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);
47 /* Location information for ASSERT_EXPRs. Each instance of this
48 structure describes an ASSERT_EXPR for an SSA name. Since a single
49 SSA name may have more than one assertion associated with it, these
50 locations are kept in a linked list attached to the corresponding
54 /* Basic block where the assertion would be inserted. */
57 /* Some assertions need to be inserted on an edge (e.g., assertions
58 generated by COND_EXPRs). In those cases, BB will be NULL. */
61 /* Pointer to the statement that generated this assertion. */
62 block_stmt_iterator si;
64 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
65 enum tree_code comp_code;
67 /* Value being compared against. */
70 /* Next node in the linked list. */
71 struct assert_locus_d *next;
74 typedef struct assert_locus_d *assert_locus_t;
76 /* If bit I is present, it means that SSA name N_i has a list of
77 assertions that should be inserted in the IL. */
78 static bitmap need_assert_for;
80 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
81 holds a list of ASSERT_LOCUS_T nodes that describe where
82 ASSERT_EXPRs for SSA name N_I should be inserted. */
83 static assert_locus_t *asserts_for;
85 /* Set of blocks visited in find_assert_locations. Used to avoid
86 visiting the same block more than once. */
87 static sbitmap blocks_visited;
89 /* Value range array. After propagation, VR_VALUE[I] holds the range
90 of values that SSA name N_I may take. */
91 static value_range_t **vr_value;
94 /* Return true if ARG is marked with the nonnull attribute in the
95 current function signature. */
98 nonnull_arg_p (tree arg)
100 tree t, attrs, fntype;
101 unsigned HOST_WIDE_INT arg_num;
103 gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
105 /* The static chain decl is always non null. */
106 if (arg == cfun->static_chain_decl)
109 fntype = TREE_TYPE (current_function_decl);
110 attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype));
112 /* If "nonnull" wasn't specified, we know nothing about the argument. */
113 if (attrs == NULL_TREE)
116 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
117 if (TREE_VALUE (attrs) == NULL_TREE)
120 /* Get the position number for ARG in the function signature. */
121 for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl);
123 t = TREE_CHAIN (t), arg_num++)
129 gcc_assert (t == arg);
131 /* Now see if ARG_NUM is mentioned in the nonnull list. */
132 for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
134 if (compare_tree_int (TREE_VALUE (t), arg_num) == 0)
142 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
145 set_value_range (value_range_t *vr, enum value_range_type t, tree min,
146 tree max, bitmap equiv)
148 #if defined ENABLE_CHECKING
149 /* Check the validity of the range. */
150 if (t == VR_RANGE || t == VR_ANTI_RANGE)
154 gcc_assert (min && max);
156 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
157 gcc_assert (min != TYPE_MIN_VALUE (TREE_TYPE (min))
158 || max != TYPE_MAX_VALUE (TREE_TYPE (max)));
160 cmp = compare_values (min, max);
161 gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
164 if (t == VR_UNDEFINED || t == VR_VARYING)
165 gcc_assert (min == NULL_TREE && max == NULL_TREE);
167 if (t == VR_UNDEFINED || t == VR_VARYING)
168 gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
175 /* Since updating the equivalence set involves deep copying the
176 bitmaps, only do it if absolutely necessary. */
177 if (vr->equiv == NULL)
178 vr->equiv = BITMAP_ALLOC (NULL);
180 if (equiv != vr->equiv)
182 if (equiv && !bitmap_empty_p (equiv))
183 bitmap_copy (vr->equiv, equiv);
185 bitmap_clear (vr->equiv);
190 /* Copy value range FROM into value range TO. */
193 copy_value_range (value_range_t *to, value_range_t *from)
195 set_value_range (to, from->type, from->min, from->max, from->equiv);
198 /* Set value range VR to a non-negative range of type TYPE. */
201 set_value_range_to_nonnegative (value_range_t *vr, tree type)
203 tree zero = build_int_cst (type, 0);
204 set_value_range (vr, VR_RANGE, zero, TYPE_MAX_VALUE (type), vr->equiv);
207 /* Set value range VR to a non-NULL range of type TYPE. */
210 set_value_range_to_nonnull (value_range_t *vr, tree type)
212 tree zero = build_int_cst (type, 0);
213 set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
217 /* Set value range VR to a NULL range of type TYPE. */
220 set_value_range_to_null (value_range_t *vr, tree type)
222 tree zero = build_int_cst (type, 0);
223 set_value_range (vr, VR_RANGE, zero, zero, vr->equiv);
227 /* Set value range VR to VR_VARYING. */
230 set_value_range_to_varying (value_range_t *vr)
232 vr->type = VR_VARYING;
233 vr->min = vr->max = NULL_TREE;
235 bitmap_clear (vr->equiv);
239 /* Set value range VR to a range of a truthvalue of type TYPE. */
242 set_value_range_to_truthvalue (value_range_t *vr, tree type)
244 if (TYPE_PRECISION (type) == 1)
245 set_value_range_to_varying (vr);
247 set_value_range (vr, VR_RANGE,
248 build_int_cst (type, 0), build_int_cst (type, 1),
253 /* Set value range VR to VR_UNDEFINED. */
256 set_value_range_to_undefined (value_range_t *vr)
258 vr->type = VR_UNDEFINED;
259 vr->min = vr->max = NULL_TREE;
261 bitmap_clear (vr->equiv);
265 /* Return value range information for VAR.
267 If we have no values ranges recorded (ie, VRP is not running), then
268 return NULL. Otherwise create an empty range if none existed for VAR. */
270 static value_range_t *
271 get_value_range (tree var)
275 unsigned ver = SSA_NAME_VERSION (var);
277 /* If we have no recorded ranges, then return NULL. */
285 /* Create a default value range. */
286 vr_value[ver] = vr = XCNEW (value_range_t);
288 /* Allocate an equivalence set. */
289 vr->equiv = BITMAP_ALLOC (NULL);
291 /* If VAR is a default definition, the variable can take any value
293 sym = SSA_NAME_VAR (var);
294 if (SSA_NAME_IS_DEFAULT_DEF (var))
296 /* Try to use the "nonnull" attribute to create ~[0, 0]
297 anti-ranges for pointers. Note that this is only valid with
298 default definitions of PARM_DECLs. */
299 if (TREE_CODE (sym) == PARM_DECL
300 && POINTER_TYPE_P (TREE_TYPE (sym))
301 && nonnull_arg_p (sym))
302 set_value_range_to_nonnull (vr, TREE_TYPE (sym));
304 set_value_range_to_varying (vr);
310 /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */
313 vrp_operand_equal_p (tree val1, tree val2)
317 && operand_equal_p (val1, val2, 0)));
320 /* Return true, if the bitmaps B1 and B2 are equal. */
323 vrp_bitmap_equal_p (bitmap b1, bitmap b2)
327 && bitmap_equal_p (b1, b2)));
330 /* Update the value range and equivalence set for variable VAR to
331 NEW_VR. Return true if NEW_VR is different from VAR's previous
334 NOTE: This function assumes that NEW_VR is a temporary value range
335 object created for the sole purpose of updating VAR's range. The
336 storage used by the equivalence set from NEW_VR will be freed by
337 this function. Do not call update_value_range when NEW_VR
338 is the range object associated with another SSA name. */
341 update_value_range (tree var, value_range_t *new_vr)
343 value_range_t *old_vr;
346 /* Update the value range, if necessary. */
347 old_vr = get_value_range (var);
348 is_new = old_vr->type != new_vr->type
349 || !vrp_operand_equal_p (old_vr->min, new_vr->min)
350 || !vrp_operand_equal_p (old_vr->max, new_vr->max)
351 || !vrp_bitmap_equal_p (old_vr->equiv, new_vr->equiv);
354 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
357 BITMAP_FREE (new_vr->equiv);
358 new_vr->equiv = NULL;
364 /* Add VAR and VAR's equivalence set to EQUIV. */
367 add_equivalence (bitmap equiv, tree var)
369 unsigned ver = SSA_NAME_VERSION (var);
370 value_range_t *vr = vr_value[ver];
372 bitmap_set_bit (equiv, ver);
374 bitmap_ior_into (equiv, vr->equiv);
378 /* Return true if VR is ~[0, 0]. */
381 range_is_nonnull (value_range_t *vr)
383 return vr->type == VR_ANTI_RANGE
384 && integer_zerop (vr->min)
385 && integer_zerop (vr->max);
389 /* Return true if VR is [0, 0]. */
392 range_is_null (value_range_t *vr)
394 return vr->type == VR_RANGE
395 && integer_zerop (vr->min)
396 && integer_zerop (vr->max);
400 /* Return true if value range VR involves at least one symbol. */
403 symbolic_range_p (value_range_t *vr)
405 return (!is_gimple_min_invariant (vr->min)
406 || !is_gimple_min_invariant (vr->max));
409 /* Like tree_expr_nonnegative_p, but this function uses value ranges
413 vrp_expr_computes_nonnegative (tree expr)
415 return tree_expr_nonnegative_p (expr);
418 /* Like tree_expr_nonzero_p, but this function uses value ranges
422 vrp_expr_computes_nonzero (tree expr)
424 if (tree_expr_nonzero_p (expr))
427 /* If we have an expression of the form &X->a, then the expression
428 is nonnull if X is nonnull. */
429 if (TREE_CODE (expr) == ADDR_EXPR)
431 tree base = get_base_address (TREE_OPERAND (expr, 0));
433 if (base != NULL_TREE
434 && TREE_CODE (base) == INDIRECT_REF
435 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
437 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
438 if (range_is_nonnull (vr))
446 /* Returns true if EXPR is a valid value (as expected by compare_values) --
447 a gimple invariant, or SSA_NAME +- CST. */
450 valid_value_p (tree expr)
452 if (TREE_CODE (expr) == SSA_NAME)
455 if (TREE_CODE (expr) == PLUS_EXPR
456 || TREE_CODE (expr) == MINUS_EXPR)
457 return (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME
458 && TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST);
460 return is_gimple_min_invariant (expr);
466 -2 if those are incomparable. */
468 operand_less_p (tree val, tree val2)
471 /* LT is folded faster than GE and others. Inline the common case. */
472 if (TREE_CODE (val) == INTEGER_CST && TREE_CODE (val2) == INTEGER_CST)
474 if (TYPE_UNSIGNED (TREE_TYPE (val)))
475 return INT_CST_LT_UNSIGNED (val, val2);
477 return INT_CST_LT (val, val2);
480 tcmp = fold_binary_to_constant (LT_EXPR, boolean_type_node, val, val2);
483 return !integer_zerop (tcmp);
486 /* Compare two values VAL1 and VAL2. Return
488 -2 if VAL1 and VAL2 cannot be compared at compile-time,
491 +1 if VAL1 > VAL2, and
494 This is similar to tree_int_cst_compare but supports pointer values
495 and values that cannot be compared at compile time. */
498 compare_values (tree val1, tree val2)
503 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
505 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
506 == POINTER_TYPE_P (TREE_TYPE (val2)));
508 if ((TREE_CODE (val1) == SSA_NAME
509 || TREE_CODE (val1) == PLUS_EXPR
510 || TREE_CODE (val1) == MINUS_EXPR)
511 && (TREE_CODE (val2) == SSA_NAME
512 || TREE_CODE (val2) == PLUS_EXPR
513 || TREE_CODE (val2) == MINUS_EXPR))
516 enum tree_code code1, code2;
518 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
519 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
520 same name, return -2. */
521 if (TREE_CODE (val1) == SSA_NAME)
529 code1 = TREE_CODE (val1);
530 n1 = TREE_OPERAND (val1, 0);
531 c1 = TREE_OPERAND (val1, 1);
532 if (tree_int_cst_sgn (c1) == -1)
534 c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1);
537 code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
541 if (TREE_CODE (val2) == SSA_NAME)
549 code2 = TREE_CODE (val2);
550 n2 = TREE_OPERAND (val2, 0);
551 c2 = TREE_OPERAND (val2, 1);
552 if (tree_int_cst_sgn (c2) == -1)
554 c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2);
557 code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
561 /* Both values must use the same name. */
565 if (code1 == SSA_NAME
566 && code2 == SSA_NAME)
570 /* If overflow is defined we cannot simplify more. */
571 if (TYPE_UNSIGNED (TREE_TYPE (val1))
575 if (code1 == SSA_NAME)
577 if (code2 == PLUS_EXPR)
578 /* NAME < NAME + CST */
580 else if (code2 == MINUS_EXPR)
581 /* NAME > NAME - CST */
584 else if (code1 == PLUS_EXPR)
586 if (code2 == SSA_NAME)
587 /* NAME + CST > NAME */
589 else if (code2 == PLUS_EXPR)
590 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
591 return compare_values (c1, c2);
592 else if (code2 == MINUS_EXPR)
593 /* NAME + CST1 > NAME - CST2 */
596 else if (code1 == MINUS_EXPR)
598 if (code2 == SSA_NAME)
599 /* NAME - CST < NAME */
601 else if (code2 == PLUS_EXPR)
602 /* NAME - CST1 < NAME + CST2 */
604 else if (code2 == MINUS_EXPR)
605 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
606 C1 and C2 are swapped in the call to compare_values. */
607 return compare_values (c2, c1);
613 /* We cannot compare non-constants. */
614 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
617 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
619 /* We cannot compare overflowed values. */
620 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
623 return tree_int_cst_compare (val1, val2);
629 /* First see if VAL1 and VAL2 are not the same. */
630 if (val1 == val2 || operand_equal_p (val1, val2, 0))
633 /* If VAL1 is a lower address than VAL2, return -1. */
634 if (operand_less_p (val1, val2) == 1)
637 /* If VAL1 is a higher address than VAL2, return +1. */
638 if (operand_less_p (val2, val1) == 1)
641 /* If VAL1 is different than VAL2, return +2.
642 For integer constants we either have already returned -1 or 1
643 or they are equivalent. We still might succeed in proving
644 something about non-trivial operands. */
645 if (TREE_CODE (val1) != INTEGER_CST
646 || TREE_CODE (val2) != INTEGER_CST)
648 t = fold_binary_to_constant (NE_EXPR, boolean_type_node, val1, val2);
649 if (t && tree_expr_nonzero_p (t))
658 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
659 0 if VAL is not inside VR,
660 -2 if we cannot tell either way.
662 FIXME, the current semantics of this functions are a bit quirky
663 when taken in the context of VRP. In here we do not care
664 about VR's type. If VR is the anti-range ~[3, 5] the call
665 value_inside_range (4, VR) will return 1.
667 This is counter-intuitive in a strict sense, but the callers
668 currently expect this. They are calling the function
669 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
670 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
673 This also applies to value_ranges_intersect_p and
674 range_includes_zero_p. The semantics of VR_RANGE and
675 VR_ANTI_RANGE should be encoded here, but that also means
676 adapting the users of these functions to the new semantics.
678 Benchmark compile/20001226-1.c compilation time after changing this
682 value_inside_range (tree val, value_range_t * vr)
686 cmp1 = operand_less_p (val, vr->min);
692 cmp2 = operand_less_p (vr->max, val);
700 /* Return true if value ranges VR0 and VR1 have a non-empty
703 Benchmark compile/20001226-1.c compilation time after changing this
708 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
710 /* The value ranges do not intersect if the maximum of the first range is
711 less than the minimum of the second range or vice versa.
