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 *strict_overflow_p = true;
843 if (code1 == SSA_NAME)
845 if (code2 == PLUS_EXPR)
846 /* NAME < NAME + CST */
848 else if (code2 == MINUS_EXPR)
849 /* NAME > NAME - CST */
852 else if (code1 == PLUS_EXPR)
854 if (code2 == SSA_NAME)
855 /* NAME + CST > NAME */
857 else if (code2 == PLUS_EXPR)
858 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
859 return compare_values_warnv (c1, c2, strict_overflow_p);
860 else if (code2 == MINUS_EXPR)
861 /* NAME + CST1 > NAME - CST2 */
864 else if (code1 == MINUS_EXPR)
866 if (code2 == SSA_NAME)
867 /* NAME - CST < NAME */
869 else if (code2 == PLUS_EXPR)
870 /* NAME - CST1 < NAME + CST2 */
872 else if (code2 == MINUS_EXPR)
873 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
874 C1 and C2 are swapped in the call to compare_values. */
875 return compare_values_warnv (c2, c1, strict_overflow_p);
881 /* We cannot compare non-constants. */
882 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
885 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
887 /* We cannot compare overflowed values, except for overflow
889 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
891 if (strict_overflow_p != NULL)
892 *strict_overflow_p = true;
893 if (is_negative_overflow_infinity (val1))
894 return is_negative_overflow_infinity (val2) ? 0 : -1;
895 else if (is_negative_overflow_infinity (val2))
897 else if (is_positive_overflow_infinity (val1))
898 return is_positive_overflow_infinity (val2) ? 0 : 1;
899 else if (is_positive_overflow_infinity (val2))
904 return tree_int_cst_compare (val1, val2);
910 /* First see if VAL1 and VAL2 are not the same. */
911 if (val1 == val2 || operand_equal_p (val1, val2, 0))
914 /* If VAL1 is a lower address than VAL2, return -1. */
915 if (operand_less_p (val1, val2) == 1)
918 /* If VAL1 is a higher address than VAL2, return +1. */
919 if (operand_less_p (val2, val1) == 1)
922 /* If VAL1 is different than VAL2, return +2.
923 For integer constants we either have already returned -1 or 1
924 or they are equivalent. We still might succeed in proving
925 something about non-trivial operands. */
926 if (TREE_CODE (val1) != INTEGER_CST
927 || TREE_CODE (val2) != INTEGER_CST)
929 t = fold_binary_to_constant (NE_EXPR, boolean_type_node, val1, val2);
930 if (t && tree_expr_nonzero_p (t))
938 /* Compare values like compare_values_warnv, but treat comparisons of
939 nonconstants which rely on undefined overflow as incomparable. */
942 compare_values (tree val1, tree val2)
948 ret = compare_values_warnv (val1, val2, &sop);
950 && (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2)))
956 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
957 0 if VAL is not inside VR,
958 -2 if we cannot tell either way.
960 FIXME, the current semantics of this functions are a bit quirky
961 when taken in the context of VRP. In here we do not care
962 about VR's type. If VR is the anti-range ~[3, 5] the call
963 value_inside_range (4, VR) will return 1.
965 This is counter-intuitive in a strict sense, but the callers
966 currently expect this. They are calling the function
967 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
968 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
971 This also applies to value_ranges_intersect_p and
972 range_includes_zero_p. The semantics of VR_RANGE and
973 VR_ANTI_RANGE should be encoded here, but that also means
974 adapting the users of these functions to the new semantics.
976 Benchmark compile/20001226-1.c compilation time after changing this
980 value_inside_range (tree val, value_range_t * vr)
984 cmp1 = operand_less_p (val, vr->min);
990 cmp2 = operand_less_p (vr->max, val);
998 /* Return true if value ranges VR0 and VR1 have a non-empty
1001 Benchmark compile/20001226-1.c compilation time after changing this
1006 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
1008 /* The value ranges do not intersect if the maximum of the first range is
1009 less than the minimum of the second range or vice versa.
1010 When those relations are unknown, we can't do any better. */
1011 if (operand_less_p (vr0->max, vr1->min) != 0)
1013 if (operand_less_p (vr1->max, vr0->min) != 0)
1019 /* Return true if VR includes the value zero, false otherwise. FIXME,
1020 currently this will return false for an anti-range like ~[-4, 3].
1021 This will be wrong when the semantics of value_inside_range are
1022 modified (currently the users of this function expect these
1026 range_includes_zero_p (value_range_t *vr)
1030 gcc_assert (vr->type != VR_UNDEFINED
1031 && vr->type != VR_VARYING
1032 && !symbolic_range_p (vr));
1034 zero = build_int_cst (TREE_TYPE (vr->min), 0);
1035 return (value_inside_range (zero, vr) == 1);
1038 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
1039 false otherwise or if no value range information is available. */
1042 ssa_name_nonnegative_p (tree t)
1044 value_range_t *vr = get_value_range (t);
1049 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
1050 which would return a useful value should be encoded as a VR_RANGE. */
1051 if (vr->type == VR_RANGE)
1053 int result = compare_values (vr->min, integer_zero_node);
1055 return (result == 0 || result == 1);
1060 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
1061 false otherwise or if no value range information is available. */
1064 ssa_name_nonzero_p (tree t)
1066 value_range_t *vr = get_value_range (t);
1071 /* A VR_RANGE which does not include zero is a nonzero value. */
1072 if (vr->type == VR_RANGE && !symbolic_range_p (vr))
1073 return ! range_includes_zero_p (vr);
1075 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
1076 if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr))
1077 return range_includes_zero_p (vr);
1083 /* Extract value range information from an ASSERT_EXPR EXPR and store
1087 extract_range_from_assert (value_range_t *vr_p, tree expr)
1089 tree var, cond, limit, min, max, type;
1090 value_range_t *var_vr, *limit_vr;
1091 enum tree_code cond_code;
1093 var = ASSERT_EXPR_VAR (expr);
1094 cond = ASSERT_EXPR_COND (expr);
1096 gcc_assert (COMPARISON_CLASS_P (cond));
1098 /* Find VAR in the ASSERT_EXPR conditional. */
1099 if (var == TREE_OPERAND (cond, 0))
1101 /* If the predicate is of the form VAR COMP LIMIT, then we just
1102 take LIMIT from the RHS and use the same comparison code. */
1103 limit = TREE_OPERAND (cond, 1);
1104 cond_code = TREE_CODE (cond);
1108 /* If the predicate is of the form LIMIT COMP VAR, then we need
1109 to flip around the comparison code to create the proper range
1111 limit = TREE_OPERAND (cond, 0);
1112 cond_code = swap_tree_comparison (TREE_CODE (cond));
1115 limit = avoid_overflow_infinity (limit);
1117 type = TREE_TYPE (limit);
1118 gcc_assert (limit != var);
1120 /* For pointer arithmetic, we only keep track of pointer equality
1122 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
1124 set_value_range_to_varying (vr_p);
1128 /* If LIMIT is another SSA name and LIMIT has a range of its own,
1129 try to use LIMIT's range to avoid creating symbolic ranges
1131 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
1133 /* LIMIT's range is only interesting if it has any useful information. */
1135 && (limit_vr->type == VR_UNDEFINED
1136 || limit_vr->type == VR_VARYING
1137 || symbolic_range_p (limit_vr)))
1140 /* Initially, the new range has the same set of equivalences of
1141 VAR's range. This will be revised before returning the final
1142 value. Since assertions may be chained via mutually exclusive
1143 predicates, we will need to trim the set of equivalences before
1145 gcc_assert (vr_p->equiv == NULL);
1146 add_equivalence (&vr_p->equiv, var);
1148 /* Extract a new range based on the asserted comparison for VAR and
1149 LIMIT's value range. Notice that if LIMIT has an anti-range, we
1150 will only use it for equality comparisons (EQ_EXPR). For any
1151 other kind of assertion, we cannot derive a range from LIMIT's
1152 anti-range that can be used to describe the new range. For
1153 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
1154 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
1155 no single range for x_2 that could describe LE_EXPR, so we might
1156 as well build the range [b_4, +INF] for it. */
1157 if (cond_code == EQ_EXPR)
1159 enum value_range_type range_type;
1163 range_type = limit_vr->type;
1164 min = limit_vr->min;
1165 max = limit_vr->max;
1169 range_type = VR_RANGE;
1174 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
1176 /* When asserting the equality VAR == LIMIT and LIMIT is another
1177 SSA name, the new range will also inherit the equivalence set
1179 if (TREE_CODE (limit) == SSA_NAME)
1180 add_equivalence (&vr_p->equiv, limit);
1182 else if (cond_code == NE_EXPR)
1184 /* As described above, when LIMIT's range is an anti-range and
1185 this assertion is an inequality (NE_EXPR), then we cannot
1186 derive anything from the anti-range. For instance, if
1187 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
1188 not imply that VAR's range is [0, 0]. So, in the case of
1189 anti-ranges, we just assert the inequality using LIMIT and
1192 If LIMIT_VR is a range, we can only use it to build a new
1193 anti-range if LIMIT_VR is a single-valued range. For
1194 instance, if LIMIT_VR is [0, 1], the predicate
1195 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
1196 Rather, it means that for value 0 VAR should be ~[0, 0]
1197 and for value 1, VAR should be ~[1, 1]. We cannot
1198 represent these ranges.
1200 The only situation in which we can build a valid
1201 anti-range is when LIMIT_VR is a single-valued range
1202 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
1203 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
1205 && limit_vr->type == VR_RANGE
1206 && compare_values (limit_vr->min, limit_vr->max) == 0)
1208 min = limit_vr->min;
1209 max = limit_vr->max;
1213 /* In any other case, we cannot use LIMIT's range to build a
1214 valid anti-range. */
1218 /* If MIN and MAX cover the whole range for their type, then
1219 just use the original LIMIT. */
1220 if (INTEGRAL_TYPE_P (type)
1221 && vrp_val_is_min (min)
1222 && vrp_val_is_max (max))
1225 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
1227 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
1229 min = TYPE_MIN_VALUE (type);
1231 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
1235 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1236 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
1238 max = limit_vr->max;
1241 /* If the maximum value forces us to be out of bounds, simply punt.
1242 It would be pointless to try and do anything more since this
1243 all should be optimized away above us. */
1244 if ((cond_code == LT_EXPR
1245 && compare_values (max, min) == 0)
1246 || is_overflow_infinity (max))
1247 set_value_range_to_varying (vr_p);
1250 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
1251 if (cond_code == LT_EXPR)
1253 tree one = build_int_cst (type, 1);
1254 max = fold_build2 (MINUS_EXPR, type, max, one);
1257 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1260 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
1262 max = TYPE_MAX_VALUE (type);
1264 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
1268 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1269 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
1271 min = limit_vr->min;
1274 /* If the minimum value forces us to be out of bounds, simply punt.
1275 It would be pointless to try and do anything more since this
1276 all should be optimized away above us. */
1277 if ((cond_code == GT_EXPR
1278 && compare_values (min, max) == 0)
1279 || is_overflow_infinity (min))
1280 set_value_range_to_varying (vr_p);
1283 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
1284 if (cond_code == GT_EXPR)
1286 tree one = build_int_cst (type, 1);
1287 min = fold_build2 (PLUS_EXPR, type, min, one);
1290 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1296 /* If VAR already had a known range, it may happen that the new
1297 range we have computed and VAR's range are not compatible. For
1301 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
1303 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
1305 While the above comes from a faulty program, it will cause an ICE
1306 later because p_8 and p_6 will have incompatible ranges and at
1307 the same time will be considered equivalent. A similar situation
1311 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
1313 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
1315 Again i_6 and i_7 will have incompatible ranges. It would be
1316 pointless to try and do anything with i_7's range because
1317 anything dominated by 'if (i_5 < 5)' will be optimized away.
1318 Note, due to the wa in which simulation proceeds, the statement
1319 i_7 = ASSERT_EXPR <...> we would never be visited because the
1320 conditional 'if (i_5 < 5)' always evaluates to false. However,
1321 this extra check does not hurt and may protect against future
1322 changes to VRP that may get into a situation similar to the
1323 NULL pointer dereference example.
1325 Note that these compatibility tests are only needed when dealing
1326 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1327 are both anti-ranges, they will always be compatible, because two
1328 anti-ranges will always have a non-empty intersection. */
1330 var_vr = get_value_range (var);
1332 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1333 ranges or anti-ranges. */
1334 if (vr_p->type == VR_VARYING
1335 || vr_p->type == VR_UNDEFINED
1336 || var_vr->type == VR_VARYING
1337 || var_vr->type == VR_UNDEFINED
1338 || symbolic_range_p (vr_p)
1339 || symbolic_range_p (var_vr))
1342 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
1344 /* If the two ranges have a non-empty intersection, we can
1345 refine the resulting range. Since the assert expression
1346 creates an equivalency and at the same time it asserts a
1347 predicate, we can take the intersection of the two ranges to
1348 get better precision. */
1349 if (value_ranges_intersect_p (var_vr, vr_p))
1351 /* Use the larger of the two minimums. */
1352 if (compare_values (vr_p->min, var_vr->min) == -1)
1357 /* Use the smaller of the two maximums. */
1358 if (compare_values (vr_p->max, var_vr->max) == 1)
1363 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
1367 /* The two ranges do not intersect, set the new range to
1368 VARYING, because we will not be able to do anything
1369 meaningful with it. */
1370 set_value_range_to_varying (vr_p);
1373 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
1374 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
1376 /* A range and an anti-range will cancel each other only if
1377 their ends are the same. For instance, in the example above,
1378 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1379 so VR_P should be set to VR_VARYING. */
1380 if (compare_values (var_vr->min, vr_p->min) == 0
1381 && compare_values (var_vr->max, vr_p->max) == 0)
1382 set_value_range_to_varying (vr_p);
1385 tree min, max, anti_min, anti_max, real_min, real_max;
1388 /* We want to compute the logical AND of the two ranges;
1389 there are three cases to consider.
1392 1. The VR_ANTI_RANGE range is completely within the
1393 VR_RANGE and the endpoints of the ranges are
1394 different. In that case the resulting range
1395 should be whichever range is more precise.
1396 Typically that will be the VR_RANGE.
1398 2. The VR_ANTI_RANGE is completely disjoint from
1399 the VR_RANGE. In this case the resulting range
1400 should be the VR_RANGE.
1402 3. There is some overlap between the VR_ANTI_RANGE
1405 3a. If the high limit of the VR_ANTI_RANGE resides
1406 within the VR_RANGE, then the result is a new
1407 VR_RANGE starting at the high limit of the
1408 the VR_ANTI_RANGE + 1 and extending to the
1409 high limit of the original VR_RANGE.
1411 3b. If the low limit of the VR_ANTI_RANGE resides
1412 within the VR_RANGE, then the result is a new
1413 VR_RANGE starting at the low limit of the original
1414 VR_RANGE and extending to the low limit of the
1415 VR_ANTI_RANGE - 1. */
1416 if (vr_p->type == VR_ANTI_RANGE)
1418 anti_min = vr_p->min;
1419 anti_max = vr_p->max;
1420 real_min = var_vr->min;
1421 real_max = var_vr->max;
1425 anti_min = var_vr->min;
1426 anti_max = var_vr->max;
1427 real_min = vr_p->min;
1428 real_max = vr_p->max;
1432 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1433 not including any endpoints. */
1434 if (compare_values (anti_max, real_max) == -1
1435 && compare_values (anti_min, real_min) == 1)
1437 set_value_range (vr_p, VR_RANGE, real_min,
1438 real_max, vr_p->equiv);
1440 /* Case 2, VR_ANTI_RANGE completely disjoint from
1442 else if (compare_values (anti_min, real_max) == 1
1443 || compare_values (anti_max, real_min) == -1)
1445 set_value_range (vr_p, VR_RANGE, real_min,
1446 real_max, vr_p->equiv);
1448 /* Case 3a, the anti-range extends into the low
1449 part of the real range. Thus creating a new
1450 low for the real range. */
1451 else if (((cmp = compare_values (anti_max, real_min)) == 1
1453 && compare_values (anti_max, real_max) == -1)
1455 gcc_assert (!is_positive_overflow_infinity (anti_max));
1456 if (needs_overflow_infinity (TREE_TYPE (anti_max))
1457 && vrp_val_is_max (anti_max))
1459 if (!supports_overflow_infinity (TREE_TYPE (var_vr->min)))
1461 set_value_range_to_varying (vr_p);
1464 min = positive_overflow_infinity (TREE_TYPE (var_vr->min));
1467 min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min),
1469 build_int_cst (TREE_TYPE (var_vr->min), 1));
1471 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1473 /* Case 3b, the anti-range extends into the high
1474 part of the real range. Thus creating a new
1475 higher for the real range. */
1476 else if (compare_values (anti_min, real_min) == 1
1477 && ((cmp = compare_values (anti_min, real_max)) == -1
1480 gcc_assert (!is_negative_overflow_infinity (anti_min));
1481 if (needs_overflow_infinity (TREE_TYPE (anti_min))
1482 && vrp_val_is_min (anti_min))
1484 if (!supports_overflow_infinity (TREE_TYPE (var_vr->min)))
1486 set_value_range_to_varying (vr_p);
1489 max = negative_overflow_infinity (TREE_TYPE (var_vr->min));
1492 max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min),
1494 build_int_cst (TREE_TYPE (var_vr->min), 1));
1496 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1503 /* Extract range information from SSA name VAR and store it in VR. If
1504 VAR has an interesting range, use it. Otherwise, create the
1505 range [VAR, VAR] and return it. This is useful in situations where
1506 we may have conditionals testing values of VARYING names. For
1513 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1517 extract_range_from_ssa_name (value_range_t *vr, tree var)
1519 value_range_t *var_vr = get_value_range (var);
1521 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
1522 copy_value_range (vr, var_vr);
1524 set_value_range (vr, VR_RANGE, var, var, NULL);
1526 add_equivalence (&vr->equiv, var);
1530 /* Wrapper around int_const_binop. If the operation overflows and we
1531 are not using wrapping arithmetic, then adjust the result to be
1532 -INF or +INF depending on CODE, VAL1 and VAL2. This can return
1533 NULL_TREE if we need to use an overflow infinity representation but
1534 the type does not support it. */
1537 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
1541 res = int_const_binop (code, val1, val2, 0);
1543 /* If we are not using wrapping arithmetic, operate symbolically
1544 on -INF and +INF. */
1545 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1)))
1547 int checkz = compare_values (res, val1);
1548 bool overflow = false;
1550 /* Ensure that res = val1 [+*] val2 >= val1
1551 or that res = val1 - val2 <= val1. */
1552 if ((code == PLUS_EXPR
1553 && !(checkz == 1 || checkz == 0))
1554 || (code == MINUS_EXPR
1555 && !(checkz == 0 || checkz == -1)))
1559 /* Checking for multiplication overflow is done by dividing the
1560 output of the multiplication by the first input of the
1561 multiplication. If the result of that division operation is
1562 not equal to the second input of the multiplication, then the
1563 multiplication overflowed. */
1564 else if (code == MULT_EXPR && !integer_zerop (val1))
1566 tree tmp = int_const_binop (TRUNC_DIV_EXPR,
1569 int check = compare_values (tmp, val2);
1577 res = copy_node (res);
1578 TREE_OVERFLOW (res) = 1;
1582 else if ((TREE_OVERFLOW (res)
1583 && !TREE_OVERFLOW (val1)
1584 && !TREE_OVERFLOW (val2))
1585 || is_overflow_infinity (val1)
1586 || is_overflow_infinity (val2))
1588 /* If the operation overflowed but neither VAL1 nor VAL2 are
1589 overflown, return -INF or +INF depending on the operation
1590 and the combination of signs of the operands. */
1591 int sgn1 = tree_int_cst_sgn (val1);
1592 int sgn2 = tree_int_cst_sgn (val2);
1594 if (needs_overflow_infinity (TREE_TYPE (res))
1595 && !supports_overflow_infinity (TREE_TYPE (res)))
1598 /* We have to punt on adding infinities of different signs,
1599 since we can't tell what the sign of the result should be.
