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"
39 /* The alias sets assigned to MEMs assist the back-end in determining
40 which MEMs can alias which other MEMs. In general, two MEMs in
41 different alias sets cannot alias each other, with one important
42 exception. Consider something like:
44 struct S {int i; double d; };
46 a store to an `S' can alias something of either type `int' or type
47 `double'. (However, a store to an `int' cannot alias a `double'
48 and vice versa.) We indicate this via a tree structure that looks
56 (The arrows are directed and point downwards.)
57 In this situation we say the alias set for `struct S' is the
58 `superset' and that those for `int' and `double' are `subsets'.
60 To see whether two alias sets can point to the same memory, we must
61 see if either alias set is a subset of the other. We need not trace
62 past immediate descendents, however, since we propagate all
63 grandchildren up one level.
65 Alias set zero is implicitly a superset of all other alias sets.
66 However, this is no actual entry for alias set zero. It is an
67 error to attempt to explicitly construct a subset of zero. */
69 typedef struct alias_set_entry
71 /* The alias set number, as stored in MEM_ALIAS_SET. */
72 HOST_WIDE_INT alias_set
;
74 /* The children of the alias set. These are not just the immediate
75 children, but, in fact, all descendents. So, if we have:
77 struct T { struct S s; float f; }
79 continuing our example above, the children here will be all of
80 `int', `double', `float', and `struct S'. */
83 /* Nonzero if would have a child of zero: this effectively makes this
84 alias set the same as alias set zero. */
88 static int rtx_equal_for_memref_p
PARAMS ((rtx
, rtx
));
89 static rtx find_symbolic_term
PARAMS ((rtx
));
90 rtx get_addr
PARAMS ((rtx
));
91 static int memrefs_conflict_p
PARAMS ((int, rtx
, int, rtx
,
93 static void record_set
PARAMS ((rtx
, rtx
, void *));
94 static rtx find_base_term
PARAMS ((rtx
));
95 static int base_alias_check
PARAMS ((rtx
, rtx
, enum machine_mode
,
97 static int handled_component_p
PARAMS ((tree
));
98 static int can_address_p
PARAMS ((tree
));
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 int write_dependence_p
PARAMS ((rtx
, rtx
, int));
108 static int nonlocal_mentioned_p
PARAMS ((rtx
));
110 /* Set up all info needed to perform alias analysis on memory references. */
112 /* Returns the size in bytes of the mode of X. */
113 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
115 /* Returns nonzero if MEM1 and MEM2 do not alias because they are in
116 different alias sets. We ignore alias sets in functions making use
117 of variable arguments because the va_arg macros on some systems are
119 #define DIFFERENT_ALIAS_SETS_P(MEM1, MEM2) \
120 mems_in_disjoint_alias_sets_p (MEM1, MEM2)
122 /* Cap the number of passes we make over the insns propagating alias
123 information through set chains. 10 is a completely arbitrary choice. */
124 #define MAX_ALIAS_LOOP_PASSES 10
126 /* reg_base_value[N] gives an address to which register N is related.
127 If all sets after the first add or subtract to the current value
128 or otherwise modify it so it does not point to a different top level
129 object, reg_base_value[N] is equal to the address part of the source
132 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
133 expressions represent certain special values: function arguments and
134 the stack, frame, and argument pointers.
136 The contents of an ADDRESS is not normally used, the mode of the
137 ADDRESS determines whether the ADDRESS is a function argument or some
138 other special value. Pointer equality, not rtx_equal_p, determines whether
139 two ADDRESS expressions refer to the same base address.
141 The only use of the contents of an ADDRESS is for determining if the
142 current function performs nonlocal memory memory references for the
143 purposes of marking the function as a constant function. */
145 static rtx
*reg_base_value
;
146 static rtx
*new_reg_base_value
;
147 static unsigned int reg_base_value_size
; /* size of reg_base_value array */
149 #define REG_BASE_VALUE(X) \
150 (REGNO (X) < reg_base_value_size \
151 ? reg_base_value[REGNO (X)] : 0)
153 /* Vector of known invariant relationships between registers. Set in
154 loop unrolling. Indexed by register number, if nonzero the value
155 is an expression describing this register in terms of another.
157 The length of this array is REG_BASE_VALUE_SIZE.
159 Because this array contains only pseudo registers it has no effect
161 static rtx
*alias_invariant
;
163 /* Vector indexed by N giving the initial (unchanging) value known for
164 pseudo-register N. This array is initialized in
165 init_alias_analysis, and does not change until end_alias_analysis
167 rtx
*reg_known_value
;
169 /* Indicates number of valid entries in reg_known_value. */
170 static unsigned int reg_known_value_size
;
172 /* Vector recording for each reg_known_value whether it is due to a
173 REG_EQUIV note. Future passes (viz., reload) may replace the
174 pseudo with the equivalent expression and so we account for the
175 dependences that would be introduced if that happens.
177 The REG_EQUIV notes created in assign_parms may mention the arg
178 pointer, and there are explicit insns in the RTL that modify the
179 arg pointer. Thus we must ensure that such insns don't get
180 scheduled across each other because that would invalidate the
181 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
182 wrong, but solving the problem in the scheduler will likely give
183 better code, so we do it here. */
184 char *reg_known_equiv_p
;
186 /* True when scanning insns from the start of the rtl to the
187 NOTE_INSN_FUNCTION_BEG note. */
188 static int copying_arguments
;
190 /* The splay-tree used to store the various alias set entries. */
191 static splay_tree alias_sets
;
193 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
194 such an entry, or NULL otherwise. */
196 static alias_set_entry
197 get_alias_set_entry (alias_set
)
198 HOST_WIDE_INT alias_set
;
201 = splay_tree_lookup (alias_sets
, (splay_tree_key
) alias_set
);
203 return sn
!= 0 ? ((alias_set_entry
) sn
->value
) : 0;
206 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
207 the two MEMs cannot alias each other. */
210 mems_in_disjoint_alias_sets_p (mem1
, mem2
)
214 #ifdef ENABLE_CHECKING
215 /* Perform a basic sanity check. Namely, that there are no alias sets
216 if we're not using strict aliasing. This helps to catch bugs
217 whereby someone uses PUT_CODE, but doesn't clear MEM_ALIAS_SET, or
218 where a MEM is allocated in some way other than by the use of
219 gen_rtx_MEM, and the MEM_ALIAS_SET is not cleared. If we begin to
220 use alias sets to indicate that spilled registers cannot alias each
221 other, we might need to remove this check. */
222 if (! flag_strict_aliasing
223 && (MEM_ALIAS_SET (mem1
) != 0 || MEM_ALIAS_SET (mem2
) != 0))
227 return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1
), MEM_ALIAS_SET (mem2
));
230 /* Insert the NODE into the splay tree given by DATA. Used by
231 record_alias_subset via splay_tree_foreach. */
234 insert_subset_children (node
, data
)
235 splay_tree_node node
;
238 splay_tree_insert ((splay_tree
) data
, node
->key
, node
->value
);
243 /* Return 1 if the two specified alias sets may conflict. */
246 alias_sets_conflict_p (set1
, set2
)
247 HOST_WIDE_INT set1
, set2
;
251 /* If have no alias set information for one of the operands, we have
252 to assume it can alias anything. */
253 if (set1
== 0 || set2
== 0
254 /* If the two alias sets are the same, they may alias. */
258 /* See if the first alias set is a subset of the second. */
259 ase
= get_alias_set_entry (set1
);
261 && (ase
->has_zero_child
262 || splay_tree_lookup (ase
->children
,
263 (splay_tree_key
) set2
)))
266 /* Now do the same, but with the alias sets reversed. */
267 ase
= get_alias_set_entry (set2
);
269 && (ase
->has_zero_child
270 || splay_tree_lookup (ase
->children
,
271 (splay_tree_key
) set1
)))
274 /* The two alias sets are distinct and neither one is the
275 child of the other. Therefore, they cannot alias. */
279 /* Return 1 if TYPE is a RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE and has
280 has any readonly fields. If any of the fields have types that
281 contain readonly fields, return true as well. */
284 readonly_fields_p (type
)
289 if (TREE_CODE (type
) != RECORD_TYPE
&& TREE_CODE (type
) != UNION_TYPE
290 && TREE_CODE (type
) != QUAL_UNION_TYPE
)
293 for (field
= TYPE_FIELDS (type
); field
!= 0; field
= TREE_CHAIN (field
))
294 if (TREE_CODE (field
) == FIELD_DECL
295 && (TREE_READONLY (field
)
296 || readonly_fields_p (TREE_TYPE (field
))))
302 /* Return 1 if any MEM object of type T1 will always conflict (using the
303 dependency routines in this file) with any MEM object of type T2.
