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);
293 /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */
296 vrp_operand_equal_p (tree val1, tree val2)
300 && operand_equal_p (val1, val2, 0)));
303 /* Return true, if the bitmaps B1 and B2 are equal. */
306 vrp_bitmap_equal_p (bitmap b1, bitmap b2)
310 && bitmap_equal_p (b1, b2)));
313 /* Update the value range and equivalence set for variable VAR to
314 NEW_VR. Return true if NEW_VR is different from VAR's previous
317 NOTE: This function assumes that NEW_VR is a temporary value range
318 object created for the sole purpose of updating VAR's range. The
319 storage used by the equivalence set from NEW_VR will be freed by
320 this function. Do not call update_value_range when NEW_VR
321 is the range object associated with another SSA name. */
324 update_value_range (tree var, value_range_t *new_vr)
326 value_range_t *old_vr;
329 /* Update the value range, if necessary. */
330 old_vr = get_value_range (var);
331 is_new = old_vr->type != new_vr->type
332 || !vrp_operand_equal_p (old_vr->min, new_vr->min)
333 || !vrp_operand_equal_p (old_vr->max, new_vr->max)
334 || !vrp_bitmap_equal_p (old_vr->equiv, new_vr->equiv);
337 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
340 BITMAP_FREE (new_vr->equiv);
341 new_vr->equiv = NULL;
347 /* Add VAR and VAR's equivalence set to EQUIV. */
350 add_equivalence (bitmap equiv, tree var)
352 unsigned ver = SSA_NAME_VERSION (var);
353 value_range_t *vr = vr_value[ver];
355 bitmap_set_bit (equiv, ver);
357 bitmap_ior_into (equiv, vr->equiv);
361 /* Return true if VR is ~[0, 0]. */
364 range_is_nonnull (value_range_t *vr)
366 return vr->type == VR_ANTI_RANGE
367 && integer_zerop (vr->min)
368 && integer_zerop (vr->max);
372 /* Return true if VR is [0, 0]. */
375 range_is_null (value_range_t *vr)
377 return vr->type == VR_RANGE
378 && integer_zerop (vr->min)
379 && integer_zerop (vr->max);
383 /* Return true if value range VR involves at least one symbol. */
386 symbolic_range_p (value_range_t *vr)
388 return (!is_gimple_min_invariant (vr->min)
389 || !is_gimple_min_invariant (vr->max));
392 /* Like tree_expr_nonnegative_p, but this function uses value ranges
396 vrp_expr_computes_nonnegative (tree expr)
398 return tree_expr_nonnegative_p (expr);
401 /* Like tree_expr_nonzero_p, but this function uses value ranges
405 vrp_expr_computes_nonzero (tree expr)
407 if (tree_expr_nonzero_p (expr))
410 /* If we have an expression of the form &X->a, then the expression
411 is nonnull if X is nonnull. */
412 if (TREE_CODE (expr) == ADDR_EXPR)
414 tree base = get_base_address (TREE_OPERAND (expr, 0));
416 if (base != NULL_TREE
417 && TREE_CODE (base) == INDIRECT_REF
418 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
420 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
421 if (range_is_nonnull (vr))
429 /* Returns true if EXPR is a valid value (as expected by compare_values) --
430 a gimple invariant, or SSA_NAME +- CST. */
433 valid_value_p (tree expr)
435 if (TREE_CODE (expr) == SSA_NAME)
438 if (TREE_CODE (expr) == PLUS_EXPR
439 || TREE_CODE (expr) == MINUS_EXPR)
440 return (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME
441 && TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST);
443 return is_gimple_min_invariant (expr);
446 /* Compare two values VAL1 and VAL2. Return
448 -2 if VAL1 and VAL2 cannot be compared at compile-time,
451 +1 if VAL1 > VAL2, and
454 This is similar to tree_int_cst_compare but supports pointer values
455 and values that cannot be compared at compile time. */
458 compare_values (tree val1, tree val2)
463 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
465 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
466 == POINTER_TYPE_P (TREE_TYPE (val2)));
468 if ((TREE_CODE (val1) == SSA_NAME
469 || TREE_CODE (val1) == PLUS_EXPR
470 || TREE_CODE (val1) == MINUS_EXPR)
471 && (TREE_CODE (val2) == SSA_NAME
472 || TREE_CODE (val2) == PLUS_EXPR
473 || TREE_CODE (val2) == MINUS_EXPR))
476 enum tree_code code1, code2;
478 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
479 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
480 same name, return -2. */
481 if (TREE_CODE (val1) == SSA_NAME)
489 code1 = TREE_CODE (val1);
490 n1 = TREE_OPERAND (val1, 0);
491 c1 = TREE_OPERAND (val1, 1);
492 if (tree_int_cst_sgn (c1) == -1)
494 c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1);
497 code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
501 if (TREE_CODE (val2) == SSA_NAME)
509 code2 = TREE_CODE (val2);
510 n2 = TREE_OPERAND (val2, 0);
511 c2 = TREE_OPERAND (val2, 1);
512 if (tree_int_cst_sgn (c2) == -1)
514 c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2);
517 code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
521 /* Both values must use the same name. */
525 if (code1 == SSA_NAME
526 && code2 == SSA_NAME)
530 /* If overflow is defined we cannot simplify more. */
531 if (TYPE_UNSIGNED (TREE_TYPE (val1))
535 if (code1 == SSA_NAME)
537 if (code2 == PLUS_EXPR)
538 /* NAME < NAME + CST */
540 else if (code2 == MINUS_EXPR)
541 /* NAME > NAME - CST */
544 else if (code1 == PLUS_EXPR)
546 if (code2 == SSA_NAME)
547 /* NAME + CST > NAME */
549 else if (code2 == PLUS_EXPR)
550 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
551 return compare_values (c1, c2);
552 else if (code2 == MINUS_EXPR)
553 /* NAME + CST1 > NAME - CST2 */
556 else if (code1 == MINUS_EXPR)
558 if (code2 == SSA_NAME)
559 /* NAME - CST < NAME */
561 else if (code2 == PLUS_EXPR)
562 /* NAME - CST1 < NAME + CST2 */
564 else if (code2 == MINUS_EXPR)
565 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
566 C1 and C2 are swapped in the call to compare_values. */
567 return compare_values (c2, c1);
573 /* We cannot compare non-constants. */
574 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
577 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
579 /* We cannot compare overflowed values. */
580 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
583 return tree_int_cst_compare (val1, val2);
589 /* First see if VAL1 and VAL2 are not the same. */
590 if (val1 == val2 || operand_equal_p (val1, val2, 0))
593 /* If VAL1 is a lower address than VAL2, return -1. */
594 t = fold_binary (LT_EXPR, boolean_type_node, val1, val2);
595 if (t == boolean_true_node)
598 /* If VAL1 is a higher address than VAL2, return +1. */
599 t = fold_binary (GT_EXPR, boolean_type_node, val1, val2);
600 if (t == boolean_true_node)
603 /* If VAL1 is different than VAL2, return +2. */
604 t = fold_binary (NE_EXPR, boolean_type_node, val1, val2);
605 if (t == boolean_true_node)
613 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
614 0 if VAL is not inside VR,
615 -2 if we cannot tell either way.
617 FIXME, the current semantics of this functions are a bit quirky
618 when taken in the context of VRP. In here we do not care
619 about VR's type. If VR is the anti-range ~[3, 5] the call
620 value_inside_range (4, VR) will return 1.
622 This is counter-intuitive in a strict sense, but the callers
623 currently expect this. They are calling the function
624 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
625 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
628 This also applies to value_ranges_intersect_p and
629 range_includes_zero_p. The semantics of VR_RANGE and
630 VR_ANTI_RANGE should be encoded here, but that also means
631 adapting the users of these functions to the new semantics. */
634 value_inside_range (tree val, value_range_t *vr)
638 cmp1 = fold_binary_to_constant (GE_EXPR, boolean_type_node, val, vr->min);
642 cmp2 = fold_binary_to_constant (LE_EXPR, boolean_type_node, val, vr->max);
646 return cmp1 == boolean_true_node && cmp2 == boolean_true_node;
650 /* Return true if value ranges VR0 and VR1 have a non-empty
654 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
656 return (value_inside_range (vr1->min, vr0) == 1
657 || value_inside_range (vr1->max, vr0) == 1
658 || value_inside_range (vr0->min, vr1) == 1
659 || value_inside_range (vr0->max, vr1) == 1);
663 /* Return true if VR includes the value zero, false otherwise. FIXME,
664 currently this will return false for an anti-range like ~[-4, 3].
665 This will be wrong when the semantics of value_inside_range are
666 modified (currently the users of this function expect these
670 range_includes_zero_p (value_range_t *vr)
674 gcc_assert (vr->type != VR_UNDEFINED
675 && vr->type != VR_VARYING
676 && !symbolic_range_p (vr));
678 zero = build_int_cst (TREE_TYPE (vr->min), 0);
679 return (value_inside_range (zero, vr) == 1);
682 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
683 false otherwise or if no value range information is available. */
686 ssa_name_nonnegative_p (tree t)
688 value_range_t *vr = get_value_range (t);
693 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
694 which would return a useful value should be encoded as a VR_RANGE. */
695 if (vr->type == VR_RANGE)
697 int result = compare_values (vr->min, integer_zero_node);
699 return (result == 0 || result == 1);
704 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
705 false otherwise or if no value range information is available. */
708 ssa_name_nonzero_p (tree t)
710 value_range_t *vr = get_value_range (t);
715 /* A VR_RANGE which does not include zero is a nonzero value. */
716 if (vr->type == VR_RANGE && !symbolic_range_p (vr))
717 return ! range_includes_zero_p (vr);
719 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
720 if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr))
721 return range_includes_zero_p (vr);
727 /* Extract value range information from an ASSERT_EXPR EXPR and store
731 extract_range_from_assert (value_range_t *vr_p, tree expr)
733 tree var, cond, limit, min, max, type;
734 value_range_t *var_vr, *limit_vr;
735 enum tree_code cond_code;
737 var = ASSERT_EXPR_VAR (expr);
738 cond = ASSERT_EXPR_COND (expr);
740 gcc_assert (COMPARISON_CLASS_P (cond));
742 /* Find VAR in the ASSERT_EXPR conditional. */
743 if (var == TREE_OPERAND (cond, 0))
745 /* If the predicate is of the form VAR COMP LIMIT, then we just
746 take LIMIT from the RHS and use the same comparison code. */
747 limit = TREE_OPERAND (cond, 1);
748 cond_code = TREE_CODE (cond);
752 /* If the predicate is of the form LIMIT COMP VAR, then we need
753 to flip around the comparison code to create the proper range
755 limit = TREE_OPERAND (cond, 0);
756 cond_code = swap_tree_comparison (TREE_CODE (cond));
759 type = TREE_TYPE (limit);
760 gcc_assert (limit != var);
762 /* For pointer arithmetic, we only keep track of pointer equality
764 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
766 set_value_range_to_varying (vr_p);
770 /* If LIMIT is another SSA name and LIMIT has a range of its own,
771 try to use LIMIT's range to avoid creating symbolic ranges
773 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
775 /* LIMIT's range is only interesting if it has any useful information. */
777 && (limit_vr->type == VR_UNDEFINED
778 || limit_vr->type == VR_VARYING
779 || symbolic_range_p (limit_vr)))
782 /* Initially, the new range has the same set of equivalences of
783 VAR's range. This will be revised before returning the final
784 value. Since assertions may be chained via mutually exclusive
785 predicates, we will need to trim the set of equivalences before
787 gcc_assert (vr_p->equiv == NULL);
788 vr_p->equiv = BITMAP_ALLOC (NULL);
789 add_equivalence (vr_p->equiv, var);
791 /* Extract a new range based on the asserted comparison for VAR and
792 LIMIT's value range. Notice that if LIMIT has an anti-range, we
793 will only use it for equality comparisons (EQ_EXPR). For any
794 other kind of assertion, we cannot derive a range from LIMIT's
795 anti-range that can be used to describe the new range. For
796 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
797 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
798 no single range for x_2 that could describe LE_EXPR, so we might
799 as well build the range [b_4, +INF] for it. */
800 if (cond_code == EQ_EXPR)
802 enum value_range_type range_type;
806 range_type = limit_vr->type;
812 range_type = VR_RANGE;
817 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
819 /* When asserting the equality VAR == LIMIT and LIMIT is another
820 SSA name, the new range will also inherit the equivalence set
822 if (TREE_CODE (limit) == SSA_NAME)
823 add_equivalence (vr_p->equiv, limit);
825 else if (cond_code == NE_EXPR)
827 /* As described above, when LIMIT's range is an anti-range and
828 this assertion is an inequality (NE_EXPR), then we cannot
829 derive anything from the anti-range. For instance, if
830 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
831 not imply that VAR's range is [0, 0]. So, in the case of
832 anti-ranges, we just assert the inequality using LIMIT and
835 If LIMIT_VR is a range, we can only use it to build a new
836 anti-range if LIMIT_VR is a single-valued range. For
837 instance, if LIMIT_VR is [0, 1], the predicate
838 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
839 Rather, it means that for value 0 VAR should be ~[0, 0]
840 and for value 1, VAR should be ~[1, 1]. We cannot
841 represent these ranges.
843 The only situation in which we can build a valid
844 anti-range is when LIMIT_VR is a single-valued range
845 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
846 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
848 && limit_vr->type == VR_RANGE
849 && compare_values (limit_vr->min, limit_vr->max) == 0)
856 /* In any other case, we cannot use LIMIT's range to build a
861 /* If MIN and MAX cover the whole range for their type, then
862 just use the original LIMIT. */
863 if (INTEGRAL_TYPE_P (type)
864 && min == TYPE_MIN_VALUE (type)
865 && max == TYPE_MAX_VALUE (type))
868 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
870 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
872 min = TYPE_MIN_VALUE (type);
874 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
878 /* If LIMIT_VR is of the form [N1, N2], we need to build the
879 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
884 /* If the maximum value forces us to be out of bounds, simply punt.
885 It would be pointless to try and do anything more since this
886 all should be optimized away above us. */
887 if (cond_code == LT_EXPR && compare_values (max, min) == 0)
888 set_value_range_to_varying (vr_p);
891 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
892 if (cond_code == LT_EXPR)
894 tree one = build_int_cst (type, 1);
895 max = fold_build2 (MINUS_EXPR, type, max, one);
898 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
901 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
903 max = TYPE_MAX_VALUE (type);
905 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
909 /* If LIMIT_VR is of the form [N1, N2], we need to build the
910 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
915 /* If the minimum value forces us to be out of bounds, simply punt.
