1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005, 2006 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
24 #include "coretypes.h"
29 #include "basic-block.h"
30 #include "tree-flow.h"
31 #include "tree-pass.h"
32 #include "tree-dump.h"
34 #include "diagnostic.h"
37 #include "tree-scalar-evolution.h"
38 #include "tree-ssa-propagate.h"
39 #include "tree-chrec.h"
41 /* Set of SSA names found during the dominator traversal of a
42 sub-graph in find_assert_locations. */
43 static sbitmap found_in_subgraph;
45 /* Local functions. */
46 static int compare_values (tree val1, tree val2);
47 static void vrp_meet (value_range_t *, value_range_t *);
49 /* Location information for ASSERT_EXPRs. Each instance of this
50 structure describes an ASSERT_EXPR for an SSA name. Since a single
51 SSA name may have more than one assertion associated with it, these
52 locations are kept in a linked list attached to the corresponding
56 /* Basic block where the assertion would be inserted. */
59 /* Some assertions need to be inserted on an edge (e.g., assertions
60 generated by COND_EXPRs). In those cases, BB will be NULL. */
63 /* Pointer to the statement that generated this assertion. */
64 block_stmt_iterator si;
66 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
67 enum tree_code comp_code;
69 /* Value being compared against. */
72 /* Next node in the linked list. */
73 struct assert_locus_d *next;
76 typedef struct assert_locus_d *assert_locus_t;
78 /* If bit I is present, it means that SSA name N_i has a list of
79 assertions that should be inserted in the IL. */
80 static bitmap need_assert_for;
82 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
83 holds a list of ASSERT_LOCUS_T nodes that describe where
84 ASSERT_EXPRs for SSA name N_I should be inserted. */
85 static assert_locus_t *asserts_for;
87 /* Set of blocks visited in find_assert_locations. Used to avoid
88 visiting the same block more than once. */
89 static sbitmap blocks_visited;
91 /* Value range array. After propagation, VR_VALUE[I] holds the range
92 of values that SSA name N_I may take. */
93 static value_range_t **vr_value;
96 /* Return true if ARG is marked with the nonnull attribute in the
97 current function signature. */
100 nonnull_arg_p (tree arg)
102 tree t, attrs, fntype;
103 unsigned HOST_WIDE_INT arg_num;
105 gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
107 /* The static chain decl is always non null. */
108 if (arg == cfun->static_chain_decl)
111 fntype = TREE_TYPE (current_function_decl);
112 attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype));
114 /* If "nonnull" wasn't specified, we know nothing about the argument. */
115 if (attrs == NULL_TREE)
118 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
119 if (TREE_VALUE (attrs) == NULL_TREE)
122 /* Get the position number for ARG in the function signature. */
123 for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl);
125 t = TREE_CHAIN (t), arg_num++)
131 gcc_assert (t == arg);
133 /* Now see if ARG_NUM is mentioned in the nonnull list. */
134 for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
136 if (compare_tree_int (TREE_VALUE (t), arg_num) == 0)
144 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
147 set_value_range (value_range_t *vr, enum value_range_type t, tree min,
148 tree max, bitmap equiv)
150 #if defined ENABLE_CHECKING
151 /* Check the validity of the range. */
152 if (t == VR_RANGE || t == VR_ANTI_RANGE)
156 gcc_assert (min && max);
158 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
159 gcc_assert (min != TYPE_MIN_VALUE (TREE_TYPE (min))
160 || max != TYPE_MAX_VALUE (TREE_TYPE (max)));
162 cmp = compare_values (min, max);
163 gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
166 if (t == VR_UNDEFINED || t == VR_VARYING)
167 gcc_assert (min == NULL_TREE && max == NULL_TREE);
169 if (t == VR_UNDEFINED || t == VR_VARYING)
170 gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
177 /* Since updating the equivalence set involves deep copying the
178 bitmaps, only do it if absolutely necessary. */
179 if (vr->equiv == NULL)
180 vr->equiv = BITMAP_ALLOC (NULL);
182 if (equiv != vr->equiv)
184 if (equiv && !bitmap_empty_p (equiv))
185 bitmap_copy (vr->equiv, equiv);
187 bitmap_clear (vr->equiv);
192 /* Copy value range FROM into value range TO. */
195 copy_value_range (value_range_t *to, value_range_t *from)
197 set_value_range (to, from->type, from->min, from->max, from->equiv);
200 /* Set value range VR to a non-negative range of type TYPE. */
203 set_value_range_to_nonnegative (value_range_t *vr, tree type)
205 tree zero = build_int_cst (type, 0);
206 set_value_range (vr, VR_RANGE, zero, TYPE_MAX_VALUE (type), vr->equiv);
209 /* Set value range VR to a non-NULL range of type TYPE. */
212 set_value_range_to_nonnull (value_range_t *vr, tree type)
214 tree zero = build_int_cst (type, 0);
215 set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
219 /* Set value range VR to a NULL range of type TYPE. */
222 set_value_range_to_null (value_range_t *vr, tree type)
224 tree zero = build_int_cst (type, 0);
225 set_value_range (vr, VR_RANGE, zero, zero, vr->equiv);
229 /* Set value range VR to VR_VARYING. */
232 set_value_range_to_varying (value_range_t *vr)
234 vr->type = VR_VARYING;
235 vr->min = vr->max = NULL_TREE;
237 bitmap_clear (vr->equiv);
241 /* Set value range VR to a range of a truthvalue of type TYPE. */
244 set_value_range_to_truthvalue (value_range_t *vr, tree type)
246 if (TYPE_PRECISION (type) == 1)
247 set_value_range_to_varying (vr);
249 set_value_range (vr, VR_RANGE,
250 build_int_cst (type, 0), build_int_cst (type, 1),
255 /* Set value range VR to VR_UNDEFINED. */
258 set_value_range_to_undefined (value_range_t *vr)
260 vr->type = VR_UNDEFINED;
261 vr->min = vr->max = NULL_TREE;
263 bitmap_clear (vr->equiv);
267 /* Return value range information for VAR.
269 If we have no values ranges recorded (ie, VRP is not running), then
270 return NULL. Otherwise create an empty range if none existed for VAR. */
272 static value_range_t *
273 get_value_range (tree var)
277 unsigned ver = SSA_NAME_VERSION (var);
279 /* If we have no recorded ranges, then return NULL. */
287 /* Create a default value range. */
288 vr_value[ver] = vr = XCNEW (value_range_t);
290 /* Allocate an equivalence set. */
291 vr->equiv = BITMAP_ALLOC (NULL);
293 /* If VAR is a default definition, the variable can take any value
295 sym = SSA_NAME_VAR (var);
296 if (SSA_NAME_IS_DEFAULT_DEF (var))
298 /* Try to use the "nonnull" attribute to create ~[0, 0]
299 anti-ranges for pointers. Note that this is only valid with
300 default definitions of PARM_DECLs. */
301 if (TREE_CODE (sym) == PARM_DECL
302 && POINTER_TYPE_P (TREE_TYPE (sym))
303 && nonnull_arg_p (sym))
304 set_value_range_to_nonnull (vr, TREE_TYPE (sym));
306 set_value_range_to_varying (vr);
312 /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */
315 vrp_operand_equal_p (tree val1, tree val2)
319 && operand_equal_p (val1, val2, 0)));
322 /* Return true, if the bitmaps B1 and B2 are equal. */
325 vrp_bitmap_equal_p (bitmap b1, bitmap b2)
329 && bitmap_equal_p (b1, b2)));
332 /* Update the value range and equivalence set for variable VAR to
333 NEW_VR. Return true if NEW_VR is different from VAR's previous
336 NOTE: This function assumes that NEW_VR is a temporary value range
337 object created for the sole purpose of updating VAR's range. The
338 storage used by the equivalence set from NEW_VR will be freed by
339 this function. Do not call update_value_range when NEW_VR
340 is the range object associated with another SSA name. */
343 update_value_range (tree var, value_range_t *new_vr)
345 value_range_t *old_vr;
348 /* Update the value range, if necessary. */
349 old_vr = get_value_range (var);
350 is_new = old_vr->type != new_vr->type
351 || !vrp_operand_equal_p (old_vr->min, new_vr->min)
352 || !vrp_operand_equal_p (old_vr->max, new_vr->max)
353 || !vrp_bitmap_equal_p (old_vr->equiv, new_vr->equiv);
356 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
359 BITMAP_FREE (new_vr->equiv);
360 new_vr->equiv = NULL;
366 /* Add VAR and VAR's equivalence set to EQUIV. */
369 add_equivalence (bitmap equiv, tree var)
371 unsigned ver = SSA_NAME_VERSION (var);
372 value_range_t *vr = vr_value[ver];
374 bitmap_set_bit (equiv, ver);
376 bitmap_ior_into (equiv, vr->equiv);
380 /* Return true if VR is ~[0, 0]. */
383 range_is_nonnull (value_range_t *vr)
385 return vr->type == VR_ANTI_RANGE
386 && integer_zerop (vr->min)
387 && integer_zerop (vr->max);
391 /* Return true if VR is [0, 0]. */
394 range_is_null (value_range_t *vr)
396 return vr->type == VR_RANGE
397 && integer_zerop (vr->min)
398 && integer_zerop (vr->max);
402 /* Return true if value range VR involves at least one symbol. */
405 symbolic_range_p (value_range_t *vr)
407 return (!is_gimple_min_invariant (vr->min)
408 || !is_gimple_min_invariant (vr->max));
411 /* Like tree_expr_nonnegative_p, but this function uses value ranges
415 vrp_expr_computes_nonnegative (tree expr)
417 return tree_expr_nonnegative_p (expr);
420 /* Like tree_expr_nonzero_p, but this function uses value ranges
424 vrp_expr_computes_nonzero (tree expr)
426 if (tree_expr_nonzero_p (expr))
429 /* If we have an expression of the form &X->a, then the expression
430 is nonnull if X is nonnull. */
431 if (TREE_CODE (expr) == ADDR_EXPR)
433 tree base = get_base_address (TREE_OPERAND (expr, 0));
435 if (base != NULL_TREE
436 && TREE_CODE (base) == INDIRECT_REF
437 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
439 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
440 if (range_is_nonnull (vr))
448 /* Returns true if EXPR is a valid value (as expected by compare_values) --
449 a gimple invariant, or SSA_NAME +- CST. */
452 valid_value_p (tree expr)
454 if (TREE_CODE (expr) == SSA_NAME)
457 if (TREE_CODE (expr) == PLUS_EXPR
458 || TREE_CODE (expr) == MINUS_EXPR)
459 return (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME
460 && TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST);
462 return is_gimple_min_invariant (expr);
468 -2 if those are incomparable. */
470 operand_less_p (tree val, tree val2)
473 /* LT is folded faster than GE and others. Inline the common case. */
474 if (TREE_CODE (val) == INTEGER_CST && TREE_CODE (val2) == INTEGER_CST)
476 if (TYPE_UNSIGNED (TREE_TYPE (val)))
477 return INT_CST_LT_UNSIGNED (val, val2);
479 return INT_CST_LT (val, val2);
482 tcmp = fold_binary_to_constant (LT_EXPR, boolean_type_node, val, val2);
485 return !integer_zerop (tcmp);
488 /* Compare two values VAL1 and VAL2. Return
490 -2 if VAL1 and VAL2 cannot be compared at compile-time,
493 +1 if VAL1 > VAL2, and
496 This is similar to tree_int_cst_compare but supports pointer values
497 and values that cannot be compared at compile time. */
500 compare_values (tree val1, tree val2)
505 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
507 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
508 == POINTER_TYPE_P (TREE_TYPE (val2)));
510 if ((TREE_CODE (val1) == SSA_NAME
511 || TREE_CODE (val1) == PLUS_EXPR
512 || TREE_CODE (val1) == MINUS_EXPR)
513 && (TREE_CODE (val2) == SSA_NAME
514 || TREE_CODE (val2) == PLUS_EXPR
515 || TREE_CODE (val2) == MINUS_EXPR))
518 enum tree_code code1, code2;
520 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
521 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
522 same name, return -2. */
523 if (TREE_CODE (val1) == SSA_NAME)
531 code1 = TREE_CODE (val1);
532 n1 = TREE_OPERAND (val1, 0);
533 c1 = TREE_OPERAND (val1, 1);
534 if (tree_int_cst_sgn (c1) == -1)
536 c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1);
539 code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
543 if (TREE_CODE (val2) == SSA_NAME)
551 code2 = TREE_CODE (val2);
552 n2 = TREE_OPERAND (val2, 0);
553 c2 = TREE_OPERAND (val2, 1);
554 if (tree_int_cst_sgn (c2) == -1)
556 c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2);
559 code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
563 /* Both values must use the same name. */
567 if (code1 == SSA_NAME
568 && code2 == SSA_NAME)
572 /* If overflow is defined we cannot simplify more. */
573 if (TYPE_UNSIGNED (TREE_TYPE (val1))
577 if (code1 == SSA_NAME)
579 if (code2 == PLUS_EXPR)
580 /* NAME < NAME + CST */
582 else if (code2 == MINUS_EXPR)
583 /* NAME > NAME - CST */
586 else if (code1 == PLUS_EXPR)
588 if (code2 == SSA_NAME)
589 /* NAME + CST > NAME */
591 else if (code2 == PLUS_EXPR)
592 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
593 return compare_values (c1, c2);
594 else if (code2 == MINUS_EXPR)
595 /* NAME + CST1 > NAME - CST2 */
598 else if (code1 == MINUS_EXPR)
600 if (code2 == SSA_NAME)
601 /* NAME - CST < NAME */
603 else if (code2 == PLUS_EXPR)
604 /* NAME - CST1 < NAME + CST2 */
606 else if (code2 == MINUS_EXPR)
607 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
608 C1 and C2 are swapped in the call to compare_values. */
609 return compare_values (c2, c1);
615 /* We cannot compare non-constants. */
616 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
619 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
621 /* We cannot compare overflowed values. */
622 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
625 return tree_int_cst_compare (val1, val2);
631 /* First see if VAL1 and VAL2 are not the same. */
632 if (val1 == val2 || operand_equal_p (val1, val2, 0))
635 /* If VAL1 is a lower address than VAL2, return -1. */
636 if (operand_less_p (val1, val2) == 1)
639 /* If VAL1 is a higher address than VAL2, return +1. */
640 if (operand_less_p (val2, val1) == 1)
643 /* If VAL1 is different than VAL2, return +2.
644 For integer constants we either have already returned -1 or 1
645 or they are equivalent. We still might succeed in proving
646 something about non-trivial operands. */
647 if (TREE_CODE (val1) != INTEGER_CST
648 || TREE_CODE (val2) != INTEGER_CST)
650 t = fold_binary_to_constant (NE_EXPR, boolean_type_node, val1, val2);
651 if (t && tree_expr_nonzero_p (t))
660 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
661 0 if VAL is not inside VR,
662 -2 if we cannot tell either way.
664 FIXME, the current semantics of this functions are a bit quirky
665 when taken in the context of VRP. In here we do not care
666 about VR's type. If VR is the anti-range ~[3, 5] the call
667 value_inside_range (4, VR) will return 1.
669 This is counter-intuitive in a strict sense, but the callers
670 currently expect this. They are calling the function
671 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
672 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
675 This also applies to value_ranges_intersect_p and
676 range_includes_zero_p. The semantics of VR_RANGE and
677 VR_ANTI_RANGE should be encoded here, but that also means
678 adapting the users of these functions to the new semantics.
680 Benchmark compile/20001226-1.c compilation time after changing this
684 value_inside_range (tree val, value_range_t * vr)
688 cmp1 = operand_less_p (val, vr->min);
694 cmp2 = operand_less_p (vr->max, val);
702 /* Return true if value ranges VR0 and VR1 have a non-empty
705 Benchmark compile/20001226-1.c compilation time after changing this
710 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
712 /* The value ranges do not intersect if the maximum of the first range is
713 less than the minimum of the second range or vice versa.
714 When those relations are unknown, we can't do any better. */
715 if (operand_less_p (vr0->max, vr1->min) != 0)
717 if (operand_less_p (vr1->max, vr0->min) != 0)
723 /* Return true if VR includes the value zero, false otherwise. FIXME,
724 currently this will return false for an anti-range like ~[-4, 3].
