1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005, 2006 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 /* Local functions. */
45 static int compare_values (tree val1, tree val2);
47 /* Location information for ASSERT_EXPRs. Each instance of this
48 structure describes an ASSERT_EXPR for an SSA name. Since a single
49 SSA name may have more than one assertion associated with it, these
50 locations are kept in a linked list attached to the corresponding
54 /* Basic block where the assertion would be inserted. */
57 /* Some assertions need to be inserted on an edge (e.g., assertions
58 generated by COND_EXPRs). In those cases, BB will be NULL. */
61 /* Pointer to the statement that generated this assertion. */
62 block_stmt_iterator si;
64 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
65 enum tree_code comp_code;
67 /* Value being compared against. */
70 /* Next node in the linked list. */
71 struct assert_locus_d *next;
74 typedef struct assert_locus_d *assert_locus_t;
76 /* If bit I is present, it means that SSA name N_i has a list of
77 assertions that should be inserted in the IL. */
78 static bitmap need_assert_for;
80 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
81 holds a list of ASSERT_LOCUS_T nodes that describe where
82 ASSERT_EXPRs for SSA name N_I should be inserted. */
83 static assert_locus_t *asserts_for;
85 /* Set of blocks visited in find_assert_locations. Used to avoid
86 visiting the same block more than once. */
87 static sbitmap blocks_visited;
89 /* Value range array. After propagation, VR_VALUE[I] holds the range
90 of values that SSA name N_I may take. */
91 static value_range_t **vr_value;
94 /* Return true if ARG is marked with the nonnull attribute in the
95 current function signature. */
98 nonnull_arg_p (tree arg)
100 tree t, attrs, fntype;
101 unsigned HOST_WIDE_INT arg_num;
103 gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
105 fntype = TREE_TYPE (current_function_decl);
106 attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype));
108 /* If "nonnull" wasn't specified, we know nothing about the argument. */
109 if (attrs == NULL_TREE)
112 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
113 if (TREE_VALUE (attrs) == NULL_TREE)
116 /* Get the position number for ARG in the function signature. */
117 for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl);
119 t = TREE_CHAIN (t), arg_num++)
125 gcc_assert (t == arg);
127 /* Now see if ARG_NUM is mentioned in the nonnull list. */
128 for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
130 if (compare_tree_int (TREE_VALUE (t), arg_num) == 0)
138 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
141 set_value_range (value_range_t *vr, enum value_range_type t, tree min,
142 tree max, bitmap equiv)
144 #if defined ENABLE_CHECKING
145 /* Check the validity of the range. */
146 if (t == VR_RANGE || t == VR_ANTI_RANGE)
150 gcc_assert (min && max);
152 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
153 gcc_assert (min != TYPE_MIN_VALUE (TREE_TYPE (min))
154 || max != TYPE_MAX_VALUE (TREE_TYPE (max)));
156 cmp = compare_values (min, max);
157 gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
160 if (t == VR_UNDEFINED || t == VR_VARYING)
161 gcc_assert (min == NULL_TREE && max == NULL_TREE);
163 if (t == VR_UNDEFINED || t == VR_VARYING)
164 gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
171 /* Since updating the equivalence set involves deep copying the
172 bitmaps, only do it if absolutely necessary. */
173 if (vr->equiv == NULL)
174 vr->equiv = BITMAP_ALLOC (NULL);
176 if (equiv != vr->equiv)
178 if (equiv && !bitmap_empty_p (equiv))
179 bitmap_copy (vr->equiv, equiv);
181 bitmap_clear (vr->equiv);
186 /* Copy value range FROM into value range TO. */
189 copy_value_range (value_range_t *to, value_range_t *from)
191 set_value_range (to, from->type, from->min, from->max, from->equiv);
194 /* Set value range VR to a non-negative range of type TYPE. */
197 set_value_range_to_nonnegative (value_range_t *vr, tree type)
199 tree zero = build_int_cst (type, 0);
200 set_value_range (vr, VR_RANGE, zero, TYPE_MAX_VALUE (type), vr->equiv);
203 /* Set value range VR to a non-NULL range of type TYPE. */
206 set_value_range_to_nonnull (value_range_t *vr, tree type)
208 tree zero = build_int_cst (type, 0);
209 set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
213 /* Set value range VR to a NULL range of type TYPE. */
216 set_value_range_to_null (value_range_t *vr, tree type)
218 tree zero = build_int_cst (type, 0);
219 set_value_range (vr, VR_RANGE, zero, zero, vr->equiv);
223 /* Set value range VR to VR_VARYING. */
226 set_value_range_to_varying (value_range_t *vr)
228 vr->type = VR_VARYING;
229 vr->min = vr->max = NULL_TREE;
231 bitmap_clear (vr->equiv);
235 /* Set value range VR to VR_UNDEFINED. */
238 set_value_range_to_undefined (value_range_t *vr)
240 vr->type = VR_UNDEFINED;
241 vr->min = vr->max = NULL_TREE;
243 bitmap_clear (vr->equiv);
247 /* Return value range information for VAR.
249 If we have no values ranges recorded (ie, VRP is not running), then
250 return NULL. Otherwise create an empty range if none existed for VAR. */
252 static value_range_t *
253 get_value_range (tree var)
257 unsigned ver = SSA_NAME_VERSION (var);
259 /* If we have no recorded ranges, then return NULL. */
267 /* Create a default value range. */
268 vr_value[ver] = vr = XNEW (value_range_t);
269 memset (vr, 0, sizeof (*vr));
271 /* Allocate an equivalence set. */
272 vr->equiv = BITMAP_ALLOC (NULL);
274 /* If VAR is a default definition, the variable can take any value
276 sym = SSA_NAME_VAR (var);
277 if (var == default_def (sym))
279 /* Try to use the "nonnull" attribute to create ~[0, 0]
280 anti-ranges for pointers. Note that this is only valid with
281 default definitions of PARM_DECLs. */
282 if (TREE_CODE (sym) == PARM_DECL
283 && POINTER_TYPE_P (TREE_TYPE (sym))
284 && nonnull_arg_p (sym))
285 set_value_range_to_nonnull (vr, TREE_TYPE (sym));
287 set_value_range_to_varying (vr);
294 /* Update the value range and equivalence set for variable VAR to
295 NEW_VR. Return true if NEW_VR is different from VAR's previous
298 NOTE: This function assumes that NEW_VR is a temporary value range
299 object created for the sole purpose of updating VAR's range. The
300 storage used by the equivalence set from NEW_VR will be freed by
301 this function. Do not call update_value_range when NEW_VR
302 is the range object associated with another SSA name. */
305 update_value_range (tree var, value_range_t *new_vr)
307 value_range_t *old_vr;
310 /* Update the value range, if necessary. */
311 old_vr = get_value_range (var);
312 is_new = old_vr->type != new_vr->type
313 || old_vr->min != new_vr->min
314 || old_vr->max != new_vr->max
315 || (old_vr->equiv == NULL && new_vr->equiv)
316 || (old_vr->equiv && new_vr->equiv == NULL)
317 || (!bitmap_equal_p (old_vr->equiv, new_vr->equiv));
320 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
323 BITMAP_FREE (new_vr->equiv);
324 new_vr->equiv = NULL;
330 /* Add VAR and VAR's equivalence set to EQUIV. */
333 add_equivalence (bitmap equiv, tree var)
335 unsigned ver = SSA_NAME_VERSION (var);
336 value_range_t *vr = vr_value[ver];
338 bitmap_set_bit (equiv, ver);
340 bitmap_ior_into (equiv, vr->equiv);
344 /* Return true if VR is ~[0, 0]. */
347 range_is_nonnull (value_range_t *vr)
349 return vr->type == VR_ANTI_RANGE
350 && integer_zerop (vr->min)
351 && integer_zerop (vr->max);
355 /* Return true if VR is [0, 0]. */
358 range_is_null (value_range_t *vr)
360 return vr->type == VR_RANGE
361 && integer_zerop (vr->min)
362 && integer_zerop (vr->max);
366 /* Return true if value range VR involves at least one symbol. */
369 symbolic_range_p (value_range_t *vr)
371 return (!is_gimple_min_invariant (vr->min)
372 || !is_gimple_min_invariant (vr->max));
375 /* Like tree_expr_nonnegative_p, but this function uses value ranges
379 vrp_expr_computes_nonnegative (tree expr)
381 return tree_expr_nonnegative_p (expr);
384 /* Like tree_expr_nonzero_p, but this function uses value ranges
388 vrp_expr_computes_nonzero (tree expr)
390 if (tree_expr_nonzero_p (expr))
393 /* If we have an expression of the form &X->a, then the expression
394 is nonnull if X is nonnull. */
395 if (TREE_CODE (expr) == ADDR_EXPR)
397 tree base = get_base_address (TREE_OPERAND (expr, 0));
399 if (base != NULL_TREE
400 && TREE_CODE (base) == INDIRECT_REF
401 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
403 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
404 if (range_is_nonnull (vr))
413 /* Compare two values VAL1 and VAL2. Return
415 -2 if VAL1 and VAL2 cannot be compared at compile-time,
418 +1 if VAL1 > VAL2, and
421 This is similar to tree_int_cst_compare but supports pointer values
422 and values that cannot be compared at compile time. */
425 compare_values (tree val1, tree val2)
430 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
432 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
433 == POINTER_TYPE_P (TREE_TYPE (val2)));
435 if ((TREE_CODE (val1) == SSA_NAME
436 || TREE_CODE (val1) == PLUS_EXPR
437 || TREE_CODE (val1) == MINUS_EXPR)
438 && (TREE_CODE (val2) == SSA_NAME
439 || TREE_CODE (val2) == PLUS_EXPR
440 || TREE_CODE (val2) == MINUS_EXPR))
443 enum tree_code code1, code2;
445 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
446 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
447 same name, return -2. */
448 if (TREE_CODE (val1) == SSA_NAME)
456 code1 = TREE_CODE (val1);
457 n1 = TREE_OPERAND (val1, 0);
458 c1 = TREE_OPERAND (val1, 1);
459 if (tree_int_cst_sgn (c1) == -1)
461 c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1);
464 code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
468 if (TREE_CODE (val2) == SSA_NAME)
476 code2 = TREE_CODE (val2);
477 n2 = TREE_OPERAND (val2, 0);
478 c2 = TREE_OPERAND (val2, 1);
479 if (tree_int_cst_sgn (c2) == -1)
481 c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2);
484 code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
488 /* Both values must use the same name. */
492 if (code1 == SSA_NAME
493 && code2 == SSA_NAME)
497 /* If overflow is defined we cannot simplify more. */
498 if (TYPE_UNSIGNED (TREE_TYPE (val1))
502 if (code1 == SSA_NAME)
504 if (code2 == PLUS_EXPR)
505 /* NAME < NAME + CST */
507 else if (code2 == MINUS_EXPR)
508 /* NAME > NAME - CST */
511 else if (code1 == PLUS_EXPR)
513 if (code2 == SSA_NAME)
514 /* NAME + CST > NAME */
516 else if (code2 == PLUS_EXPR)
517 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
518 return compare_values (c1, c2);
519 else if (code2 == MINUS_EXPR)
520 /* NAME + CST1 > NAME - CST2 */
523 else if (code1 == MINUS_EXPR)
525 if (code2 == SSA_NAME)
526 /* NAME - CST < NAME */
528 else if (code2 == PLUS_EXPR)
529 /* NAME - CST1 < NAME + CST2 */
531 else if (code2 == MINUS_EXPR)
532 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
533 C1 and C2 are swapped in the call to compare_values. */
534 return compare_values (c2, c1);
540 /* We cannot compare non-constants. */
541 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
544 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
546 /* We cannot compare overflowed values. */
547 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
550 return tree_int_cst_compare (val1, val2);
556 /* First see if VAL1 and VAL2 are not the same. */
557 if (val1 == val2 || operand_equal_p (val1, val2, 0))
560 /* If VAL1 is a lower address than VAL2, return -1. */
561 t = fold_binary (LT_EXPR, boolean_type_node, val1, val2);
562 if (t == boolean_true_node)
565 /* If VAL1 is a higher address than VAL2, return +1. */
566 t = fold_binary (GT_EXPR, boolean_type_node, val1, val2);
567 if (t == boolean_true_node)
570 /* If VAL1 is different than VAL2, return +2. */
571 t = fold_binary (NE_EXPR, boolean_type_node, val1, val2);
572 if (t == boolean_true_node)
580 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
581 0 if VAL is not inside VR,
582 -2 if we cannot tell either way.
584 FIXME, the current semantics of this functions are a bit quirky
585 when taken in the context of VRP. In here we do not care
586 about VR's type. If VR is the anti-range ~[3, 5] the call
587 value_inside_range (4, VR) will return 1.
589 This is counter-intuitive in a strict sense, but the callers
590 currently expect this. They are calling the function
591 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
592 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
595 This also applies to value_ranges_intersect_p and
596 range_includes_zero_p. The semantics of VR_RANGE and
597 VR_ANTI_RANGE should be encoded here, but that also means
598 adapting the users of these functions to the new semantics. */
601 value_inside_range (tree val, value_range_t *vr)
605 cmp1 = fold_binary_to_constant (GE_EXPR, boolean_type_node, val, vr->min);
609 cmp2 = fold_binary_to_constant (LE_EXPR, boolean_type_node, val, vr->max);
613 return cmp1 == boolean_true_node && cmp2 == boolean_true_node;
617 /* Return true if value ranges VR0 and VR1 have a non-empty
621 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
623 return (value_inside_range (vr1->min, vr0) == 1
624 || value_inside_range (vr1->max, vr0) == 1
625 || value_inside_range (vr0->min, vr1) == 1
626 || value_inside_range (vr0->max, vr1) == 1);
630 /* Return true if VR includes the value zero, false otherwise. FIXME,
631 currently this will return false for an anti-range like ~[-4, 3].
