1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
24 #include "coretypes.h"
29 #include "basic-block.h"
30 #include "tree-flow.h"
31 #include "tree-pass.h"
32 #include "tree-dump.h"
34 #include "diagnostic.h"
36 #include "tree-scalar-evolution.h"
37 #include "tree-ssa-propagate.h"
38 #include "tree-chrec.h"
40 /* Set of SSA names found during the dominator traversal of a
41 sub-graph in find_assert_locations. */
42 static sbitmap found_in_subgraph;
44 /* Loop structure of the program. Used to analyze scalar evolutions
45 inside adjust_range_with_scev. */
46 static struct loops *cfg_loops;
48 /* Local functions. */
49 static int compare_values (tree val1, tree val2);
51 /* Location information for ASSERT_EXPRs. Each instance of this
52 structure describes an ASSERT_EXPR for an SSA name. Since a single
53 SSA name may have more than one assertion associated with it, these
54 locations are kept in a linked list attached to the corresponding
58 /* Basic block where the assertion would be inserted. */
61 /* Some assertions need to be inserted on an edge (e.g., assertions
62 generated by COND_EXPRs). In those cases, BB will be NULL. */
65 /* Pointer to the statement that generated this assertion. */
66 block_stmt_iterator si;
68 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
69 enum tree_code comp_code;
71 /* Value being compared against. */
74 /* Next node in the linked list. */
75 struct assert_locus_d *next;
78 typedef struct assert_locus_d *assert_locus_t;
80 /* If bit I is present, it means that SSA name N_i has a list of
81 assertions that should be inserted in the IL. */
82 static bitmap need_assert_for;
84 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
85 holds a list of ASSERT_LOCUS_T nodes that describe where
86 ASSERT_EXPRs for SSA name N_I should be inserted. */
87 static assert_locus_t *asserts_for;
89 /* Set of blocks visited in find_assert_locations. Used to avoid
90 visiting the same block more than once. */
91 static sbitmap blocks_visited;
93 /* Value range array. After propagation, VR_VALUE[I] holds the range
94 of values that SSA name N_I may take. */
95 static value_range_t **vr_value;
98 /* Return true if ARG is marked with the nonnull attribute in the
99 current function signature. */
102 nonnull_arg_p (tree arg)
104 tree t, attrs, fntype;
105 unsigned HOST_WIDE_INT arg_num;
107 gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
109 fntype = TREE_TYPE (current_function_decl);
110 attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype));
112 /* If "nonnull" wasn't specified, we know nothing about the argument. */
113 if (attrs == NULL_TREE)
116 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
117 if (TREE_VALUE (attrs) == NULL_TREE)
120 /* Get the position number for ARG in the function signature. */
121 for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl);
123 t = TREE_CHAIN (t), arg_num++)
129 gcc_assert (t == arg);
131 /* Now see if ARG_NUM is mentioned in the nonnull list. */
132 for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
134 if (compare_tree_int (TREE_VALUE (t), arg_num) == 0)
142 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
145 set_value_range (value_range_t *vr, enum value_range_type t, tree min,
146 tree max, bitmap equiv)
148 #if defined ENABLE_CHECKING
149 /* Check the validity of the range. */
150 if (t == VR_RANGE || t == VR_ANTI_RANGE)
154 gcc_assert (min && max);
156 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
157 gcc_assert (min != TYPE_MIN_VALUE (TREE_TYPE (min))
158 || max != TYPE_MAX_VALUE (TREE_TYPE (max)));
160 cmp = compare_values (min, max);
161 gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
164 if (t == VR_UNDEFINED || t == VR_VARYING)
165 gcc_assert (min == NULL_TREE && max == NULL_TREE);
167 if (t == VR_UNDEFINED || t == VR_VARYING)
168 gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
175 /* Since updating the equivalence set involves deep copying the
176 bitmaps, only do it if absolutely necessary. */
177 if (vr->equiv == NULL)
178 vr->equiv = BITMAP_ALLOC (NULL);
180 if (equiv != vr->equiv)
182 if (equiv && !bitmap_empty_p (equiv))
183 bitmap_copy (vr->equiv, equiv);
185 bitmap_clear (vr->equiv);
190 /* Copy value range FROM into value range TO. */
193 copy_value_range (value_range_t *to, value_range_t *from)
195 set_value_range (to, from->type, from->min, from->max, from->equiv);
199 /* Set value range VR to a non-NULL range of type TYPE. */
202 set_value_range_to_nonnull (value_range_t *vr, tree type)
204 tree zero = build_int_cst (type, 0);
205 set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
209 /* Set value range VR to a NULL range of type TYPE. */
212 set_value_range_to_null (value_range_t *vr, tree type)
214 tree zero = build_int_cst (type, 0);
215 set_value_range (vr, VR_RANGE, zero, zero, vr->equiv);
219 /* Set value range VR to VR_VARYING. */
222 set_value_range_to_varying (value_range_t *vr)
224 vr->type = VR_VARYING;
225 vr->min = vr->max = NULL_TREE;
227 bitmap_clear (vr->equiv);
231 /* Set value range VR to VR_UNDEFINED. */
234 set_value_range_to_undefined (value_range_t *vr)
236 vr->type = VR_UNDEFINED;
237 vr->min = vr->max = NULL_TREE;
239 bitmap_clear (vr->equiv);
243 /* Return value range information for VAR. Create an empty range
246 static value_range_t *
247 get_value_range (tree var)
251 unsigned ver = SSA_NAME_VERSION (var);
257 /* Create a default value range. */
258 vr_value[ver] = vr = xmalloc (sizeof (*vr));
259 memset (vr, 0, sizeof (*vr));
261 /* Allocate an equivalence set. */
262 vr->equiv = BITMAP_ALLOC (NULL);
264 /* If VAR is a default definition, the variable can take any value
266 sym = SSA_NAME_VAR (var);
267 if (var == default_def (sym))
269 /* Try to use the "nonnull" attribute to create ~[0, 0]
270 anti-ranges for pointers. Note that this is only valid with
271 default definitions of PARM_DECLs. */
272 if (TREE_CODE (sym) == PARM_DECL
273 && POINTER_TYPE_P (TREE_TYPE (sym))
274 && nonnull_arg_p (sym))
275 set_value_range_to_nonnull (vr, TREE_TYPE (sym));
277 set_value_range_to_varying (vr);
284 /* Update the value range and equivalence set for variable VAR to
285 NEW_VR. Return true if NEW_VR is different from VAR's previous
288 NOTE: This function assumes that NEW_VR is a temporary value range
289 object created for the sole purpose of updating VAR's range. The
290 storage used by the equivalence set from NEW_VR will be freed by
291 this function. Do not call update_value_range when NEW_VR
292 is the range object associated with another SSA name. */
295 update_value_range (tree var, value_range_t *new_vr)
297 value_range_t *old_vr;
300 /* Update the value range, if necessary. */
301 old_vr = get_value_range (var);
302 is_new = old_vr->type != new_vr->type
303 || old_vr->min != new_vr->min
304 || old_vr->max != new_vr->max
305 || (old_vr->equiv == NULL && new_vr->equiv)
306 || (old_vr->equiv && new_vr->equiv == NULL)
307 || (!bitmap_equal_p (old_vr->equiv, new_vr->equiv));
310 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
313 BITMAP_FREE (new_vr->equiv);
314 new_vr->equiv = NULL;
320 /* Add VAR and VAR's equivalence set to EQUIV. */
323 add_equivalence (bitmap equiv, tree var)
325 unsigned ver = SSA_NAME_VERSION (var);
326 value_range_t *vr = vr_value[ver];
328 bitmap_set_bit (equiv, ver);
330 bitmap_ior_into (equiv, vr->equiv);
334 /* Return true if VR is ~[0, 0]. */
337 range_is_nonnull (value_range_t *vr)
339 return vr->type == VR_ANTI_RANGE
340 && integer_zerop (vr->min)
341 && integer_zerop (vr->max);
345 /* Return true if VR is [0, 0]. */
348 range_is_null (value_range_t *vr)
350 return vr->type == VR_RANGE
351 && integer_zerop (vr->min)
352 && integer_zerop (vr->max);
356 /* Return true if value range VR involves at least one symbol. */
359 symbolic_range_p (value_range_t *vr)
361 return (!is_gimple_min_invariant (vr->min)
362 || !is_gimple_min_invariant (vr->max));
366 /* Like tree_expr_nonzero_p, but this function uses value ranges
370 vrp_expr_computes_nonzero (tree expr)
372 if (tree_expr_nonzero_p (expr))
375 /* If we have an expression of the form &X->a, then the expression
376 is nonnull if X is nonnull. */
377 if (TREE_CODE (expr) == ADDR_EXPR)
379 tree base = get_base_address (TREE_OPERAND (expr, 0));
381 if (base != NULL_TREE
382 && TREE_CODE (base) == INDIRECT_REF
383 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
385 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
386 if (range_is_nonnull (vr))
395 /* Compare two values VAL1 and VAL2. Return
397 -2 if VAL1 and VAL2 cannot be compared at compile-time,
400 +1 if VAL1 > VAL2, and
403 This is similar to tree_int_cst_compare but supports pointer values
404 and values that cannot be compared at compile time. */
407 compare_values (tree val1, tree val2)
412 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
414 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
415 == POINTER_TYPE_P (TREE_TYPE (val2)));
417 /* Do some limited symbolic comparisons. */
418 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
420 /* We can determine some comparisons against +INF and -INF even
421 if the other value is an expression. */
422 if (val1 == TYPE_MAX_VALUE (TREE_TYPE (val1))
423 && TREE_CODE (val2) == MINUS_EXPR)
425 /* +INF > NAME - CST. */
428 else if (val1 == TYPE_MIN_VALUE (TREE_TYPE (val1))
429 && TREE_CODE (val2) == PLUS_EXPR)
431 /* -INF < NAME + CST. */
434 else if (TREE_CODE (val1) == MINUS_EXPR
435 && val2 == TYPE_MAX_VALUE (TREE_TYPE (val2)))
437 /* NAME - CST < +INF. */
440 else if (TREE_CODE (val1) == PLUS_EXPR
441 && val2 == TYPE_MIN_VALUE (TREE_TYPE (val2)))
443 /* NAME + CST > -INF. */
448 if ((TREE_CODE (val1) == SSA_NAME
449 || TREE_CODE (val1) == PLUS_EXPR
450 || TREE_CODE (val1) == MINUS_EXPR)
451 && (TREE_CODE (val2) == SSA_NAME
452 || TREE_CODE (val2) == PLUS_EXPR
453 || TREE_CODE (val2) == MINUS_EXPR))
457 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
458 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
459 same name, return -2. */
460 if (TREE_CODE (val1) == SSA_NAME)
467 n1 = TREE_OPERAND (val1, 0);
468 c1 = TREE_OPERAND (val1, 1);
471 if (TREE_CODE (val2) == SSA_NAME)
478 n2 = TREE_OPERAND (val2, 0);
479 c2 = TREE_OPERAND (val2, 1);
482 /* Both values must use the same name. */
486 if (TREE_CODE (val1) == SSA_NAME)
488 if (TREE_CODE (val2) == SSA_NAME)
491 else if (TREE_CODE (val2) == PLUS_EXPR)
492 /* NAME < NAME + CST */
494 else if (TREE_CODE (val2) == MINUS_EXPR)
495 /* NAME > NAME - CST */
498 else if (TREE_CODE (val1) == PLUS_EXPR)
500 if (TREE_CODE (val2) == SSA_NAME)
501 /* NAME + CST > NAME */
503 else if (TREE_CODE (val2) == PLUS_EXPR)
504 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
505 return compare_values (c1, c2);
506 else if (TREE_CODE (val2) == MINUS_EXPR)
507 /* NAME + CST1 > NAME - CST2 */
510 else if (TREE_CODE (val1) == MINUS_EXPR)
512 if (TREE_CODE (val2) == SSA_NAME)
513 /* NAME - CST < NAME */
515 else if (TREE_CODE (val2) == PLUS_EXPR)
516 /* NAME - CST1 < NAME + CST2 */
518 else if (TREE_CODE (val2) == MINUS_EXPR)
519 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
520 C1 and C2 are swapped in the call to compare_values. */
521 return compare_values (c2, c1);
527 /* We cannot compare non-constants. */
528 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
531 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
533 /* We cannot compare overflowed values. */
534 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
537 return tree_int_cst_compare (val1, val2);
543 /* First see if VAL1 and VAL2 are not the same. */
544 if (val1 == val2 || operand_equal_p (val1, val2, 0))
547 /* If VAL1 is a lower address than VAL2, return -1. */
548 t = fold_binary (LT_EXPR, boolean_type_node, val1, val2);
549 if (t == boolean_true_node)
552 /* If VAL1 is a higher address than VAL2, return +1. */
553 t = fold_binary (GT_EXPR, boolean_type_node, val1, val2);
554 if (t == boolean_true_node)
557 /* If VAL1 is different than VAL2, return +2. */
558 t = fold_binary (NE_EXPR, boolean_type_node, val1, val2);
559 if (t == boolean_true_node)
567 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
568 0 if VAL is not inside VR,
569 -2 if we cannot tell either way.
571 FIXME, the current semantics of this functions are a bit quirky
572 when taken in the context of VRP. In here we do not care
573 about VR's type. If VR is the anti-range ~[3, 5] the call
574 value_inside_range (4, VR) will return 1.
