1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
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
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
24 #include "coretypes.h"
29 #include "basic-block.h"
30 #include "tree-flow.h"
31 #include "tree-pass.h"
32 #include "tree-dump.h"
34 #include "diagnostic.h"
36 #include "tree-scalar-evolution.h"
37 #include "tree-ssa-propagate.h"
38 #include "tree-chrec.h"
40 /* Set of SSA names found during the dominator traversal of a
41 sub-graph in find_assert_locations. */
42 static sbitmap found_in_subgraph;
44 /* Loop structure of the program. Used to analyze scalar evolutions
45 inside adjust_range_with_scev. */
46 static struct loops *cfg_loops;
48 /* Local functions. */
49 static int compare_values (tree val1, tree val2);
51 /* Location information for ASSERT_EXPRs. Each instance of this
52 structure describes an ASSERT_EXPR for an SSA name. Since a single
53 SSA name may have more than one assertion associated with it, these
54 locations are kept in a linked list attached to the corresponding
58 /* Basic block where the assertion would be inserted. */
61 /* Some assertions need to be inserted on an edge (e.g., assertions
62 generated by COND_EXPRs). In those cases, BB will be NULL. */
65 /* Pointer to the statement that generated this assertion. */
66 block_stmt_iterator si;
68 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
69 enum tree_code comp_code;
71 /* Value being compared against. */
74 /* Next node in the linked list. */
75 struct assert_locus_d *next;
78 typedef struct assert_locus_d *assert_locus_t;
80 /* If bit I is present, it means that SSA name N_i has a list of
81 assertions that should be inserted in the IL. */
82 static bitmap need_assert_for;
84 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
85 holds a list of ASSERT_LOCUS_T nodes that describe where
86 ASSERT_EXPRs for SSA name N_I should be inserted. */
87 static assert_locus_t *asserts_for;
89 /* Set of blocks visited in find_assert_locations. Used to avoid
90 visiting the same block more than once. */
91 static sbitmap blocks_visited;
93 /* Value range array. After propagation, VR_VALUE[I] holds the range
94 of values that SSA name N_I may take. */
95 static value_range_t **vr_value;
98 /* Return true if ARG is marked with the nonnull attribute in the
99 current function signature. */
102 nonnull_arg_p (tree arg)
104 tree t, attrs, fntype;
105 unsigned HOST_WIDE_INT arg_num;
107 gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
109 fntype = TREE_TYPE (current_function_decl);
110 attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype));
112 /* If "nonnull" wasn't specified, we know nothing about the argument. */
113 if (attrs == NULL_TREE)
116 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
117 if (TREE_VALUE (attrs) == NULL_TREE)
120 /* Get the position number for ARG in the function signature. */
121 for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl);
123 t = TREE_CHAIN (t), arg_num++)
129 gcc_assert (t == arg);
131 /* Now see if ARG_NUM is mentioned in the nonnull list. */
132 for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
134 if (compare_tree_int (TREE_VALUE (t), arg_num) == 0)
142 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
145 set_value_range (value_range_t *vr, enum value_range_type t, tree min,
146 tree max, bitmap equiv)
148 #if defined ENABLE_CHECKING
149 /* Check the validity of the range. */
150 if (t == VR_RANGE || t == VR_ANTI_RANGE)
154 gcc_assert (min && max);
156 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
157 gcc_assert (min != TYPE_MIN_VALUE (TREE_TYPE (min))
158 || max != TYPE_MAX_VALUE (TREE_TYPE (max)));
160 cmp = compare_values (min, max);
161 gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
164 if (t == VR_UNDEFINED || t == VR_VARYING)
165 gcc_assert (min == NULL_TREE && max == NULL_TREE);
167 if (t == VR_UNDEFINED || t == VR_VARYING)
168 gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
175 /* Since updating the equivalence set involves deep copying the
176 bitmaps, only do it if absolutely necessary. */
177 if (vr->equiv == NULL)
178 vr->equiv = BITMAP_ALLOC (NULL);
180 if (equiv != vr->equiv)
182 if (equiv && !bitmap_empty_p (equiv))
183 bitmap_copy (vr->equiv, equiv);
185 bitmap_clear (vr->equiv);
190 /* Copy value range FROM into value range TO. */
193 copy_value_range (value_range_t *to, value_range_t *from)
195 set_value_range (to, from->type, from->min, from->max, from->equiv);
199 /* Set value range VR to a non-NULL range of type TYPE. */
202 set_value_range_to_nonnull (value_range_t *vr, tree type)
204 tree zero = build_int_cst (type, 0);
205 set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
209 /* Set value range VR to a NULL range of type TYPE. */
212 set_value_range_to_null (value_range_t *vr, tree type)
214 tree zero = build_int_cst (type, 0);
215 set_value_range (vr, VR_RANGE, zero, zero, vr->equiv);
219 /* Set value range VR to VR_VARYING. */
222 set_value_range_to_varying (value_range_t *vr)
224 vr->type = VR_VARYING;
225 vr->min = vr->max = NULL_TREE;
227 bitmap_clear (vr->equiv);
231 /* Set value range VR to VR_UNDEFINED. */
234 set_value_range_to_undefined (value_range_t *vr)
236 vr->type = VR_UNDEFINED;
237 vr->min = vr->max = NULL_TREE;
239 bitmap_clear (vr->equiv);
243 /* Return value range information for VAR. Create an empty range
246 static value_range_t *
247 get_value_range (tree var)
251 unsigned ver = SSA_NAME_VERSION (var);
257 /* Create a default value range. */
258 vr_value[ver] = vr = xmalloc (sizeof (*vr));
259 memset (vr, 0, sizeof (*vr));
261 /* Allocate an equivalence set. */
262 vr->equiv = BITMAP_ALLOC (NULL);
264 /* If VAR is a default definition, the variable can take any value
266 sym = SSA_NAME_VAR (var);
267 if (var == default_def (sym))
269 /* Try to use the "nonnull" attribute to create ~[0, 0]
270 anti-ranges for pointers. Note that this is only valid with
271 default definitions of PARM_DECLs. */
272 if (TREE_CODE (sym) == PARM_DECL
273 && POINTER_TYPE_P (TREE_TYPE (sym))
274 && nonnull_arg_p (sym))
275 set_value_range_to_nonnull (vr, TREE_TYPE (sym));
277 set_value_range_to_varying (vr);
284 /* Update the value range and equivalence set for variable VAR to
285 NEW_VR. Return true if NEW_VR is different from VAR's previous
288 NOTE: This function assumes that NEW_VR is a temporary value range
289 object created for the sole purpose of updating VAR's range. The
290 storage used by the equivalence set from NEW_VR will be freed by
291 this function. Do not call update_value_range when NEW_VR
292 is the range object associated with another SSA name. */
295 update_value_range (tree var, value_range_t *new_vr)
297 value_range_t *old_vr;
300 /* Update the value range, if necessary. */
301 old_vr = get_value_range (var);
302 is_new = old_vr->type != new_vr->type
303 || old_vr->min != new_vr->min
304 || old_vr->max != new_vr->max
305 || (old_vr->equiv == NULL && new_vr->equiv)
306 || (old_vr->equiv && new_vr->equiv == NULL)
307 || (!bitmap_equal_p (old_vr->equiv, new_vr->equiv));
310 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
313 BITMAP_FREE (new_vr->equiv);
314 new_vr->equiv = NULL;
320 /* Add VAR and VAR's equivalence set to EQUIV. */
323 add_equivalence (bitmap equiv, tree var)
325 unsigned ver = SSA_NAME_VERSION (var);
326 value_range_t *vr = vr_value[ver];
328 bitmap_set_bit (equiv, ver);
330 bitmap_ior_into (equiv, vr->equiv);
334 /* Return true if VR is ~[0, 0]. */
337 range_is_nonnull (value_range_t *vr)
339 return vr->type == VR_ANTI_RANGE
340 && integer_zerop (vr->min)
341 && integer_zerop (vr->max);
345 /* Return true if VR is [0, 0]. */
348 range_is_null (value_range_t *vr)
350 return vr->type == VR_RANGE
351 && integer_zerop (vr->min)
352 && integer_zerop (vr->max);
356 /* Return true if value range VR involves at least one symbol. */
359 symbolic_range_p (value_range_t *vr)
361 return (!is_gimple_min_invariant (vr->min)
362 || !is_gimple_min_invariant (vr->max));
366 /* Like tree_expr_nonzero_p, but this function uses value ranges
370 vrp_expr_computes_nonzero (tree expr)
372 if (tree_expr_nonzero_p (expr))
375 /* If we have an expression of the form &X->a, then the expression
376 is nonnull if X is nonnull. */
377 if (TREE_CODE (expr) == ADDR_EXPR)
379 tree base = get_base_address (TREE_OPERAND (expr, 0));
381 if (base != NULL_TREE
382 && TREE_CODE (base) == INDIRECT_REF
383 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
385 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
386 if (range_is_nonnull (vr))
395 /* Compare two values VAL1 and VAL2. Return
397 -2 if VAL1 and VAL2 cannot be compared at compile-time,
400 +1 if VAL1 > VAL2, and
403 This is similar to tree_int_cst_compare but supports pointer values
404 and values that cannot be compared at compile time. */
407 compare_values (tree val1, tree val2)
412 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
414 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
415 == POINTER_TYPE_P (TREE_TYPE (val2)));
417 /* Do some limited symbolic comparisons. */
418 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
420 /* We can determine some comparisons against +INF and -INF even
421 if the other value is an expression. */
422 if (val1 == TYPE_MAX_VALUE (TREE_TYPE (val1))
423 && TREE_CODE (val2) == MINUS_EXPR)
425 /* +INF > NAME - CST. */
428 else if (val1 == TYPE_MIN_VALUE (TREE_TYPE (val1))
429 && TREE_CODE (val2) == PLUS_EXPR)
431 /* -INF < NAME + CST. */
434 else if (TREE_CODE (val1) == MINUS_EXPR
435 && val2 == TYPE_MAX_VALUE (TREE_TYPE (val2)))
437 /* NAME - CST < +INF. */
440 else if (TREE_CODE (val1) == PLUS_EXPR
441 && val2 == TYPE_MIN_VALUE (TREE_TYPE (val2)))
443 /* NAME + CST > -INF. */
448 if ((TREE_CODE (val1) == SSA_NAME
449 || TREE_CODE (val1) == PLUS_EXPR
450 || TREE_CODE (val1) == MINUS_EXPR)
451 && (TREE_CODE (val2) == SSA_NAME
452 || TREE_CODE (val2) == PLUS_EXPR
453 || TREE_CODE (val2) == MINUS_EXPR))
457 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
458 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
459 same name, return -2. */
460 if (TREE_CODE (val1) == SSA_NAME)
467 n1 = TREE_OPERAND (val1, 0);
468 c1 = TREE_OPERAND (val1, 1);
471 if (TREE_CODE (val2) == SSA_NAME)
478 n2 = TREE_OPERAND (val2, 0);
479 c2 = TREE_OPERAND (val2, 1);
482 /* Both values must use the same name. */
486 if (TREE_CODE (val1) == SSA_NAME)
488 if (TREE_CODE (val2) == SSA_NAME)
491 else if (TREE_CODE (val2) == PLUS_EXPR)
492 /* NAME < NAME + CST */
494 else if (TREE_CODE (val2) == MINUS_EXPR)
495 /* NAME > NAME - CST */
498 else if (TREE_CODE (val1) == PLUS_EXPR)
500 if (TREE_CODE (val2) == SSA_NAME)
501 /* NAME + CST > NAME */
503 else if (TREE_CODE (val2) == PLUS_EXPR)
504 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
505 return compare_values (c1, c2);
506 else if (TREE_CODE (val2) == MINUS_EXPR)
507 /* NAME + CST1 > NAME - CST2 */
510 else if (TREE_CODE (val1) == MINUS_EXPR)
512 if (TREE_CODE (val2) == SSA_NAME)
513 /* NAME - CST < NAME */
515 else if (TREE_CODE (val2) == PLUS_EXPR)
516 /* NAME - CST1 < NAME + CST2 */
518 else if (TREE_CODE (val2) == MINUS_EXPR)
519 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
520 C1 and C2 are swapped in the call to compare_values. */
521 return compare_values (c2, c1);
527 /* We cannot compare non-constants. */
528 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
531 /* We cannot compare overflowed values. */
532 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
535 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
536 return tree_int_cst_compare (val1, val2);
541 /* First see if VAL1 and VAL2 are not the same. */
542 if (val1 == val2 || operand_equal_p (val1, val2, 0))
545 /* If VAL1 is a lower address than VAL2, return -1. */
546 t = fold_binary (LT_EXPR, boolean_type_node, val1, val2);
547 if (t == boolean_true_node)
550 /* If VAL1 is a higher address than VAL2, return +1. */
551 t = fold_binary (GT_EXPR, boolean_type_node, val1, val2);
552 if (t == boolean_true_node)
555 /* If VAL1 is different than VAL2, return +2. */
556 t = fold_binary (NE_EXPR, boolean_type_node, val1, val2);
557 if (t == boolean_true_node)
565 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
566 0 if VAL is not inside VR,
567 -2 if we cannot tell either way.