712 When those relations are unknown, we can't do any better. */
713 if (operand_less_p (vr0->max, vr1->min) != 0)
715 if (operand_less_p (vr1->max, vr0->min) != 0)
721 /* Return true if VR includes the value zero, false otherwise. FIXME,
722 currently this will return false for an anti-range like ~[-4, 3].
723 This will be wrong when the semantics of value_inside_range are
724 modified (currently the users of this function expect these
728 range_includes_zero_p (value_range_t *vr)
732 gcc_assert (vr->type != VR_UNDEFINED
733 && vr->type != VR_VARYING
734 && !symbolic_range_p (vr));
736 zero = build_int_cst (TREE_TYPE (vr->min), 0);
737 return (value_inside_range (zero, vr) == 1);
740 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
741 false otherwise or if no value range information is available. */
744 ssa_name_nonnegative_p (tree t)
746 value_range_t *vr = get_value_range (t);
751 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
752 which would return a useful value should be encoded as a VR_RANGE. */
753 if (vr->type == VR_RANGE)
755 int result = compare_values (vr->min, integer_zero_node);
757 return (result == 0 || result == 1);
762 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
763 false otherwise or if no value range information is available. */
766 ssa_name_nonzero_p (tree t)
768 value_range_t *vr = get_value_range (t);
773 /* A VR_RANGE which does not include zero is a nonzero value. */
774 if (vr->type == VR_RANGE && !symbolic_range_p (vr))
775 return ! range_includes_zero_p (vr);
777 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
778 if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr))
779 return range_includes_zero_p (vr);
785 /* Extract value range information from an ASSERT_EXPR EXPR and store
789 extract_range_from_assert (value_range_t *vr_p, tree expr)
791 tree var, cond, limit, min, max, type;
792 value_range_t *var_vr, *limit_vr;
793 enum tree_code cond_code;
795 var = ASSERT_EXPR_VAR (expr);
796 cond = ASSERT_EXPR_COND (expr);
798 gcc_assert (COMPARISON_CLASS_P (cond));
800 /* Find VAR in the ASSERT_EXPR conditional. */
801 if (var == TREE_OPERAND (cond, 0))
803 /* If the predicate is of the form VAR COMP LIMIT, then we just
804 take LIMIT from the RHS and use the same comparison code. */
805 limit = TREE_OPERAND (cond, 1);
806 cond_code = TREE_CODE (cond);
810 /* If the predicate is of the form LIMIT COMP VAR, then we need
811 to flip around the comparison code to create the proper range
813 limit = TREE_OPERAND (cond, 0);
814 cond_code = swap_tree_comparison (TREE_CODE (cond));
817 type = TREE_TYPE (limit);
818 gcc_assert (limit != var);
820 /* For pointer arithmetic, we only keep track of pointer equality
822 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
824 set_value_range_to_varying (vr_p);
828 /* If LIMIT is another SSA name and LIMIT has a range of its own,
829 try to use LIMIT's range to avoid creating symbolic ranges
831 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
833 /* LIMIT's range is only interesting if it has any useful information. */
835 && (limit_vr->type == VR_UNDEFINED
836 || limit_vr->type == VR_VARYING
837 || symbolic_range_p (limit_vr)))
840 /* Initially, the new range has the same set of equivalences of
841 VAR's range. This will be revised before returning the final
842 value. Since assertions may be chained via mutually exclusive
843 predicates, we will need to trim the set of equivalences before
845 gcc_assert (vr_p->equiv == NULL);
846 vr_p->equiv = BITMAP_ALLOC (NULL);
847 add_equivalence (vr_p->equiv, var);
849 /* Extract a new range based on the asserted comparison for VAR and
850 LIMIT's value range. Notice that if LIMIT has an anti-range, we
851 will only use it for equality comparisons (EQ_EXPR). For any
852 other kind of assertion, we cannot derive a range from LIMIT's
853 anti-range that can be used to describe the new range. For
854 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
855 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
856 no single range for x_2 that could describe LE_EXPR, so we might
857 as well build the range [b_4, +INF] for it. */
858 if (cond_code == EQ_EXPR)
860 enum value_range_type range_type;
864 range_type = limit_vr->type;
870 range_type = VR_RANGE;
875 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
877 /* When asserting the equality VAR == LIMIT and LIMIT is another
878 SSA name, the new range will also inherit the equivalence set
880 if (TREE_CODE (limit) == SSA_NAME)
881 add_equivalence (vr_p->equiv, limit);
883 else if (cond_code == NE_EXPR)
885 /* As described above, when LIMIT's range is an anti-range and
886 this assertion is an inequality (NE_EXPR), then we cannot
887 derive anything from the anti-range. For instance, if
888 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
889 not imply that VAR's range is [0, 0]. So, in the case of
890 anti-ranges, we just assert the inequality using LIMIT and
893 If LIMIT_VR is a range, we can only use it to build a new
894 anti-range if LIMIT_VR is a single-valued range. For
895 instance, if LIMIT_VR is [0, 1], the predicate
896 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
897 Rather, it means that for value 0 VAR should be ~[0, 0]
898 and for value 1, VAR should be ~[1, 1]. We cannot
899 represent these ranges.
901 The only situation in which we can build a valid
902 anti-range is when LIMIT_VR is a single-valued range
903 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
904 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
906 && limit_vr->type == VR_RANGE
907 && compare_values (limit_vr->min, limit_vr->max) == 0)
914 /* In any other case, we cannot use LIMIT's range to build a
919 /* If MIN and MAX cover the whole range for their type, then
920 just use the original LIMIT. */
921 if (INTEGRAL_TYPE_P (type)
922 && min == TYPE_MIN_VALUE (type)
923 && max == TYPE_MAX_VALUE (type))
926 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
928 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
930 min = TYPE_MIN_VALUE (type);
932 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
936 /* If LIMIT_VR is of the form [N1, N2], we need to build the
937 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
942 /* If the maximum value forces us to be out of bounds, simply punt.
943 It would be pointless to try and do anything more since this
944 all should be optimized away above us. */
945 if (cond_code == LT_EXPR && compare_values (max, min) == 0)
946 set_value_range_to_varying (vr_p);
949 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
950 if (cond_code == LT_EXPR)
952 tree one = build_int_cst (type, 1);
953 max = fold_build2 (MINUS_EXPR, type, max, one);
956 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
959 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
961 max = TYPE_MAX_VALUE (type);
963 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
967 /* If LIMIT_VR is of the form [N1, N2], we need to build the
968 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
973 /* If the minimum value forces us to be out of bounds, simply punt.
974 It would be pointless to try and do anything more since this
975 all should be optimized away above us. */
976 if (cond_code == GT_EXPR && compare_values (min, max) == 0)
977 set_value_range_to_varying (vr_p);
980 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
981 if (cond_code == GT_EXPR)
983 tree one = build_int_cst (type, 1);
984 min = fold_build2 (PLUS_EXPR, type, min, one);
987 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
993 /* If VAR already had a known range, it may happen that the new
994 range we have computed and VAR's range are not compatible. For
998 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
1000 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
1002 While the above comes from a faulty program, it will cause an ICE
1003 later because p_8 and p_6 will have incompatible ranges and at
1004 the same time will be considered equivalent. A similar situation
1008 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
1010 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
1012 Again i_6 and i_7 will have incompatible ranges. It would be
1013 pointless to try and do anything with i_7's range because
1014 anything dominated by 'if (i_5 < 5)' will be optimized away.
1015 Note, due to the wa in which simulation proceeds, the statement
1016 i_7 = ASSERT_EXPR <...> we would never be visited because the
1017 conditional 'if (i_5 < 5)' always evaluates to false. However,
1018 this extra check does not hurt and may protect against future
1019 changes to VRP that may get into a situation similar to the
1020 NULL pointer dereference example.
1022 Note that these compatibility tests are only needed when dealing
1023 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1024 are both anti-ranges, they will always be compatible, because two
1025 anti-ranges will always have a non-empty intersection. */
1027 var_vr = get_value_range (var);
1029 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1030 ranges or anti-ranges. */
1031 if (vr_p->type == VR_VARYING
1032 || vr_p->type == VR_UNDEFINED
1033 || var_vr->type == VR_VARYING
1034 || var_vr->type == VR_UNDEFINED
1035 || symbolic_range_p (vr_p)
1036 || symbolic_range_p (var_vr))
1039 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
1041 /* If the two ranges have a non-empty intersection, we can
1042 refine the resulting range. Since the assert expression
1043 creates an equivalency and at the same time it asserts a
1044 predicate, we can take the intersection of the two ranges to
1045 get better precision. */
1046 if (value_ranges_intersect_p (var_vr, vr_p))
1048 /* Use the larger of the two minimums. */
1049 if (compare_values (vr_p->min, var_vr->min) == -1)
1054 /* Use the smaller of the two maximums. */
1055 if (compare_values (vr_p->max, var_vr->max) == 1)
1060 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
1064 /* The two ranges do not intersect, set the new range to
1065 VARYING, because we will not be able to do anything
1066 meaningful with it. */
1067 set_value_range_to_varying (vr_p);
1070 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
1071 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
1073 /* A range and an anti-range will cancel each other only if
1074 their ends are the same. For instance, in the example above,
1075 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1076 so VR_P should be set to VR_VARYING. */
1077 if (compare_values (var_vr->min, vr_p->min) == 0
1078 && compare_values (var_vr->max, vr_p->max) == 0)
1079 set_value_range_to_varying (vr_p);
1082 tree min, max, anti_min, anti_max, real_min, real_max;
1085 /* We want to compute the logical AND of the two ranges;
1086 there are three cases to consider.
1089 1. The VR_ANTI_RANGE range is completely within the
1090 VR_RANGE and the endpoints of the ranges are
1091 different. In that case the resulting range
1092 should be whichever range is more precise.
1093 Typically that will be the VR_RANGE.
1095 2. The VR_ANTI_RANGE is completely disjoint from
1096 the VR_RANGE. In this case the resulting range
1097 should be the VR_RANGE.
1099 3. There is some overlap between the VR_ANTI_RANGE
1102 3a. If the high limit of the VR_ANTI_RANGE resides
1103 within the VR_RANGE, then the result is a new
1104 VR_RANGE starting at the high limit of the
1105 the VR_ANTI_RANGE + 1 and extending to the
1106 high limit of the original VR_RANGE.
1108 3b. If the low limit of the VR_ANTI_RANGE resides
1109 within the VR_RANGE, then the result is a new
1110 VR_RANGE starting at the low limit of the original
1111 VR_RANGE and extending to the low limit of the
1112 VR_ANTI_RANGE - 1. */
1113 if (vr_p->type == VR_ANTI_RANGE)
1115 anti_min = vr_p->min;
1116 anti_max = vr_p->max;
1117 real_min = var_vr->min;
1118 real_max = var_vr->max;
1122 anti_min = var_vr->min;
1123 anti_max = var_vr->max;
1124 real_min = vr_p->min;
1125 real_max = vr_p->max;
1129 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1130 not including any endpoints. */
1131 if (compare_values (anti_max, real_max) == -1
1132 && compare_values (anti_min, real_min) == 1)
1134 set_value_range (vr_p, VR_RANGE, real_min,
1135 real_max, vr_p->equiv);
1137 /* Case 2, VR_ANTI_RANGE completely disjoint from
1139 else if (compare_values (anti_min, real_max) == 1
1140 || compare_values (anti_max, real_min) == -1)
1142 set_value_range (vr_p, VR_RANGE, real_min,
1143 real_max, vr_p->equiv);
1145 /* Case 3a, the anti-range extends into the low
1146 part of the real range. Thus creating a new
1147 low for the real range. */
1148 else if (((cmp = compare_values (anti_max, real_min)) == 1
1150 && compare_values (anti_max, real_max) == -1)
1152 min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min),
1154 build_int_cst (TREE_TYPE (var_vr->min), 1));
1156 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1158 /* Case 3b, the anti-range extends into the high
1159 part of the real range. Thus creating a new
1160 higher for the real range. */
1161 else if (compare_values (anti_min, real_min) == 1
1162 && ((cmp = compare_values (anti_min, real_max)) == -1
1165 max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min),
1167 build_int_cst (TREE_TYPE (var_vr->min), 1));
1169 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1176 /* Extract range information from SSA name VAR and store it in VR. If
1177 VAR has an interesting range, use it. Otherwise, create the
1178 range [VAR, VAR] and return it. This is useful in situations where
1179 we may have conditionals testing values of VARYING names. For
1186 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1190 extract_range_from_ssa_name (value_range_t *vr, tree var)
1192 value_range_t *var_vr = get_value_range (var);
1194 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
1195 copy_value_range (vr, var_vr);
1197 set_value_range (vr, VR_RANGE, var, var, NULL);
1199 add_equivalence (vr->equiv, var);
1203 /* Wrapper around int_const_binop. If the operation overflows and we
1204 are not using wrapping arithmetic, then adjust the result to be
1205 -INF or +INF depending on CODE, VAL1 and VAL2. */
1208 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
1212 res = int_const_binop (code, val1, val2, 0);
1214 /* If we are not using wrapping arithmetic, operate symbolically
1215 on -INF and +INF. */
1216 if (TYPE_UNSIGNED (TREE_TYPE (val1))
1219 int checkz = compare_values (res, val1);
1220 bool overflow = false;
1222 /* Ensure that res = val1 [+*] val2 >= val1
1223 or that res = val1 - val2 <= val1. */
1224 if ((code == PLUS_EXPR
1225 && !(checkz == 1 || checkz == 0))
1226 || (code == MINUS_EXPR
1227 && !(checkz == 0 || checkz == -1)))
1231 /* Checking for multiplication overflow is done by dividing the
1232 output of the multiplication by the first input of the
1233 multiplication. If the result of that division operation is
1234 not equal to the second input of the multiplication, then the
1235 multiplication overflowed. */
1236 else if (code == MULT_EXPR && !integer_zerop (val1))
1238 tree tmp = int_const_binop (TRUNC_DIV_EXPR,
1241 int check = compare_values (tmp, val2);
1249 res = copy_node (res);
1250 TREE_OVERFLOW (res) = 1;
1254 else if (TREE_OVERFLOW (res)
1255 && !TREE_OVERFLOW (val1)
1256 && !TREE_OVERFLOW (val2))
1258 /* If the operation overflowed but neither VAL1 nor VAL2 are
1259 overflown, return -INF or +INF depending on the operation
1260 and the combination of signs of the operands. */
1261 int sgn1 = tree_int_cst_sgn (val1);
1262 int sgn2 = tree_int_cst_sgn (val2);
1264 /* Notice that we only need to handle the restricted set of
1265 operations handled by extract_range_from_binary_expr.
