1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
24 #include "coretypes.h"
29 #include "basic-block.h"
30 #include "tree-flow.h"
31 #include "tree-pass.h"
32 #include "tree-dump.h"
34 #include "diagnostic.h"
36 #include "tree-scalar-evolution.h"
37 #include "tree-ssa-propagate.h"
38 #include "tree-chrec.h"
40 /* Set of SSA names found during the dominator traversal of a
41 sub-graph in find_assert_locations. */
42 static sbitmap found_in_subgraph;
44 /* Loop structure of the program. Used to analyze scalar evolutions
45 inside adjust_range_with_scev. */
46 static struct loops *cfg_loops;
48 /* Local functions. */
49 static int compare_values (tree val1, tree val2);
51 /* Location information for ASSERT_EXPRs. Each instance of this
52 structure describes an ASSERT_EXPR for an SSA name. Since a single
53 SSA name may have more than one assertion associated with it, these
54 locations are kept in a linked list attached to the corresponding
58 /* Basic block where the assertion would be inserted. */
61 /* Some assertions need to be inserted on an edge (e.g., assertions
62 generated by COND_EXPRs). In those cases, BB will be NULL. */
65 /* Pointer to the statement that generated this assertion. */
66 block_stmt_iterator si;
68 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
69 enum tree_code comp_code;
71 /* Value being compared against. */
74 /* Next node in the linked list. */
75 struct assert_locus_d *next;
78 typedef struct assert_locus_d *assert_locus_t;
80 /* If bit I is present, it means that SSA name N_i has a list of
81 assertions that should be inserted in the IL. */
82 static bitmap need_assert_for;
84 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
85 holds a list of ASSERT_LOCUS_T nodes that describe where
86 ASSERT_EXPRs for SSA name N_I should be inserted. */
87 static assert_locus_t *asserts_for;
89 /* Set of blocks visited in find_assert_locations. Used to avoid
90 visiting the same block more than once. */
91 static sbitmap blocks_visited;
93 /* Value range array. After propagation, VR_VALUE[I] holds the range
94 of values that SSA name N_I may take. */
95 static value_range_t **vr_value;
98 /* Return true if ARG is marked with the nonnull attribute in the
99 current function signature. */
102 nonnull_arg_p (tree arg)
104 tree t, attrs, fntype;
105 unsigned HOST_WIDE_INT arg_num;
107 gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
109 fntype = TREE_TYPE (current_function_decl);
110 attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype));
112 /* If "nonnull" wasn't specified, we know nothing about the argument. */
113 if (attrs == NULL_TREE)
116 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
117 if (TREE_VALUE (attrs) == NULL_TREE)
120 /* Get the position number for ARG in the function signature. */
121 for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl);
123 t = TREE_CHAIN (t), arg_num++)
129 gcc_assert (t == arg);
131 /* Now see if ARG_NUM is mentioned in the nonnull list. */
132 for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
134 if (compare_tree_int (TREE_VALUE (t), arg_num) == 0)
142 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
145 set_value_range (value_range_t *vr, enum value_range_type t, tree min,
146 tree max, bitmap equiv)
148 #if defined ENABLE_CHECKING
149 /* Check the validity of the range. */
150 if (t == VR_RANGE || t == VR_ANTI_RANGE)
154 gcc_assert (min && max);
156 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
157 gcc_assert (min != TYPE_MIN_VALUE (TREE_TYPE (min))
158 || max != TYPE_MAX_VALUE (TREE_TYPE (max)));
160 cmp = compare_values (min, max);
161 gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
164 if (t == VR_UNDEFINED || t == VR_VARYING)
165 gcc_assert (min == NULL_TREE && max == NULL_TREE);
167 if (t == VR_UNDEFINED || t == VR_VARYING)
168 gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
175 /* Since updating the equivalence set involves deep copying the
176 bitmaps, only do it if absolutely necessary. */
177 if (vr->equiv == NULL)
178 vr->equiv = BITMAP_ALLOC (NULL);
180 if (equiv != vr->equiv)
182 if (equiv && !bitmap_empty_p (equiv))
183 bitmap_copy (vr->equiv, equiv);
185 bitmap_clear (vr->equiv);
190 /* Copy value range FROM into value range TO. */
193 copy_value_range (value_range_t *to, value_range_t *from)
195 set_value_range (to, from->type, from->min, from->max, from->equiv);
199 /* Set value range VR to a non-NULL range of type TYPE. */
202 set_value_range_to_nonnull (value_range_t *vr, tree type)
204 tree zero = build_int_cst (type, 0);
205 set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
209 /* Set value range VR to a NULL range of type TYPE. */
212 set_value_range_to_null (value_range_t *vr, tree type)
214 tree zero = build_int_cst (type, 0);
215 set_value_range (vr, VR_RANGE, zero, zero, vr->equiv);
219 /* Set value range VR to VR_VARYING. */
222 set_value_range_to_varying (value_range_t *vr)
224 vr->type = VR_VARYING;
225 vr->min = vr->max = NULL_TREE;
227 bitmap_clear (vr->equiv);
231 /* Set value range VR to VR_UNDEFINED. */
234 set_value_range_to_undefined (value_range_t *vr)
236 vr->type = VR_UNDEFINED;
237 vr->min = vr->max = NULL_TREE;
239 bitmap_clear (vr->equiv);
243 /* Return value range information for VAR. Create an empty range
246 static value_range_t *
247 get_value_range (tree var)
251 unsigned ver = SSA_NAME_VERSION (var);
257 /* Create a default value range. */
258 vr_value[ver] = vr = xmalloc (sizeof (*vr));
259 memset (vr, 0, sizeof (*vr));
261 /* Allocate an equivalence set. */
262 vr->equiv = BITMAP_ALLOC (NULL);
264 /* If VAR is a default definition, the variable can take any value
266 sym = SSA_NAME_VAR (var);
267 if (var == default_def (sym))
269 /* Try to use the "nonnull" attribute to create ~[0, 0]
270 anti-ranges for pointers. Note that this is only valid with
271 default definitions of PARM_DECLs. */
272 if (TREE_CODE (sym) == PARM_DECL
273 && POINTER_TYPE_P (TREE_TYPE (sym))
274 && nonnull_arg_p (sym))
275 set_value_range_to_nonnull (vr, TREE_TYPE (sym));
277 set_value_range_to_varying (vr);
284 /* Update the value range and equivalence set for variable VAR to
285 NEW_VR. Return true if NEW_VR is different from VAR's previous
288 NOTE: This function assumes that NEW_VR is a temporary value range
289 object created for the sole purpose of updating VAR's range. The
290 storage used by the equivalence set from NEW_VR will be freed by
291 this function. Do not call update_value_range when NEW_VR
292 is the range object associated with another SSA name. */
295 update_value_range (tree var, value_range_t *new_vr)
297 value_range_t *old_vr;
300 /* Update the value range, if necessary. */
301 old_vr = get_value_range (var);
302 is_new = old_vr->type != new_vr->type
303 || old_vr->min != new_vr->min
304 || old_vr->max != new_vr->max
305 || (old_vr->equiv == NULL && new_vr->equiv)
306 || (old_vr->equiv && new_vr->equiv == NULL)
307 || (!bitmap_equal_p (old_vr->equiv, new_vr->equiv));
310 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
313 BITMAP_FREE (new_vr->equiv);
314 new_vr->equiv = NULL;
320 /* Add VAR and VAR's equivalence set to EQUIV. */
323 add_equivalence (bitmap equiv, tree var)
325 unsigned ver = SSA_NAME_VERSION (var);
326 value_range_t *vr = vr_value[ver];
328 bitmap_set_bit (equiv, ver);
330 bitmap_ior_into (equiv, vr->equiv);
334 /* Return true if VR is ~[0, 0]. */
337 range_is_nonnull (value_range_t *vr)
339 return vr->type == VR_ANTI_RANGE
340 && integer_zerop (vr->min)
341 && integer_zerop (vr->max);
345 /* Return true if VR is [0, 0]. */
348 range_is_null (value_range_t *vr)
350 return vr->type == VR_RANGE
351 && integer_zerop (vr->min)
352 && integer_zerop (vr->max);
356 /* Return true if value range VR involves at least one symbol. */
359 symbolic_range_p (value_range_t *vr)
361 return (!is_gimple_min_invariant (vr->min)
362 || !is_gimple_min_invariant (vr->max));
366 /* Like tree_expr_nonzero_p, but this function uses value ranges
370 vrp_expr_computes_nonzero (tree expr)
372 if (tree_expr_nonzero_p (expr))
375 /* If we have an expression of the form &X->a, then the expression
376 is nonnull if X is nonnull. */
377 if (TREE_CODE (expr) == ADDR_EXPR)
379 tree base = get_base_address (TREE_OPERAND (expr, 0));
381 if (base != NULL_TREE
382 && TREE_CODE (base) == INDIRECT_REF
383 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
385 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
386 if (range_is_nonnull (vr))
395 /* Compare two values VAL1 and VAL2. Return
397 -2 if VAL1 and VAL2 cannot be compared at compile-time,
400 +1 if VAL1 > VAL2, and
403 This is similar to tree_int_cst_compare but supports pointer values
404 and values that cannot be compared at compile time. */
407 compare_values (tree val1, tree val2)
412 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
414 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
415 == POINTER_TYPE_P (TREE_TYPE (val2)));
417 /* Do some limited symbolic comparisons. */
418 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
420 /* We can determine some comparisons against +INF and -INF even
421 if the other value is an expression. */
422 if (val1 == TYPE_MAX_VALUE (TREE_TYPE (val1))
423 && TREE_CODE (val2) == MINUS_EXPR)
425 /* +INF > NAME - CST. */
428 else if (val1 == TYPE_MIN_VALUE (TREE_TYPE (val1))
429 && TREE_CODE (val2) == PLUS_EXPR)
431 /* -INF < NAME + CST. */
434 else if (TREE_CODE (val1) == MINUS_EXPR
435 && val2 == TYPE_MAX_VALUE (TREE_TYPE (val2)))
437 /* NAME - CST < +INF. */
440 else if (TREE_CODE (val1) == PLUS_EXPR
441 && val2 == TYPE_MIN_VALUE (TREE_TYPE (val2)))
443 /* NAME + CST > -INF. */
448 if ((TREE_CODE (val1) == SSA_NAME
449 || TREE_CODE (val1) == PLUS_EXPR
450 || TREE_CODE (val1) == MINUS_EXPR)
451 && (TREE_CODE (val2) == SSA_NAME
452 || TREE_CODE (val2) == PLUS_EXPR
453 || TREE_CODE (val2) == MINUS_EXPR))
457 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
458 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
459 same name, return -2. */
460 if (TREE_CODE (val1) == SSA_NAME)
467 n1 = TREE_OPERAND (val1, 0);
468 c1 = TREE_OPERAND (val1, 1);
471 if (TREE_CODE (val2) == SSA_NAME)
478 n2 = TREE_OPERAND (val2, 0);
479 c2 = TREE_OPERAND (val2, 1);
482 /* Both values must use the same name. */
486 if (TREE_CODE (val1) == SSA_NAME)
488 if (TREE_CODE (val2) == SSA_NAME)
491 else if (TREE_CODE (val2) == PLUS_EXPR)
492 /* NAME < NAME + CST */
494 else if (TREE_CODE (val2) == MINUS_EXPR)
495 /* NAME > NAME - CST */
498 else if (TREE_CODE (val1) == PLUS_EXPR)
500 if (TREE_CODE (val2) == SSA_NAME)
501 /* NAME + CST > NAME */
503 else if (TREE_CODE (val2) == PLUS_EXPR)
504 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
505 return compare_values (c1, c2);
506 else if (TREE_CODE (val2) == MINUS_EXPR)
507 /* NAME + CST1 > NAME - CST2 */
510 else if (TREE_CODE (val1) == MINUS_EXPR)
512 if (TREE_CODE (val2) == SSA_NAME)
513 /* NAME - CST < NAME */
515 else if (TREE_CODE (val2) == PLUS_EXPR)
516 /* NAME - CST1 < NAME + CST2 */
518 else if (TREE_CODE (val2) == MINUS_EXPR)
519 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
520 C1 and C2 are swapped in the call to compare_values. */
521 return compare_values (c2, c1);
527 /* We cannot compare non-constants. */
528 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
531 /* We cannot compare overflowed values. */
532 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
535 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
536 return tree_int_cst_compare (val1, val2);
541 /* First see if VAL1 and VAL2 are not the same. */
542 if (val1 == val2 || operand_equal_p (val1, val2, 0))
545 /* If VAL1 is a lower address than VAL2, return -1. */
546 t = fold_binary (LT_EXPR, boolean_type_node, val1, val2);
547 if (t == boolean_true_node)
550 /* If VAL1 is a higher address than VAL2, return +1. */
551 t = fold_binary (GT_EXPR, boolean_type_node, val1, val2);
552 if (t == boolean_true_node)
555 /* If VAL1 is different than VAL2, return +2. */
556 t = fold_binary (NE_EXPR, boolean_type_node, val1, val2);
557 if (t == boolean_true_node)
565 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
566 0 if VAL is not inside VR,
567 -2 if we cannot tell either way. */
570 value_inside_range (tree val, value_range_t *vr)
574 cmp1 = compare_values (val, vr->min);
575 if (cmp1 == -2 || cmp1 == 2)
578 cmp2 = compare_values (val, vr->max);
579 if (cmp2 == -2 || cmp2 == 2)
582 return (cmp1 == 0 || cmp1 == 1) && (cmp2 == -1 || cmp2 == 0);
586 /* Return true if value ranges VR0 and VR1 have a non-empty
590 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
592 return (value_inside_range (vr1->min, vr0) == 1
593 || value_inside_range (vr1->max, vr0) == 1
594 || value_inside_range (vr0->min, vr1) == 1
595 || value_inside_range (vr0->max, vr1) == 1);
599 /* Return true if VR includes the value zero, false otherwise. */
602 range_includes_zero_p (value_range_t *vr)
606 gcc_assert (vr->type != VR_UNDEFINED
607 && vr->type != VR_VARYING
608 && !symbolic_range_p (vr));
610 zero = build_int_cst (TREE_TYPE (vr->min), 0);
611 return (value_inside_range (zero, vr) == 1);
615 /* Extract value range information from an ASSERT_EXPR EXPR and store
619 extract_range_from_assert (value_range_t *vr_p, tree expr)
621 tree var, cond, limit, min, max, type;
622 value_range_t *var_vr, *limit_vr;
623 enum tree_code cond_code;
625 var = ASSERT_EXPR_VAR (expr);
626 cond = ASSERT_EXPR_COND (expr);
628 gcc_assert (COMPARISON_CLASS_P (cond));
630 /* Find VAR in the ASSERT_EXPR conditional. */
631 if (var == TREE_OPERAND (cond, 0))
633 /* If the predicate is of the form VAR COMP LIMIT, then we just
634 take LIMIT from the RHS and use the same comparison code. */
635 limit = TREE_OPERAND (cond, 1);
636 cond_code = TREE_CODE (cond);
640 /* If the predicate is of the form LIMIT COMP VAR, then we need
641 to flip around the comparison code to create the proper range
643 limit = TREE_OPERAND (cond, 0);
644 cond_code = swap_tree_comparison (TREE_CODE (cond));
647 type = TREE_TYPE (limit);
648 gcc_assert (limit != var);
650 /* For pointer arithmetic, we only keep track of pointer equality
652 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
654 set_value_range_to_varying (vr_p);
658 /* If LIMIT is another SSA name and LIMIT has a range of its own,
659 try to use LIMIT's range to avoid creating symbolic ranges
661 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
663 /* LIMIT's range is only interesting if it has any useful information. */
665 && (limit_vr->type == VR_UNDEFINED
666 || limit_vr->type == VR_VARYING
667 || symbolic_range_p (limit_vr)))
670 /* Special handling for integral types with super-types. Some FEs
671 construct integral types derived from other types and restrict
672 the range of values these new types may take.
