1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005, 2006, 2007 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"
38 #include "tree-scalar-evolution.h"
39 #include "tree-ssa-propagate.h"
40 #include "tree-chrec.h"
42 /* Set of SSA names found during the dominator traversal of a
43 sub-graph in find_assert_locations. */
44 static sbitmap found_in_subgraph;
46 /* Local functions. */
47 static int compare_values (tree val1, tree val2);
48 static int compare_values_warnv (tree val1, tree val2, bool *);
49 static void vrp_meet (value_range_t *, value_range_t *);
50 static tree vrp_evaluate_conditional_warnv (tree, bool, bool *);
52 /* Location information for ASSERT_EXPRs. Each instance of this
53 structure describes an ASSERT_EXPR for an SSA name. Since a single
54 SSA name may have more than one assertion associated with it, these
55 locations are kept in a linked list attached to the corresponding
59 /* Basic block where the assertion would be inserted. */
62 /* Some assertions need to be inserted on an edge (e.g., assertions
63 generated by COND_EXPRs). In those cases, BB will be NULL. */
66 /* Pointer to the statement that generated this assertion. */
67 block_stmt_iterator si;
69 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
70 enum tree_code comp_code;
72 /* Value being compared against. */
75 /* Next node in the linked list. */
76 struct assert_locus_d *next;
79 typedef struct assert_locus_d *assert_locus_t;
81 /* If bit I is present, it means that SSA name N_i has a list of
82 assertions that should be inserted in the IL. */
83 static bitmap need_assert_for;
85 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
86 holds a list of ASSERT_LOCUS_T nodes that describe where
87 ASSERT_EXPRs for SSA name N_I should be inserted. */
88 static assert_locus_t *asserts_for;
90 /* Set of blocks visited in find_assert_locations. Used to avoid
91 visiting the same block more than once. */
92 static sbitmap blocks_visited;
94 /* Value range array. After propagation, VR_VALUE[I] holds the range
95 of values that SSA name N_I may take. */
96 static value_range_t **vr_value;
99 /* Return whether TYPE should use an overflow infinity distinct from
100 TYPE_{MIN,MAX}_VALUE. We use an overflow infinity value to
101 represent a signed overflow during VRP computations. An infinity
102 is distinct from a half-range, which will go from some number to
103 TYPE_{MIN,MAX}_VALUE. */
106 needs_overflow_infinity (tree type)
108 return INTEGRAL_TYPE_P (type) && !TYPE_OVERFLOW_WRAPS (type);
111 /* Return whether TYPE can support our overflow infinity
112 representation: we use the TREE_OVERFLOW flag, which only exists
113 for constants. If TYPE doesn't support this, we don't optimize
114 cases which would require signed overflow--we drop them to
118 supports_overflow_infinity (tree type)
120 #ifdef ENABLE_CHECKING
121 gcc_assert (needs_overflow_infinity (type));
123 return (TYPE_MIN_VALUE (type) != NULL_TREE
124 && CONSTANT_CLASS_P (TYPE_MIN_VALUE (type))
125 && TYPE_MAX_VALUE (type) != NULL_TREE
126 && CONSTANT_CLASS_P (TYPE_MAX_VALUE (type)));
129 /* VAL is the maximum or minimum value of a type. Return a
130 corresponding overflow infinity. */
133 make_overflow_infinity (tree val)
135 #ifdef ENABLE_CHECKING
136 gcc_assert (val != NULL_TREE && CONSTANT_CLASS_P (val));
138 val = copy_node (val);
139 TREE_OVERFLOW (val) = 1;
143 /* Return a negative overflow infinity for TYPE. */
146 negative_overflow_infinity (tree type)
148 #ifdef ENABLE_CHECKING
149 gcc_assert (supports_overflow_infinity (type));
151 return make_overflow_infinity (TYPE_MIN_VALUE (type));
154 /* Return a positive overflow infinity for TYPE. */
157 positive_overflow_infinity (tree type)
159 #ifdef ENABLE_CHECKING
160 gcc_assert (supports_overflow_infinity (type));
162 return make_overflow_infinity (TYPE_MAX_VALUE (type));
165 /* Return whether VAL is a negative overflow infinity. */
168 is_negative_overflow_infinity (tree val)
170 return (needs_overflow_infinity (TREE_TYPE (val))
171 && CONSTANT_CLASS_P (val)
172 && TREE_OVERFLOW (val)
173 && operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0));
176 /* Return whether VAL is a positive overflow infinity. */
179 is_positive_overflow_infinity (tree val)
181 return (needs_overflow_infinity (TREE_TYPE (val))
182 && CONSTANT_CLASS_P (val)
183 && TREE_OVERFLOW (val)
184 && operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0));
187 /* Return whether VAL is a positive or negative overflow infinity. */
190 is_overflow_infinity (tree val)
192 return (needs_overflow_infinity (TREE_TYPE (val))
193 && CONSTANT_CLASS_P (val)
194 && TREE_OVERFLOW (val)
195 && (operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0)
196 || operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0)));
200 /* Return true if ARG is marked with the nonnull attribute in the
201 current function signature. */
204 nonnull_arg_p (tree arg)
206 tree t, attrs, fntype;
207 unsigned HOST_WIDE_INT arg_num;
209 gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
211 /* The static chain decl is always non null. */
212 if (arg == cfun->static_chain_decl)
215 fntype = TREE_TYPE (current_function_decl);
216 attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype));
218 /* If "nonnull" wasn't specified, we know nothing about the argument. */
219 if (attrs == NULL_TREE)
222 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
223 if (TREE_VALUE (attrs) == NULL_TREE)
226 /* Get the position number for ARG in the function signature. */
227 for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl);
229 t = TREE_CHAIN (t), arg_num++)
235 gcc_assert (t == arg);
237 /* Now see if ARG_NUM is mentioned in the nonnull list. */
238 for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
240 if (compare_tree_int (TREE_VALUE (t), arg_num) == 0)
248 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
251 set_value_range (value_range_t *vr, enum value_range_type t, tree min,
252 tree max, bitmap equiv)
254 #if defined ENABLE_CHECKING
255 /* Check the validity of the range. */
256 if (t == VR_RANGE || t == VR_ANTI_RANGE)
260 gcc_assert (min && max);
262 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
263 gcc_assert ((min != TYPE_MIN_VALUE (TREE_TYPE (min))
264 && !is_negative_overflow_infinity (min))
265 || (max != TYPE_MAX_VALUE (TREE_TYPE (max))
266 && !is_positive_overflow_infinity (max)));
268 cmp = compare_values (min, max);
269 gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
272 if (t == VR_UNDEFINED || t == VR_VARYING)
273 gcc_assert (min == NULL_TREE && max == NULL_TREE);
275 if (t == VR_UNDEFINED || t == VR_VARYING)
276 gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
283 /* Since updating the equivalence set involves deep copying the
284 bitmaps, only do it if absolutely necessary. */
285 if (vr->equiv == NULL)
286 vr->equiv = BITMAP_ALLOC (NULL);
288 if (equiv != vr->equiv)
290 if (equiv && !bitmap_empty_p (equiv))
291 bitmap_copy (vr->equiv, equiv);
293 bitmap_clear (vr->equiv);
298 /* Copy value range FROM into value range TO. */
301 copy_value_range (value_range_t *to, value_range_t *from)
303 set_value_range (to, from->type, from->min, from->max, from->equiv);
307 /* Set value range VR to VR_VARYING. */
310 set_value_range_to_varying (value_range_t *vr)
312 vr->type = VR_VARYING;
313 vr->min = vr->max = NULL_TREE;
315 bitmap_clear (vr->equiv);
318 /* Set value range VR to a non-negative range of type TYPE.
319 OVERFLOW_INFINITY indicates whether to use a overflow infinity
320 rather than TYPE_MAX_VALUE; this should be true if we determine
321 that the range is nonnegative based on the assumption that signed
322 overflow does not occur. */
325 set_value_range_to_nonnegative (value_range_t *vr, tree type,
326 bool overflow_infinity)
330 if (overflow_infinity && !supports_overflow_infinity (type))
332 set_value_range_to_varying (vr);
336 zero = build_int_cst (type, 0);
337 set_value_range (vr, VR_RANGE, zero,
339 ? positive_overflow_infinity (type)
340 : TYPE_MAX_VALUE (type)),
344 /* Set value range VR to a non-NULL range of type TYPE. */
347 set_value_range_to_nonnull (value_range_t *vr, tree type)
349 tree zero = build_int_cst (type, 0);
350 set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
354 /* Set value range VR to a NULL range of type TYPE. */
357 set_value_range_to_null (value_range_t *vr, tree type)
359 tree zero = build_int_cst (type, 0);
360 set_value_range (vr, VR_RANGE, zero, zero, vr->equiv);
364 /* Set value range VR to a range of a truthvalue of type TYPE. */
367 set_value_range_to_truthvalue (value_range_t *vr, tree type)
369 if (TYPE_PRECISION (type) == 1)
370 set_value_range_to_varying (vr);
372 set_value_range (vr, VR_RANGE,
373 build_int_cst (type, 0), build_int_cst (type, 1),
378 /* Set value range VR to VR_UNDEFINED. */
381 set_value_range_to_undefined (value_range_t *vr)
383 vr->type = VR_UNDEFINED;
384 vr->min = vr->max = NULL_TREE;
386 bitmap_clear (vr->equiv);
390 /* Return value range information for VAR.
392 If we have no values ranges recorded (ie, VRP is not running), then
393 return NULL. Otherwise create an empty range if none existed for VAR. */
395 static value_range_t *
396 get_value_range (tree var)
400 unsigned ver = SSA_NAME_VERSION (var);
402 /* If we have no recorded ranges, then return NULL. */
410 /* Create a default value range. */
411 vr_value[ver] = vr = XCNEW (value_range_t);
413 /* Allocate an equivalence set. */
414 vr->equiv = BITMAP_ALLOC (NULL);
416 /* If VAR is a default definition, the variable can take any value
418 sym = SSA_NAME_VAR (var);
419 if (SSA_NAME_IS_DEFAULT_DEF (var))
421 /* Try to use the "nonnull" attribute to create ~[0, 0]
422 anti-ranges for pointers. Note that this is only valid with
423 default definitions of PARM_DECLs. */
424 if (TREE_CODE (sym) == PARM_DECL
425 && POINTER_TYPE_P (TREE_TYPE (sym))
426 && nonnull_arg_p (sym))
427 set_value_range_to_nonnull (vr, TREE_TYPE (sym));
429 set_value_range_to_varying (vr);
435 /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */
438 vrp_operand_equal_p (tree val1, tree val2)
442 if (!val1 || !val2 || !operand_equal_p (val1, val2, 0))
444 if (is_overflow_infinity (val1))
445 return is_overflow_infinity (val2);
449 /* Return true, if the bitmaps B1 and B2 are equal. */
452 vrp_bitmap_equal_p (bitmap b1, bitmap b2)
456 && bitmap_equal_p (b1, b2)));
459 /* Update the value range and equivalence set for variable VAR to
460 NEW_VR. Return true if NEW_VR is different from VAR's previous
463 NOTE: This function assumes that NEW_VR is a temporary value range
464 object created for the sole purpose of updating VAR's range. The
465 storage used by the equivalence set from NEW_VR will be freed by
466 this function. Do not call update_value_range when NEW_VR
467 is the range object associated with another SSA name. */
470 update_value_range (tree var, value_range_t *new_vr)
472 value_range_t *old_vr;
475 /* Update the value range, if necessary. */
476 old_vr = get_value_range (var);
477 is_new = old_vr->type != new_vr->type
478 || !vrp_operand_equal_p (old_vr->min, new_vr->min)
479 || !vrp_operand_equal_p (old_vr->max, new_vr->max)
480 || !vrp_bitmap_equal_p (old_vr->equiv, new_vr->equiv);
483 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
486 BITMAP_FREE (new_vr->equiv);
487 new_vr->equiv = NULL;
493 /* Add VAR and VAR's equivalence set to EQUIV. */
496 add_equivalence (bitmap equiv, tree var)
498 unsigned ver = SSA_NAME_VERSION (var);
499 value_range_t *vr = vr_value[ver];
501 bitmap_set_bit (equiv, ver);
503 bitmap_ior_into (equiv, vr->equiv);
507 /* Return true if VR is ~[0, 0]. */
510 range_is_nonnull (value_range_t *vr)
512 return vr->type == VR_ANTI_RANGE
513 && integer_zerop (vr->min)
514 && integer_zerop (vr->max);
518 /* Return true if VR is [0, 0]. */
521 range_is_null (value_range_t *vr)
523 return vr->type == VR_RANGE
524 && integer_zerop (vr->min)
525 && integer_zerop (vr->max);
529 /* Return true if value range VR involves at least one symbol. */
532 symbolic_range_p (value_range_t *vr)
534 return (!is_gimple_min_invariant (vr->min)
535 || !is_gimple_min_invariant (vr->max));
538 /* Return true if value range VR uses a overflow infinity. */
541 overflow_infinity_range_p (value_range_t *vr)
543 return (vr->type == VR_RANGE
544 && (is_overflow_infinity (vr->min)
545 || is_overflow_infinity (vr->max)));
548 /* Return false if we can not make a valid comparison based on VR;
549 this will be the case if it uses an overflow infinity and overflow
550 is not undefined (i.e., -fno-strict-overflow is in effect).
551 Otherwise return true, and set *STRICT_OVERFLOW_P to true if VR
552 uses an overflow infinity. */
555 usable_range_p (value_range_t *vr, bool *strict_overflow_p)
557 gcc_assert (vr->type == VR_RANGE);
558 if (is_overflow_infinity (vr->min))
560 *strict_overflow_p = true;
561 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->min)))
564 if (is_overflow_infinity (vr->max))
566 *strict_overflow_p = true;
567 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->max)))
574 /* Like tree_expr_nonnegative_warnv_p, but this function uses value
575 ranges obtained so far. */
578 vrp_expr_computes_nonnegative (tree expr, bool *strict_overflow_p)
580 return tree_expr_nonnegative_warnv_p (expr, strict_overflow_p);
583 /* Like tree_expr_nonzero_warnv_p, but this function uses value ranges
587 vrp_expr_computes_nonzero (tree expr, bool *strict_overflow_p)
589 if (tree_expr_nonzero_warnv_p (expr, strict_overflow_p))
592 /* If we have an expression of the form &X->a, then the expression
593 is nonnull if X is nonnull. */
594 if (TREE_CODE (expr) == ADDR_EXPR)
596 tree base = get_base_address (TREE_OPERAND (expr, 0));
598 if (base != NULL_TREE
599 && TREE_CODE (base) == INDIRECT_REF
600 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
602 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
603 if (range_is_nonnull (vr))
611 /* Returns true if EXPR is a valid value (as expected by compare_values) --
612 a gimple invariant, or SSA_NAME +- CST. */
615 valid_value_p (tree expr)
617 if (TREE_CODE (expr) == SSA_NAME)
620 if (TREE_CODE (expr) == PLUS_EXPR
621 || TREE_CODE (expr) == MINUS_EXPR)
622 return (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME
623 && TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST);
625 return is_gimple_min_invariant (expr);
631 -2 if those are incomparable. */
633 operand_less_p (tree val, tree val2)
635 /* LT is folded faster than GE and others. Inline the common case. */
636 if (TREE_CODE (val) == INTEGER_CST && TREE_CODE (val2) == INTEGER_CST)
638 if (TYPE_UNSIGNED (TREE_TYPE (val)))
639 return INT_CST_LT_UNSIGNED (val, val2);
642 if (INT_CST_LT (val, val2))
650 tcmp = fold_binary_to_constant (LT_EXPR, boolean_type_node, val, val2);
654 if (!integer_zerop (tcmp))
658 /* val >= val2, not considering overflow infinity. */
659 if (is_negative_overflow_infinity (val))
660 return is_negative_overflow_infinity (val2) ? 0 : 1;
661 else if (is_positive_overflow_infinity (val2))
662 return is_positive_overflow_infinity (val) ? 0 : 1;
667 /* Compare two values VAL1 and VAL2. Return
669 -2 if VAL1 and VAL2 cannot be compared at compile-time,
672 +1 if VAL1 > VAL2, and
675 This is similar to tree_int_cst_compare but supports pointer values
676 and values that cannot be compared at compile time.
678 If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to
679 true if the return value is only valid if we assume that signed
680 overflow is undefined. */
683 compare_values_warnv (tree val1, tree val2, bool *strict_overflow_p)
688 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
690 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
691 == POINTER_TYPE_P (TREE_TYPE (val2)));
693 if ((TREE_CODE (val1) == SSA_NAME
694 || TREE_CODE (val1) == PLUS_EXPR
695 || TREE_CODE (val1) == MINUS_EXPR)
696 && (TREE_CODE (val2) == SSA_NAME
697 || TREE_CODE (val2) == PLUS_EXPR
698 || TREE_CODE (val2) == MINUS_EXPR))
701 enum tree_code code1, code2;
703 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
704 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
705 same name, return -2. */
706 if (TREE_CODE (val1) == SSA_NAME)
714 code1 = TREE_CODE (val1);
715 n1 = TREE_OPERAND (val1, 0);
716 c1 = TREE_OPERAND (val1, 1);
717 if (tree_int_cst_sgn (c1) == -1)
719 if (is_negative_overflow_infinity (c1))
721 c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1);
724 code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
728 if (TREE_CODE (val2) == SSA_NAME)
736 code2 = TREE_CODE (val2);
737 n2 = TREE_OPERAND (val2, 0);
738 c2 = TREE_OPERAND (val2, 1);
739 if (tree_int_cst_sgn (c2) == -1)
741 if (is_negative_overflow_infinity (c2))
743 c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2);
746 code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
750 /* Both values must use the same name. */
754 if (code1 == SSA_NAME
755 && code2 == SSA_NAME)
759 /* If overflow is defined we cannot simplify more. */
760 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1)))
763 if (strict_overflow_p != NULL)
764 *strict_overflow_p = true;
766 if (code1 == SSA_NAME)
768 if (code2 == PLUS_EXPR)
769 /* NAME < NAME + CST */
771 else if (code2 == MINUS_EXPR)
772 /* NAME > NAME - CST */
775 else if (code1 == PLUS_EXPR)
777 if (code2 == SSA_NAME)
778 /* NAME + CST > NAME */
780 else if (code2 == PLUS_EXPR)
781 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
782 return compare_values_warnv (c1, c2, strict_overflow_p);
783 else if (code2 == MINUS_EXPR)
784 /* NAME + CST1 > NAME - CST2 */
787 else if (code1 == MINUS_EXPR)
789 if (code2 == SSA_NAME)
790 /* NAME - CST < NAME */
792 else if (code2 == PLUS_EXPR)
793 /* NAME - CST1 < NAME + CST2 */
795 else if (code2 == MINUS_EXPR)
796 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
797 C1 and C2 are swapped in the call to compare_values. */
798 return compare_values_warnv (c2, c1, strict_overflow_p);
804 /* We cannot compare non-constants. */
805 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
808 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
810 /* We cannot compare overflowed values, except for overflow
812 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
814 if (strict_overflow_p != NULL)
815 *strict_overflow_p = true;
816 if (is_negative_overflow_infinity (val1))
817 return is_negative_overflow_infinity (val2) ? 0 : -1;
818 else if (is_negative_overflow_infinity (val2))
820 else if (is_positive_overflow_infinity (val1))
821 return is_positive_overflow_infinity (val2) ? 0 : 1;
822 else if (is_positive_overflow_infinity (val2))
827 return tree_int_cst_compare (val1, val2);
833 /* First see if VAL1 and VAL2 are not the same. */
834 if (val1 == val2 || operand_equal_p (val1, val2, 0))
837 /* If VAL1 is a lower address than VAL2, return -1. */
838 if (operand_less_p (val1, val2) == 1)
841 /* If VAL1 is a higher address than VAL2, return +1. */
842 if (operand_less_p (val2, val1) == 1)
845 /* If VAL1 is different than VAL2, return +2.