1266 Among them, only multiplication, addition and subtraction
1267 can yield overflow without overflown operands because we
1268 are working with integral types only... except in the
1269 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1270 for division too. */
1272 /* For multiplication, the sign of the overflow is given
1273 by the comparison of the signs of the operands. */
1274 if ((code == MULT_EXPR && sgn1 == sgn2)
1275 /* For addition, the operands must be of the same sign
1276 to yield an overflow. Its sign is therefore that
1277 of one of the operands, for example the first. */
1278 || (code == PLUS_EXPR && sgn1 > 0)
1279 /* For subtraction, the operands must be of different
1280 signs to yield an overflow. Its sign is therefore
1281 that of the first operand or the opposite of that
1282 of the second operand. A first operand of 0 counts
1283 as positive here, for the corner case 0 - (-INF),
1284 which overflows, but must yield +INF. */
1285 || (code == MINUS_EXPR && sgn1 >= 0)
1286 /* For division, the only case is -INF / -1 = +INF. */
1287 || code == TRUNC_DIV_EXPR
1288 || code == FLOOR_DIV_EXPR
1289 || code == CEIL_DIV_EXPR
1290 || code == EXACT_DIV_EXPR
1291 || code == ROUND_DIV_EXPR)
1292 return TYPE_MAX_VALUE (TREE_TYPE (res));
1294 return TYPE_MIN_VALUE (TREE_TYPE (res));
1301 /* Extract range information from a binary expression EXPR based on
1302 the ranges of each of its operands and the expression code. */
1305 extract_range_from_binary_expr (value_range_t *vr, tree expr)
1307 enum tree_code code = TREE_CODE (expr);
1308 enum value_range_type type;
1309 tree op0, op1, min, max;
1311 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1312 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1314 /* Not all binary expressions can be applied to ranges in a
1315 meaningful way. Handle only arithmetic operations. */
1316 if (code != PLUS_EXPR
1317 && code != MINUS_EXPR
1318 && code != MULT_EXPR
1319 && code != TRUNC_DIV_EXPR
1320 && code != FLOOR_DIV_EXPR
1321 && code != CEIL_DIV_EXPR
1322 && code != EXACT_DIV_EXPR
1323 && code != ROUND_DIV_EXPR
1326 && code != BIT_AND_EXPR
1327 && code != TRUTH_ANDIF_EXPR
1328 && code != TRUTH_ORIF_EXPR
1329 && code != TRUTH_AND_EXPR
1330 && code != TRUTH_OR_EXPR)
1332 set_value_range_to_varying (vr);
1336 /* Get value ranges for each operand. For constant operands, create
1337 a new value range with the operand to simplify processing. */
1338 op0 = TREE_OPERAND (expr, 0);
1339 if (TREE_CODE (op0) == SSA_NAME)
1340 vr0 = *(get_value_range (op0));
1341 else if (is_gimple_min_invariant (op0))
1342 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1344 set_value_range_to_varying (&vr0);
1346 op1 = TREE_OPERAND (expr, 1);
1347 if (TREE_CODE (op1) == SSA_NAME)
1348 vr1 = *(get_value_range (op1));
1349 else if (is_gimple_min_invariant (op1))
1350 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1352 set_value_range_to_varying (&vr1);
1354 /* If either range is UNDEFINED, so is the result. */
1355 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1357 set_value_range_to_undefined (vr);
1361 /* The type of the resulting value range defaults to VR0.TYPE. */
1364 /* Refuse to operate on VARYING ranges, ranges of different kinds
1365 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1366 because we may be able to derive a useful range even if one of
1367 the operands is VR_VARYING or symbolic range. TODO, we may be
1368 able to derive anti-ranges in some cases. */
1369 if (code != BIT_AND_EXPR
1370 && code != TRUTH_AND_EXPR
1371 && code != TRUTH_OR_EXPR
1372 && (vr0.type == VR_VARYING
1373 || vr1.type == VR_VARYING
1374 || vr0.type != vr1.type
1375 || symbolic_range_p (&vr0)
1376 || symbolic_range_p (&vr1)))
1378 set_value_range_to_varying (vr);
1382 /* Now evaluate the expression to determine the new range. */
1383 if (POINTER_TYPE_P (TREE_TYPE (expr))
1384 || POINTER_TYPE_P (TREE_TYPE (op0))
1385 || POINTER_TYPE_P (TREE_TYPE (op1)))
1387 /* For pointer types, we are really only interested in asserting
1388 whether the expression evaluates to non-NULL. FIXME, we used
1389 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1390 ivopts is generating expressions with pointer multiplication
1392 if (code == PLUS_EXPR)
1394 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1395 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1396 else if (range_is_null (&vr0) && range_is_null (&vr1))
1397 set_value_range_to_null (vr, TREE_TYPE (expr));
1399 set_value_range_to_varying (vr);
1403 /* Subtracting from a pointer, may yield 0, so just drop the
1404 resulting range to varying. */
1405 set_value_range_to_varying (vr);
1411 /* For integer ranges, apply the operation to each end of the
1412 range and see what we end up with. */
1413 if (code == TRUTH_ANDIF_EXPR
1414 || code == TRUTH_ORIF_EXPR
1415 || code == TRUTH_AND_EXPR
1416 || code == TRUTH_OR_EXPR)
1418 /* If one of the operands is zero, we know that the whole
1419 expression evaluates zero. */
1420 if (code == TRUTH_AND_EXPR
1421 && ((vr0.type == VR_RANGE
1422 && integer_zerop (vr0.min)
1423 && integer_zerop (vr0.max))
1424 || (vr1.type == VR_RANGE
1425 && integer_zerop (vr1.min)
1426 && integer_zerop (vr1.max))))
1429 min = max = build_int_cst (TREE_TYPE (expr), 0);
1431 /* If one of the operands is one, we know that the whole
1432 expression evaluates one. */
1433 else if (code == TRUTH_OR_EXPR
1434 && ((vr0.type == VR_RANGE
1435 && integer_onep (vr0.min)
1436 && integer_onep (vr0.max))
1437 || (vr1.type == VR_RANGE
1438 && integer_onep (vr1.min)
1439 && integer_onep (vr1.max))))
1442 min = max = build_int_cst (TREE_TYPE (expr), 1);
1444 else if (vr0.type != VR_VARYING
1445 && vr1.type != VR_VARYING
1446 && vr0.type == vr1.type
1447 && !symbolic_range_p (&vr0)
1448 && !symbolic_range_p (&vr1))
1450 /* Boolean expressions cannot be folded with int_const_binop. */
1451 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1452 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1456 /* The result of a TRUTH_*_EXPR is always true or false. */
1457 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
1461 else if (code == PLUS_EXPR
1463 || code == MAX_EXPR)
1465 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1466 VR_VARYING. It would take more effort to compute a precise
1467 range for such a case. For example, if we have op0 == 1 and
1468 op1 == -1 with their ranges both being ~[0,0], we would have
1469 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1470 Note that we are guaranteed to have vr0.type == vr1.type at
1472 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1474 set_value_range_to_varying (vr);
1478 /* For operations that make the resulting range directly
1479 proportional to the original ranges, apply the operation to
1480 the same end of each range. */
1481 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1482 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1484 else if (code == MULT_EXPR
1485 || code == TRUNC_DIV_EXPR
1486 || code == FLOOR_DIV_EXPR
1487 || code == CEIL_DIV_EXPR
1488 || code == EXACT_DIV_EXPR
1489 || code == ROUND_DIV_EXPR)
1494 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1495 drop to VR_VARYING. It would take more effort to compute a
1496 precise range for such a case. For example, if we have
1497 op0 == 65536 and op1 == 65536 with their ranges both being
1498 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1499 we cannot claim that the product is in ~[0,0]. Note that we
1500 are guaranteed to have vr0.type == vr1.type at this
1502 if (code == MULT_EXPR
1503 && vr0.type == VR_ANTI_RANGE
1504 && (flag_wrapv || TYPE_UNSIGNED (TREE_TYPE (op0))))
1506 set_value_range_to_varying (vr);
1510 /* Multiplications and divisions are a bit tricky to handle,
1511 depending on the mix of signs we have in the two ranges, we
1512 need to operate on different values to get the minimum and
1513 maximum values for the new range. One approach is to figure
1514 out all the variations of range combinations and do the
1517 However, this involves several calls to compare_values and it
1518 is pretty convoluted. It's simpler to do the 4 operations
1519 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1520 MAX1) and then figure the smallest and largest values to form
1523 /* Divisions by zero result in a VARYING value. */
1524 if (code != MULT_EXPR
1525 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1527 set_value_range_to_varying (vr);
1531 /* Compute the 4 cross operations. */
1532 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1534 val[1] = (vr1.max != vr1.min)
1535 ? vrp_int_const_binop (code, vr0.min, vr1.max)
1538 val[2] = (vr0.max != vr0.min)
1539 ? vrp_int_const_binop (code, vr0.max, vr1.min)
1542 val[3] = (vr0.min != vr0.max && vr1.min != vr1.max)
1543 ? vrp_int_const_binop (code, vr0.max, vr1.max)
1546 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1550 for (i = 1; i < 4; i++)
1552 if (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
1553 || !is_gimple_min_invariant (max) || TREE_OVERFLOW (max))
1558 if (!is_gimple_min_invariant (val[i]) || TREE_OVERFLOW (val[i]))
1560 /* If we found an overflowed value, set MIN and MAX
1561 to it so that we set the resulting range to
1567 if (compare_values (val[i], min) == -1)
1570 if (compare_values (val[i], max) == 1)
1575 else if (code == MINUS_EXPR)
1577 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1578 VR_VARYING. It would take more effort to compute a precise
1579 range for such a case. For example, if we have op0 == 1 and
1580 op1 == 1 with their ranges both being ~[0,0], we would have
1581 op0 - op1 == 0, so we cannot claim that the difference is in
1582 ~[0,0]. Note that we are guaranteed to have
1583 vr0.type == vr1.type at this point. */
1584 if (vr0.type == VR_ANTI_RANGE)
1586 set_value_range_to_varying (vr);
1590 /* For MINUS_EXPR, apply the operation to the opposite ends of
1592 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1593 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1595 else if (code == BIT_AND_EXPR)
1597 if (vr0.type == VR_RANGE
1598 && vr0.min == vr0.max
1599 && tree_expr_nonnegative_p (vr0.max)
1600 && TREE_CODE (vr0.max) == INTEGER_CST)
1602 min = build_int_cst (TREE_TYPE (expr), 0);
1605 else if (vr1.type == VR_RANGE
1606 && vr1.min == vr1.max
1607 && tree_expr_nonnegative_p (vr1.max)
1608 && TREE_CODE (vr1.max) == INTEGER_CST)
1611 min = build_int_cst (TREE_TYPE (expr), 0);
1616 set_value_range_to_varying (vr);
1623 /* If either MIN or MAX overflowed, then set the resulting range to
1625 if (!is_gimple_min_invariant (min) || TREE_OVERFLOW (min)
1626 || !is_gimple_min_invariant (max) || TREE_OVERFLOW (max))
1628 set_value_range_to_varying (vr);
1632 cmp = compare_values (min, max);
1633 if (cmp == -2 || cmp == 1)
1635 /* If the new range has its limits swapped around (MIN > MAX),
1636 then the operation caused one of them to wrap around, mark
1637 the new range VARYING. */
1638 set_value_range_to_varying (vr);
1641 set_value_range (vr, type, min, max, NULL);
1645 /* Extract range information from a unary expression EXPR based on
1646 the range of its operand and the expression code. */
1649 extract_range_from_unary_expr (value_range_t *vr, tree expr)
1651 enum tree_code code = TREE_CODE (expr);
1654 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1656 /* Refuse to operate on certain unary expressions for which we
1657 cannot easily determine a resulting range. */
1658 if (code == FIX_TRUNC_EXPR
1659 || code == FLOAT_EXPR
1660 || code == BIT_NOT_EXPR
1661 || code == NON_LVALUE_EXPR
1662 || code == CONJ_EXPR)
1664 set_value_range_to_varying (vr);
1668 /* Get value ranges for the operand. For constant operands, create
1669 a new value range with the operand to simplify processing. */
1670 op0 = TREE_OPERAND (expr, 0);
1671 if (TREE_CODE (op0) == SSA_NAME)
1672 vr0 = *(get_value_range (op0));
1673 else if (is_gimple_min_invariant (op0))
1674 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1676 set_value_range_to_varying (&vr0);
1678 /* If VR0 is UNDEFINED, so is the result. */
1679 if (vr0.type == VR_UNDEFINED)
1681 set_value_range_to_undefined (vr);
1685 /* Refuse to operate on symbolic ranges, or if neither operand is
1686 a pointer or integral type. */
1687 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0))
1688 && !POINTER_TYPE_P (TREE_TYPE (op0)))
1689 || (vr0.type != VR_VARYING
1690 && symbolic_range_p (&vr0)))
1692 set_value_range_to_varying (vr);
1696 /* If the expression involves pointers, we are only interested in
1697 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1698 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
1700 if (range_is_nonnull (&vr0) || tree_expr_nonzero_p (expr))
1701 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1702 else if (range_is_null (&vr0))
1703 set_value_range_to_null (vr, TREE_TYPE (expr));
1705 set_value_range_to_varying (vr);
1710 /* Handle unary expressions on integer ranges. */
1711 if (code == NOP_EXPR || code == CONVERT_EXPR)
1713 tree inner_type = TREE_TYPE (op0);
1714 tree outer_type = TREE_TYPE (expr);
1716 /* If VR0 represents a simple range, then try to convert
1717 the min and max values for the range to the same type
1718 as OUTER_TYPE. If the results compare equal to VR0's
1719 min and max values and the new min is still less than
1720 or equal to the new max, then we can safely use the newly
1721 computed range for EXPR. This allows us to compute
1722 accurate ranges through many casts. */
1723 if (vr0.type == VR_RANGE
1724 || (vr0.type == VR_VARYING
1725 && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type)))
1727 tree new_min, new_max, orig_min, orig_max;
1729 /* Convert the input operand min/max to OUTER_TYPE. If
1730 the input has no range information, then use the min/max
1731 for the input's type. */
1732 if (vr0.type == VR_RANGE)
1739 orig_min = TYPE_MIN_VALUE (inner_type);
1740 orig_max = TYPE_MAX_VALUE (inner_type);
1743 new_min = fold_convert (outer_type, orig_min);
1744 new_max = fold_convert (outer_type, orig_max);
1746 /* Verify the new min/max values are gimple values and
1747 that they compare equal to the original input's
1749 if (is_gimple_val (new_min)
1750 && is_gimple_val (new_max)
1751 && tree_int_cst_equal (new_min, orig_min)
1752 && tree_int_cst_equal (new_max, orig_max)
1753 && (cmp = compare_values (new_min, new_max)) <= 0
1756 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
1761 /* When converting types of different sizes, set the result to
1762 VARYING. Things like sign extensions and precision loss may
1763 change the range. For instance, if x_3 is of type 'long long
1764 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1765 is impossible to know at compile time whether y_5 will be
1767 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
1768 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
1770 set_value_range_to_varying (vr);
1775 /* Conversion of a VR_VARYING value to a wider type can result
1776 in a usable range. So wait until after we've handled conversions
1777 before dropping the result to VR_VARYING if we had a source
1778 operand that is VR_VARYING. */
1779 if (vr0.type == VR_VARYING)
1781 set_value_range_to_varying (vr);
1785 /* Apply the operation to each end of the range and see what we end
1787 if (code == NEGATE_EXPR
1788 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1790 /* NEGATE_EXPR flips the range around. We need to treat
1791 TYPE_MIN_VALUE specially dependent on wrapping, range type
1792 and if it was used as minimum or maximum value:
1793 -~[MIN, MIN] == ~[MIN, MIN]
1794 -[MIN, 0] == [0, MAX] for -fno-wrapv
1795 -[MIN, 0] == [0, MIN] for -fwrapv (will be set to varying later) */
1796 min = vr0.max == TYPE_MIN_VALUE (TREE_TYPE (expr))
1797 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1798 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1800 max = vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr))
1801 ? (vr0.type == VR_ANTI_RANGE || flag_wrapv
1802 ? TYPE_MIN_VALUE (TREE_TYPE (expr))
1803 : TYPE_MAX_VALUE (TREE_TYPE (expr)))
1804 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1807 else if (code == NEGATE_EXPR
1808 && TYPE_UNSIGNED (TREE_TYPE (expr)))
1810 if (!range_includes_zero_p (&vr0))
