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 fold_defer_overflow_warnings ();
652 tcmp = fold_binary_to_constant (LT_EXPR, boolean_type_node, val, val2);
654 fold_undefer_and_ignore_overflow_warnings ();
659 if (!integer_zerop (tcmp))
663 /* val >= val2, not considering overflow infinity. */
664 if (is_negative_overflow_infinity (val))
665 return is_negative_overflow_infinity (val2) ? 0 : 1;
666 else if (is_positive_overflow_infinity (val2))
667 return is_positive_overflow_infinity (val) ? 0 : 1;
672 /* Compare two values VAL1 and VAL2. Return
674 -2 if VAL1 and VAL2 cannot be compared at compile-time,
677 +1 if VAL1 > VAL2, and
680 This is similar to tree_int_cst_compare but supports pointer values
681 and values that cannot be compared at compile time.
683 If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to
684 true if the return value is only valid if we assume that signed
685 overflow is undefined. */
688 compare_values_warnv (tree val1, tree val2, bool *strict_overflow_p)
693 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
695 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
696 == POINTER_TYPE_P (TREE_TYPE (val2)));
698 if ((TREE_CODE (val1) == SSA_NAME
699 || TREE_CODE (val1) == PLUS_EXPR
700 || TREE_CODE (val1) == MINUS_EXPR)
701 && (TREE_CODE (val2) == SSA_NAME
702 || TREE_CODE (val2) == PLUS_EXPR
703 || TREE_CODE (val2) == MINUS_EXPR))
706 enum tree_code code1, code2;
708 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
709 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
710 same name, return -2. */
711 if (TREE_CODE (val1) == SSA_NAME)
719 code1 = TREE_CODE (val1);
720 n1 = TREE_OPERAND (val1, 0);
721 c1 = TREE_OPERAND (val1, 1);
722 if (tree_int_cst_sgn (c1) == -1)
724 if (is_negative_overflow_infinity (c1))
726 c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1);
729 code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
733 if (TREE_CODE (val2) == SSA_NAME)
741 code2 = TREE_CODE (val2);
742 n2 = TREE_OPERAND (val2, 0);
743 c2 = TREE_OPERAND (val2, 1);
744 if (tree_int_cst_sgn (c2) == -1)
746 if (is_negative_overflow_infinity (c2))
748 c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2);
751 code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
755 /* Both values must use the same name. */
759 if (code1 == SSA_NAME
760 && code2 == SSA_NAME)
764 /* If overflow is defined we cannot simplify more. */
765 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1)))
768 if (strict_overflow_p != NULL)
769 *strict_overflow_p = true;
771 if (code1 == SSA_NAME)
773 if (code2 == PLUS_EXPR)
774 /* NAME < NAME + CST */
776 else if (code2 == MINUS_EXPR)
777 /* NAME > NAME - CST */
780 else if (code1 == PLUS_EXPR)
782 if (code2 == SSA_NAME)
783 /* NAME + CST > NAME */
785 else if (code2 == PLUS_EXPR)
786 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
787 return compare_values_warnv (c1, c2, strict_overflow_p);
788 else if (code2 == MINUS_EXPR)
789 /* NAME + CST1 > NAME - CST2 */
792 else if (code1 == MINUS_EXPR)
794 if (code2 == SSA_NAME)
795 /* NAME - CST < NAME */
797 else if (code2 == PLUS_EXPR)
798 /* NAME - CST1 < NAME + CST2 */
800 else if (code2 == MINUS_EXPR)
801 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
802 C1 and C2 are swapped in the call to compare_values. */
803 return compare_values_warnv (c2, c1, strict_overflow_p);
809 /* We cannot compare non-constants. */
810 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
813 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
815 /* We cannot compare overflowed values, except for overflow
817 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
819 if (strict_overflow_p != NULL)
820 *strict_overflow_p = true;
821 if (is_negative_overflow_infinity (val1))
822 return is_negative_overflow_infinity (val2) ? 0 : -1;
823 else if (is_negative_overflow_infinity (val2))
825 else if (is_positive_overflow_infinity (val1))
826 return is_positive_overflow_infinity (val2) ? 0 : 1;
827 else if (is_positive_overflow_infinity (val2))
832 return tree_int_cst_compare (val1, val2);
838 /* First see if VAL1 and VAL2 are not the same. */
839 if (val1 == val2 || operand_equal_p (val1, val2, 0))
842 /* If VAL1 is a lower address than VAL2, return -1. */
843 if (operand_less_p (val1, val2) == 1)
846 /* If VAL1 is a higher address than VAL2, return +1. */
847 if (operand_less_p (val2, val1) == 1)
850 /* If VAL1 is different than VAL2, return +2.
851 For integer constants we either have already returned -1 or 1
852 or they are equivalent. We still might succeed in proving
853 something about non-trivial operands. */
854 if (TREE_CODE (val1) != INTEGER_CST
855 || TREE_CODE (val2) != INTEGER_CST)
857 t = fold_binary_to_constant (NE_EXPR, boolean_type_node, val1, val2);
858 if (t && tree_expr_nonzero_p (t))
866 /* Compare values like compare_values_warnv, but treat comparisons of
867 nonconstants which rely on undefined overflow as incomparable. */
870 compare_values (tree val1, tree val2)
876 ret = compare_values_warnv (val1, val2, &sop);
878 && (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2)))
884 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
885 0 if VAL is not inside VR,
886 -2 if we cannot tell either way.
888 FIXME, the current semantics of this functions are a bit quirky
889 when taken in the context of VRP. In here we do not care
890 about VR's type. If VR is the anti-range ~[3, 5] the call
891 value_inside_range (4, VR) will return 1.
893 This is counter-intuitive in a strict sense, but the callers
894 currently expect this. They are calling the function
895 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
896 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
899 This also applies to value_ranges_intersect_p and
900 range_includes_zero_p. The semantics of VR_RANGE and
901 VR_ANTI_RANGE should be encoded here, but that also means
902 adapting the users of these functions to the new semantics.
904 Benchmark compile/20001226-1.c compilation time after changing this
908 value_inside_range (tree val, value_range_t * vr)
912 cmp1 = operand_less_p (val, vr->min);
918 cmp2 = operand_less_p (vr->max, val);
926 /* Return true if value ranges VR0 and VR1 have a non-empty
929 Benchmark compile/20001226-1.c compilation time after changing this
934 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
936 /* The value ranges do not intersect if the maximum of the first range is
937 less than the minimum of the second range or vice versa.
938 When those relations are unknown, we can't do any better. */
939 if (operand_less_p (vr0->max, vr1->min) != 0)
941 if (operand_less_p (vr1->max, vr0->min) != 0)
947 /* Return true if VR includes the value zero, false otherwise. FIXME,
948 currently this will return false for an anti-range like ~[-4, 3].
949 This will be wrong when the semantics of value_inside_range are
950 modified (currently the users of this function expect these
954 range_includes_zero_p (value_range_t *vr)
958 gcc_assert (vr->type != VR_UNDEFINED
959 && vr->type != VR_VARYING
960 && !symbolic_range_p (vr));
962 zero = build_int_cst (TREE_TYPE (vr->min), 0);
963 return (value_inside_range (zero, vr) == 1);
966 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
967 false otherwise or if no value range information is available. */
970 ssa_name_nonnegative_p (tree t)
972 value_range_t *vr = get_value_range (t);
977 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
978 which would return a useful value should be encoded as a VR_RANGE. */
979 if (vr->type == VR_RANGE)
981 int result = compare_values (vr->min, integer_zero_node);
983 return (result == 0 || result == 1);
988 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
989 false otherwise or if no value range information is available. */
992 ssa_name_nonzero_p (tree t)
994 value_range_t *vr = get_value_range (t);
999 /* A VR_RANGE which does not include zero is a nonzero value. */
1000 if (vr->type == VR_RANGE && !symbolic_range_p (vr))
1001 return ! range_includes_zero_p (vr);
1003 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
1004 if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr))
1005 return range_includes_zero_p (vr);
1011 /* Extract value range information from an ASSERT_EXPR EXPR and store
1015 extract_range_from_assert (value_range_t *vr_p, tree expr)
1017 tree var, cond, limit, min, max, type;
1018 value_range_t *var_vr, *limit_vr;
1019 enum tree_code cond_code;
1021 var = ASSERT_EXPR_VAR (expr);
1022 cond = ASSERT_EXPR_COND (expr);
1024 gcc_assert (COMPARISON_CLASS_P (cond));
1026 /* Find VAR in the ASSERT_EXPR conditional. */
1027 if (var == TREE_OPERAND (cond, 0))
1029 /* If the predicate is of the form VAR COMP LIMIT, then we just
1030 take LIMIT from the RHS and use the same comparison code. */
1031 limit = TREE_OPERAND (cond, 1);
1032 cond_code = TREE_CODE (cond);
1036 /* If the predicate is of the form LIMIT COMP VAR, then we need
1037 to flip around the comparison code to create the proper range
1039 limit = TREE_OPERAND (cond, 0);
1040 cond_code = swap_tree_comparison (TREE_CODE (cond));
1043 type = TREE_TYPE (limit);
1044 gcc_assert (limit != var);
1046 /* For pointer arithmetic, we only keep track of pointer equality
1048 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
1050 set_value_range_to_varying (vr_p);
1054 /* If LIMIT is another SSA name and LIMIT has a range of its own,
1055 try to use LIMIT's range to avoid creating symbolic ranges
1057 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
1059 /* LIMIT's range is only interesting if it has any useful information. */
1061 && (limit_vr->type == VR_UNDEFINED
1062 || limit_vr->type == VR_VARYING
1063 || symbolic_range_p (limit_vr)))
1066 /* Initially, the new range has the same set of equivalences of
1067 VAR's range. This will be revised before returning the final
1068 value. Since assertions may be chained via mutually exclusive
1069 predicates, we will need to trim the set of equivalences before
1071 gcc_assert (vr_p->equiv == NULL);
1072 vr_p->equiv = BITMAP_ALLOC (NULL);
1073 add_equivalence (vr_p->equiv, var);
1075 /* Extract a new range based on the asserted comparison for VAR and
1076 LIMIT's value range. Notice that if LIMIT has an anti-range, we
1077 will only use it for equality comparisons (EQ_EXPR). For any
1078 other kind of assertion, we cannot derive a range from LIMIT's
1079 anti-range that can be used to describe the new range. For
1080 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
1081 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
1082 no single range for x_2 that could describe LE_EXPR, so we might
1083 as well build the range [b_4, +INF] for it. */
1084 if (cond_code == EQ_EXPR)
1086 enum value_range_type range_type;
1090 range_type = limit_vr->type;
1091 min = limit_vr->min;
1092 max = limit_vr->max;
1096 range_type = VR_RANGE;
1101 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
1103 /* When asserting the equality VAR == LIMIT and LIMIT is another
1104 SSA name, the new range will also inherit the equivalence set
1106 if (TREE_CODE (limit) == SSA_NAME)
1107 add_equivalence (vr_p->equiv, limit);
1109 else if (cond_code == NE_EXPR)
1111 /* As described above, when LIMIT's range is an anti-range and
1112 this assertion is an inequality (NE_EXPR), then we cannot
1113 derive anything from the anti-range. For instance, if
1114 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
1115 not imply that VAR's range is [0, 0]. So, in the case of
1116 anti-ranges, we just assert the inequality using LIMIT and
1119 If LIMIT_VR is a range, we can only use it to build a new
1120 anti-range if LIMIT_VR is a single-valued range. For
1121 instance, if LIMIT_VR is [0, 1], the predicate
1122 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
1123 Rather, it means that for value 0 VAR should be ~[0, 0]
1124 and for value 1, VAR should be ~[1, 1]. We cannot
1125 represent these ranges.
1127 The only situation in which we can build a valid
1128 anti-range is when LIMIT_VR is a single-valued range
1129 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
1130 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
1132 && limit_vr->type == VR_RANGE
1133 && compare_values (limit_vr->min, limit_vr->max) == 0)
1135 min = limit_vr->min;
1136 max = limit_vr->max;
1140 /* In any other case, we cannot use LIMIT's range to build a
1141 valid anti-range. */
1145 /* If MIN and MAX cover the whole range for their type, then
1146 just use the original LIMIT. */
1147 if (INTEGRAL_TYPE_P (type)
1148 && (min == TYPE_MIN_VALUE (type)
1149 || is_negative_overflow_infinity (min))
1150 && (max == TYPE_MAX_VALUE (type)
1151 || is_positive_overflow_infinity (max)))
1154 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
1156 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
1158 min = TYPE_MIN_VALUE (type);
1160 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
1164 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1165 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
1167 max = limit_vr->max;
1170 /* If the maximum value forces us to be out of bounds, simply punt.
1171 It would be pointless to try and do anything more since this
1172 all should be optimized away above us. */
1173 if ((cond_code == LT_EXPR
1174 && compare_values (max, min) == 0)
1175 || is_overflow_infinity (max))
1176 set_value_range_to_varying (vr_p);
1179 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
1180 if (cond_code == LT_EXPR)
1182 tree one = build_int_cst (type, 1);
1183 max = fold_build2 (MINUS_EXPR, type, max, one);
1186 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1189 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
1191 max = TYPE_MAX_VALUE (type);
1193 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
1197 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1198 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
1200 min = limit_vr->min;
1203 /* If the minimum value forces us to be out of bounds, simply punt.
1204 It would be pointless to try and do anything more since this
1205 all should be optimized away above us. */
1206 if ((cond_code == GT_EXPR
1207 && compare_values (min, max) == 0)
1208 || is_overflow_infinity (min))
1209 set_value_range_to_varying (vr_p);
1212 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
1213 if (cond_code == GT_EXPR)
1215 tree one = build_int_cst (type, 1);
1216 min = fold_build2 (PLUS_EXPR, type, min, one);
1219 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1225 /* If VAR already had a known range, it may happen that the new
1226 range we have computed and VAR's range are not compatible. For
1230 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
1232 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
1234 While the above comes from a faulty program, it will cause an ICE
1235 later because p_8 and p_6 will have incompatible ranges and at
1236 the same time will be considered equivalent. A similar situation
1240 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
1242 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
1244 Again i_6 and i_7 will have incompatible ranges. It would be
1245 pointless to try and do anything with i_7's range because
1246 anything dominated by 'if (i_5 < 5)' will be optimized away.
1247 Note, due to the wa in which simulation proceeds, the statement
1248 i_7 = ASSERT_EXPR <...> we would never be visited because the
1249 conditional 'if (i_5 < 5)' always evaluates to false. However,
1250 this extra check does not hurt and may protect against future
1251 changes to VRP that may get into a situation similar to the
1252 NULL pointer dereference example.
1254 Note that these compatibility tests are only needed when dealing
1255 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1256 are both anti-ranges, they will always be compatible, because two
1257 anti-ranges will always have a non-empty intersection. */
1259 var_vr = get_value_range (var);
1261 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1262 ranges or anti-ranges. */
1263 if (vr_p->type == VR_VARYING
1264 || vr_p->type == VR_UNDEFINED
1265 || var_vr->type == VR_VARYING
1266 || var_vr->type == VR_UNDEFINED
1267 || symbolic_range_p (vr_p)
1268 || symbolic_range_p (var_vr))
1271 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
1273 /* If the two ranges have a non-empty intersection, we can
1274 refine the resulting range. Since the assert expression
1275 creates an equivalency and at the same time it asserts a
1276 predicate, we can take the intersection of the two ranges to
1277 get better precision. */
1278 if (value_ranges_intersect_p (var_vr, vr_p))
1280 /* Use the larger of the two minimums. */
1281 if (compare_values (vr_p->min, var_vr->min) == -1)
1286 /* Use the smaller of the two maximums. */
1287 if (compare_values (vr_p->max, var_vr->max) == 1)
1292 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
1296 /* The two ranges do not intersect, set the new range to
1297 VARYING, because we will not be able to do anything
1298 meaningful with it. */
1299 set_value_range_to_varying (vr_p);
1302 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
1303 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
1305 /* A range and an anti-range will cancel each other only if
1306 their ends are the same. For instance, in the example above,
1307 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1308 so VR_P should be set to VR_VARYING. */
1309 if (compare_values (var_vr->min, vr_p->min) == 0
1310 && compare_values (var_vr->max, vr_p->max) == 0)
1311 set_value_range_to_varying (vr_p);
1314 tree min, max, anti_min, anti_max, real_min, real_max;
1317 /* We want to compute the logical AND of the two ranges;
1318 there are three cases to consider.
1321 1. The VR_ANTI_RANGE range is completely within the
1322 VR_RANGE and the endpoints of the ranges are
1323 different. In that case the resulting range
1324 should be whichever range is more precise.
1325 Typically that will be the VR_RANGE.
1327 2. The VR_ANTI_RANGE is completely disjoint from
1328 the VR_RANGE. In this case the resulting range
1329 should be the VR_RANGE.
