1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005, 2006 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
24 #include "coretypes.h"
29 #include "basic-block.h"
30 #include "tree-flow.h"
31 #include "tree-pass.h"
32 #include "tree-dump.h"
34 #include "diagnostic.h"
36 #include "tree-scalar-evolution.h"
37 #include "tree-ssa-propagate.h"
38 #include "tree-chrec.h"
40 /* Set of SSA names found during the dominator traversal of a
41 sub-graph in find_assert_locations. */
42 static sbitmap found_in_subgraph;
44 /* Local functions. */
45 static int compare_values (tree val1, tree val2);
47 /* Location information for ASSERT_EXPRs. Each instance of this
48 structure describes an ASSERT_EXPR for an SSA name. Since a single
49 SSA name may have more than one assertion associated with it, these
50 locations are kept in a linked list attached to the corresponding
54 /* Basic block where the assertion would be inserted. */
57 /* Some assertions need to be inserted on an edge (e.g., assertions
58 generated by COND_EXPRs). In those cases, BB will be NULL. */
61 /* Pointer to the statement that generated this assertion. */
62 block_stmt_iterator si;
64 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
65 enum tree_code comp_code;
67 /* Value being compared against. */
70 /* Next node in the linked list. */
71 struct assert_locus_d *next;
74 typedef struct assert_locus_d *assert_locus_t;
76 /* If bit I is present, it means that SSA name N_i has a list of
77 assertions that should be inserted in the IL. */
78 static bitmap need_assert_for;
80 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
81 holds a list of ASSERT_LOCUS_T nodes that describe where
82 ASSERT_EXPRs for SSA name N_I should be inserted. */
83 static assert_locus_t *asserts_for;
85 /* Set of blocks visited in find_assert_locations. Used to avoid
86 visiting the same block more than once. */
87 static sbitmap blocks_visited;
89 /* Value range array. After propagation, VR_VALUE[I] holds the range
90 of values that SSA name N_I may take. */
91 static value_range_t **vr_value;
94 /* Return true if ARG is marked with the nonnull attribute in the
95 current function signature. */
98 nonnull_arg_p (tree arg)
100 tree t, attrs, fntype;
101 unsigned HOST_WIDE_INT arg_num;
103 gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
105 fntype = TREE_TYPE (current_function_decl);
106 attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype));
108 /* If "nonnull" wasn't specified, we know nothing about the argument. */
109 if (attrs == NULL_TREE)
112 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
113 if (TREE_VALUE (attrs) == NULL_TREE)
116 /* Get the position number for ARG in the function signature. */
117 for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl);
119 t = TREE_CHAIN (t), arg_num++)
125 gcc_assert (t == arg);
127 /* Now see if ARG_NUM is mentioned in the nonnull list. */
128 for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
130 if (compare_tree_int (TREE_VALUE (t), arg_num) == 0)
138 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
141 set_value_range (value_range_t *vr, enum value_range_type t, tree min,
142 tree max, bitmap equiv)
144 #if defined ENABLE_CHECKING
145 /* Check the validity of the range. */
146 if (t == VR_RANGE || t == VR_ANTI_RANGE)
150 gcc_assert (min && max);
152 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
153 gcc_assert (min != TYPE_MIN_VALUE (TREE_TYPE (min))
154 || max != TYPE_MAX_VALUE (TREE_TYPE (max)));
156 cmp = compare_values (min, max);
157 gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
160 if (t == VR_UNDEFINED || t == VR_VARYING)
161 gcc_assert (min == NULL_TREE && max == NULL_TREE);
163 if (t == VR_UNDEFINED || t == VR_VARYING)
164 gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
171 /* Since updating the equivalence set involves deep copying the
172 bitmaps, only do it if absolutely necessary. */
173 if (vr->equiv == NULL)
174 vr->equiv = BITMAP_ALLOC (NULL);
176 if (equiv != vr->equiv)
178 if (equiv && !bitmap_empty_p (equiv))
179 bitmap_copy (vr->equiv, equiv);
181 bitmap_clear (vr->equiv);
186 /* Copy value range FROM into value range TO. */
189 copy_value_range (value_range_t *to, value_range_t *from)
191 set_value_range (to, from->type, from->min, from->max, from->equiv);
194 /* Set value range VR to a non-negative range of type TYPE. */
197 set_value_range_to_nonnegative (value_range_t *vr, tree type)
199 tree zero = build_int_cst (type, 0);
200 set_value_range (vr, VR_RANGE, zero, TYPE_MAX_VALUE (type), vr->equiv);
203 /* Set value range VR to a non-NULL range of type TYPE. */
206 set_value_range_to_nonnull (value_range_t *vr, tree type)
208 tree zero = build_int_cst (type, 0);
209 set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
213 /* Set value range VR to a NULL range of type TYPE. */
216 set_value_range_to_null (value_range_t *vr, tree type)
218 tree zero = build_int_cst (type, 0);
219 set_value_range (vr, VR_RANGE, zero, zero, vr->equiv);
223 /* Set value range VR to VR_VARYING. */
226 set_value_range_to_varying (value_range_t *vr)
228 vr->type = VR_VARYING;
229 vr->min = vr->max = NULL_TREE;
231 bitmap_clear (vr->equiv);
235 /* Set value range VR to VR_UNDEFINED. */
238 set_value_range_to_undefined (value_range_t *vr)
240 vr->type = VR_UNDEFINED;
241 vr->min = vr->max = NULL_TREE;
243 bitmap_clear (vr->equiv);
247 /* Return value range information for VAR.
249 If we have no values ranges recorded (ie, VRP is not running), then
250 return NULL. Otherwise create an empty range if none existed for VAR. */
252 static value_range_t *
253 get_value_range (tree var)
257 unsigned ver = SSA_NAME_VERSION (var);
259 /* If we have no recorded ranges, then return NULL. */
267 /* Create a default value range. */
268 vr_value[ver] = vr = XNEW (value_range_t);
269 memset (vr, 0, sizeof (*vr));
271 /* Allocate an equivalence set. */
272 vr->equiv = BITMAP_ALLOC (NULL);
274 /* If VAR is a default definition, the variable can take any value
276 sym = SSA_NAME_VAR (var);
277 if (var == default_def (sym))
279 /* Try to use the "nonnull" attribute to create ~[0, 0]
280 anti-ranges for pointers. Note that this is only valid with
281 default definitions of PARM_DECLs. */
282 if (TREE_CODE (sym) == PARM_DECL
283 && POINTER_TYPE_P (TREE_TYPE (sym))
284 && nonnull_arg_p (sym))
285 set_value_range_to_nonnull (vr, TREE_TYPE (sym));
287 set_value_range_to_varying (vr);
294 /* Update the value range and equivalence set for variable VAR to
295 NEW_VR. Return true if NEW_VR is different from VAR's previous
298 NOTE: This function assumes that NEW_VR is a temporary value range
299 object created for the sole purpose of updating VAR's range. The
300 storage used by the equivalence set from NEW_VR will be freed by
301 this function. Do not call update_value_range when NEW_VR
302 is the range object associated with another SSA name. */
305 update_value_range (tree var, value_range_t *new_vr)
307 value_range_t *old_vr;
310 /* Update the value range, if necessary. */
311 old_vr = get_value_range (var);
312 is_new = old_vr->type != new_vr->type
313 || old_vr->min != new_vr->min
314 || old_vr->max != new_vr->max
315 || (old_vr->equiv == NULL && new_vr->equiv)
316 || (old_vr->equiv && new_vr->equiv == NULL)
317 || (!bitmap_equal_p (old_vr->equiv, new_vr->equiv));
320 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
323 BITMAP_FREE (new_vr->equiv);
324 new_vr->equiv = NULL;
330 /* Add VAR and VAR's equivalence set to EQUIV. */
333 add_equivalence (bitmap equiv, tree var)
335 unsigned ver = SSA_NAME_VERSION (var);
336 value_range_t *vr = vr_value[ver];
338 bitmap_set_bit (equiv, ver);
340 bitmap_ior_into (equiv, vr->equiv);
344 /* Return true if VR is ~[0, 0]. */
347 range_is_nonnull (value_range_t *vr)
349 return vr->type == VR_ANTI_RANGE
350 && integer_zerop (vr->min)
351 && integer_zerop (vr->max);
355 /* Return true if VR is [0, 0]. */
358 range_is_null (value_range_t *vr)
360 return vr->type == VR_RANGE
361 && integer_zerop (vr->min)
362 && integer_zerop (vr->max);
366 /* Return true if value range VR involves at least one symbol. */
369 symbolic_range_p (value_range_t *vr)
371 return (!is_gimple_min_invariant (vr->min)
372 || !is_gimple_min_invariant (vr->max));
375 /* Like tree_expr_nonnegative_p, but this function uses value ranges
379 vrp_expr_computes_nonnegative (tree expr)
381 return tree_expr_nonnegative_p (expr);
384 /* Like tree_expr_nonzero_p, but this function uses value ranges
388 vrp_expr_computes_nonzero (tree expr)
390 if (tree_expr_nonzero_p (expr))
393 /* If we have an expression of the form &X->a, then the expression
394 is nonnull if X is nonnull. */
395 if (TREE_CODE (expr) == ADDR_EXPR)
397 tree base = get_base_address (TREE_OPERAND (expr, 0));
399 if (base != NULL_TREE
400 && TREE_CODE (base) == INDIRECT_REF
401 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
403 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
404 if (range_is_nonnull (vr))
413 /* Compare two values VAL1 and VAL2. Return
415 -2 if VAL1 and VAL2 cannot be compared at compile-time,
418 +1 if VAL1 > VAL2, and
421 This is similar to tree_int_cst_compare but supports pointer values
422 and values that cannot be compared at compile time. */
425 compare_values (tree val1, tree val2)
430 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
432 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
433 == POINTER_TYPE_P (TREE_TYPE (val2)));
435 /* Do some limited symbolic comparisons. */
436 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
438 /* We can determine some comparisons against +INF and -INF even
439 if the other value is an expression. */
440 if (val1 == TYPE_MAX_VALUE (TREE_TYPE (val1))
441 && TREE_CODE (val2) == MINUS_EXPR)
443 /* +INF > NAME - CST. */
446 else if (val1 == TYPE_MIN_VALUE (TREE_TYPE (val1))
447 && TREE_CODE (val2) == PLUS_EXPR)
449 /* -INF < NAME + CST. */
452 else if (TREE_CODE (val1) == MINUS_EXPR
453 && val2 == TYPE_MAX_VALUE (TREE_TYPE (val2)))
455 /* NAME - CST < +INF. */
458 else if (TREE_CODE (val1) == PLUS_EXPR
459 && val2 == TYPE_MIN_VALUE (TREE_TYPE (val2)))
461 /* NAME + CST > -INF. */
466 if ((TREE_CODE (val1) == SSA_NAME
467 || TREE_CODE (val1) == PLUS_EXPR
468 || TREE_CODE (val1) == MINUS_EXPR)
469 && (TREE_CODE (val2) == SSA_NAME
470 || TREE_CODE (val2) == PLUS_EXPR
471 || TREE_CODE (val2) == MINUS_EXPR))
475 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
476 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
477 same name, return -2. */
478 if (TREE_CODE (val1) == SSA_NAME)
485 n1 = TREE_OPERAND (val1, 0);
486 c1 = TREE_OPERAND (val1, 1);
489 if (TREE_CODE (val2) == SSA_NAME)
496 n2 = TREE_OPERAND (val2, 0);
497 c2 = TREE_OPERAND (val2, 1);
500 /* Both values must use the same name. */
504 if (TREE_CODE (val1) == SSA_NAME)
506 if (TREE_CODE (val2) == SSA_NAME)
509 else if (TREE_CODE (val2) == PLUS_EXPR)
510 /* NAME < NAME + CST */
512 else if (TREE_CODE (val2) == MINUS_EXPR)
513 /* NAME > NAME - CST */
516 else if (TREE_CODE (val1) == PLUS_EXPR)
518 if (TREE_CODE (val2) == SSA_NAME)
519 /* NAME + CST > NAME */
521 else if (TREE_CODE (val2) == PLUS_EXPR)
522 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
523 return compare_values (c1, c2);
524 else if (TREE_CODE (val2) == MINUS_EXPR)
525 /* NAME + CST1 > NAME - CST2 */
528 else if (TREE_CODE (val1) == MINUS_EXPR)
530 if (TREE_CODE (val2) == SSA_NAME)
531 /* NAME - CST < NAME */
533 else if (TREE_CODE (val2) == PLUS_EXPR)
534 /* NAME - CST1 < NAME + CST2 */
536 else if (TREE_CODE (val2) == MINUS_EXPR)
537 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
538 C1 and C2 are swapped in the call to compare_values. */
539 return compare_values (c2, c1);
545 /* We cannot compare non-constants. */
546 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
549 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
551 /* We cannot compare overflowed values. */
552 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
555 return tree_int_cst_compare (val1, val2);
561 /* First see if VAL1 and VAL2 are not the same. */
562 if (val1 == val2 || operand_equal_p (val1, val2, 0))
565 /* If VAL1 is a lower address than VAL2, return -1. */
566 t = fold_binary (LT_EXPR, boolean_type_node, val1, val2);
567 if (t == boolean_true_node)
570 /* If VAL1 is a higher address than VAL2, return +1. */
571 t = fold_binary (GT_EXPR, boolean_type_node, val1, val2);
572 if (t == boolean_true_node)
575 /* If VAL1 is different than VAL2, return +2. */
576 t = fold_binary (NE_EXPR, boolean_type_node, val1, val2);
577 if (t == boolean_true_node)
585 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
586 0 if VAL is not inside VR,
587 -2 if we cannot tell either way.
589 FIXME, the current semantics of this functions are a bit quirky
590 when taken in the context of VRP. In here we do not care
591 about VR's type. If VR is the anti-range ~[3, 5] the call
592 value_inside_range (4, VR) will return 1.
594 This is counter-intuitive in a strict sense, but the callers
595 currently expect this. They are calling the function
596 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
597 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
600 This also applies to value_ranges_intersect_p and
601 range_includes_zero_p. The semantics of VR_RANGE and
602 VR_ANTI_RANGE should be encoded here, but that also means
603 adapting the users of these functions to the new semantics. */
606 value_inside_range (tree val, value_range_t *vr)
610 cmp1 = compare_values (val, vr->min);
611 if (cmp1 == -2 || cmp1 == 2)
614 cmp2 = compare_values (val, vr->max);
615 if (cmp2 == -2 || cmp2 == 2)
618 return (cmp1 == 0 || cmp1 == 1) && (cmp2 == -1 || cmp2 == 0);
622 /* Return true if value ranges VR0 and VR1 have a non-empty
626 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
628 return (value_inside_range (vr1->min, vr0) == 1
629 || value_inside_range (vr1->max, vr0) == 1
630 || value_inside_range (vr0->min, vr1) == 1
631 || value_inside_range (vr0->max, vr1) == 1);
635 /* Return true if VR includes the value zero, false otherwise. FIXME,
636 currently this will return false for an anti-range like ~[-4, 3].