576 This is counter-intuitive in a strict sense, but the callers
577 currently expect this. They are calling the function
578 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
579 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
582 This also applies to value_ranges_intersect_p and
583 range_includes_zero_p. The semantics of VR_RANGE and
584 VR_ANTI_RANGE should be encoded here, but that also means
585 adapting the users of these functions to the new semantics. */
588 value_inside_range (tree val, value_range_t *vr)
592 cmp1 = compare_values (val, vr->min);
593 if (cmp1 == -2 || cmp1 == 2)
596 cmp2 = compare_values (val, vr->max);
597 if (cmp2 == -2 || cmp2 == 2)
600 return (cmp1 == 0 || cmp1 == 1) && (cmp2 == -1 || cmp2 == 0);
604 /* Return true if value ranges VR0 and VR1 have a non-empty
608 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
610 return (value_inside_range (vr1->min, vr0) == 1
611 || value_inside_range (vr1->max, vr0) == 1
612 || value_inside_range (vr0->min, vr1) == 1
613 || value_inside_range (vr0->max, vr1) == 1);
617 /* Return true if VR includes the value zero, false otherwise. FIXME,
618 currently this will return false for an anti-range like ~[-4, 3].
619 This will be wrong when the semantics of value_inside_range are
620 modified (currently the users of this function expect these
624 range_includes_zero_p (value_range_t *vr)
628 gcc_assert (vr->type != VR_UNDEFINED
629 && vr->type != VR_VARYING
630 && !symbolic_range_p (vr));
632 zero = build_int_cst (TREE_TYPE (vr->min), 0);
633 return (value_inside_range (zero, vr) == 1);
637 /* When extracting ranges from X_i = ASSERT_EXPR <Y_j, pred>, we will
638 initially consider X_i and Y_j equivalent, so the equivalence set
639 of Y_j is added to the equivalence set of X_i. However, it is
640 possible to have a chain of ASSERT_EXPRs whose predicates are
641 actually incompatible. This is usually the result of nesting of
642 contradictory if-then-else statements. For instance, in PR 24670:
644 count_4 has range [-INF, 63]
648 count_19 = ASSERT_EXPR <count_4, count_4 != 0>
651 count_18 = ASSERT_EXPR <count_19, count_19 > 63>
657 Notice that 'if (count_19 > 63)' is trivially false and will be
658 folded out at the end. However, during propagation, the flowgraph
659 is not cleaned up and so, VRP will evaluate predicates more
660 predicates than necessary, so it must support these
661 inconsistencies. The problem here is that because of the chaining
662 of ASSERT_EXPRs, the equivalency set for count_18 includes count_4.
663 Since count_4 has an incompatible range, we ICE when evaluating the
664 ranges in the equivalency set. So, we need to remove count_4 from
668 fix_equivalence_set (value_range_t *vr_p)
672 bitmap e = vr_p->equiv;
673 bitmap to_remove = BITMAP_ALLOC (NULL);
675 /* Only detect inconsistencies on numeric ranges. */
676 if (vr_p->type == VR_VARYING
677 || vr_p->type == VR_UNDEFINED
678 || symbolic_range_p (vr_p))
681 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
683 value_range_t *equiv_vr = vr_value[i];
685 if (equiv_vr->type == VR_VARYING
686 || equiv_vr->type == VR_UNDEFINED
687 || symbolic_range_p (equiv_vr))
690 if (equiv_vr->type == VR_RANGE
691 && vr_p->type == VR_RANGE
692 && !value_ranges_intersect_p (vr_p, equiv_vr))
693 bitmap_set_bit (to_remove, i);
694 else if ((equiv_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
695 || (equiv_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
697 /* A range and an anti-range have an empty intersection if
698 their end points are the same. FIXME,
699 value_ranges_intersect_p should handle this
701 if (compare_values (equiv_vr->min, vr_p->min) == 0
702 && compare_values (equiv_vr->max, vr_p->max) == 0)
703 bitmap_set_bit (to_remove, i);
707 bitmap_and_compl_into (vr_p->equiv, to_remove);
708 BITMAP_FREE (to_remove);
712 /* Extract value range information from an ASSERT_EXPR EXPR and store
716 extract_range_from_assert (value_range_t *vr_p, tree expr)
718 tree var, cond, limit, min, max, type;
719 value_range_t *var_vr, *limit_vr;
720 enum tree_code cond_code;
722 var = ASSERT_EXPR_VAR (expr);
723 cond = ASSERT_EXPR_COND (expr);
725 gcc_assert (COMPARISON_CLASS_P (cond));
727 /* Find VAR in the ASSERT_EXPR conditional. */
728 if (var == TREE_OPERAND (cond, 0))
730 /* If the predicate is of the form VAR COMP LIMIT, then we just
731 take LIMIT from the RHS and use the same comparison code. */
732 limit = TREE_OPERAND (cond, 1);
733 cond_code = TREE_CODE (cond);
737 /* If the predicate is of the form LIMIT COMP VAR, then we need
738 to flip around the comparison code to create the proper range
740 limit = TREE_OPERAND (cond, 0);
741 cond_code = swap_tree_comparison (TREE_CODE (cond));
744 type = TREE_TYPE (limit);
745 gcc_assert (limit != var);
747 /* For pointer arithmetic, we only keep track of pointer equality
749 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
751 set_value_range_to_varying (vr_p);
755 /* If LIMIT is another SSA name and LIMIT has a range of its own,
756 try to use LIMIT's range to avoid creating symbolic ranges
758 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
760 /* LIMIT's range is only interesting if it has any useful information. */
762 && (limit_vr->type == VR_UNDEFINED
763 || limit_vr->type == VR_VARYING
764 || symbolic_range_p (limit_vr)))
767 /* Special handling for integral types with super-types. Some FEs
768 construct integral types derived from other types and restrict
769 the range of values these new types may take.
771 It may happen that LIMIT is actually smaller than TYPE's minimum
772 value. For instance, the Ada FE is generating code like this
775 D.1480_32 = nam_30 - 300000361;
776 if (D.1480_32 <= 1) goto <L112>; else goto <L52>;
778 D.1480_94 = ASSERT_EXPR <D.1480_32, D.1480_32 <= 1>;
780 All the names are of type types__name_id___XDLU_300000000__399999999
781 which has min == 300000000 and max == 399999999. This means that
782 the ASSERT_EXPR would try to create the range [3000000, 1] which
785 The fact that the type specifies MIN and MAX values does not
786 automatically mean that every variable of that type will always
787 be within that range, so the predicate may well be true at run
788 time. If we had symbolic -INF and +INF values, we could
789 represent this range, but we currently represent -INF and +INF
790 using the type's min and max values.
792 So, the only sensible thing we can do for now is set the
793 resulting range to VR_VARYING. TODO, would having symbolic -INF
794 and +INF values be worth the trouble? */
795 if (TREE_CODE (limit) != SSA_NAME
796 && INTEGRAL_TYPE_P (type)
799 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
801 tree type_min = TYPE_MIN_VALUE (type);
802 int cmp = compare_values (limit, type_min);
804 /* For < or <= comparisons, if LIMIT is smaller than
805 TYPE_MIN, set the range to VR_VARYING. */
806 if (cmp == -1 || cmp == 0)
808 set_value_range_to_varying (vr_p);
812 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
814 tree type_max = TYPE_MIN_VALUE (type);
815 int cmp = compare_values (limit, type_max);
817 /* For > or >= comparisons, if LIMIT is bigger than
818 TYPE_MAX, set the range to VR_VARYING. */
819 if (cmp == 1 || cmp == 0)
821 set_value_range_to_varying (vr_p);
827 /* Initially, the new range has the same set of equivalences of
828 VAR's range. This will be revised before returning the final
829 value. Since assertions may be chained via mutually exclusive
830 predicates, we will need to trim the set of equivalences before
832 gcc_assert (vr_p->equiv == NULL);
833 vr_p->equiv = BITMAP_ALLOC (NULL);
834 add_equivalence (vr_p->equiv, var);
836 /* Extract a new range based on the asserted comparison for VAR and
837 LIMIT's value range. Notice that if LIMIT has an anti-range, we
838 will only use it for equality comparisons (EQ_EXPR). For any
839 other kind of assertion, we cannot derive a range from LIMIT's
840 anti-range that can be used to describe the new range. For
841 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
842 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
843 no single range for x_2 that could describe LE_EXPR, so we might
844 as well build the range [b_4, +INF] for it. */
845 if (cond_code == EQ_EXPR)
847 enum value_range_type range_type;
851 range_type = limit_vr->type;
857 range_type = VR_RANGE;
862 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
864 /* When asserting the equality VAR == LIMIT and LIMIT is another
865 SSA name, the new range will also inherit the equivalence set
867 if (TREE_CODE (limit) == SSA_NAME)
868 add_equivalence (vr_p->equiv, limit);
870 else if (cond_code == NE_EXPR)
872 /* As described above, when LIMIT's range is an anti-range and
873 this assertion is an inequality (NE_EXPR), then we cannot
874 derive anything from the anti-range. For instance, if
875 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
876 not imply that VAR's range is [0, 0]. So, in the case of
877 anti-ranges, we just assert the inequality using LIMIT and
880 If LIMIT_VR is a range, we can only use it to build a new
881 anti-range if LIMIT_VR is a single-valued range. For
882 instance, if LIMIT_VR is [0, 1], the predicate
883 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
884 Rather, it means that for value 0 VAR should be ~[0, 0]
885 and for value 1, VAR should be ~[1, 1]. We cannot
886 represent these ranges.
888 The only situation in which we can build a valid
889 anti-range is when LIMIT_VR is a single-valued range
890 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
891 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
893 && limit_vr->type == VR_RANGE
894 && compare_values (limit_vr->min, limit_vr->max) == 0)
901 /* In any other case, we cannot use LIMIT's range to build a
906 /* If MIN and MAX cover the whole range for their type, then
907 just use the original LIMIT. */
908 if (INTEGRAL_TYPE_P (type)
909 && min == TYPE_MIN_VALUE (type)
910 && max == TYPE_MAX_VALUE (type))
913 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
915 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
917 min = TYPE_MIN_VALUE (type);
919 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
923 /* If LIMIT_VR is of the form [N1, N2], we need to build the
924 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
929 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
930 if (cond_code == LT_EXPR)
932 tree one = build_int_cst (type, 1);
933 max = fold_build2 (MINUS_EXPR, type, max, one);
936 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
938 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
940 max = TYPE_MAX_VALUE (type);
942 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
946 /* If LIMIT_VR is of the form [N1, N2], we need to build the
947 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
952 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
953 if (cond_code == GT_EXPR)
955 tree one = build_int_cst (type, 1);
956 min = fold_build2 (PLUS_EXPR, type, min, one);
959 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
964 /* If VAR already had a known range, it may happen that the new
965 range we have computed and VAR's range are not compatible. For
969 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
971 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
973 While the above comes from a faulty program, it will cause an ICE
974 later because p_8 and p_6 will have incompatible ranges and at
975 the same time will be considered equivalent. A similar situation
979 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
981 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
983 Again i_6 and i_7 will have incompatible ranges. It would be
984 pointless to try and do anything with i_7's range because
985 anything dominated by 'if (i_5 < 5)' will be optimized away.
986 Note, due to the wa in which simulation proceeds, the statement
987 i_7 = ASSERT_EXPR <...> we would never be visited because the
988 conditional 'if (i_5 < 5)' always evaluates to false. However,
989 this extra check does not hurt and may protect against future
990 changes to VRP that may get into a situation similar to the
991 NULL pointer dereference example.
993 Note that these compatibility tests are only needed when dealing
994 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
995 are both anti-ranges, they will always be compatible, because two
996 anti-ranges will always have a non-empty intersection. */
998 var_vr = get_value_range (var);
1000 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1001 ranges or anti-ranges. */
1002 if (vr_p->type == VR_VARYING
1003 || vr_p->type == VR_UNDEFINED
1004 || var_vr->type == VR_VARYING
1005 || var_vr->type == VR_UNDEFINED
1006 || symbolic_range_p (vr_p)
1007 || symbolic_range_p (var_vr))
1010 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
1012 /* If the two ranges have a non-empty intersection, we can
1013 refine the resulting range. Since the assert expression
1014 creates an equivalency and at the same time it asserts a
1015 predicate, we can take the intersection of the two ranges to
1016 get better precision. */
1017 if (value_ranges_intersect_p (var_vr, vr_p))
1019 /* Use the larger of the two minimums. */
1020 if (compare_values (vr_p->min, var_vr->min) == -1)
1025 /* Use the smaller of the two maximums. */
1026 if (compare_values (vr_p->max, var_vr->max) == 1)
1031 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
1035 /* The two ranges do not intersect, set the new range to
1036 VARYING, because we will not be able to do anything
1037 meaningful with it. */
1038 set_value_range_to_varying (vr_p);
1041 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
1042 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
1044 /* A range and an anti-range will cancel each other only if
1045 their ends are the same. For instance, in the example above,
1046 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1047 so VR_P should be set to VR_VARYING. */
1048 if (compare_values (var_vr->min, vr_p->min) == 0
1049 && compare_values (var_vr->max, vr_p->max) == 0)
1050 set_value_range_to_varying (vr_p);
1053 /* Remove names from the equivalence set that have ranges
1054 incompatible with VR_P. */
1056 fix_equivalence_set (vr_p);
1060 /* Extract range information from SSA name VAR and store it in VR. If
1061 VAR has an interesting range, use it. Otherwise, create the
1062 range [VAR, VAR] and return it. This is useful in situations where
1063 we may have conditionals testing values of VARYING names. For
1070 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1074 extract_range_from_ssa_name (value_range_t *vr, tree var)
1076 value_range_t *var_vr = get_value_range (var);
1078 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
1079 copy_value_range (vr, var_vr);
1081 set_value_range (vr, VR_RANGE, var, var, NULL);
1083 add_equivalence (vr->equiv, var);
1087 /* Wrapper around int_const_binop. If the operation overflows and we
1088 are not using wrapping arithmetic, then adjust the result to be
1089 -INF or +INF depending on CODE, VAL1 and VAL2. */
1092 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
1097 return int_const_binop (code, val1, val2, 0);
1099 /* If we are not using wrapping arithmetic, operate symbolically
1100 on -INF and +INF. */
1101 res = int_const_binop (code, val1, val2, 0);
1103 if (TYPE_UNSIGNED (TREE_TYPE (val1)))
1105 int checkz = compare_values (res, val1);
1107 /* Ensure that res = val1 + val2 >= val1
1108 or that res = val1 - val2 <= val1. */
1109 if ((code == PLUS_EXPR && !(checkz == 1 || checkz == 0))
1110 || (code == MINUS_EXPR && !(checkz == 0 || checkz == -1)))
1112 res = copy_node (res);
1113 TREE_OVERFLOW (res) = 1;
1116 /* If the operation overflowed but neither VAL1 nor VAL2 are
1117 overflown, return -INF or +INF depending on the operation
1118 and the combination of signs of the operands. */
1119 else if (TREE_OVERFLOW (res)
1120 && !TREE_OVERFLOW (val1)
1121 && !TREE_OVERFLOW (val2))
1123 int sgn1 = tree_int_cst_sgn (val1);
1124 int sgn2 = tree_int_cst_sgn (val2);
1126 /* Notice that we only need to handle the restricted set of
1127 operations handled by extract_range_from_binary_expr.
