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;
98 /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the
99 number of executable edges we saw the last time we visited the
101 static int *vr_phi_edge_counts;
104 /* Return whether TYPE should use an overflow infinity distinct from
105 TYPE_{MIN,MAX}_VALUE. We use an overflow infinity value to
106 represent a signed overflow during VRP computations. An infinity
107 is distinct from a half-range, which will go from some number to
108 TYPE_{MIN,MAX}_VALUE. */
111 needs_overflow_infinity (tree type)
113 return INTEGRAL_TYPE_P (type) && !TYPE_OVERFLOW_WRAPS (type);
116 /* Return whether TYPE can support our overflow infinity
117 representation: we use the TREE_OVERFLOW flag, which only exists
118 for constants. If TYPE doesn't support this, we don't optimize
119 cases which would require signed overflow--we drop them to
123 supports_overflow_infinity (tree type)
125 #ifdef ENABLE_CHECKING
126 gcc_assert (needs_overflow_infinity (type));
128 return (TYPE_MIN_VALUE (type) != NULL_TREE
129 && CONSTANT_CLASS_P (TYPE_MIN_VALUE (type))
130 && TYPE_MAX_VALUE (type) != NULL_TREE
131 && CONSTANT_CLASS_P (TYPE_MAX_VALUE (type)));
134 /* VAL is the maximum or minimum value of a type. Return a
135 corresponding overflow infinity. */
138 make_overflow_infinity (tree val)
140 #ifdef ENABLE_CHECKING
141 gcc_assert (val != NULL_TREE && CONSTANT_CLASS_P (val));
143 val = copy_node (val);
144 TREE_OVERFLOW (val) = 1;
148 /* Return a negative overflow infinity for TYPE. */
151 negative_overflow_infinity (tree type)
153 #ifdef ENABLE_CHECKING
154 gcc_assert (supports_overflow_infinity (type));
156 return make_overflow_infinity (TYPE_MIN_VALUE (type));
159 /* Return a positive overflow infinity for TYPE. */
162 positive_overflow_infinity (tree type)
164 #ifdef ENABLE_CHECKING
165 gcc_assert (supports_overflow_infinity (type));
167 return make_overflow_infinity (TYPE_MAX_VALUE (type));
170 /* Return whether VAL is a negative overflow infinity. */
173 is_negative_overflow_infinity (tree val)
175 return (needs_overflow_infinity (TREE_TYPE (val))
176 && CONSTANT_CLASS_P (val)
177 && TREE_OVERFLOW (val)
178 && operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0));
181 /* Return whether VAL is a positive overflow infinity. */
184 is_positive_overflow_infinity (tree val)
186 return (needs_overflow_infinity (TREE_TYPE (val))
187 && CONSTANT_CLASS_P (val)
188 && TREE_OVERFLOW (val)
189 && operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0));
192 /* Return whether VAL is a positive or negative overflow infinity. */
195 is_overflow_infinity (tree val)
197 return (needs_overflow_infinity (TREE_TYPE (val))
198 && CONSTANT_CLASS_P (val)
199 && TREE_OVERFLOW (val)
200 && (operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0)
201 || operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0)));
204 /* If VAL is now an overflow infinity, return VAL. Otherwise, return
205 the same value with TREE_OVERFLOW clear. This can be used to avoid
206 confusing a regular value with an overflow value. */
209 avoid_overflow_infinity (tree val)
211 if (!is_overflow_infinity (val))
214 if (operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0))
215 return TYPE_MAX_VALUE (TREE_TYPE (val));
218 #ifdef ENABLE_CHECKING
219 gcc_assert (operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0));
221 return TYPE_MIN_VALUE (TREE_TYPE (val));
226 /* Return whether VAL is equal to the maximum value of its type. This
227 will be true for a positive overflow infinity. We can't do a
228 simple equality comparison with TYPE_MAX_VALUE because C typedefs
229 and Ada subtypes can produce types whose TYPE_MAX_VALUE is not ==
230 to the integer constant with the same value in the type. */
233 vrp_val_is_max (tree val)
235 tree type_max = TYPE_MAX_VALUE (TREE_TYPE (val));
237 return (val == type_max
238 || (type_max != NULL_TREE
239 && operand_equal_p (val, type_max, 0)));
242 /* Return whether VAL is equal to the minimum value of its type. This
243 will be true for a negative overflow infinity. */
246 vrp_val_is_min (tree val)
248 tree type_min = TYPE_MIN_VALUE (TREE_TYPE (val));
250 return (val == type_min
251 || (type_min != NULL_TREE
252 && operand_equal_p (val, type_min, 0)));
256 /* Return true if ARG is marked with the nonnull attribute in the
257 current function signature. */
260 nonnull_arg_p (tree arg)
262 tree t, attrs, fntype;
263 unsigned HOST_WIDE_INT arg_num;
265 gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
267 /* The static chain decl is always non null. */
268 if (arg == cfun->static_chain_decl)
271 fntype = TREE_TYPE (current_function_decl);
272 attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype));
274 /* If "nonnull" wasn't specified, we know nothing about the argument. */
275 if (attrs == NULL_TREE)
278 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
279 if (TREE_VALUE (attrs) == NULL_TREE)
282 /* Get the position number for ARG in the function signature. */
283 for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl);
285 t = TREE_CHAIN (t), arg_num++)
291 gcc_assert (t == arg);
293 /* Now see if ARG_NUM is mentioned in the nonnull list. */
294 for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
296 if (compare_tree_int (TREE_VALUE (t), arg_num) == 0)
304 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
307 set_value_range (value_range_t *vr, enum value_range_type t, tree min,
308 tree max, bitmap equiv)
310 #if defined ENABLE_CHECKING
311 /* Check the validity of the range. */
312 if (t == VR_RANGE || t == VR_ANTI_RANGE)
316 gcc_assert (min && max);
318 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
319 gcc_assert (!vrp_val_is_min (min) || !vrp_val_is_max (max));
321 cmp = compare_values (min, max);
322 gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
324 if (needs_overflow_infinity (TREE_TYPE (min)))
325 gcc_assert (!is_overflow_infinity (min)
326 || !is_overflow_infinity (max));
329 if (t == VR_UNDEFINED || t == VR_VARYING)
330 gcc_assert (min == NULL_TREE && max == NULL_TREE);
332 if (t == VR_UNDEFINED || t == VR_VARYING)
333 gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
340 /* Since updating the equivalence set involves deep copying the
341 bitmaps, only do it if absolutely necessary. */
342 if (vr->equiv == NULL
344 vr->equiv = BITMAP_ALLOC (NULL);
346 if (equiv != vr->equiv)
348 if (equiv && !bitmap_empty_p (equiv))
349 bitmap_copy (vr->equiv, equiv);
351 bitmap_clear (vr->equiv);
356 /* Copy value range FROM into value range TO. */
359 copy_value_range (value_range_t *to, value_range_t *from)
361 set_value_range (to, from->type, from->min, from->max, from->equiv);
365 /* Set value range VR to VR_VARYING. */
368 set_value_range_to_varying (value_range_t *vr)
370 vr->type = VR_VARYING;
371 vr->min = vr->max = NULL_TREE;
373 bitmap_clear (vr->equiv);
376 /* Set value range VR to a single value. This function is only called
377 with values we get from statements, and exists to clear the
378 TREE_OVERFLOW flag so that we don't think we have an overflow
379 infinity when we shouldn't. */
382 set_value_range_to_value (value_range_t *vr, tree val, bitmap equiv)
384 gcc_assert (is_gimple_min_invariant (val));
385 val = avoid_overflow_infinity (val);
386 set_value_range (vr, VR_RANGE, val, val, equiv);
389 /* Set value range VR to a non-negative range of type TYPE.
390 OVERFLOW_INFINITY indicates whether to use an overflow infinity
391 rather than TYPE_MAX_VALUE; this should be true if we determine
392 that the range is nonnegative based on the assumption that signed
393 overflow does not occur. */
396 set_value_range_to_nonnegative (value_range_t *vr, tree type,
397 bool overflow_infinity)
401 if (overflow_infinity && !supports_overflow_infinity (type))
403 set_value_range_to_varying (vr);
407 zero = build_int_cst (type, 0);
408 set_value_range (vr, VR_RANGE, zero,
410 ? positive_overflow_infinity (type)
411 : TYPE_MAX_VALUE (type)),
415 /* Set value range VR to a non-NULL range of type TYPE. */
418 set_value_range_to_nonnull (value_range_t *vr, tree type)
420 tree zero = build_int_cst (type, 0);
421 set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
425 /* Set value range VR to a NULL range of type TYPE. */
428 set_value_range_to_null (value_range_t *vr, tree type)
430 set_value_range_to_value (vr, build_int_cst (type, 0), vr->equiv);
434 /* Set value range VR to a range of a truthvalue of type TYPE. */
437 set_value_range_to_truthvalue (value_range_t *vr, tree type)
439 if (TYPE_PRECISION (type) == 1)
440 set_value_range_to_varying (vr);
442 set_value_range (vr, VR_RANGE,
443 build_int_cst (type, 0), build_int_cst (type, 1),
448 /* Set value range VR to VR_UNDEFINED. */
451 set_value_range_to_undefined (value_range_t *vr)
453 vr->type = VR_UNDEFINED;
454 vr->min = vr->max = NULL_TREE;
456 bitmap_clear (vr->equiv);
460 /* Return value range information for VAR.
462 If we have no values ranges recorded (ie, VRP is not running), then
463 return NULL. Otherwise create an empty range if none existed for VAR. */
465 static value_range_t *
466 get_value_range (tree var)
470 unsigned ver = SSA_NAME_VERSION (var);
472 /* If we have no recorded ranges, then return NULL. */
480 /* Create a default value range. */
481 vr_value[ver] = vr = XCNEW (value_range_t);
483 /* Defer allocating the equivalence set. */
486 /* If VAR is a default definition, the variable can take any value
488 sym = SSA_NAME_VAR (var);
489 if (SSA_NAME_IS_DEFAULT_DEF (var))
491 /* Try to use the "nonnull" attribute to create ~[0, 0]
492 anti-ranges for pointers. Note that this is only valid with
493 default definitions of PARM_DECLs. */
494 if (TREE_CODE (sym) == PARM_DECL
495 && POINTER_TYPE_P (TREE_TYPE (sym))
496 && nonnull_arg_p (sym))
497 set_value_range_to_nonnull (vr, TREE_TYPE (sym));
499 set_value_range_to_varying (vr);
505 /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */
508 vrp_operand_equal_p (tree val1, tree val2)
512 if (!val1 || !val2 || !operand_equal_p (val1, val2, 0))
514 if (is_overflow_infinity (val1))
515 return is_overflow_infinity (val2);
519 /* Return true, if the bitmaps B1 and B2 are equal. */
522 vrp_bitmap_equal_p (bitmap b1, bitmap b2)
526 && bitmap_equal_p (b1, b2)));
529 /* Update the value range and equivalence set for variable VAR to
530 NEW_VR. Return true if NEW_VR is different from VAR's previous
533 NOTE: This function assumes that NEW_VR is a temporary value range
534 object created for the sole purpose of updating VAR's range. The
535 storage used by the equivalence set from NEW_VR will be freed by
536 this function. Do not call update_value_range when NEW_VR
537 is the range object associated with another SSA name. */
540 update_value_range (tree var, value_range_t *new_vr)
542 value_range_t *old_vr;
545 /* Update the value range, if necessary. */
546 old_vr = get_value_range (var);
547 is_new = old_vr->type != new_vr->type
548 || !vrp_operand_equal_p (old_vr->min, new_vr->min)
549 || !vrp_operand_equal_p (old_vr->max, new_vr->max)
550 || !vrp_bitmap_equal_p (old_vr->equiv, new_vr->equiv);
553 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
556 BITMAP_FREE (new_vr->equiv);
562 /* Add VAR and VAR's equivalence set to EQUIV. This is the central
563 point where equivalence processing can be turned on/off. */
566 add_equivalence (bitmap *equiv, tree var)
568 unsigned ver = SSA_NAME_VERSION (var);
569 value_range_t *vr = vr_value[ver];
572 *equiv = BITMAP_ALLOC (NULL);
573 bitmap_set_bit (*equiv, ver);
575 bitmap_ior_into (*equiv, vr->equiv);
579 /* Return true if VR is ~[0, 0]. */
582 range_is_nonnull (value_range_t *vr)
584 return vr->type == VR_ANTI_RANGE
585 && integer_zerop (vr->min)
586 && integer_zerop (vr->max);
590 /* Return true if VR is [0, 0]. */
593 range_is_null (value_range_t *vr)
595 return vr->type == VR_RANGE
596 && integer_zerop (vr->min)
597 && integer_zerop (vr->max);
601 /* Return true if value range VR involves at least one symbol. */
604 symbolic_range_p (value_range_t *vr)
606 return (!is_gimple_min_invariant (vr->min)
607 || !is_gimple_min_invariant (vr->max));
610 /* Return true if value range VR uses an overflow infinity. */
613 overflow_infinity_range_p (value_range_t *vr)
615 return (vr->type == VR_RANGE
616 && (is_overflow_infinity (vr->min)
617 || is_overflow_infinity (vr->max)));
620 /* Return false if we can not make a valid comparison based on VR;
621 this will be the case if it uses an overflow infinity and overflow
622 is not undefined (i.e., -fno-strict-overflow is in effect).
623 Otherwise return true, and set *STRICT_OVERFLOW_P to true if VR
624 uses an overflow infinity. */
627 usable_range_p (value_range_t *vr, bool *strict_overflow_p)
629 gcc_assert (vr->type == VR_RANGE);
630 if (is_overflow_infinity (vr->min))
632 *strict_overflow_p = true;
633 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->min)))
636 if (is_overflow_infinity (vr->max))
638 *strict_overflow_p = true;
639 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->max)))
646 /* Like tree_expr_nonnegative_warnv_p, but this function uses value
647 ranges obtained so far. */
650 vrp_expr_computes_nonnegative (tree expr, bool *strict_overflow_p)
652 return tree_expr_nonnegative_warnv_p (expr, strict_overflow_p);
655 /* Like tree_expr_nonzero_warnv_p, but this function uses value ranges
659 vrp_expr_computes_nonzero (tree expr, bool *strict_overflow_p)
661 if (tree_expr_nonzero_warnv_p (expr, strict_overflow_p))
664 /* If we have an expression of the form &X->a, then the expression
665 is nonnull if X is nonnull. */
666 if (TREE_CODE (expr) == ADDR_EXPR)
668 tree base = get_base_address (TREE_OPERAND (expr, 0));
670 if (base != NULL_TREE
671 && TREE_CODE (base) == INDIRECT_REF
672 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
674 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
675 if (range_is_nonnull (vr))
683 /* Returns true if EXPR is a valid value (as expected by compare_values) --
684 a gimple invariant, or SSA_NAME +- CST. */
687 valid_value_p (tree expr)
689 if (TREE_CODE (expr) == SSA_NAME)
692 if (TREE_CODE (expr) == PLUS_EXPR
693 || TREE_CODE (expr) == MINUS_EXPR)
694 return (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME
695 && TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST);
697 return is_gimple_min_invariant (expr);
703 -2 if those are incomparable. */
705 operand_less_p (tree val, tree val2)
707 /* LT is folded faster than GE and others. Inline the common case. */
708 if (TREE_CODE (val) == INTEGER_CST && TREE_CODE (val2) == INTEGER_CST)
710 if (TYPE_UNSIGNED (TREE_TYPE (val)))
711 return INT_CST_LT_UNSIGNED (val, val2);
714 if (INT_CST_LT (val, val2))
722 fold_defer_overflow_warnings ();
724 tcmp = fold_binary_to_constant (LT_EXPR, boolean_type_node, val, val2);
726 fold_undefer_and_ignore_overflow_warnings ();
731 if (!integer_zerop (tcmp))
735 /* val >= val2, not considering overflow infinity. */
736 if (is_negative_overflow_infinity (val))
737 return is_negative_overflow_infinity (val2) ? 0 : 1;
738 else if (is_positive_overflow_infinity (val2))
739 return is_positive_overflow_infinity (val) ? 0 : 1;
744 /* Compare two values VAL1 and VAL2. Return
746 -2 if VAL1 and VAL2 cannot be compared at compile-time,
749 +1 if VAL1 > VAL2, and
752 This is similar to tree_int_cst_compare but supports pointer values
753 and values that cannot be compared at compile time.
755 If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to
756 true if the return value is only valid if we assume that signed
757 overflow is undefined. */
760 compare_values_warnv (tree val1, tree val2, bool *strict_overflow_p)
765 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
767 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
768 == POINTER_TYPE_P (TREE_TYPE (val2)));
770 if ((TREE_CODE (val1) == SSA_NAME
771 || TREE_CODE (val1) == PLUS_EXPR
772 || TREE_CODE (val1) == MINUS_EXPR)
773 && (TREE_CODE (val2) == SSA_NAME
774 || TREE_CODE (val2) == PLUS_EXPR
775 || TREE_CODE (val2) == MINUS_EXPR))
778 enum tree_code code1, code2;
780 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
781 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
782 same name, return -2. */
783 if (TREE_CODE (val1) == SSA_NAME)
791 code1 = TREE_CODE (val1);
792 n1 = TREE_OPERAND (val1, 0);
793 c1 = TREE_OPERAND (val1, 1);
794 if (tree_int_cst_sgn (c1) == -1)
796 if (is_negative_overflow_infinity (c1))
798 c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1);
801 code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
805 if (TREE_CODE (val2) == SSA_NAME)
813 code2 = TREE_CODE (val2);
814 n2 = TREE_OPERAND (val2, 0);
815 c2 = TREE_OPERAND (val2, 1);
816 if (tree_int_cst_sgn (c2) == -1)
818 if (is_negative_overflow_infinity (c2))
820 c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2);
823 code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
827 /* Both values must use the same name. */
831 if (code1 == SSA_NAME
832 && code2 == SSA_NAME)
836 /* If overflow is defined we cannot simplify more. */
837 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1)))
840 if (strict_overflow_p != NULL
841 && (code1 == SSA_NAME || !TREE_NO_WARNING (val1))
842 && (code2 == SSA_NAME || !TREE_NO_WARNING (val2)))
843 *strict_overflow_p = true;
845 if (code1 == SSA_NAME)
847 if (code2 == PLUS_EXPR)
848 /* NAME < NAME + CST */
850 else if (code2 == MINUS_EXPR)
851 /* NAME > NAME - CST */
854 else if (code1 == PLUS_EXPR)
856 if (code2 == SSA_NAME)
857 /* NAME + CST > NAME */
859 else if (code2 == PLUS_EXPR)
860 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
861 return compare_values_warnv (c1, c2, strict_overflow_p);
862 else if (code2 == MINUS_EXPR)
863 /* NAME + CST1 > NAME - CST2 */
866 else if (code1 == MINUS_EXPR)
868 if (code2 == SSA_NAME)
869 /* NAME - CST < NAME */
871 else if (code2 == PLUS_EXPR)
872 /* NAME - CST1 < NAME + CST2 */
874 else if (code2 == MINUS_EXPR)
875 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
876 C1 and C2 are swapped in the call to compare_values. */
877 return compare_values_warnv (c2, c1, strict_overflow_p);
883 /* We cannot compare non-constants. */
884 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
887 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
889 /* We cannot compare overflowed values, except for overflow
891 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
893 if (strict_overflow_p != NULL)
894 *strict_overflow_p = true;
895 if (is_negative_overflow_infinity (val1))
896 return is_negative_overflow_infinity (val2) ? 0 : -1;
897 else if (is_negative_overflow_infinity (val2))
899 else if (is_positive_overflow_infinity (val1))
900 return is_positive_overflow_infinity (val2) ? 0 : 1;
901 else if (is_positive_overflow_infinity (val2))
906 return tree_int_cst_compare (val1, val2);
912 /* First see if VAL1 and VAL2 are not the same. */
913 if (val1 == val2 || operand_equal_p (val1, val2, 0))
916 /* If VAL1 is a lower address than VAL2, return -1. */
917 if (operand_less_p (val1, val2) == 1)
920 /* If VAL1 is a higher address than VAL2, return +1. */
921 if (operand_less_p (val2, val1) == 1)
924 /* If VAL1 is different than VAL2, return +2.