725 This will be wrong when the semantics of value_inside_range are
726 modified (currently the users of this function expect these
730 range_includes_zero_p (value_range_t *vr)
734 gcc_assert (vr->type != VR_UNDEFINED
735 && vr->type != VR_VARYING
736 && !symbolic_range_p (vr));
738 zero = build_int_cst (TREE_TYPE (vr->min), 0);
739 return (value_inside_range (zero, vr) == 1);
742 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
743 false otherwise or if no value range information is available. */
746 ssa_name_nonnegative_p (tree t)
748 value_range_t *vr = get_value_range (t);
753 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
754 which would return a useful value should be encoded as a VR_RANGE. */
755 if (vr->type == VR_RANGE)
757 int result = compare_values (vr->min, integer_zero_node);
759 return (result == 0 || result == 1);
764 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
765 false otherwise or if no value range information is available. */
768 ssa_name_nonzero_p (tree t)
770 value_range_t *vr = get_value_range (t);
775 /* A VR_RANGE which does not include zero is a nonzero value. */
776 if (vr->type == VR_RANGE && !symbolic_range_p (vr))
777 return ! range_includes_zero_p (vr);
779 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
780 if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr))
781 return range_includes_zero_p (vr);
787 /* Extract value range information from an ASSERT_EXPR EXPR and store
791 extract_range_from_assert (value_range_t *vr_p, tree expr)
793 tree var, cond, limit, min, max, type;
794 value_range_t *var_vr, *limit_vr;
795 enum tree_code cond_code;
797 var = ASSERT_EXPR_VAR (expr);
798 cond = ASSERT_EXPR_COND (expr);
800 gcc_assert (COMPARISON_CLASS_P (cond));
802 /* Find VAR in the ASSERT_EXPR conditional. */
803 if (var == TREE_OPERAND (cond, 0))
805 /* If the predicate is of the form VAR COMP LIMIT, then we just
806 take LIMIT from the RHS and use the same comparison code. */
807 limit = TREE_OPERAND (cond, 1);
808 cond_code = TREE_CODE (cond);
812 /* If the predicate is of the form LIMIT COMP VAR, then we need
813 to flip around the comparison code to create the proper range
815 limit = TREE_OPERAND (cond, 0);
816 cond_code = swap_tree_comparison (TREE_CODE (cond));
819 type = TREE_TYPE (limit);
820 gcc_assert (limit != var);
822 /* For pointer arithmetic, we only keep track of pointer equality
824 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
826 set_value_range_to_varying (vr_p);
830 /* If LIMIT is another SSA name and LIMIT has a range of its own,
831 try to use LIMIT's range to avoid creating symbolic ranges
833 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
835 /* LIMIT's range is only interesting if it has any useful information. */
837 && (limit_vr->type == VR_UNDEFINED
838 || limit_vr->type == VR_VARYING
839 || symbolic_range_p (limit_vr)))
842 /* Initially, the new range has the same set of equivalences of
843 VAR's range. This will be revised before returning the final
844 value. Since assertions may be chained via mutually exclusive
845 predicates, we will need to trim the set of equivalences before
847 gcc_assert (vr_p->equiv == NULL);
848 vr_p->equiv = BITMAP_ALLOC (NULL);
849 add_equivalence (vr_p->equiv, var);
851 /* Extract a new range based on the asserted comparison for VAR and
852 LIMIT's value range. Notice that if LIMIT has an anti-range, we
853 will only use it for equality comparisons (EQ_EXPR). For any
854 other kind of assertion, we cannot derive a range from LIMIT's
855 anti-range that can be used to describe the new range. For
856 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
857 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
858 no single range for x_2 that could describe LE_EXPR, so we might
859 as well build the range [b_4, +INF] for it. */
860 if (cond_code == EQ_EXPR)
862 enum value_range_type range_type;
866 range_type = limit_vr->type;
872 range_type = VR_RANGE;
877 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
879 /* When asserting the equality VAR == LIMIT and LIMIT is another
880 SSA name, the new range will also inherit the equivalence set
882 if (TREE_CODE (limit) == SSA_NAME)
883 add_equivalence (vr_p->equiv, limit);
885 else if (cond_code == NE_EXPR)
887 /* As described above, when LIMIT's range is an anti-range and
888 this assertion is an inequality (NE_EXPR), then we cannot
889 derive anything from the anti-range. For instance, if
890 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
891 not imply that VAR's range is [0, 0]. So, in the case of
892 anti-ranges, we just assert the inequality using LIMIT and
895 If LIMIT_VR is a range, we can only use it to build a new
896 anti-range if LIMIT_VR is a single-valued range. For
897 instance, if LIMIT_VR is [0, 1], the predicate
898 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
899 Rather, it means that for value 0 VAR should be ~[0, 0]
900 and for value 1, VAR should be ~[1, 1]. We cannot
901 represent these ranges.
903 The only situation in which we can build a valid
904 anti-range is when LIMIT_VR is a single-valued range
905 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
906 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
908 && limit_vr->type == VR_RANGE
909 && compare_values (limit_vr->min, limit_vr->max) == 0)
916 /* In any other case, we cannot use LIMIT's range to build a
921 /* If MIN and MAX cover the whole range for their type, then
922 just use the original LIMIT. */
923 if (INTEGRAL_TYPE_P (type)
924 && min == TYPE_MIN_VALUE (type)
925 && max == TYPE_MAX_VALUE (type))
928 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
930 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
932 min = TYPE_MIN_VALUE (type);
934 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
938 /* If LIMIT_VR is of the form [N1, N2], we need to build the
939 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
944 /* If the maximum value forces us to be out of bounds, simply punt.
945 It would be pointless to try and do anything more since this
946 all should be optimized away above us. */
947 if (cond_code == LT_EXPR && compare_values (max, min) == 0)
948 set_value_range_to_varying (vr_p);
951 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
952 if (cond_code == LT_EXPR)
954 tree one = build_int_cst (type, 1);
955 max = fold_build2 (MINUS_EXPR, type, max, one);
958 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
961 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
963 max = TYPE_MAX_VALUE (type);
965 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
969 /* If LIMIT_VR is of the form [N1, N2], we need to build the
970 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
975 /* If the minimum value forces us to be out of bounds, simply punt.
976 It would be pointless to try and do anything more since this
977 all should be optimized away above us. */
978 if (cond_code == GT_EXPR && compare_values (min, max) == 0)
979 set_value_range_to_varying (vr_p);
982 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
983 if (cond_code == GT_EXPR)
985 tree one = build_int_cst (type, 1);
986 min = fold_build2 (PLUS_EXPR, type, min, one);
989 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
995 /* If VAR already had a known range, it may happen that the new
996 range we have computed and VAR's range are not compatible. For
1000 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
1002 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
1004 While the above comes from a faulty program, it will cause an ICE
1005 later because p_8 and p_6 will have incompatible ranges and at
1006 the same time will be considered equivalent. A similar situation
1010 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
1012 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
1014 Again i_6 and i_7 will have incompatible ranges. It would be
1015 pointless to try and do anything with i_7's range because
1016 anything dominated by 'if (i_5 < 5)' will be optimized away.
1017 Note, due to the wa in which simulation proceeds, the statement
1018 i_7 = ASSERT_EXPR <...> we would never be visited because the
1019 conditional 'if (i_5 < 5)' always evaluates to false. However,
1020 this extra check does not hurt and may protect against future
1021 changes to VRP that may get into a situation similar to the
1022 NULL pointer dereference example.
1024 Note that these compatibility tests are only needed when dealing
1025 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1026 are both anti-ranges, they will always be compatible, because two
1027 anti-ranges will always have a non-empty intersection. */
1029 var_vr = get_value_range (var);
1031 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1032 ranges or anti-ranges. */
1033 if (vr_p->type == VR_VARYING
1034 || vr_p->type == VR_UNDEFINED
1035 || var_vr->type == VR_VARYING
1036 || var_vr->type == VR_UNDEFINED
1037 || symbolic_range_p (vr_p)
1038 || symbolic_range_p (var_vr))
1041 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
1043 /* If the two ranges have a non-empty intersection, we can
1044 refine the resulting range. Since the assert expression
1045 creates an equivalency and at the same time it asserts a
1046 predicate, we can take the intersection of the two ranges to
1047 get better precision. */
1048 if (value_ranges_intersect_p (var_vr, vr_p))
1050 /* Use the larger of the two minimums. */
1051 if (compare_values (vr_p->min, var_vr->min) == -1)
1056 /* Use the smaller of the two maximums. */
1057 if (compare_values (vr_p->max, var_vr->max) == 1)
1062 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
1066 /* The two ranges do not intersect, set the new range to
1067 VARYING, because we will not be able to do anything
1068 meaningful with it. */
1069 set_value_range_to_varying (vr_p);
1072 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
1073 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
1075 /* A range and an anti-range will cancel each other only if
1076 their ends are the same. For instance, in the example above,
1077 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1078 so VR_P should be set to VR_VARYING. */
1079 if (compare_values (var_vr->min, vr_p->min) == 0
1080 && compare_values (var_vr->max, vr_p->max) == 0)
1081 set_value_range_to_varying (vr_p);
1084 tree min, max, anti_min, anti_max, real_min, real_max;
1087 /* We want to compute the logical AND of the two ranges;
1088 there are three cases to consider.
1091 1. The VR_ANTI_RANGE range is completely within the
1092 VR_RANGE and the endpoints of the ranges are
1093 different. In that case the resulting range
1094 should be whichever range is more precise.
1095 Typically that will be the VR_RANGE.
1097 2. The VR_ANTI_RANGE is completely disjoint from
1098 the VR_RANGE. In this case the resulting range
1099 should be the VR_RANGE.
1101 3. There is some overlap between the VR_ANTI_RANGE
1104 3a. If the high limit of the VR_ANTI_RANGE resides
1105 within the VR_RANGE, then the result is a new
1106 VR_RANGE starting at the high limit of the
1107 the VR_ANTI_RANGE + 1 and extending to the
1108 high limit of the original VR_RANGE.
1110 3b. If the low limit of the VR_ANTI_RANGE resides
1111 within the VR_RANGE, then the result is a new
1112 VR_RANGE starting at the low limit of the original
1113 VR_RANGE and extending to the low limit of the
1114 VR_ANTI_RANGE - 1. */
1115 if (vr_p->type == VR_ANTI_RANGE)
1117 anti_min = vr_p->min;
1118 anti_max = vr_p->max;
1119 real_min = var_vr->min;
1120 real_max = var_vr->max;
1124 anti_min = var_vr->min;
1125 anti_max = var_vr->max;
1126 real_min = vr_p->min;
1127 real_max = vr_p->max;
1131 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1132 not including any endpoints. */
1133 if (compare_values (anti_max, real_max) == -1
1134 && compare_values (anti_min, real_min) == 1)
1136 set_value_range (vr_p, VR_RANGE, real_min,
1137 real_max, vr_p->equiv);
1139 /* Case 2, VR_ANTI_RANGE completely disjoint from
1141 else if (compare_values (anti_min, real_max) == 1
1142 || compare_values (anti_max, real_min) == -1)
1144 set_value_range (vr_p, VR_RANGE, real_min,
1145 real_max, vr_p->equiv);
1147 /* Case 3a, the anti-range extends into the low
1148 part of the real range. Thus creating a new
1149 low for the real range. */
1150 else if (((cmp = compare_values (anti_max, real_min)) == 1
1152 && compare_values (anti_max, real_max) == -1)
1154 min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min),
1156 build_int_cst (TREE_TYPE (var_vr->min), 1));
1158 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1160 /* Case 3b, the anti-range extends into the high
1161 part of the real range. Thus creating a new
1162 higher for the real range. */
1163 else if (compare_values (anti_min, real_min) == 1
1164 && ((cmp = compare_values (anti_min, real_max)) == -1
1167 max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min),
1169 build_int_cst (TREE_TYPE (var_vr->min), 1));
1171 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1178 /* Extract range information from SSA name VAR and store it in VR. If
1179 VAR has an interesting range, use it. Otherwise, create the
1180 range [VAR, VAR] and return it. This is useful in situations where
1181 we may have conditionals testing values of VARYING names. For
1188 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1192 extract_range_from_ssa_name (value_range_t *vr, tree var)
1194 value_range_t *var_vr = get_value_range (var);
1196 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
1197 copy_value_range (vr, var_vr);
1199 set_value_range (vr, VR_RANGE, var, var, NULL);
1201 add_equivalence (vr->equiv, var);
1205 /* Wrapper around int_const_binop. If the operation overflows and we
1206 are not using wrapping arithmetic, then adjust the result to be
1207 -INF or +INF depending on CODE, VAL1 and VAL2. */
1210 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
1214 res = int_const_binop (code, val1, val2, 0);
1216 /* If we are not using wrapping arithmetic, operate symbolically
1217 on -INF and +INF. */
1218 if (TYPE_UNSIGNED (TREE_TYPE (val1))
1221 int checkz = compare_values (res, val1);
1222 bool overflow = false;
1224 /* Ensure that res = val1 [+*] val2 >= val1
1225 or that res = val1 - val2 <= val1. */
1226 if ((code == PLUS_EXPR
1227 && !(checkz == 1 || checkz == 0))
1228 || (code == MINUS_EXPR
1229 && !(checkz == 0 || checkz == -1)))
1233 /* Checking for multiplication overflow is done by dividing the
1234 output of the multiplication by the first input of the
1235 multiplication. If the result of that division operation is
1236 not equal to the second input of the multiplication, then the
1237 multiplication overflowed. */
1238 else if (code == MULT_EXPR && !integer_zerop (val1))
1240 tree tmp = int_const_binop (TRUNC_DIV_EXPR,
1243 int check = compare_values (tmp, val2);
1251 res = copy_node (res);
1252 TREE_OVERFLOW (res) = 1;
1256 else if (TREE_OVERFLOW (res)
1257 && !TREE_OVERFLOW (val1)
1258 && !TREE_OVERFLOW (val2))
1260 /* If the operation overflowed but neither VAL1 nor VAL2 are
1261 overflown, return -INF or +INF depending on the operation
1262 and the combination of signs of the operands. */
1263 int sgn1 = tree_int_cst_sgn (val1);
1264 int sgn2 = tree_int_cst_sgn (val2);
1266 /* Notice that we only need to handle the restricted set of
1267 operations handled by extract_range_from_binary_expr.