916 It would be pointless to try and do anything more since this
917 all should be optimized away above us. */
918 if (cond_code == GT_EXPR && compare_values (min, max) == 0)
919 set_value_range_to_varying (vr_p);
922 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
923 if (cond_code == GT_EXPR)
925 tree one = build_int_cst (type, 1);
926 min = fold_build2 (PLUS_EXPR, type, min, one);
929 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
935 /* If VAR already had a known range, it may happen that the new
936 range we have computed and VAR's range are not compatible. For
940 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
942 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
944 While the above comes from a faulty program, it will cause an ICE
945 later because p_8 and p_6 will have incompatible ranges and at
946 the same time will be considered equivalent. A similar situation
950 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
952 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
954 Again i_6 and i_7 will have incompatible ranges. It would be
955 pointless to try and do anything with i_7's range because
956 anything dominated by 'if (i_5 < 5)' will be optimized away.
957 Note, due to the wa in which simulation proceeds, the statement
958 i_7 = ASSERT_EXPR <...> we would never be visited because the
959 conditional 'if (i_5 < 5)' always evaluates to false. However,
960 this extra check does not hurt and may protect against future
961 changes to VRP that may get into a situation similar to the
962 NULL pointer dereference example.
964 Note that these compatibility tests are only needed when dealing
965 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
966 are both anti-ranges, they will always be compatible, because two
967 anti-ranges will always have a non-empty intersection. */
969 var_vr = get_value_range (var);
971 /* We may need to make adjustments when VR_P and VAR_VR are numeric
972 ranges or anti-ranges. */
973 if (vr_p->type == VR_VARYING
974 || vr_p->type == VR_UNDEFINED
975 || var_vr->type == VR_VARYING
976 || var_vr->type == VR_UNDEFINED
977 || symbolic_range_p (vr_p)
978 || symbolic_range_p (var_vr))
981 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
983 /* If the two ranges have a non-empty intersection, we can
984 refine the resulting range. Since the assert expression
985 creates an equivalency and at the same time it asserts a
986 predicate, we can take the intersection of the two ranges to
987 get better precision. */
988 if (value_ranges_intersect_p (var_vr, vr_p))
990 /* Use the larger of the two minimums. */
991 if (compare_values (vr_p->min, var_vr->min) == -1)
996 /* Use the smaller of the two maximums. */
997 if (compare_values (vr_p->max, var_vr->max) == 1)
1002 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
1006 /* The two ranges do not intersect, set the new range to
1007 VARYING, because we will not be able to do anything
1008 meaningful with it. */
1009 set_value_range_to_varying (vr_p);
1012 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
1013 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
1015 /* A range and an anti-range will cancel each other only if
1016 their ends are the same. For instance, in the example above,
1017 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1018 so VR_P should be set to VR_VARYING. */
1019 if (compare_values (var_vr->min, vr_p->min) == 0
1020 && compare_values (var_vr->max, vr_p->max) == 0)
1021 set_value_range_to_varying (vr_p);
1024 tree min, max, anti_min, anti_max, real_min, real_max;
1026 /* We want to compute the logical AND of the two ranges;
1027 there are three cases to consider.
1030 1. The VR_ANTI_RANGE range is completely within the
1031 VR_RANGE and the endpoints of the ranges are
1032 different. In that case the resulting range
1033 should be whichever range is more precise.
1034 Typically that will be the VR_RANGE.
1036 2. The VR_ANTI_RANGE is completely disjoint from
1037 the VR_RANGE. In this case the resulting range
1038 should be the VR_RANGE.
1040 3. There is some overlap between the VR_ANTI_RANGE
1043 3a. If the high limit of the VR_ANTI_RANGE resides
1044 within the VR_RANGE, then the result is a new
1045 VR_RANGE starting at the high limit of the
1046 the VR_ANTI_RANGE + 1 and extending to the
1047 high limit of the original VR_RANGE.
1049 3b. If the low limit of the VR_ANTI_RANGE resides
1050 within the VR_RANGE, then the result is a new
1051 VR_RANGE starting at the low limit of the original
1052 VR_RANGE and extending to the low limit of the
1053 VR_ANTI_RANGE - 1. */
1054 if (vr_p->type == VR_ANTI_RANGE)
1056 anti_min = vr_p->min;
1057 anti_max = vr_p->max;
1058 real_min = var_vr->min;
1059 real_max = var_vr->max;
1063 anti_min = var_vr->min;
1064 anti_max = var_vr->max;
1065 real_min = vr_p->min;
1066 real_max = vr_p->max;
1070 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1071 not including any endpoints. */
1072 if (compare_values (anti_max, real_max) == -1
1073 && compare_values (anti_min, real_min) == 1)
1075 set_value_range (vr_p, VR_RANGE, real_min,
1076 real_max, vr_p->equiv);
1078 /* Case 2, VR_ANTI_RANGE completely disjoint from
1080 else if (compare_values (anti_min, real_max) == 1
1081 || compare_values (anti_max, real_min) == -1)
1083 set_value_range (vr_p, VR_RANGE, real_min,
1084 real_max, vr_p->equiv);
1086 /* Case 3a, the anti-range extends into the low
1087 part of the real range. Thus creating a new
1088 low for the real range. */
1089 else if ((compare_values (anti_max, real_min) == 1
1090 || compare_values (anti_max, real_min) == 0)
1091 && compare_values (anti_max, real_max) == -1)
1093 min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min),
1095 build_int_cst (TREE_TYPE (var_vr->min), 1));
1097 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1099 /* Case 3b, the anti-range extends into the high
1100 part of the real range. Thus creating a new
1101 higher for the real range. */
1102 else if (compare_values (anti_min, real_min) == 1
1103 && (compare_values (anti_min, real_max) == -1
1104 || compare_values (anti_min, real_max) == 0))
1106 max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min),
1108 build_int_cst (TREE_TYPE (var_vr->min), 1));
1110 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1117 /* Extract range information from SSA name VAR and store it in VR. If
1118 VAR has an interesting range, use it. Otherwise, create the
1119 range [VAR, VAR] and return it. This is useful in situations where
1120 we may have conditionals testing values of VARYING names. For
1127 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1131 extract_range_from_ssa_name (value_range_t *vr, tree var)
1133 value_range_t *var_vr = get_value_range (var);
1135 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
1136 copy_value_range (vr, var_vr);
1138 set_value_range (vr, VR_RANGE, var, var, NULL);
1140 add_equivalence (vr->equiv, var);
1144 /* Wrapper around int_const_binop. If the operation overflows and we
1145 are not using wrapping arithmetic, then adjust the result to be
1146 -INF or +INF depending on CODE, VAL1 and VAL2. */
1149 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
1153 res = int_const_binop (code, val1, val2, 0);
1155 /* If we are not using wrapping arithmetic, operate symbolically
1156 on -INF and +INF. */
1157 if (TYPE_UNSIGNED (TREE_TYPE (val1))
1160 int checkz = compare_values (res, val1);
1161 bool overflow = false;
1163 /* Ensure that res = val1 [+*] val2 >= val1
1164 or that res = val1 - val2 <= val1. */
1165 if ((code == PLUS_EXPR
1166 && !(checkz == 1 || checkz == 0))
1167 || (code == MINUS_EXPR
1168 && !(checkz == 0 || checkz == -1)))
1172 /* Checking for multiplication overflow is done by dividing the
1173 output of the multiplication by the first input of the
1174 multiplication. If the result of that division operation is
1175 not equal to the second input of the multiplication, then the
1176 multiplication overflowed. */
1177 else if (code == MULT_EXPR && !integer_zerop (val1))
1179 tree tmp = int_const_binop (TRUNC_DIV_EXPR,
1180 TYPE_MAX_VALUE (TREE_TYPE (val1)),
1182 int check = compare_values (tmp, val2);
1190 res = copy_node (res);
1191 TREE_OVERFLOW (res) = 1;
1195 else if (TREE_OVERFLOW (res)
1196 && !TREE_OVERFLOW (val1)
1197 && !TREE_OVERFLOW (val2))
1199 /* If the operation overflowed but neither VAL1 nor VAL2 are
1200 overflown, return -INF or +INF depending on the operation
1201 and the combination of signs of the operands. */
1202 int sgn1 = tree_int_cst_sgn (val1);
1203 int sgn2 = tree_int_cst_sgn (val2);
1205 /* Notice that we only need to handle the restricted set of
1206 operations handled by extract_range_from_binary_expr.
1207 Among them, only multiplication, addition and subtraction
1208 can yield overflow without overflown operands because we
1209 are working with integral types only... except in the
1210 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1211 for division too. */
1213 /* For multiplication, the sign of the overflow is given
1214 by the comparison of the signs of the operands. */
1215 if ((code == MULT_EXPR && sgn1 == sgn2)
1216 /* For addition, the operands must be of the same sign
1217 to yield an overflow. Its sign is therefore that
1218 of one of the operands, for example the first. */
1219 || (code == PLUS_EXPR && sgn1 > 0)
1220 /* For subtraction, the operands must be of different
1221 signs to yield an overflow. Its sign is therefore
1222 that of the first operand or the opposite of that
1223 of the second operand. A first operand of 0 counts
1224 as positive here, for the corner case 0 - (-INF),
1225 which overflows, but must yield +INF. */
1226 || (code == MINUS_EXPR && sgn1 >= 0)
1227 /* For division, the only case is -INF / -1 = +INF. */
1228 || code == TRUNC_DIV_EXPR
1229 || code == FLOOR_DIV_EXPR
1230 || code == CEIL_DIV_EXPR
1231 || code == EXACT_DIV_EXPR
1232 || code == ROUND_DIV_EXPR)
1233 return TYPE_MAX_VALUE (TREE_TYPE (res));
1235 return TYPE_MIN_VALUE (TREE_TYPE (res));
1242 /* Extract range information from a binary expression EXPR based on
1243 the ranges of each of its operands and the expression code. */
1246 extract_range_from_binary_expr (value_range_t *vr, tree expr)
1248 enum tree_code code = TREE_CODE (expr);
1249 enum value_range_type type;
1250 tree op0, op1, min, max;
1252 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1253 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1255 /* Not all binary expressions can be applied to ranges in a
1256 meaningful way. Handle only arithmetic operations. */
1257 if (code != PLUS_EXPR
1258 && code != MINUS_EXPR
1259 && code != MULT_EXPR
1260 && code != TRUNC_DIV_EXPR
1261 && code != FLOOR_DIV_EXPR
1262 && code != CEIL_DIV_EXPR
1263 && code != EXACT_DIV_EXPR
1264 && code != ROUND_DIV_EXPR
1267 && code != BIT_AND_EXPR
1268 && code != TRUTH_ANDIF_EXPR
1269 && code != TRUTH_ORIF_EXPR
1270 && code != TRUTH_AND_EXPR
1271 && code != TRUTH_OR_EXPR)
1273 set_value_range_to_varying (vr);
1277 /* Get value ranges for each operand. For constant operands, create
1278 a new value range with the operand to simplify processing. */
1279 op0 = TREE_OPERAND (expr, 0);
1280 if (TREE_CODE (op0) == SSA_NAME)
1281 vr0 = *(get_value_range (op0));
1282 else if (is_gimple_min_invariant (op0))
1283 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1285 set_value_range_to_varying (&vr0);
1287 op1 = TREE_OPERAND (expr, 1);
1288 if (TREE_CODE (op1) == SSA_NAME)
1289 vr1 = *(get_value_range (op1));
1290 else if (is_gimple_min_invariant (op1))
1291 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1293 set_value_range_to_varying (&vr1);
1295 /* If either range is UNDEFINED, so is the result. */
1296 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1298 set_value_range_to_undefined (vr);
1302 /* The type of the resulting value range defaults to VR0.TYPE. */
1305 /* Refuse to operate on VARYING ranges, ranges of different kinds
1306 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1307 because we may be able to derive a useful range even if one of
1308 the operands is VR_VARYING or symbolic range. TODO, we may be
1309 able to derive anti-ranges in some cases. */
1310 if (code != BIT_AND_EXPR
1311 && code != TRUTH_AND_EXPR
1312 && code != TRUTH_OR_EXPR
1313 && (vr0.type == VR_VARYING
1314 || vr1.type == VR_VARYING
1315 || vr0.type != vr1.type
1316 || symbolic_range_p (&vr0)
1317 || symbolic_range_p (&vr1)))
1319 set_value_range_to_varying (vr);
1323 /* Now evaluate the expression to determine the new range. */
1324 if (POINTER_TYPE_P (TREE_TYPE (expr))
1325 || POINTER_TYPE_P (TREE_TYPE (op0))
1326 || POINTER_TYPE_P (TREE_TYPE (op1)))
1328 /* For pointer types, we are really only interested in asserting
1329 whether the expression evaluates to non-NULL. FIXME, we used
1330 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1331 ivopts is generating expressions with pointer multiplication
1333 if (code == PLUS_EXPR)
1335 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1336 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1337 else if (range_is_null (&vr0) && range_is_null (&vr1))
1338 set_value_range_to_null (vr, TREE_TYPE (expr));
1340 set_value_range_to_varying (vr);
1344 /* Subtracting from a pointer, may yield 0, so just drop the
1345 resulting range to varying. */
1346 set_value_range_to_varying (vr);
1352 /* For integer ranges, apply the operation to each end of the
1353 range and see what we end up with. */
1354 if (code == TRUTH_ANDIF_EXPR
1355 || code == TRUTH_ORIF_EXPR
1356 || code == TRUTH_AND_EXPR
1357 || code == TRUTH_OR_EXPR)
1359 /* If one of the operands is zero, we know that the whole
1360 expression evaluates zero. */
1361 if (code == TRUTH_AND_EXPR
1362 && ((vr0.type == VR_RANGE
1363 && integer_zerop (vr0.min)
1364 && integer_zerop (vr0.max))
1365 || (vr1.type == VR_RANGE
1366 && integer_zerop (vr1.min)
1367 && integer_zerop (vr1.max))))
1370 min = max = build_int_cst (TREE_TYPE (expr), 0);
1372 /* If one of the operands is one, we know that the whole
1373 expression evaluates one. */
1374 else if (code == TRUTH_OR_EXPR
1375 && ((vr0.type == VR_RANGE
1376 && integer_onep (vr0.min)
1377 && integer_onep (vr0.max))
1378 || (vr1.type == VR_RANGE
1379 && integer_onep (vr1.min)
1380 && integer_onep (vr1.max))))
1383 min = max = build_int_cst (TREE_TYPE (expr), 1);
1385 else if (vr0.type != VR_VARYING
1386 && vr1.type != VR_VARYING
1387 && vr0.type == vr1.type
1388 && !symbolic_range_p (&vr0)
1389 && !symbolic_range_p (&vr1))
1391 /* Boolean expressions cannot be folded with int_const_binop. */
1392 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1393 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1397 set_value_range_to_varying (vr);
1401 else if (code == PLUS_EXPR
1403 || code == MAX_EXPR)
1405 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1406 VR_VARYING. It would take more effort to compute a precise
1407 range for such a case. For example, if we have op0 == 1 and
1408 op1 == -1 with their ranges both being ~[0,0], we would have
1409 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1410 Note that we are guaranteed to have vr0.type == vr1.type at
1412 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1414 set_value_range_to_varying (vr);
1418 /* For operations that make the resulting range directly
1419 proportional to the original ranges, apply the operation to
1420 the same end of each range. */
1421 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1422 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1424 else if (code == MULT_EXPR
1425 || code == TRUNC_DIV_EXPR
1426 || code == FLOOR_DIV_EXPR
1427 || code == CEIL_DIV_EXPR
1428 || code == EXACT_DIV_EXPR
1429 || code == ROUND_DIV_EXPR)
1434 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1435 drop to VR_VARYING. It would take more effort to compute a
1436 precise range for such a case. For example, if we have
1437 op0 == 65536 and op1 == 65536 with their ranges both being
1438 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1439 we cannot claim that the product is in ~[0,0]. Note that we
