_p (const_rtx x
, const_rtx y
)
1717 if (x
== 0 && y
== 0)
1719 if (x
== 0 || y
== 0)
1725 code
= GET_CODE (x
);
1726 /* Rtx's of different codes cannot be equal. */
1727 if (code
!= GET_CODE (y
))
1730 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1731 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1733 if (GET_MODE (x
) != GET_MODE (y
))
1736 /* Some RTL can be compared without a recursive examination. */
1740 return REGNO (x
) == REGNO (y
);
1743 return LABEL_REF_LABEL (x
) == LABEL_REF_LABEL (y
);
1746 return XSTR (x
, 0) == XSTR (y
, 0);
1749 /* This is magic, don't go through canonicalization et al. */
1750 return rtx_equal_p (ENTRY_VALUE_EXP (x
), ENTRY_VALUE_EXP (y
));
1754 /* Pointer equality guarantees equality for these nodes. */
1761 /* canon_rtx knows how to handle plus. No need to canonicalize. */
1763 return ((rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0))
1764 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 1)))
1765 || (rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 1))
1766 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 0))));
1767 /* For commutative operations, the RTX match if the operand match in any
1768 order. Also handle the simple binary and unary cases without a loop. */
1769 if (COMMUTATIVE_P (x
))
1771 rtx xop0
= canon_rtx (XEXP (x
, 0));
1772 rtx yop0
= canon_rtx (XEXP (y
, 0));
1773 rtx yop1
= canon_rtx (XEXP (y
, 1));
1775 return ((rtx_equal_for_memref_p (xop0
, yop0
)
1776 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop1
))
1777 || (rtx_equal_for_memref_p (xop0
, yop1
)
1778 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop0
)));
1780 else if (NON_COMMUTATIVE_P (x
))
1782 return (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1783 canon_rtx (XEXP (y
, 0)))
1784 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)),
1785 canon_rtx (XEXP (y
, 1))));
1787 else if (UNARY_P (x
))
1788 return rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1789 canon_rtx (XEXP (y
, 0)));
1791 /* Compare the elements. If any pair of corresponding elements
1792 fail to match, return 0 for the whole things.
1794 Limit cases to types which actually appear in addresses. */
1796 fmt
= GET_RTX_FORMAT (code
);
1797 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1802 if (XINT (x
, i
) != XINT (y
, i
))
1807 /* Two vectors must have the same length. */
1808 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1811 /* And the corresponding elements must match. */
1812 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1813 if (rtx_equal_for_memref_p (canon_rtx (XVECEXP (x
, i
, j
)),
1814 canon_rtx (XVECEXP (y
, i
, j
))) == 0)
1819 if (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, i
)),
1820 canon_rtx (XEXP (y
, i
))) == 0)
1824 /* This can happen for asm operands. */
1826 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1830 /* This can happen for an asm which clobbers memory. */
1834 /* It is believed that rtx's at this level will never
1835 contain anything but integers and other rtx's,
1836 except for within LABEL_REFs and SYMBOL_REFs. */
1845 find_base_term (rtx x
)
1848 struct elt_loc_list
*l
, *f
;
1851 #if defined (FIND_BASE_TERM)
1852 /* Try machine-dependent ways to find the base term. */
1853 x
= FIND_BASE_TERM (x
);
1856 switch (GET_CODE (x
))
1859 return REG_BASE_VALUE (x
);
1862 /* As we do not know which address space the pointer is referring to, we can
1863 handle this only if the target does not support different pointer or
1864 address modes depending on the address space. */
1865 if (!target_default_pointer_address_modes_p ())
1867 if (GET_MODE_SIZE (GET_MODE (x
)) < GET_MODE_SIZE (Pmode
))
1877 return find_base_term (XEXP (x
, 0));
1880 case SIGN_EXTEND
: /* Used for Alpha/NT pointers */
1881 /* As we do not know which address space the pointer is referring to, we can
1882 handle this only if the target does not support different pointer or
1883 address modes depending on the address space. */
1884 if (!target_default_pointer_address_modes_p ())
1888 rtx temp
= find_base_term (XEXP (x
, 0));
1890 if (temp
!= 0 && CONSTANT_P (temp
))
1891 temp
= convert_memory_address (Pmode
, temp
);
1897 val
= CSELIB_VAL_PTR (x
);
1903 if (cselib_sp_based_value_p (val
))
1904 return static_reg_base_value
[STACK_POINTER_REGNUM
];
1907 /* Temporarily reset val->locs to avoid infinite recursion. */
1910 for (l
= f
; l
; l
= l
->next
)
1911 if (GET_CODE (l
->loc
) == VALUE
1912 && CSELIB_VAL_PTR (l
->loc
)->locs
1913 && !CSELIB_VAL_PTR (l
->loc
)->locs
->next
1914 && CSELIB_VAL_PTR (l
->loc
)->locs
->loc
== x
)
1916 else if ((ret
= find_base_term (l
->loc
)) != 0)
1923 /* The standard form is (lo_sum reg sym) so look only at the
1925 return find_base_term (XEXP (x
, 1));
1929 if (GET_CODE (x
) != PLUS
&& GET_CODE (x
) != MINUS
)
1935 rtx tmp1
= XEXP (x
, 0);
1936 rtx tmp2
= XEXP (x
, 1);
1938 /* This is a little bit tricky since we have to determine which of
1939 the two operands represents the real base address. Otherwise this
1940 routine may return the index register instead of the base register.
1942 That may cause us to believe no aliasing was possible, when in
1943 fact aliasing is possible.