569 FIXME, the current semantics of this functions are a bit quirky
570 when taken in the context of VRP. In here we do not care
571 about VR's type. If VR is the anti-range ~[3, 5] the call
572 value_inside_range (4, VR) will return 1.
574 This is counter-intuitive in a strict sense, but the callers
575 currently expect this. They are calling the function
576 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
577 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
580 This also applies to value_ranges_intersect_p and
581 range_includes_zero_p. The semantics of VR_RANGE and
582 VR_ANTI_RANGE should be encoded here, but that also means
583 adapting the users of these functions to the new semantics. */
586 value_inside_range (tree val, value_range_t *vr)
590 cmp1 = compare_values (val, vr->min);
591 if (cmp1 == -2 || cmp1 == 2)
594 cmp2 = compare_values (val, vr->max);
595 if (cmp2 == -2 || cmp2 == 2)
598 return (cmp1 == 0 || cmp1 == 1) && (cmp2 == -1 || cmp2 == 0);
602 /* Return true if value ranges VR0 and VR1 have a non-empty
606 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
608 return (value_inside_range (vr1->min, vr0) == 1
609 || value_inside_range (vr1->max, vr0) == 1
610 || value_inside_range (vr0->min, vr1) == 1
611 || value_inside_range (vr0->max, vr1) == 1);
615 /* Return true if VR includes the value zero, false otherwise. FIXME,
616 currently this will return false for an anti-range like ~[-4, 3].
617 This will be wrong when the semantics of value_inside_range are
618 modified (currently the users of this function expect these
622 range_includes_zero_p (value_range_t *vr)
626 gcc_assert (vr->type != VR_UNDEFINED
627 && vr->type != VR_VARYING
628 && !symbolic_range_p (vr));
630 zero = build_int_cst (TREE_TYPE (vr->min), 0);
631 return (value_inside_range (zero, vr) == 1);
635 /* When extracting ranges from X_i = ASSERT_EXPR <Y_j, pred>, we will
636 initially consider X_i and Y_j equivalent, so the equivalence set
637 of Y_j is added to the equivalence set of X_i. However, it is
638 possible to have a chain of ASSERT_EXPRs whose predicates are
639 actually incompatible. This is usually the result of nesting of
640 contradictory if-then-else statements. For instance, in PR 24670:
642 count_4 has range [-INF, 63]
646 count_19 = ASSERT_EXPR <count_4, count_4 != 0>
649 count_18 = ASSERT_EXPR <count_19, count_19 > 63>
655 Notice that 'if (count_19 > 63)' is trivially false and will be
656 folded out at the end. However, during propagation, the flowgraph
657 is not cleaned up and so, VRP will evaluate predicates more
658 predicates than necessary, so it must support these
659 inconsistencies. The problem here is that because of the chaining
660 of ASSERT_EXPRs, the equivalency set for count_18 includes count_4.
661 Since count_4 has an incompatible range, we ICE when evaluating the
662 ranges in the equivalency set. So, we need to remove count_4 from
666 fix_equivalence_set (value_range_t *vr_p)
670 bitmap e = vr_p->equiv;
671 bitmap to_remove = BITMAP_ALLOC (NULL);
673 /* Only detect inconsistencies on numeric ranges. */
674 if (vr_p->type == VR_VARYING
675 || vr_p->type == VR_UNDEFINED
676 || symbolic_range_p (vr_p))
679 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
681 value_range_t *equiv_vr = vr_value[i];
683 if (equiv_vr->type == VR_VARYING
684 || equiv_vr->type == VR_UNDEFINED
685 || symbolic_range_p (equiv_vr))
688 if (equiv_vr->type == VR_RANGE
689 && vr_p->type == VR_RANGE
690 && !value_ranges_intersect_p (vr_p, equiv_vr))
691 bitmap_set_bit (to_remove, i);
692 else if ((equiv_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
693 || (equiv_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
695 /* A range and an anti-range have an empty intersection if
696 their end points are the same. FIXME,
697 value_ranges_intersect_p should handle this
699 if (compare_values (equiv_vr->min, vr_p->min) == 0
700 && compare_values (equiv_vr->max, vr_p->max) == 0)
701 bitmap_set_bit (to_remove, i);
705 bitmap_and_compl_into (vr_p->equiv, to_remove);
706 BITMAP_FREE (to_remove);
710 /* Extract value range information from an ASSERT_EXPR EXPR and store
714 extract_range_from_assert (value_range_t *vr_p, tree expr)
716 tree var, cond, limit, min, max, type;
717 value_range_t *var_vr, *limit_vr;
718 enum tree_code cond_code;
720 var = ASSERT_EXPR_VAR (expr);
721 cond = ASSERT_EXPR_COND (expr);
723 gcc_assert (COMPARISON_CLASS_P (cond));
725 /* Find VAR in the ASSERT_EXPR conditional. */
726 if (var == TREE_OPERAND (cond, 0))
728 /* If the predicate is of the form VAR COMP LIMIT, then we just
729 take LIMIT from the RHS and use the same comparison code. */
730 limit = TREE_OPERAND (cond, 1);
731 cond_code = TREE_CODE (cond);
735 /* If the predicate is of the form LIMIT COMP VAR, then we need
736 to flip around the comparison code to create the proper range
738 limit = TREE_OPERAND (cond, 0);
739 cond_code = swap_tree_comparison (TREE_CODE (cond));
742 type = TREE_TYPE (limit);
743 gcc_assert (limit != var);
745 /* For pointer arithmetic, we only keep track of pointer equality
747 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
749 set_value_range_to_varying (vr_p);
753 /* If LIMIT is another SSA name and LIMIT has a range of its own,
754 try to use LIMIT's range to avoid creating symbolic ranges
756 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
758 /* LIMIT's range is only interesting if it has any useful information. */
760 && (limit_vr->type == VR_UNDEFINED
761 || limit_vr->type == VR_VARYING
762 || symbolic_range_p (limit_vr)))
765 /* Special handling for integral types with super-types. Some FEs
766 construct integral types derived from other types and restrict
767 the range of values these new types may take.
769 It may happen that LIMIT is actually smaller than TYPE's minimum
770 value. For instance, the Ada FE is generating code like this
773 D.1480_32 = nam_30 - 300000361;
774 if (D.1480_32 <= 1) goto <L112>; else goto <L52>;
776 D.1480_94 = ASSERT_EXPR <D.1480_32, D.1480_32 <= 1>;
778 All the names are of type types__name_id___XDLU_300000000__399999999
779 which has min == 300000000 and max == 399999999. This means that
780 the ASSERT_EXPR would try to create the range [3000000, 1] which
783 The fact that the type specifies MIN and MAX values does not
784 automatically mean that every variable of that type will always
785 be within that range, so the predicate may well be true at run
786 time. If we had symbolic -INF and +INF values, we could
787 represent this range, but we currently represent -INF and +INF
788 using the type's min and max values.
790 So, the only sensible thing we can do for now is set the
791 resulting range to VR_VARYING. TODO, would having symbolic -INF
792 and +INF values be worth the trouble? */
793 if (TREE_CODE (limit) != SSA_NAME
794 && INTEGRAL_TYPE_P (type)
797 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
799 tree type_min = TYPE_MIN_VALUE (type);
800 int cmp = compare_values (limit, type_min);
802 /* For < or <= comparisons, if LIMIT is smaller than
803 TYPE_MIN, set the range to VR_VARYING. */
804 if (cmp == -1 || cmp == 0)
806 set_value_range_to_varying (vr_p);
810 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
812 tree type_max = TYPE_MIN_VALUE (type);
813 int cmp = compare_values (limit, type_max);
815 /* For > or >= comparisons, if LIMIT is bigger than
816 TYPE_MAX, set the range to VR_VARYING. */
817 if (cmp == 1 || cmp == 0)
819 set_value_range_to_varying (vr_p);
825 /* Initially, the new range has the same set of equivalences of
826 VAR's range. This will be revised before returning the final
827 value. Since assertions may be chained via mutually exclusive
828 predicates, we will need to trim the set of equivalences before
830 gcc_assert (vr_p->equiv == NULL);
831 vr_p->equiv = BITMAP_ALLOC (NULL);
832 add_equivalence (vr_p->equiv, var);
834 /* Extract a new range based on the asserted comparison for VAR and
835 LIMIT's value range. Notice that if LIMIT has an anti-range, we
836 will only use it for equality comparisons (EQ_EXPR). For any
837 other kind of assertion, we cannot derive a range from LIMIT's
838 anti-range that can be used to describe the new range. For
839 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
840 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
841 no single range for x_2 that could describe LE_EXPR, so we might
842 as well build the range [b_4, +INF] for it. */
843 if (cond_code == EQ_EXPR)
845 enum value_range_type range_type;
849 range_type = limit_vr->type;
855 range_type = VR_RANGE;
860 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
862 /* When asserting the equality VAR == LIMIT and LIMIT is another
863 SSA name, the new range will also inherit the equivalence set
865 if (TREE_CODE (limit) == SSA_NAME)
866 add_equivalence (vr_p->equiv, limit);
868 else if (cond_code == NE_EXPR)
870 /* As described above, when LIMIT's range is an anti-range and
871 this assertion is an inequality (NE_EXPR), then we cannot
872 derive anything from the anti-range. For instance, if
873 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
874 not imply that VAR's range is [0, 0]. So, in the case of
875 anti-ranges, we just assert the inequality using LIMIT and
878 If LIMIT_VR is a range, we can only use it to build a new
879 anti-range if LIMIT_VR is a single-valued range. For
880 instance, if LIMIT_VR is [0, 1], the predicate
881 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
882 Rather, it means that for value 0 VAR should be ~[0, 0]
883 and for value 1, VAR should be ~[1, 1]. We cannot
884 represent these ranges.
886 The only situation in which we can build a valid
887 anti-range is when LIMIT_VR is a single-valued range
888 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
889 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
891 && limit_vr->type == VR_RANGE
892 && compare_values (limit_vr->min, limit_vr->max) == 0)
899 /* In any other case, we cannot use LIMIT's range to build a
904 /* If MIN and MAX cover the whole range for their type, then
905 just use the original LIMIT. */
906 if (INTEGRAL_TYPE_P (type)
907 && min == TYPE_MIN_VALUE (type)
908 && max == TYPE_MAX_VALUE (type))
911 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
913 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
915 min = TYPE_MIN_VALUE (type);
917 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
921 /* If LIMIT_VR is of the form [N1, N2], we need to build the
922 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
927 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
928 if (cond_code == LT_EXPR)
930 tree one = build_int_cst (type, 1);
931 max = fold_build2 (MINUS_EXPR, type, max, one);
934 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
936 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
938 max = TYPE_MAX_VALUE (type);
940 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
944 /* If LIMIT_VR is of the form [N1, N2], we need to build the
945 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
950 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
951 if (cond_code == GT_EXPR)
953 tree one = build_int_cst (type, 1);
954 min = fold_build2 (PLUS_EXPR, type, min, one);
957 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
962 /* If VAR already had a known range, it may happen that the new
963 range we have computed and VAR's range are not compatible. For
967 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
969 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
971 While the above comes from a faulty program, it will cause an ICE
972 later because p_8 and p_6 will have incompatible ranges and at
973 the same time will be considered equivalent. A similar situation
977 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
979 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
981 Again i_6 and i_7 will have incompatible ranges. It would be
982 pointless to try and do anything with i_7's range because
983 anything dominated by 'if (i_5 < 5)' will be optimized away.
