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 /* Negating an anti-range doesn't really do anything to it. The
1357 new range will also not take on the same range of values
1358 excluded by the original anti-range. */
1359 if (vr0.type == VR_ANTI_RANGE)
1361 copy_value_range (vr, &vr0);
1365 /* NEGATE_EXPR flips the range around. */
1366 min = (vr0.max == TYPE_MAX_VALUE (TREE_TYPE (expr)))
1367 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1368 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1370 max = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1371 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1372 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1374 else if (code == ABS_EXPR
1375 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1377 /* ABS_EXPR may flip the range around, if the original range
1378 included negative values. */
1379 min = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1380 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1381 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1383 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1385 /* If the range was reversed, swap MIN and MAX. */
1386 if (compare_values (min, max) == 1)
1395 /* Otherwise, operate on each end of the range. */
1396 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1397 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1400 cmp = compare_values (min, max);
1401 if (cmp == -2 || cmp == 1)
1403 /* If the new range has its limits swapped around (MIN > MAX),
1404 then the operation caused one of them to wrap around, mark
1405 the new range VARYING. */
1406 set_value_range_to_varying (vr);
1409 set_value_range (vr, vr0.type, min, max, NULL);
1413 /* Extract range information from a comparison expression EXPR based
1414 on the range of its operand and the expression code. */
1417 extract_range_from_comparison (value_range_t *vr, tree expr)
1419 tree val = vrp_evaluate_conditional (expr, false);
1422 /* Since this expression was found on the RHS of an assignment,
1423 its type may be different from _Bool. Convert VAL to EXPR's
1425 val = fold_convert (TREE_TYPE (expr), val);
1426 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
1429 set_value_range_to_varying (vr);
1433 /* Try to compute a useful range out of expression EXPR and store it
1437 extract_range_from_expr (value_range_t *vr, tree expr)
1439 enum tree_code code = TREE_CODE (expr);
1441 if (code == ASSERT_EXPR)
1442 extract_range_from_assert (vr, expr);
1443 else if (code == SSA_NAME)
1444 extract_range_from_ssa_name (vr, expr);
1445 else if (TREE_CODE_CLASS (code) == tcc_binary
1446 || code == TRUTH_ANDIF_EXPR
1447 || code == TRUTH_ORIF_EXPR
1448 || code == TRUTH_AND_EXPR
1449 || code == TRUTH_OR_EXPR
1450 || code == TRUTH_XOR_EXPR)
1451 extract_range_from_binary_expr (vr, expr);
1452 else if (TREE_CODE_CLASS (code) == tcc_unary)
1453 extract_range_from_unary_expr (vr, expr);
1454 else if (TREE_CODE_CLASS (code) == tcc_comparison)
1455 extract_range_from_comparison (vr, expr);
1456 else if (vrp_expr_computes_nonzero (expr))
1457 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1458 else if (is_gimple_min_invariant (expr))
1459 set_value_range (vr, VR_RANGE, expr, expr, NULL);
1461 set_value_range_to_varying (vr);
1464 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1465 would be profitable to adjust VR using scalar evolution information
1466 for VAR. If so, update VR with the new limits. */
1469 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
1472 tree init, step, chrec;
1475 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1476 better opportunities than a regular range, but I'm not sure. */
1477 if (vr->type == VR_ANTI_RANGE)
1480 chrec = analyze_scalar_evolution (loop, var);
1481 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
1484 init = CHREC_LEFT (chrec);
1485 step = CHREC_RIGHT (chrec);
1487 /* If STEP is symbolic, we can't know whether INIT will be the
1488 minimum or maximum value in the range. */
1489 if (!is_gimple_min_invariant (step))
1492 /* Do not adjust ranges when chrec may wrap. */
1493 if (scev_probably_wraps_p (chrec_type (chrec), init, step, stmt,
1494 cfg_loops->parray[CHREC_VARIABLE (chrec)],
1498 if (!POINTER_TYPE_P (TREE_TYPE (init))
1499 && (vr->type == VR_VARYING || vr->type == VR_UNDEFINED))
1501 /* For VARYING or UNDEFINED ranges, just about anything we get
1502 from scalar evolutions should be better. */
1504 set_value_range (vr, VR_RANGE, TYPE_MIN_VALUE (TREE_TYPE (init)),
1507 set_value_range (vr, VR_RANGE, init, TYPE_MAX_VALUE (TREE_TYPE (init)),
1510 else if (vr->type == VR_RANGE)
1517 /* INIT is the maximum value. If INIT is lower than VR->MAX
1518 but no smaller than VR->MIN, set VR->MAX to INIT. */
1519 if (compare_values (init, max) == -1)
1523 /* If we just created an invalid range with the minimum
1524 greater than the maximum, take the minimum all the
1526 if (compare_values (min, max) == 1)
1527 min = TYPE_MIN_VALUE (TREE_TYPE (min));
1532 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
1533 if (compare_values (init, min) == 1)
1537 /* If we just created an invalid range with the minimum
1538 greater than the maximum, take the maximum all the
1540 if (compare_values (min, max) == 1)
1541 max = TYPE_MAX_VALUE (TREE_TYPE (max));
1545 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
1550 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
1552 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
1553 all the values in the ranges.
1555 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
1557 - Return NULL_TREE if it is not always possible to determine the
1558 value of the comparison. */
1562 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1)
1564 /* VARYING or UNDEFINED ranges cannot be compared. */
1565 if (vr0->type == VR_VARYING
1566 || vr0->type == VR_UNDEFINED
1567 || vr1->type == VR_VARYING
1568 || vr1->type == VR_UNDEFINED)
1571 /* Anti-ranges need to be handled separately. */
1572 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
1574 /* If both are anti-ranges, then we cannot compute any
1576 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
1579 /* These comparisons are never statically computable. */
1586 /* Equality can be computed only between a range and an
1587 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
1588 if (vr0->type == VR_RANGE)
1590 /* To simplify processing, make VR0 the anti-range. */
1591 value_range_t *tmp = vr0;
1596 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
1598 if (compare_values (vr0->min, vr1->min) == 0
1599 && compare_values (vr0->max, vr1->max) == 0)
1600 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
1605 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
1606 operands around and change the comparison code. */
1607 if (comp == GT_EXPR || comp == GE_EXPR)
1610 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
1616 if (comp == EQ_EXPR)
1618 /* Equality may only be computed if both ranges represent
1619 exactly one value. */
1620 if (compare_values (vr0->min, vr0->max) == 0
1621 && compare_values (vr1->min, vr1->max) == 0)
1623 int cmp_min = compare_values (vr0->min, vr1->min);
1624 int cmp_max = compare_values (vr0->max, vr1->max);
1625 if (cmp_min == 0 && cmp_max == 0)
1626 return boolean_true_node;
1627 else if (cmp_min != -2 && cmp_max != -2)
1628 return boolean_false_node;
1633 else if (comp == NE_EXPR)
1637 /* If VR0 is completely to the left or completely to the right
1638 of VR1, they are always different. Notice that we need to
1639 make sure that both comparisons yield similar results to
1640 avoid comparing values that cannot be compared at
1642 cmp1 = compare_values (vr0->max, vr1->min);
1643 cmp2 = compare_values (vr0->min, vr1->max);
1644 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
1645 return boolean_true_node;
1647 /* If VR0 and VR1 represent a single value and are identical,
1649 else if (compare_values (vr0->min, vr0->max) == 0
1650 && compare_values (vr1->min, vr1->max) == 0
1651 && compare_values (vr0->min, vr1->min) == 0
1652 && compare_values (vr0->max, vr1->max) == 0)
1653 return boolean_false_node;
1655 /* Otherwise, they may or may not be different. */
1659 else if (comp == LT_EXPR || comp == LE_EXPR)
1663 /* If VR0 is to the left of VR1, return true. */
1664 tst = compare_values (vr0->max, vr1->min);
1665 if ((comp == LT_EXPR && tst == -1)
1666 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
