1 /* Alias analysis for GNU C
2 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
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"
46 /* The alias sets assigned to MEMs assist the back-end in determining
47 which MEMs can alias which other MEMs. In general, two MEMs in
48 different alias sets cannot alias each other, with one important
49 exception. Consider something like:
51 struct S {int i; double d; };
53 a store to an `S' can alias something of either type `int' or type
54 `double'. (However, a store to an `int' cannot alias a `double'
55 and vice versa.) We indicate this via a tree structure that looks
63 (The arrows are directed and point downwards.)
64 In this situation we say the alias set for `struct S' is the
65 `superset' and that those for `int' and `double' are `subsets'.
67 To see whether two alias sets can point to the same memory, we must
68 see if either alias set is a subset of the other. We need not trace
69 past immediate descendants, however, since we propagate all
70 grandchildren up one level.
72 Alias set zero is implicitly a superset of all other alias sets.
73 However, this is no actual entry for alias set zero. It is an
74 error to attempt to explicitly construct a subset of zero. */
76 typedef struct alias_set_entry
78 /* The alias set number, as stored in MEM_ALIAS_SET. */
79 HOST_WIDE_INT alias_set;
81 /* The children of the alias set. These are not just the immediate
82 children, but, in fact, all descendants. So, if we have:
84 struct T { struct S s; float f; }
86 continuing our example above, the children here will be all of
87 `int', `double', `float', and `struct S'. */
90 /* Nonzero if would have a child of zero: this effectively makes this
91 alias set the same as alias set zero. */
95 static int rtx_equal_for_memref_p PARAMS ((rtx, rtx));
96 static rtx find_symbolic_term PARAMS ((rtx));
97 rtx get_addr PARAMS ((rtx));
98 static int memrefs_conflict_p PARAMS ((int, rtx, int, rtx,
100 static void record_set PARAMS ((rtx, rtx, void *));
101 static rtx find_base_term PARAMS ((rtx));
102 static int base_alias_check PARAMS ((rtx, rtx, enum machine_mode,
104 static rtx find_base_value PARAMS ((rtx));
105 static int mems_in_disjoint_alias_sets_p PARAMS ((rtx, rtx));
106 static int insert_subset_children PARAMS ((splay_tree_node, void*));
107 static tree find_base_decl PARAMS ((tree));
108 static alias_set_entry get_alias_set_entry PARAMS ((HOST_WIDE_INT));
109 static rtx fixed_scalar_and_varying_struct_p PARAMS ((rtx, rtx, rtx, rtx,
110 int (*) (rtx, int)));
111 static int aliases_everything_p PARAMS ((rtx));
112 static bool nonoverlapping_component_refs_p PARAMS ((tree, tree));
113 static tree decl_for_component_ref PARAMS ((tree));
114 static rtx adjust_offset_for_component_ref PARAMS ((tree, rtx));
115 static int nonoverlapping_memrefs_p PARAMS ((rtx, rtx));
116 static int write_dependence_p PARAMS ((rtx, rtx, int));
118 static int nonlocal_mentioned_p_1 PARAMS ((rtx *, void *));
119 static int nonlocal_mentioned_p PARAMS ((rtx));
120 static int nonlocal_referenced_p_1 PARAMS ((rtx *, void *));
121 static int nonlocal_referenced_p PARAMS ((rtx));
122 static int nonlocal_set_p_1 PARAMS ((rtx *, void *));
123 static int nonlocal_set_p PARAMS ((rtx));
124 static void memory_modified_1 PARAMS ((rtx, rtx, void *));
126 /* Set up all info needed to perform alias analysis on memory references. */
128 /* Returns the size in bytes of the mode of X. */
129 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
131 /* Returns nonzero if MEM1 and MEM2 do not alias because they are in
132 different alias sets. We ignore alias sets in functions making use
133 of variable arguments because the va_arg macros on some systems are
135 #define DIFFERENT_ALIAS_SETS_P(MEM1, MEM2) \
136 mems_in_disjoint_alias_sets_p (MEM1, MEM2)
138 /* Cap the number of passes we make over the insns propagating alias
139 information through set chains. 10 is a completely arbitrary choice. */
140 #define MAX_ALIAS_LOOP_PASSES 10
142 /* reg_base_value[N] gives an address to which register N is related.
143 If all sets after the first add or subtract to the current value
144 or otherwise modify it so it does not point to a different top level
145 object, reg_base_value[N] is equal to the address part of the source
148 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
149 expressions represent certain special values: function arguments and
150 the stack, frame, and argument pointers.
152 The contents of an ADDRESS is not normally used, the mode of the
153 ADDRESS determines whether the ADDRESS is a function argument or some
154 other special value. Pointer equality, not rtx_equal_p, determines whether
155 two ADDRESS expressions refer to the same base address.
157 The only use of the contents of an ADDRESS is for determining if the
158 current function performs nonlocal memory memory references for the
159 purposes of marking the function as a constant function. */
161 static GTY((length ("reg_base_value_size"))) rtx *reg_base_value;
162 static rtx *new_reg_base_value;
163 static unsigned int reg_base_value_size; /* size of reg_base_value array */
165 /* Static hunks of RTL used by the aliasing code; these are initialized
166 once per function to avoid unnecessary RTL allocations. */
167 static GTY (()) rtx static_reg_base_value[FIRST_PSEUDO_REGISTER];
169 #define REG_BASE_VALUE(X) \
170 (REGNO (X) < reg_base_value_size \
171 ? reg_base_value[REGNO (X)] : 0)
173 /* Vector of known invariant relationships between registers. Set in
174 loop unrolling. Indexed by register number, if nonzero the value
175 is an expression describing this register in terms of another.
177 The length of this array is REG_BASE_VALUE_SIZE.
179 Because this array contains only pseudo registers it has no effect
181 static rtx *alias_invariant;
183 /* Vector indexed by N giving the initial (unchanging) value known for
184 pseudo-register N. This array is initialized in
185 init_alias_analysis, and does not change until end_alias_analysis
187 rtx *reg_known_value;
189 /* Indicates number of valid entries in reg_known_value. */
190 static unsigned int reg_known_value_size;
192 /* Vector recording for each reg_known_value whether it is due to a
193 REG_EQUIV note. Future passes (viz., reload) may replace the
194 pseudo with the equivalent expression and so we account for the
195 dependences that would be introduced if that happens.
197 The REG_EQUIV notes created in assign_parms may mention the arg
198 pointer, and there are explicit insns in the RTL that modify the
199 arg pointer. Thus we must ensure that such insns don't get
200 scheduled across each other because that would invalidate the
201 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
202 wrong, but solving the problem in the scheduler will likely give
203 better code, so we do it here. */
204 char *reg_known_equiv_p;
206 /* True when scanning insns from the start of the rtl to the
207 NOTE_INSN_FUNCTION_BEG note. */
208 static bool copying_arguments;
210 /* The splay-tree used to store the various alias set entries. */
211 static splay_tree alias_sets;
213 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
214 such an entry, or NULL otherwise. */
216 static alias_set_entry
217 get_alias_set_entry (alias_set)
218 HOST_WIDE_INT alias_set;
221 = splay_tree_lookup (alias_sets, (splay_tree_key) alias_set);
223 return sn != 0 ? ((alias_set_entry) sn->value) : 0;
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 (mem1, mem2)
234 #ifdef ENABLE_CHECKING
235 /* Perform a basic sanity check. Namely, that there are no alias sets
236 if we're not using strict aliasing. This helps to catch bugs
237 whereby someone uses PUT_CODE, but doesn't clear MEM_ALIAS_SET, or
238 where a MEM is allocated in some way other than by the use of
239 gen_rtx_MEM, and the MEM_ALIAS_SET is not cleared. If we begin to
240 use alias sets to indicate that spilled registers cannot alias each
241 other, we might need to remove this check. */
242 if (! flag_strict_aliasing
243 && (MEM_ALIAS_SET (mem1) != 0 || MEM_ALIAS_SET (mem2) != 0))
247 return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1), MEM_ALIAS_SET (mem2));
250 /* Insert the NODE into the splay tree given by DATA. Used by
251 record_alias_subset via splay_tree_foreach. */
254 insert_subset_children (node, data)
255 splay_tree_node node;
258 splay_tree_insert ((splay_tree) data, node->key, node->value);
263 /* Return 1 if the two specified alias sets may conflict. */
266 alias_sets_conflict_p (set1, set2)
267 HOST_WIDE_INT set1, set2;
271 /* If have no alias set information for one of the operands, we have
272 to assume it can alias anything. */
273 if (set1 == 0 || set2 == 0
274 /* If the two alias sets are the same, they may alias. */
278 /* See if the first alias set is a subset of the second. */
279 ase = get_alias_set_entry (set1);
281 && (ase->has_zero_child
282 || splay_tree_lookup (ase->children,
283 (splay_tree_key) set2)))
286 /* Now do the same, but with the alias sets reversed. */
287 ase = get_alias_set_entry (set2);
289 && (ase->has_zero_child
290 || splay_tree_lookup (ase->children,
291 (splay_tree_key) set1)))
294 /* The two alias sets are distinct and neither one is the
295 child of the other. Therefore, they cannot alias. */
299 /* Return 1 if TYPE is a RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE and has
300 has any readonly fields. If any of the fields have types that
301 contain readonly fields, return true as well. */
304 readonly_fields_p (type)
309 if (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
310 && TREE_CODE (type) != QUAL_UNION_TYPE)
313 for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field))
314 if (TREE_CODE (field) == FIELD_DECL
315 && (TREE_READONLY (field)
316 || readonly_fields_p (TREE_TYPE (field))))
322 /* Return 1 if any MEM object of type T1 will always conflict (using the
323 dependency routines in this file) with any MEM object of type T2.
