1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005, 2006 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
24 #include "coretypes.h"
29 #include "basic-block.h"
30 #include "tree-flow.h"
31 #include "tree-pass.h"
32 #include "tree-dump.h"
34 #include "diagnostic.h"
36 #include "tree-scalar-evolution.h"
37 #include "tree-ssa-propagate.h"
38 #include "tree-chrec.h"
40 /* Set of SSA names found during the dominator traversal of a
41 sub-graph in find_assert_locations. */
42 static sbitmap found_in_subgraph;
44 /* 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 (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
1416 || !is_gimple_min_invariant (max) || TREE_OVERFLOW (max))
1421 if (!is_gimple_min_invariant (val[i]) || TREE_OVERFLOW (val[i]))
1423 /* If we found an overflowed value, set MIN and MAX
1424 to it so that we set the resulting range to
1430 if (compare_values (val[i], min) == -1)
1433 if (compare_values (val[i], max) == 1)
1438 else if (code == MINUS_EXPR)
1440 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1441 VR_VARYING. It would take more effort to compute a precise
1442 range for such a case. For example, if we have op0 == 1 and
1443 op1 == 1 with their ranges both being ~[0,0], we would have
1444 op0 - op1 == 0, so we cannot claim that the difference is in
1445 ~[0,0]. Note that we are guaranteed to have
1446 vr0.type == vr1.type at this point. */
1447 if (vr0.type == VR_ANTI_RANGE)
1449 set_value_range_to_varying (vr);
1453 /* For MINUS_EXPR, apply the operation to the opposite ends of
1455 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1456 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1458 else if (code == BIT_AND_EXPR)
1460 if (vr0.type == VR_RANGE
1461 && vr0.min == vr0.max
1462 && tree_expr_nonnegative_p (vr0.max)
1463 && TREE_CODE (vr0.max) == INTEGER_CST)
1465 min = build_int_cst (TREE_TYPE (expr), 0);
1468 else if (vr1.type == VR_RANGE
1469 && vr1.min == vr1.max
1470 && tree_expr_nonnegative_p (vr1.max)
1471 && TREE_CODE (vr1.max) == INTEGER_CST)
1474 min = build_int_cst (TREE_TYPE (expr), 0);
1479 set_value_range_to_varying (vr);
1486 /* If either MIN or MAX overflowed, then set the resulting range to
1488 if (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
1489 || !is_gimple_min_invariant (max) || TREE_OVERFLOW (max))
1491 set_value_range_to_varying (vr);
1495 cmp = compare_values (min, max);
1496 if (cmp == -2 || cmp == 1)
1498 /* If the new range has its limits swapped around (MIN > MAX),
1499 then the operation caused one of them to wrap around, mark
1500 the new range VARYING. */
1501 set_value_range_to_varying (vr);
1504 set_value_range (vr, type, min, max, NULL);
1508 /* Extract range information from a unary expression EXPR based on
1509 the range of its operand and the expression code. */
1512 extract_range_from_unary_expr (value_range_t *vr, tree expr)
1514 enum tree_code code = TREE_CODE (expr);
1517 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1519 /* Refuse to operate on certain unary expressions for which we
1520 cannot easily determine a resulting range. */
1521 if (code == FIX_TRUNC_EXPR
1522 || code == FIX_CEIL_EXPR
1523 || code == FIX_FLOOR_EXPR
1524 || code == FIX_ROUND_EXPR
1525 || code == FLOAT_EXPR
1526 || code == BIT_NOT_EXPR
1527 || code == NON_LVALUE_EXPR
1528 || code == CONJ_EXPR)
1530 set_value_range_to_varying (vr);
1534 /* Get value ranges for the operand. For constant operands, create
1535 a new value range with the operand to simplify processing. */
1536 op0 = TREE_OPERAND (expr, 0);
1537 if (TREE_CODE (op0) == SSA_NAME)
1538 vr0 = *(get_value_range (op0));
1539 else if (is_gimple_min_invariant (op0))
1540 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1542 set_value_range_to_varying (&vr0);
1544 /* If VR0 is UNDEFINED, so is the result. */
1545 if (vr0.type == VR_UNDEFINED)
1547 set_value_range_to_undefined (vr);
1551 /* Refuse to operate on varying and symbolic ranges. Also, if the
1552 operand is neither a pointer nor an integral type, set the
1553 resulting range to VARYING. TODO, in some cases we may be able
1554 to derive anti-ranges (like nonzero values). */
1555 if (vr0.type == VR_VARYING
1556 || (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
1557 && !POINTER_TYPE_P (TREE_TYPE (op0)))
1558 || symbolic_range_p (&vr0))
1560 set_value_range_to_varying (vr);
1564 /* If the expression involves pointers, we are only interested in
1565 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1566 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
1568 if (range_is_nonnull (&vr0) || tree_expr_nonzero_p (expr))
1569 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1570 else if (range_is_null (&vr0))
1571 set_value_range_to_null (vr, TREE_TYPE (expr));
1573 set_value_range_to_varying (vr);
1578 /* Handle unary expressions on integer ranges. */
1579 if (code == NOP_EXPR || code == CONVERT_EXPR)
1581 tree inner_type = TREE_TYPE (op0);
1582 tree outer_type = TREE_TYPE (expr);
1584 /* If VR0 represents a simple range, then try to convert
1585 the min and max values for the range to the same type
1586 as OUTER_TYPE. If the results compare equal to VR0's
1587 min and max values and the new min is still less than
1588 or equal to the new max, then we can safely use the newly
1589 computed range for EXPR. This allows us to compute
1590 accurate ranges through many casts. */
1591 if (vr0.type == VR_RANGE)
1593 tree new_min, new_max;
1595 /* Convert VR0's min/max to OUTER_TYPE. */
1596 new_min = fold_convert (outer_type, vr0.min);
1597 new_max = fold_convert (outer_type, vr0.max);
1599 /* Verify the new min/max values are gimple values and
1600 that they compare equal to VR0's min/max values. */
1601 if (is_gimple_val (new_min)
1602 && is_gimple_val (new_max)
1603 && tree_int_cst_equal (new_min, vr0.min)
1604 && tree_int_cst_equal (new_max, vr0.max)
1605 && compare_values (new_min, new_max) <= 0
1606 && compare_values (new_min, new_max) >= -1)
1608 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
1613 /* When converting types of different sizes, set the result to
1614 VARYING. Things like sign extensions and precision loss may
1615 change the range. For instance, if x_3 is of type 'long long
1616 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1617 is impossible to know at compile time whether y_5 will be
1619 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
1620 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
1622 set_value_range_to_varying (vr);
1627 /* Apply the operation to each end of the range and see what we end
1629 if (code == NEGATE_EXPR
1630 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1632 /* NEGATE_EXPR flips the range around. */
1633 min = (vr0.max == TYPE_MAX_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
1634 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1635 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1637 max = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
1638 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1639 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1641 else if (code == ABS_EXPR
1642 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1644 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1647 && ((vr0.type == VR_RANGE
1648 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1649 || (vr0.type == VR_ANTI_RANGE
1650 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
1651 && !range_includes_zero_p (&vr0))))
1653 set_value_range_to_varying (vr);
1657 /* ABS_EXPR may flip the range around, if the original range
1658 included negative values. */
1659 min = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1660 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1661 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1663 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1665 cmp = compare_values (min, max);
1667 /* If a VR_ANTI_RANGEs contains zero, then we have
1668 ~[-INF, min(MIN, MAX)]. */
1669 if (vr0.type == VR_ANTI_RANGE)
1671 if (range_includes_zero_p (&vr0))
1673 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
1675 /* Take the lower of the two values. */
1679 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1680 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1681 flag_wrapv is set and the original anti-range doesn't include
1682 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1683 min = (flag_wrapv && vr0.min != type_min_value
1684 ? int_const_binop (PLUS_EXPR,
1686 integer_one_node, 0)
1691 /* All else has failed, so create the range [0, INF], even for
1692 flag_wrapv since TYPE_MIN_VALUE is in the original
1694 vr0.type = VR_RANGE;
1695 min = build_int_cst (TREE_TYPE (expr), 0);
1696 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
1700 /* If the range contains zero then we know that the minimum value in the
1701 range will be zero. */
1702 else if (range_includes_zero_p (&vr0))
1706 min = build_int_cst (TREE_TYPE (expr), 0);
1710 /* If the range was reversed, swap MIN and MAX. */
1721 /* Otherwise, operate on each end of the range. */
1722 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1723 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1726 cmp = compare_values (min, max);
1727 if (cmp == -2 || cmp == 1)
1729 /* If the new range has its limits swapped around (MIN > MAX),
1730 then the operation caused one of them to wrap around, mark
1731 the new range VARYING. */
1732 set_value_range_to_varying (vr);
1735 set_value_range (vr, vr0.type, min, max, NULL);