1667 return boolean_true_node;
1669 /* If VR0 is to the right of VR1, return false. */
1670 tst = compare_values (vr0->min, vr1->max);
1671 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
1672 || (comp == LE_EXPR && tst == 1))
1673 return boolean_false_node;
1675 /* Otherwise, we don't know. */
1683 /* Given a value range VR, a value VAL and a comparison code COMP, return
1684 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
1685 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
1686 always returns false. Return NULL_TREE if it is not always
1687 possible to determine the value of the comparison. */
1690 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val)
1692 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
1695 /* Anti-ranges need to be handled separately. */
1696 if (vr->type == VR_ANTI_RANGE)
1698 /* For anti-ranges, the only predicates that we can compute at
1699 compile time are equality and inequality. */
1706 /* ~[VAL, VAL] == VAL is always false. */
1707 if (compare_values (vr->min, val) == 0
1708 && compare_values (vr->max, val) == 0)
1709 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
1714 if (comp == EQ_EXPR)
1716 /* EQ_EXPR may only be computed if VR represents exactly
1718 if (compare_values (vr->min, vr->max) == 0)
1720 int cmp = compare_values (vr->min, val);
1722 return boolean_true_node;
1723 else if (cmp == -1 || cmp == 1 || cmp == 2)
1724 return boolean_false_node;
1726 else if (compare_values (val, vr->min) == -1
1727 || compare_values (vr->max, val) == -1)
1728 return boolean_false_node;
1732 else if (comp == NE_EXPR)
1734 /* If VAL is not inside VR, then they are always different. */
1735 if (compare_values (vr->max, val) == -1
1736 || compare_values (vr->min, val) == 1)
1737 return boolean_true_node;
1739 /* If VR represents exactly one value equal to VAL, then return
1741 if (compare_values (vr->min, vr->max) == 0
1742 && compare_values (vr->min, val) == 0)
1743 return boolean_false_node;
1745 /* Otherwise, they may or may not be different. */
1748 else if (comp == LT_EXPR || comp == LE_EXPR)
1752 /* If VR is to the left of VAL, return true. */
1753 tst = compare_values (vr->max, val);
1754 if ((comp == LT_EXPR && tst == -1)
1755 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
1756 return boolean_true_node;
1758 /* If VR is to the right of VAL, return false. */
1759 tst = compare_values (vr->min, val);
1760 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
1761 || (comp == LE_EXPR && tst == 1))
1762 return boolean_false_node;
1764 /* Otherwise, we don't know. */
1767 else if (comp == GT_EXPR || comp == GE_EXPR)
1771 /* If VR is to the right of VAL, return true. */
1772 tst = compare_values (vr->min, val);
1773 if ((comp == GT_EXPR && tst == 1)
1774 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
1775 return boolean_true_node;
1777 /* If VR is to the left of VAL, return false. */
1778 tst = compare_values (vr->max, val);
1779 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
1780 || (comp == GE_EXPR && tst == -1))
1781 return boolean_false_node;
1783 /* Otherwise, we don't know. */
1791 /* Debugging dumps. */
1793 void dump_value_range (FILE *, value_range_t *);
1794 void debug_value_range (value_range_t *);
1795 void dump_all_value_ranges (FILE *);
1796 void debug_all_value_ranges (void);
1797 void dump_vr_equiv (FILE *, bitmap);
1798 void debug_vr_equiv (bitmap);
1801 /* Dump value range VR to FILE. */
1804 dump_value_range (FILE *file, value_range_t *vr)
1807 fprintf (file, "[]");
1808 else if (vr->type == VR_UNDEFINED)
1809 fprintf (file, "UNDEFINED");
1810 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
1812 tree type = TREE_TYPE (vr->min);
1814 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
1816 if (INTEGRAL_TYPE_P (type)
1817 && !TYPE_UNSIGNED (type)
1818 && vr->min == TYPE_MIN_VALUE (type))
1819 fprintf (file, "-INF");
1821 print_generic_expr (file, vr->min, 0);
1823 fprintf (file, ", ");
1825 if (INTEGRAL_TYPE_P (type)
1826 && vr->max == TYPE_MAX_VALUE (type))
1827 fprintf (file, "+INF");
1829 print_generic_expr (file, vr->max, 0);
1831 fprintf (file, "]");
1838 fprintf (file, " EQUIVALENCES: { ");
1840 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
1842 print_generic_expr (file, ssa_name (i), 0);
1843 fprintf (file, " ");
1847 fprintf (file, "} (%u elements)", c);
1850 else if (vr->type == VR_VARYING)
1851 fprintf (file, "VARYING");
1853 fprintf (file, "INVALID RANGE");
1857 /* Dump value range VR to stderr. */
1860 debug_value_range (value_range_t *vr)
1862 dump_value_range (stderr, vr);
1866 /* Dump value ranges of all SSA_NAMEs to FILE. */
1869 dump_all_value_ranges (FILE *file)
1873 for (i = 0; i < num_ssa_names; i++)
1877 print_generic_expr (file, ssa_name (i), 0);
1878 fprintf (file, ": ");
1879 dump_value_range (file, vr_value[i]);
1880 fprintf (file, "\n");
1884 fprintf (file, "\n");
1888 /* Dump all value ranges to stderr. */
1891 debug_all_value_ranges (void)
1893 dump_all_value_ranges (stderr);
1897 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
1898 create a new SSA name N and return the assertion assignment
1899 'V = ASSERT_EXPR <V, V OP W>'. */
1902 build_assert_expr_for (tree cond, tree v)
1906 gcc_assert (TREE_CODE (v) == SSA_NAME);
1907 n = duplicate_ssa_name (v, NULL_TREE);
1909 if (COMPARISON_CLASS_P (cond))
1911 tree a = build (ASSERT_EXPR, TREE_TYPE (v), v, cond);
1912 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, a);
1914 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
1916 /* Given !V, build the assignment N = false. */
1917 tree op0 = TREE_OPERAND (cond, 0);
1918 gcc_assert (op0 == v);
1919 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, boolean_false_node);
1921 else if (TREE_CODE (cond) == SSA_NAME)
1923 /* Given V, build the assignment N = true. */
1924 gcc_assert (v == cond);
1925 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, boolean_true_node);
1930 SSA_NAME_DEF_STMT (n) = assertion;
1932 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
1933 operand of the ASSERT_EXPR. Register the new name and the old one
1934 in the replacement table so that we can fix the SSA web after
1935 adding all the ASSERT_EXPRs. */
1936 register_new_name_mapping (n, v);
1942 /* Return false if EXPR is a predicate expression involving floating
1946 fp_predicate (tree expr)
1948 return (COMPARISON_CLASS_P (expr)
1949 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
1953 /* If the range of values taken by OP can be inferred after STMT executes,
1954 return the comparison code (COMP_CODE_P) and value (VAL_P) that
1955 describes the inferred range. Return true if a range could be
1959 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
1962 *comp_code_p = ERROR_MARK;
1964 /* Do not attempt to infer anything in names that flow through
1966 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
1969 /* Similarly, don't infer anything from statements that may throw
1971 if (tree_could_throw_p (stmt))
1974 if (POINTER_TYPE_P (TREE_TYPE (op)))
1977 unsigned num_uses, num_derefs;
1979 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
1980 if (num_derefs > 0 && flag_delete_null_pointer_checks)
1982 /* We can only assume that a pointer dereference will yield
1983 non-NULL if -fdelete-null-pointer-checks is enabled. */
1984 *val_p = build_int_cst (TREE_TYPE (op), 0);
1985 *comp_code_p = NE_EXPR;
1994 void dump_asserts_for (FILE *, tree);
1995 void debug_asserts_for (tree);
1996 void dump_all_asserts (FILE *);
1997 void debug_all_asserts (void);
1999 /* Dump all the registered assertions for NAME to FILE. */
2002 dump_asserts_for (FILE *file, tree name)
2006 fprintf (file, "Assertions to be inserted for ");
2007 print_generic_expr (file, name, 0);
2008 fprintf (file, "\n");
2010 loc = asserts_for[SSA_NAME_VERSION (name)];
2013 fprintf (file, "\t");
2014 print_generic_expr (file, bsi_stmt (loc->si), 0);
2015 fprintf (file, "\n\tBB #%d", loc->bb->index);
2018 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
2019 loc->e->dest->index);
2020 dump_edge_info (file, loc->e, 0);
2022 fprintf (file, "\n\tPREDICATE: ");
2023 print_generic_expr (file, name, 0);
2024 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
2025 print_generic_expr (file, loc->val, 0);
2026 fprintf (file, "\n\n");
2030 fprintf (file, "\n");
2034 /* Dump all the registered assertions for NAME to stderr. */
2037 debug_asserts_for (tree name)
2039 dump_asserts_for (stderr, name);
