1 /* Alias analysis for GNU C
2 Copyright (C) 1997, 1998, 1999, 2000, 2001 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 2, 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 COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
30 #include "hard-reg-set.h"
31 #include "basic-block.h"
36 #include "splay-tree.h"
38 #include "langhooks.h"
41 /* The alias sets assigned to MEMs assist the back-end in determining
42 which MEMs can alias which other MEMs. In general, two MEMs in
43 different alias sets cannot alias each other, with one important
44 exception. Consider something like:
46 struct S {int i; double d; };
48 a store to an `S' can alias something of either type `int' or type
49 `double'. (However, a store to an `int' cannot alias a `double'
50 and vice versa.) We indicate this via a tree structure that looks
58 (The arrows are directed and point downwards.)
59 In this situation we say the alias set for `struct S' is the
60 `superset' and that those for `int' and `double' are `subsets'.
62 To see whether two alias sets can point to the same memory, we must
63 see if either alias set is a subset of the other. We need not trace
64 past immediate descendents, however, since we propagate all
65 grandchildren up one level.
67 Alias set zero is implicitly a superset of all other alias sets.
68 However, this is no actual entry for alias set zero. It is an
69 error to attempt to explicitly construct a subset of zero. */
71 typedef struct alias_set_entry
73 /* The alias set number, as stored in MEM_ALIAS_SET. */
74 HOST_WIDE_INT alias_set
;
76 /* The children of the alias set. These are not just the immediate
77 children, but, in fact, all descendents. So, if we have:
79 struct T { struct S s; float f; }
81 continuing our example above, the children here will be all of
82 `int', `double', `float', and `struct S'. */
85 /* Nonzero if would have a child of zero: this effectively makes this
86 alias set the same as alias set zero. */
90 static int rtx_equal_for_memref_p
PARAMS ((rtx
, rtx
));
91 static rtx find_symbolic_term
PARAMS ((rtx
));
92 rtx get_addr
PARAMS ((rtx
));
93 static int memrefs_conflict_p
PARAMS ((int, rtx
, int, rtx
,
95 static void record_set
PARAMS ((rtx
, rtx
, void *));
96 static rtx find_base_term
PARAMS ((rtx
));
97 static int base_alias_check
PARAMS ((rtx
, rtx
, enum machine_mode
,
99 static rtx find_base_value
PARAMS ((rtx
));
100 static int mems_in_disjoint_alias_sets_p
PARAMS ((rtx
, rtx
));
101 static int insert_subset_children
PARAMS ((splay_tree_node
, void*));
102 static tree find_base_decl
PARAMS ((tree
));
103 static alias_set_entry get_alias_set_entry
PARAMS ((HOST_WIDE_INT
));
104 static rtx fixed_scalar_and_varying_struct_p
PARAMS ((rtx
, rtx
, rtx
, rtx
,
105 int (*) (rtx
, int)));
106 static int aliases_everything_p
PARAMS ((rtx
));
107 static bool nonoverlapping_component_refs_p
PARAMS ((tree
, tree
));
108 static tree decl_for_component_ref
PARAMS ((tree
));
109 static rtx adjust_offset_for_component_ref
PARAMS ((tree
, rtx
));
110 static int nonoverlapping_memrefs_p
PARAMS ((rtx
, rtx
));
111 static int write_dependence_p
PARAMS ((rtx
, rtx
, int));
113 static int nonlocal_mentioned_p_1
PARAMS ((rtx
*, void *));
114 static int nonlocal_mentioned_p
PARAMS ((rtx
));
115 static int nonlocal_referenced_p_1
PARAMS ((rtx
*, void *));
116 static int nonlocal_referenced_p
PARAMS ((rtx
));
117 static int nonlocal_set_p_1
PARAMS ((rtx
*, void *));
118 static int nonlocal_set_p
PARAMS ((rtx
));
120 /* Set up all info needed to perform alias analysis on memory references. */
122 /* Returns the size in bytes of the mode of X. */
123 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
125 /* Returns nonzero if MEM1 and MEM2 do not alias because they are in
126 different alias sets. We ignore alias sets in functions making use
127 of variable arguments because the va_arg macros on some systems are
129 #define DIFFERENT_ALIAS_SETS_P(MEM1, MEM2) \
130 mems_in_disjoint_alias_sets_p (MEM1, MEM2)
132 /* Cap the number of passes we make over the insns propagating alias
133 information through set chains. 10 is a completely arbitrary choice. */
134 #define MAX_ALIAS_LOOP_PASSES 10
136 /* reg_base_value[N] gives an address to which register N is related.
137 If all sets after the first add or subtract to the current value
138 or otherwise modify it so it does not point to a different top level
139 object, reg_base_value[N] is equal to the address part of the source
142 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
143 expressions represent certain special values: function arguments and
144 the stack, frame, and argument pointers.
146 The contents of an ADDRESS is not normally used, the mode of the
147 ADDRESS determines whether the ADDRESS is a function argument or some
148 other special value. Pointer equality, not rtx_equal_p, determines whether
149 two ADDRESS expressions refer to the same base address.
151 The only use of the contents of an ADDRESS is for determining if the
152 current function performs nonlocal memory memory references for the
153 purposes of marking the function as a constant function. */
155 static GTY((length ("reg_base_value_size"))) rtx
*reg_base_value
;
156 static rtx
*new_reg_base_value
;
157 static unsigned int reg_base_value_size
; /* size of reg_base_value array */
159 #define REG_BASE_VALUE(X) \
160 (REGNO (X) < reg_base_value_size \
161 ? reg_base_value[REGNO (X)] : 0)
163 /* Vector of known invariant relationships between registers. Set in
164 loop unrolling. Indexed by register number, if nonzero the value
165 is an expression describing this register in terms of another.
167 The length of this array is REG_BASE_VALUE_SIZE.
169 Because this array contains only pseudo registers it has no effect
171 static rtx
*alias_invariant
;
173 /* Vector indexed by N giving the initial (unchanging) value known for
174 pseudo-register N. This array is initialized in
175 init_alias_analysis, and does not change until end_alias_analysis
177 rtx
*reg_known_value
;
179 /* Indicates number of valid entries in reg_known_value. */
180 static unsigned int reg_known_value_size
;
182 /* Vector recording for each reg_known_value whether it is due to a
183 REG_EQUIV note. Future passes (viz., reload) may replace the
184 pseudo with the equivalent expression and so we account for the
185 dependences that would be introduced if that happens.
187 The REG_EQUIV notes created in assign_parms may mention the arg
188 pointer, and there are explicit insns in the RTL that modify the
189 arg pointer. Thus we must ensure that such insns don't get
190 scheduled across each other because that would invalidate the
191 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
192 wrong, but solving the problem in the scheduler will likely give
193 better code, so we do it here. */
194 char *reg_known_equiv_p
;
196 /* True when scanning insns from the start of the rtl to the
197 NOTE_INSN_FUNCTION_BEG note. */
198 static int copying_arguments
;
200 /* The splay-tree used to store the various alias set entries. */
201 static splay_tree alias_sets
;
203 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
204 such an entry, or NULL otherwise. */
206 static alias_set_entry
207 get_alias_set_entry (alias_set
)
208 HOST_WIDE_INT alias_set
;
211 = splay_tree_lookup (alias_sets
, (splay_tree_key
) alias_set
);
213 return sn
!= 0 ? ((alias_set_entry
) sn
->value
) : 0;
216 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
217 the two MEMs cannot alias each other. */
220 mems_in_disjoint_alias_sets_p (mem1
, mem2
)
224 #ifdef ENABLE_CHECKING
225 /* Perform a basic sanity check. Namely, that there are no alias sets
226 if we're not using strict aliasing. This helps to catch bugs
227 whereby someone uses PUT_CODE, but doesn't clear MEM_ALIAS_SET, or
228 where a MEM is allocated in some way other than by the use of
229 gen_rtx_MEM, and the MEM_ALIAS_SET is not cleared. If we begin to
230 use alias sets to indicate that spilled registers cannot alias each
231 other, we might need to remove this check. */
232 if (! flag_strict_aliasing
233 && (MEM_ALIAS_SET (mem1
) != 0 || MEM_ALIAS_SET (mem2
) != 0))
237 return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1
), MEM_ALIAS_SET (mem2
));
240 /* Insert the NODE into the splay tree given by DATA. Used by
241 record_alias_subset via splay_tree_foreach. */
244 insert_subset_children (node
, data
)
245 splay_tree_node node
;
248 splay_tree_insert ((splay_tree
) data
, node
->key
, node
->value
);
253 /* Return 1 if the two specified alias sets may conflict. */
256 alias_sets_conflict_p (set1
, set2
)
257 HOST_WIDE_INT set1
, set2
;
261 /* If have no alias set information for one of the operands, we have
262 to assume it can alias anything. */
263 if (set1
== 0 || set2
== 0
264 /* If the two alias sets are the same, they may alias. */
268 /* See if the first alias set is a subset of the second. */
269 ase
= get_alias_set_entry (set1
);
271 && (ase
->has_zero_child
272 || splay_tree_lookup (ase
->children
,
273 (splay_tree_key
) set2
)))
276 /* Now do the same, but with the alias sets reversed. */
277 ase
= get_alias_set_entry (set2
);
279 && (ase
->has_zero_child
280 || splay_tree_lookup (ase
->children
,
281 (splay_tree_key
) set1
)))
284 /* The two alias sets are distinct and neither one is the
285 child of the other. Therefore, they cannot alias. */
289 /* Return 1 if TYPE is a RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE and has
290 has any readonly fields. If any of the fields have types that
291 contain readonly fields, return true as well. */
294 readonly_fields_p (type
)
299 if (TREE_CODE (type
) != RECORD_TYPE
&& TREE_CODE (type
) != UNION_TYPE
300 && TREE_CODE (type
) != QUAL_UNION_TYPE
)
303 for (field
= TYPE_FIELDS (type
); field
!= 0; field
= TREE_CHAIN (field
))
304 if (TREE_CODE (field
) == FIELD_DECL
305 && (TREE_READONLY (field
)
306 || readonly_fields_p (TREE_TYPE (field
))))
312 /* Return 1 if any MEM object of type T1 will always conflict (using the
313 dependency routines in this file) with any MEM object of type T2.