1600 Likewise for subtracting infinities of the same sign. */
1601 if (((code == PLUS_EXPR && sgn1 != sgn2)
1602 || (code == MINUS_EXPR && sgn1 == sgn2))
1603 && is_overflow_infinity (val1)
1604 && is_overflow_infinity (val2))
1607 /* Don't try to handle division or shifting of infinities. */
1608 if ((code == TRUNC_DIV_EXPR
1609 || code == FLOOR_DIV_EXPR
1610 || code == CEIL_DIV_EXPR
1611 || code == EXACT_DIV_EXPR
1612 || code == ROUND_DIV_EXPR
1613 || code == RSHIFT_EXPR)
1614 && (is_overflow_infinity (val1)
1615 || is_overflow_infinity (val2)))
1618 /* Notice that we only need to handle the restricted set of
1619 operations handled by extract_range_from_binary_expr.
1620 Among them, only multiplication, addition and subtraction
1621 can yield overflow without overflown operands because we
1622 are working with integral types only... except in the
1623 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1624 for division too. */
1626 /* For multiplication, the sign of the overflow is given
1627 by the comparison of the signs of the operands. */
1628 if ((code == MULT_EXPR && sgn1 == sgn2)
1629 /* For addition, the operands must be of the same sign
1630 to yield an overflow. Its sign is therefore that
1631 of one of the operands, for example the first. For
1632 infinite operands X + -INF is negative, not positive. */
1633 || (code == PLUS_EXPR
1635 ? !is_negative_overflow_infinity (val2)
1636 : is_positive_overflow_infinity (val2)))
1637 /* For subtraction, non-infinite operands must be of
1638 different signs to yield an overflow. Its sign is
1639 therefore that of the first operand or the opposite of
1640 that of the second operand. A first operand of 0 counts
1641 as positive here, for the corner case 0 - (-INF), which
1642 overflows, but must yield +INF. For infinite operands 0
1643 - INF is negative, not positive. */
1644 || (code == MINUS_EXPR
1646 ? !is_positive_overflow_infinity (val2)
1647 : is_negative_overflow_infinity (val2)))
1648 /* We only get in here with positive shift count, so the
1649 overflow direction is the same as the sign of val1.
1650 Actually rshift does not overflow at all, but we only
1651 handle the case of shifting overflowed -INF and +INF. */
1652 || (code == RSHIFT_EXPR
1654 /* For division, the only case is -INF / -1 = +INF. */
1655 || code == TRUNC_DIV_EXPR
1656 || code == FLOOR_DIV_EXPR
1657 || code == CEIL_DIV_EXPR
1658 || code == EXACT_DIV_EXPR
1659 || code == ROUND_DIV_EXPR)
1660 return (needs_overflow_infinity (TREE_TYPE (res))
1661 ? positive_overflow_infinity (TREE_TYPE (res))
1662 : TYPE_MAX_VALUE (TREE_TYPE (res)));
1664 return (needs_overflow_infinity (TREE_TYPE (res))
1665 ? negative_overflow_infinity (TREE_TYPE (res))
1666 : TYPE_MIN_VALUE (TREE_TYPE (res)));
1673 /* Extract range information from a binary expression EXPR based on
1674 the ranges of each of its operands and the expression code. */
1677 extract_range_from_binary_expr (value_range_t *vr, tree expr)
1679 enum tree_code code = TREE_CODE (expr);
1680 enum value_range_type type;
1681 tree op0, op1, min, max;
1683 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1684 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1686 /* Not all binary expressions can be applied to ranges in a
1687 meaningful way. Handle only arithmetic operations. */
1688 if (code != PLUS_EXPR
1689 && code != MINUS_EXPR
1690 && code != MULT_EXPR
1691 && code != TRUNC_DIV_EXPR
1692 && code != FLOOR_DIV_EXPR
1693 && code != CEIL_DIV_EXPR
1694 && code != EXACT_DIV_EXPR
1695 && code != ROUND_DIV_EXPR
1696 && code != RSHIFT_EXPR
1699 && code != BIT_AND_EXPR
1700 && code != TRUTH_ANDIF_EXPR
1701 && code != TRUTH_ORIF_EXPR
1702 && code != TRUTH_AND_EXPR
1703 && code != TRUTH_OR_EXPR)
1705 set_value_range_to_varying (vr);
1709 /* Get value ranges for each operand. For constant operands, create
1710 a new value range with the operand to simplify processing. */
1711 op0 = TREE_OPERAND (expr, 0);
1712 if (TREE_CODE (op0) == SSA_NAME)
1713 vr0 = *(get_value_range (op0));
1714 else if (is_gimple_min_invariant (op0))
1715 set_value_range_to_value (&vr0, op0, NULL);
1717 set_value_range_to_varying (&vr0);
1719 op1 = TREE_OPERAND (expr, 1);
1720 if (TREE_CODE (op1) == SSA_NAME)
1721 vr1 = *(get_value_range (op1));
1722 else if (is_gimple_min_invariant (op1))
1723 set_value_range_to_value (&vr1, op1, NULL);
1725 set_value_range_to_varying (&vr1);
1727 /* If either range is UNDEFINED, so is the result. */
1728 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1730 set_value_range_to_undefined (vr);
1734 /* The type of the resulting value range defaults to VR0.TYPE. */
1737 /* Refuse to operate on VARYING ranges, ranges of different kinds
1738 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1739 because we may be able to derive a useful range even if one of
1740 the operands is VR_VARYING or symbolic range. TODO, we may be
1741 able to derive anti-ranges in some cases. */
1742 if (code != BIT_AND_EXPR
1743 && code != TRUTH_AND_EXPR
1744 && code != TRUTH_OR_EXPR
1745 && (vr0.type == VR_VARYING
1746 || vr1.type == VR_VARYING
1747 || vr0.type != vr1.type
1748 || symbolic_range_p (&vr0)
1749 || symbolic_range_p (&vr1)))
1751 set_value_range_to_varying (vr);
1755 /* Now evaluate the expression to determine the new range. */
1756 if (POINTER_TYPE_P (TREE_TYPE (expr))
1757 || POINTER_TYPE_P (TREE_TYPE (op0))
1758 || POINTER_TYPE_P (TREE_TYPE (op1)))
1760 /* For pointer types, we are really only interested in asserting
1761 whether the expression evaluates to non-NULL. FIXME, we used
1762 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1763 ivopts is generating expressions with pointer multiplication
1765 if (code == PLUS_EXPR)
1767 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1768 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1769 else if (range_is_null (&vr0) && range_is_null (&vr1))
1770 set_value_range_to_null (vr, TREE_TYPE (expr));
1772 set_value_range_to_varying (vr);
1776 /* Subtracting from a pointer, may yield 0, so just drop the
1777 resulting range to varying. */
1778 set_value_range_to_varying (vr);
1784 /* For integer ranges, apply the operation to each end of the
1785 range and see what we end up with. */
1786 if (code == TRUTH_ANDIF_EXPR
1787 || code == TRUTH_ORIF_EXPR
1788 || code == TRUTH_AND_EXPR
1789 || code == TRUTH_OR_EXPR)
1791 /* If one of the operands is zero, we know that the whole
1792 expression evaluates zero. */
1793 if (code == TRUTH_AND_EXPR
1794 && ((vr0.type == VR_RANGE
1795 && integer_zerop (vr0.min)
1796 && integer_zerop (vr0.max))
1797 || (vr1.type == VR_RANGE
1798 && integer_zerop (vr1.min)
1799 && integer_zerop (vr1.max))))
1802 min = max = build_int_cst (TREE_TYPE (expr), 0);
1804 /* If one of the operands is one, we know that the whole
1805 expression evaluates one. */
1806 else if (code == TRUTH_OR_EXPR
1807 && ((vr0.type == VR_RANGE
1808 && integer_onep (vr0.min)
1809 && integer_onep (vr0.max))
1810 || (vr1.type == VR_RANGE
1811 && integer_onep (vr1.min)
1812 && integer_onep (vr1.max))))
1815 min = max = build_int_cst (TREE_TYPE (expr), 1);
1817 else if (vr0.type != VR_VARYING
1818 && vr1.type != VR_VARYING
1819 && vr0.type == vr1.type
1820 && !symbolic_range_p (&vr0)
1821 && !overflow_infinity_range_p (&vr0)
1822 && !symbolic_range_p (&vr1)
1823 && !overflow_infinity_range_p (&vr1))
1825 /* Boolean expressions cannot be folded with int_const_binop. */
1826 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1827 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1831 /* The result of a TRUTH_*_EXPR is always true or false. */
1832 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
1836 else if (code == PLUS_EXPR
1838 || code == MAX_EXPR)
1840 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1841 VR_VARYING. It would take more effort to compute a precise
1842 range for such a case. For example, if we have op0 == 1 and
1843 op1 == -1 with their ranges both being ~[0,0], we would have
1844 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1845 Note that we are guaranteed to have vr0.type == vr1.type at
1847 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1849 set_value_range_to_varying (vr);
1853 /* For operations that make the resulting range directly
1854 proportional to the original ranges, apply the operation to
1855 the same end of each range. */
1856 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1857 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1859 else if (code == MULT_EXPR
1860 || code == TRUNC_DIV_EXPR
1861 || code == FLOOR_DIV_EXPR
1862 || code == CEIL_DIV_EXPR
1863 || code == EXACT_DIV_EXPR
1864 || code == ROUND_DIV_EXPR
1865 || code == RSHIFT_EXPR)
1871 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1872 drop to VR_VARYING. It would take more effort to compute a
1873 precise range for such a case. For example, if we have
1874 op0 == 65536 and op1 == 65536 with their ranges both being
1875 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1876 we cannot claim that the product is in ~[0,0]. Note that we
1877 are guaranteed to have vr0.type == vr1.type at this
1879 if (code == MULT_EXPR
1880 && vr0.type == VR_ANTI_RANGE
1881 && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0)))
1883 set_value_range_to_varying (vr);
1887 /* If we have a RSHIFT_EXPR with any shift values outside [0..prec-1],
1888 then drop to VR_VARYING. Outside of this range we get undefined
1889 behavior from the shift operation. We cannot even trust
1890 SHIFT_COUNT_TRUNCATED at this stage, because that applies to rtl
1891 shifts, and the operation at the tree level may be widened. */
1892 if (code == RSHIFT_EXPR)
1894 if (vr1.type == VR_ANTI_RANGE
1895 || !vrp_expr_computes_nonnegative (op1, &sop)
1897 (build_int_cst (TREE_TYPE (vr1.max),
1898 TYPE_PRECISION (TREE_TYPE (expr)) - 1),
1901 set_value_range_to_varying (vr);
1906 /* Multiplications and divisions are a bit tricky to handle,
1907 depending on the mix of signs we have in the two ranges, we
1908 need to operate on different values to get the minimum and
1909 maximum values for the new range. One approach is to figure
1910 out all the variations of range combinations and do the
1913 However, this involves several calls to compare_values and it
1914 is pretty convoluted. It's simpler to do the 4 operations
1915 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1916 MAX1) and then figure the smallest and largest values to form
1919 /* Divisions by zero result in a VARYING value. */
1920 else if (code != MULT_EXPR
1921 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1923 set_value_range_to_varying (vr);
1927 /* Compute the 4 cross operations. */
1929 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1930 if (val[0] == NULL_TREE)
1933 if (vr1.max == vr1.min)
1937 val[1] = vrp_int_const_binop (code, vr0.min, vr1.max);
1938 if (val[1] == NULL_TREE)
1942 if (vr0.max == vr0.min)
1946 val[2] = vrp_int_const_binop (code, vr0.max, vr1.min);
1947 if (val[2] == NULL_TREE)
1951 if (vr0.min == vr0.max || vr1.min == vr1.max)
1955 val[3] = vrp_int_const_binop (code, vr0.max, vr1.max);
1956 if (val[3] == NULL_TREE)
1962 set_value_range_to_varying (vr);
1966 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1970 for (i = 1; i < 4; i++)
1972 if (!is_gimple_min_invariant (min)
1973 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
1974 || !is_gimple_min_invariant (max)
1975 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
1980 if (!is_gimple_min_invariant (val[i])
1981 || (TREE_OVERFLOW (val[i])
1982 && !is_overflow_infinity (val[i])))
1984 /* If we found an overflowed value, set MIN and MAX
1985 to it so that we set the resulting range to
1991 if (compare_values (val[i], min) == -1)
1994 if (compare_values (val[i], max) == 1)
1999 else if (code == MINUS_EXPR)
2001 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
2002 VR_VARYING. It would take more effort to compute a precise
2003 range for such a case. For example, if we have op0 == 1 and
2004 op1 == 1 with their ranges both being ~[0,0], we would have
2005 op0 - op1 == 0, so we cannot claim that the difference is in
2006 ~[0,0]. Note that we are guaranteed to have
2007 vr0.type == vr1.type at this point. */
2008 if (vr0.type == VR_ANTI_RANGE)
2010 set_value_range_to_varying (vr);
2014 /* For MINUS_EXPR, apply the operation to the opposite ends of
2016 min = vrp_int_const_binop (code, vr0.min, vr1.max);
2017 max = vrp_int_const_binop (code, vr0.max, vr1.min);
2019 else if (code == BIT_AND_EXPR)
2021 if (vr0.type == VR_RANGE
2022 && vr0.min == vr0.max
2023 && TREE_CODE (vr0.max) == INTEGER_CST
2024 && !TREE_OVERFLOW (vr0.max)
2025 && tree_int_cst_sgn (vr0.max) >= 0)
2027 min = build_int_cst (TREE_TYPE (expr), 0);
2030 else if (vr1.type == VR_RANGE
2031 && vr1.min == vr1.max
2032 && TREE_CODE (vr1.max) == INTEGER_CST
2033 && !TREE_OVERFLOW (vr1.max)
2034 && tree_int_cst_sgn (vr1.max) >= 0)
2037 min = build_int_cst (TREE_TYPE (expr), 0);
2042 set_value_range_to_varying (vr);
2049 /* If either MIN or MAX overflowed, then set the resulting range to
2050 VARYING. But we do accept an overflow infinity
2052 if (min == NULL_TREE
2053 || !is_gimple_min_invariant (min)
2054 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
2056 || !is_gimple_min_invariant (max)
2057 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
2059 set_value_range_to_varying (vr);
2065 2) [-INF, +-INF(OVF)]
2066 3) [+-INF(OVF), +INF]
2067 4) [+-INF(OVF), +-INF(OVF)]