1440 are guaranteed to have vr0.type == vr1.type at this
1442 if (code == MULT_EXPR
1443 && vr0.type == VR_ANTI_RANGE
1444 && (flag_wrapv || TYPE_UNSIGNED (TREE_TYPE (op0))))
1446 set_value_range_to_varying (vr);
1450 /* Multiplications and divisions are a bit tricky to handle,
1451 depending on the mix of signs we have in the two ranges, we
1452 need to operate on different values to get the minimum and
1453 maximum values for the new range. One approach is to figure
1454 out all the variations of range combinations and do the
1457 However, this involves several calls to compare_values and it
1458 is pretty convoluted. It's simpler to do the 4 operations
1459 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1460 MAX1) and then figure the smallest and largest values to form
1463 /* Divisions by zero result in a VARYING value. */
1464 if (code != MULT_EXPR
1465 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1467 set_value_range_to_varying (vr);
1471 /* Compute the 4 cross operations. */
1472 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1474 val[1] = (vr1.max != vr1.min)
1475 ? vrp_int_const_binop (code, vr0.min, vr1.max)
1478 val[2] = (vr0.max != vr0.min)
1479 ? vrp_int_const_binop (code, vr0.max, vr1.min)
1482 val[3] = (vr0.min != vr0.max && vr1.min != vr1.max)
1483 ? vrp_int_const_binop (code, vr0.max, vr1.max)
1486 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1490 for (i = 1; i < 4; i++)
1492 if (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
1493 || !is_gimple_min_invariant (max) || TREE_OVERFLOW (max))
1498 if (!is_gimple_min_invariant (val[i]) || TREE_OVERFLOW (val[i]))
1500 /* If we found an overflowed value, set MIN and MAX
1501 to it so that we set the resulting range to
1507 if (compare_values (val[i], min) == -1)
1510 if (compare_values (val[i], max) == 1)
1515 else if (code == MINUS_EXPR)
1517 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1518 VR_VARYING. It would take more effort to compute a precise
1519 range for such a case. For example, if we have op0 == 1 and
1520 op1 == 1 with their ranges both being ~[0,0], we would have
1521 op0 - op1 == 0, so we cannot claim that the difference is in
1522 ~[0,0]. Note that we are guaranteed to have
1523 vr0.type == vr1.type at this point. */
1524 if (vr0.type == VR_ANTI_RANGE)
1526 set_value_range_to_varying (vr);
1530 /* For MINUS_EXPR, apply the operation to the opposite ends of
1532 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1533 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1535 else if (code == BIT_AND_EXPR)
1537 if (vr0.type == VR_RANGE
1538 && vr0.min == vr0.max
1539 && tree_expr_nonnegative_p (vr0.max)
1540 && TREE_CODE (vr0.max) == INTEGER_CST)
1542 min = build_int_cst (TREE_TYPE (expr), 0);
1545 else if (vr1.type == VR_RANGE
1546 && vr1.min == vr1.max
1547 && tree_expr_nonnegative_p (vr1.max)
1548 && TREE_CODE (vr1.max) == INTEGER_CST)
1551 min = build_int_cst (TREE_TYPE (expr), 0);
1556 set_value_range_to_varying (vr);
1563 /* If either MIN or MAX overflowed, then set the resulting range to
1565 if (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
1566 || !is_gimple_min_invariant (max) || TREE_OVERFLOW (max))
1568 set_value_range_to_varying (vr);
1572 cmp = compare_values (min, max);
1573 if (cmp == -2 || cmp == 1)
1575 /* If the new range has its limits swapped around (MIN > MAX),
1576 then the operation caused one of them to wrap around, mark
1577 the new range VARYING. */
1578 set_value_range_to_varying (vr);
1581 set_value_range (vr, type, min, max, NULL);
1585 /* Extract range information from a unary expression EXPR based on
1586 the range of its operand and the expression code. */
1589 extract_range_from_unary_expr (value_range_t *vr, tree expr)
1591 enum tree_code code = TREE_CODE (expr);
1594 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1596 /* Refuse to operate on certain unary expressions for which we
1597 cannot easily determine a resulting range. */
1598 if (code == FIX_TRUNC_EXPR
1599 || code == FIX_CEIL_EXPR
1600 || code == FIX_FLOOR_EXPR
1601 || code == FIX_ROUND_EXPR
1602 || code == FLOAT_EXPR
1603 || code == BIT_NOT_EXPR
1604 || code == NON_LVALUE_EXPR
1605 || code == CONJ_EXPR)
1607 set_value_range_to_varying (vr);
1611 /* Get value ranges for the operand. For constant operands, create
1612 a new value range with the operand to simplify processing. */
1613 op0 = TREE_OPERAND (expr, 0);
1614 if (TREE_CODE (op0) == SSA_NAME)
1615 vr0 = *(get_value_range (op0));
1616 else if (is_gimple_min_invariant (op0))
1617 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1619 set_value_range_to_varying (&vr0);
1621 /* If VR0 is UNDEFINED, so is the result. */
1622 if (vr0.type == VR_UNDEFINED)
1624 set_value_range_to_undefined (vr);
1628 /* Refuse to operate on symbolic ranges, or if neither operand is
1629 a pointer or integral type. */
1630 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0))
1631 && !POINTER_TYPE_P (TREE_TYPE (op0)))
1632 || (vr0.type != VR_VARYING
1633 && symbolic_range_p (&vr0)))
1635 set_value_range_to_varying (vr);
1639 /* If the expression involves pointers, we are only interested in
1640 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1641 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
1643 if (range_is_nonnull (&vr0) || tree_expr_nonzero_p (expr))
1644 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1645 else if (range_is_null (&vr0))
1646 set_value_range_to_null (vr, TREE_TYPE (expr));
1648 set_value_range_to_varying (vr);
1653 /* Handle unary expressions on integer ranges. */
1654 if (code == NOP_EXPR || code == CONVERT_EXPR)
1656 tree inner_type = TREE_TYPE (op0);
1657 tree outer_type = TREE_TYPE (expr);
1659 /* If VR0 represents a simple range, then try to convert
1660 the min and max values for the range to the same type
1661 as OUTER_TYPE. If the results compare equal to VR0's
1662 min and max values and the new min is still less than
1663 or equal to the new max, then we can safely use the newly
1664 computed range for EXPR. This allows us to compute
1665 accurate ranges through many casts. */
1666 if (vr0.type == VR_RANGE
1667 || (vr0.type == VR_VARYING
1668 && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type)))
1670 tree new_min, new_max, orig_min, orig_max;
1672 /* Convert the input operand min/max to OUTER_TYPE. If
1673 the input has no range information, then use the min/max
1674 for the input's type. */
1675 if (vr0.type == VR_RANGE)
1682 orig_min = TYPE_MIN_VALUE (inner_type);
1683 orig_max = TYPE_MAX_VALUE (inner_type);
1686 new_min = fold_convert (outer_type, orig_min);
1687 new_max = fold_convert (outer_type, orig_max);
1689 /* Verify the new min/max values are gimple values and
1690 that they compare equal to the original input's
1692 if (is_gimple_val (new_min)
1693 && is_gimple_val (new_max)
1694 && tree_int_cst_equal (new_min, orig_min)
1695 && tree_int_cst_equal (new_max, orig_max)
1696 && compare_values (new_min, new_max) <= 0
1697 && compare_values (new_min, new_max) >= -1)
1699 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
1704 /* When converting types of different sizes, set the result to
1705 VARYING. Things like sign extensions and precision loss may
1706 change the range. For instance, if x_3 is of type 'long long
1707 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1708 is impossible to know at compile time whether y_5 will be
1710 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
1711 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
1713 set_value_range_to_varying (vr);
1718 /* Conversion of a VR_VARYING value to a wider type can result
1719 in a usable range. So wait until after we've handled conversions
1720 before dropping the result to VR_VARYING if we had a source
1721 operand that is VR_VARYING. */
1722 if (vr0.type == VR_VARYING)
1724 set_value_range_to_varying (vr);
1728 /* Apply the operation to each end of the range and see what we end
1730 if (code == NEGATE_EXPR
1731 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1733 /* NEGATE_EXPR flips the range around. We need to treat
1734 TYPE_MIN_VALUE specially dependent on wrapping, range type
1735 and if it was used as minimum or maximum value:
1736 -~[MIN, MIN] == ~[MIN, MIN]
1737 -[MIN, 0] == [0, MAX] for -fno-wrapv
1738 -[MIN, 0] == [0, MIN] for -fwrapv (will be set to varying later) */
1739 min = vr0.max == TYPE_MIN_VALUE (TREE_TYPE (expr))
1740 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1741 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1743 max = vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr))
1744 ? (vr0.type == VR_ANTI_RANGE || flag_wrapv
1745 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1746 : TYPE_MAX_VALUE (TREE_TYPE (expr)))
1747 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1750 else if (code == NEGATE_EXPR
1751 && TYPE_UNSIGNED (TREE_TYPE (expr)))
1753 if (!range_includes_zero_p (&vr0))
1755 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1756 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1760 if (range_is_null (&vr0))
1761 set_value_range_to_null (vr, TREE_TYPE (expr));
1763 set_value_range_to_varying (vr);
1767 else if (code == ABS_EXPR
1768 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1770 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1773 && ((vr0.type == VR_RANGE
1774 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1775 || (vr0.type == VR_ANTI_RANGE
1776 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
1777 && !range_includes_zero_p (&vr0))))
1779 set_value_range_to_varying (vr);
1783 /* ABS_EXPR may flip the range around, if the original range
1784 included negative values. */
1785 min = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1786 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1787 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1789 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1791 cmp = compare_values (min, max);
1793 /* If a VR_ANTI_RANGEs contains zero, then we have
1794 ~[-INF, min(MIN, MAX)]. */
1795 if (vr0.type == VR_ANTI_RANGE)
1797 if (range_includes_zero_p (&vr0))
1799 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
1801 /* Take the lower of the two values. */
1805 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1806 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1807 flag_wrapv is set and the original anti-range doesn't include
1808 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1809 min = (flag_wrapv && vr0.min != type_min_value
1810 ? int_const_binop (PLUS_EXPR,
1812 integer_one_node, 0)
1817 /* All else has failed, so create the range [0, INF], even for
1818 flag_wrapv since TYPE_MIN_VALUE is in the original
1820 vr0.type = VR_RANGE;
1821 min = build_int_cst (TREE_TYPE (expr), 0);
1822 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
1826 /* If the range contains zero then we know that the minimum value in the
1827 range will be zero. */
1828 else if (range_includes_zero_p (&vr0))
1832 min = build_int_cst (TREE_TYPE (expr), 0);
1836 /* If the range was reversed, swap MIN and MAX. */
1847 /* Otherwise, operate on each end of the range. */
1848 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1849 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1852 cmp = compare_values (min, max);
1853 if (cmp == -2 || cmp == 1)
1855 /* If the new range has its limits swapped around (MIN > MAX),
1856 then the operation caused one of them to wrap around, mark
1857 the new range VARYING. */
1858 set_value_range_to_varying (vr);
1861 set_value_range (vr, vr0.type, min, max, NULL);
1865 /* Extract range information from a comparison expression EXPR based
1866 on the range of its operand and the expression code. */
1869 extract_range_from_comparison (value_range_t *vr, tree expr)
1871 tree val = vrp_evaluate_conditional (expr, false);
1874 /* Since this expression was found on the RHS of an assignment,
1875 its type may be different from _Bool. Convert VAL to EXPR's
1877 val = fold_convert (TREE_TYPE (expr), val);
1878 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
1881 set_value_range_to_varying (vr);
1885 /* Try to compute a useful range out of expression EXPR and store it
1889 extract_range_from_expr (value_range_t *vr, tree expr)
1891 enum tree_code code = TREE_CODE (expr);
1893 if (code == ASSERT_EXPR)
1894 extract_range_from_assert (vr, expr);
1895 else if (code == SSA_NAME)
1896 extract_range_from_ssa_name (vr, expr);
1897 else if (TREE_CODE_CLASS (code) == tcc_binary
1898 || code == TRUTH_ANDIF_EXPR
1899 || code == TRUTH_ORIF_EXPR
1900 || code == TRUTH_AND_EXPR
1901 || code == TRUTH_OR_EXPR
1902 || code == TRUTH_XOR_EXPR)
1903 extract_range_from_binary_expr (vr, expr);
1904 else if (TREE_CODE_CLASS (code) == tcc_unary)
1905 extract_range_from_unary_expr (vr, expr);
1906 else if (TREE_CODE_CLASS (code) == tcc_comparison)
1907 extract_range_from_comparison (vr, expr);
1908 else if (is_gimple_min_invariant (expr))
1909 set_value_range (vr, VR_RANGE, expr, expr, NULL);
1911 set_value_range_to_varying (vr);
1913 /* If we got a varying range from the tests above, try a final
1914 time to derive a nonnegative or nonzero range. This time
1915 relying primarily on generic routines in fold in conjunction
1917 if (vr->type == VR_VARYING)
1919 if (INTEGRAL_TYPE_P (TREE_TYPE (expr))
1920 && vrp_expr_computes_nonnegative (expr))
1921 set_value_range_to_nonnegative (vr, TREE_TYPE (expr));
1922 else if (vrp_expr_computes_nonzero (expr))
1923 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1927 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1928 would be profitable to adjust VR using scalar evolution information
1929 for VAR. If so, update VR with the new limits. */
1932 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
1935 tree init, step, chrec, tmin, tmax, min, max, type;
1936 enum ev_direction dir;
1938 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1939 better opportunities than a regular range, but I'm not sure. */
1940 if (vr->type == VR_ANTI_RANGE)
1943 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
1944 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
1947 init = initial_condition_in_loop_num (chrec, loop->num);
1948 step = evolution_part_in_loop_num (chrec, loop->num);
1950 /* If STEP is symbolic, we can't know whether INIT will be the
1951 minimum or maximum value in the range. Also, unless INIT is
1952 a simple expression, compare_values and possibly other functions
1953 in tree-vrp won't be able to handle it. */
1954 if (step == NULL_TREE
1955 || !is_gimple_min_invariant (step)
1956 || !valid_value_p (init))
1959 dir = scev_direction (chrec);
1960 if (/* Do not adjust ranges if we do not know whether the iv increases
1961 or decreases, ... */
1962 dir == EV_DIR_UNKNOWN
1963 /* ... or if it may wrap. */
1964 || scev_probably_wraps_p (init, step, stmt,
1965 current_loops->parray[CHREC_VARIABLE (chrec)],
1969 type = TREE_TYPE (var);
1970 if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type))
1971 tmin = lower_bound_in_type (type, type);
1973 tmin = TYPE_MIN_VALUE (type);
1974 if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type))
1975 tmax = upper_bound_in_type (type, type);
1977 tmax = TYPE_MAX_VALUE (type);
1979 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
1984 /* For VARYING or UNDEFINED ranges, just about anything we get
1985 from scalar evolutions should be better. */
1987 if (dir == EV_DIR_DECREASES)
1992 /* If we would create an invalid range, then just assume we
1993 know absolutely nothing. This may be over-conservative,
1994 but it's clearly safe, and should happen only in unreachable
1995 parts of code, or for invalid programs. */
1996 if (compare_values (min, max) == 1)
1999 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2001 else if (vr->type == VR_RANGE)
2006 if (dir == EV_DIR_DECREASES)
2008 /* INIT is the maximum value. If INIT is lower than VR->MAX
2009 but no smaller than VR->MIN, set VR->MAX to INIT. */
2010 if (compare_values (init, max) == -1)
2014 /* If we just created an invalid range with the minimum
2015 greater than the maximum, we fail conservatively.
