1 /* Alias analysis for GNU C
2 Copyright (C) 1997, 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
3 Contributed by John Carr (jfc@mit.edu).
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
30 #include "hard-reg-set.h"
31 #include "basic-block.h"
36 #include "splay-tree.h"
38 #include "langhooks.h"
40 /* The alias sets assigned to MEMs assist the back-end in determining
41 which MEMs can alias which other MEMs. In general, two MEMs in
42 different alias sets cannot alias each other, with one important
43 exception. Consider something like:
45 struct S {int i; double d; };
47 a store to an `S' can alias something of either type `int' or type
48 `double'. (However, a store to an `int' cannot alias a `double'
49 and vice versa.) We indicate this via a tree structure that looks
57 (The arrows are directed and point downwards.)
58 In this situation we say the alias set for `struct S' is the
59 `superset' and that those for `int' and `double' are `subsets'.
61 To see whether two alias sets can point to the same memory, we must
62 see if either alias set is a subset of the other. We need not trace
63 past immediate descendents, however, since we propagate all
64 grandchildren up one level.
66 Alias set zero is implicitly a superset of all other alias sets.
67 However, this is no actual entry for alias set zero. It is an
68 error to attempt to explicitly construct a subset of zero. */
70 typedef struct alias_set_entry
72 /* The alias set number, as stored in MEM_ALIAS_SET. */
73 HOST_WIDE_INT alias_set;
75 /* The children of the alias set. These are not just the immediate
76 children, but, in fact, all descendents. So, if we have:
78 struct T { struct S s; float f; }
80 continuing our example above, the children here will be all of
81 `int', `double', `float', and `struct S'. */
84 /* Nonzero if would have a child of zero: this effectively makes this
85 alias set the same as alias set zero. */
89 static int rtx_equal_for_memref_p PARAMS ((rtx, rtx));
90 static rtx find_symbolic_term PARAMS ((rtx));
91 rtx get_addr PARAMS ((rtx));
92 static int memrefs_conflict_p PARAMS ((int, rtx, int, rtx,
94 static void record_set PARAMS ((rtx, rtx, void *));
95 static rtx find_base_term PARAMS ((rtx));
96 static int base_alias_check PARAMS ((rtx, rtx, enum machine_mode,
98 static rtx find_base_value PARAMS ((rtx));
99 static int mems_in_disjoint_alias_sets_p PARAMS ((rtx, rtx));
100 static int insert_subset_children PARAMS ((splay_tree_node, void*));
101 static tree find_base_decl PARAMS ((tree));
102 static alias_set_entry get_alias_set_entry PARAMS ((HOST_WIDE_INT));
103 static rtx fixed_scalar_and_varying_struct_p PARAMS ((rtx, rtx, rtx, rtx,
104 int (*) (rtx, int)));
105 static int aliases_everything_p PARAMS ((rtx));
106 static bool nonoverlapping_component_refs_p PARAMS ((tree, tree));
107 static tree decl_for_component_ref PARAMS ((tree));
108 static rtx adjust_offset_for_component_ref PARAMS ((tree, rtx));
109 static int nonoverlapping_memrefs_p PARAMS ((rtx, rtx));
110 static int write_dependence_p PARAMS ((rtx, rtx, int));
111 static int nonlocal_mentioned_p PARAMS ((rtx));
113 /* Set up all info needed to perform alias analysis on memory references. */
115 /* Returns the size in bytes of the mode of X. */
116 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
118 /* Returns nonzero if MEM1 and MEM2 do not alias because they are in
119 different alias sets. We ignore alias sets in functions making use
120 of variable arguments because the va_arg macros on some systems are
122 #define DIFFERENT_ALIAS_SETS_P(MEM1, MEM2) \
123 mems_in_disjoint_alias_sets_p (MEM1, MEM2)
125 /* Cap the number of passes we make over the insns propagating alias
126 information through set chains. 10 is a completely arbitrary choice. */
127 #define MAX_ALIAS_LOOP_PASSES 10
129 /* reg_base_value[N] gives an address to which register N is related.
130 If all sets after the first add or subtract to the current value
131 or otherwise modify it so it does not point to a different top level
132 object, reg_base_value[N] is equal to the address part of the source
135 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS
136 expressions represent certain special values: function arguments and
137 the stack, frame, and argument pointers.
139 The contents of an ADDRESS is not normally used, the mode of the
140 ADDRESS determines whether the ADDRESS is a function argument or some
141 other special value. Pointer equality, not rtx_equal_p, determines whether
142 two ADDRESS expressions refer to the same base address.
144 The only use of the contents of an ADDRESS is for determining if the
145 current function performs nonlocal memory memory references for the
146 purposes of marking the function as a constant function. */
148 static rtx *reg_base_value;
149 static rtx *new_reg_base_value;
150 static unsigned int reg_base_value_size; /* size of reg_base_value array */
152 #define REG_BASE_VALUE(X) \
153 (REGNO (X) < reg_base_value_size \
154 ? reg_base_value[REGNO (X)] : 0)
156 /* Vector of known invariant relationships between registers. Set in
157 loop unrolling. Indexed by register number, if nonzero the value
158 is an expression describing this register in terms of another.
160 The length of this array is REG_BASE_VALUE_SIZE.
162 Because this array contains only pseudo registers it has no effect
164 static rtx *alias_invariant;
166 /* Vector indexed by N giving the initial (unchanging) value known for
167 pseudo-register N. This array is initialized in
168 init_alias_analysis, and does not change until end_alias_analysis
170 rtx *reg_known_value;
172 /* Indicates number of valid entries in reg_known_value. */
173 static unsigned int reg_known_value_size;
175 /* Vector recording for each reg_known_value whether it is due to a
176 REG_EQUIV note. Future passes (viz., reload) may replace the
177 pseudo with the equivalent expression and so we account for the
178 dependences that would be introduced if that happens.
180 The REG_EQUIV notes created in assign_parms may mention the arg
181 pointer, and there are explicit insns in the RTL that modify the
182 arg pointer. Thus we must ensure that such insns don't get
183 scheduled across each other because that would invalidate the
184 REG_EQUIV notes. One could argue that the REG_EQUIV notes are
185 wrong, but solving the problem in the scheduler will likely give
186 better code, so we do it here. */
187 char *reg_known_equiv_p;
189 /* True when scanning insns from the start of the rtl to the
190 NOTE_INSN_FUNCTION_BEG note. */
191 static int copying_arguments;
193 /* The splay-tree used to store the various alias set entries. */
194 static splay_tree alias_sets;
196 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is
197 such an entry, or NULL otherwise. */
199 static alias_set_entry
200 get_alias_set_entry (alias_set)
201 HOST_WIDE_INT alias_set;
204 = splay_tree_lookup (alias_sets, (splay_tree_key) alias_set);
206 return sn != 0 ? ((alias_set_entry) sn->value) : 0;
209 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that
210 the two MEMs cannot alias each other. */
213 mems_in_disjoint_alias_sets_p (mem1, mem2)
217 #ifdef ENABLE_CHECKING
218 /* Perform a basic sanity check. Namely, that there are no alias sets
219 if we're not using strict aliasing. This helps to catch bugs
220 whereby someone uses PUT_CODE, but doesn't clear MEM_ALIAS_SET, or
221 where a MEM is allocated in some way other than by the use of
222 gen_rtx_MEM, and the MEM_ALIAS_SET is not cleared. If we begin to
223 use alias sets to indicate that spilled registers cannot alias each
224 other, we might need to remove this check. */
225 if (! flag_strict_aliasing
226 && (MEM_ALIAS_SET (mem1) != 0 || MEM_ALIAS_SET (mem2) != 0))
230 return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1), MEM_ALIAS_SET (mem2));
233 /* Insert the NODE into the splay tree given by DATA. Used by
234 record_alias_subset via splay_tree_foreach. */
237 insert_subset_children (node, data)
238 splay_tree_node node;
241 splay_tree_insert ((splay_tree) data, node->key, node->value);
246 /* Return 1 if the two specified alias sets may conflict. */
249 alias_sets_conflict_p (set1, set2)
250 HOST_WIDE_INT set1, set2;
254 /* If have no alias set information for one of the operands, we have
255 to assume it can alias anything. */
256 if (set1 == 0 || set2 == 0
257 /* If the two alias sets are the same, they may alias. */
261 /* See if the first alias set is a subset of the second. */
262 ase = get_alias_set_entry (set1);
264 && (ase->has_zero_child
265 || splay_tree_lookup (ase->children,
266 (splay_tree_key) set2)))
269 /* Now do the same, but with the alias sets reversed. */
270 ase = get_alias_set_entry (set2);
272 && (ase->has_zero_child
273 || splay_tree_lookup (ase->children,
274 (splay_tree_key) set1)))
277 /* The two alias sets are distinct and neither one is the
278 child of the other. Therefore, they cannot alias. */
282 /* Return 1 if TYPE is a RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE and has
283 has any readonly fields. If any of the fields have types that
284 contain readonly fields, return true as well. */
287 readonly_fields_p (type)
292 if (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE
293 && TREE_CODE (type) != QUAL_UNION_TYPE)
296 for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field))
297 if (TREE_CODE (field) == FIELD_DECL
298 && (TREE_READONLY (field)
299 || readonly_fields_p (TREE_TYPE (field))))
305 /* Return 1 if any MEM object of type T1 will always conflict (using the
306 dependency routines in this file) with any MEM object of type T2.
