1 /* Alias analysis for GNU C
2 Copyright (C) 1997-2019 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"
32 #include "gimple-ssa.h"
35 #include "fold-const.h"
38 #include "langhooks.h"
43 /* The aliasing API provided here solves related but different problems:
45 Say there exists (in c)
59 Consider the four questions:
61 Can a store to x1 interfere with px2->y1?
62 Can a store to x1 interfere with px2->z2?
63 Can a store to x1 change the value pointed to by with py?
64 Can a store to x1 change the value pointed to by with pz?
66 The answer to these questions can be yes, yes, yes, and maybe.
68 The first two questions can be answered with a simple examination
69 of the type system. If structure X contains a field of type Y then
70 a store through a pointer to an X can overwrite any field that is
71 contained (recursively) in an X (unless we know that px1 != px2).
73 The last two questions can be solved in the same way as the first
74 two questions but this is too conservative. The observation is
75 that in some cases we can know which (if any) fields are addressed
76 and if those addresses are used in bad ways. This analysis may be
77 language specific. In C, arbitrary operations may be applied to
78 pointers. However, there is some indication that this may be too
79 conservative for some C++ types.
81 The pass ipa-type-escape does this analysis for the types whose
82 instances do not escape across the compilation boundary.
84 Historically in GCC, these two problems were combined and a single
85 data structure that was used to represent the solution to these
86 problems. We now have two similar but different data structures,
87 The data structure to solve the last two questions is similar to
88 the first, but does not contain the fields whose address are never
89 taken. For types that do escape the compilation unit, the data
90 structures will have identical information.
93 /* The alias sets assigned to MEMs assist the back-end in determining
94 which MEMs can alias which other MEMs. In general, two MEMs in
95 different alias sets cannot alias each other, with one important
96 exception. Consider something like:
98 struct S { int i; double d; };
100 a store to an `S' can alias something of either type `int' or type
101 `double'. (However, a store to an `int' cannot alias a `double'
102 and vice versa.) We indicate this via a tree structure that looks
110 (The arrows are directed and point downwards.)
111 In this situation we say the alias set for `struct S' is the
112 `superset' and that those for `int' and `double' are `subsets'.
114 To see whether two alias sets can point to the same memory, we must
115 see if either alias set is a subset of the other. We need not trace
116 past immediate descendants, however, since we propagate all
117 grandchildren up one level.
119 Alias set zero is implicitly a superset of all other alias sets.
120 However, this is no actual entry for alias set zero. It is an
121 error to attempt to explicitly construct a subset of zero. */
123 struct alias_set_hash
: int_hash
<int, INT_MIN
, INT_MIN
+ 1> {};
125 struct GTY(()) alias_set_entry
{
126 /* The alias set number, as stored in MEM_ALIAS_SET. */
127 alias_set_type alias_set
;
129 /* Nonzero if would have a child of zero: this effectively makes this
130 alias set the same as alias set zero. */
132 /* Nonzero if alias set corresponds to pointer type itself (i.e. not to
133 aggregate contaiing pointer.
134 This is used for a special case where we need an universal pointer type
135 compatible with all other pointer types. */
137 /* Nonzero if is_pointer or if one of childs have has_pointer set. */
140 /* The children of the alias set. These are not just the immediate
141 children, but, in fact, all descendants. So, if we have:
143 struct T { struct S s; float f; }
145 continuing our example above, the children here will be all of
146 `int', `double', `float', and `struct S'. */
147 hash_map
<alias_set_hash
, int> *children
;
150 static int rtx_equal_for_memref_p (const_rtx
, const_rtx
);
151 static void record_set (rtx
, const_rtx
, void *);
152 static int base_alias_check (rtx
, rtx
, rtx
, rtx
, machine_mode
,
154 static rtx
find_base_value (rtx
);
155 static int mems_in_disjoint_alias_sets_p (const_rtx
, const_rtx
);
156 static alias_set_entry
*get_alias_set_entry (alias_set_type
);
157 static tree
decl_for_component_ref (tree
);
158 static int write_dependence_p (const_rtx
,
159 const_rtx
, machine_mode
, rtx
,
161 static int compare_base_symbol_refs (const_rtx
, const_rtx
);
163 static void memory_modified_1 (rtx
, const_rtx
, void *);
165 /* Query statistics for the different low-level disambiguators.
166 A high-level query may trigger multiple of them. */
169 unsigned long long num_alias_zero
;
170 unsigned long long num_same_alias_set
;
171 unsigned long long num_same_objects
;
172 unsigned long long num_volatile
;
173 unsigned long long num_dag
;
174 unsigned long long num_universal
;
175 unsigned long long num_disambiguated
;
179 /* Set up all info needed to perform alias analysis on memory references. */
181 /* Returns the size in bytes of the mode of X. */
182 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
184 /* Cap the number of passes we make over the insns propagating alias
185 information through set chains.
186 ??? 10 is a completely arbitrary choice. This should be based on the
187 maximum loop depth in the CFG, but we do not have this information
188 available (even if current_loops _is_ available). */
189 #define MAX_ALIAS_LOOP_PASSES 10
191 /* reg_base_value[N] gives an address to which register N is related.
192 If all sets after the first add or subtract to the current value
193 or otherwise modify it so it does not point to a different top level
194 object, reg_base_value[N] is equal to the address part of the source
197 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
198 expressions represent three types of base:
200 1. incoming arguments. There is just one ADDRESS to represent all
201 arguments, since we do not know at this level whether accesses
202 based on different arguments can alias. The ADDRESS has id 0.
204 2. stack_pointer_rtx, frame_pointer_rtx, hard_frame_pointer_rtx
205 (if distinct from frame_pointer_rtx) and arg_pointer_rtx.
206 Each of these rtxes has a separate ADDRESS associated with it,
207 each with a negative id.
209 GCC is (and is required to be) precise in which register it
210 chooses to access a particular region of stack. We can therefore
211 assume that accesses based on one of these rtxes do not alias
212 accesses based on another of these rtxes.
214 3. bases that are derived from malloc()ed memory (REG_NOALIAS).
215 Each such piece of memory has a separate ADDRESS associated
216 with it, each with an id greater than 0.
218 Accesses based on one ADDRESS do not alias accesses based on other
219 ADDRESSes. Accesses based on ADDRESSes in groups (2) and (3) do not
220 alias globals either; the ADDRESSes have Pmode to indicate this.
221 The ADDRESS in group (1) _may_ alias globals; it has VOIDmode to
224 static GTY(()) vec
<rtx
, va_gc
> *reg_base_value
;
225 static rtx
*new_reg_base_value
;
227 /* The single VOIDmode ADDRESS that represents all argument bases.
229 static GTY(()) rtx arg_base_value
;
231 /* Used to allocate unique ids to each REG_NOALIAS ADDRESS. */
232 static int unique_id
;
234 /* We preserve the copy of old array around to avoid amount of garbage
235 produced. About 8% of garbage produced were attributed to this
237 static GTY((deletable
)) vec
<rtx
, va_gc
> *old_reg_base_value
;
239 /* Values of XINT (address, 0) of Pmode ADDRESS rtxes for special
241 #define UNIQUE_BASE_VALUE_SP -1
242 #define UNIQUE_BASE_VALUE_ARGP -2
243 #define UNIQUE_BASE_VALUE_FP -3
244 #define UNIQUE_BASE_VALUE_HFP -4
246 #define static_reg_base_value \
247 (this_target_rtl->x_static_reg_base_value)
249 #define REG_BASE_VALUE(X) \
250 (REGNO (X) < vec_safe_length (reg_base_value) \
251 ? (*reg_base_value)[REGNO (X)] : 0)
253 /* Vector indexed by N giving the initial (unchanging) value known for
254 pseudo-register N. This vector is initialized in init_alias_analysis,
255 and does not change until end_alias_analysis is called. */
256 static GTY(()) vec
<rtx
, va_gc
> *reg_known_value
;
258 /* Vector recording for each reg_known_value whether it is due to a
259 REG_EQUIV note. Future passes (viz., reload) may replace the
260 pseudo with the equivalent expression and so we account for the
261 dependences that would be introduced if that happens.
263 The REG_EQUIV notes created in assign_parms may mention the arg
264 pointer, and there are explicit insns in the RTL that modify the
265 arg pointer. Thus we must ensure that such insns don't get
266 scheduled across each other because that would invalidate the
267 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
268 wrong, but solving the problem in the scheduler will likely give
269 better code, so we do it here. */
270 static sbitmap reg_known_equiv_p
;
272 /* True when scanning insns from the start of the rtl to the
273 NOTE_INSN_FUNCTION_BEG note. */
274 static bool copying_arguments
;
277 /* The splay-tree used to store the various alias set entries. */
278 static GTY (()) vec
<alias_set_entry
*, va_gc
> *alias_sets
;
280 /* Build a decomposed reference object for querying the alias-oracle
281 from the MEM rtx and store it in *REF.
282 Returns false if MEM is not suitable for the alias-oracle. */
285 ao_ref_from_mem (ao_ref
*ref
, const_rtx mem
)
287 tree expr
= MEM_EXPR (mem
);
293 ao_ref_init (ref
, expr
);
295 /* Get the base of the reference and see if we have to reject or
297 base
= ao_ref_base (ref
);
298 if (base
== NULL_TREE
)
301 /* The tree oracle doesn't like bases that are neither decls
302 nor indirect references of SSA names. */
304 || (TREE_CODE (base
) == MEM_REF
305 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
306 || (TREE_CODE (base
) == TARGET_MEM_REF
307 && TREE_CODE (TMR_BASE (base
)) == SSA_NAME
)))
310 /* If this is a reference based on a partitioned decl replace the
311 base with a MEM_REF of the pointer representative we
312 created during stack slot partitioning. */
314 && ! is_global_var (base
)
315 && cfun
->gimple_df
->decls_to_pointers
!= NULL
)
317 tree
*namep
= cfun
->gimple_df
->decls_to_pointers
->get (base
);
319 ref
->base
= build_simple_mem_ref (*namep
);
322 ref
->ref_alias_set
= MEM_ALIAS_SET (mem
);
324 /* If MEM_OFFSET or MEM_SIZE are unknown what we got from MEM_EXPR
325 is conservative, so trust it. */
326 if (!MEM_OFFSET_KNOWN_P (mem
)
327 || !MEM_SIZE_KNOWN_P (mem
))
330 /* If MEM_OFFSET/MEM_SIZE get us outside of ref->offset/ref->max_size
332 if (maybe_lt (MEM_OFFSET (mem
), 0)
333 || (ref
->max_size_known_p ()
334 && maybe_gt ((MEM_OFFSET (mem
) + MEM_SIZE (mem
)) * BITS_PER_UNIT
,
336 ref
->ref
= NULL_TREE
;
338 /* Refine size and offset we got from analyzing MEM_EXPR by using
339 MEM_SIZE and MEM_OFFSET. */
341 ref
->offset
+= MEM_OFFSET (mem
) * BITS_PER_UNIT
;
342 ref
->size
= MEM_SIZE (mem
) * BITS_PER_UNIT
;
344 /* The MEM may extend into adjacent fields, so adjust max_size if
346 if (ref
->max_size_known_p ())
347 ref
->max_size
= upper_bound (ref
->max_size
, ref
->size
);
349 /* If MEM_OFFSET and MEM_SIZE might get us outside of the base object of
350 the MEM_EXPR punt. This happens for STRICT_ALIGNMENT targets a lot. */
351 if (MEM_EXPR (mem
) != get_spill_slot_decl (false)
352 && (maybe_lt (ref
->offset
, 0)
353 || (DECL_P (ref
->base
)
354 && (DECL_SIZE (ref
->base
) == NULL_TREE
355 || !poly_int_tree_p (DECL_SIZE (ref
->base
))
356 || maybe_lt (wi::to_poly_offset (DECL_SIZE (ref
->base
)),
357 ref
->offset
+ ref
->size
)))))
363 /* Query the alias-oracle on whether the two memory rtx X and MEM may
364 alias. If TBAA_P is set also apply TBAA. Returns true if the
365 two rtxen may alias, false otherwise. */
368 rtx_refs_may_alias_p (const_rtx x
, const_rtx mem
, bool tbaa_p
)
372 if (!ao_ref_from_mem (&ref1
, x
)
373 || !ao_ref_from_mem (&ref2
, mem
))
376 return refs_may_alias_p_1 (&ref1
, &ref2
,
378 && MEM_ALIAS_SET (x
) != 0
379 && MEM_ALIAS_SET (mem
) != 0);
382 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
383 such an entry, or NULL otherwise. */
385 static inline alias_set_entry
*
386 get_alias_set_entry (alias_set_type alias_set
)
388 return (*alias_sets
)[alias_set
];
391 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
392 the two MEMs cannot alias each other. */
395 mems_in_disjoint_alias_sets_p (const_rtx mem1
, const_rtx mem2
)
397 return (flag_strict_aliasing
398 && ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1
),
399 MEM_ALIAS_SET (mem2
)));
402 /* Return true if the first alias set is a subset of the second. */
405 alias_set_subset_of (alias_set_type set1
, alias_set_type set2
)
407 alias_set_entry
*ase2
;
409 /* Disable TBAA oracle with !flag_strict_aliasing. */
410 if (!flag_strict_aliasing
)
413 /* Everything is a subset of the "aliases everything" set. */
417 /* Check if set1 is a subset of set2. */
418 ase2
= get_alias_set_entry (set2
);
420 && (ase2
->has_zero_child
421 || (ase2
->children
&& ase2
->children
->get (set1
))))
424 /* As a special case we consider alias set of "void *" to be both subset
425 and superset of every alias set of a pointer. This extra symmetry does
426 not matter for alias_sets_conflict_p but it makes aliasing_component_refs_p
427 to return true on the following testcase:
430 char **ptr2=(char **)&ptr;
433 Additionally if a set contains universal pointer, we consider every pointer
434 to be a subset of it, but we do not represent this explicitely - doing so
435 would require us to update transitive closure each time we introduce new
436 pointer type. This makes aliasing_component_refs_p to return true
437 on the following testcase:
439 struct a {void *ptr;}
440 char **ptr = (char **)&a.ptr;
443 This makes void * truly universal pointer type. See pointer handling in
444 get_alias_set for more details. */
445 if (ase2
&& ase2
->has_pointer
)
447 alias_set_entry
*ase1
= get_alias_set_entry (set1
);
449 if (ase1
&& ase1
->is_pointer
)
451 alias_set_type voidptr_set
= TYPE_ALIAS_SET (ptr_type_node
);
452 /* If one is ptr_type_node and other is pointer, then we consider
453 them subset of each other. */
454 if (set1
== voidptr_set
|| set2
== voidptr_set
)
456 /* If SET2 contains universal pointer's alias set, then we consdier
457 every (non-universal) pointer. */
458 if (ase2
->children
&& set1
!= voidptr_set
459 && ase2
->children
->get (voidptr_set
))
466 /* Return 1 if the two specified alias sets may conflict. */
469 alias_sets_conflict_p (alias_set_type set1
, alias_set_type set2
)
471 alias_set_entry
*ase1
;
472 alias_set_entry
*ase2
;
475 if (alias_sets_must_conflict_p (set1
, set2
))
478 /* See if the first alias set is a subset of the second. */
479 ase1
= get_alias_set_entry (set1
);
481 && ase1
->children
&& ase1
->children
->get (set2
))
483 ++alias_stats
.num_dag
;
487 /* Now do the same, but with the alias sets reversed. */
488 ase2
= get_alias_set_entry (set2
);
490 && ase2
->children
&& ase2
->children
->get (set1
))
492 ++alias_stats
.num_dag
;
496 /* We want void * to be compatible with any other pointer without
497 really dropping it to alias set 0. Doing so would make it
498 compatible with all non-pointer types too.
