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 /* Static hunks of RTL used by the aliasing code; these are initialized
160 once per function to avoid unnecessary RTL allocations. */
161 static GTY (()) rtx static_reg_base_value
[FIRST_PSEUDO_REGISTER
];
163 #define REG_BASE_VALUE(X) \
164 (REGNO (X) < reg_base_value_size \
165 ? reg_base_value[REGNO (X)] : 0)
167 /* Vector of known invariant relationships between registers. Set in
168 loop unrolling. Indexed by register number, if nonzero the value
169 is an expression describing this register in terms of another.
171 The length of this array is REG_BASE_VALUE_SIZE.
173 Because this array contains only pseudo registers it has no effect
175 static rtx
*alias_invariant
;
177 /* Vector indexed by N giving the initial (unchanging) value known for
178 pseudo-register N. This array is initialized in
179 init_alias_analysis, and does not change until end_alias_analysis
181 rtx
*reg_known_value
;
183 /* Indicates number of valid entries in reg_known_value. */
184 static unsigned int reg_known_value_size
;
186 /* Vector recording for each reg_known_value whether it is due to a
187 REG_EQUIV note. Future passes (viz., reload) may replace the
188 pseudo with the equivalent expression and so we account for the
189 dependences that would be introduced if that happens.
191 The REG_EQUIV notes created in assign_parms may mention the arg
192 pointer, and there are explicit insns in the RTL that modify the
193 arg pointer. Thus we must ensure that such insns don't get
194 scheduled across each other because that would invalidate the
195 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
196 wrong, but solving the problem in the scheduler will likely give
197 better code, so we do it here. */
198 char *reg_known_equiv_p
;
200 /* True when scanning insns from the start of the rtl to the
201 NOTE_INSN_FUNCTION_BEG note. */
202 static int copying_arguments
;
204 /* The splay-tree used to store the various alias set entries. */
205 static splay_tree alias_sets
;
207 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
208 such an entry, or NULL otherwise. */
210 static alias_set_entry
211 get_alias_set_entry (alias_set
)
212 HOST_WIDE_INT alias_set
;
215 = splay_tree_lookup (alias_sets
, (splay_tree_key
) alias_set
);
217 return sn
!= 0 ? ((alias_set_entry
) sn
->value
) : 0;
220 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
221 the two MEMs cannot alias each other. */
224 mems_in_disjoint_alias_sets_p (mem1
, mem2
)
228 #ifdef ENABLE_CHECKING
229 /* Perform a basic sanity check. Namely, that there are no alias sets
230 if we're not using strict aliasing. This helps to catch bugs
231 whereby someone uses PUT_CODE, but doesn't clear MEM_ALIAS_SET, or
232 where a MEM is allocated in some way other than by the use of
233 gen_rtx_MEM, and the MEM_ALIAS_SET is not cleared. If we begin to
234 use alias sets to indicate that spilled registers cannot alias each
235 other, we might need to remove this check. */
236 if (! flag_strict_aliasing
237 && (MEM_ALIAS_SET (mem1
) != 0 || MEM_ALIAS_SET (mem2
) != 0))
241 return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1
), MEM_ALIAS_SET (mem2
));
244 /* Insert the NODE into the splay tree given by DATA. Used by
245 record_alias_subset via splay_tree_foreach. */
248 insert_subset_children (node
, data
)
249 splay_tree_node node
;
252 splay_tree_insert ((splay_tree
) data
, node
->key
, node
->value
);
257 /* Return 1 if the two specified alias sets may conflict. */
260 alias_sets_conflict_p (set1
, set2
)
261 HOST_WIDE_INT set1
, set2
;
265 /* If have no alias set information for one of the operands, we have
266 to assume it can alias anything. */
267 if (set1
== 0 || set2
== 0
268 /* If the two alias sets are the same, they may alias. */
272 /* See if the first alias set is a subset of the second. */
273 ase
= get_alias_set_entry (set1
);
275 && (ase
->has_zero_child
276 || splay_tree_lookup (ase
->children
,
277 (splay_tree_key
) set2
)))
280 /* Now do the same, but with the alias sets reversed. */
281 ase
= get_alias_set_entry (set2
);
283 && (ase
->has_zero_child
284 || splay_tree_lookup (ase
->children
,
285 (splay_tree_key
) set1
)))
288 /* The two alias sets are distinct and neither one is the
289 child of the other. Therefore, they cannot alias. */
293 /* Return 1 if TYPE is a RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE and has
294 has any readonly fields. If any of the fields have types that
295 contain readonly fields, return true as well. */
298 readonly_fields_p (type
)
303 if (TREE_CODE (type
) != RECORD_TYPE
&& TREE_CODE (type
) != UNION_TYPE
304 && TREE_CODE (type
) != QUAL_UNION_TYPE
)
307 for (field
= TYPE_FIELDS (type
); field
!= 0; field
= TREE_CHAIN (field
))
308 if (TREE_CODE (field
) == FIELD_DECL
309 && (TREE_READONLY (field
)
310 || readonly_fields_p (TREE_TYPE (field
))))
316 /* Return 1 if any MEM object of type T1 will always conflict (using the
317 dependency routines in this file) with any MEM object of type T2.
318 This is used when allocating temporary storage. If T1 and/or T2 are
319 NULL_TREE, it means we know nothing about the storage. */
322 objects_must_conflict_p (t1
, t2
)
325 /* If neither has a type specified, we don't know if they'll conflict
326 because we may be using them to store objects of various types, for
327 example the argument and local variables areas of inlined functions. */
328 if (t1
== 0 && t2
== 0)
331 /* If one or the other has readonly fields or is readonly,
332 then they may not conflict. */
333 if ((t1
!= 0 && readonly_fields_p (t1
))
334 || (t2
!= 0 && readonly_fields_p (t2
))
335 || (t1
!= 0 && TYPE_READONLY (t1
))
336 || (t2
!= 0 && TYPE_READONLY (t2
)))
339 /* If they are the same type, they must conflict. */
341 /* Likewise if both are volatile. */
342 || (t1
!= 0 && TYPE_VOLATILE (t1
) && t2
!= 0 && TYPE_VOLATILE (t2
)))
345 /* If one is aggregate and the other is scalar then they may not
347 if ((t1
!= 0 && AGGREGATE_TYPE_P (t1
))
348 != (t2
!= 0 && AGGREGATE_TYPE_P (t2
)))
351 /* Otherwise they conflict only if the alias sets conflict. */
352 return alias_sets_conflict_p (t1
? get_alias_set (t1
) : 0,
353 t2
? get_alias_set (t2
) : 0);
356 /* T is an expression with pointer type. Find the DECL on which this
357 expression is based. (For example, in `a[i]' this would be `a'.)
358 If there is no such DECL, or a unique decl cannot be determined,
359 NULL_TREE is returned. */
367 if (t
== 0 || t
== error_mark_node
|| ! POINTER_TYPE_P (TREE_TYPE (t
)))
370 /* If this is a declaration, return it. */
371 if (TREE_CODE_CLASS (TREE_CODE (t
)) == 'd')
374 /* Handle general expressions. It would be nice to deal with
375 COMPONENT_REFs here. If we could tell that `a' and `b' were the
376 same, then `a->f' and `b->f' are also the same. */
377 switch (TREE_CODE_CLASS (TREE_CODE (t
)))
380 return find_base_decl (TREE_OPERAND (t
, 0));
383 /* Return 0 if found in neither or both are the same. */
384 d0
= find_base_decl (TREE_OPERAND (t
, 0));
385 d1
= find_base_decl (TREE_OPERAND (t
, 1));
396 d0
= find_base_decl (TREE_OPERAND (t
, 0));
397 d1
= find_base_decl (TREE_OPERAND (t
, 1));
398 d2
= find_base_decl (TREE_OPERAND (t
, 2));
400 /* Set any nonzero values from the last, then from the first. */
401 if (d1
== 0) d1
= d2
;
402 if (d0
== 0) d0
= d1
;
403 if (d1
== 0) d1
= d0
;
404 if (d2
== 0) d2
= d1
;
406 /* At this point all are nonzero or all are zero. If all three are the
407 same, return it. Otherwise, return zero. */
408 return (d0
== d1
&& d1
== d2
) ? d0
: 0;
415 /* Return 1 if all the nested component references handled by
416 get_inner_reference in T are such that we can address the object in T. */
422 /* If we're at the end, it is vacuously addressable. */
423 if (! handled_component_p (t
))
426 /* Bitfields are never addressable. */
427 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
430 /* Fields are addressable unless they are marked as nonaddressable or
431 the containing type has alias set 0. */
432 else if (TREE_CODE (t
) == COMPONENT_REF
433 && ! DECL_NONADDRESSABLE_P (TREE_OPERAND (t
, 1))
434 && get_alias_set (TREE_TYPE (TREE_OPERAND (t
, 0))) != 0
435 && can_address_p (TREE_OPERAND (t
, 0)))
438 /* Likewise for arrays. */
439 else if ((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
440 && ! TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t
, 0)))
441 && get_alias_set (TREE_TYPE (TREE_OPERAND (t
, 0))) != 0
442 && can_address_p (TREE_OPERAND (t
, 0)))
448 /* Return the alias set for T, which may be either a type or an
449 expression. Call language-specific routine for help, if needed. */
457 /* If we're not doing any alias analysis, just assume everything
458 aliases everything else. Also return 0 if this or its type is
460 if (! flag_strict_aliasing
|| t
== error_mark_node
462 && (TREE_TYPE (t
) == 0 || TREE_TYPE (t
) == error_mark_node
)))
465 /* We can be passed either an expression or a type. This and the
466 language-specific routine may make mutually-recursive calls to each other
467 to figure out what to do. At each juncture, we see if this is a tree
468 that the language may need to handle specially. First handle things that
473 tree placeholder_ptr
= 0;
475 /* Remove any nops, then give the language a chance to do
476 something with this tree before we look at it. */
478 set
= (*lang_hooks
.get_alias_set
) (t
);
482 /* First see if the actual object referenced is an INDIRECT_REF from a
483 restrict-qualified pointer or a "void *". Replace
484 PLACEHOLDER_EXPRs. */
485 while (TREE_CODE (inner
) == PLACEHOLDER_EXPR
486 || handled_component_p (inner
))
488 if (TREE_CODE (inner
) == PLACEHOLDER_EXPR
)
489 inner
= find_placeholder (inner
, &placeholder_ptr
);
491 inner
= TREE_OPERAND (inner
, 0);
496 /* Check for accesses through restrict-qualified pointers. */
497 if (TREE_CODE (inner
) == INDIRECT_REF
)
499 tree decl
= find_base_decl (TREE_OPERAND (inner
, 0));
501 if (decl
&& DECL_POINTER_ALIAS_SET_KNOWN_P (decl
))
503 /* If we haven't computed the actual alias set, do it now. */
504 if (DECL_POINTER_ALIAS_SET (decl
) == -2)
506 /* No two restricted pointers can point at the same thing.