1945 We use a few simple tests to guess the base register. Additional
1946 tests can certainly be added. For example, if one of the operands
1947 is a shift or multiply, then it must be the index register and the
1948 other operand is the base register. */
1950 if (tmp1
== pic_offset_table_rtx
&& CONSTANT_P (tmp2
))
1951 return find_base_term (tmp2
);
1953 /* If either operand is known to be a pointer, then prefer it
1954 to determine the base term. */
1955 if (REG_P (tmp1
) && REG_POINTER (tmp1
))
1957 else if (REG_P (tmp2
) && REG_POINTER (tmp2
))
1958 std::swap (tmp1
, tmp2
);
1959 /* If second argument is constant which has base term, prefer it
1960 over variable tmp1. See PR64025. */
1961 else if (CONSTANT_P (tmp2
) && !CONST_INT_P (tmp2
))
1962 std::swap (tmp1
, tmp2
);
1964 /* Go ahead and find the base term for both operands. If either base
1965 term is from a pointer or is a named object or a special address
1966 (like an argument or stack reference), then use it for the
1968 rtx base
= find_base_term (tmp1
);
1969 if (base
!= NULL_RTX
1970 && ((REG_P (tmp1
) && REG_POINTER (tmp1
))
1971 || known_base_value_p (base
)))
1973 base
= find_base_term (tmp2
);
1974 if (base
!= NULL_RTX
1975 && ((REG_P (tmp2
) && REG_POINTER (tmp2
))
1976 || known_base_value_p (base
)))
1979 /* We could not determine which of the two operands was the
1980 base register and which was the index. So we can determine
1981 nothing from the base alias check. */
1986 if (CONST_INT_P (XEXP (x
, 1)) && INTVAL (XEXP (x
, 1)) != 0)
1987 return find_base_term (XEXP (x
, 0));
1999 /* Return true if accesses to address X may alias accesses based
2000 on the stack pointer. */
2003 may_be_sp_based_p (rtx x
)
2005 rtx base
= find_base_term (x
);
2006 return !base
|| base
== static_reg_base_value
[STACK_POINTER_REGNUM
];
2009 /* Return 0 if the addresses X and Y are known to point to different
2010 objects, 1 if they might be pointers to the same object. */
2013 base_alias_check (rtx x
, rtx x_base
, rtx y
, rtx y_base
,
2014 machine_mode x_mode
, machine_mode y_mode
)
2016 /* If the address itself has no known base see if a known equivalent
2017 value has one. If either address still has no known base, nothing
2018 is known about aliasing. */
2023 if (! flag_expensive_optimizations
|| (x_c
= canon_rtx (x
)) == x
)
2026 x_base
= find_base_term (x_c
);
2034 if (! flag_expensive_optimizations
|| (y_c
= canon_rtx (y
)) == y
)
2037 y_base
= find_base_term (y_c
);
2042 /* If the base addresses are equal nothing is known about aliasing. */
2043 if (rtx_equal_p (x_base
, y_base
))
2046 /* The base addresses are different expressions. If they are not accessed
2047 via AND, there is no conflict. We can bring knowledge of object
2048 alignment into play here. For example, on alpha, "char a, b;" can
2049 alias one another, though "char a; long b;" cannot. AND addesses may
2050 implicitly alias surrounding objects; i.e. unaligned access in DImode
2051 via AND address can alias all surrounding object types except those
2052 with aligment 8 or higher. */
2053 if (GET_CODE (x
) == AND
&& GET_CODE (y
) == AND
)
2055 if (GET_CODE (x
) == AND
2056 && (!CONST_INT_P (XEXP (x
, 1))
2057 || (int) GET_MODE_UNIT_SIZE (y_mode
) < -INTVAL (XEXP (x
, 1))))
2059 if (GET_CODE (y
) == AND
2060 && (!CONST_INT_P (XEXP (y
, 1))
2061 || (int) GET_MODE_UNIT_SIZE (x_mode
) < -INTVAL (XEXP (y
, 1))))
2064 /* Differing symbols not accessed via AND never alias. */
2065 if (GET_CODE (x_base
) != ADDRESS
&& GET_CODE (y_base
) != ADDRESS
)
2068 if (unique_base_value_p (x_base
) || unique_base_value_p (y_base
))
2074 /* Return TRUE if EXPR refers to a VALUE whose uid is greater than
2078 refs_newer_value_p (const_rtx expr
, rtx v
)
2080 int minuid
= CSELIB_VAL_PTR (v
)->uid
;
2081 subrtx_iterator::array_type array
;
2082 FOR_EACH_SUBRTX (iter
, array
, expr
, NONCONST
)
2083 if (GET_CODE (*iter
) == VALUE
&& CSELIB_VAL_PTR (*iter
)->uid
> minuid
)
2088 /* Convert the address X into something we can use. This is done by returning
2089 it unchanged unless it is a value; in the latter case we call cselib to get
2090 a more useful rtx. */
2096 struct elt_loc_list
*l
;
2098 if (GET_CODE (x
) != VALUE
)
2100 v
= CSELIB_VAL_PTR (x
);
2103 bool have_equivs
= cselib_have_permanent_equivalences ();
2105 v
= canonical_cselib_val (v
);
2106 for (l
= v
->locs
; l
; l
= l
->next
)
2107 if (CONSTANT_P (l
->loc
))
2109 for (l
= v
->locs
; l
; l
= l
->next
)
2110 if (!REG_P (l
->loc
) && !MEM_P (l
->loc
)
2111 /* Avoid infinite recursion when potentially dealing with
2112 var-tracking artificial equivalences, by skipping the
2113 equivalences themselves, and not choosing expressions
2114 that refer to newer VALUEs. */
2116 || (GET_CODE (l
->loc
) != VALUE
2117 && !refs_newer_value_p (l
->loc
, x
))))
2121 for (l
= v
->locs
; l
; l
= l
->next
)
2123 || (GET_CODE (l
->loc
) != VALUE
2124 && !refs_newer_value_p (l
->loc
, x
)))
2126 /* Return the canonical value. */
2130 return v
->locs
->loc
;
2135 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
2136 where SIZE is the size in bytes of the memory reference. If ADDR
2137 is not modified by the memory reference then ADDR is returned. */
2140 addr_side_effect_eval (rtx addr
, int size
, int n_refs
)
2144 switch (GET_CODE (addr
))
2147 offset
= (n_refs
+ 1) * size
;
2150 offset
= -(n_refs
+ 1) * size
;
2153 offset
= n_refs
* size
;
2156 offset
= -n_refs
* size
;
2164 addr
= gen_rtx_PLUS (GET_MODE (addr
), XEXP (addr
, 0),
2165 gen_int_mode (offset
, GET_MODE (addr
)));
2167 addr
= XEXP (addr
, 0);
2168 addr
= canon_rtx (addr
);
2173 /* Return TRUE if an object X sized at XSIZE bytes and another object
2174 Y sized at YSIZE bytes, starting C bytes after X, may overlap. If
2175 any of the sizes is zero, assume an overlap, otherwise use the
2176 absolute value of the sizes as the actual sizes. */
2179 offset_overlap_p (HOST_WIDE_INT c
, int xsize
, int ysize
)
2181 return (xsize
== 0 || ysize
== 0
2184 : (abs (ysize
) > -c
)));
2187 /* Return one if X and Y (memory addresses) reference the
2188 same location in memory or if the references overlap.