925 For integer constants we either have already returned -1 or 1
926 or they are equivalent. We still might succeed in proving
927 something about non-trivial operands. */
928 if (TREE_CODE (val1) != INTEGER_CST
929 || TREE_CODE (val2) != INTEGER_CST)
931 t = fold_binary_to_constant (NE_EXPR, boolean_type_node, val1, val2);
932 if (t && tree_expr_nonzero_p (t))
940 /* Compare values like compare_values_warnv, but treat comparisons of
941 nonconstants which rely on undefined overflow as incomparable. */
944 compare_values (tree val1, tree val2)
950 ret = compare_values_warnv (val1, val2, &sop);
952 && (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2)))
958 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
959 0 if VAL is not inside VR,
960 -2 if we cannot tell either way.
962 FIXME, the current semantics of this functions are a bit quirky
963 when taken in the context of VRP. In here we do not care
964 about VR's type. If VR is the anti-range ~[3, 5] the call
965 value_inside_range (4, VR) will return 1.
967 This is counter-intuitive in a strict sense, but the callers
968 currently expect this. They are calling the function
969 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
970 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
973 This also applies to value_ranges_intersect_p and
974 range_includes_zero_p. The semantics of VR_RANGE and
975 VR_ANTI_RANGE should be encoded here, but that also means
976 adapting the users of these functions to the new semantics.
978 Benchmark compile/20001226-1.c compilation time after changing this
982 value_inside_range (tree val, value_range_t * vr)
986 cmp1 = operand_less_p (val, vr->min);
992 cmp2 = operand_less_p (vr->max, val);
1000 /* Return true if value ranges VR0 and VR1 have a non-empty
1003 Benchmark compile/20001226-1.c compilation time after changing this
1008 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
1010 /* The value ranges do not intersect if the maximum of the first range is
1011 less than the minimum of the second range or vice versa.
1012 When those relations are unknown, we can't do any better. */
1013 if (operand_less_p (vr0->max, vr1->min) != 0)
1015 if (operand_less_p (vr1->max, vr0->min) != 0)
1021 /* Return true if VR includes the value zero, false otherwise. FIXME,
1022 currently this will return false for an anti-range like ~[-4, 3].
1023 This will be wrong when the semantics of value_inside_range are
1024 modified (currently the users of this function expect these
1028 range_includes_zero_p (value_range_t *vr)
1032 gcc_assert (vr->type != VR_UNDEFINED
1033 && vr->type != VR_VARYING
1034 && !symbolic_range_p (vr));
1036 zero = build_int_cst (TREE_TYPE (vr->min), 0);
1037 return (value_inside_range (zero, vr) == 1);
1040 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
1041 false otherwise or if no value range information is available. */
1044 ssa_name_nonnegative_p (tree t)
1046 value_range_t *vr = get_value_range (t);
1051 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
1052 which would return a useful value should be encoded as a VR_RANGE. */
1053 if (vr->type == VR_RANGE)
1055 int result = compare_values (vr->min, integer_zero_node);
1057 return (result == 0 || result == 1);
1062 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
1063 false otherwise or if no value range information is available. */
1066 ssa_name_nonzero_p (tree t)
1068 value_range_t *vr = get_value_range (t);
1073 /* A VR_RANGE which does not include zero is a nonzero value. */
1074 if (vr->type == VR_RANGE && !symbolic_range_p (vr))
1075 return ! range_includes_zero_p (vr);
1077 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
1078 if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr))
1079 return range_includes_zero_p (vr);
1085 /* Extract value range information from an ASSERT_EXPR EXPR and store
1089 extract_range_from_assert (value_range_t *vr_p, tree expr)
1091 tree var, cond, limit, min, max, type;
1092 value_range_t *var_vr, *limit_vr;
1093 enum tree_code cond_code;
1095 var = ASSERT_EXPR_VAR (expr);
1096 cond = ASSERT_EXPR_COND (expr);
1098 gcc_assert (COMPARISON_CLASS_P (cond));
1100 /* Find VAR in the ASSERT_EXPR conditional. */
1101 if (var == TREE_OPERAND (cond, 0))
1103 /* If the predicate is of the form VAR COMP LIMIT, then we just
1104 take LIMIT from the RHS and use the same comparison code. */
1105 limit = TREE_OPERAND (cond, 1);
1106 cond_code = TREE_CODE (cond);
1110 /* If the predicate is of the form LIMIT COMP VAR, then we need
1111 to flip around the comparison code to create the proper range
1113 limit = TREE_OPERAND (cond, 0);
1114 cond_code = swap_tree_comparison (TREE_CODE (cond));
1117 limit = avoid_overflow_infinity (limit);
1119 type = TREE_TYPE (limit);
1120 gcc_assert (limit != var);
1122 /* For pointer arithmetic, we only keep track of pointer equality
1124 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
1126 set_value_range_to_varying (vr_p);
1130 /* If LIMIT is another SSA name and LIMIT has a range of its own,
1131 try to use LIMIT's range to avoid creating symbolic ranges
1133 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
1135 /* LIMIT's range is only interesting if it has any useful information. */
1137 && (limit_vr->type == VR_UNDEFINED
1138 || limit_vr->type == VR_VARYING
1139 || symbolic_range_p (limit_vr)))
1142 /* Initially, the new range has the same set of equivalences of
1143 VAR's range. This will be revised before returning the final
1144 value. Since assertions may be chained via mutually exclusive
1145 predicates, we will need to trim the set of equivalences before
1147 gcc_assert (vr_p->equiv == NULL);
1148 add_equivalence (&vr_p->equiv, var);
1150 /* Extract a new range based on the asserted comparison for VAR and
1151 LIMIT's value range. Notice that if LIMIT has an anti-range, we
1152 will only use it for equality comparisons (EQ_EXPR). For any
1153 other kind of assertion, we cannot derive a range from LIMIT's
1154 anti-range that can be used to describe the new range. For
1155 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
1156 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
1157 no single range for x_2 that could describe LE_EXPR, so we might
1158 as well build the range [b_4, +INF] for it. */
1159 if (cond_code == EQ_EXPR)
1161 enum value_range_type range_type;
1165 range_type = limit_vr->type;
1166 min = limit_vr->min;
1167 max = limit_vr->max;
1171 range_type = VR_RANGE;
1176 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
1178 /* When asserting the equality VAR == LIMIT and LIMIT is another
1179 SSA name, the new range will also inherit the equivalence set
1181 if (TREE_CODE (limit) == SSA_NAME)
1182 add_equivalence (&vr_p->equiv, limit);
1184 else if (cond_code == NE_EXPR)
1186 /* As described above, when LIMIT's range is an anti-range and
1187 this assertion is an inequality (NE_EXPR), then we cannot
1188 derive anything from the anti-range. For instance, if
1189 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
1190 not imply that VAR's range is [0, 0]. So, in the case of
1191 anti-ranges, we just assert the inequality using LIMIT and
1194 If LIMIT_VR is a range, we can only use it to build a new
1195 anti-range if LIMIT_VR is a single-valued range. For
1196 instance, if LIMIT_VR is [0, 1], the predicate
1197 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
1198 Rather, it means that for value 0 VAR should be ~[0, 0]
1199 and for value 1, VAR should be ~[1, 1]. We cannot
1200 represent these ranges.
1202 The only situation in which we can build a valid
1203 anti-range is when LIMIT_VR is a single-valued range
1204 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
1205 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
1207 && limit_vr->type == VR_RANGE
1208 && compare_values (limit_vr->min, limit_vr->max) == 0)
1210 min = limit_vr->min;
1211 max = limit_vr->max;
1215 /* In any other case, we cannot use LIMIT's range to build a
1216 valid anti-range. */
1220 /* If MIN and MAX cover the whole range for their type, then
1221 just use the original LIMIT. */
1222 if (INTEGRAL_TYPE_P (type)
1223 && vrp_val_is_min (min)
1224 && vrp_val_is_max (max))
1227 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
1229 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
1231 min = TYPE_MIN_VALUE (type);
1233 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
1237 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1238 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
1240 max = limit_vr->max;
1243 /* If the maximum value forces us to be out of bounds, simply punt.
1244 It would be pointless to try and do anything more since this
1245 all should be optimized away above us. */
1246 if ((cond_code == LT_EXPR
1247 && compare_values (max, min) == 0)
1248 || is_overflow_infinity (max))
1249 set_value_range_to_varying (vr_p);
1252 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
1253 if (cond_code == LT_EXPR)
1255 tree one = build_int_cst (type, 1);
1256 max = fold_build2 (MINUS_EXPR, type, max, one);
1258 TREE_NO_WARNING (max) = 1;
1261 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1264 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
1266 max = TYPE_MAX_VALUE (type);
1268 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
1272 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1273 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
1275 min = limit_vr->min;
1278 /* If the minimum value forces us to be out of bounds, simply punt.
1279 It would be pointless to try and do anything more since this
1280 all should be optimized away above us. */
1281 if ((cond_code == GT_EXPR
1282 && compare_values (min, max) == 0)
1283 || is_overflow_infinity (min))
1284 set_value_range_to_varying (vr_p);
1287 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
1288 if (cond_code == GT_EXPR)
1290 tree one = build_int_cst (type, 1);
1291 min = fold_build2 (PLUS_EXPR, type, min, one);
1293 TREE_NO_WARNING (min) = 1;
1296 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1302 /* If VAR already had a known range, it may happen that the new
1303 range we have computed and VAR's range are not compatible. For
1307 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
1309 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
1311 While the above comes from a faulty program, it will cause an ICE
1312 later because p_8 and p_6 will have incompatible ranges and at
1313 the same time will be considered equivalent. A similar situation
1317 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
1319 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
1321 Again i_6 and i_7 will have incompatible ranges. It would be
1322 pointless to try and do anything with i_7's range because
1323 anything dominated by 'if (i_5 < 5)' will be optimized away.
1324 Note, due to the wa in which simulation proceeds, the statement
1325 i_7 = ASSERT_EXPR <...> we would never be visited because the
1326 conditional 'if (i_5 < 5)' always evaluates to false. However,
1327 this extra check does not hurt and may protect against future
1328 changes to VRP that may get into a situation similar to the
1329 NULL pointer dereference example.
1331 Note that these compatibility tests are only needed when dealing
1332 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1333 are both anti-ranges, they will always be compatible, because two
1334 anti-ranges will always have a non-empty intersection. */
1336 var_vr = get_value_range (var);
1338 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1339 ranges or anti-ranges. */
1340 if (vr_p->type == VR_VARYING
1341 || vr_p->type == VR_UNDEFINED
1342 || var_vr->type == VR_VARYING
1343 || var_vr->type == VR_UNDEFINED
1344 || symbolic_range_p (vr_p)
1345 || symbolic_range_p (var_vr))
1348 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
1350 /* If the two ranges have a non-empty intersection, we can
1351 refine the resulting range. Since the assert expression
1352 creates an equivalency and at the same time it asserts a
1353 predicate, we can take the intersection of the two ranges to
1354 get better precision. */
1355 if (value_ranges_intersect_p (var_vr, vr_p))
1357 /* Use the larger of the two minimums. */
1358 if (compare_values (vr_p->min, var_vr->min) == -1)
1363 /* Use the smaller of the two maximums. */
1364 if (compare_values (vr_p->max, var_vr->max) == 1)
1369 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
1373 /* The two ranges do not intersect, set the new range to
1374 VARYING, because we will not be able to do anything
1375 meaningful with it. */
1376 set_value_range_to_varying (vr_p);
1379 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
1380 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
1382 /* A range and an anti-range will cancel each other only if
1383 their ends are the same. For instance, in the example above,
1384 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1385 so VR_P should be set to VR_VARYING. */
1386 if (compare_values (var_vr->min, vr_p->min) == 0
1387 && compare_values (var_vr->max, vr_p->max) == 0)
1388 set_value_range_to_varying (vr_p);
1391 tree min, max, anti_min, anti_max, real_min, real_max;
1394 /* We want to compute the logical AND of the two ranges;
1395 there are three cases to consider.
1398 1. The VR_ANTI_RANGE range is completely within the
1399 VR_RANGE and the endpoints of the ranges are
1400 different. In that case the resulting range
1401 should be whichever range is more precise.
1402 Typically that will be the VR_RANGE.
1404 2. The VR_ANTI_RANGE is completely disjoint from
1405 the VR_RANGE. In this case the resulting range
1406 should be the VR_RANGE.
1408 3. There is some overlap between the VR_ANTI_RANGE
1411 3a. If the high limit of the VR_ANTI_RANGE resides
1412 within the VR_RANGE, then the result is a new
1413 VR_RANGE starting at the high limit of the
1414 the VR_ANTI_RANGE + 1 and extending to the
1415 high limit of the original VR_RANGE.
1417 3b. If the low limit of the VR_ANTI_RANGE resides
1418 within the VR_RANGE, then the result is a new
1419 VR_RANGE starting at the low limit of the original
1420 VR_RANGE and extending to the low limit of the
1421 VR_ANTI_RANGE - 1. */
1422 if (vr_p->type == VR_ANTI_RANGE)
1424 anti_min = vr_p->min;
1425 anti_max = vr_p->max;
1426 real_min = var_vr->min;
1427 real_max = var_vr->max;
1431 anti_min = var_vr->min;
1432 anti_max = var_vr->max;
1433 real_min = vr_p->min;
1434 real_max = vr_p->max;
1438 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1439 not including any endpoints. */
1440 if (compare_values (anti_max, real_max) == -1
1441 && compare_values (anti_min, real_min) == 1)
1443 set_value_range (vr_p, VR_RANGE, real_min,
1444 real_max, vr_p->equiv);
1446 /* Case 2, VR_ANTI_RANGE completely disjoint from
1448 else if (compare_values (anti_min, real_max) == 1
1449 || compare_values (anti_max, real_min) == -1)
1451 set_value_range (vr_p, VR_RANGE, real_min,
1452 real_max, vr_p->equiv);
1454 /* Case 3a, the anti-range extends into the low
1455 part of the real range. Thus creating a new
1456 low for the real range. */
1457 else if (((cmp = compare_values (anti_max, real_min)) == 1
1459 && compare_values (anti_max, real_max) == -1)
1461 gcc_assert (!is_positive_overflow_infinity (anti_max));
1462 if (needs_overflow_infinity (TREE_TYPE (anti_max))
1463 && vrp_val_is_max (anti_max))
1465 if (!supports_overflow_infinity (TREE_TYPE (var_vr->min)))
1467 set_value_range_to_varying (vr_p);
1470 min = positive_overflow_infinity (TREE_TYPE (var_vr->min));
1473 min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min),
1475 build_int_cst (TREE_TYPE (var_vr->min), 1));
1477 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1479 /* Case 3b, the anti-range extends into the high
1480 part of the real range. Thus creating a new
1481 higher for the real range. */
1482 else if (compare_values (anti_min, real_min) == 1
1483 && ((cmp = compare_values (anti_min, real_max)) == -1
1486 gcc_assert (!is_negative_overflow_infinity (anti_min));
1487 if (needs_overflow_infinity (TREE_TYPE (anti_min))
1488 && vrp_val_is_min (anti_min))
1490 if (!supports_overflow_infinity (TREE_TYPE (var_vr->min)))
1492 set_value_range_to_varying (vr_p);
1495 max = negative_overflow_infinity (TREE_TYPE (var_vr->min));
1498 max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min),
1500 build_int_cst (TREE_TYPE (var_vr->min), 1));
1502 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1509 /* Extract range information from SSA name VAR and store it in VR. If
1510 VAR has an interesting range, use it. Otherwise, create the
1511 range [VAR, VAR] and return it. This is useful in situations where
1512 we may have conditionals testing values of VARYING names. For
1519 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1523 extract_range_from_ssa_name (value_range_t *vr, tree var)
1525 value_range_t *var_vr = get_value_range (var);
1527 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
1528 copy_value_range (vr, var_vr);
1530 set_value_range (vr, VR_RANGE, var, var, NULL);
1532 add_equivalence (&vr->equiv, var);
1536 /* Wrapper around int_const_binop. If the operation overflows and we
1537 are not using wrapping arithmetic, then adjust the result to be
1538 -INF or +INF depending on CODE, VAL1 and VAL2. This can return
1539 NULL_TREE if we need to use an overflow infinity representation but
1540 the type does not support it. */
1543 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
1547 res = int_const_binop (code, val1, val2, 0);
1549 /* If we are not using wrapping arithmetic, operate symbolically
1550 on -INF and +INF. */
1551 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1)))
1553 int checkz = compare_values (res, val1);
1554 bool overflow = false;
1556 /* Ensure that res = val1 [+*] val2 >= val1
1557 or that res = val1 - val2 <= val1. */
1558 if ((code == PLUS_EXPR
1559 && !(checkz == 1 || checkz == 0))
1560 || (code == MINUS_EXPR
1561 && !(checkz == 0 || checkz == -1)))
1565 /* Checking for multiplication overflow is done by dividing the
1566 output of the multiplication by the first input of the
1567 multiplication. If the result of that division operation is
1568 not equal to the second input of the multiplication, then the
1569 multiplication overflowed. */
1570 else if (code == MULT_EXPR && !integer_zerop (val1))
1572 tree tmp = int_const_binop (TRUNC_DIV_EXPR,
1575 int check = compare_values (tmp, val2);
1583 res = copy_node (res);
1584 TREE_OVERFLOW (res) = 1;
1588 else if ((TREE_OVERFLOW (res)
1589 && !TREE_OVERFLOW (val1)
1590 && !TREE_OVERFLOW (val2))
1591 || is_overflow_infinity (val1)
1592 || is_overflow_infinity (val2))
1594 /* If the operation overflowed but neither VAL1 nor VAL2 are
1595 overflown, return -INF or +INF depending on the operation
1596 and the combination of signs of the operands. */
1597 int sgn1 = tree_int_cst_sgn (val1);
1598 int sgn2 = tree_int_cst_sgn (val2);
1600 if (needs_overflow_infinity (TREE_TYPE (res))
1601 && !supports_overflow_infinity (TREE_TYPE (res)))
1604 /* We have to punt on adding infinities of different signs,
1605 since we can't tell what the sign of the result should be.
1606 Likewise for subtracting infinities of the same sign. */
1607 if (((code == PLUS_EXPR && sgn1 != sgn2)
1608 || (code == MINUS_EXPR && sgn1 == sgn2))
1609 && is_overflow_infinity (val1)
1610 && is_overflow_infinity (val2))
1613 /* Don't try to handle division or shifting of infinities. */
1614 if ((code == TRUNC_DIV_EXPR
1615 || code == FLOOR_DIV_EXPR
1616 || code == CEIL_DIV_EXPR
1617 || code == EXACT_DIV_EXPR
1618 || code == ROUND_DIV_EXPR
1619 || code == RSHIFT_EXPR)
1620 && (is_overflow_infinity (val1)
1621 || is_overflow_infinity (val2)))
1624 /* Notice that we only need to handle the restricted set of
1625 operations handled by extract_range_from_binary_expr.