507 However, a restricted pointer can point at the same thing
508 as an unrestricted pointer, if that unrestricted pointer
509 is based on the restricted pointer. So, we make the
510 alias set for the restricted pointer a subset of the
511 alias set for the type pointed to by the type of the
513 HOST_WIDE_INT pointed_to_alias_set
514 = get_alias_set (TREE_TYPE (TREE_TYPE (decl
)));
516 if (pointed_to_alias_set
== 0)
517 /* It's not legal to make a subset of alias set zero. */
521 DECL_POINTER_ALIAS_SET (decl
) = new_alias_set ();
522 record_alias_subset (pointed_to_alias_set
,
523 DECL_POINTER_ALIAS_SET (decl
));
527 /* We use the alias set indicated in the declaration. */
528 return DECL_POINTER_ALIAS_SET (decl
);
531 /* If we have an INDIRECT_REF via a void pointer, we don't
532 know anything about what that might alias. */
533 else if (TREE_CODE (TREE_TYPE (inner
)) == VOID_TYPE
)
537 /* Otherwise, pick up the outermost object that we could have a pointer
538 to, processing conversion and PLACEHOLDER_EXPR as above. */
540 while (TREE_CODE (t
) == PLACEHOLDER_EXPR
541 || (handled_component_p (t
) && ! can_address_p (t
)))
543 if (TREE_CODE (t
) == PLACEHOLDER_EXPR
)
544 t
= find_placeholder (t
, &placeholder_ptr
);
546 t
= TREE_OPERAND (t
, 0);
551 /* If we've already determined the alias set for a decl, just return
552 it. This is necessary for C++ anonymous unions, whose component
553 variables don't look like union members (boo!). */
554 if (TREE_CODE (t
) == VAR_DECL
555 && DECL_RTL_SET_P (t
) && GET_CODE (DECL_RTL (t
)) == MEM
)
556 return MEM_ALIAS_SET (DECL_RTL (t
));
558 /* Now all we care about is the type. */
562 /* Variant qualifiers don't affect the alias set, so get the main
563 variant. If this is a type with a known alias set, return it. */
564 t
= TYPE_MAIN_VARIANT (t
);
565 if (TYPE_ALIAS_SET_KNOWN_P (t
))
566 return TYPE_ALIAS_SET (t
);
568 /* See if the language has special handling for this type. */
569 set
= (*lang_hooks
.get_alias_set
) (t
);
573 /* There are no objects of FUNCTION_TYPE, so there's no point in
574 using up an alias set for them. (There are, of course, pointers
575 and references to functions, but that's different.) */
576 else if (TREE_CODE (t
) == FUNCTION_TYPE
)
579 /* Unless the language specifies otherwise, let vector types alias
580 their components. This avoids some nasty type punning issues in
581 normal usage. And indeed lets vectors be treated more like an
583 else if (TREE_CODE (t
) == VECTOR_TYPE
)
584 set
= get_alias_set (TREE_TYPE (t
));
587 /* Otherwise make a new alias set for this type. */
588 set
= new_alias_set ();
590 TYPE_ALIAS_SET (t
) = set
;
592 /* If this is an aggregate type, we must record any component aliasing
594 if (AGGREGATE_TYPE_P (t
) || TREE_CODE (t
) == COMPLEX_TYPE
)
595 record_component_aliases (t
);
600 /* Return a brand-new alias set. */
605 static HOST_WIDE_INT last_alias_set
;
607 if (flag_strict_aliasing
)
608 return ++last_alias_set
;
613 /* Indicate that things in SUBSET can alias things in SUPERSET, but
614 not vice versa. For example, in C, a store to an `int' can alias a
615 structure containing an `int', but not vice versa. Here, the
616 structure would be the SUPERSET and `int' the SUBSET. This
617 function should be called only once per SUPERSET/SUBSET pair.
619 It is illegal for SUPERSET to be zero; everything is implicitly a
620 subset of alias set zero. */
623 record_alias_subset (superset
, subset
)
624 HOST_WIDE_INT superset
;
625 HOST_WIDE_INT subset
;
627 alias_set_entry superset_entry
;
628 alias_set_entry subset_entry
;
630 /* It is possible in complex type situations for both sets to be the same,
631 in which case we can ignore this operation. */
632 if (superset
== subset
)
638 superset_entry
= get_alias_set_entry (superset
);
639 if (superset_entry
== 0)
641 /* Create an entry for the SUPERSET, so that we have a place to
642 attach the SUBSET. */
644 = (alias_set_entry
) xmalloc (sizeof (struct alias_set_entry
));
645 superset_entry
->alias_set
= superset
;
646 superset_entry
->children
647 = splay_tree_new (splay_tree_compare_ints
, 0, 0);
648 superset_entry
->has_zero_child
= 0;
649 splay_tree_insert (alias_sets
, (splay_tree_key
) superset
,
650 (splay_tree_value
) superset_entry
);
654 superset_entry
->has_zero_child
= 1;
657 subset_entry
= get_alias_set_entry (subset
);
658 /* If there is an entry for the subset, enter all of its children
659 (if they are not already present) as children of the SUPERSET. */
662 if (subset_entry
->has_zero_child
)
663 superset_entry
->has_zero_child
= 1;
665 splay_tree_foreach (subset_entry
->children
, insert_subset_children
,
666 superset_entry
->children
);
669 /* Enter the SUBSET itself as a child of the SUPERSET. */
670 splay_tree_insert (superset_entry
->children
,
671 (splay_tree_key
) subset
, 0);
675 /* Record that component types of TYPE, if any, are part of that type for
676 aliasing purposes. For record types, we only record component types
677 for fields that are marked addressable. For array types, we always
678 record the component types, so the front end should not call this
679 function if the individual component aren't addressable. */
682 record_component_aliases (type
)
685 HOST_WIDE_INT superset
= get_alias_set (type
);
691 switch (TREE_CODE (type
))
694 if (! TYPE_NONALIASED_COMPONENT (type
))
695 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
700 case QUAL_UNION_TYPE
:
701 /* Recursively record aliases for the base classes, if there are any */
702 if (TYPE_BINFO (type
) != NULL
&& TYPE_BINFO_BASETYPES (type
) != NULL
)
705 for (i
= 0; i
< TREE_VEC_LENGTH (TYPE_BINFO_BASETYPES (type
)); i
++)
707 tree binfo
= TREE_VEC_ELT (TYPE_BINFO_BASETYPES (type
), i
);
708 record_alias_subset (superset
,
709 get_alias_set (BINFO_TYPE (binfo
)));
712 for (field
= TYPE_FIELDS (type
); field
!= 0; field
= TREE_CHAIN (field
))
713 if (TREE_CODE (field
) == FIELD_DECL
&& ! DECL_NONADDRESSABLE_P (field
))
714 record_alias_subset (superset
, get_alias_set (TREE_TYPE (field
)));
718 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
726 /* Allocate an alias set for use in storing and reading from the varargs
730 get_varargs_alias_set ()
732 static HOST_WIDE_INT set
= -1;
735 set
= new_alias_set ();
740 /* Likewise, but used for the fixed portions of the frame, e.g., register
744 get_frame_alias_set ()
746 static HOST_WIDE_INT set
= -1;
749 set
= new_alias_set ();
754 /* Inside SRC, the source of a SET, find a base address. */
757 find_base_value (src
)
762 switch (GET_CODE (src
))
770 /* At the start of a function, argument registers have known base
771 values which may be lost later. Returning an ADDRESS
772 expression here allows optimization based on argument values
773 even when the argument registers are used for other purposes. */
774 if (regno
< FIRST_PSEUDO_REGISTER
&& copying_arguments
)
775 return new_reg_base_value
[regno
];
777 /* If a pseudo has a known base value, return it. Do not do this
778 for non-fixed hard regs since it can result in a circular
779 dependency chain for registers which have values at function entry.
