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"
45 /* The alias sets assigned to MEMs assist the back-end in determining
46 which MEMs can alias which other MEMs. In general, two MEMs in
47 different alias sets cannot alias each other, with one important
48 exception. Consider something like:
50 struct S {int i; double d; };
52 a store to an `S' can alias something of either type `int' or type
53 `double'. (However, a store to an `int' cannot alias a `double'
54 and vice versa.) We indicate this via a tree structure that looks
62 (The arrows are directed and point downwards.)
63 In this situation we say the alias set for `struct S' is the
64 `superset' and that those for `int' and `double' are `subsets'.
66 To see whether two alias sets can point to the same memory, we must
67 see if either alias set is a subset of the other. We need not trace
68 past immediate descendants, however, since we propagate all
69 grandchildren up one level.
71 Alias set zero is implicitly a superset of all other alias sets.
72 However, this is no actual entry for alias set zero. It is an
73 error to attempt to explicitly construct a subset of zero. */
75 typedef struct alias_set_entry
77 /* The alias set number, as stored in MEM_ALIAS_SET. */
78 HOST_WIDE_INT alias_set;
80 /* The children of the alias set. These are not just the immediate
81 children, but, in fact, all descendants. So, if we have:
83 struct T { struct S s; float f; }
85 continuing our example above, the children here will be all of
86 `int', `double', `float', and `struct S'. */
89 /* Nonzero if would have a child of zero: this effectively makes this
90 alias set the same as alias set zero. */
94 static int rtx_equal_for_memref_p PARAMS ((rtx, rtx));
95 static rtx find_symbolic_term PARAMS ((rtx));
96 rtx get_addr PARAMS ((rtx));
97 static int memrefs_conflict_p PARAMS ((int, rtx, int, rtx,
99 static void record_set PARAMS ((rtx, rtx, void *));
100 static rtx find_base_term PARAMS ((rtx));
101 static int base_alias_check PARAMS ((rtx, rtx, enum machine_mode,
103 static rtx find_base_value PARAMS ((rtx));
104 static int mems_in_disjoint_alias_sets_p PARAMS ((rtx, rtx));
105 static int insert_subset_children PARAMS ((splay_tree_node, void*));
106 static tree find_base_decl PARAMS ((tree));
107 static alias_set_entry get_alias_set_entry PARAMS ((HOST_WIDE_INT));
108 static rtx fixed_scalar_and_varying_struct_p PARAMS ((rtx, rtx, rtx, rtx,
109 int (*) (rtx, int)));
110 static int aliases_everything_p PARAMS ((rtx));
111 static bool nonoverlapping_component_refs_p PARAMS ((tree, tree));
112 static tree decl_for_component_ref PARAMS ((tree));
113 static rtx adjust_offset_for_component_ref PARAMS ((tree, rtx));
114 static int nonoverlapping_memrefs_p PARAMS ((rtx, rtx));
115 static int write_dependence_p PARAMS ((rtx, rtx, int));
117 static int nonlocal_mentioned_p_1 PARAMS ((rtx *, void *));
118 static int nonlocal_mentioned_p PARAMS ((rtx));
119 static int nonlocal_referenced_p_1 PARAMS ((rtx *, void *));
120 static int nonlocal_referenced_p PARAMS ((rtx));
121 static int nonlocal_set_p_1 PARAMS ((rtx *, void *));
122 static int nonlocal_set_p PARAMS ((rtx));
123 static void memory_modified_1 PARAMS ((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((length ("reg_base_value_size"))) rtx *reg_base_value;
161 static rtx *new_reg_base_value;
162 static unsigned int reg_base_value_size; /* size of reg_base_value array */
164 /* Static hunks of RTL used by the aliasing code; these are initialized
165 once per function to avoid unnecessary RTL allocations. */
166 static GTY (()) rtx static_reg_base_value[FIRST_PSEUDO_REGISTER];
168 #define REG_BASE_VALUE(X) \
169 (REGNO (X) < reg_base_value_size \
170 ? reg_base_value[REGNO (X)] : 0)
172 /* Vector of known invariant relationships between registers. Set in
173 loop unrolling. Indexed by register number, if nonzero the value
174 is an expression describing this register in terms of another.
176 The length of this array is REG_BASE_VALUE_SIZE.
178 Because this array contains only pseudo registers it has no effect
180 static rtx *alias_invariant;
182 /* Vector indexed by N giving the initial (unchanging) value known for
183 pseudo-register N. This array is initialized in
184 init_alias_analysis, and does not change until end_alias_analysis
186 rtx *reg_known_value;
188 /* Indicates number of valid entries in reg_known_value. */
189 static unsigned int reg_known_value_size;
191 /* Vector recording for each reg_known_value whether it is due to a
192 REG_EQUIV note. Future passes (viz., reload) may replace the
193 pseudo with the equivalent expression and so we account for the
194 dependences that would be introduced if that happens.
196 The REG_EQUIV notes created in assign_parms may mention the arg
197 pointer, and there are explicit insns in the RTL that modify the
198 arg pointer. Thus we must ensure that such insns don't get
199 scheduled across each other because that would invalidate the
200 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
201 wrong, but solving the problem in the scheduler will likely give
202 better code, so we do it here. */
203 char *reg_known_equiv_p;
205 /* True when scanning insns from the start of the rtl to the
206 NOTE_INSN_FUNCTION_BEG note. */
207 static bool copying_arguments;
209 /* The splay-tree used to store the various alias set entries. */
210 static splay_tree alias_sets;
212 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
213 such an entry, or NULL otherwise. */
215 static alias_set_entry
216 get_alias_set_entry (alias_set)
217 HOST_WIDE_INT alias_set;
220 = splay_tree_lookup (alias_sets, (splay_tree_key) alias_set);
222 return sn != 0 ? ((alias_set_entry) sn->value) : 0;
225 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
226 the two MEMs cannot alias each other. */
229 mems_in_disjoint_alias_sets_p (mem1, mem2)
233 #ifdef ENABLE_CHECKING
234 /* Perform a basic sanity check. Namely, that there are no alias sets
235 if we're not using strict aliasing. This helps to catch bugs
236 whereby someone uses PUT_CODE, but doesn't clear MEM_ALIAS_SET, or
237 where a MEM is allocated in some way other than by the use of
238 gen_rtx_MEM, and the MEM_ALIAS_SET is not cleared. If we begin to
239 use alias sets to indicate that spilled registers cannot alias each
240 other, we might need to remove this check. */
241 if (! flag_strict_aliasing
242 && (MEM_ALIAS_SET (mem1) != 0 || MEM_ALIAS_SET (mem2) != 0))
246 return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1), MEM_ALIAS_SET (mem2));
249 /* Insert the NODE into the splay tree given by DATA. Used by
250 record_alias_subset via splay_tree_foreach. */
253 insert_subset_children (node, data)
254 splay_tree_node node;
257 splay_tree_insert ((splay_tree) data, node->key, node->value);
262 /* Return 1 if the two specified alias sets may conflict. */
265 alias_sets_conflict_p (set1, set2)
266 HOST_WIDE_INT set1, set2;
270 /* If have no alias set information for one of the operands, we have
271 to assume it can alias anything. */
272 if (set1 == 0 || set2 == 0
273 /* If the two alias sets are the same, they may alias. */
277 /* See if the first alias set is a subset of the second. */
278 ase = get_alias_set_entry (set1);
280 && (ase->has_zero_child
281 || splay_tree_lookup (ase->children,
282 (splay_tree_key) set2)))
285 /* Now do the same, but with the alias sets reversed. */
286 ase = get_alias_set_entry (set2);
288 && (ase->has_zero_child
289 || splay_tree_lookup (ase->children,
290 (splay_tree_key) set1)))
293 /* The two alias sets are distinct and neither one is the
294 child of the other. Therefore, they cannot alias. */
298 /* Return 1 if TYPE is a RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE and has
299 has any readonly fields. If any of the fields have types that
300 contain readonly fields, return true as well. */
303 readonly_fields_p (type)
308 if (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
309 && TREE_CODE (type) != QUAL_UNION_TYPE)
312 for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field))
313 if (TREE_CODE (field) == FIELD_DECL
314 && (TREE_READONLY (field)
315 || readonly_fields_p (TREE_TYPE (field))))
321 /* Return 1 if any MEM object of type T1 will always conflict (using the
322 dependency routines in this file) with any MEM object of type T2.
323 This is used when allocating temporary storage. If T1 and/or T2 are
324 NULL_TREE, it means we know nothing about the storage. */
327 objects_must_conflict_p (t1, t2)
330 /* If neither has a type specified, we don't know if they'll conflict
331 because we may be using them to store objects of various types, for
332 example the argument and local variables areas of inlined functions. */
333 if (t1 == 0 && t2 == 0)
336 /* If one or the other has readonly fields or is readonly,
337 then they may not conflict. */
338 if ((t1 != 0 && readonly_fields_p (t1))
339 || (t2 != 0 && readonly_fields_p (t2))
340 || (t1 != 0 && lang_hooks.honor_readonly && TYPE_READONLY (t1))
341 || (t2 != 0 && lang_hooks.honor_readonly && TYPE_READONLY (t2)))
344 /* If they are the same type, they must conflict. */
346 /* Likewise if both are volatile. */
347 || (t1 != 0 && TYPE_VOLATILE (t1) && t2 != 0 && TYPE_VOLATILE (t2)))
350 /* If one is aggregate and the other is scalar then they may not
352 if ((t1 != 0 && AGGREGATE_TYPE_P (t1))
353 != (t2 != 0 && AGGREGATE_TYPE_P (t2)))
356 /* Otherwise they conflict only if the alias sets conflict. */
357 return alias_sets_conflict_p (t1 ? get_alias_set (t1) : 0,
358 t2 ? get_alias_set (t2) : 0);
361 /* T is an expression with pointer type. Find the DECL on which this
362 expression is based. (For example, in `a[i]' this would be `a'.)