632 This will be wrong when the semantics of value_inside_range are
633 modified (currently the users of this function expect these
637 range_includes_zero_p (value_range_t *vr)
641 gcc_assert (vr->type != VR_UNDEFINED
642 && vr->type != VR_VARYING
643 && !symbolic_range_p (vr));
645 zero = build_int_cst (TREE_TYPE (vr->min), 0);
646 return (value_inside_range (zero, vr) == 1);
649 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
650 false otherwise or if no value range information is available. */
653 ssa_name_nonnegative_p (tree t)
655 value_range_t *vr = get_value_range (t);
660 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
661 which would return a useful value should be encoded as a VR_RANGE. */
662 if (vr->type == VR_RANGE)
664 int result = compare_values (vr->min, integer_zero_node);
666 return (result == 0 || result == 1);
671 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
672 false otherwise or if no value range information is available. */
675 ssa_name_nonzero_p (tree t)
677 value_range_t *vr = get_value_range (t);
682 /* A VR_RANGE which does not include zero is a nonzero value. */
683 if (vr->type == VR_RANGE && !symbolic_range_p (vr))
684 return ! range_includes_zero_p (vr);
686 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
687 if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr))
688 return range_includes_zero_p (vr);
694 /* When extracting ranges from X_i = ASSERT_EXPR <Y_j, pred>, we will
695 initially consider X_i and Y_j equivalent, so the equivalence set
696 of Y_j is added to the equivalence set of X_i. However, it is
697 possible to have a chain of ASSERT_EXPRs whose predicates are
698 actually incompatible. This is usually the result of nesting of
699 contradictory if-then-else statements. For instance, in PR 24670:
701 count_4 has range [-INF, 63]
705 count_19 = ASSERT_EXPR <count_4, count_4 != 0>
708 count_18 = ASSERT_EXPR <count_19, count_19 > 63>
714 Notice that 'if (count_19 > 63)' is trivially false and will be
715 folded out at the end. However, during propagation, the flowgraph
716 is not cleaned up and so, VRP will evaluate predicates more
717 predicates than necessary, so it must support these
718 inconsistencies. The problem here is that because of the chaining
719 of ASSERT_EXPRs, the equivalency set for count_18 includes count_4.
720 Since count_4 has an incompatible range, we ICE when evaluating the
721 ranges in the equivalency set. So, we need to remove count_4 from
725 fix_equivalence_set (value_range_t *vr_p)
729 bitmap e = vr_p->equiv;
730 bitmap to_remove = BITMAP_ALLOC (NULL);
732 /* Only detect inconsistencies on numeric ranges. */
733 if (vr_p->type == VR_VARYING
734 || vr_p->type == VR_UNDEFINED
735 || symbolic_range_p (vr_p))
738 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
740 value_range_t *equiv_vr = vr_value[i];
742 if (equiv_vr->type == VR_VARYING
743 || equiv_vr->type == VR_UNDEFINED
744 || symbolic_range_p (equiv_vr))
747 if (equiv_vr->type == VR_RANGE
748 && vr_p->type == VR_RANGE
749 && !value_ranges_intersect_p (vr_p, equiv_vr))
750 bitmap_set_bit (to_remove, i);
751 else if ((equiv_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
752 || (equiv_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
754 /* A range and an anti-range have an empty intersection if
755 their end points are the same. FIXME,
756 value_ranges_intersect_p should handle this
758 if (compare_values (equiv_vr->min, vr_p->min) == 0
759 && compare_values (equiv_vr->max, vr_p->max) == 0)
760 bitmap_set_bit (to_remove, i);
764 bitmap_and_compl_into (vr_p->equiv, to_remove);
765 BITMAP_FREE (to_remove);
769 /* Extract value range information from an ASSERT_EXPR EXPR and store
773 extract_range_from_assert (value_range_t *vr_p, tree expr)
775 tree var, cond, limit, min, max, type;
776 value_range_t *var_vr, *limit_vr;
777 enum tree_code cond_code;
779 var = ASSERT_EXPR_VAR (expr);
780 cond = ASSERT_EXPR_COND (expr);
782 gcc_assert (COMPARISON_CLASS_P (cond));
784 /* Find VAR in the ASSERT_EXPR conditional. */
785 if (var == TREE_OPERAND (cond, 0))
787 /* If the predicate is of the form VAR COMP LIMIT, then we just
788 take LIMIT from the RHS and use the same comparison code. */
789 limit = TREE_OPERAND (cond, 1);
790 cond_code = TREE_CODE (cond);
794 /* If the predicate is of the form LIMIT COMP VAR, then we need
795 to flip around the comparison code to create the proper range
797 limit = TREE_OPERAND (cond, 0);
798 cond_code = swap_tree_comparison (TREE_CODE (cond));
801 type = TREE_TYPE (limit);
802 gcc_assert (limit != var);
804 /* For pointer arithmetic, we only keep track of pointer equality
806 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
808 set_value_range_to_varying (vr_p);
812 /* If LIMIT is another SSA name and LIMIT has a range of its own,
813 try to use LIMIT's range to avoid creating symbolic ranges
815 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
817 /* LIMIT's range is only interesting if it has any useful information. */
819 && (limit_vr->type == VR_UNDEFINED
820 || limit_vr->type == VR_VARYING
821 || symbolic_range_p (limit_vr)))
824 /* Initially, the new range has the same set of equivalences of
825 VAR's range. This will be revised before returning the final
826 value. Since assertions may be chained via mutually exclusive
827 predicates, we will need to trim the set of equivalences before
829 gcc_assert (vr_p->equiv == NULL);
830 vr_p->equiv = BITMAP_ALLOC (NULL);
831 add_equivalence (vr_p->equiv, var);
833 /* Extract a new range based on the asserted comparison for VAR and
834 LIMIT's value range. Notice that if LIMIT has an anti-range, we
835 will only use it for equality comparisons (EQ_EXPR). For any
836 other kind of assertion, we cannot derive a range from LIMIT's
837 anti-range that can be used to describe the new range. For
838 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
839 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
840 no single range for x_2 that could describe LE_EXPR, so we might
841 as well build the range [b_4, +INF] for it. */
842 if (cond_code == EQ_EXPR)
844 enum value_range_type range_type;
848 range_type = limit_vr->type;
854 range_type = VR_RANGE;
859 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
861 /* When asserting the equality VAR == LIMIT and LIMIT is another
862 SSA name, the new range will also inherit the equivalence set
864 if (TREE_CODE (limit) == SSA_NAME)
865 add_equivalence (vr_p->equiv, limit);
867 else if (cond_code == NE_EXPR)
869 /* As described above, when LIMIT's range is an anti-range and
870 this assertion is an inequality (NE_EXPR), then we cannot
871 derive anything from the anti-range. For instance, if
872 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
873 not imply that VAR's range is [0, 0]. So, in the case of
874 anti-ranges, we just assert the inequality using LIMIT and
877 If LIMIT_VR is a range, we can only use it to build a new
878 anti-range if LIMIT_VR is a single-valued range. For
879 instance, if LIMIT_VR is [0, 1], the predicate
880 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
881 Rather, it means that for value 0 VAR should be ~[0, 0]
882 and for value 1, VAR should be ~[1, 1]. We cannot
883 represent these ranges.
885 The only situation in which we can build a valid
886 anti-range is when LIMIT_VR is a single-valued range
887 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
888 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
890 && limit_vr->type == VR_RANGE
891 && compare_values (limit_vr->min, limit_vr->max) == 0)
898 /* In any other case, we cannot use LIMIT's range to build a
903 /* If MIN and MAX cover the whole range for their type, then
904 just use the original LIMIT. */
905 if (INTEGRAL_TYPE_P (type)
906 && min == TYPE_MIN_VALUE (type)
907 && max == TYPE_MAX_VALUE (type))
910 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
912 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
914 min = TYPE_MIN_VALUE (type);
916 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
920 /* If LIMIT_VR is of the form [N1, N2], we need to build the
921 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
926 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
927 if (cond_code == LT_EXPR)
929 tree one = build_int_cst (type, 1);
930 max = fold_build2 (MINUS_EXPR, type, max, one);
933 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
935 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
937 max = TYPE_MAX_VALUE (type);
939 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
943 /* If LIMIT_VR is of the form [N1, N2], we need to build the
944 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
949 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
950 if (cond_code == GT_EXPR)
952 tree one = build_int_cst (type, 1);
953 min = fold_build2 (PLUS_EXPR, type, min, one);
956 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
961 /* If VAR already had a known range, it may happen that the new
962 range we have computed and VAR's range are not compatible. For
966 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
968 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
970 While the above comes from a faulty program, it will cause an ICE
971 later because p_8 and p_6 will have incompatible ranges and at
972 the same time will be considered equivalent. A similar situation
976 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
978 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
980 Again i_6 and i_7 will have incompatible ranges. It would be
981 pointless to try and do anything with i_7's range because
982 anything dominated by 'if (i_5 < 5)' will be optimized away.
983 Note, due to the wa in which simulation proceeds, the statement
984 i_7 = ASSERT_EXPR <...> we would never be visited because the
985 conditional 'if (i_5 < 5)' always evaluates to false. However,
986 this extra check does not hurt and may protect against future
987 changes to VRP that may get into a situation similar to the
988 NULL pointer dereference example.
990 Note that these compatibility tests are only needed when dealing
991 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
992 are both anti-ranges, they will always be compatible, because two
993 anti-ranges will always have a non-empty intersection. */
995 var_vr = get_value_range (var);
997 /* We may need to make adjustments when VR_P and VAR_VR are numeric
998 ranges or anti-ranges. */
999 if (vr_p->type == VR_VARYING
1000 || vr_p->type == VR_UNDEFINED
1001 || var_vr->type == VR_VARYING
1002 || var_vr->type == VR_UNDEFINED
1003 || symbolic_range_p (vr_p)
1004 || symbolic_range_p (var_vr))
1007 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
1009 /* If the two ranges have a non-empty intersection, we can
1010 refine the resulting range. Since the assert expression
1011 creates an equivalency and at the same time it asserts a
1012 predicate, we can take the intersection of the two ranges to
1013 get better precision. */
1014 if (value_ranges_intersect_p (var_vr, vr_p))
1016 /* Use the larger of the two minimums. */
1017 if (compare_values (vr_p->min, var_vr->min) == -1)
1022 /* Use the smaller of the two maximums. */
1023 if (compare_values (vr_p->max, var_vr->max) == 1)
1028 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
1032 /* The two ranges do not intersect, set the new range to
1033 VARYING, because we will not be able to do anything
1034 meaningful with it. */
1035 set_value_range_to_varying (vr_p);
1038 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
1039 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
1041 /* A range and an anti-range will cancel each other only if
1042 their ends are the same. For instance, in the example above,
1043 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1044 so VR_P should be set to VR_VARYING. */
1045 if (compare_values (var_vr->min, vr_p->min) == 0
1046 && compare_values (var_vr->max, vr_p->max) == 0)
1047 set_value_range_to_varying (vr_p);
1050 tree min, max, anti_min, anti_max, real_min, real_max;
1052 /* We want to compute the logical AND of the two ranges;
1053 there are three cases to consider.
1056 1. The VR_ANTI_RANGE range is completely within the
1057 VR_RANGE and the endpoints of the ranges are
1058 different. In that case the resulting range
1059 should be whichever range is more precise.
1060 Typically that will be the VR_RANGE.
1062 2. The VR_ANTI_RANGE is completely disjoint from
1063 the VR_RANGE. In this case the resulting range
1064 should be the VR_RANGE.
1066 3. There is some overlap between the VR_ANTI_RANGE
1069 3a. If the high limit of the VR_ANTI_RANGE resides
1070 within the VR_RANGE, then the result is a new
1071 VR_RANGE starting at the high limit of the
1072 the VR_ANTI_RANGE + 1 and extending to the
1073 high limit of the original VR_RANGE.
1075 3b. If the low limit of the VR_ANTI_RANGE resides
1076 within the VR_RANGE, then the result is a new
1077 VR_RANGE starting at the low limit of the original
1078 VR_RANGE and extending to the low limit of the
1079 VR_ANTI_RANGE - 1. */
1080 if (vr_p->type == VR_ANTI_RANGE)
1082 anti_min = vr_p->min;
1083 anti_max = vr_p->max;
1084 real_min = var_vr->min;
1085 real_max = var_vr->max;
1089 anti_min = var_vr->min;
1090 anti_max = var_vr->max;
1091 real_min = vr_p->min;
1092 real_max = vr_p->max;
1096 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1097 not including any endpoints. */
1098 if (compare_values (anti_max, real_max) == -1
1099 && compare_values (anti_min, real_min) == 1)
1101 set_value_range (vr_p, VR_RANGE, real_min,
1102 real_max, vr_p->equiv);
1104 /* Case 2, VR_ANTI_RANGE completely disjoint from
1106 else if (compare_values (anti_min, real_max) == 1
1107 || compare_values (anti_max, real_min) == -1)
1109 set_value_range (vr_p, VR_RANGE, real_min,
1110 real_max, vr_p->equiv);
1112 /* Case 3a, the anti-range extends into the low
1113 part of the real range. Thus creating a new
1114 low for the real range. */
1115 else if ((compare_values (anti_max, real_min) == 1
1116 || compare_values (anti_max, real_min) == 0)
1117 && compare_values (anti_max, real_max) == -1)
1119 min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min),
1121 build_int_cst (TREE_TYPE (var_vr->min), 1));
1123 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1125 /* Case 3b, the anti-range extends into the high
1126 part of the real range. Thus creating a new
1127 higher for the real range. */
1128 else if (compare_values (anti_min, real_min) == 1
1129 && (compare_values (anti_min, real_max) == -1
1130 || compare_values (anti_min, real_max) == 0))
1132 max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min),
1134 build_int_cst (TREE_TYPE (var_vr->min), 1));
1136 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1141 /* Remove names from the equivalence set that have ranges
1142 incompatible with VR_P. */
1144 fix_equivalence_set (vr_p);
1148 /* Extract range information from SSA name VAR and store it in VR. If
1149 VAR has an interesting range, use it. Otherwise, create the
1150 range [VAR, VAR] and return it. This is useful in situations where
1151 we may have conditionals testing values of VARYING names. For
1158 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1162 extract_range_from_ssa_name (value_range_t *vr, tree var)
1164 value_range_t *var_vr = get_value_range (var);
1166 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
1167 copy_value_range (vr, var_vr);
1169 set_value_range (vr, VR_RANGE, var, var, NULL);
1171 add_equivalence (vr->equiv, var);
1175 /* Wrapper around int_const_binop. If the operation overflows and we
1176 are not using wrapping arithmetic, then adjust the result to be
1177 -INF or +INF depending on CODE, VAL1 and VAL2. */
1180 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
1185 return int_const_binop (code, val1, val2, 0);
1187 /* If we are not using wrapping arithmetic, operate symbolically
1188 on -INF and +INF. */
1189 res = int_const_binop (code, val1, val2, 0);
1191 if (TYPE_UNSIGNED (TREE_TYPE (val1)))
1193 int checkz = compare_values (res, val1);
1194 bool overflow = false;
1196 /* Ensure that res = val1 [+*] val2 >= val1
1197 or that res = val1 - val2 <= val1. */
1198 if ((code == PLUS_EXPR
1199 && !(checkz == 1 || checkz == 0))
1200 || (code == MINUS_EXPR
1201 && !(checkz == 0 || checkz == -1)))
1205 /* Checking for multiplication overflow is done by dividing the
1206 output of the multiplication by the first input of the
1207 multiplication. If the result of that division operation is
1208 not equal to the second input of the multiplication, then the
1209 multiplication overflowed. */
1210 else if (code == MULT_EXPR && !integer_zerop (val1))
1212 tree tmp = int_const_binop (TRUNC_DIV_EXPR,
1213 TYPE_MAX_VALUE (TREE_TYPE (val1)),
1215 int check = compare_values (tmp, val2);
1223 res = copy_node (res);
1224 TREE_OVERFLOW (res) = 1;
1228 else if (TREE_OVERFLOW (res)
1229 && !TREE_OVERFLOW (val1)
1230 && !TREE_OVERFLOW (val2))
1232 /* If the operation overflowed but neither VAL1 nor VAL2 are
1233 overflown, return -INF or +INF depending on the operation
1234 and the combination of signs of the operands. */
1235 int sgn1 = tree_int_cst_sgn (val1);
1236 int sgn2 = tree_int_cst_sgn (val2);
1238 /* Notice that we only need to handle the restricted set of
1239 operations handled by extract_range_from_binary_expr.