1268 Among them, only multiplication, addition and subtraction
1269 can yield overflow without overflown operands because we
1270 are working with integral types only... except in the
1271 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1272 for division too. */
1274 /* For multiplication, the sign of the overflow is given
1275 by the comparison of the signs of the operands. */
1276 if ((code == MULT_EXPR && sgn1 == sgn2)
1277 /* For addition, the operands must be of the same sign
1278 to yield an overflow. Its sign is therefore that
1279 of one of the operands, for example the first. */
1280 || (code == PLUS_EXPR && sgn1 > 0)
1281 /* For subtraction, the operands must be of different
1282 signs to yield an overflow. Its sign is therefore
1283 that of the first operand or the opposite of that
1284 of the second operand. A first operand of 0 counts
1285 as positive here, for the corner case 0 - (-INF),
1286 which overflows, but must yield +INF. */
1287 || (code == MINUS_EXPR && sgn1 >= 0)
1288 /* For division, the only case is -INF / -1 = +INF. */
1289 || code == TRUNC_DIV_EXPR
1290 || code == FLOOR_DIV_EXPR
1291 || code == CEIL_DIV_EXPR
1292 || code == EXACT_DIV_EXPR
1293 || code == ROUND_DIV_EXPR)
1294 return TYPE_MAX_VALUE (TREE_TYPE (res));
1296 return TYPE_MIN_VALUE (TREE_TYPE (res));
1303 /* Extract range information from a binary expression EXPR based on
1304 the ranges of each of its operands and the expression code. */
1307 extract_range_from_binary_expr (value_range_t *vr, tree expr)
1309 enum tree_code code = TREE_CODE (expr);
1310 enum value_range_type type;
1311 tree op0, op1, min, max;
1313 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1314 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1316 /* Not all binary expressions can be applied to ranges in a
1317 meaningful way. Handle only arithmetic operations. */
1318 if (code != PLUS_EXPR
1319 && code != MINUS_EXPR
1320 && code != MULT_EXPR
1321 && code != TRUNC_DIV_EXPR
1322 && code != FLOOR_DIV_EXPR
1323 && code != CEIL_DIV_EXPR
1324 && code != EXACT_DIV_EXPR
1325 && code != ROUND_DIV_EXPR
1328 && code != BIT_AND_EXPR
1329 && code != TRUTH_ANDIF_EXPR
1330 && code != TRUTH_ORIF_EXPR
1331 && code != TRUTH_AND_EXPR
1332 && code != TRUTH_OR_EXPR)
1334 set_value_range_to_varying (vr);
1338 /* Get value ranges for each operand. For constant operands, create
1339 a new value range with the operand to simplify processing. */
1340 op0 = TREE_OPERAND (expr, 0);
1341 if (TREE_CODE (op0) == SSA_NAME)
1342 vr0 = *(get_value_range (op0));
1343 else if (is_gimple_min_invariant (op0))
1344 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1346 set_value_range_to_varying (&vr0);
1348 op1 = TREE_OPERAND (expr, 1);
1349 if (TREE_CODE (op1) == SSA_NAME)
1350 vr1 = *(get_value_range (op1));
1351 else if (is_gimple_min_invariant (op1))
1352 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1354 set_value_range_to_varying (&vr1);
1356 /* If either range is UNDEFINED, so is the result. */
1357 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1359 set_value_range_to_undefined (vr);
1363 /* The type of the resulting value range defaults to VR0.TYPE. */
1366 /* Refuse to operate on VARYING ranges, ranges of different kinds
1367 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1368 because we may be able to derive a useful range even if one of
1369 the operands is VR_VARYING or symbolic range. TODO, we may be
1370 able to derive anti-ranges in some cases. */
1371 if (code != BIT_AND_EXPR
1372 && code != TRUTH_AND_EXPR
1373 && code != TRUTH_OR_EXPR
1374 && (vr0.type == VR_VARYING
1375 || vr1.type == VR_VARYING
1376 || vr0.type != vr1.type
1377 || symbolic_range_p (&vr0)
1378 || symbolic_range_p (&vr1)))
1380 set_value_range_to_varying (vr);
1384 /* Now evaluate the expression to determine the new range. */
1385 if (POINTER_TYPE_P (TREE_TYPE (expr))
1386 || POINTER_TYPE_P (TREE_TYPE (op0))
1387 || POINTER_TYPE_P (TREE_TYPE (op1)))
1389 /* For pointer types, we are really only interested in asserting
1390 whether the expression evaluates to non-NULL. FIXME, we used
1391 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1392 ivopts is generating expressions with pointer multiplication
1394 if (code == PLUS_EXPR)
1396 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1397 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1398 else if (range_is_null (&vr0) && range_is_null (&vr1))
1399 set_value_range_to_null (vr, TREE_TYPE (expr));
1401 set_value_range_to_varying (vr);
1405 /* Subtracting from a pointer, may yield 0, so just drop the
1406 resulting range to varying. */
1407 set_value_range_to_varying (vr);
1413 /* For integer ranges, apply the operation to each end of the
1414 range and see what we end up with. */
1415 if (code == TRUTH_ANDIF_EXPR
1416 || code == TRUTH_ORIF_EXPR
1417 || code == TRUTH_AND_EXPR
1418 || code == TRUTH_OR_EXPR)
1420 /* If one of the operands is zero, we know that the whole
1421 expression evaluates zero. */
1422 if (code == TRUTH_AND_EXPR
1423 && ((vr0.type == VR_RANGE
1424 && integer_zerop (vr0.min)
1425 && integer_zerop (vr0.max))
1426 || (vr1.type == VR_RANGE
1427 && integer_zerop (vr1.min)
1428 && integer_zerop (vr1.max))))
1431 min = max = build_int_cst (TREE_TYPE (expr), 0);
1433 /* If one of the operands is one, we know that the whole
1434 expression evaluates one. */
1435 else if (code == TRUTH_OR_EXPR
1436 && ((vr0.type == VR_RANGE
1437 && integer_onep (vr0.min)
1438 && integer_onep (vr0.max))
1439 || (vr1.type == VR_RANGE
1440 && integer_onep (vr1.min)
1441 && integer_onep (vr1.max))))
1444 min = max = build_int_cst (TREE_TYPE (expr), 1);
1446 else if (vr0.type != VR_VARYING
1447 && vr1.type != VR_VARYING
1448 && vr0.type == vr1.type
1449 && !symbolic_range_p (&vr0)
1450 && !symbolic_range_p (&vr1))
1452 /* Boolean expressions cannot be folded with int_const_binop. */
1453 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1454 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1458 /* The result of a TRUTH_*_EXPR is always true or false. */
1459 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
1463 else if (code == PLUS_EXPR
1465 || code == MAX_EXPR)
1467 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1468 VR_VARYING. It would take more effort to compute a precise
1469 range for such a case. For example, if we have op0 == 1 and
1470 op1 == -1 with their ranges both being ~[0,0], we would have
1471 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1472 Note that we are guaranteed to have vr0.type == vr1.type at
1474 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1476 set_value_range_to_varying (vr);
1480 /* For operations that make the resulting range directly
1481 proportional to the original ranges, apply the operation to
1482 the same end of each range. */
1483 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1484 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1486 else if (code == MULT_EXPR
1487 || code == TRUNC_DIV_EXPR
1488 || code == FLOOR_DIV_EXPR
1489 || code == CEIL_DIV_EXPR
1490 || code == EXACT_DIV_EXPR
1491 || code == ROUND_DIV_EXPR)
1496 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1497 drop to VR_VARYING. It would take more effort to compute a
1498 precise range for such a case. For example, if we have
1499 op0 == 65536 and op1 == 65536 with their ranges both being
1500 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1501 we cannot claim that the product is in ~[0,0]. Note that we
1502 are guaranteed to have vr0.type == vr1.type at this
1504 if (code == MULT_EXPR
1505 && vr0.type == VR_ANTI_RANGE
1506 && (flag_wrapv || TYPE_UNSIGNED (TREE_TYPE (op0))))
1508 set_value_range_to_varying (vr);
1512 /* Multiplications and divisions are a bit tricky to handle,
1513 depending on the mix of signs we have in the two ranges, we
1514 need to operate on different values to get the minimum and
1515 maximum values for the new range. One approach is to figure
1516 out all the variations of range combinations and do the
1519 However, this involves several calls to compare_values and it
1520 is pretty convoluted. It's simpler to do the 4 operations
1521 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1522 MAX1) and then figure the smallest and largest values to form
1525 /* Divisions by zero result in a VARYING value. */
1526 if (code != MULT_EXPR
1527 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1529 set_value_range_to_varying (vr);
1533 /* Compute the 4 cross operations. */
1534 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1536 val[1] = (vr1.max != vr1.min)
1537 ? vrp_int_const_binop (code, vr0.min, vr1.max)
1540 val[2] = (vr0.max != vr0.min)
1541 ? vrp_int_const_binop (code, vr0.max, vr1.min)
1544 val[3] = (vr0.min != vr0.max && vr1.min != vr1.max)
1545 ? vrp_int_const_binop (code, vr0.max, vr1.max)
1548 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1552 for (i = 1; i < 4; i++)
1554 if (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
1555 || !is_gimple_min_invariant (max) || TREE_OVERFLOW (max))
1560 if (!is_gimple_min_invariant (val[i]) || TREE_OVERFLOW (val[i]))
1562 /* If we found an overflowed value, set MIN and MAX
1563 to it so that we set the resulting range to
1569 if (compare_values (val[i], min) == -1)
1572 if (compare_values (val[i], max) == 1)
1577 else if (code == MINUS_EXPR)
1579 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1580 VR_VARYING. It would take more effort to compute a precise
1581 range for such a case. For example, if we have op0 == 1 and
1582 op1 == 1 with their ranges both being ~[0,0], we would have
1583 op0 - op1 == 0, so we cannot claim that the difference is in
1584 ~[0,0]. Note that we are guaranteed to have
1585 vr0.type == vr1.type at this point. */
1586 if (vr0.type == VR_ANTI_RANGE)
1588 set_value_range_to_varying (vr);
1592 /* For MINUS_EXPR, apply the operation to the opposite ends of
1594 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1595 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1597 else if (code == BIT_AND_EXPR)
1599 if (vr0.type == VR_RANGE
1600 && vr0.min == vr0.max
1601 && tree_expr_nonnegative_p (vr0.max)
1602 && TREE_CODE (vr0.max) == INTEGER_CST)
1604 min = build_int_cst (TREE_TYPE (expr), 0);
1607 else if (vr1.type == VR_RANGE
1608 && vr1.min == vr1.max
1609 && tree_expr_nonnegative_p (vr1.max)
1610 && TREE_CODE (vr1.max) == INTEGER_CST)
1613 min = build_int_cst (TREE_TYPE (expr), 0);
1618 set_value_range_to_varying (vr);
1625 /* If either MIN or MAX overflowed, then set the resulting range to
1627 if (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
1628 || !is_gimple_min_invariant (max) || TREE_OVERFLOW (max))
1630 set_value_range_to_varying (vr);
1634 cmp = compare_values (min, max);
1635 if (cmp == -2 || cmp == 1)
1637 /* If the new range has its limits swapped around (MIN > MAX),
1638 then the operation caused one of them to wrap around, mark
1639 the new range VARYING. */
1640 set_value_range_to_varying (vr);
1643 set_value_range (vr, type, min, max, NULL);
1647 /* Extract range information from a unary expression EXPR based on
1648 the range of its operand and the expression code. */
1651 extract_range_from_unary_expr (value_range_t *vr, tree expr)
1653 enum tree_code code = TREE_CODE (expr);
1656 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1658 /* Refuse to operate on certain unary expressions for which we
1659 cannot easily determine a resulting range. */
1660 if (code == FIX_TRUNC_EXPR
1661 || code == FLOAT_EXPR
1662 || code == BIT_NOT_EXPR
1663 || code == NON_LVALUE_EXPR
1664 || code == CONJ_EXPR)
1666 set_value_range_to_varying (vr);
1670 /* Get value ranges for the operand. For constant operands, create
1671 a new value range with the operand to simplify processing. */
1672 op0 = TREE_OPERAND (expr, 0);
1673 if (TREE_CODE (op0) == SSA_NAME)
1674 vr0 = *(get_value_range (op0));
1675 else if (is_gimple_min_invariant (op0))
1676 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1678 set_value_range_to_varying (&vr0);
1680 /* If VR0 is UNDEFINED, so is the result. */
1681 if (vr0.type == VR_UNDEFINED)
1683 set_value_range_to_undefined (vr);
1687 /* Refuse to operate on symbolic ranges, or if neither operand is
1688 a pointer or integral type. */
1689 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0))
1690 && !POINTER_TYPE_P (TREE_TYPE (op0)))
1691 || (vr0.type != VR_VARYING
1692 && symbolic_range_p (&vr0)))
1694 set_value_range_to_varying (vr);
1698 /* If the expression involves pointers, we are only interested in
1699 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1700 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
1702 if (range_is_nonnull (&vr0) || tree_expr_nonzero_p (expr))
1703 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1704 else if (range_is_null (&vr0))
1705 set_value_range_to_null (vr, TREE_TYPE (expr));
1707 set_value_range_to_varying (vr);
1712 /* Handle unary expressions on integer ranges. */
1713 if (code == NOP_EXPR || code == CONVERT_EXPR)
1715 tree inner_type = TREE_TYPE (op0);
1716 tree outer_type = TREE_TYPE (expr);
1718 /* If VR0 represents a simple range, then try to convert
1719 the min and max values for the range to the same type
1720 as OUTER_TYPE. If the results compare equal to VR0's
1721 min and max values and the new min is still less than
1722 or equal to the new max, then we can safely use the newly
1723 computed range for EXPR. This allows us to compute
1724 accurate ranges through many casts. */
1725 if (vr0.type == VR_RANGE
1726 || (vr0.type == VR_VARYING
1727 && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type)))
1729 tree new_min, new_max, orig_min, orig_max;
1731 /* Convert the input operand min/max to OUTER_TYPE. If
1732 the input has no range information, then use the min/max
1733 for the input's type. */
1734 if (vr0.type == VR_RANGE)
1741 orig_min = TYPE_MIN_VALUE (inner_type);
1742 orig_max = TYPE_MAX_VALUE (inner_type);
1745 new_min = fold_convert (outer_type, orig_min);
1746 new_max = fold_convert (outer_type, orig_max);
1748 /* Verify the new min/max values are gimple values and
1749 that they compare equal to the original input's
1751 if (is_gimple_val (new_min)
1752 && is_gimple_val (new_max)
1753 && tree_int_cst_equal (new_min, orig_min)
1754 && tree_int_cst_equal (new_max, orig_max)
1755 && (cmp = compare_values (new_min, new_max)) <= 0
1758 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
1763 /* When converting types of different sizes, set the result to
1764 VARYING. Things like sign extensions and precision loss may
1765 change the range. For instance, if x_3 is of type 'long long
1766 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1767 is impossible to know at compile time whether y_5 will be
1769 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
1770 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
1772 set_value_range_to_varying (vr);
1777 /* Conversion of a VR_VARYING value to a wider type can result
1778 in a usable range. So wait until after we've handled conversions
1779 before dropping the result to VR_VARYING if we had a source
1780 operand that is VR_VARYING. */
1781 if (vr0.type == VR_VARYING)
1783 set_value_range_to_varying (vr);
1787 /* Apply the operation to each end of the range and see what we end
1789 if (code == NEGATE_EXPR
1790 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1792 /* NEGATE_EXPR flips the range around. We need to treat
1793 TYPE_MIN_VALUE specially dependent on wrapping, range type
1794 and if it was used as minimum or maximum value:
1795 -~[MIN, MIN] == ~[MIN, MIN]
1796 -[MIN, 0] == [0, MAX] for -fno-wrapv
1797 -[MIN, 0] == [0, MIN] for -fwrapv (will be set to varying later) */
1798 min = vr0.max == TYPE_MIN_VALUE (TREE_TYPE (expr))
1799 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1800 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1802 max = vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr))
1803 ? (vr0.type == VR_ANTI_RANGE || flag_wrapv
1804 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1805 : TYPE_MAX_VALUE (TREE_TYPE (expr)))
1806 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1809 else if (code == NEGATE_EXPR
1810 && TYPE_UNSIGNED (TREE_TYPE (expr)))
1812 if (!range_includes_zero_p (&vr0))
1814 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1815 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1819 if (range_is_null (&vr0))
1820 set_value_range_to_null (vr, TREE_TYPE (expr));
1822 set_value_range_to_varying (vr);
1826 else if (code == ABS_EXPR
1827 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1829 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1832 && ((vr0.type == VR_RANGE
1833 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1834 || (vr0.type == VR_ANTI_RANGE
1835 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
1836 && !range_includes_zero_p (&vr0))))
1838 set_value_range_to_varying (vr);
1842 /* ABS_EXPR may flip the range around, if the original range
1843 included negative values. */
1844 min = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1845 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1846 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1848 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1850 cmp = compare_values (min, max);
1852 /* If a VR_ANTI_RANGEs contains zero, then we have
1853 ~[-INF, min(MIN, MAX)]. */
1854 if (vr0.type == VR_ANTI_RANGE)
1856 if (range_includes_zero_p (&vr0))
1858 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
1860 /* Take the lower of the two values. */
1864 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1865 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1866 flag_wrapv is set and the original anti-range doesn't include
1867 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1868 min = (flag_wrapv && vr0.min != type_min_value
1869 ? int_const_binop (PLUS_EXPR,
1871 integer_one_node, 0)
1876 /* All else has failed, so create the range [0, INF], even for
1877 flag_wrapv since TYPE_MIN_VALUE is in the original
1879 vr0.type = VR_RANGE;
1880 min = build_int_cst (TREE_TYPE (expr), 0);
1881 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
1885 /* If the range contains zero then we know that the minimum value in the
1886 range will be zero. */
1887 else if (range_includes_zero_p (&vr0))
1891 min = build_int_cst (TREE_TYPE (expr), 0);
1895 /* If the range was reversed, swap MIN and MAX. */
1906 /* Otherwise, operate on each end of the range. */
1907 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1908 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1911 cmp = compare_values (min, max);
1912 if (cmp == -2 || cmp == 1)
1914 /* If the new range has its limits swapped around (MIN > MAX),
1915 then the operation caused one of them to wrap around, mark
1916 the new range VARYING. */
1917 set_value_range_to_varying (vr);
1920 set_value_range (vr, vr0.type, min, max, NULL);
1924 /* Extract range information from a conditional expression EXPR based on
1925 the ranges of each of its operands and the expression code. */
1928 extract_range_from_cond_expr (value_range_t *vr, tree expr)
1931 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1932 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1934 /* Get value ranges for each operand. For constant operands, create
1935 a new value range with the operand to simplify processing. */
1936 op0 = COND_EXPR_THEN (expr);
1937 if (TREE_CODE (op0) == SSA_NAME)
1938 vr0 = *(get_value_range (op0));
1939 else if (is_gimple_min_invariant (op0))
1940 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1942 set_value_range_to_varying (&vr0);
1944 op1 = COND_EXPR_ELSE (expr);
1945 if (TREE_CODE (op1) == SSA_NAME)
1946 vr1 = *(get_value_range (op1));
1947 else if (is_gimple_min_invariant (op1))