1812 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1813 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1817 if (range_is_null (&vr0))
1818 set_value_range_to_null (vr, TREE_TYPE (expr));
1820 set_value_range_to_varying (vr);
1824 else if (code == ABS_EXPR
1825 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
1827 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1830 && ((vr0.type == VR_RANGE
1831 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1832 || (vr0.type == VR_ANTI_RANGE
1833 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
1834 && !range_includes_zero_p (&vr0))))
1836 set_value_range_to_varying (vr);
1840 /* ABS_EXPR may flip the range around, if the original range
1841 included negative values. */
1842 min = (vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
1843 ? TYPE_MAX_VALUE (TREE_TYPE (expr))
1844 : fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1846 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1848 cmp = compare_values (min, max);
1850 /* If a VR_ANTI_RANGEs contains zero, then we have
1851 ~[-INF, min(MIN, MAX)]. */
1852 if (vr0.type == VR_ANTI_RANGE)
1854 if (range_includes_zero_p (&vr0))
1856 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
1858 /* Take the lower of the two values. */
1862 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1863 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1864 flag_wrapv is set and the original anti-range doesn't include
1865 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1866 min = (flag_wrapv && vr0.min != type_min_value
1867 ? int_const_binop (PLUS_EXPR,
1869 integer_one_node, 0)
1874 /* All else has failed, so create the range [0, INF], even for
1875 flag_wrapv since TYPE_MIN_VALUE is in the original
1877 vr0.type = VR_RANGE;
1878 min = build_int_cst (TREE_TYPE (expr), 0);
1879 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
1883 /* If the range contains zero then we know that the minimum value in the
1884 range will be zero. */
1885 else if (range_includes_zero_p (&vr0))
1889 min = build_int_cst (TREE_TYPE (expr), 0);
1893 /* If the range was reversed, swap MIN and MAX. */
1904 /* Otherwise, operate on each end of the range. */
1905 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
1906 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
1909 cmp = compare_values (min, max);
1910 if (cmp == -2 || cmp == 1)
1912 /* If the new range has its limits swapped around (MIN > MAX),
1913 then the operation caused one of them to wrap around, mark
1914 the new range VARYING. */
1915 set_value_range_to_varying (vr);
1918 set_value_range (vr, vr0.type, min, max, NULL);
1922 /* Extract range information from a comparison expression EXPR based
1923 on the range of its operand and the expression code. */
1926 extract_range_from_comparison (value_range_t *vr, tree expr)
1928 tree val = vrp_evaluate_conditional (expr, false);
1931 /* Since this expression was found on the RHS of an assignment,
1932 its type may be different from _Bool. Convert VAL to EXPR's
1934 val = fold_convert (TREE_TYPE (expr), val);
1935 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
1938 /* The result of a comparison is always true or false. */
1939 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
1943 /* Try to compute a useful range out of expression EXPR and store it
1947 extract_range_from_expr (value_range_t *vr, tree expr)
1949 enum tree_code code = TREE_CODE (expr);
1951 if (code == ASSERT_EXPR)
1952 extract_range_from_assert (vr, expr);
1953 else if (code == SSA_NAME)
1954 extract_range_from_ssa_name (vr, expr);
1955 else if (TREE_CODE_CLASS (code) == tcc_binary
1956 || code == TRUTH_ANDIF_EXPR
1957 || code == TRUTH_ORIF_EXPR
1958 || code == TRUTH_AND_EXPR
1959 || code == TRUTH_OR_EXPR
1960 || code == TRUTH_XOR_EXPR)
1961 extract_range_from_binary_expr (vr, expr);
1962 else if (TREE_CODE_CLASS (code) == tcc_unary)
1963 extract_range_from_unary_expr (vr, expr);
1964 else if (TREE_CODE_CLASS (code) == tcc_comparison)
1965 extract_range_from_comparison (vr, expr);
1966 else if (is_gimple_min_invariant (expr))
1967 set_value_range (vr, VR_RANGE, expr, expr, NULL);
1969 set_value_range_to_varying (vr);
1971 /* If we got a varying range from the tests above, try a final
1972 time to derive a nonnegative or nonzero range. This time
1973 relying primarily on generic routines in fold in conjunction
1975 if (vr->type == VR_VARYING)
1977 if (INTEGRAL_TYPE_P (TREE_TYPE (expr))
1978 && vrp_expr_computes_nonnegative (expr))
1979 set_value_range_to_nonnegative (vr, TREE_TYPE (expr));
1980 else if (vrp_expr_computes_nonzero (expr))
1981 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1985 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1986 would be profitable to adjust VR using scalar evolution information
1987 for VAR. If so, update VR with the new limits. */
1990 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
1993 tree init, step, chrec, tmin, tmax, min, max, type;
1994 enum ev_direction dir;
1996 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1997 better opportunities than a regular range, but I'm not sure. */
1998 if (vr->type == VR_ANTI_RANGE)
2001 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
2002 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
2005 init = initial_condition_in_loop_num (chrec, loop->num);
2006 step = evolution_part_in_loop_num (chrec, loop->num);
2008 /* If STEP is symbolic, we can't know whether INIT will be the
2009 minimum or maximum value in the range. Also, unless INIT is
2010 a simple expression, compare_values and possibly other functions
2011 in tree-vrp won't be able to handle it. */
2012 if (step == NULL_TREE
2013 || !is_gimple_min_invariant (step)
2014 || !valid_value_p (init))
2017 dir = scev_direction (chrec);
2018 if (/* Do not adjust ranges if we do not know whether the iv increases
2019 or decreases, ... */
2020 dir == EV_DIR_UNKNOWN
2021 /* ... or if it may wrap. */
2022 || scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec),
2026 type = TREE_TYPE (var);
2027 if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type))
2028 tmin = lower_bound_in_type (type, type);
2030 tmin = TYPE_MIN_VALUE (type);
2031 if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type))
2032 tmax = upper_bound_in_type (type, type);
2034 tmax = TYPE_MAX_VALUE (type);
2036 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2041 /* For VARYING or UNDEFINED ranges, just about anything we get
2042 from scalar evolutions should be better. */
2044 if (dir == EV_DIR_DECREASES)
2049 /* If we would create an invalid range, then just assume we
2050 know absolutely nothing. This may be over-conservative,
2051 but it's clearly safe, and should happen only in unreachable
2052 parts of code, or for invalid programs. */
2053 if (compare_values (min, max) == 1)
2056 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2058 else if (vr->type == VR_RANGE)
2063 if (dir == EV_DIR_DECREASES)
2065 /* INIT is the maximum value. If INIT is lower than VR->MAX
2066 but no smaller than VR->MIN, set VR->MAX to INIT. */
2067 if (compare_values (init, max) == -1)
2071 /* If we just created an invalid range with the minimum
2072 greater than the maximum, we fail conservatively.
2073 This should happen only in unreachable
2074 parts of code, or for invalid programs. */
2075 if (compare_values (min, max) == 1)
2081 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2082 if (compare_values (init, min) == 1)
2086 /* Again, avoid creating invalid range by failing. */
2087 if (compare_values (min, max) == 1)
2092 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2097 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2099 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2100 all the values in the ranges.
2102 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2104 - Return NULL_TREE if it is not always possible to determine the
2105 value of the comparison. */
2109 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1)
2111 /* VARYING or UNDEFINED ranges cannot be compared. */
2112 if (vr0->type == VR_VARYING
2113 || vr0->type == VR_UNDEFINED
2114 || vr1->type == VR_VARYING
2115 || vr1->type == VR_UNDEFINED)
2118 /* Anti-ranges need to be handled separately. */
2119 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
2121 /* If both are anti-ranges, then we cannot compute any
2123 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
2126 /* These comparisons are never statically computable. */
2133 /* Equality can be computed only between a range and an
2134 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2135 if (vr0->type == VR_RANGE)
2137 /* To simplify processing, make VR0 the anti-range. */
2138 value_range_t *tmp = vr0;
2143 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
2145 if (compare_values (vr0->min, vr1->min) == 0
2146 && compare_values (vr0->max, vr1->max) == 0)
2147 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2152 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2153 operands around and change the comparison code. */
2154 if (comp == GT_EXPR || comp == GE_EXPR)
2157 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
2163 if (comp == EQ_EXPR)
2165 /* Equality may only be computed if both ranges represent
2166 exactly one value. */
2167 if (compare_values (vr0->min, vr0->max) == 0
2168 && compare_values (vr1->min, vr1->max) == 0)
2170 int cmp_min = compare_values (vr0->min, vr1->min);
2171 int cmp_max = compare_values (vr0->max, vr1->max);
2172 if (cmp_min == 0 && cmp_max == 0)
2173 return boolean_true_node;
2174 else if (cmp_min != -2 && cmp_max != -2)
2175 return boolean_false_node;
2177 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2178 else if (compare_values (vr0->min, vr1->max) == 1
2179 || compare_values (vr1->min, vr0->max) == 1)
2180 return boolean_false_node;
2184 else if (comp == NE_EXPR)
2188 /* If VR0 is completely to the left or completely to the right
2189 of VR1, they are always different. Notice that we need to
2190 make sure that both comparisons yield similar results to
2191 avoid comparing values that cannot be compared at
2193 cmp1 = compare_values (vr0->max, vr1->min);
2194 cmp2 = compare_values (vr0->min, vr1->max);
2195 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
2196 return boolean_true_node;
2198 /* If VR0 and VR1 represent a single value and are identical,
2200 else if (compare_values (vr0->min, vr0->max) == 0
2201 && compare_values (vr1->min, vr1->max) == 0
2202 && compare_values (vr0->min, vr1->min) == 0
2203 && compare_values (vr0->max, vr1->max) == 0)
2204 return boolean_false_node;
2206 /* Otherwise, they may or may not be different. */
2210 else if (comp == LT_EXPR || comp == LE_EXPR)
2214 /* If VR0 is to the left of VR1, return true. */
2215 tst = compare_values (vr0->max, vr1->min);
2216 if ((comp == LT_EXPR && tst == -1)
2217 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2218 return boolean_true_node;
2220 /* If VR0 is to the right of VR1, return false. */
2221 tst = compare_values (vr0->min, vr1->max);
2222 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2223 || (comp == LE_EXPR && tst == 1))
2224 return boolean_false_node;
2226 /* Otherwise, we don't know. */
2234 /* Given a value range VR, a value VAL and a comparison code COMP, return
2235 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2236 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2237 always returns false. Return NULL_TREE if it is not always
2238 possible to determine the value of the comparison. */
2241 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val)
2243 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2246 /* Anti-ranges need to be handled separately. */
2247 if (vr->type == VR_ANTI_RANGE)
2249 /* For anti-ranges, the only predicates that we can compute at
2250 compile time are equality and inequality. */
2257 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2258 if (value_inside_range (val, vr) == 1)
2259 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2264 if (comp == EQ_EXPR)
2266 /* EQ_EXPR may only be computed if VR represents exactly
2268 if (compare_values (vr->min, vr->max) == 0)
2270 int cmp = compare_values (vr->min, val);
2272 return boolean_true_node;
2273 else if (cmp == -1 || cmp == 1 || cmp == 2)
2274 return boolean_false_node;
2276 else if (compare_values (val, vr->min) == -1
2277 || compare_values (vr->max, val) == -1)
2278 return boolean_false_node;
2282 else if (comp == NE_EXPR)
2284 /* If VAL is not inside VR, then they are always different. */
2285 if (compare_values (vr->max, val) == -1
2286 || compare_values (vr->min, val) == 1)
2287 return boolean_true_node;
2289 /* If VR represents exactly one value equal to VAL, then return
2291 if (compare_values (vr->min, vr->max) == 0
2292 && compare_values (vr->min, val) == 0)
2293 return boolean_false_node;
2295 /* Otherwise, they may or may not be different. */
2298 else if (comp == LT_EXPR || comp == LE_EXPR)
2302 /* If VR is to the left of VAL, return true. */
2303 tst = compare_values (vr->max, val);
2304 if ((comp == LT_EXPR && tst == -1)
2305 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2306 return boolean_true_node;
2308 /* If VR is to the right of VAL, return false. */
2309 tst = compare_values (vr->min, val);
2310 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2311 || (comp == LE_EXPR && tst == 1))
2312 return boolean_false_node;
2314 /* Otherwise, we don't know. */
2317 else if (comp == GT_EXPR || comp == GE_EXPR)
2321 /* If VR is to the right of VAL, return true. */
2322 tst = compare_values (vr->min, val);
2323 if ((comp == GT_EXPR && tst == 1)
2324 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
2325 return boolean_true_node;
2327 /* If VR is to the left of VAL, return false. */
2328 tst = compare_values (vr->max, val);
2329 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
2330 || (comp == GE_EXPR && tst == -1))
2331 return boolean_false_node;
2333 /* Otherwise, we don't know. */
2341 /* Debugging dumps. */
2343 void dump_value_range (FILE *, value_range_t *);
2344 void debug_value_range (value_range_t *);
2345 void dump_all_value_ranges (FILE *);
2346 void debug_all_value_ranges (void);
2347 void dump_vr_equiv (FILE *, bitmap);
2348 void debug_vr_equiv (bitmap);
2351 /* Dump value range VR to FILE. */
2354 dump_value_range (FILE *file, value_range_t *vr)
2357 fprintf (file, "[]");
2358 else if (vr->type == VR_UNDEFINED)
2359 fprintf (file, "UNDEFINED");
2360 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
2362 tree type = TREE_TYPE (vr->min);
2364 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
2366 if (INTEGRAL_TYPE_P (type)
2367 && !TYPE_UNSIGNED (type)
2368 && vr->min == TYPE_MIN_VALUE (type))
2369 fprintf (file, "-INF");
2371 print_generic_expr (file, vr->min, 0);
2373 fprintf (file, ", ");
2375 if (INTEGRAL_TYPE_P (type)
2376 && vr->max == TYPE_MAX_VALUE (type))
2377 fprintf (file, "+INF");
2379 print_generic_expr (file, vr->max, 0);
2381 fprintf (file, "]");
2388 fprintf (file, " EQUIVALENCES: { ");
2390 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
2392 print_generic_expr (file, ssa_name (i), 0);
2393 fprintf (file, " ");
2397 fprintf (file, "} (%u elements)", c);
2400 else if (vr->type == VR_VARYING)
2401 fprintf (file, "VARYING");
2403 fprintf (file, "INVALID RANGE");
2407 /* Dump value range VR to stderr. */
2410 debug_value_range (value_range_t *vr)
2412 dump_value_range (stderr, vr);
2413 fprintf (stderr, "\n");
2417 /* Dump value ranges of all SSA_NAMEs to FILE. */
2420 dump_all_value_ranges (FILE *file)
2424 for (i = 0; i < num_ssa_names; i++)
2428 print_generic_expr (file, ssa_name (i), 0);
2429 fprintf (file, ": ");
2430 dump_value_range (file, vr_value[i]);
2431 fprintf (file, "\n");
2435 fprintf (file, "\n");
2439 /* Dump all value ranges to stderr. */
2442 debug_all_value_ranges (void)
2444 dump_all_value_ranges (stderr);
2448 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
2449 create a new SSA name N and return the assertion assignment
2450 'V = ASSERT_EXPR <V, V OP W>'. */
2453 build_assert_expr_for (tree cond, tree v)
2457 gcc_assert (TREE_CODE (v) == SSA_NAME);
2458 n = duplicate_ssa_name (v, NULL_TREE);
2460 if (COMPARISON_CLASS_P (cond))
2462 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