307 This is used when allocating temporary storage. If T1 and/or T2 are
308 NULL_TREE, it means we know nothing about the storage. */
311 objects_must_conflict_p (t1, t2)
314 /* If neither has a type specified, we don't know if they'll conflict
315 because we may be using them to store objects of various types, for
316 example the argument and local variables areas of inlined functions. */
317 if (t1 == 0 && t2 == 0)
320 /* If one or the other has readonly fields or is readonly,
321 then they may not conflict. */
322 if ((t1 != 0 && readonly_fields_p (t1))
323 || (t2 != 0 && readonly_fields_p (t2))
324 || (t1 != 0 && TYPE_READONLY (t1))
325 || (t2 != 0 && TYPE_READONLY (t2)))
328 /* If they are the same type, they must conflict. */
330 /* Likewise if both are volatile. */
331 || (t1 != 0 && TYPE_VOLATILE (t1) && t2 != 0 && TYPE_VOLATILE (t2)))
334 /* If one is aggregate and the other is scalar then they may not
336 if ((t1 != 0 && AGGREGATE_TYPE_P (t1))
337 != (t2 != 0 && AGGREGATE_TYPE_P (t2)))
340 /* Otherwise they conflict only if the alias sets conflict. */
341 return alias_sets_conflict_p (t1 ? get_alias_set (t1) : 0,
342 t2 ? get_alias_set (t2) : 0);
345 /* T is an expression with pointer type. Find the DECL on which this
346 expression is based. (For example, in `a[i]' this would be `a'.)
347 If there is no such DECL, or a unique decl cannot be determined,
348 NULL_TREE is returned. */
356 if (t == 0 || t == error_mark_node || ! POINTER_TYPE_P (TREE_TYPE (t)))
359 /* If this is a declaration, return it. */
360 if (TREE_CODE_CLASS (TREE_CODE (t)) == 'd')
363 /* Handle general expressions. It would be nice to deal with
364 COMPONENT_REFs here. If we could tell that `a' and `b' were the
365 same, then `a->f' and `b->f' are also the same. */
366 switch (TREE_CODE_CLASS (TREE_CODE (t)))
369 return find_base_decl (TREE_OPERAND (t, 0));
372 /* Return 0 if found in neither or both are the same. */
373 d0 = find_base_decl (TREE_OPERAND (t, 0));
374 d1 = find_base_decl (TREE_OPERAND (t, 1));
385 d0 = find_base_decl (TREE_OPERAND (t, 0));
386 d1 = find_base_decl (TREE_OPERAND (t, 1));
387 d2 = find_base_decl (TREE_OPERAND (t, 2));
389 /* Set any nonzero values from the last, then from the first. */
390 if (d1 == 0) d1 = d2;
391 if (d0 == 0) d0 = d1;
392 if (d1 == 0) d1 = d0;
393 if (d2 == 0) d2 = d1;
395 /* At this point all are nonzero or all are zero. If all three are the
396 same, return it. Otherwise, return zero. */
397 return (d0 == d1 && d1 == d2) ? d0 : 0;
404 /* Return 1 if all the nested component references handled by
405 get_inner_reference in T are such that we can address the object in T. */
411 /* If we're at the end, it is vacuously addressable. */
412 if (! handled_component_p (t))
415 /* Bitfields are never addressable. */
416 else if (TREE_CODE (t) == BIT_FIELD_REF)
419 /* Fields are addressable unless they are marked as nonaddressable or
420 the containing type has alias set 0. */
421 else if (TREE_CODE (t) == COMPONENT_REF
422 && ! DECL_NONADDRESSABLE_P (TREE_OPERAND (t, 1))
423 && get_alias_set (TREE_TYPE (TREE_OPERAND (t, 0))) != 0
424 && can_address_p (TREE_OPERAND (t, 0)))
427 /* Likewise for arrays. */
428 else if ((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
429 && ! TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t, 0)))
430 && get_alias_set (TREE_TYPE (TREE_OPERAND (t, 0))) != 0
431 && can_address_p (TREE_OPERAND (t, 0)))
437 /* Return the alias set for T, which may be either a type or an
438 expression. Call language-specific routine for help, if needed. */
446 /* If we're not doing any alias analysis, just assume everything
447 aliases everything else. Also return 0 if this or its type is
449 if (! flag_strict_aliasing || t == error_mark_node
451 && (TREE_TYPE (t) == 0 || TREE_TYPE (t) == error_mark_node)))
454 /* We can be passed either an expression or a type. This and the
455 language-specific routine may make mutually-recursive calls to each other
456 to figure out what to do. At each juncture, we see if this is a tree
457 that the language may need to handle specially. First handle things that
462 tree placeholder_ptr = 0;
464 /* Remove any nops, then give the language a chance to do
465 something with this tree before we look at it. */
467 set = (*lang_hooks.get_alias_set) (t);
471 /* First see if the actual object referenced is an INDIRECT_REF from a
472 restrict-qualified pointer or a "void *". Replace
473 PLACEHOLDER_EXPRs. */
474 while (TREE_CODE (inner) == PLACEHOLDER_EXPR
475 || handled_component_p (inner))
477 if (TREE_CODE (inner) == PLACEHOLDER_EXPR)
478 inner = find_placeholder (inner, &placeholder_ptr);
480 inner = TREE_OPERAND (inner, 0);
485 /* Check for accesses through restrict-qualified pointers. */
486 if (TREE_CODE (inner) == INDIRECT_REF)
488 tree decl = find_base_decl (TREE_OPERAND (inner, 0));
490 if (decl && DECL_POINTER_ALIAS_SET_KNOWN_P (decl))
492 /* If we haven't computed the actual alias set, do it now. */
493 if (DECL_POINTER_ALIAS_SET (decl) == -2)
495 /* No two restricted pointers can point at the same thing.
496 However, a restricted pointer can point at the same thing
497 as an unrestricted pointer, if that unrestricted pointer
498 is based on the restricted pointer. So, we make the
499 alias set for the restricted pointer a subset of the
500 alias set for the type pointed to by the type of the
502 HOST_WIDE_INT pointed_to_alias_set
503 = get_alias_set (TREE_TYPE (TREE_TYPE (decl)));
505 if (pointed_to_alias_set == 0)
506 /* It's not legal to make a subset of alias set zero. */
510 DECL_POINTER_ALIAS_SET (decl) = new_alias_set ();
511 record_alias_subset (pointed_to_alias_set,
512 DECL_POINTER_ALIAS_SET (decl));
516 /* We use the alias set indicated in the declaration. */
517 return DECL_POINTER_ALIAS_SET (decl);
520 /* If we have an INDIRECT_REF via a void pointer, we don't
521 know anything about what that might alias. */
522 else if (TREE_CODE (TREE_TYPE (inner)) == VOID_TYPE)
526 /* Otherwise, pick up the outermost object that we could have a pointer
527 to, processing conversion and PLACEHOLDER_EXPR as above. */
529 while (TREE_CODE (t) == PLACEHOLDER_EXPR
530 || (handled_component_p (t) && ! can_address_p (t)))
532 if (TREE_CODE (t) == PLACEHOLDER_EXPR)
533 t = find_placeholder (t, &placeholder_ptr);
535 t = TREE_OPERAND (t, 0);
540 /* If we've already determined the alias set for a decl, just return
541 it. This is necessary for C++ anonymous unions, whose component
542 variables don't look like union members (boo!). */
543 if (TREE_CODE (t) == VAR_DECL
544 && DECL_RTL_SET_P (t) && GET_CODE (DECL_RTL (t)) == MEM)
545 return MEM_ALIAS_SET (DECL_RTL (t));
547 /* Now all we care about is the type. */
551 /* Variant qualifiers don't affect the alias set, so get the main
552 variant. If this is a type with a known alias set, return it. */
553 t = TYPE_MAIN_VARIANT (t);
554 if (TYPE_ALIAS_SET_KNOWN_P (t))
555 return TYPE_ALIAS_SET (t);
557 /* See if the language has special handling for this type. */
558 set = (*lang_hooks.get_alias_set) (t);
562 /* There are no objects of FUNCTION_TYPE, so there's no point in
563 using up an alias set for them. (There are, of course, pointers
564 and references to functions, but that's different.) */
565 else if (TREE_CODE (t) == FUNCTION_TYPE)
568 /* Otherwise make a new alias set for this type. */
569 set = new_alias_set ();
571 TYPE_ALIAS_SET (t) = set;
573 /* If this is an aggregate type, we must record any component aliasing
575 if (AGGREGATE_TYPE_P (t) || TREE_CODE (t) == COMPLEX_TYPE)
576 record_component_aliases (t);
581 /* Return a brand-new alias set. */
586 static HOST_WIDE_INT last_alias_set;
588 if (flag_strict_aliasing)
589 return ++last_alias_set;
594 /* Indicate that things in SUBSET can alias things in SUPERSET, but
595 not vice versa. For example, in C, a store to an `int' can alias a
596 structure containing an `int', but not vice versa. Here, the
597 structure would be the SUPERSET and `int' the SUBSET. This
598 function should be called only once per SUPERSET/SUBSET pair.