846 For integer constants we either have already returned -1 or 1
847 or they are equivalent. We still might succeed in proving
848 something about non-trivial operands. */
849 if (TREE_CODE (val1) != INTEGER_CST
850 || TREE_CODE (val2) != INTEGER_CST)
852 t = fold_binary_to_constant (NE_EXPR, boolean_type_node, val1, val2);
853 if (t && tree_expr_nonzero_p (t))
861 /* Compare values like compare_values_warnv, but treat comparisons of
862 nonconstants which rely on undefined overflow as incomparable. */
865 compare_values (tree val1, tree val2)
871 ret = compare_values_warnv (val1, val2, &sop);
873 && (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2)))
879 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
880 0 if VAL is not inside VR,
881 -2 if we cannot tell either way.
883 FIXME, the current semantics of this functions are a bit quirky
884 when taken in the context of VRP. In here we do not care
885 about VR's type. If VR is the anti-range ~[3, 5] the call
886 value_inside_range (4, VR) will return 1.
888 This is counter-intuitive in a strict sense, but the callers
889 currently expect this. They are calling the function
890 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
891 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
894 This also applies to value_ranges_intersect_p and
895 range_includes_zero_p. The semantics of VR_RANGE and
896 VR_ANTI_RANGE should be encoded here, but that also means
897 adapting the users of these functions to the new semantics.
899 Benchmark compile/20001226-1.c compilation time after changing this
903 value_inside_range (tree val, value_range_t * vr)
907 cmp1 = operand_less_p (val, vr->min);
913 cmp2 = operand_less_p (vr->max, val);
921 /* Return true if value ranges VR0 and VR1 have a non-empty
924 Benchmark compile/20001226-1.c compilation time after changing this
929 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
931 /* The value ranges do not intersect if the maximum of the first range is
932 less than the minimum of the second range or vice versa.
933 When those relations are unknown, we can't do any better. */
934 if (operand_less_p (vr0->max, vr1->min) != 0)
936 if (operand_less_p (vr1->max, vr0->min) != 0)
942 /* Return true if VR includes the value zero, false otherwise. FIXME,
943 currently this will return false for an anti-range like ~[-4, 3].
944 This will be wrong when the semantics of value_inside_range are
945 modified (currently the users of this function expect these
949 range_includes_zero_p (value_range_t *vr)
953 gcc_assert (vr->type != VR_UNDEFINED
954 && vr->type != VR_VARYING
955 && !symbolic_range_p (vr));
957 zero = build_int_cst (TREE_TYPE (vr->min), 0);
958 return (value_inside_range (zero, vr) == 1);
961 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
962 false otherwise or if no value range information is available. */
965 ssa_name_nonnegative_p (tree t)
967 value_range_t *vr = get_value_range (t);
972 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
973 which would return a useful value should be encoded as a VR_RANGE. */
974 if (vr->type == VR_RANGE)
976 int result = compare_values (vr->min, integer_zero_node);
978 return (result == 0 || result == 1);
983 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
984 false otherwise or if no value range information is available. */
987 ssa_name_nonzero_p (tree t)
989 value_range_t *vr = get_value_range (t);
994 /* A VR_RANGE which does not include zero is a nonzero value. */
995 if (vr->type == VR_RANGE && !symbolic_range_p (vr))
996 return ! range_includes_zero_p (vr);
998 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
999 if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr))
1000 return range_includes_zero_p (vr);
1006 /* Extract value range information from an ASSERT_EXPR EXPR and store
1010 extract_range_from_assert (value_range_t *vr_p, tree expr)
1012 tree var, cond, limit, min, max, type;
1013 value_range_t *var_vr, *limit_vr;
1014 enum tree_code cond_code;
1016 var = ASSERT_EXPR_VAR (expr);
1017 cond = ASSERT_EXPR_COND (expr);
1019 gcc_assert (COMPARISON_CLASS_P (cond));
1021 /* Find VAR in the ASSERT_EXPR conditional. */
1022 if (var == TREE_OPERAND (cond, 0))
1024 /* If the predicate is of the form VAR COMP LIMIT, then we just
1025 take LIMIT from the RHS and use the same comparison code. */
1026 limit = TREE_OPERAND (cond, 1);
1027 cond_code = TREE_CODE (cond);
1031 /* If the predicate is of the form LIMIT COMP VAR, then we need
1032 to flip around the comparison code to create the proper range
1034 limit = TREE_OPERAND (cond, 0);
1035 cond_code = swap_tree_comparison (TREE_CODE (cond));
1038 type = TREE_TYPE (limit);
1039 gcc_assert (limit != var);
1041 /* For pointer arithmetic, we only keep track of pointer equality
1043 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
1045 set_value_range_to_varying (vr_p);
1049 /* If LIMIT is another SSA name and LIMIT has a range of its own,
1050 try to use LIMIT's range to avoid creating symbolic ranges
1052 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
1054 /* LIMIT's range is only interesting if it has any useful information. */
1056 && (limit_vr->type == VR_UNDEFINED
1057 || limit_vr->type == VR_VARYING
1058 || symbolic_range_p (limit_vr)))
1061 /* Initially, the new range has the same set of equivalences of
1062 VAR's range. This will be revised before returning the final
1063 value. Since assertions may be chained via mutually exclusive
1064 predicates, we will need to trim the set of equivalences before
1066 gcc_assert (vr_p->equiv == NULL);
1067 vr_p->equiv = BITMAP_ALLOC (NULL);
1068 add_equivalence (vr_p->equiv, var);
1070 /* Extract a new range based on the asserted comparison for VAR and
1071 LIMIT's value range. Notice that if LIMIT has an anti-range, we
1072 will only use it for equality comparisons (EQ_EXPR). For any
1073 other kind of assertion, we cannot derive a range from LIMIT's
1074 anti-range that can be used to describe the new range. For
1075 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
1076 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
1077 no single range for x_2 that could describe LE_EXPR, so we might
1078 as well build the range [b_4, +INF] for it. */
1079 if (cond_code == EQ_EXPR)
1081 enum value_range_type range_type;
1085 range_type = limit_vr->type;
1086 min = limit_vr->min;
1087 max = limit_vr->max;
1091 range_type = VR_RANGE;
1096 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
1098 /* When asserting the equality VAR == LIMIT and LIMIT is another
1099 SSA name, the new range will also inherit the equivalence set
1101 if (TREE_CODE (limit) == SSA_NAME)
1102 add_equivalence (vr_p->equiv, limit);
1104 else if (cond_code == NE_EXPR)
1106 /* As described above, when LIMIT's range is an anti-range and
1107 this assertion is an inequality (NE_EXPR), then we cannot
1108 derive anything from the anti-range. For instance, if
1109 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
1110 not imply that VAR's range is [0, 0]. So, in the case of
1111 anti-ranges, we just assert the inequality using LIMIT and
1114 If LIMIT_VR is a range, we can only use it to build a new
1115 anti-range if LIMIT_VR is a single-valued range. For
1116 instance, if LIMIT_VR is [0, 1], the predicate
1117 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
1118 Rather, it means that for value 0 VAR should be ~[0, 0]
1119 and for value 1, VAR should be ~[1, 1]. We cannot
1120 represent these ranges.
1122 The only situation in which we can build a valid
1123 anti-range is when LIMIT_VR is a single-valued range
1124 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
1125 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
1127 && limit_vr->type == VR_RANGE
1128 && compare_values (limit_vr->min, limit_vr->max) == 0)
1130 min = limit_vr->min;
1131 max = limit_vr->max;
1135 /* In any other case, we cannot use LIMIT's range to build a
1136 valid anti-range. */
1140 /* If MIN and MAX cover the whole range for their type, then
1141 just use the original LIMIT. */
1142 if (INTEGRAL_TYPE_P (type)
1143 && (min == TYPE_MIN_VALUE (type)
1144 || is_negative_overflow_infinity (min))
1145 && (max == TYPE_MAX_VALUE (type)
1146 || is_positive_overflow_infinity (max)))
1149 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
1151 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
1153 min = TYPE_MIN_VALUE (type);
1155 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
1159 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1160 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
1162 max = limit_vr->max;
1165 /* If the maximum value forces us to be out of bounds, simply punt.
1166 It would be pointless to try and do anything more since this
1167 all should be optimized away above us. */
1168 if ((cond_code == LT_EXPR
1169 && compare_values (max, min) == 0)
1170 || is_overflow_infinity (max))
1171 set_value_range_to_varying (vr_p);
1174 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
1175 if (cond_code == LT_EXPR)
1177 tree one = build_int_cst (type, 1);
1178 max = fold_build2 (MINUS_EXPR, type, max, one);
1181 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1184 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
1186 max = TYPE_MAX_VALUE (type);
1188 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
1192 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1193 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
1195 min = limit_vr->min;
1198 /* If the minimum value forces us to be out of bounds, simply punt.
1199 It would be pointless to try and do anything more since this
1200 all should be optimized away above us. */
1201 if ((cond_code == GT_EXPR
1202 && compare_values (min, max) == 0)
1203 || is_overflow_infinity (min))
1204 set_value_range_to_varying (vr_p);
1207 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
1208 if (cond_code == GT_EXPR)
1210 tree one = build_int_cst (type, 1);
1211 min = fold_build2 (PLUS_EXPR, type, min, one);
1214 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1220 /* If VAR already had a known range, it may happen that the new
1221 range we have computed and VAR's range are not compatible. For
1225 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
1227 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
1229 While the above comes from a faulty program, it will cause an ICE
1230 later because p_8 and p_6 will have incompatible ranges and at
1231 the same time will be considered equivalent. A similar situation
1235 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
1237 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
1239 Again i_6 and i_7 will have incompatible ranges. It would be
1240 pointless to try and do anything with i_7's range because
1241 anything dominated by 'if (i_5 < 5)' will be optimized away.
1242 Note, due to the wa in which simulation proceeds, the statement
1243 i_7 = ASSERT_EXPR <...> we would never be visited because the
1244 conditional 'if (i_5 < 5)' always evaluates to false. However,
1245 this extra check does not hurt and may protect against future
1246 changes to VRP that may get into a situation similar to the
1247 NULL pointer dereference example.
1249 Note that these compatibility tests are only needed when dealing
1250 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1251 are both anti-ranges, they will always be compatible, because two
1252 anti-ranges will always have a non-empty intersection. */
1254 var_vr = get_value_range (var);
1256 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1257 ranges or anti-ranges. */
1258 if (vr_p->type == VR_VARYING
1259 || vr_p->type == VR_UNDEFINED
1260 || var_vr->type == VR_VARYING
1261 || var_vr->type == VR_UNDEFINED
1262 || symbolic_range_p (vr_p)
1263 || symbolic_range_p (var_vr))
1266 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
1268 /* If the two ranges have a non-empty intersection, we can
1269 refine the resulting range. Since the assert expression
1270 creates an equivalency and at the same time it asserts a
1271 predicate, we can take the intersection of the two ranges to
1272 get better precision. */
1273 if (value_ranges_intersect_p (var_vr, vr_p))
1275 /* Use the larger of the two minimums. */
1276 if (compare_values (vr_p->min, var_vr->min) == -1)
1281 /* Use the smaller of the two maximums. */
1282 if (compare_values (vr_p->max, var_vr->max) == 1)
1287 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
1291 /* The two ranges do not intersect, set the new range to
1292 VARYING, because we will not be able to do anything
1293 meaningful with it. */
1294 set_value_range_to_varying (vr_p);
1297 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
1298 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
1300 /* A range and an anti-range will cancel each other only if
1301 their ends are the same. For instance, in the example above,
1302 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1303 so VR_P should be set to VR_VARYING. */
1304 if (compare_values (var_vr->min, vr_p->min) == 0
1305 && compare_values (var_vr->max, vr_p->max) == 0)
1306 set_value_range_to_varying (vr_p);
1309 tree min, max, anti_min, anti_max, real_min, real_max;
1312 /* We want to compute the logical AND of the two ranges;
1313 there are three cases to consider.
1316 1. The VR_ANTI_RANGE range is completely within the
1317 VR_RANGE and the endpoints of the ranges are
1318 different. In that case the resulting range
1319 should be whichever range is more precise.
1320 Typically that will be the VR_RANGE.
1322 2. The VR_ANTI_RANGE is completely disjoint from
1323 the VR_RANGE. In this case the resulting range
1324 should be the VR_RANGE.
1326 3. There is some overlap between the VR_ANTI_RANGE
1329 3a. If the high limit of the VR_ANTI_RANGE resides
1330 within the VR_RANGE, then the result is a new
1331 VR_RANGE starting at the high limit of the
1332 the VR_ANTI_RANGE + 1 and extending to the
1333 high limit of the original VR_RANGE.
1335 3b. If the low limit of the VR_ANTI_RANGE resides
1336 within the VR_RANGE, then the result is a new
1337 VR_RANGE starting at the low limit of the original
1338 VR_RANGE and extending to the low limit of the
1339 VR_ANTI_RANGE - 1. */
1340 if (vr_p->type == VR_ANTI_RANGE)
1342 anti_min = vr_p->min;
1343 anti_max = vr_p->max;
1344 real_min = var_vr->min;
1345 real_max = var_vr->max;
1349 anti_min = var_vr->min;
1350 anti_max = var_vr->max;
1351 real_min = vr_p->min;
1352 real_max = vr_p->max;
1356 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1357 not including any endpoints. */
1358 if (compare_values (anti_max, real_max) == -1
1359 && compare_values (anti_min, real_min) == 1)
1361 set_value_range (vr_p, VR_RANGE, real_min,
1362 real_max, vr_p->equiv);
1364 /* Case 2, VR_ANTI_RANGE completely disjoint from
1366 else if (compare_values (anti_min, real_max) == 1
1367 || compare_values (anti_max, real_min) == -1)
1369 set_value_range (vr_p, VR_RANGE, real_min,
1370 real_max, vr_p->equiv);
1372 /* Case 3a, the anti-range extends into the low
1373 part of the real range. Thus creating a new
1374 low for the real range. */
1375 else if (((cmp = compare_values (anti_max, real_min)) == 1
1377 && compare_values (anti_max, real_max) == -1)
1379 gcc_assert (!is_positive_overflow_infinity (anti_max));
1380 if (needs_overflow_infinity (TREE_TYPE (anti_max))
1381 && anti_max == TYPE_MAX_VALUE (TREE_TYPE (anti_max)))
1383 if (!supports_overflow_infinity (TREE_TYPE (var_vr->min)))
1385 set_value_range_to_varying (vr_p);
1388 min = positive_overflow_infinity (TREE_TYPE (var_vr->min));
1391 min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min),
1393 build_int_cst (TREE_TYPE (var_vr->min), 1));
1395 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1397 /* Case 3b, the anti-range extends into the high
1398 part of the real range. Thus creating a new
1399 higher for the real range. */
1400 else if (compare_values (anti_min, real_min) == 1
1401 && ((cmp = compare_values (anti_min, real_max)) == -1
1404 gcc_assert (!is_negative_overflow_infinity (anti_min));
1405 if (needs_overflow_infinity (TREE_TYPE (anti_min))
1406 && anti_min == TYPE_MIN_VALUE (TREE_TYPE (anti_min)))
1408 if (!supports_overflow_infinity (TREE_TYPE (var_vr->min)))
1410 set_value_range_to_varying (vr_p);
1413 max = negative_overflow_infinity (TREE_TYPE (var_vr->min));
1416 max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min),
1418 build_int_cst (TREE_TYPE (var_vr->min), 1));
1420 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1427 /* Extract range information from SSA name VAR and store it in VR. If
1428 VAR has an interesting range, use it. Otherwise, create the
1429 range [VAR, VAR] and return it. This is useful in situations where
1430 we may have conditionals testing values of VARYING names. For
1437 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1441 extract_range_from_ssa_name (value_range_t *vr, tree var)
1443 value_range_t *var_vr = get_value_range (var);
1445 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
1446 copy_value_range (vr, var_vr);
1448 set_value_range (vr, VR_RANGE, var, var, NULL);
1450 add_equivalence (vr->equiv, var);
1454 /* Wrapper around int_const_binop. If the operation overflows and we
1455 are not using wrapping arithmetic, then adjust the result to be
1456 -INF or +INF depending on CODE, VAL1 and VAL2. This can return
1457 NULL_TREE if we need to use an overflow infinity representation but
1458 the type does not support it. */
1461 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
1465 res = int_const_binop (code, val1, val2, 0);
1467 /* If we are not using wrapping arithmetic, operate symbolically
1468 on -INF and +INF. */
1469 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1)))
1471 int checkz = compare_values (res, val1);
1472 bool overflow = false;
1474 /* Ensure that res = val1 [+*] val2 >= val1
1475 or that res = val1 - val2 <= val1. */
1476 if ((code == PLUS_EXPR
1477 && !(checkz == 1 || checkz == 0))
1478 || (code == MINUS_EXPR
1479 && !(checkz == 0 || checkz == -1)))
1483 /* Checking for multiplication overflow is done by dividing the
1484 output of the multiplication by the first input of the
1485 multiplication. If the result of that division operation is
1486 not equal to the second input of the multiplication, then the
1487 multiplication overflowed. */
1488 else if (code == MULT_EXPR && !integer_zerop (val1))
1490 tree tmp = int_const_binop (TRUNC_DIV_EXPR,
1493 int check = compare_values (tmp, val2);
1501 res = copy_node (res);
1502 TREE_OVERFLOW (res) = 1;
1506 else if ((TREE_OVERFLOW (res)
1507 && !TREE_OVERFLOW (val1)
1508 && !TREE_OVERFLOW (val2))
1509 || is_overflow_infinity (val1)
1510 || is_overflow_infinity (val2))
1512 /* If the operation overflowed but neither VAL1 nor VAL2 are
1513 overflown, return -INF or +INF depending on the operation
1514 and the combination of signs of the operands. */
1515 int sgn1 = tree_int_cst_sgn (val1);
1516 int sgn2 = tree_int_cst_sgn (val2);
1518 if (needs_overflow_infinity (TREE_TYPE (res))
1519 && !supports_overflow_infinity (TREE_TYPE (res)))
1522 /* We have to punt on subtracting infinities of the same sign,
1523 since we can't tell what the sign of the result should
1525 if (code == MINUS_EXPR
1527 && is_overflow_infinity (val1)
1528 && is_overflow_infinity (val2))
1531 /* Notice that we only need to handle the restricted set of
1532 operations handled by extract_range_from_binary_expr.
