1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005, 2006, 2007, 2008 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 3, 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 COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
28 #include "basic-block.h"
29 #include "tree-flow.h"
30 #include "tree-pass.h"
31 #include "tree-dump.h"
33 #include "diagnostic.h"
37 #include "tree-scalar-evolution.h"
38 #include "tree-ssa-propagate.h"
39 #include "tree-chrec.h"
42 /* Set of SSA names found live during the RPO traversal of the function
43 for still active basic-blocks. */
46 /* Return true if the SSA name NAME is live on the edge E. */
49 live_on_edge (edge e, tree name)
51 return (live[e->dest->index]
52 && TEST_BIT (live[e->dest->index], SSA_NAME_VERSION (name)));
55 /* Local functions. */
56 static int compare_values (tree val1, tree val2);
57 static int compare_values_warnv (tree val1, tree val2, bool *);
58 static void vrp_meet (value_range_t *, value_range_t *);
59 static tree vrp_evaluate_conditional_warnv_with_ops (enum tree_code,
60 tree, tree, bool, bool *);
62 /* Location information for ASSERT_EXPRs. Each instance of this
63 structure describes an ASSERT_EXPR for an SSA name. Since a single
64 SSA name may have more than one assertion associated with it, these
65 locations are kept in a linked list attached to the corresponding
69 /* Basic block where the assertion would be inserted. */
72 /* Some assertions need to be inserted on an edge (e.g., assertions
73 generated by COND_EXPRs). In those cases, BB will be NULL. */
76 /* Pointer to the statement that generated this assertion. */
77 gimple_stmt_iterator si;
79 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
80 enum tree_code comp_code;
82 /* Value being compared against. */
85 /* Expression to compare. */
88 /* Next node in the linked list. */
89 struct assert_locus_d *next;
92 typedef struct assert_locus_d *assert_locus_t;
94 /* If bit I is present, it means that SSA name N_i has a list of
95 assertions that should be inserted in the IL. */
96 static bitmap need_assert_for;
98 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
99 holds a list of ASSERT_LOCUS_T nodes that describe where
100 ASSERT_EXPRs for SSA name N_I should be inserted. */
101 static assert_locus_t *asserts_for;
103 /* Value range array. After propagation, VR_VALUE[I] holds the range
104 of values that SSA name N_I may take. */
105 static value_range_t **vr_value;
107 /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the
108 number of executable edges we saw the last time we visited the
110 static int *vr_phi_edge_counts;
117 static VEC (edge, heap) *to_remove_edges;
118 DEF_VEC_O(switch_update);
119 DEF_VEC_ALLOC_O(switch_update, heap);
120 static VEC (switch_update, heap) *to_update_switch_stmts;
123 /* Return the maximum value for TYPEs base type. */
126 vrp_val_max (const_tree type)
128 if (!INTEGRAL_TYPE_P (type))
131 /* For integer sub-types the values for the base type are relevant. */
132 if (TREE_TYPE (type))
133 type = TREE_TYPE (type);
135 return TYPE_MAX_VALUE (type);
138 /* Return the minimum value for TYPEs base type. */
141 vrp_val_min (const_tree type)
143 if (!INTEGRAL_TYPE_P (type))
146 /* For integer sub-types the values for the base type are relevant. */
147 if (TREE_TYPE (type))
148 type = TREE_TYPE (type);
150 return TYPE_MIN_VALUE (type);
153 /* Return whether VAL is equal to the maximum value of its type. This
154 will be true for a positive overflow infinity. We can't do a
155 simple equality comparison with TYPE_MAX_VALUE because C typedefs
156 and Ada subtypes can produce types whose TYPE_MAX_VALUE is not ==
157 to the integer constant with the same value in the type. */
160 vrp_val_is_max (const_tree val)
162 tree type_max = vrp_val_max (TREE_TYPE (val));
163 return (val == type_max
164 || (type_max != NULL_TREE
165 && operand_equal_p (val, type_max, 0)));
168 /* Return whether VAL is equal to the minimum value of its type. This
169 will be true for a negative overflow infinity. */
172 vrp_val_is_min (const_tree val)
174 tree type_min = vrp_val_min (TREE_TYPE (val));
175 return (val == type_min
176 || (type_min != NULL_TREE
177 && operand_equal_p (val, type_min, 0)));
181 /* Return whether TYPE should use an overflow infinity distinct from
182 TYPE_{MIN,MAX}_VALUE. We use an overflow infinity value to
183 represent a signed overflow during VRP computations. An infinity
184 is distinct from a half-range, which will go from some number to
185 TYPE_{MIN,MAX}_VALUE. */
188 needs_overflow_infinity (const_tree type)
190 return (INTEGRAL_TYPE_P (type)
191 && !TYPE_OVERFLOW_WRAPS (type)
192 /* Integer sub-types never overflow as they are never
193 operands of arithmetic operators. */
194 && !(TREE_TYPE (type) && TREE_TYPE (type) != type));
197 /* Return whether TYPE can support our overflow infinity
198 representation: we use the TREE_OVERFLOW flag, which only exists
199 for constants. If TYPE doesn't support this, we don't optimize
200 cases which would require signed overflow--we drop them to
204 supports_overflow_infinity (const_tree type)
206 tree min = vrp_val_min (type), max = vrp_val_max (type);
207 #ifdef ENABLE_CHECKING
208 gcc_assert (needs_overflow_infinity (type));
210 return (min != NULL_TREE
211 && CONSTANT_CLASS_P (min)
213 && CONSTANT_CLASS_P (max));
216 /* VAL is the maximum or minimum value of a type. Return a
217 corresponding overflow infinity. */
220 make_overflow_infinity (tree val)
222 #ifdef ENABLE_CHECKING
223 gcc_assert (val != NULL_TREE && CONSTANT_CLASS_P (val));
225 val = copy_node (val);
226 TREE_OVERFLOW (val) = 1;
230 /* Return a negative overflow infinity for TYPE. */
233 negative_overflow_infinity (tree type)
235 #ifdef ENABLE_CHECKING
236 gcc_assert (supports_overflow_infinity (type));
238 return make_overflow_infinity (vrp_val_min (type));
241 /* Return a positive overflow infinity for TYPE. */
244 positive_overflow_infinity (tree type)
246 #ifdef ENABLE_CHECKING
247 gcc_assert (supports_overflow_infinity (type));
249 return make_overflow_infinity (vrp_val_max (type));
252 /* Return whether VAL is a negative overflow infinity. */
255 is_negative_overflow_infinity (const_tree val)
257 return (needs_overflow_infinity (TREE_TYPE (val))
258 && CONSTANT_CLASS_P (val)
259 && TREE_OVERFLOW (val)
260 && vrp_val_is_min (val));
263 /* Return whether VAL is a positive overflow infinity. */
266 is_positive_overflow_infinity (const_tree val)
268 return (needs_overflow_infinity (TREE_TYPE (val))
269 && CONSTANT_CLASS_P (val)
270 && TREE_OVERFLOW (val)
271 && vrp_val_is_max (val));
274 /* Return whether VAL is a positive or negative overflow infinity. */
277 is_overflow_infinity (const_tree val)
279 return (needs_overflow_infinity (TREE_TYPE (val))
280 && CONSTANT_CLASS_P (val)
281 && TREE_OVERFLOW (val)
282 && (vrp_val_is_min (val) || vrp_val_is_max (val)));
285 /* Return whether STMT has a constant rhs that is_overflow_infinity. */
288 stmt_overflow_infinity (gimple stmt)
290 if (is_gimple_assign (stmt)
291 && get_gimple_rhs_class (gimple_assign_rhs_code (stmt)) ==
293 return is_overflow_infinity (gimple_assign_rhs1 (stmt));
297 /* If VAL is now an overflow infinity, return VAL. Otherwise, return
298 the same value with TREE_OVERFLOW clear. This can be used to avoid
299 confusing a regular value with an overflow value. */
302 avoid_overflow_infinity (tree val)
304 if (!is_overflow_infinity (val))
307 if (vrp_val_is_max (val))
308 return vrp_val_max (TREE_TYPE (val));
311 #ifdef ENABLE_CHECKING
312 gcc_assert (vrp_val_is_min (val));
314 return vrp_val_min (TREE_TYPE (val));
319 /* Return true if ARG is marked with the nonnull attribute in the
320 current function signature. */
323 nonnull_arg_p (const_tree arg)
325 tree t, attrs, fntype;
326 unsigned HOST_WIDE_INT arg_num;
328 gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg)));
330 /* The static chain decl is always non null. */
331 if (arg == cfun->static_chain_decl)
334 fntype = TREE_TYPE (current_function_decl);
335 attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype));
337 /* If "nonnull" wasn't specified, we know nothing about the argument. */
338 if (attrs == NULL_TREE)
341 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
342 if (TREE_VALUE (attrs) == NULL_TREE)
345 /* Get the position number for ARG in the function signature. */
346 for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl);
348 t = TREE_CHAIN (t), arg_num++)
354 gcc_assert (t == arg);
356 /* Now see if ARG_NUM is mentioned in the nonnull list. */
357 for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
359 if (compare_tree_int (TREE_VALUE (t), arg_num) == 0)
367 /* Set value range VR to VR_VARYING. */
370 set_value_range_to_varying (value_range_t *vr)
372 vr->type = VR_VARYING;
373 vr->min = vr->max = NULL_TREE;
375 bitmap_clear (vr->equiv);
379 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
382 set_value_range (value_range_t *vr, enum value_range_type t, tree min,
383 tree max, bitmap equiv)
385 #if defined ENABLE_CHECKING
386 /* Check the validity of the range. */
387 if (t == VR_RANGE || t == VR_ANTI_RANGE)
391 gcc_assert (min && max);
393 if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
394 gcc_assert (!vrp_val_is_min (min) || !vrp_val_is_max (max));
396 cmp = compare_values (min, max);
397 gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
399 if (needs_overflow_infinity (TREE_TYPE (min)))
400 gcc_assert (!is_overflow_infinity (min)
401 || !is_overflow_infinity (max));
404 if (t == VR_UNDEFINED || t == VR_VARYING)
405 gcc_assert (min == NULL_TREE && max == NULL_TREE);
407 if (t == VR_UNDEFINED || t == VR_VARYING)
408 gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
415 /* Since updating the equivalence set involves deep copying the
416 bitmaps, only do it if absolutely necessary. */
417 if (vr->equiv == NULL
419 vr->equiv = BITMAP_ALLOC (NULL);
421 if (equiv != vr->equiv)
423 if (equiv && !bitmap_empty_p (equiv))
424 bitmap_copy (vr->equiv, equiv);
426 bitmap_clear (vr->equiv);
431 /* Set value range VR to the canonical form of {T, MIN, MAX, EQUIV}.
432 This means adjusting T, MIN and MAX representing the case of a
433 wrapping range with MAX < MIN covering [MIN, type_max] U [type_min, MAX]
434 as anti-rage ~[MAX+1, MIN-1]. Likewise for wrapping anti-ranges.
435 In corner cases where MAX+1 or MIN-1 wraps this will fall back
437 This routine exists to ease canonicalization in the case where we
438 extract ranges from var + CST op limit. */
441 set_and_canonicalize_value_range (value_range_t *vr, enum value_range_type t,
442 tree min, tree max, bitmap equiv)
444 /* Nothing to canonicalize for symbolic or unknown or varying ranges. */
446 && t != VR_ANTI_RANGE)
447 || TREE_CODE (min) != INTEGER_CST
448 || TREE_CODE (max) != INTEGER_CST)
450 set_value_range (vr, t, min, max, equiv);
454 /* Wrong order for min and max, to swap them and the VR type we need
456 if (tree_int_cst_lt (max, min))
458 tree one = build_int_cst (TREE_TYPE (min), 1);
459 tree tmp = int_const_binop (PLUS_EXPR, max, one, 0);
460 max = int_const_binop (MINUS_EXPR, min, one, 0);
463 /* There's one corner case, if we had [C+1, C] before we now have
464 that again. But this represents an empty value range, so drop
465 to varying in this case. */
466 if (tree_int_cst_lt (max, min))
468 set_value_range_to_varying (vr);
472 t = t == VR_RANGE ? VR_ANTI_RANGE : VR_RANGE;
475 /* Anti-ranges that can be represented as ranges should be so. */
476 if (t == VR_ANTI_RANGE)
478 bool is_min = vrp_val_is_min (min);
479 bool is_max = vrp_val_is_max (max);
481 if (is_min && is_max)
483 /* We cannot deal with empty ranges, drop to varying. */
484 set_value_range_to_varying (vr);
488 /* As a special exception preserve non-null ranges. */
489 && !(TYPE_UNSIGNED (TREE_TYPE (min))
490 && integer_zerop (max)))
492 tree one = build_int_cst (TREE_TYPE (max), 1);
493 min = int_const_binop (PLUS_EXPR, max, one, 0);
494 max = vrp_val_max (TREE_TYPE (max));
499 tree one = build_int_cst (TREE_TYPE (min), 1);
500 max = int_const_binop (MINUS_EXPR, min, one, 0);
501 min = vrp_val_min (TREE_TYPE (min));
506 set_value_range (vr, t, min, max, equiv);
509 /* Copy value range FROM into value range TO. */
512 copy_value_range (value_range_t *to, value_range_t *from)
514 set_value_range (to, from->type, from->min, from->max, from->equiv);
517 /* Set value range VR to a single value. This function is only called
518 with values we get from statements, and exists to clear the
519 TREE_OVERFLOW flag so that we don't think we have an overflow
520 infinity when we shouldn't. */
523 set_value_range_to_value (value_range_t *vr, tree val, bitmap equiv)
525 gcc_assert (is_gimple_min_invariant (val));
526 val = avoid_overflow_infinity (val);
527 set_value_range (vr, VR_RANGE, val, val, equiv);
530 /* Set value range VR to a non-negative range of type TYPE.
