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
777 not its anti-range. */
779 || limit_vr->type == VR_ANTI_RANGE)
790 /* If MIN and MAX cover the whole range for their type, then
791 just use the original LIMIT. */
792 if (INTEGRAL_TYPE_P (type)
793 && min == TYPE_MIN_VALUE (type)
794 && max == TYPE_MAX_VALUE (type))
797 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
799 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
801 min = TYPE_MIN_VALUE (type);
803 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
807 /* If LIMIT_VR is of the form [N1, N2], we need to build the
808 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
813 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
814 if (cond_code == LT_EXPR)
816 tree one = build_int_cst (type, 1);
817 max = fold_build2 (MINUS_EXPR, type, max, one);
820 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
822 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
824 max = TYPE_MAX_VALUE (type);
826 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
830 /* If LIMIT_VR is of the form [N1, N2], we need to build the
831 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
836 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
837 if (cond_code == GT_EXPR)
839 tree one = build_int_cst (type, 1);
840 min = fold_build2 (PLUS_EXPR, type, min, one);
843 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
848 /* If VAR already had a known range and the two ranges have a
849 non-empty intersection, we can refine the resulting range.
850 Since the assert expression creates an equivalency and at the
851 same time it asserts a predicate, we can take the intersection of
852 the two ranges to get better precision. */
853 var_vr = get_value_range (var);
854 if (var_vr->type == VR_RANGE
855 && vr_p->type == VR_RANGE
856 && value_ranges_intersect_p (var_vr, vr_p))
858 /* Use the larger of the two minimums. */
859 if (compare_values (vr_p->min, var_vr->min) == -1)
864 /* Use the smaller of the two maximums. */
865 if (compare_values (vr_p->max, var_vr->max) == 1)
870 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
875 /* Extract range information from SSA name VAR and store it in VR. If
876 VAR has an interesting range, use it. Otherwise, create the
877 range [VAR, VAR] and return it. This is useful in situations where
878 we may have conditionals testing values of VARYING names. For
885 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
889 extract_range_from_ssa_name (value_range_t *vr, tree var)
891 value_range_t *var_vr = get_value_range (var);
893 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
894 copy_value_range (vr, var_vr);
896 set_value_range (vr, VR_RANGE, var, var, NULL);
898 add_equivalence (vr->equiv, var);
902 /* Wrapper around int_const_binop. If the operation overflows and we
903 are not using wrapping arithmetic, then adjust the result to be
904 -INF or +INF depending on CODE, VAL1 and VAL2. */
907 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
912 return int_const_binop (code, val1, val2, 0);
914 /* If we are not using wrapping arithmetic, operate symbolically
916 res = int_const_binop (code, val1, val2, 0);
918 /* If the operation overflowed but neither VAL1 nor VAL2 are
919 overflown, return -INF or +INF depending on the operation
920 and the combination of signs of the operands. */
921 if (TREE_OVERFLOW (res)
922 && !TREE_OVERFLOW (val1)
923 && !TREE_OVERFLOW (val2))
925 int sgn1 = tree_int_cst_sgn (val1);
926 int sgn2 = tree_int_cst_sgn (val2);
928 /* Notice that we only need to handle the restricted set of
929 operations handled by extract_range_from_binary_expr.
930 Among them, only multiplication, addition and subtraction
931 can yield overflow without overflown operands because we
932 are working with integral types only... except in the
933 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
936 /* For multiplication, the sign of the overflow is given
937 by the comparison of the signs of the operands. */
938 if ((code == MULT_EXPR && sgn1 == sgn2)
939 /* For addition, the operands must be of the same sign
940 to yield an overflow. Its sign is therefore that
941 of one of the operands, for example the first. */
942 || (code == PLUS_EXPR && sgn1 > 0)
943 /* For subtraction, the operands must be of different
944 signs to yield an overflow. Its sign is therefore
945 that of the first operand or the opposite of that
946 of the second operand. */
947 || (code == MINUS_EXPR && sgn1 > 0)
948 /* For division, the only case is -INF / -1 = +INF. */
949 || code == TRUNC_DIV_EXPR
950 || code == FLOOR_DIV_EXPR
951 || code == CEIL_DIV_EXPR
952 || code == EXACT_DIV_EXPR
953 || code == ROUND_DIV_EXPR)
954 return TYPE_MAX_VALUE (TREE_TYPE (res));
956 return TYPE_MIN_VALUE (TREE_TYPE (res));
963 /* Extract range information from a binary expression EXPR based on
964 the ranges of each of its operands and the expression code. */
967 extract_range_from_binary_expr (value_range_t *vr, tree expr)
969 enum tree_code code = TREE_CODE (expr);
970 tree op0, op1, min, max;
972 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
973 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
975 /* Not all binary expressions can be applied to ranges in a
976 meaningful way. Handle only arithmetic operations. */
977 if (code != PLUS_EXPR
978 && code != MINUS_EXPR
980 && code != TRUNC_DIV_EXPR
981 && code != FLOOR_DIV_EXPR
982 && code != CEIL_DIV_EXPR
983 && code != EXACT_DIV_EXPR
984 && code != ROUND_DIV_EXPR
987 && code != TRUTH_ANDIF_EXPR
988 && code != TRUTH_ORIF_EXPR
989 && code != TRUTH_AND_EXPR
990 && code != TRUTH_OR_EXPR
991 && code != TRUTH_XOR_EXPR)
993 set_value_range_to_varying (vr);
997 /* Get value ranges for each operand. For constant operands, create
998 a new value range with the operand to simplify processing. */
999 op0 = TREE_OPERAND (expr, 0);
1000 if (TREE_CODE (op0) == SSA_NAME)
1001 vr0 = *(get_value_range (op0));
1002 else if (is_gimple_min_invariant (op0))
1003 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1005 set_value_range_to_varying (&vr0);
1007 op1 = TREE_OPERAND (expr, 1);
1008 if (TREE_CODE (op1) == SSA_NAME)
1009 vr1 = *(get_value_range (op1));
1010 else if (is_gimple_min_invariant (op1))
1011 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1013 set_value_range_to_varying (&vr1);
1015 /* If either range is UNDEFINED, so is the result. */
1016 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1018 set_value_range_to_undefined (vr);
1022 /* Refuse to operate on VARYING ranges, ranges of different kinds
1023 and symbolic ranges. TODO, we may be able to derive anti-ranges
1025 if (vr0.type == VR_VARYING
1026 || vr1.type == VR_VARYING
1027 || vr0.type != vr1.type
1028 || symbolic_range_p (&vr0)
1029 || symbolic_range_p (&vr1))
1031 set_value_range_to_varying (vr);
1035 /* Now evaluate the expression to determine the new range. */
1036 if (POINTER_TYPE_P (TREE_TYPE (expr))
1037 || POINTER_TYPE_P (TREE_TYPE (op0))
1038 || POINTER_TYPE_P (TREE_TYPE (op1)))
1040 /* For pointer types, we are really only interested in asserting
1041 whether the expression evaluates to non-NULL. FIXME, we used
1042 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1043 ivopts is generating expressions with pointer multiplication
1045 if (code == PLUS_EXPR)
1047 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1048 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1049 else if (range_is_null (&vr0) && range_is_null (&vr1))
1050 set_value_range_to_null (vr, TREE_TYPE (expr));
1052 set_value_range_to_varying (vr);
1056 /* Subtracting from a pointer, may yield 0, so just drop the
1057 resulting range to varying. */
1058 set_value_range_to_varying (vr);
1064 /* For integer ranges, apply the operation to each end of the
1065 range and see what we end up with. */
1066 if (code == TRUTH_ANDIF_EXPR
1067 || code == TRUTH_ORIF_EXPR
1068 || code == TRUTH_AND_EXPR
1069 || code == TRUTH_OR_EXPR
1070 || code == TRUTH_XOR_EXPR)
1072 /* Boolean expressions cannot be folded with int_const_binop. */
1073 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1074 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1076 else if (code == PLUS_EXPR
1078 || code == MAX_EXPR)
1080 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1081 VR_VARYING. It would take more effort to compute a precise
1082 range for such a case. For example, if we have op0 == 1 and
1083 op1 == -1 with their ranges both being ~[0,0], we would have
1084 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1085 Note that we are guaranteed to have vr0.type == vr1.type at
1087 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1089 set_value_range_to_varying (vr);
1093 /* For operations that make the resulting range directly
1094 proportional to the original ranges, apply the operation to
1095 the same end of each range. */
1096 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1097 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1099 else if (code == MULT_EXPR
1100 || code == TRUNC_DIV_EXPR
1101 || code == FLOOR_DIV_EXPR
1102 || code == CEIL_DIV_EXPR
1103 || code == EXACT_DIV_EXPR
1104 || code == ROUND_DIV_EXPR)
1109 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1110 drop to VR_VARYING. It would take more effort to compute a
1111 precise range for such a case. For example, if we have
1112 op0 == 65536 and op1 == 65536 with their ranges both being
1113 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1114 we cannot claim that the product is in ~[0,0]. Note that we
1115 are guaranteed to have vr0.type == vr1.type at this
1117 if (code == MULT_EXPR
1118 && vr0.type == VR_ANTI_RANGE
1119 && (flag_wrapv || TYPE_UNSIGNED (TREE_TYPE (op0))))
1121 set_value_range_to_varying (vr);
1125 /* Multiplications and divisions are a bit tricky to handle,
1126 depending on the mix of signs we have in the two ranges, we
1127 need to operate on different values to get the minimum and
1128 maximum values for the new range. One approach is to figure
1129 out all the variations of range combinations and do the
1132 However, this involves several calls to compare_values and it
1133 is pretty convoluted. It's simpler to do the 4 operations
1134 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1135 MAX1) and then figure the smallest and largest values to form
1138 /* Divisions by zero result in a VARYING value. */
1139 if (code != MULT_EXPR && range_includes_zero_p (&vr1))
1141 set_value_range_to_varying (vr);
1145 /* Compute the 4 cross operations. */
1146 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1148 val[1] = (vr1.max != vr1.min)
1149 ? vrp_int_const_binop (code, vr0.min, vr1.max)
1152 val[2] = (vr0.max != vr0.min)
1153 ? vrp_int_const_binop (code, vr0.max, vr1.min)
1156 val[3] = (vr0.min != vr0.max && vr1.min != vr1.max)
1157 ? vrp_int_const_binop (code, vr0.max, vr1.max)
1160 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1164 for (i = 1; i < 4; i++)
1166 if (TREE_OVERFLOW (min) || TREE_OVERFLOW (max))
1171 if (TREE_OVERFLOW (val[i]))
1173 /* If we found an overflowed value, set MIN and MAX
1174 to it so that we set the resulting range to
1180 if (compare_values (val[i], min) == -1)
1183 if (compare_values (val[i], max) == 1)
1188 else if (code == MINUS_EXPR)
1190 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1191 VR_VARYING. It would take more effort to compute a precise
1192 range for such a case. For example, if we have op0 == 1 and
1193 op1 == 1 with their ranges both being ~[0,0], we would have
