1 /* Alias analysis for GNU C
2 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
3 Free Software Foundation, Inc.
4 Contributed by John Carr (jfc@mit.edu).
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to the Free
20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
25 #include "coretypes.h"
34 #include "hard-reg-set.h"
35 #include "basic-block.h"
40 #include "splay-tree.h"
42 #include "langhooks.h"
48 /* The alias sets assigned to MEMs assist the back-end in determining
49 which MEMs can alias which other MEMs. In general, two MEMs in
50 different alias sets cannot alias each other, with one important
51 exception. Consider something like:
53 struct S { int i; double d; };
55 a store to an `S' can alias something of either type `int' or type
56 `double'. (However, a store to an `int' cannot alias a `double'
57 and vice versa.) We indicate this via a tree structure that looks
65 (The arrows are directed and point downwards.)
66 In this situation we say the alias set for `struct S' is the
67 `superset' and that those for `int' and `double' are `subsets'.
69 To see whether two alias sets can point to the same memory, we must
70 see if either alias set is a subset of the other. We need not trace
71 past immediate descendants, however, since we propagate all
72 grandchildren up one level.
74 Alias set zero is implicitly a superset of all other alias sets.
75 However, this is no actual entry for alias set zero. It is an
76 error to attempt to explicitly construct a subset of zero. */
78 struct alias_set_entry
GTY(())
80 /* The alias set number, as stored in MEM_ALIAS_SET. */
81 HOST_WIDE_INT alias_set
;
83 /* The children of the alias set. These are not just the immediate
84 children, but, in fact, all descendants. So, if we have:
86 struct T { struct S s; float f; }
88 continuing our example above, the children here will be all of
89 `int', `double', `float', and `struct S'. */
90 splay_tree
GTY((param1_is (int), param2_is (int))) children
;
92 /* Nonzero if would have a child of zero: this effectively makes this
93 alias set the same as alias set zero. */
96 typedef struct alias_set_entry
*alias_set_entry
;
98 static int rtx_equal_for_memref_p (rtx
, rtx
);
99 static rtx
find_symbolic_term (rtx
);
100 static int memrefs_conflict_p (int, rtx
, int, rtx
, HOST_WIDE_INT
);
101 static void record_set (rtx
, rtx
, void *);
102 static int base_alias_check (rtx
, rtx
, enum machine_mode
,
104 static rtx
find_base_value (rtx
);
105 static int mems_in_disjoint_alias_sets_p (rtx
, rtx
);
106 static int insert_subset_children (splay_tree_node
, void*);
107 static tree
find_base_decl (tree
);
108 static alias_set_entry
get_alias_set_entry (HOST_WIDE_INT
);
109 static rtx
fixed_scalar_and_varying_struct_p (rtx
, rtx
, rtx
, rtx
,
111 static int aliases_everything_p (rtx
);
112 static bool nonoverlapping_component_refs_p (tree
, tree
);
113 static tree
decl_for_component_ref (tree
);
114 static rtx
adjust_offset_for_component_ref (tree
, rtx
);
115 static int nonoverlapping_memrefs_p (rtx
, rtx
);
116 static int write_dependence_p (rtx
, rtx
, int);
118 static int nonlocal_mentioned_p_1 (rtx
*, void *);
119 static int nonlocal_mentioned_p (rtx
);
120 static int nonlocal_referenced_p_1 (rtx
*, void *);
121 static int nonlocal_referenced_p (rtx
);
122 static int nonlocal_set_p_1 (rtx
*, void *);
123 static int nonlocal_set_p (rtx
);
124 static void memory_modified_1 (rtx
, rtx
, void *);
125 static void record_alias_subset (HOST_WIDE_INT
, HOST_WIDE_INT
);
127 /* Set up all info needed to perform alias analysis on memory references. */
129 /* Returns the size in bytes of the mode of X. */
130 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
132 /* Returns nonzero if MEM1 and MEM2 do not alias because they are in
133 different alias sets. We ignore alias sets in functions making use
134 of variable arguments because the va_arg macros on some systems are
136 #define DIFFERENT_ALIAS_SETS_P(MEM1, MEM2) \
137 mems_in_disjoint_alias_sets_p (MEM1, MEM2)
139 /* Cap the number of passes we make over the insns propagating alias
140 information through set chains. 10 is a completely arbitrary choice. */
141 #define MAX_ALIAS_LOOP_PASSES 10
143 /* reg_base_value[N] gives an address to which register N is related.
144 If all sets after the first add or subtract to the current value
145 or otherwise modify it so it does not point to a different top level
146 object, reg_base_value[N] is equal to the address part of the source
149 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
150 expressions represent certain special values: function arguments and
151 the stack, frame, and argument pointers.
153 The contents of an ADDRESS is not normally used, the mode of the
154 ADDRESS determines whether the ADDRESS is a function argument or some
155 other special value. Pointer equality, not rtx_equal_p, determines whether
156 two ADDRESS expressions refer to the same base address.
158 The only use of the contents of an ADDRESS is for determining if the
159 current function performs nonlocal memory memory references for the
160 purposes of marking the function as a constant function. */
162 static GTY(()) varray_type reg_base_value
;
163 static rtx
*new_reg_base_value
;
165 /* We preserve the copy of old array around to avoid amount of garbage
166 produced. About 8% of garbage produced were attributed to this
168 static GTY((deletable
)) varray_type old_reg_base_value
;
170 /* Static hunks of RTL used by the aliasing code; these are initialized
171 once per function to avoid unnecessary RTL allocations. */
172 static GTY (()) rtx static_reg_base_value
[FIRST_PSEUDO_REGISTER
];
174 #define REG_BASE_VALUE(X) \
175 (reg_base_value && REGNO (X) < VARRAY_SIZE (reg_base_value) \
176 ? VARRAY_RTX (reg_base_value, REGNO (X)) : 0)
178 /* Vector of known invariant relationships between registers. Set in
179 loop unrolling. Indexed by register number, if nonzero the value
180 is an expression describing this register in terms of another.
182 The length of this array is REG_BASE_VALUE_SIZE.
184 Because this array contains only pseudo registers it has no effect
186 static GTY((length("alias_invariant_size"))) rtx
*alias_invariant
;
187 static GTY(()) unsigned int alias_invariant_size
;
189 /* Vector indexed by N giving the initial (unchanging) value known for
190 pseudo-register N. This array is initialized in init_alias_analysis,
191 and does not change until end_alias_analysis is called. */
192 static GTY((length("reg_known_value_size"))) rtx
*reg_known_value
;
194 /* Indicates number of valid entries in reg_known_value. */
195 static GTY(()) unsigned int reg_known_value_size
;
197 /* Vector recording for each reg_known_value whether it is due to a
198 REG_EQUIV note. Future passes (viz., reload) may replace the
199 pseudo with the equivalent expression and so we account for the
200 dependences that would be introduced if that happens.
202 The REG_EQUIV notes created in assign_parms may mention the arg
203 pointer, and there are explicit insns in the RTL that modify the
204 arg pointer. Thus we must ensure that such insns don't get
205 scheduled across each other because that would invalidate the
206 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
207 wrong, but solving the problem in the scheduler will likely give
208 better code, so we do it here. */
209 static bool *reg_known_equiv_p
;
211 /* True when scanning insns from the start of the rtl to the
212 NOTE_INSN_FUNCTION_BEG note. */
213 static bool copying_arguments
;
215 /* The splay-tree used to store the various alias set entries. */
216 static GTY ((param_is (struct alias_set_entry
))) varray_type alias_sets
;
218 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
219 such an entry, or NULL otherwise. */
221 static inline alias_set_entry
222 get_alias_set_entry (HOST_WIDE_INT alias_set
)
224 return (alias_set_entry
)VARRAY_GENERIC_PTR (alias_sets
, alias_set
);
227 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
228 the two MEMs cannot alias each other. */
231 mems_in_disjoint_alias_sets_p (rtx mem1
, rtx mem2
)
233 /* Perform a basic sanity check. Namely, that there are no alias sets
234 if we're not using strict aliasing. This helps to catch bugs
235 whereby someone uses PUT_CODE, but doesn't clear MEM_ALIAS_SET, or
236 where a MEM is allocated in some way other than by the use of
237 gen_rtx_MEM, and the MEM_ALIAS_SET is not cleared. If we begin to
238 use alias sets to indicate that spilled registers cannot alias each
239 other, we might need to remove this check. */
240 gcc_assert (flag_strict_aliasing
241 || (!MEM_ALIAS_SET (mem1
) && !MEM_ALIAS_SET (mem2
)));
243 return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1
), MEM_ALIAS_SET (mem2
));
246 /* Insert the NODE into the splay tree given by DATA. Used by
247 record_alias_subset via splay_tree_foreach. */
250 insert_subset_children (splay_tree_node node
, void *data
)
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 (HOST_WIDE_INT set1
, HOST_WIDE_INT set2
)
264 /* If have no alias set information for one of the operands, we have
265 to assume it can alias anything. */
266 if (set1
== 0 || set2
== 0
267 /* If the two alias sets are the same, they may alias. */
271 /* See if the first alias set is a subset of the second. */
272 ase
= get_alias_set_entry (set1
);
274 && (ase
->has_zero_child
275 || splay_tree_lookup (ase
->children
,
276 (splay_tree_key
) set2
)))
279 /* Now do the same, but with the alias sets reversed. */
280 ase
= get_alias_set_entry (set2
);
282 && (ase
->has_zero_child
283 || splay_tree_lookup (ase
->children
,
284 (splay_tree_key
) set1
)))
287 /* The two alias sets are distinct and neither one is the
288 child of the other. Therefore, they cannot alias. */
292 /* Return 1 if the two specified alias sets might conflict, or if any subtype
293 of these alias sets might conflict. */
296 alias_sets_might_conflict_p (HOST_WIDE_INT set1
, HOST_WIDE_INT set2
)
298 if (set1
== 0 || set2
== 0 || set1
== set2
)
305 /* Return 1 if any MEM object of type T1 will always conflict (using the
306 dependency routines in this file) with any MEM object of type T2.
307 This is used when allocating temporary storage. If T1 and/or T2 are
308 NULL_TREE, it means we know nothing about the storage. */
311 objects_must_conflict_p (tree t1
, tree t2
)
313 HOST_WIDE_INT set1
, set2
;
315 /* If neither has a type specified, we don't know if they'll conflict
316 because we may be using them to store objects of various types, for
317 example the argument and local variables areas of inlined functions. */
318 if (t1
== 0 && t2
== 0)
321 /* If they are the same type, they must conflict. */
323 /* Likewise if both are volatile. */
324 || (t1
!= 0 && TYPE_VOLATILE (t1
) && t2
!= 0 && TYPE_VOLATILE (t2
)))
327 set1
= t1
? get_alias_set (t1
) : 0;
328 set2
= t2
? get_alias_set (t2
) : 0;
330 /* Otherwise they conflict if they have no alias set or the same. We
331 can't simply use alias_sets_conflict_p here, because we must make
332 sure that every subtype of t1 will conflict with every subtype of
333 t2 for which a pair of subobjects of these respective subtypes
334 overlaps on the stack. */
335 return set1
== 0 || set2
== 0 || set1
== set2
;
338 /* T is an expression with pointer type. Find the DECL on which this
339 expression is based. (For example, in `a[i]' this would be `a'.)