500 This is not strictly necessary by the C/C++ language
501 standards, but avoids common type punning mistakes. In
502 addition to that, we need the existence of such universal
503 pointer to implement Fortran's C_PTR type (which is defined as
504 type compatible with all C pointers). */
505 if (ase1
&& ase2
&& ase1
->has_pointer
&& ase2
->has_pointer
)
507 alias_set_type voidptr_set
= TYPE_ALIAS_SET (ptr_type_node
);
509 /* If one of the sets corresponds to universal pointer,
510 we consider it to conflict with anything that is
511 or contains pointer. */
512 if (set1
== voidptr_set
|| set2
== voidptr_set
)
514 ++alias_stats
.num_universal
;
517 /* If one of sets is (non-universal) pointer and the other
518 contains universal pointer, we also get conflict. */
519 if (ase1
->is_pointer
&& set2
!= voidptr_set
520 && ase2
->children
&& ase2
->children
->get (voidptr_set
))
522 ++alias_stats
.num_universal
;
525 if (ase2
->is_pointer
&& set1
!= voidptr_set
526 && ase1
->children
&& ase1
->children
->get (voidptr_set
))
528 ++alias_stats
.num_universal
;
533 ++alias_stats
.num_disambiguated
;
535 /* The two alias sets are distinct and neither one is the
536 child of the other. Therefore, they cannot conflict. */
540 /* Return 1 if the two specified alias sets will always conflict. */
543 alias_sets_must_conflict_p (alias_set_type set1
, alias_set_type set2
)
545 /* Disable TBAA oracle with !flag_strict_aliasing. */
546 if (!flag_strict_aliasing
)
548 if (set1
== 0 || set2
== 0)
550 ++alias_stats
.num_alias_zero
;
555 ++alias_stats
.num_same_alias_set
;
562 /* Return 1 if any MEM object of type T1 will always conflict (using the
563 dependency routines in this file) with any MEM object of type T2.
564 This is used when allocating temporary storage. If T1 and/or T2 are
565 NULL_TREE, it means we know nothing about the storage. */
568 objects_must_conflict_p (tree t1
, tree t2
)
570 alias_set_type set1
, set2
;
572 /* If neither has a type specified, we don't know if they'll conflict
573 because we may be using them to store objects of various types, for
574 example the argument and local variables areas of inlined functions. */
575 if (t1
== 0 && t2
== 0)
578 /* If they are the same type, they must conflict. */
581 ++alias_stats
.num_same_objects
;
584 /* Likewise if both are volatile. */
585 if (t1
!= 0 && TYPE_VOLATILE (t1
) && t2
!= 0 && TYPE_VOLATILE (t2
))
587 ++alias_stats
.num_volatile
;
591 set1
= t1
? get_alias_set (t1
) : 0;
592 set2
= t2
? get_alias_set (t2
) : 0;
594 /* We can't use alias_sets_conflict_p because we must make sure
595 that every subtype of t1 will conflict with every subtype of
596 t2 for which a pair of subobjects of these respective subtypes
597 overlaps on the stack. */
598 return alias_sets_must_conflict_p (set1
, set2
);
601 /* Return the outermost parent of component present in the chain of
602 component references handled by get_inner_reference in T with the
604 - the component is non-addressable
605 or NULL_TREE if no such parent exists. In the former cases, the alias
606 set of this parent is the alias set that must be used for T itself. */
609 component_uses_parent_alias_set_from (const_tree t
)
611 const_tree found
= NULL_TREE
;
613 while (handled_component_p (t
))
615 switch (TREE_CODE (t
))
618 if (DECL_NONADDRESSABLE_P (TREE_OPERAND (t
, 1)))
620 /* Permit type-punning when accessing a union, provided the access
621 is directly through the union. For example, this code does not
622 permit taking the address of a union member and then storing
623 through it. Even the type-punning allowed here is a GCC
624 extension, albeit a common and useful one; the C standard says
625 that such accesses have implementation-defined behavior. */
626 else if (TREE_CODE (TREE_TYPE (TREE_OPERAND (t
, 0))) == UNION_TYPE
)
631 case ARRAY_RANGE_REF
:
632 if (TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t
, 0))))
641 case VIEW_CONVERT_EXPR
:
642 /* Bitfields and casts are never addressable. */
650 t
= TREE_OPERAND (t
, 0);
654 return TREE_OPERAND (found
, 0);
660 /* Return whether the pointer-type T effective for aliasing may
661 access everything and thus the reference has to be assigned
665 ref_all_alias_ptr_type_p (const_tree t
)
667 return (TREE_CODE (TREE_TYPE (t
)) == VOID_TYPE
668 || TYPE_REF_CAN_ALIAS_ALL (t
));
671 /* Return the alias set for the memory pointed to by T, which may be
672 either a type or an expression. Return -1 if there is nothing
673 special about dereferencing T. */
675 static alias_set_type
676 get_deref_alias_set_1 (tree t
)
678 /* All we care about is the type. */
682 /* If we have an INDIRECT_REF via a void pointer, we don't
683 know anything about what that might alias. Likewise if the
684 pointer is marked that way. */
685 if (ref_all_alias_ptr_type_p (t
))
691 /* Return the alias set for the memory pointed to by T, which may be
692 either a type or an expression. */
695 get_deref_alias_set (tree t
)
697 /* If we're not doing any alias analysis, just assume everything
698 aliases everything else. */
699 if (!flag_strict_aliasing
)
702 alias_set_type set
= get_deref_alias_set_1 (t
);
704 /* Fall back to the alias-set of the pointed-to type. */
709 set
= get_alias_set (TREE_TYPE (t
));
715 /* Return the pointer-type relevant for TBAA purposes from the
716 memory reference tree *T or NULL_TREE in which case *T is
717 adjusted to point to the outermost component reference that
718 can be used for assigning an alias set. */
721 reference_alias_ptr_type_1 (tree
*t
)
725 /* Get the base object of the reference. */
727 while (handled_component_p (inner
))
729 /* If there is a VIEW_CONVERT_EXPR in the chain we cannot use
730 the type of any component references that wrap it to
731 determine the alias-set. */
732 if (TREE_CODE (inner
) == VIEW_CONVERT_EXPR
)
733 *t
= TREE_OPERAND (inner
, 0);
734 inner
= TREE_OPERAND (inner
, 0);
737 /* Handle pointer dereferences here, they can override the
739 if (INDIRECT_REF_P (inner
)
740 && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner
, 0))))
741 return TREE_TYPE (TREE_OPERAND (inner
, 0));
742 else if (TREE_CODE (inner
) == TARGET_MEM_REF
)
743 return TREE_TYPE (TMR_OFFSET (inner
));
744 else if (TREE_CODE (inner
) == MEM_REF
745 && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner
, 1))))
746 return TREE_TYPE (TREE_OPERAND (inner
, 1));
748 /* If the innermost reference is a MEM_REF that has a
749 conversion embedded treat it like a VIEW_CONVERT_EXPR above,
750 using the memory access type for determining the alias-set. */
751 if (TREE_CODE (inner
) == MEM_REF
752 && (TYPE_MAIN_VARIANT (TREE_TYPE (inner
))
754 (TREE_TYPE (TREE_TYPE (TREE_OPERAND (inner
, 1))))))
755 return TREE_TYPE (TREE_OPERAND (inner
, 1));
757 /* Otherwise, pick up the outermost object that we could have
759 tree tem
= component_uses_parent_alias_set_from (*t
);
766 /* Return the pointer-type relevant for TBAA purposes from the
767 gimple memory reference tree T. This is the type to be used for
768 the offset operand of MEM_REF or TARGET_MEM_REF replacements of T
769 and guarantees that get_alias_set will return the same alias
770 set for T and the replacement. */
773 reference_alias_ptr_type (tree t
)
775 /* If the frontend assigns this alias-set zero, preserve that. */
776 if (lang_hooks
.get_alias_set (t
) == 0)
777 return ptr_type_node
;
779 tree ptype
= reference_alias_ptr_type_1 (&t
);
780 /* If there is a given pointer type for aliasing purposes, return it. */
781 if (ptype
!= NULL_TREE
)
784 /* Otherwise build one from the outermost component reference we
786 if (TREE_CODE (t
) == MEM_REF
787 || TREE_CODE (t
) == TARGET_MEM_REF
)
788 return TREE_TYPE (TREE_OPERAND (t
, 1));
790 return build_pointer_type (TYPE_MAIN_VARIANT (TREE_TYPE (t
)));
793 /* Return whether the pointer-types T1 and T2 used to determine
794 two alias sets of two references will yield the same answer
795 from get_deref_alias_set. */
798 alias_ptr_types_compatible_p (tree t1
, tree t2
)
800 if (TYPE_MAIN_VARIANT (t1
) == TYPE_MAIN_VARIANT (t2
))
803 if (ref_all_alias_ptr_type_p (t1
)
804 || ref_all_alias_ptr_type_p (t2
))
807 return (TYPE_MAIN_VARIANT (TREE_TYPE (t1
))
808 == TYPE_MAIN_VARIANT (TREE_TYPE (t2
)));
811 /* Create emptry alias set entry. */
814 init_alias_set_entry (alias_set_type set
)
816 alias_set_entry
*ase
= ggc_alloc
<alias_set_entry
> ();
817 ase
->alias_set
= set
;
818 ase
->children
= NULL
;
819 ase
->has_zero_child
= false;
820 ase
->is_pointer
= false;
821 ase
->has_pointer
= false;
822 gcc_checking_assert (!get_alias_set_entry (set
));
823 (*alias_sets
)[set
] = ase
;
827 /* Return the alias set for T, which may be either a type or an
828 expression. Call language-specific routine for help, if needed. */
831 get_alias_set (tree t
)
835 /* We cannot give up with -fno-strict-aliasing because we need to build
836 proper type representation for possible functions which are build with
837 -fstrict-aliasing. */
839 /* return 0 if this or its type is an error. */
840 if (t
== error_mark_node
842 && (TREE_TYPE (t
) == 0 || TREE_TYPE (t
) == error_mark_node
)))
845 /* We can be passed either an expression or a type. This and the
846 language-specific routine may make mutually-recursive calls to each other
847 to figure out what to do. At each juncture, we see if this is a tree
848 that the language may need to handle specially. First handle things that
852 /* Give the language a chance to do something with this tree
853 before we look at it. */
855 set
= lang_hooks
.get_alias_set (t
);
859 /* Get the alias pointer-type to use or the outermost object
860 that we could have a pointer to. */
861 tree ptype
= reference_alias_ptr_type_1 (&t
);
863 return get_deref_alias_set (ptype
);
865 /* If we've already determined the alias set for a decl, just return
866 it. This is necessary for C++ anonymous unions, whose component
867 variables don't look like union members (boo!). */
869 && DECL_RTL_SET_P (t
) && MEM_P (DECL_RTL (t
)))
870 return MEM_ALIAS_SET (DECL_RTL (t
));
872 /* Now all we care about is the type. */
876 /* Variant qualifiers don't affect the alias set, so get the main
878 t
= TYPE_MAIN_VARIANT (t
);
880 if (AGGREGATE_TYPE_P (t
)
881 && TYPE_TYPELESS_STORAGE (t
))
884 /* Always use the canonical type as well. If this is a type that
885 requires structural comparisons to identify compatible types
886 use alias set zero. */
887 if (TYPE_STRUCTURAL_EQUALITY_P (t
))
889 /* Allow the language to specify another alias set for this
891 set
= lang_hooks
.get_alias_set (t
);
894 /* Handle structure type equality for pointer types, arrays and vectors.