781 The test above is not sufficient because the scheduler may move
782 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
783 if ((regno
>= FIRST_PSEUDO_REGISTER
|| fixed_regs
[regno
])
784 && regno
< reg_base_value_size
785 && reg_base_value
[regno
])
786 return reg_base_value
[regno
];
791 /* Check for an argument passed in memory. Only record in the
792 copying-arguments block; it is too hard to track changes
794 if (copying_arguments
795 && (XEXP (src
, 0) == arg_pointer_rtx
796 || (GET_CODE (XEXP (src
, 0)) == PLUS
797 && XEXP (XEXP (src
, 0), 0) == arg_pointer_rtx
)))
798 return gen_rtx_ADDRESS (VOIDmode
, src
);
803 if (GET_CODE (src
) != PLUS
&& GET_CODE (src
) != MINUS
)
806 /* ... fall through ... */
811 rtx temp
, src_0
= XEXP (src
, 0), src_1
= XEXP (src
, 1);
813 /* If either operand is a REG that is a known pointer, then it
815 if (REG_P (src_0
) && REG_POINTER (src_0
))
816 return find_base_value (src_0
);
817 if (REG_P (src_1
) && REG_POINTER (src_1
))
818 return find_base_value (src_1
);
820 /* If either operand is a REG, then see if we already have
821 a known value for it. */
824 temp
= find_base_value (src_0
);
831 temp
= find_base_value (src_1
);
836 /* If either base is named object or a special address
837 (like an argument or stack reference), then use it for the
840 && (GET_CODE (src_0
) == SYMBOL_REF
841 || GET_CODE (src_0
) == LABEL_REF
842 || (GET_CODE (src_0
) == ADDRESS
843 && GET_MODE (src_0
) != VOIDmode
)))
847 && (GET_CODE (src_1
) == SYMBOL_REF
848 || GET_CODE (src_1
) == LABEL_REF
849 || (GET_CODE (src_1
) == ADDRESS
850 && GET_MODE (src_1
) != VOIDmode
)))
853 /* Guess which operand is the base address:
854 If either operand is a symbol, then it is the base. If
855 either operand is a CONST_INT, then the other is the base. */
856 if (GET_CODE (src_1
) == CONST_INT
|| CONSTANT_P (src_0
))
857 return find_base_value (src_0
);
858 else if (GET_CODE (src_0
) == CONST_INT
|| CONSTANT_P (src_1
))
859 return find_base_value (src_1
);
865 /* The standard form is (lo_sum reg sym) so look only at the
867 return find_base_value (XEXP (src
, 1));
870 /* If the second operand is constant set the base
871 address to the first operand. */
872 if (GET_CODE (XEXP (src
, 1)) == CONST_INT
&& INTVAL (XEXP (src
, 1)) != 0)
873 return find_base_value (XEXP (src
, 0));
877 if (GET_MODE_SIZE (GET_MODE (src
)) < GET_MODE_SIZE (Pmode
))
887 return find_base_value (XEXP (src
, 0));
890 case SIGN_EXTEND
: /* used for NT/Alpha pointers */
892 rtx temp
= find_base_value (XEXP (src
, 0));
894 #ifdef POINTERS_EXTEND_UNSIGNED
895 if (temp
!= 0 && CONSTANT_P (temp
) && GET_MODE (temp
) != Pmode
)
896 temp
= convert_memory_address (Pmode
, temp
);
909 /* Called from init_alias_analysis indirectly through note_stores. */
911 /* While scanning insns to find base values, reg_seen[N] is nonzero if
912 register N has been set in this function. */
913 static char *reg_seen
;
915 /* Addresses which are known not to alias anything else are identified
916 by a unique integer. */
917 static int unique_id
;
920 record_set (dest
, set
, data
)
922 void *data ATTRIBUTE_UNUSED
;
927 if (GET_CODE (dest
) != REG
)
930 regno
= REGNO (dest
);
932 if (regno
>= reg_base_value_size
)
937 /* A CLOBBER wipes out any old value but does not prevent a previously
938 unset register from acquiring a base address (i.e. reg_seen is not
940 if (GET_CODE (set
) == CLOBBER
)
942 new_reg_base_value
[regno
] = 0;
951 new_reg_base_value
[regno
] = 0;
955 new_reg_base_value
[regno
] = gen_rtx_ADDRESS (Pmode
,
956 GEN_INT (unique_id
++));
960 /* This is not the first set. If the new value is not related to the
961 old value, forget the base value. Note that the following code is
963 extern int x, y; int *p = &x; p += (&y-&x);
964 ANSI C does not allow computing the difference of addresses
965 of distinct top level objects. */
966 if (new_reg_base_value
[regno
])
967 switch (GET_CODE (src
))
971 if (XEXP (src
, 0) != dest
&& XEXP (src
, 1) != dest
)
972 new_reg_base_value
[regno
] = 0;
975 /* If the value we add in the PLUS is also a valid base value,
976 this might be the actual base value, and the original value
979 rtx other
= NULL_RTX
;
981 if (XEXP (src
, 0) == dest
)
982 other
= XEXP (src
, 1);
983 else if (XEXP (src
, 1) == dest
)
984 other
= XEXP (src
, 0);
986 if (! other
|| find_base_value (other
))
987 new_reg_base_value
[regno
] = 0;
991 if (XEXP (src
, 0) != dest
|| GET_CODE (XEXP (src
, 1)) != CONST_INT
)
992 new_reg_base_value
[regno
] = 0;
995 new_reg_base_value
[regno
] = 0;
998 /* If this is the first set of a register, record the value. */
999 else if ((regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
1000 && ! reg_seen
[regno
] && new_reg_base_value
[regno
] == 0)
1001 new_reg_base_value
[regno
] = find_base_value (src
);
1003 reg_seen
[regno
] = 1;
1006 /* Called from loop optimization when a new pseudo-register is
1007 created. It indicates that REGNO is being set to VAL. f INVARIANT
1008 is true then this value also describes an invariant relationship
1009 which can be used to deduce that two registers with unknown values
1013 record_base_value (regno
, val
, invariant
)
1018 if (regno
>= reg_base_value_size
)
1021 if (invariant
&& alias_invariant
)
1022 alias_invariant
[regno
] = val
;
1024 if (GET_CODE (val
) == REG
)
1026 if (REGNO (val
) < reg_base_value_size
)
1027 reg_base_value
[regno
] = reg_base_value
[REGNO (val
)];
1032 reg_base_value
[regno
] = find_base_value (val
);
1035 /* Clear alias info for a register. This is used if an RTL transformation
1036 changes the value of a register. This is used in flow by AUTO_INC_DEC
1037 optimizations. We don't need to clear reg_base_value, since flow only
1038 changes the offset. */
1041 clear_reg_alias_info (reg
)
1044 unsigned int regno
= REGNO (reg
);
1046 if (regno
< reg_known_value_size
&& regno
>= FIRST_PSEUDO_REGISTER
)
1047 reg_known_value
[regno
] = reg
;
1050 /* Returns a canonical version of X, from the point of view alias
1051 analysis. (For example, if X is a MEM whose address is a register,
1052 and the register has a known value (say a SYMBOL_REF), then a MEM
1053 whose address is the SYMBOL_REF is returned.) */
1059 /* Recursively look for equivalences. */
1060 if (GET_CODE (x
) == REG
&& REGNO (x
) >= FIRST_PSEUDO_REGISTER
1061 && REGNO (x
) < reg_known_value_size
)
1062 return reg_known_value
[REGNO (x
)] == x
1063 ? x
: canon_rtx (reg_known_value
[REGNO (x
)]);
1064 else if (GET_CODE (x
) == PLUS
)
1066 rtx x0
= canon_rtx (XEXP (x
, 0));
1067 rtx x1
= canon_rtx (XEXP (x
, 1));
1069 if (x0
!= XEXP (x
, 0) || x1
!= XEXP (x
, 1))
1071 if (GET_CODE (x0
) == CONST_INT
)
1072 return plus_constant (x1
, INTVAL (x0
));
1073 else if (GET_CODE (x1
) == CONST_INT
)
1074 return plus_constant (x0
, INTVAL (x1
));
1075 return gen_rtx_PLUS (GET_MODE (x
), x0
, x1
);
1079 /* This gives us much better alias analysis when called from
1080 the loop optimizer. Note we want to leave the original
1081 MEM alone, but need to return the canonicalized MEM with
1082 all the flags with their original values. */
1083 else if (GET_CODE (x
) == MEM
)
1084 x
= replace_equiv_address_nv (x
, canon_rtx (XEXP (x
, 0)));
1089 /* Return 1 if X and Y are identical-looking rtx's.
1091 We use the data in reg_known_value above to see if two registers with
1092 different numbers are, in fact, equivalent. */
1095 rtx_equal_for_memref_p (x
, y
)
1103 if (x
== 0 && y
== 0)
1105 if (x
== 0 || y
== 0)
1114 code
= GET_CODE (x
);
1115 /* Rtx's of different codes cannot be equal. */
1116 if (code
!= GET_CODE (y
))
1119 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1120 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1122 if (GET_MODE (x
) != GET_MODE (y
))
1125 /* Some RTL can be compared without a recursive examination. */
1129 return CSELIB_VAL_PTR (x
) == CSELIB_VAL_PTR (y
);
1132 return REGNO (x
) == REGNO (y
);
1135 return XEXP (x
, 0) == XEXP (y
, 0);
1138 return XSTR (x
, 0) == XSTR (y
, 0);
1142 /* There's no need to compare the contents of CONST_DOUBLEs or
1143 CONST_INTs because pointer equality is a good enough
1144 comparison for these nodes. */
1148 return (XINT (x
, 1) == XINT (y
, 1)
1149 && rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0)));
1155 /* For commutative operations, the RTX match if the operand match in any
1156 order. Also handle the simple binary and unary cases without a loop. */
1157 if (code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c')
1158 return ((rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0))
1159 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 1)))
1160 || (rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 1))
1161 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 0))));
1162 else if (GET_RTX_CLASS (code
) == '<' || GET_RTX_CLASS (code
) == '2')
1163 return (rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0))
1164 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 1)));
1165 else if (GET_RTX_CLASS (code
) == '1')
1166 return rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0));
1168 /* Compare the elements. If any pair of corresponding elements
1169 fail to match, return 0 for the whole things.
