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, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, 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 EXPR computes a non-zero value. */
101 expr_computes_nonzero (tree expr)
103 /* Type casts won't change anything, so just strip them. */
106 /* Calling alloca, guarantees that the value is non-NULL. */
107 if (alloca_call_p (expr))
110 /* The address of a non-weak symbol is never NULL, unless the user
111 has requested not to remove NULL pointer checks. */
112 if (flag_delete_null_pointer_checks
113 && TREE_CODE (expr) == ADDR_EXPR
114 && DECL_P (TREE_OPERAND (expr, 0))
115 && !DECL_WEAK (TREE_OPERAND (expr, 0)))
118 /* IOR of any value with a nonzero value will result in a nonzero
120 if (TREE_CODE (expr) == BIT_IOR_EXPR
121 && integer_nonzerop (TREE_OPERAND (expr, 1)))
128 /* Return true if ARG is marked with the nonnull attribute in the
129 current function signature. */
132 nonnull_arg_p (tree arg)
134 tree t, attrs, fntype;
135 unsigned HOST_WIDE_INT arg_num;
137 gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
139 fntype = TREE_TYPE (current_function_decl);
140 attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype));
142 /* If "nonnull" wasn't specified, we know nothing about the argument. */
143 if (attrs == NULL_TREE)
146 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
147 if (TREE_VALUE (attrs) == NULL_TREE)
150 /* Get the position number for ARG in the function signature. */
151 for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl);
153 t = TREE_CHAIN (t), arg_num++)
159 gcc_assert (t == arg);
161 /* Now see if ARG_NUM is mentioned in the nonnull list. */
162 for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
164 if (compare_tree_int (TREE_VALUE (t), arg_num) == 0)
172 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
175 set_value_range (value_range_t *vr, enum value_range_type t, tree min,
176 tree max, bitmap equiv)
178 #if defined ENABLE_CHECKING
179 /* Check the validity of the range. */
180 if (t == VR_RANGE || t == VR_ANTI_RANGE)
184 gcc_assert (min && max);
186 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
187 gcc_assert (min != TYPE_MIN_VALUE (TREE_TYPE (min))
188 || max != TYPE_MAX_VALUE (TREE_TYPE (max)));
190 cmp = compare_values (min, max);
191 gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
194 if (t == VR_UNDEFINED || t == VR_VARYING)
195 gcc_assert (min == NULL_TREE && max == NULL_TREE);
197 if (t == VR_UNDEFINED || t == VR_VARYING)
198 gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
205 /* Since updating the equivalence set involves deep copying the
206 bitmaps, only do it if absolutely necessary. */
207 if (vr->equiv == NULL)
208 vr->equiv = BITMAP_ALLOC (NULL);
210 if (equiv != vr->equiv)
212 if (equiv && !bitmap_empty_p (equiv))
213 bitmap_copy (vr->equiv, equiv);
215 bitmap_clear (vr->equiv);
220 /* Copy value range FROM into value range TO. */
223 copy_value_range (value_range_t *to, value_range_t *from)
225 set_value_range (to, from->type, from->min, from->max, from->equiv);
229 /* Set value range VR to a non-NULL range of type TYPE. */
232 set_value_range_to_nonnull (value_range_t *vr, tree type)
234 tree zero = build_int_cst (type, 0);
235 set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
239 /* Set value range VR to a NULL range of type TYPE. */
242 set_value_range_to_null (value_range_t *vr, tree type)
244 tree zero = build_int_cst (type, 0);
245 set_value_range (vr, VR_RANGE, zero, zero, vr->equiv);
249 /* Set value range VR to VR_VARYING. */
252 set_value_range_to_varying (value_range_t *vr)
254 vr->type = VR_VARYING;
255 vr->min = vr->max = NULL_TREE;
257 bitmap_clear (vr->equiv);
261 /* Set value range VR to VR_UNDEFINED. */
264 set_value_range_to_undefined (value_range_t *vr)
266 vr->type = VR_UNDEFINED;
267 vr->min = vr->max = NULL_TREE;
269 bitmap_clear (vr->equiv);
273 /* Return value range information for VAR. Create an empty range
276 static value_range_t *
277 get_value_range (tree var)
281 unsigned ver = SSA_NAME_VERSION (var);
287 /* Create a default value range. */
288 vr_value[ver] = vr = xmalloc (sizeof (*vr));
289 memset (vr, 0, sizeof (*vr));
291 /* Allocate an equivalence set. */
292 vr->equiv = BITMAP_ALLOC (NULL);
294 /* If VAR is a default definition, the variable can take any value
296 sym = SSA_NAME_VAR (var);
297 if (var == var_ann (sym)->default_def)
299 /* Try to use the "nonnull" attribute to create ~[0, 0]
300 anti-ranges for pointers. Note that this is only valid with
301 default definitions of PARM_DECLs. */
302 if (TREE_CODE (sym) == PARM_DECL
303 && POINTER_TYPE_P (TREE_TYPE (sym))
304 && nonnull_arg_p (sym))
305 set_value_range_to_nonnull (vr, TREE_TYPE (sym));
307 set_value_range_to_varying (vr);
314 /* Update the value range and equivalence set for variable VAR to
315 NEW_VR. Return true if NEW_VR is different from VAR's previous
318 NOTE: This function assumes that NEW_VR is a temporary value range
319 object created for the sole purpose of updating VAR's range. The
320 storage used by the equivalence set from NEW_VR will be freed by
321 this function. Do not call update_value_range when NEW_VR
322 is the range object associated with another SSA name. */
325 update_value_range (tree var, value_range_t *new_vr)
327 value_range_t *old_vr;
330 /* Update the value range, if necessary. */
331 old_vr = get_value_range (var);
332 is_new = old_vr->type != new_vr->type
333 || old_vr->min != new_vr->min
334 || old_vr->max != new_vr->max
335 || (old_vr->equiv == NULL && new_vr->equiv)
336 || (old_vr->equiv && new_vr->equiv == NULL)
337 || (!bitmap_equal_p (old_vr->equiv, new_vr->equiv));
340 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
343 BITMAP_FREE (new_vr->equiv);
344 new_vr->equiv = NULL;
350 /* Add VAR and VAR's equivalence set to EQUIV. */
353 add_equivalence (bitmap equiv, tree var)
355 unsigned ver = SSA_NAME_VERSION (var);
356 value_range_t *vr = vr_value[ver];
358 bitmap_set_bit (equiv, ver);
360 bitmap_ior_into (equiv, vr->equiv);
364 /* Return true if VR is ~[0, 0]. */
367 range_is_nonnull (value_range_t *vr)
369 return vr->type == VR_ANTI_RANGE
370 && integer_zerop (vr->min)
371 && integer_zerop (vr->max);
375 /* Return true if VR is [0, 0]. */
378 range_is_null (value_range_t *vr)
380 return vr->type == VR_RANGE
381 && integer_zerop (vr->min)
382 && integer_zerop (vr->max);
386 /* Return true if value range VR involves at least one symbol. */
389 symbolic_range_p (value_range_t *vr)
391 return (!is_gimple_min_invariant (vr->min)
392 || !is_gimple_min_invariant (vr->max));
396 /* Like expr_computes_nonzero, but this function uses value ranges
400 vrp_expr_computes_nonzero (tree expr)
402 if (expr_computes_nonzero (expr))
405 /* If we have an expression of the form &X->a, then the expression
406 is nonnull if X is nonnull. */
407 if (TREE_CODE (expr) == ADDR_EXPR)
409 tree base = get_base_address (TREE_OPERAND (expr, 0));
411 if (base != NULL_TREE
412 && TREE_CODE (base) == INDIRECT_REF
413 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
415 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
416 if (range_is_nonnull (vr))
425 /* Compare two values VAL1 and VAL2. Return
427 -2 if VAL1 and VAL2 cannot be compared at compile-time,
430 +1 if VAL1 > VAL2, and
433 This is similar to tree_int_cst_compare but supports pointer values
434 and values that cannot be compared at compile time. */
437 compare_values (tree val1, tree val2)
442 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
444 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
445 == POINTER_TYPE_P (TREE_TYPE (val2)));
447 /* Do some limited symbolic comparisons. */
448 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
450 /* We can determine some comparisons against +INF and -INF even
451 if the other value is an expression. */
452 if (val1 == TYPE_MAX_VALUE (TREE_TYPE (val1))
453 && TREE_CODE (val2) == MINUS_EXPR)
455 /* +INF > NAME - CST. */
458 else if (val1 == TYPE_MIN_VALUE (TREE_TYPE (val1))
459 && TREE_CODE (val2) == PLUS_EXPR)
461 /* -INF < NAME + CST. */
464 else if (TREE_CODE (val1) == MINUS_EXPR
465 && val2 == TYPE_MAX_VALUE (TREE_TYPE (val2)))
467 /* NAME - CST < +INF. */
470 else if (TREE_CODE (val1) == PLUS_EXPR
471 && val2 == TYPE_MIN_VALUE (TREE_TYPE (val2)))
473 /* NAME + CST > -INF. */
478 if ((TREE_CODE (val1) == SSA_NAME
479 || TREE_CODE (val1) == PLUS_EXPR
480 || TREE_CODE (val1) == MINUS_EXPR)
481 && (TREE_CODE (val2) == SSA_NAME
482 || TREE_CODE (val2) == PLUS_EXPR
483 || TREE_CODE (val2) == MINUS_EXPR))
487 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
488 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
489 same name, return -2. */
490 if (TREE_CODE (val1) == SSA_NAME)
497 n1 = TREE_OPERAND (val1, 0);
498 c1 = TREE_OPERAND (val1, 1);
501 if (TREE_CODE (val2) == SSA_NAME)
508 n2 = TREE_OPERAND (val2, 0);
509 c2 = TREE_OPERAND (val2, 1);
512 /* Both values must use the same name. */
516 if (TREE_CODE (val1) == SSA_NAME)
518 if (TREE_CODE (val2) == SSA_NAME)
521 else if (TREE_CODE (val2) == PLUS_EXPR)
522 /* NAME < NAME + CST */
524 else if (TREE_CODE (val2) == MINUS_EXPR)
525 /* NAME > NAME - CST */
528 else if (TREE_CODE (val1) == PLUS_EXPR)
530 if (TREE_CODE (val2) == SSA_NAME)
531 /* NAME + CST > NAME */
533 else if (TREE_CODE (val2) == PLUS_EXPR)
534 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
535 return compare_values (c1, c2);
536 else if (TREE_CODE (val2) == MINUS_EXPR)
537 /* NAME + CST1 > NAME - CST2 */
540 else if (TREE_CODE (val1) == MINUS_EXPR)
542 if (TREE_CODE (val2) == SSA_NAME)
543 /* NAME - CST < NAME */
545 else if (TREE_CODE (val2) == PLUS_EXPR)
546 /* NAME - CST1 < NAME + CST2 */
548 else if (TREE_CODE (val2) == MINUS_EXPR)
549 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
550 C1 and C2 are swapped in the call to compare_values. */
551 return compare_values (c2, c1);
557 /* We cannot compare non-constants. */
558 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
561 /* We cannot compare overflowed values. */
562 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
565 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
566 return tree_int_cst_compare (val1, val2);
