1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
24 #include "coretypes.h"
29 #include "basic-block.h"
30 #include "tree-flow.h"
31 #include "tree-pass.h"
32 #include "tree-dump.h"
34 #include "diagnostic.h"
38 #include "tree-scalar-evolution.h"
39 #include "tree-ssa-propagate.h"
40 #include "tree-chrec.h"
42 /* Set of SSA names found during the dominator traversal of a
43 sub-graph in find_assert_locations. */
44 static sbitmap found_in_subgraph;
46 /* Local functions. */
47 static int compare_values (tree val1, tree val2);
48 static int compare_values_warnv (tree val1, tree val2, bool *);
49 static void vrp_meet (value_range_t *, value_range_t *);
50 static tree vrp_evaluate_conditional_warnv (tree, bool, bool *);
52 /* Location information for ASSERT_EXPRs. Each instance of this
53 structure describes an ASSERT_EXPR for an SSA name. Since a single
54 SSA name may have more than one assertion associated with it, these
55 locations are kept in a linked list attached to the corresponding
59 /* Basic block where the assertion would be inserted. */
62 /* Some assertions need to be inserted on an edge (e.g., assertions
63 generated by COND_EXPRs). In those cases, BB will be NULL. */
66 /* Pointer to the statement that generated this assertion. */
67 block_stmt_iterator si;
69 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
70 enum tree_code comp_code;
72 /* Value being compared against. */
75 /* Next node in the linked list. */
76 struct assert_locus_d *next;
79 typedef struct assert_locus_d *assert_locus_t;
81 /* If bit I is present, it means that SSA name N_i has a list of
82 assertions that should be inserted in the IL. */
83 static bitmap need_assert_for;
85 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
86 holds a list of ASSERT_LOCUS_T nodes that describe where
87 ASSERT_EXPRs for SSA name N_I should be inserted. */
88 static assert_locus_t *asserts_for;
90 /* Set of blocks visited in find_assert_locations. Used to avoid
91 visiting the same block more than once. */
92 static sbitmap blocks_visited;
94 /* Value range array. After propagation, VR_VALUE[I] holds the range
95 of values that SSA name N_I may take. */
96 static value_range_t **vr_value;
99 /* Return whether TYPE should use an overflow infinity distinct from
100 TYPE_{MIN,MAX}_VALUE. We use an overflow infinity value to
101 represent a signed overflow during VRP computations. An infinity
102 is distinct from a half-range, which will go from some number to
103 TYPE_{MIN,MAX}_VALUE. */
106 needs_overflow_infinity (tree type)
108 return INTEGRAL_TYPE_P (type) && !TYPE_OVERFLOW_WRAPS (type);
111 /* Return whether TYPE can support our overflow infinity
112 representation: we use the TREE_OVERFLOW flag, which only exists
113 for constants. If TYPE doesn't support this, we don't optimize
114 cases which would require signed overflow--we drop them to
118 supports_overflow_infinity (tree type)
120 #ifdef ENABLE_CHECKING
121 gcc_assert (needs_overflow_infinity (type));
123 return (TYPE_MIN_VALUE (type) != NULL_TREE
124 && CONSTANT_CLASS_P (TYPE_MIN_VALUE (type))
125 && TYPE_MAX_VALUE (type) != NULL_TREE
126 && CONSTANT_CLASS_P (TYPE_MAX_VALUE (type)));
129 /* VAL is the maximum or minimum value of a type. Return a
130 corresponding overflow infinity. */
133 make_overflow_infinity (tree val)
135 #ifdef ENABLE_CHECKING
136 gcc_assert (val != NULL_TREE && CONSTANT_CLASS_P (val));
138 val = copy_node (val);
139 TREE_OVERFLOW (val) = 1;
143 /* Return a negative overflow infinity for TYPE. */
146 negative_overflow_infinity (tree type)
148 #ifdef ENABLE_CHECKING
149 gcc_assert (supports_overflow_infinity (type));
151 return make_overflow_infinity (TYPE_MIN_VALUE (type));
154 /* Return a positive overflow infinity for TYPE. */
157 positive_overflow_infinity (tree type)
159 #ifdef ENABLE_CHECKING
160 gcc_assert (supports_overflow_infinity (type));
162 return make_overflow_infinity (TYPE_MAX_VALUE (type));
165 /* Return whether VAL is a negative overflow infinity. */
168 is_negative_overflow_infinity (tree val)
170 return (needs_overflow_infinity (TREE_TYPE (val))
171 && CONSTANT_CLASS_P (val)
172 && TREE_OVERFLOW (val)
173 && operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0));
176 /* Return whether VAL is a positive overflow infinity. */
179 is_positive_overflow_infinity (tree val)
181 return (needs_overflow_infinity (TREE_TYPE (val))
182 && CONSTANT_CLASS_P (val)
183 && TREE_OVERFLOW (val)
184 && operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0));
187 /* Return whether VAL is a positive or negative overflow infinity. */
190 is_overflow_infinity (tree val)
192 return (needs_overflow_infinity (TREE_TYPE (val))
193 && CONSTANT_CLASS_P (val)
194 && TREE_OVERFLOW (val)
195 && (operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0)
196 || operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0)));
200 /* Return true if ARG is marked with the nonnull attribute in the
201 current function signature. */
204 nonnull_arg_p (tree arg)
206 tree t, attrs, fntype;
207 unsigned HOST_WIDE_INT arg_num;
209 gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
211 /* The static chain decl is always non null. */
212 if (arg == cfun->static_chain_decl)
215 fntype = TREE_TYPE (current_function_decl);
216 attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype));
218 /* If "nonnull" wasn't specified, we know nothing about the argument. */
219 if (attrs == NULL_TREE)
222 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
223 if (TREE_VALUE (attrs) == NULL_TREE)
226 /* Get the position number for ARG in the function signature. */
227 for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl);
229 t = TREE_CHAIN (t), arg_num++)
235 gcc_assert (t == arg);
237 /* Now see if ARG_NUM is mentioned in the nonnull list. */
238 for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
240 if (compare_tree_int (TREE_VALUE (t), arg_num) == 0)
248 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
251 set_value_range (value_range_t *vr, enum value_range_type t, tree min,
252 tree max, bitmap equiv)
254 #if defined ENABLE_CHECKING
255 /* Check the validity of the range. */
256 if (t == VR_RANGE || t == VR_ANTI_RANGE)
260 gcc_assert (min && max);
262 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
263 gcc_assert ((min != TYPE_MIN_VALUE (TREE_TYPE (min))
264 && !is_negative_overflow_infinity (min))
265 || (max != TYPE_MAX_VALUE (TREE_TYPE (max))
266 && !is_positive_overflow_infinity (max)));
268 cmp = compare_values (min, max);
269 gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
272 if (t == VR_UNDEFINED || t == VR_VARYING)
273 gcc_assert (min == NULL_TREE && max == NULL_TREE);
275 if (t == VR_UNDEFINED || t == VR_VARYING)
276 gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
283 /* Since updating the equivalence set involves deep copying the
284 bitmaps, only do it if absolutely necessary. */
285 if (vr->equiv == NULL)
286 vr->equiv = BITMAP_ALLOC (NULL);
288 if (equiv != vr->equiv)
290 if (equiv && !bitmap_empty_p (equiv))
291 bitmap_copy (vr->equiv, equiv);
293 bitmap_clear (vr->equiv);
298 /* Copy value range FROM into value range TO. */
301 copy_value_range (value_range_t *to, value_range_t *from)
303 set_value_range (to, from->type, from->min, from->max, from->equiv);
307 /* Set value range VR to VR_VARYING. */
310 set_value_range_to_varying (value_range_t *vr)
312 vr->type = VR_VARYING;
313 vr->min = vr->max = NULL_TREE;
315 bitmap_clear (vr->equiv);
318 /* Set value range VR to a non-negative range of type TYPE.
319 OVERFLOW_INFINITY indicates whether to use a overflow infinity
320 rather than TYPE_MAX_VALUE; this should be true if we determine
321 that the range is nonnegative based on the assumption that signed
322 overflow does not occur. */
325 set_value_range_to_nonnegative (value_range_t *vr, tree type,
326 bool overflow_infinity)
330 if (overflow_infinity && !supports_overflow_infinity (type))
332 set_value_range_to_varying (vr);
336 zero = build_int_cst (type, 0);
337 set_value_range (vr, VR_RANGE, zero,
339 ? positive_overflow_infinity (type)
340 : TYPE_MAX_VALUE (type)),
344 /* Set value range VR to a non-NULL range of type TYPE. */
347 set_value_range_to_nonnull (value_range_t *vr, tree type)
349 tree zero = build_int_cst (type, 0);
350 set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
354 /* Set value range VR to a NULL range of type TYPE. */
357 set_value_range_to_null (value_range_t *vr, tree type)
359 tree zero = build_int_cst (type, 0);
360 set_value_range (vr, VR_RANGE, zero, zero, vr->equiv);
364 /* Set value range VR to a range of a truthvalue of type TYPE. */
367 set_value_range_to_truthvalue (value_range_t *vr, tree type)
369 if (TYPE_PRECISION (type) == 1)
370 set_value_range_to_varying (vr);
372 set_value_range (vr, VR_RANGE,
373 build_int_cst (type, 0), build_int_cst (type, 1),
378 /* Set value range VR to VR_UNDEFINED. */
381 set_value_range_to_undefined (value_range_t *vr)
383 vr->type = VR_UNDEFINED;
384 vr->min = vr->max = NULL_TREE;
386 bitmap_clear (vr->equiv);
390 /* Return value range information for VAR.
392 If we have no values ranges recorded (ie, VRP is not running), then
393 return NULL. Otherwise create an empty range if none existed for VAR. */
395 static value_range_t *
396 get_value_range (tree var)
400 unsigned ver = SSA_NAME_VERSION (var);
402 /* If we have no recorded ranges, then return NULL. */
410 /* Create a default value range. */
411 vr_value[ver] = vr = XCNEW (value_range_t);
413 /* Allocate an equivalence set. */
414 vr->equiv = BITMAP_ALLOC (NULL);
416 /* If VAR is a default definition, the variable can take any value
418 sym = SSA_NAME_VAR (var);
419 if (SSA_NAME_IS_DEFAULT_DEF (var))
421 /* Try to use the "nonnull" attribute to create ~[0, 0]
422 anti-ranges for pointers. Note that this is only valid with
423 default definitions of PARM_DECLs. */
424 if (TREE_CODE (sym) == PARM_DECL
425 && POINTER_TYPE_P (TREE_TYPE (sym))
426 && nonnull_arg_p (sym))
427 set_value_range_to_nonnull (vr, TREE_TYPE (sym));
429 set_value_range_to_varying (vr);
435 /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */
438 vrp_operand_equal_p (tree val1, tree val2)
442 if (!val1 || !val2 || !operand_equal_p (val1, val2, 0))
444 if (is_overflow_infinity (val1))
445 return is_overflow_infinity (val2);
449 /* Return true, if the bitmaps B1 and B2 are equal. */
452 vrp_bitmap_equal_p (bitmap b1, bitmap b2)
456 && bitmap_equal_p (b1, b2)));
459 /* Update the value range and equivalence set for variable VAR to
460 NEW_VR. Return true if NEW_VR is different from VAR's previous
463 NOTE: This function assumes that NEW_VR is a temporary value range
464 object created for the sole purpose of updating VAR's range. The
465 storage used by the equivalence set from NEW_VR will be freed by
466 this function. Do not call update_value_range when NEW_VR
467 is the range object associated with another SSA name. */
470 update_value_range (tree var, value_range_t *new_vr)
472 value_range_t *old_vr;
475 /* Update the value range, if necessary. */
476 old_vr = get_value_range (var);
477 is_new = old_vr->type != new_vr->type
478 || !vrp_operand_equal_p (old_vr->min, new_vr->min)
479 || !vrp_operand_equal_p (old_vr->max, new_vr->max)
480 || !vrp_bitmap_equal_p (old_vr->equiv, new_vr->equiv);
483 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
486 BITMAP_FREE (new_vr->equiv);
487 new_vr->equiv = NULL;
493 /* Add VAR and VAR's equivalence set to EQUIV. */
496 add_equivalence (bitmap equiv, tree var)
498 unsigned ver = SSA_NAME_VERSION (var);
499 value_range_t *vr = vr_value[ver];
501 bitmap_set_bit (equiv, ver);
503 bitmap_ior_into (equiv, vr->equiv);
507 /* Return true if VR is ~[0, 0]. */
510 range_is_nonnull (value_range_t *vr)
512 return vr->type == VR_ANTI_RANGE
513 && integer_zerop (vr->min)
514 && integer_zerop (vr->max);
518 /* Return true if VR is [0, 0]. */
521 range_is_null (value_range_t *vr)
523 return vr->type == VR_RANGE
524 && integer_zerop (vr->min)
525 && integer_zerop (vr->max);
529 /* Return true if value range VR involves at least one symbol. */
532 symbolic_range_p (value_range_t *vr)
534 return (!is_gimple_min_invariant (vr->min)
535 || !is_gimple_min_invariant (vr->max));
538 /* Return true if value range VR uses a overflow infinity. */
541 overflow_infinity_range_p (value_range_t *vr)
543 return (vr->type == VR_RANGE
544 && (is_overflow_infinity (vr->min)
545 || is_overflow_infinity (vr->max)));
548 /* Return false if we can not make a valid comparison based on VR;
549 this will be the case if it uses an overflow infinity and overflow
550 is not undefined (i.e., -fno-strict-overflow is in effect).
551 Otherwise return true, and set *STRICT_OVERFLOW_P to true if VR
552 uses an overflow infinity. */
555 usable_range_p (value_range_t *vr, bool *strict_overflow_p)
557 gcc_assert (vr->type == VR_RANGE);
558 if (is_overflow_infinity (vr->min))
560 *strict_overflow_p = true;
561 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->min)))
564 if (is_overflow_infinity (vr->max))
566 *strict_overflow_p = true;
567 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->max)))
574 /* Like tree_expr_nonnegative_warnv_p, but this function uses value
575 ranges obtained so far. */
578 vrp_expr_computes_nonnegative (tree expr, bool *strict_overflow_p)
580 return tree_expr_nonnegative_warnv_p (expr, strict_overflow_p);
583 /* Like tree_expr_nonzero_warnv_p, but this function uses value ranges
587 vrp_expr_computes_nonzero (tree expr, bool *strict_overflow_p)
589 if (tree_expr_nonzero_warnv_p (expr, strict_overflow_p))
592 /* If we have an expression of the form &X->a, then the expression
593 is nonnull if X is nonnull. */
594 if (TREE_CODE (expr) == ADDR_EXPR)
596 tree base = get_base_address (TREE_OPERAND (expr, 0));
598 if (base != NULL_TREE
599 && TREE_CODE (base) == INDIRECT_REF
600 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
602 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
603 if (range_is_nonnull (vr))
611 /* Returns true if EXPR is a valid value (as expected by compare_values) --
612 a gimple invariant, or SSA_NAME +- CST. */
615 valid_value_p (tree expr)
617 if (TREE_CODE (expr) == SSA_NAME)
620 if (TREE_CODE (expr) == PLUS_EXPR
621 || TREE_CODE (expr) == MINUS_EXPR)
622 return (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME
623 && TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST);
625 return is_gimple_min_invariant (expr);
631 -2 if those are incomparable. */
633 operand_less_p (tree val, tree val2)
635 /* LT is folded faster than GE and others. Inline the common case. */
636 if (TREE_CODE (val) == INTEGER_CST && TREE_CODE (val2) == INTEGER_CST)
638 if (TYPE_UNSIGNED (TREE_TYPE (val)))
639 return INT_CST_LT_UNSIGNED (val, val2);
642 if (INT_CST_LT (val, val2))
650 fold_defer_overflow_warnings ();
652 tcmp = fold_binary_to_constant (LT_EXPR, boolean_type_node, val, val2);
654 fold_undefer_and_ignore_overflow_warnings ();
659 if (!integer_zerop (tcmp))
663 /* val >= val2, not considering overflow infinity. */
664 if (is_negative_overflow_infinity (val))
665 return is_negative_overflow_infinity (val2) ? 0 : 1;
666 else if (is_positive_overflow_infinity (val2))
667 return is_positive_overflow_infinity (val) ? 0 : 1;
672 /* Compare two values VAL1 and VAL2. Return
674 -2 if VAL1 and VAL2 cannot be compared at compile-time,
677 +1 if VAL1 > VAL2, and
680 This is similar to tree_int_cst_compare but supports pointer values
681 and values that cannot be compared at compile time.
683 If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to
684 true if the return value is only valid if we assume that signed
685 overflow is undefined. */
688 compare_values_warnv (tree val1, tree val2, bool *strict_overflow_p)
693 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
695 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
696 == POINTER_TYPE_P (TREE_TYPE (val2)));
698 if ((TREE_CODE (val1) == SSA_NAME
699 || TREE_CODE (val1) == PLUS_EXPR
700 || TREE_CODE (val1) == MINUS_EXPR)
701 && (TREE_CODE (val2) == SSA_NAME
702 || TREE_CODE (val2) == PLUS_EXPR
703 || TREE_CODE (val2) == MINUS_EXPR))
706 enum tree_code code1, code2;
708 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
709 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
710 same name, return -2. */
711 if (TREE_CODE (val1) == SSA_NAME)
719 code1 = TREE_CODE (val1);
720 n1 = TREE_OPERAND (val1, 0);
721 c1 = TREE_OPERAND (val1, 1);
722 if (tree_int_cst_sgn (c1) == -1)
724 if (is_negative_overflow_infinity (c1))
726 c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1);
729 code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
733 if (TREE_CODE (val2) == SSA_NAME)
741 code2 = TREE_CODE (val2);
742 n2 = TREE_OPERAND (val2, 0);
743 c2 = TREE_OPERAND (val2, 1);
744 if (tree_int_cst_sgn (c2) == -1)
746 if (is_negative_overflow_infinity (c2))
748 c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2);
751 code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
755 /* Both values must use the same name. */
759 if (code1 == SSA_NAME
760 && code2 == SSA_NAME)
764 /* If overflow is defined we cannot simplify more. */
765 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1)))
768 if (strict_overflow_p != NULL)
769 *strict_overflow_p = true;
771 if (code1 == SSA_NAME)
773 if (code2 == PLUS_EXPR)
774 /* NAME < NAME + CST */
776 else if (code2 == MINUS_EXPR)
777 /* NAME > NAME - CST */
780 else if (code1 == PLUS_EXPR)
782 if (code2 == SSA_NAME)
783 /* NAME + CST > NAME */
785 else if (code2 == PLUS_EXPR)
786 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
787 return compare_values_warnv (c1, c2, strict_overflow_p);
788 else if (code2 == MINUS_EXPR)
789 /* NAME + CST1 > NAME - CST2 */
792 else if (code1 == MINUS_EXPR)
794 if (code2 == SSA_NAME)
795 /* NAME - CST < NAME */
797 else if (code2 == PLUS_EXPR)
798 /* NAME - CST1 < NAME + CST2 */
800 else if (code2 == MINUS_EXPR)
801 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
802 C1 and C2 are swapped in the call to compare_values. */
803 return compare_values_warnv (c2, c1, strict_overflow_p);
809 /* We cannot compare non-constants. */
810 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
813 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
815 /* We cannot compare overflowed values, except for overflow
817 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
819 if (strict_overflow_p != NULL)
820 *strict_overflow_p = true;
821 if (is_negative_overflow_infinity (val1))
822 return is_negative_overflow_infinity (val2) ? 0 : -1;
823 else if (is_negative_overflow_infinity (val2))
825 else if (is_positive_overflow_infinity (val1))
826 return is_positive_overflow_infinity (val2) ? 0 : 1;
827 else if (is_positive_overflow_infinity (val2))
832 return tree_int_cst_compare (val1, val2);
838 /* First see if VAL1 and VAL2 are not the same. */
839 if (val1 == val2 || operand_equal_p (val1, val2, 0))
842 /* If VAL1 is a lower address than VAL2, return -1. */
843 if (operand_less_p (val1, val2) == 1)
846 /* If VAL1 is a higher address than VAL2, return +1. */
847 if (operand_less_p (val2, val1) == 1)
850 /* If VAL1 is different than VAL2, return +2.
