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"
36 #include "tree-scalar-evolution.h"
37 #include "tree-ssa-propagate.h"
38 #include "tree-chrec.h"
40 /* Set of SSA names found during the dominator traversal of a
41 sub-graph in find_assert_locations. */
42 static sbitmap found_in_subgraph;
44 /* Local functions. */
45 static int compare_values (tree val1, tree val2);
46 static void vrp_meet (value_range_t *, value_range_t *);
48 /* Location information for ASSERT_EXPRs. Each instance of this
49 structure describes an ASSERT_EXPR for an SSA name. Since a single
50 SSA name may have more than one assertion associated with it, these
51 locations are kept in a linked list attached to the corresponding
55 /* Basic block where the assertion would be inserted. */
58 /* Some assertions need to be inserted on an edge (e.g., assertions
59 generated by COND_EXPRs). In those cases, BB will be NULL. */
62 /* Pointer to the statement that generated this assertion. */
63 block_stmt_iterator si;
65 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
66 enum tree_code comp_code;
68 /* Value being compared against. */
71 /* Next node in the linked list. */
72 struct assert_locus_d *next;
75 typedef struct assert_locus_d *assert_locus_t;
77 /* If bit I is present, it means that SSA name N_i has a list of
78 assertions that should be inserted in the IL. */
79 static bitmap need_assert_for;
81 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
82 holds a list of ASSERT_LOCUS_T nodes that describe where
83 ASSERT_EXPRs for SSA name N_I should be inserted. */
84 static assert_locus_t *asserts_for;
86 /* Set of blocks visited in find_assert_locations. Used to avoid
87 visiting the same block more than once. */
88 static sbitmap blocks_visited;
90 /* Value range array. After propagation, VR_VALUE[I] holds the range
91 of values that SSA name N_I may take. */
92 static value_range_t **vr_value;
95 /* Return true if ARG is marked with the nonnull attribute in the
96 current function signature. */
99 nonnull_arg_p (tree arg)
101 tree t, attrs, fntype;
102 unsigned HOST_WIDE_INT arg_num;
104 gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
106 /* The static chain decl is always non null. */
107 if (arg == cfun->static_chain_decl)
110 fntype = TREE_TYPE (current_function_decl);
111 attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype));
113 /* If "nonnull" wasn't specified, we know nothing about the argument. */
114 if (attrs == NULL_TREE)
117 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
118 if (TREE_VALUE (attrs) == NULL_TREE)
121 /* Get the position number for ARG in the function signature. */
122 for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl);
124 t = TREE_CHAIN (t), arg_num++)
130 gcc_assert (t == arg);
132 /* Now see if ARG_NUM is mentioned in the nonnull list. */
133 for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
135 if (compare_tree_int (TREE_VALUE (t), arg_num) == 0)
143 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
146 set_value_range (value_range_t *vr, enum value_range_type t, tree min,
147 tree max, bitmap equiv)
149 #if defined ENABLE_CHECKING
150 /* Check the validity of the range. */
151 if (t == VR_RANGE || t == VR_ANTI_RANGE)
155 gcc_assert (min && max);
157 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
158 gcc_assert (min != TYPE_MIN_VALUE (TREE_TYPE (min))
159 || max != TYPE_MAX_VALUE (TREE_TYPE (max)));
161 cmp = compare_values (min, max);
162 gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
165 if (t == VR_UNDEFINED || t == VR_VARYING)
166 gcc_assert (min == NULL_TREE && max == NULL_TREE);
168 if (t == VR_UNDEFINED || t == VR_VARYING)
169 gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
176 /* Since updating the equivalence set involves deep copying the
177 bitmaps, only do it if absolutely necessary. */
178 if (vr->equiv == NULL)
179 vr->equiv = BITMAP_ALLOC (NULL);
181 if (equiv != vr->equiv)
183 if (equiv && !bitmap_empty_p (equiv))
184 bitmap_copy (vr->equiv, equiv);
186 bitmap_clear (vr->equiv);
191 /* Copy value range FROM into value range TO. */
194 copy_value_range (value_range_t *to, value_range_t *from)
196 set_value_range (to, from->type, from->min, from->max, from->equiv);
199 /* Set value range VR to a non-negative range of type TYPE. */
202 set_value_range_to_nonnegative (value_range_t *vr, tree type)
204 tree zero = build_int_cst (type, 0);
205 set_value_range (vr, VR_RANGE, zero, TYPE_MAX_VALUE (type), vr->equiv);
208 /* Set value range VR to a non-NULL range of type TYPE. */
211 set_value_range_to_nonnull (value_range_t *vr, tree type)
213 tree zero = build_int_cst (type, 0);
214 set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
218 /* Set value range VR to a NULL range of type TYPE. */
221 set_value_range_to_null (value_range_t *vr, tree type)
223 tree zero = build_int_cst (type, 0);
224 set_value_range (vr, VR_RANGE, zero, zero, vr->equiv);
228 /* Set value range VR to VR_VARYING. */
231 set_value_range_to_varying (value_range_t *vr)
233 vr->type = VR_VARYING;
234 vr->min = vr->max = NULL_TREE;
236 bitmap_clear (vr->equiv);
240 /* Set value range VR to a range of a truthvalue of type TYPE. */
243 set_value_range_to_truthvalue (value_range_t *vr, tree type)
245 if (TYPE_PRECISION (type) == 1)
246 set_value_range_to_varying (vr);
248 set_value_range (vr, VR_RANGE,
249 build_int_cst (type, 0), build_int_cst (type, 1),
254 /* Set value range VR to VR_UNDEFINED. */
257 set_value_range_to_undefined (value_range_t *vr)
259 vr->type = VR_UNDEFINED;
260 vr->min = vr->max = NULL_TREE;
262 bitmap_clear (vr->equiv);
266 /* Return value range information for VAR.
268 If we have no values ranges recorded (ie, VRP is not running), then
269 return NULL. Otherwise create an empty range if none existed for VAR. */
271 static value_range_t *
272 get_value_range (tree var)
276 unsigned ver = SSA_NAME_VERSION (var);
278 /* If we have no recorded ranges, then return NULL. */
286 /* Create a default value range. */
287 vr_value[ver] = vr = XCNEW (value_range_t);
289 /* Allocate an equivalence set. */
290 vr->equiv = BITMAP_ALLOC (NULL);
292 /* If VAR is a default definition, the variable can take any value
294 sym = SSA_NAME_VAR (var);
295 if (SSA_NAME_IS_DEFAULT_DEF (var))
297 /* Try to use the "nonnull" attribute to create ~[0, 0]
298 anti-ranges for pointers. Note that this is only valid with
299 default definitions of PARM_DECLs. */
300 if (TREE_CODE (sym) == PARM_DECL
301 && POINTER_TYPE_P (TREE_TYPE (sym))
302 && nonnull_arg_p (sym))
303 set_value_range_to_nonnull (vr, TREE_TYPE (sym));
305 set_value_range_to_varying (vr);
311 /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */
314 vrp_operand_equal_p (tree val1, tree val2)
318 && operand_equal_p (val1, val2, 0)));
321 /* Return true, if the bitmaps B1 and B2 are equal. */
324 vrp_bitmap_equal_p (bitmap b1, bitmap b2)
328 && bitmap_equal_p (b1, b2)));
331 /* Update the value range and equivalence set for variable VAR to
332 NEW_VR. Return true if NEW_VR is different from VAR's previous
335 NOTE: This function assumes that NEW_VR is a temporary value range
336 object created for the sole purpose of updating VAR's range. The
337 storage used by the equivalence set from NEW_VR will be freed by
338 this function. Do not call update_value_range when NEW_VR
339 is the range object associated with another SSA name. */
342 update_value_range (tree var, value_range_t *new_vr)
344 value_range_t *old_vr;
347 /* Update the value range, if necessary. */
348 old_vr = get_value_range (var);
349 is_new = old_vr->type != new_vr->type
350 || !vrp_operand_equal_p (old_vr->min, new_vr->min)
351 || !vrp_operand_equal_p (old_vr->max, new_vr->max)
352 || !vrp_bitmap_equal_p (old_vr->equiv, new_vr->equiv);
355 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
358 BITMAP_FREE (new_vr->equiv);
359 new_vr->equiv = NULL;
365 /* Add VAR and VAR's equivalence set to EQUIV. */
368 add_equivalence (bitmap equiv, tree var)
370 unsigned ver = SSA_NAME_VERSION (var);
371 value_range_t *vr = vr_value[ver];
373 bitmap_set_bit (equiv, ver);
375 bitmap_ior_into (equiv, vr->equiv);
379 /* Return true if VR is ~[0, 0]. */
382 range_is_nonnull (value_range_t *vr)
384 return vr->type == VR_ANTI_RANGE
385 && integer_zerop (vr->min)
386 && integer_zerop (vr->max);
390 /* Return true if VR is [0, 0]. */
393 range_is_null (value_range_t *vr)
395 return vr->type == VR_RANGE
396 && integer_zerop (vr->min)
397 && integer_zerop (vr->max);
401 /* Return true if value range VR involves at least one symbol. */
404 symbolic_range_p (value_range_t *vr)
406 return (!is_gimple_min_invariant (vr->min)
407 || !is_gimple_min_invariant (vr->max));
410 /* Like tree_expr_nonnegative_p, but this function uses value ranges
414 vrp_expr_computes_nonnegative (tree expr)
416 return tree_expr_nonnegative_p (expr);
419 /* Like tree_expr_nonzero_p, but this function uses value ranges
423 vrp_expr_computes_nonzero (tree expr)
425 if (tree_expr_nonzero_p (expr))
428 /* If we have an expression of the form &X->a, then the expression
429 is nonnull if X is nonnull. */
430 if (TREE_CODE (expr) == ADDR_EXPR)
432 tree base = get_base_address (TREE_OPERAND (expr, 0));
434 if (base != NULL_TREE
435 && TREE_CODE (base) == INDIRECT_REF
436 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
438 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
439 if (range_is_nonnull (vr))
447 /* Returns true if EXPR is a valid value (as expected by compare_values) --
448 a gimple invariant, or SSA_NAME +- CST. */
451 valid_value_p (tree expr)
453 if (TREE_CODE (expr) == SSA_NAME)
456 if (TREE_CODE (expr) == PLUS_EXPR
457 || TREE_CODE (expr) == MINUS_EXPR)
458 return (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME
459 && TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST);
461 return is_gimple_min_invariant (expr);
467 -2 if those are incomparable. */
469 operand_less_p (tree val, tree val2)
472 /* LT is folded faster than GE and others. Inline the common case. */
473 if (TREE_CODE (val) == INTEGER_CST && TREE_CODE (val2) == INTEGER_CST)
475 if (TYPE_UNSIGNED (TREE_TYPE (val)))
476 return INT_CST_LT_UNSIGNED (val, val2);
478 return INT_CST_LT (val, val2);
481 tcmp = fold_binary_to_constant (LT_EXPR, boolean_type_node, val, val2);
484 return !integer_zerop (tcmp);
487 /* Compare two values VAL1 and VAL2. Return
489 -2 if VAL1 and VAL2 cannot be compared at compile-time,
492 +1 if VAL1 > VAL2, and
495 This is similar to tree_int_cst_compare but supports pointer values
496 and values that cannot be compared at compile time. */
499 compare_values (tree val1, tree val2)
504 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
506 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
507 == POINTER_TYPE_P (TREE_TYPE (val2)));
509 if ((TREE_CODE (val1) == SSA_NAME
510 || TREE_CODE (val1) == PLUS_EXPR
511 || TREE_CODE (val1) == MINUS_EXPR)
512 && (TREE_CODE (val2) == SSA_NAME
513 || TREE_CODE (val2) == PLUS_EXPR
514 || TREE_CODE (val2) == MINUS_EXPR))
517 enum tree_code code1, code2;
519 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
520 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
521 same name, return -2. */
522 if (TREE_CODE (val1) == SSA_NAME)
530 code1 = TREE_CODE (val1);
531 n1 = TREE_OPERAND (val1, 0);
532 c1 = TREE_OPERAND (val1, 1);
533 if (tree_int_cst_sgn (c1) == -1)
535 c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1);
538 code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
542 if (TREE_CODE (val2) == SSA_NAME)
550 code2 = TREE_CODE (val2);
551 n2 = TREE_OPERAND (val2, 0);
552 c2 = TREE_OPERAND (val2, 1);
553 if (tree_int_cst_sgn (c2) == -1)
555 c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2);
558 code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
562 /* Both values must use the same name. */
566 if (code1 == SSA_NAME
567 && code2 == SSA_NAME)
571 /* If overflow is defined we cannot simplify more. */
572 if (TYPE_UNSIGNED (TREE_TYPE (val1))
576 if (code1 == SSA_NAME)
578 if (code2 == PLUS_EXPR)
579 /* NAME < NAME + CST */
581 else if (code2 == MINUS_EXPR)
582 /* NAME > NAME - CST */
585 else if (code1 == PLUS_EXPR)
587 if (code2 == SSA_NAME)
588 /* NAME + CST > NAME */
590 else if (code2 == PLUS_EXPR)
591 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
592 return compare_values (c1, c2);
593 else if (code2 == MINUS_EXPR)
594 /* NAME + CST1 > NAME - CST2 */
597 else if (code1 == MINUS_EXPR)
599 if (code2 == SSA_NAME)
600 /* NAME - CST < NAME */
602 else if (code2 == PLUS_EXPR)
603 /* NAME - CST1 < NAME + CST2 */
605 else if (code2 == MINUS_EXPR)
606 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
607 C1 and C2 are swapped in the call to compare_values. */
608 return compare_values (c2, c1);
614 /* We cannot compare non-constants. */
615 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
618 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
620 /* We cannot compare overflowed values. */
621 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
624 return tree_int_cst_compare (val1, val2);
630 /* First see if VAL1 and VAL2 are not the same. */
631 if (val1 == val2 || operand_equal_p (val1, val2, 0))
634 /* If VAL1 is a lower address than VAL2, return -1. */
635 if (operand_less_p (val1, val2) == 1)
638 /* If VAL1 is a higher address than VAL2, return +1. */
639 if (operand_less_p (val2, val1) == 1)
642 /* If VAL1 is different than VAL2, return +2.
643 For integer constants we either have already returned -1 or 1
644 or they are equivalent. We still might succeed in proving
645 something about non-trivial operands. */
646 if (TREE_CODE (val1) != INTEGER_CST
647 || TREE_CODE (val2) != INTEGER_CST)
649 t = fold_binary_to_constant (NE_EXPR, boolean_type_node, val1, val2);
650 if (t && tree_expr_nonzero_p (t))
659 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
660 0 if VAL is not inside VR,
661 -2 if we cannot tell either way.
663 FIXME, the current semantics of this functions are a bit quirky
664 when taken in the context of VRP. In here we do not care
665 about VR's type. If VR is the anti-range ~[3, 5] the call
666 value_inside_range (4, VR) will return 1.
668 This is counter-intuitive in a strict sense, but the callers
669 currently expect this. They are calling the function
670 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
671 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
674 This also applies to value_ranges_intersect_p and
675 range_includes_zero_p. The semantics of VR_RANGE and
676 VR_ANTI_RANGE should be encoded here, but that also means
677 adapting the users of these functions to the new semantics.
679 Benchmark compile/20001226-1.c compilation time after changing this
683 value_inside_range (tree val, value_range_t * vr)
687 cmp1 = operand_less_p (val, vr->min);
693 cmp2 = operand_less_p (vr->max, val);
701 /* Return true if value ranges VR0 and VR1 have a non-empty
704 Benchmark compile/20001226-1.c compilation time after changing this
709 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
711 /* The value ranges do not intersect if the maximum of the first range is
712 less than the minimum of the second range or vice versa.