531 OVERFLOW_INFINITY indicates whether to use an overflow infinity
532 rather than TYPE_MAX_VALUE; this should be true if we determine
533 that the range is nonnegative based on the assumption that signed
534 overflow does not occur. */
537 set_value_range_to_nonnegative (value_range_t *vr, tree type,
538 bool overflow_infinity)
542 if (overflow_infinity && !supports_overflow_infinity (type))
544 set_value_range_to_varying (vr);
548 zero = build_int_cst (type, 0);
549 set_value_range (vr, VR_RANGE, zero,
551 ? positive_overflow_infinity (type)
552 : TYPE_MAX_VALUE (type)),
556 /* Set value range VR to a non-NULL range of type TYPE. */
559 set_value_range_to_nonnull (value_range_t *vr, tree type)
561 tree zero = build_int_cst (type, 0);
562 set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
566 /* Set value range VR to a NULL range of type TYPE. */
569 set_value_range_to_null (value_range_t *vr, tree type)
571 set_value_range_to_value (vr, build_int_cst (type, 0), vr->equiv);
575 /* Set value range VR to a range of a truthvalue of type TYPE. */
578 set_value_range_to_truthvalue (value_range_t *vr, tree type)
580 if (TYPE_PRECISION (type) == 1)
581 set_value_range_to_varying (vr);
583 set_value_range (vr, VR_RANGE,
584 build_int_cst (type, 0), build_int_cst (type, 1),
589 /* Set value range VR to VR_UNDEFINED. */
592 set_value_range_to_undefined (value_range_t *vr)
594 vr->type = VR_UNDEFINED;
595 vr->min = vr->max = NULL_TREE;
597 bitmap_clear (vr->equiv);
601 /* Return value range information for VAR.
603 If we have no values ranges recorded (ie, VRP is not running), then
604 return NULL. Otherwise create an empty range if none existed for VAR. */
606 static value_range_t *
607 get_value_range (const_tree var)
611 unsigned ver = SSA_NAME_VERSION (var);
613 /* If we have no recorded ranges, then return NULL. */
621 /* Create a default value range. */
622 vr_value[ver] = vr = XCNEW (value_range_t);
624 /* Defer allocating the equivalence set. */
627 /* If VAR is a default definition, the variable can take any value
629 sym = SSA_NAME_VAR (var);
630 if (SSA_NAME_IS_DEFAULT_DEF (var))
632 /* Try to use the "nonnull" attribute to create ~[0, 0]
633 anti-ranges for pointers. Note that this is only valid with
634 default definitions of PARM_DECLs. */
635 if (TREE_CODE (sym) == PARM_DECL
636 && POINTER_TYPE_P (TREE_TYPE (sym))
637 && nonnull_arg_p (sym))
638 set_value_range_to_nonnull (vr, TREE_TYPE (sym));
640 set_value_range_to_varying (vr);
646 /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */
649 vrp_operand_equal_p (const_tree val1, const_tree val2)
653 if (!val1 || !val2 || !operand_equal_p (val1, val2, 0))
655 if (is_overflow_infinity (val1))
656 return is_overflow_infinity (val2);
660 /* Return true, if the bitmaps B1 and B2 are equal. */
663 vrp_bitmap_equal_p (const_bitmap b1, const_bitmap b2)
667 && bitmap_equal_p (b1, b2)));
670 /* Update the value range and equivalence set for variable VAR to
671 NEW_VR. Return true if NEW_VR is different from VAR's previous
674 NOTE: This function assumes that NEW_VR is a temporary value range
675 object created for the sole purpose of updating VAR's range. The
676 storage used by the equivalence set from NEW_VR will be freed by
677 this function. Do not call update_value_range when NEW_VR
678 is the range object associated with another SSA name. */
681 update_value_range (const_tree var, value_range_t *new_vr)
683 value_range_t *old_vr;
686 /* Update the value range, if necessary. */
687 old_vr = get_value_range (var);
688 is_new = old_vr->type != new_vr->type
689 || !vrp_operand_equal_p (old_vr->min, new_vr->min)
690 || !vrp_operand_equal_p (old_vr->max, new_vr->max)
691 || !vrp_bitmap_equal_p (old_vr->equiv, new_vr->equiv);
694 set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max,
697 BITMAP_FREE (new_vr->equiv);
703 /* Add VAR and VAR's equivalence set to EQUIV. This is the central
704 point where equivalence processing can be turned on/off. */
707 add_equivalence (bitmap *equiv, const_tree var)
709 unsigned ver = SSA_NAME_VERSION (var);
710 value_range_t *vr = vr_value[ver];
713 *equiv = BITMAP_ALLOC (NULL);
714 bitmap_set_bit (*equiv, ver);
716 bitmap_ior_into (*equiv, vr->equiv);
720 /* Return true if VR is ~[0, 0]. */
723 range_is_nonnull (value_range_t *vr)
725 return vr->type == VR_ANTI_RANGE
726 && integer_zerop (vr->min)
727 && integer_zerop (vr->max);
731 /* Return true if VR is [0, 0]. */
734 range_is_null (value_range_t *vr)
736 return vr->type == VR_RANGE
737 && integer_zerop (vr->min)
738 && integer_zerop (vr->max);
742 /* Return true if value range VR involves at least one symbol. */
745 symbolic_range_p (value_range_t *vr)
747 return (!is_gimple_min_invariant (vr->min)
748 || !is_gimple_min_invariant (vr->max));
751 /* Return true if value range VR uses an overflow infinity. */
754 overflow_infinity_range_p (value_range_t *vr)
756 return (vr->type == VR_RANGE
757 && (is_overflow_infinity (vr->min)
758 || is_overflow_infinity (vr->max)));
761 /* Return false if we can not make a valid comparison based on VR;
762 this will be the case if it uses an overflow infinity and overflow
763 is not undefined (i.e., -fno-strict-overflow is in effect).
764 Otherwise return true, and set *STRICT_OVERFLOW_P to true if VR
765 uses an overflow infinity. */
768 usable_range_p (value_range_t *vr, bool *strict_overflow_p)
770 gcc_assert (vr->type == VR_RANGE);
771 if (is_overflow_infinity (vr->min))
773 *strict_overflow_p = true;
774 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->min)))
777 if (is_overflow_infinity (vr->max))
779 *strict_overflow_p = true;
780 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->max)))
787 /* Like tree_expr_nonnegative_warnv_p, but this function uses value
788 ranges obtained so far. */
791 vrp_expr_computes_nonnegative (tree expr, bool *strict_overflow_p)
793 return (tree_expr_nonnegative_warnv_p (expr, strict_overflow_p)
794 || (TREE_CODE (expr) == SSA_NAME
795 && ssa_name_nonnegative_p (expr)));
798 /* Return true if the result of assignment STMT is know to be non-negative.
799 If the return value is based on the assumption that signed overflow is
800 undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change
801 *STRICT_OVERFLOW_P.*/
804 gimple_assign_nonnegative_warnv_p (gimple stmt, bool *strict_overflow_p)
806 enum tree_code code = gimple_assign_rhs_code (stmt);
807 switch (get_gimple_rhs_class (code))
809 case GIMPLE_UNARY_RHS:
810 return tree_unary_nonnegative_warnv_p (gimple_assign_rhs_code (stmt),
811 gimple_expr_type (stmt),
812 gimple_assign_rhs1 (stmt),
814 case GIMPLE_BINARY_RHS:
815 return tree_binary_nonnegative_warnv_p (gimple_assign_rhs_code (stmt),
816 gimple_expr_type (stmt),
817 gimple_assign_rhs1 (stmt),
818 gimple_assign_rhs2 (stmt),
820 case GIMPLE_SINGLE_RHS:
821 return tree_single_nonnegative_warnv_p (gimple_assign_rhs1 (stmt),
823 case GIMPLE_INVALID_RHS:
830 /* Return true if return value of call STMT is know to be non-negative.
831 If the return value is based on the assumption that signed overflow is
832 undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change
833 *STRICT_OVERFLOW_P.*/
836 gimple_call_nonnegative_warnv_p (gimple stmt, bool *strict_overflow_p)
838 tree arg0 = gimple_call_num_args (stmt) > 0 ?
839 gimple_call_arg (stmt, 0) : NULL_TREE;
840 tree arg1 = gimple_call_num_args (stmt) > 1 ?
841 gimple_call_arg (stmt, 1) : NULL_TREE;
843 return tree_call_nonnegative_warnv_p (gimple_expr_type (stmt),
844 gimple_call_fndecl (stmt),
850 /* Return true if STMT is know to to compute a non-negative value.
851 If the return value is based on the assumption that signed overflow is
852 undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change
853 *STRICT_OVERFLOW_P.*/
856 gimple_stmt_nonnegative_warnv_p (gimple stmt, bool *strict_overflow_p)
858 switch (gimple_code (stmt))
861 return gimple_assign_nonnegative_warnv_p (stmt, strict_overflow_p);
863 return gimple_call_nonnegative_warnv_p (stmt, strict_overflow_p);
869 /* Return true if the result of assignment STMT is know to be non-zero.
870 If the return value is based on the assumption that signed overflow is
871 undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change
872 *STRICT_OVERFLOW_P.*/
875 gimple_assign_nonzero_warnv_p (gimple stmt, bool *strict_overflow_p)
877 enum tree_code code = gimple_assign_rhs_code (stmt);
878 switch (get_gimple_rhs_class (code))
880 case GIMPLE_UNARY_RHS:
881 return tree_unary_nonzero_warnv_p (gimple_assign_rhs_code (stmt),
882 gimple_expr_type (stmt),
883 gimple_assign_rhs1 (stmt),
885 case GIMPLE_BINARY_RHS:
886 return tree_binary_nonzero_warnv_p (gimple_assign_rhs_code (stmt),
887 gimple_expr_type (stmt),
888 gimple_assign_rhs1 (stmt),
889 gimple_assign_rhs2 (stmt),
891 case GIMPLE_SINGLE_RHS:
892 return tree_single_nonzero_warnv_p (gimple_assign_rhs1 (stmt),
894 case GIMPLE_INVALID_RHS:
901 /* Return true if STMT is know to to compute a non-zero value.
902 If the return value is based on the assumption that signed overflow is
903 undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change
904 *STRICT_OVERFLOW_P.*/
907 gimple_stmt_nonzero_warnv_p (gimple stmt, bool *strict_overflow_p)
909 switch (gimple_code (stmt))
912 return gimple_assign_nonzero_warnv_p (stmt, strict_overflow_p);
914 return gimple_alloca_call_p (stmt);
920 /* Like tree_expr_nonzero_warnv_p, but this function uses value ranges
924 vrp_stmt_computes_nonzero (gimple stmt, bool *strict_overflow_p)
926 if (gimple_stmt_nonzero_warnv_p (stmt, strict_overflow_p))
929 /* If we have an expression of the form &X->a, then the expression
930 is nonnull if X is nonnull. */
931 if (is_gimple_assign (stmt)
932 && gimple_assign_rhs_code (stmt) == ADDR_EXPR)
934 tree expr = gimple_assign_rhs1 (stmt);
935 tree base = get_base_address (TREE_OPERAND (expr, 0));
937 if (base != NULL_TREE
938 && TREE_CODE (base) == INDIRECT_REF
939 && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
941 value_range_t *vr = get_value_range (TREE_OPERAND (base, 0));
942 if (range_is_nonnull (vr))
950 /* Returns true if EXPR is a valid value (as expected by compare_values) --
951 a gimple invariant, or SSA_NAME +- CST. */
954 valid_value_p (tree expr)
956 if (TREE_CODE (expr) == SSA_NAME)
959 if (TREE_CODE (expr) == PLUS_EXPR
960 || TREE_CODE (expr) == MINUS_EXPR)
961 return (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME
962 && TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST);
964 return is_gimple_min_invariant (expr);
970 -2 if those are incomparable. */
972 operand_less_p (tree val, tree val2)
974 /* LT is folded faster than GE and others. Inline the common case. */
975 if (TREE_CODE (val) == INTEGER_CST && TREE_CODE (val2) == INTEGER_CST)
977 if (TYPE_UNSIGNED (TREE_TYPE (val)))
978 return INT_CST_LT_UNSIGNED (val, val2);
981 if (INT_CST_LT (val, val2))
989 fold_defer_overflow_warnings ();
991 tcmp = fold_binary_to_constant (LT_EXPR, boolean_type_node, val, val2);
993 fold_undefer_and_ignore_overflow_warnings ();
996 || TREE_CODE (tcmp) != INTEGER_CST)
999 if (!integer_zerop (tcmp))
1003 /* val >= val2, not considering overflow infinity. */
1004 if (is_negative_overflow_infinity (val))
1005 return is_negative_overflow_infinity (val2) ? 0 : 1;
1006 else if (is_positive_overflow_infinity (val2))
1007 return is_positive_overflow_infinity (val) ? 0 : 1;
1012 /* Compare two values VAL1 and VAL2. Return
1014 -2 if VAL1 and VAL2 cannot be compared at compile-time,
1017 +1 if VAL1 > VAL2, and
1020 This is similar to tree_int_cst_compare but supports pointer values
1021 and values that cannot be compared at compile time.