2043 /* Dump all the registered assertions for all the names to FILE. */
2046 dump_all_asserts (FILE *file)
2051 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
2052 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2053 dump_asserts_for (file, ssa_name (i));
2054 fprintf (file, "\n");
2058 /* Dump all the registered assertions for all the names to stderr. */
2061 debug_all_asserts (void)
2063 dump_all_asserts (stderr);
2067 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2068 'NAME COMP_CODE VAL' at a location that dominates block BB or
2069 E->DEST, then register this location as a possible insertion point
2070 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2072 BB, E and SI provide the exact insertion point for the new
2073 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2074 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2075 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2076 must not be NULL. */
2079 register_new_assert_for (tree name,
2080 enum tree_code comp_code,
2084 block_stmt_iterator si)
2086 assert_locus_t n, loc, last_loc;
2088 basic_block dest_bb;
2090 #if defined ENABLE_CHECKING
2091 gcc_assert (bb == NULL || e == NULL);
2094 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
2095 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
2098 /* The new assertion A will be inserted at BB or E. We need to
2099 determine if the new location is dominated by a previously
2100 registered location for A. If we are doing an edge insertion,
2101 assume that A will be inserted at E->DEST. Note that this is not
2104 If E is a critical edge, it will be split. But even if E is
2105 split, the new block will dominate the same set of blocks that
2108 The reverse, however, is not true, blocks dominated by E->DEST
2109 will not be dominated by the new block created to split E. So,
2110 if the insertion location is on a critical edge, we will not use
2111 the new location to move another assertion previously registered
2112 at a block dominated by E->DEST. */
2113 dest_bb = (bb) ? bb : e->dest;
2115 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2116 VAL at a block dominating DEST_BB, then we don't need to insert a new
2117 one. Similarly, if the same assertion already exists at a block
2118 dominated by DEST_BB and the new location is not on a critical
2119 edge, then update the existing location for the assertion (i.e.,
2120 move the assertion up in the dominance tree).
2122 Note, this is implemented as a simple linked list because there
2123 should not be more than a handful of assertions registered per
2124 name. If this becomes a performance problem, a table hashed by
2125 COMP_CODE and VAL could be implemented. */
2126 loc = asserts_for[SSA_NAME_VERSION (name)];
2131 if (loc->comp_code == comp_code
2133 || operand_equal_p (loc->val, val, 0)))
2135 /* If the assertion NAME COMP_CODE VAL has already been
2136 registered at a basic block that dominates DEST_BB, then
2137 we don't need to insert the same assertion again. Note
2138 that we don't check strict dominance here to avoid
2139 replicating the same assertion inside the same basic
2140 block more than once (e.g., when a pointer is
2141 dereferenced several times inside a block).
2143 An exception to this rule are edge insertions. If the
2144 new assertion is to be inserted on edge E, then it will
2145 dominate all the other insertions that we may want to
2146 insert in DEST_BB. So, if we are doing an edge
2147 insertion, don't do this dominance check. */
2149 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
2152 /* Otherwise, if E is not a critical edge and DEST_BB
2153 dominates the existing location for the assertion, move
2154 the assertion up in the dominance tree by updating its
2155 location information. */
2156 if ((e == NULL || !EDGE_CRITICAL_P (e))
2157 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
2166 /* Update the last node of the list and move to the next one. */
2171 /* If we didn't find an assertion already registered for
2172 NAME COMP_CODE VAL, add a new one at the end of the list of
2173 assertions associated with NAME. */
2174 n = xmalloc (sizeof (*n));
2178 n->comp_code = comp_code;
2185 asserts_for[SSA_NAME_VERSION (name)] = n;
2187 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
2191 /* Try to register an edge assertion for SSA name NAME on edge E for
2192 the conditional jump pointed by SI. Return true if an assertion
2193 for NAME could be registered. */
2196 register_edge_assert_for (tree name, edge e, block_stmt_iterator si)
2199 enum tree_code comp_code;
2201 stmt = bsi_stmt (si);
2203 /* Do not attempt to infer anything in names that flow through
2205 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
2208 /* If NAME was not found in the sub-graph reachable from E, then
2209 there's nothing to do. */
2210 if (!TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
2213 /* We found a use of NAME in the sub-graph rooted at E->DEST.
2214 Register an assertion for NAME according to the value that NAME
2216 if (TREE_CODE (stmt) == COND_EXPR)
2218 /* If BB ends in a COND_EXPR then NAME then we should insert
2219 the original predicate on EDGE_TRUE_VALUE and the
2220 opposite predicate on EDGE_FALSE_VALUE. */
2221 tree cond = COND_EXPR_COND (stmt);
2222 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
2224 /* Predicates may be a single SSA name or NAME OP VAL. */
2227 /* If the predicate is a name, it must be NAME, in which
2228 case we create the predicate NAME == true or
2229 NAME == false accordingly. */
2230 comp_code = EQ_EXPR;
2231 val = (is_else_edge) ? boolean_false_node : boolean_true_node;
2235 /* Otherwise, we have a comparison of the form NAME COMP VAL
2236 or VAL COMP NAME. */
2237 if (name == TREE_OPERAND (cond, 1))
2239 /* If the predicate is of the form VAL COMP NAME, flip
2240 COMP around because we need to register NAME as the
2241 first operand in the predicate. */
2242 comp_code = swap_tree_comparison (TREE_CODE (cond));
2243 val = TREE_OPERAND (cond, 0);
2247 /* The comparison is of the form NAME COMP VAL, so the
2248 comparison code remains unchanged. */
2249 comp_code = TREE_CODE (cond);
2250 val = TREE_OPERAND (cond, 1);
2253 /* If we are inserting the assertion on the ELSE edge, we
2254 need to invert the sign comparison. */
2256 comp_code = invert_tree_comparison (comp_code, 0);
2261 /* FIXME. Handle SWITCH_EXPR. */
2265 register_new_assert_for (name, comp_code, val, NULL, e, si);
2270 static bool find_assert_locations (basic_block bb);
2272 /* Determine whether the outgoing edges of BB should receive an
2273 ASSERT_EXPR for each of the operands of BB's last statement. The
2274 last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2276 If any of the sub-graphs rooted at BB have an interesting use of
2277 the predicate operands, an assert location node is added to the
2278 list of assertions for the corresponding operands. */
2281 find_conditional_asserts (basic_block bb)
2284 block_stmt_iterator last_si;
2290 need_assert = false;
2291 last_si = bsi_last (bb);
2292 last = bsi_stmt (last_si);
2294 /* Look for uses of the operands in each of the sub-graphs
2295 rooted at BB. We need to check each of the outgoing edges
2296 separately, so that we know what kind of ASSERT_EXPR to
2298 FOR_EACH_EDGE (e, ei, bb->succs)
2303 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
2304 Otherwise, when we finish traversing each of the sub-graphs, we
2305 won't know whether the variables were found in the sub-graphs or
2306 if they had been found in a block upstream from BB. */
2307 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2308 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2310 /* Traverse the strictly dominated sub-graph rooted at E->DEST
2311 to determine if any of the operands in the conditional
2312 predicate are used. */
2314 need_assert |= find_assert_locations (e->dest);
2316 /* Register the necessary assertions for each operand in the
2317 conditional predicate. */
2318 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2319 need_assert |= register_edge_assert_for (op, e, last_si);
2322 /* Finally, indicate that we have found the operands in the
2324 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2325 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2331 /* Traverse all the statements in block BB looking for statements that
2332 may generate useful assertions for the SSA names in their operand.