1739 /* Extract range information from a comparison expression EXPR based
1740 on the range of its operand and the expression code. */
1743 extract_range_from_comparison (value_range_t *vr, tree expr)
1745 tree val = vrp_evaluate_conditional (expr, false);
1748 /* Since this expression was found on the RHS of an assignment,
1749 its type may be different from _Bool. Convert VAL to EXPR's
1751 val = fold_convert (TREE_TYPE (expr), val);
1752 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
1755 set_value_range_to_varying (vr);
1759 /* Try to compute a useful range out of expression EXPR and store it
1763 extract_range_from_expr (value_range_t *vr, tree expr)
1765 enum tree_code code = TREE_CODE (expr);
1767 if (code == ASSERT_EXPR)
1768 extract_range_from_assert (vr, expr);
1769 else if (code == SSA_NAME)
1770 extract_range_from_ssa_name (vr, expr);
1771 else if (TREE_CODE_CLASS (code) == tcc_binary
1772 || code == TRUTH_ANDIF_EXPR
1773 || code == TRUTH_ORIF_EXPR
1774 || code == TRUTH_AND_EXPR
1775 || code == TRUTH_OR_EXPR
1776 || code == TRUTH_XOR_EXPR)
1777 extract_range_from_binary_expr (vr, expr);
1778 else if (TREE_CODE_CLASS (code) == tcc_unary)
1779 extract_range_from_unary_expr (vr, expr);
1780 else if (TREE_CODE_CLASS (code) == tcc_comparison)
1781 extract_range_from_comparison (vr, expr);
1782 else if (is_gimple_min_invariant (expr))
1783 set_value_range (vr, VR_RANGE, expr, expr, NULL);
1784 else if (vrp_expr_computes_nonzero (expr))
1785 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1787 set_value_range_to_varying (vr);
1790 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1791 would be profitable to adjust VR using scalar evolution information
1792 for VAR. If so, update VR with the new limits. */
1795 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
1798 tree init, step, chrec;
1799 bool init_is_max, unknown_max;
1801 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1802 better opportunities than a regular range, but I'm not sure. */
1803 if (vr->type == VR_ANTI_RANGE)
1806 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
1807 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
1810 init = initial_condition_in_loop_num (chrec, loop->num);
1811 step = evolution_part_in_loop_num (chrec, loop->num);
1813 /* If STEP is symbolic, we can't know whether INIT will be the
1814 minimum or maximum value in the range. */
1815 if (step == NULL_TREE
1816 || !is_gimple_min_invariant (step))
1819 /* Do not adjust ranges when chrec may wrap. */
1820 if (scev_probably_wraps_p (chrec_type (chrec), init, step, stmt,
1821 cfg_loops->parray[CHREC_VARIABLE (chrec)],
1822 &init_is_max, &unknown_max)
1826 if (!POINTER_TYPE_P (TREE_TYPE (init))
1827 && (vr->type == VR_VARYING || vr->type == VR_UNDEFINED))
1829 /* For VARYING or UNDEFINED ranges, just about anything we get
1830 from scalar evolutions should be better. */
1832 set_value_range (vr, VR_RANGE, TYPE_MIN_VALUE (TREE_TYPE (init)),
1835 set_value_range (vr, VR_RANGE, init, TYPE_MAX_VALUE (TREE_TYPE (init)),
1838 else if (vr->type == VR_RANGE)
1845 /* INIT is the maximum value. If INIT is lower than VR->MAX
1846 but no smaller than VR->MIN, set VR->MAX to INIT. */
1847 if (compare_values (init, max) == -1)
1851 /* If we just created an invalid range with the minimum
1852 greater than the maximum, take the minimum all the
1854 if (compare_values (min, max) == 1)
1855 min = TYPE_MIN_VALUE (TREE_TYPE (min));
1860 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
1861 if (compare_values (init, min) == 1)
1865 /* If we just created an invalid range with the minimum
1866 greater than the maximum, take the maximum all the
1868 if (compare_values (min, max) == 1)
1869 max = TYPE_MAX_VALUE (TREE_TYPE (max));
1873 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
1878 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
1880 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
1881 all the values in the ranges.
1883 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
1885 - Return NULL_TREE if it is not always possible to determine the
1886 value of the comparison. */
1890 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1)
1892 /* VARYING or UNDEFINED ranges cannot be compared. */
1893 if (vr0->type == VR_VARYING
1894 || vr0->type == VR_UNDEFINED
1895 || vr1->type == VR_VARYING
1896 || vr1->type == VR_UNDEFINED)
1899 /* Anti-ranges need to be handled separately. */
1900 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
1902 /* If both are anti-ranges, then we cannot compute any
1904 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
1907 /* These comparisons are never statically computable. */
1914 /* Equality can be computed only between a range and an
1915 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
1916 if (vr0->type == VR_RANGE)
1918 /* To simplify processing, make VR0 the anti-range. */
1919 value_range_t *tmp = vr0;
1924 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
1926 if (compare_values (vr0->min, vr1->min) == 0
1927 && compare_values (vr0->max, vr1->max) == 0)
1928 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
1933 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
1934 operands around and change the comparison code. */
1935 if (comp == GT_EXPR || comp == GE_EXPR)
1938 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
1944 if (comp == EQ_EXPR)
1946 /* Equality may only be computed if both ranges represent
1947 exactly one value. */
1948 if (compare_values (vr0->min, vr0->max) == 0
1949 && compare_values (vr1->min, vr1->max) == 0)
1951 int cmp_min = compare_values (vr0->min, vr1->min);
1952 int cmp_max = compare_values (vr0->max, vr1->max);
1953 if (cmp_min == 0 && cmp_max == 0)
1954 return boolean_true_node;
1955 else if (cmp_min != -2 && cmp_max != -2)
1956 return boolean_false_node;
1958 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
1959 else if (compare_values (vr0->min, vr1->max) == 1
1960 || compare_values (vr1->min, vr0->max) == 1)
1961 return boolean_false_node;
1965 else if (comp == NE_EXPR)
1969 /* If VR0 is completely to the left or completely to the right
1970 of VR1, they are always different. Notice that we need to
1971 make sure that both comparisons yield similar results to
1972 avoid comparing values that cannot be compared at
1974 cmp1 = compare_values (vr0->max, vr1->min);
1975 cmp2 = compare_values (vr0->min, vr1->max);
1976 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
1977 return boolean_true_node;
1979 /* If VR0 and VR1 represent a single value and are identical,
1981 else if (compare_values (vr0->min, vr0->max) == 0
1982 && compare_values (vr1->min, vr1->max) == 0
1983 && compare_values (vr0->min, vr1->min) == 0
1984 && compare_values (vr0->max, vr1->max) == 0)
1985 return boolean_false_node;
1987 /* Otherwise, they may or may not be different. */
1991 else if (comp == LT_EXPR || comp == LE_EXPR)
1995 /* If VR0 is to the left of VR1, return true. */
1996 tst = compare_values (vr0->max, vr1->min);
1997 if ((comp == LT_EXPR && tst == -1)
1998 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
1999 return boolean_true_node;
2001 /* If VR0 is to the right of VR1, return false. */
2002 tst = compare_values (vr0->min, vr1->max);
2003 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2004 || (comp == LE_EXPR && tst == 1))
2005 return boolean_false_node;
2007 /* Otherwise, we don't know. */
2015 /* Given a value range VR, a value VAL and a comparison code COMP, return
2016 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2017 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2018 always returns false. Return NULL_TREE if it is not always
2019 possible to determine the value of the comparison. */
2022 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val)
2024 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2027 /* Anti-ranges need to be handled separately. */
2028 if (vr->type == VR_ANTI_RANGE)
2030 /* For anti-ranges, the only predicates that we can compute at
2031 compile time are equality and inequality. */
2038 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2039 if (value_inside_range (val, vr) == 1)
2040 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2045 if (comp == EQ_EXPR)
2047 /* EQ_EXPR may only be computed if VR represents exactly
2049 if (compare_values (vr->min, vr->max) == 0)
2051 int cmp = compare_values (vr->min, val);
2053 return boolean_true_node;
2054 else if (cmp == -1 || cmp == 1 || cmp == 2)
2055 return boolean_false_node;
2057 else if (compare_values (val, vr->min) == -1
2058 || compare_values (vr->max, val) == -1)
2059 return boolean_false_node;
2063 else if (comp == NE_EXPR)
2065 /* If VAL is not inside VR, then they are always different. */
2066 if (compare_values (vr->max, val) == -1
2067 || compare_values (vr->min, val) == 1)
2068 return boolean_true_node;
2070 /* If VR represents exactly one value equal to VAL, then return
2072 if (compare_values (vr->min, vr->max) == 0
2073 && compare_values (vr->min, val) == 0)
2074 return boolean_false_node;
2076 /* Otherwise, they may or may not be different. */
2079 else if (comp == LT_EXPR || comp == LE_EXPR)
2083 /* If VR is to the left of VAL, return true. */
2084 tst = compare_values (vr->max, val);
2085 if ((comp == LT_EXPR && tst == -1)
2086 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2087 return boolean_true_node;
2089 /* If VR is to the right of VAL, return false. */
2090 tst = compare_values (vr->min, val);