713 When those relations are unknown, we can't do any better. */
714 if (operand_less_p (vr0->max, vr1->min) != 0)
716 if (operand_less_p (vr1->max, vr0->min) != 0)
722 /* Return true if VR includes the value zero, false otherwise. FIXME,
723 currently this will return false for an anti-range like ~[-4, 3].
724 This will be wrong when the semantics of value_inside_range are
725 modified (currently the users of this function expect these
729 range_includes_zero_p (value_range_t *vr)
733 gcc_assert (vr->type != VR_UNDEFINED
734 && vr->type != VR_VARYING
735 && !symbolic_range_p (vr));
737 zero = build_int_cst (TREE_TYPE (vr->min), 0);
738 return (value_inside_range (zero, vr) == 1);
741 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
742 false otherwise or if no value range information is available. */
745 ssa_name_nonnegative_p (tree t)
747 value_range_t *vr = get_value_range (t);
752 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
753 which would return a useful value should be encoded as a VR_RANGE. */
754 if (vr->type == VR_RANGE)
756 int result = compare_values (vr->min, integer_zero_node);
758 return (result == 0 || result == 1);
763 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
764 false otherwise or if no value range information is available. */
767 ssa_name_nonzero_p (tree t)
769 value_range_t *vr = get_value_range (t);
774 /* A VR_RANGE which does not include zero is a nonzero value. */
775 if (vr->type == VR_RANGE && !symbolic_range_p (vr))
776 return ! range_includes_zero_p (vr);
778 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
779 if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr))
780 return range_includes_zero_p (vr);
786 /* Extract value range information from an ASSERT_EXPR EXPR and store
790 extract_range_from_assert (value_range_t *vr_p, tree expr)
792 tree var, cond, limit, min, max, type;
793 value_range_t *var_vr, *limit_vr;
794 enum tree_code cond_code;
796 var = ASSERT_EXPR_VAR (expr);
797 cond = ASSERT_EXPR_COND (expr);
799 gcc_assert (COMPARISON_CLASS_P (cond));
801 /* Find VAR in the ASSERT_EXPR conditional. */
802 if (var == TREE_OPERAND (cond, 0))
804 /* If the predicate is of the form VAR COMP LIMIT, then we just
805 take LIMIT from the RHS and use the same comparison code. */
806 limit = TREE_OPERAND (cond, 1);
807 cond_code = TREE_CODE (cond);
811 /* If the predicate is of the form LIMIT COMP VAR, then we need
812 to flip around the comparison code to create the proper range
814 limit = TREE_OPERAND (cond, 0);
815 cond_code = swap_tree_comparison (TREE_CODE (cond));
818 type = TREE_TYPE (limit);
819 gcc_assert (limit != var);
821 /* For pointer arithmetic, we only keep track of pointer equality
823 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
825 set_value_range_to_varying (vr_p);
829 /* If LIMIT is another SSA name and LIMIT has a range of its own,
830 try to use LIMIT's range to avoid creating symbolic ranges
832 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
834 /* LIMIT's range is only interesting if it has any useful information. */
836 && (limit_vr->type == VR_UNDEFINED
837 || limit_vr->type == VR_VARYING
838 || symbolic_range_p (limit_vr)))
841 /* Initially, the new range has the same set of equivalences of
842 VAR's range. This will be revised before returning the final
843 value. Since assertions may be chained via mutually exclusive
844 predicates, we will need to trim the set of equivalences before
846 gcc_assert (vr_p->equiv == NULL);
847 vr_p->equiv = BITMAP_ALLOC (NULL);
848 add_equivalence (vr_p->equiv, var);
850 /* Extract a new range based on the asserted comparison for VAR and
851 LIMIT's value range. Notice that if LIMIT has an anti-range, we
852 will only use it for equality comparisons (EQ_EXPR). For any
853 other kind of assertion, we cannot derive a range from LIMIT's
854 anti-range that can be used to describe the new range. For
855 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
856 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
857 no single range for x_2 that could describe LE_EXPR, so we might
858 as well build the range [b_4, +INF] for it. */
859 if (cond_code == EQ_EXPR)
861 enum value_range_type range_type;
865 range_type = limit_vr->type;
871 range_type = VR_RANGE;
876 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
878 /* When asserting the equality VAR == LIMIT and LIMIT is another
879 SSA name, the new range will also inherit the equivalence set
881 if (TREE_CODE (limit) == SSA_NAME)
882 add_equivalence (vr_p->equiv, limit);
884 else if (cond_code == NE_EXPR)
886 /* As described above, when LIMIT's range is an anti-range and
887 this assertion is an inequality (NE_EXPR), then we cannot
888 derive anything from the anti-range. For instance, if
889 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
890 not imply that VAR's range is [0, 0]. So, in the case of
891 anti-ranges, we just assert the inequality using LIMIT and
894 If LIMIT_VR is a range, we can only use it to build a new
895 anti-range if LIMIT_VR is a single-valued range. For
896 instance, if LIMIT_VR is [0, 1], the predicate
897 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
898 Rather, it means that for value 0 VAR should be ~[0, 0]
899 and for value 1, VAR should be ~[1, 1]. We cannot
900 represent these ranges.
902 The only situation in which we can build a valid
903 anti-range is when LIMIT_VR is a single-valued range
904 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
905 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
907 && limit_vr->type == VR_RANGE
908 && compare_values (limit_vr->min, limit_vr->max) == 0)
915 /* In any other case, we cannot use LIMIT's range to build a
920 /* If MIN and MAX cover the whole range for their type, then
921 just use the original LIMIT. */
922 if (INTEGRAL_TYPE_P (type)
923 && min == TYPE_MIN_VALUE (type)
924 && max == TYPE_MAX_VALUE (type))
927 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
929 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
931 min = TYPE_MIN_VALUE (type);
933 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
937 /* If LIMIT_VR is of the form [N1, N2], we need to build the
938 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
943 /* If the maximum value forces us to be out of bounds, simply punt.
944 It would be pointless to try and do anything more since this
945 all should be optimized away above us. */
946 if (cond_code == LT_EXPR && compare_values (max, min) == 0)
947 set_value_range_to_varying (vr_p);
950 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
951 if (cond_code == LT_EXPR)
953 tree one = build_int_cst (type, 1);
954 max = fold_build2 (MINUS_EXPR, type, max, one);
957 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
960 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
962 max = TYPE_MAX_VALUE (type);
964 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
968 /* If LIMIT_VR is of the form [N1, N2], we need to build the
969 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
974 /* If the minimum value forces us to be out of bounds, simply punt.
975 It would be pointless to try and do anything more since this
976 all should be optimized away above us. */
977 if (cond_code == GT_EXPR && compare_values (min, max) == 0)
978 set_value_range_to_varying (vr_p);
981 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
982 if (cond_code == GT_EXPR)
984 tree one = build_int_cst (type, 1);
985 min = fold_build2 (PLUS_EXPR, type, min, one);
988 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
994 /* If VAR already had a known range, it may happen that the new
995 range we have computed and VAR's range are not compatible. For
999 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
1001 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
1003 While the above comes from a faulty program, it will cause an ICE
1004 later because p_8 and p_6 will have incompatible ranges and at
1005 the same time will be considered equivalent. A similar situation
1009 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
1011 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
1013 Again i_6 and i_7 will have incompatible ranges. It would be
1014 pointless to try and do anything with i_7's range because
1015 anything dominated by 'if (i_5 < 5)' will be optimized away.
1016 Note, due to the wa in which simulation proceeds, the statement
1017 i_7 = ASSERT_EXPR <...> we would never be visited because the
1018 conditional 'if (i_5 < 5)' always evaluates to false. However,
1019 this extra check does not hurt and may protect against future
1020 changes to VRP that may get into a situation similar to the
1021 NULL pointer dereference example.
1023 Note that these compatibility tests are only needed when dealing
1024 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1025 are both anti-ranges, they will always be compatible, because two
1026 anti-ranges will always have a non-empty intersection. */
1028 var_vr = get_value_range (var);
1030 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1031 ranges or anti-ranges. */
1032 if (vr_p->type == VR_VARYING
1033 || vr_p->type == VR_UNDEFINED
1034 || var_vr->type == VR_VARYING
1035 || var_vr->type == VR_UNDEFINED
1036 || symbolic_range_p (vr_p)
1037 || symbolic_range_p (var_vr))
1040 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
1042 /* If the two ranges have a non-empty intersection, we can
1043 refine the resulting range. Since the assert expression
1044 creates an equivalency and at the same time it asserts a
1045 predicate, we can take the intersection of the two ranges to
1046 get better precision. */
1047 if (value_ranges_intersect_p (var_vr, vr_p))
1049 /* Use the larger of the two minimums. */
1050 if (compare_values (vr_p->min, var_vr->min) == -1)
1055 /* Use the smaller of the two maximums. */
1056 if (compare_values (vr_p->max, var_vr->max) == 1)
1061 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
1065 /* The two ranges do not intersect, set the new range to
1066 VARYING, because we will not be able to do anything
1067 meaningful with it. */
1068 set_value_range_to_varying (vr_p);
1071 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
1072 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
1074 /* A range and an anti-range will cancel each other only if
1075 their ends are the same. For instance, in the example above,
1076 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1077 so VR_P should be set to VR_VARYING. */
1078 if (compare_values (var_vr->min, vr_p->min) == 0
1079 && compare_values (var_vr->max, vr_p->max) == 0)
1080 set_value_range_to_varying (vr_p);
1083 tree min, max, anti_min, anti_max, real_min, real_max;
1086 /* We want to compute the logical AND of the two ranges;
1087 there are three cases to consider.
1090 1. The VR_ANTI_RANGE range is completely within the
1091 VR_RANGE and the endpoints of the ranges are
1092 different. In that case the resulting range
1093 should be whichever range is more precise.
1094 Typically that will be the VR_RANGE.
1096 2. The VR_ANTI_RANGE is completely disjoint from
1097 the VR_RANGE. In this case the resulting range
1098 should be the VR_RANGE.
1100 3. There is some overlap between the VR_ANTI_RANGE
1103 3a. If the high limit of the VR_ANTI_RANGE resides
1104 within the VR_RANGE, then the result is a new
1105 VR_RANGE starting at the high limit of the
1106 the VR_ANTI_RANGE + 1 and extending to the
1107 high limit of the original VR_RANGE.
1109 3b. If the low limit of the VR_ANTI_RANGE resides
1110 within the VR_RANGE, then the result is a new
1111 VR_RANGE starting at the low limit of the original
1112 VR_RANGE and extending to the low limit of the
1113 VR_ANTI_RANGE - 1. */
1114 if (vr_p->type == VR_ANTI_RANGE)
1116 anti_min = vr_p->min;
1117 anti_max = vr_p->max;
1118 real_min = var_vr->min;
1119 real_max = var_vr->max;
1123 anti_min = var_vr->min;
1124 anti_max = var_vr->max;
1125 real_min = vr_p->min;
1126 real_max = vr_p->max;
1130 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1131 not including any endpoints. */
1132 if (compare_values (anti_max, real_max) == -1
1133 && compare_values (anti_min, real_min) == 1)
1135 set_value_range (vr_p, VR_RANGE, real_min,
1136 real_max, vr_p->equiv);
1138 /* Case 2, VR_ANTI_RANGE completely disjoint from
1140 else if (compare_values (anti_min, real_max) == 1
1141 || compare_values (anti_max, real_min) == -1)
1143 set_value_range (vr_p, VR_RANGE, real_min,
1144 real_max, vr_p->equiv);
1146 /* Case 3a, the anti-range extends into the low
1147 part of the real range. Thus creating a new
1148 low for the real range. */
1149 else if (((cmp = compare_values (anti_max, real_min)) == 1
1151 && compare_values (anti_max, real_max) == -1)
1153 min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min),
1155 build_int_cst (TREE_TYPE (var_vr->min), 1));
1157 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1159 /* Case 3b, the anti-range extends into the high
1160 part of the real range. Thus creating a new
1161 higher for the real range. */
1162 else if (compare_values (anti_min, real_min) == 1
1163 && ((cmp = compare_values (anti_min, real_max)) == -1
1166 max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min),
1168 build_int_cst (TREE_TYPE (var_vr->min), 1));
1170 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1177 /* Extract range information from SSA name VAR and store it in VR. If
1178 VAR has an interesting range, use it. Otherwise, create the
1179 range [VAR, VAR] and return it. This is useful in situations where
1180 we may have conditionals testing values of VARYING names. For
1187 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1191 extract_range_from_ssa_name (value_range_t *vr, tree var)
1193 value_range_t *var_vr = get_value_range (var);
1195 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
1196 copy_value_range (vr, var_vr);
1198 set_value_range (vr, VR_RANGE, var, var, NULL);
1200 add_equivalence (vr->equiv, var);
1204 /* Wrapper around int_const_binop. If the operation overflows and we
1205 are not using wrapping arithmetic, then adjust the result to be
1206 -INF or +INF depending on CODE, VAL1 and VAL2. */
1209 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
1213 res = int_const_binop (code, val1, val2, 0);
1215 /* If we are not using wrapping arithmetic, operate symbolically
1216 on -INF and +INF. */
1217 if (TYPE_UNSIGNED (TREE_TYPE (val1))
1220 int checkz = compare_values (res, val1);
1221 bool overflow = false;
1223 /* Ensure that res = val1 [+*] val2 >= val1
1224 or that res = val1 - val2 <= val1. */
1225 if ((code == PLUS_EXPR
1226 && !(checkz == 1 || checkz == 0))
1227 || (code == MINUS_EXPR
1228 && !(checkz == 0 || checkz == -1)))
1232 /* Checking for multiplication overflow is done by dividing the
1233 output of the multiplication by the first input of the
1234 multiplication. If the result of that division operation is
1235 not equal to the second input of the multiplication, then the
1236 multiplication overflowed. */
1237 else if (code == MULT_EXPR && !integer_zerop (val1))
1239 tree tmp = int_const_binop (TRUNC_DIV_EXPR,
1242 int check = compare_values (tmp, val2);
1250 res = copy_node (res);
1251 TREE_OVERFLOW (res) = 1;
1255 else if (TREE_OVERFLOW (res)
1256 && !TREE_OVERFLOW (val1)
1257 && !TREE_OVERFLOW (val2))
1259 /* If the operation overflowed but neither VAL1 nor VAL2 are
1260 overflown, return -INF or +INF depending on the operation
1261 and the combination of signs of the operands. */
1262 int sgn1 = tree_int_cst_sgn (val1);
1263 int sgn2 = tree_int_cst_sgn (val2);
1265 /* Notice that we only need to handle the restricted set of
1266 operations handled by extract_range_from_binary_expr.