674 It may happen that LIMIT is actually smaller than TYPE's minimum
675 value. For instance, the Ada FE is generating code like this
678 D.1480_32 = nam_30 - 300000361;
679 if (D.1480_32 <= 1) goto <L112>; else goto <L52>;
681 D.1480_94 = ASSERT_EXPR <D.1480_32, D.1480_32 <= 1>;
683 All the names are of type types__name_id___XDLU_300000000__399999999
684 which has min == 300000000 and max == 399999999. This means that
685 the ASSERT_EXPR would try to create the range [3000000, 1] which
688 The fact that the type specifies MIN and MAX values does not
689 automatically mean that every variable of that type will always
690 be within that range, so the predicate may well be true at run
691 time. If we had symbolic -INF and +INF values, we could
692 represent this range, but we currently represent -INF and +INF
693 using the type's min and max values.
695 So, the only sensible thing we can do for now is set the
696 resulting range to VR_VARYING. TODO, would having symbolic -INF
697 and +INF values be worth the trouble? */
698 if (TREE_CODE (limit) != SSA_NAME
699 && INTEGRAL_TYPE_P (type)
702 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
704 tree type_min = TYPE_MIN_VALUE (type);
705 int cmp = compare_values (limit, type_min);
707 /* For < or <= comparisons, if LIMIT is smaller than
708 TYPE_MIN, set the range to VR_VARYING. */
709 if (cmp == -1 || cmp == 0)
711 set_value_range_to_varying (vr_p);
715 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
717 tree type_max = TYPE_MIN_VALUE (type);
718 int cmp = compare_values (limit, type_max);
720 /* For > or >= comparisons, if LIMIT is bigger than
721 TYPE_MAX, set the range to VR_VARYING. */
722 if (cmp == 1 || cmp == 0)
724 set_value_range_to_varying (vr_p);
730 /* The new range has the same set of equivalences of VAR's range. */
731 gcc_assert (vr_p->equiv == NULL);
732 vr_p->equiv = BITMAP_ALLOC (NULL);
733 add_equivalence (vr_p->equiv, var);
735 /* Extract a new range based on the asserted comparison for VAR and
736 LIMIT's value range. Notice that if LIMIT has an anti-range, we
737 will only use it for equality comparisons (EQ_EXPR). For any
738 other kind of assertion, we cannot derive a range from LIMIT's
739 anti-range that can be used to describe the new range. For
740 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
741 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
742 no single range for x_2 that could describe LE_EXPR, so we might
743 as well build the range [b_4, +INF] for it. */
744 if (cond_code == EQ_EXPR)
746 enum value_range_type range_type;
750 range_type = limit_vr->type;
756 range_type = VR_RANGE;
761 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
763 /* When asserting the equality VAR == LIMIT and LIMIT is another
764 SSA name, the new range will also inherit the equivalence set
766 if (TREE_CODE (limit) == SSA_NAME)
767 add_equivalence (vr_p->equiv, limit);
769 else if (cond_code == NE_EXPR)
771 /* As described above, when LIMIT's range is an anti-range and
772 this assertion is an inequality (NE_EXPR), then we cannot
773 derive anything from the anti-range. For instance, if
774 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
775 not imply that VAR's range is [0, 0]. So, in the case of
776 anti-ranges, we just assert the inequality using LIMIT and
779 If LIMIT_VR is a range, we can only use it to build a new
780 anti-range if LIMIT_VR is a single-valued range. For
781 instance, if LIMIT_VR is [0, 1], the predicate
782 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
783 Rather, it means that for value 0 VAR should be ~[0, 0]
784 and for value 1, VAR should be ~[1, 1]. We cannot
785 represent these ranges.
787 The only situation in which we can build a valid
788 anti-range is when LIMIT_VR is a single-valued range
789 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
790 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
792 && limit_vr->type == VR_RANGE
793 && compare_values (limit_vr->min, limit_vr->max) == 0)
800 /* In any other case, we cannot use LIMIT's range to build a
805 /* If MIN and MAX cover the whole range for their type, then
806 just use the original LIMIT. */
807 if (INTEGRAL_TYPE_P (type)
808 && min == TYPE_MIN_VALUE (type)
809 && max == TYPE_MAX_VALUE (type))
812 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
814 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
816 min = TYPE_MIN_VALUE (type);
818 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
822 /* If LIMIT_VR is of the form [N1, N2], we need to build the
823 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
828 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
829 if (cond_code == LT_EXPR)
831 tree one = build_int_cst (type, 1);
832 max = fold_build2 (MINUS_EXPR, type, max, one);
835 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
837 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
839 max = TYPE_MAX_VALUE (type);
841 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
845 /* If LIMIT_VR is of the form [N1, N2], we need to build the
846 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
851 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
852 if (cond_code == GT_EXPR)
854 tree one = build_int_cst (type, 1);
855 min = fold_build2 (PLUS_EXPR, type, min, one);
858 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
863 /* If VAR already had a known range and the two ranges have a
864 non-empty intersection, we can refine the resulting range.
865 Since the assert expression creates an equivalency and at the
866 same time it asserts a predicate, we can take the intersection of
867 the two ranges to get better precision. */
868 var_vr = get_value_range (var);
869 if (var_vr->type == VR_RANGE
870 && vr_p->type == VR_RANGE
871 && value_ranges_intersect_p (var_vr, vr_p))
873 /* Use the larger of the two minimums. */
874 if (compare_values (vr_p->min, var_vr->min) == -1)
879 /* Use the smaller of the two maximums. */
880 if (compare_values (vr_p->max, var_vr->max) == 1)
885 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
890 /* Extract range information from SSA name VAR and store it in VR. If
891 VAR has an interesting range, use it. Otherwise, create the
892 range [VAR, VAR] and return it. This is useful in situations where
893 we may have conditionals testing values of VARYING names. For
900 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
904 extract_range_from_ssa_name (value_range_t *vr, tree var)
906 value_range_t *var_vr = get_value_range (var);
908 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
909 copy_value_range (vr, var_vr);
911 set_value_range (vr, VR_RANGE, var, var, NULL);
913 add_equivalence (vr->equiv, var);
917 /* Wrapper around int_const_binop. If the operation overflows and we
918 are not using wrapping arithmetic, then adjust the result to be
919 -INF or +INF depending on CODE, VAL1 and VAL2. */
922 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
927 return int_const_binop (code, val1, val2, 0);
929 /* If we are not using wrapping arithmetic, operate symbolically
931 res = int_const_binop (code, val1, val2, 0);
933 if (TYPE_UNSIGNED (TREE_TYPE (val1)))
935 int checkz = compare_values (res, val1);
937 /* Ensure that res = val1 + val2 >= val1
938 or that res = val1 - val2 <= val1. */
939 if ((code == PLUS_EXPR && !(checkz == 1 || checkz == 0))
940 || (code == MINUS_EXPR && !(checkz == 0 || checkz == -1)))
942 res = copy_node (res);
943 TREE_OVERFLOW (res) = 1;
946 /* If the operation overflowed but neither VAL1 nor VAL2 are
947 overflown, return -INF or +INF depending on the operation
948 and the combination of signs of the operands. */
949 else if (TREE_OVERFLOW (res)
950 && !TREE_OVERFLOW (val1)
951 && !TREE_OVERFLOW (val2))
953 int sgn1 = tree_int_cst_sgn (val1);
954 int sgn2 = tree_int_cst_sgn (val2);
956 /* Notice that we only need to handle the restricted set of
957 operations handled by extract_range_from_binary_expr.
