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 adding infinities of different signs,
1523 since we can't tell what the sign of the result should be.
1524 Likewise for subtracting infinities of the same sign. */
1525 if (((code == PLUS_EXPR && sgn1 != sgn2)
1526 || (code == MINUS_EXPR && sgn1 == sgn2))
1527 && is_overflow_infinity (val1)
1528 && is_overflow_infinity (val2))
1531 /* Don't try to handle division or shifting of infinities. */
1532 if ((code == TRUNC_DIV_EXPR
1533 || code == FLOOR_DIV_EXPR
1534 || code == CEIL_DIV_EXPR
1535 || code == EXACT_DIV_EXPR
1536 || code == ROUND_DIV_EXPR
1537 || code == RSHIFT_EXPR)
1538 && (is_overflow_infinity (val1)
1539 || is_overflow_infinity (val2)))
1542 /* Notice that we only need to handle the restricted set of
1543 operations handled by extract_range_from_binary_expr.
1544 Among them, only multiplication, addition and subtraction
1545 can yield overflow without overflown operands because we
1546 are working with integral types only... except in the
1547 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1548 for division too. */
1550 /* For multiplication, the sign of the overflow is given
1551 by the comparison of the signs of the operands. */
1552 if ((code == MULT_EXPR && sgn1 == sgn2)
1553 /* For addition, the operands must be of the same sign
1554 to yield an overflow. Its sign is therefore that
1555 of one of the operands, for example the first. For
1556 infinite operands X + -INF is negative, not positive. */
1557 || (code == PLUS_EXPR
1559 ? !is_negative_overflow_infinity (val2)
1560 : is_positive_overflow_infinity (val2)))
1561 /* For subtraction, non-infinite operands must be of
1562 different signs to yield an overflow. Its sign is
1563 therefore that of the first operand or the opposite of
1564 that of the second operand. A first operand of 0 counts
1565 as positive here, for the corner case 0 - (-INF), which
1566 overflows, but must yield +INF. For infinite operands 0
1567 - INF is negative, not positive. */
1568 || (code == MINUS_EXPR
1570 ? !is_positive_overflow_infinity (val2)
1571 : is_negative_overflow_infinity (val2)))
1572 /* We only get in here with positive shift count, so the
1573 overflow direction is the same as the sign of val1.
1574 Actually rshift does not overflow at all, but we only
1575 handle the case of shifting overflowed -INF and +INF. */
1576 || (code == RSHIFT_EXPR
1578 /* For division, the only case is -INF / -1 = +INF. */
1579 || code == TRUNC_DIV_EXPR
1580 || code == FLOOR_DIV_EXPR
1581 || code == CEIL_DIV_EXPR
1582 || code == EXACT_DIV_EXPR
1583 || code == ROUND_DIV_EXPR)
1584 return (needs_overflow_infinity (TREE_TYPE (res))
1585 ? positive_overflow_infinity (TREE_TYPE (res))
1586 : TYPE_MAX_VALUE (TREE_TYPE (res)));
1588 return (needs_overflow_infinity (TREE_TYPE (res))
1589 ? negative_overflow_infinity (TREE_TYPE (res))
1590 : TYPE_MIN_VALUE (TREE_TYPE (res)));
1597 /* Extract range information from a binary expression EXPR based on
1598 the ranges of each of its operands and the expression code. */
1601 extract_range_from_binary_expr (value_range_t *vr, tree expr)
1603 enum tree_code code = TREE_CODE (expr);
1604 enum value_range_type type;
1605 tree op0, op1, min, max;
1607 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1608 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1610 /* Not all binary expressions can be applied to ranges in a
1611 meaningful way. Handle only arithmetic operations. */
1612 if (code != PLUS_EXPR
1613 && code != MINUS_EXPR
1614 && code != MULT_EXPR
1615 && code != TRUNC_DIV_EXPR
1616 && code != FLOOR_DIV_EXPR
1617 && code != CEIL_DIV_EXPR
1618 && code != EXACT_DIV_EXPR
1619 && code != ROUND_DIV_EXPR
1620 && code != RSHIFT_EXPR
1623 && code != BIT_AND_EXPR
1624 && code != TRUTH_ANDIF_EXPR
1625 && code != TRUTH_ORIF_EXPR
1626 && code != TRUTH_AND_EXPR
1627 && code != TRUTH_OR_EXPR)
1629 set_value_range_to_varying (vr);
1633 /* Get value ranges for each operand. For constant operands, create
1634 a new value range with the operand to simplify processing. */
1635 op0 = TREE_OPERAND (expr, 0);
1636 if (TREE_CODE (op0) == SSA_NAME)
1637 vr0 = *(get_value_range (op0));
1638 else if (is_gimple_min_invariant (op0))
1639 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1641 set_value_range_to_varying (&vr0);
1643 op1 = TREE_OPERAND (expr, 1);
1644 if (TREE_CODE (op1) == SSA_NAME)
1645 vr1 = *(get_value_range (op1));
1646 else if (is_gimple_min_invariant (op1))
1647 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1649 set_value_range_to_varying (&vr1);
1651 /* If either range is UNDEFINED, so is the result. */
1652 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1654 set_value_range_to_undefined (vr);
1658 /* The type of the resulting value range defaults to VR0.TYPE. */
1661 /* Refuse to operate on VARYING ranges, ranges of different kinds
1662 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1663 because we may be able to derive a useful range even if one of
1664 the operands is VR_VARYING or symbolic range. TODO, we may be
1665 able to derive anti-ranges in some cases. */
1666 if (code != BIT_AND_EXPR
1667 && code != TRUTH_AND_EXPR
1668 && code != TRUTH_OR_EXPR
1669 && (vr0.type == VR_VARYING
1670 || vr1.type == VR_VARYING
1671 || vr0.type != vr1.type
1672 || symbolic_range_p (&vr0)
1673 || symbolic_range_p (&vr1)))
1675 set_value_range_to_varying (vr);
1679 /* Now evaluate the expression to determine the new range. */
1680 if (POINTER_TYPE_P (TREE_TYPE (expr))
1681 || POINTER_TYPE_P (TREE_TYPE (op0))
1682 || POINTER_TYPE_P (TREE_TYPE (op1)))
1684 /* For pointer types, we are really only interested in asserting
1685 whether the expression evaluates to non-NULL. FIXME, we used
1686 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1687 ivopts is generating expressions with pointer multiplication
1689 if (code == PLUS_EXPR)
1691 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1692 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1693 else if (range_is_null (&vr0) && range_is_null (&vr1))
1694 set_value_range_to_null (vr, TREE_TYPE (expr));
1696 set_value_range_to_varying (vr);
1700 /* Subtracting from a pointer, may yield 0, so just drop the
1701 resulting range to varying. */
1702 set_value_range_to_varying (vr);
1708 /* For integer ranges, apply the operation to each end of the
1709 range and see what we end up with. */
1710 if (code == TRUTH_ANDIF_EXPR
1711 || code == TRUTH_ORIF_EXPR
1712 || code == TRUTH_AND_EXPR
1713 || code == TRUTH_OR_EXPR)
1715 /* If one of the operands is zero, we know that the whole
1716 expression evaluates zero. */
1717 if (code == TRUTH_AND_EXPR
1718 && ((vr0.type == VR_RANGE
1719 && integer_zerop (vr0.min)
1720 && integer_zerop (vr0.max))
1721 || (vr1.type == VR_RANGE
1722 && integer_zerop (vr1.min)
1723 && integer_zerop (vr1.max))))
1726 min = max = build_int_cst (TREE_TYPE (expr), 0);
1728 /* If one of the operands is one, we know that the whole
1729 expression evaluates one. */
1730 else if (code == TRUTH_OR_EXPR
1731 && ((vr0.type == VR_RANGE
1732 && integer_onep (vr0.min)
1733 && integer_onep (vr0.max))
1734 || (vr1.type == VR_RANGE
1735 && integer_onep (vr1.min)
1736 && integer_onep (vr1.max))))
1739 min = max = build_int_cst (TREE_TYPE (expr), 1);
1741 else if (vr0.type != VR_VARYING
1742 && vr1.type != VR_VARYING
1743 && vr0.type == vr1.type
1744 && !symbolic_range_p (&vr0)
1745 && !overflow_infinity_range_p (&vr0)
1746 && !symbolic_range_p (&vr1)
1747 && !overflow_infinity_range_p (&vr1))
1749 /* Boolean expressions cannot be folded with int_const_binop. */
1750 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1751 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1755 /* The result of a TRUTH_*_EXPR is always true or false. */
1756 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
1760 else if (code == PLUS_EXPR
1762 || code == MAX_EXPR)
1764 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1765 VR_VARYING. It would take more effort to compute a precise
1766 range for such a case. For example, if we have op0 == 1 and
1767 op1 == -1 with their ranges both being ~[0,0], we would have
1768 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1769 Note that we are guaranteed to have vr0.type == vr1.type at
1771 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1773 set_value_range_to_varying (vr);
1777 /* For operations that make the resulting range directly
1778 proportional to the original ranges, apply the operation to
1779 the same end of each range. */
1780 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1781 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1783 else if (code == MULT_EXPR
1784 || code == TRUNC_DIV_EXPR
1785 || code == FLOOR_DIV_EXPR
1786 || code == CEIL_DIV_EXPR
1787 || code == EXACT_DIV_EXPR
1788 || code == ROUND_DIV_EXPR
1789 || code == RSHIFT_EXPR)
1795 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1796 drop to VR_VARYING. It would take more effort to compute a
1797 precise range for such a case. For example, if we have
1798 op0 == 65536 and op1 == 65536 with their ranges both being
1799 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1800 we cannot claim that the product is in ~[0,0]. Note that we
1801 are guaranteed to have vr0.type == vr1.type at this
1803 if (code == MULT_EXPR
1804 && vr0.type == VR_ANTI_RANGE
1805 && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0)))
1807 set_value_range_to_varying (vr);
1811 /* If we have a RSHIFT_EXPR with a possibly negative shift
1812 count or an anti-range shift count drop to VR_VARYING.