2016 This should happen only in unreachable
2017 parts of code, or for invalid programs. */
2018 if (compare_values (min, max) == 1)
2024 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2025 if (compare_values (init, min) == 1)
2029 /* Again, avoid creating invalid range by failing. */
2030 if (compare_values (min, max) == 1)
2035 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2040 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2042 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2043 all the values in the ranges.
2045 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2047 - Return NULL_TREE if it is not always possible to determine the
2048 value of the comparison. */
2052 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1)
2054 /* VARYING or UNDEFINED ranges cannot be compared. */
2055 if (vr0->type == VR_VARYING
2056 || vr0->type == VR_UNDEFINED
2057 || vr1->type == VR_VARYING
2058 || vr1->type == VR_UNDEFINED)
2061 /* Anti-ranges need to be handled separately. */
2062 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
2064 /* If both are anti-ranges, then we cannot compute any
2066 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
2069 /* These comparisons are never statically computable. */
2076 /* Equality can be computed only between a range and an
2077 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2078 if (vr0->type == VR_RANGE)
2080 /* To simplify processing, make VR0 the anti-range. */
2081 value_range_t *tmp = vr0;
2086 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
2088 if (compare_values (vr0->min, vr1->min) == 0
2089 && compare_values (vr0->max, vr1->max) == 0)
2090 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2095 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2096 operands around and change the comparison code. */
2097 if (comp == GT_EXPR || comp == GE_EXPR)
2100 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
2106 if (comp == EQ_EXPR)
2108 /* Equality may only be computed if both ranges represent
2109 exactly one value. */
2110 if (compare_values (vr0->min, vr0->max) == 0
2111 && compare_values (vr1->min, vr1->max) == 0)
2113 int cmp_min = compare_values (vr0->min, vr1->min);
2114 int cmp_max = compare_values (vr0->max, vr1->max);
2115 if (cmp_min == 0 && cmp_max == 0)
2116 return boolean_true_node;
2117 else if (cmp_min != -2 && cmp_max != -2)
2118 return boolean_false_node;
2120 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2121 else if (compare_values (vr0->min, vr1->max) == 1
2122 || compare_values (vr1->min, vr0->max) == 1)
2123 return boolean_false_node;
2127 else if (comp == NE_EXPR)
2131 /* If VR0 is completely to the left or completely to the right
2132 of VR1, they are always different. Notice that we need to
2133 make sure that both comparisons yield similar results to
2134 avoid comparing values that cannot be compared at
2136 cmp1 = compare_values (vr0->max, vr1->min);
2137 cmp2 = compare_values (vr0->min, vr1->max);
2138 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
2139 return boolean_true_node;
2141 /* If VR0 and VR1 represent a single value and are identical,
2143 else if (compare_values (vr0->min, vr0->max) == 0
2144 && compare_values (vr1->min, vr1->max) == 0
2145 && compare_values (vr0->min, vr1->min) == 0
2146 && compare_values (vr0->max, vr1->max) == 0)
2147 return boolean_false_node;
2149 /* Otherwise, they may or may not be different. */
2153 else if (comp == LT_EXPR || comp == LE_EXPR)
2157 /* If VR0 is to the left of VR1, return true. */
2158 tst = compare_values (vr0->max, vr1->min);
2159 if ((comp == LT_EXPR && tst == -1)
2160 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2161 return boolean_true_node;
2163 /* If VR0 is to the right of VR1, return false. */
2164 tst = compare_values (vr0->min, vr1->max);
2165 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2166 || (comp == LE_EXPR && tst == 1))
2167 return boolean_false_node;
2169 /* Otherwise, we don't know. */
2177 /* Given a value range VR, a value VAL and a comparison code COMP, return
2178 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2179 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2180 always returns false. Return NULL_TREE if it is not always
2181 possible to determine the value of the comparison. */
2184 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val)
2186 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2189 /* Anti-ranges need to be handled separately. */
2190 if (vr->type == VR_ANTI_RANGE)
2192 /* For anti-ranges, the only predicates that we can compute at
2193 compile time are equality and inequality. */
2200 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2201 if (value_inside_range (val, vr) == 1)
2202 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2207 if (comp == EQ_EXPR)
2209 /* EQ_EXPR may only be computed if VR represents exactly
2211 if (compare_values (vr->min, vr->max) == 0)
2213 int cmp = compare_values (vr->min, val);
2215 return boolean_true_node;
2216 else if (cmp == -1 || cmp == 1 || cmp == 2)
2217 return boolean_false_node;
2219 else if (compare_values (val, vr->min) == -1
2220 || compare_values (vr->max, val) == -1)
2221 return boolean_false_node;
2225 else if (comp == NE_EXPR)
2227 /* If VAL is not inside VR, then they are always different. */
2228 if (compare_values (vr->max, val) == -1
2229 || compare_values (vr->min, val) == 1)
2230 return boolean_true_node;
2232 /* If VR represents exactly one value equal to VAL, then return
2234 if (compare_values (vr->min, vr->max) == 0
2235 && compare_values (vr->min, val) == 0)
2236 return boolean_false_node;
2238 /* Otherwise, they may or may not be different. */
2241 else if (comp == LT_EXPR || comp == LE_EXPR)
2245 /* If VR is to the left of VAL, return true. */
2246 tst = compare_values (vr->max, val);
2247 if ((comp == LT_EXPR && tst == -1)
2248 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2249 return boolean_true_node;
2251 /* If VR is to the right of VAL, return false. */
2252 tst = compare_values (vr->min, val);
2253 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2254 || (comp == LE_EXPR && tst == 1))
2255 return boolean_false_node;
2257 /* Otherwise, we don't know. */
2260 else if (comp == GT_EXPR || comp == GE_EXPR)
2264 /* If VR is to the right of VAL, return true. */
2265 tst = compare_values (vr->min, val);
2266 if ((comp == GT_EXPR && tst == 1)
2267 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
2268 return boolean_true_node;
2270 /* If VR is to the left of VAL, return false. */
2271 tst = compare_values (vr->max, val);
2272 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
2273 || (comp == GE_EXPR && tst == -1))
2274 return boolean_false_node;
2276 /* Otherwise, we don't know. */
2284 /* Debugging dumps. */
2286 void dump_value_range (FILE *, value_range_t *);
2287 void debug_value_range (value_range_t *);
2288 void dump_all_value_ranges (FILE *);
2289 void debug_all_value_ranges (void);
2290 void dump_vr_equiv (FILE *, bitmap);
2291 void debug_vr_equiv (bitmap);
2294 /* Dump value range VR to FILE. */
2297 dump_value_range (FILE *file, value_range_t *vr)
2300 fprintf (file, "[]");
2301 else if (vr->type == VR_UNDEFINED)
2302 fprintf (file, "UNDEFINED");
2303 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
2305 tree type = TREE_TYPE (vr->min);
2307 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
2309 if (INTEGRAL_TYPE_P (type)
2310 && !TYPE_UNSIGNED (type)
2311 && vr->min == TYPE_MIN_VALUE (type))
2312 fprintf (file, "-INF");
2314 print_generic_expr (file, vr->min, 0);
2316 fprintf (file, ", ");
2318 if (INTEGRAL_TYPE_P (type)
2319 && vr->max == TYPE_MAX_VALUE (type))
2320 fprintf (file, "+INF");
2322 print_generic_expr (file, vr->max, 0);
2324 fprintf (file, "]");
2331 fprintf (file, " EQUIVALENCES: { ");
2333 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
2335 print_generic_expr (file, ssa_name (i), 0);
2336 fprintf (file, " ");
2340 fprintf (file, "} (%u elements)", c);
2343 else if (vr->type == VR_VARYING)
2344 fprintf (file, "VARYING");
2346 fprintf (file, "INVALID RANGE");
2350 /* Dump value range VR to stderr. */
2353 debug_value_range (value_range_t *vr)
2355 dump_value_range (stderr, vr);
2356 fprintf (stderr, "\n");
2360 /* Dump value ranges of all SSA_NAMEs to FILE. */
2363 dump_all_value_ranges (FILE *file)
2367 for (i = 0; i < num_ssa_names; i++)
2371 print_generic_expr (file, ssa_name (i), 0);
2372 fprintf (file, ": ");
2373 dump_value_range (file, vr_value[i]);
2374 fprintf (file, "\n");
2378 fprintf (file, "\n");
2382 /* Dump all value ranges to stderr. */
2385 debug_all_value_ranges (void)
2387 dump_all_value_ranges (stderr);
2391 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
2392 create a new SSA name N and return the assertion assignment
2393 'V = ASSERT_EXPR <V, V OP W>'. */
2396 build_assert_expr_for (tree cond, tree v)
2400 gcc_assert (TREE_CODE (v) == SSA_NAME);
2401 n = duplicate_ssa_name (v, NULL_TREE);
2403 if (COMPARISON_CLASS_P (cond))
2405 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
2406 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, a);
2408 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
2410 /* Given !V, build the assignment N = false. */
2411 tree op0 = TREE_OPERAND (cond, 0);
2412 gcc_assert (op0 == v);
2413 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_false_node);
2415 else if (TREE_CODE (cond) == SSA_NAME)
2417 /* Given V, build the assignment N = true. */
2418 gcc_assert (v == cond);
2419 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_true_node);
2424 SSA_NAME_DEF_STMT (n) = assertion;
2426 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
2427 operand of the ASSERT_EXPR. Register the new name and the old one
2428 in the replacement table so that we can fix the SSA web after
2429 adding all the ASSERT_EXPRs. */
2430 register_new_name_mapping (n, v);
2436 /* Return false if EXPR is a predicate expression involving floating
2440 fp_predicate (tree expr)
2442 return (COMPARISON_CLASS_P (expr)
2443 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
2447 /* If the range of values taken by OP can be inferred after STMT executes,
2448 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2449 describes the inferred range. Return true if a range could be
2453 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
2456 *comp_code_p = ERROR_MARK;
2458 /* Do not attempt to infer anything in names that flow through
2460 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
2463 /* Similarly, don't infer anything from statements that may throw
2465 if (tree_could_throw_p (stmt))
2468 /* If STMT is the last statement of a basic block with no
2469 successors, there is no point inferring anything about any of its
2470 operands. We would not be able to find a proper insertion point
2471 for the assertion, anyway. */
2472 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
2475 /* We can only assume that a pointer dereference will yield
2476 non-NULL if -fdelete-null-pointer-checks is enabled. */
2477 if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op)))
2480 unsigned num_uses, num_derefs;
2482 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
2485 *val_p = build_int_cst (TREE_TYPE (op), 0);
2486 *comp_code_p = NE_EXPR;
2495 void dump_asserts_for (FILE *, tree);
2496 void debug_asserts_for (tree);
2497 void dump_all_asserts (FILE *);
2498 void debug_all_asserts (void);
2500 /* Dump all the registered assertions for NAME to FILE. */
2503 dump_asserts_for (FILE *file, tree name)
2507 fprintf (file, "Assertions to be inserted for ");
2508 print_generic_expr (file, name, 0);
2509 fprintf (file, "\n");
2511 loc = asserts_for[SSA_NAME_VERSION (name)];
2514 fprintf (file, "\t");
2515 print_generic_expr (file, bsi_stmt (loc->si), 0);
2516 fprintf (file, "\n\tBB #%d", loc->bb->index);
2519 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
2520 loc->e->dest->index);
2521 dump_edge_info (file, loc->e, 0);
2523 fprintf (file, "\n\tPREDICATE: ");
2524 print_generic_expr (file, name, 0);
2525 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
2526 print_generic_expr (file, loc->val, 0);
2527 fprintf (file, "\n\n");
2531 fprintf (file, "\n");
2535 /* Dump all the registered assertions for NAME to stderr. */
2538 debug_asserts_for (tree name)
2540 dump_asserts_for (stderr, name);
2544 /* Dump all the registered assertions for all the names to FILE. */
2547 dump_all_asserts (FILE *file)
2552 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
2553 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2554 dump_asserts_for (file, ssa_name (i));
2555 fprintf (file, "\n");
2559 /* Dump all the registered assertions for all the names to stderr. */
2562 debug_all_asserts (void)
2564 dump_all_asserts (stderr);
2568 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2569 'NAME COMP_CODE VAL' at a location that dominates block BB or
2570 E->DEST, then register this location as a possible insertion point
2571 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2573 BB, E and SI provide the exact insertion point for the new
2574 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2575 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2576 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2577 must not be NULL. */
2580 register_new_assert_for (tree name,
2581 enum tree_code comp_code,
2585 block_stmt_iterator si)
2587 assert_locus_t n, loc, last_loc;
2589 basic_block dest_bb;
2591 #if defined ENABLE_CHECKING
2592 gcc_assert (bb == NULL || e == NULL);
2595 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
2596 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
2599 /* The new assertion A will be inserted at BB or E. We need to
2600 determine if the new location is dominated by a previously
2601 registered location for A. If we are doing an edge insertion,
2602 assume that A will be inserted at E->DEST. Note that this is not
2605 If E is a critical edge, it will be split. But even if E is
2606 split, the new block will dominate the same set of blocks that
2609 The reverse, however, is not true, blocks dominated by E->DEST
2610 will not be dominated by the new block created to split E. So,
2611 if the insertion location is on a critical edge, we will not use
2612 the new location to move another assertion previously registered
2613 at a block dominated by E->DEST. */
2614 dest_bb = (bb) ? bb : e->dest;
2616 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2617 VAL at a block dominating DEST_BB, then we don't need to insert a new
2618 one. Similarly, if the same assertion already exists at a block
2619 dominated by DEST_BB and the new location is not on a critical
2620 edge, then update the existing location for the assertion (i.e.,
2621 move the assertion up in the dominance tree).