571 /* First see if VAL1 and VAL2 are not the same. */
572 if (val1 == val2 || operand_equal_p (val1, val2, 0))
575 /* If VAL1 is a lower address than VAL2, return -1. */
576 t = fold_binary (LT_EXPR, boolean_type_node, val1, val2);
577 if (t == boolean_true_node)
580 /* If VAL1 is a higher address than VAL2, return +1. */
581 t = fold_binary (GT_EXPR, boolean_type_node, val1, val2);
582 if (t == boolean_true_node)
585 /* If VAL1 is different than VAL2, return +2. */
586 t = fold_binary (NE_EXPR, boolean_type_node, val1, val2);
587 if (t == boolean_true_node)
595 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
596 0 if VAL is not inside VR,
597 -2 if we cannot tell either way. */
600 value_inside_range (tree val, value_range_t *vr)
604 cmp1 = compare_values (val, vr->min);
605 if (cmp1 == -2 || cmp1 == 2)
608 cmp2 = compare_values (val, vr->max);
609 if (cmp2 == -2 || cmp2 == 2)
612 return (cmp1 == 0 || cmp1 == 1) && (cmp2 == -1 || cmp2 == 0);
616 /* Return true if value ranges VR0 and VR1 have a non-empty
620 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
622 return (value_inside_range (vr1->min, vr0) == 1
623 || value_inside_range (vr1->max, vr0) == 1
624 || value_inside_range (vr0->min, vr1) == 1
625 || value_inside_range (vr0->max, vr1) == 1);
629 /* Return true if VR includes the value zero, false otherwise. */
632 range_includes_zero_p (value_range_t *vr)
636 gcc_assert (vr->type != VR_UNDEFINED
637 && vr->type != VR_VARYING
638 && !symbolic_range_p (vr));
640 zero = build_int_cst (TREE_TYPE (vr->min), 0);
641 return (value_inside_range (zero, vr) == 1);
645 /* Extract value range information from an ASSERT_EXPR EXPR and store
649 extract_range_from_assert (value_range_t *vr_p, tree expr)
651 tree var, cond, limit, min, max, type;
652 value_range_t *var_vr, *limit_vr;
653 enum tree_code cond_code;
655 var = ASSERT_EXPR_VAR (expr);
656 cond = ASSERT_EXPR_COND (expr);
658 gcc_assert (COMPARISON_CLASS_P (cond));
660 /* Find VAR in the ASSERT_EXPR conditional. */
661 if (var == TREE_OPERAND (cond, 0))
663 /* If the predicate is of the form VAR COMP LIMIT, then we just
664 take LIMIT from the RHS and use the same comparison code. */
665 limit = TREE_OPERAND (cond, 1);
666 cond_code = TREE_CODE (cond);
670 /* If the predicate is of the form LIMIT COMP VAR, then we need
671 to flip around the comparison code to create the proper range
673 limit = TREE_OPERAND (cond, 0);
674 cond_code = swap_tree_comparison (TREE_CODE (cond));
677 type = TREE_TYPE (limit);
678 gcc_assert (limit != var);
680 /* For pointer arithmetic, we only keep track of pointer equality
682 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
684 set_value_range_to_varying (vr_p);
688 /* If LIMIT is another SSA name and LIMIT has a range of its own,
689 try to use LIMIT's range to avoid creating symbolic ranges
691 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
693 /* LIMIT's range is only interesting if it has any useful information. */
695 && (limit_vr->type == VR_UNDEFINED
696 || limit_vr->type == VR_VARYING
697 || symbolic_range_p (limit_vr)))
700 /* Special handling for integral types with super-types. Some FEs
701 construct integral types derived from other types and restrict
702 the range of values these new types may take.
704 It may happen that LIMIT is actually smaller than TYPE's minimum
705 value. For instance, the Ada FE is generating code like this
708 D.1480_32 = nam_30 - 300000361;
709 if (D.1480_32 <= 1) goto <L112>; else goto <L52>;
711 D.1480_94 = ASSERT_EXPR <D.1480_32, D.1480_32 <= 1>;
713 All the names are of type types__name_id___XDLU_300000000__399999999
714 which has min == 300000000 and max == 399999999. This means that
715 the ASSERT_EXPR would try to create the range [3000000, 1] which
718 The fact that the type specifies MIN and MAX values does not
719 automatically mean that every variable of that type will always
720 be within that range, so the predicate may well be true at run
721 time. If we had symbolic -INF and +INF values, we could
722 represent this range, but we currently represent -INF and +INF
723 using the type's min and max values.
725 So, the only sensible thing we can do for now is set the
726 resulting range to VR_VARYING. TODO, would having symbolic -INF
727 and +INF values be worth the trouble? */
728 if (TREE_CODE (limit) != SSA_NAME
729 && INTEGRAL_TYPE_P (type)
732 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
734 tree type_min = TYPE_MIN_VALUE (type);
735 int cmp = compare_values (limit, type_min);
737 /* For < or <= comparisons, if LIMIT is smaller than
738 TYPE_MIN, set the range to VR_VARYING. */
739 if (cmp == -1 || cmp == 0)
741 set_value_range_to_varying (vr_p);
745 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
747 tree type_max = TYPE_MIN_VALUE (type);
748 int cmp = compare_values (limit, type_max);
750 /* For > or >= comparisons, if LIMIT is bigger than
751 TYPE_MAX, set the range to VR_VARYING. */
752 if (cmp == 1 || cmp == 0)
754 set_value_range_to_varying (vr_p);
760 /* The new range has the same set of equivalences of VAR's range. */
761 gcc_assert (vr_p->equiv == NULL);
762 vr_p->equiv = BITMAP_ALLOC (NULL);
763 add_equivalence (vr_p->equiv, var);
765 /* Extract a new range based on the asserted comparison for VAR and
766 LIMIT's value range. Notice that if LIMIT has an anti-range, we
767 will only use it for equality comparisons (EQ_EXPR). For any
768 other kind of assertion, we cannot derive a range from LIMIT's
769 anti-range that can be used to describe the new range. For
770 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
771 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
772 no single range for x_2 that could describe LE_EXPR, so we might
773 as well build the range [b_4, +INF] for it. */
774 if (cond_code == EQ_EXPR)
776 enum value_range_type range_type;
780 range_type = limit_vr->type;
786 range_type = VR_RANGE;
791 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
793 /* When asserting the equality VAR == LIMIT and LIMIT is another
794 SSA name, the new range will also inherit the equivalence set
796 if (TREE_CODE (limit) == SSA_NAME)
797 add_equivalence (vr_p->equiv, limit);
799 else if (cond_code == NE_EXPR)
801 /* As described above, when LIMIT's range is an anti-range and
802 this assertion is an inequality (NE_EXPR), then we cannot
803 derive anything from the anti-range. For instance, if
804 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
805 not imply that VAR's range is [0, 0]. So, in the case of
806 anti-ranges, we just assert the inequality using LIMIT and
807 not its anti-range. */
809 || limit_vr->type == VR_ANTI_RANGE)
820 /* If MIN and MAX cover the whole range for their type, then
821 just use the original LIMIT. */
822 if (INTEGRAL_TYPE_P (type)
823 && min == TYPE_MIN_VALUE (type)
824 && max == TYPE_MAX_VALUE (type))
827 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
829 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
831 min = TYPE_MIN_VALUE (type);
833 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
837 /* If LIMIT_VR is of the form [N1, N2], we need to build the
838 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
843 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
844 if (cond_code == LT_EXPR)
846 tree one = build_int_cst (type, 1);
847 max = fold (build (MINUS_EXPR, type, max, one));
850 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
852 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
854 max = TYPE_MAX_VALUE (type);
856 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
860 /* If LIMIT_VR is of the form [N1, N2], we need to build the
861 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
866 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
867 if (cond_code == GT_EXPR)
869 tree one = build_int_cst (type, 1);
870 min = fold (build (PLUS_EXPR, type, min, one));
873 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
878 /* If VAR already had a known range and the two ranges have a
879 non-empty intersection, we can refine the resulting range.
880 Since the assert expression creates an equivalency and at the
881 same time it asserts a predicate, we can take the intersection of
882 the two ranges to get better precision. */
883 var_vr = get_value_range (var);
884 if (var_vr->type == VR_RANGE
885 && vr_p->type == VR_RANGE
886 && value_ranges_intersect_p (var_vr, vr_p))
888 /* Use the larger of the two minimums. */
889 if (compare_values (vr_p->min, var_vr->min) == -1)
894 /* Use the smaller of the two maximums. */
895 if (compare_values (vr_p->max, var_vr->max) == 1)
900 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
905 /* Extract range information from SSA name VAR and store it in VR. If
906 VAR has an interesting range, use it. Otherwise, create the
907 range [VAR, VAR] and return it. This is useful in situations where
908 we may have conditionals testing values of VARYING names. For
915 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
919 extract_range_from_ssa_name (value_range_t *vr, tree var)
921 value_range_t *var_vr = get_value_range (var);
923 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
924 copy_value_range (vr, var_vr);
926 set_value_range (vr, VR_RANGE, var, var, NULL);
928 add_equivalence (vr->equiv, var);
932 /* Wrapper around int_const_binop. If the operation overflows and we
933 are not using wrapping arithmetic, then adjust the result to be
934 -INF or +INF depending on CODE, VAL1 and VAL2. */
937 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
942 return int_const_binop (code, val1, val2, 0);
944 /* If we are not using wrapping arithmetic, operate symbolically
946 res = int_const_binop (code, val1, val2, 0);
948 /* If the operation overflowed but neither VAL1 nor VAL2 are
949 overflown, return -INF or +INF depending on the operation
950 and the combination of signs of the operands. */
951 if (TREE_OVERFLOW (res)
952 && !TREE_OVERFLOW (val1)
953 && !TREE_OVERFLOW (val2))
955 int sgn1 = tree_int_cst_sgn (val1);
956 int sgn2 = tree_int_cst_sgn (val2);
958 /* Notice that we only need to handle the restricted set of
959 operations handled by extract_range_from_binary_expr.