851 For integer constants we either have already returned -1 or 1
852 or they are equivalent. We still might succeed in proving
853 something about non-trivial operands. */
854 if (TREE_CODE (val1) != INTEGER_CST
855 || TREE_CODE (val2) != INTEGER_CST)
857 t = fold_binary_to_constant (NE_EXPR, boolean_type_node, val1, val2);
858 if (t && tree_expr_nonzero_p (t))
866 /* Compare values like compare_values_warnv, but treat comparisons of
867 nonconstants which rely on undefined overflow as incomparable. */
870 compare_values (tree val1, tree val2)
876 ret = compare_values_warnv (val1, val2, &sop);
878 && (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2)))
884 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
885 0 if VAL is not inside VR,
886 -2 if we cannot tell either way.
888 FIXME, the current semantics of this functions are a bit quirky
889 when taken in the context of VRP. In here we do not care
890 about VR's type. If VR is the anti-range ~[3, 5] the call
891 value_inside_range (4, VR) will return 1.
893 This is counter-intuitive in a strict sense, but the callers
894 currently expect this. They are calling the function
895 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
896 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
899 This also applies to value_ranges_intersect_p and
900 range_includes_zero_p. The semantics of VR_RANGE and
901 VR_ANTI_RANGE should be encoded here, but that also means
902 adapting the users of these functions to the new semantics.
904 Benchmark compile/20001226-1.c compilation time after changing this
908 value_inside_range (tree val, value_range_t * vr)
912 cmp1 = operand_less_p (val, vr->min);
918 cmp2 = operand_less_p (vr->max, val);
926 /* Return true if value ranges VR0 and VR1 have a non-empty
929 Benchmark compile/20001226-1.c compilation time after changing this
934 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
936 /* The value ranges do not intersect if the maximum of the first range is
937 less than the minimum of the second range or vice versa.
938 When those relations are unknown, we can't do any better. */
939 if (operand_less_p (vr0->max, vr1->min) != 0)
941 if (operand_less_p (vr1->max, vr0->min) != 0)
947 /* Return true if VR includes the value zero, false otherwise. FIXME,
948 currently this will return false for an anti-range like ~[-4, 3].
949 This will be wrong when the semantics of value_inside_range are
950 modified (currently the users of this function expect these
954 range_includes_zero_p (value_range_t *vr)
958 gcc_assert (vr->type != VR_UNDEFINED
959 && vr->type != VR_VARYING
960 && !symbolic_range_p (vr));
962 zero = build_int_cst (TREE_TYPE (vr->min), 0);
963 return (value_inside_range (zero, vr) == 1);
966 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
967 false otherwise or if no value range information is available. */
970 ssa_name_nonnegative_p (tree t)
972 value_range_t *vr = get_value_range (t);
977 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
978 which would return a useful value should be encoded as a VR_RANGE. */
979 if (vr->type == VR_RANGE)
981 int result = compare_values (vr->min, integer_zero_node);
983 return (result == 0 || result == 1);
988 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
989 false otherwise or if no value range information is available. */
992 ssa_name_nonzero_p (tree t)
994 value_range_t *vr = get_value_range (t);
999 /* A VR_RANGE which does not include zero is a nonzero value. */
1000 if (vr->type == VR_RANGE && !symbolic_range_p (vr))
1001 return ! range_includes_zero_p (vr);
1003 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
1004 if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr))
1005 return range_includes_zero_p (vr);
1011 /* Extract value range information from an ASSERT_EXPR EXPR and store
1015 extract_range_from_assert (value_range_t *vr_p, tree expr)
1017 tree var, cond, limit, min, max, type;
1018 value_range_t *var_vr, *limit_vr;
1019 enum tree_code cond_code;
1021 var = ASSERT_EXPR_VAR (expr);
1022 cond = ASSERT_EXPR_COND (expr);
1024 gcc_assert (COMPARISON_CLASS_P (cond));
1026 /* Find VAR in the ASSERT_EXPR conditional. */
1027 if (var == TREE_OPERAND (cond, 0))
1029 /* If the predicate is of the form VAR COMP LIMIT, then we just
1030 take LIMIT from the RHS and use the same comparison code. */
1031 limit = TREE_OPERAND (cond, 1);
1032 cond_code = TREE_CODE (cond);
1036 /* If the predicate is of the form LIMIT COMP VAR, then we need
1037 to flip around the comparison code to create the proper range
1039 limit = TREE_OPERAND (cond, 0);
1040 cond_code = swap_tree_comparison (TREE_CODE (cond));
1043 type = TREE_TYPE (limit);
1044 gcc_assert (limit != var);
1046 /* For pointer arithmetic, we only keep track of pointer equality
1048 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
1050 set_value_range_to_varying (vr_p);
1054 /* If LIMIT is another SSA name and LIMIT has a range of its own,
1055 try to use LIMIT's range to avoid creating symbolic ranges
1057 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
1059 /* LIMIT's range is only interesting if it has any useful information. */
1061 && (limit_vr->type == VR_UNDEFINED
1062 || limit_vr->type == VR_VARYING
1063 || symbolic_range_p (limit_vr)))
1066 /* Initially, the new range has the same set of equivalences of
1067 VAR's range. This will be revised before returning the final
1068 value. Since assertions may be chained via mutually exclusive
1069 predicates, we will need to trim the set of equivalences before
1071 gcc_assert (vr_p->equiv == NULL);
1072 vr_p->equiv = BITMAP_ALLOC (NULL);
1073 add_equivalence (vr_p->equiv, var);
1075 /* Extract a new range based on the asserted comparison for VAR and
1076 LIMIT's value range. Notice that if LIMIT has an anti-range, we
1077 will only use it for equality comparisons (EQ_EXPR). For any
1078 other kind of assertion, we cannot derive a range from LIMIT's
1079 anti-range that can be used to describe the new range. For
1080 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
1081 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
1082 no single range for x_2 that could describe LE_EXPR, so we might
1083 as well build the range [b_4, +INF] for it. */
1084 if (cond_code == EQ_EXPR)
1086 enum value_range_type range_type;
1090 range_type = limit_vr->type;
1091 min = limit_vr->min;
1092 max = limit_vr->max;
1096 range_type = VR_RANGE;
1101 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
1103 /* When asserting the equality VAR == LIMIT and LIMIT is another
1104 SSA name, the new range will also inherit the equivalence set
1106 if (TREE_CODE (limit) == SSA_NAME)
1107 add_equivalence (vr_p->equiv, limit);
1109 else if (cond_code == NE_EXPR)
1111 /* As described above, when LIMIT's range is an anti-range and
1112 this assertion is an inequality (NE_EXPR), then we cannot
1113 derive anything from the anti-range. For instance, if
1114 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
1115 not imply that VAR's range is [0, 0]. So, in the case of
1116 anti-ranges, we just assert the inequality using LIMIT and
1119 If LIMIT_VR is a range, we can only use it to build a new
1120 anti-range if LIMIT_VR is a single-valued range. For
1121 instance, if LIMIT_VR is [0, 1], the predicate
1122 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
1123 Rather, it means that for value 0 VAR should be ~[0, 0]
1124 and for value 1, VAR should be ~[1, 1]. We cannot
1125 represent these ranges.
1127 The only situation in which we can build a valid
1128 anti-range is when LIMIT_VR is a single-valued range
1129 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
1130 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
1132 && limit_vr->type == VR_RANGE
1133 && compare_values (limit_vr->min, limit_vr->max) == 0)
1135 min = limit_vr->min;
1136 max = limit_vr->max;
1140 /* In any other case, we cannot use LIMIT's range to build a
1141 valid anti-range. */
1145 /* If MIN and MAX cover the whole range for their type, then
1146 just use the original LIMIT. */
1147 if (INTEGRAL_TYPE_P (type)
1148 && (min == TYPE_MIN_VALUE (type)
1149 || is_negative_overflow_infinity (min))
1150 && (max == TYPE_MAX_VALUE (type)
1151 || is_positive_overflow_infinity (max)))
1154 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
1156 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
1158 min = TYPE_MIN_VALUE (type);
1160 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
1164 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1165 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
1167 max = limit_vr->max;
1170 /* If the maximum value forces us to be out of bounds, simply punt.
1171 It would be pointless to try and do anything more since this
1172 all should be optimized away above us. */
1173 if ((cond_code == LT_EXPR
1174 && compare_values (max, min) == 0)
1175 || is_overflow_infinity (max))
1176 set_value_range_to_varying (vr_p);
1179 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
1180 if (cond_code == LT_EXPR)
1182 tree one = build_int_cst (type, 1);
1183 max = fold_build2 (MINUS_EXPR, type, max, one);
1186 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1189 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
1191 max = TYPE_MAX_VALUE (type);
1193 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
1197 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1198 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
1200 min = limit_vr->min;
1203 /* If the minimum value forces us to be out of bounds, simply punt.
1204 It would be pointless to try and do anything more since this
1205 all should be optimized away above us. */
1206 if ((cond_code == GT_EXPR
1207 && compare_values (min, max) == 0)
1208 || is_overflow_infinity (min))
1209 set_value_range_to_varying (vr_p);
1212 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
1213 if (cond_code == GT_EXPR)
1215 tree one = build_int_cst (type, 1);
1216 min = fold_build2 (PLUS_EXPR, type, min, one);
1219 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1225 /* If VAR already had a known range, it may happen that the new
1226 range we have computed and VAR's range are not compatible. For
1230 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
1232 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
1234 While the above comes from a faulty program, it will cause an ICE
1235 later because p_8 and p_6 will have incompatible ranges and at
1236 the same time will be considered equivalent. A similar situation
1240 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
1242 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
1244 Again i_6 and i_7 will have incompatible ranges. It would be
1245 pointless to try and do anything with i_7's range because
1246 anything dominated by 'if (i_5 < 5)' will be optimized away.
1247 Note, due to the wa in which simulation proceeds, the statement
1248 i_7 = ASSERT_EXPR <...> we would never be visited because the
1249 conditional 'if (i_5 < 5)' always evaluates to false. However,
1250 this extra check does not hurt and may protect against future
1251 changes to VRP that may get into a situation similar to the
1252 NULL pointer dereference example.
1254 Note that these compatibility tests are only needed when dealing
1255 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1256 are both anti-ranges, they will always be compatible, because two
1257 anti-ranges will always have a non-empty intersection. */
1259 var_vr = get_value_range (var);
1261 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1262 ranges or anti-ranges. */
1263 if (vr_p->type == VR_VARYING
1264 || vr_p->type == VR_UNDEFINED
1265 || var_vr->type == VR_VARYING
1266 || var_vr->type == VR_UNDEFINED
1267 || symbolic_range_p (vr_p)
1268 || symbolic_range_p (var_vr))
1271 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
1273 /* If the two ranges have a non-empty intersection, we can
1274 refine the resulting range. Since the assert expression
1275 creates an equivalency and at the same time it asserts a
1276 predicate, we can take the intersection of the two ranges to
1277 get better precision. */
1278 if (value_ranges_intersect_p (var_vr, vr_p))
1280 /* Use the larger of the two minimums. */
1281 if (compare_values (vr_p->min, var_vr->min) == -1)
1286 /* Use the smaller of the two maximums. */
1287 if (compare_values (vr_p->max, var_vr->max) == 1)
1292 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
1296 /* The two ranges do not intersect, set the new range to
1297 VARYING, because we will not be able to do anything
1298 meaningful with it. */
1299 set_value_range_to_varying (vr_p);
1302 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
1303 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
1305 /* A range and an anti-range will cancel each other only if
1306 their ends are the same. For instance, in the example above,
1307 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1308 so VR_P should be set to VR_VARYING. */
1309 if (compare_values (var_vr->min, vr_p->min) == 0
1310 && compare_values (var_vr->max, vr_p->max) == 0)
1311 set_value_range_to_varying (vr_p);
1314 tree min, max, anti_min, anti_max, real_min, real_max;
1317 /* We want to compute the logical AND of the two ranges;
1318 there are three cases to consider.
1321 1. The VR_ANTI_RANGE range is completely within the
1322 VR_RANGE and the endpoints of the ranges are
1323 different. In that case the resulting range
1324 should be whichever range is more precise.
1325 Typically that will be the VR_RANGE.
1327 2. The VR_ANTI_RANGE is completely disjoint from
1328 the VR_RANGE. In this case the resulting range
1329 should be the VR_RANGE.
1331 3. There is some overlap between the VR_ANTI_RANGE
1334 3a. If the high limit of the VR_ANTI_RANGE resides
1335 within the VR_RANGE, then the result is a new
1336 VR_RANGE starting at the high limit of the
1337 the VR_ANTI_RANGE + 1 and extending to the
1338 high limit of the original VR_RANGE.
1340 3b. If the low limit of the VR_ANTI_RANGE resides
1341 within the VR_RANGE, then the result is a new
1342 VR_RANGE starting at the low limit of the original
1343 VR_RANGE and extending to the low limit of the
1344 VR_ANTI_RANGE - 1. */
1345 if (vr_p->type == VR_ANTI_RANGE)
1347 anti_min = vr_p->min;
1348 anti_max = vr_p->max;
1349 real_min = var_vr->min;
1350 real_max = var_vr->max;
1354 anti_min = var_vr->min;
1355 anti_max = var_vr->max;
1356 real_min = vr_p->min;
1357 real_max = vr_p->max;
1361 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1362 not including any endpoints. */
1363 if (compare_values (anti_max, real_max) == -1
1364 && compare_values (anti_min, real_min) == 1)
1366 set_value_range (vr_p, VR_RANGE, real_min,
1367 real_max, vr_p->equiv);
1369 /* Case 2, VR_ANTI_RANGE completely disjoint from
1371 else if (compare_values (anti_min, real_max) == 1
1372 || compare_values (anti_max, real_min) == -1)
1374 set_value_range (vr_p, VR_RANGE, real_min,
1375 real_max, vr_p->equiv);
1377 /* Case 3a, the anti-range extends into the low
1378 part of the real range. Thus creating a new
1379 low for the real range. */
1380 else if (((cmp = compare_values (anti_max, real_min)) == 1
1382 && compare_values (anti_max, real_max) == -1)
1384 gcc_assert (!is_positive_overflow_infinity (anti_max));
1385 if (needs_overflow_infinity (TREE_TYPE (anti_max))
1386 && anti_max == TYPE_MAX_VALUE (TREE_TYPE (anti_max)))
1388 if (!supports_overflow_infinity (TREE_TYPE (var_vr->min)))
1390 set_value_range_to_varying (vr_p);
1393 min = positive_overflow_infinity (TREE_TYPE (var_vr->min));
1396 min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min),
1398 build_int_cst (TREE_TYPE (var_vr->min), 1));
1400 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1402 /* Case 3b, the anti-range extends into the high
1403 part of the real range. Thus creating a new
1404 higher for the real range. */
1405 else if (compare_values (anti_min, real_min) == 1
1406 && ((cmp = compare_values (anti_min, real_max)) == -1
1409 gcc_assert (!is_negative_overflow_infinity (anti_min));
1410 if (needs_overflow_infinity (TREE_TYPE (anti_min))
1411 && anti_min == TYPE_MIN_VALUE (TREE_TYPE (anti_min)))
1413 if (!supports_overflow_infinity (TREE_TYPE (var_vr->min)))
1415 set_value_range_to_varying (vr_p);
1418 max = negative_overflow_infinity (TREE_TYPE (var_vr->min));
1421 max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min),
1423 build_int_cst (TREE_TYPE (var_vr->min), 1));
1425 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1432 /* Extract range information from SSA name VAR and store it in VR. If
1433 VAR has an interesting range, use it. Otherwise, create the
1434 range [VAR, VAR] and return it. This is useful in situations where
1435 we may have conditionals testing values of VARYING names. For
1442 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1446 extract_range_from_ssa_name (value_range_t *vr, tree var)
1448 value_range_t *var_vr = get_value_range (var);
1450 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
1451 copy_value_range (vr, var_vr);
1453 set_value_range (vr, VR_RANGE, var, var, NULL);
1455 add_equivalence (vr->equiv, var);
1459 /* Wrapper around int_const_binop. If the operation overflows and we
1460 are not using wrapping arithmetic, then adjust the result to be
1461 -INF or +INF depending on CODE, VAL1 and VAL2. This can return
1462 NULL_TREE if we need to use an overflow infinity representation but
1463 the type does not support it. */
1466 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
1470 res = int_const_binop (code, val1, val2, 0);
1472 /* If we are not using wrapping arithmetic, operate symbolically
1473 on -INF and +INF. */
1474 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1)))
1476 int checkz = compare_values (res, val1);
1477 bool overflow = false;
1479 /* Ensure that res = val1 [+*] val2 >= val1
1480 or that res = val1 - val2 <= val1. */
1481 if ((code == PLUS_EXPR
1482 && !(checkz == 1 || checkz == 0))
1483 || (code == MINUS_EXPR
1484 && !(checkz == 0 || checkz == -1)))
1488 /* Checking for multiplication overflow is done by dividing the
1489 output of the multiplication by the first input of the
1490 multiplication. If the result of that division operation is
1491 not equal to the second input of the multiplication, then the
1492 multiplication overflowed. */
1493 else if (code == MULT_EXPR && !integer_zerop (val1))
1495 tree tmp = int_const_binop (TRUNC_DIV_EXPR,
1498 int check = compare_values (tmp, val2);
1506 res = copy_node (res);
1507 TREE_OVERFLOW (res) = 1;
1511 else if ((TREE_OVERFLOW (res)
1512 && !TREE_OVERFLOW (val1)
1513 && !TREE_OVERFLOW (val2))
1514 || is_overflow_infinity (val1)
1515 || is_overflow_infinity (val2))
1517 /* If the operation overflowed but neither VAL1 nor VAL2 are
1518 overflown, return -INF or +INF depending on the operation
1519 and the combination of signs of the operands. */
1520 int sgn1 = tree_int_cst_sgn (val1);
1521 int sgn2 = tree_int_cst_sgn (val2);
1523 if (needs_overflow_infinity (TREE_TYPE (res))
1524 && !supports_overflow_infinity (TREE_TYPE (res)))
1527 /* We have to punt on adding infinities of different signs,
1528 since we can't tell what the sign of the result should be.