1128 Among them, only multiplication, addition and subtraction
1129 can yield overflow without overflown operands because we
1130 are working with integral types only... except in the
1131 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1132 for division too. */
1134 /* For multiplication, the sign of the overflow is given
1135 by the comparison of the signs of the operands. */
1136 if ((code == MULT_EXPR && sgn1 == sgn2)
1137 /* For addition, the operands must be of the same sign
1138 to yield an overflow. Its sign is therefore that
1139 of one of the operands, for example the first. */
1140 || (code == PLUS_EXPR && sgn1 > 0)
1141 /* For subtraction, the operands must be of different
1142 signs to yield an overflow. Its sign is therefore
1143 that of the first operand or the opposite of that
1144 of the second operand. A first operand of 0 counts
1145 as positive here, for the corner case 0 - (-INF),
1146 which overflows, but must yield +INF. */
1147 || (code == MINUS_EXPR && sgn1 >= 0)
1148 /* For division, the only case is -INF / -1 = +INF. */
1149 || code == TRUNC_DIV_EXPR
1150 || code == FLOOR_DIV_EXPR
1151 || code == CEIL_DIV_EXPR
1152 || code == EXACT_DIV_EXPR
1153 || code == ROUND_DIV_EXPR)
1154 return TYPE_MAX_VALUE (TREE_TYPE (res));
1156 return TYPE_MIN_VALUE (TREE_TYPE (res));
1163 /* Extract range information from a binary expression EXPR based on
1164 the ranges of each of its operands and the expression code. */
1167 extract_range_from_binary_expr (value_range_t *vr, tree expr)
1169 enum tree_code code = TREE_CODE (expr);
1170 enum value_range_type type;
1171 tree op0, op1, min, max;
1173 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1174 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1176 /* Not all binary expressions can be applied to ranges in a
1177 meaningful way. Handle only arithmetic operations. */
1178 if (code != PLUS_EXPR
1179 && code != MINUS_EXPR
1180 && code != MULT_EXPR
1181 && code != TRUNC_DIV_EXPR
1182 && code != FLOOR_DIV_EXPR
1183 && code != CEIL_DIV_EXPR
1184 && code != EXACT_DIV_EXPR
1185 && code != ROUND_DIV_EXPR
1188 && code != BIT_AND_EXPR
1189 && code != TRUTH_ANDIF_EXPR
1190 && code != TRUTH_ORIF_EXPR
1191 && code != TRUTH_AND_EXPR
1192 && code != TRUTH_OR_EXPR
1193 && code != TRUTH_XOR_EXPR)
1195 set_value_range_to_varying (vr);
1199 /* Get value ranges for each operand. For constant operands, create
1200 a new value range with the operand to simplify processing. */
1201 op0 = TREE_OPERAND (expr, 0);
1202 if (TREE_CODE (op0) == SSA_NAME)
1203 vr0 = *(get_value_range (op0));
1204 else if (is_gimple_min_invariant (op0))
1205 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1207 set_value_range_to_varying (&vr0);
1209 op1 = TREE_OPERAND (expr, 1);
1210 if (TREE_CODE (op1) == SSA_NAME)
1211 vr1 = *(get_value_range (op1));
1212 else if (is_gimple_min_invariant (op1))
1213 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1215 set_value_range_to_varying (&vr1);
1217 /* If either range is UNDEFINED, so is the result. */
1218 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1220 set_value_range_to_undefined (vr);
1224 /* The type of the resulting value range defaults to VR0.TYPE. */
1227 /* Refuse to operate on VARYING ranges, ranges of different kinds
1228 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1229 because we may be able to derive a useful range even if one of
1230 the operands is VR_VARYING or symbolic range. TODO, we may be
1231 able to derive anti-ranges in some cases. */
1232 if (code != BIT_AND_EXPR
1233 && code != TRUTH_AND_EXPR
1234 && code != TRUTH_OR_EXPR
1235 && (vr0.type == VR_VARYING
1236 || vr1.type == VR_VARYING
1237 || vr0.type != vr1.type
1238 || symbolic_range_p (&vr0)
1239 || symbolic_range_p (&vr1)))
1241 set_value_range_to_varying (vr);
1245 /* Now evaluate the expression to determine the new range. */
1246 if (POINTER_TYPE_P (TREE_TYPE (expr))
1247 || POINTER_TYPE_P (TREE_TYPE (op0))
1248 || POINTER_TYPE_P (TREE_TYPE (op1)))
1250 /* For pointer types, we are really only interested in asserting
1251 whether the expression evaluates to non-NULL. FIXME, we used
1252 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1253 ivopts is generating expressions with pointer multiplication
1255 if (code == PLUS_EXPR)
1257 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1258 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1259 else if (range_is_null (&vr0) && range_is_null (&vr1))
1260 set_value_range_to_null (vr, TREE_TYPE (expr));
1262 set_value_range_to_varying (vr);
1266 /* Subtracting from a pointer, may yield 0, so just drop the
1267 resulting range to varying. */
1268 set_value_range_to_varying (vr);
1274 /* For integer ranges, apply the operation to each end of the
1275 range and see what we end up with. */
1276 if (code == TRUTH_ANDIF_EXPR
1277 || code == TRUTH_ORIF_EXPR
1278 || code == TRUTH_AND_EXPR
1279 || code == TRUTH_OR_EXPR
1280 || code == TRUTH_XOR_EXPR)
1282 /* If one of the operands is zero, we know that the whole
1283 expression evaluates zero. */
1284 if (code == TRUTH_AND_EXPR
1285 && ((vr0.type == VR_RANGE
1286 && integer_zerop (vr0.min)
1287 && integer_zerop (vr0.max))
1288 || (vr1.type == VR_RANGE
1289 && integer_zerop (vr1.min)
1290 && integer_zerop (vr1.max))))
1293 min = max = build_int_cst (TREE_TYPE (expr), 0);
1295 /* If one of the operands is one, we know that the whole
1296 expression evaluates one. */
1297 else if (code == TRUTH_OR_EXPR
1298 && ((vr0.type == VR_RANGE
1299 && integer_onep (vr0.min)
1300 && integer_onep (vr0.max))
1301 || (vr1.type == VR_RANGE
1302 && integer_onep (vr1.min)
1303 && integer_onep (vr1.max))))
1306 min = max = build_int_cst (TREE_TYPE (expr), 1);
1308 else if (vr0.type != VR_VARYING
1309 && vr1.type != VR_VARYING
1310 && vr0.type == vr1.type
1311 && !symbolic_range_p (&vr0)
1312 && !symbolic_range_p (&vr1))
1314 /* Boolean expressions cannot be folded with int_const_binop. */
1315 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1316 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1320 set_value_range_to_varying (vr);
1324 else if (code == PLUS_EXPR
1326 || code == MAX_EXPR)
1328 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1329 VR_VARYING. It would take more effort to compute a precise
1330 range for such a case. For example, if we have op0 == 1 and
1331 op1 == -1 with their ranges both being ~[0,0], we would have
1332 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1333 Note that we are guaranteed to have vr0.type == vr1.type at
1335 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1337 set_value_range_to_varying (vr);
1341 /* For operations that make the resulting range directly
1342 proportional to the original ranges, apply the operation to
1343 the same end of each range. */
1344 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1345 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1347 else if (code == MULT_EXPR
1348 || code == TRUNC_DIV_EXPR
1349 || code == FLOOR_DIV_EXPR
1350 || code == CEIL_DIV_EXPR
1351 || code == EXACT_DIV_EXPR
1352 || code == ROUND_DIV_EXPR)
1357 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1358 drop to VR_VARYING. It would take more effort to compute a
1359 precise range for such a case. For example, if we have
1360 op0 == 65536 and op1 == 65536 with their ranges both being
1361 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1362 we cannot claim that the product is in ~[0,0]. Note that we
1363 are guaranteed to have vr0.type == vr1.type at this
1365 if (code == MULT_EXPR
1366 && vr0.type == VR_ANTI_RANGE
1367 && (flag_wrapv || TYPE_UNSIGNED (TREE_TYPE (op0))))
1369 set_value_range_to_varying (vr);
1373 /* Multiplications and divisions are a bit tricky to handle,
1374 depending on the mix of signs we have in the two ranges, we
1375 need to operate on different values to get the minimum and
1376 maximum values for the new range. One approach is to figure
1377 out all the variations of range combinations and do the
1380 However, this involves several calls to compare_values and it
1381 is pretty convoluted. It's simpler to do the 4 operations
1382 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1383 MAX1) and then figure the smallest and largest values to form
1386 /* Divisions by zero result in a VARYING value. */
1387 if (code != MULT_EXPR
1388 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1390 set_value_range_to_varying (vr);
1394 /* Compute the 4 cross operations. */
1395 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1397 val[1] = (vr1.max != vr1.min)
1398 ? vrp_int_const_binop (code, vr0.min, vr1.max)
1401 val[2] = (vr0.max != vr0.min)
1402 ? vrp_int_const_binop (code, vr0.max, vr1.min)
1405 val[3] = (vr0.min != vr0.max && vr1.min != vr1.max)
1406 ? vrp_int_const_binop (code, vr0.max, vr1.max)
1409 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1413 for (i = 1; i < 4; i++)
1415 if (TREE_OVERFLOW (min) || TREE_OVERFLOW (max))
1420 if (TREE_OVERFLOW (val[i]))
1422 /* If we found an overflowed value, set MIN and MAX
1423 to it so that we set the resulting range to
1429 if (compare_values (val[i], min) == -1)
1432 if (compare_values (val[i], max) == 1)
1437 else if (code == MINUS_EXPR)
1439 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1440 VR_VARYING. It would take more effort to compute a precise
1441 range for such a case. For example, if we have op0 == 1 and
1442 op1 == 1 with their ranges both being ~[0,0], we would have
1443 op0 - op1 == 0, so we cannot claim that the difference is in
1444 ~[0,0]. Note that we are guaranteed to have
1445 vr0.type == vr1.type at this point. */
1446 if (vr0.type == VR_ANTI_RANGE)
1448 set_value_range_to_varying (vr);
1452 /* For MINUS_EXPR, apply the operation to the opposite ends of
1454 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1455 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1457 else if (code == BIT_AND_EXPR)
1459 if (vr0.type == VR_RANGE
1460 && vr0.min == vr0.max
1461 && tree_expr_nonnegative_p (vr0.max)
1462 && TREE_CODE (vr0.max) == INTEGER_CST)
1464 min = build_int_cst (TREE_TYPE (expr), 0);
1467 else if (vr1.type == VR_RANGE
1468 && vr1.min == vr1.max
1469 && tree_expr_nonnegative_p (vr1.max)
1470 && TREE_CODE (vr1.max) == INTEGER_CST)
1473 min = build_int_cst (TREE_TYPE (expr), 0);
1478 set_value_range_to_varying (vr);
1485 /* If either MIN or MAX overflowed, then set the resulting range to
1487 if (TREE_OVERFLOW (min) || TREE_OVERFLOW (max))
1489 set_value_range_to_varying (vr);
1493 cmp = compare_values (min, max);
1494 if (cmp == -2 || cmp == 1)
1496 /* If the new range has its limits swapped around (MIN > MAX),
1497 then the operation caused one of them to wrap around, mark
1498 the new range VARYING. */
1499 set_value_range_to_varying (vr);
1502 set_value_range (vr, type, min, max, NULL);
1506 /* Extract range information from a unary expression EXPR based on
1507 the range of its operand and the expression code. */
1510 extract_range_from_unary_expr (value_range_t *vr, tree expr)
1512 enum tree_code code = TREE_CODE (expr);
1515 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1517 /* Refuse to operate on certain unary expressions for which we
1518 cannot easily determine a resulting range. */
1519 if (code == FIX_TRUNC_EXPR
1520 || code == FIX_CEIL_EXPR
1521 || code == FIX_FLOOR_EXPR
1522 || code == FIX_ROUND_EXPR
1523 || code == FLOAT_EXPR
1524 || code == BIT_NOT_EXPR
1525 || code == NON_LVALUE_EXPR
1526 || code == CONJ_EXPR)
1528 set_value_range_to_varying (vr);
1532 /* Get value ranges for the operand. For constant operands, create
1533 a new value range with the operand to simplify processing. */
1534 op0 = TREE_OPERAND (expr, 0);
1535 if (TREE_CODE (op0) == SSA_NAME)
1536 vr0 = *(get_value_range (op0));
1537 else if (is_gimple_min_invariant (op0))
1538 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1540 set_value_range_to_varying (&vr0);
1542 /* If VR0 is UNDEFINED, so is the result. */
1543 if (vr0.type == VR_UNDEFINED)
1545 set_value_range_to_undefined (vr);
1549 /* Refuse to operate on varying and symbolic ranges. Also, if the
1550 operand is neither a pointer nor an integral type, set the
1551 resulting range to VARYING. TODO, in some cases we may be able
1552 to derive anti-ranges (like nonzero values). */
1553 if (vr0.type == VR_VARYING
1554 || (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
1555 && !POINTER_TYPE_P (TREE_TYPE (op0)))
1556 || symbolic_range_p (&vr0))
1558 set_value_range_to_varying (vr);
1562 /* If the expression involves pointers, we are only interested in
1563 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1564 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
1566 if (range_is_nonnull (&vr0) || tree_expr_nonzero_p (expr))
1567 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1568 else if (range_is_null (&vr0))
1569 set_value_range_to_null (vr, TREE_TYPE (expr));
1571 set_value_range_to_varying (vr);
1576 /* Handle unary expressions on integer ranges. */
1577 if (code == NOP_EXPR || code == CONVERT_EXPR)
1579 tree inner_type = TREE_TYPE (op0);
1580 tree outer_type = TREE_TYPE (expr);
1582 /* If VR0 represents a simple range, then try to convert
1583 the min and max values for the range to the same type
1584 as OUTER_TYPE. If the results compare equal to VR0's
1585 min and max values and the new min is still less than
1586 or equal to the new max, then we can safely use the newly
1587 computed range for EXPR. This allows us to compute
1588 accurate ranges through many casts. */
1589 if (vr0.type == VR_RANGE)
1591 tree new_min, new_max;
1593 /* Convert VR0's min/max to OUTER_TYPE. */
1594 new_min = fold_convert (outer_type, vr0.min);
1595 new_max = fold_convert (outer_type, vr0.max);
1597 /* Verify the new min/max values are gimple values and
1598 that they compare equal to VR0's min/max values. */
1599 if (is_gimple_val (new_min)
1600 && is_gimple_val (new_max)
1601 && tree_int_cst_equal (new_min, vr0.min)
1602 && tree_int_cst_equal (new_max, vr0.max)
1603 && compare_values (new_min, new_max) <= 0
1604 && compare_values (new_min, new_max) >= -1)
1606 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