2333 If a statement produces a useful assertion A for name N_i, then the
2334 list of assertions already generated for N_i is scanned to
2335 determine if A is actually needed.
2337 If N_i already had the assertion A at a location dominating the
2338 current location, then nothing needs to be done. Otherwise, the
2339 new location for A is recorded instead.
2341 1- For every statement S in BB, all the variables used by S are
2342 added to bitmap FOUND_IN_SUBGRAPH.
2344 2- If statement S uses an operand N in a way that exposes a known
2345 value range for N, then if N was not already generated by an
2346 ASSERT_EXPR, create a new assert location for N. For instance,
2347 if N is a pointer and the statement dereferences it, we can
2348 assume that N is not NULL.
2350 3- COND_EXPRs are a special case of #2. We can derive range
2351 information from the predicate but need to insert different
2352 ASSERT_EXPRs for each of the sub-graphs rooted at the
2353 conditional block. If the last statement of BB is a conditional
2354 expression of the form 'X op Y', then
2356 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
2358 b) If the conditional is the only entry point to the sub-graph
2359 corresponding to the THEN_CLAUSE, recurse into it. On
2360 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
2361 an ASSERT_EXPR is added for the corresponding variable.
2363 c) Repeat step (b) on the ELSE_CLAUSE.
2365 d) Mark X and Y in FOUND_IN_SUBGRAPH.
2374 In this case, an assertion on the THEN clause is useful to
2375 determine that 'a' is always 9 on that edge. However, an assertion
2376 on the ELSE clause would be unnecessary.
2378 4- If BB does not end in a conditional expression, then we recurse
2379 into BB's dominator children.
2381 At the end of the recursive traversal, every SSA name will have a
2382 list of locations where ASSERT_EXPRs should be added. When a new
2383 location for name N is found, it is registered by calling
2384 register_new_assert_for. That function keeps track of all the
2385 registered assertions to prevent adding unnecessary assertions.
2386 For instance, if a pointer P_4 is dereferenced more than once in a
2387 dominator tree, only the location dominating all the dereference of
2388 P_4 will receive an ASSERT_EXPR.
2390 If this function returns true, then it means that there are names
2391 for which we need to generate ASSERT_EXPRs. Those assertions are
2392 inserted by process_assert_insertions.
2394 TODO. Handle SWITCH_EXPR. */
2397 find_assert_locations (basic_block bb)
2399 block_stmt_iterator si;
2404 if (TEST_BIT (blocks_visited, bb->index))
2407 SET_BIT (blocks_visited, bb->index);
2409 need_assert = false;
2411 /* Traverse all PHI nodes in BB marking used operands. */
2412 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
2414 use_operand_p arg_p;
2417 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
2419 tree arg = USE_FROM_PTR (arg_p);
2420 if (TREE_CODE (arg) == SSA_NAME)
2422 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
2423 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
2428 /* Traverse all the statements in BB marking used names and looking
2429 for statements that may infer assertions for their used operands. */
2431 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
2436 stmt = bsi_stmt (si);
2438 /* See if we can derive an assertion for any of STMT's operands. */
2439 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
2442 enum tree_code comp_code;
2444 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
2445 the sub-graph of a conditional block, when we return from
2446 this recursive walk, our parent will use the
2447 FOUND_IN_SUBGRAPH bitset to determine if one of the
2448 operands it was looking for was present in the sub-graph. */
2449 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2451 /* If OP is used only once, namely in this STMT, don't
2452 bother creating an ASSERT_EXPR for it. Such an
2453 ASSERT_EXPR would do nothing but increase compile time.
2454 Experiments show that with this simple check, we can save
2455 more than 20% of ASSERT_EXPRs. */
2456 if (has_single_use (op))
2459 /* If OP is used in such a way that we can infer a value
2460 range for it, and we don't find a previous assertion for
2461 it, create a new assertion location node for OP. */
2462 if (infer_value_range (stmt, op, &comp_code, &value))
2464 register_new_assert_for (op, comp_code, value, bb, NULL, si);
2469 /* Remember the last statement of the block. */
2473 /* If BB's last statement is a conditional expression
2474 involving integer operands, recurse into each of the sub-graphs
2475 rooted at BB to determine if we need to add ASSERT_EXPRs. */
2477 && TREE_CODE (last) == COND_EXPR
2478 && !fp_predicate (COND_EXPR_COND (last))
2479 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
2480 need_assert |= find_conditional_asserts (bb);
2482 /* Recurse into the dominator children of BB. */
2483 for (son = first_dom_son (CDI_DOMINATORS, bb);
2485 son = next_dom_son (CDI_DOMINATORS, son))
2486 need_assert |= find_assert_locations (son);
2492 /* Create an ASSERT_EXPR for NAME and insert it in the location
2493 indicated by LOC. Return true if we made any edge insertions. */
2496 process_assert_insertions_for (tree name, assert_locus_t loc)
2498 /* Build the comparison expression NAME_i COMP_CODE VAL. */
2499 tree stmt, cond, assert_expr;
2503 cond = build (loc->comp_code, boolean_type_node, name, loc->val);
2504 assert_expr = build_assert_expr_for (cond, name);
2508 /* We have been asked to insert the assertion on an edge. This
2509 is used only by COND_EXPR and SWITCH_EXPR assertions. */
2510 #if defined ENABLE_CHECKING
2511 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
2512 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
2515 bsi_insert_on_edge (loc->e, assert_expr);
2519 /* Otherwise, we can insert right after LOC->SI iff the
2520 statement must not be the last statement in the block. */
2521 stmt = bsi_stmt (loc->si);
2522 if (!stmt_ends_bb_p (stmt))
2524 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
2528 /* If STMT must be the last statement in BB, we can only insert new
2529 assertions on the non-abnormal edge out of BB. Note that since
2530 STMT is not control flow, there may only be one non-abnormal edge
2532 FOR_EACH_EDGE (e, ei, loc->bb->succs)
2533 if (!(e->flags & EDGE_ABNORMAL))
2535 bsi_insert_on_edge (e, assert_expr);
2543 /* Process all the insertions registered for every name N_i registered
2544 in NEED_ASSERT_FOR. The list of assertions to be inserted are
2545 found in ASSERTS_FOR[i]. */
2548 process_assert_insertions (void)
2552 bool update_edges_p = false;
2553 int num_asserts = 0;
2555 if (dump_file && (dump_flags & TDF_DETAILS))
2556 dump_all_asserts (dump_file);
2558 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2560 assert_locus_t loc = asserts_for[i];
2565 assert_locus_t next = loc->next;
2566 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
2574 bsi_commit_edge_inserts ();
2576 if (dump_file && (dump_flags & TDF_STATS))
2577 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
2582 /* Traverse the flowgraph looking for conditional jumps to insert range
2583 expressions. These range expressions are meant to provide information
2584 to optimizations that need to reason in terms of value ranges. They
2585 will not be expanded into RTL. For instance, given:
2594 this pass will transform the code into:
2600 x = ASSERT_EXPR <x, x < y>
2605 y = ASSERT_EXPR <y, x <= y>
2609 The idea is that once copy and constant propagation have run, other
2610 optimizations will be able to determine what ranges of values can 'x'
2611 take in different paths of the code, simply by checking the reaching
2612 definition of 'x'. */
2615 insert_range_assertions (void)
2621 found_in_subgraph = sbitmap_alloc (num_ssa_names);
2622 sbitmap_zero (found_in_subgraph);
2624 blocks_visited = sbitmap_alloc (last_basic_block);
2625 sbitmap_zero (blocks_visited);
2627 need_assert_for = BITMAP_ALLOC (NULL);
2628 asserts_for = xmalloc (num_ssa_names * sizeof (assert_locus_t));
2629 memset (asserts_for, 0, num_ssa_names * sizeof (assert_locus_t));
2631 calculate_dominance_info (CDI_DOMINATORS);
2633 update_ssa_p = false;
2634 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2635 if (find_assert_locations (e->dest))
2636 update_ssa_p = true;
2640 process_assert_insertions ();
2641 update_ssa (TODO_update_ssa_no_phi);
2644 if (dump_file && (dump_flags & TDF_DETAILS))
2646 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
2647 dump_function_to_file (current_function_decl, dump_file, dump_flags);
2650 sbitmap_free (found_in_subgraph);
2652 BITMAP_FREE (need_assert_for);
2656 /* Convert range assertion expressions into the implied copies and
2657 copy propagate away the copies. Doing the trivial copy propagation
2658 here avoids the need to run the full copy propagation pass after
2661 FIXME, this will eventually lead to copy propagation removing the
2662 names that had useful range information attached to them. For
2663 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
2664 then N_i will have the range [3, +INF].