2189 Return zero if they do not overlap, else return
2190 minus one in which case they still might reference the same location.
2192 C is an offset accumulator. When
2193 C is nonzero, we are testing aliases between X and Y + C.
2194 XSIZE is the size in bytes of the X reference,
2195 similarly YSIZE is the size in bytes for Y.
2196 Expect that canon_rtx has been already called for X and Y.
2198 If XSIZE or YSIZE is zero, we do not know the amount of memory being
2199 referenced (the reference was BLKmode), so make the most pessimistic
2202 If XSIZE or YSIZE is negative, we may access memory outside the object
2203 being referenced as a side effect. This can happen when using AND to
2204 align memory references, as is done on the Alpha.
2206 Nice to notice that varying addresses cannot conflict with fp if no
2207 local variables had their addresses taken, but that's too hard now.
2209 ??? Contrary to the tree alias oracle this does not return
2210 one for X + non-constant and Y + non-constant when X and Y are equal.
2211 If that is fixed the TBAA hack for union type-punning can be removed. */
2214 memrefs_conflict_p (int xsize
, rtx x
, int ysize
, rtx y
, HOST_WIDE_INT c
)
2216 if (GET_CODE (x
) == VALUE
)
2220 struct elt_loc_list
*l
= NULL
;
2221 if (CSELIB_VAL_PTR (x
))
2222 for (l
= canonical_cselib_val (CSELIB_VAL_PTR (x
))->locs
;
2224 if (REG_P (l
->loc
) && rtx_equal_for_memref_p (l
->loc
, y
))
2231 /* Don't call get_addr if y is the same VALUE. */
2235 if (GET_CODE (y
) == VALUE
)
2239 struct elt_loc_list
*l
= NULL
;
2240 if (CSELIB_VAL_PTR (y
))
2241 for (l
= canonical_cselib_val (CSELIB_VAL_PTR (y
))->locs
;
2243 if (REG_P (l
->loc
) && rtx_equal_for_memref_p (l
->loc
, x
))
2250 /* Don't call get_addr if x is the same VALUE. */
2254 if (GET_CODE (x
) == HIGH
)
2256 else if (GET_CODE (x
) == LO_SUM
)
2259 x
= addr_side_effect_eval (x
, abs (xsize
), 0);
2260 if (GET_CODE (y
) == HIGH
)
2262 else if (GET_CODE (y
) == LO_SUM
)
2265 y
= addr_side_effect_eval (y
, abs (ysize
), 0);
2267 if (rtx_equal_for_memref_p (x
, y
))
2269 return offset_overlap_p (c
, xsize
, ysize
);
2272 /* This code used to check for conflicts involving stack references and
2273 globals but the base address alias code now handles these cases. */
2275 if (GET_CODE (x
) == PLUS
)
2277 /* The fact that X is canonicalized means that this
2278 PLUS rtx is canonicalized. */
2279 rtx x0
= XEXP (x
, 0);
2280 rtx x1
= XEXP (x
, 1);
2282 /* However, VALUEs might end up in different positions even in
2283 canonical PLUSes. Comparing their addresses is enough. */
2285 return memrefs_conflict_p (xsize
, x1
, ysize
, const0_rtx
, c
);
2287 return memrefs_conflict_p (xsize
, x0
, ysize
, const0_rtx
, c
);
2289 if (GET_CODE (y
) == PLUS
)
2291 /* The fact that Y is canonicalized means that this
2292 PLUS rtx is canonicalized. */
2293 rtx y0
= XEXP (y
, 0);
2294 rtx y1
= XEXP (y
, 1);
2297 return memrefs_conflict_p (xsize
, x1
, ysize
, y0
, c
);
2299 return memrefs_conflict_p (xsize
, x0
, ysize
, y1
, c
);
2301 if (rtx_equal_for_memref_p (x1
, y1
))
2302 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
2303 if (rtx_equal_for_memref_p (x0
, y0
))
2304 return memrefs_conflict_p (xsize
, x1
, ysize
, y1
, c
);
2305 if (CONST_INT_P (x1
))
2307 if (CONST_INT_P (y1
))
2308 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
,
2309 c
- INTVAL (x1
) + INTVAL (y1
));
2311 return memrefs_conflict_p (xsize
, x0
, ysize
, y
,
2314 else if (CONST_INT_P (y1
))
2315 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
2319 else if (CONST_INT_P (x1
))
2320 return memrefs_conflict_p (xsize
, x0
, ysize
, y
, c
- INTVAL (x1
));
2322 else if (GET_CODE (y
) == PLUS
)
2324 /* The fact that Y is canonicalized means that this
2325 PLUS rtx is canonicalized. */
2326 rtx y0
= XEXP (y
, 0);
2327 rtx y1
= XEXP (y
, 1);
2330 return memrefs_conflict_p (xsize
, const0_rtx
, ysize
, y1
, c
);
2332 return memrefs_conflict_p (xsize
, const0_rtx
, ysize
, y0
, c
);
2334 if (CONST_INT_P (y1
))
2335 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
2340 if (GET_CODE (x
) == GET_CODE (y
))
2341 switch (GET_CODE (x
))
2345 /* Handle cases where we expect the second operands to be the
2346 same, and check only whether the first operand would conflict
2349 rtx x1
= canon_rtx (XEXP (x
, 1));
2350 rtx y1
= canon_rtx (XEXP (y
, 1));
2351 if (! rtx_equal_for_memref_p (x1
, y1
))
2353 x0
= canon_rtx (XEXP (x
, 0));
2354 y0
= canon_rtx (XEXP (y
, 0));
2355 if (rtx_equal_for_memref_p (x0
, y0
))
2356 return offset_overlap_p (c
, xsize
, ysize
);
2358 /* Can't properly adjust our sizes. */
2359 if (!CONST_INT_P (x1
))
2361 xsize
/= INTVAL (x1
);
2362 ysize
/= INTVAL (x1
);
2364 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
2371 /* Deal with alignment ANDs by adjusting offset and size so as to
2372 cover the maximum range, without taking any previously known
2373 alignment into account. Make a size negative after such an
2374 adjustments, so that, if we end up with e.g. two SYMBOL_REFs, we
2375 assume a potential overlap, because they may end up in contiguous
2376 memory locations and the stricter-alignment access may span over
2378 if (GET_CODE (x
) == AND
&& CONST_INT_P (XEXP (x
, 1)))
2380 HOST_WIDE_INT sc
= INTVAL (XEXP (x
, 1));
2381 unsigned HOST_WIDE_INT uc
= sc
;
2382 if (sc
< 0 && -uc
== (uc
& -uc
))
2389 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2393 if (GET_CODE (y
) == AND
&& CONST_INT_P (XEXP (y
, 1)))
2395 HOST_WIDE_INT sc
= INTVAL (XEXP (y
, 1));
2396 unsigned HOST_WIDE_INT uc
= sc
;
2397 if (sc
< 0 && -uc
== (uc
& -uc
))
2404 return memrefs_conflict_p (xsize
, x
,
2405 ysize
, canon_rtx (XEXP (y
, 0)), c
);
2411 if (CONST_INT_P (x
) && CONST_INT_P (y
))
2413 c
+= (INTVAL (y
) - INTVAL (x
));
2414 return offset_overlap_p (c
, xsize
, ysize
);
2417 if (GET_CODE (x
) == CONST
)
2419 if (GET_CODE (y
) == CONST
)
2420 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2421 ysize
, canon_rtx (XEXP (y
, 0)), c
);
2423 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2426 if (GET_CODE (y
) == CONST
)
2427 return memrefs_conflict_p (xsize
, x
, ysize
,
2428 canon_rtx (XEXP (y
, 0)), c
);
2430 /* Assume a potential overlap for symbolic addresses that went
2431 through alignment adjustments (i.e., that have negative
2432 sizes), because we can't know how far they are from each
2435 return (xsize
< 0 || ysize
< 0 || offset_overlap_p (c
, xsize
, ysize
));
2443 /* Functions to compute memory dependencies.