1948 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1950 set_value_range_to_varying (&vr1);
1952 /* The resulting value range is the union of the operand ranges */
1953 vrp_meet (&vr0, &vr1);
1954 copy_value_range (vr, &vr0);
1958 /* Extract range information from a comparison expression EXPR based
1959 on the range of its operand and the expression code. */
1962 extract_range_from_comparison (value_range_t *vr, tree expr)
1964 tree val = vrp_evaluate_conditional (expr, false);
1967 /* Since this expression was found on the RHS of an assignment,
1968 its type may be different from _Bool. Convert VAL to EXPR's
1970 val = fold_convert (TREE_TYPE (expr), val);
1971 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
1974 /* The result of a comparison is always true or false. */
1975 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
1979 /* Try to compute a useful range out of expression EXPR and store it
1983 extract_range_from_expr (value_range_t *vr, tree expr)
1985 enum tree_code code = TREE_CODE (expr);
1987 if (code == ASSERT_EXPR)
1988 extract_range_from_assert (vr, expr);
1989 else if (code == SSA_NAME)
1990 extract_range_from_ssa_name (vr, expr);
1991 else if (TREE_CODE_CLASS (code) == tcc_binary
1992 || code == TRUTH_ANDIF_EXPR
1993 || code == TRUTH_ORIF_EXPR
1994 || code == TRUTH_AND_EXPR
1995 || code == TRUTH_OR_EXPR
1996 || code == TRUTH_XOR_EXPR)
1997 extract_range_from_binary_expr (vr, expr);
1998 else if (TREE_CODE_CLASS (code) == tcc_unary)
1999 extract_range_from_unary_expr (vr, expr);
2000 else if (code == COND_EXPR)
2001 extract_range_from_cond_expr (vr, expr);
2002 else if (TREE_CODE_CLASS (code) == tcc_comparison)
2003 extract_range_from_comparison (vr, expr);
2004 else if (is_gimple_min_invariant (expr))
2005 set_value_range (vr, VR_RANGE, expr, expr, NULL);
2007 set_value_range_to_varying (vr);
2009 /* If we got a varying range from the tests above, try a final
2010 time to derive a nonnegative or nonzero range. This time
2011 relying primarily on generic routines in fold in conjunction
2013 if (vr->type == VR_VARYING)
2015 if (INTEGRAL_TYPE_P (TREE_TYPE (expr))
2016 && vrp_expr_computes_nonnegative (expr))
2017 set_value_range_to_nonnegative (vr, TREE_TYPE (expr));
2018 else if (vrp_expr_computes_nonzero (expr))
2019 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
2023 /* Given a range VR, a LOOP and a variable VAR, determine whether it
2024 would be profitable to adjust VR using scalar evolution information
2025 for VAR. If so, update VR with the new limits. */
2028 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
2031 tree init, step, chrec, tmin, tmax, min, max, type;
2032 enum ev_direction dir;
2034 /* TODO. Don't adjust anti-ranges. An anti-range may provide
2035 better opportunities than a regular range, but I'm not sure. */
2036 if (vr->type == VR_ANTI_RANGE)
2039 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
2040 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
2043 init = initial_condition_in_loop_num (chrec, loop->num);
2044 step = evolution_part_in_loop_num (chrec, loop->num);
2046 /* If STEP is symbolic, we can't know whether INIT will be the
2047 minimum or maximum value in the range. Also, unless INIT is
2048 a simple expression, compare_values and possibly other functions
2049 in tree-vrp won't be able to handle it. */
2050 if (step == NULL_TREE
2051 || !is_gimple_min_invariant (step)
2052 || !valid_value_p (init))
2055 dir = scev_direction (chrec);
2056 if (/* Do not adjust ranges if we do not know whether the iv increases
2057 or decreases, ... */
2058 dir == EV_DIR_UNKNOWN
2059 /* ... or if it may wrap. */
2060 || scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec),
2064 type = TREE_TYPE (var);
2065 if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type))
2066 tmin = lower_bound_in_type (type, type);
2068 tmin = TYPE_MIN_VALUE (type);
2069 if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type))
2070 tmax = upper_bound_in_type (type, type);
2072 tmax = TYPE_MAX_VALUE (type);
2074 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2079 /* For VARYING or UNDEFINED ranges, just about anything we get
2080 from scalar evolutions should be better. */
2082 if (dir == EV_DIR_DECREASES)
2087 /* If we would create an invalid range, then just assume we
2088 know absolutely nothing. This may be over-conservative,
2089 but it's clearly safe, and should happen only in unreachable
2090 parts of code, or for invalid programs. */
2091 if (compare_values (min, max) == 1)
2094 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2096 else if (vr->type == VR_RANGE)
2101 if (dir == EV_DIR_DECREASES)
2103 /* INIT is the maximum value. If INIT is lower than VR->MAX
2104 but no smaller than VR->MIN, set VR->MAX to INIT. */
2105 if (compare_values (init, max) == -1)
2109 /* If we just created an invalid range with the minimum
2110 greater than the maximum, we fail conservatively.
2111 This should happen only in unreachable
2112 parts of code, or for invalid programs. */
2113 if (compare_values (min, max) == 1)
2119 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2120 if (compare_values (init, min) == 1)
2124 /* Again, avoid creating invalid range by failing. */
2125 if (compare_values (min, max) == 1)
2130 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2135 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2137 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2138 all the values in the ranges.
2140 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2142 - Return NULL_TREE if it is not always possible to determine the
2143 value of the comparison. */
2147 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1)
2149 /* VARYING or UNDEFINED ranges cannot be compared. */
2150 if (vr0->type == VR_VARYING
2151 || vr0->type == VR_UNDEFINED
2152 || vr1->type == VR_VARYING
2153 || vr1->type == VR_UNDEFINED)
2156 /* Anti-ranges need to be handled separately. */
2157 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
2159 /* If both are anti-ranges, then we cannot compute any
2161 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
2164 /* These comparisons are never statically computable. */
2171 /* Equality can be computed only between a range and an
2172 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2173 if (vr0->type == VR_RANGE)
2175 /* To simplify processing, make VR0 the anti-range. */
2176 value_range_t *tmp = vr0;
2181 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
2183 if (compare_values (vr0->min, vr1->min) == 0
2184 && compare_values (vr0->max, vr1->max) == 0)
2185 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2190 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2191 operands around and change the comparison code. */
2192 if (comp == GT_EXPR || comp == GE_EXPR)
2195 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
2201 if (comp == EQ_EXPR)
2203 /* Equality may only be computed if both ranges represent
2204 exactly one value. */
2205 if (compare_values (vr0->min, vr0->max) == 0
2206 && compare_values (vr1->min, vr1->max) == 0)
2208 int cmp_min = compare_values (vr0->min, vr1->min);
2209 int cmp_max = compare_values (vr0->max, vr1->max);
2210 if (cmp_min == 0 && cmp_max == 0)
2211 return boolean_true_node;
2212 else if (cmp_min != -2 && cmp_max != -2)
2213 return boolean_false_node;
2215 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2216 else if (compare_values (vr0->min, vr1->max) == 1
2217 || compare_values (vr1->min, vr0->max) == 1)
2218 return boolean_false_node;
2222 else if (comp == NE_EXPR)
2226 /* If VR0 is completely to the left or completely to the right
2227 of VR1, they are always different. Notice that we need to
2228 make sure that both comparisons yield similar results to
2229 avoid comparing values that cannot be compared at
2231 cmp1 = compare_values (vr0->max, vr1->min);
2232 cmp2 = compare_values (vr0->min, vr1->max);
2233 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
2234 return boolean_true_node;
2236 /* If VR0 and VR1 represent a single value and are identical,
2238 else if (compare_values (vr0->min, vr0->max) == 0
2239 && compare_values (vr1->min, vr1->max) == 0
2240 && compare_values (vr0->min, vr1->min) == 0
2241 && compare_values (vr0->max, vr1->max) == 0)
2242 return boolean_false_node;
2244 /* Otherwise, they may or may not be different. */
2248 else if (comp == LT_EXPR || comp == LE_EXPR)
2252 /* If VR0 is to the left of VR1, return true. */
2253 tst = compare_values (vr0->max, vr1->min);
2254 if ((comp == LT_EXPR && tst == -1)
2255 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2256 return boolean_true_node;
2258 /* If VR0 is to the right of VR1, return false. */
2259 tst = compare_values (vr0->min, vr1->max);
2260 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2261 || (comp == LE_EXPR && tst == 1))
2262 return boolean_false_node;
2264 /* Otherwise, we don't know. */
2272 /* Given a value range VR, a value VAL and a comparison code COMP, return
2273 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2274 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2275 always returns false. Return NULL_TREE if it is not always
2276 possible to determine the value of the comparison. */
2279 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val)
2281 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2284 /* Anti-ranges need to be handled separately. */
2285 if (vr->type == VR_ANTI_RANGE)
2287 /* For anti-ranges, the only predicates that we can compute at
2288 compile time are equality and inequality. */
2295 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2296 if (value_inside_range (val, vr) == 1)
2297 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2302 if (comp == EQ_EXPR)
2304 /* EQ_EXPR may only be computed if VR represents exactly
2306 if (compare_values (vr->min, vr->max) == 0)
2308 int cmp = compare_values (vr->min, val);
2310 return boolean_true_node;
2311 else if (cmp == -1 || cmp == 1 || cmp == 2)
2312 return boolean_false_node;
2314 else if (compare_values (val, vr->min) == -1
2315 || compare_values (vr->max, val) == -1)
2316 return boolean_false_node;
2320 else if (comp == NE_EXPR)
2322 /* If VAL is not inside VR, then they are always different. */
2323 if (compare_values (vr->max, val) == -1
2324 || compare_values (vr->min, val) == 1)
2325 return boolean_true_node;
2327 /* If VR represents exactly one value equal to VAL, then return
2329 if (compare_values (vr->min, vr->max) == 0
2330 && compare_values (vr->min, val) == 0)
2331 return boolean_false_node;
2333 /* Otherwise, they may or may not be different. */
2336 else if (comp == LT_EXPR || comp == LE_EXPR)
2340 /* If VR is to the left of VAL, return true. */
2341 tst = compare_values (vr->max, val);
2342 if ((comp == LT_EXPR && tst == -1)
2343 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2344 return boolean_true_node;
2346 /* If VR is to the right of VAL, return false. */
2347 tst = compare_values (vr->min, val);
2348 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2349 || (comp == LE_EXPR && tst == 1))
2350 return boolean_false_node;
2352 /* Otherwise, we don't know. */
2355 else if (comp == GT_EXPR || comp == GE_EXPR)
2359 /* If VR is to the right of VAL, return true. */
2360 tst = compare_values (vr->min, val);
2361 if ((comp == GT_EXPR && tst == 1)
2362 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
2363 return boolean_true_node;
2365 /* If VR is to the left of VAL, return false. */
2366 tst = compare_values (vr->max, val);
2367 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
2368 || (comp == GE_EXPR && tst == -1))
2369 return boolean_false_node;
2371 /* Otherwise, we don't know. */
2379 /* Debugging dumps. */
2381 void dump_value_range (FILE *, value_range_t *);
2382 void debug_value_range (value_range_t *);
2383 void dump_all_value_ranges (FILE *);
2384 void debug_all_value_ranges (void);
2385 void dump_vr_equiv (FILE *, bitmap);
2386 void debug_vr_equiv (bitmap);
2389 /* Dump value range VR to FILE. */
2392 dump_value_range (FILE *file, value_range_t *vr)
2395 fprintf (file, "[]");
2396 else if (vr->type == VR_UNDEFINED)
2397 fprintf (file, "UNDEFINED");
2398 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
2400 tree type = TREE_TYPE (vr->min);
2402 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
2404 if (INTEGRAL_TYPE_P (type)
2405 && !TYPE_UNSIGNED (type)
2406 && vr->min == TYPE_MIN_VALUE (type))
2407 fprintf (file, "-INF");
2409 print_generic_expr (file, vr->min, 0);
2411 fprintf (file, ", ");
2413 if (INTEGRAL_TYPE_P (type)
2414 && vr->max == TYPE_MAX_VALUE (type))
2415 fprintf (file, "+INF");
2417 print_generic_expr (file, vr->max, 0);
2419 fprintf (file, "]");
2426 fprintf (file, " EQUIVALENCES: { ");
2428 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
2430 print_generic_expr (file, ssa_name (i), 0);
2431 fprintf (file, " ");
2435 fprintf (file, "} (%u elements)", c);
2438 else if (vr->type == VR_VARYING)
2439 fprintf (file, "VARYING");
2441 fprintf (file, "INVALID RANGE");
2445 /* Dump value range VR to stderr. */
2448 debug_value_range (value_range_t *vr)
2450 dump_value_range (stderr, vr);
2451 fprintf (stderr, "\n");
2455 /* Dump value ranges of all SSA_NAMEs to FILE. */
2458 dump_all_value_ranges (FILE *file)
2462 for (i = 0; i < num_ssa_names; i++)
2466 print_generic_expr (file, ssa_name (i), 0);
2467 fprintf (file, ": ");
2468 dump_value_range (file, vr_value[i]);
2469 fprintf (file, "\n");
2473 fprintf (file, "\n");
2477 /* Dump all value ranges to stderr. */
2480 debug_all_value_ranges (void)
2482 dump_all_value_ranges (stderr);
2486 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
2487 create a new SSA name N and return the assertion assignment
2488 'V = ASSERT_EXPR <V, V OP W>'. */
2491 build_assert_expr_for (tree cond, tree v)
2495 gcc_assert (TREE_CODE (v) == SSA_NAME);
2496 n = duplicate_ssa_name (v, NULL_TREE);
2498 if (COMPARISON_CLASS_P (cond))
2500 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
2501 assertion = build2 (GIMPLE_MODIFY_STMT, TREE_TYPE (v), n, a);
2503 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
2505 /* Given !V, build the assignment N = false. */
2506 tree op0 = TREE_OPERAND (cond, 0);
2507 gcc_assert (op0 == v);
2508 assertion = build2 (GIMPLE_MODIFY_STMT, TREE_TYPE (v), n,
2509 boolean_false_node);
2511 else if (TREE_CODE (cond) == SSA_NAME)
2513 /* Given V, build the assignment N = true. */
2514 gcc_assert (v == cond);
2515 assertion = build2 (GIMPLE_MODIFY_STMT,
2516 TREE_TYPE (v), n, boolean_true_node);
2521 SSA_NAME_DEF_STMT (n) = assertion;
2523 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
2524 operand of the ASSERT_EXPR. Register the new name and the old one
2525 in the replacement table so that we can fix the SSA web after
2526 adding all the ASSERT_EXPRs. */
2527 register_new_name_mapping (n, v);
2533 /* Return false if EXPR is a predicate expression involving floating
2537 fp_predicate (tree expr)
2539 return (COMPARISON_CLASS_P (expr)
2540 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
2544 /* If the range of values taken by OP can be inferred after STMT executes,
2545 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2546 describes the inferred range. Return true if a range could be
2550 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
2553 *comp_code_p = ERROR_MARK;
2555 /* Do not attempt to infer anything in names that flow through
2557 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
2560 /* Similarly, don't infer anything from statements that may throw
2562 if (tree_could_throw_p (stmt))
2565 /* If STMT is the last statement of a basic block with no
2566 successors, there is no point inferring anything about any of its
2567 operands. We would not be able to find a proper insertion point
2568 for the assertion, anyway. */
2569 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
2572 /* We can only assume that a pointer dereference will yield
2573 non-NULL if -fdelete-null-pointer-checks is enabled. */
2574 if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op)))
2577 unsigned num_uses, num_derefs;
2579 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
2582 *val_p = build_int_cst (TREE_TYPE (op), 0);
2583 *comp_code_p = NE_EXPR;
2592 void dump_asserts_for (FILE *, tree);
2593 void debug_asserts_for (tree);
2594 void dump_all_asserts (FILE *);
2595 void debug_all_asserts (void);
2597 /* Dump all the registered assertions for NAME to FILE. */
2600 dump_asserts_for (FILE *file, tree name)
2604 fprintf (file, "Assertions to be inserted for ");
2605 print_generic_expr (file, name, 0);
2606 fprintf (file, "\n");
2608 loc = asserts_for[SSA_NAME_VERSION (name)];
2611 fprintf (file, "\t");
2612 print_generic_expr (file, bsi_stmt (loc->si), 0);
2613 fprintf (file, "\n\tBB #%d", loc->bb->index);
2616 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
2617 loc->e->dest->index);
2618 dump_edge_info (file, loc->e, 0);
2620 fprintf (file, "\n\tPREDICATE: ");
2621 print_generic_expr (file, name, 0);
2622 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
2623 print_generic_expr (file, loc->val, 0);
2624 fprintf (file, "\n\n");
2628 fprintf (file, "\n");
2632 /* Dump all the registered assertions for NAME to stderr. */
2635 debug_asserts_for (tree name)
2637 dump_asserts_for (stderr, name);
2641 /* Dump all the registered assertions for all the names to FILE. */
2644 dump_all_asserts (FILE *file)
2649 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
2650 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2651 dump_asserts_for (file, ssa_name (i));
2652 fprintf (file, "\n");
2656 /* Dump all the registered assertions for all the names to stderr. */
2659 debug_all_asserts (void)
2661 dump_all_asserts (stderr);
2665 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2666 'NAME COMP_CODE VAL' at a location that dominates block BB or
2667 E->DEST, then register this location as a possible insertion point
2668 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2670 BB, E and SI provide the exact insertion point for the new
2671 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2672 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2673 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2674 must not be NULL. */
2677 register_new_assert_for (tree name,
2678 enum tree_code comp_code,
2682 block_stmt_iterator si)
2684 assert_locus_t n, loc, last_loc;
2686 basic_block dest_bb;
2688 #if defined ENABLE_CHECKING
2689 gcc_assert (bb == NULL || e == NULL);
2692 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
2693 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
2696 /* The new assertion A will be inserted at BB or E. We need to
2697 determine if the new location is dominated by a previously
2698 registered location for A. If we are doing an edge insertion,
2699 assume that A will be inserted at E->DEST. Note that this is not
2702 If E is a critical edge, it will be split. But even if E is
2703 split, the new block will dominate the same set of blocks that
2706 The reverse, however, is not true, blocks dominated by E->DEST
2707 will not be dominated by the new block created to split E. So,
2708 if the insertion location is on a critical edge, we will not use
2709 the new location to move another assertion previously registered
2710 at a block dominated by E->DEST. */
2711 dest_bb = (bb) ? bb : e->dest;
2713 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2714 VAL at a block dominating DEST_BB, then we don't need to insert a new
2715 one. Similarly, if the same assertion already exists at a block
2716 dominated by DEST_BB and the new location is not on a critical
2717 edge, then update the existing location for the assertion (i.e.,
2718 move the assertion up in the dominance tree).