2666 However, by converting the assertion into the implied copy
2667 operation N_i = N_j, we will then copy-propagate N_j into the uses
2668 of N_i and lose the range information. We may want to hold on to
2669 ASSERT_EXPRs a little while longer as the ranges could be used in
2670 things like jump threading.
2672 The problem with keeping ASSERT_EXPRs around is that passes after
2673 VRP need to handle them appropriately.
2675 Another approach would be to make the range information a first
2676 class property of the SSA_NAME so that it can be queried from
2677 any pass. This is made somewhat more complex by the need for
2678 multiple ranges to be associated with one SSA_NAME. */
2681 remove_range_assertions (void)
2684 block_stmt_iterator si;
2686 /* Note that the BSI iterator bump happens at the bottom of the
2687 loop and no bump is necessary if we're removing the statement
2688 referenced by the current BSI. */
2690 for (si = bsi_start (bb); !bsi_end_p (si);)
2692 tree stmt = bsi_stmt (si);
2694 if (TREE_CODE (stmt) == MODIFY_EXPR
2695 && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
2697 tree rhs = TREE_OPERAND (stmt, 1);
2698 tree cond = fold (ASSERT_EXPR_COND (rhs));
2699 use_operand_p use_p;
2700 imm_use_iterator iter;
2702 gcc_assert (cond != boolean_false_node);
2703 TREE_OPERAND (stmt, 1) = ASSERT_EXPR_VAR (rhs);
2706 /* The statement is now a copy. Propagate the RHS into
2707 every use of the LHS. */
2708 FOR_EACH_IMM_USE_SAFE (use_p, iter, TREE_OPERAND (stmt, 0))
2710 SET_USE (use_p, ASSERT_EXPR_VAR (rhs));
2711 update_stmt (USE_STMT (use_p));
2714 /* And finally, remove the copy, it is not needed. */
2723 /* Return true if STMT is interesting for VRP. */
2726 stmt_interesting_for_vrp (tree stmt)
2728 if (TREE_CODE (stmt) == PHI_NODE
2729 && is_gimple_reg (PHI_RESULT (stmt))
2730 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
2731 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
2733 else if (TREE_CODE (stmt) == MODIFY_EXPR)
2735 tree lhs = TREE_OPERAND (stmt, 0);
2737 if (TREE_CODE (lhs) == SSA_NAME
2738 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
2739 || POINTER_TYPE_P (TREE_TYPE (lhs)))
2740 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
2743 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
2750 /* Initialize local data structures for VRP. Return true if VRP
2751 is worth running (i.e. if we found any statements that could
2752 benefit from range information). */
2755 vrp_initialize (void)
2759 vr_value = xmalloc (num_ssa_names * sizeof (value_range_t *));
2760 memset (vr_value, 0, num_ssa_names * sizeof (value_range_t *));
2764 block_stmt_iterator si;
2767 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
2769 if (!stmt_interesting_for_vrp (phi))
2771 tree lhs = PHI_RESULT (phi);
2772 set_value_range_to_varying (get_value_range (lhs));
2773 DONT_SIMULATE_AGAIN (phi) = true;
2776 DONT_SIMULATE_AGAIN (phi) = false;
2779 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
2781 tree stmt = bsi_stmt (si);
2783 if (!stmt_interesting_for_vrp (stmt))
2787 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
2788 set_value_range_to_varying (get_value_range (def));
2789 DONT_SIMULATE_AGAIN (stmt) = true;
2793 DONT_SIMULATE_AGAIN (stmt) = false;
2800 /* Visit assignment STMT. If it produces an interesting range, record
2801 the SSA name in *OUTPUT_P. */
2803 static enum ssa_prop_result
2804 vrp_visit_assignment (tree stmt, tree *output_p)
2809 lhs = TREE_OPERAND (stmt, 0);
2810 rhs = TREE_OPERAND (stmt, 1);
2812 /* We only keep track of ranges in integral and pointer types. */
2813 if (TREE_CODE (lhs) == SSA_NAME
2814 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
2815 || POINTER_TYPE_P (TREE_TYPE (lhs))))
2818 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2820 extract_range_from_expr (&new_vr, rhs);
2822 /* If STMT is inside a loop, we may be able to know something
2823 else about the range of LHS by examining scalar evolution
2825 if (cfg_loops && (l = loop_containing_stmt (stmt)))
2826 adjust_range_with_scev (&new_vr, l, stmt, lhs);
2828 if (update_value_range (lhs, &new_vr))
2832 if (dump_file && (dump_flags & TDF_DETAILS))
2834 fprintf (dump_file, "Found new range for ");
2835 print_generic_expr (dump_file, lhs, 0);
2836 fprintf (dump_file, ": ");
2837 dump_value_range (dump_file, &new_vr);
2838 fprintf (dump_file, "\n\n");
2841 if (new_vr.type == VR_VARYING)
2842 return SSA_PROP_VARYING;
2844 return SSA_PROP_INTERESTING;
2847 return SSA_PROP_NOT_INTERESTING;
2850 /* Every other statement produces no useful ranges. */
2851 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
2852 set_value_range_to_varying (get_value_range (def));
2854 return SSA_PROP_VARYING;
2858 /* Compare all the value ranges for names equivalent to VAR with VAL
2859 using comparison code COMP. Return the same value returned by
2860 compare_range_with_value. */
2863 compare_name_with_value (enum tree_code comp, tree var, tree val)
2870 t = retval = NULL_TREE;
2872 /* Get the set of equivalences for VAR. */
2873 e = get_value_range (var)->equiv;
2875 /* Add VAR to its own set of equivalences so that VAR's value range
2876 is processed by this loop (otherwise, we would have to replicate
2877 the body of the loop just to check VAR's value range). */
2878 bitmap_set_bit (e, SSA_NAME_VERSION (var));
2880 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
2882 value_range_t equiv_vr = *(vr_value[i]);
2884 /* If name N_i does not have a valid range, use N_i as its own
2885 range. This allows us to compare against names that may
2886 have N_i in their ranges. */
2887 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
2889 equiv_vr.type = VR_RANGE;
2890 equiv_vr.min = ssa_name (i);
2891 equiv_vr.max = ssa_name (i);
2894 t = compare_range_with_value (comp, &equiv_vr, val);
2897 /* All the ranges should compare the same against VAL. */
2898 gcc_assert (retval == NULL || t == retval);
2903 /* Remove VAR from its own equivalence set. */
2904 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
2909 /* We couldn't find a non-NULL value for the predicate. */
2914 /* Given a comparison code COMP and names N1 and N2, compare all the
2915 ranges equivalent to N1 against all the ranges equivalent to N2
2916 to determine the value of N1 COMP N2. Return the same value
2917 returned by compare_ranges. */
2920 compare_names (enum tree_code comp, tree n1, tree n2)
2924 bitmap_iterator bi1, bi2;
2927 /* Compare the ranges of every name equivalent to N1 against the
2928 ranges of every name equivalent to N2. */
2929 e1 = get_value_range (n1)->equiv;
2930 e2 = get_value_range (n2)->equiv;
2932 /* Add N1 and N2 to their own set of equivalences to avoid
2933 duplicating the body of the loop just to check N1 and N2
2935 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
2936 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
2938 /* If the equivalence sets have a common intersection, then the two
2939 names can be compared without checking their ranges. */
2940 if (bitmap_intersect_p (e1, e2))
2942 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