2091 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2092 || (comp == LE_EXPR && tst == 1))
2093 return boolean_false_node;
2095 /* Otherwise, we don't know. */
2098 else if (comp == GT_EXPR || comp == GE_EXPR)
2102 /* If VR is to the right of VAL, return true. */
2103 tst = compare_values (vr->min, val);
2104 if ((comp == GT_EXPR && tst == 1)
2105 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
2106 return boolean_true_node;
2108 /* If VR is to the left of VAL, return false. */
2109 tst = compare_values (vr->max, val);
2110 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
2111 || (comp == GE_EXPR && tst == -1))
2112 return boolean_false_node;
2114 /* Otherwise, we don't know. */
2122 /* Debugging dumps. */
2124 void dump_value_range (FILE *, value_range_t *);
2125 void debug_value_range (value_range_t *);
2126 void dump_all_value_ranges (FILE *);
2127 void debug_all_value_ranges (void);
2128 void dump_vr_equiv (FILE *, bitmap);
2129 void debug_vr_equiv (bitmap);
2132 /* Dump value range VR to FILE. */
2135 dump_value_range (FILE *file, value_range_t *vr)
2138 fprintf (file, "[]");
2139 else if (vr->type == VR_UNDEFINED)
2140 fprintf (file, "UNDEFINED");
2141 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
2143 tree type = TREE_TYPE (vr->min);
2145 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
2147 if (INTEGRAL_TYPE_P (type)
2148 && !TYPE_UNSIGNED (type)
2149 && vr->min == TYPE_MIN_VALUE (type))
2150 fprintf (file, "-INF");
2152 print_generic_expr (file, vr->min, 0);
2154 fprintf (file, ", ");
2156 if (INTEGRAL_TYPE_P (type)
2157 && vr->max == TYPE_MAX_VALUE (type))
2158 fprintf (file, "+INF");
2160 print_generic_expr (file, vr->max, 0);
2162 fprintf (file, "]");
2169 fprintf (file, " EQUIVALENCES: { ");
2171 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
2173 print_generic_expr (file, ssa_name (i), 0);
2174 fprintf (file, " ");
2178 fprintf (file, "} (%u elements)", c);
2181 else if (vr->type == VR_VARYING)
2182 fprintf (file, "VARYING");
2184 fprintf (file, "INVALID RANGE");
2188 /* Dump value range VR to stderr. */
2191 debug_value_range (value_range_t *vr)
2193 dump_value_range (stderr, vr);
2197 /* Dump value ranges of all SSA_NAMEs to FILE. */
2200 dump_all_value_ranges (FILE *file)
2204 for (i = 0; i < num_ssa_names; i++)
2208 print_generic_expr (file, ssa_name (i), 0);
2209 fprintf (file, ": ");
2210 dump_value_range (file, vr_value[i]);
2211 fprintf (file, "\n");
2215 fprintf (file, "\n");
2219 /* Dump all value ranges to stderr. */
2222 debug_all_value_ranges (void)
2224 dump_all_value_ranges (stderr);
2228 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
2229 create a new SSA name N and return the assertion assignment
2230 'V = ASSERT_EXPR <V, V OP W>'. */
2233 build_assert_expr_for (tree cond, tree v)
2237 gcc_assert (TREE_CODE (v) == SSA_NAME);
2238 n = duplicate_ssa_name (v, NULL_TREE);
2240 if (COMPARISON_CLASS_P (cond))
2242 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
2243 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, a);
2245 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
2247 /* Given !V, build the assignment N = false. */
2248 tree op0 = TREE_OPERAND (cond, 0);
2249 gcc_assert (op0 == v);
2250 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_false_node);
2252 else if (TREE_CODE (cond) == SSA_NAME)
2254 /* Given V, build the assignment N = true. */
2255 gcc_assert (v == cond);
2256 assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_true_node);
2261 SSA_NAME_DEF_STMT (n) = assertion;
2263 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
2264 operand of the ASSERT_EXPR. Register the new name and the old one
2265 in the replacement table so that we can fix the SSA web after
2266 adding all the ASSERT_EXPRs. */
2267 register_new_name_mapping (n, v);
2273 /* Return false if EXPR is a predicate expression involving floating
2277 fp_predicate (tree expr)
2279 return (COMPARISON_CLASS_P (expr)
2280 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
2284 /* If the range of values taken by OP can be inferred after STMT executes,
2285 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2286 describes the inferred range. Return true if a range could be
2290 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
2293 *comp_code_p = ERROR_MARK;
2295 /* Do not attempt to infer anything in names that flow through
2297 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
2300 /* Similarly, don't infer anything from statements that may throw
2302 if (tree_could_throw_p (stmt))
2305 /* If STMT is the last statement of a basic block with no
2306 successors, there is no point inferring anything about any of its
2307 operands. We would not be able to find a proper insertion point
2308 for the assertion, anyway. */
2309 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
2312 if (POINTER_TYPE_P (TREE_TYPE (op)))
2315 unsigned num_uses, num_derefs;
2317 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
2318 if (num_derefs > 0 && flag_delete_null_pointer_checks)
2320 /* We can only assume that a pointer dereference will yield
2321 non-NULL if -fdelete-null-pointer-checks is enabled. */
2322 *val_p = build_int_cst (TREE_TYPE (op), 0);
2323 *comp_code_p = NE_EXPR;
2332 void dump_asserts_for (FILE *, tree);
2333 void debug_asserts_for (tree);
2334 void dump_all_asserts (FILE *);
2335 void debug_all_asserts (void);
2337 /* Dump all the registered assertions for NAME to FILE. */
2340 dump_asserts_for (FILE *file, tree name)
2344 fprintf (file, "Assertions to be inserted for ");
2345 print_generic_expr (file, name, 0);
2346 fprintf (file, "\n");
2348 loc = asserts_for[SSA_NAME_VERSION (name)];
2351 fprintf (file, "\t");
2352 print_generic_expr (file, bsi_stmt (loc->si), 0);
2353 fprintf (file, "\n\tBB #%d", loc->bb->index);
2356 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
2357 loc->e->dest->index);
2358 dump_edge_info (file, loc->e, 0);
2360 fprintf (file, "\n\tPREDICATE: ");
2361 print_generic_expr (file, name, 0);
2362 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
2363 print_generic_expr (file, loc->val, 0);
2364 fprintf (file, "\n\n");
2368 fprintf (file, "\n");
2372 /* Dump all the registered assertions for NAME to stderr. */
2375 debug_asserts_for (tree name)
2377 dump_asserts_for (stderr, name);
2381 /* Dump all the registered assertions for all the names to FILE. */
2384 dump_all_asserts (FILE *file)
2389 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
2390 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2391 dump_asserts_for (file, ssa_name (i));
2392 fprintf (file, "\n");
2396 /* Dump all the registered assertions for all the names to stderr. */
2399 debug_all_asserts (void)
2401 dump_all_asserts (stderr);
2405 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2406 'NAME COMP_CODE VAL' at a location that dominates block BB or
2407 E->DEST, then register this location as a possible insertion point
2408 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2410 BB, E and SI provide the exact insertion point for the new
2411 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2412 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2413 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2414 must not be NULL. */
2417 register_new_assert_for (tree name,
2418 enum tree_code comp_code,
2422 block_stmt_iterator si)
2424 assert_locus_t n, loc, last_loc;
2426 basic_block dest_bb;
2428 #if defined ENABLE_CHECKING
2429 gcc_assert (bb == NULL || e == NULL);
2432 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
2433 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
2436 /* The new assertion A will be inserted at BB or E. We need to
2437 determine if the new location is dominated by a previously
2438 registered location for A. If we are doing an edge insertion,
2439 assume that A will be inserted at E->DEST. Note that this is not
2442 If E is a critical edge, it will be split. But even if E is
2443 split, the new block will dominate the same set of blocks that
2446 The reverse, however, is not true, blocks dominated by E->DEST
2447 will not be dominated by the new block created to split E. So,
2448 if the insertion location is on a critical edge, we will not use
2449 the new location to move another assertion previously registered
2450 at a block dominated by E->DEST. */
2451 dest_bb = (bb) ? bb : e->dest;
2453 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2454 VAL at a block dominating DEST_BB, then we don't need to insert a new
2455 one. Similarly, if the same assertion already exists at a block
2456 dominated by DEST_BB and the new location is not on a critical
2457 edge, then update the existing location for the assertion (i.e.,
2458 move the assertion up in the dominance tree).
2460 Note, this is implemented as a simple linked list because there
2461 should not be more than a handful of assertions registered per
2462 name. If this becomes a performance problem, a table hashed by
2463 COMP_CODE and VAL could be implemented. */
2464 loc = asserts_for[SSA_NAME_VERSION (name)];
2469 if (loc->comp_code == comp_code
2471 || operand_equal_p (loc->val, val, 0)))
2473 /* If the assertion NAME COMP_CODE VAL has already been
2474 registered at a basic block that dominates DEST_BB, then
2475 we don't need to insert the same assertion again. Note
2476 that we don't check strict dominance here to avoid
2477 replicating the same assertion inside the same basic
2478 block more than once (e.g., when a pointer is
2479 dereferenced several times inside a block).