314 This is used when allocating temporary storage. If T1 and/or T2 are
315 NULL_TREE, it means we know nothing about the storage. */
318 objects_must_conflict_p (t1
, t2
)
321 /* If neither has a type specified, we don't know if they'll conflict
322 because we may be using them to store objects of various types, for
323 example the argument and local variables areas of inlined functions. */
324 if (t1
== 0 && t2
== 0)
327 /* If one or the other has readonly fields or is readonly,
328 then they may not conflict. */
329 if ((t1
!= 0 && readonly_fields_p (t1
))
330 || (t2
!= 0 && readonly_fields_p (t2
))
331 || (t1
!= 0 && TYPE_READONLY (t1
))
332 || (t2
!= 0 && TYPE_READONLY (t2
)))
335 /* If they are the same type, they must conflict. */
337 /* Likewise if both are volatile. */
338 || (t1
!= 0 && TYPE_VOLATILE (t1
) && t2
!= 0 && TYPE_VOLATILE (t2
)))
341 /* If one is aggregate and the other is scalar then they may not
343 if ((t1
!= 0 && AGGREGATE_TYPE_P (t1
))
344 != (t2
!= 0 && AGGREGATE_TYPE_P (t2
)))
347 /* Otherwise they conflict only if the alias sets conflict. */
348 return alias_sets_conflict_p (t1
? get_alias_set (t1
) : 0,
349 t2
? get_alias_set (t2
) : 0);
352 /* T is an expression with pointer type. Find the DECL on which this
353 expression is based. (For example, in `a[i]' this would be `a'.)
354 If there is no such DECL, or a unique decl cannot be determined,
355 NULL_TREE is returned. */
363 if (t
== 0 || t
== error_mark_node
|| ! POINTER_TYPE_P (TREE_TYPE (t
)))
366 /* If this is a declaration, return it. */
367 if (TREE_CODE_CLASS (TREE_CODE (t
)) == 'd')
370 /* Handle general expressions. It would be nice to deal with
371 COMPONENT_REFs here. If we could tell that `a' and `b' were the
372 same, then `a->f' and `b->f' are also the same. */
373 switch (TREE_CODE_CLASS (TREE_CODE (t
)))
376 return find_base_decl (TREE_OPERAND (t
, 0));
379 /* Return 0 if found in neither or both are the same. */
380 d0
= find_base_decl (TREE_OPERAND (t
, 0));
381 d1
= find_base_decl (TREE_OPERAND (t
, 1));
392 d0
= find_base_decl (TREE_OPERAND (t
, 0));
393 d1
= find_base_decl (TREE_OPERAND (t
, 1));
394 d2
= find_base_decl (TREE_OPERAND (t
, 2));
396 /* Set any nonzero values from the last, then from the first. */
397 if (d1
== 0) d1
= d2
;
398 if (d0
== 0) d0
= d1
;
399 if (d1
== 0) d1
= d0
;
400 if (d2
== 0) d2
= d1
;
402 /* At this point all are nonzero or all are zero. If all three are the
403 same, return it. Otherwise, return zero. */
404 return (d0
== d1
&& d1
== d2
) ? d0
: 0;
411 /* Return 1 if all the nested component references handled by
412 get_inner_reference in T are such that we can address the object in T. */
418 /* If we're at the end, it is vacuously addressable. */
419 if (! handled_component_p (t
))
422 /* Bitfields are never addressable. */
423 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
426 /* Fields are addressable unless they are marked as nonaddressable or
427 the containing type has alias set 0. */
428 else if (TREE_CODE (t
) == COMPONENT_REF
429 && ! DECL_NONADDRESSABLE_P (TREE_OPERAND (t
, 1))
430 && get_alias_set (TREE_TYPE (TREE_OPERAND (t
, 0))) != 0
431 && can_address_p (TREE_OPERAND (t
, 0)))
434 /* Likewise for arrays. */
435 else if ((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
436 && ! TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t
, 0)))
437 && get_alias_set (TREE_TYPE (TREE_OPERAND (t
, 0))) != 0
438 && can_address_p (TREE_OPERAND (t
, 0)))
444 /* Return the alias set for T, which may be either a type or an
445 expression. Call language-specific routine for help, if needed. */
453 /* If we're not doing any alias analysis, just assume everything
454 aliases everything else. Also return 0 if this or its type is
456 if (! flag_strict_aliasing
|| t
== error_mark_node
458 && (TREE_TYPE (t
) == 0 || TREE_TYPE (t
) == error_mark_node
)))
461 /* We can be passed either an expression or a type. This and the
462 language-specific routine may make mutually-recursive calls to each other
463 to figure out what to do. At each juncture, we see if this is a tree
464 that the language may need to handle specially. First handle things that
469 tree placeholder_ptr
= 0;
471 /* Remove any nops, then give the language a chance to do
472 something with this tree before we look at it. */
474 set
= (*lang_hooks
.get_alias_set
) (t
);
478 /* First see if the actual object referenced is an INDIRECT_REF from a
479 restrict-qualified pointer or a "void *". Replace
480 PLACEHOLDER_EXPRs. */
481 while (TREE_CODE (inner
) == PLACEHOLDER_EXPR
482 || handled_component_p (inner
))
484 if (TREE_CODE (inner
) == PLACEHOLDER_EXPR
)
485 inner
= find_placeholder (inner
, &placeholder_ptr
);
487 inner
= TREE_OPERAND (inner
, 0);
492 /* Check for accesses through restrict-qualified pointers. */
493 if (TREE_CODE (inner
) == INDIRECT_REF
)
495 tree decl
= find_base_decl (TREE_OPERAND (inner
, 0));
497 if (decl
&& DECL_POINTER_ALIAS_SET_KNOWN_P (decl
))
499 /* If we haven't computed the actual alias set, do it now. */
500 if (DECL_POINTER_ALIAS_SET (decl
) == -2)
502 /* No two restricted pointers can point at the same thing.
503 However, a restricted pointer can point at the same thing
504 as an unrestricted pointer, if that unrestricted pointer
505 is based on the restricted pointer. So, we make the
506 alias set for the restricted pointer a subset of the
507 alias set for the type pointed to by the type of the
509 HOST_WIDE_INT pointed_to_alias_set
510 = get_alias_set (TREE_TYPE (TREE_TYPE (decl
)));
512 if (pointed_to_alias_set
== 0)
513 /* It's not legal to make a subset of alias set zero. */
517 DECL_POINTER_ALIAS_SET (decl
) = new_alias_set ();
518 record_alias_subset (pointed_to_alias_set
,
519 DECL_POINTER_ALIAS_SET (decl
));
523 /* We use the alias set indicated in the declaration. */
524 return DECL_POINTER_ALIAS_SET (decl
);
527 /* If we have an INDIRECT_REF via a void pointer, we don't
528 know anything about what that might alias. */
529 else if (TREE_CODE (TREE_TYPE (inner
)) == VOID_TYPE
)
533 /* Otherwise, pick up the outermost object that we could have a pointer
534 to, processing conversion and PLACEHOLDER_EXPR as above. */
536 while (TREE_CODE (t
) == PLACEHOLDER_EXPR
537 || (handled_component_p (t
) && ! can_address_p (t
)))
539 if (TREE_CODE (t
) == PLACEHOLDER_EXPR
)
540 t
= find_placeholder (t
, &placeholder_ptr
);
542 t
= TREE_OPERAND (t
, 0);
547 /* If we've already determined the alias set for a decl, just return
548 it. This is necessary for C++ anonymous unions, whose component
549 variables don't look like union members (boo!). */
550 if (TREE_CODE (t
) == VAR_DECL
551 && DECL_RTL_SET_P (t
) && GET_CODE (DECL_RTL (t
)) == MEM
)
552 return MEM_ALIAS_SET (DECL_RTL (t
));
554 /* Now all we care about is the type. */
558 /* Variant qualifiers don't affect the alias set, so get the main
559 variant. If this is a type with a known alias set, return it. */
560 t
= TYPE_MAIN_VARIANT (t
);
561 if (TYPE_ALIAS_SET_KNOWN_P (t
))
562 return TYPE_ALIAS_SET (t
);
564 /* See if the language has special handling for this type. */
565 set
= (*lang_hooks
.get_alias_set
) (t
);
569 /* There are no objects of FUNCTION_TYPE, so there's no point in
570 using up an alias set for them. (There are, of course, pointers
571 and references to functions, but that's different.) */
572 else if (TREE_CODE (t
) == FUNCTION_TYPE
)
575 /* Otherwise make a new alias set for this type. */
576 set
= new_alias_set ();
578 TYPE_ALIAS_SET (t
) = set
;
580 /* If this is an aggregate type, we must record any component aliasing
582 if (AGGREGATE_TYPE_P (t
) || TREE_CODE (t
) == COMPLEX_TYPE
)
583 record_component_aliases (t
);
588 /* Return a brand-new alias set. */
593 static HOST_WIDE_INT last_alias_set
;
595 if (flag_strict_aliasing
)
596 return ++last_alias_set
;
601 /* Indicate that things in SUBSET can alias things in SUPERSET, but
602 not vice versa. For example, in C, a store to an `int' can alias a
603 structure containing an `int', but not vice versa. Here, the
604 structure would be the SUPERSET and `int' the SUBSET. This
605 function should be called only once per SUPERSET/SUBSET pair.