1611 /* When converting types of different sizes, set the result to
1612 VARYING. Things like sign extensions and precision loss may
1613 change the range. For instance, if x_3 is of type 'long long
1614 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1615 is impossible to know at compile time whether y_5 will be
1617 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
1618 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
1620 set_value_range_to_varying (vr);
1625 /* Apply the operation to each end of the range and see what we end
1627 if (code == NEGATE_EXPR
1628 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1630 /* NEGATE_EXPR flips the range around. */
1631 min = (vr0.max == TYPE_MAX_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
1632 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1633 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1635 max = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
1636 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1637 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1639 else if (code == ABS_EXPR
1640 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1642 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1645 && ((vr0.type == VR_RANGE
1646 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1647 || (vr0.type == VR_ANTI_RANGE
1648 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
1649 && !range_includes_zero_p (&vr0))))
1651 set_value_range_to_varying (vr);
1655 /* ABS_EXPR may flip the range around, if the original range
1656 included negative values. */
1657 min = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1658 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1659 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1661 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1663 cmp = compare_values (min, max);
1665 /* If a VR_ANTI_RANGEs contains zero, then we have
1666 ~[-INF, min(MIN, MAX)]. */
1667 if (vr0.type == VR_ANTI_RANGE)
1669 if (range_includes_zero_p (&vr0))
1671 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
1673 /* Take the lower of the two values. */
1677 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1678 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1679 flag_wrapv is set and the original anti-range doesn't include
1680 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1681 min = (flag_wrapv && vr0.min != type_min_value
1682 ? int_const_binop (PLUS_EXPR,
1684 integer_one_node, 0)
1689 /* All else has failed, so create the range [0, INF], even for
1690 flag_wrapv since TYPE_MIN_VALUE is in the original
1692 vr0.type = VR_RANGE;
1693 min = build_int_cst (TREE_TYPE (expr), 0);
1694 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
1698 /* If the range contains zero then we know that the minimum value in the
1699 range will be zero. */
1700 else if (range_includes_zero_p (&vr0))
1704 min = build_int_cst (TREE_TYPE (expr), 0);
1708 /* If the range was reversed, swap MIN and MAX. */
1719 /* Otherwise, operate on each end of the range. */
1720 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1721 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1724 cmp = compare_values (min, max);
1725 if (cmp == -2 || cmp == 1)
1727 /* If the new range has its limits swapped around (MIN > MAX),
1728 then the operation caused one of them to wrap around, mark
1729 the new range VARYING. */
1730 set_value_range_to_varying (vr);
1733 set_value_range (vr, vr0.type, min, max, NULL);
1737 /* Extract range information from a comparison expression EXPR based
1738 on the range of its operand and the expression code. */
1741 extract_range_from_comparison (value_range_t *vr, tree expr)
1743 tree val = vrp_evaluate_conditional (expr, false);
1746 /* Since this expression was found on the RHS of an assignment,
1747 its type may be different from _Bool. Convert VAL to EXPR's
1749 val = fold_convert (TREE_TYPE (expr), val);
1750 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
1753 set_value_range_to_varying (vr);
1757 /* Try to compute a useful range out of expression EXPR and store it
1761 extract_range_from_expr (value_range_t *vr, tree expr)
1763 enum tree_code code = TREE_CODE (expr);
1765 if (code == ASSERT_EXPR)
1766 extract_range_from_assert (vr, expr);
1767 else if (code == SSA_NAME)
1768 extract_range_from_ssa_name (vr, expr);
1769 else if (TREE_CODE_CLASS (code) == tcc_binary
1770 || code == TRUTH_ANDIF_EXPR
1771 || code == TRUTH_ORIF_EXPR
1772 || code == TRUTH_AND_EXPR
1773 || code == TRUTH_OR_EXPR
1774 || code == TRUTH_XOR_EXPR)
1775 extract_range_from_binary_expr (vr, expr);
1776 else if (TREE_CODE_CLASS (code) == tcc_unary)
1777 extract_range_from_unary_expr (vr, expr);
1778 else if (TREE_CODE_CLASS (code) == tcc_comparison)
1779 extract_range_from_comparison (vr, expr);
1780 else if (is_gimple_min_invariant (expr))
1781 set_value_range (vr, VR_RANGE, expr, expr, NULL);
1782 else if (vrp_expr_computes_nonzero (expr))
1783 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1785 set_value_range_to_varying (vr);
1788 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1789 would be profitable to adjust VR using scalar evolution information
1790 for VAR. If so, update VR with the new limits. */
1793 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
1796 tree init, step, chrec;
1797 bool init_is_max, unknown_max;
1799 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1800 better opportunities than a regular range, but I'm not sure. */
1801 if (vr->type == VR_ANTI_RANGE)
1804 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
1805 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
1808 init = initial_condition_in_loop_num (chrec, loop->num);
1809 step = evolution_part_in_loop_num (chrec, loop->num);
1811 /* If STEP is symbolic, we can't know whether INIT will be the
1812 minimum or maximum value in the range. */
1813 if (step == NULL_TREE
1814 || !is_gimple_min_invariant (step))
1817 /* Do not adjust ranges when chrec may wrap. */
1818 if (scev_probably_wraps_p (chrec_type (chrec), init, step, stmt,
1819 cfg_loops->parray[CHREC_VARIABLE (chrec)],
1820 &init_is_max, &unknown_max)
1824 if (!POINTER_TYPE_P (TREE_TYPE (init))
1825 && (vr->type == VR_VARYING || vr->type == VR_UNDEFINED))
1827 /* For VARYING or UNDEFINED ranges, just about anything we get
1828 from scalar evolutions should be better. */
1830 set_value_range (vr, VR_RANGE, TYPE_MIN_VALUE (TREE_TYPE (init)),
1833 set_value_range (vr, VR_RANGE, init, TYPE_MAX_VALUE (TREE_TYPE (init)),
1836 else if (vr->type == VR_RANGE)
1843 /* INIT is the maximum value. If INIT is lower than VR->MAX
1844 but no smaller than VR->MIN, set VR->MAX to INIT. */
1845 if (compare_values (init, max) == -1)
1849 /* If we just created an invalid range with the minimum
1850 greater than the maximum, take the minimum all the
1852 if (compare_values (min, max) == 1)
1853 min = TYPE_MIN_VALUE (TREE_TYPE (min));
1858 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
1859 if (compare_values (init, min) == 1)
1863 /* If we just created an invalid range with the minimum
1864 greater than the maximum, take the maximum all the
1866 if (compare_values (min, max) == 1)
1867 max = TYPE_MAX_VALUE (TREE_TYPE (max));
1871 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
1876 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
1878 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
1879 all the values in the ranges.
1881 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
1883 - Return NULL_TREE if it is not always possible to determine the
1884 value of the comparison. */
1888 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1)
1890 /* VARYING or UNDEFINED ranges cannot be compared. */
1891 if (vr0->type == VR_VARYING
1892 || vr0->type == VR_UNDEFINED
1893 || vr1->type == VR_VARYING
1894 || vr1->type == VR_UNDEFINED)
1897 /* Anti-ranges need to be handled separately. */
1898 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
1900 /* If both are anti-ranges, then we cannot compute any
1902 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
1905 /* These comparisons are never statically computable. */
1912 /* Equality can be computed only between a range and an
1913 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
1914 if (vr0->type == VR_RANGE)
1916 /* To simplify processing, make VR0 the anti-range. */
1917 value_range_t *tmp = vr0;
1922 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
1924 if (compare_values (vr0->min, vr1->min) == 0
1925 && compare_values (vr0->max, vr1->max) == 0)
1926 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
1931 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
1932 operands around and change the comparison code. */
1933 if (comp == GT_EXPR || comp == GE_EXPR)
1936 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
1942 if (comp == EQ_EXPR)
1944 /* Equality may only be computed if both ranges represent
1945 exactly one value. */
1946 if (compare_values (vr0->min, vr0->max) == 0
1947 && compare_values (vr1->min, vr1->max) == 0)
1949 int cmp_min = compare_values (vr0->min, vr1->min);
1950 int cmp_max = compare_values (vr0->max, vr1->max);
1951 if (cmp_min == 0 && cmp_max == 0)
1952 return boolean_true_node;
1953 else if (cmp_min != -2 && cmp_max != -2)
1954 return boolean_false_node;
1956 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
1957 else if (compare_values (vr0->min, vr1->max) == 1
1958 || compare_values (vr1->min, vr0->max) == 1)
1959 return boolean_false_node;
1963 else if (comp == NE_EXPR)
1967 /* If VR0 is completely to the left or completely to the right
1968 of VR1, they are always different. Notice that we need to
1969 make sure that both comparisons yield similar results to
1970 avoid comparing values that cannot be compared at
1972 cmp1 = compare_values (vr0->max, vr1->min);
1973 cmp2 = compare_values (vr0->min, vr1->max);
1974 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
1975 return boolean_true_node;
1977 /* If VR0 and VR1 represent a single value and are identical,
1979 else if (compare_values (vr0->min, vr0->max) == 0
1980 && compare_values (vr1->min, vr1->max) == 0
1981 && compare_values (vr0->min, vr1->min) == 0
1982 && compare_values (vr0->max, vr1->max) == 0)
1983 return boolean_false_node;
1985 /* Otherwise, they may or may not be different. */
1989 else if (comp == LT_EXPR || comp == LE_EXPR)
1993 /* If VR0 is to the left of VR1, return true. */
1994 tst = compare_values (vr0->max, vr1->min);
1995 if ((comp == LT_EXPR && tst == -1)
1996 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
1997 return boolean_true_node;
1999 /* If VR0 is to the right of VR1, return false. */
2000 tst = compare_values (vr0->min, vr1->max);
2001 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2002 || (comp == LE_EXPR && tst == 1))
2003 return boolean_false_node;
2005 /* Otherwise, we don't know. */
2013 /* Given a value range VR, a value VAL and a comparison code COMP, return
2014 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2015 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2016 always returns false. Return NULL_TREE if it is not always
2017 possible to determine the value of the comparison. */
2020 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val)
2022 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2025 /* Anti-ranges need to be handled separately. */
2026 if (vr->type == VR_ANTI_RANGE)
2028 /* For anti-ranges, the only predicates that we can compute at
2029 compile time are equality and inequality. */
2036 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2037 if (value_inside_range (val, vr) == 1)
2038 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2043 if (comp == EQ_EXPR)
2045 /* EQ_EXPR may only be computed if VR represents exactly
2047 if (compare_values (vr->min, vr->max) == 0)
2049 int cmp = compare_values (vr->min, val);
2051 return boolean_true_node;
2052 else if (cmp == -1 || cmp == 1 || cmp == 2)
2053 return boolean_false_node;
2055 else if (compare_values (val, vr->min) == -1
2056 || compare_values (vr->max, val) == -1)
2057 return boolean_false_node;
2061 else if (comp == NE_EXPR)
2063 /* If VAL is not inside VR, then they are always different. */
2064 if (compare_values (vr->max, val) == -1
2065 || compare_values (vr->min, val) == 1)
2066 return boolean_true_node;
2068 /* If VR represents exactly one value equal to VAL, then return
2070 if (compare_values (vr->min, vr->max) == 0
2071 && compare_values (vr->min, val) == 0)
2072 return boolean_false_node;
2074 /* Otherwise, they may or may not be different. */
2077 else if (comp == LT_EXPR || comp == LE_EXPR)
2081 /* If VR is to the left of VAL, return true. */
2082 tst = compare_values (vr->max, val);
2083 if ((comp == LT_EXPR && tst == -1)
2084 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2085 return boolean_true_node;
2087 /* If VR is to the right of VAL, return false. */
2088 tst = compare_values (vr->min, val);
2089 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2090 || (comp == LE_EXPR && tst == 1))
2091 return boolean_false_node;
2093 /* Otherwise, we don't know. */
2096 else if (comp == GT_EXPR || comp == GE_EXPR)
2100 /* If VR is to the right of VAL, return true. */
2101 tst = compare_values (vr->min, val);
2102 if ((comp == GT_EXPR && tst == 1)
2103 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
2104 return boolean_true_node;
2106 /* If VR is to the left of VAL, return false. */
2107 tst = compare_values (vr->max, val);
2108 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
2109 || (comp == GE_EXPR && tst == -1))
2110 return boolean_false_node;
2112 /* Otherwise, we don't know. */
2120 /* Debugging dumps. */
2122 void dump_value_range (FILE *, value_range_t *);
2123 void debug_value_range (value_range_t *);
2124 void dump_all_value_ranges (FILE *);
2125 void debug_all_value_ranges (void);
2126 void dump_vr_equiv (FILE *, bitmap);
2127 void debug_vr_equiv (bitmap);
2130 /* Dump value range VR to FILE. */
2133 dump_value_range (FILE *file, value_range_t *vr)
2136 fprintf (file, "[]");
2137 else if (vr->type == VR_UNDEFINED)
2138 fprintf (file, "UNDEFINED");
2139 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