2481 An exception to this rule are edge insertions. If the
2482 new assertion is to be inserted on edge E, then it will
2483 dominate all the other insertions that we may want to
2484 insert in DEST_BB. So, if we are doing an edge
2485 insertion, don't do this dominance check. */
2487 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
2490 /* Otherwise, if E is not a critical edge and DEST_BB
2491 dominates the existing location for the assertion, move
2492 the assertion up in the dominance tree by updating its
2493 location information. */
2494 if ((e == NULL || !EDGE_CRITICAL_P (e))
2495 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
2504 /* Update the last node of the list and move to the next one. */
2509 /* If we didn't find an assertion already registered for
2510 NAME COMP_CODE VAL, add a new one at the end of the list of
2511 assertions associated with NAME. */
2512 n = xmalloc (sizeof (*n));
2516 n->comp_code = comp_code;
2523 asserts_for[SSA_NAME_VERSION (name)] = n;
2525 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
2529 /* Try to register an edge assertion for SSA name NAME on edge E for
2530 the conditional jump pointed to by SI. Return true if an assertion
2531 for NAME could be registered. */
2534 register_edge_assert_for (tree name, edge e, block_stmt_iterator si)
2537 enum tree_code comp_code;
2539 stmt = bsi_stmt (si);
2541 /* Do not attempt to infer anything in names that flow through
2543 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
2546 /* If NAME was not found in the sub-graph reachable from E, then
2547 there's nothing to do. */
2548 if (!TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
2551 /* We found a use of NAME in the sub-graph rooted at E->DEST.
2552 Register an assertion for NAME according to the value that NAME
2554 if (TREE_CODE (stmt) == COND_EXPR)
2556 /* If BB ends in a COND_EXPR then NAME then we should insert
2557 the original predicate on EDGE_TRUE_VALUE and the
2558 opposite predicate on EDGE_FALSE_VALUE. */
2559 tree cond = COND_EXPR_COND (stmt);
2560 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
2562 /* Predicates may be a single SSA name or NAME OP VAL. */
2565 /* If the predicate is a name, it must be NAME, in which
2566 case we create the predicate NAME == true or
2567 NAME == false accordingly. */
2568 comp_code = EQ_EXPR;
2569 val = (is_else_edge) ? boolean_false_node : boolean_true_node;
2573 /* Otherwise, we have a comparison of the form NAME COMP VAL
2574 or VAL COMP NAME. */
2575 if (name == TREE_OPERAND (cond, 1))
2577 /* If the predicate is of the form VAL COMP NAME, flip
2578 COMP around because we need to register NAME as the
2579 first operand in the predicate. */
2580 comp_code = swap_tree_comparison (TREE_CODE (cond));
2581 val = TREE_OPERAND (cond, 0);
2585 /* The comparison is of the form NAME COMP VAL, so the
2586 comparison code remains unchanged. */
2587 comp_code = TREE_CODE (cond);
2588 val = TREE_OPERAND (cond, 1);
2591 /* If we are inserting the assertion on the ELSE edge, we
2592 need to invert the sign comparison. */
2594 comp_code = invert_tree_comparison (comp_code, 0);
2596 /* Do not register always-false predicates. FIXME, this
2597 works around a limitation in fold() when dealing with
2598 enumerations. Given 'enum { N1, N2 } x;', fold will not
2599 fold 'if (x > N2)' to 'if (0)'. */
2600 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
2601 && (INTEGRAL_TYPE_P (TREE_TYPE (val))
2602 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (val))))
2604 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
2605 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
2607 if (comp_code == GT_EXPR && compare_values (val, max) == 0)
2610 if (comp_code == LT_EXPR && compare_values (val, min) == 0)
2617 /* FIXME. Handle SWITCH_EXPR. */
2621 register_new_assert_for (name, comp_code, val, NULL, e, si);
2626 static bool find_assert_locations (basic_block bb);
2628 /* Determine whether the outgoing edges of BB should receive an
2629 ASSERT_EXPR for each of the operands of BB's last statement. The
2630 last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2632 If any of the sub-graphs rooted at BB have an interesting use of
2633 the predicate operands, an assert location node is added to the
2634 list of assertions for the corresponding operands. */
2637 find_conditional_asserts (basic_block bb)
2640 block_stmt_iterator last_si;
2646 need_assert = false;
2647 last_si = bsi_last (bb);
2648 last = bsi_stmt (last_si);
2650 /* Look for uses of the operands in each of the sub-graphs
2651 rooted at BB. We need to check each of the outgoing edges
2652 separately, so that we know what kind of ASSERT_EXPR to
2654 FOR_EACH_EDGE (e, ei, bb->succs)
2659 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
2660 Otherwise, when we finish traversing each of the sub-graphs, we
2661 won't know whether the variables were found in the sub-graphs or
2662 if they had been found in a block upstream from BB. */
2663 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2664 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2666 /* Traverse the strictly dominated sub-graph rooted at E->DEST
2667 to determine if any of the operands in the conditional
2668 predicate are used. */
2670 need_assert |= find_assert_locations (e->dest);
2672 /* Register the necessary assertions for each operand in the
2673 conditional predicate. */
2674 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2675 need_assert |= register_edge_assert_for (op, e, last_si);
2678 /* Finally, indicate that we have found the operands in the
2680 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2681 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2687 /* Traverse all the statements in block BB looking for statements that
2688 may generate useful assertions for the SSA names in their operand.
2689 If a statement produces a useful assertion A for name N_i, then the
2690 list of assertions already generated for N_i is scanned to
2691 determine if A is actually needed.
2693 If N_i already had the assertion A at a location dominating the
2694 current location, then nothing needs to be done. Otherwise, the
2695 new location for A is recorded instead.
2697 1- For every statement S in BB, all the variables used by S are
2698 added to bitmap FOUND_IN_SUBGRAPH.
2700 2- If statement S uses an operand N in a way that exposes a known
2701 value range for N, then if N was not already generated by an
2702 ASSERT_EXPR, create a new assert location for N. For instance,
2703 if N is a pointer and the statement dereferences it, we can
2704 assume that N is not NULL.
2706 3- COND_EXPRs are a special case of #2. We can derive range
2707 information from the predicate but need to insert different
2708 ASSERT_EXPRs for each of the sub-graphs rooted at the
2709 conditional block. If the last statement of BB is a conditional
2710 expression of the form 'X op Y', then
2712 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
2714 b) If the conditional is the only entry point to the sub-graph
2715 corresponding to the THEN_CLAUSE, recurse into it. On
2716 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
2717 an ASSERT_EXPR is added for the corresponding variable.
2719 c) Repeat step (b) on the ELSE_CLAUSE.
2721 d) Mark X and Y in FOUND_IN_SUBGRAPH.
2730 In this case, an assertion on the THEN clause is useful to
2731 determine that 'a' is always 9 on that edge. However, an assertion
2732 on the ELSE clause would be unnecessary.
2734 4- If BB does not end in a conditional expression, then we recurse
2735 into BB's dominator children.
2737 At the end of the recursive traversal, every SSA name will have a
2738 list of locations where ASSERT_EXPRs should be added. When a new
2739 location for name N is found, it is registered by calling
2740 register_new_assert_for. That function keeps track of all the
2741 registered assertions to prevent adding unnecessary assertions.
2742 For instance, if a pointer P_4 is dereferenced more than once in a
2743 dominator tree, only the location dominating all the dereference of
2744 P_4 will receive an ASSERT_EXPR.
2746 If this function returns true, then it means that there are names
2747 for which we need to generate ASSERT_EXPRs. Those assertions are
2748 inserted by process_assert_insertions.
