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"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
39 #include "splay-tree.h"
41 #include "langhooks.h"
47 /* The alias sets assigned to MEMs assist the back-end in determining
48 which MEMs can alias which other MEMs. In general, two MEMs in
49 different alias sets cannot alias each other, with one important
50 exception. Consider something like:
52 struct S { int i; double d; };
54 a store to an `S' can alias something of either type `int' or type
55 `double'. (However, a store to an `int' cannot alias a `double'
56 and vice versa.) We indicate this via a tree structure that looks
64 (The arrows are directed and point downwards.)
65 In this situation we say the alias set for `struct S' is the
66 `superset' and that those for `int' and `double' are `subsets'.
68 To see whether two alias sets can point to the same memory, we must
69 see if either alias set is a subset of the other. We need not trace
70 past immediate descendants, however, since we propagate all
71 grandchildren up one level.
73 Alias set zero is implicitly a superset of all other alias sets.
74 However, this is no actual entry for alias set zero. It is an
75 error to attempt to explicitly construct a subset of zero. */
77 struct alias_set_entry GTY(())
79 /* The alias set number, as stored in MEM_ALIAS_SET. */
80 HOST_WIDE_INT alias_set;
82 /* The children of the alias set. These are not just the immediate
83 children, but, in fact, all descendants. So, if we have:
85 struct T { struct S s; float f; }
87 continuing our example above, the children here will be all of
88 `int', `double', `float', and `struct S'. */
89 splay_tree GTY((param1_is (int), param2_is (int))) children;
91 /* Nonzero if would have a child of zero: this effectively makes this
92 alias set the same as alias set zero. */
95 typedef struct alias_set_entry *alias_set_entry;
97 static int rtx_equal_for_memref_p (rtx, rtx);
98 static rtx find_symbolic_term (rtx);
99 static int memrefs_conflict_p (int, rtx, int, rtx, HOST_WIDE_INT);
100 static void record_set (rtx, rtx, void *);
101 static int base_alias_check (rtx, rtx, enum machine_mode,
103 static rtx find_base_value (rtx);
104 static int mems_in_disjoint_alias_sets_p (rtx, rtx);
105 static int insert_subset_children (splay_tree_node, void*);
106 static tree find_base_decl (tree);
107 static alias_set_entry get_alias_set_entry (HOST_WIDE_INT);
108 static rtx fixed_scalar_and_varying_struct_p (rtx, rtx, rtx, rtx,
110 static int aliases_everything_p (rtx);
111 static bool nonoverlapping_component_refs_p (tree, tree);
112 static tree decl_for_component_ref (tree);
113 static rtx adjust_offset_for_component_ref (tree, rtx);
114 static int nonoverlapping_memrefs_p (rtx, rtx);
115 static int write_dependence_p (rtx, rtx, int, int);
117 static int nonlocal_mentioned_p_1 (rtx *, void *);
118 static int nonlocal_mentioned_p (rtx);
119 static int nonlocal_referenced_p_1 (rtx *, void *);
120 static int nonlocal_referenced_p (rtx);
121 static int nonlocal_set_p_1 (rtx *, void *);
122 static int nonlocal_set_p (rtx);
123 static void memory_modified_1 (rtx, rtx, void *);
125 /* Set up all info needed to perform alias analysis on memory references. */
127 /* Returns the size in bytes of the mode of X. */
128 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
130 /* Returns nonzero if MEM1 and MEM2 do not alias because they are in
131 different alias sets. We ignore alias sets in functions making use
132 of variable arguments because the va_arg macros on some systems are
134 #define DIFFERENT_ALIAS_SETS_P(MEM1, MEM2) \
135 mems_in_disjoint_alias_sets_p (MEM1, MEM2)
137 /* Cap the number of passes we make over the insns propagating alias
138 information through set chains. 10 is a completely arbitrary choice. */
139 #define MAX_ALIAS_LOOP_PASSES 10
141 /* reg_base_value[N] gives an address to which register N is related.
142 If all sets after the first add or subtract to the current value
143 or otherwise modify it so it does not point to a different top level
144 object, reg_base_value[N] is equal to the address part of the source
147 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
148 expressions represent certain special values: function arguments and
149 the stack, frame, and argument pointers.
151 The contents of an ADDRESS is not normally used, the mode of the
152 ADDRESS determines whether the ADDRESS is a function argument or some
153 other special value. Pointer equality, not rtx_equal_p, determines whether
154 two ADDRESS expressions refer to the same base address.
156 The only use of the contents of an ADDRESS is for determining if the
157 current function performs nonlocal memory memory references for the
158 purposes of marking the function as a constant function. */
160 static GTY(()) varray_type reg_base_value;
161 static rtx *new_reg_base_value;
163 /* We preserve the copy of old array around to avoid amount of garbage
164 produced. About 8% of garbage produced were attributed to this
166 static GTY((deletable (""))) varray_type old_reg_base_value;
168 /* Static hunks of RTL used by the aliasing code; these are initialized
169 once per function to avoid unnecessary RTL allocations. */
170 static GTY (()) rtx static_reg_base_value[FIRST_PSEUDO_REGISTER];
172 #define REG_BASE_VALUE(X) \
173 (reg_base_value && REGNO (X) < VARRAY_SIZE (reg_base_value) \
174 ? VARRAY_RTX (reg_base_value, REGNO (X)) : 0)
176 /* Vector of known invariant relationships between registers. Set in
177 loop unrolling. Indexed by register number, if nonzero the value
178 is an expression describing this register in terms of another.
180 The length of this array is REG_BASE_VALUE_SIZE.
182 Because this array contains only pseudo registers it has no effect
184 static rtx *alias_invariant;
185 unsigned int alias_invariant_size;
187 /* Vector indexed by N giving the initial (unchanging) value known for
188 pseudo-register N. This array is initialized in
189 init_alias_analysis, and does not change until end_alias_analysis
191 rtx *reg_known_value;
193 /* Indicates number of valid entries in reg_known_value. */
194 static unsigned int reg_known_value_size;
196 /* Vector recording for each reg_known_value whether it is due to a
197 REG_EQUIV note. Future passes (viz., reload) may replace the
198 pseudo with the equivalent expression and so we account for the
199 dependences that would be introduced if that happens.
201 The REG_EQUIV notes created in assign_parms may mention the arg
202 pointer, and there are explicit insns in the RTL that modify the
203 arg pointer. Thus we must ensure that such insns don't get
204 scheduled across each other because that would invalidate the
205 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
206 wrong, but solving the problem in the scheduler will likely give
207 better code, so we do it here. */
208 char *reg_known_equiv_p;
210 /* True when scanning insns from the start of the rtl to the
211 NOTE_INSN_FUNCTION_BEG note. */
212 static bool copying_arguments;
214 /* The splay-tree used to store the various alias set entries. */
215 static GTY ((param_is (struct alias_set_entry))) varray_type alias_sets;
217 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
218 such an entry, or NULL otherwise. */
220 static inline alias_set_entry
221 get_alias_set_entry (HOST_WIDE_INT alias_set)
223 return (alias_set_entry)VARRAY_GENERIC_PTR (alias_sets, alias_set);
226 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
227 the two MEMs cannot alias each other. */
230 mems_in_disjoint_alias_sets_p (rtx mem1, rtx mem2)
232 #ifdef ENABLE_CHECKING
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 if (! flag_strict_aliasing
241 && (MEM_ALIAS_SET (mem1) != 0 || MEM_ALIAS_SET (mem2) != 0))
245 return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1), MEM_ALIAS_SET (mem2));
248 /* Insert the NODE into the splay tree given by DATA. Used by
249 record_alias_subset via splay_tree_foreach. */
252 insert_subset_children (splay_tree_node node, void *data)
254 splay_tree_insert ((splay_tree) data, node->key, node->value);
259 /* Return 1 if the two specified alias sets may conflict. */
262 alias_sets_conflict_p (HOST_WIDE_INT set1, HOST_WIDE_INT set2)
266 /* If have no alias set information for one of the operands, we have
267 to assume it can alias anything. */
268 if (set1 == 0 || set2 == 0
269 /* If the two alias sets are the same, they may alias. */
273 /* See if the first alias set is a subset of the second. */
274 ase = get_alias_set_entry (set1);
276 && (ase->has_zero_child
277 || splay_tree_lookup (ase->children,
278 (splay_tree_key) set2)))
281 /* Now do the same, but with the alias sets reversed. */
282 ase = get_alias_set_entry (set2);
284 && (ase->has_zero_child
285 || splay_tree_lookup (ase->children,
286 (splay_tree_key) set1)))
289 /* The two alias sets are distinct and neither one is the
290 child of the other. Therefore, they cannot alias. */
294 /* Return 1 if the two specified alias sets might conflict, or if any subtype
295 of these alias sets might conflict. */
298 alias_sets_might_conflict_p (HOST_WIDE_INT set1, HOST_WIDE_INT set2)
300 if (set1 == 0 || set2 == 0 || set1 == set2)
307 /* Return 1 if TYPE is a RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE and has
308 has any readonly fields. If any of the fields have types that
309 contain readonly fields, return true as well. */
312 readonly_fields_p (tree type)
316 if (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
317 && TREE_CODE (type) != QUAL_UNION_TYPE)
320 for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field))
321 if (TREE_CODE (field) == FIELD_DECL
322 && (TREE_READONLY (field)
323 || readonly_fields_p (TREE_TYPE (field))))
329 /* Return 1 if any MEM object of type T1 will always conflict (using the
330 dependency routines in this file) with any MEM object of type T2.
331 This is used when allocating temporary storage. If T1 and/or T2 are
332 NULL_TREE, it means we know nothing about the storage. */
335 objects_must_conflict_p (tree t1, tree t2)
337 HOST_WIDE_INT set1, set2;
339 /* If neither has a type specified, we don't know if they'll conflict
340 because we may be using them to store objects of various types, for
341 example the argument and local variables areas of inlined functions. */
342 if (t1 == 0 && t2 == 0)
345 /* If one or the other has readonly fields or is readonly,
346 then they may not conflict. */
347 if ((t1 != 0 && readonly_fields_p (t1))
348 || (t2 != 0 && readonly_fields_p (t2))
349 || (t1 != 0 && lang_hooks.honor_readonly && TYPE_READONLY (t1))
350 || (t2 != 0 && lang_hooks.honor_readonly && TYPE_READONLY (t2)))
353 /* If they are the same type, they must conflict. */
355 /* Likewise if both are volatile. */
356 || (t1 != 0 && TYPE_VOLATILE (t1) && t2 != 0 && TYPE_VOLATILE (t2)))
359 set1 = t1 ? get_alias_set (t1) : 0;
360 set2 = t2 ? get_alias_set (t2) : 0;
362 /* Otherwise they conflict if they have no alias set or the same. We
363 can't simply use alias_sets_conflict_p here, because we must make
364 sure that every subtype of t1 will conflict with every subtype of
365 t2 for which a pair of subobjects of these respective subtypes
366 overlaps on the stack. */
367 return set1 == 0 || set2 == 0 || set1 == set2;
370 /* T is an expression with pointer type. Find the DECL on which this
371 expression is based. (For example, in `a[i]' this would be `a'.)