960 Among them, only multiplication, addition and subtraction
961 can yield overflow without overflown operands because we
962 are working with integral types only... except in the
963 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
966 /* For multiplication, the sign of the overflow is given
967 by the comparison of the signs of the operands. */
968 if ((code == MULT_EXPR && sgn1 == sgn2)
969 /* For addition, the operands must be of the same sign
970 to yield an overflow. Its sign is therefore that
971 of one of the operands, for example the first. */
972 || (code == PLUS_EXPR && sgn1 > 0)
973 /* For subtraction, the operands must be of different
974 signs to yield an overflow. Its sign is therefore
975 that of the first operand or the opposite of that
976 of the second operand. */
977 || (code == MINUS_EXPR && sgn1 > 0)
978 /* For division, the only case is -INF / -1 = +INF. */
979 || code == TRUNC_DIV_EXPR
980 || code == FLOOR_DIV_EXPR
981 || code == CEIL_DIV_EXPR
982 || code == EXACT_DIV_EXPR
983 || code == ROUND_DIV_EXPR)
984 return TYPE_MAX_VALUE (TREE_TYPE (res));
986 return TYPE_MIN_VALUE (TREE_TYPE (res));
993 /* Extract range information from a binary expression EXPR based on
994 the ranges of each of its operands and the expression code. */
997 extract_range_from_binary_expr (value_range_t *vr, tree expr)
999 enum tree_code code = TREE_CODE (expr);
1000 tree op0, op1, min, max;
1002 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1003 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1005 /* Not all binary expressions can be applied to ranges in a
1006 meaningful way. Handle only arithmetic operations. */
1007 if (code != PLUS_EXPR
1008 && code != MINUS_EXPR
1009 && code != MULT_EXPR
1010 && code != TRUNC_DIV_EXPR
1011 && code != FLOOR_DIV_EXPR
1012 && code != CEIL_DIV_EXPR
1013 && code != EXACT_DIV_EXPR
1014 && code != ROUND_DIV_EXPR
1017 && code != TRUTH_ANDIF_EXPR
1018 && code != TRUTH_ORIF_EXPR
1019 && code != TRUTH_AND_EXPR
1020 && code != TRUTH_OR_EXPR
1021 && code != TRUTH_XOR_EXPR)
1023 set_value_range_to_varying (vr);
1027 /* Get value ranges for each operand. For constant operands, create
1028 a new value range with the operand to simplify processing. */
1029 op0 = TREE_OPERAND (expr, 0);
1030 if (TREE_CODE (op0) == SSA_NAME)
1031 vr0 = *(get_value_range (op0));
1032 else if (is_gimple_min_invariant (op0))
1033 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1035 set_value_range_to_varying (&vr0);
1037 op1 = TREE_OPERAND (expr, 1);
1038 if (TREE_CODE (op1) == SSA_NAME)
1039 vr1 = *(get_value_range (op1));
1040 else if (is_gimple_min_invariant (op1))
1041 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1043 set_value_range_to_varying (&vr1);
1045 /* If either range is UNDEFINED, so is the result. */
1046 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1048 set_value_range_to_undefined (vr);
1052 /* Refuse to operate on VARYING ranges, ranges of different kinds
1053 and symbolic ranges. TODO, we may be able to derive anti-ranges
1055 if (vr0.type == VR_VARYING
1056 || vr1.type == VR_VARYING
1057 || vr0.type != vr1.type
1058 || symbolic_range_p (&vr0)
1059 || symbolic_range_p (&vr1))
1061 set_value_range_to_varying (vr);
1065 /* Now evaluate the expression to determine the new range. */
1066 if (POINTER_TYPE_P (TREE_TYPE (expr))
1067 || POINTER_TYPE_P (TREE_TYPE (op0))
1068 || POINTER_TYPE_P (TREE_TYPE (op1)))
1070 /* For pointer types, we are really only interested in asserting
1071 whether the expression evaluates to non-NULL. FIXME, we used
1072 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1073 ivopts is generating expressions with pointer multiplication
1075 if (code == PLUS_EXPR)
1077 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1078 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1079 else if (range_is_null (&vr0) && range_is_null (&vr1))
1080 set_value_range_to_null (vr, TREE_TYPE (expr));
1082 set_value_range_to_varying (vr);
1086 /* Subtracting from a pointer, may yield 0, so just drop the
1087 resulting range to varying. */
1088 set_value_range_to_varying (vr);
1094 /* For integer ranges, apply the operation to each end of the
1095 range and see what we end up with. */
1096 if (code == TRUTH_ANDIF_EXPR
1097 || code == TRUTH_ORIF_EXPR
1098 || code == TRUTH_AND_EXPR
1099 || code == TRUTH_OR_EXPR
1100 || code == TRUTH_XOR_EXPR)
1102 /* Boolean expressions cannot be folded with int_const_binop. */
1103 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1104 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1106 else if (code == PLUS_EXPR
1108 || code == MAX_EXPR)
1110 /* For operations that make the resulting range directly
1111 proportional to the original ranges, apply the operation to
1112 the same end of each range. */
1113 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1114 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1116 else if (code == MULT_EXPR
1117 || code == TRUNC_DIV_EXPR
1118 || code == FLOOR_DIV_EXPR
1119 || code == CEIL_DIV_EXPR
1120 || code == EXACT_DIV_EXPR
1121 || code == ROUND_DIV_EXPR)
1126 /* Multiplications and divisions are a bit tricky to handle,
1127 depending on the mix of signs we have in the two ranges, we
1128 need to operate on different values to get the minimum and
1129 maximum values for the new range. One approach is to figure
1130 out all the variations of range combinations and do the
1133 However, this involves several calls to compare_values and it
1134 is pretty convoluted. It's simpler to do the 4 operations
1135 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1136 MAX1) and then figure the smallest and largest values to form
1139 /* Divisions by zero result in a VARYING value. */
1140 if (code != MULT_EXPR && range_includes_zero_p (&vr1))
1142 set_value_range_to_varying (vr);
1146 /* Compute the 4 cross operations. */
1147 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1149 val[1] = (vr1.max != vr1.min)
1150 ? vrp_int_const_binop (code, vr0.min, vr1.max)
1153 val[2] = (vr0.max != vr0.min)
1154 ? vrp_int_const_binop (code, vr0.max, vr1.min)
1157 val[3] = (vr0.min != vr1.min && vr0.max != vr1.max)
1158 ? vrp_int_const_binop (code, vr0.max, vr1.max)
1161 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1165 for (i = 1; i < 4; i++)
1167 if (TREE_OVERFLOW (min) || TREE_OVERFLOW (max))
1172 if (TREE_OVERFLOW (val[i]))
1174 /* If we found an overflowed value, set MIN and MAX
1175 to it so that we set the resulting range to
1181 if (compare_values (val[i], min) == -1)
1184 if (compare_values (val[i], max) == 1)
1189 else if (code == MINUS_EXPR)
1191 /* For MINUS_EXPR, apply the operation to the opposite ends of
1193 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1194 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1199 /* If either MIN or MAX overflowed, then set the resulting range to
1201 if (TREE_OVERFLOW (min) || TREE_OVERFLOW (max))
1203 set_value_range_to_varying (vr);
1207 cmp = compare_values (min, max);
1208 if (cmp == -2 || cmp == 1)
1210 /* If the new range has its limits swapped around (MIN > MAX),
1211 then the operation caused one of them to wrap around, mark
1212 the new range VARYING. */
1213 set_value_range_to_varying (vr);
1216 set_value_range (vr, vr0.type, min, max, NULL);
1220 /* Extract range information from a unary expression EXPR based on
1221 the range of its operand and the expression code. */
1224 extract_range_from_unary_expr (value_range_t *vr, tree expr)
1226 enum tree_code code = TREE_CODE (expr);
1229 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1231 /* Refuse to operate on certain unary expressions for which we
1232 cannot easily determine a resulting range. */
1233 if (code == FIX_TRUNC_EXPR
1234 || code == FIX_CEIL_EXPR
1235 || code == FIX_FLOOR_EXPR
1236 || code == FIX_ROUND_EXPR
1237 || code == FLOAT_EXPR
1238 || code == BIT_NOT_EXPR
1239 || code == NON_LVALUE_EXPR
1240 || code == CONJ_EXPR)
1242 set_value_range_to_varying (vr);
1246 /* Get value ranges for the operand. For constant operands, create
1247 a new value range with the operand to simplify processing. */
1248 op0 = TREE_OPERAND (expr, 0);
1249 if (TREE_CODE (op0) == SSA_NAME)
1250 vr0 = *(get_value_range (op0));
1251 else if (is_gimple_min_invariant (op0))
1252 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1254 set_value_range_to_varying (&vr0);
1256 /* If VR0 is UNDEFINED, so is the result. */
1257 if (vr0.type == VR_UNDEFINED)
1259 set_value_range_to_undefined (vr);
1263 /* Refuse to operate on varying and symbolic ranges. Also, if the
1264 operand is neither a pointer nor an integral type, set the
1265 resulting range to VARYING. TODO, in some cases we may be able
1266 to derive anti-ranges (like non-zero values). */
1267 if (vr0.type == VR_VARYING
1268 || (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
1269 && !POINTER_TYPE_P (TREE_TYPE (op0)))
1270 || symbolic_range_p (&vr0))
1272 set_value_range_to_varying (vr);
1276 /* If the expression involves pointers, we are only interested in
1277 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1278 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
1280 if (range_is_nonnull (&vr0) || expr_computes_nonzero (expr))
1281 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1282 else if (range_is_null (&vr0))
1283 set_value_range_to_null (vr, TREE_TYPE (expr));
1285 set_value_range_to_varying (vr);
1290 /* Handle unary expressions on integer ranges. */
1291 if (code == NOP_EXPR || code == CONVERT_EXPR)
1293 tree inner_type = TREE_TYPE (op0);
1294 tree outer_type = TREE_TYPE (expr);
1296 /* If VR0 represents a simple range, then try to convert
1297 the min and max values for the range to the same type
1298 as OUTER_TYPE. If the results compare equal to VR0's
1299 min and max values and the new min is still less than
1300 or equal to the new max, then we can safely use the newly
1301 computed range for EXPR. This allows us to compute
1302 accurate ranges through many casts. */
1303 if (vr0.type == VR_RANGE)
1305 tree new_min, new_max;
1307 /* Convert VR0's min/max to OUTER_TYPE. */
1308 new_min = fold_convert (outer_type, vr0.min);
1309 new_max = fold_convert (outer_type, vr0.max);
1311 /* Verify the new min/max values are gimple values and
1312 that they compare equal to VR0's min/max values. */
1313 if (is_gimple_val (new_min)
1314 && is_gimple_val (new_max)
1315 && tree_int_cst_equal (new_min, vr0.min)
1316 && tree_int_cst_equal (new_max, vr0.max)
1317 && compare_values (new_min, new_max) <= 0
1318 && compare_values (new_min, new_max) >= -2)
1320 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
1325 /* When converting types of different sizes, set the result to
1326 VARYING. Things like sign extensions and precision loss may
1327 change the range. For instance, if x_3 is of type 'long long
1328 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1329 is impossible to know at compile time whether y_5 will be
1331 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
1332 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
1334 set_value_range_to_varying (vr);
1339 /* Apply the operation to each end of the range and see what we end
1341 if (code == NEGATE_EXPR
1342 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1344 /* Negating an anti-range doesn't really do anything to it. The
1345 new range will also not take on the same range of values
1346 excluded by the original anti-range. */
1347 if (vr0.type == VR_ANTI_RANGE)
1349 copy_value_range (vr, &vr0);
1353 /* NEGATE_EXPR flips the range around. */
1354 min = (vr0.max == TYPE_MAX_VALUE (TREE_TYPE (expr)))
1355 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1356 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1358 max = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1359 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1360 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1362 else if (code == ABS_EXPR
1363 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1365 /* ABS_EXPR may flip the range around, if the original range
1366 included negative values. */
1367 min = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1368 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1369 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1371 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1373 /* If the range was reversed, swap MIN and MAX. */