1267 Among them, only multiplication, addition and subtraction
1268 can yield overflow without overflown operands because we
1269 are working with integral types only... except in the
1270 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1271 for division too. */
1273 /* For multiplication, the sign of the overflow is given
1274 by the comparison of the signs of the operands. */
1275 if ((code == MULT_EXPR && sgn1 == sgn2)
1276 /* For addition, the operands must be of the same sign
1277 to yield an overflow. Its sign is therefore that
1278 of one of the operands, for example the first. */
1279 || (code == PLUS_EXPR && sgn1 > 0)
1280 /* For subtraction, the operands must be of different
1281 signs to yield an overflow. Its sign is therefore
1282 that of the first operand or the opposite of that
1283 of the second operand. A first operand of 0 counts
1284 as positive here, for the corner case 0 - (-INF),
1285 which overflows, but must yield +INF. */
1286 || (code == MINUS_EXPR && sgn1 >= 0)
1287 /* For division, the only case is -INF / -1 = +INF. */
1288 || code == TRUNC_DIV_EXPR
1289 || code == FLOOR_DIV_EXPR
1290 || code == CEIL_DIV_EXPR
1291 || code == EXACT_DIV_EXPR
1292 || code == ROUND_DIV_EXPR)
1293 return TYPE_MAX_VALUE (TREE_TYPE (res));
1295 return TYPE_MIN_VALUE (TREE_TYPE (res));
1302 /* Extract range information from a binary expression EXPR based on
1303 the ranges of each of its operands and the expression code. */
1306 extract_range_from_binary_expr (value_range_t *vr, tree expr)
1308 enum tree_code code = TREE_CODE (expr);
1309 enum value_range_type type;
1310 tree op0, op1, min, max;
1312 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1313 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1315 /* Not all binary expressions can be applied to ranges in a
1316 meaningful way. Handle only arithmetic operations. */
1317 if (code != PLUS_EXPR
1318 && code != MINUS_EXPR
1319 && code != MULT_EXPR
1320 && code != TRUNC_DIV_EXPR
1321 && code != FLOOR_DIV_EXPR
1322 && code != CEIL_DIV_EXPR
1323 && code != EXACT_DIV_EXPR
1324 && code != ROUND_DIV_EXPR
1327 && code != BIT_AND_EXPR
1328 && code != TRUTH_ANDIF_EXPR
1329 && code != TRUTH_ORIF_EXPR
1330 && code != TRUTH_AND_EXPR
1331 && code != TRUTH_OR_EXPR)
1333 set_value_range_to_varying (vr);
1337 /* Get value ranges for each operand. For constant operands, create
1338 a new value range with the operand to simplify processing. */
1339 op0 = TREE_OPERAND (expr, 0);
1340 if (TREE_CODE (op0) == SSA_NAME)
1341 vr0 = *(get_value_range (op0));
1342 else if (is_gimple_min_invariant (op0))
1343 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1345 set_value_range_to_varying (&vr0);
1347 op1 = TREE_OPERAND (expr, 1);
1348 if (TREE_CODE (op1) == SSA_NAME)
1349 vr1 = *(get_value_range (op1));
1350 else if (is_gimple_min_invariant (op1))
1351 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1353 set_value_range_to_varying (&vr1);
1355 /* If either range is UNDEFINED, so is the result. */
1356 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1358 set_value_range_to_undefined (vr);
1362 /* The type of the resulting value range defaults to VR0.TYPE. */
1365 /* Refuse to operate on VARYING ranges, ranges of different kinds
1366 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1367 because we may be able to derive a useful range even if one of
1368 the operands is VR_VARYING or symbolic range. TODO, we may be
1369 able to derive anti-ranges in some cases. */
1370 if (code != BIT_AND_EXPR
1371 && code != TRUTH_AND_EXPR
1372 && code != TRUTH_OR_EXPR
1373 && (vr0.type == VR_VARYING
1374 || vr1.type == VR_VARYING
1375 || vr0.type != vr1.type
1376 || symbolic_range_p (&vr0)
1377 || symbolic_range_p (&vr1)))
1379 set_value_range_to_varying (vr);
1383 /* Now evaluate the expression to determine the new range. */
1384 if (POINTER_TYPE_P (TREE_TYPE (expr))
1385 || POINTER_TYPE_P (TREE_TYPE (op0))
1386 || POINTER_TYPE_P (TREE_TYPE (op1)))
1388 /* For pointer types, we are really only interested in asserting
1389 whether the expression evaluates to non-NULL. FIXME, we used
1390 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1391 ivopts is generating expressions with pointer multiplication
1393 if (code == PLUS_EXPR)
1395 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1396 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1397 else if (range_is_null (&vr0) && range_is_null (&vr1))
1398 set_value_range_to_null (vr, TREE_TYPE (expr));
1400 set_value_range_to_varying (vr);
1404 /* Subtracting from a pointer, may yield 0, so just drop the
1405 resulting range to varying. */
1406 set_value_range_to_varying (vr);
1412 /* For integer ranges, apply the operation to each end of the
1413 range and see what we end up with. */
1414 if (code == TRUTH_ANDIF_EXPR
1415 || code == TRUTH_ORIF_EXPR
1416 || code == TRUTH_AND_EXPR
1417 || code == TRUTH_OR_EXPR)
1419 /* If one of the operands is zero, we know that the whole
1420 expression evaluates zero. */
1421 if (code == TRUTH_AND_EXPR
1422 && ((vr0.type == VR_RANGE
1423 && integer_zerop (vr0.min)
1424 && integer_zerop (vr0.max))
1425 || (vr1.type == VR_RANGE
1426 && integer_zerop (vr1.min)
1427 && integer_zerop (vr1.max))))
1430 min = max = build_int_cst (TREE_TYPE (expr), 0);
1432 /* If one of the operands is one, we know that the whole
1433 expression evaluates one. */
1434 else if (code == TRUTH_OR_EXPR
1435 && ((vr0.type == VR_RANGE
1436 && integer_onep (vr0.min)
1437 && integer_onep (vr0.max))
1438 || (vr1.type == VR_RANGE
1439 && integer_onep (vr1.min)
1440 && integer_onep (vr1.max))))
1443 min = max = build_int_cst (TREE_TYPE (expr), 1);
1445 else if (vr0.type != VR_VARYING
1446 && vr1.type != VR_VARYING
1447 && vr0.type == vr1.type
1448 && !symbolic_range_p (&vr0)
1449 && !symbolic_range_p (&vr1))
1451 /* Boolean expressions cannot be folded with int_const_binop. */
1452 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1453 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1457 /* The result of a TRUTH_*_EXPR is always true or false. */
1458 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
1462 else if (code == PLUS_EXPR
1464 || code == MAX_EXPR)
1466 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1467 VR_VARYING. It would take more effort to compute a precise
1468 range for such a case. For example, if we have op0 == 1 and
1469 op1 == -1 with their ranges both being ~[0,0], we would have
1470 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1471 Note that we are guaranteed to have vr0.type == vr1.type at
1473 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1475 set_value_range_to_varying (vr);
1479 /* For operations that make the resulting range directly
1480 proportional to the original ranges, apply the operation to
1481 the same end of each range. */
1482 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1483 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1485 else if (code == MULT_EXPR
1486 || code == TRUNC_DIV_EXPR
1487 || code == FLOOR_DIV_EXPR
1488 || code == CEIL_DIV_EXPR
1489 || code == EXACT_DIV_EXPR
1490 || code == ROUND_DIV_EXPR)
1495 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1496 drop to VR_VARYING. It would take more effort to compute a
1497 precise range for such a case. For example, if we have
1498 op0 == 65536 and op1 == 65536 with their ranges both being
1499 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1500 we cannot claim that the product is in ~[0,0]. Note that we
1501 are guaranteed to have vr0.type == vr1.type at this
1503 if (code == MULT_EXPR
1504 && vr0.type == VR_ANTI_RANGE
1505 && (flag_wrapv || TYPE_UNSIGNED (TREE_TYPE (op0))))
1507 set_value_range_to_varying (vr);
1511 /* Multiplications and divisions are a bit tricky to handle,
1512 depending on the mix of signs we have in the two ranges, we
1513 need to operate on different values to get the minimum and
1514 maximum values for the new range. One approach is to figure
1515 out all the variations of range combinations and do the
1518 However, this involves several calls to compare_values and it
1519 is pretty convoluted. It's simpler to do the 4 operations
1520 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1521 MAX1) and then figure the smallest and largest values to form
1524 /* Divisions by zero result in a VARYING value. */
1525 if (code != MULT_EXPR
1526 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1528 set_value_range_to_varying (vr);
1532 /* Compute the 4 cross operations. */
1533 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1535 val[1] = (vr1.max != vr1.min)
1536 ? vrp_int_const_binop (code, vr0.min, vr1.max)
1539 val[2] = (vr0.max != vr0.min)
1540 ? vrp_int_const_binop (code, vr0.max, vr1.min)
1543 val[3] = (vr0.min != vr0.max && vr1.min != vr1.max)
1544 ? vrp_int_const_binop (code, vr0.max, vr1.max)
1547 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1551 for (i = 1; i < 4; i++)
1553 if (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
1554 || !is_gimple_min_invariant (max) || TREE_OVERFLOW (max))
1559 if (!is_gimple_min_invariant (val[i]) || TREE_OVERFLOW (val[i]))
1561 /* If we found an overflowed value, set MIN and MAX
1562 to it so that we set the resulting range to
1568 if (compare_values (val[i], min) == -1)
1571 if (compare_values (val[i], max) == 1)
1576 else if (code == MINUS_EXPR)
1578 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1579 VR_VARYING. It would take more effort to compute a precise
1580 range for such a case. For example, if we have op0 == 1 and
1581 op1 == 1 with their ranges both being ~[0,0], we would have
1582 op0 - op1 == 0, so we cannot claim that the difference is in
1583 ~[0,0]. Note that we are guaranteed to have
1584 vr0.type == vr1.type at this point. */
1585 if (vr0.type == VR_ANTI_RANGE)
1587 set_value_range_to_varying (vr);
1591 /* For MINUS_EXPR, apply the operation to the opposite ends of
1593 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1594 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1596 else if (code == BIT_AND_EXPR)
1598 if (vr0.type == VR_RANGE
1599 && vr0.min == vr0.max
1600 && tree_expr_nonnegative_p (vr0.max)
1601 && TREE_CODE (vr0.max) == INTEGER_CST)
1603 min = build_int_cst (TREE_TYPE (expr), 0);
1606 else if (vr1.type == VR_RANGE
1607 && vr1.min == vr1.max
1608 && tree_expr_nonnegative_p (vr1.max)
1609 && TREE_CODE (vr1.max) == INTEGER_CST)
1612 min = build_int_cst (TREE_TYPE (expr), 0);
1617 set_value_range_to_varying (vr);
1624 /* If either MIN or MAX overflowed, then set the resulting range to
1626 if (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
1627 || !is_gimple_min_invariant (max) || TREE_OVERFLOW (max))
1629 set_value_range_to_varying (vr);
1633 cmp = compare_values (min, max);
1634 if (cmp == -2 || cmp == 1)
1636 /* If the new range has its limits swapped around (MIN > MAX),
1637 then the operation caused one of them to wrap around, mark
1638 the new range VARYING. */
1639 set_value_range_to_varying (vr);
1642 set_value_range (vr, type, min, max, NULL);
1646 /* Extract range information from a unary expression EXPR based on
1647 the range of its operand and the expression code. */
1650 extract_range_from_unary_expr (value_range_t *vr, tree expr)
1652 enum tree_code code = TREE_CODE (expr);
1655 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1657 /* Refuse to operate on certain unary expressions for which we
1658 cannot easily determine a resulting range. */
1659 if (code == FIX_TRUNC_EXPR
1660 || code == FLOAT_EXPR
1661 || code == BIT_NOT_EXPR
1662 || code == NON_LVALUE_EXPR
1663 || code == CONJ_EXPR)
1665 set_value_range_to_varying (vr);
1669 /* Get value ranges for the operand. For constant operands, create
1670 a new value range with the operand to simplify processing. */
1671 op0 = TREE_OPERAND (expr, 0);
1672 if (TREE_CODE (op0) == SSA_NAME)
1673 vr0 = *(get_value_range (op0));
1674 else if (is_gimple_min_invariant (op0))
1675 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1677 set_value_range_to_varying (&vr0);
1679 /* If VR0 is UNDEFINED, so is the result. */
1680 if (vr0.type == VR_UNDEFINED)
1682 set_value_range_to_undefined (vr);
1686 /* Refuse to operate on symbolic ranges, or if neither operand is
1687 a pointer or integral type. */
1688 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0))
1689 && !POINTER_TYPE_P (TREE_TYPE (op0)))
1690 || (vr0.type != VR_VARYING
1691 && symbolic_range_p (&vr0)))
1693 set_value_range_to_varying (vr);
1697 /* If the expression involves pointers, we are only interested in
1698 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1699 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
1701 if (range_is_nonnull (&vr0) || tree_expr_nonzero_p (expr))
1702 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1703 else if (range_is_null (&vr0))
1704 set_value_range_to_null (vr, TREE_TYPE (expr));
1706 set_value_range_to_varying (vr);
1711 /* Handle unary expressions on integer ranges. */
1712 if (code == NOP_EXPR || code == CONVERT_EXPR)
1714 tree inner_type = TREE_TYPE (op0);
1715 tree outer_type = TREE_TYPE (expr);
1717 /* If VR0 represents a simple range, then try to convert
1718 the min and max values for the range to the same type
1719 as OUTER_TYPE. If the results compare equal to VR0's
1720 min and max values and the new min is still less than
1721 or equal to the new max, then we can safely use the newly
1722 computed range for EXPR. This allows us to compute
1723 accurate ranges through many casts. */
1724 if (vr0.type == VR_RANGE
1725 || (vr0.type == VR_VARYING
1726 && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type)))
1728 tree new_min, new_max, orig_min, orig_max;
1730 /* Convert the input operand min/max to OUTER_TYPE. If
1731 the input has no range information, then use the min/max
1732 for the input's type. */
1733 if (vr0.type == VR_RANGE)
1740 orig_min = TYPE_MIN_VALUE (inner_type);
1741 orig_max = TYPE_MAX_VALUE (inner_type);
1744 new_min = fold_convert (outer_type, orig_min);
1745 new_max = fold_convert (outer_type, orig_max);
1747 /* Verify the new min/max values are gimple values and
1748 that they compare equal to the original input's
1750 if (is_gimple_val (new_min)
1751 && is_gimple_val (new_max)
1752 && tree_int_cst_equal (new_min, orig_min)
1753 && tree_int_cst_equal (new_max, orig_max)
1754 && (cmp = compare_values (new_min, new_max)) <= 0
1757 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
1762 /* When converting types of different sizes, set the result to
1763 VARYING. Things like sign extensions and precision loss may
1764 change the range. For instance, if x_3 is of type 'long long
1765 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1766 is impossible to know at compile time whether y_5 will be
1768 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
1769 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
1771 set_value_range_to_varying (vr);
1776 /* Conversion of a VR_VARYING value to a wider type can result
1777 in a usable range. So wait until after we've handled conversions
1778 before dropping the result to VR_VARYING if we had a source
1779 operand that is VR_VARYING. */
1780 if (vr0.type == VR_VARYING)
1782 set_value_range_to_varying (vr);
1786 /* Apply the operation to each end of the range and see what we end
1788 if (code == NEGATE_EXPR
1789 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1791 /* NEGATE_EXPR flips the range around. We need to treat
1792 TYPE_MIN_VALUE specially dependent on wrapping, range type
1793 and if it was used as minimum or maximum value:
1794 -~[MIN, MIN] == ~[MIN, MIN]
1795 -[MIN, 0] == [0, MAX] for -fno-wrapv
1796 -[MIN, 0] == [0, MIN] for -fwrapv (will be set to varying later) */
1797 min = vr0.max == TYPE_MIN_VALUE (TREE_TYPE (expr))
1798 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1799 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1801 max = vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr))
1802 ? (vr0.type == VR_ANTI_RANGE || flag_wrapv
1803 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1804 : TYPE_MAX_VALUE (TREE_TYPE (expr)))
1805 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1808 else if (code == NEGATE_EXPR
1809 && TYPE_UNSIGNED (TREE_TYPE (expr)))
1811 if (!range_includes_zero_p (&vr0))
1813 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1814 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1818 if (range_is_null (&vr0))
1819 set_value_range_to_null (vr, TREE_TYPE (expr));
1821 set_value_range_to_varying (vr);
1825 else if (code == ABS_EXPR
1826 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1828 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1831 && ((vr0.type == VR_RANGE