340 If there is no such DECL, or a unique decl cannot be determined,
341 NULL_TREE is returned. */
344 find_base_decl (tree t
)
348 if (t
== 0 || t
== error_mark_node
|| ! POINTER_TYPE_P (TREE_TYPE (t
)))
351 /* If this is a declaration, return it. */
355 /* Handle general expressions. It would be nice to deal with
356 COMPONENT_REFs here. If we could tell that `a' and `b' were the
357 same, then `a->f' and `b->f' are also the same. */
358 switch (TREE_CODE_CLASS (TREE_CODE (t
)))
361 return find_base_decl (TREE_OPERAND (t
, 0));
364 /* Return 0 if found in neither or both are the same. */
365 d0
= find_base_decl (TREE_OPERAND (t
, 0));
366 d1
= find_base_decl (TREE_OPERAND (t
, 1));
381 /* Return 1 if all the nested component references handled by
382 get_inner_reference in T are such that we can address the object in T. */
385 can_address_p (tree t
)
387 /* If we're at the end, it is vacuously addressable. */
388 if (! handled_component_p (t
))
391 /* Bitfields are never addressable. */
392 else if (TREE_CODE (t
) == BIT_FIELD_REF
)
395 /* Fields are addressable unless they are marked as nonaddressable or
396 the containing type has alias set 0. */
397 else if (TREE_CODE (t
) == COMPONENT_REF
398 && ! DECL_NONADDRESSABLE_P (TREE_OPERAND (t
, 1))
399 && get_alias_set (TREE_TYPE (TREE_OPERAND (t
, 0))) != 0
400 && can_address_p (TREE_OPERAND (t
, 0)))
403 /* Likewise for arrays. */
404 else if ((TREE_CODE (t
) == ARRAY_REF
|| TREE_CODE (t
) == ARRAY_RANGE_REF
)
405 && ! TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t
, 0)))
406 && get_alias_set (TREE_TYPE (TREE_OPERAND (t
, 0))) != 0
407 && can_address_p (TREE_OPERAND (t
, 0)))
413 /* Return the alias set for T, which may be either a type or an
414 expression. Call language-specific routine for help, if needed. */
417 get_alias_set (tree t
)
421 /* If we're not doing any alias analysis, just assume everything
422 aliases everything else. Also return 0 if this or its type is
424 if (! flag_strict_aliasing
|| t
== error_mark_node
426 && (TREE_TYPE (t
) == 0 || TREE_TYPE (t
) == error_mark_node
)))
429 /* We can be passed either an expression or a type. This and the
430 language-specific routine may make mutually-recursive calls to each other
431 to figure out what to do. At each juncture, we see if this is a tree
432 that the language may need to handle specially. First handle things that
438 /* Remove any nops, then give the language a chance to do
439 something with this tree before we look at it. */
441 set
= lang_hooks
.get_alias_set (t
);
445 /* First see if the actual object referenced is an INDIRECT_REF from a
446 restrict-qualified pointer or a "void *". */
447 while (handled_component_p (inner
))
449 inner
= TREE_OPERAND (inner
, 0);
453 /* Check for accesses through restrict-qualified pointers. */
454 if (INDIRECT_REF_P (inner
))
456 tree decl
= find_base_decl (TREE_OPERAND (inner
, 0));
458 if (decl
&& DECL_POINTER_ALIAS_SET_KNOWN_P (decl
))
460 /* If we haven't computed the actual alias set, do it now. */
461 if (DECL_POINTER_ALIAS_SET (decl
) == -2)
463 tree pointed_to_type
= TREE_TYPE (TREE_TYPE (decl
));
465 /* No two restricted pointers can point at the same thing.
466 However, a restricted pointer can point at the same thing
467 as an unrestricted pointer, if that unrestricted pointer
468 is based on the restricted pointer. So, we make the
469 alias set for the restricted pointer a subset of the
470 alias set for the type pointed to by the type of the
472 HOST_WIDE_INT pointed_to_alias_set
473 = get_alias_set (pointed_to_type
);
475 if (pointed_to_alias_set
== 0)
476 /* It's not legal to make a subset of alias set zero. */
477 DECL_POINTER_ALIAS_SET (decl
) = 0;
478 else if (AGGREGATE_TYPE_P (pointed_to_type
))
479 /* For an aggregate, we must treat the restricted
480 pointer the same as an ordinary pointer. If we
481 were to make the type pointed to by the
482 restricted pointer a subset of the pointed-to
483 type, then we would believe that other subsets
484 of the pointed-to type (such as fields of that
485 type) do not conflict with the type pointed to
486 by the restricted pointer. */
487 DECL_POINTER_ALIAS_SET (decl
)
488 = pointed_to_alias_set
;
491 DECL_POINTER_ALIAS_SET (decl
) = new_alias_set ();
492 record_alias_subset (pointed_to_alias_set
,
493 DECL_POINTER_ALIAS_SET (decl
));
497 /* We use the alias set indicated in the declaration. */
498 return DECL_POINTER_ALIAS_SET (decl
);
501 /* If we have an INDIRECT_REF via a void pointer, we don't
502 know anything about what that might alias. Likewise if the
503 pointer is marked that way. */
504 else if (TREE_CODE (TREE_TYPE (inner
)) == VOID_TYPE
505 || (TYPE_REF_CAN_ALIAS_ALL
506 (TREE_TYPE (TREE_OPERAND (inner
, 0)))))
510 /* Otherwise, pick up the outermost object that we could have a pointer
511 to, processing conversions as above. */
512 while (handled_component_p (t
) && ! can_address_p (t
))
514 t
= TREE_OPERAND (t
, 0);
518 /* If we've already determined the alias set for a decl, just return
519 it. This is necessary for C++ anonymous unions, whose component
520 variables don't look like union members (boo!). */
521 if (TREE_CODE (t
) == VAR_DECL
522 && DECL_RTL_SET_P (t
) && MEM_P (DECL_RTL (t
)))
523 return MEM_ALIAS_SET (DECL_RTL (t
));
525 /* Now all we care about is the type. */
529 /* Variant qualifiers don't affect the alias set, so get the main
530 variant. If this is a type with a known alias set, return it. */
531 t
= TYPE_MAIN_VARIANT (t
);
532 if (TYPE_ALIAS_SET_KNOWN_P (t
))
533 return TYPE_ALIAS_SET (t
);
535 /* See if the language has special handling for this type. */
536 set
= lang_hooks
.get_alias_set (t
);
540 /* There are no objects of FUNCTION_TYPE, so there's no point in
541 using up an alias set for them. (There are, of course, pointers
542 and references to functions, but that's different.) */
543 else if (TREE_CODE (t
) == FUNCTION_TYPE
)
546 /* Unless the language specifies otherwise, let vector types alias
547 their components. This avoids some nasty type punning issues in
548 normal usage. And indeed lets vectors be treated more like an
550 else if (TREE_CODE (t
) == VECTOR_TYPE
)
551 set
= get_alias_set (TREE_TYPE (t
));
554 /* Otherwise make a new alias set for this type. */
555 set
= new_alias_set ();
557 TYPE_ALIAS_SET (t
) = set
;
559 /* If this is an aggregate type, we must record any component aliasing
561 if (AGGREGATE_TYPE_P (t
) || TREE_CODE (t
) == COMPLEX_TYPE
)
562 record_component_aliases (t
);
567 /* Return a brand-new alias set. */
569 static GTY(()) HOST_WIDE_INT last_alias_set
;
574 if (flag_strict_aliasing
)
577 VARRAY_GENERIC_PTR_INIT (alias_sets
, 10, "alias sets");
579 VARRAY_GROW (alias_sets
, last_alias_set
+ 2);
580 return ++last_alias_set
;
586 /* Indicate that things in SUBSET can alias things in SUPERSET, but that
587 not everything that aliases SUPERSET also aliases SUBSET. For example,
588 in C, a store to an `int' can alias a load of a structure containing an
589 `int', and vice versa. But it can't alias a load of a 'double' member
590 of the same structure. Here, the structure would be the SUPERSET and
591 `int' the SUBSET. This relationship is also described in the comment at
592 the beginning of this file.