1374 if (compare_values (min, max) == 1)
1383 /* Otherwise, operate on each end of the range. */
1384 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1385 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1388 cmp = compare_values (min, max);
1389 if (cmp == -2 || cmp == 1)
1391 /* If the new range has its limits swapped around (MIN > MAX),
1392 then the operation caused one of them to wrap around, mark
1393 the new range VARYING. */
1394 set_value_range_to_varying (vr);
1397 set_value_range (vr, vr0.type, min, max, NULL);
1401 /* Extract range information from a comparison expression EXPR based
1402 on the range of its operand and the expression code. */
1405 extract_range_from_comparison (value_range_t *vr, tree expr)
1407 tree val = vrp_evaluate_conditional (expr, false);
1410 /* Since this expression was found on the RHS of an assignment,
1411 its type may be different from _Bool. Convert VAL to EXPR's
1413 val = fold_convert (TREE_TYPE (expr), val);
1414 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
1417 set_value_range_to_varying (vr);
1421 /* Try to compute a useful range out of expression EXPR and store it
1425 extract_range_from_expr (value_range_t *vr, tree expr)
1427 enum tree_code code = TREE_CODE (expr);
1429 if (code == ASSERT_EXPR)
1430 extract_range_from_assert (vr, expr);
1431 else if (code == SSA_NAME)
1432 extract_range_from_ssa_name (vr, expr);
1433 else if (TREE_CODE_CLASS (code) == tcc_binary
1434 || code == TRUTH_ANDIF_EXPR
1435 || code == TRUTH_ORIF_EXPR
1436 || code == TRUTH_AND_EXPR
1437 || code == TRUTH_OR_EXPR
1438 || code == TRUTH_XOR_EXPR)
1439 extract_range_from_binary_expr (vr, expr);
1440 else if (TREE_CODE_CLASS (code) == tcc_unary)
1441 extract_range_from_unary_expr (vr, expr);
1442 else if (TREE_CODE_CLASS (code) == tcc_comparison)
1443 extract_range_from_comparison (vr, expr);
1444 else if (vrp_expr_computes_nonzero (expr))
1445 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1446 else if (is_gimple_min_invariant (expr))
1447 set_value_range (vr, VR_RANGE, expr, expr, NULL);
1449 set_value_range_to_varying (vr);
1452 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1453 would be profitable to adjust VR using scalar evolution information
1454 for VAR. If so, update VR with the new limits. */
1457 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
1460 tree init, step, chrec;
1463 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1464 better opportunities than a regular range, but I'm not sure. */
1465 if (vr->type == VR_ANTI_RANGE)
1468 chrec = analyze_scalar_evolution (loop, var);
1469 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
1472 init = CHREC_LEFT (chrec);
1473 step = CHREC_RIGHT (chrec);
1475 /* If STEP is symbolic, we can't know whether INIT will be the
1476 minimum or maximum value in the range. */
1477 if (!is_gimple_min_invariant (step))
1480 /* Do not adjust ranges when chrec may wrap. */
1481 if (scev_probably_wraps_p (chrec_type (chrec), init, step, stmt,
1482 cfg_loops->parray[CHREC_VARIABLE (chrec)],
1486 if (!POINTER_TYPE_P (TREE_TYPE (init))
1487 && (vr->type == VR_VARYING || vr->type == VR_UNDEFINED))
1489 /* For VARYING or UNDEFINED ranges, just about anything we get
1490 from scalar evolutions should be better. */
1492 set_value_range (vr, VR_RANGE, TYPE_MIN_VALUE (TREE_TYPE (init)),
1495 set_value_range (vr, VR_RANGE, init, TYPE_MAX_VALUE (TREE_TYPE (init)),
1498 else if (vr->type == VR_RANGE)
1505 /* INIT is the maximum value. If INIT is lower than VR->MAX
1506 but no smaller than VR->MIN, set VR->MAX to INIT. */
1507 if (compare_values (init, max) == -1)
1511 /* If we just created an invalid range with the minimum
1512 greater than the maximum, take the minimum all the
1514 if (compare_values (min, max) == 1)
1515 min = TYPE_MIN_VALUE (TREE_TYPE (min));
1520 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
1521 if (compare_values (init, min) == 1)
1525 /* If we just created an invalid range with the minimum
1526 greater than the maximum, take the maximum all the
1528 if (compare_values (min, max) == 1)
1529 max = TYPE_MAX_VALUE (TREE_TYPE (max));
1533 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
1538 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
1540 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
1541 all the values in the ranges.
1543 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
1545 - Return NULL_TREE if it is not always possible to determine the
1546 value of the comparison. */
1550 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1)
1552 /* VARYING or UNDEFINED ranges cannot be compared. */
1553 if (vr0->type == VR_VARYING
1554 || vr0->type == VR_UNDEFINED
1555 || vr1->type == VR_VARYING
1556 || vr1->type == VR_UNDEFINED)
1559 /* Anti-ranges need to be handled separately. */
1560 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
1562 /* If both are anti-ranges, then we cannot compute any
1564 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
1567 /* These comparisons are never statically computable. */
1574 /* Equality can be computed only between a range and an
1575 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
1576 if (vr0->type == VR_RANGE)
1578 /* To simplify processing, make VR0 the anti-range. */
1579 value_range_t *tmp = vr0;
1584 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
1586 if (compare_values (vr0->min, vr1->min) == 0
1587 && compare_values (vr0->max, vr1->max) == 0)
1588 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
1593 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
1594 operands around and change the comparison code. */
1595 if (comp == GT_EXPR || comp == GE_EXPR)
1598 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
1604 if (comp == EQ_EXPR)
1606 /* Equality may only be computed if both ranges represent
1607 exactly one value. */
1608 if (compare_values (vr0->min, vr0->max) == 0
1609 && compare_values (vr1->min, vr1->max) == 0)
1611 int cmp_min = compare_values (vr0->min, vr1->min);
1612 int cmp_max = compare_values (vr0->max, vr1->max);
1613 if (cmp_min == 0 && cmp_max == 0)
1614 return boolean_true_node;
1615 else if (cmp_min != -2 && cmp_max != -2)
1616 return boolean_false_node;
1621 else if (comp == NE_EXPR)
1625 /* If VR0 is completely to the left or completely to the right
1626 of VR1, they are always different. Notice that we need to
1627 make sure that both comparisons yield similar results to
1628 avoid comparing values that cannot be compared at
1630 cmp1 = compare_values (vr0->max, vr1->min);
1631 cmp2 = compare_values (vr0->min, vr1->max);
1632 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
1633 return boolean_true_node;
1635 /* If VR0 and VR1 represent a single value and are identical,
1637 else if (compare_values (vr0->min, vr0->max) == 0
1638 && compare_values (vr1->min, vr1->max) == 0
1639 && compare_values (vr0->min, vr1->min) == 0
1640 && compare_values (vr0->max, vr1->max) == 0)
1641 return boolean_false_node;
1643 /* Otherwise, they may or may not be different. */
1647 else if (comp == LT_EXPR || comp == LE_EXPR)
1651 /* If VR0 is to the left of VR1, return true. */
1652 tst = compare_values (vr0->max, vr1->min);
1653 if ((comp == LT_EXPR && tst == -1)
1654 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
1655 return boolean_true_node;
1657 /* If VR0 is to the right of VR1, return false. */
1658 tst = compare_values (vr0->min, vr1->max);
1659 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
1660 || (comp == LE_EXPR && tst == 1))
1661 return boolean_false_node;
1663 /* Otherwise, we don't know. */
1671 /* Given a value range VR, a value VAL and a comparison code COMP, return
1672 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
1673 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
1674 always returns false. Return NULL_TREE if it is not always
1675 possible to determine the value of the comparison. */
1678 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val)
1680 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
1683 /* Anti-ranges need to be handled separately. */
1684 if (vr->type == VR_ANTI_RANGE)
1686 /* For anti-ranges, the only predicates that we can compute at
1687 compile time are equality and inequality. */
1694 /* ~[VAL, VAL] == VAL is always false. */
1695 if (compare_values (vr->min, val) == 0
1696 && compare_values (vr->max, val) == 0)
1697 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
1702 if (comp == EQ_EXPR)
1704 /* EQ_EXPR may only be computed if VR represents exactly
1706 if (compare_values (vr->min, vr->max) == 0)
1708 int cmp = compare_values (vr->min, val);
1710 return boolean_true_node;
1711 else if (cmp == -1 || cmp == 1 || cmp == 2)
1712 return boolean_false_node;
1714 else if (compare_values (val, vr->min) == -1
1715 || compare_values (vr->max, val) == -1)
1716 return boolean_false_node;
1720 else if (comp == NE_EXPR)
1722 /* If VAL is not inside VR, then they are always different. */
1723 if (compare_values (vr->max, val) == -1
1724 || compare_values (vr->min, val) == 1)
1725 return boolean_true_node;
1727 /* If VR represents exactly one value equal to VAL, then return
1729 if (compare_values (vr->min, vr->max) == 0
1730 && compare_values (vr->min, val) == 0)
1731 return boolean_false_node;
1733 /* Otherwise, they may or may not be different. */
1736 else if (comp == LT_EXPR || comp == LE_EXPR)
1740 /* If VR is to the left of VAL, return true. */
1741 tst = compare_values (vr->max, val);
1742 if ((comp == LT_EXPR && tst == -1)
1743 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
1744 return boolean_true_node;
1746 /* If VR is to the right of VAL, return false. */
1747 tst = compare_values (vr->min, val);
1748 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
1749 || (comp == LE_EXPR && tst == 1))
1750 return boolean_false_node;
1752 /* Otherwise, we don't know. */
1755 else if (comp == GT_EXPR || comp == GE_EXPR)
1759 /* If VR is to the right of VAL, return true. */
1760 tst = compare_values (vr->min, val);
1761 if ((comp == GT_EXPR && tst == 1)
1762 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
1763 return boolean_true_node;
1765 /* If VR is to the left of VAL, return false. */
1766 tst = compare_values (vr->max, val);
1767 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
1768 || (comp == GE_EXPR && tst == -1))
1769 return boolean_false_node;
1771 /* Otherwise, we don't know. */
1779 /* Debugging dumps. */
1781 void dump_value_range (FILE *, value_range_t *);
1782 void debug_value_range (value_range_t *);
1783 void dump_all_value_ranges (FILE *);
1784 void debug_all_value_ranges (void);
1785 void dump_vr_equiv (FILE *, bitmap);
1786 void debug_vr_equiv (bitmap);
1789 /* Dump value range VR to FILE. */
1792 dump_value_range (FILE *file, value_range_t *vr)
1795 fprintf (file, "[]");
1796 else if (vr->type == VR_UNDEFINED)
1797 fprintf (file, "UNDEFINED");
1798 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
1800 tree type = TREE_TYPE (vr->min);
1802 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
1804 if (INTEGRAL_TYPE_P (type)
1805 && !TYPE_UNSIGNED (type)
1806 && vr->min == TYPE_MIN_VALUE (type))
1807 fprintf (file, "-INF");
1809 print_generic_expr (file, vr->min, 0);
1811 fprintf (file, ", ");
1813 if (INTEGRAL_TYPE_P (type)
1814 && vr->max == TYPE_MAX_VALUE (type))
1815 fprintf (file, "+INF");
1817 print_generic_expr (file, vr->max, 0);
1819 fprintf (file, "]");
1826 fprintf (file, " EQUIVALENCES: { ");
1828 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
1830 print_generic_expr (file, ssa_name (i), 0);
1831 fprintf (file, " ");
1835 fprintf (file, "} (%u elements)", c);
1838 else if (vr->type == VR_VARYING)
1839 fprintf (file, "VARYING");
1841 fprintf (file, "INVALID RANGE");
1845 /* Dump value range VR to stderr. */
1848 debug_value_range (value_range_t *vr)
1850 dump_value_range (stderr, vr);
1854 /* Dump value ranges of all SSA_NAMEs to FILE. */
1857 dump_all_value_ranges (FILE *file)
1861 for (i = 0; i < num_ssa_names; i++)
1865 print_generic_expr (file, ssa_name (i), 0);
1866 fprintf (file, ": ");
1867 dump_value_range (file, vr_value[i]);
1868 fprintf (file, "\n");
1872 fprintf (file, "\n");
1876 /* Dump all value ranges to stderr. */
1879 debug_all_value_ranges (void)
