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. This is easy
873 to do, because the code bellow ignore canonical types on these anyway.
874 This is important for LTO, where TYPE_CANONICAL for pointers can not
875 be meaningfuly computed by the frotnend. */
876 if (!POINTER_TYPE_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 if (TYPE_ALIAS_SET_KNOWN_P (t
))
892 return TYPE_ALIAS_SET (t
);
894 /* We don't want to set TYPE_ALIAS_SET for incomplete types. */
895 if (!COMPLETE_TYPE_P (t
))
897 /* For arrays with unknown size the conservative answer is the
898 alias set of the element type. */
899 if (TREE_CODE (t
) == ARRAY_TYPE
)
900 return get_alias_set (TREE_TYPE (t
));
902 /* But return zero as a conservative answer for incomplete types. */
906 /* See if the language has special handling for this type. */
907 set
= lang_hooks
.get_alias_set (t
);
911 /* There are no objects of FUNCTION_TYPE, so there's no point in
912 using up an alias set for them. (There are, of course, pointers
913 and references to functions, but that's different.) */
914 else if (TREE_CODE (t
) == FUNCTION_TYPE
|| TREE_CODE (t
) == METHOD_TYPE
)
917 /* Unless the language specifies otherwise, let vector types alias
918 their components. This avoids some nasty type punning issues in
919 normal usage. And indeed lets vectors be treated more like an
921 else if (TREE_CODE (t
) == VECTOR_TYPE
)
922 set
= get_alias_set (TREE_TYPE (t
));
924 /* Unless the language specifies otherwise, treat array types the
925 same as their components. This avoids the asymmetry we get
926 through recording the components. Consider accessing a
927 character(kind=1) through a reference to a character(kind=1)[1:1].
928 Or consider if we want to assign integer(kind=4)[0:D.1387] and
929 integer(kind=4)[4] the same alias set or not.
930 Just be pragmatic here and make sure the array and its element
931 type get the same alias set assigned. */
932 else if (TREE_CODE (t
) == ARRAY_TYPE
&& !TYPE_NONALIASED_COMPONENT (t
))
933 set
= get_alias_set (TREE_TYPE (t
));
935 /* From the former common C and C++ langhook implementation:
937 Unfortunately, there is no canonical form of a pointer type.
938 In particular, if we have `typedef int I', then `int *', and
939 `I *' are different types. So, we have to pick a canonical
940 representative. We do this below.
942 Technically, this approach is actually more conservative that
943 it needs to be. In particular, `const int *' and `int *'
944 should be in different alias sets, according to the C and C++
945 standard, since their types are not the same, and so,
946 technically, an `int **' and `const int **' cannot point at
949 But, the standard is wrong. In particular, this code is
954 const int* const* cipp = ipp;
955 And, it doesn't make sense for that to be legal unless you
956 can dereference IPP and CIPP. So, we ignore cv-qualifiers on
957 the pointed-to types. This issue has been reported to the
960 For this reason go to canonical type of the unqalified pointer type.
961 Until GCC 6 this code set all pointers sets to have alias set of
962 ptr_type_node but that is a bad idea, because it prevents disabiguations
963 in between pointers. For Firefox this accounts about 20% of all
964 disambiguations in the program. */
965 else if (POINTER_TYPE_P (t
) && t
!= ptr_type_node
)
968 auto_vec
<bool, 8> reference
;
970 /* Unnest all pointers and references.
971 We also want to make pointer to array/vector equivalent to pointer to
972 its element (see the reasoning above). Skip all those types, too. */
973 for (p
= t
; POINTER_TYPE_P (p
)
974 || (TREE_CODE (p
) == ARRAY_TYPE
&& !TYPE_NONALIASED_COMPONENT (p
))
975 || TREE_CODE (p
) == VECTOR_TYPE
;
978 if (TREE_CODE (p
) == REFERENCE_TYPE
)
979 /* In LTO we want languages that use references to be compatible
980 with languages that use pointers. */
981 reference
.safe_push (true && !in_lto_p
);
982 if (TREE_CODE (p
) == POINTER_TYPE
)
983 reference
.safe_push (false);
985 p
= TYPE_MAIN_VARIANT (p
);
987 /* Make void * compatible with char * and also void **.
988 Programs are commonly violating TBAA by this.
990 We also make void * to conflict with every pointer
991 (see record_component_aliases) and thus it is safe it to use it for
992 pointers to types with TYPE_STRUCTURAL_EQUALITY_P. */
993 if (TREE_CODE (p
) == VOID_TYPE
|| TYPE_STRUCTURAL_EQUALITY_P (p
))
994 set
= get_alias_set (ptr_type_node
);
997 /* Rebuild pointer type starting from canonical types using
998 unqualified pointers and references only. This way all such
999 pointers will have the same alias set and will conflict with
1002 Most of time we already have pointers or references of a given type.
1003 If not we build new one just to be sure that if someone later
1004 (probably only middle-end can, as we should assign all alias
1005 classes only after finishing translation unit) builds the pointer
1006 type, the canonical type will match. */
1007 p
= TYPE_CANONICAL (p
);
1008 while (!reference
.is_empty ())
1010 if (reference
.pop ())
1011 p
= build_reference_type (p
);
1013 p
= build_pointer_type (p
);
1014 gcc_checking_assert (p
== TYPE_MAIN_VARIANT (p
));
1015 /* build_pointer_type should always return the canonical type.
1016 For LTO TYPE_CANOINCAL may be NULL, because we do not compute
1017 them. Be sure that frontends do not glob canonical types of
1018 pointers in unexpected way and that p == TYPE_CANONICAL (p)
1019 in all other cases. */
1020 gcc_checking_assert (!TYPE_CANONICAL (p
)
1021 || p
== TYPE_CANONICAL (p
));
1024 /* Assign the alias set to both p and t.
1025 We can not call get_alias_set (p) here as that would trigger
1026 infinite recursion when p == t. In other cases it would just
1027 trigger unnecesary legwork of rebuilding the pointer again. */
1028 if (TYPE_ALIAS_SET_KNOWN_P (p
))
1029 set
= TYPE_ALIAS_SET (p
);
1032 set
= new_alias_set ();
1033 TYPE_ALIAS_SET (p
) = set
;
1037 /* Alias set of ptr_type_node is special and serve as universal pointer which
1038 is TBAA compatible with every other pointer type. Be sure we have the
1039 alias set built even for LTO which otherwise keeps all TYPE_CANONICAL
1040 of pointer types NULL. */
1041 else if (t
== ptr_type_node
)
1042 set
= new_alias_set ();
1044 /* Otherwise make a new alias set for this type. */
1047 /* Each canonical type gets its own alias set, so canonical types
1048 shouldn't form a tree. It doesn't really matter for types
1049 we handle specially above, so only check it where it possibly
1050 would result in a bogus alias set. */
1051 gcc_checking_assert (TYPE_CANONICAL (t
) == t
);
1053 set
= new_alias_set ();
1056 TYPE_ALIAS_SET (t
) = set
;
1058 /* If this is an aggregate type or a complex type, we must record any
1059 component aliasing information. */
1060 if (AGGREGATE_TYPE_P (t
) || TREE_CODE (t
) == COMPLEX_TYPE
)
1061 record_component_aliases (t
);
1063 /* We treat pointer types specially in alias_set_subset_of. */
1064 if (POINTER_TYPE_P (t
) && set
)
1066 alias_set_entry
*ase
= get_alias_set_entry (set
);
1068 ase
= init_alias_set_entry (set
);
1069 ase
->is_pointer
= true;
1070 ase
->has_pointer
= true;
1076 /* Return a brand-new alias set. */
1079 new_alias_set (void)
1081 if (flag_strict_aliasing
)
1083 if (alias_sets
== 0)
1084 vec_safe_push (alias_sets
, (alias_set_entry
*) NULL
);
1085 vec_safe_push (alias_sets
, (alias_set_entry
*) NULL
);
1086 return alias_sets
->length () - 1;
1092 /* Indicate that things in SUBSET can alias things in SUPERSET, but that
1093 not everything that aliases SUPERSET also aliases SUBSET. For example,
1094 in C, a store to an `int' can alias a load of a structure containing an
1095 `int', and vice versa. But it can't alias a load of a 'double' member
1096 of the same structure. Here, the structure would be the SUPERSET and
1097 `int' the SUBSET. This relationship is also described in the comment at
1098 the beginning of this file.