1529 Likewise for subtracting infinities of the same sign. */
1530 if (((code == PLUS_EXPR && sgn1 != sgn2)
1531 || (code == MINUS_EXPR && sgn1 == sgn2))
1532 && is_overflow_infinity (val1)
1533 && is_overflow_infinity (val2))
1536 /* Don't try to handle division or shifting of infinities. */
1537 if ((code == TRUNC_DIV_EXPR
1538 || code == FLOOR_DIV_EXPR
1539 || code == CEIL_DIV_EXPR
1540 || code == EXACT_DIV_EXPR
1541 || code == ROUND_DIV_EXPR
1542 || code == RSHIFT_EXPR)
1543 && (is_overflow_infinity (val1)
1544 || is_overflow_infinity (val2)))
1547 /* Notice that we only need to handle the restricted set of
1548 operations handled by extract_range_from_binary_expr.
1549 Among them, only multiplication, addition and subtraction
1550 can yield overflow without overflown operands because we
1551 are working with integral types only... except in the
1552 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1553 for division too. */
1555 /* For multiplication, the sign of the overflow is given
1556 by the comparison of the signs of the operands. */
1557 if ((code == MULT_EXPR && sgn1 == sgn2)
1558 /* For addition, the operands must be of the same sign
1559 to yield an overflow. Its sign is therefore that
1560 of one of the operands, for example the first. For
1561 infinite operands X + -INF is negative, not positive. */
1562 || (code == PLUS_EXPR
1564 ? !is_negative_overflow_infinity (val2)
1565 : is_positive_overflow_infinity (val2)))
1566 /* For subtraction, non-infinite operands must be of
1567 different signs to yield an overflow. Its sign is
1568 therefore that of the first operand or the opposite of
1569 that of the second operand. A first operand of 0 counts
1570 as positive here, for the corner case 0 - (-INF), which
1571 overflows, but must yield +INF. For infinite operands 0
1572 - INF is negative, not positive. */
1573 || (code == MINUS_EXPR
1575 ? !is_positive_overflow_infinity (val2)
1576 : is_negative_overflow_infinity (val2)))
1577 /* We only get in here with positive shift count, so the
1578 overflow direction is the same as the sign of val1.
1579 Actually rshift does not overflow at all, but we only
1580 handle the case of shifting overflowed -INF and +INF. */
1581 || (code == RSHIFT_EXPR
1583 /* For division, the only case is -INF / -1 = +INF. */
1584 || code == TRUNC_DIV_EXPR
1585 || code == FLOOR_DIV_EXPR
1586 || code == CEIL_DIV_EXPR
1587 || code == EXACT_DIV_EXPR
1588 || code == ROUND_DIV_EXPR)
1589 return (needs_overflow_infinity (TREE_TYPE (res))
1590 ? positive_overflow_infinity (TREE_TYPE (res))
1591 : TYPE_MAX_VALUE (TREE_TYPE (res)));
1593 return (needs_overflow_infinity (TREE_TYPE (res))
1594 ? negative_overflow_infinity (TREE_TYPE (res))
1595 : TYPE_MIN_VALUE (TREE_TYPE (res)));
1602 /* Extract range information from a binary expression EXPR based on
1603 the ranges of each of its operands and the expression code. */
1606 extract_range_from_binary_expr (value_range_t *vr, tree expr)
1608 enum tree_code code = TREE_CODE (expr);
1609 enum value_range_type type;
1610 tree op0, op1, min, max;
1612 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1613 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
1615 /* Not all binary expressions can be applied to ranges in a
1616 meaningful way. Handle only arithmetic operations. */
1617 if (code != PLUS_EXPR
1618 && code != MINUS_EXPR
1619 && code != MULT_EXPR
1620 && code != TRUNC_DIV_EXPR
1621 && code != FLOOR_DIV_EXPR
1622 && code != CEIL_DIV_EXPR
1623 && code != EXACT_DIV_EXPR
1624 && code != ROUND_DIV_EXPR
1625 && code != RSHIFT_EXPR
1628 && code != BIT_AND_EXPR
1629 && code != TRUTH_ANDIF_EXPR
1630 && code != TRUTH_ORIF_EXPR
1631 && code != TRUTH_AND_EXPR
1632 && code != TRUTH_OR_EXPR)
1634 set_value_range_to_varying (vr);
1638 /* Get value ranges for each operand. For constant operands, create
1639 a new value range with the operand to simplify processing. */
1640 op0 = TREE_OPERAND (expr, 0);
1641 if (TREE_CODE (op0) == SSA_NAME)
1642 vr0 = *(get_value_range (op0));
1643 else if (is_gimple_min_invariant (op0))
1644 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
1646 set_value_range_to_varying (&vr0);
1648 op1 = TREE_OPERAND (expr, 1);
1649 if (TREE_CODE (op1) == SSA_NAME)
1650 vr1 = *(get_value_range (op1));
1651 else if (is_gimple_min_invariant (op1))
1652 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
1654 set_value_range_to_varying (&vr1);
1656 /* If either range is UNDEFINED, so is the result. */
1657 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
1659 set_value_range_to_undefined (vr);
1663 /* The type of the resulting value range defaults to VR0.TYPE. */
1666 /* Refuse to operate on VARYING ranges, ranges of different kinds
1667 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1668 because we may be able to derive a useful range even if one of
1669 the operands is VR_VARYING or symbolic range. TODO, we may be
1670 able to derive anti-ranges in some cases. */
1671 if (code != BIT_AND_EXPR
1672 && code != TRUTH_AND_EXPR
1673 && code != TRUTH_OR_EXPR
1674 && (vr0.type == VR_VARYING
1675 || vr1.type == VR_VARYING
1676 || vr0.type != vr1.type
1677 || symbolic_range_p (&vr0)
1678 || symbolic_range_p (&vr1)))
1680 set_value_range_to_varying (vr);
1684 /* Now evaluate the expression to determine the new range. */
1685 if (POINTER_TYPE_P (TREE_TYPE (expr))
1686 || POINTER_TYPE_P (TREE_TYPE (op0))
1687 || POINTER_TYPE_P (TREE_TYPE (op1)))
1689 /* For pointer types, we are really only interested in asserting
1690 whether the expression evaluates to non-NULL. FIXME, we used
1691 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1692 ivopts is generating expressions with pointer multiplication
1694 if (code == PLUS_EXPR)
1696 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
1697 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
1698 else if (range_is_null (&vr0) && range_is_null (&vr1))
1699 set_value_range_to_null (vr, TREE_TYPE (expr));
1701 set_value_range_to_varying (vr);
1705 /* Subtracting from a pointer, may yield 0, so just drop the
1706 resulting range to varying. */
1707 set_value_range_to_varying (vr);
1713 /* For integer ranges, apply the operation to each end of the
1714 range and see what we end up with. */
1715 if (code == TRUTH_ANDIF_EXPR
1716 || code == TRUTH_ORIF_EXPR
1717 || code == TRUTH_AND_EXPR
1718 || code == TRUTH_OR_EXPR)
1720 /* If one of the operands is zero, we know that the whole
1721 expression evaluates zero. */
1722 if (code == TRUTH_AND_EXPR
1723 && ((vr0.type == VR_RANGE
1724 && integer_zerop (vr0.min)
1725 && integer_zerop (vr0.max))
1726 || (vr1.type == VR_RANGE
1727 && integer_zerop (vr1.min)
1728 && integer_zerop (vr1.max))))
1731 min = max = build_int_cst (TREE_TYPE (expr), 0);
1733 /* If one of the operands is one, we know that the whole
1734 expression evaluates one. */
1735 else if (code == TRUTH_OR_EXPR
1736 && ((vr0.type == VR_RANGE
1737 && integer_onep (vr0.min)
1738 && integer_onep (vr0.max))
1739 || (vr1.type == VR_RANGE
1740 && integer_onep (vr1.min)
1741 && integer_onep (vr1.max))))
1744 min = max = build_int_cst (TREE_TYPE (expr), 1);
1746 else if (vr0.type != VR_VARYING
1747 && vr1.type != VR_VARYING
1748 && vr0.type == vr1.type
1749 && !symbolic_range_p (&vr0)
1750 && !overflow_infinity_range_p (&vr0)
1751 && !symbolic_range_p (&vr1)
1752 && !overflow_infinity_range_p (&vr1))
1754 /* Boolean expressions cannot be folded with int_const_binop. */
1755 min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min);
1756 max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max);
1760 /* The result of a TRUTH_*_EXPR is always true or false. */
1761 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
1765 else if (code == PLUS_EXPR
1767 || code == MAX_EXPR)
1769 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1770 VR_VARYING. It would take more effort to compute a precise
1771 range for such a case. For example, if we have op0 == 1 and
1772 op1 == -1 with their ranges both being ~[0,0], we would have
1773 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1774 Note that we are guaranteed to have vr0.type == vr1.type at
1776 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
1778 set_value_range_to_varying (vr);
1782 /* For operations that make the resulting range directly
1783 proportional to the original ranges, apply the operation to
1784 the same end of each range. */
1785 min = vrp_int_const_binop (code, vr0.min, vr1.min);
1786 max = vrp_int_const_binop (code, vr0.max, vr1.max);
1788 else if (code == MULT_EXPR
1789 || code == TRUNC_DIV_EXPR
1790 || code == FLOOR_DIV_EXPR
1791 || code == CEIL_DIV_EXPR
1792 || code == EXACT_DIV_EXPR
1793 || code == ROUND_DIV_EXPR
1794 || code == RSHIFT_EXPR)
1800 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1801 drop to VR_VARYING. It would take more effort to compute a
1802 precise range for such a case. For example, if we have
1803 op0 == 65536 and op1 == 65536 with their ranges both being
1804 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1805 we cannot claim that the product is in ~[0,0]. Note that we
1806 are guaranteed to have vr0.type == vr1.type at this
1808 if (code == MULT_EXPR
1809 && vr0.type == VR_ANTI_RANGE
1810 && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0)))
1812 set_value_range_to_varying (vr);
1816 /* If we have a RSHIFT_EXPR with a possibly negative shift
1817 count or an anti-range shift count drop to VR_VARYING.
1818 We currently cannot handle the overflow cases correctly. */
1819 if (code == RSHIFT_EXPR
1820 && (vr1.type == VR_ANTI_RANGE
1821 || !vrp_expr_computes_nonnegative (op1, &sop)))
1823 set_value_range_to_varying (vr);
1827 /* Multiplications and divisions are a bit tricky to handle,
1828 depending on the mix of signs we have in the two ranges, we
1829 need to operate on different values to get the minimum and
1830 maximum values for the new range. One approach is to figure
1831 out all the variations of range combinations and do the
1834 However, this involves several calls to compare_values and it
1835 is pretty convoluted. It's simpler to do the 4 operations
1836 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1837 MAX1) and then figure the smallest and largest values to form
1840 /* Divisions by zero result in a VARYING value. */
1841 if ((code != MULT_EXPR
1842 && code != RSHIFT_EXPR)
1843 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
1845 set_value_range_to_varying (vr);
1849 /* Compute the 4 cross operations. */
1851 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
1852 if (val[0] == NULL_TREE)
1855 if (vr1.max == vr1.min)
1859 val[1] = vrp_int_const_binop (code, vr0.min, vr1.max);
1860 if (val[1] == NULL_TREE)
1864 if (vr0.max == vr0.min)
1868 val[2] = vrp_int_const_binop (code, vr0.max, vr1.min);
1869 if (val[2] == NULL_TREE)
1873 if (vr0.min == vr0.max || vr1.min == vr1.max)
1877 val[3] = vrp_int_const_binop (code, vr0.max, vr1.max);
1878 if (val[3] == NULL_TREE)
1884 set_value_range_to_varying (vr);
1888 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1892 for (i = 1; i < 4; i++)
1894 if (!is_gimple_min_invariant (min)
1895 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
1896 || !is_gimple_min_invariant (max)
1897 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
1902 if (!is_gimple_min_invariant (val[i])
1903 || (TREE_OVERFLOW (val[i])
1904 && !is_overflow_infinity (val[i])))
1906 /* If we found an overflowed value, set MIN and MAX
1907 to it so that we set the resulting range to
1913 if (compare_values (val[i], min) == -1)
1916 if (compare_values (val[i], max) == 1)
1921 else if (code == MINUS_EXPR)
1923 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1924 VR_VARYING. It would take more effort to compute a precise
1925 range for such a case. For example, if we have op0 == 1 and
1926 op1 == 1 with their ranges both being ~[0,0], we would have
1927 op0 - op1 == 0, so we cannot claim that the difference is in
1928 ~[0,0]. Note that we are guaranteed to have
1929 vr0.type == vr1.type at this point. */
1930 if (vr0.type == VR_ANTI_RANGE)
1932 set_value_range_to_varying (vr);
1936 /* For MINUS_EXPR, apply the operation to the opposite ends of
1938 min = vrp_int_const_binop (code, vr0.min, vr1.max);
1939 max = vrp_int_const_binop (code, vr0.max, vr1.min);
1941 else if (code == BIT_AND_EXPR)
1943 if (vr0.type == VR_RANGE
1944 && vr0.min == vr0.max
1945 && TREE_CODE (vr0.max) == INTEGER_CST
1946 && !TREE_OVERFLOW (vr0.max)
1947 && tree_int_cst_sgn (vr0.max) >= 0)
1949 min = build_int_cst (TREE_TYPE (expr), 0);
1952 else if (vr1.type == VR_RANGE
1953 && vr1.min == vr1.max
1954 && TREE_CODE (vr1.max) == INTEGER_CST
1955 && !TREE_OVERFLOW (vr1.max)
1956 && tree_int_cst_sgn (vr1.max) >= 0)
1959 min = build_int_cst (TREE_TYPE (expr), 0);
1964 set_value_range_to_varying (vr);
1971 /* If either MIN or MAX overflowed, then set the resulting range to
1972 VARYING. But we do accept an overflow infinity
1974 if (min == NULL_TREE
1975 || !is_gimple_min_invariant (min)
1976 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
1978 || !is_gimple_min_invariant (max)
1979 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
1981 set_value_range_to_varying (vr);
1987 2) [-INF, +-INF(OVF)]
1988 3) [+-INF(OVF), +INF]
1989 4) [+-INF(OVF), +-INF(OVF)]