895 This is easy to do, because the code bellow ignore canonical types on
896 these anyway. This is important for LTO, where TYPE_CANONICAL for
897 pointers cannot be meaningfuly computed by the frotnend. */
898 if (canonical_type_used_p (t
))
900 /* In LTO we set canonical types for all types where it makes
901 sense to do so. Double check we did not miss some type. */
902 gcc_checking_assert (!in_lto_p
|| !type_with_alias_set_p (t
));
908 t
= TYPE_CANONICAL (t
);
909 gcc_checking_assert (!TYPE_STRUCTURAL_EQUALITY_P (t
));
912 /* If this is a type with a known alias set, return it. */
913 gcc_checking_assert (t
== TYPE_MAIN_VARIANT (t
));
914 if (TYPE_ALIAS_SET_KNOWN_P (t
))
915 return TYPE_ALIAS_SET (t
);
917 /* We don't want to set TYPE_ALIAS_SET for incomplete types. */
918 if (!COMPLETE_TYPE_P (t
))
920 /* For arrays with unknown size the conservative answer is the
921 alias set of the element type. */
922 if (TREE_CODE (t
) == ARRAY_TYPE
)
923 return get_alias_set (TREE_TYPE (t
));
925 /* But return zero as a conservative answer for incomplete types. */
929 /* See if the language has special handling for this type. */
930 set
= lang_hooks
.get_alias_set (t
);
934 /* There are no objects of FUNCTION_TYPE, so there's no point in
935 using up an alias set for them. (There are, of course, pointers
936 and references to functions, but that's different.) */
937 else if (TREE_CODE (t
) == FUNCTION_TYPE
|| TREE_CODE (t
) == METHOD_TYPE
)
940 /* Unless the language specifies otherwise, let vector types alias
941 their components. This avoids some nasty type punning issues in
942 normal usage. And indeed lets vectors be treated more like an
944 else if (TREE_CODE (t
) == VECTOR_TYPE
)
945 set
= get_alias_set (TREE_TYPE (t
));
947 /* Unless the language specifies otherwise, treat array types the
948 same as their components. This avoids the asymmetry we get
949 through recording the components. Consider accessing a
950 character(kind=1) through a reference to a character(kind=1)[1:1].
951 Or consider if we want to assign integer(kind=4)[0:D.1387] and
952 integer(kind=4)[4] the same alias set or not.
953 Just be pragmatic here and make sure the array and its element
954 type get the same alias set assigned. */
955 else if (TREE_CODE (t
) == ARRAY_TYPE
956 && (!TYPE_NONALIASED_COMPONENT (t
)
957 || TYPE_STRUCTURAL_EQUALITY_P (t
)))
958 set
= get_alias_set (TREE_TYPE (t
));
960 /* From the former common C and C++ langhook implementation:
962 Unfortunately, there is no canonical form of a pointer type.
963 In particular, if we have `typedef int I', then `int *', and
964 `I *' are different types. So, we have to pick a canonical
965 representative. We do this below.
967 Technically, this approach is actually more conservative that
968 it needs to be. In particular, `const int *' and `int *'
969 should be in different alias sets, according to the C and C++
970 standard, since their types are not the same, and so,
971 technically, an `int **' and `const int **' cannot point at
974 But, the standard is wrong. In particular, this code is
979 const int* const* cipp = ipp;
980 And, it doesn't make sense for that to be legal unless you
981 can dereference IPP and CIPP. So, we ignore cv-qualifiers on
982 the pointed-to types. This issue has been reported to the
985 For this reason go to canonical type of the unqalified pointer type.
986 Until GCC 6 this code set all pointers sets to have alias set of
987 ptr_type_node but that is a bad idea, because it prevents disabiguations
988 in between pointers. For Firefox this accounts about 20% of all
989 disambiguations in the program. */
990 else if (POINTER_TYPE_P (t
) && t
!= ptr_type_node
)
993 auto_vec
<bool, 8> reference
;
995 /* Unnest all pointers and references.
996 We also want to make pointer to array/vector equivalent to pointer to
997 its element (see the reasoning above). Skip all those types, too. */
998 for (p
= t
; POINTER_TYPE_P (p
)
999 || (TREE_CODE (p
) == ARRAY_TYPE
1000 && (!TYPE_NONALIASED_COMPONENT (p
)
1001 || !COMPLETE_TYPE_P (p
)
1002 || TYPE_STRUCTURAL_EQUALITY_P (p
)))
1003 || TREE_CODE (p
) == VECTOR_TYPE
;
1006 /* Ada supports recusive pointers. Instead of doing recrusion check
1007 just give up once the preallocated space of 8 elements is up.
1008 In this case just punt to void * alias set. */
1009 if (reference
.length () == 8)
1014 if (TREE_CODE (p
) == REFERENCE_TYPE
)
1015 /* In LTO we want languages that use references to be compatible
1016 with languages that use pointers. */
1017 reference
.safe_push (true && !in_lto_p
);
1018 if (TREE_CODE (p
) == POINTER_TYPE
)
1019 reference
.safe_push (false);
1021 p
= TYPE_MAIN_VARIANT (p
);
1023 /* Make void * compatible with char * and also void **.
1024 Programs are commonly violating TBAA by this.
1026 We also make void * to conflict with every pointer
1027 (see record_component_aliases) and thus it is safe it to use it for
1028 pointers to types with TYPE_STRUCTURAL_EQUALITY_P. */
1029 if (TREE_CODE (p
) == VOID_TYPE
|| TYPE_STRUCTURAL_EQUALITY_P (p
))
1030 set
= get_alias_set (ptr_type_node
);
1033 /* Rebuild pointer type starting from canonical types using
1034 unqualified pointers and references only. This way all such
1035 pointers will have the same alias set and will conflict with
1038 Most of time we already have pointers or references of a given type.
1039 If not we build new one just to be sure that if someone later
1040 (probably only middle-end can, as we should assign all alias
1041 classes only after finishing translation unit) builds the pointer
1042 type, the canonical type will match. */
1043 p
= TYPE_CANONICAL (p
);
1044 while (!reference
.is_empty ())
1046 if (reference
.pop ())
1047 p
= build_reference_type (p
);
1049 p
= build_pointer_type (p
);
1050 gcc_checking_assert (p
== TYPE_MAIN_VARIANT (p
));
1051 /* build_pointer_type should always return the canonical type.
1052 For LTO TYPE_CANOINCAL may be NULL, because we do not compute
1053 them. Be sure that frontends do not glob canonical types of
1054 pointers in unexpected way and that p == TYPE_CANONICAL (p)
1055 in all other cases. */
1056 gcc_checking_assert (!TYPE_CANONICAL (p
)
1057 || p
== TYPE_CANONICAL (p
));
1060 /* Assign the alias set to both p and t.
1061 We cannot call get_alias_set (p) here as that would trigger
1062 infinite recursion when p == t. In other cases it would just
1063 trigger unnecesary legwork of rebuilding the pointer again. */
1064 gcc_checking_assert (p
== TYPE_MAIN_VARIANT (p
));
1065 if (TYPE_ALIAS_SET_KNOWN_P (p
))
1066 set
= TYPE_ALIAS_SET (p
);
1069 set
= new_alias_set ();
1070 TYPE_ALIAS_SET (p
) = set
;
1074 /* Alias set of ptr_type_node is special and serve as universal pointer which
1075 is TBAA compatible with every other pointer type. Be sure we have the
1076 alias set built even for LTO which otherwise keeps all TYPE_CANONICAL
1077 of pointer types NULL. */
1078 else if (t
== ptr_type_node
)
1079 set
= new_alias_set ();
1081 /* Otherwise make a new alias set for this type. */
1084 /* Each canonical type gets its own alias set, so canonical types
1085 shouldn't form a tree. It doesn't really matter for types
1086 we handle specially above, so only check it where it possibly
1087 would result in a bogus alias set. */
1088 gcc_checking_assert (TYPE_CANONICAL (t
) == t
);
1090 set
= new_alias_set ();
1093 TYPE_ALIAS_SET (t
) = set
;
1095 /* If this is an aggregate type or a complex type, we must record any
1096 component aliasing information. */
1097 if (AGGREGATE_TYPE_P (t
) || TREE_CODE (t
) == COMPLEX_TYPE
)
1098 record_component_aliases (t
);
1100 /* We treat pointer types specially in alias_set_subset_of. */
1101 if (POINTER_TYPE_P (t
) && set
)
1103 alias_set_entry
*ase
= get_alias_set_entry (set
);
1105 ase
= init_alias_set_entry (set
);
1106 ase
->is_pointer
= true;
1107 ase
->has_pointer
= true;
1113 /* Return a brand-new alias set. */
1116 new_alias_set (void)
1118 if (alias_sets
== 0)
1119 vec_safe_push (alias_sets
, (alias_set_entry
*) NULL
);
1120 vec_safe_push (alias_sets
, (alias_set_entry
*) NULL
);
1121 return alias_sets
->length () - 1;
1124 /* Indicate that things in SUBSET can alias things in SUPERSET, but that
1125 not everything that aliases SUPERSET also aliases SUBSET. For example,
1126 in C, a store to an `int' can alias a load of a structure containing an
1127 `int', and vice versa. But it can't alias a load of a 'double' member
1128 of the same structure. Here, the structure would be the SUPERSET and
1129 `int' the SUBSET. This relationship is also described in the comment at
1130 the beginning of this file.
1132 This function should be called only once per SUPERSET/SUBSET pair.
1134 It is illegal for SUPERSET to be zero; everything is implicitly a
1135 subset of alias set zero. */
1138 record_alias_subset (alias_set_type superset
, alias_set_type subset
)
1140 alias_set_entry
*superset_entry
;
1141 alias_set_entry
*subset_entry
;
1143 /* It is possible in complex type situations for both sets to be the same,
1144 in which case we can ignore this operation. */
1145 if (superset
== subset
)
1148 gcc_assert (superset
);
1150 superset_entry
= get_alias_set_entry (superset
);
1151 if (superset_entry
== 0)
1153 /* Create an entry for the SUPERSET, so that we have a place to
1154 attach the SUBSET. */
1155 superset_entry
= init_alias_set_entry (superset
);
1159 superset_entry
->has_zero_child
= 1;
1162 subset_entry
= get_alias_set_entry (subset
);
1163 if (!superset_entry
->children
)
1164 superset_entry
->children
1165 = hash_map
<alias_set_hash
, int>::create_ggc (64);
1166 /* If there is an entry for the subset, enter all of its children
1167 (if they are not already present) as children of the SUPERSET. */
1170 if (subset_entry
->has_zero_child
)
1171 superset_entry
->has_zero_child
= true;
1172 if (subset_entry
->has_pointer
)
1173 superset_entry
->has_pointer
= true;
1175 if (subset_entry
->children
)
1177 hash_map
<alias_set_hash
, int>::iterator iter
1178 = subset_entry
->children
->begin ();
1179 for (; iter
!= subset_entry
->children
->end (); ++iter
)
1180 superset_entry
->children
->put ((*iter
).first
, (*iter
).second
);
1184 /* Enter the SUBSET itself as a child of the SUPERSET. */
1185 superset_entry
->children
->put (subset
, 0);
1189 /* Record that component types of TYPE, if any, are part of SUPERSET for
1190 aliasing purposes. For record types, we only record component types
1191 for fields that are not marked non-addressable. For array types, we
1192 only record the component type if it is not marked non-aliased. */
1195 record_component_aliases (tree type
, alias_set_type superset
)
1202 switch (TREE_CODE (type
))
1206 case QUAL_UNION_TYPE
:
1207 for (field
= TYPE_FIELDS (type
); field
!= 0; field
= DECL_CHAIN (field
))
1208 if (TREE_CODE (field
) == FIELD_DECL
&& !DECL_NONADDRESSABLE_P (field
))
1210 /* LTO type merging does not make any difference between
1211 component pointer types. We may have
1213 struct foo {int *a;};
1215 as TYPE_CANONICAL of
1217 struct bar {float *a;};
1219 Because accesses to int * and float * do not alias, we would get
1220 false negative when accessing the same memory location by
1221 float ** and bar *. We thus record the canonical type as:
1225 void * is special cased and works as a universal pointer type.
1226 Accesses to it conflicts with accesses to any other pointer
1228 tree t
= TREE_TYPE (field
);
1231 /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their
1232 element type and that type has to be normalized to void *,
1233 too, in the case it is a pointer. */
1234 while (!canonical_type_used_p (t
) && !POINTER_TYPE_P (t
))
1236 gcc_checking_assert (TYPE_STRUCTURAL_EQUALITY_P (t
));
1239 if (POINTER_TYPE_P (t
))
1241 else if (flag_checking
)
1242 gcc_checking_assert (get_alias_set (t
)
1243 == get_alias_set (TREE_TYPE (field
)));
1246 alias_set_type set
= get_alias_set (t
);
1247 record_alias_subset (superset
, set
);
1248 /* If the field has alias-set zero make sure to still record
1249 any componets of it. This makes sure that for
1256 in C++ even though 'B' has alias-set zero because
1257 TYPE_TYPELESS_STORAGE is set, 'A' has the alias-set of
1260 record_component_aliases (t
, superset
);
1265 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
1268 /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their
1276 /* Record that component types of TYPE, if any, are part of that type for
1277 aliasing purposes. For record types, we only record component types
1278 for fields that are not marked non-addressable. For array types, we
1279 only record the component type if it is not marked non-aliased. */
1282 record_component_aliases (tree type
)
1284 alias_set_type superset
= get_alias_set (type
);
1285 record_component_aliases (type
, superset
);
1289 /* Allocate an alias set for use in storing and reading from the varargs
1292 static GTY(()) alias_set_type varargs_set
= -1;
1295 get_varargs_alias_set (void)
1298 /* We now lower VA_ARG_EXPR, and there's currently no way to attach the
1299 varargs alias set to an INDIRECT_REF (FIXME!), so we can't
1300 consistently use the varargs alias set for loads from the varargs
1301 area. So don't use it anywhere. */
1304 if (varargs_set
== -1)
1305 varargs_set
= new_alias_set ();
1311 /* Likewise, but used for the fixed portions of the frame, e.g., register
1314 static GTY(()) alias_set_type frame_set
= -1;
1317 get_frame_alias_set (void)
1319 if (frame_set
== -1)
1320 frame_set
= new_alias_set ();
1325 /* Create a new, unique base with id ID. */
1328 unique_base_value (HOST_WIDE_INT id
)
1330 return gen_rtx_ADDRESS (Pmode
, id
);
1333 /* Return true if accesses based on any other base value cannot alias
1334 those based on X. */
1337 unique_base_value_p (rtx x
)
1339 return GET_CODE (x
) == ADDRESS
&& GET_MODE (x
) == Pmode
;
1342 /* Return true if X is known to be a base value. */
1345 known_base_value_p (rtx x
)
1347 switch (GET_CODE (x
))
1354 /* Arguments may or may not be bases; we don't know for sure. */
1355 return GET_MODE (x
) != VOIDmode
;
1362 /* Inside SRC, the source of a SET, find a base address. */
1365 find_base_value (rtx src
)
1368 scalar_int_mode int_mode
;
1370 #if defined (FIND_BASE_TERM)
1371 /* Try machine-dependent ways to find the base term. */
1372 src
= FIND_BASE_TERM (src
);
1375 switch (GET_CODE (src
))
1382 regno
= REGNO (src
);
1383 /* At the start of a function, argument registers have known base
1384 values which may be lost later. Returning an ADDRESS
1385 expression here allows optimization based on argument values
1386 even when the argument registers are used for other purposes. */
1387 if (regno
< FIRST_PSEUDO_REGISTER
&& copying_arguments
)
1388 return new_reg_base_value
[regno
];
1390 /* If a pseudo has a known base value, return it. Do not do this
1391 for non-fixed hard regs since it can result in a circular
1392 dependency chain for registers which have values at function entry.