958 Among them, only multiplication, addition and subtraction
959 can yield overflow without overflown operands because we
960 are working with integral types only... except in the
961 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
964 /* For multiplication, the sign of the overflow is given
965 by the comparison of the signs of the operands. */
966 if ((code == MULT_EXPR && sgn1 == sgn2)
967 /* For addition, the operands must be of the same sign
968 to yield an overflow. Its sign is therefore that
969 of one of the operands, for example the first. */
970 || (code == PLUS_EXPR && sgn1 > 0)
971 /* For subtraction, the operands must be of different
972 signs to yield an overflow. Its sign is therefore
973 that of the first operand or the opposite of that
974 of the second operand. A first operand of 0 counts
975 as positive here, for the corner case 0 - (-INF),
976 which overflows, but must yield +INF. */
977 || (code == MINUS_EXPR && sgn1 >= 0)
978 /* For division, the only case is -INF / -1 = +INF. */
979 || code == TRUNC_DIV_EXPR
980 || code == FLOOR_DIV_EXPR
981 || code == CEIL_DIV_EXPR
982 || code == EXACT_DIV_EXPR
983 || code == ROUND_DIV_EXPR)
984 return TYPE_MAX_VALUE (TREE_TYPE (res));
986 return TYPE_MIN_VALUE (TREE_TYPE (res));
993 /* Extract range information from a binary expression EXPR based on
994 the ranges of each of its operands and the expression code. */
997 extract_range_from_binary_expr (value_range_t *vr, tree expr)
999 enum tree_code code = TREE_CODE (expr);
1000 tree op0, op1, min, max;
1002 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1003 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1005 /* Not all binary expressions can be applied to ranges in a
1006 meaningful way. Handle only arithmetic operations. */
1007 if (code != PLUS_EXPR
1008 && code != MINUS_EXPR
1009 && code != MULT_EXPR
1010 && code != TRUNC_DIV_EXPR
1011 && code != FLOOR_DIV_EXPR
1012 && code != CEIL_DIV_EXPR
1013 && code != EXACT_DIV_EXPR
1014 && code != ROUND_DIV_EXPR
1017 && code != TRUTH_ANDIF_EXPR
1018 && code != TRUTH_ORIF_EXPR
1019 && code != TRUTH_AND_EXPR
1020 && code != TRUTH_OR_EXPR
1021 && code != TRUTH_XOR_EXPR)
1023 set_value_range_to_varying (vr);
1027 /* Get value ranges for each operand. For constant operands, create
1028 a new value range with the operand to simplify processing. */
1029 op0 = TREE_OPERAND (expr, 0);
1030 if (TREE_CODE (op0) == SSA_NAME)
1031 vr0 = *(get_value_range (op0));
1032 else if (is_gimple_min_invariant (op0))
1033 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1035 set_value_range_to_varying (&vr0);
1037 op1 = TREE_OPERAND (expr, 1);
1038 if (TREE_CODE (op1) == SSA_NAME)
1039 vr1 = *(get_value_range (op1));
1040 else if (is_gimple_min_invariant (op1))
1041 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1043 set_value_range_to_varying (&vr1);
1045 /* If either range is UNDEFINED, so is the result. */
1046 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1048 set_value_range_to_undefined (vr);
1052 /* Refuse to operate on VARYING ranges, ranges of different kinds
1053 and symbolic ranges. TODO, we may be able to derive anti-ranges
1055 if (vr0.type == VR_VARYING
1056 || vr1.type == VR_VARYING
1057 || vr0.type != vr1.type
1058 || symbolic_range_p (&vr0)
1059 || symbolic_range_p (&vr1))
1061 set_value_range_to_varying (vr);
1065 /* Now evaluate the expression to determine the new range. */
1066 if (POINTER_TYPE_P (TREE_TYPE (expr))
1067 || POINTER_TYPE_P (TREE_TYPE (op0))
1068 || POINTER_TYPE_P (TREE_TYPE (op1)))
1070 /* For pointer types, we are really only interested in asserting
1071 whether the expression evaluates to non-NULL. FIXME, we used
1072 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1073 ivopts is generating expressions with pointer multiplication
1075 if (code == PLUS_EXPR)
1077 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1078 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1079 else if (range_is_null (&vr0) && range_is_null (&vr1))
1080 set_value_range_to_null (vr, TREE_TYPE (expr));
1082 set_value_range_to_varying (vr);
1086 /* Subtracting from a pointer, may yield 0, so just drop the
1087 resulting range to varying. */
1088 set_value_range_to_varying (vr);
1094 /* For integer ranges, apply the operation to each end of the
1095 range and see what we end up with. */
1096 if (code == TRUTH_ANDIF_EXPR
1097 || code == TRUTH_ORIF_EXPR
1098 || code == TRUTH_AND_EXPR
1099 || code == TRUTH_OR_EXPR
1100 || code == TRUTH_XOR_EXPR)
1102 /* Boolean expressions cannot be folded with int_const_binop. */
1103 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1104 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1106 else if (code == PLUS_EXPR
1108 || code == MAX_EXPR)
1110 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1111 VR_VARYING. It would take more effort to compute a precise
1112 range for such a case. For example, if we have op0 == 1 and
1113 op1 == -1 with their ranges both being ~[0,0], we would have
1114 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1115 Note that we are guaranteed to have vr0.type == vr1.type at
1117 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1119 set_value_range_to_varying (vr);
1123 /* For operations that make the resulting range directly
1124 proportional to the original ranges, apply the operation to
1125 the same end of each range. */
1126 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1127 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1129 else if (code == MULT_EXPR
1130 || code == TRUNC_DIV_EXPR
1131 || code == FLOOR_DIV_EXPR
1132 || code == CEIL_DIV_EXPR
1133 || code == EXACT_DIV_EXPR
1134 || code == ROUND_DIV_EXPR)
1139 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1140 drop to VR_VARYING. It would take more effort to compute a
1141 precise range for such a case. For example, if we have
1142 op0 == 65536 and op1 == 65536 with their ranges both being
1143 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1144 we cannot claim that the product is in ~[0,0]. Note that we
1145 are guaranteed to have vr0.type == vr1.type at this
1147 if (code == MULT_EXPR
1148 && vr0.type == VR_ANTI_RANGE
1149 && (flag_wrapv || TYPE_UNSIGNED (TREE_TYPE (op0))))
1151 set_value_range_to_varying (vr);
1155 /* Multiplications and divisions are a bit tricky to handle,
1156 depending on the mix of signs we have in the two ranges, we
1157 need to operate on different values to get the minimum and
1158 maximum values for the new range. One approach is to figure
1159 out all the variations of range combinations and do the
1162 However, this involves several calls to compare_values and it
1163 is pretty convoluted. It's simpler to do the 4 operations
1164 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1165 MAX1) and then figure the smallest and largest values to form
1168 /* Divisions by zero result in a VARYING value. */
1169 if (code != MULT_EXPR
1170 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1172 set_value_range_to_varying (vr);
1176 /* Compute the 4 cross operations. */
1177 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1179 val[1] = (vr1.max != vr1.min)
1180 ? vrp_int_const_binop (code, vr0.min, vr1.max)
1183 val[2] = (vr0.max != vr0.min)
1184 ? vrp_int_const_binop (code, vr0.max, vr1.min)
1187 val[3] = (vr0.min != vr0.max && vr1.min != vr1.max)
1188 ? vrp_int_const_binop (code, vr0.max, vr1.max)
1191 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1195 for (i = 1; i < 4; i++)
1197 if (TREE_OVERFLOW (min) || TREE_OVERFLOW (max))
1202 if (TREE_OVERFLOW (val[i]))
1204 /* If we found an overflowed value, set MIN and MAX
1205 to it so that we set the resulting range to
1211 if (compare_values (val[i], min) == -1)
1214 if (compare_values (val[i], max) == 1)
1219 else if (code == MINUS_EXPR)
1221 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1222 VR_VARYING. It would take more effort to compute a precise
1223 range for such a case. For example, if we have op0 == 1 and
1224 op1 == 1 with their ranges both being ~[0,0], we would have
1225 op0 - op1 == 0, so we cannot claim that the difference is in
1226 ~[0,0]. Note that we are guaranteed to have
1227 vr0.type == vr1.type at this point. */
1228 if (vr0.type == VR_ANTI_RANGE)
1230 set_value_range_to_varying (vr);
1234 /* For MINUS_EXPR, apply the operation to the opposite ends of
1236 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1237 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1242 /* If either MIN or MAX overflowed, then set the resulting range to
1244 if (TREE_OVERFLOW (min) || TREE_OVERFLOW (max))
1246 set_value_range_to_varying (vr);
1250 cmp = compare_values (min, max);
1251 if (cmp == -2 || cmp == 1)
1253 /* If the new range has its limits swapped around (MIN > MAX),
1254 then the operation caused one of them to wrap around, mark
1255 the new range VARYING. */
1256 set_value_range_to_varying (vr);
1259 set_value_range (vr, vr0.type, min, max, NULL);
1263 /* Extract range information from a unary expression EXPR based on
1264 the range of its operand and the expression code. */
1267 extract_range_from_unary_expr (value_range_t *vr, tree expr)
1269 enum tree_code code = TREE_CODE (expr);
1272 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1274 /* Refuse to operate on certain unary expressions for which we
1275 cannot easily determine a resulting range. */
1276 if (code == FIX_TRUNC_EXPR
1277 || code == FIX_CEIL_EXPR
1278 || code == FIX_FLOOR_EXPR
1279 || code == FIX_ROUND_EXPR
1280 || code == FLOAT_EXPR
1281 || code == BIT_NOT_EXPR
1282 || code == NON_LVALUE_EXPR
1283 || code == CONJ_EXPR)
1285 set_value_range_to_varying (vr);
1289 /* Get value ranges for the operand. For constant operands, create
1290 a new value range with the operand to simplify processing. */
1291 op0 = TREE_OPERAND (expr, 0);
1292 if (TREE_CODE (op0) == SSA_NAME)
1293 vr0 = *(get_value_range (op0));
1294 else if (is_gimple_min_invariant (op0))
1295 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1297 set_value_range_to_varying (&vr0);
1299 /* If VR0 is UNDEFINED, so is the result. */
1300 if (vr0.type == VR_UNDEFINED)
1302 set_value_range_to_undefined (vr);
1306 /* Refuse to operate on varying and symbolic ranges. Also, if the
1307 operand is neither a pointer nor an integral type, set the
1308 resulting range to VARYING. TODO, in some cases we may be able
1309 to derive anti-ranges (like nonzero values). */
1310 if (vr0.type == VR_VARYING
1311 || (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
1312 && !POINTER_TYPE_P (TREE_TYPE (op0)))
1313 || symbolic_range_p (&vr0))
1315 set_value_range_to_varying (vr);
1319 /* If the expression involves pointers, we are only interested in
1320 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1321 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
1323 if (range_is_nonnull (&vr0) || tree_expr_nonzero_p (expr))
1324 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1325 else if (range_is_null (&vr0))
1326 set_value_range_to_null (vr, TREE_TYPE (expr));
1328 set_value_range_to_varying (vr);
1333 /* Handle unary expressions on integer ranges. */
1334 if (code == NOP_EXPR || code == CONVERT_EXPR)
1336 tree inner_type = TREE_TYPE (op0);
1337 tree outer_type = TREE_TYPE (expr);
1339 /* If VR0 represents a simple range, then try to convert
1340 the min and max values for the range to the same type
1341 as OUTER_TYPE. If the results compare equal to VR0's
1342 min and max values and the new min is still less than
1343 or equal to the new max, then we can safely use the newly
1344 computed range for EXPR. This allows us to compute
1345 accurate ranges through many casts. */
1346 if (vr0.type == VR_RANGE)
1348 tree new_min, new_max;
1350 /* Convert VR0's min/max to OUTER_TYPE. */
1351 new_min = fold_convert (outer_type, vr0.min);
1352 new_max = fold_convert (outer_type, vr0.max);
1354 /* Verify the new min/max values are gimple values and
1355 that they compare equal to VR0's min/max values. */
1356 if (is_gimple_val (new_min)
1357 && is_gimple_val (new_max)
1358 && tree_int_cst_equal (new_min, vr0.min)
1359 && tree_int_cst_equal (new_max, vr0.max)
1360 && compare_values (new_min, new_max) <= 0
1361 && compare_values (new_min, new_max) >= -1)
1363 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
1368 /* When converting types of different sizes, set the result to
1369 VARYING. Things like sign extensions and precision loss may
1370 change the range. For instance, if x_3 is of type 'long long
1371 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1372 is impossible to know at compile time whether y_5 will be
1374 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
1375 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
1377 set_value_range_to_varying (vr);
1382 /* Apply the operation to each end of the range and see what we end
1384 if (code == NEGATE_EXPR
1385 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1387 /* NEGATE_EXPR flips the range around. */
1388 min = (vr0.max == TYPE_MAX_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
1389 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1390 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1392 max = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
1393 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1394 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1396 else if (code == ABS_EXPR
1397 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1399 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1402 && ((vr0.type == VR_RANGE
1403 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1404 || (vr0.type == VR_ANTI_RANGE