324 This is used when allocating temporary storage. If T1 and/or T2 are
325 NULL_TREE, it means we know nothing about the storage. */
328 objects_must_conflict_p (t1, t2)
331 /* If neither has a type specified, we don't know if they'll conflict
332 because we may be using them to store objects of various types, for
333 example the argument and local variables areas of inlined functions. */
334 if (t1 == 0 && t2 == 0)
337 /* If one or the other has readonly fields or is readonly,
338 then they may not conflict. */
339 if ((t1 != 0 && readonly_fields_p (t1))
340 || (t2 != 0 && readonly_fields_p (t2))
341 || (t1 != 0 && lang_hooks.honor_readonly && TYPE_READONLY (t1))
342 || (t2 != 0 && lang_hooks.honor_readonly && TYPE_READONLY (t2)))
345 /* If they are the same type, they must conflict. */
347 /* Likewise if both are volatile. */
348 || (t1 != 0 && TYPE_VOLATILE (t1) && t2 != 0 && TYPE_VOLATILE (t2)))
351 /* If one is aggregate and the other is scalar then they may not
353 if ((t1 != 0 && AGGREGATE_TYPE_P (t1))
354 != (t2 != 0 && AGGREGATE_TYPE_P (t2)))
357 /* Otherwise they conflict only if the alias sets conflict. */
358 return alias_sets_conflict_p (t1 ? get_alias_set (t1) : 0,
359 t2 ? get_alias_set (t2) : 0);
362 /* T is an expression with pointer type. Find the DECL on which this
363 expression is based. (For example, in `a[i]' this would be `a'.)
364 If there is no such DECL, or a unique decl cannot be determined,
365 NULL_TREE is returned. */
373 if (t == 0 || t == error_mark_node || ! POINTER_TYPE_P (TREE_TYPE (t)))
376 /* If this is a declaration, return it. */
377 if (TREE_CODE_CLASS (TREE_CODE (t)) == 'd')
380 /* Handle general expressions. It would be nice to deal with
381 COMPONENT_REFs here. If we could tell that `a' and `b' were the
382 same, then `a->f' and `b->f' are also the same. */
383 switch (TREE_CODE_CLASS (TREE_CODE (t)))
386 return find_base_decl (TREE_OPERAND (t, 0));
389 /* Return 0 if found in neither or both are the same. */
390 d0 = find_base_decl (TREE_OPERAND (t, 0));
391 d1 = find_base_decl (TREE_OPERAND (t, 1));
402 d0 = find_base_decl (TREE_OPERAND (t, 0));
403 d1 = find_base_decl (TREE_OPERAND (t, 1));
404 d2 = find_base_decl (TREE_OPERAND (t, 2));
406 /* Set any nonzero values from the last, then from the first. */
407 if (d1 == 0) d1 = d2;
408 if (d0 == 0) d0 = d1;
409 if (d1 == 0) d1 = d0;
410 if (d2 == 0) d2 = d1;
412 /* At this point all are nonzero or all are zero. If all three are the
413 same, return it. Otherwise, return zero. */
414 return (d0 == d1 && d1 == d2) ? d0 : 0;
421 /* Return 1 if all the nested component references handled by
422 get_inner_reference in T are such that we can address the object in T. */
428 /* If we're at the end, it is vacuously addressable. */
429 if (! handled_component_p (t))
432 /* Bitfields are never addressable. */
433 else if (TREE_CODE (t) == BIT_FIELD_REF)
436 /* Fields are addressable unless they are marked as nonaddressable or
437 the containing type has alias set 0. */
438 else if (TREE_CODE (t) == COMPONENT_REF
439 && ! DECL_NONADDRESSABLE_P (TREE_OPERAND (t, 1))
440 && get_alias_set (TREE_TYPE (TREE_OPERAND (t, 0))) != 0
441 && can_address_p (TREE_OPERAND (t, 0)))
444 /* Likewise for arrays. */
445 else if ((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
446 && ! TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t, 0)))
447 && get_alias_set (TREE_TYPE (TREE_OPERAND (t, 0))) != 0
448 && can_address_p (TREE_OPERAND (t, 0)))
454 /* Return the alias set for T, which may be either a type or an
455 expression. Call language-specific routine for help, if needed. */
463 /* If we're not doing any alias analysis, just assume everything
464 aliases everything else. Also return 0 if this or its type is
466 if (! flag_strict_aliasing || t == error_mark_node
468 && (TREE_TYPE (t) == 0 || TREE_TYPE (t) == error_mark_node)))
471 /* We can be passed either an expression or a type. This and the
472 language-specific routine may make mutually-recursive calls to each other
473 to figure out what to do. At each juncture, we see if this is a tree
474 that the language may need to handle specially. First handle things that
479 tree placeholder_ptr = 0;
481 /* Remove any nops, then give the language a chance to do
482 something with this tree before we look at it. */
484 set = (*lang_hooks.get_alias_set) (t);
488 /* First see if the actual object referenced is an INDIRECT_REF from a
489 restrict-qualified pointer or a "void *". Replace
490 PLACEHOLDER_EXPRs. */
491 while (TREE_CODE (inner) == PLACEHOLDER_EXPR
492 || handled_component_p (inner))
494 if (TREE_CODE (inner) == PLACEHOLDER_EXPR)
495 inner = find_placeholder (inner, &placeholder_ptr);
497 inner = TREE_OPERAND (inner, 0);
502 /* Check for accesses through restrict-qualified pointers. */
503 if (TREE_CODE (inner) == INDIRECT_REF)
505 tree decl = find_base_decl (TREE_OPERAND (inner, 0));
507 if (decl && DECL_POINTER_ALIAS_SET_KNOWN_P (decl))
509 /* If we haven't computed the actual alias set, do it now. */
510 if (DECL_POINTER_ALIAS_SET (decl) == -2)
512 /* No two restricted pointers can point at the same thing.
513 However, a restricted pointer can point at the same thing
514 as an unrestricted pointer, if that unrestricted pointer
515 is based on the restricted pointer. So, we make the
516 alias set for the restricted pointer a subset of the
517 alias set for the type pointed to by the type of the
519 HOST_WIDE_INT pointed_to_alias_set
520 = get_alias_set (TREE_TYPE (TREE_TYPE (decl)));
522 if (pointed_to_alias_set == 0)
523 /* It's not legal to make a subset of alias set zero. */
527 DECL_POINTER_ALIAS_SET (decl) = new_alias_set ();
528 record_alias_subset (pointed_to_alias_set,
529 DECL_POINTER_ALIAS_SET (decl));
533 /* We use the alias set indicated in the declaration. */
534 return DECL_POINTER_ALIAS_SET (decl);
537 /* If we have an INDIRECT_REF via a void pointer, we don't
538 know anything about what that might alias. */
539 else if (TREE_CODE (TREE_TYPE (inner)) == VOID_TYPE)
543 /* Otherwise, pick up the outermost object that we could have a pointer
544 to, processing conversion and PLACEHOLDER_EXPR as above. */
546 while (TREE_CODE (t) == PLACEHOLDER_EXPR
547 || (handled_component_p (t) && ! can_address_p (t)))
549 if (TREE_CODE (t) == PLACEHOLDER_EXPR)
550 t = find_placeholder (t, &placeholder_ptr);
552 t = TREE_OPERAND (t, 0);
557 /* If we've already determined the alias set for a decl, just return
558 it. This is necessary for C++ anonymous unions, whose component
559 variables don't look like union members (boo!). */
560 if (TREE_CODE (t) == VAR_DECL
561 && DECL_RTL_SET_P (t) && GET_CODE (DECL_RTL (t)) == MEM)
562 return MEM_ALIAS_SET (DECL_RTL (t));
564 /* Now all we care about is the type. */
568 /* Variant qualifiers don't affect the alias set, so get the main
569 variant. If this is a type with a known alias set, return it. */
570 t = TYPE_MAIN_VARIANT (t);
571 if (TYPE_ALIAS_SET_KNOWN_P (t))
572 return TYPE_ALIAS_SET (t);
574 /* See if the language has special handling for this type. */
575 set = (*lang_hooks.get_alias_set) (t);
579 /* There are no objects of FUNCTION_TYPE, so there's no point in
580 using up an alias set for them. (There are, of course, pointers
581 and references to functions, but that's different.) */
582 else if (TREE_CODE (t) == FUNCTION_TYPE)
585 /* Unless the language specifies otherwise, let vector types alias
586 their components. This avoids some nasty type punning issues in
587 normal usage. And indeed lets vectors be treated more like an
589 else if (TREE_CODE (t) == VECTOR_TYPE)
590 set = get_alias_set (TREE_TYPE (t));
593 /* Otherwise make a new alias set for this type. */
594 set = new_alias_set ();
596 TYPE_ALIAS_SET (t) = set;
598 /* If this is an aggregate type, we must record any component aliasing
600 if (AGGREGATE_TYPE_P (t) || TREE_CODE (t) == COMPLEX_TYPE)
601 record_component_aliases (t);
606 /* Return a brand-new alias set. */
611 static HOST_WIDE_INT last_alias_set;
613 if (flag_strict_aliasing)
614 return ++last_alias_set;
619 /* Indicate that things in SUBSET can alias things in SUPERSET, but
620 not vice versa. For example, in C, a store to an `int' can alias a
621 structure containing an `int', but not vice versa. Here, the
622 structure would be the SUPERSET and `int' the SUBSET. This
623 function should be called only once per SUPERSET/SUBSET pair.