594 This function should be called only once per SUPERSET/SUBSET pair.
596 It is illegal for SUPERSET to be zero; everything is implicitly a
597 subset of alias set zero. */
600 record_alias_subset (HOST_WIDE_INT superset
, HOST_WIDE_INT subset
)
602 alias_set_entry superset_entry
;
603 alias_set_entry subset_entry
;
605 /* It is possible in complex type situations for both sets to be the same,
606 in which case we can ignore this operation. */
607 if (superset
== subset
)
610 gcc_assert (superset
);
612 superset_entry
= get_alias_set_entry (superset
);
613 if (superset_entry
== 0)
615 /* Create an entry for the SUPERSET, so that we have a place to
616 attach the SUBSET. */
617 superset_entry
= ggc_alloc (sizeof (struct alias_set_entry
));
618 superset_entry
->alias_set
= superset
;
619 superset_entry
->children
620 = splay_tree_new_ggc (splay_tree_compare_ints
);
621 superset_entry
->has_zero_child
= 0;
622 VARRAY_GENERIC_PTR (alias_sets
, superset
) = superset_entry
;
626 superset_entry
->has_zero_child
= 1;
629 subset_entry
= get_alias_set_entry (subset
);
630 /* If there is an entry for the subset, enter all of its children
631 (if they are not already present) as children of the SUPERSET. */
634 if (subset_entry
->has_zero_child
)
635 superset_entry
->has_zero_child
= 1;
637 splay_tree_foreach (subset_entry
->children
, insert_subset_children
,
638 superset_entry
->children
);
641 /* Enter the SUBSET itself as a child of the SUPERSET. */
642 splay_tree_insert (superset_entry
->children
,
643 (splay_tree_key
) subset
, 0);
647 /* Record that component types of TYPE, if any, are part of that type for
648 aliasing purposes. For record types, we only record component types
649 for fields that are marked addressable. For array types, we always
650 record the component types, so the front end should not call this
651 function if the individual component aren't addressable. */
654 record_component_aliases (tree type
)
656 HOST_WIDE_INT superset
= get_alias_set (type
);
662 switch (TREE_CODE (type
))
665 if (! TYPE_NONALIASED_COMPONENT (type
))
666 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
671 case QUAL_UNION_TYPE
:
672 /* Recursively record aliases for the base classes, if there are any. */
673 if (TYPE_BINFO (type
))
676 tree binfo
, base_binfo
;
678 for (binfo
= TYPE_BINFO (type
), i
= 0;
679 BINFO_BASE_ITERATE (binfo
, i
, base_binfo
); i
++)
680 record_alias_subset (superset
,
681 get_alias_set (BINFO_TYPE (base_binfo
)));
683 for (field
= TYPE_FIELDS (type
); field
!= 0; field
= TREE_CHAIN (field
))
684 if (TREE_CODE (field
) == FIELD_DECL
&& ! DECL_NONADDRESSABLE_P (field
))
685 record_alias_subset (superset
, get_alias_set (TREE_TYPE (field
)));
689 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
697 /* Allocate an alias set for use in storing and reading from the varargs
700 static GTY(()) HOST_WIDE_INT varargs_set
= -1;
703 get_varargs_alias_set (void)
706 /* We now lower VA_ARG_EXPR, and there's currently no way to attach the
707 varargs alias set to an INDIRECT_REF (FIXME!), so we can't
708 consistently use the varargs alias set for loads from the varargs
709 area. So don't use it anywhere. */
712 if (varargs_set
== -1)
713 varargs_set
= new_alias_set ();
719 /* Likewise, but used for the fixed portions of the frame, e.g., register
722 static GTY(()) HOST_WIDE_INT frame_set
= -1;
725 get_frame_alias_set (void)
728 frame_set
= new_alias_set ();
733 /* Inside SRC, the source of a SET, find a base address. */
736 find_base_value (rtx src
)
740 switch (GET_CODE (src
))
748 /* At the start of a function, argument registers have known base
749 values which may be lost later. Returning an ADDRESS
750 expression here allows optimization based on argument values
751 even when the argument registers are used for other purposes. */
752 if (regno
< FIRST_PSEUDO_REGISTER
&& copying_arguments
)
753 return new_reg_base_value
[regno
];
755 /* If a pseudo has a known base value, return it. Do not do this
756 for non-fixed hard regs since it can result in a circular
757 dependency chain for registers which have values at function entry.
759 The test above is not sufficient because the scheduler may move
760 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
761 if ((regno
>= FIRST_PSEUDO_REGISTER
|| fixed_regs
[regno
])
762 && regno
< VARRAY_SIZE (reg_base_value
))
764 /* If we're inside init_alias_analysis, use new_reg_base_value
765 to reduce the number of relaxation iterations. */
766 if (new_reg_base_value
&& new_reg_base_value
[regno
]
767 && REG_N_SETS (regno
) == 1)
768 return new_reg_base_value
[regno
];
770 if (VARRAY_RTX (reg_base_value
, regno
))
771 return VARRAY_RTX (reg_base_value
, regno
);
777 /* Check for an argument passed in memory. Only record in the
778 copying-arguments block; it is too hard to track changes
780 if (copying_arguments
781 && (XEXP (src
, 0) == arg_pointer_rtx
782 || (GET_CODE (XEXP (src
, 0)) == PLUS
783 && XEXP (XEXP (src
, 0), 0) == arg_pointer_rtx
)))
784 return gen_rtx_ADDRESS (VOIDmode
, src
);
789 if (GET_CODE (src
) != PLUS
&& GET_CODE (src
) != MINUS
)
792 /* ... fall through ... */
797 rtx temp
, src_0
= XEXP (src
, 0), src_1
= XEXP (src
, 1);
799 /* If either operand is a REG that is a known pointer, then it
801 if (REG_P (src_0
) && REG_POINTER (src_0
))
802 return find_base_value (src_0
);
803 if (REG_P (src_1
) && REG_POINTER (src_1
))
804 return find_base_value (src_1
);
806 /* If either operand is a REG, then see if we already have
807 a known value for it. */
810 temp
= find_base_value (src_0
);
817 temp
= find_base_value (src_1
);
822 /* If either base is named object or a special address
823 (like an argument or stack reference), then use it for the
826 && (GET_CODE (src_0
) == SYMBOL_REF
827 || GET_CODE (src_0
) == LABEL_REF
828 || (GET_CODE (src_0
) == ADDRESS
829 && GET_MODE (src_0
) != VOIDmode
)))
833 && (GET_CODE (src_1
) == SYMBOL_REF
834 || GET_CODE (src_1
) == LABEL_REF
835 || (GET_CODE (src_1
) == ADDRESS
836 && GET_MODE (src_1
) != VOIDmode
)))
839 /* Guess which operand is the base address:
840 If either operand is a symbol, then it is the base. If
841 either operand is a CONST_INT, then the other is the base. */
842 if (GET_CODE (src_1
) == CONST_INT
|| CONSTANT_P (src_0
))
843 return find_base_value (src_0
);
844 else if (GET_CODE (src_0
) == CONST_INT
|| CONSTANT_P (src_1
))
845 return find_base_value (src_1
);
851 /* The standard form is (lo_sum reg sym) so look only at the
853 return find_base_value (XEXP (src
, 1));
856 /* If the second operand is constant set the base
857 address to the first operand. */
858 if (GET_CODE (XEXP (src
, 1)) == CONST_INT
&& INTVAL (XEXP (src
, 1)) != 0)
859 return find_base_value (XEXP (src
, 0));
863 if (GET_MODE_SIZE (GET_MODE (src
)) < GET_MODE_SIZE (Pmode
))
873 return find_base_value (XEXP (src
, 0));
876 case SIGN_EXTEND
: /* used for NT/Alpha pointers */
878 rtx temp
= find_base_value (XEXP (src
, 0));
880 if (temp
!= 0 && CONSTANT_P (temp
))
881 temp
= convert_memory_address (Pmode
, temp
);
893 /* Called from init_alias_analysis indirectly through note_stores. */
895 /* While scanning insns to find base values, reg_seen[N] is nonzero if
896 register N has been set in this function. */
897 static char *reg_seen
;
899 /* Addresses which are known not to alias anything else are identified
900 by a unique integer. */
901 static int unique_id
;
904 record_set (rtx dest
, rtx set
, void *data ATTRIBUTE_UNUSED
)
913 regno
= REGNO (dest
);
915 gcc_assert (regno
< VARRAY_SIZE (reg_base_value
));
917 /* If this spans multiple hard registers, then we must indicate that every
918 register has an unusable value. */
919 if (regno
< FIRST_PSEUDO_REGISTER
)
920 n
= hard_regno_nregs
[regno
][GET_MODE (dest
)];
927 reg_seen
[regno
+ n
] = 1;
928 new_reg_base_value
[regno
+ n
] = 0;
935 /* A CLOBBER wipes out any old value but does not prevent a previously
936 unset register from acquiring a base address (i.e. reg_seen is not
938 if (GET_CODE (set
) == CLOBBER
)
940 new_reg_base_value
[regno
] = 0;
949 new_reg_base_value
[regno
] = 0;
953 new_reg_base_value
[regno
] = gen_rtx_ADDRESS (Pmode
,
954 GEN_INT (unique_id
++));
958 /* If this is not the first set of REGNO, see whether the new value
959 is related to the old one. There are two cases of interest:
961 (1) The register might be assigned an entirely new value
962 that has the same base term as the original set.
964 (2) The set might be a simple self-modification that
965 cannot change REGNO's base value.
967 If neither case holds, reject the original base value as invalid.
968 Note that the following situation is not detected:
970 extern int x, y; int *p = &x; p += (&y-&x);
972 ANSI C does not allow computing the difference of addresses
973 of distinct top level objects. */
974 if (new_reg_base_value
[regno
] != 0
975 && find_base_value (src
) != new_reg_base_value
[regno
])
976 switch (GET_CODE (src
))
980 if (XEXP (src
, 0) != dest
&& XEXP (src
, 1) != dest
)
981 new_reg_base_value
[regno
] = 0;
984 /* If the value we add in the PLUS is also a valid base value,
985 this might be the actual base value, and the original value
988 rtx other
= NULL_RTX
;
990 if (XEXP (src
, 0) == dest
)
991 other
= XEXP (src
, 1);
992 else if (XEXP (src
, 1) == dest
)
993 other
= XEXP (src
, 0);
995 if (! other
|| find_base_value (other
))
996 new_reg_base_value
[regno
] = 0;
1000 if (XEXP (src
, 0) != dest
|| GET_CODE (XEXP (src
, 1)) != CONST_INT
)
1001 new_reg_base_value
[regno
] = 0;
1004 new_reg_base_value
[regno
] = 0;
1007 /* If this is the first set of a register, record the value. */
1008 else if ((regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
1009 && ! reg_seen
[regno
] && new_reg_base_value
[regno
] == 0)
1010 new_reg_base_value
[regno
] = find_base_value (src
);
1012 reg_seen
[regno
] = 1;
1015 /* Called from loop optimization when a new pseudo-register is
1016 created. It indicates that REGNO is being set to VAL. f INVARIANT
1017 is true then this value also describes an invariant relationship
1018 which can be used to deduce that two registers with unknown values
1022 record_base_value (unsigned int regno
, rtx val
, int invariant
)
1024 if (invariant
&& alias_invariant
&& regno
< alias_invariant_size
)
1025 alias_invariant
[regno
] = val
;
1027 if (regno
>= VARRAY_SIZE (reg_base_value
))
1028 VARRAY_GROW (reg_base_value
, max_reg_num ());
1032 VARRAY_RTX (reg_base_value
, regno
)
1033 = REG_BASE_VALUE (val
);
1036 VARRAY_RTX (reg_base_value
, regno
)
1037 = find_base_value (val
);
1040 /* Clear alias info for a register. This is used if an RTL transformation
1041 changes the value of a register. This is used in flow by AUTO_INC_DEC
1042 optimizations. We don't need to clear reg_base_value, since flow only
1043 changes the offset. */
1046 clear_reg_alias_info (rtx reg
)
1048 unsigned int regno
= REGNO (reg
);
1050 if (regno
>= FIRST_PSEUDO_REGISTER
)
1052 regno
-= FIRST_PSEUDO_REGISTER
;
1053 if (regno
< reg_known_value_size
)
1055 reg_known_value
[regno
] = reg
;
1056 reg_known_equiv_p
[regno
] = false;
1061 /* If a value is known for REGNO, return it. */
1064 get_reg_known_value (unsigned int regno
)
1066 if (regno
>= FIRST_PSEUDO_REGISTER
)
1068 regno
-= FIRST_PSEUDO_REGISTER
;
1069 if (regno
< reg_known_value_size
)
1070 return reg_known_value
[regno
];
1078 set_reg_known_value (unsigned int regno
, rtx val
)
1080 if (regno
>= FIRST_PSEUDO_REGISTER
)
1082 regno
-= FIRST_PSEUDO_REGISTER
;
1083 if (regno
< reg_known_value_size
)
1084 reg_known_value
[regno
] = val
;
1088 /* Similarly for reg_known_equiv_p. */
1091 get_reg_known_equiv_p (unsigned int regno
)
1093 if (regno
>= FIRST_PSEUDO_REGISTER
)
1095 regno
-= FIRST_PSEUDO_REGISTER
;
1096 if (regno
< reg_known_value_size
)
1097 return reg_known_equiv_p
[regno
];
1103 set_reg_known_equiv_p (unsigned int regno
, bool val
)
1105 if (regno
>= FIRST_PSEUDO_REGISTER
)
1107 regno
-= FIRST_PSEUDO_REGISTER
;
1108 if (regno
< reg_known_value_size
)
1109 reg_known_equiv_p
[regno
] = val
;
1114 /* Returns a canonical version of X, from the point of view alias
1115 analysis. (For example, if X is a MEM whose address is a register,
1116 and the register has a known value (say a SYMBOL_REF), then a MEM
1117 whose address is the SYMBOL_REF is returned.) */
1122 /* Recursively look for equivalences. */
1123 if (REG_P (x
) && REGNO (x
) >= FIRST_PSEUDO_REGISTER
)
1125 rtx t
= get_reg_known_value (REGNO (x
));
1129 return canon_rtx (t
);
1132 if (GET_CODE (x
) == PLUS
)
1134 rtx x0
= canon_rtx (XEXP (x
, 0));
1135 rtx x1
= canon_rtx (XEXP (x
, 1));
1137 if (x0
!= XEXP (x
, 0) || x1
!= XEXP (x
, 1))
1139 if (GET_CODE (x0
) == CONST_INT
)
1140 return plus_constant (x1
, INTVAL (x0
));
1141 else if (GET_CODE (x1
) == CONST_INT
)
1142 return plus_constant (x0
, INTVAL (x1
));
1143 return gen_rtx_PLUS (GET_MODE (x
), x0
, x1
);
1147 /* This gives us much better alias analysis when called from
1148 the loop optimizer. Note we want to leave the original
1149 MEM alone, but need to return the canonicalized MEM with
1150 all the flags with their original values. */
1152 x
= replace_equiv_address_nv (x
, canon_rtx (XEXP (x
, 0)));
1157 /* Return 1 if X and Y are identical-looking rtx's.