1171 Limit cases to types which actually appear in addresses. */
1173 fmt
= GET_RTX_FORMAT (code
);
1174 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1179 if (XINT (x
, i
) != XINT (y
, i
))
1184 /* Two vectors must have the same length. */
1185 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1188 /* And the corresponding elements must match. */
1189 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1190 if (rtx_equal_for_memref_p (XVECEXP (x
, i
, j
),
1191 XVECEXP (y
, i
, j
)) == 0)
1196 if (rtx_equal_for_memref_p (XEXP (x
, i
), XEXP (y
, i
)) == 0)
1200 /* This can happen for asm operands. */
1202 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1206 /* This can happen for an asm which clobbers memory. */
1210 /* It is believed that rtx's at this level will never
1211 contain anything but integers and other rtx's,
1212 except for within LABEL_REFs and SYMBOL_REFs. */
1220 /* Given an rtx X, find a SYMBOL_REF or LABEL_REF within
1221 X and return it, or return 0 if none found. */
1224 find_symbolic_term (x
)
1231 code
= GET_CODE (x
);
1232 if (code
== SYMBOL_REF
|| code
== LABEL_REF
)
1234 if (GET_RTX_CLASS (code
) == 'o')
1237 fmt
= GET_RTX_FORMAT (code
);
1238 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1244 t
= find_symbolic_term (XEXP (x
, i
));
1248 else if (fmt
[i
] == 'E')
1259 struct elt_loc_list
*l
;
1261 #if defined (FIND_BASE_TERM)
1262 /* Try machine-dependent ways to find the base term. */
1263 x
= FIND_BASE_TERM (x
);
1266 switch (GET_CODE (x
))
1269 return REG_BASE_VALUE (x
);
1272 if (GET_MODE_SIZE (GET_MODE (x
)) < GET_MODE_SIZE (Pmode
))
1282 return find_base_term (XEXP (x
, 0));
1285 case SIGN_EXTEND
: /* Used for Alpha/NT pointers */
1287 rtx temp
= find_base_term (XEXP (x
, 0));
1289 #ifdef POINTERS_EXTEND_UNSIGNED
1290 if (temp
!= 0 && CONSTANT_P (temp
) && GET_MODE (temp
) != Pmode
)
1291 temp
= convert_memory_address (Pmode
, temp
);
1298 val
= CSELIB_VAL_PTR (x
);
1299 for (l
= val
->locs
; l
; l
= l
->next
)
1300 if ((x
= find_base_term (l
->loc
)) != 0)
1306 if (GET_CODE (x
) != PLUS
&& GET_CODE (x
) != MINUS
)
1313 rtx tmp1
= XEXP (x
, 0);
1314 rtx tmp2
= XEXP (x
, 1);
1316 /* This is a little bit tricky since we have to determine which of
1317 the two operands represents the real base address. Otherwise this
1318 routine may return the index register instead of the base register.
1320 That may cause us to believe no aliasing was possible, when in
1321 fact aliasing is possible.
1323 We use a few simple tests to guess the base register. Additional
1324 tests can certainly be added. For example, if one of the operands
1325 is a shift or multiply, then it must be the index register and the
1326 other operand is the base register. */
1328 if (tmp1
== pic_offset_table_rtx
&& CONSTANT_P (tmp2
))
1329 return find_base_term (tmp2
);
1331 /* If either operand is known to be a pointer, then use it
1332 to determine the base term. */
1333 if (REG_P (tmp1
) && REG_POINTER (tmp1
))
1334 return find_base_term (tmp1
);
1336 if (REG_P (tmp2
) && REG_POINTER (tmp2
))
1337 return find_base_term (tmp2
);
1339 /* Neither operand was known to be a pointer. Go ahead and find the
1340 base term for both operands. */
1341 tmp1
= find_base_term (tmp1
);
1342 tmp2
= find_base_term (tmp2
);
1344 /* If either base term is named object or a special address
1345 (like an argument or stack reference), then use it for the
1348 && (GET_CODE (tmp1
) == SYMBOL_REF
1349 || GET_CODE (tmp1
) == LABEL_REF
1350 || (GET_CODE (tmp1
) == ADDRESS
1351 && GET_MODE (tmp1
) != VOIDmode
)))
1355 && (GET_CODE (tmp2
) == SYMBOL_REF
1356 || GET_CODE (tmp2
) == LABEL_REF
1357 || (GET_CODE (tmp2
) == ADDRESS
1358 && GET_MODE (tmp2
) != VOIDmode
)))
1361 /* We could not determine which of the two operands was the
1362 base register and which was the index. So we can determine
1363 nothing from the base alias check. */
1368 if (GET_CODE (XEXP (x
, 1)) == CONST_INT
&& INTVAL (XEXP (x
, 1)) != 0)
1369 return find_base_term (XEXP (x
, 0));
1377 return REG_BASE_VALUE (frame_pointer_rtx
);
1384 /* Return 0 if the addresses X and Y are known to point to different
1385 objects, 1 if they might be pointers to the same object. */
1388 base_alias_check (x
, y
, x_mode
, y_mode
)
1390 enum machine_mode x_mode
, y_mode
;
1392 rtx x_base
= find_base_term (x
);
1393 rtx y_base
= find_base_term (y
);
1395 /* If the address itself has no known base see if a known equivalent
1396 value has one. If either address still has no known base, nothing
1397 is known about aliasing. */
1402 if (! flag_expensive_optimizations
|| (x_c
= canon_rtx (x
)) == x
)
1405 x_base
= find_base_term (x_c
);
1413 if (! flag_expensive_optimizations
|| (y_c
= canon_rtx (y
)) == y
)
1416 y_base
= find_base_term (y_c
);
1421 /* If the base addresses are equal nothing is known about aliasing. */
1422 if (rtx_equal_p (x_base
, y_base
))
1425 /* The base addresses of the read and write are different expressions.
1426 If they are both symbols and they are not accessed via AND, there is
1427 no conflict. We can bring knowledge of object alignment into play
1428 here. For example, on alpha, "char a, b;" can alias one another,
1429 though "char a; long b;" cannot. */
1430 if (GET_CODE (x_base
) != ADDRESS
&& GET_CODE (y_base
) != ADDRESS
)
1432 if (GET_CODE (x
) == AND
&& GET_CODE (y
) == AND
)
1434 if (GET_CODE (x
) == AND
1435 && (GET_CODE (XEXP (x
, 1)) != CONST_INT
1436 || (int) GET_MODE_UNIT_SIZE (y_mode
) < -INTVAL (XEXP (x
, 1))))
1438 if (GET_CODE (y
) == AND
1439 && (GET_CODE (XEXP (y
, 1)) != CONST_INT
1440 || (int) GET_MODE_UNIT_SIZE (x_mode
) < -INTVAL (XEXP (y
, 1))))
1442 /* Differing symbols never alias. */
1446 /* If one address is a stack reference there can be no alias:
1447 stack references using different base registers do not alias,
1448 a stack reference can not alias a parameter, and a stack reference
1449 can not alias a global. */
1450 if ((GET_CODE (x_base
) == ADDRESS
&& GET_MODE (x_base
) == Pmode
)
1451 || (GET_CODE (y_base
) == ADDRESS
&& GET_MODE (y_base
) == Pmode
))
1454 if (! flag_argument_noalias
)
1457 if (flag_argument_noalias
> 1)
1460 /* Weak noalias assertion (arguments are distinct, but may match globals). */
1461 return ! (GET_MODE (x_base
) == VOIDmode
&& GET_MODE (y_base
) == VOIDmode
);
1464 /* Convert the address X into something we can use. This is done by returning
1465 it unchanged unless it is a value; in the latter case we call cselib to get
1466 a more useful rtx. */
1473 struct elt_loc_list
*l
;
1475 if (GET_CODE (x
) != VALUE
)
1477 v
= CSELIB_VAL_PTR (x
);
1478 for (l
= v
->locs
; l
; l
= l
->next
)
1479 if (CONSTANT_P (l
->loc
))
1481 for (l
= v
->locs
; l
; l
= l
->next
)
1482 if (GET_CODE (l
->loc
) != REG
&& GET_CODE (l
->loc
) != MEM
)
1485 return v
->locs
->loc
;
1489 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
1490 where SIZE is the size in bytes of the memory reference. If ADDR
1491 is not modified by the memory reference then ADDR is returned. */
1494 addr_side_effect_eval (addr
, size
, n_refs
)
1501 switch (GET_CODE (addr
))
1504 offset
= (n_refs
+ 1) * size
;
1507 offset
= -(n_refs
+ 1) * size
;
1510 offset
= n_refs
* size
;
1513 offset
= -n_refs
* size
;
1521 addr
= gen_rtx_PLUS (GET_MODE (addr
), XEXP (addr
, 0), GEN_INT (offset
));
1523 addr
= XEXP (addr
, 0);
1528 /* Return nonzero if X and Y (memory addresses) could reference the
1529 same location in memory. C is an offset accumulator. When
1530 C is nonzero, we are testing aliases between X and Y + C.
1531 XSIZE is the size in bytes of the X reference,
1532 similarly YSIZE is the size in bytes for Y.
1534 If XSIZE or YSIZE is zero, we do not know the amount of memory being
1535 referenced (the reference was BLKmode), so make the most pessimistic
1538 If XSIZE or YSIZE is negative, we may access memory outside the object
1539 being referenced as a side effect. This can happen when using AND to
1540 align memory references, as is done on the Alpha.