1100 This function should be called only once per SUPERSET/SUBSET pair.
1102 It is illegal for SUPERSET to be zero; everything is implicitly a
1103 subset of alias set zero. */
1106 record_alias_subset (alias_set_type superset
, alias_set_type subset
)
1108 alias_set_entry
*superset_entry
;
1109 alias_set_entry
*subset_entry
;
1111 /* It is possible in complex type situations for both sets to be the same,
1112 in which case we can ignore this operation. */
1113 if (superset
== subset
)
1116 gcc_assert (superset
);
1118 superset_entry
= get_alias_set_entry (superset
);
1119 if (superset_entry
== 0)
1121 /* Create an entry for the SUPERSET, so that we have a place to
1122 attach the SUBSET. */
1123 superset_entry
= init_alias_set_entry (superset
);
1127 superset_entry
->has_zero_child
= 1;
1130 subset_entry
= get_alias_set_entry (subset
);
1131 if (!superset_entry
->children
)
1132 superset_entry
->children
1133 = hash_map
<alias_set_hash
, int>::create_ggc (64);
1134 /* If there is an entry for the subset, enter all of its children
1135 (if they are not already present) as children of the SUPERSET. */
1138 if (subset_entry
->has_zero_child
)
1139 superset_entry
->has_zero_child
= true;
1140 if (subset_entry
->has_pointer
)
1141 superset_entry
->has_pointer
= true;
1143 if (subset_entry
->children
)
1145 hash_map
<alias_set_hash
, int>::iterator iter
1146 = subset_entry
->children
->begin ();
1147 for (; iter
!= subset_entry
->children
->end (); ++iter
)
1148 superset_entry
->children
->put ((*iter
).first
, (*iter
).second
);
1152 /* Enter the SUBSET itself as a child of the SUPERSET. */
1153 superset_entry
->children
->put (subset
, 0);
1157 /* Record that component types of TYPE, if any, are part of that type for
1158 aliasing purposes. For record types, we only record component types
1159 for fields that are not marked non-addressable. For array types, we
1160 only record the component type if it is not marked non-aliased. */
1163 record_component_aliases (tree type
)
1165 alias_set_type superset
= get_alias_set (type
);
1171 switch (TREE_CODE (type
))
1175 case QUAL_UNION_TYPE
:
1176 for (field
= TYPE_FIELDS (type
); field
!= 0; field
= DECL_CHAIN (field
))
1177 if (TREE_CODE (field
) == FIELD_DECL
&& !DECL_NONADDRESSABLE_P (field
))
1179 /* LTO type merging does not make any difference between
1180 component pointer types. We may have
1182 struct foo {int *a;};
1184 as TYPE_CANONICAL of
1186 struct bar {float *a;};
1188 Because accesses to int * and float * do not alias, we would get
1189 false negative when accessing the same memory location by
1190 float ** and bar *. We thus record the canonical type as:
1194 void * is special cased and works as a universal pointer type.
1195 Accesses to it conflicts with accesses to any other pointer
1197 tree t
= TREE_TYPE (field
);
1200 /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their
1201 element type and that type has to be normalized to void *,
1202 too, in the case it is a pointer. */
1203 while ((TREE_CODE (t
) == ARRAY_TYPE
1204 && (!COMPLETE_TYPE_P (t
)
1205 || TYPE_NONALIASED_COMPONENT (t
)))
1206 || TREE_CODE (t
) == VECTOR_TYPE
)
1208 if (POINTER_TYPE_P (t
))
1212 record_alias_subset (superset
, get_alias_set (t
));
1217 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
1220 /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their
1228 /* Allocate an alias set for use in storing and reading from the varargs
1231 static GTY(()) alias_set_type varargs_set
= -1;
1234 get_varargs_alias_set (void)
1237 /* We now lower VA_ARG_EXPR, and there's currently no way to attach the
1238 varargs alias set to an INDIRECT_REF (FIXME!), so we can't
1239 consistently use the varargs alias set for loads from the varargs
1240 area. So don't use it anywhere. */
1243 if (varargs_set
== -1)
1244 varargs_set
= new_alias_set ();
1250 /* Likewise, but used for the fixed portions of the frame, e.g., register
1253 static GTY(()) alias_set_type frame_set
= -1;
1256 get_frame_alias_set (void)
1258 if (frame_set
== -1)
1259 frame_set
= new_alias_set ();
1264 /* Create a new, unique base with id ID. */
1267 unique_base_value (HOST_WIDE_INT id
)
1269 return gen_rtx_ADDRESS (Pmode
, id
);
1272 /* Return true if accesses based on any other base value cannot alias
1273 those based on X. */
1276 unique_base_value_p (rtx x
)
1278 return GET_CODE (x
) == ADDRESS
&& GET_MODE (x
) == Pmode
;
1281 /* Return true if X is known to be a base value. */
1284 known_base_value_p (rtx x
)
1286 switch (GET_CODE (x
))
1293 /* Arguments may or may not be bases; we don't know for sure. */
1294 return GET_MODE (x
) != VOIDmode
;
1301 /* Inside SRC, the source of a SET, find a base address. */
1304 find_base_value (rtx src
)
1308 #if defined (FIND_BASE_TERM)
1309 /* Try machine-dependent ways to find the base term. */
1310 src
= FIND_BASE_TERM (src
);
1313 switch (GET_CODE (src
))
1320 regno
= REGNO (src
);
1321 /* At the start of a function, argument registers have known base
1322 values which may be lost later. Returning an ADDRESS
1323 expression here allows optimization based on argument values
1324 even when the argument registers are used for other purposes. */
1325 if (regno
< FIRST_PSEUDO_REGISTER
&& copying_arguments
)
1326 return new_reg_base_value
[regno
];
1328 /* If a pseudo has a known base value, return it. Do not do this
1329 for non-fixed hard regs since it can result in a circular
1330 dependency chain for registers which have values at function entry.
1332 The test above is not sufficient because the scheduler may move
1333 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
1334 if ((regno
>= FIRST_PSEUDO_REGISTER
|| fixed_regs
[regno
])
1335 && regno
< vec_safe_length (reg_base_value
))
1337 /* If we're inside init_alias_analysis, use new_reg_base_value
1338 to reduce the number of relaxation iterations. */
1339 if (new_reg_base_value
&& new_reg_base_value
[regno
]
1340 && DF_REG_DEF_COUNT (regno
) == 1)
1341 return new_reg_base_value
[regno
];
1343 if ((*reg_base_value
)[regno
])
1344 return (*reg_base_value
)[regno
];
1350 /* Check for an argument passed in memory. Only record in the
1351 copying-arguments block; it is too hard to track changes
1353 if (copying_arguments
1354 && (XEXP (src
, 0) == arg_pointer_rtx
1355 || (GET_CODE (XEXP (src
, 0)) == PLUS
1356 && XEXP (XEXP (src
, 0), 0) == arg_pointer_rtx
)))
1357 return arg_base_value
;
1361 src
= XEXP (src
, 0);
1362 if (GET_CODE (src
) != PLUS
&& GET_CODE (src
) != MINUS
)
1365 /* ... fall through ... */
1370 rtx temp
, src_0
= XEXP (src
, 0), src_1
= XEXP (src
, 1);
1372 /* If either operand is a REG that is a known pointer, then it
1374 if (REG_P (src_0
) && REG_POINTER (src_0
))
1375 return find_base_value (src_0
);
1376 if (REG_P (src_1
) && REG_POINTER (src_1
))
1377 return find_base_value (src_1
);
1379 /* If either operand is a REG, then see if we already have
1380 a known value for it. */
1383 temp
= find_base_value (src_0
);
1390 temp
= find_base_value (src_1
);
1395 /* If either base is named object or a special address
1396 (like an argument or stack reference), then use it for the
1398 if (src_0
!= 0 && known_base_value_p (src_0
))
1401 if (src_1
!= 0 && known_base_value_p (src_1
))
1404 /* Guess which operand is the base address:
1405 If either operand is a symbol, then it is the base. If
1406 either operand is a CONST_INT, then the other is the base. */
1407 if (CONST_INT_P (src_1
) || CONSTANT_P (src_0
))
1408 return find_base_value (src_0
);
1409 else if (CONST_INT_P (src_0
) || CONSTANT_P (src_1
))
1410 return find_base_value (src_1
);
1416 /* The standard form is (lo_sum reg sym) so look only at the
1418 return find_base_value (XEXP (src
, 1));
1421 /* If the second operand is constant set the base
1422 address to the first operand. */
1423 if (CONST_INT_P (XEXP (src
, 1)) && INTVAL (XEXP (src
, 1)) != 0)
1424 return find_base_value (XEXP (src
, 0));
1428 /* As we do not know which address space the pointer is referring to, we can
1429 handle this only if the target does not support different pointer or
1430 address modes depending on the address space. */
1431 if (!target_default_pointer_address_modes_p ())
1433 if (GET_MODE_SIZE (GET_MODE (src
)) < GET_MODE_SIZE (Pmode
))
1443 return find_base_value (XEXP (src
, 0));
1446 case SIGN_EXTEND
: /* used for NT/Alpha pointers */
1447 /* As we do not know which address space the pointer is referring to, we can
1448 handle this only if the target does not support different pointer or
1449 address modes depending on the address space. */
1450 if (!target_default_pointer_address_modes_p ())
1454 rtx temp
= find_base_value (XEXP (src
, 0));
1456 if (temp
!= 0 && CONSTANT_P (temp
))
1457 temp
= convert_memory_address (Pmode
, temp
);
1469 /* Called from init_alias_analysis indirectly through note_stores,
1470 or directly if DEST is a register with a REG_NOALIAS note attached.
1471 SET is null in the latter case. */
1473 /* While scanning insns to find base values, reg_seen[N] is nonzero if
1474 register N has been set in this function. */
1475 static sbitmap reg_seen
;
1478 record_set (rtx dest
, const_rtx set
, void *data ATTRIBUTE_UNUSED
)
1487 regno
= REGNO (dest
);
1489 gcc_checking_assert (regno
< reg_base_value
->length ());
1491 n
= REG_NREGS (dest
);
1496 bitmap_set_bit (reg_seen
, regno
+ n
);
1497 new_reg_base_value
[regno
+ n
] = 0;
1504 /* A CLOBBER wipes out any old value but does not prevent a previously
1505 unset register from acquiring a base address (i.e. reg_seen is not
1507 if (GET_CODE (set
) == CLOBBER
)
1509 new_reg_base_value
[regno
] = 0;
1512 src
= SET_SRC (set
);
1516 /* There's a REG_NOALIAS note against DEST. */
1517 if (bitmap_bit_p (reg_seen
, regno
))
1519 new_reg_base_value
[regno
] = 0;
1522 bitmap_set_bit (reg_seen
, regno
);
1523 new_reg_base_value
[regno
] = unique_base_value (unique_id
++);
1527 /* If this is not the first set of REGNO, see whether the new value
1528 is related to the old one. There are two cases of interest:
1530 (1) The register might be assigned an entirely new value
1531 that has the same base term as the original set.