1990 We learn nothing when we have INF and INF(OVF) on both sides.
1991 Note that we do accept [-INF, -INF] and [+INF, +INF] without
1993 if ((min == TYPE_MIN_VALUE (TREE_TYPE (min))
1994 || is_overflow_infinity (min))
1995 && (max == TYPE_MAX_VALUE (TREE_TYPE (max))
1996 || is_overflow_infinity (max)))
1998 set_value_range_to_varying (vr);
2002 cmp = compare_values (min, max);
2003 if (cmp == -2 || cmp == 1)
2005 /* If the new range has its limits swapped around (MIN > MAX),
2006 then the operation caused one of them to wrap around, mark
2007 the new range VARYING. */
2008 set_value_range_to_varying (vr);
2011 set_value_range (vr, type, min, max, NULL);
2015 /* Extract range information from a unary expression EXPR based on
2016 the range of its operand and the expression code. */
2019 extract_range_from_unary_expr (value_range_t *vr, tree expr)
2021 enum tree_code code = TREE_CODE (expr);
2024 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2026 /* Refuse to operate on certain unary expressions for which we
2027 cannot easily determine a resulting range. */
2028 if (code == FIX_TRUNC_EXPR
2029 || code == FLOAT_EXPR
2030 || code == BIT_NOT_EXPR
2031 || code == NON_LVALUE_EXPR
2032 || code == CONJ_EXPR)
2034 set_value_range_to_varying (vr);
2038 /* Get value ranges for the operand. For constant operands, create
2039 a new value range with the operand to simplify processing. */
2040 op0 = TREE_OPERAND (expr, 0);
2041 if (TREE_CODE (op0) == SSA_NAME)
2042 vr0 = *(get_value_range (op0));
2043 else if (is_gimple_min_invariant (op0))
2044 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
2046 set_value_range_to_varying (&vr0);
2048 /* If VR0 is UNDEFINED, so is the result. */
2049 if (vr0.type == VR_UNDEFINED)
2051 set_value_range_to_undefined (vr);
2055 /* Refuse to operate on symbolic ranges, or if neither operand is
2056 a pointer or integral type. */
2057 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0))
2058 && !POINTER_TYPE_P (TREE_TYPE (op0)))
2059 || (vr0.type != VR_VARYING
2060 && symbolic_range_p (&vr0)))
2062 set_value_range_to_varying (vr);
2066 /* If the expression involves pointers, we are only interested in
2067 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
2068 if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0)))
2073 if (range_is_nonnull (&vr0)
2074 || (tree_expr_nonzero_warnv_p (expr, &sop)
2076 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
2077 else if (range_is_null (&vr0))
2078 set_value_range_to_null (vr, TREE_TYPE (expr));
2080 set_value_range_to_varying (vr);
2085 /* Handle unary expressions on integer ranges. */
2086 if (code == NOP_EXPR || code == CONVERT_EXPR)
2088 tree inner_type = TREE_TYPE (op0);
2089 tree outer_type = TREE_TYPE (expr);
2091 /* If VR0 represents a simple range, then try to convert
2092 the min and max values for the range to the same type
2093 as OUTER_TYPE. If the results compare equal to VR0's
2094 min and max values and the new min is still less than
2095 or equal to the new max, then we can safely use the newly
2096 computed range for EXPR. This allows us to compute
2097 accurate ranges through many casts. */
2098 if ((vr0.type == VR_RANGE
2099 && !overflow_infinity_range_p (&vr0))
2100 || (vr0.type == VR_VARYING
2101 && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type)))
2103 tree new_min, new_max, orig_min, orig_max;
2105 /* Convert the input operand min/max to OUTER_TYPE. If
2106 the input has no range information, then use the min/max
2107 for the input's type. */
2108 if (vr0.type == VR_RANGE)
2115 orig_min = TYPE_MIN_VALUE (inner_type);
2116 orig_max = TYPE_MAX_VALUE (inner_type);
2119 new_min = fold_convert (outer_type, orig_min);
2120 new_max = fold_convert (outer_type, orig_max);
2122 /* Verify the new min/max values are gimple values and
2123 that they compare equal to the original input's
2125 if (is_gimple_val (new_min)
2126 && is_gimple_val (new_max)
2127 && tree_int_cst_equal (new_min, orig_min)
2128 && tree_int_cst_equal (new_max, orig_max)
2129 && (cmp = compare_values (new_min, new_max)) <= 0
2132 set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv);
2137 /* When converting types of different sizes, set the result to
2138 VARYING. Things like sign extensions and precision loss may
2139 change the range. For instance, if x_3 is of type 'long long
2140 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
2141 is impossible to know at compile time whether y_5 will be
2143 if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type)
2144 || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type))
2146 set_value_range_to_varying (vr);
2151 /* Conversion of a VR_VARYING value to a wider type can result
2152 in a usable range. So wait until after we've handled conversions
2153 before dropping the result to VR_VARYING if we had a source
2154 operand that is VR_VARYING. */
2155 if (vr0.type == VR_VARYING)
2157 set_value_range_to_varying (vr);
2161 /* Apply the operation to each end of the range and see what we end
2163 if (code == NEGATE_EXPR
2164 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
2166 /* NEGATE_EXPR flips the range around. We need to treat
2167 TYPE_MIN_VALUE specially. */
2168 if (is_positive_overflow_infinity (vr0.max))
2169 min = negative_overflow_infinity (TREE_TYPE (expr));
2170 else if (is_negative_overflow_infinity (vr0.max))
2171 min = positive_overflow_infinity (TREE_TYPE (expr));
2172 else if (vr0.max != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2173 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2174 else if (needs_overflow_infinity (TREE_TYPE (expr)))
2176 if (supports_overflow_infinity (TREE_TYPE (expr)))
2177 min = positive_overflow_infinity (TREE_TYPE (expr));
2180 set_value_range_to_varying (vr);
2185 min = TYPE_MIN_VALUE (TREE_TYPE (expr));
2187 if (is_positive_overflow_infinity (vr0.min))
2188 max = negative_overflow_infinity (TREE_TYPE (expr));
2189 else if (is_negative_overflow_infinity (vr0.min))
2190 max = positive_overflow_infinity (TREE_TYPE (expr));
2191 else if (vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2192 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2193 else if (needs_overflow_infinity (TREE_TYPE (expr)))
2195 if (supports_overflow_infinity (TREE_TYPE (expr)))
2196 max = positive_overflow_infinity (TREE_TYPE (expr));
2199 set_value_range_to_varying (vr);
2204 max = TYPE_MIN_VALUE (TREE_TYPE (expr));
2206 else if (code == NEGATE_EXPR
2207 && TYPE_UNSIGNED (TREE_TYPE (expr)))
2209 if (!range_includes_zero_p (&vr0))
2211 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2212 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2216 if (range_is_null (&vr0))
2217 set_value_range_to_null (vr, TREE_TYPE (expr));
2219 set_value_range_to_varying (vr);
2223 else if (code == ABS_EXPR
2224 && !TYPE_UNSIGNED (TREE_TYPE (expr)))
2226 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
2228 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (expr))
2229 && ((vr0.type == VR_RANGE
2230 && vr0.min == TYPE_MIN_VALUE (TREE_TYPE (expr)))
2231 || (vr0.type == VR_ANTI_RANGE
2232 && vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr))
2233 && !range_includes_zero_p (&vr0))))
2235 set_value_range_to_varying (vr);
2239 /* ABS_EXPR may flip the range around, if the original range
2240 included negative values. */
2241 if (is_overflow_infinity (vr0.min))
2242 min = positive_overflow_infinity (TREE_TYPE (expr));
2243 else if (vr0.min != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2244 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2245 else if (!needs_overflow_infinity (TREE_TYPE (expr)))
2246 min = TYPE_MAX_VALUE (TREE_TYPE (expr));
2247 else if (supports_overflow_infinity (TREE_TYPE (expr)))
2248 min = positive_overflow_infinity (TREE_TYPE (expr));
2251 set_value_range_to_varying (vr);
2255 if (is_overflow_infinity (vr0.max))
2256 max = positive_overflow_infinity (TREE_TYPE (expr));
2257 else if (vr0.max != TYPE_MIN_VALUE (TREE_TYPE (expr)))
2258 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2259 else if (!needs_overflow_infinity (TREE_TYPE (expr)))
2260 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
2261 else if (supports_overflow_infinity (TREE_TYPE (expr)))
2262 max = positive_overflow_infinity (TREE_TYPE (expr));
2265 set_value_range_to_varying (vr);
2269 cmp = compare_values (min, max);
2271 /* If a VR_ANTI_RANGEs contains zero, then we have
2272 ~[-INF, min(MIN, MAX)]. */
2273 if (vr0.type == VR_ANTI_RANGE)
2275 if (range_includes_zero_p (&vr0))
2277 /* Take the lower of the two values. */
2281 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
2282 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
2283 flag_wrapv is set and the original anti-range doesn't include
2284 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
2285 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr)))
2287 tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr));
2289 min = (vr0.min != type_min_value
2290 ? int_const_binop (PLUS_EXPR, type_min_value,
2291 integer_one_node, 0)
2296 if (overflow_infinity_range_p (&vr0))
2297 min = negative_overflow_infinity (TREE_TYPE (expr));
2299 min = TYPE_MIN_VALUE (TREE_TYPE (expr));
2304 /* All else has failed, so create the range [0, INF], even for
2305 flag_wrapv since TYPE_MIN_VALUE is in the original
2307 vr0.type = VR_RANGE;
2308 min = build_int_cst (TREE_TYPE (expr), 0);
2309 if (needs_overflow_infinity (TREE_TYPE (expr)))
2311 if (supports_overflow_infinity (TREE_TYPE (expr)))
2312 max = positive_overflow_infinity (TREE_TYPE (expr));
2315 set_value_range_to_varying (vr);
2320 max = TYPE_MAX_VALUE (TREE_TYPE (expr));
2324 /* If the range contains zero then we know that the minimum value in the
2325 range will be zero. */
2326 else if (range_includes_zero_p (&vr0))
2330 min = build_int_cst (TREE_TYPE (expr), 0);
2334 /* If the range was reversed, swap MIN and MAX. */
2345 /* Otherwise, operate on each end of the range. */
2346 min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min);
2347 max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max);
2349 if (needs_overflow_infinity (TREE_TYPE (expr)))
2351 gcc_assert (code != NEGATE_EXPR && code != ABS_EXPR);
2352 if (is_overflow_infinity (vr0.min))
2354 else if (TREE_OVERFLOW (min))
2356 if (supports_overflow_infinity (TREE_TYPE (expr)))
2357 min = (tree_int_cst_sgn (min) >= 0
2358 ? positive_overflow_infinity (TREE_TYPE (min))
2359 : negative_overflow_infinity (TREE_TYPE (min)));
2362 set_value_range_to_varying (vr);
2367 if (is_overflow_infinity (vr0.max))
2369 else if (TREE_OVERFLOW (max))
2371 if (supports_overflow_infinity (TREE_TYPE (expr)))
2372 max = (tree_int_cst_sgn (max) >= 0
2373 ? positive_overflow_infinity (TREE_TYPE (max))
2374 : negative_overflow_infinity (TREE_TYPE (max)));
2377 set_value_range_to_varying (vr);
2384 cmp = compare_values (min, max);
2385 if (cmp == -2 || cmp == 1)
2387 /* If the new range has its limits swapped around (MIN > MAX),
2388 then the operation caused one of them to wrap around, mark
2389 the new range VARYING. */
2390 set_value_range_to_varying (vr);
2393 set_value_range (vr, vr0.type, min, max, NULL);
2397 /* Extract range information from a conditional expression EXPR based on
2398 the ranges of each of its operands and the expression code. */
2401 extract_range_from_cond_expr (value_range_t *vr, tree expr)
2404 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2405 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2407 /* Get value ranges for each operand. For constant operands, create
2408 a new value range with the operand to simplify processing. */
2409 op0 = COND_EXPR_THEN (expr);
2410 if (TREE_CODE (op0) == SSA_NAME)
2411 vr0 = *(get_value_range (op0));
2412 else if (is_gimple_min_invariant (op0))
2413 set_value_range (&vr0, VR_RANGE, op0, op0, NULL);
2415 set_value_range_to_varying (&vr0);
2417 op1 = COND_EXPR_ELSE (expr);
2418 if (TREE_CODE (op1) == SSA_NAME)
2419 vr1 = *(get_value_range (op1));
2420 else if (is_gimple_min_invariant (op1))
2421 set_value_range (&vr1, VR_RANGE, op1, op1, NULL);
2423 set_value_range_to_varying (&vr1);
2425 /* The resulting value range is the union of the operand ranges */
2426 vrp_meet (&vr0, &vr1);
2427 copy_value_range (vr, &vr0);
2431 /* Extract range information from a comparison expression EXPR based
2432 on the range of its operand and the expression code. */
2435 extract_range_from_comparison (value_range_t *vr, tree expr)
2438 tree val = vrp_evaluate_conditional_warnv (expr, false, &sop);
2440 /* A disadvantage of using a special infinity as an overflow
2441 representation is that we lose the ability to record overflow
2442 when we don't have an infinity. So we have to ignore a result
2443 which relies on overflow. */
2445 if (val && !is_overflow_infinity (val) && !sop)
2447 /* Since this expression was found on the RHS of an assignment,
2448 its type may be different from _Bool. Convert VAL to EXPR's
2450 val = fold_convert (TREE_TYPE (expr), val);
2451 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
2454 /* The result of a comparison is always true or false. */
2455 set_value_range_to_truthvalue (vr, TREE_TYPE (expr));
2459 /* Try to compute a useful range out of expression EXPR and store it
2463 extract_range_from_expr (value_range_t *vr, tree expr)
2465 enum tree_code code = TREE_CODE (expr);
2467 if (code == ASSERT_EXPR)
2468 extract_range_from_assert (vr, expr);
2469 else if (code == SSA_NAME)
2470 extract_range_from_ssa_name (vr, expr);
2471 else if (TREE_CODE_CLASS (code) == tcc_binary
2472 || code == TRUTH_ANDIF_EXPR
2473 || code == TRUTH_ORIF_EXPR
2474 || code == TRUTH_AND_EXPR
2475 || code == TRUTH_OR_EXPR
2476 || code == TRUTH_XOR_EXPR)
2477 extract_range_from_binary_expr (vr, expr);
2478 else if (TREE_CODE_CLASS (code) == tcc_unary)
2479 extract_range_from_unary_expr (vr, expr);
2480 else if (code == COND_EXPR)
2481 extract_range_from_cond_expr (vr, expr);
2482 else if (TREE_CODE_CLASS (code) == tcc_comparison)
2483 extract_range_from_comparison (vr, expr);
2484 else if (is_gimple_min_invariant (expr))
2485 set_value_range (vr, VR_RANGE, expr, expr, NULL);
2487 set_value_range_to_varying (vr);
2489 /* If we got a varying range from the tests above, try a final
2490 time to derive a nonnegative or nonzero range. This time
2491 relying primarily on generic routines in fold in conjunction
2493 if (vr->type == VR_VARYING)
2497 if (INTEGRAL_TYPE_P (TREE_TYPE (expr))
2498 && vrp_expr_computes_nonnegative (expr, &sop))
2499 set_value_range_to_nonnegative (vr, TREE_TYPE (expr),
2500 sop || is_overflow_infinity (expr));
2501 else if (vrp_expr_computes_nonzero (expr, &sop)
2503 set_value_range_to_nonnull (vr, TREE_TYPE (expr));
2507 /* Given a range VR, a LOOP and a variable VAR, determine whether it
2508 would be profitable to adjust VR using scalar evolution information
2509 for VAR. If so, update VR with the new limits. */
2512 adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt,
2515 tree init, step, chrec, tmin, tmax, min, max, type;
2516 enum ev_direction dir;
2518 /* TODO. Don't adjust anti-ranges. An anti-range may provide
2519 better opportunities than a regular range, but I'm not sure. */
2520 if (vr->type == VR_ANTI_RANGE)
2523 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
2524 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
2527 init = initial_condition_in_loop_num (chrec, loop->num);
2528 step = evolution_part_in_loop_num (chrec, loop->num);
2530 /* If STEP is symbolic, we can't know whether INIT will be the
2531 minimum or maximum value in the range. Also, unless INIT is
2532 a simple expression, compare_values and possibly other functions
2533 in tree-vrp won't be able to handle it. */
2534 if (step == NULL_TREE
2535 || !is_gimple_min_invariant (step)
2536 || !valid_value_p (init))
2539 dir = scev_direction (chrec);
2540 if (/* Do not adjust ranges if we do not know whether the iv increases
2541 or decreases, ... */
2542 dir == EV_DIR_UNKNOWN
2543 /* ... or if it may wrap. */
2544 || scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec),
2548 /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of
2549 negative_overflow_infinity and positive_overflow_infinity,
2550 because we have concluded that the loop probably does not
2553 type = TREE_TYPE (var);
2554 if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type))
2555 tmin = lower_bound_in_type (type, type);
2557 tmin = TYPE_MIN_VALUE (type);
2558 if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type))
2559 tmax = upper_bound_in_type (type, type);
2561 tmax = TYPE_MAX_VALUE (type);
2563 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2568 /* For VARYING or UNDEFINED ranges, just about anything we get
2569 from scalar evolutions should be better. */
2571 if (dir == EV_DIR_DECREASES)
2576 /* If we would create an invalid range, then just assume we
2577 know absolutely nothing. This may be over-conservative,
2578 but it's clearly safe, and should happen only in unreachable
2579 parts of code, or for invalid programs. */
2580 if (compare_values (min, max) == 1)
2583 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2585 else if (vr->type == VR_RANGE)
2590 if (dir == EV_DIR_DECREASES)
2592 /* INIT is the maximum value. If INIT is lower than VR->MAX
2593 but no smaller than VR->MIN, set VR->MAX to INIT. */
2594 if (compare_values (init, max) == -1)
2598 /* If we just created an invalid range with the minimum
2599 greater than the maximum, we fail conservatively.
2600 This should happen only in unreachable
2601 parts of code, or for invalid programs. */
2602 if (compare_values (min, max) == 1)
2608 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2609 if (compare_values (init, min) == 1)
2613 /* Again, avoid creating invalid range by failing. */
2614 if (compare_values (min, max) == 1)
2619 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
2624 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2626 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2627 all the values in the ranges.
2629 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2631 - Return NULL_TREE if it is not always possible to determine the
2632 value of the comparison.