1394 The test above is not sufficient because the scheduler may move
1395 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
1396 if ((regno
>= FIRST_PSEUDO_REGISTER
|| fixed_regs
[regno
])
1397 && regno
< vec_safe_length (reg_base_value
))
1399 /* If we're inside init_alias_analysis, use new_reg_base_value
1400 to reduce the number of relaxation iterations. */
1401 if (new_reg_base_value
&& new_reg_base_value
[regno
]
1402 && DF_REG_DEF_COUNT (regno
) == 1)
1403 return new_reg_base_value
[regno
];
1405 if ((*reg_base_value
)[regno
])
1406 return (*reg_base_value
)[regno
];
1412 /* Check for an argument passed in memory. Only record in the
1413 copying-arguments block; it is too hard to track changes
1415 if (copying_arguments
1416 && (XEXP (src
, 0) == arg_pointer_rtx
1417 || (GET_CODE (XEXP (src
, 0)) == PLUS
1418 && XEXP (XEXP (src
, 0), 0) == arg_pointer_rtx
)))
1419 return arg_base_value
;
1423 src
= XEXP (src
, 0);
1424 if (GET_CODE (src
) != PLUS
&& GET_CODE (src
) != MINUS
)
1432 rtx temp
, src_0
= XEXP (src
, 0), src_1
= XEXP (src
, 1);
1434 /* If either operand is a REG that is a known pointer, then it
1436 if (REG_P (src_0
) && REG_POINTER (src_0
))
1437 return find_base_value (src_0
);
1438 if (REG_P (src_1
) && REG_POINTER (src_1
))
1439 return find_base_value (src_1
);
1441 /* If either operand is a REG, then see if we already have
1442 a known value for it. */
1445 temp
= find_base_value (src_0
);
1452 temp
= find_base_value (src_1
);
1457 /* If either base is named object or a special address
1458 (like an argument or stack reference), then use it for the
1460 if (src_0
!= 0 && known_base_value_p (src_0
))
1463 if (src_1
!= 0 && known_base_value_p (src_1
))
1466 /* Guess which operand is the base address:
1467 If either operand is a symbol, then it is the base. If
1468 either operand is a CONST_INT, then the other is the base. */
1469 if (CONST_INT_P (src_1
) || CONSTANT_P (src_0
))
1470 return find_base_value (src_0
);
1471 else if (CONST_INT_P (src_0
) || CONSTANT_P (src_1
))
1472 return find_base_value (src_1
);
1478 /* The standard form is (lo_sum reg sym) so look only at the
1480 return find_base_value (XEXP (src
, 1));
1483 /* If the second operand is constant set the base
1484 address to the first operand. */
1485 if (CONST_INT_P (XEXP (src
, 1)) && INTVAL (XEXP (src
, 1)) != 0)
1486 return find_base_value (XEXP (src
, 0));
1490 /* As we do not know which address space the pointer is referring to, we can
1491 handle this only if the target does not support different pointer or
1492 address modes depending on the address space. */
1493 if (!target_default_pointer_address_modes_p ())
1495 if (!is_a
<scalar_int_mode
> (GET_MODE (src
), &int_mode
)
1496 || GET_MODE_PRECISION (int_mode
) < GET_MODE_PRECISION (Pmode
))
1506 return find_base_value (XEXP (src
, 0));
1509 case SIGN_EXTEND
: /* used for NT/Alpha pointers */
1510 /* As we do not know which address space the pointer is referring to, we can
1511 handle this only if the target does not support different pointer or
1512 address modes depending on the address space. */
1513 if (!target_default_pointer_address_modes_p ())
1517 rtx temp
= find_base_value (XEXP (src
, 0));
1519 if (temp
!= 0 && CONSTANT_P (temp
))
1520 temp
= convert_memory_address (Pmode
, temp
);
1532 /* Called from init_alias_analysis indirectly through note_stores,
1533 or directly if DEST is a register with a REG_NOALIAS note attached.
1534 SET is null in the latter case. */
1536 /* While scanning insns to find base values, reg_seen[N] is nonzero if
1537 register N has been set in this function. */
1538 static sbitmap reg_seen
;
1541 record_set (rtx dest
, const_rtx set
, void *data ATTRIBUTE_UNUSED
)
1550 regno
= REGNO (dest
);
1552 gcc_checking_assert (regno
< reg_base_value
->length ());
1554 n
= REG_NREGS (dest
);
1559 bitmap_set_bit (reg_seen
, regno
+ n
);
1560 new_reg_base_value
[regno
+ n
] = 0;
1567 /* A CLOBBER wipes out any old value but does not prevent a previously
1568 unset register from acquiring a base address (i.e. reg_seen is not
1570 if (GET_CODE (set
) == CLOBBER
)
1572 new_reg_base_value
[regno
] = 0;
1575 /* A CLOBBER_HIGH only wipes out the old value if the mode of the old
1576 value is greater than that of the clobber. */
1577 else if (GET_CODE (set
) == CLOBBER_HIGH
)
1579 if (new_reg_base_value
[regno
] != 0
1580 && reg_is_clobbered_by_clobber_high (
1581 regno
, GET_MODE (new_reg_base_value
[regno
]), XEXP (set
, 0)))
1582 new_reg_base_value
[regno
] = 0;
1586 src
= SET_SRC (set
);
1590 /* There's a REG_NOALIAS note against DEST. */
1591 if (bitmap_bit_p (reg_seen
, regno
))
1593 new_reg_base_value
[regno
] = 0;
1596 bitmap_set_bit (reg_seen
, regno
);
1597 new_reg_base_value
[regno
] = unique_base_value (unique_id
++);
1601 /* If this is not the first set of REGNO, see whether the new value
1602 is related to the old one. There are two cases of interest:
1604 (1) The register might be assigned an entirely new value
1605 that has the same base term as the original set.
1607 (2) The set might be a simple self-modification that
1608 cannot change REGNO's base value.
1610 If neither case holds, reject the original base value as invalid.
1611 Note that the following situation is not detected:
1613 extern int x, y; int *p = &x; p += (&y-&x);
1615 ANSI C does not allow computing the difference of addresses
1616 of distinct top level objects. */
1617 if (new_reg_base_value
[regno
] != 0
1618 && find_base_value (src
) != new_reg_base_value
[regno
])
1619 switch (GET_CODE (src
))
1623 if (XEXP (src
, 0) != dest
&& XEXP (src
, 1) != dest
)
1624 new_reg_base_value
[regno
] = 0;
1627 /* If the value we add in the PLUS is also a valid base value,
1628 this might be the actual base value, and the original value
1631 rtx other
= NULL_RTX
;
1633 if (XEXP (src
, 0) == dest
)
1634 other
= XEXP (src
, 1);
1635 else if (XEXP (src
, 1) == dest
)
1636 other
= XEXP (src
, 0);
1638 if (! other
|| find_base_value (other
))
1639 new_reg_base_value
[regno
] = 0;
1643 if (XEXP (src
, 0) != dest
|| !CONST_INT_P (XEXP (src
, 1)))
1644 new_reg_base_value
[regno
] = 0;
1647 new_reg_base_value
[regno
] = 0;
1650 /* If this is the first set of a register, record the value. */
1651 else if ((regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
1652 && ! bitmap_bit_p (reg_seen
, regno
) && new_reg_base_value
[regno
] == 0)
1653 new_reg_base_value
[regno
] = find_base_value (src
);
1655 bitmap_set_bit (reg_seen
, regno
);
1658 /* Return REG_BASE_VALUE for REGNO. Selective scheduler uses this to avoid
1659 using hard registers with non-null REG_BASE_VALUE for renaming. */
1661 get_reg_base_value (unsigned int regno
)
1663 return (*reg_base_value
)[regno
];
1666 /* If a value is known for REGNO, return it. */
1669 get_reg_known_value (unsigned int regno
)
1671 if (regno
>= FIRST_PSEUDO_REGISTER
)
1673 regno
-= FIRST_PSEUDO_REGISTER
;
1674 if (regno
< vec_safe_length (reg_known_value
))
1675 return (*reg_known_value
)[regno
];
1683 set_reg_known_value (unsigned int regno
, rtx val
)
1685 if (regno
>= FIRST_PSEUDO_REGISTER
)
1687 regno
-= FIRST_PSEUDO_REGISTER
;
1688 if (regno
< vec_safe_length (reg_known_value
))
1689 (*reg_known_value
)[regno
] = val
;
1693 /* Similarly for reg_known_equiv_p. */
1696 get_reg_known_equiv_p (unsigned int regno
)
1698 if (regno
>= FIRST_PSEUDO_REGISTER
)
1700 regno
-= FIRST_PSEUDO_REGISTER
;
1701 if (regno
< vec_safe_length (reg_known_value
))
1702 return bitmap_bit_p (reg_known_equiv_p
, regno
);
1708 set_reg_known_equiv_p (unsigned int regno
, bool val
)
1710 if (regno
>= FIRST_PSEUDO_REGISTER
)
1712 regno
-= FIRST_PSEUDO_REGISTER
;
1713 if (regno
< vec_safe_length (reg_known_value
))
1716 bitmap_set_bit (reg_known_equiv_p
, regno
);
1718 bitmap_clear_bit (reg_known_equiv_p
, regno
);
1724 /* Returns a canonical version of X, from the point of view alias
1725 analysis. (For example, if X is a MEM whose address is a register,
1726 and the register has a known value (say a SYMBOL_REF), then a MEM
1727 whose address is the SYMBOL_REF is returned.) */
1732 /* Recursively look for equivalences. */
1733 if (REG_P (x
) && REGNO (x
) >= FIRST_PSEUDO_REGISTER
)
1735 rtx t
= get_reg_known_value (REGNO (x
));
1739 return canon_rtx (t
);
1742 if (GET_CODE (x
) == PLUS
)
1744 rtx x0
= canon_rtx (XEXP (x
, 0));
1745 rtx x1
= canon_rtx (XEXP (x
, 1));
1747 if (x0
!= XEXP (x
, 0) || x1
!= XEXP (x
, 1))
1748 return simplify_gen_binary (PLUS
, GET_MODE (x
), x0
, x1
);
1751 /* This gives us much better alias analysis when called from
1752 the loop optimizer. Note we want to leave the original
1753 MEM alone, but need to return the canonicalized MEM with
1754 all the flags with their original values. */
1756 x
= replace_equiv_address_nv (x
, canon_rtx (XEXP (x
, 0)));
1761 /* Return 1 if X and Y are identical-looking rtx's.
1762 Expect that X and Y has been already canonicalized.
1764 We use the data in reg_known_value above to see if two registers with
1765 different numbers are, in fact, equivalent. */
1768 rtx_equal_for_memref_p (const_rtx x
, const_rtx y
)
1775 if (x
== 0 && y
== 0)
1777 if (x
== 0 || y
== 0)
1783 code
= GET_CODE (x
);
1784 /* Rtx's of different codes cannot be equal. */
1785 if (code
!= GET_CODE (y
))
1788 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1789 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1791 if (GET_MODE (x
) != GET_MODE (y
))
1794 /* Some RTL can be compared without a recursive examination. */
1798 return REGNO (x
) == REGNO (y
);
1801 return label_ref_label (x
) == label_ref_label (y
);
1804 return compare_base_symbol_refs (x
, y
) == 1;
1807 /* This is magic, don't go through canonicalization et al. */
1808 return rtx_equal_p (ENTRY_VALUE_EXP (x
), ENTRY_VALUE_EXP (y
));
1812 /* Pointer equality guarantees equality for these nodes. */
1819 /* canon_rtx knows how to handle plus. No need to canonicalize. */
1821 return ((rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0))
1822 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 1)))
1823 || (rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 1))
1824 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 0))));
1825 /* For commutative operations, the RTX match if the operand match in any
1826 order. Also handle the simple binary and unary cases without a loop. */
1827 if (COMMUTATIVE_P (x
))
1829 rtx xop0
= canon_rtx (XEXP (x
, 0));
1830 rtx yop0
= canon_rtx (XEXP (y
, 0));
1831 rtx yop1
= canon_rtx (XEXP (y
, 1));
1833 return ((rtx_equal_for_memref_p (xop0
, yop0
)
1834 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop1
))
1835 || (rtx_equal_for_memref_p (xop0
, yop1
)
1836 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop0
)));
1838 else if (NON_COMMUTATIVE_P (x
))
1840 return (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1841 canon_rtx (XEXP (y
, 0)))
1842 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)),
1843 canon_rtx (XEXP (y
, 1))));
1845 else if (UNARY_P (x
))
1846 return rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1847 canon_rtx (XEXP (y
, 0)));
1849 /* Compare the elements. If any pair of corresponding elements
1850 fail to match, return 0 for the whole things.