363 If there is no such DECL, or a unique decl cannot be determined,
364 NULL_TREE is returned. */
372 if (t == 0 || t == error_mark_node || ! POINTER_TYPE_P (TREE_TYPE (t)))
375 /* If this is a declaration, return it. */
376 if (TREE_CODE_CLASS (TREE_CODE (t)) == 'd')
379 /* Handle general expressions. It would be nice to deal with
380 COMPONENT_REFs here. If we could tell that `a' and `b' were the
381 same, then `a->f' and `b->f' are also the same. */
382 switch (TREE_CODE_CLASS (TREE_CODE (t)))
385 return find_base_decl (TREE_OPERAND (t, 0));
388 /* Return 0 if found in neither or both are the same. */
389 d0 = find_base_decl (TREE_OPERAND (t, 0));
390 d1 = find_base_decl (TREE_OPERAND (t, 1));
401 d0 = find_base_decl (TREE_OPERAND (t, 0));
402 d1 = find_base_decl (TREE_OPERAND (t, 1));
403 d2 = find_base_decl (TREE_OPERAND (t, 2));
405 /* Set any nonzero values from the last, then from the first. */
406 if (d1 == 0) d1 = d2;
407 if (d0 == 0) d0 = d1;
408 if (d1 == 0) d1 = d0;
409 if (d2 == 0) d2 = d1;
411 /* At this point all are nonzero or all are zero. If all three are the
412 same, return it. Otherwise, return zero. */
413 return (d0 == d1 && d1 == d2) ? d0 : 0;
420 /* Return 1 if all the nested component references handled by
421 get_inner_reference in T are such that we can address the object in T. */
427 /* If we're at the end, it is vacuously addressable. */
428 if (! handled_component_p (t))
431 /* Bitfields are never addressable. */
432 else if (TREE_CODE (t) == BIT_FIELD_REF)
435 /* Fields are addressable unless they are marked as nonaddressable or
436 the containing type has alias set 0. */
437 else if (TREE_CODE (t) == COMPONENT_REF
438 && ! DECL_NONADDRESSABLE_P (TREE_OPERAND (t, 1))
439 && get_alias_set (TREE_TYPE (TREE_OPERAND (t, 0))) != 0
440 && can_address_p (TREE_OPERAND (t, 0)))
443 /* Likewise for arrays. */
444 else if ((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
445 && ! TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t, 0)))
446 && get_alias_set (TREE_TYPE (TREE_OPERAND (t, 0))) != 0
447 && can_address_p (TREE_OPERAND (t, 0)))
453 /* Return the alias set for T, which may be either a type or an
454 expression. Call language-specific routine for help, if needed. */
462 /* If we're not doing any alias analysis, just assume everything
463 aliases everything else. Also return 0 if this or its type is
465 if (! flag_strict_aliasing || t == error_mark_node
467 && (TREE_TYPE (t) == 0 || TREE_TYPE (t) == error_mark_node)))
470 /* We can be passed either an expression or a type. This and the
471 language-specific routine may make mutually-recursive calls to each other
472 to figure out what to do. At each juncture, we see if this is a tree
473 that the language may need to handle specially. First handle things that
478 tree placeholder_ptr = 0;
480 /* Remove any nops, then give the language a chance to do
481 something with this tree before we look at it. */
483 set = (*lang_hooks.get_alias_set) (t);
487 /* First see if the actual object referenced is an INDIRECT_REF from a
488 restrict-qualified pointer or a "void *". Replace
489 PLACEHOLDER_EXPRs. */
490 while (TREE_CODE (inner) == PLACEHOLDER_EXPR
491 || handled_component_p (inner))
493 if (TREE_CODE (inner) == PLACEHOLDER_EXPR)
494 inner = find_placeholder (inner, &placeholder_ptr);
496 inner = TREE_OPERAND (inner, 0);
501 /* Check for accesses through restrict-qualified pointers. */
502 if (TREE_CODE (inner) == INDIRECT_REF)
504 tree decl = find_base_decl (TREE_OPERAND (inner, 0));
506 if (decl && DECL_POINTER_ALIAS_SET_KNOWN_P (decl))
508 /* If we haven't computed the actual alias set, do it now. */
509 if (DECL_POINTER_ALIAS_SET (decl) == -2)
511 /* No two restricted pointers can point at the same thing.
512 However, a restricted pointer can point at the same thing
513 as an unrestricted pointer, if that unrestricted pointer
514 is based on the restricted pointer. So, we make the
515 alias set for the restricted pointer a subset of the
516 alias set for the type pointed to by the type of the
518 HOST_WIDE_INT pointed_to_alias_set
519 = get_alias_set (TREE_TYPE (TREE_TYPE (decl)));
521 if (pointed_to_alias_set == 0)
522 /* It's not legal to make a subset of alias set zero. */
526 DECL_POINTER_ALIAS_SET (decl) = new_alias_set ();
527 record_alias_subset (pointed_to_alias_set,
528 DECL_POINTER_ALIAS_SET (decl));
532 /* We use the alias set indicated in the declaration. */
533 return DECL_POINTER_ALIAS_SET (decl);
536 /* If we have an INDIRECT_REF via a void pointer, we don't
537 know anything about what that might alias. */
538 else if (TREE_CODE (TREE_TYPE (inner)) == VOID_TYPE)
542 /* Otherwise, pick up the outermost object that we could have a pointer
543 to, processing conversion and PLACEHOLDER_EXPR as above. */
545 while (TREE_CODE (t) == PLACEHOLDER_EXPR
546 || (handled_component_p (t) && ! can_address_p (t)))
548 if (TREE_CODE (t) == PLACEHOLDER_EXPR)
549 t = find_placeholder (t, &placeholder_ptr);
551 t = TREE_OPERAND (t, 0);
556 /* If we've already determined the alias set for a decl, just return
557 it. This is necessary for C++ anonymous unions, whose component
558 variables don't look like union members (boo!). */
559 if (TREE_CODE (t) == VAR_DECL
560 && DECL_RTL_SET_P (t) && GET_CODE (DECL_RTL (t)) == MEM)
561 return MEM_ALIAS_SET (DECL_RTL (t));
563 /* Now all we care about is the type. */
567 /* Variant qualifiers don't affect the alias set, so get the main
568 variant. If this is a type with a known alias set, return it. */
569 t = TYPE_MAIN_VARIANT (t);
570 if (TYPE_ALIAS_SET_KNOWN_P (t))
571 return TYPE_ALIAS_SET (t);
573 /* See if the language has special handling for this type. */
574 set = (*lang_hooks.get_alias_set) (t);
578 /* There are no objects of FUNCTION_TYPE, so there's no point in
579 using up an alias set for them. (There are, of course, pointers
580 and references to functions, but that's different.) */
581 else if (TREE_CODE (t) == FUNCTION_TYPE)
584 /* Unless the language specifies otherwise, let vector types alias
585 their components. This avoids some nasty type punning issues in
586 normal usage. And indeed lets vectors be treated more like an
588 else if (TREE_CODE (t) == VECTOR_TYPE)
589 set = get_alias_set (TREE_TYPE (t));
592 /* Otherwise make a new alias set for this type. */
593 set = new_alias_set ();
595 TYPE_ALIAS_SET (t) = set;
597 /* If this is an aggregate type, we must record any component aliasing
599 if (AGGREGATE_TYPE_P (t) || TREE_CODE (t) == COMPLEX_TYPE)
600 record_component_aliases (t);
605 /* Return a brand-new alias set. */
610 static HOST_WIDE_INT last_alias_set;
612 if (flag_strict_aliasing)
613 return ++last_alias_set;
618 /* Indicate that things in SUBSET can alias things in SUPERSET, but
619 not vice versa. For example, in C, a store to an `int' can alias a
620 structure containing an `int', but not vice versa. Here, the
621 structure would be the SUPERSET and `int' the SUBSET. This
622 function should be called only once per SUPERSET/SUBSET pair.
624 It is illegal for SUPERSET to be zero; everything is implicitly a
625 subset of alias set zero. */
628 record_alias_subset (superset, subset)
629 HOST_WIDE_INT superset;
630 HOST_WIDE_INT subset;
632 alias_set_entry superset_entry;
633 alias_set_entry subset_entry;
635 /* It is possible in complex type situations for both sets to be the same,
636 in which case we can ignore this operation. */
637 if (superset == subset)
643 superset_entry = get_alias_set_entry (superset);
644 if (superset_entry == 0)
646 /* Create an entry for the SUPERSET, so that we have a place to
647 attach the SUBSET. */
649 = (alias_set_entry) xmalloc (sizeof (struct alias_set_entry));
650 superset_entry->alias_set = superset;
651 superset_entry->children
652 = splay_tree_new (splay_tree_compare_ints, 0, 0);
653 superset_entry->has_zero_child = 0;
654 splay_tree_insert (alias_sets, (splay_tree_key) superset,
655 (splay_tree_value) superset_entry);
659 superset_entry->has_zero_child = 1;
662 subset_entry = get_alias_set_entry (subset);
663 /* If there is an entry for the subset, enter all of its children
664 (if they are not already present) as children of the SUPERSET. */
667 if (subset_entry->has_zero_child)
668 superset_entry->has_zero_child = 1;
670 splay_tree_foreach (subset_entry->children, insert_subset_children,
671 superset_entry->children);
674 /* Enter the SUBSET itself as a child of the SUPERSET. */
675 splay_tree_insert (superset_entry->children,
676 (splay_tree_key) subset, 0);
680 /* Record that component types of TYPE, if any, are part of that type for
681 aliasing purposes. For record types, we only record component types
682 for fields that are marked addressable. For array types, we always
683 record the component types, so the front end should not call this
684 function if the individual component aren't addressable. */
687 record_component_aliases (type)
690 HOST_WIDE_INT superset = get_alias_set (type);
696 switch (TREE_CODE (type))
699 if (! TYPE_NONALIASED_COMPONENT (type))
700 record_alias_subset (superset, get_alias_set (TREE_TYPE (type)));
705 case QUAL_UNION_TYPE:
706 /* Recursively record aliases for the base classes, if there are any */
707 if (TYPE_BINFO (type) != NULL && TYPE_BINFO_BASETYPES (type) != NULL)
710 for (i = 0; i < TREE_VEC_LENGTH (TYPE_BINFO_BASETYPES (type)); i++)
712 tree binfo = TREE_VEC_ELT (TYPE_BINFO_BASETYPES (type), i);
713 record_alias_subset (superset,
714 get_alias_set (BINFO_TYPE (binfo)));
717 for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field))
718 if (TREE_CODE (field) == FIELD_DECL && ! DECL_NONADDRESSABLE_P (field))
719 record_alias_subset (superset, get_alias_set (TREE_TYPE (field)));
723 record_alias_subset (superset, get_alias_set (TREE_TYPE (type)));
731 /* Allocate an alias set for use in storing and reading from the varargs
735 get_varargs_alias_set ()
737 static HOST_WIDE_INT set = -1;
740 set = new_alias_set ();
745 /* Likewise, but used for the fixed portions of the frame, e.g., register
749 get_frame_alias_set ()
751 static HOST_WIDE_INT set = -1;
754 set = new_alias_set ();
759 /* Inside SRC, the source of a SET, find a base address. */
762 find_base_value (src)
767 switch (GET_CODE (src))
775 /* At the start of a function, argument registers have known base
776 values which may be lost later. Returning an ADDRESS
777 expression here allows optimization based on argument values
778 even when the argument registers are used for other purposes. */
779 if (regno < FIRST_PSEUDO_REGISTER && copying_arguments)
780 return new_reg_base_value[regno];
782 /* If a pseudo has a known base value, return it. Do not do this
783 for non-fixed hard regs since it can result in a circular
784 dependency chain for registers which have values at function entry.