1533 Among them, only multiplication, addition and subtraction
1534 can yield overflow without overflown operands because we
1535 are working with integral types only... except in the
1536 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1537 for division too. */
1539 /* For multiplication, the sign of the overflow is given
1540 by the comparison of the signs of the operands. */
1541 if ((code == MULT_EXPR && sgn1 == sgn2)
1542 /* For addition, the operands must be of the same sign
1543 to yield an overflow. Its sign is therefore that
1544 of one of the operands, for example the first. */
1545 || (code == PLUS_EXPR && sgn1 > 0)
1546 /* For subtraction, non-infinite operands must be of
1547 different signs to yield an overflow. Its sign is
1548 therefore that of the first operand or the opposite of
1549 that of the second operand. A first operand of 0 counts
1550 as positive here, for the corner case 0 - (-INF), which
1551 overflows, but must yield +INF. For infinite operands 0
1552 - INF is negative, not positive. */
1553 || (code == MINUS_EXPR
1555 ? !is_positive_overflow_infinity (val2)
1556 : is_negative_overflow_infinity (val2)))
1557 /* For division, the only case is -INF / -1 = +INF. */
1558 || code == TRUNC_DIV_EXPR
1559 || code == FLOOR_DIV_EXPR
1560 || code == CEIL_DIV_EXPR
1561 || code == EXACT_DIV_EXPR
1562 || code == ROUND_DIV_EXPR)
1563 return (needs_overflow_infinity (TREE_TYPE (res))
1564 ? positive_overflow_infinity (TREE_TYPE (res))
1565 : TYPE_MAX_VALUE (TREE_TYPE (res)));
1567 return (needs_overflow_infinity (TREE_TYPE (res))
1568 ? negative_overflow_infinity (TREE_TYPE (res))
1569 : TYPE_MIN_VALUE (TREE_TYPE (res)));
1576 /* Extract range information from a binary expression EXPR based on
1577 the ranges of each of its operands and the expression code. */
1580 extract_range_from_binary_expr (value_range_t *vr, tree expr)
1582 enum tree_code code = TREE_CODE (expr);
1583 enum value_range_type type;
1584 tree op0, op1, min, max;
1586 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1587 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1589 /* Not all binary expressions can be applied to ranges in a
1590 meaningful way. Handle only arithmetic operations. */
1591 if (code != PLUS_EXPR
1592 && code != MINUS_EXPR
1593 && code != MULT_EXPR
1594 && code != TRUNC_DIV_EXPR
1595 && code != FLOOR_DIV_EXPR
1596 && code != CEIL_DIV_EXPR
1597 && code != EXACT_DIV_EXPR
1598 && code != ROUND_DIV_EXPR
1601 && code != BIT_AND_EXPR
1602 && code != TRUTH_ANDIF_EXPR
1603 && code != TRUTH_ORIF_EXPR
1604 && code != TRUTH_AND_EXPR
1605 && code != TRUTH_OR_EXPR)
1607 set_value_range_to_varying (vr);
1611 /* Get value ranges for each operand. For constant operands, create
1612 a new value range with the operand to simplify processing. */
1613 op0 = TREE_OPERAND (expr, 0);
1614 if (TREE_CODE (op0) == SSA_NAME)
1615 vr0 = *(get_value_range (op0));
1616 else if (is_gimple_min_invariant (op0))
1617 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1619 set_value_range_to_varying (&vr0);
1621 op1 = TREE_OPERAND (expr, 1);
1622 if (TREE_CODE (op1) == SSA_NAME)
1623 vr1 = *(get_value_range (op1));
1624 else if (is_gimple_min_invariant (op1))
1625 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1627 set_value_range_to_varying (&vr1);
1629 /* If either range is UNDEFINED, so is the result. */
1630 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1632 set_value_range_to_undefined (vr);
1636 /* The type of the resulting value range defaults to VR0.TYPE. */
1639 /* Refuse to operate on VARYING ranges, ranges of different kinds
1640 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1641 because we may be able to derive a useful range even if one of
1642 the operands is VR_VARYING or symbolic range. TODO, we may be
1643 able to derive anti-ranges in some cases. */
1644 if (code != BIT_AND_EXPR
1645 && code != TRUTH_AND_EXPR
1646 && code != TRUTH_OR_EXPR
1647 && (vr0.type == VR_VARYING
1648 || vr1.type == VR_VARYING
1649 || vr0.type != vr1.type
1650 || symbolic_range_p (&vr0)
1651 || symbolic_range_p (&vr1)))
1653 set_value_range_to_varying (vr);
1657 /* Now evaluate the expression to determine the new range. */
1658 if (POINTER_TYPE_P (TREE_TYPE (expr))
1659 || POINTER_TYPE_P (TREE_TYPE (op0))
1660 || POINTER_TYPE_P (TREE_TYPE (op1)))
1662 /* For pointer types, we are really only interested in asserting
1663 whether the expression evaluates to non-NULL. FIXME, we used
1664 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1665 ivopts is generating expressions with pointer multiplication
1667 if (code == PLUS_EXPR)
1669 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1670 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1671 else if (range_is_null (&vr0) && range_is_null (&vr1))
1672 set_value_range_to_null (vr, TREE_TYPE (expr));
1674 set_value_range_to_varying (vr);
1678 /* Subtracting from a pointer, may yield 0, so just drop the
1679 resulting range to varying. */
1680 set_value_range_to_varying (vr);
1686 /* For integer ranges, apply the operation to each end of the
1687 range and see what we end up with. */
1688 if (code == TRUTH_ANDIF_EXPR
1689 || code == TRUTH_ORIF_EXPR
1690 || code == TRUTH_AND_EXPR
1691 || code == TRUTH_OR_EXPR)
1693 /* If one of the operands is zero, we know that the whole
1694 expression evaluates zero. */
1695 if (code == TRUTH_AND_EXPR
1696 && ((vr0.type == VR_RANGE
1697 && integer_zerop (vr0.min)
1698 && integer_zerop (vr0.max))
1699 || (vr1.type == VR_RANGE
1700 && integer_zerop (vr1.min)
1701 && integer_zerop (vr1.max))))
1704 min = max = build_int_cst (TREE_TYPE (expr), 0);
1706 /* If one of the operands is one, we know that the whole
1707 expression evaluates one. */
1708 else if (code == TRUTH_OR_EXPR
1709 && ((vr0.type == VR_RANGE
1710 && integer_onep (vr0.min)
1711 && integer_onep (vr0.max))
1712 || (vr1.type == VR_RANGE
1713 && integer_onep (vr1.min)
1714 && integer_onep (vr1.max))))
1717 min = max = build_int_cst (TREE_TYPE (expr), 1);
1719 else if (vr0.type != VR_VARYING
1720 && vr1.type != VR_VARYING
1721 && vr0.type == vr1.type
1722 && !symbolic_range_p (&vr0)
1723 && !overflow_infinity_range_p (&vr0)
1724 && !symbolic_range_p (&vr1)
1725 && !overflow_infinity_range_p (&vr1))
1727 /* Boolean expressions cannot be folded with int_const_binop. */
1728 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1729 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1733 /* The result of a TRUTH_*_EXPR is always true or false. */
1734 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
1738 else if (code == PLUS_EXPR
1740 || code == MAX_EXPR)
1742 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1743 VR_VARYING. It would take more effort to compute a precise
1744 range for such a case. For example, if we have op0 == 1 and
1745 op1 == -1 with their ranges both being ~[0,0], we would have
1746 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1747 Note that we are guaranteed to have vr0.type == vr1.type at
1749 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1751 set_value_range_to_varying (vr);
1755 /* For operations that make the resulting range directly
1756 proportional to the original ranges, apply the operation to
1757 the same end of each range. */
1758 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1759 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1761 else if (code == MULT_EXPR
1762 || code == TRUNC_DIV_EXPR
1763 || code == FLOOR_DIV_EXPR
1764 || code == CEIL_DIV_EXPR
1765 || code == EXACT_DIV_EXPR
1766 || code == ROUND_DIV_EXPR)
1772 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1773 drop to VR_VARYING. It would take more effort to compute a
1774 precise range for such a case. For example, if we have
1775 op0 == 65536 and op1 == 65536 with their ranges both being
1776 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1777 we cannot claim that the product is in ~[0,0]. Note that we
1778 are guaranteed to have vr0.type == vr1.type at this
1780 if (code == MULT_EXPR
1781 && vr0.type == VR_ANTI_RANGE
1782 && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0)))
1784 set_value_range_to_varying (vr);
1788 /* Multiplications and divisions are a bit tricky to handle,
1789 depending on the mix of signs we have in the two ranges, we
1790 need to operate on different values to get the minimum and
1791 maximum values for the new range. One approach is to figure
1792 out all the variations of range combinations and do the
1795 However, this involves several calls to compare_values and it
1796 is pretty convoluted. It's simpler to do the 4 operations
1797 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1798 MAX1) and then figure the smallest and largest values to form
1801 /* Divisions by zero result in a VARYING value. */
1802 if (code != MULT_EXPR
1803 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1805 set_value_range_to_varying (vr);
1809 /* Compute the 4 cross operations. */
1811 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1812 if (val[0] == NULL_TREE)
1815 if (vr1.max == vr1.min)
1819 val[1] = vrp_int_const_binop (code, vr0.min, vr1.max);
1820 if (val[1] == NULL_TREE)
1824 if (vr0.max == vr0.min)
1828 val[2] = vrp_int_const_binop (code, vr0.max, vr1.min);
1829 if (val[2] == NULL_TREE)
1833 if (vr0.min == vr0.max || vr1.min == vr1.max)
1837 val[3] = vrp_int_const_binop (code, vr0.max, vr1.max);
1838 if (val[3] == NULL_TREE)
1844 set_value_range_to_varying (vr);
1848 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1852 for (i = 1; i < 4; i++)
1854 if (!is_gimple_min_invariant (min)
1855 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
1856 || !is_gimple_min_invariant (max)
1857 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
1862 if (!is_gimple_min_invariant (val[i])
1863 || (TREE_OVERFLOW (val[i])
1864 && !is_overflow_infinity (val[i])))
1866 /* If we found an overflowed value, set MIN and MAX
1867 to it so that we set the resulting range to
1873 if (compare_values (val[i], min) == -1)
1876 if (compare_values (val[i], max) == 1)
1881 else if (code == MINUS_EXPR)
1883 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1884 VR_VARYING. It would take more effort to compute a precise
1885 range for such a case. For example, if we have op0 == 1 and
1886 op1 == 1 with their ranges both being ~[0,0], we would have
1887 op0 - op1 == 0, so we cannot claim that the difference is in
1888 ~[0,0]. Note that we are guaranteed to have
1889 vr0.type == vr1.type at this point. */
1890 if (vr0.type == VR_ANTI_RANGE)
1892 set_value_range_to_varying (vr);
1896 /* For MINUS_EXPR, apply the operation to the opposite ends of
1898 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1899 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1901 else if (code == BIT_AND_EXPR)
1903 if (vr0.type == VR_RANGE
1904 && vr0.min == vr0.max
1905 && TREE_CODE (vr0.max) == INTEGER_CST
1906 && !TREE_OVERFLOW (vr0.max)
1907 && tree_int_cst_sgn (vr0.max) >= 0)
1909 min = build_int_cst (TREE_TYPE (expr), 0);
1912 else if (vr1.type == VR_RANGE
1913 && vr1.min == vr1.max
1914 && TREE_CODE (vr1.max) == INTEGER_CST
1915 && !TREE_OVERFLOW (vr1.max)
1916 && tree_int_cst_sgn (vr1.max) >= 0)
1919 min = build_int_cst (TREE_TYPE (expr), 0);
1924 set_value_range_to_varying (vr);
1931 /* If either MIN or MAX overflowed, then set the resulting range to
1932 VARYING. But we do accept an overflow infinity
1934 if (min == NULL_TREE
1935 || !is_gimple_min_invariant (min)
1936 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
1938 || !is_gimple_min_invariant (max)
1939 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
1941 set_value_range_to_varying (vr);
1945 if ((min == TYPE_MIN_VALUE (TREE_TYPE (min))
1946 || is_negative_overflow_infinity (min))
1947 && (max == TYPE_MAX_VALUE (TREE_TYPE (max))
1948 || is_positive_overflow_infinity (max)))
1950 set_value_range_to_varying (vr);
1954 cmp = compare_values (min, max);
1955 if (cmp == -2 || cmp == 1)
1957 /* If the new range has its limits swapped around (MIN > MAX),
1958 then the operation caused one of them to wrap around, mark
1959 the new range VARYING. */
1960 set_value_range_to_varying (vr);
1963 set_value_range (vr, type, min, max, NULL);
1967 /* Extract range information from a unary expression EXPR based on
1968 the range of its operand and the expression code. */
1971 extract_range_from_unary_expr (value_range_t *vr, tree expr)
1973 enum tree_code code = TREE_CODE (expr);
1976 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1978 /* Refuse to operate on certain unary expressions for which we
1979 cannot easily determine a resulting range. */
1980 if (code == FIX_TRUNC_EXPR
1981 || code == FLOAT_EXPR
1982 || code == BIT_NOT_EXPR
1983 || code == NON_LVALUE_EXPR
1984 || code == CONJ_EXPR)
1986 set_value_range_to_varying (vr);
1990 /* Get value ranges for the operand. For constant operands, create
1991 a new value range with the operand to simplify processing. */
1992 op0 = TREE_OPERAND (expr, 0);
1993 if (TREE_CODE (op0) == SSA_NAME)
1994 vr0 = *(get_value_range (op0));
1995 else if (is_gimple_min_invariant (op0))
1996 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1998 set_value_range_to_varying (&vr0);
2000 /* If VR0 is UNDEFINED, so is the result. */
2001 if (vr0.type == VR_UNDEFINED)
2003 set_value_range_to_undefined (vr);
2007 /* Refuse to operate on symbolic ranges, or if neither operand is
2008 a pointer or integral type. */
2009 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0))
2010 && !POINTER_TYPE_P (TREE_TYPE (op0)))
2011 || (vr0.type != VR_VARYING
2012 && symbolic_range_p (&vr0)))
2014 set_value_range_to_varying (vr);
2018 /* If the expression involves pointers, we are only interested in
2019 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
2020 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
2025 if (range_is_nonnull (&vr0)
2026 || (tree_expr_nonzero_warnv_p (expr, &sop)
2028 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
2029 else if (range_is_null (&vr0))
2030 set_value_range_to_null (vr, TREE_TYPE (expr));
2032 set_value_range_to_varying (vr);
2037 /* Handle unary expressions on integer ranges. */
2038 if (code == NOP_EXPR || code == CONVERT_EXPR)
2040 tree inner_type = TREE_TYPE (op0);
2041 tree outer_type = TREE_TYPE (expr);
2043 /* If VR0 represents a simple range, then try to convert
2044 the min and max values for the range to the same type
2045 as OUTER_TYPE. If the results compare equal to VR0's
2046 min and max values and the new min is still less than
2047 or equal to the new max, then we can safely use the newly
2048 computed range for EXPR. This allows us to compute
2049 accurate ranges through many casts. */
2050 if ((vr0.type == VR_RANGE
2051 && !overflow_infinity_range_p (&vr0))
2052 || (vr0.type == VR_VARYING
2053 && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type)))
2055 tree new_min, new_max, orig_min, orig_max;
2057 /* Convert the input operand min/max to OUTER_TYPE. If
2058 the input has no range information, then use the min/max
2059 for the input's type. */
2060 if (vr0.type == VR_RANGE)
2067 orig_min = TYPE_MIN_VALUE (inner_type);
2068 orig_max = TYPE_MAX_VALUE (inner_type);
2071 new_min = fold_convert (outer_type, orig_min);
2072 new_max = fold_convert (outer_type, orig_max);
2074 /* Verify the new min/max values are gimple values and
2075 that they compare equal to the original input's
2077 if (is_gimple_val (new_min)
2078 && is_gimple_val (new_max)
2079 && tree_int_cst_equal (new_min, orig_min)
2080 && tree_int_cst_equal (new_max, orig_max)
2081 && (cmp = compare_values (new_min, new_max)) <= 0
2084 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
2089 /* When converting types of different sizes, set the result to
2090 VARYING. Things like sign extensions and precision loss may
2091 change the range. For instance, if x_3 is of type 'long long
2092 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
2093 is impossible to know at compile time whether y_5 will be
2095 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
2096 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
2098 set_value_range_to_varying (vr);
2103 /* Conversion of a VR_VARYING value to a wider type can result
2104 in a usable range. So wait until after we've handled conversions
2105 before dropping the result to VR_VARYING if we had a source
2106 operand that is VR_VARYING. */
2107 if (vr0.type == VR_VARYING)
2109 set_value_range_to_varying (vr);
2113 /* Apply the operation to each end of the range and see what we end
2115 if (code == NEGATE_EXPR
2116 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
2118 /* NEGATE_EXPR flips the range around. We need to treat
2119 TYPE_MIN_VALUE specially. */
2120 if (is_positive_overflow_infinity (vr0.max))
2121 min = negative_overflow_infinity (TREE_TYPE (expr));
2122 else if (is_negative_overflow_infinity (vr0.max))
2123 min = positive_overflow_infinity (TREE_TYPE (expr));
2124 else if (vr0.max != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2125 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2126 else if (needs_overflow_infinity (TREE_TYPE (expr)))
2128 if (supports_overflow_infinity (TREE_TYPE (expr)))
2129 min = positive_overflow_infinity (TREE_TYPE (expr));
2132 set_value_range_to_varying (vr);
2137 min = TYPE_MIN_VALUE (TREE_TYPE (expr));
2139 if (is_positive_overflow_infinity (vr0.min))
2140 max = negative_overflow_infinity (TREE_TYPE (expr));
2141 else if (is_negative_overflow_infinity (vr0.min))
2142 max = positive_overflow_infinity (TREE_TYPE (expr));
2143 else if (vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2144 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2145 else if (needs_overflow_infinity (TREE_TYPE (expr)))
2147 if (supports_overflow_infinity (TREE_TYPE (expr)))
2148 max = positive_overflow_infinity (TREE_TYPE (expr));
2151 set_value_range_to_varying (vr);
2156 max = TYPE_MIN_VALUE (TREE_TYPE (expr));
2158 else if (code == NEGATE_EXPR
2159 && TYPE_UNSIGNED (TREE_TYPE (expr)))
2161 if (!range_includes_zero_p (&vr0))
2163 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2164 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2168 if (range_is_null (&vr0))
2169 set_value_range_to_null (vr, TREE_TYPE (expr));
2171 set_value_range_to_varying (vr);
2175 else if (code == ABS_EXPR
2176 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
2178 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
2180 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (expr))
2181 && ((vr0.type == VR_RANGE
2182 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
2183 || (vr0.type == VR_ANTI_RANGE
2184 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
2185 && !range_includes_zero_p (&vr0))))
2187 set_value_range_to_varying (vr);