304 This is used when allocating temporary storage. If T1 and/or T2 are
305 NULL_TREE, it means we know nothing about the storage. */
308 objects_must_conflict_p (t1
, t2
)
311 /* If neither has a type specified, we don't know if they'll conflict
312 because we may be using them to store objects of various types, for
313 example the argument and local variables areas of inlined functions. */
314 if (t1
== 0 && t2
== 0)
317 /* If one or the other has readonly fields or is readonly,
318 then they may not conflict. */
319 if ((t1
!= 0 && readonly_fields_p (t1
))
320 || (t2
!= 0 && readonly_fields_p (t2
))
321 || (t1
!= 0 && TYPE_READONLY (t1
))
322 || (t2
!= 0 && TYPE_READONLY (t2
)))
325 /* If they are the same type, they must conflict. */
327 /* Likewise if both are volatile. */
328 || (t1
!= 0 && TYPE_VOLATILE (t1
) && t2
!= 0 && TYPE_VOLATILE (t2
)))
331 /* If one is aggregate and the other is scalar then they may not
333 if ((t1
!= 0 && AGGREGATE_TYPE_P (t1
))
334 != (t2
!= 0 && AGGREGATE_TYPE_P (t2
)))
337 /* Otherwise they conflict only if the alias sets conflict. */
338 return alias_sets_conflict_p (t1
? get_alias_set (t1
) : 0,
339 t2
? get_alias_set (t2
) : 0);
342 /* T is an expression with pointer type. Find the DECL on which this
343 expression is based. (For example, in `a[i]' this would be `a'.)
344 If there is no such DECL, or a unique decl cannot be determined,
345 NULL_TREE is retured. */
353 if (t
== 0 || t
== error_mark_node
|| ! POINTER_TYPE_P (TREE_TYPE (t
)))
356 /* If this is a declaration, return it. */
357 if (TREE_CODE_CLASS (TREE_CODE (t
)) == 'd')
360 /* Handle general expressions. It would be nice to deal with
361 COMPONENT_REFs here. If we could tell that `a' and `b' were the
362 same, then `a->f' and `b->f' are also the same. */
363 switch (TREE_CODE_CLASS (TREE_CODE (t
)))
366 return find_base_decl (TREE_OPERAND (t
, 0));
369 /* Return 0 if found in neither or both are the same. */
370 d0
= find_base_decl (TREE_OPERAND (t
, 0));
371 d1
= find_base_decl (TREE_OPERAND (t
, 1));
382 d0
= find_base_decl (TREE_OPERAND (t
, 0));
383 d1
= find_base_decl (TREE_OPERAND (t
, 1));
384 d2
= find_base_decl (TREE_OPERAND (t
, 2));
386 /* Set any nonzero values from the last, then from the first. */
387 if (d1
== 0) d1
= d2
;
388 if (d0
== 0) d0
= d1
;
389 if (d1
== 0) d1
= d0
;
390 if (d2
== 0) d2
= d1
;
392 /* At this point all are nonzero or all are zero. If all three are the
393 same, return it. Otherwise, return zero. */
394 return (d0
== d1
&& d1
== d2
) ? d0
: 0;
401 /* Return 1 if T is an expression that get_inner_reference handles. */
404 handled_component_p (t
)
407 switch (TREE_CODE (t
))
412 case ARRAY_RANGE_REF
:
413 case NON_LVALUE_EXPR
:
418 return (TYPE_MODE (TREE_TYPE (t
))
419 == TYPE_MODE (TREE_TYPE (TREE_OPERAND (t
, 0))));
426 /* Return 1 if all the nested component references handled by
427 get_inner_reference in T are such that we can address the object in T. */
433 /* If we're at the end, it is vacuously addressable. */
434 if (! handled_component_p (t
))
437 /* Bitfields are never addressable. */
438 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
441 else if (TREE_CODE (t
) == COMPONENT_REF
442 && ! DECL_NONADDRESSABLE_P (TREE_OPERAND (t
, 1))
443 && can_address_p (TREE_OPERAND (t
, 0)))
446 else if ((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
447 && ! TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t
, 0)))
448 && can_address_p (TREE_OPERAND (t
, 0)))
454 /* Return the alias set for T, which may be either a type or an
455 expression. Call language-specific routine for help, if needed. */
463 /* If we're not doing any alias analysis, just assume everything
464 aliases everything else. Also return 0 if this or its type is
466 if (! flag_strict_aliasing
|| t
== error_mark_node
468 && (TREE_TYPE (t
) == 0 || TREE_TYPE (t
) == error_mark_node
)))
471 /* We can be passed either an expression or a type. This and the
472 language-specific routine may make mutually-recursive calls to each other
473 to figure out what to do. At each juncture, we see if this is a tree
474 that the language may need to handle specially. First handle things that
479 tree placeholder_ptr
= 0;
481 /* First see if the actual object referenced is an INDIRECT_REF from a
482 restrict-qualified pointer or a "void *". Start by removing nops
483 since we care only about the actual object. Also replace
484 PLACEHOLDER_EXPRs. */
485 while (((TREE_CODE (inner
) == NOP_EXPR
486 || TREE_CODE (inner
) == CONVERT_EXPR
)
487 && (TYPE_MODE (TREE_TYPE (inner
))
488 == TYPE_MODE (TREE_TYPE (TREE_OPERAND (inner
, 0)))))
489 || TREE_CODE (inner
) == NON_LVALUE_EXPR
490 || TREE_CODE (inner
) == PLACEHOLDER_EXPR
491 || handled_component_p (inner
))
493 if (TREE_CODE (inner
) == PLACEHOLDER_EXPR
)
494 inner
= find_placeholder (inner
, &placeholder_ptr
);
496 inner
= TREE_OPERAND (inner
, 0);
499 /* Check for accesses through restrict-qualified pointers. */
500 if (TREE_CODE (inner
) == INDIRECT_REF
)
502 tree decl
= find_base_decl (TREE_OPERAND (inner
, 0));
504 if (decl
&& DECL_POINTER_ALIAS_SET_KNOWN_P (decl
))
506 /* If we haven't computed the actual alias set, do it now. */
507 if (DECL_POINTER_ALIAS_SET (decl
) == -2)
509 /* No two restricted pointers can point at the same thing.
510 However, a restricted pointer can point at the same thing
511 as an unrestricted pointer, if that unrestricted pointer
512 is based on the restricted pointer. So, we make the
513 alias set for the restricted pointer a subset of the
514 alias set for the type pointed to by the type of the
516 HOST_WIDE_INT pointed_to_alias_set
517 = get_alias_set (TREE_TYPE (TREE_TYPE (decl
)));
519 if (pointed_to_alias_set
== 0)
520 /* It's not legal to make a subset of alias set zero. */
524 DECL_POINTER_ALIAS_SET (decl
) = new_alias_set ();
525 record_alias_subset (pointed_to_alias_set
,
526 DECL_POINTER_ALIAS_SET (decl
));
530 /* We use the alias set indicated in the declaration. */
531 return DECL_POINTER_ALIAS_SET (decl
);
534 /* If we have an INDIRECT_REF via a void pointer, we don't
535 know anything about what that might alias. */
536 else if (TREE_CODE (TREE_TYPE (inner
)) == VOID_TYPE
)
540 /* Otherwise, pick up the outermost object that we could have a pointer
541 to, processing conversion and PLACEHOLDER_EXPR as above. */
543 while (((TREE_CODE (t
) == NOP_EXPR
|| TREE_CODE (t
) == CONVERT_EXPR
)
544 && (TYPE_MODE (TREE_TYPE (t
))
545 == TYPE_MODE (TREE_TYPE (TREE_OPERAND (t
, 0)))))
546 || TREE_CODE (t
) == NON_LVALUE_EXPR
547 || TREE_CODE (t
) == PLACEHOLDER_EXPR
548 || (handled_component_p (t
) && ! can_address_p (t
)))
550 /* Give the language a chance to do something with this tree
551 before we go inside it. */
552 if ((set
= lang_get_alias_set (t
)) != -1)
555 if (TREE_CODE (t
) == PLACEHOLDER_EXPR
)
556 t
= find_placeholder (t
, &placeholder_ptr
);
558 t
= TREE_OPERAND (t
, 0);
561 /* Give the language another chance to do something. */
562 if ((set
= lang_get_alias_set (t
)) != -1)
565 /* If we've already determined the alias set for a decl, just return
566 it. This is necessary for C++ anonymous unions, whose component
567 variables don't look like union members (boo!). */
568 if (TREE_CODE (t
) == VAR_DECL
569 && DECL_RTL_SET_P (t
) && GET_CODE (DECL_RTL (t
)) == MEM
)
570 return MEM_ALIAS_SET (DECL_RTL (t
));
572 /* Now all we care about is the type. */
576 /* Variant qualifiers don't affect the alias set, so get the main
577 variant. If this is a type with a known alias set, return it. */
578 t
= TYPE_MAIN_VARIANT (t
);
579 if (TYPE_ALIAS_SET_KNOWN_P (t
))
580 return TYPE_ALIAS_SET (t
);
582 /* See if the language has special handling for this type. */
583 if ((set
= lang_get_alias_set (t
)) != -1)
586 /* There are no objects of FUNCTION_TYPE, so there's no point in
587 using up an alias set for them. (There are, of course, pointers
588 and references to functions, but that's different.) */
589 else if (TREE_CODE (t
) == FUNCTION_TYPE
)
592 /* Otherwise make a new alias set for this type. */
593 set
= new_alias_set ();
595 TYPE_ALIAS_SET (t
) = set
;
597 /* If this is an aggregate type, we must record any component aliasing
599 if (AGGREGATE_TYPE_P (t
) || TREE_CODE (t
) == COMPLEX_TYPE
)
600 record_component_aliases (t
);
605 /* Return a brand-new alias set. */
610 static HOST_WIDE_INT last_alias_set
;
612 if (flag_strict_aliasing
)
613 return ++last_alias_set
;
618 /* Indicate that things in SUBSET can alias things in SUPERSET, but
619 not vice versa. For example, in C, a store to an `int' can alias a
620 structure containing an `int', but not vice versa. Here, the
621 structure would be the SUPERSET and `int' the SUBSET. This
622 function should be called only once per SUPERSET/SUBSET pair.