1626 Among them, only multiplication, addition and subtraction
1627 can yield overflow without overflown operands because we
1628 are working with integral types only... except in the
1629 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1630 for division too. */
1632 /* For multiplication, the sign of the overflow is given
1633 by the comparison of the signs of the operands. */
1634 if ((code == MULT_EXPR && sgn1 == sgn2)
1635 /* For addition, the operands must be of the same sign
1636 to yield an overflow. Its sign is therefore that
1637 of one of the operands, for example the first. For
1638 infinite operands X + -INF is negative, not positive. */
1639 || (code == PLUS_EXPR
1641 ? !is_negative_overflow_infinity (val2)
1642 : is_positive_overflow_infinity (val2)))
1643 /* For subtraction, non-infinite operands must be of
1644 different signs to yield an overflow. Its sign is
1645 therefore that of the first operand or the opposite of
1646 that of the second operand. A first operand of 0 counts
1647 as positive here, for the corner case 0 - (-INF), which
1648 overflows, but must yield +INF. For infinite operands 0
1649 - INF is negative, not positive. */
1650 || (code == MINUS_EXPR
1652 ? !is_positive_overflow_infinity (val2)
1653 : is_negative_overflow_infinity (val2)))
1654 /* We only get in here with positive shift count, so the
1655 overflow direction is the same as the sign of val1.
1656 Actually rshift does not overflow at all, but we only
1657 handle the case of shifting overflowed -INF and +INF. */
1658 || (code == RSHIFT_EXPR
1660 /* For division, the only case is -INF / -1 = +INF. */
1661 || code == TRUNC_DIV_EXPR
1662 || code == FLOOR_DIV_EXPR
1663 || code == CEIL_DIV_EXPR
1664 || code == EXACT_DIV_EXPR
1665 || code == ROUND_DIV_EXPR)
1666 return (needs_overflow_infinity (TREE_TYPE (res))
1667 ? positive_overflow_infinity (TREE_TYPE (res))
1668 : TYPE_MAX_VALUE (TREE_TYPE (res)));
1670 return (needs_overflow_infinity (TREE_TYPE (res))
1671 ? negative_overflow_infinity (TREE_TYPE (res))
1672 : TYPE_MIN_VALUE (TREE_TYPE (res)));
1679 /* Extract range information from a binary expression EXPR based on
1680 the ranges of each of its operands and the expression code. */
1683 extract_range_from_binary_expr (value_range_t *vr, tree expr)
1685 enum tree_code code = TREE_CODE (expr);
1686 enum value_range_type type;
1687 tree op0, op1, min, max;
1689 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1690 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1692 /* Not all binary expressions can be applied to ranges in a
1693 meaningful way. Handle only arithmetic operations. */
1694 if (code != PLUS_EXPR
1695 && code != MINUS_EXPR
1696 && code != MULT_EXPR
1697 && code != TRUNC_DIV_EXPR
1698 && code != FLOOR_DIV_EXPR
1699 && code != CEIL_DIV_EXPR
1700 && code != EXACT_DIV_EXPR
1701 && code != ROUND_DIV_EXPR
1702 && code != RSHIFT_EXPR
1705 && code != BIT_AND_EXPR
1706 && code != TRUTH_ANDIF_EXPR
1707 && code != TRUTH_ORIF_EXPR
1708 && code != TRUTH_AND_EXPR
1709 && code != TRUTH_OR_EXPR)
1711 set_value_range_to_varying (vr);
1715 /* Get value ranges for each operand. For constant operands, create
1716 a new value range with the operand to simplify processing. */
1717 op0 = TREE_OPERAND (expr, 0);
1718 if (TREE_CODE (op0) == SSA_NAME)
1719 vr0 = *(get_value_range (op0));
1720 else if (is_gimple_min_invariant (op0))
1721 set_value_range_to_value (&vr0, op0, NULL);
1723 set_value_range_to_varying (&vr0);
1725 op1 = TREE_OPERAND (expr, 1);
1726 if (TREE_CODE (op1) == SSA_NAME)
1727 vr1 = *(get_value_range (op1));
1728 else if (is_gimple_min_invariant (op1))
1729 set_value_range_to_value (&vr1, op1, NULL);
1731 set_value_range_to_varying (&vr1);
1733 /* If either range is UNDEFINED, so is the result. */
1734 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1736 set_value_range_to_undefined (vr);
1740 /* The type of the resulting value range defaults to VR0.TYPE. */
1743 /* Refuse to operate on VARYING ranges, ranges of different kinds
1744 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1745 because we may be able to derive a useful range even if one of
1746 the operands is VR_VARYING or symbolic range. TODO, we may be
1747 able to derive anti-ranges in some cases. */
1748 if (code != BIT_AND_EXPR
1749 && code != TRUTH_AND_EXPR
1750 && code != TRUTH_OR_EXPR
1751 && (vr0.type == VR_VARYING
1752 || vr1.type == VR_VARYING
1753 || vr0.type != vr1.type
1754 || symbolic_range_p (&vr0)
1755 || symbolic_range_p (&vr1)))
1757 set_value_range_to_varying (vr);
1761 /* Now evaluate the expression to determine the new range. */
1762 if (POINTER_TYPE_P (TREE_TYPE (expr))
1763 || POINTER_TYPE_P (TREE_TYPE (op0))
1764 || POINTER_TYPE_P (TREE_TYPE (op1)))
1766 /* For pointer types, we are really only interested in asserting
1767 whether the expression evaluates to non-NULL. FIXME, we used
1768 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1769 ivopts is generating expressions with pointer multiplication
1771 if (code == PLUS_EXPR)
1773 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1774 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1775 else if (range_is_null (&vr0) && range_is_null (&vr1))
1776 set_value_range_to_null (vr, TREE_TYPE (expr));
1778 set_value_range_to_varying (vr);
1782 /* Subtracting from a pointer, may yield 0, so just drop the
1783 resulting range to varying. */
1784 set_value_range_to_varying (vr);
1790 /* For integer ranges, apply the operation to each end of the
1791 range and see what we end up with. */
1792 if (code == TRUTH_ANDIF_EXPR
1793 || code == TRUTH_ORIF_EXPR
1794 || code == TRUTH_AND_EXPR
1795 || code == TRUTH_OR_EXPR)
1797 /* If one of the operands is zero, we know that the whole
1798 expression evaluates zero. */
1799 if (code == TRUTH_AND_EXPR
1800 && ((vr0.type == VR_RANGE
1801 && integer_zerop (vr0.min)
1802 && integer_zerop (vr0.max))
1803 || (vr1.type == VR_RANGE
1804 && integer_zerop (vr1.min)
1805 && integer_zerop (vr1.max))))
1808 min = max = build_int_cst (TREE_TYPE (expr), 0);
1810 /* If one of the operands is one, we know that the whole
1811 expression evaluates one. */
1812 else if (code == TRUTH_OR_EXPR
1813 && ((vr0.type == VR_RANGE
1814 && integer_onep (vr0.min)
1815 && integer_onep (vr0.max))
1816 || (vr1.type == VR_RANGE
1817 && integer_onep (vr1.min)
1818 && integer_onep (vr1.max))))
1821 min = max = build_int_cst (TREE_TYPE (expr), 1);
1823 else if (vr0.type != VR_VARYING
1824 && vr1.type != VR_VARYING
1825 && vr0.type == vr1.type
1826 && !symbolic_range_p (&vr0)
1827 && !overflow_infinity_range_p (&vr0)
1828 && !symbolic_range_p (&vr1)
1829 && !overflow_infinity_range_p (&vr1))
1831 /* Boolean expressions cannot be folded with int_const_binop. */
1832 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1833 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1837 /* The result of a TRUTH_*_EXPR is always true or false. */
1838 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
1842 else if (code == PLUS_EXPR
1844 || code == MAX_EXPR)
1846 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1847 VR_VARYING. It would take more effort to compute a precise
1848 range for such a case. For example, if we have op0 == 1 and
1849 op1 == -1 with their ranges both being ~[0,0], we would have
1850 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1851 Note that we are guaranteed to have vr0.type == vr1.type at
1853 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1855 set_value_range_to_varying (vr);
1859 /* For operations that make the resulting range directly
1860 proportional to the original ranges, apply the operation to
1861 the same end of each range. */
1862 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1863 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1865 else if (code == MULT_EXPR
1866 || code == TRUNC_DIV_EXPR
1867 || code == FLOOR_DIV_EXPR
1868 || code == CEIL_DIV_EXPR
1869 || code == EXACT_DIV_EXPR
1870 || code == ROUND_DIV_EXPR
1871 || code == RSHIFT_EXPR)
1877 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1878 drop to VR_VARYING. It would take more effort to compute a
1879 precise range for such a case. For example, if we have
1880 op0 == 65536 and op1 == 65536 with their ranges both being
1881 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1882 we cannot claim that the product is in ~[0,0]. Note that we
1883 are guaranteed to have vr0.type == vr1.type at this
1885 if (code == MULT_EXPR
1886 && vr0.type == VR_ANTI_RANGE
1887 && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0)))
1889 set_value_range_to_varying (vr);
1893 /* If we have a RSHIFT_EXPR with any shift values outside [0..prec-1],
1894 then drop to VR_VARYING. Outside of this range we get undefined
1895 behavior from the shift operation. We cannot even trust
1896 SHIFT_COUNT_TRUNCATED at this stage, because that applies to rtl
1897 shifts, and the operation at the tree level may be widened. */
1898 if (code == RSHIFT_EXPR)
1900 if (vr1.type == VR_ANTI_RANGE
1901 || !vrp_expr_computes_nonnegative (op1, &sop)
1903 (build_int_cst (TREE_TYPE (vr1.max),
1904 TYPE_PRECISION (TREE_TYPE (expr)) - 1),
1907 set_value_range_to_varying (vr);
1912 /* Multiplications and divisions are a bit tricky to handle,
1913 depending on the mix of signs we have in the two ranges, we
1914 need to operate on different values to get the minimum and
1915 maximum values for the new range. One approach is to figure
1916 out all the variations of range combinations and do the
1919 However, this involves several calls to compare_values and it
1920 is pretty convoluted. It's simpler to do the 4 operations
1921 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1922 MAX1) and then figure the smallest and largest values to form
1925 /* Divisions by zero result in a VARYING value. */
1926 else if (code != MULT_EXPR
1927 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1929 set_value_range_to_varying (vr);
1933 /* Compute the 4 cross operations. */
1935 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1936 if (val[0] == NULL_TREE)
1939 if (vr1.max == vr1.min)
1943 val[1] = vrp_int_const_binop (code, vr0.min, vr1.max);
1944 if (val[1] == NULL_TREE)
1948 if (vr0.max == vr0.min)
1952 val[2] = vrp_int_const_binop (code, vr0.max, vr1.min);
1953 if (val[2] == NULL_TREE)
1957 if (vr0.min == vr0.max || vr1.min == vr1.max)
1961 val[3] = vrp_int_const_binop (code, vr0.max, vr1.max);
1962 if (val[3] == NULL_TREE)
1968 set_value_range_to_varying (vr);
1972 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1976 for (i = 1; i < 4; i++)
1978 if (!is_gimple_min_invariant (min)
1979 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
1980 || !is_gimple_min_invariant (max)
1981 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
1986 if (!is_gimple_min_invariant (val[i])
1987 || (TREE_OVERFLOW (val[i])
1988 && !is_overflow_infinity (val[i])))
1990 /* If we found an overflowed value, set MIN and MAX
1991 to it so that we set the resulting range to
1997 if (compare_values (val[i], min) == -1)
2000 if (compare_values (val[i], max) == 1)
2005 else if (code == MINUS_EXPR)
2007 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
2008 VR_VARYING. It would take more effort to compute a precise
2009 range for such a case. For example, if we have op0 == 1 and
2010 op1 == 1 with their ranges both being ~[0,0], we would have
2011 op0 - op1 == 0, so we cannot claim that the difference is in
2012 ~[0,0]. Note that we are guaranteed to have
2013 vr0.type == vr1.type at this point. */
2014 if (vr0.type == VR_ANTI_RANGE)
2016 set_value_range_to_varying (vr);
2020 /* For MINUS_EXPR, apply the operation to the opposite ends of
2022 min = vrp_int_const_binop (code, vr0.min, vr1.max);
2023 max = vrp_int_const_binop (code, vr0.max, vr1.min);
2025 else if (code == BIT_AND_EXPR)
2027 if (vr0.type == VR_RANGE
2028 && vr0.min == vr0.max
2029 && TREE_CODE (vr0.max) == INTEGER_CST
2030 && !TREE_OVERFLOW (vr0.max)
2031 && tree_int_cst_sgn (vr0.max) >= 0)
2033 min = build_int_cst (TREE_TYPE (expr), 0);
2036 else if (vr1.type == VR_RANGE
2037 && vr1.min == vr1.max
2038 && TREE_CODE (vr1.max) == INTEGER_CST
2039 && !TREE_OVERFLOW (vr1.max)
2040 && tree_int_cst_sgn (vr1.max) >= 0)
2043 min = build_int_cst (TREE_TYPE (expr), 0);
2048 set_value_range_to_varying (vr);
2055 /* If either MIN or MAX overflowed, then set the resulting range to
2056 VARYING. But we do accept an overflow infinity
2058 if (min == NULL_TREE
2059 || !is_gimple_min_invariant (min)
2060 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
2062 || !is_gimple_min_invariant (max)
2063 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
2065 set_value_range_to_varying (vr);
2071 2) [-INF, +-INF(OVF)]
2072 3) [+-INF(OVF), +INF]
2073 4) [+-INF(OVF), +-INF(OVF)]
2074 We learn nothing when we have INF and INF(OVF) on both sides.
2075 Note that we do accept [-INF, -INF] and [+INF, +INF] without
2077 if ((vrp_val_is_min (min) || is_overflow_infinity (min))
2078 && (vrp_val_is_max (max) || is_overflow_infinity (max)))
2080 set_value_range_to_varying (vr);
2084 cmp = compare_values (min, max);
2085 if (cmp == -2 || cmp == 1)
2087 /* If the new range has its limits swapped around (MIN > MAX),
2088 then the operation caused one of them to wrap around, mark
2089 the new range VARYING. */
2090 set_value_range_to_varying (vr);
2093 set_value_range (vr, type, min, max, NULL);
2097 /* Extract range information from a unary expression EXPR based on
2098 the range of its operand and the expression code. */
2101 extract_range_from_unary_expr (value_range_t *vr, tree expr)
2103 enum tree_code code = TREE_CODE (expr);
2106 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2108 /* Refuse to operate on certain unary expressions for which we
2109 cannot easily determine a resulting range. */
2110 if (code == FIX_TRUNC_EXPR
2111 || code == FLOAT_EXPR
2112 || code == BIT_NOT_EXPR
2113 || code == NON_LVALUE_EXPR
2114 || code == CONJ_EXPR)
2116 set_value_range_to_varying (vr);
2120 /* Get value ranges for the operand. For constant operands, create
2121 a new value range with the operand to simplify processing. */
2122 op0 = TREE_OPERAND (expr, 0);
2123 if (TREE_CODE (op0) == SSA_NAME)
2124 vr0 = *(get_value_range (op0));
2125 else if (is_gimple_min_invariant (op0))
2126 set_value_range_to_value (&vr0, op0, NULL);
2128 set_value_range_to_varying (&vr0);
2130 /* If VR0 is UNDEFINED, so is the result. */
2131 if (vr0.type == VR_UNDEFINED)
2133 set_value_range_to_undefined (vr);
2137 /* Refuse to operate on symbolic ranges, or if neither operand is
2138 a pointer or integral type. */
2139 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0))
2140 && !POINTER_TYPE_P (TREE_TYPE (op0)))
2141 || (vr0.type != VR_VARYING
2142 && symbolic_range_p (&vr0)))
2144 set_value_range_to_varying (vr);
2148 /* If the expression involves pointers, we are only interested in
2149 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
2150 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
2155 if (range_is_nonnull (&vr0)
2156 || (tree_expr_nonzero_warnv_p (expr, &sop)
2158 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
2159 else if (range_is_null (&vr0))
2160 set_value_range_to_null (vr, TREE_TYPE (expr));
2162 set_value_range_to_varying (vr);
2167 /* Handle unary expressions on integer ranges. */
2168 if (code == NOP_EXPR || code == CONVERT_EXPR)
2170 tree inner_type = TREE_TYPE (op0);
2171 tree outer_type = TREE_TYPE (expr);
2173 /* If VR0 represents a simple range, then try to convert
2174 the min and max values for the range to the same type
2175 as OUTER_TYPE. If the results compare equal to VR0's
2176 min and max values and the new min is still less than
2177 or equal to the new max, then we can safely use the newly
2178 computed range for EXPR. This allows us to compute
2179 accurate ranges through many casts. */
2180 if ((vr0.type == VR_RANGE
2181 && !overflow_infinity_range_p (&vr0))
2182 || (vr0.type == VR_VARYING
2183 && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type)))
2185 tree new_min, new_max, orig_min, orig_max;
2187 /* Convert the input operand min/max to OUTER_TYPE. If
2188 the input has no range information, then use the min/max
2189 for the input's type. */
2190 if (vr0.type == VR_RANGE)
2197 orig_min = TYPE_MIN_VALUE (inner_type);
2198 orig_max = TYPE_MAX_VALUE (inner_type);
2201 new_min = fold_convert (outer_type, orig_min);
2202 new_max = fold_convert (outer_type, orig_max);
2204 /* Verify the new min/max values are gimple values and
2205 that they compare equal to the original input's
2207 if (is_gimple_val (new_min)
2208 && is_gimple_val (new_max)
2209 && tree_int_cst_equal (new_min, orig_min)
2210 && tree_int_cst_equal (new_max, orig_max)
2211 && (cmp = compare_values (new_min, new_max)) <= 0
2214 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
2219 /* When converting types of different sizes, set the result to
2220 VARYING. Things like sign extensions and precision loss may
2221 change the range. For instance, if x_3 is of type 'long long
2222 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
2223 is impossible to know at compile time whether y_5 will be
2225 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
2226 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
2228 set_value_range_to_varying (vr);
2233 /* Conversion of a VR_VARYING value to a wider type can result
2234 in a usable range. So wait until after we've handled conversions
2235 before dropping the result to VR_VARYING if we had a source
2236 operand that is VR_VARYING. */
2237 if (vr0.type == VR_VARYING)
2239 set_value_range_to_varying (vr);
2243 /* Apply the operation to each end of the range and see what we end
2245 if (code == NEGATE_EXPR
2246 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
2248 /* NEGATE_EXPR flips the range around. We need to treat
2249 TYPE_MIN_VALUE specially. */
2250 if (is_positive_overflow_infinity (vr0.max))
2251 min = negative_overflow_infinity (TREE_TYPE (expr));
2252 else if (is_negative_overflow_infinity (vr0.max))
2253 min = positive_overflow_infinity (TREE_TYPE (expr));
2254 else if (!vrp_val_is_min (vr0.max))
2255 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2256 else if (needs_overflow_infinity (TREE_TYPE (expr)))
2258 if (supports_overflow_infinity (TREE_TYPE (expr))
2259 && !is_overflow_infinity (vr0.min)
2260 && !vrp_val_is_min (vr0.min))
2261 min = positive_overflow_infinity (TREE_TYPE (expr));
2264 set_value_range_to_varying (vr);
2269 min = TYPE_MIN_VALUE (TREE_TYPE (expr));
2271 if (is_positive_overflow_infinity (vr0.min))
2272 max = negative_overflow_infinity (TREE_TYPE (expr));
2273 else if (is_negative_overflow_infinity (vr0.min))
2274 max = positive_overflow_infinity (TREE_TYPE (expr));
2275 else if (!vrp_val_is_min (vr0.min))
2276 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2277 else if (needs_overflow_infinity (TREE_TYPE (expr)))
2279 if (supports_overflow_infinity (TREE_TYPE (expr)))
2280 max = positive_overflow_infinity (TREE_TYPE (expr));
2283 set_value_range_to_varying (vr);
2288 max = TYPE_MIN_VALUE (TREE_TYPE (expr));
2290 else if (code == NEGATE_EXPR
2291 && TYPE_UNSIGNED (TREE_TYPE (expr)))
2293 if (!range_includes_zero_p (&vr0))
2295 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2296 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2300 if (range_is_null (&vr0))
2301 set_value_range_to_null (vr, TREE_TYPE (expr));
2303 set_value_range_to_varying (vr);
2307 else if (code == ABS_EXPR
2308 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