1405 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
1406 && !range_includes_zero_p (&vr0))))
1408 set_value_range_to_varying (vr);
1412 /* ABS_EXPR may flip the range around, if the original range
1413 included negative values. */
1414 min = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1415 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1416 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1418 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1420 cmp = compare_values (min, max);
1422 /* If a VR_ANTI_RANGEs contains zero, then we have
1423 ~[-INF, min(MIN, MAX)]. */
1424 if (vr0.type == VR_ANTI_RANGE)
1426 if (range_includes_zero_p (&vr0))
1428 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
1430 /* Take the lower of the two values. */
1434 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1435 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1436 flag_wrapv is set and the original anti-range doesn't include
1437 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1438 min = (flag_wrapv && vr0.min != type_min_value
1439 ? int_const_binop (PLUS_EXPR,
1441 integer_one_node, 0)
1446 /* All else has failed, so create the range [0, INF], even for
1447 flag_wrapv since TYPE_MIN_VALUE is in the original
1449 vr0.type = VR_RANGE;
1450 min = build_int_cst (TREE_TYPE (expr), 0);
1451 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
1455 /* If the range contains zero then we know that the minimum value in the
1456 range will be zero. */
1457 else if (range_includes_zero_p (&vr0))
1461 min = build_int_cst (TREE_TYPE (expr), 0);
1465 /* If the range was reversed, swap MIN and MAX. */
1476 /* Otherwise, operate on each end of the range. */
1477 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1478 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1481 cmp = compare_values (min, max);
1482 if (cmp == -2 || cmp == 1)
1484 /* If the new range has its limits swapped around (MIN > MAX),
1485 then the operation caused one of them to wrap around, mark
1486 the new range VARYING. */
1487 set_value_range_to_varying (vr);
1490 set_value_range (vr, vr0.type, min, max, NULL);
1494 /* Extract range information from a comparison expression EXPR based
1495 on the range of its operand and the expression code. */
1498 extract_range_from_comparison (value_range_t *vr, tree expr)
1500 tree val = vrp_evaluate_conditional (expr, false);
1503 /* Since this expression was found on the RHS of an assignment,
1504 its type may be different from _Bool. Convert VAL to EXPR's
1506 val = fold_convert (TREE_TYPE (expr), val);
1507 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
1510 set_value_range_to_varying (vr);
1514 /* Try to compute a useful range out of expression EXPR and store it
1518 extract_range_from_expr (value_range_t *vr, tree expr)
1520 enum tree_code code = TREE_CODE (expr);
1522 if (code == ASSERT_EXPR)
1523 extract_range_from_assert (vr, expr);
1524 else if (code == SSA_NAME)
1525 extract_range_from_ssa_name (vr, expr);
1526 else if (TREE_CODE_CLASS (code) == tcc_binary
1527 || code == TRUTH_ANDIF_EXPR
1528 || code == TRUTH_ORIF_EXPR
1529 || code == TRUTH_AND_EXPR
1530 || code == TRUTH_OR_EXPR
1531 || code == TRUTH_XOR_EXPR)
1532 extract_range_from_binary_expr (vr, expr);
1533 else if (TREE_CODE_CLASS (code) == tcc_unary)
1534 extract_range_from_unary_expr (vr, expr);
1535 else if (TREE_CODE_CLASS (code) == tcc_comparison)
1536 extract_range_from_comparison (vr, expr);
1537 else if (is_gimple_min_invariant (expr))
1538 set_value_range (vr, VR_RANGE, expr, expr, NULL);
1539 else if (vrp_expr_computes_nonzero (expr))
1540 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1542 set_value_range_to_varying (vr);
1545 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1546 would be profitable to adjust VR using scalar evolution information
1547 for VAR. If so, update VR with the new limits. */
1550 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
1553 tree init, step, chrec;
1554 bool init_is_max, unknown_max;
1556 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1557 better opportunities than a regular range, but I'm not sure. */
1558 if (vr->type == VR_ANTI_RANGE)
1561 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
1562 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
1565 init = initial_condition_in_loop_num (chrec, loop->num);
1566 step = evolution_part_in_loop_num (chrec, loop->num);
1568 /* If STEP is symbolic, we can't know whether INIT will be the
1569 minimum or maximum value in the range. */
1570 if (step == NULL_TREE
1571 || !is_gimple_min_invariant (step))
1574 /* Do not adjust ranges when chrec may wrap. */
1575 if (scev_probably_wraps_p (chrec_type (chrec), init, step, stmt,
1576 cfg_loops->parray[CHREC_VARIABLE (chrec)],
1577 &init_is_max, &unknown_max)
1581 if (!POINTER_TYPE_P (TREE_TYPE (init))
1582 && (vr->type == VR_VARYING || vr->type == VR_UNDEFINED))
1584 /* For VARYING or UNDEFINED ranges, just about anything we get
1585 from scalar evolutions should be better. */
1587 set_value_range (vr, VR_RANGE, TYPE_MIN_VALUE (TREE_TYPE (init)),
1590 set_value_range (vr, VR_RANGE, init, TYPE_MAX_VALUE (TREE_TYPE (init)),
1593 else if (vr->type == VR_RANGE)
1600 /* INIT is the maximum value. If INIT is lower than VR->MAX
1601 but no smaller than VR->MIN, set VR->MAX to INIT. */
1602 if (compare_values (init, max) == -1)
1606 /* If we just created an invalid range with the minimum
1607 greater than the maximum, take the minimum all the
1609 if (compare_values (min, max) == 1)
1610 min = TYPE_MIN_VALUE (TREE_TYPE (min));
1615 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
1616 if (compare_values (init, min) == 1)
1620 /* If we just created an invalid range with the minimum
1621 greater than the maximum, take the maximum all the
1623 if (compare_values (min, max) == 1)
1624 max = TYPE_MAX_VALUE (TREE_TYPE (max));
1628 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
1633 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
1635 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
1636 all the values in the ranges.
1638 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
1640 - Return NULL_TREE if it is not always possible to determine the
1641 value of the comparison. */
1645 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1)
1647 /* VARYING or UNDEFINED ranges cannot be compared. */
1648 if (vr0->type == VR_VARYING
1649 || vr0->type == VR_UNDEFINED
1650 || vr1->type == VR_VARYING
1651 || vr1->type == VR_UNDEFINED)
1654 /* Anti-ranges need to be handled separately. */
1655 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
1657 /* If both are anti-ranges, then we cannot compute any
1659 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
1662 /* These comparisons are never statically computable. */
1669 /* Equality can be computed only between a range and an
1670 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
1671 if (vr0->type == VR_RANGE)
1673 /* To simplify processing, make VR0 the anti-range. */
1674 value_range_t *tmp = vr0;
1679 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
1681 if (compare_values (vr0->min, vr1->min) == 0
1682 && compare_values (vr0->max, vr1->max) == 0)
1683 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
1688 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
1689 operands around and change the comparison code. */
1690 if (comp == GT_EXPR || comp == GE_EXPR)
1693 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
1699 if (comp == EQ_EXPR)
1701 /* Equality may only be computed if both ranges represent
1702 exactly one value. */
1703 if (compare_values (vr0->min, vr0->max) == 0
1704 && compare_values (vr1->min, vr1->max) == 0)
1706 int cmp_min = compare_values (vr0->min, vr1->min);
1707 int cmp_max = compare_values (vr0->max, vr1->max);
1708 if (cmp_min == 0 && cmp_max == 0)
1709 return boolean_true_node;
1710 else if (cmp_min != -2 && cmp_max != -2)
1711 return boolean_false_node;
1716 else if (comp == NE_EXPR)
1720 /* If VR0 is completely to the left or completely to the right
1721 of VR1, they are always different. Notice that we need to
1722 make sure that both comparisons yield similar results to
1723 avoid comparing values that cannot be compared at
1725 cmp1 = compare_values (vr0->max, vr1->min);
1726 cmp2 = compare_values (vr0->min, vr1->max);
1727 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
1728 return boolean_true_node;
1730 /* If VR0 and VR1 represent a single value and are identical,
1732 else if (compare_values (vr0->min, vr0->max) == 0
1733 && compare_values (vr1->min, vr1->max) == 0
1734 && compare_values (vr0->min, vr1->min) == 0
1735 && compare_values (vr0->max, vr1->max) == 0)
1736 return boolean_false_node;
1738 /* Otherwise, they may or may not be different. */
1742 else if (comp == LT_EXPR || comp == LE_EXPR)
1746 /* If VR0 is to the left of VR1, return true. */
1747 tst = compare_values (vr0->max, vr1->min);
1748 if ((comp == LT_EXPR && tst == -1)
1749 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
1750 return boolean_true_node;
1752 /* If VR0 is to the right of VR1, return false. */
1753 tst = compare_values (vr0->min, vr1->max);
1754 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
1755 || (comp == LE_EXPR && tst == 1))
1756 return boolean_false_node;
1758 /* Otherwise, we don't know. */
1766 /* Given a value range VR, a value VAL and a comparison code COMP, return
1767 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
1768 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
1769 always returns false. Return NULL_TREE if it is not always
1770 possible to determine the value of the comparison. */
1773 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val)
1775 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
1778 /* Anti-ranges need to be handled separately. */
1779 if (vr->type == VR_ANTI_RANGE)
1781 /* For anti-ranges, the only predicates that we can compute at
1782 compile time are equality and inequality. */
1789 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
1790 if (value_inside_range (val, vr) == 1)
1791 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
1796 if (comp == EQ_EXPR)
1798 /* EQ_EXPR may only be computed if VR represents exactly
1800 if (compare_values (vr->min, vr->max) == 0)
1802 int cmp = compare_values (vr->min, val);
1804 return boolean_true_node;
1805 else if (cmp == -1 || cmp == 1 || cmp == 2)
1806 return boolean_false_node;
1808 else if (compare_values (val, vr->min) == -1
1809 || compare_values (vr->max, val) == -1)
1810 return boolean_false_node;
1814 else if (comp == NE_EXPR)
1816 /* If VAL is not inside VR, then they are always different. */
1817 if (compare_values (vr->max, val) == -1
1818 || compare_values (vr->min, val) == 1)
1819 return boolean_true_node;
1821 /* If VR represents exactly one value equal to VAL, then return
1823 if (compare_values (vr->min, vr->max) == 0
1824 && compare_values (vr->min, val) == 0)
1825 return boolean_false_node;
1827 /* Otherwise, they may or may not be different. */
1830 else if (comp == LT_EXPR || comp == LE_EXPR)
1834 /* If VR is to the left of VAL, return true. */
1835 tst = compare_values (vr->max, val);
1836 if ((comp == LT_EXPR && tst == -1)
1837 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
1838 return boolean_true_node;
1840 /* If VR is to the right of VAL, return false. */
1841 tst = compare_values (vr->min, val);
1842 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
1843 || (comp == LE_EXPR && tst == 1))
1844 return boolean_false_node;
1846 /* Otherwise, we don't know. */
1849 else if (comp == GT_EXPR || comp == GE_EXPR)
1853 /* If VR is to the right of VAL, return true. */
1854 tst = compare_values (vr->min, val);
1855 if ((comp == GT_EXPR && tst == 1)
1856 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
1857 return boolean_true_node;
1859 /* If VR is to the left of VAL, return false. */
1860 tst = compare_values (vr->max, val);
1861 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
1862 || (comp == GE_EXPR && tst == -1))
1863 return boolean_false_node;
1865 /* Otherwise, we don't know. */
1873 /* Debugging dumps. */
1875 void dump_value_range (FILE *, value_range_t *);
1876 void debug_value_range (value_range_t *);
1877 void dump_all_value_ranges (FILE *);
1878 void debug_all_value_ranges (void);
1879 void dump_vr_equiv (FILE *, bitmap);
1880 void debug_vr_equiv (bitmap);
1883 /* Dump value range VR to FILE. */
1886 dump_value_range (FILE *file, value_range_t *vr)
1889 fprintf (file, "[]");
1890 else if (vr->type == VR_UNDEFINED)
1891 fprintf (file, "UNDEFINED");
1892 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
1894 tree type = TREE_TYPE (vr->min);
1896 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
1898 if (INTEGRAL_TYPE_P (type)
1899 && !TYPE_UNSIGNED (type)
1900 && vr->min == TYPE_MIN_VALUE (type))
1901 fprintf (file, "-INF");
1903 print_generic_expr (file, vr->min, 0);
1905 fprintf (file, ", ");
1907 if (INTEGRAL_TYPE_P (type)
1908 && vr->max == TYPE_MAX_VALUE (type))
1909 fprintf (file, "+INF");
1911 print_generic_expr (file, vr->max, 0);
1913 fprintf (file, "]");
1920 fprintf (file, " EQUIVALENCES: { ");
1922 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
1924 print_generic_expr (file, ssa_name (i), 0);
1925 fprintf (file, " ");
1929 fprintf (file, "} (%u elements)", c);
1932 else if (vr->type == VR_VARYING)
1933 fprintf (file, "VARYING");
1935 fprintf (file, "INVALID RANGE");
1939 /* Dump value range VR to stderr. */
1942 debug_value_range (value_range_t *vr)
1944 dump_value_range (stderr, vr);
1948 /* Dump value ranges of all SSA_NAMEs to FILE. */