1852 Limit cases to types which actually appear in addresses. */
1854 fmt
= GET_RTX_FORMAT (code
);
1855 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1860 if (XINT (x
, i
) != XINT (y
, i
))
1865 if (maybe_ne (SUBREG_BYTE (x
), SUBREG_BYTE (y
)))
1870 /* Two vectors must have the same length. */
1871 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1874 /* And the corresponding elements must match. */
1875 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1876 if (rtx_equal_for_memref_p (canon_rtx (XVECEXP (x
, i
, j
)),
1877 canon_rtx (XVECEXP (y
, i
, j
))) == 0)
1882 if (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, i
)),
1883 canon_rtx (XEXP (y
, i
))) == 0)
1887 /* This can happen for asm operands. */
1889 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1893 /* This can happen for an asm which clobbers memory. */
1897 /* It is believed that rtx's at this level will never
1898 contain anything but integers and other rtx's,
1899 except for within LABEL_REFs and SYMBOL_REFs. */
1908 find_base_term (rtx x
, vec
<std::pair
<cselib_val
*,
1909 struct elt_loc_list
*> > &visited_vals
)
1912 struct elt_loc_list
*l
, *f
;
1914 scalar_int_mode int_mode
;
1916 #if defined (FIND_BASE_TERM)
1917 /* Try machine-dependent ways to find the base term. */
1918 x
= FIND_BASE_TERM (x
);
1921 switch (GET_CODE (x
))
1924 return REG_BASE_VALUE (x
);
1927 /* As we do not know which address space the pointer is referring to, we can
1928 handle this only if the target does not support different pointer or
1929 address modes depending on the address space. */
1930 if (!target_default_pointer_address_modes_p ())
1932 if (!is_a
<scalar_int_mode
> (GET_MODE (x
), &int_mode
)
1933 || GET_MODE_PRECISION (int_mode
) < GET_MODE_PRECISION (Pmode
))
1943 return find_base_term (XEXP (x
, 0), visited_vals
);
1946 case SIGN_EXTEND
: /* Used for Alpha/NT pointers */
1947 /* As we do not know which address space the pointer is referring to, we can
1948 handle this only if the target does not support different pointer or
1949 address modes depending on the address space. */
1950 if (!target_default_pointer_address_modes_p ())
1954 rtx temp
= find_base_term (XEXP (x
, 0), visited_vals
);
1956 if (temp
!= 0 && CONSTANT_P (temp
))
1957 temp
= convert_memory_address (Pmode
, temp
);
1963 val
= CSELIB_VAL_PTR (x
);
1969 if (cselib_sp_based_value_p (val
))
1970 return static_reg_base_value
[STACK_POINTER_REGNUM
];
1973 /* Reset val->locs to avoid infinite recursion. */
1975 visited_vals
.safe_push (std::make_pair (val
, f
));
1978 for (l
= f
; l
; l
= l
->next
)
1979 if (GET_CODE (l
->loc
) == VALUE
1980 && CSELIB_VAL_PTR (l
->loc
)->locs
1981 && !CSELIB_VAL_PTR (l
->loc
)->locs
->next
1982 && CSELIB_VAL_PTR (l
->loc
)->locs
->loc
== x
)
1984 else if ((ret
= find_base_term (l
->loc
, visited_vals
)) != 0)
1990 /* The standard form is (lo_sum reg sym) so look only at the
1992 return find_base_term (XEXP (x
, 1), visited_vals
);
1996 if (GET_CODE (x
) != PLUS
&& GET_CODE (x
) != MINUS
)
2002 rtx tmp1
= XEXP (x
, 0);
2003 rtx tmp2
= XEXP (x
, 1);
2005 /* This is a little bit tricky since we have to determine which of
2006 the two operands represents the real base address. Otherwise this
2007 routine may return the index register instead of the base register.
2009 That may cause us to believe no aliasing was possible, when in
2010 fact aliasing is possible.
2012 We use a few simple tests to guess the base register. Additional
2013 tests can certainly be added. For example, if one of the operands
2014 is a shift or multiply, then it must be the index register and the
2015 other operand is the base register. */
2017 if (tmp1
== pic_offset_table_rtx
&& CONSTANT_P (tmp2
))
2018 return find_base_term (tmp2
, visited_vals
);
2020 /* If either operand is known to be a pointer, then prefer it
2021 to determine the base term. */
2022 if (REG_P (tmp1
) && REG_POINTER (tmp1
))
2024 else if (REG_P (tmp2
) && REG_POINTER (tmp2
))
2025 std::swap (tmp1
, tmp2
);
2026 /* If second argument is constant which has base term, prefer it
2027 over variable tmp1. See PR64025. */
2028 else if (CONSTANT_P (tmp2
) && !CONST_INT_P (tmp2
))
2029 std::swap (tmp1
, tmp2
);
2031 /* Go ahead and find the base term for both operands. If either base
2032 term is from a pointer or is a named object or a special address
2033 (like an argument or stack reference), then use it for the
2035 rtx base
= find_base_term (tmp1
, visited_vals
);
2036 if (base
!= NULL_RTX
2037 && ((REG_P (tmp1
) && REG_POINTER (tmp1
))
2038 || known_base_value_p (base
)))
2040 base
= find_base_term (tmp2
, visited_vals
);
2041 if (base
!= NULL_RTX
2042 && ((REG_P (tmp2
) && REG_POINTER (tmp2
))
2043 || known_base_value_p (base
)))
2046 /* We could not determine which of the two operands was the
2047 base register and which was the index. So we can determine
2048 nothing from the base alias check. */
2053 if (CONST_INT_P (XEXP (x
, 1)) && INTVAL (XEXP (x
, 1)) != 0)
2054 return find_base_term (XEXP (x
, 0), visited_vals
);
2066 /* Wrapper around the worker above which removes locs from visited VALUEs
2067 to avoid visiting them multiple times. We unwind that changes here. */
2070 find_base_term (rtx x
)
2072 auto_vec
<std::pair
<cselib_val
*, struct elt_loc_list
*>, 32> visited_vals
;
2073 rtx res
= find_base_term (x
, visited_vals
);
2074 for (unsigned i
= 0; i
< visited_vals
.length (); ++i
)
2075 visited_vals
[i
].first
->locs
= visited_vals
[i
].second
;
2079 /* Return true if accesses to address X may alias accesses based
2080 on the stack pointer. */
2083 may_be_sp_based_p (rtx x
)
2085 rtx base
= find_base_term (x
);
2086 return !base
|| base
== static_reg_base_value
[STACK_POINTER_REGNUM
];
2089 /* BASE1 and BASE2 are decls. Return 1 if they refer to same object, 0
2090 if they refer to different objects and -1 if we cannot decide. */
2093 compare_base_decls (tree base1
, tree base2
)
2096 gcc_checking_assert (DECL_P (base1
) && DECL_P (base2
));
2100 /* If we have two register decls with register specification we
2101 cannot decide unless their assembler names are the same. */
2102 if (DECL_REGISTER (base1
)
2103 && DECL_REGISTER (base2
)
2104 && HAS_DECL_ASSEMBLER_NAME_P (base1
)
2105 && HAS_DECL_ASSEMBLER_NAME_P (base2
)
2106 && DECL_ASSEMBLER_NAME_SET_P (base1
)
2107 && DECL_ASSEMBLER_NAME_SET_P (base2
))
2109 if (DECL_ASSEMBLER_NAME_RAW (base1
) == DECL_ASSEMBLER_NAME_RAW (base2
))
2114 /* Declarations of non-automatic variables may have aliases. All other
2115 decls are unique. */
2116 if (!decl_in_symtab_p (base1
)
2117 || !decl_in_symtab_p (base2
))
2120 /* Don't cause symbols to be inserted by the act of checking. */
2121 symtab_node
*node1
= symtab_node::get (base1
);
2124 symtab_node
*node2
= symtab_node::get (base2
);
2128 ret
= node1
->equal_address_to (node2
, true);
2132 /* Same as compare_base_decls but for SYMBOL_REF. */
2135 compare_base_symbol_refs (const_rtx x_base
, const_rtx y_base
)
2137 tree x_decl
= SYMBOL_REF_DECL (x_base
);
2138 tree y_decl
= SYMBOL_REF_DECL (y_base
);
2139 bool binds_def
= true;
2141 if (XSTR (x_base
, 0) == XSTR (y_base
, 0))
2143 if (x_decl
&& y_decl
)
2144 return compare_base_decls (x_decl
, y_decl
);
2145 if (x_decl
|| y_decl
)
2149 std::swap (x_decl
, y_decl
);
2150 std::swap (x_base
, y_base
);
2152 /* We handle specially only section anchors and assume that other
2153 labels may overlap with user variables in an arbitrary way. */
2154 if (!SYMBOL_REF_HAS_BLOCK_INFO_P (y_base
))
2156 /* Anchors contains static VAR_DECLs and CONST_DECLs. We are safe
2157 to ignore CONST_DECLs because they are readonly. */
2159 || (!TREE_STATIC (x_decl
) && !TREE_PUBLIC (x_decl
)))
2162 symtab_node
*x_node
= symtab_node::get_create (x_decl
)
2163 ->ultimate_alias_target ();
2164 /* External variable cannot be in section anchor. */
2165 if (!x_node
->definition
)
2167 x_base
= XEXP (DECL_RTL (x_node
->decl
), 0);
2168 /* If not in anchor, we can disambiguate. */
2169 if (!SYMBOL_REF_HAS_BLOCK_INFO_P (x_base
))
2172 /* We have an alias of anchored variable. If it can be interposed;
2173 we must assume it may or may not alias its anchor. */
2174 binds_def
= decl_binds_to_current_def_p (x_decl
);
2176 /* If we have variable in section anchor, we can compare by offset. */
2177 if (SYMBOL_REF_HAS_BLOCK_INFO_P (x_base
)
2178 && SYMBOL_REF_HAS_BLOCK_INFO_P (y_base
))
2180 if (SYMBOL_REF_BLOCK (x_base
) != SYMBOL_REF_BLOCK (y_base
))
2182 if (SYMBOL_REF_BLOCK_OFFSET (x_base
) == SYMBOL_REF_BLOCK_OFFSET (y_base
))
2183 return binds_def
? 1 : -1;
2184 if (SYMBOL_REF_ANCHOR_P (x_base
) != SYMBOL_REF_ANCHOR_P (y_base
))
2188 /* In general we assume that memory locations pointed to by different labels
2189 may overlap in undefined ways. */
2193 /* Return 0 if the addresses X and Y are known to point to different
2194 objects, 1 if they might be pointers to the same object. */
2197 base_alias_check (rtx x
, rtx x_base
, rtx y
, rtx y_base
,
2198 machine_mode x_mode
, machine_mode y_mode
)
2200 /* If the address itself has no known base see if a known equivalent
2201 value has one. If either address still has no known base, nothing
2202 is known about aliasing. */
2207 if (! flag_expensive_optimizations
|| (x_c
= canon_rtx (x
)) == x
)
2210 x_base
= find_base_term (x_c
);
2218 if (! flag_expensive_optimizations
|| (y_c
= canon_rtx (y
)) == y
)
2221 y_base
= find_base_term (y_c
);
2226 /* If the base addresses are equal nothing is known about aliasing. */
2227 if (rtx_equal_p (x_base
, y_base
))
2230 /* The base addresses are different expressions. If they are not accessed
2231 via AND, there is no conflict. We can bring knowledge of object
2232 alignment into play here. For example, on alpha, "char a, b;" can
2233 alias one another, though "char a; long b;" cannot. AND addresses may
2234 implicitly alias surrounding objects; i.e. unaligned access in DImode
2235 via AND address can alias all surrounding object types except those
2236 with aligment 8 or higher. */
2237 if (GET_CODE (x
) == AND
&& GET_CODE (y
) == AND
)
2239 if (GET_CODE (x
) == AND
2240 && (!CONST_INT_P (XEXP (x
, 1))
2241 || (int) GET_MODE_UNIT_SIZE (y_mode
) < -INTVAL (XEXP (x
, 1))))
2243 if (GET_CODE (y
) == AND
2244 && (!CONST_INT_P (XEXP (y
, 1))
2245 || (int) GET_MODE_UNIT_SIZE (x_mode
) < -INTVAL (XEXP (y
, 1))))
2248 /* Differing symbols not accessed via AND never alias. */
2249 if (GET_CODE (x_base
) == SYMBOL_REF
&& GET_CODE (y_base
) == SYMBOL_REF
)
2250 return compare_base_symbol_refs (x_base
, y_base
) != 0;
2252 if (GET_CODE (x_base
) != ADDRESS
&& GET_CODE (y_base
) != ADDRESS
)
2255 if (unique_base_value_p (x_base
) || unique_base_value_p (y_base
))
2261 /* Return TRUE if EXPR refers to a VALUE whose uid is greater than
2262 (or equal to) that of V. */
2265 refs_newer_value_p (const_rtx expr
, rtx v
)
2267 int minuid
= CSELIB_VAL_PTR (v
)->uid
;
2268 subrtx_iterator::array_type array
;
2269 FOR_EACH_SUBRTX (iter
, array
, expr
, NONCONST
)
2270 if (GET_CODE (*iter
) == VALUE
&& CSELIB_VAL_PTR (*iter
)->uid
>= minuid
)
2275 /* Convert the address X into something we can use. This is done by returning
2276 it unchanged unless it is a VALUE or VALUE +/- constant; for VALUE
2277 we call cselib to get a more useful rtx. */
2283 struct elt_loc_list
*l
;
2285 if (GET_CODE (x
) != VALUE
)
2287 if ((GET_CODE (x
) == PLUS
|| GET_CODE (x
) == MINUS
)
2288 && GET_CODE (XEXP (x
, 0)) == VALUE
2289 && CONST_SCALAR_INT_P (XEXP (x
, 1)))
2291 rtx op0
= get_addr (XEXP (x
, 0));
2292 if (op0
!= XEXP (x
, 0))
2295 if (GET_CODE (x
) == PLUS
2296 && poly_int_rtx_p (XEXP (x
, 1), &c
))
2297 return plus_constant (GET_MODE (x
), op0
, c
);
2298 return simplify_gen_binary (GET_CODE (x
), GET_MODE (x
),
2304 v
= CSELIB_VAL_PTR (x
);
2307 bool have_equivs
= cselib_have_permanent_equivalences ();
2309 v
= canonical_cselib_val (v
);
2310 for (l
= v
->locs
; l
; l
= l
->next
)
2311 if (CONSTANT_P (l
->loc
))
2313 for (l
= v
->locs
; l
; l
= l
->next
)
2314 if (!REG_P (l
->loc
) && !MEM_P (l
->loc
)
2315 /* Avoid infinite recursion when potentially dealing with
2316 var-tracking artificial equivalences, by skipping the
2317 equivalences themselves, and not choosing expressions
2318 that refer to newer VALUEs. */
2320 || (GET_CODE (l
->loc
) != VALUE
2321 && !refs_newer_value_p (l
->loc
, x
))))
2325 for (l
= v
->locs
; l
; l
= l
->next
)
2327 || (GET_CODE (l
->loc
) != VALUE
2328 && !refs_newer_value_p (l
->loc
, x
)))
2330 /* Return the canonical value. */
2334 return v
->locs
->loc
;
2339 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
2340 where SIZE is the size in bytes of the memory reference. If ADDR
2341 is not modified by the memory reference then ADDR is returned. */
2344 addr_side_effect_eval (rtx addr
, poly_int64 size
, int n_refs
)
2346 poly_int64 offset
= 0;
2348 switch (GET_CODE (addr
))
2351 offset
= (n_refs
+ 1) * size
;
2354 offset
= -(n_refs
+ 1) * size
;
2357 offset
= n_refs
* size
;
2360 offset
= -n_refs
* size
;
2367 addr
= plus_constant (GET_MODE (addr
), XEXP (addr
, 0), offset
);
2368 addr
= canon_rtx (addr
);
2373 /* Return TRUE if an object X sized at XSIZE bytes and another object
2374 Y sized at YSIZE bytes, starting C bytes after X, may overlap. If
2375 any of the sizes is zero, assume an overlap, otherwise use the
2376 absolute value of the sizes as the actual sizes. */
2379 offset_overlap_p (poly_int64 c
, poly_int64 xsize
, poly_int64 ysize
)
2381 if (known_eq (xsize
, 0) || known_eq (ysize
, 0))
2384 if (maybe_ge (c
, 0))
2385 return maybe_gt (maybe_lt (xsize
, 0) ? -xsize
: xsize
, c
);
2387 return maybe_gt (maybe_lt (ysize
, 0) ? -ysize
: ysize
, -c
);
2390 /* Return one if X and Y (memory addresses) reference the
2391 same location in memory or if the references overlap.