1240 Among them, only multiplication, addition and subtraction
1241 can yield overflow without overflown operands because we
1242 are working with integral types only... except in the
1243 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1244 for division too. */
1246 /* For multiplication, the sign of the overflow is given
1247 by the comparison of the signs of the operands. */
1248 if ((code == MULT_EXPR && sgn1 == sgn2)
1249 /* For addition, the operands must be of the same sign
1250 to yield an overflow. Its sign is therefore that
1251 of one of the operands, for example the first. */
1252 || (code == PLUS_EXPR && sgn1 > 0)
1253 /* For subtraction, the operands must be of different
1254 signs to yield an overflow. Its sign is therefore
1255 that of the first operand or the opposite of that
1256 of the second operand. A first operand of 0 counts
1257 as positive here, for the corner case 0 - (-INF),
1258 which overflows, but must yield +INF. */
1259 || (code == MINUS_EXPR && sgn1 >= 0)
1260 /* For division, the only case is -INF / -1 = +INF. */
1261 || code == TRUNC_DIV_EXPR
1262 || code == FLOOR_DIV_EXPR
1263 || code == CEIL_DIV_EXPR
1264 || code == EXACT_DIV_EXPR
1265 || code == ROUND_DIV_EXPR)
1266 return TYPE_MAX_VALUE (TREE_TYPE (res));
1268 return TYPE_MIN_VALUE (TREE_TYPE (res));
1275 /* Extract range information from a binary expression EXPR based on
1276 the ranges of each of its operands and the expression code. */
1279 extract_range_from_binary_expr (value_range_t *vr, tree expr)
1281 enum tree_code code = TREE_CODE (expr);
1282 enum value_range_type type;
1283 tree op0, op1, min, max;
1285 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1286 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1288 /* Not all binary expressions can be applied to ranges in a
1289 meaningful way. Handle only arithmetic operations. */
1290 if (code != PLUS_EXPR
1291 && code != MINUS_EXPR
1292 && code != MULT_EXPR
1293 && code != TRUNC_DIV_EXPR
1294 && code != FLOOR_DIV_EXPR
1295 && code != CEIL_DIV_EXPR
1296 && code != EXACT_DIV_EXPR
1297 && code != ROUND_DIV_EXPR
1300 && code != BIT_AND_EXPR
1301 && code != TRUTH_ANDIF_EXPR
1302 && code != TRUTH_ORIF_EXPR
1303 && code != TRUTH_AND_EXPR
1304 && code != TRUTH_OR_EXPR)
1306 set_value_range_to_varying (vr);
1310 /* Get value ranges for each operand. For constant operands, create
1311 a new value range with the operand to simplify processing. */
1312 op0 = TREE_OPERAND (expr, 0);
1313 if (TREE_CODE (op0) == SSA_NAME)
1314 vr0 = *(get_value_range (op0));
1315 else if (is_gimple_min_invariant (op0))
1316 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1318 set_value_range_to_varying (&vr0);
1320 op1 = TREE_OPERAND (expr, 1);
1321 if (TREE_CODE (op1) == SSA_NAME)
1322 vr1 = *(get_value_range (op1));
1323 else if (is_gimple_min_invariant (op1))
1324 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1326 set_value_range_to_varying (&vr1);
1328 /* If either range is UNDEFINED, so is the result. */
1329 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1331 set_value_range_to_undefined (vr);
1335 /* The type of the resulting value range defaults to VR0.TYPE. */
1338 /* Refuse to operate on VARYING ranges, ranges of different kinds
1339 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1340 because we may be able to derive a useful range even if one of
1341 the operands is VR_VARYING or symbolic range. TODO, we may be
1342 able to derive anti-ranges in some cases. */
1343 if (code != BIT_AND_EXPR
1344 && code != TRUTH_AND_EXPR
1345 && code != TRUTH_OR_EXPR
1346 && (vr0.type == VR_VARYING
1347 || vr1.type == VR_VARYING
1348 || vr0.type != vr1.type
1349 || symbolic_range_p (&vr0)
1350 || symbolic_range_p (&vr1)))
1352 set_value_range_to_varying (vr);
1356 /* Now evaluate the expression to determine the new range. */
1357 if (POINTER_TYPE_P (TREE_TYPE (expr))
1358 || POINTER_TYPE_P (TREE_TYPE (op0))
1359 || POINTER_TYPE_P (TREE_TYPE (op1)))
1361 /* For pointer types, we are really only interested in asserting
1362 whether the expression evaluates to non-NULL. FIXME, we used
1363 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1364 ivopts is generating expressions with pointer multiplication
1366 if (code == PLUS_EXPR)
1368 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1369 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1370 else if (range_is_null (&vr0) && range_is_null (&vr1))
1371 set_value_range_to_null (vr, TREE_TYPE (expr));
1373 set_value_range_to_varying (vr);
1377 /* Subtracting from a pointer, may yield 0, so just drop the
1378 resulting range to varying. */
1379 set_value_range_to_varying (vr);
1385 /* For integer ranges, apply the operation to each end of the
1386 range and see what we end up with. */
1387 if (code == TRUTH_ANDIF_EXPR
1388 || code == TRUTH_ORIF_EXPR
1389 || code == TRUTH_AND_EXPR
1390 || code == TRUTH_OR_EXPR)
1392 /* If one of the operands is zero, we know that the whole
1393 expression evaluates zero. */
1394 if (code == TRUTH_AND_EXPR
1395 && ((vr0.type == VR_RANGE
1396 && integer_zerop (vr0.min)
1397 && integer_zerop (vr0.max))
1398 || (vr1.type == VR_RANGE
1399 && integer_zerop (vr1.min)
1400 && integer_zerop (vr1.max))))
1403 min = max = build_int_cst (TREE_TYPE (expr), 0);
1405 /* If one of the operands is one, we know that the whole
1406 expression evaluates one. */
1407 else if (code == TRUTH_OR_EXPR
1408 && ((vr0.type == VR_RANGE
1409 && integer_onep (vr0.min)
1410 && integer_onep (vr0.max))
1411 || (vr1.type == VR_RANGE
1412 && integer_onep (vr1.min)
1413 && integer_onep (vr1.max))))
1416 min = max = build_int_cst (TREE_TYPE (expr), 1);
1418 else if (vr0.type != VR_VARYING
1419 && vr1.type != VR_VARYING
1420 && vr0.type == vr1.type
1421 && !symbolic_range_p (&vr0)
1422 && !symbolic_range_p (&vr1))
1424 /* Boolean expressions cannot be folded with int_const_binop. */
1425 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1426 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1430 set_value_range_to_varying (vr);
1434 else if (code == PLUS_EXPR
1436 || code == MAX_EXPR)
1438 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1439 VR_VARYING. It would take more effort to compute a precise
1440 range for such a case. For example, if we have op0 == 1 and
1441 op1 == -1 with their ranges both being ~[0,0], we would have
1442 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1443 Note that we are guaranteed to have vr0.type == vr1.type at
1445 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1447 set_value_range_to_varying (vr);
1451 /* For operations that make the resulting range directly
1452 proportional to the original ranges, apply the operation to
1453 the same end of each range. */
1454 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1455 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1457 else if (code == MULT_EXPR
1458 || code == TRUNC_DIV_EXPR
1459 || code == FLOOR_DIV_EXPR
1460 || code == CEIL_DIV_EXPR
1461 || code == EXACT_DIV_EXPR
1462 || code == ROUND_DIV_EXPR)
1467 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1468 drop to VR_VARYING. It would take more effort to compute a
1469 precise range for such a case. For example, if we have
1470 op0 == 65536 and op1 == 65536 with their ranges both being
1471 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1472 we cannot claim that the product is in ~[0,0]. Note that we
1473 are guaranteed to have vr0.type == vr1.type at this
1475 if (code == MULT_EXPR
1476 && vr0.type == VR_ANTI_RANGE
1477 && (flag_wrapv || TYPE_UNSIGNED (TREE_TYPE (op0))))
1479 set_value_range_to_varying (vr);
1483 /* Multiplications and divisions are a bit tricky to handle,
1484 depending on the mix of signs we have in the two ranges, we
1485 need to operate on different values to get the minimum and
1486 maximum values for the new range. One approach is to figure
1487 out all the variations of range combinations and do the
1490 However, this involves several calls to compare_values and it
1491 is pretty convoluted. It's simpler to do the 4 operations
1492 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1493 MAX1) and then figure the smallest and largest values to form
1496 /* Divisions by zero result in a VARYING value. */
1497 if (code != MULT_EXPR
1498 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1500 set_value_range_to_varying (vr);
1504 /* Compute the 4 cross operations. */
1505 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1507 val[1] = (vr1.max != vr1.min)
1508 ? vrp_int_const_binop (code, vr0.min, vr1.max)
1511 val[2] = (vr0.max != vr0.min)
1512 ? vrp_int_const_binop (code, vr0.max, vr1.min)
1515 val[3] = (vr0.min != vr0.max && vr1.min != vr1.max)
1516 ? vrp_int_const_binop (code, vr0.max, vr1.max)
1519 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1523 for (i = 1; i < 4; i++)
1525 if (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
1526 || !is_gimple_min_invariant (max) || TREE_OVERFLOW (max))
1531 if (!is_gimple_min_invariant (val[i]) || TREE_OVERFLOW (val[i]))
1533 /* If we found an overflowed value, set MIN and MAX
1534 to it so that we set the resulting range to
1540 if (compare_values (val[i], min) == -1)
1543 if (compare_values (val[i], max) == 1)
1548 else if (code == MINUS_EXPR)
1550 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1551 VR_VARYING. It would take more effort to compute a precise
1552 range for such a case. For example, if we have op0 == 1 and
1553 op1 == 1 with their ranges both being ~[0,0], we would have
1554 op0 - op1 == 0, so we cannot claim that the difference is in
1555 ~[0,0]. Note that we are guaranteed to have
1556 vr0.type == vr1.type at this point. */
1557 if (vr0.type == VR_ANTI_RANGE)
1559 set_value_range_to_varying (vr);
1563 /* For MINUS_EXPR, apply the operation to the opposite ends of
1565 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1566 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1568 else if (code == BIT_AND_EXPR)
1570 if (vr0.type == VR_RANGE
1571 && vr0.min == vr0.max
1572 && tree_expr_nonnegative_p (vr0.max)
1573 && TREE_CODE (vr0.max) == INTEGER_CST)
1575 min = build_int_cst (TREE_TYPE (expr), 0);
1578 else if (vr1.type == VR_RANGE
1579 && vr1.min == vr1.max
1580 && tree_expr_nonnegative_p (vr1.max)
1581 && TREE_CODE (vr1.max) == INTEGER_CST)
1584 min = build_int_cst (TREE_TYPE (expr), 0);
1589 set_value_range_to_varying (vr);
1596 /* If either MIN or MAX overflowed, then set the resulting range to
1598 if (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
1599 || !is_gimple_min_invariant (max) || TREE_OVERFLOW (max))
1601 set_value_range_to_varying (vr);
1605 cmp = compare_values (min, max);
1606 if (cmp == -2 || cmp == 1)
1608 /* If the new range has its limits swapped around (MIN > MAX),
1609 then the operation caused one of them to wrap around, mark
1610 the new range VARYING. */
1611 set_value_range_to_varying (vr);
1614 set_value_range (vr, type, min, max, NULL);
1618 /* Extract range information from a unary expression EXPR based on
1619 the range of its operand and the expression code. */
1622 extract_range_from_unary_expr (value_range_t *vr, tree expr)
1624 enum tree_code code = TREE_CODE (expr);
1627 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1629 /* Refuse to operate on certain unary expressions for which we
1630 cannot easily determine a resulting range. */
1631 if (code == FIX_TRUNC_EXPR
1632 || code == FIX_CEIL_EXPR
1633 || code == FIX_FLOOR_EXPR
1634 || code == FIX_ROUND_EXPR
1635 || code == FLOAT_EXPR
1636 || code == BIT_NOT_EXPR
1637 || code == NON_LVALUE_EXPR
1638 || code == CONJ_EXPR)
1640 set_value_range_to_varying (vr);
1644 /* Get value ranges for the operand. For constant operands, create
1645 a new value range with the operand to simplify processing. */
1646 op0 = TREE_OPERAND (expr, 0);
1647 if (TREE_CODE (op0) == SSA_NAME)
1648 vr0 = *(get_value_range (op0));
1649 else if (is_gimple_min_invariant (op0))
1650 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1652 set_value_range_to_varying (&vr0);
1654 /* If VR0 is UNDEFINED, so is the result. */
1655 if (vr0.type == VR_UNDEFINED)
1657 set_value_range_to_undefined (vr);
1661 /* Refuse to operate on symbolic ranges, or if neither operand is
1662 a pointer or integral type. */
1663 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0))
1664 && !POINTER_TYPE_P (TREE_TYPE (op0)))
1665 || (vr0.type != VR_VARYING
1666 && symbolic_range_p (&vr0)))
1668 set_value_range_to_varying (vr);
1672 /* If the expression involves pointers, we are only interested in
1673 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1674 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
1676 if (range_is_nonnull (&vr0) || tree_expr_nonzero_p (expr))
1677 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1678 else if (range_is_null (&vr0))
1679 set_value_range_to_null (vr, TREE_TYPE (expr));
1681 set_value_range_to_varying (vr);
1686 /* Handle unary expressions on integer ranges. */
1687 if (code == NOP_EXPR || code == CONVERT_EXPR)
1689 tree inner_type = TREE_TYPE (op0);
1690 tree outer_type = TREE_TYPE (expr);
1692 /* If VR0 represents a simple range, then try to convert
1693 the min and max values for the range to the same type
1694 as OUTER_TYPE. If the results compare equal to VR0's
1695 min and max values and the new min is still less than
1696 or equal to the new max, then we can safely use the newly
1697 computed range for EXPR. This allows us to compute
1698 accurate ranges through many casts. */
1699 if (vr0.type == VR_RANGE
1700 || (vr0.type == VR_VARYING
1701 && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type)))
1703 tree new_min, new_max, orig_min, orig_max;
1705 /* Convert the input operand min/max to OUTER_TYPE. If
1706 the input has no range information, then use the min/max
1707 for the input's type. */
1708 if (vr0.type == VR_RANGE)
1715 orig_min = TYPE_MIN_VALUE (inner_type);
1716 orig_max = TYPE_MAX_VALUE (inner_type);
1719 new_min = fold_convert (outer_type, orig_min);
1720 new_max = fold_convert (outer_type, orig_max);
1722 /* Verify the new min/max values are gimple values and
1723 that they compare equal to the original input's
1725 if (is_gimple_val (new_min)
1726 && is_gimple_val (new_max)
1727 && tree_int_cst_equal (new_min, orig_min)
1728 && tree_int_cst_equal (new_max, orig_max)
1729 && compare_values (new_min, new_max) <= 0
1730 && compare_values (new_min, new_max) >= -1)
1732 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
1737 /* When converting types of different sizes, set the result to
1738 VARYING. Things like sign extensions and precision loss may
1739 change the range. For instance, if x_3 is of type 'long long
1740 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1741 is impossible to know at compile time whether y_5 will be
1743 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
1744 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
1746 set_value_range_to_varying (vr);
1751 /* Conversion of a VR_VARYING value to a wider type can result
1752 in a usable range. So wait until after we've handled conversions
1753 before dropping the result to VR_VARYING if we had a source
1754 operand that is VR_VARYING. */
1755 if (vr0.type == VR_VARYING)
1757 set_value_range_to_varying (vr);
1761 /* Apply the operation to each end of the range and see what we end