1813 We currently cannot handle the overflow cases correctly. */
1814 if (code == RSHIFT_EXPR
1815 && (vr1.type == VR_ANTI_RANGE
1816 || !vrp_expr_computes_nonnegative (op1, &sop)))
1818 set_value_range_to_varying (vr);
1822 /* Multiplications and divisions are a bit tricky to handle,
1823 depending on the mix of signs we have in the two ranges, we
1824 need to operate on different values to get the minimum and
1825 maximum values for the new range. One approach is to figure
1826 out all the variations of range combinations and do the
1829 However, this involves several calls to compare_values and it
1830 is pretty convoluted. It's simpler to do the 4 operations
1831 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1832 MAX1) and then figure the smallest and largest values to form
1835 /* Divisions by zero result in a VARYING value. */
1836 if ((code != MULT_EXPR
1837 && code != RSHIFT_EXPR)
1838 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1840 set_value_range_to_varying (vr);
1844 /* Compute the 4 cross operations. */
1846 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1847 if (val[0] == NULL_TREE)
1850 if (vr1.max == vr1.min)
1854 val[1] = vrp_int_const_binop (code, vr0.min, vr1.max);
1855 if (val[1] == NULL_TREE)
1859 if (vr0.max == vr0.min)
1863 val[2] = vrp_int_const_binop (code, vr0.max, vr1.min);
1864 if (val[2] == NULL_TREE)
1868 if (vr0.min == vr0.max || vr1.min == vr1.max)
1872 val[3] = vrp_int_const_binop (code, vr0.max, vr1.max);
1873 if (val[3] == NULL_TREE)
1879 set_value_range_to_varying (vr);
1883 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1887 for (i = 1; i < 4; i++)
1889 if (!is_gimple_min_invariant (min)
1890 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
1891 || !is_gimple_min_invariant (max)
1892 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
1897 if (!is_gimple_min_invariant (val[i])
1898 || (TREE_OVERFLOW (val[i])
1899 && !is_overflow_infinity (val[i])))
1901 /* If we found an overflowed value, set MIN and MAX
1902 to it so that we set the resulting range to
1908 if (compare_values (val[i], min) == -1)
1911 if (compare_values (val[i], max) == 1)
1916 else if (code == MINUS_EXPR)
1918 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1919 VR_VARYING. It would take more effort to compute a precise
1920 range for such a case. For example, if we have op0 == 1 and
1921 op1 == 1 with their ranges both being ~[0,0], we would have
1922 op0 - op1 == 0, so we cannot claim that the difference is in
1923 ~[0,0]. Note that we are guaranteed to have
1924 vr0.type == vr1.type at this point. */
1925 if (vr0.type == VR_ANTI_RANGE)
1927 set_value_range_to_varying (vr);
1931 /* For MINUS_EXPR, apply the operation to the opposite ends of
1933 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1934 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1936 else if (code == BIT_AND_EXPR)
1938 if (vr0.type == VR_RANGE
1939 && vr0.min == vr0.max
1940 && TREE_CODE (vr0.max) == INTEGER_CST
1941 && !TREE_OVERFLOW (vr0.max)
1942 && tree_int_cst_sgn (vr0.max) >= 0)
1944 min = build_int_cst (TREE_TYPE (expr), 0);
1947 else if (vr1.type == VR_RANGE
1948 && vr1.min == vr1.max
1949 && TREE_CODE (vr1.max) == INTEGER_CST
1950 && !TREE_OVERFLOW (vr1.max)
1951 && tree_int_cst_sgn (vr1.max) >= 0)
1954 min = build_int_cst (TREE_TYPE (expr), 0);
1959 set_value_range_to_varying (vr);
1966 /* If either MIN or MAX overflowed, then set the resulting range to
1967 VARYING. But we do accept an overflow infinity
1969 if (min == NULL_TREE
1970 || !is_gimple_min_invariant (min)
1971 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
1973 || !is_gimple_min_invariant (max)
1974 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
1976 set_value_range_to_varying (vr);
1980 if ((min == TYPE_MIN_VALUE (TREE_TYPE (min))
1981 || is_negative_overflow_infinity (min))
1982 && (max == TYPE_MAX_VALUE (TREE_TYPE (max))
1983 || is_positive_overflow_infinity (max)))
1985 set_value_range_to_varying (vr);
1989 cmp = compare_values (min, max);
1990 if (cmp == -2 || cmp == 1)
1992 /* If the new range has its limits swapped around (MIN > MAX),
1993 then the operation caused one of them to wrap around, mark
1994 the new range VARYING. */
1995 set_value_range_to_varying (vr);
1998 set_value_range (vr, type, min, max, NULL);
2002 /* Extract range information from a unary expression EXPR based on
2003 the range of its operand and the expression code. */
2006 extract_range_from_unary_expr (value_range_t *vr, tree expr)
2008 enum tree_code code = TREE_CODE (expr);
2011 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2013 /* Refuse to operate on certain unary expressions for which we
2014 cannot easily determine a resulting range. */
2015 if (code == FIX_TRUNC_EXPR
2016 || code == FLOAT_EXPR
2017 || code == BIT_NOT_EXPR
2018 || code == NON_LVALUE_EXPR
2019 || code == CONJ_EXPR)
2021 set_value_range_to_varying (vr);
2025 /* Get value ranges for the operand. For constant operands, create
2026 a new value range with the operand to simplify processing. */
2027 op0 = TREE_OPERAND (expr, 0);
2028 if (TREE_CODE (op0) == SSA_NAME)
2029 vr0 = *(get_value_range (op0));
2030 else if (is_gimple_min_invariant (op0))
2031 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
2033 set_value_range_to_varying (&vr0);
2035 /* If VR0 is UNDEFINED, so is the result. */
2036 if (vr0.type == VR_UNDEFINED)
2038 set_value_range_to_undefined (vr);
2042 /* Refuse to operate on symbolic ranges, or if neither operand is
2043 a pointer or integral type. */
2044 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0))
2045 && !POINTER_TYPE_P (TREE_TYPE (op0)))
2046 || (vr0.type != VR_VARYING
2047 && symbolic_range_p (&vr0)))
2049 set_value_range_to_varying (vr);
2053 /* If the expression involves pointers, we are only interested in
2054 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
2055 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
2060 if (range_is_nonnull (&vr0)
2061 || (tree_expr_nonzero_warnv_p (expr, &sop)
2063 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
2064 else if (range_is_null (&vr0))
2065 set_value_range_to_null (vr, TREE_TYPE (expr));
2067 set_value_range_to_varying (vr);
2072 /* Handle unary expressions on integer ranges. */
2073 if (code == NOP_EXPR || code == CONVERT_EXPR)
2075 tree inner_type = TREE_TYPE (op0);
2076 tree outer_type = TREE_TYPE (expr);
2078 /* If VR0 represents a simple range, then try to convert
2079 the min and max values for the range to the same type
2080 as OUTER_TYPE. If the results compare equal to VR0's
2081 min and max values and the new min is still less than
2082 or equal to the new max, then we can safely use the newly
2083 computed range for EXPR. This allows us to compute
2084 accurate ranges through many casts. */
2085 if ((vr0.type == VR_RANGE
2086 && !overflow_infinity_range_p (&vr0))
2087 || (vr0.type == VR_VARYING
2088 && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type)))
2090 tree new_min, new_max, orig_min, orig_max;
2092 /* Convert the input operand min/max to OUTER_TYPE. If
2093 the input has no range information, then use the min/max
2094 for the input's type. */
2095 if (vr0.type == VR_RANGE)
2102 orig_min = TYPE_MIN_VALUE (inner_type);
2103 orig_max = TYPE_MAX_VALUE (inner_type);
2106 new_min = fold_convert (outer_type, orig_min);
2107 new_max = fold_convert (outer_type, orig_max);
2109 /* Verify the new min/max values are gimple values and
2110 that they compare equal to the original input's
2112 if (is_gimple_val (new_min)
2113 && is_gimple_val (new_max)
2114 && tree_int_cst_equal (new_min, orig_min)
2115 && tree_int_cst_equal (new_max, orig_max)
2116 && (cmp = compare_values (new_min, new_max)) <= 0
2119 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
2124 /* When converting types of different sizes, set the result to
2125 VARYING. Things like sign extensions and precision loss may
2126 change the range. For instance, if x_3 is of type 'long long
2127 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
2128 is impossible to know at compile time whether y_5 will be
2130 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
2131 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
2133 set_value_range_to_varying (vr);
2138 /* Conversion of a VR_VARYING value to a wider type can result
2139 in a usable range. So wait until after we've handled conversions
2140 before dropping the result to VR_VARYING if we had a source
2141 operand that is VR_VARYING. */
2142 if (vr0.type == VR_VARYING)
2144 set_value_range_to_varying (vr);
2148 /* Apply the operation to each end of the range and see what we end
2150 if (code == NEGATE_EXPR
2151 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
2153 /* NEGATE_EXPR flips the range around. We need to treat
2154 TYPE_MIN_VALUE specially. */
2155 if (is_positive_overflow_infinity (vr0.max))
2156 min = negative_overflow_infinity (TREE_TYPE (expr));
2157 else if (is_negative_overflow_infinity (vr0.max))
2158 min = positive_overflow_infinity (TREE_TYPE (expr));
2159 else if (vr0.max != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2160 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2161 else if (needs_overflow_infinity (TREE_TYPE (expr)))
2163 if (supports_overflow_infinity (TREE_TYPE (expr)))
2164 min = positive_overflow_infinity (TREE_TYPE (expr));
2167 set_value_range_to_varying (vr);
2172 min = TYPE_MIN_VALUE (TREE_TYPE (expr));
2174 if (is_positive_overflow_infinity (vr0.min))
2175 max = negative_overflow_infinity (TREE_TYPE (expr));
2176 else if (is_negative_overflow_infinity (vr0.min))
2177 max = positive_overflow_infinity (TREE_TYPE (expr));
2178 else if (vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2179 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2180 else if (needs_overflow_infinity (TREE_TYPE (expr)))
2182 if (supports_overflow_infinity (TREE_TYPE (expr)))
2183 max = positive_overflow_infinity (TREE_TYPE (expr));
2186 set_value_range_to_varying (vr);
2191 max = TYPE_MIN_VALUE (TREE_TYPE (expr));
2193 else if (code == NEGATE_EXPR
2194 && TYPE_UNSIGNED (TREE_TYPE (expr)))
2196 if (!range_includes_zero_p (&vr0))
2198 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2199 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2203 if (range_is_null (&vr0))
2204 set_value_range_to_null (vr, TREE_TYPE (expr));
2206 set_value_range_to_varying (vr);
2210 else if (code == ABS_EXPR
2211 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
2213 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
2215 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (expr))
2216 && ((vr0.type == VR_RANGE
2217 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
2218 || (vr0.type == VR_ANTI_RANGE
2219 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
2220 && !range_includes_zero_p (&vr0))))
2222 set_value_range_to_varying (vr);
2226 /* ABS_EXPR may flip the range around, if the original range
2227 included negative values. */
2228 if (is_overflow_infinity (vr0.min))
2229 min = positive_overflow_infinity (TREE_TYPE (expr));
2230 else if (vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2231 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2232 else if (!needs_overflow_infinity (TREE_TYPE (expr)))
2233 min = TYPE_MAX_VALUE (TREE_TYPE (expr));
2234 else if (supports_overflow_infinity (TREE_TYPE (expr)))
2235 min = positive_overflow_infinity (TREE_TYPE (expr));
2238 set_value_range_to_varying (vr);
2242 if (is_overflow_infinity (vr0.max))
2243 max = positive_overflow_infinity (TREE_TYPE (expr));
2244 else if (vr0.max != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2245 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2246 else if (!needs_overflow_infinity (TREE_TYPE (expr)))
2247 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
2248 else if (supports_overflow_infinity (TREE_TYPE (expr)))
2249 max = positive_overflow_infinity (TREE_TYPE (expr));
2252 set_value_range_to_varying (vr);
2256 cmp = compare_values (min, max);
2258 /* If a VR_ANTI_RANGEs contains zero, then we have
2259 ~[-INF, min(MIN, MAX)]. */
2260 if (vr0.type == VR_ANTI_RANGE)
2262 if (range_includes_zero_p (&vr0))
2264 /* Take the lower of the two values. */
2268 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
2269 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
2270 flag_wrapv is set and the original anti-range doesn't include
2271 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
2272 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr)))
2274 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
2276 min = (vr0.min != type_min_value
2277 ? int_const_binop (PLUS_EXPR, type_min_value,
2278 integer_one_node, 0)
2283 if (overflow_infinity_range_p (&vr0))
2284 min = negative_overflow_infinity (TREE_TYPE (expr));
2286 min = TYPE_MIN_VALUE (TREE_TYPE (expr));
2291 /* All else has failed, so create the range [0, INF], even for
2292 flag_wrapv since TYPE_MIN_VALUE is in the original
2294 vr0.type = VR_RANGE;
2295 min = build_int_cst (TREE_TYPE (expr), 0);
2296 if (needs_overflow_infinity (TREE_TYPE (expr)))
2298 if (supports_overflow_infinity (TREE_TYPE (expr)))
2299 max = positive_overflow_infinity (TREE_TYPE (expr));
2302 set_value_range_to_varying (vr);
2307 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
2311 /* If the range contains zero then we know that the minimum value in the
2312 range will be zero. */
2313 else if (range_includes_zero_p (&vr0))
2317 min = build_int_cst (TREE_TYPE (expr), 0);
2321 /* If the range was reversed, swap MIN and MAX. */
2332 /* Otherwise, operate on each end of the range. */
2333 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2334 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2336 if (needs_overflow_infinity (TREE_TYPE (expr)))
2338 gcc_assert (code != NEGATE_EXPR && code != ABS_EXPR);
2339 if (is_overflow_infinity (vr0.min))
2341 else if (TREE_OVERFLOW (min))
2343 if (supports_overflow_infinity (TREE_TYPE (expr)))
2344 min = (tree_int_cst_sgn (min) >= 0
2345 ? positive_overflow_infinity (TREE_TYPE (min))
2346 : negative_overflow_infinity (TREE_TYPE (min)));
2349 set_value_range_to_varying (vr);
2354 if (is_overflow_infinity (vr0.max))
2356 else if (TREE_OVERFLOW (max))
2358 if (supports_overflow_infinity (TREE_TYPE (expr)))
2359 max = (tree_int_cst_sgn (max) >= 0
2360 ? positive_overflow_infinity (TREE_TYPE (max))
2361 : negative_overflow_infinity (TREE_TYPE (max)));
2364 set_value_range_to_varying (vr);
2371 cmp = compare_values (min, max);
2372 if (cmp == -2 || cmp == 1)
2374 /* If the new range has its limits swapped around (MIN > MAX),
2375 then the operation caused one of them to wrap around, mark
2376 the new range VARYING. */
2377 set_value_range_to_varying (vr);
2380 set_value_range (vr, vr0.type, min, max, NULL);
2384 /* Extract range information from a conditional expression EXPR based on
2385 the ranges of each of its operands and the expression code. */
2388 extract_range_from_cond_expr (value_range_t *vr, tree expr)
2391 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2392 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2394 /* Get value ranges for each operand. For constant operands, create
2395 a new value range with the operand to simplify processing. */
2396 op0 = COND_EXPR_THEN (expr);
2397 if (TREE_CODE (op0) == SSA_NAME)
2398 vr0 = *(get_value_range (op0));
2399 else if (is_gimple_min_invariant (op0))
2400 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
2402 set_value_range_to_varying (&vr0);
2404 op1 = COND_EXPR_ELSE (expr);
2405 if (TREE_CODE (op1) == SSA_NAME)
2406 vr1 = *(get_value_range (op1));
2407 else if (is_gimple_min_invariant (op1))
2408 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
2410 set_value_range_to_varying (&vr1);
2412 /* The resulting value range is the union of the operand ranges */
2413 vrp_meet (&vr0, &vr1);
2414 copy_value_range (vr, &vr0);
2418 /* Extract range information from a comparison expression EXPR based
2419 on the range of its operand and the expression code. */
2422 extract_range_from_comparison (value_range_t *vr, tree expr)
2425 tree val = vrp_evaluate_conditional_warnv (expr, false, &sop);
2427 /* A disadvantage of using a special infinity as an overflow
2428 representation is that we lose the ability to record overflow
2429 when we don't have an infinity. So we have to ignore a result
2430 which relies on overflow. */
2432 if (val && !is_overflow_infinity (val) && !sop)
2434 /* Since this expression was found on the RHS of an assignment,
2435 its type may be different from _Bool. Convert VAL to EXPR's
2437 val = fold_convert (TREE_TYPE (expr), val);
2438 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
2441 /* The result of a comparison is always true or false. */
2442 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
2446 /* Try to compute a useful range out of expression EXPR and store it
2450 extract_range_from_expr (value_range_t *vr, tree expr)
2452 enum tree_code code = TREE_CODE (expr);
2454 if (code == ASSERT_EXPR)
2455 extract_range_from_assert (vr, expr);
2456 else if (code == SSA_NAME)
2457 extract_range_from_ssa_name (vr, expr);
2458 else if (TREE_CODE_CLASS (code) == tcc_binary
2459 || code == TRUTH_ANDIF_EXPR
2460 || code == TRUTH_ORIF_EXPR
2461 || code == TRUTH_AND_EXPR
2462 || code == TRUTH_OR_EXPR
2463 || code == TRUTH_XOR_EXPR)
2464 extract_range_from_binary_expr (vr, expr);
2465 else if (TREE_CODE_CLASS (code) == tcc_unary)
2466 extract_range_from_unary_expr (vr, expr);
2467 else if (code == COND_EXPR)
2468 extract_range_from_cond_expr (vr, expr);
2469 else if (TREE_CODE_CLASS (code) == tcc_comparison)
2470 extract_range_from_comparison (vr, expr);
2471 else if (is_gimple_min_invariant (expr))
2472 set_value_range (vr, VR_RANGE, expr, expr, NULL);
2474 set_value_range_to_varying (vr);
2476 /* If we got a varying range from the tests above, try a final
2477 time to derive a nonnegative or nonzero range. This time
2478 relying primarily on generic routines in fold in conjunction
2480 if (vr->type == VR_VARYING)
2484 if (INTEGRAL_TYPE_P (TREE_TYPE (expr))
2485 && vrp_expr_computes_nonnegative (expr, &sop))
2486 set_value_range_to_nonnegative (vr, TREE_TYPE (expr),
2487 sop || is_overflow_infinity (expr));
2488 else if (vrp_expr_computes_nonzero (expr, &sop)
2490 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
2494 /* Given a range VR, a LOOP and a variable VAR, determine whether it
2495 would be profitable to adjust VR using scalar evolution information
2496 for VAR. If so, update VR with the new limits. */
2499 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
2502 tree init, step, chrec, tmin, tmax, min, max, type;
2503 enum ev_direction dir;
2505 /* TODO. Don't adjust anti-ranges. An anti-range may provide
2506 better opportunities than a regular range, but I'm not sure. */
2507 if (vr->type == VR_ANTI_RANGE)
2510 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
2511 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
2514 init = initial_condition_in_loop_num (chrec, loop->num);
2515 step = evolution_part_in_loop_num (chrec, loop->num);
2517 /* If STEP is symbolic, we can't know whether INIT will be the
2518 minimum or maximum value in the range. Also, unless INIT is
2519 a simple expression, compare_values and possibly other functions
2520 in tree-vrp won't be able to handle it. */
2521 if (step == NULL_TREE
2522 || !is_gimple_min_invariant (step)
2523 || !valid_value_p (init))
2526 dir = scev_direction (chrec);
2527 if (/* Do not adjust ranges if we do not know whether the iv increases
2528 or decreases, ... */
2529 dir == EV_DIR_UNKNOWN
2530 /* ... or if it may wrap. */
2531 || scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec),
2535 /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of
2536 negative_overflow_infinity and positive_overflow_infinity,
2537 because we have concluded that the loop probably does not
2540 type = TREE_TYPE (var);
2541 if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type))
2542 tmin = lower_bound_in_type (type, type);
2544 tmin = TYPE_MIN_VALUE (type);
2545 if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type))
2546 tmax = upper_bound_in_type (type, type);
2548 tmax = TYPE_MAX_VALUE (type);
2550 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2555 /* For VARYING or UNDEFINED ranges, just about anything we get
2556 from scalar evolutions should be better. */
2558 if (dir == EV_DIR_DECREASES)
2563 /* If we would create an invalid range, then just assume we
2564 know absolutely nothing. This may be over-conservative,
2565 but it's clearly safe, and should happen only in unreachable
2566 parts of code, or for invalid programs. */
2567 if (compare_values (min, max) == 1)
2570 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2572 else if (vr->type == VR_RANGE)
2577 if (dir == EV_DIR_DECREASES)
2579 /* INIT is the maximum value. If INIT is lower than VR->MAX
2580 but no smaller than VR->MIN, set VR->MAX to INIT. */
2581 if (compare_values (init, max) == -1)
2585 /* If we just created an invalid range with the minimum
2586 greater than the maximum, we fail conservatively.