2623 Note, this is implemented as a simple linked list because there
2624 should not be more than a handful of assertions registered per
2625 name. If this becomes a performance problem, a table hashed by
2626 COMP_CODE and VAL could be implemented. */
2627 loc = asserts_for[SSA_NAME_VERSION (name)];
2632 if (loc->comp_code == comp_code
2634 || operand_equal_p (loc->val, val, 0)))
2636 /* If the assertion NAME COMP_CODE VAL has already been
2637 registered at a basic block that dominates DEST_BB, then
2638 we don't need to insert the same assertion again. Note
2639 that we don't check strict dominance here to avoid
2640 replicating the same assertion inside the same basic
2641 block more than once (e.g., when a pointer is
2642 dereferenced several times inside a block).
2644 An exception to this rule are edge insertions. If the
2645 new assertion is to be inserted on edge E, then it will
2646 dominate all the other insertions that we may want to
2647 insert in DEST_BB. So, if we are doing an edge
2648 insertion, don't do this dominance check. */
2650 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
2653 /* Otherwise, if E is not a critical edge and DEST_BB
2654 dominates the existing location for the assertion, move
2655 the assertion up in the dominance tree by updating its
2656 location information. */
2657 if ((e == NULL || !EDGE_CRITICAL_P (e))
2658 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
2667 /* Update the last node of the list and move to the next one. */
2672 /* If we didn't find an assertion already registered for
2673 NAME COMP_CODE VAL, add a new one at the end of the list of
2674 assertions associated with NAME. */
2675 n = XNEW (struct assert_locus_d);
2679 n->comp_code = comp_code;
2686 asserts_for[SSA_NAME_VERSION (name)] = n;
2688 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
2691 /* COND is a predicate which uses NAME. Extract a suitable test code
2692 and value and store them into *CODE_P and *VAL_P so the predicate
2693 is normalized to NAME *CODE_P *VAL_P.
2695 If no extraction was possible, return FALSE, otherwise return TRUE.
2697 If INVERT is true, then we invert the result stored into *CODE_P. */
2700 extract_code_and_val_from_cond (tree name, tree cond, bool invert,
2701 enum tree_code *code_p, tree *val_p)
2703 enum tree_code comp_code;
2706 /* Predicates may be a single SSA name or NAME OP VAL. */
2709 /* If the predicate is a name, it must be NAME, in which
2710 case we create the predicate NAME == true or
2711 NAME == false accordingly. */
2712 comp_code = EQ_EXPR;
2713 val = invert ? boolean_false_node : boolean_true_node;
2717 /* Otherwise, we have a comparison of the form NAME COMP VAL
2718 or VAL COMP NAME. */
2719 if (name == TREE_OPERAND (cond, 1))
2721 /* If the predicate is of the form VAL COMP NAME, flip
2722 COMP around because we need to register NAME as the
2723 first operand in the predicate. */
2724 comp_code = swap_tree_comparison (TREE_CODE (cond));
2725 val = TREE_OPERAND (cond, 0);
2729 /* The comparison is of the form NAME COMP VAL, so the
2730 comparison code remains unchanged. */
2731 comp_code = TREE_CODE (cond);
2732 val = TREE_OPERAND (cond, 1);
2735 /* Invert the comparison code as necessary. */
2737 comp_code = invert_tree_comparison (comp_code, 0);
2739 /* VRP does not handle float types. */
2740 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)))
2743 /* Do not register always-false predicates.
2744 FIXME: this works around a limitation in fold() when dealing with
2745 enumerations. Given 'enum { N1, N2 } x;', fold will not
2746 fold 'if (x > N2)' to 'if (0)'. */
2747 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
2748 && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2750 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
2751 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
2753 if (comp_code == GT_EXPR
2755 || compare_values (val, max) == 0))
2758 if (comp_code == LT_EXPR
2760 || compare_values (val, min) == 0))
2764 *code_p = comp_code;
2769 /* OP is an operand of a truth value expression which is known to have
2770 a particular value. Register any asserts for OP and for any
2771 operands in OP's defining statement.
2773 If CODE is EQ_EXPR, then we want to register OP is zero (false),
2774 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
2777 register_edge_assert_for_1 (tree op, enum tree_code code,
2778 edge e, block_stmt_iterator bsi)
2780 bool invert, retval = false;
2781 tree op_def, rhs, val;
2783 /* We only care about SSA_NAMEs. */
2784 if (TREE_CODE (op) != SSA_NAME)
2787 /* We know that OP will have a zero or nonzero value. If OP is used
2788 more than once go ahead and register an assert for OP.
2790 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
2791 it will always be set for OP (because OP is used in a COND_EXPR in
2793 if (!has_single_use (op))
2795 val = build_int_cst (TREE_TYPE (op), 0);
2796 register_new_assert_for (op, code, val, NULL, e, bsi);
2800 /* Now look at how OP is set. If it's set from a comparison,
2801 a truth operation or some bit operations, then we may be able
2802 to register information about the operands of that assignment. */
2803 op_def = SSA_NAME_DEF_STMT (op);
2804 if (TREE_CODE (op_def) != MODIFY_EXPR)
2807 invert = (code == EQ_EXPR ? true : false);
2808 rhs = TREE_OPERAND (op_def, 1);
2810 if (COMPARISON_CLASS_P (rhs))
2812 tree op0 = TREE_OPERAND (rhs, 0);
2813 tree op1 = TREE_OPERAND (rhs, 1);
2815 /* Conditionally register an assert for each SSA_NAME in the
2817 if (TREE_CODE (op0) == SSA_NAME
2818 && !has_single_use (op0)
2819 && extract_code_and_val_from_cond (op0, rhs,
2820 invert, &code, &val))
2822 register_new_assert_for (op0, code, val, NULL, e, bsi);
2826 /* Similarly for the second operand of the comparison. */
2827 if (TREE_CODE (op1) == SSA_NAME
2828 && !has_single_use (op1)
2829 && extract_code_and_val_from_cond (op1, rhs,
2830 invert, &code, &val))
2832 register_new_assert_for (op1, code, val, NULL, e, bsi);
2836 else if ((code == NE_EXPR
2837 && (TREE_CODE (rhs) == TRUTH_AND_EXPR
2838 || TREE_CODE (rhs) == BIT_AND_EXPR))
2840 && (TREE_CODE (rhs) == TRUTH_OR_EXPR
2841 || TREE_CODE (rhs) == BIT_IOR_EXPR)))
2843 /* Recurse on each operand. */
2844 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
2846 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 1),
2849 else if (TREE_CODE (rhs) == TRUTH_NOT_EXPR)
2852 /* Recurse, flipping the tense of INVERT. */
2853 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
2856 else if (TREE_CODE (rhs) == SSA_NAME)
2858 /* Recurse through the copy, the tense of INVERT remains
2860 retval |= register_edge_assert_for_1 (rhs, code, e, bsi);
2862 else if (TREE_CODE (rhs) == NOP_EXPR
2863 || TREE_CODE (rhs) == CONVERT_EXPR
2864 || TREE_CODE (rhs) == VIEW_CONVERT_EXPR
2865 || TREE_CODE (rhs) == NON_LVALUE_EXPR)
2867 /* Recurse through the type conversion, the tense of INVERT
2868 remains unchanged. */
2869 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
2876 /* Try to register an edge assertion for SSA name NAME on edge E for
2877 the condition COND contributing to the conditional jump pointed to by SI.
2878 Return true if an assertion for NAME could be registered. */
2881 register_edge_assert_for (tree name, edge e, block_stmt_iterator si, tree cond)
2884 enum tree_code comp_code;
2885 bool retval = false;
2886 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
2888 /* Do not attempt to infer anything in names that flow through
2890 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
2893 if (!extract_code_and_val_from_cond (name, cond, is_else_edge,
2897 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
2898 reachable from E. */
2899 if (TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
2901 register_new_assert_for (name, comp_code, val, NULL, e, si);
2905 /* If COND is effectively an equality test of an SSA_NAME against
2906 the value zero or one, then we may be able to assert values
2907 for SSA_NAMEs which flow into COND. */
2909 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
2910 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
2911 have non-zero value. */
2912 if (((comp_code == EQ_EXPR && integer_onep (val))
2913 || (comp_code == NE_EXPR && integer_zerop (val))))
2915 tree def_stmt = SSA_NAME_DEF_STMT (name);
2917 if (TREE_CODE (def_stmt) == MODIFY_EXPR
2918 && (TREE_CODE (TREE_OPERAND (def_stmt, 1)) == TRUTH_AND_EXPR
2919 || TREE_CODE (TREE_OPERAND (def_stmt, 1)) == BIT_AND_EXPR))
2921 tree op0 = TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 0);
2922 tree op1 = TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 1);
2923 retval |= register_edge_assert_for_1 (op0, NE_EXPR, e, si);
2924 retval |= register_edge_assert_for_1 (op1, NE_EXPR, e, si);
2928 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
2929 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
2931 if (((comp_code == EQ_EXPR && integer_zerop (val))
2932 || (comp_code == NE_EXPR && integer_onep (val))))
2934 tree def_stmt = SSA_NAME_DEF_STMT (name);
2936 if (TREE_CODE (def_stmt) == MODIFY_EXPR
2937 && (TREE_CODE (TREE_OPERAND (def_stmt, 1)) == TRUTH_OR_EXPR
2938 || TREE_CODE (TREE_OPERAND (def_stmt, 1)) == BIT_IOR_EXPR))
2940 tree op0 = TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 0);
2941 tree op1 = TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 1);
2942 retval |= register_edge_assert_for_1 (op0, EQ_EXPR, e, si);
2943 retval |= register_edge_assert_for_1 (op1, EQ_EXPR, e, si);
2951 static bool find_assert_locations (basic_block bb);
2953 /* Determine whether the outgoing edges of BB should receive an
2954 ASSERT_EXPR for each of the operands of BB's LAST statement.
2955 The last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2957 If any of the sub-graphs rooted at BB have an interesting use of
2958 the predicate operands, an assert location node is added to the
2959 list of assertions for the corresponding operands. */
2962 find_conditional_asserts (basic_block bb, tree last)
2965 block_stmt_iterator bsi;
2971 need_assert = false;
2972 bsi = bsi_for_stmt (last);
2974 /* Look for uses of the operands in each of the sub-graphs
2975 rooted at BB. We need to check each of the outgoing edges
2976 separately, so that we know what kind of ASSERT_EXPR to
2978 FOR_EACH_EDGE (e, ei, bb->succs)
2983 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
2984 Otherwise, when we finish traversing each of the sub-graphs, we
2985 won't know whether the variables were found in the sub-graphs or
2986 if they had been found in a block upstream from BB.
2988 This is actually a bad idea is some cases, particularly jump
2989 threading. Consider a CFG like the following:
2999 Assume that one or more operands in the conditional at the
3000 end of block 0 are used in a conditional in block 2, but not
3001 anywhere in block 1. In this case we will not insert any
3002 assert statements in block 1, which may cause us to miss
3003 opportunities to optimize, particularly for jump threading. */
3004 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3005 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3007 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3008 to determine if any of the operands in the conditional
3009 predicate are used. */
3011 need_assert |= find_assert_locations (e->dest);
3013 /* Register the necessary assertions for each operand in the
3014 conditional predicate. */
3015 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3016 need_assert |= register_edge_assert_for (op, e, bsi,
3017 COND_EXPR_COND (last));
3020 /* Finally, indicate that we have found the operands in the
3022 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3023 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3029 /* Traverse all the statements in block BB looking for statements that
3030 may generate useful assertions for the SSA names in their operand.
3031 If a statement produces a useful assertion A for name N_i, then the
3032 list of assertions already generated for N_i is scanned to
3033 determine if A is actually needed.
3035 If N_i already had the assertion A at a location dominating the
3036 current location, then nothing needs to be done. Otherwise, the
3037 new location for A is recorded instead.
3039 1- For every statement S in BB, all the variables used by S are
3040 added to bitmap FOUND_IN_SUBGRAPH.
3042 2- If statement S uses an operand N in a way that exposes a known
3043 value range for N, then if N was not already generated by an
3044 ASSERT_EXPR, create a new assert location for N. For instance,
3045 if N is a pointer and the statement dereferences it, we can
3046 assume that N is not NULL.
3048 3- COND_EXPRs are a special case of #2. We can derive range
3049 information from the predicate but need to insert different
3050 ASSERT_EXPRs for each of the sub-graphs rooted at the
3051 conditional block. If the last statement of BB is a conditional
3052 expression of the form 'X op Y', then
3054 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
3056 b) If the conditional is the only entry point to the sub-graph
3057 corresponding to the THEN_CLAUSE, recurse into it. On
3058 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
3059 an ASSERT_EXPR is added for the corresponding variable.
3061 c) Repeat step (b) on the ELSE_CLAUSE.
3063 d) Mark X and Y in FOUND_IN_SUBGRAPH.
3072 In this case, an assertion on the THEN clause is useful to
3073 determine that 'a' is always 9 on that edge. However, an assertion
3074 on the ELSE clause would be unnecessary.
3076 4- If BB does not end in a conditional expression, then we recurse
3077 into BB's dominator children.
3079 At the end of the recursive traversal, every SSA name will have a
3080 list of locations where ASSERT_EXPRs should be added. When a new
3081 location for name N is found, it is registered by calling
3082 register_new_assert_for. That function keeps track of all the
3083 registered assertions to prevent adding unnecessary assertions.