2463 assertion = build2 (GIMPLE_MODIFY_STMT, TREE_TYPE (v), n, a);
2465 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
2467 /* Given !V, build the assignment N = false. */
2468 tree op0 = TREE_OPERAND (cond, 0);
2469 gcc_assert (op0 == v);
2470 assertion = build2 (GIMPLE_MODIFY_STMT, TREE_TYPE (v), n,
2471 boolean_false_node);
2473 else if (TREE_CODE (cond) == SSA_NAME)
2475 /* Given V, build the assignment N = true. */
2476 gcc_assert (v == cond);
2477 assertion = build2 (GIMPLE_MODIFY_STMT,
2478 TREE_TYPE (v), n, boolean_true_node);
2483 SSA_NAME_DEF_STMT (n) = assertion;
2485 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
2486 operand of the ASSERT_EXPR. Register the new name and the old one
2487 in the replacement table so that we can fix the SSA web after
2488 adding all the ASSERT_EXPRs. */
2489 register_new_name_mapping (n, v);
2495 /* Return false if EXPR is a predicate expression involving floating
2499 fp_predicate (tree expr)
2501 return (COMPARISON_CLASS_P (expr)
2502 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
2506 /* If the range of values taken by OP can be inferred after STMT executes,
2507 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2508 describes the inferred range. Return true if a range could be
2512 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
2515 *comp_code_p = ERROR_MARK;
2517 /* Do not attempt to infer anything in names that flow through
2519 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
2522 /* Similarly, don't infer anything from statements that may throw
2524 if (tree_could_throw_p (stmt))
2527 /* If STMT is the last statement of a basic block with no
2528 successors, there is no point inferring anything about any of its
2529 operands. We would not be able to find a proper insertion point
2530 for the assertion, anyway. */
2531 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
2534 /* We can only assume that a pointer dereference will yield
2535 non-NULL if -fdelete-null-pointer-checks is enabled. */
2536 if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op)))
2539 unsigned num_uses, num_derefs;
2541 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
2544 *val_p = build_int_cst (TREE_TYPE (op), 0);
2545 *comp_code_p = NE_EXPR;
2554 void dump_asserts_for (FILE *, tree);
2555 void debug_asserts_for (tree);
2556 void dump_all_asserts (FILE *);
2557 void debug_all_asserts (void);
2559 /* Dump all the registered assertions for NAME to FILE. */
2562 dump_asserts_for (FILE *file, tree name)
2566 fprintf (file, "Assertions to be inserted for ");
2567 print_generic_expr (file, name, 0);
2568 fprintf (file, "\n");
2570 loc = asserts_for[SSA_NAME_VERSION (name)];
2573 fprintf (file, "\t");
2574 print_generic_expr (file, bsi_stmt (loc->si), 0);
2575 fprintf (file, "\n\tBB #%d", loc->bb->index);
2578 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
2579 loc->e->dest->index);
2580 dump_edge_info (file, loc->e, 0);
2582 fprintf (file, "\n\tPREDICATE: ");
2583 print_generic_expr (file, name, 0);
2584 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
2585 print_generic_expr (file, loc->val, 0);
2586 fprintf (file, "\n\n");
2590 fprintf (file, "\n");
2594 /* Dump all the registered assertions for NAME to stderr. */
2597 debug_asserts_for (tree name)
2599 dump_asserts_for (stderr, name);
2603 /* Dump all the registered assertions for all the names to FILE. */
2606 dump_all_asserts (FILE *file)
2611 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
2612 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
2613 dump_asserts_for (file, ssa_name (i));
2614 fprintf (file, "\n");
2618 /* Dump all the registered assertions for all the names to stderr. */
2621 debug_all_asserts (void)
2623 dump_all_asserts (stderr);
2627 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2628 'NAME COMP_CODE VAL' at a location that dominates block BB or
2629 E->DEST, then register this location as a possible insertion point
2630 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2632 BB, E and SI provide the exact insertion point for the new
2633 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2634 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2635 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2636 must not be NULL. */
2639 register_new_assert_for (tree name,
2640 enum tree_code comp_code,
2644 block_stmt_iterator si)
2646 assert_locus_t n, loc, last_loc;
2648 basic_block dest_bb;
2650 #if defined ENABLE_CHECKING
2651 gcc_assert (bb == NULL || e == NULL);
2654 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
2655 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
2658 /* The new assertion A will be inserted at BB or E. We need to
2659 determine if the new location is dominated by a previously
2660 registered location for A. If we are doing an edge insertion,
2661 assume that A will be inserted at E->DEST. Note that this is not
2664 If E is a critical edge, it will be split. But even if E is
2665 split, the new block will dominate the same set of blocks that
2668 The reverse, however, is not true, blocks dominated by E->DEST
2669 will not be dominated by the new block created to split E. So,
2670 if the insertion location is on a critical edge, we will not use
2671 the new location to move another assertion previously registered
2672 at a block dominated by E->DEST. */
2673 dest_bb = (bb) ? bb : e->dest;
2675 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2676 VAL at a block dominating DEST_BB, then we don't need to insert a new
2677 one. Similarly, if the same assertion already exists at a block
2678 dominated by DEST_BB and the new location is not on a critical
2679 edge, then update the existing location for the assertion (i.e.,
2680 move the assertion up in the dominance tree).
2682 Note, this is implemented as a simple linked list because there
2683 should not be more than a handful of assertions registered per
2684 name. If this becomes a performance problem, a table hashed by
2685 COMP_CODE and VAL could be implemented. */
2686 loc = asserts_for[SSA_NAME_VERSION (name)];
2691 if (loc->comp_code == comp_code
2693 || operand_equal_p (loc->val, val, 0)))
2695 /* If the assertion NAME COMP_CODE VAL has already been
2696 registered at a basic block that dominates DEST_BB, then
2697 we don't need to insert the same assertion again. Note
2698 that we don't check strict dominance here to avoid
2699 replicating the same assertion inside the same basic
2700 block more than once (e.g., when a pointer is
2701 dereferenced several times inside a block).
2703 An exception to this rule are edge insertions. If the
2704 new assertion is to be inserted on edge E, then it will
2705 dominate all the other insertions that we may want to
2706 insert in DEST_BB. So, if we are doing an edge
2707 insertion, don't do this dominance check. */
2709 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
2712 /* Otherwise, if E is not a critical edge and DEST_BB
2713 dominates the existing location for the assertion, move
2714 the assertion up in the dominance tree by updating its
2715 location information. */
2716 if ((e == NULL || !EDGE_CRITICAL_P (e))
2717 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
2726 /* Update the last node of the list and move to the next one. */
2731 /* If we didn't find an assertion already registered for
2732 NAME COMP_CODE VAL, add a new one at the end of the list of
2733 assertions associated with NAME. */
2734 n = XNEW (struct assert_locus_d);
2738 n->comp_code = comp_code;
2745 asserts_for[SSA_NAME_VERSION (name)] = n;
2747 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
2750 /* COND is a predicate which uses NAME. Extract a suitable test code
2751 and value and store them into *CODE_P and *VAL_P so the predicate
2752 is normalized to NAME *CODE_P *VAL_P.
2754 If no extraction was possible, return FALSE, otherwise return TRUE.
2756 If INVERT is true, then we invert the result stored into *CODE_P. */
2759 extract_code_and_val_from_cond (tree name, tree cond, bool invert,
2760 enum tree_code *code_p, tree *val_p)
2762 enum tree_code comp_code;
2765 /* Predicates may be a single SSA name or NAME OP VAL. */
2768 /* If the predicate is a name, it must be NAME, in which
2769 case we create the predicate NAME == true or
2770 NAME == false accordingly. */
2771 comp_code = EQ_EXPR;
2772 val = invert ? boolean_false_node : boolean_true_node;
2776 /* Otherwise, we have a comparison of the form NAME COMP VAL
2777 or VAL COMP NAME. */
2778 if (name == TREE_OPERAND (cond, 1))
2780 /* If the predicate is of the form VAL COMP NAME, flip
2781 COMP around because we need to register NAME as the
2782 first operand in the predicate. */
2783 comp_code = swap_tree_comparison (TREE_CODE (cond));
2784 val = TREE_OPERAND (cond, 0);
2788 /* The comparison is of the form NAME COMP VAL, so the
2789 comparison code remains unchanged. */
2790 comp_code = TREE_CODE (cond);
2791 val = TREE_OPERAND (cond, 1);
2794 /* Invert the comparison code as necessary. */
2796 comp_code = invert_tree_comparison (comp_code, 0);
2798 /* VRP does not handle float types. */
2799 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)))
2802 /* Do not register always-false predicates.
2803 FIXME: this works around a limitation in fold() when dealing with
2804 enumerations. Given 'enum { N1, N2 } x;', fold will not
2805 fold 'if (x > N2)' to 'if (0)'. */
2806 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
2807 && INTEGRAL_TYPE_P (TREE_TYPE (val)))
2809 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
2810 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
2812 if (comp_code == GT_EXPR
2814 || compare_values (val, max) == 0))
2817 if (comp_code == LT_EXPR
2819 || compare_values (val, min) == 0))
2823 *code_p = comp_code;
2828 /* OP is an operand of a truth value expression which is known to have
2829 a particular value. Register any asserts for OP and for any
2830 operands in OP's defining statement.
2832 If CODE is EQ_EXPR, then we want to register OP is zero (false),
2833 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
2836 register_edge_assert_for_1 (tree op, enum tree_code code,
2837 edge e, block_stmt_iterator bsi)
2839 bool retval = false;
2840 tree op_def, rhs, val;
2842 /* We only care about SSA_NAMEs. */
2843 if (TREE_CODE (op) != SSA_NAME)
2846 /* We know that OP will have a zero or nonzero value. If OP is used
2847 more than once go ahead and register an assert for OP.
2849 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
2850 it will always be set for OP (because OP is used in a COND_EXPR in
2852 if (!has_single_use (op))
2854 val = build_int_cst (TREE_TYPE (op), 0);
2855 register_new_assert_for (op, code, val, NULL, e, bsi);
2859 /* Now look at how OP is set. If it's set from a comparison,
2860 a truth operation or some bit operations, then we may be able
2861 to register information about the operands of that assignment. */
2862 op_def = SSA_NAME_DEF_STMT (op);
2863 if (TREE_CODE (op_def) != GIMPLE_MODIFY_STMT)
2866 rhs = GIMPLE_STMT_OPERAND (op_def, 1);
2868 if (COMPARISON_CLASS_P (rhs))
2870 bool invert = (code == EQ_EXPR ? true : false);
2871 tree op0 = TREE_OPERAND (rhs, 0);
2872 tree op1 = TREE_OPERAND (rhs, 1);
2874 /* Conditionally register an assert for each SSA_NAME in the
2876 if (TREE_CODE (op0) == SSA_NAME
2877 && !has_single_use (op0)
2878 && extract_code_and_val_from_cond (op0, rhs,
2879 invert, &code, &val))
2881 register_new_assert_for (op0, code, val, NULL, e, bsi);
2885 /* Similarly for the second operand of the comparison. */
2886 if (TREE_CODE (op1) == SSA_NAME
2887 && !has_single_use (op1)
2888 && extract_code_and_val_from_cond (op1, rhs,
2889 invert, &code, &val))
2891 register_new_assert_for (op1, code, val, NULL, e, bsi);
2895 else if ((code == NE_EXPR
2896 && (TREE_CODE (rhs) == TRUTH_AND_EXPR
2897 || TREE_CODE (rhs) == BIT_AND_EXPR))
2899 && (TREE_CODE (rhs) == TRUTH_OR_EXPR
2900 || TREE_CODE (rhs) == BIT_IOR_EXPR)))
2902 /* Recurse on each operand. */
2903 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
2905 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 1),
2908 else if (TREE_CODE (rhs) == TRUTH_NOT_EXPR)
2910 /* Recurse, flipping CODE. */
2911 code = invert_tree_comparison (code, false);
2912 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
2915 else if (TREE_CODE (rhs) == SSA_NAME)
2917 /* Recurse through the copy. */
2918 retval |= register_edge_assert_for_1 (rhs, code, e, bsi);
2920 else if (TREE_CODE (rhs) == NOP_EXPR
2921 || TREE_CODE (rhs) == CONVERT_EXPR
2922 || TREE_CODE (rhs) == VIEW_CONVERT_EXPR
2923 || TREE_CODE (rhs) == NON_LVALUE_EXPR)
2925 /* Recurse through the type conversion. */
2926 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
2933 /* Try to register an edge assertion for SSA name NAME on edge E for
2934 the condition COND contributing to the conditional jump pointed to by SI.
2935 Return true if an assertion for NAME could be registered. */
2938 register_edge_assert_for (tree name, edge e, block_stmt_iterator si, tree cond)
2941 enum tree_code comp_code;
2942 bool retval = false;
2943 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
2945 /* Do not attempt to infer anything in names that flow through
2947 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
2950 if (!extract_code_and_val_from_cond (name, cond, is_else_edge,
2954 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
2955 reachable from E. */
2956 if (TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
2958 register_new_assert_for (name, comp_code, val, NULL, e, si);
2962 /* If COND is effectively an equality test of an SSA_NAME against
2963 the value zero or one, then we may be able to assert values
2964 for SSA_NAMEs which flow into COND. */
2966 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
2967 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
2968 have nonzero value. */
2969 if (((comp_code == EQ_EXPR && integer_onep (val))
2970 || (comp_code == NE_EXPR && integer_zerop (val))))
2972 tree def_stmt = SSA_NAME_DEF_STMT (name);
2974 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
2975 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_AND_EXPR
2976 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_AND_EXPR))
2978 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
2979 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
2980 retval |= register_edge_assert_for_1 (op0, NE_EXPR, e, si);
2981 retval |= register_edge_assert_for_1 (op1, NE_EXPR, e, si);
2985 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
2986 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
2988 if (((comp_code == EQ_EXPR && integer_zerop (val))
2989 || (comp_code == NE_EXPR && integer_onep (val))))
2991 tree def_stmt = SSA_NAME_DEF_STMT (name);
2993 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
2994 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_OR_EXPR
2995 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_IOR_EXPR))
2997 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
2998 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
2999 retval |= register_edge_assert_for_1 (op0, EQ_EXPR, e, si);
3000 retval |= register_edge_assert_for_1 (op1, EQ_EXPR, e, si);
3008 static bool find_assert_locations (basic_block bb);
3010 /* Determine whether the outgoing edges of BB should receive an
3011 ASSERT_EXPR for each of the operands of BB's LAST statement.
3012 The last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
3014 If any of the sub-graphs rooted at BB have an interesting use of
3015 the predicate operands, an assert location node is added to the
3016 list of assertions for the corresponding operands. */
3019 find_conditional_asserts (basic_block bb, tree last)
3022 block_stmt_iterator bsi;
3028 need_assert = false;
3029 bsi = bsi_for_stmt (last);
3031 /* Look for uses of the operands in each of the sub-graphs
3032 rooted at BB. We need to check each of the outgoing edges
3033 separately, so that we know what kind of ASSERT_EXPR to
3035 FOR_EACH_EDGE (e, ei, bb->succs)
3040 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
3041 Otherwise, when we finish traversing each of the sub-graphs, we
3042 won't know whether the variables were found in the sub-graphs or
3043 if they had been found in a block upstream from BB.