2445 Since we process the insns in execution order, we can build tables
2446 to keep track of what registers are fixed (and not aliased), what registers
2447 are varying in known ways, and what registers are varying in unknown
2450 If both memory references are volatile, then there must always be a
2451 dependence between the two references, since their order can not be
2452 changed. A volatile and non-volatile reference can be interchanged
2455 We also must allow AND addresses, because they may generate accesses
2456 outside the object being referenced. This is used to generate aligned
2457 addresses from unaligned addresses, for instance, the alpha
2458 storeqi_unaligned pattern. */
2460 /* Read dependence: X is read after read in MEM takes place. There can
2461 only be a dependence here if both reads are volatile, or if either is
2462 an explicit barrier. */
2465 read_dependence (const_rtx mem
, const_rtx x
)
2467 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2469 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2470 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2475 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
2478 decl_for_component_ref (tree x
)
2482 x
= TREE_OPERAND (x
, 0);
2484 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
2486 return x
&& DECL_P (x
) ? x
: NULL_TREE
;
2489 /* Walk up the COMPONENT_REF list in X and adjust *OFFSET to compensate
2490 for the offset of the field reference. *KNOWN_P says whether the
2494 adjust_offset_for_component_ref (tree x
, bool *known_p
,
2495 HOST_WIDE_INT
*offset
)
2501 tree xoffset
= component_ref_field_offset (x
);
2502 tree field
= TREE_OPERAND (x
, 1);
2503 if (TREE_CODE (xoffset
) != INTEGER_CST
)
2510 = (wi::to_offset (xoffset
)
2511 + wi::lrshift (wi::to_offset (DECL_FIELD_BIT_OFFSET (field
)),
2512 LOG2_BITS_PER_UNIT
));
2513 if (!wi::fits_uhwi_p (woffset
))
2518 *offset
+= woffset
.to_uhwi ();
2520 x
= TREE_OPERAND (x
, 0);
2522 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
2525 /* Return nonzero if we can determine the exprs corresponding to memrefs
2526 X and Y and they do not overlap.
2527 If LOOP_VARIANT is set, skip offset-based disambiguation */
2530 nonoverlapping_memrefs_p (const_rtx x
, const_rtx y
, bool loop_invariant
)
2532 tree exprx
= MEM_EXPR (x
), expry
= MEM_EXPR (y
);
2535 bool moffsetx_known_p
, moffsety_known_p
;
2536 HOST_WIDE_INT moffsetx
= 0, moffsety
= 0;
2537 HOST_WIDE_INT offsetx
= 0, offsety
= 0, sizex
, sizey
;
2539 /* Unless both have exprs, we can't tell anything. */
2540 if (exprx
== 0 || expry
== 0)
2543 /* For spill-slot accesses make sure we have valid offsets. */
2544 if ((exprx
== get_spill_slot_decl (false)
2545 && ! MEM_OFFSET_KNOWN_P (x
))
2546 || (expry
== get_spill_slot_decl (false)
2547 && ! MEM_OFFSET_KNOWN_P (y
)))
2550 /* If the field reference test failed, look at the DECLs involved. */
2551 moffsetx_known_p
= MEM_OFFSET_KNOWN_P (x
);
2552 if (moffsetx_known_p
)
2553 moffsetx
= MEM_OFFSET (x
);
2554 if (TREE_CODE (exprx
) == COMPONENT_REF
)
2556 tree t
= decl_for_component_ref (exprx
);
2559 adjust_offset_for_component_ref (exprx
, &moffsetx_known_p
, &moffsetx
);
2563 moffsety_known_p
= MEM_OFFSET_KNOWN_P (y
);
2564 if (moffsety_known_p
)
2565 moffsety
= MEM_OFFSET (y
);
2566 if (TREE_CODE (expry
) == COMPONENT_REF
)
2568 tree t
= decl_for_component_ref (expry
);
2571 adjust_offset_for_component_ref (expry
, &moffsety_known_p
, &moffsety
);
2575 if (! DECL_P (exprx
) || ! DECL_P (expry
))
2578 /* If we refer to different gimple registers, or one gimple register
2579 and one non-gimple-register, we know they can't overlap. First,
2580 gimple registers don't have their addresses taken. Now, there
2581 could be more than one stack slot for (different versions of) the
2582 same gimple register, but we can presumably tell they don't
2583 overlap based on offsets from stack base addresses elsewhere.