2191 /* ABS_EXPR may flip the range around, if the original range
2192 included negative values. */
2193 if (is_overflow_infinity (vr0.min))
2194 min = positive_overflow_infinity (TREE_TYPE (expr));
2195 else if (vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2196 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2197 else if (!needs_overflow_infinity (TREE_TYPE (expr)))
2198 min = TYPE_MAX_VALUE (TREE_TYPE (expr));
2199 else if (supports_overflow_infinity (TREE_TYPE (expr)))
2200 min = positive_overflow_infinity (TREE_TYPE (expr));
2203 set_value_range_to_varying (vr);
2207 if (is_overflow_infinity (vr0.max))
2208 max = positive_overflow_infinity (TREE_TYPE (expr));
2209 else if (vr0.max != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2210 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2211 else if (!needs_overflow_infinity (TREE_TYPE (expr)))
2212 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
2213 else if (supports_overflow_infinity (TREE_TYPE (expr)))
2214 max = positive_overflow_infinity (TREE_TYPE (expr));
2217 set_value_range_to_varying (vr);
2221 cmp = compare_values (min, max);
2223 /* If a VR_ANTI_RANGEs contains zero, then we have
2224 ~[-INF, min(MIN, MAX)]. */
2225 if (vr0.type == VR_ANTI_RANGE)
2227 if (range_includes_zero_p (&vr0))
2229 /* Take the lower of the two values. */
2233 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
2234 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
2235 flag_wrapv is set and the original anti-range doesn't include
2236 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
2237 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr)))
2239 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
2241 min = (vr0.min != type_min_value
2242 ? int_const_binop (PLUS_EXPR, type_min_value,
2243 integer_one_node, 0)
2248 if (overflow_infinity_range_p (&vr0))
2249 min = negative_overflow_infinity (TREE_TYPE (expr));
2251 min = TYPE_MIN_VALUE (TREE_TYPE (expr));
2256 /* All else has failed, so create the range [0, INF], even for
2257 flag_wrapv since TYPE_MIN_VALUE is in the original
2259 vr0.type = VR_RANGE;
2260 min = build_int_cst (TREE_TYPE (expr), 0);
2261 if (needs_overflow_infinity (TREE_TYPE (expr)))
2263 if (supports_overflow_infinity (TREE_TYPE (expr)))
2264 max = positive_overflow_infinity (TREE_TYPE (expr));
2267 set_value_range_to_varying (vr);
2272 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
2276 /* If the range contains zero then we know that the minimum value in the
2277 range will be zero. */
2278 else if (range_includes_zero_p (&vr0))
2282 min = build_int_cst (TREE_TYPE (expr), 0);
2286 /* If the range was reversed, swap MIN and MAX. */
2297 /* Otherwise, operate on each end of the range. */
2298 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2299 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2301 if (needs_overflow_infinity (TREE_TYPE (expr)))
2303 gcc_assert (code != NEGATE_EXPR && code != ABS_EXPR);
2304 if (is_overflow_infinity (vr0.min))
2306 else if (TREE_OVERFLOW (min))
2308 if (supports_overflow_infinity (TREE_TYPE (expr)))
2309 min = (tree_int_cst_sgn (min) >= 0
2310 ? positive_overflow_infinity (TREE_TYPE (min))
2311 : negative_overflow_infinity (TREE_TYPE (min)));
2314 set_value_range_to_varying (vr);
2319 if (is_overflow_infinity (vr0.max))
2321 else if (TREE_OVERFLOW (max))
2323 if (supports_overflow_infinity (TREE_TYPE (expr)))
2324 max = (tree_int_cst_sgn (max) >= 0
2325 ? positive_overflow_infinity (TREE_TYPE (max))
2326 : negative_overflow_infinity (TREE_TYPE (max)));
2329 set_value_range_to_varying (vr);
2336 cmp = compare_values (min, max);
2337 if (cmp == -2 || cmp == 1)
2339 /* If the new range has its limits swapped around (MIN > MAX),
2340 then the operation caused one of them to wrap around, mark
2341 the new range VARYING. */
2342 set_value_range_to_varying (vr);
2345 set_value_range (vr, vr0.type, min, max, NULL);
2349 /* Extract range information from a conditional expression EXPR based on
2350 the ranges of each of its operands and the expression code. */
2353 extract_range_from_cond_expr (value_range_t *vr, tree expr)
2356 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2357 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2359 /* Get value ranges for each operand. For constant operands, create
2360 a new value range with the operand to simplify processing. */
2361 op0 = COND_EXPR_THEN (expr);
2362 if (TREE_CODE (op0) == SSA_NAME)
2363 vr0 = *(get_value_range (op0));
2364 else if (is_gimple_min_invariant (op0))
2365 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
2367 set_value_range_to_varying (&vr0);
2369 op1 = COND_EXPR_ELSE (expr);
2370 if (TREE_CODE (op1) == SSA_NAME)
2371 vr1 = *(get_value_range (op1));
2372 else if (is_gimple_min_invariant (op1))
2373 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
2375 set_value_range_to_varying (&vr1);
2377 /* The resulting value range is the union of the operand ranges */
2378 vrp_meet (&vr0, &vr1);
2379 copy_value_range (vr, &vr0);
2383 /* Extract range information from a comparison expression EXPR based
2384 on the range of its operand and the expression code. */
2387 extract_range_from_comparison (value_range_t *vr, tree expr)
2390 tree val = vrp_evaluate_conditional_warnv (expr, false, &sop);
2392 /* A disadvantage of using a special infinity as an overflow
2393 representation is that we lose the ability to record overflow
2394 when we don't have an infinity. So we have to ignore a result
2395 which relies on overflow. */
2397 if (val && !is_overflow_infinity (val) && !sop)
2399 /* Since this expression was found on the RHS of an assignment,
2400 its type may be different from _Bool. Convert VAL to EXPR's
2402 val = fold_convert (TREE_TYPE (expr), val);
2403 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
2406 /* The result of a comparison is always true or false. */
2407 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
2411 /* Try to compute a useful range out of expression EXPR and store it
2415 extract_range_from_expr (value_range_t *vr, tree expr)
2417 enum tree_code code = TREE_CODE (expr);
2419 if (code == ASSERT_EXPR)
2420 extract_range_from_assert (vr, expr);
2421 else if (code == SSA_NAME)
2422 extract_range_from_ssa_name (vr, expr);
2423 else if (TREE_CODE_CLASS (code) == tcc_binary
2424 || code == TRUTH_ANDIF_EXPR
2425 || code == TRUTH_ORIF_EXPR
2426 || code == TRUTH_AND_EXPR
2427 || code == TRUTH_OR_EXPR
2428 || code == TRUTH_XOR_EXPR)
2429 extract_range_from_binary_expr (vr, expr);
2430 else if (TREE_CODE_CLASS (code) == tcc_unary)
2431 extract_range_from_unary_expr (vr, expr);
2432 else if (code == COND_EXPR)
2433 extract_range_from_cond_expr (vr, expr);
2434 else if (TREE_CODE_CLASS (code) == tcc_comparison)
2435 extract_range_from_comparison (vr, expr);
2436 else if (is_gimple_min_invariant (expr))
2437 set_value_range (vr, VR_RANGE, expr, expr, NULL);
2439 set_value_range_to_varying (vr);
2441 /* If we got a varying range from the tests above, try a final
2442 time to derive a nonnegative or nonzero range. This time
2443 relying primarily on generic routines in fold in conjunction
2445 if (vr->type == VR_VARYING)
2449 if (INTEGRAL_TYPE_P (TREE_TYPE (expr))
2450 && vrp_expr_computes_nonnegative (expr, &sop))
2451 set_value_range_to_nonnegative (vr, TREE_TYPE (expr),
2452 sop || is_overflow_infinity (expr));
2453 else if (vrp_expr_computes_nonzero (expr, &sop)
2455 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
2459 /* Given a range VR, a LOOP and a variable VAR, determine whether it
2460 would be profitable to adjust VR using scalar evolution information
2461 for VAR. If so, update VR with the new limits. */
2464 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
2467 tree init, step, chrec, tmin, tmax, min, max, type;
2468 enum ev_direction dir;
2470 /* TODO. Don't adjust anti-ranges. An anti-range may provide
2471 better opportunities than a regular range, but I'm not sure. */
2472 if (vr->type == VR_ANTI_RANGE)
2475 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
2476 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
2479 init = initial_condition_in_loop_num (chrec, loop->num);
2480 step = evolution_part_in_loop_num (chrec, loop->num);
2482 /* If STEP is symbolic, we can't know whether INIT will be the
2483 minimum or maximum value in the range. Also, unless INIT is
2484 a simple expression, compare_values and possibly other functions
2485 in tree-vrp won't be able to handle it. */
2486 if (step == NULL_TREE
2487 || !is_gimple_min_invariant (step)
2488 || !valid_value_p (init))
2491 dir = scev_direction (chrec);
2492 if (/* Do not adjust ranges if we do not know whether the iv increases
2493 or decreases, ... */
2494 dir == EV_DIR_UNKNOWN
2495 /* ... or if it may wrap. */
2496 || scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec),
2500 /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of
2501 negative_overflow_infinity and positive_overflow_infinity,
2502 because we have concluded that the loop probably does not
2505 type = TREE_TYPE (var);
2506 if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type))
2507 tmin = lower_bound_in_type (type, type);
2509 tmin = TYPE_MIN_VALUE (type);
2510 if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type))
2511 tmax = upper_bound_in_type (type, type);
2513 tmax = TYPE_MAX_VALUE (type);
2515 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2520 /* For VARYING or UNDEFINED ranges, just about anything we get
2521 from scalar evolutions should be better. */
2523 if (dir == EV_DIR_DECREASES)
2528 /* If we would create an invalid range, then just assume we
2529 know absolutely nothing. This may be over-conservative,
2530 but it's clearly safe, and should happen only in unreachable
2531 parts of code, or for invalid programs. */
2532 if (compare_values (min, max) == 1)
2535 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2537 else if (vr->type == VR_RANGE)
2542 if (dir == EV_DIR_DECREASES)
2544 /* INIT is the maximum value. If INIT is lower than VR->MAX
2545 but no smaller than VR->MIN, set VR->MAX to INIT. */
2546 if (compare_values (init, max) == -1)
2550 /* If we just created an invalid range with the minimum
2551 greater than the maximum, we fail conservatively.
2552 This should happen only in unreachable
2553 parts of code, or for invalid programs. */
2554 if (compare_values (min, max) == 1)
2560 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2561 if (compare_values (init, min) == 1)
2565 /* Again, avoid creating invalid range by failing. */
2566 if (compare_values (min, max) == 1)
2571 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2576 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2578 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2579 all the values in the ranges.
2581 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2583 - Return NULL_TREE if it is not always possible to determine the
2584 value of the comparison.
2586 Also set *STRICT_OVERFLOW_P to indicate whether a range with an
2587 overflow infinity was used in the test. */
2591 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1,
2592 bool *strict_overflow_p)
2594 /* VARYING or UNDEFINED ranges cannot be compared. */
2595 if (vr0->type == VR_VARYING
2596 || vr0->type == VR_UNDEFINED
2597 || vr1->type == VR_VARYING
2598 || vr1->type == VR_UNDEFINED)
2601 /* Anti-ranges need to be handled separately. */
2602 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
2604 /* If both are anti-ranges, then we cannot compute any
2606 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
2609 /* These comparisons are never statically computable. */
2616 /* Equality can be computed only between a range and an
2617 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2618 if (vr0->type == VR_RANGE)
2620 /* To simplify processing, make VR0 the anti-range. */
2621 value_range_t *tmp = vr0;
2626 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
2628 if (compare_values_warnv (vr0->min, vr1->min, strict_overflow_p) == 0
2629 && compare_values_warnv (vr0->max, vr1->max, strict_overflow_p) == 0)
2630 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2635 if (!usable_range_p (vr0, strict_overflow_p)
2636 || !usable_range_p (vr1, strict_overflow_p))
2639 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2640 operands around and change the comparison code. */
2641 if (comp == GT_EXPR || comp == GE_EXPR)
2644 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
2650 if (comp == EQ_EXPR)
2652 /* Equality may only be computed if both ranges represent
2653 exactly one value. */
2654 if (compare_values_warnv (vr0->min, vr0->max, strict_overflow_p) == 0
2655 && compare_values_warnv (vr1->min, vr1->max, strict_overflow_p) == 0)
2657 int cmp_min = compare_values_warnv (vr0->min, vr1->min,
2659 int cmp_max = compare_values_warnv (vr0->max, vr1->max,
2661 if (cmp_min == 0 && cmp_max == 0)
2662 return boolean_true_node;
2663 else if (cmp_min != -2 && cmp_max != -2)
2664 return boolean_false_node;
2666 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2667 else if (compare_values_warnv (vr0->min, vr1->max,
2668 strict_overflow_p) == 1
2669 || compare_values_warnv (vr1->min, vr0->max,
2670 strict_overflow_p) == 1)
2671 return boolean_false_node;
2675 else if (comp == NE_EXPR)
2679 /* If VR0 is completely to the left or completely to the right
2680 of VR1, they are always different. Notice that we need to
2681 make sure that both comparisons yield similar results to
2682 avoid comparing values that cannot be compared at
2684 cmp1 = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
2685 cmp2 = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
2686 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
2687 return boolean_true_node;
2689 /* If VR0 and VR1 represent a single value and are identical,
2691 else if (compare_values_warnv (vr0->min, vr0->max,
2692 strict_overflow_p) == 0
2693 && compare_values_warnv (vr1->min, vr1->max,
2694 strict_overflow_p) == 0
2695 && compare_values_warnv (vr0->min, vr1->min,
2696 strict_overflow_p) == 0
2697 && compare_values_warnv (vr0->max, vr1->max,
2698 strict_overflow_p) == 0)
2699 return boolean_false_node;
2701 /* Otherwise, they may or may not be different. */
2705 else if (comp == LT_EXPR || comp == LE_EXPR)
2709 /* If VR0 is to the left of VR1, return true. */
2710 tst = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
2711 if ((comp == LT_EXPR && tst == -1)
2712 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2714 if (overflow_infinity_range_p (vr0)
2715 || overflow_infinity_range_p (vr1))
2716 *strict_overflow_p = true;
2717 return boolean_true_node;
2720 /* If VR0 is to the right of VR1, return false. */
2721 tst = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
2722 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2723 || (comp == LE_EXPR && tst == 1))
2725 if (overflow_infinity_range_p (vr0)
2726 || overflow_infinity_range_p (vr1))
2727 *strict_overflow_p = true;
2728 return boolean_false_node;
2731 /* Otherwise, we don't know. */
2739 /* Given a value range VR, a value VAL and a comparison code COMP, return
2740 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2741 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2742 always returns false. Return NULL_TREE if it is not always
2743 possible to determine the value of the comparison. Also set
2744 *STRICT_OVERFLOW_P to indicate whether a range with an overflow
2745 infinity was used in the test. */
2748 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val,
2749 bool *strict_overflow_p)
2751 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2754 /* Anti-ranges need to be handled separately. */
2755 if (vr->type == VR_ANTI_RANGE)
2757 /* For anti-ranges, the only predicates that we can compute at
2758 compile time are equality and inequality. */
2765 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2766 if (value_inside_range (val, vr) == 1)
2767 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2772 if (!usable_range_p (vr, strict_overflow_p))
2775 if (comp == EQ_EXPR)
2777 /* EQ_EXPR may only be computed if VR represents exactly
2779 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0)
2781 int cmp = compare_values_warnv (vr->min, val, strict_overflow_p);
2783 return boolean_true_node;
2784 else if (cmp == -1 || cmp == 1 || cmp == 2)
2785 return boolean_false_node;
2787 else if (compare_values_warnv (val, vr->min, strict_overflow_p) == -1
2788 || compare_values_warnv (vr->max, val, strict_overflow_p) == -1)
2789 return boolean_false_node;
2793 else if (comp == NE_EXPR)
2795 /* If VAL is not inside VR, then they are always different. */
2796 if (compare_values_warnv (vr->max, val, strict_overflow_p) == -1
2797 || compare_values_warnv (vr->min, val, strict_overflow_p) == 1)
2798 return boolean_true_node;
2800 /* If VR represents exactly one value equal to VAL, then return
2802 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0
2803 && compare_values_warnv (vr->min, val, strict_overflow_p) == 0)
2804 return boolean_false_node;
2806 /* Otherwise, they may or may not be different. */
2809 else if (comp == LT_EXPR || comp == LE_EXPR)
2813 /* If VR is to the left of VAL, return true. */
2814 tst = compare_values_warnv (vr->max, val, strict_overflow_p);
2815 if ((comp == LT_EXPR && tst == -1)
2816 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2818 if (overflow_infinity_range_p (vr))
2819 *strict_overflow_p = true;
2820 return boolean_true_node;
2823 /* If VR is to the right of VAL, return false. */
2824 tst = compare_values_warnv (vr->min, val, strict_overflow_p);
2825 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2826 || (comp == LE_EXPR && tst == 1))
2828 if (overflow_infinity_range_p (vr))
2829 *strict_overflow_p = true;
2830 return boolean_false_node;
2833 /* Otherwise, we don't know. */
2836 else if (comp == GT_EXPR || comp == GE_EXPR)
2840 /* If VR is to the right of VAL, return true. */
2841 tst = compare_values_warnv (vr->min, val, strict_overflow_p);
2842 if ((comp == GT_EXPR && tst == 1)
2843 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
2845 if (overflow_infinity_range_p (vr))
2846 *strict_overflow_p = true;
2847 return boolean_true_node;
2850 /* If VR is to the left of VAL, return false. */
2851 tst = compare_values_warnv (vr->max, val, strict_overflow_p);
2852 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
2853 || (comp == GE_EXPR && tst == -1))
2855 if (overflow_infinity_range_p (vr))
2856 *strict_overflow_p = true;
2857 return boolean_false_node;
2860 /* Otherwise, we don't know. */
2868 /* Debugging dumps. */
2870 void dump_value_range (FILE *, value_range_t *);
2871 void debug_value_range (value_range_t *);