372 If there is no such DECL, or a unique decl cannot be determined,
373 NULL_TREE is returned. */
376 find_base_decl (tree t)
380 if (t == 0 || t == error_mark_node || ! POINTER_TYPE_P (TREE_TYPE (t)))
383 /* If this is a declaration, return it. */
384 if (TREE_CODE_CLASS (TREE_CODE (t)) == 'd')
387 /* Handle general expressions. It would be nice to deal with
388 COMPONENT_REFs here. If we could tell that `a' and `b' were the
389 same, then `a->f' and `b->f' are also the same. */
390 switch (TREE_CODE_CLASS (TREE_CODE (t)))
393 return find_base_decl (TREE_OPERAND (t, 0));
396 /* Return 0 if found in neither or both are the same. */
397 d0 = find_base_decl (TREE_OPERAND (t, 0));
398 d1 = find_base_decl (TREE_OPERAND (t, 1));
409 d0 = find_base_decl (TREE_OPERAND (t, 0));
410 d1 = find_base_decl (TREE_OPERAND (t, 1));
411 d2 = find_base_decl (TREE_OPERAND (t, 2));
413 /* Set any nonzero values from the last, then from the first. */
414 if (d1 == 0) d1 = d2;
415 if (d0 == 0) d0 = d1;
416 if (d1 == 0) d1 = d0;
417 if (d2 == 0) d2 = d1;
419 /* At this point all are nonzero or all are zero. If all three are the
420 same, return it. Otherwise, return zero. */
421 return (d0 == d1 && d1 == d2) ? d0 : 0;
428 /* Return 1 if all the nested component references handled by
429 get_inner_reference in T are such that we can address the object in T. */
432 can_address_p (tree t)
434 /* If we're at the end, it is vacuously addressable. */
435 if (! handled_component_p (t))
438 /* Bitfields are never addressable. */
439 else if (TREE_CODE (t) == BIT_FIELD_REF)
442 /* Fields are addressable unless they are marked as nonaddressable or
443 the containing type has alias set 0. */
444 else if (TREE_CODE (t) == COMPONENT_REF
445 && ! DECL_NONADDRESSABLE_P (TREE_OPERAND (t, 1))
446 && get_alias_set (TREE_TYPE (TREE_OPERAND (t, 0))) != 0
447 && can_address_p (TREE_OPERAND (t, 0)))
450 /* Likewise for arrays. */
451 else if ((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
452 && ! TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t, 0)))
453 && get_alias_set (TREE_TYPE (TREE_OPERAND (t, 0))) != 0
454 && can_address_p (TREE_OPERAND (t, 0)))
460 /* Return the alias set for T, which may be either a type or an
461 expression. Call language-specific routine for help, if needed. */
464 get_alias_set (tree t)
468 /* If we're not doing any alias analysis, just assume everything
469 aliases everything else. Also return 0 if this or its type is
471 if (! flag_strict_aliasing || t == error_mark_node
473 && (TREE_TYPE (t) == 0 || TREE_TYPE (t) == error_mark_node)))
476 /* We can be passed either an expression or a type. This and the
477 language-specific routine may make mutually-recursive calls to each other
478 to figure out what to do. At each juncture, we see if this is a tree
479 that the language may need to handle specially. First handle things that
484 tree placeholder_ptr = 0;
486 /* Remove any nops, then give the language a chance to do
487 something with this tree before we look at it. */
489 set = lang_hooks.get_alias_set (t);
493 /* First see if the actual object referenced is an INDIRECT_REF from a
494 restrict-qualified pointer or a "void *". Replace
495 PLACEHOLDER_EXPRs. */
496 while (TREE_CODE (inner) == PLACEHOLDER_EXPR
497 || handled_component_p (inner))
499 if (TREE_CODE (inner) == PLACEHOLDER_EXPR)
500 inner = find_placeholder (inner, &placeholder_ptr);
502 inner = TREE_OPERAND (inner, 0);
507 /* Check for accesses through restrict-qualified pointers. */
508 if (TREE_CODE (inner) == INDIRECT_REF)
510 tree decl = find_base_decl (TREE_OPERAND (inner, 0));
512 if (decl && DECL_POINTER_ALIAS_SET_KNOWN_P (decl))
514 /* If we haven't computed the actual alias set, do it now. */
515 if (DECL_POINTER_ALIAS_SET (decl) == -2)
517 /* No two restricted pointers can point at the same thing.
518 However, a restricted pointer can point at the same thing
519 as an unrestricted pointer, if that unrestricted pointer
520 is based on the restricted pointer. So, we make the
521 alias set for the restricted pointer a subset of the
522 alias set for the type pointed to by the type of the
524 HOST_WIDE_INT pointed_to_alias_set
525 = get_alias_set (TREE_TYPE (TREE_TYPE (decl)));
527 if (pointed_to_alias_set == 0)
528 /* It's not legal to make a subset of alias set zero. */
529 DECL_POINTER_ALIAS_SET (decl) = 0;
532 DECL_POINTER_ALIAS_SET (decl) = new_alias_set ();
533 record_alias_subset (pointed_to_alias_set,
534 DECL_POINTER_ALIAS_SET (decl));
538 /* We use the alias set indicated in the declaration. */
539 return DECL_POINTER_ALIAS_SET (decl);
542 /* If we have an INDIRECT_REF via a void pointer, we don't
543 know anything about what that might alias. */
544 else if (TREE_CODE (TREE_TYPE (inner)) == VOID_TYPE)
548 /* Otherwise, pick up the outermost object that we could have a pointer
549 to, processing conversion and PLACEHOLDER_EXPR as above. */
551 while (TREE_CODE (t) == PLACEHOLDER_EXPR
552 || (handled_component_p (t) && ! can_address_p (t)))
554 if (TREE_CODE (t) == PLACEHOLDER_EXPR)
555 t = find_placeholder (t, &placeholder_ptr);
557 t = TREE_OPERAND (t, 0);
562 /* If we've already determined the alias set for a decl, just return
563 it. This is necessary for C++ anonymous unions, whose component
564 variables don't look like union members (boo!). */
565 if (TREE_CODE (t) == VAR_DECL
566 && DECL_RTL_SET_P (t) && GET_CODE (DECL_RTL (t)) == MEM)
567 return MEM_ALIAS_SET (DECL_RTL (t));
569 /* Now all we care about is the type. */
573 /* Variant qualifiers don't affect the alias set, so get the main
574 variant. If this is a type with a known alias set, return it. */
575 t = TYPE_MAIN_VARIANT (t);
576 if (TYPE_ALIAS_SET_KNOWN_P (t))
577 return TYPE_ALIAS_SET (t);
579 /* See if the language has special handling for this type. */
580 set = lang_hooks.get_alias_set (t);
584 /* There are no objects of FUNCTION_TYPE, so there's no point in
585 using up an alias set for them. (There are, of course, pointers
586 and references to functions, but that's different.) */
587 else if (TREE_CODE (t) == FUNCTION_TYPE)
590 /* Unless the language specifies otherwise, let vector types alias
591 their components. This avoids some nasty type punning issues in
592 normal usage. And indeed lets vectors be treated more like an
594 else if (TREE_CODE (t) == VECTOR_TYPE)
595 set = get_alias_set (TREE_TYPE (t));
598 /* Otherwise make a new alias set for this type. */
599 set = new_alias_set ();
601 TYPE_ALIAS_SET (t) = set;
603 /* If this is an aggregate type, we must record any component aliasing
605 if (AGGREGATE_TYPE_P (t) || TREE_CODE (t) == COMPLEX_TYPE)
606 record_component_aliases (t);
611 /* Return a brand-new alias set. */
613 static GTY(()) HOST_WIDE_INT last_alias_set;
618 if (flag_strict_aliasing)
621 VARRAY_GENERIC_PTR_INIT (alias_sets, 10, "alias sets");
623 VARRAY_GROW (alias_sets, last_alias_set + 2);
624 return ++last_alias_set;
630 /* Indicate that things in SUBSET can alias things in SUPERSET, but that
631 not everything that aliases SUPERSET also aliases SUBSET. For example,
632 in C, a store to an `int' can alias a load of a structure containing an
633 `int', and vice versa. But it can't alias a load of a 'double' member
634 of the same structure. Here, the structure would be the SUPERSET and
635 `int' the SUBSET. This relationship is also described in the comment at
636 the beginning of this file.