607 It is illegal for SUPERSET to be zero; everything is implicitly a
608 subset of alias set zero. */
611 record_alias_subset (superset
, subset
)
612 HOST_WIDE_INT superset
;
613 HOST_WIDE_INT subset
;
615 alias_set_entry superset_entry
;
616 alias_set_entry subset_entry
;
618 /* It is possible in complex type situations for both sets to be the same,
619 in which case we can ignore this operation. */
620 if (superset
== subset
)
626 superset_entry
= get_alias_set_entry (superset
);
627 if (superset_entry
== 0)
629 /* Create an entry for the SUPERSET, so that we have a place to
630 attach the SUBSET. */
632 = (alias_set_entry
) xmalloc (sizeof (struct alias_set_entry
));
633 superset_entry
->alias_set
= superset
;
634 superset_entry
->children
635 = splay_tree_new (splay_tree_compare_ints
, 0, 0);
636 superset_entry
->has_zero_child
= 0;
637 splay_tree_insert (alias_sets
, (splay_tree_key
) superset
,
638 (splay_tree_value
) superset_entry
);
642 superset_entry
->has_zero_child
= 1;
645 subset_entry
= get_alias_set_entry (subset
);
646 /* If there is an entry for the subset, enter all of its children
647 (if they are not already present) as children of the SUPERSET. */
650 if (subset_entry
->has_zero_child
)
651 superset_entry
->has_zero_child
= 1;
653 splay_tree_foreach (subset_entry
->children
, insert_subset_children
,
654 superset_entry
->children
);
657 /* Enter the SUBSET itself as a child of the SUPERSET. */
658 splay_tree_insert (superset_entry
->children
,
659 (splay_tree_key
) subset
, 0);
663 /* Record that component types of TYPE, if any, are part of that type for
664 aliasing purposes. For record types, we only record component types
665 for fields that are marked addressable. For array types, we always
666 record the component types, so the front end should not call this
667 function if the individual component aren't addressable. */
670 record_component_aliases (type
)
673 HOST_WIDE_INT superset
= get_alias_set (type
);
679 switch (TREE_CODE (type
))
682 if (! TYPE_NONALIASED_COMPONENT (type
))
683 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
688 case QUAL_UNION_TYPE
:
689 /* Recursively record aliases for the base classes, if there are any */
690 if (TYPE_BINFO (type
) != NULL
&& TYPE_BINFO_BASETYPES (type
) != NULL
)
693 for (i
= 0; i
< TREE_VEC_LENGTH (TYPE_BINFO_BASETYPES (type
)); i
++)
695 tree binfo
= TREE_VEC_ELT (TYPE_BINFO_BASETYPES (type
), i
);
696 record_alias_subset (superset
,
697 get_alias_set (BINFO_TYPE (binfo
)));
700 for (field
= TYPE_FIELDS (type
); field
!= 0; field
= TREE_CHAIN (field
))
701 if (TREE_CODE (field
) == FIELD_DECL
&& ! DECL_NONADDRESSABLE_P (field
))
702 record_alias_subset (superset
, get_alias_set (TREE_TYPE (field
)));
706 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
714 /* Allocate an alias set for use in storing and reading from the varargs
718 get_varargs_alias_set ()
720 static HOST_WIDE_INT set
= -1;
723 set
= new_alias_set ();
728 /* Likewise, but used for the fixed portions of the frame, e.g., register
732 get_frame_alias_set ()
734 static HOST_WIDE_INT set
= -1;
737 set
= new_alias_set ();
742 /* Inside SRC, the source of a SET, find a base address. */
745 find_base_value (src
)
750 switch (GET_CODE (src
))
758 /* At the start of a function, argument registers have known base
759 values which may be lost later. Returning an ADDRESS
760 expression here allows optimization based on argument values
761 even when the argument registers are used for other purposes. */
762 if (regno
< FIRST_PSEUDO_REGISTER
&& copying_arguments
)
763 return new_reg_base_value
[regno
];
765 /* If a pseudo has a known base value, return it. Do not do this
766 for non-fixed hard regs since it can result in a circular
767 dependency chain for registers which have values at function entry.
769 The test above is not sufficient because the scheduler may move
770 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
771 if ((regno
>= FIRST_PSEUDO_REGISTER
|| fixed_regs
[regno
])
772 && regno
< reg_base_value_size
773 && reg_base_value
[regno
])
774 return reg_base_value
[regno
];
779 /* Check for an argument passed in memory. Only record in the
780 copying-arguments block; it is too hard to track changes
782 if (copying_arguments
783 && (XEXP (src
, 0) == arg_pointer_rtx
784 || (GET_CODE (XEXP (src
, 0)) == PLUS
785 && XEXP (XEXP (src
, 0), 0) == arg_pointer_rtx
)))
786 return gen_rtx_ADDRESS (VOIDmode
, src
);
791 if (GET_CODE (src
) != PLUS
&& GET_CODE (src
) != MINUS
)
794 /* ... fall through ... */
799 rtx temp
, src_0
= XEXP (src
, 0), src_1
= XEXP (src
, 1);
801 /* If either operand is a REG that is a known pointer, then it
803 if (REG_P (src_0
) && REG_POINTER (src_0
))
804 return find_base_value (src_0
);
805 if (REG_P (src_1
) && REG_POINTER (src_1
))
806 return find_base_value (src_1
);
808 /* If either operand is a REG, then see if we already have
809 a known value for it. */
812 temp
= find_base_value (src_0
);
819 temp
= find_base_value (src_1
);
824 /* If either base is named object or a special address
825 (like an argument or stack reference), then use it for the
828 && (GET_CODE (src_0
) == SYMBOL_REF
829 || GET_CODE (src_0
) == LABEL_REF
830 || (GET_CODE (src_0
) == ADDRESS
831 && GET_MODE (src_0
) != VOIDmode
)))
835 && (GET_CODE (src_1
) == SYMBOL_REF
836 || GET_CODE (src_1
) == LABEL_REF
837 || (GET_CODE (src_1
) == ADDRESS
838 && GET_MODE (src_1
) != VOIDmode
)))
841 /* Guess which operand is the base address:
842 If either operand is a symbol, then it is the base. If
843 either operand is a CONST_INT, then the other is the base. */
844 if (GET_CODE (src_1
) == CONST_INT
|| CONSTANT_P (src_0
))
845 return find_base_value (src_0
);
846 else if (GET_CODE (src_0
) == CONST_INT
|| CONSTANT_P (src_1
))
847 return find_base_value (src_1
);
853 /* The standard form is (lo_sum reg sym) so look only at the
855 return find_base_value (XEXP (src
, 1));
858 /* If the second operand is constant set the base
859 address to the first operand. */
860 if (GET_CODE (XEXP (src
, 1)) == CONST_INT
&& INTVAL (XEXP (src
, 1)) != 0)
861 return find_base_value (XEXP (src
, 0));
865 if (GET_MODE_SIZE (GET_MODE (src
)) < GET_MODE_SIZE (Pmode
))
875 return find_base_value (XEXP (src
, 0));
878 case SIGN_EXTEND
: /* used for NT/Alpha pointers */
880 rtx temp
= find_base_value (XEXP (src
, 0));
882 #ifdef POINTERS_EXTEND_UNSIGNED
883 if (temp
!= 0 && CONSTANT_P (temp
) && GET_MODE (temp
) != Pmode
)
884 temp
= convert_memory_address (Pmode
, temp
);
897 /* Called from init_alias_analysis indirectly through note_stores. */
899 /* While scanning insns to find base values, reg_seen[N] is nonzero if
900 register N has been set in this function. */
901 static char *reg_seen
;
903 /* Addresses which are known not to alias anything else are identified
904 by a unique integer. */
905 static int unique_id
;
908 record_set (dest
, set
, data
)
910 void *data ATTRIBUTE_UNUSED
;
915 if (GET_CODE (dest
) != REG
)
918 regno
= REGNO (dest
);
920 if (regno
>= reg_base_value_size
)
925 /* A CLOBBER wipes out any old value but does not prevent a previously
926 unset register from acquiring a base address (i.e. reg_seen is not
928 if (GET_CODE (set
) == CLOBBER
)
930 new_reg_base_value
[regno
] = 0;
939 new_reg_base_value
[regno
] = 0;
943 new_reg_base_value
[regno
] = gen_rtx_ADDRESS (Pmode
,
944 GEN_INT (unique_id
++));
948 /* This is not the first set. If the new value is not related to the
949 old value, forget the base value. Note that the following code is
951 extern int x, y; int *p = &x; p += (&y-&x);
952 ANSI C does not allow computing the difference of addresses
953 of distinct top level objects. */
954 if (new_reg_base_value
[regno
])
955 switch (GET_CODE (src
))
959 if (XEXP (src
, 0) != dest
&& XEXP (src
, 1) != dest
)
960 new_reg_base_value
[regno
] = 0;
963 /* If the value we add in the PLUS is also a valid base value,
964 this might be the actual base value, and the original value
967 rtx other
= NULL_RTX
;
969 if (XEXP (src
, 0) == dest
)
970 other
= XEXP (src
, 1);
971 else if (XEXP (src
, 1) == dest
)
972 other
= XEXP (src
, 0);
974 if (! other
|| find_base_value (other
))
975 new_reg_base_value
[regno
] = 0;
979 if (XEXP (src
, 0) != dest
|| GET_CODE (XEXP (src
, 1)) != CONST_INT
)
980 new_reg_base_value
[regno
] = 0;
983 new_reg_base_value
[regno
] = 0;
986 /* If this is the first set of a register, record the value. */
987 else if ((regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
988 && ! reg_seen
[regno
] && new_reg_base_value
[regno
] == 0)
989 new_reg_base_value
[regno
] = find_base_value (src
);
994 /* Called from loop optimization when a new pseudo-register is
995 created. It indicates that REGNO is being set to VAL. f INVARIANT
996 is true then this value also describes an invariant relationship
997 which can be used to deduce that two registers with unknown values
1001 record_base_value (regno
, val
, invariant
)
1006 if (regno
>= reg_base_value_size
)
1009 if (invariant
&& alias_invariant
)
1010 alias_invariant
[regno
] = val
;
1012 if (GET_CODE (val
) == REG
)
1014 if (REGNO (val
) < reg_base_value_size
)
1015 reg_base_value
[regno
] = reg_base_value
[REGNO (val
)];
1020 reg_base_value
[regno
] = find_base_value (val
);
1023 /* Clear alias info for a register. This is used if an RTL transformation
1024 changes the value of a register. This is used in flow by AUTO_INC_DEC
1025 optimizations. We don't need to clear reg_base_value, since flow only
1026 changes the offset. */
1029 clear_reg_alias_info (reg
)
1032 unsigned int regno
= REGNO (reg
);
1034 if (regno
< reg_known_value_size
&& regno
>= FIRST_PSEUDO_REGISTER
)
1035 reg_known_value
[regno
] = reg
;
1038 /* Returns a canonical version of X, from the point of view alias
1039 analysis. (For example, if X is a MEM whose address is a register,
1040 and the register has a known value (say a SYMBOL_REF), then a MEM
1041 whose address is the SYMBOL_REF is returned.) */
1047 /* Recursively look for equivalences. */
1048 if (GET_CODE (x
) == REG
&& REGNO (x
) >= FIRST_PSEUDO_REGISTER
1049 && REGNO (x
) < reg_known_value_size
)
1050 return reg_known_value
[REGNO (x
)] == x
1051 ? x
: canon_rtx (reg_known_value
[REGNO (x
)]);
1052 else if (GET_CODE (x
) == PLUS
)
1054 rtx x0
= canon_rtx (XEXP (x
, 0));
1055 rtx x1
= canon_rtx (XEXP (x
, 1));
1057 if (x0
!= XEXP (x
, 0) || x1
!= XEXP (x
, 1))
1059 if (GET_CODE (x0
) == CONST_INT
)
1060 return plus_constant (x1
, INTVAL (x0
));
1061 else if (GET_CODE (x1
) == CONST_INT
)
1062 return plus_constant (x0
, INTVAL (x1
));
1063 return gen_rtx_PLUS (GET_MODE (x
), x0
, x1
);
1067 /* This gives us much better alias analysis when called from
1068 the loop optimizer. Note we want to leave the original
1069 MEM alone, but need to return the canonicalized MEM with
1070 all the flags with their original values. */
1071 else if (GET_CODE (x
) == MEM
)
1072 x
= replace_equiv_address_nv (x
, canon_rtx (XEXP (x
, 0)));
1077 /* Return 1 if X and Y are identical-looking rtx's.