1951 dump_all_value_ranges (FILE *file)
1955 for (i = 0; i < num_ssa_names; i++)
1959 print_generic_expr (file, ssa_name (i), 0);
1960 fprintf (file, ": ");
1961 dump_value_range (file, vr_value[i]);
1962 fprintf (file, "\n");
1966 fprintf (file, "\n");
1970 /* Dump all value ranges to stderr. */
1973 debug_all_value_ranges (void)
1975 dump_all_value_ranges (stderr);
1979 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
1980 create a new SSA name N and return the assertion assignment
1981 'V = ASSERT_EXPR <V, V OP W>'. */
1984 build_assert_expr_for (tree cond, tree v)
1988 gcc_assert (TREE_CODE (v) == SSA_NAME);
1989 n = duplicate_ssa_name (v, NULL_TREE);
1991 if (COMPARISON_CLASS_P (cond))
1993 tree a = build (ASSERT_EXPR, TREE_TYPE (v), v, cond);
1994 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, a);
1996 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
1998 /* Given !V, build the assignment N = false. */
1999 tree op0 = TREE_OPERAND (cond, 0);
2000 gcc_assert (op0 == v);
2001 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, boolean_false_node);
2003 else if (TREE_CODE (cond) == SSA_NAME)
2005 /* Given V, build the assignment N = true. */
2006 gcc_assert (v == cond);
2007 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, boolean_true_node);
2012 SSA_NAME_DEF_STMT (n) = assertion;
2014 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
2015 operand of the ASSERT_EXPR. Register the new name and the old one
2016 in the replacement table so that we can fix the SSA web after
2017 adding all the ASSERT_EXPRs. */
2018 register_new_name_mapping (n, v);
2024 /* Return false if EXPR is a predicate expression involving floating
2028 fp_predicate (tree expr)
2030 return (COMPARISON_CLASS_P (expr)
2031 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
2035 /* If the range of values taken by OP can be inferred after STMT executes,
2036 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2037 describes the inferred range. Return true if a range could be
2041 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
2044 *comp_code_p = ERROR_MARK;
2046 /* Do not attempt to infer anything in names that flow through
2048 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
2051 /* Similarly, don't infer anything from statements that may throw
2053 if (tree_could_throw_p (stmt))
2056 if (POINTER_TYPE_P (TREE_TYPE (op)))
2059 unsigned num_uses, num_derefs;
2061 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
2062 if (num_derefs > 0 && flag_delete_null_pointer_checks)
2064 /* We can only assume that a pointer dereference will yield
2065 non-NULL if -fdelete-null-pointer-checks is enabled. */
2066 *val_p = build_int_cst (TREE_TYPE (op), 0);
2067 *comp_code_p = NE_EXPR;
2076 void dump_asserts_for (FILE *, tree);
2077 void debug_asserts_for (tree);
2078 void dump_all_asserts (FILE *);
2079 void debug_all_asserts (void);
2081 /* Dump all the registered assertions for NAME to FILE. */
2084 dump_asserts_for (FILE *file, tree name)
2088 fprintf (file, "Assertions to be inserted for ");
2089 print_generic_expr (file, name, 0);
2090 fprintf (file, "\n");
2092 loc = asserts_for[SSA_NAME_VERSION (name)];
2095 fprintf (file, "\t");
2096 print_generic_expr (file, bsi_stmt (loc->si), 0);
2097 fprintf (file, "\n\tBB #%d", loc->bb->index);
2100 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
2101 loc->e->dest->index);
2102 dump_edge_info (file, loc->e, 0);
2104 fprintf (file, "\n\tPREDICATE: ");
2105 print_generic_expr (file, name, 0);
2106 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
2107 print_generic_expr (file, loc->val, 0);
2108 fprintf (file, "\n\n");
2112 fprintf (file, "\n");
2116 /* Dump all the registered assertions for NAME to stderr. */
2119 debug_asserts_for (tree name)
2121 dump_asserts_for (stderr, name);
2125 /* Dump all the registered assertions for all the names to FILE. */
2128 dump_all_asserts (FILE *file)
2133 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
2134 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2135 dump_asserts_for (file, ssa_name (i));
2136 fprintf (file, "\n");
2140 /* Dump all the registered assertions for all the names to stderr. */
2143 debug_all_asserts (void)
2145 dump_all_asserts (stderr);
2149 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2150 'NAME COMP_CODE VAL' at a location that dominates block BB or
2151 E->DEST, then register this location as a possible insertion point
2152 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2154 BB, E and SI provide the exact insertion point for the new
2155 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2156 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2157 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2158 must not be NULL. */
2161 register_new_assert_for (tree name,
2162 enum tree_code comp_code,
2166 block_stmt_iterator si)
2168 assert_locus_t n, loc, last_loc;
2170 basic_block dest_bb;
2172 #if defined ENABLE_CHECKING
2173 gcc_assert (bb == NULL || e == NULL);
2176 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
2177 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
2180 /* The new assertion A will be inserted at BB or E. We need to
2181 determine if the new location is dominated by a previously
2182 registered location for A. If we are doing an edge insertion,
2183 assume that A will be inserted at E->DEST. Note that this is not
2186 If E is a critical edge, it will be split. But even if E is
2187 split, the new block will dominate the same set of blocks that
2190 The reverse, however, is not true, blocks dominated by E->DEST
2191 will not be dominated by the new block created to split E. So,
2192 if the insertion location is on a critical edge, we will not use
2193 the new location to move another assertion previously registered
2194 at a block dominated by E->DEST. */
2195 dest_bb = (bb) ? bb : e->dest;
2197 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2198 VAL at a block dominating DEST_BB, then we don't need to insert a new
2199 one. Similarly, if the same assertion already exists at a block
2200 dominated by DEST_BB and the new location is not on a critical
2201 edge, then update the existing location for the assertion (i.e.,
2202 move the assertion up in the dominance tree).
2204 Note, this is implemented as a simple linked list because there
2205 should not be more than a handful of assertions registered per
2206 name. If this becomes a performance problem, a table hashed by
2207 COMP_CODE and VAL could be implemented. */
2208 loc = asserts_for[SSA_NAME_VERSION (name)];
2213 if (loc->comp_code == comp_code
2215 || operand_equal_p (loc->val, val, 0)))
2217 /* If the assertion NAME COMP_CODE VAL has already been
2218 registered at a basic block that dominates DEST_BB, then
2219 we don't need to insert the same assertion again. Note
2220 that we don't check strict dominance here to avoid
2221 replicating the same assertion inside the same basic
2222 block more than once (e.g., when a pointer is
2223 dereferenced several times inside a block).
2225 An exception to this rule are edge insertions. If the
2226 new assertion is to be inserted on edge E, then it will
2227 dominate all the other insertions that we may want to
2228 insert in DEST_BB. So, if we are doing an edge
2229 insertion, don't do this dominance check. */
2231 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
2234 /* Otherwise, if E is not a critical edge and DEST_BB
2235 dominates the existing location for the assertion, move
2236 the assertion up in the dominance tree by updating its
2237 location information. */
2238 if ((e == NULL || !EDGE_CRITICAL_P (e))
2239 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
2248 /* Update the last node of the list and move to the next one. */
2253 /* If we didn't find an assertion already registered for
2254 NAME COMP_CODE VAL, add a new one at the end of the list of
2255 assertions associated with NAME. */
2256 n = xmalloc (sizeof (*n));
2260 n->comp_code = comp_code;
2267 asserts_for[SSA_NAME_VERSION (name)] = n;
2269 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
2273 /* Try to register an edge assertion for SSA name NAME on edge E for
2274 the conditional jump pointed to by SI. Return true if an assertion
2275 for NAME could be registered. */
2278 register_edge_assert_for (tree name, edge e, block_stmt_iterator si)
2281 enum tree_code comp_code;
2283 stmt = bsi_stmt (si);
2285 /* Do not attempt to infer anything in names that flow through
2287 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
2290 /* If NAME was not found in the sub-graph reachable from E, then
2291 there's nothing to do. */
2292 if (!TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
2295 /* We found a use of NAME in the sub-graph rooted at E->DEST.
2296 Register an assertion for NAME according to the value that NAME
2298 if (TREE_CODE (stmt) == COND_EXPR)
2300 /* If BB ends in a COND_EXPR then NAME then we should insert
2301 the original predicate on EDGE_TRUE_VALUE and the
2302 opposite predicate on EDGE_FALSE_VALUE. */
2303 tree cond = COND_EXPR_COND (stmt);
2304 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
2306 /* Predicates may be a single SSA name or NAME OP VAL. */
2309 /* If the predicate is a name, it must be NAME, in which
2310 case we create the predicate NAME == true or
2311 NAME == false accordingly. */
2312 comp_code = EQ_EXPR;
2313 val = (is_else_edge) ? boolean_false_node : boolean_true_node;
2317 /* Otherwise, we have a comparison of the form NAME COMP VAL
2318 or VAL COMP NAME. */
2319 if (name == TREE_OPERAND (cond, 1))
2321 /* If the predicate is of the form VAL COMP NAME, flip
2322 COMP around because we need to register NAME as the
2323 first operand in the predicate. */
2324 comp_code = swap_tree_comparison (TREE_CODE (cond));
2325 val = TREE_OPERAND (cond, 0);
2329 /* The comparison is of the form NAME COMP VAL, so the
2330 comparison code remains unchanged. */
2331 comp_code = TREE_CODE (cond);
2332 val = TREE_OPERAND (cond, 1);
2335 /* If we are inserting the assertion on the ELSE edge, we
2336 need to invert the sign comparison. */
2338 comp_code = invert_tree_comparison (comp_code, 0);
2343 /* FIXME. Handle SWITCH_EXPR. */
2347 register_new_assert_for (name, comp_code, val, NULL, e, si);
2352 static bool find_assert_locations (basic_block bb);
2354 /* Determine whether the outgoing edges of BB should receive an
2355 ASSERT_EXPR for each of the operands of BB's last statement. The
2356 last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2358 If any of the sub-graphs rooted at BB have an interesting use of
2359 the predicate operands, an assert location node is added to the
2360 list of assertions for the corresponding operands. */
2363 find_conditional_asserts (basic_block bb)
2366 block_stmt_iterator last_si;
2372 need_assert = false;
2373 last_si = bsi_last (bb);
2374 last = bsi_stmt (last_si);
2376 /* Look for uses of the operands in each of the sub-graphs
2377 rooted at BB. We need to check each of the outgoing edges
2378 separately, so that we know what kind of ASSERT_EXPR to
2380 FOR_EACH_EDGE (e, ei, bb->succs)
2385 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
2386 Otherwise, when we finish traversing each of the sub-graphs, we
2387 won't know whether the variables were found in the sub-graphs or
2388 if they had been found in a block upstream from BB. */
2389 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2390 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2392 /* Traverse the strictly dominated sub-graph rooted at E->DEST
2393 to determine if any of the operands in the conditional
2394 predicate are used. */
2396 need_assert |= find_assert_locations (e->dest);
2398 /* Register the necessary assertions for each operand in the
2399 conditional predicate. */
2400 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2401 need_assert |= register_edge_assert_for (op, e, last_si);
2404 /* Finally, indicate that we have found the operands in the
2406 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2407 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2413 /* Traverse all the statements in block BB looking for statements that
2414 may generate useful assertions for the SSA names in their operand.
2415 If a statement produces a useful assertion A for name N_i, then the
2416 list of assertions already generated for N_i is scanned to
2417 determine if A is actually needed.
2419 If N_i already had the assertion A at a location dominating the
2420 current location, then nothing needs to be done. Otherwise, the
2421 new location for A is recorded instead.
2423 1- For every statement S in BB, all the variables used by S are
2424 added to bitmap FOUND_IN_SUBGRAPH.
2426 2- If statement S uses an operand N in a way that exposes a known
2427 value range for N, then if N was not already generated by an
2428 ASSERT_EXPR, create a new assert location for N. For instance,
2429 if N is a pointer and the statement dereferences it, we can
2430 assume that N is not NULL.
2432 3- COND_EXPRs are a special case of #2. We can derive range
2433 information from the predicate but need to insert different
2434 ASSERT_EXPRs for each of the sub-graphs rooted at the
2435 conditional block. If the last statement of BB is a conditional
2436 expression of the form 'X op Y', then
2438 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
2440 b) If the conditional is the only entry point to the sub-graph
2441 corresponding to the THEN_CLAUSE, recurse into it. On
2442 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
2443 an ASSERT_EXPR is added for the corresponding variable.