625 It is illegal for SUPERSET to be zero; everything is implicitly a
626 subset of alias set zero. */
629 record_alias_subset (superset, subset)
630 HOST_WIDE_INT superset;
631 HOST_WIDE_INT subset;
633 alias_set_entry superset_entry;
634 alias_set_entry subset_entry;
636 /* It is possible in complex type situations for both sets to be the same,
637 in which case we can ignore this operation. */
638 if (superset == subset)
644 superset_entry = get_alias_set_entry (superset);
645 if (superset_entry == 0)
647 /* Create an entry for the SUPERSET, so that we have a place to
648 attach the SUBSET. */
650 = (alias_set_entry) xmalloc (sizeof (struct alias_set_entry));
651 superset_entry->alias_set = superset;
652 superset_entry->children
653 = splay_tree_new (splay_tree_compare_ints, 0, 0);
654 superset_entry->has_zero_child = 0;
655 splay_tree_insert (alias_sets, (splay_tree_key) superset,
656 (splay_tree_value) superset_entry);
660 superset_entry->has_zero_child = 1;
663 subset_entry = get_alias_set_entry (subset);
664 /* If there is an entry for the subset, enter all of its children
665 (if they are not already present) as children of the SUPERSET. */
668 if (subset_entry->has_zero_child)
669 superset_entry->has_zero_child = 1;
671 splay_tree_foreach (subset_entry->children, insert_subset_children,
672 superset_entry->children);
675 /* Enter the SUBSET itself as a child of the SUPERSET. */
676 splay_tree_insert (superset_entry->children,
677 (splay_tree_key) subset, 0);
681 /* Record that component types of TYPE, if any, are part of that type for
682 aliasing purposes. For record types, we only record component types
683 for fields that are marked addressable. For array types, we always
684 record the component types, so the front end should not call this
685 function if the individual component aren't addressable. */
688 record_component_aliases (type)
691 HOST_WIDE_INT superset = get_alias_set (type);
697 switch (TREE_CODE (type))
700 if (! TYPE_NONALIASED_COMPONENT (type))
701 record_alias_subset (superset, get_alias_set (TREE_TYPE (type)));
706 case QUAL_UNION_TYPE:
707 /* Recursively record aliases for the base classes, if there are any */
708 if (TYPE_BINFO (type) != NULL && TYPE_BINFO_BASETYPES (type) != NULL)
711 for (i = 0; i < TREE_VEC_LENGTH (TYPE_BINFO_BASETYPES (type)); i++)
713 tree binfo = TREE_VEC_ELT (TYPE_BINFO_BASETYPES (type), i);
714 record_alias_subset (superset,
715 get_alias_set (BINFO_TYPE (binfo)));
718 for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field))
719 if (TREE_CODE (field) == FIELD_DECL && ! DECL_NONADDRESSABLE_P (field))
720 record_alias_subset (superset, get_alias_set (TREE_TYPE (field)));
724 record_alias_subset (superset, get_alias_set (TREE_TYPE (type)));
732 /* Allocate an alias set for use in storing and reading from the varargs
736 get_varargs_alias_set ()
738 static HOST_WIDE_INT set = -1;
741 set = new_alias_set ();
746 /* Likewise, but used for the fixed portions of the frame, e.g., register
750 get_frame_alias_set ()
752 static HOST_WIDE_INT set = -1;
755 set = new_alias_set ();
760 /* Inside SRC, the source of a SET, find a base address. */
763 find_base_value (src)
768 switch (GET_CODE (src))
776 /* At the start of a function, argument registers have known base
777 values which may be lost later. Returning an ADDRESS
778 expression here allows optimization based on argument values
779 even when the argument registers are used for other purposes. */
780 if (regno < FIRST_PSEUDO_REGISTER && copying_arguments)
781 return new_reg_base_value[regno];
783 /* If a pseudo has a known base value, return it. Do not do this
784 for non-fixed hard regs since it can result in a circular
785 dependency chain for registers which have values at function entry.
787 The test above is not sufficient because the scheduler may move
788 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
789 if ((regno >= FIRST_PSEUDO_REGISTER || fixed_regs[regno])
790 && regno < reg_base_value_size)
792 /* If we're inside init_alias_analysis, use new_reg_base_value
793 to reduce the number of relaxation iterations. */
794 if (new_reg_base_value && new_reg_base_value[regno]
795 && REG_N_SETS (regno) == 1)
796 return new_reg_base_value[regno];
798 if (reg_base_value[regno])
799 return reg_base_value[regno];
805 /* Check for an argument passed in memory. Only record in the
806 copying-arguments block; it is too hard to track changes
808 if (copying_arguments
809 && (XEXP (src, 0) == arg_pointer_rtx
810 || (GET_CODE (XEXP (src, 0)) == PLUS
811 && XEXP (XEXP (src, 0), 0) == arg_pointer_rtx)))
812 return gen_rtx_ADDRESS (VOIDmode, src);
817 if (GET_CODE (src) != PLUS && GET_CODE (src) != MINUS)
820 /* ... fall through ... */
825 rtx temp, src_0 = XEXP (src, 0), src_1 = XEXP (src, 1);
827 /* If either operand is a REG that is a known pointer, then it
829 if (REG_P (src_0) && REG_POINTER (src_0))
830 return find_base_value (src_0);
831 if (REG_P (src_1) && REG_POINTER (src_1))
832 return find_base_value (src_1);
834 /* If either operand is a REG, then see if we already have
835 a known value for it. */
838 temp = find_base_value (src_0);
845 temp = find_base_value (src_1);
850 /* If either base is named object or a special address
851 (like an argument or stack reference), then use it for the
854 && (GET_CODE (src_0) == SYMBOL_REF
855 || GET_CODE (src_0) == LABEL_REF
856 || (GET_CODE (src_0) == ADDRESS
857 && GET_MODE (src_0) != VOIDmode)))
861 && (GET_CODE (src_1) == SYMBOL_REF
862 || GET_CODE (src_1) == LABEL_REF
863 || (GET_CODE (src_1) == ADDRESS
864 && GET_MODE (src_1) != VOIDmode)))
867 /* Guess which operand is the base address:
868 If either operand is a symbol, then it is the base. If
869 either operand is a CONST_INT, then the other is the base. */
870 if (GET_CODE (src_1) == CONST_INT || CONSTANT_P (src_0))
871 return find_base_value (src_0);
872 else if (GET_CODE (src_0) == CONST_INT || CONSTANT_P (src_1))
873 return find_base_value (src_1);
879 /* The standard form is (lo_sum reg sym) so look only at the
881 return find_base_value (XEXP (src, 1));
884 /* If the second operand is constant set the base
885 address to the first operand. */
886 if (GET_CODE (XEXP (src, 1)) == CONST_INT && INTVAL (XEXP (src, 1)) != 0)
887 return find_base_value (XEXP (src, 0));
891 if (GET_MODE_SIZE (GET_MODE (src)) < GET_MODE_SIZE (Pmode))
901 return find_base_value (XEXP (src, 0));
904 case SIGN_EXTEND: /* used for NT/Alpha pointers */
906 rtx temp = find_base_value (XEXP (src, 0));
908 #ifdef POINTERS_EXTEND_UNSIGNED
909 if (temp != 0 && CONSTANT_P (temp) && GET_MODE (temp) != Pmode)
910 temp = convert_memory_address (Pmode, temp);
923 /* Called from init_alias_analysis indirectly through note_stores. */
925 /* While scanning insns to find base values, reg_seen[N] is nonzero if
926 register N has been set in this function. */
927 static char *reg_seen;
929 /* Addresses which are known not to alias anything else are identified
930 by a unique integer. */
931 static int unique_id;
934 record_set (dest, set, data)
936 void *data ATTRIBUTE_UNUSED;
942 if (GET_CODE (dest) != REG)
945 regno = REGNO (dest);
947 if (regno >= reg_base_value_size)
950 /* If this spans multiple hard registers, then we must indicate that every
951 register has an unusable value. */
952 if (regno < FIRST_PSEUDO_REGISTER)
953 n = HARD_REGNO_NREGS (regno, GET_MODE (dest));
960 reg_seen[regno + n] = 1;
961 new_reg_base_value[regno + n] = 0;
968 /* A CLOBBER wipes out any old value but does not prevent a previously
969 unset register from acquiring a base address (i.e. reg_seen is not
971 if (GET_CODE (set) == CLOBBER)
973 new_reg_base_value[regno] = 0;
982 new_reg_base_value[regno] = 0;
986 new_reg_base_value[regno] = gen_rtx_ADDRESS (Pmode,
987 GEN_INT (unique_id++));
991 /* This is not the first set. If the new value is not related to the
992 old value, forget the base value. Note that the following code is
994 extern int x, y; int *p = &x; p += (&y-&x);
995 ANSI C does not allow computing the difference of addresses
996 of distinct top level objects. */
997 if (new_reg_base_value[regno])
998 switch (GET_CODE (src))
1002 if (XEXP (src, 0) != dest && XEXP (src, 1) != dest)
1003 new_reg_base_value[regno] = 0;
1006 /* If the value we add in the PLUS is also a valid base value,
1007 this might be the actual base value, and the original value
1010 rtx other = NULL_RTX;
1012 if (XEXP (src, 0) == dest)
1013 other = XEXP (src, 1);
1014 else if (XEXP (src, 1) == dest)
1015 other = XEXP (src, 0);
1017 if (! other || find_base_value (other))
1018 new_reg_base_value[regno] = 0;
1022 if (XEXP (src, 0) != dest || GET_CODE (XEXP (src, 1)) != CONST_INT)
1023 new_reg_base_value[regno] = 0;
1026 new_reg_base_value[regno] = 0;
1029 /* If this is the first set of a register, record the value. */
1030 else if ((regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
1031 && ! reg_seen[regno] && new_reg_base_value[regno] == 0)
1032 new_reg_base_value[regno] = find_base_value (src);
1034 reg_seen[regno] = 1;
1037 /* Called from loop optimization when a new pseudo-register is
1038 created. It indicates that REGNO is being set to VAL. f INVARIANT
1039 is true then this value also describes an invariant relationship
1040 which can be used to deduce that two registers with unknown values
1044 record_base_value (regno, val, invariant)
1049 if (regno >= reg_base_value_size)
1052 if (invariant && alias_invariant)
1053 alias_invariant[regno] = val;
1055 if (GET_CODE (val) == REG)
1057 if (REGNO (val) < reg_base_value_size)
1058 reg_base_value[regno] = reg_base_value[REGNO (val)];
1063 reg_base_value[regno] = find_base_value (val);
1066 /* Clear alias info for a register. This is used if an RTL transformation
1067 changes the value of a register. This is used in flow by AUTO_INC_DEC
1068 optimizations. We don't need to clear reg_base_value, since flow only
1069 changes the offset. */
1072 clear_reg_alias_info (reg)
1075 unsigned int regno = REGNO (reg);
1077 if (regno < reg_known_value_size && regno >= FIRST_PSEUDO_REGISTER)
1078 reg_known_value[regno] = reg;
1081 /* Returns a canonical version of X, from the point of view alias
1082 analysis. (For example, if X is a MEM whose address is a register,
1083 and the register has a known value (say a SYMBOL_REF), then a MEM
1084 whose address is the SYMBOL_REF is returned.) */
1090 /* Recursively look for equivalences. */
1091 if (GET_CODE (x) == REG && REGNO (x) >= FIRST_PSEUDO_REGISTER
1092 && REGNO (x) < reg_known_value_size)
1093 return reg_known_value[REGNO (x)] == x
1094 ? x : canon_rtx (reg_known_value[REGNO (x)]);
1095 else if (GET_CODE (x) == PLUS)
1097 rtx x0 = canon_rtx (XEXP (x, 0));
1098 rtx x1 = canon_rtx (XEXP (x, 1));
1100 if (x0 != XEXP (x, 0) || x1 != XEXP (x, 1))
1102 if (GET_CODE (x0) == CONST_INT)
1103 return plus_constant (x1, INTVAL (x0));
1104 else if (GET_CODE (x1) == CONST_INT)
1105 return plus_constant (x0, INTVAL (x1));
1106 return gen_rtx_PLUS (GET_MODE (x), x0, x1);
1110 /* This gives us much better alias analysis when called from
1111 the loop optimizer. Note we want to leave the original
1112 MEM alone, but need to return the canonicalized MEM with
1113 all the flags with their original values. */
1114 else if (GET_CODE (x) == MEM)
1115 x = replace_equiv_address_nv (x, canon_rtx (XEXP (x, 0)));
1120 /* Return 1 if X and Y are identical-looking rtx's.