2587 This should happen only in unreachable
2588 parts of code, or for invalid programs. */
2589 if (compare_values (min, max) == 1)
2595 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2596 if (compare_values (init, min) == 1)
2600 /* Again, avoid creating invalid range by failing. */
2601 if (compare_values (min, max) == 1)
2606 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2611 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2613 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2614 all the values in the ranges.
2616 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2618 - Return NULL_TREE if it is not always possible to determine the
2619 value of the comparison.
2621 Also set *STRICT_OVERFLOW_P to indicate whether a range with an
2622 overflow infinity was used in the test. */
2626 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1,
2627 bool *strict_overflow_p)
2629 /* VARYING or UNDEFINED ranges cannot be compared. */
2630 if (vr0->type == VR_VARYING
2631 || vr0->type == VR_UNDEFINED
2632 || vr1->type == VR_VARYING
2633 || vr1->type == VR_UNDEFINED)
2636 /* Anti-ranges need to be handled separately. */
2637 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
2639 /* If both are anti-ranges, then we cannot compute any
2641 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
2644 /* These comparisons are never statically computable. */
2651 /* Equality can be computed only between a range and an
2652 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2653 if (vr0->type == VR_RANGE)
2655 /* To simplify processing, make VR0 the anti-range. */
2656 value_range_t *tmp = vr0;
2661 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
2663 if (compare_values_warnv (vr0->min, vr1->min, strict_overflow_p) == 0
2664 && compare_values_warnv (vr0->max, vr1->max, strict_overflow_p) == 0)
2665 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2670 if (!usable_range_p (vr0, strict_overflow_p)
2671 || !usable_range_p (vr1, strict_overflow_p))
2674 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2675 operands around and change the comparison code. */
2676 if (comp == GT_EXPR || comp == GE_EXPR)
2679 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
2685 if (comp == EQ_EXPR)
2687 /* Equality may only be computed if both ranges represent
2688 exactly one value. */
2689 if (compare_values_warnv (vr0->min, vr0->max, strict_overflow_p) == 0
2690 && compare_values_warnv (vr1->min, vr1->max, strict_overflow_p) == 0)
2692 int cmp_min = compare_values_warnv (vr0->min, vr1->min,
2694 int cmp_max = compare_values_warnv (vr0->max, vr1->max,
2696 if (cmp_min == 0 && cmp_max == 0)
2697 return boolean_true_node;
2698 else if (cmp_min != -2 && cmp_max != -2)
2699 return boolean_false_node;
2701 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2702 else if (compare_values_warnv (vr0->min, vr1->max,
2703 strict_overflow_p) == 1
2704 || compare_values_warnv (vr1->min, vr0->max,
2705 strict_overflow_p) == 1)
2706 return boolean_false_node;
2710 else if (comp == NE_EXPR)
2714 /* If VR0 is completely to the left or completely to the right
2715 of VR1, they are always different. Notice that we need to
2716 make sure that both comparisons yield similar results to
2717 avoid comparing values that cannot be compared at
2719 cmp1 = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
2720 cmp2 = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
2721 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
2722 return boolean_true_node;
2724 /* If VR0 and VR1 represent a single value and are identical,
2726 else if (compare_values_warnv (vr0->min, vr0->max,
2727 strict_overflow_p) == 0
2728 && compare_values_warnv (vr1->min, vr1->max,
2729 strict_overflow_p) == 0
2730 && compare_values_warnv (vr0->min, vr1->min,
2731 strict_overflow_p) == 0
2732 && compare_values_warnv (vr0->max, vr1->max,
2733 strict_overflow_p) == 0)
2734 return boolean_false_node;
2736 /* Otherwise, they may or may not be different. */
2740 else if (comp == LT_EXPR || comp == LE_EXPR)
2744 /* If VR0 is to the left of VR1, return true. */
2745 tst = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
2746 if ((comp == LT_EXPR && tst == -1)
2747 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2749 if (overflow_infinity_range_p (vr0)
2750 || overflow_infinity_range_p (vr1))
2751 *strict_overflow_p = true;
2752 return boolean_true_node;
2755 /* If VR0 is to the right of VR1, return false. */
2756 tst = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
2757 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2758 || (comp == LE_EXPR && tst == 1))
2760 if (overflow_infinity_range_p (vr0)
2761 || overflow_infinity_range_p (vr1))
2762 *strict_overflow_p = true;
2763 return boolean_false_node;
2766 /* Otherwise, we don't know. */
2774 /* Given a value range VR, a value VAL and a comparison code COMP, return
2775 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2776 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2777 always returns false. Return NULL_TREE if it is not always
2778 possible to determine the value of the comparison. Also set
2779 *STRICT_OVERFLOW_P to indicate whether a range with an overflow
2780 infinity was used in the test. */
2783 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val,
2784 bool *strict_overflow_p)
2786 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2789 /* Anti-ranges need to be handled separately. */
2790 if (vr->type == VR_ANTI_RANGE)
2792 /* For anti-ranges, the only predicates that we can compute at
2793 compile time are equality and inequality. */
2800 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2801 if (value_inside_range (val, vr) == 1)
2802 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2807 if (!usable_range_p (vr, strict_overflow_p))
2810 if (comp == EQ_EXPR)
2812 /* EQ_EXPR may only be computed if VR represents exactly
2814 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0)
2816 int cmp = compare_values_warnv (vr->min, val, strict_overflow_p);
2818 return boolean_true_node;
2819 else if (cmp == -1 || cmp == 1 || cmp == 2)
2820 return boolean_false_node;
2822 else if (compare_values_warnv (val, vr->min, strict_overflow_p) == -1
2823 || compare_values_warnv (vr->max, val, strict_overflow_p) == -1)
2824 return boolean_false_node;
2828 else if (comp == NE_EXPR)
2830 /* If VAL is not inside VR, then they are always different. */
2831 if (compare_values_warnv (vr->max, val, strict_overflow_p) == -1
2832 || compare_values_warnv (vr->min, val, strict_overflow_p) == 1)
2833 return boolean_true_node;
2835 /* If VR represents exactly one value equal to VAL, then return
2837 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0
2838 && compare_values_warnv (vr->min, val, strict_overflow_p) == 0)
2839 return boolean_false_node;
2841 /* Otherwise, they may or may not be different. */
2844 else if (comp == LT_EXPR || comp == LE_EXPR)
2848 /* If VR is to the left of VAL, return true. */
2849 tst = compare_values_warnv (vr->max, val, strict_overflow_p);
2850 if ((comp == LT_EXPR && tst == -1)
2851 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2853 if (overflow_infinity_range_p (vr))
2854 *strict_overflow_p = true;
2855 return boolean_true_node;
2858 /* If VR is to the right of VAL, return false. */
2859 tst = compare_values_warnv (vr->min, val, strict_overflow_p);
2860 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2861 || (comp == LE_EXPR && tst == 1))
2863 if (overflow_infinity_range_p (vr))
2864 *strict_overflow_p = true;
2865 return boolean_false_node;
2868 /* Otherwise, we don't know. */
2871 else if (comp == GT_EXPR || comp == GE_EXPR)
2875 /* If VR is to the right of VAL, return true. */
2876 tst = compare_values_warnv (vr->min, val, strict_overflow_p);
2877 if ((comp == GT_EXPR && tst == 1)
2878 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
2880 if (overflow_infinity_range_p (vr))
2881 *strict_overflow_p = true;
2882 return boolean_true_node;
2885 /* If VR is to the left of VAL, return false. */
2886 tst = compare_values_warnv (vr->max, val, strict_overflow_p);
2887 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
2888 || (comp == GE_EXPR && tst == -1))
2890 if (overflow_infinity_range_p (vr))
2891 *strict_overflow_p = true;
2892 return boolean_false_node;
2895 /* Otherwise, we don't know. */
2903 /* Debugging dumps. */
2905 void dump_value_range (FILE *, value_range_t *);
2906 void debug_value_range (value_range_t *);
2907 void dump_all_value_ranges (FILE *);
2908 void debug_all_value_ranges (void);
2909 void dump_vr_equiv (FILE *, bitmap);
2910 void debug_vr_equiv (bitmap);
2913 /* Dump value range VR to FILE. */
2916 dump_value_range (FILE *file, value_range_t *vr)
2919 fprintf (file, "[]");
2920 else if (vr->type == VR_UNDEFINED)
2921 fprintf (file, "UNDEFINED");
2922 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
2924 tree type = TREE_TYPE (vr->min);
2926 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
2928 if (INTEGRAL_TYPE_P (type)
2929 && !TYPE_UNSIGNED (type)
2930 && vr->min == TYPE_MIN_VALUE (type))
2931 fprintf (file, "-INF");
2932 else if (needs_overflow_infinity (type)
2933 && is_negative_overflow_infinity (vr->min))
2934 fprintf (file, "-INF(OVF)");
2936 print_generic_expr (file, vr->min, 0);
2938 fprintf (file, ", ");
2940 if (INTEGRAL_TYPE_P (type)
2941 && vr->max == TYPE_MAX_VALUE (type))
2942 fprintf (file, "+INF");
2943 else if (needs_overflow_infinity (type)
2944 && is_positive_overflow_infinity (vr->max))
2945 fprintf (file, "+INF(OVF)");
2947 print_generic_expr (file, vr->max, 0);
2949 fprintf (file, "]");
2956 fprintf (file, " EQUIVALENCES: { ");
2958 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
2960 print_generic_expr (file, ssa_name (i), 0);
2961 fprintf (file, " ");
2965 fprintf (file, "} (%u elements)", c);
2968 else if (vr->type == VR_VARYING)
2969 fprintf (file, "VARYING");
2971 fprintf (file, "INVALID RANGE");
2975 /* Dump value range VR to stderr. */
2978 debug_value_range (value_range_t *vr)
2980 dump_value_range (stderr, vr);
2981 fprintf (stderr, "\n");
2985 /* Dump value ranges of all SSA_NAMEs to FILE. */
2988 dump_all_value_ranges (FILE *file)
2992 for (i = 0; i < num_ssa_names; i++)
2996 print_generic_expr (file, ssa_name (i), 0);
2997 fprintf (file, ": ");
2998 dump_value_range (file, vr_value[i]);
2999 fprintf (file, "\n");
3003 fprintf (file, "\n");
3007 /* Dump all value ranges to stderr. */
3010 debug_all_value_ranges (void)
3012 dump_all_value_ranges (stderr);
3016 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
3017 create a new SSA name N and return the assertion assignment
3018 'V = ASSERT_EXPR <V, V OP W>'. */
3021 build_assert_expr_for (tree cond, tree v)
3025 gcc_assert (TREE_CODE (v) == SSA_NAME);
3026 n = duplicate_ssa_name (v, NULL_TREE);
3028 if (COMPARISON_CLASS_P (cond))
3030 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
3031 assertion = build_gimple_modify_stmt (n, a);
3033 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
3035 /* Given !V, build the assignment N = false. */
3036 tree op0 = TREE_OPERAND (cond, 0);
3037 gcc_assert (op0 == v);
3038 assertion = build_gimple_modify_stmt (n, boolean_false_node);
3040 else if (TREE_CODE (cond) == SSA_NAME)
3042 /* Given V, build the assignment N = true. */
3043 gcc_assert (v == cond);
3044 assertion = build_gimple_modify_stmt (n, boolean_true_node);
3049 SSA_NAME_DEF_STMT (n) = assertion;
3051 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
3052 operand of the ASSERT_EXPR. Register the new name and the old one
3053 in the replacement table so that we can fix the SSA web after
3054 adding all the ASSERT_EXPRs. */
3055 register_new_name_mapping (n, v);
3061 /* Return false if EXPR is a predicate expression involving floating
3065 fp_predicate (tree expr)
3067 return (COMPARISON_CLASS_P (expr)
3068 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
3072 /* If the range of values taken by OP can be inferred after STMT executes,
3073 return the comparison code (COMP_CODE_P) and value (VAL_P) that
3074 describes the inferred range. Return true if a range could be
3078 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
3081 *comp_code_p = ERROR_MARK;
3083 /* Do not attempt to infer anything in names that flow through
3085 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
3088 /* Similarly, don't infer anything from statements that may throw
3090 if (tree_could_throw_p (stmt))
3093 /* If STMT is the last statement of a basic block with no
3094 successors, there is no point inferring anything about any of its
3095 operands. We would not be able to find a proper insertion point
3096 for the assertion, anyway. */
3097 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
3100 /* We can only assume that a pointer dereference will yield
3101 non-NULL if -fdelete-null-pointer-checks is enabled. */
3102 if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op)))
3105 unsigned num_uses, num_derefs;
3107 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
3110 *val_p = build_int_cst (TREE_TYPE (op), 0);
3111 *comp_code_p = NE_EXPR;
3120 void dump_asserts_for (FILE *, tree);
3121 void debug_asserts_for (tree);
3122 void dump_all_asserts (FILE *);
3123 void debug_all_asserts (void);
3125 /* Dump all the registered assertions for NAME to FILE. */
3128 dump_asserts_for (FILE *file, tree name)
3132 fprintf (file, "Assertions to be inserted for ");
3133 print_generic_expr (file, name, 0);
3134 fprintf (file, "\n");
3136 loc = asserts_for[SSA_NAME_VERSION (name)];
3139 fprintf (file, "\t");