1194 op0 - op1 == 0, so we cannot claim that the difference is in
1195 ~[0,0]. Note that we are guaranteed to have
1196 vr0.type == vr1.type at this point. */
1197 if (vr0.type == VR_ANTI_RANGE)
1199 set_value_range_to_varying (vr);
1203 /* For MINUS_EXPR, apply the operation to the opposite ends of
1205 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1206 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1211 /* If either MIN or MAX overflowed, then set the resulting range to
1213 if (TREE_OVERFLOW (min) || TREE_OVERFLOW (max))
1215 set_value_range_to_varying (vr);
1219 cmp = compare_values (min, max);
1220 if (cmp == -2 || cmp == 1)
1222 /* If the new range has its limits swapped around (MIN > MAX),
1223 then the operation caused one of them to wrap around, mark
1224 the new range VARYING. */
1225 set_value_range_to_varying (vr);
1228 set_value_range (vr, vr0.type, min, max, NULL);
1232 /* Extract range information from a unary expression EXPR based on
1233 the range of its operand and the expression code. */
1236 extract_range_from_unary_expr (value_range_t *vr, tree expr)
1238 enum tree_code code = TREE_CODE (expr);
1241 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1243 /* Refuse to operate on certain unary expressions for which we
1244 cannot easily determine a resulting range. */
1245 if (code == FIX_TRUNC_EXPR
1246 || code == FIX_CEIL_EXPR
1247 || code == FIX_FLOOR_EXPR
1248 || code == FIX_ROUND_EXPR
1249 || code == FLOAT_EXPR
1250 || code == BIT_NOT_EXPR
1251 || code == NON_LVALUE_EXPR
1252 || code == CONJ_EXPR)
1254 set_value_range_to_varying (vr);
1258 /* Get value ranges for the operand. For constant operands, create
1259 a new value range with the operand to simplify processing. */
1260 op0 = TREE_OPERAND (expr, 0);
1261 if (TREE_CODE (op0) == SSA_NAME)
1262 vr0 = *(get_value_range (op0));
1263 else if (is_gimple_min_invariant (op0))
1264 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1266 set_value_range_to_varying (&vr0);
1268 /* If VR0 is UNDEFINED, so is the result. */
1269 if (vr0.type == VR_UNDEFINED)
1271 set_value_range_to_undefined (vr);
1275 /* Refuse to operate on varying and symbolic ranges. Also, if the
1276 operand is neither a pointer nor an integral type, set the
1277 resulting range to VARYING. TODO, in some cases we may be able
1278 to derive anti-ranges (like non-zero values). */
1279 if (vr0.type == VR_VARYING
1280 || (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
1281 && !POINTER_TYPE_P (TREE_TYPE (op0)))
1282 || symbolic_range_p (&vr0))
1284 set_value_range_to_varying (vr);
1288 /* If the expression involves pointers, we are only interested in
1289 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1290 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
1292 if (range_is_nonnull (&vr0) || tree_expr_nonzero_p (expr))
1293 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1294 else if (range_is_null (&vr0))
1295 set_value_range_to_null (vr, TREE_TYPE (expr));
1297 set_value_range_to_varying (vr);
1302 /* Handle unary expressions on integer ranges. */
1303 if (code == NOP_EXPR || code == CONVERT_EXPR)
1305 tree inner_type = TREE_TYPE (op0);
1306 tree outer_type = TREE_TYPE (expr);
1308 /* If VR0 represents a simple range, then try to convert
1309 the min and max values for the range to the same type
1310 as OUTER_TYPE. If the results compare equal to VR0's
1311 min and max values and the new min is still less than
1312 or equal to the new max, then we can safely use the newly
1313 computed range for EXPR. This allows us to compute
1314 accurate ranges through many casts. */
1315 if (vr0.type == VR_RANGE)
1317 tree new_min, new_max;
1319 /* Convert VR0's min/max to OUTER_TYPE. */
1320 new_min = fold_convert (outer_type, vr0.min);
1321 new_max = fold_convert (outer_type, vr0.max);
1323 /* Verify the new min/max values are gimple values and
1324 that they compare equal to VR0's min/max values. */
1325 if (is_gimple_val (new_min)
1326 && is_gimple_val (new_max)
1327 && tree_int_cst_equal (new_min, vr0.min)
1328 && tree_int_cst_equal (new_max, vr0.max)
1329 && compare_values (new_min, new_max) <= 0
1330 && compare_values (new_min, new_max) >= -2)
1332 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
1337 /* When converting types of different sizes, set the result to
1338 VARYING. Things like sign extensions and precision loss may
1339 change the range. For instance, if x_3 is of type 'long long
1340 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1341 is impossible to know at compile time whether y_5 will be
1343 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
1344 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
1346 set_value_range_to_varying (vr);
1351 /* Apply the operation to each end of the range and see what we end
1353 if (code == NEGATE_EXPR
1354 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1356 /* NEGATE_EXPR flips the range around. */
1357 min = (vr0.max == TYPE_MAX_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
1358 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1359 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1361 max = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)) && !flag_wrapv)
1362 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1363 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1365 else if (code == ABS_EXPR
1366 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1368 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1371 && ((vr0.type == VR_RANGE
1372 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1373 || (vr0.type == VR_ANTI_RANGE
1374 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
1375 && !range_includes_zero_p (&vr0))))
1377 set_value_range_to_varying (vr);
1381 /* ABS_EXPR may flip the range around, if the original range
1382 included negative values. */
1383 min = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1384 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1385 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1387 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1389 cmp = compare_values (min, max);
1391 /* If a VR_ANTI_RANGEs contains zero, then we have
1392 ~[-INF, min(MIN, MAX)]. */
1393 if (vr0.type == VR_ANTI_RANGE)
1395 if (range_includes_zero_p (&vr0))
1397 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
1399 /* Take the lower of the two values. */
1403 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1404 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1405 flag_wrapv is set and the original anti-range doesn't include
1406 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1407 min = (flag_wrapv && vr0.min != type_min_value
1408 ? int_const_binop (PLUS_EXPR,
1410 integer_one_node, 0)
1415 /* All else has failed, so create the range [0, INF], even for
1416 flag_wrapv since TYPE_MIN_VALUE is in the original
1418 vr0.type = VR_RANGE;
1419 min = build_int_cst (TREE_TYPE (expr), 0);
1420 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
1424 /* If the range contains zero then we know that the minimum value in the
1425 range will be zero. */
1426 else if (range_includes_zero_p (&vr0))
1430 min = build_int_cst (TREE_TYPE (expr), 0);
1434 /* If the range was reversed, swap MIN and MAX. */
1445 /* Otherwise, operate on each end of the range. */
1446 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1447 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1450 cmp = compare_values (min, max);
1451 if (cmp == -2 || cmp == 1)
1453 /* If the new range has its limits swapped around (MIN > MAX),
1454 then the operation caused one of them to wrap around, mark
1455 the new range VARYING. */
1456 set_value_range_to_varying (vr);
1459 set_value_range (vr, vr0.type, min, max, NULL);
1463 /* Extract range information from a comparison expression EXPR based
1464 on the range of its operand and the expression code. */
1467 extract_range_from_comparison (value_range_t *vr, tree expr)
1469 tree val = vrp_evaluate_conditional (expr, false);
1472 /* Since this expression was found on the RHS of an assignment,
1473 its type may be different from _Bool. Convert VAL to EXPR's
1475 val = fold_convert (TREE_TYPE (expr), val);
1476 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
1479 set_value_range_to_varying (vr);
1483 /* Try to compute a useful range out of expression EXPR and store it
1487 extract_range_from_expr (value_range_t *vr, tree expr)
1489 enum tree_code code = TREE_CODE (expr);
1491 if (code == ASSERT_EXPR)
1492 extract_range_from_assert (vr, expr);
1493 else if (code == SSA_NAME)
1494 extract_range_from_ssa_name (vr, expr);
1495 else if (TREE_CODE_CLASS (code) == tcc_binary
1496 || code == TRUTH_ANDIF_EXPR
1497 || code == TRUTH_ORIF_EXPR
1498 || code == TRUTH_AND_EXPR
1499 || code == TRUTH_OR_EXPR
1500 || code == TRUTH_XOR_EXPR)
1501 extract_range_from_binary_expr (vr, expr);
1502 else if (TREE_CODE_CLASS (code) == tcc_unary)
1503 extract_range_from_unary_expr (vr, expr);
1504 else if (TREE_CODE_CLASS (code) == tcc_comparison)
1505 extract_range_from_comparison (vr, expr);
1506 else if (vrp_expr_computes_nonzero (expr))
1507 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1508 else if (is_gimple_min_invariant (expr))
1509 set_value_range (vr, VR_RANGE, expr, expr, NULL);
1511 set_value_range_to_varying (vr);
1514 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1515 would be profitable to adjust VR using scalar evolution information
1516 for VAR. If so, update VR with the new limits. */
1519 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
1522 tree init, step, chrec;
1525 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1526 better opportunities than a regular range, but I'm not sure. */
1527 if (vr->type == VR_ANTI_RANGE)
1530 chrec = analyze_scalar_evolution (loop, var);
1531 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
1534 init = CHREC_LEFT (chrec);
1535 step = CHREC_RIGHT (chrec);
1537 /* If STEP is symbolic, we can't know whether INIT will be the
1538 minimum or maximum value in the range. */
1539 if (!is_gimple_min_invariant (step))
1542 /* Do not adjust ranges when chrec may wrap. */
1543 if (scev_probably_wraps_p (chrec_type (chrec), init, step, stmt,
1544 cfg_loops->parray[CHREC_VARIABLE (chrec)],
1548 if (!POINTER_TYPE_P (TREE_TYPE (init))
1549 && (vr->type == VR_VARYING || vr->type == VR_UNDEFINED))
1551 /* For VARYING or UNDEFINED ranges, just about anything we get
1552 from scalar evolutions should be better. */
1554 set_value_range (vr, VR_RANGE, TYPE_MIN_VALUE (TREE_TYPE (init)),
1557 set_value_range (vr, VR_RANGE, init, TYPE_MAX_VALUE (TREE_TYPE (init)),
1560 else if (vr->type == VR_RANGE)
1567 /* INIT is the maximum value. If INIT is lower than VR->MAX
1568 but no smaller than VR->MIN, set VR->MAX to INIT. */
1569 if (compare_values (init, max) == -1)
1573 /* If we just created an invalid range with the minimum
1574 greater than the maximum, take the minimum all the
1576 if (compare_values (min, max) == 1)
1577 min = TYPE_MIN_VALUE (TREE_TYPE (min));
1582 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
1583 if (compare_values (init, min) == 1)
1587 /* If we just created an invalid range with the minimum
1588 greater than the maximum, take the maximum all the
1590 if (compare_values (min, max) == 1)
1591 max = TYPE_MAX_VALUE (TREE_TYPE (max));
1595 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
1600 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
1602 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
1603 all the values in the ranges.