2068 We learn nothing when we have INF and INF(OVF) on both sides.
2069 Note that we do accept [-INF, -INF] and [+INF, +INF] without
2071 if ((vrp_val_is_min (min) || is_overflow_infinity (min))
2072 && (vrp_val_is_max (max) || is_overflow_infinity (max)))
2074 set_value_range_to_varying (vr);
2078 cmp = compare_values (min, max);
2079 if (cmp == -2 || cmp == 1)
2081 /* If the new range has its limits swapped around (MIN > MAX),
2082 then the operation caused one of them to wrap around, mark
2083 the new range VARYING. */
2084 set_value_range_to_varying (vr);
2087 set_value_range (vr, type, min, max, NULL);
2091 /* Extract range information from a unary expression EXPR based on
2092 the range of its operand and the expression code. */
2095 extract_range_from_unary_expr (value_range_t *vr, tree expr)
2097 enum tree_code code = TREE_CODE (expr);
2100 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2102 /* Refuse to operate on certain unary expressions for which we
2103 cannot easily determine a resulting range. */
2104 if (code == FIX_TRUNC_EXPR
2105 || code == FLOAT_EXPR
2106 || code == BIT_NOT_EXPR
2107 || code == NON_LVALUE_EXPR
2108 || code == CONJ_EXPR)
2110 set_value_range_to_varying (vr);
2114 /* Get value ranges for the operand. For constant operands, create
2115 a new value range with the operand to simplify processing. */
2116 op0 = TREE_OPERAND (expr, 0);
2117 if (TREE_CODE (op0) == SSA_NAME)
2118 vr0 = *(get_value_range (op0));
2119 else if (is_gimple_min_invariant (op0))
2120 set_value_range_to_value (&vr0, op0, NULL);
2122 set_value_range_to_varying (&vr0);
2124 /* If VR0 is UNDEFINED, so is the result. */
2125 if (vr0.type == VR_UNDEFINED)
2127 set_value_range_to_undefined (vr);
2131 /* Refuse to operate on symbolic ranges, or if neither operand is
2132 a pointer or integral type. */
2133 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0))
2134 && !POINTER_TYPE_P (TREE_TYPE (op0)))
2135 || (vr0.type != VR_VARYING
2136 && symbolic_range_p (&vr0)))
2138 set_value_range_to_varying (vr);
2142 /* If the expression involves pointers, we are only interested in
2143 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
2144 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
2149 if (range_is_nonnull (&vr0)
2150 || (tree_expr_nonzero_warnv_p (expr, &sop)
2152 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
2153 else if (range_is_null (&vr0))
2154 set_value_range_to_null (vr, TREE_TYPE (expr));
2156 set_value_range_to_varying (vr);
2161 /* Handle unary expressions on integer ranges. */
2162 if (code == NOP_EXPR || code == CONVERT_EXPR)
2164 tree inner_type = TREE_TYPE (op0);
2165 tree outer_type = TREE_TYPE (expr);
2167 /* If VR0 represents a simple range, then try to convert
2168 the min and max values for the range to the same type
2169 as OUTER_TYPE. If the results compare equal to VR0's
2170 min and max values and the new min is still less than
2171 or equal to the new max, then we can safely use the newly
2172 computed range for EXPR. This allows us to compute
2173 accurate ranges through many casts. */
2174 if ((vr0.type == VR_RANGE
2175 && !overflow_infinity_range_p (&vr0))
2176 || (vr0.type == VR_VARYING
2177 && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type)))
2179 tree new_min, new_max, orig_min, orig_max;
2181 /* Convert the input operand min/max to OUTER_TYPE. If
2182 the input has no range information, then use the min/max
2183 for the input's type. */
2184 if (vr0.type == VR_RANGE)
2191 orig_min = TYPE_MIN_VALUE (inner_type);
2192 orig_max = TYPE_MAX_VALUE (inner_type);
2195 new_min = fold_convert (outer_type, orig_min);
2196 new_max = fold_convert (outer_type, orig_max);
2198 /* Verify the new min/max values are gimple values and
2199 that they compare equal to the original input's
2201 if (is_gimple_val (new_min)
2202 && is_gimple_val (new_max)
2203 && tree_int_cst_equal (new_min, orig_min)
2204 && tree_int_cst_equal (new_max, orig_max)
2205 && (cmp = compare_values (new_min, new_max)) <= 0
2208 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
2213 /* When converting types of different sizes, set the result to
2214 VARYING. Things like sign extensions and precision loss may
2215 change the range. For instance, if x_3 is of type 'long long
2216 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
2217 is impossible to know at compile time whether y_5 will be
2219 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
2220 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
2222 set_value_range_to_varying (vr);
2227 /* Conversion of a VR_VARYING value to a wider type can result
2228 in a usable range. So wait until after we've handled conversions
2229 before dropping the result to VR_VARYING if we had a source
2230 operand that is VR_VARYING. */
2231 if (vr0.type == VR_VARYING)
2233 set_value_range_to_varying (vr);
2237 /* Apply the operation to each end of the range and see what we end
2239 if (code == NEGATE_EXPR
2240 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
2242 /* NEGATE_EXPR flips the range around. We need to treat
2243 TYPE_MIN_VALUE specially. */
2244 if (is_positive_overflow_infinity (vr0.max))
2245 min = negative_overflow_infinity (TREE_TYPE (expr));
2246 else if (is_negative_overflow_infinity (vr0.max))
2247 min = positive_overflow_infinity (TREE_TYPE (expr));
2248 else if (!vrp_val_is_min (vr0.max))
2249 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2250 else if (needs_overflow_infinity (TREE_TYPE (expr)))
2252 if (supports_overflow_infinity (TREE_TYPE (expr))
2253 && !is_overflow_infinity (vr0.min)
2254 && !vrp_val_is_min (vr0.min))
2255 min = positive_overflow_infinity (TREE_TYPE (expr));
2258 set_value_range_to_varying (vr);
2263 min = TYPE_MIN_VALUE (TREE_TYPE (expr));
2265 if (is_positive_overflow_infinity (vr0.min))
2266 max = negative_overflow_infinity (TREE_TYPE (expr));
2267 else if (is_negative_overflow_infinity (vr0.min))
2268 max = positive_overflow_infinity (TREE_TYPE (expr));
2269 else if (!vrp_val_is_min (vr0.min))
2270 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2271 else if (needs_overflow_infinity (TREE_TYPE (expr)))
2273 if (supports_overflow_infinity (TREE_TYPE (expr)))
2274 max = positive_overflow_infinity (TREE_TYPE (expr));
2277 set_value_range_to_varying (vr);
2282 max = TYPE_MIN_VALUE (TREE_TYPE (expr));
2284 else if (code == NEGATE_EXPR
2285 && TYPE_UNSIGNED (TREE_TYPE (expr)))
2287 if (!range_includes_zero_p (&vr0))
2289 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2290 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2294 if (range_is_null (&vr0))
2295 set_value_range_to_null (vr, TREE_TYPE (expr));
2297 set_value_range_to_varying (vr);
2301 else if (code == ABS_EXPR
2302 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
2304 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
2306 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (expr))
2307 && ((vr0.type == VR_RANGE
2308 && vrp_val_is_min (vr0.min))
2309 || (vr0.type == VR_ANTI_RANGE
2310 && !vrp_val_is_min (vr0.min)
2311 && !range_includes_zero_p (&vr0))))
2313 set_value_range_to_varying (vr);
2317 /* ABS_EXPR may flip the range around, if the original range
2318 included negative values. */
2319 if (is_overflow_infinity (vr0.min))
2320 min = positive_overflow_infinity (TREE_TYPE (expr));
2321 else if (!vrp_val_is_min (vr0.min))
2322 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2323 else if (!needs_overflow_infinity (TREE_TYPE (expr)))
2324 min = TYPE_MAX_VALUE (TREE_TYPE (expr));
2325 else if (supports_overflow_infinity (TREE_TYPE (expr)))
2326 min = positive_overflow_infinity (TREE_TYPE (expr));
2329 set_value_range_to_varying (vr);
2333 if (is_overflow_infinity (vr0.max))
2334 max = positive_overflow_infinity (TREE_TYPE (expr));
2335 else if (!vrp_val_is_min (vr0.max))
2336 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2337 else if (!needs_overflow_infinity (TREE_TYPE (expr)))
2338 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
2339 else if (supports_overflow_infinity (TREE_TYPE (expr)))
2340 max = positive_overflow_infinity (TREE_TYPE (expr));
2343 set_value_range_to_varying (vr);
2347 cmp = compare_values (min, max);
2349 /* If a VR_ANTI_RANGEs contains zero, then we have
2350 ~[-INF, min(MIN, MAX)]. */
2351 if (vr0.type == VR_ANTI_RANGE)
2353 if (range_includes_zero_p (&vr0))
2355 /* Take the lower of the two values. */
2359 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
2360 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
2361 flag_wrapv is set and the original anti-range doesn't include
2362 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
2363 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr)))
2365 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
2367 min = (vr0.min != type_min_value
2368 ? int_const_binop (PLUS_EXPR, type_min_value,
2369 integer_one_node, 0)
2374 if (overflow_infinity_range_p (&vr0))
2375 min = negative_overflow_infinity (TREE_TYPE (expr));
2377 min = TYPE_MIN_VALUE (TREE_TYPE (expr));
2382 /* All else has failed, so create the range [0, INF], even for
2383 flag_wrapv since TYPE_MIN_VALUE is in the original
2385 vr0.type = VR_RANGE;
2386 min = build_int_cst (TREE_TYPE (expr), 0);
2387 if (needs_overflow_infinity (TREE_TYPE (expr)))
2389 if (supports_overflow_infinity (TREE_TYPE (expr)))
2390 max = positive_overflow_infinity (TREE_TYPE (expr));
2393 set_value_range_to_varying (vr);
2398 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
2402 /* If the range contains zero then we know that the minimum value in the
2403 range will be zero. */
2404 else if (range_includes_zero_p (&vr0))
2408 min = build_int_cst (TREE_TYPE (expr), 0);
2412 /* If the range was reversed, swap MIN and MAX. */
2423 /* Otherwise, operate on each end of the range. */
2424 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2425 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2427 if (needs_overflow_infinity (TREE_TYPE (expr)))
2429 gcc_assert (code != NEGATE_EXPR && code != ABS_EXPR);
2431 /* If both sides have overflowed, we don't know
2433 if ((is_overflow_infinity (vr0.min)
2434 || TREE_OVERFLOW (min))
2435 && (is_overflow_infinity (vr0.max)
2436 || TREE_OVERFLOW (max)))
2438 set_value_range_to_varying (vr);
2442 if (is_overflow_infinity (vr0.min))
2444 else if (TREE_OVERFLOW (min))
2446 if (supports_overflow_infinity (TREE_TYPE (expr)))
2447 min = (tree_int_cst_sgn (min) >= 0
2448 ? positive_overflow_infinity (TREE_TYPE (min))
2449 : negative_overflow_infinity (TREE_TYPE (min)));
2452 set_value_range_to_varying (vr);
2457 if (is_overflow_infinity (vr0.max))
2459 else if (TREE_OVERFLOW (max))
2461 if (supports_overflow_infinity (TREE_TYPE (expr)))
2462 max = (tree_int_cst_sgn (max) >= 0
2463 ? positive_overflow_infinity (TREE_TYPE (max))
2464 : negative_overflow_infinity (TREE_TYPE (max)));
2467 set_value_range_to_varying (vr);
2474 cmp = compare_values (min, max);
2475 if (cmp == -2 || cmp == 1)
2477 /* If the new range has its limits swapped around (MIN > MAX),
2478 then the operation caused one of them to wrap around, mark
2479 the new range VARYING. */
2480 set_value_range_to_varying (vr);
2483 set_value_range (vr, vr0.type, min, max, NULL);
2487 /* Extract range information from a conditional expression EXPR based on
2488 the ranges of each of its operands and the expression code. */
2491 extract_range_from_cond_expr (value_range_t *vr, tree expr)
2494 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2495 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2497 /* Get value ranges for each operand. For constant operands, create
2498 a new value range with the operand to simplify processing. */
2499 op0 = COND_EXPR_THEN (expr);
2500 if (TREE_CODE (op0) == SSA_NAME)
2501 vr0 = *(get_value_range (op0));
2502 else if (is_gimple_min_invariant (op0))
2503 set_value_range_to_value (&vr0, op0, NULL);
2505 set_value_range_to_varying (&vr0);
2507 op1 = COND_EXPR_ELSE (expr);
2508 if (TREE_CODE (op1) == SSA_NAME)
2509 vr1 = *(get_value_range (op1));
2510 else if (is_gimple_min_invariant (op1))
2511 set_value_range_to_value (&vr1, op1, NULL);
2513 set_value_range_to_varying (&vr1);
2515 /* The resulting value range is the union of the operand ranges */
2516 vrp_meet (&vr0, &vr1);
2517 copy_value_range (vr, &vr0);
2521 /* Extract range information from a comparison expression EXPR based
2522 on the range of its operand and the expression code. */
2525 extract_range_from_comparison (value_range_t *vr, tree expr)
2528 tree val = vrp_evaluate_conditional_warnv (expr, false, &sop);
2530 /* A disadvantage of using a special infinity as an overflow
2531 representation is that we lose the ability to record overflow
2532 when we don't have an infinity. So we have to ignore a result
2533 which relies on overflow. */
2535 if (val && !is_overflow_infinity (val) && !sop)
2537 /* Since this expression was found on the RHS of an assignment,
2538 its type may be different from _Bool. Convert VAL to EXPR's
2540 val = fold_convert (TREE_TYPE (expr), val);
2541 if (is_gimple_min_invariant (val))
2542 set_value_range_to_value (vr, val, vr->equiv);
2544 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
2547 /* The result of a comparison is always true or false. */
2548 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
2552 /* Try to compute a useful range out of expression EXPR and store it
2556 extract_range_from_expr (value_range_t *vr, tree expr)
2558 enum tree_code code = TREE_CODE (expr);
2560 if (code == ASSERT_EXPR)
2561 extract_range_from_assert (vr, expr);
2562 else if (code == SSA_NAME)
2563 extract_range_from_ssa_name (vr, expr);
2564 else if (TREE_CODE_CLASS (code) == tcc_binary
2565 || code == TRUTH_ANDIF_EXPR
2566 || code == TRUTH_ORIF_EXPR
2567 || code == TRUTH_AND_EXPR
2568 || code == TRUTH_OR_EXPR
2569 || code == TRUTH_XOR_EXPR)
2570 extract_range_from_binary_expr (vr, expr);
2571 else if (TREE_CODE_CLASS (code) == tcc_unary)
2572 extract_range_from_unary_expr (vr, expr);
2573 else if (code == COND_EXPR)
2574 extract_range_from_cond_expr (vr, expr);
2575 else if (TREE_CODE_CLASS (code) == tcc_comparison)
2576 extract_range_from_comparison (vr, expr);
2577 else if (is_gimple_min_invariant (expr))
2578 set_value_range_to_value (vr, expr, NULL);
2580 set_value_range_to_varying (vr);
2582 /* If we got a varying range from the tests above, try a final
2583 time to derive a nonnegative or nonzero range. This time
2584 relying primarily on generic routines in fold in conjunction
2586 if (vr->type == VR_VARYING)
2590 if (INTEGRAL_TYPE_P (TREE_TYPE (expr))
2591 && vrp_expr_computes_nonnegative (expr, &sop))
2592 set_value_range_to_nonnegative (vr, TREE_TYPE (expr),
2593 sop || is_overflow_infinity (expr));
2594 else if (vrp_expr_computes_nonzero (expr, &sop)
2596 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
2600 /* Given a range VR, a LOOP and a variable VAR, determine whether it
2601 would be profitable to adjust VR using scalar evolution information
2602 for VAR. If so, update VR with the new limits. */
2605 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
2608 tree init, step, chrec, tmin, tmax, min, max, type;
2609 enum ev_direction dir;
2611 /* TODO. Don't adjust anti-ranges. An anti-range may provide
2612 better opportunities than a regular range, but I'm not sure. */
2613 if (vr->type == VR_ANTI_RANGE)
2616 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
2617 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
2620 init = initial_condition_in_loop_num (chrec, loop->num);
2621 step = evolution_part_in_loop_num (chrec, loop->num);
2623 /* If STEP is symbolic, we can't know whether INIT will be the
2624 minimum or maximum value in the range. Also, unless INIT is
2625 a simple expression, compare_values and possibly other functions
2626 in tree-vrp won't be able to handle it. */
2627 if (step == NULL_TREE
2628 || !is_gimple_min_invariant (step)
2629 || !valid_value_p (init))
2632 dir = scev_direction (chrec);
2633 if (/* Do not adjust ranges if we do not know whether the iv increases
2634 or decreases, ... */
2635 dir == EV_DIR_UNKNOWN
2636 /* ... or if it may wrap. */
2637 || scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec),
2641 /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of
2642 negative_overflow_infinity and positive_overflow_infinity,
2643 because we have concluded that the loop probably does not
2646 type = TREE_TYPE (var);
2647 if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type))
2648 tmin = lower_bound_in_type (type, type);
2650 tmin = TYPE_MIN_VALUE (type);
2651 if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type))
2652 tmax = upper_bound_in_type (type, type);
2654 tmax = TYPE_MAX_VALUE (type);
2656 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2661 /* For VARYING or UNDEFINED ranges, just about anything we get
2662 from scalar evolutions should be better. */
2664 if (dir == EV_DIR_DECREASES)
2669 /* If we would create an invalid range, then just assume we
2670 know absolutely nothing. This may be over-conservative,
2671 but it's clearly safe, and should happen only in unreachable
2672 parts of code, or for invalid programs. */
2673 if (compare_values (min, max) == 1)
2676 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2678 else if (vr->type == VR_RANGE)
2683 if (dir == EV_DIR_DECREASES)
2685 /* INIT is the maximum value. If INIT is lower than VR->MAX
2686 but no smaller than VR->MIN, set VR->MAX to INIT. */
2687 if (compare_values (init, max) == -1)
2691 /* If we just created an invalid range with the minimum
2692 greater than the maximum, we fail conservatively.