1023 If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to
1024 true if the return value is only valid if we assume that signed
1025 overflow is undefined. */
1028 compare_values_warnv (tree val1, tree val2, bool *strict_overflow_p)
1033 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
1035 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
1036 == POINTER_TYPE_P (TREE_TYPE (val2)));
1037 /* Convert the two values into the same type. This is needed because
1038 sizetype causes sign extension even for unsigned types. */
1039 val2 = fold_convert (TREE_TYPE (val1), val2);
1040 STRIP_USELESS_TYPE_CONVERSION (val2);
1042 if ((TREE_CODE (val1) == SSA_NAME
1043 || TREE_CODE (val1) == PLUS_EXPR
1044 || TREE_CODE (val1) == MINUS_EXPR)
1045 && (TREE_CODE (val2) == SSA_NAME
1046 || TREE_CODE (val2) == PLUS_EXPR
1047 || TREE_CODE (val2) == MINUS_EXPR))
1049 tree n1, c1, n2, c2;
1050 enum tree_code code1, code2;
1052 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
1053 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
1054 same name, return -2. */
1055 if (TREE_CODE (val1) == SSA_NAME)
1063 code1 = TREE_CODE (val1);
1064 n1 = TREE_OPERAND (val1, 0);
1065 c1 = TREE_OPERAND (val1, 1);
1066 if (tree_int_cst_sgn (c1) == -1)
1068 if (is_negative_overflow_infinity (c1))
1070 c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1);
1073 code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
1077 if (TREE_CODE (val2) == SSA_NAME)
1085 code2 = TREE_CODE (val2);
1086 n2 = TREE_OPERAND (val2, 0);
1087 c2 = TREE_OPERAND (val2, 1);
1088 if (tree_int_cst_sgn (c2) == -1)
1090 if (is_negative_overflow_infinity (c2))
1092 c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2);
1095 code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR;
1099 /* Both values must use the same name. */
1103 if (code1 == SSA_NAME
1104 && code2 == SSA_NAME)
1108 /* If overflow is defined we cannot simplify more. */
1109 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1)))
1112 if (strict_overflow_p != NULL
1113 && (code1 == SSA_NAME || !TREE_NO_WARNING (val1))
1114 && (code2 == SSA_NAME || !TREE_NO_WARNING (val2)))
1115 *strict_overflow_p = true;
1117 if (code1 == SSA_NAME)
1119 if (code2 == PLUS_EXPR)
1120 /* NAME < NAME + CST */
1122 else if (code2 == MINUS_EXPR)
1123 /* NAME > NAME - CST */
1126 else if (code1 == PLUS_EXPR)
1128 if (code2 == SSA_NAME)
1129 /* NAME + CST > NAME */
1131 else if (code2 == PLUS_EXPR)
1132 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
1133 return compare_values_warnv (c1, c2, strict_overflow_p);
1134 else if (code2 == MINUS_EXPR)
1135 /* NAME + CST1 > NAME - CST2 */
1138 else if (code1 == MINUS_EXPR)
1140 if (code2 == SSA_NAME)
1141 /* NAME - CST < NAME */
1143 else if (code2 == PLUS_EXPR)
1144 /* NAME - CST1 < NAME + CST2 */
1146 else if (code2 == MINUS_EXPR)
1147 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
1148 C1 and C2 are swapped in the call to compare_values. */
1149 return compare_values_warnv (c2, c1, strict_overflow_p);
1155 /* We cannot compare non-constants. */
1156 if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))
1159 if (!POINTER_TYPE_P (TREE_TYPE (val1)))
1161 /* We cannot compare overflowed values, except for overflow
1163 if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
1165 if (strict_overflow_p != NULL)
1166 *strict_overflow_p = true;
1167 if (is_negative_overflow_infinity (val1))
1168 return is_negative_overflow_infinity (val2) ? 0 : -1;
1169 else if (is_negative_overflow_infinity (val2))
1171 else if (is_positive_overflow_infinity (val1))
1172 return is_positive_overflow_infinity (val2) ? 0 : 1;
1173 else if (is_positive_overflow_infinity (val2))
1178 return tree_int_cst_compare (val1, val2);
1184 /* First see if VAL1 and VAL2 are not the same. */
1185 if (val1 == val2 || operand_equal_p (val1, val2, 0))
1188 /* If VAL1 is a lower address than VAL2, return -1. */
1189 if (operand_less_p (val1, val2) == 1)
1192 /* If VAL1 is a higher address than VAL2, return +1. */
1193 if (operand_less_p (val2, val1) == 1)
1196 /* If VAL1 is different than VAL2, return +2.
1197 For integer constants we either have already returned -1 or 1
1198 or they are equivalent. We still might succeed in proving
1199 something about non-trivial operands. */
1200 if (TREE_CODE (val1) != INTEGER_CST
1201 || TREE_CODE (val2) != INTEGER_CST)
1203 t = fold_binary_to_constant (NE_EXPR, boolean_type_node, val1, val2);
1204 if (t && integer_onep (t))
1212 /* Compare values like compare_values_warnv, but treat comparisons of
1213 nonconstants which rely on undefined overflow as incomparable. */
1216 compare_values (tree val1, tree val2)
1222 ret = compare_values_warnv (val1, val2, &sop);
1224 && (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2)))
1230 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
1231 0 if VAL is not inside VR,
1232 -2 if we cannot tell either way.
1234 FIXME, the current semantics of this functions are a bit quirky
1235 when taken in the context of VRP. In here we do not care
1236 about VR's type. If VR is the anti-range ~[3, 5] the call
1237 value_inside_range (4, VR) will return 1.
1239 This is counter-intuitive in a strict sense, but the callers
1240 currently expect this. They are calling the function
1241 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
1242 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
1245 This also applies to value_ranges_intersect_p and
1246 range_includes_zero_p. The semantics of VR_RANGE and
1247 VR_ANTI_RANGE should be encoded here, but that also means
1248 adapting the users of these functions to the new semantics.
1250 Benchmark compile/20001226-1.c compilation time after changing this
1254 value_inside_range (tree val, value_range_t * vr)
1258 cmp1 = operand_less_p (val, vr->min);
1264 cmp2 = operand_less_p (vr->max, val);
1272 /* Return true if value ranges VR0 and VR1 have a non-empty
1275 Benchmark compile/20001226-1.c compilation time after changing this
1280 value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1)
1282 /* The value ranges do not intersect if the maximum of the first range is
1283 less than the minimum of the second range or vice versa.
1284 When those relations are unknown, we can't do any better. */
1285 if (operand_less_p (vr0->max, vr1->min) != 0)
1287 if (operand_less_p (vr1->max, vr0->min) != 0)
1293 /* Return true if VR includes the value zero, false otherwise. FIXME,
1294 currently this will return false for an anti-range like ~[-4, 3].
1295 This will be wrong when the semantics of value_inside_range are
1296 modified (currently the users of this function expect these
1300 range_includes_zero_p (value_range_t *vr)
1304 gcc_assert (vr->type != VR_UNDEFINED
1305 && vr->type != VR_VARYING
1306 && !symbolic_range_p (vr));
1308 zero = build_int_cst (TREE_TYPE (vr->min), 0);
1309 return (value_inside_range (zero, vr) == 1);
1312 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
1313 false otherwise or if no value range information is available. */
1316 ssa_name_nonnegative_p (const_tree t)
1318 value_range_t *vr = get_value_range (t);
1323 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
1324 which would return a useful value should be encoded as a VR_RANGE. */
1325 if (vr->type == VR_RANGE)
1327 int result = compare_values (vr->min, integer_zero_node);
1329 return (result == 0 || result == 1);
1334 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
1335 false otherwise or if no value range information is available. */
1338 ssa_name_nonzero_p (const_tree t)
1340 value_range_t *vr = get_value_range (t);
1345 /* A VR_RANGE which does not include zero is a nonzero value. */
1346 if (vr->type == VR_RANGE && !symbolic_range_p (vr))
1347 return ! range_includes_zero_p (vr);
1349 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
1350 if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr))
1351 return range_includes_zero_p (vr);
1356 /* If OP has a value range with a single constant value return that,
1357 otherwise return NULL_TREE. This returns OP itself if OP is a
1361 op_with_constant_singleton_value_range (tree op)
1365 if (is_gimple_min_invariant (op))
1368 if (TREE_CODE (op) != SSA_NAME)
1371 vr = get_value_range (op);
1372 if (vr->type == VR_RANGE
1373 && operand_equal_p (vr->min, vr->max, 0)
1374 && is_gimple_min_invariant (vr->min))
1381 /* Extract value range information from an ASSERT_EXPR EXPR and store
1385 extract_range_from_assert (value_range_t *vr_p, tree expr)
1387 tree var, cond, limit, min, max, type;
1388 value_range_t *var_vr, *limit_vr;
1389 enum tree_code cond_code;
1391 var = ASSERT_EXPR_VAR (expr);
1392 cond = ASSERT_EXPR_COND (expr);
1394 gcc_assert (COMPARISON_CLASS_P (cond));
1396 /* Find VAR in the ASSERT_EXPR conditional. */
1397 if (var == TREE_OPERAND (cond, 0)
1398 || TREE_CODE (TREE_OPERAND (cond, 0)) == PLUS_EXPR
1399 || TREE_CODE (TREE_OPERAND (cond, 0)) == NOP_EXPR)
1401 /* If the predicate is of the form VAR COMP LIMIT, then we just
1402 take LIMIT from the RHS and use the same comparison code. */
1403 cond_code = TREE_CODE (cond);
1404 limit = TREE_OPERAND (cond, 1);
1405 cond = TREE_OPERAND (cond, 0);
1409 /* If the predicate is of the form LIMIT COMP VAR, then we need
1410 to flip around the comparison code to create the proper range
1412 cond_code = swap_tree_comparison (TREE_CODE (cond));
1413 limit = TREE_OPERAND (cond, 0);
1414 cond = TREE_OPERAND (cond, 1);
1417 limit = avoid_overflow_infinity (limit);
1419 type = TREE_TYPE (limit);
1420 gcc_assert (limit != var);
1422 /* For pointer arithmetic, we only keep track of pointer equality
1424 if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
1426 set_value_range_to_varying (vr_p);
1430 /* If LIMIT is another SSA name and LIMIT has a range of its own,
1431 try to use LIMIT's range to avoid creating symbolic ranges
1433 limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
1435 /* LIMIT's range is only interesting if it has any useful information. */
1437 && (limit_vr->type == VR_UNDEFINED
1438 || limit_vr->type == VR_VARYING
1439 || symbolic_range_p (limit_vr)))
1442 /* Initially, the new range has the same set of equivalences of
1443 VAR's range. This will be revised before returning the final
1444 value. Since assertions may be chained via mutually exclusive
1445 predicates, we will need to trim the set of equivalences before
1447 gcc_assert (vr_p->equiv == NULL);
1448 add_equivalence (&vr_p->equiv, var);
1450 /* Extract a new range based on the asserted comparison for VAR and
1451 LIMIT's value range. Notice that if LIMIT has an anti-range, we
1452 will only use it for equality comparisons (EQ_EXPR). For any
1453 other kind of assertion, we cannot derive a range from LIMIT's
1454 anti-range that can be used to describe the new range. For
1455 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
1456 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
1457 no single range for x_2 that could describe LE_EXPR, so we might
1458 as well build the range [b_4, +INF] for it.
1459 One special case we handle is extracting a range from a
1460 range test encoded as (unsigned)var + CST <= limit. */
1461 if (TREE_CODE (cond) == NOP_EXPR
1462 || TREE_CODE (cond) == PLUS_EXPR)
1464 if (TREE_CODE (cond) == PLUS_EXPR)
1466 min = fold_build1 (NEGATE_EXPR, TREE_TYPE (TREE_OPERAND (cond, 1)),
1467 TREE_OPERAND (cond, 1));
1468 max = int_const_binop (PLUS_EXPR, limit, min, 0);
1469 cond = TREE_OPERAND (cond, 0);
1473 min = build_int_cst (TREE_TYPE (var), 0);
1477 /* Make sure to not set TREE_OVERFLOW on the final type
1478 conversion. We are willingly interpreting large positive
1479 unsigned values as negative singed values here. */
1480 min = force_fit_type_double (TREE_TYPE (var), TREE_INT_CST_LOW (min),
1481 TREE_INT_CST_HIGH (min), 0, false);
1482 max = force_fit_type_double (TREE_TYPE (var), TREE_INT_CST_LOW (max),
1483 TREE_INT_CST_HIGH (max), 0, false);
1485 /* We can transform a max, min range to an anti-range or
1486 vice-versa. Use set_and_canonicalize_value_range which does
1488 if (cond_code == LE_EXPR)
1489 set_and_canonicalize_value_range (vr_p, VR_RANGE,
1490 min, max, vr_p->equiv);
1491 else if (cond_code == GT_EXPR)
1492 set_and_canonicalize_value_range (vr_p, VR_ANTI_RANGE,
1493 min, max, vr_p->equiv);
1497 else if (cond_code == EQ_EXPR)
1499 enum value_range_type range_type;
1503 range_type = limit_vr->type;
1504 min = limit_vr->min;
1505 max = limit_vr->max;
1509 range_type = VR_RANGE;
1514 set_value_range (vr_p, range_type, min, max, vr_p->equiv);
1516 /* When asserting the equality VAR == LIMIT and LIMIT is another
1517 SSA name, the new range will also inherit the equivalence set
1519 if (TREE_CODE (limit) == SSA_NAME)
1520 add_equivalence (&vr_p->equiv, limit);
1522 else if (cond_code == NE_EXPR)
1524 /* As described above, when LIMIT's range is an anti-range and
1525 this assertion is an inequality (NE_EXPR), then we cannot
1526 derive anything from the anti-range. For instance, if
1527 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
1528 not imply that VAR's range is [0, 0]. So, in the case of
1529 anti-ranges, we just assert the inequality using LIMIT and
1532 If LIMIT_VR is a range, we can only use it to build a new
1533 anti-range if LIMIT_VR is a single-valued range. For
1534 instance, if LIMIT_VR is [0, 1], the predicate
1535 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
1536 Rather, it means that for value 0 VAR should be ~[0, 0]
1537 and for value 1, VAR should be ~[1, 1]. We cannot
1538 represent these ranges.
1540 The only situation in which we can build a valid
1541 anti-range is when LIMIT_VR is a single-valued range
1542 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
1543 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
1545 && limit_vr->type == VR_RANGE
1546 && compare_values (limit_vr->min, limit_vr->max) == 0)
1548 min = limit_vr->min;
1549 max = limit_vr->max;
1553 /* In any other case, we cannot use LIMIT's range to build a
1554 valid anti-range. */
1558 /* If MIN and MAX cover the whole range for their type, then
1559 just use the original LIMIT. */
1560 if (INTEGRAL_TYPE_P (type)
1561 && vrp_val_is_min (min)
1562 && vrp_val_is_max (max))
1565 set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv);
1567 else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
1569 min = TYPE_MIN_VALUE (type);
1571 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
1575 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1576 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
1578 max = limit_vr->max;
1581 /* If the maximum value forces us to be out of bounds, simply punt.