600 It is illegal for SUPERSET to be zero; everything is implicitly a
601 subset of alias set zero. */
604 record_alias_subset (superset, subset)
605 HOST_WIDE_INT superset;
606 HOST_WIDE_INT subset;
608 alias_set_entry superset_entry;
609 alias_set_entry subset_entry;
611 /* It is possible in complex type situations for both sets to be the same,
612 in which case we can ignore this operation. */
613 if (superset == subset)
619 superset_entry = get_alias_set_entry (superset);
620 if (superset_entry == 0)
622 /* Create an entry for the SUPERSET, so that we have a place to
623 attach the SUBSET. */
625 = (alias_set_entry) xmalloc (sizeof (struct alias_set_entry));
626 superset_entry->alias_set = superset;
627 superset_entry->children
628 = splay_tree_new (splay_tree_compare_ints, 0, 0);
629 superset_entry->has_zero_child = 0;
630 splay_tree_insert (alias_sets, (splay_tree_key) superset,
631 (splay_tree_value) superset_entry);
635 superset_entry->has_zero_child = 1;
638 subset_entry = get_alias_set_entry (subset);
639 /* If there is an entry for the subset, enter all of its children
640 (if they are not already present) as children of the SUPERSET. */
643 if (subset_entry->has_zero_child)
644 superset_entry->has_zero_child = 1;
646 splay_tree_foreach (subset_entry->children, insert_subset_children,
647 superset_entry->children);
650 /* Enter the SUBSET itself as a child of the SUPERSET. */
651 splay_tree_insert (superset_entry->children,
652 (splay_tree_key) subset, 0);
656 /* Record that component types of TYPE, if any, are part of that type for
657 aliasing purposes. For record types, we only record component types
658 for fields that are marked addressable. For array types, we always
659 record the component types, so the front end should not call this
660 function if the individual component aren't addressable. */
663 record_component_aliases (type)
666 HOST_WIDE_INT superset = get_alias_set (type);
672 switch (TREE_CODE (type))
675 if (! TYPE_NONALIASED_COMPONENT (type))
676 record_alias_subset (superset, get_alias_set (TREE_TYPE (type)));
681 case QUAL_UNION_TYPE:
682 for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field))
683 if (TREE_CODE (field) == FIELD_DECL && ! DECL_NONADDRESSABLE_P (field))
684 record_alias_subset (superset, get_alias_set (TREE_TYPE (field)));
688 record_alias_subset (superset, get_alias_set (TREE_TYPE (type)));
696 /* Allocate an alias set for use in storing and reading from the varargs
700 get_varargs_alias_set ()
702 static HOST_WIDE_INT set = -1;
705 set = new_alias_set ();
710 /* Likewise, but used for the fixed portions of the frame, e.g., register
714 get_frame_alias_set ()
716 static HOST_WIDE_INT set = -1;
719 set = new_alias_set ();
724 /* Inside SRC, the source of a SET, find a base address. */
727 find_base_value (src)
731 switch (GET_CODE (src))
739 /* At the start of a function, argument registers have known base
740 values which may be lost later. Returning an ADDRESS
741 expression here allows optimization based on argument values
742 even when the argument registers are used for other purposes. */
743 if (regno < FIRST_PSEUDO_REGISTER && copying_arguments)
744 return new_reg_base_value[regno];
746 /* If a pseudo has a known base value, return it. Do not do this
747 for hard regs since it can result in a circular dependency
748 chain for registers which have values at function entry.
750 The test above is not sufficient because the scheduler may move
751 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */
752 if (regno >= FIRST_PSEUDO_REGISTER
753 && regno < reg_base_value_size
754 && reg_base_value[regno])
755 return reg_base_value[regno];
760 /* Check for an argument passed in memory. Only record in the
761 copying-arguments block; it is too hard to track changes
763 if (copying_arguments
764 && (XEXP (src, 0) == arg_pointer_rtx
765 || (GET_CODE (XEXP (src, 0)) == PLUS
766 && XEXP (XEXP (src, 0), 0) == arg_pointer_rtx)))
767 return gen_rtx_ADDRESS (VOIDmode, src);
772 if (GET_CODE (src) != PLUS && GET_CODE (src) != MINUS)
775 /* ... fall through ... */
780 rtx temp, src_0 = XEXP (src, 0), src_1 = XEXP (src, 1);
782 /* If either operand is a REG that is a known pointer, then it
784 if (REG_P (src_0) && REG_POINTER (src_0))
785 return find_base_value (src_0);
786 if (REG_P (src_1) && REG_POINTER (src_1))
787 return find_base_value (src_1);
789 /* If either operand is a REG, then see if we already have
790 a known value for it. */
793 temp = find_base_value (src_0);
800 temp = find_base_value (src_1);
805 /* If either base is named object or a special address
806 (like an argument or stack reference), then use it for the
809 && (GET_CODE (src_0) == SYMBOL_REF
810 || GET_CODE (src_0) == LABEL_REF
811 || (GET_CODE (src_0) == ADDRESS
812 && GET_MODE (src_0) != VOIDmode)))
816 && (GET_CODE (src_1) == SYMBOL_REF
817 || GET_CODE (src_1) == LABEL_REF
818 || (GET_CODE (src_1) == ADDRESS
819 && GET_MODE (src_1) != VOIDmode)))
822 /* Guess which operand is the base address:
823 If either operand is a symbol, then it is the base. If
824 either operand is a CONST_INT, then the other is the base. */
825 if (GET_CODE (src_1) == CONST_INT || CONSTANT_P (src_0))
826 return find_base_value (src_0);
827 else if (GET_CODE (src_0) == CONST_INT || CONSTANT_P (src_1))
828 return find_base_value (src_1);
834 /* The standard form is (lo_sum reg sym) so look only at the
836 return find_base_value (XEXP (src, 1));
839 /* If the second operand is constant set the base
840 address to the first operand. */
841 if (GET_CODE (XEXP (src, 1)) == CONST_INT && INTVAL (XEXP (src, 1)) != 0)
842 return find_base_value (XEXP (src, 0));
846 if (GET_MODE_SIZE (GET_MODE (src)) < GET_MODE_SIZE (Pmode))
850 case SIGN_EXTEND: /* used for NT/Alpha pointers */
852 return find_base_value (XEXP (src, 0));
861 /* Called from init_alias_analysis indirectly through note_stores. */
863 /* While scanning insns to find base values, reg_seen[N] is nonzero if
864 register N has been set in this function. */
865 static char *reg_seen;
867 /* Addresses which are known not to alias anything else are identified
868 by a unique integer. */
869 static int unique_id;
872 record_set (dest, set, data)
874 void *data ATTRIBUTE_UNUSED;
879 if (GET_CODE (dest) != REG)
882 regno = REGNO (dest);
884 if (regno >= reg_base_value_size)
889 /* A CLOBBER wipes out any old value but does not prevent a previously
890 unset register from acquiring a base address (i.e. reg_seen is not
892 if (GET_CODE (set) == CLOBBER)
894 new_reg_base_value[regno] = 0;
903 new_reg_base_value[regno] = 0;
907 new_reg_base_value[regno] = gen_rtx_ADDRESS (Pmode,
908 GEN_INT (unique_id++));
912 /* This is not the first set. If the new value is not related to the
913 old value, forget the base value. Note that the following code is
915 extern int x, y; int *p = &x; p += (&y-&x);
916 ANSI C does not allow computing the difference of addresses
917 of distinct top level objects. */
918 if (new_reg_base_value[regno])
919 switch (GET_CODE (src))
923 if (XEXP (src, 0) != dest && XEXP (src, 1) != dest)
924 new_reg_base_value[regno] = 0;
927 /* If the value we add in the PLUS is also a valid base value,
928 this might be the actual base value, and the original value
931 rtx other = NULL_RTX;
933 if (XEXP (src, 0) == dest)
934 other = XEXP (src, 1);
935 else if (XEXP (src, 1) == dest)
936 other = XEXP (src, 0);
938 if (! other || find_base_value (other))
939 new_reg_base_value[regno] = 0;
943 if (XEXP (src, 0) != dest || GET_CODE (XEXP (src, 1)) != CONST_INT)
944 new_reg_base_value[regno] = 0;
947 new_reg_base_value[regno] = 0;
950 /* If this is the first set of a register, record the value. */
951 else if ((regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
952 && ! reg_seen[regno] && new_reg_base_value[regno] == 0)
953 new_reg_base_value[regno] = find_base_value (src);
958 /* Called from loop optimization when a new pseudo-register is
959 created. It indicates that REGNO is being set to VAL. f INVARIANT
960 is true then this value also describes an invariant relationship
961 which can be used to deduce that two registers with unknown values
965 record_base_value (regno, val, invariant)
970 if (regno >= reg_base_value_size)
973 if (invariant && alias_invariant)
974 alias_invariant[regno] = val;
976 if (GET_CODE (val) == REG)
978 if (REGNO (val) < reg_base_value_size)
979 reg_base_value[regno] = reg_base_value[REGNO (val)];
984 reg_base_value[regno] = find_base_value (val);
987 /* Clear alias info for a register. This is used if an RTL transformation
988 changes the value of a register. This is used in flow by AUTO_INC_DEC
989 optimizations. We don't need to clear reg_base_value, since flow only
990 changes the offset. */
993 clear_reg_alias_info (reg)
996 unsigned int regno = REGNO (reg);
998 if (regno < reg_known_value_size && regno >= FIRST_PSEUDO_REGISTER)
999 reg_known_value[regno] = reg;
1002 /* Returns a canonical version of X, from the point of view alias
1003 analysis. (For example, if X is a MEM whose address is a register,
1004 and the register has a known value (say a SYMBOL_REF), then a MEM
1005 whose address is the SYMBOL_REF is returned.) */
1011 /* Recursively look for equivalences. */
1012 if (GET_CODE (x) == REG && REGNO (x) >= FIRST_PSEUDO_REGISTER
1013 && REGNO (x) < reg_known_value_size)
1014 return reg_known_value[REGNO (x)] == x
1015 ? x : canon_rtx (reg_known_value[REGNO (x)]);
1016 else if (GET_CODE (x) == PLUS)
1018 rtx x0 = canon_rtx (XEXP (x, 0));
1019 rtx x1 = canon_rtx (XEXP (x, 1));
1021 if (x0 != XEXP (x, 0) || x1 != XEXP (x, 1))
1023 if (GET_CODE (x0) == CONST_INT)
1024 return plus_constant (x1, INTVAL (x0));
1025 else if (GET_CODE (x1) == CONST_INT)
1026 return plus_constant (x0, INTVAL (x1));
1027 return gen_rtx_PLUS (GET_MODE (x), x0, x1);
1031 /* This gives us much better alias analysis when called from
1032 the loop optimizer. Note we want to leave the original
1033 MEM alone, but need to return the canonicalized MEM with
1034 all the flags with their original values. */
1035 else if (GET_CODE (x) == MEM)
1036 x = replace_equiv_address_nv (x, canon_rtx (XEXP (x, 0)));
1041 /* Return 1 if X and Y are identical-looking rtx's.