2634 Also set *STRICT_OVERFLOW_P to indicate whether a range with an
2635 overflow infinity was used in the test. */
2639 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1,
2640 bool *strict_overflow_p)
2642 /* VARYING or UNDEFINED ranges cannot be compared. */
2643 if (vr0->type == VR_VARYING
2644 || vr0->type == VR_UNDEFINED
2645 || vr1->type == VR_VARYING
2646 || vr1->type == VR_UNDEFINED)
2649 /* Anti-ranges need to be handled separately. */
2650 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
2652 /* If both are anti-ranges, then we cannot compute any
2654 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
2657 /* These comparisons are never statically computable. */
2664 /* Equality can be computed only between a range and an
2665 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2666 if (vr0->type == VR_RANGE)
2668 /* To simplify processing, make VR0 the anti-range. */
2669 value_range_t *tmp = vr0;
2674 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
2676 if (compare_values_warnv (vr0->min, vr1->min, strict_overflow_p) == 0
2677 && compare_values_warnv (vr0->max, vr1->max, strict_overflow_p) == 0)
2678 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2683 if (!usable_range_p (vr0, strict_overflow_p)
2684 || !usable_range_p (vr1, strict_overflow_p))
2687 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2688 operands around and change the comparison code. */
2689 if (comp == GT_EXPR || comp == GE_EXPR)
2692 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
2698 if (comp == EQ_EXPR)
2700 /* Equality may only be computed if both ranges represent
2701 exactly one value. */
2702 if (compare_values_warnv (vr0->min, vr0->max, strict_overflow_p) == 0
2703 && compare_values_warnv (vr1->min, vr1->max, strict_overflow_p) == 0)
2705 int cmp_min = compare_values_warnv (vr0->min, vr1->min,
2707 int cmp_max = compare_values_warnv (vr0->max, vr1->max,
2709 if (cmp_min == 0 && cmp_max == 0)
2710 return boolean_true_node;
2711 else if (cmp_min != -2 && cmp_max != -2)
2712 return boolean_false_node;
2714 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2715 else if (compare_values_warnv (vr0->min, vr1->max,
2716 strict_overflow_p) == 1
2717 || compare_values_warnv (vr1->min, vr0->max,
2718 strict_overflow_p) == 1)
2719 return boolean_false_node;
2723 else if (comp == NE_EXPR)
2727 /* If VR0 is completely to the left or completely to the right
2728 of VR1, they are always different. Notice that we need to
2729 make sure that both comparisons yield similar results to
2730 avoid comparing values that cannot be compared at
2732 cmp1 = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
2733 cmp2 = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
2734 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
2735 return boolean_true_node;
2737 /* If VR0 and VR1 represent a single value and are identical,
2739 else if (compare_values_warnv (vr0->min, vr0->max,
2740 strict_overflow_p) == 0
2741 && compare_values_warnv (vr1->min, vr1->max,
2742 strict_overflow_p) == 0
2743 && compare_values_warnv (vr0->min, vr1->min,
2744 strict_overflow_p) == 0
2745 && compare_values_warnv (vr0->max, vr1->max,
2746 strict_overflow_p) == 0)
2747 return boolean_false_node;
2749 /* Otherwise, they may or may not be different. */
2753 else if (comp == LT_EXPR || comp == LE_EXPR)
2757 /* If VR0 is to the left of VR1, return true. */
2758 tst = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
2759 if ((comp == LT_EXPR && tst == -1)
2760 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2762 if (overflow_infinity_range_p (vr0)
2763 || overflow_infinity_range_p (vr1))
2764 *strict_overflow_p = true;
2765 return boolean_true_node;
2768 /* If VR0 is to the right of VR1, return false. */
2769 tst = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
2770 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2771 || (comp == LE_EXPR && tst == 1))
2773 if (overflow_infinity_range_p (vr0)
2774 || overflow_infinity_range_p (vr1))
2775 *strict_overflow_p = true;
2776 return boolean_false_node;
2779 /* Otherwise, we don't know. */
2787 /* Given a value range VR, a value VAL and a comparison code COMP, return
2788 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2789 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2790 always returns false. Return NULL_TREE if it is not always
2791 possible to determine the value of the comparison. Also set
2792 *STRICT_OVERFLOW_P to indicate whether a range with an overflow
2793 infinity was used in the test. */
2796 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val,
2797 bool *strict_overflow_p)
2799 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
2802 /* Anti-ranges need to be handled separately. */
2803 if (vr->type == VR_ANTI_RANGE)
2805 /* For anti-ranges, the only predicates that we can compute at
2806 compile time are equality and inequality. */
2813 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2814 if (value_inside_range (val, vr) == 1)
2815 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
2820 if (!usable_range_p (vr, strict_overflow_p))
2823 if (comp == EQ_EXPR)
2825 /* EQ_EXPR may only be computed if VR represents exactly
2827 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0)
2829 int cmp = compare_values_warnv (vr->min, val, strict_overflow_p);
2831 return boolean_true_node;
2832 else if (cmp == -1 || cmp == 1 || cmp == 2)
2833 return boolean_false_node;
2835 else if (compare_values_warnv (val, vr->min, strict_overflow_p) == -1
2836 || compare_values_warnv (vr->max, val, strict_overflow_p) == -1)
2837 return boolean_false_node;
2841 else if (comp == NE_EXPR)
2843 /* If VAL is not inside VR, then they are always different. */
2844 if (compare_values_warnv (vr->max, val, strict_overflow_p) == -1
2845 || compare_values_warnv (vr->min, val, strict_overflow_p) == 1)
2846 return boolean_true_node;
2848 /* If VR represents exactly one value equal to VAL, then return
2850 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0
2851 && compare_values_warnv (vr->min, val, strict_overflow_p) == 0)
2852 return boolean_false_node;
2854 /* Otherwise, they may or may not be different. */
2857 else if (comp == LT_EXPR || comp == LE_EXPR)
2861 /* If VR is to the left of VAL, return true. */
2862 tst = compare_values_warnv (vr->max, val, strict_overflow_p);
2863 if ((comp == LT_EXPR && tst == -1)
2864 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
2866 if (overflow_infinity_range_p (vr))
2867 *strict_overflow_p = true;
2868 return boolean_true_node;
2871 /* If VR is to the right of VAL, return false. */
2872 tst = compare_values_warnv (vr->min, val, strict_overflow_p);
2873 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
2874 || (comp == LE_EXPR && tst == 1))
2876 if (overflow_infinity_range_p (vr))
2877 *strict_overflow_p = true;
2878 return boolean_false_node;
2881 /* Otherwise, we don't know. */
2884 else if (comp == GT_EXPR || comp == GE_EXPR)
2888 /* If VR is to the right of VAL, return true. */
2889 tst = compare_values_warnv (vr->min, val, strict_overflow_p);
2890 if ((comp == GT_EXPR && tst == 1)
2891 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
2893 if (overflow_infinity_range_p (vr))
2894 *strict_overflow_p = true;
2895 return boolean_true_node;
2898 /* If VR is to the left of VAL, return false. */
2899 tst = compare_values_warnv (vr->max, val, strict_overflow_p);
2900 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
2901 || (comp == GE_EXPR && tst == -1))
2903 if (overflow_infinity_range_p (vr))
2904 *strict_overflow_p = true;
2905 return boolean_false_node;
2908 /* Otherwise, we don't know. */
2916 /* Debugging dumps. */
2918 void dump_value_range (FILE *, value_range_t *);
2919 void debug_value_range (value_range_t *);
2920 void dump_all_value_ranges (FILE *);
2921 void debug_all_value_ranges (void);
2922 void dump_vr_equiv (FILE *, bitmap);
2923 void debug_vr_equiv (bitmap);
2926 /* Dump value range VR to FILE. */
2929 dump_value_range (FILE *file, value_range_t *vr)
2932 fprintf (file, "[]");
2933 else if (vr->type == VR_UNDEFINED)
2934 fprintf (file, "UNDEFINED");
2935 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
2937 tree type = TREE_TYPE (vr->min);
2939 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
2941 if (INTEGRAL_TYPE_P (type)
2942 && !TYPE_UNSIGNED (type)
2943 && vr->min == TYPE_MIN_VALUE (type))
2944 fprintf (file, "-INF");
2945 else if (needs_overflow_infinity (type)
2946 && is_negative_overflow_infinity (vr->min))
2947 fprintf (file, "-INF(OVF)");
2949 print_generic_expr (file, vr->min, 0);
2951 fprintf (file, ", ");
2953 if (INTEGRAL_TYPE_P (type)
2954 && vr->max == TYPE_MAX_VALUE (type))
2955 fprintf (file, "+INF");
2956 else if (needs_overflow_infinity (type)
2957 && is_positive_overflow_infinity (vr->max))
2958 fprintf (file, "+INF(OVF)");
2960 print_generic_expr (file, vr->max, 0);
2962 fprintf (file, "]");
2969 fprintf (file, " EQUIVALENCES: { ");
2971 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
2973 print_generic_expr (file, ssa_name (i), 0);
2974 fprintf (file, " ");
2978 fprintf (file, "} (%u elements)", c);
2981 else if (vr->type == VR_VARYING)
2982 fprintf (file, "VARYING");
2984 fprintf (file, "INVALID RANGE");
2988 /* Dump value range VR to stderr. */
2991 debug_value_range (value_range_t *vr)
2993 dump_value_range (stderr, vr);
2994 fprintf (stderr, "\n");
2998 /* Dump value ranges of all SSA_NAMEs to FILE. */
3001 dump_all_value_ranges (FILE *file)
3005 for (i = 0; i < num_ssa_names; i++)
3009 print_generic_expr (file, ssa_name (i), 0);
3010 fprintf (file, ": ");
3011 dump_value_range (file, vr_value[i]);
3012 fprintf (file, "\n");
3016 fprintf (file, "\n");
3020 /* Dump all value ranges to stderr. */
3023 debug_all_value_ranges (void)
3025 dump_all_value_ranges (stderr);
3029 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
3030 create a new SSA name N and return the assertion assignment
3031 'V = ASSERT_EXPR <V, V OP W>'. */
3034 build_assert_expr_for (tree cond, tree v)
3038 gcc_assert (TREE_CODE (v) == SSA_NAME);
3039 n = duplicate_ssa_name (v, NULL_TREE);
3041 if (COMPARISON_CLASS_P (cond))
3043 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
3044 assertion = build_gimple_modify_stmt (n, a);
3046 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
3048 /* Given !V, build the assignment N = false. */
3049 tree op0 = TREE_OPERAND (cond, 0);
3050 gcc_assert (op0 == v);
3051 assertion = build_gimple_modify_stmt (n, boolean_false_node);
3053 else if (TREE_CODE (cond) == SSA_NAME)
3055 /* Given V, build the assignment N = true. */
3056 gcc_assert (v == cond);
3057 assertion = build_gimple_modify_stmt (n, boolean_true_node);
3062 SSA_NAME_DEF_STMT (n) = assertion;
3064 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
3065 operand of the ASSERT_EXPR. Register the new name and the old one
3066 in the replacement table so that we can fix the SSA web after
3067 adding all the ASSERT_EXPRs. */
3068 register_new_name_mapping (n, v);
3074 /* Return false if EXPR is a predicate expression involving floating
3078 fp_predicate (tree expr)
3080 return (COMPARISON_CLASS_P (expr)
3081 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))));
3085 /* If the range of values taken by OP can be inferred after STMT executes,
3086 return the comparison code (COMP_CODE_P) and value (VAL_P) that
3087 describes the inferred range. Return true if a range could be
3091 infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
3094 *comp_code_p = ERROR_MARK;
3096 /* Do not attempt to infer anything in names that flow through
3098 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
3101 /* Similarly, don't infer anything from statements that may throw
3103 if (tree_could_throw_p (stmt))
3106 /* If STMT is the last statement of a basic block with no
3107 successors, there is no point inferring anything about any of its
3108 operands. We would not be able to find a proper insertion point
3109 for the assertion, anyway. */
3110 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0)
3113 /* We can only assume that a pointer dereference will yield
3114 non-NULL if -fdelete-null-pointer-checks is enabled. */
3115 if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op)))
3118 unsigned num_uses, num_derefs;
3120 count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store);
3123 *val_p = build_int_cst (TREE_TYPE (op), 0);
3124 *comp_code_p = NE_EXPR;
3133 void dump_asserts_for (FILE *, tree);
3134 void debug_asserts_for (tree);
3135 void dump_all_asserts (FILE *);
3136 void debug_all_asserts (void);
3138 /* Dump all the registered assertions for NAME to FILE. */
3141 dump_asserts_for (FILE *file, tree name)
3145 fprintf (file, "Assertions to be inserted for ");
3146 print_generic_expr (file, name, 0);
3147 fprintf (file, "\n");
3149 loc = asserts_for[SSA_NAME_VERSION (name)];
3152 fprintf (file, "\t");
3153 print_generic_expr (file, bsi_stmt (loc->si), 0);
3154 fprintf (file, "\n\tBB #%d", loc->bb->index);
3157 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
3158 loc->e->dest->index);
3159 dump_edge_info (file, loc->e, 0);
3161 fprintf (file, "\n\tPREDICATE: ");
3162 print_generic_expr (file, name, 0);
3163 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
3164 print_generic_expr (file, loc->val, 0);
3165 fprintf (file, "\n\n");
3169 fprintf (file, "\n");
3173 /* Dump all the registered assertions for NAME to stderr. */
3176 debug_asserts_for (tree name)
3178 dump_asserts_for (stderr, name);
3182 /* Dump all the registered assertions for all the names to FILE. */
3185 dump_all_asserts (FILE *file)
3190 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
3191 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3192 dump_asserts_for (file, ssa_name (i));
3193 fprintf (file, "\n");
3197 /* Dump all the registered assertions for all the names to stderr. */
3200 debug_all_asserts (void)
3202 dump_all_asserts (stderr);
3206 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
3207 'NAME COMP_CODE VAL' at a location that dominates block BB or
3208 E->DEST, then register this location as a possible insertion point
3209 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
3211 BB, E and SI provide the exact insertion point for the new
3212 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
3213 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
3214 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
3215 must not be NULL. */
3218 register_new_assert_for (tree name,
3219 enum tree_code comp_code,
3223 block_stmt_iterator si)
3225 assert_locus_t n, loc, last_loc;
3227 basic_block dest_bb;
3229 #if defined ENABLE_CHECKING
3230 gcc_assert (bb == NULL || e == NULL);
3233 gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR
3234 && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR);
3237 /* The new assertion A will be inserted at BB or E. We need to
3238 determine if the new location is dominated by a previously
3239 registered location for A. If we are doing an edge insertion,
3240 assume that A will be inserted at E->DEST. Note that this is not
3243 If E is a critical edge, it will be split. But even if E is
3244 split, the new block will dominate the same set of blocks that
3247 The reverse, however, is not true, blocks dominated by E->DEST
3248 will not be dominated by the new block created to split E. So,
3249 if the insertion location is on a critical edge, we will not use
3250 the new location to move another assertion previously registered
3251 at a block dominated by E->DEST. */
3252 dest_bb = (bb) ? bb : e->dest;
3254 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
3255 VAL at a block dominating DEST_BB, then we don't need to insert a new
3256 one. Similarly, if the same assertion already exists at a block
3257 dominated by DEST_BB and the new location is not on a critical
3258 edge, then update the existing location for the assertion (i.e.,
3259 move the assertion up in the dominance tree).
3261 Note, this is implemented as a simple linked list because there
3262 should not be more than a handful of assertions registered per
3263 name. If this becomes a performance problem, a table hashed by
3264 COMP_CODE and VAL could be implemented. */
3265 loc = asserts_for[SSA_NAME_VERSION (name)];
3270 if (loc->comp_code == comp_code
3272 || operand_equal_p (loc->val, val, 0)))
3274 /* If the assertion NAME COMP_CODE VAL has already been
3275 registered at a basic block that dominates DEST_BB, then
3276 we don't need to insert the same assertion again. Note
3277 that we don't check strict dominance here to avoid
3278 replicating the same assertion inside the same basic
3279 block more than once (e.g., when a pointer is
3280 dereferenced several times inside a block).
3282 An exception to this rule are edge insertions. If the
3283 new assertion is to be inserted on edge E, then it will
3284 dominate all the other insertions that we may want to
3285 insert in DEST_BB. So, if we are doing an edge
3286 insertion, don't do this dominance check. */
3288 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
3291 /* Otherwise, if E is not a critical edge and DEST_BB
3292 dominates the existing location for the assertion, move
3293 the assertion up in the dominance tree by updating its
3294 location information. */
3295 if ((e == NULL || !EDGE_CRITICAL_P (e))
3296 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
3305 /* Update the last node of the list and move to the next one. */
3310 /* If we didn't find an assertion already registered for
3311 NAME COMP_CODE VAL, add a new one at the end of the list of
3312 assertions associated with NAME. */
3313 n = XNEW (struct assert_locus_d);
3317 n->comp_code = comp_code;
3324 asserts_for[SSA_NAME_VERSION (name)] = n;
3326 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
3329 /* COND is a predicate which uses NAME. Extract a suitable test code
3330 and value and store them into *CODE_P and *VAL_P so the predicate
3331 is normalized to NAME *CODE_P *VAL_P.
3333 If no extraction was possible, return FALSE, otherwise return TRUE.
3335 If INVERT is true, then we invert the result stored into *CODE_P. */
3338 extract_code_and_val_from_cond (tree name, tree cond, bool invert,
3339 enum tree_code *code_p, tree *val_p)
3341 enum tree_code comp_code;
3344 /* Predicates may be a single SSA name or NAME OP VAL. */
3347 /* If the predicate is a name, it must be NAME, in which
3348 case we create the predicate NAME == true or
3349 NAME == false accordingly. */
3350 comp_code = EQ_EXPR;
3351 val = invert ? boolean_false_node : boolean_true_node;
3355 /* Otherwise, we have a comparison of the form NAME COMP VAL
3356 or VAL COMP NAME. */
3357 if (name == TREE_OPERAND (cond, 1))
3359 /* If the predicate is of the form VAL COMP NAME, flip
3360 COMP around because we need to register NAME as the
3361 first operand in the predicate. */
3362 comp_code = swap_tree_comparison (TREE_CODE (cond));
3363 val = TREE_OPERAND (cond, 0);
3367 /* The comparison is of the form NAME COMP VAL, so the
3368 comparison code remains unchanged. */
3369 comp_code = TREE_CODE (cond);
3370 val = TREE_OPERAND (cond, 1);
3373 /* Invert the comparison code as necessary. */
3375 comp_code = invert_tree_comparison (comp_code, 0);
3377 /* VRP does not handle float types. */
3378 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)))
3381 /* Do not register always-false predicates.
3382 FIXME: this works around a limitation in fold() when dealing with
3383 enumerations. Given 'enum { N1, N2 } x;', fold will not
3384 fold 'if (x > N2)' to 'if (0)'. */
3385 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
3386 && INTEGRAL_TYPE_P (TREE_TYPE (val)))
3388 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
3389 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
3391 if (comp_code == GT_EXPR
3393 || compare_values (val, max) == 0))
3396 if (comp_code == LT_EXPR
3398 || compare_values (val, min) == 0))
3402 *code_p = comp_code;
3407 /* OP is an operand of a truth value expression which is known to have
3408 a particular value. Register any asserts for OP and for any
3409 operands in OP's defining statement.
3411 If CODE is EQ_EXPR, then we want to register OP is zero (false),
3412 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
3415 register_edge_assert_for_1 (tree op, enum tree_code code,
3416 edge e, block_stmt_iterator bsi)
3418 bool retval = false;
3419 tree op_def, rhs, val;
3421 /* We only care about SSA_NAMEs. */
3422 if (TREE_CODE (op) != SSA_NAME)
3425 /* We know that OP will have a zero or nonzero value. If OP is used
3426 more than once go ahead and register an assert for OP.
3428 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
3429 it will always be set for OP (because OP is used in a COND_EXPR in
3431 if (!has_single_use (op))
3433 val = build_int_cst (TREE_TYPE (op), 0);
3434 register_new_assert_for (op, code, val, NULL, e, bsi);
3438 /* Now look at how OP is set. If it's set from a comparison,
3439 a truth operation or some bit operations, then we may be able
3440 to register information about the operands of that assignment. */
3441 op_def = SSA_NAME_DEF_STMT (op);
3442 if (TREE_CODE (op_def) != GIMPLE_MODIFY_STMT)
3445 rhs = GIMPLE_STMT_OPERAND (op_def, 1);
3447 if (COMPARISON_CLASS_P (rhs))
3449 bool invert = (code == EQ_EXPR ? true : false);
3450 tree op0 = TREE_OPERAND (rhs, 0);
3451 tree op1 = TREE_OPERAND (rhs, 1);
3453 /* Conditionally register an assert for each SSA_NAME in the
3455 if (TREE_CODE (op0) == SSA_NAME
3456 && !has_single_use (op0)
3457 && extract_code_and_val_from_cond (op0, rhs,
3458 invert, &code, &val))
3460 register_new_assert_for (op0, code, val, NULL, e, bsi);
3464 /* Similarly for the second operand of the comparison. */
3465 if (TREE_CODE (op1) == SSA_NAME
3466 && !has_single_use (op1)
3467 && extract_code_and_val_from_cond (op1, rhs,
3468 invert, &code, &val))
3470 register_new_assert_for (op1, code, val, NULL, e, bsi);
3474 else if ((code == NE_EXPR
3475 && (TREE_CODE (rhs) == TRUTH_AND_EXPR
3476 || TREE_CODE (rhs) == BIT_AND_EXPR))
3478 && (TREE_CODE (rhs) == TRUTH_OR_EXPR
3479 || TREE_CODE (rhs) == BIT_IOR_EXPR)))
3481 /* Recurse on each operand. */
3482 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3484 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 1),
3487 else if (TREE_CODE (rhs) == TRUTH_NOT_EXPR)
3489 /* Recurse, flipping CODE. */
3490 code = invert_tree_comparison (code, false);
3491 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3494 else if (TREE_CODE (rhs) == SSA_NAME)
3496 /* Recurse through the copy. */
3497 retval |= register_edge_assert_for_1 (rhs, code, e, bsi);
3499 else if (TREE_CODE (rhs) == NOP_EXPR
3500 || TREE_CODE (rhs) == CONVERT_EXPR
3501 || TREE_CODE (rhs) == NON_LVALUE_EXPR)
3503 /* Recurse through the type conversion. */
3504 retval |= register_edge_assert_for_1 (TREE_OPERAND (rhs, 0),
3511 /* Try to register an edge assertion for SSA name NAME on edge E for
3512 the condition COND contributing to the conditional jump pointed to by SI.
3513 Return true if an assertion for NAME could be registered. */
3516 register_edge_assert_for (tree name, edge e, block_stmt_iterator si, tree cond)
3519 enum tree_code comp_code;
3520 bool retval = false;
3521 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
3523 /* Do not attempt to infer anything in names that flow through
3525 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
3528 if (!extract_code_and_val_from_cond (name, cond, is_else_edge,
3532 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
3533 reachable from E. */
3534 if (TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name)))
3536 register_new_assert_for (name, comp_code, val, NULL, e, si);
3540 /* If COND is effectively an equality test of an SSA_NAME against
3541 the value zero or one, then we may be able to assert values
3542 for SSA_NAMEs which flow into COND. */
3544 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
3545 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
3546 have nonzero value. */
3547 if (((comp_code == EQ_EXPR && integer_onep (val))
3548 || (comp_code == NE_EXPR && integer_zerop (val))))
3550 tree def_stmt = SSA_NAME_DEF_STMT (name);
3552 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3553 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_AND_EXPR
3554 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_AND_EXPR))
3556 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3557 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3558 retval |= register_edge_assert_for_1 (op0, NE_EXPR, e, si);
3559 retval |= register_edge_assert_for_1 (op1, NE_EXPR, e, si);
3563 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
3564 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
3566 if (((comp_code == EQ_EXPR && integer_zerop (val))
3567 || (comp_code == NE_EXPR && integer_onep (val))))
3569 tree def_stmt = SSA_NAME_DEF_STMT (name);
3571 if (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3572 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == TRUTH_OR_EXPR
3573 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) == BIT_IOR_EXPR))
3575 tree op0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3576 tree op1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 1);
3577 retval |= register_edge_assert_for_1 (op0, EQ_EXPR, e, si);
3578 retval |= register_edge_assert_for_1 (op1, EQ_EXPR, e, si);
3586 static bool find_assert_locations (basic_block bb);
3588 /* Determine whether the outgoing edges of BB should receive an
3589 ASSERT_EXPR for each of the operands of BB's LAST statement.
3590 The last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
3592 If any of the sub-graphs rooted at BB have an interesting use of
3593 the predicate operands, an assert location node is added to the
3594 list of assertions for the corresponding operands. */
3597 find_conditional_asserts (basic_block bb, tree last)
3600 block_stmt_iterator bsi;
3606 need_assert = false;
3607 bsi = bsi_for_stmt (last);
3609 /* Look for uses of the operands in each of the sub-graphs
3610 rooted at BB. We need to check each of the outgoing edges
3611 separately, so that we know what kind of ASSERT_EXPR to
3613 FOR_EACH_EDGE (e, ei, bb->succs)
3618 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
3619 Otherwise, when we finish traversing each of the sub-graphs, we
3620 won't know whether the variables were found in the sub-graphs or
3621 if they had been found in a block upstream from BB.