786 The test above is not sufficient because the scheduler may move
787 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
788 if ((regno >= FIRST_PSEUDO_REGISTER || fixed_regs[regno])
789 && regno < reg_base_value_size)
791 /* If we're inside init_alias_analysis, use new_reg_base_value
792 to reduce the number of relaxation iterations. */
793 if (new_reg_base_value && new_reg_base_value[regno]
794 && REG_N_SETS (regno) == 1)
795 return new_reg_base_value[regno];
797 if (reg_base_value[regno])
798 return reg_base_value[regno];
804 /* Check for an argument passed in memory. Only record in the
805 copying-arguments block; it is too hard to track changes
807 if (copying_arguments
808 && (XEXP (src, 0) == arg_pointer_rtx
809 || (GET_CODE (XEXP (src, 0)) == PLUS
810 && XEXP (XEXP (src, 0), 0) == arg_pointer_rtx)))
811 return gen_rtx_ADDRESS (VOIDmode, src);
816 if (GET_CODE (src) != PLUS && GET_CODE (src) != MINUS)
819 /* ... fall through ... */
824 rtx temp, src_0 = XEXP (src, 0), src_1 = XEXP (src, 1);
826 /* If either operand is a REG that is a known pointer, then it
828 if (REG_P (src_0) && REG_POINTER (src_0))
829 return find_base_value (src_0);
830 if (REG_P (src_1) && REG_POINTER (src_1))
831 return find_base_value (src_1);
833 /* If either operand is a REG, then see if we already have
834 a known value for it. */
837 temp = find_base_value (src_0);
844 temp = find_base_value (src_1);
849 /* If either base is named object or a special address
850 (like an argument or stack reference), then use it for the
853 && (GET_CODE (src_0) == SYMBOL_REF
854 || GET_CODE (src_0) == LABEL_REF
855 || (GET_CODE (src_0) == ADDRESS
856 && GET_MODE (src_0) != VOIDmode)))
860 && (GET_CODE (src_1) == SYMBOL_REF
861 || GET_CODE (src_1) == LABEL_REF
862 || (GET_CODE (src_1) == ADDRESS
863 && GET_MODE (src_1) != VOIDmode)))
866 /* Guess which operand is the base address:
867 If either operand is a symbol, then it is the base. If
868 either operand is a CONST_INT, then the other is the base. */
869 if (GET_CODE (src_1) == CONST_INT || CONSTANT_P (src_0))
870 return find_base_value (src_0);
871 else if (GET_CODE (src_0) == CONST_INT || CONSTANT_P (src_1))
872 return find_base_value (src_1);
878 /* The standard form is (lo_sum reg sym) so look only at the
880 return find_base_value (XEXP (src, 1));
883 /* If the second operand is constant set the base
884 address to the first operand. */
885 if (GET_CODE (XEXP (src, 1)) == CONST_INT && INTVAL (XEXP (src, 1)) != 0)
886 return find_base_value (XEXP (src, 0));
890 if (GET_MODE_SIZE (GET_MODE (src)) < GET_MODE_SIZE (Pmode))
900 return find_base_value (XEXP (src, 0));
903 case SIGN_EXTEND: /* used for NT/Alpha pointers */
905 rtx temp = find_base_value (XEXP (src, 0));
907 #ifdef POINTERS_EXTEND_UNSIGNED
908 if (temp != 0 && CONSTANT_P (temp) && GET_MODE (temp) != Pmode)
909 temp = convert_memory_address (Pmode, temp);
922 /* Called from init_alias_analysis indirectly through note_stores. */
924 /* While scanning insns to find base values, reg_seen[N] is nonzero if
925 register N has been set in this function. */
926 static char *reg_seen;
928 /* Addresses which are known not to alias anything else are identified
929 by a unique integer. */
930 static int unique_id;
933 record_set (dest, set, data)
935 void *data ATTRIBUTE_UNUSED;
941 if (GET_CODE (dest) != REG)
944 regno = REGNO (dest);
946 if (regno >= reg_base_value_size)
949 /* If this spans multiple hard registers, then we must indicate that every
950 register has an unusable value. */
951 if (regno < FIRST_PSEUDO_REGISTER)
952 n = HARD_REGNO_NREGS (regno, GET_MODE (dest));
959 reg_seen[regno + n] = 1;
960 new_reg_base_value[regno + n] = 0;
967 /* A CLOBBER wipes out any old value but does not prevent a previously
968 unset register from acquiring a base address (i.e. reg_seen is not
970 if (GET_CODE (set) == CLOBBER)
972 new_reg_base_value[regno] = 0;
981 new_reg_base_value[regno] = 0;
985 new_reg_base_value[regno] = gen_rtx_ADDRESS (Pmode,
986 GEN_INT (unique_id++));
990 /* This is not the first set. If the new value is not related to the
991 old value, forget the base value. Note that the following code is
993 extern int x, y; int *p = &x; p += (&y-&x);
994 ANSI C does not allow computing the difference of addresses
995 of distinct top level objects. */
996 if (new_reg_base_value[regno])
997 switch (GET_CODE (src))
1001 if (XEXP (src, 0) != dest && XEXP (src, 1) != dest)
1002 new_reg_base_value[regno] = 0;
1005 /* If the value we add in the PLUS is also a valid base value,
1006 this might be the actual base value, and the original value
1009 rtx other = NULL_RTX;
1011 if (XEXP (src, 0) == dest)
1012 other = XEXP (src, 1);
1013 else if (XEXP (src, 1) == dest)
1014 other = XEXP (src, 0);
1016 if (! other || find_base_value (other))
1017 new_reg_base_value[regno] = 0;
1021 if (XEXP (src, 0) != dest || GET_CODE (XEXP (src, 1)) != CONST_INT)
1022 new_reg_base_value[regno] = 0;
1025 new_reg_base_value[regno] = 0;
1028 /* If this is the first set of a register, record the value. */
1029 else if ((regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
1030 && ! reg_seen[regno] && new_reg_base_value[regno] == 0)
1031 new_reg_base_value[regno] = find_base_value (src);
1033 reg_seen[regno] = 1;
1036 /* Called from loop optimization when a new pseudo-register is
1037 created. It indicates that REGNO is being set to VAL. f INVARIANT
1038 is true then this value also describes an invariant relationship
1039 which can be used to deduce that two registers with unknown values
1043 record_base_value (regno, val, invariant)
1048 if (regno >= reg_base_value_size)
1051 if (invariant && alias_invariant)
1052 alias_invariant[regno] = val;
1054 if (GET_CODE (val) == REG)
1056 if (REGNO (val) < reg_base_value_size)
1057 reg_base_value[regno] = reg_base_value[REGNO (val)];
1062 reg_base_value[regno] = find_base_value (val);
1065 /* Clear alias info for a register. This is used if an RTL transformation
1066 changes the value of a register. This is used in flow by AUTO_INC_DEC
1067 optimizations. We don't need to clear reg_base_value, since flow only
1068 changes the offset. */
1071 clear_reg_alias_info (reg)
1074 unsigned int regno = REGNO (reg);
1076 if (regno < reg_known_value_size && regno >= FIRST_PSEUDO_REGISTER)
1077 reg_known_value[regno] = reg;
1080 /* Returns a canonical version of X, from the point of view alias
1081 analysis. (For example, if X is a MEM whose address is a register,
1082 and the register has a known value (say a SYMBOL_REF), then a MEM
1083 whose address is the SYMBOL_REF is returned.) */
1089 /* Recursively look for equivalences. */
1090 if (GET_CODE (x) == REG && REGNO (x) >= FIRST_PSEUDO_REGISTER
1091 && REGNO (x) < reg_known_value_size)
1092 return reg_known_value[REGNO (x)] == x
1093 ? x : canon_rtx (reg_known_value[REGNO (x)]);
1094 else if (GET_CODE (x) == PLUS)
1096 rtx x0 = canon_rtx (XEXP (x, 0));
1097 rtx x1 = canon_rtx (XEXP (x, 1));
1099 if (x0 != XEXP (x, 0) || x1 != XEXP (x, 1))
1101 if (GET_CODE (x0) == CONST_INT)
1102 return plus_constant (x1, INTVAL (x0));
1103 else if (GET_CODE (x1) == CONST_INT)
1104 return plus_constant (x0, INTVAL (x1));
1105 return gen_rtx_PLUS (GET_MODE (x), x0, x1);
1109 /* This gives us much better alias analysis when called from
1110 the loop optimizer. Note we want to leave the original
1111 MEM alone, but need to return the canonicalized MEM with
1112 all the flags with their original values. */
1113 else if (GET_CODE (x) == MEM)
1114 x = replace_equiv_address_nv (x, canon_rtx (XEXP (x, 0)));
1119 /* Return 1 if X and Y are identical-looking rtx's.