984 Note, due to the wa in which simulation proceeds, the statement
985 i_7 = ASSERT_EXPR <...> we would never be visited because the
986 conditional 'if (i_5 < 5)' always evaluates to false. However,
987 this extra check does not hurt and may protect against future
988 changes to VRP that may get into a situation similar to the
989 NULL pointer dereference example.
991 Note that these compatibility tests are only needed when dealing
992 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
993 are both anti-ranges, they will always be compatible, because two
994 anti-ranges will always have a non-empty intersection. */
996 var_vr = get_value_range (var);
998 /* We may need to make adjustments when VR_P and VAR_VR are numeric
999 ranges or anti-ranges. */
1000 if (vr_p->type == VR_VARYING
1001 || vr_p->type == VR_UNDEFINED
1002 || var_vr->type == VR_VARYING
1003 || var_vr->type == VR_UNDEFINED
1004 || symbolic_range_p (vr_p)
1005 || symbolic_range_p (var_vr))
1008 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
1010 /* If the two ranges have a non-empty intersection, we can
1011 refine the resulting range. Since the assert expression
1012 creates an equivalency and at the same time it asserts a
1013 predicate, we can take the intersection of the two ranges to
1014 get better precision. */
1015 if (value_ranges_intersect_p (var_vr, vr_p))
1017 /* Use the larger of the two minimums. */
1018 if (compare_values (vr_p->min, var_vr->min) == -1)
1023 /* Use the smaller of the two maximums. */
1024 if (compare_values (vr_p->max, var_vr->max) == 1)
1029 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
1033 /* The two ranges do not intersect, set the new range to
1034 VARYING, because we will not be able to do anything
1035 meaningful with it. */
1036 set_value_range_to_varying (vr_p);
1039 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
1040 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
1042 /* A range and an anti-range will cancel each other only if
1043 their ends are the same. For instance, in the example above,
1044 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1045 so VR_P should be set to VR_VARYING. */
1046 if (compare_values (var_vr->min, vr_p->min) == 0
1047 && compare_values (var_vr->max, vr_p->max) == 0)
1048 set_value_range_to_varying (vr_p);
1051 /* Remove names from the equivalence set that have ranges
1052 incompatible with VR_P. */
1054 fix_equivalence_set (vr_p);
1058 /* Extract range information from SSA name VAR and store it in VR. If
1059 VAR has an interesting range, use it. Otherwise, create the
1060 range [VAR, VAR] and return it. This is useful in situations where
1061 we may have conditionals testing values of VARYING names. For
1068 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1072 extract_range_from_ssa_name (value_range_t *vr, tree var)
1074 value_range_t *var_vr = get_value_range (var);
1076 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
1077 copy_value_range (vr, var_vr);
1079 set_value_range (vr, VR_RANGE, var, var, NULL);
1081 add_equivalence (vr->equiv, var);
1085 /* Wrapper around int_const_binop. If the operation overflows and we
1086 are not using wrapping arithmetic, then adjust the result to be
1087 -INF or +INF depending on CODE, VAL1 and VAL2. */
1090 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
1095 return int_const_binop (code, val1, val2, 0);
1097 /* If we are not using wrapping arithmetic, operate symbolically
1098 on -INF and +INF. */
1099 res = int_const_binop (code, val1, val2, 0);
1101 if (TYPE_UNSIGNED (TREE_TYPE (val1)))
1103 int checkz = compare_values (res, val1);
1105 /* Ensure that res = val1 + val2 >= val1
1106 or that res = val1 - val2 <= val1. */
1107 if ((code == PLUS_EXPR && !(checkz == 1 || checkz == 0))
1108 || (code == MINUS_EXPR && !(checkz == 0 || checkz == -1)))
1110 res = copy_node (res);
1111 TREE_OVERFLOW (res) = 1;
1114 /* If the operation overflowed but neither VAL1 nor VAL2 are
1115 overflown, return -INF or +INF depending on the operation
1116 and the combination of signs of the operands. */
1117 else if (TREE_OVERFLOW (res)
1118 && !TREE_OVERFLOW (val1)
1119 && !TREE_OVERFLOW (val2))
1121 int sgn1 = tree_int_cst_sgn (val1);
1122 int sgn2 = tree_int_cst_sgn (val2);
1124 /* Notice that we only need to handle the restricted set of
1125 operations handled by extract_range_from_binary_expr.
1126 Among them, only multiplication, addition and subtraction
1127 can yield overflow without overflown operands because we
1128 are working with integral types only... except in the
1129 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1130 for division too. */
1132 /* For multiplication, the sign of the overflow is given
1133 by the comparison of the signs of the operands. */
1134 if ((code == MULT_EXPR && sgn1 == sgn2)
1135 /* For addition, the operands must be of the same sign
1136 to yield an overflow. Its sign is therefore that
1137 of one of the operands, for example the first. */
1138 || (code == PLUS_EXPR && sgn1 > 0)
1139 /* For subtraction, the operands must be of different
1140 signs to yield an overflow. Its sign is therefore
1141 that of the first operand or the opposite of that
1142 of the second operand. A first operand of 0 counts
1143 as positive here, for the corner case 0 - (-INF),
1144 which overflows, but must yield +INF. */
1145 || (code == MINUS_EXPR && sgn1 >= 0)
1146 /* For division, the only case is -INF / -1 = +INF. */
1147 || code == TRUNC_DIV_EXPR
1148 || code == FLOOR_DIV_EXPR
1149 || code == CEIL_DIV_EXPR
1150 || code == EXACT_DIV_EXPR
1151 || code == ROUND_DIV_EXPR)
1152 return TYPE_MAX_VALUE (TREE_TYPE (res));
1154 return TYPE_MIN_VALUE (TREE_TYPE (res));
1161 /* Extract range information from a binary expression EXPR based on
1162 the ranges of each of its operands and the expression code. */
1165 extract_range_from_binary_expr (value_range_t *vr, tree expr)
1167 enum tree_code code = TREE_CODE (expr);
1168 tree op0, op1, min, max;
1170 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1171 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1173 /* Not all binary expressions can be applied to ranges in a
1174 meaningful way. Handle only arithmetic operations. */
1175 if (code != PLUS_EXPR
1176 && code != MINUS_EXPR
1177 && code != MULT_EXPR
1178 && code != TRUNC_DIV_EXPR
1179 && code != FLOOR_DIV_EXPR
1180 && code != CEIL_DIV_EXPR
1181 && code != EXACT_DIV_EXPR
1182 && code != ROUND_DIV_EXPR
1185 && code != TRUTH_ANDIF_EXPR
1186 && code != TRUTH_ORIF_EXPR
1187 && code != TRUTH_AND_EXPR
1188 && code != TRUTH_OR_EXPR
1189 && code != TRUTH_XOR_EXPR)
1191 set_value_range_to_varying (vr);
1195 /* Get value ranges for each operand. For constant operands, create
1196 a new value range with the operand to simplify processing. */
1197 op0 = TREE_OPERAND (expr, 0);
1198 if (TREE_CODE (op0) == SSA_NAME)
1199 vr0 = *(get_value_range (op0));
1200 else if (is_gimple_min_invariant (op0))
1201 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1203 set_value_range_to_varying (&vr0);
1205 op1 = TREE_OPERAND (expr, 1);
1206 if (TREE_CODE (op1) == SSA_NAME)
1207 vr1 = *(get_value_range (op1));
1208 else if (is_gimple_min_invariant (op1))
1209 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1211 set_value_range_to_varying (&vr1);
1213 /* If either range is UNDEFINED, so is the result. */
1214 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1216 set_value_range_to_undefined (vr);
1220 /* Refuse to operate on VARYING ranges, ranges of different kinds
1221 and symbolic ranges. TODO, we may be able to derive anti-ranges
1223 if (vr0.type == VR_VARYING
1224 || vr1.type == VR_VARYING
1225 || vr0.type != vr1.type
1226 || symbolic_range_p (&vr0)
1227 || symbolic_range_p (&vr1))
1229 set_value_range_to_varying (vr);
1233 /* Now evaluate the expression to determine the new range. */
1234 if (POINTER_TYPE_P (TREE_TYPE (expr))
1235 || POINTER_TYPE_P (TREE_TYPE (op0))
1236 || POINTER_TYPE_P (TREE_TYPE (op1)))
1238 /* For pointer types, we are really only interested in asserting
1239 whether the expression evaluates to non-NULL. FIXME, we used
1240 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1241 ivopts is generating expressions with pointer multiplication
1243 if (code == PLUS_EXPR)
1245 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1246 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1247 else if (range_is_null (&vr0) && range_is_null (&vr1))
1248 set_value_range_to_null (vr, TREE_TYPE (expr));
1250 set_value_range_to_varying (vr);
1254 /* Subtracting from a pointer, may yield 0, so just drop the
1255 resulting range to varying. */
1256 set_value_range_to_varying (vr);
1262 /* For integer ranges, apply the operation to each end of the
1263 range and see what we end up with. */
1264 if (code == TRUTH_ANDIF_EXPR
1265 || code == TRUTH_ORIF_EXPR
1266 || code == TRUTH_AND_EXPR
1267 || code == TRUTH_OR_EXPR
1268 || code == TRUTH_XOR_EXPR)
1270 /* Boolean expressions cannot be folded with int_const_binop. */
1271 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1272 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1274 else if (code == PLUS_EXPR
1276 || code == MAX_EXPR)
1278 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1279 VR_VARYING. It would take more effort to compute a precise
1280 range for such a case. For example, if we have op0 == 1 and
1281 op1 == -1 with their ranges both being ~[0,0], we would have
1282 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1283 Note that we are guaranteed to have vr0.type == vr1.type at
1285 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1287 set_value_range_to_varying (vr);
1291 /* For operations that make the resulting range directly
1292 proportional to the original ranges, apply the operation to
1293 the same end of each range. */
1294 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1295 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1297 else if (code == MULT_EXPR
1298 || code == TRUNC_DIV_EXPR
1299 || code == FLOOR_DIV_EXPR
1300 || code == CEIL_DIV_EXPR
1301 || code == EXACT_DIV_EXPR
1302 || code == ROUND_DIV_EXPR)
1307 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1308 drop to VR_VARYING. It would take more effort to compute a
1309 precise range for such a case. For example, if we have
1310 op0 == 65536 and op1 == 65536 with their ranges both being
1311 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1312 we cannot claim that the product is in ~[0,0]. Note that we
1313 are guaranteed to have vr0.type == vr1.type at this
1315 if (code == MULT_EXPR
1316 && vr0.type == VR_ANTI_RANGE
1317 && (flag_wrapv || TYPE_UNSIGNED (TREE_TYPE (op0))))
1319 set_value_range_to_varying (vr);
1323 /* Multiplications and divisions are a bit tricky to handle,
1324 depending on the mix of signs we have in the two ranges, we
1325 need to operate on different values to get the minimum and
1326 maximum values for the new range. One approach is to figure
1327 out all the variations of range combinations and do the
1330 However, this involves several calls to compare_values and it
1331 is pretty convoluted. It's simpler to do the 4 operations
1332 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1333 MAX1) and then figure the smallest and largest values to form
1336 /* Divisions by zero result in a VARYING value. */
1337 if (code != MULT_EXPR
1338 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1340 set_value_range_to_varying (vr);
1344 /* Compute the 4 cross operations. */
1345 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1347 val[1] = (vr1.max != vr1.min)
1348 ? vrp_int_const_binop (code, vr0.min, vr1.max)
1351 val[2] = (vr0.max != vr0.min)
1352 ? vrp_int_const_binop (code, vr0.max, vr1.min)
1355 val[3] = (vr0.min != vr0.max && vr1.min != vr1.max)
1356 ? vrp_int_const_binop (code, vr0.max, vr1.max)
1359 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1363 for (i = 1; i < 4; i++)
1365 if (TREE_OVERFLOW (min) || TREE_OVERFLOW (max))
1370 if (TREE_OVERFLOW (val[i]))
1372 /* If we found an overflowed value, set MIN and MAX
1373 to it so that we set the resulting range to
1379 if (compare_values (val[i], min) == -1)
1382 if (compare_values (val[i], max) == 1)
1387 else if (code == MINUS_EXPR)
1389 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1390 VR_VARYING. It would take more effort to compute a precise
1391 range for such a case. For example, if we have op0 == 1 and
1392 op1 == 1 with their ranges both being ~[0,0], we would have
1393 op0 - op1 == 0, so we cannot claim that the difference is in
1394 ~[0,0]. Note that we are guaranteed to have
1395 vr0.type == vr1.type at this point. */
1396 if (vr0.type == VR_ANTI_RANGE)
1398 set_value_range_to_varying (vr);
1402 /* For MINUS_EXPR, apply the operation to the opposite ends of
1404 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1405 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1410 /* If either MIN or MAX overflowed, then set the resulting range to
1412 if (TREE_OVERFLOW (min) || TREE_OVERFLOW (max))
1414 set_value_range_to_varying (vr);
1418 cmp = compare_values (min, max);
1419 if (cmp == -2 || cmp == 1)
1421 /* If the new range has its limits swapped around (MIN > MAX),
1422 then the operation caused one of them to wrap around, mark
1423 the new range VARYING. */
1424 set_value_range_to_varying (vr);
1427 set_value_range (vr, vr0.type, min, max, NULL);
1431 /* Extract range information from a unary expression EXPR based on
1432 the range of its operand and the expression code. */
1435 extract_range_from_unary_expr (value_range_t *vr, tree expr)
1437 enum tree_code code = TREE_CODE (expr);
1440 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1442 /* Refuse to operate on certain unary expressions for which we
1443 cannot easily determine a resulting range. */
1444 if (code == FIX_TRUNC_EXPR
1445 || code == FIX_CEIL_EXPR
1446 || code == FIX_FLOOR_EXPR
1447 || code == FIX_ROUND_EXPR
1448 || code == FLOAT_EXPR
1449 || code == BIT_NOT_EXPR
1450 || code == NON_LVALUE_EXPR
1451 || code == CONJ_EXPR)
1453 set_value_range_to_varying (vr);
1457 /* Get value ranges for the operand. For constant operands, create
1458 a new value range with the operand to simplify processing. */
1459 op0 = TREE_OPERAND (expr, 0);
1460 if (TREE_CODE (op0) == SSA_NAME)
1461 vr0 = *(get_value_range (op0));
1462 else if (is_gimple_min_invariant (op0))
1463 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1465 set_value_range_to_varying (&vr0);
1467 /* If VR0 is UNDEFINED, so is the result. */
1468 if (vr0.type == VR_UNDEFINED)
1470 set_value_range_to_undefined (vr);
1474 /* Refuse to operate on varying and symbolic ranges. Also, if the
1475 operand is neither a pointer nor an integral type, set the
1476 resulting range to VARYING. TODO, in some cases we may be able
1477 to derive anti-ranges (like nonzero values). */
1478 if (vr0.type == VR_VARYING
1479 || (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