3623 This is actually a bad idea is some cases, particularly jump
3624 threading. Consider a CFG like the following:
3634 Assume that one or more operands in the conditional at the
3635 end of block 0 are used in a conditional in block 2, but not
3636 anywhere in block 1. In this case we will not insert any
3637 assert statements in block 1, which may cause us to miss
3638 opportunities to optimize, particularly for jump threading. */
3639 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3640 RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3642 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3643 to determine if any of the operands in the conditional
3644 predicate are used. */
3646 need_assert |= find_assert_locations (e->dest);
3648 /* Register the necessary assertions for each operand in the
3649 conditional predicate. */
3650 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3651 need_assert |= register_edge_assert_for (op, e, bsi,
3652 COND_EXPR_COND (last));
3655 /* Finally, indicate that we have found the operands in the
3657 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
3658 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3664 /* Traverse all the statements in block BB looking for statements that
3665 may generate useful assertions for the SSA names in their operand.
3666 If a statement produces a useful assertion A for name N_i, then the
3667 list of assertions already generated for N_i is scanned to
3668 determine if A is actually needed.
3670 If N_i already had the assertion A at a location dominating the
3671 current location, then nothing needs to be done. Otherwise, the
3672 new location for A is recorded instead.
3674 1- For every statement S in BB, all the variables used by S are
3675 added to bitmap FOUND_IN_SUBGRAPH.
3677 2- If statement S uses an operand N in a way that exposes a known
3678 value range for N, then if N was not already generated by an
3679 ASSERT_EXPR, create a new assert location for N. For instance,
3680 if N is a pointer and the statement dereferences it, we can
3681 assume that N is not NULL.
3683 3- COND_EXPRs are a special case of #2. We can derive range
3684 information from the predicate but need to insert different
3685 ASSERT_EXPRs for each of the sub-graphs rooted at the
3686 conditional block. If the last statement of BB is a conditional
3687 expression of the form 'X op Y', then
3689 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
3691 b) If the conditional is the only entry point to the sub-graph
3692 corresponding to the THEN_CLAUSE, recurse into it. On
3693 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
3694 an ASSERT_EXPR is added for the corresponding variable.
3696 c) Repeat step (b) on the ELSE_CLAUSE.
3698 d) Mark X and Y in FOUND_IN_SUBGRAPH.
3707 In this case, an assertion on the THEN clause is useful to
3708 determine that 'a' is always 9 on that edge. However, an assertion
3709 on the ELSE clause would be unnecessary.
3711 4- If BB does not end in a conditional expression, then we recurse
3712 into BB's dominator children.
3714 At the end of the recursive traversal, every SSA name will have a
3715 list of locations where ASSERT_EXPRs should be added. When a new
3716 location for name N is found, it is registered by calling
3717 register_new_assert_for. That function keeps track of all the
3718 registered assertions to prevent adding unnecessary assertions.
3719 For instance, if a pointer P_4 is dereferenced more than once in a
3720 dominator tree, only the location dominating all the dereference of
3721 P_4 will receive an ASSERT_EXPR.
3723 If this function returns true, then it means that there are names
3724 for which we need to generate ASSERT_EXPRs. Those assertions are
3725 inserted by process_assert_insertions.
3727 TODO. Handle SWITCH_EXPR. */
3730 find_assert_locations (basic_block bb)
3732 block_stmt_iterator si;
3737 if (TEST_BIT (blocks_visited, bb->index))
3740 SET_BIT (blocks_visited, bb->index);
3742 need_assert = false;
3744 /* Traverse all PHI nodes in BB marking used operands. */
3745 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3747 use_operand_p arg_p;
3750 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
3752 tree arg = USE_FROM_PTR (arg_p);
3753 if (TREE_CODE (arg) == SSA_NAME)
3755 gcc_assert (is_gimple_reg (PHI_RESULT (phi)));
3756 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg));
3761 /* Traverse all the statements in BB marking used names and looking
3762 for statements that may infer assertions for their used operands. */
3764 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
3769 stmt = bsi_stmt (si);
3771 /* See if we can derive an assertion for any of STMT's operands. */
3772 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
3775 enum tree_code comp_code;
3777 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
3778 the sub-graph of a conditional block, when we return from
3779 this recursive walk, our parent will use the
3780 FOUND_IN_SUBGRAPH bitset to determine if one of the
3781 operands it was looking for was present in the sub-graph. */
3782 SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op));
3784 /* If OP is used in such a way that we can infer a value
3785 range for it, and we don't find a previous assertion for
3786 it, create a new assertion location node for OP. */
3787 if (infer_value_range (stmt, op, &comp_code, &value))
3789 /* If we are able to infer a nonzero value range for OP,
3790 then walk backwards through the use-def chain to see if OP
3791 was set via a typecast.
3793 If so, then we can also infer a nonzero value range
3794 for the operand of the NOP_EXPR. */
3795 if (comp_code == NE_EXPR && integer_zerop (value))
3798 tree def_stmt = SSA_NAME_DEF_STMT (t);
3800 while (TREE_CODE (def_stmt) == GIMPLE_MODIFY_STMT
3802 (GIMPLE_STMT_OPERAND (def_stmt, 1)) == NOP_EXPR
3804 (TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1),
3807 (TREE_TYPE (TREE_OPERAND
3808 (GIMPLE_STMT_OPERAND (def_stmt,
3811 t = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
3812 def_stmt = SSA_NAME_DEF_STMT (t);
3814 /* Note we want to register the assert for the
3815 operand of the NOP_EXPR after SI, not after the
3817 if (! has_single_use (t))
3819 register_new_assert_for (t, comp_code, value,
3826 /* If OP is used only once, namely in this STMT, don't
3827 bother creating an ASSERT_EXPR for it. Such an
3828 ASSERT_EXPR would do nothing but increase compile time. */
3829 if (!has_single_use (op))
3831 register_new_assert_for (op, comp_code, value, bb, NULL, si);
3837 /* Remember the last statement of the block. */
3841 /* If BB's last statement is a conditional expression
3842 involving integer operands, recurse into each of the sub-graphs
3843 rooted at BB to determine if we need to add ASSERT_EXPRs. */
3845 && TREE_CODE (last) == COND_EXPR
3846 && !fp_predicate (COND_EXPR_COND (last))
3847 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
3848 need_assert |= find_conditional_asserts (bb, last);
3850 /* Recurse into the dominator children of BB. */
3851 for (son = first_dom_son (CDI_DOMINATORS, bb);
3853 son = next_dom_son (CDI_DOMINATORS, son))
3854 need_assert |= find_assert_locations (son);
3860 /* Create an ASSERT_EXPR for NAME and insert it in the location
3861 indicated by LOC. Return true if we made any edge insertions. */
3864 process_assert_insertions_for (tree name, assert_locus_t loc)
3866 /* Build the comparison expression NAME_i COMP_CODE VAL. */
3867 tree stmt, cond, assert_expr;
3871 cond = build2 (loc->comp_code, boolean_type_node, name, loc->val);
3872 assert_expr = build_assert_expr_for (cond, name);
3876 /* We have been asked to insert the assertion on an edge. This
3877 is used only by COND_EXPR and SWITCH_EXPR assertions. */
3878 #if defined ENABLE_CHECKING
3879 gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR
3880 || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR);
3883 bsi_insert_on_edge (loc->e, assert_expr);
3887 /* Otherwise, we can insert right after LOC->SI iff the
3888 statement must not be the last statement in the block. */
3889 stmt = bsi_stmt (loc->si);
3890 if (!stmt_ends_bb_p (stmt))
3892 bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT);
3896 /* If STMT must be the last statement in BB, we can only insert new
3897 assertions on the non-abnormal edge out of BB. Note that since
3898 STMT is not control flow, there may only be one non-abnormal edge
3900 FOR_EACH_EDGE (e, ei, loc->bb->succs)
3901 if (!(e->flags & EDGE_ABNORMAL))
3903 bsi_insert_on_edge (e, assert_expr);
3911 /* Process all the insertions registered for every name N_i registered
3912 in NEED_ASSERT_FOR. The list of assertions to be inserted are
3913 found in ASSERTS_FOR[i]. */
3916 process_assert_insertions (void)
3920 bool update_edges_p = false;
3921 int num_asserts = 0;
3923 if (dump_file && (dump_flags & TDF_DETAILS))
3924 dump_all_asserts (dump_file);
3926 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3928 assert_locus_t loc = asserts_for[i];
3933 assert_locus_t next = loc->next;
3934 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
3942 bsi_commit_edge_inserts ();
3944 if (dump_file && (dump_flags & TDF_STATS))
3945 fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
3950 /* Traverse the flowgraph looking for conditional jumps to insert range
3951 expressions. These range expressions are meant to provide information
3952 to optimizations that need to reason in terms of value ranges. They
3953 will not be expanded into RTL. For instance, given:
3962 this pass will transform the code into:
3968 x = ASSERT_EXPR <x, x < y>
3973 y = ASSERT_EXPR <y, x <= y>
3977 The idea is that once copy and constant propagation have run, other
3978 optimizations will be able to determine what ranges of values can 'x'
3979 take in different paths of the code, simply by checking the reaching
3980 definition of 'x'. */
3983 insert_range_assertions (void)
3989 found_in_subgraph = sbitmap_alloc (num_ssa_names);
3990 sbitmap_zero (found_in_subgraph);
3992 blocks_visited = sbitmap_alloc (last_basic_block);
3993 sbitmap_zero (blocks_visited);
3995 need_assert_for = BITMAP_ALLOC (NULL);
3996 asserts_for = XCNEWVEC (assert_locus_t, num_ssa_names);
3998 calculate_dominance_info (CDI_DOMINATORS);
4000 update_ssa_p = false;
4001 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
4002 if (find_assert_locations (e->dest))
4003 update_ssa_p = true;
4007 process_assert_insertions ();
4008 update_ssa (TODO_update_ssa_no_phi);
4011 if (dump_file && (dump_flags & TDF_DETAILS))
4013 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
4014 dump_function_to_file (current_function_decl, dump_file, dump_flags);
4017 sbitmap_free (found_in_subgraph);
4019 BITMAP_FREE (need_assert_for);
4022 /* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays
4023 and "struct" hacks. If VRP can determine that the
4024 array subscript is a constant, check if it is outside valid
4025 range. If the array subscript is a RANGE, warn if it is
4026 non-overlapping with valid range.
4027 IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */
4030 check_array_ref (tree ref, location_t* locus, bool ignore_off_by_one)
4032 value_range_t* vr = NULL;
4033 tree low_sub, up_sub;
4034 tree low_bound, up_bound = array_ref_up_bound (ref);
4036 low_sub = up_sub = TREE_OPERAND (ref, 1);
4038 if (!up_bound || !locus || TREE_NO_WARNING (ref)
4039 || TREE_CODE (up_bound) != INTEGER_CST
4040 /* Can not check flexible arrays. */
4041 || (TYPE_SIZE (TREE_TYPE (ref)) == NULL_TREE
4042 && TYPE_DOMAIN (TREE_TYPE (ref)) != NULL_TREE
4043 && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (ref))) == NULL_TREE)
4044 /* Accesses after the end of arrays of size 0 (gcc
4045 extension) and 1 are likely intentional ("struct
4047 || compare_tree_int (up_bound, 1) <= 0)
4050 low_bound = array_ref_low_bound (ref);
4052 if (TREE_CODE (low_sub) == SSA_NAME)
4054 vr = get_value_range (low_sub);
4055 if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
4057 low_sub = vr->type == VR_RANGE ? vr->max : vr->min;
4058 up_sub = vr->type == VR_RANGE ? vr->min : vr->max;
4062 if (vr && vr->type == VR_ANTI_RANGE)
4064 if (TREE_CODE (up_sub) == INTEGER_CST
4065 && tree_int_cst_lt (up_bound, up_sub)
4066 && TREE_CODE (low_sub) == INTEGER_CST
4067 && tree_int_cst_lt (low_sub, low_bound))
4069 warning (OPT_Warray_bounds,
4070 "%Harray subscript is outside array bounds", locus);
4071 TREE_NO_WARNING (ref) = 1;
4074 else if (TREE_CODE (up_sub) == INTEGER_CST
4075 && tree_int_cst_lt (up_bound, up_sub)
4076 && !tree_int_cst_equal (up_bound, up_sub)
4077 && (!ignore_off_by_one
4078 || !tree_int_cst_equal (int_const_binop (PLUS_EXPR,
4084 warning (OPT_Warray_bounds, "%Harray subscript is above array bounds",
4086 TREE_NO_WARNING (ref) = 1;
4088 else if (TREE_CODE (low_sub) == INTEGER_CST
4089 && tree_int_cst_lt (low_sub, low_bound))
4091 warning (OPT_Warray_bounds, "%Harray subscript is below array bounds",
4093 TREE_NO_WARNING (ref) = 1;
4097 /* walk_tree() callback that checks if *TP is
4098 an ARRAY_REF inside an ADDR_EXPR (in which an array
4099 subscript one outside the valid range is allowed). Call
4100 check_array_ref for each ARRAY_REF found. The location is
4104 check_array_bounds (tree *tp, int *walk_subtree, void *data)
4107 tree stmt = (tree)data;
4108 location_t *location = EXPR_LOCUS (stmt);
4110 *walk_subtree = TRUE;
4112 if (TREE_CODE (t) == ARRAY_REF)
4113 check_array_ref (t, location, false /*ignore_off_by_one*/);
4114 else if (TREE_CODE (t) == ADDR_EXPR)
4118 t = TREE_OPERAND (t, 0);
4120 /* Don't warn on statements like
4122 ssa_name = 500 + &array[-200]
4126 ssa_name = &array[-200]
4127 other_name = ssa_name + 300;
4130 produced by other optimizing passes. */
4132 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
4133 && BINARY_CLASS_P (GIMPLE_STMT_OPERAND (stmt, 1)))
4134 *walk_subtree = FALSE;
4136 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
4137 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 0)) == SSA_NAME
4138 && single_imm_use (GIMPLE_STMT_OPERAND (stmt, 0), &op, &use_stmt)
4139 && TREE_CODE (use_stmt) == GIMPLE_MODIFY_STMT
4140 && BINARY_CLASS_P (GIMPLE_STMT_OPERAND (use_stmt, 1)))
4141 *walk_subtree = FALSE;
4143 while (*walk_subtree && handled_component_p (t))
4145 if (TREE_CODE (t) == ARRAY_REF)
4146 check_array_ref (t, location, true /*ignore_off_by_one*/);
4147 t = TREE_OPERAND (t, 0);
4149 *walk_subtree = FALSE;
4155 /* Walk over all statements of all reachable BBs and call check_array_bounds
4159 check_all_array_refs (void)
4162 block_stmt_iterator si;
4166 /* Skip bb's that are clearly unreachable. */
4167 if (single_pred_p (bb))
4169 basic_block pred_bb = EDGE_PRED (bb, 0)->src;
4170 tree ls = NULL_TREE;
4172 if (!bsi_end_p (bsi_last (pred_bb)))
4173 ls = bsi_stmt (bsi_last (pred_bb));
4175 if (ls && TREE_CODE (ls) == COND_EXPR
4176 && ((COND_EXPR_COND (ls) == boolean_false_node
4177 && (EDGE_PRED (bb, 0)->flags & EDGE_TRUE_VALUE))
4178 || (COND_EXPR_COND (ls) == boolean_true_node
4179 && (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE))))
4182 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
4183 walk_tree (bsi_stmt_ptr (si), check_array_bounds,
4184 bsi_stmt (si), NULL);
4188 /* Convert range assertion expressions into the implied copies and
4189 copy propagate away the copies. Doing the trivial copy propagation
4190 here avoids the need to run the full copy propagation pass after
4193 FIXME, this will eventually lead to copy propagation removing the
4194 names that had useful range information attached to them. For
4195 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
4196 then N_i will have the range [3, +INF].
4198 However, by converting the assertion into the implied copy
4199 operation N_i = N_j, we will then copy-propagate N_j into the uses
4200 of N_i and lose the range information. We may want to hold on to
4201 ASSERT_EXPRs a little while longer as the ranges could be used in
4202 things like jump threading.