2750 TODO. Handle SWITCH_EXPR. */
2753 find_assert_locations (basic_block bb)
2755 block_stmt_iterator si;
2760 if (TEST_BIT (blocks_visited, bb->index))
2763 SET_BIT (blocks_visited, bb->index);
2765 need_assert = false;
2767 /* Traverse all PHI nodes in BB marking used operands. */
2768 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
2770 use_operand_p arg_p;
2773 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
2775 tree arg = USE_FROM_PTR (arg_p);
2776 if (TREE_CODE (arg) == SSA_NAME)
2778 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
2779 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
2784 /* Traverse all the statements in BB marking used names and looking
2785 for statements that may infer assertions for their used operands. */
2787 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
2792 stmt = bsi_stmt (si);
2794 /* See if we can derive an assertion for any of STMT's operands. */
2795 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
2798 enum tree_code comp_code;
2800 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
2801 the sub-graph of a conditional block, when we return from
2802 this recursive walk, our parent will use the
2803 FOUND_IN_SUBGRAPH bitset to determine if one of the
2804 operands it was looking for was present in the sub-graph. */
2805 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2807 /* If OP is used only once, namely in this STMT, don't
2808 bother creating an ASSERT_EXPR for it. Such an
2809 ASSERT_EXPR would do nothing but increase compile time.
2810 Experiments show that with this simple check, we can save
2811 more than 20% of ASSERT_EXPRs. */
2812 if (has_single_use (op))
2815 /* If OP is used in such a way that we can infer a value
2816 range for it, and we don't find a previous assertion for
2817 it, create a new assertion location node for OP. */
2818 if (infer_value_range (stmt, op, &comp_code, &value))
2820 register_new_assert_for (op, comp_code, value, bb, NULL, si);
2825 /* Remember the last statement of the block. */
2829 /* If BB's last statement is a conditional expression
2830 involving integer operands, recurse into each of the sub-graphs
2831 rooted at BB to determine if we need to add ASSERT_EXPRs. */
2833 && TREE_CODE (last) == COND_EXPR
2834 && !fp_predicate (COND_EXPR_COND (last))
2835 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
2836 need_assert |= find_conditional_asserts (bb);
2838 /* Recurse into the dominator children of BB. */
2839 for (son = first_dom_son (CDI_DOMINATORS, bb);
2841 son = next_dom_son (CDI_DOMINATORS, son))
2842 need_assert |= find_assert_locations (son);
2848 /* Create an ASSERT_EXPR for NAME and insert it in the location
2849 indicated by LOC. Return true if we made any edge insertions. */
2852 process_assert_insertions_for (tree name, assert_locus_t loc)
2854 /* Build the comparison expression NAME_i COMP_CODE VAL. */
2855 tree stmt, cond, assert_expr;
2859 cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
2860 assert_expr = build_assert_expr_for (cond, name);
2864 /* We have been asked to insert the assertion on an edge. This
2865 is used only by COND_EXPR and SWITCH_EXPR assertions. */
2866 #if defined ENABLE_CHECKING
2867 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
2868 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
2871 bsi_insert_on_edge (loc->e, assert_expr);
2875 /* Otherwise, we can insert right after LOC->SI iff the
2876 statement must not be the last statement in the block. */
2877 stmt = bsi_stmt (loc->si);
2878 if (!stmt_ends_bb_p (stmt))
2880 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
2884 /* If STMT must be the last statement in BB, we can only insert new
2885 assertions on the non-abnormal edge out of BB. Note that since
2886 STMT is not control flow, there may only be one non-abnormal edge
2888 FOR_EACH_EDGE (e, ei, loc->bb->succs)
2889 if (!(e->flags & EDGE_ABNORMAL))
2891 bsi_insert_on_edge (e, assert_expr);
2899 /* Process all the insertions registered for every name N_i registered
2900 in NEED_ASSERT_FOR. The list of assertions to be inserted are
2901 found in ASSERTS_FOR[i]. */
2904 process_assert_insertions (void)
2908 bool update_edges_p = false;
2909 int num_asserts = 0;
2911 if (dump_file && (dump_flags & TDF_DETAILS))
2912 dump_all_asserts (dump_file);
2914 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2916 assert_locus_t loc = asserts_for[i];
2921 assert_locus_t next = loc->next;
2922 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
2930 bsi_commit_edge_inserts ();
2932 if (dump_file && (dump_flags & TDF_STATS))
2933 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
2938 /* Traverse the flowgraph looking for conditional jumps to insert range
2939 expressions. These range expressions are meant to provide information
2940 to optimizations that need to reason in terms of value ranges. They
2941 will not be expanded into RTL. For instance, given:
2950 this pass will transform the code into:
2956 x = ASSERT_EXPR <x, x < y>
2961 y = ASSERT_EXPR <y, x <= y>
2965 The idea is that once copy and constant propagation have run, other
2966 optimizations will be able to determine what ranges of values can 'x'
2967 take in different paths of the code, simply by checking the reaching
2968 definition of 'x'. */
2971 insert_range_assertions (void)
2977 found_in_subgraph = sbitmap_alloc (num_ssa_names);
2978 sbitmap_zero (found_in_subgraph);
2980 blocks_visited = sbitmap_alloc (last_basic_block);
2981 sbitmap_zero (blocks_visited);
2983 need_assert_for = BITMAP_ALLOC (NULL);
2984 asserts_for = xmalloc (num_ssa_names * sizeof (assert_locus_t));
2985 memset (asserts_for, 0, num_ssa_names * sizeof (assert_locus_t));
2987 calculate_dominance_info (CDI_DOMINATORS);
2989 update_ssa_p = false;
2990 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2991 if (find_assert_locations (e->dest))
2992 update_ssa_p = true;
2996 process_assert_insertions ();
2997 update_ssa (TODO_update_ssa_no_phi);
3000 if (dump_file && (dump_flags & TDF_DETAILS))
3002 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
3003 dump_function_to_file (current_function_decl, dump_file, dump_flags);
3006 sbitmap_free (found_in_subgraph);
3008 BITMAP_FREE (need_assert_for);
3012 /* Convert range assertion expressions into the implied copies and
3013 copy propagate away the copies. Doing the trivial copy propagation
3014 here avoids the need to run the full copy propagation pass after
3017 FIXME, this will eventually lead to copy propagation removing the
3018 names that had useful range information attached to them. For
3019 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
3020 then N_i will have the range [3, +INF].
3022 However, by converting the assertion into the implied copy
3023 operation N_i = N_j, we will then copy-propagate N_j into the uses
3024 of N_i and lose the range information. We may want to hold on to
3025 ASSERT_EXPRs a little while longer as the ranges could be used in
3026 things like jump threading.
3028 The problem with keeping ASSERT_EXPRs around is that passes after
3029 VRP need to handle them appropriately.
3031 Another approach would be to make the range information a first
3032 class property of the SSA_NAME so that it can be queried from
3033 any pass. This is made somewhat more complex by the need for
3034 multiple ranges to be associated with one SSA_NAME. */
3037 remove_range_assertions (void)
3040 block_stmt_iterator si;
3042 /* Note that the BSI iterator bump happens at the bottom of the
3043 loop and no bump is necessary if we're removing the statement
3044 referenced by the current BSI. */
3046 for (si = bsi_start (bb); !bsi_end_p (si);)
3048 tree stmt = bsi_stmt (si);
3050 if (TREE_CODE (stmt) == MODIFY_EXPR
3051 && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
3053 tree rhs = TREE_OPERAND (stmt, 1);
3054 tree cond = fold (ASSERT_EXPR_COND (rhs));
3055 use_operand_p use_p;
3056 imm_use_iterator iter;
3058 gcc_assert (cond != boolean_false_node);
3059 TREE_OPERAND (stmt, 1) = ASSERT_EXPR_VAR (rhs);
3062 /* The statement is now a copy. Propagate the RHS into
3063 every use of the LHS. */
3064 FOR_EACH_IMM_USE_SAFE (use_p, iter, TREE_OPERAND (stmt, 0))
3066 SET_USE (use_p, ASSERT_EXPR_VAR (rhs));
3067 update_stmt (USE_STMT (use_p));
3070 /* And finally, remove the copy, it is not needed. */
3071 bsi_remove (&si, true);
3077 sbitmap_free (blocks_visited);
3081 /* Return true if STMT is interesting for VRP. */
3084 stmt_interesting_for_vrp (tree stmt)
3086 if (TREE_CODE (stmt) == PHI_NODE
3087 && is_gimple_reg (PHI_RESULT (stmt))
3088 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
3089 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
3091 else if (TREE_CODE (stmt) == MODIFY_EXPR)
3093 tree lhs = TREE_OPERAND (stmt, 0);
3095 if (TREE_CODE (lhs) == SSA_NAME
3096 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3097 || POINTER_TYPE_P (TREE_TYPE (lhs)))
3098 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3101 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3108 /* Initialize local data structures for VRP. */
3111 vrp_initialize (void)
3115 vr_value = xmalloc (num_ssa_names * sizeof (value_range_t *));
3116 memset (vr_value, 0, num_ssa_names * sizeof (value_range_t *));
3120 block_stmt_iterator si;
3123 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3125 if (!stmt_interesting_for_vrp (phi))
3127 tree lhs = PHI_RESULT (phi);
3128 set_value_range_to_varying (get_value_range (lhs));
3129 DONT_SIMULATE_AGAIN (phi) = true;
3132 DONT_SIMULATE_AGAIN (phi) = false;
3135 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3137 tree stmt = bsi_stmt (si);
3139 if (!stmt_interesting_for_vrp (stmt))
3143 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
3144 set_value_range_to_varying (get_value_range (def));
3145 DONT_SIMULATE_AGAIN (stmt) = true;
3149 DONT_SIMULATE_AGAIN (stmt) = false;
