1 /* Alias analysis for GNU C
2 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
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, 51 Franklin Street, Fifth Floor, 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"
47 #include "tree-pass.h"
49 /* The alias sets assigned to MEMs assist the back-end in determining
50 which MEMs can alias which other MEMs. In general, two MEMs in
51 different alias sets cannot alias each other, with one important
52 exception. Consider something like:
54 struct S { int i; double d; };
56 a store to an `S' can alias something of either type `int' or type
57 `double'. (However, a store to an `int' cannot alias a `double'
58 and vice versa.) We indicate this via a tree structure that looks
66 (The arrows are directed and point downwards.)
67 In this situation we say the alias set for `struct S' is the
68 `superset' and that those for `int' and `double' are `subsets'.
70 To see whether two alias sets can point to the same memory, we must
71 see if either alias set is a subset of the other. We need not trace
72 past immediate descendants, however, since we propagate all
73 grandchildren up one level.
75 Alias set zero is implicitly a superset of all other alias sets.
76 However, this is no actual entry for alias set zero. It is an
77 error to attempt to explicitly construct a subset of zero. */
79 struct alias_set_entry
GTY(())
81 /* The alias set number, as stored in MEM_ALIAS_SET. */
82 HOST_WIDE_INT alias_set
;
84 /* The children of the alias set. These are not just the immediate
85 children, but, in fact, all descendants. So, if we have:
87 struct T { struct S s; float f; }
89 continuing our example above, the children here will be all of
90 `int', `double', `float', and `struct S'. */
91 splay_tree
GTY((param1_is (int), param2_is (int))) children
;
93 /* Nonzero if would have a child of zero: this effectively makes this
94 alias set the same as alias set zero. */
97 typedef struct alias_set_entry
*alias_set_entry
;
99 static int rtx_equal_for_memref_p (rtx
, rtx
);
100 static rtx
find_symbolic_term (rtx
);
101 static int memrefs_conflict_p (int, rtx
, int, rtx
, HOST_WIDE_INT
);
102 static void record_set (rtx
, rtx
, void *);
103 static int base_alias_check (rtx
, rtx
, enum machine_mode
,
105 static rtx
find_base_value (rtx
);
106 static int mems_in_disjoint_alias_sets_p (rtx
, rtx
);
107 static int insert_subset_children (splay_tree_node
, void*);
108 static tree
find_base_decl (tree
);
109 static alias_set_entry
get_alias_set_entry (HOST_WIDE_INT
);
110 static rtx
fixed_scalar_and_varying_struct_p (rtx
, rtx
, rtx
, rtx
,
112 static int aliases_everything_p (rtx
);
113 static bool nonoverlapping_component_refs_p (tree
, tree
);
114 static tree
decl_for_component_ref (tree
);
115 static rtx
adjust_offset_for_component_ref (tree
, rtx
);
116 static int nonoverlapping_memrefs_p (rtx
, rtx
);
117 static int write_dependence_p (rtx
, rtx
, int);
119 static int nonlocal_mentioned_p_1 (rtx
*, void *);
120 static int nonlocal_mentioned_p (rtx
);
121 static int nonlocal_referenced_p_1 (rtx
*, void *);
122 static int nonlocal_referenced_p (rtx
);
123 static int nonlocal_set_p_1 (rtx
*, void *);
124 static int nonlocal_set_p (rtx
);
125 static void memory_modified_1 (rtx
, rtx
, void *);
126 static void record_alias_subset (HOST_WIDE_INT
, HOST_WIDE_INT
);
128 /* Set up all info needed to perform alias analysis on memory references. */
130 /* Returns the size in bytes of the mode of X. */
131 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
133 /* Returns nonzero if MEM1 and MEM2 do not alias because they are in
134 different alias sets. We ignore alias sets in functions making use
135 of variable arguments because the va_arg macros on some systems are
137 #define DIFFERENT_ALIAS_SETS_P(MEM1, MEM2) \
138 mems_in_disjoint_alias_sets_p (MEM1, MEM2)
140 /* Cap the number of passes we make over the insns propagating alias
141 information through set chains. 10 is a completely arbitrary choice. */
142 #define MAX_ALIAS_LOOP_PASSES 10
144 /* reg_base_value[N] gives an address to which register N is related.
145 If all sets after the first add or subtract to the current value
146 or otherwise modify it so it does not point to a different top level
147 object, reg_base_value[N] is equal to the address part of the source
150 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
151 expressions represent certain special values: function arguments and
152 the stack, frame, and argument pointers.
154 The contents of an ADDRESS is not normally used, the mode of the
155 ADDRESS determines whether the ADDRESS is a function argument or some
156 other special value. Pointer equality, not rtx_equal_p, determines whether
157 two ADDRESS expressions refer to the same base address.
159 The only use of the contents of an ADDRESS is for determining if the
160 current function performs nonlocal memory memory references for the
161 purposes of marking the function as a constant function. */
163 static GTY(()) varray_type reg_base_value
;
164 static rtx
*new_reg_base_value
;
166 /* We preserve the copy of old array around to avoid amount of garbage
167 produced. About 8% of garbage produced were attributed to this
169 static GTY((deletable
)) varray_type old_reg_base_value
;
171 /* Static hunks of RTL used by the aliasing code; these are initialized
172 once per function to avoid unnecessary RTL allocations. */
173 static GTY (()) rtx static_reg_base_value
[FIRST_PSEUDO_REGISTER
];
175 #define REG_BASE_VALUE(X) \
176 (reg_base_value && REGNO (X) < VARRAY_SIZE (reg_base_value) \
177 ? VARRAY_RTX (reg_base_value, REGNO (X)) : 0)
179 /* Vector of known invariant relationships between registers. Set in
180 loop unrolling. Indexed by register number, if nonzero the value
181 is an expression describing this register in terms of another.
183 The length of this array is REG_BASE_VALUE_SIZE.
185 Because this array contains only pseudo registers it has no effect
187 static GTY((length("alias_invariant_size"))) rtx
*alias_invariant
;
188 static GTY(()) unsigned int alias_invariant_size
;
190 /* Vector indexed by N giving the initial (unchanging) value known for
191 pseudo-register N. This array is initialized in init_alias_analysis,
192 and does not change until end_alias_analysis is called. */
193 static GTY((length("reg_known_value_size"))) rtx
*reg_known_value
;
195 /* Indicates number of valid entries in reg_known_value. */
196 static GTY(()) unsigned int reg_known_value_size
;
198 /* Vector recording for each reg_known_value whether it is due to a
199 REG_EQUIV note. Future passes (viz., reload) may replace the
200 pseudo with the equivalent expression and so we account for the
201 dependences that would be introduced if that happens.
203 The REG_EQUIV notes created in assign_parms may mention the arg
204 pointer, and there are explicit insns in the RTL that modify the
205 arg pointer. Thus we must ensure that such insns don't get
206 scheduled across each other because that would invalidate the
207 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
208 wrong, but solving the problem in the scheduler will likely give
209 better code, so we do it here. */
210 static bool *reg_known_equiv_p
;
212 /* True when scanning insns from the start of the rtl to the
213 NOTE_INSN_FUNCTION_BEG note. */
214 static bool copying_arguments
;
216 /* The splay-tree used to store the various alias set entries. */
217 static GTY ((param_is (struct alias_set_entry
))) varray_type alias_sets
;
219 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
220 such an entry, or NULL otherwise. */
222 static inline alias_set_entry
223 get_alias_set_entry (HOST_WIDE_INT alias_set
)
225 return (alias_set_entry
)VARRAY_GENERIC_PTR (alias_sets
, alias_set
);
228 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
229 the two MEMs cannot alias each other. */
232 mems_in_disjoint_alias_sets_p (rtx mem1
, rtx mem2
)
234 /* Perform a basic sanity check. Namely, that there are no alias sets
235 if we're not using strict aliasing. This helps to catch bugs
236 whereby someone uses PUT_CODE, but doesn't clear MEM_ALIAS_SET, or
237 where a MEM is allocated in some way other than by the use of
238 gen_rtx_MEM, and the MEM_ALIAS_SET is not cleared. If we begin to
239 use alias sets to indicate that spilled registers cannot alias each
240 other, we might need to remove this check. */
241 gcc_assert (flag_strict_aliasing
242 || (!MEM_ALIAS_SET (mem1
) && !MEM_ALIAS_SET (mem2
)));
244 return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1
), MEM_ALIAS_SET (mem2
));
247 /* Insert the NODE into the splay tree given by DATA. Used by
248 record_alias_subset via splay_tree_foreach. */
251 insert_subset_children (splay_tree_node node
, void *data
)
253 splay_tree_insert ((splay_tree
) data
, node
->key
, node
->value
);
258 /* Return 1 if the two specified alias sets may conflict. */
261 alias_sets_conflict_p (HOST_WIDE_INT set1
, HOST_WIDE_INT 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 the two specified alias sets might conflict, or if any subtype
294 of these alias sets might conflict. */
297 alias_sets_might_conflict_p (HOST_WIDE_INT set1
, HOST_WIDE_INT set2
)
299 if (set1
== 0 || set2
== 0 || set1
== set2
)
306 /* Return 1 if any MEM object of type T1 will always conflict (using the
307 dependency routines in this file) with any MEM object of type T2.
308 This is used when allocating temporary storage. If T1 and/or T2 are
309 NULL_TREE, it means we know nothing about the storage. */
312 objects_must_conflict_p (tree t1
, tree t2
)
314 HOST_WIDE_INT set1
, set2
;
316 /* If neither has a type specified, we don't know if they'll conflict
317 because we may be using them to store objects of various types, for
318 example the argument and local variables areas of inlined functions. */
319 if (t1
== 0 && t2
== 0)
322 /* If they are the same type, they must conflict. */
324 /* Likewise if both are volatile. */
325 || (t1
!= 0 && TYPE_VOLATILE (t1
) && t2
!= 0 && TYPE_VOLATILE (t2
)))
328 set1
= t1
? get_alias_set (t1
) : 0;
329 set2
= t2
? get_alias_set (t2
) : 0;
331 /* Otherwise they conflict if they have no alias set or the same. We
332 can't simply use alias_sets_conflict_p here, because we must make
333 sure that every subtype of t1 will conflict with every subtype of
334 t2 for which a pair of subobjects of these respective subtypes
335 overlaps on the stack. */
336 return set1
== 0 || set2
== 0 || set1
== set2
;
339 /* T is an expression with pointer type. Find the DECL on which this
340 expression is based. (For example, in `a[i]' this would be `a'.)