1605 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
1607 - Return NULL_TREE if it is not always possible to determine the
1608 value of the comparison. */
1612 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1)
1614 /* VARYING or UNDEFINED ranges cannot be compared. */
1615 if (vr0->type == VR_VARYING
1616 || vr0->type == VR_UNDEFINED
1617 || vr1->type == VR_VARYING
1618 || vr1->type == VR_UNDEFINED)
1621 /* Anti-ranges need to be handled separately. */
1622 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
1624 /* If both are anti-ranges, then we cannot compute any
1626 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
1629 /* These comparisons are never statically computable. */
1636 /* Equality can be computed only between a range and an
1637 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
1638 if (vr0->type == VR_RANGE)
1640 /* To simplify processing, make VR0 the anti-range. */
1641 value_range_t *tmp = vr0;
1646 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
1648 if (compare_values (vr0->min, vr1->min) == 0
1649 && compare_values (vr0->max, vr1->max) == 0)
1650 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
1655 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
1656 operands around and change the comparison code. */
1657 if (comp == GT_EXPR || comp == GE_EXPR)
1660 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
1666 if (comp == EQ_EXPR)
1668 /* Equality may only be computed if both ranges represent
1669 exactly one value. */
1670 if (compare_values (vr0->min, vr0->max) == 0
1671 && compare_values (vr1->min, vr1->max) == 0)
1673 int cmp_min = compare_values (vr0->min, vr1->min);
1674 int cmp_max = compare_values (vr0->max, vr1->max);
1675 if (cmp_min == 0 && cmp_max == 0)
1676 return boolean_true_node;
1677 else if (cmp_min != -2 && cmp_max != -2)
1678 return boolean_false_node;
1683 else if (comp == NE_EXPR)
1687 /* If VR0 is completely to the left or completely to the right
1688 of VR1, they are always different. Notice that we need to
1689 make sure that both comparisons yield similar results to
1690 avoid comparing values that cannot be compared at
1692 cmp1 = compare_values (vr0->max, vr1->min);
1693 cmp2 = compare_values (vr0->min, vr1->max);
1694 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
1695 return boolean_true_node;
1697 /* If VR0 and VR1 represent a single value and are identical,
1699 else if (compare_values (vr0->min, vr0->max) == 0
1700 && compare_values (vr1->min, vr1->max) == 0
1701 && compare_values (vr0->min, vr1->min) == 0
1702 && compare_values (vr0->max, vr1->max) == 0)
1703 return boolean_false_node;
1705 /* Otherwise, they may or may not be different. */
1709 else if (comp == LT_EXPR || comp == LE_EXPR)
1713 /* If VR0 is to the left of VR1, return true. */
1714 tst = compare_values (vr0->max, vr1->min);
1715 if ((comp == LT_EXPR && tst == -1)
1716 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
1717 return boolean_true_node;
1719 /* If VR0 is to the right of VR1, return false. */
1720 tst = compare_values (vr0->min, vr1->max);
1721 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
1722 || (comp == LE_EXPR && tst == 1))
1723 return boolean_false_node;
1725 /* Otherwise, we don't know. */
1733 /* Given a value range VR, a value VAL and a comparison code COMP, return
1734 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
1735 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
1736 always returns false. Return NULL_TREE if it is not always
1737 possible to determine the value of the comparison. */
1740 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val)
1742 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
1745 /* Anti-ranges need to be handled separately. */
1746 if (vr->type == VR_ANTI_RANGE)
1748 /* For anti-ranges, the only predicates that we can compute at
1749 compile time are equality and inequality. */
1756 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
1757 if (value_inside_range (val, vr) == 1)
1758 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
1763 if (comp == EQ_EXPR)
1765 /* EQ_EXPR may only be computed if VR represents exactly
1767 if (compare_values (vr->min, vr->max) == 0)
1769 int cmp = compare_values (vr->min, val);
1771 return boolean_true_node;
1772 else if (cmp == -1 || cmp == 1 || cmp == 2)
1773 return boolean_false_node;
1775 else if (compare_values (val, vr->min) == -1
1776 || compare_values (vr->max, val) == -1)
1777 return boolean_false_node;
1781 else if (comp == NE_EXPR)
1783 /* If VAL is not inside VR, then they are always different. */
1784 if (compare_values (vr->max, val) == -1
1785 || compare_values (vr->min, val) == 1)
1786 return boolean_true_node;
1788 /* If VR represents exactly one value equal to VAL, then return
1790 if (compare_values (vr->min, vr->max) == 0
1791 && compare_values (vr->min, val) == 0)
1792 return boolean_false_node;
1794 /* Otherwise, they may or may not be different. */
1797 else if (comp == LT_EXPR || comp == LE_EXPR)
1801 /* If VR is to the left of VAL, return true. */
1802 tst = compare_values (vr->max, val);
1803 if ((comp == LT_EXPR && tst == -1)
1804 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
1805 return boolean_true_node;
1807 /* If VR is to the right of VAL, return false. */
1808 tst = compare_values (vr->min, val);
1809 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
1810 || (comp == LE_EXPR && tst == 1))
1811 return boolean_false_node;
1813 /* Otherwise, we don't know. */
1816 else if (comp == GT_EXPR || comp == GE_EXPR)
1820 /* If VR is to the right of VAL, return true. */
1821 tst = compare_values (vr->min, val);
1822 if ((comp == GT_EXPR && tst == 1)
1823 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
1824 return boolean_true_node;
1826 /* If VR is to the left of VAL, return false. */
1827 tst = compare_values (vr->max, val);
1828 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
1829 || (comp == GE_EXPR && tst == -1))
1830 return boolean_false_node;
1832 /* Otherwise, we don't know. */
1840 /* Debugging dumps. */
1842 void dump_value_range (FILE *, value_range_t *);
1843 void debug_value_range (value_range_t *);
1844 void dump_all_value_ranges (FILE *);
1845 void debug_all_value_ranges (void);
1846 void dump_vr_equiv (FILE *, bitmap);
1847 void debug_vr_equiv (bitmap);
1850 /* Dump value range VR to FILE. */
1853 dump_value_range (FILE *file, value_range_t *vr)
1856 fprintf (file, "[]");
1857 else if (vr->type == VR_UNDEFINED)
1858 fprintf (file, "UNDEFINED");
1859 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
1861 tree type = TREE_TYPE (vr->min);
1863 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
1865 if (INTEGRAL_TYPE_P (type)
1866 && !TYPE_UNSIGNED (type)
1867 && vr->min == TYPE_MIN_VALUE (type))
1868 fprintf (file, "-INF");
1870 print_generic_expr (file, vr->min, 0);
1872 fprintf (file, ", ");
1874 if (INTEGRAL_TYPE_P (type)
1875 && vr->max == TYPE_MAX_VALUE (type))
1876 fprintf (file, "+INF");
1878 print_generic_expr (file, vr->max, 0);
1880 fprintf (file, "]");
1887 fprintf (file, " EQUIVALENCES: { ");
1889 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
1891 print_generic_expr (file, ssa_name (i), 0);
1892 fprintf (file, " ");
1896 fprintf (file, "} (%u elements)", c);
1899 else if (vr->type == VR_VARYING)
1900 fprintf (file, "VARYING");
1902 fprintf (file, "INVALID RANGE");
1906 /* Dump value range VR to stderr. */
1909 debug_value_range (value_range_t *vr)
1911 dump_value_range (stderr, vr);
1915 /* Dump value ranges of all SSA_NAMEs to FILE. */
1918 dump_all_value_ranges (FILE *file)
1922 for (i = 0; i < num_ssa_names; i++)
1926 print_generic_expr (file, ssa_name (i), 0);
1927 fprintf (file, ": ");
1928 dump_value_range (file, vr_value[i]);
1929 fprintf (file, "\n");
1933 fprintf (file, "\n");
1937 /* Dump all value ranges to stderr. */
1940 debug_all_value_ranges (void)
1942 dump_all_value_ranges (stderr);
1946 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
1947 create a new SSA name N and return the assertion assignment
1948 'V = ASSERT_EXPR <V, V OP W>'. */
1951 build_assert_expr_for (tree cond, tree v)
1955 gcc_assert (TREE_CODE (v) == SSA_NAME);
1956 n = duplicate_ssa_name (v, NULL_TREE);
1958 if (COMPARISON_CLASS_P (cond))
1960 tree a = build (ASSERT_EXPR, TREE_TYPE (v), v, cond);
1961 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, a);
1963 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
1965 /* Given !V, build the assignment N = false. */
1966 tree op0 = TREE_OPERAND (cond, 0);
1967 gcc_assert (op0 == v);
1968 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, boolean_false_node);
1970 else if (TREE_CODE (cond) == SSA_NAME)
1972 /* Given V, build the assignment N = true. */
1973 gcc_assert (v == cond);
1974 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, boolean_true_node);
1979 SSA_NAME_DEF_STMT (n) = assertion;
1981 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
1982 operand of the ASSERT_EXPR. Register the new name and the old one
1983 in the replacement table so that we can fix the SSA web after
1984 adding all the ASSERT_EXPRs. */
1985 register_new_name_mapping (n, v);
1991 /* Return false if EXPR is a predicate expression involving floating
1995 fp_predicate (tree expr)
1997 return (COMPARISON_CLASS_P (expr)
1998 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
2002 /* If the range of values taken by OP can be inferred after STMT executes,
2003 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2004 describes the inferred range. Return true if a range could be
2008 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
2011 *comp_code_p = ERROR_MARK;
2013 /* Do not attempt to infer anything in names that flow through
2015 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
2018 /* Similarly, don't infer anything from statements that may throw
2020 if (tree_could_throw_p (stmt))
2023 if (POINTER_TYPE_P (TREE_TYPE (op)))