1832 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1833 || (vr0.type == VR_ANTI_RANGE
1834 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
1835 && !range_includes_zero_p (&vr0))))
1837 set_value_range_to_varying (vr);
1841 /* ABS_EXPR may flip the range around, if the original range
1842 included negative values. */
1843 min = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1844 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1845 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1847 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1849 cmp = compare_values (min, max);
1851 /* If a VR_ANTI_RANGEs contains zero, then we have
1852 ~[-INF, min(MIN, MAX)]. */
1853 if (vr0.type == VR_ANTI_RANGE)
1855 if (range_includes_zero_p (&vr0))
1857 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
1859 /* Take the lower of the two values. */
1863 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1864 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1865 flag_wrapv is set and the original anti-range doesn't include
1866 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1867 min = (flag_wrapv && vr0.min != type_min_value
1868 ? int_const_binop (PLUS_EXPR,
1870 integer_one_node, 0)
1875 /* All else has failed, so create the range [0, INF], even for
1876 flag_wrapv since TYPE_MIN_VALUE is in the original
1878 vr0.type = VR_RANGE;
1879 min = build_int_cst (TREE_TYPE (expr), 0);
1880 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
1884 /* If the range contains zero then we know that the minimum value in the
1885 range will be zero. */
1886 else if (range_includes_zero_p (&vr0))
1890 min = build_int_cst (TREE_TYPE (expr), 0);
1894 /* If the range was reversed, swap MIN and MAX. */
1905 /* Otherwise, operate on each end of the range. */
1906 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1907 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1910 cmp = compare_values (min, max);
1911 if (cmp == -2 || cmp == 1)
1913 /* If the new range has its limits swapped around (MIN > MAX),
1914 then the operation caused one of them to wrap around, mark
1915 the new range VARYING. */
1916 set_value_range_to_varying (vr);
1919 set_value_range (vr, vr0.type, min, max, NULL);
1923 /* Extract range information from a conditional expression EXPR based on
1924 the ranges of each of its operands and the expression code. */
1927 extract_range_from_cond_expr (value_range_t *vr, tree expr)
1930 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1931 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1933 /* Get value ranges for each operand. For constant operands, create
1934 a new value range with the operand to simplify processing. */
1935 op0 = COND_EXPR_THEN (expr);
1936 if (TREE_CODE (op0) == SSA_NAME)
1937 vr0 = *(get_value_range (op0));
1938 else if (is_gimple_min_invariant (op0))
1939 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1941 set_value_range_to_varying (&vr0);
1943 op1 = COND_EXPR_ELSE (expr);
1944 if (TREE_CODE (op1) == SSA_NAME)
1945 vr1 = *(get_value_range (op1));
1946 else if (is_gimple_min_invariant (op1))
1947 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1949 set_value_range_to_varying (&vr1);
1951 /* The resulting value range is the union of the operand ranges */
1952 vrp_meet (&vr0, &vr1);
1953 copy_value_range (vr, &vr0);
1957 /* Extract range information from a comparison expression EXPR based
1958 on the range of its operand and the expression code. */
1961 extract_range_from_comparison (value_range_t *vr, tree expr)
1963 tree val = vrp_evaluate_conditional (expr, false);
1966 /* Since this expression was found on the RHS of an assignment,
1967 its type may be different from _Bool. Convert VAL to EXPR's
1969 val = fold_convert (TREE_TYPE (expr), val);
1970 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
1973 /* The result of a comparison is always true or false. */
1974 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
1978 /* Try to compute a useful range out of expression EXPR and store it
1982 extract_range_from_expr (value_range_t *vr, tree expr)
1984 enum tree_code code = TREE_CODE (expr);
1986 if (code == ASSERT_EXPR)
1987 extract_range_from_assert (vr, expr);
1988 else if (code == SSA_NAME)
1989 extract_range_from_ssa_name (vr, expr);
1990 else if (TREE_CODE_CLASS (code) == tcc_binary
1991 || code == TRUTH_ANDIF_EXPR
1992 || code == TRUTH_ORIF_EXPR
1993 || code == TRUTH_AND_EXPR
1994 || code == TRUTH_OR_EXPR
1995 || code == TRUTH_XOR_EXPR)
1996 extract_range_from_binary_expr (vr, expr);
1997 else if (TREE_CODE_CLASS (code) == tcc_unary)
1998 extract_range_from_unary_expr (vr, expr);
1999 else if (code == COND_EXPR)
2000 extract_range_from_cond_expr (vr, expr);
2001 else if (TREE_CODE_CLASS (code) == tcc_comparison)
2002 extract_range_from_comparison (vr, expr);
2003 else if (is_gimple_min_invariant (expr))
2004 set_value_range (vr, VR_RANGE, expr, expr, NULL);
2006 set_value_range_to_varying (vr);
2008 /* If we got a varying range from the tests above, try a final
2009 time to derive a nonnegative or nonzero range. This time
2010 relying primarily on generic routines in fold in conjunction
2012 if (vr->type == VR_VARYING)
2014 if (INTEGRAL_TYPE_P (TREE_TYPE (expr))
2015 && vrp_expr_computes_nonnegative (expr))
2016 set_value_range_to_nonnegative (vr, TREE_TYPE (expr));
2017 else if (vrp_expr_computes_nonzero (expr))
2018 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
2022 /* Given a range VR, a LOOP and a variable VAR, determine whether it
2023 would be profitable to adjust VR using scalar evolution information
2024 for VAR. If so, update VR with the new limits. */
2027 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
2030 tree init, step, chrec, tmin, tmax, min, max, type;
2031 enum ev_direction dir;
2033 /* TODO. Don't adjust anti-ranges. An anti-range may provide
2034 better opportunities than a regular range, but I'm not sure. */
2035 if (vr->type == VR_ANTI_RANGE)
2038 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
2039 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
2042 init = initial_condition_in_loop_num (chrec, loop->num);
2043 step = evolution_part_in_loop_num (chrec, loop->num);
2045 /* If STEP is symbolic, we can't know whether INIT will be the
2046 minimum or maximum value in the range. Also, unless INIT is
2047 a simple expression, compare_values and possibly other functions
2048 in tree-vrp won't be able to handle it. */
2049 if (step == NULL_TREE
2050 || !is_gimple_min_invariant (step)
2051 || !valid_value_p (init))
2054 dir = scev_direction (chrec);
2055 if (/* Do not adjust ranges if we do not know whether the iv increases
2056 or decreases, ... */
2057 dir == EV_DIR_UNKNOWN
2058 /* ... or if it may wrap. */
2059 || scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec),
2063 type = TREE_TYPE (var);
2064 if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type))
2065 tmin = lower_bound_in_type (type, type);
2067 tmin = TYPE_MIN_VALUE (type);
2068 if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type))
2069 tmax = upper_bound_in_type (type, type);
2071 tmax = TYPE_MAX_VALUE (type);
2073 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2078 /* For VARYING or UNDEFINED ranges, just about anything we get
2079 from scalar evolutions should be better. */
2081 if (dir == EV_DIR_DECREASES)
2086 /* If we would create an invalid range, then just assume we
2087 know absolutely nothing. This may be over-conservative,
2088 but it's clearly safe, and should happen only in unreachable
2089 parts of code, or for invalid programs. */
2090 if (compare_values (min, max) == 1)
2093 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2095 else if (vr->type == VR_RANGE)
2100 if (dir == EV_DIR_DECREASES)
2102 /* INIT is the maximum value. If INIT is lower than VR->MAX
2103 but no smaller than VR->MIN, set VR->MAX to INIT. */
2104 if (compare_values (init, max) == -1)
2108 /* If we just created an invalid range with the minimum
2109 greater than the maximum, we fail conservatively.
2110 This should happen only in unreachable
2111 parts of code, or for invalid programs. */
2112 if (compare_values (min, max) == 1)
2118 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2119 if (compare_values (init, min) == 1)
2123 /* Again, avoid creating invalid range by failing. */
2124 if (compare_values (min, max) == 1)
2129 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2134 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2136 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2137 all the values in the ranges.
2139 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2141 - Return NULL_TREE if it is not always possible to determine the
2142 value of the comparison. */
2146 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1)
2148 /* VARYING or UNDEFINED ranges cannot be compared. */
2149 if (vr0->type == VR_VARYING
2150 || vr0->type == VR_UNDEFINED
2151 || vr1->type == VR_VARYING
2152 || vr1->type == VR_UNDEFINED)
2155 /* Anti-ranges need to be handled separately. */
2156 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
2158 /* If both are anti-ranges, then we cannot compute any
2160 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
2163 /* These comparisons are never statically computable. */
2170 /* Equality can be computed only between a range and an
2171 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2172 if (vr0->type == VR_RANGE)
2174 /* To simplify processing, make VR0 the anti-range. */
2175 value_range_t *tmp = vr0;
2180 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
2182 if (compare_values (vr0->min, vr1->min) == 0
2183 && compare_values (vr0->max, vr1->max) == 0)
2184 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2189 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2190 operands around and change the comparison code. */
2191 if (comp == GT_EXPR || comp == GE_EXPR)
2194 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
2200 if (comp == EQ_EXPR)
2202 /* Equality may only be computed if both ranges represent
2203 exactly one value. */
2204 if (compare_values (vr0->min, vr0->max) == 0
2205 && compare_values (vr1->min, vr1->max) == 0)
2207 int cmp_min = compare_values (vr0->min, vr1->min);
2208 int cmp_max = compare_values (vr0->max, vr1->max);
2209 if (cmp_min == 0 && cmp_max == 0)
2210 return boolean_true_node;
2211 else if (cmp_min != -2 && cmp_max != -2)
2212 return boolean_false_node;
2214 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2215 else if (compare_values (vr0->min, vr1->max) == 1
2216 || compare_values (vr1->min, vr0->max) == 1)
2217 return boolean_false_node;
2221 else if (comp == NE_EXPR)
2225 /* If VR0 is completely to the left or completely to the right
2226 of VR1, they are always different. Notice that we need to
2227 make sure that both comparisons yield similar results to
2228 avoid comparing values that cannot be compared at
2230 cmp1 = compare_values (vr0->max, vr1->min);
2231 cmp2 = compare_values (vr0->min, vr1->max);
2232 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
2233 return boolean_true_node;
2235 /* If VR0 and VR1 represent a single value and are identical,
2237 else if (compare_values (vr0->min, vr0->max) == 0
2238 && compare_values (vr1->min, vr1->max) == 0
2239 && compare_values (vr0->min, vr1->min) == 0
2240 && compare_values (vr0->max, vr1->max) == 0)
2241 return boolean_false_node;
2243 /* Otherwise, they may or may not be different. */
2247 else if (comp == LT_EXPR || comp == LE_EXPR)
2251 /* If VR0 is to the left of VR1, return true. */
2252 tst = compare_values (vr0->max, vr1->min);
2253 if ((comp == LT_EXPR && tst == -1)
2254 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2255 return boolean_true_node;
2257 /* If VR0 is to the right of VR1, return false. */
2258 tst = compare_values (vr0->min, vr1->max);
2259 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2260 || (comp == LE_EXPR && tst == 1))
2261 return boolean_false_node;
2263 /* Otherwise, we don't know. */
2271 /* Given a value range VR, a value VAL and a comparison code COMP, return
2272 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2273 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2274 always returns false. Return NULL_TREE if it is not always
2275 possible to determine the value of the comparison. */
2278 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val)
2280 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2283 /* Anti-ranges need to be handled separately. */
2284 if (vr->type == VR_ANTI_RANGE)
2286 /* For anti-ranges, the only predicates that we can compute at
2287 compile time are equality and inequality. */
2294 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2295 if (value_inside_range (val, vr) == 1)
2296 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2301 if (comp == EQ_EXPR)
2303 /* EQ_EXPR may only be computed if VR represents exactly
2305 if (compare_values (vr->min, vr->max) == 0)
2307 int cmp = compare_values (vr->min, val);
2309 return boolean_true_node;
2310 else if (cmp == -1 || cmp == 1 || cmp == 2)
2311 return boolean_false_node;
2313 else if (compare_values (val, vr->min) == -1
2314 || compare_values (vr->max, val) == -1)
2315 return boolean_false_node;
2319 else if (comp == NE_EXPR)
2321 /* If VAL is not inside VR, then they are always different. */
2322 if (compare_values (vr->max, val) == -1
2323 || compare_values (vr->min, val) == 1)
2324 return boolean_true_node;
2326 /* If VR represents exactly one value equal to VAL, then return
2328 if (compare_values (vr->min, vr->max) == 0
2329 && compare_values (vr->min, val) == 0)
2330 return boolean_false_node;
2332 /* Otherwise, they may or may not be different. */
2335 else if (comp == LT_EXPR || comp == LE_EXPR)
2339 /* If VR is to the left of VAL, return true. */
2340 tst = compare_values (vr->max, val);
2341 if ((comp == LT_EXPR && tst == -1)
2342 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2343 return boolean_true_node;
2345 /* If VR is to the right of VAL, return false. */
2346 tst = compare_values (vr->min, val);
2347 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2348 || (comp == LE_EXPR && tst == 1))
2349 return boolean_false_node;
2351 /* Otherwise, we don't know. */
2354 else if (comp == GT_EXPR || comp == GE_EXPR)
2358 /* If VR is to the right of VAL, return true. */
2359 tst = compare_values (vr->min, val);
2360 if ((comp == GT_EXPR && tst == 1)
2361 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
2362 return boolean_true_node;
2364 /* If VR is to the left of VAL, return false. */
2365 tst = compare_values (vr->max, val);
2366 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
2367 || (comp == GE_EXPR && tst == -1))
2368 return boolean_false_node;
2370 /* Otherwise, we don't know. */
2378 /* Debugging dumps. */
2380 void dump_value_range (FILE *, value_range_t *);
2381 void debug_value_range (value_range_t *);
2382 void dump_all_value_ranges (FILE *);
2383 void debug_all_value_ranges (void);
2384 void dump_vr_equiv (FILE *, bitmap);
2385 void debug_vr_equiv (bitmap);
2388 /* Dump value range VR to FILE. */
2391 dump_value_range (FILE *file, value_range_t *vr)
2394 fprintf (file, "[]");
2395 else if (vr->type == VR_UNDEFINED)
2396 fprintf (file, "UNDEFINED");
2397 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
2399 tree type = TREE_TYPE (vr->min);
2401 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
2403 if (INTEGRAL_TYPE_P (type)
2404 && !TYPE_UNSIGNED (type)
2405 && vr->min == TYPE_MIN_VALUE (type))
2406 fprintf (file, "-INF");
2408 print_generic_expr (file, vr->min, 0);
2410 fprintf (file, ", ");
2412 if (INTEGRAL_TYPE_P (type)
2413 && vr->max == TYPE_MAX_VALUE (type))
2414 fprintf (file, "+INF");
2416 print_generic_expr (file, vr->max, 0);
2418 fprintf (file, "]");
2425 fprintf (file, " EQUIVALENCES: { ");
2427 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
2429 print_generic_expr (file, ssa_name (i), 0);
2430 fprintf (file, " ");
2434 fprintf (file, "} (%u elements)", c);
2437 else if (vr->type == VR_VARYING)
2438 fprintf (file, "VARYING");
2440 fprintf (file, "INVALID RANGE");
2444 /* Dump value range VR to stderr. */
2447 debug_value_range (value_range_t *vr)
2449 dump_value_range (stderr, vr);
2450 fprintf (stderr, "\n");
2454 /* Dump value ranges of all SSA_NAMEs to FILE. */
2457 dump_all_value_ranges (FILE *file)
2461 for (i = 0; i < num_ssa_names; i++)
2465 print_generic_expr (file, ssa_name (i), 0);
2466 fprintf (file, ": ");
2467 dump_value_range (file, vr_value[i]);
2468 fprintf (file, "\n");
2472 fprintf (file, "\n");
2476 /* Dump all value ranges to stderr. */
2479 debug_all_value_ranges (void)
2481 dump_all_value_ranges (stderr);