1331 3. There is some overlap between the VR_ANTI_RANGE
1334 3a. If the high limit of the VR_ANTI_RANGE resides
1335 within the VR_RANGE, then the result is a new
1336 VR_RANGE starting at the high limit of the
1337 the VR_ANTI_RANGE + 1 and extending to the
1338 high limit of the original VR_RANGE.
1340 3b. If the low limit of the VR_ANTI_RANGE resides
1341 within the VR_RANGE, then the result is a new
1342 VR_RANGE starting at the low limit of the original
1343 VR_RANGE and extending to the low limit of the
1344 VR_ANTI_RANGE - 1. */
1345 if (vr_p->type == VR_ANTI_RANGE)
1347 anti_min = vr_p->min;
1348 anti_max = vr_p->max;
1349 real_min = var_vr->min;
1350 real_max = var_vr->max;
1354 anti_min = var_vr->min;
1355 anti_max = var_vr->max;
1356 real_min = vr_p->min;
1357 real_max = vr_p->max;
1361 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1362 not including any endpoints. */
1363 if (compare_values (anti_max, real_max) == -1
1364 && compare_values (anti_min, real_min) == 1)
1366 set_value_range (vr_p, VR_RANGE, real_min,
1367 real_max, vr_p->equiv);
1369 /* Case 2, VR_ANTI_RANGE completely disjoint from
1371 else if (compare_values (anti_min, real_max) == 1
1372 || compare_values (anti_max, real_min) == -1)
1374 set_value_range (vr_p, VR_RANGE, real_min,
1375 real_max, vr_p->equiv);
1377 /* Case 3a, the anti-range extends into the low
1378 part of the real range. Thus creating a new
1379 low for the real range. */
1380 else if (((cmp = compare_values (anti_max, real_min)) == 1
1382 && compare_values (anti_max, real_max) == -1)
1384 gcc_assert (!is_positive_overflow_infinity (anti_max));
1385 if (needs_overflow_infinity (TREE_TYPE (anti_max))
1386 && anti_max == TYPE_MAX_VALUE (TREE_TYPE (anti_max)))
1388 if (!supports_overflow_infinity (TREE_TYPE (var_vr->min)))
1390 set_value_range_to_varying (vr_p);
1393 min = positive_overflow_infinity (TREE_TYPE (var_vr->min));
1396 min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min),
1398 build_int_cst (TREE_TYPE (var_vr->min), 1));
1400 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1402 /* Case 3b, the anti-range extends into the high
1403 part of the real range. Thus creating a new
1404 higher for the real range. */
1405 else if (compare_values (anti_min, real_min) == 1
1406 && ((cmp = compare_values (anti_min, real_max)) == -1
1409 gcc_assert (!is_negative_overflow_infinity (anti_min));
1410 if (needs_overflow_infinity (TREE_TYPE (anti_min))
1411 && anti_min == TYPE_MIN_VALUE (TREE_TYPE (anti_min)))
1413 if (!supports_overflow_infinity (TREE_TYPE (var_vr->min)))
1415 set_value_range_to_varying (vr_p);
1418 max = negative_overflow_infinity (TREE_TYPE (var_vr->min));
1421 max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min),
1423 build_int_cst (TREE_TYPE (var_vr->min), 1));
1425 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1432 /* Extract range information from SSA name VAR and store it in VR. If
1433 VAR has an interesting range, use it. Otherwise, create the
1434 range [VAR, VAR] and return it. This is useful in situations where
1435 we may have conditionals testing values of VARYING names. For
1442 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1446 extract_range_from_ssa_name (value_range_t *vr, tree var)
1448 value_range_t *var_vr = get_value_range (var);
1450 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
1451 copy_value_range (vr, var_vr);
1453 set_value_range (vr, VR_RANGE, var, var, NULL);
1455 add_equivalence (vr->equiv, var);
1459 /* Wrapper around int_const_binop. If the operation overflows and we
1460 are not using wrapping arithmetic, then adjust the result to be
1461 -INF or +INF depending on CODE, VAL1 and VAL2. This can return
1462 NULL_TREE if we need to use an overflow infinity representation but
1463 the type does not support it. */
1466 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
1470 res = int_const_binop (code, val1, val2, 0);
1472 /* If we are not using wrapping arithmetic, operate symbolically
1473 on -INF and +INF. */
1474 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1)))
1476 int checkz = compare_values (res, val1);
1477 bool overflow = false;
1479 /* Ensure that res = val1 [+*] val2 >= val1
1480 or that res = val1 - val2 <= val1. */
1481 if ((code == PLUS_EXPR
1482 && !(checkz == 1 || checkz == 0))
1483 || (code == MINUS_EXPR
1484 && !(checkz == 0 || checkz == -1)))
1488 /* Checking for multiplication overflow is done by dividing the
1489 output of the multiplication by the first input of the
1490 multiplication. If the result of that division operation is
1491 not equal to the second input of the multiplication, then the
1492 multiplication overflowed. */
1493 else if (code == MULT_EXPR && !integer_zerop (val1))
1495 tree tmp = int_const_binop (TRUNC_DIV_EXPR,
1498 int check = compare_values (tmp, val2);
1506 res = copy_node (res);
1507 TREE_OVERFLOW (res) = 1;
1511 else if ((TREE_OVERFLOW (res)
1512 && !TREE_OVERFLOW (val1)
1513 && !TREE_OVERFLOW (val2))
1514 || is_overflow_infinity (val1)
1515 || is_overflow_infinity (val2))
1517 /* If the operation overflowed but neither VAL1 nor VAL2 are
1518 overflown, return -INF or +INF depending on the operation
1519 and the combination of signs of the operands. */
1520 int sgn1 = tree_int_cst_sgn (val1);
1521 int sgn2 = tree_int_cst_sgn (val2);
1523 if (needs_overflow_infinity (TREE_TYPE (res))
1524 && !supports_overflow_infinity (TREE_TYPE (res)))
1527 /* We have to punt on adding infinities of different signs,
1528 since we can't tell what the sign of the result should be.
1529 Likewise for subtracting infinities of the same sign. */
1530 if (((code == PLUS_EXPR && sgn1 != sgn2)
1531 || (code == MINUS_EXPR && sgn1 == sgn2))
1532 && is_overflow_infinity (val1)
1533 && is_overflow_infinity (val2))
1536 /* Don't try to handle division or shifting of infinities. */
1537 if ((code == TRUNC_DIV_EXPR
1538 || code == FLOOR_DIV_EXPR
1539 || code == CEIL_DIV_EXPR
1540 || code == EXACT_DIV_EXPR
1541 || code == ROUND_DIV_EXPR
1542 || code == RSHIFT_EXPR)
1543 && (is_overflow_infinity (val1)
1544 || is_overflow_infinity (val2)))
1547 /* Notice that we only need to handle the restricted set of
1548 operations handled by extract_range_from_binary_expr.
1549 Among them, only multiplication, addition and subtraction
1550 can yield overflow without overflown operands because we
1551 are working with integral types only... except in the
1552 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1553 for division too. */
1555 /* For multiplication, the sign of the overflow is given
1556 by the comparison of the signs of the operands. */
1557 if ((code == MULT_EXPR && sgn1 == sgn2)
1558 /* For addition, the operands must be of the same sign
1559 to yield an overflow. Its sign is therefore that
1560 of one of the operands, for example the first. For
1561 infinite operands X + -INF is negative, not positive. */
1562 || (code == PLUS_EXPR
1564 ? !is_negative_overflow_infinity (val2)
1565 : is_positive_overflow_infinity (val2)))
1566 /* For subtraction, non-infinite operands must be of
1567 different signs to yield an overflow. Its sign is
1568 therefore that of the first operand or the opposite of
1569 that of the second operand. A first operand of 0 counts
1570 as positive here, for the corner case 0 - (-INF), which
1571 overflows, but must yield +INF. For infinite operands 0
1572 - INF is negative, not positive. */
1573 || (code == MINUS_EXPR
1575 ? !is_positive_overflow_infinity (val2)
1576 : is_negative_overflow_infinity (val2)))
1577 /* We only get in here with positive shift count, so the
1578 overflow direction is the same as the sign of val1.
1579 Actually rshift does not overflow at all, but we only
1580 handle the case of shifting overflowed -INF and +INF. */
1581 || (code == RSHIFT_EXPR
1583 /* For division, the only case is -INF / -1 = +INF. */
1584 || code == TRUNC_DIV_EXPR
1585 || code == FLOOR_DIV_EXPR
1586 || code == CEIL_DIV_EXPR
1587 || code == EXACT_DIV_EXPR
1588 || code == ROUND_DIV_EXPR)
1589 return (needs_overflow_infinity (TREE_TYPE (res))
1590 ? positive_overflow_infinity (TREE_TYPE (res))
1591 : TYPE_MAX_VALUE (TREE_TYPE (res)));
1593 return (needs_overflow_infinity (TREE_TYPE (res))
1594 ? negative_overflow_infinity (TREE_TYPE (res))
1595 : TYPE_MIN_VALUE (TREE_TYPE (res)));
1602 /* Extract range information from a binary expression EXPR based on
1603 the ranges of each of its operands and the expression code. */
1606 extract_range_from_binary_expr (value_range_t *vr, tree expr)
1608 enum tree_code code = TREE_CODE (expr);
1609 enum value_range_type type;
1610 tree op0, op1, min, max;
1612 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1613 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1615 /* Not all binary expressions can be applied to ranges in a
1616 meaningful way. Handle only arithmetic operations. */
1617 if (code != PLUS_EXPR
1618 && code != MINUS_EXPR
1619 && code != MULT_EXPR
1620 && code != TRUNC_DIV_EXPR
1621 && code != FLOOR_DIV_EXPR
1622 && code != CEIL_DIV_EXPR
1623 && code != EXACT_DIV_EXPR
1624 && code != ROUND_DIV_EXPR
1625 && code != RSHIFT_EXPR
1628 && code != BIT_AND_EXPR
1629 && code != TRUTH_ANDIF_EXPR
1630 && code != TRUTH_ORIF_EXPR
1631 && code != TRUTH_AND_EXPR
1632 && code != TRUTH_OR_EXPR)
1634 set_value_range_to_varying (vr);
1638 /* Get value ranges for each operand. For constant operands, create
1639 a new value range with the operand to simplify processing. */
1640 op0 = TREE_OPERAND (expr, 0);
1641 if (TREE_CODE (op0) == SSA_NAME)
1642 vr0 = *(get_value_range (op0));
1643 else if (is_gimple_min_invariant (op0))
1644 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1646 set_value_range_to_varying (&vr0);
1648 op1 = TREE_OPERAND (expr, 1);
1649 if (TREE_CODE (op1) == SSA_NAME)
1650 vr1 = *(get_value_range (op1));
1651 else if (is_gimple_min_invariant (op1))
1652 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1654 set_value_range_to_varying (&vr1);
1656 /* If either range is UNDEFINED, so is the result. */
1657 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1659 set_value_range_to_undefined (vr);
1663 /* The type of the resulting value range defaults to VR0.TYPE. */
1666 /* Refuse to operate on VARYING ranges, ranges of different kinds
1667 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1668 because we may be able to derive a useful range even if one of
1669 the operands is VR_VARYING or symbolic range. TODO, we may be
1670 able to derive anti-ranges in some cases. */
1671 if (code != BIT_AND_EXPR
1672 && code != TRUTH_AND_EXPR
1673 && code != TRUTH_OR_EXPR
1674 && (vr0.type == VR_VARYING
1675 || vr1.type == VR_VARYING
1676 || vr0.type != vr1.type
1677 || symbolic_range_p (&vr0)
1678 || symbolic_range_p (&vr1)))
1680 set_value_range_to_varying (vr);
1684 /* Now evaluate the expression to determine the new range. */
1685 if (POINTER_TYPE_P (TREE_TYPE (expr))
1686 || POINTER_TYPE_P (TREE_TYPE (op0))
1687 || POINTER_TYPE_P (TREE_TYPE (op1)))
1689 /* For pointer types, we are really only interested in asserting
1690 whether the expression evaluates to non-NULL. FIXME, we used
1691 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1692 ivopts is generating expressions with pointer multiplication
1694 if (code == PLUS_EXPR)
1696 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1697 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1698 else if (range_is_null (&vr0) && range_is_null (&vr1))
1699 set_value_range_to_null (vr, TREE_TYPE (expr));
1701 set_value_range_to_varying (vr);
1705 /* Subtracting from a pointer, may yield 0, so just drop the
1706 resulting range to varying. */
1707 set_value_range_to_varying (vr);
1713 /* For integer ranges, apply the operation to each end of the
1714 range and see what we end up with. */
1715 if (code == TRUTH_ANDIF_EXPR
1716 || code == TRUTH_ORIF_EXPR
1717 || code == TRUTH_AND_EXPR
1718 || code == TRUTH_OR_EXPR)
1720 /* If one of the operands is zero, we know that the whole
1721 expression evaluates zero. */
1722 if (code == TRUTH_AND_EXPR
1723 && ((vr0.type == VR_RANGE
1724 && integer_zerop (vr0.min)
1725 && integer_zerop (vr0.max))
1726 || (vr1.type == VR_RANGE
1727 && integer_zerop (vr1.min)
1728 && integer_zerop (vr1.max))))
1731 min = max = build_int_cst (TREE_TYPE (expr), 0);
1733 /* If one of the operands is one, we know that the whole
1734 expression evaluates one. */
1735 else if (code == TRUTH_OR_EXPR
1736 && ((vr0.type == VR_RANGE
1737 && integer_onep (vr0.min)
1738 && integer_onep (vr0.max))
1739 || (vr1.type == VR_RANGE
1740 && integer_onep (vr1.min)
1741 && integer_onep (vr1.max))))
1744 min = max = build_int_cst (TREE_TYPE (expr), 1);
1746 else if (vr0.type != VR_VARYING
1747 && vr1.type != VR_VARYING
1748 && vr0.type == vr1.type
1749 && !symbolic_range_p (&vr0)
1750 && !overflow_infinity_range_p (&vr0)
1751 && !symbolic_range_p (&vr1)
1752 && !overflow_infinity_range_p (&vr1))
1754 /* Boolean expressions cannot be folded with int_const_binop. */
1755 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1756 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1760 /* The result of a TRUTH_*_EXPR is always true or false. */
1761 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
1765 else if (code == PLUS_EXPR
1767 || code == MAX_EXPR)
1769 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1770 VR_VARYING. It would take more effort to compute a precise
1771 range for such a case. For example, if we have op0 == 1 and
1772 op1 == -1 with their ranges both being ~[0,0], we would have
1773 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1774 Note that we are guaranteed to have vr0.type == vr1.type at
1776 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1778 set_value_range_to_varying (vr);
1782 /* For operations that make the resulting range directly
1783 proportional to the original ranges, apply the operation to
1784 the same end of each range. */
1785 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1786 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1788 else if (code == MULT_EXPR
1789 || code == TRUNC_DIV_EXPR
1790 || code == FLOOR_DIV_EXPR
1791 || code == CEIL_DIV_EXPR
1792 || code == EXACT_DIV_EXPR
1793 || code == ROUND_DIV_EXPR
1794 || code == RSHIFT_EXPR)
1800 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1801 drop to VR_VARYING. It would take more effort to compute a
1802 precise range for such a case. For example, if we have
1803 op0 == 65536 and op1 == 65536 with their ranges both being
1804 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1805 we cannot claim that the product is in ~[0,0]. Note that we
1806 are guaranteed to have vr0.type == vr1.type at this
1808 if (code == MULT_EXPR
1809 && vr0.type == VR_ANTI_RANGE
1810 && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0)))
1812 set_value_range_to_varying (vr);
1816 /* If we have a RSHIFT_EXPR with any shift values outside [0..prec-1],
1817 then drop to VR_VARYING. Outside of this range we get undefined
1818 behaviour from the shift operation. We cannot even trust
1819 SHIFT_COUNT_TRUNCATED at this stage, because that applies to rtl
1820 shifts, and the operation at the tree level may be widened. */
1821 if (code == RSHIFT_EXPR)
1823 if (vr1.type == VR_ANTI_RANGE
1824 || !vrp_expr_computes_nonnegative (op1, &sop)
1826 (build_int_cst (TREE_TYPE (vr1.max),
1827 TYPE_PRECISION (TREE_TYPE (expr)) - 1),
1830 set_value_range_to_varying (vr);
1835 /* Multiplications and divisions are a bit tricky to handle,
1836 depending on the mix of signs we have in the two ranges, we
1837 need to operate on different values to get the minimum and
1838 maximum values for the new range. One approach is to figure
1839 out all the variations of range combinations and do the
1842 However, this involves several calls to compare_values and it
1843 is pretty convoluted. It's simpler to do the 4 operations
1844 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1845 MAX1) and then figure the smallest and largest values to form
1848 /* Divisions by zero result in a VARYING value. */
1849 else if (code != MULT_EXPR
1850 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1852 set_value_range_to_varying (vr);
1856 /* Compute the 4 cross operations. */
1858 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1859 if (val[0] == NULL_TREE)
1862 if (vr1.max == vr1.min)
1866 val[1] = vrp_int_const_binop (code, vr0.min, vr1.max);
1867 if (val[1] == NULL_TREE)
1871 if (vr0.max == vr0.min)
1875 val[2] = vrp_int_const_binop (code, vr0.max, vr1.min);
1876 if (val[2] == NULL_TREE)
1880 if (vr0.min == vr0.max || vr1.min == vr1.max)
1884 val[3] = vrp_int_const_binop (code, vr0.max, vr1.max);
1885 if (val[3] == NULL_TREE)
1891 set_value_range_to_varying (vr);
1895 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1899 for (i = 1; i < 4; i++)
1901 if (!is_gimple_min_invariant (min)
1902 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
1903 || !is_gimple_min_invariant (max)
1904 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
1909 if (!is_gimple_min_invariant (val[i])
1910 || (TREE_OVERFLOW (val[i])
1911 && !is_overflow_infinity (val[i])))
1913 /* If we found an overflowed value, set MIN and MAX
1914 to it so that we set the resulting range to
1920 if (compare_values (val[i], min) == -1)
1923 if (compare_values (val[i], max) == 1)
1928 else if (code == MINUS_EXPR)
1930 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1931 VR_VARYING. It would take more effort to compute a precise
1932 range for such a case. For example, if we have op0 == 1 and
1933 op1 == 1 with their ranges both being ~[0,0], we would have
1934 op0 - op1 == 0, so we cannot claim that the difference is in
1935 ~[0,0]. Note that we are guaranteed to have
1936 vr0.type == vr1.type at this point. */
1937 if (vr0.type == VR_ANTI_RANGE)
1939 set_value_range_to_varying (vr);
1943 /* For MINUS_EXPR, apply the operation to the opposite ends of
1945 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1946 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1948 else if (code == BIT_AND_EXPR)
1950 if (vr0.type == VR_RANGE
1951 && vr0.min == vr0.max
1952 && TREE_CODE (vr0.max) == INTEGER_CST
1953 && !TREE_OVERFLOW (vr0.max)
1954 && tree_int_cst_sgn (vr0.max) >= 0)
1956 min = build_int_cst (TREE_TYPE (expr), 0);
1959 else if (vr1.type == VR_RANGE
1960 && vr1.min == vr1.max
1961 && TREE_CODE (vr1.max) == INTEGER_CST
1962 && !TREE_OVERFLOW (vr1.max)
1963 && tree_int_cst_sgn (vr1.max) >= 0)
1966 min = build_int_cst (TREE_TYPE (expr), 0);
1971 set_value_range_to_varying (vr);
1978 /* If either MIN or MAX overflowed, then set the resulting range to
1979 VARYING. But we do accept an overflow infinity
1981 if (min == NULL_TREE
1982 || !is_gimple_min_invariant (min)
1983 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
1985 || !is_gimple_min_invariant (max)
1986 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
1988 set_value_range_to_varying (vr);
1994 2) [-INF, +-INF(OVF)]
1995 3) [+-INF(OVF), +INF]
1996 4) [+-INF(OVF), +-INF(OVF)]