2584 It's important that we don't proceed to DECL_RTL, because gimple
2585 registers may not pass DECL_RTL_SET_P, and make_decl_rtl won't be
2586 able to do anything about them since no SSA information will have
2587 remained to guide it. */
2588 if (is_gimple_reg (exprx
) || is_gimple_reg (expry
))
2589 return exprx
!= expry
2590 || (moffsetx_known_p
&& moffsety_known_p
2591 && MEM_SIZE_KNOWN_P (x
) && MEM_SIZE_KNOWN_P (y
)
2592 && !offset_overlap_p (moffsety
- moffsetx
,
2593 MEM_SIZE (x
), MEM_SIZE (y
)));
2595 /* With invalid code we can end up storing into the constant pool.
2596 Bail out to avoid ICEing when creating RTL for this.
2597 See gfortran.dg/lto/20091028-2_0.f90. */
2598 if (TREE_CODE (exprx
) == CONST_DECL
2599 || TREE_CODE (expry
) == CONST_DECL
)
2602 rtlx
= DECL_RTL (exprx
);
2603 rtly
= DECL_RTL (expry
);
2605 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
2606 can't overlap unless they are the same because we never reuse that part
2607 of the stack frame used for locals for spilled pseudos. */
2608 if ((!MEM_P (rtlx
) || !MEM_P (rtly
))
2609 && ! rtx_equal_p (rtlx
, rtly
))
2612 /* If we have MEMs referring to different address spaces (which can
2613 potentially overlap), we cannot easily tell from the addresses
2614 whether the references overlap. */
2615 if (MEM_P (rtlx
) && MEM_P (rtly
)
2616 && MEM_ADDR_SPACE (rtlx
) != MEM_ADDR_SPACE (rtly
))
2619 /* Get the base and offsets of both decls. If either is a register, we
2620 know both are and are the same, so use that as the base. The only
2621 we can avoid overlap is if we can deduce that they are nonoverlapping
2622 pieces of that decl, which is very rare. */
2623 basex
= MEM_P (rtlx
) ? XEXP (rtlx
, 0) : rtlx
;
2624 if (GET_CODE (basex
) == PLUS
&& CONST_INT_P (XEXP (basex
, 1)))
2625 offsetx
= INTVAL (XEXP (basex
, 1)), basex
= XEXP (basex
, 0);
2627 basey
= MEM_P (rtly
) ? XEXP (rtly
, 0) : rtly
;
2628 if (GET_CODE (basey
) == PLUS
&& CONST_INT_P (XEXP (basey
, 1)))
2629 offsety
= INTVAL (XEXP (basey
, 1)), basey
= XEXP (basey
, 0);
2631 /* If the bases are different, we know they do not overlap if both
2632 are constants or if one is a constant and the other a pointer into the
2633 stack frame. Otherwise a different base means we can't tell if they
2635 if (! rtx_equal_p (basex
, basey
))
2636 return ((CONSTANT_P (basex
) && CONSTANT_P (basey
))
2637 || (CONSTANT_P (basex
) && REG_P (basey
)
2638 && REGNO_PTR_FRAME_P (REGNO (basey
)))
2639 || (CONSTANT_P (basey
) && REG_P (basex
)
2640 && REGNO_PTR_FRAME_P (REGNO (basex
))));
2642 /* Offset based disambiguation not appropriate for loop invariant */
2646 sizex
= (!MEM_P (rtlx
) ? (int) GET_MODE_SIZE (GET_MODE (rtlx
))
2647 : MEM_SIZE_KNOWN_P (rtlx
) ? MEM_SIZE (rtlx
)
2649 sizey
= (!MEM_P (rtly
) ? (int) GET_MODE_SIZE (GET_MODE (rtly
))
2650 : MEM_SIZE_KNOWN_P (rtly
) ? MEM_SIZE (rtly
)
2653 /* If we have an offset for either memref, it can update the values computed
2655 if (moffsetx_known_p
)
2656 offsetx
+= moffsetx
, sizex
-= moffsetx
;
2657 if (moffsety_known_p
)
2658 offsety
+= moffsety
, sizey
-= moffsety
;
2660 /* If a memref has both a size and an offset, we can use the smaller size.
2661 We can't do this if the offset isn't known because we must view this
2662 memref as being anywhere inside the DECL's MEM. */
2663 if (MEM_SIZE_KNOWN_P (x
) && moffsetx_known_p
)
2664 sizex
= MEM_SIZE (x
);
2665 if (MEM_SIZE_KNOWN_P (y
) && moffsety_known_p
)
2666 sizey
= MEM_SIZE (y
);
2668 /* Put the values of the memref with the lower offset in X's values. */
2669 if (offsetx
> offsety
)
2671 std::swap (offsetx
, offsety
);
2672 std::swap (sizex
, sizey
);
2675 /* If we don't know the size of the lower-offset value, we can't tell
2676 if they conflict. Otherwise, we do the test. */
2677 return sizex
>= 0 && offsety
>= offsetx
+ sizex
;
2680 /* Helper for true_dependence and canon_true_dependence.
2681 Checks for true dependence: X is read after store in MEM takes place.
2683 If MEM_CANONICALIZED is FALSE, then X_ADDR and MEM_ADDR should be
2684 NULL_RTX, and the canonical addresses of MEM and X are both computed
2685 here. If MEM_CANONICALIZED, then MEM must be already canonicalized.