4204 The problem with keeping ASSERT_EXPRs around is that passes after
4205 VRP need to handle them appropriately.
4207 Another approach would be to make the range information a first
4208 class property of the SSA_NAME so that it can be queried from
4209 any pass. This is made somewhat more complex by the need for
4210 multiple ranges to be associated with one SSA_NAME. */
4213 remove_range_assertions (void)
4216 block_stmt_iterator si;
4218 /* Note that the BSI iterator bump happens at the bottom of the
4219 loop and no bump is necessary if we're removing the statement
4220 referenced by the current BSI. */
4222 for (si = bsi_start (bb); !bsi_end_p (si);)
4224 tree stmt = bsi_stmt (si);
4227 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
4228 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ASSERT_EXPR)
4230 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1), var;
4231 tree cond = fold (ASSERT_EXPR_COND (rhs));
4232 use_operand_p use_p;
4233 imm_use_iterator iter;
4235 gcc_assert (cond != boolean_false_node);
4237 /* Propagate the RHS into every use of the LHS. */
4238 var = ASSERT_EXPR_VAR (rhs);
4239 FOR_EACH_IMM_USE_STMT (use_stmt, iter,
4240 GIMPLE_STMT_OPERAND (stmt, 0))
4241 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
4243 SET_USE (use_p, var);
4244 gcc_assert (TREE_CODE (var) == SSA_NAME);
4247 /* And finally, remove the copy, it is not needed. */
4248 bsi_remove (&si, true);
4249 release_defs (stmt);
4255 sbitmap_free (blocks_visited);
4259 /* Return true if STMT is interesting for VRP. */
4262 stmt_interesting_for_vrp (tree stmt)
4264 if (TREE_CODE (stmt) == PHI_NODE
4265 && is_gimple_reg (PHI_RESULT (stmt))
4266 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))
4267 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt)))))
4269 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4271 tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
4272 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4274 /* In general, assignments with virtual operands are not useful
4275 for deriving ranges, with the obvious exception of calls to
4276 builtin functions. */
4277 if (TREE_CODE (lhs) == SSA_NAME
4278 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
4279 || POINTER_TYPE_P (TREE_TYPE (lhs)))
4280 && ((TREE_CODE (rhs) == CALL_EXPR
4281 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
4282 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs), 0))
4283 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
4284 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)))
4287 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
4294 /* Initialize local data structures for VRP. */
4297 vrp_initialize (void)
4301 vr_value = XCNEWVEC (value_range_t *, num_ssa_names);
4305 block_stmt_iterator si;
4308 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4310 if (!stmt_interesting_for_vrp (phi))
4312 tree lhs = PHI_RESULT (phi);
4313 set_value_range_to_varying (get_value_range (lhs));
4314 DONT_SIMULATE_AGAIN (phi) = true;
4317 DONT_SIMULATE_AGAIN (phi) = false;
4320 for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
4322 tree stmt = bsi_stmt (si);
4324 if (!stmt_interesting_for_vrp (stmt))
4328 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
4329 set_value_range_to_varying (get_value_range (def));
4330 DONT_SIMULATE_AGAIN (stmt) = true;
4334 DONT_SIMULATE_AGAIN (stmt) = false;
4341 /* Visit assignment STMT. If it produces an interesting range, record
4342 the SSA name in *OUTPUT_P. */
4344 static enum ssa_prop_result
4345 vrp_visit_assignment (tree stmt, tree *output_p)
4350 lhs = GIMPLE_STMT_OPERAND (stmt, 0);
4351 rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4353 /* We only keep track of ranges in integral and pointer types. */
4354 if (TREE_CODE (lhs) == SSA_NAME
4355 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
4356 /* It is valid to have NULL MIN/MAX values on a type. See
4357 build_range_type. */
4358 && TYPE_MIN_VALUE (TREE_TYPE (lhs))
4359 && TYPE_MAX_VALUE (TREE_TYPE (lhs)))
4360 || POINTER_TYPE_P (TREE_TYPE (lhs))))
4363 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
4365 extract_range_from_expr (&new_vr, rhs);
4367 /* If STMT is inside a loop, we may be able to know something
4368 else about the range of LHS by examining scalar evolution
4370 if (current_loops && (l = loop_containing_stmt (stmt)))
4371 adjust_range_with_scev (&new_vr, l, stmt, lhs);
4373 if (update_value_range (lhs, &new_vr))
4377 if (dump_file && (dump_flags & TDF_DETAILS))
4379 fprintf (dump_file, "Found new range for ");
4380 print_generic_expr (dump_file, lhs, 0);
4381 fprintf (dump_file, ": ");
4382 dump_value_range (dump_file, &new_vr);
4383 fprintf (dump_file, "\n\n");
4386 if (new_vr.type == VR_VARYING)
4387 return SSA_PROP_VARYING;
4389 return SSA_PROP_INTERESTING;
4392 return SSA_PROP_NOT_INTERESTING;
4395 /* Every other statement produces no useful ranges. */
4396 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
4397 set_value_range_to_varying (get_value_range (def));
4399 return SSA_PROP_VARYING;
4403 /* Compare all the value ranges for names equivalent to VAR with VAL
4404 using comparison code COMP. Return the same value returned by
4405 compare_range_with_value, including the setting of
4406 *STRICT_OVERFLOW_P. */
4409 compare_name_with_value (enum tree_code comp, tree var, tree val,
4410 bool *strict_overflow_p)
4416 int used_strict_overflow;
4418 t = retval = NULL_TREE;
4420 /* Get the set of equivalences for VAR. */
4421 e = get_value_range (var)->equiv;
4423 /* Add VAR to its own set of equivalences so that VAR's value range
4424 is processed by this loop (otherwise, we would have to replicate
4425 the body of the loop just to check VAR's value range). */
4426 bitmap_set_bit (e, SSA_NAME_VERSION (var));
4428 /* Start at -1. Set it to 0 if we do a comparison without relying
4429 on overflow, or 1 if all comparisons rely on overflow. */
4430 used_strict_overflow = -1;
4432 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
4436 value_range_t equiv_vr = *(vr_value[i]);
4438 /* If name N_i does not have a valid range, use N_i as its own
4439 range. This allows us to compare against names that may
4440 have N_i in their ranges. */
4441 if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED)
4443 equiv_vr.type = VR_RANGE;
4444 equiv_vr.min = ssa_name (i);
4445 equiv_vr.max = ssa_name (i);
4449 t = compare_range_with_value (comp, &equiv_vr, val, &sop);
4452 /* If we get different answers from different members
4453 of the equivalence set this check must be in a dead
4454 code region. Folding it to a trap representation
4455 would be correct here. For now just return don't-know. */
4465 used_strict_overflow = 0;
4466 else if (used_strict_overflow < 0)
4467 used_strict_overflow = 1;
4471 /* Remove VAR from its own equivalence set. */
4472 bitmap_clear_bit (e, SSA_NAME_VERSION (var));
4476 if (used_strict_overflow > 0)
4477 *strict_overflow_p = true;
4481 /* We couldn't find a non-NULL value for the predicate. */
4486 /* Given a comparison code COMP and names N1 and N2, compare all the
4487 ranges equivalent to N1 against all the ranges equivalent to N2
4488 to determine the value of N1 COMP N2. Return the same value
4489 returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate
4490 whether we relied on an overflow infinity in the comparison. */
4494 compare_names (enum tree_code comp, tree n1, tree n2,
4495 bool *strict_overflow_p)
4499 bitmap_iterator bi1, bi2;
4501 int used_strict_overflow;
4503 /* Compare the ranges of every name equivalent to N1 against the
4504 ranges of every name equivalent to N2. */
4505 e1 = get_value_range (n1)->equiv;
4506 e2 = get_value_range (n2)->equiv;
4508 /* Add N1 and N2 to their own set of equivalences to avoid
4509 duplicating the body of the loop just to check N1 and N2
4511 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
4512 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
4514 /* If the equivalence sets have a common intersection, then the two
4515 names can be compared without checking their ranges. */
4516 if (bitmap_intersect_p (e1, e2))
4518 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4519 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4521 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
4523 : boolean_false_node;
4526 /* Start at -1. Set it to 0 if we do a comparison without relying
4527 on overflow, or 1 if all comparisons rely on overflow. */
4528 used_strict_overflow = -1;
4530 /* Otherwise, compare all the equivalent ranges. First, add N1 and
4531 N2 to their own set of equivalences to avoid duplicating the body
4532 of the loop just to check N1 and N2 ranges. */
4533 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
4535 value_range_t vr1 = *(vr_value[i1]);
4537 /* If the range is VARYING or UNDEFINED, use the name itself. */
4538 if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED)
4540 vr1.type = VR_RANGE;
4541 vr1.min = ssa_name (i1);
4542 vr1.max = ssa_name (i1);
4545 t = retval = NULL_TREE;
4546 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
4550 value_range_t vr2 = *(vr_value[i2]);
4552 if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED)
4554 vr2.type = VR_RANGE;
4555 vr2.min = ssa_name (i2);
4556 vr2.max = ssa_name (i2);
4559 t = compare_ranges (comp, &vr1, &vr2, &sop);
4562 /* If we get different answers from different members
4563 of the equivalence set this check must be in a dead
4564 code region. Folding it to a trap representation
4565 would be correct here. For now just return don't-know. */
4569 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4570 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4576 used_strict_overflow = 0;
4577 else if (used_strict_overflow < 0)
4578 used_strict_overflow = 1;
4584 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4585 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4586 if (used_strict_overflow > 0)
4587 *strict_overflow_p = true;
4592 /* None of the equivalent ranges are useful in computing this
4594 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
4595 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
4600 /* Given a conditional predicate COND, try to determine if COND yields
4601 true or false based on the value ranges of its operands. Return
4602 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
4603 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
4604 NULL if the conditional cannot be evaluated at compile time.
4606 If USE_EQUIV_P is true, the ranges of all the names equivalent with
4607 the operands in COND are used when trying to compute its value.
4608 This is only used during final substitution. During propagation,
4609 we only check the range of each variable and not its equivalents.
4611 Set *STRICT_OVERFLOW_P to indicate whether we relied on an overflow
4612 infinity to produce the result. */
4615 vrp_evaluate_conditional_warnv (tree cond, bool use_equiv_p,
4616 bool *strict_overflow_p)
4618 gcc_assert (TREE_CODE (cond) == SSA_NAME
4619 || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison);
4621 if (TREE_CODE (cond) == SSA_NAME)
4627 retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node,
4631 value_range_t *vr = get_value_range (cond);
4632 retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node,
4636 /* If COND has a known boolean range, return it. */
4640 /* Otherwise, if COND has a symbolic range of exactly one value,
4642 vr = get_value_range (cond);
4643 if (vr->type == VR_RANGE && vr->min == vr->max)
4648 tree op0 = TREE_OPERAND (cond, 0);
4649 tree op1 = TREE_OPERAND (cond, 1);
4651 /* We only deal with integral and pointer types. */
4652 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
4653 && !POINTER_TYPE_P (TREE_TYPE (op0)))
4658 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
4659 return compare_names (TREE_CODE (cond), op0, op1,
4661 else if (TREE_CODE (op0) == SSA_NAME)
4662 return compare_name_with_value (TREE_CODE (cond), op0, op1,
4664 else if (TREE_CODE (op1) == SSA_NAME)
4665 return (compare_name_with_value
4666 (swap_tree_comparison (TREE_CODE (cond)), op1, op0,
4667 strict_overflow_p));
4671 value_range_t *vr0, *vr1;
4673 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
4674 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
4677 return compare_ranges (TREE_CODE (cond), vr0, vr1,
4679 else if (vr0 && vr1 == NULL)
4680 return compare_range_with_value (TREE_CODE (cond), vr0, op1,
4682 else if (vr0 == NULL && vr1)
4683 return (compare_range_with_value
4684 (swap_tree_comparison (TREE_CODE (cond)), vr1, op0,
4685 strict_overflow_p));
4689 /* Anything else cannot be computed statically. */
4693 /* Given COND within STMT, try to simplify it based on value range
4694 information. Return NULL if the conditional can not be evaluated.
4695 The ranges of all the names equivalent with the operands in COND
4696 will be used when trying to compute the value. If the result is
4697 based on undefined signed overflow, issue a warning if
4701 vrp_evaluate_conditional (tree cond, tree stmt)
4707 ret = vrp_evaluate_conditional_warnv (cond, true, &sop);
4711 enum warn_strict_overflow_code wc;
4712 const char* warnmsg;
4714 if (is_gimple_min_invariant (ret))
4716 wc = WARN_STRICT_OVERFLOW_CONDITIONAL;
4717 warnmsg = G_("assuming signed overflow does not occur when "
4718 "simplifying conditional to constant");
4722 wc = WARN_STRICT_OVERFLOW_COMPARISON;
4723 warnmsg = G_("assuming signed overflow does not occur when "
4724 "simplifying conditional");
4727 if (issue_strict_overflow_warning (wc))
4731 if (!EXPR_HAS_LOCATION (stmt))
4732 locus = input_location;
4734 locus = EXPR_LOCATION (stmt);
4735 warning (OPT_Wstrict_overflow, "%H%s", &locus, warnmsg);
4743 /* Visit conditional statement STMT. If we can determine which edge
4744 will be taken out of STMT's basic block, record it in
4745 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
4746 SSA_PROP_VARYING. */
4748 static enum ssa_prop_result
4749 vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p)
4754 *taken_edge_p = NULL;
4756 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
4757 add ASSERT_EXPRs for them. */
4758 if (TREE_CODE (stmt) == SWITCH_EXPR)
4759 return SSA_PROP_VARYING;
4761 cond = COND_EXPR_COND (stmt);
4763 if (dump_file && (dump_flags & TDF_DETAILS))
4768 fprintf (dump_file, "\nVisiting conditional with predicate: ");
4769 print_generic_expr (dump_file, cond, 0);
4770 fprintf (dump_file, "\nWith known ranges\n");
4772 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
4774 fprintf (dump_file, "\t");
4775 print_generic_expr (dump_file, use, 0);
4776 fprintf (dump_file, ": ");
4777 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
4780 fprintf (dump_file, "\n");
4783 /* Compute the value of the predicate COND by checking the known
4784 ranges of each of its operands.
4786 Note that we cannot evaluate all the equivalent ranges here
4787 because those ranges may not yet be final and with the current
4788 propagation strategy, we cannot determine when the value ranges
4789 of the names in the equivalence set have changed.
4791 For instance, given the following code fragment
4795 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
4799 Assume that on the first visit to i_14, i_5 has the temporary
4800 range [8, 8] because the second argument to the PHI function is
4801 not yet executable. We derive the range ~[0, 0] for i_14 and the
4802 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
4803 the first time, since i_14 is equivalent to the range [8, 8], we
4804 determine that the predicate is always false.
4806 On the next round of propagation, i_13 is determined to be
4807 VARYING, which causes i_5 to drop down to VARYING. So, another
4808 visit to i_14 is scheduled. In this second visit, we compute the
4809 exact same range and equivalence set for i_14, namely ~[0, 0] and
4810 { i_5 }. But we did not have the previous range for i_5
4811 registered, so vrp_visit_assignment thinks that the range for
4812 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
4813 is not visited again, which stops propagation from visiting
4814 statements in the THEN clause of that if().
4816 To properly fix this we would need to keep the previous range
4817 value for the names in the equivalence set. This way we would've
4818 discovered that from one visit to the other i_5 changed from
4819 range [8, 8] to VR_VARYING.
4821 However, fixing this apparent limitation may not be worth the
4822 additional checking. Testing on several code bases (GCC, DLV,
4823 MICO, TRAMP3D and SPEC2000) showed that doing this results in
4824 4 more predicates folded in SPEC. */
4826 val = vrp_evaluate_conditional_warnv (cond, false, &sop);
4830 *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val);
4833 if (dump_file && (dump_flags & TDF_DETAILS))
4835 "\nIgnoring predicate evaluation because "
4836 "it assumes that signed overflow is undefined");
4841 if (dump_file && (dump_flags & TDF_DETAILS))
4843 fprintf (dump_file, "\nPredicate evaluates to: ");
4844 if (val == NULL_TREE)
4845 fprintf (dump_file, "DON'T KNOW\n");
4847 print_generic_stmt (dump_file, val, 0);
4850 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
4854 /* Evaluate statement STMT. If the statement produces a useful range,
4855 return SSA_PROP_INTERESTING and record the SSA name with the
4856 interesting range into *OUTPUT_P.
4858 If STMT is a conditional branch and we can determine its truth
4859 value, the taken edge is recorded in *TAKEN_EDGE_P.
4861 If STMT produces a varying value, return SSA_PROP_VARYING. */
4863 static enum ssa_prop_result
4864 vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
4870 if (dump_file && (dump_flags & TDF_DETAILS))
4872 fprintf (dump_file, "\nVisiting statement:\n");
4873 print_generic_stmt (dump_file, stmt, dump_flags);
4874 fprintf (dump_file, "\n");
4877 ann = stmt_ann (stmt);
4878 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
4880 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
4882 /* In general, assignments with virtual operands are not useful
4883 for deriving ranges, with the obvious exception of calls to
4884 builtin functions. */
4885 if ((TREE_CODE (rhs) == CALL_EXPR
4886 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
4887 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs), 0))
4888 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
4889 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
4890 return vrp_visit_assignment (stmt, output_p);
4892 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
4893 return vrp_visit_cond_stmt (stmt, taken_edge_p);
4895 /* All other statements produce nothing of interest for VRP, so mark
4896 their outputs varying and prevent further simulation. */
4897 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
4898 set_value_range_to_varying (get_value_range (def));
4900 return SSA_PROP_VARYING;
4904 /* Meet operation for value ranges. Given two value ranges VR0 and
4905 VR1, store in VR0 a range that contains both VR0 and VR1. This
4906 may not be the smallest possible such range. */
4909 vrp_meet (value_range_t *vr0, value_range_t *vr1)
4911 if (vr0->type == VR_UNDEFINED)
4913 copy_value_range (vr0, vr1);
4917 if (vr1->type == VR_UNDEFINED)
4919 /* Nothing to do. VR0 already has the resulting range. */
4923 if (vr0->type == VR_VARYING)
4925 /* Nothing to do. VR0 already has the resulting range. */
4929 if (vr1->type == VR_VARYING)
4931 set_value_range_to_varying (vr0);
4935 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
4940 /* Compute the convex hull of the ranges. The lower limit of
4941 the new range is the minimum of the two ranges. If they
4942 cannot be compared, then give up. */
4943 cmp = compare_values (vr0->min, vr1->min);
4944 if (cmp == 0 || cmp == 1)
4951 /* Similarly, the upper limit of the new range is the maximum
4952 of the two ranges. If they cannot be compared, then
4954 cmp = compare_values (vr0->max, vr1->max);
4955 if (cmp == 0 || cmp == -1)
4962 /* The resulting set of equivalences is the intersection of
4964 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4965 bitmap_and_into (vr0->equiv, vr1->equiv);
4966 else if (vr0->equiv && !vr1->equiv)
4967 bitmap_clear (vr0->equiv);
4969 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
4971 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
4973 /* Two anti-ranges meet only if their complements intersect.
4974 Only handle the case of identical ranges. */
4975 if (compare_values (vr0->min, vr1->min) == 0
4976 && compare_values (vr0->max, vr1->max) == 0
4977 && compare_values (vr0->min, vr0->max) == 0)
4979 /* The resulting set of equivalences is the intersection of
4981 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
4982 bitmap_and_into (vr0->equiv, vr1->equiv);
4983 else if (vr0->equiv && !vr1->equiv)
4984 bitmap_clear (vr0->equiv);
4989 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
4991 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
4992 only handle the case where the ranges have an empty intersection.