2943 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
2945 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
2947 : boolean_false_node;
2950 /* Otherwise, compare all the equivalent ranges. First, add N1 and
2951 N2 to their own set of equivalences to avoid duplicating the body
2952 of the loop just to check N1 and N2 ranges. */
2953 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
2955 value_range_t vr1 = *(vr_value[i1]);
2957 /* If the range is VARYING or UNDEFINED, use the name itself. */
2958 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
2960 vr1.type = VR_RANGE;
2961 vr1.min = ssa_name (i1);
2962 vr1.max = ssa_name (i1);
2965 t = retval = NULL_TREE;
2966 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
2968 value_range_t vr2 = *(vr_value[i2]);
2970 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
2972 vr2.type = VR_RANGE;
2973 vr2.min = ssa_name (i2);
2974 vr2.max = ssa_name (i2);
2977 t = compare_ranges (comp, &vr1, &vr2);
2980 /* All the ranges in the equivalent sets should compare
2982 gcc_assert (retval == NULL || t == retval);
2989 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
2990 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
2995 /* None of the equivalent ranges are useful in computing this
2997 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
2998 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3003 /* Given a conditional predicate COND, try to determine if COND yields
3004 true or false based on the value ranges of its operands. Return
3005 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3006 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3007 NULL if the conditional cannot be evaluated at compile time.
3009 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3010 the operands in COND are used when trying to compute its value.
3011 This is only used during final substitution. During propagation,
3012 we only check the range of each variable and not its equivalents. */
3015 vrp_evaluate_conditional (tree cond, bool use_equiv_p)
3017 gcc_assert (TREE_CODE (cond) == SSA_NAME
3018 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
3020 if (TREE_CODE (cond) == SSA_NAME)
3026 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node);
3029 value_range_t *vr = get_value_range (cond);
3030 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node);
3033 /* If COND has a known boolean range, return it. */
3037 /* Otherwise, if COND has a symbolic range of exactly one value,
3039 vr = get_value_range (cond);
3040 if (vr->type == VR_RANGE && vr->min == vr->max)
3045 tree op0 = TREE_OPERAND (cond, 0);
3046 tree op1 = TREE_OPERAND (cond, 1);
3048 /* We only deal with integral and pointer types. */
3049 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
3050 && !POINTER_TYPE_P (TREE_TYPE (op0)))
3055 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
3056 return compare_names (TREE_CODE (cond), op0, op1);
3057 else if (TREE_CODE (op0) == SSA_NAME)
3058 return compare_name_with_value (TREE_CODE (cond), op0, op1);
3059 else if (TREE_CODE (op1) == SSA_NAME)
3060 return compare_name_with_value (
3061 swap_tree_comparison (TREE_CODE (cond)), op1, op0);
3065 value_range_t *vr0, *vr1;
3067 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
3068 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
3071 return compare_ranges (TREE_CODE (cond), vr0, vr1);
3072 else if (vr0 && vr1 == NULL)
3073 return compare_range_with_value (TREE_CODE (cond), vr0, op1);
3074 else if (vr0 == NULL && vr1)
3075 return compare_range_with_value (
3076 swap_tree_comparison (TREE_CODE (cond)), vr1, op0);
3080 /* Anything else cannot be computed statically. */
3085 /* Visit conditional statement STMT. If we can determine which edge
3086 will be taken out of STMT's basic block, record it in
3087 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3088 SSA_PROP_VARYING. */
3090 static enum ssa_prop_result
3091 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
3095 *taken_edge_p = NULL;
3097 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3098 add ASSERT_EXPRs for them. */
3099 if (TREE_CODE (stmt) == SWITCH_EXPR)
3100 return SSA_PROP_VARYING;
3102 cond = COND_EXPR_COND (stmt);
3104 if (dump_file && (dump_flags & TDF_DETAILS))
3109 fprintf (dump_file, "\nVisiting conditional with predicate: ");
3110 print_generic_expr (dump_file, cond, 0);
3111 fprintf (dump_file, "\nWith known ranges\n");
3113 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
3115 fprintf (dump_file, "\t");
3116 print_generic_expr (dump_file, use, 0);
3117 fprintf (dump_file, ": ");
3118 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
3121 fprintf (dump_file, "\n");
3124 /* Compute the value of the predicate COND by checking the known
3125 ranges of each of its operands.
3127 Note that we cannot evaluate all the equivalent ranges here
3128 because those ranges may not yet be final and with the current
3129 propagation strategy, we cannot determine when the value ranges
3130 of the names in the equivalence set have changed.
3132 For instance, given the following code fragment
3136 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3140 Assume that on the first visit to i_14, i_5 has the temporary
3141 range [8, 8] because the second argument to the PHI function is
3142 not yet executable. We derive the range ~[0, 0] for i_14 and the
3143 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3144 the first time, since i_14 is equivalent to the range [8, 8], we
3145 determine that the predicate is always false.
3147 On the next round of propagation, i_13 is determined to be
3148 VARYING, which causes i_5 to drop down to VARYING. So, another
3149 visit to i_14 is scheduled. In this second visit, we compute the
3150 exact same range and equivalence set for i_14, namely ~[0, 0] and
3151 { i_5 }. But we did not have the previous range for i_5
3152 registered, so vrp_visit_assignment thinks that the range for
3153 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3154 is not visited again, which stops propagation from visiting
3155 statements in the THEN clause of that if().
3157 To properly fix this we would need to keep the previous range
3158 value for the names in the equivalence set. This way we would've
3159 discovered that from one visit to the other i_5 changed from
3160 range [8, 8] to VR_VARYING.
3162 However, fixing this apparent limitation may not be worth the
3163 additional checking. Testing on several code bases (GCC, DLV,
3164 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3165 4 more predicates folded in SPEC. */
3166 val = vrp_evaluate_conditional (cond, false);
3168 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
3170 if (dump_file && (dump_flags & TDF_DETAILS))
3172 fprintf (dump_file, "\nPredicate evaluates to: ");
3173 if (val == NULL_TREE)
3174 fprintf (dump_file, "DON'T KNOW\n");
3176 print_generic_stmt (dump_file, val, 0);
3179 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
3183 /* Evaluate statement STMT. If the statement produces a useful range,
3184 return SSA_PROP_INTERESTING and record the SSA name with the
3185 interesting range into *OUTPUT_P.