2687 If X_ADDR is non-NULL, it is used in preference of XEXP (x, 0).
2689 Returns 1 if there is a true dependence, 0 otherwise. */
2692 true_dependence_1 (const_rtx mem
, machine_mode mem_mode
, rtx mem_addr
,
2693 const_rtx x
, rtx x_addr
, bool mem_canonicalized
)
2699 gcc_checking_assert (mem_canonicalized
? (mem_addr
!= NULL_RTX
)
2700 : (mem_addr
== NULL_RTX
&& x_addr
== NULL_RTX
));
2702 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2705 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2706 This is used in epilogue deallocation functions, and in cselib. */
2707 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2709 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2711 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2712 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2716 x_addr
= XEXP (x
, 0);
2717 x_addr
= get_addr (x_addr
);
2721 mem_addr
= XEXP (mem
, 0);
2722 if (mem_mode
== VOIDmode
)
2723 mem_mode
= GET_MODE (mem
);
2725 true_mem_addr
= get_addr (mem_addr
);
2727 /* Read-only memory is by definition never modified, and therefore can't
2728 conflict with anything. However, don't assume anything when AND
2729 addresses are involved and leave to the code below to determine
2730 dependence. We don't expect to find read-only set on MEM, but
2731 stupid user tricks can produce them, so don't die. */
2732 if (MEM_READONLY_P (x
)
2733 && GET_CODE (x_addr
) != AND
2734 && GET_CODE (true_mem_addr
) != AND
)
2737 /* If we have MEMs referring to different address spaces (which can
2738 potentially overlap), we cannot easily tell from the addresses
2739 whether the references overlap. */
2740 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
2743 base
= find_base_term (x_addr
);
2744 if (base
&& (GET_CODE (base
) == LABEL_REF
2745 || (GET_CODE (base
) == SYMBOL_REF
2746 && CONSTANT_POOL_ADDRESS_P (base
))))
2749 rtx mem_base
= find_base_term (true_mem_addr
);
2750 if (! base_alias_check (x_addr
, base
, true_mem_addr
, mem_base
,
2751 GET_MODE (x
), mem_mode
))
2754 x_addr
= canon_rtx (x_addr
);
2755 if (!mem_canonicalized
)
2756 mem_addr
= canon_rtx (true_mem_addr
);
2758 if ((ret
= memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
2759 SIZE_FOR_MODE (x
), x_addr
, 0)) != -1)
2762 if (mems_in_disjoint_alias_sets_p (x
, mem
))
2765 if (nonoverlapping_memrefs_p (mem
, x
, false))
2768 return rtx_refs_may_alias_p (x
, mem
, true);
2771 /* True dependence: X is read after store in MEM takes place. */
2774 true_dependence (const_rtx mem
, machine_mode mem_mode
, const_rtx x
)
2776 return true_dependence_1 (mem
, mem_mode
, NULL_RTX
,
2777 x
, NULL_RTX
, /*mem_canonicalized=*/false);
2780 /* Canonical true dependence: X is read after store in MEM takes place.
2781 Variant of true_dependence which assumes MEM has already been
2782 canonicalized (hence we no longer do that here).
2783 The mem_addr argument has been added, since true_dependence_1 computed
2784 this value prior to canonicalizing. */
2787 canon_true_dependence (const_rtx mem
, machine_mode mem_mode
, rtx mem_addr
,
2788 const_rtx x
, rtx x_addr
)
2790 return true_dependence_1 (mem
, mem_mode
, mem_addr
,
2791 x
, x_addr
, /*mem_canonicalized=*/true);
2794 /* Returns nonzero if a write to X might alias a previous read from
2795 (or, if WRITEP is true, a write to) MEM.
2796 If X_CANONCALIZED is true, then X_ADDR is the canonicalized address of X,
2797 and X_MODE the mode for that access.
2798 If MEM_CANONICALIZED is true, MEM is canonicalized. */
2801 write_dependence_p (const_rtx mem
,
2802 const_rtx x
, machine_mode x_mode
, rtx x_addr
,
2803 bool mem_canonicalized
, bool x_canonicalized
, bool writep
)
2806 rtx true_mem_addr
, true_x_addr
;
2810 gcc_checking_assert (x_canonicalized
2811 ? (x_addr
!= NULL_RTX
&& x_mode
!= VOIDmode
)
2812 : (x_addr
== NULL_RTX
&& x_mode
== VOIDmode
));
2814 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2817 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2818 This is used in epilogue deallocation functions. */
2819 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2821 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2823 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2824 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2828 x_addr
= XEXP (x
, 0);
2829 true_x_addr
= get_addr (x_addr
);
2831 mem_addr
= XEXP (mem
, 0);
2832 true_mem_addr
= get_addr (mem_addr
);
2834 /* A read from read-only memory can't conflict with read-write memory.
2835 Don't assume anything when AND addresses are involved and leave to
2836 the code below to determine dependence. */
2838 && MEM_READONLY_P (mem
)
2839 && GET_CODE (true_x_addr
) != AND
2840 && GET_CODE (true_mem_addr
) != AND
)
2843 /* If we have MEMs referring to different address spaces (which can
2844 potentially overlap), we cannot easily tell from the addresses
2845 whether the references overlap. */
2846 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
2849 base
= find_base_term (true_mem_addr
);
2852 && (GET_CODE (base
) == LABEL_REF
2853 || (GET_CODE (base
) == SYMBOL_REF
2854 && CONSTANT_POOL_ADDRESS_P (base
))))
2857 rtx x_base
= find_base_term (true_x_addr
);
2858 if (! base_alias_check (true_x_addr
, x_base
, true_mem_addr
, base
,
2859 GET_MODE (x
), GET_MODE (mem
)))
2862 if (!x_canonicalized
)
2864 x_addr
= canon_rtx (true_x_addr
);
2865 x_mode
= GET_MODE (x
);
2867 if (!mem_canonicalized
)
2868 mem_addr
= canon_rtx (true_mem_addr
);
2870 if ((ret
= memrefs_conflict_p (SIZE_FOR_MODE (mem
), mem_addr
,
2871 GET_MODE_SIZE (x_mode
), x_addr
, 0)) != -1)
2874 if (nonoverlapping_memrefs_p (x
, mem
, false))
2877 return rtx_refs_may_alias_p (x
, mem
, false);
2880 /* Anti dependence: X is written after read in MEM takes place. */
2883 anti_dependence (const_rtx mem
, const_rtx x
)
2885 return write_dependence_p (mem
, x
, VOIDmode
, NULL_RTX
,
2886 /*mem_canonicalized=*/false,
2887 /*x_canonicalized*/false, /*writep=*/false);
2890 /* Likewise, but we already have a canonicalized MEM, and X_ADDR for X.