2720 Note, this is implemented as a simple linked list because there
2721 should not be more than a handful of assertions registered per
2722 name. If this becomes a performance problem, a table hashed by
2723 COMP_CODE and VAL could be implemented. */
2724 loc = asserts_for[SSA_NAME_VERSION (name)];
2729 if (loc->comp_code == comp_code
2731 || operand_equal_p (loc->val, val, 0)))
2733 /* If the assertion NAME COMP_CODE VAL has already been
2734 registered at a basic block that dominates DEST_BB, then
2735 we don't need to insert the same assertion again. Note
2736 that we don't check strict dominance here to avoid
2737 replicating the same assertion inside the same basic
2738 block more than once (e.g., when a pointer is
2739 dereferenced several times inside a block).
2741 An exception to this rule are edge insertions. If the
2742 new assertion is to be inserted on edge E, then it will
2743 dominate all the other insertions that we may want to
2744 insert in DEST_BB. So, if we are doing an edge
2745 insertion, don't do this dominance check. */
2747 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
2750 /* Otherwise, if E is not a critical edge and DEST_BB
2751 dominates the existing location for the assertion, move
2752 the assertion up in the dominance tree by updating its
2753 location information. */
2754 if ((e == NULL || !EDGE_CRITICAL_P (e))
2755 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
2764 /* Update the last node of the list and move to the next one. */
2769 /* If we didn't find an assertion already registered for
2770 NAME COMP_CODE VAL, add a new one at the end of the list of
2771 assertions associated with NAME. */
2772 n = XNEW (struct assert_locus_d);
2776 n->comp_code = comp_code;
2783 asserts_for[SSA_NAME_VERSION (name)] = n;
2785 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
2788 /* COND is a predicate which uses NAME. Extract a suitable test code
2789 and value and store them into *CODE_P and *VAL_P so the predicate
2790 is normalized to NAME *CODE_P *VAL_P.
2792 If no extraction was possible, return FALSE, otherwise return TRUE.
2794 If INVERT is true, then we invert the result stored into *CODE_P. */
2797 extract_code_and_val_from_cond (tree name, tree cond, bool invert,
2798 enum tree_code *code_p, tree *val_p)
2800 enum tree_code comp_code;
2803 /* Predicates may be a single SSA name or NAME OP VAL. */
2806 /* If the predicate is a name, it must be NAME, in which
2807 case we create the predicate NAME == true or
2808 NAME == false accordingly. */
2809 comp_code = EQ_EXPR;
2810 val = invert ? boolean_false_node : boolean_true_node;
2814 /* Otherwise, we have a comparison of the form NAME COMP VAL
2815 or VAL COMP NAME. */
2816 if (name == TREE_OPERAND (cond, 1))
2818 /* If the predicate is of the form VAL COMP NAME, flip
2819 COMP around because we need to register NAME as the
2820 first operand in the predicate. */
2821 comp_code = swap_tree_comparison (TREE_CODE (cond));
2822 val = TREE_OPERAND (cond, 0);
2826 /* The comparison is of the form NAME COMP VAL, so the
2827 comparison code remains unchanged. */
2828 comp_code = TREE_CODE (cond);
2829 val = TREE_OPERAND (cond, 1);
2832 /* Invert the comparison code as necessary. */
2834 comp_code = invert_tree_comparison (comp_code, 0);
2836 /* VRP does not handle float types. */
2837 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)))
2840 /* Do not register always-false predicates.
2841 FIXME: this works around a limitation in fold() when dealing with
2842 enumerations. Given 'enum { N1, N2 } x;', fold will not
2843 fold 'if (x > N2)' to 'if (0)'. */
2844 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
2845 && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2847 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
2848 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
2850 if (comp_code == GT_EXPR
2852 || compare_values (val, max) == 0))
2855 if (comp_code == LT_EXPR
2857 || compare_values (val, min) == 0))
2861 *code_p = comp_code;
2866 /* OP is an operand of a truth value expression which is known to have
2867 a particular value. Register any asserts for OP and for any
2868 operands in OP's defining statement.
2870 If CODE is EQ_EXPR, then we want to register OP is zero (false),
2871 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
2874 register_edge_assert_for_1 (tree op, enum tree_code code,
2875 edge e, block_stmt_iterator bsi)
2877 bool retval = false;
2878 tree op_def, rhs, val;
2880 /* We only care about SSA_NAMEs. */
2881 if (TREE_CODE (op) != SSA_NAME)
2884 /* We know that OP will have a zero or nonzero value. If OP is used
2885 more than once go ahead and register an assert for OP.
2887 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
2888 it will always be set for OP (because OP is used in a COND_EXPR in
2890 if (!has_single_use (op))
2892 val = build_int_cst (TREE_TYPE (op), 0);
2893 register_new_assert_for (op, code, val, NULL, e, bsi);
2897 /* Now look at how OP is set. If it's set from a comparison,
2898 a truth operation or some bit operations, then we may be able
2899 to register information about the operands of that assignment. */
2900 op_def = SSA_NAME_DEF_STMT (op);
2901 if (TREE_CODE (op_def) != GIMPLE_MODIFY_STMT)
2904 rhs = GIMPLE_STMT_OPERAND (op_def, 1);
2906 if (COMPARISON_CLASS_P (rhs))
2908 bool invert = (code == EQ_EXPR ? true : false);
2909 tree op0 = TREE_OPERAND (rhs, 0);
2910 tree op1 = TREE_OPERAND (rhs, 1);
2912 /* Conditionally register an assert for each SSA_NAME in the
2914 if (TREE_CODE (op0) == SSA_NAME
2915 && !has_single_use (op0)
2916 && extract_code_and_val_from_cond (op0, rhs,
2917 invert, &code, &val))
2919 register_new_assert_for (op0, code, val, NULL, e, bsi);
2923 /* Similarly for the second operand of the comparison. */
2924 if (TREE_CODE (op1) == SSA_NAME
2925 && !has_single_use (op1)
2926 && extract_code_and_val_from_cond (op1, rhs,
2927 invert, &code, &val))
2929 register_new_assert_for (op1, code, val, NULL, e, bsi);
2933 else if ((code == NE_EXPR
2934 && (TREE_CODE (rhs) == TRUTH_AND_EXPR
2935 || TREE_CODE (rhs) == BIT_AND_EXPR))
2937 && (TREE_CODE (rhs) == TRUTH_OR_EXPR
2938 || TREE_CODE (rhs) == BIT_IOR_EXPR)))
2940 /* Recurse on each operand. */
2941 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
2943 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 1),
2946 else if (TREE_CODE (rhs) == TRUTH_NOT_EXPR)
2948 /* Recurse, flipping CODE. */
2949 code = invert_tree_comparison (code, false);
2950 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
2953 else if (TREE_CODE (rhs) == SSA_NAME)
2955 /* Recurse through the copy. */
2956 retval |= register_edge_assert_for_1 (rhs, code, e, bsi);
2958 else if (TREE_CODE (rhs) == NOP_EXPR
2959 || TREE_CODE (rhs) == CONVERT_EXPR
2960 || TREE_CODE (rhs) == VIEW_CONVERT_EXPR
2961 || TREE_CODE (rhs) == NON_LVALUE_EXPR)
2963 /* Recurse through the type conversion. */
2964 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
2971 /* Try to register an edge assertion for SSA name NAME on edge E for
2972 the condition COND contributing to the conditional jump pointed to by SI.
2973 Return true if an assertion for NAME could be registered. */
2976 register_edge_assert_for (tree name, edge e, block_stmt_iterator si, tree cond)
2979 enum tree_code comp_code;
2980 bool retval = false;
2981 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
2983 /* Do not attempt to infer anything in names that flow through
2985 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
2988 if (!extract_code_and_val_from_cond (name, cond, is_else_edge,
2992 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
2993 reachable from E. */
2994 if (TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
2996 register_new_assert_for (name, comp_code, val, NULL, e, si);
3000 /* If COND is effectively an equality test of an SSA_NAME against
3001 the value zero or one, then we may be able to assert values
3002 for SSA_NAMEs which flow into COND. */
3004 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
3005 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
3006 have nonzero value. */
3007 if (((comp_code == EQ_EXPR && integer_onep (val))
3008 || (comp_code == NE_EXPR && integer_zerop (val))))
3010 tree def_stmt = SSA_NAME_DEF_STMT (name);
3012 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3013 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_AND_EXPR
3014 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_AND_EXPR))
3016 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3017 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3018 retval |= register_edge_assert_for_1 (op0, NE_EXPR, e, si);
3019 retval |= register_edge_assert_for_1 (op1, NE_EXPR, e, si);
3023 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
3024 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
3026 if (((comp_code == EQ_EXPR && integer_zerop (val))
3027 || (comp_code == NE_EXPR && integer_onep (val))))
3029 tree def_stmt = SSA_NAME_DEF_STMT (name);
3031 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3032 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_OR_EXPR
3033 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_IOR_EXPR))
3035 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3036 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3037 retval |= register_edge_assert_for_1 (op0, EQ_EXPR, e, si);
3038 retval |= register_edge_assert_for_1 (op1, EQ_EXPR, e, si);
3046 static bool find_assert_locations (basic_block bb);
3048 /* Determine whether the outgoing edges of BB should receive an
3049 ASSERT_EXPR for each of the operands of BB's LAST statement.
3050 The last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
3052 If any of the sub-graphs rooted at BB have an interesting use of
3053 the predicate operands, an assert location node is added to the
3054 list of assertions for the corresponding operands. */
3057 find_conditional_asserts (basic_block bb, tree last)
3060 block_stmt_iterator bsi;
3066 need_assert = false;
3067 bsi = bsi_for_stmt (last);
3069 /* Look for uses of the operands in each of the sub-graphs
3070 rooted at BB. We need to check each of the outgoing edges
3071 separately, so that we know what kind of ASSERT_EXPR to
3073 FOR_EACH_EDGE (e, ei, bb->succs)
3078 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
3079 Otherwise, when we finish traversing each of the sub-graphs, we
3080 won't know whether the variables were found in the sub-graphs or
3081 if they had been found in a block upstream from BB.
3083 This is actually a bad idea is some cases, particularly jump
3084 threading. Consider a CFG like the following:
3094 Assume that one or more operands in the conditional at the
3095 end of block 0 are used in a conditional in block 2, but not
3096 anywhere in block 1. In this case we will not insert any
3097 assert statements in block 1, which may cause us to miss
3098 opportunities to optimize, particularly for jump threading. */
3099 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3100 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3102 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3103 to determine if any of the operands in the conditional
3104 predicate are used. */
3106 need_assert |= find_assert_locations (e->dest);
3108 /* Register the necessary assertions for each operand in the
3109 conditional predicate. */
3110 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3111 need_assert |= register_edge_assert_for (op, e, bsi,
3112 COND_EXPR_COND (last));
3115 /* Finally, indicate that we have found the operands in the
3117 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3118 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3124 /* Traverse all the statements in block BB looking for statements that
3125 may generate useful assertions for the SSA names in their operand.
3126 If a statement produces a useful assertion A for name N_i, then the
3127 list of assertions already generated for N_i is scanned to
3128 determine if A is actually needed.
3130 If N_i already had the assertion A at a location dominating the
3131 current location, then nothing needs to be done. Otherwise, the
3132 new location for A is recorded instead.
3134 1- For every statement S in BB, all the variables used by S are
3135 added to bitmap FOUND_IN_SUBGRAPH.
3137 2- If statement S uses an operand N in a way that exposes a known
3138 value range for N, then if N was not already generated by an
3139 ASSERT_EXPR, create a new assert location for N. For instance,
3140 if N is a pointer and the statement dereferences it, we can
3141 assume that N is not NULL.
3143 3- COND_EXPRs are a special case of #2. We can derive range
3144 information from the predicate but need to insert different
3145 ASSERT_EXPRs for each of the sub-graphs rooted at the
3146 conditional block. If the last statement of BB is a conditional
3147 expression of the form 'X op Y', then
3149 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
3151 b) If the conditional is the only entry point to the sub-graph
3152 corresponding to the THEN_CLAUSE, recurse into it. On
3153 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
3154 an ASSERT_EXPR is added for the corresponding variable.
3156 c) Repeat step (b) on the ELSE_CLAUSE.
3158 d) Mark X and Y in FOUND_IN_SUBGRAPH.
3167 In this case, an assertion on the THEN clause is useful to
3168 determine that 'a' is always 9 on that edge. However, an assertion
3169 on the ELSE clause would be unnecessary.