3140 print_generic_expr (file, bsi_stmt (loc->si), 0);
3141 fprintf (file, "\n\tBB #%d", loc->bb->index);
3144 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
3145 loc->e->dest->index);
3146 dump_edge_info (file, loc->e, 0);
3148 fprintf (file, "\n\tPREDICATE: ");
3149 print_generic_expr (file, name, 0);
3150 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
3151 print_generic_expr (file, loc->val, 0);
3152 fprintf (file, "\n\n");
3156 fprintf (file, "\n");
3160 /* Dump all the registered assertions for NAME to stderr. */
3163 debug_asserts_for (tree name)
3165 dump_asserts_for (stderr, name);
3169 /* Dump all the registered assertions for all the names to FILE. */
3172 dump_all_asserts (FILE *file)
3177 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
3178 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3179 dump_asserts_for (file, ssa_name (i));
3180 fprintf (file, "\n");
3184 /* Dump all the registered assertions for all the names to stderr. */
3187 debug_all_asserts (void)
3189 dump_all_asserts (stderr);
3193 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
3194 'NAME COMP_CODE VAL' at a location that dominates block BB or
3195 E->DEST, then register this location as a possible insertion point
3196 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
3198 BB, E and SI provide the exact insertion point for the new
3199 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
3200 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
3201 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
3202 must not be NULL. */
3205 register_new_assert_for (tree name,
3206 enum tree_code comp_code,
3210 block_stmt_iterator si)
3212 assert_locus_t n, loc, last_loc;
3214 basic_block dest_bb;
3216 #if defined ENABLE_CHECKING
3217 gcc_assert (bb == NULL || e == NULL);
3220 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
3221 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
3224 /* The new assertion A will be inserted at BB or E. We need to
3225 determine if the new location is dominated by a previously
3226 registered location for A. If we are doing an edge insertion,
3227 assume that A will be inserted at E->DEST. Note that this is not
3230 If E is a critical edge, it will be split. But even if E is
3231 split, the new block will dominate the same set of blocks that
3234 The reverse, however, is not true, blocks dominated by E->DEST
3235 will not be dominated by the new block created to split E. So,
3236 if the insertion location is on a critical edge, we will not use
3237 the new location to move another assertion previously registered
3238 at a block dominated by E->DEST. */
3239 dest_bb = (bb) ? bb : e->dest;
3241 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
3242 VAL at a block dominating DEST_BB, then we don't need to insert a new
3243 one. Similarly, if the same assertion already exists at a block
3244 dominated by DEST_BB and the new location is not on a critical
3245 edge, then update the existing location for the assertion (i.e.,
3246 move the assertion up in the dominance tree).
3248 Note, this is implemented as a simple linked list because there
3249 should not be more than a handful of assertions registered per
3250 name. If this becomes a performance problem, a table hashed by
3251 COMP_CODE and VAL could be implemented. */
3252 loc = asserts_for[SSA_NAME_VERSION (name)];
3257 if (loc->comp_code == comp_code
3259 || operand_equal_p (loc->val, val, 0)))
3261 /* If the assertion NAME COMP_CODE VAL has already been
3262 registered at a basic block that dominates DEST_BB, then
3263 we don't need to insert the same assertion again. Note
3264 that we don't check strict dominance here to avoid
3265 replicating the same assertion inside the same basic
3266 block more than once (e.g., when a pointer is
3267 dereferenced several times inside a block).
3269 An exception to this rule are edge insertions. If the
3270 new assertion is to be inserted on edge E, then it will
3271 dominate all the other insertions that we may want to
3272 insert in DEST_BB. So, if we are doing an edge
3273 insertion, don't do this dominance check. */
3275 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
3278 /* Otherwise, if E is not a critical edge and DEST_BB
3279 dominates the existing location for the assertion, move
3280 the assertion up in the dominance tree by updating its
3281 location information. */
3282 if ((e == NULL || !EDGE_CRITICAL_P (e))
3283 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
3292 /* Update the last node of the list and move to the next one. */
3297 /* If we didn't find an assertion already registered for
3298 NAME COMP_CODE VAL, add a new one at the end of the list of
3299 assertions associated with NAME. */
3300 n = XNEW (struct assert_locus_d);
3304 n->comp_code = comp_code;
3311 asserts_for[SSA_NAME_VERSION (name)] = n;
3313 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
3316 /* COND is a predicate which uses NAME. Extract a suitable test code
3317 and value and store them into *CODE_P and *VAL_P so the predicate
3318 is normalized to NAME *CODE_P *VAL_P.
3320 If no extraction was possible, return FALSE, otherwise return TRUE.
3322 If INVERT is true, then we invert the result stored into *CODE_P. */
3325 extract_code_and_val_from_cond (tree name, tree cond, bool invert,
3326 enum tree_code *code_p, tree *val_p)
3328 enum tree_code comp_code;
3331 /* Predicates may be a single SSA name or NAME OP VAL. */
3334 /* If the predicate is a name, it must be NAME, in which
3335 case we create the predicate NAME == true or
3336 NAME == false accordingly. */
3337 comp_code = EQ_EXPR;
3338 val = invert ? boolean_false_node : boolean_true_node;
3342 /* Otherwise, we have a comparison of the form NAME COMP VAL
3343 or VAL COMP NAME. */
3344 if (name == TREE_OPERAND (cond, 1))
3346 /* If the predicate is of the form VAL COMP NAME, flip
3347 COMP around because we need to register NAME as the
3348 first operand in the predicate. */
3349 comp_code = swap_tree_comparison (TREE_CODE (cond));
3350 val = TREE_OPERAND (cond, 0);
3354 /* The comparison is of the form NAME COMP VAL, so the
3355 comparison code remains unchanged. */
3356 comp_code = TREE_CODE (cond);
3357 val = TREE_OPERAND (cond, 1);
3360 /* Invert the comparison code as necessary. */
3362 comp_code = invert_tree_comparison (comp_code, 0);
3364 /* VRP does not handle float types. */
3365 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)))
3368 /* Do not register always-false predicates.
3369 FIXME: this works around a limitation in fold() when dealing with
3370 enumerations. Given 'enum { N1, N2 } x;', fold will not
3371 fold 'if (x > N2)' to 'if (0)'. */
3372 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
3373 && INTEGRAL_TYPE_P (TREE_TYPE (val)))
3375 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
3376 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
3378 if (comp_code == GT_EXPR
3380 || compare_values (val, max) == 0))
3383 if (comp_code == LT_EXPR
3385 || compare_values (val, min) == 0))
3389 *code_p = comp_code;
3394 /* OP is an operand of a truth value expression which is known to have
3395 a particular value. Register any asserts for OP and for any
3396 operands in OP's defining statement.
3398 If CODE is EQ_EXPR, then we want to register OP is zero (false),
3399 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
3402 register_edge_assert_for_1 (tree op, enum tree_code code,
3403 edge e, block_stmt_iterator bsi)
3405 bool retval = false;
3406 tree op_def, rhs, val;
3408 /* We only care about SSA_NAMEs. */
3409 if (TREE_CODE (op) != SSA_NAME)
3412 /* We know that OP will have a zero or nonzero value. If OP is used
3413 more than once go ahead and register an assert for OP.
3415 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
3416 it will always be set for OP (because OP is used in a COND_EXPR in
3418 if (!has_single_use (op))
3420 val = build_int_cst (TREE_TYPE (op), 0);
3421 register_new_assert_for (op, code, val, NULL, e, bsi);
3425 /* Now look at how OP is set. If it's set from a comparison,
3426 a truth operation or some bit operations, then we may be able
3427 to register information about the operands of that assignment. */
3428 op_def = SSA_NAME_DEF_STMT (op);
3429 if (TREE_CODE (op_def) != GIMPLE_MODIFY_STMT)
3432 rhs = GIMPLE_STMT_OPERAND (op_def, 1);
3434 if (COMPARISON_CLASS_P (rhs))
3436 bool invert = (code == EQ_EXPR ? true : false);
3437 tree op0 = TREE_OPERAND (rhs, 0);
3438 tree op1 = TREE_OPERAND (rhs, 1);
3440 /* Conditionally register an assert for each SSA_NAME in the
3442 if (TREE_CODE (op0) == SSA_NAME
3443 && !has_single_use (op0)
3444 && extract_code_and_val_from_cond (op0, rhs,
3445 invert, &code, &val))
3447 register_new_assert_for (op0, code, val, NULL, e, bsi);
3451 /* Similarly for the second operand of the comparison. */
3452 if (TREE_CODE (op1) == SSA_NAME
3453 && !has_single_use (op1)
3454 && extract_code_and_val_from_cond (op1, rhs,
3455 invert, &code, &val))
3457 register_new_assert_for (op1, code, val, NULL, e, bsi);
3461 else if ((code == NE_EXPR
3462 && (TREE_CODE (rhs) == TRUTH_AND_EXPR
3463 || TREE_CODE (rhs) == BIT_AND_EXPR))
3465 && (TREE_CODE (rhs) == TRUTH_OR_EXPR
3466 || TREE_CODE (rhs) == BIT_IOR_EXPR)))
3468 /* Recurse on each operand. */
3469 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3471 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 1),
3474 else if (TREE_CODE (rhs) == TRUTH_NOT_EXPR)
3476 /* Recurse, flipping CODE. */
3477 code = invert_tree_comparison (code, false);
3478 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3481 else if (TREE_CODE (rhs) == SSA_NAME)
3483 /* Recurse through the copy. */
3484 retval |= register_edge_assert_for_1 (rhs, code, e, bsi);
3486 else if (TREE_CODE (rhs) == NOP_EXPR
3487 || TREE_CODE (rhs) == CONVERT_EXPR
3488 || TREE_CODE (rhs) == NON_LVALUE_EXPR)
3490 /* Recurse through the type conversion. */
3491 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3498 /* Try to register an edge assertion for SSA name NAME on edge E for
3499 the condition COND contributing to the conditional jump pointed to by SI.
3500 Return true if an assertion for NAME could be registered. */
3503 register_edge_assert_for (tree name, edge e, block_stmt_iterator si, tree cond)
3506 enum tree_code comp_code;
3507 bool retval = false;
3508 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
3510 /* Do not attempt to infer anything in names that flow through
3512 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
3515 if (!extract_code_and_val_from_cond (name, cond, is_else_edge,
3519 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
3520 reachable from E. */
3521 if (TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
3523 register_new_assert_for (name, comp_code, val, NULL, e, si);
3527 /* If COND is effectively an equality test of an SSA_NAME against
3528 the value zero or one, then we may be able to assert values
3529 for SSA_NAMEs which flow into COND. */
3531 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
3532 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
3533 have nonzero value. */
3534 if (((comp_code == EQ_EXPR && integer_onep (val))
3535 || (comp_code == NE_EXPR && integer_zerop (val))))
3537 tree def_stmt = SSA_NAME_DEF_STMT (name);
3539 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3540 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_AND_EXPR
3541 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_AND_EXPR))
3543 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3544 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3545 retval |= register_edge_assert_for_1 (op0, NE_EXPR, e, si);
3546 retval |= register_edge_assert_for_1 (op1, NE_EXPR, e, si);
3550 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
3551 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
3553 if (((comp_code == EQ_EXPR && integer_zerop (val))
3554 || (comp_code == NE_EXPR && integer_onep (val))))
3556 tree def_stmt = SSA_NAME_DEF_STMT (name);
3558 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3559 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_OR_EXPR
3560 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_IOR_EXPR))
3562 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3563 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3564 retval |= register_edge_assert_for_1 (op0, EQ_EXPR, e, si);
3565 retval |= register_edge_assert_for_1 (op1, EQ_EXPR, e, si);
3573 static bool find_assert_locations (basic_block bb);
3575 /* Determine whether the outgoing edges of BB should receive an
3576 ASSERT_EXPR for each of the operands of BB's LAST statement.
3577 The last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
3579 If any of the sub-graphs rooted at BB have an interesting use of
3580 the predicate operands, an assert location node is added to the
3581 list of assertions for the corresponding operands. */
3584 find_conditional_asserts (basic_block bb, tree last)
3587 block_stmt_iterator bsi;
3593 need_assert = false;
3594 bsi = bsi_for_stmt (last);
3596 /* Look for uses of the operands in each of the sub-graphs
3597 rooted at BB. We need to check each of the outgoing edges
3598 separately, so that we know what kind of ASSERT_EXPR to
3600 FOR_EACH_EDGE (e, ei, bb->succs)
3605 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
3606 Otherwise, when we finish traversing each of the sub-graphs, we
3607 won't know whether the variables were found in the sub-graphs or
3608 if they had been found in a block upstream from BB.