637 This will be wrong when the semantics of value_inside_range are
638 modified (currently the users of this function expect these
642 range_includes_zero_p (value_range_t *vr)
646 gcc_assert (vr->type != VR_UNDEFINED
647 && vr->type != VR_VARYING
648 && !symbolic_range_p (vr));
650 zero = build_int_cst (TREE_TYPE (vr->min), 0);
651 return (value_inside_range (zero, vr) == 1);
654 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
655 false otherwise or if no value range information is available. */
658 ssa_name_nonnegative_p (tree t)
660 value_range_t *vr = get_value_range (t);
665 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
666 which would return a useful value should be encoded as a VR_RANGE. */
667 if (vr->type == VR_RANGE)
669 int result = compare_values (vr->min, integer_zero_node);
671 return (result == 0 || result == 1);
676 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
677 false otherwise or if no value range information is available. */
680 ssa_name_nonzero_p (tree t)
682 value_range_t *vr = get_value_range (t);
687 /* A VR_RANGE which does not include zero is a nonzero value. */
688 if (vr->type == VR_RANGE && !symbolic_range_p (vr))
689 return ! range_includes_zero_p (vr);
691 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
692 if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr))
693 return range_includes_zero_p (vr);
699 /* When extracting ranges from X_i = ASSERT_EXPR <Y_j, pred>, we will
700 initially consider X_i and Y_j equivalent, so the equivalence set
701 of Y_j is added to the equivalence set of X_i. However, it is
702 possible to have a chain of ASSERT_EXPRs whose predicates are
703 actually incompatible. This is usually the result of nesting of
704 contradictory if-then-else statements. For instance, in PR 24670:
706 count_4 has range [-INF, 63]
710 count_19 = ASSERT_EXPR <count_4, count_4 != 0>
713 count_18 = ASSERT_EXPR <count_19, count_19 > 63>
719 Notice that 'if (count_19 > 63)' is trivially false and will be
720 folded out at the end. However, during propagation, the flowgraph
721 is not cleaned up and so, VRP will evaluate predicates more
722 predicates than necessary, so it must support these
723 inconsistencies. The problem here is that because of the chaining
724 of ASSERT_EXPRs, the equivalency set for count_18 includes count_4.
725 Since count_4 has an incompatible range, we ICE when evaluating the
726 ranges in the equivalency set. So, we need to remove count_4 from
730 fix_equivalence_set (value_range_t *vr_p)
734 bitmap e = vr_p->equiv;
735 bitmap to_remove = BITMAP_ALLOC (NULL);
737 /* Only detect inconsistencies on numeric ranges. */
738 if (vr_p->type == VR_VARYING
739 || vr_p->type == VR_UNDEFINED
740 || symbolic_range_p (vr_p))
743 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
745 value_range_t *equiv_vr = vr_value[i];
747 if (equiv_vr->type == VR_VARYING
748 || equiv_vr->type == VR_UNDEFINED
749 || symbolic_range_p (equiv_vr))
752 if (equiv_vr->type == VR_RANGE
753 && vr_p->type == VR_RANGE
754 && !value_ranges_intersect_p (vr_p, equiv_vr))
755 bitmap_set_bit (to_remove, i);
756 else if ((equiv_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
757 || (equiv_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
759 /* A range and an anti-range have an empty intersection if
760 their end points are the same. FIXME,
761 value_ranges_intersect_p should handle this
763 if (compare_values (equiv_vr->min, vr_p->min) == 0
764 && compare_values (equiv_vr->max, vr_p->max) == 0)
765 bitmap_set_bit (to_remove, i);
769 bitmap_and_compl_into (vr_p->equiv, to_remove);
770 BITMAP_FREE (to_remove);
774 /* Extract value range information from an ASSERT_EXPR EXPR and store
778 extract_range_from_assert (value_range_t *vr_p, tree expr)
780 tree var, cond, limit, min, max, type;
781 value_range_t *var_vr, *limit_vr;
782 enum tree_code cond_code;
784 var = ASSERT_EXPR_VAR (expr);
785 cond = ASSERT_EXPR_COND (expr);
787 gcc_assert (COMPARISON_CLASS_P (cond));
789 /* Find VAR in the ASSERT_EXPR conditional. */
790 if (var == TREE_OPERAND (cond, 0))
792 /* If the predicate is of the form VAR COMP LIMIT, then we just
793 take LIMIT from the RHS and use the same comparison code. */
794 limit = TREE_OPERAND (cond, 1);
795 cond_code = TREE_CODE (cond);
799 /* If the predicate is of the form LIMIT COMP VAR, then we need
800 to flip around the comparison code to create the proper range
802 limit = TREE_OPERAND (cond, 0);
803 cond_code = swap_tree_comparison (TREE_CODE (cond));
806 type = TREE_TYPE (limit);
807 gcc_assert (limit != var);
809 /* For pointer arithmetic, we only keep track of pointer equality
811 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
813 set_value_range_to_varying (vr_p);
817 /* If LIMIT is another SSA name and LIMIT has a range of its own,
818 try to use LIMIT's range to avoid creating symbolic ranges
820 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
822 /* LIMIT's range is only interesting if it has any useful information. */
824 && (limit_vr->type == VR_UNDEFINED
825 || limit_vr->type == VR_VARYING
826 || symbolic_range_p (limit_vr)))
829 /* Special handling for integral types with super-types. Some FEs
830 construct integral types derived from other types and restrict
831 the range of values these new types may take.
833 It may happen that LIMIT is actually smaller than TYPE's minimum
834 value. For instance, the Ada FE is generating code like this
837 D.1480_32 = nam_30 - 300000361;
838 if (D.1480_32 <= 1) goto <L112>; else goto <L52>;
840 D.1480_94 = ASSERT_EXPR <D.1480_32, D.1480_32 <= 1>;
842 All the names are of type types__name_id___XDLU_300000000__399999999
843 which has min == 300000000 and max == 399999999. This means that
844 the ASSERT_EXPR would try to create the range [3000000, 1] which
847 The fact that the type specifies MIN and MAX values does not
848 automatically mean that every variable of that type will always
849 be within that range, so the predicate may well be true at run
850 time. If we had symbolic -INF and +INF values, we could
851 represent this range, but we currently represent -INF and +INF
852 using the type's min and max values.
854 So, the only sensible thing we can do for now is set the
855 resulting range to VR_VARYING. TODO, would having symbolic -INF
856 and +INF values be worth the trouble? */
857 if (TREE_CODE (limit) != SSA_NAME
858 && INTEGRAL_TYPE_P (type)
861 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
863 tree type_min = TYPE_MIN_VALUE (type);
864 int cmp = compare_values (limit, type_min);
866 /* For < or <= comparisons, if LIMIT is smaller than
867 TYPE_MIN, set the range to VR_VARYING. */
868 if (cmp == -1 || cmp == 0)
870 set_value_range_to_varying (vr_p);
874 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
876 tree type_max = TYPE_MIN_VALUE (type);
877 int cmp = compare_values (limit, type_max);
879 /* For > or >= comparisons, if LIMIT is bigger than
880 TYPE_MAX, set the range to VR_VARYING. */
881 if (cmp == 1 || cmp == 0)
883 set_value_range_to_varying (vr_p);
889 /* Initially, the new range has the same set of equivalences of
890 VAR's range. This will be revised before returning the final
891 value. Since assertions may be chained via mutually exclusive
892 predicates, we will need to trim the set of equivalences before
894 gcc_assert (vr_p->equiv == NULL);
895 vr_p->equiv = BITMAP_ALLOC (NULL);
896 add_equivalence (vr_p->equiv, var);
898 /* Extract a new range based on the asserted comparison for VAR and
899 LIMIT's value range. Notice that if LIMIT has an anti-range, we
900 will only use it for equality comparisons (EQ_EXPR). For any
901 other kind of assertion, we cannot derive a range from LIMIT's
902 anti-range that can be used to describe the new range. For
903 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
904 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
905 no single range for x_2 that could describe LE_EXPR, so we might
906 as well build the range [b_4, +INF] for it. */
907 if (cond_code == EQ_EXPR)
909 enum value_range_type range_type;
913 range_type = limit_vr->type;
919 range_type = VR_RANGE;
924 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
926 /* When asserting the equality VAR == LIMIT and LIMIT is another
927 SSA name, the new range will also inherit the equivalence set
929 if (TREE_CODE (limit) == SSA_NAME)
930 add_equivalence (vr_p->equiv, limit);
932 else if (cond_code == NE_EXPR)
934 /* As described above, when LIMIT's range is an anti-range and
935 this assertion is an inequality (NE_EXPR), then we cannot
936 derive anything from the anti-range. For instance, if
937 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
938 not imply that VAR's range is [0, 0]. So, in the case of
939 anti-ranges, we just assert the inequality using LIMIT and
942 If LIMIT_VR is a range, we can only use it to build a new
943 anti-range if LIMIT_VR is a single-valued range. For
944 instance, if LIMIT_VR is [0, 1], the predicate
945 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
946 Rather, it means that for value 0 VAR should be ~[0, 0]
947 and for value 1, VAR should be ~[1, 1]. We cannot
948 represent these ranges.
950 The only situation in which we can build a valid
951 anti-range is when LIMIT_VR is a single-valued range
952 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
953 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
955 && limit_vr->type == VR_RANGE
956 && compare_values (limit_vr->min, limit_vr->max) == 0)
963 /* In any other case, we cannot use LIMIT's range to build a
968 /* If MIN and MAX cover the whole range for their type, then
969 just use the original LIMIT. */
970 if (INTEGRAL_TYPE_P (type)
971 && min == TYPE_MIN_VALUE (type)
972 && max == TYPE_MAX_VALUE (type))
975 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
977 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
979 min = TYPE_MIN_VALUE (type);
981 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
985 /* If LIMIT_VR is of the form [N1, N2], we need to build the
986 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
991 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
992 if (cond_code == LT_EXPR)
994 tree one = build_int_cst (type, 1);
995 max = fold_build2 (MINUS_EXPR, type, max, one);
998 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1000 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
1002 max = TYPE_MAX_VALUE (type);
1004 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
1008 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1009 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
1011 min = limit_vr->min;
1014 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
1015 if (cond_code == GT_EXPR)
1017 tree one = build_int_cst (type, 1);
1018 min = fold_build2 (PLUS_EXPR, type, min, one);
1021 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1026 /* If VAR already had a known range, it may happen that the new
1027 range we have computed and VAR's range are not compatible. For
1031 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
1033 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
1035 While the above comes from a faulty program, it will cause an ICE
1036 later because p_8 and p_6 will have incompatible ranges and at
1037 the same time will be considered equivalent. A similar situation
1041 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
1043 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
1045 Again i_6 and i_7 will have incompatible ranges. It would be
1046 pointless to try and do anything with i_7's range because
1047 anything dominated by 'if (i_5 < 5)' will be optimized away.
1048 Note, due to the wa in which simulation proceeds, the statement
1049 i_7 = ASSERT_EXPR <...> we would never be visited because the
1050 conditional 'if (i_5 < 5)' always evaluates to false. However,
1051 this extra check does not hurt and may protect against future
1052 changes to VRP that may get into a situation similar to the
1053 NULL pointer dereference example.
1055 Note that these compatibility tests are only needed when dealing
1056 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1057 are both anti-ranges, they will always be compatible, because two
1058 anti-ranges will always have a non-empty intersection. */
1060 var_vr = get_value_range (var);
1062 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1063 ranges or anti-ranges. */
1064 if (vr_p->type == VR_VARYING
1065 || vr_p->type == VR_UNDEFINED
1066 || var_vr->type == VR_VARYING
1067 || var_vr->type == VR_UNDEFINED
1068 || symbolic_range_p (vr_p)
1069 || symbolic_range_p (var_vr))
1072 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
1074 /* If the two ranges have a non-empty intersection, we can
1075 refine the resulting range. Since the assert expression
1076 creates an equivalency and at the same time it asserts a
1077 predicate, we can take the intersection of the two ranges to
1078 get better precision. */
1079 if (value_ranges_intersect_p (var_vr, vr_p))
1081 /* Use the larger of the two minimums. */
1082 if (compare_values (vr_p->min, var_vr->min) == -1)
1087 /* Use the smaller of the two maximums. */
1088 if (compare_values (vr_p->max, var_vr->max) == 1)
1093 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
1097 /* The two ranges do not intersect, set the new range to
1098 VARYING, because we will not be able to do anything
1099 meaningful with it. */
1100 set_value_range_to_varying (vr_p);
1103 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
1104 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
1106 /* A range and an anti-range will cancel each other only if
1107 their ends are the same. For instance, in the example above,
1108 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1109 so VR_P should be set to VR_VARYING. */
1110 if (compare_values (var_vr->min, vr_p->min) == 0
1111 && compare_values (var_vr->max, vr_p->max) == 0)
1112 set_value_range_to_varying (vr_p);
1115 tree min, max, anti_min, anti_max, real_min, real_max;
1117 /* We want to compute the logical AND of the two ranges;
1118 there are three cases to consider.
1121 1. The VR_ANTI_RANGE range is competely within the
1122 VR_RANGE and the endpoints of the ranges are
1123 different. In that case the resulting range
1124 should be whichever range is more precise.
1125 Typically that will be the VR_RANGE.
1127 2. The VR_ANTI_RANGE is completely disjoint from
1128 the VR_RANGE. In this case the resulting range
1129 should be the VR_RANGE.
1131 3. There is some overlap between the VR_ANTI_RANGE
1134 3a. If the high limit of the VR_ANTI_RANGE resides
1135 within the VR_RANGE, then the result is a new
1136 VR_RANGE starting at the high limit of the
1137 the VR_ANTI_RANGE + 1 and extending to the
1138 high limit of the original VR_RANGE.