1122 We use the data in reg_known_value above to see if two registers with
1123 different numbers are, in fact, equivalent. */
1126 rtx_equal_for_memref_p (x, y)
1134 if (x == 0 && y == 0)
1136 if (x == 0 || y == 0)
1145 code = GET_CODE (x);
1146 /* Rtx's of different codes cannot be equal. */
1147 if (code != GET_CODE (y))
1150 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1151 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1153 if (GET_MODE (x) != GET_MODE (y))
1156 /* Some RTL can be compared without a recursive examination. */
1160 return CSELIB_VAL_PTR (x) == CSELIB_VAL_PTR (y);
1163 return REGNO (x) == REGNO (y);
1166 return XEXP (x, 0) == XEXP (y, 0);
1169 return XSTR (x, 0) == XSTR (y, 0);
1173 /* There's no need to compare the contents of CONST_DOUBLEs or
1174 CONST_INTs because pointer equality is a good enough
1175 comparison for these nodes. */
1179 return (XINT (x, 1) == XINT (y, 1)
1180 && rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0)));
1186 /* For commutative operations, the RTX match if the operand match in any
1187 order. Also handle the simple binary and unary cases without a loop. */
1188 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
1189 return ((rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0))
1190 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1)))
1191 || (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 1))
1192 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 0))));
1193 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
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 else if (GET_RTX_CLASS (code) == '1')
1197 return rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0));
1199 /* Compare the elements. If any pair of corresponding elements
1200 fail to match, return 0 for the whole things.
1202 Limit cases to types which actually appear in addresses. */
1204 fmt = GET_RTX_FORMAT (code);
1205 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1210 if (XINT (x, i) != XINT (y, i))
1215 /* Two vectors must have the same length. */
1216 if (XVECLEN (x, i) != XVECLEN (y, i))
1219 /* And the corresponding elements must match. */
1220 for (j = 0; j < XVECLEN (x, i); j++)
1221 if (rtx_equal_for_memref_p (XVECEXP (x, i, j),
1222 XVECEXP (y, i, j)) == 0)
1227 if (rtx_equal_for_memref_p (XEXP (x, i), XEXP (y, i)) == 0)
1231 /* This can happen for asm operands. */
1233 if (strcmp (XSTR (x, i), XSTR (y, i)))
1237 /* This can happen for an asm which clobbers memory. */
1241 /* It is believed that rtx's at this level will never
1242 contain anything but integers and other rtx's,
1243 except for within LABEL_REFs and SYMBOL_REFs. */
1251 /* Given an rtx X, find a SYMBOL_REF or LABEL_REF within
1252 X and return it, or return 0 if none found. */
1255 find_symbolic_term (x)
1262 code = GET_CODE (x);
1263 if (code == SYMBOL_REF || code == LABEL_REF)
1265 if (GET_RTX_CLASS (code) == 'o')
1268 fmt = GET_RTX_FORMAT (code);
1269 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1275 t = find_symbolic_term (XEXP (x, i));
1279 else if (fmt[i] == 'E')
1290 struct elt_loc_list *l;
1292 #if defined (FIND_BASE_TERM)
1293 /* Try machine-dependent ways to find the base term. */
1294 x = FIND_BASE_TERM (x);
1297 switch (GET_CODE (x))
1300 return REG_BASE_VALUE (x);
1303 if (GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (Pmode))
1313 return find_base_term (XEXP (x, 0));
1316 case SIGN_EXTEND: /* Used for Alpha/NT pointers */
1318 rtx temp = find_base_term (XEXP (x, 0));
1320 #ifdef POINTERS_EXTEND_UNSIGNED
1321 if (temp != 0 && CONSTANT_P (temp) && GET_MODE (temp) != Pmode)
1322 temp = convert_memory_address (Pmode, temp);
1329 val = CSELIB_VAL_PTR (x);
1330 for (l = val->locs; l; l = l->next)
1331 if ((x = find_base_term (l->loc)) != 0)
1337 if (GET_CODE (x) != PLUS && GET_CODE (x) != MINUS)
1344 rtx tmp1 = XEXP (x, 0);
1345 rtx tmp2 = XEXP (x, 1);
1347 /* This is a little bit tricky since we have to determine which of
1348 the two operands represents the real base address. Otherwise this
1349 routine may return the index register instead of the base register.
1351 That may cause us to believe no aliasing was possible, when in
1352 fact aliasing is possible.
1354 We use a few simple tests to guess the base register. Additional
1355 tests can certainly be added. For example, if one of the operands
1356 is a shift or multiply, then it must be the index register and the
1357 other operand is the base register. */
1359 if (tmp1 == pic_offset_table_rtx && CONSTANT_P (tmp2))
1360 return find_base_term (tmp2);
1362 /* If either operand is known to be a pointer, then use it
1363 to determine the base term. */
1364 if (REG_P (tmp1) && REG_POINTER (tmp1))
1365 return find_base_term (tmp1);
1367 if (REG_P (tmp2) && REG_POINTER (tmp2))
1368 return find_base_term (tmp2);
1370 /* Neither operand was known to be a pointer. Go ahead and find the
1371 base term for both operands. */
1372 tmp1 = find_base_term (tmp1);
1373 tmp2 = find_base_term (tmp2);
1375 /* If either base term is named object or a special address
1376 (like an argument or stack reference), then use it for the
1379 && (GET_CODE (tmp1) == SYMBOL_REF
1380 || GET_CODE (tmp1) == LABEL_REF
1381 || (GET_CODE (tmp1) == ADDRESS
1382 && GET_MODE (tmp1) != VOIDmode)))
1386 && (GET_CODE (tmp2) == SYMBOL_REF
1387 || GET_CODE (tmp2) == LABEL_REF
1388 || (GET_CODE (tmp2) == ADDRESS
1389 && GET_MODE (tmp2) != VOIDmode)))
1392 /* We could not determine which of the two operands was the
1393 base register and which was the index. So we can determine
1394 nothing from the base alias check. */
1399 if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) != 0)
1400 return find_base_term (XEXP (x, 0));
1408 return REG_BASE_VALUE (frame_pointer_rtx);
1415 /* Return 0 if the addresses X and Y are known to point to different
1416 objects, 1 if they might be pointers to the same object. */
1419 base_alias_check (x, y, x_mode, y_mode)
1421 enum machine_mode x_mode, y_mode;
1423 rtx x_base = find_base_term (x);
1424 rtx y_base = find_base_term (y);
1426 /* If the address itself has no known base see if a known equivalent
1427 value has one. If either address still has no known base, nothing
1428 is known about aliasing. */
1433 if (! flag_expensive_optimizations || (x_c = canon_rtx (x)) == x)
1436 x_base = find_base_term (x_c);
1444 if (! flag_expensive_optimizations || (y_c = canon_rtx (y)) == y)
1447 y_base = find_base_term (y_c);
1452 /* If the base addresses are equal nothing is known about aliasing. */
1453 if (rtx_equal_p (x_base, y_base))
1456 /* The base addresses of the read and write are different expressions.