3187 If STMT is a conditional branch and we can determine its truth
3188 value, the taken edge is recorded in *TAKEN_EDGE_P.
3190 If STMT produces a varying value, return SSA_PROP_VARYING. */
3192 static enum ssa_prop_result
3193 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
3199 if (dump_file && (dump_flags & TDF_DETAILS))
3201 fprintf (dump_file, "\nVisiting statement:\n");
3202 print_generic_stmt (dump_file, stmt, dump_flags);
3203 fprintf (dump_file, "\n");
3206 ann = stmt_ann (stmt);
3207 if (TREE_CODE (stmt) == MODIFY_EXPR
3208 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3209 return vrp_visit_assignment (stmt, output_p);
3210 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3211 return vrp_visit_cond_stmt (stmt, taken_edge_p);
3213 /* All other statements produce nothing of interest for VRP, so mark
3214 their outputs varying and prevent further simulation. */
3215 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3216 set_value_range_to_varying (get_value_range (def));
3218 return SSA_PROP_VARYING;
3222 /* Meet operation for value ranges. Given two value ranges VR0 and
3223 VR1, store in VR0 the result of meeting VR0 and VR1.
3225 The meeting rules are as follows:
3227 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
3229 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
3230 union of VR0 and VR1. */
3233 vrp_meet (value_range_t *vr0, value_range_t *vr1)
3235 if (vr0->type == VR_UNDEFINED)
3237 copy_value_range (vr0, vr1);
3241 if (vr1->type == VR_UNDEFINED)
3243 /* Nothing to do. VR0 already has the resulting range. */
3247 if (vr0->type == VR_VARYING)
3249 /* Nothing to do. VR0 already has the resulting range. */
3253 if (vr1->type == VR_VARYING)
3255 set_value_range_to_varying (vr0);
3259 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
3261 /* If VR0 and VR1 have a non-empty intersection, compute the
3262 union of both ranges. */
3263 if (value_ranges_intersect_p (vr0, vr1))
3268 /* The lower limit of the new range is the minimum of the
3269 two ranges. If they cannot be compared, the result is
3271 cmp = compare_values (vr0->min, vr1->min);
3272 if (cmp == 0 || cmp == 1)
3278 set_value_range_to_varying (vr0);
3282 /* Similarly, the upper limit of the new range is the
3283 maximum of the two ranges. If they cannot be compared,
3284 the result is VARYING. */
3285 cmp = compare_values (vr0->max, vr1->max);
3286 if (cmp == 0 || cmp == -1)
3292 set_value_range_to_varying (vr0);
3296 /* The resulting set of equivalences is the intersection of
3298 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3299 bitmap_and_into (vr0->equiv, vr1->equiv);
3301 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
3306 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
3308 /* Two anti-ranges meet only if they are both identical. */
3309 if (compare_values (vr0->min, vr1->min) == 0
3310 && compare_values (vr0->max, vr1->max) == 0
3311 && compare_values (vr0->min, vr0->max) == 0)
3313 /* The resulting set of equivalences is the intersection of
3315 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3316 bitmap_and_into (vr0->equiv, vr1->equiv);
3321 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
3323 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
3324 meet only if the ranges have an empty intersection. The
3325 result of the meet operation is the anti-range. */
3326 if (!symbolic_range_p (vr0)
3327 && !symbolic_range_p (vr1)
3328 && !value_ranges_intersect_p (vr0, vr1))
3330 if (vr1->type == VR_ANTI_RANGE)
3331 copy_value_range (vr0, vr1);
3342 /* The two range VR0 and VR1 do not meet. Before giving up and
3343 setting the result to VARYING, see if we can at least derive a
3344 useful anti-range. */
3345 if (!symbolic_range_p (vr0)
3346 && !range_includes_zero_p (vr0)
3347 && !symbolic_range_p (vr1)
3348 && !range_includes_zero_p (vr1))
3349 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
3351 set_value_range_to_varying (vr0);
3355 /* Visit all arguments for PHI node PHI that flow through executable
3356 edges. If a valid value range can be derived from all the incoming
3357 value ranges, set a new range for the LHS of PHI. */
3359 static enum ssa_prop_result
3360 vrp_visit_phi_node (tree phi)
3363 tree lhs = PHI_RESULT (phi);
3364 value_range_t *lhs_vr = get_value_range (lhs);
3365 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3367 copy_value_range (&vr_result, lhs_vr);
3369 if (dump_file && (dump_flags & TDF_DETAILS))
3371 fprintf (dump_file, "\nVisiting PHI node: ");
3372 print_generic_expr (dump_file, phi, dump_flags);
3375 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
3377 edge e = PHI_ARG_EDGE (phi, i);
3379 if (dump_file && (dump_flags & TDF_DETAILS))
3382 "\n Argument #%d (%d -> %d %sexecutable)\n",
3383 i, e->src->index, e->dest->index,
3384 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
3387 if (e->flags & EDGE_EXECUTABLE)
3389 tree arg = PHI_ARG_DEF (phi, i);
3390 value_range_t vr_arg;
3392 if (TREE_CODE (arg) == SSA_NAME)
3393 vr_arg = *(get_value_range (arg));
3396 vr_arg.type = VR_RANGE;
3399 vr_arg.equiv = NULL;
3402 if (dump_file && (dump_flags & TDF_DETAILS))
3404 fprintf (dump_file, "\t");
3405 print_generic_expr (dump_file, arg, dump_flags);
3406 fprintf (dump_file, "\n\tValue: ");
3407 dump_value_range (dump_file, &vr_arg);
3408 fprintf (dump_file, "\n");
3411 vrp_meet (&vr_result, &vr_arg);
3413 if (vr_result.type == VR_VARYING)
3418 if (vr_result.type == VR_VARYING)
3421 /* To prevent infinite iterations in the algorithm, derive ranges
3422 when the new value is slightly bigger or smaller than the
3424 if (lhs_vr->type == VR_RANGE)
3426 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
3428 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
3429 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
3431 /* If the new minimum is smaller or larger than the previous
3432 one, go all the way to -INF. In the first case, to avoid
3433 iterating millions of times to reach -INF, and in the
3434 other case to avoid infinite bouncing between different
3436 if (cmp_min > 0 || cmp_min < 0)
3437 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
3439 /* Similarly, if the new maximum is smaller or larger than
3440 the previous one, go all the way to +INF. */
3441 if (cmp_max < 0 || cmp_max > 0)
3442 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
3444 /* If we ended up with a (-INF, +INF) range, set it to
3446 if (vr_result.min == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))
3447 && vr_result.max == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)))
3452 /* If the new range is different than the previous value, keep
3454 if (update_value_range (lhs, &vr_result))
3455 return SSA_PROP_INTERESTING;
3457 /* Nothing changed, don't add outgoing edges. */
3458 return SSA_PROP_NOT_INTERESTING;
3460 /* No match found. Set the LHS to VARYING. */
3462 set_value_range_to_varying (lhs_vr);
3463 return SSA_PROP_VARYING;
3466 /* Simplify a division or modulo operator to a right shift or
3467 bitwise and if the first operand is unsigned or is greater
3468 than zero and the second operand is an exact power of two. */
3471 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
3474 tree op = TREE_OPERAND (rhs, 0);
3475 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
3477 if (TYPE_UNSIGNED (TREE_TYPE (op)))
3479 val = integer_one_node;
3483 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node);
3486 if (val && integer_onep (val))
3489 tree op0 = TREE_OPERAND (rhs, 0);
3490 tree op1 = TREE_OPERAND (rhs, 1);
3492 if (rhs_code == TRUNC_DIV_EXPR)
3494 t = build_int_cst (NULL_TREE, tree_log2 (op1));
3495 t = build (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
3499 t = build_int_cst (TREE_TYPE (op1), 1);
3500 t = int_const_binop (MINUS_EXPR, op1, t, 0);