1121 We use the data in reg_known_value above to see if two registers with
1122 different numbers are, in fact, equivalent. */
1125 rtx_equal_for_memref_p (x, y)
1133 if (x == 0 && y == 0)
1135 if (x == 0 || y == 0)
1144 code = GET_CODE (x);
1145 /* Rtx's of different codes cannot be equal. */
1146 if (code != GET_CODE (y))
1149 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1150 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1152 if (GET_MODE (x) != GET_MODE (y))
1155 /* Some RTL can be compared without a recursive examination. */
1159 return CSELIB_VAL_PTR (x) == CSELIB_VAL_PTR (y);
1162 return REGNO (x) == REGNO (y);
1165 return XEXP (x, 0) == XEXP (y, 0);
1168 return XSTR (x, 0) == XSTR (y, 0);
1172 /* There's no need to compare the contents of CONST_DOUBLEs or
1173 CONST_INTs because pointer equality is a good enough
1174 comparison for these nodes. */
1178 return (XINT (x, 1) == XINT (y, 1)
1179 && rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0)));
1185 /* For commutative operations, the RTX match if the operand match in any
1186 order. Also handle the simple binary and unary cases without a loop. */
1187 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
1188 return ((rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0))
1189 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1)))
1190 || (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 1))
1191 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 0))));
1192 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
1193 return (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0))
1194 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1)));
1195 else if (GET_RTX_CLASS (code) == '1')
1196 return rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0));
1198 /* Compare the elements. If any pair of corresponding elements
1199 fail to match, return 0 for the whole things.
1201 Limit cases to types which actually appear in addresses. */
1203 fmt = GET_RTX_FORMAT (code);
1204 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1209 if (XINT (x, i) != XINT (y, i))
1214 /* Two vectors must have the same length. */
1215 if (XVECLEN (x, i) != XVECLEN (y, i))
1218 /* And the corresponding elements must match. */
1219 for (j = 0; j < XVECLEN (x, i); j++)
1220 if (rtx_equal_for_memref_p (XVECEXP (x, i, j),
1221 XVECEXP (y, i, j)) == 0)
1226 if (rtx_equal_for_memref_p (XEXP (x, i), XEXP (y, i)) == 0)
1230 /* This can happen for asm operands. */
1232 if (strcmp (XSTR (x, i), XSTR (y, i)))
1236 /* This can happen for an asm which clobbers memory. */
1240 /* It is believed that rtx's at this level will never
1241 contain anything but integers and other rtx's,
1242 except for within LABEL_REFs and SYMBOL_REFs. */
1250 /* Given an rtx X, find a SYMBOL_REF or LABEL_REF within
1251 X and return it, or return 0 if none found. */
1254 find_symbolic_term (x)
1261 code = GET_CODE (x);
1262 if (code == SYMBOL_REF || code == LABEL_REF)
1264 if (GET_RTX_CLASS (code) == 'o')
1267 fmt = GET_RTX_FORMAT (code);
1268 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1274 t = find_symbolic_term (XEXP (x, i));
1278 else if (fmt[i] == 'E')
1289 struct elt_loc_list *l;
1291 #if defined (FIND_BASE_TERM)
1292 /* Try machine-dependent ways to find the base term. */
1293 x = FIND_BASE_TERM (x);
1296 switch (GET_CODE (x))
1299 return REG_BASE_VALUE (x);
1302 if (GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (Pmode))
1312 return find_base_term (XEXP (x, 0));
1315 case SIGN_EXTEND: /* Used for Alpha/NT pointers */
1317 rtx temp = find_base_term (XEXP (x, 0));
1319 #ifdef POINTERS_EXTEND_UNSIGNED
1320 if (temp != 0 && CONSTANT_P (temp) && GET_MODE (temp) != Pmode)
1321 temp = convert_memory_address (Pmode, temp);
1328 val = CSELIB_VAL_PTR (x);
1329 for (l = val->locs; l; l = l->next)
1330 if ((x = find_base_term (l->loc)) != 0)
1336 if (GET_CODE (x) != PLUS && GET_CODE (x) != MINUS)
1343 rtx tmp1 = XEXP (x, 0);
1344 rtx tmp2 = XEXP (x, 1);
1346 /* This is a little bit tricky since we have to determine which of
1347 the two operands represents the real base address. Otherwise this
1348 routine may return the index register instead of the base register.
1350 That may cause us to believe no aliasing was possible, when in
1351 fact aliasing is possible.
1353 We use a few simple tests to guess the base register. Additional
1354 tests can certainly be added. For example, if one of the operands
1355 is a shift or multiply, then it must be the index register and the
1356 other operand is the base register. */
1358 if (tmp1 == pic_offset_table_rtx && CONSTANT_P (tmp2))
1359 return find_base_term (tmp2);
1361 /* If either operand is known to be a pointer, then use it
1362 to determine the base term. */
1363 if (REG_P (tmp1) && REG_POINTER (tmp1))
1364 return find_base_term (tmp1);
1366 if (REG_P (tmp2) && REG_POINTER (tmp2))
1367 return find_base_term (tmp2);
1369 /* Neither operand was known to be a pointer. Go ahead and find the
1370 base term for both operands. */
1371 tmp1 = find_base_term (tmp1);
1372 tmp2 = find_base_term (tmp2);
1374 /* If either base term is named object or a special address
1375 (like an argument or stack reference), then use it for the
1378 && (GET_CODE (tmp1) == SYMBOL_REF
1379 || GET_CODE (tmp1) == LABEL_REF
1380 || (GET_CODE (tmp1) == ADDRESS
1381 && GET_MODE (tmp1) != VOIDmode)))
1385 && (GET_CODE (tmp2) == SYMBOL_REF
1386 || GET_CODE (tmp2) == LABEL_REF
1387 || (GET_CODE (tmp2) == ADDRESS
1388 && GET_MODE (tmp2) != VOIDmode)))
1391 /* We could not determine which of the two operands was the
1392 base register and which was the index. So we can determine
1393 nothing from the base alias check. */
1398 if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) != 0)
1399 return find_base_term (XEXP (x, 0));
1407 return REG_BASE_VALUE (frame_pointer_rtx);
1414 /* Return 0 if the addresses X and Y are known to point to different
1415 objects, 1 if they might be pointers to the same object. */
1418 base_alias_check (x, y, x_mode, y_mode)
1420 enum machine_mode x_mode, y_mode;
1422 rtx x_base = find_base_term (x);
1423 rtx y_base = find_base_term (y);
1425 /* If the address itself has no known base see if a known equivalent
1426 value has one. If either address still has no known base, nothing
1427 is known about aliasing. */
1432 if (! flag_expensive_optimizations || (x_c = canon_rtx (x)) == x)
1435 x_base = find_base_term (x_c);
1443 if (! flag_expensive_optimizations || (y_c = canon_rtx (y)) == y)
1446 y_base = find_base_term (y_c);
1451 /* If the base addresses are equal nothing is known about aliasing. */
1452 if (rtx_equal_p (x_base, y_base))
1455 /* The base addresses of the read and write are different expressions.
1456 If they are both symbols and they are not accessed via AND, there is
1457 no conflict. We can bring knowledge of object alignment into play
1458 here. For example, on alpha, "char a, b;" can alias one another,
1459 though "char a; long b;" cannot. */
1460 if (GET_CODE (x_base) != ADDRESS && GET_CODE (y_base) != ADDRESS)
1462 if (GET_CODE (x) == AND && GET_CODE (y) == AND)
1464 if (GET_CODE (x) == AND
1465 && (GET_CODE (XEXP (x, 1)) != CONST_INT
1466 || (int) GET_MODE_UNIT_SIZE (y_mode) < -INTVAL (XEXP (x, 1))))
1468 if (GET_CODE (y) == AND
1469 && (GET_CODE (XEXP (y, 1)) != CONST_INT
1470 || (int) GET_MODE_UNIT_SIZE (x_mode) < -INTVAL (XEXP (y, 1))))
1472 /* Differing symbols never alias. */
1476 /* If one address is a stack reference there can be no alias:
1477 stack references using different base registers do not alias,
1478 a stack reference can not alias a parameter, and a stack reference
1479 can not alias a global. */
1480 if ((GET_CODE (x_base) == ADDRESS && GET_MODE (x_base) == Pmode)
1481 || (GET_CODE (y_base) == ADDRESS && GET_MODE (y_base) == Pmode))
1484 if (! flag_argument_noalias)
1487 if (flag_argument_noalias > 1)
1490 /* Weak noalias assertion (arguments are distinct, but may match globals). */
1491 return ! (GET_MODE (x_base) == VOIDmode && GET_MODE (y_base) == VOIDmode);
1494 /* Convert the address X into something we can use. This is done by returning
1495 it unchanged unless it is a value; in the latter case we call cselib to get
1496 a more useful rtx. */
1503 struct elt_loc_list *l;
1505 if (GET_CODE (x) != VALUE)
1507 v = CSELIB_VAL_PTR (x);
1508 for (l = v->locs; l; l = l->next)
1509 if (CONSTANT_P (l->loc))
1511 for (l = v->locs; l; l = l->next)
1512 if (GET_CODE (l->loc) != REG && GET_CODE (l->loc) != MEM)
1515 return v->locs->loc;
1519 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
1520 where SIZE is the size in bytes of the memory reference. If ADDR
1521 is not modified by the memory reference then ADDR is returned. */
1524 addr_side_effect_eval (addr, size, n_refs)
1531 switch (GET_CODE (addr))
1534 offset = (n_refs + 1) * size;
1537 offset = -(n_refs + 1) * size;
1540 offset = n_refs * size;
1543 offset = -n_refs * size;
1551 addr = gen_rtx_PLUS (GET_MODE (addr), XEXP (addr, 0), GEN_INT (offset));
1553 addr = XEXP (addr, 0);
1558 /* Return nonzero if X and Y (memory addresses) could reference the
1559 same location in memory. C is an offset accumulator. When
1560 C is nonzero, we are testing aliases between X and Y + C.
1561 XSIZE is the size in bytes of the X reference,
1562 similarly YSIZE is the size in bytes for Y.