1533 (2) The set might be a simple self-modification that
1534 cannot change REGNO's base value.
1536 If neither case holds, reject the original base value as invalid.
1537 Note that the following situation is not detected:
1539 extern int x, y; int *p = &x; p += (&y-&x);
1541 ANSI C does not allow computing the difference of addresses
1542 of distinct top level objects. */
1543 if (new_reg_base_value
[regno
] != 0
1544 && find_base_value (src
) != new_reg_base_value
[regno
])
1545 switch (GET_CODE (src
))
1549 if (XEXP (src
, 0) != dest
&& XEXP (src
, 1) != dest
)
1550 new_reg_base_value
[regno
] = 0;
1553 /* If the value we add in the PLUS is also a valid base value,
1554 this might be the actual base value, and the original value
1557 rtx other
= NULL_RTX
;
1559 if (XEXP (src
, 0) == dest
)
1560 other
= XEXP (src
, 1);
1561 else if (XEXP (src
, 1) == dest
)
1562 other
= XEXP (src
, 0);
1564 if (! other
|| find_base_value (other
))
1565 new_reg_base_value
[regno
] = 0;
1569 if (XEXP (src
, 0) != dest
|| !CONST_INT_P (XEXP (src
, 1)))
1570 new_reg_base_value
[regno
] = 0;
1573 new_reg_base_value
[regno
] = 0;
1576 /* If this is the first set of a register, record the value. */
1577 else if ((regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
1578 && ! bitmap_bit_p (reg_seen
, regno
) && new_reg_base_value
[regno
] == 0)
1579 new_reg_base_value
[regno
] = find_base_value (src
);
1581 bitmap_set_bit (reg_seen
, regno
);
1584 /* Return REG_BASE_VALUE for REGNO. Selective scheduler uses this to avoid
1585 using hard registers with non-null REG_BASE_VALUE for renaming. */
1587 get_reg_base_value (unsigned int regno
)
1589 return (*reg_base_value
)[regno
];
1592 /* If a value is known for REGNO, return it. */
1595 get_reg_known_value (unsigned int regno
)
1597 if (regno
>= FIRST_PSEUDO_REGISTER
)
1599 regno
-= FIRST_PSEUDO_REGISTER
;
1600 if (regno
< vec_safe_length (reg_known_value
))
1601 return (*reg_known_value
)[regno
];
1609 set_reg_known_value (unsigned int regno
, rtx val
)
1611 if (regno
>= FIRST_PSEUDO_REGISTER
)
1613 regno
-= FIRST_PSEUDO_REGISTER
;
1614 if (regno
< vec_safe_length (reg_known_value
))
1615 (*reg_known_value
)[regno
] = val
;
1619 /* Similarly for reg_known_equiv_p. */
1622 get_reg_known_equiv_p (unsigned int regno
)
1624 if (regno
>= FIRST_PSEUDO_REGISTER
)
1626 regno
-= FIRST_PSEUDO_REGISTER
;
1627 if (regno
< vec_safe_length (reg_known_value
))
1628 return bitmap_bit_p (reg_known_equiv_p
, regno
);
1634 set_reg_known_equiv_p (unsigned int regno
, bool val
)
1636 if (regno
>= FIRST_PSEUDO_REGISTER
)
1638 regno
-= FIRST_PSEUDO_REGISTER
;
1639 if (regno
< vec_safe_length (reg_known_value
))
1642 bitmap_set_bit (reg_known_equiv_p
, regno
);
1644 bitmap_clear_bit (reg_known_equiv_p
, regno
);
1650 /* Returns a canonical version of X, from the point of view alias
1651 analysis. (For example, if X is a MEM whose address is a register,
1652 and the register has a known value (say a SYMBOL_REF), then a MEM
1653 whose address is the SYMBOL_REF is returned.) */
1658 /* Recursively look for equivalences. */
1659 if (REG_P (x
) && REGNO (x
) >= FIRST_PSEUDO_REGISTER
)
1661 rtx t
= get_reg_known_value (REGNO (x
));
1665 return canon_rtx (t
);
1668 if (GET_CODE (x
) == PLUS
)
1670 rtx x0
= canon_rtx (XEXP (x
, 0));
1671 rtx x1
= canon_rtx (XEXP (x
, 1));
1673 if (x0
!= XEXP (x
, 0) || x1
!= XEXP (x
, 1))
1675 if (CONST_INT_P (x0
))
1676 return plus_constant (GET_MODE (x
), x1
, INTVAL (x0
));
1677 else if (CONST_INT_P (x1
))
1678 return plus_constant (GET_MODE (x
), x0
, INTVAL (x1
));
1679 return gen_rtx_PLUS (GET_MODE (x
), x0
, x1
);
1683 /* This gives us much better alias analysis when called from
1684 the loop optimizer. Note we want to leave the original
1685 MEM alone, but need to return the canonicalized MEM with
1686 all the flags with their original values. */
1688 x
= replace_equiv_address_nv (x
, canon_rtx (XEXP (x
, 0)));
1693 /* Return 1 if X and Y are identical-looking rtx's.
1694 Expect that X and Y has been already canonicalized.
1696 We use the data in reg_known_value above to see if two registers with
1697 different numbers are, in fact, equivalent. */
1700 rtx_equal_for_memref_p (const_rtx x
, const_rtx y
)
1707 if (x
== 0 && y
== 0)
1709 if (x
== 0 || y
== 0)
1715 code
= GET_CODE (x
);
1716 /* Rtx's of different codes cannot be equal. */
1717 if (code
!= GET_CODE (y
))
1720 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1721 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1723 if (GET_MODE (x
) != GET_MODE (y
))
1726 /* Some RTL can be compared without a recursive examination. */
1730 return REGNO (x
) == REGNO (y
);
1733 return LABEL_REF_LABEL (x
) == LABEL_REF_LABEL (y
);
1736 return XSTR (x
, 0) == XSTR (y
, 0);
1739 /* This is magic, don't go through canonicalization et al. */
1740 return rtx_equal_p (ENTRY_VALUE_EXP (x
), ENTRY_VALUE_EXP (y
));
1744 /* Pointer equality guarantees equality for these nodes. */
1751 /* canon_rtx knows how to handle plus. No need to canonicalize. */
1753 return ((rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0))
1754 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 1)))
1755 || (rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 1))
1756 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 0))));
1757 /* For commutative operations, the RTX match if the operand match in any
1758 order. Also handle the simple binary and unary cases without a loop. */
1759 if (COMMUTATIVE_P (x
))
1761 rtx xop0
= canon_rtx (XEXP (x
, 0));
1762 rtx yop0
= canon_rtx (XEXP (y
, 0));
1763 rtx yop1
= canon_rtx (XEXP (y
, 1));
1765 return ((rtx_equal_for_memref_p (xop0
, yop0
)
1766 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop1
))
1767 || (rtx_equal_for_memref_p (xop0
, yop1
)
1768 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop0
)));
1770 else if (NON_COMMUTATIVE_P (x
))
1772 return (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1773 canon_rtx (XEXP (y
, 0)))
1774 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)),
1775 canon_rtx (XEXP (y
, 1))));
1777 else if (UNARY_P (x
))
1778 return rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1779 canon_rtx (XEXP (y
, 0)));
1781 /* Compare the elements. If any pair of corresponding elements
1782 fail to match, return 0 for the whole things.
1784 Limit cases to types which actually appear in addresses. */
1786 fmt
= GET_RTX_FORMAT (code
);
1787 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1792 if (XINT (x
, i
) != XINT (y
, i
))
1797 /* Two vectors must have the same length. */
1798 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1801 /* And the corresponding elements must match. */
1802 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1803 if (rtx_equal_for_memref_p (canon_rtx (XVECEXP (x
, i
, j
)),
1804 canon_rtx (XVECEXP (y
, i
, j
))) == 0)
1809 if (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, i
)),
1810 canon_rtx (XEXP (y
, i
))) == 0)
1814 /* This can happen for asm operands. */
1816 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1820 /* This can happen for an asm which clobbers memory. */
1824 /* It is believed that rtx's at this level will never
1825 contain anything but integers and other rtx's,
1826 except for within LABEL_REFs and SYMBOL_REFs. */
1835 find_base_term (rtx x
)
1838 struct elt_loc_list
*l
, *f
;
1841 #if defined (FIND_BASE_TERM)
1842 /* Try machine-dependent ways to find the base term. */
1843 x
= FIND_BASE_TERM (x
);
1846 switch (GET_CODE (x
))
1849 return REG_BASE_VALUE (x
);
1852 /* As we do not know which address space the pointer is referring to, we can
1853 handle this only if the target does not support different pointer or
1854 address modes depending on the address space. */
1855 if (!target_default_pointer_address_modes_p ())
1857 if (GET_MODE_SIZE (GET_MODE (x
)) < GET_MODE_SIZE (Pmode
))
1867 return find_base_term (XEXP (x
, 0));
1870 case SIGN_EXTEND
: /* Used for Alpha/NT pointers */
1871 /* As we do not know which address space the pointer is referring to, we can
1872 handle this only if the target does not support different pointer or
1873 address modes depending on the address space. */
1874 if (!target_default_pointer_address_modes_p ())
1878 rtx temp
= find_base_term (XEXP (x
, 0));
1880 if (temp
!= 0 && CONSTANT_P (temp
))
1881 temp
= convert_memory_address (Pmode
, temp
);
1887 val
= CSELIB_VAL_PTR (x
);
1893 if (cselib_sp_based_value_p (val
))
1894 return static_reg_base_value
[STACK_POINTER_REGNUM
];
1897 /* Temporarily reset val->locs to avoid infinite recursion. */
1900 for (l
= f
; l
; l
= l
->next
)
1901 if (GET_CODE (l
->loc
) == VALUE
1902 && CSELIB_VAL_PTR (l
->loc
)->locs
1903 && !CSELIB_VAL_PTR (l
->loc
)->locs
->next
1904 && CSELIB_VAL_PTR (l
->loc
)->locs
->loc
== x
)
1906 else if ((ret
= find_base_term (l
->loc
)) != 0)
1913 /* The standard form is (lo_sum reg sym) so look only at the
1915 return find_base_term (XEXP (x
, 1));
1919 if (GET_CODE (x
) != PLUS
&& GET_CODE (x
) != MINUS
)
1925 rtx tmp1
= XEXP (x
, 0);
1926 rtx tmp2
= XEXP (x
, 1);
1928 /* This is a little bit tricky since we have to determine which of
1929 the two operands represents the real base address. Otherwise this
1930 routine may return the index register instead of the base register.