1079 We use the data in reg_known_value above to see if two registers with
1080 different numbers are, in fact, equivalent. */
1083 rtx_equal_for_memref_p (x
, y
)
1091 if (x
== 0 && y
== 0)
1093 if (x
== 0 || y
== 0)
1102 code
= GET_CODE (x
);
1103 /* Rtx's of different codes cannot be equal. */
1104 if (code
!= GET_CODE (y
))
1107 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1108 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1110 if (GET_MODE (x
) != GET_MODE (y
))
1113 /* Some RTL can be compared without a recursive examination. */
1117 return CSELIB_VAL_PTR (x
) == CSELIB_VAL_PTR (y
);
1120 return REGNO (x
) == REGNO (y
);
1123 return XEXP (x
, 0) == XEXP (y
, 0);
1126 return XSTR (x
, 0) == XSTR (y
, 0);
1130 /* There's no need to compare the contents of CONST_DOUBLEs or
1131 CONST_INTs because pointer equality is a good enough
1132 comparison for these nodes. */
1136 return (XINT (x
, 1) == XINT (y
, 1)
1137 && rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0)));
1143 /* For commutative operations, the RTX match if the operand match in any
1144 order. Also handle the simple binary and unary cases without a loop. */
1145 if (code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
1146 return ((rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0))
1147 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 1)))
1148 || (rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 1))
1149 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 0))));
1150 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
1151 return (rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0))
1152 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 1)));
1153 else if (GET_RTX_CLASS (code
) == '1')
1154 return rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0));
1156 /* Compare the elements. If any pair of corresponding elements
1157 fail to match, return 0 for the whole things.
1159 Limit cases to types which actually appear in addresses. */
1161 fmt
= GET_RTX_FORMAT (code
);
1162 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1167 if (XINT (x
, i
) != XINT (y
, i
))
1172 /* Two vectors must have the same length. */
1173 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1176 /* And the corresponding elements must match. */
1177 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1178 if (rtx_equal_for_memref_p (XVECEXP (x
, i
, j
),
1179 XVECEXP (y
, i
, j
)) == 0)
1184 if (rtx_equal_for_memref_p (XEXP (x
, i
), XEXP (y
, i
)) == 0)
1188 /* This can happen for asm operands. */
1190 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1194 /* This can happen for an asm which clobbers memory. */
1198 /* It is believed that rtx's at this level will never
1199 contain anything but integers and other rtx's,
1200 except for within LABEL_REFs and SYMBOL_REFs. */
1208 /* Given an rtx X, find a SYMBOL_REF or LABEL_REF within
1209 X and return it, or return 0 if none found. */
1212 find_symbolic_term (x
)
1219 code
= GET_CODE (x
);
1220 if (code
== SYMBOL_REF
|| code
== LABEL_REF
)
1222 if (GET_RTX_CLASS (code
) == 'o')
1225 fmt
= GET_RTX_FORMAT (code
);
1226 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1232 t
= find_symbolic_term (XEXP (x
, i
));
1236 else if (fmt
[i
] == 'E')
1247 struct elt_loc_list
*l
;
1249 #if defined (FIND_BASE_TERM)
1250 /* Try machine-dependent ways to find the base term. */
1251 x
= FIND_BASE_TERM (x
);
1254 switch (GET_CODE (x
))
1257 return REG_BASE_VALUE (x
);
1260 if (GET_MODE_SIZE (GET_MODE (x
)) < GET_MODE_SIZE (Pmode
))
1270 return find_base_term (XEXP (x
, 0));
1273 case SIGN_EXTEND
: /* Used for Alpha/NT pointers */
1275 rtx temp
= find_base_term (XEXP (x
, 0));
1277 #ifdef POINTERS_EXTEND_UNSIGNED
1278 if (temp
!= 0 && CONSTANT_P (temp
) && GET_MODE (temp
) != Pmode
)
1279 temp
= convert_memory_address (Pmode
, temp
);
1286 val
= CSELIB_VAL_PTR (x
);
1287 for (l
= val
->locs
; l
; l
= l
->next
)
1288 if ((x
= find_base_term (l
->loc
)) != 0)
1294 if (GET_CODE (x
) != PLUS
&& GET_CODE (x
) != MINUS
)
1301 rtx tmp1
= XEXP (x
, 0);
1302 rtx tmp2
= XEXP (x
, 1);
1304 /* This is a little bit tricky since we have to determine which of
1305 the two operands represents the real base address. Otherwise this
1306 routine may return the index register instead of the base register.
1308 That may cause us to believe no aliasing was possible, when in
1309 fact aliasing is possible.
1311 We use a few simple tests to guess the base register. Additional
1312 tests can certainly be added. For example, if one of the operands
1313 is a shift or multiply, then it must be the index register and the
1314 other operand is the base register. */
1316 if (tmp1
== pic_offset_table_rtx
&& CONSTANT_P (tmp2
))
1317 return find_base_term (tmp2
);
1319 /* If either operand is known to be a pointer, then use it
1320 to determine the base term. */
1321 if (REG_P (tmp1
) && REG_POINTER (tmp1
))
1322 return find_base_term (tmp1
);
1324 if (REG_P (tmp2
) && REG_POINTER (tmp2
))
1325 return find_base_term (tmp2
);
1327 /* Neither operand was known to be a pointer. Go ahead and find the
1328 base term for both operands. */
1329 tmp1
= find_base_term (tmp1
);
1330 tmp2
= find_base_term (tmp2
);
1332 /* If either base term is named object or a special address
1333 (like an argument or stack reference), then use it for the
1336 && (GET_CODE (tmp1
) == SYMBOL_REF
1337 || GET_CODE (tmp1
) == LABEL_REF
1338 || (GET_CODE (tmp1
) == ADDRESS
1339 && GET_MODE (tmp1
) != VOIDmode
)))
1343 && (GET_CODE (tmp2
) == SYMBOL_REF
1344 || GET_CODE (tmp2
) == LABEL_REF
1345 || (GET_CODE (tmp2
) == ADDRESS
1346 && GET_MODE (tmp2
) != VOIDmode
)))
1349 /* We could not determine which of the two operands was the
1350 base register and which was the index. So we can determine
1351 nothing from the base alias check. */
1356 if (GET_CODE (XEXP (x
, 1)) == CONST_INT
&& INTVAL (XEXP (x
, 1)) != 0)
1357 return find_base_term (XEXP (x
, 0));
1365 return REG_BASE_VALUE (frame_pointer_rtx
);
1372 /* Return 0 if the addresses X and Y are known to point to different
1373 objects, 1 if they might be pointers to the same object. */
1376 base_alias_check (x
, y
, x_mode
, y_mode
)
1378 enum machine_mode x_mode
, y_mode
;
1380 rtx x_base
= find_base_term (x
);
1381 rtx y_base
= find_base_term (y
);
1383 /* If the address itself has no known base see if a known equivalent
1384 value has one. If either address still has no known base, nothing
1385 is known about aliasing. */
1390 if (! flag_expensive_optimizations
|| (x_c
= canon_rtx (x
)) == x
)
1393 x_base
= find_base_term (x_c
);
1401 if (! flag_expensive_optimizations
|| (y_c
= canon_rtx (y
)) == y
)
1404 y_base
= find_base_term (y_c
);
1409 /* If the base addresses are equal nothing is known about aliasing. */
1410 if (rtx_equal_p (x_base
, y_base
))
1413 /* The base addresses of the read and write are different expressions.
1414 If they are both symbols and they are not accessed via AND, there is
1415 no conflict. We can bring knowledge of object alignment into play
1416 here. For example, on alpha, "char a, b;" can alias one another,
1417 though "char a; long b;" cannot. */
1418 if (GET_CODE (x_base
) != ADDRESS
&& GET_CODE (y_base
) != ADDRESS
)
1420 if (GET_CODE (x
) == AND
&& GET_CODE (y
) == AND
)
1422 if (GET_CODE (x
) == AND
1423 && (GET_CODE (XEXP (x
, 1)) != CONST_INT
1424 || (int) GET_MODE_UNIT_SIZE (y_mode
) < -INTVAL (XEXP (x
, 1))))
1426 if (GET_CODE (y
) == AND
1427 && (GET_CODE (XEXP (y
, 1)) != CONST_INT
1428 || (int) GET_MODE_UNIT_SIZE (x_mode
) < -INTVAL (XEXP (y
, 1))))
1430 /* Differing symbols never alias. */
1434 /* If one address is a stack reference there can be no alias:
1435 stack references using different base registers do not alias,
1436 a stack reference can not alias a parameter, and a stack reference
1437 can not alias a global. */
1438 if ((GET_CODE (x_base
) == ADDRESS
&& GET_MODE (x_base
) == Pmode
)
1439 || (GET_CODE (y_base
) == ADDRESS
&& GET_MODE (y_base
) == Pmode
))
1442 if (! flag_argument_noalias
)
1445 if (flag_argument_noalias
> 1)
1448 /* Weak noalias assertion (arguments are distinct, but may match globals). */
1449 return ! (GET_MODE (x_base
) == VOIDmode
&& GET_MODE (y_base
) == VOIDmode
);
1452 /* Convert the address X into something we can use. This is done by returning
1453 it unchanged unless it is a value; in the latter case we call cselib to get
1454 a more useful rtx. */
1461 struct elt_loc_list
*l
;
1463 if (GET_CODE (x
) != VALUE
)
1465 v
= CSELIB_VAL_PTR (x
);
1466 for (l
= v
->locs
; l
; l
= l
->next
)
1467 if (CONSTANT_P (l
->loc
))
1469 for (l
= v
->locs
; l
; l
= l
->next
)
1470 if (GET_CODE (l
->loc
) != REG
&& GET_CODE (l
->loc
) != MEM
)
1473 return v
->locs
->loc
;
1477 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
1478 where SIZE is the size in bytes of the memory reference. If ADDR
1479 is not modified by the memory reference then ADDR is returned. */
1482 addr_side_effect_eval (addr
, size
, n_refs
)
1489 switch (GET_CODE (addr
))
1492 offset
= (n_refs
+ 1) * size
;
1495 offset
= -(n_refs
+ 1) * size
;
1498 offset
= n_refs
* size
;
1501 offset
= -n_refs
* size
;
1509 addr
= gen_rtx_PLUS (GET_MODE (addr
), XEXP (addr
, 0), GEN_INT (offset
));
1511 addr
= XEXP (addr
, 0);
1516 /* Return nonzero if X and Y (memory addresses) could reference the
1517 same location in memory. C is an offset accumulator. When
1518 C is nonzero, we are testing aliases between X and Y + C.
1519 XSIZE is the size in bytes of the X reference,
1520 similarly YSIZE is the size in bytes for Y.