1480 && !POINTER_TYPE_P (TREE_TYPE (op0)))
1481 || symbolic_range_p (&vr0))
1483 set_value_range_to_varying (vr);
1487 /* If the expression involves pointers, we are only interested in
1488 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1489 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
1491 if (range_is_nonnull (&vr0) || tree_expr_nonzero_p (expr))
1492 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1493 else if (range_is_null (&vr0))
1494 set_value_range_to_null (vr, TREE_TYPE (expr));
1496 set_value_range_to_varying (vr);
1501 /* Handle unary expressions on integer ranges. */
1502 if (code == NOP_EXPR || code == CONVERT_EXPR)
1504 tree inner_type = TREE_TYPE (op0);
1505 tree outer_type = TREE_TYPE (expr);
1507 /* If VR0 represents a simple range, then try to convert
1508 the min and max values for the range to the same type
1509 as OUTER_TYPE. If the results compare equal to VR0's
1510 min and max values and the new min is still less than
1511 or equal to the new max, then we can safely use the newly
1512 computed range for EXPR. This allows us to compute
1513 accurate ranges through many casts. */
1514 if (vr0.type == VR_RANGE)
1516 tree new_min, new_max;
1518 /* Convert VR0's min/max to OUTER_TYPE. */
1519 new_min = fold_convert (outer_type, vr0.min);
1520 new_max = fold_convert (outer_type, vr0.max);
1522 /* Verify the new min/max values are gimple values and
1523 that they compare equal to VR0's min/max values. */
1524 if (is_gimple_val (new_min)
1525 && is_gimple_val (new_max)
1526 && tree_int_cst_equal (new_min, vr0.min)
1527 && tree_int_cst_equal (new_max, vr0.max)
1528 && compare_values (new_min, new_max) <= 0
1529 && compare_values (new_min, new_max) >= -1)
1531 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
1536 /* When converting types of different sizes, set the result to
1537 VARYING. Things like sign extensions and precision loss may
1538 change the range. For instance, if x_3 is of type 'long long
1539 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1540 is impossible to know at compile time whether y_5 will be
1542 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
1543 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
1545 set_value_range_to_varying (vr);
1550 /* Apply the operation to each end of the range and see what we end
1552 if (code == NEGATE_EXPR
1553 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1555 /* NEGATE_EXPR flips the range around. */
1556 min = (vr0.max == TYPE_MAX_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
1557 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1558 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1560 max = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
1561 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1562 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1564 else if (code == ABS_EXPR
1565 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1567 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1570 && ((vr0.type == VR_RANGE
1571 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1572 || (vr0.type == VR_ANTI_RANGE
1573 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
1574 && !range_includes_zero_p (&vr0))))
1576 set_value_range_to_varying (vr);
1580 /* ABS_EXPR may flip the range around, if the original range
1581 included negative values. */
1582 min = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1583 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1584 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1586 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1588 cmp = compare_values (min, max);
1590 /* If a VR_ANTI_RANGEs contains zero, then we have
1591 ~[-INF, min(MIN, MAX)]. */
1592 if (vr0.type == VR_ANTI_RANGE)
1594 if (range_includes_zero_p (&vr0))
1596 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
1598 /* Take the lower of the two values. */
1602 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1603 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1604 flag_wrapv is set and the original anti-range doesn't include
1605 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1606 min = (flag_wrapv && vr0.min != type_min_value
1607 ? int_const_binop (PLUS_EXPR,
1609 integer_one_node, 0)
1614 /* All else has failed, so create the range [0, INF], even for
1615 flag_wrapv since TYPE_MIN_VALUE is in the original
1617 vr0.type = VR_RANGE;
1618 min = build_int_cst (TREE_TYPE (expr), 0);
1619 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
1623 /* If the range contains zero then we know that the minimum value in the
1624 range will be zero. */
1625 else if (range_includes_zero_p (&vr0))
1629 min = build_int_cst (TREE_TYPE (expr), 0);
1633 /* If the range was reversed, swap MIN and MAX. */
1644 /* Otherwise, operate on each end of the range. */
1645 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1646 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1649 cmp = compare_values (min, max);
1650 if (cmp == -2 || cmp == 1)
1652 /* If the new range has its limits swapped around (MIN > MAX),
1653 then the operation caused one of them to wrap around, mark
1654 the new range VARYING. */
1655 set_value_range_to_varying (vr);
1658 set_value_range (vr, vr0.type, min, max, NULL);
1662 /* Extract range information from a comparison expression EXPR based
1663 on the range of its operand and the expression code. */
1666 extract_range_from_comparison (value_range_t *vr, tree expr)
1668 tree val = vrp_evaluate_conditional (expr, false);
1671 /* Since this expression was found on the RHS of an assignment,
1672 its type may be different from _Bool. Convert VAL to EXPR's
1674 val = fold_convert (TREE_TYPE (expr), val);
1675 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
1678 set_value_range_to_varying (vr);
1682 /* Try to compute a useful range out of expression EXPR and store it
1686 extract_range_from_expr (value_range_t *vr, tree expr)
1688 enum tree_code code = TREE_CODE (expr);
1690 if (code == ASSERT_EXPR)
1691 extract_range_from_assert (vr, expr);
1692 else if (code == SSA_NAME)
1693 extract_range_from_ssa_name (vr, expr);
1694 else if (TREE_CODE_CLASS (code) == tcc_binary
1695 || code == TRUTH_ANDIF_EXPR
1696 || code == TRUTH_ORIF_EXPR
1697 || code == TRUTH_AND_EXPR
1698 || code == TRUTH_OR_EXPR
1699 || code == TRUTH_XOR_EXPR)
1700 extract_range_from_binary_expr (vr, expr);
1701 else if (TREE_CODE_CLASS (code) == tcc_unary)
1702 extract_range_from_unary_expr (vr, expr);
1703 else if (TREE_CODE_CLASS (code) == tcc_comparison)
1704 extract_range_from_comparison (vr, expr);
1705 else if (is_gimple_min_invariant (expr))
1706 set_value_range (vr, VR_RANGE, expr, expr, NULL);
1707 else if (vrp_expr_computes_nonzero (expr))
1708 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1710 set_value_range_to_varying (vr);
1713 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1714 would be profitable to adjust VR using scalar evolution information
1715 for VAR. If so, update VR with the new limits. */
1718 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
1721 tree init, step, chrec;
1722 bool init_is_max, unknown_max;
1724 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1725 better opportunities than a regular range, but I'm not sure. */
1726 if (vr->type == VR_ANTI_RANGE)
1729 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
1730 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
1733 init = initial_condition_in_loop_num (chrec, loop->num);
1734 step = evolution_part_in_loop_num (chrec, loop->num);
1736 /* If STEP is symbolic, we can't know whether INIT will be the
1737 minimum or maximum value in the range. */
1738 if (step == NULL_TREE
1739 || !is_gimple_min_invariant (step))
1742 /* Do not adjust ranges when chrec may wrap. */
1743 if (scev_probably_wraps_p (chrec_type (chrec), init, step, stmt,
1744 cfg_loops->parray[CHREC_VARIABLE (chrec)],
1745 &init_is_max, &unknown_max)
1749 if (!POINTER_TYPE_P (TREE_TYPE (init))
1750 && (vr->type == VR_VARYING || vr->type == VR_UNDEFINED))
1752 /* For VARYING or UNDEFINED ranges, just about anything we get
1753 from scalar evolutions should be better. */
1755 set_value_range (vr, VR_RANGE, TYPE_MIN_VALUE (TREE_TYPE (init)),
1758 set_value_range (vr, VR_RANGE, init, TYPE_MAX_VALUE (TREE_TYPE (init)),
1761 else if (vr->type == VR_RANGE)
1768 /* INIT is the maximum value. If INIT is lower than VR->MAX
1769 but no smaller than VR->MIN, set VR->MAX to INIT. */
1770 if (compare_values (init, max) == -1)
1774 /* If we just created an invalid range with the minimum
1775 greater than the maximum, take the minimum all the
1777 if (compare_values (min, max) == 1)
1778 min = TYPE_MIN_VALUE (TREE_TYPE (min));
1783 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
1784 if (compare_values (init, min) == 1)
1788 /* If we just created an invalid range with the minimum
1789 greater than the maximum, take the maximum all the
1791 if (compare_values (min, max) == 1)
1792 max = TYPE_MAX_VALUE (TREE_TYPE (max));
1796 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
1801 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
1803 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
1804 all the values in the ranges.
1806 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
1808 - Return NULL_TREE if it is not always possible to determine the
1809 value of the comparison. */
1813 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1)
1815 /* VARYING or UNDEFINED ranges cannot be compared. */
1816 if (vr0->type == VR_VARYING
1817 || vr0->type == VR_UNDEFINED
1818 || vr1->type == VR_VARYING
1819 || vr1->type == VR_UNDEFINED)
1822 /* Anti-ranges need to be handled separately. */
1823 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
1825 /* If both are anti-ranges, then we cannot compute any
1827 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
1830 /* These comparisons are never statically computable. */
1837 /* Equality can be computed only between a range and an
1838 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
1839 if (vr0->type == VR_RANGE)
1841 /* To simplify processing, make VR0 the anti-range. */
1842 value_range_t *tmp = vr0;
1847 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
1849 if (compare_values (vr0->min, vr1->min) == 0
1850 && compare_values (vr0->max, vr1->max) == 0)
1851 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
1856 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
1857 operands around and change the comparison code. */
1858 if (comp == GT_EXPR || comp == GE_EXPR)
1861 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
1867 if (comp == EQ_EXPR)
1869 /* Equality may only be computed if both ranges represent
1870 exactly one value. */
1871 if (compare_values (vr0->min, vr0->max) == 0
1872 && compare_values (vr1->min, vr1->max) == 0)
1874 int cmp_min = compare_values (vr0->min, vr1->min);
1875 int cmp_max = compare_values (vr0->max, vr1->max);
1876 if (cmp_min == 0 && cmp_max == 0)
1877 return boolean_true_node;
1878 else if (cmp_min != -2 && cmp_max != -2)
1879 return boolean_false_node;
1884 else if (comp == NE_EXPR)
1888 /* If VR0 is completely to the left or completely to the right
1889 of VR1, they are always different. Notice that we need to
1890 make sure that both comparisons yield similar results to
1891 avoid comparing values that cannot be compared at
1893 cmp1 = compare_values (vr0->max, vr1->min);
1894 cmp2 = compare_values (vr0->min, vr1->max);
1895 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
1896 return boolean_true_node;
1898 /* If VR0 and VR1 represent a single value and are identical,
1900 else if (compare_values (vr0->min, vr0->max) == 0
1901 && compare_values (vr1->min, vr1->max) == 0
1902 && compare_values (vr0->min, vr1->min) == 0
1903 && compare_values (vr0->max, vr1->max) == 0)
1904 return boolean_false_node;
1906 /* Otherwise, they may or may not be different. */
1910 else if (comp == LT_EXPR || comp == LE_EXPR)
1914 /* If VR0 is to the left of VR1, return true. */
1915 tst = compare_values (vr0->max, vr1->min);
1916 if ((comp == LT_EXPR && tst == -1)
1917 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
1918 return boolean_true_node;
1920 /* If VR0 is to the right of VR1, return false. */
1921 tst = compare_values (vr0->min, vr1->max);
1922 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
1923 || (comp == LE_EXPR && tst == 1))
1924 return boolean_false_node;
1926 /* Otherwise, we don't know. */
1934 /* Given a value range VR, a value VAL and a comparison code COMP, return
1935 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
1936 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
1937 always returns false. Return NULL_TREE if it is not always
1938 possible to determine the value of the comparison. */
1941 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val)
1943 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
1946 /* Anti-ranges need to be handled separately. */
1947 if (vr->type == VR_ANTI_RANGE)
1949 /* For anti-ranges, the only predicates that we can compute at
1950 compile time are equality and inequality. */
1957 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
1958 if (value_inside_range (val, vr) == 1)
1959 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
1964 if (comp == EQ_EXPR)
1966 /* EQ_EXPR may only be computed if VR represents exactly
1968 if (compare_values (vr->min, vr->max) == 0)
1970 int cmp = compare_values (vr->min, val);
1972 return boolean_true_node;
1973 else if (cmp == -1 || cmp == 1 || cmp == 2)
1974 return boolean_false_node;
1976 else if (compare_values (val, vr->min) == -1
1977 || compare_values (vr->max, val) == -1)
1978 return boolean_false_node;
1982 else if (comp == NE_EXPR)
1984 /* If VAL is not inside VR, then they are always different. */
1985 if (compare_values (vr->max, val) == -1
1986 || compare_values (vr->min, val) == 1)
1987 return boolean_true_node;
1989 /* If VR represents exactly one value equal to VAL, then return
1991 if (compare_values (vr->min, vr->max) == 0
1992 && compare_values (vr->min, val) == 0)
1993 return boolean_false_node;
1995 /* Otherwise, they may or may not be different. */
1998 else if (comp == LT_EXPR || comp == LE_EXPR)
2002 /* If VR is to the left of VAL, return true. */
2003 tst = compare_values (vr->max, val);
2004 if ((comp == LT_EXPR && tst == -1)
2005 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2006 return boolean_true_node;
2008 /* If VR is to the right of VAL, return false. */
2009 tst = compare_values (vr->min, val);
2010 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2011 || (comp == LE_EXPR && tst == 1))
2012 return boolean_false_node;
2014 /* Otherwise, we don't know. */
2017 else if (comp == GT_EXPR || comp == GE_EXPR)
2021 /* If VR is to the right of VAL, return true. */
2022 tst = compare_values (vr->min, val);
2023 if ((comp == GT_EXPR && tst == 1)
2024 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
2025 return boolean_true_node;