1932 That may cause us to believe no aliasing was possible, when in
1933 fact aliasing is possible.
1935 We use a few simple tests to guess the base register. Additional
1936 tests can certainly be added. For example, if one of the operands
1937 is a shift or multiply, then it must be the index register and the
1938 other operand is the base register. */
1940 if (tmp1
== pic_offset_table_rtx
&& CONSTANT_P (tmp2
))
1941 return find_base_term (tmp2
);
1943 /* If either operand is known to be a pointer, then prefer it
1944 to determine the base term. */
1945 if (REG_P (tmp1
) && REG_POINTER (tmp1
))
1947 else if (REG_P (tmp2
) && REG_POINTER (tmp2
))
1948 std::swap (tmp1
, tmp2
);
1949 /* If second argument is constant which has base term, prefer it
1950 over variable tmp1. See PR64025. */
1951 else if (CONSTANT_P (tmp2
) && !CONST_INT_P (tmp2
))
1952 std::swap (tmp1
, tmp2
);
1954 /* Go ahead and find the base term for both operands. If either base
1955 term is from a pointer or is a named object or a special address
1956 (like an argument or stack reference), then use it for the
1958 rtx base
= find_base_term (tmp1
);
1959 if (base
!= NULL_RTX
1960 && ((REG_P (tmp1
) && REG_POINTER (tmp1
))
1961 || known_base_value_p (base
)))
1963 base
= find_base_term (tmp2
);
1964 if (base
!= NULL_RTX
1965 && ((REG_P (tmp2
) && REG_POINTER (tmp2
))
1966 || known_base_value_p (base
)))
1969 /* We could not determine which of the two operands was the
1970 base register and which was the index. So we can determine
1971 nothing from the base alias check. */
1976 if (CONST_INT_P (XEXP (x
, 1)) && INTVAL (XEXP (x
, 1)) != 0)
1977 return find_base_term (XEXP (x
, 0));
1989 /* Return true if accesses to address X may alias accesses based
1990 on the stack pointer. */
1993 may_be_sp_based_p (rtx x
)
1995 rtx base
= find_base_term (x
);
1996 return !base
|| base
== static_reg_base_value
[STACK_POINTER_REGNUM
];
1999 /* Return 0 if the addresses X and Y are known to point to different
2000 objects, 1 if they might be pointers to the same object. */
2003 base_alias_check (rtx x
, rtx x_base
, rtx y
, rtx y_base
,
2004 machine_mode x_mode
, machine_mode y_mode
)
2006 /* If the address itself has no known base see if a known equivalent
2007 value has one. If either address still has no known base, nothing
2008 is known about aliasing. */
2013 if (! flag_expensive_optimizations
|| (x_c
= canon_rtx (x
)) == x
)
2016 x_base
= find_base_term (x_c
);
2024 if (! flag_expensive_optimizations
|| (y_c
= canon_rtx (y
)) == y
)
2027 y_base
= find_base_term (y_c
);
2032 /* If the base addresses are equal nothing is known about aliasing. */
2033 if (rtx_equal_p (x_base
, y_base
))
2036 /* The base addresses are different expressions. If they are not accessed
2037 via AND, there is no conflict. We can bring knowledge of object
2038 alignment into play here. For example, on alpha, "char a, b;" can
2039 alias one another, though "char a; long b;" cannot. AND addesses may
2040 implicitly alias surrounding objects; i.e. unaligned access in DImode
2041 via AND address can alias all surrounding object types except those
2042 with aligment 8 or higher. */
2043 if (GET_CODE (x
) == AND
&& GET_CODE (y
) == AND
)
2045 if (GET_CODE (x
) == AND
2046 && (!CONST_INT_P (XEXP (x
, 1))
2047 || (int) GET_MODE_UNIT_SIZE (y_mode
) < -INTVAL (XEXP (x
, 1))))
2049 if (GET_CODE (y
) == AND
2050 && (!CONST_INT_P (XEXP (y
, 1))
2051 || (int) GET_MODE_UNIT_SIZE (x_mode
) < -INTVAL (XEXP (y
, 1))))
2054 /* Differing symbols not accessed via AND never alias. */
2055 if (GET_CODE (x_base
) != ADDRESS
&& GET_CODE (y_base
) != ADDRESS
)
2058 if (unique_base_value_p (x_base
) || unique_base_value_p (y_base
))
2064 /* Return TRUE if EXPR refers to a VALUE whose uid is greater than
2068 refs_newer_value_p (const_rtx expr
, rtx v
)
2070 int minuid
= CSELIB_VAL_PTR (v
)->uid
;
2071 subrtx_iterator::array_type array
;
2072 FOR_EACH_SUBRTX (iter
, array
, expr
, NONCONST
)
2073 if (GET_CODE (*iter
) == VALUE
&& CSELIB_VAL_PTR (*iter
)->uid
> minuid
)
2078 /* Convert the address X into something we can use. This is done by returning
2079 it unchanged unless it is a value; in the latter case we call cselib to get
2080 a more useful rtx. */
2086 struct elt_loc_list
*l
;
2088 if (GET_CODE (x
) != VALUE
)
2090 v
= CSELIB_VAL_PTR (x
);
2093 bool have_equivs
= cselib_have_permanent_equivalences ();
2095 v
= canonical_cselib_val (v
);
2096 for (l
= v
->locs
; l
; l
= l
->next
)
2097 if (CONSTANT_P (l
->loc
))
2099 for (l
= v
->locs
; l
; l
= l
->next
)
2100 if (!REG_P (l
->loc
) && !MEM_P (l
->loc
)
2101 /* Avoid infinite recursion when potentially dealing with
2102 var-tracking artificial equivalences, by skipping the
2103 equivalences themselves, and not choosing expressions
2104 that refer to newer VALUEs. */
2106 || (GET_CODE (l
->loc
) != VALUE
2107 && !refs_newer_value_p (l
->loc
, x
))))
2111 for (l
= v
->locs
; l
; l
= l
->next
)
2113 || (GET_CODE (l
->loc
) != VALUE
2114 && !refs_newer_value_p (l
->loc
, x
)))
2116 /* Return the canonical value. */
2120 return v
->locs
->loc
;
2125 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
2126 where SIZE is the size in bytes of the memory reference. If ADDR
2127 is not modified by the memory reference then ADDR is returned. */
2130 addr_side_effect_eval (rtx addr
, int size
, int n_refs
)
2134 switch (GET_CODE (addr
))
2137 offset
= (n_refs
+ 1) * size
;
2140 offset
= -(n_refs
+ 1) * size
;
2143 offset
= n_refs
* size
;
2146 offset
= -n_refs
* size
;
2154 addr
= gen_rtx_PLUS (GET_MODE (addr
), XEXP (addr
, 0),
2155 gen_int_mode (offset
, GET_MODE (addr
)));
2157 addr
= XEXP (addr
, 0);
2158 addr
= canon_rtx (addr
);
2163 /* Return TRUE if an object X sized at XSIZE bytes and another object
2164 Y sized at YSIZE bytes, starting C bytes after X, may overlap. If
2165 any of the sizes is zero, assume an overlap, otherwise use the
2166 absolute value of the sizes as the actual sizes. */
2169 offset_overlap_p (HOST_WIDE_INT c
, int xsize
, int ysize
)
2171 return (xsize
== 0 || ysize
== 0
2174 : (abs (ysize
) > -c
)));
2177 /* Return one if X and Y (memory addresses) reference the
2178 same location in memory or if the references overlap.
2179 Return zero if they do not overlap, else return
2180 minus one in which case they still might reference the same location.
2182 C is an offset accumulator. When
2183 C is nonzero, we are testing aliases between X and Y + C.
2184 XSIZE is the size in bytes of the X reference,
2185 similarly YSIZE is the size in bytes for Y.
2186 Expect that canon_rtx has been already called for X and Y.
2188 If XSIZE or YSIZE is zero, we do not know the amount of memory being
2189 referenced (the reference was BLKmode), so make the most pessimistic
2192 If XSIZE or YSIZE is negative, we may access memory outside the object
2193 being referenced as a side effect. This can happen when using AND to
2194 align memory references, as is done on the Alpha.