638 This function should be called only once per SUPERSET/SUBSET pair.
640 It is illegal for SUPERSET to be zero; everything is implicitly a
641 subset of alias set zero. */
644 record_alias_subset (HOST_WIDE_INT superset, HOST_WIDE_INT subset)
646 alias_set_entry superset_entry;
647 alias_set_entry subset_entry;
649 /* It is possible in complex type situations for both sets to be the same,
650 in which case we can ignore this operation. */
651 if (superset == subset)
657 superset_entry = get_alias_set_entry (superset);
658 if (superset_entry == 0)
660 /* Create an entry for the SUPERSET, so that we have a place to
661 attach the SUBSET. */
662 superset_entry = ggc_alloc (sizeof (struct alias_set_entry));
663 superset_entry->alias_set = superset;
664 superset_entry->children
665 = splay_tree_new_ggc (splay_tree_compare_ints);
666 superset_entry->has_zero_child = 0;
667 VARRAY_GENERIC_PTR (alias_sets, superset) = superset_entry;
671 superset_entry->has_zero_child = 1;
674 subset_entry = get_alias_set_entry (subset);
675 /* If there is an entry for the subset, enter all of its children
676 (if they are not already present) as children of the SUPERSET. */
679 if (subset_entry->has_zero_child)
680 superset_entry->has_zero_child = 1;
682 splay_tree_foreach (subset_entry->children, insert_subset_children,
683 superset_entry->children);
686 /* Enter the SUBSET itself as a child of the SUPERSET. */
687 splay_tree_insert (superset_entry->children,
688 (splay_tree_key) subset, 0);
692 /* Record that component types of TYPE, if any, are part of that type for
693 aliasing purposes. For record types, we only record component types
694 for fields that are marked addressable. For array types, we always
695 record the component types, so the front end should not call this
696 function if the individual component aren't addressable. */
699 record_component_aliases (tree type)
701 HOST_WIDE_INT superset = get_alias_set (type);
707 switch (TREE_CODE (type))
710 if (! TYPE_NONALIASED_COMPONENT (type))
711 record_alias_subset (superset, get_alias_set (TREE_TYPE (type)));
716 case QUAL_UNION_TYPE:
717 /* Recursively record aliases for the base classes, if there are any. */
718 if (TYPE_BINFO (type) != NULL && TYPE_BINFO_BASETYPES (type) != NULL)
721 for (i = 0; i < TREE_VEC_LENGTH (TYPE_BINFO_BASETYPES (type)); i++)
723 tree binfo = TREE_VEC_ELT (TYPE_BINFO_BASETYPES (type), i);
724 record_alias_subset (superset,
725 get_alias_set (BINFO_TYPE (binfo)));
728 for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field))
729 if (TREE_CODE (field) == FIELD_DECL && ! DECL_NONADDRESSABLE_P (field))
730 record_alias_subset (superset, get_alias_set (TREE_TYPE (field)));
734 record_alias_subset (superset, get_alias_set (TREE_TYPE (type)));
742 /* Allocate an alias set for use in storing and reading from the varargs
745 static GTY(()) HOST_WIDE_INT varargs_set = -1;
748 get_varargs_alias_set (void)
750 if (varargs_set == -1)
751 varargs_set = new_alias_set ();
756 /* Likewise, but used for the fixed portions of the frame, e.g., register
759 static GTY(()) HOST_WIDE_INT frame_set = -1;
762 get_frame_alias_set (void)
765 frame_set = new_alias_set ();
770 /* Inside SRC, the source of a SET, find a base address. */
773 find_base_value (rtx src)
777 switch (GET_CODE (src))
785 /* At the start of a function, argument registers have known base
786 values which may be lost later. Returning an ADDRESS
787 expression here allows optimization based on argument values
788 even when the argument registers are used for other purposes. */
789 if (regno < FIRST_PSEUDO_REGISTER && copying_arguments)
790 return new_reg_base_value[regno];
792 /* If a pseudo has a known base value, return it. Do not do this
793 for non-fixed hard regs since it can result in a circular
794 dependency chain for registers which have values at function entry.
796 The test above is not sufficient because the scheduler may move
797 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
798 if ((regno >= FIRST_PSEUDO_REGISTER || fixed_regs[regno])
799 && regno < VARRAY_SIZE (reg_base_value))
801 /* If we're inside init_alias_analysis, use new_reg_base_value
802 to reduce the number of relaxation iterations. */
803 if (new_reg_base_value && new_reg_base_value[regno]
804 && REG_N_SETS (regno) == 1)
805 return new_reg_base_value[regno];
807 if (VARRAY_RTX (reg_base_value, regno))
808 return VARRAY_RTX (reg_base_value, regno);
814 /* Check for an argument passed in memory. Only record in the
815 copying-arguments block; it is too hard to track changes
817 if (copying_arguments
818 && (XEXP (src, 0) == arg_pointer_rtx
819 || (GET_CODE (XEXP (src, 0)) == PLUS
820 && XEXP (XEXP (src, 0), 0) == arg_pointer_rtx)))
821 return gen_rtx_ADDRESS (VOIDmode, src);
826 if (GET_CODE (src) != PLUS && GET_CODE (src) != MINUS)
829 /* ... fall through ... */
834 rtx temp, src_0 = XEXP (src, 0), src_1 = XEXP (src, 1);
836 /* If either operand is a REG that is a known pointer, then it
838 if (REG_P (src_0) && REG_POINTER (src_0))
839 return find_base_value (src_0);
840 if (REG_P (src_1) && REG_POINTER (src_1))
841 return find_base_value (src_1);
843 /* If either operand is a REG, then see if we already have
844 a known value for it. */
847 temp = find_base_value (src_0);
854 temp = find_base_value (src_1);
859 /* If either base is named object or a special address
860 (like an argument or stack reference), then use it for the
863 && (GET_CODE (src_0) == SYMBOL_REF
864 || GET_CODE (src_0) == LABEL_REF
865 || (GET_CODE (src_0) == ADDRESS
866 && GET_MODE (src_0) != VOIDmode)))
870 && (GET_CODE (src_1) == SYMBOL_REF
871 || GET_CODE (src_1) == LABEL_REF
872 || (GET_CODE (src_1) == ADDRESS
873 && GET_MODE (src_1) != VOIDmode)))
876 /* Guess which operand is the base address:
877 If either operand is a symbol, then it is the base. If
878 either operand is a CONST_INT, then the other is the base. */
879 if (GET_CODE (src_1) == CONST_INT || CONSTANT_P (src_0))
880 return find_base_value (src_0);
881 else if (GET_CODE (src_0) == CONST_INT || CONSTANT_P (src_1))
882 return find_base_value (src_1);
888 /* The standard form is (lo_sum reg sym) so look only at the
890 return find_base_value (XEXP (src, 1));
893 /* If the second operand is constant set the base
894 address to the first operand. */
895 if (GET_CODE (XEXP (src, 1)) == CONST_INT && INTVAL (XEXP (src, 1)) != 0)
896 return find_base_value (XEXP (src, 0));
900 if (GET_MODE_SIZE (GET_MODE (src)) < GET_MODE_SIZE (Pmode))
910 return find_base_value (XEXP (src, 0));
913 case SIGN_EXTEND: /* used for NT/Alpha pointers */
915 rtx temp = find_base_value (XEXP (src, 0));
917 if (temp != 0 && CONSTANT_P (temp))
918 temp = convert_memory_address (Pmode, temp);
930 /* Called from init_alias_analysis indirectly through note_stores. */
932 /* While scanning insns to find base values, reg_seen[N] is nonzero if
933 register N has been set in this function. */
934 static char *reg_seen;
936 /* Addresses which are known not to alias anything else are identified
937 by a unique integer. */
938 static int unique_id;
941 record_set (rtx dest, rtx set, void *data ATTRIBUTE_UNUSED)
947 if (GET_CODE (dest) != REG)
950 regno = REGNO (dest);
952 if (regno >= VARRAY_SIZE (reg_base_value))
955 /* If this spans multiple hard registers, then we must indicate that every
956 register has an unusable value. */
957 if (regno < FIRST_PSEUDO_REGISTER)
958 n = hard_regno_nregs[regno][GET_MODE (dest)];
965 reg_seen[regno + n] = 1;
966 new_reg_base_value[regno + n] = 0;
973 /* A CLOBBER wipes out any old value but does not prevent a previously
974 unset register from acquiring a base address (i.e. reg_seen is not
976 if (GET_CODE (set) == CLOBBER)
978 new_reg_base_value[regno] = 0;
987 new_reg_base_value[regno] = 0;
991 new_reg_base_value[regno] = gen_rtx_ADDRESS (Pmode,
992 GEN_INT (unique_id++));
996 /* If this is not the first set of REGNO, see whether the new value
997 is related to the old one. There are two cases of interest:
999 (1) The register might be assigned an entirely new value
1000 that has the same base term as the original set.
1002 (2) The set might be a simple self-modification that
1003 cannot change REGNO's base value.
1005 If neither case holds, reject the original base value as invalid.
1006 Note that the following situation is not detected:
1008 extern int x, y; int *p = &x; p += (&y-&x);
1010 ANSI C does not allow computing the difference of addresses
1011 of distinct top level objects. */
1012 if (new_reg_base_value[regno] != 0
1013 && find_base_value (src) != new_reg_base_value[regno])
1014 switch (GET_CODE (src))
1018 if (XEXP (src, 0) != dest && XEXP (src, 1) != dest)
1019 new_reg_base_value[regno] = 0;
1022 /* If the value we add in the PLUS is also a valid base value,
1023 this might be the actual base value, and the original value
1026 rtx other = NULL_RTX;
1028 if (XEXP (src, 0) == dest)
1029 other = XEXP (src, 1);
1030 else if (XEXP (src, 1) == dest)
1031 other = XEXP (src, 0);
1033 if (! other || find_base_value (other))
1034 new_reg_base_value[regno] = 0;
1038 if (XEXP (src, 0) != dest || GET_CODE (XEXP (src, 1)) != CONST_INT)
1039 new_reg_base_value[regno] = 0;
1042 new_reg_base_value[regno] = 0;
1045 /* If this is the first set of a register, record the value. */
1046 else if ((regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
1047 && ! reg_seen[regno] && new_reg_base_value[regno] == 0)
1048 new_reg_base_value[regno] = find_base_value (src);
1050 reg_seen[regno] = 1;
1053 /* Called from loop optimization when a new pseudo-register is
1054 created. It indicates that REGNO is being set to VAL. f INVARIANT
1055 is true then this value also describes an invariant relationship
1056 which can be used to deduce that two registers with unknown values
1060 record_base_value (unsigned int regno, rtx val, int invariant)
1062 if (invariant && alias_invariant && regno < alias_invariant_size)
1063 alias_invariant[regno] = val;
1065 if (regno >= VARRAY_SIZE (reg_base_value))
1066 VARRAY_GROW (reg_base_value, max_reg_num ());
1068 if (GET_CODE (val) == REG)
1070 VARRAY_RTX (reg_base_value, regno)
1071 = REG_BASE_VALUE (val);
1074 VARRAY_RTX (reg_base_value, regno)
1075 = find_base_value (val);
1078 /* Clear alias info for a register. This is used if an RTL transformation
1079 changes the value of a register. This is used in flow by AUTO_INC_DEC
1080 optimizations. We don't need to clear reg_base_value, since flow only
1081 changes the offset. */
1084 clear_reg_alias_info (rtx reg)
1086 unsigned int regno = REGNO (reg);
1088 if (regno < reg_known_value_size && regno >= FIRST_PSEUDO_REGISTER)
1089 reg_known_value[regno] = reg;
1092 /* Returns a canonical version of X, from the point of view alias
1093 analysis. (For example, if X is a MEM whose address is a register,
1094 and the register has a known value (say a SYMBOL_REF), then a MEM
1095 whose address is the SYMBOL_REF is returned.) */
1100 /* Recursively look for equivalences. */
1101 if (GET_CODE (x) == REG && REGNO (x) >= FIRST_PSEUDO_REGISTER
1102 && REGNO (x) < reg_known_value_size)
1103 return reg_known_value[REGNO (x)] == x
1104 ? x : canon_rtx (reg_known_value[REGNO (x)]);
1105 else if (GET_CODE (x) == PLUS)
1107 rtx x0 = canon_rtx (XEXP (x, 0));
1108 rtx x1 = canon_rtx (XEXP (x, 1));
1110 if (x0 != XEXP (x, 0) || x1 != XEXP (x, 1))
1112 if (GET_CODE (x0) == CONST_INT)
1113 return plus_constant (x1, INTVAL (x0));
1114 else if (GET_CODE (x1) == CONST_INT)
1115 return plus_constant (x0, INTVAL (x1));
1116 return gen_rtx_PLUS (GET_MODE (x), x0, x1);
1120 /* This gives us much better alias analysis when called from
1121 the loop optimizer. Note we want to leave the original
1122 MEM alone, but need to return the canonicalized MEM with
1123 all the flags with their original values. */
1124 else if (GET_CODE (x) == MEM)
1125 x = replace_equiv_address_nv (x, canon_rtx (XEXP (x, 0)));
1130 /* Return 1 if X and Y are identical-looking rtx's.