1564 If XSIZE or YSIZE is zero, we do not know the amount of memory being
1565 referenced (the reference was BLKmode), so make the most pessimistic
1568 If XSIZE or YSIZE is negative, we may access memory outside the object
1569 being referenced as a side effect. This can happen when using AND to
1570 align memory references, as is done on the Alpha.
1572 Nice to notice that varying addresses cannot conflict with fp if no
1573 local variables had their addresses taken, but that's too hard now. */
1576 memrefs_conflict_p (xsize, x, ysize, y, c)
1581 if (GET_CODE (x) == VALUE)
1583 if (GET_CODE (y) == VALUE)
1585 if (GET_CODE (x) == HIGH)
1587 else if (GET_CODE (x) == LO_SUM)
1590 x = canon_rtx (addr_side_effect_eval (x, xsize, 0));
1591 if (GET_CODE (y) == HIGH)
1593 else if (GET_CODE (y) == LO_SUM)
1596 y = canon_rtx (addr_side_effect_eval (y, ysize, 0));
1598 if (rtx_equal_for_memref_p (x, y))
1600 if (xsize <= 0 || ysize <= 0)
1602 if (c >= 0 && xsize > c)
1604 if (c < 0 && ysize+c > 0)
1609 /* This code used to check for conflicts involving stack references and
1610 globals but the base address alias code now handles these cases. */
1612 if (GET_CODE (x) == PLUS)
1614 /* The fact that X is canonicalized means that this
1615 PLUS rtx is canonicalized. */
1616 rtx x0 = XEXP (x, 0);
1617 rtx x1 = XEXP (x, 1);
1619 if (GET_CODE (y) == PLUS)
1621 /* The fact that Y is canonicalized means that this
1622 PLUS rtx is canonicalized. */
1623 rtx y0 = XEXP (y, 0);
1624 rtx y1 = XEXP (y, 1);
1626 if (rtx_equal_for_memref_p (x1, y1))
1627 return memrefs_conflict_p (xsize, x0, ysize, y0, c);
1628 if (rtx_equal_for_memref_p (x0, y0))
1629 return memrefs_conflict_p (xsize, x1, ysize, y1, c);
1630 if (GET_CODE (x1) == CONST_INT)
1632 if (GET_CODE (y1) == CONST_INT)
1633 return memrefs_conflict_p (xsize, x0, ysize, y0,
1634 c - INTVAL (x1) + INTVAL (y1));
1636 return memrefs_conflict_p (xsize, x0, ysize, y,
1639 else if (GET_CODE (y1) == CONST_INT)
1640 return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
1644 else if (GET_CODE (x1) == CONST_INT)
1645 return memrefs_conflict_p (xsize, x0, ysize, y, c - INTVAL (x1));
1647 else if (GET_CODE (y) == PLUS)
1649 /* The fact that Y is canonicalized means that this
1650 PLUS rtx is canonicalized. */
1651 rtx y0 = XEXP (y, 0);
1652 rtx y1 = XEXP (y, 1);
1654 if (GET_CODE (y1) == CONST_INT)
1655 return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
1660 if (GET_CODE (x) == GET_CODE (y))
1661 switch (GET_CODE (x))
1665 /* Handle cases where we expect the second operands to be the
1666 same, and check only whether the first operand would conflict
1669 rtx x1 = canon_rtx (XEXP (x, 1));
1670 rtx y1 = canon_rtx (XEXP (y, 1));
1671 if (! rtx_equal_for_memref_p (x1, y1))
1673 x0 = canon_rtx (XEXP (x, 0));
1674 y0 = canon_rtx (XEXP (y, 0));
1675 if (rtx_equal_for_memref_p (x0, y0))
1676 return (xsize == 0 || ysize == 0
1677 || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
1679 /* Can't properly adjust our sizes. */
1680 if (GET_CODE (x1) != CONST_INT)
1682 xsize /= INTVAL (x1);
1683 ysize /= INTVAL (x1);
1685 return memrefs_conflict_p (xsize, x0, ysize, y0, c);
1689 /* Are these registers known not to be equal? */
1690 if (alias_invariant)
1692 unsigned int r_x = REGNO (x), r_y = REGNO (y);
1693 rtx i_x, i_y; /* invariant relationships of X and Y */
1695 i_x = r_x >= reg_base_value_size ? 0 : alias_invariant[r_x];
1696 i_y = r_y >= reg_base_value_size ? 0 : alias_invariant[r_y];
1698 if (i_x == 0 && i_y == 0)
1701 if (! memrefs_conflict_p (xsize, i_x ? i_x : x,
1702 ysize, i_y ? i_y : y, c))
1711 /* Treat an access through an AND (e.g. a subword access on an Alpha)
1712 as an access with indeterminate size. Assume that references
1713 besides AND are aligned, so if the size of the other reference is
1714 at least as large as the alignment, assume no other overlap. */
1715 if (GET_CODE (x) == AND && GET_CODE (XEXP (x, 1)) == CONST_INT)
1717 if (GET_CODE (y) == AND || ysize < -INTVAL (XEXP (x, 1)))
1719 return memrefs_conflict_p (xsize, XEXP (x, 0), ysize, y, c);
1721 if (GET_CODE (y) == AND && GET_CODE (XEXP (y, 1)) == CONST_INT)
1723 /* ??? If we are indexing far enough into the array/structure, we
1724 may yet be able to determine that we can not overlap. But we
1725 also need to that we are far enough from the end not to overlap
1726 a following reference, so we do nothing with that for now. */
1727 if (GET_CODE (x) == AND || xsize < -INTVAL (XEXP (y, 1)))
1729 return memrefs_conflict_p (xsize, x, ysize, XEXP (y, 0), c);
1732 if (GET_CODE (x) == ADDRESSOF)
1734 if (y == frame_pointer_rtx
1735 || GET_CODE (y) == ADDRESSOF)
1736 return xsize <= 0 || ysize <= 0;
1738 if (GET_CODE (y) == ADDRESSOF)
1740 if (x == frame_pointer_rtx)
1741 return xsize <= 0 || ysize <= 0;
1746 if (GET_CODE (x) == CONST_INT && GET_CODE (y) == CONST_INT)
1748 c += (INTVAL (y) - INTVAL (x));
1749 return (xsize <= 0 || ysize <= 0
1750 || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
1753 if (GET_CODE (x) == CONST)
1755 if (GET_CODE (y) == CONST)
1756 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
1757 ysize, canon_rtx (XEXP (y, 0)), c);
1759 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
1762 if (GET_CODE (y) == CONST)
1763 return memrefs_conflict_p (xsize, x, ysize,
1764 canon_rtx (XEXP (y, 0)), c);
1767 return (xsize <= 0 || ysize <= 0
1768 || (rtx_equal_for_memref_p (x, y)
1769 && ((c >= 0 && xsize > c) || (c < 0 && ysize+c > 0))));
1776 /* Functions to compute memory dependencies.
1778 Since we process the insns in execution order, we can build tables
1779 to keep track of what registers are fixed (and not aliased), what registers
1780 are varying in known ways, and what registers are varying in unknown
1783 If both memory references are volatile, then there must always be a
1784 dependence between the two references, since their order can not be
1785 changed. A volatile and non-volatile reference can be interchanged
1788 A MEM_IN_STRUCT reference at a non-AND varying address can never
1789 conflict with a non-MEM_IN_STRUCT reference at a fixed address. We
1790 also must allow AND addresses, because they may generate accesses
1791 outside the object being referenced. This is used to generate
1792 aligned addresses from unaligned addresses, for instance, the alpha
1793 storeqi_unaligned pattern. */
1795 /* Read dependence: X is read after read in MEM takes place. There can
1796 only be a dependence here if both reads are volatile. */
1799 read_dependence (mem, x)
1803 return MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem);
1806 /* Returns MEM1 if and only if MEM1 is a scalar at a fixed address and
1807 MEM2 is a reference to a structure at a varying address, or returns
1808 MEM2 if vice versa. Otherwise, returns NULL_RTX. If a non-NULL
1809 value is returned MEM1 and MEM2 can never alias. VARIES_P is used
1810 to decide whether or not an address may vary; it should return
1811 nonzero whenever variation is possible.