1542 Nice to notice that varying addresses cannot conflict with fp if no
1543 local variables had their addresses taken, but that's too hard now. */
1546 memrefs_conflict_p (xsize
, x
, ysize
, y
, c
)
1551 if (GET_CODE (x
) == VALUE
)
1553 if (GET_CODE (y
) == VALUE
)
1555 if (GET_CODE (x
) == HIGH
)
1557 else if (GET_CODE (x
) == LO_SUM
)
1560 x
= canon_rtx (addr_side_effect_eval (x
, xsize
, 0));
1561 if (GET_CODE (y
) == HIGH
)
1563 else if (GET_CODE (y
) == LO_SUM
)
1566 y
= canon_rtx (addr_side_effect_eval (y
, ysize
, 0));
1568 if (rtx_equal_for_memref_p (x
, y
))
1570 if (xsize
<= 0 || ysize
<= 0)
1572 if (c
>= 0 && xsize
> c
)
1574 if (c
< 0 && ysize
+c
> 0)
1579 /* This code used to check for conflicts involving stack references and
1580 globals but the base address alias code now handles these cases. */
1582 if (GET_CODE (x
) == PLUS
)
1584 /* The fact that X is canonicalized means that this
1585 PLUS rtx is canonicalized. */
1586 rtx x0
= XEXP (x
, 0);
1587 rtx x1
= XEXP (x
, 1);
1589 if (GET_CODE (y
) == PLUS
)
1591 /* The fact that Y is canonicalized means that this
1592 PLUS rtx is canonicalized. */
1593 rtx y0
= XEXP (y
, 0);
1594 rtx y1
= XEXP (y
, 1);
1596 if (rtx_equal_for_memref_p (x1
, y1
))
1597 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
1598 if (rtx_equal_for_memref_p (x0
, y0
))
1599 return memrefs_conflict_p (xsize
, x1
, ysize
, y1
, c
);
1600 if (GET_CODE (x1
) == CONST_INT
)
1602 if (GET_CODE (y1
) == CONST_INT
)
1603 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
,
1604 c
- INTVAL (x1
) + INTVAL (y1
));
1606 return memrefs_conflict_p (xsize
, x0
, ysize
, y
,
1609 else if (GET_CODE (y1
) == CONST_INT
)
1610 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
1614 else if (GET_CODE (x1
) == CONST_INT
)
1615 return memrefs_conflict_p (xsize
, x0
, ysize
, y
, c
- INTVAL (x1
));
1617 else if (GET_CODE (y
) == PLUS
)
1619 /* The fact that Y is canonicalized means that this
1620 PLUS rtx is canonicalized. */
1621 rtx y0
= XEXP (y
, 0);
1622 rtx y1
= XEXP (y
, 1);
1624 if (GET_CODE (y1
) == CONST_INT
)
1625 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
1630 if (GET_CODE (x
) == GET_CODE (y
))
1631 switch (GET_CODE (x
))
1635 /* Handle cases where we expect the second operands to be the
1636 same, and check only whether the first operand would conflict
1639 rtx x1
= canon_rtx (XEXP (x
, 1));
1640 rtx y1
= canon_rtx (XEXP (y
, 1));
1641 if (! rtx_equal_for_memref_p (x1
, y1
))
1643 x0
= canon_rtx (XEXP (x
, 0));
1644 y0
= canon_rtx (XEXP (y
, 0));
1645 if (rtx_equal_for_memref_p (x0
, y0
))
1646 return (xsize
== 0 || ysize
== 0
1647 || (c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0));
1649 /* Can't properly adjust our sizes. */
1650 if (GET_CODE (x1
) != CONST_INT
)
1652 xsize
/= INTVAL (x1
);
1653 ysize
/= INTVAL (x1
);
1655 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
1659 /* Are these registers known not to be equal? */
1660 if (alias_invariant
)
1662 unsigned int r_x
= REGNO (x
), r_y
= REGNO (y
);
1663 rtx i_x
, i_y
; /* invariant relationships of X and Y */
1665 i_x
= r_x
>= reg_base_value_size
? 0 : alias_invariant
[r_x
];
1666 i_y
= r_y
>= reg_base_value_size
? 0 : alias_invariant
[r_y
];
1668 if (i_x
== 0 && i_y
== 0)
1671 if (! memrefs_conflict_p (xsize
, i_x
? i_x
: x
,
1672 ysize
, i_y
? i_y
: y
, c
))
1681 /* Treat an access through an AND (e.g. a subword access on an Alpha)
1682 as an access with indeterminate size. Assume that references
1683 besides AND are aligned, so if the size of the other reference is
1684 at least as large as the alignment, assume no other overlap. */
1685 if (GET_CODE (x
) == AND
&& GET_CODE (XEXP (x
, 1)) == CONST_INT
)
1687 if (GET_CODE (y
) == AND
|| ysize
< -INTVAL (XEXP (x
, 1)))
1689 return memrefs_conflict_p (xsize
, XEXP (x
, 0), ysize
, y
, c
);
1691 if (GET_CODE (y
) == AND
&& GET_CODE (XEXP (y
, 1)) == CONST_INT
)
1693 /* ??? If we are indexing far enough into the array/structure, we
1694 may yet be able to determine that we can not overlap. But we
1695 also need to that we are far enough from the end not to overlap
1696 a following reference, so we do nothing with that for now. */
1697 if (GET_CODE (x
) == AND
|| xsize
< -INTVAL (XEXP (y
, 1)))
1699 return memrefs_conflict_p (xsize
, x
, ysize
, XEXP (y
, 0), c
);
1702 if (GET_CODE (x
) == ADDRESSOF
)
1704 if (y
== frame_pointer_rtx
1705 || GET_CODE (y
) == ADDRESSOF
)
1706 return xsize
<= 0 || ysize
<= 0;
1708 if (GET_CODE (y
) == ADDRESSOF
)
1710 if (x
== frame_pointer_rtx
)
1711 return xsize
<= 0 || ysize
<= 0;
1716 if (GET_CODE (x
) == CONST_INT
&& GET_CODE (y
) == CONST_INT
)
1718 c
+= (INTVAL (y
) - INTVAL (x
));
1719 return (xsize
<= 0 || ysize
<= 0
1720 || (c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0));
1723 if (GET_CODE (x
) == CONST
)
1725 if (GET_CODE (y
) == CONST
)
1726 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
1727 ysize
, canon_rtx (XEXP (y
, 0)), c
);
1729 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
1732 if (GET_CODE (y
) == CONST
)
1733 return memrefs_conflict_p (xsize
, x
, ysize
,
1734 canon_rtx (XEXP (y
, 0)), c
);
1737 return (xsize
<= 0 || ysize
<= 0
1738 || (rtx_equal_for_memref_p (x
, y
)
1739 && ((c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0))));
1746 /* Functions to compute memory dependencies.
1748 Since we process the insns in execution order, we can build tables
1749 to keep track of what registers are fixed (and not aliased), what registers
1750 are varying in known ways, and what registers are varying in unknown
1753 If both memory references are volatile, then there must always be a
1754 dependence between the two references, since their order can not be
1755 changed. A volatile and non-volatile reference can be interchanged
1758 A MEM_IN_STRUCT reference at a non-AND varying address can never
1759 conflict with a non-MEM_IN_STRUCT reference at a fixed address. We
1760 also must allow AND addresses, because they may generate accesses
1761 outside the object being referenced. This is used to generate
1762 aligned addresses from unaligned addresses, for instance, the alpha
1763 storeqi_unaligned pattern. */
1765 /* Read dependence: X is read after read in MEM takes place. There can
1766 only be a dependence here if both reads are volatile. */
1769 read_dependence (mem
, x
)
1773 return MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
);
1776 /* Returns MEM1 if and only if MEM1 is a scalar at a fixed address and
1777 MEM2 is a reference to a structure at a varying address, or returns
1778 MEM2 if vice versa. Otherwise, returns NULL_RTX. If a non-NULL
1779 value is returned MEM1 and MEM2 can never alias. VARIES_P is used
1780 to decide whether or not an address may vary; it should return
1781 nonzero whenever variation is possible.