624 It is illegal for SUPERSET to be zero; everything is implicitly a
625 subset of alias set zero. */
628 record_alias_subset (superset
, subset
)
629 HOST_WIDE_INT superset
;
630 HOST_WIDE_INT subset
;
632 alias_set_entry superset_entry
;
633 alias_set_entry subset_entry
;
635 /* It is possible in complex type situations for both sets to be the same,
636 in which case we can ignore this operation. */
637 if (superset
== subset
)
643 superset_entry
= get_alias_set_entry (superset
);
644 if (superset_entry
== 0)
646 /* Create an entry for the SUPERSET, so that we have a place to
647 attach the SUBSET. */
649 = (alias_set_entry
) xmalloc (sizeof (struct alias_set_entry
));
650 superset_entry
->alias_set
= superset
;
651 superset_entry
->children
652 = splay_tree_new (splay_tree_compare_ints
, 0, 0);
653 superset_entry
->has_zero_child
= 0;
654 splay_tree_insert (alias_sets
, (splay_tree_key
) superset
,
655 (splay_tree_value
) superset_entry
);
659 superset_entry
->has_zero_child
= 1;
662 subset_entry
= get_alias_set_entry (subset
);
663 /* If there is an entry for the subset, enter all of its children
664 (if they are not already present) as children of the SUPERSET. */
667 if (subset_entry
->has_zero_child
)
668 superset_entry
->has_zero_child
= 1;
670 splay_tree_foreach (subset_entry
->children
, insert_subset_children
,
671 superset_entry
->children
);
674 /* Enter the SUBSET itself as a child of the SUPERSET. */
675 splay_tree_insert (superset_entry
->children
,
676 (splay_tree_key
) subset
, 0);
680 /* Record that component types of TYPE, if any, are part of that type for
681 aliasing purposes. For record types, we only record component types
682 for fields that are marked addressable. For array types, we always
683 record the component types, so the front end should not call this
684 function if the individual component aren't addressable. */
687 record_component_aliases (type
)
690 HOST_WIDE_INT superset
= get_alias_set (type
);
696 switch (TREE_CODE (type
))
699 if (! TYPE_NONALIASED_COMPONENT (type
))
700 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
705 case QUAL_UNION_TYPE
:
706 for (field
= TYPE_FIELDS (type
); field
!= 0; field
= TREE_CHAIN (field
))
707 if (TREE_CODE (field
) == FIELD_DECL
&& ! DECL_NONADDRESSABLE_P (field
))
708 record_alias_subset (superset
, get_alias_set (TREE_TYPE (field
)));
712 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
720 /* Allocate an alias set for use in storing and reading from the varargs
724 get_varargs_alias_set ()
726 static HOST_WIDE_INT set
= -1;
729 set
= new_alias_set ();
734 /* Likewise, but used for the fixed portions of the frame, e.g., register
738 get_frame_alias_set ()
740 static HOST_WIDE_INT set
= -1;
743 set
= new_alias_set ();
748 /* Inside SRC, the source of a SET, find a base address. */
751 find_base_value (src
)
755 switch (GET_CODE (src
))
763 /* At the start of a function, argument registers have known base
764 values which may be lost later. Returning an ADDRESS
765 expression here allows optimization based on argument values
766 even when the argument registers are used for other purposes. */
767 if (regno
< FIRST_PSEUDO_REGISTER
&& copying_arguments
)
768 return new_reg_base_value
[regno
];
770 /* If a pseudo has a known base value, return it. Do not do this
771 for hard regs since it can result in a circular dependency
772 chain for registers which have values at function entry.
774 The test above is not sufficient because the scheduler may move
775 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
776 if (regno
>= FIRST_PSEUDO_REGISTER
777 && regno
< reg_base_value_size
778 && reg_base_value
[regno
])
779 return reg_base_value
[regno
];
784 /* Check for an argument passed in memory. Only record in the
785 copying-arguments block; it is too hard to track changes
787 if (copying_arguments
788 && (XEXP (src
, 0) == arg_pointer_rtx
789 || (GET_CODE (XEXP (src
, 0)) == PLUS
790 && XEXP (XEXP (src
, 0), 0) == arg_pointer_rtx
)))
791 return gen_rtx_ADDRESS (VOIDmode
, src
);
796 if (GET_CODE (src
) != PLUS
&& GET_CODE (src
) != MINUS
)
799 /* ... fall through ... */
804 rtx temp
, src_0
= XEXP (src
, 0), src_1
= XEXP (src
, 1);
806 /* If either operand is a REG, then see if we already have
807 a known value for it. */
808 if (GET_CODE (src_0
) == REG
)
810 temp
= find_base_value (src_0
);
815 if (GET_CODE (src_1
) == REG
)
817 temp
= find_base_value (src_1
);
822 /* Guess which operand is the base address:
823 If either operand is a symbol, then it is the base. If
824 either operand is a CONST_INT, then the other is the base. */
825 if (GET_CODE (src_1
) == CONST_INT
|| CONSTANT_P (src_0
))
826 return find_base_value (src_0
);
827 else if (GET_CODE (src_0
) == CONST_INT
|| CONSTANT_P (src_1
))
828 return find_base_value (src_1
);
830 /* This might not be necessary anymore:
831 If either operand is a REG that is a known pointer, then it
833 else if (GET_CODE (src_0
) == REG
&& REG_POINTER (src_0
))
834 return find_base_value (src_0
);
835 else if (GET_CODE (src_1
) == REG
&& REG_POINTER (src_1
))
836 return find_base_value (src_1
);
842 /* The standard form is (lo_sum reg sym) so look only at the
844 return find_base_value (XEXP (src
, 1));
847 /* If the second operand is constant set the base
848 address to the first operand. */
849 if (GET_CODE (XEXP (src
, 1)) == CONST_INT
&& INTVAL (XEXP (src
, 1)) != 0)
850 return find_base_value (XEXP (src
, 0));
854 if (GET_MODE_SIZE (GET_MODE (src
)) < GET_MODE_SIZE (Pmode
))
858 case SIGN_EXTEND
: /* used for NT/Alpha pointers */
860 return find_base_value (XEXP (src
, 0));
869 /* Called from init_alias_analysis indirectly through note_stores. */
871 /* While scanning insns to find base values, reg_seen[N] is nonzero if
872 register N has been set in this function. */
873 static char *reg_seen
;
875 /* Addresses which are known not to alias anything else are identified
876 by a unique integer. */
877 static int unique_id
;
880 record_set (dest
, set
, data
)
882 void *data ATTRIBUTE_UNUSED
;
887 if (GET_CODE (dest
) != REG
)
890 regno
= REGNO (dest
);
892 if (regno
>= reg_base_value_size
)
897 /* A CLOBBER wipes out any old value but does not prevent a previously
898 unset register from acquiring a base address (i.e. reg_seen is not
900 if (GET_CODE (set
) == CLOBBER
)
902 new_reg_base_value
[regno
] = 0;
911 new_reg_base_value
[regno
] = 0;
915 new_reg_base_value
[regno
] = gen_rtx_ADDRESS (Pmode
,
916 GEN_INT (unique_id
++));
920 /* This is not the first set. If the new value is not related to the
921 old value, forget the base value. Note that the following code is
923 extern int x, y; int *p = &x; p += (&y-&x);
924 ANSI C does not allow computing the difference of addresses
925 of distinct top level objects. */
926 if (new_reg_base_value
[regno
])
927 switch (GET_CODE (src
))
931 if (XEXP (src
, 0) != dest
&& XEXP (src
, 1) != dest
)
932 new_reg_base_value
[regno
] = 0;
935 /* If the value we add in the PLUS is also a valid base value,
936 this might be the actual base value, and the original value
939 rtx other
= NULL_RTX
;
941 if (XEXP (src
, 0) == dest