1457 If they are both symbols and they are not accessed via AND, there is
1458 no conflict. We can bring knowledge of object alignment into play
1459 here. For example, on alpha, "char a, b;" can alias one another,
1460 though "char a; long b;" cannot. */
1461 if (GET_CODE (x_base) != ADDRESS && GET_CODE (y_base) != ADDRESS)
1463 if (GET_CODE (x) == AND && GET_CODE (y) == AND)
1465 if (GET_CODE (x) == AND
1466 && (GET_CODE (XEXP (x, 1)) != CONST_INT
1467 || (int) GET_MODE_UNIT_SIZE (y_mode) < -INTVAL (XEXP (x, 1))))
1469 if (GET_CODE (y) == AND
1470 && (GET_CODE (XEXP (y, 1)) != CONST_INT
1471 || (int) GET_MODE_UNIT_SIZE (x_mode) < -INTVAL (XEXP (y, 1))))
1473 /* Differing symbols never alias. */
1477 /* If one address is a stack reference there can be no alias:
1478 stack references using different base registers do not alias,
1479 a stack reference can not alias a parameter, and a stack reference
1480 can not alias a global. */
1481 if ((GET_CODE (x_base) == ADDRESS && GET_MODE (x_base) == Pmode)
1482 || (GET_CODE (y_base) == ADDRESS && GET_MODE (y_base) == Pmode))
1485 if (! flag_argument_noalias)
1488 if (flag_argument_noalias > 1)
1491 /* Weak noalias assertion (arguments are distinct, but may match globals). */
1492 return ! (GET_MODE (x_base) == VOIDmode && GET_MODE (y_base) == VOIDmode);
1495 /* Convert the address X into something we can use. This is done by returning
1496 it unchanged unless it is a value; in the latter case we call cselib to get
1497 a more useful rtx. */
1504 struct elt_loc_list *l;
1506 if (GET_CODE (x) != VALUE)
1508 v = CSELIB_VAL_PTR (x);
1509 for (l = v->locs; l; l = l->next)
1510 if (CONSTANT_P (l->loc))
1512 for (l = v->locs; l; l = l->next)
1513 if (GET_CODE (l->loc) != REG && GET_CODE (l->loc) != MEM)
1516 return v->locs->loc;
1520 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
1521 where SIZE is the size in bytes of the memory reference. If ADDR
1522 is not modified by the memory reference then ADDR is returned. */
1525 addr_side_effect_eval (addr, size, n_refs)
1532 switch (GET_CODE (addr))
1535 offset = (n_refs + 1) * size;
1538 offset = -(n_refs + 1) * size;
1541 offset = n_refs * size;
1544 offset = -n_refs * size;
1552 addr = gen_rtx_PLUS (GET_MODE (addr), XEXP (addr, 0), GEN_INT (offset));
1554 addr = XEXP (addr, 0);
1559 /* Return nonzero if X and Y (memory addresses) could reference the
1560 same location in memory. C is an offset accumulator. When
1561 C is nonzero, we are testing aliases between X and Y + C.
1562 XSIZE is the size in bytes of the X reference,
1563 similarly YSIZE is the size in bytes for Y.
1565 If XSIZE or YSIZE is zero, we do not know the amount of memory being
1566 referenced (the reference was BLKmode), so make the most pessimistic
1569 If XSIZE or YSIZE is negative, we may access memory outside the object
1570 being referenced as a side effect. This can happen when using AND to
1571 align memory references, as is done on the Alpha.
1573 Nice to notice that varying addresses cannot conflict with fp if no
1574 local variables had their addresses taken, but that's too hard now. */
1577 memrefs_conflict_p (xsize, x, ysize, y, c)
1582 if (GET_CODE (x) == VALUE)
1584 if (GET_CODE (y) == VALUE)
1586 if (GET_CODE (x) == HIGH)
1588 else if (GET_CODE (x) == LO_SUM)
1591 x = canon_rtx (addr_side_effect_eval (x, xsize, 0));
1592 if (GET_CODE (y) == HIGH)
1594 else if (GET_CODE (y) == LO_SUM)
1597 y = canon_rtx (addr_side_effect_eval (y, ysize, 0));
1599 if (rtx_equal_for_memref_p (x, y))
1601 if (xsize <= 0 || ysize <= 0)
1603 if (c >= 0 && xsize > c)
1605 if (c < 0 && ysize+c > 0)
1610 /* This code used to check for conflicts involving stack references and
1611 globals but the base address alias code now handles these cases. */
1613 if (GET_CODE (x) == PLUS)
1615 /* The fact that X is canonicalized means that this
1616 PLUS rtx is canonicalized. */
1617 rtx x0 = XEXP (x, 0);
1618 rtx x1 = XEXP (x, 1);
1620 if (GET_CODE (y) == PLUS)
1622 /* The fact that Y is canonicalized means that this
1623 PLUS rtx is canonicalized. */
1624 rtx y0 = XEXP (y, 0);
1625 rtx y1 = XEXP (y, 1);
1627 if (rtx_equal_for_memref_p (x1, y1))
1628 return memrefs_conflict_p (xsize, x0, ysize, y0, c);
1629 if (rtx_equal_for_memref_p (x0, y0))
1630 return memrefs_conflict_p (xsize, x1, ysize, y1, c);
1631 if (GET_CODE (x1) == CONST_INT)
1633 if (GET_CODE (y1) == CONST_INT)
1634 return memrefs_conflict_p (xsize, x0, ysize, y0,
1635 c - INTVAL (x1) + INTVAL (y1));
1637 return memrefs_conflict_p (xsize, x0, ysize, y,
1640 else if (GET_CODE (y1) == CONST_INT)
1641 return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
1645 else if (GET_CODE (x1) == CONST_INT)
1646 return memrefs_conflict_p (xsize, x0, ysize, y, c - INTVAL (x1));
1648 else if (GET_CODE (y) == PLUS)
1650 /* The fact that Y is canonicalized means that this
1651 PLUS rtx is canonicalized. */
1652 rtx y0 = XEXP (y, 0);
1653 rtx y1 = XEXP (y, 1);
1655 if (GET_CODE (y1) == CONST_INT)
1656 return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
1661 if (GET_CODE (x) == GET_CODE (y))
1662 switch (GET_CODE (x))
1666 /* Handle cases where we expect the second operands to be the
1667 same, and check only whether the first operand would conflict
1670 rtx x1 = canon_rtx (XEXP (x, 1));
1671 rtx y1 = canon_rtx (XEXP (y, 1));
1672 if (! rtx_equal_for_memref_p (x1, y1))
1674 x0 = canon_rtx (XEXP (x, 0));
1675 y0 = canon_rtx (XEXP (y, 0));
1676 if (rtx_equal_for_memref_p (x0, y0))
1677 return (xsize == 0 || ysize == 0
1678 || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
1680 /* Can't properly adjust our sizes. */
1681 if (GET_CODE (x1) != CONST_INT)
1683 xsize /= INTVAL (x1);
1684 ysize /= INTVAL (x1);
1686 return memrefs_conflict_p (xsize, x0, ysize, y0, c);
1690 /* Are these registers known not to be equal? */
1691 if (alias_invariant)
1693 unsigned int r_x = REGNO (x), r_y = REGNO (y);
1694 rtx i_x, i_y; /* invariant relationships of X and Y */
1696 i_x = r_x >= reg_base_value_size ? 0 : alias_invariant[r_x];
1697 i_y = r_y >= reg_base_value_size ? 0 : alias_invariant[r_y];
1699 if (i_x == 0 && i_y == 0)
1702 if (! memrefs_conflict_p (xsize, i_x ? i_x : x,
1703 ysize, i_y ? i_y : y, c))
1712 /* Treat an access through an AND (e.g. a subword access on an Alpha)
1713 as an access with indeterminate size. Assume that references
1714 besides AND are aligned, so if the size of the other reference is
1715 at least as large as the alignment, assume no other overlap. */
1716 if (GET_CODE (x) == AND && GET_CODE (XEXP (x, 1)) == CONST_INT)
1718 if (GET_CODE (y) == AND || ysize < -INTVAL (XEXP (x, 1)))
1720 return memrefs_conflict_p (xsize, XEXP (x, 0), ysize, y, c);
1722 if (GET_CODE (y) == AND && GET_CODE (XEXP (y, 1)) == CONST_INT)
1724 /* ??? If we are indexing far enough into the array/structure, we
1725 may yet be able to determine that we can not overlap. But we
1726 also need to that we are far enough from the end not to overlap
1727 a following reference, so we do nothing with that for now. */
1728 if (GET_CODE (x) == AND || xsize < -INTVAL (XEXP (y, 1)))
1730 return memrefs_conflict_p (xsize, x, ysize, XEXP (y, 0), c);
1733 if (GET_CODE (x) == ADDRESSOF)
1735 if (y == frame_pointer_rtx
1736 || GET_CODE (y) == ADDRESSOF)
1737 return xsize <= 0 || ysize <= 0;
1739 if (GET_CODE (y) == ADDRESSOF)
1741 if (x == frame_pointer_rtx)
1742 return xsize <= 0 || ysize <= 0;
1747 if (GET_CODE (x) == CONST_INT && GET_CODE (y) == CONST_INT)
1749 c += (INTVAL (y) - INTVAL (x));
1750 return (xsize <= 0 || ysize <= 0
1751 || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
1754 if (GET_CODE (x) == CONST)
1756 if (GET_CODE (y) == CONST)
1757 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
1758 ysize, canon_rtx (XEXP (y, 0)), c);
1760 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
1763 if (GET_CODE (y) == CONST)
1764 return memrefs_conflict_p (xsize, x, ysize,
1765 canon_rtx (XEXP (y, 0)), c);
1768 return (xsize <= 0 || ysize <= 0
1769 || (rtx_equal_for_memref_p (x, y)
1770 && ((c >= 0 && xsize > c) || (c < 0 && ysize+c > 0))));
1777 /* Functions to compute memory dependencies.
1779 Since we process the insns in execution order, we can build tables
1780 to keep track of what registers are fixed (and not aliased), what registers
1781 are varying in known ways, and what registers are varying in unknown
1784 If both memory references are volatile, then there must always be a
1785 dependence between the two references, since their order can not be
1786 changed. A volatile and non-volatile reference can be interchanged
1789 A MEM_IN_STRUCT reference at a non-AND varying address can never
1790 conflict with a non-MEM_IN_STRUCT reference at a fixed address. We
1791 also must allow AND addresses, because they may generate accesses
1792 outside the object being referenced. This is used to generate
1793 aligned addresses from unaligned addresses, for instance, the alpha
1794 storeqi_unaligned pattern. */
1796 /* Read dependence: X is read after read in MEM takes place. There can
1797 only be a dependence here if both reads are volatile. */
1800 read_dependence (mem, x)
1804 return MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem);
1807 /* Returns MEM1 if and only if MEM1 is a scalar at a fixed address and
1808 MEM2 is a reference to a structure at a varying address, or returns
1809 MEM2 if vice versa. Otherwise, returns NULL_RTX. If a non-NULL
1810 value is returned MEM1 and MEM2 can never alias. VARIES_P is used
1811 to decide whether or not an address may vary; it should return
1812 nonzero whenever variation is possible.