2310 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
2312 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (expr))
2313 && ((vr0.type == VR_RANGE
2314 && vrp_val_is_min (vr0.min))
2315 || (vr0.type == VR_ANTI_RANGE
2316 && !vrp_val_is_min (vr0.min)
2317 && !range_includes_zero_p (&vr0))))
2319 set_value_range_to_varying (vr);
2323 /* ABS_EXPR may flip the range around, if the original range
2324 included negative values. */
2325 if (is_overflow_infinity (vr0.min))
2326 min = positive_overflow_infinity (TREE_TYPE (expr));
2327 else if (!vrp_val_is_min (vr0.min))
2328 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2329 else if (!needs_overflow_infinity (TREE_TYPE (expr)))
2330 min = TYPE_MAX_VALUE (TREE_TYPE (expr));
2331 else if (supports_overflow_infinity (TREE_TYPE (expr)))
2332 min = positive_overflow_infinity (TREE_TYPE (expr));
2335 set_value_range_to_varying (vr);
2339 if (is_overflow_infinity (vr0.max))
2340 max = positive_overflow_infinity (TREE_TYPE (expr));
2341 else if (!vrp_val_is_min (vr0.max))
2342 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2343 else if (!needs_overflow_infinity (TREE_TYPE (expr)))
2344 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
2345 else if (supports_overflow_infinity (TREE_TYPE (expr)))
2346 max = positive_overflow_infinity (TREE_TYPE (expr));
2349 set_value_range_to_varying (vr);
2353 cmp = compare_values (min, max);
2355 /* If a VR_ANTI_RANGEs contains zero, then we have
2356 ~[-INF, min(MIN, MAX)]. */
2357 if (vr0.type == VR_ANTI_RANGE)
2359 if (range_includes_zero_p (&vr0))
2361 /* Take the lower of the two values. */
2365 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
2366 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
2367 flag_wrapv is set and the original anti-range doesn't include
2368 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
2369 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr)))
2371 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
2373 min = (vr0.min != type_min_value
2374 ? int_const_binop (PLUS_EXPR, type_min_value,
2375 integer_one_node, 0)
2380 if (overflow_infinity_range_p (&vr0))
2381 min = negative_overflow_infinity (TREE_TYPE (expr));
2383 min = TYPE_MIN_VALUE (TREE_TYPE (expr));
2388 /* All else has failed, so create the range [0, INF], even for
2389 flag_wrapv since TYPE_MIN_VALUE is in the original
2391 vr0.type = VR_RANGE;
2392 min = build_int_cst (TREE_TYPE (expr), 0);
2393 if (needs_overflow_infinity (TREE_TYPE (expr)))
2395 if (supports_overflow_infinity (TREE_TYPE (expr)))
2396 max = positive_overflow_infinity (TREE_TYPE (expr));
2399 set_value_range_to_varying (vr);
2404 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
2408 /* If the range contains zero then we know that the minimum value in the
2409 range will be zero. */
2410 else if (range_includes_zero_p (&vr0))
2414 min = build_int_cst (TREE_TYPE (expr), 0);
2418 /* If the range was reversed, swap MIN and MAX. */
2429 /* Otherwise, operate on each end of the range. */
2430 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2431 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2433 if (needs_overflow_infinity (TREE_TYPE (expr)))
2435 gcc_assert (code != NEGATE_EXPR && code != ABS_EXPR);
2437 /* If both sides have overflowed, we don't know
2439 if ((is_overflow_infinity (vr0.min)
2440 || TREE_OVERFLOW (min))
2441 && (is_overflow_infinity (vr0.max)
2442 || TREE_OVERFLOW (max)))
2444 set_value_range_to_varying (vr);
2448 if (is_overflow_infinity (vr0.min))
2450 else if (TREE_OVERFLOW (min))
2452 if (supports_overflow_infinity (TREE_TYPE (expr)))
2453 min = (tree_int_cst_sgn (min) >= 0
2454 ? positive_overflow_infinity (TREE_TYPE (min))
2455 : negative_overflow_infinity (TREE_TYPE (min)));
2458 set_value_range_to_varying (vr);
2463 if (is_overflow_infinity (vr0.max))
2465 else if (TREE_OVERFLOW (max))
2467 if (supports_overflow_infinity (TREE_TYPE (expr)))
2468 max = (tree_int_cst_sgn (max) >= 0
2469 ? positive_overflow_infinity (TREE_TYPE (max))
2470 : negative_overflow_infinity (TREE_TYPE (max)));
2473 set_value_range_to_varying (vr);
2480 cmp = compare_values (min, max);
2481 if (cmp == -2 || cmp == 1)
2483 /* If the new range has its limits swapped around (MIN > MAX),
2484 then the operation caused one of them to wrap around, mark
2485 the new range VARYING. */
2486 set_value_range_to_varying (vr);
2489 set_value_range (vr, vr0.type, min, max, NULL);
2493 /* Extract range information from a conditional expression EXPR based on
2494 the ranges of each of its operands and the expression code. */
2497 extract_range_from_cond_expr (value_range_t *vr, tree expr)
2500 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2501 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2503 /* Get value ranges for each operand. For constant operands, create
2504 a new value range with the operand to simplify processing. */
2505 op0 = COND_EXPR_THEN (expr);
2506 if (TREE_CODE (op0) == SSA_NAME)
2507 vr0 = *(get_value_range (op0));
2508 else if (is_gimple_min_invariant (op0))
2509 set_value_range_to_value (&vr0, op0, NULL);
2511 set_value_range_to_varying (&vr0);
2513 op1 = COND_EXPR_ELSE (expr);
2514 if (TREE_CODE (op1) == SSA_NAME)
2515 vr1 = *(get_value_range (op1));
2516 else if (is_gimple_min_invariant (op1))
2517 set_value_range_to_value (&vr1, op1, NULL);
2519 set_value_range_to_varying (&vr1);
2521 /* The resulting value range is the union of the operand ranges */
2522 vrp_meet (&vr0, &vr1);
2523 copy_value_range (vr, &vr0);
2527 /* Extract range information from a comparison expression EXPR based
2528 on the range of its operand and the expression code. */
2531 extract_range_from_comparison (value_range_t *vr, tree expr)
2534 tree val = vrp_evaluate_conditional_warnv (expr, false, &sop);
2536 /* A disadvantage of using a special infinity as an overflow
2537 representation is that we lose the ability to record overflow
2538 when we don't have an infinity. So we have to ignore a result
2539 which relies on overflow. */
2541 if (val && !is_overflow_infinity (val) && !sop)
2543 /* Since this expression was found on the RHS of an assignment,
2544 its type may be different from _Bool. Convert VAL to EXPR's
2546 val = fold_convert (TREE_TYPE (expr), val);
2547 if (is_gimple_min_invariant (val))
2548 set_value_range_to_value (vr, val, vr->equiv);
2550 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
2553 /* The result of a comparison is always true or false. */
2554 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
2558 /* Try to compute a useful range out of expression EXPR and store it
2562 extract_range_from_expr (value_range_t *vr, tree expr)
2564 enum tree_code code = TREE_CODE (expr);
2566 if (code == ASSERT_EXPR)
2567 extract_range_from_assert (vr, expr);
2568 else if (code == SSA_NAME)
2569 extract_range_from_ssa_name (vr, expr);
2570 else if (TREE_CODE_CLASS (code) == tcc_binary
2571 || code == TRUTH_ANDIF_EXPR
2572 || code == TRUTH_ORIF_EXPR
2573 || code == TRUTH_AND_EXPR
2574 || code == TRUTH_OR_EXPR
2575 || code == TRUTH_XOR_EXPR)
2576 extract_range_from_binary_expr (vr, expr);
2577 else if (TREE_CODE_CLASS (code) == tcc_unary)
2578 extract_range_from_unary_expr (vr, expr);
2579 else if (code == COND_EXPR)
2580 extract_range_from_cond_expr (vr, expr);
2581 else if (TREE_CODE_CLASS (code) == tcc_comparison)
2582 extract_range_from_comparison (vr, expr);
2583 else if (is_gimple_min_invariant (expr))
2584 set_value_range_to_value (vr, expr, NULL);
2586 set_value_range_to_varying (vr);
2588 /* If we got a varying range from the tests above, try a final
2589 time to derive a nonnegative or nonzero range. This time
2590 relying primarily on generic routines in fold in conjunction
2592 if (vr->type == VR_VARYING)
2596 if (INTEGRAL_TYPE_P (TREE_TYPE (expr))
2597 && vrp_expr_computes_nonnegative (expr, &sop))
2598 set_value_range_to_nonnegative (vr, TREE_TYPE (expr),
2599 sop || is_overflow_infinity (expr));
2600 else if (vrp_expr_computes_nonzero (expr, &sop)
2602 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
2606 /* Given a range VR, a LOOP and a variable VAR, determine whether it
2607 would be profitable to adjust VR using scalar evolution information
2608 for VAR. If so, update VR with the new limits. */
2611 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
2614 tree init, step, chrec, tmin, tmax, min, max, type;
2615 enum ev_direction dir;
2617 /* TODO. Don't adjust anti-ranges. An anti-range may provide
2618 better opportunities than a regular range, but I'm not sure. */
2619 if (vr->type == VR_ANTI_RANGE)
2622 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
2623 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
2626 init = initial_condition_in_loop_num (chrec, loop->num);
2627 step = evolution_part_in_loop_num (chrec, loop->num);
2629 /* If STEP is symbolic, we can't know whether INIT will be the
2630 minimum or maximum value in the range. Also, unless INIT is
2631 a simple expression, compare_values and possibly other functions
2632 in tree-vrp won't be able to handle it. */
2633 if (step == NULL_TREE
2634 || !is_gimple_min_invariant (step)
2635 || !valid_value_p (init))
2638 dir = scev_direction (chrec);
2639 if (/* Do not adjust ranges if we do not know whether the iv increases
2640 or decreases, ... */
2641 dir == EV_DIR_UNKNOWN
2642 /* ... or if it may wrap. */
2643 || scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec),
2647 /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of
2648 negative_overflow_infinity and positive_overflow_infinity,
2649 because we have concluded that the loop probably does not
2652 type = TREE_TYPE (var);
2653 if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type))
2654 tmin = lower_bound_in_type (type, type);
2656 tmin = TYPE_MIN_VALUE (type);
2657 if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type))
2658 tmax = upper_bound_in_type (type, type);
2660 tmax = TYPE_MAX_VALUE (type);
2662 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2667 /* For VARYING or UNDEFINED ranges, just about anything we get
2668 from scalar evolutions should be better. */
2670 if (dir == EV_DIR_DECREASES)
2675 /* If we would create an invalid range, then just assume we
2676 know absolutely nothing. This may be over-conservative,
2677 but it's clearly safe, and should happen only in unreachable
2678 parts of code, or for invalid programs. */
2679 if (compare_values (min, max) == 1)
2682 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2684 else if (vr->type == VR_RANGE)
2689 if (dir == EV_DIR_DECREASES)
2691 /* INIT is the maximum value. If INIT is lower than VR->MAX
2692 but no smaller than VR->MIN, set VR->MAX to INIT. */
2693 if (compare_values (init, max) == -1)
2697 /* If we just created an invalid range with the minimum
2698 greater than the maximum, we fail conservatively.
2699 This should happen only in unreachable
2700 parts of code, or for invalid programs. */
2701 if (compare_values (min, max) == 1)
2705 /* According to the loop information, the variable does not
2706 overflow. If we think it does, probably because of an
2707 overflow due to arithmetic on a different INF value,
2709 if (is_negative_overflow_infinity (min))
2714 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2715 if (compare_values (init, min) == 1)
2719 /* Again, avoid creating invalid range by failing. */
2720 if (compare_values (min, max) == 1)
2724 if (is_positive_overflow_infinity (max))
2728 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2732 /* Return true if VAR may overflow at STMT. This checks any available
2733 loop information to see if we can determine that VAR does not
2737 vrp_var_may_overflow (tree var, tree stmt)
2740 tree chrec, init, step;
2742 if (current_loops == NULL)
2745 l = loop_containing_stmt (stmt);
2749 chrec = instantiate_parameters (l, analyze_scalar_evolution (l, var));
2750 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
2753 init = initial_condition_in_loop_num (chrec, l->num);
2754 step = evolution_part_in_loop_num (chrec, l->num);
2756 if (step == NULL_TREE
2757 || !is_gimple_min_invariant (step)
2758 || !valid_value_p (init))
2761 /* If we get here, we know something useful about VAR based on the
2762 loop information. If it wraps, it may overflow. */
2764 if (scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec),
2768 if (dump_file && (dump_flags & TDF_DETAILS) != 0)
2770 print_generic_expr (dump_file, var, 0);
2771 fprintf (dump_file, ": loop information indicates does not overflow\n");
2778 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2780 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2781 all the values in the ranges.
2783 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2785 - Return NULL_TREE if it is not always possible to determine the
2786 value of the comparison.
2788 Also set *STRICT_OVERFLOW_P to indicate whether a range with an
2789 overflow infinity was used in the test. */
2793 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1,
2794 bool *strict_overflow_p)
2796 /* VARYING or UNDEFINED ranges cannot be compared. */
2797 if (vr0->type == VR_VARYING
2798 || vr0->type == VR_UNDEFINED
2799 || vr1->type == VR_VARYING
2800 || vr1->type == VR_UNDEFINED)
2803 /* Anti-ranges need to be handled separately. */
2804 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
2806 /* If both are anti-ranges, then we cannot compute any
2808 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
2811 /* These comparisons are never statically computable. */
2818 /* Equality can be computed only between a range and an
2819 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2820 if (vr0->type == VR_RANGE)
2822 /* To simplify processing, make VR0 the anti-range. */
2823 value_range_t *tmp = vr0;
2828 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
2830 if (compare_values_warnv (vr0->min, vr1->min, strict_overflow_p) == 0
2831 && compare_values_warnv (vr0->max, vr1->max, strict_overflow_p) == 0)
2832 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2837 if (!usable_range_p (vr0, strict_overflow_p)
2838 || !usable_range_p (vr1, strict_overflow_p))
2841 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2842 operands around and change the comparison code. */
2843 if (comp == GT_EXPR || comp == GE_EXPR)
2846 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
2852 if (comp == EQ_EXPR)
2854 /* Equality may only be computed if both ranges represent
2855 exactly one value. */
2856 if (compare_values_warnv (vr0->min, vr0->max, strict_overflow_p) == 0
2857 && compare_values_warnv (vr1->min, vr1->max, strict_overflow_p) == 0)
2859 int cmp_min = compare_values_warnv (vr0->min, vr1->min,
2861 int cmp_max = compare_values_warnv (vr0->max, vr1->max,
2863 if (cmp_min == 0 && cmp_max == 0)
2864 return boolean_true_node;
2865 else if (cmp_min != -2 && cmp_max != -2)
2866 return boolean_false_node;
2868 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2869 else if (compare_values_warnv (vr0->min, vr1->max,
2870 strict_overflow_p) == 1
2871 || compare_values_warnv (vr1->min, vr0->max,
2872 strict_overflow_p) == 1)
2873 return boolean_false_node;
2877 else if (comp == NE_EXPR)
2881 /* If VR0 is completely to the left or completely to the right
2882 of VR1, they are always different. Notice that we need to
2883 make sure that both comparisons yield similar results to
2884 avoid comparing values that cannot be compared at
2886 cmp1 = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
2887 cmp2 = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
2888 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
2889 return boolean_true_node;
2891 /* If VR0 and VR1 represent a single value and are identical,
2893 else if (compare_values_warnv (vr0->min, vr0->max,
2894 strict_overflow_p) == 0
2895 && compare_values_warnv (vr1->min, vr1->max,
2896 strict_overflow_p) == 0
2897 && compare_values_warnv (vr0->min, vr1->min,
2898 strict_overflow_p) == 0
2899 && compare_values_warnv (vr0->max, vr1->max,
2900 strict_overflow_p) == 0)
2901 return boolean_false_node;
2903 /* Otherwise, they may or may not be different. */
2907 else if (comp == LT_EXPR || comp == LE_EXPR)
2911 /* If VR0 is to the left of VR1, return true. */
2912 tst = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
2913 if ((comp == LT_EXPR && tst == -1)
2914 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2916 if (overflow_infinity_range_p (vr0)
2917 || overflow_infinity_range_p (vr1))
2918 *strict_overflow_p = true;
2919 return boolean_true_node;
2922 /* If VR0 is to the right of VR1, return false. */
2923 tst = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
2924 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2925 || (comp == LE_EXPR && tst == 1))
2927 if (overflow_infinity_range_p (vr0)
2928 || overflow_infinity_range_p (vr1))
2929 *strict_overflow_p = true;
2930 return boolean_false_node;
2933 /* Otherwise, we don't know. */
2941 /* Given a value range VR, a value VAL and a comparison code COMP, return
2942 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2943 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2944 always returns false. Return NULL_TREE if it is not always
2945 possible to determine the value of the comparison. Also set
2946 *STRICT_OVERFLOW_P to indicate whether a range with an overflow
2947 infinity was used in the test. */
2950 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val,
2951 bool *strict_overflow_p)
2953 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2956 /* Anti-ranges need to be handled separately. */
2957 if (vr->type == VR_ANTI_RANGE)
2959 /* For anti-ranges, the only predicates that we can compute at
2960 compile time are equality and inequality. */
2967 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2968 if (value_inside_range (val, vr) == 1)
2969 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2974 if (!usable_range_p (vr, strict_overflow_p))
2977 if (comp == EQ_EXPR)
2979 /* EQ_EXPR may only be computed if VR represents exactly
2981 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0)
2983 int cmp = compare_values_warnv (vr->min, val, strict_overflow_p);
2985 return boolean_true_node;
2986 else if (cmp == -1 || cmp == 1 || cmp == 2)
2987 return boolean_false_node;
2989 else if (compare_values_warnv (val, vr->min, strict_overflow_p) == -1
2990 || compare_values_warnv (vr->max, val, strict_overflow_p) == -1)
2991 return boolean_false_node;
2995 else if (comp == NE_EXPR)
2997 /* If VAL is not inside VR, then they are always different. */
2998 if (compare_values_warnv (vr->max, val, strict_overflow_p) == -1
2999 || compare_values_warnv (vr->min, val, strict_overflow_p) == 1)
3000 return boolean_true_node;
3002 /* If VR represents exactly one value equal to VAL, then return
3004 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0
3005 && compare_values_warnv (vr->min, val, strict_overflow_p) == 0)
3006 return boolean_false_node;
3008 /* Otherwise, they may or may not be different. */
3011 else if (comp == LT_EXPR || comp == LE_EXPR)
3015 /* If VR is to the left of VAL, return true. */
3016 tst = compare_values_warnv (vr->max, val, strict_overflow_p);
3017 if ((comp == LT_EXPR && tst == -1)
3018 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
3020 if (overflow_infinity_range_p (vr))
3021 *strict_overflow_p = true;
3022 return boolean_true_node;
3025 /* If VR is to the right of VAL, return false. */
3026 tst = compare_values_warnv (vr->min, val, strict_overflow_p);
3027 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
3028 || (comp == LE_EXPR && tst == 1))
3030 if (overflow_infinity_range_p (vr))