1582 It would be pointless to try and do anything more since this
1583 all should be optimized away above us. */
1584 if ((cond_code == LT_EXPR
1585 && compare_values (max, min) == 0)
1586 || is_overflow_infinity (max))
1587 set_value_range_to_varying (vr_p);
1590 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
1591 if (cond_code == LT_EXPR)
1593 tree one = build_int_cst (type, 1);
1594 max = fold_build2 (MINUS_EXPR, type, max, one);
1596 TREE_NO_WARNING (max) = 1;
1599 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1602 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
1604 max = TYPE_MAX_VALUE (type);
1606 if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE)
1610 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1611 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
1613 min = limit_vr->min;
1616 /* If the minimum value forces us to be out of bounds, simply punt.
1617 It would be pointless to try and do anything more since this
1618 all should be optimized away above us. */
1619 if ((cond_code == GT_EXPR
1620 && compare_values (min, max) == 0)
1621 || is_overflow_infinity (min))
1622 set_value_range_to_varying (vr_p);
1625 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
1626 if (cond_code == GT_EXPR)
1628 tree one = build_int_cst (type, 1);
1629 min = fold_build2 (PLUS_EXPR, type, min, one);
1631 TREE_NO_WARNING (min) = 1;
1634 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1640 /* If VAR already had a known range, it may happen that the new
1641 range we have computed and VAR's range are not compatible. For
1645 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
1647 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
1649 While the above comes from a faulty program, it will cause an ICE
1650 later because p_8 and p_6 will have incompatible ranges and at
1651 the same time will be considered equivalent. A similar situation
1655 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
1657 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
1659 Again i_6 and i_7 will have incompatible ranges. It would be
1660 pointless to try and do anything with i_7's range because
1661 anything dominated by 'if (i_5 < 5)' will be optimized away.
1662 Note, due to the wa in which simulation proceeds, the statement
1663 i_7 = ASSERT_EXPR <...> we would never be visited because the
1664 conditional 'if (i_5 < 5)' always evaluates to false. However,
1665 this extra check does not hurt and may protect against future
1666 changes to VRP that may get into a situation similar to the
1667 NULL pointer dereference example.
1669 Note that these compatibility tests are only needed when dealing
1670 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1671 are both anti-ranges, they will always be compatible, because two
1672 anti-ranges will always have a non-empty intersection. */
1674 var_vr = get_value_range (var);
1676 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1677 ranges or anti-ranges. */
1678 if (vr_p->type == VR_VARYING
1679 || vr_p->type == VR_UNDEFINED
1680 || var_vr->type == VR_VARYING
1681 || var_vr->type == VR_UNDEFINED
1682 || symbolic_range_p (vr_p)
1683 || symbolic_range_p (var_vr))
1686 if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
1688 /* If the two ranges have a non-empty intersection, we can
1689 refine the resulting range. Since the assert expression
1690 creates an equivalency and at the same time it asserts a
1691 predicate, we can take the intersection of the two ranges to
1692 get better precision. */
1693 if (value_ranges_intersect_p (var_vr, vr_p))
1695 /* Use the larger of the two minimums. */
1696 if (compare_values (vr_p->min, var_vr->min) == -1)
1701 /* Use the smaller of the two maximums. */
1702 if (compare_values (vr_p->max, var_vr->max) == 1)
1707 set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv);
1711 /* The two ranges do not intersect, set the new range to
1712 VARYING, because we will not be able to do anything
1713 meaningful with it. */
1714 set_value_range_to_varying (vr_p);
1717 else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
1718 || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
1720 /* A range and an anti-range will cancel each other only if
1721 their ends are the same. For instance, in the example above,
1722 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1723 so VR_P should be set to VR_VARYING. */
1724 if (compare_values (var_vr->min, vr_p->min) == 0
1725 && compare_values (var_vr->max, vr_p->max) == 0)
1726 set_value_range_to_varying (vr_p);
1729 tree min, max, anti_min, anti_max, real_min, real_max;
1732 /* We want to compute the logical AND of the two ranges;
1733 there are three cases to consider.
1736 1. The VR_ANTI_RANGE range is completely within the
1737 VR_RANGE and the endpoints of the ranges are
1738 different. In that case the resulting range
1739 should be whichever range is more precise.
1740 Typically that will be the VR_RANGE.
1742 2. The VR_ANTI_RANGE is completely disjoint from
1743 the VR_RANGE. In this case the resulting range
1744 should be the VR_RANGE.
1746 3. There is some overlap between the VR_ANTI_RANGE
1749 3a. If the high limit of the VR_ANTI_RANGE resides
1750 within the VR_RANGE, then the result is a new
1751 VR_RANGE starting at the high limit of the
1752 VR_ANTI_RANGE + 1 and extending to the
1753 high limit of the original VR_RANGE.
1755 3b. If the low limit of the VR_ANTI_RANGE resides
1756 within the VR_RANGE, then the result is a new
1757 VR_RANGE starting at the low limit of the original
1758 VR_RANGE and extending to the low limit of the
1759 VR_ANTI_RANGE - 1. */
1760 if (vr_p->type == VR_ANTI_RANGE)
1762 anti_min = vr_p->min;
1763 anti_max = vr_p->max;
1764 real_min = var_vr->min;
1765 real_max = var_vr->max;
1769 anti_min = var_vr->min;
1770 anti_max = var_vr->max;
1771 real_min = vr_p->min;
1772 real_max = vr_p->max;
1776 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1777 not including any endpoints. */
1778 if (compare_values (anti_max, real_max) == -1
1779 && compare_values (anti_min, real_min) == 1)
1781 /* If the range is covering the whole valid range of
1782 the type keep the anti-range. */
1783 if (!vrp_val_is_min (real_min)
1784 || !vrp_val_is_max (real_max))
1785 set_value_range (vr_p, VR_RANGE, real_min,
1786 real_max, vr_p->equiv);
1788 /* Case 2, VR_ANTI_RANGE completely disjoint from
1790 else if (compare_values (anti_min, real_max) == 1
1791 || compare_values (anti_max, real_min) == -1)
1793 set_value_range (vr_p, VR_RANGE, real_min,
1794 real_max, vr_p->equiv);
1796 /* Case 3a, the anti-range extends into the low
1797 part of the real range. Thus creating a new
1798 low for the real range. */
1799 else if (((cmp = compare_values (anti_max, real_min)) == 1
1801 && compare_values (anti_max, real_max) == -1)
1803 gcc_assert (!is_positive_overflow_infinity (anti_max));
1804 if (needs_overflow_infinity (TREE_TYPE (anti_max))
1805 && vrp_val_is_max (anti_max))
1807 if (!supports_overflow_infinity (TREE_TYPE (var_vr->min)))
1809 set_value_range_to_varying (vr_p);
1812 min = positive_overflow_infinity (TREE_TYPE (var_vr->min));
1814 else if (!POINTER_TYPE_P (TREE_TYPE (var_vr->min)))
1815 min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min),
1817 build_int_cst (TREE_TYPE (var_vr->min), 1));
1819 min = fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (var_vr->min),
1820 anti_max, size_int (1));
1822 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1824 /* Case 3b, the anti-range extends into the high
1825 part of the real range. Thus creating a new
1826 higher for the real range. */
1827 else if (compare_values (anti_min, real_min) == 1
1828 && ((cmp = compare_values (anti_min, real_max)) == -1
1831 gcc_assert (!is_negative_overflow_infinity (anti_min));
1832 if (needs_overflow_infinity (TREE_TYPE (anti_min))
1833 && vrp_val_is_min (anti_min))
1835 if (!supports_overflow_infinity (TREE_TYPE (var_vr->min)))
1837 set_value_range_to_varying (vr_p);
1840 max = negative_overflow_infinity (TREE_TYPE (var_vr->min));
1842 else if (!POINTER_TYPE_P (TREE_TYPE (var_vr->min)))
1843 max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min),
1845 build_int_cst (TREE_TYPE (var_vr->min), 1));
1847 max = fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (var_vr->min),
1851 set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv);
1858 /* Extract range information from SSA name VAR and store it in VR. If
1859 VAR has an interesting range, use it. Otherwise, create the
1860 range [VAR, VAR] and return it. This is useful in situations where
1861 we may have conditionals testing values of VARYING names. For
1868 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1872 extract_range_from_ssa_name (value_range_t *vr, tree var)
1874 value_range_t *var_vr = get_value_range (var);
1876 if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING)
1877 copy_value_range (vr, var_vr);
1879 set_value_range (vr, VR_RANGE, var, var, NULL);
1881 add_equivalence (&vr->equiv, var);
1885 /* Wrapper around int_const_binop. If the operation overflows and we
1886 are not using wrapping arithmetic, then adjust the result to be
1887 -INF or +INF depending on CODE, VAL1 and VAL2. This can return
1888 NULL_TREE if we need to use an overflow infinity representation but
1889 the type does not support it. */
1892 vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
1896 res = int_const_binop (code, val1, val2, 0);
1898 /* If we are not using wrapping arithmetic, operate symbolically
1899 on -INF and +INF. */
1900 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1)))
1902 int checkz = compare_values (res, val1);
1903 bool overflow = false;
1905 /* Ensure that res = val1 [+*] val2 >= val1
1906 or that res = val1 - val2 <= val1. */
1907 if ((code == PLUS_EXPR
1908 && !(checkz == 1 || checkz == 0))
1909 || (code == MINUS_EXPR
1910 && !(checkz == 0 || checkz == -1)))
1914 /* Checking for multiplication overflow is done by dividing the
1915 output of the multiplication by the first input of the
1916 multiplication. If the result of that division operation is
1917 not equal to the second input of the multiplication, then the
1918 multiplication overflowed. */
1919 else if (code == MULT_EXPR && !integer_zerop (val1))
1921 tree tmp = int_const_binop (TRUNC_DIV_EXPR,
1924 int check = compare_values (tmp, val2);
1932 res = copy_node (res);
1933 TREE_OVERFLOW (res) = 1;
1937 else if ((TREE_OVERFLOW (res)
1938 && !TREE_OVERFLOW (val1)
1939 && !TREE_OVERFLOW (val2))
1940 || is_overflow_infinity (val1)
1941 || is_overflow_infinity (val2))
1943 /* If the operation overflowed but neither VAL1 nor VAL2 are
1944 overflown, return -INF or +INF depending on the operation
1945 and the combination of signs of the operands. */
1946 int sgn1 = tree_int_cst_sgn (val1);
1947 int sgn2 = tree_int_cst_sgn (val2);
1949 if (needs_overflow_infinity (TREE_TYPE (res))
1950 && !supports_overflow_infinity (TREE_TYPE (res)))
1953 /* We have to punt on adding infinities of different signs,
1954 since we can't tell what the sign of the result should be.
1955 Likewise for subtracting infinities of the same sign. */
1956 if (((code == PLUS_EXPR && sgn1 != sgn2)
1957 || (code == MINUS_EXPR && sgn1 == sgn2))
1958 && is_overflow_infinity (val1)
1959 && is_overflow_infinity (val2))
1962 /* Don't try to handle division or shifting of infinities. */
1963 if ((code == TRUNC_DIV_EXPR
1964 || code == FLOOR_DIV_EXPR
1965 || code == CEIL_DIV_EXPR
1966 || code == EXACT_DIV_EXPR
1967 || code == ROUND_DIV_EXPR
1968 || code == RSHIFT_EXPR)
1969 && (is_overflow_infinity (val1)
1970 || is_overflow_infinity (val2)))
1973 /* Notice that we only need to handle the restricted set of
1974 operations handled by extract_range_from_binary_expr.
1975 Among them, only multiplication, addition and subtraction
1976 can yield overflow without overflown operands because we
1977 are working with integral types only... except in the
1978 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1979 for division too. */
1981 /* For multiplication, the sign of the overflow is given
1982 by the comparison of the signs of the operands. */
1983 if ((code == MULT_EXPR && sgn1 == sgn2)
1984 /* For addition, the operands must be of the same sign
1985 to yield an overflow. Its sign is therefore that
1986 of one of the operands, for example the first. For
1987 infinite operands X + -INF is negative, not positive. */
1988 || (code == PLUS_EXPR
1990 ? !is_negative_overflow_infinity (val2)
1991 : is_positive_overflow_infinity (val2)))
1992 /* For subtraction, non-infinite operands must be of
1993 different signs to yield an overflow. Its sign is
1994 therefore that of the first operand or the opposite of
1995 that of the second operand. A first operand of 0 counts
1996 as positive here, for the corner case 0 - (-INF), which
1997 overflows, but must yield +INF. For infinite operands 0
1998 - INF is negative, not positive. */
1999 || (code == MINUS_EXPR
2001 ? !is_positive_overflow_infinity (val2)
2002 : is_negative_overflow_infinity (val2)))
2003 /* We only get in here with positive shift count, so the
2004 overflow direction is the same as the sign of val1.