1043 We use the data in reg_known_value above to see if two registers with
1044 different numbers are, in fact, equivalent. */
1047 rtx_equal_for_memref_p (x, y)
1055 if (x == 0 && y == 0)
1057 if (x == 0 || y == 0)
1066 code = GET_CODE (x);
1067 /* Rtx's of different codes cannot be equal. */
1068 if (code != GET_CODE (y))
1071 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1072 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1074 if (GET_MODE (x) != GET_MODE (y))
1077 /* Some RTL can be compared without a recursive examination. */
1081 return CSELIB_VAL_PTR (x) == CSELIB_VAL_PTR (y);
1084 return REGNO (x) == REGNO (y);
1087 return XEXP (x, 0) == XEXP (y, 0);
1090 return XSTR (x, 0) == XSTR (y, 0);
1094 /* There's no need to compare the contents of CONST_DOUBLEs or
1095 CONST_INTs because pointer equality is a good enough
1096 comparison for these nodes. */
1100 return (XINT (x, 1) == XINT (y, 1)
1101 && rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0)));
1107 /* For commutative operations, the RTX match if the operand match in any
1108 order. Also handle the simple binary and unary cases without a loop. */
1109 if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')
1110 return ((rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0))
1111 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1)))
1112 || (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 1))
1113 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 0))));
1114 else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2')
1115 return (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0))
1116 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1)));
1117 else if (GET_RTX_CLASS (code) == '1')
1118 return rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0));
1120 /* Compare the elements. If any pair of corresponding elements
1121 fail to match, return 0 for the whole things.
1123 Limit cases to types which actually appear in addresses. */
1125 fmt = GET_RTX_FORMAT (code);
1126 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1131 if (XINT (x, i) != XINT (y, i))
1136 /* Two vectors must have the same length. */
1137 if (XVECLEN (x, i) != XVECLEN (y, i))
1140 /* And the corresponding elements must match. */
1141 for (j = 0; j < XVECLEN (x, i); j++)
1142 if (rtx_equal_for_memref_p (XVECEXP (x, i, j),
1143 XVECEXP (y, i, j)) == 0)
1148 if (rtx_equal_for_memref_p (XEXP (x, i), XEXP (y, i)) == 0)
1152 /* This can happen for asm operands. */
1154 if (strcmp (XSTR (x, i), XSTR (y, i)))
1158 /* This can happen for an asm which clobbers memory. */
1162 /* It is believed that rtx's at this level will never
1163 contain anything but integers and other rtx's,
1164 except for within LABEL_REFs and SYMBOL_REFs. */
1172 /* Given an rtx X, find a SYMBOL_REF or LABEL_REF within
1173 X and return it, or return 0 if none found. */
1176 find_symbolic_term (x)
1183 code = GET_CODE (x);
1184 if (code == SYMBOL_REF || code == LABEL_REF)
1186 if (GET_RTX_CLASS (code) == 'o')
1189 fmt = GET_RTX_FORMAT (code);
1190 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1196 t = find_symbolic_term (XEXP (x, i));
1200 else if (fmt[i] == 'E')
1211 struct elt_loc_list *l;
1213 #if defined (FIND_BASE_TERM)
1214 /* Try machine-dependent ways to find the base term. */
1215 x = FIND_BASE_TERM (x);
1218 switch (GET_CODE (x))
1221 return REG_BASE_VALUE (x);
1224 case SIGN_EXTEND: /* Used for Alpha/NT pointers */
1230 return find_base_term (XEXP (x, 0));
1233 val = CSELIB_VAL_PTR (x);
1234 for (l = val->locs; l; l = l->next)
1235 if ((x = find_base_term (l->loc)) != 0)
1241 if (GET_CODE (x) != PLUS && GET_CODE (x) != MINUS)
1248 rtx tmp1 = XEXP (x, 0);
1249 rtx tmp2 = XEXP (x, 1);
1251 /* This is a little bit tricky since we have to determine which of
1252 the two operands represents the real base address. Otherwise this
1253 routine may return the index register instead of the base register.
1255 That may cause us to believe no aliasing was possible, when in
1256 fact aliasing is possible.
1258 We use a few simple tests to guess the base register. Additional
1259 tests can certainly be added. For example, if one of the operands
1260 is a shift or multiply, then it must be the index register and the
1261 other operand is the base register. */
1263 if (tmp1 == pic_offset_table_rtx && CONSTANT_P (tmp2))
1264 return find_base_term (tmp2);
1266 /* If either operand is known to be a pointer, then use it
1267 to determine the base term. */
1268 if (REG_P (tmp1) && REG_POINTER (tmp1))
1269 return find_base_term (tmp1);
1271 if (REG_P (tmp2) && REG_POINTER (tmp2))
1272 return find_base_term (tmp2);
1274 /* Neither operand was known to be a pointer. Go ahead and find the
1275 base term for both operands. */
1276 tmp1 = find_base_term (tmp1);
1277 tmp2 = find_base_term (tmp2);
1279 /* If either base term is named object or a special address
1280 (like an argument or stack reference), then use it for the
1283 && (GET_CODE (tmp1) == SYMBOL_REF
1284 || GET_CODE (tmp1) == LABEL_REF
1285 || (GET_CODE (tmp1) == ADDRESS
1286 && GET_MODE (tmp1) != VOIDmode)))
1290 && (GET_CODE (tmp2) == SYMBOL_REF
1291 || GET_CODE (tmp2) == LABEL_REF
1292 || (GET_CODE (tmp2) == ADDRESS
1293 && GET_MODE (tmp2) != VOIDmode)))
1296 /* We could not determine which of the two operands was the
1297 base register and which was the index. So we can determine
1298 nothing from the base alias check. */
1303 if (GET_CODE (XEXP (x, 0)) == REG && GET_CODE (XEXP (x, 1)) == CONST_INT)
1304 return REG_BASE_VALUE (XEXP (x, 0));
1312 return REG_BASE_VALUE (frame_pointer_rtx);
1319 /* Return 0 if the addresses X and Y are known to point to different
1320 objects, 1 if they might be pointers to the same object. */
1323 base_alias_check (x, y, x_mode, y_mode)
1325 enum machine_mode x_mode, y_mode;
1327 rtx x_base = find_base_term (x);
1328 rtx y_base = find_base_term (y);
1330 /* If the address itself has no known base see if a known equivalent
1331 value has one. If either address still has no known base, nothing
1332 is known about aliasing. */
1337 if (! flag_expensive_optimizations || (x_c = canon_rtx (x)) == x)
1340 x_base = find_base_term (x_c);
1348 if (! flag_expensive_optimizations || (y_c = canon_rtx (y)) == y)
1351 y_base = find_base_term (y_c);
1356 /* If the base addresses are equal nothing is known about aliasing. */
1357 if (rtx_equal_p (x_base, y_base))
1360 /* The base addresses of the read and write are different expressions.