1522 If XSIZE or YSIZE is zero, we do not know the amount of memory being
1523 referenced (the reference was BLKmode), so make the most pessimistic
1526 If XSIZE or YSIZE is negative, we may access memory outside the object
1527 being referenced as a side effect. This can happen when using AND to
1528 align memory references, as is done on the Alpha.
1530 Nice to notice that varying addresses cannot conflict with fp if no
1531 local variables had their addresses taken, but that's too hard now. */
1534 memrefs_conflict_p (xsize
, x
, ysize
, y
, c
)
1539 if (GET_CODE (x
) == VALUE
)
1541 if (GET_CODE (y
) == VALUE
)
1543 if (GET_CODE (x
) == HIGH
)
1545 else if (GET_CODE (x
) == LO_SUM
)
1548 x
= canon_rtx (addr_side_effect_eval (x
, xsize
, 0));
1549 if (GET_CODE (y
) == HIGH
)
1551 else if (GET_CODE (y
) == LO_SUM
)
1554 y
= canon_rtx (addr_side_effect_eval (y
, ysize
, 0));
1556 if (rtx_equal_for_memref_p (x
, y
))
1558 if (xsize
<= 0 || ysize
<= 0)
1560 if (c
>= 0 && xsize
> c
)
1562 if (c
< 0 && ysize
+c
> 0)
1567 /* This code used to check for conflicts involving stack references and
1568 globals but the base address alias code now handles these cases. */
1570 if (GET_CODE (x
) == PLUS
)
1572 /* The fact that X is canonicalized means that this
1573 PLUS rtx is canonicalized. */
1574 rtx x0
= XEXP (x
, 0);
1575 rtx x1
= XEXP (x
, 1);
1577 if (GET_CODE (y
) == PLUS
)
1579 /* The fact that Y is canonicalized means that this
1580 PLUS rtx is canonicalized. */
1581 rtx y0
= XEXP (y
, 0);
1582 rtx y1
= XEXP (y
, 1);
1584 if (rtx_equal_for_memref_p (x1
, y1
))
1585 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
1586 if (rtx_equal_for_memref_p (x0
, y0
))
1587 return memrefs_conflict_p (xsize
, x1
, ysize
, y1
, c
);
1588 if (GET_CODE (x1
) == CONST_INT
)
1590 if (GET_CODE (y1
) == CONST_INT
)
1591 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
,
1592 c
- INTVAL (x1
) + INTVAL (y1
));
1594 return memrefs_conflict_p (xsize
, x0
, ysize
, y
,
1597 else if (GET_CODE (y1
) == CONST_INT
)
1598 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
1602 else if (GET_CODE (x1
) == CONST_INT
)
1603 return memrefs_conflict_p (xsize
, x0
, ysize
, y
, c
- INTVAL (x1
));
1605 else if (GET_CODE (y
) == PLUS
)
1607 /* The fact that Y is canonicalized means that this
1608 PLUS rtx is canonicalized. */
1609 rtx y0
= XEXP (y
, 0);
1610 rtx y1
= XEXP (y
, 1);
1612 if (GET_CODE (y1
) == CONST_INT
)
1613 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
1618 if (GET_CODE (x
) == GET_CODE (y
))
1619 switch (GET_CODE (x
))
1623 /* Handle cases where we expect the second operands to be the
1624 same, and check only whether the first operand would conflict
1627 rtx x1
= canon_rtx (XEXP (x
, 1));
1628 rtx y1
= canon_rtx (XEXP (y
, 1));
1629 if (! rtx_equal_for_memref_p (x1
, y1
))
1631 x0
= canon_rtx (XEXP (x
, 0));
1632 y0
= canon_rtx (XEXP (y
, 0));
1633 if (rtx_equal_for_memref_p (x0
, y0
))
1634 return (xsize
== 0 || ysize
== 0
1635 || (c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0));
1637 /* Can't properly adjust our sizes. */
1638 if (GET_CODE (x1
) != CONST_INT
)
1640 xsize
/= INTVAL (x1
);
1641 ysize
/= INTVAL (x1
);
1643 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
1647 /* Are these registers known not to be equal? */
1648 if (alias_invariant
)
1650 unsigned int r_x
= REGNO (x
), r_y
= REGNO (y
);
1651 rtx i_x
, i_y
; /* invariant relationships of X and Y */
1653 i_x
= r_x
>= reg_base_value_size
? 0 : alias_invariant
[r_x
];
1654 i_y
= r_y
>= reg_base_value_size
? 0 : alias_invariant
[r_y
];
1656 if (i_x
== 0 && i_y
== 0)
1659 if (! memrefs_conflict_p (xsize
, i_x
? i_x
: x
,
1660 ysize
, i_y
? i_y
: y
, c
))
1669 /* Treat an access through an AND (e.g. a subword access on an Alpha)
1670 as an access with indeterminate size. Assume that references
1671 besides AND are aligned, so if the size of the other reference is
1672 at least as large as the alignment, assume no other overlap. */
1673 if (GET_CODE (x
) == AND
&& GET_CODE (XEXP (x
, 1)) == CONST_INT
)
1675 if (GET_CODE (y
) == AND
|| ysize
< -INTVAL (XEXP (x
, 1)))
1677 return memrefs_conflict_p (xsize
, XEXP (x
, 0), ysize
, y
, c
);
1679 if (GET_CODE (y
) == AND
&& GET_CODE (XEXP (y
, 1)) == CONST_INT
)
1681 /* ??? If we are indexing far enough into the array/structure, we
1682 may yet be able to determine that we can not overlap. But we
1683 also need to that we are far enough from the end not to overlap
1684 a following reference, so we do nothing with that for now. */
1685 if (GET_CODE (x
) == AND
|| xsize
< -INTVAL (XEXP (y
, 1)))
1687 return memrefs_conflict_p (xsize
, x
, ysize
, XEXP (y
, 0), c
);
1690 if (GET_CODE (x
) == ADDRESSOF
)
1692 if (y
== frame_pointer_rtx
1693 || GET_CODE (y
) == ADDRESSOF
)
1694 return xsize
<= 0 || ysize
<= 0;
1696 if (GET_CODE (y
) == ADDRESSOF
)
1698 if (x
== frame_pointer_rtx
)
1699 return xsize
<= 0 || ysize
<= 0;
1704 if (GET_CODE (x
) == CONST_INT
&& GET_CODE (y
) == CONST_INT
)
1706 c
+= (INTVAL (y
) - INTVAL (x
));
1707 return (xsize
<= 0 || ysize
<= 0
1708 || (c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0));
1711 if (GET_CODE (x
) == CONST
)
1713 if (GET_CODE (y
) == CONST
)
1714 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
1715 ysize
, canon_rtx (XEXP (y
, 0)), c
);
1717 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
1720 if (GET_CODE (y
) == CONST
)
1721 return memrefs_conflict_p (xsize
, x
, ysize
,
1722 canon_rtx (XEXP (y
, 0)), c
);
1725 return (xsize
<= 0 || ysize
<= 0
1726 || (rtx_equal_for_memref_p (x
, y
)
1727 && ((c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0))));
1734 /* Functions to compute memory dependencies.
1736 Since we process the insns in execution order, we can build tables
1737 to keep track of what registers are fixed (and not aliased), what registers
1738 are varying in known ways, and what registers are varying in unknown
1741 If both memory references are volatile, then there must always be a
1742 dependence between the two references, since their order can not be
1743 changed. A volatile and non-volatile reference can be interchanged
1746 A MEM_IN_STRUCT reference at a non-AND varying address can never
1747 conflict with a non-MEM_IN_STRUCT reference at a fixed address. We
1748 also must allow AND addresses, because they may generate accesses
1749 outside the object being referenced. This is used to generate
1750 aligned addresses from unaligned addresses, for instance, the alpha
1751 storeqi_unaligned pattern. */
1753 /* Read dependence: X is read after read in MEM takes place. There can
1754 only be a dependence here if both reads are volatile. */
1757 read_dependence (mem
, x
)
1761 return MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
);
1764 /* Returns MEM1 if and only if MEM1 is a scalar at a fixed address and
1765 MEM2 is a reference to a structure at a varying address, or returns
1766 MEM2 if vice versa. Otherwise, returns NULL_RTX. If a non-NULL
1767 value is returned MEM1 and MEM2 can never alias. VARIES_P is used
1768 to decide whether or not an address may vary; it should return
1769 nonzero whenever variation is possible.