1763 if (code == NEGATE_EXPR
1764 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1766 /* NEGATE_EXPR flips the range around. */
1767 min = (vr0.max == TYPE_MAX_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
1768 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1769 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1771 max = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
1772 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1773 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1776 else if (code == NEGATE_EXPR
1777 && TYPE_UNSIGNED (TREE_TYPE (expr)))
1779 if (!range_includes_zero_p (&vr0))
1781 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1782 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1786 if (range_is_null (&vr0))
1787 set_value_range_to_null (vr, TREE_TYPE (expr));
1789 set_value_range_to_varying (vr);
1793 else if (code == ABS_EXPR
1794 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1796 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1799 && ((vr0.type == VR_RANGE
1800 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1801 || (vr0.type == VR_ANTI_RANGE
1802 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
1803 && !range_includes_zero_p (&vr0))))
1805 set_value_range_to_varying (vr);
1809 /* ABS_EXPR may flip the range around, if the original range
1810 included negative values. */
1811 min = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1812 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1813 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1815 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1817 cmp = compare_values (min, max);
1819 /* If a VR_ANTI_RANGEs contains zero, then we have
1820 ~[-INF, min(MIN, MAX)]. */
1821 if (vr0.type == VR_ANTI_RANGE)
1823 if (range_includes_zero_p (&vr0))
1825 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
1827 /* Take the lower of the two values. */
1831 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1832 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1833 flag_wrapv is set and the original anti-range doesn't include
1834 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1835 min = (flag_wrapv && vr0.min != type_min_value
1836 ? int_const_binop (PLUS_EXPR,
1838 integer_one_node, 0)
1843 /* All else has failed, so create the range [0, INF], even for
1844 flag_wrapv since TYPE_MIN_VALUE is in the original
1846 vr0.type = VR_RANGE;
1847 min = build_int_cst (TREE_TYPE (expr), 0);
1848 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
1852 /* If the range contains zero then we know that the minimum value in the
1853 range will be zero. */
1854 else if (range_includes_zero_p (&vr0))
1858 min = build_int_cst (TREE_TYPE (expr), 0);
1862 /* If the range was reversed, swap MIN and MAX. */
1873 /* Otherwise, operate on each end of the range. */
1874 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1875 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1878 cmp = compare_values (min, max);
1879 if (cmp == -2 || cmp == 1)
1881 /* If the new range has its limits swapped around (MIN > MAX),
1882 then the operation caused one of them to wrap around, mark
1883 the new range VARYING. */
1884 set_value_range_to_varying (vr);
1887 set_value_range (vr, vr0.type, min, max, NULL);
1891 /* Extract range information from a comparison expression EXPR based
1892 on the range of its operand and the expression code. */
1895 extract_range_from_comparison (value_range_t *vr, tree expr)
1897 tree val = vrp_evaluate_conditional (expr, false);
1900 /* Since this expression was found on the RHS of an assignment,
1901 its type may be different from _Bool. Convert VAL to EXPR's
1903 val = fold_convert (TREE_TYPE (expr), val);
1904 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
1907 set_value_range_to_varying (vr);
1911 /* Try to compute a useful range out of expression EXPR and store it
1915 extract_range_from_expr (value_range_t *vr, tree expr)
1917 enum tree_code code = TREE_CODE (expr);
1919 if (code == ASSERT_EXPR)
1920 extract_range_from_assert (vr, expr);
1921 else if (code == SSA_NAME)
1922 extract_range_from_ssa_name (vr, expr);
1923 else if (TREE_CODE_CLASS (code) == tcc_binary
1924 || code == TRUTH_ANDIF_EXPR
1925 || code == TRUTH_ORIF_EXPR
1926 || code == TRUTH_AND_EXPR
1927 || code == TRUTH_OR_EXPR
1928 || code == TRUTH_XOR_EXPR)
1929 extract_range_from_binary_expr (vr, expr);
1930 else if (TREE_CODE_CLASS (code) == tcc_unary)
1931 extract_range_from_unary_expr (vr, expr);
1932 else if (TREE_CODE_CLASS (code) == tcc_comparison)
1933 extract_range_from_comparison (vr, expr);
1934 else if (is_gimple_min_invariant (expr))
1935 set_value_range (vr, VR_RANGE, expr, expr, NULL);
1937 set_value_range_to_varying (vr);
1939 /* If we got a varying range from the tests above, try a final
1940 time to derive a nonnegative or nonzero range. This time
1941 relying primarily on generic routines in fold in conjunction
1943 if (vr->type == VR_VARYING)
1945 if (INTEGRAL_TYPE_P (TREE_TYPE (expr))
1946 && vrp_expr_computes_nonnegative (expr))
1947 set_value_range_to_nonnegative (vr, TREE_TYPE (expr));
1948 else if (vrp_expr_computes_nonzero (expr))
1949 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1953 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1954 would be profitable to adjust VR using scalar evolution information
1955 for VAR. If so, update VR with the new limits. */
1958 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
1961 tree init, step, chrec;
1962 bool init_is_max, unknown_max;
1964 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1965 better opportunities than a regular range, but I'm not sure. */
1966 if (vr->type == VR_ANTI_RANGE)
1969 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
1970 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
1973 init = initial_condition_in_loop_num (chrec, loop->num);
1974 step = evolution_part_in_loop_num (chrec, loop->num);
1976 /* If STEP is symbolic, we can't know whether INIT will be the
1977 minimum or maximum value in the range. */
1978 if (step == NULL_TREE
1979 || !is_gimple_min_invariant (step))
1982 /* Do not adjust ranges when chrec may wrap. */
1983 if (scev_probably_wraps_p (chrec_type (chrec), init, step, stmt,
1984 current_loops->parray[CHREC_VARIABLE (chrec)],
1985 &init_is_max, &unknown_max)
1989 if (!POINTER_TYPE_P (TREE_TYPE (init))
1990 && (vr->type == VR_VARYING || vr->type == VR_UNDEFINED))
1992 /* For VARYING or UNDEFINED ranges, just about anything we get
1993 from scalar evolutions should be better. */
1994 tree min = TYPE_MIN_VALUE (TREE_TYPE (init));
1995 tree max = TYPE_MAX_VALUE (TREE_TYPE (init));
2002 /* If we would create an invalid range, then just assume we
2003 know absolutely nothing. This may be over-conservative,
2004 but it's clearly safe. */
2005 if (compare_values (min, max) == 1)
2008 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2010 else if (vr->type == VR_RANGE)
2017 /* INIT is the maximum value. If INIT is lower than VR->MAX
2018 but no smaller than VR->MIN, set VR->MAX to INIT. */
2019 if (compare_values (init, max) == -1)
2023 /* If we just created an invalid range with the minimum
2024 greater than the maximum, take the minimum all the
2026 if (compare_values (min, max) == 1)
2027 min = TYPE_MIN_VALUE (TREE_TYPE (min));
2032 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2033 if (compare_values (init, min) == 1)
2037 /* If we just created an invalid range with the minimum
2038 greater than the maximum, take the maximum all the
2040 if (compare_values (min, max) == 1)
2041 max = TYPE_MAX_VALUE (TREE_TYPE (max));
2045 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2050 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2052 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2053 all the values in the ranges.
2055 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2057 - Return NULL_TREE if it is not always possible to determine the
2058 value of the comparison. */
2062 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1)
2064 /* VARYING or UNDEFINED ranges cannot be compared. */
2065 if (vr0->type == VR_VARYING
2066 || vr0->type == VR_UNDEFINED
2067 || vr1->type == VR_VARYING
2068 || vr1->type == VR_UNDEFINED)
2071 /* Anti-ranges need to be handled separately. */
2072 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
2074 /* If both are anti-ranges, then we cannot compute any
2076 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
2079 /* These comparisons are never statically computable. */
2086 /* Equality can be computed only between a range and an
2087 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2088 if (vr0->type == VR_RANGE)
2090 /* To simplify processing, make VR0 the anti-range. */
2091 value_range_t *tmp = vr0;
2096 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
2098 if (compare_values (vr0->min, vr1->min) == 0
2099 && compare_values (vr0->max, vr1->max) == 0)
2100 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2105 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2106 operands around and change the comparison code. */
2107 if (comp == GT_EXPR || comp == GE_EXPR)
2110 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
2116 if (comp == EQ_EXPR)
2118 /* Equality may only be computed if both ranges represent
2119 exactly one value. */
2120 if (compare_values (vr0->min, vr0->max) == 0
2121 && compare_values (vr1->min, vr1->max) == 0)
2123 int cmp_min = compare_values (vr0->min, vr1->min);
2124 int cmp_max = compare_values (vr0->max, vr1->max);
2125 if (cmp_min == 0 && cmp_max == 0)
2126 return boolean_true_node;
2127 else if (cmp_min != -2 && cmp_max != -2)
2128 return boolean_false_node;
2130 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2131 else if (compare_values (vr0->min, vr1->max) == 1
2132 || compare_values (vr1->min, vr0->max) == 1)
2133 return boolean_false_node;
2137 else if (comp == NE_EXPR)
2141 /* If VR0 is completely to the left or completely to the right
2142 of VR1, they are always different. Notice that we need to
2143 make sure that both comparisons yield similar results to
2144 avoid comparing values that cannot be compared at
2146 cmp1 = compare_values (vr0->max, vr1->min);
2147 cmp2 = compare_values (vr0->min, vr1->max);
2148 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
2149 return boolean_true_node;
2151 /* If VR0 and VR1 represent a single value and are identical,
2153 else if (compare_values (vr0->min, vr0->max) == 0
2154 && compare_values (vr1->min, vr1->max) == 0
2155 && compare_values (vr0->min, vr1->min) == 0
2156 && compare_values (vr0->max, vr1->max) == 0)
2157 return boolean_false_node;
2159 /* Otherwise, they may or may not be different. */
2163 else if (comp == LT_EXPR || comp == LE_EXPR)
2167 /* If VR0 is to the left of VR1, return true. */
2168 tst = compare_values (vr0->max, vr1->min);
2169 if ((comp == LT_EXPR && tst == -1)
2170 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2171 return boolean_true_node;
2173 /* If VR0 is to the right of VR1, return false. */
2174 tst = compare_values (vr0->min, vr1->max);
2175 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2176 || (comp == LE_EXPR && tst == 1))
2177 return boolean_false_node;
2179 /* Otherwise, we don't know. */
2187 /* Given a value range VR, a value VAL and a comparison code COMP, return
2188 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2189 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2190 always returns false. Return NULL_TREE if it is not always
2191 possible to determine the value of the comparison. */
2194 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val)
2196 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2199 /* Anti-ranges need to be handled separately. */
2200 if (vr->type == VR_ANTI_RANGE)
2202 /* For anti-ranges, the only predicates that we can compute at
2203 compile time are equality and inequality. */
2210 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2211 if (value_inside_range (val, vr) == 1)
2212 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2217 if (comp == EQ_EXPR)
2219 /* EQ_EXPR may only be computed if VR represents exactly
2221 if (compare_values (vr->min, vr->max) == 0)
2223 int cmp = compare_values (vr->min, val);
2225 return boolean_true_node;
2226 else if (cmp == -1 || cmp == 1 || cmp == 2)
2227 return boolean_false_node;
2229 else if (compare_values (val, vr->min) == -1
2230 || compare_values (vr->max, val) == -1)
2231 return boolean_false_node;
2235 else if (comp == NE_EXPR)
2237 /* If VAL is not inside VR, then they are always different. */
2238 if (compare_values (vr->max, val) == -1
2239 || compare_values (vr->min, val) == 1)
2240 return boolean_true_node;
2242 /* If VR represents exactly one value equal to VAL, then return
2244 if (compare_values (vr->min, vr->max) == 0
2245 && compare_values (vr->min, val) == 0)
2246 return boolean_false_node;
2248 /* Otherwise, they may or may not be different. */
2251 else if (comp == LT_EXPR || comp == LE_EXPR)
2255 /* If VR is to the left of VAL, return true. */
2256 tst = compare_values (vr->max, val);
2257 if ((comp == LT_EXPR && tst == -1)
2258 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2259 return boolean_true_node;
2261 /* If VR is to the right of VAL, return false. */
2262 tst = compare_values (vr->min, val);
2263 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2264 || (comp == LE_EXPR && tst == 1))
2265 return boolean_false_node;
2267 /* Otherwise, we don't know. */
2270 else if (comp == GT_EXPR || comp == GE_EXPR)
2274 /* If VR is to the right of VAL, return true. */
2275 tst = compare_values (vr->min, val);
2276 if ((comp == GT_EXPR && tst == 1)
2277 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
2278 return boolean_true_node;
2280 /* If VR is to the left of VAL, return false. */
2281 tst = compare_values (vr->max, val);
2282 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
2283 || (comp == GE_EXPR && tst == -1))
2284 return boolean_false_node;
2286 /* Otherwise, we don't know. */
2294 /* Debugging dumps. */
2296 void dump_value_range (FILE *, value_range_t *);
2297 void debug_value_range (value_range_t *);
2298 void dump_all_value_ranges (FILE *);
2299 void debug_all_value_ranges (void);
2300 void dump_vr_equiv (FILE *, bitmap);
2301 void debug_vr_equiv (bitmap);
2304 /* Dump value range VR to FILE. */
2307 dump_value_range (FILE *file, value_range_t *vr)
2310 fprintf (file, "[]");
2311 else if (vr->type == VR_UNDEFINED)
2312 fprintf (file, "UNDEFINED");
2313 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
2315 tree type = TREE_TYPE (vr->min);
2317 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
2319 if (INTEGRAL_TYPE_P (type)
2320 && !TYPE_UNSIGNED (type)
2321 && vr->min == TYPE_MIN_VALUE (type))
2322 fprintf (file, "-INF");
2324 print_generic_expr (file, vr->min, 0);
2326 fprintf (file, ", ");
2328 if (INTEGRAL_TYPE_P (type)
2329 && vr->max == TYPE_MAX_VALUE (type))
2330 fprintf (file, "+INF");
2332 print_generic_expr (file, vr->max, 0);
2334 fprintf (file, "]");
2341 fprintf (file, " EQUIVALENCES: { ");
2343 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
2345 print_generic_expr (file, ssa_name (i), 0);
2346 fprintf (file, " ");
2350 fprintf (file, "} (%u elements)", c);
2353 else if (vr->type == VR_VARYING)