2026 unsigned num_uses, num_derefs;
2028 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
2029 if (num_derefs > 0 && flag_delete_null_pointer_checks)
2031 /* We can only assume that a pointer dereference will yield
2032 non-NULL if -fdelete-null-pointer-checks is enabled. */
2033 *val_p = build_int_cst (TREE_TYPE (op), 0);
2034 *comp_code_p = NE_EXPR;
2043 void dump_asserts_for (FILE *, tree);
2044 void debug_asserts_for (tree);
2045 void dump_all_asserts (FILE *);
2046 void debug_all_asserts (void);
2048 /* Dump all the registered assertions for NAME to FILE. */
2051 dump_asserts_for (FILE *file, tree name)
2055 fprintf (file, "Assertions to be inserted for ");
2056 print_generic_expr (file, name, 0);
2057 fprintf (file, "\n");
2059 loc = asserts_for[SSA_NAME_VERSION (name)];
2062 fprintf (file, "\t");
2063 print_generic_expr (file, bsi_stmt (loc->si), 0);
2064 fprintf (file, "\n\tBB #%d", loc->bb->index);
2067 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
2068 loc->e->dest->index);
2069 dump_edge_info (file, loc->e, 0);
2071 fprintf (file, "\n\tPREDICATE: ");
2072 print_generic_expr (file, name, 0);
2073 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
2074 print_generic_expr (file, loc->val, 0);
2075 fprintf (file, "\n\n");
2079 fprintf (file, "\n");
2083 /* Dump all the registered assertions for NAME to stderr. */
2086 debug_asserts_for (tree name)
2088 dump_asserts_for (stderr, name);
2092 /* Dump all the registered assertions for all the names to FILE. */
2095 dump_all_asserts (FILE *file)
2100 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
2101 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2102 dump_asserts_for (file, ssa_name (i));
2103 fprintf (file, "\n");
2107 /* Dump all the registered assertions for all the names to stderr. */
2110 debug_all_asserts (void)
2112 dump_all_asserts (stderr);
2116 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2117 'NAME COMP_CODE VAL' at a location that dominates block BB or
2118 E->DEST, then register this location as a possible insertion point
2119 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2121 BB, E and SI provide the exact insertion point for the new
2122 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2123 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2124 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2125 must not be NULL. */
2128 register_new_assert_for (tree name,
2129 enum tree_code comp_code,
2133 block_stmt_iterator si)
2135 assert_locus_t n, loc, last_loc;
2137 basic_block dest_bb;
2139 #if defined ENABLE_CHECKING
2140 gcc_assert (bb == NULL || e == NULL);
2143 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
2144 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
2147 /* The new assertion A will be inserted at BB or E. We need to
2148 determine if the new location is dominated by a previously
2149 registered location for A. If we are doing an edge insertion,
2150 assume that A will be inserted at E->DEST. Note that this is not
2153 If E is a critical edge, it will be split. But even if E is
2154 split, the new block will dominate the same set of blocks that
2157 The reverse, however, is not true, blocks dominated by E->DEST
2158 will not be dominated by the new block created to split E. So,
2159 if the insertion location is on a critical edge, we will not use
2160 the new location to move another assertion previously registered
2161 at a block dominated by E->DEST. */
2162 dest_bb = (bb) ? bb : e->dest;
2164 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2165 VAL at a block dominating DEST_BB, then we don't need to insert a new
2166 one. Similarly, if the same assertion already exists at a block
2167 dominated by DEST_BB and the new location is not on a critical
2168 edge, then update the existing location for the assertion (i.e.,
2169 move the assertion up in the dominance tree).
2171 Note, this is implemented as a simple linked list because there
2172 should not be more than a handful of assertions registered per
2173 name. If this becomes a performance problem, a table hashed by
2174 COMP_CODE and VAL could be implemented. */
2175 loc = asserts_for[SSA_NAME_VERSION (name)];
2180 if (loc->comp_code == comp_code
2182 || operand_equal_p (loc->val, val, 0)))
2184 /* If the assertion NAME COMP_CODE VAL has already been
2185 registered at a basic block that dominates DEST_BB, then
2186 we don't need to insert the same assertion again. Note
2187 that we don't check strict dominance here to avoid
2188 replicating the same assertion inside the same basic
2189 block more than once (e.g., when a pointer is
2190 dereferenced several times inside a block).
2192 An exception to this rule are edge insertions. If the
2193 new assertion is to be inserted on edge E, then it will
2194 dominate all the other insertions that we may want to
2195 insert in DEST_BB. So, if we are doing an edge
2196 insertion, don't do this dominance check. */
2198 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
2201 /* Otherwise, if E is not a critical edge and DEST_BB
2202 dominates the existing location for the assertion, move
2203 the assertion up in the dominance tree by updating its
2204 location information. */
2205 if ((e == NULL || !EDGE_CRITICAL_P (e))
2206 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
2215 /* Update the last node of the list and move to the next one. */
2220 /* If we didn't find an assertion already registered for
2221 NAME COMP_CODE VAL, add a new one at the end of the list of
2222 assertions associated with NAME. */
2223 n = xmalloc (sizeof (*n));
2227 n->comp_code = comp_code;
2234 asserts_for[SSA_NAME_VERSION (name)] = n;
2236 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
2240 /* Try to register an edge assertion for SSA name NAME on edge E for
2241 the conditional jump pointed to by SI. Return true if an assertion
2242 for NAME could be registered. */
2245 register_edge_assert_for (tree name, edge e, block_stmt_iterator si)
2248 enum tree_code comp_code;
2250 stmt = bsi_stmt (si);
2252 /* Do not attempt to infer anything in names that flow through
2254 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
2257 /* If NAME was not found in the sub-graph reachable from E, then
2258 there's nothing to do. */
2259 if (!TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
2262 /* We found a use of NAME in the sub-graph rooted at E->DEST.
2263 Register an assertion for NAME according to the value that NAME
2265 if (TREE_CODE (stmt) == COND_EXPR)
2267 /* If BB ends in a COND_EXPR then NAME then we should insert
2268 the original predicate on EDGE_TRUE_VALUE and the
2269 opposite predicate on EDGE_FALSE_VALUE. */
2270 tree cond = COND_EXPR_COND (stmt);
2271 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
2273 /* Predicates may be a single SSA name or NAME OP VAL. */
2276 /* If the predicate is a name, it must be NAME, in which
2277 case we create the predicate NAME == true or
2278 NAME == false accordingly. */
2279 comp_code = EQ_EXPR;
2280 val = (is_else_edge) ? boolean_false_node : boolean_true_node;
2284 /* Otherwise, we have a comparison of the form NAME COMP VAL
2285 or VAL COMP NAME. */
2286 if (name == TREE_OPERAND (cond, 1))
2288 /* If the predicate is of the form VAL COMP NAME, flip
2289 COMP around because we need to register NAME as the
2290 first operand in the predicate. */
2291 comp_code = swap_tree_comparison (TREE_CODE (cond));
2292 val = TREE_OPERAND (cond, 0);
2296 /* The comparison is of the form NAME COMP VAL, so the
2297 comparison code remains unchanged. */
2298 comp_code = TREE_CODE (cond);
2299 val = TREE_OPERAND (cond, 1);
2302 /* If we are inserting the assertion on the ELSE edge, we
2303 need to invert the sign comparison. */
2305 comp_code = invert_tree_comparison (comp_code, 0);
2310 /* FIXME. Handle SWITCH_EXPR. */
2314 register_new_assert_for (name, comp_code, val, NULL, e, si);
2319 static bool find_assert_locations (basic_block bb);
2321 /* Determine whether the outgoing edges of BB should receive an
2322 ASSERT_EXPR for each of the operands of BB's last statement. The
2323 last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2325 If any of the sub-graphs rooted at BB have an interesting use of
2326 the predicate operands, an assert location node is added to the
2327 list of assertions for the corresponding operands. */
2330 find_conditional_asserts (basic_block bb)
2333 block_stmt_iterator last_si;
2339 need_assert = false;
2340 last_si = bsi_last (bb);
2341 last = bsi_stmt (last_si);
2343 /* Look for uses of the operands in each of the sub-graphs
2344 rooted at BB. We need to check each of the outgoing edges
2345 separately, so that we know what kind of ASSERT_EXPR to
2347 FOR_EACH_EDGE (e, ei, bb->succs)
2352 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
2353 Otherwise, when we finish traversing each of the sub-graphs, we
2354 won't know whether the variables were found in the sub-graphs or
2355 if they had been found in a block upstream from BB. */
2356 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2357 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2359 /* Traverse the strictly dominated sub-graph rooted at E->DEST
2360 to determine if any of the operands in the conditional
2361 predicate are used. */
2363 need_assert |= find_assert_locations (e->dest);
2365 /* Register the necessary assertions for each operand in the
2366 conditional predicate. */
2367 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2368 need_assert |= register_edge_assert_for (op, e, last_si);
2371 /* Finally, indicate that we have found the operands in the
2373 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2374 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2380 /* Traverse all the statements in block BB looking for statements that
2381 may generate useful assertions for the SSA names in their operand.