1813 MEM1_ADDR and MEM2_ADDR are the addresses of MEM1 and MEM2. */
1816 fixed_scalar_and_varying_struct_p (mem1, mem2, mem1_addr, mem2_addr, varies_p)
1818 rtx mem1_addr, mem2_addr;
1819 int (*varies_p) PARAMS ((rtx, int));
1821 if (! flag_strict_aliasing)
1824 if (MEM_SCALAR_P (mem1) && MEM_IN_STRUCT_P (mem2)
1825 && !varies_p (mem1_addr, 1) && varies_p (mem2_addr, 1))
1826 /* MEM1 is a scalar at a fixed address; MEM2 is a struct at a
1830 if (MEM_IN_STRUCT_P (mem1) && MEM_SCALAR_P (mem2)
1831 && varies_p (mem1_addr, 1) && !varies_p (mem2_addr, 1))
1832 /* MEM2 is a scalar at a fixed address; MEM1 is a struct at a
1839 /* Returns nonzero if something about the mode or address format MEM1
1840 indicates that it might well alias *anything*. */
1843 aliases_everything_p (mem)
1846 if (GET_CODE (XEXP (mem, 0)) == AND)
1847 /* If the address is an AND, its very hard to know at what it is
1848 actually pointing. */
1854 /* Return true if we can determine that the fields referenced cannot
1855 overlap for any pair of objects. */
1858 nonoverlapping_component_refs_p (x, y)
1861 tree fieldx, fieldy, typex, typey, orig_y;
1865 /* The comparison has to be done at a common type, since we don't
1866 know how the inheritance hierarchy works. */
1870 fieldx = TREE_OPERAND (x, 1);
1871 typex = DECL_FIELD_CONTEXT (fieldx);
1876 fieldy = TREE_OPERAND (y, 1);
1877 typey = DECL_FIELD_CONTEXT (fieldy);
1882 y = TREE_OPERAND (y, 0);
1884 while (y && TREE_CODE (y) == COMPONENT_REF);
1886 x = TREE_OPERAND (x, 0);
1888 while (x && TREE_CODE (x) == COMPONENT_REF);
1890 /* Never found a common type. */
1894 /* If we're left with accessing different fields of a structure,
1896 if (TREE_CODE (typex) == RECORD_TYPE
1897 && fieldx != fieldy)
1900 /* The comparison on the current field failed. If we're accessing
1901 a very nested structure, look at the next outer level. */
1902 x = TREE_OPERAND (x, 0);
1903 y = TREE_OPERAND (y, 0);
1906 && TREE_CODE (x) == COMPONENT_REF
1907 && TREE_CODE (y) == COMPONENT_REF);
1912 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
1915 decl_for_component_ref (x)
1920 x = TREE_OPERAND (x, 0);
1922 while (x && TREE_CODE (x) == COMPONENT_REF);
1924 return x && DECL_P (x) ? x : NULL_TREE;
1927 /* Walk up the COMPONENT_REF list and adjust OFFSET to compensate for the
1928 offset of the field reference. */
1931 adjust_offset_for_component_ref (x, offset)
1935 HOST_WIDE_INT ioffset;
1940 ioffset = INTVAL (offset);
1943 tree field = TREE_OPERAND (x, 1);
1945 if (! host_integerp (DECL_FIELD_OFFSET (field), 1))
1947 ioffset += (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1948 + (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1951 x = TREE_OPERAND (x, 0);
1953 while (x && TREE_CODE (x) == COMPONENT_REF);
1955 return GEN_INT (ioffset);
1958 /* Return nonzero if we can determine the exprs corresponding to memrefs
1959 X and Y and they do not overlap. */
1962 nonoverlapping_memrefs_p (x, y)
1965 tree exprx = MEM_EXPR (x), expry = MEM_EXPR (y);
1968 rtx moffsetx, moffsety;
1969 HOST_WIDE_INT offsetx = 0, offsety = 0, sizex, sizey, tem;
1971 /* Unless both have exprs, we can't tell anything. */
1972 if (exprx == 0 || expry == 0)
1975 /* If both are field references, we may be able to determine something. */
1976 if (TREE_CODE (exprx) == COMPONENT_REF
1977 && TREE_CODE (expry) == COMPONENT_REF
1978 && nonoverlapping_component_refs_p (exprx, expry))
1981 /* If the field reference test failed, look at the DECLs involved. */
1982 moffsetx = MEM_OFFSET (x);
1983 if (TREE_CODE (exprx) == COMPONENT_REF)
1985 tree t = decl_for_component_ref (exprx);
1988 moffsetx = adjust_offset_for_component_ref (exprx, moffsetx);
1991 else if (TREE_CODE (exprx) == INDIRECT_REF)
1993 exprx = TREE_OPERAND (exprx, 0);
1994 if (flag_argument_noalias < 2
1995 || TREE_CODE (exprx) != PARM_DECL)
1999 moffsety = MEM_OFFSET (y);
2000 if (TREE_CODE (expry) == COMPONENT_REF)
2002 tree t = decl_for_component_ref (expry);
2005 moffsety = adjust_offset_for_component_ref (expry, moffsety);
2008 else if (TREE_CODE (expry) == INDIRECT_REF)
2010 expry = TREE_OPERAND (expry, 0);
2011 if (flag_argument_noalias < 2
2012 || TREE_CODE (expry) != PARM_DECL)
2016 if (! DECL_P (exprx) || ! DECL_P (expry))
2019 rtlx = DECL_RTL (exprx);
2020 rtly = DECL_RTL (expry);
2022 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
2023 can't overlap unless they are the same because we never reuse that part
2024 of the stack frame used for locals for spilled pseudos. */
2025 if ((GET_CODE (rtlx) != MEM || GET_CODE (rtly) != MEM)
2026 && ! rtx_equal_p (rtlx, rtly))
2029 /* Get the base and offsets of both decls. If either is a register, we
2030 know both are and are the same, so use that as the base. The only
2031 we can avoid overlap is if we can deduce that they are nonoverlapping
2032 pieces of that decl, which is very rare. */
2033 basex = GET_CODE (rtlx) == MEM ? XEXP (rtlx, 0) : rtlx;
2034 if (GET_CODE (basex) == PLUS && GET_CODE (XEXP (basex, 1)) == CONST_INT)
2035 offsetx = INTVAL (XEXP (basex, 1)), basex = XEXP (basex, 0);
2037 basey = GET_CODE (rtly) == MEM ? XEXP (rtly, 0) : rtly;
2038 if (GET_CODE (basey) == PLUS && GET_CODE (XEXP (basey, 1)) == CONST_INT)
2039 offsety = INTVAL (XEXP (basey, 1)), basey = XEXP (basey, 0);
2041 /* If the bases are different, we know they do not overlap if both
2042 are constants or if one is a constant and the other a pointer into the
2043 stack frame. Otherwise a different base means we can't tell if they
2045 if (! rtx_equal_p (basex, basey))
2046 return ((CONSTANT_P (basex) && CONSTANT_P (basey))
2047 || (CONSTANT_P (basex) && REG_P (basey)
2048 && REGNO_PTR_FRAME_P (REGNO (basey)))
2049 || (CONSTANT_P (basey) && REG_P (basex)
2050 && REGNO_PTR_FRAME_P (REGNO (basex))));
2052 sizex = (GET_CODE (rtlx) != MEM ? (int) GET_MODE_SIZE (GET_MODE (rtlx))
2053 : MEM_SIZE (rtlx) ? INTVAL (MEM_SIZE (rtlx))
2055 sizey = (GET_CODE (rtly) != MEM ? (int) GET_MODE_SIZE (GET_MODE (rtly))
2056 : MEM_SIZE (rtly) ? INTVAL (MEM_SIZE (rtly)) :
2059 /* If we have an offset for either memref, it can update the values computed
2062 offsetx += INTVAL (moffsetx), sizex -= INTVAL (moffsetx);
2064 offsety += INTVAL (moffsety), sizey -= INTVAL (moffsety);
2066 /* If a memref has both a size and an offset, we can use the smaller size.
2067 We can't do this if the offset isn't known because we must view this
2068 memref as being anywhere inside the DECL's MEM. */
2069 if (MEM_SIZE (x) && moffsetx)
2070 sizex = INTVAL (MEM_SIZE (x));
2071 if (MEM_SIZE (y) && moffsety)
2072 sizey = INTVAL (MEM_SIZE (y));
2074 /* Put the values of the memref with the lower offset in X's values. */
2075 if (offsetx > offsety)
2077 tem = offsetx, offsetx = offsety, offsety = tem;
2078 tem = sizex, sizex = sizey, sizey = tem;
2081 /* If we don't know the size of the lower-offset value, we can't tell
2082 if they conflict. Otherwise, we do the test. */
2083 return sizex >= 0 && offsety >= offsetx + sizex;
2086 /* True dependence: X is read after store in MEM takes place. */
2089 true_dependence (mem, mem_mode, x, varies)
2091 enum machine_mode mem_mode;
2093 int (*varies) PARAMS ((rtx, int));
2095 rtx x_addr, mem_addr;
2098 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2101 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2102 This is used in epilogue deallocation functions. */
2103 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
2105 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
2108 if (DIFFERENT_ALIAS_SETS_P (x, mem))
2111 /* Unchanging memory can't conflict with non-unchanging memory.
2112 A non-unchanging read can conflict with a non-unchanging write.
2113 An unchanging read can conflict with an unchanging write since
2114 there may be a single store to this address to initialize it.
2115 Note that an unchanging store can conflict with a non-unchanging read
2116 since we have to make conservative assumptions when we have a
2117 record with readonly fields and we are copying the whole thing.