3171 4- If BB does not end in a conditional expression, then we recurse
3172 into BB's dominator children.
3174 At the end of the recursive traversal, every SSA name will have a
3175 list of locations where ASSERT_EXPRs should be added. When a new
3176 location for name N is found, it is registered by calling
3177 register_new_assert_for. That function keeps track of all the
3178 registered assertions to prevent adding unnecessary assertions.
3179 For instance, if a pointer P_4 is dereferenced more than once in a
3180 dominator tree, only the location dominating all the dereference of
3181 P_4 will receive an ASSERT_EXPR.
3183 If this function returns true, then it means that there are names
3184 for which we need to generate ASSERT_EXPRs. Those assertions are
3185 inserted by process_assert_insertions.
3187 TODO. Handle SWITCH_EXPR. */
3190 find_assert_locations (basic_block bb)
3192 block_stmt_iterator si;
3197 if (TEST_BIT (blocks_visited, bb->index))
3200 SET_BIT (blocks_visited, bb->index);
3202 need_assert = false;
3204 /* Traverse all PHI nodes in BB marking used operands. */
3205 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3207 use_operand_p arg_p;
3210 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
3212 tree arg = USE_FROM_PTR (arg_p);
3213 if (TREE_CODE (arg) == SSA_NAME)
3215 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
3216 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
3221 /* Traverse all the statements in BB marking used names and looking
3222 for statements that may infer assertions for their used operands. */
3224 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3229 stmt = bsi_stmt (si);
3231 /* See if we can derive an assertion for any of STMT's operands. */
3232 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
3235 enum tree_code comp_code;
3237 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
3238 the sub-graph of a conditional block, when we return from
3239 this recursive walk, our parent will use the
3240 FOUND_IN_SUBGRAPH bitset to determine if one of the
3241 operands it was looking for was present in the sub-graph. */
3242 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3244 /* If OP is used in such a way that we can infer a value
3245 range for it, and we don't find a previous assertion for
3246 it, create a new assertion location node for OP. */
3247 if (infer_value_range (stmt, op, &comp_code, &value))
3249 /* If we are able to infer a nonzero value range for OP,
3250 then walk backwards through the use-def chain to see if OP
3251 was set via a typecast.
3253 If so, then we can also infer a nonzero value range
3254 for the operand of the NOP_EXPR. */
3255 if (comp_code == NE_EXPR && integer_zerop (value))
3258 tree def_stmt = SSA_NAME_DEF_STMT (t);
3260 while (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3262 (GIMPLE_STMT_OPERAND (def_stmt, 1)) == NOP_EXPR
3264 (TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1),
3267 (TREE_TYPE (TREE_OPERAND
3268 (GIMPLE_STMT_OPERAND (def_stmt,
3271 t = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3272 def_stmt = SSA_NAME_DEF_STMT (t);
3274 /* Note we want to register the assert for the
3275 operand of the NOP_EXPR after SI, not after the
3277 if (! has_single_use (t))
3279 register_new_assert_for (t, comp_code, value,
3286 /* If OP is used only once, namely in this STMT, don't
3287 bother creating an ASSERT_EXPR for it. Such an
3288 ASSERT_EXPR would do nothing but increase compile time. */
3289 if (!has_single_use (op))
3291 register_new_assert_for (op, comp_code, value, bb, NULL, si);
3297 /* Remember the last statement of the block. */
3301 /* If BB's last statement is a conditional expression
3302 involving integer operands, recurse into each of the sub-graphs
3303 rooted at BB to determine if we need to add ASSERT_EXPRs. */
3305 && TREE_CODE (last) == COND_EXPR
3306 && !fp_predicate (COND_EXPR_COND (last))
3307 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
3308 need_assert |= find_conditional_asserts (bb, last);
3310 /* Recurse into the dominator children of BB. */
3311 for (son = first_dom_son (CDI_DOMINATORS, bb);
3313 son = next_dom_son (CDI_DOMINATORS, son))
3314 need_assert |= find_assert_locations (son);
3320 /* Create an ASSERT_EXPR for NAME and insert it in the location
3321 indicated by LOC. Return true if we made any edge insertions. */
3324 process_assert_insertions_for (tree name, assert_locus_t loc)
3326 /* Build the comparison expression NAME_i COMP_CODE VAL. */
3327 tree stmt, cond, assert_expr;
3331 cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
3332 assert_expr = build_assert_expr_for (cond, name);
3336 /* We have been asked to insert the assertion on an edge. This
3337 is used only by COND_EXPR and SWITCH_EXPR assertions. */
3338 #if defined ENABLE_CHECKING
3339 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
3340 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
3343 bsi_insert_on_edge (loc->e, assert_expr);
3347 /* Otherwise, we can insert right after LOC->SI iff the
3348 statement must not be the last statement in the block. */
3349 stmt = bsi_stmt (loc->si);
3350 if (!stmt_ends_bb_p (stmt))
3352 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
3356 /* If STMT must be the last statement in BB, we can only insert new
3357 assertions on the non-abnormal edge out of BB. Note that since
3358 STMT is not control flow, there may only be one non-abnormal edge
3360 FOR_EACH_EDGE (e, ei, loc->bb->succs)
3361 if (!(e->flags & EDGE_ABNORMAL))
3363 bsi_insert_on_edge (e, assert_expr);
3371 /* Process all the insertions registered for every name N_i registered
3372 in NEED_ASSERT_FOR. The list of assertions to be inserted are
3373 found in ASSERTS_FOR[i]. */
3376 process_assert_insertions (void)
3380 bool update_edges_p = false;
3381 int num_asserts = 0;
3383 if (dump_file && (dump_flags & TDF_DETAILS))
3384 dump_all_asserts (dump_file);
3386 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3388 assert_locus_t loc = asserts_for[i];
3393 assert_locus_t next = loc->next;
3394 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
3402 bsi_commit_edge_inserts ();
3404 if (dump_file && (dump_flags & TDF_STATS))
3405 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
3410 /* Traverse the flowgraph looking for conditional jumps to insert range
3411 expressions. These range expressions are meant to provide information
3412 to optimizations that need to reason in terms of value ranges. They
3413 will not be expanded into RTL. For instance, given:
3422 this pass will transform the code into:
3428 x = ASSERT_EXPR <x, x < y>
3433 y = ASSERT_EXPR <y, x <= y>
3437 The idea is that once copy and constant propagation have run, other
3438 optimizations will be able to determine what ranges of values can 'x'
3439 take in different paths of the code, simply by checking the reaching
3440 definition of 'x'. */
3443 insert_range_assertions (void)
3449 found_in_subgraph = sbitmap_alloc (num_ssa_names);
3450 sbitmap_zero (found_in_subgraph);
3452 blocks_visited = sbitmap_alloc (last_basic_block);
3453 sbitmap_zero (blocks_visited);
3455 need_assert_for = BITMAP_ALLOC (NULL);
3456 asserts_for = XCNEWVEC (assert_locus_t, num_ssa_names);
3458 calculate_dominance_info (CDI_DOMINATORS);
3460 update_ssa_p = false;
3461 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3462 if (find_assert_locations (e->dest))
3463 update_ssa_p = true;
3467 process_assert_insertions ();
3468 update_ssa (TODO_update_ssa_no_phi);
3471 if (dump_file && (dump_flags & TDF_DETAILS))
3473 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
3474 dump_function_to_file (current_function_decl, dump_file, dump_flags);
3477 sbitmap_free (found_in_subgraph);
3479 BITMAP_FREE (need_assert_for);
3482 /* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays
3483 and "struct" hacks. If VRP can determine that the
3484 array subscript is a contant, check if it is outside valid
3485 range. If the array subscript is a RANGE, warn if it is
3486 non-overlapping with valid range.
3487 IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */
3490 check_array_ref (tree ref, location_t* locus, bool ignore_off_by_one)
3492 value_range_t* vr = NULL;
3493 tree low_sub, up_sub;
3494 tree low_bound, up_bound = array_ref_up_bound (ref);
3496 low_sub = up_sub = TREE_OPERAND (ref, 1);
3498 if (!up_bound || !locus || TREE_NO_WARNING (ref)
3499 || TREE_CODE (up_bound) != INTEGER_CST
3500 /* Can not check flexible arrays. */
3501 || (TYPE_SIZE (TREE_TYPE (ref)) == NULL_TREE
3502 && TYPE_DOMAIN (TREE_TYPE (ref)) != NULL_TREE
3503 && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (ref))) == NULL_TREE)
3504 /* Accesses after the end of arrays of size 0 (gcc
3505 extension) and 1 are likely intentional ("struct
3507 || compare_tree_int (up_bound, 1) <= 0)
3510 low_bound = array_ref_low_bound (ref);
3512 if (TREE_CODE (low_sub) == SSA_NAME)
3514 vr = get_value_range (low_sub);
3515 if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
3517 low_sub = vr->type == VR_RANGE ? vr->max : vr->min;
3518 up_sub = vr->type == VR_RANGE ? vr->min : vr->max;
3522 if (vr && vr->type == VR_ANTI_RANGE)
3524 if (TREE_CODE (up_sub) == INTEGER_CST
3525 && tree_int_cst_lt (up_bound, up_sub)
3526 && TREE_CODE (low_sub) == INTEGER_CST
3527 && tree_int_cst_lt (low_sub, low_bound))
3529 warning (OPT_Warray_bounds,
3530 "%Harray subscript is outside array bounds", locus);
3531 TREE_NO_WARNING (ref) = 1;
3534 else if (TREE_CODE (up_sub) == INTEGER_CST
3535 && tree_int_cst_lt (up_bound, up_sub)
3536 && !tree_int_cst_equal (up_bound, up_sub)
3537 && (!ignore_off_by_one
3538 || !tree_int_cst_equal (int_const_binop (PLUS_EXPR,
3544 warning (OPT_Warray_bounds, "%Harray subscript is above array bounds",
3546 TREE_NO_WARNING (ref) = 1;
3548 else if (TREE_CODE (low_sub) == INTEGER_CST
3549 && tree_int_cst_lt (low_sub, low_bound))
3551 warning (OPT_Warray_bounds, "%Harray subscript is below array bounds",
3553 TREE_NO_WARNING (ref) = 1;
3557 /* walk_tree() callback that checks if *TP is
3558 an ARRAY_REF inside an ADDR_EXPR (in which an array
3559 subscript one outside the valid range is allowed). Call
3560 check_array_ref for each ARRAY_REF found. The location is
3564 check_array_bounds (tree *tp, int *walk_subtree, void *data)
3567 location_t *location = EXPR_LOCUS ((tree) data);
3569 *walk_subtree = TRUE;
3571 if (TREE_CODE (t) == ARRAY_REF)
3572 check_array_ref (t, location, false /*ignore_off_by_one*/);
3573 else if (TREE_CODE (t) == ADDR_EXPR)
3575 t = TREE_OPERAND (t, 0);
3577 /* Don't warn on statements like
3578 ssa_name = 500 + &array[-200] which are sometimes
3579 produced by various optimizing passes. */
3580 if (TREE_CODE ((tree)data) == GIMPLE_MODIFY_STMT
3581 && BINARY_CLASS_P (GIMPLE_STMT_OPERAND ((tree)data, 1)))
3583 *walk_subtree = FALSE;
3586 while (handled_component_p (t))
3588 if (TREE_CODE (t) == ARRAY_REF)
3589 check_array_ref (t, location, true /*ignore_off_by_one*/);
3590 t = TREE_OPERAND (t, 0);
3592 *walk_subtree = FALSE;
3598 /* Walk over all statements of all reachable BBs and call check_array_bounds
3602 check_all_array_refs (void)
3605 block_stmt_iterator si;
3609 /* Skip bb's that are clearly unreachable. */
3610 if (single_pred_p (bb))
3612 basic_block pred_bb = EDGE_PRED (bb, 0)->src;
3613 tree ls = NULL_TREE;
3615 if (!bsi_end_p (bsi_last (pred_bb)))
3616 ls = bsi_stmt (bsi_last (pred_bb));
3618 if (ls && TREE_CODE (ls) == COND_EXPR
3619 && ((COND_EXPR_COND (ls) == boolean_false_node
3620 && (EDGE_PRED (bb, 0)->flags & EDGE_TRUE_VALUE))
3621 || (COND_EXPR_COND (ls) == boolean_true_node
3622 && (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE))))
3625 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3626 walk_tree (bsi_stmt_ptr (si), check_array_bounds,
3627 bsi_stmt (si), NULL);
3631 /* Convert range assertion expressions into the implied copies and
3632 copy propagate away the copies. Doing the trivial copy propagation
3633 here avoids the need to run the full copy propagation pass after
3636 FIXME, this will eventually lead to copy propagation removing the
3637 names that had useful range information attached to them. For
3638 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
3639 then N_i will have the range [3, +INF].
3641 However, by converting the assertion into the implied copy
3642 operation N_i = N_j, we will then copy-propagate N_j into the uses
3643 of N_i and lose the range information. We may want to hold on to
3644 ASSERT_EXPRs a little while longer as the ranges could be used in
3645 things like jump threading.