3031 *strict_overflow_p = true;
3032 return boolean_false_node;
3035 /* Otherwise, we don't know. */
3038 else if (comp == GT_EXPR || comp == GE_EXPR)
3042 /* If VR is to the right of VAL, return true. */
3043 tst = compare_values_warnv (vr->min, val, strict_overflow_p);
3044 if ((comp == GT_EXPR && tst == 1)
3045 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
3047 if (overflow_infinity_range_p (vr))
3048 *strict_overflow_p = true;
3049 return boolean_true_node;
3052 /* If VR is to the left of VAL, return false. */
3053 tst = compare_values_warnv (vr->max, val, strict_overflow_p);
3054 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
3055 || (comp == GE_EXPR && tst == -1))
3057 if (overflow_infinity_range_p (vr))
3058 *strict_overflow_p = true;
3059 return boolean_false_node;
3062 /* Otherwise, we don't know. */
3070 /* Debugging dumps. */
3072 void dump_value_range (FILE *, value_range_t *);
3073 void debug_value_range (value_range_t *);
3074 void dump_all_value_ranges (FILE *);
3075 void debug_all_value_ranges (void);
3076 void dump_vr_equiv (FILE *, bitmap);
3077 void debug_vr_equiv (bitmap);
3080 /* Dump value range VR to FILE. */
3083 dump_value_range (FILE *file, value_range_t *vr)
3086 fprintf (file, "[]");
3087 else if (vr->type == VR_UNDEFINED)
3088 fprintf (file, "UNDEFINED");
3089 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
3091 tree type = TREE_TYPE (vr->min);
3093 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
3095 if (is_negative_overflow_infinity (vr->min))
3096 fprintf (file, "-INF(OVF)");
3097 else if (INTEGRAL_TYPE_P (type)
3098 && !TYPE_UNSIGNED (type)
3099 && vrp_val_is_min (vr->min))
3100 fprintf (file, "-INF");
3102 print_generic_expr (file, vr->min, 0);
3104 fprintf (file, ", ");
3106 if (is_positive_overflow_infinity (vr->max))
3107 fprintf (file, "+INF(OVF)");
3108 else if (INTEGRAL_TYPE_P (type)
3109 && vrp_val_is_max (vr->max))
3110 fprintf (file, "+INF");
3112 print_generic_expr (file, vr->max, 0);
3114 fprintf (file, "]");
3121 fprintf (file, " EQUIVALENCES: { ");
3123 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
3125 print_generic_expr (file, ssa_name (i), 0);
3126 fprintf (file, " ");
3130 fprintf (file, "} (%u elements)", c);
3133 else if (vr->type == VR_VARYING)
3134 fprintf (file, "VARYING");
3136 fprintf (file, "INVALID RANGE");
3140 /* Dump value range VR to stderr. */
3143 debug_value_range (value_range_t *vr)
3145 dump_value_range (stderr, vr);
3146 fprintf (stderr, "\n");
3150 /* Dump value ranges of all SSA_NAMEs to FILE. */
3153 dump_all_value_ranges (FILE *file)
3157 for (i = 0; i < num_ssa_names; i++)
3161 print_generic_expr (file, ssa_name (i), 0);
3162 fprintf (file, ": ");
3163 dump_value_range (file, vr_value[i]);
3164 fprintf (file, "\n");
3168 fprintf (file, "\n");
3172 /* Dump all value ranges to stderr. */
3175 debug_all_value_ranges (void)
3177 dump_all_value_ranges (stderr);
3181 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
3182 create a new SSA name N and return the assertion assignment
3183 'V = ASSERT_EXPR <V, V OP W>'. */
3186 build_assert_expr_for (tree cond, tree v)
3190 gcc_assert (TREE_CODE (v) == SSA_NAME);
3191 n = duplicate_ssa_name (v, NULL_TREE);
3193 if (COMPARISON_CLASS_P (cond))
3195 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
3196 assertion = build_gimple_modify_stmt (n, a);
3198 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
3200 /* Given !V, build the assignment N = false. */
3201 tree op0 = TREE_OPERAND (cond, 0);
3202 gcc_assert (op0 == v);
3203 assertion = build_gimple_modify_stmt (n, boolean_false_node);
3205 else if (TREE_CODE (cond) == SSA_NAME)
3207 /* Given V, build the assignment N = true. */
3208 gcc_assert (v == cond);
3209 assertion = build_gimple_modify_stmt (n, boolean_true_node);
3214 SSA_NAME_DEF_STMT (n) = assertion;
3216 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
3217 operand of the ASSERT_EXPR. Register the new name and the old one
3218 in the replacement table so that we can fix the SSA web after
3219 adding all the ASSERT_EXPRs. */
3220 register_new_name_mapping (n, v);
3226 /* Return false if EXPR is a predicate expression involving floating
3230 fp_predicate (tree expr)
3232 return (COMPARISON_CLASS_P (expr)
3233 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
3237 /* If the range of values taken by OP can be inferred after STMT executes,
3238 return the comparison code (COMP_CODE_P) and value (VAL_P) that
3239 describes the inferred range. Return true if a range could be
3243 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
3246 *comp_code_p = ERROR_MARK;
3248 /* Do not attempt to infer anything in names that flow through
3250 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
3253 /* Similarly, don't infer anything from statements that may throw
3255 if (tree_could_throw_p (stmt))
3258 /* If STMT is the last statement of a basic block with no
3259 successors, there is no point inferring anything about any of its
3260 operands. We would not be able to find a proper insertion point
3261 for the assertion, anyway. */
3262 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
3265 /* We can only assume that a pointer dereference will yield
3266 non-NULL if -fdelete-null-pointer-checks is enabled. */
3267 if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op)))
3269 unsigned num_uses, num_loads, num_stores;
3271 count_uses_and_derefs (op, stmt, &num_uses, &num_loads, &num_stores);
3272 if (num_loads + num_stores > 0)
3274 *val_p = build_int_cst (TREE_TYPE (op), 0);
3275 *comp_code_p = NE_EXPR;
3284 void dump_asserts_for (FILE *, tree);
3285 void debug_asserts_for (tree);
3286 void dump_all_asserts (FILE *);
3287 void debug_all_asserts (void);
3289 /* Dump all the registered assertions for NAME to FILE. */
3292 dump_asserts_for (FILE *file, tree name)
3296 fprintf (file, "Assertions to be inserted for ");
3297 print_generic_expr (file, name, 0);
3298 fprintf (file, "\n");
3300 loc = asserts_for[SSA_NAME_VERSION (name)];
3303 fprintf (file, "\t");
3304 print_generic_expr (file, bsi_stmt (loc->si), 0);
3305 fprintf (file, "\n\tBB #%d", loc->bb->index);
3308 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
3309 loc->e->dest->index);
3310 dump_edge_info (file, loc->e, 0);
3312 fprintf (file, "\n\tPREDICATE: ");
3313 print_generic_expr (file, name, 0);
3314 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
3315 print_generic_expr (file, loc->val, 0);
3316 fprintf (file, "\n\n");
3320 fprintf (file, "\n");
3324 /* Dump all the registered assertions for NAME to stderr. */
3327 debug_asserts_for (tree name)
3329 dump_asserts_for (stderr, name);
3333 /* Dump all the registered assertions for all the names to FILE. */
3336 dump_all_asserts (FILE *file)
3341 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
3342 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3343 dump_asserts_for (file, ssa_name (i));
3344 fprintf (file, "\n");
3348 /* Dump all the registered assertions for all the names to stderr. */
3351 debug_all_asserts (void)
3353 dump_all_asserts (stderr);
3357 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
3358 'NAME COMP_CODE VAL' at a location that dominates block BB or
3359 E->DEST, then register this location as a possible insertion point
3360 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
3362 BB, E and SI provide the exact insertion point for the new
3363 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
3364 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
3365 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
3366 must not be NULL. */
3369 register_new_assert_for (tree name,
3370 enum tree_code comp_code,
3374 block_stmt_iterator si)
3376 assert_locus_t n, loc, last_loc;
3378 basic_block dest_bb;
3380 #if defined ENABLE_CHECKING
3381 gcc_assert (bb == NULL || e == NULL);
3384 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
3385 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
3388 /* The new assertion A will be inserted at BB or E. We need to
3389 determine if the new location is dominated by a previously
3390 registered location for A. If we are doing an edge insertion,
3391 assume that A will be inserted at E->DEST. Note that this is not
3394 If E is a critical edge, it will be split. But even if E is
3395 split, the new block will dominate the same set of blocks that
3398 The reverse, however, is not true, blocks dominated by E->DEST
3399 will not be dominated by the new block created to split E. So,
3400 if the insertion location is on a critical edge, we will not use
3401 the new location to move another assertion previously registered
3402 at a block dominated by E->DEST. */
3403 dest_bb = (bb) ? bb : e->dest;
3405 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
3406 VAL at a block dominating DEST_BB, then we don't need to insert a new
3407 one. Similarly, if the same assertion already exists at a block
3408 dominated by DEST_BB and the new location is not on a critical
3409 edge, then update the existing location for the assertion (i.e.,
3410 move the assertion up in the dominance tree).
3412 Note, this is implemented as a simple linked list because there
3413 should not be more than a handful of assertions registered per
3414 name. If this becomes a performance problem, a table hashed by
3415 COMP_CODE and VAL could be implemented. */
3416 loc = asserts_for[SSA_NAME_VERSION (name)];
3421 if (loc->comp_code == comp_code
3423 || operand_equal_p (loc->val, val, 0)))
3425 /* If the assertion NAME COMP_CODE VAL has already been
3426 registered at a basic block that dominates DEST_BB, then
3427 we don't need to insert the same assertion again. Note
3428 that we don't check strict dominance here to avoid
3429 replicating the same assertion inside the same basic
3430 block more than once (e.g., when a pointer is
3431 dereferenced several times inside a block).
3433 An exception to this rule are edge insertions. If the
3434 new assertion is to be inserted on edge E, then it will
3435 dominate all the other insertions that we may want to
3436 insert in DEST_BB. So, if we are doing an edge
3437 insertion, don't do this dominance check. */
3439 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
3442 /* Otherwise, if E is not a critical edge and DEST_BB
3443 dominates the existing location for the assertion, move
3444 the assertion up in the dominance tree by updating its
3445 location information. */
3446 if ((e == NULL || !EDGE_CRITICAL_P (e))
3447 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
3456 /* Update the last node of the list and move to the next one. */
3461 /* If we didn't find an assertion already registered for
3462 NAME COMP_CODE VAL, add a new one at the end of the list of
3463 assertions associated with NAME. */
3464 n = XNEW (struct assert_locus_d);
3468 n->comp_code = comp_code;
3475 asserts_for[SSA_NAME_VERSION (name)] = n;
3477 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
3480 /* COND is a predicate which uses NAME. Extract a suitable test code
3481 and value and store them into *CODE_P and *VAL_P so the predicate
3482 is normalized to NAME *CODE_P *VAL_P.
3484 If no extraction was possible, return FALSE, otherwise return TRUE.
3486 If INVERT is true, then we invert the result stored into *CODE_P. */
3489 extract_code_and_val_from_cond (tree name, tree cond, bool invert,
3490 enum tree_code *code_p, tree *val_p)
3492 enum tree_code comp_code;
3495 /* Predicates may be a single SSA name or NAME OP VAL. */
3498 /* If the predicate is a name, it must be NAME, in which
3499 case we create the predicate NAME == true or
3500 NAME == false accordingly. */
3501 comp_code = EQ_EXPR;
3502 val = invert ? boolean_false_node : boolean_true_node;
3506 /* Otherwise, we have a comparison of the form NAME COMP VAL
3507 or VAL COMP NAME. */
3508 if (name == TREE_OPERAND (cond, 1))
3510 /* If the predicate is of the form VAL COMP NAME, flip
3511 COMP around because we need to register NAME as the
3512 first operand in the predicate. */
3513 comp_code = swap_tree_comparison (TREE_CODE (cond));
3514 val = TREE_OPERAND (cond, 0);
3518 /* The comparison is of the form NAME COMP VAL, so the
3519 comparison code remains unchanged. */
3520 comp_code = TREE_CODE (cond);
3521 val = TREE_OPERAND (cond, 1);
3524 /* Invert the comparison code as necessary. */
3526 comp_code = invert_tree_comparison (comp_code, 0);
3528 /* VRP does not handle float types. */
3529 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)))
3532 /* Do not register always-false predicates.
3533 FIXME: this works around a limitation in fold() when dealing with
3534 enumerations. Given 'enum { N1, N2 } x;', fold will not
3535 fold 'if (x > N2)' to 'if (0)'. */
3536 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
3537 && INTEGRAL_TYPE_P (TREE_TYPE (val)))
3539 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
3540 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
3542 if (comp_code == GT_EXPR
3544 || compare_values (val, max) == 0))
3547 if (comp_code == LT_EXPR
3549 || compare_values (val, min) == 0))
3553 *code_p = comp_code;
3558 /* OP is an operand of a truth value expression which is known to have
3559 a particular value. Register any asserts for OP and for any
3560 operands in OP's defining statement.
3562 If CODE is EQ_EXPR, then we want to register OP is zero (false),
3563 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
3566 register_edge_assert_for_1 (tree op, enum tree_code code,
3567 edge e, block_stmt_iterator bsi)
3569 bool retval = false;
3570 tree op_def, rhs, val;
3572 /* We only care about SSA_NAMEs. */
3573 if (TREE_CODE (op) != SSA_NAME)
3576 /* We know that OP will have a zero or nonzero value. If OP is used
3577 more than once go ahead and register an assert for OP.
3579 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
3580 it will always be set for OP (because OP is used in a COND_EXPR in
3582 if (!has_single_use (op))
3584 val = build_int_cst (TREE_TYPE (op), 0);
3585 register_new_assert_for (op, code, val, NULL, e, bsi);
3589 /* Now look at how OP is set. If it's set from a comparison,
3590 a truth operation or some bit operations, then we may be able
3591 to register information about the operands of that assignment. */
3592 op_def = SSA_NAME_DEF_STMT (op);
3593 if (TREE_CODE (op_def) != GIMPLE_MODIFY_STMT)
3596 rhs = GIMPLE_STMT_OPERAND (op_def, 1);
3598 if (COMPARISON_CLASS_P (rhs))
3600 bool invert = (code == EQ_EXPR ? true : false);
3601 tree op0 = TREE_OPERAND (rhs, 0);
3602 tree op1 = TREE_OPERAND (rhs, 1);
3604 /* Conditionally register an assert for each SSA_NAME in the
3606 if (TREE_CODE (op0) == SSA_NAME
3607 && !has_single_use (op0)
3608 && extract_code_and_val_from_cond (op0, rhs,
3609 invert, &code, &val))
3611 register_new_assert_for (op0, code, val, NULL, e, bsi);
3615 /* Similarly for the second operand of the comparison. */
3616 if (TREE_CODE (op1) == SSA_NAME
3617 && !has_single_use (op1)
3618 && extract_code_and_val_from_cond (op1, rhs,
3619 invert, &code, &val))
3621 register_new_assert_for (op1, code, val, NULL, e, bsi);
3625 else if ((code == NE_EXPR
3626 && (TREE_CODE (rhs) == TRUTH_AND_EXPR
3627 || TREE_CODE (rhs) == BIT_AND_EXPR))
3629 && (TREE_CODE (rhs) == TRUTH_OR_EXPR
3630 || TREE_CODE (rhs) == BIT_IOR_EXPR)))
3632 /* Recurse on each operand. */
3633 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3635 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 1),
3638 else if (TREE_CODE (rhs) == TRUTH_NOT_EXPR)
3640 /* Recurse, flipping CODE. */
3641 code = invert_tree_comparison (code, false);
3642 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3645 else if (TREE_CODE (rhs) == SSA_NAME)
3647 /* Recurse through the copy. */
3648 retval |= register_edge_assert_for_1 (rhs, code, e, bsi);
3650 else if (TREE_CODE (rhs) == NOP_EXPR
3651 || TREE_CODE (rhs) == CONVERT_EXPR
3652 || TREE_CODE (rhs) == NON_LVALUE_EXPR)
3654 /* Recurse through the type conversion. */
3655 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3662 /* Try to register an edge assertion for SSA name NAME on edge E for
3663 the condition COND contributing to the conditional jump pointed to by SI.
3664 Return true if an assertion for NAME could be registered. */
3667 register_edge_assert_for (tree name, edge e, block_stmt_iterator si, tree cond)
3670 enum tree_code comp_code;
3671 bool retval = false;
3672 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
3674 /* Do not attempt to infer anything in names that flow through
3676 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
3679 if (!extract_code_and_val_from_cond (name, cond, is_else_edge,
3683 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
3684 reachable from E. */
3685 if (TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
3687 register_new_assert_for (name, comp_code, val, NULL, e, si);
3691 /* If COND is effectively an equality test of an SSA_NAME against
3692 the value zero or one, then we may be able to assert values
3693 for SSA_NAMEs which flow into COND. */
3695 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
3696 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
3697 have nonzero value. */
3698 if (((comp_code == EQ_EXPR && integer_onep (val))
3699 || (comp_code == NE_EXPR && integer_zerop (val))))
3701 tree def_stmt = SSA_NAME_DEF_STMT (name);
3703 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3704 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_AND_EXPR
3705 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_AND_EXPR))
3707 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3708 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3709 retval |= register_edge_assert_for_1 (op0, NE_EXPR, e, si);
3710 retval |= register_edge_assert_for_1 (op1, NE_EXPR, e, si);
3714 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
3715 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
3717 if (((comp_code == EQ_EXPR && integer_zerop (val))
3718 || (comp_code == NE_EXPR && integer_onep (val))))
3720 tree def_stmt = SSA_NAME_DEF_STMT (name);
3722 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3723 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_OR_EXPR
3724 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_IOR_EXPR))
3726 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3727 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3728 retval |= register_edge_assert_for_1 (op0, EQ_EXPR, e, si);
3729 retval |= register_edge_assert_for_1 (op1, EQ_EXPR, e, si);
3737 static bool find_assert_locations (basic_block bb);
3739 /* Determine whether the outgoing edges of BB should receive an
3740 ASSERT_EXPR for each of the operands of BB's LAST statement.
3741 The last statement of BB must be a COND_EXPR.
3743 If any of the sub-graphs rooted at BB have an interesting use of
3744 the predicate operands, an assert location node is added to the
3745 list of assertions for the corresponding operands. */
3748 find_conditional_asserts (basic_block bb, tree last)
3751 block_stmt_iterator bsi;
3757 need_assert = false;
3758 bsi = bsi_for_stmt (last);
3760 /* Look for uses of the operands in each of the sub-graphs
3761 rooted at BB. We need to check each of the outgoing edges
3762 separately, so that we know what kind of ASSERT_EXPR to
3764 FOR_EACH_EDGE (e, ei, bb->succs)
3769 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
3770 Otherwise, when we finish traversing each of the sub-graphs, we
3771 won't know whether the variables were found in the sub-graphs or
3772 if they had been found in a block upstream from BB.