2027 /* If VR is to the left of VAL, return false. */
2028 tst = compare_values (vr->max, val);
2029 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
2030 || (comp == GE_EXPR && tst == -1))
2031 return boolean_false_node;
2033 /* Otherwise, we don't know. */
2041 /* Debugging dumps. */
2043 void dump_value_range (FILE *, value_range_t *);
2044 void debug_value_range (value_range_t *);
2045 void dump_all_value_ranges (FILE *);
2046 void debug_all_value_ranges (void);
2047 void dump_vr_equiv (FILE *, bitmap);
2048 void debug_vr_equiv (bitmap);
2051 /* Dump value range VR to FILE. */
2054 dump_value_range (FILE *file, value_range_t *vr)
2057 fprintf (file, "[]");
2058 else if (vr->type == VR_UNDEFINED)
2059 fprintf (file, "UNDEFINED");
2060 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
2062 tree type = TREE_TYPE (vr->min);
2064 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
2066 if (INTEGRAL_TYPE_P (type)
2067 && !TYPE_UNSIGNED (type)
2068 && vr->min == TYPE_MIN_VALUE (type))
2069 fprintf (file, "-INF");
2071 print_generic_expr (file, vr->min, 0);
2073 fprintf (file, ", ");
2075 if (INTEGRAL_TYPE_P (type)
2076 && vr->max == TYPE_MAX_VALUE (type))
2077 fprintf (file, "+INF");
2079 print_generic_expr (file, vr->max, 0);
2081 fprintf (file, "]");
2088 fprintf (file, " EQUIVALENCES: { ");
2090 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
2092 print_generic_expr (file, ssa_name (i), 0);
2093 fprintf (file, " ");
2097 fprintf (file, "} (%u elements)", c);
2100 else if (vr->type == VR_VARYING)
2101 fprintf (file, "VARYING");
2103 fprintf (file, "INVALID RANGE");
2107 /* Dump value range VR to stderr. */
2110 debug_value_range (value_range_t *vr)
2112 dump_value_range (stderr, vr);
2116 /* Dump value ranges of all SSA_NAMEs to FILE. */
2119 dump_all_value_ranges (FILE *file)
2123 for (i = 0; i < num_ssa_names; i++)
2127 print_generic_expr (file, ssa_name (i), 0);
2128 fprintf (file, ": ");
2129 dump_value_range (file, vr_value[i]);
2130 fprintf (file, "\n");
2134 fprintf (file, "\n");
2138 /* Dump all value ranges to stderr. */
2141 debug_all_value_ranges (void)
2143 dump_all_value_ranges (stderr);
2147 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
2148 create a new SSA name N and return the assertion assignment
2149 'V = ASSERT_EXPR <V, V OP W>'. */
2152 build_assert_expr_for (tree cond, tree v)
2156 gcc_assert (TREE_CODE (v) == SSA_NAME);
2157 n = duplicate_ssa_name (v, NULL_TREE);
2159 if (COMPARISON_CLASS_P (cond))
2161 tree a = build (ASSERT_EXPR, TREE_TYPE (v), v, cond);
2162 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, a);
2164 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
2166 /* Given !V, build the assignment N = false. */
2167 tree op0 = TREE_OPERAND (cond, 0);
2168 gcc_assert (op0 == v);
2169 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, boolean_false_node);
2171 else if (TREE_CODE (cond) == SSA_NAME)
2173 /* Given V, build the assignment N = true. */
2174 gcc_assert (v == cond);
2175 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, boolean_true_node);
2180 SSA_NAME_DEF_STMT (n) = assertion;
2182 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
2183 operand of the ASSERT_EXPR. Register the new name and the old one
2184 in the replacement table so that we can fix the SSA web after
2185 adding all the ASSERT_EXPRs. */
2186 register_new_name_mapping (n, v);
2192 /* Return false if EXPR is a predicate expression involving floating
2196 fp_predicate (tree expr)
2198 return (COMPARISON_CLASS_P (expr)
2199 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
2203 /* If the range of values taken by OP can be inferred after STMT executes,
2204 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2205 describes the inferred range. Return true if a range could be
2209 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
2212 *comp_code_p = ERROR_MARK;
2214 /* Do not attempt to infer anything in names that flow through
2216 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
2219 /* Similarly, don't infer anything from statements that may throw
2221 if (tree_could_throw_p (stmt))
2224 /* If STMT is the last statement of a basic block with no
2225 successors, there is no point inferring anything about any of its
2226 operands. We would not be able to find a proper insertion point
2227 for the assertion, anyway. */
2228 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
2231 if (POINTER_TYPE_P (TREE_TYPE (op)))
2234 unsigned num_uses, num_derefs;
2236 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
2237 if (num_derefs > 0 && flag_delete_null_pointer_checks)
2239 /* We can only assume that a pointer dereference will yield
2240 non-NULL if -fdelete-null-pointer-checks is enabled. */
2241 *val_p = build_int_cst (TREE_TYPE (op), 0);
2242 *comp_code_p = NE_EXPR;
2251 void dump_asserts_for (FILE *, tree);
2252 void debug_asserts_for (tree);
2253 void dump_all_asserts (FILE *);
2254 void debug_all_asserts (void);
2256 /* Dump all the registered assertions for NAME to FILE. */
2259 dump_asserts_for (FILE *file, tree name)
2263 fprintf (file, "Assertions to be inserted for ");
2264 print_generic_expr (file, name, 0);
2265 fprintf (file, "\n");
2267 loc = asserts_for[SSA_NAME_VERSION (name)];
2270 fprintf (file, "\t");
2271 print_generic_expr (file, bsi_stmt (loc->si), 0);
2272 fprintf (file, "\n\tBB #%d", loc->bb->index);
2275 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
2276 loc->e->dest->index);
2277 dump_edge_info (file, loc->e, 0);
2279 fprintf (file, "\n\tPREDICATE: ");
2280 print_generic_expr (file, name, 0);
2281 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
2282 print_generic_expr (file, loc->val, 0);
2283 fprintf (file, "\n\n");
2287 fprintf (file, "\n");
2291 /* Dump all the registered assertions for NAME to stderr. */
2294 debug_asserts_for (tree name)
2296 dump_asserts_for (stderr, name);
2300 /* Dump all the registered assertions for all the names to FILE. */
2303 dump_all_asserts (FILE *file)
2308 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
2309 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2310 dump_asserts_for (file, ssa_name (i));
2311 fprintf (file, "\n");
2315 /* Dump all the registered assertions for all the names to stderr. */
2318 debug_all_asserts (void)
2320 dump_all_asserts (stderr);
2324 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2325 'NAME COMP_CODE VAL' at a location that dominates block BB or
2326 E->DEST, then register this location as a possible insertion point
2327 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2329 BB, E and SI provide the exact insertion point for the new
2330 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2331 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2332 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2333 must not be NULL. */
2336 register_new_assert_for (tree name,
2337 enum tree_code comp_code,
2341 block_stmt_iterator si)
2343 assert_locus_t n, loc, last_loc;
2345 basic_block dest_bb;
2347 #if defined ENABLE_CHECKING
2348 gcc_assert (bb == NULL || e == NULL);
2351 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
2352 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
2355 /* The new assertion A will be inserted at BB or E. We need to
2356 determine if the new location is dominated by a previously
2357 registered location for A. If we are doing an edge insertion,
2358 assume that A will be inserted at E->DEST. Note that this is not
2361 If E is a critical edge, it will be split. But even if E is
2362 split, the new block will dominate the same set of blocks that
2365 The reverse, however, is not true, blocks dominated by E->DEST
2366 will not be dominated by the new block created to split E. So,
2367 if the insertion location is on a critical edge, we will not use
2368 the new location to move another assertion previously registered
2369 at a block dominated by E->DEST. */
2370 dest_bb = (bb) ? bb : e->dest;
2372 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2373 VAL at a block dominating DEST_BB, then we don't need to insert a new
2374 one. Similarly, if the same assertion already exists at a block
2375 dominated by DEST_BB and the new location is not on a critical
2376 edge, then update the existing location for the assertion (i.e.,
2377 move the assertion up in the dominance tree).
2379 Note, this is implemented as a simple linked list because there
2380 should not be more than a handful of assertions registered per
2381 name. If this becomes a performance problem, a table hashed by
2382 COMP_CODE and VAL could be implemented. */
2383 loc = asserts_for[SSA_NAME_VERSION (name)];
2388 if (loc->comp_code == comp_code
2390 || operand_equal_p (loc->val, val, 0)))
2392 /* If the assertion NAME COMP_CODE VAL has already been
2393 registered at a basic block that dominates DEST_BB, then
2394 we don't need to insert the same assertion again. Note
2395 that we don't check strict dominance here to avoid
2396 replicating the same assertion inside the same basic
2397 block more than once (e.g., when a pointer is
2398 dereferenced several times inside a block).
2400 An exception to this rule are edge insertions. If the
2401 new assertion is to be inserted on edge E, then it will
2402 dominate all the other insertions that we may want to
2403 insert in DEST_BB. So, if we are doing an edge
2404 insertion, don't do this dominance check. */
2406 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
2409 /* Otherwise, if E is not a critical edge and DEST_BB
2410 dominates the existing location for the assertion, move
2411 the assertion up in the dominance tree by updating its
2412 location information. */
2413 if ((e == NULL || !EDGE_CRITICAL_P (e))
2414 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
2423 /* Update the last node of the list and move to the next one. */
2428 /* If we didn't find an assertion already registered for
2429 NAME COMP_CODE VAL, add a new one at the end of the list of
2430 assertions associated with NAME. */
2431 n = xmalloc (sizeof (*n));
2435 n->comp_code = comp_code;
2442 asserts_for[SSA_NAME_VERSION (name)] = n;
2444 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
2448 /* Try to register an edge assertion for SSA name NAME on edge E for
2449 the conditional jump pointed to by SI. Return true if an assertion
2450 for NAME could be registered. */
2453 register_edge_assert_for (tree name, edge e, block_stmt_iterator si)
2456 enum tree_code comp_code;
2458 stmt = bsi_stmt (si);
2460 /* Do not attempt to infer anything in names that flow through
2462 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
2465 /* If NAME was not found in the sub-graph reachable from E, then
2466 there's nothing to do. */
2467 if (!TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
2470 /* We found a use of NAME in the sub-graph rooted at E->DEST.
2471 Register an assertion for NAME according to the value that NAME
2473 if (TREE_CODE (stmt) == COND_EXPR)
2475 /* If BB ends in a COND_EXPR then NAME then we should insert
2476 the original predicate on EDGE_TRUE_VALUE and the
2477 opposite predicate on EDGE_FALSE_VALUE. */
2478 tree cond = COND_EXPR_COND (stmt);
2479 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
2481 /* Predicates may be a single SSA name or NAME OP VAL. */
2484 /* If the predicate is a name, it must be NAME, in which
2485 case we create the predicate NAME == true or
2486 NAME == false accordingly. */
2487 comp_code = EQ_EXPR;
2488 val = (is_else_edge) ? boolean_false_node : boolean_true_node;
2492 /* Otherwise, we have a comparison of the form NAME COMP VAL
2493 or VAL COMP NAME. */
2494 if (name == TREE_OPERAND (cond, 1))
2496 /* If the predicate is of the form VAL COMP NAME, flip
2497 COMP around because we need to register NAME as the
2498 first operand in the predicate. */
2499 comp_code = swap_tree_comparison (TREE_CODE (cond));
2500 val = TREE_OPERAND (cond, 0);
2504 /* The comparison is of the form NAME COMP VAL, so the
2505 comparison code remains unchanged. */
2506 comp_code = TREE_CODE (cond);
2507 val = TREE_OPERAND (cond, 1);
2510 /* If we are inserting the assertion on the ELSE edge, we
2511 need to invert the sign comparison. */
2513 comp_code = invert_tree_comparison (comp_code, 0);
2515 /* Do not register always-false predicates. FIXME, this
2516 works around a limitation in fold() when dealing with
2517 enumerations. Given 'enum { N1, N2 } x;', fold will not
2518 fold 'if (x > N2)' to 'if (0)'. */
2519 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
2520 && (INTEGRAL_TYPE_P (TREE_TYPE (val))
2521 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (val))))
2523 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
2524 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
2526 if (comp_code == GT_EXPR && compare_values (val, max) == 0)
2529 if (comp_code == LT_EXPR && compare_values (val, min) == 0)
2536 /* FIXME. Handle SWITCH_EXPR. */
2540 register_new_assert_for (name, comp_code, val, NULL, e, si);
2545 static bool find_assert_locations (basic_block bb);
2547 /* Determine whether the outgoing edges of BB should receive an
2548 ASSERT_EXPR for each of the operands of BB's last statement. The
2549 last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2551 If any of the sub-graphs rooted at BB have an interesting use of
2552 the predicate operands, an assert location node is added to the
2553 list of assertions for the corresponding operands. */
2556 find_conditional_asserts (basic_block bb)
2559 block_stmt_iterator last_si;
2565 need_assert = false;
2566 last_si = bsi_last (bb);
2567 last = bsi_stmt (last_si);
2569 /* Look for uses of the operands in each of the sub-graphs
2570 rooted at BB. We need to check each of the outgoing edges
2571 separately, so that we know what kind of ASSERT_EXPR to
2573 FOR_EACH_EDGE (e, ei, bb->succs)
2578 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
2579 Otherwise, when we finish traversing each of the sub-graphs, we
2580 won't know whether the variables were found in the sub-graphs or
2581 if they had been found in a block upstream from BB. */
2582 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2583 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2585 /* Traverse the strictly dominated sub-graph rooted at E->DEST
2586 to determine if any of the operands in the conditional
2587 predicate are used. */
2589 need_assert |= find_assert_locations (e->dest);
2591 /* Register the necessary assertions for each operand in the
2592 conditional predicate. */
2593 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2594 need_assert |= register_edge_assert_for (op, e, last_si);
2597 /* Finally, indicate that we have found the operands in the
2599 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2600 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2606 /* Traverse all the statements in block BB looking for statements that
2607 may generate useful assertions for the SSA names in their operand.