3647 The problem with keeping ASSERT_EXPRs around is that passes after
3648 VRP need to handle them appropriately.
3650 Another approach would be to make the range information a first
3651 class property of the SSA_NAME so that it can be queried from
3652 any pass. This is made somewhat more complex by the need for
3653 multiple ranges to be associated with one SSA_NAME. */
3656 remove_range_assertions (void)
3659 block_stmt_iterator si;
3661 /* Note that the BSI iterator bump happens at the bottom of the
3662 loop and no bump is necessary if we're removing the statement
3663 referenced by the current BSI. */
3665 for (si = bsi_start (bb); !bsi_end_p (si);)
3667 tree stmt = bsi_stmt (si);
3670 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
3671 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ASSERT_EXPR)
3673 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1), var;
3674 tree cond = fold (ASSERT_EXPR_COND (rhs));
3675 use_operand_p use_p;
3676 imm_use_iterator iter;
3678 gcc_assert (cond != boolean_false_node);
3680 /* Propagate the RHS into every use of the LHS. */
3681 var = ASSERT_EXPR_VAR (rhs);
3682 FOR_EACH_IMM_USE_STMT (use_stmt, iter,
3683 GIMPLE_STMT_OPERAND (stmt, 0))
3684 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
3686 SET_USE (use_p, var);
3687 gcc_assert (TREE_CODE (var) == SSA_NAME);
3690 /* And finally, remove the copy, it is not needed. */
3691 bsi_remove (&si, true);
3692 release_defs (stmt);
3698 sbitmap_free (blocks_visited);
3702 /* Return true if STMT is interesting for VRP. */
3705 stmt_interesting_for_vrp (tree stmt)
3707 if (TREE_CODE (stmt) == PHI_NODE
3708 && is_gimple_reg (PHI_RESULT (stmt))
3709 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
3710 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
3712 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
3714 tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
3715 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
3717 /* In general, assignments with virtual operands are not useful
3718 for deriving ranges, with the obvious exception of calls to
3719 builtin functions. */
3720 if (TREE_CODE (lhs) == SSA_NAME
3721 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3722 || POINTER_TYPE_P (TREE_TYPE (lhs)))
3723 && ((TREE_CODE (rhs) == CALL_EXPR
3724 && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR
3725 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))
3726 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)))
3727 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)))
3730 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3737 /* Initialize local data structures for VRP. */
3740 vrp_initialize (void)
3744 vr_value = XCNEWVEC (value_range_t *, num_ssa_names);
3748 block_stmt_iterator si;
3751 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3753 if (!stmt_interesting_for_vrp (phi))
3755 tree lhs = PHI_RESULT (phi);
3756 set_value_range_to_varying (get_value_range (lhs));
3757 DONT_SIMULATE_AGAIN (phi) = true;
3760 DONT_SIMULATE_AGAIN (phi) = false;
3763 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3765 tree stmt = bsi_stmt (si);
3767 if (!stmt_interesting_for_vrp (stmt))
3771 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
3772 set_value_range_to_varying (get_value_range (def));
3773 DONT_SIMULATE_AGAIN (stmt) = true;
3777 DONT_SIMULATE_AGAIN (stmt) = false;
3784 /* Visit assignment STMT. If it produces an interesting range, record
3785 the SSA name in *OUTPUT_P. */
3787 static enum ssa_prop_result
3788 vrp_visit_assignment (tree stmt, tree *output_p)
3793 lhs = GIMPLE_STMT_OPERAND (stmt, 0);
3794 rhs = GIMPLE_STMT_OPERAND (stmt, 1);
3796 /* We only keep track of ranges in integral and pointer types. */
3797 if (TREE_CODE (lhs) == SSA_NAME
3798 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3799 /* It is valid to have NULL MIN/MAX values on a type. See
3800 build_range_type. */
3801 && TYPE_MIN_VALUE (TREE_TYPE (lhs))
3802 && TYPE_MAX_VALUE (TREE_TYPE (lhs)))
3803 || POINTER_TYPE_P (TREE_TYPE (lhs))))
3806 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3808 extract_range_from_expr (&new_vr, rhs);
3810 /* If STMT is inside a loop, we may be able to know something
3811 else about the range of LHS by examining scalar evolution
3813 if (current_loops && (l = loop_containing_stmt (stmt)))
3814 adjust_range_with_scev (&new_vr, l, stmt, lhs);
3816 if (update_value_range (lhs, &new_vr))
3820 if (dump_file && (dump_flags & TDF_DETAILS))
3822 fprintf (dump_file, "Found new range for ");
3823 print_generic_expr (dump_file, lhs, 0);
3824 fprintf (dump_file, ": ");
3825 dump_value_range (dump_file, &new_vr);
3826 fprintf (dump_file, "\n\n");
3829 if (new_vr.type == VR_VARYING)
3830 return SSA_PROP_VARYING;
3832 return SSA_PROP_INTERESTING;
3835 return SSA_PROP_NOT_INTERESTING;
3838 /* Every other statement produces no useful ranges. */
3839 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3840 set_value_range_to_varying (get_value_range (def));
3842 return SSA_PROP_VARYING;
3846 /* Compare all the value ranges for names equivalent to VAR with VAL
3847 using comparison code COMP. Return the same value returned by
3848 compare_range_with_value. */
3851 compare_name_with_value (enum tree_code comp, tree var, tree val)
3858 t = retval = NULL_TREE;
3860 /* Get the set of equivalences for VAR. */
3861 e = get_value_range (var)->equiv;
3863 /* Add VAR to its own set of equivalences so that VAR's value range
3864 is processed by this loop (otherwise, we would have to replicate
3865 the body of the loop just to check VAR's value range). */
3866 bitmap_set_bit (e, SSA_NAME_VERSION (var));
3868 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
3870 value_range_t equiv_vr = *(vr_value[i]);
3872 /* If name N_i does not have a valid range, use N_i as its own
3873 range. This allows us to compare against names that may
3874 have N_i in their ranges. */
3875 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
3877 equiv_vr.type = VR_RANGE;
3878 equiv_vr.min = ssa_name (i);
3879 equiv_vr.max = ssa_name (i);
3882 t = compare_range_with_value (comp, &equiv_vr, val);
3885 /* If we get different answers from different members
3886 of the equivalence set this check must be in a dead
3887 code region. Folding it to a trap representation
3888 would be correct here. For now just return don't-know. */
3899 /* Remove VAR from its own equivalence set. */
3900 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
3905 /* We couldn't find a non-NULL value for the predicate. */
3910 /* Given a comparison code COMP and names N1 and N2, compare all the
3911 ranges equivalent to N1 against all the ranges equivalent to N2
3912 to determine the value of N1 COMP N2. Return the same value
3913 returned by compare_ranges. */
3916 compare_names (enum tree_code comp, tree n1, tree n2)
3920 bitmap_iterator bi1, bi2;
3923 /* Compare the ranges of every name equivalent to N1 against the
3924 ranges of every name equivalent to N2. */
3925 e1 = get_value_range (n1)->equiv;
3926 e2 = get_value_range (n2)->equiv;
3928 /* Add N1 and N2 to their own set of equivalences to avoid
3929 duplicating the body of the loop just to check N1 and N2
3931 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
3932 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
3934 /* If the equivalence sets have a common intersection, then the two
3935 names can be compared without checking their ranges. */
3936 if (bitmap_intersect_p (e1, e2))
3938 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3939 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3941 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
3943 : boolean_false_node;
3946 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3947 N2 to their own set of equivalences to avoid duplicating the body
3948 of the loop just to check N1 and N2 ranges. */
3949 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
3951 value_range_t vr1 = *(vr_value[i1]);
3953 /* If the range is VARYING or UNDEFINED, use the name itself. */
3954 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
3956 vr1.type = VR_RANGE;
3957 vr1.min = ssa_name (i1);
3958 vr1.max = ssa_name (i1);
3961 t = retval = NULL_TREE;
3962 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
3964 value_range_t vr2 = *(vr_value[i2]);
3966 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
3968 vr2.type = VR_RANGE;
3969 vr2.min = ssa_name (i2);
3970 vr2.max = ssa_name (i2);
3973 t = compare_ranges (comp, &vr1, &vr2);
3976 /* If we get different answers from different members
3977 of the equivalence set this check must be in a dead
3978 code region. Folding it to a trap representation
3979 would be correct here. For now just return don't-know. */
3983 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3984 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3993 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3994 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3999 /* None of the equivalent ranges are useful in computing this
4001 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4002 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4007 /* Given a conditional predicate COND, try to determine if COND yields
4008 true or false based on the value ranges of its operands. Return
4009 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
4010 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
4011 NULL if the conditional cannot be evaluated at compile time.
4013 If USE_EQUIV_P is true, the ranges of all the names equivalent with
4014 the operands in COND are used when trying to compute its value.
4015 This is only used during final substitution. During propagation,
4016 we only check the range of each variable and not its equivalents. */
4019 vrp_evaluate_conditional (tree cond, bool use_equiv_p)
4021 gcc_assert (TREE_CODE (cond) == SSA_NAME
4022 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
4024 if (TREE_CODE (cond) == SSA_NAME)
4030 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node);
4033 value_range_t *vr = get_value_range (cond);
4034 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node);
4037 /* If COND has a known boolean range, return it. */
4041 /* Otherwise, if COND has a symbolic range of exactly one value,
4043 vr = get_value_range (cond);
4044 if (vr->type == VR_RANGE && vr->min == vr->max)
4049 tree op0 = TREE_OPERAND (cond, 0);
4050 tree op1 = TREE_OPERAND (cond, 1);
4052 /* We only deal with integral and pointer types. */
4053 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
4054 && !POINTER_TYPE_P (TREE_TYPE (op0)))
4059 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
4060 return compare_names (TREE_CODE (cond), op0, op1);
4061 else if (TREE_CODE (op0) == SSA_NAME)
4062 return compare_name_with_value (TREE_CODE (cond), op0, op1);
4063 else if (TREE_CODE (op1) == SSA_NAME)
4064 return compare_name_with_value (
4065 swap_tree_comparison (TREE_CODE (cond)), op1, op0);
4069 value_range_t *vr0, *vr1;
4071 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
4072 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
4075 return compare_ranges (TREE_CODE (cond), vr0, vr1);
4076 else if (vr0 && vr1 == NULL)
4077 return compare_range_with_value (TREE_CODE (cond), vr0, op1);
4078 else if (vr0 == NULL && vr1)
4079 return compare_range_with_value (
4080 swap_tree_comparison (TREE_CODE (cond)), vr1, op0);
4084 /* Anything else cannot be computed statically. */
4089 /* Visit conditional statement STMT. If we can determine which edge
4090 will be taken out of STMT's basic block, record it in
4091 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
4092 SSA_PROP_VARYING. */
4094 static enum ssa_prop_result
4095 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
4099 *taken_edge_p = NULL;
4101 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
4102 add ASSERT_EXPRs for them. */
4103 if (TREE_CODE (stmt) == SWITCH_EXPR)
4104 return SSA_PROP_VARYING;
4106 cond = COND_EXPR_COND (stmt);
4108 if (dump_file && (dump_flags & TDF_DETAILS))
4113 fprintf (dump_file, "\nVisiting conditional with predicate: ");
4114 print_generic_expr (dump_file, cond, 0);
4115 fprintf (dump_file, "\nWith known ranges\n");
4117 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
4119 fprintf (dump_file, "\t");
4120 print_generic_expr (dump_file, use, 0);
4121 fprintf (dump_file, ": ");
4122 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
4125 fprintf (dump_file, "\n");
4128 /* Compute the value of the predicate COND by checking the known
4129 ranges of each of its operands.
4131 Note that we cannot evaluate all the equivalent ranges here
4132 because those ranges may not yet be final and with the current
4133 propagation strategy, we cannot determine when the value ranges
4134 of the names in the equivalence set have changed.
4136 For instance, given the following code fragment
4140 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
4144 Assume that on the first visit to i_14, i_5 has the temporary
4145 range [8, 8] because the second argument to the PHI function is
4146 not yet executable. We derive the range ~[0, 0] for i_14 and the
4147 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
4148 the first time, since i_14 is equivalent to the range [8, 8], we
4149 determine that the predicate is always false.
4151 On the next round of propagation, i_13 is determined to be
4152 VARYING, which causes i_5 to drop down to VARYING. So, another
4153 visit to i_14 is scheduled. In this second visit, we compute the
4154 exact same range and equivalence set for i_14, namely ~[0, 0] and
4155 { i_5 }. But we did not have the previous range for i_5
4156 registered, so vrp_visit_assignment thinks that the range for
4157 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
4158 is not visited again, which stops propagation from visiting
4159 statements in the THEN clause of that if().
4161 To properly fix this we would need to keep the previous range
4162 value for the names in the equivalence set. This way we would've
4163 discovered that from one visit to the other i_5 changed from
4164 range [8, 8] to VR_VARYING.
4166 However, fixing this apparent limitation may not be worth the
4167 additional checking. Testing on several code bases (GCC, DLV,
4168 MICO, TRAMP3D and SPEC2000) showed that doing this results in
4169 4 more predicates folded in SPEC. */
4170 val = vrp_evaluate_conditional (cond, false);
4172 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
4174 if (dump_file && (dump_flags & TDF_DETAILS))
4176 fprintf (dump_file, "\nPredicate evaluates to: ");
4177 if (val == NULL_TREE)
4178 fprintf (dump_file, "DON'T KNOW\n");
4180 print_generic_stmt (dump_file, val, 0);
4183 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
4187 /* Evaluate statement STMT. If the statement produces a useful range,
4188 return SSA_PROP_INTERESTING and record the SSA name with the
4189 interesting range into *OUTPUT_P.
4191 If STMT is a conditional branch and we can determine its truth
4192 value, the taken edge is recorded in *TAKEN_EDGE_P.
4194 If STMT produces a varying value, return SSA_PROP_VARYING. */
4196 static enum ssa_prop_result
4197 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
4203 if (dump_file && (dump_flags & TDF_DETAILS))
4205 fprintf (dump_file, "\nVisiting statement:\n");
4206 print_generic_stmt (dump_file, stmt, dump_flags);
4207 fprintf (dump_file, "\n");
4210 ann = stmt_ann (stmt);
4211 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4213 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4215 /* In general, assignments with virtual operands are not useful
4216 for deriving ranges, with the obvious exception of calls to
4217 builtin functions. */
4218 if ((TREE_CODE (rhs) == CALL_EXPR
4219 && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR
4220 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))
4221 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)))
4222 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
4223 return vrp_visit_assignment (stmt, output_p);
4225 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
4226 return vrp_visit_cond_stmt (stmt, taken_edge_p);
4228 /* All other statements produce nothing of interest for VRP, so mark
4229 their outputs varying and prevent further simulation. */
4230 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
4231 set_value_range_to_varying (get_value_range (def));
4233 return SSA_PROP_VARYING;
4237 /* Meet operation for value ranges. Given two value ranges VR0 and
4238 VR1, store in VR0 a range that contains both VR0 and VR1. This
4239 may not be the smallest possible such range. */
4242 vrp_meet (value_range_t *vr0, value_range_t *vr1)
4244 if (vr0->type == VR_UNDEFINED)
4246 copy_value_range (vr0, vr1);
4250 if (vr1->type == VR_UNDEFINED)
4252 /* Nothing to do. VR0 already has the resulting range. */
4256 if (vr0->type == VR_VARYING)
4258 /* Nothing to do. VR0 already has the resulting range. */
4262 if (vr1->type == VR_VARYING)
4264 set_value_range_to_varying (vr0);
4268 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
4273 /* Compute the convex hull of the ranges. The lower limit of
4274 the new range is the minimum of the two ranges. If they
4275 cannot be compared, then give up. */
4276 cmp = compare_values (vr0->min, vr1->min);
4277 if (cmp == 0 || cmp == 1)
4284 /* Similarly, the upper limit of the new range is the maximum
4285 of the two ranges. If they cannot be compared, then
4287 cmp = compare_values (vr0->max, vr1->max);
4288 if (cmp == 0 || cmp == -1)
4295 /* The resulting set of equivalences is the intersection of
4297 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4298 bitmap_and_into (vr0->equiv, vr1->equiv);
4299 else if (vr0->equiv && !vr1->equiv)
4300 bitmap_clear (vr0->equiv);
4302 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
4304 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
4306 /* Two anti-ranges meet only if their complements intersect.
4307 Only handle the case of identical ranges. */
4308 if (compare_values (vr0->min, vr1->min) == 0
4309 && compare_values (vr0->max, vr1->max) == 0
4310 && compare_values (vr0->min, vr0->max) == 0)
4312 /* The resulting set of equivalences is the intersection of
4314 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4315 bitmap_and_into (vr0->equiv, vr1->equiv);
4316 else if (vr0->equiv && !vr1->equiv)
4317 bitmap_clear (vr0->equiv);
4322 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
4324 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
4325 only handle the case where the ranges have an empty intersection.