1140 3b. If the low limit of the VR_ANTI_RANGE resides
1141 within the VR_RANGE, then the result is a new
1142 VR_RANGE starting at the low limit of the original
1143 VR_RANGE and extending to the low limit of the
1144 VR_ANTI_RANGE - 1. */
1145 if (vr_p->type == VR_ANTI_RANGE)
1147 anti_min = vr_p->min;
1148 anti_max = vr_p->max;
1149 real_min = var_vr->min;
1150 real_max = var_vr->max;
1154 anti_min = var_vr->min;
1155 anti_max = var_vr->max;
1156 real_min = vr_p->min;
1157 real_max = vr_p->max;
1161 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1162 not including any endpoints. */
1163 if (compare_values (anti_max, real_max) == -1
1164 && compare_values (anti_min, real_min) == 1)
1166 set_value_range (vr_p, VR_RANGE, real_min,
1167 real_max, vr_p->equiv);
1169 /* Case 2, VR_ANTI_RANGE completely disjoint from
1171 else if (compare_values (anti_min, real_max) == 1
1172 || compare_values (anti_max, real_min) == -1)
1174 set_value_range (vr_p, VR_RANGE, real_min,
1175 real_max, vr_p->equiv);
1177 /* Case 3a, the anti-range extends into the low
1178 part of the real range. Thus creating a new
1179 low for the real reange. */
1180 else if ((compare_values (anti_max, real_min) == 1
1181 || compare_values (anti_max, real_min) == 0)
1182 && compare_values (anti_max, real_max) == -1)
1184 min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min),
1186 build_int_cst (TREE_TYPE (var_vr->min), 1));
1188 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1190 /* Case 3b, the anti-range extends into the high
1191 part of the real range. Thus creating a new
1192 higher for the real reange. */
1193 else if (compare_values (anti_min, real_min) == 1
1194 && (compare_values (anti_min, real_max) == -1
1195 || compare_values (anti_min, real_max) == 0))
1197 max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min),
1199 build_int_cst (TREE_TYPE (var_vr->min), 1));
1201 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1206 /* Remove names from the equivalence set that have ranges
1207 incompatible with VR_P. */
1209 fix_equivalence_set (vr_p);
1213 /* Extract range information from SSA name VAR and store it in VR. If
1214 VAR has an interesting range, use it. Otherwise, create the
1215 range [VAR, VAR] and return it. This is useful in situations where
1216 we may have conditionals testing values of VARYING names. For
1223 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1227 extract_range_from_ssa_name (value_range_t *vr, tree var)
1229 value_range_t *var_vr = get_value_range (var);
1231 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
1232 copy_value_range (vr, var_vr);
1234 set_value_range (vr, VR_RANGE, var, var, NULL);
1236 add_equivalence (vr->equiv, var);
1240 /* Wrapper around int_const_binop. If the operation overflows and we
1241 are not using wrapping arithmetic, then adjust the result to be
1242 -INF or +INF depending on CODE, VAL1 and VAL2. */
1245 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
1250 return int_const_binop (code, val1, val2, 0);
1252 /* If we are not using wrapping arithmetic, operate symbolically
1253 on -INF and +INF. */
1254 res = int_const_binop (code, val1, val2, 0);
1256 if (TYPE_UNSIGNED (TREE_TYPE (val1)))
1258 int checkz = compare_values (res, val1);
1260 /* Ensure that res = val1 [+*] val2 >= val1
1261 or that res = val1 - val2 <= val1. */
1262 if (((code == PLUS_EXPR || code == MULT_EXPR)
1263 && !(checkz == 1 || checkz == 0))
1264 || (code == MINUS_EXPR
1265 && !(checkz == 0 || checkz == -1)))
1267 res = copy_node (res);
1268 TREE_OVERFLOW (res) = 1;
1271 else if (TREE_OVERFLOW (res)
1272 && !TREE_OVERFLOW (val1)
1273 && !TREE_OVERFLOW (val2))
1275 /* If the operation overflowed but neither VAL1 nor VAL2 are
1276 overflown, return -INF or +INF depending on the operation
1277 and the combination of signs of the operands. */
1278 int sgn1 = tree_int_cst_sgn (val1);
1279 int sgn2 = tree_int_cst_sgn (val2);
1281 /* Notice that we only need to handle the restricted set of
1282 operations handled by extract_range_from_binary_expr.
1283 Among them, only multiplication, addition and subtraction
1284 can yield overflow without overflown operands because we
1285 are working with integral types only... except in the
1286 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1287 for division too. */
1289 /* For multiplication, the sign of the overflow is given
1290 by the comparison of the signs of the operands. */
1291 if ((code == MULT_EXPR && sgn1 == sgn2)
1292 /* For addition, the operands must be of the same sign
1293 to yield an overflow. Its sign is therefore that
1294 of one of the operands, for example the first. */
1295 || (code == PLUS_EXPR && sgn1 > 0)
1296 /* For subtraction, the operands must be of different
1297 signs to yield an overflow. Its sign is therefore
1298 that of the first operand or the opposite of that
1299 of the second operand. A first operand of 0 counts
1300 as positive here, for the corner case 0 - (-INF),
1301 which overflows, but must yield +INF. */
1302 || (code == MINUS_EXPR && sgn1 >= 0)
1303 /* For division, the only case is -INF / -1 = +INF. */
1304 || code == TRUNC_DIV_EXPR
1305 || code == FLOOR_DIV_EXPR
1306 || code == CEIL_DIV_EXPR
1307 || code == EXACT_DIV_EXPR
1308 || code == ROUND_DIV_EXPR)
1309 return TYPE_MAX_VALUE (TREE_TYPE (res));
1311 return TYPE_MIN_VALUE (TREE_TYPE (res));
1318 /* Extract range information from a binary expression EXPR based on
1319 the ranges of each of its operands and the expression code. */
1322 extract_range_from_binary_expr (value_range_t *vr, tree expr)
1324 enum tree_code code = TREE_CODE (expr);
1325 enum value_range_type type;
1326 tree op0, op1, min, max;
1328 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1329 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1331 /* Not all binary expressions can be applied to ranges in a
1332 meaningful way. Handle only arithmetic operations. */
1333 if (code != PLUS_EXPR
1334 && code != MINUS_EXPR
1335 && code != MULT_EXPR
1336 && code != TRUNC_DIV_EXPR
1337 && code != FLOOR_DIV_EXPR
1338 && code != CEIL_DIV_EXPR
1339 && code != EXACT_DIV_EXPR
1340 && code != ROUND_DIV_EXPR
1343 && code != BIT_AND_EXPR
1344 && code != TRUTH_ANDIF_EXPR
1345 && code != TRUTH_ORIF_EXPR
1346 && code != TRUTH_AND_EXPR
1347 && code != TRUTH_OR_EXPR)
1349 set_value_range_to_varying (vr);
1353 /* Get value ranges for each operand. For constant operands, create
1354 a new value range with the operand to simplify processing. */
1355 op0 = TREE_OPERAND (expr, 0);
1356 if (TREE_CODE (op0) == SSA_NAME)
1357 vr0 = *(get_value_range (op0));
1358 else if (is_gimple_min_invariant (op0))
1359 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1361 set_value_range_to_varying (&vr0);
1363 op1 = TREE_OPERAND (expr, 1);
1364 if (TREE_CODE (op1) == SSA_NAME)
1365 vr1 = *(get_value_range (op1));
1366 else if (is_gimple_min_invariant (op1))
1367 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1369 set_value_range_to_varying (&vr1);
1371 /* If either range is UNDEFINED, so is the result. */
1372 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1374 set_value_range_to_undefined (vr);
1378 /* The type of the resulting value range defaults to VR0.TYPE. */
1381 /* Refuse to operate on VARYING ranges, ranges of different kinds
1382 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1383 because we may be able to derive a useful range even if one of
1384 the operands is VR_VARYING or symbolic range. TODO, we may be
1385 able to derive anti-ranges in some cases. */
1386 if (code != BIT_AND_EXPR
1387 && code != TRUTH_AND_EXPR
1388 && code != TRUTH_OR_EXPR
1389 && (vr0.type == VR_VARYING
1390 || vr1.type == VR_VARYING
1391 || vr0.type != vr1.type
1392 || symbolic_range_p (&vr0)
1393 || symbolic_range_p (&vr1)))
1395 set_value_range_to_varying (vr);
1399 /* Now evaluate the expression to determine the new range. */
1400 if (POINTER_TYPE_P (TREE_TYPE (expr))
1401 || POINTER_TYPE_P (TREE_TYPE (op0))
1402 || POINTER_TYPE_P (TREE_TYPE (op1)))
1404 /* For pointer types, we are really only interested in asserting
1405 whether the expression evaluates to non-NULL. FIXME, we used
1406 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1407 ivopts is generating expressions with pointer multiplication
1409 if (code == PLUS_EXPR)
1411 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1412 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1413 else if (range_is_null (&vr0) && range_is_null (&vr1))
1414 set_value_range_to_null (vr, TREE_TYPE (expr));
1416 set_value_range_to_varying (vr);
1420 /* Subtracting from a pointer, may yield 0, so just drop the
1421 resulting range to varying. */
1422 set_value_range_to_varying (vr);
1428 /* For integer ranges, apply the operation to each end of the
1429 range and see what we end up with. */
1430 if (code == TRUTH_ANDIF_EXPR
1431 || code == TRUTH_ORIF_EXPR
1432 || code == TRUTH_AND_EXPR
1433 || code == TRUTH_OR_EXPR)
1435 /* If one of the operands is zero, we know that the whole
1436 expression evaluates zero. */
1437 if (code == TRUTH_AND_EXPR
1438 && ((vr0.type == VR_RANGE
1439 && integer_zerop (vr0.min)
1440 && integer_zerop (vr0.max))
1441 || (vr1.type == VR_RANGE
1442 && integer_zerop (vr1.min)
1443 && integer_zerop (vr1.max))))
1446 min = max = build_int_cst (TREE_TYPE (expr), 0);
1448 /* If one of the operands is one, we know that the whole
1449 expression evaluates one. */
1450 else if (code == TRUTH_OR_EXPR
1451 && ((vr0.type == VR_RANGE
1452 && integer_onep (vr0.min)
1453 && integer_onep (vr0.max))
1454 || (vr1.type == VR_RANGE
1455 && integer_onep (vr1.min)
1456 && integer_onep (vr1.max))))
1459 min = max = build_int_cst (TREE_TYPE (expr), 1);
1461 else if (vr0.type != VR_VARYING
1462 && vr1.type != VR_VARYING
1463 && vr0.type == vr1.type
1464 && !symbolic_range_p (&vr0)
1465 && !symbolic_range_p (&vr1))
1467 /* Boolean expressions cannot be folded with int_const_binop. */
1468 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1469 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1473 set_value_range_to_varying (vr);
1477 else if (code == PLUS_EXPR
1479 || code == MAX_EXPR)
1481 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1482 VR_VARYING. It would take more effort to compute a precise
1483 range for such a case. For example, if we have op0 == 1 and
1484 op1 == -1 with their ranges both being ~[0,0], we would have
1485 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1486 Note that we are guaranteed to have vr0.type == vr1.type at
1488 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1490 set_value_range_to_varying (vr);
1494 /* For operations that make the resulting range directly
1495 proportional to the original ranges, apply the operation to
1496 the same end of each range. */
1497 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1498 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1500 else if (code == MULT_EXPR
1501 || code == TRUNC_DIV_EXPR
1502 || code == FLOOR_DIV_EXPR
1503 || code == CEIL_DIV_EXPR
1504 || code == EXACT_DIV_EXPR
1505 || code == ROUND_DIV_EXPR)
1510 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1511 drop to VR_VARYING. It would take more effort to compute a
1512 precise range for such a case. For example, if we have
1513 op0 == 65536 and op1 == 65536 with their ranges both being
1514 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1515 we cannot claim that the product is in ~[0,0]. Note that we
1516 are guaranteed to have vr0.type == vr1.type at this
1518 if (code == MULT_EXPR
1519 && vr0.type == VR_ANTI_RANGE
1520 && (flag_wrapv || TYPE_UNSIGNED (TREE_TYPE (op0))))
1522 set_value_range_to_varying (vr);
1526 /* Multiplications and divisions are a bit tricky to handle,
1527 depending on the mix of signs we have in the two ranges, we
1528 need to operate on different values to get the minimum and
1529 maximum values for the new range. One approach is to figure
1530 out all the variations of range combinations and do the
1533 However, this involves several calls to compare_values and it
1534 is pretty convoluted. It's simpler to do the 4 operations
1535 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1536 MAX1) and then figure the smallest and largest values to form
1539 /* Divisions by zero result in a VARYING value. */
1540 if (code != MULT_EXPR
1541 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1543 set_value_range_to_varying (vr);
1547 /* Compute the 4 cross operations. */
1548 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1550 val[1] = (vr1.max != vr1.min)
1551 ? vrp_int_const_binop (code, vr0.min, vr1.max)
1554 val[2] = (vr0.max != vr0.min)
1555 ? vrp_int_const_binop (code, vr0.max, vr1.min)
1558 val[3] = (vr0.min != vr0.max && vr1.min != vr1.max)
1559 ? vrp_int_const_binop (code, vr0.max, vr1.max)
1562 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1566 for (i = 1; i < 4; i++)
1568 if (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
1569 || !is_gimple_min_invariant (max) || TREE_OVERFLOW (max))
1574 if (!is_gimple_min_invariant (val[i]) || TREE_OVERFLOW (val[i]))
1576 /* If we found an overflowed value, set MIN and MAX
1577 to it so that we set the resulting range to
1583 if (compare_values (val[i], min) == -1)
1586 if (compare_values (val[i], max) == 1)
1591 else if (code == MINUS_EXPR)