2872 void dump_all_value_ranges (FILE *);
2873 void debug_all_value_ranges (void);
2874 void dump_vr_equiv (FILE *, bitmap);
2875 void debug_vr_equiv (bitmap);
2878 /* Dump value range VR to FILE. */
2881 dump_value_range (FILE *file, value_range_t *vr)
2884 fprintf (file, "[]");
2885 else if (vr->type == VR_UNDEFINED)
2886 fprintf (file, "UNDEFINED");
2887 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
2889 tree type = TREE_TYPE (vr->min);
2891 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
2893 if (INTEGRAL_TYPE_P (type)
2894 && !TYPE_UNSIGNED (type)
2895 && vr->min == TYPE_MIN_VALUE (type))
2896 fprintf (file, "-INF");
2897 else if (needs_overflow_infinity (type)
2898 && is_negative_overflow_infinity (vr->min))
2899 fprintf (file, "-INF(OVF)");
2901 print_generic_expr (file, vr->min, 0);
2903 fprintf (file, ", ");
2905 if (INTEGRAL_TYPE_P (type)
2906 && vr->max == TYPE_MAX_VALUE (type))
2907 fprintf (file, "+INF");
2908 else if (needs_overflow_infinity (type)
2909 && is_positive_overflow_infinity (vr->max))
2910 fprintf (file, "+INF(OVF)");
2912 print_generic_expr (file, vr->max, 0);
2914 fprintf (file, "]");
2921 fprintf (file, " EQUIVALENCES: { ");
2923 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
2925 print_generic_expr (file, ssa_name (i), 0);
2926 fprintf (file, " ");
2930 fprintf (file, "} (%u elements)", c);
2933 else if (vr->type == VR_VARYING)
2934 fprintf (file, "VARYING");
2936 fprintf (file, "INVALID RANGE");
2940 /* Dump value range VR to stderr. */
2943 debug_value_range (value_range_t *vr)
2945 dump_value_range (stderr, vr);
2946 fprintf (stderr, "\n");
2950 /* Dump value ranges of all SSA_NAMEs to FILE. */
2953 dump_all_value_ranges (FILE *file)
2957 for (i = 0; i < num_ssa_names; i++)
2961 print_generic_expr (file, ssa_name (i), 0);
2962 fprintf (file, ": ");
2963 dump_value_range (file, vr_value[i]);
2964 fprintf (file, "\n");
2968 fprintf (file, "\n");
2972 /* Dump all value ranges to stderr. */
2975 debug_all_value_ranges (void)
2977 dump_all_value_ranges (stderr);
2981 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
2982 create a new SSA name N and return the assertion assignment
2983 'V = ASSERT_EXPR <V, V OP W>'. */
2986 build_assert_expr_for (tree cond, tree v)
2990 gcc_assert (TREE_CODE (v) == SSA_NAME);
2991 n = duplicate_ssa_name (v, NULL_TREE);
2993 if (COMPARISON_CLASS_P (cond))
2995 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
2996 assertion = build2 (GIMPLE_MODIFY_STMT, TREE_TYPE (v), n, a);
2998 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
3000 /* Given !V, build the assignment N = false. */
3001 tree op0 = TREE_OPERAND (cond, 0);
3002 gcc_assert (op0 == v);
3003 assertion = build2 (GIMPLE_MODIFY_STMT, TREE_TYPE (v), n,
3004 boolean_false_node);
3006 else if (TREE_CODE (cond) == SSA_NAME)
3008 /* Given V, build the assignment N = true. */
3009 gcc_assert (v == cond);
3010 assertion = build2 (GIMPLE_MODIFY_STMT,
3011 TREE_TYPE (v), n, boolean_true_node);
3016 SSA_NAME_DEF_STMT (n) = assertion;
3018 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
3019 operand of the ASSERT_EXPR. Register the new name and the old one
3020 in the replacement table so that we can fix the SSA web after
3021 adding all the ASSERT_EXPRs. */
3022 register_new_name_mapping (n, v);
3028 /* Return false if EXPR is a predicate expression involving floating
3032 fp_predicate (tree expr)
3034 return (COMPARISON_CLASS_P (expr)
3035 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
3039 /* If the range of values taken by OP can be inferred after STMT executes,
3040 return the comparison code (COMP_CODE_P) and value (VAL_P) that
3041 describes the inferred range. Return true if a range could be
3045 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
3048 *comp_code_p = ERROR_MARK;
3050 /* Do not attempt to infer anything in names that flow through
3052 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
3055 /* Similarly, don't infer anything from statements that may throw
3057 if (tree_could_throw_p (stmt))
3060 /* If STMT is the last statement of a basic block with no
3061 successors, there is no point inferring anything about any of its
3062 operands. We would not be able to find a proper insertion point
3063 for the assertion, anyway. */
3064 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
3067 /* We can only assume that a pointer dereference will yield
3068 non-NULL if -fdelete-null-pointer-checks is enabled. */
3069 if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op)))
3072 unsigned num_uses, num_derefs;
3074 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
3077 *val_p = build_int_cst (TREE_TYPE (op), 0);
3078 *comp_code_p = NE_EXPR;
3087 void dump_asserts_for (FILE *, tree);
3088 void debug_asserts_for (tree);
3089 void dump_all_asserts (FILE *);
3090 void debug_all_asserts (void);
3092 /* Dump all the registered assertions for NAME to FILE. */
3095 dump_asserts_for (FILE *file, tree name)
3099 fprintf (file, "Assertions to be inserted for ");
3100 print_generic_expr (file, name, 0);
3101 fprintf (file, "\n");
3103 loc = asserts_for[SSA_NAME_VERSION (name)];
3106 fprintf (file, "\t");
3107 print_generic_expr (file, bsi_stmt (loc->si), 0);
3108 fprintf (file, "\n\tBB #%d", loc->bb->index);
3111 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
3112 loc->e->dest->index);
3113 dump_edge_info (file, loc->e, 0);
3115 fprintf (file, "\n\tPREDICATE: ");
3116 print_generic_expr (file, name, 0);
3117 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
3118 print_generic_expr (file, loc->val, 0);
3119 fprintf (file, "\n\n");
3123 fprintf (file, "\n");
3127 /* Dump all the registered assertions for NAME to stderr. */
3130 debug_asserts_for (tree name)
3132 dump_asserts_for (stderr, name);
3136 /* Dump all the registered assertions for all the names to FILE. */
3139 dump_all_asserts (FILE *file)
3144 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
3145 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3146 dump_asserts_for (file, ssa_name (i));
3147 fprintf (file, "\n");
3151 /* Dump all the registered assertions for all the names to stderr. */
3154 debug_all_asserts (void)
3156 dump_all_asserts (stderr);
3160 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
3161 'NAME COMP_CODE VAL' at a location that dominates block BB or
3162 E->DEST, then register this location as a possible insertion point
3163 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
3165 BB, E and SI provide the exact insertion point for the new
3166 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
3167 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
3168 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
3169 must not be NULL. */
3172 register_new_assert_for (tree name,
3173 enum tree_code comp_code,
3177 block_stmt_iterator si)
3179 assert_locus_t n, loc, last_loc;
3181 basic_block dest_bb;
3183 #if defined ENABLE_CHECKING
3184 gcc_assert (bb == NULL || e == NULL);
3187 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
3188 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
3191 /* The new assertion A will be inserted at BB or E. We need to
3192 determine if the new location is dominated by a previously
3193 registered location for A. If we are doing an edge insertion,
3194 assume that A will be inserted at E->DEST. Note that this is not
3197 If E is a critical edge, it will be split. But even if E is
3198 split, the new block will dominate the same set of blocks that
3201 The reverse, however, is not true, blocks dominated by E->DEST
3202 will not be dominated by the new block created to split E. So,
3203 if the insertion location is on a critical edge, we will not use
3204 the new location to move another assertion previously registered
3205 at a block dominated by E->DEST. */
3206 dest_bb = (bb) ? bb : e->dest;
3208 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
3209 VAL at a block dominating DEST_BB, then we don't need to insert a new
3210 one. Similarly, if the same assertion already exists at a block
3211 dominated by DEST_BB and the new location is not on a critical
3212 edge, then update the existing location for the assertion (i.e.,
3213 move the assertion up in the dominance tree).
3215 Note, this is implemented as a simple linked list because there
3216 should not be more than a handful of assertions registered per
3217 name. If this becomes a performance problem, a table hashed by
3218 COMP_CODE and VAL could be implemented. */
3219 loc = asserts_for[SSA_NAME_VERSION (name)];
3224 if (loc->comp_code == comp_code
3226 || operand_equal_p (loc->val, val, 0)))
3228 /* If the assertion NAME COMP_CODE VAL has already been
3229 registered at a basic block that dominates DEST_BB, then
3230 we don't need to insert the same assertion again. Note
3231 that we don't check strict dominance here to avoid
3232 replicating the same assertion inside the same basic
3233 block more than once (e.g., when a pointer is
3234 dereferenced several times inside a block).
3236 An exception to this rule are edge insertions. If the
3237 new assertion is to be inserted on edge E, then it will
3238 dominate all the other insertions that we may want to
3239 insert in DEST_BB. So, if we are doing an edge
3240 insertion, don't do this dominance check. */
3242 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
3245 /* Otherwise, if E is not a critical edge and DEST_BB
3246 dominates the existing location for the assertion, move
3247 the assertion up in the dominance tree by updating its
3248 location information. */
3249 if ((e == NULL || !EDGE_CRITICAL_P (e))
3250 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
3259 /* Update the last node of the list and move to the next one. */
3264 /* If we didn't find an assertion already registered for
3265 NAME COMP_CODE VAL, add a new one at the end of the list of
3266 assertions associated with NAME. */
3267 n = XNEW (struct assert_locus_d);
3271 n->comp_code = comp_code;
3278 asserts_for[SSA_NAME_VERSION (name)] = n;
3280 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
3283 /* COND is a predicate which uses NAME. Extract a suitable test code
3284 and value and store them into *CODE_P and *VAL_P so the predicate
3285 is normalized to NAME *CODE_P *VAL_P.
3287 If no extraction was possible, return FALSE, otherwise return TRUE.
3289 If INVERT is true, then we invert the result stored into *CODE_P. */
3292 extract_code_and_val_from_cond (tree name, tree cond, bool invert,
3293 enum tree_code *code_p, tree *val_p)
3295 enum tree_code comp_code;
3298 /* Predicates may be a single SSA name or NAME OP VAL. */
3301 /* If the predicate is a name, it must be NAME, in which
3302 case we create the predicate NAME == true or
3303 NAME == false accordingly. */
3304 comp_code = EQ_EXPR;
3305 val = invert ? boolean_false_node : boolean_true_node;
3309 /* Otherwise, we have a comparison of the form NAME COMP VAL
3310 or VAL COMP NAME. */
3311 if (name == TREE_OPERAND (cond, 1))
3313 /* If the predicate is of the form VAL COMP NAME, flip
3314 COMP around because we need to register NAME as the
3315 first operand in the predicate. */
3316 comp_code = swap_tree_comparison (TREE_CODE (cond));
3317 val = TREE_OPERAND (cond, 0);
3321 /* The comparison is of the form NAME COMP VAL, so the
3322 comparison code remains unchanged. */
3323 comp_code = TREE_CODE (cond);
3324 val = TREE_OPERAND (cond, 1);
3327 /* Invert the comparison code as necessary. */
3329 comp_code = invert_tree_comparison (comp_code, 0);
3331 /* VRP does not handle float types. */
3332 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)))
3335 /* Do not register always-false predicates.
3336 FIXME: this works around a limitation in fold() when dealing with
3337 enumerations. Given 'enum { N1, N2 } x;', fold will not
3338 fold 'if (x > N2)' to 'if (0)'. */
3339 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
3340 && INTEGRAL_TYPE_P (TREE_TYPE (val)))
3342 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
3343 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
3345 if (comp_code == GT_EXPR
3347 || compare_values (val, max) == 0))
3350 if (comp_code == LT_EXPR
3352 || compare_values (val, min) == 0))
3356 *code_p = comp_code;
3361 /* OP is an operand of a truth value expression which is known to have
3362 a particular value. Register any asserts for OP and for any
3363 operands in OP's defining statement.
3365 If CODE is EQ_EXPR, then we want to register OP is zero (false),
3366 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
3369 register_edge_assert_for_1 (tree op, enum tree_code code,
3370 edge e, block_stmt_iterator bsi)
3372 bool retval = false;
3373 tree op_def, rhs, val;
3375 /* We only care about SSA_NAMEs. */
3376 if (TREE_CODE (op) != SSA_NAME)
3379 /* We know that OP will have a zero or nonzero value. If OP is used
3380 more than once go ahead and register an assert for OP.
3382 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
3383 it will always be set for OP (because OP is used in a COND_EXPR in
3385 if (!has_single_use (op))
3387 val = build_int_cst (TREE_TYPE (op), 0);
3388 register_new_assert_for (op, code, val, NULL, e, bsi);
3392 /* Now look at how OP is set. If it's set from a comparison,
3393 a truth operation or some bit operations, then we may be able
3394 to register information about the operands of that assignment. */
3395 op_def = SSA_NAME_DEF_STMT (op);
3396 if (TREE_CODE (op_def) != GIMPLE_MODIFY_STMT)
3399 rhs = GIMPLE_STMT_OPERAND (op_def, 1);
3401 if (COMPARISON_CLASS_P (rhs))
3403 bool invert = (code == EQ_EXPR ? true : false);
3404 tree op0 = TREE_OPERAND (rhs, 0);
3405 tree op1 = TREE_OPERAND (rhs, 1);
3407 /* Conditionally register an assert for each SSA_NAME in the
3409 if (TREE_CODE (op0) == SSA_NAME
3410 && !has_single_use (op0)
3411 && extract_code_and_val_from_cond (op0, rhs,
3412 invert, &code, &val))
3414 register_new_assert_for (op0, code, val, NULL, e, bsi);
3418 /* Similarly for the second operand of the comparison. */
3419 if (TREE_CODE (op1) == SSA_NAME
3420 && !has_single_use (op1)
3421 && extract_code_and_val_from_cond (op1, rhs,
3422 invert, &code, &val))
3424 register_new_assert_for (op1, code, val, NULL, e, bsi);
3428 else if ((code == NE_EXPR
3429 && (TREE_CODE (rhs) == TRUTH_AND_EXPR
3430 || TREE_CODE (rhs) == BIT_AND_EXPR))
3432 && (TREE_CODE (rhs) == TRUTH_OR_EXPR
3433 || TREE_CODE (rhs) == BIT_IOR_EXPR)))
3435 /* Recurse on each operand. */
3436 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3438 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 1),
3441 else if (TREE_CODE (rhs) == TRUTH_NOT_EXPR)
3443 /* Recurse, flipping CODE. */
3444 code = invert_tree_comparison (code, false);
3445 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3448 else if (TREE_CODE (rhs) == SSA_NAME)
3450 /* Recurse through the copy. */
3451 retval |= register_edge_assert_for_1 (rhs, code, e, bsi);
3453 else if (TREE_CODE (rhs) == NOP_EXPR
3454 || TREE_CODE (rhs) == CONVERT_EXPR
3455 || TREE_CODE (rhs) == VIEW_CONVERT_EXPR
3456 || TREE_CODE (rhs) == NON_LVALUE_EXPR)
3458 /* Recurse through the type conversion. */
3459 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3466 /* Try to register an edge assertion for SSA name NAME on edge E for
3467 the condition COND contributing to the conditional jump pointed to by SI.
3468 Return true if an assertion for NAME could be registered. */
3471 register_edge_assert_for (tree name, edge e, block_stmt_iterator si, tree cond)
3474 enum tree_code comp_code;
3475 bool retval = false;
3476 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
3478 /* Do not attempt to infer anything in names that flow through
3480 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
3483 if (!extract_code_and_val_from_cond (name, cond, is_else_edge,
3487 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
3488 reachable from E. */
3489 if (TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
3491 register_new_assert_for (name, comp_code, val, NULL, e, si);
3495 /* If COND is effectively an equality test of an SSA_NAME against
3496 the value zero or one, then we may be able to assert values
3497 for SSA_NAMEs which flow into COND. */
3499 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
3500 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
3501 have nonzero value. */
3502 if (((comp_code == EQ_EXPR && integer_onep (val))
3503 || (comp_code == NE_EXPR && integer_zerop (val))))
3505 tree def_stmt = SSA_NAME_DEF_STMT (name);
3507 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3508 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_AND_EXPR
3509 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_AND_EXPR))
3511 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3512 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3513 retval |= register_edge_assert_for_1 (op0, NE_EXPR, e, si);
3514 retval |= register_edge_assert_for_1 (op1, NE_EXPR, e, si);
3518 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
3519 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
3521 if (((comp_code == EQ_EXPR && integer_zerop (val))
3522 || (comp_code == NE_EXPR && integer_onep (val))))
3524 tree def_stmt = SSA_NAME_DEF_STMT (name);
3526 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3527 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_OR_EXPR
3528 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_IOR_EXPR))
3530 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3531 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3532 retval |= register_edge_assert_for_1 (op0, EQ_EXPR, e, si);
3533 retval |= register_edge_assert_for_1 (op1, EQ_EXPR, e, si);
3541 static bool find_assert_locations (basic_block bb);
3543 /* Determine whether the outgoing edges of BB should receive an
3544 ASSERT_EXPR for each of the operands of BB's LAST statement.
3545 The last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
3547 If any of the sub-graphs rooted at BB have an interesting use of
3548 the predicate operands, an assert location node is added to the
3549 list of assertions for the corresponding operands. */
3552 find_conditional_asserts (basic_block bb, tree last)
3555 block_stmt_iterator bsi;
3561 need_assert = false;
3562 bsi = bsi_for_stmt (last);
3564 /* Look for uses of the operands in each of the sub-graphs
3565 rooted at BB. We need to check each of the outgoing edges
3566 separately, so that we know what kind of ASSERT_EXPR to
3568 FOR_EACH_EDGE (e, ei, bb->succs)
3573 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
3574 Otherwise, when we finish traversing each of the sub-graphs, we
3575 won't know whether the variables were found in the sub-graphs or
3576 if they had been found in a block upstream from BB.