1131 Expect that X and Y has been already canonicalized.
1133 We use the data in reg_known_value above to see if two registers with
1134 different numbers are, in fact, equivalent. */
1137 rtx_equal_for_memref_p (rtx x, rtx y)
1144 if (x == 0 && y == 0)
1146 if (x == 0 || y == 0)
1152 code = GET_CODE (x);
1153 /* Rtx's of different codes cannot be equal. */
1154 if (code != GET_CODE (y))
1157 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1158 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1160 if (GET_MODE (x) != GET_MODE (y))
1163 /* Some RTL can be compared without a recursive examination. */
1167 return REGNO (x) == REGNO (y);
1170 return XEXP (x, 0) == XEXP (y, 0);
1173 return XSTR (x, 0) == XSTR (y, 0);
1178 /* There's no need to compare the contents of CONST_DOUBLEs or
1179 CONST_INTs because pointer equality is a good enough
1180 comparison for these nodes. */
1184 return (XINT (x, 1) == XINT (y, 1)
1185 && rtx_equal_for_memref_p (XEXP (x, 0),
1192 /* canon_rtx knows how to handle plus. No need to canonicalize. */
1194 return ((rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0))
1195 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1)))
1196 || (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 1))
1197 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 0))));
1198 /* For commutative operations, the RTX match if the operand match in any
1199 order. Also handle the simple binary and unary cases without a loop. */
1200 if (COMMUTATIVE_P (x))
1202 rtx xop0 = canon_rtx (XEXP (x, 0));
1203 rtx yop0 = canon_rtx (XEXP (y, 0));
1204 rtx yop1 = canon_rtx (XEXP (y, 1));
1206 return ((rtx_equal_for_memref_p (xop0, yop0)
1207 && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)), yop1))
1208 || (rtx_equal_for_memref_p (xop0, yop1)
1209 && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)), yop0)));
1211 else if (NON_COMMUTATIVE_P (x))
1213 return (rtx_equal_for_memref_p (canon_rtx (XEXP (x, 0)),
1214 canon_rtx (XEXP (y, 0)))
1215 && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)),
1216 canon_rtx (XEXP (y, 1))));
1218 else if (UNARY_P (x))
1219 return rtx_equal_for_memref_p (canon_rtx (XEXP (x, 0)),
1220 canon_rtx (XEXP (y, 0)));
1222 /* Compare the elements. If any pair of corresponding elements
1223 fail to match, return 0 for the whole things.
1225 Limit cases to types which actually appear in addresses. */
1227 fmt = GET_RTX_FORMAT (code);
1228 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1233 if (XINT (x, i) != XINT (y, i))
1238 /* Two vectors must have the same length. */
1239 if (XVECLEN (x, i) != XVECLEN (y, i))
1242 /* And the corresponding elements must match. */
1243 for (j = 0; j < XVECLEN (x, i); j++)
1244 if (rtx_equal_for_memref_p (canon_rtx (XVECEXP (x, i, j)),
1245 canon_rtx (XVECEXP (y, i, j))) == 0)
1250 if (rtx_equal_for_memref_p (canon_rtx (XEXP (x, i)),
1251 canon_rtx (XEXP (y, i))) == 0)
1255 /* This can happen for asm operands. */
1257 if (strcmp (XSTR (x, i), XSTR (y, i)))
1261 /* This can happen for an asm which clobbers memory. */
1265 /* It is believed that rtx's at this level will never
1266 contain anything but integers and other rtx's,
1267 except for within LABEL_REFs and SYMBOL_REFs. */
1275 /* Given an rtx X, find a SYMBOL_REF or LABEL_REF within
1276 X and return it, or return 0 if none found. */
1279 find_symbolic_term (rtx x)
1285 code = GET_CODE (x);
1286 if (code == SYMBOL_REF || code == LABEL_REF)
1291 fmt = GET_RTX_FORMAT (code);
1292 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1298 t = find_symbolic_term (XEXP (x, i));
1302 else if (fmt[i] == 'E')
1309 find_base_term (rtx x)
1312 struct elt_loc_list *l;
1314 #if defined (FIND_BASE_TERM)
1315 /* Try machine-dependent ways to find the base term. */
1316 x = FIND_BASE_TERM (x);
1319 switch (GET_CODE (x))
1322 return REG_BASE_VALUE (x);
1325 if (GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (Pmode))
1335 return find_base_term (XEXP (x, 0));
1338 case SIGN_EXTEND: /* Used for Alpha/NT pointers */
1340 rtx temp = find_base_term (XEXP (x, 0));
1342 if (temp != 0 && CONSTANT_P (temp))
1343 temp = convert_memory_address (Pmode, temp);
1349 val = CSELIB_VAL_PTR (x);
1352 for (l = val->locs; l; l = l->next)
1353 if ((x = find_base_term (l->loc)) != 0)
1359 if (GET_CODE (x) != PLUS && GET_CODE (x) != MINUS)
1366 rtx tmp1 = XEXP (x, 0);
1367 rtx tmp2 = XEXP (x, 1);
1369 /* This is a little bit tricky since we have to determine which of
1370 the two operands represents the real base address. Otherwise this
1371 routine may return the index register instead of the base register.
1373 That may cause us to believe no aliasing was possible, when in
1374 fact aliasing is possible.
1376 We use a few simple tests to guess the base register. Additional
1377 tests can certainly be added. For example, if one of the operands
1378 is a shift or multiply, then it must be the index register and the
1379 other operand is the base register. */
1381 if (tmp1 == pic_offset_table_rtx && CONSTANT_P (tmp2))
1382 return find_base_term (tmp2);
1384 /* If either operand is known to be a pointer, then use it
1385 to determine the base term. */
1386 if (REG_P (tmp1) && REG_POINTER (tmp1))
1387 return find_base_term (tmp1);
1389 if (REG_P (tmp2) && REG_POINTER (tmp2))
1390 return find_base_term (tmp2);
1392 /* Neither operand was known to be a pointer. Go ahead and find the
1393 base term for both operands. */
1394 tmp1 = find_base_term (tmp1);
1395 tmp2 = find_base_term (tmp2);
1397 /* If either base term is named object or a special address
1398 (like an argument or stack reference), then use it for the
1401 && (GET_CODE (tmp1) == SYMBOL_REF
1402 || GET_CODE (tmp1) == LABEL_REF
1403 || (GET_CODE (tmp1) == ADDRESS
1404 && GET_MODE (tmp1) != VOIDmode)))
1408 && (GET_CODE (tmp2) == SYMBOL_REF
1409 || GET_CODE (tmp2) == LABEL_REF
1410 || (GET_CODE (tmp2) == ADDRESS
1411 && GET_MODE (tmp2) != VOIDmode)))
1414 /* We could not determine which of the two operands was the
1415 base register and which was the index. So we can determine
1416 nothing from the base alias check. */
1421 if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) != 0)
1422 return find_base_term (XEXP (x, 0));
1430 return REG_BASE_VALUE (frame_pointer_rtx);
1437 /* Return 0 if the addresses X and Y are known to point to different
1438 objects, 1 if they might be pointers to the same object. */
1441 base_alias_check (rtx x, rtx y, enum machine_mode x_mode,
1442 enum machine_mode y_mode)
1444 rtx x_base = find_base_term (x);
1445 rtx y_base = find_base_term (y);
1447 /* If the address itself has no known base see if a known equivalent
1448 value has one. If either address still has no known base, nothing
1449 is known about aliasing. */
1454 if (! flag_expensive_optimizations || (x_c = canon_rtx (x)) == x)
1457 x_base = find_base_term (x_c);
1465 if (! flag_expensive_optimizations || (y_c = canon_rtx (y)) == y)
1468 y_base = find_base_term (y_c);
1473 /* If the base addresses are equal nothing is known about aliasing. */
1474 if (rtx_equal_p (x_base, y_base))
1477 /* The base addresses of the read and write are different expressions.
1478 If they are both symbols and they are not accessed via AND, there is
1479 no conflict. We can bring knowledge of object alignment into play
1480 here. For example, on alpha, "char a, b;" can alias one another,
1481 though "char a; long b;" cannot. */
1482 if (GET_CODE (x_base) != ADDRESS && GET_CODE (y_base) != ADDRESS)
1484 if (GET_CODE (x) == AND && GET_CODE (y) == AND)
1486 if (GET_CODE (x) == AND
1487 && (GET_CODE (XEXP (x, 1)) != CONST_INT
1488 || (int) GET_MODE_UNIT_SIZE (y_mode) < -INTVAL (XEXP (x, 1))))
1490 if (GET_CODE (y) == AND
1491 && (GET_CODE (XEXP (y, 1)) != CONST_INT
1492 || (int) GET_MODE_UNIT_SIZE (x_mode) < -INTVAL (XEXP (y, 1))))
1494 /* Differing symbols never alias. */
1498 /* If one address is a stack reference there can be no alias:
1499 stack references using different base registers do not alias,
1500 a stack reference can not alias a parameter, and a stack reference
1501 can not alias a global. */
1502 if ((GET_CODE (x_base) == ADDRESS && GET_MODE (x_base) == Pmode)
1503 || (GET_CODE (y_base) == ADDRESS && GET_MODE (y_base) == Pmode))
1506 if (! flag_argument_noalias)
1509 if (flag_argument_noalias > 1)
1512 /* Weak noalias assertion (arguments are distinct, but may match globals). */
1513 return ! (GET_MODE (x_base) == VOIDmode && GET_MODE (y_base) == VOIDmode);
1516 /* Convert the address X into something we can use. This is done by returning
1517 it unchanged unless it is a value; in the latter case we call cselib to get
1518 a more useful rtx. */
1524 struct elt_loc_list *l;
1526 if (GET_CODE (x) != VALUE)
1528 v = CSELIB_VAL_PTR (x);
1531 for (l = v->locs; l; l = l->next)
1532 if (CONSTANT_P (l->loc))
1534 for (l = v->locs; l; l = l->next)
1535 if (GET_CODE (l->loc) != REG && GET_CODE (l->loc) != MEM)
1538 return v->locs->loc;
1543 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
1544 where SIZE is the size in bytes of the memory reference. If ADDR
1545 is not modified by the memory reference then ADDR is returned. */
1548 addr_side_effect_eval (rtx addr, int size, int n_refs)
1552 switch (GET_CODE (addr))
1555 offset = (n_refs + 1) * size;
1558 offset = -(n_refs + 1) * size;
1561 offset = n_refs * size;
1564 offset = -n_refs * size;
1572 addr = gen_rtx_PLUS (GET_MODE (addr), XEXP (addr, 0),
1575 addr = XEXP (addr, 0);
1576 addr = canon_rtx (addr);
1581 /* Return nonzero if X and Y (memory addresses) could reference the
1582 same location in memory. C is an offset accumulator. When
1583 C is nonzero, we are testing aliases between X and Y + C.
1584 XSIZE is the size in bytes of the X reference,
1585 similarly YSIZE is the size in bytes for Y.