2382 If a statement produces a useful assertion A for name N_i, then the
2383 list of assertions already generated for N_i is scanned to
2384 determine if A is actually needed.
2386 If N_i already had the assertion A at a location dominating the
2387 current location, then nothing needs to be done. Otherwise, the
2388 new location for A is recorded instead.
2390 1- For every statement S in BB, all the variables used by S are
2391 added to bitmap FOUND_IN_SUBGRAPH.
2393 2- If statement S uses an operand N in a way that exposes a known
2394 value range for N, then if N was not already generated by an
2395 ASSERT_EXPR, create a new assert location for N. For instance,
2396 if N is a pointer and the statement dereferences it, we can
2397 assume that N is not NULL.
2399 3- COND_EXPRs are a special case of #2. We can derive range
2400 information from the predicate but need to insert different
2401 ASSERT_EXPRs for each of the sub-graphs rooted at the
2402 conditional block. If the last statement of BB is a conditional
2403 expression of the form 'X op Y', then
2405 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
2407 b) If the conditional is the only entry point to the sub-graph
2408 corresponding to the THEN_CLAUSE, recurse into it. On
2409 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
2410 an ASSERT_EXPR is added for the corresponding variable.
2412 c) Repeat step (b) on the ELSE_CLAUSE.
2414 d) Mark X and Y in FOUND_IN_SUBGRAPH.
2423 In this case, an assertion on the THEN clause is useful to
2424 determine that 'a' is always 9 on that edge. However, an assertion
2425 on the ELSE clause would be unnecessary.
2427 4- If BB does not end in a conditional expression, then we recurse
2428 into BB's dominator children.
2430 At the end of the recursive traversal, every SSA name will have a
2431 list of locations where ASSERT_EXPRs should be added. When a new
2432 location for name N is found, it is registered by calling
2433 register_new_assert_for. That function keeps track of all the
2434 registered assertions to prevent adding unnecessary assertions.
2435 For instance, if a pointer P_4 is dereferenced more than once in a
2436 dominator tree, only the location dominating all the dereference of
2437 P_4 will receive an ASSERT_EXPR.
2439 If this function returns true, then it means that there are names
2440 for which we need to generate ASSERT_EXPRs. Those assertions are
2441 inserted by process_assert_insertions.
2443 TODO. Handle SWITCH_EXPR. */
2446 find_assert_locations (basic_block bb)
2448 block_stmt_iterator si;
2453 if (TEST_BIT (blocks_visited, bb->index))
2456 SET_BIT (blocks_visited, bb->index);
2458 need_assert = false;
2460 /* Traverse all PHI nodes in BB marking used operands. */
2461 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
2463 use_operand_p arg_p;
2466 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
2468 tree arg = USE_FROM_PTR (arg_p);
2469 if (TREE_CODE (arg) == SSA_NAME)
2471 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
2472 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
2477 /* Traverse all the statements in BB marking used names and looking
2478 for statements that may infer assertions for their used operands. */
2480 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
2485 stmt = bsi_stmt (si);
2487 /* See if we can derive an assertion for any of STMT's operands. */
2488 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
2491 enum tree_code comp_code;
2493 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
2494 the sub-graph of a conditional block, when we return from
2495 this recursive walk, our parent will use the
2496 FOUND_IN_SUBGRAPH bitset to determine if one of the
2497 operands it was looking for was present in the sub-graph. */
2498 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2500 /* If OP is used only once, namely in this STMT, don't
2501 bother creating an ASSERT_EXPR for it. Such an
2502 ASSERT_EXPR would do nothing but increase compile time.
2503 Experiments show that with this simple check, we can save
2504 more than 20% of ASSERT_EXPRs. */
2505 if (has_single_use (op))
2508 /* If OP is used in such a way that we can infer a value
2509 range for it, and we don't find a previous assertion for
2510 it, create a new assertion location node for OP. */
2511 if (infer_value_range (stmt, op, &comp_code, &value))
2513 register_new_assert_for (op, comp_code, value, bb, NULL, si);
2518 /* Remember the last statement of the block. */
2522 /* If BB's last statement is a conditional expression
2523 involving integer operands, recurse into each of the sub-graphs
2524 rooted at BB to determine if we need to add ASSERT_EXPRs. */
2526 && TREE_CODE (last) == COND_EXPR
2527 && !fp_predicate (COND_EXPR_COND (last))
2528 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
2529 need_assert |= find_conditional_asserts (bb);
2531 /* Recurse into the dominator children of BB. */
2532 for (son = first_dom_son (CDI_DOMINATORS, bb);
2534 son = next_dom_son (CDI_DOMINATORS, son))
2535 need_assert |= find_assert_locations (son);
2541 /* Create an ASSERT_EXPR for NAME and insert it in the location
2542 indicated by LOC. Return true if we made any edge insertions. */
2545 process_assert_insertions_for (tree name, assert_locus_t loc)
2547 /* Build the comparison expression NAME_i COMP_CODE VAL. */
2548 tree stmt, cond, assert_expr;
2552 cond = build (loc->comp_code, boolean_type_node, name, loc->val);
2553 assert_expr = build_assert_expr_for (cond, name);
2557 /* We have been asked to insert the assertion on an edge. This
2558 is used only by COND_EXPR and SWITCH_EXPR assertions. */
2559 #if defined ENABLE_CHECKING
2560 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
2561 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
2564 bsi_insert_on_edge (loc->e, assert_expr);
2568 /* Otherwise, we can insert right after LOC->SI iff the
2569 statement must not be the last statement in the block. */
2570 stmt = bsi_stmt (loc->si);
2571 if (!stmt_ends_bb_p (stmt))
2573 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
2577 /* If STMT must be the last statement in BB, we can only insert new
2578 assertions on the non-abnormal edge out of BB. Note that since
2579 STMT is not control flow, there may only be one non-abnormal edge
2581 FOR_EACH_EDGE (e, ei, loc->bb->succs)
2582 if (!(e->flags & EDGE_ABNORMAL))
2584 bsi_insert_on_edge (e, assert_expr);
2592 /* Process all the insertions registered for every name N_i registered
2593 in NEED_ASSERT_FOR. The list of assertions to be inserted are
2594 found in ASSERTS_FOR[i]. */
2597 process_assert_insertions (void)
2601 bool update_edges_p = false;
2602 int num_asserts = 0;
2604 if (dump_file && (dump_flags & TDF_DETAILS))
2605 dump_all_asserts (dump_file);
2607 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2609 assert_locus_t loc = asserts_for[i];
2614 assert_locus_t next = loc->next;
2615 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
2623 bsi_commit_edge_inserts ();
2625 if (dump_file && (dump_flags & TDF_STATS))
2626 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
2631 /* Traverse the flowgraph looking for conditional jumps to insert range
2632 expressions. These range expressions are meant to provide information
2633 to optimizations that need to reason in terms of value ranges. They
2634 will not be expanded into RTL. For instance, given:
2643 this pass will transform the code into:
2649 x = ASSERT_EXPR <x, x < y>
2654 y = ASSERT_EXPR <y, x <= y>
2658 The idea is that once copy and constant propagation have run, other
2659 optimizations will be able to determine what ranges of values can 'x'
2660 take in different paths of the code, simply by checking the reaching
2661 definition of 'x'. */
2664 insert_range_assertions (void)
2670 found_in_subgraph = sbitmap_alloc (num_ssa_names);
2671 sbitmap_zero (found_in_subgraph);
2673 blocks_visited = sbitmap_alloc (last_basic_block);
2674 sbitmap_zero (blocks_visited);
2676 need_assert_for = BITMAP_ALLOC (NULL);
2677 asserts_for = xmalloc (num_ssa_names * sizeof (assert_locus_t));
2678 memset (asserts_for, 0, num_ssa_names * sizeof (assert_locus_t));
2680 calculate_dominance_info (CDI_DOMINATORS);
2682 update_ssa_p = false;
2683 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2684 if (find_assert_locations (e->dest))
2685 update_ssa_p = true;
2689 process_assert_insertions ();
2690 update_ssa (TODO_update_ssa_no_phi);
2693 if (dump_file && (dump_flags & TDF_DETAILS))
2695 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
2696 dump_function_to_file (current_function_decl, dump_file, dump_flags);
2699 sbitmap_free (found_in_subgraph);
2701 BITMAP_FREE (need_assert_for);
2705 /* Convert range assertion expressions into the implied copies and
2706 copy propagate away the copies. Doing the trivial copy propagation
2707 here avoids the need to run the full copy propagation pass after
2710 FIXME, this will eventually lead to copy propagation removing the
2711 names that had useful range information attached to them. For
2712 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
2713 then N_i will have the range [3, +INF].
2715 However, by converting the assertion into the implied copy
2716 operation N_i = N_j, we will then copy-propagate N_j into the uses
2717 of N_i and lose the range information. We may want to hold on to
2718 ASSERT_EXPRs a little while longer as the ranges could be used in
2719 things like jump threading.