1812 MEM1_ADDR and MEM2_ADDR are the addresses of MEM1 and MEM2. */
1815 fixed_scalar_and_varying_struct_p (mem1, mem2, mem1_addr, mem2_addr, varies_p)
1817 rtx mem1_addr, mem2_addr;
1818 int (*varies_p) PARAMS ((rtx, int));
1820 if (! flag_strict_aliasing)
1823 if (MEM_SCALAR_P (mem1) && MEM_IN_STRUCT_P (mem2)
1824 && !varies_p (mem1_addr, 1) && varies_p (mem2_addr, 1))
1825 /* MEM1 is a scalar at a fixed address; MEM2 is a struct at a
1829 if (MEM_IN_STRUCT_P (mem1) && MEM_SCALAR_P (mem2)
1830 && varies_p (mem1_addr, 1) && !varies_p (mem2_addr, 1))
1831 /* MEM2 is a scalar at a fixed address; MEM1 is a struct at a
1838 /* Returns nonzero if something about the mode or address format MEM1
1839 indicates that it might well alias *anything*. */
1842 aliases_everything_p (mem)
1845 if (GET_CODE (XEXP (mem, 0)) == AND)
1846 /* If the address is an AND, its very hard to know at what it is
1847 actually pointing. */
1853 /* Return true if we can determine that the fields referenced cannot
1854 overlap for any pair of objects. */
1857 nonoverlapping_component_refs_p (x, y)
1860 tree fieldx, fieldy, typex, typey, orig_y;
1864 /* The comparison has to be done at a common type, since we don't
1865 know how the inheritance hierarchy works. */
1869 fieldx = TREE_OPERAND (x, 1);
1870 typex = DECL_FIELD_CONTEXT (fieldx);
1875 fieldy = TREE_OPERAND (y, 1);
1876 typey = DECL_FIELD_CONTEXT (fieldy);
1881 y = TREE_OPERAND (y, 0);
1883 while (y && TREE_CODE (y) == COMPONENT_REF);
1885 x = TREE_OPERAND (x, 0);
1887 while (x && TREE_CODE (x) == COMPONENT_REF);
1889 /* Never found a common type. */
1893 /* If we're left with accessing different fields of a structure,
1895 if (TREE_CODE (typex) == RECORD_TYPE
1896 && fieldx != fieldy)
1899 /* The comparison on the current field failed. If we're accessing
1900 a very nested structure, look at the next outer level. */
1901 x = TREE_OPERAND (x, 0);
1902 y = TREE_OPERAND (y, 0);
1905 && TREE_CODE (x) == COMPONENT_REF
1906 && TREE_CODE (y) == COMPONENT_REF);
1911 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
1914 decl_for_component_ref (x)
1919 x = TREE_OPERAND (x, 0);
1921 while (x && TREE_CODE (x) == COMPONENT_REF);
1923 return x && DECL_P (x) ? x : NULL_TREE;
1926 /* Walk up the COMPONENT_REF list and adjust OFFSET to compensate for the
1927 offset of the field reference. */
1930 adjust_offset_for_component_ref (x, offset)
1934 HOST_WIDE_INT ioffset;
1939 ioffset = INTVAL (offset);
1942 tree field = TREE_OPERAND (x, 1);
1944 if (! host_integerp (DECL_FIELD_OFFSET (field), 1))
1946 ioffset += (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1947 + (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1950 x = TREE_OPERAND (x, 0);
1952 while (x && TREE_CODE (x) == COMPONENT_REF);
1954 return GEN_INT (ioffset);
1957 /* Return nonzero if we can determine the exprs corresponding to memrefs
1958 X and Y and they do not overlap. */
1961 nonoverlapping_memrefs_p (x, y)
1964 tree exprx = MEM_EXPR (x), expry = MEM_EXPR (y);
1967 rtx moffsetx, moffsety;
1968 HOST_WIDE_INT offsetx = 0, offsety = 0, sizex, sizey, tem;
1970 /* Unless both have exprs, we can't tell anything. */
1971 if (exprx == 0 || expry == 0)
1974 /* If both are field references, we may be able to determine something. */
1975 if (TREE_CODE (exprx) == COMPONENT_REF
1976 && TREE_CODE (expry) == COMPONENT_REF
1977 && nonoverlapping_component_refs_p (exprx, expry))
1980 /* If the field reference test failed, look at the DECLs involved. */
1981 moffsetx = MEM_OFFSET (x);
1982 if (TREE_CODE (exprx) == COMPONENT_REF)
1984 tree t = decl_for_component_ref (exprx);
1987 moffsetx = adjust_offset_for_component_ref (exprx, moffsetx);
1990 else if (TREE_CODE (exprx) == INDIRECT_REF)
1992 exprx = TREE_OPERAND (exprx, 0);
1993 if (flag_argument_noalias < 2
1994 || TREE_CODE (exprx) != PARM_DECL)
1998 moffsety = MEM_OFFSET (y);
1999 if (TREE_CODE (expry) == COMPONENT_REF)
2001 tree t = decl_for_component_ref (expry);
2004 moffsety = adjust_offset_for_component_ref (expry, moffsety);
2007 else if (TREE_CODE (expry) == INDIRECT_REF)
2009 expry = TREE_OPERAND (expry, 0);
2010 if (flag_argument_noalias < 2
2011 || TREE_CODE (expry) != PARM_DECL)
2015 if (! DECL_P (exprx) || ! DECL_P (expry))
2018 rtlx = DECL_RTL (exprx);
2019 rtly = DECL_RTL (expry);
2021 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
2022 can't overlap unless they are the same because we never reuse that part
2023 of the stack frame used for locals for spilled pseudos. */
2024 if ((GET_CODE (rtlx) != MEM || GET_CODE (rtly) != MEM)
2025 && ! rtx_equal_p (rtlx, rtly))
2028 /* Get the base and offsets of both decls. If either is a register, we
2029 know both are and are the same, so use that as the base. The only
2030 we can avoid overlap is if we can deduce that they are nonoverlapping
2031 pieces of that decl, which is very rare. */
2032 basex = GET_CODE (rtlx) == MEM ? XEXP (rtlx, 0) : rtlx;
2033 if (GET_CODE (basex) == PLUS && GET_CODE (XEXP (basex, 1)) == CONST_INT)
2034 offsetx = INTVAL (XEXP (basex, 1)), basex = XEXP (basex, 0);
2036 basey = GET_CODE (rtly) == MEM ? XEXP (rtly, 0) : rtly;
2037 if (GET_CODE (basey) == PLUS && GET_CODE (XEXP (basey, 1)) == CONST_INT)
2038 offsety = INTVAL (XEXP (basey, 1)), basey = XEXP (basey, 0);
2040 /* If the bases are different, we know they do not overlap if both
2041 are constants or if one is a constant and the other a pointer into the
2042 stack frame. Otherwise a different base means we can't tell if they
2044 if (! rtx_equal_p (basex, basey))
2045 return ((CONSTANT_P (basex) && CONSTANT_P (basey))
2046 || (CONSTANT_P (basex) && REG_P (basey)
2047 && REGNO_PTR_FRAME_P (REGNO (basey)))
2048 || (CONSTANT_P (basey) && REG_P (basex)
2049 && REGNO_PTR_FRAME_P (REGNO (basex))));
2051 sizex = (GET_CODE (rtlx) != MEM ? (int) GET_MODE_SIZE (GET_MODE (rtlx))
2052 : MEM_SIZE (rtlx) ? INTVAL (MEM_SIZE (rtlx))
2054 sizey = (GET_CODE (rtly) != MEM ? (int) GET_MODE_SIZE (GET_MODE (rtly))
2055 : MEM_SIZE (rtly) ? INTVAL (MEM_SIZE (rtly)) :
2058 /* If we have an offset for either memref, it can update the values computed
2061 offsetx += INTVAL (moffsetx), sizex -= INTVAL (moffsetx);
2063 offsety += INTVAL (moffsety), sizey -= INTVAL (moffsety);
2065 /* If a memref has both a size and an offset, we can use the smaller size.
2066 We can't do this if the offset isn't known because we must view this
2067 memref as being anywhere inside the DECL's MEM. */
2068 if (MEM_SIZE (x) && moffsetx)
2069 sizex = INTVAL (MEM_SIZE (x));
2070 if (MEM_SIZE (y) && moffsety)
2071 sizey = INTVAL (MEM_SIZE (y));
2073 /* Put the values of the memref with the lower offset in X's values. */
2074 if (offsetx > offsety)
2076 tem = offsetx, offsetx = offsety, offsety = tem;
2077 tem = sizex, sizex = sizey, sizey = tem;
2080 /* If we don't know the size of the lower-offset value, we can't tell
2081 if they conflict. Otherwise, we do the test. */
2082 return sizex >= 0 && offsety >= offsetx + sizex;
2085 /* True dependence: X is read after store in MEM takes place. */
2088 true_dependence (mem, mem_mode, x, varies)
2090 enum machine_mode mem_mode;
2092 int (*varies) PARAMS ((rtx, int));
2094 rtx x_addr, mem_addr;
2097 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2100 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2101 This is used in epilogue deallocation functions. */
2102 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
2104 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
2107 if (DIFFERENT_ALIAS_SETS_P (x, mem))
2110 /* Unchanging memory can't conflict with non-unchanging memory.
2111 A non-unchanging read can conflict with a non-unchanging write.
2112 An unchanging read can conflict with an unchanging write since
2113 there may be a single store to this address to initialize it.
2114 Note that an unchanging store can conflict with a non-unchanging read
2115 since we have to make conservative assumptions when we have a
2116 record with readonly fields and we are copying the whole thing.
2117 Just fall through to the code below to resolve potential conflicts.
2118 This won't handle all cases optimally, but the possible performance
2119 loss should be negligible. */
2120 if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem))
2123 if (nonoverlapping_memrefs_p (mem, x))
2126 if (mem_mode == VOIDmode)
2127 mem_mode = GET_MODE (mem);
2129 x_addr = get_addr (XEXP (x, 0));
2130 mem_addr = get_addr (XEXP (mem, 0));
2132 base = find_base_term (x_addr);
2133 if (base && (GET_CODE (base) == LABEL_REF
2134 || (GET_CODE (base) == SYMBOL_REF
2135 && CONSTANT_POOL_ADDRESS_P (base))))
2138 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode))
2141 x_addr = canon_rtx (x_addr);
2142 mem_addr = canon_rtx (mem_addr);
2144 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
2145 SIZE_FOR_MODE (x), x_addr, 0))
2148 if (aliases_everything_p (x))
2151 /* We cannot use aliases_everything_p to test MEM, since we must look
2152 at MEM_MODE, rather than GET_MODE (MEM). */
2153 if (mem_mode == QImode || GET_CODE (mem_addr) == AND)
2156 /* In true_dependence we also allow BLKmode to alias anything. Why
2157 don't we do this in anti_dependence and output_dependence? */
2158 if (mem_mode == BLKmode || GET_MODE (x) == BLKmode)
2161 return ! fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr,
2165 /* Canonical true dependence: X is read after store in MEM takes place.