2693 This should happen only in unreachable
2694 parts of code, or for invalid programs. */
2695 if (compare_values (min, max) == 1)
2701 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2702 if (compare_values (init, min) == 1)
2706 /* Again, avoid creating invalid range by failing. */
2707 if (compare_values (min, max) == 1)
2712 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2717 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2719 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2720 all the values in the ranges.
2722 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2724 - Return NULL_TREE if it is not always possible to determine the
2725 value of the comparison.
2727 Also set *STRICT_OVERFLOW_P to indicate whether a range with an
2728 overflow infinity was used in the test. */
2732 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1,
2733 bool *strict_overflow_p)
2735 /* VARYING or UNDEFINED ranges cannot be compared. */
2736 if (vr0->type == VR_VARYING
2737 || vr0->type == VR_UNDEFINED
2738 || vr1->type == VR_VARYING
2739 || vr1->type == VR_UNDEFINED)
2742 /* Anti-ranges need to be handled separately. */
2743 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
2745 /* If both are anti-ranges, then we cannot compute any
2747 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
2750 /* These comparisons are never statically computable. */
2757 /* Equality can be computed only between a range and an
2758 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2759 if (vr0->type == VR_RANGE)
2761 /* To simplify processing, make VR0 the anti-range. */
2762 value_range_t *tmp = vr0;
2767 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
2769 if (compare_values_warnv (vr0->min, vr1->min, strict_overflow_p) == 0
2770 && compare_values_warnv (vr0->max, vr1->max, strict_overflow_p) == 0)
2771 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2776 if (!usable_range_p (vr0, strict_overflow_p)
2777 || !usable_range_p (vr1, strict_overflow_p))
2780 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2781 operands around and change the comparison code. */
2782 if (comp == GT_EXPR || comp == GE_EXPR)
2785 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
2791 if (comp == EQ_EXPR)
2793 /* Equality may only be computed if both ranges represent
2794 exactly one value. */
2795 if (compare_values_warnv (vr0->min, vr0->max, strict_overflow_p) == 0
2796 && compare_values_warnv (vr1->min, vr1->max, strict_overflow_p) == 0)
2798 int cmp_min = compare_values_warnv (vr0->min, vr1->min,
2800 int cmp_max = compare_values_warnv (vr0->max, vr1->max,
2802 if (cmp_min == 0 && cmp_max == 0)
2803 return boolean_true_node;
2804 else if (cmp_min != -2 && cmp_max != -2)
2805 return boolean_false_node;
2807 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2808 else if (compare_values_warnv (vr0->min, vr1->max,
2809 strict_overflow_p) == 1
2810 || compare_values_warnv (vr1->min, vr0->max,
2811 strict_overflow_p) == 1)
2812 return boolean_false_node;
2816 else if (comp == NE_EXPR)
2820 /* If VR0 is completely to the left or completely to the right
2821 of VR1, they are always different. Notice that we need to
2822 make sure that both comparisons yield similar results to
2823 avoid comparing values that cannot be compared at
2825 cmp1 = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
2826 cmp2 = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
2827 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
2828 return boolean_true_node;
2830 /* If VR0 and VR1 represent a single value and are identical,
2832 else if (compare_values_warnv (vr0->min, vr0->max,
2833 strict_overflow_p) == 0
2834 && compare_values_warnv (vr1->min, vr1->max,
2835 strict_overflow_p) == 0
2836 && compare_values_warnv (vr0->min, vr1->min,
2837 strict_overflow_p) == 0
2838 && compare_values_warnv (vr0->max, vr1->max,
2839 strict_overflow_p) == 0)
2840 return boolean_false_node;
2842 /* Otherwise, they may or may not be different. */
2846 else if (comp == LT_EXPR || comp == LE_EXPR)
2850 /* If VR0 is to the left of VR1, return true. */
2851 tst = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
2852 if ((comp == LT_EXPR && tst == -1)
2853 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2855 if (overflow_infinity_range_p (vr0)
2856 || overflow_infinity_range_p (vr1))
2857 *strict_overflow_p = true;
2858 return boolean_true_node;
2861 /* If VR0 is to the right of VR1, return false. */
2862 tst = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
2863 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2864 || (comp == LE_EXPR && tst == 1))
2866 if (overflow_infinity_range_p (vr0)
2867 || overflow_infinity_range_p (vr1))
2868 *strict_overflow_p = true;
2869 return boolean_false_node;
2872 /* Otherwise, we don't know. */
2880 /* Given a value range VR, a value VAL and a comparison code COMP, return
2881 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2882 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2883 always returns false. Return NULL_TREE if it is not always
2884 possible to determine the value of the comparison. Also set
2885 *STRICT_OVERFLOW_P to indicate whether a range with an overflow
2886 infinity was used in the test. */
2889 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val,
2890 bool *strict_overflow_p)
2892 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2895 /* Anti-ranges need to be handled separately. */
2896 if (vr->type == VR_ANTI_RANGE)
2898 /* For anti-ranges, the only predicates that we can compute at
2899 compile time are equality and inequality. */
2906 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2907 if (value_inside_range (val, vr) == 1)
2908 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2913 if (!usable_range_p (vr, strict_overflow_p))
2916 if (comp == EQ_EXPR)
2918 /* EQ_EXPR may only be computed if VR represents exactly
2920 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0)
2922 int cmp = compare_values_warnv (vr->min, val, strict_overflow_p);
2924 return boolean_true_node;
2925 else if (cmp == -1 || cmp == 1 || cmp == 2)
2926 return boolean_false_node;
2928 else if (compare_values_warnv (val, vr->min, strict_overflow_p) == -1
2929 || compare_values_warnv (vr->max, val, strict_overflow_p) == -1)
2930 return boolean_false_node;
2934 else if (comp == NE_EXPR)
2936 /* If VAL is not inside VR, then they are always different. */
2937 if (compare_values_warnv (vr->max, val, strict_overflow_p) == -1
2938 || compare_values_warnv (vr->min, val, strict_overflow_p) == 1)
2939 return boolean_true_node;
2941 /* If VR represents exactly one value equal to VAL, then return
2943 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0
2944 && compare_values_warnv (vr->min, val, strict_overflow_p) == 0)
2945 return boolean_false_node;
2947 /* Otherwise, they may or may not be different. */
2950 else if (comp == LT_EXPR || comp == LE_EXPR)
2954 /* If VR is to the left of VAL, return true. */
2955 tst = compare_values_warnv (vr->max, val, strict_overflow_p);
2956 if ((comp == LT_EXPR && tst == -1)
2957 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2959 if (overflow_infinity_range_p (vr))
2960 *strict_overflow_p = true;
2961 return boolean_true_node;
2964 /* If VR is to the right of VAL, return false. */
2965 tst = compare_values_warnv (vr->min, val, strict_overflow_p);
2966 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2967 || (comp == LE_EXPR && tst == 1))
2969 if (overflow_infinity_range_p (vr))
2970 *strict_overflow_p = true;
2971 return boolean_false_node;
2974 /* Otherwise, we don't know. */
2977 else if (comp == GT_EXPR || comp == GE_EXPR)
2981 /* If VR is to the right of VAL, return true. */
2982 tst = compare_values_warnv (vr->min, val, strict_overflow_p);
2983 if ((comp == GT_EXPR && tst == 1)
2984 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
2986 if (overflow_infinity_range_p (vr))
2987 *strict_overflow_p = true;
2988 return boolean_true_node;
2991 /* If VR is to the left of VAL, return false. */
2992 tst = compare_values_warnv (vr->max, val, strict_overflow_p);
2993 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
2994 || (comp == GE_EXPR && tst == -1))
2996 if (overflow_infinity_range_p (vr))
2997 *strict_overflow_p = true;
2998 return boolean_false_node;
3001 /* Otherwise, we don't know. */
3009 /* Debugging dumps. */
3011 void dump_value_range (FILE *, value_range_t *);
3012 void debug_value_range (value_range_t *);
3013 void dump_all_value_ranges (FILE *);
3014 void debug_all_value_ranges (void);
3015 void dump_vr_equiv (FILE *, bitmap);
3016 void debug_vr_equiv (bitmap);
3019 /* Dump value range VR to FILE. */
3022 dump_value_range (FILE *file, value_range_t *vr)
3025 fprintf (file, "[]");
3026 else if (vr->type == VR_UNDEFINED)
3027 fprintf (file, "UNDEFINED");
3028 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
3030 tree type = TREE_TYPE (vr->min);
3032 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
3034 if (is_negative_overflow_infinity (vr->min))
3035 fprintf (file, "-INF(OVF)");
3036 else if (INTEGRAL_TYPE_P (type)
3037 && !TYPE_UNSIGNED (type)
3038 && vrp_val_is_min (vr->min))
3039 fprintf (file, "-INF");
3041 print_generic_expr (file, vr->min, 0);
3043 fprintf (file, ", ");
3045 if (is_positive_overflow_infinity (vr->max))
3046 fprintf (file, "+INF(OVF)");
3047 else if (INTEGRAL_TYPE_P (type)
3048 && vrp_val_is_max (vr->max))
3049 fprintf (file, "+INF");
3051 print_generic_expr (file, vr->max, 0);
3053 fprintf (file, "]");
3060 fprintf (file, " EQUIVALENCES: { ");
3062 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
3064 print_generic_expr (file, ssa_name (i), 0);
3065 fprintf (file, " ");
3069 fprintf (file, "} (%u elements)", c);
3072 else if (vr->type == VR_VARYING)
3073 fprintf (file, "VARYING");
3075 fprintf (file, "INVALID RANGE");
3079 /* Dump value range VR to stderr. */
3082 debug_value_range (value_range_t *vr)
3084 dump_value_range (stderr, vr);
3085 fprintf (stderr, "\n");
3089 /* Dump value ranges of all SSA_NAMEs to FILE. */
3092 dump_all_value_ranges (FILE *file)
3096 for (i = 0; i < num_ssa_names; i++)
3100 print_generic_expr (file, ssa_name (i), 0);
3101 fprintf (file, ": ");
3102 dump_value_range (file, vr_value[i]);
3103 fprintf (file, "\n");
3107 fprintf (file, "\n");
3111 /* Dump all value ranges to stderr. */
3114 debug_all_value_ranges (void)
3116 dump_all_value_ranges (stderr);
3120 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
3121 create a new SSA name N and return the assertion assignment
3122 'V = ASSERT_EXPR <V, V OP W>'. */
3125 build_assert_expr_for (tree cond, tree v)
3129 gcc_assert (TREE_CODE (v) == SSA_NAME);
3130 n = duplicate_ssa_name (v, NULL_TREE);
3132 if (COMPARISON_CLASS_P (cond))
3134 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
3135 assertion = build_gimple_modify_stmt (n, a);
3137 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
3139 /* Given !V, build the assignment N = false. */
3140 tree op0 = TREE_OPERAND (cond, 0);
3141 gcc_assert (op0 == v);
3142 assertion = build_gimple_modify_stmt (n, boolean_false_node);
3144 else if (TREE_CODE (cond) == SSA_NAME)
3146 /* Given V, build the assignment N = true. */
3147 gcc_assert (v == cond);
3148 assertion = build_gimple_modify_stmt (n, boolean_true_node);
3153 SSA_NAME_DEF_STMT (n) = assertion;
3155 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
3156 operand of the ASSERT_EXPR. Register the new name and the old one
3157 in the replacement table so that we can fix the SSA web after
3158 adding all the ASSERT_EXPRs. */
3159 register_new_name_mapping (n, v);
3165 /* Return false if EXPR is a predicate expression involving floating
3169 fp_predicate (tree expr)
3171 return (COMPARISON_CLASS_P (expr)
3172 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
3176 /* If the range of values taken by OP can be inferred after STMT executes,
3177 return the comparison code (COMP_CODE_P) and value (VAL_P) that
3178 describes the inferred range. Return true if a range could be
3182 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
3185 *comp_code_p = ERROR_MARK;
3187 /* Do not attempt to infer anything in names that flow through
3189 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
3192 /* Similarly, don't infer anything from statements that may throw
3194 if (tree_could_throw_p (stmt))
3197 /* If STMT is the last statement of a basic block with no
3198 successors, there is no point inferring anything about any of its
3199 operands. We would not be able to find a proper insertion point
3200 for the assertion, anyway. */
3201 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
3204 /* We can only assume that a pointer dereference will yield
3205 non-NULL if -fdelete-null-pointer-checks is enabled. */
3206 if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op)))
3208 unsigned num_uses, num_loads, num_stores;
3210 count_uses_and_derefs (op, stmt, &num_uses, &num_loads, &num_stores);
3211 if (num_loads + num_stores > 0)
3213 *val_p = build_int_cst (TREE_TYPE (op), 0);
3214 *comp_code_p = NE_EXPR;
3223 void dump_asserts_for (FILE *, tree);
3224 void debug_asserts_for (tree);
3225 void dump_all_asserts (FILE *);
3226 void debug_all_asserts (void);
3228 /* Dump all the registered assertions for NAME to FILE. */
3231 dump_asserts_for (FILE *file, tree name)
3235 fprintf (file, "Assertions to be inserted for ");
3236 print_generic_expr (file, name, 0);
3237 fprintf (file, "\n");
3239 loc = asserts_for[SSA_NAME_VERSION (name)];
3242 fprintf (file, "\t");
3243 print_generic_expr (file, bsi_stmt (loc->si), 0);
3244 fprintf (file, "\n\tBB #%d", loc->bb->index);
3247 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
3248 loc->e->dest->index);
3249 dump_edge_info (file, loc->e, 0);
3251 fprintf (file, "\n\tPREDICATE: ");
3252 print_generic_expr (file, name, 0);
3253 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
3254 print_generic_expr (file, loc->val, 0);
3255 fprintf (file, "\n\n");
3259 fprintf (file, "\n");
3263 /* Dump all the registered assertions for NAME to stderr. */
3266 debug_asserts_for (tree name)
3268 dump_asserts_for (stderr, name);
3272 /* Dump all the registered assertions for all the names to FILE. */
3275 dump_all_asserts (FILE *file)
3280 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
3281 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3282 dump_asserts_for (file, ssa_name (i));
3283 fprintf (file, "\n");
3287 /* Dump all the registered assertions for all the names to stderr. */
3290 debug_all_asserts (void)
3292 dump_all_asserts (stderr);
3296 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
3297 'NAME COMP_CODE VAL' at a location that dominates block BB or
3298 E->DEST, then register this location as a possible insertion point
3299 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
3301 BB, E and SI provide the exact insertion point for the new
3302 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
3303 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
3304 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
3305 must not be NULL. */
3308 register_new_assert_for (tree name,
3309 enum tree_code comp_code,
3313 block_stmt_iterator si)
3315 assert_locus_t n, loc, last_loc;
3317 basic_block dest_bb;
3319 #if defined ENABLE_CHECKING
3320 gcc_assert (bb == NULL || e == NULL);
3323 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
3324 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
3327 /* The new assertion A will be inserted at BB or E. We need to
3328 determine if the new location is dominated by a previously
3329 registered location for A. If we are doing an edge insertion,
3330 assume that A will be inserted at E->DEST. Note that this is not
3333 If E is a critical edge, it will be split. But even if E is
3334 split, the new block will dominate the same set of blocks that
3337 The reverse, however, is not true, blocks dominated by E->DEST
3338 will not be dominated by the new block created to split E. So,
3339 if the insertion location is on a critical edge, we will not use
3340 the new location to move another assertion previously registered
3341 at a block dominated by E->DEST. */
3342 dest_bb = (bb) ? bb : e->dest;
3344 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
3345 VAL at a block dominating DEST_BB, then we don't need to insert a new
3346 one. Similarly, if the same assertion already exists at a block
3347 dominated by DEST_BB and the new location is not on a critical
3348 edge, then update the existing location for the assertion (i.e.,
3349 move the assertion up in the dominance tree).
3351 Note, this is implemented as a simple linked list because there
3352 should not be more than a handful of assertions registered per
3353 name. If this becomes a performance problem, a table hashed by
3354 COMP_CODE and VAL could be implemented. */
3355 loc = asserts_for[SSA_NAME_VERSION (name)];
3360 if (loc->comp_code == comp_code
3362 || operand_equal_p (loc->val, val, 0)))
3364 /* If the assertion NAME COMP_CODE VAL has already been
3365 registered at a basic block that dominates DEST_BB, then
3366 we don't need to insert the same assertion again. Note
3367 that we don't check strict dominance here to avoid
3368 replicating the same assertion inside the same basic
3369 block more than once (e.g., when a pointer is
3370 dereferenced several times inside a block).
3372 An exception to this rule are edge insertions. If the
3373 new assertion is to be inserted on edge E, then it will
3374 dominate all the other insertions that we may want to
3375 insert in DEST_BB. So, if we are doing an edge
3376 insertion, don't do this dominance check. */
3378 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
3381 /* Otherwise, if E is not a critical edge and DEST_BB
3382 dominates the existing location for the assertion, move
3383 the assertion up in the dominance tree by updating its
3384 location information. */
3385 if ((e == NULL || !EDGE_CRITICAL_P (e))
3386 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
3395 /* Update the last node of the list and move to the next one. */
3400 /* If we didn't find an assertion already registered for
3401 NAME COMP_CODE VAL, add a new one at the end of the list of
3402 assertions associated with NAME. */
3403 n = XNEW (struct assert_locus_d);
3407 n->comp_code = comp_code;
3414 asserts_for[SSA_NAME_VERSION (name)] = n;
3416 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
3419 /* COND is a predicate which uses NAME. Extract a suitable test code
3420 and value and store them into *CODE_P and *VAL_P so the predicate
3421 is normalized to NAME *CODE_P *VAL_P.