1158 Expect that X and Y has been already canonicalized.
1160 We use the data in reg_known_value above to see if two registers with
1161 different numbers are, in fact, equivalent. */
1164 rtx_equal_for_memref_p (rtx x
, rtx y
)
1171 if (x
== 0 && y
== 0)
1173 if (x
== 0 || y
== 0)
1179 code
= GET_CODE (x
);
1180 /* Rtx's of different codes cannot be equal. */
1181 if (code
!= GET_CODE (y
))
1184 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1185 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1187 if (GET_MODE (x
) != GET_MODE (y
))
1190 /* Some RTL can be compared without a recursive examination. */
1194 return REGNO (x
) == REGNO (y
);
1197 return XEXP (x
, 0) == XEXP (y
, 0);
1200 return XSTR (x
, 0) == XSTR (y
, 0);
1205 /* There's no need to compare the contents of CONST_DOUBLEs or
1206 CONST_INTs because pointer equality is a good enough
1207 comparison for these nodes. */
1214 /* canon_rtx knows how to handle plus. No need to canonicalize. */
1216 return ((rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0))
1217 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 1)))
1218 || (rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 1))
1219 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 0))));
1220 /* For commutative operations, the RTX match if the operand match in any
1221 order. Also handle the simple binary and unary cases without a loop. */
1222 if (COMMUTATIVE_P (x
))
1224 rtx xop0
= canon_rtx (XEXP (x
, 0));
1225 rtx yop0
= canon_rtx (XEXP (y
, 0));
1226 rtx yop1
= canon_rtx (XEXP (y
, 1));
1228 return ((rtx_equal_for_memref_p (xop0
, yop0
)
1229 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop1
))
1230 || (rtx_equal_for_memref_p (xop0
, yop1
)
1231 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop0
)));
1233 else if (NON_COMMUTATIVE_P (x
))
1235 return (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1236 canon_rtx (XEXP (y
, 0)))
1237 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)),
1238 canon_rtx (XEXP (y
, 1))));
1240 else if (UNARY_P (x
))
1241 return rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1242 canon_rtx (XEXP (y
, 0)));
1244 /* Compare the elements. If any pair of corresponding elements
1245 fail to match, return 0 for the whole things.
1247 Limit cases to types which actually appear in addresses. */
1249 fmt
= GET_RTX_FORMAT (code
);
1250 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1255 if (XINT (x
, i
) != XINT (y
, i
))
1260 /* Two vectors must have the same length. */
1261 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1264 /* And the corresponding elements must match. */
1265 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1266 if (rtx_equal_for_memref_p (canon_rtx (XVECEXP (x
, i
, j
)),
1267 canon_rtx (XVECEXP (y
, i
, j
))) == 0)
1272 if (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, i
)),
1273 canon_rtx (XEXP (y
, i
))) == 0)
1277 /* This can happen for asm operands. */
1279 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1283 /* This can happen for an asm which clobbers memory. */
1287 /* It is believed that rtx's at this level will never
1288 contain anything but integers and other rtx's,
1289 except for within LABEL_REFs and SYMBOL_REFs. */
1297 /* Given an rtx X, find a SYMBOL_REF or LABEL_REF within
1298 X and return it, or return 0 if none found. */
1301 find_symbolic_term (rtx x
)
1307 code
= GET_CODE (x
);
1308 if (code
== SYMBOL_REF
|| code
== LABEL_REF
)
1313 fmt
= GET_RTX_FORMAT (code
);
1314 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1320 t
= find_symbolic_term (XEXP (x
, i
));
1324 else if (fmt
[i
] == 'E')
1331 find_base_term (rtx x
)
1334 struct elt_loc_list
*l
;
1336 #if defined (FIND_BASE_TERM)
1337 /* Try machine-dependent ways to find the base term. */
1338 x
= FIND_BASE_TERM (x
);
1341 switch (GET_CODE (x
))
1344 return REG_BASE_VALUE (x
);
1347 if (GET_MODE_SIZE (GET_MODE (x
)) < GET_MODE_SIZE (Pmode
))
1357 return find_base_term (XEXP (x
, 0));
1360 case SIGN_EXTEND
: /* Used for Alpha/NT pointers */
1362 rtx temp
= find_base_term (XEXP (x
, 0));
1364 if (temp
!= 0 && CONSTANT_P (temp
))
1365 temp
= convert_memory_address (Pmode
, temp
);
1371 val
= CSELIB_VAL_PTR (x
);
1374 for (l
= val
->locs
; l
; l
= l
->next
)
1375 if ((x
= find_base_term (l
->loc
)) != 0)
1381 if (GET_CODE (x
) != PLUS
&& GET_CODE (x
) != MINUS
)
1388 rtx tmp1
= XEXP (x
, 0);
1389 rtx tmp2
= XEXP (x
, 1);
1391 /* This is a little bit tricky since we have to determine which of
1392 the two operands represents the real base address. Otherwise this
1393 routine may return the index register instead of the base register.
1395 That may cause us to believe no aliasing was possible, when in
1396 fact aliasing is possible.
1398 We use a few simple tests to guess the base register. Additional
1399 tests can certainly be added. For example, if one of the operands
1400 is a shift or multiply, then it must be the index register and the
1401 other operand is the base register. */
1403 if (tmp1
== pic_offset_table_rtx
&& CONSTANT_P (tmp2
))
1404 return find_base_term (tmp2
);
1406 /* If either operand is known to be a pointer, then use it
1407 to determine the base term. */
1408 if (REG_P (tmp1
) && REG_POINTER (tmp1
))
1409 return find_base_term (tmp1
);
1411 if (REG_P (tmp2
) && REG_POINTER (tmp2
))
1412 return find_base_term (tmp2
);
1414 /* Neither operand was known to be a pointer. Go ahead and find the
1415 base term for both operands. */
1416 tmp1
= find_base_term (tmp1
);
1417 tmp2
= find_base_term (tmp2
);
1419 /* If either base term is named object or a special address
1420 (like an argument or stack reference), then use it for the
1423 && (GET_CODE (tmp1
) == SYMBOL_REF
1424 || GET_CODE (tmp1
) == LABEL_REF
1425 || (GET_CODE (tmp1
) == ADDRESS
1426 && GET_MODE (tmp1
) != VOIDmode
)))
1430 && (GET_CODE (tmp2
) == SYMBOL_REF
1431 || GET_CODE (tmp2
) == LABEL_REF
1432 || (GET_CODE (tmp2
) == ADDRESS
1433 && GET_MODE (tmp2
) != VOIDmode
)))
1436 /* We could not determine which of the two operands was the
1437 base register and which was the index. So we can determine
1438 nothing from the base alias check. */
1443 if (GET_CODE (XEXP (x
, 1)) == CONST_INT
&& INTVAL (XEXP (x
, 1)) != 0)
1444 return find_base_term (XEXP (x
, 0));
1456 /* Return 0 if the addresses X and Y are known to point to different
1457 objects, 1 if they might be pointers to the same object. */
1460 base_alias_check (rtx x
, rtx y
, enum machine_mode x_mode
,
1461 enum machine_mode y_mode
)
1463 rtx x_base
= find_base_term (x
);
1464 rtx y_base
= find_base_term (y
);
1466 /* If the address itself has no known base see if a known equivalent
1467 value has one. If either address still has no known base, nothing
1468 is known about aliasing. */
1473 if (! flag_expensive_optimizations
|| (x_c
= canon_rtx (x
)) == x
)
1476 x_base
= find_base_term (x_c
);
1484 if (! flag_expensive_optimizations
|| (y_c
= canon_rtx (y
)) == y
)
1487 y_base
= find_base_term (y_c
);
1492 /* If the base addresses are equal nothing is known about aliasing. */
1493 if (rtx_equal_p (x_base
, y_base
))
1496 /* The base addresses of the read and write are different expressions.