2608 If a statement produces a useful assertion A for name N_i, then the
2609 list of assertions already generated for N_i is scanned to
2610 determine if A is actually needed.
2612 If N_i already had the assertion A at a location dominating the
2613 current location, then nothing needs to be done. Otherwise, the
2614 new location for A is recorded instead.
2616 1- For every statement S in BB, all the variables used by S are
2617 added to bitmap FOUND_IN_SUBGRAPH.
2619 2- If statement S uses an operand N in a way that exposes a known
2620 value range for N, then if N was not already generated by an
2621 ASSERT_EXPR, create a new assert location for N. For instance,
2622 if N is a pointer and the statement dereferences it, we can
2623 assume that N is not NULL.
2625 3- COND_EXPRs are a special case of #2. We can derive range
2626 information from the predicate but need to insert different
2627 ASSERT_EXPRs for each of the sub-graphs rooted at the
2628 conditional block. If the last statement of BB is a conditional
2629 expression of the form 'X op Y', then
2631 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
2633 b) If the conditional is the only entry point to the sub-graph
2634 corresponding to the THEN_CLAUSE, recurse into it. On
2635 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
2636 an ASSERT_EXPR is added for the corresponding variable.
2638 c) Repeat step (b) on the ELSE_CLAUSE.
2640 d) Mark X and Y in FOUND_IN_SUBGRAPH.
2649 In this case, an assertion on the THEN clause is useful to
2650 determine that 'a' is always 9 on that edge. However, an assertion
2651 on the ELSE clause would be unnecessary.
2653 4- If BB does not end in a conditional expression, then we recurse
2654 into BB's dominator children.
2656 At the end of the recursive traversal, every SSA name will have a
2657 list of locations where ASSERT_EXPRs should be added. When a new
2658 location for name N is found, it is registered by calling
2659 register_new_assert_for. That function keeps track of all the
2660 registered assertions to prevent adding unnecessary assertions.
2661 For instance, if a pointer P_4 is dereferenced more than once in a
2662 dominator tree, only the location dominating all the dereference of
2663 P_4 will receive an ASSERT_EXPR.
2665 If this function returns true, then it means that there are names
2666 for which we need to generate ASSERT_EXPRs. Those assertions are
2667 inserted by process_assert_insertions.
2669 TODO. Handle SWITCH_EXPR. */
2672 find_assert_locations (basic_block bb)
2674 block_stmt_iterator si;
2679 if (TEST_BIT (blocks_visited, bb->index))
2682 SET_BIT (blocks_visited, bb->index);
2684 need_assert = false;
2686 /* Traverse all PHI nodes in BB marking used operands. */
2687 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
2689 use_operand_p arg_p;
2692 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
2694 tree arg = USE_FROM_PTR (arg_p);
2695 if (TREE_CODE (arg) == SSA_NAME)
2697 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
2698 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
2703 /* Traverse all the statements in BB marking used names and looking
2704 for statements that may infer assertions for their used operands. */
2706 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
2711 stmt = bsi_stmt (si);
2713 /* See if we can derive an assertion for any of STMT's operands. */
2714 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
2717 enum tree_code comp_code;
2719 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
2720 the sub-graph of a conditional block, when we return from
2721 this recursive walk, our parent will use the
2722 FOUND_IN_SUBGRAPH bitset to determine if one of the
2723 operands it was looking for was present in the sub-graph. */
2724 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2726 /* If OP is used only once, namely in this STMT, don't
2727 bother creating an ASSERT_EXPR for it. Such an
2728 ASSERT_EXPR would do nothing but increase compile time.
2729 Experiments show that with this simple check, we can save
2730 more than 20% of ASSERT_EXPRs. */
2731 if (has_single_use (op))
2734 /* If OP is used in such a way that we can infer a value
2735 range for it, and we don't find a previous assertion for
2736 it, create a new assertion location node for OP. */
2737 if (infer_value_range (stmt, op, &comp_code, &value))
2739 register_new_assert_for (op, comp_code, value, bb, NULL, si);
2744 /* Remember the last statement of the block. */
2748 /* If BB's last statement is a conditional expression
2749 involving integer operands, recurse into each of the sub-graphs
2750 rooted at BB to determine if we need to add ASSERT_EXPRs. */
2752 && TREE_CODE (last) == COND_EXPR
2753 && !fp_predicate (COND_EXPR_COND (last))
2754 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
2755 need_assert |= find_conditional_asserts (bb);
2757 /* Recurse into the dominator children of BB. */
2758 for (son = first_dom_son (CDI_DOMINATORS, bb);
2760 son = next_dom_son (CDI_DOMINATORS, son))
2761 need_assert |= find_assert_locations (son);
2767 /* Create an ASSERT_EXPR for NAME and insert it in the location
2768 indicated by LOC. Return true if we made any edge insertions. */
2771 process_assert_insertions_for (tree name, assert_locus_t loc)
2773 /* Build the comparison expression NAME_i COMP_CODE VAL. */
2774 tree stmt, cond, assert_expr;
2778 cond = build (loc->comp_code, boolean_type_node, name, loc->val);
2779 assert_expr = build_assert_expr_for (cond, name);
2783 /* We have been asked to insert the assertion on an edge. This
2784 is used only by COND_EXPR and SWITCH_EXPR assertions. */
2785 #if defined ENABLE_CHECKING
2786 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
2787 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
2790 bsi_insert_on_edge (loc->e, assert_expr);
2794 /* Otherwise, we can insert right after LOC->SI iff the
2795 statement must not be the last statement in the block. */
2796 stmt = bsi_stmt (loc->si);
2797 if (!stmt_ends_bb_p (stmt))
2799 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
2803 /* If STMT must be the last statement in BB, we can only insert new
2804 assertions on the non-abnormal edge out of BB. Note that since
2805 STMT is not control flow, there may only be one non-abnormal edge
2807 FOR_EACH_EDGE (e, ei, loc->bb->succs)
2808 if (!(e->flags & EDGE_ABNORMAL))
2810 bsi_insert_on_edge (e, assert_expr);
2818 /* Process all the insertions registered for every name N_i registered
2819 in NEED_ASSERT_FOR. The list of assertions to be inserted are
2820 found in ASSERTS_FOR[i]. */
2823 process_assert_insertions (void)
2827 bool update_edges_p = false;
2828 int num_asserts = 0;
2830 if (dump_file && (dump_flags & TDF_DETAILS))
2831 dump_all_asserts (dump_file);
2833 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2835 assert_locus_t loc = asserts_for[i];
2840 assert_locus_t next = loc->next;
2841 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
2849 bsi_commit_edge_inserts ();
2851 if (dump_file && (dump_flags & TDF_STATS))
2852 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
2857 /* Traverse the flowgraph looking for conditional jumps to insert range
2858 expressions. These range expressions are meant to provide information
2859 to optimizations that need to reason in terms of value ranges. They
2860 will not be expanded into RTL. For instance, given:
2869 this pass will transform the code into:
2875 x = ASSERT_EXPR <x, x < y>
2880 y = ASSERT_EXPR <y, x <= y>
2884 The idea is that once copy and constant propagation have run, other
2885 optimizations will be able to determine what ranges of values can 'x'
2886 take in different paths of the code, simply by checking the reaching
2887 definition of 'x'. */
2890 insert_range_assertions (void)
2896 found_in_subgraph = sbitmap_alloc (num_ssa_names);
2897 sbitmap_zero (found_in_subgraph);
2899 blocks_visited = sbitmap_alloc (last_basic_block);
2900 sbitmap_zero (blocks_visited);
2902 need_assert_for = BITMAP_ALLOC (NULL);
2903 asserts_for = xmalloc (num_ssa_names * sizeof (assert_locus_t));
2904 memset (asserts_for, 0, num_ssa_names * sizeof (assert_locus_t));
2906 calculate_dominance_info (CDI_DOMINATORS);
2908 update_ssa_p = false;
2909 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2910 if (find_assert_locations (e->dest))
2911 update_ssa_p = true;
2915 process_assert_insertions ();
2916 update_ssa (TODO_update_ssa_no_phi);
2919 if (dump_file && (dump_flags & TDF_DETAILS))
2921 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
2922 dump_function_to_file (current_function_decl, dump_file, dump_flags);
2925 sbitmap_free (found_in_subgraph);
2927 BITMAP_FREE (need_assert_for);
2931 /* Convert range assertion expressions into the implied copies and
2932 copy propagate away the copies. Doing the trivial copy propagation
2933 here avoids the need to run the full copy propagation pass after
2936 FIXME, this will eventually lead to copy propagation removing the
2937 names that had useful range information attached to them. For
2938 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
2939 then N_i will have the range [3, +INF].
2941 However, by converting the assertion into the implied copy
2942 operation N_i = N_j, we will then copy-propagate N_j into the uses
2943 of N_i and lose the range information. We may want to hold on to
2944 ASSERT_EXPRs a little while longer as the ranges could be used in
2945 things like jump threading.