4326 The result of the meet operation is the anti-range. */
4327 if (!symbolic_range_p (vr0)
4328 && !symbolic_range_p (vr1)
4329 && !value_ranges_intersect_p (vr0, vr1))
4331 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
4332 set. We need to compute the intersection of the two
4333 equivalence sets. */
4334 if (vr1->type == VR_ANTI_RANGE)
4335 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
4337 /* The resulting set of equivalences is the intersection of
4339 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4340 bitmap_and_into (vr0->equiv, vr1->equiv);
4341 else if (vr0->equiv && !vr1->equiv)
4342 bitmap_clear (vr0->equiv);
4353 /* Failed to find an efficient meet. Before giving up and setting
4354 the result to VARYING, see if we can at least derive a useful
4355 anti-range. FIXME, all this nonsense about distinguishing
4356 anti-ranges from ranges is necessary because of the odd
4357 semantics of range_includes_zero_p and friends. */
4358 if (!symbolic_range_p (vr0)
4359 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
4360 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
4361 && !symbolic_range_p (vr1)
4362 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
4363 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
4365 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
4367 /* Since this meet operation did not result from the meeting of
4368 two equivalent names, VR0 cannot have any equivalences. */
4370 bitmap_clear (vr0->equiv);
4373 set_value_range_to_varying (vr0);
4377 /* Visit all arguments for PHI node PHI that flow through executable
4378 edges. If a valid value range can be derived from all the incoming
4379 value ranges, set a new range for the LHS of PHI. */
4381 static enum ssa_prop_result
4382 vrp_visit_phi_node (tree phi)
4385 tree lhs = PHI_RESULT (phi);
4386 value_range_t *lhs_vr = get_value_range (lhs);
4387 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
4388 bool all_const = true;
4390 copy_value_range (&vr_result, lhs_vr);
4392 if (dump_file && (dump_flags & TDF_DETAILS))
4394 fprintf (dump_file, "\nVisiting PHI node: ");
4395 print_generic_expr (dump_file, phi, dump_flags);
4398 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
4400 edge e = PHI_ARG_EDGE (phi, i);
4402 if (dump_file && (dump_flags & TDF_DETAILS))
4405 "\n Argument #%d (%d -> %d %sexecutable)\n",
4406 i, e->src->index, e->dest->index,
4407 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
4410 if (e->flags & EDGE_EXECUTABLE)
4412 tree arg = PHI_ARG_DEF (phi, i);
4413 value_range_t vr_arg;
4415 if (TREE_CODE (arg) == SSA_NAME)
4417 vr_arg = *(get_value_range (arg));
4422 vr_arg.type = VR_RANGE;
4425 vr_arg.equiv = NULL;
4428 if (dump_file && (dump_flags & TDF_DETAILS))
4430 fprintf (dump_file, "\t");
4431 print_generic_expr (dump_file, arg, dump_flags);
4432 fprintf (dump_file, "\n\tValue: ");
4433 dump_value_range (dump_file, &vr_arg);
4434 fprintf (dump_file, "\n");
4437 vrp_meet (&vr_result, &vr_arg);
4439 if (vr_result.type == VR_VARYING)
4444 if (vr_result.type == VR_VARYING)
4447 /* To prevent infinite iterations in the algorithm, derive ranges
4448 when the new value is slightly bigger or smaller than the
4450 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE
4453 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
4455 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
4456 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
4458 /* If the new minimum is smaller or larger than the previous
4459 one, go all the way to -INF. In the first case, to avoid
4460 iterating millions of times to reach -INF, and in the
4461 other case to avoid infinite bouncing between different
4463 if (cmp_min > 0 || cmp_min < 0)
4464 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
4466 /* Similarly, if the new maximum is smaller or larger than
4467 the previous one, go all the way to +INF. */
4468 if (cmp_max < 0 || cmp_max > 0)
4469 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
4471 /* If we ended up with a (-INF, +INF) range, set it to
4473 if (vr_result.min == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))
4474 && vr_result.max == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)))
4479 /* If the new range is different than the previous value, keep
4481 if (update_value_range (lhs, &vr_result))
4482 return SSA_PROP_INTERESTING;
4484 /* Nothing changed, don't add outgoing edges. */
4485 return SSA_PROP_NOT_INTERESTING;
4487 /* No match found. Set the LHS to VARYING. */
4489 set_value_range_to_varying (lhs_vr);
4490 return SSA_PROP_VARYING;
4493 /* Simplify a division or modulo operator to a right shift or
4494 bitwise and if the first operand is unsigned or is greater
4495 than zero and the second operand is an exact power of two. */
4498 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
4501 tree op = TREE_OPERAND (rhs, 0);
4502 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
4504 if (TYPE_UNSIGNED (TREE_TYPE (op)))
4506 val = integer_one_node;
4510 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node);
4513 if (val && integer_onep (val))
4516 tree op0 = TREE_OPERAND (rhs, 0);
4517 tree op1 = TREE_OPERAND (rhs, 1);
4519 if (rhs_code == TRUNC_DIV_EXPR)
4521 t = build_int_cst (NULL_TREE, tree_log2 (op1));
4522 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
4526 t = build_int_cst (TREE_TYPE (op1), 1);
4527 t = int_const_binop (MINUS_EXPR, op1, t, 0);
4528 t = fold_convert (TREE_TYPE (op0), t);
4529 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
4532 GIMPLE_STMT_OPERAND (stmt, 1) = t;
4537 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
4538 ABS_EXPR. If the operand is <= 0, then simplify the
4539 ABS_EXPR into a NEGATE_EXPR. */
4542 simplify_abs_using_ranges (tree stmt, tree rhs)
4545 tree op = TREE_OPERAND (rhs, 0);
4546 tree type = TREE_TYPE (op);
4547 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
4549 if (TYPE_UNSIGNED (type))
4551 val = integer_zero_node;
4555 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node);
4558 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node);
4562 if (integer_zerop (val))
4563 val = integer_one_node;
4564 else if (integer_onep (val))
4565 val = integer_zero_node;
4570 && (integer_onep (val) || integer_zerop (val)))
4574 if (integer_onep (val))
4575 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
4579 GIMPLE_STMT_OPERAND (stmt, 1) = t;
4585 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
4586 a known value range VR.
4588 If there is one and only one value which will satisfy the
4589 conditional, then return that value. Else return NULL. */
4592 test_for_singularity (enum tree_code cond_code, tree op0,
4593 tree op1, value_range_t *vr)
4598 /* Extract minimum/maximum values which satisfy the
4599 the conditional as it was written. */
4600 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
4602 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
4605 if (cond_code == LT_EXPR)
4607 tree one = build_int_cst (TREE_TYPE (op0), 1);
4608 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
4611 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
4613 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
4616 if (cond_code == GT_EXPR)
4618 tree one = build_int_cst (TREE_TYPE (op0), 1);
4619 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
4623 /* Now refine the minimum and maximum values using any
4624 value range information we have for op0. */
4627 if (compare_values (vr->min, min) == -1)
4631 if (compare_values (vr->max, max) == 1)
4636 /* If the new min/max values have converged to a single value,
4637 then there is only one value which can satisfy the condition,
4638 return that value. */
4639 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
4645 /* Simplify a conditional using a relational operator to an equality
4646 test if the range information indicates only one value can satisfy
4647 the original conditional. */
4650 simplify_cond_using_ranges (tree stmt)
4652 tree cond = COND_EXPR_COND (stmt);
4653 tree op0 = TREE_OPERAND (cond, 0);
4654 tree op1 = TREE_OPERAND (cond, 1);
4655 enum tree_code cond_code = TREE_CODE (cond);
4657 if (cond_code != NE_EXPR
4658 && cond_code != EQ_EXPR
4659 && TREE_CODE (op0) == SSA_NAME
4660 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
4661 && is_gimple_min_invariant (op1))
4663 value_range_t *vr = get_value_range (op0);
4665 /* If we have range information for OP0, then we might be
4666 able to simplify this conditional. */
4667 if (vr->type == VR_RANGE)
4669 tree new = test_for_singularity (cond_code, op0, op1, vr);
4675 fprintf (dump_file, "Simplified relational ");
4676 print_generic_expr (dump_file, cond, 0);
4677 fprintf (dump_file, " into ");
4680 COND_EXPR_COND (stmt)
4681 = build2 (EQ_EXPR, boolean_type_node, op0, new);
4686 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4687 fprintf (dump_file, "\n");
4693 /* Try again after inverting the condition. We only deal
4694 with integral types here, so no need to worry about
4695 issues with inverting FP comparisons. */
4696 cond_code = invert_tree_comparison (cond_code, false);
4697 new = test_for_singularity (cond_code, op0, op1, vr);
4703 fprintf (dump_file, "Simplified relational ");
4704 print_generic_expr (dump_file, cond, 0);
4705 fprintf (dump_file, " into ");
4708 COND_EXPR_COND (stmt)
4709 = build2 (NE_EXPR, boolean_type_node, op0, new);
4714 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4715 fprintf (dump_file, "\n");
4724 /* Simplify STMT using ranges if possible. */
4727 simplify_stmt_using_ranges (tree stmt)
4729 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4731 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4732 enum tree_code rhs_code = TREE_CODE (rhs);
4734 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
4735 and BIT_AND_EXPR respectively if the first operand is greater
4736 than zero and the second operand is an exact power of two. */
4737 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
4738 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
4739 && integer_pow2p (TREE_OPERAND (rhs, 1)))
4740 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
4742 /* Transform ABS (X) into X or -X as appropriate. */
4743 if (rhs_code == ABS_EXPR
4744 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
4745 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
4746 simplify_abs_using_ranges (stmt, rhs);
4748 else if (TREE_CODE (stmt) == COND_EXPR
4749 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
4751 simplify_cond_using_ranges (stmt);
4755 /* Stack of dest,src equivalency pairs that need to be restored after
4756 each attempt to thread a block's incoming edge to an outgoing edge.
4758 A NULL entry is used to mark the end of pairs which need to be
4760 static VEC(tree,heap) *stack;
4762 /* A trivial wrapper so that we can present the generic jump
4763 threading code with a simple API for simplifying statements. */
4765 simplify_stmt_for_jump_threading (tree stmt)
4767 /* We only use VRP information to simplify conditionals. This is
4768 overly conservative, but it's unclear if doing more would be
4769 worth the compile time cost. */
4770 if (TREE_CODE (stmt) != COND_EXPR)
4773 return vrp_evaluate_conditional (COND_EXPR_COND (stmt), true);
4776 /* Blocks which have more than one predecessor and more than
4777 one successor present jump threading opportunities. ie,
4778 when the block is reached from a specific predecessor, we
4779 may be able to determine which of the outgoing edges will
4780 be traversed. When this optimization applies, we are able
4781 to avoid conditionals at runtime and we may expose secondary
4782 optimization opportunities.
4784 This routine is effectively a driver for the generic jump
4785 threading code. It basically just presents the generic code
4786 with edges that may be suitable for jump threading.
4788 Unlike DOM, we do not iterate VRP if jump threading was successful.
4789 While iterating may expose new opportunities for VRP, it is expected
4790 those opportunities would be very limited and the compile time cost
4791 to expose those opportunities would be significant.
4793 As jump threading opportunities are discovered, they are registered
4794 for later realization. */
4797 identify_jump_threads (void)
4802 /* Ugh. When substituting values earlier in this pass we can
4803 wipe the dominance information. So rebuild the dominator
4804 information as we need it within the jump threading code. */
4805 calculate_dominance_info (CDI_DOMINATORS);
4807 /* We do not allow VRP information to be used for jump threading
4808 across a back edge in the CFG. Otherwise it becomes too
4809 difficult to avoid eliminating loop exit tests. Of course
4810 EDGE_DFS_BACK is not accurate at this time so we have to
4812 mark_dfs_back_edges ();
4814 /* Allocate our unwinder stack to unwind any temporary equivalences
4815 that might be recorded. */
4816 stack = VEC_alloc (tree, heap, 20);
4818 /* To avoid lots of silly node creation, we create a single
4819 conditional and just modify it in-place when attempting to
4821 dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL);
4822 dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL);
4824 /* Walk through all the blocks finding those which present a
4825 potential jump threading opportunity. We could set this up
4826 as a dominator walker and record data during the walk, but
4827 I doubt it's worth the effort for the classes of jump
4828 threading opportunities we are trying to identify at this
4829 point in compilation. */
4834 /* If the generic jump threading code does not find this block
4835 interesting, then there is nothing to do. */
4836 if (! potentially_threadable_block (bb))
4839 /* We only care about blocks ending in a COND_EXPR. While there
4840 may be some value in handling SWITCH_EXPR here, I doubt it's
4841 terribly important. */
4842 last = bsi_stmt (bsi_last (bb));
4843 if (TREE_CODE (last) != COND_EXPR)
4846 /* We're basically looking for any kind of conditional with
4847 integral type arguments. */
4848 cond = COND_EXPR_COND (last);
4849 if ((TREE_CODE (cond) == SSA_NAME
4850 && INTEGRAL_TYPE_P (TREE_TYPE (cond)))
4851 || (COMPARISON_CLASS_P (cond)
4852 && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
4853 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0)))
4854 && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME
4855 || is_gimple_min_invariant (TREE_OPERAND (cond, 1)))
4856 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
4861 /* We've got a block with multiple predecessors and multiple
4862 successors which also ends in a suitable conditional. For
4863 each predecessor, see if we can thread it to a specific
4865 FOR_EACH_EDGE (e, ei, bb->preds)
4867 /* Do not thread across back edges or abnormal edges
4869 if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
4872 thread_across_edge (dummy, e, true,
4874 simplify_stmt_for_jump_threading);
4879 /* We do not actually update the CFG or SSA graphs at this point as
4880 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
4881 handle ASSERT_EXPRs gracefully. */
4884 /* We identified all the jump threading opportunities earlier, but could
4885 not transform the CFG at that time. This routine transforms the
4886 CFG and arranges for the dominator tree to be rebuilt if necessary.
4888 Note the SSA graph update will occur during the normal TODO
4889 processing by the pass manager. */
4891 finalize_jump_threads (void)
4893 bool cfg_altered = false;
4894 cfg_altered = thread_through_all_blocks ();
4896 /* If we threaded jumps, then we need to recompute the dominance
4899 free_dominance_info (CDI_DOMINATORS);
4900 VEC_free (tree, heap, stack);
4904 /* Traverse all the blocks folding conditionals with known ranges. */
4910 prop_value_t *single_val_range;
4911 bool do_value_subst_p;
4915 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
4916 dump_all_value_ranges (dump_file);
4917 fprintf (dump_file, "\n");
4920 /* We may have ended with ranges that have exactly one value. Those
4921 values can be substituted as any other copy/const propagated
4922 value using substitute_and_fold. */
4923 single_val_range = XCNEWVEC (prop_value_t, num_ssa_names);
4925 do_value_subst_p = false;
4926 for (i = 0; i < num_ssa_names; i++)
4928 && vr_value[i]->type == VR_RANGE
4929 && vr_value[i]->min == vr_value[i]->max)
4931 single_val_range[i].value = vr_value[i]->min;
4932 do_value_subst_p = true;
4935 if (!do_value_subst_p)
4937 /* We found no single-valued ranges, don't waste time trying to
4938 do single value substitution in substitute_and_fold. */
4939 free (single_val_range);
4940 single_val_range = NULL;
4943 substitute_and_fold (single_val_range, true);
4945 if (warn_array_bounds)
4946 check_all_array_refs();
4948 /* We must identify jump threading opportunities before we release
4949 the datastructures built by VRP. */
4950 identify_jump_threads ();
4952 /* Free allocated memory. */
4953 for (i = 0; i < num_ssa_names; i++)
4956 BITMAP_FREE (vr_value[i]->equiv);
4960 free (single_val_range);
4963 /* So that we can distinguish between VRP data being available
4964 and not available. */
4969 /* Main entry point to VRP (Value Range Propagation). This pass is
4970 loosely based on J. R. C. Patterson, ``Accurate Static Branch
4971 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
4972 Programming Language Design and Implementation, pp. 67-78, 1995.
4973 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
4975 This is essentially an SSA-CCP pass modified to deal with ranges
4976 instead of constants.
4978 While propagating ranges, we may find that two or more SSA name
4979 have equivalent, though distinct ranges. For instance,
4982 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
4984 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
4988 In the code above, pointer p_5 has range [q_2, q_2], but from the
4989 code we can also determine that p_5 cannot be NULL and, if q_2 had
4990 a non-varying range, p_5's range should also be compatible with it.
4992 These equivalences are created by two expressions: ASSERT_EXPR and
4993 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
4994 result of another assertion, then we can use the fact that p_5 and
4995 p_4 are equivalent when evaluating p_5's range.
4997 Together with value ranges, we also propagate these equivalences
4998 between names so that we can take advantage of information from
4999 multiple ranges when doing final replacement. Note that this
5000 equivalency relation is transitive but not symmetric.
5002 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
5003 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
5004 in contexts where that assertion does not hold (e.g., in line 6).
5006 TODO, the main difference between this pass and Patterson's is that
5007 we do not propagate edge probabilities. We only compute whether
5008 edges can be taken or not. That is, instead of having a spectrum
5009 of jump probabilities between 0 and 1, we only deal with 0, 1 and
5010 DON'T KNOW. In the future, it may be worthwhile to propagate
5011 probabilities to aid branch prediction. */
5016 insert_range_assertions ();
5018 loop_optimizer_init (LOOPS_NORMAL);
5023 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
5029 loop_optimizer_finalize ();
5032 /* ASSERT_EXPRs must be removed before finalizing jump threads
5033 as finalizing jump threads calls the CFG cleanup code which
5034 does not properly handle ASSERT_EXPRs. */
5035 remove_range_assertions ();
5037 /* If we exposed any new variables, go ahead and put them into
5038 SSA form now, before we handle jump threading. This simplifies
5039 interactions between rewriting of _DECL nodes into SSA form
5040 and rewriting SSA_NAME nodes into SSA form after block
5041 duplication and CFG manipulation. */
5042 update_ssa (TODO_update_ssa);
5044 finalize_jump_threads ();
5051 return flag_tree_vrp != 0;
5054 struct tree_opt_pass pass_vrp =
5057 gate_vrp, /* gate */
5058 execute_vrp, /* execute */
5061 0, /* static_pass_number */
5062 TV_TREE_VRP, /* tv_id */
5063 PROP_ssa | PROP_alias, /* properties_required */
5064 0, /* properties_provided */
5065 0, /* properties_destroyed */
5066 0, /* todo_flags_start */
5072 | TODO_update_smt_usage, /* todo_flags_finish */