1497 If they are both symbols and they are not accessed via AND, there is
1498 no conflict. We can bring knowledge of object alignment into play
1499 here. For example, on alpha, "char a, b;" can alias one another,
1500 though "char a; long b;" cannot. */
1501 if (GET_CODE (x_base
) != ADDRESS
&& GET_CODE (y_base
) != ADDRESS
)
1503 if (GET_CODE (x
) == AND
&& GET_CODE (y
) == AND
)
1505 if (GET_CODE (x
) == AND
1506 && (GET_CODE (XEXP (x
, 1)) != CONST_INT
1507 || (int) GET_MODE_UNIT_SIZE (y_mode
) < -INTVAL (XEXP (x
, 1))))
1509 if (GET_CODE (y
) == AND
1510 && (GET_CODE (XEXP (y
, 1)) != CONST_INT
1511 || (int) GET_MODE_UNIT_SIZE (x_mode
) < -INTVAL (XEXP (y
, 1))))
1513 /* Differing symbols never alias. */
1517 /* If one address is a stack reference there can be no alias:
1518 stack references using different base registers do not alias,
1519 a stack reference can not alias a parameter, and a stack reference
1520 can not alias a global. */
1521 if ((GET_CODE (x_base
) == ADDRESS
&& GET_MODE (x_base
) == Pmode
)
1522 || (GET_CODE (y_base
) == ADDRESS
&& GET_MODE (y_base
) == Pmode
))
1525 if (! flag_argument_noalias
)
1528 if (flag_argument_noalias
> 1)
1531 /* Weak noalias assertion (arguments are distinct, but may match globals). */
1532 return ! (GET_MODE (x_base
) == VOIDmode
&& GET_MODE (y_base
) == VOIDmode
);
1535 /* Convert the address X into something we can use. This is done by returning
1536 it unchanged unless it is a value; in the latter case we call cselib to get
1537 a more useful rtx. */
1543 struct elt_loc_list
*l
;
1545 if (GET_CODE (x
) != VALUE
)
1547 v
= CSELIB_VAL_PTR (x
);
1550 for (l
= v
->locs
; l
; l
= l
->next
)
1551 if (CONSTANT_P (l
->loc
))
1553 for (l
= v
->locs
; l
; l
= l
->next
)
1554 if (!REG_P (l
->loc
) && !MEM_P (l
->loc
))
1557 return v
->locs
->loc
;
1562 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
1563 where SIZE is the size in bytes of the memory reference. If ADDR
1564 is not modified by the memory reference then ADDR is returned. */
1567 addr_side_effect_eval (rtx addr
, int size
, int n_refs
)
1571 switch (GET_CODE (addr
))
1574 offset
= (n_refs
+ 1) * size
;
1577 offset
= -(n_refs
+ 1) * size
;
1580 offset
= n_refs
* size
;
1583 offset
= -n_refs
* size
;
1591 addr
= gen_rtx_PLUS (GET_MODE (addr
), XEXP (addr
, 0),
1594 addr
= XEXP (addr
, 0);
1595 addr
= canon_rtx (addr
);
1600 /* Return nonzero if X and Y (memory addresses) could reference the
1601 same location in memory. C is an offset accumulator. When
1602 C is nonzero, we are testing aliases between X and Y + C.
1603 XSIZE is the size in bytes of the X reference,
1604 similarly YSIZE is the size in bytes for Y.
1605 Expect that canon_rtx has been already called for X and Y.
1607 If XSIZE or YSIZE is zero, we do not know the amount of memory being
1608 referenced (the reference was BLKmode), so make the most pessimistic
1611 If XSIZE or YSIZE is negative, we may access memory outside the object
1612 being referenced as a side effect. This can happen when using AND to
1613 align memory references, as is done on the Alpha.
1615 Nice to notice that varying addresses cannot conflict with fp if no
1616 local variables had their addresses taken, but that's too hard now. */
1619 memrefs_conflict_p (int xsize
, rtx x
, int ysize
, rtx y
, HOST_WIDE_INT c
)
1621 if (GET_CODE (x
) == VALUE
)
1623 if (GET_CODE (y
) == VALUE
)
1625 if (GET_CODE (x
) == HIGH
)
1627 else if (GET_CODE (x
) == LO_SUM
)
1630 x
= addr_side_effect_eval (x
, xsize
, 0);
1631 if (GET_CODE (y
) == HIGH
)
1633 else if (GET_CODE (y
) == LO_SUM
)
1636 y
= addr_side_effect_eval (y
, ysize
, 0);
1638 if (rtx_equal_for_memref_p (x
, y
))
1640 if (xsize
<= 0 || ysize
<= 0)
1642 if (c
>= 0 && xsize
> c
)
1644 if (c
< 0 && ysize
+c
> 0)
1649 /* This code used to check for conflicts involving stack references and
1650 globals but the base address alias code now handles these cases. */
1652 if (GET_CODE (x
) == PLUS
)
1654 /* The fact that X is canonicalized means that this
1655 PLUS rtx is canonicalized. */
1656 rtx x0
= XEXP (x
, 0);
1657 rtx x1
= XEXP (x
, 1);
1659 if (GET_CODE (y
) == PLUS
)
1661 /* The fact that Y is canonicalized means that this
1662 PLUS rtx is canonicalized. */
1663 rtx y0
= XEXP (y
, 0);
1664 rtx y1
= XEXP (y
, 1);
1666 if (rtx_equal_for_memref_p (x1
, y1
))
1667 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
1668 if (rtx_equal_for_memref_p (x0
, y0
))
1669 return memrefs_conflict_p (xsize
, x1
, ysize
, y1
, c
);
1670 if (GET_CODE (x1
) == CONST_INT
)
1672 if (GET_CODE (y1
) == CONST_INT
)
1673 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
,
1674 c
- INTVAL (x1
) + INTVAL (y1
));
1676 return memrefs_conflict_p (xsize
, x0
, ysize
, y
,
1679 else if (GET_CODE (y1
) == CONST_INT
)
1680 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
1684 else if (GET_CODE (x1
) == CONST_INT
)
1685 return memrefs_conflict_p (xsize
, x0
, ysize
, y
, c
- INTVAL (x1
));
1687 else if (GET_CODE (y
) == PLUS
)
1689 /* The fact that Y is canonicalized means that this
1690 PLUS rtx is canonicalized. */
1691 rtx y0
= XEXP (y
, 0);
1692 rtx y1
= XEXP (y
, 1);
1694 if (GET_CODE (y1
) == CONST_INT
)
1695 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
1700 if (GET_CODE (x
) == GET_CODE (y
))
1701 switch (GET_CODE (x
))
1705 /* Handle cases where we expect the second operands to be the
1706 same, and check only whether the first operand would conflict
1709 rtx x1
= canon_rtx (XEXP (x
, 1));
1710 rtx y1
= canon_rtx (XEXP (y
, 1));
1711 if (! rtx_equal_for_memref_p (x1
, y1
))
1713 x0
= canon_rtx (XEXP (x
, 0));
1714 y0
= canon_rtx (XEXP (y
, 0));
1715 if (rtx_equal_for_memref_p (x0
, y0
))
1716 return (xsize
== 0 || ysize
== 0
1717 || (c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0));
1719 /* Can't properly adjust our sizes. */
1720 if (GET_CODE (x1
) != CONST_INT
)
1722 xsize
/= INTVAL (x1
);
1723 ysize
/= INTVAL (x1
);
1725 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
1729 /* Are these registers known not to be equal? */
1730 if (alias_invariant
)
1732 unsigned int r_x
= REGNO (x
), r_y
= REGNO (y
);
1733 rtx i_x
, i_y
; /* invariant relationships of X and Y */
1735 i_x
= r_x
>= alias_invariant_size
? 0 : alias_invariant
[r_x
];
1736 i_y
= r_y
>= alias_invariant_size
? 0 : alias_invariant
[r_y
];
1738 if (i_x
== 0 && i_y
== 0)
1741 if (! memrefs_conflict_p (xsize
, i_x
? i_x
: x
,
1742 ysize
, i_y
? i_y
: y
, c
))
1751 /* Treat an access through an AND (e.g. a subword access on an Alpha)
1752 as an access with indeterminate size. Assume that references
1753 besides AND are aligned, so if the size of the other reference is
1754 at least as large as the alignment, assume no other overlap. */
1755 if (GET_CODE (x
) == AND
&& GET_CODE (XEXP (x
, 1)) == CONST_INT
)
1757 if (GET_CODE (y
) == AND
|| ysize
< -INTVAL (XEXP (x
, 1)))
1759 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)), ysize
, y
, c
);
1761 if (GET_CODE (y
) == AND
&& GET_CODE (XEXP (y
, 1)) == CONST_INT
)
1763 /* ??? If we are indexing far enough into the array/structure, we
1764 may yet be able to determine that we can not overlap. But we
1765 also need to that we are far enough from the end not to overlap
1766 a following reference, so we do nothing with that for now. */
1767 if (GET_CODE (x
) == AND
|| xsize
< -INTVAL (XEXP (y
, 1)))
1769 return memrefs_conflict_p (xsize
, x
, ysize
, canon_rtx (XEXP (y
, 0)), c
);
1774 if (GET_CODE (x
) == CONST_INT
&& GET_CODE (y
) == CONST_INT
)
1776 c
+= (INTVAL (y
) - INTVAL (x
));
1777 return (xsize
<= 0 || ysize
<= 0
1778 || (c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0));
1781 if (GET_CODE (x
) == CONST
)
1783 if (GET_CODE (y
) == CONST
)
1784 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
1785 ysize
, canon_rtx (XEXP (y
, 0)), c
);
1787 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
1790 if (GET_CODE (y
) == CONST
)
1791 return memrefs_conflict_p (xsize
, x
, ysize
,
1792 canon_rtx (XEXP (y
, 0)), c
);
1795 return (xsize
<= 0 || ysize
<= 0
1796 || (rtx_equal_for_memref_p (x
, y
)
1797 && ((c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0))));
1804 /* Functions to compute memory dependencies.
1806 Since we process the insns in execution order, we can build tables
1807 to keep track of what registers are fixed (and not aliased), what registers
1808 are varying in known ways, and what registers are varying in unknown
1811 If both memory references are volatile, then there must always be a
1812 dependence between the two references, since their order can not be
1813 changed. A volatile and non-volatile reference can be interchanged
1816 A MEM_IN_STRUCT reference at a non-AND varying address can never
1817 conflict with a non-MEM_IN_STRUCT reference at a fixed address. We
1818 also must allow AND addresses, because they may generate accesses
1819 outside the object being referenced. This is used to generate
1820 aligned addresses from unaligned addresses, for instance, the alpha
1821 storeqi_unaligned pattern. */
1823 /* Read dependence: X is read after read in MEM takes place. There can
1824 only be a dependence here if both reads are volatile. */
1827 read_dependence (rtx mem
, rtx x
)
1829 return MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
);
1832 /* Returns MEM1 if and only if MEM1 is a scalar at a fixed address and
1833 MEM2 is a reference to a structure at a varying address, or returns
1834 MEM2 if vice versa. Otherwise, returns NULL_RTX. If a non-NULL
1835 value is returned MEM1 and MEM2 can never alias. VARIES_P is used
1836 to decide whether or not an address may vary; it should return
1837 nonzero whenever variation is possible.