3501 t = fold_convert (TREE_TYPE (op0), t);
3502 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
3505 TREE_OPERAND (stmt, 1) = t;
3510 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
3511 ABS_EXPR. If the operand is <= 0, then simplify the
3512 ABS_EXPR into a NEGATE_EXPR. */
3515 simplify_abs_using_ranges (tree stmt, tree rhs)
3518 tree op = TREE_OPERAND (rhs, 0);
3519 tree type = TREE_TYPE (op);
3520 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
3522 if (TYPE_UNSIGNED (type))
3524 val = integer_zero_node;
3528 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node);
3531 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node);
3535 if (integer_zerop (val))
3536 val = integer_one_node;
3537 else if (integer_onep (val))
3538 val = integer_zero_node;
3543 && (integer_onep (val) || integer_zerop (val)))
3547 if (integer_onep (val))
3548 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
3552 TREE_OPERAND (stmt, 1) = t;
3558 /* Simplify a conditional using a relational operator to an equality
3559 test if the range information indicates only one value can satisfy
3560 the original conditional. */
3563 simplify_cond_using_ranges (tree stmt)
3565 tree cond = COND_EXPR_COND (stmt);
3566 tree op0 = TREE_OPERAND (cond, 0);
3567 tree op1 = TREE_OPERAND (cond, 1);
3568 enum tree_code cond_code = TREE_CODE (cond);
3570 if (cond_code != NE_EXPR
3571 && cond_code != EQ_EXPR
3572 && TREE_CODE (op0) == SSA_NAME
3573 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
3574 && is_gimple_min_invariant (op1))
3576 value_range_t *vr = get_value_range (op0);
3578 /* If we have range information for OP0, then we might be
3579 able to simplify this conditional. */
3580 if (vr->type == VR_RANGE)
3585 /* Extract minimum/maximum values which satisfy the
3586 the conditional as it was written. */
3587 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
3589 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
3592 if (cond_code == LT_EXPR)
3594 tree one = build_int_cst (TREE_TYPE (op0), 1);
3595 max = fold (build (MINUS_EXPR, TREE_TYPE (op0), max, one));
3598 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
3600 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
3603 if (cond_code == GT_EXPR)
3605 tree one = build_int_cst (TREE_TYPE (op0), 1);
3606 max = fold (build (PLUS_EXPR, TREE_TYPE (op0), max, one));
3610 /* Now refine the minimum and maximum values using any
3611 value range information we have for op0. */
3614 if (compare_values (vr->min, min) == -1)
3618 if (compare_values (vr->max, max) == 1)
3623 /* If the new min/max values have converged to a
3624 single value, then there is only one value which
3625 can satisfy the condition. Rewrite the condition
3626 to test for equality. */
3628 && is_gimple_min_invariant (min))
3630 COND_EXPR_COND (stmt)
3631 = build (EQ_EXPR, boolean_type_node, op0, min);
3639 /* Simplify STMT using ranges if possible. */
3642 simplify_stmt_using_ranges (tree stmt)
3644 if (TREE_CODE (stmt) == MODIFY_EXPR)
3646 tree rhs = TREE_OPERAND (stmt, 1);
3647 enum tree_code rhs_code = TREE_CODE (rhs);
3649 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
3650 and BIT_AND_EXPR respectively if the first operand is greater
3651 than zero and the second operand is an exact power of two. */
3652 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
3653 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
3654 && integer_pow2p (TREE_OPERAND (rhs, 1)))
3655 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
3657 /* Transform ABS (X) into X or -X as appropriate. */
3658 if (rhs_code == ABS_EXPR
3659 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
3660 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
3661 simplify_abs_using_ranges (stmt, rhs);
3663 else if (TREE_CODE (stmt) == COND_EXPR
3664 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
3666 simplify_cond_using_ranges (stmt);
3672 /* Traverse all the blocks folding conditionals with known ranges. */
3678 prop_value_t *single_val_range;
3679 bool do_value_subst_p;
3683 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
3684 dump_all_value_ranges (dump_file);
3685 fprintf (dump_file, "\n");
3688 /* We may have ended with ranges that have exactly one value. Those
3689 values can be substituted as any other copy/const propagated
3690 value using substitute_and_fold. */
3691 single_val_range = xmalloc (num_ssa_names * sizeof (*single_val_range));
3692 memset (single_val_range, 0, num_ssa_names * sizeof (*single_val_range));
3694 do_value_subst_p = false;
3695 for (i = 0; i < num_ssa_names; i++)
3697 && vr_value[i]->type == VR_RANGE
3698 && vr_value[i]->min == vr_value[i]->max)
3700 single_val_range[i].value = vr_value[i]->min;
3701 do_value_subst_p = true;
3704 if (!do_value_subst_p)
3706 /* We found no single-valued ranges, don't waste time trying to
3707 do single value substitution in substitute_and_fold. */
3708 free (single_val_range);
3709 single_val_range = NULL;
3712 substitute_and_fold (single_val_range, true);
3714 /* Free allocated memory. */
3715 for (i = 0; i < num_ssa_names; i++)
3718 BITMAP_FREE (vr_value[i]->equiv);
3722 free (single_val_range);
3727 /* Main entry point to VRP (Value Range Propagation). This pass is
3728 loosely based on J. R. C. Patterson, ``Accurate Static Branch
3729 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
3730 Programming Language Design and Implementation, pp. 67-78, 1995.
3731 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
3733 This is essentially an SSA-CCP pass modified to deal with ranges
3734 instead of constants.
3736 While propagating ranges, we may find that two or more SSA name
3737 have equivalent, though distinct ranges. For instance,
3740 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
3742 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
3746 In the code above, pointer p_5 has range [q_2, q_2], but from the
3747 code we can also determine that p_5 cannot be NULL and, if q_2 had
3748 a non-varying range, p_5's range should also be compatible with it.
3750 These equivalences are created by two expressions: ASSERT_EXPR and
3751 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
3752 result of another assertion, then we can use the fact that p_5 and
3753 p_4 are equivalent when evaluating p_5's range.
3755 Together with value ranges, we also propagate these equivalences
3756 between names so that we can take advantage of information from
3757 multiple ranges when doing final replacement. Note that this
3758 equivalency relation is transitive but not symmetric.
3760 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
3761 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
3762 in contexts where that assertion does not hold (e.g., in line 6).
3764 TODO, the main difference between this pass and Patterson's is that
3765 we do not propagate edge probabilities. We only compute whether
3766 edges can be taken or not. That is, instead of having a spectrum
3767 of jump probabilities between 0 and 1, we only deal with 0, 1 and
3768 DON'T KNOW. In the future, it may be worthwhile to propagate
3769 probabilities to aid branch prediction. */
3774 insert_range_assertions ();
3776 cfg_loops = loop_optimizer_init (NULL);
3778 scev_initialize (cfg_loops);
3781 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
3787 loop_optimizer_finalize (cfg_loops, NULL);
3788 current_loops = NULL;
3791 remove_range_assertions ();
3797 return flag_tree_vrp != 0;
3800 struct tree_opt_pass pass_vrp =
3803 gate_vrp, /* gate */
3804 execute_vrp, /* execute */
3807 0, /* static_pass_number */
3808 TV_TREE_VRP, /* tv_id */
3809 PROP_ssa | PROP_alias, /* properties_required */
3810 0, /* properties_provided */
3811 0, /* properties_destroyed */
3812 0, /* todo_flags_start */
3817 | TODO_update_ssa, /* todo_flags_finish */