1881 dump_all_value_ranges (stderr);
1885 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
1886 create a new SSA name N and return the assertion assignment
1887 'V = ASSERT_EXPR <V, V OP W>'. */
1890 build_assert_expr_for (tree cond, tree v)
1894 gcc_assert (TREE_CODE (v) == SSA_NAME);
1895 n = duplicate_ssa_name (v, NULL_TREE);
1897 if (COMPARISON_CLASS_P (cond))
1899 tree a = build (ASSERT_EXPR, TREE_TYPE (v), v, cond);
1900 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, a);
1902 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
1904 /* Given !V, build the assignment N = false. */
1905 tree op0 = TREE_OPERAND (cond, 0);
1906 gcc_assert (op0 == v);
1907 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, boolean_false_node);
1909 else if (TREE_CODE (cond) == SSA_NAME)
1911 /* Given V, build the assignment N = true. */
1912 gcc_assert (v == cond);
1913 assertion = build (MODIFY_EXPR, TREE_TYPE (v), n, boolean_true_node);
1918 SSA_NAME_DEF_STMT (n) = assertion;
1920 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
1921 operand of the ASSERT_EXPR. Register the new name and the old one
1922 in the replacement table so that we can fix the SSA web after
1923 adding all the ASSERT_EXPRs. */
1924 register_new_name_mapping (n, v);
1930 /* Return false if EXPR is a predicate expression involving floating
1934 fp_predicate (tree expr)
1936 return (COMPARISON_CLASS_P (expr)
1937 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
1941 /* If the range of values taken by OP can be inferred after STMT executes,
1942 return the comparison code (COMP_CODE_P) and value (VAL_P) that
1943 describes the inferred range. Return true if a range could be
1947 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
1950 *comp_code_p = ERROR_MARK;
1952 /* Do not attempt to infer anything in names that flow through
1954 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
1957 /* Similarly, don't infer anything from statements that may throw
1959 if (tree_could_throw_p (stmt))
1962 if (POINTER_TYPE_P (TREE_TYPE (op)))
1965 unsigned num_uses, num_derefs;
1967 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
1968 if (num_derefs > 0 && flag_delete_null_pointer_checks)
1970 /* We can only assume that a pointer dereference will yield
1971 non-NULL if -fdelete-null-pointer-checks is enabled. */
1972 *val_p = build_int_cst (TREE_TYPE (op), 0);
1973 *comp_code_p = NE_EXPR;
1982 void dump_asserts_for (FILE *, tree);
1983 void debug_asserts_for (tree);
1984 void dump_all_asserts (FILE *);
1985 void debug_all_asserts (void);
1987 /* Dump all the registered assertions for NAME to FILE. */
1990 dump_asserts_for (FILE *file, tree name)
1994 fprintf (file, "Assertions to be inserted for ");
1995 print_generic_expr (file, name, 0);
1996 fprintf (file, "\n");
1998 loc = asserts_for[SSA_NAME_VERSION (name)];
2001 fprintf (file, "\t");
2002 print_generic_expr (file, bsi_stmt (loc->si), 0);
2003 fprintf (file, "\n\tBB #%d", loc->bb->index);
2006 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
2007 loc->e->dest->index);
2008 dump_edge_info (file, loc->e, 0);
2010 fprintf (file, "\n\tPREDICATE: ");
2011 print_generic_expr (file, name, 0);
2012 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
2013 print_generic_expr (file, loc->val, 0);
2014 fprintf (file, "\n\n");
2018 fprintf (file, "\n");
2022 /* Dump all the registered assertions for NAME to stderr. */
2025 debug_asserts_for (tree name)
2027 dump_asserts_for (stderr, name);
2031 /* Dump all the registered assertions for all the names to FILE. */
2034 dump_all_asserts (FILE *file)
2039 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
2040 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2041 dump_asserts_for (file, ssa_name (i));
2042 fprintf (file, "\n");
2046 /* Dump all the registered assertions for all the names to stderr. */
2049 debug_all_asserts (void)
2051 dump_all_asserts (stderr);
2055 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2056 'NAME COMP_CODE VAL' at a location that dominates block BB or
2057 E->DEST, then register this location as a possible insertion point
2058 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2060 BB, E and SI provide the exact insertion point for the new
2061 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2062 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2063 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2064 must not be NULL. */
2067 register_new_assert_for (tree name,
2068 enum tree_code comp_code,
2072 block_stmt_iterator si)
2074 assert_locus_t n, loc, last_loc;
2076 basic_block dest_bb;
2078 #if defined ENABLE_CHECKING
2079 gcc_assert (bb == NULL || e == NULL);
2082 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
2083 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
2086 /* The new assertion A will be inserted at BB or E. We need to
2087 determine if the new location is dominated by a previously
2088 registered location for A. If we are doing an edge insertion,
2089 assume that A will be inserted at E->DEST. Note that this is not
2092 If E is a critical edge, it will be split. But even if E is
2093 split, the new block will dominate the same set of blocks that
2096 The reverse, however, is not true, blocks dominated by E->DEST
2097 will not be dominated by the new block created to split E. So,
2098 if the insertion location is on a critical edge, we will not use
2099 the new location to move another assertion previously registered
2100 at a block dominated by E->DEST. */
2101 dest_bb = (bb) ? bb : e->dest;
2103 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2104 VAL at a block dominating DEST_BB, then we don't need to insert a new
2105 one. Similarly, if the same assertion already exists at a block
2106 dominated by DEST_BB and the new location is not on a critical
2107 edge, then update the existing location for the assertion (i.e.,
2108 move the assertion up in the dominance tree).
2110 Note, this is implemented as a simple linked list because there
2111 should not be more than a handful of assertions registered per
2112 name. If this becomes a performance problem, a table hashed by
2113 COMP_CODE and VAL could be implemented. */
2114 loc = asserts_for[SSA_NAME_VERSION (name)];
2119 if (loc->comp_code == comp_code
2121 || operand_equal_p (loc->val, val, 0)))
2123 /* If the assertion NAME COMP_CODE VAL has already been
2124 registered at a basic block that dominates DEST_BB, then
2125 we don't need to insert the same assertion again. Note
2126 that we don't check strict dominance here to avoid
2127 replicating the same assertion inside the same basic
2128 block more than once (e.g., when a pointer is
2129 dereferenced several times inside a block).
2131 An exception to this rule are edge insertions. If the
2132 new assertion is to be inserted on edge E, then it will
2133 dominate all the other insertions that we may want to
2134 insert in DEST_BB. So, if we are doing an edge
2135 insertion, don't do this dominance check. */
2137 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
2140 /* Otherwise, if E is not a critical edge and DEST_BB
2141 dominates the existing location for the assertion, move
2142 the assertion up in the dominance tree by updating its
2143 location information. */
2144 if ((e == NULL || !EDGE_CRITICAL_P (e))
2145 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
2154 /* Update the last node of the list and move to the next one. */
2159 /* If we didn't find an assertion already registered for
2160 NAME COMP_CODE VAL, add a new one at the end of the list of
2161 assertions associated with NAME. */
2162 n = xmalloc (sizeof (*n));
2166 n->comp_code = comp_code;
2173 asserts_for[SSA_NAME_VERSION (name)] = n;
2175 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
2179 /* Try to register an edge assertion for SSA name NAME on edge E for
2180 the conditional jump pointed by SI. Return true if an assertion
2181 for NAME could be registered. */
2184 register_edge_assert_for (tree name, edge e, block_stmt_iterator si)
2187 enum tree_code comp_code;
2189 stmt = bsi_stmt (si);
2191 /* Do not attempt to infer anything in names that flow through
2193 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
2196 /* If NAME was not found in the sub-graph reachable from E, then
2197 there's nothing to do. */
2198 if (!TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
2201 /* We found a use of NAME in the sub-graph rooted at E->DEST.
2202 Register an assertion for NAME according to the value that NAME
2204 if (TREE_CODE (stmt) == COND_EXPR)
2206 /* If BB ends in a COND_EXPR then NAME then we should insert
2207 the original predicate on EDGE_TRUE_VALUE and the
2208 opposite predicate on EDGE_FALSE_VALUE. */
2209 tree cond = COND_EXPR_COND (stmt);
2210 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
2212 /* Predicates may be a single SSA name or NAME OP VAL. */
2215 /* If the predicate is a name, it must be NAME, in which
2216 case we create the predicate NAME == true or
2217 NAME == false accordingly. */
2218 comp_code = EQ_EXPR;
2219 val = (is_else_edge) ? boolean_false_node : boolean_true_node;
2223 /* Otherwise, we have a comparison of the form NAME COMP VAL
2224 or VAL COMP NAME. */
2225 if (name == TREE_OPERAND (cond, 1))
2227 /* If the predicate is of the form VAL COMP NAME, flip
2228 COMP around because we need to register NAME as the
2229 first operand in the predicate. */
2230 comp_code = swap_tree_comparison (TREE_CODE (cond));
2231 val = TREE_OPERAND (cond, 0);
2235 /* The comparison is of the form NAME COMP VAL, so the
2236 comparison code remains unchanged. */
2237 comp_code = TREE_CODE (cond);
2238 val = TREE_OPERAND (cond, 1);
2241 /* If we are inserting the assertion on the ELSE edge, we
2242 need to invert the sign comparison. */
2244 comp_code = invert_tree_comparison (comp_code, 0);
2249 /* FIXME. Handle SWITCH_EXPR. */
2253 register_new_assert_for (name, comp_code, val, NULL, e, si);
2258 static bool find_assert_locations (basic_block bb);
2260 /* Determine whether the outgoing edges of BB should receive an
2261 ASSERT_EXPR for each of the operands of BB's last statement. The
2262 last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2264 If any of the sub-graphs rooted at BB have an interesting use of
2265 the predicate operands, an assert location node is added to the
2266 list of assertions for the corresponding operands. */
2269 find_conditional_asserts (basic_block bb)
2272 block_stmt_iterator last_si;
2278 need_assert = false;
2279 last_si = bsi_last (bb);
2280 last = bsi_stmt (last_si);
2282 /* Look for uses of the operands in each of the sub-graphs
2283 rooted at BB. We need to check each of the outgoing edges
2284 separately, so that we know what kind of ASSERT_EXPR to
2286 FOR_EACH_EDGE (e, ei, bb->succs)
2291 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
2292 Otherwise, when we finish traversing each of the sub-graphs, we
2293 won't know whether the variables were found in the sub-graphs or
2294 if they had been found in a block upstream from BB. */
2295 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2296 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2298 /* Traverse the strictly dominated sub-graph rooted at E->DEST
2299 to determine if any of the operands in the conditional
2300 predicate are used. */
2302 need_assert |= find_assert_locations (e->dest);
2304 /* Register the necessary assertions for each operand in the
2305 conditional predicate. */
2306 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2307 need_assert |= register_edge_assert_for (op, e, last_si);
2310 /* Finally, indicate that we have found the operands in the
2312 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
2313 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2319 /* Traverse all the statements in block BB looking for statements that
2320 may generate useful assertions for the SSA names in their operand.
2321 If a statement produces a useful assertion A for name N_i, then the
2322 list of assertions already generated for N_i is scanned to
2323 determine if A is actually needed.
2325 If N_i already had the assertion A at a location dominating the
2326 current location, then nothing needs to be done. Otherwise, the
2327 new location for A is recorded instead.