1838 MEM1_ADDR and MEM2_ADDR are the addresses of MEM1 and MEM2. */
1841 fixed_scalar_and_varying_struct_p (rtx mem1
, rtx mem2
, rtx mem1_addr
,
1843 int (*varies_p
) (rtx
, int))
1845 if (! flag_strict_aliasing
)
1848 if (MEM_SCALAR_P (mem1
) && MEM_IN_STRUCT_P (mem2
)
1849 && !varies_p (mem1_addr
, 1) && varies_p (mem2_addr
, 1))
1850 /* MEM1 is a scalar at a fixed address; MEM2 is a struct at a
1854 if (MEM_IN_STRUCT_P (mem1
) && MEM_SCALAR_P (mem2
)
1855 && varies_p (mem1_addr
, 1) && !varies_p (mem2_addr
, 1))
1856 /* MEM2 is a scalar at a fixed address; MEM1 is a struct at a
1863 /* Returns nonzero if something about the mode or address format MEM1
1864 indicates that it might well alias *anything*. */
1867 aliases_everything_p (rtx mem
)
1869 if (GET_CODE (XEXP (mem
, 0)) == AND
)
1870 /* If the address is an AND, its very hard to know at what it is
1871 actually pointing. */
1877 /* Return true if we can determine that the fields referenced cannot
1878 overlap for any pair of objects. */
1881 nonoverlapping_component_refs_p (tree x
, tree y
)
1883 tree fieldx
, fieldy
, typex
, typey
, orig_y
;
1887 /* The comparison has to be done at a common type, since we don't
1888 know how the inheritance hierarchy works. */
1892 fieldx
= TREE_OPERAND (x
, 1);
1893 typex
= DECL_FIELD_CONTEXT (fieldx
);
1898 fieldy
= TREE_OPERAND (y
, 1);
1899 typey
= DECL_FIELD_CONTEXT (fieldy
);
1904 y
= TREE_OPERAND (y
, 0);
1906 while (y
&& TREE_CODE (y
) == COMPONENT_REF
);
1908 x
= TREE_OPERAND (x
, 0);
1910 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
1912 /* Never found a common type. */
1916 /* If we're left with accessing different fields of a structure,
1918 if (TREE_CODE (typex
) == RECORD_TYPE
1919 && fieldx
!= fieldy
)
1922 /* The comparison on the current field failed. If we're accessing
1923 a very nested structure, look at the next outer level. */
1924 x
= TREE_OPERAND (x
, 0);
1925 y
= TREE_OPERAND (y
, 0);
1928 && TREE_CODE (x
) == COMPONENT_REF
1929 && TREE_CODE (y
) == COMPONENT_REF
);
1934 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
1937 decl_for_component_ref (tree x
)
1941 x
= TREE_OPERAND (x
, 0);
1943 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
1945 return x
&& DECL_P (x
) ? x
: NULL_TREE
;
1948 /* Walk up the COMPONENT_REF list and adjust OFFSET to compensate for the
1949 offset of the field reference. */
1952 adjust_offset_for_component_ref (tree x
, rtx offset
)
1954 HOST_WIDE_INT ioffset
;
1959 ioffset
= INTVAL (offset
);
1962 tree offset
= component_ref_field_offset (x
);
1963 tree field
= TREE_OPERAND (x
, 1);
1965 if (! host_integerp (offset
, 1))
1967 ioffset
+= (tree_low_cst (offset
, 1)
1968 + (tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1)
1971 x
= TREE_OPERAND (x
, 0);
1973 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
1975 return GEN_INT (ioffset
);
1978 /* Return nonzero if we can determine the exprs corresponding to memrefs
1979 X and Y and they do not overlap. */
1982 nonoverlapping_memrefs_p (rtx x
, rtx y
)
1984 tree exprx
= MEM_EXPR (x
), expry
= MEM_EXPR (y
);
1987 rtx moffsetx
, moffsety
;
1988 HOST_WIDE_INT offsetx
= 0, offsety
= 0, sizex
, sizey
, tem
;
1990 /* Unless both have exprs, we can't tell anything. */
1991 if (exprx
== 0 || expry
== 0)
1994 /* If both are field references, we may be able to determine something. */
1995 if (TREE_CODE (exprx
) == COMPONENT_REF
1996 && TREE_CODE (expry
) == COMPONENT_REF
1997 && nonoverlapping_component_refs_p (exprx
, expry
))
2000 /* If the field reference test failed, look at the DECLs involved. */
2001 moffsetx
= MEM_OFFSET (x
);
2002 if (TREE_CODE (exprx
) == COMPONENT_REF
)
2004 tree t
= decl_for_component_ref (exprx
);
2007 moffsetx
= adjust_offset_for_component_ref (exprx
, moffsetx
);
2010 else if (INDIRECT_REF_P (exprx
))
2012 exprx
= TREE_OPERAND (exprx
, 0);
2013 if (flag_argument_noalias
< 2
2014 || TREE_CODE (exprx
) != PARM_DECL
)
2018 moffsety
= MEM_OFFSET (y
);
2019 if (TREE_CODE (expry
) == COMPONENT_REF
)
2021 tree t
= decl_for_component_ref (expry
);
2024 moffsety
= adjust_offset_for_component_ref (expry
, moffsety
);
2027 else if (INDIRECT_REF_P (expry
))
2029 expry
= TREE_OPERAND (expry
, 0);
2030 if (flag_argument_noalias
< 2
2031 || TREE_CODE (expry
) != PARM_DECL
)
2035 if (! DECL_P (exprx
) || ! DECL_P (expry
))
2038 rtlx
= DECL_RTL (exprx
);
2039 rtly
= DECL_RTL (expry
);
2041 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
2042 can't overlap unless they are the same because we never reuse that part
2043 of the stack frame used for locals for spilled pseudos. */
2044 if ((!MEM_P (rtlx
) || !MEM_P (rtly
))
2045 && ! rtx_equal_p (rtlx
, rtly
))
2048 /* Get the base and offsets of both decls. If either is a register, we
2049 know both are and are the same, so use that as the base. The only
2050 we can avoid overlap is if we can deduce that they are nonoverlapping
2051 pieces of that decl, which is very rare. */
2052 basex
= MEM_P (rtlx
) ? XEXP (rtlx
, 0) : rtlx
;
2053 if (GET_CODE (basex
) == PLUS
&& GET_CODE (XEXP (basex
, 1)) == CONST_INT
)
2054 offsetx
= INTVAL (XEXP (basex
, 1)), basex
= XEXP (basex
, 0);
2056 basey
= MEM_P (rtly
) ? XEXP (rtly
, 0) : rtly
;
2057 if (GET_CODE (basey
) == PLUS
&& GET_CODE (XEXP (basey
, 1)) == CONST_INT
)
2058 offsety
= INTVAL (XEXP (basey
, 1)), basey
= XEXP (basey
, 0);
2060 /* If the bases are different, we know they do not overlap if both
2061 are constants or if one is a constant and the other a pointer into the
2062 stack frame. Otherwise a different base means we can't tell if they
2064 if (! rtx_equal_p (basex
, basey
))
2065 return ((CONSTANT_P (basex
) && CONSTANT_P (basey
))
2066 || (CONSTANT_P (basex
) && REG_P (basey
)
2067 && REGNO_PTR_FRAME_P (REGNO (basey
)))
2068 || (CONSTANT_P (basey
) && REG_P (basex
)
2069 && REGNO_PTR_FRAME_P (REGNO (basex
))));
2071 sizex
= (!MEM_P (rtlx
) ? (int) GET_MODE_SIZE (GET_MODE (rtlx
))
2072 : MEM_SIZE (rtlx
) ? INTVAL (MEM_SIZE (rtlx
))
2074 sizey
= (!MEM_P (rtly
) ? (int) GET_MODE_SIZE (GET_MODE (rtly
))
2075 : MEM_SIZE (rtly
) ? INTVAL (MEM_SIZE (rtly
)) :
2078 /* If we have an offset for either memref, it can update the values computed
2081 offsetx
+= INTVAL (moffsetx
), sizex
-= INTVAL (moffsetx
);
2083 offsety
+= INTVAL (moffsety
), sizey
-= INTVAL (moffsety
);
2085 /* If a memref has both a size and an offset, we can use the smaller size.
2086 We can't do this if the offset isn't known because we must view this
2087 memref as being anywhere inside the DECL's MEM. */
2088 if (MEM_SIZE (x
) && moffsetx
)
2089 sizex
= INTVAL (MEM_SIZE (x
));
2090 if (MEM_SIZE (y
) && moffsety
)
2091 sizey
= INTVAL (MEM_SIZE (y
));
2093 /* Put the values of the memref with the lower offset in X's values. */
2094 if (offsetx
> offsety
)
2096 tem
= offsetx
, offsetx
= offsety
, offsety
= tem
;
2097 tem
= sizex
, sizex
= sizey
, sizey
= tem
;
2100 /* If we don't know the size of the lower-offset value, we can't tell
2101 if they conflict. Otherwise, we do the test. */
2102 return sizex
>= 0 && offsety
>= offsetx
+ sizex
;
2105 /* True dependence: X is read after store in MEM takes place. */
2108 true_dependence (rtx mem
, enum machine_mode mem_mode
, rtx x
,
2109 int (*varies
) (rtx
, int))
2111 rtx x_addr
, mem_addr
;
2114 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2117 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2118 This is used in epilogue deallocation functions. */
2119 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2121 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2124 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
2127 /* Read-only memory is by definition never modified, and therefore can't
2128 conflict with anything. We don't expect to find read-only set on MEM,
2129 but stupid user tricks can produce them, so don't abort. */
2130 if (MEM_READONLY_P (x
))
2133 if (nonoverlapping_memrefs_p (mem
, x
))
2136 if (mem_mode
== VOIDmode
)
2137 mem_mode
= GET_MODE (mem
);
2139 x_addr
= get_addr (XEXP (x
, 0));
2140 mem_addr
= get_addr (XEXP (mem
, 0));
2142 base
= find_base_term (x_addr
);
2143 if (base
&& (GET_CODE (base
) == LABEL_REF
2144 || (GET_CODE (base
) == SYMBOL_REF
2145 && CONSTANT_POOL_ADDRESS_P (base
))))
2148 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
), mem_mode
))
2151 x_addr
= canon_rtx (x_addr
);
2152 mem_addr
= canon_rtx (mem_addr
);
2154 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
2155 SIZE_FOR_MODE (x
), x_addr
, 0))
2158 if (aliases_everything_p (x
))
2161 /* We cannot use aliases_everything_p to test MEM, since we must look
2162 at MEM_MODE, rather than GET_MODE (MEM). */
2163 if (mem_mode
== QImode
|| GET_CODE (mem_addr
) == AND
)
2166 /* In true_dependence we also allow BLKmode to alias anything. Why
2167 don't we do this in anti_dependence and output_dependence? */
2168 if (mem_mode
== BLKmode
|| GET_MODE (x
) == BLKmode
)
2171 return ! fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
2175 /* Canonical true dependence: X is read after store in MEM takes place.