2485 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
2486 create a new SSA name N and return the assertion assignment
2487 'V = ASSERT_EXPR <V, V OP W>'. */
2490 build_assert_expr_for (tree cond, tree v)
2494 gcc_assert (TREE_CODE (v) == SSA_NAME);
2495 n = duplicate_ssa_name (v, NULL_TREE);
2497 if (COMPARISON_CLASS_P (cond))
2499 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
2500 assertion = build2 (GIMPLE_MODIFY_STMT, TREE_TYPE (v), n, a);
2502 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
2504 /* Given !V, build the assignment N = false. */
2505 tree op0 = TREE_OPERAND (cond, 0);
2506 gcc_assert (op0 == v);
2507 assertion = build2 (GIMPLE_MODIFY_STMT, TREE_TYPE (v), n,
2508 boolean_false_node);
2510 else if (TREE_CODE (cond) == SSA_NAME)
2512 /* Given V, build the assignment N = true. */
2513 gcc_assert (v == cond);
2514 assertion = build2 (GIMPLE_MODIFY_STMT,
2515 TREE_TYPE (v), n, boolean_true_node);
2520 SSA_NAME_DEF_STMT (n) = assertion;
2522 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
2523 operand of the ASSERT_EXPR. Register the new name and the old one
2524 in the replacement table so that we can fix the SSA web after
2525 adding all the ASSERT_EXPRs. */
2526 register_new_name_mapping (n, v);
2532 /* Return false if EXPR is a predicate expression involving floating
2536 fp_predicate (tree expr)
2538 return (COMPARISON_CLASS_P (expr)
2539 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
2543 /* If the range of values taken by OP can be inferred after STMT executes,
2544 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2545 describes the inferred range. Return true if a range could be
2549 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
2552 *comp_code_p = ERROR_MARK;
2554 /* Do not attempt to infer anything in names that flow through
2556 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
2559 /* Similarly, don't infer anything from statements that may throw
2561 if (tree_could_throw_p (stmt))
2564 /* If STMT is the last statement of a basic block with no
2565 successors, there is no point inferring anything about any of its
2566 operands. We would not be able to find a proper insertion point
2567 for the assertion, anyway. */
2568 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
2571 /* We can only assume that a pointer dereference will yield
2572 non-NULL if -fdelete-null-pointer-checks is enabled. */
2573 if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op)))
2576 unsigned num_uses, num_derefs;
2578 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
2581 *val_p = build_int_cst (TREE_TYPE (op), 0);
2582 *comp_code_p = NE_EXPR;
2591 void dump_asserts_for (FILE *, tree);
2592 void debug_asserts_for (tree);
2593 void dump_all_asserts (FILE *);
2594 void debug_all_asserts (void);
2596 /* Dump all the registered assertions for NAME to FILE. */
2599 dump_asserts_for (FILE *file, tree name)
2603 fprintf (file, "Assertions to be inserted for ");
2604 print_generic_expr (file, name, 0);
2605 fprintf (file, "\n");
2607 loc = asserts_for[SSA_NAME_VERSION (name)];
2610 fprintf (file, "\t");
2611 print_generic_expr (file, bsi_stmt (loc->si), 0);
2612 fprintf (file, "\n\tBB #%d", loc->bb->index);
2615 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
2616 loc->e->dest->index);
2617 dump_edge_info (file, loc->e, 0);
2619 fprintf (file, "\n\tPREDICATE: ");
2620 print_generic_expr (file, name, 0);
2621 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
2622 print_generic_expr (file, loc->val, 0);
2623 fprintf (file, "\n\n");
2627 fprintf (file, "\n");
2631 /* Dump all the registered assertions for NAME to stderr. */
2634 debug_asserts_for (tree name)
2636 dump_asserts_for (stderr, name);
2640 /* Dump all the registered assertions for all the names to FILE. */
2643 dump_all_asserts (FILE *file)
2648 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
2649 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2650 dump_asserts_for (file, ssa_name (i));
2651 fprintf (file, "\n");
2655 /* Dump all the registered assertions for all the names to stderr. */
2658 debug_all_asserts (void)
2660 dump_all_asserts (stderr);
2664 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2665 'NAME COMP_CODE VAL' at a location that dominates block BB or
2666 E->DEST, then register this location as a possible insertion point
2667 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2669 BB, E and SI provide the exact insertion point for the new
2670 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2671 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2672 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2673 must not be NULL. */
2676 register_new_assert_for (tree name,
2677 enum tree_code comp_code,
2681 block_stmt_iterator si)
2683 assert_locus_t n, loc, last_loc;
2685 basic_block dest_bb;
2687 #if defined ENABLE_CHECKING
2688 gcc_assert (bb == NULL || e == NULL);
2691 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
2692 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
2695 /* The new assertion A will be inserted at BB or E. We need to
2696 determine if the new location is dominated by a previously
2697 registered location for A. If we are doing an edge insertion,
2698 assume that A will be inserted at E->DEST. Note that this is not
2701 If E is a critical edge, it will be split. But even if E is
2702 split, the new block will dominate the same set of blocks that
2705 The reverse, however, is not true, blocks dominated by E->DEST
2706 will not be dominated by the new block created to split E. So,
2707 if the insertion location is on a critical edge, we will not use
2708 the new location to move another assertion previously registered
2709 at a block dominated by E->DEST. */
2710 dest_bb = (bb) ? bb : e->dest;
2712 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2713 VAL at a block dominating DEST_BB, then we don't need to insert a new
2714 one. Similarly, if the same assertion already exists at a block
2715 dominated by DEST_BB and the new location is not on a critical
2716 edge, then update the existing location for the assertion (i.e.,
2717 move the assertion up in the dominance tree).
2719 Note, this is implemented as a simple linked list because there
2720 should not be more than a handful of assertions registered per
2721 name. If this becomes a performance problem, a table hashed by
2722 COMP_CODE and VAL could be implemented. */
2723 loc = asserts_for[SSA_NAME_VERSION (name)];
2728 if (loc->comp_code == comp_code
2730 || operand_equal_p (loc->val, val, 0)))
2732 /* If the assertion NAME COMP_CODE VAL has already been
2733 registered at a basic block that dominates DEST_BB, then
2734 we don't need to insert the same assertion again. Note
2735 that we don't check strict dominance here to avoid
2736 replicating the same assertion inside the same basic
2737 block more than once (e.g., when a pointer is
2738 dereferenced several times inside a block).
2740 An exception to this rule are edge insertions. If the
2741 new assertion is to be inserted on edge E, then it will
2742 dominate all the other insertions that we may want to
2743 insert in DEST_BB. So, if we are doing an edge
2744 insertion, don't do this dominance check. */
2746 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
2749 /* Otherwise, if E is not a critical edge and DEST_BB
2750 dominates the existing location for the assertion, move
2751 the assertion up in the dominance tree by updating its
2752 location information. */
2753 if ((e == NULL || !EDGE_CRITICAL_P (e))
2754 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
2763 /* Update the last node of the list and move to the next one. */
2768 /* If we didn't find an assertion already registered for
2769 NAME COMP_CODE VAL, add a new one at the end of the list of
2770 assertions associated with NAME. */
2771 n = XNEW (struct assert_locus_d);
2775 n->comp_code = comp_code;
2782 asserts_for[SSA_NAME_VERSION (name)] = n;
2784 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
2787 /* COND is a predicate which uses NAME. Extract a suitable test code
2788 and value and store them into *CODE_P and *VAL_P so the predicate
2789 is normalized to NAME *CODE_P *VAL_P.
2791 If no extraction was possible, return FALSE, otherwise return TRUE.
2793 If INVERT is true, then we invert the result stored into *CODE_P. */
2796 extract_code_and_val_from_cond (tree name, tree cond, bool invert,
2797 enum tree_code *code_p, tree *val_p)
2799 enum tree_code comp_code;
2802 /* Predicates may be a single SSA name or NAME OP VAL. */
2805 /* If the predicate is a name, it must be NAME, in which
2806 case we create the predicate NAME == true or
2807 NAME == false accordingly. */
2808 comp_code = EQ_EXPR;
2809 val = invert ? boolean_false_node : boolean_true_node;
2813 /* Otherwise, we have a comparison of the form NAME COMP VAL
2814 or VAL COMP NAME. */
2815 if (name == TREE_OPERAND (cond, 1))
2817 /* If the predicate is of the form VAL COMP NAME, flip
2818 COMP around because we need to register NAME as the
2819 first operand in the predicate. */
2820 comp_code = swap_tree_comparison (TREE_CODE (cond));
2821 val = TREE_OPERAND (cond, 0);
2825 /* The comparison is of the form NAME COMP VAL, so the
2826 comparison code remains unchanged. */
2827 comp_code = TREE_CODE (cond);
2828 val = TREE_OPERAND (cond, 1);
2831 /* Invert the comparison code as necessary. */
2833 comp_code = invert_tree_comparison (comp_code, 0);
2835 /* VRP does not handle float types. */
2836 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)))
2839 /* Do not register always-false predicates.
2840 FIXME: this works around a limitation in fold() when dealing with
2841 enumerations. Given 'enum { N1, N2 } x;', fold will not
2842 fold 'if (x > N2)' to 'if (0)'. */
2843 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
2844 && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2846 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
2847 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
2849 if (comp_code == GT_EXPR
2851 || compare_values (val, max) == 0))
2854 if (comp_code == LT_EXPR
2856 || compare_values (val, min) == 0))
2860 *code_p = comp_code;
2865 /* OP is an operand of a truth value expression which is known to have
2866 a particular value. Register any asserts for OP and for any
2867 operands in OP's defining statement.
2869 If CODE is EQ_EXPR, then we want to register OP is zero (false),
2870 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
2873 register_edge_assert_for_1 (tree op, enum tree_code code,
2874 edge e, block_stmt_iterator bsi)
2876 bool retval = false;
2877 tree op_def, rhs, val;
2879 /* We only care about SSA_NAMEs. */
2880 if (TREE_CODE (op) != SSA_NAME)
2883 /* We know that OP will have a zero or nonzero value. If OP is used
2884 more than once go ahead and register an assert for OP.
2886 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
2887 it will always be set for OP (because OP is used in a COND_EXPR in
2889 if (!has_single_use (op))
2891 val = build_int_cst (TREE_TYPE (op), 0);
2892 register_new_assert_for (op, code, val, NULL, e, bsi);
2896 /* Now look at how OP is set. If it's set from a comparison,
2897 a truth operation or some bit operations, then we may be able
2898 to register information about the operands of that assignment. */
2899 op_def = SSA_NAME_DEF_STMT (op);
2900 if (TREE_CODE (op_def) != GIMPLE_MODIFY_STMT)
2903 rhs = GIMPLE_STMT_OPERAND (op_def, 1);
2905 if (COMPARISON_CLASS_P (rhs))
2907 bool invert = (code == EQ_EXPR ? true : false);
2908 tree op0 = TREE_OPERAND (rhs, 0);
2909 tree op1 = TREE_OPERAND (rhs, 1);
2911 /* Conditionally register an assert for each SSA_NAME in the
2913 if (TREE_CODE (op0) == SSA_NAME
2914 && !has_single_use (op0)
2915 && extract_code_and_val_from_cond (op0, rhs,
2916 invert, &code, &val))
2918 register_new_assert_for (op0, code, val, NULL, e, bsi);
2922 /* Similarly for the second operand of the comparison. */
2923 if (TREE_CODE (op1) == SSA_NAME
2924 && !has_single_use (op1)
2925 && extract_code_and_val_from_cond (op1, rhs,
2926 invert, &code, &val))
2928 register_new_assert_for (op1, code, val, NULL, e, bsi);
2932 else if ((code == NE_EXPR
2933 && (TREE_CODE (rhs) == TRUTH_AND_EXPR
2934 || TREE_CODE (rhs) == BIT_AND_EXPR))
2936 && (TREE_CODE (rhs) == TRUTH_OR_EXPR
2937 || TREE_CODE (rhs) == BIT_IOR_EXPR)))
2939 /* Recurse on each operand. */
2940 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
2942 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 1),
2945 else if (TREE_CODE (rhs) == TRUTH_NOT_EXPR)
2947 /* Recurse, flipping CODE. */
2948 code = invert_tree_comparison (code, false);
2949 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
2952 else if (TREE_CODE (rhs) == SSA_NAME)
2954 /* Recurse through the copy. */
2955 retval |= register_edge_assert_for_1 (rhs, code, e, bsi);
2957 else if (TREE_CODE (rhs) == NOP_EXPR
2958 || TREE_CODE (rhs) == CONVERT_EXPR
2959 || TREE_CODE (rhs) == VIEW_CONVERT_EXPR
2960 || TREE_CODE (rhs) == NON_LVALUE_EXPR)
2962 /* Recurse through the type conversion. */
2963 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
2970 /* Try to register an edge assertion for SSA name NAME on edge E for
2971 the condition COND contributing to the conditional jump pointed to by SI.
2972 Return true if an assertion for NAME could be registered. */
2975 register_edge_assert_for (tree name, edge e, block_stmt_iterator si, tree cond)
2978 enum tree_code comp_code;
2979 bool retval = false;
2980 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
2982 /* Do not attempt to infer anything in names that flow through
2984 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
2987 if (!extract_code_and_val_from_cond (name, cond, is_else_edge,
2991 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
2992 reachable from E. */
2993 if (TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
2995 register_new_assert_for (name, comp_code, val, NULL, e, si);
2999 /* If COND is effectively an equality test of an SSA_NAME against
3000 the value zero or one, then we may be able to assert values
3001 for SSA_NAMEs which flow into COND. */
3003 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
3004 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
3005 have nonzero value. */
3006 if (((comp_code == EQ_EXPR && integer_onep (val))
3007 || (comp_code == NE_EXPR && integer_zerop (val))))
3009 tree def_stmt = SSA_NAME_DEF_STMT (name);
3011 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3012 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_AND_EXPR
3013 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_AND_EXPR))
3015 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3016 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3017 retval |= register_edge_assert_for_1 (op0, NE_EXPR, e, si);
3018 retval |= register_edge_assert_for_1 (op1, NE_EXPR, e, si);
3022 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
3023 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
3025 if (((comp_code == EQ_EXPR && integer_zerop (val))
3026 || (comp_code == NE_EXPR && integer_onep (val))))
3028 tree def_stmt = SSA_NAME_DEF_STMT (name);
3030 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3031 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_OR_EXPR
3032 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_IOR_EXPR))
3034 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3035 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3036 retval |= register_edge_assert_for_1 (op0, EQ_EXPR, e, si);
3037 retval |= register_edge_assert_for_1 (op1, EQ_EXPR, e, si);
3045 static bool find_assert_locations (basic_block bb);
3047 /* Determine whether the outgoing edges of BB should receive an
3048 ASSERT_EXPR for each of the operands of BB's LAST statement.
3049 The last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
3051 If any of the sub-graphs rooted at BB have an interesting use of
3052 the predicate operands, an assert location node is added to the
3053 list of assertions for the corresponding operands. */
3056 find_conditional_asserts (basic_block bb, tree last)
3059 block_stmt_iterator bsi;
3065 need_assert = false;
3066 bsi = bsi_for_stmt (last);
3068 /* Look for uses of the operands in each of the sub-graphs
3069 rooted at BB. We need to check each of the outgoing edges
3070 separately, so that we know what kind of ASSERT_EXPR to
3072 FOR_EACH_EDGE (e, ei, bb->succs)
3077 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
3078 Otherwise, when we finish traversing each of the sub-graphs, we
3079 won't know whether the variables were found in the sub-graphs or
3080 if they had been found in a block upstream from BB.