)
942 other
= XEXP (src
, 1);
943 else if (XEXP (src
, 1) == dest
)
944 other
= XEXP (src
, 0);
946 if (! other
|| find_base_value (other
))
947 new_reg_base_value
[regno
] = 0;
951 if (XEXP (src
, 0) != dest
|| GET_CODE (XEXP (src
, 1)) != CONST_INT
)
952 new_reg_base_value
[regno
] = 0;
955 new_reg_base_value
[regno
] = 0;
958 /* If this is the first set of a register, record the value. */
959 else if ((regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
960 && ! reg_seen
[regno
] && new_reg_base_value
[regno
] == 0)
961 new_reg_base_value
[regno
] = find_base_value (src
);
966 /* Called from loop optimization when a new pseudo-register is
967 created. It indicates that REGNO is being set to VAL. f INVARIANT
968 is true then this value also describes an invariant relationship
969 which can be used to deduce that two registers with unknown values
973 record_base_value (regno
, val
, invariant
)
978 if (regno
>= reg_base_value_size
)
981 if (invariant
&& alias_invariant
)
982 alias_invariant
[regno
] = val
;
984 if (GET_CODE (val
) == REG
)
986 if (REGNO (val
) < reg_base_value_size
)
987 reg_base_value
[regno
] = reg_base_value
[REGNO (val
)];
992 reg_base_value
[regno
] = find_base_value (val
);
995 /* Clear alias info for a register. This is used if an RTL transformation
996 changes the value of a register. This is used in flow by AUTO_INC_DEC
997 optimizations. We don't need to clear reg_base_value, since flow only
998 changes the offset. */
1001 clear_reg_alias_info (reg
)
1004 unsigned int regno
= REGNO (reg
);
1006 if (regno
< reg_known_value_size
&& regno
>= FIRST_PSEUDO_REGISTER
)
1007 reg_known_value
[regno
] = reg
;
1010 /* Returns a canonical version of X, from the point of view alias
1011 analysis. (For example, if X is a MEM whose address is a register,
1012 and the register has a known value (say a SYMBOL_REF), then a MEM
1013 whose address is the SYMBOL_REF is returned.) */
1019 /* Recursively look for equivalences. */
1020 if (GET_CODE (x
) == REG
&& REGNO (x
) >= FIRST_PSEUDO_REGISTER
1021 && REGNO (x
) < reg_known_value_size
)
1022 return reg_known_value
[REGNO (x
)] == x
1023 ? x
: canon_rtx (reg_known_value
[REGNO (x
)]);
1024 else if (GET_CODE (x
) == PLUS
)
1026 rtx x0
= canon_rtx (XEXP (x
, 0));
1027 rtx x1
= canon_rtx (XEXP (x
, 1));
1029 if (x0
!= XEXP (x
, 0) || x1
!= XEXP (x
, 1))
1031 if (GET_CODE (x0
) == CONST_INT
)
1032 return plus_constant (x1
, INTVAL (x0
));
1033 else if (GET_CODE (x1
) == CONST_INT
)
1034 return plus_constant (x0
, INTVAL (x1
));
1035 return gen_rtx_PLUS (GET_MODE (x
), x0
, x1
);
1039 /* This gives us much better alias analysis when called from
1040 the loop optimizer. Note we want to leave the original
1041 MEM alone, but need to return the canonicalized MEM with
1042 all the flags with their original values. */
1043 else if (GET_CODE (x
) == MEM
)
1044 x
= replace_equiv_address_nv (x
, canon_rtx (XEXP (x
, 0)));
1049 /* Return 1 if X and Y are identical-looking rtx's.
1051 We use the data in reg_known_value above to see if two registers with
1052 different numbers are, in fact, equivalent. */
1055 rtx_equal_for_memref_p (x
, y
)
1063 if (x
== 0 && y
== 0)
1065 if (x
== 0 || y
== 0)
1074 code
= GET_CODE (x
);
1075 /* Rtx's of different codes cannot be equal. */
1076 if (code
!= GET_CODE (y
))
1079 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1080 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1082 if (GET_MODE (x
) != GET_MODE (y
))
1085 /* Some RTL can be compared without a recursive examination. */
1089 return CSELIB_VAL_PTR (x
) == CSELIB_VAL_PTR (y
);
1092 return REGNO (x
) == REGNO (y
);
1095 return XEXP (x
, 0) == XEXP (y
, 0);
1098 return XSTR (x
, 0) == XSTR (y
, 0);
1102 /* There's no need to compare the contents of CONST_DOUBLEs or
1103 CONST_INTs because pointer equality is a good enough
1104 comparison for these nodes. */
1108 return (XINT (x
, 1) == XINT (y
, 1)
1109 && rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0)));
1115 /* For commutative operations, the RTX match if the operand match in any
1116 order. Also handle the simple binary and unary cases without a loop. */
1117 if (code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
1118 return ((rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0))
1119 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 1)))
1120 || (rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 1))
1121 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 0))));
1122 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
1123 return (rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0))
1124 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 1)));
1125 else if (GET_RTX_CLASS (code
) == '1')
1126 return rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0));
1128 /* Compare the elements. If any pair of corresponding elements
1129 fail to match, return 0 for the whole things.
1131 Limit cases to types which actually appear in addresses. */
1133 fmt
= GET_RTX_FORMAT (code
);
1134 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1139 if (XINT (x
, i
) != XINT (y
, i
))
1144 /* Two vectors must have the same length. */
1145 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1148 /* And the corresponding elements must match. */
1149 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1150 if (rtx_equal_for_memref_p (XVECEXP (x
, i
, j
),
1151 XVECEXP (y
, i
, j
)) == 0)
1156 if (rtx_equal_for_memref_p (XEXP (x
, i
), XEXP (y
, i
)) == 0)
1160 /* This can happen for asm operands. */
1162 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1166 /* This can happen for an asm which clobbers memory. */
1170 /* It is believed that rtx's at this level will never
1171 contain anything but integers and other rtx's,
1172 except for within LABEL_REFs and SYMBOL_REFs. */
1180 /* Given an rtx X, find a SYMBOL_REF or LABEL_REF within
1181 X and return it, or return 0 if none found. */
1184 find_symbolic_term (x
)
1191 code
= GET_CODE (x
);
1192 if (code
== SYMBOL_REF
|| code
== LABEL_REF
)
1194 if (GET_RTX_CLASS (code
) == 'o')
1197 fmt
= GET_RTX_FORMAT (code
);
1198 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1204 t
= find_symbolic_term (XEXP (x
, i
));
1208 else if (fmt
[i
] == 'E')
1219 struct elt_loc_list
*l
;
1221 #if defined (FIND_BASE_TERM)
1222 /* Try machine-dependent ways to find the base term. */
1223 x
= FIND_BASE_TERM (x
);
1226 switch (GET_CODE (x
))
1229 return REG_BASE_VALUE (x
);
1232 case SIGN_EXTEND
: /* Used for Alpha/NT pointers */
1238 return find_base_term (XEXP (x
, 0));
1241 val
= CSELIB_VAL_PTR (x
);
1242 for (l
= val
->locs
; l
; l
= l
->next
)
1243 if ((x
= find_base_term (l
->loc
)) != 0)
1249 if (GET_CODE (x
) != PLUS
&& GET_CODE (x
) != MINUS
)
1256 rtx tmp1
= XEXP (x
, 0);
1257 rtx tmp2
= XEXP (x
, 1);
1259 /* This is a litle bit tricky since we have to determine which of
1260 the two operands represents the real base address. Otherwise this
1261 routine may return the index register instead of the base register.
1263 That may cause us to believe no aliasing was possible, when in
1264 fact aliasing is possible.