2176 Variant of true_dependence which assumes MEM has already been
2177 canonicalized (hence we no longer do that here).
2178 The mem_addr argument has been added, since true_dependence computed
2179 this value prior to canonicalizing. */
2182 canon_true_dependence (rtx mem
, enum machine_mode mem_mode
, rtx mem_addr
,
2183 rtx x
, int (*varies
) (rtx
, int))
2187 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2190 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2191 This is used in epilogue deallocation functions. */
2192 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2194 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2197 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
2200 /* Read-only memory is by definition never modified, and therefore can't
2201 conflict with anything. We don't expect to find read-only set on MEM,
2202 but stupid user tricks can produce them, so don't abort. */
2203 if (MEM_READONLY_P (x
))
2206 if (nonoverlapping_memrefs_p (x
, mem
))
2209 x_addr
= get_addr (XEXP (x
, 0));
2211 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
), mem_mode
))
2214 x_addr
= canon_rtx (x_addr
);
2215 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
2216 SIZE_FOR_MODE (x
), x_addr
, 0))
2219 if (aliases_everything_p (x
))
2222 /* We cannot use aliases_everything_p to test MEM, since we must look
2223 at MEM_MODE, rather than GET_MODE (MEM). */
2224 if (mem_mode
== QImode
|| GET_CODE (mem_addr
) == AND
)
2227 /* In true_dependence we also allow BLKmode to alias anything. Why
2228 don't we do this in anti_dependence and output_dependence? */
2229 if (mem_mode
== BLKmode
|| GET_MODE (x
) == BLKmode
)
2232 return ! fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
2236 /* Returns nonzero if a write to X might alias a previous read from
2237 (or, if WRITEP is nonzero, a write to) MEM. */
2240 write_dependence_p (rtx mem
, rtx x
, int writep
)
2242 rtx x_addr
, mem_addr
;
2246 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2249 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2250 This is used in epilogue deallocation functions. */
2251 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2253 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2256 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
2259 /* A read from read-only memory can't conflict with read-write memory. */
2260 if (!writep
&& MEM_READONLY_P (mem
))
2263 if (nonoverlapping_memrefs_p (x
, mem
))
2266 x_addr
= get_addr (XEXP (x
, 0));
2267 mem_addr
= get_addr (XEXP (mem
, 0));
2271 base
= find_base_term (mem_addr
);
2272 if (base
&& (GET_CODE (base
) == LABEL_REF
2273 || (GET_CODE (base
) == SYMBOL_REF
2274 && CONSTANT_POOL_ADDRESS_P (base
))))
2278 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
),
2282 x_addr
= canon_rtx (x_addr
);
2283 mem_addr
= canon_rtx (mem_addr
);
2285 if (!memrefs_conflict_p (SIZE_FOR_MODE (mem
), mem_addr
,
2286 SIZE_FOR_MODE (x
), x_addr
, 0))
2290 = fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
2293 return (!(fixed_scalar
== mem
&& !aliases_everything_p (x
))
2294 && !(fixed_scalar
== x
&& !aliases_everything_p (mem
)));
2297 /* Anti dependence: X is written after read in MEM takes place. */
2300 anti_dependence (rtx mem
, rtx x
)
2302 return write_dependence_p (mem
, x
, /*writep=*/0);
2305 /* Output dependence: X is written after store in MEM takes place. */
2308 output_dependence (rtx mem
, rtx x
)
2310 return write_dependence_p (mem
, x
, /*writep=*/1);
2313 /* A subroutine of nonlocal_mentioned_p, returns 1 if *LOC mentions
2314 something which is not local to the function and is not constant. */
2317 nonlocal_mentioned_p_1 (rtx
*loc
, void *data ATTRIBUTE_UNUSED
)
2326 switch (GET_CODE (x
))
2329 if (REG_P (SUBREG_REG (x
)))
2331 /* Global registers are not local. */
2332 if (REGNO (SUBREG_REG (x
)) < FIRST_PSEUDO_REGISTER
2333 && global_regs
[subreg_regno (x
)])
2341 /* Global registers are not local. */
2342 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2357 /* Constants in the function's constants pool are constant. */
2358 if (CONSTANT_POOL_ADDRESS_P (x
))
2363 /* Non-constant calls and recursion are not local. */
2367 /* Be overly conservative and consider any volatile memory
2368 reference as not local. */
2369 if (MEM_VOLATILE_P (x
))
2371 base
= find_base_term (XEXP (x
, 0));
2374 /* A Pmode ADDRESS could be a reference via the structure value
2375 address or static chain. Such memory references are nonlocal.
2377 Thus, we have to examine the contents of the ADDRESS to find
2378 out if this is a local reference or not. */
2379 if (GET_CODE (base
) == ADDRESS
2380 && GET_MODE (base
) == Pmode
2381 && (XEXP (base
, 0) == stack_pointer_rtx
2382 || XEXP (base
, 0) == arg_pointer_rtx
2383 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2384 || XEXP (base
, 0) == hard_frame_pointer_rtx
2386 || XEXP (base
, 0) == frame_pointer_rtx
))
2388 /* Constants in the function's constant pool are constant. */
2389 if (GET_CODE (base
) == SYMBOL_REF
&& CONSTANT_POOL_ADDRESS_P (base
))
2394 case UNSPEC_VOLATILE
:
2399 if (MEM_VOLATILE_P (x
))
2411 /* Returns nonzero if X might mention something which is not
2412 local to the function and is not constant. */
2415 nonlocal_mentioned_p (rtx x
)
2421 if (! CONST_OR_PURE_CALL_P (x
))
2423 x
= CALL_INSN_FUNCTION_USAGE (x
);
2431 return for_each_rtx (&x
, nonlocal_mentioned_p_1
, NULL
);
2434 /* A subroutine of nonlocal_referenced_p, returns 1 if *LOC references
2435 something which is not local to the function and is not constant. */
2438 nonlocal_referenced_p_1 (rtx
*loc
, void *data ATTRIBUTE_UNUSED
)
2445 switch (GET_CODE (x
))
2451 return nonlocal_mentioned_p (x
);
2454 /* Non-constant calls and recursion are not local. */
2458 if (nonlocal_mentioned_p (SET_SRC (x
)))
2461 if (MEM_P (SET_DEST (x
)))
2462 return nonlocal_mentioned_p (XEXP (SET_DEST (x
), 0));
2464 /* If the destination is anything other than a CC0, PC,
2465 MEM, REG, or a SUBREG of a REG that occupies all of
2466 the REG, then X references nonlocal memory if it is
2467 mentioned in the destination. */
2468 if (GET_CODE (SET_DEST (x
)) != CC0
2469 && GET_CODE (SET_DEST (x
)) != PC
2470 && !REG_P (SET_DEST (x
))
2471 && ! (GET_CODE (SET_DEST (x
)) == SUBREG
2472 && REG_P (SUBREG_REG (SET_DEST (x
)))
2473 && (((GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (x
))))
2474 + (UNITS_PER_WORD
- 1)) / UNITS_PER_WORD
)
2475 == ((GET_MODE_SIZE (GET_MODE (SET_DEST (x
)))
2476 + (UNITS_PER_WORD
- 1)) / UNITS_PER_WORD
))))
2477 return nonlocal_mentioned_p (SET_DEST (x
));
2481 if (MEM_P (XEXP (x
, 0)))
2482 return nonlocal_mentioned_p (XEXP (XEXP (x
, 0), 0));
2486 return nonlocal_mentioned_p (XEXP (x
, 0));
2489 case UNSPEC_VOLATILE
:
2493 if (MEM_VOLATILE_P (x
))
2505 /* Returns nonzero if X might reference something which is not
2506 local to the function and is not constant. */
2509 nonlocal_referenced_p (rtx x
)
2515 if (! CONST_OR_PURE_CALL_P (x
))
2517 x
= CALL_INSN_FUNCTION_USAGE (x
);
2525 return for_each_rtx (&x
, nonlocal_referenced_p_1
, NULL
);
2528 /* A subroutine of nonlocal_set_p, returns 1 if *LOC sets
2529 something which is not local to the function and is not constant. */
2532 nonlocal_set_p_1 (rtx
*loc
, void *data ATTRIBUTE_UNUSED
)
2539 switch (GET_CODE (x
))
2542 /* Non-constant calls and recursion are not local. */
2551 return nonlocal_mentioned_p (XEXP (x
, 0));
2554 if (nonlocal_mentioned_p (SET_DEST (x
)))
2556 return nonlocal_set_p (SET_SRC (x
));
2559 return nonlocal_mentioned_p (XEXP (x
, 0));
2565 case UNSPEC_VOLATILE
:
2569 if (MEM_VOLATILE_P (x
))
2581 /* Returns nonzero if X might set something which is not
2582 local to the function and is not constant. */
2585 nonlocal_set_p (rtx x
)
2591 if (! CONST_OR_PURE_CALL_P (x
))
2593 x
= CALL_INSN_FUNCTION_USAGE (x
);
2601 return for_each_rtx (&x
, nonlocal_set_p_1
, NULL
);
2604 /* Mark the function if it is pure or constant. */
2607 mark_constant_function (void)
2610 int nonlocal_memory_referenced
;
2612 if (TREE_READONLY (current_function_decl
)
2613 || DECL_IS_PURE (current_function_decl
)
2614 || TREE_THIS_VOLATILE (current_function_decl
)
2615 || current_function_has_nonlocal_goto
2616 || !targetm
.binds_local_p (current_function_decl
))
2619 /* A loop might not return which counts as a side effect. */
2620 if (mark_dfs_back_edges ())
2623 nonlocal_memory_referenced
= 0;
2625 init_alias_analysis ();
2627 /* Determine if this is a constant or pure function. */
2629 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
2631 if (! INSN_P (insn
))
2634 if (nonlocal_set_p (insn
) || global_reg_mentioned_p (insn
)
2635 || volatile_refs_p (PATTERN (insn
)))
2638 if (! nonlocal_memory_referenced
)
2639 nonlocal_memory_referenced
= nonlocal_referenced_p (insn
);
2642 end_alias_analysis ();
2644 /* Mark the function. */
2648 else if (nonlocal_memory_referenced
)
2650 cgraph_rtl_info (current_function_decl
)->pure_function
= 1;