3774 This is actually a bad idea is some cases, particularly jump
3775 threading. Consider a CFG like the following:
3785 Assume that one or more operands in the conditional at the
3786 end of block 0 are used in a conditional in block 2, but not
3787 anywhere in block 1. In this case we will not insert any
3788 assert statements in block 1, which may cause us to miss
3789 opportunities to optimize, particularly for jump threading. */
3790 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3791 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3793 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3794 to determine if any of the operands in the conditional
3795 predicate are used. */
3797 need_assert |= find_assert_locations (e->dest);
3799 /* Register the necessary assertions for each operand in the
3800 conditional predicate. */
3801 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3802 need_assert |= register_edge_assert_for (op, e, bsi,
3803 COND_EXPR_COND (last));
3806 /* Finally, indicate that we have found the operands in the
3808 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3809 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3814 /* Compare two case labels sorting first by the destination label uid
3815 and then by the case value. */
3818 compare_case_labels (const void *p1, const void *p2)
3820 tree case1 = *(tree *)p1;
3821 tree case2 = *(tree *)p2;
3822 unsigned int uid1 = DECL_UID (CASE_LABEL (case1));
3823 unsigned int uid2 = DECL_UID (CASE_LABEL (case2));
3827 else if (uid1 == uid2)
3829 /* Make sure the default label is first in a group. */
3830 if (!CASE_LOW (case1))
3832 else if (!CASE_LOW (case2))
3835 return tree_int_cst_compare (CASE_LOW (case1), CASE_LOW (case2));
3841 /* Determine whether the outgoing edges of BB should receive an
3842 ASSERT_EXPR for each of the operands of BB's LAST statement.
3843 The last statement of BB must be a SWITCH_EXPR.
3845 If any of the sub-graphs rooted at BB have an interesting use of
3846 the predicate operands, an assert location node is added to the
3847 list of assertions for the corresponding operands. */
3850 find_switch_asserts (basic_block bb, tree last)
3853 block_stmt_iterator bsi;
3856 tree vec = SWITCH_LABELS (last), vec2;
3857 size_t n = TREE_VEC_LENGTH (vec);
3860 need_assert = false;
3861 bsi = bsi_for_stmt (last);
3862 op = TREE_OPERAND (last, 0);
3863 if (TREE_CODE (op) != SSA_NAME)
3866 /* Build a vector of case labels sorted by destination label. */
3867 vec2 = make_tree_vec (n);
3868 for (idx = 0; idx < n; ++idx)
3869 TREE_VEC_ELT (vec2, idx) = TREE_VEC_ELT (vec, idx);
3870 qsort (&TREE_VEC_ELT (vec2, 0), n, sizeof (tree), compare_case_labels);
3872 for (idx = 0; idx < n; ++idx)
3875 tree cl = TREE_VEC_ELT (vec2, idx);
3877 min = CASE_LOW (cl);
3878 max = CASE_HIGH (cl);
3880 /* If there are multiple case labels with the same destination
3881 we need to combine them to a single value range for the edge. */
3883 && CASE_LABEL (cl) == CASE_LABEL (TREE_VEC_ELT (vec2, idx + 1)))
3885 /* Skip labels until the last of the group. */
3889 && CASE_LABEL (cl) == CASE_LABEL (TREE_VEC_ELT (vec2, idx)));
3892 /* Pick up the maximum of the case label range. */
3893 if (CASE_HIGH (TREE_VEC_ELT (vec2, idx)))
3894 max = CASE_HIGH (TREE_VEC_ELT (vec2, idx));
3896 max = CASE_LOW (TREE_VEC_ELT (vec2, idx));
3899 /* Nothing to do if the range includes the default label until we
3900 can register anti-ranges. */
3901 if (min == NULL_TREE)
3904 /* Find the edge to register the assert expr on. */
3905 e = find_edge (bb, label_to_block (CASE_LABEL (cl)));
3907 /* Remove the SWITCH_EXPR operand from the FOUND_IN_SUBGRAPH bitmap.
3908 Otherwise, when we finish traversing each of the sub-graphs, we
3909 won't know whether the variables were found in the sub-graphs or
3910 if they had been found in a block upstream from BB. */
3911 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3913 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3914 to determine if any of the operands in the conditional
3915 predicate are used. */
3917 need_assert |= find_assert_locations (e->dest);
3919 /* Register the necessary assertions for the operand in the
3921 cond = build2 (max ? GE_EXPR : EQ_EXPR, boolean_type_node,
3922 op, fold_convert (TREE_TYPE (op), min));
3923 need_assert |= register_edge_assert_for (op, e, bsi, cond);
3926 cond = build2 (LE_EXPR, boolean_type_node,
3927 op, fold_convert (TREE_TYPE (op), max));
3928 need_assert |= register_edge_assert_for (op, e, bsi, cond);
3932 /* Finally, indicate that we have found the operand in the
3934 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3940 /* Traverse all the statements in block BB looking for statements that
3941 may generate useful assertions for the SSA names in their operand.
3942 If a statement produces a useful assertion A for name N_i, then the
3943 list of assertions already generated for N_i is scanned to
3944 determine if A is actually needed.
3946 If N_i already had the assertion A at a location dominating the
3947 current location, then nothing needs to be done. Otherwise, the
3948 new location for A is recorded instead.
3950 1- For every statement S in BB, all the variables used by S are
3951 added to bitmap FOUND_IN_SUBGRAPH.
3953 2- If statement S uses an operand N in a way that exposes a known
3954 value range for N, then if N was not already generated by an
3955 ASSERT_EXPR, create a new assert location for N. For instance,
3956 if N is a pointer and the statement dereferences it, we can
3957 assume that N is not NULL.
3959 3- COND_EXPRs are a special case of #2. We can derive range
3960 information from the predicate but need to insert different
3961 ASSERT_EXPRs for each of the sub-graphs rooted at the
3962 conditional block. If the last statement of BB is a conditional
3963 expression of the form 'X op Y', then
3965 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
3967 b) If the conditional is the only entry point to the sub-graph
3968 corresponding to the THEN_CLAUSE, recurse into it. On
3969 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
3970 an ASSERT_EXPR is added for the corresponding variable.
3972 c) Repeat step (b) on the ELSE_CLAUSE.
3974 d) Mark X and Y in FOUND_IN_SUBGRAPH.
3983 In this case, an assertion on the THEN clause is useful to
3984 determine that 'a' is always 9 on that edge. However, an assertion
3985 on the ELSE clause would be unnecessary.
3987 4- If BB does not end in a conditional expression, then we recurse
3988 into BB's dominator children.
3990 At the end of the recursive traversal, every SSA name will have a
3991 list of locations where ASSERT_EXPRs should be added. When a new
3992 location for name N is found, it is registered by calling
3993 register_new_assert_for. That function keeps track of all the
3994 registered assertions to prevent adding unnecessary assertions.
3995 For instance, if a pointer P_4 is dereferenced more than once in a
3996 dominator tree, only the location dominating all the dereference of
3997 P_4 will receive an ASSERT_EXPR.
3999 If this function returns true, then it means that there are names
4000 for which we need to generate ASSERT_EXPRs. Those assertions are
4001 inserted by process_assert_insertions. */
4004 find_assert_locations (basic_block bb)
4006 block_stmt_iterator si;
4011 if (TEST_BIT (blocks_visited, bb->index))
4014 SET_BIT (blocks_visited, bb->index);
4016 need_assert = false;
4018 /* Traverse all PHI nodes in BB marking used operands. */
4019 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4021 use_operand_p arg_p;
4024 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
4026 tree arg = USE_FROM_PTR (arg_p);
4027 if (TREE_CODE (arg) == SSA_NAME)
4029 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
4030 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
4035 /* Traverse all the statements in BB marking used names and looking
4036 for statements that may infer assertions for their used operands. */
4038 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
4043 stmt = bsi_stmt (si);
4045 /* See if we can derive an assertion for any of STMT's operands. */
4046 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
4049 enum tree_code comp_code;
4051 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
4052 the sub-graph of a conditional block, when we return from
4053 this recursive walk, our parent will use the
4054 FOUND_IN_SUBGRAPH bitset to determine if one of the
4055 operands it was looking for was present in the sub-graph. */
4056 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
4058 /* If OP is used in such a way that we can infer a value
4059 range for it, and we don't find a previous assertion for
4060 it, create a new assertion location node for OP. */
4061 if (infer_value_range (stmt, op, &comp_code, &value))
4063 /* If we are able to infer a nonzero value range for OP,
4064 then walk backwards through the use-def chain to see if OP
4065 was set via a typecast.
4067 If so, then we can also infer a nonzero value range
4068 for the operand of the NOP_EXPR. */
4069 if (comp_code == NE_EXPR && integer_zerop (value))
4072 tree def_stmt = SSA_NAME_DEF_STMT (t);
4074 while (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
4076 (GIMPLE_STMT_OPERAND (def_stmt, 1)) == NOP_EXPR
4078 (TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1),
4081 (TREE_TYPE (TREE_OPERAND
4082 (GIMPLE_STMT_OPERAND (def_stmt,
4085 t = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
4086 def_stmt = SSA_NAME_DEF_STMT (t);
4088 /* Note we want to register the assert for the
4089 operand of the NOP_EXPR after SI, not after the
4091 if (! has_single_use (t))
4093 register_new_assert_for (t, comp_code, value,
4100 /* If OP is used only once, namely in this STMT, don't
4101 bother creating an ASSERT_EXPR for it. Such an
4102 ASSERT_EXPR would do nothing but increase compile time. */
4103 if (!has_single_use (op))
4105 register_new_assert_for (op, comp_code, value, bb, NULL, si);
4111 /* Remember the last statement of the block. */
4115 /* If BB's last statement is a conditional expression
4116 involving integer operands, recurse into each of the sub-graphs
4117 rooted at BB to determine if we need to add ASSERT_EXPRs. */
4119 && TREE_CODE (last) == COND_EXPR
4120 && !fp_predicate (COND_EXPR_COND (last))
4121 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
4122 need_assert |= find_conditional_asserts (bb, last);
4125 && TREE_CODE (last) == SWITCH_EXPR
4126 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
4127 need_assert |= find_switch_asserts (bb, last);
4129 /* Recurse into the dominator children of BB. */
4130 for (son = first_dom_son (CDI_DOMINATORS, bb);
4132 son = next_dom_son (CDI_DOMINATORS, son))
4133 need_assert |= find_assert_locations (son);
4139 /* Create an ASSERT_EXPR for NAME and insert it in the location
4140 indicated by LOC. Return true if we made any edge insertions. */
4143 process_assert_insertions_for (tree name, assert_locus_t loc)
4145 /* Build the comparison expression NAME_i COMP_CODE VAL. */
4146 tree stmt, cond, assert_expr;
4150 cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
4151 assert_expr = build_assert_expr_for (cond, name);
4155 /* We have been asked to insert the assertion on an edge. This
4156 is used only by COND_EXPR and SWITCH_EXPR assertions. */
4157 #if defined ENABLE_CHECKING
4158 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
4159 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
4162 bsi_insert_on_edge (loc->e, assert_expr);
4166 /* Otherwise, we can insert right after LOC->SI iff the
4167 statement must not be the last statement in the block. */
4168 stmt = bsi_stmt (loc->si);
4169 if (!stmt_ends_bb_p (stmt))
4171 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
4175 /* If STMT must be the last statement in BB, we can only insert new
4176 assertions on the non-abnormal edge out of BB. Note that since
4177 STMT is not control flow, there may only be one non-abnormal edge
4179 FOR_EACH_EDGE (e, ei, loc->bb->succs)
4180 if (!(e->flags & EDGE_ABNORMAL))
4182 bsi_insert_on_edge (e, assert_expr);
4190 /* Process all the insertions registered for every name N_i registered
4191 in NEED_ASSERT_FOR. The list of assertions to be inserted are
4192 found in ASSERTS_FOR[i]. */
4195 process_assert_insertions (void)
4199 bool update_edges_p = false;
4200 int num_asserts = 0;
4202 if (dump_file && (dump_flags & TDF_DETAILS))
4203 dump_all_asserts (dump_file);
4205 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
4207 assert_locus_t loc = asserts_for[i];
4212 assert_locus_t next = loc->next;
4213 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
4221 bsi_commit_edge_inserts ();
4223 if (dump_file && (dump_flags & TDF_STATS))
4224 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
4229 /* Traverse the flowgraph looking for conditional jumps to insert range
4230 expressions. These range expressions are meant to provide information
4231 to optimizations that need to reason in terms of value ranges. They
4232 will not be expanded into RTL. For instance, given:
4241 this pass will transform the code into:
4247 x = ASSERT_EXPR <x, x < y>
4252 y = ASSERT_EXPR <y, x <= y>
4256 The idea is that once copy and constant propagation have run, other
4257 optimizations will be able to determine what ranges of values can 'x'
4258 take in different paths of the code, simply by checking the reaching
4259 definition of 'x'. */
4262 insert_range_assertions (void)
4268 found_in_subgraph = sbitmap_alloc (num_ssa_names);
4269 sbitmap_zero (found_in_subgraph);
4271 blocks_visited = sbitmap_alloc (last_basic_block);
4272 sbitmap_zero (blocks_visited);
4274 need_assert_for = BITMAP_ALLOC (NULL);
4275 asserts_for = XCNEWVEC (assert_locus_t, num_ssa_names);
4277 calculate_dominance_info (CDI_DOMINATORS);
4279 update_ssa_p = false;
4280 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
4281 if (find_assert_locations (e->dest))
4282 update_ssa_p = true;
4286 process_assert_insertions ();
4287 update_ssa (TODO_update_ssa_no_phi);
4290 if (dump_file && (dump_flags & TDF_DETAILS))
4292 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
4293 dump_function_to_file (current_function_decl, dump_file, dump_flags);
4296 sbitmap_free (found_in_subgraph);
4298 BITMAP_FREE (need_assert_for);
4301 /* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays
4302 and "struct" hacks. If VRP can determine that the
4303 array subscript is a constant, check if it is outside valid
4304 range. If the array subscript is a RANGE, warn if it is
4305 non-overlapping with valid range.
4306 IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */
4309 check_array_ref (tree ref, location_t* locus, bool ignore_off_by_one)
4311 value_range_t* vr = NULL;
4312 tree low_sub, up_sub;
4313 tree low_bound, up_bound = array_ref_up_bound (ref);
4315 low_sub = up_sub = TREE_OPERAND (ref, 1);
4317 if (!up_bound || !locus || TREE_NO_WARNING (ref)
4318 || TREE_CODE (up_bound) != INTEGER_CST
4319 /* Can not check flexible arrays. */
4320 || (TYPE_SIZE (TREE_TYPE (ref)) == NULL_TREE
4321 && TYPE_DOMAIN (TREE_TYPE (ref)) != NULL_TREE
4322 && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (ref))) == NULL_TREE)
4323 /* Accesses after the end of arrays of size 0 (gcc
4324 extension) and 1 are likely intentional ("struct
4326 || compare_tree_int (up_bound, 1) <= 0)
4329 low_bound = array_ref_low_bound (ref);
4331 if (TREE_CODE (low_sub) == SSA_NAME)
4333 vr = get_value_range (low_sub);
4334 if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
4336 low_sub = vr->type == VR_RANGE ? vr->max : vr->min;
4337 up_sub = vr->type == VR_RANGE ? vr->min : vr->max;
4341 if (vr && vr->type == VR_ANTI_RANGE)
4343 if (TREE_CODE (up_sub) == INTEGER_CST
4344 && tree_int_cst_lt (up_bound, up_sub)
4345 && TREE_CODE (low_sub) == INTEGER_CST
4346 && tree_int_cst_lt (low_sub, low_bound))
4348 warning (OPT_Warray_bounds,
4349 "%Harray subscript is outside array bounds", locus);
4350 TREE_NO_WARNING (ref) = 1;
4353 else if (TREE_CODE (up_sub) == INTEGER_CST
4354 && tree_int_cst_lt (up_bound, up_sub)
4355 && !tree_int_cst_equal (up_bound, up_sub)
4356 && (!ignore_off_by_one
4357 || !tree_int_cst_equal (int_const_binop (PLUS_EXPR,
4363 warning (OPT_Warray_bounds, "%Harray subscript is above array bounds",
4365 TREE_NO_WARNING (ref) = 1;
4367 else if (TREE_CODE (low_sub) == INTEGER_CST
4368 && tree_int_cst_lt (low_sub, low_bound))
4370 warning (OPT_Warray_bounds, "%Harray subscript is below array bounds",
4372 TREE_NO_WARNING (ref) = 1;
4376 /* Searches if the expr T, located at LOCATION computes
4377 address of an ARRAY_REF, and call check_array_ref on it. */
4380 search_for_addr_array(tree t, location_t* location)
4382 while (TREE_CODE (t) == SSA_NAME)
4384 t = SSA_NAME_DEF_STMT (t);
4385 if (TREE_CODE (t) != GIMPLE_MODIFY_STMT)
4387 t = GIMPLE_STMT_OPERAND (t, 1);
4391 /* We are only interested in addresses of ARRAY_REF's. */
4392 if (TREE_CODE (t) != ADDR_EXPR)
4395 /* Check each ARRAY_REFs in the reference chain. */
4398 if (TREE_CODE (t) == ARRAY_REF)
4399 check_array_ref (t, location, true /*ignore_off_by_one*/);
4401 t = TREE_OPERAND(t,0);
4403 while (handled_component_p (t));
4406 /* walk_tree() callback that checks if *TP is
4407 an ARRAY_REF inside an ADDR_EXPR (in which an array
4408 subscript one outside the valid range is allowed). Call
4409 check_array_ref for each ARRAY_REF found. The location is
4413 check_array_bounds (tree *tp, int *walk_subtree, void *data)
4416 tree stmt = (tree)data;
4417 location_t *location = EXPR_LOCUS (stmt);
4419 *walk_subtree = TRUE;
4421 if (TREE_CODE (t) == ARRAY_REF)
4422 check_array_ref (t, location, false /*ignore_off_by_one*/);
4424 if (TREE_CODE (t) == INDIRECT_REF
4425 || (TREE_CODE (t) == RETURN_EXPR && TREE_OPERAND (t, 0)))
4426 search_for_addr_array (TREE_OPERAND (t, 0), location);
4427 else if (TREE_CODE (t) == CALL_EXPR)
4430 call_expr_arg_iterator iter;
4432 FOR_EACH_CALL_EXPR_ARG (arg, iter, t)
4433 search_for_addr_array (arg, location);
4436 if (TREE_CODE (t) == ADDR_EXPR)
4437 *walk_subtree = FALSE;
4442 /* Walk over all statements of all reachable BBs and call check_array_bounds
4446 check_all_array_refs (void)
4449 block_stmt_iterator si;
4453 /* Skip bb's that are clearly unreachable. */
4454 if (single_pred_p (bb))
4456 basic_block pred_bb = EDGE_PRED (bb, 0)->src;
4457 tree ls = NULL_TREE;
4459 if (!bsi_end_p (bsi_last (pred_bb)))
4460 ls = bsi_stmt (bsi_last (pred_bb));
4462 if (ls && TREE_CODE (ls) == COND_EXPR
4463 && ((COND_EXPR_COND (ls) == boolean_false_node
4464 && (EDGE_PRED (bb, 0)->flags & EDGE_TRUE_VALUE))
4465 || (COND_EXPR_COND (ls) == boolean_true_node
4466 && (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE))))
4469 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
4470 walk_tree (bsi_stmt_ptr (si), check_array_bounds,
4471 bsi_stmt (si), NULL);
4475 /* Convert range assertion expressions into the implied copies and
4476 copy propagate away the copies. Doing the trivial copy propagation
4477 here avoids the need to run the full copy propagation pass after
4480 FIXME, this will eventually lead to copy propagation removing the
4481 names that had useful range information attached to them. For
4482 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
4483 then N_i will have the range [3, +INF].
4485 However, by converting the assertion into the implied copy
4486 operation N_i = N_j, we will then copy-propagate N_j into the uses
4487 of N_i and lose the range information. We may want to hold on to
4488 ASSERT_EXPRs a little while longer as the ranges could be used in
4489 things like jump threading.