2891 Also, consider X in X_MODE (which might be from an enclosing
2892 STRICT_LOW_PART / ZERO_EXTRACT).
2893 If MEM_CANONICALIZED is true, MEM is canonicalized. */
2896 canon_anti_dependence (const_rtx mem
, bool mem_canonicalized
,
2897 const_rtx x
, machine_mode x_mode
, rtx x_addr
)
2899 return write_dependence_p (mem
, x
, x_mode
, x_addr
,
2900 mem_canonicalized
, /*x_canonicalized=*/true,
2904 /* Output dependence: X is written after store in MEM takes place. */
2907 output_dependence (const_rtx mem
, const_rtx x
)
2909 return write_dependence_p (mem
, x
, VOIDmode
, NULL_RTX
,
2910 /*mem_canonicalized=*/false,
2911 /*x_canonicalized*/false, /*writep=*/true);
2916 /* Check whether X may be aliased with MEM. Don't do offset-based
2917 memory disambiguation & TBAA. */
2919 may_alias_p (const_rtx mem
, const_rtx x
)
2921 rtx x_addr
, mem_addr
;
2923 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2926 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2927 This is used in epilogue deallocation functions. */
2928 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2930 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2932 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2933 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2936 x_addr
= XEXP (x
, 0);
2937 x_addr
= get_addr (x_addr
);
2939 mem_addr
= XEXP (mem
, 0);
2940 mem_addr
= get_addr (mem_addr
);
2942 /* Read-only memory is by definition never modified, and therefore can't
2943 conflict with anything. However, don't assume anything when AND
2944 addresses are involved and leave to the code below to determine
2945 dependence. We don't expect to find read-only set on MEM, but
2946 stupid user tricks can produce them, so don't die. */
2947 if (MEM_READONLY_P (x
)
2948 && GET_CODE (x_addr
) != AND
2949 && GET_CODE (mem_addr
) != AND
)
2952 /* If we have MEMs referring to different address spaces (which can
2953 potentially overlap), we cannot easily tell from the addresses
2954 whether the references overlap. */
2955 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
2958 rtx x_base
= find_base_term (x_addr
);
2959 rtx mem_base
= find_base_term (mem_addr
);
2960 if (! base_alias_check (x_addr
, x_base
, mem_addr
, mem_base
,
2961 GET_MODE (x
), GET_MODE (mem_addr
)))
2964 if (nonoverlapping_memrefs_p (mem
, x
, true))
2967 /* TBAA not valid for loop_invarint */
2968 return rtx_refs_may_alias_p (x
, mem
, false);
2972 init_alias_target (void)
2976 if (!arg_base_value
)
2977 arg_base_value
= gen_rtx_ADDRESS (VOIDmode
, 0);
2979 memset (static_reg_base_value
, 0, sizeof static_reg_base_value
);
2981 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2982 /* Check whether this register can hold an incoming pointer
2983 argument. FUNCTION_ARG_REGNO_P tests outgoing register
2984 numbers, so translate if necessary due to register windows. */
2985 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i
))
2986 && HARD_REGNO_MODE_OK (i
, Pmode
))
2987 static_reg_base_value
[i
] = arg_base_value
;
2989 static_reg_base_value
[STACK_POINTER_REGNUM
]
2990 = unique_base_value (UNIQUE_BASE_VALUE_SP
);
2991 static_reg_base_value
[ARG_POINTER_REGNUM
]
2992 = unique_base_value (UNIQUE_BASE_VALUE_ARGP
);
2993 static_reg_base_value
[FRAME_POINTER_REGNUM
]
2994 = unique_base_value (UNIQUE_BASE_VALUE_FP
);
2995 if (!HARD_FRAME_POINTER_IS_FRAME_POINTER
)
2996 static_reg_base_value
[HARD_FRAME_POINTER_REGNUM
]
2997 = unique_base_value (UNIQUE_BASE_VALUE_HFP
);
3000 /* Set MEMORY_MODIFIED when X modifies DATA (that is assumed
3001 to be memory reference. */
3002 static bool memory_modified
;
3004 memory_modified_1 (rtx x
, const_rtx pat ATTRIBUTE_UNUSED
, void *data
)
3008 if (anti_dependence (x
, (const_rtx
)data
) || output_dependence (x
, (const_rtx
)data
))
3009 memory_modified
= true;
3014 /* Return true when INSN possibly modify memory contents of MEM
3015 (i.e. address can be modified). */
3017 memory_modified_in_insn_p (const_rtx mem
, const_rtx insn
)
3021 memory_modified
= false;
3022 note_stores (PATTERN (insn
), memory_modified_1
, CONST_CAST_RTX(mem
));
3023 return memory_modified
;
3026 /* Return TRUE if the destination of a set is rtx identical to
3029 set_dest_equal_p (const_rtx set
, const_rtx item
)
3031 rtx dest
= SET_DEST (set
);
3032 return rtx_equal_p (dest
, item
);
3035 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
3039 init_alias_analysis (void)
3041 unsigned int maxreg
= max_reg_num ();
3050 timevar_push (TV_ALIAS_ANALYSIS
);
3052 vec_safe_grow_cleared (reg_known_value
, maxreg
- FIRST_PSEUDO_REGISTER
);
3053 reg_known_equiv_p
= sbitmap_alloc (maxreg
- FIRST_PSEUDO_REGISTER
);
3054 bitmap_clear (reg_known_equiv_p
);
3056 /* If we have memory allocated from the previous run, use it. */
3057 if (old_reg_base_value
)
3058 reg_base_value
= old_reg_base_value
;
3061 reg_base_value
->truncate (0);
3063 vec_safe_grow_cleared (reg_base_value
, maxreg
);
3065 new_reg_base_value
= XNEWVEC (rtx
, maxreg
);
3066 reg_seen
= sbitmap_alloc (maxreg
);
3068 /* The basic idea is that each pass through this loop will use the
3069 "constant" information from the previous pass to propagate alias
3070 information through another level of assignments.
3072 The propagation is done on the CFG in reverse post-order, to propagate
3073 things forward as far as possible in each iteration.
3075 This could get expensive if the assignment chains are long. Maybe
3076 we should throttle the number of iterations, possibly based on
3077 the optimization level or flag_expensive_optimizations.
3079 We could propagate more information in the first pass by making use
3080 of DF_REG_DEF_COUNT to determine immediately that the alias information
3081 for a pseudo is "constant".
3083 A program with an uninitialized variable can cause an infinite loop
3084 here. Instead of doing a full dataflow analysis to detect such problems
3085 we just cap the number of iterations for the loop.