3045 This is actually a bad idea is some cases, particularly jump
3046 threading. Consider a CFG like the following:
3056 Assume that one or more operands in the conditional at the
3057 end of block 0 are used in a conditional in block 2, but not
3058 anywhere in block 1. In this case we will not insert any
3059 assert statements in block 1, which may cause us to miss
3060 opportunities to optimize, particularly for jump threading. */
3061 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3062 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3064 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3065 to determine if any of the operands in the conditional
3066 predicate are used. */
3068 need_assert |= find_assert_locations (e->dest);
3070 /* Register the necessary assertions for each operand in the
3071 conditional predicate. */
3072 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3073 need_assert |= register_edge_assert_for (op, e, bsi,
3074 COND_EXPR_COND (last));
3077 /* Finally, indicate that we have found the operands in the
3079 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3080 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3086 /* Traverse all the statements in block BB looking for statements that
3087 may generate useful assertions for the SSA names in their operand.
3088 If a statement produces a useful assertion A for name N_i, then the
3089 list of assertions already generated for N_i is scanned to
3090 determine if A is actually needed.
3092 If N_i already had the assertion A at a location dominating the
3093 current location, then nothing needs to be done. Otherwise, the
3094 new location for A is recorded instead.
3096 1- For every statement S in BB, all the variables used by S are
3097 added to bitmap FOUND_IN_SUBGRAPH.
3099 2- If statement S uses an operand N in a way that exposes a known
3100 value range for N, then if N was not already generated by an
3101 ASSERT_EXPR, create a new assert location for N. For instance,
3102 if N is a pointer and the statement dereferences it, we can
3103 assume that N is not NULL.
3105 3- COND_EXPRs are a special case of #2. We can derive range
3106 information from the predicate but need to insert different
3107 ASSERT_EXPRs for each of the sub-graphs rooted at the
3108 conditional block. If the last statement of BB is a conditional
3109 expression of the form 'X op Y', then
3111 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
3113 b) If the conditional is the only entry point to the sub-graph
3114 corresponding to the THEN_CLAUSE, recurse into it. On
3115 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
3116 an ASSERT_EXPR is added for the corresponding variable.
3118 c) Repeat step (b) on the ELSE_CLAUSE.
3120 d) Mark X and Y in FOUND_IN_SUBGRAPH.
3129 In this case, an assertion on the THEN clause is useful to
3130 determine that 'a' is always 9 on that edge. However, an assertion
3131 on the ELSE clause would be unnecessary.
3133 4- If BB does not end in a conditional expression, then we recurse
3134 into BB's dominator children.
3136 At the end of the recursive traversal, every SSA name will have a
3137 list of locations where ASSERT_EXPRs should be added. When a new
3138 location for name N is found, it is registered by calling
3139 register_new_assert_for. That function keeps track of all the
3140 registered assertions to prevent adding unnecessary assertions.
3141 For instance, if a pointer P_4 is dereferenced more than once in a
3142 dominator tree, only the location dominating all the dereference of
3143 P_4 will receive an ASSERT_EXPR.
3145 If this function returns true, then it means that there are names
3146 for which we need to generate ASSERT_EXPRs. Those assertions are
3147 inserted by process_assert_insertions.
3149 TODO. Handle SWITCH_EXPR. */
3152 find_assert_locations (basic_block bb)
3154 block_stmt_iterator si;
3159 if (TEST_BIT (blocks_visited, bb->index))
3162 SET_BIT (blocks_visited, bb->index);
3164 need_assert = false;
3166 /* Traverse all PHI nodes in BB marking used operands. */
3167 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3169 use_operand_p arg_p;
3172 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
3174 tree arg = USE_FROM_PTR (arg_p);
3175 if (TREE_CODE (arg) == SSA_NAME)
3177 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
3178 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
3183 /* Traverse all the statements in BB marking used names and looking
3184 for statements that may infer assertions for their used operands. */
3186 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3191 stmt = bsi_stmt (si);
3193 /* See if we can derive an assertion for any of STMT's operands. */
3194 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
3197 enum tree_code comp_code;
3199 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
3200 the sub-graph of a conditional block, when we return from
3201 this recursive walk, our parent will use the
3202 FOUND_IN_SUBGRAPH bitset to determine if one of the
3203 operands it was looking for was present in the sub-graph. */
3204 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3206 /* If OP is used in such a way that we can infer a value
3207 range for it, and we don't find a previous assertion for
3208 it, create a new assertion location node for OP. */
3209 if (infer_value_range (stmt, op, &comp_code, &value))
3211 /* If we are able to infer a nonzero value range for OP,
3212 then walk backwards through the use-def chain to see if OP
3213 was set via a typecast.
3215 If so, then we can also infer a nonzero value range
3216 for the operand of the NOP_EXPR. */
3217 if (comp_code == NE_EXPR && integer_zerop (value))
3220 tree def_stmt = SSA_NAME_DEF_STMT (t);
3222 while (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3224 (GIMPLE_STMT_OPERAND (def_stmt, 1)) == NOP_EXPR
3226 (TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1),
3229 (TREE_TYPE (TREE_OPERAND
3230 (GIMPLE_STMT_OPERAND (def_stmt,
3233 t = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3234 def_stmt = SSA_NAME_DEF_STMT (t);
3236 /* Note we want to register the assert for the
3237 operand of the NOP_EXPR after SI, not after the
3239 if (! has_single_use (t))
3241 register_new_assert_for (t, comp_code, value,
3248 /* If OP is used only once, namely in this STMT, don't
3249 bother creating an ASSERT_EXPR for it. Such an
3250 ASSERT_EXPR would do nothing but increase compile time. */
3251 if (!has_single_use (op))
3253 register_new_assert_for (op, comp_code, value, bb, NULL, si);
3259 /* Remember the last statement of the block. */
3263 /* If BB's last statement is a conditional expression
3264 involving integer operands, recurse into each of the sub-graphs
3265 rooted at BB to determine if we need to add ASSERT_EXPRs. */
3267 && TREE_CODE (last) == COND_EXPR
3268 && !fp_predicate (COND_EXPR_COND (last))
3269 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
3270 need_assert |= find_conditional_asserts (bb, last);
3272 /* Recurse into the dominator children of BB. */
3273 for (son = first_dom_son (CDI_DOMINATORS, bb);
3275 son = next_dom_son (CDI_DOMINATORS, son))
3276 need_assert |= find_assert_locations (son);
3282 /* Create an ASSERT_EXPR for NAME and insert it in the location
3283 indicated by LOC. Return true if we made any edge insertions. */
3286 process_assert_insertions_for (tree name, assert_locus_t loc)
3288 /* Build the comparison expression NAME_i COMP_CODE VAL. */
3289 tree stmt, cond, assert_expr;
3293 cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
3294 assert_expr = build_assert_expr_for (cond, name);
3298 /* We have been asked to insert the assertion on an edge. This
3299 is used only by COND_EXPR and SWITCH_EXPR assertions. */
3300 #if defined ENABLE_CHECKING
3301 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
3302 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
3305 bsi_insert_on_edge (loc->e, assert_expr);
3309 /* Otherwise, we can insert right after LOC->SI iff the
3310 statement must not be the last statement in the block. */
3311 stmt = bsi_stmt (loc->si);
3312 if (!stmt_ends_bb_p (stmt))
3314 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
3318 /* If STMT must be the last statement in BB, we can only insert new
3319 assertions on the non-abnormal edge out of BB. Note that since
3320 STMT is not control flow, there may only be one non-abnormal edge
3322 FOR_EACH_EDGE (e, ei, loc->bb->succs)
3323 if (!(e->flags & EDGE_ABNORMAL))
3325 bsi_insert_on_edge (e, assert_expr);
3333 /* Process all the insertions registered for every name N_i registered
3334 in NEED_ASSERT_FOR. The list of assertions to be inserted are
3335 found in ASSERTS_FOR[i]. */
3338 process_assert_insertions (void)
3342 bool update_edges_p = false;
3343 int num_asserts = 0;
3345 if (dump_file && (dump_flags & TDF_DETAILS))
3346 dump_all_asserts (dump_file);
3348 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3350 assert_locus_t loc = asserts_for[i];
3355 assert_locus_t next = loc->next;
3356 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
3364 bsi_commit_edge_inserts ();
3366 if (dump_file && (dump_flags & TDF_STATS))
3367 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
3372 /* Traverse the flowgraph looking for conditional jumps to insert range
3373 expressions. These range expressions are meant to provide information
3374 to optimizations that need to reason in terms of value ranges. They
3375 will not be expanded into RTL. For instance, given:
3384 this pass will transform the code into:
3390 x = ASSERT_EXPR <x, x < y>
3395 y = ASSERT_EXPR <y, x <= y>
3399 The idea is that once copy and constant propagation have run, other
3400 optimizations will be able to determine what ranges of values can 'x'
3401 take in different paths of the code, simply by checking the reaching
3402 definition of 'x'. */
3405 insert_range_assertions (void)
3411 found_in_subgraph = sbitmap_alloc (num_ssa_names);
3412 sbitmap_zero (found_in_subgraph);
3414 blocks_visited = sbitmap_alloc (last_basic_block);
3415 sbitmap_zero (blocks_visited);
3417 need_assert_for = BITMAP_ALLOC (NULL);
3418 asserts_for = XCNEWVEC (assert_locus_t, num_ssa_names);
3420 calculate_dominance_info (CDI_DOMINATORS);
3422 update_ssa_p = false;
3423 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3424 if (find_assert_locations (e->dest))
3425 update_ssa_p = true;
3429 process_assert_insertions ();
3430 update_ssa (TODO_update_ssa_no_phi);
3433 if (dump_file && (dump_flags & TDF_DETAILS))
3435 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
3436 dump_function_to_file (current_function_decl, dump_file, dump_flags);
3439 sbitmap_free (found_in_subgraph);
3441 BITMAP_FREE (need_assert_for);
3445 /* Convert range assertion expressions into the implied copies and
3446 copy propagate away the copies. Doing the trivial copy propagation
3447 here avoids the need to run the full copy propagation pass after
3450 FIXME, this will eventually lead to copy propagation removing the
3451 names that had useful range information attached to them. For
3452 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
3453 then N_i will have the range [3, +INF].
3455 However, by converting the assertion into the implied copy
3456 operation N_i = N_j, we will then copy-propagate N_j into the uses
3457 of N_i and lose the range information. We may want to hold on to
3458 ASSERT_EXPRs a little while longer as the ranges could be used in
3459 things like jump threading.
3461 The problem with keeping ASSERT_EXPRs around is that passes after
3462 VRP need to handle them appropriately.
3464 Another approach would be to make the range information a first
3465 class property of the SSA_NAME so that it can be queried from
3466 any pass. This is made somewhat more complex by the need for
3467 multiple ranges to be associated with one SSA_NAME. */
3470 remove_range_assertions (void)
3473 block_stmt_iterator si;
3475 /* Note that the BSI iterator bump happens at the bottom of the
3476 loop and no bump is necessary if we're removing the statement
3477 referenced by the current BSI. */
3479 for (si = bsi_start (bb); !bsi_end_p (si);)
3481 tree stmt = bsi_stmt (si);
3484 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
3485 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ASSERT_EXPR)
3487 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1), var;
3488 tree cond = fold (ASSERT_EXPR_COND (rhs));
3489 use_operand_p use_p;
3490 imm_use_iterator iter;
3492 gcc_assert (cond != boolean_false_node);
3494 /* Propagate the RHS into every use of the LHS. */
3495 var = ASSERT_EXPR_VAR (rhs);
3496 FOR_EACH_IMM_USE_STMT (use_stmt, iter,
3497 GIMPLE_STMT_OPERAND (stmt, 0))
3498 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
3500 SET_USE (use_p, var);
3501 gcc_assert (TREE_CODE (var) == SSA_NAME);
3504 /* And finally, remove the copy, it is not needed. */
3505 bsi_remove (&si, true);
3511 sbitmap_free (blocks_visited);
3515 /* Return true if STMT is interesting for VRP. */
3518 stmt_interesting_for_vrp (tree stmt)
3520 if (TREE_CODE (stmt) == PHI_NODE
3521 && is_gimple_reg (PHI_RESULT (stmt))
3522 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
3523 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
3525 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
3527 tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
3528 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
3530 /* In general, assignments with virtual operands are not useful
3531 for deriving ranges, with the obvious exception of calls to
3532 builtin functions. */
3533 if (TREE_CODE (lhs) == SSA_NAME
3534 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3535 || POINTER_TYPE_P (TREE_TYPE (lhs)))
3536 && ((TREE_CODE (rhs) == CALL_EXPR
3537 && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR
3538 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))
3539 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)))
3540 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)))
3543 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
3550 /* Initialize local data structures for VRP. */
3553 vrp_initialize (void)
3557 vr_value = XCNEWVEC (value_range_t *, num_ssa_names);
3561 block_stmt_iterator si;
3564 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3566 if (!stmt_interesting_for_vrp (phi))
3568 tree lhs = PHI_RESULT (phi);
3569 set_value_range_to_varying (get_value_range (lhs));
3570 DONT_SIMULATE_AGAIN (phi) = true;
3573 DONT_SIMULATE_AGAIN (phi) = false;
3576 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3578 tree stmt = bsi_stmt (si);
3580 if (!stmt_interesting_for_vrp (stmt))
3584 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
3585 set_value_range_to_varying (get_value_range (def));
3586 DONT_SIMULATE_AGAIN (stmt) = true;
3590 DONT_SIMULATE_AGAIN (stmt) = false;
3597 /* Visit assignment STMT. If it produces an interesting range, record
3598 the SSA name in *OUTPUT_P. */
3600 static enum ssa_prop_result
3601 vrp_visit_assignment (tree stmt, tree *output_p)
3606 lhs = GIMPLE_STMT_OPERAND (stmt, 0);
3607 rhs = GIMPLE_STMT_OPERAND (stmt, 1);
3609 /* We only keep track of ranges in integral and pointer types. */
3610 if (TREE_CODE (lhs) == SSA_NAME
3611 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
3612 /* It is valid to have NULL MIN/MAX values on a type. See
3613 build_range_type. */
3614 && TYPE_MIN_VALUE (TREE_TYPE (lhs))
3615 && TYPE_MAX_VALUE (TREE_TYPE (lhs)))
3616 || POINTER_TYPE_P (TREE_TYPE (lhs))))
3619 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
3621 extract_range_from_expr (&new_vr, rhs);
3623 /* If STMT is inside a loop, we may be able to know something
3624 else about the range of LHS by examining scalar evolution
3626 if (current_loops && (l = loop_containing_stmt (stmt)))
3627 adjust_range_with_scev (&new_vr, l, stmt, lhs);
3629 if (update_value_range (lhs, &new_vr))
3633 if (dump_file && (dump_flags & TDF_DETAILS))
3635 fprintf (dump_file, "Found new range for ");
3636 print_generic_expr (dump_file, lhs, 0);
3637 fprintf (dump_file, ": ");
3638 dump_value_range (dump_file, &new_vr);
3639 fprintf (dump_file, "\n\n");
3642 if (new_vr.type == VR_VARYING)
3643 return SSA_PROP_VARYING;
3645 return SSA_PROP_INTERESTING;
3648 return SSA_PROP_NOT_INTERESTING;
3651 /* Every other statement produces no useful ranges. */
3652 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
3653 set_value_range_to_varying (get_value_range (def));
3655 return SSA_PROP_VARYING;
3659 /* Compare all the value ranges for names equivalent to VAR with VAL
3660 using comparison code COMP. Return the same value returned by
3661 compare_range_with_value. */
3664 compare_name_with_value (enum tree_code comp, tree var, tree val)
3671 t = retval = NULL_TREE;
3673 /* Get the set of equivalences for VAR. */
3674 e = get_value_range (var)->equiv;
3676 /* Add VAR to its own set of equivalences so that VAR's value range
3677 is processed by this loop (otherwise, we would have to replicate
3678 the body of the loop just to check VAR's value range). */
3679 bitmap_set_bit (e, SSA_NAME_VERSION (var));
3681 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
3683 value_range_t equiv_vr = *(vr_value[i]);
3685 /* If name N_i does not have a valid range, use N_i as its own
3686 range. This allows us to compare against names that may
3687 have N_i in their ranges. */
3688 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
3690 equiv_vr.type = VR_RANGE;
3691 equiv_vr.min = ssa_name (i);
3692 equiv_vr.max = ssa_name (i);
3695 t = compare_range_with_value (comp, &equiv_vr, val);
3698 /* If we get different answers from different members
3699 of the equivalence set this check must be in a dead
3700 code region. Folding it to a trap representation
3701 would be correct here. For now just return don't-know. */
3712 /* Remove VAR from its own equivalence set. */
3713 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
3718 /* We couldn't find a non-NULL value for the predicate. */
3723 /* Given a comparison code COMP and names N1 and N2, compare all the
3724 ranges equivalent to N1 against all the ranges equivalent to N2
3725 to determine the value of N1 COMP N2. Return the same value
3726 returned by compare_ranges. */
3729 compare_names (enum tree_code comp, tree n1, tree n2)
3733 bitmap_iterator bi1, bi2;
3736 /* Compare the ranges of every name equivalent to N1 against the
3737 ranges of every name equivalent to N2. */
3738 e1 = get_value_range (n1)->equiv;
3739 e2 = get_value_range (n2)->equiv;
3741 /* Add N1 and N2 to their own set of equivalences to avoid
3742 duplicating the body of the loop just to check N1 and N2
3744 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
3745 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
3747 /* If the equivalence sets have a common intersection, then the two
3748 names can be compared without checking their ranges. */
3749 if (bitmap_intersect_p (e1, e2))
3751 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3752 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3754 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
3756 : boolean_false_node;
3759 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3760 N2 to their own set of equivalences to avoid duplicating the body
3761 of the loop just to check N1 and N2 ranges. */
3762 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
3764 value_range_t vr1 = *(vr_value[i1]);
3766 /* If the range is VARYING or UNDEFINED, use the name itself. */
3767 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
3769 vr1.type = VR_RANGE;
3770 vr1.min = ssa_name (i1);
3771 vr1.max = ssa_name (i1);
3774 t = retval = NULL_TREE;
3775 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
3777 value_range_t vr2 = *(vr_value[i2]);
3779 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
3781 vr2.type = VR_RANGE;
3782 vr2.min = ssa_name (i2);
3783 vr2.max = ssa_name (i2);
3786 t = compare_ranges (comp, &vr1, &vr2);
3789 /* If we get different answers from different members
3790 of the equivalence set this check must be in a dead
3791 code region. Folding it to a trap representation
3792 would be correct here. For now just return don't-know. */
3796 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3797 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3806 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3807 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3812 /* None of the equivalent ranges are useful in computing this
3814 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
3815 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
3820 /* Given a conditional predicate COND, try to determine if COND yields
3821 true or false based on the value ranges of its operands. Return
3822 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3823 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3824 NULL if the conditional cannot be evaluated at compile time.