1770 MEM1_ADDR and MEM2_ADDR are the addresses of MEM1 and MEM2. */
1773 fixed_scalar_and_varying_struct_p (mem1
, mem2
, mem1_addr
, mem2_addr
, varies_p
)
1775 rtx mem1_addr
, mem2_addr
;
1776 int (*varies_p
) PARAMS ((rtx
, int));
1778 if (! flag_strict_aliasing
)
1781 if (MEM_SCALAR_P (mem1
) && MEM_IN_STRUCT_P (mem2
)
1782 && !varies_p (mem1_addr
, 1) && varies_p (mem2_addr
, 1))
1783 /* MEM1 is a scalar at a fixed address; MEM2 is a struct at a
1787 if (MEM_IN_STRUCT_P (mem1
) && MEM_SCALAR_P (mem2
)
1788 && varies_p (mem1_addr
, 1) && !varies_p (mem2_addr
, 1))
1789 /* MEM2 is a scalar at a fixed address; MEM1 is a struct at a
1796 /* Returns nonzero if something about the mode or address format MEM1
1797 indicates that it might well alias *anything*. */
1800 aliases_everything_p (mem
)
1803 if (GET_CODE (XEXP (mem
, 0)) == AND
)
1804 /* If the address is an AND, its very hard to know at what it is
1805 actually pointing. */
1811 /* Return true if we can determine that the fields referenced cannot
1812 overlap for any pair of objects. */
1815 nonoverlapping_component_refs_p (x
, y
)
1818 tree fieldx
, fieldy
, typex
, typey
, orig_y
;
1822 /* The comparison has to be done at a common type, since we don't
1823 know how the inheritance hierarchy works. */
1827 fieldx
= TREE_OPERAND (x
, 1);
1828 typex
= DECL_FIELD_CONTEXT (fieldx
);
1833 fieldy
= TREE_OPERAND (y
, 1);
1834 typey
= DECL_FIELD_CONTEXT (fieldy
);
1839 y
= TREE_OPERAND (y
, 0);
1841 while (y
&& TREE_CODE (y
) == COMPONENT_REF
);
1843 x
= TREE_OPERAND (x
, 0);
1845 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
1847 /* Never found a common type. */
1851 /* If we're left with accessing different fields of a structure,
1853 if (TREE_CODE (typex
) == RECORD_TYPE
1854 && fieldx
!= fieldy
)
1857 /* The comparison on the current field failed. If we're accessing
1858 a very nested structure, look at the next outer level. */
1859 x
= TREE_OPERAND (x
, 0);
1860 y
= TREE_OPERAND (y
, 0);
1863 && TREE_CODE (x
) == COMPONENT_REF
1864 && TREE_CODE (y
) == COMPONENT_REF
);
1869 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
1872 decl_for_component_ref (x
)
1877 x
= TREE_OPERAND (x
, 0);
1879 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
1881 return x
&& DECL_P (x
) ? x
: NULL_TREE
;
1884 /* Walk up the COMPONENT_REF list and adjust OFFSET to compensate for the
1885 offset of the field reference. */
1888 adjust_offset_for_component_ref (x
, offset
)
1892 HOST_WIDE_INT ioffset
;
1897 ioffset
= INTVAL (offset
);
1900 tree field
= TREE_OPERAND (x
, 1);
1902 if (! host_integerp (DECL_FIELD_OFFSET (field
), 1))
1904 ioffset
+= (tree_low_cst (DECL_FIELD_OFFSET (field
), 1)
1905 + (tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1)
1908 x
= TREE_OPERAND (x
, 0);
1910 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
1912 return GEN_INT (ioffset
);
1915 /* Return nonzero if we can deterimine the exprs corresponding to memrefs
1916 X and Y and they do not overlap. */
1919 nonoverlapping_memrefs_p (x
, y
)
1922 tree exprx
= MEM_EXPR (x
), expry
= MEM_EXPR (y
);
1925 rtx moffsetx
, moffsety
;
1926 HOST_WIDE_INT offsetx
= 0, offsety
= 0, sizex
, sizey
, tem
;
1928 /* Unless both have exprs, we can't tell anything. */
1929 if (exprx
== 0 || expry
== 0)
1932 /* If both are field references, we may be able to determine something. */
1933 if (TREE_CODE (exprx
) == COMPONENT_REF
1934 && TREE_CODE (expry
) == COMPONENT_REF
1935 && nonoverlapping_component_refs_p (exprx
, expry
))
1938 /* If the field reference test failed, look at the DECLs involved. */
1939 moffsetx
= MEM_OFFSET (x
);
1940 if (TREE_CODE (exprx
) == COMPONENT_REF
)
1942 tree t
= decl_for_component_ref (exprx
);
1945 moffsetx
= adjust_offset_for_component_ref (exprx
, moffsetx
);
1948 moffsety
= MEM_OFFSET (y
);
1949 if (TREE_CODE (expry
) == COMPONENT_REF
)
1951 tree t
= decl_for_component_ref (expry
);
1954 moffsety
= adjust_offset_for_component_ref (expry
, moffsety
);
1958 if (! DECL_P (exprx
) || ! DECL_P (expry
))
1961 rtlx
= DECL_RTL (exprx
);
1962 rtly
= DECL_RTL (expry
);
1964 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
1965 can't overlap unless they are the same because we never reuse that part
1966 of the stack frame used for locals for spilled pseudos. */
1967 if ((GET_CODE (rtlx
) != MEM
|| GET_CODE (rtly
) != MEM
)
1968 && ! rtx_equal_p (rtlx
, rtly
))
1971 /* Get the base and offsets of both decls. If either is a register, we
1972 know both are and are the same, so use that as the base. The only
1973 we can avoid overlap is if we can deduce that they are nonoverlapping
1974 pieces of that decl, which is very rare. */
1975 basex
= GET_CODE (rtlx
) == MEM
? XEXP (rtlx
, 0) : rtlx
;
1976 if (GET_CODE (basex
) == PLUS
&& GET_CODE (XEXP (basex
, 1)) == CONST_INT
)
1977 offsetx
= INTVAL (XEXP (basex
, 1)), basex
= XEXP (basex
, 0);
1979 basey
= GET_CODE (rtly
) == MEM
? XEXP (rtly
, 0) : rtly
;
1980 if (GET_CODE (basey
) == PLUS
&& GET_CODE (XEXP (basey
, 1)) == CONST_INT
)
1981 offsety
= INTVAL (XEXP (basey
, 1)), basey
= XEXP (basey
, 0);
1983 /* If the bases are different, we know they do not overlap if both
1984 are constants or if one is a constant and the other a pointer into the
1985 stack frame. Otherwise a different base means we can't tell if they
1987 if (! rtx_equal_p (basex
, basey
))
1988 return ((CONSTANT_P (basex
) && CONSTANT_P (basey
))
1989 || (CONSTANT_P (basex
) && REG_P (basey
)
1990 && REGNO_PTR_FRAME_P (REGNO (basey
)))
1991 || (CONSTANT_P (basey
) && REG_P (basex
)
1992 && REGNO_PTR_FRAME_P (REGNO (basex
))));
1994 sizex
= (GET_CODE (rtlx
) != MEM
? (int) GET_MODE_SIZE (GET_MODE (rtlx
))
1995 : MEM_SIZE (rtlx
) ? INTVAL (MEM_SIZE (rtlx
))
1997 sizey
= (GET_CODE (rtly
) != MEM
? (int) GET_MODE_SIZE (GET_MODE (rtly
))
1998 : MEM_SIZE (rtly
) ? INTVAL (MEM_SIZE (rtly
)) :
2001 /* If we have an offset for either memref, it can update the values computed
2004 offsetx
+= INTVAL (moffsetx
), sizex
-= INTVAL (moffsetx
);
2006 offsety
+= INTVAL (moffsety
), sizey
-= INTVAL (moffsety
);
2008 /* If a memref has both a size and an offset, we can use the smaller size.
2009 We can't do this if the offset isn't known because we must view this
2010 memref as being anywhere inside the DECL's MEM. */
2011 if (MEM_SIZE (x
) && moffsetx
)
2012 sizex
= INTVAL (MEM_SIZE (x
));
2013 if (MEM_SIZE (y
) && moffsety
)
2014 sizey
= INTVAL (MEM_SIZE (y
));
2016 /* Put the values of the memref with the lower offset in X's values. */
2017 if (offsetx
> offsety
)
2019 tem
= offsetx
, offsetx
= offsety
, offsety
= tem
;
2020 tem
= sizex
, sizex
= sizey
, sizey
= tem
;
2023 /* If we don't know the size of the lower-offset value, we can't tell
2024 if they conflict. Otherwise, we do the test. */
2025 return sizex
>= 0 && offsety
>= offsetx
+ sizex
;
2028 /* True dependence: X is read after store in MEM takes place. */
2031 true_dependence (mem
, mem_mode
, x
, varies
)
2033 enum machine_mode mem_mode
;
2035 int (*varies
) PARAMS ((rtx
, int));
2037 rtx x_addr
, mem_addr
;
2040 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2043 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2044 This is used in epilogue deallocation functions. */
2045 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2047 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2050 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
2053 /* Unchanging memory can't conflict with non-unchanging memory.
2054 A non-unchanging read can conflict with a non-unchanging write.
2055 An unchanging read can conflict with an unchanging write since
2056 there may be a single store to this address to initialize it.
2057 Note that an unchanging store can conflict with a non-unchanging read
2058 since we have to make conservative assumptions when we have a
2059 record with readonly fields and we are copying the whole thing.
2060 Just fall through to the code below to resolve potential conflicts.
2061 This won't handle all cases optimally, but the possible performance
2062 loss should be negligible. */
2063 if (RTX_UNCHANGING_P (x
) && ! RTX_UNCHANGING_P (mem
))
2066 if (nonoverlapping_memrefs_p (mem
, x
))
2069 if (mem_mode
== VOIDmode
)
2070 mem_mode
= GET_MODE (mem
);
2072 x_addr
= get_addr (XEXP (x
, 0));
2073 mem_addr
= get_addr (XEXP (mem
, 0));
2075 base
= find_base_term (x_addr
);
2076 if (base
&& (GET_CODE (base
) == LABEL_REF
2077 || (GET_CODE (base
) == SYMBOL_REF
2078 && CONSTANT_POOL_ADDRESS_P (base
))))
2081 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
), mem_mode
))
2084 x_addr
= canon_rtx (x_addr
);
2085 mem_addr
= canon_rtx (mem_addr
);
2087 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
2088 SIZE_FOR_MODE (x
), x_addr
, 0))
2091 if (aliases_everything_p (x
))
2094 /* We cannot use aliases_everything_p to test MEM, since we must look
2095 at MEM_MODE, rather than GET_MODE (MEM). */
2096 if (mem_mode
== QImode
|| GET_CODE (mem_addr
) == AND
)
2099 /* In true_dependence we also allow BLKmode to alias anything. Why
2100 don't we do this in anti_dependence and output_dependence? */
2101 if (mem_mode
== BLKmode
|| GET_MODE (x
) == BLKmode
)
2104 return ! fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
2108 /* Canonical true dependence: X is read after store in MEM takes place.
2109 Variant of true_dependence which assumes MEM has already been
2110 canonicalized (hence we no longer do that here).