2141 tree type = TREE_TYPE (vr->min);
2143 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
2145 if (INTEGRAL_TYPE_P (type)
2146 && !TYPE_UNSIGNED (type)
2147 && vr->min == TYPE_MIN_VALUE (type))
2148 fprintf (file, "-INF");
2150 print_generic_expr (file, vr->min, 0);
2152 fprintf (file, ", ");
2154 if (INTEGRAL_TYPE_P (type)
2155 && vr->max == TYPE_MAX_VALUE (type))
2156 fprintf (file, "+INF");
2158 print_generic_expr (file, vr->max, 0);
2160 fprintf (file, "]");
2167 fprintf (file, " EQUIVALENCES: { ");
2169 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
2171 print_generic_expr (file, ssa_name (i), 0);
2172 fprintf (file, " ");
2176 fprintf (file, "} (%u elements)", c);
2179 else if (vr->type == VR_VARYING)
2180 fprintf (file, "VARYING");
2182 fprintf (file, "INVALID RANGE");
2186 /* Dump value range VR to stderr. */
2189 debug_value_range (value_range_t *vr)
2191 dump_value_range (stderr, vr);
2195 /* Dump value ranges of all SSA_NAMEs to FILE. */
2198 dump_all_value_ranges (FILE *file)
2202 for (i = 0; i < num_ssa_names; i++)
2206 print_generic_expr (file, ssa_name (i), 0);
2207 fprintf (file, ": ");
2208 dump_value_range (file, vr_value[i]);
2209 fprintf (file, "\n");
2213 fprintf (file, "\n");
2217 /* Dump all value ranges to stderr. */
2220 debug_all_value_ranges (void)
2222 dump_all_value_ranges (stderr);
2226 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
2227 create a new SSA name N and return the assertion assignment
2228 'V = ASSERT_EXPR <V, V OP W>'. */
2231 build_assert_expr_for (tree cond, tree v)
2235 gcc_assert (TREE_CODE (v) == SSA_NAME);
2236 n = duplicate_ssa_name (v, NULL_TREE);
2238 if (COMPARISON_CLASS_P (cond))
2240 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
2241 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, a);
2243 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
2245 /* Given !V, build the assignment N = false. */
2246 tree op0 = TREE_OPERAND (cond, 0);
2247 gcc_assert (op0 == v);
2248 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_false_node);
2250 else if (TREE_CODE (cond) == SSA_NAME)
2252 /* Given V, build the assignment N = true. */
2253 gcc_assert (v == cond);
2254 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_true_node);
2259 SSA_NAME_DEF_STMT (n) = assertion;
2261 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
2262 operand of the ASSERT_EXPR. Register the new name and the old one
2263 in the replacement table so that we can fix the SSA web after
2264 adding all the ASSERT_EXPRs. */
2265 register_new_name_mapping (n, v);
2271 /* Return false if EXPR is a predicate expression involving floating
2275 fp_predicate (tree expr)
2277 return (COMPARISON_CLASS_P (expr)
2278 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
2282 /* If the range of values taken by OP can be inferred after STMT executes,
2283 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2284 describes the inferred range. Return true if a range could be
2288 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
2291 *comp_code_p = ERROR_MARK;
2293 /* Do not attempt to infer anything in names that flow through
2295 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
2298 /* Similarly, don't infer anything from statements that may throw
2300 if (tree_could_throw_p (stmt))
2303 /* If STMT is the last statement of a basic block with no
2304 successors, there is no point inferring anything about any of its
2305 operands. We would not be able to find a proper insertion point
2306 for the assertion, anyway. */
2307 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
2310 if (POINTER_TYPE_P (TREE_TYPE (op)))
2313 unsigned num_uses, num_derefs;
2315 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
2316 if (num_derefs > 0 && flag_delete_null_pointer_checks)
2318 /* We can only assume that a pointer dereference will yield
2319 non-NULL if -fdelete-null-pointer-checks is enabled. */
2320 *val_p = build_int_cst (TREE_TYPE (op), 0);
2321 *comp_code_p = NE_EXPR;
2330 void dump_asserts_for (FILE *, tree);
2331 void debug_asserts_for (tree);
2332 void dump_all_asserts (FILE *);
2333 void debug_all_asserts (void);
2335 /* Dump all the registered assertions for NAME to FILE. */
2338 dump_asserts_for (FILE *file, tree name)
2342 fprintf (file, "Assertions to be inserted for ");
2343 print_generic_expr (file, name, 0);
2344 fprintf (file, "\n");
2346 loc = asserts_for[SSA_NAME_VERSION (name)];
2349 fprintf (file, "\t");
2350 print_generic_expr (file, bsi_stmt (loc->si), 0);
2351 fprintf (file, "\n\tBB #%d", loc->bb->index);
2354 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
2355 loc->e->dest->index);
2356 dump_edge_info (file, loc->e, 0);
2358 fprintf (file, "\n\tPREDICATE: ");
2359 print_generic_expr (file, name, 0);
2360 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
2361 print_generic_expr (file, loc->val, 0);
2362 fprintf (file, "\n\n");
2366 fprintf (file, "\n");
2370 /* Dump all the registered assertions for NAME to stderr. */
2373 debug_asserts_for (tree name)
2375 dump_asserts_for (stderr, name);
2379 /* Dump all the registered assertions for all the names to FILE. */
2382 dump_all_asserts (FILE *file)
2387 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
2388 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2389 dump_asserts_for (file, ssa_name (i));
2390 fprintf (file, "\n");
2394 /* Dump all the registered assertions for all the names to stderr. */
2397 debug_all_asserts (void)
2399 dump_all_asserts (stderr);
2403 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2404 'NAME COMP_CODE VAL' at a location that dominates block BB or
2405 E->DEST, then register this location as a possible insertion point
2406 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2408 BB, E and SI provide the exact insertion point for the new
2409 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2410 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2411 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2412 must not be NULL. */
2415 register_new_assert_for (tree name,
2416 enum tree_code comp_code,
2420 block_stmt_iterator si)
2422 assert_locus_t n, loc, last_loc;
2424 basic_block dest_bb;
2426 #if defined ENABLE_CHECKING
2427 gcc_assert (bb == NULL || e == NULL);
2430 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
2431 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
2434 /* The new assertion A will be inserted at BB or E. We need to
2435 determine if the new location is dominated by a previously
2436 registered location for A. If we are doing an edge insertion,
2437 assume that A will be inserted at E->DEST. Note that this is not
2440 If E is a critical edge, it will be split. But even if E is
2441 split, the new block will dominate the same set of blocks that
2444 The reverse, however, is not true, blocks dominated by E->DEST
2445 will not be dominated by the new block created to split E. So,
2446 if the insertion location is on a critical edge, we will not use
2447 the new location to move another assertion previously registered
2448 at a block dominated by E->DEST. */
2449 dest_bb = (bb) ? bb : e->dest;
2451 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2452 VAL at a block dominating DEST_BB, then we don't need to insert a new
2453 one. Similarly, if the same assertion already exists at a block
2454 dominated by DEST_BB and the new location is not on a critical
2455 edge, then update the existing location for the assertion (i.e.,
2456 move the assertion up in the dominance tree).
2458 Note, this is implemented as a simple linked list because there
2459 should not be more than a handful of assertions registered per
2460 name. If this becomes a performance problem, a table hashed by
2461 COMP_CODE and VAL could be implemented. */
2462 loc = asserts_for[SSA_NAME_VERSION (name)];
2467 if (loc->comp_code == comp_code
2469 || operand_equal_p (loc->val, val, 0)))
2471 /* If the assertion NAME COMP_CODE VAL has already been
2472 registered at a basic block that dominates DEST_BB, then
2473 we don't need to insert the same assertion again. Note
2474 that we don't check strict dominance here to avoid
2475 replicating the same assertion inside the same basic
2476 block more than once (e.g., when a pointer is
2477 dereferenced several times inside a block).
2479 An exception to this rule are edge insertions. If the
2480 new assertion is to be inserted on edge E, then it will
2481 dominate all the other insertions that we may want to
2482 insert in DEST_BB. So, if we are doing an edge
2483 insertion, don't do this dominance check. */
2485 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
2488 /* Otherwise, if E is not a critical edge and DEST_BB
2489 dominates the existing location for the assertion, move
2490 the assertion up in the dominance tree by updating its
2491 location information. */
2492 if ((e == NULL || !EDGE_CRITICAL_P (e))
2493 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
2502 /* Update the last node of the list and move to the next one. */
2507 /* If we didn't find an assertion already registered for
2508 NAME COMP_CODE VAL, add a new one at the end of the list of
2509 assertions associated with NAME. */
2510 n = xmalloc (sizeof (*n));
2514 n->comp_code = comp_code;
2521 asserts_for[SSA_NAME_VERSION (name)] = n;
2523 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
2527 /* Try to register an edge assertion for SSA name NAME on edge E for
2528 the conditional jump pointed to by SI. Return true if an assertion
2529 for NAME could be registered. */
2532 register_edge_assert_for (tree name, edge e, block_stmt_iterator si)
2535 enum tree_code comp_code;
2537 stmt = bsi_stmt (si);
2539 /* Do not attempt to infer anything in names that flow through
2541 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
2544 /* If NAME was not found in the sub-graph reachable from E, then
2545 there's nothing to do. */
2546 if (!TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
2549 /* We found a use of NAME in the sub-graph rooted at E->DEST.
2550 Register an assertion for NAME according to the value that NAME
2552 if (TREE_CODE (stmt) == COND_EXPR)
2554 /* If BB ends in a COND_EXPR then NAME then we should insert
2555 the original predicate on EDGE_TRUE_VALUE and the
2556 opposite predicate on EDGE_FALSE_VALUE. */
2557 tree cond = COND_EXPR_COND (stmt);
2558 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
2560 /* Predicates may be a single SSA name or NAME OP VAL. */
2563 /* If the predicate is a name, it must be NAME, in which
2564 case we create the predicate NAME == true or
2565 NAME == false accordingly. */
2566 comp_code = EQ_EXPR;
2567 val = (is_else_edge) ? boolean_false_node : boolean_true_node;
2571 /* Otherwise, we have a comparison of the form NAME COMP VAL
2572 or VAL COMP NAME. */
2573 if (name == TREE_OPERAND (cond, 1))
2575 /* If the predicate is of the form VAL COMP NAME, flip
2576 COMP around because we need to register NAME as the
2577 first operand in the predicate. */
2578 comp_code = swap_tree_comparison (TREE_CODE (cond));
2579 val = TREE_OPERAND (cond, 0);
2583 /* The comparison is of the form NAME COMP VAL, so the
2584 comparison code remains unchanged. */
2585 comp_code = TREE_CODE (cond);
2586 val = TREE_OPERAND (cond, 1);
2589 /* If we are inserting the assertion on the ELSE edge, we
2590 need to invert the sign comparison. */
2592 comp_code = invert_tree_comparison (comp_code, 0);
2594 /* Do not register always-false predicates. FIXME, this
2595 works around a limitation in fold() when dealing with
2596 enumerations. Given 'enum { N1, N2 } x;', fold will not
2597 fold 'if (x > N2)' to 'if (0)'. */
2598 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
2599 && (INTEGRAL_TYPE_P (TREE_TYPE (val))
2600 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (val))))
2602 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
2603 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
2605 if (comp_code == GT_EXPR && compare_values (val, max) == 0)
2608 if (comp_code == LT_EXPR && compare_values (val, min) == 0)
2615 /* FIXME. Handle SWITCH_EXPR. */
2619 register_new_assert_for (name, comp_code, val, NULL, e, si);
2624 static bool find_assert_locations (basic_block bb);
2626 /* Determine whether the outgoing edges of BB should receive an
2627 ASSERT_EXPR for each of the operands of BB's last statement. The
2628 last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2630 If any of the sub-graphs rooted at BB have an interesting use of
2631 the predicate operands, an assert location node is added to the
2632 list of assertions for the corresponding operands. */
2635 find_conditional_asserts (basic_block bb)
2638 block_stmt_iterator last_si;
2644 need_assert = false;
2645 last_si = bsi_last (bb);
2646 last = bsi_stmt (last_si);
2648 /* Look for uses of the operands in each of the sub-graphs
2649 rooted at BB. We need to check each of the outgoing edges
2650 separately, so that we know what kind of ASSERT_EXPR to
2652 FOR_EACH_EDGE (e, ei, bb->succs)
2657 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
2658 Otherwise, when we finish traversing each of the sub-graphs, we
2659 won't know whether the variables were found in the sub-graphs or
2660 if they had been found in a block upstream from BB. */
2661 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2662 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2664 /* Traverse the strictly dominated sub-graph rooted at E->DEST
2665 to determine if any of the operands in the conditional
2666 predicate are used. */
2668 need_assert |= find_assert_locations (e->dest);
2670 /* Register the necessary assertions for each operand in the
2671 conditional predicate. */
2672 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2673 need_assert |= register_edge_assert_for (op, e, last_si);
2676 /* Finally, indicate that we have found the operands in the
2678 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2679 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2685 /* Traverse all the statements in block BB looking for statements that
2686 may generate useful assertions for the SSA names in their operand.