3610 This is actually a bad idea is some cases, particularly jump
3611 threading. Consider a CFG like the following:
3621 Assume that one or more operands in the conditional at the
3622 end of block 0 are used in a conditional in block 2, but not
3623 anywhere in block 1. In this case we will not insert any
3624 assert statements in block 1, which may cause us to miss
3625 opportunities to optimize, particularly for jump threading. */
3626 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3627 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3629 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3630 to determine if any of the operands in the conditional
3631 predicate are used. */
3633 need_assert |= find_assert_locations (e->dest);
3635 /* Register the necessary assertions for each operand in the
3636 conditional predicate. */
3637 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3638 need_assert |= register_edge_assert_for (op, e, bsi,
3639 COND_EXPR_COND (last));
3642 /* Finally, indicate that we have found the operands in the
3644 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3645 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3651 /* Traverse all the statements in block BB looking for statements that
3652 may generate useful assertions for the SSA names in their operand.
3653 If a statement produces a useful assertion A for name N_i, then the
3654 list of assertions already generated for N_i is scanned to
3655 determine if A is actually needed.
3657 If N_i already had the assertion A at a location dominating the
3658 current location, then nothing needs to be done. Otherwise, the
3659 new location for A is recorded instead.
3661 1- For every statement S in BB, all the variables used by S are
3662 added to bitmap FOUND_IN_SUBGRAPH.
3664 2- If statement S uses an operand N in a way that exposes a known
3665 value range for N, then if N was not already generated by an
3666 ASSERT_EXPR, create a new assert location for N. For instance,
3667 if N is a pointer and the statement dereferences it, we can
3668 assume that N is not NULL.
3670 3- COND_EXPRs are a special case of #2. We can derive range
3671 information from the predicate but need to insert different
3672 ASSERT_EXPRs for each of the sub-graphs rooted at the
3673 conditional block. If the last statement of BB is a conditional
3674 expression of the form 'X op Y', then
3676 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
3678 b) If the conditional is the only entry point to the sub-graph
3679 corresponding to the THEN_CLAUSE, recurse into it. On
3680 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
3681 an ASSERT_EXPR is added for the corresponding variable.
3683 c) Repeat step (b) on the ELSE_CLAUSE.
3685 d) Mark X and Y in FOUND_IN_SUBGRAPH.
3694 In this case, an assertion on the THEN clause is useful to
3695 determine that 'a' is always 9 on that edge. However, an assertion
3696 on the ELSE clause would be unnecessary.
3698 4- If BB does not end in a conditional expression, then we recurse
3699 into BB's dominator children.
3701 At the end of the recursive traversal, every SSA name will have a
3702 list of locations where ASSERT_EXPRs should be added. When a new
3703 location for name N is found, it is registered by calling
3704 register_new_assert_for. That function keeps track of all the
3705 registered assertions to prevent adding unnecessary assertions.
3706 For instance, if a pointer P_4 is dereferenced more than once in a
3707 dominator tree, only the location dominating all the dereference of
3708 P_4 will receive an ASSERT_EXPR.
3710 If this function returns true, then it means that there are names
3711 for which we need to generate ASSERT_EXPRs. Those assertions are
3712 inserted by process_assert_insertions.
3714 TODO. Handle SWITCH_EXPR. */
3717 find_assert_locations (basic_block bb)
3719 block_stmt_iterator si;
3724 if (TEST_BIT (blocks_visited, bb->index))
3727 SET_BIT (blocks_visited, bb->index);
3729 need_assert = false;
3731 /* Traverse all PHI nodes in BB marking used operands. */
3732 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3734 use_operand_p arg_p;
3737 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
3739 tree arg = USE_FROM_PTR (arg_p);
3740 if (TREE_CODE (arg) == SSA_NAME)
3742 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
3743 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
3748 /* Traverse all the statements in BB marking used names and looking
3749 for statements that may infer assertions for their used operands. */
3751 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3756 stmt = bsi_stmt (si);
3758 /* See if we can derive an assertion for any of STMT's operands. */
3759 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
3762 enum tree_code comp_code;
3764 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
3765 the sub-graph of a conditional block, when we return from
3766 this recursive walk, our parent will use the
3767 FOUND_IN_SUBGRAPH bitset to determine if one of the
3768 operands it was looking for was present in the sub-graph. */
3769 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3771 /* If OP is used in such a way that we can infer a value
3772 range for it, and we don't find a previous assertion for
3773 it, create a new assertion location node for OP. */
3774 if (infer_value_range (stmt, op, &comp_code, &value))
3776 /* If we are able to infer a nonzero value range for OP,
3777 then walk backwards through the use-def chain to see if OP
3778 was set via a typecast.
3780 If so, then we can also infer a nonzero value range
3781 for the operand of the NOP_EXPR. */
3782 if (comp_code == NE_EXPR && integer_zerop (value))
3785 tree def_stmt = SSA_NAME_DEF_STMT (t);
3787 while (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3789 (GIMPLE_STMT_OPERAND (def_stmt, 1)) == NOP_EXPR
3791 (TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1),
3794 (TREE_TYPE (TREE_OPERAND
3795 (GIMPLE_STMT_OPERAND (def_stmt,
3798 t = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3799 def_stmt = SSA_NAME_DEF_STMT (t);
3801 /* Note we want to register the assert for the
3802 operand of the NOP_EXPR after SI, not after the
3804 if (! has_single_use (t))
3806 register_new_assert_for (t, comp_code, value,
3813 /* If OP is used only once, namely in this STMT, don't
3814 bother creating an ASSERT_EXPR for it. Such an
3815 ASSERT_EXPR would do nothing but increase compile time. */
3816 if (!has_single_use (op))
3818 register_new_assert_for (op, comp_code, value, bb, NULL, si);
3824 /* Remember the last statement of the block. */
3828 /* If BB's last statement is a conditional expression
3829 involving integer operands, recurse into each of the sub-graphs
3830 rooted at BB to determine if we need to add ASSERT_EXPRs. */
3832 && TREE_CODE (last) == COND_EXPR
3833 && !fp_predicate (COND_EXPR_COND (last))
3834 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
3835 need_assert |= find_conditional_asserts (bb, last);
3837 /* Recurse into the dominator children of BB. */
3838 for (son = first_dom_son (CDI_DOMINATORS, bb);
3840 son = next_dom_son (CDI_DOMINATORS, son))
3841 need_assert |= find_assert_locations (son);
3847 /* Create an ASSERT_EXPR for NAME and insert it in the location
3848 indicated by LOC. Return true if we made any edge insertions. */
3851 process_assert_insertions_for (tree name, assert_locus_t loc)
3853 /* Build the comparison expression NAME_i COMP_CODE VAL. */
3854 tree stmt, cond, assert_expr;
3858 cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
3859 assert_expr = build_assert_expr_for (cond, name);
3863 /* We have been asked to insert the assertion on an edge. This
3864 is used only by COND_EXPR and SWITCH_EXPR assertions. */
3865 #if defined ENABLE_CHECKING
3866 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
3867 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
3870 bsi_insert_on_edge (loc->e, assert_expr);
3874 /* Otherwise, we can insert right after LOC->SI iff the
3875 statement must not be the last statement in the block. */
3876 stmt = bsi_stmt (loc->si);
3877 if (!stmt_ends_bb_p (stmt))
3879 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
3883 /* If STMT must be the last statement in BB, we can only insert new
3884 assertions on the non-abnormal edge out of BB. Note that since
3885 STMT is not control flow, there may only be one non-abnormal edge
3887 FOR_EACH_EDGE (e, ei, loc->bb->succs)
3888 if (!(e->flags & EDGE_ABNORMAL))
3890 bsi_insert_on_edge (e, assert_expr);
3898 /* Process all the insertions registered for every name N_i registered
3899 in NEED_ASSERT_FOR. The list of assertions to be inserted are
3900 found in ASSERTS_FOR[i]. */
3903 process_assert_insertions (void)
3907 bool update_edges_p = false;
3908 int num_asserts = 0;
3910 if (dump_file && (dump_flags & TDF_DETAILS))
3911 dump_all_asserts (dump_file);
3913 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3915 assert_locus_t loc = asserts_for[i];
3920 assert_locus_t next = loc->next;
3921 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
3929 bsi_commit_edge_inserts ();
3931 if (dump_file && (dump_flags & TDF_STATS))
3932 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
3937 /* Traverse the flowgraph looking for conditional jumps to insert range
3938 expressions. These range expressions are meant to provide information
3939 to optimizations that need to reason in terms of value ranges. They
3940 will not be expanded into RTL. For instance, given:
3949 this pass will transform the code into:
3955 x = ASSERT_EXPR <x, x < y>
3960 y = ASSERT_EXPR <y, x <= y>
3964 The idea is that once copy and constant propagation have run, other
3965 optimizations will be able to determine what ranges of values can 'x'
3966 take in different paths of the code, simply by checking the reaching
3967 definition of 'x'. */
3970 insert_range_assertions (void)
3976 found_in_subgraph = sbitmap_alloc (num_ssa_names);
3977 sbitmap_zero (found_in_subgraph);
3979 blocks_visited = sbitmap_alloc (last_basic_block);
3980 sbitmap_zero (blocks_visited);
3982 need_assert_for = BITMAP_ALLOC (NULL);
3983 asserts_for = XCNEWVEC (assert_locus_t, num_ssa_names);
3985 calculate_dominance_info (CDI_DOMINATORS);
3987 update_ssa_p = false;
3988 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
3989 if (find_assert_locations (e->dest))
3990 update_ssa_p = true;
3994 process_assert_insertions ();
3995 update_ssa (TODO_update_ssa_no_phi);
3998 if (dump_file && (dump_flags & TDF_DETAILS))
4000 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
4001 dump_function_to_file (current_function_decl, dump_file, dump_flags);
4004 sbitmap_free (found_in_subgraph);
4006 BITMAP_FREE (need_assert_for);
4009 /* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays
4010 and "struct" hacks. If VRP can determine that the
4011 array subscript is a constant, check if it is outside valid
4012 range. If the array subscript is a RANGE, warn if it is
4013 non-overlapping with valid range.
4014 IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */
4017 check_array_ref (tree ref, location_t* locus, bool ignore_off_by_one)
4019 value_range_t* vr = NULL;
4020 tree low_sub, up_sub;
4021 tree low_bound, up_bound = array_ref_up_bound (ref);
4023 low_sub = up_sub = TREE_OPERAND (ref, 1);
4025 if (!up_bound || !locus || TREE_NO_WARNING (ref)
4026 || TREE_CODE (up_bound) != INTEGER_CST
4027 /* Can not check flexible arrays. */
4028 || (TYPE_SIZE (TREE_TYPE (ref)) == NULL_TREE
4029 && TYPE_DOMAIN (TREE_TYPE (ref)) != NULL_TREE
4030 && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (ref))) == NULL_TREE)
4031 /* Accesses after the end of arrays of size 0 (gcc
4032 extension) and 1 are likely intentional ("struct
4034 || compare_tree_int (up_bound, 1) <= 0)
4037 low_bound = array_ref_low_bound (ref);
4039 if (TREE_CODE (low_sub) == SSA_NAME)
4041 vr = get_value_range (low_sub);
4042 if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
4044 low_sub = vr->type == VR_RANGE ? vr->max : vr->min;
4045 up_sub = vr->type == VR_RANGE ? vr->min : vr->max;
4049 if (vr && vr->type == VR_ANTI_RANGE)
4051 if (TREE_CODE (up_sub) == INTEGER_CST
4052 && tree_int_cst_lt (up_bound, up_sub)
4053 && TREE_CODE (low_sub) == INTEGER_CST
4054 && tree_int_cst_lt (low_sub, low_bound))
4056 warning (OPT_Warray_bounds,
4057 "%Harray subscript is outside array bounds", locus);
4058 TREE_NO_WARNING (ref) = 1;
4061 else if (TREE_CODE (up_sub) == INTEGER_CST
4062 && tree_int_cst_lt (up_bound, up_sub)
4063 && !tree_int_cst_equal (up_bound, up_sub)
4064 && (!ignore_off_by_one
4065 || !tree_int_cst_equal (int_const_binop (PLUS_EXPR,
4071 warning (OPT_Warray_bounds, "%Harray subscript is above array bounds",
4073 TREE_NO_WARNING (ref) = 1;
4075 else if (TREE_CODE (low_sub) == INTEGER_CST
4076 && tree_int_cst_lt (low_sub, low_bound))
4078 warning (OPT_Warray_bounds, "%Harray subscript is below array bounds",
4080 TREE_NO_WARNING (ref) = 1;
4084 /* walk_tree() callback that checks if *TP is
4085 an ARRAY_REF inside an ADDR_EXPR (in which an array
4086 subscript one outside the valid range is allowed). Call
4087 check_array_ref for each ARRAY_REF found. The location is
4091 check_array_bounds (tree *tp, int *walk_subtree, void *data)
4094 tree stmt = (tree)data;
4095 location_t *location = EXPR_LOCUS (stmt);
4097 *walk_subtree = TRUE;
4099 if (TREE_CODE (t) == ARRAY_REF)
4100 check_array_ref (t, location, false /*ignore_off_by_one*/);
4101 else if (TREE_CODE (t) == ADDR_EXPR)
4105 t = TREE_OPERAND (t, 0);
4107 /* Don't warn on statements like
4109 ssa_name = 500 + &array[-200]
4113 ssa_name = &array[-200]
4114 other_name = ssa_name + 300;
4117 produced by other optimizing passes. */
4119 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
4120 && BINARY_CLASS_P (GIMPLE_STMT_OPERAND (stmt, 1)))
4121 *walk_subtree = FALSE;
4123 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
4124 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 0)) == SSA_NAME
4125 && single_imm_use (GIMPLE_STMT_OPERAND (stmt, 0), &op, &use_stmt)
4126 && TREE_CODE (use_stmt) == GIMPLE_MODIFY_STMT
4127 && BINARY_CLASS_P (GIMPLE_STMT_OPERAND (use_stmt, 1)))
4128 *walk_subtree = FALSE;
4130 while (*walk_subtree && handled_component_p (t))
4132 if (TREE_CODE (t) == ARRAY_REF)
4133 check_array_ref (t, location, true /*ignore_off_by_one*/);
4134 t = TREE_OPERAND (t, 0);
4136 *walk_subtree = FALSE;
4142 /* Walk over all statements of all reachable BBs and call check_array_bounds
4146 check_all_array_refs (void)
4149 block_stmt_iterator si;
4153 /* Skip bb's that are clearly unreachable. */
4154 if (single_pred_p (bb))
4156 basic_block pred_bb = EDGE_PRED (bb, 0)->src;
4157 tree ls = NULL_TREE;
4159 if (!bsi_end_p (bsi_last (pred_bb)))
4160 ls = bsi_stmt (bsi_last (pred_bb));
4162 if (ls && TREE_CODE (ls) == COND_EXPR
4163 && ((COND_EXPR_COND (ls) == boolean_false_node
4164 && (EDGE_PRED (bb, 0)->flags & EDGE_TRUE_VALUE))
4165 || (COND_EXPR_COND (ls) == boolean_true_node
4166 && (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE))))
4169 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
4170 walk_tree (bsi_stmt_ptr (si), check_array_bounds,
4171 bsi_stmt (si), NULL);
4175 /* Convert range assertion expressions into the implied copies and
4176 copy propagate away the copies. Doing the trivial copy propagation
4177 here avoids the need to run the full copy propagation pass after
4180 FIXME, this will eventually lead to copy propagation removing the
4181 names that had useful range information attached to them. For
4182 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
4183 then N_i will have the range [3, +INF].