1593 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1594 VR_VARYING. It would take more effort to compute a precise
1595 range for such a case. For example, if we have op0 == 1 and
1596 op1 == 1 with their ranges both being ~[0,0], we would have
1597 op0 - op1 == 0, so we cannot claim that the difference is in
1598 ~[0,0]. Note that we are guaranteed to have
1599 vr0.type == vr1.type at this point. */
1600 if (vr0.type == VR_ANTI_RANGE)
1602 set_value_range_to_varying (vr);
1606 /* For MINUS_EXPR, apply the operation to the opposite ends of
1608 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1609 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1611 else if (code == BIT_AND_EXPR)
1613 if (vr0.type == VR_RANGE
1614 && vr0.min == vr0.max
1615 && tree_expr_nonnegative_p (vr0.max)
1616 && TREE_CODE (vr0.max) == INTEGER_CST)
1618 min = build_int_cst (TREE_TYPE (expr), 0);
1621 else if (vr1.type == VR_RANGE
1622 && vr1.min == vr1.max
1623 && tree_expr_nonnegative_p (vr1.max)
1624 && TREE_CODE (vr1.max) == INTEGER_CST)
1627 min = build_int_cst (TREE_TYPE (expr), 0);
1632 set_value_range_to_varying (vr);
1639 /* If either MIN or MAX overflowed, then set the resulting range to
1641 if (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
1642 || !is_gimple_min_invariant (max) || TREE_OVERFLOW (max))
1644 set_value_range_to_varying (vr);
1648 cmp = compare_values (min, max);
1649 if (cmp == -2 || cmp == 1)
1651 /* If the new range has its limits swapped around (MIN > MAX),
1652 then the operation caused one of them to wrap around, mark
1653 the new range VARYING. */
1654 set_value_range_to_varying (vr);
1657 set_value_range (vr, type, min, max, NULL);
1661 /* Extract range information from a unary expression EXPR based on
1662 the range of its operand and the expression code. */
1665 extract_range_from_unary_expr (value_range_t *vr, tree expr)
1667 enum tree_code code = TREE_CODE (expr);
1670 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1672 /* Refuse to operate on certain unary expressions for which we
1673 cannot easily determine a resulting range. */
1674 if (code == FIX_TRUNC_EXPR
1675 || code == FIX_CEIL_EXPR
1676 || code == FIX_FLOOR_EXPR
1677 || code == FIX_ROUND_EXPR
1678 || code == FLOAT_EXPR
1679 || code == BIT_NOT_EXPR
1680 || code == NON_LVALUE_EXPR
1681 || code == CONJ_EXPR)
1683 set_value_range_to_varying (vr);
1687 /* Get value ranges for the operand. For constant operands, create
1688 a new value range with the operand to simplify processing. */
1689 op0 = TREE_OPERAND (expr, 0);
1690 if (TREE_CODE (op0) == SSA_NAME)
1691 vr0 = *(get_value_range (op0));
1692 else if (is_gimple_min_invariant (op0))
1693 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1695 set_value_range_to_varying (&vr0);
1697 /* If VR0 is UNDEFINED, so is the result. */
1698 if (vr0.type == VR_UNDEFINED)
1700 set_value_range_to_undefined (vr);
1704 /* Refuse to operate on varying and symbolic ranges. Also, if the
1705 operand is neither a pointer nor an integral type, set the
1706 resulting range to VARYING. TODO, in some cases we may be able
1707 to derive anti-ranges (like nonzero values). */
1708 if (vr0.type == VR_VARYING
1709 || (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
1710 && !POINTER_TYPE_P (TREE_TYPE (op0)))
1711 || symbolic_range_p (&vr0))
1713 set_value_range_to_varying (vr);
1717 /* If the expression involves pointers, we are only interested in
1718 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1719 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
1721 if (range_is_nonnull (&vr0) || tree_expr_nonzero_p (expr))
1722 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1723 else if (range_is_null (&vr0))
1724 set_value_range_to_null (vr, TREE_TYPE (expr));
1726 set_value_range_to_varying (vr);
1731 /* Handle unary expressions on integer ranges. */
1732 if (code == NOP_EXPR || code == CONVERT_EXPR)
1734 tree inner_type = TREE_TYPE (op0);
1735 tree outer_type = TREE_TYPE (expr);
1737 /* If VR0 represents a simple range, then try to convert
1738 the min and max values for the range to the same type
1739 as OUTER_TYPE. If the results compare equal to VR0's
1740 min and max values and the new min is still less than
1741 or equal to the new max, then we can safely use the newly
1742 computed range for EXPR. This allows us to compute
1743 accurate ranges through many casts. */
1744 if (vr0.type == VR_RANGE)
1746 tree new_min, new_max;
1748 /* Convert VR0's min/max to OUTER_TYPE. */
1749 new_min = fold_convert (outer_type, vr0.min);
1750 new_max = fold_convert (outer_type, vr0.max);
1752 /* Verify the new min/max values are gimple values and
1753 that they compare equal to VR0's min/max values. */
1754 if (is_gimple_val (new_min)
1755 && is_gimple_val (new_max)
1756 && tree_int_cst_equal (new_min, vr0.min)
1757 && tree_int_cst_equal (new_max, vr0.max)
1758 && compare_values (new_min, new_max) <= 0
1759 && compare_values (new_min, new_max) >= -1)
1761 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
1766 /* When converting types of different sizes, set the result to
1767 VARYING. Things like sign extensions and precision loss may
1768 change the range. For instance, if x_3 is of type 'long long
1769 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1770 is impossible to know at compile time whether y_5 will be
1772 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
1773 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
1775 set_value_range_to_varying (vr);
1780 /* Apply the operation to each end of the range and see what we end
1782 if (code == NEGATE_EXPR
1783 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1785 /* NEGATE_EXPR flips the range around. */
1786 min = (vr0.max == TYPE_MAX_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
1787 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1788 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1790 max = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
1791 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1792 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1795 else if (code == NEGATE_EXPR
1796 && TYPE_UNSIGNED (TREE_TYPE (expr)))
1798 if (!range_includes_zero_p (&vr0))
1800 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1801 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1805 if (range_is_null (&vr0))
1806 set_value_range_to_null (vr, TREE_TYPE (expr));
1808 set_value_range_to_varying (vr);
1812 else if (code == ABS_EXPR
1813 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1815 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1818 && ((vr0.type == VR_RANGE
1819 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1820 || (vr0.type == VR_ANTI_RANGE
1821 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
1822 && !range_includes_zero_p (&vr0))))
1824 set_value_range_to_varying (vr);
1828 /* ABS_EXPR may flip the range around, if the original range
1829 included negative values. */
1830 min = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1831 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1832 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1834 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1836 cmp = compare_values (min, max);
1838 /* If a VR_ANTI_RANGEs contains zero, then we have
1839 ~[-INF, min(MIN, MAX)]. */
1840 if (vr0.type == VR_ANTI_RANGE)
1842 if (range_includes_zero_p (&vr0))
1844 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
1846 /* Take the lower of the two values. */
1850 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1851 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1852 flag_wrapv is set and the original anti-range doesn't include
1853 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1854 min = (flag_wrapv && vr0.min != type_min_value
1855 ? int_const_binop (PLUS_EXPR,
1857 integer_one_node, 0)
1862 /* All else has failed, so create the range [0, INF], even for
1863 flag_wrapv since TYPE_MIN_VALUE is in the original
1865 vr0.type = VR_RANGE;
1866 min = build_int_cst (TREE_TYPE (expr), 0);
1867 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
1871 /* If the range contains zero then we know that the minimum value in the
1872 range will be zero. */
1873 else if (range_includes_zero_p (&vr0))
1877 min = build_int_cst (TREE_TYPE (expr), 0);
1881 /* If the range was reversed, swap MIN and MAX. */
1892 /* Otherwise, operate on each end of the range. */
1893 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1894 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1897 cmp = compare_values (min, max);
1898 if (cmp == -2 || cmp == 1)
1900 /* If the new range has its limits swapped around (MIN > MAX),
1901 then the operation caused one of them to wrap around, mark
1902 the new range VARYING. */
1903 set_value_range_to_varying (vr);
1906 set_value_range (vr, vr0.type, min, max, NULL);
1910 /* Extract range information from a comparison expression EXPR based
1911 on the range of its operand and the expression code. */
1914 extract_range_from_comparison (value_range_t *vr, tree expr)
1916 tree val = vrp_evaluate_conditional (expr, false);
1919 /* Since this expression was found on the RHS of an assignment,
1920 its type may be different from _Bool. Convert VAL to EXPR's
1922 val = fold_convert (TREE_TYPE (expr), val);
1923 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
1926 set_value_range_to_varying (vr);
1930 /* Try to compute a useful range out of expression EXPR and store it
1934 extract_range_from_expr (value_range_t *vr, tree expr)
1936 enum tree_code code = TREE_CODE (expr);
1938 if (code == ASSERT_EXPR)
1939 extract_range_from_assert (vr, expr);
1940 else if (code == SSA_NAME)
1941 extract_range_from_ssa_name (vr, expr);
1942 else if (TREE_CODE_CLASS (code) == tcc_binary
1943 || code == TRUTH_ANDIF_EXPR
1944 || code == TRUTH_ORIF_EXPR
1945 || code == TRUTH_AND_EXPR
1946 || code == TRUTH_OR_EXPR
1947 || code == TRUTH_XOR_EXPR)
1948 extract_range_from_binary_expr (vr, expr);
1949 else if (TREE_CODE_CLASS (code) == tcc_unary)
1950 extract_range_from_unary_expr (vr, expr);
1951 else if (TREE_CODE_CLASS (code) == tcc_comparison)
1952 extract_range_from_comparison (vr, expr);
1953 else if (is_gimple_min_invariant (expr))
1954 set_value_range (vr, VR_RANGE, expr, expr, NULL);
1956 set_value_range_to_varying (vr);
1958 /* If we got a varying range from the tests above, try a final
1959 time to derive a nonnegative or nonzero range. This time
1960 relying primarily on generic routines in fold in conjunction
1962 if (vr->type == VR_VARYING)
1964 if (INTEGRAL_TYPE_P (TREE_TYPE (expr))
1965 && vrp_expr_computes_nonnegative (expr))
1966 set_value_range_to_nonnegative (vr, TREE_TYPE (expr));
1967 else if (vrp_expr_computes_nonzero (expr))
1968 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1972 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1973 would be profitable to adjust VR using scalar evolution information
1974 for VAR. If so, update VR with the new limits. */
1977 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
1980 tree init, step, chrec;
1981 bool init_is_max, unknown_max;
1983 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1984 better opportunities than a regular range, but I'm not sure. */
1985 if (vr->type == VR_ANTI_RANGE)
1988 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
1989 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
1992 init = initial_condition_in_loop_num (chrec, loop->num);
1993 step = evolution_part_in_loop_num (chrec, loop->num);
1995 /* If STEP is symbolic, we can't know whether INIT will be the
1996 minimum or maximum value in the range. */
1997 if (step == NULL_TREE
1998 || !is_gimple_min_invariant (step))
2001 /* Do not adjust ranges when chrec may wrap. */
2002 if (scev_probably_wraps_p (chrec_type (chrec), init, step, stmt,
2003 current_loops->parray[CHREC_VARIABLE (chrec)],
2004 &init_is_max, &unknown_max)
2008 if (!POINTER_TYPE_P (TREE_TYPE (init))
2009 && (vr->type == VR_VARYING || vr->type == VR_UNDEFINED))
2011 /* For VARYING or UNDEFINED ranges, just about anything we get
2012 from scalar evolutions should be better. */
2013 tree min = TYPE_MIN_VALUE (TREE_TYPE (init));
2014 tree max = TYPE_MAX_VALUE (TREE_TYPE (init));
2021 /* If we would create an invalid range, then just assume we
2022 know absolutely nothing. This may be over-conservative,
2023 but it's clearly safe. */
2024 if (compare_values (min, max) == 1)
2027 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2029 else if (vr->type == VR_RANGE)
2036 /* INIT is the maximum value. If INIT is lower than VR->MAX
2037 but no smaller than VR->MIN, set VR->MAX to INIT. */
2038 if (compare_values (init, max) == -1)
2042 /* If we just created an invalid range with the minimum
2043 greater than the maximum, take the minimum all the
2045 if (compare_values (min, max) == 1)
2046 min = TYPE_MIN_VALUE (TREE_TYPE (min));
2051 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2052 if (compare_values (init, min) == 1)
2056 /* If we just created an invalid range with the minimum
2057 greater than the maximum, take the maximum all the
2059 if (compare_values (min, max) == 1)
2060 max = TYPE_MAX_VALUE (TREE_TYPE (max));
2064 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2069 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2071 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2072 all the values in the ranges.