3826 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3827 the operands in COND are used when trying to compute its value.
3828 This is only used during final substitution. During propagation,
3829 we only check the range of each variable and not its equivalents. */
3832 vrp_evaluate_conditional (tree cond, bool use_equiv_p)
3834 gcc_assert (TREE_CODE (cond) == SSA_NAME
3835 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
3837 if (TREE_CODE (cond) == SSA_NAME)
3843 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node);
3846 value_range_t *vr = get_value_range (cond);
3847 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node);
3850 /* If COND has a known boolean range, return it. */
3854 /* Otherwise, if COND has a symbolic range of exactly one value,
3856 vr = get_value_range (cond);
3857 if (vr->type == VR_RANGE && vr->min == vr->max)
3862 tree op0 = TREE_OPERAND (cond, 0);
3863 tree op1 = TREE_OPERAND (cond, 1);
3865 /* We only deal with integral and pointer types. */
3866 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
3867 && !POINTER_TYPE_P (TREE_TYPE (op0)))
3872 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
3873 return compare_names (TREE_CODE (cond), op0, op1);
3874 else if (TREE_CODE (op0) == SSA_NAME)
3875 return compare_name_with_value (TREE_CODE (cond), op0, op1);
3876 else if (TREE_CODE (op1) == SSA_NAME)
3877 return compare_name_with_value (
3878 swap_tree_comparison (TREE_CODE (cond)), op1, op0);
3882 value_range_t *vr0, *vr1;
3884 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
3885 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
3888 return compare_ranges (TREE_CODE (cond), vr0, vr1);
3889 else if (vr0 && vr1 == NULL)
3890 return compare_range_with_value (TREE_CODE (cond), vr0, op1);
3891 else if (vr0 == NULL && vr1)
3892 return compare_range_with_value (
3893 swap_tree_comparison (TREE_CODE (cond)), vr1, op0);
3897 /* Anything else cannot be computed statically. */
3902 /* Visit conditional statement STMT. If we can determine which edge
3903 will be taken out of STMT's basic block, record it in
3904 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3905 SSA_PROP_VARYING. */
3907 static enum ssa_prop_result
3908 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
3912 *taken_edge_p = NULL;
3914 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3915 add ASSERT_EXPRs for them. */
3916 if (TREE_CODE (stmt) == SWITCH_EXPR)
3917 return SSA_PROP_VARYING;
3919 cond = COND_EXPR_COND (stmt);
3921 if (dump_file && (dump_flags & TDF_DETAILS))
3926 fprintf (dump_file, "\nVisiting conditional with predicate: ");
3927 print_generic_expr (dump_file, cond, 0);
3928 fprintf (dump_file, "\nWith known ranges\n");
3930 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
3932 fprintf (dump_file, "\t");
3933 print_generic_expr (dump_file, use, 0);
3934 fprintf (dump_file, ": ");
3935 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
3938 fprintf (dump_file, "\n");
3941 /* Compute the value of the predicate COND by checking the known
3942 ranges of each of its operands.
3944 Note that we cannot evaluate all the equivalent ranges here
3945 because those ranges may not yet be final and with the current
3946 propagation strategy, we cannot determine when the value ranges
3947 of the names in the equivalence set have changed.
3949 For instance, given the following code fragment
3953 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3957 Assume that on the first visit to i_14, i_5 has the temporary
3958 range [8, 8] because the second argument to the PHI function is
3959 not yet executable. We derive the range ~[0, 0] for i_14 and the
3960 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3961 the first time, since i_14 is equivalent to the range [8, 8], we
3962 determine that the predicate is always false.
3964 On the next round of propagation, i_13 is determined to be
3965 VARYING, which causes i_5 to drop down to VARYING. So, another
3966 visit to i_14 is scheduled. In this second visit, we compute the
3967 exact same range and equivalence set for i_14, namely ~[0, 0] and
3968 { i_5 }. But we did not have the previous range for i_5
3969 registered, so vrp_visit_assignment thinks that the range for
3970 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3971 is not visited again, which stops propagation from visiting
3972 statements in the THEN clause of that if().
3974 To properly fix this we would need to keep the previous range
3975 value for the names in the equivalence set. This way we would've
3976 discovered that from one visit to the other i_5 changed from
3977 range [8, 8] to VR_VARYING.
3979 However, fixing this apparent limitation may not be worth the
3980 additional checking. Testing on several code bases (GCC, DLV,
3981 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3982 4 more predicates folded in SPEC. */
3983 val = vrp_evaluate_conditional (cond, false);
3985 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
3987 if (dump_file && (dump_flags & TDF_DETAILS))
3989 fprintf (dump_file, "\nPredicate evaluates to: ");
3990 if (val == NULL_TREE)
3991 fprintf (dump_file, "DON'T KNOW\n");
3993 print_generic_stmt (dump_file, val, 0);
3996 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
4000 /* Evaluate statement STMT. If the statement produces a useful range,
4001 return SSA_PROP_INTERESTING and record the SSA name with the
4002 interesting range into *OUTPUT_P.
4004 If STMT is a conditional branch and we can determine its truth
4005 value, the taken edge is recorded in *TAKEN_EDGE_P.
4007 If STMT produces a varying value, return SSA_PROP_VARYING. */
4009 static enum ssa_prop_result
4010 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
4016 if (dump_file && (dump_flags & TDF_DETAILS))
4018 fprintf (dump_file, "\nVisiting statement:\n");
4019 print_generic_stmt (dump_file, stmt, dump_flags);
4020 fprintf (dump_file, "\n");
4023 ann = stmt_ann (stmt);
4024 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4026 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4028 /* In general, assignments with virtual operands are not useful
4029 for deriving ranges, with the obvious exception of calls to
4030 builtin functions. */
4031 if ((TREE_CODE (rhs) == CALL_EXPR
4032 && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR
4033 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))
4034 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)))
4035 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
4036 return vrp_visit_assignment (stmt, output_p);
4038 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
4039 return vrp_visit_cond_stmt (stmt, taken_edge_p);
4041 /* All other statements produce nothing of interest for VRP, so mark
4042 their outputs varying and prevent further simulation. */
4043 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
4044 set_value_range_to_varying (get_value_range (def));
4046 return SSA_PROP_VARYING;
4050 /* Meet operation for value ranges. Given two value ranges VR0 and
4051 VR1, store in VR0 a range that contains both VR0 and VR1. This
4052 may not be the smallest possible such range. */
4055 vrp_meet (value_range_t *vr0, value_range_t *vr1)
4057 if (vr0->type == VR_UNDEFINED)
4059 copy_value_range (vr0, vr1);
4063 if (vr1->type == VR_UNDEFINED)
4065 /* Nothing to do. VR0 already has the resulting range. */
4069 if (vr0->type == VR_VARYING)
4071 /* Nothing to do. VR0 already has the resulting range. */
4075 if (vr1->type == VR_VARYING)
4077 set_value_range_to_varying (vr0);
4081 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
4086 /* Compute the convex hull of the ranges. The lower limit of
4087 the new range is the minimum of the two ranges. If they
4088 cannot be compared, then give up. */
4089 cmp = compare_values (vr0->min, vr1->min);
4090 if (cmp == 0 || cmp == 1)
4097 /* Similarly, the upper limit of the new range is the maximum
4098 of the two ranges. If they cannot be compared, then
4100 cmp = compare_values (vr0->max, vr1->max);
4101 if (cmp == 0 || cmp == -1)
4108 /* The resulting set of equivalences is the intersection of
4110 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4111 bitmap_and_into (vr0->equiv, vr1->equiv);
4112 else if (vr0->equiv && !vr1->equiv)
4113 bitmap_clear (vr0->equiv);
4115 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
4117 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
4119 /* Two anti-ranges meet only if their complements intersect.
4120 Only handle the case of identical ranges. */
4121 if (compare_values (vr0->min, vr1->min) == 0
4122 && compare_values (vr0->max, vr1->max) == 0
4123 && compare_values (vr0->min, vr0->max) == 0)
4125 /* The resulting set of equivalences is the intersection of
4127 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4128 bitmap_and_into (vr0->equiv, vr1->equiv);
4129 else if (vr0->equiv && !vr1->equiv)
4130 bitmap_clear (vr0->equiv);
4135 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
4137 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
4138 only handle the case where the ranges have an empty intersection.
4139 The result of the meet operation is the anti-range. */
4140 if (!symbolic_range_p (vr0)
4141 && !symbolic_range_p (vr1)
4142 && !value_ranges_intersect_p (vr0, vr1))
4144 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
4145 set. We need to compute the intersection of the two
4146 equivalence sets. */
4147 if (vr1->type == VR_ANTI_RANGE)
4148 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
4150 /* The resulting set of equivalences is the intersection of
4152 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4153 bitmap_and_into (vr0->equiv, vr1->equiv);
4154 else if (vr0->equiv && !vr1->equiv)
4155 bitmap_clear (vr0->equiv);
4166 /* Failed to find an efficient meet. Before giving up and setting
4167 the result to VARYING, see if we can at least derive a useful
4168 anti-range. FIXME, all this nonsense about distinguishing
4169 anti-ranges from ranges is necessary because of the odd
4170 semantics of range_includes_zero_p and friends. */
4171 if (!symbolic_range_p (vr0)
4172 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
4173 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
4174 && !symbolic_range_p (vr1)
4175 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
4176 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
4178 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
4180 /* Since this meet operation did not result from the meeting of
4181 two equivalent names, VR0 cannot have any equivalences. */
4183 bitmap_clear (vr0->equiv);
4186 set_value_range_to_varying (vr0);
4190 /* Visit all arguments for PHI node PHI that flow through executable
4191 edges. If a valid value range can be derived from all the incoming
4192 value ranges, set a new range for the LHS of PHI. */
4194 static enum ssa_prop_result
4195 vrp_visit_phi_node (tree phi)
4198 tree lhs = PHI_RESULT (phi);
4199 value_range_t *lhs_vr = get_value_range (lhs);
4200 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
4201 bool all_const = true;
4203 copy_value_range (&vr_result, lhs_vr);
4205 if (dump_file && (dump_flags & TDF_DETAILS))
4207 fprintf (dump_file, "\nVisiting PHI node: ");
4208 print_generic_expr (dump_file, phi, dump_flags);
4211 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
4213 edge e = PHI_ARG_EDGE (phi, i);
4215 if (dump_file && (dump_flags & TDF_DETAILS))
4218 "\n Argument #%d (%d -> %d %sexecutable)\n",
4219 i, e->src->index, e->dest->index,
4220 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
4223 if (e->flags & EDGE_EXECUTABLE)
4225 tree arg = PHI_ARG_DEF (phi, i);
4226 value_range_t vr_arg;
4228 if (TREE_CODE (arg) == SSA_NAME)
4230 vr_arg = *(get_value_range (arg));
4235 vr_arg.type = VR_RANGE;
4238 vr_arg.equiv = NULL;
4241 if (dump_file && (dump_flags & TDF_DETAILS))
4243 fprintf (dump_file, "\t");
4244 print_generic_expr (dump_file, arg, dump_flags);
4245 fprintf (dump_file, "\n\tValue: ");
4246 dump_value_range (dump_file, &vr_arg);
4247 fprintf (dump_file, "\n");
4250 vrp_meet (&vr_result, &vr_arg);
4252 if (vr_result.type == VR_VARYING)
4257 if (vr_result.type == VR_VARYING)
4260 /* To prevent infinite iterations in the algorithm, derive ranges
4261 when the new value is slightly bigger or smaller than the
4263 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE
4266 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
4268 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
4269 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
4271 /* If the new minimum is smaller or larger than the previous
4272 one, go all the way to -INF. In the first case, to avoid
4273 iterating millions of times to reach -INF, and in the
4274 other case to avoid infinite bouncing between different
4276 if (cmp_min > 0 || cmp_min < 0)
4277 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
4279 /* Similarly, if the new maximum is smaller or larger than
4280 the previous one, go all the way to +INF. */
4281 if (cmp_max < 0 || cmp_max > 0)
4282 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
4284 /* If we ended up with a (-INF, +INF) range, set it to
4286 if (vr_result.min == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))
4287 && vr_result.max == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)))
4292 /* If the new range is different than the previous value, keep
4294 if (update_value_range (lhs, &vr_result))
4295 return SSA_PROP_INTERESTING;
4297 /* Nothing changed, don't add outgoing edges. */
4298 return SSA_PROP_NOT_INTERESTING;
4300 /* No match found. Set the LHS to VARYING. */
4302 set_value_range_to_varying (lhs_vr);
4303 return SSA_PROP_VARYING;
4306 /* Simplify a division or modulo operator to a right shift or
4307 bitwise and if the first operand is unsigned or is greater
4308 than zero and the second operand is an exact power of two. */
4311 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
4314 tree op = TREE_OPERAND (rhs, 0);
4315 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
4317 if (TYPE_UNSIGNED (TREE_TYPE (op)))
4319 val = integer_one_node;
4323 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node);
4326 if (val && integer_onep (val))
4329 tree op0 = TREE_OPERAND (rhs, 0);
4330 tree op1 = TREE_OPERAND (rhs, 1);
4332 if (rhs_code == TRUNC_DIV_EXPR)
4334 t = build_int_cst (NULL_TREE, tree_log2 (op1));
4335 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
4339 t = build_int_cst (TREE_TYPE (op1), 1);
4340 t = int_const_binop (MINUS_EXPR, op1, t, 0);
4341 t = fold_convert (TREE_TYPE (op0), t);
4342 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
4345 GIMPLE_STMT_OPERAND (stmt, 1) = t;
4350 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
4351 ABS_EXPR. If the operand is <= 0, then simplify the
4352 ABS_EXPR into a NEGATE_EXPR. */
4355 simplify_abs_using_ranges (tree stmt, tree rhs)
4358 tree op = TREE_OPERAND (rhs, 0);
4359 tree type = TREE_TYPE (op);
4360 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
4362 if (TYPE_UNSIGNED (type))
4364 val = integer_zero_node;
4368 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node);
4371 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node);
4375 if (integer_zerop (val))
4376 val = integer_one_node;
4377 else if (integer_onep (val))
4378 val = integer_zero_node;
4383 && (integer_onep (val) || integer_zerop (val)))
4387 if (integer_onep (val))
4388 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
4392 GIMPLE_STMT_OPERAND (stmt, 1) = t;
4398 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
4399 a known value range VR.