341 If there is no such DECL, or a unique decl cannot be determined,
342 NULL_TREE is returned. */
345 find_base_decl (tree t
)
349 if (t
== 0 || t
== error_mark_node
|| ! POINTER_TYPE_P (TREE_TYPE (t
)))
352 /* If this is a declaration, return it. */
356 /* Handle general expressions. It would be nice to deal with
357 COMPONENT_REFs here. If we could tell that `a' and `b' were the
358 same, then `a->f' and `b->f' are also the same. */
359 switch (TREE_CODE_CLASS (TREE_CODE (t
)))
362 return find_base_decl (TREE_OPERAND (t
, 0));
365 /* Return 0 if found in neither or both are the same. */
366 d0
= find_base_decl (TREE_OPERAND (t
, 0));
367 d1
= find_base_decl (TREE_OPERAND (t
, 1));
382 /* Return true if all nested component references handled by
383 get_inner_reference in T are such that we should use the alias set
384 provided by the object at the heart of T.
386 This is true for non-addressable components (which don't have their
387 own alias set), as well as components of objects in alias set zero.
388 This later point is a special case wherein we wish to override the
389 alias set used by the component, but we don't have per-FIELD_DECL
390 assignable alias sets. */
393 component_uses_parent_alias_set (tree t
)
397 /* If we're at the end, it vacuously uses its own alias set. */
398 if (!handled_component_p (t
))
401 switch (TREE_CODE (t
))
404 if (DECL_NONADDRESSABLE_P (TREE_OPERAND (t
, 1)))
409 case ARRAY_RANGE_REF
:
410 if (TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t
, 0))))
419 /* Bitfields and casts are never addressable. */
423 t
= TREE_OPERAND (t
, 0);
424 if (get_alias_set (TREE_TYPE (t
)) == 0)
429 /* Return the alias set for T, which may be either a type or an
430 expression. Call language-specific routine for help, if needed. */
433 get_alias_set (tree t
)
437 /* If we're not doing any alias analysis, just assume everything
438 aliases everything else. Also return 0 if this or its type is
440 if (! flag_strict_aliasing
|| t
== error_mark_node
442 && (TREE_TYPE (t
) == 0 || TREE_TYPE (t
) == error_mark_node
)))
445 /* We can be passed either an expression or a type. This and the
446 language-specific routine may make mutually-recursive calls to each other
447 to figure out what to do. At each juncture, we see if this is a tree
448 that the language may need to handle specially. First handle things that
454 /* Remove any nops, then give the language a chance to do
455 something with this tree before we look at it. */
457 set
= lang_hooks
.get_alias_set (t
);
461 /* First see if the actual object referenced is an INDIRECT_REF from a
462 restrict-qualified pointer or a "void *". */
463 while (handled_component_p (inner
))
465 inner
= TREE_OPERAND (inner
, 0);
469 /* Check for accesses through restrict-qualified pointers. */
470 if (INDIRECT_REF_P (inner
))
472 tree decl
= find_base_decl (TREE_OPERAND (inner
, 0));
474 if (decl
&& DECL_POINTER_ALIAS_SET_KNOWN_P (decl
))
476 /* If we haven't computed the actual alias set, do it now. */
477 if (DECL_POINTER_ALIAS_SET (decl
) == -2)
479 tree pointed_to_type
= TREE_TYPE (TREE_TYPE (decl
));
481 /* No two restricted pointers can point at the same thing.
482 However, a restricted pointer can point at the same thing
483 as an unrestricted pointer, if that unrestricted pointer
484 is based on the restricted pointer. So, we make the
485 alias set for the restricted pointer a subset of the
486 alias set for the type pointed to by the type of the
488 HOST_WIDE_INT pointed_to_alias_set
489 = get_alias_set (pointed_to_type
);
491 if (pointed_to_alias_set
== 0)
492 /* It's not legal to make a subset of alias set zero. */
493 DECL_POINTER_ALIAS_SET (decl
) = 0;
494 else if (AGGREGATE_TYPE_P (pointed_to_type
))
495 /* For an aggregate, we must treat the restricted
496 pointer the same as an ordinary pointer. If we
497 were to make the type pointed to by the
498 restricted pointer a subset of the pointed-to
499 type, then we would believe that other subsets
500 of the pointed-to type (such as fields of that
501 type) do not conflict with the type pointed to
502 by the restricted pointer. */
503 DECL_POINTER_ALIAS_SET (decl
)
504 = pointed_to_alias_set
;
507 DECL_POINTER_ALIAS_SET (decl
) = new_alias_set ();
508 record_alias_subset (pointed_to_alias_set
,
509 DECL_POINTER_ALIAS_SET (decl
));
513 /* We use the alias set indicated in the declaration. */
514 return DECL_POINTER_ALIAS_SET (decl
);
517 /* If we have an INDIRECT_REF via a void pointer, we don't
518 know anything about what that might alias. Likewise if the
519 pointer is marked that way. */
520 else if (TREE_CODE (TREE_TYPE (inner
)) == VOID_TYPE
521 || (TYPE_REF_CAN_ALIAS_ALL
522 (TREE_TYPE (TREE_OPERAND (inner
, 0)))))
526 /* Otherwise, pick up the outermost object that we could have a pointer
527 to, processing conversions as above. */
528 while (component_uses_parent_alias_set (t
))
530 t
= TREE_OPERAND (t
, 0);
534 /* If we've already determined the alias set for a decl, just return
535 it. This is necessary for C++ anonymous unions, whose component
536 variables don't look like union members (boo!). */
537 if (TREE_CODE (t
) == VAR_DECL
538 && DECL_RTL_SET_P (t
) && MEM_P (DECL_RTL (t
)))
539 return MEM_ALIAS_SET (DECL_RTL (t
));
541 /* Now all we care about is the type. */
545 /* Variant qualifiers don't affect the alias set, so get the main
546 variant. If this is a type with a known alias set, return it. */
547 t
= TYPE_MAIN_VARIANT (t
);
548 if (TYPE_ALIAS_SET_KNOWN_P (t
))
549 return TYPE_ALIAS_SET (t
);
551 /* See if the language has special handling for this type. */
552 set
= lang_hooks
.get_alias_set (t
);
556 /* There are no objects of FUNCTION_TYPE, so there's no point in
557 using up an alias set for them. (There are, of course, pointers
558 and references to functions, but that's different.) */
559 else if (TREE_CODE (t
) == FUNCTION_TYPE
)
562 /* Unless the language specifies otherwise, let vector types alias
563 their components. This avoids some nasty type punning issues in
564 normal usage. And indeed lets vectors be treated more like an
566 else if (TREE_CODE (t
) == VECTOR_TYPE
)
567 set
= get_alias_set (TREE_TYPE (t
));
570 /* Otherwise make a new alias set for this type. */
571 set
= new_alias_set ();
573 TYPE_ALIAS_SET (t
) = set
;
575 /* If this is an aggregate type, we must record any component aliasing
577 if (AGGREGATE_TYPE_P (t
) || TREE_CODE (t
) == COMPLEX_TYPE
)
578 record_component_aliases (t
);
583 /* Return a brand-new alias set. */
585 static GTY(()) HOST_WIDE_INT last_alias_set
;
590 if (flag_strict_aliasing
)
593 VARRAY_GENERIC_PTR_INIT (alias_sets
, 10, "alias sets");
595 VARRAY_GROW (alias_sets
, last_alias_set
+ 2);
596 return ++last_alias_set
;
602 /* Indicate that things in SUBSET can alias things in SUPERSET, but that
603 not everything that aliases SUPERSET also aliases SUBSET. For example,
604 in C, a store to an `int' can alias a load of a structure containing an
605 `int', and vice versa. But it can't alias a load of a 'double' member
606 of the same structure. Here, the structure would be the SUPERSET and
607 `int' the SUBSET. This relationship is also described in the comment at
608 the beginning of this file.
610 This function should be called only once per SUPERSET/SUBSET pair.
612 It is illegal for SUPERSET to be zero; everything is implicitly a
613 subset of alias set zero. */
616 record_alias_subset (HOST_WIDE_INT superset
, HOST_WIDE_INT subset
)
618 alias_set_entry superset_entry
;
619 alias_set_entry subset_entry
;
621 /* It is possible in complex type situations for both sets to be the same,
622 in which case we can ignore this operation. */
623 if (superset
== subset
)
626 gcc_assert (superset
);
628 superset_entry
= get_alias_set_entry (superset
);
629 if (superset_entry
== 0)
631 /* Create an entry for the SUPERSET, so that we have a place to
632 attach the SUBSET. */
633 superset_entry
= ggc_alloc (sizeof (struct alias_set_entry
));
634 superset_entry
->alias_set
= superset
;
635 superset_entry
->children
636 = splay_tree_new_ggc (splay_tree_compare_ints
);
637 superset_entry
->has_zero_child
= 0;
638 VARRAY_GENERIC_PTR (alias_sets
, superset
) = superset_entry
;
642 superset_entry
->has_zero_child
= 1;
645 subset_entry
= get_alias_set_entry (subset
);
646 /* If there is an entry for the subset, enter all of its children
647 (if they are not already present) as children of the SUPERSET. */
650 if (subset_entry
->has_zero_child
)
651 superset_entry
->has_zero_child
= 1;
653 splay_tree_foreach (subset_entry
->children
, insert_subset_children
,
654 superset_entry
->children
);
657 /* Enter the SUBSET itself as a child of the SUPERSET. */
658 splay_tree_insert (superset_entry
->children
,
659 (splay_tree_key
) subset
, 0);
663 /* Record that component types of TYPE, if any, are part of that type for
664 aliasing purposes. For record types, we only record component types
665 for fields that are marked addressable. For array types, we always
666 record the component types, so the front end should not call this
667 function if the individual component aren't addressable. */
670 record_component_aliases (tree type
)
672 HOST_WIDE_INT superset
= get_alias_set (type
);
678 switch (TREE_CODE (type
))
681 if (! TYPE_NONALIASED_COMPONENT (type
))
682 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
687 case QUAL_UNION_TYPE
:
688 /* Recursively record aliases for the base classes, if there are any. */
689 if (TYPE_BINFO (type
))
692 tree binfo
, base_binfo
;
694 for (binfo
= TYPE_BINFO (type
), i
= 0;
695 BINFO_BASE_ITERATE (binfo
, i
, base_binfo
); i
++)
696 record_alias_subset (superset
,
697 get_alias_set (BINFO_TYPE (base_binfo
)));
699 for (field
= TYPE_FIELDS (type
); field
!= 0; field
= TREE_CHAIN (field
))
700 if (TREE_CODE (field
) == FIELD_DECL
&& ! DECL_NONADDRESSABLE_P (field
))
701 record_alias_subset (superset
, get_alias_set (TREE_TYPE (field
)));
705 record_alias_subset (superset
, get_alias_set (TREE_TYPE (type
)));
713 /* Allocate an alias set for use in storing and reading from the varargs
716 static GTY(()) HOST_WIDE_INT varargs_set
= -1;
719 get_varargs_alias_set (void)
722 /* We now lower VA_ARG_EXPR, and there's currently no way to attach the
723 varargs alias set to an INDIRECT_REF (FIXME!), so we can't
724 consistently use the varargs alias set for loads from the varargs
725 area. So don't use it anywhere. */
728 if (varargs_set
== -1)
729 varargs_set
= new_alias_set ();
735 /* Likewise, but used for the fixed portions of the frame, e.g., register
738 static GTY(()) HOST_WIDE_INT frame_set
= -1;
741 get_frame_alias_set (void)
744 frame_set
= new_alias_set ();
749 /* Inside SRC, the source of a SET, find a base address. */
752 find_base_value (rtx src
)
756 switch (GET_CODE (src
))
764 /* At the start of a function, argument registers have known base
765 values which may be lost later. Returning an ADDRESS
766 expression here allows optimization based on argument values
767 even when the argument registers are used for other purposes. */
768 if (regno
< FIRST_PSEUDO_REGISTER
&& copying_arguments
)
769 return new_reg_base_value
[regno
];
771 /* If a pseudo has a known base value, return it. Do not do this
772 for non-fixed hard regs since it can result in a circular
773 dependency chain for registers which have values at function entry.