3084 For instance, if a pointer P_4 is dereferenced more than once in a
3085 dominator tree, only the location dominating all the dereference of
3086 P_4 will receive an ASSERT_EXPR.
3088 If this function returns true, then it means that there are names
3089 for which we need to generate ASSERT_EXPRs. Those assertions are
3090 inserted by process_assert_insertions.
3092 TODO. Handle SWITCH_EXPR. */
3095 find_assert_locations (basic_block bb)
3097 block_stmt_iterator si;
3102 if (TEST_BIT (blocks_visited, bb->index))
3105 SET_BIT (blocks_visited, bb->index);
3107 need_assert = false;
3109 /* Traverse all PHI nodes in BB marking used operands. */
3110 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3112 use_operand_p arg_p;
3115 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
3117 tree arg = USE_FROM_PTR (arg_p);
3118 if (TREE_CODE (arg) == SSA_NAME)
3120 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
3121 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
3126 /* Traverse all the statements in BB marking used names and looking
3127 for statements that may infer assertions for their used operands. */
3129 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3134 stmt = bsi_stmt (si);
3136 /* See if we can derive an assertion for any of STMT's operands. */
3137 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
3140 enum tree_code comp_code;
3142 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
3143 the sub-graph of a conditional block, when we return from
3144 this recursive walk, our parent will use the
3145 FOUND_IN_SUBGRAPH bitset to determine if one of the
3146 operands it was looking for was present in the sub-graph. */
3147 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3149 /* If OP is used in such a way that we can infer a value
3150 range for it, and we don't find a previous assertion for
3151 it, create a new assertion location node for OP. */
3152 if (infer_value_range (stmt, op, &comp_code, &value))
3154 /* If we are able to infer a nonzero value range for OP,
3155 then walk backwards through the use-def chain to see if OP
3156 was set via a typecast.
3158 If so, then we can also infer a nonzero value range
3159 for the operand of the NOP_EXPR. */
3160 if (comp_code == NE_EXPR && integer_zerop (value))
3163 tree def_stmt = SSA_NAME_DEF_STMT (t);
3165 while (TREE_CODE (def_stmt) == MODIFY_EXPR
3166 && TREE_CODE (TREE_OPERAND (def_stmt, 1)) == NOP_EXPR
3167 && TREE_CODE (TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 0)) == SSA_NAME
3168 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 0))))
3170 t = TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 0);
3171 def_stmt = SSA_NAME_DEF_STMT (t);
3173 /* Note we want to register the assert for the
3174 operand of the NOP_EXPR after SI, not after the
3176 if (! has_single_use (t))
3178 register_new_assert_for (t, comp_code, value,
3185 /* If OP is used only once, namely in this STMT, don't
3186 bother creating an ASSERT_EXPR for it. Such an
3187 ASSERT_EXPR would do nothing but increase compile time. */
3188 if (!has_single_use (op))
3190 register_new_assert_for (op, comp_code, value, bb, NULL, si);
3196 /* Remember the last statement of the block. */
3200 /* If BB's last statement is a conditional expression
3201 involving integer operands, recurse into each of the sub-graphs
3202 rooted at BB to determine if we need to add ASSERT_EXPRs. */
3204 && TREE_CODE (last) == COND_EXPR
3205 && !fp_predicate (COND_EXPR_COND (last))
3206 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
3207 need_assert |= find_conditional_asserts (bb, last);
3209 /* Recurse into the dominator children of BB. */
3210 for (son = first_dom_son (CDI_DOMINATORS, bb);
3212 son = next_dom_son (CDI_DOMINATORS, son))
3213 need_assert |= find_assert_locations (son);
3219 /* Create an ASSERT_EXPR for NAME and insert it in the location
3220 indicated by LOC. Return true if we made any edge insertions. */
3223 process_assert_insertions_for (tree name, assert_locus_t loc)
3225 /* Build the comparison expression NAME_i COMP_CODE VAL. */
3226 tree stmt, cond, assert_expr;
3230 cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
3231 assert_expr = build_assert_expr_for (cond, name);
3235 /* We have been asked to insert the assertion on an edge. This
3236 is used only by COND_EXPR and SWITCH_EXPR assertions. */
3237 #if defined ENABLE_CHECKING
3238 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
3239 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
3242 bsi_insert_on_edge (loc->e, assert_expr);
3246 /* Otherwise, we can insert right after LOC->SI iff the
3247 statement must not be the last statement in the block. */
3248 stmt = bsi_stmt (loc->si);
3249 if (!stmt_ends_bb_p (stmt))
3251 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
3255 /* If STMT must be the last statement in BB, we can only insert new
3256 assertions on the non-abnormal edge out of BB. Note that since
3257 STMT is not control flow, there may only be one non-abnormal edge
3259 FOR_EACH_EDGE (e, ei, loc->bb->succs)
3260 if (!(e->flags & EDGE_ABNORMAL))
3262 bsi_insert_on_edge (e, assert_expr);
3270 /* Process all the insertions registered for every name N_i registered
3271 in NEED_ASSERT_FOR. The list of assertions to be inserted are
3272 found in ASSERTS_FOR[i]. */
3275 process_assert_insertions (void)
3279 bool update_edges_p = false;
3280 int num_asserts = 0;
3282 if (dump_file && (dump_flags & TDF_DETAILS))
3283 dump_all_asserts (dump_file);
3285 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3287 assert_locus_t loc = asserts_for[i];
3292 assert_locus_t next = loc->next;
3293 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
3301 bsi_commit_edge_inserts ();
3303 if (dump_file && (dump_flags & TDF_STATS))
3304 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
3309 /* Traverse the flowgraph looking for conditional jumps to insert range
3310 expressions. These range expressions are meant to provide information
3311 to optimizations that need to reason in terms of value ranges. They
3312 will not be expanded into RTL. For instance, given:
3321 this pass will transform the code into:
3327 x = ASSERT_EXPR <x, x < y>
3332 y = ASSERT_EXPR <y, x <= y>
3336 The idea is that once copy and constant propagation have run, other
3337 optimizations will be able to determine what ranges of values can 'x'
3338 take in different paths of the code, simply by checking the reaching
3339 definition of 'x'. */
3342 insert_range_assertions (void)
3348 found_in_subgraph = sbitmap_alloc (num_ssa_names);
3349 sbitmap_zero (found_in_subgraph);
3351 blocks_visited = sbitmap_alloc (last_basic_block);
3352 sbitmap_zero (blocks_visited);
3354 need_assert_for = BITMAP_ALLOC (NULL);
3355 asserts_for = XNEWVEC (assert_locus_t, num_ssa_names);
3356 memset (asserts_for, 0, num_ssa_names * sizeof (assert_locus_t));
3358 calculate_dominance_info (CDI_DOMINATORS);
3360 update_ssa_p = false;
3361 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3362 if (find_assert_locations (e->dest))
3363 update_ssa_p = true;
3367 process_assert_insertions ();
3368 update_ssa (TODO_update_ssa_no_phi);
3371 if (dump_file && (dump_flags & TDF_DETAILS))
3373 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
3374 dump_function_to_file (current_function_decl, dump_file, dump_flags);
3377 sbitmap_free (found_in_subgraph);
3379 BITMAP_FREE (need_assert_for);
3383 /* Convert range assertion expressions into the implied copies and
3384 copy propagate away the copies. Doing the trivial copy propagation
3385 here avoids the need to run the full copy propagation pass after
3388 FIXME, this will eventually lead to copy propagation removing the
3389 names that had useful range information attached to them. For
3390 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
3391 then N_i will have the range [3, +INF].
3393 However, by converting the assertion into the implied copy
3394 operation N_i = N_j, we will then copy-propagate N_j into the uses
3395 of N_i and lose the range information. We may want to hold on to
3396 ASSERT_EXPRs a little while longer as the ranges could be used in
3397 things like jump threading.
3399 The problem with keeping ASSERT_EXPRs around is that passes after
3400 VRP need to handle them appropriately.
3402 Another approach would be to make the range information a first
3403 class property of the SSA_NAME so that it can be queried from
3404 any pass. This is made somewhat more complex by the need for
3405 multiple ranges to be associated with one SSA_NAME. */
3408 remove_range_assertions (void)
3411 block_stmt_iterator si;
3413 /* Note that the BSI iterator bump happens at the bottom of the
3414 loop and no bump is necessary if we're removing the statement
3415 referenced by the current BSI. */
3417 for (si = bsi_start (bb); !bsi_end_p (si);)
3419 tree stmt = bsi_stmt (si);
3422 if (TREE_CODE (stmt) == MODIFY_EXPR
3423 && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
3425 tree rhs = TREE_OPERAND (stmt, 1), var;
3426 tree cond = fold (ASSERT_EXPR_COND (rhs));
3427 use_operand_p use_p;
3428 imm_use_iterator iter;
3430 gcc_assert (cond != boolean_false_node);
3432 /* Propagate the RHS into every use of the LHS. */
3433 var = ASSERT_EXPR_VAR (rhs);
3434 FOR_EACH_IMM_USE_STMT (use_stmt, iter, TREE_OPERAND (stmt, 0))
3435 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
3437 SET_USE (use_p, var);
3438 gcc_assert (TREE_CODE (var) == SSA_NAME);
3441 /* And finally, remove the copy, it is not needed. */
3442 bsi_remove (&si, true);
3448 sbitmap_free (blocks_visited);
3452 /* Return true if STMT is interesting for VRP. */
3455 stmt_interesting_for_vrp (tree stmt)
3457 if (TREE_CODE (stmt) == PHI_NODE
3458 && is_gimple_reg (PHI_RESULT (stmt))
3459 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
3460 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
3462 else if (TREE_CODE (stmt) == MODIFY_EXPR)
3464 tree lhs = TREE_OPERAND (stmt, 0);
3465 tree rhs = TREE_OPERAND (stmt, 1);
3467 /* In general, assignments with virtual operands are not useful
3468 for deriving ranges, with the obvious exception of calls to
3469 builtin functions. */
3470 if (TREE_CODE (lhs) == SSA_NAME
3471 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3472 || POINTER_TYPE_P (TREE_TYPE (lhs)))
3473 && ((TREE_CODE (rhs) == CALL_EXPR
3474 && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR
3475 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))
3476 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)))
3477 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)))
3480 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3487 /* Initialize local data structures for VRP. */
3490 vrp_initialize (void)
3494 vr_value = XNEWVEC (value_range_t *, num_ssa_names);
3495 memset (vr_value, 0, num_ssa_names * sizeof (value_range_t *));
3499 block_stmt_iterator si;
3502 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3504 if (!stmt_interesting_for_vrp (phi))
3506 tree lhs = PHI_RESULT (phi);
3507 set_value_range_to_varying (get_value_range (lhs));
3508 DONT_SIMULATE_AGAIN (phi) = true;
3511 DONT_SIMULATE_AGAIN (phi) = false;
3514 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3516 tree stmt = bsi_stmt (si);
3518 if (!stmt_interesting_for_vrp (stmt))
3522 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
3523 set_value_range_to_varying (get_value_range (def));
3524 DONT_SIMULATE_AGAIN (stmt) = true;
3528 DONT_SIMULATE_AGAIN (stmt) = false;
3535 /* Visit assignment STMT. If it produces an interesting range, record
3536 the SSA name in *OUTPUT_P. */
3538 static enum ssa_prop_result
3539 vrp_visit_assignment (tree stmt, tree *output_p)
3544 lhs = TREE_OPERAND (stmt, 0);
3545 rhs = TREE_OPERAND (stmt, 1);
3547 /* We only keep track of ranges in integral and pointer types. */
3548 if (TREE_CODE (lhs) == SSA_NAME
3549 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3550 /* It is valid to have NULL MIN/MAX values on a type. See
3551 build_range_type. */
3552 && TYPE_MIN_VALUE (TREE_TYPE (lhs))
3553 && TYPE_MAX_VALUE (TREE_TYPE (lhs)))
3554 || POINTER_TYPE_P (TREE_TYPE (lhs))))
3557 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3559 extract_range_from_expr (&new_vr, rhs);
3561 /* If STMT is inside a loop, we may be able to know something
3562 else about the range of LHS by examining scalar evolution
3564 if (current_loops && (l = loop_containing_stmt (stmt)))
3565 adjust_range_with_scev (&new_vr, l, stmt, lhs);
3567 if (update_value_range (lhs, &new_vr))
3571 if (dump_file && (dump_flags & TDF_DETAILS))
3573 fprintf (dump_file, "Found new range for ");
3574 print_generic_expr (dump_file, lhs, 0);
3575 fprintf (dump_file, ": ");
3576 dump_value_range (dump_file, &new_vr);
3577 fprintf (dump_file, "\n\n");
3580 if (new_vr.type == VR_VARYING)
3581 return SSA_PROP_VARYING;
3583 return SSA_PROP_INTERESTING;
3586 return SSA_PROP_NOT_INTERESTING;
3589 /* Every other statement produces no useful ranges. */
3590 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3591 set_value_range_to_varying (get_value_range (def));
3593 return SSA_PROP_VARYING;
3597 /* Compare all the value ranges for names equivalent to VAR with VAL
3598 using comparison code COMP. Return the same value returned by
3599 compare_range_with_value. */
3602 compare_name_with_value (enum tree_code comp, tree var, tree val)
3609 t = retval = NULL_TREE;
3611 /* Get the set of equivalences for VAR. */
3612 e = get_value_range (var)->equiv;
3614 /* Add VAR to its own set of equivalences so that VAR's value range
3615 is processed by this loop (otherwise, we would have to replicate
3616 the body of the loop just to check VAR's value range). */
3617 bitmap_set_bit (e, SSA_NAME_VERSION (var));
3619 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
3621 value_range_t equiv_vr = *(vr_value[i]);
3623 /* If name N_i does not have a valid range, use N_i as its own
3624 range. This allows us to compare against names that may
3625 have N_i in their ranges. */
3626 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
3628 equiv_vr.type = VR_RANGE;
3629 equiv_vr.min = ssa_name (i);
3630 equiv_vr.max = ssa_name (i);
3633 t = compare_range_with_value (comp, &equiv_vr, val);
3636 /* If we get different answers from different members
3637 of the equivalence set this check must be in a dead
3638 code region. Folding it to a trap representation
3639 would be correct here. For now just return don't-know. */
3650 /* Remove VAR from its own equivalence set. */
3651 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
3656 /* We couldn't find a non-NULL value for the predicate. */
3661 /* Given a comparison code COMP and names N1 and N2, compare all the
3662 ranges equivalent to N1 against all the ranges equivalent to N2
3663 to determine the value of N1 COMP N2. Return the same value
3664 returned by compare_ranges. */
3667 compare_names (enum tree_code comp, tree n1, tree n2)
3671 bitmap_iterator bi1, bi2;
3674 /* Compare the ranges of every name equivalent to N1 against the
3675 ranges of every name equivalent to N2. */
3676 e1 = get_value_range (n1)->equiv;
3677 e2 = get_value_range (n2)->equiv;
3679 /* Add N1 and N2 to their own set of equivalences to avoid
3680 duplicating the body of the loop just to check N1 and N2
3682 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
3683 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
3685 /* If the equivalence sets have a common intersection, then the two
3686 names can be compared without checking their ranges. */
3687 if (bitmap_intersect_p (e1, e2))
3689 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3690 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3692 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
3694 : boolean_false_node;
3697 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3698 N2 to their own set of equivalences to avoid duplicating the body
3699 of the loop just to check N1 and N2 ranges. */
3700 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
3702 value_range_t vr1 = *(vr_value[i1]);
3704 /* If the range is VARYING or UNDEFINED, use the name itself. */
3705 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
3707 vr1.type = VR_RANGE;
3708 vr1.min = ssa_name (i1);
3709 vr1.max = ssa_name (i1);
3712 t = retval = NULL_TREE;
3713 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
3715 value_range_t vr2 = *(vr_value[i2]);
3717 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
3719 vr2.type = VR_RANGE;
3720 vr2.min = ssa_name (i2);
3721 vr2.max = ssa_name (i2);
3724 t = compare_ranges (comp, &vr1, &vr2);
3727 /* If we get different answers from different members
3728 of the equivalence set this check must be in a dead
3729 code region. Folding it to a trap representation
3730 would be correct here. For now just return don't-know. */
3734 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3735 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3744 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3745 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3750 /* None of the equivalent ranges are useful in computing this
3752 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3753 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3758 /* Given a conditional predicate COND, try to determine if COND yields
3759 true or false based on the value ranges of its operands. Return
3760 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3761 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3762 NULL if the conditional cannot be evaluated at compile time.