1782 MEM1_ADDR and MEM2_ADDR are the addresses of MEM1 and MEM2. */
1785 fixed_scalar_and_varying_struct_p (mem1
, mem2
, mem1_addr
, mem2_addr
, varies_p
)
1787 rtx mem1_addr
, mem2_addr
;
1788 int (*varies_p
) PARAMS ((rtx
, int));
1790 if (! flag_strict_aliasing
)
1793 if (MEM_SCALAR_P (mem1
) && MEM_IN_STRUCT_P (mem2
)
1794 && !varies_p (mem1_addr
, 1) && varies_p (mem2_addr
, 1))
1795 /* MEM1 is a scalar at a fixed address; MEM2 is a struct at a
1799 if (MEM_IN_STRUCT_P (mem1
) && MEM_SCALAR_P (mem2
)
1800 && varies_p (mem1_addr
, 1) && !varies_p (mem2_addr
, 1))
1801 /* MEM2 is a scalar at a fixed address; MEM1 is a struct at a
1808 /* Returns nonzero if something about the mode or address format MEM1
1809 indicates that it might well alias *anything*. */
1812 aliases_everything_p (mem
)
1815 if (GET_CODE (XEXP (mem
, 0)) == AND
)
1816 /* If the address is an AND, its very hard to know at what it is
1817 actually pointing. */
1823 /* Return true if we can determine that the fields referenced cannot
1824 overlap for any pair of objects. */
1827 nonoverlapping_component_refs_p (x
, y
)
1830 tree fieldx
, fieldy
, typex
, typey
, orig_y
;
1834 /* The comparison has to be done at a common type, since we don't
1835 know how the inheritance hierarchy works. */
1839 fieldx
= TREE_OPERAND (x
, 1);
1840 typex
= DECL_FIELD_CONTEXT (fieldx
);
1845 fieldy
= TREE_OPERAND (y
, 1);
1846 typey
= DECL_FIELD_CONTEXT (fieldy
);
1851 y
= TREE_OPERAND (y
, 0);
1853 while (y
&& TREE_CODE (y
) == COMPONENT_REF
);
1855 x
= TREE_OPERAND (x
, 0);
1857 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
1859 /* Never found a common type. */
1863 /* If we're left with accessing different fields of a structure,
1865 if (TREE_CODE (typex
) == RECORD_TYPE
1866 && fieldx
!= fieldy
)
1869 /* The comparison on the current field failed. If we're accessing
1870 a very nested structure, look at the next outer level. */
1871 x
= TREE_OPERAND (x
, 0);
1872 y
= TREE_OPERAND (y
, 0);
1875 && TREE_CODE (x
) == COMPONENT_REF
1876 && TREE_CODE (y
) == COMPONENT_REF
);
1881 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
1884 decl_for_component_ref (x
)
1889 x
= TREE_OPERAND (x
, 0);
1891 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
1893 return x
&& DECL_P (x
) ? x
: NULL_TREE
;
1896 /* Walk up the COMPONENT_REF list and adjust OFFSET to compensate for the
1897 offset of the field reference. */
1900 adjust_offset_for_component_ref (x
, offset
)
1904 HOST_WIDE_INT ioffset
;
1909 ioffset
= INTVAL (offset
);
1912 tree field
= TREE_OPERAND (x
, 1);
1914 if (! host_integerp (DECL_FIELD_OFFSET (field
), 1))
1916 ioffset
+= (tree_low_cst (DECL_FIELD_OFFSET (field
), 1)
1917 + (tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1)
1920 x
= TREE_OPERAND (x
, 0);
1922 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
1924 return GEN_INT (ioffset
);
1927 /* Return nonzero if we can deterimine the exprs corresponding to memrefs
1928 X and Y and they do not overlap. */
1931 nonoverlapping_memrefs_p (x
, y
)
1934 tree exprx
= MEM_EXPR (x
), expry
= MEM_EXPR (y
);
1937 rtx moffsetx
, moffsety
;
1938 HOST_WIDE_INT offsetx
= 0, offsety
= 0, sizex
, sizey
, tem
;
1940 /* Unless both have exprs, we can't tell anything. */
1941 if (exprx
== 0 || expry
== 0)
1944 /* If both are field references, we may be able to determine something. */
1945 if (TREE_CODE (exprx
) == COMPONENT_REF
1946 && TREE_CODE (expry
) == COMPONENT_REF
1947 && nonoverlapping_component_refs_p (exprx
, expry
))
1950 /* If the field reference test failed, look at the DECLs involved. */
1951 moffsetx
= MEM_OFFSET (x
);
1952 if (TREE_CODE (exprx
) == COMPONENT_REF
)
1954 tree t
= decl_for_component_ref (exprx
);
1957 moffsetx
= adjust_offset_for_component_ref (exprx
, moffsetx
);
1960 moffsety
= MEM_OFFSET (y
);
1961 if (TREE_CODE (expry
) == COMPONENT_REF
)
1963 tree t
= decl_for_component_ref (expry
);
1966 moffsety
= adjust_offset_for_component_ref (expry
, moffsety
);
1970 if (! DECL_P (exprx
) || ! DECL_P (expry
))
1973 rtlx
= DECL_RTL (exprx
);
1974 rtly
= DECL_RTL (expry
);
1976 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
1977 can't overlap unless they are the same because we never reuse that part
1978 of the stack frame used for locals for spilled pseudos. */
1979 if ((GET_CODE (rtlx
) != MEM
|| GET_CODE (rtly
) != MEM
)
1980 && ! rtx_equal_p (rtlx
, rtly
))
1983 /* Get the base and offsets of both decls. If either is a register, we
1984 know both are and are the same, so use that as the base. The only
1985 we can avoid overlap is if we can deduce that they are nonoverlapping
1986 pieces of that decl, which is very rare. */
1987 basex
= GET_CODE (rtlx
) == MEM
? XEXP (rtlx
, 0) : rtlx
;
1988 if (GET_CODE (basex
) == PLUS
&& GET_CODE (XEXP (basex
, 1)) == CONST_INT
)
1989 offsetx
= INTVAL (XEXP (basex
, 1)), basex
= XEXP (basex
, 0);
1991 basey
= GET_CODE (rtly
) == MEM
? XEXP (rtly
, 0) : rtly
;
1992 if (GET_CODE (basey
) == PLUS
&& GET_CODE (XEXP (basey
, 1)) == CONST_INT
)
1993 offsety
= INTVAL (XEXP (basey
, 1)), basey
= XEXP (basey
, 0);
1995 /* If the bases are different, we know they do not overlap if both
1996 are constants or if one is a constant and the other a pointer into the
1997 stack frame. Otherwise a different base means we can't tell if they
1999 if (! rtx_equal_p (basex
, basey
))
2000 return ((CONSTANT_P (basex
) && CONSTANT_P (basey
))
2001 || (CONSTANT_P (basex
) && REG_P (basey
)
2002 && REGNO_PTR_FRAME_P (REGNO (basey
)))
2003 || (CONSTANT_P (basey
) && REG_P (basex
)
2004 && REGNO_PTR_FRAME_P (REGNO (basex
))));
2006 sizex
= (GET_CODE (rtlx
) != MEM
? (int) GET_MODE_SIZE (GET_MODE (rtlx
))
2007 : MEM_SIZE (rtlx
) ? INTVAL (MEM_SIZE (rtlx
))
2009 sizey
= (GET_CODE (rtly
) != MEM
? (int) GET_MODE_SIZE (GET_MODE (rtly
))
2010 : MEM_SIZE (rtly
) ? INTVAL (MEM_SIZE (rtly
)) :
2013 /* If we have an offset for either memref, it can update the values computed
2016 offsetx
+= INTVAL (moffsetx
), sizex
-= INTVAL (moffsetx
);
2018 offsety
+= INTVAL (moffsety
), sizey
-= INTVAL (moffsety
);
2020 /* If a memref has both a size and an offset, we can use the smaller size.
2021 We can't do this if the offset isn't known because we must view this
2022 memref as being anywhere inside the DECL's MEM. */
2023 if (MEM_SIZE (x
) && moffsetx
)
2024 sizex
= INTVAL (MEM_SIZE (x
));
2025 if (MEM_SIZE (y
) && moffsety
)
2026 sizey
= INTVAL (MEM_SIZE (y
));
2028 /* Put the values of the memref with the lower offset in X's values. */
2029 if (offsetx
> offsety
)
2031 tem
= offsetx
, offsetx
= offsety
, offsety
= tem
;
2032 tem
= sizex
, sizex
= sizey
, sizey
= tem
;
2035 /* If we don't know the size of the lower-offset value, we can't tell
2036 if they conflict. Otherwise, we do the test. */
2037 return sizex
>= 0 && offsety
>= offsetx
+ sizex
;
2040 /* True dependence: X is read after store in MEM takes place. */
2043 true_dependence (mem
, mem_mode
, x
, varies
)
2045 enum machine_mode mem_mode
;
2047 int (*varies
) PARAMS ((rtx
, int));
2049 rtx x_addr
, mem_addr
;
2052 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2055 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2056 This is used in epilogue deallocation functions. */
2057 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2059 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2062 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
2065 /* Unchanging memory can't conflict with non-unchanging memory.
2066 A non-unchanging read can conflict with a non-unchanging write.
2067 An unchanging read can conflict with an unchanging write since
2068 there may be a single store to this address to initialize it.
2069 Note that an unchanging store can conflict with a non-unchanging read
2070 since we have to make conservative assumptions when we have a
2071 record with readonly fields and we are copying the whole thing.
2072 Just fall through to the code below to resolve potential conflicts.
2073 This won't handle all cases optimally, but the possible performance
2074 loss should be negligible. */
2075 if (RTX_UNCHANGING_P (x
) && ! RTX_UNCHANGING_P (mem
))
2078 if (nonoverlapping_memrefs_p (mem
, x
))
2081 if (mem_mode
== VOIDmode
)
2082 mem_mode
= GET_MODE (mem
);
2084 x_addr
= get_addr (XEXP (x
, 0));
2085 mem_addr
= get_addr (XEXP (mem
, 0));
2087 base
= find_base_term (x_addr
);
2088 if (base
&& (GET_CODE (base
) == LABEL_REF
2089 || (GET_CODE (base
) == SYMBOL_REF
2090 && CONSTANT_POOL_ADDRESS_P (base
))))
2093 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
), mem_mode
))
2096 x_addr
= canon_rtx (x_addr
);
2097 mem_addr
= canon_rtx (mem_addr
);
2099 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
2100 SIZE_FOR_MODE (x
), x_addr
, 0))
2103 if (aliases_everything_p (x
))
2106 /* We cannot use aliases_everything_p to test MEM, since we must look
2107 at MEM_MODE, rather than GET_MODE (MEM). */
2108 if (mem_mode
== QImode
|| GET_CODE (mem_addr
) == AND
)
2111 /* In true_dependence we also allow BLKmode to alias anything. Why
2112 don't we do this in anti_dependence and output_dependence? */
2113 if (mem_mode
== BLKmode
|| GET_MODE (x
) == BLKmode
)
2116 return ! fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
2120 /* Canonical true dependence: X is read after store in MEM takes place.
2121 Variant of true_dependence which assumes MEM has already been
2122 canonicalized (hence we no longer do that here).
2123 The mem_addr argument has been added, since true_dependence computed
2124 this value prior to canonicalizing. */
2127 canon_true_dependence (mem
, mem_mode
, mem_addr
, x
, varies
)
2128 rtx mem
, mem_addr
, x
;
2129 enum machine_mode mem_mode
;
2130 int (*varies
) PARAMS ((rtx
, int));
2134 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2137 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2138 This is used in epilogue deallocation functions. */
2139 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2141 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2144 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
2147 /* If X is an unchanging read, then it can't possibly conflict with any
2148 non-unchanging store. It may conflict with an unchanging write though,
2149 because there may be a single store to this address to initialize it.