2329 1- For every statement S in BB, all the variables used by S are
2330 added to bitmap FOUND_IN_SUBGRAPH.
2332 2- If statement S uses an operand N in a way that exposes a known
2333 value range for N, then if N was not already generated by an
2334 ASSERT_EXPR, create a new assert location for N. For instance,
2335 if N is a pointer and the statement dereferences it, we can
2336 assume that N is not NULL.
2338 3- COND_EXPRs are a special case of #2. We can derive range
2339 information from the predicate but need to insert different
2340 ASSERT_EXPRs for each of the sub-graphs rooted at the
2341 conditional block. If the last statement of BB is a conditional
2342 expression of the form 'X op Y', then
2344 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
2346 b) If the conditional is the only entry point to the sub-graph
2347 corresponding to the THEN_CLAUSE, recurse into it. On
2348 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
2349 an ASSERT_EXPR is added for the corresponding variable.
2351 c) Repeat step (b) on the ELSE_CLAUSE.
2353 d) Mark X and Y in FOUND_IN_SUBGRAPH.
2362 In this case, an assertion on the THEN clause is useful to
2363 determine that 'a' is always 9 on that edge. However, an assertion
2364 on the ELSE clause would be unnecessary.
2366 4- If BB does not end in a conditional expression, then we recurse
2367 into BB's dominator children.
2369 At the end of the recursive traversal, every SSA name will have a
2370 list of locations where ASSERT_EXPRs should be added. When a new
2371 location for name N is found, it is registered by calling
2372 register_new_assert_for. That function keeps track of all the
2373 registered assertions to prevent adding unnecessary assertions.
2374 For instance, if a pointer P_4 is dereferenced more than once in a
2375 dominator tree, only the location dominating all the dereference of
2376 P_4 will receive an ASSERT_EXPR.
2378 If this function returns true, then it means that there are names
2379 for which we need to generate ASSERT_EXPRs. Those assertions are
2380 inserted by process_assert_insertions.
2382 TODO. Handle SWITCH_EXPR. */
2385 find_assert_locations (basic_block bb)
2387 block_stmt_iterator si;
2392 if (TEST_BIT (blocks_visited, bb->index))
2395 SET_BIT (blocks_visited, bb->index);
2397 need_assert = false;
2399 /* Traverse all PHI nodes in BB marking used operands. */
2400 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
2402 use_operand_p arg_p;
2405 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
2407 tree arg = USE_FROM_PTR (arg_p);
2408 if (TREE_CODE (arg) == SSA_NAME)
2410 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
2411 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
2416 /* Traverse all the statements in BB marking used names and looking
2417 for statements that may infer assertions for their used operands. */
2419 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
2424 stmt = bsi_stmt (si);
2426 /* See if we can derive an assertion for any of STMT's operands. */
2427 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
2430 enum tree_code comp_code;
2432 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
2433 the sub-graph of a conditional block, when we return from
2434 this recursive walk, our parent will use the
2435 FOUND_IN_SUBGRAPH bitset to determine if one of the
2436 operands it was looking for was present in the sub-graph. */
2437 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
2439 /* If OP is used only once, namely in this STMT, don't
2440 bother creating an ASSERT_EXPR for it. Such an
2441 ASSERT_EXPR would do nothing but increase compile time.
2442 Experiments show that with this simple check, we can save
2443 more than 20% of ASSERT_EXPRs. */
2444 if (has_single_use (op))
2447 /* If OP is used in such a way that we can infer a value
2448 range for it, and we don't find a previous assertion for
2449 it, create a new assertion location node for OP. */
2450 if (infer_value_range (stmt, op, &comp_code, &value))
2452 register_new_assert_for (op, comp_code, value, bb, NULL, si);
2457 /* Remember the last statement of the block. */
2461 /* If BB's last statement is a conditional expression
2462 involving integer operands, recurse into each of the sub-graphs
2463 rooted at BB to determine if we need to add ASSERT_EXPRs. */
2465 && TREE_CODE (last) == COND_EXPR
2466 && !fp_predicate (COND_EXPR_COND (last))
2467 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
2468 need_assert |= find_conditional_asserts (bb);
2470 /* Recurse into the dominator children of BB. */
2471 for (son = first_dom_son (CDI_DOMINATORS, bb);
2473 son = next_dom_son (CDI_DOMINATORS, son))
2474 need_assert |= find_assert_locations (son);
2480 /* Create an ASSERT_EXPR for NAME and insert it in the location
2481 indicated by LOC. Return true if we made any edge insertions. */
2484 process_assert_insertions_for (tree name, assert_locus_t loc)
2486 /* Build the comparison expression NAME_i COMP_CODE VAL. */
2487 tree stmt, cond, assert_expr;
2491 cond = build (loc->comp_code, boolean_type_node, name, loc->val);
2492 assert_expr = build_assert_expr_for (cond, name);
2496 /* We have been asked to insert the assertion on an edge. This
2497 is used only by COND_EXPR and SWITCH_EXPR assertions. */
2498 #if defined ENABLE_CHECKING
2499 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
2500 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
2503 bsi_insert_on_edge (loc->e, assert_expr);
2507 /* Otherwise, we can insert right after LOC->SI iff the
2508 statement must not be the last statement in the block. */
2509 stmt = bsi_stmt (loc->si);
2510 if (!stmt_ends_bb_p (stmt))
2512 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
2516 /* If STMT must be the last statement in BB, we can only insert new
2517 assertions on the non-abnormal edge out of BB. Note that since
2518 STMT is not control flow, there may only be one non-abnormal edge
2520 FOR_EACH_EDGE (e, ei, loc->bb->succs)
2521 if (!(e->flags & EDGE_ABNORMAL))
2523 bsi_insert_on_edge (e, assert_expr);
2531 /* Process all the insertions registered for every name N_i registered
2532 in NEED_ASSERT_FOR. The list of assertions to be inserted are
2533 found in ASSERTS_FOR[i]. */
2536 process_assert_insertions (void)
2540 bool update_edges_p = false;
2541 int num_asserts = 0;
2543 if (dump_file && (dump_flags & TDF_DETAILS))
2544 dump_all_asserts (dump_file);
2546 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2548 assert_locus_t loc = asserts_for[i];
2553 assert_locus_t next = loc->next;
2554 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
2562 bsi_commit_edge_inserts ();
2564 if (dump_file && (dump_flags & TDF_STATS))
2565 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
2570 /* Traverse the flowgraph looking for conditional jumps to insert range
2571 expressions. These range expressions are meant to provide information
2572 to optimizations that need to reason in terms of value ranges. They
2573 will not be expanded into RTL. For instance, given:
2582 this pass will transform the code into:
2588 x = ASSERT_EXPR <x, x < y>
2593 y = ASSERT_EXPR <y, x <= y>
2597 The idea is that once copy and constant propagation have run, other
2598 optimizations will be able to determine what ranges of values can 'x'
2599 take in different paths of the code, simply by checking the reaching
2600 definition of 'x'. */
2603 insert_range_assertions (void)
2609 found_in_subgraph = sbitmap_alloc (num_ssa_names);
2610 sbitmap_zero (found_in_subgraph);
2612 blocks_visited = sbitmap_alloc (last_basic_block);
2613 sbitmap_zero (blocks_visited);
2615 need_assert_for = BITMAP_ALLOC (NULL);
2616 asserts_for = xmalloc (num_ssa_names * sizeof (assert_locus_t));
2617 memset (asserts_for, 0, num_ssa_names * sizeof (assert_locus_t));
2619 calculate_dominance_info (CDI_DOMINATORS);
2621 update_ssa_p = false;
2622 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2623 if (find_assert_locations (e->dest))
2624 update_ssa_p = true;
2628 process_assert_insertions ();
2629 update_ssa (TODO_update_ssa_no_phi);
2632 if (dump_file && (dump_flags & TDF_DETAILS))
2634 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
2635 dump_function_to_file (current_function_decl, dump_file, dump_flags);
2638 sbitmap_free (found_in_subgraph);
2640 BITMAP_FREE (need_assert_for);
2644 /* Convert range assertion expressions into the implied copies.
2646 FIXME, this will eventually lead to copy propagation removing the
2647 names that had useful range information attached to them. For
2648 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
2649 then N_i will have the range [3, +INF].
2651 However, by converting the assertion into the implied copy
2652 operation N_i = N_j, we will then copy-propagate N_j into the uses
2653 of N_i and lose the range information. We may want to hold on to
2654 ASSERT_EXPRs a little while longer as the ranges could be used in
2655 things like jump threading.