2354 fprintf (file, "VARYING");
2356 fprintf (file, "INVALID RANGE");
2360 /* Dump value range VR to stderr. */
2363 debug_value_range (value_range_t *vr)
2365 dump_value_range (stderr, vr);
2369 /* Dump value ranges of all SSA_NAMEs to FILE. */
2372 dump_all_value_ranges (FILE *file)
2376 for (i = 0; i < num_ssa_names; i++)
2380 print_generic_expr (file, ssa_name (i), 0);
2381 fprintf (file, ": ");
2382 dump_value_range (file, vr_value[i]);
2383 fprintf (file, "\n");
2387 fprintf (file, "\n");
2391 /* Dump all value ranges to stderr. */
2394 debug_all_value_ranges (void)
2396 dump_all_value_ranges (stderr);
2400 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
2401 create a new SSA name N and return the assertion assignment
2402 'V = ASSERT_EXPR <V, V OP W>'. */
2405 build_assert_expr_for (tree cond, tree v)
2409 gcc_assert (TREE_CODE (v) == SSA_NAME);
2410 n = duplicate_ssa_name (v, NULL_TREE);
2412 if (COMPARISON_CLASS_P (cond))
2414 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
2415 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, a);
2417 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
2419 /* Given !V, build the assignment N = false. */
2420 tree op0 = TREE_OPERAND (cond, 0);
2421 gcc_assert (op0 == v);
2422 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_false_node);
2424 else if (TREE_CODE (cond) == SSA_NAME)
2426 /* Given V, build the assignment N = true. */
2427 gcc_assert (v == cond);
2428 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_true_node);
2433 SSA_NAME_DEF_STMT (n) = assertion;
2435 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
2436 operand of the ASSERT_EXPR. Register the new name and the old one
2437 in the replacement table so that we can fix the SSA web after
2438 adding all the ASSERT_EXPRs. */
2439 register_new_name_mapping (n, v);
2445 /* Return false if EXPR is a predicate expression involving floating
2449 fp_predicate (tree expr)
2451 return (COMPARISON_CLASS_P (expr)
2452 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
2456 /* If the range of values taken by OP can be inferred after STMT executes,
2457 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2458 describes the inferred range. Return true if a range could be
2462 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
2465 *comp_code_p = ERROR_MARK;
2467 /* Do not attempt to infer anything in names that flow through
2469 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
2472 /* Similarly, don't infer anything from statements that may throw
2474 if (tree_could_throw_p (stmt))
2477 /* If STMT is the last statement of a basic block with no
2478 successors, there is no point inferring anything about any of its
2479 operands. We would not be able to find a proper insertion point
2480 for the assertion, anyway. */
2481 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
2484 /* We can only assume that a pointer dereference will yield
2485 non-NULL if -fdelete-null-pointer-checks is enabled. */
2486 if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op)))
2489 unsigned num_uses, num_derefs;
2491 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
2494 *val_p = build_int_cst (TREE_TYPE (op), 0);
2495 *comp_code_p = NE_EXPR;
2504 void dump_asserts_for (FILE *, tree);
2505 void debug_asserts_for (tree);
2506 void dump_all_asserts (FILE *);
2507 void debug_all_asserts (void);
2509 /* Dump all the registered assertions for NAME to FILE. */
2512 dump_asserts_for (FILE *file, tree name)
2516 fprintf (file, "Assertions to be inserted for ");
2517 print_generic_expr (file, name, 0);
2518 fprintf (file, "\n");
2520 loc = asserts_for[SSA_NAME_VERSION (name)];
2523 fprintf (file, "\t");
2524 print_generic_expr (file, bsi_stmt (loc->si), 0);
2525 fprintf (file, "\n\tBB #%d", loc->bb->index);
2528 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
2529 loc->e->dest->index);
2530 dump_edge_info (file, loc->e, 0);
2532 fprintf (file, "\n\tPREDICATE: ");
2533 print_generic_expr (file, name, 0);
2534 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
2535 print_generic_expr (file, loc->val, 0);
2536 fprintf (file, "\n\n");
2540 fprintf (file, "\n");
2544 /* Dump all the registered assertions for NAME to stderr. */
2547 debug_asserts_for (tree name)
2549 dump_asserts_for (stderr, name);
2553 /* Dump all the registered assertions for all the names to FILE. */
2556 dump_all_asserts (FILE *file)
2561 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
2562 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2563 dump_asserts_for (file, ssa_name (i));
2564 fprintf (file, "\n");
2568 /* Dump all the registered assertions for all the names to stderr. */
2571 debug_all_asserts (void)
2573 dump_all_asserts (stderr);
2577 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2578 'NAME COMP_CODE VAL' at a location that dominates block BB or
2579 E->DEST, then register this location as a possible insertion point
2580 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2582 BB, E and SI provide the exact insertion point for the new
2583 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2584 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2585 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2586 must not be NULL. */
2589 register_new_assert_for (tree name,
2590 enum tree_code comp_code,
2594 block_stmt_iterator si)
2596 assert_locus_t n, loc, last_loc;
2598 basic_block dest_bb;
2600 #if defined ENABLE_CHECKING
2601 gcc_assert (bb == NULL || e == NULL);
2604 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
2605 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
2608 /* The new assertion A will be inserted at BB or E. We need to
2609 determine if the new location is dominated by a previously
2610 registered location for A. If we are doing an edge insertion,
2611 assume that A will be inserted at E->DEST. Note that this is not
2614 If E is a critical edge, it will be split. But even if E is
2615 split, the new block will dominate the same set of blocks that
2618 The reverse, however, is not true, blocks dominated by E->DEST
2619 will not be dominated by the new block created to split E. So,
2620 if the insertion location is on a critical edge, we will not use
2621 the new location to move another assertion previously registered
2622 at a block dominated by E->DEST. */
2623 dest_bb = (bb) ? bb : e->dest;
2625 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2626 VAL at a block dominating DEST_BB, then we don't need to insert a new
2627 one. Similarly, if the same assertion already exists at a block
2628 dominated by DEST_BB and the new location is not on a critical
2629 edge, then update the existing location for the assertion (i.e.,
2630 move the assertion up in the dominance tree).
2632 Note, this is implemented as a simple linked list because there
2633 should not be more than a handful of assertions registered per
2634 name. If this becomes a performance problem, a table hashed by
2635 COMP_CODE and VAL could be implemented. */
2636 loc = asserts_for[SSA_NAME_VERSION (name)];
2641 if (loc->comp_code == comp_code
2643 || operand_equal_p (loc->val, val, 0)))
2645 /* If the assertion NAME COMP_CODE VAL has already been
2646 registered at a basic block that dominates DEST_BB, then
2647 we don't need to insert the same assertion again. Note
2648 that we don't check strict dominance here to avoid
2649 replicating the same assertion inside the same basic
2650 block more than once (e.g., when a pointer is
2651 dereferenced several times inside a block).
2653 An exception to this rule are edge insertions. If the
2654 new assertion is to be inserted on edge E, then it will
2655 dominate all the other insertions that we may want to
2656 insert in DEST_BB. So, if we are doing an edge
2657 insertion, don't do this dominance check. */
2659 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
2662 /* Otherwise, if E is not a critical edge and DEST_BB
2663 dominates the existing location for the assertion, move
2664 the assertion up in the dominance tree by updating its
2665 location information. */
2666 if ((e == NULL || !EDGE_CRITICAL_P (e))
2667 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
2676 /* Update the last node of the list and move to the next one. */
2681 /* If we didn't find an assertion already registered for
2682 NAME COMP_CODE VAL, add a new one at the end of the list of
2683 assertions associated with NAME. */
2684 n = XNEW (struct assert_locus_d);
2688 n->comp_code = comp_code;
2695 asserts_for[SSA_NAME_VERSION (name)] = n;
2697 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
2701 /* Try to register an edge assertion for SSA name NAME on edge E for
2702 the conditional jump pointed to by SI. Return true if an assertion
2703 for NAME could be registered. */
2706 register_edge_assert_for (tree name, edge e, block_stmt_iterator si)
2709 enum tree_code comp_code;
2711 stmt = bsi_stmt (si);
2713 /* Do not attempt to infer anything in names that flow through
2715 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
2718 /* If NAME was not found in the sub-graph reachable from E, then
2719 there's nothing to do. */
2720 if (!TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
2723 /* We found a use of NAME in the sub-graph rooted at E->DEST.
2724 Register an assertion for NAME according to the value that NAME
2726 if (TREE_CODE (stmt) == COND_EXPR)
2728 /* If BB ends in a COND_EXPR then NAME then we should insert
2729 the original predicate on EDGE_TRUE_VALUE and the
2730 opposite predicate on EDGE_FALSE_VALUE. */
2731 tree cond = COND_EXPR_COND (stmt);
2732 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
2734 /* Predicates may be a single SSA name or NAME OP VAL. */
2737 /* If the predicate is a name, it must be NAME, in which
2738 case we create the predicate NAME == true or
2739 NAME == false accordingly. */
2740 comp_code = EQ_EXPR;
2741 val = (is_else_edge) ? boolean_false_node : boolean_true_node;
2745 /* Otherwise, we have a comparison of the form NAME COMP VAL
2746 or VAL COMP NAME. */
2747 if (name == TREE_OPERAND (cond, 1))
2749 /* If the predicate is of the form VAL COMP NAME, flip
2750 COMP around because we need to register NAME as the
2751 first operand in the predicate. */
2752 comp_code = swap_tree_comparison (TREE_CODE (cond));
2753 val = TREE_OPERAND (cond, 0);
2757 /* The comparison is of the form NAME COMP VAL, so the
2758 comparison code remains unchanged. */
2759 comp_code = TREE_CODE (cond);
2760 val = TREE_OPERAND (cond, 1);
2763 /* If we are inserting the assertion on the ELSE edge, we
2764 need to invert the sign comparison. */
2766 comp_code = invert_tree_comparison (comp_code, 0);
2768 /* Do not register always-false predicates. FIXME, this
2769 works around a limitation in fold() when dealing with
2770 enumerations. Given 'enum { N1, N2 } x;', fold will not
2771 fold 'if (x > N2)' to 'if (0)'. */
2772 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
2773 && (INTEGRAL_TYPE_P (TREE_TYPE (val))
2774 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (val))))
2776 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
2777 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
2779 if (comp_code == GT_EXPR && compare_values (val, max) == 0)
2782 if (comp_code == LT_EXPR && compare_values (val, min) == 0)
2789 /* FIXME. Handle SWITCH_EXPR. */
2793 register_new_assert_for (name, comp_code, val, NULL, e, si);
2798 static bool find_assert_locations (basic_block bb);
2800 /* Determine whether the outgoing edges of BB should receive an
2801 ASSERT_EXPR for each of the operands of BB's last statement. The
2802 last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2804 If any of the sub-graphs rooted at BB have an interesting use of
2805 the predicate operands, an assert location node is added to the
2806 list of assertions for the corresponding operands. */
2809 find_conditional_asserts (basic_block bb)
2812 block_stmt_iterator last_si;
2818 need_assert = false;
2819 last_si = bsi_last (bb);
2820 last = bsi_stmt (last_si);
2822 /* Look for uses of the operands in each of the sub-graphs
2823 rooted at BB. We need to check each of the outgoing edges
2824 separately, so that we know what kind of ASSERT_EXPR to
2826 FOR_EACH_EDGE (e, ei, bb->succs)
2831 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
2832 Otherwise, when we finish traversing each of the sub-graphs, we
2833 won't know whether the variables were found in the sub-graphs or
2834 if they had been found in a block upstream from BB.
2836 This is actually a bad idea is some cases, particularly jump
2837 threading. Consider a CFG like the following:
2847 Assume that one or more operands in the conditional at the
2848 end of block 0 are used in a conditional in block 2, but not
2849 anywhere in block 1. In this case we will not insert any
2850 assert statements in block 1, which may cause us to miss
2851 opportunities to optimize, particularly for jump threading. */
2852 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2853 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2855 /* Traverse the strictly dominated sub-graph rooted at E->DEST
2856 to determine if any of the operands in the conditional
2857 predicate are used. */
2859 need_assert |= find_assert_locations (e->dest);
2861 /* Register the necessary assertions for each operand in the
2862 conditional predicate. */
2863 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2864 need_assert |= register_edge_assert_for (op, e, last_si);
2867 /* Finally, indicate that we have found the operands in the
2869 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2870 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2876 /* Traverse all the statements in block BB looking for statements that
2877 may generate useful assertions for the SSA names in their operand.
2878 If a statement produces a useful assertion A for name N_i, then the
2879 list of assertions already generated for N_i is scanned to
2880 determine if A is actually needed.
2882 If N_i already had the assertion A at a location dominating the
2883 current location, then nothing needs to be done. Otherwise, the
2884 new location for A is recorded instead.
2886 1- For every statement S in BB, all the variables used by S are
2887 added to bitmap FOUND_IN_SUBGRAPH.
2889 2- If statement S uses an operand N in a way that exposes a known
2890 value range for N, then if N was not already generated by an
2891 ASSERT_EXPR, create a new assert location for N. For instance,
2892 if N is a pointer and the statement dereferences it, we can
2893 assume that N is not NULL.
2895 3- COND_EXPRs are a special case of #2. We can derive range
2896 information from the predicate but need to insert different
2897 ASSERT_EXPRs for each of the sub-graphs rooted at the
2898 conditional block. If the last statement of BB is a conditional
2899 expression of the form 'X op Y', then
2901 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
2903 b) If the conditional is the only entry point to the sub-graph
2904 corresponding to the THEN_CLAUSE, recurse into it. On
2905 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
2906 an ASSERT_EXPR is added for the corresponding variable.
2908 c) Repeat step (b) on the ELSE_CLAUSE.
2910 d) Mark X and Y in FOUND_IN_SUBGRAPH.