1586 Expect that canon_rtx has been already called for X and Y.
1588 If XSIZE or YSIZE is zero, we do not know the amount of memory being
1589 referenced (the reference was BLKmode), so make the most pessimistic
1592 If XSIZE or YSIZE is negative, we may access memory outside the object
1593 being referenced as a side effect. This can happen when using AND to
1594 align memory references, as is done on the Alpha.
1596 Nice to notice that varying addresses cannot conflict with fp if no
1597 local variables had their addresses taken, but that's too hard now. */
1600 memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c)
1602 if (GET_CODE (x) == VALUE)
1604 if (GET_CODE (y) == VALUE)
1606 if (GET_CODE (x) == HIGH)
1608 else if (GET_CODE (x) == LO_SUM)
1611 x = addr_side_effect_eval (x, xsize, 0);
1612 if (GET_CODE (y) == HIGH)
1614 else if (GET_CODE (y) == LO_SUM)
1617 y = addr_side_effect_eval (y, ysize, 0);
1619 if (rtx_equal_for_memref_p (x, y))
1621 if (xsize <= 0 || ysize <= 0)
1623 if (c >= 0 && xsize > c)
1625 if (c < 0 && ysize+c > 0)
1630 /* This code used to check for conflicts involving stack references and
1631 globals but the base address alias code now handles these cases. */
1633 if (GET_CODE (x) == PLUS)
1635 /* The fact that X is canonicalized means that this
1636 PLUS rtx is canonicalized. */
1637 rtx x0 = XEXP (x, 0);
1638 rtx x1 = XEXP (x, 1);
1640 if (GET_CODE (y) == PLUS)
1642 /* The fact that Y is canonicalized means that this
1643 PLUS rtx is canonicalized. */
1644 rtx y0 = XEXP (y, 0);
1645 rtx y1 = XEXP (y, 1);
1647 if (rtx_equal_for_memref_p (x1, y1))
1648 return memrefs_conflict_p (xsize, x0, ysize, y0, c);
1649 if (rtx_equal_for_memref_p (x0, y0))
1650 return memrefs_conflict_p (xsize, x1, ysize, y1, c);
1651 if (GET_CODE (x1) == CONST_INT)
1653 if (GET_CODE (y1) == CONST_INT)
1654 return memrefs_conflict_p (xsize, x0, ysize, y0,
1655 c - INTVAL (x1) + INTVAL (y1));
1657 return memrefs_conflict_p (xsize, x0, ysize, y,
1660 else if (GET_CODE (y1) == CONST_INT)
1661 return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
1665 else if (GET_CODE (x1) == CONST_INT)
1666 return memrefs_conflict_p (xsize, x0, ysize, y, c - INTVAL (x1));
1668 else if (GET_CODE (y) == PLUS)
1670 /* The fact that Y is canonicalized means that this
1671 PLUS rtx is canonicalized. */
1672 rtx y0 = XEXP (y, 0);
1673 rtx y1 = XEXP (y, 1);
1675 if (GET_CODE (y1) == CONST_INT)
1676 return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
1681 if (GET_CODE (x) == GET_CODE (y))
1682 switch (GET_CODE (x))
1686 /* Handle cases where we expect the second operands to be the
1687 same, and check only whether the first operand would conflict
1690 rtx x1 = canon_rtx (XEXP (x, 1));
1691 rtx y1 = canon_rtx (XEXP (y, 1));
1692 if (! rtx_equal_for_memref_p (x1, y1))
1694 x0 = canon_rtx (XEXP (x, 0));
1695 y0 = canon_rtx (XEXP (y, 0));
1696 if (rtx_equal_for_memref_p (x0, y0))
1697 return (xsize == 0 || ysize == 0
1698 || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
1700 /* Can't properly adjust our sizes. */
1701 if (GET_CODE (x1) != CONST_INT)
1703 xsize /= INTVAL (x1);
1704 ysize /= INTVAL (x1);
1706 return memrefs_conflict_p (xsize, x0, ysize, y0, c);
1710 /* Are these registers known not to be equal? */
1711 if (alias_invariant)
1713 unsigned int r_x = REGNO (x), r_y = REGNO (y);
1714 rtx i_x, i_y; /* invariant relationships of X and Y */
1716 i_x = r_x >= alias_invariant_size ? 0 : alias_invariant[r_x];
1717 i_y = r_y >= alias_invariant_size ? 0 : alias_invariant[r_y];
1719 if (i_x == 0 && i_y == 0)
1722 if (! memrefs_conflict_p (xsize, i_x ? i_x : x,
1723 ysize, i_y ? i_y : y, c))
1732 /* Treat an access through an AND (e.g. a subword access on an Alpha)
1733 as an access with indeterminate size. Assume that references
1734 besides AND are aligned, so if the size of the other reference is
1735 at least as large as the alignment, assume no other overlap. */
1736 if (GET_CODE (x) == AND && GET_CODE (XEXP (x, 1)) == CONST_INT)
1738 if (GET_CODE (y) == AND || ysize < -INTVAL (XEXP (x, 1)))
1740 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)), ysize, y, c);
1742 if (GET_CODE (y) == AND && GET_CODE (XEXP (y, 1)) == CONST_INT)
1744 /* ??? If we are indexing far enough into the array/structure, we
1745 may yet be able to determine that we can not overlap. But we
1746 also need to that we are far enough from the end not to overlap
1747 a following reference, so we do nothing with that for now. */
1748 if (GET_CODE (x) == AND || xsize < -INTVAL (XEXP (y, 1)))
1750 return memrefs_conflict_p (xsize, x, ysize, canon_rtx (XEXP (y, 0)), c);
1753 if (GET_CODE (x) == ADDRESSOF)
1755 if (y == frame_pointer_rtx
1756 || GET_CODE (y) == ADDRESSOF)
1757 return xsize <= 0 || ysize <= 0;
1759 if (GET_CODE (y) == ADDRESSOF)
1761 if (x == frame_pointer_rtx)
1762 return xsize <= 0 || ysize <= 0;
1767 if (GET_CODE (x) == CONST_INT && GET_CODE (y) == CONST_INT)
1769 c += (INTVAL (y) - INTVAL (x));
1770 return (xsize <= 0 || ysize <= 0
1771 || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
1774 if (GET_CODE (x) == CONST)
1776 if (GET_CODE (y) == CONST)
1777 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
1778 ysize, canon_rtx (XEXP (y, 0)), c);
1780 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
1783 if (GET_CODE (y) == CONST)
1784 return memrefs_conflict_p (xsize, x, ysize,
1785 canon_rtx (XEXP (y, 0)), c);
1788 return (xsize <= 0 || ysize <= 0
1789 || (rtx_equal_for_memref_p (x, y)
1790 && ((c >= 0 && xsize > c) || (c < 0 && ysize+c > 0))));
1797 /* Functions to compute memory dependencies.
1799 Since we process the insns in execution order, we can build tables
1800 to keep track of what registers are fixed (and not aliased), what registers
1801 are varying in known ways, and what registers are varying in unknown
1804 If both memory references are volatile, then there must always be a
1805 dependence between the two references, since their order can not be
1806 changed. A volatile and non-volatile reference can be interchanged
1809 A MEM_IN_STRUCT reference at a non-AND varying address can never
1810 conflict with a non-MEM_IN_STRUCT reference at a fixed address. We
1811 also must allow AND addresses, because they may generate accesses
1812 outside the object being referenced. This is used to generate
1813 aligned addresses from unaligned addresses, for instance, the alpha
1814 storeqi_unaligned pattern. */
1816 /* Read dependence: X is read after read in MEM takes place. There can
1817 only be a dependence here if both reads are volatile. */
1820 read_dependence (rtx mem, rtx x)
1822 return MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem);
1825 /* Returns MEM1 if and only if MEM1 is a scalar at a fixed address and
1826 MEM2 is a reference to a structure at a varying address, or returns
1827 MEM2 if vice versa. Otherwise, returns NULL_RTX. If a non-NULL
1828 value is returned MEM1 and MEM2 can never alias. VARIES_P is used
1829 to decide whether or not an address may vary; it should return
1830 nonzero whenever variation is possible.