2196 Nice to notice that varying addresses cannot conflict with fp if no
2197 local variables had their addresses taken, but that's too hard now.
2199 ??? Contrary to the tree alias oracle this does not return
2200 one for X + non-constant and Y + non-constant when X and Y are equal.
2201 If that is fixed the TBAA hack for union type-punning can be removed. */
2204 memrefs_conflict_p (int xsize
, rtx x
, int ysize
, rtx y
, HOST_WIDE_INT c
)
2206 if (GET_CODE (x
) == VALUE
)
2210 struct elt_loc_list
*l
= NULL
;
2211 if (CSELIB_VAL_PTR (x
))
2212 for (l
= canonical_cselib_val (CSELIB_VAL_PTR (x
))->locs
;
2214 if (REG_P (l
->loc
) && rtx_equal_for_memref_p (l
->loc
, y
))
2221 /* Don't call get_addr if y is the same VALUE. */
2225 if (GET_CODE (y
) == VALUE
)
2229 struct elt_loc_list
*l
= NULL
;
2230 if (CSELIB_VAL_PTR (y
))
2231 for (l
= canonical_cselib_val (CSELIB_VAL_PTR (y
))->locs
;
2233 if (REG_P (l
->loc
) && rtx_equal_for_memref_p (l
->loc
, x
))
2240 /* Don't call get_addr if x is the same VALUE. */
2244 if (GET_CODE (x
) == HIGH
)
2246 else if (GET_CODE (x
) == LO_SUM
)
2249 x
= addr_side_effect_eval (x
, abs (xsize
), 0);
2250 if (GET_CODE (y
) == HIGH
)
2252 else if (GET_CODE (y
) == LO_SUM
)
2255 y
= addr_side_effect_eval (y
, abs (ysize
), 0);
2257 if (rtx_equal_for_memref_p (x
, y
))
2259 return offset_overlap_p (c
, xsize
, ysize
);
2262 /* This code used to check for conflicts involving stack references and
2263 globals but the base address alias code now handles these cases. */
2265 if (GET_CODE (x
) == PLUS
)
2267 /* The fact that X is canonicalized means that this
2268 PLUS rtx is canonicalized. */
2269 rtx x0
= XEXP (x
, 0);
2270 rtx x1
= XEXP (x
, 1);
2272 /* However, VALUEs might end up in different positions even in
2273 canonical PLUSes. Comparing their addresses is enough. */
2275 return memrefs_conflict_p (xsize
, x1
, ysize
, const0_rtx
, c
);
2277 return memrefs_conflict_p (xsize
, x0
, ysize
, const0_rtx
, c
);
2279 if (GET_CODE (y
) == PLUS
)
2281 /* The fact that Y is canonicalized means that this
2282 PLUS rtx is canonicalized. */
2283 rtx y0
= XEXP (y
, 0);
2284 rtx y1
= XEXP (y
, 1);
2287 return memrefs_conflict_p (xsize
, x1
, ysize
, y0
, c
);
2289 return memrefs_conflict_p (xsize
, x0
, ysize
, y1
, c
);
2291 if (rtx_equal_for_memref_p (x1
, y1
))
2292 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
2293 if (rtx_equal_for_memref_p (x0
, y0
))
2294 return memrefs_conflict_p (xsize
, x1
, ysize
, y1
, c
);
2295 if (CONST_INT_P (x1
))
2297 if (CONST_INT_P (y1
))
2298 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
,
2299 c
- INTVAL (x1
) + INTVAL (y1
));
2301 return memrefs_conflict_p (xsize
, x0
, ysize
, y
,
2304 else if (CONST_INT_P (y1
))
2305 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
2309 else if (CONST_INT_P (x1
))
2310 return memrefs_conflict_p (xsize
, x0
, ysize
, y
, c
- INTVAL (x1
));
2312 else if (GET_CODE (y
) == PLUS
)
2314 /* The fact that Y is canonicalized means that this
2315 PLUS rtx is canonicalized. */
2316 rtx y0
= XEXP (y
, 0);
2317 rtx y1
= XEXP (y
, 1);
2320 return memrefs_conflict_p (xsize
, const0_rtx
, ysize
, y1
, c
);
2322 return memrefs_conflict_p (xsize
, const0_rtx
, ysize
, y0
, c
);
2324 if (CONST_INT_P (y1
))
2325 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
2330 if (GET_CODE (x
) == GET_CODE (y
))
2331 switch (GET_CODE (x
))
2335 /* Handle cases where we expect the second operands to be the
2336 same, and check only whether the first operand would conflict
2339 rtx x1
= canon_rtx (XEXP (x
, 1));
2340 rtx y1
= canon_rtx (XEXP (y
, 1));
2341 if (! rtx_equal_for_memref_p (x1
, y1
))
2343 x0
= canon_rtx (XEXP (x
, 0));
2344 y0
= canon_rtx (XEXP (y
, 0));
2345 if (rtx_equal_for_memref_p (x0
, y0
))
2346 return offset_overlap_p (c
, xsize
, ysize
);
2348 /* Can't properly adjust our sizes. */
2349 if (!CONST_INT_P (x1
))
2351 xsize
/= INTVAL (x1
);
2352 ysize
/= INTVAL (x1
);
2354 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
2361 /* Deal with alignment ANDs by adjusting offset and size so as to
2362 cover the maximum range, without taking any previously known
2363 alignment into account. Make a size negative after such an
2364 adjustments, so that, if we end up with e.g. two SYMBOL_REFs, we
2365 assume a potential overlap, because they may end up in contiguous
2366 memory locations and the stricter-alignment access may span over
2368 if (GET_CODE (x
) == AND
&& CONST_INT_P (XEXP (x
, 1)))
2370 HOST_WIDE_INT sc
= INTVAL (XEXP (x
, 1));
2371 unsigned HOST_WIDE_INT uc
= sc
;
2372 if (sc
< 0 && -uc
== (uc
& -uc
))
2379 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2383 if (GET_CODE (y
) == AND
&& CONST_INT_P (XEXP (y
, 1)))
2385 HOST_WIDE_INT sc
= INTVAL (XEXP (y
, 1));
2386 unsigned HOST_WIDE_INT uc
= sc
;
2387 if (sc
< 0 && -uc
== (uc
& -uc
))
2394 return memrefs_conflict_p (xsize
, x
,
2395 ysize
, canon_rtx (XEXP (y
, 0)), c
);
2401 if (CONST_INT_P (x
) && CONST_INT_P (y
))
2403 c
+= (INTVAL (y
) - INTVAL (x
));
2404 return offset_overlap_p (c
, xsize
, ysize
);
2407 if (GET_CODE (x
) == CONST
)
2409 if (GET_CODE (y
) == CONST
)
2410 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2411 ysize
, canon_rtx (XEXP (y
, 0)), c
);
2413 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2416 if (GET_CODE (y
) == CONST
)
2417 return memrefs_conflict_p (xsize
, x
, ysize
,
2418 canon_rtx (XEXP (y
, 0)), c
);
2420 /* Assume a potential overlap for symbolic addresses that went
2421 through alignment adjustments (i.e., that have negative
2422 sizes), because we can't know how far they are from each
2425 return (xsize
< 0 || ysize
< 0 || offset_overlap_p (c
, xsize
, ysize
));
2433 /* Functions to compute memory dependencies.
2435 Since we process the insns in execution order, we can build tables
2436 to keep track of what registers are fixed (and not aliased), what registers
2437 are varying in known ways, and what registers are varying in unknown
2440 If both memory references are volatile, then there must always be a
2441 dependence between the two references, since their order can not be
2442 changed. A volatile and non-volatile reference can be interchanged
2445 We also must allow AND addresses, because they may generate accesses
2446 outside the object being referenced. This is used to generate aligned
2447 addresses from unaligned addresses, for instance, the alpha
2448 storeqi_unaligned pattern. */
2450 /* Read dependence: X is read after read in MEM takes place. There can
2451 only be a dependence here if both reads are volatile, or if either is
2452 an explicit barrier. */
2455 read_dependence (const_rtx mem
, const_rtx x
)
2457 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2459 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2460 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2465 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
2468 decl_for_component_ref (tree x
)
2472 x
= TREE_OPERAND (x
, 0);
2474 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
2476 return x
&& DECL_P (x
) ? x
: NULL_TREE
;
2479 /* Walk up the COMPONENT_REF list in X and adjust *OFFSET to compensate
2480 for the offset of the field reference. *KNOWN_P says whether the
2484 adjust_offset_for_component_ref (tree x
, bool *known_p
,
2485 HOST_WIDE_INT
*offset
)
2491 tree xoffset
= component_ref_field_offset (x
);
2492 tree field
= TREE_OPERAND (x
, 1);
2493 if (TREE_CODE (xoffset
) != INTEGER_CST
)
2500 = (wi::to_offset (xoffset
)
2501 + wi::lrshift (wi::to_offset (DECL_FIELD_BIT_OFFSET (field
)),
2502 LOG2_BITS_PER_UNIT
));
2503 if (!wi::fits_uhwi_p (woffset
))
2508 *offset
+= woffset
.to_uhwi ();
2510 x
= TREE_OPERAND (x
, 0);