2919 In this case, an assertion on the THEN clause is useful to
2920 determine that 'a' is always 9 on that edge. However, an assertion
2921 on the ELSE clause would be unnecessary.
2923 4- If BB does not end in a conditional expression, then we recurse
2924 into BB's dominator children.
2926 At the end of the recursive traversal, every SSA name will have a
2927 list of locations where ASSERT_EXPRs should be added. When a new
2928 location for name N is found, it is registered by calling
2929 register_new_assert_for. That function keeps track of all the
2930 registered assertions to prevent adding unnecessary assertions.
2931 For instance, if a pointer P_4 is dereferenced more than once in a
2932 dominator tree, only the location dominating all the dereference of
2933 P_4 will receive an ASSERT_EXPR.
2935 If this function returns true, then it means that there are names
2936 for which we need to generate ASSERT_EXPRs. Those assertions are
2937 inserted by process_assert_insertions.
2939 TODO. Handle SWITCH_EXPR. */
2942 find_assert_locations (basic_block bb)
2944 block_stmt_iterator si;
2949 if (TEST_BIT (blocks_visited, bb->index))
2952 SET_BIT (blocks_visited, bb->index);
2954 need_assert = false;
2956 /* Traverse all PHI nodes in BB marking used operands. */
2957 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
2959 use_operand_p arg_p;
2962 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
2964 tree arg = USE_FROM_PTR (arg_p);
2965 if (TREE_CODE (arg) == SSA_NAME)
2967 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
2968 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
2973 /* Traverse all the statements in BB marking used names and looking
2974 for statements that may infer assertions for their used operands. */
2976 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
2981 stmt = bsi_stmt (si);
2983 /* See if we can derive an assertion for any of STMT's operands. */
2984 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
2987 enum tree_code comp_code;
2989 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
2990 the sub-graph of a conditional block, when we return from
2991 this recursive walk, our parent will use the
2992 FOUND_IN_SUBGRAPH bitset to determine if one of the
2993 operands it was looking for was present in the sub-graph. */
2994 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2996 /* If OP is used in such a way that we can infer a value
2997 range for it, and we don't find a previous assertion for
2998 it, create a new assertion location node for OP. */
2999 if (infer_value_range (stmt, op, &comp_code, &value))
3001 /* If we are able to infer a nonzero value range for OP,
3002 then walk backwards through the use-def chain to see if OP
3003 was set via a typecast.
3005 If so, then we can also infer a nonzero value range
3006 for the operand of the NOP_EXPR. */
3007 if (comp_code == NE_EXPR && integer_zerop (value))
3010 tree def_stmt = SSA_NAME_DEF_STMT (t);
3012 while (TREE_CODE (def_stmt) == MODIFY_EXPR
3013 && TREE_CODE (TREE_OPERAND (def_stmt, 1)) == NOP_EXPR
3014 && TREE_CODE (TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 0)) == SSA_NAME
3015 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 0))))
3017 t = TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 0);
3018 def_stmt = SSA_NAME_DEF_STMT (t);
3020 /* Note we want to register the assert for the
3021 operand of the NOP_EXPR after SI, not after the
3023 if (! has_single_use (t))
3025 register_new_assert_for (t, comp_code, value,
3032 /* If OP is used only once, namely in this STMT, don't
3033 bother creating an ASSERT_EXPR for it. Such an
3034 ASSERT_EXPR would do nothing but increase compile time. */
3035 if (!has_single_use (op))
3037 register_new_assert_for (op, comp_code, value, bb, NULL, si);
3043 /* Remember the last statement of the block. */
3047 /* If BB's last statement is a conditional expression
3048 involving integer operands, recurse into each of the sub-graphs
3049 rooted at BB to determine if we need to add ASSERT_EXPRs. */
3051 && TREE_CODE (last) == COND_EXPR
3052 && !fp_predicate (COND_EXPR_COND (last))
3053 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
3054 need_assert |= find_conditional_asserts (bb);
3056 /* Recurse into the dominator children of BB. */
3057 for (son = first_dom_son (CDI_DOMINATORS, bb);
3059 son = next_dom_son (CDI_DOMINATORS, son))
3060 need_assert |= find_assert_locations (son);
3066 /* Create an ASSERT_EXPR for NAME and insert it in the location
3067 indicated by LOC. Return true if we made any edge insertions. */
3070 process_assert_insertions_for (tree name, assert_locus_t loc)
3072 /* Build the comparison expression NAME_i COMP_CODE VAL. */
3073 tree stmt, cond, assert_expr;
3077 cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
3078 assert_expr = build_assert_expr_for (cond, name);
3082 /* We have been asked to insert the assertion on an edge. This
3083 is used only by COND_EXPR and SWITCH_EXPR assertions. */
3084 #if defined ENABLE_CHECKING
3085 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
3086 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
3089 bsi_insert_on_edge (loc->e, assert_expr);
3093 /* Otherwise, we can insert right after LOC->SI iff the
3094 statement must not be the last statement in the block. */
3095 stmt = bsi_stmt (loc->si);
3096 if (!stmt_ends_bb_p (stmt))
3098 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
3102 /* If STMT must be the last statement in BB, we can only insert new
3103 assertions on the non-abnormal edge out of BB. Note that since
3104 STMT is not control flow, there may only be one non-abnormal edge
3106 FOR_EACH_EDGE (e, ei, loc->bb->succs)
3107 if (!(e->flags & EDGE_ABNORMAL))
3109 bsi_insert_on_edge (e, assert_expr);
3117 /* Process all the insertions registered for every name N_i registered
3118 in NEED_ASSERT_FOR. The list of assertions to be inserted are
3119 found in ASSERTS_FOR[i]. */
3122 process_assert_insertions (void)
3126 bool update_edges_p = false;
3127 int num_asserts = 0;
3129 if (dump_file && (dump_flags & TDF_DETAILS))
3130 dump_all_asserts (dump_file);
3132 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3134 assert_locus_t loc = asserts_for[i];
3139 assert_locus_t next = loc->next;
3140 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
3148 bsi_commit_edge_inserts ();
3150 if (dump_file && (dump_flags & TDF_STATS))
3151 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
3156 /* Traverse the flowgraph looking for conditional jumps to insert range
3157 expressions. These range expressions are meant to provide information
3158 to optimizations that need to reason in terms of value ranges. They
3159 will not be expanded into RTL. For instance, given:
3168 this pass will transform the code into:
3174 x = ASSERT_EXPR <x, x < y>
3179 y = ASSERT_EXPR <y, x <= y>
3183 The idea is that once copy and constant propagation have run, other
3184 optimizations will be able to determine what ranges of values can 'x'
3185 take in different paths of the code, simply by checking the reaching
3186 definition of 'x'. */
3189 insert_range_assertions (void)
3195 found_in_subgraph = sbitmap_alloc (num_ssa_names);
3196 sbitmap_zero (found_in_subgraph);
3198 blocks_visited = sbitmap_alloc (last_basic_block);
3199 sbitmap_zero (blocks_visited);
3201 need_assert_for = BITMAP_ALLOC (NULL);
3202 asserts_for = XNEWVEC (assert_locus_t, num_ssa_names);
3203 memset (asserts_for, 0, num_ssa_names * sizeof (assert_locus_t));
3205 calculate_dominance_info (CDI_DOMINATORS);
3207 update_ssa_p = false;
3208 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3209 if (find_assert_locations (e->dest))
3210 update_ssa_p = true;
3214 process_assert_insertions ();
3215 update_ssa (TODO_update_ssa_no_phi);
3218 if (dump_file && (dump_flags & TDF_DETAILS))
3220 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
3221 dump_function_to_file (current_function_decl, dump_file, dump_flags);
3224 sbitmap_free (found_in_subgraph);
3226 BITMAP_FREE (need_assert_for);
3230 /* Convert range assertion expressions into the implied copies and
3231 copy propagate away the copies. Doing the trivial copy propagation
3232 here avoids the need to run the full copy propagation pass after
3235 FIXME, this will eventually lead to copy propagation removing the
3236 names that had useful range information attached to them. For
3237 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
3238 then N_i will have the range [3, +INF].
3240 However, by converting the assertion into the implied copy
3241 operation N_i = N_j, we will then copy-propagate N_j into the uses
3242 of N_i and lose the range information. We may want to hold on to
3243 ASSERT_EXPRs a little while longer as the ranges could be used in
3244 things like jump threading.
3246 The problem with keeping ASSERT_EXPRs around is that passes after
3247 VRP need to handle them appropriately.
3249 Another approach would be to make the range information a first
3250 class property of the SSA_NAME so that it can be queried from
3251 any pass. This is made somewhat more complex by the need for
3252 multiple ranges to be associated with one SSA_NAME. */
3255 remove_range_assertions (void)
3258 block_stmt_iterator si;
3260 /* Note that the BSI iterator bump happens at the bottom of the
3261 loop and no bump is necessary if we're removing the statement
3262 referenced by the current BSI. */
3264 for (si = bsi_start (bb); !bsi_end_p (si);)
3266 tree stmt = bsi_stmt (si);
3269 if (TREE_CODE (stmt) == MODIFY_EXPR
3270 && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
3272 tree rhs = TREE_OPERAND (stmt, 1), var;
3273 tree cond = fold (ASSERT_EXPR_COND (rhs));
3274 use_operand_p use_p;
3275 imm_use_iterator iter;
3277 gcc_assert (cond != boolean_false_node);
3279 /* Propagate the RHS into every use of the LHS. */
3280 var = ASSERT_EXPR_VAR (rhs);
3281 FOR_EACH_IMM_USE_STMT (use_stmt, iter, TREE_OPERAND (stmt, 0))
3282 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
3284 SET_USE (use_p, var);
3285 gcc_assert (TREE_CODE (var) == SSA_NAME);
3288 /* And finally, remove the copy, it is not needed. */
3289 bsi_remove (&si, true);
3295 sbitmap_free (blocks_visited);
3299 /* Return true if STMT is interesting for VRP. */
3302 stmt_interesting_for_vrp (tree stmt)
3304 if (TREE_CODE (stmt) == PHI_NODE
3305 && is_gimple_reg (PHI_RESULT (stmt))
3306 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
3307 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
3309 else if (TREE_CODE (stmt) == MODIFY_EXPR)
3311 tree lhs = TREE_OPERAND (stmt, 0);
3312 tree rhs = TREE_OPERAND (stmt, 1);
3314 /* In general, assignments with virtual operands are not useful
3315 for deriving ranges, with the obvious exception of calls to
3316 builtin functions. */
3317 if (TREE_CODE (lhs) == SSA_NAME
3318 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3319 || POINTER_TYPE_P (TREE_TYPE (lhs)))
3320 && ((TREE_CODE (rhs) == CALL_EXPR
3321 && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR
3322 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))
3323 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)))
3324 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)))
3327 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3334 /* Initialize local data structures for VRP. */
3337 vrp_initialize (void)
3341 vr_value = XNEWVEC (value_range_t *, num_ssa_names);
3342 memset (vr_value, 0, num_ssa_names * sizeof (value_range_t *));
3346 block_stmt_iterator si;
3349 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3351 if (!stmt_interesting_for_vrp (phi))
3353 tree lhs = PHI_RESULT (phi);
3354 set_value_range_to_varying (get_value_range (lhs));
3355 DONT_SIMULATE_AGAIN (phi) = true;
3358 DONT_SIMULATE_AGAIN (phi) = false;
3361 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3363 tree stmt = bsi_stmt (si);
3365 if (!stmt_interesting_for_vrp (stmt))
3369 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
3370 set_value_range_to_varying (get_value_range (def));
3371 DONT_SIMULATE_AGAIN (stmt) = true;
3375 DONT_SIMULATE_AGAIN (stmt) = false;
3382 /* Visit assignment STMT. If it produces an interesting range, record
3383 the SSA name in *OUTPUT_P. */
3385 static enum ssa_prop_result
3386 vrp_visit_assignment (tree stmt, tree *output_p)
3391 lhs = TREE_OPERAND (stmt, 0);
3392 rhs = TREE_OPERAND (stmt, 1);
3394 /* We only keep track of ranges in integral and pointer types. */
3395 if (TREE_CODE (lhs) == SSA_NAME
3396 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3397 /* It is valid to have NULL MIN/MAX values on a type. See
3398 build_range_type. */
3399 && TYPE_MIN_VALUE (TREE_TYPE (lhs))
3400 && TYPE_MAX_VALUE (TREE_TYPE (lhs)))
3401 || POINTER_TYPE_P (TREE_TYPE (lhs))))
3404 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3406 extract_range_from_expr (&new_vr, rhs);
3408 /* If STMT is inside a loop, we may be able to know something
3409 else about the range of LHS by examining scalar evolution
3411 if (current_loops && (l = loop_containing_stmt (stmt)))
3412 adjust_range_with_scev (&new_vr, l, stmt, lhs);
3414 if (update_value_range (lhs, &new_vr))
3418 if (dump_file && (dump_flags & TDF_DETAILS))
3420 fprintf (dump_file, "Found new range for ");
3421 print_generic_expr (dump_file, lhs, 0);
3422 fprintf (dump_file, ": ");
3423 dump_value_range (dump_file, &new_vr);
3424 fprintf (dump_file, "\n\n");
3427 if (new_vr.type == VR_VARYING)
3428 return SSA_PROP_VARYING;
3430 return SSA_PROP_INTERESTING;
3433 return SSA_PROP_NOT_INTERESTING;
3436 /* Every other statement produces no useful ranges. */
3437 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3438 set_value_range_to_varying (get_value_range (def));
3440 return SSA_PROP_VARYING;
3444 /* Compare all the value ranges for names equivalent to VAR with VAL
3445 using comparison code COMP. Return the same value returned by
3446 compare_range_with_value. */
3449 compare_name_with_value (enum tree_code comp, tree var, tree val)
3456 t = retval = NULL_TREE;
3458 /* Get the set of equivalences for VAR. */
3459 e = get_value_range (var)->equiv;
3461 /* Add VAR to its own set of equivalences so that VAR's value range
3462 is processed by this loop (otherwise, we would have to replicate
3463 the body of the loop just to check VAR's value range). */
3464 bitmap_set_bit (e, SSA_NAME_VERSION (var));
3466 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
3468 value_range_t equiv_vr = *(vr_value[i]);
3470 /* If name N_i does not have a valid range, use N_i as its own
3471 range. This allows us to compare against names that may
3472 have N_i in their ranges. */
3473 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
3475 equiv_vr.type = VR_RANGE;
3476 equiv_vr.min = ssa_name (i);
3477 equiv_vr.max = ssa_name (i);
3480 t = compare_range_with_value (comp, &equiv_vr, val);
3483 /* All the ranges should compare the same against VAL. */
3484 gcc_assert (retval == NULL || t == retval);
3489 /* Remove VAR from its own equivalence set. */
3490 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
3495 /* We couldn't find a non-NULL value for the predicate. */
3500 /* Given a comparison code COMP and names N1 and N2, compare all the
3501 ranges equivalent to N1 against all the ranges equivalent to N2
3502 to determine the value of N1 COMP N2. Return the same value
3503 returned by compare_ranges. */
3506 compare_names (enum tree_code comp, tree n1, tree n2)
3510 bitmap_iterator bi1, bi2;
3513 /* Compare the ranges of every name equivalent to N1 against the
3514 ranges of every name equivalent to N2. */
3515 e1 = get_value_range (n1)->equiv;
3516 e2 = get_value_range (n2)->equiv;
3518 /* Add N1 and N2 to their own set of equivalences to avoid
3519 duplicating the body of the loop just to check N1 and N2
3521 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
3522 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
3524 /* If the equivalence sets have a common intersection, then the two
3525 names can be compared without checking their ranges. */
3526 if (bitmap_intersect_p (e1, e2))
3528 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3529 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3531 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
3533 : boolean_false_node;
3536 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3537 N2 to their own set of equivalences to avoid duplicating the body
3538 of the loop just to check N1 and N2 ranges. */
3539 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
3541 value_range_t vr1 = *(vr_value[i1]);
3543 /* If the range is VARYING or UNDEFINED, use the name itself. */
3544 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
3546 vr1.type = VR_RANGE;
3547 vr1.min = ssa_name (i1);
3548 vr1.max = ssa_name (i1);
3551 t = retval = NULL_TREE;
3552 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
3554 value_range_t vr2 = *(vr_value[i2]);
3556 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
3558 vr2.type = VR_RANGE;
3559 vr2.min = ssa_name (i2);
3560 vr2.max = ssa_name (i2);
3563 t = compare_ranges (comp, &vr1, &vr2);
3566 /* All the ranges in the equivalent sets should compare
3568 gcc_assert (retval == NULL || t == retval);
3575 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3576 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3581 /* None of the equivalent ranges are useful in computing this
3583 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3584 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3589 /* Given a conditional predicate COND, try to determine if COND yields
3590 true or false based on the value ranges of its operands. Return
3591 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3592 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3593 NULL if the conditional cannot be evaluated at compile time.