3578 This is actually a bad idea is some cases, particularly jump
3579 threading. Consider a CFG like the following:
3589 Assume that one or more operands in the conditional at the
3590 end of block 0 are used in a conditional in block 2, but not
3591 anywhere in block 1. In this case we will not insert any
3592 assert statements in block 1, which may cause us to miss
3593 opportunities to optimize, particularly for jump threading. */
3594 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3595 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3597 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3598 to determine if any of the operands in the conditional
3599 predicate are used. */
3601 need_assert |= find_assert_locations (e->dest);
3603 /* Register the necessary assertions for each operand in the
3604 conditional predicate. */
3605 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3606 need_assert |= register_edge_assert_for (op, e, bsi,
3607 COND_EXPR_COND (last));
3610 /* Finally, indicate that we have found the operands in the
3612 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3613 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3619 /* Traverse all the statements in block BB looking for statements that
3620 may generate useful assertions for the SSA names in their operand.
3621 If a statement produces a useful assertion A for name N_i, then the
3622 list of assertions already generated for N_i is scanned to
3623 determine if A is actually needed.
3625 If N_i already had the assertion A at a location dominating the
3626 current location, then nothing needs to be done. Otherwise, the
3627 new location for A is recorded instead.
3629 1- For every statement S in BB, all the variables used by S are
3630 added to bitmap FOUND_IN_SUBGRAPH.
3632 2- If statement S uses an operand N in a way that exposes a known
3633 value range for N, then if N was not already generated by an
3634 ASSERT_EXPR, create a new assert location for N. For instance,
3635 if N is a pointer and the statement dereferences it, we can
3636 assume that N is not NULL.
3638 3- COND_EXPRs are a special case of #2. We can derive range
3639 information from the predicate but need to insert different
3640 ASSERT_EXPRs for each of the sub-graphs rooted at the
3641 conditional block. If the last statement of BB is a conditional
3642 expression of the form 'X op Y', then
3644 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
3646 b) If the conditional is the only entry point to the sub-graph
3647 corresponding to the THEN_CLAUSE, recurse into it. On
3648 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
3649 an ASSERT_EXPR is added for the corresponding variable.
3651 c) Repeat step (b) on the ELSE_CLAUSE.
3653 d) Mark X and Y in FOUND_IN_SUBGRAPH.
3662 In this case, an assertion on the THEN clause is useful to
3663 determine that 'a' is always 9 on that edge. However, an assertion
3664 on the ELSE clause would be unnecessary.
3666 4- If BB does not end in a conditional expression, then we recurse
3667 into BB's dominator children.
3669 At the end of the recursive traversal, every SSA name will have a
3670 list of locations where ASSERT_EXPRs should be added. When a new
3671 location for name N is found, it is registered by calling
3672 register_new_assert_for. That function keeps track of all the
3673 registered assertions to prevent adding unnecessary assertions.
3674 For instance, if a pointer P_4 is dereferenced more than once in a
3675 dominator tree, only the location dominating all the dereference of
3676 P_4 will receive an ASSERT_EXPR.
3678 If this function returns true, then it means that there are names
3679 for which we need to generate ASSERT_EXPRs. Those assertions are
3680 inserted by process_assert_insertions.
3682 TODO. Handle SWITCH_EXPR. */
3685 find_assert_locations (basic_block bb)
3687 block_stmt_iterator si;
3692 if (TEST_BIT (blocks_visited, bb->index))
3695 SET_BIT (blocks_visited, bb->index);
3697 need_assert = false;
3699 /* Traverse all PHI nodes in BB marking used operands. */
3700 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3702 use_operand_p arg_p;
3705 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
3707 tree arg = USE_FROM_PTR (arg_p);
3708 if (TREE_CODE (arg) == SSA_NAME)
3710 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
3711 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
3716 /* Traverse all the statements in BB marking used names and looking
3717 for statements that may infer assertions for their used operands. */
3719 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3724 stmt = bsi_stmt (si);
3726 /* See if we can derive an assertion for any of STMT's operands. */
3727 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
3730 enum tree_code comp_code;
3732 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
3733 the sub-graph of a conditional block, when we return from
3734 this recursive walk, our parent will use the
3735 FOUND_IN_SUBGRAPH bitset to determine if one of the
3736 operands it was looking for was present in the sub-graph. */
3737 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3739 /* If OP is used in such a way that we can infer a value
3740 range for it, and we don't find a previous assertion for
3741 it, create a new assertion location node for OP. */
3742 if (infer_value_range (stmt, op, &comp_code, &value))
3744 /* If we are able to infer a nonzero value range for OP,
3745 then walk backwards through the use-def chain to see if OP
3746 was set via a typecast.
3748 If so, then we can also infer a nonzero value range
3749 for the operand of the NOP_EXPR. */
3750 if (comp_code == NE_EXPR && integer_zerop (value))
3753 tree def_stmt = SSA_NAME_DEF_STMT (t);
3755 while (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3757 (GIMPLE_STMT_OPERAND (def_stmt, 1)) == NOP_EXPR
3759 (TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1),
3762 (TREE_TYPE (TREE_OPERAND
3763 (GIMPLE_STMT_OPERAND (def_stmt,
3766 t = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3767 def_stmt = SSA_NAME_DEF_STMT (t);
3769 /* Note we want to register the assert for the
3770 operand of the NOP_EXPR after SI, not after the
3772 if (! has_single_use (t))
3774 register_new_assert_for (t, comp_code, value,
3781 /* If OP is used only once, namely in this STMT, don't
3782 bother creating an ASSERT_EXPR for it. Such an
3783 ASSERT_EXPR would do nothing but increase compile time. */
3784 if (!has_single_use (op))
3786 register_new_assert_for (op, comp_code, value, bb, NULL, si);
3792 /* Remember the last statement of the block. */
3796 /* If BB's last statement is a conditional expression
3797 involving integer operands, recurse into each of the sub-graphs
3798 rooted at BB to determine if we need to add ASSERT_EXPRs. */
3800 && TREE_CODE (last) == COND_EXPR
3801 && !fp_predicate (COND_EXPR_COND (last))
3802 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
3803 need_assert |= find_conditional_asserts (bb, last);
3805 /* Recurse into the dominator children of BB. */
3806 for (son = first_dom_son (CDI_DOMINATORS, bb);
3808 son = next_dom_son (CDI_DOMINATORS, son))
3809 need_assert |= find_assert_locations (son);
3815 /* Create an ASSERT_EXPR for NAME and insert it in the location
3816 indicated by LOC. Return true if we made any edge insertions. */
3819 process_assert_insertions_for (tree name, assert_locus_t loc)
3821 /* Build the comparison expression NAME_i COMP_CODE VAL. */
3822 tree stmt, cond, assert_expr;
3826 cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
3827 assert_expr = build_assert_expr_for (cond, name);
3831 /* We have been asked to insert the assertion on an edge. This
3832 is used only by COND_EXPR and SWITCH_EXPR assertions. */
3833 #if defined ENABLE_CHECKING
3834 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
3835 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
3838 bsi_insert_on_edge (loc->e, assert_expr);
3842 /* Otherwise, we can insert right after LOC->SI iff the
3843 statement must not be the last statement in the block. */
3844 stmt = bsi_stmt (loc->si);
3845 if (!stmt_ends_bb_p (stmt))
3847 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
3851 /* If STMT must be the last statement in BB, we can only insert new
3852 assertions on the non-abnormal edge out of BB. Note that since
3853 STMT is not control flow, there may only be one non-abnormal edge
3855 FOR_EACH_EDGE (e, ei, loc->bb->succs)
3856 if (!(e->flags & EDGE_ABNORMAL))
3858 bsi_insert_on_edge (e, assert_expr);
3866 /* Process all the insertions registered for every name N_i registered
3867 in NEED_ASSERT_FOR. The list of assertions to be inserted are
3868 found in ASSERTS_FOR[i]. */
3871 process_assert_insertions (void)
3875 bool update_edges_p = false;
3876 int num_asserts = 0;
3878 if (dump_file && (dump_flags & TDF_DETAILS))
3879 dump_all_asserts (dump_file);
3881 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3883 assert_locus_t loc = asserts_for[i];
3888 assert_locus_t next = loc->next;
3889 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
3897 bsi_commit_edge_inserts ();
3899 if (dump_file && (dump_flags & TDF_STATS))
3900 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
3905 /* Traverse the flowgraph looking for conditional jumps to insert range
3906 expressions. These range expressions are meant to provide information
3907 to optimizations that need to reason in terms of value ranges. They
3908 will not be expanded into RTL. For instance, given:
3917 this pass will transform the code into:
3923 x = ASSERT_EXPR <x, x < y>
3928 y = ASSERT_EXPR <y, x <= y>
3932 The idea is that once copy and constant propagation have run, other
3933 optimizations will be able to determine what ranges of values can 'x'
3934 take in different paths of the code, simply by checking the reaching
3935 definition of 'x'. */
3938 insert_range_assertions (void)
3944 found_in_subgraph = sbitmap_alloc (num_ssa_names);
3945 sbitmap_zero (found_in_subgraph);
3947 blocks_visited = sbitmap_alloc (last_basic_block);
3948 sbitmap_zero (blocks_visited);
3950 need_assert_for = BITMAP_ALLOC (NULL);
3951 asserts_for = XCNEWVEC (assert_locus_t, num_ssa_names);
3953 calculate_dominance_info (CDI_DOMINATORS);
3955 update_ssa_p = false;
3956 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3957 if (find_assert_locations (e->dest))
3958 update_ssa_p = true;
3962 process_assert_insertions ();
3963 update_ssa (TODO_update_ssa_no_phi);
3966 if (dump_file && (dump_flags & TDF_DETAILS))
3968 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
3969 dump_function_to_file (current_function_decl, dump_file, dump_flags);
3972 sbitmap_free (found_in_subgraph);
3974 BITMAP_FREE (need_assert_for);
3977 /* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays
3978 and "struct" hacks. If VRP can determine that the
3979 array subscript is a constant, check if it is outside valid
3980 range. If the array subscript is a RANGE, warn if it is
3981 non-overlapping with valid range.
3982 IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */
3985 check_array_ref (tree ref, location_t* locus, bool ignore_off_by_one)
3987 value_range_t* vr = NULL;
3988 tree low_sub, up_sub;
3989 tree low_bound, up_bound = array_ref_up_bound (ref);
3991 low_sub = up_sub = TREE_OPERAND (ref, 1);
3993 if (!up_bound || !locus || TREE_NO_WARNING (ref)
3994 || TREE_CODE (up_bound) != INTEGER_CST
3995 /* Can not check flexible arrays. */
3996 || (TYPE_SIZE (TREE_TYPE (ref)) == NULL_TREE
3997 && TYPE_DOMAIN (TREE_TYPE (ref)) != NULL_TREE
3998 && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (ref))) == NULL_TREE)
3999 /* Accesses after the end of arrays of size 0 (gcc
4000 extension) and 1 are likely intentional ("struct
4002 || compare_tree_int (up_bound, 1) <= 0)
4005 low_bound = array_ref_low_bound (ref);
4007 if (TREE_CODE (low_sub) == SSA_NAME)
4009 vr = get_value_range (low_sub);
4010 if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
4012 low_sub = vr->type == VR_RANGE ? vr->max : vr->min;
4013 up_sub = vr->type == VR_RANGE ? vr->min : vr->max;
4017 if (vr && vr->type == VR_ANTI_RANGE)
4019 if (TREE_CODE (up_sub) == INTEGER_CST
4020 && tree_int_cst_lt (up_bound, up_sub)
4021 && TREE_CODE (low_sub) == INTEGER_CST
4022 && tree_int_cst_lt (low_sub, low_bound))
4024 warning (OPT_Warray_bounds,
4025 "%Harray subscript is outside array bounds", locus);
4026 TREE_NO_WARNING (ref) = 1;
4029 else if (TREE_CODE (up_sub) == INTEGER_CST
4030 && tree_int_cst_lt (up_bound, up_sub)
4031 && !tree_int_cst_equal (up_bound, up_sub)
4032 && (!ignore_off_by_one
4033 || !tree_int_cst_equal (int_const_binop (PLUS_EXPR,
4039 warning (OPT_Warray_bounds, "%Harray subscript is above array bounds",
4041 TREE_NO_WARNING (ref) = 1;
4043 else if (TREE_CODE (low_sub) == INTEGER_CST
4044 && tree_int_cst_lt (low_sub, low_bound))
4046 warning (OPT_Warray_bounds, "%Harray subscript is below array bounds",
4048 TREE_NO_WARNING (ref) = 1;
4052 /* walk_tree() callback that checks if *TP is
4053 an ARRAY_REF inside an ADDR_EXPR (in which an array
4054 subscript one outside the valid range is allowed). Call
4055 check_array_ref for each ARRAY_REF found. The location is
4059 check_array_bounds (tree *tp, int *walk_subtree, void *data)
4062 tree stmt = (tree)data;
4063 location_t *location = EXPR_LOCUS (stmt);
4065 *walk_subtree = TRUE;
4067 if (TREE_CODE (t) == ARRAY_REF)
4068 check_array_ref (t, location, false /*ignore_off_by_one*/);
4069 else if (TREE_CODE (t) == ADDR_EXPR)
4073 t = TREE_OPERAND (t, 0);
4075 /* Don't warn on statements like
4077 ssa_name = 500 + &array[-200]
4081 ssa_name = &array[-200]
4082 other_name = ssa_name + 300;
4085 produced by other optimizing passes. */
4087 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
4088 && BINARY_CLASS_P (GIMPLE_STMT_OPERAND (stmt, 1)))
4089 *walk_subtree = FALSE;
4091 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
4092 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 0)) == SSA_NAME
4093 && single_imm_use (GIMPLE_STMT_OPERAND (stmt, 0), &op, &use_stmt)
4094 && TREE_CODE (use_stmt) == GIMPLE_MODIFY_STMT
4095 && BINARY_CLASS_P (GIMPLE_STMT_OPERAND (use_stmt, 1)))
4096 *walk_subtree = FALSE;
4098 while (*walk_subtree && handled_component_p (t))
4100 if (TREE_CODE (t) == ARRAY_REF)
4101 check_array_ref (t, location, true /*ignore_off_by_one*/);
4102 t = TREE_OPERAND (t, 0);
4104 *walk_subtree = FALSE;
4110 /* Walk over all statements of all reachable BBs and call check_array_bounds
4114 check_all_array_refs (void)
4117 block_stmt_iterator si;
4121 /* Skip bb's that are clearly unreachable. */
4122 if (single_pred_p (bb))
4124 basic_block pred_bb = EDGE_PRED (bb, 0)->src;
4125 tree ls = NULL_TREE;
4127 if (!bsi_end_p (bsi_last (pred_bb)))
4128 ls = bsi_stmt (bsi_last (pred_bb));
4130 if (ls && TREE_CODE (ls) == COND_EXPR
4131 && ((COND_EXPR_COND (ls) == boolean_false_node
4132 && (EDGE_PRED (bb, 0)->flags & EDGE_TRUE_VALUE))
4133 || (COND_EXPR_COND (ls) == boolean_true_node
4134 && (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE))))
4137 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
4138 walk_tree (bsi_stmt_ptr (si), check_array_bounds,
4139 bsi_stmt (si), NULL);
4143 /* Convert range assertion expressions into the implied copies and
4144 copy propagate away the copies. Doing the trivial copy propagation
4145 here avoids the need to run the full copy propagation pass after
4148 FIXME, this will eventually lead to copy propagation removing the
4149 names that had useful range information attached to them. For
4150 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
4151 then N_i will have the range [3, +INF].
4153 However, by converting the assertion into the implied copy
4154 operation N_i = N_j, we will then copy-propagate N_j into the uses
4155 of N_i and lose the range information. We may want to hold on to
4156 ASSERT_EXPRs a little while longer as the ranges could be used in
4157 things like jump threading.