775 The test above is not sufficient because the scheduler may move
776 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
777 if ((regno
>= FIRST_PSEUDO_REGISTER
|| fixed_regs
[regno
])
778 && regno
< VARRAY_SIZE (reg_base_value
))
780 /* If we're inside init_alias_analysis, use new_reg_base_value
781 to reduce the number of relaxation iterations. */
782 if (new_reg_base_value
&& new_reg_base_value
[regno
]
783 && REG_N_SETS (regno
) == 1)
784 return new_reg_base_value
[regno
];
786 if (VARRAY_RTX (reg_base_value
, regno
))
787 return VARRAY_RTX (reg_base_value
, regno
);
793 /* Check for an argument passed in memory. Only record in the
794 copying-arguments block; it is too hard to track changes
796 if (copying_arguments
797 && (XEXP (src
, 0) == arg_pointer_rtx
798 || (GET_CODE (XEXP (src
, 0)) == PLUS
799 && XEXP (XEXP (src
, 0), 0) == arg_pointer_rtx
)))
800 return gen_rtx_ADDRESS (VOIDmode
, src
);
805 if (GET_CODE (src
) != PLUS
&& GET_CODE (src
) != MINUS
)
808 /* ... fall through ... */
813 rtx temp
, src_0
= XEXP (src
, 0), src_1
= XEXP (src
, 1);
815 /* If either operand is a REG that is a known pointer, then it
817 if (REG_P (src_0
) && REG_POINTER (src_0
))
818 return find_base_value (src_0
);
819 if (REG_P (src_1
) && REG_POINTER (src_1
))
820 return find_base_value (src_1
);
822 /* If either operand is a REG, then see if we already have
823 a known value for it. */
826 temp
= find_base_value (src_0
);
833 temp
= find_base_value (src_1
);
838 /* If either base is named object or a special address
839 (like an argument or stack reference), then use it for the
842 && (GET_CODE (src_0
) == SYMBOL_REF
843 || GET_CODE (src_0
) == LABEL_REF
844 || (GET_CODE (src_0
) == ADDRESS
845 && GET_MODE (src_0
) != VOIDmode
)))
849 && (GET_CODE (src_1
) == SYMBOL_REF
850 || GET_CODE (src_1
) == LABEL_REF
851 || (GET_CODE (src_1
) == ADDRESS
852 && GET_MODE (src_1
) != VOIDmode
)))
855 /* Guess which operand is the base address:
856 If either operand is a symbol, then it is the base. If
857 either operand is a CONST_INT, then the other is the base. */
858 if (GET_CODE (src_1
) == CONST_INT
|| CONSTANT_P (src_0
))
859 return find_base_value (src_0
);
860 else if (GET_CODE (src_0
) == CONST_INT
|| CONSTANT_P (src_1
))
861 return find_base_value (src_1
);
867 /* The standard form is (lo_sum reg sym) so look only at the
869 return find_base_value (XEXP (src
, 1));
872 /* If the second operand is constant set the base
873 address to the first operand. */
874 if (GET_CODE (XEXP (src
, 1)) == CONST_INT
&& INTVAL (XEXP (src
, 1)) != 0)
875 return find_base_value (XEXP (src
, 0));
879 if (GET_MODE_SIZE (GET_MODE (src
)) < GET_MODE_SIZE (Pmode
))
889 return find_base_value (XEXP (src
, 0));
892 case SIGN_EXTEND
: /* used for NT/Alpha pointers */
894 rtx temp
= find_base_value (XEXP (src
, 0));
896 if (temp
!= 0 && CONSTANT_P (temp
))
897 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 (rtx dest
, rtx set
, void *data ATTRIBUTE_UNUSED
)
929 regno
= REGNO (dest
);
931 gcc_assert (regno
< VARRAY_SIZE (reg_base_value
));
933 /* If this spans multiple hard registers, then we must indicate that every
934 register has an unusable value. */
935 if (regno
< FIRST_PSEUDO_REGISTER
)
936 n
= hard_regno_nregs
[regno
][GET_MODE (dest
)];
943 reg_seen
[regno
+ n
] = 1;
944 new_reg_base_value
[regno
+ n
] = 0;
951 /* A CLOBBER wipes out any old value but does not prevent a previously
952 unset register from acquiring a base address (i.e. reg_seen is not
954 if (GET_CODE (set
) == CLOBBER
)
956 new_reg_base_value
[regno
] = 0;
965 new_reg_base_value
[regno
] = 0;
969 new_reg_base_value
[regno
] = gen_rtx_ADDRESS (Pmode
,
970 GEN_INT (unique_id
++));
974 /* If this is not the first set of REGNO, see whether the new value
975 is related to the old one. There are two cases of interest:
977 (1) The register might be assigned an entirely new value
978 that has the same base term as the original set.
980 (2) The set might be a simple self-modification that
981 cannot change REGNO's base value.
983 If neither case holds, reject the original base value as invalid.
984 Note that the following situation is not detected:
986 extern int x, y; int *p = &x; p += (&y-&x);
988 ANSI C does not allow computing the difference of addresses
989 of distinct top level objects. */
990 if (new_reg_base_value
[regno
] != 0
991 && find_base_value (src
) != new_reg_base_value
[regno
])
992 switch (GET_CODE (src
))
996 if (XEXP (src
, 0) != dest
&& XEXP (src
, 1) != dest
)
997 new_reg_base_value
[regno
] = 0;
1000 /* If the value we add in the PLUS is also a valid base value,
1001 this might be the actual base value, and the original value
1004 rtx other
= NULL_RTX
;
1006 if (XEXP (src
, 0) == dest
)
1007 other
= XEXP (src
, 1);
1008 else if (XEXP (src
, 1) == dest
)
1009 other
= XEXP (src
, 0);
1011 if (! other
|| find_base_value (other
))
1012 new_reg_base_value
[regno
] = 0;
1016 if (XEXP (src
, 0) != dest
|| GET_CODE (XEXP (src
, 1)) != CONST_INT
)
1017 new_reg_base_value
[regno
] = 0;
1020 new_reg_base_value
[regno
] = 0;
1023 /* If this is the first set of a register, record the value. */
1024 else if ((regno
>= FIRST_PSEUDO_REGISTER
|| ! fixed_regs
[regno
])
1025 && ! reg_seen
[regno
] && new_reg_base_value
[regno
] == 0)
1026 new_reg_base_value
[regno
] = find_base_value (src
);
1028 reg_seen
[regno
] = 1;
1031 /* Called from loop optimization when a new pseudo-register is
1032 created. It indicates that REGNO is being set to VAL. f INVARIANT
1033 is true then this value also describes an invariant relationship
1034 which can be used to deduce that two registers with unknown values
1038 record_base_value (unsigned int regno
, rtx val
, int invariant
)
1040 if (invariant
&& alias_invariant
&& regno
< alias_invariant_size
)
1041 alias_invariant
[regno
] = val
;
1043 if (regno
>= VARRAY_SIZE (reg_base_value
))
1044 VARRAY_GROW (reg_base_value
, max_reg_num ());
1048 VARRAY_RTX (reg_base_value
, regno
)
1049 = REG_BASE_VALUE (val
);
1052 VARRAY_RTX (reg_base_value
, regno
)
1053 = find_base_value (val
);
1056 /* Clear alias info for a register. This is used if an RTL transformation
1057 changes the value of a register. This is used in flow by AUTO_INC_DEC
1058 optimizations. We don't need to clear reg_base_value, since flow only
1059 changes the offset. */
1062 clear_reg_alias_info (rtx reg
)
1064 unsigned int regno
= REGNO (reg
);
1066 if (regno
>= FIRST_PSEUDO_REGISTER
)
1068 regno
-= FIRST_PSEUDO_REGISTER
;
1069 if (regno
< reg_known_value_size
)
1071 reg_known_value
[regno
] = reg
;
1072 reg_known_equiv_p
[regno
] = false;
1077 /* If a value is known for REGNO, return it. */
1080 get_reg_known_value (unsigned int regno
)
1082 if (regno
>= FIRST_PSEUDO_REGISTER
)
1084 regno
-= FIRST_PSEUDO_REGISTER
;
1085 if (regno
< reg_known_value_size
)
1086 return reg_known_value
[regno
];
1094 set_reg_known_value (unsigned int regno
, rtx val
)
1096 if (regno
>= FIRST_PSEUDO_REGISTER
)
1098 regno
-= FIRST_PSEUDO_REGISTER
;
1099 if (regno
< reg_known_value_size
)
1100 reg_known_value
[regno
] = val
;
1104 /* Similarly for reg_known_equiv_p. */
1107 get_reg_known_equiv_p (unsigned int regno
)
1109 if (regno
>= FIRST_PSEUDO_REGISTER
)
1111 regno
-= FIRST_PSEUDO_REGISTER
;
1112 if (regno
< reg_known_value_size
)
1113 return reg_known_equiv_p
[regno
];
1119 set_reg_known_equiv_p (unsigned int regno
, bool val
)
1121 if (regno
>= FIRST_PSEUDO_REGISTER
)
1123 regno
-= FIRST_PSEUDO_REGISTER
;
1124 if (regno
< reg_known_value_size
)
1125 reg_known_equiv_p
[regno
] = val
;
1130 /* Returns a canonical version of X, from the point of view alias
1131 analysis. (For example, if X is a MEM whose address is a register,
1132 and the register has a known value (say a SYMBOL_REF), then a MEM
1133 whose address is the SYMBOL_REF is returned.) */
1138 /* Recursively look for equivalences. */
1139 if (REG_P (x
) && REGNO (x
) >= FIRST_PSEUDO_REGISTER
)
1141 rtx t
= get_reg_known_value (REGNO (x
));
1145 return canon_rtx (t
);
1148 if (GET_CODE (x
) == PLUS
)
1150 rtx x0
= canon_rtx (XEXP (x
, 0));
1151 rtx x1
= canon_rtx (XEXP (x
, 1));
1153 if (x0
!= XEXP (x
, 0) || x1
!= XEXP (x
, 1))
1155 if (GET_CODE (x0
) == CONST_INT
)
1156 return plus_constant (x1
, INTVAL (x0
));
1157 else if (GET_CODE (x1
) == CONST_INT
)
1158 return plus_constant (x0
, INTVAL (x1
));
1159 return gen_rtx_PLUS (GET_MODE (x
), x0
, x1
);
1163 /* This gives us much better alias analysis when called from
1164 the loop optimizer. Note we want to leave the original
1165 MEM alone, but need to return the canonicalized MEM with
1166 all the flags with their original values. */
1168 x
= replace_equiv_address_nv (x
, canon_rtx (XEXP (x
, 0)));
1173 /* Return 1 if X and Y are identical-looking rtx's.