1266 We use a few simple tests to guess the base register. Additional
1267 tests can certainly be added. For example, if one of the operands
1268 is a shift or multiply, then it must be the index register and the
1269 other operand is the base register. */
1271 if (tmp1
== pic_offset_table_rtx
&& CONSTANT_P (tmp2
))
1272 return find_base_term (tmp2
);
1274 /* If either operand is known to be a pointer, then use it
1275 to determine the base term. */
1276 if (REG_P (tmp1
) && REG_POINTER (tmp1
))
1277 return find_base_term (tmp1
);
1279 if (REG_P (tmp2
) && REG_POINTER (tmp2
))
1280 return find_base_term (tmp2
);
1282 /* Neither operand was known to be a pointer. Go ahead and find the
1283 base term for both operands. */
1284 tmp1
= find_base_term (tmp1
);
1285 tmp2
= find_base_term (tmp2
);
1287 /* If either base term is named object or a special address
1288 (like an argument or stack reference), then use it for the
1291 && (GET_CODE (tmp1
) == SYMBOL_REF
1292 || GET_CODE (tmp1
) == LABEL_REF
1293 || (GET_CODE (tmp1
) == ADDRESS
1294 && GET_MODE (tmp1
) != VOIDmode
)))
1298 && (GET_CODE (tmp2
) == SYMBOL_REF
1299 || GET_CODE (tmp2
) == LABEL_REF
1300 || (GET_CODE (tmp2
) == ADDRESS
1301 && GET_MODE (tmp2
) != VOIDmode
)))
1304 /* We could not determine which of the two operands was the
1305 base register and which was the index. So we can determine
1306 nothing from the base alias check. */
1311 if (GET_CODE (XEXP (x
, 0)) == REG
&& GET_CODE (XEXP (x
, 1)) == CONST_INT
)
1312 return REG_BASE_VALUE (XEXP (x
, 0));
1320 return REG_BASE_VALUE (frame_pointer_rtx
);
1327 /* Return 0 if the addresses X and Y are known to point to different
1328 objects, 1 if they might be pointers to the same object. */
1331 base_alias_check (x
, y
, x_mode
, y_mode
)
1333 enum machine_mode x_mode
, y_mode
;
1335 rtx x_base
= find_base_term (x
);
1336 rtx y_base
= find_base_term (y
);
1338 /* If the address itself has no known base see if a known equivalent
1339 value has one. If either address still has no known base, nothing
1340 is known about aliasing. */
1345 if (! flag_expensive_optimizations
|| (x_c
= canon_rtx (x
)) == x
)
1348 x_base
= find_base_term (x_c
);
1356 if (! flag_expensive_optimizations
|| (y_c
= canon_rtx (y
)) == y
)
1359 y_base
= find_base_term (y_c
);
1364 /* If the base addresses are equal nothing is known about aliasing. */
1365 if (rtx_equal_p (x_base
, y_base
))
1368 /* The base addresses of the read and write are different expressions.
1369 If they are both symbols and they are not accessed via AND, there is
1370 no conflict. We can bring knowledge of object alignment into play
1371 here. For example, on alpha, "char a, b;" can alias one another,
1372 though "char a; long b;" cannot. */
1373 if (GET_CODE (x_base
) != ADDRESS
&& GET_CODE (y_base
) != ADDRESS
)
1375 if (GET_CODE (x
) == AND
&& GET_CODE (y
) == AND
)
1377 if (GET_CODE (x
) == AND
1378 && (GET_CODE (XEXP (x
, 1)) != CONST_INT
1379 || (int) GET_MODE_UNIT_SIZE (y_mode
) < -INTVAL (XEXP (x
, 1))))
1381 if (GET_CODE (y
) == AND
1382 && (GET_CODE (XEXP (y
, 1)) != CONST_INT
1383 || (int) GET_MODE_UNIT_SIZE (x_mode
) < -INTVAL (XEXP (y
, 1))))
1385 /* Differing symbols never alias. */
1389 /* If one address is a stack reference there can be no alias:
1390 stack references using different base registers do not alias,
1391 a stack reference can not alias a parameter, and a stack reference
1392 can not alias a global. */
1393 if ((GET_CODE (x_base
) == ADDRESS
&& GET_MODE (x_base
) == Pmode
)
1394 || (GET_CODE (y_base
) == ADDRESS
&& GET_MODE (y_base
) == Pmode
))
1397 if (! flag_argument_noalias
)
1400 if (flag_argument_noalias
> 1)
1403 /* Weak noalias assertion (arguments are distinct, but may match globals). */
1404 return ! (GET_MODE (x_base
) == VOIDmode
&& GET_MODE (y_base
) == VOIDmode
);
1407 /* Convert the address X into something we can use. This is done by returning
1408 it unchanged unless it is a value; in the latter case we call cselib to get
1409 a more useful rtx. */
1416 struct elt_loc_list
*l
;
1418 if (GET_CODE (x
) != VALUE
)
1420 v
= CSELIB_VAL_PTR (x
);
1421 for (l
= v
->locs
; l
; l
= l
->next
)
1422 if (CONSTANT_P (l
->loc
))
1424 for (l
= v
->locs
; l
; l
= l
->next
)
1425 if (GET_CODE (l
->loc
) != REG
&& GET_CODE (l
->loc
) != MEM
)
1428 return v
->locs
->loc
;
1432 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
1433 where SIZE is the size in bytes of the memory reference. If ADDR
1434 is not modified by the memory reference then ADDR is returned. */
1437 addr_side_effect_eval (addr
, size
, n_refs
)
1444 switch (GET_CODE (addr
))
1447 offset
= (n_refs
+ 1) * size
;
1450 offset
= -(n_refs
+ 1) * size
;
1453 offset
= n_refs
* size
;
1456 offset
= -n_refs
* size
;
1464 addr
= gen_rtx_PLUS (GET_MODE (addr
), XEXP (addr
, 0), GEN_INT (offset
));
1466 addr
= XEXP (addr
, 0);
1471 /* Return nonzero if X and Y (memory addresses) could reference the
1472 same location in memory. C is an offset accumulator. When
1473 C is nonzero, we are testing aliases between X and Y + C.
1474 XSIZE is the size in bytes of the X reference,
1475 similarly YSIZE is the size in bytes for Y.
1477 If XSIZE or YSIZE is zero, we do not know the amount of memory being
1478 referenced (the reference was BLKmode), so make the most pessimistic
1481 If XSIZE or YSIZE is negative, we may access memory outside the object
1482 being referenced as a side effect. This can happen when using AND to
1483 align memory references, as is done on the Alpha.
1485 Nice to notice that varying addresses cannot conflict with fp if no
1486 local variables had their addresses taken, but that's too hard now. */
1489 memrefs_conflict_p (xsize
, x
, ysize
, y
, c
)
1494 if (GET_CODE (x
) == VALUE
)
1496 if (GET_CODE (y
) == VALUE
)
1498 if (GET_CODE (x
) == HIGH
)
1500 else if (GET_CODE (x
) == LO_SUM
)
1503 x
= canon_rtx (addr_side_effect_eval (x
, xsize
, 0));
1504 if (GET_CODE (y
) == HIGH
)
1506 else if (GET_CODE (y
) == LO_SUM
)
1509 y
= canon_rtx (addr_side_effect_eval (y
, ysize
, 0));
1511 if (rtx_equal_for_memref_p (x
, y
))
1513 if (xsize
<= 0 || ysize
<= 0)
1515 if (c
>= 0 && xsize
> c
)
1517 if (c
< 0 && ysize
+c
> 0)
1522 /* This code used to check for conflicts involving stack references and
1523 globals but the base address alias code now handles these cases. */
1525 if (GET_CODE (x
) == PLUS
)
1527 /* The fact that X is canonicalized means that this
1528 PLUS rtx is canonicalized. */
1529 rtx x0
= XEXP (x
, 0);
1530 rtx x1
= XEXP (x
, 1);
1532 if (GET_CODE (y
) == PLUS
)
1534 /* The fact that Y is canonicalized means that this
1535 PLUS rtx is canonicalized. */
1536 rtx y0
= XEXP (y
, 0);
1537 rtx y1
= XEXP (y
, 1);
1539 if (rtx_equal_for_memref_p (x1
, y1
))
1540 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
1541 if (rtx_equal_for_memref_p (x0
, y0
))
1542 return memrefs_conflict_p (xsize
, x1
, ysize
, y1
, c
);
1543 if (GET_CODE (x1
) == CONST_INT
)
1545 if (GET_CODE (y1
) == CONST_INT
)
1546 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
,
1547 c
- INTVAL (x1
) + INTVAL (y1
));
1549 return memrefs_conflict_p (xsize
, x0
, ysize
, y
,
1552 else if (GET_CODE (y1
) == CONST_INT
)
1553 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
1557 else if (GET_CODE (x1
) == CONST_INT
)
1558 return memrefs_conflict_p (xsize
, x0
, ysize
, y
, c
- INTVAL (x1
));
1560 else if (GET_CODE (y
) == PLUS
)
1562 /* The fact that Y is canonicalized means that this
1563 PLUS rtx is canonicalized. */
1564 rtx y0
= XEXP (y
, 0);
1565 rtx y1
= XEXP (y
, 1);
1567 if (GET_CODE (y1
) == CONST_INT
)
1568 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
1573 if (GET_CODE (x
) == GET_CODE (y
))
1574 switch (GET_CODE (x
))