2947 The problem with keeping ASSERT_EXPRs around is that passes after
2948 VRP need to handle them appropriately.
2950 Another approach would be to make the range information a first
2951 class property of the SSA_NAME so that it can be queried from
2952 any pass. This is made somewhat more complex by the need for
2953 multiple ranges to be associated with one SSA_NAME. */
2956 remove_range_assertions (void)
2959 block_stmt_iterator si;
2961 /* Note that the BSI iterator bump happens at the bottom of the
2962 loop and no bump is necessary if we're removing the statement
2963 referenced by the current BSI. */
2965 for (si = bsi_start (bb); !bsi_end_p (si);)
2967 tree stmt = bsi_stmt (si);
2969 if (TREE_CODE (stmt) == MODIFY_EXPR
2970 && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
2972 tree rhs = TREE_OPERAND (stmt, 1);
2973 tree cond = fold (ASSERT_EXPR_COND (rhs));
2974 use_operand_p use_p;
2975 imm_use_iterator iter;
2977 gcc_assert (cond != boolean_false_node);
2978 TREE_OPERAND (stmt, 1) = ASSERT_EXPR_VAR (rhs);
2981 /* The statement is now a copy. Propagate the RHS into
2982 every use of the LHS. */
2983 FOR_EACH_IMM_USE_SAFE (use_p, iter, TREE_OPERAND (stmt, 0))
2985 SET_USE (use_p, ASSERT_EXPR_VAR (rhs));
2986 update_stmt (USE_STMT (use_p));
2989 /* And finally, remove the copy, it is not needed. */
2996 sbitmap_free (blocks_visited);
3000 /* Return true if STMT is interesting for VRP. */
3003 stmt_interesting_for_vrp (tree stmt)
3005 if (TREE_CODE (stmt) == PHI_NODE
3006 && is_gimple_reg (PHI_RESULT (stmt))
3007 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
3008 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
3010 else if (TREE_CODE (stmt) == MODIFY_EXPR)
3012 tree lhs = TREE_OPERAND (stmt, 0);
3014 if (TREE_CODE (lhs) == SSA_NAME
3015 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3016 || POINTER_TYPE_P (TREE_TYPE (lhs)))
3017 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3020 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3027 /* Initialize local data structures for VRP. */
3030 vrp_initialize (void)
3034 vr_value = xmalloc (num_ssa_names * sizeof (value_range_t *));
3035 memset (vr_value, 0, num_ssa_names * sizeof (value_range_t *));
3039 block_stmt_iterator si;
3042 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3044 if (!stmt_interesting_for_vrp (phi))
3046 tree lhs = PHI_RESULT (phi);
3047 set_value_range_to_varying (get_value_range (lhs));
3048 DONT_SIMULATE_AGAIN (phi) = true;
3051 DONT_SIMULATE_AGAIN (phi) = false;
3054 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3056 tree stmt = bsi_stmt (si);
3058 if (!stmt_interesting_for_vrp (stmt))
3062 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
3063 set_value_range_to_varying (get_value_range (def));
3064 DONT_SIMULATE_AGAIN (stmt) = true;
3068 DONT_SIMULATE_AGAIN (stmt) = false;
3075 /* Visit assignment STMT. If it produces an interesting range, record
3076 the SSA name in *OUTPUT_P. */
3078 static enum ssa_prop_result
3079 vrp_visit_assignment (tree stmt, tree *output_p)
3084 lhs = TREE_OPERAND (stmt, 0);
3085 rhs = TREE_OPERAND (stmt, 1);
3087 /* We only keep track of ranges in integral and pointer types. */
3088 if (TREE_CODE (lhs) == SSA_NAME
3089 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3090 || POINTER_TYPE_P (TREE_TYPE (lhs))))
3093 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3095 extract_range_from_expr (&new_vr, rhs);
3097 /* If STMT is inside a loop, we may be able to know something
3098 else about the range of LHS by examining scalar evolution
3100 if (cfg_loops && (l = loop_containing_stmt (stmt)))
3101 adjust_range_with_scev (&new_vr, l, stmt, lhs);
3103 if (update_value_range (lhs, &new_vr))
3107 if (dump_file && (dump_flags & TDF_DETAILS))
3109 fprintf (dump_file, "Found new range for ");
3110 print_generic_expr (dump_file, lhs, 0);
3111 fprintf (dump_file, ": ");
3112 dump_value_range (dump_file, &new_vr);
3113 fprintf (dump_file, "\n\n");
3116 if (new_vr.type == VR_VARYING)
3117 return SSA_PROP_VARYING;
3119 return SSA_PROP_INTERESTING;
3122 return SSA_PROP_NOT_INTERESTING;
3125 /* Every other statement produces no useful ranges. */
3126 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3127 set_value_range_to_varying (get_value_range (def));
3129 return SSA_PROP_VARYING;
3133 /* Compare all the value ranges for names equivalent to VAR with VAL
3134 using comparison code COMP. Return the same value returned by
3135 compare_range_with_value. */
3138 compare_name_with_value (enum tree_code comp, tree var, tree val)
3145 t = retval = NULL_TREE;
3147 /* Get the set of equivalences for VAR. */
3148 e = get_value_range (var)->equiv;
3150 /* Add VAR to its own set of equivalences so that VAR's value range
3151 is processed by this loop (otherwise, we would have to replicate
3152 the body of the loop just to check VAR's value range). */
3153 bitmap_set_bit (e, SSA_NAME_VERSION (var));
3155 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
3157 value_range_t equiv_vr = *(vr_value[i]);
3159 /* If name N_i does not have a valid range, use N_i as its own
3160 range. This allows us to compare against names that may
3161 have N_i in their ranges. */
3162 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
3164 equiv_vr.type = VR_RANGE;
3165 equiv_vr.min = ssa_name (i);
3166 equiv_vr.max = ssa_name (i);
3169 t = compare_range_with_value (comp, &equiv_vr, val);
3172 /* All the ranges should compare the same against VAL. */
3173 gcc_assert (retval == NULL || t == retval);
3178 /* Remove VAR from its own equivalence set. */
3179 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
3184 /* We couldn't find a non-NULL value for the predicate. */
3189 /* Given a comparison code COMP and names N1 and N2, compare all the
3190 ranges equivalent to N1 against all the ranges equivalent to N2
3191 to determine the value of N1 COMP N2. Return the same value
3192 returned by compare_ranges. */
3195 compare_names (enum tree_code comp, tree n1, tree n2)
3199 bitmap_iterator bi1, bi2;
3202 /* Compare the ranges of every name equivalent to N1 against the
3203 ranges of every name equivalent to N2. */
3204 e1 = get_value_range (n1)->equiv;
3205 e2 = get_value_range (n2)->equiv;
3207 /* Add N1 and N2 to their own set of equivalences to avoid
3208 duplicating the body of the loop just to check N1 and N2
3210 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
3211 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
3213 /* If the equivalence sets have a common intersection, then the two
3214 names can be compared without checking their ranges. */
3215 if (bitmap_intersect_p (e1, e2))
3217 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3218 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3220 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
3222 : boolean_false_node;
3225 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3226 N2 to their own set of equivalences to avoid duplicating the body
3227 of the loop just to check N1 and N2 ranges. */
3228 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
3230 value_range_t vr1 = *(vr_value[i1]);
3232 /* If the range is VARYING or UNDEFINED, use the name itself. */
3233 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
3235 vr1.type = VR_RANGE;
3236 vr1.min = ssa_name (i1);
3237 vr1.max = ssa_name (i1);
3240 t = retval = NULL_TREE;
3241 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
3243 value_range_t vr2 = *(vr_value[i2]);
3245 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
3247 vr2.type = VR_RANGE;
3248 vr2.min = ssa_name (i2);
3249 vr2.max = ssa_name (i2);
3252 t = compare_ranges (comp, &vr1, &vr2);
3255 /* All the ranges in the equivalent sets should compare
3257 gcc_assert (retval == NULL || t == retval);
3264 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3265 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3270 /* None of the equivalent ranges are useful in computing this
3272 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3273 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3278 /* Given a conditional predicate COND, try to determine if COND yields
3279 true or false based on the value ranges of its operands. Return
3280 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3281 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3282 NULL if the conditional cannot be evaluated at compile time.
3284 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3285 the operands in COND are used when trying to compute its value.
3286 This is only used during final substitution. During propagation,
3287 we only check the range of each variable and not its equivalents. */
3290 vrp_evaluate_conditional (tree cond, bool use_equiv_p)
3292 gcc_assert (TREE_CODE (cond) == SSA_NAME
3293 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
3295 if (TREE_CODE (cond) == SSA_NAME)
3301 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node);
3304 value_range_t *vr = get_value_range (cond);
3305 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node);
3308 /* If COND has a known boolean range, return it. */
3312 /* Otherwise, if COND has a symbolic range of exactly one value,
3314 vr = get_value_range (cond);
3315 if (vr->type == VR_RANGE && vr->min == vr->max)
3320 tree op0 = TREE_OPERAND (cond, 0);
3321 tree op1 = TREE_OPERAND (cond, 1);
3323 /* We only deal with integral and pointer types. */
3324 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
3325 && !POINTER_TYPE_P (TREE_TYPE (op0)))
3330 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
3331 return compare_names (TREE_CODE (cond), op0, op1);
3332 else if (TREE_CODE (op0) == SSA_NAME)
3333 return compare_name_with_value (TREE_CODE (cond), op0, op1);
3334 else if (TREE_CODE (op1) == SSA_NAME)
3335 return compare_name_with_value (
3336 swap_tree_comparison (TREE_CODE (cond)), op1, op0);
3340 value_range_t *vr0, *vr1;
3342 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
3343 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
3346 return compare_ranges (TREE_CODE (cond), vr0, vr1);
3347 else if (vr0 && vr1 == NULL)
3348 return compare_range_with_value (TREE_CODE (cond), vr0, op1);
3349 else if (vr0 == NULL && vr1)
3350 return compare_range_with_value (
3351 swap_tree_comparison (TREE_CODE (cond)), vr1, op0);
3355 /* Anything else cannot be computed statically. */
3360 /* Visit conditional statement STMT. If we can determine which edge
3361 will be taken out of STMT's basic block, record it in
3362 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3363 SSA_PROP_VARYING. */
3365 static enum ssa_prop_result
3366 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
3370 *taken_edge_p = NULL;
3372 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3373 add ASSERT_EXPRs for them. */
3374 if (TREE_CODE (stmt) == SWITCH_EXPR)
3375 return SSA_PROP_VARYING;
3377 cond = COND_EXPR_COND (stmt);
3379 if (dump_file && (dump_flags & TDF_DETAILS))
3384 fprintf (dump_file, "\nVisiting conditional with predicate: ");
3385 print_generic_expr (dump_file, cond, 0);
3386 fprintf (dump_file, "\nWith known ranges\n");
3388 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
3390 fprintf (dump_file, "\t");
3391 print_generic_expr (dump_file, use, 0);
3392 fprintf (dump_file, ": ");
3393 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
3396 fprintf (dump_file, "\n");
3399 /* Compute the value of the predicate COND by checking the known
3400 ranges of each of its operands.
3402 Note that we cannot evaluate all the equivalent ranges here
3403 because those ranges may not yet be final and with the current
3404 propagation strategy, we cannot determine when the value ranges
3405 of the names in the equivalence set have changed.
3407 For instance, given the following code fragment
3411 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3415 Assume that on the first visit to i_14, i_5 has the temporary
3416 range [8, 8] because the second argument to the PHI function is
3417 not yet executable. We derive the range ~[0, 0] for i_14 and the
3418 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3419 the first time, since i_14 is equivalent to the range [8, 8], we
3420 determine that the predicate is always false.
3422 On the next round of propagation, i_13 is determined to be
3423 VARYING, which causes i_5 to drop down to VARYING. So, another
3424 visit to i_14 is scheduled. In this second visit, we compute the
3425 exact same range and equivalence set for i_14, namely ~[0, 0] and
3426 { i_5 }. But we did not have the previous range for i_5
3427 registered, so vrp_visit_assignment thinks that the range for
3428 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3429 is not visited again, which stops propagation from visiting
3430 statements in the THEN clause of that if().
3432 To properly fix this we would need to keep the previous range
3433 value for the names in the equivalence set. This way we would've
3434 discovered that from one visit to the other i_5 changed from
3435 range [8, 8] to VR_VARYING.
3437 However, fixing this apparent limitation may not be worth the
3438 additional checking. Testing on several code bases (GCC, DLV,
3439 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3440 4 more predicates folded in SPEC. */
3441 val = vrp_evaluate_conditional (cond, false);
3443 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
3445 if (dump_file && (dump_flags & TDF_DETAILS))
3447 fprintf (dump_file, "\nPredicate evaluates to: ");
3448 if (val == NULL_TREE)
3449 fprintf (dump_file, "DON'T KNOW\n");
3451 print_generic_stmt (dump_file, val, 0);
3454 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
3458 /* Evaluate statement STMT. If the statement produces a useful range,
3459 return SSA_PROP_INTERESTING and record the SSA name with the
3460 interesting range into *OUTPUT_P.
3462 If STMT is a conditional branch and we can determine its truth
3463 value, the taken edge is recorded in *TAKEN_EDGE_P.
3465 If STMT produces a varying value, return SSA_PROP_VARYING. */
3467 static enum ssa_prop_result
3468 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
3474 if (dump_file && (dump_flags & TDF_DETAILS))
3476 fprintf (dump_file, "\nVisiting statement:\n");
3477 print_generic_stmt (dump_file, stmt, dump_flags);
3478 fprintf (dump_file, "\n");
3481 ann = stmt_ann (stmt);
3482 if (TREE_CODE (stmt) == MODIFY_EXPR
3483 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3484 return vrp_visit_assignment (stmt, output_p);
3485 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3486 return vrp_visit_cond_stmt (stmt, taken_edge_p);
3488 /* All other statements produce nothing of interest for VRP, so mark
3489 their outputs varying and prevent further simulation. */
3490 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3491 set_value_range_to_varying (get_value_range (def));
3493 return SSA_PROP_VARYING;