2512 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
2515 /* Return nonzero if we can determine the exprs corresponding to memrefs
2516 X and Y and they do not overlap.
2517 If LOOP_VARIANT is set, skip offset-based disambiguation */
2520 nonoverlapping_memrefs_p (const_rtx x
, const_rtx y
, bool loop_invariant
)
2522 tree exprx
= MEM_EXPR (x
), expry
= MEM_EXPR (y
);
2525 bool moffsetx_known_p
, moffsety_known_p
;
2526 HOST_WIDE_INT moffsetx
= 0, moffsety
= 0;
2527 HOST_WIDE_INT offsetx
= 0, offsety
= 0, sizex
, sizey
;
2529 /* Unless both have exprs, we can't tell anything. */
2530 if (exprx
== 0 || expry
== 0)
2533 /* For spill-slot accesses make sure we have valid offsets. */
2534 if ((exprx
== get_spill_slot_decl (false)
2535 && ! MEM_OFFSET_KNOWN_P (x
))
2536 || (expry
== get_spill_slot_decl (false)
2537 && ! MEM_OFFSET_KNOWN_P (y
)))
2540 /* If the field reference test failed, look at the DECLs involved. */
2541 moffsetx_known_p
= MEM_OFFSET_KNOWN_P (x
);
2542 if (moffsetx_known_p
)
2543 moffsetx
= MEM_OFFSET (x
);
2544 if (TREE_CODE (exprx
) == COMPONENT_REF
)
2546 tree t
= decl_for_component_ref (exprx
);
2549 adjust_offset_for_component_ref (exprx
, &moffsetx_known_p
, &moffsetx
);
2553 moffsety_known_p
= MEM_OFFSET_KNOWN_P (y
);
2554 if (moffsety_known_p
)
2555 moffsety
= MEM_OFFSET (y
);
2556 if (TREE_CODE (expry
) == COMPONENT_REF
)
2558 tree t
= decl_for_component_ref (expry
);
2561 adjust_offset_for_component_ref (expry
, &moffsety_known_p
, &moffsety
);
2565 if (! DECL_P (exprx
) || ! DECL_P (expry
))
2568 /* If we refer to different gimple registers, or one gimple register
2569 and one non-gimple-register, we know they can't overlap. First,
2570 gimple registers don't have their addresses taken. Now, there
2571 could be more than one stack slot for (different versions of) the
2572 same gimple register, but we can presumably tell they don't
2573 overlap based on offsets from stack base addresses elsewhere.
2574 It's important that we don't proceed to DECL_RTL, because gimple
2575 registers may not pass DECL_RTL_SET_P, and make_decl_rtl won't be
2576 able to do anything about them since no SSA information will have
2577 remained to guide it. */
2578 if (is_gimple_reg (exprx
) || is_gimple_reg (expry
))
2579 return exprx
!= expry
2580 || (moffsetx_known_p
&& moffsety_known_p
2581 && MEM_SIZE_KNOWN_P (x
) && MEM_SIZE_KNOWN_P (y
)
2582 && !offset_overlap_p (moffsety
- moffsetx
,
2583 MEM_SIZE (x
), MEM_SIZE (y
)));
2585 /* With invalid code we can end up storing into the constant pool.
2586 Bail out to avoid ICEing when creating RTL for this.
2587 See gfortran.dg/lto/20091028-2_0.f90. */
2588 if (TREE_CODE (exprx
) == CONST_DECL
2589 || TREE_CODE (expry
) == CONST_DECL
)
2592 rtlx
= DECL_RTL (exprx
);
2593 rtly
= DECL_RTL (expry
);
2595 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
2596 can't overlap unless they are the same because we never reuse that part
2597 of the stack frame used for locals for spilled pseudos. */
2598 if ((!MEM_P (rtlx
) || !MEM_P (rtly
))
2599 && ! rtx_equal_p (rtlx
, rtly
))
2602 /* If we have MEMs referring to different address spaces (which can
2603 potentially overlap), we cannot easily tell from the addresses
2604 whether the references overlap. */
2605 if (MEM_P (rtlx
) && MEM_P (rtly
)
2606 && MEM_ADDR_SPACE (rtlx
) != MEM_ADDR_SPACE (rtly
))
2609 /* Get the base and offsets of both decls. If either is a register, we
2610 know both are and are the same, so use that as the base. The only
2611 we can avoid overlap is if we can deduce that they are nonoverlapping
2612 pieces of that decl, which is very rare. */
2613 basex
= MEM_P (rtlx
) ? XEXP (rtlx
, 0) : rtlx
;
2614 if (GET_CODE (basex
) == PLUS
&& CONST_INT_P (XEXP (basex
, 1)))
2615 offsetx
= INTVAL (XEXP (basex
, 1)), basex
= XEXP (basex
, 0);
2617 basey
= MEM_P (rtly
) ? XEXP (rtly
, 0) : rtly
;
2618 if (GET_CODE (basey
) == PLUS
&& CONST_INT_P (XEXP (basey
, 1)))
2619 offsety
= INTVAL (XEXP (basey
, 1)), basey
= XEXP (basey
, 0);
2621 /* If the bases are different, we know they do not overlap if both
2622 are constants or if one is a constant and the other a pointer into the
2623 stack frame. Otherwise a different base means we can't tell if they
2625 if (! rtx_equal_p (basex
, basey
))
2626 return ((CONSTANT_P (basex
) && CONSTANT_P (basey
))
2627 || (CONSTANT_P (basex
) && REG_P (basey
)
2628 && REGNO_PTR_FRAME_P (REGNO (basey
)))
2629 || (CONSTANT_P (basey
) && REG_P (basex
)
2630 && REGNO_PTR_FRAME_P (REGNO (basex
))));
2632 /* Offset based disambiguation not appropriate for loop invariant */
2636 sizex
= (!MEM_P (rtlx
) ? (int) GET_MODE_SIZE (GET_MODE (rtlx
))
2637 : MEM_SIZE_KNOWN_P (rtlx
) ? MEM_SIZE (rtlx
)
2639 sizey
= (!MEM_P (rtly
) ? (int) GET_MODE_SIZE (GET_MODE (rtly
))
2640 : MEM_SIZE_KNOWN_P (rtly
) ? MEM_SIZE (rtly
)
2643 /* If we have an offset for either memref, it can update the values computed
2645 if (moffsetx_known_p
)
2646 offsetx
+= moffsetx
, sizex
-= moffsetx
;
2647 if (moffsety_known_p
)
2648 offsety
+= moffsety
, sizey
-= moffsety
;
2650 /* If a memref has both a size and an offset, we can use the smaller size.
2651 We can't do this if the offset isn't known because we must view this
2652 memref as being anywhere inside the DECL's MEM. */
2653 if (MEM_SIZE_KNOWN_P (x
) && moffsetx_known_p
)
2654 sizex
= MEM_SIZE (x
);
2655 if (MEM_SIZE_KNOWN_P (y
) && moffsety_known_p
)
2656 sizey
= MEM_SIZE (y
);
2658 /* Put the values of the memref with the lower offset in X's values. */
2659 if (offsetx
> offsety
)
2661 std::swap (offsetx
, offsety
);
2662 std::swap (sizex
, sizey
);
2665 /* If we don't know the size of the lower-offset value, we can't tell
2666 if they conflict. Otherwise, we do the test. */
2667 return sizex
>= 0 && offsety
>= offsetx
+ sizex
;
2670 /* Helper for true_dependence and canon_true_dependence.
2671 Checks for true dependence: X is read after store in MEM takes place.
2673 If MEM_CANONICALIZED is FALSE, then X_ADDR and MEM_ADDR should be
2674 NULL_RTX, and the canonical addresses of MEM and X are both computed
2675 here. If MEM_CANONICALIZED, then MEM must be already canonicalized.
2677 If X_ADDR is non-NULL, it is used in preference of XEXP (x, 0).
2679 Returns 1 if there is a true dependence, 0 otherwise. */
2682 true_dependence_1 (const_rtx mem
, machine_mode mem_mode
, rtx mem_addr
,
2683 const_rtx x
, rtx x_addr
, bool mem_canonicalized
)
2689 gcc_checking_assert (mem_canonicalized
? (mem_addr
!= NULL_RTX
)
2690 : (mem_addr
== NULL_RTX
&& x_addr
== NULL_RTX
));
2692 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2695 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2696 This is used in epilogue deallocation functions, and in cselib. */
2697 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2699 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2701 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2702 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2706 x_addr
= XEXP (x
, 0);
2707 x_addr
= get_addr (x_addr
);
2711 mem_addr
= XEXP (mem
, 0);
2712 if (mem_mode
== VOIDmode
)
2713 mem_mode
= GET_MODE (mem
);
2715 true_mem_addr
= get_addr (mem_addr
);
2717 /* Read-only memory is by definition never modified, and therefore can't
2718 conflict with anything. However, don't assume anything when AND
2719 addresses are involved and leave to the code below to determine
2720 dependence. We don't expect to find read-only set on MEM, but
2721 stupid user tricks can produce them, so don't die. */
2722 if (MEM_READONLY_P (x
)
2723 && GET_CODE (x_addr
) != AND
2724 && GET_CODE (true_mem_addr
) != AND
)
2727 /* If we have MEMs referring to different address spaces (which can
2728 potentially overlap), we cannot easily tell from the addresses
2729 whether the references overlap. */
2730 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
2733 base
= find_base_term (x_addr
);
2734 if (base
&& (GET_CODE (base
) == LABEL_REF
2735 || (GET_CODE (base
) == SYMBOL_REF
2736 && CONSTANT_POOL_ADDRESS_P (base
))))
2739 rtx mem_base
= find_base_term (true_mem_addr
);
2740 if (! base_alias_check (x_addr
, base
, true_mem_addr
, mem_base
,
2741 GET_MODE (x
), mem_mode
))
2744 x_addr
= canon_rtx (x_addr
);
2745 if (!mem_canonicalized
)
2746 mem_addr
= canon_rtx (true_mem_addr
);
2748 if ((ret
= memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
2749 SIZE_FOR_MODE (x
), x_addr
, 0)) != -1)
2752 if (mems_in_disjoint_alias_sets_p (x
, mem
))
2755 if (nonoverlapping_memrefs_p (mem
, x
, false))
2758 return rtx_refs_may_alias_p (x
, mem
, true);
2761 /* True dependence: X is read after store in MEM takes place. */
2764 true_dependence (const_rtx mem
, machine_mode mem_mode
, const_rtx x
)
2766 return true_dependence_1 (mem
, mem_mode
, NULL_RTX
,
2767 x
, NULL_RTX
, /*mem_canonicalized=*/false);
2770 /* Canonical true dependence: X is read after store in MEM takes place.