3082 This is actually a bad idea is some cases, particularly jump
3083 threading. Consider a CFG like the following:
3093 Assume that one or more operands in the conditional at the
3094 end of block 0 are used in a conditional in block 2, but not
3095 anywhere in block 1. In this case we will not insert any
3096 assert statements in block 1, which may cause us to miss
3097 opportunities to optimize, particularly for jump threading. */
3098 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3099 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3101 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3102 to determine if any of the operands in the conditional
3103 predicate are used. */
3105 need_assert |= find_assert_locations (e->dest);
3107 /* Register the necessary assertions for each operand in the
3108 conditional predicate. */
3109 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3110 need_assert |= register_edge_assert_for (op, e, bsi,
3111 COND_EXPR_COND (last));
3114 /* Finally, indicate that we have found the operands in the
3116 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3117 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3123 /* Traverse all the statements in block BB looking for statements that
3124 may generate useful assertions for the SSA names in their operand.
3125 If a statement produces a useful assertion A for name N_i, then the
3126 list of assertions already generated for N_i is scanned to
3127 determine if A is actually needed.
3129 If N_i already had the assertion A at a location dominating the
3130 current location, then nothing needs to be done. Otherwise, the
3131 new location for A is recorded instead.
3133 1- For every statement S in BB, all the variables used by S are
3134 added to bitmap FOUND_IN_SUBGRAPH.
3136 2- If statement S uses an operand N in a way that exposes a known
3137 value range for N, then if N was not already generated by an
3138 ASSERT_EXPR, create a new assert location for N. For instance,
3139 if N is a pointer and the statement dereferences it, we can
3140 assume that N is not NULL.
3142 3- COND_EXPRs are a special case of #2. We can derive range
3143 information from the predicate but need to insert different
3144 ASSERT_EXPRs for each of the sub-graphs rooted at the
3145 conditional block. If the last statement of BB is a conditional
3146 expression of the form 'X op Y', then
3148 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
3150 b) If the conditional is the only entry point to the sub-graph
3151 corresponding to the THEN_CLAUSE, recurse into it. On
3152 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
3153 an ASSERT_EXPR is added for the corresponding variable.
3155 c) Repeat step (b) on the ELSE_CLAUSE.
3157 d) Mark X and Y in FOUND_IN_SUBGRAPH.
3166 In this case, an assertion on the THEN clause is useful to
3167 determine that 'a' is always 9 on that edge. However, an assertion
3168 on the ELSE clause would be unnecessary.
3170 4- If BB does not end in a conditional expression, then we recurse
3171 into BB's dominator children.
3173 At the end of the recursive traversal, every SSA name will have a
3174 list of locations where ASSERT_EXPRs should be added. When a new
3175 location for name N is found, it is registered by calling
3176 register_new_assert_for. That function keeps track of all the
3177 registered assertions to prevent adding unnecessary assertions.
3178 For instance, if a pointer P_4 is dereferenced more than once in a
3179 dominator tree, only the location dominating all the dereference of
3180 P_4 will receive an ASSERT_EXPR.
3182 If this function returns true, then it means that there are names
3183 for which we need to generate ASSERT_EXPRs. Those assertions are
3184 inserted by process_assert_insertions.
3186 TODO. Handle SWITCH_EXPR. */
3189 find_assert_locations (basic_block bb)
3191 block_stmt_iterator si;
3196 if (TEST_BIT (blocks_visited, bb->index))
3199 SET_BIT (blocks_visited, bb->index);
3201 need_assert = false;
3203 /* Traverse all PHI nodes in BB marking used operands. */
3204 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3206 use_operand_p arg_p;
3209 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
3211 tree arg = USE_FROM_PTR (arg_p);
3212 if (TREE_CODE (arg) == SSA_NAME)
3214 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
3215 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
3220 /* Traverse all the statements in BB marking used names and looking
3221 for statements that may infer assertions for their used operands. */
3223 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3228 stmt = bsi_stmt (si);
3230 /* See if we can derive an assertion for any of STMT's operands. */
3231 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
3234 enum tree_code comp_code;
3236 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
3237 the sub-graph of a conditional block, when we return from
3238 this recursive walk, our parent will use the
3239 FOUND_IN_SUBGRAPH bitset to determine if one of the
3240 operands it was looking for was present in the sub-graph. */
3241 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3243 /* If OP is used in such a way that we can infer a value
3244 range for it, and we don't find a previous assertion for
3245 it, create a new assertion location node for OP. */
3246 if (infer_value_range (stmt, op, &comp_code, &value))
3248 /* If we are able to infer a nonzero value range for OP,
3249 then walk backwards through the use-def chain to see if OP
3250 was set via a typecast.
3252 If so, then we can also infer a nonzero value range
3253 for the operand of the NOP_EXPR. */
3254 if (comp_code == NE_EXPR && integer_zerop (value))
3257 tree def_stmt = SSA_NAME_DEF_STMT (t);
3259 while (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3261 (GIMPLE_STMT_OPERAND (def_stmt, 1)) == NOP_EXPR
3263 (TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1),
3266 (TREE_TYPE (TREE_OPERAND
3267 (GIMPLE_STMT_OPERAND (def_stmt,
3270 t = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3271 def_stmt = SSA_NAME_DEF_STMT (t);
3273 /* Note we want to register the assert for the
3274 operand of the NOP_EXPR after SI, not after the
3276 if (! has_single_use (t))
3278 register_new_assert_for (t, comp_code, value,
3285 /* If OP is used only once, namely in this STMT, don't
3286 bother creating an ASSERT_EXPR for it. Such an
3287 ASSERT_EXPR would do nothing but increase compile time. */
3288 if (!has_single_use (op))
3290 register_new_assert_for (op, comp_code, value, bb, NULL, si);
3296 /* Remember the last statement of the block. */
3300 /* If BB's last statement is a conditional expression
3301 involving integer operands, recurse into each of the sub-graphs
3302 rooted at BB to determine if we need to add ASSERT_EXPRs. */
3304 && TREE_CODE (last) == COND_EXPR
3305 && !fp_predicate (COND_EXPR_COND (last))
3306 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
3307 need_assert |= find_conditional_asserts (bb, last);
3309 /* Recurse into the dominator children of BB. */
3310 for (son = first_dom_son (CDI_DOMINATORS, bb);
3312 son = next_dom_son (CDI_DOMINATORS, son))
3313 need_assert |= find_assert_locations (son);
3319 /* Create an ASSERT_EXPR for NAME and insert it in the location
3320 indicated by LOC. Return true if we made any edge insertions. */
3323 process_assert_insertions_for (tree name, assert_locus_t loc)
3325 /* Build the comparison expression NAME_i COMP_CODE VAL. */
3326 tree stmt, cond, assert_expr;
3330 cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
3331 assert_expr = build_assert_expr_for (cond, name);
3335 /* We have been asked to insert the assertion on an edge. This
3336 is used only by COND_EXPR and SWITCH_EXPR assertions. */
3337 #if defined ENABLE_CHECKING
3338 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
3339 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
3342 bsi_insert_on_edge (loc->e, assert_expr);
3346 /* Otherwise, we can insert right after LOC->SI iff the
3347 statement must not be the last statement in the block. */
3348 stmt = bsi_stmt (loc->si);
3349 if (!stmt_ends_bb_p (stmt))
3351 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
3355 /* If STMT must be the last statement in BB, we can only insert new
3356 assertions on the non-abnormal edge out of BB. Note that since
3357 STMT is not control flow, there may only be one non-abnormal edge
3359 FOR_EACH_EDGE (e, ei, loc->bb->succs)
3360 if (!(e->flags & EDGE_ABNORMAL))
3362 bsi_insert_on_edge (e, assert_expr);
3370 /* Process all the insertions registered for every name N_i registered
3371 in NEED_ASSERT_FOR. The list of assertions to be inserted are
3372 found in ASSERTS_FOR[i]. */
3375 process_assert_insertions (void)
3379 bool update_edges_p = false;
3380 int num_asserts = 0;
3382 if (dump_file && (dump_flags & TDF_DETAILS))
3383 dump_all_asserts (dump_file);
3385 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3387 assert_locus_t loc = asserts_for[i];
3392 assert_locus_t next = loc->next;
3393 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
3401 bsi_commit_edge_inserts ();
3403 if (dump_file && (dump_flags & TDF_STATS))
3404 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
3409 /* Traverse the flowgraph looking for conditional jumps to insert range
3410 expressions. These range expressions are meant to provide information
3411 to optimizations that need to reason in terms of value ranges. They
3412 will not be expanded into RTL. For instance, given:
3421 this pass will transform the code into:
3427 x = ASSERT_EXPR <x, x < y>
3432 y = ASSERT_EXPR <y, x <= y>
3436 The idea is that once copy and constant propagation have run, other
3437 optimizations will be able to determine what ranges of values can 'x'
3438 take in different paths of the code, simply by checking the reaching
3439 definition of 'x'. */
3442 insert_range_assertions (void)
3448 found_in_subgraph = sbitmap_alloc (num_ssa_names);
3449 sbitmap_zero (found_in_subgraph);
3451 blocks_visited = sbitmap_alloc (last_basic_block);
3452 sbitmap_zero (blocks_visited);
3454 need_assert_for = BITMAP_ALLOC (NULL);
3455 asserts_for = XCNEWVEC (assert_locus_t, num_ssa_names);
3457 calculate_dominance_info (CDI_DOMINATORS);
3459 update_ssa_p = false;
3460 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3461 if (find_assert_locations (e->dest))
3462 update_ssa_p = true;
3466 process_assert_insertions ();
3467 update_ssa (TODO_update_ssa_no_phi);
3470 if (dump_file && (dump_flags & TDF_DETAILS))
3472 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
3473 dump_function_to_file (current_function_decl, dump_file, dump_flags);
3476 sbitmap_free (found_in_subgraph);
3478 BITMAP_FREE (need_assert_for);
3482 /* Convert range assertion expressions into the implied copies and
3483 copy propagate away the copies. Doing the trivial copy propagation
3484 here avoids the need to run the full copy propagation pass after
3487 FIXME, this will eventually lead to copy propagation removing the
3488 names that had useful range information attached to them. For
3489 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
3490 then N_i will have the range [3, +INF].
3492 However, by converting the assertion into the implied copy
3493 operation N_i = N_j, we will then copy-propagate N_j into the uses
3494 of N_i and lose the range information. We may want to hold on to
3495 ASSERT_EXPRs a little while longer as the ranges could be used in
3496 things like jump threading.
3498 The problem with keeping ASSERT_EXPRs around is that passes after
3499 VRP need to handle them appropriately.
3501 Another approach would be to make the range information a first
3502 class property of the SSA_NAME so that it can be queried from
3503 any pass. This is made somewhat more complex by the need for
3504 multiple ranges to be associated with one SSA_NAME. */
3507 remove_range_assertions (void)
3510 block_stmt_iterator si;
3512 /* Note that the BSI iterator bump happens at the bottom of the
3513 loop and no bump is necessary if we're removing the statement
3514 referenced by the current BSI. */
3516 for (si = bsi_start (bb); !bsi_end_p (si);)
3518 tree stmt = bsi_stmt (si);
3521 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
3522 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ASSERT_EXPR)
3524 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1), var;
3525 tree cond = fold (ASSERT_EXPR_COND (rhs));
3526 use_operand_p use_p;
3527 imm_use_iterator iter;
3529 gcc_assert (cond != boolean_false_node);
3531 /* Propagate the RHS into every use of the LHS. */
3532 var = ASSERT_EXPR_VAR (rhs);
3533 FOR_EACH_IMM_USE_STMT (use_stmt, iter,
3534 GIMPLE_STMT_OPERAND (stmt, 0))
3535 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
3537 SET_USE (use_p, var);
3538 gcc_assert (TREE_CODE (var) == SSA_NAME);
3541 /* And finally, remove the copy, it is not needed. */
3542 bsi_remove (&si, true);
3548 sbitmap_free (blocks_visited);
3552 /* Return true if STMT is interesting for VRP. */
3555 stmt_interesting_for_vrp (tree stmt)
3557 if (TREE_CODE (stmt) == PHI_NODE
3558 && is_gimple_reg (PHI_RESULT (stmt))
3559 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
3560 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
3562 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
3564 tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
3565 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
3567 /* In general, assignments with virtual operands are not useful
3568 for deriving ranges, with the obvious exception of calls to
3569 builtin functions. */
3570 if (TREE_CODE (lhs) == SSA_NAME
3571 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3572 || POINTER_TYPE_P (TREE_TYPE (lhs)))
3573 && ((TREE_CODE (rhs) == CALL_EXPR
3574 && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR
3575 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))
3576 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)))
3577 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)))
3580 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3587 /* Initialize local data structures for VRP. */
3590 vrp_initialize (void)
3594 vr_value = XCNEWVEC (value_range_t *, num_ssa_names);
3598 block_stmt_iterator si;
3601 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3603 if (!stmt_interesting_for_vrp (phi))
3605 tree lhs = PHI_RESULT (phi);
3606 set_value_range_to_varying (get_value_range (lhs));
3607 DONT_SIMULATE_AGAIN (phi) = true;
3610 DONT_SIMULATE_AGAIN (phi) = false;
3613 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3615 tree stmt = bsi_stmt (si);
3617 if (!stmt_interesting_for_vrp (stmt))
3621 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
3622 set_value_range_to_varying (get_value_range (def));
3623 DONT_SIMULATE_AGAIN (stmt) = true;
3627 DONT_SIMULATE_AGAIN (stmt) = false;
3634 /* Visit assignment STMT. If it produces an interesting range, record
3635 the SSA name in *OUTPUT_P. */
3637 static enum ssa_prop_result
3638 vrp_visit_assignment (tree stmt, tree *output_p)
3643 lhs = GIMPLE_STMT_OPERAND (stmt, 0);
3644 rhs = GIMPLE_STMT_OPERAND (stmt, 1);
3646 /* We only keep track of ranges in integral and pointer types. */
3647 if (TREE_CODE (lhs) == SSA_NAME
3648 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3649 /* It is valid to have NULL MIN/MAX values on a type. See
3650 build_range_type. */
3651 && TYPE_MIN_VALUE (TREE_TYPE (lhs))
3652 && TYPE_MAX_VALUE (TREE_TYPE (lhs)))
3653 || POINTER_TYPE_P (TREE_TYPE (lhs))))
3656 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3658 extract_range_from_expr (&new_vr, rhs);
3660 /* If STMT is inside a loop, we may be able to know something
3661 else about the range of LHS by examining scalar evolution
3663 if (current_loops && (l = loop_containing_stmt (stmt)))
3664 adjust_range_with_scev (&new_vr, l, stmt, lhs);
3666 if (update_value_range (lhs, &new_vr))
3670 if (dump_file && (dump_flags & TDF_DETAILS))
3672 fprintf (dump_file, "Found new range for ");
3673 print_generic_expr (dump_file, lhs, 0);
3674 fprintf (dump_file, ": ");
3675 dump_value_range (dump_file, &new_vr);
3676 fprintf (dump_file, "\n\n");
3679 if (new_vr.type == VR_VARYING)
3680 return SSA_PROP_VARYING;
3682 return SSA_PROP_INTERESTING;
3685 return SSA_PROP_NOT_INTERESTING;
3688 /* Every other statement produces no useful ranges. */
3689 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3690 set_value_range_to_varying (get_value_range (def));
3692 return SSA_PROP_VARYING;
3696 /* Compare all the value ranges for names equivalent to VAR with VAL
3697 using comparison code COMP. Return the same value returned by
3698 compare_range_with_value. */
3701 compare_name_with_value (enum tree_code comp, tree var, tree val)
3708 t = retval = NULL_TREE;
3710 /* Get the set of equivalences for VAR. */
3711 e = get_value_range (var)->equiv;
3713 /* Add VAR to its own set of equivalences so that VAR's value range
3714 is processed by this loop (otherwise, we would have to replicate
3715 the body of the loop just to check VAR's value range). */
3716 bitmap_set_bit (e, SSA_NAME_VERSION (var));
3718 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
3720 value_range_t equiv_vr = *(vr_value[i]);
3722 /* If name N_i does not have a valid range, use N_i as its own
3723 range. This allows us to compare against names that may
3724 have N_i in their ranges. */
3725 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
3727 equiv_vr.type = VR_RANGE;
3728 equiv_vr.min = ssa_name (i);
3729 equiv_vr.max = ssa_name (i);
3732 t = compare_range_with_value (comp, &equiv_vr, val);
3735 /* If we get different answers from different members
3736 of the equivalence set this check must be in a dead
3737 code region. Folding it to a trap representation
3738 would be correct here. For now just return don't-know. */
3749 /* Remove VAR from its own equivalence set. */
3750 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
3755 /* We couldn't find a non-NULL value for the predicate. */
3760 /* Given a comparison code COMP and names N1 and N2, compare all the
3761 ranges equivalent to N1 against all the ranges equivalent to N2
3762 to determine the value of N1 COMP N2. Return the same value
3763 returned by compare_ranges. */
3766 compare_names (enum tree_code comp, tree n1, tree n2)
3770 bitmap_iterator bi1, bi2;
3773 /* Compare the ranges of every name equivalent to N1 against the
3774 ranges of every name equivalent to N2. */
3775 e1 = get_value_range (n1)->equiv;
3776 e2 = get_value_range (n2)->equiv;
3778 /* Add N1 and N2 to their own set of equivalences to avoid
3779 duplicating the body of the loop just to check N1 and N2
3781 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
3782 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
3784 /* If the equivalence sets have a common intersection, then the two
3785 names can be compared without checking their ranges. */
3786 if (bitmap_intersect_p (e1, e2))
3788 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3789 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3791 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
3793 : boolean_false_node;
3796 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3797 N2 to their own set of equivalences to avoid duplicating the body
3798 of the loop just to check N1 and N2 ranges. */
3799 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
3801 value_range_t vr1 = *(vr_value[i1]);
3803 /* If the range is VARYING or UNDEFINED, use the name itself. */
3804 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
3806 vr1.type = VR_RANGE;
3807 vr1.min = ssa_name (i1);
3808 vr1.max = ssa_name (i1);
3811 t = retval = NULL_TREE;
3812 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
3814 value_range_t vr2 = *(vr_value[i2]);
3816 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
3818 vr2.type = VR_RANGE;
3819 vr2.min = ssa_name (i2);
3820 vr2.max = ssa_name (i2);
3823 t = compare_ranges (comp, &vr1, &vr2);
3826 /* If we get different answers from different members
3827 of the equivalence set this check must be in a dead
3828 code region. Folding it to a trap representation
3829 would be correct here. For now just return don't-know. */
3833 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3834 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3843 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3844 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3849 /* None of the equivalent ranges are useful in computing this
3851 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3852 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3857 /* Given a conditional predicate COND, try to determine if COND yields
3858 true or false based on the value ranges of its operands. Return
3859 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3860 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3861 NULL if the conditional cannot be evaluated at compile time.