2392 Return zero if they do not overlap, else return
2393 minus one in which case they still might reference the same location.
2395 C is an offset accumulator. When
2396 C is nonzero, we are testing aliases between X and Y + C.
2397 XSIZE is the size in bytes of the X reference,
2398 similarly YSIZE is the size in bytes for Y.
2399 Expect that canon_rtx has been already called for X and Y.
2401 If XSIZE or YSIZE is zero, we do not know the amount of memory being
2402 referenced (the reference was BLKmode), so make the most pessimistic
2405 If XSIZE or YSIZE is negative, we may access memory outside the object
2406 being referenced as a side effect. This can happen when using AND to
2407 align memory references, as is done on the Alpha.
2409 Nice to notice that varying addresses cannot conflict with fp if no
2410 local variables had their addresses taken, but that's too hard now.
2412 ??? Contrary to the tree alias oracle this does not return
2413 one for X + non-constant and Y + non-constant when X and Y are equal.
2414 If that is fixed the TBAA hack for union type-punning can be removed. */
2417 memrefs_conflict_p (poly_int64 xsize
, rtx x
, poly_int64 ysize
, rtx y
,
2420 if (GET_CODE (x
) == VALUE
)
2424 struct elt_loc_list
*l
= NULL
;
2425 if (CSELIB_VAL_PTR (x
))
2426 for (l
= canonical_cselib_val (CSELIB_VAL_PTR (x
))->locs
;
2428 if (REG_P (l
->loc
) && rtx_equal_for_memref_p (l
->loc
, y
))
2435 /* Don't call get_addr if y is the same VALUE. */
2439 if (GET_CODE (y
) == VALUE
)
2443 struct elt_loc_list
*l
= NULL
;
2444 if (CSELIB_VAL_PTR (y
))
2445 for (l
= canonical_cselib_val (CSELIB_VAL_PTR (y
))->locs
;
2447 if (REG_P (l
->loc
) && rtx_equal_for_memref_p (l
->loc
, x
))
2454 /* Don't call get_addr if x is the same VALUE. */
2458 if (GET_CODE (x
) == HIGH
)
2460 else if (GET_CODE (x
) == LO_SUM
)
2463 x
= addr_side_effect_eval (x
, maybe_lt (xsize
, 0) ? -xsize
: xsize
, 0);
2464 if (GET_CODE (y
) == HIGH
)
2466 else if (GET_CODE (y
) == LO_SUM
)
2469 y
= addr_side_effect_eval (y
, maybe_lt (ysize
, 0) ? -ysize
: ysize
, 0);
2471 if (GET_CODE (x
) == SYMBOL_REF
&& GET_CODE (y
) == SYMBOL_REF
)
2473 int cmp
= compare_base_symbol_refs (x
,y
);
2475 /* If both decls are the same, decide by offsets. */
2477 return offset_overlap_p (c
, xsize
, ysize
);
2478 /* Assume a potential overlap for symbolic addresses that went
2479 through alignment adjustments (i.e., that have negative
2480 sizes), because we can't know how far they are from each
2482 if (maybe_lt (xsize
, 0) || maybe_lt (ysize
, 0))
2484 /* If decls are different or we know by offsets that there is no overlap,
2486 if (!cmp
|| !offset_overlap_p (c
, xsize
, ysize
))
2488 /* Decls may or may not be different and offsets overlap....*/
2491 else if (rtx_equal_for_memref_p (x
, y
))
2493 return offset_overlap_p (c
, xsize
, ysize
);
2496 /* This code used to check for conflicts involving stack references and
2497 globals but the base address alias code now handles these cases. */
2499 if (GET_CODE (x
) == PLUS
)
2501 /* The fact that X is canonicalized means that this
2502 PLUS rtx is canonicalized. */
2503 rtx x0
= XEXP (x
, 0);
2504 rtx x1
= XEXP (x
, 1);
2506 /* However, VALUEs might end up in different positions even in
2507 canonical PLUSes. Comparing their addresses is enough. */
2509 return memrefs_conflict_p (xsize
, x1
, ysize
, const0_rtx
, c
);
2511 return memrefs_conflict_p (xsize
, x0
, ysize
, const0_rtx
, c
);
2513 poly_int64 cx1
, cy1
;
2514 if (GET_CODE (y
) == PLUS
)
2516 /* The fact that Y is canonicalized means that this
2517 PLUS rtx is canonicalized. */
2518 rtx y0
= XEXP (y
, 0);
2519 rtx y1
= XEXP (y
, 1);
2522 return memrefs_conflict_p (xsize
, x1
, ysize
, y0
, c
);
2524 return memrefs_conflict_p (xsize
, x0
, ysize
, y1
, c
);
2526 if (rtx_equal_for_memref_p (x1
, y1
))
2527 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
2528 if (rtx_equal_for_memref_p (x0
, y0
))
2529 return memrefs_conflict_p (xsize
, x1
, ysize
, y1
, c
);
2530 if (poly_int_rtx_p (x1
, &cx1
))
2532 if (poly_int_rtx_p (y1
, &cy1
))
2533 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
,
2536 return memrefs_conflict_p (xsize
, x0
, ysize
, y
, c
- cx1
);
2538 else if (poly_int_rtx_p (y1
, &cy1
))
2539 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ cy1
);
2543 else if (poly_int_rtx_p (x1
, &cx1
))
2544 return memrefs_conflict_p (xsize
, x0
, ysize
, y
, c
- cx1
);
2546 else if (GET_CODE (y
) == PLUS
)
2548 /* The fact that Y is canonicalized means that this
2549 PLUS rtx is canonicalized. */
2550 rtx y0
= XEXP (y
, 0);
2551 rtx y1
= XEXP (y
, 1);
2554 return memrefs_conflict_p (xsize
, const0_rtx
, ysize
, y1
, c
);
2556 return memrefs_conflict_p (xsize
, const0_rtx
, ysize
, y0
, c
);
2559 if (poly_int_rtx_p (y1
, &cy1
))
2560 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ cy1
);
2565 if (GET_CODE (x
) == GET_CODE (y
))
2566 switch (GET_CODE (x
))
2570 /* Handle cases where we expect the second operands to be the
2571 same, and check only whether the first operand would conflict
2574 rtx x1
= canon_rtx (XEXP (x
, 1));
2575 rtx y1
= canon_rtx (XEXP (y
, 1));
2576 if (! rtx_equal_for_memref_p (x1
, y1
))
2578 x0
= canon_rtx (XEXP (x
, 0));
2579 y0
= canon_rtx (XEXP (y
, 0));
2580 if (rtx_equal_for_memref_p (x0
, y0
))
2581 return offset_overlap_p (c
, xsize
, ysize
);
2583 /* Can't properly adjust our sizes. */
2585 if (!poly_int_rtx_p (x1
, &c1
)
2586 || !can_div_trunc_p (xsize
, c1
, &xsize
)
2587 || !can_div_trunc_p (ysize
, c1
, &ysize
)
2588 || !can_div_trunc_p (c
, c1
, &c
))
2590 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
2597 /* Deal with alignment ANDs by adjusting offset and size so as to
2598 cover the maximum range, without taking any previously known
2599 alignment into account. Make a size negative after such an
2600 adjustments, so that, if we end up with e.g. two SYMBOL_REFs, we
2601 assume a potential overlap, because they may end up in contiguous
2602 memory locations and the stricter-alignment access may span over
2604 if (GET_CODE (x
) == AND
&& CONST_INT_P (XEXP (x
, 1)))
2606 HOST_WIDE_INT sc
= INTVAL (XEXP (x
, 1));
2607 unsigned HOST_WIDE_INT uc
= sc
;
2608 if (sc
< 0 && pow2_or_zerop (-uc
))
2610 if (maybe_gt (xsize
, 0))
2612 if (maybe_ne (xsize
, 0))
2615 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2619 if (GET_CODE (y
) == AND
&& CONST_INT_P (XEXP (y
, 1)))
2621 HOST_WIDE_INT sc
= INTVAL (XEXP (y
, 1));
2622 unsigned HOST_WIDE_INT uc
= sc
;
2623 if (sc
< 0 && pow2_or_zerop (-uc
))
2625 if (maybe_gt (ysize
, 0))
2627 if (maybe_ne (ysize
, 0))
2630 return memrefs_conflict_p (xsize
, x
,
2631 ysize
, canon_rtx (XEXP (y
, 0)), c
);
2638 if (poly_int_rtx_p (x
, &cx
) && poly_int_rtx_p (y
, &cy
))
2641 return offset_overlap_p (c
, xsize
, ysize
);
2644 if (GET_CODE (x
) == CONST
)
2646 if (GET_CODE (y
) == CONST
)
2647 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2648 ysize
, canon_rtx (XEXP (y
, 0)), c
);
2650 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
2653 if (GET_CODE (y
) == CONST
)
2654 return memrefs_conflict_p (xsize
, x
, ysize
,
2655 canon_rtx (XEXP (y
, 0)), c
);
2657 /* Assume a potential overlap for symbolic addresses that went
2658 through alignment adjustments (i.e., that have negative
2659 sizes), because we can't know how far they are from each
2662 return (maybe_lt (xsize
, 0)
2663 || maybe_lt (ysize
, 0)
2664 || offset_overlap_p (c
, xsize
, ysize
));
2672 /* Functions to compute memory dependencies.
2674 Since we process the insns in execution order, we can build tables
2675 to keep track of what registers are fixed (and not aliased), what registers
2676 are varying in known ways, and what registers are varying in unknown
2679 If both memory references are volatile, then there must always be a
2680 dependence between the two references, since their order cannot be
2681 changed. A volatile and non-volatile reference can be interchanged
2684 We also must allow AND addresses, because they may generate accesses
2685 outside the object being referenced. This is used to generate aligned
2686 addresses from unaligned addresses, for instance, the alpha
2687 storeqi_unaligned pattern. */
2689 /* Read dependence: X is read after read in MEM takes place. There can
2690 only be a dependence here if both reads are volatile, or if either is
2691 an explicit barrier. */
2694 read_dependence (const_rtx mem
, const_rtx x
)
2696 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2698 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2699 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2704 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
2707 decl_for_component_ref (tree x
)
2711 x
= TREE_OPERAND (x
, 0);
2713 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
2715 return x
&& DECL_P (x
) ? x
: NULL_TREE
;
2718 /* Walk up the COMPONENT_REF list in X and adjust *OFFSET to compensate
2719 for the offset of the field reference. *KNOWN_P says whether the
2723 adjust_offset_for_component_ref (tree x
, bool *known_p
,
2730 tree xoffset
= component_ref_field_offset (x
);
2731 tree field
= TREE_OPERAND (x
, 1);
2732 if (!poly_int_tree_p (xoffset
))
2738 poly_offset_int woffset
2739 = (wi::to_poly_offset (xoffset
)
2740 + (wi::to_offset (DECL_FIELD_BIT_OFFSET (field
))
2741 >> LOG2_BITS_PER_UNIT
)
2743 if (!woffset
.to_shwi (offset
))
2749 x
= TREE_OPERAND (x
, 0);
2751 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
2754 /* Return nonzero if we can determine the exprs corresponding to memrefs
2755 X and Y and they do not overlap.
2756 If LOOP_VARIANT is set, skip offset-based disambiguation */
2759 nonoverlapping_memrefs_p (const_rtx x
, const_rtx y
, bool loop_invariant
)
2761 tree exprx
= MEM_EXPR (x
), expry
= MEM_EXPR (y
);
2764 bool moffsetx_known_p
, moffsety_known_p
;
2765 poly_int64 moffsetx
= 0, moffsety
= 0;
2766 poly_int64 offsetx
= 0, offsety
= 0, sizex
, sizey
;
2768 /* Unless both have exprs, we can't tell anything. */
2769 if (exprx
== 0 || expry
== 0)
2772 /* For spill-slot accesses make sure we have valid offsets. */
2773 if ((exprx
== get_spill_slot_decl (false)
2774 && ! MEM_OFFSET_KNOWN_P (x
))
2775 || (expry
== get_spill_slot_decl (false)
2776 && ! MEM_OFFSET_KNOWN_P (y
)))
2779 /* If the field reference test failed, look at the DECLs involved. */
2780 moffsetx_known_p
= MEM_OFFSET_KNOWN_P (x
);
2781 if (moffsetx_known_p
)
2782 moffsetx
= MEM_OFFSET (x
);
2783 if (TREE_CODE (exprx
) == COMPONENT_REF
)
2785 tree t
= decl_for_component_ref (exprx
);
2788 adjust_offset_for_component_ref (exprx
, &moffsetx_known_p
, &moffsetx
);
2792 moffsety_known_p
= MEM_OFFSET_KNOWN_P (y
);
2793 if (moffsety_known_p
)
2794 moffsety
= MEM_OFFSET (y
);
2795 if (TREE_CODE (expry
) == COMPONENT_REF
)
2797 tree t
= decl_for_component_ref (expry
);
2800 adjust_offset_for_component_ref (expry
, &moffsety_known_p
, &moffsety
);
2804 if (! DECL_P (exprx
) || ! DECL_P (expry
))
2807 /* If we refer to different gimple registers, or one gimple register
2808 and one non-gimple-register, we know they can't overlap. First,
2809 gimple registers don't have their addresses taken. Now, there
2810 could be more than one stack slot for (different versions of) the
2811 same gimple register, but we can presumably tell they don't
2812 overlap based on offsets from stack base addresses elsewhere.