1174 Expect that X and Y has been already canonicalized.
1176 We use the data in reg_known_value above to see if two registers with
1177 different numbers are, in fact, equivalent. */
1180 rtx_equal_for_memref_p (rtx x
, rtx y
)
1187 if (x
== 0 && y
== 0)
1189 if (x
== 0 || y
== 0)
1195 code
= GET_CODE (x
);
1196 /* Rtx's of different codes cannot be equal. */
1197 if (code
!= GET_CODE (y
))
1200 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1201 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1203 if (GET_MODE (x
) != GET_MODE (y
))
1206 /* Some RTL can be compared without a recursive examination. */
1210 return REGNO (x
) == REGNO (y
);
1213 return XEXP (x
, 0) == XEXP (y
, 0);
1216 return XSTR (x
, 0) == XSTR (y
, 0);
1221 /* There's no need to compare the contents of CONST_DOUBLEs or
1222 CONST_INTs because pointer equality is a good enough
1223 comparison for these nodes. */
1230 /* canon_rtx knows how to handle plus. No need to canonicalize. */
1232 return ((rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 0))
1233 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 1)))
1234 || (rtx_equal_for_memref_p (XEXP (x
, 0), XEXP (y
, 1))
1235 && rtx_equal_for_memref_p (XEXP (x
, 1), XEXP (y
, 0))));
1236 /* For commutative operations, the RTX match if the operand match in any
1237 order. Also handle the simple binary and unary cases without a loop. */
1238 if (COMMUTATIVE_P (x
))
1240 rtx xop0
= canon_rtx (XEXP (x
, 0));
1241 rtx yop0
= canon_rtx (XEXP (y
, 0));
1242 rtx yop1
= canon_rtx (XEXP (y
, 1));
1244 return ((rtx_equal_for_memref_p (xop0
, yop0
)
1245 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop1
))
1246 || (rtx_equal_for_memref_p (xop0
, yop1
)
1247 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)), yop0
)));
1249 else if (NON_COMMUTATIVE_P (x
))
1251 return (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1252 canon_rtx (XEXP (y
, 0)))
1253 && rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 1)),
1254 canon_rtx (XEXP (y
, 1))));
1256 else if (UNARY_P (x
))
1257 return rtx_equal_for_memref_p (canon_rtx (XEXP (x
, 0)),
1258 canon_rtx (XEXP (y
, 0)));
1260 /* Compare the elements. If any pair of corresponding elements
1261 fail to match, return 0 for the whole things.
1263 Limit cases to types which actually appear in addresses. */
1265 fmt
= GET_RTX_FORMAT (code
);
1266 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1271 if (XINT (x
, i
) != XINT (y
, i
))
1276 /* Two vectors must have the same length. */
1277 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1280 /* And the corresponding elements must match. */
1281 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1282 if (rtx_equal_for_memref_p (canon_rtx (XVECEXP (x
, i
, j
)),
1283 canon_rtx (XVECEXP (y
, i
, j
))) == 0)
1288 if (rtx_equal_for_memref_p (canon_rtx (XEXP (x
, i
)),
1289 canon_rtx (XEXP (y
, i
))) == 0)
1293 /* This can happen for asm operands. */
1295 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1299 /* This can happen for an asm which clobbers memory. */
1303 /* It is believed that rtx's at this level will never
1304 contain anything but integers and other rtx's,
1305 except for within LABEL_REFs and SYMBOL_REFs. */
1313 /* Given an rtx X, find a SYMBOL_REF or LABEL_REF within
1314 X and return it, or return 0 if none found. */
1317 find_symbolic_term (rtx x
)
1323 code
= GET_CODE (x
);
1324 if (code
== SYMBOL_REF
|| code
== LABEL_REF
)
1329 fmt
= GET_RTX_FORMAT (code
);
1330 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1336 t
= find_symbolic_term (XEXP (x
, i
));
1340 else if (fmt
[i
] == 'E')
1347 find_base_term (rtx x
)
1350 struct elt_loc_list
*l
;
1352 #if defined (FIND_BASE_TERM)
1353 /* Try machine-dependent ways to find the base term. */
1354 x
= FIND_BASE_TERM (x
);
1357 switch (GET_CODE (x
))
1360 return REG_BASE_VALUE (x
);
1363 if (GET_MODE_SIZE (GET_MODE (x
)) < GET_MODE_SIZE (Pmode
))
1373 return find_base_term (XEXP (x
, 0));
1376 case SIGN_EXTEND
: /* Used for Alpha/NT pointers */
1378 rtx temp
= find_base_term (XEXP (x
, 0));
1380 if (temp
!= 0 && CONSTANT_P (temp
))
1381 temp
= convert_memory_address (Pmode
, temp
);
1387 val
= CSELIB_VAL_PTR (x
);
1390 for (l
= val
->locs
; l
; l
= l
->next
)
1391 if ((x
= find_base_term (l
->loc
)) != 0)
1397 if (GET_CODE (x
) != PLUS
&& GET_CODE (x
) != MINUS
)
1404 rtx tmp1
= XEXP (x
, 0);
1405 rtx tmp2
= XEXP (x
, 1);
1407 /* This is a little bit tricky since we have to determine which of
1408 the two operands represents the real base address. Otherwise this
1409 routine may return the index register instead of the base register.
1411 That may cause us to believe no aliasing was possible, when in
1412 fact aliasing is possible.
1414 We use a few simple tests to guess the base register. Additional
1415 tests can certainly be added. For example, if one of the operands
1416 is a shift or multiply, then it must be the index register and the
1417 other operand is the base register. */
1419 if (tmp1
== pic_offset_table_rtx
&& CONSTANT_P (tmp2
))
1420 return find_base_term (tmp2
);
1422 /* If either operand is known to be a pointer, then use it
1423 to determine the base term. */
1424 if (REG_P (tmp1
) && REG_POINTER (tmp1
))
1425 return find_base_term (tmp1
);
1427 if (REG_P (tmp2
) && REG_POINTER (tmp2
))
1428 return find_base_term (tmp2
);
1430 /* Neither operand was known to be a pointer. Go ahead and find the
1431 base term for both operands. */
1432 tmp1
= find_base_term (tmp1
);
1433 tmp2
= find_base_term (tmp2
);
1435 /* If either base term is named object or a special address
1436 (like an argument or stack reference), then use it for the
1439 && (GET_CODE (tmp1
) == SYMBOL_REF
1440 || GET_CODE (tmp1
) == LABEL_REF
1441 || (GET_CODE (tmp1
) == ADDRESS
1442 && GET_MODE (tmp1
) != VOIDmode
)))
1446 && (GET_CODE (tmp2
) == SYMBOL_REF
1447 || GET_CODE (tmp2
) == LABEL_REF
1448 || (GET_CODE (tmp2
) == ADDRESS
1449 && GET_MODE (tmp2
) != VOIDmode
)))
1452 /* We could not determine which of the two operands was the
1453 base register and which was the index. So we can determine
1454 nothing from the base alias check. */
1459 if (GET_CODE (XEXP (x
, 1)) == CONST_INT
&& INTVAL (XEXP (x
, 1)) != 0)
1460 return find_base_term (XEXP (x
, 0));
1472 /* Return 0 if the addresses X and Y are known to point to different
1473 objects, 1 if they might be pointers to the same object. */
1476 base_alias_check (rtx x
, rtx y
, enum machine_mode x_mode
,
1477 enum machine_mode y_mode
)
1479 rtx x_base
= find_base_term (x
);
1480 rtx y_base
= find_base_term (y
);
1482 /* If the address itself has no known base see if a known equivalent
1483 value has one. If either address still has no known base, nothing
1484 is known about aliasing. */
1489 if (! flag_expensive_optimizations
|| (x_c
= canon_rtx (x
)) == x
)
1492 x_base
= find_base_term (x_c
);
1500 if (! flag_expensive_optimizations
|| (y_c
= canon_rtx (y
)) == y
)
1503 y_base
= find_base_term (y_c
);
1508 /* If the base addresses are equal nothing is known about aliasing. */
1509 if (rtx_equal_p (x_base
, y_base
))
1512 /* The base addresses of the read and write are different expressions.
1513 If they are both symbols and they are not accessed via AND, there is
1514 no conflict. We can bring knowledge of object alignment into play
1515 here. For example, on alpha, "char a, b;" can alias one another,
1516 though "char a; long b;" cannot. */
1517 if (GET_CODE (x_base
) != ADDRESS
&& GET_CODE (y_base
) != ADDRESS
)
1519 if (GET_CODE (x
) == AND
&& GET_CODE (y
) == AND
)
1521 if (GET_CODE (x
) == AND
1522 && (GET_CODE (XEXP (x
, 1)) != CONST_INT
1523 || (int) GET_MODE_UNIT_SIZE (y_mode
) < -INTVAL (XEXP (x
, 1))))
1525 if (GET_CODE (y
) == AND
1526 && (GET_CODE (XEXP (y
, 1)) != CONST_INT
1527 || (int) GET_MODE_UNIT_SIZE (x_mode
) < -INTVAL (XEXP (y
, 1))))
1529 /* Differing symbols never alias. */
1533 /* If one address is a stack reference there can be no alias:
1534 stack references using different base registers do not alias,
1535 a stack reference can not alias a parameter, and a stack reference
1536 can not alias a global. */
1537 if ((GET_CODE (x_base
) == ADDRESS
&& GET_MODE (x_base
) == Pmode
)
1538 || (GET_CODE (y_base
) == ADDRESS
&& GET_MODE (y_base
) == Pmode
))
1541 if (! flag_argument_noalias
)
1544 if (flag_argument_noalias
> 1)
1547 /* Weak noalias assertion (arguments are distinct, but may match globals). */
1548 return ! (GET_MODE (x_base
) == VOIDmode
&& GET_MODE (y_base
) == VOIDmode
);
1551 /* Convert the address X into something we can use. This is done by returning
1552 it unchanged unless it is a value; in the latter case we call cselib to get
1553 a more useful rtx. */
1559 struct elt_loc_list
*l
;
1561 if (GET_CODE (x
) != VALUE
)
1563 v
= CSELIB_VAL_PTR (x
);
1566 for (l
= v
->locs
; l
; l
= l
->next
)
1567 if (CONSTANT_P (l
->loc
))
1569 for (l
= v
->locs
; l
; l
= l
->next
)
1570 if (!REG_P (l
->loc
) && !MEM_P (l
->loc
))
1573 return v
->locs
->loc
;
1578 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
1579 where SIZE is the size in bytes of the memory reference. If ADDR
1580 is not modified by the memory reference then ADDR is returned. */
1583 addr_side_effect_eval (rtx addr
, int size
, int n_refs
)
1587 switch (GET_CODE (addr
))
1590 offset
= (n_refs
+ 1) * size
;
1593 offset
= -(n_refs
+ 1) * size
;
1596 offset
= n_refs
* size
;
1599 offset
= -n_refs
* size
;
1607 addr
= gen_rtx_PLUS (GET_MODE (addr
), XEXP (addr
, 0),
1610 addr
= XEXP (addr
, 0);
1611 addr
= canon_rtx (addr
);
1616 /* Return nonzero if X and Y (memory addresses) could reference the
1617 same location in memory. C is an offset accumulator. When
1618 C is nonzero, we are testing aliases between X and Y + C.
1619 XSIZE is the size in bytes of the X reference,
1620 similarly YSIZE is the size in bytes for Y.