1361 If they are both symbols and they are not accessed via AND, there is
1362 no conflict. We can bring knowledge of object alignment into play
1363 here. For example, on alpha, "char a, b;" can alias one another,
1364 though "char a; long b;" cannot. */
1365 if (GET_CODE (x_base) != ADDRESS && GET_CODE (y_base) != ADDRESS)
1367 if (GET_CODE (x) == AND && GET_CODE (y) == AND)
1369 if (GET_CODE (x) == AND
1370 && (GET_CODE (XEXP (x, 1)) != CONST_INT
1371 || (int) GET_MODE_UNIT_SIZE (y_mode) < -INTVAL (XEXP (x, 1))))
1373 if (GET_CODE (y) == AND
1374 && (GET_CODE (XEXP (y, 1)) != CONST_INT
1375 || (int) GET_MODE_UNIT_SIZE (x_mode) < -INTVAL (XEXP (y, 1))))
1377 /* Differing symbols never alias. */
1381 /* If one address is a stack reference there can be no alias:
1382 stack references using different base registers do not alias,
1383 a stack reference can not alias a parameter, and a stack reference
1384 can not alias a global. */
1385 if ((GET_CODE (x_base) == ADDRESS && GET_MODE (x_base) == Pmode)
1386 || (GET_CODE (y_base) == ADDRESS && GET_MODE (y_base) == Pmode))
1389 if (! flag_argument_noalias)
1392 if (flag_argument_noalias > 1)
1395 /* Weak noalias assertion (arguments are distinct, but may match globals). */
1396 return ! (GET_MODE (x_base) == VOIDmode && GET_MODE (y_base) == VOIDmode);
1399 /* Convert the address X into something we can use. This is done by returning
1400 it unchanged unless it is a value; in the latter case we call cselib to get
1401 a more useful rtx. */
1408 struct elt_loc_list *l;
1410 if (GET_CODE (x) != VALUE)
1412 v = CSELIB_VAL_PTR (x);
1413 for (l = v->locs; l; l = l->next)
1414 if (CONSTANT_P (l->loc))
1416 for (l = v->locs; l; l = l->next)
1417 if (GET_CODE (l->loc) != REG && GET_CODE (l->loc) != MEM)
1420 return v->locs->loc;
1424 /* Return the address of the (N_REFS + 1)th memory reference to ADDR
1425 where SIZE is the size in bytes of the memory reference. If ADDR
1426 is not modified by the memory reference then ADDR is returned. */
1429 addr_side_effect_eval (addr, size, n_refs)
1436 switch (GET_CODE (addr))
1439 offset = (n_refs + 1) * size;
1442 offset = -(n_refs + 1) * size;
1445 offset = n_refs * size;
1448 offset = -n_refs * size;
1456 addr = gen_rtx_PLUS (GET_MODE (addr), XEXP (addr, 0), GEN_INT (offset));
1458 addr = XEXP (addr, 0);
1463 /* Return nonzero if X and Y (memory addresses) could reference the
1464 same location in memory. C is an offset accumulator. When
1465 C is nonzero, we are testing aliases between X and Y + C.
1466 XSIZE is the size in bytes of the X reference,
1467 similarly YSIZE is the size in bytes for Y.
1469 If XSIZE or YSIZE is zero, we do not know the amount of memory being
1470 referenced (the reference was BLKmode), so make the most pessimistic
1473 If XSIZE or YSIZE is negative, we may access memory outside the object
1474 being referenced as a side effect. This can happen when using AND to
1475 align memory references, as is done on the Alpha.
1477 Nice to notice that varying addresses cannot conflict with fp if no
1478 local variables had their addresses taken, but that's too hard now. */
1481 memrefs_conflict_p (xsize, x, ysize, y, c)
1486 if (GET_CODE (x) == VALUE)
1488 if (GET_CODE (y) == VALUE)
1490 if (GET_CODE (x) == HIGH)
1492 else if (GET_CODE (x) == LO_SUM)
1495 x = canon_rtx (addr_side_effect_eval (x, xsize, 0));
1496 if (GET_CODE (y) == HIGH)
1498 else if (GET_CODE (y) == LO_SUM)
1501 y = canon_rtx (addr_side_effect_eval (y, ysize, 0));
1503 if (rtx_equal_for_memref_p (x, y))
1505 if (xsize <= 0 || ysize <= 0)
1507 if (c >= 0 && xsize > c)
1509 if (c < 0 && ysize+c > 0)
1514 /* This code used to check for conflicts involving stack references and
1515 globals but the base address alias code now handles these cases. */
1517 if (GET_CODE (x) == PLUS)
1519 /* The fact that X is canonicalized means that this
1520 PLUS rtx is canonicalized. */
1521 rtx x0 = XEXP (x, 0);
1522 rtx x1 = XEXP (x, 1);
1524 if (GET_CODE (y) == PLUS)
1526 /* The fact that Y is canonicalized means that this
1527 PLUS rtx is canonicalized. */
1528 rtx y0 = XEXP (y, 0);
1529 rtx y1 = XEXP (y, 1);
1531 if (rtx_equal_for_memref_p (x1, y1))
1532 return memrefs_conflict_p (xsize, x0, ysize, y0, c);
1533 if (rtx_equal_for_memref_p (x0, y0))
1534 return memrefs_conflict_p (xsize, x1, ysize, y1, c);
1535 if (GET_CODE (x1) == CONST_INT)
1537 if (GET_CODE (y1) == CONST_INT)
1538 return memrefs_conflict_p (xsize, x0, ysize, y0,
1539 c - INTVAL (x1) + INTVAL (y1));
1541 return memrefs_conflict_p (xsize, x0, ysize, y,
1544 else if (GET_CODE (y1) == CONST_INT)
1545 return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
1549 else if (GET_CODE (x1) == CONST_INT)
1550 return memrefs_conflict_p (xsize, x0, ysize, y, c - INTVAL (x1));
1552 else if (GET_CODE (y) == PLUS)
1554 /* The fact that Y is canonicalized means that this
1555 PLUS rtx is canonicalized. */
1556 rtx y0 = XEXP (y, 0);
1557 rtx y1 = XEXP (y, 1);
1559 if (GET_CODE (y1) == CONST_INT)
1560 return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1));
1565 if (GET_CODE (x) == GET_CODE (y))
1566 switch (GET_CODE (x))
1570 /* Handle cases where we expect the second operands to be the
1571 same, and check only whether the first operand would conflict
1574 rtx x1 = canon_rtx (XEXP (x, 1));
1575 rtx y1 = canon_rtx (XEXP (y, 1));
1576 if (! rtx_equal_for_memref_p (x1, y1))
1578 x0 = canon_rtx (XEXP (x, 0));
1579 y0 = canon_rtx (XEXP (y, 0));
1580 if (rtx_equal_for_memref_p (x0, y0))
1581 return (xsize == 0 || ysize == 0
1582 || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
1584 /* Can't properly adjust our sizes. */
1585 if (GET_CODE (x1) != CONST_INT)
1587 xsize /= INTVAL (x1);
1588 ysize /= INTVAL (x1);
1590 return memrefs_conflict_p (xsize, x0, ysize, y0, c);
1594 /* Are these registers known not to be equal? */
1595 if (alias_invariant)
1597 unsigned int r_x = REGNO (x), r_y = REGNO (y);
1598 rtx i_x, i_y; /* invariant relationships of X and Y */
1600 i_x = r_x >= reg_base_value_size ? 0 : alias_invariant[r_x];
1601 i_y = r_y >= reg_base_value_size ? 0 : alias_invariant[r_y];
1603 if (i_x == 0 && i_y == 0)
1606 if (! memrefs_conflict_p (xsize, i_x ? i_x : x,
1607 ysize, i_y ? i_y : y, c))
1616 /* Treat an access through an AND (e.g. a subword access on an Alpha)
1617 as an access with indeterminate size. Assume that references
1618 besides AND are aligned, so if the size of the other reference is
1619 at least as large as the alignment, assume no other overlap. */
1620 if (GET_CODE (x) == AND && GET_CODE (XEXP (x, 1)) == CONST_INT)
1622 if (GET_CODE (y) == AND || ysize < -INTVAL (XEXP (x, 1)))
1624 return memrefs_conflict_p (xsize, XEXP (x, 0), ysize, y, c);
1626 if (GET_CODE (y) == AND && GET_CODE (XEXP (y, 1)) == CONST_INT)
1628 /* ??? If we are indexing far enough into the array/structure, we
1629 may yet be able to determine that we can not overlap. But we
1630 also need to that we are far enough from the end not to overlap
1631 a following reference, so we do nothing with that for now. */
1632 if (GET_CODE (x) == AND || xsize < -INTVAL (XEXP (y, 1)))
1634 return memrefs_conflict_p (xsize, x, ysize, XEXP (y, 0), c);
1637 if (GET_CODE (x) == ADDRESSOF)
1639 if (y == frame_pointer_rtx
1640 || GET_CODE (y) == ADDRESSOF)
1641 return xsize <= 0 || ysize <= 0;
1643 if (GET_CODE (y) == ADDRESSOF)
1645 if (x == frame_pointer_rtx)
1646 return xsize <= 0 || ysize <= 0;
1651 if (GET_CODE (x) == CONST_INT && GET_CODE (y) == CONST_INT)
1653 c += (INTVAL (y) - INTVAL (x));
1654 return (xsize <= 0 || ysize <= 0
1655 || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
1658 if (GET_CODE (x) == CONST)
1660 if (GET_CODE (y) == CONST)
1661 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
1662 ysize, canon_rtx (XEXP (y, 0)), c);
1664 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
1667 if (GET_CODE (y) == CONST)
1668 return memrefs_conflict_p (xsize, x, ysize,
1669 canon_rtx (XEXP (y, 0)), c);
1672 return (xsize <= 0 || ysize <= 0
1673 || (rtx_equal_for_memref_p (x, y)
1674 && ((c >= 0 && xsize > c) || (c < 0 && ysize+c > 0))));
1681 /* Functions to compute memory dependencies.