3423 If no extraction was possible, return FALSE, otherwise return TRUE.
3425 If INVERT is true, then we invert the result stored into *CODE_P. */
3428 extract_code_and_val_from_cond (tree name, tree cond, bool invert,
3429 enum tree_code *code_p, tree *val_p)
3431 enum tree_code comp_code;
3434 /* Predicates may be a single SSA name or NAME OP VAL. */
3437 /* If the predicate is a name, it must be NAME, in which
3438 case we create the predicate NAME == true or
3439 NAME == false accordingly. */
3440 comp_code = EQ_EXPR;
3441 val = invert ? boolean_false_node : boolean_true_node;
3445 /* Otherwise, we have a comparison of the form NAME COMP VAL
3446 or VAL COMP NAME. */
3447 if (name == TREE_OPERAND (cond, 1))
3449 /* If the predicate is of the form VAL COMP NAME, flip
3450 COMP around because we need to register NAME as the
3451 first operand in the predicate. */
3452 comp_code = swap_tree_comparison (TREE_CODE (cond));
3453 val = TREE_OPERAND (cond, 0);
3457 /* The comparison is of the form NAME COMP VAL, so the
3458 comparison code remains unchanged. */
3459 comp_code = TREE_CODE (cond);
3460 val = TREE_OPERAND (cond, 1);
3463 /* Invert the comparison code as necessary. */
3465 comp_code = invert_tree_comparison (comp_code, 0);
3467 /* VRP does not handle float types. */
3468 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)))
3471 /* Do not register always-false predicates.
3472 FIXME: this works around a limitation in fold() when dealing with
3473 enumerations. Given 'enum { N1, N2 } x;', fold will not
3474 fold 'if (x > N2)' to 'if (0)'. */
3475 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
3476 && INTEGRAL_TYPE_P (TREE_TYPE (val)))
3478 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
3479 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
3481 if (comp_code == GT_EXPR
3483 || compare_values (val, max) == 0))
3486 if (comp_code == LT_EXPR
3488 || compare_values (val, min) == 0))
3492 *code_p = comp_code;
3497 /* OP is an operand of a truth value expression which is known to have
3498 a particular value. Register any asserts for OP and for any
3499 operands in OP's defining statement.
3501 If CODE is EQ_EXPR, then we want to register OP is zero (false),
3502 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
3505 register_edge_assert_for_1 (tree op, enum tree_code code,
3506 edge e, block_stmt_iterator bsi)
3508 bool retval = false;
3509 tree op_def, rhs, val;
3511 /* We only care about SSA_NAMEs. */
3512 if (TREE_CODE (op) != SSA_NAME)
3515 /* We know that OP will have a zero or nonzero value. If OP is used
3516 more than once go ahead and register an assert for OP.
3518 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
3519 it will always be set for OP (because OP is used in a COND_EXPR in
3521 if (!has_single_use (op))
3523 val = build_int_cst (TREE_TYPE (op), 0);
3524 register_new_assert_for (op, code, val, NULL, e, bsi);
3528 /* Now look at how OP is set. If it's set from a comparison,
3529 a truth operation or some bit operations, then we may be able
3530 to register information about the operands of that assignment. */
3531 op_def = SSA_NAME_DEF_STMT (op);
3532 if (TREE_CODE (op_def) != GIMPLE_MODIFY_STMT)
3535 rhs = GIMPLE_STMT_OPERAND (op_def, 1);
3537 if (COMPARISON_CLASS_P (rhs))
3539 bool invert = (code == EQ_EXPR ? true : false);
3540 tree op0 = TREE_OPERAND (rhs, 0);
3541 tree op1 = TREE_OPERAND (rhs, 1);
3543 /* Conditionally register an assert for each SSA_NAME in the
3545 if (TREE_CODE (op0) == SSA_NAME
3546 && !has_single_use (op0)
3547 && extract_code_and_val_from_cond (op0, rhs,
3548 invert, &code, &val))
3550 register_new_assert_for (op0, code, val, NULL, e, bsi);
3554 /* Similarly for the second operand of the comparison. */
3555 if (TREE_CODE (op1) == SSA_NAME
3556 && !has_single_use (op1)
3557 && extract_code_and_val_from_cond (op1, rhs,
3558 invert, &code, &val))
3560 register_new_assert_for (op1, code, val, NULL, e, bsi);
3564 else if ((code == NE_EXPR
3565 && (TREE_CODE (rhs) == TRUTH_AND_EXPR
3566 || TREE_CODE (rhs) == BIT_AND_EXPR))
3568 && (TREE_CODE (rhs) == TRUTH_OR_EXPR
3569 || TREE_CODE (rhs) == BIT_IOR_EXPR)))
3571 /* Recurse on each operand. */
3572 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3574 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 1),
3577 else if (TREE_CODE (rhs) == TRUTH_NOT_EXPR)
3579 /* Recurse, flipping CODE. */
3580 code = invert_tree_comparison (code, false);
3581 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3584 else if (TREE_CODE (rhs) == SSA_NAME)
3586 /* Recurse through the copy. */
3587 retval |= register_edge_assert_for_1 (rhs, code, e, bsi);
3589 else if (TREE_CODE (rhs) == NOP_EXPR
3590 || TREE_CODE (rhs) == CONVERT_EXPR
3591 || TREE_CODE (rhs) == NON_LVALUE_EXPR)
3593 /* Recurse through the type conversion. */
3594 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3601 /* Try to register an edge assertion for SSA name NAME on edge E for
3602 the condition COND contributing to the conditional jump pointed to by SI.
3603 Return true if an assertion for NAME could be registered. */
3606 register_edge_assert_for (tree name, edge e, block_stmt_iterator si, tree cond)
3609 enum tree_code comp_code;
3610 bool retval = false;
3611 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
3613 /* Do not attempt to infer anything in names that flow through
3615 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
3618 if (!extract_code_and_val_from_cond (name, cond, is_else_edge,
3622 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
3623 reachable from E. */
3624 if (TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
3626 register_new_assert_for (name, comp_code, val, NULL, e, si);
3630 /* If COND is effectively an equality test of an SSA_NAME against
3631 the value zero or one, then we may be able to assert values
3632 for SSA_NAMEs which flow into COND. */
3634 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
3635 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
3636 have nonzero value. */
3637 if (((comp_code == EQ_EXPR && integer_onep (val))
3638 || (comp_code == NE_EXPR && integer_zerop (val))))
3640 tree def_stmt = SSA_NAME_DEF_STMT (name);
3642 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3643 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_AND_EXPR
3644 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_AND_EXPR))
3646 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3647 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3648 retval |= register_edge_assert_for_1 (op0, NE_EXPR, e, si);
3649 retval |= register_edge_assert_for_1 (op1, NE_EXPR, e, si);
3653 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
3654 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
3656 if (((comp_code == EQ_EXPR && integer_zerop (val))
3657 || (comp_code == NE_EXPR && integer_onep (val))))
3659 tree def_stmt = SSA_NAME_DEF_STMT (name);
3661 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3662 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_OR_EXPR
3663 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_IOR_EXPR))
3665 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3666 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3667 retval |= register_edge_assert_for_1 (op0, EQ_EXPR, e, si);
3668 retval |= register_edge_assert_for_1 (op1, EQ_EXPR, e, si);
3676 static bool find_assert_locations (basic_block bb);
3678 /* Determine whether the outgoing edges of BB should receive an
3679 ASSERT_EXPR for each of the operands of BB's LAST statement.
3680 The last statement of BB must be a COND_EXPR.
3682 If any of the sub-graphs rooted at BB have an interesting use of
3683 the predicate operands, an assert location node is added to the
3684 list of assertions for the corresponding operands. */
3687 find_conditional_asserts (basic_block bb, tree last)
3690 block_stmt_iterator bsi;
3696 need_assert = false;
3697 bsi = bsi_for_stmt (last);
3699 /* Look for uses of the operands in each of the sub-graphs
3700 rooted at BB. We need to check each of the outgoing edges
3701 separately, so that we know what kind of ASSERT_EXPR to
3703 FOR_EACH_EDGE (e, ei, bb->succs)
3708 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
3709 Otherwise, when we finish traversing each of the sub-graphs, we
3710 won't know whether the variables were found in the sub-graphs or
3711 if they had been found in a block upstream from BB.
3713 This is actually a bad idea is some cases, particularly jump
3714 threading. Consider a CFG like the following:
3724 Assume that one or more operands in the conditional at the
3725 end of block 0 are used in a conditional in block 2, but not
3726 anywhere in block 1. In this case we will not insert any
3727 assert statements in block 1, which may cause us to miss
3728 opportunities to optimize, particularly for jump threading. */
3729 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3730 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3732 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3733 to determine if any of the operands in the conditional
3734 predicate are used. */
3736 need_assert |= find_assert_locations (e->dest);
3738 /* Register the necessary assertions for each operand in the
3739 conditional predicate. */
3740 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3741 need_assert |= register_edge_assert_for (op, e, bsi,
3742 COND_EXPR_COND (last));
3745 /* Finally, indicate that we have found the operands in the
3747 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3748 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3753 /* Compare two case labels sorting first by the destination label uid
3754 and then by the case value. */
3757 compare_case_labels (const void *p1, const void *p2)
3759 tree case1 = *(tree *)p1;
3760 tree case2 = *(tree *)p2;
3761 unsigned int uid1 = DECL_UID (CASE_LABEL (case1));
3762 unsigned int uid2 = DECL_UID (CASE_LABEL (case2));
3766 else if (uid1 == uid2)
3768 /* Make sure the default label is first in a group. */
3769 if (!CASE_LOW (case1))
3771 else if (!CASE_LOW (case2))
3774 return tree_int_cst_compare (CASE_LOW (case1), CASE_LOW (case2));
3780 /* Determine whether the outgoing edges of BB should receive an
3781 ASSERT_EXPR for each of the operands of BB's LAST statement.
3782 The last statement of BB must be a SWITCH_EXPR.
3784 If any of the sub-graphs rooted at BB have an interesting use of
3785 the predicate operands, an assert location node is added to the
3786 list of assertions for the corresponding operands. */
3789 find_switch_asserts (basic_block bb, tree last)
3792 block_stmt_iterator bsi;
3795 tree vec = SWITCH_LABELS (last), vec2;
3796 size_t n = TREE_VEC_LENGTH (vec);
3799 need_assert = false;
3800 bsi = bsi_for_stmt (last);
3801 op = TREE_OPERAND (last, 0);
3802 if (TREE_CODE (op) != SSA_NAME)
3805 /* Build a vector of case labels sorted by destination label. */
3806 vec2 = make_tree_vec (n);
3807 for (idx = 0; idx < n; ++idx)
3808 TREE_VEC_ELT (vec2, idx) = TREE_VEC_ELT (vec, idx);
3809 qsort (&TREE_VEC_ELT (vec2, 0), n, sizeof (tree), compare_case_labels);
3811 for (idx = 0; idx < n; ++idx)
3814 tree cl = TREE_VEC_ELT (vec2, idx);
3816 min = CASE_LOW (cl);
3817 max = CASE_HIGH (cl);
3819 /* If there are multiple case labels with the same destination
3820 we need to combine them to a single value range for the edge. */
3822 && CASE_LABEL (cl) == CASE_LABEL (TREE_VEC_ELT (vec2, idx + 1)))
3824 /* Skip labels until the last of the group. */
3828 && CASE_LABEL (cl) == CASE_LABEL (TREE_VEC_ELT (vec2, idx)));
3831 /* Pick up the maximum of the case label range. */
3832 if (CASE_HIGH (TREE_VEC_ELT (vec2, idx)))
3833 max = CASE_HIGH (TREE_VEC_ELT (vec2, idx));
3835 max = CASE_LOW (TREE_VEC_ELT (vec2, idx));
3838 /* Nothing to do if the range includes the default label until we
3839 can register anti-ranges. */
3840 if (min == NULL_TREE)
3843 /* Find the edge to register the assert expr on. */
3844 e = find_edge (bb, label_to_block (CASE_LABEL (cl)));
3846 /* Remove the SWITCH_EXPR operand from the FOUND_IN_SUBGRAPH bitmap.
3847 Otherwise, when we finish traversing each of the sub-graphs, we
3848 won't know whether the variables were found in the sub-graphs or
3849 if they had been found in a block upstream from BB. */
3850 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3852 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3853 to determine if any of the operands in the conditional
3854 predicate are used. */
3856 need_assert |= find_assert_locations (e->dest);
3858 /* Register the necessary assertions for the operand in the
3860 cond = build2 (max ? GE_EXPR : EQ_EXPR, boolean_type_node,
3861 op, fold_convert (TREE_TYPE (op), min));
3862 need_assert |= register_edge_assert_for (op, e, bsi, cond);
3865 cond = build2 (LE_EXPR, boolean_type_node,
3866 op, fold_convert (TREE_TYPE (op), max));
3867 need_assert |= register_edge_assert_for (op, e, bsi, cond);
3871 /* Finally, indicate that we have found the operand in the
3873 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3879 /* Traverse all the statements in block BB looking for statements that
3880 may generate useful assertions for the SSA names in their operand.
3881 If a statement produces a useful assertion A for name N_i, then the
3882 list of assertions already generated for N_i is scanned to
3883 determine if A is actually needed.
3885 If N_i already had the assertion A at a location dominating the
3886 current location, then nothing needs to be done. Otherwise, the
3887 new location for A is recorded instead.
3889 1- For every statement S in BB, all the variables used by S are
3890 added to bitmap FOUND_IN_SUBGRAPH.
3892 2- If statement S uses an operand N in a way that exposes a known
3893 value range for N, then if N was not already generated by an
3894 ASSERT_EXPR, create a new assert location for N. For instance,
3895 if N is a pointer and the statement dereferences it, we can
3896 assume that N is not NULL.
3898 3- COND_EXPRs are a special case of #2. We can derive range
3899 information from the predicate but need to insert different
3900 ASSERT_EXPRs for each of the sub-graphs rooted at the
3901 conditional block. If the last statement of BB is a conditional
3902 expression of the form 'X op Y', then
3904 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
3906 b) If the conditional is the only entry point to the sub-graph
3907 corresponding to the THEN_CLAUSE, recurse into it. On
3908 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
3909 an ASSERT_EXPR is added for the corresponding variable.
3911 c) Repeat step (b) on the ELSE_CLAUSE.
3913 d) Mark X and Y in FOUND_IN_SUBGRAPH.
3922 In this case, an assertion on the THEN clause is useful to
3923 determine that 'a' is always 9 on that edge. However, an assertion
3924 on the ELSE clause would be unnecessary.
3926 4- If BB does not end in a conditional expression, then we recurse
3927 into BB's dominator children.
3929 At the end of the recursive traversal, every SSA name will have a
3930 list of locations where ASSERT_EXPRs should be added. When a new
3931 location for name N is found, it is registered by calling
3932 register_new_assert_for. That function keeps track of all the
3933 registered assertions to prevent adding unnecessary assertions.
3934 For instance, if a pointer P_4 is dereferenced more than once in a
3935 dominator tree, only the location dominating all the dereference of
3936 P_4 will receive an ASSERT_EXPR.
3938 If this function returns true, then it means that there are names
3939 for which we need to generate ASSERT_EXPRs. Those assertions are
3940 inserted by process_assert_insertions. */
3943 find_assert_locations (basic_block bb)
3945 block_stmt_iterator si;
3950 if (TEST_BIT (blocks_visited, bb->index))
3953 SET_BIT (blocks_visited, bb->index);
3955 need_assert = false;
3957 /* Traverse all PHI nodes in BB marking used operands. */
3958 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3960 use_operand_p arg_p;
3963 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
3965 tree arg = USE_FROM_PTR (arg_p);
3966 if (TREE_CODE (arg) == SSA_NAME)
3968 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
3969 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
3974 /* Traverse all the statements in BB marking used names and looking
3975 for statements that may infer assertions for their used operands. */
3977 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3982 stmt = bsi_stmt (si);
3984 /* See if we can derive an assertion for any of STMT's operands. */
3985 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
3988 enum tree_code comp_code;
3990 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
3991 the sub-graph of a conditional block, when we return from
3992 this recursive walk, our parent will use the
3993 FOUND_IN_SUBGRAPH bitset to determine if one of the
3994 operands it was looking for was present in the sub-graph. */
3995 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3997 /* If OP is used in such a way that we can infer a value
3998 range for it, and we don't find a previous assertion for
3999 it, create a new assertion location node for OP. */
4000 if (infer_value_range (stmt, op, &comp_code, &value))
4002 /* If we are able to infer a nonzero value range for OP,
4003 then walk backwards through the use-def chain to see if OP
4004 was set via a typecast.