1621 Expect that canon_rtx has been already called for X and Y.
1623 If XSIZE or YSIZE is zero, we do not know the amount of memory being
1624 referenced (the reference was BLKmode), so make the most pessimistic
1627 If XSIZE or YSIZE is negative, we may access memory outside the object
1628 being referenced as a side effect. This can happen when using AND to
1629 align memory references, as is done on the Alpha.
1631 Nice to notice that varying addresses cannot conflict with fp if no
1632 local variables had their addresses taken, but that's too hard now. */
1635 memrefs_conflict_p (int xsize
, rtx x
, int ysize
, rtx y
, HOST_WIDE_INT c
)
1637 if (GET_CODE (x
) == VALUE
)
1639 if (GET_CODE (y
) == VALUE
)
1641 if (GET_CODE (x
) == HIGH
)
1643 else if (GET_CODE (x
) == LO_SUM
)
1646 x
= addr_side_effect_eval (x
, xsize
, 0);
1647 if (GET_CODE (y
) == HIGH
)
1649 else if (GET_CODE (y
) == LO_SUM
)
1652 y
= addr_side_effect_eval (y
, ysize
, 0);
1654 if (rtx_equal_for_memref_p (x
, y
))
1656 if (xsize
<= 0 || ysize
<= 0)
1658 if (c
>= 0 && xsize
> c
)
1660 if (c
< 0 && ysize
+c
> 0)
1665 /* This code used to check for conflicts involving stack references and
1666 globals but the base address alias code now handles these cases. */
1668 if (GET_CODE (x
) == PLUS
)
1670 /* The fact that X is canonicalized means that this
1671 PLUS rtx is canonicalized. */
1672 rtx x0
= XEXP (x
, 0);
1673 rtx x1
= XEXP (x
, 1);
1675 if (GET_CODE (y
) == PLUS
)
1677 /* The fact that Y is canonicalized means that this
1678 PLUS rtx is canonicalized. */
1679 rtx y0
= XEXP (y
, 0);
1680 rtx y1
= XEXP (y
, 1);
1682 if (rtx_equal_for_memref_p (x1
, y1
))
1683 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
1684 if (rtx_equal_for_memref_p (x0
, y0
))
1685 return memrefs_conflict_p (xsize
, x1
, ysize
, y1
, c
);
1686 if (GET_CODE (x1
) == CONST_INT
)
1688 if (GET_CODE (y1
) == CONST_INT
)
1689 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
,
1690 c
- INTVAL (x1
) + INTVAL (y1
));
1692 return memrefs_conflict_p (xsize
, x0
, ysize
, y
,
1695 else if (GET_CODE (y1
) == CONST_INT
)
1696 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
1700 else if (GET_CODE (x1
) == CONST_INT
)
1701 return memrefs_conflict_p (xsize
, x0
, ysize
, y
, c
- INTVAL (x1
));
1703 else if (GET_CODE (y
) == PLUS
)
1705 /* The fact that Y is canonicalized means that this
1706 PLUS rtx is canonicalized. */
1707 rtx y0
= XEXP (y
, 0);
1708 rtx y1
= XEXP (y
, 1);
1710 if (GET_CODE (y1
) == CONST_INT
)
1711 return memrefs_conflict_p (xsize
, x
, ysize
, y0
, c
+ INTVAL (y1
));
1716 if (GET_CODE (x
) == GET_CODE (y
))
1717 switch (GET_CODE (x
))
1721 /* Handle cases where we expect the second operands to be the
1722 same, and check only whether the first operand would conflict
1725 rtx x1
= canon_rtx (XEXP (x
, 1));
1726 rtx y1
= canon_rtx (XEXP (y
, 1));
1727 if (! rtx_equal_for_memref_p (x1
, y1
))
1729 x0
= canon_rtx (XEXP (x
, 0));
1730 y0
= canon_rtx (XEXP (y
, 0));
1731 if (rtx_equal_for_memref_p (x0
, y0
))
1732 return (xsize
== 0 || ysize
== 0
1733 || (c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0));
1735 /* Can't properly adjust our sizes. */
1736 if (GET_CODE (x1
) != CONST_INT
)
1738 xsize
/= INTVAL (x1
);
1739 ysize
/= INTVAL (x1
);
1741 return memrefs_conflict_p (xsize
, x0
, ysize
, y0
, c
);
1745 /* Are these registers known not to be equal? */
1746 if (alias_invariant
)
1748 unsigned int r_x
= REGNO (x
), r_y
= REGNO (y
);
1749 rtx i_x
, i_y
; /* invariant relationships of X and Y */
1751 i_x
= r_x
>= alias_invariant_size
? 0 : alias_invariant
[r_x
];
1752 i_y
= r_y
>= alias_invariant_size
? 0 : alias_invariant
[r_y
];
1754 if (i_x
== 0 && i_y
== 0)
1757 if (! memrefs_conflict_p (xsize
, i_x
? i_x
: x
,
1758 ysize
, i_y
? i_y
: y
, c
))
1767 /* Treat an access through an AND (e.g. a subword access on an Alpha)
1768 as an access with indeterminate size. Assume that references
1769 besides AND are aligned, so if the size of the other reference is
1770 at least as large as the alignment, assume no other overlap. */
1771 if (GET_CODE (x
) == AND
&& GET_CODE (XEXP (x
, 1)) == CONST_INT
)
1773 if (GET_CODE (y
) == AND
|| ysize
< -INTVAL (XEXP (x
, 1)))
1775 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)), ysize
, y
, c
);
1777 if (GET_CODE (y
) == AND
&& GET_CODE (XEXP (y
, 1)) == CONST_INT
)
1779 /* ??? If we are indexing far enough into the array/structure, we
1780 may yet be able to determine that we can not overlap. But we
1781 also need to that we are far enough from the end not to overlap
1782 a following reference, so we do nothing with that for now. */
1783 if (GET_CODE (x
) == AND
|| xsize
< -INTVAL (XEXP (y
, 1)))
1785 return memrefs_conflict_p (xsize
, x
, ysize
, canon_rtx (XEXP (y
, 0)), c
);
1790 if (GET_CODE (x
) == CONST_INT
&& GET_CODE (y
) == CONST_INT
)
1792 c
+= (INTVAL (y
) - INTVAL (x
));
1793 return (xsize
<= 0 || ysize
<= 0
1794 || (c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0));
1797 if (GET_CODE (x
) == CONST
)
1799 if (GET_CODE (y
) == CONST
)
1800 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
1801 ysize
, canon_rtx (XEXP (y
, 0)), c
);
1803 return memrefs_conflict_p (xsize
, canon_rtx (XEXP (x
, 0)),
1806 if (GET_CODE (y
) == CONST
)
1807 return memrefs_conflict_p (xsize
, x
, ysize
,
1808 canon_rtx (XEXP (y
, 0)), c
);
1811 return (xsize
<= 0 || ysize
<= 0
1812 || (rtx_equal_for_memref_p (x
, y
)
1813 && ((c
>= 0 && xsize
> c
) || (c
< 0 && ysize
+c
> 0))));
1820 /* Functions to compute memory dependencies.
1822 Since we process the insns in execution order, we can build tables
1823 to keep track of what registers are fixed (and not aliased), what registers
1824 are varying in known ways, and what registers are varying in unknown
1827 If both memory references are volatile, then there must always be a
1828 dependence between the two references, since their order can not be
1829 changed. A volatile and non-volatile reference can be interchanged
1832 A MEM_IN_STRUCT reference at a non-AND varying address can never
1833 conflict with a non-MEM_IN_STRUCT reference at a fixed address. We
1834 also must allow AND addresses, because they may generate accesses
1835 outside the object being referenced. This is used to generate
1836 aligned addresses from unaligned addresses, for instance, the alpha
1837 storeqi_unaligned pattern. */
1839 /* Read dependence: X is read after read in MEM takes place. There can
1840 only be a dependence here if both reads are volatile. */
1843 read_dependence (rtx mem
, rtx x
)
1845 return MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
);
1848 /* Returns MEM1 if and only if MEM1 is a scalar at a fixed address and
1849 MEM2 is a reference to a structure at a varying address, or returns
1850 MEM2 if vice versa. Otherwise, returns NULL_RTX. If a non-NULL
1851 value is returned MEM1 and MEM2 can never alias. VARIES_P is used
1852 to decide whether or not an address may vary; it should return
1853 nonzero whenever variation is possible.