2657 The problem with keeping ASSERT_EXPRs around is that passes after
2658 VRP need to handle them appropriately. */
2661 remove_range_assertions (void)
2664 block_stmt_iterator si;
2667 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
2669 tree stmt = bsi_stmt (si);
2671 if (TREE_CODE (stmt) == MODIFY_EXPR
2672 && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR)
2674 tree rhs = TREE_OPERAND (stmt, 1);
2675 tree cond = fold (ASSERT_EXPR_COND (rhs));
2676 gcc_assert (cond != boolean_false_node);
2677 TREE_OPERAND (stmt, 1) = ASSERT_EXPR_VAR (rhs);
2684 /* Return true if STMT is interesting for VRP. */
2687 stmt_interesting_for_vrp (tree stmt)
2689 if (TREE_CODE (stmt) == PHI_NODE
2690 && is_gimple_reg (PHI_RESULT (stmt))
2691 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
2692 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
2694 else if (TREE_CODE (stmt) == MODIFY_EXPR)
2696 tree lhs = TREE_OPERAND (stmt, 0);
2698 if (TREE_CODE (lhs) == SSA_NAME
2699 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
2700 || POINTER_TYPE_P (TREE_TYPE (lhs)))
2701 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
2704 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
2711 /* Initialize local data structures for VRP. Return true if VRP
2712 is worth running (i.e. if we found any statements that could
2713 benefit from range information). */
2716 vrp_initialize (void)
2720 vr_value = xmalloc (num_ssa_names * sizeof (value_range_t *));
2721 memset (vr_value, 0, num_ssa_names * sizeof (value_range_t *));
2725 block_stmt_iterator si;
2728 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
2730 if (!stmt_interesting_for_vrp (phi))
2732 tree lhs = PHI_RESULT (phi);
2733 set_value_range_to_varying (get_value_range (lhs));
2734 DONT_SIMULATE_AGAIN (phi) = true;
2737 DONT_SIMULATE_AGAIN (phi) = false;
2740 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
2742 tree stmt = bsi_stmt (si);
2744 if (!stmt_interesting_for_vrp (stmt))
2748 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
2749 set_value_range_to_varying (get_value_range (def));
2750 DONT_SIMULATE_AGAIN (stmt) = true;
2754 DONT_SIMULATE_AGAIN (stmt) = false;
2761 /* Visit assignment STMT. If it produces an interesting range, record
2762 the SSA name in *OUTPUT_P. */
2764 static enum ssa_prop_result
2765 vrp_visit_assignment (tree stmt, tree *output_p)
2770 lhs = TREE_OPERAND (stmt, 0);
2771 rhs = TREE_OPERAND (stmt, 1);
2773 /* We only keep track of ranges in integral and pointer types. */
2774 if (TREE_CODE (lhs) == SSA_NAME
2775 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
2776 || POINTER_TYPE_P (TREE_TYPE (lhs))))
2779 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2781 extract_range_from_expr (&new_vr, rhs);
2783 /* If STMT is inside a loop, we may be able to know something
2784 else about the range of LHS by examining scalar evolution
2786 if (cfg_loops && (l = loop_containing_stmt (stmt)))
2787 adjust_range_with_scev (&new_vr, l, stmt, lhs);
2789 if (update_value_range (lhs, &new_vr))
2793 if (dump_file && (dump_flags & TDF_DETAILS))
2795 fprintf (dump_file, "Found new range for ");
2796 print_generic_expr (dump_file, lhs, 0);
2797 fprintf (dump_file, ": ");
2798 dump_value_range (dump_file, &new_vr);
2799 fprintf (dump_file, "\n\n");
2802 if (new_vr.type == VR_VARYING)
2803 return SSA_PROP_VARYING;
2805 return SSA_PROP_INTERESTING;
2808 return SSA_PROP_NOT_INTERESTING;
2811 /* Every other statement produces no useful ranges. */
2812 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
2813 set_value_range_to_varying (get_value_range (def));
2815 return SSA_PROP_VARYING;
2819 /* Compare all the value ranges for names equivalent to VAR with VAL
2820 using comparison code COMP. Return the same value returned by
2821 compare_range_with_value. */
2824 compare_name_with_value (enum tree_code comp, tree var, tree val)
2831 t = retval = NULL_TREE;
2833 /* Get the set of equivalences for VAR. */
2834 e = get_value_range (var)->equiv;
2836 /* Add VAR to its own set of equivalences so that VAR's value range
2837 is processed by this loop (otherwise, we would have to replicate
2838 the body of the loop just to check VAR's value range). */
2839 bitmap_set_bit (e, SSA_NAME_VERSION (var));
2841 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
2843 value_range_t equiv_vr = *(vr_value[i]);
2845 /* If name N_i does not have a valid range, use N_i as its own
2846 range. This allows us to compare against names that may
2847 have N_i in their ranges. */
2848 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
2850 equiv_vr.type = VR_RANGE;
2851 equiv_vr.min = ssa_name (i);
2852 equiv_vr.max = ssa_name (i);
2855 t = compare_range_with_value (comp, &equiv_vr, val);
2858 /* All the ranges should compare the same against VAL. */
2859 gcc_assert (retval == NULL || t == retval);
2864 /* Remove VAR from its own equivalence set. */
2865 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
2870 /* We couldn't find a non-NULL value for the predicate. */
2875 /* Given a comparison code COMP and names N1 and N2, compare all the
2876 ranges equivalent to N1 against all the ranges equivalent to N2
2877 to determine the value of N1 COMP N2. Return the same value
2878 returned by compare_ranges. */
2881 compare_names (enum tree_code comp, tree n1, tree n2)
2885 bitmap_iterator bi1, bi2;
2888 /* Compare the ranges of every name equivalent to N1 against the
2889 ranges of every name equivalent to N2. */
2890 e1 = get_value_range (n1)->equiv;
2891 e2 = get_value_range (n2)->equiv;
2893 /* Add N1 and N2 to their own set of equivalences to avoid
2894 duplicating the body of the loop just to check N1 and N2
2896 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
2897 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
2899 /* If the equivalence sets have a common intersection, then the two
2900 names can be compared without checking their ranges. */
2901 if (bitmap_intersect_p (e1, e2))
2903 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
2904 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
2906 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
2908 : boolean_false_node;
2911 /* Otherwise, compare all the equivalent ranges. First, add N1 and
2912 N2 to their own set of equivalences to avoid duplicating the body
2913 of the loop just to check N1 and N2 ranges. */
2914 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
2916 value_range_t vr1 = *(vr_value[i1]);
2918 /* If the range is VARYING or UNDEFINED, use the name itself. */
2919 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
2921 vr1.type = VR_RANGE;
2922 vr1.min = ssa_name (i1);
2923 vr1.max = ssa_name (i1);
2926 t = retval = NULL_TREE;
2927 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
2929 value_range_t vr2 = *(vr_value[i2]);
2931 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
2933 vr2.type = VR_RANGE;
2934 vr2.min = ssa_name (i2);
2935 vr2.max = ssa_name (i2);
2938 t = compare_ranges (comp, &vr1, &vr2);
2941 /* All the ranges in the equivalent sets should compare
2943 gcc_assert (retval == NULL || t == retval);
2950 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
2951 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
2956 /* None of the equivalent ranges are useful in computing this
2958 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
2959 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
2964 /* Given a conditional predicate COND, try to determine if COND yields
2965 true or false based on the value ranges of its operands. Return
2966 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
2967 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
2968 NULL if the conditional cannot be evaluated at compile time.
2970 If USE_EQUIV_P is true, the ranges of all the names equivalent with
2971 the operands in COND are used when trying to compute its value.
2972 This is only used during final substitution. During propagation,
2973 we only check the range of each variable and not its equivalents. */
2976 vrp_evaluate_conditional (tree cond, bool use_equiv_p)
2978 gcc_assert (TREE_CODE (cond) == SSA_NAME
2979 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
2981 if (TREE_CODE (cond) == SSA_NAME)
2987 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node);
2990 value_range_t *vr = get_value_range (cond);
2991 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node);
2994 /* If COND has a known boolean range, return it. */
2998 /* Otherwise, if COND has a symbolic range of exactly one value,
3000 vr = get_value_range (cond);
3001 if (vr->type == VR_RANGE && vr->min == vr->max)
3006 tree op0 = TREE_OPERAND (cond, 0);
3007 tree op1 = TREE_OPERAND (cond, 1);
3009 /* We only deal with integral and pointer types. */
3010 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
3011 && !POINTER_TYPE_P (TREE_TYPE (op0)))
3016 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
3017 return compare_names (TREE_CODE (cond), op0, op1);
3018 else if (TREE_CODE (op0) == SSA_NAME)
3019 return compare_name_with_value (TREE_CODE (cond), op0, op1);
3020 else if (TREE_CODE (op1) == SSA_NAME)
3021 return compare_name_with_value (
3022 swap_tree_comparison (TREE_CODE (cond)), op1, op0);
3026 value_range_t *vr0, *vr1;
3028 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
3029 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
3032 return compare_ranges (TREE_CODE (cond), vr0, vr1);
3033 else if (vr0 && vr1 == NULL)
3034 return compare_range_with_value (TREE_CODE (cond), vr0, op1);
3035 else if (vr0 == NULL && vr1)
3036 return compare_range_with_value (
3037 swap_tree_comparison (TREE_CODE (cond)), vr1, op0);
3041 /* Anything else cannot be computed statically. */
3046 /* Visit conditional statement STMT. If we can determine which edge
3047 will be taken out of STMT's basic block, record it in
3048 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3049 SSA_PROP_VARYING. */
3051 static enum ssa_prop_result
3052 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
3056 *taken_edge_p = NULL;
3058 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3059 add ASSERT_EXPRs for them. */
3060 if (TREE_CODE (stmt) == SWITCH_EXPR)
3061 return SSA_PROP_VARYING;
3063 cond = COND_EXPR_COND (stmt);
3065 if (dump_file && (dump_flags & TDF_DETAILS))
3070 fprintf (dump_file, "\nVisiting conditional with predicate: ");
3071 print_generic_expr (dump_file, cond, 0);
3072 fprintf (dump_file, "\nWith known ranges\n");
3074 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
3076 fprintf (dump_file, "\t");
3077 print_generic_expr (dump_file, use, 0);
3078 fprintf (dump_file, ": ");
3079 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
3082 fprintf (dump_file, "\n");
3085 /* Compute the value of the predicate COND by checking the known
3086 ranges of each of its operands.
3088 Note that we cannot evaluate all the equivalent ranges here
3089 because those ranges may not yet be final and with the current
3090 propagation strategy, we cannot determine when the value ranges
3091 of the names in the equivalence set have changed.
3093 For instance, given the following code fragment
3097 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3101 Assume that on the first visit to i_14, i_5 has the temporary
3102 range [8, 8] because the second argument to the PHI function is
3103 not yet executable. We derive the range ~[0, 0] for i_14 and the
3104 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3105 the first time, since i_14 is equivalent to the range [8, 8], we
3106 determine that the predicate is always false.
3108 On the next round of propagation, i_13 is determined to be
3109 VARYING, which causes i_5 to drop down to VARYING. So, another
3110 visit to i_14 is scheduled. In this second visit, we compute the
3111 exact same range and equivalence set for i_14, namely ~[0, 0] and
3112 { i_5 }. But we did not have the previous range for i_5
3113 registered, so vrp_visit_assignment thinks that the range for
3114 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3115 is not visited again, which stops propagation from visiting
3116 statements in the THEN clause of that if().
3118 To properly fix this we would need to keep the previous range
3119 value for the names in the equivalence set. This way we would've
3120 discovered that from one visit to the other i_5 changed from
3121 range [8, 8] to VR_VARYING.
3123 However, fixing this apparent limitation may not be worth the
3124 additional checking. Testing on several code bases (GCC, DLV,
3125 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3126 4 more predicates folded in SPEC. */
3127 val = vrp_evaluate_conditional (cond, false);
3129 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
3131 if (dump_file && (dump_flags & TDF_DETAILS))
3133 fprintf (dump_file, "\nPredicate evaluates to: ");
3134 if (val == NULL_TREE)
3135 fprintf (dump_file, "DON'T KNOW\n");
3137 print_generic_stmt (dump_file, val, 0);
3140 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
3144 /* Evaluate statement STMT. If the statement produces a useful range,
3145 return SSA_PROP_INTERESTING and record the SSA name with the
3146 interesting range into *OUTPUT_P.
3148 If STMT is a conditional branch and we can determine its truth
3149 value, the taken edge is recorded in *TAKEN_EDGE_P.