3156 /* Visit assignment STMT. If it produces an interesting range, record
3157 the SSA name in *OUTPUT_P. */
3159 static enum ssa_prop_result
3160 vrp_visit_assignment (tree stmt, tree *output_p)
3165 lhs = TREE_OPERAND (stmt, 0);
3166 rhs = TREE_OPERAND (stmt, 1);
3168 /* We only keep track of ranges in integral and pointer types. */
3169 if (TREE_CODE (lhs) == SSA_NAME
3170 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3171 || POINTER_TYPE_P (TREE_TYPE (lhs))))
3174 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3176 extract_range_from_expr (&new_vr, rhs);
3178 /* If STMT is inside a loop, we may be able to know something
3179 else about the range of LHS by examining scalar evolution
3181 if (cfg_loops && (l = loop_containing_stmt (stmt)))
3182 adjust_range_with_scev (&new_vr, l, stmt, lhs);
3184 if (update_value_range (lhs, &new_vr))
3188 if (dump_file && (dump_flags & TDF_DETAILS))
3190 fprintf (dump_file, "Found new range for ");
3191 print_generic_expr (dump_file, lhs, 0);
3192 fprintf (dump_file, ": ");
3193 dump_value_range (dump_file, &new_vr);
3194 fprintf (dump_file, "\n\n");
3197 if (new_vr.type == VR_VARYING)
3198 return SSA_PROP_VARYING;
3200 return SSA_PROP_INTERESTING;
3203 return SSA_PROP_NOT_INTERESTING;
3206 /* Every other statement produces no useful ranges. */
3207 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3208 set_value_range_to_varying (get_value_range (def));
3210 return SSA_PROP_VARYING;
3214 /* Compare all the value ranges for names equivalent to VAR with VAL
3215 using comparison code COMP. Return the same value returned by
3216 compare_range_with_value. */
3219 compare_name_with_value (enum tree_code comp, tree var, tree val)
3226 t = retval = NULL_TREE;
3228 /* Get the set of equivalences for VAR. */
3229 e = get_value_range (var)->equiv;
3231 /* Add VAR to its own set of equivalences so that VAR's value range
3232 is processed by this loop (otherwise, we would have to replicate
3233 the body of the loop just to check VAR's value range). */
3234 bitmap_set_bit (e, SSA_NAME_VERSION (var));
3236 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
3238 value_range_t equiv_vr = *(vr_value[i]);
3240 /* If name N_i does not have a valid range, use N_i as its own
3241 range. This allows us to compare against names that may
3242 have N_i in their ranges. */
3243 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
3245 equiv_vr.type = VR_RANGE;
3246 equiv_vr.min = ssa_name (i);
3247 equiv_vr.max = ssa_name (i);
3250 t = compare_range_with_value (comp, &equiv_vr, val);
3253 /* All the ranges should compare the same against VAL. */
3254 gcc_assert (retval == NULL || t == retval);
3259 /* Remove VAR from its own equivalence set. */
3260 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
3265 /* We couldn't find a non-NULL value for the predicate. */
3270 /* Given a comparison code COMP and names N1 and N2, compare all the
3271 ranges equivalent to N1 against all the ranges equivalent to N2
3272 to determine the value of N1 COMP N2. Return the same value
3273 returned by compare_ranges. */
3276 compare_names (enum tree_code comp, tree n1, tree n2)
3280 bitmap_iterator bi1, bi2;
3283 /* Compare the ranges of every name equivalent to N1 against the
3284 ranges of every name equivalent to N2. */
3285 e1 = get_value_range (n1)->equiv;
3286 e2 = get_value_range (n2)->equiv;
3288 /* Add N1 and N2 to their own set of equivalences to avoid
3289 duplicating the body of the loop just to check N1 and N2
3291 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
3292 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
3294 /* If the equivalence sets have a common intersection, then the two
3295 names can be compared without checking their ranges. */
3296 if (bitmap_intersect_p (e1, e2))
3298 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3299 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3301 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
3303 : boolean_false_node;
3306 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3307 N2 to their own set of equivalences to avoid duplicating the body
3308 of the loop just to check N1 and N2 ranges. */
3309 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
3311 value_range_t vr1 = *(vr_value[i1]);
3313 /* If the range is VARYING or UNDEFINED, use the name itself. */
3314 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
3316 vr1.type = VR_RANGE;
3317 vr1.min = ssa_name (i1);
3318 vr1.max = ssa_name (i1);
3321 t = retval = NULL_TREE;
3322 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
3324 value_range_t vr2 = *(vr_value[i2]);
3326 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
3328 vr2.type = VR_RANGE;
3329 vr2.min = ssa_name (i2);
3330 vr2.max = ssa_name (i2);
3333 t = compare_ranges (comp, &vr1, &vr2);
3336 /* All the ranges in the equivalent sets should compare
3338 gcc_assert (retval == NULL || t == retval);
3345 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3346 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3351 /* None of the equivalent ranges are useful in computing this
3353 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3354 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3359 /* Given a conditional predicate COND, try to determine if COND yields
3360 true or false based on the value ranges of its operands. Return
3361 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3362 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3363 NULL if the conditional cannot be evaluated at compile time.
3365 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3366 the operands in COND are used when trying to compute its value.
3367 This is only used during final substitution. During propagation,
3368 we only check the range of each variable and not its equivalents. */
3371 vrp_evaluate_conditional (tree cond, bool use_equiv_p)
3373 gcc_assert (TREE_CODE (cond) == SSA_NAME
3374 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
3376 if (TREE_CODE (cond) == SSA_NAME)
3382 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node);
3385 value_range_t *vr = get_value_range (cond);
3386 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node);
3389 /* If COND has a known boolean range, return it. */
3393 /* Otherwise, if COND has a symbolic range of exactly one value,
3395 vr = get_value_range (cond);
3396 if (vr->type == VR_RANGE && vr->min == vr->max)
3401 tree op0 = TREE_OPERAND (cond, 0);
3402 tree op1 = TREE_OPERAND (cond, 1);
3404 /* We only deal with integral and pointer types. */
3405 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
3406 && !POINTER_TYPE_P (TREE_TYPE (op0)))
3411 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
3412 return compare_names (TREE_CODE (cond), op0, op1);
3413 else if (TREE_CODE (op0) == SSA_NAME)
3414 return compare_name_with_value (TREE_CODE (cond), op0, op1);
3415 else if (TREE_CODE (op1) == SSA_NAME)
3416 return compare_name_with_value (
3417 swap_tree_comparison (TREE_CODE (cond)), op1, op0);
3421 value_range_t *vr0, *vr1;
3423 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
3424 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
3427 return compare_ranges (TREE_CODE (cond), vr0, vr1);
3428 else if (vr0 && vr1 == NULL)
3429 return compare_range_with_value (TREE_CODE (cond), vr0, op1);
3430 else if (vr0 == NULL && vr1)
3431 return compare_range_with_value (
3432 swap_tree_comparison (TREE_CODE (cond)), vr1, op0);
3436 /* Anything else cannot be computed statically. */
3441 /* Visit conditional statement STMT. If we can determine which edge
3442 will be taken out of STMT's basic block, record it in
3443 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3444 SSA_PROP_VARYING. */
3446 static enum ssa_prop_result
3447 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
3451 *taken_edge_p = NULL;
3453 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3454 add ASSERT_EXPRs for them. */
3455 if (TREE_CODE (stmt) == SWITCH_EXPR)
3456 return SSA_PROP_VARYING;
3458 cond = COND_EXPR_COND (stmt);
3460 if (dump_file && (dump_flags & TDF_DETAILS))
3465 fprintf (dump_file, "\nVisiting conditional with predicate: ");
3466 print_generic_expr (dump_file, cond, 0);
3467 fprintf (dump_file, "\nWith known ranges\n");
3469 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
3471 fprintf (dump_file, "\t");
3472 print_generic_expr (dump_file, use, 0);
3473 fprintf (dump_file, ": ");
3474 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
3477 fprintf (dump_file, "\n");
3480 /* Compute the value of the predicate COND by checking the known
3481 ranges of each of its operands.
3483 Note that we cannot evaluate all the equivalent ranges here
3484 because those ranges may not yet be final and with the current
3485 propagation strategy, we cannot determine when the value ranges
3486 of the names in the equivalence set have changed.
3488 For instance, given the following code fragment
3492 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3496 Assume that on the first visit to i_14, i_5 has the temporary
3497 range [8, 8] because the second argument to the PHI function is
3498 not yet executable. We derive the range ~[0, 0] for i_14 and the
3499 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3500 the first time, since i_14 is equivalent to the range [8, 8], we
3501 determine that the predicate is always false.
3503 On the next round of propagation, i_13 is determined to be
3504 VARYING, which causes i_5 to drop down to VARYING. So, another
3505 visit to i_14 is scheduled. In this second visit, we compute the
3506 exact same range and equivalence set for i_14, namely ~[0, 0] and
3507 { i_5 }. But we did not have the previous range for i_5
3508 registered, so vrp_visit_assignment thinks that the range for
3509 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3510 is not visited again, which stops propagation from visiting
3511 statements in the THEN clause of that if().