4159 The problem with keeping ASSERT_EXPRs around is that passes after
4160 VRP need to handle them appropriately.
4162 Another approach would be to make the range information a first
4163 class property of the SSA_NAME so that it can be queried from
4164 any pass. This is made somewhat more complex by the need for
4165 multiple ranges to be associated with one SSA_NAME. */
4168 remove_range_assertions (void)
4171 block_stmt_iterator si;
4173 /* Note that the BSI iterator bump happens at the bottom of the
4174 loop and no bump is necessary if we're removing the statement
4175 referenced by the current BSI. */
4177 for (si = bsi_start (bb); !bsi_end_p (si);)
4179 tree stmt = bsi_stmt (si);
4182 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
4183 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ASSERT_EXPR)
4185 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1), var;
4186 tree cond = fold (ASSERT_EXPR_COND (rhs));
4187 use_operand_p use_p;
4188 imm_use_iterator iter;
4190 gcc_assert (cond != boolean_false_node);
4192 /* Propagate the RHS into every use of the LHS. */
4193 var = ASSERT_EXPR_VAR (rhs);
4194 FOR_EACH_IMM_USE_STMT (use_stmt, iter,
4195 GIMPLE_STMT_OPERAND (stmt, 0))
4196 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
4198 SET_USE (use_p, var);
4199 gcc_assert (TREE_CODE (var) == SSA_NAME);
4202 /* And finally, remove the copy, it is not needed. */
4203 bsi_remove (&si, true);
4204 release_defs (stmt);
4210 sbitmap_free (blocks_visited);
4214 /* Return true if STMT is interesting for VRP. */
4217 stmt_interesting_for_vrp (tree stmt)
4219 if (TREE_CODE (stmt) == PHI_NODE
4220 && is_gimple_reg (PHI_RESULT (stmt))
4221 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
4222 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
4224 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4226 tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
4227 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4229 /* In general, assignments with virtual operands are not useful
4230 for deriving ranges, with the obvious exception of calls to
4231 builtin functions. */
4232 if (TREE_CODE (lhs) == SSA_NAME
4233 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
4234 || POINTER_TYPE_P (TREE_TYPE (lhs)))
4235 && ((TREE_CODE (rhs) == CALL_EXPR
4236 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
4237 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs), 0))
4238 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
4239 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)))
4242 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
4249 /* Initialize local data structures for VRP. */
4252 vrp_initialize (void)
4256 vr_value = XCNEWVEC (value_range_t *, num_ssa_names);
4260 block_stmt_iterator si;
4263 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4265 if (!stmt_interesting_for_vrp (phi))
4267 tree lhs = PHI_RESULT (phi);
4268 set_value_range_to_varying (get_value_range (lhs));
4269 DONT_SIMULATE_AGAIN (phi) = true;
4272 DONT_SIMULATE_AGAIN (phi) = false;
4275 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
4277 tree stmt = bsi_stmt (si);
4279 if (!stmt_interesting_for_vrp (stmt))
4283 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
4284 set_value_range_to_varying (get_value_range (def));
4285 DONT_SIMULATE_AGAIN (stmt) = true;
4289 DONT_SIMULATE_AGAIN (stmt) = false;
4296 /* Visit assignment STMT. If it produces an interesting range, record
4297 the SSA name in *OUTPUT_P. */
4299 static enum ssa_prop_result
4300 vrp_visit_assignment (tree stmt, tree *output_p)
4305 lhs = GIMPLE_STMT_OPERAND (stmt, 0);
4306 rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4308 /* We only keep track of ranges in integral and pointer types. */
4309 if (TREE_CODE (lhs) == SSA_NAME
4310 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
4311 /* It is valid to have NULL MIN/MAX values on a type. See
4312 build_range_type. */
4313 && TYPE_MIN_VALUE (TREE_TYPE (lhs))
4314 && TYPE_MAX_VALUE (TREE_TYPE (lhs)))
4315 || POINTER_TYPE_P (TREE_TYPE (lhs))))
4318 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
4320 extract_range_from_expr (&new_vr, rhs);
4322 /* If STMT is inside a loop, we may be able to know something
4323 else about the range of LHS by examining scalar evolution
4325 if (current_loops && (l = loop_containing_stmt (stmt)))
4326 adjust_range_with_scev (&new_vr, l, stmt, lhs);
4328 if (update_value_range (lhs, &new_vr))
4332 if (dump_file && (dump_flags & TDF_DETAILS))
4334 fprintf (dump_file, "Found new range for ");
4335 print_generic_expr (dump_file, lhs, 0);
4336 fprintf (dump_file, ": ");
4337 dump_value_range (dump_file, &new_vr);
4338 fprintf (dump_file, "\n\n");
4341 if (new_vr.type == VR_VARYING)
4342 return SSA_PROP_VARYING;
4344 return SSA_PROP_INTERESTING;
4347 return SSA_PROP_NOT_INTERESTING;
4350 /* Every other statement produces no useful ranges. */
4351 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
4352 set_value_range_to_varying (get_value_range (def));
4354 return SSA_PROP_VARYING;
4358 /* Compare all the value ranges for names equivalent to VAR with VAL
4359 using comparison code COMP. Return the same value returned by
4360 compare_range_with_value, including the setting of
4361 *STRICT_OVERFLOW_P. */
4364 compare_name_with_value (enum tree_code comp, tree var, tree val,
4365 bool *strict_overflow_p)
4371 int used_strict_overflow;
4373 t = retval = NULL_TREE;
4375 /* Get the set of equivalences for VAR. */
4376 e = get_value_range (var)->equiv;
4378 /* Add VAR to its own set of equivalences so that VAR's value range
4379 is processed by this loop (otherwise, we would have to replicate
4380 the body of the loop just to check VAR's value range). */
4381 bitmap_set_bit (e, SSA_NAME_VERSION (var));
4383 /* Start at -1. Set it to 0 if we do a comparison without relying
4384 on overflow, or 1 if all comparisons rely on overflow. */
4385 used_strict_overflow = -1;
4387 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
4391 value_range_t equiv_vr = *(vr_value[i]);
4393 /* If name N_i does not have a valid range, use N_i as its own
4394 range. This allows us to compare against names that may
4395 have N_i in their ranges. */
4396 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
4398 equiv_vr.type = VR_RANGE;
4399 equiv_vr.min = ssa_name (i);
4400 equiv_vr.max = ssa_name (i);
4404 t = compare_range_with_value (comp, &equiv_vr, val, &sop);
4407 /* If we get different answers from different members
4408 of the equivalence set this check must be in a dead
4409 code region. Folding it to a trap representation
4410 would be correct here. For now just return don't-know. */
4420 used_strict_overflow = 0;
4421 else if (used_strict_overflow < 0)
4422 used_strict_overflow = 1;
4426 /* Remove VAR from its own equivalence set. */
4427 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
4431 if (used_strict_overflow > 0)
4432 *strict_overflow_p = true;
4436 /* We couldn't find a non-NULL value for the predicate. */
4441 /* Given a comparison code COMP and names N1 and N2, compare all the
4442 ranges equivalent to N1 against all the ranges equivalent to N2
4443 to determine the value of N1 COMP N2. Return the same value
4444 returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate
4445 whether we relied on an overflow infinity in the comparison. */
4449 compare_names (enum tree_code comp, tree n1, tree n2,
4450 bool *strict_overflow_p)
4454 bitmap_iterator bi1, bi2;
4456 int used_strict_overflow;
4458 /* Compare the ranges of every name equivalent to N1 against the
4459 ranges of every name equivalent to N2. */
4460 e1 = get_value_range (n1)->equiv;
4461 e2 = get_value_range (n2)->equiv;
4463 /* Add N1 and N2 to their own set of equivalences to avoid
4464 duplicating the body of the loop just to check N1 and N2
4466 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
4467 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
4469 /* If the equivalence sets have a common intersection, then the two
4470 names can be compared without checking their ranges. */
4471 if (bitmap_intersect_p (e1, e2))
4473 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4474 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4476 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
4478 : boolean_false_node;
4481 /* Start at -1. Set it to 0 if we do a comparison without relying
4482 on overflow, or 1 if all comparisons rely on overflow. */
4483 used_strict_overflow = -1;
4485 /* Otherwise, compare all the equivalent ranges. First, add N1 and
4486 N2 to their own set of equivalences to avoid duplicating the body
4487 of the loop just to check N1 and N2 ranges. */
4488 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
4490 value_range_t vr1 = *(vr_value[i1]);
4492 /* If the range is VARYING or UNDEFINED, use the name itself. */
4493 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
4495 vr1.type = VR_RANGE;
4496 vr1.min = ssa_name (i1);
4497 vr1.max = ssa_name (i1);
4500 t = retval = NULL_TREE;
4501 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
4505 value_range_t vr2 = *(vr_value[i2]);
4507 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
4509 vr2.type = VR_RANGE;
4510 vr2.min = ssa_name (i2);
4511 vr2.max = ssa_name (i2);
4514 t = compare_ranges (comp, &vr1, &vr2, &sop);
4517 /* If we get different answers from different members
4518 of the equivalence set this check must be in a dead
4519 code region. Folding it to a trap representation
4520 would be correct here. For now just return don't-know. */
4524 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4525 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4531 used_strict_overflow = 0;
4532 else if (used_strict_overflow < 0)
4533 used_strict_overflow = 1;
4539 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4540 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4541 if (used_strict_overflow > 0)
4542 *strict_overflow_p = true;
4547 /* None of the equivalent ranges are useful in computing this
4549 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4550 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4555 /* Given a conditional predicate COND, try to determine if COND yields
4556 true or false based on the value ranges of its operands. Return
4557 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
4558 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
4559 NULL if the conditional cannot be evaluated at compile time.
4561 If USE_EQUIV_P is true, the ranges of all the names equivalent with
4562 the operands in COND are used when trying to compute its value.
4563 This is only used during final substitution. During propagation,
4564 we only check the range of each variable and not its equivalents.
4566 Set *STRICT_OVERFLOW_P to indicate whether we relied on an overflow
4567 infinity to produce the result. */
4570 vrp_evaluate_conditional_warnv (tree cond, bool use_equiv_p,
4571 bool *strict_overflow_p)
4573 gcc_assert (TREE_CODE (cond) == SSA_NAME
4574 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
4576 if (TREE_CODE (cond) == SSA_NAME)
4582 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node,
4586 value_range_t *vr = get_value_range (cond);
4587 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node,
4591 /* If COND has a known boolean range, return it. */
4595 /* Otherwise, if COND has a symbolic range of exactly one value,
4597 vr = get_value_range (cond);
4598 if (vr->type == VR_RANGE && vr->min == vr->max)
4603 tree op0 = TREE_OPERAND (cond, 0);
4604 tree op1 = TREE_OPERAND (cond, 1);
4606 /* We only deal with integral and pointer types. */
4607 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
4608 && !POINTER_TYPE_P (TREE_TYPE (op0)))
4613 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
4614 return compare_names (TREE_CODE (cond), op0, op1,
4616 else if (TREE_CODE (op0) == SSA_NAME)
4617 return compare_name_with_value (TREE_CODE (cond), op0, op1,
4619 else if (TREE_CODE (op1) == SSA_NAME)
4620 return (compare_name_with_value
4621 (swap_tree_comparison (TREE_CODE (cond)), op1, op0,
4622 strict_overflow_p));
4626 value_range_t *vr0, *vr1;
4628 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
4629 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
4632 return compare_ranges (TREE_CODE (cond), vr0, vr1,
4634 else if (vr0 && vr1 == NULL)
4635 return compare_range_with_value (TREE_CODE (cond), vr0, op1,
4637 else if (vr0 == NULL && vr1)
4638 return (compare_range_with_value
4639 (swap_tree_comparison (TREE_CODE (cond)), vr1, op0,
4640 strict_overflow_p));
4644 /* Anything else cannot be computed statically. */
4648 /* Given COND within STMT, try to simplify it based on value range
4649 information. Return NULL if the conditional can not be evaluated.
4650 The ranges of all the names equivalent with the operands in COND
4651 will be used when trying to compute the value. If the result is
4652 based on undefined signed overflow, issue a warning if
4656 vrp_evaluate_conditional (tree cond, tree stmt)
4662 ret = vrp_evaluate_conditional_warnv (cond, true, &sop);
4666 enum warn_strict_overflow_code wc;
4667 const char* warnmsg;
4669 if (is_gimple_min_invariant (ret))
4671 wc = WARN_STRICT_OVERFLOW_CONDITIONAL;
4672 warnmsg = G_("assuming signed overflow does not occur when "
4673 "simplifying conditional to constant");
4677 wc = WARN_STRICT_OVERFLOW_COMPARISON;
4678 warnmsg = G_("assuming signed overflow does not occur when "
4679 "simplifying conditional");
4682 if (issue_strict_overflow_warning (wc))
4686 if (!EXPR_HAS_LOCATION (stmt))
4687 locus = input_location;
4689 locus = EXPR_LOCATION (stmt);
4690 warning (OPT_Wstrict_overflow, "%H%s", &locus, warnmsg);
4698 /* Visit conditional statement STMT. If we can determine which edge
4699 will be taken out of STMT's basic block, record it in
4700 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
4701 SSA_PROP_VARYING. */
4703 static enum ssa_prop_result
4704 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
4709 *taken_edge_p = NULL;
4711 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
4712 add ASSERT_EXPRs for them. */
4713 if (TREE_CODE (stmt) == SWITCH_EXPR)
4714 return SSA_PROP_VARYING;
4716 cond = COND_EXPR_COND (stmt);
4718 if (dump_file && (dump_flags & TDF_DETAILS))
4723 fprintf (dump_file, "\nVisiting conditional with predicate: ");
4724 print_generic_expr (dump_file, cond, 0);
4725 fprintf (dump_file, "\nWith known ranges\n");
4727 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
4729 fprintf (dump_file, "\t");
4730 print_generic_expr (dump_file, use, 0);
4731 fprintf (dump_file, ": ");
4732 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
4735 fprintf (dump_file, "\n");
4738 /* Compute the value of the predicate COND by checking the known
4739 ranges of each of its operands.
4741 Note that we cannot evaluate all the equivalent ranges here
4742 because those ranges may not yet be final and with the current
4743 propagation strategy, we cannot determine when the value ranges
4744 of the names in the equivalence set have changed.
4746 For instance, given the following code fragment
4750 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
4754 Assume that on the first visit to i_14, i_5 has the temporary
4755 range [8, 8] because the second argument to the PHI function is
4756 not yet executable. We derive the range ~[0, 0] for i_14 and the
4757 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
4758 the first time, since i_14 is equivalent to the range [8, 8], we
4759 determine that the predicate is always false.
4761 On the next round of propagation, i_13 is determined to be
4762 VARYING, which causes i_5 to drop down to VARYING. So, another
4763 visit to i_14 is scheduled. In this second visit, we compute the
4764 exact same range and equivalence set for i_14, namely ~[0, 0] and
4765 { i_5 }. But we did not have the previous range for i_5
4766 registered, so vrp_visit_assignment thinks that the range for
4767 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
4768 is not visited again, which stops propagation from visiting
4769 statements in the THEN clause of that if().
4771 To properly fix this we would need to keep the previous range
4772 value for the names in the equivalence set. This way we would've
4773 discovered that from one visit to the other i_5 changed from
4774 range [8, 8] to VR_VARYING.
4776 However, fixing this apparent limitation may not be worth the
4777 additional checking. Testing on several code bases (GCC, DLV,
4778 MICO, TRAMP3D and SPEC2000) showed that doing this results in
4779 4 more predicates folded in SPEC. */
4781 val = vrp_evaluate_conditional_warnv (cond, false, &sop);
4785 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
4788 if (dump_file && (dump_flags & TDF_DETAILS))
4790 "\nIgnoring predicate evaluation because "
4791 "it assumes that signed overflow is undefined");
4796 if (dump_file && (dump_flags & TDF_DETAILS))
4798 fprintf (dump_file, "\nPredicate evaluates to: ");
4799 if (val == NULL_TREE)
4800 fprintf (dump_file, "DON'T KNOW\n");
4802 print_generic_stmt (dump_file, val, 0);
4805 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
4809 /* Evaluate statement STMT. If the statement produces a useful range,
4810 return SSA_PROP_INTERESTING and record the SSA name with the
4811 interesting range into *OUTPUT_P.
4813 If STMT is a conditional branch and we can determine its truth
4814 value, the taken edge is recorded in *TAKEN_EDGE_P.
4816 If STMT produces a varying value, return SSA_PROP_VARYING. */
4818 static enum ssa_prop_result
4819 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
4825 if (dump_file && (dump_flags & TDF_DETAILS))
4827 fprintf (dump_file, "\nVisiting statement:\n");
4828 print_generic_stmt (dump_file, stmt, dump_flags);
4829 fprintf (dump_file, "\n");
4832 ann = stmt_ann (stmt);
4833 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4835 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4837 /* In general, assignments with virtual operands are not useful
4838 for deriving ranges, with the obvious exception of calls to
4839 builtin functions. */
4840 if ((TREE_CODE (rhs) == CALL_EXPR
4841 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
4842 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs), 0))
4843 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
4844 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
4845 return vrp_visit_assignment (stmt, output_p);
4847 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
4848 return vrp_visit_cond_stmt (stmt, taken_edge_p);
4850 /* All other statements produce nothing of interest for VRP, so mark
4851 their outputs varying and prevent further simulation. */
4852 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
4853 set_value_range_to_varying (get_value_range (def));
4855 return SSA_PROP_VARYING;
4859 /* Meet operation for value ranges. Given two value ranges VR0 and
4860 VR1, store in VR0 a range that contains both VR0 and VR1. This
4861 may not be the smallest possible such range. */
4864 vrp_meet (value_range_t *vr0, value_range_t *vr1)
4866 if (vr0->type == VR_UNDEFINED)
4868 copy_value_range (vr0, vr1);
4872 if (vr1->type == VR_UNDEFINED)
4874 /* Nothing to do. VR0 already has the resulting range. */
4878 if (vr0->type == VR_VARYING)
4880 /* Nothing to do. VR0 already has the resulting range. */
4884 if (vr1->type == VR_VARYING)
4886 set_value_range_to_varying (vr0);
4890 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
4895 /* Compute the convex hull of the ranges. The lower limit of
4896 the new range is the minimum of the two ranges. If they
4897 cannot be compared, then give up. */
4898 cmp = compare_values (vr0->min, vr1->min);
4899 if (cmp == 0 || cmp == 1)
4906 /* Similarly, the upper limit of the new range is the maximum
4907 of the two ranges. If they cannot be compared, then
4909 cmp = compare_values (vr0->max, vr1->max);
4910 if (cmp == 0 || cmp == -1)
4917 /* The resulting set of equivalences is the intersection of
4919 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4920 bitmap_and_into (vr0->equiv, vr1->equiv);
4921 else if (vr0->equiv && !vr1->equiv)
4922 bitmap_clear (vr0->equiv);
4924 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
4926 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
4928 /* Two anti-ranges meet only if their complements intersect.
4929 Only handle the case of identical ranges. */
4930 if (compare_values (vr0->min, vr1->min) == 0
4931 && compare_values (vr0->max, vr1->max) == 0
4932 && compare_values (vr0->min, vr0->max) == 0)
4934 /* The resulting set of equivalences is the intersection of
4936 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4937 bitmap_and_into (vr0->equiv, vr1->equiv);
4938 else if (vr0->equiv && !vr1->equiv)
4939 bitmap_clear (vr0->equiv);
4944 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
4946 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
4947 only handle the case where the ranges have an empty intersection.