2721 The problem with keeping ASSERT_EXPRs around is that passes after
2722 VRP need to handle them appropriately.
2724 Another approach would be to make the range information a first
2725 class property of the SSA_NAME so that it can be queried from
2726 any pass. This is made somewhat more complex by the need for
2727 multiple ranges to be associated with one SSA_NAME. */
2730 remove_range_assertions (void)
2733 block_stmt_iterator si;
2735 /* Note that the BSI iterator bump happens at the bottom of the
2736 loop and no bump is necessary if we're removing the statement
2737 referenced by the current BSI. */
2739 for (si = bsi_start (bb); !bsi_end_p (si);)
2741 tree stmt = bsi_stmt (si);
2743 if (TREE_CODE (stmt) == MODIFY_EXPR
2744 && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
2746 tree rhs = TREE_OPERAND (stmt, 1);
2747 tree cond = fold (ASSERT_EXPR_COND (rhs));
2748 use_operand_p use_p;
2749 imm_use_iterator iter;
2751 gcc_assert (cond != boolean_false_node);
2752 TREE_OPERAND (stmt, 1) = ASSERT_EXPR_VAR (rhs);
2755 /* The statement is now a copy. Propagate the RHS into
2756 every use of the LHS. */
2757 FOR_EACH_IMM_USE_SAFE (use_p, iter, TREE_OPERAND (stmt, 0))
2759 SET_USE (use_p, ASSERT_EXPR_VAR (rhs));
2760 update_stmt (USE_STMT (use_p));
2763 /* And finally, remove the copy, it is not needed. */
2772 /* Return true if STMT is interesting for VRP. */
2775 stmt_interesting_for_vrp (tree stmt)
2777 if (TREE_CODE (stmt) == PHI_NODE
2778 && is_gimple_reg (PHI_RESULT (stmt))
2779 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
2780 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
2782 else if (TREE_CODE (stmt) == MODIFY_EXPR)
2784 tree lhs = TREE_OPERAND (stmt, 0);
2786 if (TREE_CODE (lhs) == SSA_NAME
2787 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
2788 || POINTER_TYPE_P (TREE_TYPE (lhs)))
2789 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
2792 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
2799 /* Initialize local data structures for VRP. Return true if VRP
2800 is worth running (i.e. if we found any statements that could
2801 benefit from range information). */
2804 vrp_initialize (void)
2808 vr_value = xmalloc (num_ssa_names * sizeof (value_range_t *));
2809 memset (vr_value, 0, num_ssa_names * sizeof (value_range_t *));
2813 block_stmt_iterator si;
2816 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
2818 if (!stmt_interesting_for_vrp (phi))
2820 tree lhs = PHI_RESULT (phi);
2821 set_value_range_to_varying (get_value_range (lhs));
2822 DONT_SIMULATE_AGAIN (phi) = true;
2825 DONT_SIMULATE_AGAIN (phi) = false;
2828 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
2830 tree stmt = bsi_stmt (si);
2832 if (!stmt_interesting_for_vrp (stmt))
2836 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
2837 set_value_range_to_varying (get_value_range (def));
2838 DONT_SIMULATE_AGAIN (stmt) = true;
2842 DONT_SIMULATE_AGAIN (stmt) = false;
2849 /* Visit assignment STMT. If it produces an interesting range, record
2850 the SSA name in *OUTPUT_P. */
2852 static enum ssa_prop_result
2853 vrp_visit_assignment (tree stmt, tree *output_p)
2858 lhs = TREE_OPERAND (stmt, 0);
2859 rhs = TREE_OPERAND (stmt, 1);
2861 /* We only keep track of ranges in integral and pointer types. */
2862 if (TREE_CODE (lhs) == SSA_NAME
2863 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
2864 || POINTER_TYPE_P (TREE_TYPE (lhs))))
2867 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2869 extract_range_from_expr (&new_vr, rhs);
2871 /* If STMT is inside a loop, we may be able to know something
2872 else about the range of LHS by examining scalar evolution
2874 if (cfg_loops && (l = loop_containing_stmt (stmt)))
2875 adjust_range_with_scev (&new_vr, l, stmt, lhs);
2877 if (update_value_range (lhs, &new_vr))
2881 if (dump_file && (dump_flags & TDF_DETAILS))
2883 fprintf (dump_file, "Found new range for ");
2884 print_generic_expr (dump_file, lhs, 0);
2885 fprintf (dump_file, ": ");
2886 dump_value_range (dump_file, &new_vr);
2887 fprintf (dump_file, "\n\n");
2890 if (new_vr.type == VR_VARYING)
2891 return SSA_PROP_VARYING;
2893 return SSA_PROP_INTERESTING;
2896 return SSA_PROP_NOT_INTERESTING;
2899 /* Every other statement produces no useful ranges. */
2900 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
2901 set_value_range_to_varying (get_value_range (def));
2903 return SSA_PROP_VARYING;
2907 /* Compare all the value ranges for names equivalent to VAR with VAL
2908 using comparison code COMP. Return the same value returned by
2909 compare_range_with_value. */
2912 compare_name_with_value (enum tree_code comp, tree var, tree val)
2919 t = retval = NULL_TREE;
2921 /* Get the set of equivalences for VAR. */
2922 e = get_value_range (var)->equiv;
2924 /* Add VAR to its own set of equivalences so that VAR's value range
2925 is processed by this loop (otherwise, we would have to replicate
2926 the body of the loop just to check VAR's value range). */
2927 bitmap_set_bit (e, SSA_NAME_VERSION (var));
2929 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
2931 value_range_t equiv_vr = *(vr_value[i]);
2933 /* If name N_i does not have a valid range, use N_i as its own
2934 range. This allows us to compare against names that may
2935 have N_i in their ranges. */
2936 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
2938 equiv_vr.type = VR_RANGE;
2939 equiv_vr.min = ssa_name (i);
2940 equiv_vr.max = ssa_name (i);
2943 t = compare_range_with_value (comp, &equiv_vr, val);
2946 /* All the ranges should compare the same against VAL. */
2947 gcc_assert (retval == NULL || t == retval);
2952 /* Remove VAR from its own equivalence set. */
2953 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
2958 /* We couldn't find a non-NULL value for the predicate. */
2963 /* Given a comparison code COMP and names N1 and N2, compare all the
2964 ranges equivalent to N1 against all the ranges equivalent to N2
2965 to determine the value of N1 COMP N2. Return the same value
2966 returned by compare_ranges. */
2969 compare_names (enum tree_code comp, tree n1, tree n2)
2973 bitmap_iterator bi1, bi2;
2976 /* Compare the ranges of every name equivalent to N1 against the
2977 ranges of every name equivalent to N2. */
2978 e1 = get_value_range (n1)->equiv;
2979 e2 = get_value_range (n2)->equiv;
2981 /* Add N1 and N2 to their own set of equivalences to avoid
2982 duplicating the body of the loop just to check N1 and N2
2984 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
2985 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
2987 /* If the equivalence sets have a common intersection, then the two
2988 names can be compared without checking their ranges. */
2989 if (bitmap_intersect_p (e1, e2))
2991 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
2992 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
2994 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
2996 : boolean_false_node;
2999 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3000 N2 to their own set of equivalences to avoid duplicating the body
3001 of the loop just to check N1 and N2 ranges. */
3002 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
3004 value_range_t vr1 = *(vr_value[i1]);
3006 /* If the range is VARYING or UNDEFINED, use the name itself. */
3007 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
3009 vr1.type = VR_RANGE;
3010 vr1.min = ssa_name (i1);
3011 vr1.max = ssa_name (i1);
3014 t = retval = NULL_TREE;
3015 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
3017 value_range_t vr2 = *(vr_value[i2]);
3019 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
3021 vr2.type = VR_RANGE;
3022 vr2.min = ssa_name (i2);
3023 vr2.max = ssa_name (i2);
3026 t = compare_ranges (comp, &vr1, &vr2);
3029 /* All the ranges in the equivalent sets should compare
3031 gcc_assert (retval == NULL || t == retval);
3038 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3039 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3044 /* None of the equivalent ranges are useful in computing this
3046 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3047 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3052 /* Given a conditional predicate COND, try to determine if COND yields
3053 true or false based on the value ranges of its operands. Return
3054 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3055 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3056 NULL if the conditional cannot be evaluated at compile time.
3058 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3059 the operands in COND are used when trying to compute its value.
3060 This is only used during final substitution. During propagation,
3061 we only check the range of each variable and not its equivalents. */
3064 vrp_evaluate_conditional (tree cond, bool use_equiv_p)
3066 gcc_assert (TREE_CODE (cond) == SSA_NAME
3067 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
3069 if (TREE_CODE (cond) == SSA_NAME)
3075 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node);
3078 value_range_t *vr = get_value_range (cond);
3079 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node);
3082 /* If COND has a known boolean range, return it. */
3086 /* Otherwise, if COND has a symbolic range of exactly one value,
3088 vr = get_value_range (cond);
3089 if (vr->type == VR_RANGE && vr->min == vr->max)
3094 tree op0 = TREE_OPERAND (cond, 0);
3095 tree op1 = TREE_OPERAND (cond, 1);
3097 /* We only deal with integral and pointer types. */
3098 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
3099 && !POINTER_TYPE_P (TREE_TYPE (op0)))
3104 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
3105 return compare_names (TREE_CODE (cond), op0, op1);
3106 else if (TREE_CODE (op0) == SSA_NAME)
3107 return compare_name_with_value (TREE_CODE (cond), op0, op1);
3108 else if (TREE_CODE (op1) == SSA_NAME)
3109 return compare_name_with_value (
3110 swap_tree_comparison (TREE_CODE (cond)), op1, op0);
3114 value_range_t *vr0, *vr1;
3116 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
3117 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
3120 return compare_ranges (TREE_CODE (cond), vr0, vr1);
3121 else if (vr0 && vr1 == NULL)
3122 return compare_range_with_value (TREE_CODE (cond), vr0, op1);
3123 else if (vr0 == NULL && vr1)
3124 return compare_range_with_value (
3125 swap_tree_comparison (TREE_CODE (cond)), vr1, op0);
3129 /* Anything else cannot be computed statically. */
3134 /* Visit conditional statement STMT. If we can determine which edge
3135 will be taken out of STMT's basic block, record it in
3136 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3137 SSA_PROP_VARYING. */
3139 static enum ssa_prop_result
3140 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
3144 *taken_edge_p = NULL;
3146 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3147 add ASSERT_EXPRs for them. */
3148 if (TREE_CODE (stmt) == SWITCH_EXPR)
3149 return SSA_PROP_VARYING;
3151 cond = COND_EXPR_COND (stmt);
3153 if (dump_file && (dump_flags & TDF_DETAILS))
3158 fprintf (dump_file, "\nVisiting conditional with predicate: ");
3159 print_generic_expr (dump_file, cond, 0);
3160 fprintf (dump_file, "\nWith known ranges\n");
3162 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
3164 fprintf (dump_file, "\t");
3165 print_generic_expr (dump_file, use, 0);
3166 fprintf (dump_file, ": ");
3167 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
3170 fprintf (dump_file, "\n");
3173 /* Compute the value of the predicate COND by checking the known
3174 ranges of each of its operands.