4185 However, by converting the assertion into the implied copy
4186 operation N_i = N_j, we will then copy-propagate N_j into the uses
4187 of N_i and lose the range information. We may want to hold on to
4188 ASSERT_EXPRs a little while longer as the ranges could be used in
4189 things like jump threading.
4191 The problem with keeping ASSERT_EXPRs around is that passes after
4192 VRP need to handle them appropriately.
4194 Another approach would be to make the range information a first
4195 class property of the SSA_NAME so that it can be queried from
4196 any pass. This is made somewhat more complex by the need for
4197 multiple ranges to be associated with one SSA_NAME. */
4200 remove_range_assertions (void)
4203 block_stmt_iterator si;
4205 /* Note that the BSI iterator bump happens at the bottom of the
4206 loop and no bump is necessary if we're removing the statement
4207 referenced by the current BSI. */
4209 for (si = bsi_start (bb); !bsi_end_p (si);)
4211 tree stmt = bsi_stmt (si);
4214 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
4215 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ASSERT_EXPR)
4217 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1), var;
4218 tree cond = fold (ASSERT_EXPR_COND (rhs));
4219 use_operand_p use_p;
4220 imm_use_iterator iter;
4222 gcc_assert (cond != boolean_false_node);
4224 /* Propagate the RHS into every use of the LHS. */
4225 var = ASSERT_EXPR_VAR (rhs);
4226 FOR_EACH_IMM_USE_STMT (use_stmt, iter,
4227 GIMPLE_STMT_OPERAND (stmt, 0))
4228 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
4230 SET_USE (use_p, var);
4231 gcc_assert (TREE_CODE (var) == SSA_NAME);
4234 /* And finally, remove the copy, it is not needed. */
4235 bsi_remove (&si, true);
4236 release_defs (stmt);
4242 sbitmap_free (blocks_visited);
4246 /* Return true if STMT is interesting for VRP. */
4249 stmt_interesting_for_vrp (tree stmt)
4251 if (TREE_CODE (stmt) == PHI_NODE
4252 && is_gimple_reg (PHI_RESULT (stmt))
4253 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
4254 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
4256 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4258 tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
4259 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4261 /* In general, assignments with virtual operands are not useful
4262 for deriving ranges, with the obvious exception of calls to
4263 builtin functions. */
4264 if (TREE_CODE (lhs) == SSA_NAME
4265 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
4266 || POINTER_TYPE_P (TREE_TYPE (lhs)))
4267 && ((TREE_CODE (rhs) == CALL_EXPR
4268 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
4269 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs), 0))
4270 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
4271 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)))
4274 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
4281 /* Initialize local data structures for VRP. */
4284 vrp_initialize (void)
4288 vr_value = XCNEWVEC (value_range_t *, num_ssa_names);
4292 block_stmt_iterator si;
4295 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4297 if (!stmt_interesting_for_vrp (phi))
4299 tree lhs = PHI_RESULT (phi);
4300 set_value_range_to_varying (get_value_range (lhs));
4301 DONT_SIMULATE_AGAIN (phi) = true;
4304 DONT_SIMULATE_AGAIN (phi) = false;
4307 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
4309 tree stmt = bsi_stmt (si);
4311 if (!stmt_interesting_for_vrp (stmt))
4315 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
4316 set_value_range_to_varying (get_value_range (def));
4317 DONT_SIMULATE_AGAIN (stmt) = true;
4321 DONT_SIMULATE_AGAIN (stmt) = false;
4328 /* Visit assignment STMT. If it produces an interesting range, record
4329 the SSA name in *OUTPUT_P. */
4331 static enum ssa_prop_result
4332 vrp_visit_assignment (tree stmt, tree *output_p)
4337 lhs = GIMPLE_STMT_OPERAND (stmt, 0);
4338 rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4340 /* We only keep track of ranges in integral and pointer types. */
4341 if (TREE_CODE (lhs) == SSA_NAME
4342 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
4343 /* It is valid to have NULL MIN/MAX values on a type. See
4344 build_range_type. */
4345 && TYPE_MIN_VALUE (TREE_TYPE (lhs))
4346 && TYPE_MAX_VALUE (TREE_TYPE (lhs)))
4347 || POINTER_TYPE_P (TREE_TYPE (lhs))))
4350 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
4352 extract_range_from_expr (&new_vr, rhs);
4354 /* If STMT is inside a loop, we may be able to know something
4355 else about the range of LHS by examining scalar evolution
4357 if (current_loops && (l = loop_containing_stmt (stmt)))
4358 adjust_range_with_scev (&new_vr, l, stmt, lhs);
4360 if (update_value_range (lhs, &new_vr))
4364 if (dump_file && (dump_flags & TDF_DETAILS))
4366 fprintf (dump_file, "Found new range for ");
4367 print_generic_expr (dump_file, lhs, 0);
4368 fprintf (dump_file, ": ");
4369 dump_value_range (dump_file, &new_vr);
4370 fprintf (dump_file, "\n\n");
4373 if (new_vr.type == VR_VARYING)
4374 return SSA_PROP_VARYING;
4376 return SSA_PROP_INTERESTING;
4379 return SSA_PROP_NOT_INTERESTING;
4382 /* Every other statement produces no useful ranges. */
4383 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
4384 set_value_range_to_varying (get_value_range (def));
4386 return SSA_PROP_VARYING;
4390 /* Compare all the value ranges for names equivalent to VAR with VAL
4391 using comparison code COMP. Return the same value returned by
4392 compare_range_with_value, including the setting of
4393 *STRICT_OVERFLOW_P. */
4396 compare_name_with_value (enum tree_code comp, tree var, tree val,
4397 bool *strict_overflow_p)
4403 int used_strict_overflow;
4405 t = retval = NULL_TREE;
4407 /* Get the set of equivalences for VAR. */
4408 e = get_value_range (var)->equiv;
4410 /* Add VAR to its own set of equivalences so that VAR's value range
4411 is processed by this loop (otherwise, we would have to replicate
4412 the body of the loop just to check VAR's value range). */
4413 bitmap_set_bit (e, SSA_NAME_VERSION (var));
4415 /* Start at -1. Set it to 0 if we do a comparison without relying
4416 on overflow, or 1 if all comparisons rely on overflow. */
4417 used_strict_overflow = -1;
4419 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
4423 value_range_t equiv_vr = *(vr_value[i]);
4425 /* If name N_i does not have a valid range, use N_i as its own
4426 range. This allows us to compare against names that may
4427 have N_i in their ranges. */
4428 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
4430 equiv_vr.type = VR_RANGE;
4431 equiv_vr.min = ssa_name (i);
4432 equiv_vr.max = ssa_name (i);
4436 t = compare_range_with_value (comp, &equiv_vr, val, &sop);
4439 /* If we get different answers from different members
4440 of the equivalence set this check must be in a dead
4441 code region. Folding it to a trap representation
4442 would be correct here. For now just return don't-know. */
4452 used_strict_overflow = 0;
4453 else if (used_strict_overflow < 0)
4454 used_strict_overflow = 1;
4458 /* Remove VAR from its own equivalence set. */
4459 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
4463 if (used_strict_overflow > 0)
4464 *strict_overflow_p = true;
4468 /* We couldn't find a non-NULL value for the predicate. */
4473 /* Given a comparison code COMP and names N1 and N2, compare all the
4474 ranges equivalent to N1 against all the ranges equivalent to N2
4475 to determine the value of N1 COMP N2. Return the same value
4476 returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate
4477 whether we relied on an overflow infinity in the comparison. */
4481 compare_names (enum tree_code comp, tree n1, tree n2,
4482 bool *strict_overflow_p)
4486 bitmap_iterator bi1, bi2;
4488 int used_strict_overflow;
4490 /* Compare the ranges of every name equivalent to N1 against the
4491 ranges of every name equivalent to N2. */
4492 e1 = get_value_range (n1)->equiv;
4493 e2 = get_value_range (n2)->equiv;
4495 /* Add N1 and N2 to their own set of equivalences to avoid
4496 duplicating the body of the loop just to check N1 and N2
4498 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
4499 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
4501 /* If the equivalence sets have a common intersection, then the two
4502 names can be compared without checking their ranges. */
4503 if (bitmap_intersect_p (e1, e2))
4505 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4506 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4508 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
4510 : boolean_false_node;
4513 /* Start at -1. Set it to 0 if we do a comparison without relying
4514 on overflow, or 1 if all comparisons rely on overflow. */
4515 used_strict_overflow = -1;
4517 /* Otherwise, compare all the equivalent ranges. First, add N1 and
4518 N2 to their own set of equivalences to avoid duplicating the body
4519 of the loop just to check N1 and N2 ranges. */
4520 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
4522 value_range_t vr1 = *(vr_value[i1]);
4524 /* If the range is VARYING or UNDEFINED, use the name itself. */
4525 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
4527 vr1.type = VR_RANGE;
4528 vr1.min = ssa_name (i1);
4529 vr1.max = ssa_name (i1);
4532 t = retval = NULL_TREE;
4533 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
4537 value_range_t vr2 = *(vr_value[i2]);
4539 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
4541 vr2.type = VR_RANGE;
4542 vr2.min = ssa_name (i2);
4543 vr2.max = ssa_name (i2);
4546 t = compare_ranges (comp, &vr1, &vr2, &sop);
4549 /* If we get different answers from different members
4550 of the equivalence set this check must be in a dead
4551 code region. Folding it to a trap representation
4552 would be correct here. For now just return don't-know. */
4556 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4557 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4563 used_strict_overflow = 0;
4564 else if (used_strict_overflow < 0)
4565 used_strict_overflow = 1;
4571 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4572 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4573 if (used_strict_overflow > 0)
4574 *strict_overflow_p = true;
4579 /* None of the equivalent ranges are useful in computing this
4581 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4582 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4587 /* Given a conditional predicate COND, try to determine if COND yields
4588 true or false based on the value ranges of its operands. Return
4589 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
4590 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
4591 NULL if the conditional cannot be evaluated at compile time.
4593 If USE_EQUIV_P is true, the ranges of all the names equivalent with
4594 the operands in COND are used when trying to compute its value.
4595 This is only used during final substitution. During propagation,
4596 we only check the range of each variable and not its equivalents.
4598 Set *STRICT_OVERFLOW_P to indicate whether we relied on an overflow
4599 infinity to produce the result. */
4602 vrp_evaluate_conditional_warnv (tree cond, bool use_equiv_p,
4603 bool *strict_overflow_p)
4605 gcc_assert (TREE_CODE (cond) == SSA_NAME
4606 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
4608 if (TREE_CODE (cond) == SSA_NAME)
4614 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node,
4618 value_range_t *vr = get_value_range (cond);
4619 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node,
4623 /* If COND has a known boolean range, return it. */
4627 /* Otherwise, if COND has a symbolic range of exactly one value,
4629 vr = get_value_range (cond);
4630 if (vr->type == VR_RANGE && vr->min == vr->max)
4635 tree op0 = TREE_OPERAND (cond, 0);
4636 tree op1 = TREE_OPERAND (cond, 1);
4638 /* We only deal with integral and pointer types. */
4639 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
4640 && !POINTER_TYPE_P (TREE_TYPE (op0)))
4645 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
4646 return compare_names (TREE_CODE (cond), op0, op1,
4648 else if (TREE_CODE (op0) == SSA_NAME)
4649 return compare_name_with_value (TREE_CODE (cond), op0, op1,
4651 else if (TREE_CODE (op1) == SSA_NAME)
4652 return (compare_name_with_value
4653 (swap_tree_comparison (TREE_CODE (cond)), op1, op0,
4654 strict_overflow_p));
4658 value_range_t *vr0, *vr1;
4660 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
4661 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
4664 return compare_ranges (TREE_CODE (cond), vr0, vr1,
4666 else if (vr0 && vr1 == NULL)
4667 return compare_range_with_value (TREE_CODE (cond), vr0, op1,
4669 else if (vr0 == NULL && vr1)
4670 return (compare_range_with_value
4671 (swap_tree_comparison (TREE_CODE (cond)), vr1, op0,
4672 strict_overflow_p));
4676 /* Anything else cannot be computed statically. */
4680 /* Given COND within STMT, try to simplify it based on value range
4681 information. Return NULL if the conditional can not be evaluated.