4948 The result of the meet operation is the anti-range. */
4949 if (!symbolic_range_p (vr0)
4950 && !symbolic_range_p (vr1)
4951 && !value_ranges_intersect_p (vr0, vr1))
4953 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
4954 set. We need to compute the intersection of the two
4955 equivalence sets. */
4956 if (vr1->type == VR_ANTI_RANGE)
4957 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
4959 /* The resulting set of equivalences is the intersection of
4961 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4962 bitmap_and_into (vr0->equiv, vr1->equiv);
4963 else if (vr0->equiv && !vr1->equiv)
4964 bitmap_clear (vr0->equiv);
4975 /* Failed to find an efficient meet. Before giving up and setting
4976 the result to VARYING, see if we can at least derive a useful
4977 anti-range. FIXME, all this nonsense about distinguishing
4978 anti-ranges from ranges is necessary because of the odd
4979 semantics of range_includes_zero_p and friends. */
4980 if (!symbolic_range_p (vr0)
4981 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
4982 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
4983 && !symbolic_range_p (vr1)
4984 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
4985 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
4987 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
4989 /* Since this meet operation did not result from the meeting of
4990 two equivalent names, VR0 cannot have any equivalences. */
4992 bitmap_clear (vr0->equiv);
4995 set_value_range_to_varying (vr0);
4999 /* Visit all arguments for PHI node PHI that flow through executable
5000 edges. If a valid value range can be derived from all the incoming
5001 value ranges, set a new range for the LHS of PHI. */
5003 static enum ssa_prop_result
5004 vrp_visit_phi_node (tree phi)
5007 tree lhs = PHI_RESULT (phi);
5008 value_range_t *lhs_vr = get_value_range (lhs);
5009 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
5010 bool all_const = true;
5012 copy_value_range (&vr_result, lhs_vr);
5014 if (dump_file && (dump_flags & TDF_DETAILS))
5016 fprintf (dump_file, "\nVisiting PHI node: ");
5017 print_generic_expr (dump_file, phi, dump_flags);
5020 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
5022 edge e = PHI_ARG_EDGE (phi, i);
5024 if (dump_file && (dump_flags & TDF_DETAILS))
5027 "\n Argument #%d (%d -> %d %sexecutable)\n",
5028 i, e->src->index, e->dest->index,
5029 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
5032 if (e->flags & EDGE_EXECUTABLE)
5034 tree arg = PHI_ARG_DEF (phi, i);
5035 value_range_t vr_arg;
5037 if (TREE_CODE (arg) == SSA_NAME)
5039 vr_arg = *(get_value_range (arg));
5044 vr_arg.type = VR_RANGE;
5047 vr_arg.equiv = NULL;
5050 if (dump_file && (dump_flags & TDF_DETAILS))
5052 fprintf (dump_file, "\t");
5053 print_generic_expr (dump_file, arg, dump_flags);
5054 fprintf (dump_file, "\n\tValue: ");
5055 dump_value_range (dump_file, &vr_arg);
5056 fprintf (dump_file, "\n");
5059 vrp_meet (&vr_result, &vr_arg);
5061 if (vr_result.type == VR_VARYING)
5066 if (vr_result.type == VR_VARYING)
5069 /* To prevent infinite iterations in the algorithm, derive ranges
5070 when the new value is slightly bigger or smaller than the
5072 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE
5075 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
5077 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
5078 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
5080 /* If the new minimum is smaller or larger than the previous
5081 one, go all the way to -INF. In the first case, to avoid
5082 iterating millions of times to reach -INF, and in the
5083 other case to avoid infinite bouncing between different
5085 if (cmp_min > 0 || cmp_min < 0)
5087 /* If we will end up with a (-INF, +INF) range, set it
5089 if (is_positive_overflow_infinity (vr_result.max)
5091 == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max))))
5094 if (!needs_overflow_infinity (TREE_TYPE (vr_result.min)))
5095 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
5096 else if (supports_overflow_infinity (TREE_TYPE (vr_result.min)))
5098 negative_overflow_infinity (TREE_TYPE (vr_result.min));
5103 /* Similarly, if the new maximum is smaller or larger than
5104 the previous one, go all the way to +INF. */
5105 if (cmp_max < 0 || cmp_max > 0)
5107 /* If we will end up with a (-INF, +INF) range, set it
5109 if (is_negative_overflow_infinity (vr_result.min)
5111 == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))))
5114 if (!needs_overflow_infinity (TREE_TYPE (vr_result.max)))
5115 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
5116 else if (supports_overflow_infinity (TREE_TYPE (vr_result.max)))
5118 positive_overflow_infinity (TREE_TYPE (vr_result.max));
5125 /* If the new range is different than the previous value, keep
5127 if (update_value_range (lhs, &vr_result))
5128 return SSA_PROP_INTERESTING;
5130 /* Nothing changed, don't add outgoing edges. */
5131 return SSA_PROP_NOT_INTERESTING;
5133 /* No match found. Set the LHS to VARYING. */
5135 set_value_range_to_varying (lhs_vr);
5136 return SSA_PROP_VARYING;
5139 /* Simplify a division or modulo operator to a right shift or
5140 bitwise and if the first operand is unsigned or is greater
5141 than zero and the second operand is an exact power of two. */
5144 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
5147 tree op = TREE_OPERAND (rhs, 0);
5148 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
5150 if (TYPE_UNSIGNED (TREE_TYPE (op)))
5152 val = integer_one_node;
5158 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node, &sop);
5162 && integer_onep (val)
5163 && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
5167 if (!EXPR_HAS_LOCATION (stmt))
5168 locus = input_location;
5170 locus = EXPR_LOCATION (stmt);
5171 warning (OPT_Wstrict_overflow,
5172 ("%Hassuming signed overflow does not occur when "
5173 "simplifying / or %% to >> or &"),
5178 if (val && integer_onep (val))
5181 tree op0 = TREE_OPERAND (rhs, 0);
5182 tree op1 = TREE_OPERAND (rhs, 1);
5184 if (rhs_code == TRUNC_DIV_EXPR)
5186 t = build_int_cst (NULL_TREE, tree_log2 (op1));
5187 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
5191 t = build_int_cst (TREE_TYPE (op1), 1);
5192 t = int_const_binop (MINUS_EXPR, op1, t, 0);
5193 t = fold_convert (TREE_TYPE (op0), t);
5194 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
5197 GIMPLE_STMT_OPERAND (stmt, 1) = t;
5202 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
5203 ABS_EXPR. If the operand is <= 0, then simplify the
5204 ABS_EXPR into a NEGATE_EXPR. */
5207 simplify_abs_using_ranges (tree stmt, tree rhs)
5210 tree op = TREE_OPERAND (rhs, 0);
5211 tree type = TREE_TYPE (op);
5212 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
5214 if (TYPE_UNSIGNED (type))
5216 val = integer_zero_node;
5222 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node, &sop);
5226 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node,
5231 if (integer_zerop (val))
5232 val = integer_one_node;
5233 else if (integer_onep (val))
5234 val = integer_zero_node;
5239 && (integer_onep (val) || integer_zerop (val)))
5243 if (sop && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
5247 if (!EXPR_HAS_LOCATION (stmt))
5248 locus = input_location;
5250 locus = EXPR_LOCATION (stmt);
5251 warning (OPT_Wstrict_overflow,
5252 ("%Hassuming signed overflow does not occur when "
5253 "simplifying abs (X) to X or -X"),
5257 if (integer_onep (val))
5258 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
5262 GIMPLE_STMT_OPERAND (stmt, 1) = t;
5268 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
5269 a known value range VR.
5271 If there is one and only one value which will satisfy the
5272 conditional, then return that value. Else return NULL. */
5275 test_for_singularity (enum tree_code cond_code, tree op0,
5276 tree op1, value_range_t *vr)
5281 /* Extract minimum/maximum values which satisfy the
5282 the conditional as it was written. */
5283 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
5285 /* This should not be negative infinity; there is no overflow
5287 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
5290 if (cond_code == LT_EXPR && !is_overflow_infinity (max))
5292 tree one = build_int_cst (TREE_TYPE (op0), 1);
5293 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
5296 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
5298 /* This should not be positive infinity; there is no overflow
5300 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
5303 if (cond_code == GT_EXPR && !is_overflow_infinity (min))
5305 tree one = build_int_cst (TREE_TYPE (op0), 1);
5306 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
5310 /* Now refine the minimum and maximum values using any
5311 value range information we have for op0. */
5314 if (compare_values (vr->min, min) == -1)
5318 if (compare_values (vr->max, max) == 1)
5323 /* If the new min/max values have converged to a single value,
5324 then there is only one value which can satisfy the condition,
5325 return that value. */
5326 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
5332 /* Simplify a conditional using a relational operator to an equality
5333 test if the range information indicates only one value can satisfy
5334 the original conditional. */
5337 simplify_cond_using_ranges (tree stmt)
5339 tree cond = COND_EXPR_COND (stmt);
5340 tree op0 = TREE_OPERAND (cond, 0);
5341 tree op1 = TREE_OPERAND (cond, 1);
5342 enum tree_code cond_code = TREE_CODE (cond);
5344 if (cond_code != NE_EXPR
5345 && cond_code != EQ_EXPR
5346 && TREE_CODE (op0) == SSA_NAME
5347 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
5348 && is_gimple_min_invariant (op1))
5350 value_range_t *vr = get_value_range (op0);
5352 /* If we have range information for OP0, then we might be
5353 able to simplify this conditional. */
5354 if (vr->type == VR_RANGE)
5356 tree new = test_for_singularity (cond_code, op0, op1, vr);
5362 fprintf (dump_file, "Simplified relational ");
5363 print_generic_expr (dump_file, cond, 0);
5364 fprintf (dump_file, " into ");
5367 COND_EXPR_COND (stmt)
5368 = build2 (EQ_EXPR, boolean_type_node, op0, new);
5373 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
5374 fprintf (dump_file, "\n");
5380 /* Try again after inverting the condition. We only deal
5381 with integral types here, so no need to worry about
5382 issues with inverting FP comparisons. */
5383 cond_code = invert_tree_comparison (cond_code, false);
5384 new = test_for_singularity (cond_code, op0, op1, vr);
5390 fprintf (dump_file, "Simplified relational ");
5391 print_generic_expr (dump_file, cond, 0);
5392 fprintf (dump_file, " into ");
5395 COND_EXPR_COND (stmt)
5396 = build2 (NE_EXPR, boolean_type_node, op0, new);
5401 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
5402 fprintf (dump_file, "\n");
5411 /* Simplify STMT using ranges if possible. */
5414 simplify_stmt_using_ranges (tree stmt)
5416 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
5418 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
5419 enum tree_code rhs_code = TREE_CODE (rhs);
5421 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
5422 and BIT_AND_EXPR respectively if the first operand is greater
5423 than zero and the second operand is an exact power of two. */
5424 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
5425 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
5426 && integer_pow2p (TREE_OPERAND (rhs, 1)))
5427 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
5429 /* Transform ABS (X) into X or -X as appropriate. */
5430 if (rhs_code == ABS_EXPR
5431 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
5432 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
5433 simplify_abs_using_ranges (stmt, rhs);
5435 else if (TREE_CODE (stmt) == COND_EXPR
5436 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
5438 simplify_cond_using_ranges (stmt);
5442 /* Stack of dest,src equivalency pairs that need to be restored after
5443 each attempt to thread a block's incoming edge to an outgoing edge.
5445 A NULL entry is used to mark the end of pairs which need to be
5447 static VEC(tree,heap) *stack;
5449 /* A trivial wrapper so that we can present the generic jump threading
5450 code with a simple API for simplifying statements. STMT is the
5451 statement we want to simplify, WITHIN_STMT provides the location
5452 for any overflow warnings. */
5455 simplify_stmt_for_jump_threading (tree stmt, tree within_stmt)
5457 /* We only use VRP information to simplify conditionals. This is
5458 overly conservative, but it's unclear if doing more would be
5459 worth the compile time cost. */
5460 if (TREE_CODE (stmt) != COND_EXPR)
5463 return vrp_evaluate_conditional (COND_EXPR_COND (stmt), within_stmt);
5466 /* Blocks which have more than one predecessor and more than
5467 one successor present jump threading opportunities. ie,
5468 when the block is reached from a specific predecessor, we
5469 may be able to determine which of the outgoing edges will
5470 be traversed. When this optimization applies, we are able
5471 to avoid conditionals at runtime and we may expose secondary
5472 optimization opportunities.
5474 This routine is effectively a driver for the generic jump
5475 threading code. It basically just presents the generic code
5476 with edges that may be suitable for jump threading.
5478 Unlike DOM, we do not iterate VRP if jump threading was successful.
5479 While iterating may expose new opportunities for VRP, it is expected
5480 those opportunities would be very limited and the compile time cost
5481 to expose those opportunities would be significant.
5483 As jump threading opportunities are discovered, they are registered
5484 for later realization. */
5487 identify_jump_threads (void)
5492 /* Ugh. When substituting values earlier in this pass we can
5493 wipe the dominance information. So rebuild the dominator
5494 information as we need it within the jump threading code. */
5495 calculate_dominance_info (CDI_DOMINATORS);
5497 /* We do not allow VRP information to be used for jump threading
5498 across a back edge in the CFG. Otherwise it becomes too
5499 difficult to avoid eliminating loop exit tests. Of course
5500 EDGE_DFS_BACK is not accurate at this time so we have to
5502 mark_dfs_back_edges ();
5504 /* Allocate our unwinder stack to unwind any temporary equivalences
5505 that might be recorded. */
5506 stack = VEC_alloc (tree, heap, 20);
5508 /* To avoid lots of silly node creation, we create a single
5509 conditional and just modify it in-place when attempting to
5511 dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL);
5512 dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL);
5514 /* Walk through all the blocks finding those which present a
5515 potential jump threading opportunity. We could set this up
5516 as a dominator walker and record data during the walk, but
5517 I doubt it's worth the effort for the classes of jump
5518 threading opportunities we are trying to identify at this
5519 point in compilation. */
5524 /* If the generic jump threading code does not find this block
5525 interesting, then there is nothing to do. */
5526 if (! potentially_threadable_block (bb))
5529 /* We only care about blocks ending in a COND_EXPR. While there
5530 may be some value in handling SWITCH_EXPR here, I doubt it's
5531 terribly important. */
5532 last = bsi_stmt (bsi_last (bb));
5533 if (TREE_CODE (last) != COND_EXPR)
5536 /* We're basically looking for any kind of conditional with
5537 integral type arguments. */
5538 cond = COND_EXPR_COND (last);
5539 if ((TREE_CODE (cond) == SSA_NAME
5540 && INTEGRAL_TYPE_P (TREE_TYPE (cond)))
5541 || (COMPARISON_CLASS_P (cond)
5542 && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
5543 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0)))
5544 && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME
5545 || is_gimple_min_invariant (TREE_OPERAND (cond, 1)))
5546 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
5551 /* We've got a block with multiple predecessors and multiple
5552 successors which also ends in a suitable conditional. For
5553 each predecessor, see if we can thread it to a specific
5555 FOR_EACH_EDGE (e, ei, bb->preds)
5557 /* Do not thread across back edges or abnormal edges
5559 if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
5562 thread_across_edge (dummy, e, true,
5564 simplify_stmt_for_jump_threading);
5569 /* We do not actually update the CFG or SSA graphs at this point as
5570 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
5571 handle ASSERT_EXPRs gracefully. */
5574 /* We identified all the jump threading opportunities earlier, but could
5575 not transform the CFG at that time. This routine transforms the
5576 CFG and arranges for the dominator tree to be rebuilt if necessary.
5578 Note the SSA graph update will occur during the normal TODO
5579 processing by the pass manager. */
5581 finalize_jump_threads (void)
5583 bool cfg_altered = false;
5584 cfg_altered = thread_through_all_blocks ();
5586 /* If we threaded jumps, then we need to recompute the dominance
5589 free_dominance_info (CDI_DOMINATORS);
5590 VEC_free (tree, heap, stack);
5594 /* Traverse all the blocks folding conditionals with known ranges. */
5600 prop_value_t *single_val_range;
5601 bool do_value_subst_p;
5605 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
5606 dump_all_value_ranges (dump_file);
5607 fprintf (dump_file, "\n");
5610 /* We may have ended with ranges that have exactly one value. Those
5611 values can be substituted as any other copy/const propagated
5612 value using substitute_and_fold. */
5613 single_val_range = XCNEWVEC (prop_value_t, num_ssa_names);
5615 do_value_subst_p = false;
5616 for (i = 0; i < num_ssa_names; i++)
5618 && vr_value[i]->type == VR_RANGE
5619 && vr_value[i]->min == vr_value[i]->max)
5621 single_val_range[i].value = vr_value[i]->min;
5622 do_value_subst_p = true;
5625 if (!do_value_subst_p)
5627 /* We found no single-valued ranges, don't waste time trying to
5628 do single value substitution in substitute_and_fold. */
5629 free (single_val_range);
5630 single_val_range = NULL;
5633 substitute_and_fold (single_val_range, true);
5635 if (warn_array_bounds)
5636 check_all_array_refs ();
5638 /* We must identify jump threading opportunities before we release
5639 the datastructures built by VRP. */
5640 identify_jump_threads ();
5642 /* Free allocated memory. */
5643 for (i = 0; i < num_ssa_names; i++)
5646 BITMAP_FREE (vr_value[i]->equiv);
5650 free (single_val_range);
5653 /* So that we can distinguish between VRP data being available
5654 and not available. */
5659 /* Main entry point to VRP (Value Range Propagation). This pass is
5660 loosely based on J. R. C. Patterson, ``Accurate Static Branch
5661 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
5662 Programming Language Design and Implementation, pp. 67-78, 1995.
5663 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
5665 This is essentially an SSA-CCP pass modified to deal with ranges
5666 instead of constants.
5668 While propagating ranges, we may find that two or more SSA name
5669 have equivalent, though distinct ranges. For instance,
5672 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
5674 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
5678 In the code above, pointer p_5 has range [q_2, q_2], but from the
5679 code we can also determine that p_5 cannot be NULL and, if q_2 had
5680 a non-varying range, p_5's range should also be compatible with it.
5682 These equivalences are created by two expressions: ASSERT_EXPR and
5683 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
5684 result of another assertion, then we can use the fact that p_5 and
5685 p_4 are equivalent when evaluating p_5's range.
5687 Together with value ranges, we also propagate these equivalences
5688 between names so that we can take advantage of information from
5689 multiple ranges when doing final replacement. Note that this
5690 equivalency relation is transitive but not symmetric.
5692 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
5693 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
5694 in contexts where that assertion does not hold (e.g., in line 6).
5696 TODO, the main difference between this pass and Patterson's is that
5697 we do not propagate edge probabilities. We only compute whether
5698 edges can be taken or not. That is, instead of having a spectrum
5699 of jump probabilities between 0 and 1, we only deal with 0, 1 and
5700 DON'T KNOW. In the future, it may be worthwhile to propagate
5701 probabilities to aid branch prediction. */
5706 insert_range_assertions ();
5708 loop_optimizer_init (LOOPS_NORMAL);
5713 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
5719 loop_optimizer_finalize ();
5722 /* ASSERT_EXPRs must be removed before finalizing jump threads
5723 as finalizing jump threads calls the CFG cleanup code which
5724 does not properly handle ASSERT_EXPRs. */
5725 remove_range_assertions ();
5727 /* If we exposed any new variables, go ahead and put them into
5728 SSA form now, before we handle jump threading. This simplifies
5729 interactions between rewriting of _DECL nodes into SSA form
5730 and rewriting SSA_NAME nodes into SSA form after block
5731 duplication and CFG manipulation. */
5732 update_ssa (TODO_update_ssa);
5734 finalize_jump_threads ();
5741 return flag_tree_vrp != 0;
5744 struct tree_opt_pass pass_vrp =
5747 gate_vrp, /* gate */
5748 execute_vrp, /* execute */
5751 0, /* static_pass_number */
5752 TV_TREE_VRP, /* tv_id */
5753 PROP_ssa | PROP_alias, /* properties_required */
5754 0, /* properties_provided */
5755 0, /* properties_destroyed */
5756 0, /* todo_flags_start */
5762 | TODO_update_smt_usage, /* todo_flags_finish */