2111 The mem_addr argument has been added, since true_dependence computed
2112 this value prior to canonicalizing. */
2115 canon_true_dependence (mem
, mem_mode
, mem_addr
, x
, varies
)
2116 rtx mem
, mem_addr
, x
;
2117 enum machine_mode mem_mode
;
2118 int (*varies
) PARAMS ((rtx
, int));
2122 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2125 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2126 This is used in epilogue deallocation functions. */
2127 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2129 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2132 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
2135 /* If X is an unchanging read, then it can't possibly conflict with any
2136 non-unchanging store. It may conflict with an unchanging write though,
2137 because there may be a single store to this address to initialize it.
2138 Just fall through to the code below to resolve the case where we have
2139 both an unchanging read and an unchanging write. This won't handle all
2140 cases optimally, but the possible performance loss should be
2142 if (RTX_UNCHANGING_P (x
) && ! RTX_UNCHANGING_P (mem
))
2145 if (nonoverlapping_memrefs_p (x
, mem
))
2148 x_addr
= get_addr (XEXP (x
, 0));
2150 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
), mem_mode
))
2153 x_addr
= canon_rtx (x_addr
);
2154 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
2155 SIZE_FOR_MODE (x
), x_addr
, 0))
2158 if (aliases_everything_p (x
))
2161 /* We cannot use aliases_everything_p to test MEM, since we must look
2162 at MEM_MODE, rather than GET_MODE (MEM). */
2163 if (mem_mode
== QImode
|| GET_CODE (mem_addr
) == AND
)
2166 /* In true_dependence we also allow BLKmode to alias anything. Why
2167 don't we do this in anti_dependence and output_dependence? */
2168 if (mem_mode
== BLKmode
|| GET_MODE (x
) == BLKmode
)
2171 return ! fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
2175 /* Returns non-zero if a write to X might alias a previous read from
2176 (or, if WRITEP is non-zero, a write to) MEM. */
2179 write_dependence_p (mem
, x
, writep
)
2184 rtx x_addr
, mem_addr
;
2188 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2191 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2192 This is used in epilogue deallocation functions. */
2193 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2195 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2198 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
2201 /* Unchanging memory can't conflict with non-unchanging memory. */
2202 if (RTX_UNCHANGING_P (x
) != RTX_UNCHANGING_P (mem
))
2205 /* If MEM is an unchanging read, then it can't possibly conflict with
2206 the store to X, because there is at most one store to MEM, and it must
2207 have occurred somewhere before MEM. */
2208 if (! writep
&& RTX_UNCHANGING_P (mem
))
2211 if (nonoverlapping_memrefs_p (x
, mem
))
2214 x_addr
= get_addr (XEXP (x
, 0));
2215 mem_addr
= get_addr (XEXP (mem
, 0));
2219 base
= find_base_term (mem_addr
);
2220 if (base
&& (GET_CODE (base
) == LABEL_REF
2221 || (GET_CODE (base
) == SYMBOL_REF
2222 && CONSTANT_POOL_ADDRESS_P (base
))))
2226 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
),
2230 x_addr
= canon_rtx (x_addr
);
2231 mem_addr
= canon_rtx (mem_addr
);
2233 if (!memrefs_conflict_p (SIZE_FOR_MODE (mem
), mem_addr
,
2234 SIZE_FOR_MODE (x
), x_addr
, 0))
2238 = fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
2241 return (!(fixed_scalar
== mem
&& !aliases_everything_p (x
))
2242 && !(fixed_scalar
== x
&& !aliases_everything_p (mem
)));
2245 /* Anti dependence: X is written after read in MEM takes place. */
2248 anti_dependence (mem
, x
)
2252 return write_dependence_p (mem
, x
, /*writep=*/0);
2255 /* Output dependence: X is written after store in MEM takes place. */
2258 output_dependence (mem
, x
)
2262 return write_dependence_p (mem
, x
, /*writep=*/1);
2265 /* A subroutine of nonlocal_mentioned_p, returns 1 if *LOC mentions
2266 something which is not local to the function and is not constant. */
2269 nonlocal_mentioned_p_1 (loc
, data
)
2271 void *data ATTRIBUTE_UNUSED
;
2280 switch (GET_CODE (x
))
2283 if (GET_CODE (SUBREG_REG (x
)) == REG
)
2285 /* Global registers are not local. */
2286 if (REGNO (SUBREG_REG (x
)) < FIRST_PSEUDO_REGISTER
2287 && global_regs
[subreg_regno (x
)])
2295 /* Global registers are not local. */
2296 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2311 /* Constants in the function's constants pool are constant. */
2312 if (CONSTANT_POOL_ADDRESS_P (x
))
2317 /* Non-constant calls and recursion are not local. */
2321 /* Be overly conservative and consider any volatile memory
2322 reference as not local. */
2323 if (MEM_VOLATILE_P (x
))
2325 base
= find_base_term (XEXP (x
, 0));
2328 /* A Pmode ADDRESS could be a reference via the structure value
2329 address or static chain. Such memory references are nonlocal.
2331 Thus, we have to examine the contents of the ADDRESS to find
2332 out if this is a local reference or not. */
2333 if (GET_CODE (base
) == ADDRESS
2334 && GET_MODE (base
) == Pmode
2335 && (XEXP (base
, 0) == stack_pointer_rtx
2336 || XEXP (base
, 0) == arg_pointer_rtx
2337 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2338 || XEXP (base
, 0) == hard_frame_pointer_rtx
2340 || XEXP (base
, 0) == frame_pointer_rtx
))
2342 /* Constants in the function's constant pool are constant. */
2343 if (GET_CODE (base
) == SYMBOL_REF
&& CONSTANT_POOL_ADDRESS_P (base
))
2348 case UNSPEC_VOLATILE
:
2353 if (MEM_VOLATILE_P (x
))
2365 /* Returns non-zero if X might mention something which is not
2366 local to the function and is not constant. */
2369 nonlocal_mentioned_p (x
)
2375 if (GET_CODE (x
) == CALL_INSN
)
2377 if (! CONST_OR_PURE_CALL_P (x
))
2379 x
= CALL_INSN_FUNCTION_USAGE (x
);
2387 return for_each_rtx (&x
, nonlocal_mentioned_p_1
, NULL
);
2390 /* A subroutine of nonlocal_referenced_p, returns 1 if *LOC references
2391 something which is not local to the function and is not constant. */
2394 nonlocal_referenced_p_1 (loc
, data
)
2396 void *data ATTRIBUTE_UNUSED
;
2403 switch (GET_CODE (x
))
2409 return nonlocal_mentioned_p (x
);
2412 /* Non-constant calls and recursion are not local. */
2416 if (nonlocal_mentioned_p (SET_SRC (x
)))
2419 if (GET_CODE (SET_DEST (x
)) == MEM
)
2420 return nonlocal_mentioned_p (XEXP (SET_DEST (x
), 0));
2422 /* If the destination is anything other than a CC0, PC,
2423 MEM, REG, or a SUBREG of a REG that occupies all of
2424 the REG, then X references nonlocal memory if it is
2425 mentioned in the destination. */
2426 if (GET_CODE (SET_DEST (x
)) != CC0
2427 && GET_CODE (SET_DEST (x
)) != PC
2428 && GET_CODE (SET_DEST (x
)) != REG
2429 && ! (GET_CODE (SET_DEST (x
)) == SUBREG
2430 && GET_CODE (SUBREG_REG (SET_DEST (x
))) == REG
2431 && (((GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (x
))))
2432 + (UNITS_PER_WORD
- 1)) / UNITS_PER_WORD
)
2433 == ((GET_MODE_SIZE (GET_MODE (SET_DEST (x
)))
2434 + (UNITS_PER_WORD
- 1)) / UNITS_PER_WORD
))))
2435 return nonlocal_mentioned_p (SET_DEST (x
));
2439 if (GET_CODE (XEXP (x
, 0)) == MEM
)
2440 return nonlocal_mentioned_p (XEXP (XEXP (x
, 0), 0));
2444 return nonlocal_mentioned_p (XEXP (x
, 0));
2447 case UNSPEC_VOLATILE
:
2451 if (MEM_VOLATILE_P (x
))
2463 /* Returns non-zero if X might reference something which is not
2464 local to the function and is not constant. */
2467 nonlocal_referenced_p (x
)
2473 if (GET_CODE (x
) == CALL_INSN
)
2475 if (! CONST_OR_PURE_CALL_P (x
))
2477 x
= CALL_INSN_FUNCTION_USAGE (x
);
2485 return for_each_rtx (&x
, nonlocal_referenced_p_1
, NULL
);
2488 /* A subroutine of nonlocal_set_p, returns 1 if *LOC sets
2489 something which is not local to the function and is not constant. */
2492 nonlocal_set_p_1 (loc
, data
)
2494 void *data ATTRIBUTE_UNUSED
;
2501 switch (GET_CODE (x
))
2504 /* Non-constant calls and recursion are not local. */
2513 return nonlocal_mentioned_p (XEXP (x
, 0));
2516 if (nonlocal_mentioned_p (SET_DEST (x
)))
2518 return nonlocal_set_p (SET_SRC (x
));
2521 return nonlocal_mentioned_p (XEXP (x
, 0));
2527 case UNSPEC_VOLATILE
:
2531 if (MEM_VOLATILE_P (x
))
2543 /* Returns non-zero if X might set something which is not
2544 local to the function and is not constant. */
2553 if (GET_CODE (x
) == CALL_INSN
)
2555 if (! CONST_OR_PURE_CALL_P (x
))
2557 x
= CALL_INSN_FUNCTION_USAGE (x
);
2565 return for_each_rtx (&x
, nonlocal_set_p_1
, NULL
);
2568 /* Mark the function if it is constant. */
2571 mark_constant_function ()
2574 int nonlocal_memory_referenced
;
2576 if (TREE_READONLY (current_function_decl
)
2577 || DECL_IS_PURE (current_function_decl
)
2578 || TREE_THIS_VOLATILE (current_function_decl
)
2579 || TYPE_MODE (TREE_TYPE (current_function_decl
)) == VOIDmode
2580 || current_function_has_nonlocal_goto
2581 || !(*targetm
.binds_local_p
) (current_function_decl
))
2584 /* A loop might not return which counts as a side effect. */
2585 if (mark_dfs_back_edges ())
2588 nonlocal_memory_referenced
= 0;
2590 init_alias_analysis ();
2592 /* Determine if this is a constant or pure function. */
2594 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
2596 if (! INSN_P (insn
))
2599 if (nonlocal_set_p (insn
) || global_reg_mentioned_p (insn
)
2600 || volatile_refs_p (PATTERN (insn
)))
2603 if (! nonlocal_memory_referenced
)
2604 nonlocal_memory_referenced
= nonlocal_referenced_p (insn
);
2607 end_alias_analysis ();
2609 /* Mark the function. */
2613 else if (nonlocal_memory_referenced
)
2614 DECL_IS_PURE (current_function_decl
) = 1;
2616 TREE_READONLY (current_function_decl
) = 1;
2620 static HARD_REG_SET argument_registers
;
2627 #ifndef OUTGOING_REGNO
2628 #define OUTGOING_REGNO(N) N
2630 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2631 /* Check whether this register can hold an incoming pointer
2632 argument. FUNCTION_ARG_REGNO_P tests outgoing register
2633 numbers, so translate if necessary due to register windows. */
2634 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i
))
2635 && HARD_REGNO_MODE_OK (i
, Pmode
))
2636 SET_HARD_REG_BIT (argument_registers
, i
);
2638 alias_sets
= splay_tree_new (splay_tree_compare_ints
, 0, 0);
2641 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
2645 init_alias_analysis ()
2647 int maxreg
= max_reg_num ();
2653 reg_known_value_size
= maxreg
;
2656 = (rtx
*) xcalloc ((maxreg
- FIRST_PSEUDO_REGISTER
), sizeof (rtx
))
2657 - FIRST_PSEUDO_REGISTER
;
2659 = (char*) xcalloc ((maxreg
- FIRST_PSEUDO_REGISTER
), sizeof (char))
2660 - FIRST_PSEUDO_REGISTER
;
2662 /* Overallocate reg_base_value to allow some growth during loop
2663 optimization. Loop unrolling can create a large number of
2665 reg_base_value_size
= maxreg
* 2;
2666 reg_base_value
= (rtx
*) ggc_alloc_cleared (reg_base_value_size
2669 new_reg_base_value
= (rtx
*) xmalloc (reg_base_value_size
* sizeof (rtx
));
2670 reg_seen
= (char *) xmalloc (reg_base_value_size
);
2671 if (! reload_completed
&& flag_unroll_loops
)
2673 /* ??? Why are we realloc'ing if we're just going to zero it? */
2674 alias_invariant
= (rtx
*)xrealloc (alias_invariant
,
2675 reg_base_value_size
* sizeof (rtx
));
2676 memset ((char *)alias_invariant
, 0, reg_base_value_size
* sizeof (rtx
));
2679 /* The basic idea is that each pass through this loop will use the
2680 "constant" information from the previous pass to propagate alias
2681 information through another level of assignments.