2005 Actually rshift does not overflow at all, but we only
2006 handle the case of shifting overflowed -INF and +INF. */
2007 || (code == RSHIFT_EXPR
2009 /* For division, the only case is -INF / -1 = +INF. */
2010 || code == TRUNC_DIV_EXPR
2011 || code == FLOOR_DIV_EXPR
2012 || code == CEIL_DIV_EXPR
2013 || code == EXACT_DIV_EXPR
2014 || code == ROUND_DIV_EXPR)
2015 return (needs_overflow_infinity (TREE_TYPE (res))
2016 ? positive_overflow_infinity (TREE_TYPE (res))
2017 : TYPE_MAX_VALUE (TREE_TYPE (res)));
2019 return (needs_overflow_infinity (TREE_TYPE (res))
2020 ? negative_overflow_infinity (TREE_TYPE (res))
2021 : TYPE_MIN_VALUE (TREE_TYPE (res)));
2028 /* Extract range information from a binary expression EXPR based on
2029 the ranges of each of its operands and the expression code. */
2032 extract_range_from_binary_expr (value_range_t *vr,
2033 enum tree_code code,
2034 tree expr_type, tree op0, tree op1)
2036 enum value_range_type type;
2039 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2040 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2042 /* Not all binary expressions can be applied to ranges in a
2043 meaningful way. Handle only arithmetic operations. */
2044 if (code != PLUS_EXPR
2045 && code != MINUS_EXPR
2046 && code != POINTER_PLUS_EXPR
2047 && code != MULT_EXPR
2048 && code != TRUNC_DIV_EXPR
2049 && code != FLOOR_DIV_EXPR
2050 && code != CEIL_DIV_EXPR
2051 && code != EXACT_DIV_EXPR
2052 && code != ROUND_DIV_EXPR
2053 && code != RSHIFT_EXPR
2056 && code != BIT_AND_EXPR
2057 && code != TRUTH_AND_EXPR
2058 && code != TRUTH_OR_EXPR)
2060 /* We can still do constant propagation here. */
2061 tree const_op0 = op_with_constant_singleton_value_range (op0);
2062 tree const_op1 = op_with_constant_singleton_value_range (op1);
2063 if (const_op0 || const_op1)
2065 tree tem = fold_binary (code, expr_type,
2066 const_op0 ? const_op0 : op0,
2067 const_op1 ? const_op1 : op1);
2069 && is_gimple_min_invariant (tem)
2070 && !is_overflow_infinity (tem))
2072 set_value_range (vr, VR_RANGE, tem, tem, NULL);
2076 set_value_range_to_varying (vr);
2080 /* Get value ranges for each operand. For constant operands, create
2081 a new value range with the operand to simplify processing. */
2082 if (TREE_CODE (op0) == SSA_NAME)
2083 vr0 = *(get_value_range (op0));
2084 else if (is_gimple_min_invariant (op0))
2085 set_value_range_to_value (&vr0, op0, NULL);
2087 set_value_range_to_varying (&vr0);
2089 if (TREE_CODE (op1) == SSA_NAME)
2090 vr1 = *(get_value_range (op1));
2091 else if (is_gimple_min_invariant (op1))
2092 set_value_range_to_value (&vr1, op1, NULL);
2094 set_value_range_to_varying (&vr1);
2096 /* If either range is UNDEFINED, so is the result. */
2097 if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED)
2099 set_value_range_to_undefined (vr);
2103 /* The type of the resulting value range defaults to VR0.TYPE. */
2106 /* Refuse to operate on VARYING ranges, ranges of different kinds
2107 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
2108 because we may be able to derive a useful range even if one of
2109 the operands is VR_VARYING or symbolic range. TODO, we may be
2110 able to derive anti-ranges in some cases. */
2111 if (code != BIT_AND_EXPR
2112 && code != TRUTH_AND_EXPR
2113 && code != TRUTH_OR_EXPR
2114 && (vr0.type == VR_VARYING
2115 || vr1.type == VR_VARYING
2116 || vr0.type != vr1.type
2117 || symbolic_range_p (&vr0)
2118 || symbolic_range_p (&vr1)))
2120 set_value_range_to_varying (vr);
2124 /* Now evaluate the expression to determine the new range. */
2125 if (POINTER_TYPE_P (expr_type)
2126 || POINTER_TYPE_P (TREE_TYPE (op0))
2127 || POINTER_TYPE_P (TREE_TYPE (op1)))
2129 if (code == MIN_EXPR || code == MAX_EXPR)
2131 /* For MIN/MAX expressions with pointers, we only care about
2132 nullness, if both are non null, then the result is nonnull.
2133 If both are null, then the result is null. Otherwise they
2135 if (range_is_nonnull (&vr0) && range_is_nonnull (&vr1))
2136 set_value_range_to_nonnull (vr, expr_type);
2137 else if (range_is_null (&vr0) && range_is_null (&vr1))
2138 set_value_range_to_null (vr, expr_type);
2140 set_value_range_to_varying (vr);
2144 gcc_assert (code == POINTER_PLUS_EXPR);
2145 /* For pointer types, we are really only interested in asserting
2146 whether the expression evaluates to non-NULL. */
2147 if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
2148 set_value_range_to_nonnull (vr, expr_type);
2149 else if (range_is_null (&vr0) && range_is_null (&vr1))
2150 set_value_range_to_null (vr, expr_type);
2152 set_value_range_to_varying (vr);
2157 /* For integer ranges, apply the operation to each end of the
2158 range and see what we end up with. */
2159 if (code == TRUTH_AND_EXPR
2160 || code == TRUTH_OR_EXPR)
2162 /* If one of the operands is zero, we know that the whole
2163 expression evaluates zero. */
2164 if (code == TRUTH_AND_EXPR
2165 && ((vr0.type == VR_RANGE
2166 && integer_zerop (vr0.min)
2167 && integer_zerop (vr0.max))
2168 || (vr1.type == VR_RANGE
2169 && integer_zerop (vr1.min)
2170 && integer_zerop (vr1.max))))
2173 min = max = build_int_cst (expr_type, 0);
2175 /* If one of the operands is one, we know that the whole
2176 expression evaluates one. */
2177 else if (code == TRUTH_OR_EXPR
2178 && ((vr0.type == VR_RANGE
2179 && integer_onep (vr0.min)
2180 && integer_onep (vr0.max))
2181 || (vr1.type == VR_RANGE
2182 && integer_onep (vr1.min)
2183 && integer_onep (vr1.max))))
2186 min = max = build_int_cst (expr_type, 1);
2188 else if (vr0.type != VR_VARYING
2189 && vr1.type != VR_VARYING
2190 && vr0.type == vr1.type
2191 && !symbolic_range_p (&vr0)
2192 && !overflow_infinity_range_p (&vr0)
2193 && !symbolic_range_p (&vr1)
2194 && !overflow_infinity_range_p (&vr1))
2196 /* Boolean expressions cannot be folded with int_const_binop. */
2197 min = fold_binary (code, expr_type, vr0.min, vr1.min);
2198 max = fold_binary (code, expr_type, vr0.max, vr1.max);
2202 /* The result of a TRUTH_*_EXPR is always true or false. */
2203 set_value_range_to_truthvalue (vr, expr_type);
2207 else if (code == PLUS_EXPR
2209 || code == MAX_EXPR)
2211 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
2212 VR_VARYING. It would take more effort to compute a precise
2213 range for such a case. For example, if we have op0 == 1 and
2214 op1 == -1 with their ranges both being ~[0,0], we would have
2215 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
2216 Note that we are guaranteed to have vr0.type == vr1.type at
2218 if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
2220 set_value_range_to_varying (vr);
2224 /* For operations that make the resulting range directly
2225 proportional to the original ranges, apply the operation to
2226 the same end of each range. */
2227 min = vrp_int_const_binop (code, vr0.min, vr1.min);
2228 max = vrp_int_const_binop (code, vr0.max, vr1.max);
2230 else if (code == MULT_EXPR
2231 || code == TRUNC_DIV_EXPR
2232 || code == FLOOR_DIV_EXPR
2233 || code == CEIL_DIV_EXPR
2234 || code == EXACT_DIV_EXPR
2235 || code == ROUND_DIV_EXPR
2236 || code == RSHIFT_EXPR)
2242 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
2243 drop to VR_VARYING. It would take more effort to compute a
2244 precise range for such a case. For example, if we have
2245 op0 == 65536 and op1 == 65536 with their ranges both being
2246 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
2247 we cannot claim that the product is in ~[0,0]. Note that we
2248 are guaranteed to have vr0.type == vr1.type at this
2250 if (code == MULT_EXPR
2251 && vr0.type == VR_ANTI_RANGE
2252 && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0)))
2254 set_value_range_to_varying (vr);
2258 /* If we have a RSHIFT_EXPR with any shift values outside [0..prec-1],
2259 then drop to VR_VARYING. Outside of this range we get undefined
2260 behavior from the shift operation. We cannot even trust
2261 SHIFT_COUNT_TRUNCATED at this stage, because that applies to rtl
2262 shifts, and the operation at the tree level may be widened. */
2263 if (code == RSHIFT_EXPR)
2265 if (vr1.type == VR_ANTI_RANGE
2266 || !vrp_expr_computes_nonnegative (op1, &sop)
2268 (build_int_cst (TREE_TYPE (vr1.max),
2269 TYPE_PRECISION (expr_type) - 1),
2272 set_value_range_to_varying (vr);
2277 /* Multiplications and divisions are a bit tricky to handle,
2278 depending on the mix of signs we have in the two ranges, we
2279 need to operate on different values to get the minimum and
2280 maximum values for the new range. One approach is to figure
2281 out all the variations of range combinations and do the
2284 However, this involves several calls to compare_values and it
2285 is pretty convoluted. It's simpler to do the 4 operations
2286 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
2287 MAX1) and then figure the smallest and largest values to form
2290 /* Divisions by zero result in a VARYING value. */
2291 else if (code != MULT_EXPR
2292 && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
2294 set_value_range_to_varying (vr);
2298 /* Compute the 4 cross operations. */
2300 val[0] = vrp_int_const_binop (code, vr0.min, vr1.min);
2301 if (val[0] == NULL_TREE)
2304 if (vr1.max == vr1.min)
2308 val[1] = vrp_int_const_binop (code, vr0.min, vr1.max);
2309 if (val[1] == NULL_TREE)
2313 if (vr0.max == vr0.min)
2317 val[2] = vrp_int_const_binop (code, vr0.max, vr1.min);
2318 if (val[2] == NULL_TREE)
2322 if (vr0.min == vr0.max || vr1.min == vr1.max)
2326 val[3] = vrp_int_const_binop (code, vr0.max, vr1.max);
2327 if (val[3] == NULL_TREE)
2333 set_value_range_to_varying (vr);
2337 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
2341 for (i = 1; i < 4; i++)
2343 if (!is_gimple_min_invariant (min)
2344 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
2345 || !is_gimple_min_invariant (max)
2346 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
2351 if (!is_gimple_min_invariant (val[i])
2352 || (TREE_OVERFLOW (val[i])
2353 && !is_overflow_infinity (val[i])))
2355 /* If we found an overflowed value, set MIN and MAX
2356 to it so that we set the resulting range to
2362 if (compare_values (val[i], min) == -1)
2365 if (compare_values (val[i], max) == 1)
2370 else if (code == MINUS_EXPR)
2372 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
2373 VR_VARYING. It would take more effort to compute a precise
2374 range for such a case. For example, if we have op0 == 1 and
2375 op1 == 1 with their ranges both being ~[0,0], we would have
2376 op0 - op1 == 0, so we cannot claim that the difference is in
2377 ~[0,0]. Note that we are guaranteed to have
2378 vr0.type == vr1.type at this point. */
2379 if (vr0.type == VR_ANTI_RANGE)
2381 set_value_range_to_varying (vr);
2385 /* For MINUS_EXPR, apply the operation to the opposite ends of
2387 min = vrp_int_const_binop (code, vr0.min, vr1.max);
2388 max = vrp_int_const_binop (code, vr0.max, vr1.min);
2390 else if (code == BIT_AND_EXPR)
2392 if (vr0.type == VR_RANGE
2393 && vr0.min == vr0.max
2394 && TREE_CODE (vr0.max) == INTEGER_CST
2395 && !TREE_OVERFLOW (vr0.max)
2396 && tree_int_cst_sgn (vr0.max) >= 0)
2398 min = build_int_cst (expr_type, 0);
2401 else if (vr1.type == VR_RANGE
2402 && vr1.min == vr1.max
2403 && TREE_CODE (vr1.max) == INTEGER_CST
2404 && !TREE_OVERFLOW (vr1.max)
2405 && tree_int_cst_sgn (vr1.max) >= 0)
2408 min = build_int_cst (expr_type, 0);
2413 set_value_range_to_varying (vr);
2420 /* If either MIN or MAX overflowed, then set the resulting range to
2421 VARYING. But we do accept an overflow infinity
2423 if (min == NULL_TREE
2424 || !is_gimple_min_invariant (min)
2425 || (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
2427 || !is_gimple_min_invariant (max)
2428 || (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
2430 set_value_range_to_varying (vr);
2436 2) [-INF, +-INF(OVF)]
2437 3) [+-INF(OVF), +INF]
2438 4) [+-INF(OVF), +-INF(OVF)]