4682 The ranges of all the names equivalent with the operands in COND
4683 will be used when trying to compute the value. If the result is
4684 based on undefined signed overflow, issue a warning if
4688 vrp_evaluate_conditional (tree cond, tree stmt)
4694 ret = vrp_evaluate_conditional_warnv (cond, true, &sop);
4698 enum warn_strict_overflow_code wc;
4699 const char* warnmsg;
4701 if (is_gimple_min_invariant (ret))
4703 wc = WARN_STRICT_OVERFLOW_CONDITIONAL;
4704 warnmsg = G_("assuming signed overflow does not occur when "
4705 "simplifying conditional to constant");
4709 wc = WARN_STRICT_OVERFLOW_COMPARISON;
4710 warnmsg = G_("assuming signed overflow does not occur when "
4711 "simplifying conditional");
4714 if (issue_strict_overflow_warning (wc))
4718 if (!EXPR_HAS_LOCATION (stmt))
4719 locus = input_location;
4721 locus = EXPR_LOCATION (stmt);
4722 warning (OPT_Wstrict_overflow, "%H%s", &locus, warnmsg);
4730 /* Visit conditional statement STMT. If we can determine which edge
4731 will be taken out of STMT's basic block, record it in
4732 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
4733 SSA_PROP_VARYING. */
4735 static enum ssa_prop_result
4736 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
4741 *taken_edge_p = NULL;
4743 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
4744 add ASSERT_EXPRs for them. */
4745 if (TREE_CODE (stmt) == SWITCH_EXPR)
4746 return SSA_PROP_VARYING;
4748 cond = COND_EXPR_COND (stmt);
4750 if (dump_file && (dump_flags & TDF_DETAILS))
4755 fprintf (dump_file, "\nVisiting conditional with predicate: ");
4756 print_generic_expr (dump_file, cond, 0);
4757 fprintf (dump_file, "\nWith known ranges\n");
4759 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
4761 fprintf (dump_file, "\t");
4762 print_generic_expr (dump_file, use, 0);
4763 fprintf (dump_file, ": ");
4764 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
4767 fprintf (dump_file, "\n");
4770 /* Compute the value of the predicate COND by checking the known
4771 ranges of each of its operands.
4773 Note that we cannot evaluate all the equivalent ranges here
4774 because those ranges may not yet be final and with the current
4775 propagation strategy, we cannot determine when the value ranges
4776 of the names in the equivalence set have changed.
4778 For instance, given the following code fragment
4782 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
4786 Assume that on the first visit to i_14, i_5 has the temporary
4787 range [8, 8] because the second argument to the PHI function is
4788 not yet executable. We derive the range ~[0, 0] for i_14 and the
4789 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
4790 the first time, since i_14 is equivalent to the range [8, 8], we
4791 determine that the predicate is always false.
4793 On the next round of propagation, i_13 is determined to be
4794 VARYING, which causes i_5 to drop down to VARYING. So, another
4795 visit to i_14 is scheduled. In this second visit, we compute the
4796 exact same range and equivalence set for i_14, namely ~[0, 0] and
4797 { i_5 }. But we did not have the previous range for i_5
4798 registered, so vrp_visit_assignment thinks that the range for
4799 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
4800 is not visited again, which stops propagation from visiting
4801 statements in the THEN clause of that if().
4803 To properly fix this we would need to keep the previous range
4804 value for the names in the equivalence set. This way we would've
4805 discovered that from one visit to the other i_5 changed from
4806 range [8, 8] to VR_VARYING.
4808 However, fixing this apparent limitation may not be worth the
4809 additional checking. Testing on several code bases (GCC, DLV,
4810 MICO, TRAMP3D and SPEC2000) showed that doing this results in
4811 4 more predicates folded in SPEC. */
4813 val = vrp_evaluate_conditional_warnv (cond, false, &sop);
4817 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
4820 if (dump_file && (dump_flags & TDF_DETAILS))
4822 "\nIgnoring predicate evaluation because "
4823 "it assumes that signed overflow is undefined");
4828 if (dump_file && (dump_flags & TDF_DETAILS))
4830 fprintf (dump_file, "\nPredicate evaluates to: ");
4831 if (val == NULL_TREE)
4832 fprintf (dump_file, "DON'T KNOW\n");
4834 print_generic_stmt (dump_file, val, 0);
4837 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
4841 /* Evaluate statement STMT. If the statement produces a useful range,
4842 return SSA_PROP_INTERESTING and record the SSA name with the
4843 interesting range into *OUTPUT_P.
4845 If STMT is a conditional branch and we can determine its truth
4846 value, the taken edge is recorded in *TAKEN_EDGE_P.
4848 If STMT produces a varying value, return SSA_PROP_VARYING. */
4850 static enum ssa_prop_result
4851 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
4857 if (dump_file && (dump_flags & TDF_DETAILS))
4859 fprintf (dump_file, "\nVisiting statement:\n");
4860 print_generic_stmt (dump_file, stmt, dump_flags);
4861 fprintf (dump_file, "\n");
4864 ann = stmt_ann (stmt);
4865 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4867 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4869 /* In general, assignments with virtual operands are not useful
4870 for deriving ranges, with the obvious exception of calls to
4871 builtin functions. */
4872 if ((TREE_CODE (rhs) == CALL_EXPR
4873 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
4874 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs), 0))
4875 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
4876 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
4877 return vrp_visit_assignment (stmt, output_p);
4879 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
4880 return vrp_visit_cond_stmt (stmt, taken_edge_p);
4882 /* All other statements produce nothing of interest for VRP, so mark
4883 their outputs varying and prevent further simulation. */
4884 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
4885 set_value_range_to_varying (get_value_range (def));
4887 return SSA_PROP_VARYING;
4891 /* Meet operation for value ranges. Given two value ranges VR0 and
4892 VR1, store in VR0 a range that contains both VR0 and VR1. This
4893 may not be the smallest possible such range. */
4896 vrp_meet (value_range_t *vr0, value_range_t *vr1)
4898 if (vr0->type == VR_UNDEFINED)
4900 copy_value_range (vr0, vr1);
4904 if (vr1->type == VR_UNDEFINED)
4906 /* Nothing to do. VR0 already has the resulting range. */
4910 if (vr0->type == VR_VARYING)
4912 /* Nothing to do. VR0 already has the resulting range. */
4916 if (vr1->type == VR_VARYING)
4918 set_value_range_to_varying (vr0);
4922 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
4927 /* Compute the convex hull of the ranges. The lower limit of
4928 the new range is the minimum of the two ranges. If they
4929 cannot be compared, then give up. */
4930 cmp = compare_values (vr0->min, vr1->min);
4931 if (cmp == 0 || cmp == 1)
4938 /* Similarly, the upper limit of the new range is the maximum
4939 of the two ranges. If they cannot be compared, then
4941 cmp = compare_values (vr0->max, vr1->max);
4942 if (cmp == 0 || cmp == -1)
4949 /* The resulting set of equivalences is the intersection of
4951 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4952 bitmap_and_into (vr0->equiv, vr1->equiv);
4953 else if (vr0->equiv && !vr1->equiv)
4954 bitmap_clear (vr0->equiv);
4956 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
4958 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
4960 /* Two anti-ranges meet only if their complements intersect.
4961 Only handle the case of identical ranges. */
4962 if (compare_values (vr0->min, vr1->min) == 0
4963 && compare_values (vr0->max, vr1->max) == 0
4964 && compare_values (vr0->min, vr0->max) == 0)
4966 /* The resulting set of equivalences is the intersection of
4968 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4969 bitmap_and_into (vr0->equiv, vr1->equiv);
4970 else if (vr0->equiv && !vr1->equiv)
4971 bitmap_clear (vr0->equiv);
4976 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
4978 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
4979 only handle the case where the ranges have an empty intersection.
4980 The result of the meet operation is the anti-range. */
4981 if (!symbolic_range_p (vr0)
4982 && !symbolic_range_p (vr1)
4983 && !value_ranges_intersect_p (vr0, vr1))
4985 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
4986 set. We need to compute the intersection of the two
4987 equivalence sets. */
4988 if (vr1->type == VR_ANTI_RANGE)
4989 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
4991 /* The resulting set of equivalences is the intersection of
4993 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4994 bitmap_and_into (vr0->equiv, vr1->equiv);
4995 else if (vr0->equiv && !vr1->equiv)
4996 bitmap_clear (vr0->equiv);
5007 /* Failed to find an efficient meet. Before giving up and setting
5008 the result to VARYING, see if we can at least derive a useful
5009 anti-range. FIXME, all this nonsense about distinguishing
5010 anti-ranges from ranges is necessary because of the odd
5011 semantics of range_includes_zero_p and friends. */
5012 if (!symbolic_range_p (vr0)
5013 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
5014 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
5015 && !symbolic_range_p (vr1)
5016 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
5017 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
5019 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
5021 /* Since this meet operation did not result from the meeting of
5022 two equivalent names, VR0 cannot have any equivalences. */
5024 bitmap_clear (vr0->equiv);
5027 set_value_range_to_varying (vr0);
5031 /* Visit all arguments for PHI node PHI that flow through executable
5032 edges. If a valid value range can be derived from all the incoming
5033 value ranges, set a new range for the LHS of PHI. */
5035 static enum ssa_prop_result
5036 vrp_visit_phi_node (tree phi)
5039 tree lhs = PHI_RESULT (phi);
5040 value_range_t *lhs_vr = get_value_range (lhs);
5041 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
5042 bool all_const = true;
5044 copy_value_range (&vr_result, lhs_vr);
5046 if (dump_file && (dump_flags & TDF_DETAILS))
5048 fprintf (dump_file, "\nVisiting PHI node: ");
5049 print_generic_expr (dump_file, phi, dump_flags);
5052 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
5054 edge e = PHI_ARG_EDGE (phi, i);
5056 if (dump_file && (dump_flags & TDF_DETAILS))
5059 "\n Argument #%d (%d -> %d %sexecutable)\n",
5060 i, e->src->index, e->dest->index,
5061 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
5064 if (e->flags & EDGE_EXECUTABLE)
5066 tree arg = PHI_ARG_DEF (phi, i);
5067 value_range_t vr_arg;
5069 if (TREE_CODE (arg) == SSA_NAME)
5071 vr_arg = *(get_value_range (arg));
5076 vr_arg.type = VR_RANGE;
5079 vr_arg.equiv = NULL;
5082 if (dump_file && (dump_flags & TDF_DETAILS))
5084 fprintf (dump_file, "\t");
5085 print_generic_expr (dump_file, arg, dump_flags);
5086 fprintf (dump_file, "\n\tValue: ");
5087 dump_value_range (dump_file, &vr_arg);
5088 fprintf (dump_file, "\n");
5091 vrp_meet (&vr_result, &vr_arg);
5093 if (vr_result.type == VR_VARYING)
5098 if (vr_result.type == VR_VARYING)
5101 /* To prevent infinite iterations in the algorithm, derive ranges
5102 when the new value is slightly bigger or smaller than the
5104 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE
5107 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
5109 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
5110 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
5112 /* If the new minimum is smaller or larger than the previous
5113 one, go all the way to -INF. In the first case, to avoid
5114 iterating millions of times to reach -INF, and in the
5115 other case to avoid infinite bouncing between different
5117 if (cmp_min > 0 || cmp_min < 0)
5119 /* If we will end up with a (-INF, +INF) range, set it
5121 if (is_positive_overflow_infinity (vr_result.max)
5123 == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max))))
5126 if (!needs_overflow_infinity (TREE_TYPE (vr_result.min)))
5127 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
5128 else if (supports_overflow_infinity (TREE_TYPE (vr_result.min)))
5130 negative_overflow_infinity (TREE_TYPE (vr_result.min));
5135 /* Similarly, if the new maximum is smaller or larger than
5136 the previous one, go all the way to +INF. */
5137 if (cmp_max < 0 || cmp_max > 0)
5139 /* If we will end up with a (-INF, +INF) range, set it
5141 if (is_negative_overflow_infinity (vr_result.min)
5143 == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))))
5146 if (!needs_overflow_infinity (TREE_TYPE (vr_result.max)))
5147 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
5148 else if (supports_overflow_infinity (TREE_TYPE (vr_result.max)))
5150 positive_overflow_infinity (TREE_TYPE (vr_result.max));
5157 /* If the new range is different than the previous value, keep
5159 if (update_value_range (lhs, &vr_result))
5160 return SSA_PROP_INTERESTING;
5162 /* Nothing changed, don't add outgoing edges. */
5163 return SSA_PROP_NOT_INTERESTING;
5165 /* No match found. Set the LHS to VARYING. */
5167 set_value_range_to_varying (lhs_vr);
5168 return SSA_PROP_VARYING;
5171 /* Simplify a division or modulo operator to a right shift or
5172 bitwise and if the first operand is unsigned or is greater
5173 than zero and the second operand is an exact power of two. */
5176 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
5179 tree op = TREE_OPERAND (rhs, 0);
5180 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
5182 if (TYPE_UNSIGNED (TREE_TYPE (op)))
5184 val = integer_one_node;
5190 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node, &sop);
5194 && integer_onep (val)
5195 && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
5199 if (!EXPR_HAS_LOCATION (stmt))
5200 locus = input_location;
5202 locus = EXPR_LOCATION (stmt);
5203 warning (OPT_Wstrict_overflow,
5204 ("%Hassuming signed overflow does not occur when "
5205 "simplifying / or %% to >> or &"),
5210 if (val && integer_onep (val))
5213 tree op0 = TREE_OPERAND (rhs, 0);
5214 tree op1 = TREE_OPERAND (rhs, 1);
5216 if (rhs_code == TRUNC_DIV_EXPR)
5218 t = build_int_cst (NULL_TREE, tree_log2 (op1));
5219 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
5223 t = build_int_cst (TREE_TYPE (op1), 1);
5224 t = int_const_binop (MINUS_EXPR, op1, t, 0);
5225 t = fold_convert (TREE_TYPE (op0), t);
5226 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
5229 GIMPLE_STMT_OPERAND (stmt, 1) = t;
5234 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
5235 ABS_EXPR. If the operand is <= 0, then simplify the
5236 ABS_EXPR into a NEGATE_EXPR. */
5239 simplify_abs_using_ranges (tree stmt, tree rhs)
5242 tree op = TREE_OPERAND (rhs, 0);
5243 tree type = TREE_TYPE (op);
5244 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
5246 if (TYPE_UNSIGNED (type))
5248 val = integer_zero_node;
5254 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node, &sop);
5258 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node,
5263 if (integer_zerop (val))
5264 val = integer_one_node;
5265 else if (integer_onep (val))
5266 val = integer_zero_node;
5271 && (integer_onep (val) || integer_zerop (val)))
5275 if (sop && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
5279 if (!EXPR_HAS_LOCATION (stmt))
5280 locus = input_location;
5282 locus = EXPR_LOCATION (stmt);
5283 warning (OPT_Wstrict_overflow,
5284 ("%Hassuming signed overflow does not occur when "
5285 "simplifying abs (X) to X or -X"),
5289 if (integer_onep (val))
5290 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
5294 GIMPLE_STMT_OPERAND (stmt, 1) = t;
5300 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
5301 a known value range VR.