1997 We learn nothing when we have INF and INF(OVF) on both sides.
1998 Note that we do accept [-INF, -INF] and [+INF, +INF] without
2000 if ((min == TYPE_MIN_VALUE (TREE_TYPE (min))
2001 || is_overflow_infinity (min))
2002 && (max == TYPE_MAX_VALUE (TREE_TYPE (max))
2003 || is_overflow_infinity (max)))
2005 set_value_range_to_varying (vr);
2009 cmp = compare_values (min, max);
2010 if (cmp == -2 || cmp == 1)
2012 /* If the new range has its limits swapped around (MIN > MAX),
2013 then the operation caused one of them to wrap around, mark
2014 the new range VARYING. */
2015 set_value_range_to_varying (vr);
2018 set_value_range (vr, type, min, max, NULL);
2022 /* Extract range information from a unary expression EXPR based on
2023 the range of its operand and the expression code. */
2026 extract_range_from_unary_expr (value_range_t *vr, tree expr)
2028 enum tree_code code = TREE_CODE (expr);
2031 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2033 /* Refuse to operate on certain unary expressions for which we
2034 cannot easily determine a resulting range. */
2035 if (code == FIX_TRUNC_EXPR
2036 || code == FLOAT_EXPR
2037 || code == BIT_NOT_EXPR
2038 || code == NON_LVALUE_EXPR
2039 || code == CONJ_EXPR)
2041 set_value_range_to_varying (vr);
2045 /* Get value ranges for the operand. For constant operands, create
2046 a new value range with the operand to simplify processing. */
2047 op0 = TREE_OPERAND (expr, 0);
2048 if (TREE_CODE (op0) == SSA_NAME)
2049 vr0 = *(get_value_range (op0));
2050 else if (is_gimple_min_invariant (op0))
2051 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
2053 set_value_range_to_varying (&vr0);
2055 /* If VR0 is UNDEFINED, so is the result. */
2056 if (vr0.type == VR_UNDEFINED)
2058 set_value_range_to_undefined (vr);
2062 /* Refuse to operate on symbolic ranges, or if neither operand is
2063 a pointer or integral type. */
2064 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0))
2065 && !POINTER_TYPE_P (TREE_TYPE (op0)))
2066 || (vr0.type != VR_VARYING
2067 && symbolic_range_p (&vr0)))
2069 set_value_range_to_varying (vr);
2073 /* If the expression involves pointers, we are only interested in
2074 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
2075 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
2080 if (range_is_nonnull (&vr0)
2081 || (tree_expr_nonzero_warnv_p (expr, &sop)
2083 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
2084 else if (range_is_null (&vr0))
2085 set_value_range_to_null (vr, TREE_TYPE (expr));
2087 set_value_range_to_varying (vr);
2092 /* Handle unary expressions on integer ranges. */
2093 if (code == NOP_EXPR || code == CONVERT_EXPR)
2095 tree inner_type = TREE_TYPE (op0);
2096 tree outer_type = TREE_TYPE (expr);
2098 /* If VR0 represents a simple range, then try to convert
2099 the min and max values for the range to the same type
2100 as OUTER_TYPE. If the results compare equal to VR0's
2101 min and max values and the new min is still less than
2102 or equal to the new max, then we can safely use the newly
2103 computed range for EXPR. This allows us to compute
2104 accurate ranges through many casts. */
2105 if ((vr0.type == VR_RANGE
2106 && !overflow_infinity_range_p (&vr0))
2107 || (vr0.type == VR_VARYING
2108 && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type)))
2110 tree new_min, new_max, orig_min, orig_max;
2112 /* Convert the input operand min/max to OUTER_TYPE. If
2113 the input has no range information, then use the min/max
2114 for the input's type. */
2115 if (vr0.type == VR_RANGE)
2122 orig_min = TYPE_MIN_VALUE (inner_type);
2123 orig_max = TYPE_MAX_VALUE (inner_type);
2126 new_min = fold_convert (outer_type, orig_min);
2127 new_max = fold_convert (outer_type, orig_max);
2129 /* Verify the new min/max values are gimple values and
2130 that they compare equal to the original input's
2132 if (is_gimple_val (new_min)
2133 && is_gimple_val (new_max)
2134 && tree_int_cst_equal (new_min, orig_min)
2135 && tree_int_cst_equal (new_max, orig_max)
2136 && (cmp = compare_values (new_min, new_max)) <= 0
2139 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
2144 /* When converting types of different sizes, set the result to
2145 VARYING. Things like sign extensions and precision loss may
2146 change the range. For instance, if x_3 is of type 'long long
2147 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
2148 is impossible to know at compile time whether y_5 will be
2150 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
2151 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
2153 set_value_range_to_varying (vr);
2158 /* Conversion of a VR_VARYING value to a wider type can result
2159 in a usable range. So wait until after we've handled conversions
2160 before dropping the result to VR_VARYING if we had a source
2161 operand that is VR_VARYING. */
2162 if (vr0.type == VR_VARYING)
2164 set_value_range_to_varying (vr);
2168 /* Apply the operation to each end of the range and see what we end
2170 if (code == NEGATE_EXPR
2171 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
2173 /* NEGATE_EXPR flips the range around. We need to treat
2174 TYPE_MIN_VALUE specially. */
2175 if (is_positive_overflow_infinity (vr0.max))
2176 min = negative_overflow_infinity (TREE_TYPE (expr));
2177 else if (is_negative_overflow_infinity (vr0.max))
2178 min = positive_overflow_infinity (TREE_TYPE (expr));
2179 else if (vr0.max != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2180 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2181 else if (needs_overflow_infinity (TREE_TYPE (expr)))
2183 if (supports_overflow_infinity (TREE_TYPE (expr)))
2184 min = positive_overflow_infinity (TREE_TYPE (expr));
2187 set_value_range_to_varying (vr);
2192 min = TYPE_MIN_VALUE (TREE_TYPE (expr));
2194 if (is_positive_overflow_infinity (vr0.min))
2195 max = negative_overflow_infinity (TREE_TYPE (expr));
2196 else if (is_negative_overflow_infinity (vr0.min))
2197 max = positive_overflow_infinity (TREE_TYPE (expr));
2198 else if (vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2199 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2200 else if (needs_overflow_infinity (TREE_TYPE (expr)))
2202 if (supports_overflow_infinity (TREE_TYPE (expr)))
2203 max = positive_overflow_infinity (TREE_TYPE (expr));
2206 set_value_range_to_varying (vr);
2211 max = TYPE_MIN_VALUE (TREE_TYPE (expr));
2213 else if (code == NEGATE_EXPR
2214 && TYPE_UNSIGNED (TREE_TYPE (expr)))
2216 if (!range_includes_zero_p (&vr0))
2218 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2219 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2223 if (range_is_null (&vr0))
2224 set_value_range_to_null (vr, TREE_TYPE (expr));
2226 set_value_range_to_varying (vr);
2230 else if (code == ABS_EXPR
2231 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
2233 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
2235 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (expr))
2236 && ((vr0.type == VR_RANGE
2237 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
2238 || (vr0.type == VR_ANTI_RANGE
2239 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
2240 && !range_includes_zero_p (&vr0))))
2242 set_value_range_to_varying (vr);
2246 /* ABS_EXPR may flip the range around, if the original range
2247 included negative values. */
2248 if (is_overflow_infinity (vr0.min))
2249 min = positive_overflow_infinity (TREE_TYPE (expr));
2250 else if (vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2251 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2252 else if (!needs_overflow_infinity (TREE_TYPE (expr)))
2253 min = TYPE_MAX_VALUE (TREE_TYPE (expr));
2254 else if (supports_overflow_infinity (TREE_TYPE (expr)))
2255 min = positive_overflow_infinity (TREE_TYPE (expr));
2258 set_value_range_to_varying (vr);
2262 if (is_overflow_infinity (vr0.max))
2263 max = positive_overflow_infinity (TREE_TYPE (expr));
2264 else if (vr0.max != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2265 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2266 else if (!needs_overflow_infinity (TREE_TYPE (expr)))
2267 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
2268 else if (supports_overflow_infinity (TREE_TYPE (expr)))
2269 max = positive_overflow_infinity (TREE_TYPE (expr));
2272 set_value_range_to_varying (vr);
2276 cmp = compare_values (min, max);
2278 /* If a VR_ANTI_RANGEs contains zero, then we have
2279 ~[-INF, min(MIN, MAX)]. */
2280 if (vr0.type == VR_ANTI_RANGE)
2282 if (range_includes_zero_p (&vr0))
2284 /* Take the lower of the two values. */
2288 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
2289 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
2290 flag_wrapv is set and the original anti-range doesn't include
2291 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
2292 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr)))
2294 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
2296 min = (vr0.min != type_min_value
2297 ? int_const_binop (PLUS_EXPR, type_min_value,
2298 integer_one_node, 0)
2303 if (overflow_infinity_range_p (&vr0))
2304 min = negative_overflow_infinity (TREE_TYPE (expr));
2306 min = TYPE_MIN_VALUE (TREE_TYPE (expr));
2311 /* All else has failed, so create the range [0, INF], even for
2312 flag_wrapv since TYPE_MIN_VALUE is in the original
2314 vr0.type = VR_RANGE;
2315 min = build_int_cst (TREE_TYPE (expr), 0);
2316 if (needs_overflow_infinity (TREE_TYPE (expr)))
2318 if (supports_overflow_infinity (TREE_TYPE (expr)))
2319 max = positive_overflow_infinity (TREE_TYPE (expr));
2322 set_value_range_to_varying (vr);
2327 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
2331 /* If the range contains zero then we know that the minimum value in the
2332 range will be zero. */
2333 else if (range_includes_zero_p (&vr0))
2337 min = build_int_cst (TREE_TYPE (expr), 0);
2341 /* If the range was reversed, swap MIN and MAX. */
2352 /* Otherwise, operate on each end of the range. */
2353 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2354 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2356 if (needs_overflow_infinity (TREE_TYPE (expr)))
2358 gcc_assert (code != NEGATE_EXPR && code != ABS_EXPR);
2359 if (is_overflow_infinity (vr0.min))
2361 else if (TREE_OVERFLOW (min))
2363 if (supports_overflow_infinity (TREE_TYPE (expr)))
2364 min = (tree_int_cst_sgn (min) >= 0
2365 ? positive_overflow_infinity (TREE_TYPE (min))
2366 : negative_overflow_infinity (TREE_TYPE (min)));
2369 set_value_range_to_varying (vr);
2374 if (is_overflow_infinity (vr0.max))
2376 else if (TREE_OVERFLOW (max))
2378 if (supports_overflow_infinity (TREE_TYPE (expr)))
2379 max = (tree_int_cst_sgn (max) >= 0
2380 ? positive_overflow_infinity (TREE_TYPE (max))
2381 : negative_overflow_infinity (TREE_TYPE (max)));
2384 set_value_range_to_varying (vr);
2391 cmp = compare_values (min, max);
2392 if (cmp == -2 || cmp == 1)
2394 /* If the new range has its limits swapped around (MIN > MAX),
2395 then the operation caused one of them to wrap around, mark
2396 the new range VARYING. */
2397 set_value_range_to_varying (vr);
2400 set_value_range (vr, vr0.type, min, max, NULL);
2404 /* Extract range information from a conditional expression EXPR based on
2405 the ranges of each of its operands and the expression code. */
2408 extract_range_from_cond_expr (value_range_t *vr, tree expr)
2411 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2412 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2414 /* Get value ranges for each operand. For constant operands, create
2415 a new value range with the operand to simplify processing. */
2416 op0 = COND_EXPR_THEN (expr);
2417 if (TREE_CODE (op0) == SSA_NAME)
2418 vr0 = *(get_value_range (op0));
2419 else if (is_gimple_min_invariant (op0))
2420 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
2422 set_value_range_to_varying (&vr0);
2424 op1 = COND_EXPR_ELSE (expr);
2425 if (TREE_CODE (op1) == SSA_NAME)
2426 vr1 = *(get_value_range (op1));
2427 else if (is_gimple_min_invariant (op1))
2428 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
2430 set_value_range_to_varying (&vr1);
2432 /* The resulting value range is the union of the operand ranges */
2433 vrp_meet (&vr0, &vr1);
2434 copy_value_range (vr, &vr0);
2438 /* Extract range information from a comparison expression EXPR based
2439 on the range of its operand and the expression code. */
2442 extract_range_from_comparison (value_range_t *vr, tree expr)
2445 tree val = vrp_evaluate_conditional_warnv (expr, false, &sop);
2447 /* A disadvantage of using a special infinity as an overflow
2448 representation is that we lose the ability to record overflow
2449 when we don't have an infinity. So we have to ignore a result
2450 which relies on overflow. */
2452 if (val && !is_overflow_infinity (val) && !sop)
2454 /* Since this expression was found on the RHS of an assignment,
2455 its type may be different from _Bool. Convert VAL to EXPR's
2457 val = fold_convert (TREE_TYPE (expr), val);
2458 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
2461 /* The result of a comparison is always true or false. */
2462 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
2466 /* Try to compute a useful range out of expression EXPR and store it
2470 extract_range_from_expr (value_range_t *vr, tree expr)
2472 enum tree_code code = TREE_CODE (expr);
2474 if (code == ASSERT_EXPR)
2475 extract_range_from_assert (vr, expr);
2476 else if (code == SSA_NAME)
2477 extract_range_from_ssa_name (vr, expr);
2478 else if (TREE_CODE_CLASS (code) == tcc_binary
2479 || code == TRUTH_ANDIF_EXPR
2480 || code == TRUTH_ORIF_EXPR
2481 || code == TRUTH_AND_EXPR
2482 || code == TRUTH_OR_EXPR
2483 || code == TRUTH_XOR_EXPR)
2484 extract_range_from_binary_expr (vr, expr);
2485 else if (TREE_CODE_CLASS (code) == tcc_unary)
2486 extract_range_from_unary_expr (vr, expr);
2487 else if (code == COND_EXPR)
2488 extract_range_from_cond_expr (vr, expr);
2489 else if (TREE_CODE_CLASS (code) == tcc_comparison)
2490 extract_range_from_comparison (vr, expr);
2491 else if (is_gimple_min_invariant (expr))
2492 set_value_range (vr, VR_RANGE, expr, expr, NULL);
2494 set_value_range_to_varying (vr);
2496 /* If we got a varying range from the tests above, try a final
2497 time to derive a nonnegative or nonzero range. This time
2498 relying primarily on generic routines in fold in conjunction
2500 if (vr->type == VR_VARYING)
2504 if (INTEGRAL_TYPE_P (TREE_TYPE (expr))
2505 && vrp_expr_computes_nonnegative (expr, &sop))
2506 set_value_range_to_nonnegative (vr, TREE_TYPE (expr),
2507 sop || is_overflow_infinity (expr));
2508 else if (vrp_expr_computes_nonzero (expr, &sop)
2510 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
2514 /* Given a range VR, a LOOP and a variable VAR, determine whether it
2515 would be profitable to adjust VR using scalar evolution information
2516 for VAR. If so, update VR with the new limits. */
2519 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
2522 tree init, step, chrec, tmin, tmax, min, max, type;
2523 enum ev_direction dir;
2525 /* TODO. Don't adjust anti-ranges. An anti-range may provide
2526 better opportunities than a regular range, but I'm not sure. */
2527 if (vr->type == VR_ANTI_RANGE)
2530 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
2531 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
2534 init = initial_condition_in_loop_num (chrec, loop->num);
2535 step = evolution_part_in_loop_num (chrec, loop->num);
2537 /* If STEP is symbolic, we can't know whether INIT will be the
2538 minimum or maximum value in the range. Also, unless INIT is
2539 a simple expression, compare_values and possibly other functions
2540 in tree-vrp won't be able to handle it. */
2541 if (step == NULL_TREE
2542 || !is_gimple_min_invariant (step)
2543 || !valid_value_p (init))
2546 dir = scev_direction (chrec);
2547 if (/* Do not adjust ranges if we do not know whether the iv increases
2548 or decreases, ... */
2549 dir == EV_DIR_UNKNOWN
2550 /* ... or if it may wrap. */
2551 || scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec),
2555 /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of
2556 negative_overflow_infinity and positive_overflow_infinity,
2557 because we have concluded that the loop probably does not
2560 type = TREE_TYPE (var);
2561 if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type))
2562 tmin = lower_bound_in_type (type, type);
2564 tmin = TYPE_MIN_VALUE (type);
2565 if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type))
2566 tmax = upper_bound_in_type (type, type);
2568 tmax = TYPE_MAX_VALUE (type);
2570 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2575 /* For VARYING or UNDEFINED ranges, just about anything we get
2576 from scalar evolutions should be better. */
2578 if (dir == EV_DIR_DECREASES)
2583 /* If we would create an invalid range, then just assume we
2584 know absolutely nothing. This may be over-conservative,
2585 but it's clearly safe, and should happen only in unreachable
2586 parts of code, or for invalid programs. */
2587 if (compare_values (min, max) == 1)
2590 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2592 else if (vr->type == VR_RANGE)
2597 if (dir == EV_DIR_DECREASES)
2599 /* INIT is the maximum value. If INIT is lower than VR->MAX
2600 but no smaller than VR->MIN, set VR->MAX to INIT. */
2601 if (compare_values (init, max) == -1)
2605 /* If we just created an invalid range with the minimum
2606 greater than the maximum, we fail conservatively.