1854 MEM1_ADDR and MEM2_ADDR are the addresses of MEM1 and MEM2. */
1857 fixed_scalar_and_varying_struct_p (rtx mem1
, rtx mem2
, rtx mem1_addr
,
1859 int (*varies_p
) (rtx
, int))
1861 if (! flag_strict_aliasing
)
1864 if (MEM_SCALAR_P (mem1
) && MEM_IN_STRUCT_P (mem2
)
1865 && !varies_p (mem1_addr
, 1) && varies_p (mem2_addr
, 1))
1866 /* MEM1 is a scalar at a fixed address; MEM2 is a struct at a
1870 if (MEM_IN_STRUCT_P (mem1
) && MEM_SCALAR_P (mem2
)
1871 && varies_p (mem1_addr
, 1) && !varies_p (mem2_addr
, 1))
1872 /* MEM2 is a scalar at a fixed address; MEM1 is a struct at a
1879 /* Returns nonzero if something about the mode or address format MEM1
1880 indicates that it might well alias *anything*. */
1883 aliases_everything_p (rtx mem
)
1885 if (GET_CODE (XEXP (mem
, 0)) == AND
)
1886 /* If the address is an AND, it's very hard to know at what it is
1887 actually pointing. */
1893 /* Return true if we can determine that the fields referenced cannot
1894 overlap for any pair of objects. */
1897 nonoverlapping_component_refs_p (tree x
, tree y
)
1899 tree fieldx
, fieldy
, typex
, typey
, orig_y
;
1903 /* The comparison has to be done at a common type, since we don't
1904 know how the inheritance hierarchy works. */
1908 fieldx
= TREE_OPERAND (x
, 1);
1909 typex
= DECL_FIELD_CONTEXT (fieldx
);
1914 fieldy
= TREE_OPERAND (y
, 1);
1915 typey
= DECL_FIELD_CONTEXT (fieldy
);
1920 y
= TREE_OPERAND (y
, 0);
1922 while (y
&& TREE_CODE (y
) == COMPONENT_REF
);
1924 x
= TREE_OPERAND (x
, 0);
1926 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
1928 /* Never found a common type. */
1932 /* If we're left with accessing different fields of a structure,
1934 if (TREE_CODE (typex
) == RECORD_TYPE
1935 && fieldx
!= fieldy
)
1938 /* The comparison on the current field failed. If we're accessing
1939 a very nested structure, look at the next outer level. */
1940 x
= TREE_OPERAND (x
, 0);
1941 y
= TREE_OPERAND (y
, 0);
1944 && TREE_CODE (x
) == COMPONENT_REF
1945 && TREE_CODE (y
) == COMPONENT_REF
);
1950 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
1953 decl_for_component_ref (tree x
)
1957 x
= TREE_OPERAND (x
, 0);
1959 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
1961 return x
&& DECL_P (x
) ? x
: NULL_TREE
;
1964 /* Walk up the COMPONENT_REF list and adjust OFFSET to compensate for the
1965 offset of the field reference. */
1968 adjust_offset_for_component_ref (tree x
, rtx offset
)
1970 HOST_WIDE_INT ioffset
;
1975 ioffset
= INTVAL (offset
);
1978 tree offset
= component_ref_field_offset (x
);
1979 tree field
= TREE_OPERAND (x
, 1);
1981 if (! host_integerp (offset
, 1))
1983 ioffset
+= (tree_low_cst (offset
, 1)
1984 + (tree_low_cst (DECL_FIELD_BIT_OFFSET (field
), 1)
1987 x
= TREE_OPERAND (x
, 0);
1989 while (x
&& TREE_CODE (x
) == COMPONENT_REF
);
1991 return GEN_INT (ioffset
);
1994 /* Return nonzero if we can determine the exprs corresponding to memrefs
1995 X and Y and they do not overlap. */
1998 nonoverlapping_memrefs_p (rtx x
, rtx y
)
2000 tree exprx
= MEM_EXPR (x
), expry
= MEM_EXPR (y
);
2003 rtx moffsetx
, moffsety
;
2004 HOST_WIDE_INT offsetx
= 0, offsety
= 0, sizex
, sizey
, tem
;
2006 /* Unless both have exprs, we can't tell anything. */
2007 if (exprx
== 0 || expry
== 0)
2010 /* If both are field references, we may be able to determine something. */
2011 if (TREE_CODE (exprx
) == COMPONENT_REF
2012 && TREE_CODE (expry
) == COMPONENT_REF
2013 && nonoverlapping_component_refs_p (exprx
, expry
))
2016 /* If the field reference test failed, look at the DECLs involved. */
2017 moffsetx
= MEM_OFFSET (x
);
2018 if (TREE_CODE (exprx
) == COMPONENT_REF
)
2020 tree t
= decl_for_component_ref (exprx
);
2023 moffsetx
= adjust_offset_for_component_ref (exprx
, moffsetx
);
2026 else if (INDIRECT_REF_P (exprx
))
2028 exprx
= TREE_OPERAND (exprx
, 0);
2029 if (flag_argument_noalias
< 2
2030 || TREE_CODE (exprx
) != PARM_DECL
)
2034 moffsety
= MEM_OFFSET (y
);
2035 if (TREE_CODE (expry
) == COMPONENT_REF
)
2037 tree t
= decl_for_component_ref (expry
);
2040 moffsety
= adjust_offset_for_component_ref (expry
, moffsety
);
2043 else if (INDIRECT_REF_P (expry
))
2045 expry
= TREE_OPERAND (expry
, 0);
2046 if (flag_argument_noalias
< 2
2047 || TREE_CODE (expry
) != PARM_DECL
)
2051 if (! DECL_P (exprx
) || ! DECL_P (expry
))
2054 rtlx
= DECL_RTL (exprx
);
2055 rtly
= DECL_RTL (expry
);
2057 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
2058 can't overlap unless they are the same because we never reuse that part
2059 of the stack frame used for locals for spilled pseudos. */
2060 if ((!MEM_P (rtlx
) || !MEM_P (rtly
))
2061 && ! rtx_equal_p (rtlx
, rtly
))
2064 /* Get the base and offsets of both decls. If either is a register, we
2065 know both are and are the same, so use that as the base. The only
2066 we can avoid overlap is if we can deduce that they are nonoverlapping
2067 pieces of that decl, which is very rare. */
2068 basex
= MEM_P (rtlx
) ? XEXP (rtlx
, 0) : rtlx
;
2069 if (GET_CODE (basex
) == PLUS
&& GET_CODE (XEXP (basex
, 1)) == CONST_INT
)
2070 offsetx
= INTVAL (XEXP (basex
, 1)), basex
= XEXP (basex
, 0);
2072 basey
= MEM_P (rtly
) ? XEXP (rtly
, 0) : rtly
;
2073 if (GET_CODE (basey
) == PLUS
&& GET_CODE (XEXP (basey
, 1)) == CONST_INT
)
2074 offsety
= INTVAL (XEXP (basey
, 1)), basey
= XEXP (basey
, 0);
2076 /* If the bases are different, we know they do not overlap if both
2077 are constants or if one is a constant and the other a pointer into the
2078 stack frame. Otherwise a different base means we can't tell if they
2080 if (! rtx_equal_p (basex
, basey
))
2081 return ((CONSTANT_P (basex
) && CONSTANT_P (basey
))
2082 || (CONSTANT_P (basex
) && REG_P (basey
)
2083 && REGNO_PTR_FRAME_P (REGNO (basey
)))
2084 || (CONSTANT_P (basey
) && REG_P (basex
)
2085 && REGNO_PTR_FRAME_P (REGNO (basex
))));
2087 sizex
= (!MEM_P (rtlx
) ? (int) GET_MODE_SIZE (GET_MODE (rtlx
))
2088 : MEM_SIZE (rtlx
) ? INTVAL (MEM_SIZE (rtlx
))
2090 sizey
= (!MEM_P (rtly
) ? (int) GET_MODE_SIZE (GET_MODE (rtly
))
2091 : MEM_SIZE (rtly
) ? INTVAL (MEM_SIZE (rtly
)) :
2094 /* If we have an offset for either memref, it can update the values computed
2097 offsetx
+= INTVAL (moffsetx
), sizex
-= INTVAL (moffsetx
);
2099 offsety
+= INTVAL (moffsety
), sizey
-= INTVAL (moffsety
);
2101 /* If a memref has both a size and an offset, we can use the smaller size.
2102 We can't do this if the offset isn't known because we must view this
2103 memref as being anywhere inside the DECL's MEM. */
2104 if (MEM_SIZE (x
) && moffsetx
)
2105 sizex
= INTVAL (MEM_SIZE (x
));
2106 if (MEM_SIZE (y
) && moffsety
)
2107 sizey
= INTVAL (MEM_SIZE (y
));
2109 /* Put the values of the memref with the lower offset in X's values. */
2110 if (offsetx
> offsety
)
2112 tem
= offsetx
, offsetx
= offsety
, offsety
= tem
;
2113 tem
= sizex
, sizex
= sizey
, sizey
= tem
;
2116 /* If we don't know the size of the lower-offset value, we can't tell
2117 if they conflict. Otherwise, we do the test. */
2118 return sizex
>= 0 && offsety
>= offsetx
+ sizex
;
2121 /* True dependence: X is read after store in MEM takes place. */
2124 true_dependence (rtx mem
, enum machine_mode mem_mode
, rtx x
,
2125 int (*varies
) (rtx
, int))
2127 rtx x_addr
, mem_addr
;
2130 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2133 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2134 This is used in epilogue deallocation functions. */
2135 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2137 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2140 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
2143 /* Read-only memory is by definition never modified, and therefore can't
2144 conflict with anything. We don't expect to find read-only set on MEM,
2145 but stupid user tricks can produce them, so don't die. */
2146 if (MEM_READONLY_P (x
))
2149 if (nonoverlapping_memrefs_p (mem
, x
))
2152 if (mem_mode
== VOIDmode
)
2153 mem_mode
= GET_MODE (mem
);
2155 x_addr
= get_addr (XEXP (x
, 0));
2156 mem_addr
= get_addr (XEXP (mem
, 0));
2158 base
= find_base_term (x_addr
);
2159 if (base
&& (GET_CODE (base
) == LABEL_REF
2160 || (GET_CODE (base
) == SYMBOL_REF
2161 && CONSTANT_POOL_ADDRESS_P (base
))))
2164 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
), mem_mode
))
2167 x_addr
= canon_rtx (x_addr
);
2168 mem_addr
= canon_rtx (mem_addr
);
2170 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
2171 SIZE_FOR_MODE (x
), x_addr
, 0))
2174 if (aliases_everything_p (x
))
2177 /* We cannot use aliases_everything_p to test MEM, since we must look
2178 at MEM_MODE, rather than GET_MODE (MEM). */
2179 if (mem_mode
== QImode
|| GET_CODE (mem_addr
) == AND
)
2182 /* In true_dependence we also allow BLKmode to alias anything. Why
2183 don't we do this in anti_dependence and output_dependence? */
2184 if (mem_mode
== BLKmode
|| GET_MODE (x
) == BLKmode
)
2187 return ! fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
2191 /* Canonical true dependence: X is read after store in MEM takes place.
2192 Variant of true_dependence which assumes MEM has already been
2193 canonicalized (hence we no longer do that here).