1578 /* Handle cases where we expect the second operands to be the
1579 same, and check only whether the first operand would conflict
1582 rtx x1
= canon_rtx (XEXP (x
, 1));
1583 rtx y1
= canon_rtx (XEXP (y
, 1));
1584 if (! rtx_equal_for_memref_p (x1
, y1
))
1586 x0
= canon_rtx (XEXP (x
, 0));
1587 y0
= canon_rtx (XEXP (y
, 0));
1588 if (rtx_equal_for_memref_p (x0
, y0
))
1589 return (xsize
== 0 || ysize
== 0
1590 || (c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0));
1592 /* Can't properly adjust our sizes. */
1593 if (GET_CODE (x1
) != CONST_INT
)
1595 xsize
/= INTVAL (x1
);
1596 ysize
/= INTVAL (x1
);
1598 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
1602 /* Are these registers known not to be equal? */
1603 if (alias_invariant
)
1605 unsigned int r_x
= REGNO (x
), r_y
= REGNO (y
);
1606 rtx i_x
, i_y
; /* invariant relationships of X and Y */
1608 i_x
= r_x
>= reg_base_value_size
? 0 : alias_invariant
[r_x
];
1609 i_y
= r_y
>= reg_base_value_size
? 0 : alias_invariant
[r_y
];
1611 if (i_x
== 0 && i_y
== 0)
1614 if (! memrefs_conflict_p (xsize
, i_x
? i_x
: x
,
1615 ysize
, i_y
? i_y
: y
, c
))
1624 /* Treat an access through an AND (e.g. a subword access on an Alpha)
1625 as an access with indeterminate size. Assume that references
1626 besides AND are aligned, so if the size of the other reference is
1627 at least as large as the alignment, assume no other overlap. */
1628 if (GET_CODE (x
) == AND
&& GET_CODE (XEXP (x
, 1)) == CONST_INT
)
1630 if (GET_CODE (y
) == AND
|| ysize
< -INTVAL (XEXP (x
, 1)))
1632 return memrefs_conflict_p (xsize
, XEXP (x
, 0), ysize
, y
, c
);
1634 if (GET_CODE (y
) == AND
&& GET_CODE (XEXP (y
, 1)) == CONST_INT
)
1636 /* ??? If we are indexing far enough into the array/structure, we
1637 may yet be able to determine that we can not overlap. But we
1638 also need to that we are far enough from the end not to overlap
1639 a following reference, so we do nothing with that for now. */
1640 if (GET_CODE (x
) == AND
|| xsize
< -INTVAL (XEXP (y
, 1)))
1642 return memrefs_conflict_p (xsize
, x
, ysize
, XEXP (y
, 0), c
);
1645 if (GET_CODE (x
) == ADDRESSOF
)
1647 if (y
== frame_pointer_rtx
1648 || GET_CODE (y
) == ADDRESSOF
)
1649 return xsize
<= 0 || ysize
<= 0;
1651 if (GET_CODE (y
) == ADDRESSOF
)
1653 if (x
== frame_pointer_rtx
)
1654 return xsize
<= 0 || ysize
<= 0;
1659 if (GET_CODE (x
) == CONST_INT
&& GET_CODE (y
) == CONST_INT
)
1661 c
+= (INTVAL (y
) - INTVAL (x
));
1662 return (xsize
<= 0 || ysize
<= 0
1663 || (c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0));
1666 if (GET_CODE (x
) == CONST
)
1668 if (GET_CODE (y
) == CONST
)
1669 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
1670 ysize
, canon_rtx (XEXP (y
, 0)), c
);
1672 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
1675 if (GET_CODE (y
) == CONST
)
1676 return memrefs_conflict_p (xsize
, x
, ysize
,
1677 canon_rtx (XEXP (y
, 0)), c
);
1680 return (xsize
<= 0 || ysize
<= 0
1681 || (rtx_equal_for_memref_p (x
, y
)
1682 && ((c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0))));
1689 /* Functions to compute memory dependencies.
1691 Since we process the insns in execution order, we can build tables
1692 to keep track of what registers are fixed (and not aliased), what registers
1693 are varying in known ways, and what registers are varying in unknown
1696 If both memory references are volatile, then there must always be a
1697 dependence between the two references, since their order can not be
1698 changed. A volatile and non-volatile reference can be interchanged
1701 A MEM_IN_STRUCT reference at a non-AND varying address can never
1702 conflict with a non-MEM_IN_STRUCT reference at a fixed address. We
1703 also must allow AND addresses, because they may generate accesses
1704 outside the object being referenced. This is used to generate
1705 aligned addresses from unaligned addresses, for instance, the alpha
1706 storeqi_unaligned pattern. */
1708 /* Read dependence: X is read after read in MEM takes place. There can
1709 only be a dependence here if both reads are volatile. */
1712 read_dependence (mem
, x
)
1716 return MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
);
1719 /* Returns MEM1 if and only if MEM1 is a scalar at a fixed address and
1720 MEM2 is a reference to a structure at a varying address, or returns
1721 MEM2 if vice versa. Otherwise, returns NULL_RTX. If a non-NULL
1722 value is returned MEM1 and MEM2 can never alias. VARIES_P is used
1723 to decide whether or not an address may vary; it should return
1724 nonzero whenever variation is possible.
1725 MEM1_ADDR and MEM2_ADDR are the addresses of MEM1 and MEM2. */
1728 fixed_scalar_and_varying_struct_p (mem1
, mem2
, mem1_addr
, mem2_addr
, varies_p
)
1730 rtx mem1_addr
, mem2_addr
;
1731 int (*varies_p
) PARAMS ((rtx
, int));
1733 if (! flag_strict_aliasing
)
1736 if (MEM_SCALAR_P (mem1
) && MEM_IN_STRUCT_P (mem2
)
1737 && !varies_p (mem1_addr
, 1) && varies_p (mem2_addr
, 1))
1738 /* MEM1 is a scalar at a fixed address; MEM2 is a struct at a
1742 if (MEM_IN_STRUCT_P (mem1
) && MEM_SCALAR_P (mem2
)
1743 && varies_p (mem1_addr
, 1) && !varies_p (mem2_addr
, 1))
1744 /* MEM2 is a scalar at a fixed address; MEM1 is a struct at a
1751 /* Returns nonzero if something about the mode or address format MEM1
1752 indicates that it might well alias *anything*. */
1755 aliases_everything_p (mem
)
1758 if (GET_CODE (XEXP (mem
, 0)) == AND
)
1759 /* If the address is an AND, its very hard to know at what it is
1760 actually pointing. */
1766 /* True dependence: X is read after store in MEM takes place. */
1769 true_dependence (mem
, mem_mode
, x
, varies
)
1771 enum machine_mode mem_mode
;
1773 int (*varies
) PARAMS ((rtx
, int));
1775 rtx x_addr
, mem_addr
;
1778 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
1781 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
1784 /* Unchanging memory can't conflict with non-unchanging memory.
1785 A non-unchanging read can conflict with a non-unchanging write.
1786 An unchanging read can conflict with an unchanging write since
1787 there may be a single store to this address to initialize it.
1788 Note that an unchanging store can conflict with a non-unchanging read
1789 since we have to make conservative assumptions when we have a
1790 record with readonly fields and we are copying the whole thing.
1791 Just fall through to the code below to resolve potential conflicts.
1792 This won't handle all cases optimally, but the possible performance
1793 loss should be negligible. */
1794 if (RTX_UNCHANGING_P (x
) && ! RTX_UNCHANGING_P (mem
))
1797 if (mem_mode
== VOIDmode
)
1798 mem_mode
= GET_MODE (mem
);
1800 x_addr
= get_addr (XEXP (x
, 0));
1801 mem_addr
= get_addr (XEXP (mem
, 0));
1803 base
= find_base_term (x_addr
);
1804 if (base
&& (GET_CODE (base
) == LABEL_REF
1805 || (GET_CODE (base
) == SYMBOL_REF
1806 && CONSTANT_POOL_ADDRESS_P (base
))))
1809 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
), mem_mode
))
1812 x_addr
= canon_rtx (x_addr
);
1813 mem_addr
= canon_rtx (mem_addr
);
1815 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
1816 SIZE_FOR_MODE (x
), x_addr
, 0))
1819 if (aliases_everything_p (x
))
1822 /* We cannot use aliases_everyting_p to test MEM, since we must look
1823 at MEM_MODE, rather than GET_MODE (MEM). */
1824 if (mem_mode
== QImode
|| GET_CODE (mem_addr
) == AND
)
1827 /* In true_dependence we also allow BLKmode to alias anything. Why
1828 don't we do this in anti_dependence and output_dependence? */
1829 if (mem_mode
== BLKmode
|| GET_MODE (x
) == BLKmode
)
1832 return ! fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
1836 /* Canonical true dependence: X is read after store in MEM takes place.