2439 We learn nothing when we have INF and INF(OVF) on both sides.
2440 Note that we do accept [-INF, -INF] and [+INF, +INF] without
2442 if ((vrp_val_is_min (min) || is_overflow_infinity (min))
2443 && (vrp_val_is_max (max) || is_overflow_infinity (max)))
2445 set_value_range_to_varying (vr);
2449 cmp = compare_values (min, max);
2450 if (cmp == -2 || cmp == 1)
2452 /* If the new range has its limits swapped around (MIN > MAX),
2453 then the operation caused one of them to wrap around, mark
2454 the new range VARYING. */
2455 set_value_range_to_varying (vr);
2458 set_value_range (vr, type, min, max, NULL);
2462 /* Extract range information from a unary expression EXPR based on
2463 the range of its operand and the expression code. */
2466 extract_range_from_unary_expr (value_range_t *vr, enum tree_code code,
2467 tree type, tree op0)
2471 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2473 /* Refuse to operate on certain unary expressions for which we
2474 cannot easily determine a resulting range. */
2475 if (code == FIX_TRUNC_EXPR
2476 || code == FLOAT_EXPR
2477 || code == BIT_NOT_EXPR
2478 || code == CONJ_EXPR)
2480 /* We can still do constant propagation here. */
2481 if ((op0 = op_with_constant_singleton_value_range (op0)) != NULL_TREE)
2483 tree tem = fold_unary (code, type, op0);
2485 && is_gimple_min_invariant (tem)
2486 && !is_overflow_infinity (tem))
2488 set_value_range (vr, VR_RANGE, tem, tem, NULL);
2492 set_value_range_to_varying (vr);
2496 /* Get value ranges for the operand. For constant operands, create
2497 a new value range with the operand to simplify processing. */
2498 if (TREE_CODE (op0) == SSA_NAME)
2499 vr0 = *(get_value_range (op0));
2500 else if (is_gimple_min_invariant (op0))
2501 set_value_range_to_value (&vr0, op0, NULL);
2503 set_value_range_to_varying (&vr0);
2505 /* If VR0 is UNDEFINED, so is the result. */
2506 if (vr0.type == VR_UNDEFINED)
2508 set_value_range_to_undefined (vr);
2512 /* Refuse to operate on symbolic ranges, or if neither operand is
2513 a pointer or integral type. */
2514 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0))
2515 && !POINTER_TYPE_P (TREE_TYPE (op0)))
2516 || (vr0.type != VR_VARYING
2517 && symbolic_range_p (&vr0)))
2519 set_value_range_to_varying (vr);
2523 /* If the expression involves pointers, we are only interested in
2524 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
2525 if (POINTER_TYPE_P (type) || POINTER_TYPE_P (TREE_TYPE (op0)))
2530 if (range_is_nonnull (&vr0)
2531 || (tree_unary_nonzero_warnv_p (code, type, op0, &sop)
2533 set_value_range_to_nonnull (vr, type);
2534 else if (range_is_null (&vr0))
2535 set_value_range_to_null (vr, type);
2537 set_value_range_to_varying (vr);
2542 /* Handle unary expressions on integer ranges. */
2543 if (CONVERT_EXPR_CODE_P (code)
2544 && INTEGRAL_TYPE_P (type)
2545 && INTEGRAL_TYPE_P (TREE_TYPE (op0)))
2547 tree inner_type = TREE_TYPE (op0);
2548 tree outer_type = type;
2550 /* Always use base-types here. This is important for the
2551 correct signedness. */
2552 if (TREE_TYPE (inner_type))
2553 inner_type = TREE_TYPE (inner_type);
2554 if (TREE_TYPE (outer_type))
2555 outer_type = TREE_TYPE (outer_type);
2557 /* If VR0 is varying and we increase the type precision, assume
2558 a full range for the following transformation. */
2559 if (vr0.type == VR_VARYING
2560 && TYPE_PRECISION (inner_type) < TYPE_PRECISION (outer_type))
2562 vr0.type = VR_RANGE;
2563 vr0.min = TYPE_MIN_VALUE (inner_type);
2564 vr0.max = TYPE_MAX_VALUE (inner_type);
2567 /* If VR0 is a constant range or anti-range and the conversion is
2568 not truncating we can convert the min and max values and
2569 canonicalize the resulting range. Otherwise we can do the
2570 conversion if the size of the range is less than what the
2571 precision of the target type can represent and the range is
2572 not an anti-range. */
2573 if ((vr0.type == VR_RANGE
2574 || vr0.type == VR_ANTI_RANGE)
2575 && TREE_CODE (vr0.min) == INTEGER_CST
2576 && TREE_CODE (vr0.max) == INTEGER_CST
2577 && !is_overflow_infinity (vr0.min)
2578 && !is_overflow_infinity (vr0.max)
2579 && (TYPE_PRECISION (outer_type) >= TYPE_PRECISION (inner_type)
2580 || (vr0.type == VR_RANGE
2581 && integer_zerop (int_const_binop (RSHIFT_EXPR,
2582 int_const_binop (MINUS_EXPR, vr0.max, vr0.min, 0),
2583 size_int (TYPE_PRECISION (outer_type)), 0)))))
2585 tree new_min, new_max;
2586 new_min = force_fit_type_double (outer_type,
2587 TREE_INT_CST_LOW (vr0.min),
2588 TREE_INT_CST_HIGH (vr0.min), 0, 0);
2589 new_max = force_fit_type_double (outer_type,
2590 TREE_INT_CST_LOW (vr0.max),
2591 TREE_INT_CST_HIGH (vr0.max), 0, 0);
2592 set_and_canonicalize_value_range (vr, vr0.type,
2593 new_min, new_max, NULL);
2597 set_value_range_to_varying (vr);
2601 /* Conversion of a VR_VARYING value to a wider type can result
2602 in a usable range. So wait until after we've handled conversions
2603 before dropping the result to VR_VARYING if we had a source
2604 operand that is VR_VARYING. */
2605 if (vr0.type == VR_VARYING)
2607 set_value_range_to_varying (vr);
2611 /* Apply the operation to each end of the range and see what we end
2613 if (code == NEGATE_EXPR
2614 && !TYPE_UNSIGNED (type))
2616 /* NEGATE_EXPR flips the range around. We need to treat
2617 TYPE_MIN_VALUE specially. */
2618 if (is_positive_overflow_infinity (vr0.max))
2619 min = negative_overflow_infinity (type);
2620 else if (is_negative_overflow_infinity (vr0.max))
2621 min = positive_overflow_infinity (type);
2622 else if (!vrp_val_is_min (vr0.max))
2623 min = fold_unary_to_constant (code, type, vr0.max);
2624 else if (needs_overflow_infinity (type))
2626 if (supports_overflow_infinity (type)
2627 && !is_overflow_infinity (vr0.min)
2628 && !vrp_val_is_min (vr0.min))
2629 min = positive_overflow_infinity (type);
2632 set_value_range_to_varying (vr);
2637 min = TYPE_MIN_VALUE (type);
2639 if (is_positive_overflow_infinity (vr0.min))
2640 max = negative_overflow_infinity (type);
2641 else if (is_negative_overflow_infinity (vr0.min))
2642 max = positive_overflow_infinity (type);
2643 else if (!vrp_val_is_min (vr0.min))
2644 max = fold_unary_to_constant (code, type, vr0.min);
2645 else if (needs_overflow_infinity (type))
2647 if (supports_overflow_infinity (type))
2648 max = positive_overflow_infinity (type);
2651 set_value_range_to_varying (vr);
2656 max = TYPE_MIN_VALUE (type);
2658 else if (code == NEGATE_EXPR
2659 && TYPE_UNSIGNED (type))
2661 if (!range_includes_zero_p (&vr0))
2663 max = fold_unary_to_constant (code, type, vr0.min);
2664 min = fold_unary_to_constant (code, type, vr0.max);
2668 if (range_is_null (&vr0))
2669 set_value_range_to_null (vr, type);
2671 set_value_range_to_varying (vr);
2675 else if (code == ABS_EXPR
2676 && !TYPE_UNSIGNED (type))
2678 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
2680 if (!TYPE_OVERFLOW_UNDEFINED (type)
2681 && ((vr0.type == VR_RANGE
2682 && vrp_val_is_min (vr0.min))
2683 || (vr0.type == VR_ANTI_RANGE
2684 && !vrp_val_is_min (vr0.min)
2685 && !range_includes_zero_p (&vr0))))
2687 set_value_range_to_varying (vr);
2691 /* ABS_EXPR may flip the range around, if the original range
2692 included negative values. */
2693 if (is_overflow_infinity (vr0.min))
2694 min = positive_overflow_infinity (type);
2695 else if (!vrp_val_is_min (vr0.min))
2696 min = fold_unary_to_constant (code, type, vr0.min);
2697 else if (!needs_overflow_infinity (type))
2698 min = TYPE_MAX_VALUE (type);
2699 else if (supports_overflow_infinity (type))
2700 min = positive_overflow_infinity (type);
2703 set_value_range_to_varying (vr);
2707 if (is_overflow_infinity (vr0.max))
2708 max = positive_overflow_infinity (type);
2709 else if (!vrp_val_is_min (vr0.max))
2710 max = fold_unary_to_constant (code, type, vr0.max);
2711 else if (!needs_overflow_infinity (type))
2712 max = TYPE_MAX_VALUE (type);
2713 else if (supports_overflow_infinity (type)
2714 /* We shouldn't generate [+INF, +INF] as set_value_range
2715 doesn't like this and ICEs. */
2716 && !is_positive_overflow_infinity (min))
2717 max = positive_overflow_infinity (type);
2720 set_value_range_to_varying (vr);
2724 cmp = compare_values (min, max);
2726 /* If a VR_ANTI_RANGEs contains zero, then we have
2727 ~[-INF, min(MIN, MAX)]. */
2728 if (vr0.type == VR_ANTI_RANGE)
2730 if (range_includes_zero_p (&vr0))
2732 /* Take the lower of the two values. */
2736 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
2737 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
2738 flag_wrapv is set and the original anti-range doesn't include
2739 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
2740 if (TYPE_OVERFLOW_WRAPS (type))
2742 tree type_min_value = TYPE_MIN_VALUE (type);
2744 min = (vr0.min != type_min_value
2745 ? int_const_binop (PLUS_EXPR, type_min_value,
2746 integer_one_node, 0)
2751 if (overflow_infinity_range_p (&vr0))
2752 min = negative_overflow_infinity (type);
2754 min = TYPE_MIN_VALUE (type);
2759 /* All else has failed, so create the range [0, INF], even for
2760 flag_wrapv since TYPE_MIN_VALUE is in the original
2762 vr0.type = VR_RANGE;
2763 min = build_int_cst (type, 0);
2764 if (needs_overflow_infinity (type))
2766 if (supports_overflow_infinity (type))
2767 max = positive_overflow_infinity (type);
2770 set_value_range_to_varying (vr);
2775 max = TYPE_MAX_VALUE (type);
2779 /* If the range contains zero then we know that the minimum value in the
2780 range will be zero. */
2781 else if (range_includes_zero_p (&vr0))
2785 min = build_int_cst (type, 0);
2789 /* If the range was reversed, swap MIN and MAX. */
2800 /* Otherwise, operate on each end of the range. */
2801 min = fold_unary_to_constant (code, type, vr0.min);
2802 max = fold_unary_to_constant (code, type, vr0.max);
2804 if (needs_overflow_infinity (type))
2806 gcc_assert (code != NEGATE_EXPR && code != ABS_EXPR);
2808 /* If both sides have overflowed, we don't know
2810 if ((is_overflow_infinity (vr0.min)
2811 || TREE_OVERFLOW (min))
2812 && (is_overflow_infinity (vr0.max)
2813 || TREE_OVERFLOW (max)))
2815 set_value_range_to_varying (vr);
2819 if (is_overflow_infinity (vr0.min))
2821 else if (TREE_OVERFLOW (min))
2823 if (supports_overflow_infinity (type))
2824 min = (tree_int_cst_sgn (min) >= 0
2825 ? positive_overflow_infinity (TREE_TYPE (min))
2826 : negative_overflow_infinity (TREE_TYPE (min)));
2829 set_value_range_to_varying (vr);
2834 if (is_overflow_infinity (vr0.max))
2836 else if (TREE_OVERFLOW (max))
2838 if (supports_overflow_infinity (type))
2839 max = (tree_int_cst_sgn (max) >= 0
2840 ? positive_overflow_infinity (TREE_TYPE (max))
2841 : negative_overflow_infinity (TREE_TYPE (max)));
2844 set_value_range_to_varying (vr);
2851 cmp = compare_values (min, max);
2852 if (cmp == -2 || cmp == 1)
2854 /* If the new range has its limits swapped around (MIN > MAX),
2855 then the operation caused one of them to wrap around, mark
2856 the new range VARYING. */
2857 set_value_range_to_varying (vr);
2860 set_value_range (vr, vr0.type, min, max, NULL);
2864 /* Extract range information from a conditional expression EXPR based on
2865 the ranges of each of its operands and the expression code. */
2868 extract_range_from_cond_expr (value_range_t *vr, tree expr)
2871 value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2872 value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
2874 /* Get value ranges for each operand. For constant operands, create
2875 a new value range with the operand to simplify processing. */
2876 op0 = COND_EXPR_THEN (expr);
2877 if (TREE_CODE (op0) == SSA_NAME)
2878 vr0 = *(get_value_range (op0));
2879 else if (is_gimple_min_invariant (op0))
2880 set_value_range_to_value (&vr0, op0, NULL);
2882 set_value_range_to_varying (&vr0);
2884 op1 = COND_EXPR_ELSE (expr);
2885 if (TREE_CODE (op1) == SSA_NAME)
2886 vr1 = *(get_value_range (op1));
2887 else if (is_gimple_min_invariant (op1))
2888 set_value_range_to_value (&vr1, op1, NULL);
2890 set_value_range_to_varying (&vr1);
2892 /* The resulting value range is the union of the operand ranges */
2893 vrp_meet (&vr0, &vr1);
2894 copy_value_range (vr, &vr0);
2898 /* Extract range information from a comparison expression EXPR based
2899 on the range of its operand and the expression code. */
2902 extract_range_from_comparison (value_range_t *vr, enum tree_code code,
2903 tree type, tree op0, tree op1)
2908 val = vrp_evaluate_conditional_warnv_with_ops (code, op0, op1, false, &sop);
2910 /* A disadvantage of using a special infinity as an overflow
2911 representation is that we lose the ability to record overflow
2912 when we don't have an infinity. So we have to ignore a result
2913 which relies on overflow. */
2915 if (val && !is_overflow_infinity (val) && !sop)
2917 /* Since this expression was found on the RHS of an assignment,
2918 its type may be different from _Bool. Convert VAL to EXPR's
2920 val = fold_convert (type, val);
2921 if (is_gimple_min_invariant (val))
2922 set_value_range_to_value (vr, val, vr->equiv);
2924 set_value_range (vr, VR_RANGE, val, val, vr->equiv);
2927 /* The result of a comparison is always true or false. */
2928 set_value_range_to_truthvalue (vr, type);
2931 /* Try to derive a nonnegative or nonzero range out of STMT relying
2932 primarily on generic routines in fold in conjunction with range data.