2813 It's important that we don't proceed to DECL_RTL, because gimple
2814 registers may not pass DECL_RTL_SET_P, and make_decl_rtl won't be
2815 able to do anything about them since no SSA information will have
2816 remained to guide it. */
2817 if (is_gimple_reg (exprx
) || is_gimple_reg (expry
))
2818 return exprx
!= expry
2819 || (moffsetx_known_p
&& moffsety_known_p
2820 && MEM_SIZE_KNOWN_P (x
) && MEM_SIZE_KNOWN_P (y
)
2821 && !offset_overlap_p (moffsety
- moffsetx
,
2822 MEM_SIZE (x
), MEM_SIZE (y
)));
2824 /* With invalid code we can end up storing into the constant pool.
2825 Bail out to avoid ICEing when creating RTL for this.
2826 See gfortran.dg/lto/20091028-2_0.f90. */
2827 if (TREE_CODE (exprx
) == CONST_DECL
2828 || TREE_CODE (expry
) == CONST_DECL
)
2831 /* If one decl is known to be a function or label in a function and
2832 the other is some kind of data, they can't overlap. */
2833 if ((TREE_CODE (exprx
) == FUNCTION_DECL
2834 || TREE_CODE (exprx
) == LABEL_DECL
)
2835 != (TREE_CODE (expry
) == FUNCTION_DECL
2836 || TREE_CODE (expry
) == LABEL_DECL
))
2839 /* If either of the decls doesn't have DECL_RTL set (e.g. marked as
2840 living in multiple places), we can't tell anything. Exception
2841 are FUNCTION_DECLs for which we can create DECL_RTL on demand. */
2842 if ((!DECL_RTL_SET_P (exprx
) && TREE_CODE (exprx
) != FUNCTION_DECL
)
2843 || (!DECL_RTL_SET_P (expry
) && TREE_CODE (expry
) != FUNCTION_DECL
))
2846 rtlx
= DECL_RTL (exprx
);
2847 rtly
= DECL_RTL (expry
);
2849 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
2850 can't overlap unless they are the same because we never reuse that part
2851 of the stack frame used for locals for spilled pseudos. */
2852 if ((!MEM_P (rtlx
) || !MEM_P (rtly
))
2853 && ! rtx_equal_p (rtlx
, rtly
))
2856 /* If we have MEMs referring to different address spaces (which can
2857 potentially overlap), we cannot easily tell from the addresses
2858 whether the references overlap. */
2859 if (MEM_P (rtlx
) && MEM_P (rtly
)
2860 && MEM_ADDR_SPACE (rtlx
) != MEM_ADDR_SPACE (rtly
))
2863 /* Get the base and offsets of both decls. If either is a register, we
2864 know both are and are the same, so use that as the base. The only
2865 we can avoid overlap is if we can deduce that they are nonoverlapping
2866 pieces of that decl, which is very rare. */
2867 basex
= MEM_P (rtlx
) ? XEXP (rtlx
, 0) : rtlx
;
2868 basex
= strip_offset_and_add (basex
, &offsetx
);
2870 basey
= MEM_P (rtly
) ? XEXP (rtly
, 0) : rtly
;
2871 basey
= strip_offset_and_add (basey
, &offsety
);
2873 /* If the bases are different, we know they do not overlap if both
2874 are constants or if one is a constant and the other a pointer into the
2875 stack frame. Otherwise a different base means we can't tell if they
2877 if (compare_base_decls (exprx
, expry
) == 0)
2878 return ((CONSTANT_P (basex
) && CONSTANT_P (basey
))
2879 || (CONSTANT_P (basex
) && REG_P (basey
)
2880 && REGNO_PTR_FRAME_P (REGNO (basey
)))
2881 || (CONSTANT_P (basey
) && REG_P (basex
)
2882 && REGNO_PTR_FRAME_P (REGNO (basex
))));
2884 /* Offset based disambiguation not appropriate for loop invariant */
2888 /* Offset based disambiguation is OK even if we do not know that the
2889 declarations are necessarily different
2890 (i.e. compare_base_decls (exprx, expry) == -1) */
2892 sizex
= (!MEM_P (rtlx
) ? poly_int64 (GET_MODE_SIZE (GET_MODE (rtlx
)))
2893 : MEM_SIZE_KNOWN_P (rtlx
) ? MEM_SIZE (rtlx
)
2895 sizey
= (!MEM_P (rtly
) ? poly_int64 (GET_MODE_SIZE (GET_MODE (rtly
)))
2896 : MEM_SIZE_KNOWN_P (rtly
) ? MEM_SIZE (rtly
)
2899 /* If we have an offset for either memref, it can update the values computed
2901 if (moffsetx_known_p
)
2902 offsetx
+= moffsetx
, sizex
-= moffsetx
;
2903 if (moffsety_known_p
)
2904 offsety
+= moffsety
, sizey
-= moffsety
;
2906 /* If a memref has both a size and an offset, we can use the smaller size.
2907 We can't do this if the offset isn't known because we must view this
2908 memref as being anywhere inside the DECL's MEM. */
2909 if (MEM_SIZE_KNOWN_P (x
) && moffsetx_known_p
)
2910 sizex
= MEM_SIZE (x
);
2911 if (MEM_SIZE_KNOWN_P (y
) && moffsety_known_p
)
2912 sizey
= MEM_SIZE (y
);
2914 return !ranges_maybe_overlap_p (offsetx
, sizex
, offsety
, sizey
);
2917 /* Helper for true_dependence and canon_true_dependence.
2918 Checks for true dependence: X is read after store in MEM takes place.
2920 If MEM_CANONICALIZED is FALSE, then X_ADDR and MEM_ADDR should be
2921 NULL_RTX, and the canonical addresses of MEM and X are both computed
2922 here. If MEM_CANONICALIZED, then MEM must be already canonicalized.
2924 If X_ADDR is non-NULL, it is used in preference of XEXP (x, 0).
2926 Returns 1 if there is a true dependence, 0 otherwise. */
2929 true_dependence_1 (const_rtx mem
, machine_mode mem_mode
, rtx mem_addr
,
2930 const_rtx x
, rtx x_addr
, bool mem_canonicalized
)
2936 gcc_checking_assert (mem_canonicalized
? (mem_addr
!= NULL_RTX
)
2937 : (mem_addr
== NULL_RTX
&& x_addr
== NULL_RTX
));
2939 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2942 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2943 This is used in epilogue deallocation functions, and in cselib. */
2944 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2946 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2948 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
2949 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
2953 x_addr
= XEXP (x
, 0);
2954 x_addr
= get_addr (x_addr
);
2958 mem_addr
= XEXP (mem
, 0);
2959 if (mem_mode
== VOIDmode
)
2960 mem_mode
= GET_MODE (mem
);
2962 true_mem_addr
= get_addr (mem_addr
);
2964 /* Read-only memory is by definition never modified, and therefore can't
2965 conflict with anything. However, don't assume anything when AND
2966 addresses are involved and leave to the code below to determine
2967 dependence. We don't expect to find read-only set on MEM, but
2968 stupid user tricks can produce them, so don't die. */
2969 if (MEM_READONLY_P (x
)
2970 && GET_CODE (x_addr
) != AND
2971 && GET_CODE (true_mem_addr
) != AND
)
2974 /* If we have MEMs referring to different address spaces (which can
2975 potentially overlap), we cannot easily tell from the addresses
2976 whether the references overlap. */
2977 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
2980 base
= find_base_term (x_addr
);
2981 if (base
&& (GET_CODE (base
) == LABEL_REF
2982 || (GET_CODE (base
) == SYMBOL_REF
2983 && CONSTANT_POOL_ADDRESS_P (base
))))
2986 rtx mem_base
= find_base_term (true_mem_addr
);
2987 if (! base_alias_check (x_addr
, base
, true_mem_addr
, mem_base
,
2988 GET_MODE (x
), mem_mode
))
2991 x_addr
= canon_rtx (x_addr
);
2992 if (!mem_canonicalized
)
2993 mem_addr
= canon_rtx (true_mem_addr
);
2995 if ((ret
= memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
2996 SIZE_FOR_MODE (x
), x_addr
, 0)) != -1)
2999 if (mems_in_disjoint_alias_sets_p (x
, mem
))
3002 if (nonoverlapping_memrefs_p (mem
, x
, false))
3005 return rtx_refs_may_alias_p (x
, mem
, true);
3008 /* True dependence: X is read after store in MEM takes place. */
3011 true_dependence (const_rtx mem
, machine_mode mem_mode
, const_rtx x
)
3013 return true_dependence_1 (mem
, mem_mode
, NULL_RTX
,
3014 x
, NULL_RTX
, /*mem_canonicalized=*/false);
3017 /* Canonical true dependence: X is read after store in MEM takes place.
3018 Variant of true_dependence which assumes MEM has already been
3019 canonicalized (hence we no longer do that here).
3020 The mem_addr argument has been added, since true_dependence_1 computed
3021 this value prior to canonicalizing. */
3024 canon_true_dependence (const_rtx mem
, machine_mode mem_mode
, rtx mem_addr
,
3025 const_rtx x
, rtx x_addr
)
3027 return true_dependence_1 (mem
, mem_mode
, mem_addr
,
3028 x
, x_addr
, /*mem_canonicalized=*/true);
3031 /* Returns nonzero if a write to X might alias a previous read from
3032 (or, if WRITEP is true, a write to) MEM.
3033 If X_CANONCALIZED is true, then X_ADDR is the canonicalized address of X,
3034 and X_MODE the mode for that access.
3035 If MEM_CANONICALIZED is true, MEM is canonicalized. */
3038 write_dependence_p (const_rtx mem
,
3039 const_rtx x
, machine_mode x_mode
, rtx x_addr
,
3040 bool mem_canonicalized
, bool x_canonicalized
, bool writep
)
3043 rtx true_mem_addr
, true_x_addr
;
3047 gcc_checking_assert (x_canonicalized
3048 ? (x_addr
!= NULL_RTX
3049 && (x_mode
!= VOIDmode
|| GET_MODE (x
) == VOIDmode
))
3050 : (x_addr
== NULL_RTX
&& x_mode
== VOIDmode
));
3052 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
3055 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
3056 This is used in epilogue deallocation functions. */
3057 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
3059 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
3061 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
3062 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
3066 x_addr
= XEXP (x
, 0);
3067 true_x_addr
= get_addr (x_addr
);
3069 mem_addr
= XEXP (mem
, 0);
3070 true_mem_addr
= get_addr (mem_addr
);
3072 /* A read from read-only memory can't conflict with read-write memory.
3073 Don't assume anything when AND addresses are involved and leave to
3074 the code below to determine dependence. */
3076 && MEM_READONLY_P (mem
)
3077 && GET_CODE (true_x_addr
) != AND
3078 && GET_CODE (true_mem_addr
) != AND
)
3081 /* If we have MEMs referring to different address spaces (which can
3082 potentially overlap), we cannot easily tell from the addresses
3083 whether the references overlap. */
3084 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
3087 base
= find_base_term (true_mem_addr
);
3090 && (GET_CODE (base
) == LABEL_REF
3091 || (GET_CODE (base
) == SYMBOL_REF
3092 && CONSTANT_POOL_ADDRESS_P (base
))))
3095 rtx x_base
= find_base_term (true_x_addr
);
3096 if (! base_alias_check (true_x_addr
, x_base
, true_mem_addr
, base
,
3097 GET_MODE (x
), GET_MODE (mem
)))
3100 if (!x_canonicalized
)
3102 x_addr
= canon_rtx (true_x_addr
);
3103 x_mode
= GET_MODE (x
);
3105 if (!mem_canonicalized
)
3106 mem_addr
= canon_rtx (true_mem_addr
);
3108 if ((ret
= memrefs_conflict_p (SIZE_FOR_MODE (mem
), mem_addr
,
3109 GET_MODE_SIZE (x_mode
), x_addr
, 0)) != -1)
3112 if (nonoverlapping_memrefs_p (x
, mem
, false))
3115 return rtx_refs_may_alias_p (x
, mem
, false);
3118 /* Anti dependence: X is written after read in MEM takes place. */
3121 anti_dependence (const_rtx mem
, const_rtx x
)
3123 return write_dependence_p (mem
, x
, VOIDmode
, NULL_RTX
,
3124 /*mem_canonicalized=*/false,
3125 /*x_canonicalized*/false, /*writep=*/false);
3128 /* Likewise, but we already have a canonicalized MEM, and X_ADDR for X.
3129 Also, consider X in X_MODE (which might be from an enclosing
3130 STRICT_LOW_PART / ZERO_EXTRACT).
3131 If MEM_CANONICALIZED is true, MEM is canonicalized. */
3134 canon_anti_dependence (const_rtx mem
, bool mem_canonicalized
,
3135 const_rtx x
, machine_mode x_mode
, rtx x_addr
)
3137 return write_dependence_p (mem
, x
, x_mode
, x_addr
,
3138 mem_canonicalized
, /*x_canonicalized=*/true,
3142 /* Output dependence: X is written after store in MEM takes place. */
3145 output_dependence (const_rtx mem
, const_rtx x
)
3147 return write_dependence_p (mem
, x
, VOIDmode
, NULL_RTX
,
3148 /*mem_canonicalized=*/false,
3149 /*x_canonicalized*/false, /*writep=*/true);
3152 /* Likewise, but we already have a canonicalized MEM, and X_ADDR for X.