3513 To properly fix this we would need to keep the previous range
3514 value for the names in the equivalence set. This way we would've
3515 discovered that from one visit to the other i_5 changed from
3516 range [8, 8] to VR_VARYING.
3518 However, fixing this apparent limitation may not be worth the
3519 additional checking. Testing on several code bases (GCC, DLV,
3520 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3521 4 more predicates folded in SPEC. */
3522 val = vrp_evaluate_conditional (cond, false);
3524 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
3526 if (dump_file && (dump_flags & TDF_DETAILS))
3528 fprintf (dump_file, "\nPredicate evaluates to: ");
3529 if (val == NULL_TREE)
3530 fprintf (dump_file, "DON'T KNOW\n");
3532 print_generic_stmt (dump_file, val, 0);
3535 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
3539 /* Evaluate statement STMT. If the statement produces a useful range,
3540 return SSA_PROP_INTERESTING and record the SSA name with the
3541 interesting range into *OUTPUT_P.
3543 If STMT is a conditional branch and we can determine its truth
3544 value, the taken edge is recorded in *TAKEN_EDGE_P.
3546 If STMT produces a varying value, return SSA_PROP_VARYING. */
3548 static enum ssa_prop_result
3549 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
3555 if (dump_file && (dump_flags & TDF_DETAILS))
3557 fprintf (dump_file, "\nVisiting statement:\n");
3558 print_generic_stmt (dump_file, stmt, dump_flags);
3559 fprintf (dump_file, "\n");
3562 ann = stmt_ann (stmt);
3563 if (TREE_CODE (stmt) == MODIFY_EXPR
3564 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3565 return vrp_visit_assignment (stmt, output_p);
3566 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3567 return vrp_visit_cond_stmt (stmt, taken_edge_p);
3569 /* All other statements produce nothing of interest for VRP, so mark
3570 their outputs varying and prevent further simulation. */
3571 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3572 set_value_range_to_varying (get_value_range (def));
3574 return SSA_PROP_VARYING;
3578 /* Meet operation for value ranges. Given two value ranges VR0 and
3579 VR1, store in VR0 the result of meeting VR0 and VR1.
3581 The meeting rules are as follows:
3583 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
3585 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
3586 union of VR0 and VR1. */
3589 vrp_meet (value_range_t *vr0, value_range_t *vr1)
3591 if (vr0->type == VR_UNDEFINED)
3593 copy_value_range (vr0, vr1);
3597 if (vr1->type == VR_UNDEFINED)
3599 /* Nothing to do. VR0 already has the resulting range. */
3603 if (vr0->type == VR_VARYING)
3605 /* Nothing to do. VR0 already has the resulting range. */
3609 if (vr1->type == VR_VARYING)
3611 set_value_range_to_varying (vr0);
3615 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
3617 /* If VR0 and VR1 have a non-empty intersection, compute the
3618 union of both ranges. */
3619 if (value_ranges_intersect_p (vr0, vr1))
3624 /* The lower limit of the new range is the minimum of the
3625 two ranges. If they cannot be compared, the result is
3627 cmp = compare_values (vr0->min, vr1->min);
3628 if (cmp == 0 || cmp == 1)
3634 set_value_range_to_varying (vr0);
3638 /* Similarly, the upper limit of the new range is the
3639 maximum of the two ranges. If they cannot be compared,
3640 the result is VARYING. */
3641 cmp = compare_values (vr0->max, vr1->max);
3642 if (cmp == 0 || cmp == -1)
3648 set_value_range_to_varying (vr0);
3652 /* The resulting set of equivalences is the intersection of
3654 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3655 bitmap_and_into (vr0->equiv, vr1->equiv);
3656 else if (vr0->equiv && !vr1->equiv)
3657 bitmap_clear (vr0->equiv);
3659 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
3664 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
3666 /* Two anti-ranges meet only if they are both identical. */
3667 if (compare_values (vr0->min, vr1->min) == 0
3668 && compare_values (vr0->max, vr1->max) == 0
3669 && compare_values (vr0->min, vr0->max) == 0)
3671 /* The resulting set of equivalences is the intersection of
3673 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3674 bitmap_and_into (vr0->equiv, vr1->equiv);
3675 else if (vr0->equiv && !vr1->equiv)
3676 bitmap_clear (vr0->equiv);
3681 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
3683 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
3684 meet only if the ranges have an empty intersection. The
3685 result of the meet operation is the anti-range. */
3686 if (!symbolic_range_p (vr0)
3687 && !symbolic_range_p (vr1)
3688 && !value_ranges_intersect_p (vr0, vr1))
3690 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
3691 set. We need to compute the intersection of the two
3692 equivalence sets. */
3693 if (vr1->type == VR_ANTI_RANGE)
3694 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
3696 /* The resulting set of equivalences is the intersection of
3698 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3699 bitmap_and_into (vr0->equiv, vr1->equiv);
3700 else if (vr0->equiv && !vr1->equiv)
3701 bitmap_clear (vr0->equiv);
3712 /* The two range VR0 and VR1 do not meet. Before giving up and
3713 setting the result to VARYING, see if we can at least derive a
3714 useful anti-range. FIXME, all this nonsense about distinguishing
3715 anti-ranges from ranges is necessary because of the odd
3716 semantics of range_includes_zero_p and friends. */
3717 if (!symbolic_range_p (vr0)
3718 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
3719 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
3720 && !symbolic_range_p (vr1)
3721 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
3722 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
3724 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
3726 /* Since this meet operation did not result from the meeting of
3727 two equivalent names, VR0 cannot have any equivalences. */
3729 bitmap_clear (vr0->equiv);
3732 set_value_range_to_varying (vr0);
3736 /* Visit all arguments for PHI node PHI that flow through executable
3737 edges. If a valid value range can be derived from all the incoming
3738 value ranges, set a new range for the LHS of PHI. */
3740 static enum ssa_prop_result
3741 vrp_visit_phi_node (tree phi)
3744 tree lhs = PHI_RESULT (phi);
3745 value_range_t *lhs_vr = get_value_range (lhs);
3746 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3748 copy_value_range (&vr_result, lhs_vr);
3750 if (dump_file && (dump_flags & TDF_DETAILS))
3752 fprintf (dump_file, "\nVisiting PHI node: ");
3753 print_generic_expr (dump_file, phi, dump_flags);
3756 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
3758 edge e = PHI_ARG_EDGE (phi, i);
3760 if (dump_file && (dump_flags & TDF_DETAILS))
3763 "\n Argument #%d (%d -> %d %sexecutable)\n",
3764 i, e->src->index, e->dest->index,
3765 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
3768 if (e->flags & EDGE_EXECUTABLE)
3770 tree arg = PHI_ARG_DEF (phi, i);
3771 value_range_t vr_arg;
3773 if (TREE_CODE (arg) == SSA_NAME)
3774 vr_arg = *(get_value_range (arg));
3777 vr_arg.type = VR_RANGE;
3780 vr_arg.equiv = NULL;
3783 if (dump_file && (dump_flags & TDF_DETAILS))
3785 fprintf (dump_file, "\t");
3786 print_generic_expr (dump_file, arg, dump_flags);
3787 fprintf (dump_file, "\n\tValue: ");
3788 dump_value_range (dump_file, &vr_arg);
3789 fprintf (dump_file, "\n");
3792 vrp_meet (&vr_result, &vr_arg);
3794 if (vr_result.type == VR_VARYING)
3799 if (vr_result.type == VR_VARYING)
3802 /* To prevent infinite iterations in the algorithm, derive ranges
3803 when the new value is slightly bigger or smaller than the
3805 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE)
3807 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
3809 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
3810 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
3812 /* If the new minimum is smaller or larger than the previous
3813 one, go all the way to -INF. In the first case, to avoid
3814 iterating millions of times to reach -INF, and in the
3815 other case to avoid infinite bouncing between different
3817 if (cmp_min > 0 || cmp_min < 0)
3818 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
3820 /* Similarly, if the new maximum is smaller or larger than
3821 the previous one, go all the way to +INF. */
3822 if (cmp_max < 0 || cmp_max > 0)
3823 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
3825 /* If we ended up with a (-INF, +INF) range, set it to
3827 if (vr_result.min == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))
3828 && vr_result.max == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)))
3833 /* If the new range is different than the previous value, keep
3835 if (update_value_range (lhs, &vr_result))
3836 return SSA_PROP_INTERESTING;
3838 /* Nothing changed, don't add outgoing edges. */
3839 return SSA_PROP_NOT_INTERESTING;
3841 /* No match found. Set the LHS to VARYING. */
3843 set_value_range_to_varying (lhs_vr);
3844 return SSA_PROP_VARYING;
3847 /* Simplify a division or modulo operator to a right shift or
3848 bitwise and if the first operand is unsigned or is greater
3849 than zero and the second operand is an exact power of two. */
3852 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
3855 tree op = TREE_OPERAND (rhs, 0);
3856 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
3858 if (TYPE_UNSIGNED (TREE_TYPE (op)))
3860 val = integer_one_node;
3864 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node);
3867 if (val && integer_onep (val))
3870 tree op0 = TREE_OPERAND (rhs, 0);
3871 tree op1 = TREE_OPERAND (rhs, 1);
3873 if (rhs_code == TRUNC_DIV_EXPR)
3875 t = build_int_cst (NULL_TREE, tree_log2 (op1));
3876 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
3880 t = build_int_cst (TREE_TYPE (op1), 1);
3881 t = int_const_binop (MINUS_EXPR, op1, t, 0);
3882 t = fold_convert (TREE_TYPE (op0), t);
3883 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
3886 TREE_OPERAND (stmt, 1) = t;
3891 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
3892 ABS_EXPR. If the operand is <= 0, then simplify the
3893 ABS_EXPR into a NEGATE_EXPR. */
3896 simplify_abs_using_ranges (tree stmt, tree rhs)
3899 tree op = TREE_OPERAND (rhs, 0);
3900 tree type = TREE_TYPE (op);
3901 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
3903 if (TYPE_UNSIGNED (type))
3905 val = integer_zero_node;
3909 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node);
3912 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node);
3916 if (integer_zerop (val))
3917 val = integer_one_node;
3918 else if (integer_onep (val))
3919 val = integer_zero_node;
3924 && (integer_onep (val) || integer_zerop (val)))
3928 if (integer_onep (val))
3929 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
3933 TREE_OPERAND (stmt, 1) = t;
3939 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
3940 a known value range VR.