2683 This could get expensive if the assignment chains are long. Maybe
2684 we should throttle the number of iterations, possibly based on
2685 the optimization level or flag_expensive_optimizations.
2687 We could propagate more information in the first pass by making use
2688 of REG_N_SETS to determine immediately that the alias information
2689 for a pseudo is "constant".
2691 A program with an uninitialized variable can cause an infinite loop
2692 here. Instead of doing a full dataflow analysis to detect such problems
2693 we just cap the number of iterations for the loop.
2695 The state of the arrays for the set chain in question does not matter
2696 since the program has undefined behavior. */
2701 /* Assume nothing will change this iteration of the loop. */
2704 /* We want to assign the same IDs each iteration of this loop, so
2705 start counting from zero each iteration of the loop. */
2708 /* We're at the start of the function each iteration through the
2709 loop, so we're copying arguments. */
2710 copying_arguments
= 1;
2712 /* Wipe the potential alias information clean for this pass. */
2713 memset ((char *) new_reg_base_value
, 0, reg_base_value_size
* sizeof (rtx
));
2715 /* Wipe the reg_seen array clean. */
2716 memset ((char *) reg_seen
, 0, reg_base_value_size
);
2718 /* Mark all hard registers which may contain an address.
2719 The stack, frame and argument pointers may contain an address.
2720 An argument register which can hold a Pmode value may contain
2721 an address even if it is not in BASE_REGS.
2723 The address expression is VOIDmode for an argument and
2724 Pmode for other registers. */
2726 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2727 if (TEST_HARD_REG_BIT (argument_registers
, i
))
2728 new_reg_base_value
[i
] = gen_rtx_ADDRESS (VOIDmode
,
2729 gen_rtx_REG (Pmode
, i
));
2731 new_reg_base_value
[STACK_POINTER_REGNUM
]
2732 = gen_rtx_ADDRESS (Pmode
, stack_pointer_rtx
);
2733 new_reg_base_value
[ARG_POINTER_REGNUM
]
2734 = gen_rtx_ADDRESS (Pmode
, arg_pointer_rtx
);
2735 new_reg_base_value
[FRAME_POINTER_REGNUM
]
2736 = gen_rtx_ADDRESS (Pmode
, frame_pointer_rtx
);
2737 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2738 new_reg_base_value
[HARD_FRAME_POINTER_REGNUM
]
2739 = gen_rtx_ADDRESS (Pmode
, hard_frame_pointer_rtx
);
2742 /* Walk the insns adding values to the new_reg_base_value array. */
2743 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
2749 #if defined (HAVE_prologue) || defined (HAVE_epilogue)
2750 /* The prologue/epilogue insns are not threaded onto the
2751 insn chain until after reload has completed. Thus,
2752 there is no sense wasting time checking if INSN is in
2753 the prologue/epilogue until after reload has completed. */
2754 if (reload_completed
2755 && prologue_epilogue_contains (insn
))
2759 /* If this insn has a noalias note, process it, Otherwise,
2760 scan for sets. A simple set will have no side effects
2761 which could change the base value of any other register. */
2763 if (GET_CODE (PATTERN (insn
)) == SET
2764 && REG_NOTES (insn
) != 0
2765 && find_reg_note (insn
, REG_NOALIAS
, NULL_RTX
))
2766 record_set (SET_DEST (PATTERN (insn
)), NULL_RTX
, NULL
);
2768 note_stores (PATTERN (insn
), record_set
, NULL
);
2770 set
= single_set (insn
);
2773 && GET_CODE (SET_DEST (set
)) == REG
2774 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
)
2776 unsigned int regno
= REGNO (SET_DEST (set
));
2777 rtx src
= SET_SRC (set
);
2779 if (REG_NOTES (insn
) != 0
2780 && (((note
= find_reg_note (insn
, REG_EQUAL
, 0)) != 0
2781 && REG_N_SETS (regno
) == 1)
2782 || (note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) != 0)
2783 && GET_CODE (XEXP (note
, 0)) != EXPR_LIST
2784 && ! rtx_varies_p (XEXP (note
, 0), 1)
2785 && ! reg_overlap_mentioned_p (SET_DEST (set
), XEXP (note
, 0)))
2787 reg_known_value
[regno
] = XEXP (note
, 0);
2788 reg_known_equiv_p
[regno
] = REG_NOTE_KIND (note
) == REG_EQUIV
;
2790 else if (REG_N_SETS (regno
) == 1
2791 && GET_CODE (src
) == PLUS
2792 && GET_CODE (XEXP (src
, 0)) == REG
2793 && REGNO (XEXP (src
, 0)) >= FIRST_PSEUDO_REGISTER
2794 && (reg_known_value
[REGNO (XEXP (src
, 0))])
2795 && GET_CODE (XEXP (src
, 1)) == CONST_INT
)
2797 rtx op0
= XEXP (src
, 0);
2798 op0
= reg_known_value
[REGNO (op0
)];
2799 reg_known_value
[regno
]
2800 = plus_constant (op0
, INTVAL (XEXP (src
, 1)));
2801 reg_known_equiv_p
[regno
] = 0;
2803 else if (REG_N_SETS (regno
) == 1
2804 && ! rtx_varies_p (src
, 1))
2806 reg_known_value
[regno
] = src
;
2807 reg_known_equiv_p
[regno
] = 0;
2811 else if (GET_CODE (insn
) == NOTE
2812 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_BEG
)
2813 copying_arguments
= 0;
2816 /* Now propagate values from new_reg_base_value to reg_base_value. */
2817 for (ui
= 0; ui
< reg_base_value_size
; ui
++)
2819 if (new_reg_base_value
[ui
]
2820 && new_reg_base_value
[ui
] != reg_base_value
[ui
]
2821 && ! rtx_equal_p (new_reg_base_value
[ui
], reg_base_value
[ui
]))
2823 reg_base_value
[ui
] = new_reg_base_value
[ui
];
2828 while (changed
&& ++pass
< MAX_ALIAS_LOOP_PASSES
);
2830 /* Fill in the remaining entries. */
2831 for (i
= FIRST_PSEUDO_REGISTER
; i
< maxreg
; i
++)
2832 if (reg_known_value
[i
] == 0)
2833 reg_known_value
[i
] = regno_reg_rtx
[i
];
2835 /* Simplify the reg_base_value array so that no register refers to
2836 another register, except to special registers indirectly through
2837 ADDRESS expressions.
2839 In theory this loop can take as long as O(registers^2), but unless
2840 there are very long dependency chains it will run in close to linear
2843 This loop may not be needed any longer now that the main loop does
2844 a better job at propagating alias information. */
2850 for (ui
= 0; ui
< reg_base_value_size
; ui
++)
2852 rtx base
= reg_base_value
[ui
];
2853 if (base
&& GET_CODE (base
) == REG
)
2855 unsigned int base_regno
= REGNO (base
);
2856 if (base_regno
== ui
) /* register set from itself */
2857 reg_base_value
[ui
] = 0;
2859 reg_base_value
[ui
] = reg_base_value
[base_regno
];
2864 while (changed
&& pass
< MAX_ALIAS_LOOP_PASSES
);
2867 free (new_reg_base_value
);
2868 new_reg_base_value
= 0;
2874 end_alias_analysis ()
2876 free (reg_known_value
+ FIRST_PSEUDO_REGISTER
);
2877 reg_known_value
= 0;
2878 reg_known_value_size
= 0;
2879 free (reg_known_equiv_p
+ FIRST_PSEUDO_REGISTER
);
2880 reg_known_equiv_p
= 0;
2882 reg_base_value_size
= 0;
2883 if (alias_invariant
)
2885 free (alias_invariant
);
2886 alias_invariant
= 0;
2890 #include "gt-alias.h"