3176 Note that we cannot evaluate all the equivalent ranges here
3177 because those ranges may not yet be final and with the current
3178 propagation strategy, we cannot determine when the value ranges
3179 of the names in the equivalence set have changed.
3181 For instance, given the following code fragment
3185 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3189 Assume that on the first visit to i_14, i_5 has the temporary
3190 range [8, 8] because the second argument to the PHI function is
3191 not yet executable. We derive the range ~[0, 0] for i_14 and the
3192 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3193 the first time, since i_14 is equivalent to the range [8, 8], we
3194 determine that the predicate is always false.
3196 On the next round of propagation, i_13 is determined to be
3197 VARYING, which causes i_5 to drop down to VARYING. So, another
3198 visit to i_14 is scheduled. In this second visit, we compute the
3199 exact same range and equivalence set for i_14, namely ~[0, 0] and
3200 { i_5 }. But we did not have the previous range for i_5
3201 registered, so vrp_visit_assignment thinks that the range for
3202 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3203 is not visited again, which stops propagation from visiting
3204 statements in the THEN clause of that if().
3206 To properly fix this we would need to keep the previous range
3207 value for the names in the equivalence set. This way we would've
3208 discovered that from one visit to the other i_5 changed from
3209 range [8, 8] to VR_VARYING.
3211 However, fixing this apparent limitation may not be worth the
3212 additional checking. Testing on several code bases (GCC, DLV,
3213 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3214 4 more predicates folded in SPEC. */
3215 val = vrp_evaluate_conditional (cond, false);
3217 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
3219 if (dump_file && (dump_flags & TDF_DETAILS))
3221 fprintf (dump_file, "\nPredicate evaluates to: ");
3222 if (val == NULL_TREE)
3223 fprintf (dump_file, "DON'T KNOW\n");
3225 print_generic_stmt (dump_file, val, 0);
3228 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
3232 /* Evaluate statement STMT. If the statement produces a useful range,
3233 return SSA_PROP_INTERESTING and record the SSA name with the
3234 interesting range into *OUTPUT_P.
3236 If STMT is a conditional branch and we can determine its truth
3237 value, the taken edge is recorded in *TAKEN_EDGE_P.
3239 If STMT produces a varying value, return SSA_PROP_VARYING. */
3241 static enum ssa_prop_result
3242 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
3248 if (dump_file && (dump_flags & TDF_DETAILS))
3250 fprintf (dump_file, "\nVisiting statement:\n");
3251 print_generic_stmt (dump_file, stmt, dump_flags);
3252 fprintf (dump_file, "\n");
3255 ann = stmt_ann (stmt);
3256 if (TREE_CODE (stmt) == MODIFY_EXPR
3257 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3258 return vrp_visit_assignment (stmt, output_p);
3259 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3260 return vrp_visit_cond_stmt (stmt, taken_edge_p);
3262 /* All other statements produce nothing of interest for VRP, so mark
3263 their outputs varying and prevent further simulation. */
3264 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3265 set_value_range_to_varying (get_value_range (def));
3267 return SSA_PROP_VARYING;
3271 /* Meet operation for value ranges. Given two value ranges VR0 and
3272 VR1, store in VR0 the result of meeting VR0 and VR1.
3274 The meeting rules are as follows:
3276 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
3278 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
3279 union of VR0 and VR1. */
3282 vrp_meet (value_range_t *vr0, value_range_t *vr1)
3284 if (vr0->type == VR_UNDEFINED)
3286 copy_value_range (vr0, vr1);
3290 if (vr1->type == VR_UNDEFINED)
3292 /* Nothing to do. VR0 already has the resulting range. */
3296 if (vr0->type == VR_VARYING)
3298 /* Nothing to do. VR0 already has the resulting range. */
3302 if (vr1->type == VR_VARYING)
3304 set_value_range_to_varying (vr0);
3308 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
3310 /* If VR0 and VR1 have a non-empty intersection, compute the
3311 union of both ranges. */
3312 if (value_ranges_intersect_p (vr0, vr1))
3317 /* The lower limit of the new range is the minimum of the
3318 two ranges. If they cannot be compared, the result is
3320 cmp = compare_values (vr0->min, vr1->min);
3321 if (cmp == 0 || cmp == 1)
3327 set_value_range_to_varying (vr0);
3331 /* Similarly, the upper limit of the new range is the
3332 maximum of the two ranges. If they cannot be compared,
3333 the result is VARYING. */
3334 cmp = compare_values (vr0->max, vr1->max);
3335 if (cmp == 0 || cmp == -1)
3341 set_value_range_to_varying (vr0);
3345 /* The resulting set of equivalences is the intersection of
3347 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3348 bitmap_and_into (vr0->equiv, vr1->equiv);
3349 else if (vr0->equiv && !vr1->equiv)
3350 bitmap_clear (vr0->equiv);
3352 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
3357 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
3359 /* Two anti-ranges meet only if they are both identical. */
3360 if (compare_values (vr0->min, vr1->min) == 0
3361 && compare_values (vr0->max, vr1->max) == 0
3362 && compare_values (vr0->min, vr0->max) == 0)
3364 /* The resulting set of equivalences is the intersection of
3366 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3367 bitmap_and_into (vr0->equiv, vr1->equiv);
3368 else if (vr0->equiv && !vr1->equiv)
3369 bitmap_clear (vr0->equiv);
3374 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
3376 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
3377 meet only if the ranges have an empty intersection. The
3378 result of the meet operation is the anti-range. */
3379 if (!symbolic_range_p (vr0)
3380 && !symbolic_range_p (vr1)
3381 && !value_ranges_intersect_p (vr0, vr1))
3383 if (vr1->type == VR_ANTI_RANGE)
3384 copy_value_range (vr0, vr1);
3386 /* The resulting set of equivalences is the intersection of
3388 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3389 bitmap_and_into (vr0->equiv, vr1->equiv);
3390 else if (vr0->equiv && !vr1->equiv)
3391 bitmap_clear (vr0->equiv);
3402 /* The two range VR0 and VR1 do not meet. Before giving up and
3403 setting the result to VARYING, see if we can at least derive a
3404 useful anti-range. */
3405 if (!symbolic_range_p (vr0)
3406 && !range_includes_zero_p (vr0)
3407 && !symbolic_range_p (vr1)
3408 && !range_includes_zero_p (vr1))
3409 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
3411 set_value_range_to_varying (vr0);
3415 /* Visit all arguments for PHI node PHI that flow through executable
3416 edges. If a valid value range can be derived from all the incoming
3417 value ranges, set a new range for the LHS of PHI. */
3419 static enum ssa_prop_result
3420 vrp_visit_phi_node (tree phi)
3423 tree lhs = PHI_RESULT (phi);
3424 value_range_t *lhs_vr = get_value_range (lhs);
3425 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3427 copy_value_range (&vr_result, lhs_vr);
3429 if (dump_file && (dump_flags & TDF_DETAILS))
3431 fprintf (dump_file, "\nVisiting PHI node: ");
3432 print_generic_expr (dump_file, phi, dump_flags);
3435 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
3437 edge e = PHI_ARG_EDGE (phi, i);
3439 if (dump_file && (dump_flags & TDF_DETAILS))
3442 "\n Argument #%d (%d -> %d %sexecutable)\n",
3443 i, e->src->index, e->dest->index,
3444 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
3447 if (e->flags & EDGE_EXECUTABLE)
3449 tree arg = PHI_ARG_DEF (phi, i);
3450 value_range_t vr_arg;
3452 if (TREE_CODE (arg) == SSA_NAME)
3453 vr_arg = *(get_value_range (arg));
3456 vr_arg.type = VR_RANGE;
3459 vr_arg.equiv = NULL;
3462 if (dump_file && (dump_flags & TDF_DETAILS))
3464 fprintf (dump_file, "\t");
3465 print_generic_expr (dump_file, arg, dump_flags);
3466 fprintf (dump_file, "\n\tValue: ");
3467 dump_value_range (dump_file, &vr_arg);
3468 fprintf (dump_file, "\n");
3471 vrp_meet (&vr_result, &vr_arg);
3473 if (vr_result.type == VR_VARYING)
3478 if (vr_result.type == VR_VARYING)
3481 /* To prevent infinite iterations in the algorithm, derive ranges
3482 when the new value is slightly bigger or smaller than the
3484 if (lhs_vr->type == VR_RANGE)
3486 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
3488 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
3489 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
3491 /* If the new minimum is smaller or larger than the previous
3492 one, go all the way to -INF. In the first case, to avoid
3493 iterating millions of times to reach -INF, and in the
3494 other case to avoid infinite bouncing between different
3496 if (cmp_min > 0 || cmp_min < 0)
3497 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
3499 /* Similarly, if the new maximum is smaller or larger than
3500 the previous one, go all the way to +INF. */
3501 if (cmp_max < 0 || cmp_max > 0)
3502 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
3504 /* If we ended up with a (-INF, +INF) range, set it to
3506 if (vr_result.min == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))
3507 && vr_result.max == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)))
3512 /* If the new range is different than the previous value, keep
3514 if (update_value_range (lhs, &vr_result))
3515 return SSA_PROP_INTERESTING;
3517 /* Nothing changed, don't add outgoing edges. */
3518 return SSA_PROP_NOT_INTERESTING;
3520 /* No match found. Set the LHS to VARYING. */
3522 set_value_range_to_varying (lhs_vr);
3523 return SSA_PROP_VARYING;
3526 /* Simplify a division or modulo operator to a right shift or
3527 bitwise and if the first operand is unsigned or is greater
3528 than zero and the second operand is an exact power of two. */
3531 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
3534 tree op = TREE_OPERAND (rhs, 0);
3535 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
3537 if (TYPE_UNSIGNED (TREE_TYPE (op)))
3539 val = integer_one_node;
3543 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node);
3546 if (val && integer_onep (val))
3549 tree op0 = TREE_OPERAND (rhs, 0);
3550 tree op1 = TREE_OPERAND (rhs, 1);
3552 if (rhs_code == TRUNC_DIV_EXPR)
3554 t = build_int_cst (NULL_TREE, tree_log2 (op1));
3555 t = build (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
3559 t = build_int_cst (TREE_TYPE (op1), 1);
3560 t = int_const_binop (MINUS_EXPR, op1, t, 0);
3561 t = fold_convert (TREE_TYPE (op0), t);
3562 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
3565 TREE_OPERAND (stmt, 1) = t;
3570 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
3571 ABS_EXPR. If the operand is <= 0, then simplify the
3572 ABS_EXPR into a NEGATE_EXPR. */
3575 simplify_abs_using_ranges (tree stmt, tree rhs)
3578 tree op = TREE_OPERAND (rhs, 0);
3579 tree type = TREE_TYPE (op);
3580 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
3582 if (TYPE_UNSIGNED (type))
3584 val = integer_zero_node;
3588 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node);
3591 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node);
3595 if (integer_zerop (val))
3596 val = integer_one_node;
3597 else if (integer_onep (val))
3598 val = integer_zero_node;
3603 && (integer_onep (val) || integer_zerop (val)))
3607 if (integer_onep (val))
3608 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
3612 TREE_OPERAND (stmt, 1) = t;
3618 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
3619 a known value range VR.