4491 The problem with keeping ASSERT_EXPRs around is that passes after
4492 VRP need to handle them appropriately.
4494 Another approach would be to make the range information a first
4495 class property of the SSA_NAME so that it can be queried from
4496 any pass. This is made somewhat more complex by the need for
4497 multiple ranges to be associated with one SSA_NAME. */
4500 remove_range_assertions (void)
4503 block_stmt_iterator si;
4505 /* Note that the BSI iterator bump happens at the bottom of the
4506 loop and no bump is necessary if we're removing the statement
4507 referenced by the current BSI. */
4509 for (si = bsi_start (bb); !bsi_end_p (si);)
4511 tree stmt = bsi_stmt (si);
4514 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
4515 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ASSERT_EXPR)
4517 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1), var;
4518 tree cond = fold (ASSERT_EXPR_COND (rhs));
4519 use_operand_p use_p;
4520 imm_use_iterator iter;
4522 gcc_assert (cond != boolean_false_node);
4524 /* Propagate the RHS into every use of the LHS. */
4525 var = ASSERT_EXPR_VAR (rhs);
4526 FOR_EACH_IMM_USE_STMT (use_stmt, iter,
4527 GIMPLE_STMT_OPERAND (stmt, 0))
4528 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
4530 SET_USE (use_p, var);
4531 gcc_assert (TREE_CODE (var) == SSA_NAME);
4534 /* And finally, remove the copy, it is not needed. */
4535 bsi_remove (&si, true);
4536 release_defs (stmt);
4542 sbitmap_free (blocks_visited);
4546 /* Return true if STMT is interesting for VRP. */
4549 stmt_interesting_for_vrp (tree stmt)
4551 if (TREE_CODE (stmt) == PHI_NODE
4552 && is_gimple_reg (PHI_RESULT (stmt))
4553 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
4554 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
4556 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4558 tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
4559 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4561 /* In general, assignments with virtual operands are not useful
4562 for deriving ranges, with the obvious exception of calls to
4563 builtin functions. */
4564 if (TREE_CODE (lhs) == SSA_NAME
4565 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
4566 || POINTER_TYPE_P (TREE_TYPE (lhs)))
4567 && ((TREE_CODE (rhs) == CALL_EXPR
4568 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
4569 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs), 0))
4570 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
4571 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)))
4574 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
4581 /* Initialize local data structures for VRP. */
4584 vrp_initialize (void)
4588 vr_value = XCNEWVEC (value_range_t *, num_ssa_names);
4589 vr_phi_edge_counts = XCNEWVEC (int, num_ssa_names);
4593 block_stmt_iterator si;
4596 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4598 if (!stmt_interesting_for_vrp (phi))
4600 tree lhs = PHI_RESULT (phi);
4601 set_value_range_to_varying (get_value_range (lhs));
4602 DONT_SIMULATE_AGAIN (phi) = true;
4605 DONT_SIMULATE_AGAIN (phi) = false;
4608 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
4610 tree stmt = bsi_stmt (si);
4612 if (!stmt_interesting_for_vrp (stmt))
4616 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
4617 set_value_range_to_varying (get_value_range (def));
4618 DONT_SIMULATE_AGAIN (stmt) = true;
4622 DONT_SIMULATE_AGAIN (stmt) = false;
4629 /* Visit assignment STMT. If it produces an interesting range, record
4630 the SSA name in *OUTPUT_P. */
4632 static enum ssa_prop_result
4633 vrp_visit_assignment (tree stmt, tree *output_p)
4638 lhs = GIMPLE_STMT_OPERAND (stmt, 0);
4639 rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4641 /* We only keep track of ranges in integral and pointer types. */
4642 if (TREE_CODE (lhs) == SSA_NAME
4643 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
4644 /* It is valid to have NULL MIN/MAX values on a type. See
4645 build_range_type. */
4646 && TYPE_MIN_VALUE (TREE_TYPE (lhs))
4647 && TYPE_MAX_VALUE (TREE_TYPE (lhs)))
4648 || POINTER_TYPE_P (TREE_TYPE (lhs))))
4651 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
4653 extract_range_from_expr (&new_vr, rhs);
4655 /* If STMT is inside a loop, we may be able to know something
4656 else about the range of LHS by examining scalar evolution
4658 if (current_loops && (l = loop_containing_stmt (stmt)))
4659 adjust_range_with_scev (&new_vr, l, stmt, lhs);
4661 if (update_value_range (lhs, &new_vr))
4665 if (dump_file && (dump_flags & TDF_DETAILS))
4667 fprintf (dump_file, "Found new range for ");
4668 print_generic_expr (dump_file, lhs, 0);
4669 fprintf (dump_file, ": ");
4670 dump_value_range (dump_file, &new_vr);
4671 fprintf (dump_file, "\n\n");
4674 if (new_vr.type == VR_VARYING)
4675 return SSA_PROP_VARYING;
4677 return SSA_PROP_INTERESTING;
4680 return SSA_PROP_NOT_INTERESTING;
4683 /* Every other statement produces no useful ranges. */
4684 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
4685 set_value_range_to_varying (get_value_range (def));
4687 return SSA_PROP_VARYING;
4690 /* Helper that gets the value range of the SSA_NAME with version I
4691 or a symbolic range containing the SSA_NAME only if the value range
4692 is varying or undefined. */
4694 static inline value_range_t
4695 get_vr_for_comparison (int i)
4697 value_range_t vr = *(vr_value[i]);
4699 /* If name N_i does not have a valid range, use N_i as its own
4700 range. This allows us to compare against names that may
4701 have N_i in their ranges. */
4702 if (vr.type == VR_VARYING || vr.type == VR_UNDEFINED)
4705 vr.min = ssa_name (i);
4706 vr.max = ssa_name (i);
4712 /* Compare all the value ranges for names equivalent to VAR with VAL
4713 using comparison code COMP. Return the same value returned by
4714 compare_range_with_value, including the setting of
4715 *STRICT_OVERFLOW_P. */
4718 compare_name_with_value (enum tree_code comp, tree var, tree val,
4719 bool *strict_overflow_p)
4725 int used_strict_overflow;
4727 value_range_t equiv_vr;
4729 /* Get the set of equivalences for VAR. */
4730 e = get_value_range (var)->equiv;
4732 /* Start at -1. Set it to 0 if we do a comparison without relying
4733 on overflow, or 1 if all comparisons rely on overflow. */
4734 used_strict_overflow = -1;
4736 /* Compare vars' value range with val. */
4737 equiv_vr = get_vr_for_comparison (SSA_NAME_VERSION (var));
4739 retval = compare_range_with_value (comp, &equiv_vr, val, &sop);
4741 used_strict_overflow = sop ? 1 : 0;
4743 /* If the equiv set is empty we have done all work we need to do. */
4747 && used_strict_overflow > 0)
4748 *strict_overflow_p = true;
4752 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
4754 equiv_vr = get_vr_for_comparison (i);
4756 t = compare_range_with_value (comp, &equiv_vr, val, &sop);
4759 /* If we get different answers from different members
4760 of the equivalence set this check must be in a dead
4761 code region. Folding it to a trap representation
4762 would be correct here. For now just return don't-know. */
4772 used_strict_overflow = 0;
4773 else if (used_strict_overflow < 0)
4774 used_strict_overflow = 1;
4779 && used_strict_overflow > 0)
4780 *strict_overflow_p = true;
4786 /* Given a comparison code COMP and names N1 and N2, compare all the
4787 ranges equivalent to N1 against all the ranges equivalent to N2
4788 to determine the value of N1 COMP N2. Return the same value
4789 returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate
4790 whether we relied on an overflow infinity in the comparison. */
4794 compare_names (enum tree_code comp, tree n1, tree n2,
4795 bool *strict_overflow_p)
4799 bitmap_iterator bi1, bi2;
4801 int used_strict_overflow;
4802 static bitmap_obstack *s_obstack = NULL;
4803 static bitmap s_e1 = NULL, s_e2 = NULL;
4805 /* Compare the ranges of every name equivalent to N1 against the
4806 ranges of every name equivalent to N2. */
4807 e1 = get_value_range (n1)->equiv;
4808 e2 = get_value_range (n2)->equiv;
4810 /* Use the fake bitmaps if e1 or e2 are not available. */
4811 if (s_obstack == NULL)
4813 s_obstack = XNEW (bitmap_obstack);
4814 bitmap_obstack_initialize (s_obstack);
4815 s_e1 = BITMAP_ALLOC (s_obstack);
4816 s_e2 = BITMAP_ALLOC (s_obstack);
4823 /* Add N1 and N2 to their own set of equivalences to avoid
4824 duplicating the body of the loop just to check N1 and N2
4826 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
4827 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
4829 /* If the equivalence sets have a common intersection, then the two
4830 names can be compared without checking their ranges. */
4831 if (bitmap_intersect_p (e1, e2))
4833 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4834 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4836 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
4838 : boolean_false_node;
4841 /* Start at -1. Set it to 0 if we do a comparison without relying
4842 on overflow, or 1 if all comparisons rely on overflow. */
4843 used_strict_overflow = -1;
4845 /* Otherwise, compare all the equivalent ranges. First, add N1 and
4846 N2 to their own set of equivalences to avoid duplicating the body
4847 of the loop just to check N1 and N2 ranges. */
4848 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
4850 value_range_t vr1 = get_vr_for_comparison (i1);
4852 t = retval = NULL_TREE;
4853 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
4857 value_range_t vr2 = get_vr_for_comparison (i2);
4859 t = compare_ranges (comp, &vr1, &vr2, &sop);
4862 /* If we get different answers from different members
4863 of the equivalence set this check must be in a dead
4864 code region. Folding it to a trap representation
4865 would be correct here. For now just return don't-know. */
4869 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4870 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4876 used_strict_overflow = 0;
4877 else if (used_strict_overflow < 0)
4878 used_strict_overflow = 1;
4884 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4885 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4886 if (used_strict_overflow > 0)
4887 *strict_overflow_p = true;
4892 /* None of the equivalent ranges are useful in computing this
4894 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4895 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4900 /* Given a conditional predicate COND, try to determine if COND yields
4901 true or false based on the value ranges of its operands. Return
4902 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
4903 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
4904 NULL if the conditional cannot be evaluated at compile time.
4906 If USE_EQUIV_P is true, the ranges of all the names equivalent with
4907 the operands in COND are used when trying to compute its value.
4908 This is only used during final substitution. During propagation,
4909 we only check the range of each variable and not its equivalents.
4911 Set *STRICT_OVERFLOW_P to indicate whether we relied on an overflow
4912 infinity to produce the result. */
4915 vrp_evaluate_conditional_warnv (tree cond, bool use_equiv_p,
4916 bool *strict_overflow_p)
4918 gcc_assert (TREE_CODE (cond) == SSA_NAME
4919 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
4921 if (TREE_CODE (cond) == SSA_NAME)
4927 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node,
4931 value_range_t *vr = get_value_range (cond);
4932 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node,
4936 /* If COND has a known boolean range, return it. */
4940 /* Otherwise, if COND has a symbolic range of exactly one value,
4942 vr = get_value_range (cond);
4943 if (vr->type == VR_RANGE && vr->min == vr->max)
4948 tree op0 = TREE_OPERAND (cond, 0);
4949 tree op1 = TREE_OPERAND (cond, 1);
4951 /* We only deal with integral and pointer types. */
4952 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
4953 && !POINTER_TYPE_P (TREE_TYPE (op0)))
4958 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
4959 return compare_names (TREE_CODE (cond), op0, op1,
4961 else if (TREE_CODE (op0) == SSA_NAME)
4962 return compare_name_with_value (TREE_CODE (cond), op0, op1,
4964 else if (TREE_CODE (op1) == SSA_NAME)
4965 return (compare_name_with_value
4966 (swap_tree_comparison (TREE_CODE (cond)), op1, op0,
4967 strict_overflow_p));
4971 value_range_t *vr0, *vr1;
4973 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
4974 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
4977 return compare_ranges (TREE_CODE (cond), vr0, vr1,
4979 else if (vr0 && vr1 == NULL)
4980 return compare_range_with_value (TREE_CODE (cond), vr0, op1,
4982 else if (vr0 == NULL && vr1)
4983 return (compare_range_with_value
4984 (swap_tree_comparison (TREE_CODE (cond)), vr1, op0,
4985 strict_overflow_p));
4989 /* Anything else cannot be computed statically. */
4993 /* Given COND within STMT, try to simplify it based on value range
4994 information. Return NULL if the conditional can not be evaluated.
4995 The ranges of all the names equivalent with the operands in COND
4996 will be used when trying to compute the value. If the result is
4997 based on undefined signed overflow, issue a warning if
5001 vrp_evaluate_conditional (tree cond, tree stmt)
5007 ret = vrp_evaluate_conditional_warnv (cond, true, &sop);
5011 enum warn_strict_overflow_code wc;
5012 const char* warnmsg;
5014 if (is_gimple_min_invariant (ret))
5016 wc = WARN_STRICT_OVERFLOW_CONDITIONAL;
5017 warnmsg = G_("assuming signed overflow does not occur when "
5018 "simplifying conditional to constant");
5022 wc = WARN_STRICT_OVERFLOW_COMPARISON;
5023 warnmsg = G_("assuming signed overflow does not occur when "
5024 "simplifying conditional");
5027 if (issue_strict_overflow_warning (wc))
5031 if (!EXPR_HAS_LOCATION (stmt))
5032 locus = input_location;
5034 locus = EXPR_LOCATION (stmt);
5035 warning (OPT_Wstrict_overflow, "%H%s", &locus, warnmsg);
5043 /* Visit conditional statement STMT. If we can determine which edge
5044 will be taken out of STMT's basic block, record it in
5045 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
5046 SSA_PROP_VARYING. */
5048 static enum ssa_prop_result
5049 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
5054 *taken_edge_p = NULL;
5056 /* FIXME. Handle SWITCH_EXPRs. */
5057 if (TREE_CODE (stmt) == SWITCH_EXPR)
5058 return SSA_PROP_VARYING;
5060 cond = COND_EXPR_COND (stmt);
5062 if (dump_file && (dump_flags & TDF_DETAILS))
5067 fprintf (dump_file, "\nVisiting conditional with predicate: ");
5068 print_generic_expr (dump_file, cond, 0);
5069 fprintf (dump_file, "\nWith known ranges\n");
5071 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
5073 fprintf (dump_file, "\t");
5074 print_generic_expr (dump_file, use, 0);
5075 fprintf (dump_file, ": ");
5076 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
5079 fprintf (dump_file, "\n");
5082 /* Compute the value of the predicate COND by checking the known
5083 ranges of each of its operands.
5085 Note that we cannot evaluate all the equivalent ranges here
5086 because those ranges may not yet be final and with the current
5087 propagation strategy, we cannot determine when the value ranges
5088 of the names in the equivalence set have changed.
5090 For instance, given the following code fragment
5094 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
5098 Assume that on the first visit to i_14, i_5 has the temporary
5099 range [8, 8] because the second argument to the PHI function is
5100 not yet executable. We derive the range ~[0, 0] for i_14 and the
5101 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
5102 the first time, since i_14 is equivalent to the range [8, 8], we
5103 determine that the predicate is always false.
5105 On the next round of propagation, i_13 is determined to be
5106 VARYING, which causes i_5 to drop down to VARYING. So, another
5107 visit to i_14 is scheduled. In this second visit, we compute the
5108 exact same range and equivalence set for i_14, namely ~[0, 0] and
5109 { i_5 }. But we did not have the previous range for i_5
5110 registered, so vrp_visit_assignment thinks that the range for
5111 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
5112 is not visited again, which stops propagation from visiting
5113 statements in the THEN clause of that if().
5115 To properly fix this we would need to keep the previous range
5116 value for the names in the equivalence set. This way we would've
5117 discovered that from one visit to the other i_5 changed from
5118 range [8, 8] to VR_VARYING.
5120 However, fixing this apparent limitation may not be worth the
5121 additional checking. Testing on several code bases (GCC, DLV,
5122 MICO, TRAMP3D and SPEC2000) showed that doing this results in
5123 4 more predicates folded in SPEC. */
5125 val = vrp_evaluate_conditional_warnv (cond, false, &sop);
5129 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
5132 if (dump_file && (dump_flags & TDF_DETAILS))
5134 "\nIgnoring predicate evaluation because "
5135 "it assumes that signed overflow is undefined");
5140 if (dump_file && (dump_flags & TDF_DETAILS))
5142 fprintf (dump_file, "\nPredicate evaluates to: ");
5143 if (val == NULL_TREE)
5144 fprintf (dump_file, "DON'T KNOW\n");
5146 print_generic_stmt (dump_file, val, 0);
5149 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
5153 /* Evaluate statement STMT. If the statement produces a useful range,
5154 return SSA_PROP_INTERESTING and record the SSA name with the
5155 interesting range into *OUTPUT_P.
5157 If STMT is a conditional branch and we can determine its truth
5158 value, the taken edge is recorded in *TAKEN_EDGE_P.
5160 If STMT produces a varying value, return SSA_PROP_VARYING. */
5162 static enum ssa_prop_result
5163 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
5169 if (dump_file && (dump_flags & TDF_DETAILS))
5171 fprintf (dump_file, "\nVisiting statement:\n");
5172 print_generic_stmt (dump_file, stmt, dump_flags);
5173 fprintf (dump_file, "\n");
5176 ann = stmt_ann (stmt);
5177 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
5179 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
5181 /* In general, assignments with virtual operands are not useful
5182 for deriving ranges, with the obvious exception of calls to
5183 builtin functions. */
5184 if ((TREE_CODE (rhs) == CALL_EXPR
5185 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
5186 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs), 0))
5187 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
5188 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
5189 return vrp_visit_assignment (stmt, output_p);
5191 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
5192 return vrp_visit_cond_stmt (stmt, taken_edge_p);
5194 /* All other statements produce nothing of interest for VRP, so mark
5195 their outputs varying and prevent further simulation. */
5196 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
5197 set_value_range_to_varying (get_value_range (def));
5199 return SSA_PROP_VARYING;
5203 /* Meet operation for value ranges. Given two value ranges VR0 and
5204 VR1, store in VR0 a range that contains both VR0 and VR1. This
5205 may not be the smallest possible such range. */
5208 vrp_meet (value_range_t *vr0, value_range_t *vr1)
5210 if (vr0->type == VR_UNDEFINED)
5212 copy_value_range (vr0, vr1);
5216 if (vr1->type == VR_UNDEFINED)
5218 /* Nothing to do. VR0 already has the resulting range. */
5222 if (vr0->type == VR_VARYING)
5224 /* Nothing to do. VR0 already has the resulting range. */
5228 if (vr1->type == VR_VARYING)
5230 set_value_range_to_varying (vr0);
5234 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
5239 /* Compute the convex hull of the ranges. The lower limit of
5240 the new range is the minimum of the two ranges. If they
5241 cannot be compared, then give up. */
5242 cmp = compare_values (vr0->min, vr1->min);
5243 if (cmp == 0 || cmp == 1)
5250 /* Similarly, the upper limit of the new range is the maximum
5251 of the two ranges. If they cannot be compared, then
5253 cmp = compare_values (vr0->max, vr1->max);
5254 if (cmp == 0 || cmp == -1)
5261 /* Check for useless ranges. */
5262 if (INTEGRAL_TYPE_P (TREE_TYPE (min))
5263 && ((vrp_val_is_min (min) || is_overflow_infinity (min))
5264 && (vrp_val_is_max (max) || is_overflow_infinity (max))))
5267 /* The resulting set of equivalences is the intersection of
5269 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
5270 bitmap_and_into (vr0->equiv, vr1->equiv);
5271 else if (vr0->equiv && !vr1->equiv)
5272 bitmap_clear (vr0->equiv);
5274 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
5276 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
5278 /* Two anti-ranges meet only if their complements intersect.
5279 Only handle the case of identical ranges. */
5280 if (compare_values (vr0->min, vr1->min) == 0
5281 && compare_values (vr0->max, vr1->max) == 0
5282 && compare_values (vr0->min, vr0->max) == 0)
5284 /* The resulting set of equivalences is the intersection of
5286 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
5287 bitmap_and_into (vr0->equiv, vr1->equiv);
5288 else if (vr0->equiv && !vr1->equiv)
5289 bitmap_clear (vr0->equiv);
5294 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
5296 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
5297 only handle the case where the ranges have an empty intersection.