3151 If STMT produces a varying value, return SSA_PROP_VARYING. */
3153 static enum ssa_prop_result
3154 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
3160 if (dump_file && (dump_flags & TDF_DETAILS))
3162 fprintf (dump_file, "\nVisiting statement:\n");
3163 print_generic_stmt (dump_file, stmt, dump_flags);
3164 fprintf (dump_file, "\n");
3167 ann = stmt_ann (stmt);
3168 if (TREE_CODE (stmt) == MODIFY_EXPR
3169 && ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
3170 return vrp_visit_assignment (stmt, output_p);
3171 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3172 return vrp_visit_cond_stmt (stmt, taken_edge_p);
3174 /* All other statements produce nothing of interest for VRP, so mark
3175 their outputs varying and prevent further simulation. */
3176 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3177 set_value_range_to_varying (get_value_range (def));
3179 return SSA_PROP_VARYING;
3183 /* Meet operation for value ranges. Given two value ranges VR0 and
3184 VR1, store in VR0 the result of meeting VR0 and VR1.
3186 The meeting rules are as follows:
3188 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
3190 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
3191 union of VR0 and VR1. */
3194 vrp_meet (value_range_t *vr0, value_range_t *vr1)
3196 if (vr0->type == VR_UNDEFINED)
3198 copy_value_range (vr0, vr1);
3202 if (vr1->type == VR_UNDEFINED)
3204 /* Nothing to do. VR0 already has the resulting range. */
3208 if (vr0->type == VR_VARYING)
3210 /* Nothing to do. VR0 already has the resulting range. */
3214 if (vr1->type == VR_VARYING)
3216 set_value_range_to_varying (vr0);
3220 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
3222 /* If VR0 and VR1 have a non-empty intersection, compute the
3223 union of both ranges. */
3224 if (value_ranges_intersect_p (vr0, vr1))
3229 /* The lower limit of the new range is the minimum of the
3230 two ranges. If they cannot be compared, the result is
3232 cmp = compare_values (vr0->min, vr1->min);
3233 if (cmp == 0 || cmp == 1)
3239 set_value_range_to_varying (vr0);
3243 /* Similarly, the upper limit of the new range is the
3244 maximum of the two ranges. If they cannot be compared,
3245 the result is VARYING. */
3246 cmp = compare_values (vr0->max, vr1->max);
3247 if (cmp == 0 || cmp == -1)
3253 set_value_range_to_varying (vr0);
3257 /* The resulting set of equivalences is the intersection of
3259 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3260 bitmap_and_into (vr0->equiv, vr1->equiv);
3262 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
3267 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
3269 /* Two anti-ranges meet only if they are both identical. */
3270 if (compare_values (vr0->min, vr1->min) == 0
3271 && compare_values (vr0->max, vr1->max) == 0
3272 && compare_values (vr0->min, vr0->max) == 0)
3274 /* The resulting set of equivalences is the intersection of
3276 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
3277 bitmap_and_into (vr0->equiv, vr1->equiv);
3282 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
3284 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
3285 meet only if the ranges have an empty intersection. The
3286 result of the meet operation is the anti-range. */
3287 if (!symbolic_range_p (vr0)
3288 && !symbolic_range_p (vr1)
3289 && !value_ranges_intersect_p (vr0, vr1))
3291 if (vr1->type == VR_ANTI_RANGE)
3292 copy_value_range (vr0, vr1);
3303 /* The two range VR0 and VR1 do not meet. Before giving up and
3304 setting the result to VARYING, see if we can at least derive a
3305 useful anti-range. */
3306 if (!symbolic_range_p (vr0)
3307 && !range_includes_zero_p (vr0)
3308 && !symbolic_range_p (vr1)
3309 && !range_includes_zero_p (vr1))
3310 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
3312 set_value_range_to_varying (vr0);
3316 /* Visit all arguments for PHI node PHI that flow through executable
3317 edges. If a valid value range can be derived from all the incoming
3318 value ranges, set a new range for the LHS of PHI. */
3320 static enum ssa_prop_result
3321 vrp_visit_phi_node (tree phi)
3324 tree lhs = PHI_RESULT (phi);
3325 value_range_t *lhs_vr = get_value_range (lhs);
3326 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3328 copy_value_range (&vr_result, lhs_vr);
3330 if (dump_file && (dump_flags & TDF_DETAILS))
3332 fprintf (dump_file, "\nVisiting PHI node: ");
3333 print_generic_expr (dump_file, phi, dump_flags);
3336 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
3338 edge e = PHI_ARG_EDGE (phi, i);
3340 if (dump_file && (dump_flags & TDF_DETAILS))
3343 "\n Argument #%d (%d -> %d %sexecutable)\n",
3344 i, e->src->index, e->dest->index,
3345 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
3348 if (e->flags & EDGE_EXECUTABLE)
3350 tree arg = PHI_ARG_DEF (phi, i);
3351 value_range_t vr_arg;
3353 if (TREE_CODE (arg) == SSA_NAME)
3354 vr_arg = *(get_value_range (arg));
3357 vr_arg.type = VR_RANGE;
3360 vr_arg.equiv = NULL;
3363 if (dump_file && (dump_flags & TDF_DETAILS))
3365 fprintf (dump_file, "\t");
3366 print_generic_expr (dump_file, arg, dump_flags);
3367 fprintf (dump_file, "\n\tValue: ");
3368 dump_value_range (dump_file, &vr_arg);
3369 fprintf (dump_file, "\n");
3372 vrp_meet (&vr_result, &vr_arg);
3374 if (vr_result.type == VR_VARYING)
3379 if (vr_result.type == VR_VARYING)
3382 /* To prevent infinite iterations in the algorithm, derive ranges
3383 when the new value is slightly bigger or smaller than the
3385 if (lhs_vr->type == VR_RANGE)
3387 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
3389 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
3390 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
3392 /* If the new minimum is smaller or larger than the previous
3393 one, go all the way to -INF. In the first case, to avoid
3394 iterating millions of times to reach -INF, and in the
3395 other case to avoid infinite bouncing between different
3397 if (cmp_min > 0 || cmp_min < 0)
3398 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
3400 /* Similarly, if the new maximum is smaller or larger than
3401 the previous one, go all the way to +INF. */
3402 if (cmp_max < 0 || cmp_max > 0)
3403 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
3405 /* If we ended up with a (-INF, +INF) range, set it to
3407 if (vr_result.min == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))
3408 && vr_result.max == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)))
3413 /* If the new range is different than the previous value, keep
3415 if (update_value_range (lhs, &vr_result))
3416 return SSA_PROP_INTERESTING;
3418 /* Nothing changed, don't add outgoing edges. */
3419 return SSA_PROP_NOT_INTERESTING;
3421 /* No match found. Set the LHS to VARYING. */
3423 set_value_range_to_varying (lhs_vr);
3424 return SSA_PROP_VARYING;
3427 /* Walk through the IL simplifying expressions using knowledge
3431 simplify_using_ranges (void)
3437 block_stmt_iterator bsi;
3439 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3441 tree stmt = bsi_stmt (bsi);
3443 if (TREE_CODE (stmt) == MODIFY_EXPR)
3445 tree rhs = TREE_OPERAND (stmt, 1);
3446 enum tree_code rhs_code = TREE_CODE (rhs);
3448 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
3449 and BIT_AND_EXPR respectively if the first operand is greater
3450 than zero and the second operand is an exact power of two. */
3451 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
3452 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
3453 && integer_pow2p (TREE_OPERAND (rhs, 1)))
3456 tree op = TREE_OPERAND (rhs, 0);
3457 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
3459 if (TYPE_UNSIGNED (TREE_TYPE (op)))
3461 val = integer_one_node;
3465 val = compare_range_with_value (GT_EXPR, vr,
3469 if (val && integer_onep (val))
3472 tree op0 = TREE_OPERAND (rhs, 0);
3473 tree op1 = TREE_OPERAND (rhs, 1);
3475 if (rhs_code == TRUNC_DIV_EXPR)
3477 t = build_int_cst (NULL_TREE, tree_log2 (op1));
3478 t = build (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
3482 t = build_int_cst (TREE_TYPE (op1), 1);
3483 t = int_const_binop (MINUS_EXPR, op1, t, 0);
3484 t = fold_convert (TREE_TYPE (op0), t);
3485 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
3488 TREE_OPERAND (stmt, 1) = t;
3494 /* Transform ABS (X) into X or -X as appropriate. */
3495 if (rhs_code == ABS_EXPR
3496 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
3497 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
3500 tree op = TREE_OPERAND (rhs, 0);
3501 tree type = TREE_TYPE (op);
3502 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
3504 if (TYPE_UNSIGNED (type))
3506 val = integer_zero_node;
3510 val = compare_range_with_value (LE_EXPR, vr,
3514 val = compare_range_with_value (GE_EXPR, vr,
3519 if (integer_zerop (val))
3520 val = integer_one_node;
3521 else if (integer_onep (val))
3522 val = integer_zero_node;
3527 && (integer_onep (val) || integer_zerop (val)))
3531 if (integer_onep (val))
3532 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
3536 TREE_OPERAND (stmt, 1) = t;
3543 /* TODO. Simplify conditionals. */
3549 /* Traverse all the blocks folding conditionals with known ranges. */
3555 prop_value_t *single_val_range;
3556 bool do_value_subst_p;
3560 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
3561 dump_all_value_ranges (dump_file);
3562 fprintf (dump_file, "\n");
3565 /* We may have ended with ranges that have exactly one value. Those
3566 values can be substituted as any other copy/const propagated
3567 value using substitute_and_fold. */
3568 single_val_range = xmalloc (num_ssa_names * sizeof (*single_val_range));
3569 memset (single_val_range, 0, num_ssa_names * sizeof (*single_val_range));
3571 do_value_subst_p = false;
3572 for (i = 0; i < num_ssa_names; i++)
3574 && vr_value[i]->type == VR_RANGE
3575 && vr_value[i]->min == vr_value[i]->max)
3577 single_val_range[i].value = vr_value[i]->min;
3578 do_value_subst_p = true;
3581 if (!do_value_subst_p)
3583 /* We found no single-valued ranges, don't waste time trying to
3584 do single value substitution in substitute_and_fold. */
3585 free (single_val_range);
3586 single_val_range = NULL;
3589 substitute_and_fold (single_val_range, true);
3591 /* One could argue all simplifications should be done here
3592 rather than using substitute_and_fold since this code
3593 is going to have to perform a complete walk through the
3595 simplify_using_ranges ();
3597 /* Free allocated memory. */
3598 for (i = 0; i < num_ssa_names; i++)
3601 BITMAP_FREE (vr_value[i]->equiv);
3605 free (single_val_range);
3610 /* Main entry point to VRP (Value Range Propagation). This pass is
3611 loosely based on J. R. C. Patterson, ``Accurate Static Branch
3612 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
3613 Programming Language Design and Implementation, pp. 67-78, 1995.
3614 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
3616 This is essentially an SSA-CCP pass modified to deal with ranges
3617 instead of constants.
3619 While propagating ranges, we may find that two or more SSA name
3620 have equivalent, though distinct ranges. For instance,
3623 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
3625 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
3629 In the code above, pointer p_5 has range [q_2, q_2], but from the
3630 code we can also determine that p_5 cannot be NULL and, if q_2 had
3631 a non-varying range, p_5's range should also be compatible with it.
3633 These equivalences are created by two expressions: ASSERT_EXPR and
3634 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
3635 result of another assertion, then we can use the fact that p_5 and
3636 p_4 are equivalent when evaluating p_5's range.
3638 Together with value ranges, we also propagate these equivalences
3639 between names so that we can take advantage of information from
3640 multiple ranges when doing final replacement. Note that this
3641 equivalency relation is transitive but not symmetric.
3643 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
3644 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
3645 in contexts where that assertion does not hold (e.g., in line 6).
3647 TODO, the main difference between this pass and Patterson's is that
3648 we do not propagate edge probabilities. We only compute whether
3649 edges can be taken or not. That is, instead of having a spectrum
3650 of jump probabilities between 0 and 1, we only deal with 0, 1 and
3651 DON'T KNOW. In the future, it may be worthwhile to propagate
3652 probabilities to aid branch prediction. */
3657 insert_range_assertions ();
3659 cfg_loops = loop_optimizer_init (NULL);
3661 scev_initialize (cfg_loops);
3664 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
3670 loop_optimizer_finalize (cfg_loops, NULL);
3671 current_loops = NULL;
3674 remove_range_assertions ();
3680 return flag_tree_vrp != 0;
3683 struct tree_opt_pass pass_vrp =
3686 gate_vrp, /* gate */
3687 execute_vrp, /* execute */
3690 0, /* static_pass_number */
3691 TV_TREE_VRP, /* tv_id */
3692 PROP_ssa | PROP_alias, /* properties_required */
3693 0, /* properties_provided */
3694 0, /* properties_destroyed */
3695 0, /* todo_flags_start */
3700 | TODO_update_ssa, /* todo_flags_finish */