3942 If there is one and only one value which will satisfy the
3943 conditional, then return that value. Else return NULL. */
3946 test_for_singularity (enum tree_code cond_code, tree op0,
3947 tree op1, value_range_t *vr)
3952 /* Extract minimum/maximum values which satisfy the
3953 the conditional as it was written. */
3954 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
3956 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
3959 if (cond_code == LT_EXPR)
3961 tree one = build_int_cst (TREE_TYPE (op0), 1);
3962 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
3965 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
3967 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
3970 if (cond_code == GT_EXPR)
3972 tree one = build_int_cst (TREE_TYPE (op0), 1);
3973 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
3977 /* Now refine the minimum and maximum values using any
3978 value range information we have for op0. */
3981 if (compare_values (vr->min, min) == -1)
3985 if (compare_values (vr->max, max) == 1)
3990 /* If the new min/max values have converged to a single value,
3991 then there is only one value which can satisfy the condition,
3992 return that value. */
3993 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
3999 /* Simplify a conditional using a relational operator to an equality
4000 test if the range information indicates only one value can satisfy
4001 the original conditional. */
4004 simplify_cond_using_ranges (tree stmt)
4006 tree cond = COND_EXPR_COND (stmt);
4007 tree op0 = TREE_OPERAND (cond, 0);
4008 tree op1 = TREE_OPERAND (cond, 1);
4009 enum tree_code cond_code = TREE_CODE (cond);
4011 if (cond_code != NE_EXPR
4012 && cond_code != EQ_EXPR
4013 && TREE_CODE (op0) == SSA_NAME
4014 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
4015 && is_gimple_min_invariant (op1))
4017 value_range_t *vr = get_value_range (op0);
4019 /* If we have range information for OP0, then we might be
4020 able to simplify this conditional. */
4021 if (vr->type == VR_RANGE)
4023 tree new = test_for_singularity (cond_code, op0, op1, vr);
4029 fprintf (dump_file, "Simplified relational ");
4030 print_generic_expr (dump_file, cond, 0);
4031 fprintf (dump_file, " into ");
4034 COND_EXPR_COND (stmt)
4035 = build2 (EQ_EXPR, boolean_type_node, op0, new);
4040 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4041 fprintf (dump_file, "\n");
4047 /* Try again after inverting the condition. We only deal
4048 with integral types here, so no need to worry about
4049 issues with inverting FP comparisons. */
4050 cond_code = invert_tree_comparison (cond_code, false);
4051 new = test_for_singularity (cond_code, op0, op1, vr);
4057 fprintf (dump_file, "Simplified relational ");
4058 print_generic_expr (dump_file, cond, 0);
4059 fprintf (dump_file, " into ");
4062 COND_EXPR_COND (stmt)
4063 = build2 (NE_EXPR, boolean_type_node, op0, new);
4068 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4069 fprintf (dump_file, "\n");
4078 /* Simplify STMT using ranges if possible. */
4081 simplify_stmt_using_ranges (tree stmt)
4083 if (TREE_CODE (stmt) == MODIFY_EXPR)
4085 tree rhs = TREE_OPERAND (stmt, 1);
4086 enum tree_code rhs_code = TREE_CODE (rhs);
4088 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
4089 and BIT_AND_EXPR respectively if the first operand is greater
4090 than zero and the second operand is an exact power of two. */
4091 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
4092 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
4093 && integer_pow2p (TREE_OPERAND (rhs, 1)))
4094 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
4096 /* Transform ABS (X) into X or -X as appropriate. */
4097 if (rhs_code == ABS_EXPR
4098 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
4099 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
4100 simplify_abs_using_ranges (stmt, rhs);
4102 else if (TREE_CODE (stmt) == COND_EXPR
4103 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
4105 simplify_cond_using_ranges (stmt);
4111 /* Traverse all the blocks folding conditionals with known ranges. */
4117 prop_value_t *single_val_range;
4118 bool do_value_subst_p;
4122 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
4123 dump_all_value_ranges (dump_file);
4124 fprintf (dump_file, "\n");
4127 /* We may have ended with ranges that have exactly one value. Those
4128 values can be substituted as any other copy/const propagated
4129 value using substitute_and_fold. */
4130 single_val_range = xmalloc (num_ssa_names * sizeof (*single_val_range));
4131 memset (single_val_range, 0, num_ssa_names * sizeof (*single_val_range));
4133 do_value_subst_p = false;
4134 for (i = 0; i < num_ssa_names; i++)
4136 && vr_value[i]->type == VR_RANGE
4137 && vr_value[i]->min == vr_value[i]->max)
4139 single_val_range[i].value = vr_value[i]->min;
4140 do_value_subst_p = true;
4143 if (!do_value_subst_p)
4145 /* We found no single-valued ranges, don't waste time trying to
4146 do single value substitution in substitute_and_fold. */
4147 free (single_val_range);
4148 single_val_range = NULL;
4151 substitute_and_fold (single_val_range, true);
4153 /* Free allocated memory. */
4154 for (i = 0; i < num_ssa_names; i++)
4157 BITMAP_FREE (vr_value[i]->equiv);
4161 free (single_val_range);
4166 /* Main entry point to VRP (Value Range Propagation). This pass is
4167 loosely based on J. R. C. Patterson, ``Accurate Static Branch
4168 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
4169 Programming Language Design and Implementation, pp. 67-78, 1995.
4170 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
4172 This is essentially an SSA-CCP pass modified to deal with ranges
4173 instead of constants.
4175 While propagating ranges, we may find that two or more SSA name
4176 have equivalent, though distinct ranges. For instance,
4179 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
4181 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
4185 In the code above, pointer p_5 has range [q_2, q_2], but from the
4186 code we can also determine that p_5 cannot be NULL and, if q_2 had
4187 a non-varying range, p_5's range should also be compatible with it.
4189 These equivalences are created by two expressions: ASSERT_EXPR and
4190 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
4191 result of another assertion, then we can use the fact that p_5 and
4192 p_4 are equivalent when evaluating p_5's range.
4194 Together with value ranges, we also propagate these equivalences
4195 between names so that we can take advantage of information from
4196 multiple ranges when doing final replacement. Note that this
4197 equivalency relation is transitive but not symmetric.
4199 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
4200 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
4201 in contexts where that assertion does not hold (e.g., in line 6).
4203 TODO, the main difference between this pass and Patterson's is that
4204 we do not propagate edge probabilities. We only compute whether
4205 edges can be taken or not. That is, instead of having a spectrum
4206 of jump probabilities between 0 and 1, we only deal with 0, 1 and
4207 DON'T KNOW. In the future, it may be worthwhile to propagate
4208 probabilities to aid branch prediction. */
4213 insert_range_assertions ();
4215 cfg_loops = loop_optimizer_init (NULL);
4217 scev_initialize (cfg_loops);
4220 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
4226 loop_optimizer_finalize (cfg_loops, NULL);
4227 current_loops = NULL;
4230 remove_range_assertions ();
4236 return flag_tree_vrp != 0;
4239 struct tree_opt_pass pass_vrp =
4242 gate_vrp, /* gate */
4243 execute_vrp, /* execute */
4246 0, /* static_pass_number */
4247 TV_TREE_VRP, /* tv_id */
4248 PROP_ssa | PROP_alias, /* properties_required */
4249 0, /* properties_provided */
4250 0, /* properties_destroyed */
4251 0, /* todo_flags_start */
4256 | TODO_update_ssa, /* todo_flags_finish */