2687 If a statement produces a useful assertion A for name N_i, then the
2688 list of assertions already generated for N_i is scanned to
2689 determine if A is actually needed.
2691 If N_i already had the assertion A at a location dominating the
2692 current location, then nothing needs to be done. Otherwise, the
2693 new location for A is recorded instead.
2695 1- For every statement S in BB, all the variables used by S are
2696 added to bitmap FOUND_IN_SUBGRAPH.
2698 2- If statement S uses an operand N in a way that exposes a known
2699 value range for N, then if N was not already generated by an
2700 ASSERT_EXPR, create a new assert location for N. For instance,
2701 if N is a pointer and the statement dereferences it, we can
2702 assume that N is not NULL.
2704 3- COND_EXPRs are a special case of #2. We can derive range
2705 information from the predicate but need to insert different
2706 ASSERT_EXPRs for each of the sub-graphs rooted at the
2707 conditional block. If the last statement of BB is a conditional
2708 expression of the form 'X op Y', then
2710 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
2712 b) If the conditional is the only entry point to the sub-graph
2713 corresponding to the THEN_CLAUSE, recurse into it. On
2714 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
2715 an ASSERT_EXPR is added for the corresponding variable.
2717 c) Repeat step (b) on the ELSE_CLAUSE.
2719 d) Mark X and Y in FOUND_IN_SUBGRAPH.
2728 In this case, an assertion on the THEN clause is useful to
2729 determine that 'a' is always 9 on that edge. However, an assertion
2730 on the ELSE clause would be unnecessary.
2732 4- If BB does not end in a conditional expression, then we recurse
2733 into BB's dominator children.
2735 At the end of the recursive traversal, every SSA name will have a
2736 list of locations where ASSERT_EXPRs should be added. When a new
2737 location for name N is found, it is registered by calling
2738 register_new_assert_for. That function keeps track of all the
2739 registered assertions to prevent adding unnecessary assertions.
2740 For instance, if a pointer P_4 is dereferenced more than once in a
2741 dominator tree, only the location dominating all the dereference of
2742 P_4 will receive an ASSERT_EXPR.
2744 If this function returns true, then it means that there are names
2745 for which we need to generate ASSERT_EXPRs. Those assertions are
2746 inserted by process_assert_insertions.
2748 TODO. Handle SWITCH_EXPR. */
2751 find_assert_locations (basic_block bb)
2753 block_stmt_iterator si;
2758 if (TEST_BIT (blocks_visited, bb->index))
2761 SET_BIT (blocks_visited, bb->index);
2763 need_assert = false;
2765 /* Traverse all PHI nodes in BB marking used operands. */
2766 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
2768 use_operand_p arg_p;
2771 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
2773 tree arg = USE_FROM_PTR (arg_p);
2774 if (TREE_CODE (arg) == SSA_NAME)
2776 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
2777 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
2782 /* Traverse all the statements in BB marking used names and looking
2783 for statements that may infer assertions for their used operands. */
2785 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
2790 stmt = bsi_stmt (si);
2792 /* See if we can derive an assertion for any of STMT's operands. */
2793 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
2796 enum tree_code comp_code;
2798 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
2799 the sub-graph of a conditional block, when we return from
2800 this recursive walk, our parent will use the
2801 FOUND_IN_SUBGRAPH bitset to determine if one of the
2802 operands it was looking for was present in the sub-graph. */
2803 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2805 /* If OP is used only once, namely in this STMT, don't
2806 bother creating an ASSERT_EXPR for it. Such an
2807 ASSERT_EXPR would do nothing but increase compile time.
2808 Experiments show that with this simple check, we can save
2809 more than 20% of ASSERT_EXPRs. */
2810 if (has_single_use (op))
2813 /* If OP is used in such a way that we can infer a value
2814 range for it, and we don't find a previous assertion for
2815 it, create a new assertion location node for OP. */
2816 if (infer_value_range (stmt, op, &comp_code, &value))
2818 register_new_assert_for (op, comp_code, value, bb, NULL, si);
2823 /* Remember the last statement of the block. */
2827 /* If BB's last statement is a conditional expression
2828 involving integer operands, recurse into each of the sub-graphs
2829 rooted at BB to determine if we need to add ASSERT_EXPRs. */
2831 && TREE_CODE (last) == COND_EXPR
2832 && !fp_predicate (COND_EXPR_COND (last))
2833 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
2834 need_assert |= find_conditional_asserts (bb);
2836 /* Recurse into the dominator children of BB. */
2837 for (son = first_dom_son (CDI_DOMINATORS, bb);
2839 son = next_dom_son (CDI_DOMINATORS, son))
2840 need_assert |= find_assert_locations (son);
2846 /* Create an ASSERT_EXPR for NAME and insert it in the location
2847 indicated by LOC. Return true if we made any edge insertions. */
2850 process_assert_insertions_for (tree name, assert_locus_t loc)
2852 /* Build the comparison expression NAME_i COMP_CODE VAL. */
2853 tree stmt, cond, assert_expr;
2857 cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
2858 assert_expr = build_assert_expr_for (cond, name);
2862 /* We have been asked to insert the assertion on an edge. This
2863 is used only by COND_EXPR and SWITCH_EXPR assertions. */
2864 #if defined ENABLE_CHECKING
2865 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
2866 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
2869 bsi_insert_on_edge (loc->e, assert_expr);
2873 /* Otherwise, we can insert right after LOC->SI iff the
2874 statement must not be the last statement in the block. */
2875 stmt = bsi_stmt (loc->si);
2876 if (!stmt_ends_bb_p (stmt))
2878 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
2882 /* If STMT must be the last statement in BB, we can only insert new
2883 assertions on the non-abnormal edge out of BB. Note that since
2884 STMT is not control flow, there may only be one non-abnormal edge
2886 FOR_EACH_EDGE (e, ei, loc->bb->succs)
2887 if (!(e->flags & EDGE_ABNORMAL))
2889 bsi_insert_on_edge (e, assert_expr);
2897 /* Process all the insertions registered for every name N_i registered
2898 in NEED_ASSERT_FOR. The list of assertions to be inserted are
2899 found in ASSERTS_FOR[i]. */
2902 process_assert_insertions (void)
2906 bool update_edges_p = false;
2907 int num_asserts = 0;
2909 if (dump_file && (dump_flags & TDF_DETAILS))
2910 dump_all_asserts (dump_file);
2912 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2914 assert_locus_t loc = asserts_for[i];
2919 assert_locus_t next = loc->next;
2920 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
2928 bsi_commit_edge_inserts ();
2930 if (dump_file && (dump_flags & TDF_STATS))
2931 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
2936 /* Traverse the flowgraph looking for conditional jumps to insert range
2937 expressions. These range expressions are meant to provide information
2938 to optimizations that need to reason in terms of value ranges. They
2939 will not be expanded into RTL. For instance, given:
2948 this pass will transform the code into:
2954 x = ASSERT_EXPR <x, x < y>
2959 y = ASSERT_EXPR <y, x <= y>
2963 The idea is that once copy and constant propagation have run, other
2964 optimizations will be able to determine what ranges of values can 'x'
2965 take in different paths of the code, simply by checking the reaching
2966 definition of 'x'. */
2969 insert_range_assertions (void)
2975 found_in_subgraph = sbitmap_alloc (num_ssa_names);
2976 sbitmap_zero (found_in_subgraph);
2978 blocks_visited = sbitmap_alloc (last_basic_block);
2979 sbitmap_zero (blocks_visited);
2981 need_assert_for = BITMAP_ALLOC (NULL);
2982 asserts_for = xmalloc (num_ssa_names * sizeof (assert_locus_t));
2983 memset (asserts_for, 0, num_ssa_names * sizeof (assert_locus_t));
2985 calculate_dominance_info (CDI_DOMINATORS);
2987 update_ssa_p = false;
2988 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2989 if (find_assert_locations (e->dest))
2990 update_ssa_p = true;
2994 process_assert_insertions ();
2995 update_ssa (TODO_update_ssa_no_phi);
2998 if (dump_file && (dump_flags & TDF_DETAILS))
3000 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
3001 dump_function_to_file (current_function_decl, dump_file, dump_flags);
3004 sbitmap_free (found_in_subgraph);
3006 BITMAP_FREE (need_assert_for);
3010 /* Convert range assertion expressions into the implied copies and
3011 copy propagate away the copies. Doing the trivial copy propagation
3012 here avoids the need to run the full copy propagation pass after
3015 FIXME, this will eventually lead to copy propagation removing the
3016 names that had useful range information attached to them. For
3017 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
3018 then N_i will have the range [3, +INF].
3020 However, by converting the assertion into the implied copy
3021 operation N_i = N_j, we will then copy-propagate N_j into the uses
3022 of N_i and lose the range information. We may want to hold on to
3023 ASSERT_EXPRs a little while longer as the ranges could be used in
3024 things like jump threading.