2166 Variant of true_dependence which assumes MEM has already been
2167 canonicalized (hence we no longer do that here).
2168 The mem_addr argument has been added, since true_dependence computed
2169 this value prior to canonicalizing. */
2172 canon_true_dependence (mem, mem_mode, mem_addr, x, varies)
2173 rtx mem, mem_addr, x;
2174 enum machine_mode mem_mode;
2175 int (*varies) PARAMS ((rtx, int));
2179 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2182 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2183 This is used in epilogue deallocation functions. */
2184 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
2186 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
2189 if (DIFFERENT_ALIAS_SETS_P (x, mem))
2192 /* If X is an unchanging read, then it can't possibly conflict with any
2193 non-unchanging store. It may conflict with an unchanging write though,
2194 because there may be a single store to this address to initialize it.
2195 Just fall through to the code below to resolve the case where we have
2196 both an unchanging read and an unchanging write. This won't handle all
2197 cases optimally, but the possible performance loss should be
2199 if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem))
2202 if (nonoverlapping_memrefs_p (x, mem))
2205 x_addr = get_addr (XEXP (x, 0));
2207 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode))
2210 x_addr = canon_rtx (x_addr);
2211 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
2212 SIZE_FOR_MODE (x), x_addr, 0))
2215 if (aliases_everything_p (x))
2218 /* We cannot use aliases_everything_p to test MEM, since we must look
2219 at MEM_MODE, rather than GET_MODE (MEM). */
2220 if (mem_mode == QImode || GET_CODE (mem_addr) == AND)
2223 /* In true_dependence we also allow BLKmode to alias anything. Why
2224 don't we do this in anti_dependence and output_dependence? */
2225 if (mem_mode == BLKmode || GET_MODE (x) == BLKmode)
2228 return ! fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr,
2232 /* Returns nonzero if a write to X might alias a previous read from
2233 (or, if WRITEP is nonzero, a write to) MEM. */
2236 write_dependence_p (mem, x, writep)
2241 rtx x_addr, mem_addr;
2245 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2248 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything.
2249 This is used in epilogue deallocation functions. */
2250 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH)
2252 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH)
2255 if (DIFFERENT_ALIAS_SETS_P (x, mem))
2258 /* Unchanging memory can't conflict with non-unchanging memory. */
2259 if (RTX_UNCHANGING_P (x) != RTX_UNCHANGING_P (mem))
2262 /* If MEM is an unchanging read, then it can't possibly conflict with
2263 the store to X, because there is at most one store to MEM, and it must
2264 have occurred somewhere before MEM. */
2265 if (! writep && RTX_UNCHANGING_P (mem))
2268 if (nonoverlapping_memrefs_p (x, mem))
2271 x_addr = get_addr (XEXP (x, 0));
2272 mem_addr = get_addr (XEXP (mem, 0));
2276 base = find_base_term (mem_addr);
2277 if (base && (GET_CODE (base) == LABEL_REF
2278 || (GET_CODE (base) == SYMBOL_REF
2279 && CONSTANT_POOL_ADDRESS_P (base))))
2283 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x),
2287 x_addr = canon_rtx (x_addr);
2288 mem_addr = canon_rtx (mem_addr);
2290 if (!memrefs_conflict_p (SIZE_FOR_MODE (mem), mem_addr,
2291 SIZE_FOR_MODE (x), x_addr, 0))
2295 = fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr,
2298 return (!(fixed_scalar == mem && !aliases_everything_p (x))
2299 && !(fixed_scalar == x && !aliases_everything_p (mem)));
2302 /* Anti dependence: X is written after read in MEM takes place. */
2305 anti_dependence (mem, x)
2309 return write_dependence_p (mem, x, /*writep=*/0);
2312 /* Output dependence: X is written after store in MEM takes place. */
2315 output_dependence (mem, x)
2319 return write_dependence_p (mem, x, /*writep=*/1);
2322 /* A subroutine of nonlocal_mentioned_p, returns 1 if *LOC mentions
2323 something which is not local to the function and is not constant. */
2326 nonlocal_mentioned_p_1 (loc, data)
2328 void *data ATTRIBUTE_UNUSED;
2337 switch (GET_CODE (x))
2340 if (GET_CODE (SUBREG_REG (x)) == REG)
2342 /* Global registers are not local. */
2343 if (REGNO (SUBREG_REG (x)) < FIRST_PSEUDO_REGISTER
2344 && global_regs[subreg_regno (x)])
2352 /* Global registers are not local. */
2353 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2368 /* Constants in the function's constants pool are constant. */
2369 if (CONSTANT_POOL_ADDRESS_P (x))
2374 /* Non-constant calls and recursion are not local. */
2378 /* Be overly conservative and consider any volatile memory
2379 reference as not local. */
2380 if (MEM_VOLATILE_P (x))
2382 base = find_base_term (XEXP (x, 0));
2385 /* A Pmode ADDRESS could be a reference via the structure value
2386 address or static chain. Such memory references are nonlocal.
2388 Thus, we have to examine the contents of the ADDRESS to find
2389 out if this is a local reference or not. */
2390 if (GET_CODE (base) == ADDRESS
2391 && GET_MODE (base) == Pmode
2392 && (XEXP (base, 0) == stack_pointer_rtx
2393 || XEXP (base, 0) == arg_pointer_rtx
2394 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2395 || XEXP (base, 0) == hard_frame_pointer_rtx
2397 || XEXP (base, 0) == frame_pointer_rtx))
2399 /* Constants in the function's constant pool are constant. */
2400 if (GET_CODE (base) == SYMBOL_REF && CONSTANT_POOL_ADDRESS_P (base))
2405 case UNSPEC_VOLATILE:
2410 if (MEM_VOLATILE_P (x))
2422 /* Returns nonzero if X might mention something which is not
2423 local to the function and is not constant. */
2426 nonlocal_mentioned_p (x)
2432 if (GET_CODE (x) == CALL_INSN)
2434 if (! CONST_OR_PURE_CALL_P (x))
2436 x = CALL_INSN_FUNCTION_USAGE (x);
2444 return for_each_rtx (&x, nonlocal_mentioned_p_1, NULL);
2447 /* A subroutine of nonlocal_referenced_p, returns 1 if *LOC references
2448 something which is not local to the function and is not constant. */
2451 nonlocal_referenced_p_1 (loc, data)
2453 void *data ATTRIBUTE_UNUSED;
2460 switch (GET_CODE (x))
2466 return nonlocal_mentioned_p (x);
2469 /* Non-constant calls and recursion are not local. */
2473 if (nonlocal_mentioned_p (SET_SRC (x)))
2476 if (GET_CODE (SET_DEST (x)) == MEM)
2477 return nonlocal_mentioned_p (XEXP (SET_DEST (x), 0));
2479 /* If the destination is anything other than a CC0, PC,
2480 MEM, REG, or a SUBREG of a REG that occupies all of
2481 the REG, then X references nonlocal memory if it is
2482 mentioned in the destination. */
2483 if (GET_CODE (SET_DEST (x)) != CC0
2484 && GET_CODE (SET_DEST (x)) != PC
2485 && GET_CODE (SET_DEST (x)) != REG
2486 && ! (GET_CODE (SET_DEST (x)) == SUBREG
2487 && GET_CODE (SUBREG_REG (SET_DEST (x))) == REG
2488 && (((GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (x))))
2489 + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD)
2490 == ((GET_MODE_SIZE (GET_MODE (SET_DEST (x)))
2491 + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD))))
2492 return nonlocal_mentioned_p (SET_DEST (x));
2496 if (GET_CODE (XEXP (x, 0)) == MEM)
2497 return nonlocal_mentioned_p (XEXP (XEXP (x, 0), 0));
2501 return nonlocal_mentioned_p (XEXP (x, 0));
2504 case UNSPEC_VOLATILE:
2508 if (MEM_VOLATILE_P (x))
2520 /* Returns nonzero if X might reference something which is not
2521 local to the function and is not constant. */
2524 nonlocal_referenced_p (x)
2530 if (GET_CODE (x) == CALL_INSN)
2532 if (! CONST_OR_PURE_CALL_P (x))
2534 x = CALL_INSN_FUNCTION_USAGE (x);
2542 return for_each_rtx (&x, nonlocal_referenced_p_1, NULL);
2545 /* A subroutine of nonlocal_set_p, returns 1 if *LOC sets
2546 something which is not local to the function and is not constant. */
2549 nonlocal_set_p_1 (loc, data)
2551 void *data ATTRIBUTE_UNUSED;
2558 switch (GET_CODE (x))
2561 /* Non-constant calls and recursion are not local. */
2570 return nonlocal_mentioned_p (XEXP (x, 0));
2573 if (nonlocal_mentioned_p (SET_DEST (x)))
2575 return nonlocal_set_p (SET_SRC (x));
2578 return nonlocal_mentioned_p (XEXP (x, 0));
2584 case UNSPEC_VOLATILE:
2588 if (MEM_VOLATILE_P (x))
2600 /* Returns nonzero if X might set something which is not
2601 local to the function and is not constant. */
2610 if (GET_CODE (x) == CALL_INSN)
2612 if (! CONST_OR_PURE_CALL_P (x))
2614 x = CALL_INSN_FUNCTION_USAGE (x);
2622 return for_each_rtx (&x, nonlocal_set_p_1, NULL);
2625 /* Mark the function if it is constant. */
2628 mark_constant_function ()
2631 int nonlocal_memory_referenced;
2633 if (TREE_READONLY (current_function_decl)
2634 || DECL_IS_PURE (current_function_decl)
2635 || TREE_THIS_VOLATILE (current_function_decl)
2636 || TYPE_MODE (TREE_TYPE (current_function_decl)) == VOIDmode
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)
2671 DECL_IS_PURE (current_function_decl) = 1;