2445 c) Repeat step (b) on the ELSE_CLAUSE.
2447 d) Mark X and Y in FOUND_IN_SUBGRAPH.
2456 In this case, an assertion on the THEN clause is useful to
2457 determine that 'a' is always 9 on that edge. However, an assertion
2458 on the ELSE clause would be unnecessary.
2460 4- If BB does not end in a conditional expression, then we recurse
2461 into BB's dominator children.
2463 At the end of the recursive traversal, every SSA name will have a
2464 list of locations where ASSERT_EXPRs should be added. When a new
2465 location for name N is found, it is registered by calling
2466 register_new_assert_for. That function keeps track of all the
2467 registered assertions to prevent adding unnecessary assertions.
2468 For instance, if a pointer P_4 is dereferenced more than once in a
2469 dominator tree, only the location dominating all the dereference of
2470 P_4 will receive an ASSERT_EXPR.
2472 If this function returns true, then it means that there are names
2473 for which we need to generate ASSERT_EXPRs. Those assertions are
2474 inserted by process_assert_insertions.
2476 TODO. Handle SWITCH_EXPR. */
2479 find_assert_locations (basic_block bb)
2481 block_stmt_iterator si;
2486 if (TEST_BIT (blocks_visited, bb->index))
2489 SET_BIT (blocks_visited, bb->index);
2491 need_assert = false;
2493 /* Traverse all PHI nodes in BB marking used operands. */
2494 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
2496 use_operand_p arg_p;
2499 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
2501 tree arg = USE_FROM_PTR (arg_p);
2502 if (TREE_CODE (arg) == SSA_NAME)
2504 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
2505 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
2510 /* Traverse all the statements in BB marking used names and looking
2511 for statements that may infer assertions for their used operands. */
2513 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
2518 stmt = bsi_stmt (si);
2520 /* See if we can derive an assertion for any of STMT's operands. */
2521 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
2524 enum tree_code comp_code;
2526 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
2527 the sub-graph of a conditional block, when we return from
2528 this recursive walk, our parent will use the
2529 FOUND_IN_SUBGRAPH bitset to determine if one of the
2530 operands it was looking for was present in the sub-graph. */
2531 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2533 /* If OP is used only once, namely in this STMT, don't
2534 bother creating an ASSERT_EXPR for it. Such an
2535 ASSERT_EXPR would do nothing but increase compile time.
2536 Experiments show that with this simple check, we can save
2537 more than 20% of ASSERT_EXPRs. */
2538 if (has_single_use (op))
2541 /* If OP is used in such a way that we can infer a value
2542 range for it, and we don't find a previous assertion for
2543 it, create a new assertion location node for OP. */
2544 if (infer_value_range (stmt, op, &comp_code, &value))
2546 register_new_assert_for (op, comp_code, value, bb, NULL, si);
2551 /* Remember the last statement of the block. */
2555 /* If BB's last statement is a conditional expression
2556 involving integer operands, recurse into each of the sub-graphs
2557 rooted at BB to determine if we need to add ASSERT_EXPRs. */
2559 && TREE_CODE (last) == COND_EXPR
2560 && !fp_predicate (COND_EXPR_COND (last))
2561 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
2562 need_assert |= find_conditional_asserts (bb);
2564 /* Recurse into the dominator children of BB. */
2565 for (son = first_dom_son (CDI_DOMINATORS, bb);
2567 son = next_dom_son (CDI_DOMINATORS, son))
2568 need_assert |= find_assert_locations (son);
2574 /* Create an ASSERT_EXPR for NAME and insert it in the location
2575 indicated by LOC. Return true if we made any edge insertions. */
2578 process_assert_insertions_for (tree name, assert_locus_t loc)
2580 /* Build the comparison expression NAME_i COMP_CODE VAL. */
2581 tree stmt, cond, assert_expr;
2585 cond = build (loc->comp_code, boolean_type_node, name, loc->val);
2586 assert_expr = build_assert_expr_for (cond, name);
2590 /* We have been asked to insert the assertion on an edge. This
2591 is used only by COND_EXPR and SWITCH_EXPR assertions. */
2592 #if defined ENABLE_CHECKING
2593 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
2594 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
2597 bsi_insert_on_edge (loc->e, assert_expr);
2601 /* Otherwise, we can insert right after LOC->SI iff the
2602 statement must not be the last statement in the block. */
2603 stmt = bsi_stmt (loc->si);
2604 if (!stmt_ends_bb_p (stmt))
2606 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
2610 /* If STMT must be the last statement in BB, we can only insert new
2611 assertions on the non-abnormal edge out of BB. Note that since
2612 STMT is not control flow, there may only be one non-abnormal edge
2614 FOR_EACH_EDGE (e, ei, loc->bb->succs)
2615 if (!(e->flags & EDGE_ABNORMAL))
2617 bsi_insert_on_edge (e, assert_expr);
2625 /* Process all the insertions registered for every name N_i registered
2626 in NEED_ASSERT_FOR. The list of assertions to be inserted are
2627 found in ASSERTS_FOR[i]. */
2630 process_assert_insertions (void)
2634 bool update_edges_p = false;
2635 int num_asserts = 0;
2637 if (dump_file && (dump_flags & TDF_DETAILS))
2638 dump_all_asserts (dump_file);
2640 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2642 assert_locus_t loc = asserts_for[i];
2647 assert_locus_t next = loc->next;
2648 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
2656 bsi_commit_edge_inserts ();
2658 if (dump_file && (dump_flags & TDF_STATS))
2659 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
2664 /* Traverse the flowgraph looking for conditional jumps to insert range
2665 expressions. These range expressions are meant to provide information
2666 to optimizations that need to reason in terms of value ranges. They
2667 will not be expanded into RTL. For instance, given:
2676 this pass will transform the code into:
2682 x = ASSERT_EXPR <x, x < y>
2687 y = ASSERT_EXPR <y, x <= y>
2691 The idea is that once copy and constant propagation have run, other
2692 optimizations will be able to determine what ranges of values can 'x'
2693 take in different paths of the code, simply by checking the reaching
2694 definition of 'x'. */
2697 insert_range_assertions (void)
2703 found_in_subgraph = sbitmap_alloc (num_ssa_names);
2704 sbitmap_zero (found_in_subgraph);
2706 blocks_visited = sbitmap_alloc (last_basic_block);
2707 sbitmap_zero (blocks_visited);
2709 need_assert_for = BITMAP_ALLOC (NULL);
2710 asserts_for = xmalloc (num_ssa_names * sizeof (assert_locus_t));
2711 memset (asserts_for, 0, num_ssa_names * sizeof (assert_locus_t));
2713 calculate_dominance_info (CDI_DOMINATORS);
2715 update_ssa_p = false;
2716 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2717 if (find_assert_locations (e->dest))
2718 update_ssa_p = true;
2722 process_assert_insertions ();
2723 update_ssa (TODO_update_ssa_no_phi);
2726 if (dump_file && (dump_flags & TDF_DETAILS))
2728 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
2729 dump_function_to_file (current_function_decl, dump_file, dump_flags);
2732 sbitmap_free (found_in_subgraph);
2734 BITMAP_FREE (need_assert_for);
2738 /* Convert range assertion expressions into the implied copies and
2739 copy propagate away the copies. Doing the trivial copy propagation
2740 here avoids the need to run the full copy propagation pass after
2743 FIXME, this will eventually lead to copy propagation removing the
2744 names that had useful range information attached to them. For
2745 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
2746 then N_i will have the range [3, +INF].
2748 However, by converting the assertion into the implied copy
2749 operation N_i = N_j, we will then copy-propagate N_j into the uses
2750 of N_i and lose the range information. We may want to hold on to
2751 ASSERT_EXPRs a little while longer as the ranges could be used in
2752 things like jump threading.
2754 The problem with keeping ASSERT_EXPRs around is that passes after
2755 VRP need to handle them appropriately.
2757 Another approach would be to make the range information a first
2758 class property of the SSA_NAME so that it can be queried from
2759 any pass. This is made somewhat more complex by the need for
2760 multiple ranges to be associated with one SSA_NAME. */
2763 remove_range_assertions (void)
2766 block_stmt_iterator si;
2768 /* Note that the BSI iterator bump happens at the bottom of the
2769 loop and no bump is necessary if we're removing the statement
2770 referenced by the current BSI. */
2772 for (si = bsi_start (bb); !bsi_end_p (si);)
2774 tree stmt = bsi_stmt (si);
2776 if (TREE_CODE (stmt) == MODIFY_EXPR
2777 && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
2779 tree rhs = TREE_OPERAND (stmt, 1);
2780 tree cond = fold (ASSERT_EXPR_COND (rhs));
2781 use_operand_p use_p;
2782 imm_use_iterator iter;
2784 gcc_assert (cond != boolean_false_node);
2785 TREE_OPERAND (stmt, 1) = ASSERT_EXPR_VAR (rhs);
2788 /* The statement is now a copy. Propagate the RHS into
2789 every use of the LHS. */
2790 FOR_EACH_IMM_USE_SAFE (use_p, iter, TREE_OPERAND (stmt, 0))
2792 SET_USE (use_p, ASSERT_EXPR_VAR (rhs));
2793 update_stmt (USE_STMT (use_p));
2796 /* And finally, remove the copy, it is not needed. */
2803 sbitmap_free (blocks_visited);
2807 /* Return true if STMT is interesting for VRP. */
2810 stmt_interesting_for_vrp (tree stmt)
2812 if (TREE_CODE (stmt) == PHI_NODE
2813 && is_gimple_reg (PHI_RESULT (stmt))
2814 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
2815 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
2817 else if (TREE_CODE (stmt) == MODIFY_EXPR)
2819 tree lhs = TREE_OPERAND (stmt, 0);
2821 if (TREE_CODE (lhs) == SSA_NAME
2822 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
2823 || POINTER_TYPE_P (TREE_TYPE (lhs)))
2824 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
2827 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
2834 /* Initialize local data structures for VRP. */
2837 vrp_initialize (void)
2841 vr_value = xmalloc (num_ssa_names * sizeof (value_range_t *));
2842 memset (vr_value, 0, num_ssa_names * sizeof (value_range_t *));
2846 block_stmt_iterator si;
2849 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
2851 if (!stmt_interesting_for_vrp (phi))
2853 tree lhs = PHI_RESULT (phi);
2854 set_value_range_to_varying (get_value_range (lhs));
2855 DONT_SIMULATE_AGAIN (phi) = true;
2858 DONT_SIMULATE_AGAIN (phi) = false;
2861 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
2863 tree stmt = bsi_stmt (si);
2865 if (!stmt_interesting_for_vrp (stmt))
2869 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
2870 set_value_range_to_varying (get_value_range (def));
2871 DONT_SIMULATE_AGAIN (stmt) = true;
2875 DONT_SIMULATE_AGAIN (stmt) = false;
2882 /* Visit assignment STMT. If it produces an interesting range, record
2883 the SSA name in *OUTPUT_P. */
2885 static enum ssa_prop_result
2886 vrp_visit_assignment (tree stmt, tree *output_p)
2891 lhs = TREE_OPERAND (stmt, 0);
2892 rhs = TREE_OPERAND (stmt, 1);
2894 /* We only keep track of ranges in integral and pointer types. */
2895 if (TREE_CODE (lhs) == SSA_NAME
2896 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
2897 || POINTER_TYPE_P (TREE_TYPE (lhs))))
2900 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2902 extract_range_from_expr (&new_vr, rhs);
2904 /* If STMT is inside a loop, we may be able to know something
2905 else about the range of LHS by examining scalar evolution
2907 if (cfg_loops && (l = loop_containing_stmt (stmt)))
2908 adjust_range_with_scev (&new_vr, l, stmt, lhs);
2910 if (update_value_range (lhs, &new_vr))
2914 if (dump_file && (dump_flags & TDF_DETAILS))
2916 fprintf (dump_file, "Found new range for ");
2917 print_generic_expr (dump_file, lhs, 0);
2918 fprintf (dump_file, ": ");
2919 dump_value_range (dump_file, &new_vr);
2920 fprintf (dump_file, "\n\n");
2923 if (new_vr.type == VR_VARYING)
2924 return SSA_PROP_VARYING;
2926 return SSA_PROP_INTERESTING;
2929 return SSA_PROP_NOT_INTERESTING;
2932 /* Every other statement produces no useful ranges. */
2933 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
2934 set_value_range_to_varying (get_value_range (def));
2936 return SSA_PROP_VARYING;
2940 /* Compare all the value ranges for names equivalent to VAR with VAL
2941 using comparison code COMP. Return the same value returned by
2942 compare_range_with_value. */
2945 compare_name_with_value (enum tree_code comp, tree var, tree val)
2952 t = retval = NULL_TREE;
2954 /* Get the set of equivalences for VAR. */
2955 e = get_value_range (var)->equiv;
2957 /* Add VAR to its own set of equivalences so that VAR's value range
2958 is processed by this loop (otherwise, we would have to replicate
2959 the body of the loop just to check VAR's value range). */
2960 bitmap_set_bit (e, SSA_NAME_VERSION (var));
2962 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
2964 value_range_t equiv_vr = *(vr_value[i]);
2966 /* If name N_i does not have a valid range, use N_i as its own
2967 range. This allows us to compare against names that may
2968 have N_i in their ranges. */
2969 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
2971 equiv_vr.type = VR_RANGE;
2972 equiv_vr.min = ssa_name (i);
2973 equiv_vr.max = ssa_name (i);
2976 t = compare_range_with_value (comp, &equiv_vr, val);
2979 /* All the ranges should compare the same against VAL. */
2980 gcc_assert (retval == NULL || t == retval);
2985 /* Remove VAR from its own equivalence set. */
2986 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
2991 /* We couldn't find a non-NULL value for the predicate. */
2996 /* Given a comparison code COMP and names N1 and N2, compare all the
2997 ranges equivalent to N1 against all the ranges equivalent to N2
2998 to determine the value of N1 COMP N2. Return the same value
2999 returned by compare_ranges. */
3002 compare_names (enum tree_code comp, tree n1, tree n2)
3006 bitmap_iterator bi1, bi2;
3009 /* Compare the ranges of every name equivalent to N1 against the
3010 ranges of every name equivalent to N2. */
3011 e1 = get_value_range (n1)->equiv;
3012 e2 = get_value_range (n2)->equiv;
3014 /* Add N1 and N2 to their own set of equivalences to avoid
3015 duplicating the body of the loop just to check N1 and N2
3017 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
3018 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
3020 /* If the equivalence sets have a common intersection, then the two
3021 names can be compared without checking their ranges. */
3022 if (bitmap_intersect_p (e1, e2))
3024 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3025 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3027 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
3029 : boolean_false_node;
3032 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3033 N2 to their own set of equivalences to avoid duplicating the body
3034 of the loop just to check N1 and N2 ranges. */
3035 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
3037 value_range_t vr1 = *(vr_value[i1]);
3039 /* If the range is VARYING or UNDEFINED, use the name itself. */
3040 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
3042 vr1.type = VR_RANGE;
3043 vr1.min = ssa_name (i1);
3044 vr1.max = ssa_name (i1);
3047 t = retval = NULL_TREE;
3048 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
3050 value_range_t vr2 = *(vr_value[i2]);
3052 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
3054 vr2.type = VR_RANGE;
3055 vr2.min = ssa_name (i2);
3056 vr2.max = ssa_name (i2);
3059 t = compare_ranges (comp, &vr1, &vr2);
3062 /* All the ranges in the equivalent sets should compare
3064 gcc_assert (retval == NULL || t == retval);
3071 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3072 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3077 /* None of the equivalent ranges are useful in computing this
3079 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3080 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3085 /* Given a conditional predicate COND, try to determine if COND yields
3086 true or false based on the value ranges of its operands. Return
3087 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3088 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3089 NULL if the conditional cannot be evaluated at compile time.