2074 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2076 - Return NULL_TREE if it is not always possible to determine the
2077 value of the comparison. */
2081 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1)
2083 /* VARYING or UNDEFINED ranges cannot be compared. */
2084 if (vr0->type == VR_VARYING
2085 || vr0->type == VR_UNDEFINED
2086 || vr1->type == VR_VARYING
2087 || vr1->type == VR_UNDEFINED)
2090 /* Anti-ranges need to be handled separately. */
2091 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
2093 /* If both are anti-ranges, then we cannot compute any
2095 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
2098 /* These comparisons are never statically computable. */
2105 /* Equality can be computed only between a range and an
2106 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2107 if (vr0->type == VR_RANGE)
2109 /* To simplify processing, make VR0 the anti-range. */
2110 value_range_t *tmp = vr0;
2115 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
2117 if (compare_values (vr0->min, vr1->min) == 0
2118 && compare_values (vr0->max, vr1->max) == 0)
2119 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2124 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2125 operands around and change the comparison code. */
2126 if (comp == GT_EXPR || comp == GE_EXPR)
2129 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
2135 if (comp == EQ_EXPR)
2137 /* Equality may only be computed if both ranges represent
2138 exactly one value. */
2139 if (compare_values (vr0->min, vr0->max) == 0
2140 && compare_values (vr1->min, vr1->max) == 0)
2142 int cmp_min = compare_values (vr0->min, vr1->min);
2143 int cmp_max = compare_values (vr0->max, vr1->max);
2144 if (cmp_min == 0 && cmp_max == 0)
2145 return boolean_true_node;
2146 else if (cmp_min != -2 && cmp_max != -2)
2147 return boolean_false_node;
2149 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2150 else if (compare_values (vr0->min, vr1->max) == 1
2151 || compare_values (vr1->min, vr0->max) == 1)
2152 return boolean_false_node;
2156 else if (comp == NE_EXPR)
2160 /* If VR0 is completely to the left or completely to the right
2161 of VR1, they are always different. Notice that we need to
2162 make sure that both comparisons yield similar results to
2163 avoid comparing values that cannot be compared at
2165 cmp1 = compare_values (vr0->max, vr1->min);
2166 cmp2 = compare_values (vr0->min, vr1->max);
2167 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
2168 return boolean_true_node;
2170 /* If VR0 and VR1 represent a single value and are identical,
2172 else if (compare_values (vr0->min, vr0->max) == 0
2173 && compare_values (vr1->min, vr1->max) == 0
2174 && compare_values (vr0->min, vr1->min) == 0
2175 && compare_values (vr0->max, vr1->max) == 0)
2176 return boolean_false_node;
2178 /* Otherwise, they may or may not be different. */
2182 else if (comp == LT_EXPR || comp == LE_EXPR)
2186 /* If VR0 is to the left of VR1, return true. */
2187 tst = compare_values (vr0->max, vr1->min);
2188 if ((comp == LT_EXPR && tst == -1)
2189 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2190 return boolean_true_node;
2192 /* If VR0 is to the right of VR1, return false. */
2193 tst = compare_values (vr0->min, vr1->max);
2194 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2195 || (comp == LE_EXPR && tst == 1))
2196 return boolean_false_node;
2198 /* Otherwise, we don't know. */
2206 /* Given a value range VR, a value VAL and a comparison code COMP, return
2207 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2208 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2209 always returns false. Return NULL_TREE if it is not always
2210 possible to determine the value of the comparison. */
2213 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val)
2215 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2218 /* Anti-ranges need to be handled separately. */
2219 if (vr->type == VR_ANTI_RANGE)
2221 /* For anti-ranges, the only predicates that we can compute at
2222 compile time are equality and inequality. */
2229 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2230 if (value_inside_range (val, vr) == 1)
2231 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2236 if (comp == EQ_EXPR)
2238 /* EQ_EXPR may only be computed if VR represents exactly
2240 if (compare_values (vr->min, vr->max) == 0)
2242 int cmp = compare_values (vr->min, val);
2244 return boolean_true_node;
2245 else if (cmp == -1 || cmp == 1 || cmp == 2)
2246 return boolean_false_node;
2248 else if (compare_values (val, vr->min) == -1
2249 || compare_values (vr->max, val) == -1)
2250 return boolean_false_node;
2254 else if (comp == NE_EXPR)
2256 /* If VAL is not inside VR, then they are always different. */
2257 if (compare_values (vr->max, val) == -1
2258 || compare_values (vr->min, val) == 1)
2259 return boolean_true_node;
2261 /* If VR represents exactly one value equal to VAL, then return
2263 if (compare_values (vr->min, vr->max) == 0
2264 && compare_values (vr->min, val) == 0)
2265 return boolean_false_node;
2267 /* Otherwise, they may or may not be different. */
2270 else if (comp == LT_EXPR || comp == LE_EXPR)
2274 /* If VR is to the left of VAL, return true. */
2275 tst = compare_values (vr->max, val);
2276 if ((comp == LT_EXPR && tst == -1)
2277 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2278 return boolean_true_node;
2280 /* If VR is to the right of VAL, return false. */
2281 tst = compare_values (vr->min, val);
2282 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2283 || (comp == LE_EXPR && tst == 1))
2284 return boolean_false_node;
2286 /* Otherwise, we don't know. */
2289 else if (comp == GT_EXPR || comp == GE_EXPR)
2293 /* If VR is to the right of VAL, return true. */
2294 tst = compare_values (vr->min, val);
2295 if ((comp == GT_EXPR && tst == 1)
2296 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
2297 return boolean_true_node;
2299 /* If VR is to the left of VAL, return false. */
2300 tst = compare_values (vr->max, val);
2301 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
2302 || (comp == GE_EXPR && tst == -1))
2303 return boolean_false_node;
2305 /* Otherwise, we don't know. */
2313 /* Debugging dumps. */
2315 void dump_value_range (FILE *, value_range_t *);
2316 void debug_value_range (value_range_t *);
2317 void dump_all_value_ranges (FILE *);
2318 void debug_all_value_ranges (void);
2319 void dump_vr_equiv (FILE *, bitmap);
2320 void debug_vr_equiv (bitmap);
2323 /* Dump value range VR to FILE. */
2326 dump_value_range (FILE *file, value_range_t *vr)
2329 fprintf (file, "[]");
2330 else if (vr->type == VR_UNDEFINED)
2331 fprintf (file, "UNDEFINED");
2332 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
2334 tree type = TREE_TYPE (vr->min);
2336 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
2338 if (INTEGRAL_TYPE_P (type)
2339 && !TYPE_UNSIGNED (type)
2340 && vr->min == TYPE_MIN_VALUE (type))
2341 fprintf (file, "-INF");
2343 print_generic_expr (file, vr->min, 0);
2345 fprintf (file, ", ");
2347 if (INTEGRAL_TYPE_P (type)
2348 && vr->max == TYPE_MAX_VALUE (type))
2349 fprintf (file, "+INF");
2351 print_generic_expr (file, vr->max, 0);
2353 fprintf (file, "]");
2360 fprintf (file, " EQUIVALENCES: { ");
2362 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
2364 print_generic_expr (file, ssa_name (i), 0);
2365 fprintf (file, " ");
2369 fprintf (file, "} (%u elements)", c);
2372 else if (vr->type == VR_VARYING)
2373 fprintf (file, "VARYING");
2375 fprintf (file, "INVALID RANGE");
2379 /* Dump value range VR to stderr. */
2382 debug_value_range (value_range_t *vr)
2384 dump_value_range (stderr, vr);
2388 /* Dump value ranges of all SSA_NAMEs to FILE. */
2391 dump_all_value_ranges (FILE *file)
2395 for (i = 0; i < num_ssa_names; i++)
2399 print_generic_expr (file, ssa_name (i), 0);
2400 fprintf (file, ": ");
2401 dump_value_range (file, vr_value[i]);
2402 fprintf (file, "\n");
2406 fprintf (file, "\n");
2410 /* Dump all value ranges to stderr. */
2413 debug_all_value_ranges (void)
2415 dump_all_value_ranges (stderr);
2419 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
2420 create a new SSA name N and return the assertion assignment
2421 'V = ASSERT_EXPR <V, V OP W>'. */
2424 build_assert_expr_for (tree cond, tree v)
2428 gcc_assert (TREE_CODE (v) == SSA_NAME);
2429 n = duplicate_ssa_name (v, NULL_TREE);
2431 if (COMPARISON_CLASS_P (cond))
2433 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
2434 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, a);
2436 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
2438 /* Given !V, build the assignment N = false. */
2439 tree op0 = TREE_OPERAND (cond, 0);
2440 gcc_assert (op0 == v);
2441 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_false_node);
2443 else if (TREE_CODE (cond) == SSA_NAME)
2445 /* Given V, build the assignment N = true. */
2446 gcc_assert (v == cond);
2447 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_true_node);
2452 SSA_NAME_DEF_STMT (n) = assertion;
2454 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
2455 operand of the ASSERT_EXPR. Register the new name and the old one
2456 in the replacement table so that we can fix the SSA web after
2457 adding all the ASSERT_EXPRs. */
2458 register_new_name_mapping (n, v);
2464 /* Return false if EXPR is a predicate expression involving floating
2468 fp_predicate (tree expr)
2470 return (COMPARISON_CLASS_P (expr)
2471 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
2475 /* If the range of values taken by OP can be inferred after STMT executes,
2476 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2477 describes the inferred range. Return true if a range could be
2481 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
2484 *comp_code_p = ERROR_MARK;
2486 /* Do not attempt to infer anything in names that flow through
2488 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
2491 /* Similarly, don't infer anything from statements that may throw
2493 if (tree_could_throw_p (stmt))
2496 /* If STMT is the last statement of a basic block with no
2497 successors, there is no point inferring anything about any of its
2498 operands. We would not be able to find a proper insertion point
2499 for the assertion, anyway. */
2500 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
2503 if (POINTER_TYPE_P (TREE_TYPE (op)))
2506 unsigned num_uses, num_derefs;
2508 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
2509 if (num_derefs > 0 && flag_delete_null_pointer_checks)
2511 /* We can only assume that a pointer dereference will yield
2512 non-NULL if -fdelete-null-pointer-checks is enabled. */
2513 *val_p = build_int_cst (TREE_TYPE (op), 0);
2514 *comp_code_p = NE_EXPR;
2523 void dump_asserts_for (FILE *, tree);
2524 void debug_asserts_for (tree);
2525 void dump_all_asserts (FILE *);
2526 void debug_all_asserts (void);
2528 /* Dump all the registered assertions for NAME to FILE. */
2531 dump_asserts_for (FILE *file, tree name)
2535 fprintf (file, "Assertions to be inserted for ");
2536 print_generic_expr (file, name, 0);
2537 fprintf (file, "\n");
2539 loc = asserts_for[SSA_NAME_VERSION (name)];
2542 fprintf (file, "\t");
2543 print_generic_expr (file, bsi_stmt (loc->si), 0);
2544 fprintf (file, "\n\tBB #%d", loc->bb->index);
2547 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
2548 loc->e->dest->index);
2549 dump_edge_info (file, loc->e, 0);
2551 fprintf (file, "\n\tPREDICATE: ");
2552 print_generic_expr (file, name, 0);
2553 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
2554 print_generic_expr (file, loc->val, 0);
2555 fprintf (file, "\n\n");
2559 fprintf (file, "\n");
2563 /* Dump all the registered assertions for NAME to stderr. */
2566 debug_asserts_for (tree name)
2568 dump_asserts_for (stderr, name);
2572 /* Dump all the registered assertions for all the names to FILE. */
2575 dump_all_asserts (FILE *file)
2580 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
2581 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2582 dump_asserts_for (file, ssa_name (i));
2583 fprintf (file, "\n");
2587 /* Dump all the registered assertions for all the names to stderr. */
2590 debug_all_asserts (void)
2592 dump_all_asserts (stderr);
2596 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2597 'NAME COMP_CODE VAL' at a location that dominates block BB or
2598 E->DEST, then register this location as a possible insertion point
2599 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2601 BB, E and SI provide the exact insertion point for the new
2602 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2603 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2604 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2605 must not be NULL. */
2608 register_new_assert_for (tree name,
2609 enum tree_code comp_code,
2613 block_stmt_iterator si)
2615 assert_locus_t n, loc, last_loc;
2617 basic_block dest_bb;
2619 #if defined ENABLE_CHECKING
2620 gcc_assert (bb == NULL || e == NULL);
2623 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
2624 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
2627 /* The new assertion A will be inserted at BB or E. We need to
2628 determine if the new location is dominated by a previously
2629 registered location for A. If we are doing an edge insertion,
2630 assume that A will be inserted at E->DEST. Note that this is not
2633 If E is a critical edge, it will be split. But even if E is
2634 split, the new block will dominate the same set of blocks that
2637 The reverse, however, is not true, blocks dominated by E->DEST
2638 will not be dominated by the new block created to split E. So,
2639 if the insertion location is on a critical edge, we will not use
2640 the new location to move another assertion previously registered
2641 at a block dominated by E->DEST. */
2642 dest_bb = (bb) ? bb : e->dest;
2644 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2645 VAL at a block dominating DEST_BB, then we don't need to insert a new
2646 one. Similarly, if the same assertion already exists at a block
2647 dominated by DEST_BB and the new location is not on a critical
2648 edge, then update the existing location for the assertion (i.e.,
2649 move the assertion up in the dominance tree).
2651 Note, this is implemented as a simple linked list because there
2652 should not be more than a handful of assertions registered per
2653 name. If this becomes a performance problem, a table hashed by
2654 COMP_CODE and VAL could be implemented. */
2655 loc = asserts_for[SSA_NAME_VERSION (name)];
2660 if (loc->comp_code == comp_code
2662 || operand_equal_p (loc->val, val, 0)))
2664 /* If the assertion NAME COMP_CODE VAL has already been
2665 registered at a basic block that dominates DEST_BB, then
2666 we don't need to insert the same assertion again. Note
2667 that we don't check strict dominance here to avoid
2668 replicating the same assertion inside the same basic
2669 block more than once (e.g., when a pointer is
2670 dereferenced several times inside a block).
2672 An exception to this rule are edge insertions. If the
2673 new assertion is to be inserted on edge E, then it will
2674 dominate all the other insertions that we may want to
2675 insert in DEST_BB. So, if we are doing an edge
2676 insertion, don't do this dominance check. */
2678 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
2681 /* Otherwise, if E is not a critical edge and DEST_BB
2682 dominates the existing location for the assertion, move
2683 the assertion up in the dominance tree by updating its
2684 location information. */
2685 if ((e == NULL || !EDGE_CRITICAL_P (e))
2686 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
2695 /* Update the last node of the list and move to the next one. */
2700 /* If we didn't find an assertion already registered for
2701 NAME COMP_CODE VAL, add a new one at the end of the list of
2702 assertions associated with NAME. */
2703 n = XNEW (struct assert_locus_d);
2707 n->comp_code = comp_code;
2714 asserts_for[SSA_NAME_VERSION (name)] = n;
2716 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
2720 /* Try to register an edge assertion for SSA name NAME on edge E for
2721 the conditional jump pointed to by SI. Return true if an assertion
2722 for NAME could be registered. */
2725 register_edge_assert_for (tree name, edge e, block_stmt_iterator si)
2728 enum tree_code comp_code;
2730 stmt = bsi_stmt (si);
2732 /* Do not attempt to infer anything in names that flow through
2734 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
2737 /* If NAME was not found in the sub-graph reachable from E, then
2738 there's nothing to do. */
2739 if (!TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
2742 /* We found a use of NAME in the sub-graph rooted at E->DEST.
2743 Register an assertion for NAME according to the value that NAME
2745 if (TREE_CODE (stmt) == COND_EXPR)
2747 /* If BB ends in a COND_EXPR then NAME then we should insert
2748 the original predicate on EDGE_TRUE_VALUE and the
2749 opposite predicate on EDGE_FALSE_VALUE. */
2750 tree cond = COND_EXPR_COND (stmt);
2751 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
2753 /* Predicates may be a single SSA name or NAME OP VAL. */
2756 /* If the predicate is a name, it must be NAME, in which
2757 case we create the predicate NAME == true or
2758 NAME == false accordingly. */
2759 comp_code = EQ_EXPR;
2760 val = (is_else_edge) ? boolean_false_node : boolean_true_node;
2764 /* Otherwise, we have a comparison of the form NAME COMP VAL
2765 or VAL COMP NAME. */
2766 if (name == TREE_OPERAND (cond, 1))
2768 /* If the predicate is of the form VAL COMP NAME, flip
2769 COMP around because we need to register NAME as the
2770 first operand in the predicate. */
2771 comp_code = swap_tree_comparison (TREE_CODE (cond));
2772 val = TREE_OPERAND (cond, 0);
2776 /* The comparison is of the form NAME COMP VAL, so the
2777 comparison code remains unchanged. */
2778 comp_code = TREE_CODE (cond);
2779 val = TREE_OPERAND (cond, 1);
2782 /* If we are inserting the assertion on the ELSE edge, we
2783 need to invert the sign comparison. */
2785 comp_code = invert_tree_comparison (comp_code, 0);
2787 /* Do not register always-false predicates. FIXME, this
2788 works around a limitation in fold() when dealing with
2789 enumerations. Given 'enum { N1, N2 } x;', fold will not
2790 fold 'if (x > N2)' to 'if (0)'. */
2791 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
2792 && (INTEGRAL_TYPE_P (TREE_TYPE (val))
2793 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (val))))
2795 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
2796 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
2798 if (comp_code == GT_EXPR && compare_values (val, max) == 0)
2801 if (comp_code == LT_EXPR && compare_values (val, min) == 0)
2808 /* FIXME. Handle SWITCH_EXPR. */
2812 register_new_assert_for (name, comp_code, val, NULL, e, si);
2817 static bool find_assert_locations (basic_block bb);
2819 /* Determine whether the outgoing edges of BB should receive an
2820 ASSERT_EXPR for each of the operands of BB's last statement. The
2821 last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2823 If any of the sub-graphs rooted at BB have an interesting use of
2824 the predicate operands, an assert location node is added to the
2825 list of assertions for the corresponding operands. */
2828 find_conditional_asserts (basic_block bb)
2831 block_stmt_iterator last_si;
2837 need_assert = false;
2838 last_si = bsi_last (bb);
2839 last = bsi_stmt (last_si);
2841 /* Look for uses of the operands in each of the sub-graphs
2842 rooted at BB. We need to check each of the outgoing edges
2843 separately, so that we know what kind of ASSERT_EXPR to
2845 FOR_EACH_EDGE (e, ei, bb->succs)
2850 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
2851 Otherwise, when we finish traversing each of the sub-graphs, we
2852 won't know whether the variables were found in the sub-graphs or
2853 if they had been found in a block upstream from BB.