5298 The result of the meet operation is the anti-range. */
5299 if (!symbolic_range_p (vr0)
5300 && !symbolic_range_p (vr1)
5301 && !value_ranges_intersect_p (vr0, vr1))
5303 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
5304 set. We need to compute the intersection of the two
5305 equivalence sets. */
5306 if (vr1->type == VR_ANTI_RANGE)
5307 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
5309 /* The resulting set of equivalences is the intersection of
5311 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
5312 bitmap_and_into (vr0->equiv, vr1->equiv);
5313 else if (vr0->equiv && !vr1->equiv)
5314 bitmap_clear (vr0->equiv);
5325 /* Failed to find an efficient meet. Before giving up and setting
5326 the result to VARYING, see if we can at least derive a useful
5327 anti-range. FIXME, all this nonsense about distinguishing
5328 anti-ranges from ranges is necessary because of the odd
5329 semantics of range_includes_zero_p and friends. */
5330 if (!symbolic_range_p (vr0)
5331 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
5332 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
5333 && !symbolic_range_p (vr1)
5334 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
5335 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
5337 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
5339 /* Since this meet operation did not result from the meeting of
5340 two equivalent names, VR0 cannot have any equivalences. */
5342 bitmap_clear (vr0->equiv);
5345 set_value_range_to_varying (vr0);
5349 /* Visit all arguments for PHI node PHI that flow through executable
5350 edges. If a valid value range can be derived from all the incoming
5351 value ranges, set a new range for the LHS of PHI. */
5353 static enum ssa_prop_result
5354 vrp_visit_phi_node (tree phi)
5357 tree lhs = PHI_RESULT (phi);
5358 value_range_t *lhs_vr = get_value_range (lhs);
5359 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
5360 int edges, old_edges;
5362 copy_value_range (&vr_result, lhs_vr);
5364 if (dump_file && (dump_flags & TDF_DETAILS))
5366 fprintf (dump_file, "\nVisiting PHI node: ");
5367 print_generic_expr (dump_file, phi, dump_flags);
5371 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
5373 edge e = PHI_ARG_EDGE (phi, i);
5375 if (dump_file && (dump_flags & TDF_DETAILS))
5378 "\n Argument #%d (%d -> %d %sexecutable)\n",
5379 i, e->src->index, e->dest->index,
5380 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
5383 if (e->flags & EDGE_EXECUTABLE)
5385 tree arg = PHI_ARG_DEF (phi, i);
5386 value_range_t vr_arg;
5390 if (TREE_CODE (arg) == SSA_NAME)
5392 vr_arg = *(get_value_range (arg));
5396 if (is_overflow_infinity (arg))
5398 arg = copy_node (arg);
5399 TREE_OVERFLOW (arg) = 0;
5402 vr_arg.type = VR_RANGE;
5405 vr_arg.equiv = NULL;
5408 if (dump_file && (dump_flags & TDF_DETAILS))
5410 fprintf (dump_file, "\t");
5411 print_generic_expr (dump_file, arg, dump_flags);
5412 fprintf (dump_file, "\n\tValue: ");
5413 dump_value_range (dump_file, &vr_arg);
5414 fprintf (dump_file, "\n");
5417 vrp_meet (&vr_result, &vr_arg);
5419 if (vr_result.type == VR_VARYING)
5424 if (vr_result.type == VR_VARYING)
5427 old_edges = vr_phi_edge_counts[SSA_NAME_VERSION (lhs)];
5428 vr_phi_edge_counts[SSA_NAME_VERSION (lhs)] = edges;
5430 /* To prevent infinite iterations in the algorithm, derive ranges
5431 when the new value is slightly bigger or smaller than the
5432 previous one. We don't do this if we have seen a new executable
5433 edge; this helps us avoid an overflow infinity for conditionals
5434 which are not in a loop. */
5435 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE
5436 && edges <= old_edges)
5438 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
5440 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
5441 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
5443 /* If the new minimum is smaller or larger than the previous
5444 one, go all the way to -INF. In the first case, to avoid
5445 iterating millions of times to reach -INF, and in the
5446 other case to avoid infinite bouncing between different
5448 if (cmp_min > 0 || cmp_min < 0)
5450 /* If we will end up with a (-INF, +INF) range, set it
5452 if (vrp_val_is_max (vr_result.max))
5455 if (!needs_overflow_infinity (TREE_TYPE (vr_result.min))
5456 || !vrp_var_may_overflow (lhs, phi))
5457 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
5458 else if (supports_overflow_infinity (TREE_TYPE (vr_result.min)))
5460 negative_overflow_infinity (TREE_TYPE (vr_result.min));
5465 /* Similarly, if the new maximum is smaller or larger than
5466 the previous one, go all the way to +INF. */
5467 if (cmp_max < 0 || cmp_max > 0)
5469 /* If we will end up with a (-INF, +INF) range, set it
5471 if (vrp_val_is_min (vr_result.min))
5474 if (!needs_overflow_infinity (TREE_TYPE (vr_result.max))
5475 || !vrp_var_may_overflow (lhs, phi))
5476 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
5477 else if (supports_overflow_infinity (TREE_TYPE (vr_result.max)))
5479 positive_overflow_infinity (TREE_TYPE (vr_result.max));
5486 /* If the new range is different than the previous value, keep
5488 if (update_value_range (lhs, &vr_result))
5489 return SSA_PROP_INTERESTING;
5491 /* Nothing changed, don't add outgoing edges. */
5492 return SSA_PROP_NOT_INTERESTING;
5494 /* No match found. Set the LHS to VARYING. */
5496 set_value_range_to_varying (lhs_vr);
5497 return SSA_PROP_VARYING;
5500 /* Simplify a division or modulo operator to a right shift or
5501 bitwise and if the first operand is unsigned or is greater
5502 than zero and the second operand is an exact power of two. */
5505 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
5508 tree op = TREE_OPERAND (rhs, 0);
5509 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
5511 if (TYPE_UNSIGNED (TREE_TYPE (op)))
5513 val = integer_one_node;
5519 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node, &sop);
5523 && integer_onep (val)
5524 && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
5528 if (!EXPR_HAS_LOCATION (stmt))
5529 locus = input_location;
5531 locus = EXPR_LOCATION (stmt);
5532 warning (OPT_Wstrict_overflow,
5533 ("%Hassuming signed overflow does not occur when "
5534 "simplifying / or %% to >> or &"),
5539 if (val && integer_onep (val))
5542 tree op0 = TREE_OPERAND (rhs, 0);
5543 tree op1 = TREE_OPERAND (rhs, 1);
5545 if (rhs_code == TRUNC_DIV_EXPR)
5547 t = build_int_cst (NULL_TREE, tree_log2 (op1));
5548 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
5552 t = build_int_cst (TREE_TYPE (op1), 1);
5553 t = int_const_binop (MINUS_EXPR, op1, t, 0);
5554 t = fold_convert (TREE_TYPE (op0), t);
5555 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
5558 GIMPLE_STMT_OPERAND (stmt, 1) = t;
5563 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
5564 ABS_EXPR. If the operand is <= 0, then simplify the
5565 ABS_EXPR into a NEGATE_EXPR. */
5568 simplify_abs_using_ranges (tree stmt, tree rhs)
5571 tree op = TREE_OPERAND (rhs, 0);
5572 tree type = TREE_TYPE (op);
5573 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
5575 if (TYPE_UNSIGNED (type))
5577 val = integer_zero_node;
5583 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node, &sop);
5587 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node,
5592 if (integer_zerop (val))
5593 val = integer_one_node;
5594 else if (integer_onep (val))
5595 val = integer_zero_node;
5600 && (integer_onep (val) || integer_zerop (val)))
5604 if (sop && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
5608 if (!EXPR_HAS_LOCATION (stmt))
5609 locus = input_location;
5611 locus = EXPR_LOCATION (stmt);
5612 warning (OPT_Wstrict_overflow,
5613 ("%Hassuming signed overflow does not occur when "
5614 "simplifying abs (X) to X or -X"),
5618 if (integer_onep (val))
5619 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
5623 GIMPLE_STMT_OPERAND (stmt, 1) = t;
5629 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
5630 a known value range VR.
5632 If there is one and only one value which will satisfy the
5633 conditional, then return that value. Else return NULL. */
5636 test_for_singularity (enum tree_code cond_code, tree op0,
5637 tree op1, value_range_t *vr)
5642 /* Extract minimum/maximum values which satisfy the
5643 the conditional as it was written. */
5644 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
5646 /* This should not be negative infinity; there is no overflow
5648 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
5651 if (cond_code == LT_EXPR && !is_overflow_infinity (max))
5653 tree one = build_int_cst (TREE_TYPE (op0), 1);
5654 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
5656 TREE_NO_WARNING (max) = 1;
5659 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
5661 /* This should not be positive infinity; there is no overflow
5663 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
5666 if (cond_code == GT_EXPR && !is_overflow_infinity (min))
5668 tree one = build_int_cst (TREE_TYPE (op0), 1);
5669 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
5671 TREE_NO_WARNING (min) = 1;
5675 /* Now refine the minimum and maximum values using any
5676 value range information we have for op0. */
5679 if (compare_values (vr->min, min) == -1)
5683 if (compare_values (vr->max, max) == 1)
5688 /* If the new min/max values have converged to a single value,
5689 then there is only one value which can satisfy the condition,
5690 return that value. */
5691 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
5697 /* Simplify a conditional using a relational operator to an equality
5698 test if the range information indicates only one value can satisfy
5699 the original conditional. */
5702 simplify_cond_using_ranges (tree stmt)
5704 tree cond = COND_EXPR_COND (stmt);
5705 tree op0 = TREE_OPERAND (cond, 0);
5706 tree op1 = TREE_OPERAND (cond, 1);
5707 enum tree_code cond_code = TREE_CODE (cond);
5709 if (cond_code != NE_EXPR
5710 && cond_code != EQ_EXPR
5711 && TREE_CODE (op0) == SSA_NAME
5712 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
5713 && is_gimple_min_invariant (op1))
5715 value_range_t *vr = get_value_range (op0);
5717 /* If we have range information for OP0, then we might be
5718 able to simplify this conditional. */
5719 if (vr->type == VR_RANGE)
5721 tree new = test_for_singularity (cond_code, op0, op1, vr);
5727 fprintf (dump_file, "Simplified relational ");
5728 print_generic_expr (dump_file, cond, 0);
5729 fprintf (dump_file, " into ");
5732 COND_EXPR_COND (stmt)
5733 = build2 (EQ_EXPR, boolean_type_node, op0, new);
5738 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
5739 fprintf (dump_file, "\n");
5745 /* Try again after inverting the condition. We only deal
5746 with integral types here, so no need to worry about
5747 issues with inverting FP comparisons. */
5748 cond_code = invert_tree_comparison (cond_code, false);
5749 new = test_for_singularity (cond_code, op0, op1, vr);
5755 fprintf (dump_file, "Simplified relational ");
5756 print_generic_expr (dump_file, cond, 0);
5757 fprintf (dump_file, " into ");
5760 COND_EXPR_COND (stmt)
5761 = build2 (NE_EXPR, boolean_type_node, op0, new);
5766 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
5767 fprintf (dump_file, "\n");
5776 /* Simplify STMT using ranges if possible. */
5779 simplify_stmt_using_ranges (tree stmt)
5781 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
5783 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
5784 enum tree_code rhs_code = TREE_CODE (rhs);
5786 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
5787 and BIT_AND_EXPR respectively if the first operand is greater
5788 than zero and the second operand is an exact power of two. */
5789 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
5790 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
5791 && integer_pow2p (TREE_OPERAND (rhs, 1)))
5792 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
5794 /* Transform ABS (X) into X or -X as appropriate. */
5795 if (rhs_code == ABS_EXPR
5796 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
5797 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
5798 simplify_abs_using_ranges (stmt, rhs);
5800 else if (TREE_CODE (stmt) == COND_EXPR
5801 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
5803 simplify_cond_using_ranges (stmt);
5807 /* Stack of dest,src equivalency pairs that need to be restored after
5808 each attempt to thread a block's incoming edge to an outgoing edge.
5810 A NULL entry is used to mark the end of pairs which need to be
5812 static VEC(tree,heap) *stack;
5814 /* A trivial wrapper so that we can present the generic jump threading
5815 code with a simple API for simplifying statements. STMT is the
5816 statement we want to simplify, WITHIN_STMT provides the location
5817 for any overflow warnings. */
5820 simplify_stmt_for_jump_threading (tree stmt, tree within_stmt)
5822 /* We only use VRP information to simplify conditionals. This is
5823 overly conservative, but it's unclear if doing more would be
5824 worth the compile time cost. */
5825 if (TREE_CODE (stmt) != COND_EXPR)
5828 return vrp_evaluate_conditional (COND_EXPR_COND (stmt), within_stmt);
5831 /* Blocks which have more than one predecessor and more than
5832 one successor present jump threading opportunities. ie,
5833 when the block is reached from a specific predecessor, we
5834 may be able to determine which of the outgoing edges will
5835 be traversed. When this optimization applies, we are able
5836 to avoid conditionals at runtime and we may expose secondary
5837 optimization opportunities.
5839 This routine is effectively a driver for the generic jump
5840 threading code. It basically just presents the generic code
5841 with edges that may be suitable for jump threading.
5843 Unlike DOM, we do not iterate VRP if jump threading was successful.
5844 While iterating may expose new opportunities for VRP, it is expected
5845 those opportunities would be very limited and the compile time cost
5846 to expose those opportunities would be significant.
5848 As jump threading opportunities are discovered, they are registered
5849 for later realization. */
5852 identify_jump_threads (void)
5857 /* Ugh. When substituting values earlier in this pass we can
5858 wipe the dominance information. So rebuild the dominator
5859 information as we need it within the jump threading code. */
5860 calculate_dominance_info (CDI_DOMINATORS);
5862 /* We do not allow VRP information to be used for jump threading
5863 across a back edge in the CFG. Otherwise it becomes too
5864 difficult to avoid eliminating loop exit tests. Of course
5865 EDGE_DFS_BACK is not accurate at this time so we have to
5867 mark_dfs_back_edges ();
5869 /* Allocate our unwinder stack to unwind any temporary equivalences
5870 that might be recorded. */
5871 stack = VEC_alloc (tree, heap, 20);
5873 /* To avoid lots of silly node creation, we create a single
5874 conditional and just modify it in-place when attempting to
5876 dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL);
5877 dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL);
5879 /* Walk through all the blocks finding those which present a
5880 potential jump threading opportunity. We could set this up
5881 as a dominator walker and record data during the walk, but
5882 I doubt it's worth the effort for the classes of jump
5883 threading opportunities we are trying to identify at this
5884 point in compilation. */
5889 /* If the generic jump threading code does not find this block
5890 interesting, then there is nothing to do. */
5891 if (! potentially_threadable_block (bb))
5894 /* We only care about blocks ending in a COND_EXPR. While there
5895 may be some value in handling SWITCH_EXPR here, I doubt it's
5896 terribly important. */
5897 last = bsi_stmt (bsi_last (bb));
5898 if (TREE_CODE (last) != COND_EXPR)
5901 /* We're basically looking for any kind of conditional with
5902 integral type arguments. */
5903 cond = COND_EXPR_COND (last);
5904 if ((TREE_CODE (cond) == SSA_NAME
5905 && INTEGRAL_TYPE_P (TREE_TYPE (cond)))
5906 || (COMPARISON_CLASS_P (cond)
5907 && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
5908 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0)))
5909 && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME
5910 || is_gimple_min_invariant (TREE_OPERAND (cond, 1)))
5911 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
5916 /* We've got a block with multiple predecessors and multiple
5917 successors which also ends in a suitable conditional. For
5918 each predecessor, see if we can thread it to a specific
5920 FOR_EACH_EDGE (e, ei, bb->preds)
5922 /* Do not thread across back edges or abnormal edges
5924 if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
5927 thread_across_edge (dummy, e, true,
5929 simplify_stmt_for_jump_threading);
5934 /* We do not actually update the CFG or SSA graphs at this point as
5935 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
5936 handle ASSERT_EXPRs gracefully. */
5939 /* We identified all the jump threading opportunities earlier, but could
5940 not transform the CFG at that time. This routine transforms the
5941 CFG and arranges for the dominator tree to be rebuilt if necessary.
5943 Note the SSA graph update will occur during the normal TODO
5944 processing by the pass manager. */
5946 finalize_jump_threads (void)
5948 thread_through_all_blocks (false);
5949 VEC_free (tree, heap, stack);
5953 /* Traverse all the blocks folding conditionals with known ranges. */
5959 prop_value_t *single_val_range;
5960 bool do_value_subst_p;
5964 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
5965 dump_all_value_ranges (dump_file);
5966 fprintf (dump_file, "\n");
5969 /* We may have ended with ranges that have exactly one value. Those
5970 values can be substituted as any other copy/const propagated
5971 value using substitute_and_fold. */
5972 single_val_range = XCNEWVEC (prop_value_t, num_ssa_names);
5974 do_value_subst_p = false;
5975 for (i = 0; i < num_ssa_names; i++)
5977 && vr_value[i]->type == VR_RANGE
5978 && vr_value[i]->min == vr_value[i]->max)
5980 single_val_range[i].value = vr_value[i]->min;
5981 do_value_subst_p = true;
5984 if (!do_value_subst_p)
5986 /* We found no single-valued ranges, don't waste time trying to
5987 do single value substitution in substitute_and_fold. */
5988 free (single_val_range);
5989 single_val_range = NULL;
5992 substitute_and_fold (single_val_range, true);
5994 if (warn_array_bounds)
5995 check_all_array_refs ();
5997 /* We must identify jump threading opportunities before we release
5998 the datastructures built by VRP. */
5999 identify_jump_threads ();
6001 /* Free allocated memory. */
6002 for (i = 0; i < num_ssa_names; i++)
6005 BITMAP_FREE (vr_value[i]->equiv);
6009 free (single_val_range);
6011 free (vr_phi_edge_counts);
6013 /* So that we can distinguish between VRP data being available
6014 and not available. */
6016 vr_phi_edge_counts = NULL;
6020 /* Main entry point to VRP (Value Range Propagation). This pass is
6021 loosely based on J. R. C. Patterson, ``Accurate Static Branch
6022 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
6023 Programming Language Design and Implementation, pp. 67-78, 1995.
6024 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
6026 This is essentially an SSA-CCP pass modified to deal with ranges
6027 instead of constants.
6029 While propagating ranges, we may find that two or more SSA name
6030 have equivalent, though distinct ranges. For instance,
6033 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
6035 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
6039 In the code above, pointer p_5 has range [q_2, q_2], but from the
6040 code we can also determine that p_5 cannot be NULL and, if q_2 had
6041 a non-varying range, p_5's range should also be compatible with it.
6043 These equivalences are created by two expressions: ASSERT_EXPR and
6044 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
6045 result of another assertion, then we can use the fact that p_5 and
6046 p_4 are equivalent when evaluating p_5's range.
6048 Together with value ranges, we also propagate these equivalences
6049 between names so that we can take advantage of information from
6050 multiple ranges when doing final replacement. Note that this
6051 equivalency relation is transitive but not symmetric.
6053 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
6054 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
6055 in contexts where that assertion does not hold (e.g., in line 6).
6057 TODO, the main difference between this pass and Patterson's is that
6058 we do not propagate edge probabilities. We only compute whether
6059 edges can be taken or not. That is, instead of having a spectrum
6060 of jump probabilities between 0 and 1, we only deal with 0, 1 and
6061 DON'T KNOW. In the future, it may be worthwhile to propagate
6062 probabilities to aid branch prediction. */
6067 loop_optimizer_init (LOOPS_NORMAL | LOOPS_HAVE_RECORDED_EXITS);
6068 rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa);
6071 insert_range_assertions ();
6074 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
6077 /* ASSERT_EXPRs must be removed before finalizing jump threads
6078 as finalizing jump threads calls the CFG cleanup code which
6079 does not properly handle ASSERT_EXPRs. */
6080 remove_range_assertions ();
6082 /* If we exposed any new variables, go ahead and put them into
6083 SSA form now, before we handle jump threading. This simplifies
6084 interactions between rewriting of _DECL nodes into SSA form
6085 and rewriting SSA_NAME nodes into SSA form after block
6086 duplication and CFG manipulation. */
6087 update_ssa (TODO_update_ssa);
6089 finalize_jump_threads ();
6091 loop_optimizer_finalize ();
6099 return flag_tree_vrp != 0;
6102 struct tree_opt_pass pass_vrp =
6105 gate_vrp, /* gate */
6106 execute_vrp, /* execute */
6109 0, /* static_pass_number */
6110 TV_TREE_VRP, /* tv_id */
6111 PROP_ssa | PROP_alias, /* properties_required */
6112 0, /* properties_provided */
6113 0, /* properties_destroyed */
6114 0, /* todo_flags_start */
6119 | TODO_update_ssa, /* todo_flags_finish */