1831 MEM1_ADDR and MEM2_ADDR are the addresses of MEM1 and MEM2. */
1834 fixed_scalar_and_varying_struct_p (rtx mem1, rtx mem2, rtx mem1_addr,
1836 int (*varies_p) (rtx, int))
1838 if (! flag_strict_aliasing)
1841 if (MEM_SCALAR_P (mem1) && MEM_IN_STRUCT_P (mem2)
1842 && !varies_p (mem1_addr, 1) && varies_p (mem2_addr, 1))
1843 /* MEM1 is a scalar at a fixed address; MEM2 is a struct at a
1847 if (MEM_IN_STRUCT_P (mem1) && MEM_SCALAR_P (mem2)
1848 && varies_p (mem1_addr, 1) && !varies_p (mem2_addr, 1))
1849 /* MEM2 is a scalar at a fixed address; MEM1 is a struct at a
1856 /* Returns nonzero if something about the mode or address format MEM1
1857 indicates that it might well alias *anything*. */
1860 aliases_everything_p (rtx mem)
1862 if (GET_CODE (XEXP (mem, 0)) == AND)
1863 /* If the address is an AND, its very hard to know at what it is
1864 actually pointing. */
1870 /* Return true if we can determine that the fields referenced cannot
1871 overlap for any pair of objects. */
1874 nonoverlapping_component_refs_p (tree x, tree y)
1876 tree fieldx, fieldy, typex, typey, orig_y;
1880 /* The comparison has to be done at a common type, since we don't
1881 know how the inheritance hierarchy works. */
1885 fieldx = TREE_OPERAND (x, 1);
1886 typex = DECL_FIELD_CONTEXT (fieldx);
1891 fieldy = TREE_OPERAND (y, 1);
1892 typey = DECL_FIELD_CONTEXT (fieldy);
1897 y = TREE_OPERAND (y, 0);
1899 while (y && TREE_CODE (y) == COMPONENT_REF);
1901 x = TREE_OPERAND (x, 0);
1903 while (x && TREE_CODE (x) == COMPONENT_REF);
1905 /* Never found a common type. */
1909 /* If we're left with accessing different fields of a structure,
1911 if (TREE_CODE (typex) == RECORD_TYPE
1912 && fieldx != fieldy)
1915 /* The comparison on the current field failed. If we're accessing
1916 a very nested structure, look at the next outer level. */
1917 x = TREE_OPERAND (x, 0);
1918 y = TREE_OPERAND (y, 0);
1921 && TREE_CODE (x) == COMPONENT_REF
1922 && TREE_CODE (y) == COMPONENT_REF);
1927 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
1930 decl_for_component_ref (tree x)
1934 x = TREE_OPERAND (x, 0);
1936 while (x && TREE_CODE (x) == COMPONENT_REF);
1938 return x && DECL_P (x) ? x : NULL_TREE;
1941 /* Walk up the COMPONENT_REF list and adjust OFFSET to compensate for the
1942 offset of the field reference. */
1945 adjust_offset_for_component_ref (tree x, rtx offset)
1947 HOST_WIDE_INT ioffset;
1952 ioffset = INTVAL (offset);
1955 tree field = TREE_OPERAND (x, 1);
1957 if (! host_integerp (DECL_FIELD_OFFSET (field), 1))
1959 ioffset += (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1960 + (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1963 x = TREE_OPERAND (x, 0);
1965 while (x && TREE_CODE (x) == COMPONENT_REF);
1967 return GEN_INT (ioffset);
1970 /* Return nonzero if we can determine the exprs corresponding to memrefs
1971 X and Y and they do not overlap. */
1974 nonoverlapping_memrefs_p (rtx x, rtx y)
1976 tree exprx = MEM_EXPR (x), expry = MEM_EXPR (y);
1979 rtx moffsetx, moffsety;
1980 HOST_WIDE_INT offsetx = 0, offsety = 0, sizex, sizey, tem;
1982 /* Unless both have exprs, we can't tell anything. */
1983 if (exprx == 0 || expry == 0)
1986 /* If both are field references, we may be able to determine something. */
1987 if (TREE_CODE (exprx) == COMPONENT_REF
1988 && TREE_CODE (expry) == COMPONENT_REF
1989 && nonoverlapping_component_refs_p (exprx, expry))
1992 /* If the field reference test failed, look at the DECLs involved. */
1993 moffsetx = MEM_OFFSET (x);
1994 if (TREE_CODE (exprx) == COMPONENT_REF)
1996 tree t = decl_for_component_ref (exprx);
1999 moffsetx = adjust_offset_for_component_ref (exprx, moffsetx);
2002 else if (TREE_CODE (exprx) == INDIRECT_REF)
2004 exprx = TREE_OPERAND (exprx, 0);
2005 if (flag_argument_noalias < 2
2006 || TREE_CODE (exprx) != PARM_DECL)
2010 moffsety = MEM_OFFSET (y);
2011 if (TREE_CODE (expry) == COMPONENT_REF)
2013 tree t = decl_for_component_ref (expry);
2016 moffsety = adjust_offset_for_component_ref (expry, moffsety);
2019 else if (TREE_CODE (expry) == INDIRECT_REF)
2021 expry = TREE_OPERAND (expry, 0);
2022 if (flag_argument_noalias < 2
2023 || TREE_CODE (expry) != PARM_DECL)
2027 if (! DECL_P (exprx) || ! DECL_P (expry))
2030 rtlx = DECL_RTL (exprx);
2031 rtly = DECL_RTL (expry);
2033 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
2034 can't overlap unless they are the same because we never reuse that part
2035 of the stack frame used for locals for spilled pseudos. */
2036 if ((GET_CODE (rtlx) != MEM || GET_CODE (rtly) != MEM)
2037 && ! rtx_equal_p (rtlx, rtly))
2040 /* Get the base and offsets of both decls. If either is a register, we
2041 know both are and are the same, so use that as the base. The only
2042 we can avoid overlap is if we can deduce that they are nonoverlapping
2043 pieces of that decl, which is very rare. */
2044 basex = GET_CODE (rtlx) == MEM ? XEXP (rtlx, 0) : rtlx;
2045 if (GET_CODE (basex) == PLUS && GET_CODE (XEXP (basex, 1)) == CONST_INT)
2046 offsetx = INTVAL (XEXP (basex, 1)), basex = XEXP (basex, 0);
2048 basey = GET_CODE (rtly) == MEM ? XEXP (rtly, 0) : rtly;
2049 if (GET_CODE (basey) == PLUS && GET_CODE (XEXP (basey, 1)) == CONST_INT)
2050 offsety = INTVAL (XEXP (basey, 1)), basey = XEXP (basey, 0);
2052 /* If the bases are different, we know they do not overlap if both
2053 are constants or if one is a constant and the other a pointer into the
2054 stack frame. Otherwise a different base means we can't tell if they
2056 if (! rtx_equal_p (basex, basey))
2057 return ((CONSTANT_P (basex) && CONSTANT_P (basey))
2058 || (CONSTANT_P (basex) && REG_P (basey)
2059 && REGNO_PTR_FRAME_P (REGNO (basey)))
2060 || (CONSTANT_P (basey) && REG_P (basex)
2061 && REGNO_PTR_FRAME_P (REGNO (basex))));
2063 sizex = (GET_CODE (rtlx) != MEM ? (int) GET_MODE_SIZE (GET_MODE (rtlx))
2064 : MEM_SIZE (rtlx) ? INTVAL (MEM_SIZE (rtlx))
2066 sizey = (GET_CODE (rtly) != MEM ? (int) GET_MODE_SIZE (GET_MODE (rtly))
2067 : MEM_SIZE (rtly) ? INTVAL (MEM_SIZE (rtly)) :
2070 /* If we have an offset for either memref, it can update the values computed
2073 offsetx += INTVAL (moffsetx), sizex -= INTVAL (moffsetx);
2075 offsety += INTVAL (moffsety), sizey -= INTVAL (moffsety);
2077 /* If a memref has both a size and an offset, we can use the smaller size.
2078 We can't do this if the offset isn't known because we must view this
2079 memref as being anywhere inside the DECL's MEM. */
2080 if (MEM_SIZE (x) && moffsetx)
2081 sizex = INTVAL (MEM_SIZE (x));
2082 if (MEM_SIZE (y) && moffsety)
2083 sizey = INTVAL (MEM_SIZE (y));
2085 /* Put the values of the memref with the lower offset in X's values. */
2086 if (offsetx > offsety)
2088 tem = offsetx, offsetx = offsety, offsety = tem;
2089 tem = sizex, sizex = sizey, sizey = tem;
2092 /* If we don't know the size of the lower-offset value, we can't tell
2093 if they conflict. Otherwise, we do the test. */
2094 return sizex >= 0 && offsety >= offsetx + sizex;
2097 /* True dependence: X is read after store in MEM takes place. */
2100 true_dependence (rtx mem, enum machine_mode mem_mode, rtx x,
2101 int (*varies) (rtx, int))
2103 rtx x_addr, mem_addr;
2106 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2109 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2110 This is used in epilogue deallocation functions. */
2111 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
2113 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
2116 if (DIFFERENT_ALIAS_SETS_P (x, mem))
2119 /* Unchanging memory can't conflict with non-unchanging memory.
2120 A non-unchanging read can conflict with a non-unchanging write.
2121 An unchanging read can conflict with an unchanging write since
2122 there may be a single store to this address to initialize it.
2123 Note that an unchanging store can conflict with a non-unchanging read
2124 since we have to make conservative assumptions when we have a
2125 record with readonly fields and we are copying the whole thing.
2126 Just fall through to the code below to resolve potential conflicts.
2127 This won't handle all cases optimally, but the possible performance
2128 loss should be negligible. */
2129 if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem))
2132 if (nonoverlapping_memrefs_p (mem, x))
2135 if (mem_mode == VOIDmode)
2136 mem_mode = GET_MODE (mem);
2138 x_addr = get_addr (XEXP (x, 0));
2139 mem_addr = get_addr (XEXP (mem, 0));
2141 base = find_base_term (x_addr);
2142 if (base && (GET_CODE (base) == LABEL_REF
2143 || (GET_CODE (base) == SYMBOL_REF
2144 && CONSTANT_POOL_ADDRESS_P (base))))
2147 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode))
2150 x_addr = canon_rtx (x_addr);
2151 mem_addr = canon_rtx (mem_addr);
2153 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
2154 SIZE_FOR_MODE (x), x_addr, 0))
2157 if (aliases_everything_p (x))
2160 /* We cannot use aliases_everything_p to test MEM, since we must look
2161 at MEM_MODE, rather than GET_MODE (MEM). */
2162 if (mem_mode == QImode || GET_CODE (mem_addr) == AND)
2165 /* In true_dependence we also allow BLKmode to alias anything. Why
2166 don't we do this in anti_dependence and output_dependence? */
2167 if (mem_mode == BLKmode || GET_MODE (x) == BLKmode)
2170 return ! fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr,
2174 /* Canonical true dependence: X is read after store in MEM takes place.
2175 Variant of true_dependence which assumes MEM has already been
2176 canonicalized (hence we no longer do that here).
2177 The mem_addr argument has been added, since true_dependence computed
2178 this value prior to canonicalizing. */
2181 canon_true_dependence (rtx mem, enum machine_mode mem_mode, rtx mem_addr,
2182 rtx x, int (*varies) (rtx, int))
2186 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2189 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2190 This is used in epilogue deallocation functions. */
2191 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
2193 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
2196 if (DIFFERENT_ALIAS_SETS_P (x, mem))
2199 /* If X is an unchanging read, then it can't possibly conflict with any
2200 non-unchanging store. It may conflict with an unchanging write though,
2201 because there may be a single store to this address to initialize it.