2933 Store the result in *VR */
2936 extract_range_basic (value_range_t *vr, gimple stmt)
2939 tree type = gimple_expr_type (stmt);
2941 if (INTEGRAL_TYPE_P (type)
2942 && gimple_stmt_nonnegative_warnv_p (stmt, &sop))
2943 set_value_range_to_nonnegative (vr, type,
2944 sop || stmt_overflow_infinity (stmt));
2945 else if (vrp_stmt_computes_nonzero (stmt, &sop)
2947 set_value_range_to_nonnull (vr, type);
2949 set_value_range_to_varying (vr);
2953 /* Try to compute a useful range out of assignment STMT and store it
2957 extract_range_from_assignment (value_range_t *vr, gimple stmt)
2959 enum tree_code code = gimple_assign_rhs_code (stmt);
2961 if (code == ASSERT_EXPR)
2962 extract_range_from_assert (vr, gimple_assign_rhs1 (stmt));
2963 else if (code == SSA_NAME)
2964 extract_range_from_ssa_name (vr, gimple_assign_rhs1 (stmt));
2965 else if (TREE_CODE_CLASS (code) == tcc_binary
2966 || code == TRUTH_AND_EXPR
2967 || code == TRUTH_OR_EXPR
2968 || code == TRUTH_XOR_EXPR)
2969 extract_range_from_binary_expr (vr, gimple_assign_rhs_code (stmt),
2970 gimple_expr_type (stmt),
2971 gimple_assign_rhs1 (stmt),
2972 gimple_assign_rhs2 (stmt));
2973 else if (TREE_CODE_CLASS (code) == tcc_unary)
2974 extract_range_from_unary_expr (vr, gimple_assign_rhs_code (stmt),
2975 gimple_expr_type (stmt),
2976 gimple_assign_rhs1 (stmt));
2977 else if (code == COND_EXPR)
2978 extract_range_from_cond_expr (vr, gimple_assign_rhs1 (stmt));
2979 else if (TREE_CODE_CLASS (code) == tcc_comparison)
2980 extract_range_from_comparison (vr, gimple_assign_rhs_code (stmt),
2981 gimple_expr_type (stmt),
2982 gimple_assign_rhs1 (stmt),
2983 gimple_assign_rhs2 (stmt));
2984 else if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS
2985 && is_gimple_min_invariant (gimple_assign_rhs1 (stmt)))
2986 set_value_range_to_value (vr, gimple_assign_rhs1 (stmt), NULL);
2988 set_value_range_to_varying (vr);
2990 if (vr->type == VR_VARYING)
2991 extract_range_basic (vr, stmt);
2994 /* Given a range VR, a LOOP and a variable VAR, determine whether it
2995 would be profitable to adjust VR using scalar evolution information
2996 for VAR. If so, update VR with the new limits. */
2999 adjust_range_with_scev (value_range_t *vr, struct loop *loop,
3000 gimple stmt, tree var)
3002 tree init, step, chrec, tmin, tmax, min, max, type;
3003 enum ev_direction dir;
3005 /* TODO. Don't adjust anti-ranges. An anti-range may provide
3006 better opportunities than a regular range, but I'm not sure. */
3007 if (vr->type == VR_ANTI_RANGE)
3010 chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
3012 /* Like in PR19590, scev can return a constant function. */
3013 if (is_gimple_min_invariant (chrec))
3015 set_value_range_to_value (vr, chrec, vr->equiv);
3019 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
3022 init = initial_condition_in_loop_num (chrec, loop->num);
3023 step = evolution_part_in_loop_num (chrec, loop->num);
3025 /* If STEP is symbolic, we can't know whether INIT will be the
3026 minimum or maximum value in the range. Also, unless INIT is
3027 a simple expression, compare_values and possibly other functions
3028 in tree-vrp won't be able to handle it. */
3029 if (step == NULL_TREE
3030 || !is_gimple_min_invariant (step)
3031 || !valid_value_p (init))
3034 dir = scev_direction (chrec);
3035 if (/* Do not adjust ranges if we do not know whether the iv increases
3036 or decreases, ... */
3037 dir == EV_DIR_UNKNOWN
3038 /* ... or if it may wrap. */
3039 || scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec),
3043 /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of
3044 negative_overflow_infinity and positive_overflow_infinity,
3045 because we have concluded that the loop probably does not
3048 type = TREE_TYPE (var);
3049 if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type))
3050 tmin = lower_bound_in_type (type, type);
3052 tmin = TYPE_MIN_VALUE (type);
3053 if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type))
3054 tmax = upper_bound_in_type (type, type);
3056 tmax = TYPE_MAX_VALUE (type);
3058 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
3063 /* For VARYING or UNDEFINED ranges, just about anything we get
3064 from scalar evolutions should be better. */
3066 if (dir == EV_DIR_DECREASES)
3071 /* If we would create an invalid range, then just assume we
3072 know absolutely nothing. This may be over-conservative,
3073 but it's clearly safe, and should happen only in unreachable
3074 parts of code, or for invalid programs. */
3075 if (compare_values (min, max) == 1)
3078 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
3080 else if (vr->type == VR_RANGE)
3085 if (dir == EV_DIR_DECREASES)
3087 /* INIT is the maximum value. If INIT is lower than VR->MAX
3088 but no smaller than VR->MIN, set VR->MAX to INIT. */
3089 if (compare_values (init, max) == -1)
3093 /* If we just created an invalid range with the minimum
3094 greater than the maximum, we fail conservatively.
3095 This should happen only in unreachable
3096 parts of code, or for invalid programs. */
3097 if (compare_values (min, max) == 1)
3101 /* According to the loop information, the variable does not
3102 overflow. If we think it does, probably because of an
3103 overflow due to arithmetic on a different INF value,
3105 if (is_negative_overflow_infinity (min))
3110 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
3111 if (compare_values (init, min) == 1)
3115 /* Again, avoid creating invalid range by failing. */
3116 if (compare_values (min, max) == 1)
3120 if (is_positive_overflow_infinity (max))
3124 set_value_range (vr, VR_RANGE, min, max, vr->equiv);
3128 /* Return true if VAR may overflow at STMT. This checks any available
3129 loop information to see if we can determine that VAR does not
3133 vrp_var_may_overflow (tree var, gimple stmt)
3136 tree chrec, init, step;
3138 if (current_loops == NULL)
3141 l = loop_containing_stmt (stmt);
3145 chrec = instantiate_parameters (l, analyze_scalar_evolution (l, var));
3146 if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
3149 init = initial_condition_in_loop_num (chrec, l->num);
3150 step = evolution_part_in_loop_num (chrec, l->num);
3152 if (step == NULL_TREE
3153 || !is_gimple_min_invariant (step)
3154 || !valid_value_p (init))
3157 /* If we get here, we know something useful about VAR based on the
3158 loop information. If it wraps, it may overflow. */
3160 if (scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec),
3164 if (dump_file && (dump_flags & TDF_DETAILS) != 0)
3166 print_generic_expr (dump_file, var, 0);
3167 fprintf (dump_file, ": loop information indicates does not overflow\n");
3174 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
3176 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
3177 all the values in the ranges.
3179 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
3181 - Return NULL_TREE if it is not always possible to determine the
3182 value of the comparison.
3184 Also set *STRICT_OVERFLOW_P to indicate whether a range with an
3185 overflow infinity was used in the test. */
3189 compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1,
3190 bool *strict_overflow_p)
3192 /* VARYING or UNDEFINED ranges cannot be compared. */
3193 if (vr0->type == VR_VARYING
3194 || vr0->type == VR_UNDEFINED
3195 || vr1->type == VR_VARYING
3196 || vr1->type == VR_UNDEFINED)
3199 /* Anti-ranges need to be handled separately. */
3200 if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
3202 /* If both are anti-ranges, then we cannot compute any
3204 if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
3207 /* These comparisons are never statically computable. */
3214 /* Equality can be computed only between a range and an
3215 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
3216 if (vr0->type == VR_RANGE)
3218 /* To simplify processing, make VR0 the anti-range. */
3219 value_range_t *tmp = vr0;
3224 gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
3226 if (compare_values_warnv (vr0->min, vr1->min, strict_overflow_p) == 0
3227 && compare_values_warnv (vr0->max, vr1->max, strict_overflow_p) == 0)
3228 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
3233 if (!usable_range_p (vr0, strict_overflow_p)
3234 || !usable_range_p (vr1, strict_overflow_p))
3237 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
3238 operands around and change the comparison code. */
3239 if (comp == GT_EXPR || comp == GE_EXPR)
3242 comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
3248 if (comp == EQ_EXPR)
3250 /* Equality may only be computed if both ranges represent
3251 exactly one value. */
3252 if (compare_values_warnv (vr0->min, vr0->max, strict_overflow_p) == 0
3253 && compare_values_warnv (vr1->min, vr1->max, strict_overflow_p) == 0)
3255 int cmp_min = compare_values_warnv (vr0->min, vr1->min,
3257 int cmp_max = compare_values_warnv (vr0->max, vr1->max,
3259 if (cmp_min == 0 && cmp_max == 0)
3260 return boolean_true_node;
3261 else if (cmp_min != -2 && cmp_max != -2)
3262 return boolean_false_node;
3264 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
3265 else if (compare_values_warnv (vr0->min, vr1->max,
3266 strict_overflow_p) == 1
3267 || compare_values_warnv (vr1->min, vr0->max,
3268 strict_overflow_p) == 1)
3269 return boolean_false_node;
3273 else if (comp == NE_EXPR)
3277 /* If VR0 is completely to the left or completely to the right
3278 of VR1, they are always different. Notice that we need to
3279 make sure that both comparisons yield similar results to
3280 avoid comparing values that cannot be compared at
3282 cmp1 = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
3283 cmp2 = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
3284 if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
3285 return boolean_true_node;
3287 /* If VR0 and VR1 represent a single value and are identical,
3289 else if (compare_values_warnv (vr0->min, vr0->max,
3290 strict_overflow_p) == 0
3291 && compare_values_warnv (vr1->min, vr1->max,
3292 strict_overflow_p) == 0
3293 && compare_values_warnv (vr0->min, vr1->min,
3294 strict_overflow_p) == 0
3295 && compare_values_warnv (vr0->max, vr1->max,
3296 strict_overflow_p) == 0)
3297 return boolean_false_node;
3299 /* Otherwise, they may or may not be different. */
3303 else if (comp == LT_EXPR || comp == LE_EXPR)
3307 /* If VR0 is to the left of VR1, return true. */
3308 tst = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p);
3309 if ((comp == LT_EXPR && tst == -1)
3310 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
3312 if (overflow_infinity_range_p (vr0)
3313 || overflow_infinity_range_p (vr1))
3314 *strict_overflow_p = true;
3315 return boolean_true_node;
3318 /* If VR0 is to the right of VR1, return false. */
3319 tst = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p);
3320 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
3321 || (comp == LE_EXPR && tst == 1))
3323 if (overflow_infinity_range_p (vr0)
3324 || overflow_infinity_range_p (vr1))
3325 *strict_overflow_p = true;
3326 return boolean_false_node;
3329 /* Otherwise, we don't know. */
3337 /* Given a value range VR, a value VAL and a comparison code COMP, return
3338 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
3339 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
3340 always returns false. Return NULL_TREE if it is not always
3341 possible to determine the value of the comparison. Also set
3342 *STRICT_OVERFLOW_P to indicate whether a range with an overflow
3343 infinity was used in the test. */
3346 compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val,
3347 bool *strict_overflow_p)
3349 if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED)
3352 /* Anti-ranges need to be handled separately. */
3353 if (vr->type == VR_ANTI_RANGE)
3355 /* For anti-ranges, the only predicates that we can compute at
3356 compile time are equality and inequality. */
3363 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
3364 if (value_inside_range (val, vr) == 1)
3365 return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
3370 if (!usable_range_p (vr, strict_overflow_p))
3373 if (comp == EQ_EXPR)
3375 /* EQ_EXPR may only be computed if VR represents exactly
3377 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0)
3379 int cmp = compare_values_warnv (vr->min, val, strict_overflow_p);
3381 return boolean_true_node;
3382 else if (cmp == -1 || cmp == 1 || cmp == 2)
3383 return boolean_false_node;
3385 else if (compare_values_warnv (val, vr->min, strict_overflow_p) == -1
3386 || compare_values_warnv (vr->max, val, strict_overflow_p) == -1)
3387 return boolean_false_node;
3391 else if (comp == NE_EXPR)
3393 /* If VAL is not inside VR, then they are always different. */
3394 if (compare_values_warnv (vr->max, val, strict_overflow_p) == -1
3395 || compare_values_warnv (vr->min, val, strict_overflow_p) == 1)
3396 return boolean_true_node;
3398 /* If VR represents exactly one value equal to VAL, then return
3400 if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0
3401 && compare_values_warnv (vr->min, val, strict_overflow_p) == 0)
3402 return boolean_false_node;
3404 /* Otherwise, they may or may not be different. */
3407 else if (comp == LT_EXPR || comp == LE_EXPR)
3411 /* If VR is to the left of VAL, return true. */
3412 tst = compare_values_warnv (vr->max, val, strict_overflow_p);
3413 if ((comp == LT_EXPR && tst == -1)
3414 || (comp == LE_EXPR && (tst == -1 || tst == 0)))
3416 if (overflow_infinity_range_p (vr))
3417 *strict_overflow_p = true;
3418 return boolean_true_node;
3421 /* If VR is to the right of VAL, return false. */
3422 tst = compare_values_warnv (vr->min, val, strict_overflow_p);
3423 if ((comp == LT_EXPR && (tst == 0 || tst == 1))
3424 || (comp == LE_EXPR && tst == 1))
3426 if (overflow_infinity_range_p (vr))
3427 *strict_overflow_p = true;
3428 return boolean_false_node;
3431 /* Otherwise, we don't know. */
3434 else if (comp == GT_EXPR || comp == GE_EXPR)
3438 /* If VR is to the right of VAL, return true. */
3439 tst = compare_values_warnv (vr->min, val, strict_overflow_p);
3440 if ((comp == GT_EXPR && tst == 1)
3441 || (comp == GE_EXPR && (tst == 0 || tst == 1)))