2651 DECL_IS_PURE (current_function_decl
) = 1;
2655 cgraph_rtl_info (current_function_decl
)->const_function
= 1;
2656 TREE_READONLY (current_function_decl
) = 1;
2662 init_alias_once (void)
2666 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2667 /* Check whether this register can hold an incoming pointer
2668 argument. FUNCTION_ARG_REGNO_P tests outgoing register
2669 numbers, so translate if necessary due to register windows. */
2670 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i
))
2671 && HARD_REGNO_MODE_OK (i
, Pmode
))
2672 static_reg_base_value
[i
]
2673 = gen_rtx_ADDRESS (VOIDmode
, gen_rtx_REG (Pmode
, i
));
2675 static_reg_base_value
[STACK_POINTER_REGNUM
]
2676 = gen_rtx_ADDRESS (Pmode
, stack_pointer_rtx
);
2677 static_reg_base_value
[ARG_POINTER_REGNUM
]
2678 = gen_rtx_ADDRESS (Pmode
, arg_pointer_rtx
);
2679 static_reg_base_value
[FRAME_POINTER_REGNUM
]
2680 = gen_rtx_ADDRESS (Pmode
, frame_pointer_rtx
);
2681 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2682 static_reg_base_value
[HARD_FRAME_POINTER_REGNUM
]
2683 = gen_rtx_ADDRESS (Pmode
, hard_frame_pointer_rtx
);
2687 /* Set MEMORY_MODIFIED when X modifies DATA (that is assumed
2688 to be memory reference. */
2689 static bool memory_modified
;
2691 memory_modified_1 (rtx x
, rtx pat ATTRIBUTE_UNUSED
, void *data
)
2695 if (anti_dependence (x
, (rtx
)data
) || output_dependence (x
, (rtx
)data
))
2696 memory_modified
= true;
2701 /* Return true when INSN possibly modify memory contents of MEM
2702 (i.e. address can be modified). */
2704 memory_modified_in_insn_p (rtx mem
, rtx insn
)
2708 memory_modified
= false;
2709 note_stores (PATTERN (insn
), memory_modified_1
, mem
);
2710 return memory_modified
;
2713 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
2717 init_alias_analysis (void)
2719 unsigned int maxreg
= max_reg_num ();
2725 timevar_push (TV_ALIAS_ANALYSIS
);
2727 reg_known_value_size
= maxreg
- FIRST_PSEUDO_REGISTER
;
2728 reg_known_value
= ggc_calloc (reg_known_value_size
, sizeof (rtx
));
2729 reg_known_equiv_p
= xcalloc (reg_known_value_size
, sizeof (bool));
2731 /* Overallocate reg_base_value to allow some growth during loop
2732 optimization. Loop unrolling can create a large number of
2734 if (old_reg_base_value
)
2736 reg_base_value
= old_reg_base_value
;
2737 /* If varray gets large zeroing cost may get important. */
2738 if (VARRAY_SIZE (reg_base_value
) > 256
2739 && VARRAY_SIZE (reg_base_value
) > 4 * maxreg
)
2740 VARRAY_GROW (reg_base_value
, maxreg
);
2741 VARRAY_CLEAR (reg_base_value
);
2742 if (VARRAY_SIZE (reg_base_value
) < maxreg
)
2743 VARRAY_GROW (reg_base_value
, maxreg
);
2747 VARRAY_RTX_INIT (reg_base_value
, maxreg
, "reg_base_value");
2750 new_reg_base_value
= xmalloc (maxreg
* sizeof (rtx
));
2751 reg_seen
= xmalloc (maxreg
);
2753 /* The basic idea is that each pass through this loop will use the
2754 "constant" information from the previous pass to propagate alias
2755 information through another level of assignments.
2757 This could get expensive if the assignment chains are long. Maybe
2758 we should throttle the number of iterations, possibly based on
2759 the optimization level or flag_expensive_optimizations.
2761 We could propagate more information in the first pass by making use
2762 of REG_N_SETS to determine immediately that the alias information
2763 for a pseudo is "constant".
2765 A program with an uninitialized variable can cause an infinite loop
2766 here. Instead of doing a full dataflow analysis to detect such problems
2767 we just cap the number of iterations for the loop.
2769 The state of the arrays for the set chain in question does not matter
2770 since the program has undefined behavior. */
2775 /* Assume nothing will change this iteration of the loop. */
2778 /* We want to assign the same IDs each iteration of this loop, so
2779 start counting from zero each iteration of the loop. */
2782 /* We're at the start of the function each iteration through the
2783 loop, so we're copying arguments. */
2784 copying_arguments
= true;
2786 /* Wipe the potential alias information clean for this pass. */
2787 memset (new_reg_base_value
, 0, maxreg
* sizeof (rtx
));
2789 /* Wipe the reg_seen array clean. */
2790 memset (reg_seen
, 0, maxreg
);
2792 /* Mark all hard registers which may contain an address.
2793 The stack, frame and argument pointers may contain an address.
2794 An argument register which can hold a Pmode value may contain
2795 an address even if it is not in BASE_REGS.
2797 The address expression is VOIDmode for an argument and
2798 Pmode for other registers. */
2800 memcpy (new_reg_base_value
, static_reg_base_value
,
2801 FIRST_PSEUDO_REGISTER
* sizeof (rtx
));
2803 /* Walk the insns adding values to the new_reg_base_value array. */
2804 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
2810 #if defined (HAVE_prologue) || defined (HAVE_epilogue)
2811 /* The prologue/epilogue insns are not threaded onto the
2812 insn chain until after reload has completed. Thus,
2813 there is no sense wasting time checking if INSN is in
2814 the prologue/epilogue until after reload has completed. */
2815 if (reload_completed
2816 && prologue_epilogue_contains (insn
))
2820 /* If this insn has a noalias note, process it, Otherwise,
2821 scan for sets. A simple set will have no side effects
2822 which could change the base value of any other register. */
2824 if (GET_CODE (PATTERN (insn
)) == SET
2825 && REG_NOTES (insn
) != 0
2826 && find_reg_note (insn
, REG_NOALIAS
, NULL_RTX
))
2827 record_set (SET_DEST (PATTERN (insn
)), NULL_RTX
, NULL
);
2829 note_stores (PATTERN (insn
), record_set
, NULL
);
2831 set
= single_set (insn
);
2834 && REG_P (SET_DEST (set
))
2835 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
)
2837 unsigned int regno
= REGNO (SET_DEST (set
));
2838 rtx src
= SET_SRC (set
);
2841 if (REG_NOTES (insn
) != 0
2842 && (((note
= find_reg_note (insn
, REG_EQUAL
, 0)) != 0
2843 && REG_N_SETS (regno
) == 1)
2844 || (note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) != 0)
2845 && GET_CODE (XEXP (note
, 0)) != EXPR_LIST
2846 && ! rtx_varies_p (XEXP (note
, 0), 1)
2847 && ! reg_overlap_mentioned_p (SET_DEST (set
),
2850 set_reg_known_value (regno
, XEXP (note
, 0));
2851 set_reg_known_equiv_p (regno
,
2852 REG_NOTE_KIND (note
) == REG_EQUIV
);
2854 else if (REG_N_SETS (regno
) == 1
2855 && GET_CODE (src
) == PLUS
2856 && REG_P (XEXP (src
, 0))
2857 && (t
= get_reg_known_value (REGNO (XEXP (src
, 0))))
2858 && GET_CODE (XEXP (src
, 1)) == CONST_INT
)
2860 t
= plus_constant (t
, INTVAL (XEXP (src
, 1)));
2861 set_reg_known_value (regno
, t
);
2862 set_reg_known_equiv_p (regno
, 0);
2864 else if (REG_N_SETS (regno
) == 1
2865 && ! rtx_varies_p (src
, 1))
2867 set_reg_known_value (regno
, src
);
2868 set_reg_known_equiv_p (regno
, 0);
2872 else if (NOTE_P (insn
)
2873 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_BEG
)
2874 copying_arguments
= false;
2877 /* Now propagate values from new_reg_base_value to reg_base_value. */
2878 gcc_assert (maxreg
== (unsigned int) max_reg_num());
2880 for (ui
= 0; ui
< maxreg
; ui
++)
2882 if (new_reg_base_value
[ui
]
2883 && new_reg_base_value
[ui
] != VARRAY_RTX (reg_base_value
, ui
)
2884 && ! rtx_equal_p (new_reg_base_value
[ui
],
2885 VARRAY_RTX (reg_base_value
, ui
)))
2887 VARRAY_RTX (reg_base_value
, ui
) = new_reg_base_value
[ui
];
2892 while (changed
&& ++pass
< MAX_ALIAS_LOOP_PASSES
);
2894 /* Fill in the remaining entries. */
2895 for (i
= 0; i
< (int)reg_known_value_size
; i
++)
2896 if (reg_known_value
[i
] == 0)
2897 reg_known_value
[i
] = regno_reg_rtx
[i
+ FIRST_PSEUDO_REGISTER
];
2899 /* Simplify the reg_base_value array so that no register refers to
2900 another register, except to special registers indirectly through
2901 ADDRESS expressions.
2903 In theory this loop can take as long as O(registers^2), but unless
2904 there are very long dependency chains it will run in close to linear
2907 This loop may not be needed any longer now that the main loop does
2908 a better job at propagating alias information. */
2914 for (ui
= 0; ui
< maxreg
; ui
++)
2916 rtx base
= VARRAY_RTX (reg_base_value
, ui
);
2917 if (base
&& REG_P (base
))
2919 unsigned int base_regno
= REGNO (base
);
2920 if (base_regno
== ui
) /* register set from itself */
2921 VARRAY_RTX (reg_base_value
, ui
) = 0;
2923 VARRAY_RTX (reg_base_value
, ui
)
2924 = VARRAY_RTX (reg_base_value
, base_regno
);
2929 while (changed
&& pass
< MAX_ALIAS_LOOP_PASSES
);
2932 free (new_reg_base_value
);
2933 new_reg_base_value
= 0;
2936 timevar_pop (TV_ALIAS_ANALYSIS
);
2940 end_alias_analysis (void)
2942 old_reg_base_value
= reg_base_value
;
2943 ggc_free (reg_known_value
);
2944 reg_known_value
= 0;
2945 reg_known_value_size
= 0;
2946 free (reg_known_equiv_p
);
2947 reg_known_equiv_p
= 0;
2948 if (alias_invariant
)
2950 ggc_free (alias_invariant
);
2951 alias_invariant
= 0;
2952 alias_invariant_size
= 0;
2956 #include "gt-alias.h"