4993 The result of the meet operation is the anti-range. */
4994 if (!symbolic_range_p (vr0)
4995 && !symbolic_range_p (vr1)
4996 && !value_ranges_intersect_p (vr0, vr1))
4998 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
4999 set. We need to compute the intersection of the two
5000 equivalence sets. */
5001 if (vr1->type == VR_ANTI_RANGE)
5002 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
5004 /* The resulting set of equivalences is the intersection of
5006 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
5007 bitmap_and_into (vr0->equiv, vr1->equiv);
5008 else if (vr0->equiv && !vr1->equiv)
5009 bitmap_clear (vr0->equiv);
5020 /* Failed to find an efficient meet. Before giving up and setting
5021 the result to VARYING, see if we can at least derive a useful
5022 anti-range. FIXME, all this nonsense about distinguishing
5023 anti-ranges from ranges is necessary because of the odd
5024 semantics of range_includes_zero_p and friends. */
5025 if (!symbolic_range_p (vr0)
5026 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
5027 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
5028 && !symbolic_range_p (vr1)
5029 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
5030 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
5032 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
5034 /* Since this meet operation did not result from the meeting of
5035 two equivalent names, VR0 cannot have any equivalences. */
5037 bitmap_clear (vr0->equiv);
5040 set_value_range_to_varying (vr0);
5044 /* Visit all arguments for PHI node PHI that flow through executable
5045 edges. If a valid value range can be derived from all the incoming
5046 value ranges, set a new range for the LHS of PHI. */
5048 static enum ssa_prop_result
5049 vrp_visit_phi_node (tree phi)
5052 tree lhs = PHI_RESULT (phi);
5053 value_range_t *lhs_vr = get_value_range (lhs);
5054 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
5055 bool all_const = true;
5057 copy_value_range (&vr_result, lhs_vr);
5059 if (dump_file && (dump_flags & TDF_DETAILS))
5061 fprintf (dump_file, "\nVisiting PHI node: ");
5062 print_generic_expr (dump_file, phi, dump_flags);
5065 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
5067 edge e = PHI_ARG_EDGE (phi, i);
5069 if (dump_file && (dump_flags & TDF_DETAILS))
5072 "\n Argument #%d (%d -> %d %sexecutable)\n",
5073 i, e->src->index, e->dest->index,
5074 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
5077 if (e->flags & EDGE_EXECUTABLE)
5079 tree arg = PHI_ARG_DEF (phi, i);
5080 value_range_t vr_arg;
5082 if (TREE_CODE (arg) == SSA_NAME)
5084 vr_arg = *(get_value_range (arg));
5089 vr_arg.type = VR_RANGE;
5092 vr_arg.equiv = NULL;
5095 if (dump_file && (dump_flags & TDF_DETAILS))
5097 fprintf (dump_file, "\t");
5098 print_generic_expr (dump_file, arg, dump_flags);
5099 fprintf (dump_file, "\n\tValue: ");
5100 dump_value_range (dump_file, &vr_arg);
5101 fprintf (dump_file, "\n");
5104 vrp_meet (&vr_result, &vr_arg);
5106 if (vr_result.type == VR_VARYING)
5111 if (vr_result.type == VR_VARYING)
5114 /* To prevent infinite iterations in the algorithm, derive ranges
5115 when the new value is slightly bigger or smaller than the
5117 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE
5120 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
5122 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
5123 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
5125 /* If the new minimum is smaller or larger than the previous
5126 one, go all the way to -INF. In the first case, to avoid
5127 iterating millions of times to reach -INF, and in the
5128 other case to avoid infinite bouncing between different
5130 if (cmp_min > 0 || cmp_min < 0)
5132 /* If we will end up with a (-INF, +INF) range, set it
5134 if (is_positive_overflow_infinity (vr_result.max)
5136 == TYPE_MAX_VALUE (TREE_TYPE (vr_result.max))))
5139 if (!needs_overflow_infinity (TREE_TYPE (vr_result.min)))
5140 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
5141 else if (supports_overflow_infinity (TREE_TYPE (vr_result.min)))
5143 negative_overflow_infinity (TREE_TYPE (vr_result.min));
5148 /* Similarly, if the new maximum is smaller or larger than
5149 the previous one, go all the way to +INF. */
5150 if (cmp_max < 0 || cmp_max > 0)
5152 /* If we will end up with a (-INF, +INF) range, set it
5154 if (is_negative_overflow_infinity (vr_result.min)
5156 == TYPE_MIN_VALUE (TREE_TYPE (vr_result.min))))
5159 if (!needs_overflow_infinity (TREE_TYPE (vr_result.max)))
5160 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
5161 else if (supports_overflow_infinity (TREE_TYPE (vr_result.max)))
5163 positive_overflow_infinity (TREE_TYPE (vr_result.max));
5170 /* If the new range is different than the previous value, keep
5172 if (update_value_range (lhs, &vr_result))
5173 return SSA_PROP_INTERESTING;
5175 /* Nothing changed, don't add outgoing edges. */
5176 return SSA_PROP_NOT_INTERESTING;
5178 /* No match found. Set the LHS to VARYING. */
5180 set_value_range_to_varying (lhs_vr);
5181 return SSA_PROP_VARYING;
5184 /* Simplify a division or modulo operator to a right shift or
5185 bitwise and if the first operand is unsigned or is greater
5186 than zero and the second operand is an exact power of two. */
5189 simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code)
5192 tree op = TREE_OPERAND (rhs, 0);
5193 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
5195 if (TYPE_UNSIGNED (TREE_TYPE (op)))
5197 val = integer_one_node;
5203 val = compare_range_with_value (GT_EXPR, vr, integer_zero_node, &sop);
5207 && integer_onep (val)
5208 && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
5212 if (!EXPR_HAS_LOCATION (stmt))
5213 locus = input_location;
5215 locus = EXPR_LOCATION (stmt);
5216 warning (OPT_Wstrict_overflow,
5217 ("%Hassuming signed overflow does not occur when "
5218 "simplifying / or %% to >> or &"),
5223 if (val && integer_onep (val))
5226 tree op0 = TREE_OPERAND (rhs, 0);
5227 tree op1 = TREE_OPERAND (rhs, 1);
5229 if (rhs_code == TRUNC_DIV_EXPR)
5231 t = build_int_cst (NULL_TREE, tree_log2 (op1));
5232 t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t);
5236 t = build_int_cst (TREE_TYPE (op1), 1);
5237 t = int_const_binop (MINUS_EXPR, op1, t, 0);
5238 t = fold_convert (TREE_TYPE (op0), t);
5239 t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t);
5242 GIMPLE_STMT_OPERAND (stmt, 1) = t;
5247 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
5248 ABS_EXPR. If the operand is <= 0, then simplify the
5249 ABS_EXPR into a NEGATE_EXPR. */
5252 simplify_abs_using_ranges (tree stmt, tree rhs)
5255 tree op = TREE_OPERAND (rhs, 0);
5256 tree type = TREE_TYPE (op);
5257 value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0));
5259 if (TYPE_UNSIGNED (type))
5261 val = integer_zero_node;
5267 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node, &sop);
5271 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node,
5276 if (integer_zerop (val))
5277 val = integer_one_node;
5278 else if (integer_onep (val))
5279 val = integer_zero_node;
5284 && (integer_onep (val) || integer_zerop (val)))
5288 if (sop && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
5292 if (!EXPR_HAS_LOCATION (stmt))
5293 locus = input_location;
5295 locus = EXPR_LOCATION (stmt);
5296 warning (OPT_Wstrict_overflow,
5297 ("%Hassuming signed overflow does not occur when "
5298 "simplifying abs (X) to X or -X"),
5302 if (integer_onep (val))
5303 t = build1 (NEGATE_EXPR, TREE_TYPE (op), op);
5307 GIMPLE_STMT_OPERAND (stmt, 1) = t;
5313 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
5314 a known value range VR.
5316 If there is one and only one value which will satisfy the
5317 conditional, then return that value. Else return NULL. */
5320 test_for_singularity (enum tree_code cond_code, tree op0,
5321 tree op1, value_range_t *vr)
5326 /* Extract minimum/maximum values which satisfy the
5327 the conditional as it was written. */
5328 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
5330 /* This should not be negative infinity; there is no overflow
5332 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
5335 if (cond_code == LT_EXPR && !is_overflow_infinity (max))
5337 tree one = build_int_cst (TREE_TYPE (op0), 1);
5338 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
5341 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
5343 /* This should not be positive infinity; there is no overflow
5345 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
5348 if (cond_code == GT_EXPR && !is_overflow_infinity (min))
5350 tree one = build_int_cst (TREE_TYPE (op0), 1);
5351 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
5355 /* Now refine the minimum and maximum values using any
5356 value range information we have for op0. */
5359 if (compare_values (vr->min, min) == -1)
5363 if (compare_values (vr->max, max) == 1)
5368 /* If the new min/max values have converged to a single value,
5369 then there is only one value which can satisfy the condition,
5370 return that value. */
5371 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
5377 /* Simplify a conditional using a relational operator to an equality
5378 test if the range information indicates only one value can satisfy
5379 the original conditional. */
5382 simplify_cond_using_ranges (tree stmt)
5384 tree cond = COND_EXPR_COND (stmt);
5385 tree op0 = TREE_OPERAND (cond, 0);
5386 tree op1 = TREE_OPERAND (cond, 1);
5387 enum tree_code cond_code = TREE_CODE (cond);
5389 if (cond_code != NE_EXPR
5390 && cond_code != EQ_EXPR
5391 && TREE_CODE (op0) == SSA_NAME
5392 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
5393 && is_gimple_min_invariant (op1))
5395 value_range_t *vr = get_value_range (op0);
5397 /* If we have range information for OP0, then we might be
5398 able to simplify this conditional. */
5399 if (vr->type == VR_RANGE)
5401 tree new = test_for_singularity (cond_code, op0, op1, vr);
5407 fprintf (dump_file, "Simplified relational ");
5408 print_generic_expr (dump_file, cond, 0);
5409 fprintf (dump_file, " into ");
5412 COND_EXPR_COND (stmt)
5413 = build2 (EQ_EXPR, boolean_type_node, op0, new);
5418 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
5419 fprintf (dump_file, "\n");
5425 /* Try again after inverting the condition. We only deal
5426 with integral types here, so no need to worry about
5427 issues with inverting FP comparisons. */
5428 cond_code = invert_tree_comparison (cond_code, false);
5429 new = test_for_singularity (cond_code, op0, op1, vr);
5435 fprintf (dump_file, "Simplified relational ");
5436 print_generic_expr (dump_file, cond, 0);
5437 fprintf (dump_file, " into ");
5440 COND_EXPR_COND (stmt)
5441 = build2 (NE_EXPR, boolean_type_node, op0, new);
5446 print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0);
5447 fprintf (dump_file, "\n");
5456 /* Simplify STMT using ranges if possible. */
5459 simplify_stmt_using_ranges (tree stmt)
5461 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
5463 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
5464 enum tree_code rhs_code = TREE_CODE (rhs);
5466 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
5467 and BIT_AND_EXPR respectively if the first operand is greater
5468 than zero and the second operand is an exact power of two. */
5469 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
5470 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
5471 && integer_pow2p (TREE_OPERAND (rhs, 1)))
5472 simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code);
5474 /* Transform ABS (X) into X or -X as appropriate. */
5475 if (rhs_code == ABS_EXPR
5476 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
5477 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
5478 simplify_abs_using_ranges (stmt, rhs);
5480 else if (TREE_CODE (stmt) == COND_EXPR
5481 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
5483 simplify_cond_using_ranges (stmt);
5487 /* Stack of dest,src equivalency pairs that need to be restored after
5488 each attempt to thread a block's incoming edge to an outgoing edge.
5490 A NULL entry is used to mark the end of pairs which need to be
5492 static VEC(tree,heap) *stack;
5494 /* A trivial wrapper so that we can present the generic jump threading
5495 code with a simple API for simplifying statements. STMT is the
5496 statement we want to simplify, WITHIN_STMT provides the location
5497 for any overflow warnings. */
5500 simplify_stmt_for_jump_threading (tree stmt, tree within_stmt)
5502 /* We only use VRP information to simplify conditionals. This is
5503 overly conservative, but it's unclear if doing more would be
5504 worth the compile time cost. */
5505 if (TREE_CODE (stmt) != COND_EXPR)
5508 return vrp_evaluate_conditional (COND_EXPR_COND (stmt), within_stmt);
5511 /* Blocks which have more than one predecessor and more than
5512 one successor present jump threading opportunities. ie,
5513 when the block is reached from a specific predecessor, we
5514 may be able to determine which of the outgoing edges will
5515 be traversed. When this optimization applies, we are able
5516 to avoid conditionals at runtime and we may expose secondary
5517 optimization opportunities.
5519 This routine is effectively a driver for the generic jump
5520 threading code. It basically just presents the generic code
5521 with edges that may be suitable for jump threading.
5523 Unlike DOM, we do not iterate VRP if jump threading was successful.
5524 While iterating may expose new opportunities for VRP, it is expected
5525 those opportunities would be very limited and the compile time cost
5526 to expose those opportunities would be significant.
5528 As jump threading opportunities are discovered, they are registered
5529 for later realization. */
5532 identify_jump_threads (void)
5537 /* Ugh. When substituting values earlier in this pass we can
5538 wipe the dominance information. So rebuild the dominator
5539 information as we need it within the jump threading code. */
5540 calculate_dominance_info (CDI_DOMINATORS);
5542 /* We do not allow VRP information to be used for jump threading
5543 across a back edge in the CFG. Otherwise it becomes too
5544 difficult to avoid eliminating loop exit tests. Of course
5545 EDGE_DFS_BACK is not accurate at this time so we have to
5547 mark_dfs_back_edges ();
5549 /* Allocate our unwinder stack to unwind any temporary equivalences
5550 that might be recorded. */
5551 stack = VEC_alloc (tree, heap, 20);
5553 /* To avoid lots of silly node creation, we create a single
5554 conditional and just modify it in-place when attempting to
5556 dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL);
5557 dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL);
5559 /* Walk through all the blocks finding those which present a
5560 potential jump threading opportunity. We could set this up
5561 as a dominator walker and record data during the walk, but
5562 I doubt it's worth the effort for the classes of jump
5563 threading opportunities we are trying to identify at this
5564 point in compilation. */
5569 /* If the generic jump threading code does not find this block
5570 interesting, then there is nothing to do. */
5571 if (! potentially_threadable_block (bb))
5574 /* We only care about blocks ending in a COND_EXPR. While there
5575 may be some value in handling SWITCH_EXPR here, I doubt it's
5576 terribly important. */
5577 last = bsi_stmt (bsi_last (bb));
5578 if (TREE_CODE (last) != COND_EXPR)
5581 /* We're basically looking for any kind of conditional with
5582 integral type arguments. */
5583 cond = COND_EXPR_COND (last);
5584 if ((TREE_CODE (cond) == SSA_NAME
5585 && INTEGRAL_TYPE_P (TREE_TYPE (cond)))
5586 || (COMPARISON_CLASS_P (cond)
5587 && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
5588 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0)))
5589 && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME
5590 || is_gimple_min_invariant (TREE_OPERAND (cond, 1)))
5591 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1)))))
5596 /* We've got a block with multiple predecessors and multiple
5597 successors which also ends in a suitable conditional. For
5598 each predecessor, see if we can thread it to a specific
5600 FOR_EACH_EDGE (e, ei, bb->preds)
5602 /* Do not thread across back edges or abnormal edges
5604 if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
5607 thread_across_edge (dummy, e, true,
5609 simplify_stmt_for_jump_threading);
5614 /* We do not actually update the CFG or SSA graphs at this point as
5615 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
5616 handle ASSERT_EXPRs gracefully. */
5619 /* We identified all the jump threading opportunities earlier, but could
5620 not transform the CFG at that time. This routine transforms the
5621 CFG and arranges for the dominator tree to be rebuilt if necessary.
5623 Note the SSA graph update will occur during the normal TODO
5624 processing by the pass manager. */
5626 finalize_jump_threads (void)
5628 bool cfg_altered = false;
5629 cfg_altered = thread_through_all_blocks ();
5631 /* If we threaded jumps, then we need to recompute the dominance
5634 free_dominance_info (CDI_DOMINATORS);
5635 VEC_free (tree, heap, stack);
5639 /* Traverse all the blocks folding conditionals with known ranges. */
5645 prop_value_t *single_val_range;
5646 bool do_value_subst_p;
5650 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
5651 dump_all_value_ranges (dump_file);
5652 fprintf (dump_file, "\n");
5655 /* We may have ended with ranges that have exactly one value. Those
5656 values can be substituted as any other copy/const propagated
5657 value using substitute_and_fold. */
5658 single_val_range = XCNEWVEC (prop_value_t, num_ssa_names);
5660 do_value_subst_p = false;
5661 for (i = 0; i < num_ssa_names; i++)
5663 && vr_value[i]->type == VR_RANGE
5664 && vr_value[i]->min == vr_value[i]->max)
5666 single_val_range[i].value = vr_value[i]->min;
5667 do_value_subst_p = true;
5670 if (!do_value_subst_p)
5672 /* We found no single-valued ranges, don't waste time trying to
5673 do single value substitution in substitute_and_fold. */
5674 free (single_val_range);
5675 single_val_range = NULL;
5678 substitute_and_fold (single_val_range, true);
5680 if (warn_array_bounds)
5681 check_all_array_refs ();
5683 /* We must identify jump threading opportunities before we release
5684 the datastructures built by VRP. */
5685 identify_jump_threads ();
5687 /* Free allocated memory. */
5688 for (i = 0; i < num_ssa_names; i++)
5691 BITMAP_FREE (vr_value[i]->equiv);
5695 free (single_val_range);
5698 /* So that we can distinguish between VRP data being available
5699 and not available. */
5704 /* Main entry point to VRP (Value Range Propagation). This pass is
5705 loosely based on J. R. C. Patterson, ``Accurate Static Branch
5706 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
5707 Programming Language Design and Implementation, pp. 67-78, 1995.
5708 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
5710 This is essentially an SSA-CCP pass modified to deal with ranges
5711 instead of constants.
5713 While propagating ranges, we may find that two or more SSA name
5714 have equivalent, though distinct ranges. For instance,
5717 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
5719 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
5723 In the code above, pointer p_5 has range [q_2, q_2], but from the
5724 code we can also determine that p_5 cannot be NULL and, if q_2 had
5725 a non-varying range, p_5's range should also be compatible with it.
5727 These equivalences are created by two expressions: ASSERT_EXPR and
5728 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
5729 result of another assertion, then we can use the fact that p_5 and
5730 p_4 are equivalent when evaluating p_5's range.
5732 Together with value ranges, we also propagate these equivalences
5733 between names so that we can take advantage of information from
5734 multiple ranges when doing final replacement. Note that this
5735 equivalency relation is transitive but not symmetric.
5737 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
5738 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
5739 in contexts where that assertion does not hold (e.g., in line 6).
5741 TODO, the main difference between this pass and Patterson's is that
5742 we do not propagate edge probabilities. We only compute whether
5743 edges can be taken or not. That is, instead of having a spectrum
5744 of jump probabilities between 0 and 1, we only deal with 0, 1 and
5745 DON'T KNOW. In the future, it may be worthwhile to propagate
5746 probabilities to aid branch prediction. */
5751 insert_range_assertions ();
5753 loop_optimizer_init (LOOPS_NORMAL);
5758 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
5764 loop_optimizer_finalize ();
5767 /* ASSERT_EXPRs must be removed before finalizing jump threads
5768 as finalizing jump threads calls the CFG cleanup code which
5769 does not properly handle ASSERT_EXPRs. */
5770 remove_range_assertions ();
5772 /* If we exposed any new variables, go ahead and put them into
5773 SSA form now, before we handle jump threading. This simplifies
5774 interactions between rewriting of _DECL nodes into SSA form
5775 and rewriting SSA_NAME nodes into SSA form after block
5776 duplication and CFG manipulation. */
5777 update_ssa (TODO_update_ssa);
5779 finalize_jump_threads ();
5786 return flag_tree_vrp != 0;
5789 struct tree_opt_pass pass_vrp =
5792 gate_vrp, /* gate */
5793 execute_vrp, /* execute */
5796 0, /* static_pass_number */
5797 TV_TREE_VRP, /* tv_id */
5798 PROP_ssa | PROP_alias, /* properties_required */
5799 0, /* properties_provided */
5800 0, /* properties_destroyed */
5801 0, /* todo_flags_start */
5806 | TODO_update_ssa, /* todo_flags_finish */