3621 If there is one and only one value which will satisfy the
3622 conditional, then return that value. Else return NULL. */
3625 test_for_singularity (enum tree_code cond_code, tree op0,
3626 tree op1, value_range_t *vr)
3631 /* Extract minimum/maximum values which satisfy the
3632 the conditional as it was written. */
3633 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
3635 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
3638 if (cond_code == LT_EXPR)
3640 tree one = build_int_cst (TREE_TYPE (op0), 1);
3641 max = fold (build (MINUS_EXPR, TREE_TYPE (op0), max, one));
3644 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
3646 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
3649 if (cond_code == GT_EXPR)
3651 tree one = build_int_cst (TREE_TYPE (op0), 1);
3652 max = fold (build (PLUS_EXPR, TREE_TYPE (op0), max, one));
3656 /* Now refine the minimum and maximum values using any
3657 value range information we have for op0. */
3660 if (compare_values (vr->min, min) == -1)
3664 if (compare_values (vr->max, max) == 1)
3669 /* If the new min/max values have converged to a
3670 single value, then there is only one value which
3671 can satisfy the condition, return that value. */
3672 if (min == max && is_gimple_min_invariant (min))
3678 /* Simplify a conditional using a relational operator to an equality
3679 test if the range information indicates only one value can satisfy
3680 the original conditional. */
3683 simplify_cond_using_ranges (tree stmt)
3685 tree cond = COND_EXPR_COND (stmt);
3686 tree op0 = TREE_OPERAND (cond, 0);
3687 tree op1 = TREE_OPERAND (cond, 1);
3688 enum tree_code cond_code = TREE_CODE (cond);
3690 if (cond_code != NE_EXPR
3691 && cond_code != EQ_EXPR
3692 && TREE_CODE (op0) == SSA_NAME
3693 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
3694 && is_gimple_min_invariant (op1))
3696 value_range_t *vr = get_value_range (op0);
3698 /* If we have range information for OP0, then we might be
3699 able to simplify this conditional. */
3700 if (vr->type == VR_RANGE)
3702 tree new = test_for_singularity (cond_code, op0, op1, vr);
3708 fprintf (dump_file, "Simplified relational ");
3709 print_generic_expr (dump_file, cond, 0);
3710 fprintf (dump_file, " into ");
3713 COND_EXPR_COND (stmt)
3714 = build (EQ_EXPR, boolean_type_node, op0, new);
3719 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
3720 fprintf (dump_file, "\n");
3726 /* Try again after inverting the condition. We only deal
3727 with integral types here, so no need to worry about
3728 issues with inverting FP comparisons. */
3729 cond_code = invert_tree_comparison (cond_code, false);
3730 new = test_for_singularity (cond_code, op0, op1, vr);
3736 fprintf (dump_file, "Simplified relational ");
3737 print_generic_expr (dump_file, cond, 0);
3738 fprintf (dump_file, " into ");
3741 COND_EXPR_COND (stmt)
3742 = build (NE_EXPR, boolean_type_node, op0, new);
3747 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
3748 fprintf (dump_file, "\n");
3757 /* Simplify STMT using ranges if possible. */
3760 simplify_stmt_using_ranges (tree stmt)
3762 if (TREE_CODE (stmt) == MODIFY_EXPR)
3764 tree rhs = TREE_OPERAND (stmt, 1);
3765 enum tree_code rhs_code = TREE_CODE (rhs);
3767 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
3768 and BIT_AND_EXPR respectively if the first operand is greater
3769 than zero and the second operand is an exact power of two. */
3770 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
3771 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
3772 && integer_pow2p (TREE_OPERAND (rhs, 1)))
3773 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
3775 /* Transform ABS (X) into X or -X as appropriate. */
3776 if (rhs_code == ABS_EXPR
3777 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
3778 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
3779 simplify_abs_using_ranges (stmt, rhs);
3781 else if (TREE_CODE (stmt) == COND_EXPR
3782 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
3784 simplify_cond_using_ranges (stmt);
3790 /* Traverse all the blocks folding conditionals with known ranges. */
3796 prop_value_t *single_val_range;
3797 bool do_value_subst_p;
3801 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
3802 dump_all_value_ranges (dump_file);
3803 fprintf (dump_file, "\n");
3806 /* We may have ended with ranges that have exactly one value. Those
3807 values can be substituted as any other copy/const propagated
3808 value using substitute_and_fold. */
3809 single_val_range = xmalloc (num_ssa_names * sizeof (*single_val_range));
3810 memset (single_val_range, 0, num_ssa_names * sizeof (*single_val_range));
3812 do_value_subst_p = false;
3813 for (i = 0; i < num_ssa_names; i++)
3815 && vr_value[i]->type == VR_RANGE
3816 && vr_value[i]->min == vr_value[i]->max)
3818 single_val_range[i].value = vr_value[i]->min;
3819 do_value_subst_p = true;
3822 if (!do_value_subst_p)
3824 /* We found no single-valued ranges, don't waste time trying to
3825 do single value substitution in substitute_and_fold. */
3826 free (single_val_range);
3827 single_val_range = NULL;
3830 substitute_and_fold (single_val_range, true);
3832 /* Free allocated memory. */
3833 for (i = 0; i < num_ssa_names; i++)
3836 BITMAP_FREE (vr_value[i]->equiv);
3840 free (single_val_range);
3845 /* Main entry point to VRP (Value Range Propagation). This pass is
3846 loosely based on J. R. C. Patterson, ``Accurate Static Branch
3847 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
3848 Programming Language Design and Implementation, pp. 67-78, 1995.
3849 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
3851 This is essentially an SSA-CCP pass modified to deal with ranges
3852 instead of constants.
3854 While propagating ranges, we may find that two or more SSA name
3855 have equivalent, though distinct ranges. For instance,
3858 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
3860 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
3864 In the code above, pointer p_5 has range [q_2, q_2], but from the
3865 code we can also determine that p_5 cannot be NULL and, if q_2 had
3866 a non-varying range, p_5's range should also be compatible with it.
3868 These equivalences are created by two expressions: ASSERT_EXPR and
3869 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
3870 result of another assertion, then we can use the fact that p_5 and
3871 p_4 are equivalent when evaluating p_5's range.
3873 Together with value ranges, we also propagate these equivalences
3874 between names so that we can take advantage of information from
3875 multiple ranges when doing final replacement. Note that this
3876 equivalency relation is transitive but not symmetric.
3878 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
3879 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
3880 in contexts where that assertion does not hold (e.g., in line 6).
3882 TODO, the main difference between this pass and Patterson's is that
3883 we do not propagate edge probabilities. We only compute whether
3884 edges can be taken or not. That is, instead of having a spectrum
3885 of jump probabilities between 0 and 1, we only deal with 0, 1 and
3886 DON'T KNOW. In the future, it may be worthwhile to propagate
3887 probabilities to aid branch prediction. */
3892 insert_range_assertions ();
3894 cfg_loops = loop_optimizer_init (NULL);
3896 scev_initialize (cfg_loops);
3899 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
3905 loop_optimizer_finalize (cfg_loops, NULL);
3906 current_loops = NULL;
3909 remove_range_assertions ();
3915 return flag_tree_vrp != 0;
3918 struct tree_opt_pass pass_vrp =
3921 gate_vrp, /* gate */
3922 execute_vrp, /* execute */
3925 0, /* static_pass_number */
3926 TV_TREE_VRP, /* tv_id */
3927 PROP_ssa | PROP_alias, /* properties_required */
3928 0, /* properties_provided */
3929 0, /* properties_destroyed */
3930 0, /* todo_flags_start */
3935 | TODO_update_ssa, /* todo_flags_finish */