3091 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3092 the operands in COND are used when trying to compute its value.
3093 This is only used during final substitution. During propagation,
3094 we only check the range of each variable and not its equivalents. */
3097 vrp_evaluate_conditional (tree cond, bool use_equiv_p)
3099 gcc_assert (TREE_CODE (cond) == SSA_NAME
3100 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
3102 if (TREE_CODE (cond) == SSA_NAME)
3108 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node);
3111 value_range_t *vr = get_value_range (cond);
3112 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node);
3115 /* If COND has a known boolean range, return it. */
3119 /* Otherwise, if COND has a symbolic range of exactly one value,
3121 vr = get_value_range (cond);
3122 if (vr->type == VR_RANGE && vr->min == vr->max)
3127 tree op0 = TREE_OPERAND (cond, 0);
3128 tree op1 = TREE_OPERAND (cond, 1);
3130 /* We only deal with integral and pointer types. */
3131 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
3132 && !POINTER_TYPE_P (TREE_TYPE (op0)))
3137 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
3138 return compare_names (TREE_CODE (cond), op0, op1);
3139 else if (TREE_CODE (op0) == SSA_NAME)
3140 return compare_name_with_value (TREE_CODE (cond), op0, op1);
3141 else if (TREE_CODE (op1) == SSA_NAME)
3142 return compare_name_with_value (
3143 swap_tree_comparison (TREE_CODE (cond)), op1, op0);
3147 value_range_t *vr0, *vr1;
3149 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
3150 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
3153 return compare_ranges (TREE_CODE (cond), vr0, vr1);
3154 else if (vr0 && vr1 == NULL)
3155 return compare_range_with_value (TREE_CODE (cond), vr0, op1);
3156 else if (vr0 == NULL && vr1)
3157 return compare_range_with_value (
3158 swap_tree_comparison (TREE_CODE (cond)), vr1, op0);
3162 /* Anything else cannot be computed statically. */
3167 /* Visit conditional statement STMT. If we can determine which edge
3168 will be taken out of STMT's basic block, record it in
3169 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3170 SSA_PROP_VARYING. */
3172 static enum ssa_prop_result
3173 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
3177 *taken_edge_p = NULL;
3179 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3180 add ASSERT_EXPRs for them. */
3181 if (TREE_CODE (stmt) == SWITCH_EXPR)
3182 return SSA_PROP_VARYING;
3184 cond = COND_EXPR_COND (stmt);
3186 if (dump_file && (dump_flags & TDF_DETAILS))
3191 fprintf (dump_file, "\nVisiting conditional with predicate: ");
3192 print_generic_expr (dump_file, cond, 0);
3193 fprintf (dump_file, "\nWith known ranges\n");
3195 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
3197 fprintf (dump_file, "\t");
3198 print_generic_expr (dump_file, use, 0);
3199 fprintf (dump_file, ": ");
3200 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
3203 fprintf (dump_file, "\n");
3206 /* Compute the value of the predicate COND by checking the known
3207 ranges of each of its operands.
3209 Note that we cannot evaluate all the equivalent ranges here
3210 because those ranges may not yet be final and with the current
3211 propagation strategy, we cannot determine when the value ranges
3212 of the names in the equivalence set have changed.
3214 For instance, given the following code fragment
3218 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3222 Assume that on the first visit to i_14, i_5 has the temporary
3223 range [8, 8] because the second argument to the PHI function is
3224 not yet executable. We derive the range ~[0, 0] for i_14 and the
3225 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3226 the first time, since i_14 is equivalent to the range [8, 8], we
3227 determine that the predicate is always false.
3229 On the next round of propagation, i_13 is determined to be
3230 VARYING, which causes i_5 to drop down to VARYING. So, another
3231 visit to i_14 is scheduled. In this second visit, we compute the
3232 exact same range and equivalence set for i_14, namely ~[0, 0] and
3233 { i_5 }. But we did not have the previous range for i_5
3234 registered, so vrp_visit_assignment thinks that the range for
3235 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3236 is not visited again, which stops propagation from visiting
3237 statements in the THEN clause of that if().
3239 To properly fix this we would need to keep the previous range
3240 value for the names in the equivalence set. This way we would've
3241 discovered that from one visit to the other i_5 changed from
3242 range [8, 8] to VR_VARYING.
3244 However, fixing this apparent limitation may not be worth the
3245 additional checking. Testing on several code bases (GCC, DLV,
3246 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3247 4 more predicates folded in SPEC. */
3248 val = vrp_evaluate_conditional (cond, false);
3250 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
3252 if (dump_file && (dump_flags & TDF_DETAILS))
3254 fprintf (dump_file, "\nPredicate evaluates to: ");
3255 if (val == NULL_TREE)
3256 fprintf (dump_file, "DON'T KNOW\n");
3258 print_generic_stmt (dump_file, val, 0);
3261 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
3265 /* Evaluate statement STMT. If the statement produces a useful range,
3266 return SSA_PROP_INTERESTING and record the SSA name with the
3267 interesting range into *OUTPUT_P.
3269 If STMT is a conditional branch and we can determine its truth
3270 value, the taken edge is recorded in *TAKEN_EDGE_P.
3272 If STMT produces a varying value, return SSA_PROP_VARYING. */
3274 static enum ssa_prop_result
3275 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
3281 if (dump_file && (dump_flags & TDF_DETAILS))
3283 fprintf (dump_file, "\nVisiting statement:\n");
3284 print_generic_stmt (dump_file, stmt, dump_flags);
3285 fprintf (dump_file, "\n");
3288 ann = stmt_ann (stmt);
3289 if (TREE_CODE (stmt) == MODIFY_EXPR
3290 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3291 return vrp_visit_assignment (stmt, output_p);
3292 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3293 return vrp_visit_cond_stmt (stmt, taken_edge_p);
3295 /* All other statements produce nothing of interest for VRP, so mark
3296 their outputs varying and prevent further simulation. */
3297 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3298 set_value_range_to_varying (get_value_range (def));
3300 return SSA_PROP_VARYING;