2607 This should happen only in unreachable
2608 parts of code, or for invalid programs. */
2609 if (compare_values (min, max) == 1)
2615 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2616 if (compare_values (init, min) == 1)
2620 /* Again, avoid creating invalid range by failing. */
2621 if (compare_values (min, max) == 1)
2626 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2631 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2633 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2634 all the values in the ranges.
2636 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2638 - Return NULL_TREE if it is not always possible to determine the
2639 value of the comparison.
2641 Also set *STRICT_OVERFLOW_P to indicate whether a range with an
2642 overflow infinity was used in the test. */
2646 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1,
2647 bool *strict_overflow_p)
2649 /* VARYING or UNDEFINED ranges cannot be compared. */
2650 if (vr0->type == VR_VARYING
2651 || vr0->type == VR_UNDEFINED
2652 || vr1->type == VR_VARYING
2653 || vr1->type == VR_UNDEFINED)
2656 /* Anti-ranges need to be handled separately. */
2657 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
2659 /* If both are anti-ranges, then we cannot compute any
2661 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
2664 /* These comparisons are never statically computable. */
2671 /* Equality can be computed only between a range and an
2672 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2673 if (vr0->type == VR_RANGE)
2675 /* To simplify processing, make VR0 the anti-range. */
2676 value_range_t *tmp = vr0;
2681 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
2683 if (compare_values_warnv (vr0->min, vr1->min, strict_overflow_p) == 0
2684 && compare_values_warnv (vr0->max, vr1->max, strict_overflow_p) == 0)
2685 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2690 if (!usable_range_p (vr0, strict_overflow_p)
2691 || !usable_range_p (vr1, strict_overflow_p))
2694 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2695 operands around and change the comparison code. */
2696 if (comp == GT_EXPR || comp == GE_EXPR)
2699 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
2705 if (comp == EQ_EXPR)
2707 /* Equality may only be computed if both ranges represent
2708 exactly one value. */
2709 if (compare_values_warnv (vr0->min, vr0->max, strict_overflow_p) == 0
2710 && compare_values_warnv (vr1->min, vr1->max, strict_overflow_p) == 0)
2712 int cmp_min = compare_values_warnv (vr0->min, vr1->min,
2714 int cmp_max = compare_values_warnv (vr0->max, vr1->max,
2716 if (cmp_min == 0 && cmp_max == 0)
2717 return boolean_true_node;
2718 else if (cmp_min != -2 && cmp_max != -2)
2719 return boolean_false_node;
2721 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2722 else if (compare_values_warnv (vr0->min, vr1->max,
2723 strict_overflow_p) == 1
2724 || compare_values_warnv (vr1->min, vr0->max,
2725 strict_overflow_p) == 1)
2726 return boolean_false_node;
2730 else if (comp == NE_EXPR)
2734 /* If VR0 is completely to the left or completely to the right
2735 of VR1, they are always different. Notice that we need to
2736 make sure that both comparisons yield similar results to
2737 avoid comparing values that cannot be compared at
2739 cmp1 = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
2740 cmp2 = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
2741 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
2742 return boolean_true_node;
2744 /* If VR0 and VR1 represent a single value and are identical,
2746 else if (compare_values_warnv (vr0->min, vr0->max,
2747 strict_overflow_p) == 0
2748 && compare_values_warnv (vr1->min, vr1->max,
2749 strict_overflow_p) == 0
2750 && compare_values_warnv (vr0->min, vr1->min,
2751 strict_overflow_p) == 0
2752 && compare_values_warnv (vr0->max, vr1->max,
2753 strict_overflow_p) == 0)
2754 return boolean_false_node;
2756 /* Otherwise, they may or may not be different. */
2760 else if (comp == LT_EXPR || comp == LE_EXPR)
2764 /* If VR0 is to the left of VR1, return true. */
2765 tst = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
2766 if ((comp == LT_EXPR && tst == -1)
2767 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2769 if (overflow_infinity_range_p (vr0)
2770 || overflow_infinity_range_p (vr1))
2771 *strict_overflow_p = true;
2772 return boolean_true_node;
2775 /* If VR0 is to the right of VR1, return false. */
2776 tst = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
2777 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2778 || (comp == LE_EXPR && tst == 1))
2780 if (overflow_infinity_range_p (vr0)
2781 || overflow_infinity_range_p (vr1))
2782 *strict_overflow_p = true;
2783 return boolean_false_node;
2786 /* Otherwise, we don't know. */
2794 /* Given a value range VR, a value VAL and a comparison code COMP, return
2795 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2796 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2797 always returns false. Return NULL_TREE if it is not always
2798 possible to determine the value of the comparison. Also set
2799 *STRICT_OVERFLOW_P to indicate whether a range with an overflow
2800 infinity was used in the test. */
2803 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val,
2804 bool *strict_overflow_p)
2806 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2809 /* Anti-ranges need to be handled separately. */
2810 if (vr->type == VR_ANTI_RANGE)
2812 /* For anti-ranges, the only predicates that we can compute at
2813 compile time are equality and inequality. */
2820 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2821 if (value_inside_range (val, vr) == 1)
2822 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2827 if (!usable_range_p (vr, strict_overflow_p))
2830 if (comp == EQ_EXPR)
2832 /* EQ_EXPR may only be computed if VR represents exactly
2834 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0)
2836 int cmp = compare_values_warnv (vr->min, val, strict_overflow_p);
2838 return boolean_true_node;
2839 else if (cmp == -1 || cmp == 1 || cmp == 2)
2840 return boolean_false_node;
2842 else if (compare_values_warnv (val, vr->min, strict_overflow_p) == -1
2843 || compare_values_warnv (vr->max, val, strict_overflow_p) == -1)
2844 return boolean_false_node;
2848 else if (comp == NE_EXPR)
2850 /* If VAL is not inside VR, then they are always different. */
2851 if (compare_values_warnv (vr->max, val, strict_overflow_p) == -1
2852 || compare_values_warnv (vr->min, val, strict_overflow_p) == 1)
2853 return boolean_true_node;
2855 /* If VR represents exactly one value equal to VAL, then return
2857 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0
2858 && compare_values_warnv (vr->min, val, strict_overflow_p) == 0)
2859 return boolean_false_node;
2861 /* Otherwise, they may or may not be different. */
2864 else if (comp == LT_EXPR || comp == LE_EXPR)
2868 /* If VR is to the left of VAL, return true. */
2869 tst = compare_values_warnv (vr->max, val, strict_overflow_p);
2870 if ((comp == LT_EXPR && tst == -1)
2871 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2873 if (overflow_infinity_range_p (vr))
2874 *strict_overflow_p = true;
2875 return boolean_true_node;
2878 /* If VR is to the right of VAL, return false. */
2879 tst = compare_values_warnv (vr->min, val, strict_overflow_p);
2880 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2881 || (comp == LE_EXPR && tst == 1))
2883 if (overflow_infinity_range_p (vr))
2884 *strict_overflow_p = true;
2885 return boolean_false_node;
2888 /* Otherwise, we don't know. */
2891 else if (comp == GT_EXPR || comp == GE_EXPR)
2895 /* If VR is to the right of VAL, return true. */
2896 tst = compare_values_warnv (vr->min, val, strict_overflow_p);
2897 if ((comp == GT_EXPR && tst == 1)
2898 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
2900 if (overflow_infinity_range_p (vr))
2901 *strict_overflow_p = true;
2902 return boolean_true_node;
2905 /* If VR is to the left of VAL, return false. */
2906 tst = compare_values_warnv (vr->max, val, strict_overflow_p);
2907 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
2908 || (comp == GE_EXPR && tst == -1))
2910 if (overflow_infinity_range_p (vr))
2911 *strict_overflow_p = true;
2912 return boolean_false_node;
2915 /* Otherwise, we don't know. */
2923 /* Debugging dumps. */
2925 void dump_value_range (FILE *, value_range_t *);
2926 void debug_value_range (value_range_t *);
2927 void dump_all_value_ranges (FILE *);
2928 void debug_all_value_ranges (void);
2929 void dump_vr_equiv (FILE *, bitmap);
2930 void debug_vr_equiv (bitmap);
2933 /* Dump value range VR to FILE. */
2936 dump_value_range (FILE *file, value_range_t *vr)
2939 fprintf (file, "[]");
2940 else if (vr->type == VR_UNDEFINED)
2941 fprintf (file, "UNDEFINED");
2942 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
2944 tree type = TREE_TYPE (vr->min);
2946 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
2948 if (INTEGRAL_TYPE_P (type)
2949 && !TYPE_UNSIGNED (type)
2950 && vr->min == TYPE_MIN_VALUE (type))
2951 fprintf (file, "-INF");
2952 else if (needs_overflow_infinity (type)
2953 && is_negative_overflow_infinity (vr->min))
2954 fprintf (file, "-INF(OVF)");
2956 print_generic_expr (file, vr->min, 0);
2958 fprintf (file, ", ");
2960 if (INTEGRAL_TYPE_P (type)
2961 && vr->max == TYPE_MAX_VALUE (type))
2962 fprintf (file, "+INF");
2963 else if (needs_overflow_infinity (type)
2964 && is_positive_overflow_infinity (vr->max))
2965 fprintf (file, "+INF(OVF)");
2967 print_generic_expr (file, vr->max, 0);
2969 fprintf (file, "]");
2976 fprintf (file, " EQUIVALENCES: { ");
2978 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
2980 print_generic_expr (file, ssa_name (i), 0);
2981 fprintf (file, " ");
2985 fprintf (file, "} (%u elements)", c);
2988 else if (vr->type == VR_VARYING)
2989 fprintf (file, "VARYING");
2991 fprintf (file, "INVALID RANGE");
2995 /* Dump value range VR to stderr. */
2998 debug_value_range (value_range_t *vr)
3000 dump_value_range (stderr, vr);
3001 fprintf (stderr, "\n");
3005 /* Dump value ranges of all SSA_NAMEs to FILE. */
3008 dump_all_value_ranges (FILE *file)
3012 for (i = 0; i < num_ssa_names; i++)
3016 print_generic_expr (file, ssa_name (i), 0);
3017 fprintf (file, ": ");
3018 dump_value_range (file, vr_value[i]);
3019 fprintf (file, "\n");
3023 fprintf (file, "\n");
3027 /* Dump all value ranges to stderr. */
3030 debug_all_value_ranges (void)
3032 dump_all_value_ranges (stderr);
3036 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
3037 create a new SSA name N and return the assertion assignment
3038 'V = ASSERT_EXPR <V, V OP W>'. */
3041 build_assert_expr_for (tree cond, tree v)
3045 gcc_assert (TREE_CODE (v) == SSA_NAME);
3046 n = duplicate_ssa_name (v, NULL_TREE);
3048 if (COMPARISON_CLASS_P (cond))
3050 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
3051 assertion = build_gimple_modify_stmt (n, a);
3053 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
3055 /* Given !V, build the assignment N = false. */
3056 tree op0 = TREE_OPERAND (cond, 0);
3057 gcc_assert (op0 == v);
3058 assertion = build_gimple_modify_stmt (n, boolean_false_node);
3060 else if (TREE_CODE (cond) == SSA_NAME)
3062 /* Given V, build the assignment N = true. */
3063 gcc_assert (v == cond);
3064 assertion = build_gimple_modify_stmt (n, boolean_true_node);
3069 SSA_NAME_DEF_STMT (n) = assertion;
3071 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
3072 operand of the ASSERT_EXPR. Register the new name and the old one
3073 in the replacement table so that we can fix the SSA web after
3074 adding all the ASSERT_EXPRs. */
3075 register_new_name_mapping (n, v);
3081 /* Return false if EXPR is a predicate expression involving floating
3085 fp_predicate (tree expr)
3087 return (COMPARISON_CLASS_P (expr)
3088 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
3092 /* If the range of values taken by OP can be inferred after STMT executes,
3093 return the comparison code (COMP_CODE_P) and value (VAL_P) that
3094 describes the inferred range. Return true if a range could be
3098 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
3101 *comp_code_p = ERROR_MARK;
3103 /* Do not attempt to infer anything in names that flow through
3105 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
3108 /* Similarly, don't infer anything from statements that may throw
3110 if (tree_could_throw_p (stmt))
3113 /* If STMT is the last statement of a basic block with no
3114 successors, there is no point inferring anything about any of its
3115 operands. We would not be able to find a proper insertion point
3116 for the assertion, anyway. */
3117 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
3120 /* We can only assume that a pointer dereference will yield
3121 non-NULL if -fdelete-null-pointer-checks is enabled. */
3122 if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op)))
3124 unsigned num_uses, num_loads, num_stores;
3126 count_uses_and_derefs (op, stmt, &num_uses, &num_loads, &num_stores);
3127 if (num_loads + num_stores > 0)
3129 *val_p = build_int_cst (TREE_TYPE (op), 0);
3130 *comp_code_p = NE_EXPR;
3139 void dump_asserts_for (FILE *, tree);
3140 void debug_asserts_for (tree);
3141 void dump_all_asserts (FILE *);
3142 void debug_all_asserts (void);
3144 /* Dump all the registered assertions for NAME to FILE. */
3147 dump_asserts_for (FILE *file, tree name)
3151 fprintf (file, "Assertions to be inserted for ");
3152 print_generic_expr (file, name, 0);
3153 fprintf (file, "\n");
3155 loc = asserts_for[SSA_NAME_VERSION (name)];
3158 fprintf (file, "\t");
3159 print_generic_expr (file, bsi_stmt (loc->si), 0);
3160 fprintf (file, "\n\tBB #%d", loc->bb->index);
3163 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
3164 loc->e->dest->index);
3165 dump_edge_info (file, loc->e, 0);
3167 fprintf (file, "\n\tPREDICATE: ");
3168 print_generic_expr (file, name, 0);
3169 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
3170 print_generic_expr (file, loc->val, 0);
3171 fprintf (file, "\n\n");
3175 fprintf (file, "\n");
3179 /* Dump all the registered assertions for NAME to stderr. */
3182 debug_asserts_for (tree name)
3184 dump_asserts_for (stderr, name);
3188 /* Dump all the registered assertions for all the names to FILE. */
3191 dump_all_asserts (FILE *file)
3196 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
3197 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3198 dump_asserts_for (file, ssa_name (i));
3199 fprintf (file, "\n");
3203 /* Dump all the registered assertions for all the names to stderr. */
3206 debug_all_asserts (void)
3208 dump_all_asserts (stderr);
3212 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
3213 'NAME COMP_CODE VAL' at a location that dominates block BB or
3214 E->DEST, then register this location as a possible insertion point
3215 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
3217 BB, E and SI provide the exact insertion point for the new
3218 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
3219 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
3220 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
3221 must not be NULL. */
3224 register_new_assert_for (tree name,
3225 enum tree_code comp_code,
3229 block_stmt_iterator si)
3231 assert_locus_t n, loc, last_loc;
3233 basic_block dest_bb;
3235 #if defined ENABLE_CHECKING
3236 gcc_assert (bb == NULL || e == NULL);
3239 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
3240 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
3243 /* The new assertion A will be inserted at BB or E. We need to
3244 determine if the new location is dominated by a previously
3245 registered location for A. If we are doing an edge insertion,
3246 assume that A will be inserted at E->DEST. Note that this is not
3249 If E is a critical edge, it will be split. But even if E is
3250 split, the new block will dominate the same set of blocks that
3253 The reverse, however, is not true, blocks dominated by E->DEST
3254 will not be dominated by the new block created to split E. So,
3255 if the insertion location is on a critical edge, we will not use
3256 the new location to move another assertion previously registered
3257 at a block dominated by E->DEST. */
3258 dest_bb = (bb) ? bb : e->dest;
3260 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
3261 VAL at a block dominating DEST_BB, then we don't need to insert a new
3262 one. Similarly, if the same assertion already exists at a block
3263 dominated by DEST_BB and the new location is not on a critical
3264 edge, then update the existing location for the assertion (i.e.,
3265 move the assertion up in the dominance tree).