2855 This is actually a bad idea is some cases, particularly jump
2856 threading. Consider a CFG like the following:
2866 Assume that one or more operands in the conditional at the
2867 end of block 0 are used in a conditional in block 2, but not
2868 anywhere in block 1. In this case we will not insert any
2869 assert statements in block 1, which may cause us to miss
2870 opportunities to optimize, particularly for jump threading. */
2871 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2872 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2874 /* Traverse the strictly dominated sub-graph rooted at E->DEST
2875 to determine if any of the operands in the conditional
2876 predicate are used. */
2878 need_assert |= find_assert_locations (e->dest);
2880 /* Register the necessary assertions for each operand in the
2881 conditional predicate. */
2882 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2883 need_assert |= register_edge_assert_for (op, e, last_si);
2886 /* Finally, indicate that we have found the operands in the
2888 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2889 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2895 /* Traverse all the statements in block BB looking for statements that
2896 may generate useful assertions for the SSA names in their operand.
2897 If a statement produces a useful assertion A for name N_i, then the
2898 list of assertions already generated for N_i is scanned to
2899 determine if A is actually needed.
2901 If N_i already had the assertion A at a location dominating the
2902 current location, then nothing needs to be done. Otherwise, the
2903 new location for A is recorded instead.
2905 1- For every statement S in BB, all the variables used by S are
2906 added to bitmap FOUND_IN_SUBGRAPH.
2908 2- If statement S uses an operand N in a way that exposes a known
2909 value range for N, then if N was not already generated by an
2910 ASSERT_EXPR, create a new assert location for N. For instance,
2911 if N is a pointer and the statement dereferences it, we can
2912 assume that N is not NULL.
2914 3- COND_EXPRs are a special case of #2. We can derive range
2915 information from the predicate but need to insert different
2916 ASSERT_EXPRs for each of the sub-graphs rooted at the
2917 conditional block. If the last statement of BB is a conditional
2918 expression of the form 'X op Y', then
2920 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
2922 b) If the conditional is the only entry point to the sub-graph
2923 corresponding to the THEN_CLAUSE, recurse into it. On
2924 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
2925 an ASSERT_EXPR is added for the corresponding variable.
2927 c) Repeat step (b) on the ELSE_CLAUSE.
2929 d) Mark X and Y in FOUND_IN_SUBGRAPH.
2938 In this case, an assertion on the THEN clause is useful to
2939 determine that 'a' is always 9 on that edge. However, an assertion
2940 on the ELSE clause would be unnecessary.
2942 4- If BB does not end in a conditional expression, then we recurse
2943 into BB's dominator children.
2945 At the end of the recursive traversal, every SSA name will have a
2946 list of locations where ASSERT_EXPRs should be added. When a new
2947 location for name N is found, it is registered by calling
2948 register_new_assert_for. That function keeps track of all the
2949 registered assertions to prevent adding unnecessary assertions.
2950 For instance, if a pointer P_4 is dereferenced more than once in a
2951 dominator tree, only the location dominating all the dereference of
2952 P_4 will receive an ASSERT_EXPR.
2954 If this function returns true, then it means that there are names
2955 for which we need to generate ASSERT_EXPRs. Those assertions are
2956 inserted by process_assert_insertions.
2958 TODO. Handle SWITCH_EXPR. */
2961 find_assert_locations (basic_block bb)
2963 block_stmt_iterator si;
2968 if (TEST_BIT (blocks_visited, bb->index))
2971 SET_BIT (blocks_visited, bb->index);
2973 need_assert = false;
2975 /* Traverse all PHI nodes in BB marking used operands. */
2976 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
2978 use_operand_p arg_p;
2981 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
2983 tree arg = USE_FROM_PTR (arg_p);
2984 if (TREE_CODE (arg) == SSA_NAME)
2986 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
2987 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
2992 /* Traverse all the statements in BB marking used names and looking
2993 for statements that may infer assertions for their used operands. */
2995 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3000 stmt = bsi_stmt (si);
3002 /* See if we can derive an assertion for any of STMT's operands. */
3003 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
3006 enum tree_code comp_code;
3008 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
3009 the sub-graph of a conditional block, when we return from
3010 this recursive walk, our parent will use the
3011 FOUND_IN_SUBGRAPH bitset to determine if one of the
3012 operands it was looking for was present in the sub-graph. */
3013 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3015 /* If OP is used only once, namely in this STMT, don't
3016 bother creating an ASSERT_EXPR for it. Such an
3017 ASSERT_EXPR would do nothing but increase compile time.
3018 Experiments show that with this simple check, we can save
3019 more than 20% of ASSERT_EXPRs. */
3020 if (has_single_use (op))
3023 /* If OP is used in such a way that we can infer a value
3024 range for it, and we don't find a previous assertion for
3025 it, create a new assertion location node for OP. */
3026 if (infer_value_range (stmt, op, &comp_code, &value))
3028 register_new_assert_for (op, comp_code, value, bb, NULL, si);
3033 /* Remember the last statement of the block. */
3037 /* If BB's last statement is a conditional expression
3038 involving integer operands, recurse into each of the sub-graphs
3039 rooted at BB to determine if we need to add ASSERT_EXPRs. */
3041 && TREE_CODE (last) == COND_EXPR
3042 && !fp_predicate (COND_EXPR_COND (last))
3043 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
3044 need_assert |= find_conditional_asserts (bb);
3046 /* Recurse into the dominator children of BB. */
3047 for (son = first_dom_son (CDI_DOMINATORS, bb);
3049 son = next_dom_son (CDI_DOMINATORS, son))
3050 need_assert |= find_assert_locations (son);
3056 /* Create an ASSERT_EXPR for NAME and insert it in the location
3057 indicated by LOC. Return true if we made any edge insertions. */
3060 process_assert_insertions_for (tree name, assert_locus_t loc)
3062 /* Build the comparison expression NAME_i COMP_CODE VAL. */
3063 tree stmt, cond, assert_expr;
3067 cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
3068 assert_expr = build_assert_expr_for (cond, name);
3072 /* We have been asked to insert the assertion on an edge. This
3073 is used only by COND_EXPR and SWITCH_EXPR assertions. */
3074 #if defined ENABLE_CHECKING
3075 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
3076 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
3079 bsi_insert_on_edge (loc->e, assert_expr);
3083 /* Otherwise, we can insert right after LOC->SI iff the
3084 statement must not be the last statement in the block. */
3085 stmt = bsi_stmt (loc->si);
3086 if (!stmt_ends_bb_p (stmt))
3088 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
3092 /* If STMT must be the last statement in BB, we can only insert new
3093 assertions on the non-abnormal edge out of BB. Note that since
3094 STMT is not control flow, there may only be one non-abnormal edge
3096 FOR_EACH_EDGE (e, ei, loc->bb->succs)
3097 if (!(e->flags & EDGE_ABNORMAL))
3099 bsi_insert_on_edge (e, assert_expr);
3107 /* Process all the insertions registered for every name N_i registered
3108 in NEED_ASSERT_FOR. The list of assertions to be inserted are
3109 found in ASSERTS_FOR[i]. */
3112 process_assert_insertions (void)
3116 bool update_edges_p = false;
3117 int num_asserts = 0;
3119 if (dump_file && (dump_flags & TDF_DETAILS))
3120 dump_all_asserts (dump_file);
3122 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3124 assert_locus_t loc = asserts_for[i];
3129 assert_locus_t next = loc->next;
3130 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
3138 bsi_commit_edge_inserts ();
3140 if (dump_file && (dump_flags & TDF_STATS))
3141 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
3146 /* Traverse the flowgraph looking for conditional jumps to insert range
3147 expressions. These range expressions are meant to provide information
3148 to optimizations that need to reason in terms of value ranges. They
3149 will not be expanded into RTL. For instance, given:
3158 this pass will transform the code into:
3164 x = ASSERT_EXPR <x, x < y>
3169 y = ASSERT_EXPR <y, x <= y>
3173 The idea is that once copy and constant propagation have run, other
3174 optimizations will be able to determine what ranges of values can 'x'
3175 take in different paths of the code, simply by checking the reaching
3176 definition of 'x'. */
3179 insert_range_assertions (void)
3185 found_in_subgraph = sbitmap_alloc (num_ssa_names);
3186 sbitmap_zero (found_in_subgraph);
3188 blocks_visited = sbitmap_alloc (last_basic_block);
3189 sbitmap_zero (blocks_visited);
3191 need_assert_for = BITMAP_ALLOC (NULL);
3192 asserts_for = XNEWVEC (assert_locus_t, num_ssa_names);
3193 memset (asserts_for, 0, num_ssa_names * sizeof (assert_locus_t));
3195 calculate_dominance_info (CDI_DOMINATORS);
3197 update_ssa_p = false;
3198 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3199 if (find_assert_locations (e->dest))
3200 update_ssa_p = true;
3204 process_assert_insertions ();
3205 update_ssa (TODO_update_ssa_no_phi);
3208 if (dump_file && (dump_flags & TDF_DETAILS))
3210 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
3211 dump_function_to_file (current_function_decl, dump_file, dump_flags);
3214 sbitmap_free (found_in_subgraph);
3216 BITMAP_FREE (need_assert_for);
3220 /* Convert range assertion expressions into the implied copies and
3221 copy propagate away the copies. Doing the trivial copy propagation
3222 here avoids the need to run the full copy propagation pass after
3225 FIXME, this will eventually lead to copy propagation removing the
3226 names that had useful range information attached to them. For
3227 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
3228 then N_i will have the range [3, +INF].
3230 However, by converting the assertion into the implied copy
3231 operation N_i = N_j, we will then copy-propagate N_j into the uses
3232 of N_i and lose the range information. We may want to hold on to
3233 ASSERT_EXPRs a little while longer as the ranges could be used in
3234 things like jump threading.
3236 The problem with keeping ASSERT_EXPRs around is that passes after
3237 VRP need to handle them appropriately.
3239 Another approach would be to make the range information a first
3240 class property of the SSA_NAME so that it can be queried from
3241 any pass. This is made somewhat more complex by the need for
3242 multiple ranges to be associated with one SSA_NAME. */
3245 remove_range_assertions (void)
3248 block_stmt_iterator si;
3250 /* Note that the BSI iterator bump happens at the bottom of the
3251 loop and no bump is necessary if we're removing the statement
3252 referenced by the current BSI. */
3254 for (si = bsi_start (bb); !bsi_end_p (si);)
3256 tree stmt = bsi_stmt (si);
3258 if (TREE_CODE (stmt) == MODIFY_EXPR
3259 && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
3261 tree rhs = TREE_OPERAND (stmt, 1);
3262 tree cond = fold (ASSERT_EXPR_COND (rhs));
3263 use_operand_p use_p;
3264 imm_use_iterator iter;
3266 gcc_assert (cond != boolean_false_node);
3267 TREE_OPERAND (stmt, 1) = ASSERT_EXPR_VAR (rhs);
3270 /* The statement is now a copy. Propagate the RHS into
3271 every use of the LHS. */
3272 FOR_EACH_IMM_USE_SAFE (use_p, iter, TREE_OPERAND (stmt, 0))
3274 SET_USE (use_p, ASSERT_EXPR_VAR (rhs));
3275 update_stmt (USE_STMT (use_p));
3278 /* And finally, remove the copy, it is not needed. */
3279 bsi_remove (&si, true);
3285 sbitmap_free (blocks_visited);
3289 /* Return true if STMT is interesting for VRP. */
3292 stmt_interesting_for_vrp (tree stmt)
3294 if (TREE_CODE (stmt) == PHI_NODE
3295 && is_gimple_reg (PHI_RESULT (stmt))
3296 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
3297 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
3299 else if (TREE_CODE (stmt) == MODIFY_EXPR)
3301 tree lhs = TREE_OPERAND (stmt, 0);
3303 if (TREE_CODE (lhs) == SSA_NAME
3304 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3305 || POINTER_TYPE_P (TREE_TYPE (lhs)))
3306 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3309 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3316 /* Initialize local data structures for VRP. */
3319 vrp_initialize (void)
3323 vr_value = XNEWVEC (value_range_t *, num_ssa_names);
3324 memset (vr_value, 0, num_ssa_names * sizeof (value_range_t *));
3328 block_stmt_iterator si;
3331 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3333 if (!stmt_interesting_for_vrp (phi))
3335 tree lhs = PHI_RESULT (phi);
3336 set_value_range_to_varying (get_value_range (lhs));
3337 DONT_SIMULATE_AGAIN (phi) = true;
3340 DONT_SIMULATE_AGAIN (phi) = false;
3343 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3345 tree stmt = bsi_stmt (si);
3347 if (!stmt_interesting_for_vrp (stmt))
3351 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
3352 set_value_range_to_varying (get_value_range (def));
3353 DONT_SIMULATE_AGAIN (stmt) = true;
3357 DONT_SIMULATE_AGAIN (stmt) = false;
3364 /* Visit assignment STMT. If it produces an interesting range, record
3365 the SSA name in *OUTPUT_P. */
3367 static enum ssa_prop_result
3368 vrp_visit_assignment (tree stmt, tree *output_p)
3373 lhs = TREE_OPERAND (stmt, 0);
3374 rhs = TREE_OPERAND (stmt, 1);
3376 /* We only keep track of ranges in integral and pointer types. */
3377 if (TREE_CODE (lhs) == SSA_NAME
3378 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3379 || POINTER_TYPE_P (TREE_TYPE (lhs))))
3382 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3384 extract_range_from_expr (&new_vr, rhs);
3386 /* If STMT is inside a loop, we may be able to know something
3387 else about the range of LHS by examining scalar evolution
3389 if (current_loops && (l = loop_containing_stmt (stmt)))
3390 adjust_range_with_scev (&new_vr, l, stmt, lhs);
3392 if (update_value_range (lhs, &new_vr))
3396 if (dump_file && (dump_flags & TDF_DETAILS))
3398 fprintf (dump_file, "Found new range for ");
3399 print_generic_expr (dump_file, lhs, 0);
3400 fprintf (dump_file, ": ");
3401 dump_value_range (dump_file, &new_vr);
3402 fprintf (dump_file, "\n\n");
3405 if (new_vr.type == VR_VARYING)
3406 return SSA_PROP_VARYING;
3408 return SSA_PROP_INTERESTING;
3411 return SSA_PROP_NOT_INTERESTING;
3414 /* Every other statement produces no useful ranges. */
3415 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3416 set_value_range_to_varying (get_value_range (def));
3418 return SSA_PROP_VARYING;
3422 /* Compare all the value ranges for names equivalent to VAR with VAL
3423 using comparison code COMP. Return the same value returned by
3424 compare_range_with_value. */
3427 compare_name_with_value (enum tree_code comp, tree var, tree val)
3434 t = retval = NULL_TREE;
3436 /* Get the set of equivalences for VAR. */
3437 e = get_value_range (var)->equiv;
3439 /* Add VAR to its own set of equivalences so that VAR's value range
3440 is processed by this loop (otherwise, we would have to replicate
3441 the body of the loop just to check VAR's value range). */
3442 bitmap_set_bit (e, SSA_NAME_VERSION (var));
3444 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
3446 value_range_t equiv_vr = *(vr_value[i]);
3448 /* If name N_i does not have a valid range, use N_i as its own
3449 range. This allows us to compare against names that may
3450 have N_i in their ranges. */
3451 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
3453 equiv_vr.type = VR_RANGE;
3454 equiv_vr.min = ssa_name (i);
3455 equiv_vr.max = ssa_name (i);
3458 t = compare_range_with_value (comp, &equiv_vr, val);
3461 /* All the ranges should compare the same against VAL. */
3462 gcc_assert (retval == NULL || t == retval);
3467 /* Remove VAR from its own equivalence set. */
3468 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
3473 /* We couldn't find a non-NULL value for the predicate. */
3478 /* Given a comparison code COMP and names N1 and N2, compare all the
3479 ranges equivalent to N1 against all the ranges equivalent to N2
3480 to determine the value of N1 COMP N2. Return the same value
3481 returned by compare_ranges. */
3484 compare_names (enum tree_code comp, tree n1, tree n2)
3488 bitmap_iterator bi1, bi2;
3491 /* Compare the ranges of every name equivalent to N1 against the
3492 ranges of every name equivalent to N2. */
3493 e1 = get_value_range (n1)->equiv;
3494 e2 = get_value_range (n2)->equiv;
3496 /* Add N1 and N2 to their own set of equivalences to avoid
3497 duplicating the body of the loop just to check N1 and N2
3499 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
3500 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
3502 /* If the equivalence sets have a common intersection, then the two
3503 names can be compared without checking their ranges. */
3504 if (bitmap_intersect_p (e1, e2))
3506 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3507 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3509 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
3511 : boolean_false_node;
3514 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3515 N2 to their own set of equivalences to avoid duplicating the body
3516 of the loop just to check N1 and N2 ranges. */
3517 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
3519 value_range_t vr1 = *(vr_value[i1]);
3521 /* If the range is VARYING or UNDEFINED, use the name itself. */
3522 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
3524 vr1.type = VR_RANGE;
3525 vr1.min = ssa_name (i1);
3526 vr1.max = ssa_name (i1);
3529 t = retval = NULL_TREE;
3530 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
3532 value_range_t vr2 = *(vr_value[i2]);
3534 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
3536 vr2.type = VR_RANGE;
3537 vr2.min = ssa_name (i2);
3538 vr2.max = ssa_name (i2);
3541 t = compare_ranges (comp, &vr1, &vr2);
3544 /* All the ranges in the equivalent sets should compare
3546 gcc_assert (retval == NULL || t == retval);
3553 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3554 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3559 /* None of the equivalent ranges are useful in computing this
3561 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3562 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3567 /* Given a conditional predicate COND, try to determine if COND yields
3568 true or false based on the value ranges of its operands. Return
3569 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3570 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3571 NULL if the conditional cannot be evaluated at compile time.