2118 Just fall through to the code below to resolve potential conflicts.
2119 This won't handle all cases optimally, but the possible performance
2120 loss should be negligible. */
2121 if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem))
2124 if (nonoverlapping_memrefs_p (mem, x))
2127 if (mem_mode == VOIDmode)
2128 mem_mode = GET_MODE (mem);
2130 x_addr = get_addr (XEXP (x, 0));
2131 mem_addr = get_addr (XEXP (mem, 0));
2133 base = find_base_term (x_addr);
2134 if (base && (GET_CODE (base) == LABEL_REF
2135 || (GET_CODE (base) == SYMBOL_REF
2136 && CONSTANT_POOL_ADDRESS_P (base))))
2139 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode))
2142 x_addr = canon_rtx (x_addr);
2143 mem_addr = canon_rtx (mem_addr);
2145 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
2146 SIZE_FOR_MODE (x), x_addr, 0))
2149 if (aliases_everything_p (x))
2152 /* We cannot use aliases_everything_p to test MEM, since we must look
2153 at MEM_MODE, rather than GET_MODE (MEM). */
2154 if (mem_mode == QImode || GET_CODE (mem_addr) == AND)
2157 /* In true_dependence we also allow BLKmode to alias anything. Why
2158 don't we do this in anti_dependence and output_dependence? */
2159 if (mem_mode == BLKmode || GET_MODE (x) == BLKmode)
2162 return ! fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr,
2166 /* Canonical true dependence: X is read after store in MEM takes place.
2167 Variant of true_dependence which assumes MEM has already been
2168 canonicalized (hence we no longer do that here).
2169 The mem_addr argument has been added, since true_dependence computed
2170 this value prior to canonicalizing. */
2173 canon_true_dependence (mem, mem_mode, mem_addr, x, varies)
2174 rtx mem, mem_addr, x;
2175 enum machine_mode mem_mode;
2176 int (*varies) PARAMS ((rtx, int));
2180 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2183 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2184 This is used in epilogue deallocation functions. */
2185 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
2187 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
2190 if (DIFFERENT_ALIAS_SETS_P (x, mem))
2193 /* If X is an unchanging read, then it can't possibly conflict with any
2194 non-unchanging store. It may conflict with an unchanging write though,
2195 because there may be a single store to this address to initialize it.
2196 Just fall through to the code below to resolve the case where we have
2197 both an unchanging read and an unchanging write. This won't handle all
2198 cases optimally, but the possible performance loss should be
2200 if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem))
2203 if (nonoverlapping_memrefs_p (x, mem))
2206 x_addr = get_addr (XEXP (x, 0));
2208 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode))
2211 x_addr = canon_rtx (x_addr);
2212 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
2213 SIZE_FOR_MODE (x), x_addr, 0))
2216 if (aliases_everything_p (x))
2219 /* We cannot use aliases_everything_p to test MEM, since we must look
2220 at MEM_MODE, rather than GET_MODE (MEM). */
2221 if (mem_mode == QImode || GET_CODE (mem_addr) == AND)
2224 /* In true_dependence we also allow BLKmode to alias anything. Why
2225 don't we do this in anti_dependence and output_dependence? */
2226 if (mem_mode == BLKmode || GET_MODE (x) == BLKmode)
2229 return ! fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr,
2233 /* Returns nonzero if a write to X might alias a previous read from
2234 (or, if WRITEP is nonzero, a write to) MEM. */
2237 write_dependence_p (mem, x, writep)
2242 rtx x_addr, mem_addr;
2246 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2249 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2250 This is used in epilogue deallocation functions. */
2251 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
2253 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
2256 if (DIFFERENT_ALIAS_SETS_P (x, mem))
2259 /* Unchanging memory can't conflict with non-unchanging memory. */
2260 if (RTX_UNCHANGING_P (x) != RTX_UNCHANGING_P (mem))
2263 /* If MEM is an unchanging read, then it can't possibly conflict with
2264 the store to X, because there is at most one store to MEM, and it must
2265 have occurred somewhere before MEM. */
2266 if (! writep && RTX_UNCHANGING_P (mem))
2269 if (nonoverlapping_memrefs_p (x, mem))
2272 x_addr = get_addr (XEXP (x, 0));
2273 mem_addr = get_addr (XEXP (mem, 0));
2277 base = find_base_term (mem_addr);
2278 if (base && (GET_CODE (base) == LABEL_REF
2279 || (GET_CODE (base) == SYMBOL_REF
2280 && CONSTANT_POOL_ADDRESS_P (base))))
2284 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x),
2288 x_addr = canon_rtx (x_addr);
2289 mem_addr = canon_rtx (mem_addr);
2291 if (!memrefs_conflict_p (SIZE_FOR_MODE (mem), mem_addr,
2292 SIZE_FOR_MODE (x), x_addr, 0))
2296 = fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr,
2299 return (!(fixed_scalar == mem && !aliases_everything_p (x))
2300 && !(fixed_scalar == x && !aliases_everything_p (mem)));
2303 /* Anti dependence: X is written after read in MEM takes place. */
2306 anti_dependence (mem, x)
2310 return write_dependence_p (mem, x, /*writep=*/0);
2313 /* Output dependence: X is written after store in MEM takes place. */
2316 output_dependence (mem, x)
2320 return write_dependence_p (mem, x, /*writep=*/1);
2323 /* A subroutine of nonlocal_mentioned_p, returns 1 if *LOC mentions
2324 something which is not local to the function and is not constant. */
2327 nonlocal_mentioned_p_1 (loc, data)
2329 void *data ATTRIBUTE_UNUSED;
2338 switch (GET_CODE (x))
2341 if (GET_CODE (SUBREG_REG (x)) == REG)
2343 /* Global registers are not local. */
2344 if (REGNO (SUBREG_REG (x)) < FIRST_PSEUDO_REGISTER
2345 && global_regs[subreg_regno (x)])
2353 /* Global registers are not local. */
2354 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2369 /* Constants in the function's constants pool are constant. */
2370 if (CONSTANT_POOL_ADDRESS_P (x))
2375 /* Non-constant calls and recursion are not local. */
2379 /* Be overly conservative and consider any volatile memory
2380 reference as not local. */
2381 if (MEM_VOLATILE_P (x))
2383 base = find_base_term (XEXP (x, 0));
2386 /* A Pmode ADDRESS could be a reference via the structure value
2387 address or static chain. Such memory references are nonlocal.
2389 Thus, we have to examine the contents of the ADDRESS to find
2390 out if this is a local reference or not. */
2391 if (GET_CODE (base) == ADDRESS
2392 && GET_MODE (base) == Pmode
2393 && (XEXP (base, 0) == stack_pointer_rtx
2394 || XEXP (base, 0) == arg_pointer_rtx
2395 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2396 || XEXP (base, 0) == hard_frame_pointer_rtx
2398 || XEXP (base, 0) == frame_pointer_rtx))
2400 /* Constants in the function's constant pool are constant. */
2401 if (GET_CODE (base) == SYMBOL_REF && CONSTANT_POOL_ADDRESS_P (base))
2406 case UNSPEC_VOLATILE:
2411 if (MEM_VOLATILE_P (x))
2423 /* Returns nonzero if X might mention something which is not
2424 local to the function and is not constant. */
2427 nonlocal_mentioned_p (x)
2433 if (GET_CODE (x) == CALL_INSN)
2435 if (! CONST_OR_PURE_CALL_P (x))
2437 x = CALL_INSN_FUNCTION_USAGE (x);
2445 return for_each_rtx (&x, nonlocal_mentioned_p_1, NULL);
2448 /* A subroutine of nonlocal_referenced_p, returns 1 if *LOC references
2449 something which is not local to the function and is not constant. */
2452 nonlocal_referenced_p_1 (loc, data)
2454 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 (GET_CODE (SET_DEST (x)) == MEM)
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 && GET_CODE (SET_DEST (x)) != REG
2487 && ! (GET_CODE (SET_DEST (x)) == SUBREG
2488 && GET_CODE (SUBREG_REG (SET_DEST (x))) == REG
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 (GET_CODE (XEXP (x, 0)) == MEM)
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 (x)
2531 if (GET_CODE (x) == CALL_INSN)
2533 if (! CONST_OR_PURE_CALL_P (x))
2535 x = CALL_INSN_FUNCTION_USAGE (x);
2543 return for_each_rtx (&x, nonlocal_referenced_p_1, NULL);
2546 /* A subroutine of nonlocal_set_p, returns 1 if *LOC sets
2547 something which is not local to the function and is not constant. */
2550 nonlocal_set_p_1 (loc, data)
2552 void *data ATTRIBUTE_UNUSED;
2559 switch (GET_CODE (x))
2562 /* Non-constant calls and recursion are not local. */
2571 return nonlocal_mentioned_p (XEXP (x, 0));
2574 if (nonlocal_mentioned_p (SET_DEST (x)))
2576 return nonlocal_set_p (SET_SRC (x));
2579 return nonlocal_mentioned_p (XEXP (x, 0));
2585 case UNSPEC_VOLATILE:
2589 if (MEM_VOLATILE_P (x))
2601 /* Returns nonzero if X might set something which is not
2602 local to the function and is not constant. */
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 constant. */
2629 mark_constant_function ()
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 || TYPE_MODE (TREE_TYPE (current_function_decl)) == VOIDmode
2638 || current_function_has_nonlocal_goto
2639 || !(*targetm.binds_local_p) (current_function_decl))
2642 /* A loop might not return which counts as a side effect. */
2643 if (mark_dfs_back_edges ())
2646 nonlocal_memory_referenced = 0;
2648 init_alias_analysis ();
2650 /* Determine if this is a constant or pure function. */