1683 Since we process the insns in execution order, we can build tables
1684 to keep track of what registers are fixed (and not aliased), what registers
1685 are varying in known ways, and what registers are varying in unknown
1688 If both memory references are volatile, then there must always be a
1689 dependence between the two references, since their order can not be
1690 changed. A volatile and non-volatile reference can be interchanged
1693 A MEM_IN_STRUCT reference at a non-AND varying address can never
1694 conflict with a non-MEM_IN_STRUCT reference at a fixed address. We
1695 also must allow AND addresses, because they may generate accesses
1696 outside the object being referenced. This is used to generate
1697 aligned addresses from unaligned addresses, for instance, the alpha
1698 storeqi_unaligned pattern. */
1700 /* Read dependence: X is read after read in MEM takes place. There can
1701 only be a dependence here if both reads are volatile. */
1704 read_dependence (mem, x)
1708 return MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem);
1711 /* Returns MEM1 if and only if MEM1 is a scalar at a fixed address and
1712 MEM2 is a reference to a structure at a varying address, or returns
1713 MEM2 if vice versa. Otherwise, returns NULL_RTX. If a non-NULL
1714 value is returned MEM1 and MEM2 can never alias. VARIES_P is used
1715 to decide whether or not an address may vary; it should return
1716 nonzero whenever variation is possible.
1717 MEM1_ADDR and MEM2_ADDR are the addresses of MEM1 and MEM2. */
1720 fixed_scalar_and_varying_struct_p (mem1, mem2, mem1_addr, mem2_addr, varies_p)
1722 rtx mem1_addr, mem2_addr;
1723 int (*varies_p) PARAMS ((rtx, int));
1725 if (! flag_strict_aliasing)
1728 if (MEM_SCALAR_P (mem1) && MEM_IN_STRUCT_P (mem2)
1729 && !varies_p (mem1_addr, 1) && varies_p (mem2_addr, 1))
1730 /* MEM1 is a scalar at a fixed address; MEM2 is a struct at a
1734 if (MEM_IN_STRUCT_P (mem1) && MEM_SCALAR_P (mem2)
1735 && varies_p (mem1_addr, 1) && !varies_p (mem2_addr, 1))
1736 /* MEM2 is a scalar at a fixed address; MEM1 is a struct at a
1743 /* Returns nonzero if something about the mode or address format MEM1
1744 indicates that it might well alias *anything*. */
1747 aliases_everything_p (mem)
1750 if (GET_CODE (XEXP (mem, 0)) == AND)
1751 /* If the address is an AND, its very hard to know at what it is
1752 actually pointing. */
1758 /* Return true if we can determine that the fields referenced cannot
1759 overlap for any pair of objects. */
1762 nonoverlapping_component_refs_p (x, y)
1765 tree fieldx, fieldy, typex, typey, orig_y;
1769 /* The comparison has to be done at a common type, since we don't
1770 know how the inheritance hierarchy works. */
1774 fieldx = TREE_OPERAND (x, 1);
1775 typex = DECL_FIELD_CONTEXT (fieldx);
1780 fieldy = TREE_OPERAND (y, 1);
1781 typey = DECL_FIELD_CONTEXT (fieldy);
1786 y = TREE_OPERAND (y, 0);
1788 while (y && TREE_CODE (y) == COMPONENT_REF);
1790 x = TREE_OPERAND (x, 0);
1792 while (x && TREE_CODE (x) == COMPONENT_REF);
1794 /* Never found a common type. */
1798 /* If we're left with accessing different fields of a structure,
1800 if (TREE_CODE (typex) == RECORD_TYPE
1801 && fieldx != fieldy)
1804 /* The comparison on the current field failed. If we're accessing
1805 a very nested structure, look at the next outer level. */
1806 x = TREE_OPERAND (x, 0);
1807 y = TREE_OPERAND (y, 0);
1810 && TREE_CODE (x) == COMPONENT_REF
1811 && TREE_CODE (y) == COMPONENT_REF);
1816 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */
1819 decl_for_component_ref (x)
1824 x = TREE_OPERAND (x, 0);
1826 while (x && TREE_CODE (x) == COMPONENT_REF);
1828 return x && DECL_P (x) ? x : NULL_TREE;
1831 /* Walk up the COMPONENT_REF list and adjust OFFSET to compensate for the
1832 offset of the field reference. */
1835 adjust_offset_for_component_ref (x, offset)
1839 HOST_WIDE_INT ioffset;
1844 ioffset = INTVAL (offset);
1847 tree field = TREE_OPERAND (x, 1);
1849 if (! host_integerp (DECL_FIELD_OFFSET (field), 1))
1851 ioffset += (tree_low_cst (DECL_FIELD_OFFSET (field), 1)
1852 + (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1)
1855 x = TREE_OPERAND (x, 0);
1857 while (x && TREE_CODE (x) == COMPONENT_REF);
1859 return GEN_INT (ioffset);
1862 /* Return nonzero if we can deterimine the exprs corresponding to memrefs
1863 X and Y and they do not overlap. */
1866 nonoverlapping_memrefs_p (x, y)
1869 tree exprx = MEM_EXPR (x), expry = MEM_EXPR (y);
1872 rtx moffsetx, moffsety;
1873 HOST_WIDE_INT offsetx = 0, offsety = 0, sizex, sizey, tem;
1875 /* Unless both have exprs, we can't tell anything. */
1876 if (exprx == 0 || expry == 0)
1879 /* If both are field references, we may be able to determine something. */
1880 if (TREE_CODE (exprx) == COMPONENT_REF
1881 && TREE_CODE (expry) == COMPONENT_REF
1882 && nonoverlapping_component_refs_p (exprx, expry))
1885 /* If the field reference test failed, look at the DECLs involved. */
1886 moffsetx = MEM_OFFSET (x);
1887 if (TREE_CODE (exprx) == COMPONENT_REF)
1889 tree t = decl_for_component_ref (exprx);
1892 moffsetx = adjust_offset_for_component_ref (exprx, moffsetx);
1895 moffsety = MEM_OFFSET (y);
1896 if (TREE_CODE (expry) == COMPONENT_REF)
1898 tree t = decl_for_component_ref (expry);
1901 moffsety = adjust_offset_for_component_ref (expry, moffsety);
1905 if (! DECL_P (exprx) || ! DECL_P (expry))
1908 rtlx = DECL_RTL (exprx);
1909 rtly = DECL_RTL (expry);
1911 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they
1912 can't overlap unless they are the same because we never reuse that part
1913 of the stack frame used for locals for spilled pseudos. */
1914 if ((GET_CODE (rtlx) != MEM || GET_CODE (rtly) != MEM)
1915 && ! rtx_equal_p (rtlx, rtly))
1918 /* Get the base and offsets of both decls. If either is a register, we
1919 know both are and are the same, so use that as the base. The only
1920 we can avoid overlap is if we can deduce that they are nonoverlapping
1921 pieces of that decl, which is very rare. */
1922 basex = GET_CODE (rtlx) == MEM ? XEXP (rtlx, 0) : rtlx;
1923 if (GET_CODE (basex) == PLUS && GET_CODE (XEXP (basex, 1)) == CONST_INT)
1924 offsetx = INTVAL (XEXP (basex, 1)), basex = XEXP (basex, 0);
1926 basey = GET_CODE (rtly) == MEM ? XEXP (rtly, 0) : rtly;
1927 if (GET_CODE (basey) == PLUS && GET_CODE (XEXP (basey, 1)) == CONST_INT)
1928 offsety = INTVAL (XEXP (basey, 1)), basey = XEXP (basey, 0);
1930 /* If the bases are different, we know they do not overlap if both
1931 are constants or if one is a constant and the other a pointer into the
1932 stack frame. Otherwise a different base means we can't tell if they
1934 if (! rtx_equal_p (basex, basey))
1935 return ((CONSTANT_P (basex) && CONSTANT_P (basey))
1936 || (CONSTANT_P (basex) && REG_P (basey)
1937 && REGNO_PTR_FRAME_P (REGNO (basey)))
1938 || (CONSTANT_P (basey) && REG_P (basex)
1939 && REGNO_PTR_FRAME_P (REGNO (basex))));
1941 sizex = (GET_CODE (rtlx) != MEM ? (int) GET_MODE_SIZE (GET_MODE (rtlx))
1942 : MEM_SIZE (rtlx) ? INTVAL (MEM_SIZE (rtlx))
1944 sizey = (GET_CODE (rtly) != MEM ? (int) GET_MODE_SIZE (GET_MODE (rtly))
1945 : MEM_SIZE (rtly) ? INTVAL (MEM_SIZE (rtly)) :
1948 /* If we have an offset for either memref, it can update the values computed
1951 offsetx += INTVAL (moffsetx), sizex -= INTVAL (moffsetx);
1953 offsety += INTVAL (moffsety), sizey -= INTVAL (moffsety);
1955 /* If a memref has both a size and an offset, we can use the smaller size.
1956 We can't do this if the offset isn't known because we must view this
1957 memref as being anywhere inside the DECL's MEM. */
1958 if (MEM_SIZE (x) && moffsetx)
1959 sizex = INTVAL (MEM_SIZE (x));
1960 if (MEM_SIZE (y) && moffsety)
1961 sizey = INTVAL (MEM_SIZE (y));
1963 /* Put the values of the memref with the lower offset in X's values. */
1964 if (offsetx > offsety)
1966 tem = offsetx, offsetx = offsety, offsety = tem;
1967 tem = sizex, sizex = sizey, sizey = tem;
1970 /* If we don't know the size of the lower-offset value, we can't tell
1971 if they conflict. Otherwise, we do the test. */
1972 return sizex >= 0 && offsety > offsetx + sizex;
1975 /* True dependence: X is read after store in MEM takes place. */
1978 true_dependence (mem, mem_mode, x, varies)
1980 enum machine_mode mem_mode;
1982 int (*varies) PARAMS ((rtx, int));
1984 rtx x_addr, mem_addr;
1987 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
1990 if (DIFFERENT_ALIAS_SETS_P (x, mem))
1993 /* Unchanging memory can't conflict with non-unchanging memory.