3026 The problem with keeping ASSERT_EXPRs around is that passes after
3027 VRP need to handle them appropriately.
3029 Another approach would be to make the range information a first
3030 class property of the SSA_NAME so that it can be queried from
3031 any pass. This is made somewhat more complex by the need for
3032 multiple ranges to be associated with one SSA_NAME. */
3035 remove_range_assertions (void)
3038 block_stmt_iterator si;
3040 /* Note that the BSI iterator bump happens at the bottom of the
3041 loop and no bump is necessary if we're removing the statement
3042 referenced by the current BSI. */
3044 for (si = bsi_start (bb); !bsi_end_p (si);)
3046 tree stmt = bsi_stmt (si);
3048 if (TREE_CODE (stmt) == MODIFY_EXPR
3049 && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
3051 tree rhs = TREE_OPERAND (stmt, 1);
3052 tree cond = fold (ASSERT_EXPR_COND (rhs));
3053 use_operand_p use_p;
3054 imm_use_iterator iter;
3056 gcc_assert (cond != boolean_false_node);
3057 TREE_OPERAND (stmt, 1) = ASSERT_EXPR_VAR (rhs);
3060 /* The statement is now a copy. Propagate the RHS into
3061 every use of the LHS. */
3062 FOR_EACH_IMM_USE_SAFE (use_p, iter, TREE_OPERAND (stmt, 0))
3064 SET_USE (use_p, ASSERT_EXPR_VAR (rhs));
3065 update_stmt (USE_STMT (use_p));
3068 /* And finally, remove the copy, it is not needed. */
3069 bsi_remove (&si, true);
3075 sbitmap_free (blocks_visited);
3079 /* Return true if STMT is interesting for VRP. */
3082 stmt_interesting_for_vrp (tree stmt)
3084 if (TREE_CODE (stmt) == PHI_NODE
3085 && is_gimple_reg (PHI_RESULT (stmt))
3086 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
3087 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
3089 else if (TREE_CODE (stmt) == MODIFY_EXPR)
3091 tree lhs = TREE_OPERAND (stmt, 0);
3093 if (TREE_CODE (lhs) == SSA_NAME
3094 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3095 || POINTER_TYPE_P (TREE_TYPE (lhs)))
3096 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3099 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3106 /* Initialize local data structures for VRP. */
3109 vrp_initialize (void)
3113 vr_value = xmalloc (num_ssa_names * sizeof (value_range_t *));
3114 memset (vr_value, 0, num_ssa_names * sizeof (value_range_t *));
3118 block_stmt_iterator si;
3121 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3123 if (!stmt_interesting_for_vrp (phi))
3125 tree lhs = PHI_RESULT (phi);
3126 set_value_range_to_varying (get_value_range (lhs));
3127 DONT_SIMULATE_AGAIN (phi) = true;
3130 DONT_SIMULATE_AGAIN (phi) = false;
3133 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3135 tree stmt = bsi_stmt (si);
3137 if (!stmt_interesting_for_vrp (stmt))
3141 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
3142 set_value_range_to_varying (get_value_range (def));
3143 DONT_SIMULATE_AGAIN (stmt) = true;
3147 DONT_SIMULATE_AGAIN (stmt) = false;
3154 /* Visit assignment STMT. If it produces an interesting range, record
3155 the SSA name in *OUTPUT_P. */
3157 static enum ssa_prop_result
3158 vrp_visit_assignment (tree stmt, tree *output_p)
3163 lhs = TREE_OPERAND (stmt, 0);
3164 rhs = TREE_OPERAND (stmt, 1);
3166 /* We only keep track of ranges in integral and pointer types. */
3167 if (TREE_CODE (lhs) == SSA_NAME
3168 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3169 || POINTER_TYPE_P (TREE_TYPE (lhs))))
3172 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3174 extract_range_from_expr (&new_vr, rhs);
3176 /* If STMT is inside a loop, we may be able to know something
3177 else about the range of LHS by examining scalar evolution
3179 if (cfg_loops && (l = loop_containing_stmt (stmt)))
3180 adjust_range_with_scev (&new_vr, l, stmt, lhs);
3182 if (update_value_range (lhs, &new_vr))
3186 if (dump_file && (dump_flags & TDF_DETAILS))
3188 fprintf (dump_file, "Found new range for ");
3189 print_generic_expr (dump_file, lhs, 0);
3190 fprintf (dump_file, ": ");
3191 dump_value_range (dump_file, &new_vr);
3192 fprintf (dump_file, "\n\n");
3195 if (new_vr.type == VR_VARYING)
3196 return SSA_PROP_VARYING;
3198 return SSA_PROP_INTERESTING;
3201 return SSA_PROP_NOT_INTERESTING;
3204 /* Every other statement produces no useful ranges. */
3205 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3206 set_value_range_to_varying (get_value_range (def));
3208 return SSA_PROP_VARYING;
3212 /* Compare all the value ranges for names equivalent to VAR with VAL
3213 using comparison code COMP. Return the same value returned by
3214 compare_range_with_value. */
3217 compare_name_with_value (enum tree_code comp, tree var, tree val)
3224 t = retval = NULL_TREE;
3226 /* Get the set of equivalences for VAR. */
3227 e = get_value_range (var)->equiv;
3229 /* Add VAR to its own set of equivalences so that VAR's value range
3230 is processed by this loop (otherwise, we would have to replicate
3231 the body of the loop just to check VAR's value range). */
3232 bitmap_set_bit (e, SSA_NAME_VERSION (var));
3234 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
3236 value_range_t equiv_vr = *(vr_value[i]);
3238 /* If name N_i does not have a valid range, use N_i as its own
3239 range. This allows us to compare against names that may
3240 have N_i in their ranges. */
3241 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
3243 equiv_vr.type = VR_RANGE;
3244 equiv_vr.min = ssa_name (i);
3245 equiv_vr.max = ssa_name (i);
3248 t = compare_range_with_value (comp, &equiv_vr, val);
3251 /* All the ranges should compare the same against VAL. */
3252 gcc_assert (retval == NULL || t == retval);
3257 /* Remove VAR from its own equivalence set. */
3258 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
3263 /* We couldn't find a non-NULL value for the predicate. */
3268 /* Given a comparison code COMP and names N1 and N2, compare all the
3269 ranges equivalent to N1 against all the ranges equivalent to N2
3270 to determine the value of N1 COMP N2. Return the same value
3271 returned by compare_ranges. */
3274 compare_names (enum tree_code comp, tree n1, tree n2)
3278 bitmap_iterator bi1, bi2;
3281 /* Compare the ranges of every name equivalent to N1 against the
3282 ranges of every name equivalent to N2. */
3283 e1 = get_value_range (n1)->equiv;
3284 e2 = get_value_range (n2)->equiv;
3286 /* Add N1 and N2 to their own set of equivalences to avoid
3287 duplicating the body of the loop just to check N1 and N2
3289 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
3290 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
3292 /* If the equivalence sets have a common intersection, then the two
3293 names can be compared without checking their ranges. */
3294 if (bitmap_intersect_p (e1, e2))
3296 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3297 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3299 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
3301 : boolean_false_node;
3304 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3305 N2 to their own set of equivalences to avoid duplicating the body
3306 of the loop just to check N1 and N2 ranges. */
3307 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
3309 value_range_t vr1 = *(vr_value[i1]);
3311 /* If the range is VARYING or UNDEFINED, use the name itself. */
3312 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
3314 vr1.type = VR_RANGE;
3315 vr1.min = ssa_name (i1);
3316 vr1.max = ssa_name (i1);
3319 t = retval = NULL_TREE;
3320 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
3322 value_range_t vr2 = *(vr_value[i2]);
3324 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
3326 vr2.type = VR_RANGE;
3327 vr2.min = ssa_name (i2);
3328 vr2.max = ssa_name (i2);
3331 t = compare_ranges (comp, &vr1, &vr2);
3334 /* All the ranges in the equivalent sets should compare
3336 gcc_assert (retval == NULL || t == retval);
3343 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3344 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3349 /* None of the equivalent ranges are useful in computing this
3351 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3352 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3357 /* Given a conditional predicate COND, try to determine if COND yields
3358 true or false based on the value ranges of its operands. Return
3359 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3360 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3361 NULL if the conditional cannot be evaluated at compile time.
3363 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3364 the operands in COND are used when trying to compute its value.
3365 This is only used during final substitution. During propagation,
3366 we only check the range of each variable and not its equivalents. */
3369 vrp_evaluate_conditional (tree cond, bool use_equiv_p)
3371 gcc_assert (TREE_CODE (cond) == SSA_NAME
3372 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
3374 if (TREE_CODE (cond) == SSA_NAME)
3380 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node);
3383 value_range_t *vr = get_value_range (cond);
3384 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node);
3387 /* If COND has a known boolean range, return it. */
3391 /* Otherwise, if COND has a symbolic range of exactly one value,
3393 vr = get_value_range (cond);
3394 if (vr->type == VR_RANGE && vr->min == vr->max)
3399 tree op0 = TREE_OPERAND (cond, 0);
3400 tree op1 = TREE_OPERAND (cond, 1);
3402 /* We only deal with integral and pointer types. */
3403 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
3404 && !POINTER_TYPE_P (TREE_TYPE (op0)))
3409 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
3410 return compare_names (TREE_CODE (cond), op0, op1);
3411 else if (TREE_CODE (op0) == SSA_NAME)
3412 return compare_name_with_value (TREE_CODE (cond), op0, op1);
3413 else if (TREE_CODE (op1) == SSA_NAME)
3414 return compare_name_with_value (
3415 swap_tree_comparison (TREE_CODE (cond)), op1, op0);
3419 value_range_t *vr0, *vr1;
3421 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
3422 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
3425 return compare_ranges (TREE_CODE (cond), vr0, vr1);
3426 else if (vr0 && vr1 == NULL)
3427 return compare_range_with_value (TREE_CODE (cond), vr0, op1);
3428 else if (vr0 == NULL && vr1)
3429 return compare_range_with_value (
3430 swap_tree_comparison (TREE_CODE (cond)), vr1, op0);
3434 /* Anything else cannot be computed statically. */
3439 /* Visit conditional statement STMT. If we can determine which edge
3440 will be taken out of STMT's basic block, record it in
3441 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3442 SSA_PROP_VARYING. */
3444 static enum ssa_prop_result
3445 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
3449 *taken_edge_p = NULL;
3451 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3452 add ASSERT_EXPRs for them. */
3453 if (TREE_CODE (stmt) == SWITCH_EXPR)
3454 return SSA_PROP_VARYING;
3456 cond = COND_EXPR_COND (stmt);
3458 if (dump_file && (dump_flags & TDF_DETAILS))
3463 fprintf (dump_file, "\nVisiting conditional with predicate: ");
3464 print_generic_expr (dump_file, cond, 0);
3465 fprintf (dump_file, "\nWith known ranges\n");
3467 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
3469 fprintf (dump_file, "\t");
3470 print_generic_expr (dump_file, use, 0);
3471 fprintf (dump_file, ": ");
3472 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
3475 fprintf (dump_file, "\n");
3478 /* Compute the value of the predicate COND by checking the known
3479 ranges of each of its operands.
3481 Note that we cannot evaluate all the equivalent ranges here
3482 because those ranges may not yet be final and with the current
3483 propagation strategy, we cannot determine when the value ranges
3484 of the names in the equivalence set have changed.
3486 For instance, given the following code fragment
3490 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3494 Assume that on the first visit to i_14, i_5 has the temporary
3495 range [8, 8] because the second argument to the PHI function is
3496 not yet executable. We derive the range ~[0, 0] for i_14 and the
3497 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3498 the first time, since i_14 is equivalent to the range [8, 8], we
3499 determine that the predicate is always false.
3501 On the next round of propagation, i_13 is determined to be
3502 VARYING, which causes i_5 to drop down to VARYING. So, another
3503 visit to i_14 is scheduled. In this second visit, we compute the
3504 exact same range and equivalence set for i_14, namely ~[0, 0] and
3505 { i_5 }. But we did not have the previous range for i_5
3506 registered, so vrp_visit_assignment thinks that the range for
3507 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3508 is not visited again, which stops propagation from visiting
3509 statements in the THEN clause of that if().
3511 To properly fix this we would need to keep the previous range
3512 value for the names in the equivalence set. This way we would've
3513 discovered that from one visit to the other i_5 changed from
3514 range [8, 8] to VR_VARYING.
3516 However, fixing this apparent limitation may not be worth the
3517 additional checking. Testing on several code bases (GCC, DLV,
3518 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3519 4 more predicates folded in SPEC. */
3520 val = vrp_evaluate_conditional (cond, false);
3522 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
3524 if (dump_file && (dump_flags & TDF_DETAILS))
3526 fprintf (dump_file, "\nPredicate evaluates to: ");
3527 if (val == NULL_TREE)
3528 fprintf (dump_file, "DON'T KNOW\n");
3530 print_generic_stmt (dump_file, val, 0);
3533 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
3537 /* Evaluate statement STMT. If the statement produces a useful range,
3538 return SSA_PROP_INTERESTING and record the SSA name with the
3539 interesting range into *OUTPUT_P.
3541 If STMT is a conditional branch and we can determine its truth
3542 value, the taken edge is recorded in *TAKEN_EDGE_P.
3544 If STMT produces a varying value, return SSA_PROP_VARYING. */
3546 static enum ssa_prop_result
3547 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
3553 if (dump_file && (dump_flags & TDF_DETAILS))
3555 fprintf (dump_file, "\nVisiting statement:\n");
3556 print_generic_stmt (dump_file, stmt, dump_flags);
3557 fprintf (dump_file, "\n");
3560 ann = stmt_ann (stmt);
3561 if (TREE_CODE (stmt) == MODIFY_EXPR
3562 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3563 return vrp_visit_assignment (stmt, output_p);
3564 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3565 return vrp_visit_cond_stmt (stmt, taken_edge_p);
3567 /* All other statements produce nothing of interest for VRP, so mark
3568 their outputs varying and prevent further simulation. */
3569 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3570 set_value_range_to_varying (get_value_range (def));
3572 return SSA_PROP_VARYING;