3153 Also, consider X in X_MODE (which might be from an enclosing
3154 STRICT_LOW_PART / ZERO_EXTRACT).
3155 If MEM_CANONICALIZED is true, MEM is canonicalized. */
3158 canon_output_dependence (const_rtx mem
, bool mem_canonicalized
,
3159 const_rtx x
, machine_mode x_mode
, rtx x_addr
)
3161 return write_dependence_p (mem
, x
, x_mode
, x_addr
,
3162 mem_canonicalized
, /*x_canonicalized=*/true,
3168 /* Check whether X may be aliased with MEM. Don't do offset-based
3169 memory disambiguation & TBAA. */
3171 may_alias_p (const_rtx mem
, const_rtx x
)
3173 rtx x_addr
, mem_addr
;
3175 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
3178 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
3179 This is used in epilogue deallocation functions. */
3180 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
3182 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
3184 if (MEM_ALIAS_SET (x
) == ALIAS_SET_MEMORY_BARRIER
3185 || MEM_ALIAS_SET (mem
) == ALIAS_SET_MEMORY_BARRIER
)
3188 x_addr
= XEXP (x
, 0);
3189 x_addr
= get_addr (x_addr
);
3191 mem_addr
= XEXP (mem
, 0);
3192 mem_addr
= get_addr (mem_addr
);
3194 /* Read-only memory is by definition never modified, and therefore can't
3195 conflict with anything. However, don't assume anything when AND
3196 addresses are involved and leave to the code below to determine
3197 dependence. We don't expect to find read-only set on MEM, but
3198 stupid user tricks can produce them, so don't die. */
3199 if (MEM_READONLY_P (x
)
3200 && GET_CODE (x_addr
) != AND
3201 && GET_CODE (mem_addr
) != AND
)
3204 /* If we have MEMs referring to different address spaces (which can
3205 potentially overlap), we cannot easily tell from the addresses
3206 whether the references overlap. */
3207 if (MEM_ADDR_SPACE (mem
) != MEM_ADDR_SPACE (x
))
3210 rtx x_base
= find_base_term (x_addr
);
3211 rtx mem_base
= find_base_term (mem_addr
);
3212 if (! base_alias_check (x_addr
, x_base
, mem_addr
, mem_base
,
3213 GET_MODE (x
), GET_MODE (mem_addr
)))
3216 if (nonoverlapping_memrefs_p (mem
, x
, true))
3219 /* TBAA not valid for loop_invarint */
3220 return rtx_refs_may_alias_p (x
, mem
, false);
3224 init_alias_target (void)
3228 if (!arg_base_value
)
3229 arg_base_value
= gen_rtx_ADDRESS (VOIDmode
, 0);
3231 memset (static_reg_base_value
, 0, sizeof static_reg_base_value
);
3233 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3234 /* Check whether this register can hold an incoming pointer
3235 argument. FUNCTION_ARG_REGNO_P tests outgoing register
3236 numbers, so translate if necessary due to register windows. */
3237 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i
))
3238 && targetm
.hard_regno_mode_ok (i
, Pmode
))
3239 static_reg_base_value
[i
] = arg_base_value
;
3241 /* RTL code is required to be consistent about whether it uses the
3242 stack pointer, the frame pointer or the argument pointer to
3243 access a given area of the frame. We can therefore use the
3244 base address to distinguish between the different areas. */
3245 static_reg_base_value
[STACK_POINTER_REGNUM
]
3246 = unique_base_value (UNIQUE_BASE_VALUE_SP
);
3247 static_reg_base_value
[ARG_POINTER_REGNUM
]
3248 = unique_base_value (UNIQUE_BASE_VALUE_ARGP
);
3249 static_reg_base_value
[FRAME_POINTER_REGNUM
]
3250 = unique_base_value (UNIQUE_BASE_VALUE_FP
);
3252 /* The above rules extend post-reload, with eliminations applying
3253 consistently to each of the three pointers. Cope with cases in
3254 which the frame pointer is eliminated to the hard frame pointer
3255 rather than the stack pointer. */
3256 if (!HARD_FRAME_POINTER_IS_FRAME_POINTER
)
3257 static_reg_base_value
[HARD_FRAME_POINTER_REGNUM
]
3258 = unique_base_value (UNIQUE_BASE_VALUE_HFP
);
3261 /* Set MEMORY_MODIFIED when X modifies DATA (that is assumed
3262 to be memory reference. */
3263 static bool memory_modified
;
3265 memory_modified_1 (rtx x
, const_rtx pat ATTRIBUTE_UNUSED
, void *data
)
3269 if (anti_dependence (x
, (const_rtx
)data
) || output_dependence (x
, (const_rtx
)data
))
3270 memory_modified
= true;
3275 /* Return true when INSN possibly modify memory contents of MEM
3276 (i.e. address can be modified). */
3278 memory_modified_in_insn_p (const_rtx mem
, const_rtx insn
)
3282 /* Conservatively assume all non-readonly MEMs might be modified in
3286 memory_modified
= false;
3287 note_stores (PATTERN (insn
), memory_modified_1
, CONST_CAST_RTX(mem
));
3288 return memory_modified
;
3291 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
3295 init_alias_analysis (void)
3297 unsigned int maxreg
= max_reg_num ();
3306 timevar_push (TV_ALIAS_ANALYSIS
);
3308 vec_safe_grow_cleared (reg_known_value
, maxreg
- FIRST_PSEUDO_REGISTER
);
3309 reg_known_equiv_p
= sbitmap_alloc (maxreg
- FIRST_PSEUDO_REGISTER
);
3310 bitmap_clear (reg_known_equiv_p
);
3312 /* If we have memory allocated from the previous run, use it. */
3313 if (old_reg_base_value
)
3314 reg_base_value
= old_reg_base_value
;
3317 reg_base_value
->truncate (0);
3319 vec_safe_grow_cleared (reg_base_value
, maxreg
);
3321 new_reg_base_value
= XNEWVEC (rtx
, maxreg
);
3322 reg_seen
= sbitmap_alloc (maxreg
);
3324 /* The basic idea is that each pass through this loop will use the
3325 "constant" information from the previous pass to propagate alias
3326 information through another level of assignments.
3328 The propagation is done on the CFG in reverse post-order, to propagate
3329 things forward as far as possible in each iteration.
3331 This could get expensive if the assignment chains are long. Maybe
3332 we should throttle the number of iterations, possibly based on
3333 the optimization level or flag_expensive_optimizations.
3335 We could propagate more information in the first pass by making use
3336 of DF_REG_DEF_COUNT to determine immediately that the alias information
3337 for a pseudo is "constant".
3339 A program with an uninitialized variable can cause an infinite loop
3340 here. Instead of doing a full dataflow analysis to detect such problems
3341 we just cap the number of iterations for the loop.
3343 The state of the arrays for the set chain in question does not matter
3344 since the program has undefined behavior. */
3346 rpo
= XNEWVEC (int, n_basic_blocks_for_fn (cfun
));
3347 rpo_cnt
= pre_and_rev_post_order_compute (NULL
, rpo
, false);
3349 /* The prologue/epilogue insns are not threaded onto the
3350 insn chain until after reload has completed. Thus,
3351 there is no sense wasting time checking if INSN is in
3352 the prologue/epilogue until after reload has completed. */
3353 bool could_be_prologue_epilogue
= ((targetm
.have_prologue ()
3354 || targetm
.have_epilogue ())
3355 && reload_completed
);
3360 /* Assume nothing will change this iteration of the loop. */
3363 /* We want to assign the same IDs each iteration of this loop, so
3364 start counting from one each iteration of the loop. */
3367 /* We're at the start of the function each iteration through the
3368 loop, so we're copying arguments. */
3369 copying_arguments
= true;
3371 /* Wipe the potential alias information clean for this pass. */
3372 memset (new_reg_base_value
, 0, maxreg
* sizeof (rtx
));
3374 /* Wipe the reg_seen array clean. */
3375 bitmap_clear (reg_seen
);
3377 /* Initialize the alias information for this pass. */
3378 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3379 if (static_reg_base_value
[i
]
3380 /* Don't treat the hard frame pointer as special if we
3381 eliminated the frame pointer to the stack pointer instead. */
3382 && !(i
== HARD_FRAME_POINTER_REGNUM
3384 && !frame_pointer_needed
3385 && targetm
.can_eliminate (FRAME_POINTER_REGNUM
,
3386 STACK_POINTER_REGNUM
)))
3388 new_reg_base_value
[i
] = static_reg_base_value
[i
];
3389 bitmap_set_bit (reg_seen
, i
);
3392 /* Walk the insns adding values to the new_reg_base_value array. */
3393 for (i
= 0; i
< rpo_cnt
; i
++)
3395 basic_block bb
= BASIC_BLOCK_FOR_FN (cfun
, rpo
[i
]);
3396 FOR_BB_INSNS (bb
, insn
)
3398 if (NONDEBUG_INSN_P (insn
))
3402 if (could_be_prologue_epilogue
3403 && prologue_epilogue_contains (insn
))
3406 /* If this insn has a noalias note, process it, Otherwise,
3407 scan for sets. A simple set will have no side effects
3408 which could change the base value of any other register. */
3410 if (GET_CODE (PATTERN (insn
)) == SET
3411 && REG_NOTES (insn
) != 0
3412 && find_reg_note (insn
, REG_NOALIAS
, NULL_RTX
))
3413 record_set (SET_DEST (PATTERN (insn
)), NULL_RTX
, NULL
);
3415 note_stores (PATTERN (insn
), record_set
, NULL
);
3417 set
= single_set (insn
);
3420 && REG_P (SET_DEST (set
))
3421 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
)
3423 unsigned int regno
= REGNO (SET_DEST (set
));
3424 rtx src
= SET_SRC (set
);
3427 note
= find_reg_equal_equiv_note (insn
);
3428 if (note
&& REG_NOTE_KIND (note
) == REG_EQUAL
3429 && DF_REG_DEF_COUNT (regno
) != 1)
3433 if (note
!= NULL_RTX
3434 && GET_CODE (XEXP (note
, 0)) != EXPR_LIST
3435 && ! rtx_varies_p (XEXP (note
, 0), 1)
3436 && ! reg_overlap_mentioned_p (SET_DEST (set
),
3439 set_reg_known_value (regno
, XEXP (note
, 0));
3440 set_reg_known_equiv_p (regno
,
3441 REG_NOTE_KIND (note
) == REG_EQUIV
);
3443 else if (DF_REG_DEF_COUNT (regno
) == 1
3444 && GET_CODE (src
) == PLUS
3445 && REG_P (XEXP (src
, 0))
3446 && (t
= get_reg_known_value (REGNO (XEXP (src
, 0))))
3447 && poly_int_rtx_p (XEXP (src
, 1), &offset
))
3449 t
= plus_constant (GET_MODE (src
), t
, offset
);
3450 set_reg_known_value (regno
, t
);
3451 set_reg_known_equiv_p (regno
, false);
3453 else if (DF_REG_DEF_COUNT (regno
) == 1
3454 && ! rtx_varies_p (src
, 1))
3456 set_reg_known_value (regno
, src
);
3457 set_reg_known_equiv_p (regno
, false);
3461 else if (NOTE_P (insn
)
3462 && NOTE_KIND (insn
) == NOTE_INSN_FUNCTION_BEG
)
3463 copying_arguments
= false;
3467 /* Now propagate values from new_reg_base_value to reg_base_value. */
3468 gcc_assert (maxreg
== (unsigned int) max_reg_num ());
3470 for (ui
= 0; ui
< maxreg
; ui
++)
3472 if (new_reg_base_value
[ui
]
3473 && new_reg_base_value
[ui
] != (*reg_base_value
)[ui
]
3474 && ! rtx_equal_p (new_reg_base_value
[ui
], (*reg_base_value
)[ui
]))
3476 (*reg_base_value
)[ui
] = new_reg_base_value
[ui
];
3481 while (changed
&& ++pass
< MAX_ALIAS_LOOP_PASSES
);
3484 /* Fill in the remaining entries. */
3485 FOR_EACH_VEC_ELT (*reg_known_value
, i
, val
)
3487 int regno
= i
+ FIRST_PSEUDO_REGISTER
;
3489 set_reg_known_value (regno
, regno_reg_rtx
[regno
]);
3493 free (new_reg_base_value
);
3494 new_reg_base_value
= 0;
3495 sbitmap_free (reg_seen
);
3497 timevar_pop (TV_ALIAS_ANALYSIS
);
3500 /* Equate REG_BASE_VALUE (reg1) to REG_BASE_VALUE (reg2).
3501 Special API for var-tracking pass purposes. */
3504 vt_equate_reg_base_value (const_rtx reg1
, const_rtx reg2
)
3506 (*reg_base_value
)[REGNO (reg1
)] = REG_BASE_VALUE (reg2
);
3510 end_alias_analysis (void)
3512 old_reg_base_value
= reg_base_value
;
3513 vec_free (reg_known_value
);
3514 sbitmap_free (reg_known_equiv_p
);
3518 dump_alias_stats_in_alias_c (FILE *s
)
3520 fprintf (s
, " TBAA oracle: %llu disambiguations %llu queries\n"
3521 " %llu are in alias set 0\n"
3522 " %llu queries asked about the same object\n"
3523 " %llu queries asked about the same alias set\n"
3524 " %llu access volatile\n"
3525 " %llu are dependent in the DAG\n"
3526 " %llu are aritificially in conflict with void *\n",
3527 alias_stats
.num_disambiguated
,
3528 alias_stats
.num_alias_zero
+ alias_stats
.num_same_alias_set
3529 + alias_stats
.num_same_objects
+ alias_stats
.num_volatile
3530 + alias_stats
.num_dag
+ alias_stats
.num_disambiguated
3531 + alias_stats
.num_universal
,
3532 alias_stats
.num_alias_zero
, alias_stats
.num_same_alias_set
,
3533 alias_stats
.num_same_objects
, alias_stats
.num_volatile
,
3534 alias_stats
.num_dag
, alias_stats
.num_universal
);
3536 #include "gt-alias.h"