1837 Variant of true_dependece which assumes MEM has already been
1838 canonicalized (hence we no longer do that here).
1839 The mem_addr argument has been added, since true_dependence computed
1840 this value prior to canonicalizing. */
1843 canon_true_dependence (mem
, mem_mode
, mem_addr
, x
, varies
)
1844 rtx mem
, mem_addr
, x
;
1845 enum machine_mode mem_mode
;
1846 int (*varies
) PARAMS ((rtx
, int));
1850 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
1853 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
1856 /* If X is an unchanging read, then it can't possibly conflict with any
1857 non-unchanging store. It may conflict with an unchanging write though,
1858 because there may be a single store to this address to initialize it.
1859 Just fall through to the code below to resolve the case where we have
1860 both an unchanging read and an unchanging write. This won't handle all
1861 cases optimally, but the possible performance loss should be
1863 if (RTX_UNCHANGING_P (x
) && ! RTX_UNCHANGING_P (mem
))
1866 x_addr
= get_addr (XEXP (x
, 0));
1868 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
), mem_mode
))
1871 x_addr
= canon_rtx (x_addr
);
1872 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
1873 SIZE_FOR_MODE (x
), x_addr
, 0))
1876 if (aliases_everything_p (x
))
1879 /* We cannot use aliases_everyting_p to test MEM, since we must look
1880 at MEM_MODE, rather than GET_MODE (MEM). */
1881 if (mem_mode
== QImode
|| GET_CODE (mem_addr
) == AND
)
1884 /* In true_dependence we also allow BLKmode to alias anything. Why
1885 don't we do this in anti_dependence and output_dependence? */
1886 if (mem_mode
== BLKmode
|| GET_MODE (x
) == BLKmode
)
1889 return ! fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
1893 /* Returns non-zero if a write to X might alias a previous read from
1894 (or, if WRITEP is non-zero, a write to) MEM. */
1897 write_dependence_p (mem
, x
, writep
)
1902 rtx x_addr
, mem_addr
;
1906 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
1909 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
1912 /* Unchanging memory can't conflict with non-unchanging memory. */
1913 if (RTX_UNCHANGING_P (x
) != RTX_UNCHANGING_P (mem
))
1916 /* If MEM is an unchanging read, then it can't possibly conflict with
1917 the store to X, because there is at most one store to MEM, and it must
1918 have occurred somewhere before MEM. */
1919 if (! writep
&& RTX_UNCHANGING_P (mem
))
1922 x_addr
= get_addr (XEXP (x
, 0));
1923 mem_addr
= get_addr (XEXP (mem
, 0));
1927 base
= find_base_term (mem_addr
);
1928 if (base
&& (GET_CODE (base
) == LABEL_REF
1929 || (GET_CODE (base
) == SYMBOL_REF
1930 && CONSTANT_POOL_ADDRESS_P (base
))))
1934 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
),
1938 x_addr
= canon_rtx (x_addr
);
1939 mem_addr
= canon_rtx (mem_addr
);
1941 if (!memrefs_conflict_p (SIZE_FOR_MODE (mem
), mem_addr
,
1942 SIZE_FOR_MODE (x
), x_addr
, 0))
1946 = fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
1949 return (!(fixed_scalar
== mem
&& !aliases_everything_p (x
))
1950 && !(fixed_scalar
== x
&& !aliases_everything_p (mem
)));
1953 /* Anti dependence: X is written after read in MEM takes place. */
1956 anti_dependence (mem
, x
)
1960 return write_dependence_p (mem
, x
, /*writep=*/0);
1963 /* Output dependence: X is written after store in MEM takes place. */
1966 output_dependence (mem
, x
)
1970 return write_dependence_p (mem
, x
, /*writep=*/1);
1973 /* Returns non-zero if X mentions something which is not
1974 local to the function and is not constant. */
1977 nonlocal_mentioned_p (x
)
1984 code
= GET_CODE (x
);
1986 if (GET_RTX_CLASS (code
) == 'i')
1988 /* Constant functions can be constant if they don't use
1989 scratch memory used to mark function w/o side effects. */
1990 if (code
== CALL_INSN
&& CONST_OR_PURE_CALL_P (x
))
1992 x
= CALL_INSN_FUNCTION_USAGE (x
);
1998 code
= GET_CODE (x
);
2004 if (GET_CODE (SUBREG_REG (x
)) == REG
)
2006 /* Global registers are not local. */
2007 if (REGNO (SUBREG_REG (x
)) < FIRST_PSEUDO_REGISTER
2008 && global_regs
[subreg_regno (x
)])
2016 /* Global registers are not local. */
2017 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2031 /* Constants in the function's constants pool are constant. */
2032 if (CONSTANT_POOL_ADDRESS_P (x
))
2037 /* Non-constant calls and recursion are not local. */
2041 /* Be overly conservative and consider any volatile memory
2042 reference as not local. */
2043 if (MEM_VOLATILE_P (x
))
2045 base
= find_base_term (XEXP (x
, 0));
2048 /* A Pmode ADDRESS could be a reference via the structure value
2049 address or static chain. Such memory references are nonlocal.
2051 Thus, we have to examine the contents of the ADDRESS to find
2052 out if this is a local reference or not. */
2053 if (GET_CODE (base
) == ADDRESS
2054 && GET_MODE (base
) == Pmode
2055 && (XEXP (base
, 0) == stack_pointer_rtx
2056 || XEXP (base
, 0) == arg_pointer_rtx
2057 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2058 || XEXP (base
, 0) == hard_frame_pointer_rtx
2060 || XEXP (base
, 0) == frame_pointer_rtx
))
2062 /* Constants in the function's constant pool are constant. */
2063 if (GET_CODE (base
) == SYMBOL_REF
&& CONSTANT_POOL_ADDRESS_P (base
))
2068 case UNSPEC_VOLATILE
:
2073 if (MEM_VOLATILE_P (x
))
2082 /* Recursively scan the operands of this expression. */
2085 const char *fmt
= GET_RTX_FORMAT (code
);
2088 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2090 if (fmt
[i
] == 'e' && XEXP (x
, i
))
2092 if (nonlocal_mentioned_p (XEXP (x
, i
)))
2095 else if (fmt
[i
] == 'E')
2098 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2099 if (nonlocal_mentioned_p (XVECEXP (x
, i
, j
)))
2108 /* Mark the function if it is constant. */
2111 mark_constant_function ()
2114 int nonlocal_mentioned
;
2116 if (TREE_PUBLIC (current_function_decl
)
2117 || TREE_READONLY (current_function_decl
)
2118 || DECL_IS_PURE (current_function_decl
)
2119 || TREE_THIS_VOLATILE (current_function_decl
)
2120 || TYPE_MODE (TREE_TYPE (current_function_decl
)) == VOIDmode
)
2123 /* A loop might not return which counts as a side effect. */
2124 if (mark_dfs_back_edges ())
2127 nonlocal_mentioned
= 0;
2129 init_alias_analysis ();
2131 /* Determine if this is a constant function. */
2133 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
2134 if (INSN_P (insn
) && nonlocal_mentioned_p (insn
))
2136 nonlocal_mentioned
= 1;
2140 end_alias_analysis ();
2142 /* Mark the function. */
2144 if (! nonlocal_mentioned
)
2145 TREE_READONLY (current_function_decl
) = 1;
2149 static HARD_REG_SET argument_registers
;
2156 #ifndef OUTGOING_REGNO
2157 #define OUTGOING_REGNO(N) N
2159 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2160 /* Check whether this register can hold an incoming pointer
2161 argument. FUNCTION_ARG_REGNO_P tests outgoing register
2162 numbers, so translate if necessary due to register windows. */
2163 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i
))
2164 && HARD_REGNO_MODE_OK (i
, Pmode
))
2165 SET_HARD_REG_BIT (argument_registers
, i
);
2167 alias_sets
= splay_tree_new (splay_tree_compare_ints
, 0, 0);
2170 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
2174 init_alias_analysis ()
2176 int maxreg
= max_reg_num ();
2182 reg_known_value_size
= maxreg
;
2185 = (rtx
*) xcalloc ((maxreg
- FIRST_PSEUDO_REGISTER
), sizeof (rtx
))
2186 - FIRST_PSEUDO_REGISTER
;
2188 = (char*) xcalloc ((maxreg
- FIRST_PSEUDO_REGISTER
), sizeof (char))
2189 - FIRST_PSEUDO_REGISTER
;
2191 /* Overallocate reg_base_value to allow some growth during loop
2192 optimization. Loop unrolling can create a large number of
2194 reg_base_value_size
= maxreg
* 2;
2195 reg_base_value
= (rtx
*) xcalloc (reg_base_value_size
, sizeof (rtx
));
2196 ggc_add_rtx_root (reg_base_value
, reg_base_value_size
);
2198 new_reg_base_value
= (rtx
*) xmalloc (reg_base_value_size
* sizeof (rtx
));
2199 reg_seen
= (char *) xmalloc (reg_base_value_size
);
2200 if (! reload_completed
&& flag_unroll_loops
)
2202 /* ??? Why are we realloc'ing if we're just going to zero it? */
2203 alias_invariant
= (rtx
*)xrealloc (alias_invariant
,
2204 reg_base_value_size
* sizeof (rtx
));
2205 memset ((char *)alias_invariant
, 0, reg_base_value_size
* sizeof (rtx
));
2208 /* The basic idea is that each pass through this loop will use the
2209 "constant" information from the previous pass to propagate alias
2210 information through another level of assignments.