3576 /* Meet operation for value ranges. Given two value ranges VR0 and
3577 VR1, store in VR0 the result of meeting VR0 and VR1.
3579 The meeting rules are as follows:
3581 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
3583 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
3584 union of VR0 and VR1. */
3587 vrp_meet (value_range_t *vr0, value_range_t *vr1)
3589 if (vr0->type == VR_UNDEFINED)
3591 copy_value_range (vr0, vr1);
3595 if (vr1->type == VR_UNDEFINED)
3597 /* Nothing to do. VR0 already has the resulting range. */
3601 if (vr0->type == VR_VARYING)
3603 /* Nothing to do. VR0 already has the resulting range. */
3607 if (vr1->type == VR_VARYING)
3609 set_value_range_to_varying (vr0);
3613 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
3615 /* If VR0 and VR1 have a non-empty intersection, compute the
3616 union of both ranges. */
3617 if (value_ranges_intersect_p (vr0, vr1))
3622 /* The lower limit of the new range is the minimum of the
3623 two ranges. If they cannot be compared, the result is
3625 cmp = compare_values (vr0->min, vr1->min);
3626 if (cmp == 0 || cmp == 1)
3632 set_value_range_to_varying (vr0);
3636 /* Similarly, the upper limit of the new range is the
3637 maximum of the two ranges. If they cannot be compared,
3638 the result is VARYING. */
3639 cmp = compare_values (vr0->max, vr1->max);
3640 if (cmp == 0 || cmp == -1)
3646 set_value_range_to_varying (vr0);
3650 /* The resulting set of equivalences is the intersection of
3652 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3653 bitmap_and_into (vr0->equiv, vr1->equiv);
3654 else if (vr0->equiv && !vr1->equiv)
3655 bitmap_clear (vr0->equiv);
3657 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
3662 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
3664 /* Two anti-ranges meet only if they are both identical. */
3665 if (compare_values (vr0->min, vr1->min) == 0
3666 && compare_values (vr0->max, vr1->max) == 0
3667 && compare_values (vr0->min, vr0->max) == 0)
3669 /* The resulting set of equivalences is the intersection of
3671 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3672 bitmap_and_into (vr0->equiv, vr1->equiv);
3673 else if (vr0->equiv && !vr1->equiv)
3674 bitmap_clear (vr0->equiv);
3679 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
3681 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
3682 meet only if the ranges have an empty intersection. The
3683 result of the meet operation is the anti-range. */
3684 if (!symbolic_range_p (vr0)
3685 && !symbolic_range_p (vr1)
3686 && !value_ranges_intersect_p (vr0, vr1))
3688 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
3689 set. We need to compute the intersection of the two
3690 equivalence sets. */
3691 if (vr1->type == VR_ANTI_RANGE)
3692 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
3694 /* The resulting set of equivalences is the intersection of
3696 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3697 bitmap_and_into (vr0->equiv, vr1->equiv);
3698 else if (vr0->equiv && !vr1->equiv)
3699 bitmap_clear (vr0->equiv);
3710 /* The two range VR0 and VR1 do not meet. Before giving up and
3711 setting the result to VARYING, see if we can at least derive a
3712 useful anti-range. FIXME, all this nonsense about distinguishing
3713 anti-ranges from ranges is necessary because of the odd
3714 semantics of range_includes_zero_p and friends. */
3715 if (!symbolic_range_p (vr0)
3716 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
3717 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
3718 && !symbolic_range_p (vr1)
3719 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
3720 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
3722 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
3724 /* Since this meet operation did not result from the meeting of
3725 two equivalent names, VR0 cannot have any equivalences. */
3727 bitmap_clear (vr0->equiv);
3730 set_value_range_to_varying (vr0);
3734 /* Visit all arguments for PHI node PHI that flow through executable
3735 edges. If a valid value range can be derived from all the incoming
3736 value ranges, set a new range for the LHS of PHI. */
3738 static enum ssa_prop_result
3739 vrp_visit_phi_node (tree phi)
3742 tree lhs = PHI_RESULT (phi);
3743 value_range_t *lhs_vr = get_value_range (lhs);
3744 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3746 copy_value_range (&vr_result, lhs_vr);
3748 if (dump_file && (dump_flags & TDF_DETAILS))
3750 fprintf (dump_file, "\nVisiting PHI node: ");
3751 print_generic_expr (dump_file, phi, dump_flags);
3754 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
3756 edge e = PHI_ARG_EDGE (phi, i);
3758 if (dump_file && (dump_flags & TDF_DETAILS))
3761 "\n Argument #%d (%d -> %d %sexecutable)\n",
3762 i, e->src->index, e->dest->index,
3763 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
3766 if (e->flags & EDGE_EXECUTABLE)
3768 tree arg = PHI_ARG_DEF (phi, i);
3769 value_range_t vr_arg;
3771 if (TREE_CODE (arg) == SSA_NAME)
3772 vr_arg = *(get_value_range (arg));
3775 vr_arg.type = VR_RANGE;
3778 vr_arg.equiv = NULL;
3781 if (dump_file && (dump_flags & TDF_DETAILS))
3783 fprintf (dump_file, "\t");
3784 print_generic_expr (dump_file, arg, dump_flags);
3785 fprintf (dump_file, "\n\tValue: ");
3786 dump_value_range (dump_file, &vr_arg);
3787 fprintf (dump_file, "\n");
3790 vrp_meet (&vr_result, &vr_arg);
3792 if (vr_result.type == VR_VARYING)
3797 if (vr_result.type == VR_VARYING)
3800 /* To prevent infinite iterations in the algorithm, derive ranges
3801 when the new value is slightly bigger or smaller than the
3803 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE)
3805 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
3807 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
3808 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
3810 /* If the new minimum is smaller or larger than the previous
3811 one, go all the way to -INF. In the first case, to avoid
3812 iterating millions of times to reach -INF, and in the
3813 other case to avoid infinite bouncing between different
3815 if (cmp_min > 0 || cmp_min < 0)
3816 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
3818 /* Similarly, if the new maximum is smaller or larger than
3819 the previous one, go all the way to +INF. */
3820 if (cmp_max < 0 || cmp_max > 0)
3821 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
3823 /* If we ended up with a (-INF, +INF) range, set it to
3825 if (vr_result.min == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))
3826 && vr_result.max == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)))
3831 /* If the new range is different than the previous value, keep
3833 if (update_value_range (lhs, &vr_result))
3834 return SSA_PROP_INTERESTING;
3836 /* Nothing changed, don't add outgoing edges. */
3837 return SSA_PROP_NOT_INTERESTING;
3839 /* No match found. Set the LHS to VARYING. */
3841 set_value_range_to_varying (lhs_vr);
3842 return SSA_PROP_VARYING;
3845 /* Simplify a division or modulo operator to a right shift or
3846 bitwise and if the first operand is unsigned or is greater
3847 than zero and the second operand is an exact power of two. */
3850 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
3853 tree op = TREE_OPERAND (rhs, 0);
3854 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
3856 if (TYPE_UNSIGNED (TREE_TYPE (op)))
3858 val = integer_one_node;
3862 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node);
3865 if (val && integer_onep (val))
3868 tree op0 = TREE_OPERAND (rhs, 0);
3869 tree op1 = TREE_OPERAND (rhs, 1);
3871 if (rhs_code == TRUNC_DIV_EXPR)
3873 t = build_int_cst (NULL_TREE, tree_log2 (op1));
3874 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
3878 t = build_int_cst (TREE_TYPE (op1), 1);
3879 t = int_const_binop (MINUS_EXPR, op1, t, 0);
3880 t = fold_convert (TREE_TYPE (op0), t);
3881 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
3884 TREE_OPERAND (stmt, 1) = t;
3889 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
3890 ABS_EXPR. If the operand is <= 0, then simplify the
3891 ABS_EXPR into a NEGATE_EXPR. */
3894 simplify_abs_using_ranges (tree stmt, tree rhs)
3897 tree op = TREE_OPERAND (rhs, 0);
3898 tree type = TREE_TYPE (op);
3899 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
3901 if (TYPE_UNSIGNED (type))
3903 val = integer_zero_node;
3907 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node);
3910 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node);
3914 if (integer_zerop (val))
3915 val = integer_one_node;
3916 else if (integer_onep (val))
3917 val = integer_zero_node;
3922 && (integer_onep (val) || integer_zerop (val)))
3926 if (integer_onep (val))
3927 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
3931 TREE_OPERAND (stmt, 1) = t;
3937 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
3938 a known value range VR.
3940 If there is one and only one value which will satisfy the
3941 conditional, then return that value. Else return NULL. */
3944 test_for_singularity (enum tree_code cond_code, tree op0,
3945 tree op1, value_range_t *vr)
3950 /* Extract minimum/maximum values which satisfy the
3951 the conditional as it was written. */
3952 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
3954 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
3957 if (cond_code == LT_EXPR)
3959 tree one = build_int_cst (TREE_TYPE (op0), 1);
3960 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
3963 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
3965 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
3968 if (cond_code == GT_EXPR)
3970 tree one = build_int_cst (TREE_TYPE (op0), 1);
3971 max = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), max, one);
3975 /* Now refine the minimum and maximum values using any
3976 value range information we have for op0. */
3979 if (compare_values (vr->min, min) == -1)
3983 if (compare_values (vr->max, max) == 1)
3988 /* If the new min/max values have converged to a
3989 single value, then there is only one value which
3990 can satisfy the condition, return that value. */
3991 if (min == max && is_gimple_min_invariant (min))
3997 /* Simplify a conditional using a relational operator to an equality
3998 test if the range information indicates only one value can satisfy
3999 the original conditional. */
4002 simplify_cond_using_ranges (tree stmt)
4004 tree cond = COND_EXPR_COND (stmt);
4005 tree op0 = TREE_OPERAND (cond, 0);
4006 tree op1 = TREE_OPERAND (cond, 1);
4007 enum tree_code cond_code = TREE_CODE (cond);
4009 if (cond_code != NE_EXPR
4010 && cond_code != EQ_EXPR
4011 && TREE_CODE (op0) == SSA_NAME
4012 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
4013 && is_gimple_min_invariant (op1))
4015 value_range_t *vr = get_value_range (op0);
4017 /* If we have range information for OP0, then we might be
4018 able to simplify this conditional. */
4019 if (vr->type == VR_RANGE)
4021 tree new = test_for_singularity (cond_code, op0, op1, vr);
4027 fprintf (dump_file, "Simplified relational ");
4028 print_generic_expr (dump_file, cond, 0);
4029 fprintf (dump_file, " into ");
4032 COND_EXPR_COND (stmt)
4033 = build2 (EQ_EXPR, boolean_type_node, op0, new);
4038 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4039 fprintf (dump_file, "\n");
4045 /* Try again after inverting the condition. We only deal
4046 with integral types here, so no need to worry about
4047 issues with inverting FP comparisons. */
4048 cond_code = invert_tree_comparison (cond_code, false);
4049 new = test_for_singularity (cond_code, op0, op1, vr);
4055 fprintf (dump_file, "Simplified relational ");
4056 print_generic_expr (dump_file, cond, 0);
4057 fprintf (dump_file, " into ");
4060 COND_EXPR_COND (stmt)
4061 = build2 (NE_EXPR, boolean_type_node, op0, new);
4066 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4067 fprintf (dump_file, "\n");
4076 /* Simplify STMT using ranges if possible. */
4079 simplify_stmt_using_ranges (tree stmt)
4081 if (TREE_CODE (stmt) == MODIFY_EXPR)
4083 tree rhs = TREE_OPERAND (stmt, 1);
4084 enum tree_code rhs_code = TREE_CODE (rhs);
4086 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
4087 and BIT_AND_EXPR respectively if the first operand is greater
4088 than zero and the second operand is an exact power of two. */
4089 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
4090 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
4091 && integer_pow2p (TREE_OPERAND (rhs, 1)))
4092 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
4094 /* Transform ABS (X) into X or -X as appropriate. */
4095 if (rhs_code == ABS_EXPR
4096 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
4097 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
4098 simplify_abs_using_ranges (stmt, rhs);
4100 else if (TREE_CODE (stmt) == COND_EXPR
4101 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
4103 simplify_cond_using_ranges (stmt);
4109 /* Traverse all the blocks folding conditionals with known ranges. */
4115 prop_value_t *single_val_range;
4116 bool do_value_subst_p;
4120 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
4121 dump_all_value_ranges (dump_file);
4122 fprintf (dump_file, "\n");
4125 /* We may have ended with ranges that have exactly one value. Those
4126 values can be substituted as any other copy/const propagated
4127 value using substitute_and_fold. */
4128 single_val_range = xmalloc (num_ssa_names * sizeof (*single_val_range));
4129 memset (single_val_range, 0, num_ssa_names * sizeof (*single_val_range));
4131 do_value_subst_p = false;
4132 for (i = 0; i < num_ssa_names; i++)
4134 && vr_value[i]->type == VR_RANGE
4135 && vr_value[i]->min == vr_value[i]->max)
4137 single_val_range[i].value = vr_value[i]->min;
4138 do_value_subst_p = true;
4141 if (!do_value_subst_p)
4143 /* We found no single-valued ranges, don't waste time trying to
4144 do single value substitution in substitute_and_fold. */
4145 free (single_val_range);
4146 single_val_range = NULL;
4149 substitute_and_fold (single_val_range, true);
4151 /* Free allocated memory. */
4152 for (i = 0; i < num_ssa_names; i++)
4155 BITMAP_FREE (vr_value[i]->equiv);
4159 free (single_val_range);
4164 /* Main entry point to VRP (Value Range Propagation). This pass is
4165 loosely based on J. R. C. Patterson, ``Accurate Static Branch
4166 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
4167 Programming Language Design and Implementation, pp. 67-78, 1995.
4168 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
4170 This is essentially an SSA-CCP pass modified to deal with ranges
4171 instead of constants.
4173 While propagating ranges, we may find that two or more SSA name
4174 have equivalent, though distinct ranges. For instance,
4177 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
4179 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
4183 In the code above, pointer p_5 has range [q_2, q_2], but from the
4184 code we can also determine that p_5 cannot be NULL and, if q_2 had
4185 a non-varying range, p_5's range should also be compatible with it.
4187 These equivalences are created by two expressions: ASSERT_EXPR and
4188 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
4189 result of another assertion, then we can use the fact that p_5 and
4190 p_4 are equivalent when evaluating p_5's range.
4192 Together with value ranges, we also propagate these equivalences
4193 between names so that we can take advantage of information from
4194 multiple ranges when doing final replacement. Note that this
4195 equivalency relation is transitive but not symmetric.
4197 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
4198 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
4199 in contexts where that assertion does not hold (e.g., in line 6).
4201 TODO, the main difference between this pass and Patterson's is that
4202 we do not propagate edge probabilities. We only compute whether
4203 edges can be taken or not. That is, instead of having a spectrum
4204 of jump probabilities between 0 and 1, we only deal with 0, 1 and
4205 DON'T KNOW. In the future, it may be worthwhile to propagate
4206 probabilities to aid branch prediction. */
4211 insert_range_assertions ();
4213 cfg_loops = loop_optimizer_init (NULL);
4215 scev_initialize (cfg_loops);
4218 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
4224 loop_optimizer_finalize (cfg_loops, NULL);
4225 current_loops = NULL;
4228 remove_range_assertions ();
4234 return flag_tree_vrp != 0;
4237 struct tree_opt_pass pass_vrp =
4240 gate_vrp, /* gate */
4241 execute_vrp, /* execute */
4244 0, /* static_pass_number */
4245 TV_TREE_VRP, /* tv_id */
4246 PROP_ssa | PROP_alias, /* properties_required */
4247 0, /* properties_provided */
4248 0, /* properties_destroyed */
4249 0, /* todo_flags_start */
4254 | TODO_update_ssa, /* todo_flags_finish */