4006 If so, then we can also infer a nonzero value range
4007 for the operand of the NOP_EXPR. */
4008 if (comp_code == NE_EXPR && integer_zerop (value))
4011 tree def_stmt = SSA_NAME_DEF_STMT (t);
4013 while (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
4015 (GIMPLE_STMT_OPERAND (def_stmt, 1)) == NOP_EXPR
4017 (TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1),
4020 (TREE_TYPE (TREE_OPERAND
4021 (GIMPLE_STMT_OPERAND (def_stmt,
4024 t = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
4025 def_stmt = SSA_NAME_DEF_STMT (t);
4027 /* Note we want to register the assert for the
4028 operand of the NOP_EXPR after SI, not after the
4030 if (! has_single_use (t))
4032 register_new_assert_for (t, comp_code, value,
4039 /* If OP is used only once, namely in this STMT, don't
4040 bother creating an ASSERT_EXPR for it. Such an
4041 ASSERT_EXPR would do nothing but increase compile time. */
4042 if (!has_single_use (op))
4044 register_new_assert_for (op, comp_code, value, bb, NULL, si);
4050 /* Remember the last statement of the block. */
4054 /* If BB's last statement is a conditional expression
4055 involving integer operands, recurse into each of the sub-graphs
4056 rooted at BB to determine if we need to add ASSERT_EXPRs. */
4058 && TREE_CODE (last) == COND_EXPR
4059 && !fp_predicate (COND_EXPR_COND (last))
4060 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
4061 need_assert |= find_conditional_asserts (bb, last);
4064 && TREE_CODE (last) == SWITCH_EXPR
4065 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
4066 need_assert |= find_switch_asserts (bb, last);
4068 /* Recurse into the dominator children of BB. */
4069 for (son = first_dom_son (CDI_DOMINATORS, bb);
4071 son = next_dom_son (CDI_DOMINATORS, son))
4072 need_assert |= find_assert_locations (son);
4078 /* Create an ASSERT_EXPR for NAME and insert it in the location
4079 indicated by LOC. Return true if we made any edge insertions. */
4082 process_assert_insertions_for (tree name, assert_locus_t loc)
4084 /* Build the comparison expression NAME_i COMP_CODE VAL. */
4085 tree stmt, cond, assert_expr;
4089 cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
4090 assert_expr = build_assert_expr_for (cond, name);
4094 /* We have been asked to insert the assertion on an edge. This
4095 is used only by COND_EXPR and SWITCH_EXPR assertions. */
4096 #if defined ENABLE_CHECKING
4097 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
4098 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
4101 bsi_insert_on_edge (loc->e, assert_expr);
4105 /* Otherwise, we can insert right after LOC->SI iff the
4106 statement must not be the last statement in the block. */
4107 stmt = bsi_stmt (loc->si);
4108 if (!stmt_ends_bb_p (stmt))
4110 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
4114 /* If STMT must be the last statement in BB, we can only insert new
4115 assertions on the non-abnormal edge out of BB. Note that since
4116 STMT is not control flow, there may only be one non-abnormal edge
4118 FOR_EACH_EDGE (e, ei, loc->bb->succs)
4119 if (!(e->flags & EDGE_ABNORMAL))
4121 bsi_insert_on_edge (e, assert_expr);
4129 /* Process all the insertions registered for every name N_i registered
4130 in NEED_ASSERT_FOR. The list of assertions to be inserted are
4131 found in ASSERTS_FOR[i]. */
4134 process_assert_insertions (void)
4138 bool update_edges_p = false;
4139 int num_asserts = 0;
4141 if (dump_file && (dump_flags & TDF_DETAILS))
4142 dump_all_asserts (dump_file);
4144 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
4146 assert_locus_t loc = asserts_for[i];
4151 assert_locus_t next = loc->next;
4152 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
4160 bsi_commit_edge_inserts ();
4162 if (dump_file && (dump_flags & TDF_STATS))
4163 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
4168 /* Traverse the flowgraph looking for conditional jumps to insert range
4169 expressions. These range expressions are meant to provide information
4170 to optimizations that need to reason in terms of value ranges. They
4171 will not be expanded into RTL. For instance, given:
4180 this pass will transform the code into:
4186 x = ASSERT_EXPR <x, x < y>
4191 y = ASSERT_EXPR <y, x <= y>
4195 The idea is that once copy and constant propagation have run, other
4196 optimizations will be able to determine what ranges of values can 'x'
4197 take in different paths of the code, simply by checking the reaching
4198 definition of 'x'. */
4201 insert_range_assertions (void)
4207 found_in_subgraph = sbitmap_alloc (num_ssa_names);
4208 sbitmap_zero (found_in_subgraph);
4210 blocks_visited = sbitmap_alloc (last_basic_block);
4211 sbitmap_zero (blocks_visited);
4213 need_assert_for = BITMAP_ALLOC (NULL);
4214 asserts_for = XCNEWVEC (assert_locus_t, num_ssa_names);
4216 calculate_dominance_info (CDI_DOMINATORS);
4218 update_ssa_p = false;
4219 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
4220 if (find_assert_locations (e->dest))
4221 update_ssa_p = true;
4225 process_assert_insertions ();
4226 update_ssa (TODO_update_ssa_no_phi);
4229 if (dump_file && (dump_flags & TDF_DETAILS))
4231 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
4232 dump_function_to_file (current_function_decl, dump_file, dump_flags);
4235 sbitmap_free (found_in_subgraph);
4237 BITMAP_FREE (need_assert_for);
4240 /* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays
4241 and "struct" hacks. If VRP can determine that the
4242 array subscript is a constant, check if it is outside valid
4243 range. If the array subscript is a RANGE, warn if it is
4244 non-overlapping with valid range.
4245 IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */
4248 check_array_ref (tree ref, location_t* locus, bool ignore_off_by_one)
4250 value_range_t* vr = NULL;
4251 tree low_sub, up_sub;
4252 tree low_bound, up_bound = array_ref_up_bound (ref);
4254 low_sub = up_sub = TREE_OPERAND (ref, 1);
4256 if (!up_bound || !locus || TREE_NO_WARNING (ref)
4257 || TREE_CODE (up_bound) != INTEGER_CST
4258 /* Can not check flexible arrays. */
4259 || (TYPE_SIZE (TREE_TYPE (ref)) == NULL_TREE
4260 && TYPE_DOMAIN (TREE_TYPE (ref)) != NULL_TREE
4261 && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (ref))) == NULL_TREE)
4262 /* Accesses after the end of arrays of size 0 (gcc
4263 extension) and 1 are likely intentional ("struct
4265 || compare_tree_int (up_bound, 1) <= 0)
4268 low_bound = array_ref_low_bound (ref);
4270 if (TREE_CODE (low_sub) == SSA_NAME)
4272 vr = get_value_range (low_sub);
4273 if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
4275 low_sub = vr->type == VR_RANGE ? vr->max : vr->min;
4276 up_sub = vr->type == VR_RANGE ? vr->min : vr->max;
4280 if (vr && vr->type == VR_ANTI_RANGE)
4282 if (TREE_CODE (up_sub) == INTEGER_CST
4283 && tree_int_cst_lt (up_bound, up_sub)
4284 && TREE_CODE (low_sub) == INTEGER_CST
4285 && tree_int_cst_lt (low_sub, low_bound))
4287 warning (OPT_Warray_bounds,
4288 "%Harray subscript is outside array bounds", locus);
4289 TREE_NO_WARNING (ref) = 1;
4292 else if (TREE_CODE (up_sub) == INTEGER_CST
4293 && tree_int_cst_lt (up_bound, up_sub)
4294 && !tree_int_cst_equal (up_bound, up_sub)
4295 && (!ignore_off_by_one
4296 || !tree_int_cst_equal (int_const_binop (PLUS_EXPR,
4302 warning (OPT_Warray_bounds, "%Harray subscript is above array bounds",
4304 TREE_NO_WARNING (ref) = 1;
4306 else if (TREE_CODE (low_sub) == INTEGER_CST
4307 && tree_int_cst_lt (low_sub, low_bound))
4309 warning (OPT_Warray_bounds, "%Harray subscript is below array bounds",
4311 TREE_NO_WARNING (ref) = 1;
4315 /* Searches if the expr T, located at LOCATION computes
4316 address of an ARRAY_REF, and call check_array_ref on it. */
4319 search_for_addr_array(tree t, location_t* location)
4321 while (TREE_CODE (t) == SSA_NAME)
4323 t = SSA_NAME_DEF_STMT (t);
4324 if (TREE_CODE (t) != GIMPLE_MODIFY_STMT)
4326 t = GIMPLE_STMT_OPERAND (t, 1);
4330 /* We are only interested in addresses of ARRAY_REF's. */
4331 if (TREE_CODE (t) != ADDR_EXPR)
4334 /* Check each ARRAY_REFs in the reference chain. */
4337 if (TREE_CODE (t) == ARRAY_REF)
4338 check_array_ref (t, location, true /*ignore_off_by_one*/);
4340 t = TREE_OPERAND(t,0);
4342 while (handled_component_p (t));
4345 /* walk_tree() callback that checks if *TP is
4346 an ARRAY_REF inside an ADDR_EXPR (in which an array
4347 subscript one outside the valid range is allowed). Call
4348 check_array_ref for each ARRAY_REF found. The location is
4352 check_array_bounds (tree *tp, int *walk_subtree, void *data)
4355 tree stmt = (tree)data;
4356 location_t *location = EXPR_LOCUS (stmt);
4358 *walk_subtree = TRUE;
4360 if (TREE_CODE (t) == ARRAY_REF)
4361 check_array_ref (t, location, false /*ignore_off_by_one*/);
4363 if (TREE_CODE (t) == INDIRECT_REF
4364 || (TREE_CODE (t) == RETURN_EXPR && TREE_OPERAND (t, 0)))
4365 search_for_addr_array (TREE_OPERAND (t, 0), location);
4366 else if (TREE_CODE (t) == CALL_EXPR)
4369 call_expr_arg_iterator iter;
4371 FOR_EACH_CALL_EXPR_ARG (arg, iter, t)
4372 search_for_addr_array (arg, location);
4375 if (TREE_CODE (t) == ADDR_EXPR)
4376 *walk_subtree = FALSE;
4381 /* Walk over all statements of all reachable BBs and call check_array_bounds
4385 check_all_array_refs (void)
4388 block_stmt_iterator si;
4392 /* Skip bb's that are clearly unreachable. */
4393 if (single_pred_p (bb))
4395 basic_block pred_bb = EDGE_PRED (bb, 0)->src;
4396 tree ls = NULL_TREE;
4398 if (!bsi_end_p (bsi_last (pred_bb)))
4399 ls = bsi_stmt (bsi_last (pred_bb));
4401 if (ls && TREE_CODE (ls) == COND_EXPR
4402 && ((COND_EXPR_COND (ls) == boolean_false_node
4403 && (EDGE_PRED (bb, 0)->flags & EDGE_TRUE_VALUE))
4404 || (COND_EXPR_COND (ls) == boolean_true_node
4405 && (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE))))
4408 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
4409 walk_tree (bsi_stmt_ptr (si), check_array_bounds,
4410 bsi_stmt (si), NULL);
4414 /* Convert range assertion expressions into the implied copies and
4415 copy propagate away the copies. Doing the trivial copy propagation
4416 here avoids the need to run the full copy propagation pass after
4419 FIXME, this will eventually lead to copy propagation removing the
4420 names that had useful range information attached to them. For
4421 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
4422 then N_i will have the range [3, +INF].
4424 However, by converting the assertion into the implied copy
4425 operation N_i = N_j, we will then copy-propagate N_j into the uses
4426 of N_i and lose the range information. We may want to hold on to
4427 ASSERT_EXPRs a little while longer as the ranges could be used in
4428 things like jump threading.
4430 The problem with keeping ASSERT_EXPRs around is that passes after
4431 VRP need to handle them appropriately.
4433 Another approach would be to make the range information a first
4434 class property of the SSA_NAME so that it can be queried from
4435 any pass. This is made somewhat more complex by the need for
4436 multiple ranges to be associated with one SSA_NAME. */
4439 remove_range_assertions (void)
4442 block_stmt_iterator si;
4444 /* Note that the BSI iterator bump happens at the bottom of the
4445 loop and no bump is necessary if we're removing the statement
4446 referenced by the current BSI. */
4448 for (si = bsi_start (bb); !bsi_end_p (si);)
4450 tree stmt = bsi_stmt (si);
4453 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
4454 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ASSERT_EXPR)
4456 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1), var;
4457 tree cond = fold (ASSERT_EXPR_COND (rhs));
4458 use_operand_p use_p;
4459 imm_use_iterator iter;
4461 gcc_assert (cond != boolean_false_node);
4463 /* Propagate the RHS into every use of the LHS. */
4464 var = ASSERT_EXPR_VAR (rhs);
4465 FOR_EACH_IMM_USE_STMT (use_stmt, iter,
4466 GIMPLE_STMT_OPERAND (stmt, 0))
4467 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
4469 SET_USE (use_p, var);
4470 gcc_assert (TREE_CODE (var) == SSA_NAME);
4473 /* And finally, remove the copy, it is not needed. */
4474 bsi_remove (&si, true);
4475 release_defs (stmt);
4481 sbitmap_free (blocks_visited);
4485 /* Return true if STMT is interesting for VRP. */
4488 stmt_interesting_for_vrp (tree stmt)
4490 if (TREE_CODE (stmt) == PHI_NODE
4491 && is_gimple_reg (PHI_RESULT (stmt))
4492 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
4493 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
4495 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4497 tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
4498 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4500 /* In general, assignments with virtual operands are not useful
4501 for deriving ranges, with the obvious exception of calls to
4502 builtin functions. */
4503 if (TREE_CODE (lhs) == SSA_NAME
4504 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
4505 || POINTER_TYPE_P (TREE_TYPE (lhs)))
4506 && ((TREE_CODE (rhs) == CALL_EXPR
4507 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
4508 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs), 0))
4509 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
4510 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)))
4513 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
4520 /* Initialize local data structures for VRP. */
4523 vrp_initialize (void)
4527 vr_value = XCNEWVEC (value_range_t *, num_ssa_names);
4528 vr_phi_edge_counts = XCNEWVEC (int, num_ssa_names);
4532 block_stmt_iterator si;
4535 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4537 if (!stmt_interesting_for_vrp (phi))
4539 tree lhs = PHI_RESULT (phi);
4540 set_value_range_to_varying (get_value_range (lhs));
4541 DONT_SIMULATE_AGAIN (phi) = true;
4544 DONT_SIMULATE_AGAIN (phi) = false;
4547 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
4549 tree stmt = bsi_stmt (si);
4551 if (!stmt_interesting_for_vrp (stmt))
4555 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
4556 set_value_range_to_varying (get_value_range (def));
4557 DONT_SIMULATE_AGAIN (stmt) = true;
4561 DONT_SIMULATE_AGAIN (stmt) = false;
4568 /* Visit assignment STMT. If it produces an interesting range, record
4569 the SSA name in *OUTPUT_P. */
4571 static enum ssa_prop_result
4572 vrp_visit_assignment (tree stmt, tree *output_p)
4577 lhs = GIMPLE_STMT_OPERAND (stmt, 0);
4578 rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4580 /* We only keep track of ranges in integral and pointer types. */
4581 if (TREE_CODE (lhs) == SSA_NAME
4582 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
4583 /* It is valid to have NULL MIN/MAX values on a type. See
4584 build_range_type. */
4585 && TYPE_MIN_VALUE (TREE_TYPE (lhs))
4586 && TYPE_MAX_VALUE (TREE_TYPE (lhs)))
4587 || POINTER_TYPE_P (TREE_TYPE (lhs))))
4590 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
4592 extract_range_from_expr (&new_vr, rhs);
4594 /* If STMT is inside a loop, we may be able to know something
4595 else about the range of LHS by examining scalar evolution
4597 if (current_loops && (l = loop_containing_stmt (stmt)))
4598 adjust_range_with_scev (&new_vr, l, stmt, lhs);
4600 if (update_value_range (lhs, &new_vr))
4604 if (dump_file && (dump_flags & TDF_DETAILS))
4606 fprintf (dump_file, "Found new range for ");
4607 print_generic_expr (dump_file, lhs, 0);
4608 fprintf (dump_file, ": ");
4609 dump_value_range (dump_file, &new_vr);
4610 fprintf (dump_file, "\n\n");
4613 if (new_vr.type == VR_VARYING)
4614 return SSA_PROP_VARYING;
4616 return SSA_PROP_INTERESTING;
4619 return SSA_PROP_NOT_INTERESTING;
4622 /* Every other statement produces no useful ranges. */
4623 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
4624 set_value_range_to_varying (get_value_range (def));
4626 return SSA_PROP_VARYING;
4629 /* Helper that gets the value range of the SSA_NAME with version I
4630 or a symbolic range containing the SSA_NAME only if the value range
4631 is varying or undefined. */
4633 static inline value_range_t
4634 get_vr_for_comparison (int i)
4636 value_range_t vr = *(vr_value[i]);
4638 /* If name N_i does not have a valid range, use N_i as its own
4639 range. This allows us to compare against names that may
4640 have N_i in their ranges. */
4641 if (vr.type == VR_VARYING || vr.type == VR_UNDEFINED)
4644 vr.min = ssa_name (i);
4645 vr.max = ssa_name (i);
4651 /* Compare all the value ranges for names equivalent to VAR with VAL
4652 using comparison code COMP. Return the same value returned by
4653 compare_range_with_value, including the setting of
4654 *STRICT_OVERFLOW_P. */
4657 compare_name_with_value (enum tree_code comp, tree var, tree val,
4658 bool *strict_overflow_p)
4664 int used_strict_overflow;
4666 value_range_t equiv_vr;
4668 /* Get the set of equivalences for VAR. */
4669 e = get_value_range (var)->equiv;
4671 /* Start at -1. Set it to 0 if we do a comparison without relying
4672 on overflow, or 1 if all comparisons rely on overflow. */
4673 used_strict_overflow = -1;
4675 /* Compare vars' value range with val. */
4676 equiv_vr = get_vr_for_comparison (SSA_NAME_VERSION (var));
4678 retval = compare_range_with_value (comp, &equiv_vr, val, &sop);
4680 used_strict_overflow = 1;
4682 /* If the equiv set is empty we have done all work we need to do. */
4686 && used_strict_overflow > 0)
4687 *strict_overflow_p = true;
4691 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
4693 equiv_vr = get_vr_for_comparison (i);
4695 t = compare_range_with_value (comp, &equiv_vr, val, &sop);
4698 /* If we get different answers from different members
4699 of the equivalence set this check must be in a dead
4700 code region. Folding it to a trap representation
4701 would be correct here. For now just return don't-know. */
4711 used_strict_overflow = 0;
4712 else if (used_strict_overflow < 0)
4713 used_strict_overflow = 1;
4718 && used_strict_overflow > 0)
4719 *strict_overflow_p = true;
4725 /* Given a comparison code COMP and names N1 and N2, compare all the
4726 ranges equivalent to N1 against all the ranges equivalent to N2
4727 to determine the value of N1 COMP N2. Return the same value
4728 returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate
4729 whether we relied on an overflow infinity in the comparison. */
4733 compare_names (enum tree_code comp, tree n1, tree n2,
4734 bool *strict_overflow_p)
4738 bitmap_iterator bi1, bi2;
4740 int used_strict_overflow;
4741 static bitmap_obstack *s_obstack = NULL;
4742 static bitmap s_e1 = NULL, s_e2 = NULL;
4744 /* Compare the ranges of every name equivalent to N1 against the
4745 ranges of every name equivalent to N2. */
4746 e1 = get_value_range (n1)->equiv;
4747 e2 = get_value_range (n2)->equiv;
4749 /* Use the fake bitmaps if e1 or e2 are not available. */
4750 if (s_obstack == NULL)
4752 s_obstack = XNEW (bitmap_obstack);
4753 bitmap_obstack_initialize (s_obstack);
4754 s_e1 = BITMAP_ALLOC (s_obstack);
4755 s_e2 = BITMAP_ALLOC (s_obstack);
4762 /* Add N1 and N2 to their own set of equivalences to avoid
4763 duplicating the body of the loop just to check N1 and N2
4765 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
4766 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
4768 /* If the equivalence sets have a common intersection, then the two
4769 names can be compared without checking their ranges. */
4770 if (bitmap_intersect_p (e1, e2))
4772 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4773 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4775 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
4777 : boolean_false_node;
4780 /* Start at -1. Set it to 0 if we do a comparison without relying
4781 on overflow, or 1 if all comparisons rely on overflow. */
4782 used_strict_overflow = -1;
4784 /* Otherwise, compare all the equivalent ranges. First, add N1 and
4785 N2 to their own set of equivalences to avoid duplicating the body
4786 of the loop just to check N1 and N2 ranges. */
4787 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
4789 value_range_t vr1 = get_vr_for_comparison (i1);
4791 t = retval = NULL_TREE;
4792 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
4796 value_range_t vr2 = get_vr_for_comparison (i2);
4798 t = compare_ranges (comp, &vr1, &vr2, &sop);
4801 /* If we get different answers from different members
4802 of the equivalence set this check must be in a dead
4803 code region. Folding it to a trap representation
4804 would be correct here. For now just return don't-know. */
4808 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4809 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4815 used_strict_overflow = 0;
4816 else if (used_strict_overflow < 0)
4817 used_strict_overflow = 1;
4823 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4824 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4825 if (used_strict_overflow > 0)
4826 *strict_overflow_p = true;
4831 /* None of the equivalent ranges are useful in computing this
4833 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4834 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4839 /* Given a conditional predicate COND, try to determine if COND yields