2194 The mem_addr argument has been added, since true_dependence computed
2195 this value prior to canonicalizing. */
2198 canon_true_dependence (rtx mem
, enum machine_mode mem_mode
, rtx mem_addr
,
2199 rtx x
, int (*varies
) (rtx
, int))
2203 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2206 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2207 This is used in epilogue deallocation functions. */
2208 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2210 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2213 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
2216 /* Read-only memory is by definition never modified, and therefore can't
2217 conflict with anything. We don't expect to find read-only set on MEM,
2218 but stupid user tricks can produce them, so don't die. */
2219 if (MEM_READONLY_P (x
))
2222 if (nonoverlapping_memrefs_p (x
, mem
))
2225 x_addr
= get_addr (XEXP (x
, 0));
2227 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
), mem_mode
))
2230 x_addr
= canon_rtx (x_addr
);
2231 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode
), mem_addr
,
2232 SIZE_FOR_MODE (x
), x_addr
, 0))
2235 if (aliases_everything_p (x
))
2238 /* We cannot use aliases_everything_p to test MEM, since we must look
2239 at MEM_MODE, rather than GET_MODE (MEM). */
2240 if (mem_mode
== QImode
|| GET_CODE (mem_addr
) == AND
)
2243 /* In true_dependence we also allow BLKmode to alias anything. Why
2244 don't we do this in anti_dependence and output_dependence? */
2245 if (mem_mode
== BLKmode
|| GET_MODE (x
) == BLKmode
)
2248 return ! fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
2252 /* Returns nonzero if a write to X might alias a previous read from
2253 (or, if WRITEP is nonzero, a write to) MEM. */
2256 write_dependence_p (rtx mem
, rtx x
, int writep
)
2258 rtx x_addr
, mem_addr
;
2262 if (MEM_VOLATILE_P (x
) && MEM_VOLATILE_P (mem
))
2265 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2266 This is used in epilogue deallocation functions. */
2267 if (GET_MODE (x
) == BLKmode
&& GET_CODE (XEXP (x
, 0)) == SCRATCH
)
2269 if (GET_MODE (mem
) == BLKmode
&& GET_CODE (XEXP (mem
, 0)) == SCRATCH
)
2272 if (DIFFERENT_ALIAS_SETS_P (x
, mem
))
2275 /* A read from read-only memory can't conflict with read-write memory. */
2276 if (!writep
&& MEM_READONLY_P (mem
))
2279 if (nonoverlapping_memrefs_p (x
, mem
))
2282 x_addr
= get_addr (XEXP (x
, 0));
2283 mem_addr
= get_addr (XEXP (mem
, 0));
2287 base
= find_base_term (mem_addr
);
2288 if (base
&& (GET_CODE (base
) == LABEL_REF
2289 || (GET_CODE (base
) == SYMBOL_REF
2290 && CONSTANT_POOL_ADDRESS_P (base
))))
2294 if (! base_alias_check (x_addr
, mem_addr
, GET_MODE (x
),
2298 x_addr
= canon_rtx (x_addr
);
2299 mem_addr
= canon_rtx (mem_addr
);
2301 if (!memrefs_conflict_p (SIZE_FOR_MODE (mem
), mem_addr
,
2302 SIZE_FOR_MODE (x
), x_addr
, 0))
2306 = fixed_scalar_and_varying_struct_p (mem
, x
, mem_addr
, x_addr
,
2309 return (!(fixed_scalar
== mem
&& !aliases_everything_p (x
))
2310 && !(fixed_scalar
== x
&& !aliases_everything_p (mem
)));
2313 /* Anti dependence: X is written after read in MEM takes place. */
2316 anti_dependence (rtx mem
, rtx x
)
2318 return write_dependence_p (mem
, x
, /*writep=*/0);
2321 /* Output dependence: X is written after store in MEM takes place. */
2324 output_dependence (rtx mem
, rtx x
)
2326 return write_dependence_p (mem
, x
, /*writep=*/1);
2329 /* A subroutine of nonlocal_mentioned_p, returns 1 if *LOC mentions
2330 something which is not local to the function and is not constant. */
2333 nonlocal_mentioned_p_1 (rtx
*loc
, void *data ATTRIBUTE_UNUSED
)
2342 switch (GET_CODE (x
))
2345 if (REG_P (SUBREG_REG (x
)))
2347 /* Global registers are not local. */
2348 if (REGNO (SUBREG_REG (x
)) < FIRST_PSEUDO_REGISTER
2349 && global_regs
[subreg_regno (x
)])
2357 /* Global registers are not local. */
2358 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2373 /* Constants in the function's constants pool are constant. */
2374 if (CONSTANT_POOL_ADDRESS_P (x
))
2379 /* Non-constant calls and recursion are not local. */
2383 /* Be overly conservative and consider any volatile memory
2384 reference as not local. */
2385 if (MEM_VOLATILE_P (x
))
2387 base
= find_base_term (XEXP (x
, 0));
2390 /* A Pmode ADDRESS could be a reference via the structure value
2391 address or static chain. Such memory references are nonlocal.
2393 Thus, we have to examine the contents of the ADDRESS to find
2394 out if this is a local reference or not. */
2395 if (GET_CODE (base
) == ADDRESS
2396 && GET_MODE (base
) == Pmode
2397 && (XEXP (base
, 0) == stack_pointer_rtx
2398 || XEXP (base
, 0) == arg_pointer_rtx
2399 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2400 || XEXP (base
, 0) == hard_frame_pointer_rtx
2402 || XEXP (base
, 0) == frame_pointer_rtx
))
2404 /* Constants in the function's constant pool are constant. */
2405 if (GET_CODE (base
) == SYMBOL_REF
&& CONSTANT_POOL_ADDRESS_P (base
))
2410 case UNSPEC_VOLATILE
:
2415 if (MEM_VOLATILE_P (x
))
2427 /* Returns nonzero if X might mention something which is not
2428 local to the function and is not constant. */
2431 nonlocal_mentioned_p (rtx x
)
2437 if (! CONST_OR_PURE_CALL_P (x
))
2439 x
= CALL_INSN_FUNCTION_USAGE (x
);
2447 return for_each_rtx (&x
, nonlocal_mentioned_p_1
, NULL
);
2450 /* A subroutine of nonlocal_referenced_p, returns 1 if *LOC references
2451 something which is not local to the function and is not constant. */
2454 nonlocal_referenced_p_1 (rtx
*loc
, void *data ATTRIBUTE_UNUSED
)
2461 switch (GET_CODE (x
))
2467 return nonlocal_mentioned_p (x
);
2470 /* Non-constant calls and recursion are not local. */
2474 if (nonlocal_mentioned_p (SET_SRC (x
)))
2477 if (MEM_P (SET_DEST (x
)))
2478 return nonlocal_mentioned_p (XEXP (SET_DEST (x
), 0));
2480 /* If the destination is anything other than a CC0, PC,
2481 MEM, REG, or a SUBREG of a REG that occupies all of
2482 the REG, then X references nonlocal memory if it is
2483 mentioned in the destination. */
2484 if (GET_CODE (SET_DEST (x
)) != CC0
2485 && GET_CODE (SET_DEST (x
)) != PC
2486 && !REG_P (SET_DEST (x
))
2487 && ! (GET_CODE (SET_DEST (x
)) == SUBREG
2488 && REG_P (SUBREG_REG (SET_DEST (x
)))
2489 && (((GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (x
))))
2490 + (UNITS_PER_WORD
- 1)) / UNITS_PER_WORD
)
2491 == ((GET_MODE_SIZE (GET_MODE (SET_DEST (x
)))
2492 + (UNITS_PER_WORD
- 1)) / UNITS_PER_WORD
))))
2493 return nonlocal_mentioned_p (SET_DEST (x
));
2497 if (MEM_P (XEXP (x
, 0)))
2498 return nonlocal_mentioned_p (XEXP (XEXP (x
, 0), 0));
2502 return nonlocal_mentioned_p (XEXP (x
, 0));
2505 case UNSPEC_VOLATILE
:
2509 if (MEM_VOLATILE_P (x
))
2521 /* Returns nonzero if X might reference something which is not
2522 local to the function and is not constant. */
2525 nonlocal_referenced_p (rtx x
)
2531 if (! CONST_OR_PURE_CALL_P (x
))
2533 x
= CALL_INSN_FUNCTION_USAGE (x
);
2541 return for_each_rtx (&x
, nonlocal_referenced_p_1
, NULL
);
2544 /* A subroutine of nonlocal_set_p, returns 1 if *LOC sets
2545 something which is not local to the function and is not constant. */
2548 nonlocal_set_p_1 (rtx
*loc
, void *data ATTRIBUTE_UNUSED
)
2555 switch (GET_CODE (x
))
2558 /* Non-constant calls and recursion are not local. */
2567 return nonlocal_mentioned_p (XEXP (x
, 0));
2570 if (nonlocal_mentioned_p (SET_DEST (x
)))
2572 return nonlocal_set_p (SET_SRC (x
));
2575 return nonlocal_mentioned_p (XEXP (x
, 0));
2581 case UNSPEC_VOLATILE
:
2585 if (MEM_VOLATILE_P (x
))
2597 /* Returns nonzero if X might set something which is not
2598 local to the function and is not constant. */
2601 nonlocal_set_p (rtx x
)
2607 if (! CONST_OR_PURE_CALL_P (x
))
2609 x
= CALL_INSN_FUNCTION_USAGE (x
);
2617 return for_each_rtx (&x
, nonlocal_set_p_1
, NULL
);
2620 /* Mark the function if it is pure or constant. */
2623 mark_constant_function (void)
2626 int nonlocal_memory_referenced
;
2628 if (TREE_READONLY (current_function_decl
)
2629 || DECL_IS_PURE (current_function_decl
)
2630 || TREE_THIS_VOLATILE (current_function_decl
)
2631 || current_function_has_nonlocal_goto
2632 || !targetm
.binds_local_p (current_function_decl
))
2635 /* A loop might not return which counts as a side effect. */
2636 if (mark_dfs_back_edges ())
2639 nonlocal_memory_referenced
= 0;
2641 init_alias_analysis ();
2643 /* Determine if this is a constant or pure function. */
2645 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
2647 if (! INSN_P (insn
))
2650 if (nonlocal_set_p (insn
) || global_reg_mentioned_p (insn
)
2651 || volatile_refs_p (PATTERN (insn
)))
2654 if (! nonlocal_memory_referenced
)
2655 nonlocal_memory_referenced
= nonlocal_referenced_p (insn
);
2658 end_alias_analysis ();
2660 /* Mark the function. */
2664 else if (nonlocal_memory_referenced
)
2666 cgraph_rtl_info (current_function_decl
)->pure_function
= 1;
2667 DECL_IS_PURE (current_function_decl
) = 1;
2671 cgraph_rtl_info (current_function_decl
)->const_function
= 1;
2672 TREE_READONLY (current_function_decl
) = 1;
2678 init_alias_once (void)
2682 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2683 /* Check whether this register can hold an incoming pointer
2684 argument. FUNCTION_ARG_REGNO_P tests outgoing register
2685 numbers, so translate if necessary due to register windows. */
2686 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i
))
2687 && HARD_REGNO_MODE_OK (i
, Pmode
))
2688 static_reg_base_value
[i
]
2689 = gen_rtx_ADDRESS (VOIDmode
, gen_rtx_REG (Pmode
, i
));
2691 static_reg_base_value
[STACK_POINTER_REGNUM
]
2692 = gen_rtx_ADDRESS (Pmode
, stack_pointer_rtx
);
2693 static_reg_base_value
[ARG_POINTER_REGNUM
]
2694 = gen_rtx_ADDRESS (Pmode
, arg_pointer_rtx
);
2695 static_reg_base_value
[FRAME_POINTER_REGNUM
]
2696 = gen_rtx_ADDRESS (Pmode
, frame_pointer_rtx
);
2697 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2698 static_reg_base_value
[HARD_FRAME_POINTER_REGNUM
]
2699 = gen_rtx_ADDRESS (Pmode
, hard_frame_pointer_rtx
);
2703 /* Set MEMORY_MODIFIED when X modifies DATA (that is assumed
2704 to be memory reference. */
2705 static bool memory_modified
;
2707 memory_modified_1 (rtx x
, rtx pat ATTRIBUTE_UNUSED
, void *data
)
2711 if (anti_dependence (x
, (rtx
)data
) || output_dependence (x
, (rtx
)data
))
2712 memory_modified
= true;
2717 /* Return true when INSN possibly modify memory contents of MEM
2718 (i.e. address can be modified). */
2720 memory_modified_in_insn_p (rtx mem
, rtx insn
)
2724 memory_modified
= false;
2725 note_stores (PATTERN (insn
), memory_modified_1
, mem
);
2726 return memory_modified
;
2729 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
2733 init_alias_analysis (void)
2735 unsigned int maxreg
= max_reg_num ();
2741 timevar_push (TV_ALIAS_ANALYSIS
);
2743 reg_known_value_size
= maxreg
- FIRST_PSEUDO_REGISTER
;
2744 reg_known_value
= ggc_calloc (reg_known_value_size
, sizeof (rtx
));
2745 reg_known_equiv_p
= xcalloc (reg_known_value_size
, sizeof (bool));
2747 /* Overallocate reg_base_value to allow some growth during loop
2748 optimization. Loop unrolling can create a large number of
2750 if (old_reg_base_value
)
2752 reg_base_value
= old_reg_base_value
;
2753 /* If varray gets large zeroing cost may get important. */
2754 if (VARRAY_SIZE (reg_base_value
) > 256
2755 && VARRAY_SIZE (reg_base_value
) > 4 * maxreg
)
2756 VARRAY_GROW (reg_base_value
, maxreg
);
2757 VARRAY_CLEAR (reg_base_value
);
2758 if (VARRAY_SIZE (reg_base_value
) < maxreg
)
2759 VARRAY_GROW (reg_base_value
, maxreg
);
2763 VARRAY_RTX_INIT (reg_base_value
, maxreg
, "reg_base_value");
2766 new_reg_base_value
= xmalloc (maxreg
* sizeof (rtx
));
2767 reg_seen
= xmalloc (maxreg
);
2769 /* The basic idea is that each pass through this loop will use the
2770 "constant" information from the previous pass to propagate alias
2771 information through another level of assignments.