2771 Variant of true_dependence which assumes MEM has already been
2772 canonicalized (hence we no longer do that here).
2773 The mem_addr argument has been added, since true_dependence_1 computed
2774 this value prior to canonicalizing. */
2777 canon_true_dependence (const_rtx mem
, machine_mode mem_mode
, rtx mem_addr
,
2778 const_rtx x
, rtx x_addr
)
2780 return true_dependence_1 (mem
, mem_mode
, mem_addr
,
2781 x
, x_addr
, /*mem_canonicalized=*/true);
2784 /* Returns nonzero if a write to X might alias a previous read from
2785 (or, if WRITEP is true, a write to) MEM.
2786 If X_CANONCALIZED is true, then X_ADDR is the canonicalized address of X,
2787 and X_MODE the mode for that access.
2788 If MEM_CANONICALIZED is true, MEM is canonicalized. */
2791 write_dependence_p (const_rtx mem
,
2792 const_rtx x
, machine_mode x_mode
, rtx x_addr
,
2793 bool mem_canonicalized
, bool x_canonicalized
, bool writep
)
2796 rtx true_mem_addr
, true_x_addr
;
2800 gcc_checking_assert (x_canonicalized
2801 ? (x_addr
!= NULL_RTX
&& x_mode
!= VOIDmode
)
2802 : (x_addr
== NULL_RTX
&& x_mode
== VOIDmode
));
2804 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2807 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2808 This is used in epilogue deallocation functions. */
2809 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2811 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2813 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2814 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2818 x_addr
= XEXP (x
, 0);
2819 true_x_addr
= get_addr (x_addr
);
2821 mem_addr
= XEXP (mem
, 0);
2822 true_mem_addr
= get_addr (mem_addr
);
2824 /* A read from read-only memory can't conflict with read-write memory.
2825 Don't assume anything when AND addresses are involved and leave to
2826 the code below to determine dependence. */
2828 && MEM_READONLY_P (mem
)
2829 && GET_CODE (true_x_addr
) != AND
2830 && GET_CODE (true_mem_addr
) != AND
)
2833 /* If we have MEMs referring to different address spaces (which can
2834 potentially overlap), we cannot easily tell from the addresses
2835 whether the references overlap. */
2836 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
2839 base
= find_base_term (true_mem_addr
);
2842 && (GET_CODE (base
) == LABEL_REF
2843 || (GET_CODE (base
) == SYMBOL_REF
2844 && CONSTANT_POOL_ADDRESS_P (base
))))
2847 rtx x_base
= find_base_term (true_x_addr
);
2848 if (! base_alias_check (true_x_addr
, x_base
, true_mem_addr
, base
,
2849 GET_MODE (x
), GET_MODE (mem
)))
2852 if (!x_canonicalized
)
2854 x_addr
= canon_rtx (true_x_addr
);
2855 x_mode
= GET_MODE (x
);
2857 if (!mem_canonicalized
)
2858 mem_addr
= canon_rtx (true_mem_addr
);
2860 if ((ret
= memrefs_conflict_p (SIZE_FOR_MODE (mem
), mem_addr
,
2861 GET_MODE_SIZE (x_mode
), x_addr
, 0)) != -1)
2864 if (nonoverlapping_memrefs_p (x
, mem
, false))
2867 return rtx_refs_may_alias_p (x
, mem
, false);
2870 /* Anti dependence: X is written after read in MEM takes place. */
2873 anti_dependence (const_rtx mem
, const_rtx x
)
2875 return write_dependence_p (mem
, x
, VOIDmode
, NULL_RTX
,
2876 /*mem_canonicalized=*/false,
2877 /*x_canonicalized*/false, /*writep=*/false);
2880 /* Likewise, but we already have a canonicalized MEM, and X_ADDR for X.
2881 Also, consider X in X_MODE (which might be from an enclosing
2882 STRICT_LOW_PART / ZERO_EXTRACT).
2883 If MEM_CANONICALIZED is true, MEM is canonicalized. */
2886 canon_anti_dependence (const_rtx mem
, bool mem_canonicalized
,
2887 const_rtx x
, machine_mode x_mode
, rtx x_addr
)
2889 return write_dependence_p (mem
, x
, x_mode
, x_addr
,
2890 mem_canonicalized
, /*x_canonicalized=*/true,
2894 /* Output dependence: X is written after store in MEM takes place. */
2897 output_dependence (const_rtx mem
, const_rtx x
)
2899 return write_dependence_p (mem
, x
, VOIDmode
, NULL_RTX
,
2900 /*mem_canonicalized=*/false,
2901 /*x_canonicalized*/false, /*writep=*/true);
2906 /* Check whether X may be aliased with MEM. Don't do offset-based
2907 memory disambiguation & TBAA. */
2909 may_alias_p (const_rtx mem
, const_rtx x
)
2911 rtx x_addr
, mem_addr
;
2913 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2916 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2917 This is used in epilogue deallocation functions. */
2918 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2920 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2922 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2923 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2926 x_addr
= XEXP (x
, 0);
2927 x_addr
= get_addr (x_addr
);
2929 mem_addr
= XEXP (mem
, 0);
2930 mem_addr
= get_addr (mem_addr
);
2932 /* Read-only memory is by definition never modified, and therefore can't
2933 conflict with anything. However, don't assume anything when AND
2934 addresses are involved and leave to the code below to determine
2935 dependence. We don't expect to find read-only set on MEM, but
2936 stupid user tricks can produce them, so don't die. */
2937 if (MEM_READONLY_P (x
)
2938 && GET_CODE (x_addr
) != AND
2939 && GET_CODE (mem_addr
) != AND
)
2942 /* If we have MEMs referring to different address spaces (which can
2943 potentially overlap), we cannot easily tell from the addresses
2944 whether the references overlap. */
2945 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
2948 rtx x_base
= find_base_term (x_addr
);
2949 rtx mem_base
= find_base_term (mem_addr
);
2950 if (! base_alias_check (x_addr
, x_base
, mem_addr
, mem_base
,
2951 GET_MODE (x
), GET_MODE (mem_addr
)))
2954 if (nonoverlapping_memrefs_p (mem
, x
, true))
2957 /* TBAA not valid for loop_invarint */
2958 return rtx_refs_may_alias_p (x
, mem
, false);
2962 init_alias_target (void)
2966 if (!arg_base_value
)
2967 arg_base_value
= gen_rtx_ADDRESS (VOIDmode
, 0);
2969 memset (static_reg_base_value
, 0, sizeof static_reg_base_value
);
2971 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2972 /* Check whether this register can hold an incoming pointer
2973 argument. FUNCTION_ARG_REGNO_P tests outgoing register
2974 numbers, so translate if necessary due to register windows. */
2975 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i
))
2976 && HARD_REGNO_MODE_OK (i
, Pmode
))
2977 static_reg_base_value
[i
] = arg_base_value
;
2979 static_reg_base_value
[STACK_POINTER_REGNUM
]
2980 = unique_base_value (UNIQUE_BASE_VALUE_SP
);
2981 static_reg_base_value
[ARG_POINTER_REGNUM
]
2982 = unique_base_value (UNIQUE_BASE_VALUE_ARGP
);
2983 static_reg_base_value
[FRAME_POINTER_REGNUM
]
2984 = unique_base_value (UNIQUE_BASE_VALUE_FP
);
2985 if (!HARD_FRAME_POINTER_IS_FRAME_POINTER
)
2986 static_reg_base_value
[HARD_FRAME_POINTER_REGNUM
]
2987 = unique_base_value (UNIQUE_BASE_VALUE_HFP
);
2990 /* Set MEMORY_MODIFIED when X modifies DATA (that is assumed
2991 to be memory reference. */
2992 static bool memory_modified
;
2994 memory_modified_1 (rtx x
, const_rtx pat ATTRIBUTE_UNUSED
, void *data
)
2998 if (anti_dependence (x
, (const_rtx
)data
) || output_dependence (x
, (const_rtx
)data
))
2999 memory_modified
= true;
3004 /* Return true when INSN possibly modify memory contents of MEM
3005 (i.e. address can be modified). */
3007 memory_modified_in_insn_p (const_rtx mem
, const_rtx insn
)
3011 memory_modified
= false;
3012 note_stores (PATTERN (insn
), memory_modified_1
, CONST_CAST_RTX(mem
));
3013 return memory_modified
;
3016 /* Return TRUE if the destination of a set is rtx identical to
3019 set_dest_equal_p (const_rtx set
, const_rtx item
)
3021 rtx dest
= SET_DEST (set
);
3022 return rtx_equal_p (dest
, item
);
3025 /* Like memory_modified_in_insn_p, but return TRUE if INSN will
3026 *DEFINITELY* modify the memory contents of MEM. */
3028 memory_must_be_modified_in_insn_p (const_rtx mem
, const_rtx insn
)
3032 insn
= PATTERN (insn
);
3033 if (GET_CODE (insn
) == SET
)
3034 return set_dest_equal_p (insn
, mem
);
3035 else if (GET_CODE (insn
) == PARALLEL
)
3038 for (i
= 0; i
< XVECLEN (insn
, 0); i
++)
3040 rtx sub
= XVECEXP (insn
, 0, i
);
3041 if (GET_CODE (sub
) == SET
3042 && set_dest_equal_p (sub
, mem
))
3049 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
3053 init_alias_analysis (void)
3055 unsigned int maxreg
= max_reg_num ();
3064 timevar_push (TV_ALIAS_ANALYSIS
);
3066 vec_safe_grow_cleared (reg_known_value
, maxreg
- FIRST_PSEUDO_REGISTER
);
3067 reg_known_equiv_p
= sbitmap_alloc (maxreg
- FIRST_PSEUDO_REGISTER
);
3068 bitmap_clear (reg_known_equiv_p
);
3070 /* If we have memory allocated from the previous run, use it. */
3071 if (old_reg_base_value
)
3072 reg_base_value
= old_reg_base_value
;
3075 reg_base_value
->truncate (0);
3077 vec_safe_grow_cleared (reg_base_value
, maxreg
);
3079 new_reg_base_value
= XNEWVEC (rtx
, maxreg
);
3080 reg_seen
= sbitmap_alloc (maxreg
);
3082 /* The basic idea is that each pass through this loop will use the
3083 "constant" information from the previous pass to propagate alias
3084 information through another level of assignments.