3497 /* Meet operation for value ranges. Given two value ranges VR0 and
3498 VR1, store in VR0 the result of meeting VR0 and VR1.
3500 The meeting rules are as follows:
3502 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
3504 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
3505 union of VR0 and VR1. */
3508 vrp_meet (value_range_t *vr0, value_range_t *vr1)
3510 if (vr0->type == VR_UNDEFINED)
3512 copy_value_range (vr0, vr1);
3516 if (vr1->type == VR_UNDEFINED)
3518 /* Nothing to do. VR0 already has the resulting range. */
3522 if (vr0->type == VR_VARYING)
3524 /* Nothing to do. VR0 already has the resulting range. */
3528 if (vr1->type == VR_VARYING)
3530 set_value_range_to_varying (vr0);
3534 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
3536 /* If VR0 and VR1 have a non-empty intersection, compute the
3537 union of both ranges. */
3538 if (value_ranges_intersect_p (vr0, vr1))
3543 /* The lower limit of the new range is the minimum of the
3544 two ranges. If they cannot be compared, the result is
3546 cmp = compare_values (vr0->min, vr1->min);
3547 if (cmp == 0 || cmp == 1)
3553 set_value_range_to_varying (vr0);
3557 /* Similarly, the upper limit of the new range is the
3558 maximum of the two ranges. If they cannot be compared,
3559 the result is VARYING. */
3560 cmp = compare_values (vr0->max, vr1->max);
3561 if (cmp == 0 || cmp == -1)
3567 set_value_range_to_varying (vr0);
3571 /* The resulting set of equivalences is the intersection of
3573 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3574 bitmap_and_into (vr0->equiv, vr1->equiv);
3575 else if (vr0->equiv && !vr1->equiv)
3576 bitmap_clear (vr0->equiv);
3578 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
3583 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
3585 /* Two anti-ranges meet only if they are both identical. */
3586 if (compare_values (vr0->min, vr1->min) == 0
3587 && compare_values (vr0->max, vr1->max) == 0
3588 && compare_values (vr0->min, vr0->max) == 0)
3590 /* The resulting set of equivalences is the intersection of
3592 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3593 bitmap_and_into (vr0->equiv, vr1->equiv);
3594 else if (vr0->equiv && !vr1->equiv)
3595 bitmap_clear (vr0->equiv);
3600 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
3602 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
3603 meet only if the ranges have an empty intersection. The
3604 result of the meet operation is the anti-range. */
3605 if (!symbolic_range_p (vr0)
3606 && !symbolic_range_p (vr1)
3607 && !value_ranges_intersect_p (vr0, vr1))
3609 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
3610 set. We need to compute the intersection of the two
3611 equivalence sets. */
3612 if (vr1->type == VR_ANTI_RANGE)
3613 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
3615 /* The resulting set of equivalences is the intersection of
3617 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3618 bitmap_and_into (vr0->equiv, vr1->equiv);
3619 else if (vr0->equiv && !vr1->equiv)
3620 bitmap_clear (vr0->equiv);
3631 /* The two range VR0 and VR1 do not meet. Before giving up and
3632 setting the result to VARYING, see if we can at least derive a
3633 useful anti-range. FIXME, all this nonsense about distinguishing
3634 anti-ranges from ranges is necessary because of the odd
3635 semantics of range_includes_zero_p and friends. */
3636 if (!symbolic_range_p (vr0)
3637 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
3638 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
3639 && !symbolic_range_p (vr1)
3640 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
3641 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
3643 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
3645 /* Since this meet operation did not result from the meeting of
3646 two equivalent names, VR0 cannot have any equivalences. */
3648 bitmap_clear (vr0->equiv);
3651 set_value_range_to_varying (vr0);
3655 /* Visit all arguments for PHI node PHI that flow through executable
3656 edges. If a valid value range can be derived from all the incoming
3657 value ranges, set a new range for the LHS of PHI. */
3659 static enum ssa_prop_result
3660 vrp_visit_phi_node (tree phi)
3663 tree lhs = PHI_RESULT (phi);
3664 value_range_t *lhs_vr = get_value_range (lhs);
3665 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3667 copy_value_range (&vr_result, lhs_vr);
3669 if (dump_file && (dump_flags & TDF_DETAILS))
3671 fprintf (dump_file, "\nVisiting PHI node: ");
3672 print_generic_expr (dump_file, phi, dump_flags);
3675 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
3677 edge e = PHI_ARG_EDGE (phi, i);
3679 if (dump_file && (dump_flags & TDF_DETAILS))
3682 "\n Argument #%d (%d -> %d %sexecutable)\n",
3683 i, e->src->index, e->dest->index,
3684 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
3687 if (e->flags & EDGE_EXECUTABLE)
3689 tree arg = PHI_ARG_DEF (phi, i);
3690 value_range_t vr_arg;
3692 if (TREE_CODE (arg) == SSA_NAME)
3693 vr_arg = *(get_value_range (arg));
3696 vr_arg.type = VR_RANGE;
3699 vr_arg.equiv = NULL;
3702 if (dump_file && (dump_flags & TDF_DETAILS))
3704 fprintf (dump_file, "\t");
3705 print_generic_expr (dump_file, arg, dump_flags);
3706 fprintf (dump_file, "\n\tValue: ");
3707 dump_value_range (dump_file, &vr_arg);
3708 fprintf (dump_file, "\n");
3711 vrp_meet (&vr_result, &vr_arg);
3713 if (vr_result.type == VR_VARYING)
3718 if (vr_result.type == VR_VARYING)
3721 /* To prevent infinite iterations in the algorithm, derive ranges
3722 when the new value is slightly bigger or smaller than the
3724 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE)
3726 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
3728 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
3729 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
3731 /* If the new minimum is smaller or larger than the previous
3732 one, go all the way to -INF. In the first case, to avoid
3733 iterating millions of times to reach -INF, and in the
3734 other case to avoid infinite bouncing between different
3736 if (cmp_min > 0 || cmp_min < 0)
3737 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
3739 /* Similarly, if the new maximum is smaller or larger than
3740 the previous one, go all the way to +INF. */
3741 if (cmp_max < 0 || cmp_max > 0)
3742 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
3744 /* If we ended up with a (-INF, +INF) range, set it to
3746 if (vr_result.min == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))
3747 && vr_result.max == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)))
3752 /* If the new range is different than the previous value, keep
3754 if (update_value_range (lhs, &vr_result))
3755 return SSA_PROP_INTERESTING;
3757 /* Nothing changed, don't add outgoing edges. */
3758 return SSA_PROP_NOT_INTERESTING;
3760 /* No match found. Set the LHS to VARYING. */
3762 set_value_range_to_varying (lhs_vr);
3763 return SSA_PROP_VARYING;
3766 /* Simplify a division or modulo operator to a right shift or
3767 bitwise and if the first operand is unsigned or is greater
3768 than zero and the second operand is an exact power of two. */
3771 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
3774 tree op = TREE_OPERAND (rhs, 0);
3775 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
3777 if (TYPE_UNSIGNED (TREE_TYPE (op)))
3779 val = integer_one_node;
3783 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node);
3786 if (val && integer_onep (val))
3789 tree op0 = TREE_OPERAND (rhs, 0);
3790 tree op1 = TREE_OPERAND (rhs, 1);
3792 if (rhs_code == TRUNC_DIV_EXPR)
3794 t = build_int_cst (NULL_TREE, tree_log2 (op1));
3795 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
3799 t = build_int_cst (TREE_TYPE (op1), 1);
3800 t = int_const_binop (MINUS_EXPR, op1, t, 0);
3801 t = fold_convert (TREE_TYPE (op0), t);
3802 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
3805 TREE_OPERAND (stmt, 1) = t;
3810 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
3811 ABS_EXPR. If the operand is <= 0, then simplify the
3812 ABS_EXPR into a NEGATE_EXPR. */
3815 simplify_abs_using_ranges (tree stmt, tree rhs)
3818 tree op = TREE_OPERAND (rhs, 0);
3819 tree type = TREE_TYPE (op);
3820 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
3822 if (TYPE_UNSIGNED (type))
3824 val = integer_zero_node;
3828 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node);
3831 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node);
3835 if (integer_zerop (val))
3836 val = integer_one_node;
3837 else if (integer_onep (val))
3838 val = integer_zero_node;
3843 && (integer_onep (val) || integer_zerop (val)))
3847 if (integer_onep (val))
3848 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
3852 TREE_OPERAND (stmt, 1) = t;
3858 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
3859 a known value range VR.
3861 If there is one and only one value which will satisfy the
3862 conditional, then return that value. Else return NULL. */
3865 test_for_singularity (enum tree_code cond_code, tree op0,
3866 tree op1, value_range_t *vr)
3871 /* Extract minimum/maximum values which satisfy the
3872 the conditional as it was written. */
3873 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
3875 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
3878 if (cond_code == LT_EXPR)
3880 tree one = build_int_cst (TREE_TYPE (op0), 1);
3881 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
3884 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
3886 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
3889 if (cond_code == GT_EXPR)
3891 tree one = build_int_cst (TREE_TYPE (op0), 1);
3892 max = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), max, one);
3896 /* Now refine the minimum and maximum values using any
3897 value range information we have for op0. */
3900 if (compare_values (vr->min, min) == -1)
3904 if (compare_values (vr->max, max) == 1)
3909 /* If the new min/max values have converged to a
3910 single value, then there is only one value which
3911 can satisfy the condition, return that value. */
3912 if (min == max && is_gimple_min_invariant (min))
3918 /* Simplify a conditional using a relational operator to an equality
3919 test if the range information indicates only one value can satisfy
3920 the original conditional. */
3923 simplify_cond_using_ranges (tree stmt)
3925 tree cond = COND_EXPR_COND (stmt);
3926 tree op0 = TREE_OPERAND (cond, 0);
3927 tree op1 = TREE_OPERAND (cond, 1);
3928 enum tree_code cond_code = TREE_CODE (cond);
3930 if (cond_code != NE_EXPR
3931 && cond_code != EQ_EXPR
3932 && TREE_CODE (op0) == SSA_NAME
3933 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
3934 && is_gimple_min_invariant (op1))
3936 value_range_t *vr = get_value_range (op0);
3938 /* If we have range information for OP0, then we might be
3939 able to simplify this conditional. */
3940 if (vr->type == VR_RANGE)
3942 tree new = test_for_singularity (cond_code, op0, op1, vr);
3948 fprintf (dump_file, "Simplified relational ");
3949 print_generic_expr (dump_file, cond, 0);
3950 fprintf (dump_file, " into ");
3953 COND_EXPR_COND (stmt)
3954 = build (EQ_EXPR, boolean_type_node, op0, new);
3959 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
3960 fprintf (dump_file, "\n");
3966 /* Try again after inverting the condition. We only deal
3967 with integral types here, so no need to worry about
3968 issues with inverting FP comparisons. */
3969 cond_code = invert_tree_comparison (cond_code, false);
3970 new = test_for_singularity (cond_code, op0, op1, vr);
3976 fprintf (dump_file, "Simplified relational ");
3977 print_generic_expr (dump_file, cond, 0);
3978 fprintf (dump_file, " into ");
3981 COND_EXPR_COND (stmt)
3982 = build (NE_EXPR, boolean_type_node, op0, new);
3987 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
3988 fprintf (dump_file, "\n");
3997 /* Simplify STMT using ranges if possible. */
4000 simplify_stmt_using_ranges (tree stmt)
4002 if (TREE_CODE (stmt) == MODIFY_EXPR)
4004 tree rhs = TREE_OPERAND (stmt, 1);
4005 enum tree_code rhs_code = TREE_CODE (rhs);
4007 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
4008 and BIT_AND_EXPR respectively if the first operand is greater
4009 than zero and the second operand is an exact power of two. */
4010 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
4011 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
4012 && integer_pow2p (TREE_OPERAND (rhs, 1)))
4013 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
4015 /* Transform ABS (X) into X or -X as appropriate. */
4016 if (rhs_code == ABS_EXPR
4017 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
4018 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
4019 simplify_abs_using_ranges (stmt, rhs);
4021 else if (TREE_CODE (stmt) == COND_EXPR
4022 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
4024 simplify_cond_using_ranges (stmt);
4030 /* Traverse all the blocks folding conditionals with known ranges. */
4036 prop_value_t *single_val_range;
4037 bool do_value_subst_p;
4041 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
4042 dump_all_value_ranges (dump_file);
4043 fprintf (dump_file, "\n");
4046 /* We may have ended with ranges that have exactly one value. Those
4047 values can be substituted as any other copy/const propagated
4048 value using substitute_and_fold. */
4049 single_val_range = xmalloc (num_ssa_names * sizeof (*single_val_range));
4050 memset (single_val_range, 0, num_ssa_names * sizeof (*single_val_range));
4052 do_value_subst_p = false;
4053 for (i = 0; i < num_ssa_names; i++)
4055 && vr_value[i]->type == VR_RANGE
4056 && vr_value[i]->min == vr_value[i]->max)
4058 single_val_range[i].value = vr_value[i]->min;
4059 do_value_subst_p = true;
4062 if (!do_value_subst_p)
4064 /* We found no single-valued ranges, don't waste time trying to
4065 do single value substitution in substitute_and_fold. */
4066 free (single_val_range);
4067 single_val_range = NULL;
4070 substitute_and_fold (single_val_range, true);
4072 /* Free allocated memory. */
4073 for (i = 0; i < num_ssa_names; i++)
4076 BITMAP_FREE (vr_value[i]->equiv);
4080 free (single_val_range);
4085 /* Main entry point to VRP (Value Range Propagation). This pass is
4086 loosely based on J. R. C. Patterson, ``Accurate Static Branch
4087 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
4088 Programming Language Design and Implementation, pp. 67-78, 1995.
4089 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
4091 This is essentially an SSA-CCP pass modified to deal with ranges
4092 instead of constants.
4094 While propagating ranges, we may find that two or more SSA name
4095 have equivalent, though distinct ranges. For instance,
4098 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
4100 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
4104 In the code above, pointer p_5 has range [q_2, q_2], but from the
4105 code we can also determine that p_5 cannot be NULL and, if q_2 had
4106 a non-varying range, p_5's range should also be compatible with it.
4108 These equivalences are created by two expressions: ASSERT_EXPR and
4109 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
4110 result of another assertion, then we can use the fact that p_5 and
4111 p_4 are equivalent when evaluating p_5's range.
4113 Together with value ranges, we also propagate these equivalences
4114 between names so that we can take advantage of information from
4115 multiple ranges when doing final replacement. Note that this
4116 equivalency relation is transitive but not symmetric.
4118 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
4119 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
4120 in contexts where that assertion does not hold (e.g., in line 6).
4122 TODO, the main difference between this pass and Patterson's is that
4123 we do not propagate edge probabilities. We only compute whether
4124 edges can be taken or not. That is, instead of having a spectrum
4125 of jump probabilities between 0 and 1, we only deal with 0, 1 and
4126 DON'T KNOW. In the future, it may be worthwhile to propagate
4127 probabilities to aid branch prediction. */
4132 insert_range_assertions ();
4134 cfg_loops = loop_optimizer_init (NULL);
4136 scev_initialize (cfg_loops);
4139 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
4145 loop_optimizer_finalize (cfg_loops, NULL);
4146 current_loops = NULL;
4149 remove_range_assertions ();
4155 return flag_tree_vrp != 0;
4158 struct tree_opt_pass pass_vrp =
4161 gate_vrp, /* gate */
4162 execute_vrp, /* execute */
4165 0, /* static_pass_number */
4166 TV_TREE_VRP, /* tv_id */
4167 PROP_ssa | PROP_alias, /* properties_required */
4168 0, /* properties_provided */
4169 0, /* properties_destroyed */
4170 0, /* todo_flags_start */
4175 | TODO_update_ssa, /* todo_flags_finish */