3595 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3596 the operands in COND are used when trying to compute its value.
3597 This is only used during final substitution. During propagation,
3598 we only check the range of each variable and not its equivalents. */
3601 vrp_evaluate_conditional (tree cond, bool use_equiv_p)
3603 gcc_assert (TREE_CODE (cond) == SSA_NAME
3604 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
3606 if (TREE_CODE (cond) == SSA_NAME)
3612 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node);
3615 value_range_t *vr = get_value_range (cond);
3616 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node);
3619 /* If COND has a known boolean range, return it. */
3623 /* Otherwise, if COND has a symbolic range of exactly one value,
3625 vr = get_value_range (cond);
3626 if (vr->type == VR_RANGE && vr->min == vr->max)
3631 tree op0 = TREE_OPERAND (cond, 0);
3632 tree op1 = TREE_OPERAND (cond, 1);
3634 /* We only deal with integral and pointer types. */
3635 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
3636 && !POINTER_TYPE_P (TREE_TYPE (op0)))
3641 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
3642 return compare_names (TREE_CODE (cond), op0, op1);
3643 else if (TREE_CODE (op0) == SSA_NAME)
3644 return compare_name_with_value (TREE_CODE (cond), op0, op1);
3645 else if (TREE_CODE (op1) == SSA_NAME)
3646 return compare_name_with_value (
3647 swap_tree_comparison (TREE_CODE (cond)), op1, op0);
3651 value_range_t *vr0, *vr1;
3653 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
3654 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
3657 return compare_ranges (TREE_CODE (cond), vr0, vr1);
3658 else if (vr0 && vr1 == NULL)
3659 return compare_range_with_value (TREE_CODE (cond), vr0, op1);
3660 else if (vr0 == NULL && vr1)
3661 return compare_range_with_value (
3662 swap_tree_comparison (TREE_CODE (cond)), vr1, op0);
3666 /* Anything else cannot be computed statically. */
3671 /* Visit conditional statement STMT. If we can determine which edge
3672 will be taken out of STMT's basic block, record it in
3673 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3674 SSA_PROP_VARYING. */
3676 static enum ssa_prop_result
3677 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
3681 *taken_edge_p = NULL;
3683 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3684 add ASSERT_EXPRs for them. */
3685 if (TREE_CODE (stmt) == SWITCH_EXPR)
3686 return SSA_PROP_VARYING;
3688 cond = COND_EXPR_COND (stmt);
3690 if (dump_file && (dump_flags & TDF_DETAILS))
3695 fprintf (dump_file, "\nVisiting conditional with predicate: ");
3696 print_generic_expr (dump_file, cond, 0);
3697 fprintf (dump_file, "\nWith known ranges\n");
3699 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
3701 fprintf (dump_file, "\t");
3702 print_generic_expr (dump_file, use, 0);
3703 fprintf (dump_file, ": ");
3704 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
3707 fprintf (dump_file, "\n");
3710 /* Compute the value of the predicate COND by checking the known
3711 ranges of each of its operands.
3713 Note that we cannot evaluate all the equivalent ranges here
3714 because those ranges may not yet be final and with the current
3715 propagation strategy, we cannot determine when the value ranges
3716 of the names in the equivalence set have changed.
3718 For instance, given the following code fragment
3722 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3726 Assume that on the first visit to i_14, i_5 has the temporary
3727 range [8, 8] because the second argument to the PHI function is
3728 not yet executable. We derive the range ~[0, 0] for i_14 and the
3729 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3730 the first time, since i_14 is equivalent to the range [8, 8], we
3731 determine that the predicate is always false.
3733 On the next round of propagation, i_13 is determined to be
3734 VARYING, which causes i_5 to drop down to VARYING. So, another
3735 visit to i_14 is scheduled. In this second visit, we compute the
3736 exact same range and equivalence set for i_14, namely ~[0, 0] and
3737 { i_5 }. But we did not have the previous range for i_5
3738 registered, so vrp_visit_assignment thinks that the range for
3739 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3740 is not visited again, which stops propagation from visiting
3741 statements in the THEN clause of that if().
3743 To properly fix this we would need to keep the previous range
3744 value for the names in the equivalence set. This way we would've
3745 discovered that from one visit to the other i_5 changed from
3746 range [8, 8] to VR_VARYING.
3748 However, fixing this apparent limitation may not be worth the
3749 additional checking. Testing on several code bases (GCC, DLV,
3750 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3751 4 more predicates folded in SPEC. */
3752 val = vrp_evaluate_conditional (cond, false);
3754 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
3756 if (dump_file && (dump_flags & TDF_DETAILS))
3758 fprintf (dump_file, "\nPredicate evaluates to: ");
3759 if (val == NULL_TREE)
3760 fprintf (dump_file, "DON'T KNOW\n");
3762 print_generic_stmt (dump_file, val, 0);
3765 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
3769 /* Evaluate statement STMT. If the statement produces a useful range,
3770 return SSA_PROP_INTERESTING and record the SSA name with the
3771 interesting range into *OUTPUT_P.
3773 If STMT is a conditional branch and we can determine its truth
3774 value, the taken edge is recorded in *TAKEN_EDGE_P.
3776 If STMT produces a varying value, return SSA_PROP_VARYING. */
3778 static enum ssa_prop_result
3779 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
3785 if (dump_file && (dump_flags & TDF_DETAILS))
3787 fprintf (dump_file, "\nVisiting statement:\n");
3788 print_generic_stmt (dump_file, stmt, dump_flags);
3789 fprintf (dump_file, "\n");
3792 ann = stmt_ann (stmt);
3793 if (TREE_CODE (stmt) == MODIFY_EXPR)
3795 tree rhs = TREE_OPERAND (stmt, 1);
3797 /* In general, assignments with virtual operands are not useful
3798 for deriving ranges, with the obvious exception of calls to
3799 builtin functions. */
3800 if ((TREE_CODE (rhs) == CALL_EXPR
3801 && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR
3802 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))
3803 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)))
3804 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3805 return vrp_visit_assignment (stmt, output_p);
3807 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3808 return vrp_visit_cond_stmt (stmt, taken_edge_p);
3810 /* All other statements produce nothing of interest for VRP, so mark
3811 their outputs varying and prevent further simulation. */
3812 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3813 set_value_range_to_varying (get_value_range (def));
3815 return SSA_PROP_VARYING;
3819 /* Meet operation for value ranges. Given two value ranges VR0 and
3820 VR1, store in VR0 the result of meeting VR0 and VR1.
3822 The meeting rules are as follows:
3824 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
3826 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
3827 union of VR0 and VR1. */
3830 vrp_meet (value_range_t *vr0, value_range_t *vr1)
3832 if (vr0->type == VR_UNDEFINED)
3834 copy_value_range (vr0, vr1);
3838 if (vr1->type == VR_UNDEFINED)
3840 /* Nothing to do. VR0 already has the resulting range. */
3844 if (vr0->type == VR_VARYING)
3846 /* Nothing to do. VR0 already has the resulting range. */
3850 if (vr1->type == VR_VARYING)
3852 set_value_range_to_varying (vr0);
3856 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
3858 /* If VR0 and VR1 have a non-empty intersection, compute the
3859 union of both ranges. */
3860 if (value_ranges_intersect_p (vr0, vr1))
3865 /* The lower limit of the new range is the minimum of the
3866 two ranges. If they cannot be compared, the result is
3868 cmp = compare_values (vr0->min, vr1->min);
3869 if (cmp == 0 || cmp == 1)
3875 set_value_range_to_varying (vr0);
3879 /* Similarly, the upper limit of the new range is the
3880 maximum of the two ranges. If they cannot be compared,
3881 the result is VARYING. */
3882 cmp = compare_values (vr0->max, vr1->max);
3883 if (cmp == 0 || cmp == -1)
3889 set_value_range_to_varying (vr0);
3893 /* The resulting set of equivalences is the intersection of
3895 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3896 bitmap_and_into (vr0->equiv, vr1->equiv);
3897 else if (vr0->equiv && !vr1->equiv)
3898 bitmap_clear (vr0->equiv);
3900 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
3905 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
3907 /* Two anti-ranges meet only if they are both identical. */
3908 if (compare_values (vr0->min, vr1->min) == 0
3909 && compare_values (vr0->max, vr1->max) == 0
3910 && compare_values (vr0->min, vr0->max) == 0)
3912 /* The resulting set of equivalences is the intersection of
3914 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3915 bitmap_and_into (vr0->equiv, vr1->equiv);
3916 else if (vr0->equiv && !vr1->equiv)
3917 bitmap_clear (vr0->equiv);
3922 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
3924 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
3925 meet only if the ranges have an empty intersection. The
3926 result of the meet operation is the anti-range. */
3927 if (!symbolic_range_p (vr0)
3928 && !symbolic_range_p (vr1)
3929 && !value_ranges_intersect_p (vr0, vr1))
3931 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
3932 set. We need to compute the intersection of the two
3933 equivalence sets. */
3934 if (vr1->type == VR_ANTI_RANGE)
3935 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
3937 /* The resulting set of equivalences is the intersection of
3939 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3940 bitmap_and_into (vr0->equiv, vr1->equiv);
3941 else if (vr0->equiv && !vr1->equiv)
3942 bitmap_clear (vr0->equiv);
3953 /* The two range VR0 and VR1 do not meet. Before giving up and
3954 setting the result to VARYING, see if we can at least derive a
3955 useful anti-range. FIXME, all this nonsense about distinguishing
3956 anti-ranges from ranges is necessary because of the odd
3957 semantics of range_includes_zero_p and friends. */
3958 if (!symbolic_range_p (vr0)
3959 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
3960 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
3961 && !symbolic_range_p (vr1)
3962 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
3963 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
3965 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
3967 /* Since this meet operation did not result from the meeting of
3968 two equivalent names, VR0 cannot have any equivalences. */
3970 bitmap_clear (vr0->equiv);
3973 set_value_range_to_varying (vr0);
3977 /* Visit all arguments for PHI node PHI that flow through executable
3978 edges. If a valid value range can be derived from all the incoming
3979 value ranges, set a new range for the LHS of PHI. */
3981 static enum ssa_prop_result
3982 vrp_visit_phi_node (tree phi)
3985 tree lhs = PHI_RESULT (phi);
3986 value_range_t *lhs_vr = get_value_range (lhs);
3987 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3989 copy_value_range (&vr_result, lhs_vr);
3991 if (dump_file && (dump_flags & TDF_DETAILS))
3993 fprintf (dump_file, "\nVisiting PHI node: ");
3994 print_generic_expr (dump_file, phi, dump_flags);
3997 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
3999 edge e = PHI_ARG_EDGE (phi, i);
4001 if (dump_file && (dump_flags & TDF_DETAILS))
4004 "\n Argument #%d (%d -> %d %sexecutable)\n",
4005 i, e->src->index, e->dest->index,
4006 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
4009 if (e->flags & EDGE_EXECUTABLE)
4011 tree arg = PHI_ARG_DEF (phi, i);
4012 value_range_t vr_arg;
4014 if (TREE_CODE (arg) == SSA_NAME)
4015 vr_arg = *(get_value_range (arg));
4018 vr_arg.type = VR_RANGE;
4021 vr_arg.equiv = NULL;
4024 if (dump_file && (dump_flags & TDF_DETAILS))
4026 fprintf (dump_file, "\t");
4027 print_generic_expr (dump_file, arg, dump_flags);
4028 fprintf (dump_file, "\n\tValue: ");
4029 dump_value_range (dump_file, &vr_arg);
4030 fprintf (dump_file, "\n");
4033 vrp_meet (&vr_result, &vr_arg);
4035 if (vr_result.type == VR_VARYING)
4040 if (vr_result.type == VR_VARYING)
4043 /* To prevent infinite iterations in the algorithm, derive ranges
4044 when the new value is slightly bigger or smaller than the
4046 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE)
4048 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
4050 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
4051 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
4053 /* If the new minimum is smaller or larger than the previous
4054 one, go all the way to -INF. In the first case, to avoid
4055 iterating millions of times to reach -INF, and in the
4056 other case to avoid infinite bouncing between different
4058 if (cmp_min > 0 || cmp_min < 0)
4059 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
4061 /* Similarly, if the new maximum is smaller or larger than
4062 the previous one, go all the way to +INF. */
4063 if (cmp_max < 0 || cmp_max > 0)
4064 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
4066 /* If we ended up with a (-INF, +INF) range, set it to
4068 if (vr_result.min == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))
4069 && vr_result.max == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)))
4074 /* If the new range is different than the previous value, keep
4076 if (update_value_range (lhs, &vr_result))
4077 return SSA_PROP_INTERESTING;
4079 /* Nothing changed, don't add outgoing edges. */
4080 return SSA_PROP_NOT_INTERESTING;
4082 /* No match found. Set the LHS to VARYING. */
4084 set_value_range_to_varying (lhs_vr);
4085 return SSA_PROP_VARYING;
4088 /* Simplify a division or modulo operator to a right shift or
4089 bitwise and if the first operand is unsigned or is greater
4090 than zero and the second operand is an exact power of two. */
4093 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
4096 tree op = TREE_OPERAND (rhs, 0);
4097 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
4099 if (TYPE_UNSIGNED (TREE_TYPE (op)))
4101 val = integer_one_node;
4105 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node);
4108 if (val && integer_onep (val))
4111 tree op0 = TREE_OPERAND (rhs, 0);
4112 tree op1 = TREE_OPERAND (rhs, 1);
4114 if (rhs_code == TRUNC_DIV_EXPR)
4116 t = build_int_cst (NULL_TREE, tree_log2 (op1));
4117 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
4121 t = build_int_cst (TREE_TYPE (op1), 1);
4122 t = int_const_binop (MINUS_EXPR, op1, t, 0);
4123 t = fold_convert (TREE_TYPE (op0), t);
4124 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
4127 TREE_OPERAND (stmt, 1) = t;
4132 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
4133 ABS_EXPR. If the operand is <= 0, then simplify the
4134 ABS_EXPR into a NEGATE_EXPR. */
4137 simplify_abs_using_ranges (tree stmt, tree rhs)
4140 tree op = TREE_OPERAND (rhs, 0);
4141 tree type = TREE_TYPE (op);
4142 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
4144 if (TYPE_UNSIGNED (type))
4146 val = integer_zero_node;
4150 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node);
4153 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node);
4157 if (integer_zerop (val))
4158 val = integer_one_node;
4159 else if (integer_onep (val))
4160 val = integer_zero_node;
4165 && (integer_onep (val) || integer_zerop (val)))
4169 if (integer_onep (val))
4170 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
4174 TREE_OPERAND (stmt, 1) = t;
4180 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
4181 a known value range VR.