3764 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3765 the operands in COND are used when trying to compute its value.
3766 This is only used during final substitution. During propagation,
3767 we only check the range of each variable and not its equivalents. */
3770 vrp_evaluate_conditional (tree cond, bool use_equiv_p)
3772 gcc_assert (TREE_CODE (cond) == SSA_NAME
3773 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
3775 if (TREE_CODE (cond) == SSA_NAME)
3781 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node);
3784 value_range_t *vr = get_value_range (cond);
3785 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node);
3788 /* If COND has a known boolean range, return it. */
3792 /* Otherwise, if COND has a symbolic range of exactly one value,
3794 vr = get_value_range (cond);
3795 if (vr->type == VR_RANGE && vr->min == vr->max)
3800 tree op0 = TREE_OPERAND (cond, 0);
3801 tree op1 = TREE_OPERAND (cond, 1);
3803 /* We only deal with integral and pointer types. */
3804 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
3805 && !POINTER_TYPE_P (TREE_TYPE (op0)))
3810 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
3811 return compare_names (TREE_CODE (cond), op0, op1);
3812 else if (TREE_CODE (op0) == SSA_NAME)
3813 return compare_name_with_value (TREE_CODE (cond), op0, op1);
3814 else if (TREE_CODE (op1) == SSA_NAME)
3815 return compare_name_with_value (
3816 swap_tree_comparison (TREE_CODE (cond)), op1, op0);
3820 value_range_t *vr0, *vr1;
3822 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
3823 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
3826 return compare_ranges (TREE_CODE (cond), vr0, vr1);
3827 else if (vr0 && vr1 == NULL)
3828 return compare_range_with_value (TREE_CODE (cond), vr0, op1);
3829 else if (vr0 == NULL && vr1)
3830 return compare_range_with_value (
3831 swap_tree_comparison (TREE_CODE (cond)), vr1, op0);
3835 /* Anything else cannot be computed statically. */
3840 /* Visit conditional statement STMT. If we can determine which edge
3841 will be taken out of STMT's basic block, record it in
3842 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3843 SSA_PROP_VARYING. */
3845 static enum ssa_prop_result
3846 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
3850 *taken_edge_p = NULL;
3852 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3853 add ASSERT_EXPRs for them. */
3854 if (TREE_CODE (stmt) == SWITCH_EXPR)
3855 return SSA_PROP_VARYING;
3857 cond = COND_EXPR_COND (stmt);
3859 if (dump_file && (dump_flags & TDF_DETAILS))
3864 fprintf (dump_file, "\nVisiting conditional with predicate: ");
3865 print_generic_expr (dump_file, cond, 0);
3866 fprintf (dump_file, "\nWith known ranges\n");
3868 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
3870 fprintf (dump_file, "\t");
3871 print_generic_expr (dump_file, use, 0);
3872 fprintf (dump_file, ": ");
3873 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
3876 fprintf (dump_file, "\n");
3879 /* Compute the value of the predicate COND by checking the known
3880 ranges of each of its operands.
3882 Note that we cannot evaluate all the equivalent ranges here
3883 because those ranges may not yet be final and with the current
3884 propagation strategy, we cannot determine when the value ranges
3885 of the names in the equivalence set have changed.
3887 For instance, given the following code fragment
3891 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3895 Assume that on the first visit to i_14, i_5 has the temporary
3896 range [8, 8] because the second argument to the PHI function is
3897 not yet executable. We derive the range ~[0, 0] for i_14 and the
3898 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3899 the first time, since i_14 is equivalent to the range [8, 8], we
3900 determine that the predicate is always false.
3902 On the next round of propagation, i_13 is determined to be
3903 VARYING, which causes i_5 to drop down to VARYING. So, another
3904 visit to i_14 is scheduled. In this second visit, we compute the
3905 exact same range and equivalence set for i_14, namely ~[0, 0] and
3906 { i_5 }. But we did not have the previous range for i_5
3907 registered, so vrp_visit_assignment thinks that the range for
3908 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3909 is not visited again, which stops propagation from visiting
3910 statements in the THEN clause of that if().
3912 To properly fix this we would need to keep the previous range
3913 value for the names in the equivalence set. This way we would've
3914 discovered that from one visit to the other i_5 changed from
3915 range [8, 8] to VR_VARYING.
3917 However, fixing this apparent limitation may not be worth the
3918 additional checking. Testing on several code bases (GCC, DLV,
3919 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3920 4 more predicates folded in SPEC. */
3921 val = vrp_evaluate_conditional (cond, false);
3923 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
3925 if (dump_file && (dump_flags & TDF_DETAILS))
3927 fprintf (dump_file, "\nPredicate evaluates to: ");
3928 if (val == NULL_TREE)
3929 fprintf (dump_file, "DON'T KNOW\n");
3931 print_generic_stmt (dump_file, val, 0);
3934 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
3938 /* Evaluate statement STMT. If the statement produces a useful range,
3939 return SSA_PROP_INTERESTING and record the SSA name with the
3940 interesting range into *OUTPUT_P.
3942 If STMT is a conditional branch and we can determine its truth
3943 value, the taken edge is recorded in *TAKEN_EDGE_P.
3945 If STMT produces a varying value, return SSA_PROP_VARYING. */
3947 static enum ssa_prop_result
3948 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
3954 if (dump_file && (dump_flags & TDF_DETAILS))
3956 fprintf (dump_file, "\nVisiting statement:\n");
3957 print_generic_stmt (dump_file, stmt, dump_flags);
3958 fprintf (dump_file, "\n");
3961 ann = stmt_ann (stmt);
3962 if (TREE_CODE (stmt) == MODIFY_EXPR)
3964 tree rhs = TREE_OPERAND (stmt, 1);
3966 /* In general, assignments with virtual operands are not useful
3967 for deriving ranges, with the obvious exception of calls to
3968 builtin functions. */
3969 if ((TREE_CODE (rhs) == CALL_EXPR
3970 && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR
3971 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))
3972 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)))
3973 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3974 return vrp_visit_assignment (stmt, output_p);
3976 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3977 return vrp_visit_cond_stmt (stmt, taken_edge_p);
3979 /* All other statements produce nothing of interest for VRP, so mark
3980 their outputs varying and prevent further simulation. */
3981 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3982 set_value_range_to_varying (get_value_range (def));
3984 return SSA_PROP_VARYING;
3988 /* Meet operation for value ranges. Given two value ranges VR0 and
3989 VR1, store in VR0 the result of meeting VR0 and VR1.
3991 The meeting rules are as follows:
3993 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
3995 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
3996 union of VR0 and VR1. */
3999 vrp_meet (value_range_t *vr0, value_range_t *vr1)
4001 if (vr0->type == VR_UNDEFINED)
4003 copy_value_range (vr0, vr1);
4007 if (vr1->type == VR_UNDEFINED)
4009 /* Nothing to do. VR0 already has the resulting range. */
4013 if (vr0->type == VR_VARYING)
4015 /* Nothing to do. VR0 already has the resulting range. */
4019 if (vr1->type == VR_VARYING)
4021 set_value_range_to_varying (vr0);
4025 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
4027 /* If VR0 and VR1 have a non-empty intersection, compute the
4028 union of both ranges. */
4029 if (value_ranges_intersect_p (vr0, vr1))
4034 /* The lower limit of the new range is the minimum of the
4035 two ranges. If they cannot be compared, the result is
4037 cmp = compare_values (vr0->min, vr1->min);
4038 if (cmp == 0 || cmp == 1)
4044 set_value_range_to_varying (vr0);
4048 /* Similarly, the upper limit of the new range is the
4049 maximum of the two ranges. If they cannot be compared,
4050 the result is VARYING. */
4051 cmp = compare_values (vr0->max, vr1->max);
4052 if (cmp == 0 || cmp == -1)
4058 set_value_range_to_varying (vr0);
4062 /* The resulting set of equivalences is the intersection of
4064 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4065 bitmap_and_into (vr0->equiv, vr1->equiv);
4066 else if (vr0->equiv && !vr1->equiv)
4067 bitmap_clear (vr0->equiv);
4069 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
4074 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
4076 /* Two anti-ranges meet only if they are both identical. */
4077 if (compare_values (vr0->min, vr1->min) == 0
4078 && compare_values (vr0->max, vr1->max) == 0
4079 && compare_values (vr0->min, vr0->max) == 0)
4081 /* The resulting set of equivalences is the intersection of
4083 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4084 bitmap_and_into (vr0->equiv, vr1->equiv);
4085 else if (vr0->equiv && !vr1->equiv)
4086 bitmap_clear (vr0->equiv);
4091 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
4093 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
4094 meet only if the ranges have an empty intersection. The
4095 result of the meet operation is the anti-range. */
4096 if (!symbolic_range_p (vr0)
4097 && !symbolic_range_p (vr1)
4098 && !value_ranges_intersect_p (vr0, vr1))
4100 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
4101 set. We need to compute the intersection of the two
4102 equivalence sets. */
4103 if (vr1->type == VR_ANTI_RANGE)
4104 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
4106 /* The resulting set of equivalences is the intersection of
4108 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4109 bitmap_and_into (vr0->equiv, vr1->equiv);
4110 else if (vr0->equiv && !vr1->equiv)
4111 bitmap_clear (vr0->equiv);
4122 /* The two range VR0 and VR1 do not meet. Before giving up and
4123 setting the result to VARYING, see if we can at least derive a
4124 useful anti-range. FIXME, all this nonsense about distinguishing
4125 anti-ranges from ranges is necessary because of the odd
4126 semantics of range_includes_zero_p and friends. */
4127 if (!symbolic_range_p (vr0)
4128 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
4129 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
4130 && !symbolic_range_p (vr1)
4131 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
4132 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
4134 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
4136 /* Since this meet operation did not result from the meeting of
4137 two equivalent names, VR0 cannot have any equivalences. */
4139 bitmap_clear (vr0->equiv);
4142 set_value_range_to_varying (vr0);
4146 /* Visit all arguments for PHI node PHI that flow through executable
4147 edges. If a valid value range can be derived from all the incoming
4148 value ranges, set a new range for the LHS of PHI. */
4150 static enum ssa_prop_result
4151 vrp_visit_phi_node (tree phi)
4154 tree lhs = PHI_RESULT (phi);
4155 value_range_t *lhs_vr = get_value_range (lhs);
4156 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
4158 copy_value_range (&vr_result, lhs_vr);
4160 if (dump_file && (dump_flags & TDF_DETAILS))
4162 fprintf (dump_file, "\nVisiting PHI node: ");
4163 print_generic_expr (dump_file, phi, dump_flags);
4166 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
4168 edge e = PHI_ARG_EDGE (phi, i);
4170 if (dump_file && (dump_flags & TDF_DETAILS))
4173 "\n Argument #%d (%d -> %d %sexecutable)\n",
4174 i, e->src->index, e->dest->index,
4175 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
4178 if (e->flags & EDGE_EXECUTABLE)
4180 tree arg = PHI_ARG_DEF (phi, i);
4181 value_range_t vr_arg;
4183 if (TREE_CODE (arg) == SSA_NAME)
4184 vr_arg = *(get_value_range (arg));
4187 vr_arg.type = VR_RANGE;
4190 vr_arg.equiv = NULL;
4193 if (dump_file && (dump_flags & TDF_DETAILS))
4195 fprintf (dump_file, "\t");
4196 print_generic_expr (dump_file, arg, dump_flags);
4197 fprintf (dump_file, "\n\tValue: ");
4198 dump_value_range (dump_file, &vr_arg);
4199 fprintf (dump_file, "\n");
4202 vrp_meet (&vr_result, &vr_arg);
4204 if (vr_result.type == VR_VARYING)
4209 if (vr_result.type == VR_VARYING)
4212 /* To prevent infinite iterations in the algorithm, derive ranges
4213 when the new value is slightly bigger or smaller than the
4215 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE)
4217 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
4219 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
4220 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
4222 /* If the new minimum is smaller or larger than the previous
4223 one, go all the way to -INF. In the first case, to avoid
4224 iterating millions of times to reach -INF, and in the
4225 other case to avoid infinite bouncing between different
4227 if (cmp_min > 0 || cmp_min < 0)
4228 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
4230 /* Similarly, if the new maximum is smaller or larger than
4231 the previous one, go all the way to +INF. */
4232 if (cmp_max < 0 || cmp_max > 0)
4233 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
4235 /* If we ended up with a (-INF, +INF) range, set it to
4237 if (vr_result.min == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))
4238 && vr_result.max == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)))
4243 /* If the new range is different than the previous value, keep
4245 if (update_value_range (lhs, &vr_result))
4246 return SSA_PROP_INTERESTING;
4248 /* Nothing changed, don't add outgoing edges. */
4249 return SSA_PROP_NOT_INTERESTING;
4251 /* No match found. Set the LHS to VARYING. */
4253 set_value_range_to_varying (lhs_vr);
4254 return SSA_PROP_VARYING;
4257 /* Simplify a division or modulo operator to a right shift or
4258 bitwise and if the first operand is unsigned or is greater
4259 than zero and the second operand is an exact power of two. */
4262 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
4265 tree op = TREE_OPERAND (rhs, 0);
4266 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
4268 if (TYPE_UNSIGNED (TREE_TYPE (op)))
4270 val = integer_one_node;
4274 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node);
4277 if (val && integer_onep (val))
4280 tree op0 = TREE_OPERAND (rhs, 0);
4281 tree op1 = TREE_OPERAND (rhs, 1);
4283 if (rhs_code == TRUNC_DIV_EXPR)
4285 t = build_int_cst (NULL_TREE, tree_log2 (op1));
4286 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
4290 t = build_int_cst (TREE_TYPE (op1), 1);
4291 t = int_const_binop (MINUS_EXPR, op1, t, 0);
4292 t = fold_convert (TREE_TYPE (op0), t);
4293 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
4296 TREE_OPERAND (stmt, 1) = t;
4301 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
4302 ABS_EXPR. If the operand is <= 0, then simplify the
4303 ABS_EXPR into a NEGATE_EXPR. */
4306 simplify_abs_using_ranges (tree stmt, tree rhs)
4309 tree op = TREE_OPERAND (rhs, 0);
4310 tree type = TREE_TYPE (op);
4311 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
4313 if (TYPE_UNSIGNED (type))
4315 val = integer_zero_node;
4319 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node);
4322 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node);
4326 if (integer_zerop (val))
4327 val = integer_one_node;
4328 else if (integer_onep (val))
4329 val = integer_zero_node;
4334 && (integer_onep (val) || integer_zerop (val)))
4338 if (integer_onep (val))
4339 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
4343 TREE_OPERAND (stmt, 1) = t;
4349 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
4350 a known value range VR.