1994 A non-unchanging read can conflict with a non-unchanging write.
1995 An unchanging read can conflict with an unchanging write since
1996 there may be a single store to this address to initialize it.
1997 Note that an unchanging store can conflict with a non-unchanging read
1998 since we have to make conservative assumptions when we have a
1999 record with readonly fields and we are copying the whole thing.
2000 Just fall through to the code below to resolve potential conflicts.
2001 This won't handle all cases optimally, but the possible performance
2002 loss should be negligible. */
2003 if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem))
2006 if (nonoverlapping_memrefs_p (mem, x))
2009 if (mem_mode == VOIDmode)
2010 mem_mode = GET_MODE (mem);
2012 x_addr = get_addr (XEXP (x, 0));
2013 mem_addr = get_addr (XEXP (mem, 0));
2015 base = find_base_term (x_addr);
2016 if (base && (GET_CODE (base) == LABEL_REF
2017 || (GET_CODE (base) == SYMBOL_REF
2018 && CONSTANT_POOL_ADDRESS_P (base))))
2021 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode))
2024 x_addr = canon_rtx (x_addr);
2025 mem_addr = canon_rtx (mem_addr);
2027 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
2028 SIZE_FOR_MODE (x), x_addr, 0))
2031 if (aliases_everything_p (x))
2034 /* We cannot use aliases_everything_p to test MEM, since we must look
2035 at MEM_MODE, rather than GET_MODE (MEM). */
2036 if (mem_mode == QImode || GET_CODE (mem_addr) == AND)
2039 /* In true_dependence we also allow BLKmode to alias anything. Why
2040 don't we do this in anti_dependence and output_dependence? */
2041 if (mem_mode == BLKmode || GET_MODE (x) == BLKmode)
2044 return ! fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr,
2048 /* Canonical true dependence: X is read after store in MEM takes place.
2049 Variant of true_dependence which assumes MEM has already been
2050 canonicalized (hence we no longer do that here).
2051 The mem_addr argument has been added, since true_dependence computed
2052 this value prior to canonicalizing. */
2055 canon_true_dependence (mem, mem_mode, mem_addr, x, varies)
2056 rtx mem, mem_addr, x;
2057 enum machine_mode mem_mode;
2058 int (*varies) PARAMS ((rtx, int));
2062 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2065 if (DIFFERENT_ALIAS_SETS_P (x, mem))
2068 /* If X is an unchanging read, then it can't possibly conflict with any
2069 non-unchanging store. It may conflict with an unchanging write though,
2070 because there may be a single store to this address to initialize it.
2071 Just fall through to the code below to resolve the case where we have
2072 both an unchanging read and an unchanging write. This won't handle all
2073 cases optimally, but the possible performance loss should be
2075 if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem))
2078 if (nonoverlapping_memrefs_p (x, mem))
2081 x_addr = get_addr (XEXP (x, 0));
2083 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode))
2086 x_addr = canon_rtx (x_addr);
2087 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
2088 SIZE_FOR_MODE (x), x_addr, 0))
2091 if (aliases_everything_p (x))
2094 /* We cannot use aliases_everything_p to test MEM, since we must look
2095 at MEM_MODE, rather than GET_MODE (MEM). */
2096 if (mem_mode == QImode || GET_CODE (mem_addr) == AND)
2099 /* In true_dependence we also allow BLKmode to alias anything. Why
2100 don't we do this in anti_dependence and output_dependence? */
2101 if (mem_mode == BLKmode || GET_MODE (x) == BLKmode)
2104 return ! fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr,
2108 /* Returns non-zero if a write to X might alias a previous read from
2109 (or, if WRITEP is non-zero, a write to) MEM. */
2112 write_dependence_p (mem, x, writep)
2117 rtx x_addr, mem_addr;
2121 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
2124 if (DIFFERENT_ALIAS_SETS_P (x, mem))
2127 /* Unchanging memory can't conflict with non-unchanging memory. */
2128 if (RTX_UNCHANGING_P (x) != RTX_UNCHANGING_P (mem))
2131 /* If MEM is an unchanging read, then it can't possibly conflict with
2132 the store to X, because there is at most one store to MEM, and it must
2133 have occurred somewhere before MEM. */
2134 if (! writep && RTX_UNCHANGING_P (mem))
2137 if (nonoverlapping_memrefs_p (x, mem))
2140 x_addr = get_addr (XEXP (x, 0));
2141 mem_addr = get_addr (XEXP (mem, 0));
2145 base = find_base_term (mem_addr);
2146 if (base && (GET_CODE (base) == LABEL_REF
2147 || (GET_CODE (base) == SYMBOL_REF
2148 && CONSTANT_POOL_ADDRESS_P (base))))
2152 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x),
2156 x_addr = canon_rtx (x_addr);
2157 mem_addr = canon_rtx (mem_addr);
2159 if (!memrefs_conflict_p (SIZE_FOR_MODE (mem), mem_addr,
2160 SIZE_FOR_MODE (x), x_addr, 0))
2164 = fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr,
2167 return (!(fixed_scalar == mem && !aliases_everything_p (x))
2168 && !(fixed_scalar == x && !aliases_everything_p (mem)));
2171 /* Anti dependence: X is written after read in MEM takes place. */
2174 anti_dependence (mem, x)
2178 return write_dependence_p (mem, x, /*writep=*/0);
2181 /* Output dependence: X is written after store in MEM takes place. */
2184 output_dependence (mem, x)
2188 return write_dependence_p (mem, x, /*writep=*/1);
2191 /* Returns non-zero if X mentions something which is not
2192 local to the function and is not constant. */
2195 nonlocal_mentioned_p (x)
2202 code = GET_CODE (x);
2204 if (GET_RTX_CLASS (code) == 'i')
2206 /* Constant functions can be constant if they don't use
2207 scratch memory used to mark function w/o side effects. */
2208 if (code == CALL_INSN && CONST_OR_PURE_CALL_P (x))
2210 x = CALL_INSN_FUNCTION_USAGE (x);
2216 code = GET_CODE (x);
2222 if (GET_CODE (SUBREG_REG (x)) == REG)
2224 /* Global registers are not local. */
2225 if (REGNO (SUBREG_REG (x)) < FIRST_PSEUDO_REGISTER
2226 && global_regs[subreg_regno (x)])
2234 /* Global registers are not local. */
2235 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2249 /* Constants in the function's constants pool are constant. */
2250 if (CONSTANT_POOL_ADDRESS_P (x))
2255 /* Non-constant calls and recursion are not local. */
2259 /* Be overly conservative and consider any volatile memory
2260 reference as not local. */
2261 if (MEM_VOLATILE_P (x))
2263 base = find_base_term (XEXP (x, 0));
2266 /* A Pmode ADDRESS could be a reference via the structure value
2267 address or static chain. Such memory references are nonlocal.
2269 Thus, we have to examine the contents of the ADDRESS to find
2270 out if this is a local reference or not. */
2271 if (GET_CODE (base) == ADDRESS
2272 && GET_MODE (base) == Pmode
2273 && (XEXP (base, 0) == stack_pointer_rtx
2274 || XEXP (base, 0) == arg_pointer_rtx
2275 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2276 || XEXP (base, 0) == hard_frame_pointer_rtx
2278 || XEXP (base, 0) == frame_pointer_rtx))
2280 /* Constants in the function's constant pool are constant. */
2281 if (GET_CODE (base) == SYMBOL_REF && CONSTANT_POOL_ADDRESS_P (base))
2286 case UNSPEC_VOLATILE:
2291 if (MEM_VOLATILE_P (x))
2300 /* Recursively scan the operands of this expression. */
2303 const char *fmt = GET_RTX_FORMAT (code);
2306 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2308 if (fmt[i] == 'e' && XEXP (x, i))
2310 if (nonlocal_mentioned_p (XEXP (x, i)))
2313 else if (fmt[i] == 'E')
2316 for (j = 0; j < XVECLEN (x, i); j++)
2317 if (nonlocal_mentioned_p (XVECEXP (x, i, j)))
2326 /* Mark the function if it is constant. */
2329 mark_constant_function ()
2332 int nonlocal_mentioned;
2334 if (TREE_PUBLIC (current_function_decl)
2335 || TREE_READONLY (current_function_decl)
2336 || DECL_IS_PURE (current_function_decl)
2337 || TREE_THIS_VOLATILE (current_function_decl)
2338 || TYPE_MODE (TREE_TYPE (current_function_decl)) == VOIDmode)
2341 /* A loop might not return which counts as a side effect. */
2342 if (mark_dfs_back_edges ())
2345 nonlocal_mentioned = 0;
2347 init_alias_analysis ();
2349 /* Determine if this is a constant function. */
2351 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2352 if (INSN_P (insn) && nonlocal_mentioned_p (insn))
2354 nonlocal_mentioned = 1;
2358 end_alias_analysis ();
2360 /* Mark the function. */
2362 if (! nonlocal_mentioned)
2363 TREE_READONLY (current_function_decl) = 1;
2367 static HARD_REG_SET argument_registers;
2374 #ifndef OUTGOING_REGNO
2375 #define OUTGOING_REGNO(N) N
2377 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2378 /* Check whether this register can hold an incoming pointer
2379 argument. FUNCTION_ARG_REGNO_P tests outgoing register
2380 numbers, so translate if necessary due to register windows. */
2381 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i))
2382 && HARD_REGNO_MODE_OK (i, Pmode))
2383 SET_HARD_REG_BIT (argument_registers, i);
2385 alias_sets = splay_tree_new (splay_tree_compare_ints, 0, 0);
2388 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE
2392 init_alias_analysis ()
2394 int maxreg = max_reg_num ();
2400 reg_known_value_size = maxreg;
2403 = (rtx *) xcalloc ((maxreg - FIRST_PSEUDO_REGISTER), sizeof (rtx))
2404 - FIRST_PSEUDO_REGISTER;
2406 = (char*) xcalloc ((maxreg - FIRST_PSEUDO_REGISTER), sizeof (char))
2407 - FIRST_PSEUDO_REGISTER;
2409 /* Overallocate reg_base_value to allow some growth during loop
2410 optimization. Loop unrolling can create a large number of
2412 reg_base_value_size = maxreg * 2;
2413 reg_base_value = (rtx *) xcalloc (reg_base_value_size, sizeof (rtx));
2414 ggc_add_rtx_root (reg_base_value, reg_base_value_size);
2416 new_reg_base_value = (rtx *) xmalloc (reg_base_value_size * sizeof (rtx));
2417 reg_seen = (char *) xmalloc (reg_base_value_size);
2418 if (! reload_completed && flag_unroll_loops)
2420 /* ??? Why are we realloc'ing if we're just going to zero it? */
2421 alias_invariant = (rtx *)xrealloc (alias_invariant,
2422 reg_base_value_size * sizeof (rtx));
2423 memset ((char *)alias_invariant, 0, reg_base_value_size * sizeof (rtx));
2426 /* The basic idea is that each pass through this loop will use the
2427 "constant" information from the previous pass to propagate alias
2428 information through another level of assignments.