4840 true or false based on the value ranges of its operands. Return
4841 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
4842 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
4843 NULL if the conditional cannot be evaluated at compile time.
4845 If USE_EQUIV_P is true, the ranges of all the names equivalent with
4846 the operands in COND are used when trying to compute its value.
4847 This is only used during final substitution. During propagation,
4848 we only check the range of each variable and not its equivalents.
4850 Set *STRICT_OVERFLOW_P to indicate whether we relied on an overflow
4851 infinity to produce the result. */
4854 vrp_evaluate_conditional_warnv (tree cond, bool use_equiv_p,
4855 bool *strict_overflow_p)
4857 gcc_assert (TREE_CODE (cond) == SSA_NAME
4858 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
4860 if (TREE_CODE (cond) == SSA_NAME)
4866 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node,
4870 value_range_t *vr = get_value_range (cond);
4871 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node,
4875 /* If COND has a known boolean range, return it. */
4879 /* Otherwise, if COND has a symbolic range of exactly one value,
4881 vr = get_value_range (cond);
4882 if (vr->type == VR_RANGE && vr->min == vr->max)
4887 tree op0 = TREE_OPERAND (cond, 0);
4888 tree op1 = TREE_OPERAND (cond, 1);
4890 /* We only deal with integral and pointer types. */
4891 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
4892 && !POINTER_TYPE_P (TREE_TYPE (op0)))
4897 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
4898 return compare_names (TREE_CODE (cond), op0, op1,
4900 else if (TREE_CODE (op0) == SSA_NAME)
4901 return compare_name_with_value (TREE_CODE (cond), op0, op1,
4903 else if (TREE_CODE (op1) == SSA_NAME)
4904 return (compare_name_with_value
4905 (swap_tree_comparison (TREE_CODE (cond)), op1, op0,
4906 strict_overflow_p));
4910 value_range_t *vr0, *vr1;
4912 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
4913 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
4916 return compare_ranges (TREE_CODE (cond), vr0, vr1,
4918 else if (vr0 && vr1 == NULL)
4919 return compare_range_with_value (TREE_CODE (cond), vr0, op1,
4921 else if (vr0 == NULL && vr1)
4922 return (compare_range_with_value
4923 (swap_tree_comparison (TREE_CODE (cond)), vr1, op0,
4924 strict_overflow_p));
4928 /* Anything else cannot be computed statically. */
4932 /* Given COND within STMT, try to simplify it based on value range
4933 information. Return NULL if the conditional can not be evaluated.
4934 The ranges of all the names equivalent with the operands in COND
4935 will be used when trying to compute the value. If the result is
4936 based on undefined signed overflow, issue a warning if
4940 vrp_evaluate_conditional (tree cond, tree stmt)
4946 ret = vrp_evaluate_conditional_warnv (cond, true, &sop);
4950 enum warn_strict_overflow_code wc;
4951 const char* warnmsg;
4953 if (is_gimple_min_invariant (ret))
4955 wc = WARN_STRICT_OVERFLOW_CONDITIONAL;
4956 warnmsg = G_("assuming signed overflow does not occur when "
4957 "simplifying conditional to constant");
4961 wc = WARN_STRICT_OVERFLOW_COMPARISON;
4962 warnmsg = G_("assuming signed overflow does not occur when "
4963 "simplifying conditional");
4966 if (issue_strict_overflow_warning (wc))
4970 if (!EXPR_HAS_LOCATION (stmt))
4971 locus = input_location;
4973 locus = EXPR_LOCATION (stmt);
4974 warning (OPT_Wstrict_overflow, "%H%s", &locus, warnmsg);
4982 /* Visit conditional statement STMT. If we can determine which edge
4983 will be taken out of STMT's basic block, record it in
4984 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
4985 SSA_PROP_VARYING. */
4987 static enum ssa_prop_result
4988 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
4993 *taken_edge_p = NULL;
4995 /* FIXME. Handle SWITCH_EXPRs. */
4996 if (TREE_CODE (stmt) == SWITCH_EXPR)
4997 return SSA_PROP_VARYING;
4999 cond = COND_EXPR_COND (stmt);
5001 if (dump_file && (dump_flags & TDF_DETAILS))
5006 fprintf (dump_file, "\nVisiting conditional with predicate: ");
5007 print_generic_expr (dump_file, cond, 0);
5008 fprintf (dump_file, "\nWith known ranges\n");
5010 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
5012 fprintf (dump_file, "\t");
5013 print_generic_expr (dump_file, use, 0);
5014 fprintf (dump_file, ": ");
5015 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
5018 fprintf (dump_file, "\n");
5021 /* Compute the value of the predicate COND by checking the known
5022 ranges of each of its operands.
5024 Note that we cannot evaluate all the equivalent ranges here
5025 because those ranges may not yet be final and with the current
5026 propagation strategy, we cannot determine when the value ranges
5027 of the names in the equivalence set have changed.
5029 For instance, given the following code fragment
5033 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
5037 Assume that on the first visit to i_14, i_5 has the temporary
5038 range [8, 8] because the second argument to the PHI function is
5039 not yet executable. We derive the range ~[0, 0] for i_14 and the
5040 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
5041 the first time, since i_14 is equivalent to the range [8, 8], we
5042 determine that the predicate is always false.
5044 On the next round of propagation, i_13 is determined to be
5045 VARYING, which causes i_5 to drop down to VARYING. So, another
5046 visit to i_14 is scheduled. In this second visit, we compute the
5047 exact same range and equivalence set for i_14, namely ~[0, 0] and
5048 { i_5 }. But we did not have the previous range for i_5
5049 registered, so vrp_visit_assignment thinks that the range for
5050 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
5051 is not visited again, which stops propagation from visiting
5052 statements in the THEN clause of that if().
5054 To properly fix this we would need to keep the previous range
5055 value for the names in the equivalence set. This way we would've
5056 discovered that from one visit to the other i_5 changed from
5057 range [8, 8] to VR_VARYING.
5059 However, fixing this apparent limitation may not be worth the
5060 additional checking. Testing on several code bases (GCC, DLV,
5061 MICO, TRAMP3D and SPEC2000) showed that doing this results in
5062 4 more predicates folded in SPEC. */
5064 val = vrp_evaluate_conditional_warnv (cond, false, &sop);
5068 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
5071 if (dump_file && (dump_flags & TDF_DETAILS))
5073 "\nIgnoring predicate evaluation because "
5074 "it assumes that signed overflow is undefined");
5079 if (dump_file && (dump_flags & TDF_DETAILS))
5081 fprintf (dump_file, "\nPredicate evaluates to: ");
5082 if (val == NULL_TREE)
5083 fprintf (dump_file, "DON'T KNOW\n");
5085 print_generic_stmt (dump_file, val, 0);
5088 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
5092 /* Evaluate statement STMT. If the statement produces a useful range,
5093 return SSA_PROP_INTERESTING and record the SSA name with the
5094 interesting range into *OUTPUT_P.
5096 If STMT is a conditional branch and we can determine its truth
5097 value, the taken edge is recorded in *TAKEN_EDGE_P.
5099 If STMT produces a varying value, return SSA_PROP_VARYING. */
5101 static enum ssa_prop_result
5102 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
5108 if (dump_file && (dump_flags & TDF_DETAILS))
5110 fprintf (dump_file, "\nVisiting statement:\n");
5111 print_generic_stmt (dump_file, stmt, dump_flags);
5112 fprintf (dump_file, "\n");
5115 ann = stmt_ann (stmt);
5116 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
5118 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
5120 /* In general, assignments with virtual operands are not useful
5121 for deriving ranges, with the obvious exception of calls to
5122 builtin functions. */
5123 if ((TREE_CODE (rhs) == CALL_EXPR
5124 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
5125 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs), 0))
5126 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
5127 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
5128 return vrp_visit_assignment (stmt, output_p);
5130 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
5131 return vrp_visit_cond_stmt (stmt, taken_edge_p);
5133 /* All other statements produce nothing of interest for VRP, so mark
5134 their outputs varying and prevent further simulation. */
5135 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
5136 set_value_range_to_varying (get_value_range (def));
5138 return SSA_PROP_VARYING;
5142 /* Meet operation for value ranges. Given two value ranges VR0 and
5143 VR1, store in VR0 a range that contains both VR0 and VR1. This
5144 may not be the smallest possible such range. */
5147 vrp_meet (value_range_t *vr0, value_range_t *vr1)
5149 if (vr0->type == VR_UNDEFINED)
5151 copy_value_range (vr0, vr1);
5155 if (vr1->type == VR_UNDEFINED)
5157 /* Nothing to do. VR0 already has the resulting range. */
5161 if (vr0->type == VR_VARYING)
5163 /* Nothing to do. VR0 already has the resulting range. */
5167 if (vr1->type == VR_VARYING)
5169 set_value_range_to_varying (vr0);
5173 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
5178 /* Compute the convex hull of the ranges. The lower limit of
5179 the new range is the minimum of the two ranges. If they
5180 cannot be compared, then give up. */
5181 cmp = compare_values (vr0->min, vr1->min);
5182 if (cmp == 0 || cmp == 1)
5189 /* Similarly, the upper limit of the new range is the maximum
5190 of the two ranges. If they cannot be compared, then
5192 cmp = compare_values (vr0->max, vr1->max);
5193 if (cmp == 0 || cmp == -1)
5200 /* Check for useless ranges. */
5201 if (INTEGRAL_TYPE_P (TREE_TYPE (min))
5202 && ((vrp_val_is_min (min) || is_overflow_infinity (min))
5203 && (vrp_val_is_max (max) || is_overflow_infinity (max))))
5206 /* The resulting set of equivalences is the intersection of
5208 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
5209 bitmap_and_into (vr0->equiv, vr1->equiv);
5210 else if (vr0->equiv && !vr1->equiv)
5211 bitmap_clear (vr0->equiv);
5213 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
5215 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
5217 /* Two anti-ranges meet only if their complements intersect.
5218 Only handle the case of identical ranges. */
5219 if (compare_values (vr0->min, vr1->min) == 0
5220 && compare_values (vr0->max, vr1->max) == 0
5221 && compare_values (vr0->min, vr0->max) == 0)
5223 /* The resulting set of equivalences is the intersection of
5225 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
5226 bitmap_and_into (vr0->equiv, vr1->equiv);
5227 else if (vr0->equiv && !vr1->equiv)
5228 bitmap_clear (vr0->equiv);
5233 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
5235 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
5236 only handle the case where the ranges have an empty intersection.