2202 Just fall through to the code below to resolve the case where we have
2203 both an unchanging read and an unchanging write. This won't handle all
2204 cases optimally, but the possible performance loss should be
2206 if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem))
2209 if (nonoverlapping_memrefs_p (x, mem))
2212 x_addr = get_addr (XEXP (x, 0));
2214 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode))
2217 x_addr = canon_rtx (x_addr);
2218 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
2219 SIZE_FOR_MODE (x), x_addr, 0))
2222 if (aliases_everything_p (x))
2225 /* We cannot use aliases_everything_p to test MEM, since we must look
2226 at MEM_MODE, rather than GET_MODE (MEM). */
2227 if (mem_mode == QImode || GET_CODE (mem_addr) == AND)
2230 /* In true_dependence we also allow BLKmode to alias anything. Why
2231 don't we do this in anti_dependence and output_dependence? */
2232 if (mem_mode == BLKmode || GET_MODE (x) == BLKmode)
2235 return ! fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr,
2239 /* Returns nonzero if a write to X might alias a previous read from
2240 (or, if WRITEP is nonzero, a write to) MEM. If CONSTP is nonzero,
2241 honor the RTX_UNCHANGING_P flags on X and MEM. */
2244 write_dependence_p (rtx mem, rtx x, int writep, int constp)
2246 rtx x_addr, mem_addr;
2250 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2253 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2254 This is used in epilogue deallocation functions. */
2255 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
2257 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
2260 if (DIFFERENT_ALIAS_SETS_P (x, mem))
2265 /* Unchanging memory can't conflict with non-unchanging memory. */
2266 if (RTX_UNCHANGING_P (x) != RTX_UNCHANGING_P (mem))
2269 /* If MEM is an unchanging read, then it can't possibly conflict with
2270 the store to X, because there is at most one store to MEM, and it
2271 must have occurred somewhere before MEM. */
2272 if (! writep && RTX_UNCHANGING_P (mem))
2276 if (nonoverlapping_memrefs_p (x, mem))
2279 x_addr = get_addr (XEXP (x, 0));
2280 mem_addr = get_addr (XEXP (mem, 0));
2284 base = find_base_term (mem_addr);
2285 if (base && (GET_CODE (base) == LABEL_REF
2286 || (GET_CODE (base) == SYMBOL_REF
2287 && CONSTANT_POOL_ADDRESS_P (base))))
2291 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x),
2295 x_addr = canon_rtx (x_addr);
2296 mem_addr = canon_rtx (mem_addr);
2298 if (!memrefs_conflict_p (SIZE_FOR_MODE (mem), mem_addr,
2299 SIZE_FOR_MODE (x), x_addr, 0))
2303 = fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr,
2306 return (!(fixed_scalar == mem && !aliases_everything_p (x))
2307 && !(fixed_scalar == x && !aliases_everything_p (mem)));
2310 /* Anti dependence: X is written after read in MEM takes place. */
2313 anti_dependence (rtx mem, rtx x)
2315 return write_dependence_p (mem, x, /*writep=*/0, /*constp*/1);
2318 /* Output dependence: X is written after store in MEM takes place. */
2321 output_dependence (rtx mem, rtx x)
2323 return write_dependence_p (mem, x, /*writep=*/1, /*constp*/1);
2326 /* Unchanging anti dependence: Like anti_dependence but ignores
2327 the UNCHANGING_RTX_P property on const variable references. */
2330 unchanging_anti_dependence (rtx mem, rtx x)
2332 return write_dependence_p (mem, x, /*writep=*/0, /*constp*/0);
2335 /* A subroutine of nonlocal_mentioned_p, returns 1 if *LOC mentions
2336 something which is not local to the function and is not constant. */
2339 nonlocal_mentioned_p_1 (rtx *loc, void *data ATTRIBUTE_UNUSED)
2348 switch (GET_CODE (x))
2351 if (GET_CODE (SUBREG_REG (x)) == REG)
2353 /* Global registers are not local. */
2354 if (REGNO (SUBREG_REG (x)) < FIRST_PSEUDO_REGISTER
2355 && global_regs[subreg_regno (x)])
2363 /* Global registers are not local. */
2364 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2379 /* Constants in the function's constants pool are constant. */
2380 if (CONSTANT_POOL_ADDRESS_P (x))
2385 /* Non-constant calls and recursion are not local. */
2389 /* Be overly conservative and consider any volatile memory
2390 reference as not local. */
2391 if (MEM_VOLATILE_P (x))
2393 base = find_base_term (XEXP (x, 0));
2396 /* A Pmode ADDRESS could be a reference via the structure value
2397 address or static chain. Such memory references are nonlocal.
2399 Thus, we have to examine the contents of the ADDRESS to find
2400 out if this is a local reference or not. */
2401 if (GET_CODE (base) == ADDRESS
2402 && GET_MODE (base) == Pmode
2403 && (XEXP (base, 0) == stack_pointer_rtx
2404 || XEXP (base, 0) == arg_pointer_rtx
2405 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2406 || XEXP (base, 0) == hard_frame_pointer_rtx
2408 || XEXP (base, 0) == frame_pointer_rtx))
2410 /* Constants in the function's constant pool are constant. */
2411 if (GET_CODE (base) == SYMBOL_REF && CONSTANT_POOL_ADDRESS_P (base))
2416 case UNSPEC_VOLATILE:
2421 if (MEM_VOLATILE_P (x))
2433 /* Returns nonzero if X might mention something which is not
2434 local to the function and is not constant. */
2437 nonlocal_mentioned_p (rtx x)
2441 if (GET_CODE (x) == CALL_INSN)
2443 if (! CONST_OR_PURE_CALL_P (x))
2445 x = CALL_INSN_FUNCTION_USAGE (x);
2453 return for_each_rtx (&x, nonlocal_mentioned_p_1, NULL);
2456 /* A subroutine of nonlocal_referenced_p, returns 1 if *LOC references
2457 something which is not local to the function and is not constant. */
2460 nonlocal_referenced_p_1 (rtx *loc, void *data ATTRIBUTE_UNUSED)
2467 switch (GET_CODE (x))
2473 return nonlocal_mentioned_p (x);
2476 /* Non-constant calls and recursion are not local. */
2480 if (nonlocal_mentioned_p (SET_SRC (x)))
2483 if (GET_CODE (SET_DEST (x)) == MEM)
2484 return nonlocal_mentioned_p (XEXP (SET_DEST (x), 0));
2486 /* If the destination is anything other than a CC0, PC,
2487 MEM, REG, or a SUBREG of a REG that occupies all of
2488 the REG, then X references nonlocal memory if it is
2489 mentioned in the destination. */
2490 if (GET_CODE (SET_DEST (x)) != CC0
2491 && GET_CODE (SET_DEST (x)) != PC
2492 && GET_CODE (SET_DEST (x)) != REG
2493 && ! (GET_CODE (SET_DEST (x)) == SUBREG
2494 && GET_CODE (SUBREG_REG (SET_DEST (x))) == REG
2495 && (((GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (x))))
2496 + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD)
2497 == ((GET_MODE_SIZE (GET_MODE (SET_DEST (x)))
2498 + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD))))
2499 return nonlocal_mentioned_p (SET_DEST (x));
2503 if (GET_CODE (XEXP (x, 0)) == MEM)
2504 return nonlocal_mentioned_p (XEXP (XEXP (x, 0), 0));
2508 return nonlocal_mentioned_p (XEXP (x, 0));
2511 case UNSPEC_VOLATILE:
2515 if (MEM_VOLATILE_P (x))
2527 /* Returns nonzero if X might reference something which is not
2528 local to the function and is not constant. */
2531 nonlocal_referenced_p (rtx x)
2535 if (GET_CODE (x) == CALL_INSN)
2537 if (! CONST_OR_PURE_CALL_P (x))
2539 x = CALL_INSN_FUNCTION_USAGE (x);
2547 return for_each_rtx (&x, nonlocal_referenced_p_1, NULL);
2550 /* A subroutine of nonlocal_set_p, returns 1 if *LOC sets
2551 something which is not local to the function and is not constant. */
2554 nonlocal_set_p_1 (rtx *loc, void *data ATTRIBUTE_UNUSED)
2561 switch (GET_CODE (x))
2564 /* Non-constant calls and recursion are not local. */
2573 return nonlocal_mentioned_p (XEXP (x, 0));
2576 if (nonlocal_mentioned_p (SET_DEST (x)))
2578 return nonlocal_set_p (SET_SRC (x));
2581 return nonlocal_mentioned_p (XEXP (x, 0));
2587 case UNSPEC_VOLATILE:
2591 if (MEM_VOLATILE_P (x))
2603 /* Returns nonzero if X might set something which is not
2604 local to the function and is not constant. */
2607 nonlocal_set_p (rtx x)
2611 if (GET_CODE (x) == CALL_INSN)
2613 if (! CONST_OR_PURE_CALL_P (x))
2615 x = CALL_INSN_FUNCTION_USAGE (x);
2623 return for_each_rtx (&x, nonlocal_set_p_1, NULL);
2626 /* Mark the function if it is pure or constant. */
2629 mark_constant_function (void)
2632 int nonlocal_memory_referenced;
2634 if (TREE_READONLY (current_function_decl)
2635 || DECL_IS_PURE (current_function_decl)
2636 || TREE_THIS_VOLATILE (current_function_decl)
2637 || current_function_has_nonlocal_goto
2638 || !(*targetm.binds_local_p) (current_function_decl))
2641 /* A loop might not return which counts as a side effect. */
2642 if (mark_dfs_back_edges ())
2645 nonlocal_memory_referenced = 0;
2647 init_alias_analysis ();
2649 /* Determine if this is a constant or pure function. */
2651 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2653 if (! INSN_P (insn))
2656 if (nonlocal_set_p (insn) || global_reg_mentioned_p (insn)
2657 || volatile_refs_p (PATTERN (insn)))
2660 if (! nonlocal_memory_referenced)
2661 nonlocal_memory_referenced = nonlocal_referenced_p (insn);
2664 end_alias_analysis ();
2666 /* Mark the function. */
2670 else if (nonlocal_memory_referenced)
2672 cgraph_rtl_info (current_function_decl)->pure_function = 1;
2673 DECL_IS_PURE (current_function_decl) = 1;
2677 cgraph_rtl_info (current_function_decl)->const_function = 1;
2678 TREE_READONLY (current_function_decl) = 1;
2684 init_alias_once (void)