3267 Note, this is implemented as a simple linked list because there
3268 should not be more than a handful of assertions registered per
3269 name. If this becomes a performance problem, a table hashed by
3270 COMP_CODE and VAL could be implemented. */
3271 loc = asserts_for[SSA_NAME_VERSION (name)];
3276 if (loc->comp_code == comp_code
3278 || operand_equal_p (loc->val, val, 0)))
3280 /* If the assertion NAME COMP_CODE VAL has already been
3281 registered at a basic block that dominates DEST_BB, then
3282 we don't need to insert the same assertion again. Note
3283 that we don't check strict dominance here to avoid
3284 replicating the same assertion inside the same basic
3285 block more than once (e.g., when a pointer is
3286 dereferenced several times inside a block).
3288 An exception to this rule are edge insertions. If the
3289 new assertion is to be inserted on edge E, then it will
3290 dominate all the other insertions that we may want to
3291 insert in DEST_BB. So, if we are doing an edge
3292 insertion, don't do this dominance check. */
3294 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
3297 /* Otherwise, if E is not a critical edge and DEST_BB
3298 dominates the existing location for the assertion, move
3299 the assertion up in the dominance tree by updating its
3300 location information. */
3301 if ((e == NULL || !EDGE_CRITICAL_P (e))
3302 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
3311 /* Update the last node of the list and move to the next one. */
3316 /* If we didn't find an assertion already registered for
3317 NAME COMP_CODE VAL, add a new one at the end of the list of
3318 assertions associated with NAME. */
3319 n = XNEW (struct assert_locus_d);
3323 n->comp_code = comp_code;
3330 asserts_for[SSA_NAME_VERSION (name)] = n;
3332 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
3335 /* COND is a predicate which uses NAME. Extract a suitable test code
3336 and value and store them into *CODE_P and *VAL_P so the predicate
3337 is normalized to NAME *CODE_P *VAL_P.
3339 If no extraction was possible, return FALSE, otherwise return TRUE.
3341 If INVERT is true, then we invert the result stored into *CODE_P. */
3344 extract_code_and_val_from_cond (tree name, tree cond, bool invert,
3345 enum tree_code *code_p, tree *val_p)
3347 enum tree_code comp_code;
3350 /* Predicates may be a single SSA name or NAME OP VAL. */
3353 /* If the predicate is a name, it must be NAME, in which
3354 case we create the predicate NAME == true or
3355 NAME == false accordingly. */
3356 comp_code = EQ_EXPR;
3357 val = invert ? boolean_false_node : boolean_true_node;
3361 /* Otherwise, we have a comparison of the form NAME COMP VAL
3362 or VAL COMP NAME. */
3363 if (name == TREE_OPERAND (cond, 1))
3365 /* If the predicate is of the form VAL COMP NAME, flip
3366 COMP around because we need to register NAME as the
3367 first operand in the predicate. */
3368 comp_code = swap_tree_comparison (TREE_CODE (cond));
3369 val = TREE_OPERAND (cond, 0);
3373 /* The comparison is of the form NAME COMP VAL, so the
3374 comparison code remains unchanged. */
3375 comp_code = TREE_CODE (cond);
3376 val = TREE_OPERAND (cond, 1);
3379 /* Invert the comparison code as necessary. */
3381 comp_code = invert_tree_comparison (comp_code, 0);
3383 /* VRP does not handle float types. */
3384 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)))
3387 /* Do not register always-false predicates.
3388 FIXME: this works around a limitation in fold() when dealing with
3389 enumerations. Given 'enum { N1, N2 } x;', fold will not
3390 fold 'if (x > N2)' to 'if (0)'. */
3391 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
3392 && INTEGRAL_TYPE_P (TREE_TYPE (val)))
3394 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
3395 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
3397 if (comp_code == GT_EXPR
3399 || compare_values (val, max) == 0))
3402 if (comp_code == LT_EXPR
3404 || compare_values (val, min) == 0))
3408 *code_p = comp_code;
3413 /* OP is an operand of a truth value expression which is known to have
3414 a particular value. Register any asserts for OP and for any
3415 operands in OP's defining statement.
3417 If CODE is EQ_EXPR, then we want to register OP is zero (false),
3418 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
3421 register_edge_assert_for_1 (tree op, enum tree_code code,
3422 edge e, block_stmt_iterator bsi)
3424 bool retval = false;
3425 tree op_def, rhs, val;
3427 /* We only care about SSA_NAMEs. */
3428 if (TREE_CODE (op) != SSA_NAME)
3431 /* We know that OP will have a zero or nonzero value. If OP is used
3432 more than once go ahead and register an assert for OP.
3434 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
3435 it will always be set for OP (because OP is used in a COND_EXPR in
3437 if (!has_single_use (op))
3439 val = build_int_cst (TREE_TYPE (op), 0);
3440 register_new_assert_for (op, code, val, NULL, e, bsi);
3444 /* Now look at how OP is set. If it's set from a comparison,
3445 a truth operation or some bit operations, then we may be able
3446 to register information about the operands of that assignment. */
3447 op_def = SSA_NAME_DEF_STMT (op);
3448 if (TREE_CODE (op_def) != GIMPLE_MODIFY_STMT)
3451 rhs = GIMPLE_STMT_OPERAND (op_def, 1);
3453 if (COMPARISON_CLASS_P (rhs))
3455 bool invert = (code == EQ_EXPR ? true : false);
3456 tree op0 = TREE_OPERAND (rhs, 0);
3457 tree op1 = TREE_OPERAND (rhs, 1);
3459 /* Conditionally register an assert for each SSA_NAME in the
3461 if (TREE_CODE (op0) == SSA_NAME
3462 && !has_single_use (op0)
3463 && extract_code_and_val_from_cond (op0, rhs,
3464 invert, &code, &val))
3466 register_new_assert_for (op0, code, val, NULL, e, bsi);
3470 /* Similarly for the second operand of the comparison. */
3471 if (TREE_CODE (op1) == SSA_NAME
3472 && !has_single_use (op1)
3473 && extract_code_and_val_from_cond (op1, rhs,
3474 invert, &code, &val))
3476 register_new_assert_for (op1, code, val, NULL, e, bsi);
3480 else if ((code == NE_EXPR
3481 && (TREE_CODE (rhs) == TRUTH_AND_EXPR
3482 || TREE_CODE (rhs) == BIT_AND_EXPR))
3484 && (TREE_CODE (rhs) == TRUTH_OR_EXPR
3485 || TREE_CODE (rhs) == BIT_IOR_EXPR)))
3487 /* Recurse on each operand. */
3488 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3490 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 1),
3493 else if (TREE_CODE (rhs) == TRUTH_NOT_EXPR)
3495 /* Recurse, flipping CODE. */
3496 code = invert_tree_comparison (code, false);
3497 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3500 else if (TREE_CODE (rhs) == SSA_NAME)
3502 /* Recurse through the copy. */
3503 retval |= register_edge_assert_for_1 (rhs, code, e, bsi);
3505 else if (TREE_CODE (rhs) == NOP_EXPR
3506 || TREE_CODE (rhs) == CONVERT_EXPR
3507 || TREE_CODE (rhs) == NON_LVALUE_EXPR)
3509 /* Recurse through the type conversion. */
3510 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3517 /* Try to register an edge assertion for SSA name NAME on edge E for
3518 the condition COND contributing to the conditional jump pointed to by SI.
3519 Return true if an assertion for NAME could be registered. */
3522 register_edge_assert_for (tree name, edge e, block_stmt_iterator si, tree cond)
3525 enum tree_code comp_code;
3526 bool retval = false;
3527 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
3529 /* Do not attempt to infer anything in names that flow through
3531 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
3534 if (!extract_code_and_val_from_cond (name, cond, is_else_edge,
3538 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
3539 reachable from E. */
3540 if (TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
3542 register_new_assert_for (name, comp_code, val, NULL, e, si);
3546 /* If COND is effectively an equality test of an SSA_NAME against
3547 the value zero or one, then we may be able to assert values
3548 for SSA_NAMEs which flow into COND. */
3550 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
3551 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
3552 have nonzero value. */
3553 if (((comp_code == EQ_EXPR && integer_onep (val))
3554 || (comp_code == NE_EXPR && integer_zerop (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_AND_EXPR
3560 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_AND_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, NE_EXPR, e, si);
3565 retval |= register_edge_assert_for_1 (op1, NE_EXPR, e, si);
3569 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
3570 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
3572 if (((comp_code == EQ_EXPR && integer_zerop (val))
3573 || (comp_code == NE_EXPR && integer_onep (val))))
3575 tree def_stmt = SSA_NAME_DEF_STMT (name);
3577 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3578 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_OR_EXPR
3579 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_IOR_EXPR))
3581 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3582 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3583 retval |= register_edge_assert_for_1 (op0, EQ_EXPR, e, si);
3584 retval |= register_edge_assert_for_1 (op1, EQ_EXPR, e, si);
3592 static bool find_assert_locations (basic_block bb);
3594 /* Determine whether the outgoing edges of BB should receive an
3595 ASSERT_EXPR for each of the operands of BB's LAST statement.
3596 The last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
3598 If any of the sub-graphs rooted at BB have an interesting use of
3599 the predicate operands, an assert location node is added to the
3600 list of assertions for the corresponding operands. */
3603 find_conditional_asserts (basic_block bb, tree last)
3606 block_stmt_iterator bsi;
3612 need_assert = false;
3613 bsi = bsi_for_stmt (last);
3615 /* Look for uses of the operands in each of the sub-graphs
3616 rooted at BB. We need to check each of the outgoing edges
3617 separately, so that we know what kind of ASSERT_EXPR to
3619 FOR_EACH_EDGE (e, ei, bb->succs)
3624 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
3625 Otherwise, when we finish traversing each of the sub-graphs, we
3626 won't know whether the variables were found in the sub-graphs or
3627 if they had been found in a block upstream from BB.
3629 This is actually a bad idea is some cases, particularly jump
3630 threading. Consider a CFG like the following:
3640 Assume that one or more operands in the conditional at the
3641 end of block 0 are used in a conditional in block 2, but not
3642 anywhere in block 1. In this case we will not insert any
3643 assert statements in block 1, which may cause us to miss
3644 opportunities to optimize, particularly for jump threading. */
3645 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3646 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3648 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3649 to determine if any of the operands in the conditional
3650 predicate are used. */
3652 need_assert |= find_assert_locations (e->dest);
3654 /* Register the necessary assertions for each operand in the
3655 conditional predicate. */
3656 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3657 need_assert |= register_edge_assert_for (op, e, bsi,
3658 COND_EXPR_COND (last));
3661 /* Finally, indicate that we have found the operands in the
3663 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3664 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3670 /* Traverse all the statements in block BB looking for statements that
3671 may generate useful assertions for the SSA names in their operand.
3672 If a statement produces a useful assertion A for name N_i, then the
3673 list of assertions already generated for N_i is scanned to
3674 determine if A is actually needed.
3676 If N_i already had the assertion A at a location dominating the
3677 current location, then nothing needs to be done. Otherwise, the
3678 new location for A is recorded instead.
3680 1- For every statement S in BB, all the variables used by S are
3681 added to bitmap FOUND_IN_SUBGRAPH.
3683 2- If statement S uses an operand N in a way that exposes a known
3684 value range for N, then if N was not already generated by an
3685 ASSERT_EXPR, create a new assert location for N. For instance,
3686 if N is a pointer and the statement dereferences it, we can
3687 assume that N is not NULL.
3689 3- COND_EXPRs are a special case of #2. We can derive range
3690 information from the predicate but need to insert different
3691 ASSERT_EXPRs for each of the sub-graphs rooted at the
3692 conditional block. If the last statement of BB is a conditional
3693 expression of the form 'X op Y', then
3695 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
3697 b) If the conditional is the only entry point to the sub-graph
3698 corresponding to the THEN_CLAUSE, recurse into it. On
3699 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
3700 an ASSERT_EXPR is added for the corresponding variable.
3702 c) Repeat step (b) on the ELSE_CLAUSE.
3704 d) Mark X and Y in FOUND_IN_SUBGRAPH.
3713 In this case, an assertion on the THEN clause is useful to
3714 determine that 'a' is always 9 on that edge. However, an assertion
3715 on the ELSE clause would be unnecessary.
3717 4- If BB does not end in a conditional expression, then we recurse
3718 into BB's dominator children.
3720 At the end of the recursive traversal, every SSA name will have a
3721 list of locations where ASSERT_EXPRs should be added. When a new
3722 location for name N is found, it is registered by calling
3723 register_new_assert_for. That function keeps track of all the
3724 registered assertions to prevent adding unnecessary assertions.
3725 For instance, if a pointer P_4 is dereferenced more than once in a
3726 dominator tree, only the location dominating all the dereference of
3727 P_4 will receive an ASSERT_EXPR.
3729 If this function returns true, then it means that there are names
3730 for which we need to generate ASSERT_EXPRs. Those assertions are
3731 inserted by process_assert_insertions.
3733 TODO. Handle SWITCH_EXPR. */
3736 find_assert_locations (basic_block bb)
3738 block_stmt_iterator si;
3743 if (TEST_BIT (blocks_visited, bb->index))
3746 SET_BIT (blocks_visited, bb->index);
3748 need_assert = false;
3750 /* Traverse all PHI nodes in BB marking used operands. */
3751 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3753 use_operand_p arg_p;
3756 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
3758 tree arg = USE_FROM_PTR (arg_p);
3759 if (TREE_CODE (arg) == SSA_NAME)
3761 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
3762 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
3767 /* Traverse all the statements in BB marking used names and looking
3768 for statements that may infer assertions for their used operands. */
3770 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3775 stmt = bsi_stmt (si);
3777 /* See if we can derive an assertion for any of STMT's operands. */
3778 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
3781 enum tree_code comp_code;
3783 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
3784 the sub-graph of a conditional block, when we return from
3785 this recursive walk, our parent will use the
3786 FOUND_IN_SUBGRAPH bitset to determine if one of the
3787 operands it was looking for was present in the sub-graph. */
3788 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3790 /* If OP is used in such a way that we can infer a value
3791 range for it, and we don't find a previous assertion for
3792 it, create a new assertion location node for OP. */
3793 if (infer_value_range (stmt, op, &comp_code, &value))
3795 /* If we are able to infer a nonzero value range for OP,
3796 then walk backwards through the use-def chain to see if OP
3797 was set via a typecast.