3304 /* Meet operation for value ranges. Given two value ranges VR0 and
3305 VR1, store in VR0 the result of meeting VR0 and VR1.
3307 The meeting rules are as follows:
3309 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
3311 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
3312 union of VR0 and VR1. */
3315 vrp_meet (value_range_t *vr0, value_range_t *vr1)
3317 if (vr0->type == VR_UNDEFINED)
3319 copy_value_range (vr0, vr1);
3323 if (vr1->type == VR_UNDEFINED)
3325 /* Nothing to do. VR0 already has the resulting range. */
3329 if (vr0->type == VR_VARYING)
3331 /* Nothing to do. VR0 already has the resulting range. */
3335 if (vr1->type == VR_VARYING)
3337 set_value_range_to_varying (vr0);
3341 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
3343 /* If VR0 and VR1 have a non-empty intersection, compute the
3344 union of both ranges. */
3345 if (value_ranges_intersect_p (vr0, vr1))
3350 /* The lower limit of the new range is the minimum of the
3351 two ranges. If they cannot be compared, the result is
3353 cmp = compare_values (vr0->min, vr1->min);
3354 if (cmp == 0 || cmp == 1)
3360 set_value_range_to_varying (vr0);
3364 /* Similarly, the upper limit of the new range is the
3365 maximum of the two ranges. If they cannot be compared,
3366 the result is VARYING. */
3367 cmp = compare_values (vr0->max, vr1->max);
3368 if (cmp == 0 || cmp == -1)
3374 set_value_range_to_varying (vr0);
3378 /* The resulting set of equivalences is the intersection of
3380 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3381 bitmap_and_into (vr0->equiv, vr1->equiv);
3382 else if (vr0->equiv && !vr1->equiv)
3383 bitmap_clear (vr0->equiv);
3385 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
3390 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
3392 /* Two anti-ranges meet only if they are both identical. */
3393 if (compare_values (vr0->min, vr1->min) == 0
3394 && compare_values (vr0->max, vr1->max) == 0
3395 && compare_values (vr0->min, vr0->max) == 0)
3397 /* The resulting set of equivalences is the intersection of
3399 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3400 bitmap_and_into (vr0->equiv, vr1->equiv);
3401 else if (vr0->equiv && !vr1->equiv)
3402 bitmap_clear (vr0->equiv);
3407 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
3409 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
3410 meet only if the ranges have an empty intersection. The
3411 result of the meet operation is the anti-range. */
3412 if (!symbolic_range_p (vr0)
3413 && !symbolic_range_p (vr1)
3414 && !value_ranges_intersect_p (vr0, vr1))
3416 if (vr1->type == VR_ANTI_RANGE)
3417 copy_value_range (vr0, vr1);
3419 /* The resulting set of equivalences is the intersection of
3421 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3422 bitmap_and_into (vr0->equiv, vr1->equiv);
3423 else if (vr0->equiv && !vr1->equiv)
3424 bitmap_clear (vr0->equiv);
3435 /* The two range VR0 and VR1 do not meet. Before giving up and
3436 setting the result to VARYING, see if we can at least derive a
3437 useful anti-range. */
3438 if (!symbolic_range_p (vr0)
3439 && !range_includes_zero_p (vr0)
3440 && !symbolic_range_p (vr1)
3441 && !range_includes_zero_p (vr1))
3442 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
3444 set_value_range_to_varying (vr0);
3448 /* Visit all arguments for PHI node PHI that flow through executable
3449 edges. If a valid value range can be derived from all the incoming
3450 value ranges, set a new range for the LHS of PHI. */
3452 static enum ssa_prop_result
3453 vrp_visit_phi_node (tree phi)
3456 tree lhs = PHI_RESULT (phi);
3457 value_range_t *lhs_vr = get_value_range (lhs);
3458 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3460 copy_value_range (&vr_result, lhs_vr);
3462 if (dump_file && (dump_flags & TDF_DETAILS))
3464 fprintf (dump_file, "\nVisiting PHI node: ");
3465 print_generic_expr (dump_file, phi, dump_flags);
3468 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
3470 edge e = PHI_ARG_EDGE (phi, i);
3472 if (dump_file && (dump_flags & TDF_DETAILS))
3475 "\n Argument #%d (%d -> %d %sexecutable)\n",
3476 i, e->src->index, e->dest->index,
3477 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
3480 if (e->flags & EDGE_EXECUTABLE)
3482 tree arg = PHI_ARG_DEF (phi, i);
3483 value_range_t vr_arg;
3485 if (TREE_CODE (arg) == SSA_NAME)
3486 vr_arg = *(get_value_range (arg));
3489 vr_arg.type = VR_RANGE;
3492 vr_arg.equiv = NULL;
3495 if (dump_file && (dump_flags & TDF_DETAILS))
3497 fprintf (dump_file, "\t");
3498 print_generic_expr (dump_file, arg, dump_flags);
3499 fprintf (dump_file, "\n\tValue: ");
3500 dump_value_range (dump_file, &vr_arg);
3501 fprintf (dump_file, "\n");
3504 vrp_meet (&vr_result, &vr_arg);
3506 if (vr_result.type == VR_VARYING)
3511 if (vr_result.type == VR_VARYING)
3514 /* To prevent infinite iterations in the algorithm, derive ranges
3515 when the new value is slightly bigger or smaller than the
3517 if (lhs_vr->type == VR_RANGE)
3519 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
3521 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
3522 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
3524 /* If the new minimum is smaller or larger than the previous
3525 one, go all the way to -INF. In the first case, to avoid
3526 iterating millions of times to reach -INF, and in the
3527 other case to avoid infinite bouncing between different
3529 if (cmp_min > 0 || cmp_min < 0)
3530 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
3532 /* Similarly, if the new maximum is smaller or larger than
3533 the previous one, go all the way to +INF. */
3534 if (cmp_max < 0 || cmp_max > 0)
3535 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
3537 /* If we ended up with a (-INF, +INF) range, set it to
3539 if (vr_result.min == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))
3540 && vr_result.max == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)))
3545 /* If the new range is different than the previous value, keep
3547 if (update_value_range (lhs, &vr_result))
3548 return SSA_PROP_INTERESTING;
3550 /* Nothing changed, don't add outgoing edges. */
3551 return SSA_PROP_NOT_INTERESTING;
3553 /* No match found. Set the LHS to VARYING. */
3555 set_value_range_to_varying (lhs_vr);
3556 return SSA_PROP_VARYING;
3559 /* Simplify a division or modulo operator to a right shift or
3560 bitwise and if the first operand is unsigned or is greater
3561 than zero and the second operand is an exact power of two. */
3564 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
3567 tree op = TREE_OPERAND (rhs, 0);
3568 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
3570 if (TYPE_UNSIGNED (TREE_TYPE (op)))
3572 val = integer_one_node;
3576 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node);
3579 if (val && integer_onep (val))
3582 tree op0 = TREE_OPERAND (rhs, 0);
3583 tree op1 = TREE_OPERAND (rhs, 1);
3585 if (rhs_code == TRUNC_DIV_EXPR)
3587 t = build_int_cst (NULL_TREE, tree_log2 (op1));
3588 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
3592 t = build_int_cst (TREE_TYPE (op1), 1);
3593 t = int_const_binop (MINUS_EXPR, op1, t, 0);
3594 t = fold_convert (TREE_TYPE (op0), t);
3595 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
3598 TREE_OPERAND (stmt, 1) = t;
3603 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
3604 ABS_EXPR. If the operand is <= 0, then simplify the
3605 ABS_EXPR into a NEGATE_EXPR. */
3608 simplify_abs_using_ranges (tree stmt, tree rhs)
3611 tree op = TREE_OPERAND (rhs, 0);
3612 tree type = TREE_TYPE (op);
3613 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
3615 if (TYPE_UNSIGNED (type))
3617 val = integer_zero_node;
3621 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node);
3624 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node);
3628 if (integer_zerop (val))
3629 val = integer_one_node;
3630 else if (integer_onep (val))
3631 val = integer_zero_node;
3636 && (integer_onep (val) || integer_zerop (val)))
3640 if (integer_onep (val))
3641 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
3645 TREE_OPERAND (stmt, 1) = t;
3651 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
3652 a known value range VR.
3654 If there is one and only one value which will satisfy the
3655 conditional, then return that value. Else return NULL. */
3658 test_for_singularity (enum tree_code cond_code, tree op0,
3659 tree op1, value_range_t *vr)
3664 /* Extract minimum/maximum values which satisfy the
3665 the conditional as it was written. */
3666 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
3668 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
3671 if (cond_code == LT_EXPR)
3673 tree one = build_int_cst (TREE_TYPE (op0), 1);
3674 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
3677 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
3679 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
3682 if (cond_code == GT_EXPR)
3684 tree one = build_int_cst (TREE_TYPE (op0), 1);
3685 max = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), max, one);
3689 /* Now refine the minimum and maximum values using any
3690 value range information we have for op0. */
3693 if (compare_values (vr->min, min) == -1)
3697 if (compare_values (vr->max, max) == 1)
3702 /* If the new min/max values have converged to a
3703 single value, then there is only one value which
3704 can satisfy the condition, return that value. */
3705 if (min == max && is_gimple_min_invariant (min))
3711 /* Simplify a conditional using a relational operator to an equality
3712 test if the range information indicates only one value can satisfy
3713 the original conditional. */
3716 simplify_cond_using_ranges (tree stmt)
3718 tree cond = COND_EXPR_COND (stmt);
3719 tree op0 = TREE_OPERAND (cond, 0);
3720 tree op1 = TREE_OPERAND (cond, 1);
3721 enum tree_code cond_code = TREE_CODE (cond);
3723 if (cond_code != NE_EXPR
3724 && cond_code != EQ_EXPR
3725 && TREE_CODE (op0) == SSA_NAME
3726 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
3727 && is_gimple_min_invariant (op1))
3729 value_range_t *vr = get_value_range (op0);
3731 /* If we have range information for OP0, then we might be
3732 able to simplify this conditional. */
3733 if (vr->type == VR_RANGE)
3735 tree new = test_for_singularity (cond_code, op0, op1, vr);
3741 fprintf (dump_file, "Simplified relational ");
3742 print_generic_expr (dump_file, cond, 0);
3743 fprintf (dump_file, " into ");
3746 COND_EXPR_COND (stmt)
3747 = build (EQ_EXPR, boolean_type_node, op0, new);
3752 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
3753 fprintf (dump_file, "\n");
3759 /* Try again after inverting the condition. We only deal
3760 with integral types here, so no need to worry about
3761 issues with inverting FP comparisons. */
3762 cond_code = invert_tree_comparison (cond_code, false);
3763 new = test_for_singularity (cond_code, op0, op1, vr);
3769 fprintf (dump_file, "Simplified relational ");
3770 print_generic_expr (dump_file, cond, 0);
3771 fprintf (dump_file, " into ");
3774 COND_EXPR_COND (stmt)
3775 = build (NE_EXPR, boolean_type_node, op0, new);
3780 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
3781 fprintf (dump_file, "\n");
3790 /* Simplify STMT using ranges if possible. */
3793 simplify_stmt_using_ranges (tree stmt)
3795 if (TREE_CODE (stmt) == MODIFY_EXPR)
3797 tree rhs = TREE_OPERAND (stmt, 1);
3798 enum tree_code rhs_code = TREE_CODE (rhs);
3800 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
3801 and BIT_AND_EXPR respectively if the first operand is greater
3802 than zero and the second operand is an exact power of two. */
3803 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
3804 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
3805 && integer_pow2p (TREE_OPERAND (rhs, 1)))
3806 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
3808 /* Transform ABS (X) into X or -X as appropriate. */
3809 if (rhs_code == ABS_EXPR
3810 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
3811 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
3812 simplify_abs_using_ranges (stmt, rhs);
3814 else if (TREE_CODE (stmt) == COND_EXPR
3815 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
3817 simplify_cond_using_ranges (stmt);
3823 /* Traverse all the blocks folding conditionals with known ranges. */
3829 prop_value_t *single_val_range;
3830 bool do_value_subst_p;
3834 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
3835 dump_all_value_ranges (dump_file);
3836 fprintf (dump_file, "\n");
3839 /* We may have ended with ranges that have exactly one value. Those
3840 values can be substituted as any other copy/const propagated
3841 value using substitute_and_fold. */
3842 single_val_range = xmalloc (num_ssa_names * sizeof (*single_val_range));
3843 memset (single_val_range, 0, num_ssa_names * sizeof (*single_val_range));
3845 do_value_subst_p = false;
3846 for (i = 0; i < num_ssa_names; i++)
3848 && vr_value[i]->type == VR_RANGE
3849 && vr_value[i]->min == vr_value[i]->max)
3851 single_val_range[i].value = vr_value[i]->min;
3852 do_value_subst_p = true;
3855 if (!do_value_subst_p)
3857 /* We found no single-valued ranges, don't waste time trying to
3858 do single value substitution in substitute_and_fold. */
3859 free (single_val_range);
3860 single_val_range = NULL;
3863 substitute_and_fold (single_val_range, true);
3865 /* Free allocated memory. */
3866 for (i = 0; i < num_ssa_names; i++)
3869 BITMAP_FREE (vr_value[i]->equiv);
3873 free (single_val_range);
3878 /* Main entry point to VRP (Value Range Propagation). This pass is
3879 loosely based on J. R. C. Patterson, ``Accurate Static Branch
3880 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
3881 Programming Language Design and Implementation, pp. 67-78, 1995.
3882 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
3884 This is essentially an SSA-CCP pass modified to deal with ranges
3885 instead of constants.
3887 While propagating ranges, we may find that two or more SSA name
3888 have equivalent, though distinct ranges. For instance,
3891 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
3893 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
3897 In the code above, pointer p_5 has range [q_2, q_2], but from the
3898 code we can also determine that p_5 cannot be NULL and, if q_2 had
3899 a non-varying range, p_5's range should also be compatible with it.
3901 These equivalences are created by two expressions: ASSERT_EXPR and
3902 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
3903 result of another assertion, then we can use the fact that p_5 and
3904 p_4 are equivalent when evaluating p_5's range.
3906 Together with value ranges, we also propagate these equivalences
3907 between names so that we can take advantage of information from
3908 multiple ranges when doing final replacement. Note that this
3909 equivalency relation is transitive but not symmetric.
3911 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
3912 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
3913 in contexts where that assertion does not hold (e.g., in line 6).
3915 TODO, the main difference between this pass and Patterson's is that
3916 we do not propagate edge probabilities. We only compute whether
3917 edges can be taken or not. That is, instead of having a spectrum
3918 of jump probabilities between 0 and 1, we only deal with 0, 1 and
3919 DON'T KNOW. In the future, it may be worthwhile to propagate
3920 probabilities to aid branch prediction. */
3925 insert_range_assertions ();
3927 cfg_loops = loop_optimizer_init (NULL);
3929 scev_initialize (cfg_loops);
3932 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
3938 loop_optimizer_finalize (cfg_loops, NULL);
3939 current_loops = NULL;
3942 remove_range_assertions ();
3948 return flag_tree_vrp != 0;
3951 struct tree_opt_pass pass_vrp =
3954 gate_vrp, /* gate */
3955 execute_vrp, /* execute */
3958 0, /* static_pass_number */
3959 TV_TREE_VRP, /* tv_id */
3960 PROP_ssa | PROP_alias, /* properties_required */
3961 0, /* properties_provided */
3962 0, /* properties_destroyed */
3963 0, /* todo_flags_start */
3968 | TODO_update_ssa, /* todo_flags_finish */