2150 Just fall through to the code below to resolve the case where we have
2151 both an unchanging read and an unchanging write. This won't handle all
2152 cases optimally, but the possible performance loss should be
2154 if (RTX_UNCHANGING_P (x
) && ! RTX_UNCHANGING_P (mem
))
2157 if (nonoverlapping_memrefs_p (x
, mem
))
2160 x_addr
= get_addr (XEXP (x
, 0));
2162 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
), mem_mode
))
2165 x_addr
= canon_rtx (x_addr
);
2166 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
2167 SIZE_FOR_MODE (x
), x_addr
, 0))
2170 if (aliases_everything_p (x
))
2173 /* We cannot use aliases_everything_p to test MEM, since we must look
2174 at MEM_MODE, rather than GET_MODE (MEM). */
2175 if (mem_mode
== QImode
|| GET_CODE (mem_addr
) == AND
)
2178 /* In true_dependence we also allow BLKmode to alias anything. Why
2179 don't we do this in anti_dependence and output_dependence? */
2180 if (mem_mode
== BLKmode
|| GET_MODE (x
) == BLKmode
)
2183 return ! fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
2187 /* Returns non-zero if a write to X might alias a previous read from
2188 (or, if WRITEP is non-zero, a write to) MEM. */
2191 write_dependence_p (mem
, x
, writep
)
2196 rtx x_addr
, mem_addr
;
2200 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2203 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2204 This is used in epilogue deallocation functions. */
2205 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2207 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2210 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
2213 /* Unchanging memory can't conflict with non-unchanging memory. */
2214 if (RTX_UNCHANGING_P (x
) != RTX_UNCHANGING_P (mem
))
2217 /* If MEM is an unchanging read, then it can't possibly conflict with
2218 the store to X, because there is at most one store to MEM, and it must
2219 have occurred somewhere before MEM. */
2220 if (! writep
&& RTX_UNCHANGING_P (mem
))
2223 if (nonoverlapping_memrefs_p (x
, mem
))
2226 x_addr
= get_addr (XEXP (x
, 0));
2227 mem_addr
= get_addr (XEXP (mem
, 0));
2231 base
= find_base_term (mem_addr
);
2232 if (base
&& (GET_CODE (base
) == LABEL_REF
2233 || (GET_CODE (base
) == SYMBOL_REF
2234 && CONSTANT_POOL_ADDRESS_P (base
))))
2238 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
),
2242 x_addr
= canon_rtx (x_addr
);
2243 mem_addr
= canon_rtx (mem_addr
);
2245 if (!memrefs_conflict_p (SIZE_FOR_MODE (mem
), mem_addr
,
2246 SIZE_FOR_MODE (x
), x_addr
, 0))
2250 = fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
2253 return (!(fixed_scalar
== mem
&& !aliases_everything_p (x
))
2254 && !(fixed_scalar
== x
&& !aliases_everything_p (mem
)));
2257 /* Anti dependence: X is written after read in MEM takes place. */
2260 anti_dependence (mem
, x
)
2264 return write_dependence_p (mem
, x
, /*writep=*/0);
2267 /* Output dependence: X is written after store in MEM takes place. */
2270 output_dependence (mem
, x
)
2274 return write_dependence_p (mem
, x
, /*writep=*/1);
2277 /* A subroutine of nonlocal_mentioned_p, returns 1 if *LOC mentions
2278 something which is not local to the function and is not constant. */
2281 nonlocal_mentioned_p_1 (loc
, data
)
2283 void *data ATTRIBUTE_UNUSED
;
2292 switch (GET_CODE (x
))
2295 if (GET_CODE (SUBREG_REG (x
)) == REG
)
2297 /* Global registers are not local. */
2298 if (REGNO (SUBREG_REG (x
)) < FIRST_PSEUDO_REGISTER
2299 && global_regs
[subreg_regno (x
)])
2307 /* Global registers are not local. */
2308 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2323 /* Constants in the function's constants pool are constant. */
2324 if (CONSTANT_POOL_ADDRESS_P (x
))
2329 /* Non-constant calls and recursion are not local. */
2333 /* Be overly conservative and consider any volatile memory
2334 reference as not local. */
2335 if (MEM_VOLATILE_P (x
))
2337 base
= find_base_term (XEXP (x
, 0));
2340 /* A Pmode ADDRESS could be a reference via the structure value
2341 address or static chain. Such memory references are nonlocal.
2343 Thus, we have to examine the contents of the ADDRESS to find
2344 out if this is a local reference or not. */
2345 if (GET_CODE (base
) == ADDRESS
2346 && GET_MODE (base
) == Pmode
2347 && (XEXP (base
, 0) == stack_pointer_rtx
2348 || XEXP (base
, 0) == arg_pointer_rtx
2349 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2350 || XEXP (base
, 0) == hard_frame_pointer_rtx
2352 || XEXP (base
, 0) == frame_pointer_rtx
))
2354 /* Constants in the function's constant pool are constant. */
2355 if (GET_CODE (base
) == SYMBOL_REF
&& CONSTANT_POOL_ADDRESS_P (base
))
2360 case UNSPEC_VOLATILE
:
2365 if (MEM_VOLATILE_P (x
))
2377 /* Returns non-zero if X might mention something which is not
2378 local to the function and is not constant. */
2381 nonlocal_mentioned_p (x
)
2387 if (GET_CODE (x
) == CALL_INSN
)
2389 if (! CONST_OR_PURE_CALL_P (x
))
2391 x
= CALL_INSN_FUNCTION_USAGE (x
);
2399 return for_each_rtx (&x
, nonlocal_mentioned_p_1
, NULL
);
2402 /* A subroutine of nonlocal_referenced_p, returns 1 if *LOC references
2403 something which is not local to the function and is not constant. */
2406 nonlocal_referenced_p_1 (loc
, data
)
2408 void *data ATTRIBUTE_UNUSED
;
2415 switch (GET_CODE (x
))
2421 return nonlocal_mentioned_p (x
);
2424 /* Non-constant calls and recursion are not local. */
2428 if (nonlocal_mentioned_p (SET_SRC (x
)))
2431 if (GET_CODE (SET_DEST (x
)) == MEM
)
2432 return nonlocal_mentioned_p (XEXP (SET_DEST (x
), 0));
2434 /* If the destination is anything other than a CC0, PC,
2435 MEM, REG, or a SUBREG of a REG that occupies all of
2436 the REG, then X references nonlocal memory if it is
2437 mentioned in the destination. */
2438 if (GET_CODE (SET_DEST (x
)) != CC0
2439 && GET_CODE (SET_DEST (x
)) != PC
2440 && GET_CODE (SET_DEST (x
)) != REG
2441 && ! (GET_CODE (SET_DEST (x
)) == SUBREG
2442 && GET_CODE (SUBREG_REG (SET_DEST (x
))) == REG
2443 && (((GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (x
))))
2444 + (UNITS_PER_WORD
- 1)) / UNITS_PER_WORD
)
2445 == ((GET_MODE_SIZE (GET_MODE (SET_DEST (x
)))
2446 + (UNITS_PER_WORD
- 1)) / UNITS_PER_WORD
))))
2447 return nonlocal_mentioned_p (SET_DEST (x
));
2451 if (GET_CODE (XEXP (x
, 0)) == MEM
)
2452 return nonlocal_mentioned_p (XEXP (XEXP (x
, 0), 0));
2456 return nonlocal_mentioned_p (XEXP (x
, 0));
2459 case UNSPEC_VOLATILE
:
2463 if (MEM_VOLATILE_P (x
))
2475 /* Returns non-zero if X might reference something which is not
2476 local to the function and is not constant. */
2479 nonlocal_referenced_p (x
)
2485 if (GET_CODE (x
) == CALL_INSN
)
2487 if (! CONST_OR_PURE_CALL_P (x
))
2489 x
= CALL_INSN_FUNCTION_USAGE (x
);
2497 return for_each_rtx (&x
, nonlocal_referenced_p_1
, NULL
);
2500 /* A subroutine of nonlocal_set_p, returns 1 if *LOC sets
2501 something which is not local to the function and is not constant. */
2504 nonlocal_set_p_1 (loc
, data
)
2506 void *data ATTRIBUTE_UNUSED
;
2513 switch (GET_CODE (x
))
2516 /* Non-constant calls and recursion are not local. */
2525 return nonlocal_mentioned_p (XEXP (x
, 0));
2528 if (nonlocal_mentioned_p (SET_DEST (x
)))
2530 return nonlocal_set_p (SET_SRC (x
));
2533 return nonlocal_mentioned_p (XEXP (x
, 0));
2539 case UNSPEC_VOLATILE
:
2543 if (MEM_VOLATILE_P (x
))
2555 /* Returns non-zero if X might set something which is not
2556 local to the function and is not constant. */
2565 if (GET_CODE (x
) == CALL_INSN
)
2567 if (! CONST_OR_PURE_CALL_P (x
))
2569 x
= CALL_INSN_FUNCTION_USAGE (x
);
2577 return for_each_rtx (&x
, nonlocal_set_p_1
, NULL
);
2580 /* Mark the function if it is constant. */
2583 mark_constant_function ()
2586 int nonlocal_memory_referenced
;
2588 if (TREE_READONLY (current_function_decl
)
2589 || DECL_IS_PURE (current_function_decl
)
2590 || TREE_THIS_VOLATILE (current_function_decl
)
2591 || TYPE_MODE (TREE_TYPE (current_function_decl
)) == VOIDmode
2592 || current_function_has_nonlocal_goto
2593 || !(*targetm
.binds_local_p
) (current_function_decl
))
2596 /* A loop might not return which counts as a side effect. */
2597 if (mark_dfs_back_edges ())
2600 nonlocal_memory_referenced
= 0;
2602 init_alias_analysis ();
2604 /* Determine if this is a constant or pure function. */
2606 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
2608 if (! INSN_P (insn
))
2611 if (nonlocal_set_p (insn
) || global_reg_mentioned_p (insn
)
2612 || volatile_refs_p (PATTERN (insn
)))
2615 if (! nonlocal_memory_referenced
)
2616 nonlocal_memory_referenced
= nonlocal_referenced_p (insn
);
2619 end_alias_analysis ();
2621 /* Mark the function. */
2625 else if (nonlocal_memory_referenced
)
2626 DECL_IS_PURE (current_function_decl
) = 1;
2628 TREE_READONLY (current_function_decl
) = 1;
2637 #ifndef OUTGOING_REGNO
2638 #define OUTGOING_REGNO(N) N
2640 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2641 /* Check whether this register can hold an incoming pointer
2642 argument. FUNCTION_ARG_REGNO_P tests outgoing register
2643 numbers, so translate if necessary due to register windows. */
2644 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i
))
2645 && HARD_REGNO_MODE_OK (i
, Pmode
))
2646 static_reg_base_value
[i
]
2647 = gen_rtx_ADDRESS (VOIDmode
, gen_rtx_REG (Pmode
, i
));
2649 static_reg_base_value
[STACK_POINTER_REGNUM
]
2650 = gen_rtx_ADDRESS (Pmode
, stack_pointer_rtx
);
2651 static_reg_base_value
[ARG_POINTER_REGNUM
]
2652 = gen_rtx_ADDRESS (Pmode
, arg_pointer_rtx
);
2653 static_reg_base_value
[FRAME_POINTER_REGNUM
]
2654 = gen_rtx_ADDRESS (Pmode
, frame_pointer_rtx
);
2655 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2656 static_reg_base_value
[HARD_FRAME_POINTER_REGNUM
]
2657 = gen_rtx_ADDRESS (Pmode
, hard_frame_pointer_rtx
);
2660 alias_sets
= splay_tree_new (splay_tree_compare_ints
, 0, 0);
2663 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
2667 init_alias_analysis ()
2669 int maxreg
= max_reg_num ();
2675 reg_known_value_size
= maxreg
;
2678 = (rtx
*) xcalloc ((maxreg
- FIRST_PSEUDO_REGISTER
), sizeof (rtx
))
2679 - FIRST_PSEUDO_REGISTER
;
2681 = (char*) xcalloc ((maxreg
- FIRST_PSEUDO_REGISTER
), sizeof (char))
2682 - FIRST_PSEUDO_REGISTER
;
2684 /* Overallocate reg_base_value to allow some growth during loop
2685 optimization. Loop unrolling can create a large number of
2687 reg_base_value_size
= maxreg
* 2;
2688 reg_base_value
= (rtx
*) ggc_alloc_cleared (reg_base_value_size
2691 new_reg_base_value
= (rtx
*) xmalloc (reg_base_value_size
* sizeof (rtx
));
2692 reg_seen
= (char *) xmalloc (reg_base_value_size
);
2693 if (! reload_completed
&& flag_unroll_loops
)
2695 /* ??? Why are we realloc'ing if we're just going to zero it? */
2696 alias_invariant
= (rtx
*)xrealloc (alias_invariant
,
2697 reg_base_value_size
* sizeof (rtx
));
2698 memset ((char *)alias_invariant
, 0, reg_base_value_size
* sizeof (rtx
));
2701 /* The basic idea is that each pass through this loop will use the
2702 "constant" information from the previous pass to propagate alias
2703 information through another level of assignments.