3573 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3574 the operands in COND are used when trying to compute its value.
3575 This is only used during final substitution. During propagation,
3576 we only check the range of each variable and not its equivalents. */
3579 vrp_evaluate_conditional (tree cond, bool use_equiv_p)
3581 gcc_assert (TREE_CODE (cond) == SSA_NAME
3582 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
3584 if (TREE_CODE (cond) == SSA_NAME)
3590 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node);
3593 value_range_t *vr = get_value_range (cond);
3594 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node);
3597 /* If COND has a known boolean range, return it. */
3601 /* Otherwise, if COND has a symbolic range of exactly one value,
3603 vr = get_value_range (cond);
3604 if (vr->type == VR_RANGE && vr->min == vr->max)
3609 tree op0 = TREE_OPERAND (cond, 0);
3610 tree op1 = TREE_OPERAND (cond, 1);
3612 /* We only deal with integral and pointer types. */
3613 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
3614 && !POINTER_TYPE_P (TREE_TYPE (op0)))
3619 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
3620 return compare_names (TREE_CODE (cond), op0, op1);
3621 else if (TREE_CODE (op0) == SSA_NAME)
3622 return compare_name_with_value (TREE_CODE (cond), op0, op1);
3623 else if (TREE_CODE (op1) == SSA_NAME)
3624 return compare_name_with_value (
3625 swap_tree_comparison (TREE_CODE (cond)), op1, op0);
3629 value_range_t *vr0, *vr1;
3631 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
3632 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
3635 return compare_ranges (TREE_CODE (cond), vr0, vr1);
3636 else if (vr0 && vr1 == NULL)
3637 return compare_range_with_value (TREE_CODE (cond), vr0, op1);
3638 else if (vr0 == NULL && vr1)
3639 return compare_range_with_value (
3640 swap_tree_comparison (TREE_CODE (cond)), vr1, op0);
3644 /* Anything else cannot be computed statically. */
3649 /* Visit conditional statement STMT. If we can determine which edge
3650 will be taken out of STMT's basic block, record it in
3651 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3652 SSA_PROP_VARYING. */
3654 static enum ssa_prop_result
3655 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
3659 *taken_edge_p = NULL;
3661 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3662 add ASSERT_EXPRs for them. */
3663 if (TREE_CODE (stmt) == SWITCH_EXPR)
3664 return SSA_PROP_VARYING;
3666 cond = COND_EXPR_COND (stmt);
3668 if (dump_file && (dump_flags & TDF_DETAILS))
3673 fprintf (dump_file, "\nVisiting conditional with predicate: ");
3674 print_generic_expr (dump_file, cond, 0);
3675 fprintf (dump_file, "\nWith known ranges\n");
3677 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
3679 fprintf (dump_file, "\t");
3680 print_generic_expr (dump_file, use, 0);
3681 fprintf (dump_file, ": ");
3682 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
3685 fprintf (dump_file, "\n");
3688 /* Compute the value of the predicate COND by checking the known
3689 ranges of each of its operands.
3691 Note that we cannot evaluate all the equivalent ranges here
3692 because those ranges may not yet be final and with the current
3693 propagation strategy, we cannot determine when the value ranges
3694 of the names in the equivalence set have changed.
3696 For instance, given the following code fragment
3700 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3704 Assume that on the first visit to i_14, i_5 has the temporary
3705 range [8, 8] because the second argument to the PHI function is
3706 not yet executable. We derive the range ~[0, 0] for i_14 and the
3707 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3708 the first time, since i_14 is equivalent to the range [8, 8], we
3709 determine that the predicate is always false.
3711 On the next round of propagation, i_13 is determined to be
3712 VARYING, which causes i_5 to drop down to VARYING. So, another
3713 visit to i_14 is scheduled. In this second visit, we compute the
3714 exact same range and equivalence set for i_14, namely ~[0, 0] and
3715 { i_5 }. But we did not have the previous range for i_5
3716 registered, so vrp_visit_assignment thinks that the range for
3717 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3718 is not visited again, which stops propagation from visiting
3719 statements in the THEN clause of that if().
3721 To properly fix this we would need to keep the previous range
3722 value for the names in the equivalence set. This way we would've
3723 discovered that from one visit to the other i_5 changed from
3724 range [8, 8] to VR_VARYING.
3726 However, fixing this apparent limitation may not be worth the
3727 additional checking. Testing on several code bases (GCC, DLV,
3728 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3729 4 more predicates folded in SPEC. */
3730 val = vrp_evaluate_conditional (cond, false);
3732 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
3734 if (dump_file && (dump_flags & TDF_DETAILS))
3736 fprintf (dump_file, "\nPredicate evaluates to: ");
3737 if (val == NULL_TREE)
3738 fprintf (dump_file, "DON'T KNOW\n");
3740 print_generic_stmt (dump_file, val, 0);
3743 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
3747 /* Evaluate statement STMT. If the statement produces a useful range,
3748 return SSA_PROP_INTERESTING and record the SSA name with the
3749 interesting range into *OUTPUT_P.
3751 If STMT is a conditional branch and we can determine its truth
3752 value, the taken edge is recorded in *TAKEN_EDGE_P.
3754 If STMT produces a varying value, return SSA_PROP_VARYING. */
3756 static enum ssa_prop_result
3757 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
3763 if (dump_file && (dump_flags & TDF_DETAILS))
3765 fprintf (dump_file, "\nVisiting statement:\n");
3766 print_generic_stmt (dump_file, stmt, dump_flags);
3767 fprintf (dump_file, "\n");
3770 ann = stmt_ann (stmt);
3771 if (TREE_CODE (stmt) == MODIFY_EXPR
3772 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3773 return vrp_visit_assignment (stmt, output_p);
3774 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3775 return vrp_visit_cond_stmt (stmt, taken_edge_p);
3777 /* All other statements produce nothing of interest for VRP, so mark
3778 their outputs varying and prevent further simulation. */
3779 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3780 set_value_range_to_varying (get_value_range (def));
3782 return SSA_PROP_VARYING;
3786 /* Meet operation for value ranges. Given two value ranges VR0 and
3787 VR1, store in VR0 the result of meeting VR0 and VR1.
3789 The meeting rules are as follows:
3791 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
3793 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
3794 union of VR0 and VR1. */
3797 vrp_meet (value_range_t *vr0, value_range_t *vr1)
3799 if (vr0->type == VR_UNDEFINED)
3801 copy_value_range (vr0, vr1);
3805 if (vr1->type == VR_UNDEFINED)
3807 /* Nothing to do. VR0 already has the resulting range. */
3811 if (vr0->type == VR_VARYING)
3813 /* Nothing to do. VR0 already has the resulting range. */
3817 if (vr1->type == VR_VARYING)
3819 set_value_range_to_varying (vr0);
3823 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
3825 /* If VR0 and VR1 have a non-empty intersection, compute the
3826 union of both ranges. */
3827 if (value_ranges_intersect_p (vr0, vr1))
3832 /* The lower limit of the new range is the minimum of the
3833 two ranges. If they cannot be compared, the result is
3835 cmp = compare_values (vr0->min, vr1->min);
3836 if (cmp == 0 || cmp == 1)
3842 set_value_range_to_varying (vr0);
3846 /* Similarly, the upper limit of the new range is the
3847 maximum of the two ranges. If they cannot be compared,
3848 the result is VARYING. */
3849 cmp = compare_values (vr0->max, vr1->max);
3850 if (cmp == 0 || cmp == -1)
3856 set_value_range_to_varying (vr0);
3860 /* The resulting set of equivalences is the intersection of
3862 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3863 bitmap_and_into (vr0->equiv, vr1->equiv);
3864 else if (vr0->equiv && !vr1->equiv)
3865 bitmap_clear (vr0->equiv);
3867 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
3872 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
3874 /* Two anti-ranges meet only if they are both identical. */
3875 if (compare_values (vr0->min, vr1->min) == 0
3876 && compare_values (vr0->max, vr1->max) == 0
3877 && compare_values (vr0->min, vr0->max) == 0)
3879 /* The resulting set of equivalences is the intersection of
3881 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3882 bitmap_and_into (vr0->equiv, vr1->equiv);
3883 else if (vr0->equiv && !vr1->equiv)
3884 bitmap_clear (vr0->equiv);
3889 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
3891 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
3892 meet only if the ranges have an empty intersection. The
3893 result of the meet operation is the anti-range. */
3894 if (!symbolic_range_p (vr0)
3895 && !symbolic_range_p (vr1)
3896 && !value_ranges_intersect_p (vr0, vr1))
3898 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
3899 set. We need to compute the intersection of the two
3900 equivalence sets. */
3901 if (vr1->type == VR_ANTI_RANGE)
3902 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
3904 /* The resulting set of equivalences is the intersection of
3906 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3907 bitmap_and_into (vr0->equiv, vr1->equiv);
3908 else if (vr0->equiv && !vr1->equiv)
3909 bitmap_clear (vr0->equiv);
3920 /* The two range VR0 and VR1 do not meet. Before giving up and
3921 setting the result to VARYING, see if we can at least derive a
3922 useful anti-range. FIXME, all this nonsense about distinguishing
3923 anti-ranges from ranges is necessary because of the odd
3924 semantics of range_includes_zero_p and friends. */
3925 if (!symbolic_range_p (vr0)
3926 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
3927 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
3928 && !symbolic_range_p (vr1)
3929 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
3930 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
3932 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
3934 /* Since this meet operation did not result from the meeting of
3935 two equivalent names, VR0 cannot have any equivalences. */
3937 bitmap_clear (vr0->equiv);
3940 set_value_range_to_varying (vr0);
3944 /* Visit all arguments for PHI node PHI that flow through executable
3945 edges. If a valid value range can be derived from all the incoming
3946 value ranges, set a new range for the LHS of PHI. */
3948 static enum ssa_prop_result
3949 vrp_visit_phi_node (tree phi)
3952 tree lhs = PHI_RESULT (phi);
3953 value_range_t *lhs_vr = get_value_range (lhs);
3954 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3956 copy_value_range (&vr_result, lhs_vr);
3958 if (dump_file && (dump_flags & TDF_DETAILS))
3960 fprintf (dump_file, "\nVisiting PHI node: ");
3961 print_generic_expr (dump_file, phi, dump_flags);
3964 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
3966 edge e = PHI_ARG_EDGE (phi, i);
3968 if (dump_file && (dump_flags & TDF_DETAILS))
3971 "\n Argument #%d (%d -> %d %sexecutable)\n",
3972 i, e->src->index, e->dest->index,
3973 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
3976 if (e->flags & EDGE_EXECUTABLE)
3978 tree arg = PHI_ARG_DEF (phi, i);
3979 value_range_t vr_arg;
3981 if (TREE_CODE (arg) == SSA_NAME)
3982 vr_arg = *(get_value_range (arg));
3985 vr_arg.type = VR_RANGE;
3988 vr_arg.equiv = NULL;
3991 if (dump_file && (dump_flags & TDF_DETAILS))
3993 fprintf (dump_file, "\t");
3994 print_generic_expr (dump_file, arg, dump_flags);
3995 fprintf (dump_file, "\n\tValue: ");
3996 dump_value_range (dump_file, &vr_arg);
3997 fprintf (dump_file, "\n");
4000 vrp_meet (&vr_result, &vr_arg);
4002 if (vr_result.type == VR_VARYING)
4007 if (vr_result.type == VR_VARYING)
4010 /* To prevent infinite iterations in the algorithm, derive ranges
4011 when the new value is slightly bigger or smaller than the
4013 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE)
4015 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
4017 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
4018 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
4020 /* If the new minimum is smaller or larger than the previous
4021 one, go all the way to -INF. In the first case, to avoid
4022 iterating millions of times to reach -INF, and in the
4023 other case to avoid infinite bouncing between different
4025 if (cmp_min > 0 || cmp_min < 0)
4026 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
4028 /* Similarly, if the new maximum is smaller or larger than
4029 the previous one, go all the way to +INF. */
4030 if (cmp_max < 0 || cmp_max > 0)
4031 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
4033 /* If we ended up with a (-INF, +INF) range, set it to
4035 if (vr_result.min == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))
4036 && vr_result.max == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)))
4041 /* If the new range is different than the previous value, keep
4043 if (update_value_range (lhs, &vr_result))
4044 return SSA_PROP_INTERESTING;
4046 /* Nothing changed, don't add outgoing edges. */
4047 return SSA_PROP_NOT_INTERESTING;
4049 /* No match found. Set the LHS to VARYING. */
4051 set_value_range_to_varying (lhs_vr);
4052 return SSA_PROP_VARYING;
4055 /* Simplify a division or modulo operator to a right shift or
4056 bitwise and if the first operand is unsigned or is greater
4057 than zero and the second operand is an exact power of two. */
4060 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
4063 tree op = TREE_OPERAND (rhs, 0);
4064 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
4066 if (TYPE_UNSIGNED (TREE_TYPE (op)))
4068 val = integer_one_node;
4072 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node);
4075 if (val && integer_onep (val))
4078 tree op0 = TREE_OPERAND (rhs, 0);
4079 tree op1 = TREE_OPERAND (rhs, 1);
4081 if (rhs_code == TRUNC_DIV_EXPR)
4083 t = build_int_cst (NULL_TREE, tree_log2 (op1));
4084 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
4088 t = build_int_cst (TREE_TYPE (op1), 1);
4089 t = int_const_binop (MINUS_EXPR, op1, t, 0);
4090 t = fold_convert (TREE_TYPE (op0), t);
4091 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
4094 TREE_OPERAND (stmt, 1) = t;
4099 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
4100 ABS_EXPR. If the operand is <= 0, then simplify the
4101 ABS_EXPR into a NEGATE_EXPR. */
4104 simplify_abs_using_ranges (tree stmt, tree rhs)
4107 tree op = TREE_OPERAND (rhs, 0);
4108 tree type = TREE_TYPE (op);
4109 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
4111 if (TYPE_UNSIGNED (type))
4113 val = integer_zero_node;
4117 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node);
4120 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node);
4124 if (integer_zerop (val))
4125 val = integer_one_node;
4126 else if (integer_onep (val))
4127 val = integer_zero_node;
4132 && (integer_onep (val) || integer_zerop (val)))
4136 if (integer_onep (val))
4137 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
4141 TREE_OPERAND (stmt, 1) = t;
4147 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
4148 a known value range VR.