3799 If so, then we can also infer a nonzero value range
3800 for the operand of the NOP_EXPR. */
3801 if (comp_code == NE_EXPR && integer_zerop (value))
3804 tree def_stmt = SSA_NAME_DEF_STMT (t);
3806 while (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3808 (GIMPLE_STMT_OPERAND (def_stmt, 1)) == NOP_EXPR
3810 (TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1),
3813 (TREE_TYPE (TREE_OPERAND
3814 (GIMPLE_STMT_OPERAND (def_stmt,
3817 t = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3818 def_stmt = SSA_NAME_DEF_STMT (t);
3820 /* Note we want to register the assert for the
3821 operand of the NOP_EXPR after SI, not after the
3823 if (! has_single_use (t))
3825 register_new_assert_for (t, comp_code, value,
3832 /* If OP is used only once, namely in this STMT, don't
3833 bother creating an ASSERT_EXPR for it. Such an
3834 ASSERT_EXPR would do nothing but increase compile time. */
3835 if (!has_single_use (op))
3837 register_new_assert_for (op, comp_code, value, bb, NULL, si);
3843 /* Remember the last statement of the block. */
3847 /* If BB's last statement is a conditional expression
3848 involving integer operands, recurse into each of the sub-graphs
3849 rooted at BB to determine if we need to add ASSERT_EXPRs. */
3851 && TREE_CODE (last) == COND_EXPR
3852 && !fp_predicate (COND_EXPR_COND (last))
3853 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
3854 need_assert |= find_conditional_asserts (bb, last);
3856 /* Recurse into the dominator children of BB. */
3857 for (son = first_dom_son (CDI_DOMINATORS, bb);
3859 son = next_dom_son (CDI_DOMINATORS, son))
3860 need_assert |= find_assert_locations (son);
3866 /* Create an ASSERT_EXPR for NAME and insert it in the location
3867 indicated by LOC. Return true if we made any edge insertions. */
3870 process_assert_insertions_for (tree name, assert_locus_t loc)
3872 /* Build the comparison expression NAME_i COMP_CODE VAL. */
3873 tree stmt, cond, assert_expr;
3877 cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
3878 assert_expr = build_assert_expr_for (cond, name);
3882 /* We have been asked to insert the assertion on an edge. This
3883 is used only by COND_EXPR and SWITCH_EXPR assertions. */
3884 #if defined ENABLE_CHECKING
3885 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
3886 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
3889 bsi_insert_on_edge (loc->e, assert_expr);
3893 /* Otherwise, we can insert right after LOC->SI iff the
3894 statement must not be the last statement in the block. */
3895 stmt = bsi_stmt (loc->si);
3896 if (!stmt_ends_bb_p (stmt))
3898 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
3902 /* If STMT must be the last statement in BB, we can only insert new
3903 assertions on the non-abnormal edge out of BB. Note that since
3904 STMT is not control flow, there may only be one non-abnormal edge
3906 FOR_EACH_EDGE (e, ei, loc->bb->succs)
3907 if (!(e->flags & EDGE_ABNORMAL))
3909 bsi_insert_on_edge (e, assert_expr);
3917 /* Process all the insertions registered for every name N_i registered
3918 in NEED_ASSERT_FOR. The list of assertions to be inserted are
3919 found in ASSERTS_FOR[i]. */
3922 process_assert_insertions (void)
3926 bool update_edges_p = false;
3927 int num_asserts = 0;
3929 if (dump_file && (dump_flags & TDF_DETAILS))
3930 dump_all_asserts (dump_file);
3932 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3934 assert_locus_t loc = asserts_for[i];
3939 assert_locus_t next = loc->next;
3940 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
3948 bsi_commit_edge_inserts ();
3950 if (dump_file && (dump_flags & TDF_STATS))
3951 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
3956 /* Traverse the flowgraph looking for conditional jumps to insert range
3957 expressions. These range expressions are meant to provide information
3958 to optimizations that need to reason in terms of value ranges. They
3959 will not be expanded into RTL. For instance, given:
3968 this pass will transform the code into:
3974 x = ASSERT_EXPR <x, x < y>
3979 y = ASSERT_EXPR <y, x <= y>
3983 The idea is that once copy and constant propagation have run, other
3984 optimizations will be able to determine what ranges of values can 'x'
3985 take in different paths of the code, simply by checking the reaching
3986 definition of 'x'. */
3989 insert_range_assertions (void)
3995 found_in_subgraph = sbitmap_alloc (num_ssa_names);
3996 sbitmap_zero (found_in_subgraph);
3998 blocks_visited = sbitmap_alloc (last_basic_block);
3999 sbitmap_zero (blocks_visited);
4001 need_assert_for = BITMAP_ALLOC (NULL);
4002 asserts_for = XCNEWVEC (assert_locus_t, num_ssa_names);
4004 calculate_dominance_info (CDI_DOMINATORS);
4006 update_ssa_p = false;
4007 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
4008 if (find_assert_locations (e->dest))
4009 update_ssa_p = true;
4013 process_assert_insertions ();
4014 update_ssa (TODO_update_ssa_no_phi);
4017 if (dump_file && (dump_flags & TDF_DETAILS))
4019 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
4020 dump_function_to_file (current_function_decl, dump_file, dump_flags);
4023 sbitmap_free (found_in_subgraph);
4025 BITMAP_FREE (need_assert_for);
4028 /* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays
4029 and "struct" hacks. If VRP can determine that the
4030 array subscript is a constant, check if it is outside valid
4031 range. If the array subscript is a RANGE, warn if it is
4032 non-overlapping with valid range.
4033 IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */
4036 check_array_ref (tree ref, location_t* locus, bool ignore_off_by_one)
4038 value_range_t* vr = NULL;
4039 tree low_sub, up_sub;
4040 tree low_bound, up_bound = array_ref_up_bound (ref);
4042 low_sub = up_sub = TREE_OPERAND (ref, 1);
4044 if (!up_bound || !locus || TREE_NO_WARNING (ref)
4045 || TREE_CODE (up_bound) != INTEGER_CST
4046 /* Can not check flexible arrays. */
4047 || (TYPE_SIZE (TREE_TYPE (ref)) == NULL_TREE
4048 && TYPE_DOMAIN (TREE_TYPE (ref)) != NULL_TREE
4049 && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (ref))) == NULL_TREE)
4050 /* Accesses after the end of arrays of size 0 (gcc
4051 extension) and 1 are likely intentional ("struct
4053 || compare_tree_int (up_bound, 1) <= 0)
4056 low_bound = array_ref_low_bound (ref);
4058 if (TREE_CODE (low_sub) == SSA_NAME)
4060 vr = get_value_range (low_sub);
4061 if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
4063 low_sub = vr->type == VR_RANGE ? vr->max : vr->min;
4064 up_sub = vr->type == VR_RANGE ? vr->min : vr->max;
4068 if (vr && vr->type == VR_ANTI_RANGE)
4070 if (TREE_CODE (up_sub) == INTEGER_CST
4071 && tree_int_cst_lt (up_bound, up_sub)
4072 && TREE_CODE (low_sub) == INTEGER_CST
4073 && tree_int_cst_lt (low_sub, low_bound))
4075 warning (OPT_Warray_bounds,
4076 "%Harray subscript is outside array bounds", locus);
4077 TREE_NO_WARNING (ref) = 1;
4080 else if (TREE_CODE (up_sub) == INTEGER_CST
4081 && tree_int_cst_lt (up_bound, up_sub)
4082 && !tree_int_cst_equal (up_bound, up_sub)
4083 && (!ignore_off_by_one
4084 || !tree_int_cst_equal (int_const_binop (PLUS_EXPR,
4090 warning (OPT_Warray_bounds, "%Harray subscript is above array bounds",
4092 TREE_NO_WARNING (ref) = 1;
4094 else if (TREE_CODE (low_sub) == INTEGER_CST
4095 && tree_int_cst_lt (low_sub, low_bound))
4097 warning (OPT_Warray_bounds, "%Harray subscript is below array bounds",
4099 TREE_NO_WARNING (ref) = 1;
4103 /* walk_tree() callback that checks if *TP is
4104 an ARRAY_REF inside an ADDR_EXPR (in which an array
4105 subscript one outside the valid range is allowed). Call
4106 check_array_ref for each ARRAY_REF found. The location is
4110 check_array_bounds (tree *tp, int *walk_subtree, void *data)
4113 tree stmt = (tree)data;
4114 location_t *location = EXPR_LOCUS (stmt);
4116 *walk_subtree = TRUE;
4118 if (TREE_CODE (t) == ARRAY_REF)
4119 check_array_ref (t, location, false /*ignore_off_by_one*/);
4120 else if (TREE_CODE (t) == ADDR_EXPR)
4124 t = TREE_OPERAND (t, 0);
4126 /* Don't warn on statements like
4128 ssa_name = 500 + &array[-200]
4132 ssa_name = &array[-200]
4133 other_name = ssa_name + 300;
4136 produced by other optimizing passes. */
4138 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
4139 && BINARY_CLASS_P (GIMPLE_STMT_OPERAND (stmt, 1)))
4140 *walk_subtree = FALSE;
4142 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
4143 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 0)) == SSA_NAME
4144 && single_imm_use (GIMPLE_STMT_OPERAND (stmt, 0), &op, &use_stmt)
4145 && TREE_CODE (use_stmt) == GIMPLE_MODIFY_STMT
4146 && BINARY_CLASS_P (GIMPLE_STMT_OPERAND (use_stmt, 1)))
4147 *walk_subtree = FALSE;
4149 while (*walk_subtree && handled_component_p (t))
4151 if (TREE_CODE (t) == ARRAY_REF)
4152 check_array_ref (t, location, true /*ignore_off_by_one*/);
4153 t = TREE_OPERAND (t, 0);
4155 *walk_subtree = FALSE;
4161 /* Walk over all statements of all reachable BBs and call check_array_bounds
4165 check_all_array_refs (void)
4168 block_stmt_iterator si;
4172 /* Skip bb's that are clearly unreachable. */
4173 if (single_pred_p (bb))
4175 basic_block pred_bb = EDGE_PRED (bb, 0)->src;
4176 tree ls = NULL_TREE;
4178 if (!bsi_end_p (bsi_last (pred_bb)))
4179 ls = bsi_stmt (bsi_last (pred_bb));
4181 if (ls && TREE_CODE (ls) == COND_EXPR
4182 && ((COND_EXPR_COND (ls) == boolean_false_node
4183 && (EDGE_PRED (bb, 0)->flags & EDGE_TRUE_VALUE))
4184 || (COND_EXPR_COND (ls) == boolean_true_node
4185 && (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE))))
4188 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
4189 walk_tree (bsi_stmt_ptr (si), check_array_bounds,
4190 bsi_stmt (si), NULL);
4194 /* Convert range assertion expressions into the implied copies and
4195 copy propagate away the copies. Doing the trivial copy propagation
4196 here avoids the need to run the full copy propagation pass after
4199 FIXME, this will eventually lead to copy propagation removing the
4200 names that had useful range information attached to them. For
4201 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
4202 then N_i will have the range [3, +INF].
4204 However, by converting the assertion into the implied copy
4205 operation N_i = N_j, we will then copy-propagate N_j into the uses
4206 of N_i and lose the range information. We may want to hold on to
4207 ASSERT_EXPRs a little while longer as the ranges could be used in
4208 things like jump threading.
4210 The problem with keeping ASSERT_EXPRs around is that passes after
4211 VRP need to handle them appropriately.
4213 Another approach would be to make the range information a first
4214 class property of the SSA_NAME so that it can be queried from
4215 any pass. This is made somewhat more complex by the need for
4216 multiple ranges to be associated with one SSA_NAME. */
4219 remove_range_assertions (void)
4222 block_stmt_iterator si;
4224 /* Note that the BSI iterator bump happens at the bottom of the
4225 loop and no bump is necessary if we're removing the statement
4226 referenced by the current BSI. */
4228 for (si = bsi_start (bb); !bsi_end_p (si);)
4230 tree stmt = bsi_stmt (si);
4233 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
4234 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ASSERT_EXPR)
4236 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1), var;
4237 tree cond = fold (ASSERT_EXPR_COND (rhs));
4238 use_operand_p use_p;
4239 imm_use_iterator iter;
4241 gcc_assert (cond != boolean_false_node);
4243 /* Propagate the RHS into every use of the LHS. */
4244 var = ASSERT_EXPR_VAR (rhs);
4245 FOR_EACH_IMM_USE_STMT (use_stmt, iter,
4246 GIMPLE_STMT_OPERAND (stmt, 0))
4247 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
4249 SET_USE (use_p, var);
4250 gcc_assert (TREE_CODE (var) == SSA_NAME);
4253 /* And finally, remove the copy, it is not needed. */
4254 bsi_remove (&si, true);
4255 release_defs (stmt);
4261 sbitmap_free (blocks_visited);
4265 /* Return true if STMT is interesting for VRP. */
4268 stmt_interesting_for_vrp (tree stmt)
4270 if (TREE_CODE (stmt) == PHI_NODE
4271 && is_gimple_reg (PHI_RESULT (stmt))
4272 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
4273 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
4275 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4277 tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
4278 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4280 /* In general, assignments with virtual operands are not useful
4281 for deriving ranges, with the obvious exception of calls to
4282 builtin functions. */
4283 if (TREE_CODE (lhs) == SSA_NAME
4284 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
4285 || POINTER_TYPE_P (TREE_TYPE (lhs)))
4286 && ((TREE_CODE (rhs) == CALL_EXPR
4287 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
4288 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs), 0))
4289 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
4290 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)))
4293 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
4300 /* Initialize local data structures for VRP. */
4303 vrp_initialize (void)
4307 vr_value = XCNEWVEC (value_range_t *, num_ssa_names);
4311 block_stmt_iterator si;
4314 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4316 if (!stmt_interesting_for_vrp (phi))
4318 tree lhs = PHI_RESULT (phi);
4319 set_value_range_to_varying (get_value_range (lhs));
4320 DONT_SIMULATE_AGAIN (phi) = true;
4323 DONT_SIMULATE_AGAIN (phi) = false;
4326 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
4328 tree stmt = bsi_stmt (si);
4330 if (!stmt_interesting_for_vrp (stmt))
4334 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
4335 set_value_range_to_varying (get_value_range (def));
4336 DONT_SIMULATE_AGAIN (stmt) = true;
4340 DONT_SIMULATE_AGAIN (stmt) = false;
4347 /* Visit assignment STMT. If it produces an interesting range, record
4348 the SSA name in *OUTPUT_P. */
4350 static enum ssa_prop_result
4351 vrp_visit_assignment (tree stmt, tree *output_p)
4356 lhs = GIMPLE_STMT_OPERAND (stmt, 0);
4357 rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4359 /* We only keep track of ranges in integral and pointer types. */
4360 if (TREE_CODE (lhs) == SSA_NAME
4361 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
4362 /* It is valid to have NULL MIN/MAX values on a type. See
4363 build_range_type. */
4364 && TYPE_MIN_VALUE (TREE_TYPE (lhs))
4365 && TYPE_MAX_VALUE (TREE_TYPE (lhs)))
4366 || POINTER_TYPE_P (TREE_TYPE (lhs))))
4369 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
4371 extract_range_from_expr (&new_vr, rhs);
4373 /* If STMT is inside a loop, we may be able to know something
4374 else about the range of LHS by examining scalar evolution
4376 if (current_loops && (l = loop_containing_stmt (stmt)))
4377 adjust_range_with_scev (&new_vr, l, stmt, lhs);
4379 if (update_value_range (lhs, &new_vr))
4383 if (dump_file && (dump_flags & TDF_DETAILS))
4385 fprintf (dump_file, "Found new range for ");
4386 print_generic_expr (dump_file, lhs, 0);
4387 fprintf (dump_file, ": ");
4388 dump_value_range (dump_file, &new_vr);
4389 fprintf (dump_file, "\n\n");
4392 if (new_vr.type == VR_VARYING)
4393 return SSA_PROP_VARYING;
4395 return SSA_PROP_INTERESTING;
4398 return SSA_PROP_NOT_INTERESTING;
4401 /* Every other statement produces no useful ranges. */
4402 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
4403 set_value_range_to_varying (get_value_range (def));
4405 return SSA_PROP_VARYING;
4409 /* Compare all the value ranges for names equivalent to VAR with VAL
4410 using comparison code COMP. Return the same value returned by
4411 compare_range_with_value, including the setting of
4412 *STRICT_OVERFLOW_P. */
4415 compare_name_with_value (enum tree_code comp, tree var, tree val,
4416 bool *strict_overflow_p)
4422 int used_strict_overflow;
4424 t = retval = NULL_TREE;
4426 /* Get the set of equivalences for VAR. */
4427 e = get_value_range (var)->equiv;
4429 /* Add VAR to its own set of equivalences so that VAR's value range
4430 is processed by this loop (otherwise, we would have to replicate
4431 the body of the loop just to check VAR's value range). */
4432 bitmap_set_bit (e, SSA_NAME_VERSION (var));
4434 /* Start at -1. Set it to 0 if we do a comparison without relying
4435 on overflow, or 1 if all comparisons rely on overflow. */
4436 used_strict_overflow = -1;
4438 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
4442 value_range_t equiv_vr = *(vr_value[i]);
4444 /* If name N_i does not have a valid range, use N_i as its own
4445 range. This allows us to compare against names that may
4446 have N_i in their ranges. */
4447 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
4449 equiv_vr.type = VR_RANGE;
4450 equiv_vr.min = ssa_name (i);
4451 equiv_vr.max = ssa_name (i);
4455 t = compare_range_with_value (comp, &equiv_vr, val, &sop);
4458 /* If we get different answers from different members
4459 of the equivalence set this check must be in a dead
4460 code region. Folding it to a trap representation
4461 would be correct here. For now just return don't-know. */
4471 used_strict_overflow = 0;
4472 else if (used_strict_overflow < 0)
4473 used_strict_overflow = 1;
4477 /* Remove VAR from its own equivalence set. */
4478 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
4482 if (used_strict_overflow > 0)
4483 *strict_overflow_p = true;
4487 /* We couldn't find a non-NULL value for the predicate. */
4492 /* Given a comparison code COMP and names N1 and N2, compare all the
4493 ranges equivalent to N1 against all the ranges equivalent to N2
4494 to determine the value of N1 COMP N2. Return the same value
4495 returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate
4496 whether we relied on an overflow infinity in the comparison. */
4500 compare_names (enum tree_code comp, tree n1, tree n2,
4501 bool *strict_overflow_p)
4505 bitmap_iterator bi1, bi2;
4507 int used_strict_overflow;
4509 /* Compare the ranges of every name equivalent to N1 against the
4510 ranges of every name equivalent to N2. */
4511 e1 = get_value_range (n1)->equiv;
4512 e2 = get_value_range (n2)->equiv;
4514 /* Add N1 and N2 to their own set of equivalences to avoid
4515 duplicating the body of the loop just to check N1 and N2
4517 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
4518 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
4520 /* If the equivalence sets have a common intersection, then the two
4521 names can be compared without checking their ranges. */
4522 if (bitmap_intersect_p (e1, e2))
4524 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4525 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4527 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
4529 : boolean_false_node;
4532 /* Start at -1. Set it to 0 if we do a comparison without relying
4533 on overflow, or 1 if all comparisons rely on overflow. */
4534 used_strict_overflow = -1;
4536 /* Otherwise, compare all the equivalent ranges. First, add N1 and
4537 N2 to their own set of equivalences to avoid duplicating the body
4538 of the loop just to check N1 and N2 ranges. */
4539 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
4541 value_range_t vr1 = *(vr_value[i1]);
4543 /* If the range is VARYING or UNDEFINED, use the name itself. */
4544 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
4546 vr1.type = VR_RANGE;
4547 vr1.min = ssa_name (i1);
4548 vr1.max = ssa_name (i1);
4551 t = retval = NULL_TREE;
4552 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
4556 value_range_t vr2 = *(vr_value[i2]);
4558 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
4560 vr2.type = VR_RANGE;
4561 vr2.min = ssa_name (i2);
4562 vr2.max = ssa_name (i2);
4565 t = compare_ranges (comp, &vr1, &vr2, &sop);
4568 /* If we get different answers from different members
4569 of the equivalence set this check must be in a dead
4570 code region. Folding it to a trap representation
4571 would be correct here. For now just return don't-know. */
4575 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4576 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4582 used_strict_overflow = 0;
4583 else if (used_strict_overflow < 0)
4584 used_strict_overflow = 1;
4590 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4591 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4592 if (used_strict_overflow > 0)
4593 *strict_overflow_p = true;
4598 /* None of the equivalent ranges are useful in computing this
4600 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4601 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4606 /* Given a conditional predicate COND, try to determine if COND yields