5303 If there is one and only one value which will satisfy the
5304 conditional, then return that value. Else return NULL. */
5307 test_for_singularity (enum tree_code cond_code, tree op0,
5308 tree op1, value_range_t *vr)
5313 /* Extract minimum/maximum values which satisfy the
5314 the conditional as it was written. */
5315 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
5317 /* This should not be negative infinity; there is no overflow
5319 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
5322 if (cond_code == LT_EXPR && !is_overflow_infinity (max))
5324 tree one = build_int_cst (TREE_TYPE (op0), 1);
5325 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
5328 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
5330 /* This should not be positive infinity; there is no overflow
5332 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
5335 if (cond_code == GT_EXPR && !is_overflow_infinity (min))
5337 tree one = build_int_cst (TREE_TYPE (op0), 1);
5338 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
5342 /* Now refine the minimum and maximum values using any
5343 value range information we have for op0. */
5346 if (compare_values (vr->min, min) == -1)
5350 if (compare_values (vr->max, max) == 1)
5355 /* If the new min/max values have converged to a single value,
5356 then there is only one value which can satisfy the condition,
5357 return that value. */
5358 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
5364 /* Simplify a conditional using a relational operator to an equality
5365 test if the range information indicates only one value can satisfy
5366 the original conditional. */
5369 simplify_cond_using_ranges (tree stmt)
5371 tree cond = COND_EXPR_COND (stmt);
5372 tree op0 = TREE_OPERAND (cond, 0);
5373 tree op1 = TREE_OPERAND (cond, 1);
5374 enum tree_code cond_code = TREE_CODE (cond);
5376 if (cond_code != NE_EXPR
5377 && cond_code != EQ_EXPR
5378 && TREE_CODE (op0) == SSA_NAME
5379 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
5380 && is_gimple_min_invariant (op1))
5382 value_range_t *vr = get_value_range (op0);
5384 /* If we have range information for OP0, then we might be
5385 able to simplify this conditional. */
5386 if (vr->type == VR_RANGE)
5388 tree new = test_for_singularity (cond_code, op0, op1, vr);
5394 fprintf (dump_file, "Simplified relational ");
5395 print_generic_expr (dump_file, cond, 0);
5396 fprintf (dump_file, " into ");
5399 COND_EXPR_COND (stmt)
5400 = build2 (EQ_EXPR, boolean_type_node, op0, new);
5405 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
5406 fprintf (dump_file, "\n");
5412 /* Try again after inverting the condition. We only deal
5413 with integral types here, so no need to worry about
5414 issues with inverting FP comparisons. */
5415 cond_code = invert_tree_comparison (cond_code, false);
5416 new = test_for_singularity (cond_code, op0, op1, vr);
5422 fprintf (dump_file, "Simplified relational ");
5423 print_generic_expr (dump_file, cond, 0);
5424 fprintf (dump_file, " into ");
5427 COND_EXPR_COND (stmt)
5428 = build2 (NE_EXPR, boolean_type_node, op0, new);
5433 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
5434 fprintf (dump_file, "\n");
5443 /* Simplify STMT using ranges if possible. */
5446 simplify_stmt_using_ranges (tree stmt)
5448 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
5450 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
5451 enum tree_code rhs_code = TREE_CODE (rhs);
5453 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
5454 and BIT_AND_EXPR respectively if the first operand is greater
5455 than zero and the second operand is an exact power of two. */
5456 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
5457 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
5458 && integer_pow2p (TREE_OPERAND (rhs, 1)))
5459 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
5461 /* Transform ABS (X) into X or -X as appropriate. */
5462 if (rhs_code == ABS_EXPR
5463 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
5464 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
5465 simplify_abs_using_ranges (stmt, rhs);
5467 else if (TREE_CODE (stmt) == COND_EXPR
5468 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
5470 simplify_cond_using_ranges (stmt);
5474 /* Stack of dest,src equivalency pairs that need to be restored after
5475 each attempt to thread a block's incoming edge to an outgoing edge.
5477 A NULL entry is used to mark the end of pairs which need to be
5479 static VEC(tree,heap) *stack;
5481 /* A trivial wrapper so that we can present the generic jump threading
5482 code with a simple API for simplifying statements. STMT is the
5483 statement we want to simplify, WITHIN_STMT provides the location
5484 for any overflow warnings. */
5487 simplify_stmt_for_jump_threading (tree stmt, tree within_stmt)
5489 /* We only use VRP information to simplify conditionals. This is
5490 overly conservative, but it's unclear if doing more would be
5491 worth the compile time cost. */
5492 if (TREE_CODE (stmt) != COND_EXPR)
5495 return vrp_evaluate_conditional (COND_EXPR_COND (stmt), within_stmt);
5498 /* Blocks which have more than one predecessor and more than
5499 one successor present jump threading opportunities. ie,
5500 when the block is reached from a specific predecessor, we
5501 may be able to determine which of the outgoing edges will
5502 be traversed. When this optimization applies, we are able
5503 to avoid conditionals at runtime and we may expose secondary
5504 optimization opportunities.
5506 This routine is effectively a driver for the generic jump
5507 threading code. It basically just presents the generic code
5508 with edges that may be suitable for jump threading.
5510 Unlike DOM, we do not iterate VRP if jump threading was successful.
5511 While iterating may expose new opportunities for VRP, it is expected
5512 those opportunities would be very limited and the compile time cost
5513 to expose those opportunities would be significant.
5515 As jump threading opportunities are discovered, they are registered
5516 for later realization. */
5519 identify_jump_threads (void)
5524 /* Ugh. When substituting values earlier in this pass we can
5525 wipe the dominance information. So rebuild the dominator
5526 information as we need it within the jump threading code. */
5527 calculate_dominance_info (CDI_DOMINATORS);
5529 /* We do not allow VRP information to be used for jump threading
5530 across a back edge in the CFG. Otherwise it becomes too
5531 difficult to avoid eliminating loop exit tests. Of course
5532 EDGE_DFS_BACK is not accurate at this time so we have to
5534 mark_dfs_back_edges ();
5536 /* Allocate our unwinder stack to unwind any temporary equivalences
5537 that might be recorded. */
5538 stack = VEC_alloc (tree, heap, 20);
5540 /* To avoid lots of silly node creation, we create a single
5541 conditional and just modify it in-place when attempting to
5543 dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL);
5544 dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL);
5546 /* Walk through all the blocks finding those which present a
5547 potential jump threading opportunity. We could set this up
5548 as a dominator walker and record data during the walk, but
5549 I doubt it's worth the effort for the classes of jump
5550 threading opportunities we are trying to identify at this
5551 point in compilation. */
5556 /* If the generic jump threading code does not find this block
5557 interesting, then there is nothing to do. */
5558 if (! potentially_threadable_block (bb))
5561 /* We only care about blocks ending in a COND_EXPR. While there
5562 may be some value in handling SWITCH_EXPR here, I doubt it's
5563 terribly important. */
5564 last = bsi_stmt (bsi_last (bb));
5565 if (TREE_CODE (last) != COND_EXPR)
5568 /* We're basically looking for any kind of conditional with
5569 integral type arguments. */
5570 cond = COND_EXPR_COND (last);
5571 if ((TREE_CODE (cond) == SSA_NAME
5572 && INTEGRAL_TYPE_P (TREE_TYPE (cond)))
5573 || (COMPARISON_CLASS_P (cond)
5574 && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
5575 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0)))
5576 && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME
5577 || is_gimple_min_invariant (TREE_OPERAND (cond, 1)))
5578 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
5583 /* We've got a block with multiple predecessors and multiple
5584 successors which also ends in a suitable conditional. For
5585 each predecessor, see if we can thread it to a specific
5587 FOR_EACH_EDGE (e, ei, bb->preds)
5589 /* Do not thread across back edges or abnormal edges
5591 if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
5594 thread_across_edge (dummy, e, true,
5596 simplify_stmt_for_jump_threading);
5601 /* We do not actually update the CFG or SSA graphs at this point as
5602 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
5603 handle ASSERT_EXPRs gracefully. */
5606 /* We identified all the jump threading opportunities earlier, but could
5607 not transform the CFG at that time. This routine transforms the
5608 CFG and arranges for the dominator tree to be rebuilt if necessary.
5610 Note the SSA graph update will occur during the normal TODO
5611 processing by the pass manager. */
5613 finalize_jump_threads (void)
5615 bool cfg_altered = false;
5616 cfg_altered = thread_through_all_blocks ();
5618 /* If we threaded jumps, then we need to recompute the dominance
5621 free_dominance_info (CDI_DOMINATORS);
5622 VEC_free (tree, heap, stack);
5626 /* Traverse all the blocks folding conditionals with known ranges. */
5632 prop_value_t *single_val_range;
5633 bool do_value_subst_p;
5637 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
5638 dump_all_value_ranges (dump_file);
5639 fprintf (dump_file, "\n");
5642 /* We may have ended with ranges that have exactly one value. Those
5643 values can be substituted as any other copy/const propagated
5644 value using substitute_and_fold. */
5645 single_val_range = XCNEWVEC (prop_value_t, num_ssa_names);
5647 do_value_subst_p = false;
5648 for (i = 0; i < num_ssa_names; i++)
5650 && vr_value[i]->type == VR_RANGE
5651 && vr_value[i]->min == vr_value[i]->max)
5653 single_val_range[i].value = vr_value[i]->min;
5654 do_value_subst_p = true;
5657 if (!do_value_subst_p)
5659 /* We found no single-valued ranges, don't waste time trying to
5660 do single value substitution in substitute_and_fold. */
5661 free (single_val_range);
5662 single_val_range = NULL;
5665 substitute_and_fold (single_val_range, true);
5667 if (warn_array_bounds)
5668 check_all_array_refs ();
5670 /* We must identify jump threading opportunities before we release
5671 the datastructures built by VRP. */
5672 identify_jump_threads ();
5674 /* Free allocated memory. */
5675 for (i = 0; i < num_ssa_names; i++)
5678 BITMAP_FREE (vr_value[i]->equiv);
5682 free (single_val_range);
5685 /* So that we can distinguish between VRP data being available
5686 and not available. */
5691 /* Main entry point to VRP (Value Range Propagation). This pass is
5692 loosely based on J. R. C. Patterson, ``Accurate Static Branch
5693 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
5694 Programming Language Design and Implementation, pp. 67-78, 1995.
5695 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
5697 This is essentially an SSA-CCP pass modified to deal with ranges
5698 instead of constants.
5700 While propagating ranges, we may find that two or more SSA name
5701 have equivalent, though distinct ranges. For instance,
5704 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
5706 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
5710 In the code above, pointer p_5 has range [q_2, q_2], but from the
5711 code we can also determine that p_5 cannot be NULL and, if q_2 had
5712 a non-varying range, p_5's range should also be compatible with it.
5714 These equivalences are created by two expressions: ASSERT_EXPR and
5715 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
5716 result of another assertion, then we can use the fact that p_5 and
5717 p_4 are equivalent when evaluating p_5's range.
5719 Together with value ranges, we also propagate these equivalences
5720 between names so that we can take advantage of information from
5721 multiple ranges when doing final replacement. Note that this
5722 equivalency relation is transitive but not symmetric.
5724 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
5725 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
5726 in contexts where that assertion does not hold (e.g., in line 6).
5728 TODO, the main difference between this pass and Patterson's is that
5729 we do not propagate edge probabilities. We only compute whether
5730 edges can be taken or not. That is, instead of having a spectrum
5731 of jump probabilities between 0 and 1, we only deal with 0, 1 and
5732 DON'T KNOW. In the future, it may be worthwhile to propagate
5733 probabilities to aid branch prediction. */
5738 insert_range_assertions ();
5740 loop_optimizer_init (LOOPS_NORMAL);
5745 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
5751 loop_optimizer_finalize ();
5754 /* ASSERT_EXPRs must be removed before finalizing jump threads
5755 as finalizing jump threads calls the CFG cleanup code which
5756 does not properly handle ASSERT_EXPRs. */
5757 remove_range_assertions ();
5759 /* If we exposed any new variables, go ahead and put them into
5760 SSA form now, before we handle jump threading. This simplifies
5761 interactions between rewriting of _DECL nodes into SSA form
5762 and rewriting SSA_NAME nodes into SSA form after block
5763 duplication and CFG manipulation. */
5764 update_ssa (TODO_update_ssa);
5766 finalize_jump_threads ();
5773 return flag_tree_vrp != 0;
5776 struct tree_opt_pass pass_vrp =
5779 gate_vrp, /* gate */
5780 execute_vrp, /* execute */
5783 0, /* static_pass_number */
5784 TV_TREE_VRP, /* tv_id */
5785 PROP_ssa | PROP_alias, /* properties_required */
5786 0, /* properties_provided */
5787 0, /* properties_destroyed */
5788 0, /* todo_flags_start */
5793 | TODO_update_ssa, /* todo_flags_finish */