3863 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3864 the operands in COND are used when trying to compute its value.
3865 This is only used during final substitution. During propagation,
3866 we only check the range of each variable and not its equivalents. */
3869 vrp_evaluate_conditional (tree cond, bool use_equiv_p)
3871 gcc_assert (TREE_CODE (cond) == SSA_NAME
3872 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
3874 if (TREE_CODE (cond) == SSA_NAME)
3880 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node);
3883 value_range_t *vr = get_value_range (cond);
3884 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node);
3887 /* If COND has a known boolean range, return it. */
3891 /* Otherwise, if COND has a symbolic range of exactly one value,
3893 vr = get_value_range (cond);
3894 if (vr->type == VR_RANGE && vr->min == vr->max)
3899 tree op0 = TREE_OPERAND (cond, 0);
3900 tree op1 = TREE_OPERAND (cond, 1);
3902 /* We only deal with integral and pointer types. */
3903 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
3904 && !POINTER_TYPE_P (TREE_TYPE (op0)))
3909 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
3910 return compare_names (TREE_CODE (cond), op0, op1);
3911 else if (TREE_CODE (op0) == SSA_NAME)
3912 return compare_name_with_value (TREE_CODE (cond), op0, op1);
3913 else if (TREE_CODE (op1) == SSA_NAME)
3914 return compare_name_with_value (
3915 swap_tree_comparison (TREE_CODE (cond)), op1, op0);
3919 value_range_t *vr0, *vr1;
3921 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
3922 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
3925 return compare_ranges (TREE_CODE (cond), vr0, vr1);
3926 else if (vr0 && vr1 == NULL)
3927 return compare_range_with_value (TREE_CODE (cond), vr0, op1);
3928 else if (vr0 == NULL && vr1)
3929 return compare_range_with_value (
3930 swap_tree_comparison (TREE_CODE (cond)), vr1, op0);
3934 /* Anything else cannot be computed statically. */
3939 /* Visit conditional statement STMT. If we can determine which edge
3940 will be taken out of STMT's basic block, record it in
3941 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3942 SSA_PROP_VARYING. */
3944 static enum ssa_prop_result
3945 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
3949 *taken_edge_p = NULL;
3951 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3952 add ASSERT_EXPRs for them. */
3953 if (TREE_CODE (stmt) == SWITCH_EXPR)
3954 return SSA_PROP_VARYING;
3956 cond = COND_EXPR_COND (stmt);
3958 if (dump_file && (dump_flags & TDF_DETAILS))
3963 fprintf (dump_file, "\nVisiting conditional with predicate: ");
3964 print_generic_expr (dump_file, cond, 0);
3965 fprintf (dump_file, "\nWith known ranges\n");
3967 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
3969 fprintf (dump_file, "\t");
3970 print_generic_expr (dump_file, use, 0);
3971 fprintf (dump_file, ": ");
3972 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
3975 fprintf (dump_file, "\n");
3978 /* Compute the value of the predicate COND by checking the known
3979 ranges of each of its operands.
3981 Note that we cannot evaluate all the equivalent ranges here
3982 because those ranges may not yet be final and with the current
3983 propagation strategy, we cannot determine when the value ranges
3984 of the names in the equivalence set have changed.
3986 For instance, given the following code fragment
3990 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3994 Assume that on the first visit to i_14, i_5 has the temporary
3995 range [8, 8] because the second argument to the PHI function is
3996 not yet executable. We derive the range ~[0, 0] for i_14 and the
3997 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3998 the first time, since i_14 is equivalent to the range [8, 8], we
3999 determine that the predicate is always false.
4001 On the next round of propagation, i_13 is determined to be
4002 VARYING, which causes i_5 to drop down to VARYING. So, another
4003 visit to i_14 is scheduled. In this second visit, we compute the
4004 exact same range and equivalence set for i_14, namely ~[0, 0] and
4005 { i_5 }. But we did not have the previous range for i_5
4006 registered, so vrp_visit_assignment thinks that the range for
4007 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
4008 is not visited again, which stops propagation from visiting
4009 statements in the THEN clause of that if().
4011 To properly fix this we would need to keep the previous range
4012 value for the names in the equivalence set. This way we would've
4013 discovered that from one visit to the other i_5 changed from
4014 range [8, 8] to VR_VARYING.
4016 However, fixing this apparent limitation may not be worth the
4017 additional checking. Testing on several code bases (GCC, DLV,
4018 MICO, TRAMP3D and SPEC2000) showed that doing this results in
4019 4 more predicates folded in SPEC. */
4020 val = vrp_evaluate_conditional (cond, false);
4022 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
4024 if (dump_file && (dump_flags & TDF_DETAILS))
4026 fprintf (dump_file, "\nPredicate evaluates to: ");
4027 if (val == NULL_TREE)
4028 fprintf (dump_file, "DON'T KNOW\n");
4030 print_generic_stmt (dump_file, val, 0);
4033 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
4037 /* Evaluate statement STMT. If the statement produces a useful range,
4038 return SSA_PROP_INTERESTING and record the SSA name with the
4039 interesting range into *OUTPUT_P.
4041 If STMT is a conditional branch and we can determine its truth
4042 value, the taken edge is recorded in *TAKEN_EDGE_P.
4044 If STMT produces a varying value, return SSA_PROP_VARYING. */
4046 static enum ssa_prop_result
4047 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
4053 if (dump_file && (dump_flags & TDF_DETAILS))
4055 fprintf (dump_file, "\nVisiting statement:\n");
4056 print_generic_stmt (dump_file, stmt, dump_flags);
4057 fprintf (dump_file, "\n");
4060 ann = stmt_ann (stmt);
4061 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4063 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4065 /* In general, assignments with virtual operands are not useful
4066 for deriving ranges, with the obvious exception of calls to
4067 builtin functions. */
4068 if ((TREE_CODE (rhs) == CALL_EXPR
4069 && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR
4070 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))
4071 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)))
4072 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
4073 return vrp_visit_assignment (stmt, output_p);
4075 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
4076 return vrp_visit_cond_stmt (stmt, taken_edge_p);
4078 /* All other statements produce nothing of interest for VRP, so mark
4079 their outputs varying and prevent further simulation. */
4080 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
4081 set_value_range_to_varying (get_value_range (def));
4083 return SSA_PROP_VARYING;
4087 /* Meet operation for value ranges. Given two value ranges VR0 and
4088 VR1, store in VR0 a range that contains both VR0 and VR1. This
4089 may not be the smallest possible such range. */
4092 vrp_meet (value_range_t *vr0, value_range_t *vr1)
4094 if (vr0->type == VR_UNDEFINED)
4096 copy_value_range (vr0, vr1);
4100 if (vr1->type == VR_UNDEFINED)
4102 /* Nothing to do. VR0 already has the resulting range. */
4106 if (vr0->type == VR_VARYING)
4108 /* Nothing to do. VR0 already has the resulting range. */
4112 if (vr1->type == VR_VARYING)
4114 set_value_range_to_varying (vr0);
4118 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
4123 /* Compute the convex hull of the ranges. The lower limit of
4124 the new range is the minimum of the two ranges. If they
4125 cannot be compared, then give up. */
4126 cmp = compare_values (vr0->min, vr1->min);
4127 if (cmp == 0 || cmp == 1)
4134 /* Similarly, the upper limit of the new range is the maximum
4135 of the two ranges. If they cannot be compared, then
4137 cmp = compare_values (vr0->max, vr1->max);
4138 if (cmp == 0 || cmp == -1)
4145 /* The resulting set of equivalences is the intersection of
4147 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4148 bitmap_and_into (vr0->equiv, vr1->equiv);
4149 else if (vr0->equiv && !vr1->equiv)
4150 bitmap_clear (vr0->equiv);
4152 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
4154 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
4156 /* Two anti-ranges meet only if their complements intersect.
4157 Only handle the case of identical ranges. */
4158 if (compare_values (vr0->min, vr1->min) == 0
4159 && compare_values (vr0->max, vr1->max) == 0
4160 && compare_values (vr0->min, vr0->max) == 0)
4162 /* The resulting set of equivalences is the intersection of
4164 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4165 bitmap_and_into (vr0->equiv, vr1->equiv);
4166 else if (vr0->equiv && !vr1->equiv)
4167 bitmap_clear (vr0->equiv);
4172 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
4174 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
4175 only handle the case where the ranges have an empty intersection.
4176 The result of the meet operation is the anti-range. */
4177 if (!symbolic_range_p (vr0)
4178 && !symbolic_range_p (vr1)
4179 && !value_ranges_intersect_p (vr0, vr1))
4181 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
4182 set. We need to compute the intersection of the two
4183 equivalence sets. */
4184 if (vr1->type == VR_ANTI_RANGE)
4185 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
4187 /* The resulting set of equivalences is the intersection of
4189 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4190 bitmap_and_into (vr0->equiv, vr1->equiv);
4191 else if (vr0->equiv && !vr1->equiv)
4192 bitmap_clear (vr0->equiv);
4203 /* Failed to find an efficient meet. Before giving up and setting
4204 the result to VARYING, see if we can at least derive a useful
4205 anti-range. FIXME, all this nonsense about distinguishing
4206 anti-ranges from ranges is necessary because of the odd
4207 semantics of range_includes_zero_p and friends. */
4208 if (!symbolic_range_p (vr0)
4209 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
4210 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
4211 && !symbolic_range_p (vr1)
4212 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
4213 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
4215 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
4217 /* Since this meet operation did not result from the meeting of
4218 two equivalent names, VR0 cannot have any equivalences. */
4220 bitmap_clear (vr0->equiv);
4223 set_value_range_to_varying (vr0);
4227 /* Visit all arguments for PHI node PHI that flow through executable
4228 edges. If a valid value range can be derived from all the incoming
4229 value ranges, set a new range for the LHS of PHI. */
4231 static enum ssa_prop_result
4232 vrp_visit_phi_node (tree phi)
4235 tree lhs = PHI_RESULT (phi);
4236 value_range_t *lhs_vr = get_value_range (lhs);
4237 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
4238 bool all_const = true;
4240 copy_value_range (&vr_result, lhs_vr);
4242 if (dump_file && (dump_flags & TDF_DETAILS))
4244 fprintf (dump_file, "\nVisiting PHI node: ");
4245 print_generic_expr (dump_file, phi, dump_flags);
4248 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
4250 edge e = PHI_ARG_EDGE (phi, i);
4252 if (dump_file && (dump_flags & TDF_DETAILS))
4255 "\n Argument #%d (%d -> %d %sexecutable)\n",
4256 i, e->src->index, e->dest->index,
4257 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
4260 if (e->flags & EDGE_EXECUTABLE)
4262 tree arg = PHI_ARG_DEF (phi, i);
4263 value_range_t vr_arg;
4265 if (TREE_CODE (arg) == SSA_NAME)
4267 vr_arg = *(get_value_range (arg));
4272 vr_arg.type = VR_RANGE;
4275 vr_arg.equiv = NULL;
4278 if (dump_file && (dump_flags & TDF_DETAILS))
4280 fprintf (dump_file, "\t");
4281 print_generic_expr (dump_file, arg, dump_flags);
4282 fprintf (dump_file, "\n\tValue: ");
4283 dump_value_range (dump_file, &vr_arg);
4284 fprintf (dump_file, "\n");
4287 vrp_meet (&vr_result, &vr_arg);
4289 if (vr_result.type == VR_VARYING)
4294 if (vr_result.type == VR_VARYING)
4297 /* To prevent infinite iterations in the algorithm, derive ranges
4298 when the new value is slightly bigger or smaller than the
4300 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE
4303 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
4305 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
4306 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
4308 /* If the new minimum is smaller or larger than the previous
4309 one, go all the way to -INF. In the first case, to avoid
4310 iterating millions of times to reach -INF, and in the
4311 other case to avoid infinite bouncing between different
4313 if (cmp_min > 0 || cmp_min < 0)
4314 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
4316 /* Similarly, if the new maximum is smaller or larger than
4317 the previous one, go all the way to +INF. */
4318 if (cmp_max < 0 || cmp_max > 0)
4319 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
4321 /* If we ended up with a (-INF, +INF) range, set it to
4323 if (vr_result.min == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))
4324 && vr_result.max == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)))
4329 /* If the new range is different than the previous value, keep
4331 if (update_value_range (lhs, &vr_result))
4332 return SSA_PROP_INTERESTING;
4334 /* Nothing changed, don't add outgoing edges. */
4335 return SSA_PROP_NOT_INTERESTING;
4337 /* No match found. Set the LHS to VARYING. */
4339 set_value_range_to_varying (lhs_vr);
4340 return SSA_PROP_VARYING;
4343 /* Simplify a division or modulo operator to a right shift or
4344 bitwise and if the first operand is unsigned or is greater
4345 than zero and the second operand is an exact power of two. */
4348 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
4351 tree op = TREE_OPERAND (rhs, 0);
4352 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
4354 if (TYPE_UNSIGNED (TREE_TYPE (op)))
4356 val = integer_one_node;
4360 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node);
4363 if (val && integer_onep (val))
4366 tree op0 = TREE_OPERAND (rhs, 0);
4367 tree op1 = TREE_OPERAND (rhs, 1);
4369 if (rhs_code == TRUNC_DIV_EXPR)
4371 t = build_int_cst (NULL_TREE, tree_log2 (op1));
4372 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
4376 t = build_int_cst (TREE_TYPE (op1), 1);
4377 t = int_const_binop (MINUS_EXPR, op1, t, 0);
4378 t = fold_convert (TREE_TYPE (op0), t);
4379 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
4382 GIMPLE_STMT_OPERAND (stmt, 1) = t;
4387 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
4388 ABS_EXPR. If the operand is <= 0, then simplify the
4389 ABS_EXPR into a NEGATE_EXPR. */
4392 simplify_abs_using_ranges (tree stmt, tree rhs)
4395 tree op = TREE_OPERAND (rhs, 0);
4396 tree type = TREE_TYPE (op);
4397 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
4399 if (TYPE_UNSIGNED (type))
4401 val = integer_zero_node;
4405 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node);
4408 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node);
4412 if (integer_zerop (val))
4413 val = integer_one_node;
4414 else if (integer_onep (val))
4415 val = integer_zero_node;
4420 && (integer_onep (val) || integer_zerop (val)))
4424 if (integer_onep (val))
4425 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
4429 GIMPLE_STMT_OPERAND (stmt, 1) = t;
4435 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
4436 a known value range VR.