4401 If there is one and only one value which will satisfy the
4402 conditional, then return that value. Else return NULL. */
4405 test_for_singularity (enum tree_code cond_code, tree op0,
4406 tree op1, value_range_t *vr)
4411 /* Extract minimum/maximum values which satisfy the
4412 the conditional as it was written. */
4413 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
4415 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
4418 if (cond_code == LT_EXPR)
4420 tree one = build_int_cst (TREE_TYPE (op0), 1);
4421 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
4424 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
4426 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
4429 if (cond_code == GT_EXPR)
4431 tree one = build_int_cst (TREE_TYPE (op0), 1);
4432 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
4436 /* Now refine the minimum and maximum values using any
4437 value range information we have for op0. */
4440 if (compare_values (vr->min, min) == -1)
4444 if (compare_values (vr->max, max) == 1)
4449 /* If the new min/max values have converged to a single value,
4450 then there is only one value which can satisfy the condition,
4451 return that value. */
4452 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
4458 /* Simplify a conditional using a relational operator to an equality
4459 test if the range information indicates only one value can satisfy
4460 the original conditional. */
4463 simplify_cond_using_ranges (tree stmt)
4465 tree cond = COND_EXPR_COND (stmt);
4466 tree op0 = TREE_OPERAND (cond, 0);
4467 tree op1 = TREE_OPERAND (cond, 1);
4468 enum tree_code cond_code = TREE_CODE (cond);
4470 if (cond_code != NE_EXPR
4471 && cond_code != EQ_EXPR
4472 && TREE_CODE (op0) == SSA_NAME
4473 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
4474 && is_gimple_min_invariant (op1))
4476 value_range_t *vr = get_value_range (op0);
4478 /* If we have range information for OP0, then we might be
4479 able to simplify this conditional. */
4480 if (vr->type == VR_RANGE)
4482 tree new = test_for_singularity (cond_code, op0, op1, vr);
4488 fprintf (dump_file, "Simplified relational ");
4489 print_generic_expr (dump_file, cond, 0);
4490 fprintf (dump_file, " into ");
4493 COND_EXPR_COND (stmt)
4494 = build2 (EQ_EXPR, boolean_type_node, op0, new);
4499 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4500 fprintf (dump_file, "\n");
4506 /* Try again after inverting the condition. We only deal
4507 with integral types here, so no need to worry about
4508 issues with inverting FP comparisons. */
4509 cond_code = invert_tree_comparison (cond_code, false);
4510 new = test_for_singularity (cond_code, op0, op1, vr);
4516 fprintf (dump_file, "Simplified relational ");
4517 print_generic_expr (dump_file, cond, 0);
4518 fprintf (dump_file, " into ");
4521 COND_EXPR_COND (stmt)
4522 = build2 (NE_EXPR, boolean_type_node, op0, new);
4527 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
4528 fprintf (dump_file, "\n");
4537 /* Simplify STMT using ranges if possible. */
4540 simplify_stmt_using_ranges (tree stmt)
4542 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4544 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4545 enum tree_code rhs_code = TREE_CODE (rhs);
4547 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
4548 and BIT_AND_EXPR respectively if the first operand is greater
4549 than zero and the second operand is an exact power of two. */
4550 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
4551 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
4552 && integer_pow2p (TREE_OPERAND (rhs, 1)))
4553 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
4555 /* Transform ABS (X) into X or -X as appropriate. */
4556 if (rhs_code == ABS_EXPR
4557 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
4558 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
4559 simplify_abs_using_ranges (stmt, rhs);
4561 else if (TREE_CODE (stmt) == COND_EXPR
4562 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
4564 simplify_cond_using_ranges (stmt);
4568 /* Stack of dest,src equivalency pairs that need to be restored after
4569 each attempt to thread a block's incoming edge to an outgoing edge.
4571 A NULL entry is used to mark the end of pairs which need to be
4573 static VEC(tree,heap) *stack;
4575 /* A trivial wrapper so that we can present the generic jump
4576 threading code with a simple API for simplifying statements. */
4578 simplify_stmt_for_jump_threading (tree stmt)
4580 /* We only use VRP information to simplify conditionals. This is
4581 overly conservative, but it's unclear if doing more would be
4582 worth the compile time cost. */
4583 if (TREE_CODE (stmt) != COND_EXPR)
4586 return vrp_evaluate_conditional (COND_EXPR_COND (stmt), true);
4589 /* Blocks which have more than one predecessor and more than
4590 one successor present jump threading opportunities. ie,
4591 when the block is reached from a specific predecessor, we
4592 may be able to determine which of the outgoing edges will
4593 be traversed. When this optimization applies, we are able
4594 to avoid conditionals at runtime and we may expose secondary
4595 optimization opportunities.
4597 This routine is effectively a driver for the generic jump
4598 threading code. It basically just presents the generic code
4599 with edges that may be suitable for jump threading.
4601 Unlike DOM, we do not iterate VRP if jump threading was successful.
4602 While iterating may expose new opportunities for VRP, it is expected
4603 those opportunities would be very limited and the compile time cost
4604 to expose those opportunities would be significant.
4606 As jump threading opportunities are discovered, they are registered
4607 for later realization. */
4610 identify_jump_threads (void)
4615 /* Ugh. When substituting values earlier in this pass we can
4616 wipe the dominance information. So rebuild the dominator
4617 information as we need it within the jump threading code. */
4618 calculate_dominance_info (CDI_DOMINATORS);
4620 /* We do not allow VRP information to be used for jump threading
4621 across a back edge in the CFG. Otherwise it becomes too
4622 difficult to avoid eliminating loop exit tests. Of course
4623 EDGE_DFS_BACK is not accurate at this time so we have to
4625 mark_dfs_back_edges ();
4627 /* Allocate our unwinder stack to unwind any temporary equivalences
4628 that might be recorded. */
4629 stack = VEC_alloc (tree, heap, 20);
4631 /* To avoid lots of silly node creation, we create a single
4632 conditional and just modify it in-place when attempting to
4634 dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL);
4635 dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL);
4637 /* Walk through all the blocks finding those which present a
4638 potential jump threading opportunity. We could set this up
4639 as a dominator walker and record data during the walk, but
4640 I doubt it's worth the effort for the classes of jump
4641 threading opportunities we are trying to identify at this
4642 point in compilation. */
4647 /* If the generic jump threading code does not find this block
4648 interesting, then there is nothing to do. */
4649 if (! potentially_threadable_block (bb))
4652 /* We only care about blocks ending in a COND_EXPR. While there
4653 may be some value in handling SWITCH_EXPR here, I doubt it's
4654 terribly important. */
4655 last = bsi_stmt (bsi_last (bb));
4656 if (TREE_CODE (last) != COND_EXPR)
4659 /* We're basically looking for any kind of conditional with
4660 integral type arguments. */
4661 cond = COND_EXPR_COND (last);
4662 if ((TREE_CODE (cond) == SSA_NAME
4663 && INTEGRAL_TYPE_P (TREE_TYPE (cond)))
4664 || (COMPARISON_CLASS_P (cond)
4665 && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
4666 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0)))
4667 && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME
4668 || is_gimple_min_invariant (TREE_OPERAND (cond, 1)))
4669 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
4674 /* We've got a block with multiple predecessors and multiple
4675 successors which also ends in a suitable conditional. For
4676 each predecessor, see if we can thread it to a specific
4678 FOR_EACH_EDGE (e, ei, bb->preds)
4680 /* Do not thread across back edges or abnormal edges
4682 if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
4685 thread_across_edge (dummy, e, true,
4687 simplify_stmt_for_jump_threading);
4692 /* We do not actually update the CFG or SSA graphs at this point as
4693 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
4694 handle ASSERT_EXPRs gracefully. */
4697 /* We identified all the jump threading opportunities earlier, but could
4698 not transform the CFG at that time. This routine transforms the
4699 CFG and arranges for the dominator tree to be rebuilt if necessary.
4701 Note the SSA graph update will occur during the normal TODO
4702 processing by the pass manager. */
4704 finalize_jump_threads (void)
4706 bool cfg_altered = false;
4707 cfg_altered = thread_through_all_blocks ();
4709 /* If we threaded jumps, then we need to recompute the dominance
4710 information, to safely do that we must clean up the CFG first. */
4713 free_dominance_info (CDI_DOMINATORS);
4714 cleanup_tree_cfg ();
4715 calculate_dominance_info (CDI_DOMINATORS);
4717 VEC_free (tree, heap, stack);
4721 /* Traverse all the blocks folding conditionals with known ranges. */
4727 prop_value_t *single_val_range;
4728 bool do_value_subst_p;
4732 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
4733 dump_all_value_ranges (dump_file);
4734 fprintf (dump_file, "\n");
4737 /* We may have ended with ranges that have exactly one value. Those
4738 values can be substituted as any other copy/const propagated
4739 value using substitute_and_fold. */
4740 single_val_range = XCNEWVEC (prop_value_t, num_ssa_names);
4742 do_value_subst_p = false;
4743 for (i = 0; i < num_ssa_names; i++)
4745 && vr_value[i]->type == VR_RANGE
4746 && vr_value[i]->min == vr_value[i]->max)
4748 single_val_range[i].value = vr_value[i]->min;
4749 do_value_subst_p = true;
4752 if (!do_value_subst_p)
4754 /* We found no single-valued ranges, don't waste time trying to
4755 do single value substitution in substitute_and_fold. */
4756 free (single_val_range);
4757 single_val_range = NULL;
4760 substitute_and_fold (single_val_range, true);
4762 /* We must identify jump threading opportunities before we release
4763 the datastructures built by VRP. */
4764 identify_jump_threads ();
4766 /* Free allocated memory. */
4767 for (i = 0; i < num_ssa_names; i++)
4770 BITMAP_FREE (vr_value[i]->equiv);
4774 free (single_val_range);
4777 /* So that we can distinguish between VRP data being available
4778 and not available. */
4783 /* Main entry point to VRP (Value Range Propagation). This pass is
4784 loosely based on J. R. C. Patterson, ``Accurate Static Branch
4785 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
4786 Programming Language Design and Implementation, pp. 67-78, 1995.
4787 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
4789 This is essentially an SSA-CCP pass modified to deal with ranges
4790 instead of constants.
4792 While propagating ranges, we may find that two or more SSA name
4793 have equivalent, though distinct ranges. For instance,
4796 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
4798 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
4802 In the code above, pointer p_5 has range [q_2, q_2], but from the
4803 code we can also determine that p_5 cannot be NULL and, if q_2 had
4804 a non-varying range, p_5's range should also be compatible with it.
4806 These equivalences are created by two expressions: ASSERT_EXPR and
4807 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
4808 result of another assertion, then we can use the fact that p_5 and
4809 p_4 are equivalent when evaluating p_5's range.
4811 Together with value ranges, we also propagate these equivalences
4812 between names so that we can take advantage of information from
4813 multiple ranges when doing final replacement. Note that this
4814 equivalency relation is transitive but not symmetric.
4816 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
4817 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
4818 in contexts where that assertion does not hold (e.g., in line 6).
4820 TODO, the main difference between this pass and Patterson's is that
4821 we do not propagate edge probabilities. We only compute whether
4822 edges can be taken or not. That is, instead of having a spectrum
4823 of jump probabilities between 0 and 1, we only deal with 0, 1 and
4824 DON'T KNOW. In the future, it may be worthwhile to propagate
4825 probabilities to aid branch prediction. */
4830 insert_range_assertions ();
4832 loop_optimizer_init (LOOPS_NORMAL);
4837 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
4843 loop_optimizer_finalize ();
4846 /* ASSERT_EXPRs must be removed before finalizing jump threads
4847 as finalizing jump threads calls the CFG cleanup code which
4848 does not properly handle ASSERT_EXPRs. */
4849 remove_range_assertions ();
4851 /* If we exposed any new variables, go ahead and put them into
4852 SSA form now, before we handle jump threading. This simplifies
4853 interactions between rewriting of _DECL nodes into SSA form
4854 and rewriting SSA_NAME nodes into SSA form after block
4855 duplication and CFG manipulation. */
4856 update_ssa (TODO_update_ssa);
4858 finalize_jump_threads ();
4865 return flag_tree_vrp != 0;
4868 struct tree_opt_pass pass_vrp =
4871 gate_vrp, /* gate */
4872 execute_vrp, /* execute */
4875 0, /* static_pass_number */
4876 TV_TREE_VRP, /* tv_id */
4877 PROP_ssa | PROP_alias, /* properties_required */
4878 0, /* properties_provided */
4879 0, /* properties_destroyed */
4880 0, /* todo_flags_start */
4886 | TODO_update_smt_usage, /* todo_flags_finish */