4607 true or false based on the value ranges of its operands. Return
4608 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
4609 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
4610 NULL if the conditional cannot be evaluated at compile time.
4612 If USE_EQUIV_P is true, the ranges of all the names equivalent with
4613 the operands in COND are used when trying to compute its value.
4614 This is only used during final substitution. During propagation,
4615 we only check the range of each variable and not its equivalents.
4617 Set *STRICT_OVERFLOW_P to indicate whether we relied on an overflow
4618 infinity to produce the result. */
4621 vrp_evaluate_conditional_warnv (tree cond, bool use_equiv_p,
4622 bool *strict_overflow_p)
4624 gcc_assert (TREE_CODE (cond) == SSA_NAME
4625 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
4627 if (TREE_CODE (cond) == SSA_NAME)
4633 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node,
4637 value_range_t *vr = get_value_range (cond);
4638 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node,
4642 /* If COND has a known boolean range, return it. */
4646 /* Otherwise, if COND has a symbolic range of exactly one value,
4648 vr = get_value_range (cond);
4649 if (vr->type == VR_RANGE && vr->min == vr->max)
4654 tree op0 = TREE_OPERAND (cond, 0);
4655 tree op1 = TREE_OPERAND (cond, 1);
4657 /* We only deal with integral and pointer types. */
4658 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
4659 && !POINTER_TYPE_P (TREE_TYPE (op0)))
4664 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
4665 return compare_names (TREE_CODE (cond), op0, op1,
4667 else if (TREE_CODE (op0) == SSA_NAME)
4668 return compare_name_with_value (TREE_CODE (cond), op0, op1,
4670 else if (TREE_CODE (op1) == SSA_NAME)
4671 return (compare_name_with_value
4672 (swap_tree_comparison (TREE_CODE (cond)), op1, op0,
4673 strict_overflow_p));
4677 value_range_t *vr0, *vr1;
4679 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
4680 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
4683 return compare_ranges (TREE_CODE (cond), vr0, vr1,
4685 else if (vr0 && vr1 == NULL)
4686 return compare_range_with_value (TREE_CODE (cond), vr0, op1,
4688 else if (vr0 == NULL && vr1)
4689 return (compare_range_with_value
4690 (swap_tree_comparison (TREE_CODE (cond)), vr1, op0,
4691 strict_overflow_p));
4695 /* Anything else cannot be computed statically. */
4699 /* Given COND within STMT, try to simplify it based on value range
4700 information. Return NULL if the conditional can not be evaluated.
4701 The ranges of all the names equivalent with the operands in COND
4702 will be used when trying to compute the value. If the result is
4703 based on undefined signed overflow, issue a warning if
4707 vrp_evaluate_conditional (tree cond, tree stmt)
4713 ret = vrp_evaluate_conditional_warnv (cond, true, &sop);
4717 enum warn_strict_overflow_code wc;
4718 const char* warnmsg;
4720 if (is_gimple_min_invariant (ret))
4722 wc = WARN_STRICT_OVERFLOW_CONDITIONAL;
4723 warnmsg = G_("assuming signed overflow does not occur when "
4724 "simplifying conditional to constant");
4728 wc = WARN_STRICT_OVERFLOW_COMPARISON;
4729 warnmsg = G_("assuming signed overflow does not occur when "
4730 "simplifying conditional");
4733 if (issue_strict_overflow_warning (wc))
4737 if (!EXPR_HAS_LOCATION (stmt))
4738 locus = input_location;
4740 locus = EXPR_LOCATION (stmt);
4741 warning (OPT_Wstrict_overflow, "%H%s", &locus, warnmsg);
4749 /* Visit conditional statement STMT. If we can determine which edge
4750 will be taken out of STMT's basic block, record it in
4751 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
4752 SSA_PROP_VARYING. */
4754 static enum ssa_prop_result
4755 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
4760 *taken_edge_p = NULL;
4762 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
4763 add ASSERT_EXPRs for them. */
4764 if (TREE_CODE (stmt) == SWITCH_EXPR)
4765 return SSA_PROP_VARYING;
4767 cond = COND_EXPR_COND (stmt);
4769 if (dump_file && (dump_flags & TDF_DETAILS))
4774 fprintf (dump_file, "\nVisiting conditional with predicate: ");
4775 print_generic_expr (dump_file, cond, 0);
4776 fprintf (dump_file, "\nWith known ranges\n");
4778 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
4780 fprintf (dump_file, "\t");
4781 print_generic_expr (dump_file, use, 0);
4782 fprintf (dump_file, ": ");
4783 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
4786 fprintf (dump_file, "\n");
4789 /* Compute the value of the predicate COND by checking the known
4790 ranges of each of its operands.
4792 Note that we cannot evaluate all the equivalent ranges here
4793 because those ranges may not yet be final and with the current
4794 propagation strategy, we cannot determine when the value ranges
4795 of the names in the equivalence set have changed.
4797 For instance, given the following code fragment
4801 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
4805 Assume that on the first visit to i_14, i_5 has the temporary
4806 range [8, 8] because the second argument to the PHI function is
4807 not yet executable. We derive the range ~[0, 0] for i_14 and the
4808 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
4809 the first time, since i_14 is equivalent to the range [8, 8], we
4810 determine that the predicate is always false.
4812 On the next round of propagation, i_13 is determined to be
4813 VARYING, which causes i_5 to drop down to VARYING. So, another
4814 visit to i_14 is scheduled. In this second visit, we compute the
4815 exact same range and equivalence set for i_14, namely ~[0, 0] and
4816 { i_5 }. But we did not have the previous range for i_5
4817 registered, so vrp_visit_assignment thinks that the range for
4818 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
4819 is not visited again, which stops propagation from visiting
4820 statements in the THEN clause of that if().
4822 To properly fix this we would need to keep the previous range
4823 value for the names in the equivalence set. This way we would've
4824 discovered that from one visit to the other i_5 changed from
4825 range [8, 8] to VR_VARYING.
4827 However, fixing this apparent limitation may not be worth the
4828 additional checking. Testing on several code bases (GCC, DLV,
4829 MICO, TRAMP3D and SPEC2000) showed that doing this results in
4830 4 more predicates folded in SPEC. */
4832 val = vrp_evaluate_conditional_warnv (cond, false, &sop);
4836 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
4839 if (dump_file && (dump_flags & TDF_DETAILS))
4841 "\nIgnoring predicate evaluation because "
4842 "it assumes that signed overflow is undefined");
4847 if (dump_file && (dump_flags & TDF_DETAILS))
4849 fprintf (dump_file, "\nPredicate evaluates to: ");
4850 if (val == NULL_TREE)
4851 fprintf (dump_file, "DON'T KNOW\n");
4853 print_generic_stmt (dump_file, val, 0);
4856 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
4860 /* Evaluate statement STMT. If the statement produces a useful range,
4861 return SSA_PROP_INTERESTING and record the SSA name with the
4862 interesting range into *OUTPUT_P.
4864 If STMT is a conditional branch and we can determine its truth
4865 value, the taken edge is recorded in *TAKEN_EDGE_P.
4867 If STMT produces a varying value, return SSA_PROP_VARYING. */
4869 static enum ssa_prop_result
4870 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
4876 if (dump_file && (dump_flags & TDF_DETAILS))
4878 fprintf (dump_file, "\nVisiting statement:\n");
4879 print_generic_stmt (dump_file, stmt, dump_flags);
4880 fprintf (dump_file, "\n");
4883 ann = stmt_ann (stmt);
4884 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4886 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4888 /* In general, assignments with virtual operands are not useful
4889 for deriving ranges, with the obvious exception of calls to
4890 builtin functions. */
4891 if ((TREE_CODE (rhs) == CALL_EXPR
4892 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
4893 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs), 0))
4894 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
4895 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
4896 return vrp_visit_assignment (stmt, output_p);
4898 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
4899 return vrp_visit_cond_stmt (stmt, taken_edge_p);
4901 /* All other statements produce nothing of interest for VRP, so mark
4902 their outputs varying and prevent further simulation. */
4903 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
4904 set_value_range_to_varying (get_value_range (def));
4906 return SSA_PROP_VARYING;
4910 /* Meet operation for value ranges. Given two value ranges VR0 and
4911 VR1, store in VR0 a range that contains both VR0 and VR1. This
4912 may not be the smallest possible such range. */
4915 vrp_meet (value_range_t *vr0, value_range_t *vr1)
4917 if (vr0->type == VR_UNDEFINED)
4919 copy_value_range (vr0, vr1);
4923 if (vr1->type == VR_UNDEFINED)
4925 /* Nothing to do. VR0 already has the resulting range. */
4929 if (vr0->type == VR_VARYING)
4931 /* Nothing to do. VR0 already has the resulting range. */
4935 if (vr1->type == VR_VARYING)
4937 set_value_range_to_varying (vr0);
4941 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
4946 /* Compute the convex hull of the ranges. The lower limit of
4947 the new range is the minimum of the two ranges. If they
4948 cannot be compared, then give up. */
4949 cmp = compare_values (vr0->min, vr1->min);
4950 if (cmp == 0 || cmp == 1)
4957 /* Similarly, the upper limit of the new range is the maximum
4958 of the two ranges. If they cannot be compared, then
4960 cmp = compare_values (vr0->max, vr1->max);
4961 if (cmp == 0 || cmp == -1)
4968 /* The resulting set of equivalences is the intersection of
4970 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4971 bitmap_and_into (vr0->equiv, vr1->equiv);
4972 else if (vr0->equiv && !vr1->equiv)
4973 bitmap_clear (vr0->equiv);
4975 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
4977 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
4979 /* Two anti-ranges meet only if their complements intersect.
4980 Only handle the case of identical ranges. */
4981 if (compare_values (vr0->min, vr1->min) == 0
4982 && compare_values (vr0->max, vr1->max) == 0
4983 && compare_values (vr0->min, vr0->max) == 0)
4985 /* The resulting set of equivalences is the intersection of
4987 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4988 bitmap_and_into (vr0->equiv, vr1->equiv);
4989 else if (vr0->equiv && !vr1->equiv)
4990 bitmap_clear (vr0->equiv);
4995 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
4997 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
4998 only handle the case where the ranges have an empty intersection.