4352 If there is one and only one value which will satisfy the
4353 conditional, then return that value. Else return NULL. */
4356 test_for_singularity (enum tree_code cond_code, tree op0,
4357 tree op1, value_range_t *vr)
4362 /* Extract minimum/maximum values which satisfy the
4363 the conditional as it was written. */
4364 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
4366 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
4369 if (cond_code == LT_EXPR)
4371 tree one = build_int_cst (TREE_TYPE (op0), 1);
4372 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
4375 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
4377 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
4380 if (cond_code == GT_EXPR)
4382 tree one = build_int_cst (TREE_TYPE (op0), 1);
4383 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
4387 /* Now refine the minimum and maximum values using any
4388 value range information we have for op0. */
4391 if (compare_values (vr->min, min) == -1)
4395 if (compare_values (vr->max, max) == 1)
4400 /* If the new min/max values have converged to a single value,
4401 then there is only one value which can satisfy the condition,
4402 return that value. */
4403 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
4409 /* Simplify a conditional using a relational operator to an equality
4410 test if the range information indicates only one value can satisfy
4411 the original conditional. */
4414 simplify_cond_using_ranges (tree stmt)
4416 tree cond = COND_EXPR_COND (stmt);
4417 tree op0 = TREE_OPERAND (cond, 0);
4418 tree op1 = TREE_OPERAND (cond, 1);
4419 enum tree_code cond_code = TREE_CODE (cond);
4421 if (cond_code != NE_EXPR
4422 && cond_code != EQ_EXPR
4423 && TREE_CODE (op0) == SSA_NAME
4424 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
4425 && is_gimple_min_invariant (op1))
4427 value_range_t *vr = get_value_range (op0);
4429 /* If we have range information for OP0, then we might be
4430 able to simplify this conditional. */
4431 if (vr->type == VR_RANGE)
4433 tree new = test_for_singularity (cond_code, op0, op1, vr);
4439 fprintf (dump_file, "Simplified relational ");
4440 print_generic_expr (dump_file, cond, 0);
4441 fprintf (dump_file, " into ");
4444 COND_EXPR_COND (stmt)
4445 = build2 (EQ_EXPR, boolean_type_node, op0, new);
4450 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4451 fprintf (dump_file, "\n");
4457 /* Try again after inverting the condition. We only deal
4458 with integral types here, so no need to worry about
4459 issues with inverting FP comparisons. */
4460 cond_code = invert_tree_comparison (cond_code, false);
4461 new = test_for_singularity (cond_code, op0, op1, vr);
4467 fprintf (dump_file, "Simplified relational ");
4468 print_generic_expr (dump_file, cond, 0);
4469 fprintf (dump_file, " into ");
4472 COND_EXPR_COND (stmt)
4473 = build2 (NE_EXPR, boolean_type_node, op0, new);
4478 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4479 fprintf (dump_file, "\n");
4488 /* Simplify STMT using ranges if possible. */
4491 simplify_stmt_using_ranges (tree stmt)
4493 if (TREE_CODE (stmt) == MODIFY_EXPR)
4495 tree rhs = TREE_OPERAND (stmt, 1);
4496 enum tree_code rhs_code = TREE_CODE (rhs);
4498 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
4499 and BIT_AND_EXPR respectively if the first operand is greater
4500 than zero and the second operand is an exact power of two. */
4501 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
4502 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
4503 && integer_pow2p (TREE_OPERAND (rhs, 1)))
4504 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
4506 /* Transform ABS (X) into X or -X as appropriate. */
4507 if (rhs_code == ABS_EXPR
4508 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
4509 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
4510 simplify_abs_using_ranges (stmt, rhs);
4512 else if (TREE_CODE (stmt) == COND_EXPR
4513 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
4515 simplify_cond_using_ranges (stmt);
4519 /* Stack of dest,src equivalency pairs that need to be restored after
4520 each attempt to thread a block's incoming edge to an outgoing edge.
4522 A NULL entry is used to mark the end of pairs which need to be
4524 static VEC(tree,heap) *stack;
4526 /* A trivial wrapper so that we can present the generic jump
4527 threading code with a simple API for simplifying statements. */
4529 simplify_stmt_for_jump_threading (tree stmt)
4531 /* We only use VRP information to simplify conditionals. This is
4532 overly conservative, but it's unclear if doing more would be
4533 worth the compile time cost. */
4534 if (TREE_CODE (stmt) != COND_EXPR)
4537 return vrp_evaluate_conditional (COND_EXPR_COND (stmt), true);
4540 /* Blocks which have more than one predecessor and more than
4541 one successor present jump threading opportunities. ie,
4542 when the block is reached from a specific predecessor, we
4543 may be able to determine which of the outgoing edges will
4544 be traversed. When this optimization applies, we are able
4545 to avoid conditionals at runtime and we may expose secondary
4546 optimization opportunities.
4548 This routine is effectively a driver for the generic jump
4549 threading code. It basically just presents the generic code
4550 with edges that may be suitable for jump threading.
4552 Unlike DOM, we do not iterate VRP if jump threading was successful.
4553 While iterating may expose new opportunities for VRP, it is expected
4554 those opportunities would be very limited and the compile time cost
4555 to expose those opportunities would be significant.
4557 As jump threading opportunities are discovered, they are registered
4558 for later realization. */
4561 identify_jump_threads (void)
4566 /* Ugh. When substituting values earlier in this pass we can
4567 wipe the dominance information. So rebuild the dominator
4568 information as we need it within the jump threading code. */
4569 calculate_dominance_info (CDI_DOMINATORS);
4571 /* We do not allow VRP information to be used for jump threading
4572 across a back edge in the CFG. Otherwise it becomes too
4573 difficult to avoid eliminating loop exit tests. Of course
4574 EDGE_DFS_BACK is not accurate at this time so we have to
4576 mark_dfs_back_edges ();
4578 /* Allocate our unwinder stack to unwind any temporary equivalences
4579 that might be recorded. */
4580 stack = VEC_alloc (tree, heap, 20);
4582 /* To avoid lots of silly node creation, we create a single
4583 conditional and just modify it in-place when attempting to
4585 dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL);
4586 dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL);
4588 /* Walk through all the blocks finding those which present a
4589 potential jump threading opportunity. We could set this up
4590 as a dominator walker and record data during the walk, but
4591 I doubt it's worth the effort for the classes of jump
4592 threading opportunities we are trying to identify at this
4593 point in compilation. */
4598 /* If the generic jump threading code does not find this block
4599 interesting, then there is nothing to do. */
4600 if (! potentially_threadable_block (bb))
4603 /* We only care about blocks ending in a COND_EXPR. While there
4604 may be some value in handling SWITCH_EXPR here, I doubt it's
4605 terribly important. */
4606 last = bsi_stmt (bsi_last (bb));
4607 if (TREE_CODE (last) != COND_EXPR)
4610 /* We're basically looking for any kind of conditional with
4611 integral type arguments. */
4612 cond = COND_EXPR_COND (last);
4613 if ((TREE_CODE (cond) == SSA_NAME
4614 && INTEGRAL_TYPE_P (TREE_TYPE (cond)))
4615 || (COMPARISON_CLASS_P (cond)
4616 && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
4617 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0)))
4618 && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME
4619 || is_gimple_min_invariant (TREE_OPERAND (cond, 1)))
4620 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
4625 /* We've got a block with multiple predecessors and multiple
4626 successors which also ends in a suitable conditional. For
4627 each predecessor, see if we can thread it to a specific
4629 FOR_EACH_EDGE (e, ei, bb->preds)
4631 /* Do not thread across back edges or abnormal edges
4633 if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
4636 thread_across_edge (dummy, e, true,
4638 simplify_stmt_for_jump_threading);
4643 /* We do not actually update the CFG or SSA graphs at this point as
4644 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
4645 handle ASSERT_EXPRs gracefully. */
4648 /* We identified all the jump threading opportunities earlier, but could
4649 not transform the CFG at that time. This routine transforms the
4650 CFG and arranges for the dominator tree to be rebuilt if necessary.
4652 Note the SSA graph update will occur during the normal TODO
4653 processing by the pass manager. */
4655 finalize_jump_threads (void)
4657 bool cfg_altered = false;
4658 cfg_altered = thread_through_all_blocks ();
4660 /* If we threaded jumps, then we need to recompute the dominance
4661 information, to safely do that we must clean up the CFG first. */
4664 free_dominance_info (CDI_DOMINATORS);
4665 cleanup_tree_cfg ();
4666 calculate_dominance_info (CDI_DOMINATORS);
4668 VEC_free (tree, heap, stack);
4672 /* Traverse all the blocks folding conditionals with known ranges. */
4678 prop_value_t *single_val_range;
4679 bool do_value_subst_p;
4683 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
4684 dump_all_value_ranges (dump_file);
4685 fprintf (dump_file, "\n");
4688 /* We may have ended with ranges that have exactly one value. Those
4689 values can be substituted as any other copy/const propagated
4690 value using substitute_and_fold. */
4691 single_val_range = XNEWVEC (prop_value_t, num_ssa_names);
4692 memset (single_val_range, 0, num_ssa_names * sizeof (*single_val_range));
4694 do_value_subst_p = false;
4695 for (i = 0; i < num_ssa_names; i++)
4697 && vr_value[i]->type == VR_RANGE
4698 && vr_value[i]->min == vr_value[i]->max)
4700 single_val_range[i].value = vr_value[i]->min;
4701 do_value_subst_p = true;
4704 if (!do_value_subst_p)
4706 /* We found no single-valued ranges, don't waste time trying to
4707 do single value substitution in substitute_and_fold. */
4708 free (single_val_range);
4709 single_val_range = NULL;
4712 substitute_and_fold (single_val_range, true);
4714 /* We must identify jump threading opportunities before we release
4715 the datastructures built by VRP. */
4716 identify_jump_threads ();
4718 /* Free allocated memory. */
4719 for (i = 0; i < num_ssa_names; i++)
4722 BITMAP_FREE (vr_value[i]->equiv);
4726 free (single_val_range);
4729 /* So that we can distinguish between VRP data being available
4730 and not available. */
4735 /* Main entry point to VRP (Value Range Propagation). This pass is
4736 loosely based on J. R. C. Patterson, ``Accurate Static Branch
4737 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
4738 Programming Language Design and Implementation, pp. 67-78, 1995.
4739 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
4741 This is essentially an SSA-CCP pass modified to deal with ranges
4742 instead of constants.
4744 While propagating ranges, we may find that two or more SSA name
4745 have equivalent, though distinct ranges. For instance,
4748 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
4750 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
4754 In the code above, pointer p_5 has range [q_2, q_2], but from the
4755 code we can also determine that p_5 cannot be NULL and, if q_2 had
4756 a non-varying range, p_5's range should also be compatible with it.
4758 These equivalences are created by two expressions: ASSERT_EXPR and
4759 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
4760 result of another assertion, then we can use the fact that p_5 and
4761 p_4 are equivalent when evaluating p_5's range.
4763 Together with value ranges, we also propagate these equivalences
4764 between names so that we can take advantage of information from
4765 multiple ranges when doing final replacement. Note that this
4766 equivalency relation is transitive but not symmetric.
4768 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
4769 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
4770 in contexts where that assertion does not hold (e.g., in line 6).
4772 TODO, the main difference between this pass and Patterson's is that
4773 we do not propagate edge probabilities. We only compute whether
4774 edges can be taken or not. That is, instead of having a spectrum
4775 of jump probabilities between 0 and 1, we only deal with 0, 1 and
4776 DON'T KNOW. In the future, it may be worthwhile to propagate
4777 probabilities to aid branch prediction. */
4782 insert_range_assertions ();
4784 current_loops = loop_optimizer_init (LOOPS_NORMAL);
4786 scev_initialize (current_loops);
4789 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
4795 loop_optimizer_finalize (current_loops);
4796 current_loops = NULL;
4799 /* ASSERT_EXPRs must be removed before finalizing jump threads
4800 as finalizing jump threads calls the CFG cleanup code which
4801 does not properly handle ASSERT_EXPRs. */
4802 remove_range_assertions ();
4804 /* If we exposed any new variables, go ahead and put them into
4805 SSA form now, before we handle jump threading. This simplifies
4806 interactions between rewriting of _DECL nodes into SSA form
4807 and rewriting SSA_NAME nodes into SSA form after block
4808 duplication and CFG manipulation. */
4809 update_ssa (TODO_update_ssa);
4811 finalize_jump_threads ();
4818 return flag_tree_vrp != 0;
4821 struct tree_opt_pass pass_vrp =
4824 gate_vrp, /* gate */
4825 execute_vrp, /* execute */
4828 0, /* static_pass_number */
4829 TV_TREE_VRP, /* tv_id */
4830 PROP_ssa | PROP_alias, /* properties_required */
4831 0, /* properties_provided */
4832 PROP_smt_usage, /* properties_destroyed */
4833 0, /* todo_flags_start */
4839 | TODO_update_smt_usage, /* todo_flags_finish */