2652 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2654 if (! INSN_P (insn))
2657 if (nonlocal_set_p (insn) || global_reg_mentioned_p (insn)
2658 || volatile_refs_p (PATTERN (insn)))
2661 if (! nonlocal_memory_referenced)
2662 nonlocal_memory_referenced = nonlocal_referenced_p (insn);
2665 end_alias_analysis ();
2667 /* Mark the function. */
2671 else if (nonlocal_memory_referenced)
2672 cgraph_rtl_info (current_function_decl)->pure_function = 1;
2674 cgraph_rtl_info (current_function_decl)->const_function = 1;
2683 #ifndef OUTGOING_REGNO
2684 #define OUTGOING_REGNO(N) N
2686 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2687 /* Check whether this register can hold an incoming pointer
2688 argument. FUNCTION_ARG_REGNO_P tests outgoing register
2689 numbers, so translate if necessary due to register windows. */
2690 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i))
2691 && HARD_REGNO_MODE_OK (i, Pmode))
2692 static_reg_base_value[i]
2693 = gen_rtx_ADDRESS (VOIDmode, gen_rtx_REG (Pmode, i));
2695 static_reg_base_value[STACK_POINTER_REGNUM]
2696 = gen_rtx_ADDRESS (Pmode, stack_pointer_rtx);
2697 static_reg_base_value[ARG_POINTER_REGNUM]
2698 = gen_rtx_ADDRESS (Pmode, arg_pointer_rtx);
2699 static_reg_base_value[FRAME_POINTER_REGNUM]
2700 = gen_rtx_ADDRESS (Pmode, frame_pointer_rtx);
2701 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2702 static_reg_base_value[HARD_FRAME_POINTER_REGNUM]
2703 = gen_rtx_ADDRESS (Pmode, hard_frame_pointer_rtx);
2706 alias_sets = splay_tree_new (splay_tree_compare_ints, 0, 0);
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 (x, pat, data)
2714 rtx x, pat ATTRIBUTE_UNUSED;
2717 if (GET_CODE (x) == MEM)
2719 if (anti_dependence (x, (rtx)data) || output_dependence (x, (rtx)data))
2720 memory_modified = true;
2725 /* Return true when INSN possibly modify memory contents of MEM
2726 (ie address can be modified). */
2728 memory_modified_in_insn_p (mem, insn)
2733 memory_modified = false;
2734 note_stores (PATTERN (insn), memory_modified_1, mem);
2735 return memory_modified;
2738 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
2742 init_alias_analysis ()
2744 int maxreg = max_reg_num ();
2750 timevar_push (TV_ALIAS_ANALYSIS);
2752 reg_known_value_size = maxreg;
2755 = (rtx *) xcalloc ((maxreg - FIRST_PSEUDO_REGISTER), sizeof (rtx))
2756 - FIRST_PSEUDO_REGISTER;
2758 = (char*) xcalloc ((maxreg - FIRST_PSEUDO_REGISTER), sizeof (char))
2759 - FIRST_PSEUDO_REGISTER;
2761 /* Overallocate reg_base_value to allow some growth during loop
2762 optimization. Loop unrolling can create a large number of
2764 reg_base_value_size = maxreg * 2;
2765 reg_base_value = (rtx *) ggc_alloc_cleared (reg_base_value_size
2768 new_reg_base_value = (rtx *) xmalloc (reg_base_value_size * sizeof (rtx));
2769 reg_seen = (char *) xmalloc (reg_base_value_size);
2770 if (! reload_completed && flag_old_unroll_loops)
2772 /* ??? Why are we realloc'ing if we're just going to zero it? */
2773 alias_invariant = (rtx *)xrealloc (alias_invariant,
2774 reg_base_value_size * sizeof (rtx));
2775 memset ((char *)alias_invariant, 0, reg_base_value_size * sizeof (rtx));
2778 /* The basic idea is that each pass through this loop will use the
2779 "constant" information from the previous pass to propagate alias
2780 information through another level of assignments.
2782 This could get expensive if the assignment chains are long. Maybe
2783 we should throttle the number of iterations, possibly based on
2784 the optimization level or flag_expensive_optimizations.
2786 We could propagate more information in the first pass by making use
2787 of REG_N_SETS to determine immediately that the alias information
2788 for a pseudo is "constant".
2790 A program with an uninitialized variable can cause an infinite loop
2791 here. Instead of doing a full dataflow analysis to detect such problems
2792 we just cap the number of iterations for the loop.
2794 The state of the arrays for the set chain in question does not matter
2795 since the program has undefined behavior. */
2800 /* Assume nothing will change this iteration of the loop. */
2803 /* We want to assign the same IDs each iteration of this loop, so
2804 start counting from zero each iteration of the loop. */
2807 /* We're at the start of the function each iteration through the
2808 loop, so we're copying arguments. */
2809 copying_arguments = true;
2811 /* Wipe the potential alias information clean for this pass. */
2812 memset ((char *) new_reg_base_value, 0, reg_base_value_size * sizeof (rtx));
2814 /* Wipe the reg_seen array clean. */
2815 memset ((char *) reg_seen, 0, reg_base_value_size);
2817 /* Mark all hard registers which may contain an address.
2818 The stack, frame and argument pointers may contain an address.
2819 An argument register which can hold a Pmode value may contain
2820 an address even if it is not in BASE_REGS.
2822 The address expression is VOIDmode for an argument and
2823 Pmode for other registers. */
2825 memcpy (new_reg_base_value, static_reg_base_value,
2826 FIRST_PSEUDO_REGISTER * sizeof (rtx));
2828 /* Walk the insns adding values to the new_reg_base_value array. */
2829 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2835 #if defined (HAVE_prologue) || defined (HAVE_epilogue)
2836 /* The prologue/epilogue insns are not threaded onto the
2837 insn chain until after reload has completed. Thus,
2838 there is no sense wasting time checking if INSN is in
2839 the prologue/epilogue until after reload has completed. */
2840 if (reload_completed
2841 && prologue_epilogue_contains (insn))
2845 /* If this insn has a noalias note, process it, Otherwise,
2846 scan for sets. A simple set will have no side effects
2847 which could change the base value of any other register. */
2849 if (GET_CODE (PATTERN (insn)) == SET
2850 && REG_NOTES (insn) != 0
2851 && find_reg_note (insn, REG_NOALIAS, NULL_RTX))
2852 record_set (SET_DEST (PATTERN (insn)), NULL_RTX, NULL);
2854 note_stores (PATTERN (insn), record_set, NULL);
2856 set = single_set (insn);
2859 && GET_CODE (SET_DEST (set)) == REG
2860 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER)
2862 unsigned int regno = REGNO (SET_DEST (set));
2863 rtx src = SET_SRC (set);
2865 if (REG_NOTES (insn) != 0
2866 && (((note = find_reg_note (insn, REG_EQUAL, 0)) != 0
2867 && REG_N_SETS (regno) == 1)
2868 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) != 0)
2869 && GET_CODE (XEXP (note, 0)) != EXPR_LIST
2870 && ! rtx_varies_p (XEXP (note, 0), 1)
2871 && ! reg_overlap_mentioned_p (SET_DEST (set), XEXP (note, 0)))
2873 reg_known_value[regno] = XEXP (note, 0);
2874 reg_known_equiv_p[regno] = REG_NOTE_KIND (note) == REG_EQUIV;
2876 else if (REG_N_SETS (regno) == 1
2877 && GET_CODE (src) == PLUS
2878 && GET_CODE (XEXP (src, 0)) == REG
2879 && REGNO (XEXP (src, 0)) >= FIRST_PSEUDO_REGISTER
2880 && (reg_known_value[REGNO (XEXP (src, 0))])
2881 && GET_CODE (XEXP (src, 1)) == CONST_INT)
2883 rtx op0 = XEXP (src, 0);
2884 op0 = reg_known_value[REGNO (op0)];
2885 reg_known_value[regno]
2886 = plus_constant (op0, INTVAL (XEXP (src, 1)));
2887 reg_known_equiv_p[regno] = 0;
2889 else if (REG_N_SETS (regno) == 1
2890 && ! rtx_varies_p (src, 1))
2892 reg_known_value[regno] = src;
2893 reg_known_equiv_p[regno] = 0;
2897 else if (GET_CODE (insn) == NOTE
2898 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_BEG)
2899 copying_arguments = false;
2902 /* Now propagate values from new_reg_base_value to reg_base_value. */
2903 for (ui = 0; ui < reg_base_value_size; ui++)
2905 if (new_reg_base_value[ui]
2906 && new_reg_base_value[ui] != reg_base_value[ui]
2907 && ! rtx_equal_p (new_reg_base_value[ui], reg_base_value[ui]))
2909 reg_base_value[ui] = new_reg_base_value[ui];
2914 while (changed && ++pass < MAX_ALIAS_LOOP_PASSES);
2916 /* Fill in the remaining entries. */
2917 for (i = FIRST_PSEUDO_REGISTER; i < maxreg; i++)
2918 if (reg_known_value[i] == 0)
2919 reg_known_value[i] = regno_reg_rtx[i];
2921 /* Simplify the reg_base_value array so that no register refers to
2922 another register, except to special registers indirectly through
2923 ADDRESS expressions.
2925 In theory this loop can take as long as O(registers^2), but unless
2926 there are very long dependency chains it will run in close to linear
2929 This loop may not be needed any longer now that the main loop does
2930 a better job at propagating alias information. */
2936 for (ui = 0; ui < reg_base_value_size; ui++)
2938 rtx base = reg_base_value[ui];
2939 if (base && GET_CODE (base) == REG)
2941 unsigned int base_regno = REGNO (base);
2942 if (base_regno == ui) /* register set from itself */
2943 reg_base_value[ui] = 0;
2945 reg_base_value[ui] = reg_base_value[base_regno];
2950 while (changed && pass < MAX_ALIAS_LOOP_PASSES);
2953 free (new_reg_base_value);
2954 new_reg_base_value = 0;
2957 timevar_pop (TV_ALIAS_ANALYSIS);
2961 end_alias_analysis ()
2963 free (reg_known_value + FIRST_PSEUDO_REGISTER);
2964 reg_known_value = 0;
2965 reg_known_value_size = 0;
2966 free (reg_known_equiv_p + FIRST_PSEUDO_REGISTER);
2967 reg_known_equiv_p = 0;
2969 reg_base_value_size = 0;
2970 if (alias_invariant)
2972 free (alias_invariant);
2973 alias_invariant = 0;
2977 #include "gt-alias.h"