4999 The result of the meet operation is the anti-range. */
5000 if (!symbolic_range_p (vr0)
5001 && !symbolic_range_p (vr1)
5002 && !value_ranges_intersect_p (vr0, vr1))
5004 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
5005 set. We need to compute the intersection of the two
5006 equivalence sets. */
5007 if (vr1->type == VR_ANTI_RANGE)
5008 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
5010 /* The resulting set of equivalences is the intersection of
5012 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
5013 bitmap_and_into (vr0->equiv, vr1->equiv);
5014 else if (vr0->equiv && !vr1->equiv)
5015 bitmap_clear (vr0->equiv);
5026 /* Failed to find an efficient meet. Before giving up and setting
5027 the result to VARYING, see if we can at least derive a useful
5028 anti-range. FIXME, all this nonsense about distinguishing
5029 anti-ranges from ranges is necessary because of the odd
5030 semantics of range_includes_zero_p and friends. */
5031 if (!symbolic_range_p (vr0)
5032 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
5033 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
5034 && !symbolic_range_p (vr1)
5035 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
5036 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
5038 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
5040 /* Since this meet operation did not result from the meeting of
5041 two equivalent names, VR0 cannot have any equivalences. */
5043 bitmap_clear (vr0->equiv);
5046 set_value_range_to_varying (vr0);
5050 /* Visit all arguments for PHI node PHI that flow through executable
5051 edges. If a valid value range can be derived from all the incoming
5052 value ranges, set a new range for the LHS of PHI. */
5054 static enum ssa_prop_result
5055 vrp_visit_phi_node (tree phi)
5058 tree lhs = PHI_RESULT (phi);
5059 value_range_t *lhs_vr = get_value_range (lhs);
5060 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
5061 bool all_const = true;
5063 copy_value_range (&vr_result, lhs_vr);
5065 if (dump_file && (dump_flags & TDF_DETAILS))
5067 fprintf (dump_file, "\nVisiting PHI node: ");
5068 print_generic_expr (dump_file, phi, dump_flags);
5071 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
5073 edge e = PHI_ARG_EDGE (phi, i);
5075 if (dump_file && (dump_flags & TDF_DETAILS))
5078 "\n Argument #%d (%d -> %d %sexecutable)\n",
5079 i, e->src->index, e->dest->index,
5080 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
5083 if (e->flags & EDGE_EXECUTABLE)
5085 tree arg = PHI_ARG_DEF (phi, i);
5086 value_range_t vr_arg;
5088 if (TREE_CODE (arg) == SSA_NAME)
5090 vr_arg = *(get_value_range (arg));
5095 vr_arg.type = VR_RANGE;
5098 vr_arg.equiv = NULL;
5101 if (dump_file && (dump_flags & TDF_DETAILS))
5103 fprintf (dump_file, "\t");
5104 print_generic_expr (dump_file, arg, dump_flags);
5105 fprintf (dump_file, "\n\tValue: ");
5106 dump_value_range (dump_file, &vr_arg);
5107 fprintf (dump_file, "\n");
5110 vrp_meet (&vr_result, &vr_arg);
5112 if (vr_result.type == VR_VARYING)
5117 if (vr_result.type == VR_VARYING)
5120 /* To prevent infinite iterations in the algorithm, derive ranges
5121 when the new value is slightly bigger or smaller than the
5123 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE
5126 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
5128 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
5129 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
5131 /* If the new minimum is smaller or larger than the previous
5132 one, go all the way to -INF. In the first case, to avoid
5133 iterating millions of times to reach -INF, and in the
5134 other case to avoid infinite bouncing between different
5136 if (cmp_min > 0 || cmp_min < 0)
5138 /* If we will end up with a (-INF, +INF) range, set it
5140 if (is_positive_overflow_infinity (vr_result.max)
5142 == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max))))
5145 if (!needs_overflow_infinity (TREE_TYPE (vr_result.min)))
5146 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
5147 else if (supports_overflow_infinity (TREE_TYPE (vr_result.min)))
5149 negative_overflow_infinity (TREE_TYPE (vr_result.min));
5154 /* Similarly, if the new maximum is smaller or larger than
5155 the previous one, go all the way to +INF. */
5156 if (cmp_max < 0 || cmp_max > 0)
5158 /* If we will end up with a (-INF, +INF) range, set it
5160 if (is_negative_overflow_infinity (vr_result.min)
5162 == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))))
5165 if (!needs_overflow_infinity (TREE_TYPE (vr_result.max)))
5166 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
5167 else if (supports_overflow_infinity (TREE_TYPE (vr_result.max)))
5169 positive_overflow_infinity (TREE_TYPE (vr_result.max));
5176 /* If the new range is different than the previous value, keep
5178 if (update_value_range (lhs, &vr_result))
5179 return SSA_PROP_INTERESTING;
5181 /* Nothing changed, don't add outgoing edges. */
5182 return SSA_PROP_NOT_INTERESTING;
5184 /* No match found. Set the LHS to VARYING. */
5186 set_value_range_to_varying (lhs_vr);
5187 return SSA_PROP_VARYING;
5190 /* Simplify a division or modulo operator to a right shift or
5191 bitwise and if the first operand is unsigned or is greater
5192 than zero and the second operand is an exact power of two. */
5195 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
5198 tree op = TREE_OPERAND (rhs, 0);
5199 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
5201 if (TYPE_UNSIGNED (TREE_TYPE (op)))
5203 val = integer_one_node;
5209 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node, &sop);
5213 && integer_onep (val)
5214 && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
5218 if (!EXPR_HAS_LOCATION (stmt))
5219 locus = input_location;
5221 locus = EXPR_LOCATION (stmt);
5222 warning (OPT_Wstrict_overflow,
5223 ("%Hassuming signed overflow does not occur when "
5224 "simplifying / or %% to >> or &"),
5229 if (val && integer_onep (val))
5232 tree op0 = TREE_OPERAND (rhs, 0);
5233 tree op1 = TREE_OPERAND (rhs, 1);
5235 if (rhs_code == TRUNC_DIV_EXPR)
5237 t = build_int_cst (NULL_TREE, tree_log2 (op1));
5238 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
5242 t = build_int_cst (TREE_TYPE (op1), 1);
5243 t = int_const_binop (MINUS_EXPR, op1, t, 0);
5244 t = fold_convert (TREE_TYPE (op0), t);
5245 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
5248 GIMPLE_STMT_OPERAND (stmt, 1) = t;
5253 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
5254 ABS_EXPR. If the operand is <= 0, then simplify the
5255 ABS_EXPR into a NEGATE_EXPR. */
5258 simplify_abs_using_ranges (tree stmt, tree rhs)
5261 tree op = TREE_OPERAND (rhs, 0);
5262 tree type = TREE_TYPE (op);
5263 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
5265 if (TYPE_UNSIGNED (type))
5267 val = integer_zero_node;
5273 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node, &sop);
5277 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node,
5282 if (integer_zerop (val))
5283 val = integer_one_node;
5284 else if (integer_onep (val))
5285 val = integer_zero_node;
5290 && (integer_onep (val) || integer_zerop (val)))
5294 if (sop && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
5298 if (!EXPR_HAS_LOCATION (stmt))
5299 locus = input_location;
5301 locus = EXPR_LOCATION (stmt);
5302 warning (OPT_Wstrict_overflow,
5303 ("%Hassuming signed overflow does not occur when "
5304 "simplifying abs (X) to X or -X"),
5308 if (integer_onep (val))
5309 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
5313 GIMPLE_STMT_OPERAND (stmt, 1) = t;
5319 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
5320 a known value range VR.
5322 If there is one and only one value which will satisfy the
5323 conditional, then return that value. Else return NULL. */
5326 test_for_singularity (enum tree_code cond_code, tree op0,
5327 tree op1, value_range_t *vr)
5332 /* Extract minimum/maximum values which satisfy the
5333 the conditional as it was written. */
5334 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
5336 /* This should not be negative infinity; there is no overflow
5338 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
5341 if (cond_code == LT_EXPR && !is_overflow_infinity (max))
5343 tree one = build_int_cst (TREE_TYPE (op0), 1);
5344 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
5347 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
5349 /* This should not be positive infinity; there is no overflow
5351 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
5354 if (cond_code == GT_EXPR && !is_overflow_infinity (min))
5356 tree one = build_int_cst (TREE_TYPE (op0), 1);
5357 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
5361 /* Now refine the minimum and maximum values using any
5362 value range information we have for op0. */
5365 if (compare_values (vr->min, min) == -1)
5369 if (compare_values (vr->max, max) == 1)
5374 /* If the new min/max values have converged to a single value,
5375 then there is only one value which can satisfy the condition,
5376 return that value. */
5377 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
5383 /* Simplify a conditional using a relational operator to an equality
5384 test if the range information indicates only one value can satisfy
5385 the original conditional. */
5388 simplify_cond_using_ranges (tree stmt)
5390 tree cond = COND_EXPR_COND (stmt);
5391 tree op0 = TREE_OPERAND (cond, 0);
5392 tree op1 = TREE_OPERAND (cond, 1);
5393 enum tree_code cond_code = TREE_CODE (cond);
5395 if (cond_code != NE_EXPR
5396 && cond_code != EQ_EXPR
5397 && TREE_CODE (op0) == SSA_NAME
5398 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
5399 && is_gimple_min_invariant (op1))
5401 value_range_t *vr = get_value_range (op0);
5403 /* If we have range information for OP0, then we might be
5404 able to simplify this conditional. */
5405 if (vr->type == VR_RANGE)
5407 tree new = test_for_singularity (cond_code, op0, op1, vr);
5413 fprintf (dump_file, "Simplified relational ");
5414 print_generic_expr (dump_file, cond, 0);
5415 fprintf (dump_file, " into ");
5418 COND_EXPR_COND (stmt)
5419 = build2 (EQ_EXPR, boolean_type_node, op0, new);
5424 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
5425 fprintf (dump_file, "\n");
5431 /* Try again after inverting the condition. We only deal
5432 with integral types here, so no need to worry about
5433 issues with inverting FP comparisons. */
5434 cond_code = invert_tree_comparison (cond_code, false);
5435 new = test_for_singularity (cond_code, op0, op1, vr);
5441 fprintf (dump_file, "Simplified relational ");
5442 print_generic_expr (dump_file, cond, 0);
5443 fprintf (dump_file, " into ");
5446 COND_EXPR_COND (stmt)
5447 = build2 (NE_EXPR, boolean_type_node, op0, new);
5452 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
5453 fprintf (dump_file, "\n");
5462 /* Simplify STMT using ranges if possible. */
5465 simplify_stmt_using_ranges (tree stmt)
5467 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
5469 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
5470 enum tree_code rhs_code = TREE_CODE (rhs);
5472 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
5473 and BIT_AND_EXPR respectively if the first operand is greater
5474 than zero and the second operand is an exact power of two. */
5475 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
5476 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
5477 && integer_pow2p (TREE_OPERAND (rhs, 1)))
5478 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
5480 /* Transform ABS (X) into X or -X as appropriate. */
5481 if (rhs_code == ABS_EXPR
5482 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
5483 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
5484 simplify_abs_using_ranges (stmt, rhs);
5486 else if (TREE_CODE (stmt) == COND_EXPR
5487 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
5489 simplify_cond_using_ranges (stmt);
5493 /* Stack of dest,src equivalency pairs that need to be restored after
5494 each attempt to thread a block's incoming edge to an outgoing edge.
5496 A NULL entry is used to mark the end of pairs which need to be
5498 static VEC(tree,heap) *stack;
5500 /* A trivial wrapper so that we can present the generic jump threading
5501 code with a simple API for simplifying statements. STMT is the
5502 statement we want to simplify, WITHIN_STMT provides the location
5503 for any overflow warnings. */
5506 simplify_stmt_for_jump_threading (tree stmt, tree within_stmt)
5508 /* We only use VRP information to simplify conditionals. This is
5509 overly conservative, but it's unclear if doing more would be
5510 worth the compile time cost. */
5511 if (TREE_CODE (stmt) != COND_EXPR)
5514 return vrp_evaluate_conditional (COND_EXPR_COND (stmt), within_stmt);
5517 /* Blocks which have more than one predecessor and more than
5518 one successor present jump threading opportunities. ie,
5519 when the block is reached from a specific predecessor, we
5520 may be able to determine which of the outgoing edges will
5521 be traversed. When this optimization applies, we are able
5522 to avoid conditionals at runtime and we may expose secondary
5523 optimization opportunities.
5525 This routine is effectively a driver for the generic jump
5526 threading code. It basically just presents the generic code
5527 with edges that may be suitable for jump threading.
5529 Unlike DOM, we do not iterate VRP if jump threading was successful.
5530 While iterating may expose new opportunities for VRP, it is expected
5531 those opportunities would be very limited and the compile time cost
5532 to expose those opportunities would be significant.
5534 As jump threading opportunities are discovered, they are registered
5535 for later realization. */
5538 identify_jump_threads (void)
5543 /* Ugh. When substituting values earlier in this pass we can
5544 wipe the dominance information. So rebuild the dominator
5545 information as we need it within the jump threading code. */
5546 calculate_dominance_info (CDI_DOMINATORS);
5548 /* We do not allow VRP information to be used for jump threading
5549 across a back edge in the CFG. Otherwise it becomes too
5550 difficult to avoid eliminating loop exit tests. Of course
5551 EDGE_DFS_BACK is not accurate at this time so we have to
5553 mark_dfs_back_edges ();
5555 /* Allocate our unwinder stack to unwind any temporary equivalences
5556 that might be recorded. */
5557 stack = VEC_alloc (tree, heap, 20);
5559 /* To avoid lots of silly node creation, we create a single
5560 conditional and just modify it in-place when attempting to
5562 dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL);
5563 dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL);
5565 /* Walk through all the blocks finding those which present a
5566 potential jump threading opportunity. We could set this up
5567 as a dominator walker and record data during the walk, but
5568 I doubt it's worth the effort for the classes of jump
5569 threading opportunities we are trying to identify at this
5570 point in compilation. */
5575 /* If the generic jump threading code does not find this block
5576 interesting, then there is nothing to do. */
5577 if (! potentially_threadable_block (bb))
5580 /* We only care about blocks ending in a COND_EXPR. While there
5581 may be some value in handling SWITCH_EXPR here, I doubt it's
5582 terribly important. */
5583 last = bsi_stmt (bsi_last (bb));
5584 if (TREE_CODE (last) != COND_EXPR)
5587 /* We're basically looking for any kind of conditional with
5588 integral type arguments. */
5589 cond = COND_EXPR_COND (last);
5590 if ((TREE_CODE (cond) == SSA_NAME
5591 && INTEGRAL_TYPE_P (TREE_TYPE (cond)))
5592 || (COMPARISON_CLASS_P (cond)
5593 && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
5594 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0)))
5595 && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME
5596 || is_gimple_min_invariant (TREE_OPERAND (cond, 1)))
5597 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
5602 /* We've got a block with multiple predecessors and multiple
5603 successors which also ends in a suitable conditional. For
5604 each predecessor, see if we can thread it to a specific
5606 FOR_EACH_EDGE (e, ei, bb->preds)
5608 /* Do not thread across back edges or abnormal edges
5610 if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
5613 thread_across_edge (dummy, e, true,
5615 simplify_stmt_for_jump_threading);
5620 /* We do not actually update the CFG or SSA graphs at this point as
5621 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
5622 handle ASSERT_EXPRs gracefully. */
5625 /* We identified all the jump threading opportunities earlier, but could
5626 not transform the CFG at that time. This routine transforms the
5627 CFG and arranges for the dominator tree to be rebuilt if necessary.
5629 Note the SSA graph update will occur during the normal TODO
5630 processing by the pass manager. */
5632 finalize_jump_threads (void)
5634 bool cfg_altered = false;
5635 cfg_altered = thread_through_all_blocks ();
5637 /* If we threaded jumps, then we need to recompute the dominance
5640 free_dominance_info (CDI_DOMINATORS);
5641 VEC_free (tree, heap, stack);
5645 /* Traverse all the blocks folding conditionals with known ranges. */
5651 prop_value_t *single_val_range;
5652 bool do_value_subst_p;
5656 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
5657 dump_all_value_ranges (dump_file);
5658 fprintf (dump_file, "\n");
5661 /* We may have ended with ranges that have exactly one value. Those
5662 values can be substituted as any other copy/const propagated
5663 value using substitute_and_fold. */
5664 single_val_range = XCNEWVEC (prop_value_t, num_ssa_names);
5666 do_value_subst_p = false;
5667 for (i = 0; i < num_ssa_names; i++)
5669 && vr_value[i]->type == VR_RANGE
5670 && vr_value[i]->min == vr_value[i]->max)
5672 single_val_range[i].value = vr_value[i]->min;
5673 do_value_subst_p = true;
5676 if (!do_value_subst_p)
5678 /* We found no single-valued ranges, don't waste time trying to
5679 do single value substitution in substitute_and_fold. */
5680 free (single_val_range);
5681 single_val_range = NULL;
5684 substitute_and_fold (single_val_range, true);
5686 if (warn_array_bounds)
5687 check_all_array_refs ();
5689 /* We must identify jump threading opportunities before we release
5690 the datastructures built by VRP. */
5691 identify_jump_threads ();
5693 /* Free allocated memory. */
5694 for (i = 0; i < num_ssa_names; i++)
5697 BITMAP_FREE (vr_value[i]->equiv);
5701 free (single_val_range);
5704 /* So that we can distinguish between VRP data being available
5705 and not available. */
5710 /* Main entry point to VRP (Value Range Propagation). This pass is
5711 loosely based on J. R. C. Patterson, ``Accurate Static Branch
5712 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
5713 Programming Language Design and Implementation, pp. 67-78, 1995.
5714 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
5716 This is essentially an SSA-CCP pass modified to deal with ranges
5717 instead of constants.
5719 While propagating ranges, we may find that two or more SSA name
5720 have equivalent, though distinct ranges. For instance,
5723 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
5725 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
5729 In the code above, pointer p_5 has range [q_2, q_2], but from the
5730 code we can also determine that p_5 cannot be NULL and, if q_2 had
5731 a non-varying range, p_5's range should also be compatible with it.
5733 These equivalences are created by two expressions: ASSERT_EXPR and
5734 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
5735 result of another assertion, then we can use the fact that p_5 and
5736 p_4 are equivalent when evaluating p_5's range.
5738 Together with value ranges, we also propagate these equivalences
5739 between names so that we can take advantage of information from
5740 multiple ranges when doing final replacement. Note that this
5741 equivalency relation is transitive but not symmetric.
5743 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
5744 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
5745 in contexts where that assertion does not hold (e.g., in line 6).
5747 TODO, the main difference between this pass and Patterson's is that
5748 we do not propagate edge probabilities. We only compute whether
5749 edges can be taken or not. That is, instead of having a spectrum
5750 of jump probabilities between 0 and 1, we only deal with 0, 1 and
5751 DON'T KNOW. In the future, it may be worthwhile to propagate
5752 probabilities to aid branch prediction. */
5757 insert_range_assertions ();
5759 loop_optimizer_init (LOOPS_NORMAL);
5764 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
5770 loop_optimizer_finalize ();
5773 /* ASSERT_EXPRs must be removed before finalizing jump threads
5774 as finalizing jump threads calls the CFG cleanup code which
5775 does not properly handle ASSERT_EXPRs. */
5776 remove_range_assertions ();
5778 /* If we exposed any new variables, go ahead and put them into
5779 SSA form now, before we handle jump threading. This simplifies
5780 interactions between rewriting of _DECL nodes into SSA form
5781 and rewriting SSA_NAME nodes into SSA form after block
5782 duplication and CFG manipulation. */
5783 update_ssa (TODO_update_ssa);
5785 finalize_jump_threads ();
5792 return flag_tree_vrp != 0;
5795 struct tree_opt_pass pass_vrp =
5798 gate_vrp, /* gate */
5799 execute_vrp, /* execute */
5802 0, /* static_pass_number */
5803 TV_TREE_VRP, /* tv_id */
5804 PROP_ssa | PROP_alias, /* properties_required */
5805 0, /* properties_provided */
5806 0, /* properties_destroyed */
5807 0, /* todo_flags_start */
5812 | TODO_update_ssa, /* todo_flags_finish */