2773 This could get expensive if the assignment chains are long. Maybe
2774 we should throttle the number of iterations, possibly based on
2775 the optimization level or flag_expensive_optimizations.
2777 We could propagate more information in the first pass by making use
2778 of REG_N_SETS to determine immediately that the alias information
2779 for a pseudo is "constant".
2781 A program with an uninitialized variable can cause an infinite loop
2782 here. Instead of doing a full dataflow analysis to detect such problems
2783 we just cap the number of iterations for the loop.
2785 The state of the arrays for the set chain in question does not matter
2786 since the program has undefined behavior. */
2791 /* Assume nothing will change this iteration of the loop. */
2794 /* We want to assign the same IDs each iteration of this loop, so
2795 start counting from zero each iteration of the loop. */
2798 /* We're at the start of the function each iteration through the
2799 loop, so we're copying arguments. */
2800 copying_arguments
= true;
2802 /* Wipe the potential alias information clean for this pass. */
2803 memset (new_reg_base_value
, 0, maxreg
* sizeof (rtx
));
2805 /* Wipe the reg_seen array clean. */
2806 memset (reg_seen
, 0, maxreg
);
2808 /* Mark all hard registers which may contain an address.
2809 The stack, frame and argument pointers may contain an address.
2810 An argument register which can hold a Pmode value may contain
2811 an address even if it is not in BASE_REGS.
2813 The address expression is VOIDmode for an argument and
2814 Pmode for other registers. */
2816 memcpy (new_reg_base_value
, static_reg_base_value
,
2817 FIRST_PSEUDO_REGISTER
* sizeof (rtx
));
2819 /* Walk the insns adding values to the new_reg_base_value array. */
2820 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
2826 #if defined (HAVE_prologue) || defined (HAVE_epilogue)
2827 /* The prologue/epilogue insns are not threaded onto the
2828 insn chain until after reload has completed. Thus,
2829 there is no sense wasting time checking if INSN is in
2830 the prologue/epilogue until after reload has completed. */
2831 if (reload_completed
2832 && prologue_epilogue_contains (insn
))
2836 /* If this insn has a noalias note, process it, Otherwise,
2837 scan for sets. A simple set will have no side effects
2838 which could change the base value of any other register. */
2840 if (GET_CODE (PATTERN (insn
)) == SET
2841 && REG_NOTES (insn
) != 0
2842 && find_reg_note (insn
, REG_NOALIAS
, NULL_RTX
))
2843 record_set (SET_DEST (PATTERN (insn
)), NULL_RTX
, NULL
);
2845 note_stores (PATTERN (insn
), record_set
, NULL
);
2847 set
= single_set (insn
);
2850 && REG_P (SET_DEST (set
))
2851 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
)
2853 unsigned int regno
= REGNO (SET_DEST (set
));
2854 rtx src
= SET_SRC (set
);
2857 if (REG_NOTES (insn
) != 0
2858 && (((note
= find_reg_note (insn
, REG_EQUAL
, 0)) != 0
2859 && REG_N_SETS (regno
) == 1)
2860 || (note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) != 0)
2861 && GET_CODE (XEXP (note
, 0)) != EXPR_LIST
2862 && ! rtx_varies_p (XEXP (note
, 0), 1)
2863 && ! reg_overlap_mentioned_p (SET_DEST (set
),
2866 set_reg_known_value (regno
, XEXP (note
, 0));
2867 set_reg_known_equiv_p (regno
,
2868 REG_NOTE_KIND (note
) == REG_EQUIV
);
2870 else if (REG_N_SETS (regno
) == 1
2871 && GET_CODE (src
) == PLUS
2872 && REG_P (XEXP (src
, 0))
2873 && (t
= get_reg_known_value (REGNO (XEXP (src
, 0))))
2874 && GET_CODE (XEXP (src
, 1)) == CONST_INT
)
2876 t
= plus_constant (t
, INTVAL (XEXP (src
, 1)));
2877 set_reg_known_value (regno
, t
);
2878 set_reg_known_equiv_p (regno
, 0);
2880 else if (REG_N_SETS (regno
) == 1
2881 && ! rtx_varies_p (src
, 1))
2883 set_reg_known_value (regno
, src
);
2884 set_reg_known_equiv_p (regno
, 0);
2888 else if (NOTE_P (insn
)
2889 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_FUNCTION_BEG
)
2890 copying_arguments
= false;
2893 /* Now propagate values from new_reg_base_value to reg_base_value. */
2894 gcc_assert (maxreg
== (unsigned int) max_reg_num());
2896 for (ui
= 0; ui
< maxreg
; ui
++)
2898 if (new_reg_base_value
[ui
]
2899 && new_reg_base_value
[ui
] != VARRAY_RTX (reg_base_value
, ui
)
2900 && ! rtx_equal_p (new_reg_base_value
[ui
],
2901 VARRAY_RTX (reg_base_value
, ui
)))
2903 VARRAY_RTX (reg_base_value
, ui
) = new_reg_base_value
[ui
];
2908 while (changed
&& ++pass
< MAX_ALIAS_LOOP_PASSES
);
2910 /* Fill in the remaining entries. */
2911 for (i
= 0; i
< (int)reg_known_value_size
; i
++)
2912 if (reg_known_value
[i
] == 0)
2913 reg_known_value
[i
] = regno_reg_rtx
[i
+ FIRST_PSEUDO_REGISTER
];
2915 /* Simplify the reg_base_value array so that no register refers to
2916 another register, except to special registers indirectly through
2917 ADDRESS expressions.
2919 In theory this loop can take as long as O(registers^2), but unless
2920 there are very long dependency chains it will run in close to linear
2923 This loop may not be needed any longer now that the main loop does
2924 a better job at propagating alias information. */
2930 for (ui
= 0; ui
< maxreg
; ui
++)
2932 rtx base
= VARRAY_RTX (reg_base_value
, ui
);
2933 if (base
&& REG_P (base
))
2935 unsigned int base_regno
= REGNO (base
);
2936 if (base_regno
== ui
) /* register set from itself */
2937 VARRAY_RTX (reg_base_value
, ui
) = 0;
2939 VARRAY_RTX (reg_base_value
, ui
)
2940 = VARRAY_RTX (reg_base_value
, base_regno
);
2945 while (changed
&& pass
< MAX_ALIAS_LOOP_PASSES
);
2948 free (new_reg_base_value
);
2949 new_reg_base_value
= 0;
2952 timevar_pop (TV_ALIAS_ANALYSIS
);
2956 end_alias_analysis (void)
2958 old_reg_base_value
= reg_base_value
;
2959 ggc_free (reg_known_value
);
2960 reg_known_value
= 0;
2961 reg_known_value_size
= 0;
2962 free (reg_known_equiv_p
);
2963 reg_known_equiv_p
= 0;
2964 if (alias_invariant
)
2966 ggc_free (alias_invariant
);
2967 alias_invariant
= 0;
2968 alias_invariant_size
= 0;
2972 /* Do control and data flow analysis; write some of the results to the
2975 rest_of_handle_cfg (void)
2978 dump_flow_info (dump_file
);
2980 cleanup_cfg (CLEANUP_EXPENSIVE
2981 | (flag_thread_jumps
? CLEANUP_THREADING
: 0));
2983 /* It may make more sense to mark constant functions after dead code is
2984 eliminated by life_analysis, but we need to do it early, as -fprofile-arcs
2985 may insert code making function non-constant, but we still must consider
2986 it as constant, otherwise -fbranch-probabilities will not read data back.
2988 life_analysis rarely eliminates modification of external memory.
2990 FIXME: now with tree based profiling we are in the trap described above
2991 again. It seems to be easiest to disable the optimization for time
2992 being before the problem is either solved by moving the transformation
2993 to the IPA level (we need the CFG for this) or the very early optimization
2994 passes are made to ignore the const/pure flags so code does not change. */
2996 && (!flag_tree_based_profiling
2997 || (!profile_arc_flag
&& !flag_branch_probabilities
)))
2999 /* Alias analysis depends on this information and mark_constant_function
3000 depends on alias analysis. */
3001 reg_scan (get_insns (), max_reg_num ());
3002 mark_constant_function ();
3006 struct tree_opt_pass pass_cfg
=
3010 rest_of_handle_cfg
, /* execute */
3013 0, /* static_pass_number */
3014 TV_FLOW
, /* tv_id */
3015 0, /* properties_required */
3016 0, /* properties_provided */
3017 0, /* properties_destroyed */
3018 0, /* todo_flags_start */
3019 TODO_dump_func
, /* todo_flags_finish */
3024 #include "gt-alias.h"