3087 The state of the arrays for the set chain in question does not matter
3088 since the program has undefined behavior. */
3090 rpo
= XNEWVEC (int, n_basic_blocks_for_fn (cfun
));
3091 rpo_cnt
= pre_and_rev_post_order_compute (NULL
, rpo
, false);
3093 /* The prologue/epilogue insns are not threaded onto the
3094 insn chain until after reload has completed. Thus,
3095 there is no sense wasting time checking if INSN is in
3096 the prologue/epilogue until after reload has completed. */
3097 bool could_be_prologue_epilogue
= ((targetm
.have_prologue ()
3098 || targetm
.have_epilogue ())
3099 && reload_completed
);
3104 /* Assume nothing will change this iteration of the loop. */
3107 /* We want to assign the same IDs each iteration of this loop, so
3108 start counting from one each iteration of the loop. */
3111 /* We're at the start of the function each iteration through the
3112 loop, so we're copying arguments. */
3113 copying_arguments
= true;
3115 /* Wipe the potential alias information clean for this pass. */
3116 memset (new_reg_base_value
, 0, maxreg
* sizeof (rtx
));
3118 /* Wipe the reg_seen array clean. */
3119 bitmap_clear (reg_seen
);
3121 /* Initialize the alias information for this pass. */
3122 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3123 if (static_reg_base_value
[i
])
3125 new_reg_base_value
[i
] = static_reg_base_value
[i
];
3126 bitmap_set_bit (reg_seen
, i
);
3129 /* Walk the insns adding values to the new_reg_base_value array. */
3130 for (i
= 0; i
< rpo_cnt
; i
++)
3132 basic_block bb
= BASIC_BLOCK_FOR_FN (cfun
, rpo
[i
]);
3133 FOR_BB_INSNS (bb
, insn
)
3135 if (NONDEBUG_INSN_P (insn
))
3139 if (could_be_prologue_epilogue
3140 && prologue_epilogue_contains (insn
))
3143 /* If this insn has a noalias note, process it, Otherwise,
3144 scan for sets. A simple set will have no side effects
3145 which could change the base value of any other register. */
3147 if (GET_CODE (PATTERN (insn
)) == SET
3148 && REG_NOTES (insn
) != 0
3149 && find_reg_note (insn
, REG_NOALIAS
, NULL_RTX
))
3150 record_set (SET_DEST (PATTERN (insn
)), NULL_RTX
, NULL
);
3152 note_stores (PATTERN (insn
), record_set
, NULL
);
3154 set
= single_set (insn
);
3157 && REG_P (SET_DEST (set
))
3158 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
)
3160 unsigned int regno
= REGNO (SET_DEST (set
));
3161 rtx src
= SET_SRC (set
);
3164 note
= find_reg_equal_equiv_note (insn
);
3165 if (note
&& REG_NOTE_KIND (note
) == REG_EQUAL
3166 && DF_REG_DEF_COUNT (regno
) != 1)
3169 if (note
!= NULL_RTX
3170 && GET_CODE (XEXP (note
, 0)) != EXPR_LIST
3171 && ! rtx_varies_p (XEXP (note
, 0), 1)
3172 && ! reg_overlap_mentioned_p (SET_DEST (set
),
3175 set_reg_known_value (regno
, XEXP (note
, 0));
3176 set_reg_known_equiv_p (regno
,
3177 REG_NOTE_KIND (note
) == REG_EQUIV
);
3179 else if (DF_REG_DEF_COUNT (regno
) == 1
3180 && GET_CODE (src
) == PLUS
3181 && REG_P (XEXP (src
, 0))
3182 && (t
= get_reg_known_value (REGNO (XEXP (src
, 0))))
3183 && CONST_INT_P (XEXP (src
, 1)))
3185 t
= plus_constant (GET_MODE (src
), t
,
3186 INTVAL (XEXP (src
, 1)));
3187 set_reg_known_value (regno
, t
);
3188 set_reg_known_equiv_p (regno
, false);
3190 else if (DF_REG_DEF_COUNT (regno
) == 1
3191 && ! rtx_varies_p (src
, 1))
3193 set_reg_known_value (regno
, src
);
3194 set_reg_known_equiv_p (regno
, false);
3198 else if (NOTE_P (insn
)
3199 && NOTE_KIND (insn
) == NOTE_INSN_FUNCTION_BEG
)
3200 copying_arguments
= false;
3204 /* Now propagate values from new_reg_base_value to reg_base_value. */
3205 gcc_assert (maxreg
== (unsigned int) max_reg_num ());
3207 for (ui
= 0; ui
< maxreg
; ui
++)
3209 if (new_reg_base_value
[ui
]
3210 && new_reg_base_value
[ui
] != (*reg_base_value
)[ui
]
3211 && ! rtx_equal_p (new_reg_base_value
[ui
], (*reg_base_value
)[ui
]))
3213 (*reg_base_value
)[ui
] = new_reg_base_value
[ui
];
3218 while (changed
&& ++pass
< MAX_ALIAS_LOOP_PASSES
);
3221 /* Fill in the remaining entries. */
3222 FOR_EACH_VEC_ELT (*reg_known_value
, i
, val
)
3224 int regno
= i
+ FIRST_PSEUDO_REGISTER
;
3226 set_reg_known_value (regno
, regno_reg_rtx
[regno
]);
3230 free (new_reg_base_value
);
3231 new_reg_base_value
= 0;
3232 sbitmap_free (reg_seen
);
3234 timevar_pop (TV_ALIAS_ANALYSIS
);
3237 /* Equate REG_BASE_VALUE (reg1) to REG_BASE_VALUE (reg2).
3238 Special API for var-tracking pass purposes. */
3241 vt_equate_reg_base_value (const_rtx reg1
, const_rtx reg2
)
3243 (*reg_base_value
)[REGNO (reg1
)] = REG_BASE_VALUE (reg2
);
3247 end_alias_analysis (void)
3249 old_reg_base_value
= reg_base_value
;
3250 vec_free (reg_known_value
);
3251 sbitmap_free (reg_known_equiv_p
);
3255 dump_alias_stats_in_alias_c (FILE *s
)
3257 fprintf (s
, " TBAA oracle: %llu disambiguations %llu queries\n"
3258 " %llu are in alias set 0\n"
3259 " %llu queries asked about the same object\n"
3260 " %llu queries asked about the same alias set\n"
3261 " %llu access volatile\n"
3262 " %llu are dependent in the DAG\n"
3263 " %llu are aritificially in conflict with void *\n",
3264 alias_stats
.num_disambiguated
,
3265 alias_stats
.num_alias_zero
+ alias_stats
.num_same_alias_set
3266 + alias_stats
.num_same_objects
+ alias_stats
.num_volatile
3267 + alias_stats
.num_dag
+ alias_stats
.num_disambiguated
3268 + alias_stats
.num_universal
,
3269 alias_stats
.num_alias_zero
, alias_stats
.num_same_alias_set
,
3270 alias_stats
.num_same_objects
, alias_stats
.num_volatile
,
3271 alias_stats
.num_dag
, alias_stats
.num_universal
);
3273 #include "gt-alias.h"