2673 TREE_READONLY (current_function_decl) = 1;
2682 #ifndef OUTGOING_REGNO
2683 #define OUTGOING_REGNO(N) N
2685 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2686 /* Check whether this register can hold an incoming pointer
2687 argument. FUNCTION_ARG_REGNO_P tests outgoing register
2688 numbers, so translate if necessary due to register windows. */
2689 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i))
2690 && HARD_REGNO_MODE_OK (i, Pmode))
2691 static_reg_base_value[i]
2692 = gen_rtx_ADDRESS (VOIDmode, gen_rtx_REG (Pmode, i));
2694 static_reg_base_value[STACK_POINTER_REGNUM]
2695 = gen_rtx_ADDRESS (Pmode, stack_pointer_rtx);
2696 static_reg_base_value[ARG_POINTER_REGNUM]
2697 = gen_rtx_ADDRESS (Pmode, arg_pointer_rtx);
2698 static_reg_base_value[FRAME_POINTER_REGNUM]
2699 = gen_rtx_ADDRESS (Pmode, frame_pointer_rtx);
2700 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2701 static_reg_base_value[HARD_FRAME_POINTER_REGNUM]
2702 = gen_rtx_ADDRESS (Pmode, hard_frame_pointer_rtx);
2705 alias_sets = splay_tree_new (splay_tree_compare_ints, 0, 0);
2708 /* Set MEMORY_MODIFIED when X modifies DATA (that is assumed
2709 to be memory reference. */
2710 static bool memory_modified;
2712 memory_modified_1 (x, pat, data)
2713 rtx x, pat ATTRIBUTE_UNUSED;
2716 if (GET_CODE (x) == MEM)
2718 if (anti_dependence (x, (rtx)data) || output_dependence (x, (rtx)data))
2719 memory_modified = true;
2724 /* Return true when INSN possibly modify memory contents of MEM
2725 (ie address can be modified). */
2727 memory_modified_in_insn_p (mem, insn)
2732 memory_modified = false;
2733 note_stores (PATTERN (insn), memory_modified_1, mem);
2734 return memory_modified;
2737 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
2741 init_alias_analysis ()
2743 int maxreg = max_reg_num ();
2749 timevar_push (TV_ALIAS_ANALYSIS);
2751 reg_known_value_size = maxreg;
2754 = (rtx *) xcalloc ((maxreg - FIRST_PSEUDO_REGISTER), sizeof (rtx))
2755 - FIRST_PSEUDO_REGISTER;
2757 = (char*) xcalloc ((maxreg - FIRST_PSEUDO_REGISTER), sizeof (char))
2758 - FIRST_PSEUDO_REGISTER;
2760 /* Overallocate reg_base_value to allow some growth during loop
2761 optimization. Loop unrolling can create a large number of
2763 reg_base_value_size = maxreg * 2;
2764 reg_base_value = (rtx *) ggc_alloc_cleared (reg_base_value_size
2767 new_reg_base_value = (rtx *) xmalloc (reg_base_value_size * sizeof (rtx));
2768 reg_seen = (char *) xmalloc (reg_base_value_size);
2769 if (! reload_completed && flag_old_unroll_loops)
2771 /* ??? Why are we realloc'ing if we're just going to zero it? */
2772 alias_invariant = (rtx *)xrealloc (alias_invariant,
2773 reg_base_value_size * sizeof (rtx));
2774 memset ((char *)alias_invariant, 0, reg_base_value_size * sizeof (rtx));
2777 /* The basic idea is that each pass through this loop will use the
2778 "constant" information from the previous pass to propagate alias
2779 information through another level of assignments.
2781 This could get expensive if the assignment chains are long. Maybe
2782 we should throttle the number of iterations, possibly based on
2783 the optimization level or flag_expensive_optimizations.
2785 We could propagate more information in the first pass by making use
2786 of REG_N_SETS to determine immediately that the alias information
2787 for a pseudo is "constant".
2789 A program with an uninitialized variable can cause an infinite loop
2790 here. Instead of doing a full dataflow analysis to detect such problems
2791 we just cap the number of iterations for the loop.
2793 The state of the arrays for the set chain in question does not matter
2794 since the program has undefined behavior. */
2799 /* Assume nothing will change this iteration of the loop. */
2802 /* We want to assign the same IDs each iteration of this loop, so
2803 start counting from zero each iteration of the loop. */
2806 /* We're at the start of the function each iteration through the
2807 loop, so we're copying arguments. */
2808 copying_arguments = true;
2810 /* Wipe the potential alias information clean for this pass. */
2811 memset ((char *) new_reg_base_value, 0, reg_base_value_size * sizeof (rtx));
2813 /* Wipe the reg_seen array clean. */
2814 memset ((char *) reg_seen, 0, reg_base_value_size);
2816 /* Mark all hard registers which may contain an address.
2817 The stack, frame and argument pointers may contain an address.
2818 An argument register which can hold a Pmode value may contain
2819 an address even if it is not in BASE_REGS.
2821 The address expression is VOIDmode for an argument and
2822 Pmode for other registers. */
2824 memcpy (new_reg_base_value, static_reg_base_value,
2825 FIRST_PSEUDO_REGISTER * sizeof (rtx));
2827 /* Walk the insns adding values to the new_reg_base_value array. */
2828 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2834 #if defined (HAVE_prologue) || defined (HAVE_epilogue)
2835 /* The prologue/epilogue insns are not threaded onto the
2836 insn chain until after reload has completed. Thus,
2837 there is no sense wasting time checking if INSN is in
2838 the prologue/epilogue until after reload has completed. */
2839 if (reload_completed
2840 && prologue_epilogue_contains (insn))
2844 /* If this insn has a noalias note, process it, Otherwise,
2845 scan for sets. A simple set will have no side effects
2846 which could change the base value of any other register. */
2848 if (GET_CODE (PATTERN (insn)) == SET
2849 && REG_NOTES (insn) != 0
2850 && find_reg_note (insn, REG_NOALIAS, NULL_RTX))
2851 record_set (SET_DEST (PATTERN (insn)), NULL_RTX, NULL);
2853 note_stores (PATTERN (insn), record_set, NULL);
2855 set = single_set (insn);
2858 && GET_CODE (SET_DEST (set)) == REG
2859 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER)
2861 unsigned int regno = REGNO (SET_DEST (set));
2862 rtx src = SET_SRC (set);
2864 if (REG_NOTES (insn) != 0
2865 && (((note = find_reg_note (insn, REG_EQUAL, 0)) != 0
2866 && REG_N_SETS (regno) == 1)
2867 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) != 0)
2868 && GET_CODE (XEXP (note, 0)) != EXPR_LIST
2869 && ! rtx_varies_p (XEXP (note, 0), 1)
2870 && ! reg_overlap_mentioned_p (SET_DEST (set), XEXP (note, 0)))
2872 reg_known_value[regno] = XEXP (note, 0);
2873 reg_known_equiv_p[regno] = REG_NOTE_KIND (note) == REG_EQUIV;
2875 else if (REG_N_SETS (regno) == 1
2876 && GET_CODE (src) == PLUS
2877 && GET_CODE (XEXP (src, 0)) == REG
2878 && REGNO (XEXP (src, 0)) >= FIRST_PSEUDO_REGISTER
2879 && (reg_known_value[REGNO (XEXP (src, 0))])
2880 && GET_CODE (XEXP (src, 1)) == CONST_INT)
2882 rtx op0 = XEXP (src, 0);
2883 op0 = reg_known_value[REGNO (op0)];
2884 reg_known_value[regno]
2885 = plus_constant (op0, INTVAL (XEXP (src, 1)));
2886 reg_known_equiv_p[regno] = 0;
2888 else if (REG_N_SETS (regno) == 1
2889 && ! rtx_varies_p (src, 1))
2891 reg_known_value[regno] = src;
2892 reg_known_equiv_p[regno] = 0;
2896 else if (GET_CODE (insn) == NOTE
2897 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_BEG)
2898 copying_arguments = false;
2901 /* Now propagate values from new_reg_base_value to reg_base_value. */
2902 for (ui = 0; ui < reg_base_value_size; ui++)
2904 if (new_reg_base_value[ui]
2905 && new_reg_base_value[ui] != reg_base_value[ui]
2906 && ! rtx_equal_p (new_reg_base_value[ui], reg_base_value[ui]))
2908 reg_base_value[ui] = new_reg_base_value[ui];
2913 while (changed && ++pass < MAX_ALIAS_LOOP_PASSES);
2915 /* Fill in the remaining entries. */
2916 for (i = FIRST_PSEUDO_REGISTER; i < maxreg; i++)
2917 if (reg_known_value[i] == 0)
2918 reg_known_value[i] = regno_reg_rtx[i];
2920 /* Simplify the reg_base_value array so that no register refers to
2921 another register, except to special registers indirectly through
2922 ADDRESS expressions.
2924 In theory this loop can take as long as O(registers^2), but unless
2925 there are very long dependency chains it will run in close to linear
2928 This loop may not be needed any longer now that the main loop does
2929 a better job at propagating alias information. */
2935 for (ui = 0; ui < reg_base_value_size; ui++)
2937 rtx base = reg_base_value[ui];
2938 if (base && GET_CODE (base) == REG)
2940 unsigned int base_regno = REGNO (base);
2941 if (base_regno == ui) /* register set from itself */
2942 reg_base_value[ui] = 0;
2944 reg_base_value[ui] = reg_base_value[base_regno];
2949 while (changed && pass < MAX_ALIAS_LOOP_PASSES);
2952 free (new_reg_base_value);
2953 new_reg_base_value = 0;
2956 timevar_pop (TV_ALIAS_ANALYSIS);
2960 end_alias_analysis ()
2962 free (reg_known_value + FIRST_PSEUDO_REGISTER);
2963 reg_known_value = 0;
2964 reg_known_value_size = 0;
2965 free (reg_known_equiv_p + FIRST_PSEUDO_REGISTER);
2966 reg_known_equiv_p = 0;
2968 reg_base_value_size = 0;
2969 if (alias_invariant)
2971 free (alias_invariant);
2972 alias_invariant = 0;
2976 #include "gt-alias.h"