5237 The result of the meet operation is the anti-range. */
5238 if (!symbolic_range_p (vr0)
5239 && !symbolic_range_p (vr1)
5240 && !value_ranges_intersect_p (vr0, vr1))
5242 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
5243 set. We need to compute the intersection of the two
5244 equivalence sets. */
5245 if (vr1->type == VR_ANTI_RANGE)
5246 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
5248 /* The resulting set of equivalences is the intersection of
5250 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
5251 bitmap_and_into (vr0->equiv, vr1->equiv);
5252 else if (vr0->equiv && !vr1->equiv)
5253 bitmap_clear (vr0->equiv);
5264 /* Failed to find an efficient meet. Before giving up and setting
5265 the result to VARYING, see if we can at least derive a useful
5266 anti-range. FIXME, all this nonsense about distinguishing
5267 anti-ranges from ranges is necessary because of the odd
5268 semantics of range_includes_zero_p and friends. */
5269 if (!symbolic_range_p (vr0)
5270 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
5271 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
5272 && !symbolic_range_p (vr1)
5273 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
5274 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
5276 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
5278 /* Since this meet operation did not result from the meeting of
5279 two equivalent names, VR0 cannot have any equivalences. */
5281 bitmap_clear (vr0->equiv);
5284 set_value_range_to_varying (vr0);
5288 /* Visit all arguments for PHI node PHI that flow through executable
5289 edges. If a valid value range can be derived from all the incoming
5290 value ranges, set a new range for the LHS of PHI. */
5292 static enum ssa_prop_result
5293 vrp_visit_phi_node (tree phi)
5296 tree lhs = PHI_RESULT (phi);
5297 value_range_t *lhs_vr = get_value_range (lhs);
5298 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
5299 int edges, old_edges;
5301 copy_value_range (&vr_result, lhs_vr);
5303 if (dump_file && (dump_flags & TDF_DETAILS))
5305 fprintf (dump_file, "\nVisiting PHI node: ");
5306 print_generic_expr (dump_file, phi, dump_flags);
5310 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
5312 edge e = PHI_ARG_EDGE (phi, i);
5314 if (dump_file && (dump_flags & TDF_DETAILS))
5317 "\n Argument #%d (%d -> %d %sexecutable)\n",
5318 i, e->src->index, e->dest->index,
5319 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
5322 if (e->flags & EDGE_EXECUTABLE)
5324 tree arg = PHI_ARG_DEF (phi, i);
5325 value_range_t vr_arg;
5329 if (TREE_CODE (arg) == SSA_NAME)
5331 vr_arg = *(get_value_range (arg));
5335 if (is_overflow_infinity (arg))
5337 arg = copy_node (arg);
5338 TREE_OVERFLOW (arg) = 0;
5341 vr_arg.type = VR_RANGE;
5344 vr_arg.equiv = NULL;
5347 if (dump_file && (dump_flags & TDF_DETAILS))
5349 fprintf (dump_file, "\t");
5350 print_generic_expr (dump_file, arg, dump_flags);
5351 fprintf (dump_file, "\n\tValue: ");
5352 dump_value_range (dump_file, &vr_arg);
5353 fprintf (dump_file, "\n");
5356 vrp_meet (&vr_result, &vr_arg);
5358 if (vr_result.type == VR_VARYING)
5363 if (vr_result.type == VR_VARYING)
5366 old_edges = vr_phi_edge_counts[SSA_NAME_VERSION (lhs)];
5367 vr_phi_edge_counts[SSA_NAME_VERSION (lhs)] = edges;
5369 /* To prevent infinite iterations in the algorithm, derive ranges
5370 when the new value is slightly bigger or smaller than the
5371 previous one. We don't do this if we have seen a new executable
5372 edge; this helps us avoid an overflow infinity for conditionals
5373 which are not in a loop. */
5374 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE
5375 && edges <= old_edges)
5377 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
5379 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
5380 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
5382 /* If the new minimum is smaller or larger than the previous
5383 one, go all the way to -INF. In the first case, to avoid
5384 iterating millions of times to reach -INF, and in the
5385 other case to avoid infinite bouncing between different
5387 if (cmp_min > 0 || cmp_min < 0)
5389 /* If we will end up with a (-INF, +INF) range, set it
5391 if (vrp_val_is_max (vr_result.max))
5394 if (!needs_overflow_infinity (TREE_TYPE (vr_result.min)))
5395 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
5396 else if (supports_overflow_infinity (TREE_TYPE (vr_result.min)))
5398 negative_overflow_infinity (TREE_TYPE (vr_result.min));
5403 /* Similarly, if the new maximum is smaller or larger than
5404 the previous one, go all the way to +INF. */
5405 if (cmp_max < 0 || cmp_max > 0)
5407 /* If we will end up with a (-INF, +INF) range, set it
5409 if (vrp_val_is_min (vr_result.min))
5412 if (!needs_overflow_infinity (TREE_TYPE (vr_result.max)))
5413 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
5414 else if (supports_overflow_infinity (TREE_TYPE (vr_result.max)))
5416 positive_overflow_infinity (TREE_TYPE (vr_result.max));
5423 /* If the new range is different than the previous value, keep
5425 if (update_value_range (lhs, &vr_result))
5426 return SSA_PROP_INTERESTING;
5428 /* Nothing changed, don't add outgoing edges. */
5429 return SSA_PROP_NOT_INTERESTING;
5431 /* No match found. Set the LHS to VARYING. */
5433 set_value_range_to_varying (lhs_vr);
5434 return SSA_PROP_VARYING;
5437 /* Simplify a division or modulo operator to a right shift or
5438 bitwise and if the first operand is unsigned or is greater
5439 than zero and the second operand is an exact power of two. */
5442 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
5445 tree op = TREE_OPERAND (rhs, 0);
5446 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
5448 if (TYPE_UNSIGNED (TREE_TYPE (op)))
5450 val = integer_one_node;
5456 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node, &sop);
5460 && integer_onep (val)
5461 && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
5465 if (!EXPR_HAS_LOCATION (stmt))
5466 locus = input_location;
5468 locus = EXPR_LOCATION (stmt);
5469 warning (OPT_Wstrict_overflow,
5470 ("%Hassuming signed overflow does not occur when "
5471 "simplifying / or %% to >> or &"),
5476 if (val && integer_onep (val))
5479 tree op0 = TREE_OPERAND (rhs, 0);
5480 tree op1 = TREE_OPERAND (rhs, 1);
5482 if (rhs_code == TRUNC_DIV_EXPR)
5484 t = build_int_cst (NULL_TREE, tree_log2 (op1));
5485 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
5489 t = build_int_cst (TREE_TYPE (op1), 1);
5490 t = int_const_binop (MINUS_EXPR, op1, t, 0);
5491 t = fold_convert (TREE_TYPE (op0), t);
5492 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
5495 GIMPLE_STMT_OPERAND (stmt, 1) = t;
5500 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
5501 ABS_EXPR. If the operand is <= 0, then simplify the
5502 ABS_EXPR into a NEGATE_EXPR. */
5505 simplify_abs_using_ranges (tree stmt, tree rhs)
5508 tree op = TREE_OPERAND (rhs, 0);
5509 tree type = TREE_TYPE (op);
5510 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
5512 if (TYPE_UNSIGNED (type))
5514 val = integer_zero_node;
5520 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node, &sop);
5524 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node,
5529 if (integer_zerop (val))
5530 val = integer_one_node;
5531 else if (integer_onep (val))
5532 val = integer_zero_node;
5537 && (integer_onep (val) || integer_zerop (val)))
5541 if (sop && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
5545 if (!EXPR_HAS_LOCATION (stmt))
5546 locus = input_location;
5548 locus = EXPR_LOCATION (stmt);
5549 warning (OPT_Wstrict_overflow,
5550 ("%Hassuming signed overflow does not occur when "
5551 "simplifying abs (X) to X or -X"),
5555 if (integer_onep (val))
5556 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
5560 GIMPLE_STMT_OPERAND (stmt, 1) = t;
5566 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
5567 a known value range VR.
5569 If there is one and only one value which will satisfy the
5570 conditional, then return that value. Else return NULL. */
5573 test_for_singularity (enum tree_code cond_code, tree op0,
5574 tree op1, value_range_t *vr)
5579 /* Extract minimum/maximum values which satisfy the
5580 the conditional as it was written. */
5581 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
5583 /* This should not be negative infinity; there is no overflow
5585 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
5588 if (cond_code == LT_EXPR && !is_overflow_infinity (max))
5590 tree one = build_int_cst (TREE_TYPE (op0), 1);
5591 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
5594 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
5596 /* This should not be positive infinity; there is no overflow
5598 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
5601 if (cond_code == GT_EXPR && !is_overflow_infinity (min))
5603 tree one = build_int_cst (TREE_TYPE (op0), 1);
5604 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
5608 /* Now refine the minimum and maximum values using any
5609 value range information we have for op0. */
5612 if (compare_values (vr->min, min) == -1)
5616 if (compare_values (vr->max, max) == 1)
5621 /* If the new min/max values have converged to a single value,
5622 then there is only one value which can satisfy the condition,
5623 return that value. */
5624 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
5630 /* Simplify a conditional using a relational operator to an equality
5631 test if the range information indicates only one value can satisfy
5632 the original conditional. */
5635 simplify_cond_using_ranges (tree stmt)
5637 tree cond = COND_EXPR_COND (stmt);
5638 tree op0 = TREE_OPERAND (cond, 0);
5639 tree op1 = TREE_OPERAND (cond, 1);
5640 enum tree_code cond_code = TREE_CODE (cond);
5642 if (cond_code != NE_EXPR
5643 && cond_code != EQ_EXPR
5644 && TREE_CODE (op0) == SSA_NAME
5645 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
5646 && is_gimple_min_invariant (op1))
5648 value_range_t *vr = get_value_range (op0);
5650 /* If we have range information for OP0, then we might be
5651 able to simplify this conditional. */
5652 if (vr->type == VR_RANGE)
5654 tree new = test_for_singularity (cond_code, op0, op1, vr);
5660 fprintf (dump_file, "Simplified relational ");
5661 print_generic_expr (dump_file, cond, 0);
5662 fprintf (dump_file, " into ");
5665 COND_EXPR_COND (stmt)
5666 = build2 (EQ_EXPR, boolean_type_node, op0, new);
5671 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
5672 fprintf (dump_file, "\n");
5678 /* Try again after inverting the condition. We only deal
5679 with integral types here, so no need to worry about
5680 issues with inverting FP comparisons. */
5681 cond_code = invert_tree_comparison (cond_code, false);
5682 new = test_for_singularity (cond_code, op0, op1, vr);
5688 fprintf (dump_file, "Simplified relational ");
5689 print_generic_expr (dump_file, cond, 0);
5690 fprintf (dump_file, " into ");
5693 COND_EXPR_COND (stmt)
5694 = build2 (NE_EXPR, boolean_type_node, op0, new);
5699 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
5700 fprintf (dump_file, "\n");
5709 /* Simplify STMT using ranges if possible. */
5712 simplify_stmt_using_ranges (tree stmt)
5714 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
5716 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
5717 enum tree_code rhs_code = TREE_CODE (rhs);
5719 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
5720 and BIT_AND_EXPR respectively if the first operand is greater
5721 than zero and the second operand is an exact power of two. */
5722 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
5723 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
5724 && integer_pow2p (TREE_OPERAND (rhs, 1)))
5725 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
5727 /* Transform ABS (X) into X or -X as appropriate. */
5728 if (rhs_code == ABS_EXPR
5729 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
5730 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
5731 simplify_abs_using_ranges (stmt, rhs);
5733 else if (TREE_CODE (stmt) == COND_EXPR
5734 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
5736 simplify_cond_using_ranges (stmt);
5740 /* Stack of dest,src equivalency pairs that need to be restored after
5741 each attempt to thread a block's incoming edge to an outgoing edge.
5743 A NULL entry is used to mark the end of pairs which need to be
5745 static VEC(tree,heap) *stack;
5747 /* A trivial wrapper so that we can present the generic jump threading
5748 code with a simple API for simplifying statements. STMT is the
5749 statement we want to simplify, WITHIN_STMT provides the location
5750 for any overflow warnings. */
5753 simplify_stmt_for_jump_threading (tree stmt, tree within_stmt)
5755 /* We only use VRP information to simplify conditionals. This is
5756 overly conservative, but it's unclear if doing more would be
5757 worth the compile time cost. */
5758 if (TREE_CODE (stmt) != COND_EXPR)
5761 return vrp_evaluate_conditional (COND_EXPR_COND (stmt), within_stmt);
5764 /* Blocks which have more than one predecessor and more than
5765 one successor present jump threading opportunities. ie,
5766 when the block is reached from a specific predecessor, we
5767 may be able to determine which of the outgoing edges will
5768 be traversed. When this optimization applies, we are able
5769 to avoid conditionals at runtime and we may expose secondary
5770 optimization opportunities.
5772 This routine is effectively a driver for the generic jump
5773 threading code. It basically just presents the generic code
5774 with edges that may be suitable for jump threading.
5776 Unlike DOM, we do not iterate VRP if jump threading was successful.
5777 While iterating may expose new opportunities for VRP, it is expected
5778 those opportunities would be very limited and the compile time cost
5779 to expose those opportunities would be significant.
5781 As jump threading opportunities are discovered, they are registered
5782 for later realization. */
5785 identify_jump_threads (void)
5790 /* Ugh. When substituting values earlier in this pass we can
5791 wipe the dominance information. So rebuild the dominator
5792 information as we need it within the jump threading code. */
5793 calculate_dominance_info (CDI_DOMINATORS);
5795 /* We do not allow VRP information to be used for jump threading
5796 across a back edge in the CFG. Otherwise it becomes too
5797 difficult to avoid eliminating loop exit tests. Of course
5798 EDGE_DFS_BACK is not accurate at this time so we have to
5800 mark_dfs_back_edges ();
5802 /* Allocate our unwinder stack to unwind any temporary equivalences
5803 that might be recorded. */
5804 stack = VEC_alloc (tree, heap, 20);
5806 /* To avoid lots of silly node creation, we create a single
5807 conditional and just modify it in-place when attempting to
5809 dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL);
5810 dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL);
5812 /* Walk through all the blocks finding those which present a
5813 potential jump threading opportunity. We could set this up
5814 as a dominator walker and record data during the walk, but
5815 I doubt it's worth the effort for the classes of jump
5816 threading opportunities we are trying to identify at this
5817 point in compilation. */
5822 /* If the generic jump threading code does not find this block
5823 interesting, then there is nothing to do. */
5824 if (! potentially_threadable_block (bb))
5827 /* We only care about blocks ending in a COND_EXPR. While there
5828 may be some value in handling SWITCH_EXPR here, I doubt it's
5829 terribly important. */
5830 last = bsi_stmt (bsi_last (bb));
5831 if (TREE_CODE (last) != COND_EXPR)
5834 /* We're basically looking for any kind of conditional with
5835 integral type arguments. */
5836 cond = COND_EXPR_COND (last);
5837 if ((TREE_CODE (cond) == SSA_NAME
5838 && INTEGRAL_TYPE_P (TREE_TYPE (cond)))
5839 || (COMPARISON_CLASS_P (cond)
5840 && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
5841 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0)))
5842 && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME
5843 || is_gimple_min_invariant (TREE_OPERAND (cond, 1)))
5844 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
5849 /* We've got a block with multiple predecessors and multiple
5850 successors which also ends in a suitable conditional. For
5851 each predecessor, see if we can thread it to a specific
5853 FOR_EACH_EDGE (e, ei, bb->preds)
5855 /* Do not thread across back edges or abnormal edges
5857 if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
5860 thread_across_edge (dummy, e, true,
5862 simplify_stmt_for_jump_threading);
5867 /* We do not actually update the CFG or SSA graphs at this point as
5868 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
5869 handle ASSERT_EXPRs gracefully. */
5872 /* We identified all the jump threading opportunities earlier, but could
5873 not transform the CFG at that time. This routine transforms the
5874 CFG and arranges for the dominator tree to be rebuilt if necessary.
5876 Note the SSA graph update will occur during the normal TODO
5877 processing by the pass manager. */
5879 finalize_jump_threads (void)
5881 thread_through_all_blocks (false);
5882 VEC_free (tree, heap, stack);
5886 /* Traverse all the blocks folding conditionals with known ranges. */
5892 prop_value_t *single_val_range;
5893 bool do_value_subst_p;
5897 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
5898 dump_all_value_ranges (dump_file);
5899 fprintf (dump_file, "\n");
5902 /* We may have ended with ranges that have exactly one value. Those
5903 values can be substituted as any other copy/const propagated
5904 value using substitute_and_fold. */
5905 single_val_range = XCNEWVEC (prop_value_t, num_ssa_names);
5907 do_value_subst_p = false;
5908 for (i = 0; i < num_ssa_names; i++)
5910 && vr_value[i]->type == VR_RANGE
5911 && vr_value[i]->min == vr_value[i]->max)
5913 single_val_range[i].value = vr_value[i]->min;
5914 do_value_subst_p = true;
5917 if (!do_value_subst_p)
5919 /* We found no single-valued ranges, don't waste time trying to
5920 do single value substitution in substitute_and_fold. */
5921 free (single_val_range);
5922 single_val_range = NULL;
5925 substitute_and_fold (single_val_range, true);
5927 if (warn_array_bounds)
5928 check_all_array_refs ();
5930 /* We must identify jump threading opportunities before we release
5931 the datastructures built by VRP. */
5932 identify_jump_threads ();
5934 /* Free allocated memory. */
5935 for (i = 0; i < num_ssa_names; i++)
5938 BITMAP_FREE (vr_value[i]->equiv);
5942 free (single_val_range);
5944 free (vr_phi_edge_counts);
5946 /* So that we can distinguish between VRP data being available
5947 and not available. */
5949 vr_phi_edge_counts = NULL;
5953 /* Main entry point to VRP (Value Range Propagation). This pass is
5954 loosely based on J. R. C. Patterson, ``Accurate Static Branch
5955 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
5956 Programming Language Design and Implementation, pp. 67-78, 1995.
5957 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
5959 This is essentially an SSA-CCP pass modified to deal with ranges
5960 instead of constants.
5962 While propagating ranges, we may find that two or more SSA name
5963 have equivalent, though distinct ranges. For instance,
5966 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
5968 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
5972 In the code above, pointer p_5 has range [q_2, q_2], but from the
5973 code we can also determine that p_5 cannot be NULL and, if q_2 had
5974 a non-varying range, p_5's range should also be compatible with it.
5976 These equivalences are created by two expressions: ASSERT_EXPR and
5977 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
5978 result of another assertion, then we can use the fact that p_5 and
5979 p_4 are equivalent when evaluating p_5's range.
5981 Together with value ranges, we also propagate these equivalences
5982 between names so that we can take advantage of information from
5983 multiple ranges when doing final replacement. Note that this
5984 equivalency relation is transitive but not symmetric.
5986 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
5987 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
5988 in contexts where that assertion does not hold (e.g., in line 6).
5990 TODO, the main difference between this pass and Patterson's is that
5991 we do not propagate edge probabilities. We only compute whether
5992 edges can be taken or not. That is, instead of having a spectrum
5993 of jump probabilities between 0 and 1, we only deal with 0, 1 and
5994 DON'T KNOW. In the future, it may be worthwhile to propagate
5995 probabilities to aid branch prediction. */
6000 loop_optimizer_init (LOOPS_NORMAL | LOOPS_HAVE_RECORDED_EXITS);
6001 rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa);
6004 insert_range_assertions ();
6007 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
6010 /* ASSERT_EXPRs must be removed before finalizing jump threads
6011 as finalizing jump threads calls the CFG cleanup code which
6012 does not properly handle ASSERT_EXPRs. */
6013 remove_range_assertions ();
6015 /* If we exposed any new variables, go ahead and put them into
6016 SSA form now, before we handle jump threading. This simplifies
6017 interactions between rewriting of _DECL nodes into SSA form
6018 and rewriting SSA_NAME nodes into SSA form after block
6019 duplication and CFG manipulation. */
6020 update_ssa (TODO_update_ssa);
6022 finalize_jump_threads ();
6024 loop_optimizer_finalize ();
6032 return flag_tree_vrp != 0;
6035 struct tree_opt_pass pass_vrp =
6038 gate_vrp, /* gate */
6039 execute_vrp, /* execute */
6042 0, /* static_pass_number */
6043 TV_TREE_VRP, /* tv_id */
6044 PROP_ssa | PROP_alias, /* properties_required */
6045 0, /* properties_provided */
6046 0, /* properties_destroyed */
6047 0, /* todo_flags_start */
6052 | TODO_update_ssa, /* todo_flags_finish */