4183 If there is one and only one value which will satisfy the
4184 conditional, then return that value. Else return NULL. */
4187 test_for_singularity (enum tree_code cond_code, tree op0,
4188 tree op1, value_range_t *vr)
4193 /* Extract minimum/maximum values which satisfy the
4194 the conditional as it was written. */
4195 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
4197 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
4200 if (cond_code == LT_EXPR)
4202 tree one = build_int_cst (TREE_TYPE (op0), 1);
4203 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
4206 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
4208 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
4211 if (cond_code == GT_EXPR)
4213 tree one = build_int_cst (TREE_TYPE (op0), 1);
4214 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
4218 /* Now refine the minimum and maximum values using any
4219 value range information we have for op0. */
4222 if (compare_values (vr->min, min) == -1)
4226 if (compare_values (vr->max, max) == 1)
4231 /* If the new min/max values have converged to a single value,
4232 then there is only one value which can satisfy the condition,
4233 return that value. */
4234 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
4240 /* Simplify a conditional using a relational operator to an equality
4241 test if the range information indicates only one value can satisfy
4242 the original conditional. */
4245 simplify_cond_using_ranges (tree stmt)
4247 tree cond = COND_EXPR_COND (stmt);
4248 tree op0 = TREE_OPERAND (cond, 0);
4249 tree op1 = TREE_OPERAND (cond, 1);
4250 enum tree_code cond_code = TREE_CODE (cond);
4252 if (cond_code != NE_EXPR
4253 && cond_code != EQ_EXPR
4254 && TREE_CODE (op0) == SSA_NAME
4255 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
4256 && is_gimple_min_invariant (op1))
4258 value_range_t *vr = get_value_range (op0);
4260 /* If we have range information for OP0, then we might be
4261 able to simplify this conditional. */
4262 if (vr->type == VR_RANGE)
4264 tree new = test_for_singularity (cond_code, op0, op1, vr);
4270 fprintf (dump_file, "Simplified relational ");
4271 print_generic_expr (dump_file, cond, 0);
4272 fprintf (dump_file, " into ");
4275 COND_EXPR_COND (stmt)
4276 = build2 (EQ_EXPR, boolean_type_node, op0, new);
4281 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4282 fprintf (dump_file, "\n");
4288 /* Try again after inverting the condition. We only deal
4289 with integral types here, so no need to worry about
4290 issues with inverting FP comparisons. */
4291 cond_code = invert_tree_comparison (cond_code, false);
4292 new = test_for_singularity (cond_code, op0, op1, vr);
4298 fprintf (dump_file, "Simplified relational ");
4299 print_generic_expr (dump_file, cond, 0);
4300 fprintf (dump_file, " into ");
4303 COND_EXPR_COND (stmt)
4304 = build2 (NE_EXPR, boolean_type_node, op0, new);
4309 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4310 fprintf (dump_file, "\n");
4319 /* Simplify STMT using ranges if possible. */
4322 simplify_stmt_using_ranges (tree stmt)
4324 if (TREE_CODE (stmt) == MODIFY_EXPR)
4326 tree rhs = TREE_OPERAND (stmt, 1);
4327 enum tree_code rhs_code = TREE_CODE (rhs);
4329 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
4330 and BIT_AND_EXPR respectively if the first operand is greater
4331 than zero and the second operand is an exact power of two. */
4332 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
4333 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
4334 && integer_pow2p (TREE_OPERAND (rhs, 1)))
4335 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
4337 /* Transform ABS (X) into X or -X as appropriate. */
4338 if (rhs_code == ABS_EXPR
4339 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
4340 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
4341 simplify_abs_using_ranges (stmt, rhs);
4343 else if (TREE_CODE (stmt) == COND_EXPR
4344 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
4346 simplify_cond_using_ranges (stmt);
4350 /* Stack of dest,src equivalency pairs that need to be restored after
4351 each attempt to thread a block's incoming edge to an outgoing edge.
4353 A NULL entry is used to mark the end of pairs which need to be
4355 static VEC(tree,heap) *stack;
4357 /* A trivial wrapper so that we can present the generic jump
4358 threading code with a simple API for simplifying statements. */
4360 simplify_stmt_for_jump_threading (tree stmt)
4362 /* We only use VRP information to simplify conditionals. This is
4363 overly conservative, but it's unclear if doing more would be
4364 worth the compile time cost. */
4365 if (TREE_CODE (stmt) != COND_EXPR)
4368 return vrp_evaluate_conditional (COND_EXPR_COND (stmt), true);
4371 /* Blocks which have more than one predecessor and more than
4372 one successor present jump threading opportunities. ie,
4373 when the block is reached from a specific predecessor, we
4374 may be able to determine which of the outgoing edges will
4375 be traversed. When this optimization applies, we are able
4376 to avoid conditionals at runtime and we may expose secondary
4377 optimization opportunities.
4379 This routine is effectively a driver for the generic jump
4380 threading code. It basically just presents the generic code
4381 with edges that may be suitable for jump threading.
4383 Unlike DOM, we do not iterate VRP if jump threading was successful.
4384 While iterating may expose new opportunities for VRP, it is expected
4385 those opportunities would be very limited and the compile time cost
4386 to expose those opportunities would be significant.
4388 As jump threading opportunities are discovered, they are registered
4389 for later realization. */
4392 identify_jump_threads (void)
4397 /* Ugh. When substituting values earlier in this pass we can
4398 wipe the dominance information. So rebuild the dominator
4399 information as we need it within the jump threading code. */
4400 calculate_dominance_info (CDI_DOMINATORS);
4402 /* We do not allow VRP information to be used for jump threading
4403 across a back edge in the CFG. Otherwise it becomes too
4404 difficult to avoid eliminating loop exit tests. Of course
4405 EDGE_DFS_BACK is not accurate at this time so we have to
4407 mark_dfs_back_edges ();
4409 /* Allocate our unwinder stack to unwind any temporary equivalences
4410 that might be recorded. */
4411 stack = VEC_alloc (tree, heap, 20);
4413 /* To avoid lots of silly node creation, we create a single
4414 conditional and just modify it in-place when attempting to
4416 dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL);
4417 dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL);
4419 /* Walk through all the blocks finding those which present a
4420 potential jump threading opportunity. We could set this up
4421 as a dominator walker and record data during the walk, but
4422 I doubt it's worth the effort for the classes of jump
4423 threading opportunities we are trying to identify at this
4424 point in compilation. */
4429 /* If the generic jump threading code does not find this block
4430 interesting, then there is nothing to do. */
4431 if (! potentially_threadable_block (bb))
4434 /* We only care about blocks ending in a COND_EXPR. While there
4435 may be some value in handling SWITCH_EXPR here, I doubt it's
4436 terribly important. */
4437 last = bsi_stmt (bsi_last (bb));
4438 if (TREE_CODE (last) != COND_EXPR)
4441 /* We're basically looking for any kind of conditional with
4442 integral type arguments. */
4443 cond = COND_EXPR_COND (last);
4444 if ((TREE_CODE (cond) == SSA_NAME
4445 && INTEGRAL_TYPE_P (TREE_TYPE (cond)))
4446 || (COMPARISON_CLASS_P (cond)
4447 && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
4448 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0)))
4449 && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME
4450 || is_gimple_min_invariant (TREE_OPERAND (cond, 1)))
4451 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
4456 /* We've got a block with multiple predecessors and multiple
4457 successors which also ends in a suitable conditional. For
4458 each predecessor, see if we can thread it to a specific
4460 FOR_EACH_EDGE (e, ei, bb->preds)
4462 /* Do not thread across back edges or abnormal edges
4464 if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
4467 thread_across_edge (dummy, e, true,
4469 simplify_stmt_for_jump_threading);
4474 /* We do not actually update the CFG or SSA graphs at this point as
4475 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
4476 handle ASSERT_EXPRs gracefully. */
4479 /* We identified all the jump threading opportunities earlier, but could
4480 not transform the CFG at that time. This routine transforms the
4481 CFG and arranges for the dominator tree to be rebuilt if necessary.
4483 Note the SSA graph update will occur during the normal TODO
4484 processing by the pass manager. */
4486 finalize_jump_threads (void)
4488 bool cfg_altered = false;
4489 cfg_altered = thread_through_all_blocks ();
4491 /* If we threaded jumps, then we need to recompute the dominance
4492 information, to safely do that we must clean up the CFG first. */
4495 free_dominance_info (CDI_DOMINATORS);
4496 cleanup_tree_cfg ();
4497 calculate_dominance_info (CDI_DOMINATORS);
4499 VEC_free (tree, heap, stack);
4503 /* Traverse all the blocks folding conditionals with known ranges. */
4509 prop_value_t *single_val_range;
4510 bool do_value_subst_p;
4514 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
4515 dump_all_value_ranges (dump_file);
4516 fprintf (dump_file, "\n");
4519 /* We may have ended with ranges that have exactly one value. Those
4520 values can be substituted as any other copy/const propagated
4521 value using substitute_and_fold. */
4522 single_val_range = XNEWVEC (prop_value_t, num_ssa_names);
4523 memset (single_val_range, 0, num_ssa_names * sizeof (*single_val_range));
4525 do_value_subst_p = false;
4526 for (i = 0; i < num_ssa_names; i++)
4528 && vr_value[i]->type == VR_RANGE
4529 && vr_value[i]->min == vr_value[i]->max)
4531 single_val_range[i].value = vr_value[i]->min;
4532 do_value_subst_p = true;
4535 if (!do_value_subst_p)
4537 /* We found no single-valued ranges, don't waste time trying to
4538 do single value substitution in substitute_and_fold. */
4539 free (single_val_range);
4540 single_val_range = NULL;
4543 substitute_and_fold (single_val_range, true);
4545 /* We must identify jump threading opportunities before we release
4546 the datastructures built by VRP. */
4547 identify_jump_threads ();
4549 /* Free allocated memory. */
4550 for (i = 0; i < num_ssa_names; i++)
4553 BITMAP_FREE (vr_value[i]->equiv);
4557 free (single_val_range);
4560 /* So that we can distinguish between VRP data being available
4561 and not available. */
4566 /* Main entry point to VRP (Value Range Propagation). This pass is
4567 loosely based on J. R. C. Patterson, ``Accurate Static Branch
4568 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
4569 Programming Language Design and Implementation, pp. 67-78, 1995.
4570 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
4572 This is essentially an SSA-CCP pass modified to deal with ranges
4573 instead of constants.
4575 While propagating ranges, we may find that two or more SSA name
4576 have equivalent, though distinct ranges. For instance,
4579 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
4581 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
4585 In the code above, pointer p_5 has range [q_2, q_2], but from the
4586 code we can also determine that p_5 cannot be NULL and, if q_2 had
4587 a non-varying range, p_5's range should also be compatible with it.
4589 These equivalences are created by two expressions: ASSERT_EXPR and
4590 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
4591 result of another assertion, then we can use the fact that p_5 and
4592 p_4 are equivalent when evaluating p_5's range.
4594 Together with value ranges, we also propagate these equivalences
4595 between names so that we can take advantage of information from
4596 multiple ranges when doing final replacement. Note that this
4597 equivalency relation is transitive but not symmetric.
4599 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
4600 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
4601 in contexts where that assertion does not hold (e.g., in line 6).
4603 TODO, the main difference between this pass and Patterson's is that
4604 we do not propagate edge probabilities. We only compute whether
4605 edges can be taken or not. That is, instead of having a spectrum
4606 of jump probabilities between 0 and 1, we only deal with 0, 1 and
4607 DON'T KNOW. In the future, it may be worthwhile to propagate
4608 probabilities to aid branch prediction. */
4613 insert_range_assertions ();
4615 current_loops = loop_optimizer_init (LOOPS_NORMAL);
4617 scev_initialize (current_loops);
4620 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
4626 loop_optimizer_finalize (current_loops);
4627 current_loops = NULL;
4630 /* ASSERT_EXPRs must be removed before finalizing jump threads
4631 as finalizing jump threads calls the CFG cleanup code which
4632 does not properly handle ASSERT_EXPRs. */
4633 remove_range_assertions ();
4635 /* If we exposed any new variables, go ahead and put them into
4636 SSA form now, before we handle jump threading. This simplifies
4637 interactions between rewriting of _DECL nodes into SSA form
4638 and rewriting SSA_NAME nodes into SSA form after block
4639 duplication and CFG manipulation. */
4640 update_ssa (TODO_update_ssa);
4642 finalize_jump_threads ();
4649 return flag_tree_vrp != 0;
4652 struct tree_opt_pass pass_vrp =
4655 gate_vrp, /* gate */
4656 execute_vrp, /* execute */
4659 0, /* static_pass_number */
4660 TV_TREE_VRP, /* tv_id */
4661 PROP_ssa | PROP_alias, /* properties_required */
4662 0, /* properties_provided */
4663 PROP_smt_usage, /* properties_destroyed */
4664 0, /* todo_flags_start */
4670 | TODO_update_smt_usage, /* todo_flags_finish */