2430 This could get expensive if the assignment chains are long. Maybe
2431 we should throttle the number of iterations, possibly based on
2432 the optimization level or flag_expensive_optimizations.
2434 We could propagate more information in the first pass by making use
2435 of REG_N_SETS to determine immediately that the alias information
2436 for a pseudo is "constant".
2438 A program with an uninitialized variable can cause an infinite loop
2439 here. Instead of doing a full dataflow analysis to detect such problems
2440 we just cap the number of iterations for the loop.
2442 The state of the arrays for the set chain in question does not matter
2443 since the program has undefined behavior. */
2448 /* Assume nothing will change this iteration of the loop. */
2451 /* We want to assign the same IDs each iteration of this loop, so
2452 start counting from zero each iteration of the loop. */
2455 /* We're at the start of the function each iteration through the
2456 loop, so we're copying arguments. */
2457 copying_arguments = 1;
2459 /* Wipe the potential alias information clean for this pass. */
2460 memset ((char *) new_reg_base_value, 0, reg_base_value_size * sizeof (rtx));
2462 /* Wipe the reg_seen array clean. */
2463 memset ((char *) reg_seen, 0, reg_base_value_size);
2465 /* Mark all hard registers which may contain an address.
2466 The stack, frame and argument pointers may contain an address.
2467 An argument register which can hold a Pmode value may contain
2468 an address even if it is not in BASE_REGS.
2470 The address expression is VOIDmode for an argument and
2471 Pmode for other registers. */
2473 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2474 if (TEST_HARD_REG_BIT (argument_registers, i))
2475 new_reg_base_value[i] = gen_rtx_ADDRESS (VOIDmode,
2476 gen_rtx_REG (Pmode, i));
2478 new_reg_base_value[STACK_POINTER_REGNUM]
2479 = gen_rtx_ADDRESS (Pmode, stack_pointer_rtx);
2480 new_reg_base_value[ARG_POINTER_REGNUM]
2481 = gen_rtx_ADDRESS (Pmode, arg_pointer_rtx);
2482 new_reg_base_value[FRAME_POINTER_REGNUM]
2483 = gen_rtx_ADDRESS (Pmode, frame_pointer_rtx);
2484 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
2485 new_reg_base_value[HARD_FRAME_POINTER_REGNUM]
2486 = gen_rtx_ADDRESS (Pmode, hard_frame_pointer_rtx);
2489 /* Walk the insns adding values to the new_reg_base_value array. */
2490 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2496 #if defined (HAVE_prologue) || defined (HAVE_epilogue)
2497 /* The prologue/epilogue insns are not threaded onto the
2498 insn chain until after reload has completed. Thus,
2499 there is no sense wasting time checking if INSN is in
2500 the prologue/epilogue until after reload has completed. */
2501 if (reload_completed
2502 && prologue_epilogue_contains (insn))
2506 /* If this insn has a noalias note, process it, Otherwise,
2507 scan for sets. A simple set will have no side effects
2508 which could change the base value of any other register. */
2510 if (GET_CODE (PATTERN (insn)) == SET
2511 && REG_NOTES (insn) != 0
2512 && find_reg_note (insn, REG_NOALIAS, NULL_RTX))
2513 record_set (SET_DEST (PATTERN (insn)), NULL_RTX, NULL);
2515 note_stores (PATTERN (insn), record_set, NULL);
2517 set = single_set (insn);
2520 && GET_CODE (SET_DEST (set)) == REG
2521 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER)
2523 unsigned int regno = REGNO (SET_DEST (set));
2524 rtx src = SET_SRC (set);
2526 if (REG_NOTES (insn) != 0
2527 && (((note = find_reg_note (insn, REG_EQUAL, 0)) != 0
2528 && REG_N_SETS (regno) == 1)
2529 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) != 0)
2530 && GET_CODE (XEXP (note, 0)) != EXPR_LIST
2531 && ! rtx_varies_p (XEXP (note, 0), 1)
2532 && ! reg_overlap_mentioned_p (SET_DEST (set), XEXP (note, 0)))
2534 reg_known_value[regno] = XEXP (note, 0);
2535 reg_known_equiv_p[regno] = REG_NOTE_KIND (note) == REG_EQUIV;
2537 else if (REG_N_SETS (regno) == 1
2538 && GET_CODE (src) == PLUS
2539 && GET_CODE (XEXP (src, 0)) == REG
2540 && REGNO (XEXP (src, 0)) >= FIRST_PSEUDO_REGISTER
2541 && (reg_known_value[REGNO (XEXP (src, 0))])
2542 && GET_CODE (XEXP (src, 1)) == CONST_INT)
2544 rtx op0 = XEXP (src, 0);
2545 op0 = reg_known_value[REGNO (op0)];
2546 reg_known_value[regno]
2547 = plus_constant (op0, INTVAL (XEXP (src, 1)));
2548 reg_known_equiv_p[regno] = 0;
2550 else if (REG_N_SETS (regno) == 1
2551 && ! rtx_varies_p (src, 1))
2553 reg_known_value[regno] = src;
2554 reg_known_equiv_p[regno] = 0;
2558 else if (GET_CODE (insn) == NOTE
2559 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_BEG)
2560 copying_arguments = 0;
2563 /* Now propagate values from new_reg_base_value to reg_base_value. */
2564 for (ui = 0; ui < reg_base_value_size; ui++)
2566 if (new_reg_base_value[ui]
2567 && new_reg_base_value[ui] != reg_base_value[ui]
2568 && ! rtx_equal_p (new_reg_base_value[ui], reg_base_value[ui]))
2570 reg_base_value[ui] = new_reg_base_value[ui];
2575 while (changed && ++pass < MAX_ALIAS_LOOP_PASSES);
2577 /* Fill in the remaining entries. */
2578 for (i = FIRST_PSEUDO_REGISTER; i < maxreg; i++)
2579 if (reg_known_value[i] == 0)
2580 reg_known_value[i] = regno_reg_rtx[i];
2582 /* Simplify the reg_base_value array so that no register refers to
2583 another register, except to special registers indirectly through
2584 ADDRESS expressions.
2586 In theory this loop can take as long as O(registers^2), but unless
2587 there are very long dependency chains it will run in close to linear
2590 This loop may not be needed any longer now that the main loop does
2591 a better job at propagating alias information. */
2597 for (ui = 0; ui < reg_base_value_size; ui++)
2599 rtx base = reg_base_value[ui];
2600 if (base && GET_CODE (base) == REG)
2602 unsigned int base_regno = REGNO (base);
2603 if (base_regno == ui) /* register set from itself */
2604 reg_base_value[ui] = 0;
2606 reg_base_value[ui] = reg_base_value[base_regno];
2611 while (changed && pass < MAX_ALIAS_LOOP_PASSES);
2614 free (new_reg_base_value);
2615 new_reg_base_value = 0;
2621 end_alias_analysis ()
2623 free (reg_known_value + FIRST_PSEUDO_REGISTER);
2624 reg_known_value = 0;
2625 reg_known_value_size = 0;
2626 free (reg_known_equiv_p + FIRST_PSEUDO_REGISTER);
2627 reg_known_equiv_p = 0;
2630 ggc_del_root (reg_base_value);
2631 free (reg_base_value);
2634 reg_base_value_size = 0;
2635 if (alias_invariant)
2637 free (alias_invariant);
2638 alias_invariant = 0;