2688 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2689 /* Check whether this register can hold an incoming pointer
2690 argument. FUNCTION_ARG_REGNO_P tests outgoing register
2691 numbers, so translate if necessary due to register windows. */
2692 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i))
2693 && HARD_REGNO_MODE_OK (i, Pmode))
2694 static_reg_base_value[i]
2695 = gen_rtx_ADDRESS (VOIDmode, gen_rtx_REG (Pmode, i));
2697 static_reg_base_value[STACK_POINTER_REGNUM]
2698 = gen_rtx_ADDRESS (Pmode, stack_pointer_rtx);
2699 static_reg_base_value[ARG_POINTER_REGNUM]
2700 = gen_rtx_ADDRESS (Pmode, arg_pointer_rtx);
2701 static_reg_base_value[FRAME_POINTER_REGNUM]
2702 = gen_rtx_ADDRESS (Pmode, frame_pointer_rtx);
2703 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2704 static_reg_base_value[HARD_FRAME_POINTER_REGNUM]
2705 = gen_rtx_ADDRESS (Pmode, hard_frame_pointer_rtx);
2709 /* Set MEMORY_MODIFIED when X modifies DATA (that is assumed
2710 to be memory reference. */
2711 static bool memory_modified;
2713 memory_modified_1 (rtx x, rtx pat ATTRIBUTE_UNUSED, void *data)
2715 if (GET_CODE (x) == MEM)
2717 if (anti_dependence (x, (rtx)data) || output_dependence (x, (rtx)data))
2718 memory_modified = true;
2723 /* Return true when INSN possibly modify memory contents of MEM
2724 (ie address can be modified). */
2726 memory_modified_in_insn_p (rtx mem, rtx insn)
2730 memory_modified = false;
2731 note_stores (PATTERN (insn), memory_modified_1, mem);
2732 return memory_modified;
2735 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
2739 init_alias_analysis (void)
2741 unsigned int maxreg = max_reg_num ();
2747 timevar_push (TV_ALIAS_ANALYSIS);
2749 reg_known_value_size = maxreg;
2752 = (rtx *) xcalloc ((maxreg - FIRST_PSEUDO_REGISTER), sizeof (rtx))
2753 - FIRST_PSEUDO_REGISTER;
2755 = (char*) xcalloc ((maxreg - FIRST_PSEUDO_REGISTER), sizeof (char))
2756 - FIRST_PSEUDO_REGISTER;
2758 /* Overallocate reg_base_value to allow some growth during loop
2759 optimization. Loop unrolling can create a large number of
2761 if (old_reg_base_value)
2763 reg_base_value = old_reg_base_value;
2764 /* If varray gets large zeroing cost may get important. */
2765 if (VARRAY_SIZE (reg_base_value) > 256
2766 && VARRAY_SIZE (reg_base_value) > 4 * maxreg)
2767 VARRAY_GROW (reg_base_value, maxreg);
2768 VARRAY_CLEAR (reg_base_value);
2769 if (VARRAY_SIZE (reg_base_value) < maxreg)
2770 VARRAY_GROW (reg_base_value, maxreg);
2774 VARRAY_RTX_INIT (reg_base_value, maxreg, "reg_base_value");
2777 new_reg_base_value = xmalloc (maxreg * sizeof (rtx));
2778 reg_seen = xmalloc (maxreg);
2779 if (! reload_completed && flag_old_unroll_loops)
2781 /* ??? Why are we realloc'ing if we're just going to zero it? */
2782 alias_invariant = xrealloc (alias_invariant,
2783 maxreg * sizeof (rtx));
2784 memset (alias_invariant, 0, maxreg * sizeof (rtx));
2785 alias_invariant_size = maxreg;
2788 /* The basic idea is that each pass through this loop will use the
2789 "constant" information from the previous pass to propagate alias
2790 information through another level of assignments.
2792 This could get expensive if the assignment chains are long. Maybe
2793 we should throttle the number of iterations, possibly based on
2794 the optimization level or flag_expensive_optimizations.
2796 We could propagate more information in the first pass by making use
2797 of REG_N_SETS to determine immediately that the alias information
2798 for a pseudo is "constant".
2800 A program with an uninitialized variable can cause an infinite loop
2801 here. Instead of doing a full dataflow analysis to detect such problems
2802 we just cap the number of iterations for the loop.
2804 The state of the arrays for the set chain in question does not matter
2805 since the program has undefined behavior. */
2810 /* Assume nothing will change this iteration of the loop. */
2813 /* We want to assign the same IDs each iteration of this loop, so
2814 start counting from zero each iteration of the loop. */
2817 /* We're at the start of the function each iteration through the
2818 loop, so we're copying arguments. */
2819 copying_arguments = true;
2821 /* Wipe the potential alias information clean for this pass. */
2822 memset (new_reg_base_value, 0, maxreg * sizeof (rtx));
2824 /* Wipe the reg_seen array clean. */
2825 memset (reg_seen, 0, maxreg);
2827 /* Mark all hard registers which may contain an address.
2828 The stack, frame and argument pointers may contain an address.
2829 An argument register which can hold a Pmode value may contain
2830 an address even if it is not in BASE_REGS.
2832 The address expression is VOIDmode for an argument and
2833 Pmode for other registers. */
2835 memcpy (new_reg_base_value, static_reg_base_value,
2836 FIRST_PSEUDO_REGISTER * sizeof (rtx));
2838 /* Walk the insns adding values to the new_reg_base_value array. */
2839 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2845 #if defined (HAVE_prologue) || defined (HAVE_epilogue)
2846 /* The prologue/epilogue insns are not threaded onto the
2847 insn chain until after reload has completed. Thus,
2848 there is no sense wasting time checking if INSN is in
2849 the prologue/epilogue until after reload has completed. */
2850 if (reload_completed
2851 && prologue_epilogue_contains (insn))
2855 /* If this insn has a noalias note, process it, Otherwise,
2856 scan for sets. A simple set will have no side effects
2857 which could change the base value of any other register. */
2859 if (GET_CODE (PATTERN (insn)) == SET
2860 && REG_NOTES (insn) != 0
2861 && find_reg_note (insn, REG_NOALIAS, NULL_RTX))
2862 record_set (SET_DEST (PATTERN (insn)), NULL_RTX, NULL);
2864 note_stores (PATTERN (insn), record_set, NULL);
2866 set = single_set (insn);
2869 && GET_CODE (SET_DEST (set)) == REG
2870 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER)
2872 unsigned int regno = REGNO (SET_DEST (set));
2873 rtx src = SET_SRC (set);
2875 if (REG_NOTES (insn) != 0
2876 && (((note = find_reg_note (insn, REG_EQUAL, 0)) != 0
2877 && REG_N_SETS (regno) == 1)
2878 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) != 0)
2879 && GET_CODE (XEXP (note, 0)) != EXPR_LIST
2880 && ! rtx_varies_p (XEXP (note, 0), 1)
2881 && ! reg_overlap_mentioned_p (SET_DEST (set), XEXP (note, 0)))
2883 reg_known_value[regno] = XEXP (note, 0);
2884 reg_known_equiv_p[regno] = REG_NOTE_KIND (note) == REG_EQUIV;
2886 else if (REG_N_SETS (regno) == 1
2887 && GET_CODE (src) == PLUS
2888 && GET_CODE (XEXP (src, 0)) == REG
2889 && REGNO (XEXP (src, 0)) >= FIRST_PSEUDO_REGISTER
2890 && (reg_known_value[REGNO (XEXP (src, 0))])
2891 && GET_CODE (XEXP (src, 1)) == CONST_INT)
2893 rtx op0 = XEXP (src, 0);
2894 op0 = reg_known_value[REGNO (op0)];
2895 reg_known_value[regno]
2896 = plus_constant (op0, INTVAL (XEXP (src, 1)));
2897 reg_known_equiv_p[regno] = 0;
2899 else if (REG_N_SETS (regno) == 1
2900 && ! rtx_varies_p (src, 1))
2902 reg_known_value[regno] = src;
2903 reg_known_equiv_p[regno] = 0;
2907 else if (GET_CODE (insn) == NOTE
2908 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_BEG)
2909 copying_arguments = false;
2912 /* Now propagate values from new_reg_base_value to reg_base_value. */
2913 if (maxreg != (unsigned int) max_reg_num())
2915 for (ui = 0; ui < maxreg; ui++)
2917 if (new_reg_base_value[ui]
2918 && new_reg_base_value[ui] != VARRAY_RTX (reg_base_value, ui)
2919 && ! rtx_equal_p (new_reg_base_value[ui],
2920 VARRAY_RTX (reg_base_value, ui)))
2922 VARRAY_RTX (reg_base_value, ui) = new_reg_base_value[ui];
2927 while (changed && ++pass < MAX_ALIAS_LOOP_PASSES);
2929 /* Fill in the remaining entries. */
2930 for (i = FIRST_PSEUDO_REGISTER; i < (int)maxreg; i++)
2931 if (reg_known_value[i] == 0)
2932 reg_known_value[i] = regno_reg_rtx[i];
2934 /* Simplify the reg_base_value array so that no register refers to
2935 another register, except to special registers indirectly through
2936 ADDRESS expressions.
2938 In theory this loop can take as long as O(registers^2), but unless
2939 there are very long dependency chains it will run in close to linear
2942 This loop may not be needed any longer now that the main loop does
2943 a better job at propagating alias information. */
2949 for (ui = 0; ui < maxreg; ui++)
2951 rtx base = VARRAY_RTX (reg_base_value, ui);
2952 if (base && GET_CODE (base) == REG)
2954 unsigned int base_regno = REGNO (base);
2955 if (base_regno == ui) /* register set from itself */
2956 VARRAY_RTX (reg_base_value, ui) = 0;
2958 VARRAY_RTX (reg_base_value, ui)
2959 = VARRAY_RTX (reg_base_value, base_regno);
2964 while (changed && pass < MAX_ALIAS_LOOP_PASSES);
2967 free (new_reg_base_value);
2968 new_reg_base_value = 0;
2971 timevar_pop (TV_ALIAS_ANALYSIS);
2975 end_alias_analysis (void)
2977 old_reg_base_value = reg_base_value;
2978 free (reg_known_value + FIRST_PSEUDO_REGISTER);
2979 reg_known_value = 0;
2980 reg_known_value_size = 0;
2981 free (reg_known_equiv_p + FIRST_PSEUDO_REGISTER);
2982 reg_known_equiv_p = 0;
2983 if (alias_invariant)
2985 free (alias_invariant);
2986 alias_invariant = 0;
2987 alias_invariant_size = 0;
2991 #include "gt-alias.h"