3086 The propagation is done on the CFG in reverse post-order, to propagate
3087 things forward as far as possible in each iteration.
3089 This could get expensive if the assignment chains are long. Maybe
3090 we should throttle the number of iterations, possibly based on
3091 the optimization level or flag_expensive_optimizations.
3093 We could propagate more information in the first pass by making use
3094 of DF_REG_DEF_COUNT to determine immediately that the alias information
3095 for a pseudo is "constant".
3097 A program with an uninitialized variable can cause an infinite loop
3098 here. Instead of doing a full dataflow analysis to detect such problems
3099 we just cap the number of iterations for the loop.
3101 The state of the arrays for the set chain in question does not matter
3102 since the program has undefined behavior. */
3104 rpo
= XNEWVEC (int, n_basic_blocks_for_fn (cfun
));
3105 rpo_cnt
= pre_and_rev_post_order_compute (NULL
, rpo
, false);
3107 /* The prologue/epilogue insns are not threaded onto the
3108 insn chain until after reload has completed. Thus,
3109 there is no sense wasting time checking if INSN is in
3110 the prologue/epilogue until after reload has completed. */
3111 bool could_be_prologue_epilogue
= ((targetm
.have_prologue ()
3112 || targetm
.have_epilogue ())
3113 && reload_completed
);
3118 /* Assume nothing will change this iteration of the loop. */
3121 /* We want to assign the same IDs each iteration of this loop, so
3122 start counting from one each iteration of the loop. */
3125 /* We're at the start of the function each iteration through the
3126 loop, so we're copying arguments. */
3127 copying_arguments
= true;
3129 /* Wipe the potential alias information clean for this pass. */
3130 memset (new_reg_base_value
, 0, maxreg
* sizeof (rtx
));
3132 /* Wipe the reg_seen array clean. */
3133 bitmap_clear (reg_seen
);
3135 /* Initialize the alias information for this pass. */
3136 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3137 if (static_reg_base_value
[i
])
3139 new_reg_base_value
[i
] = static_reg_base_value
[i
];
3140 bitmap_set_bit (reg_seen
, i
);
3143 /* Walk the insns adding values to the new_reg_base_value array. */
3144 for (i
= 0; i
< rpo_cnt
; i
++)
3146 basic_block bb
= BASIC_BLOCK_FOR_FN (cfun
, rpo
[i
]);
3147 FOR_BB_INSNS (bb
, insn
)
3149 if (NONDEBUG_INSN_P (insn
))
3153 if (could_be_prologue_epilogue
3154 && prologue_epilogue_contains (insn
))
3157 /* If this insn has a noalias note, process it, Otherwise,
3158 scan for sets. A simple set will have no side effects
3159 which could change the base value of any other register. */
3161 if (GET_CODE (PATTERN (insn
)) == SET
3162 && REG_NOTES (insn
) != 0
3163 && find_reg_note (insn
, REG_NOALIAS
, NULL_RTX
))
3164 record_set (SET_DEST (PATTERN (insn
)), NULL_RTX
, NULL
);
3166 note_stores (PATTERN (insn
), record_set
, NULL
);
3168 set
= single_set (insn
);
3171 && REG_P (SET_DEST (set
))
3172 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
)
3174 unsigned int regno
= REGNO (SET_DEST (set
));
3175 rtx src
= SET_SRC (set
);
3178 note
= find_reg_equal_equiv_note (insn
);
3179 if (note
&& REG_NOTE_KIND (note
) == REG_EQUAL
3180 && DF_REG_DEF_COUNT (regno
) != 1)
3183 if (note
!= NULL_RTX
3184 && GET_CODE (XEXP (note
, 0)) != EXPR_LIST
3185 && ! rtx_varies_p (XEXP (note
, 0), 1)
3186 && ! reg_overlap_mentioned_p (SET_DEST (set
),
3189 set_reg_known_value (regno
, XEXP (note
, 0));
3190 set_reg_known_equiv_p (regno
,
3191 REG_NOTE_KIND (note
) == REG_EQUIV
);
3193 else if (DF_REG_DEF_COUNT (regno
) == 1
3194 && GET_CODE (src
) == PLUS
3195 && REG_P (XEXP (src
, 0))
3196 && (t
= get_reg_known_value (REGNO (XEXP (src
, 0))))
3197 && CONST_INT_P (XEXP (src
, 1)))
3199 t
= plus_constant (GET_MODE (src
), t
,
3200 INTVAL (XEXP (src
, 1)));
3201 set_reg_known_value (regno
, t
);
3202 set_reg_known_equiv_p (regno
, false);
3204 else if (DF_REG_DEF_COUNT (regno
) == 1
3205 && ! rtx_varies_p (src
, 1))
3207 set_reg_known_value (regno
, src
);
3208 set_reg_known_equiv_p (regno
, false);
3212 else if (NOTE_P (insn
)
3213 && NOTE_KIND (insn
) == NOTE_INSN_FUNCTION_BEG
)
3214 copying_arguments
= false;
3218 /* Now propagate values from new_reg_base_value to reg_base_value. */
3219 gcc_assert (maxreg
== (unsigned int) max_reg_num ());
3221 for (ui
= 0; ui
< maxreg
; ui
++)
3223 if (new_reg_base_value
[ui
]
3224 && new_reg_base_value
[ui
] != (*reg_base_value
)[ui
]
3225 && ! rtx_equal_p (new_reg_base_value
[ui
], (*reg_base_value
)[ui
]))
3227 (*reg_base_value
)[ui
] = new_reg_base_value
[ui
];
3232 while (changed
&& ++pass
< MAX_ALIAS_LOOP_PASSES
);
3235 /* Fill in the remaining entries. */
3236 FOR_EACH_VEC_ELT (*reg_known_value
, i
, val
)
3238 int regno
= i
+ FIRST_PSEUDO_REGISTER
;
3240 set_reg_known_value (regno
, regno_reg_rtx
[regno
]);
3244 free (new_reg_base_value
);
3245 new_reg_base_value
= 0;
3246 sbitmap_free (reg_seen
);
3248 timevar_pop (TV_ALIAS_ANALYSIS
);
3251 /* Equate REG_BASE_VALUE (reg1) to REG_BASE_VALUE (reg2).
3252 Special API for var-tracking pass purposes. */
3255 vt_equate_reg_base_value (const_rtx reg1
, const_rtx reg2
)
3257 (*reg_base_value
)[REGNO (reg1
)] = REG_BASE_VALUE (reg2
);
3261 end_alias_analysis (void)
3263 old_reg_base_value
= reg_base_value
;
3264 vec_free (reg_known_value
);
3265 sbitmap_free (reg_known_equiv_p
);
3269 dump_alias_stats_in_alias_c (FILE *s
)
3271 fprintf (s
, " TBAA oracle: %llu disambiguations %llu queries\n"
3272 " %llu are in alias set 0\n"
3273 " %llu queries asked about the same object\n"
3274 " %llu queries asked about the same alias set\n"
3275 " %llu access volatile\n"
3276 " %llu are dependent in the DAG\n"
3277 " %llu are aritificially in conflict with void *\n",
3278 alias_stats
.num_disambiguated
,
3279 alias_stats
.num_alias_zero
+ alias_stats
.num_same_alias_set
3280 + alias_stats
.num_same_objects
+ alias_stats
.num_volatile
3281 + alias_stats
.num_dag
+ alias_stats
.num_disambiguated
3282 + alias_stats
.num_universal
,
3283 alias_stats
.num_alias_zero
, alias_stats
.num_same_alias_set
,
3284 alias_stats
.num_same_objects
, alias_stats
.num_volatile
,
3285 alias_stats
.num_dag
, alias_stats
.num_universal
);
3287 #include "gt-alias.h"