4150 If there is one and only one value which will satisfy the
4151 conditional, then return that value. Else return NULL. */
4154 test_for_singularity (enum tree_code cond_code, tree op0,
4155 tree op1, value_range_t *vr)
4160 /* Extract minimum/maximum values which satisfy the
4161 the conditional as it was written. */
4162 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
4164 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
4167 if (cond_code == LT_EXPR)
4169 tree one = build_int_cst (TREE_TYPE (op0), 1);
4170 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
4173 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
4175 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
4178 if (cond_code == GT_EXPR)
4180 tree one = build_int_cst (TREE_TYPE (op0), 1);
4181 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
4185 /* Now refine the minimum and maximum values using any
4186 value range information we have for op0. */
4189 if (compare_values (vr->min, min) == -1)
4193 if (compare_values (vr->max, max) == 1)
4198 /* If the new min/max values have converged to a single value,
4199 then there is only one value which can satisfy the condition,
4200 return that value. */
4201 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
4207 /* Simplify a conditional using a relational operator to an equality
4208 test if the range information indicates only one value can satisfy
4209 the original conditional. */
4212 simplify_cond_using_ranges (tree stmt)
4214 tree cond = COND_EXPR_COND (stmt);
4215 tree op0 = TREE_OPERAND (cond, 0);
4216 tree op1 = TREE_OPERAND (cond, 1);
4217 enum tree_code cond_code = TREE_CODE (cond);
4219 if (cond_code != NE_EXPR
4220 && cond_code != EQ_EXPR
4221 && TREE_CODE (op0) == SSA_NAME
4222 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
4223 && is_gimple_min_invariant (op1))
4225 value_range_t *vr = get_value_range (op0);
4227 /* If we have range information for OP0, then we might be
4228 able to simplify this conditional. */
4229 if (vr->type == VR_RANGE)
4231 tree new = test_for_singularity (cond_code, op0, op1, vr);
4237 fprintf (dump_file, "Simplified relational ");
4238 print_generic_expr (dump_file, cond, 0);
4239 fprintf (dump_file, " into ");
4242 COND_EXPR_COND (stmt)
4243 = build2 (EQ_EXPR, boolean_type_node, op0, new);
4248 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4249 fprintf (dump_file, "\n");
4255 /* Try again after inverting the condition. We only deal
4256 with integral types here, so no need to worry about
4257 issues with inverting FP comparisons. */
4258 cond_code = invert_tree_comparison (cond_code, false);
4259 new = test_for_singularity (cond_code, op0, op1, vr);
4265 fprintf (dump_file, "Simplified relational ");
4266 print_generic_expr (dump_file, cond, 0);
4267 fprintf (dump_file, " into ");
4270 COND_EXPR_COND (stmt)
4271 = build2 (NE_EXPR, boolean_type_node, op0, new);
4276 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4277 fprintf (dump_file, "\n");
4286 /* Simplify STMT using ranges if possible. */
4289 simplify_stmt_using_ranges (tree stmt)
4291 if (TREE_CODE (stmt) == MODIFY_EXPR)
4293 tree rhs = TREE_OPERAND (stmt, 1);
4294 enum tree_code rhs_code = TREE_CODE (rhs);
4296 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
4297 and BIT_AND_EXPR respectively if the first operand is greater
4298 than zero and the second operand is an exact power of two. */
4299 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
4300 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
4301 && integer_pow2p (TREE_OPERAND (rhs, 1)))
4302 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
4304 /* Transform ABS (X) into X or -X as appropriate. */
4305 if (rhs_code == ABS_EXPR
4306 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
4307 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
4308 simplify_abs_using_ranges (stmt, rhs);
4310 else if (TREE_CODE (stmt) == COND_EXPR
4311 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
4313 simplify_cond_using_ranges (stmt);
4317 /* Stack of dest,src equivalency pairs that need to be restored after
4318 each attempt to thread a block's incoming edge to an outgoing edge.
4320 A NULL entry is used to mark the end of pairs which need to be
4322 static VEC(tree,heap) *stack;
4324 /* A trivial wrapper so that we can present the generic jump
4325 threading code with a simple API for simplifying statements. */
4327 simplify_stmt_for_jump_threading (tree stmt)
4329 /* We only use VRP information to simplify conditionals. This is
4330 overly conservative, but it's unclear if doing more would be
4331 worth the compile time cost. */
4332 if (TREE_CODE (stmt) != COND_EXPR)
4335 return vrp_evaluate_conditional (COND_EXPR_COND (stmt), true);
4338 /* Blocks which have more than one predecessor and more than
4339 one successor present jump threading opportunities. ie,
4340 when the block is reached from a specific predecessor, we
4341 may be able to determine which of the outgoing edges will
4342 be traversed. When this optimization applies, we are able
4343 to avoid conditionals at runtime and we may expose secondary
4344 optimization opportunities.
4346 This routine is effectively a driver for the generic jump
4347 threading code. It basically just presents the generic code
4348 with edges that may be suitable for jump threading.
4350 Unlike DOM, we do not iterate VRP if jump threading was successful.
4351 While iterating may expose new opportunities for VRP, it is expected
4352 those opportunities would be very limited and the compile time cost
4353 to expose those opportunities would be significant.
4355 As jump threading opportunities are discovered, they are registered
4356 for later realization. */
4359 identify_jump_threads (void)
4364 /* Ugh. When substituting values earlier in this pass we can
4365 wipe the dominance information. So rebuild the dominator
4366 information as we need it within the jump threading code. */
4367 calculate_dominance_info (CDI_DOMINATORS);
4369 /* We do not allow VRP information to be used for jump threading
4370 across a back edge in the CFG. Otherwise it becomes too
4371 difficult to avoid eliminating loop exit tests. Of course
4372 EDGE_DFS_BACK is not accurate at this time so we have to
4374 mark_dfs_back_edges ();
4376 /* Allocate our unwinder stack to unwind any temporary equivalences
4377 that might be recorded. */
4378 stack = VEC_alloc (tree, heap, 20);
4380 /* To avoid lots of silly node creation, we create a single
4381 conditional and just modify it in-place when attempting to
4383 dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL);
4384 dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL);
4386 /* Walk through all the blocks finding those which present a
4387 potential jump threading opportunity. We could set this up
4388 as a dominator walker and record data during the walk, but
4389 I doubt it's worth the effort for the classes of jump
4390 threading opportunities we are trying to identify at this
4391 point in compilation. */
4396 /* If the generic jump threading code does not find this block
4397 interesting, then there is nothing to do. */
4398 if (! potentially_threadable_block (bb))
4401 /* We only care about blocks ending in a COND_EXPR. While there
4402 may be some value in handling SWITCH_EXPR here, I doubt it's
4403 terribly important. */
4404 last = bsi_stmt (bsi_last (bb));
4405 if (TREE_CODE (last) != COND_EXPR)
4408 /* We're basically looking for any kind of conditional with
4409 integral type arguments. */
4410 cond = COND_EXPR_COND (last);
4411 if ((TREE_CODE (cond) == SSA_NAME
4412 && INTEGRAL_TYPE_P (TREE_TYPE (cond)))
4413 || (COMPARISON_CLASS_P (cond)
4414 && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
4415 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0)))
4416 && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME
4417 || is_gimple_min_invariant (TREE_OPERAND (cond, 1)))
4418 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
4423 /* We've got a block with multiple predecessors and multiple
4424 successors which also ends in a suitable conditional. For
4425 each predecessor, see if we can thread it to a specific
4427 FOR_EACH_EDGE (e, ei, bb->preds)
4429 /* Do not thread across back edges or abnormal edges
4431 if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
4434 thread_across_edge (dummy, e, true,
4436 simplify_stmt_for_jump_threading);
4441 /* We do not actually update the CFG or SSA graphs at this point as
4442 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
4443 handle ASSERT_EXPRs gracefully. */
4446 /* We identified all the jump threading opportunities earlier, but could
4447 not transform the CFG at that time. This routine transforms the
4448 CFG and arranges for the dominator tree to be rebuilt if necessary.
4450 Note the SSA graph update will occur during the normal TODO
4451 processing by the pass manager. */
4453 finalize_jump_threads (void)
4455 bool cfg_altered = false;
4456 cfg_altered = thread_through_all_blocks ();
4458 /* If we threaded jumps, then we need to recompute the dominance
4459 information, to safely do that we must clean up the CFG first. */
4462 free_dominance_info (CDI_DOMINATORS);
4463 cleanup_tree_cfg ();
4464 calculate_dominance_info (CDI_DOMINATORS);
4466 VEC_free (tree, heap, stack);
4470 /* Traverse all the blocks folding conditionals with known ranges. */
4476 prop_value_t *single_val_range;
4477 bool do_value_subst_p;
4481 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
4482 dump_all_value_ranges (dump_file);
4483 fprintf (dump_file, "\n");
4486 /* We may have ended with ranges that have exactly one value. Those
4487 values can be substituted as any other copy/const propagated
4488 value using substitute_and_fold. */
4489 single_val_range = XNEWVEC (prop_value_t, num_ssa_names);
4490 memset (single_val_range, 0, num_ssa_names * sizeof (*single_val_range));
4492 do_value_subst_p = false;
4493 for (i = 0; i < num_ssa_names; i++)
4495 && vr_value[i]->type == VR_RANGE
4496 && vr_value[i]->min == vr_value[i]->max)
4498 single_val_range[i].value = vr_value[i]->min;
4499 do_value_subst_p = true;
4502 if (!do_value_subst_p)
4504 /* We found no single-valued ranges, don't waste time trying to
4505 do single value substitution in substitute_and_fold. */
4506 free (single_val_range);
4507 single_val_range = NULL;
4510 substitute_and_fold (single_val_range, true);
4512 /* We must identify jump threading opportunities before we release
4513 the datastructures built by VRP. */
4514 identify_jump_threads ();
4516 /* Free allocated memory. */
4517 for (i = 0; i < num_ssa_names; i++)
4520 BITMAP_FREE (vr_value[i]->equiv);
4524 free (single_val_range);
4527 /* So that we can distinguish between VRP data being available
4528 and not available. */
4533 /* Main entry point to VRP (Value Range Propagation). This pass is
4534 loosely based on J. R. C. Patterson, ``Accurate Static Branch
4535 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
4536 Programming Language Design and Implementation, pp. 67-78, 1995.
4537 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
4539 This is essentially an SSA-CCP pass modified to deal with ranges
4540 instead of constants.
4542 While propagating ranges, we may find that two or more SSA name
4543 have equivalent, though distinct ranges. For instance,
4546 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
4548 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
4552 In the code above, pointer p_5 has range [q_2, q_2], but from the
4553 code we can also determine that p_5 cannot be NULL and, if q_2 had
4554 a non-varying range, p_5's range should also be compatible with it.
4556 These equivalences are created by two expressions: ASSERT_EXPR and
4557 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
4558 result of another assertion, then we can use the fact that p_5 and
4559 p_4 are equivalent when evaluating p_5's range.
4561 Together with value ranges, we also propagate these equivalences
4562 between names so that we can take advantage of information from
4563 multiple ranges when doing final replacement. Note that this
4564 equivalency relation is transitive but not symmetric.
4566 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
4567 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
4568 in contexts where that assertion does not hold (e.g., in line 6).
4570 TODO, the main difference between this pass and Patterson's is that
4571 we do not propagate edge probabilities. We only compute whether
4572 edges can be taken or not. That is, instead of having a spectrum
4573 of jump probabilities between 0 and 1, we only deal with 0, 1 and
4574 DON'T KNOW. In the future, it may be worthwhile to propagate
4575 probabilities to aid branch prediction. */
4580 insert_range_assertions ();
4582 current_loops = loop_optimizer_init (LOOPS_NORMAL);
4584 scev_initialize (current_loops);
4587 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
4593 loop_optimizer_finalize (current_loops);
4594 current_loops = NULL;
4597 /* ASSERT_EXPRs must be removed before finalizing jump threads
4598 as finalizing jump threads calls the CFG cleanup code which
4599 does not properly handle ASSERT_EXPRs. */
4600 remove_range_assertions ();
4602 /* If we exposed any new variables, go ahead and put them into
4603 SSA form now, before we handle jump threading. This simplifies
4604 interactions between rewriting of _DECL nodes into SSA form
4605 and rewriting SSA_NAME nodes into SSA form after block
4606 duplication and CFG manipulation. */
4607 update_ssa (TODO_update_ssa);
4609 finalize_jump_threads ();
4616 return flag_tree_vrp != 0;
4619 struct tree_opt_pass pass_vrp =
4622 gate_vrp, /* gate */
4623 execute_vrp, /* execute */
4626 0, /* static_pass_number */
4627 TV_TREE_VRP, /* tv_id */
4628 PROP_ssa | PROP_alias, /* properties_required */
4629 0, /* properties_provided */
4630 0, /* properties_destroyed */
4631 0, /* todo_flags_start */
4636 | TODO_update_ssa, /* todo_flags_finish */