2705 This could get expensive if the assignment chains are long. Maybe
2706 we should throttle the number of iterations, possibly based on
2707 the optimization level or flag_expensive_optimizations.
2709 We could propagate more information in the first pass by making use
2710 of REG_N_SETS to determine immediately that the alias information
2711 for a pseudo is "constant".
2713 A program with an uninitialized variable can cause an infinite loop
2714 here. Instead of doing a full dataflow analysis to detect such problems
2715 we just cap the number of iterations for the loop.
2717 The state of the arrays for the set chain in question does not matter
2718 since the program has undefined behavior. */
2723 /* Assume nothing will change this iteration of the loop. */
2726 /* We want to assign the same IDs each iteration of this loop, so
2727 start counting from zero each iteration of the loop. */
2730 /* We're at the start of the function each iteration through the
2731 loop, so we're copying arguments. */
2732 copying_arguments
= 1;
2734 /* Wipe the potential alias information clean for this pass. */
2735 memset ((char *) new_reg_base_value
, 0, reg_base_value_size
* sizeof (rtx
));
2737 /* Wipe the reg_seen array clean. */
2738 memset ((char *) reg_seen
, 0, reg_base_value_size
);
2740 /* Mark all hard registers which may contain an address.
2741 The stack, frame and argument pointers may contain an address.
2742 An argument register which can hold a Pmode value may contain
2743 an address even if it is not in BASE_REGS.
2745 The address expression is VOIDmode for an argument and
2746 Pmode for other registers. */
2748 memcpy (new_reg_base_value
, static_reg_base_value
,
2749 FIRST_PSEUDO_REGISTER
* sizeof (rtx
));
2751 /* Walk the insns adding values to the new_reg_base_value array. */
2752 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
2758 #if defined (HAVE_prologue) || defined (HAVE_epilogue)
2759 /* The prologue/epilogue insns are not threaded onto the
2760 insn chain until after reload has completed. Thus,
2761 there is no sense wasting time checking if INSN is in
2762 the prologue/epilogue until after reload has completed. */
2763 if (reload_completed
2764 && prologue_epilogue_contains (insn
))
2768 /* If this insn has a noalias note, process it, Otherwise,
2769 scan for sets. A simple set will have no side effects
2770 which could change the base value of any other register. */
2772 if (GET_CODE (PATTERN (insn
)) == SET
2773 && REG_NOTES (insn
) != 0
2774 && find_reg_note (insn
, REG_NOALIAS
, NULL_RTX
))
2775 record_set (SET_DEST (PATTERN (insn
)), NULL_RTX
, NULL
);
2777 note_stores (PATTERN (insn
), record_set
, NULL
);
2779 set
= single_set (insn
);
2782 && GET_CODE (SET_DEST (set
)) == REG
2783 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
)
2785 unsigned int regno
= REGNO (SET_DEST (set
));
2786 rtx src
= SET_SRC (set
);
2788 if (REG_NOTES (insn
) != 0
2789 && (((note
= find_reg_note (insn
, REG_EQUAL
, 0)) != 0
2790 && REG_N_SETS (regno
) == 1)
2791 || (note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) != 0)
2792 && GET_CODE (XEXP (note
, 0)) != EXPR_LIST
2793 && ! rtx_varies_p (XEXP (note
, 0), 1)
2794 && ! reg_overlap_mentioned_p (SET_DEST (set
), XEXP (note
, 0)))
2796 reg_known_value
[regno
] = XEXP (note
, 0);
2797 reg_known_equiv_p
[regno
] = REG_NOTE_KIND (note
) == REG_EQUIV
;
2799 else if (REG_N_SETS (regno
) == 1
2800 && GET_CODE (src
) == PLUS
2801 && GET_CODE (XEXP (src
, 0)) == REG
2802 && REGNO (XEXP (src
, 0)) >= FIRST_PSEUDO_REGISTER
2803 && (reg_known_value
[REGNO (XEXP (src
, 0))])
2804 && GET_CODE (XEXP (src
, 1)) == CONST_INT
)
2806 rtx op0
= XEXP (src
, 0);
2807 op0
= reg_known_value
[REGNO (op0
)];
2808 reg_known_value
[regno
]
2809 = plus_constant (op0
, INTVAL (XEXP (src
, 1)));
2810 reg_known_equiv_p
[regno
] = 0;
2812 else if (REG_N_SETS (regno
) == 1
2813 && ! rtx_varies_p (src
, 1))
2815 reg_known_value
[regno
] = src
;
2816 reg_known_equiv_p
[regno
] = 0;
2820 else if (GET_CODE (insn
) == NOTE
2821 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_BEG
)
2822 copying_arguments
= 0;
2825 /* Now propagate values from new_reg_base_value to reg_base_value. */
2826 for (ui
= 0; ui
< reg_base_value_size
; ui
++)
2828 if (new_reg_base_value
[ui
]
2829 && new_reg_base_value
[ui
] != reg_base_value
[ui
]
2830 && ! rtx_equal_p (new_reg_base_value
[ui
], reg_base_value
[ui
]))
2832 reg_base_value
[ui
] = new_reg_base_value
[ui
];
2837 while (changed
&& ++pass
< MAX_ALIAS_LOOP_PASSES
);
2839 /* Fill in the remaining entries. */
2840 for (i
= FIRST_PSEUDO_REGISTER
; i
< maxreg
; i
++)
2841 if (reg_known_value
[i
] == 0)
2842 reg_known_value
[i
] = regno_reg_rtx
[i
];
2844 /* Simplify the reg_base_value array so that no register refers to
2845 another register, except to special registers indirectly through
2846 ADDRESS expressions.
2848 In theory this loop can take as long as O(registers^2), but unless
2849 there are very long dependency chains it will run in close to linear
2852 This loop may not be needed any longer now that the main loop does
2853 a better job at propagating alias information. */
2859 for (ui
= 0; ui
< reg_base_value_size
; ui
++)
2861 rtx base
= reg_base_value
[ui
];
2862 if (base
&& GET_CODE (base
) == REG
)
2864 unsigned int base_regno
= REGNO (base
);
2865 if (base_regno
== ui
) /* register set from itself */
2866 reg_base_value
[ui
] = 0;
2868 reg_base_value
[ui
] = reg_base_value
[base_regno
];
2873 while (changed
&& pass
< MAX_ALIAS_LOOP_PASSES
);
2876 free (new_reg_base_value
);
2877 new_reg_base_value
= 0;
2883 end_alias_analysis ()
2885 free (reg_known_value
+ FIRST_PSEUDO_REGISTER
);
2886 reg_known_value
= 0;
2887 reg_known_value_size
= 0;
2888 free (reg_known_equiv_p
+ FIRST_PSEUDO_REGISTER
);
2889 reg_known_equiv_p
= 0;
2891 reg_base_value_size
= 0;
2892 if (alias_invariant
)
2894 free (alias_invariant
);
2895 alias_invariant
= 0;
2899 #include "gt-alias.h"