2212 This could get expensive if the assignment chains are long. Maybe
2213 we should throttle the number of iterations, possibly based on
2214 the optimization level or flag_expensive_optimizations.
2216 We could propagate more information in the first pass by making use
2217 of REG_N_SETS to determine immediately that the alias information
2218 for a pseudo is "constant".
2220 A program with an uninitialized variable can cause an infinite loop
2221 here. Instead of doing a full dataflow analysis to detect such problems
2222 we just cap the number of iterations for the loop.
2224 The state of the arrays for the set chain in question does not matter
2225 since the program has undefined behavior. */
2230 /* Assume nothing will change this iteration of the loop. */
2233 /* We want to assign the same IDs each iteration of this loop, so
2234 start counting from zero each iteration of the loop. */
2237 /* We're at the start of the funtion each iteration through the
2238 loop, so we're copying arguments. */
2239 copying_arguments
= 1;
2241 /* Wipe the potential alias information clean for this pass. */
2242 memset ((char *) new_reg_base_value
, 0, reg_base_value_size
* sizeof (rtx
));
2244 /* Wipe the reg_seen array clean. */
2245 memset ((char *) reg_seen
, 0, reg_base_value_size
);
2247 /* Mark all hard registers which may contain an address.
2248 The stack, frame and argument pointers may contain an address.
2249 An argument register which can hold a Pmode value may contain
2250 an address even if it is not in BASE_REGS.
2252 The address expression is VOIDmode for an argument and
2253 Pmode for other registers. */
2255 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2256 if (TEST_HARD_REG_BIT (argument_registers
, i
))
2257 new_reg_base_value
[i
] = gen_rtx_ADDRESS (VOIDmode
,
2258 gen_rtx_REG (Pmode
, i
));
2260 new_reg_base_value
[STACK_POINTER_REGNUM
]
2261 = gen_rtx_ADDRESS (Pmode
, stack_pointer_rtx
);
2262 new_reg_base_value
[ARG_POINTER_REGNUM
]
2263 = gen_rtx_ADDRESS (Pmode
, arg_pointer_rtx
);
2264 new_reg_base_value
[FRAME_POINTER_REGNUM
]
2265 = gen_rtx_ADDRESS (Pmode
, frame_pointer_rtx
);
2266 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2267 new_reg_base_value
[HARD_FRAME_POINTER_REGNUM
]
2268 = gen_rtx_ADDRESS (Pmode
, hard_frame_pointer_rtx
);
2271 /* Walk the insns adding values to the new_reg_base_value array. */
2272 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
2278 #if defined (HAVE_prologue) || defined (HAVE_epilogue)
2279 /* The prologue/epilouge insns are not threaded onto the
2280 insn chain until after reload has completed. Thus,
2281 there is no sense wasting time checking if INSN is in
2282 the prologue/epilogue until after reload has completed. */
2283 if (reload_completed
2284 && prologue_epilogue_contains (insn
))
2288 /* If this insn has a noalias note, process it, Otherwise,
2289 scan for sets. A simple set will have no side effects
2290 which could change the base value of any other register. */
2292 if (GET_CODE (PATTERN (insn
)) == SET
2293 && REG_NOTES (insn
) != 0
2294 && find_reg_note (insn
, REG_NOALIAS
, NULL_RTX
))
2295 record_set (SET_DEST (PATTERN (insn
)), NULL_RTX
, NULL
);
2297 note_stores (PATTERN (insn
), record_set
, NULL
);
2299 set
= single_set (insn
);
2302 && GET_CODE (SET_DEST (set
)) == REG
2303 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
)
2305 unsigned int regno
= REGNO (SET_DEST (set
));
2306 rtx src
= SET_SRC (set
);
2308 if (REG_NOTES (insn
) != 0
2309 && (((note
= find_reg_note (insn
, REG_EQUAL
, 0)) != 0
2310 && REG_N_SETS (regno
) == 1)
2311 || (note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) != 0)
2312 && GET_CODE (XEXP (note
, 0)) != EXPR_LIST
2313 && ! rtx_varies_p (XEXP (note
, 0), 1)
2314 && ! reg_overlap_mentioned_p (SET_DEST (set
), XEXP (note
, 0)))
2316 reg_known_value
[regno
] = XEXP (note
, 0);
2317 reg_known_equiv_p
[regno
] = REG_NOTE_KIND (note
) == REG_EQUIV
;
2319 else if (REG_N_SETS (regno
) == 1
2320 && GET_CODE (src
) == PLUS
2321 && GET_CODE (XEXP (src
, 0)) == REG
2322 && REGNO (XEXP (src
, 0)) >= FIRST_PSEUDO_REGISTER
2323 && (reg_known_value
[REGNO (XEXP (src
, 0))])
2324 && GET_CODE (XEXP (src
, 1)) == CONST_INT
)
2326 rtx op0
= XEXP (src
, 0);
2327 op0
= reg_known_value
[REGNO (op0
)];
2328 reg_known_value
[regno
]
2329 = plus_constant (op0
, INTVAL (XEXP (src
, 1)));
2330 reg_known_equiv_p
[regno
] = 0;
2332 else if (REG_N_SETS (regno
) == 1
2333 && ! rtx_varies_p (src
, 1))
2335 reg_known_value
[regno
] = src
;
2336 reg_known_equiv_p
[regno
] = 0;
2340 else if (GET_CODE (insn
) == NOTE
2341 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_BEG
)
2342 copying_arguments
= 0;
2345 /* Now propagate values from new_reg_base_value to reg_base_value. */
2346 for (ui
= 0; ui
< reg_base_value_size
; ui
++)
2348 if (new_reg_base_value
[ui
]
2349 && new_reg_base_value
[ui
] != reg_base_value
[ui
]
2350 && ! rtx_equal_p (new_reg_base_value
[ui
], reg_base_value
[ui
]))
2352 reg_base_value
[ui
] = new_reg_base_value
[ui
];
2357 while (changed
&& ++pass
< MAX_ALIAS_LOOP_PASSES
);
2359 /* Fill in the remaining entries. */
2360 for (i
= FIRST_PSEUDO_REGISTER
; i
< maxreg
; i
++)
2361 if (reg_known_value
[i
] == 0)
2362 reg_known_value
[i
] = regno_reg_rtx
[i
];
2364 /* Simplify the reg_base_value array so that no register refers to
2365 another register, except to special registers indirectly through
2366 ADDRESS expressions.
2368 In theory this loop can take as long as O(registers^2), but unless
2369 there are very long dependency chains it will run in close to linear
2372 This loop may not be needed any longer now that the main loop does
2373 a better job at propagating alias information. */
2379 for (ui
= 0; ui
< reg_base_value_size
; ui
++)
2381 rtx base
= reg_base_value
[ui
];
2382 if (base
&& GET_CODE (base
) == REG
)
2384 unsigned int base_regno
= REGNO (base
);
2385 if (base_regno
== ui
) /* register set from itself */
2386 reg_base_value
[ui
] = 0;
2388 reg_base_value
[ui
] = reg_base_value
[base_regno
];
2393 while (changed
&& pass
< MAX_ALIAS_LOOP_PASSES
);
2396 free (new_reg_base_value
);
2397 new_reg_base_value
= 0;
2403 end_alias_analysis ()
2405 free (reg_known_value
+ FIRST_PSEUDO_REGISTER
);
2406 reg_known_value
= 0;
2407 reg_known_value_size
= 0;
2408 free (reg_known_equiv_p
+ FIRST_PSEUDO_REGISTER
);
2409 reg_known_equiv_p
= 0;
2412 ggc_del_root (reg_base_value
);
2413 free (reg_base_value
);
2416 reg_base_value_size
= 0;
2417 if (alias_invariant
)
2419 free (alias_invariant
);
2420 alias_invariant
= 0;