4438 If there is one and only one value which will satisfy the
4439 conditional, then return that value. Else return NULL. */
4442 test_for_singularity (enum tree_code cond_code, tree op0,
4443 tree op1, value_range_t *vr)
4448 /* Extract minimum/maximum values which satisfy the
4449 the conditional as it was written. */
4450 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
4452 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
4455 if (cond_code == LT_EXPR)
4457 tree one = build_int_cst (TREE_TYPE (op0), 1);
4458 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
4461 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
4463 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
4466 if (cond_code == GT_EXPR)
4468 tree one = build_int_cst (TREE_TYPE (op0), 1);
4469 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
4473 /* Now refine the minimum and maximum values using any
4474 value range information we have for op0. */
4477 if (compare_values (vr->min, min) == -1)
4481 if (compare_values (vr->max, max) == 1)
4486 /* If the new min/max values have converged to a single value,
4487 then there is only one value which can satisfy the condition,
4488 return that value. */
4489 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
4495 /* Simplify a conditional using a relational operator to an equality
4496 test if the range information indicates only one value can satisfy
4497 the original conditional. */
4500 simplify_cond_using_ranges (tree stmt)
4502 tree cond = COND_EXPR_COND (stmt);
4503 tree op0 = TREE_OPERAND (cond, 0);
4504 tree op1 = TREE_OPERAND (cond, 1);
4505 enum tree_code cond_code = TREE_CODE (cond);
4507 if (cond_code != NE_EXPR
4508 && cond_code != EQ_EXPR
4509 && TREE_CODE (op0) == SSA_NAME
4510 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
4511 && is_gimple_min_invariant (op1))
4513 value_range_t *vr = get_value_range (op0);
4515 /* If we have range information for OP0, then we might be
4516 able to simplify this conditional. */
4517 if (vr->type == VR_RANGE)
4519 tree new = test_for_singularity (cond_code, op0, op1, vr);
4525 fprintf (dump_file, "Simplified relational ");
4526 print_generic_expr (dump_file, cond, 0);
4527 fprintf (dump_file, " into ");
4530 COND_EXPR_COND (stmt)
4531 = build2 (EQ_EXPR, boolean_type_node, op0, new);
4536 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4537 fprintf (dump_file, "\n");
4543 /* Try again after inverting the condition. We only deal
4544 with integral types here, so no need to worry about
4545 issues with inverting FP comparisons. */
4546 cond_code = invert_tree_comparison (cond_code, false);
4547 new = test_for_singularity (cond_code, op0, op1, vr);
4553 fprintf (dump_file, "Simplified relational ");
4554 print_generic_expr (dump_file, cond, 0);
4555 fprintf (dump_file, " into ");
4558 COND_EXPR_COND (stmt)
4559 = build2 (NE_EXPR, boolean_type_node, op0, new);
4564 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4565 fprintf (dump_file, "\n");
4574 /* Simplify STMT using ranges if possible. */
4577 simplify_stmt_using_ranges (tree stmt)
4579 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4581 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4582 enum tree_code rhs_code = TREE_CODE (rhs);
4584 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
4585 and BIT_AND_EXPR respectively if the first operand is greater
4586 than zero and the second operand is an exact power of two. */
4587 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
4588 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
4589 && integer_pow2p (TREE_OPERAND (rhs, 1)))
4590 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
4592 /* Transform ABS (X) into X or -X as appropriate. */
4593 if (rhs_code == ABS_EXPR
4594 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
4595 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
4596 simplify_abs_using_ranges (stmt, rhs);
4598 else if (TREE_CODE (stmt) == COND_EXPR
4599 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
4601 simplify_cond_using_ranges (stmt);
4605 /* Stack of dest,src equivalency pairs that need to be restored after
4606 each attempt to thread a block's incoming edge to an outgoing edge.
4608 A NULL entry is used to mark the end of pairs which need to be
4610 static VEC(tree,heap) *stack;
4612 /* A trivial wrapper so that we can present the generic jump
4613 threading code with a simple API for simplifying statements. */
4615 simplify_stmt_for_jump_threading (tree stmt)
4617 /* We only use VRP information to simplify conditionals. This is
4618 overly conservative, but it's unclear if doing more would be
4619 worth the compile time cost. */
4620 if (TREE_CODE (stmt) != COND_EXPR)
4623 return vrp_evaluate_conditional (COND_EXPR_COND (stmt), true);
4626 /* Blocks which have more than one predecessor and more than
4627 one successor present jump threading opportunities. ie,
4628 when the block is reached from a specific predecessor, we
4629 may be able to determine which of the outgoing edges will
4630 be traversed. When this optimization applies, we are able
4631 to avoid conditionals at runtime and we may expose secondary
4632 optimization opportunities.
4634 This routine is effectively a driver for the generic jump
4635 threading code. It basically just presents the generic code
4636 with edges that may be suitable for jump threading.
4638 Unlike DOM, we do not iterate VRP if jump threading was successful.
4639 While iterating may expose new opportunities for VRP, it is expected
4640 those opportunities would be very limited and the compile time cost
4641 to expose those opportunities would be significant.
4643 As jump threading opportunities are discovered, they are registered
4644 for later realization. */
4647 identify_jump_threads (void)
4652 /* Ugh. When substituting values earlier in this pass we can
4653 wipe the dominance information. So rebuild the dominator
4654 information as we need it within the jump threading code. */
4655 calculate_dominance_info (CDI_DOMINATORS);
4657 /* We do not allow VRP information to be used for jump threading
4658 across a back edge in the CFG. Otherwise it becomes too
4659 difficult to avoid eliminating loop exit tests. Of course
4660 EDGE_DFS_BACK is not accurate at this time so we have to
4662 mark_dfs_back_edges ();
4664 /* Allocate our unwinder stack to unwind any temporary equivalences
4665 that might be recorded. */
4666 stack = VEC_alloc (tree, heap, 20);
4668 /* To avoid lots of silly node creation, we create a single
4669 conditional and just modify it in-place when attempting to
4671 dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL);
4672 dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL);
4674 /* Walk through all the blocks finding those which present a
4675 potential jump threading opportunity. We could set this up
4676 as a dominator walker and record data during the walk, but
4677 I doubt it's worth the effort for the classes of jump
4678 threading opportunities we are trying to identify at this
4679 point in compilation. */
4684 /* If the generic jump threading code does not find this block
4685 interesting, then there is nothing to do. */
4686 if (! potentially_threadable_block (bb))
4689 /* We only care about blocks ending in a COND_EXPR. While there
4690 may be some value in handling SWITCH_EXPR here, I doubt it's
4691 terribly important. */
4692 last = bsi_stmt (bsi_last (bb));
4693 if (TREE_CODE (last) != COND_EXPR)
4696 /* We're basically looking for any kind of conditional with
4697 integral type arguments. */
4698 cond = COND_EXPR_COND (last);
4699 if ((TREE_CODE (cond) == SSA_NAME
4700 && INTEGRAL_TYPE_P (TREE_TYPE (cond)))
4701 || (COMPARISON_CLASS_P (cond)
4702 && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
4703 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0)))
4704 && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME
4705 || is_gimple_min_invariant (TREE_OPERAND (cond, 1)))
4706 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
4711 /* We've got a block with multiple predecessors and multiple
4712 successors which also ends in a suitable conditional. For
4713 each predecessor, see if we can thread it to a specific
4715 FOR_EACH_EDGE (e, ei, bb->preds)
4717 /* Do not thread across back edges or abnormal edges
4719 if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
4722 thread_across_edge (dummy, e, true,
4724 simplify_stmt_for_jump_threading);
4729 /* We do not actually update the CFG or SSA graphs at this point as
4730 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
4731 handle ASSERT_EXPRs gracefully. */
4734 /* We identified all the jump threading opportunities earlier, but could
4735 not transform the CFG at that time. This routine transforms the
4736 CFG and arranges for the dominator tree to be rebuilt if necessary.
4738 Note the SSA graph update will occur during the normal TODO
4739 processing by the pass manager. */
4741 finalize_jump_threads (void)
4743 bool cfg_altered = false;
4744 cfg_altered = thread_through_all_blocks ();
4746 /* If we threaded jumps, then we need to recompute the dominance
4747 information, to safely do that we must clean up the CFG first. */
4750 free_dominance_info (CDI_DOMINATORS);
4751 cleanup_tree_cfg ();
4752 calculate_dominance_info (CDI_DOMINATORS);
4754 VEC_free (tree, heap, stack);
4758 /* Traverse all the blocks folding conditionals with known ranges. */
4764 prop_value_t *single_val_range;
4765 bool do_value_subst_p;
4769 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
4770 dump_all_value_ranges (dump_file);
4771 fprintf (dump_file, "\n");
4774 /* We may have ended with ranges that have exactly one value. Those
4775 values can be substituted as any other copy/const propagated
4776 value using substitute_and_fold. */
4777 single_val_range = XCNEWVEC (prop_value_t, num_ssa_names);
4779 do_value_subst_p = false;
4780 for (i = 0; i < num_ssa_names; i++)
4782 && vr_value[i]->type == VR_RANGE
4783 && vr_value[i]->min == vr_value[i]->max)
4785 single_val_range[i].value = vr_value[i]->min;
4786 do_value_subst_p = true;
4789 if (!do_value_subst_p)
4791 /* We found no single-valued ranges, don't waste time trying to
4792 do single value substitution in substitute_and_fold. */
4793 free (single_val_range);
4794 single_val_range = NULL;
4797 substitute_and_fold (single_val_range, true);
4799 /* We must identify jump threading opportunities before we release
4800 the datastructures built by VRP. */
4801 identify_jump_threads ();
4803 /* Free allocated memory. */
4804 for (i = 0; i < num_ssa_names; i++)
4807 BITMAP_FREE (vr_value[i]->equiv);
4811 free (single_val_range);
4814 /* So that we can distinguish between VRP data being available
4815 and not available. */
4820 /* Main entry point to VRP (Value Range Propagation). This pass is
4821 loosely based on J. R. C. Patterson, ``Accurate Static Branch
4822 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
4823 Programming Language Design and Implementation, pp. 67-78, 1995.
4824 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
4826 This is essentially an SSA-CCP pass modified to deal with ranges
4827 instead of constants.
4829 While propagating ranges, we may find that two or more SSA name
4830 have equivalent, though distinct ranges. For instance,
4833 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
4835 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
4839 In the code above, pointer p_5 has range [q_2, q_2], but from the
4840 code we can also determine that p_5 cannot be NULL and, if q_2 had
4841 a non-varying range, p_5's range should also be compatible with it.
4843 These equivalences are created by two expressions: ASSERT_EXPR and
4844 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
4845 result of another assertion, then we can use the fact that p_5 and
4846 p_4 are equivalent when evaluating p_5's range.
4848 Together with value ranges, we also propagate these equivalences
4849 between names so that we can take advantage of information from
4850 multiple ranges when doing final replacement. Note that this
4851 equivalency relation is transitive but not symmetric.
4853 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
4854 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
4855 in contexts where that assertion does not hold (e.g., in line 6).
4857 TODO, the main difference between this pass and Patterson's is that
4858 we do not propagate edge probabilities. We only compute whether
4859 edges can be taken or not. That is, instead of having a spectrum
4860 of jump probabilities between 0 and 1, we only deal with 0, 1 and
4861 DON'T KNOW. In the future, it may be worthwhile to propagate
4862 probabilities to aid branch prediction. */
4867 insert_range_assertions ();
4869 loop_optimizer_init (LOOPS_NORMAL);
4874 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
4880 loop_optimizer_finalize ();
4883 /* ASSERT_EXPRs must be removed before finalizing jump threads
4884 as finalizing jump threads calls the CFG cleanup code which
4885 does not properly handle ASSERT_EXPRs. */
4886 remove_range_assertions ();
4888 /* If we exposed any new variables, go ahead and put them into
4889 SSA form now, before we handle jump threading. This simplifies
4890 interactions between rewriting of _DECL nodes into SSA form
4891 and rewriting SSA_NAME nodes into SSA form after block
4892 duplication and CFG manipulation. */
4893 update_ssa (TODO_update_ssa);
4895 finalize_jump_threads ();
4902 return flag_tree_vrp != 0;
4905 struct tree_opt_pass pass_vrp =
4908 gate_vrp, /* gate */
4909 execute_vrp, /* execute */
4912 0, /* static_pass_number */
4913 TV_TREE_VRP, /* tv_id */
4914 PROP_ssa | PROP_alias, /* properties_required */
4915 0, /* properties_provided */
4916 0, /* properties_destroyed */
4917 0, /* todo_flags_start */
4923 | TODO_update_smt_usage, /* todo_flags_finish */