3443 if (overflow_infinity_range_p (vr))
3444 *strict_overflow_p = true;
3445 return boolean_true_node;
3448 /* If VR is to the left of VAL, return false. */
3449 tst = compare_values_warnv (vr->max, val, strict_overflow_p);
3450 if ((comp == GT_EXPR && (tst == -1 || tst == 0))
3451 || (comp == GE_EXPR && tst == -1))
3453 if (overflow_infinity_range_p (vr))
3454 *strict_overflow_p = true;
3455 return boolean_false_node;
3458 /* Otherwise, we don't know. */
3466 /* Debugging dumps. */
3468 void dump_value_range (FILE *, value_range_t *);
3469 void debug_value_range (value_range_t *);
3470 void dump_all_value_ranges (FILE *);
3471 void debug_all_value_ranges (void);
3472 void dump_vr_equiv (FILE *, bitmap);
3473 void debug_vr_equiv (bitmap);
3476 /* Dump value range VR to FILE. */
3479 dump_value_range (FILE *file, value_range_t *vr)
3482 fprintf (file, "[]");
3483 else if (vr->type == VR_UNDEFINED)
3484 fprintf (file, "UNDEFINED");
3485 else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
3487 tree type = TREE_TYPE (vr->min);
3489 fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");
3491 if (is_negative_overflow_infinity (vr->min))
3492 fprintf (file, "-INF(OVF)");
3493 else if (INTEGRAL_TYPE_P (type)
3494 && !TYPE_UNSIGNED (type)
3495 && vrp_val_is_min (vr->min))
3496 fprintf (file, "-INF");
3498 print_generic_expr (file, vr->min, 0);
3500 fprintf (file, ", ");
3502 if (is_positive_overflow_infinity (vr->max))
3503 fprintf (file, "+INF(OVF)");
3504 else if (INTEGRAL_TYPE_P (type)
3505 && vrp_val_is_max (vr->max))
3506 fprintf (file, "+INF");
3508 print_generic_expr (file, vr->max, 0);
3510 fprintf (file, "]");
3517 fprintf (file, " EQUIVALENCES: { ");
3519 EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
3521 print_generic_expr (file, ssa_name (i), 0);
3522 fprintf (file, " ");
3526 fprintf (file, "} (%u elements)", c);
3529 else if (vr->type == VR_VARYING)
3530 fprintf (file, "VARYING");
3532 fprintf (file, "INVALID RANGE");
3536 /* Dump value range VR to stderr. */
3539 debug_value_range (value_range_t *vr)
3541 dump_value_range (stderr, vr);
3542 fprintf (stderr, "\n");
3546 /* Dump value ranges of all SSA_NAMEs to FILE. */
3549 dump_all_value_ranges (FILE *file)
3553 for (i = 0; i < num_ssa_names; i++)
3557 print_generic_expr (file, ssa_name (i), 0);
3558 fprintf (file, ": ");
3559 dump_value_range (file, vr_value[i]);
3560 fprintf (file, "\n");
3564 fprintf (file, "\n");
3568 /* Dump all value ranges to stderr. */
3571 debug_all_value_ranges (void)
3573 dump_all_value_ranges (stderr);
3577 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
3578 create a new SSA name N and return the assertion assignment
3579 'V = ASSERT_EXPR <V, V OP W>'. */
3582 build_assert_expr_for (tree cond, tree v)
3587 gcc_assert (TREE_CODE (v) == SSA_NAME);
3588 n = duplicate_ssa_name (v, NULL);
3590 if (COMPARISON_CLASS_P (cond))
3592 tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
3593 assertion = gimple_build_assign (n, a);
3595 else if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
3597 /* Given !V, build the assignment N = false. */
3598 tree op0 = TREE_OPERAND (cond, 0);
3599 gcc_assert (op0 == v);
3600 assertion = gimple_build_assign (n, boolean_false_node);
3602 else if (TREE_CODE (cond) == SSA_NAME)
3604 /* Given V, build the assignment N = true. */
3605 gcc_assert (v == cond);
3606 assertion = gimple_build_assign (n, boolean_true_node);
3611 SSA_NAME_DEF_STMT (n) = assertion;
3613 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
3614 operand of the ASSERT_EXPR. Register the new name and the old one
3615 in the replacement table so that we can fix the SSA web after
3616 adding all the ASSERT_EXPRs. */
3617 register_new_name_mapping (n, v);
3623 /* Return false if EXPR is a predicate expression involving floating
3627 fp_predicate (gimple stmt)
3629 GIMPLE_CHECK (stmt, GIMPLE_COND);
3631 return FLOAT_TYPE_P (TREE_TYPE (gimple_cond_lhs (stmt)));
3635 /* If the range of values taken by OP can be inferred after STMT executes,
3636 return the comparison code (COMP_CODE_P) and value (VAL_P) that
3637 describes the inferred range. Return true if a range could be
3641 infer_value_range (gimple stmt, tree op, enum tree_code *comp_code_p, tree *val_p)
3644 *comp_code_p = ERROR_MARK;
3646 /* Do not attempt to infer anything in names that flow through
3648 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
3651 /* Similarly, don't infer anything from statements that may throw
3653 if (stmt_could_throw_p (stmt))
3656 /* If STMT is the last statement of a basic block with no
3657 successors, there is no point inferring anything about any of its
3658 operands. We would not be able to find a proper insertion point
3659 for the assertion, anyway. */
3660 if (stmt_ends_bb_p (stmt) && EDGE_COUNT (gimple_bb (stmt)->succs) == 0)
3663 /* We can only assume that a pointer dereference will yield
3664 non-NULL if -fdelete-null-pointer-checks is enabled. */
3665 if (flag_delete_null_pointer_checks
3666 && POINTER_TYPE_P (TREE_TYPE (op))
3667 && gimple_code (stmt) != GIMPLE_ASM)
3669 unsigned num_uses, num_loads, num_stores;
3671 count_uses_and_derefs (op, stmt, &num_uses, &num_loads, &num_stores);
3672 if (num_loads + num_stores > 0)
3674 *val_p = build_int_cst (TREE_TYPE (op), 0);
3675 *comp_code_p = NE_EXPR;
3684 void dump_asserts_for (FILE *, tree);
3685 void debug_asserts_for (tree);
3686 void dump_all_asserts (FILE *);
3687 void debug_all_asserts (void);
3689 /* Dump all the registered assertions for NAME to FILE. */
3692 dump_asserts_for (FILE *file, tree name)
3696 fprintf (file, "Assertions to be inserted for ");
3697 print_generic_expr (file, name, 0);
3698 fprintf (file, "\n");
3700 loc = asserts_for[SSA_NAME_VERSION (name)];
3703 fprintf (file, "\t");
3704 print_gimple_stmt (file, gsi_stmt (loc->si), 0, 0);
3705 fprintf (file, "\n\tBB #%d", loc->bb->index);
3708 fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
3709 loc->e->dest->index);
3710 dump_edge_info (file, loc->e, 0);
3712 fprintf (file, "\n\tPREDICATE: ");
3713 print_generic_expr (file, name, 0);
3714 fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]);
3715 print_generic_expr (file, loc->val, 0);
3716 fprintf (file, "\n\n");
3720 fprintf (file, "\n");
3724 /* Dump all the registered assertions for NAME to stderr. */
3727 debug_asserts_for (tree name)
3729 dump_asserts_for (stderr, name);
3733 /* Dump all the registered assertions for all the names to FILE. */
3736 dump_all_asserts (FILE *file)
3741 fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
3742 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
3743 dump_asserts_for (file, ssa_name (i));
3744 fprintf (file, "\n");
3748 /* Dump all the registered assertions for all the names to stderr. */
3751 debug_all_asserts (void)
3753 dump_all_asserts (stderr);
3757 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
3758 'EXPR COMP_CODE VAL' at a location that dominates block BB or
3759 E->DEST, then register this location as a possible insertion point
3760 for ASSERT_EXPR <NAME, EXPR COMP_CODE VAL>.
3762 BB, E and SI provide the exact insertion point for the new
3763 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
3764 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
3765 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
3766 must not be NULL. */
3769 register_new_assert_for (tree name, tree expr,
3770 enum tree_code comp_code,
3774 gimple_stmt_iterator si)
3776 assert_locus_t n, loc, last_loc;
3778 basic_block dest_bb;
3780 #if defined ENABLE_CHECKING
3781 gcc_assert (bb == NULL || e == NULL);
3784 gcc_assert (gimple_code (gsi_stmt (si)) != GIMPLE_COND
3785 && gimple_code (gsi_stmt (si)) != GIMPLE_SWITCH);
3788 /* The new assertion A will be inserted at BB or E. We need to
3789 determine if the new location is dominated by a previously
3790 registered location for A. If we are doing an edge insertion,
3791 assume that A will be inserted at E->DEST. Note that this is not
3794 If E is a critical edge, it will be split. But even if E is
3795 split, the new block will dominate the same set of blocks that
3798 The reverse, however, is not true, blocks dominated by E->DEST
3799 will not be dominated by the new block created to split E. So,
3800 if the insertion location is on a critical edge, we will not use
3801 the new location to move another assertion previously registered
3802 at a block dominated by E->DEST. */
3803 dest_bb = (bb) ? bb : e->dest;
3805 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
3806 VAL at a block dominating DEST_BB, then we don't need to insert a new
3807 one. Similarly, if the same assertion already exists at a block
3808 dominated by DEST_BB and the new location is not on a critical
3809 edge, then update the existing location for the assertion (i.e.,
3810 move the assertion up in the dominance tree).
3812 Note, this is implemented as a simple linked list because there
3813 should not be more than a handful of assertions registered per
3814 name. If this becomes a performance problem, a table hashed by
3815 COMP_CODE and VAL could be implemented. */
3816 loc = asserts_for[SSA_NAME_VERSION (name)];
3821 if (loc->comp_code == comp_code
3823 || operand_equal_p (loc->val, val, 0))
3824 && (loc->expr == expr
3825 || operand_equal_p (loc->expr, expr, 0)))
3827 /* If the assertion NAME COMP_CODE VAL has already been
3828 registered at a basic block that dominates DEST_BB, then
3829 we don't need to insert the same assertion again. Note
3830 that we don't check strict dominance here to avoid
3831 replicating the same assertion inside the same basic
3832 block more than once (e.g., when a pointer is
3833 dereferenced several times inside a block).
3835 An exception to this rule are edge insertions. If the
3836 new assertion is to be inserted on edge E, then it will
3837 dominate all the other insertions that we may want to
3838 insert in DEST_BB. So, if we are doing an edge
3839 insertion, don't do this dominance check. */
3841 && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb))
3844 /* Otherwise, if E is not a critical edge and DEST_BB
3845 dominates the existing location for the assertion, move
3846 the assertion up in the dominance tree by updating its
3847 location information. */
3848 if ((e == NULL || !EDGE_CRITICAL_P (e))
3849 && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
3858 /* Update the last node of the list and move to the next one. */
3863 /* If we didn't find an assertion already registered for
3864 NAME COMP_CODE VAL, add a new one at the end of the list of
3865 assertions associated with NAME. */
3866 n = XNEW (struct assert_locus_d);
3870 n->comp_code = comp_code;
3878 asserts_for[SSA_NAME_VERSION (name)] = n;
3880 bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
3883 /* (COND_OP0 COND_CODE COND_OP1) is a predicate which uses NAME.
3884 Extract a suitable test code and value and store them into *CODE_P and
3885 *VAL_P so the predicate is normalized to NAME *CODE_P *VAL_P.
3887 If no extraction was possible, return FALSE, otherwise return TRUE.
3889 If INVERT is true, then we invert the result stored into *CODE_P. */
3892 extract_code_and_val_from_cond_with_ops (tree name, enum tree_code cond_code,
3893 tree cond_op0, tree cond_op1,
3894 bool invert, enum tree_code *code_p,
3897 enum tree_code comp_code;
3900 /* Otherwise, we have a comparison of the form NAME COMP VAL
3901 or VAL COMP NAME. */
3902 if (name == cond_op1)
3904 /* If the predicate is of the form VAL COMP NAME, flip
3905 COMP around because we need to register NAME as the
3906 first operand in the predicate. */
3907 comp_code = swap_tree_comparison (cond_code);
3912 /* The comparison is of the form NAME COMP VAL, so the
3913 comparison code remains unchanged. */
3914 comp_code = cond_code;
3918 /* Invert the comparison code as necessary. */
3920 comp_code = invert_tree_comparison (comp_code, 0);
3922 /* VRP does not handle float types. */
3923 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)))
3926 /* Do not register always-false predicates.
3927 FIXME: this works around a limitation in fold() when dealing with
3928 enumerations. Given 'enum { N1, N2 } x;', fold will not
3929 fold 'if (x > N2)' to 'if (0)'. */
3930 if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
3931 && INTEGRAL_TYPE_P (TREE_TYPE (val)))
3933 tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
3934 tree max = TYPE_MAX_VALUE (TREE_TYPE (val));
3936 if (comp_code == GT_EXPR
3938 || compare_values (val, max) == 0))
3941 if (comp_code == LT_EXPR
3943 || compare_values (val, min) == 0))
3946 *code_p = comp_code;
3951 /* Try to register an edge assertion for SSA name NAME on edge E for
3952 the condition COND contributing to the conditional jump pointed to by BSI.
3953 Invert the condition COND if INVERT is true.
3954 Return true if an assertion for NAME could be registered. */
3957 register_edge_assert_for_2 (tree name, edge e, gimple_stmt_iterator bsi,
3958 enum tree_code cond_code,
3959 tree cond_op0, tree cond_op1, bool invert)
3962 enum tree_code comp_code;
3963 bool retval = false;
3965 if (!extract_code_and_val_from_cond_with_ops (name, cond_code,
3968 invert, &comp_code, &val))
3971 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
3972 reachable from E. */
3973 if (live_on_edge (e, name)
3974 && !has_single_use (name))
3976 register_new_assert_for (name, name, comp_code, val, NULL, e, bsi);
3980 /* In the case of NAME <= CST and NAME being defined as
3981 NAME = (unsigned) NAME2 + CST2 we can assert NAME2 >= -CST2
3982 and NAME2 <= CST - CST2. We can do the same for NAME > CST.
3983 This catches range and anti-range tests. */
3984 if ((comp_code == LE_EXPR
3985 || comp_code == GT_EXPR)
3986 && TREE_CODE (val) == INTEGER_CST
3987 && TYPE_UNSIGNED (TREE_TYPE (val)))
3989 gimple def_stmt = SSA_NAME_DEF_STMT (name);
3990 tree cst2 = NULL_TREE, name2 = NULL_TREE, name3 = NULL_TREE;
3992 /* Extract CST2 from the (optional) addition. */
3993 if (is_gimple_assign (def_stmt)
3994 && gimple_assign_rhs_code (def_stmt) == PLUS_EXPR)
3996 name2 = gimple_assign_rhs1 (def_stmt);
3997 cst2 = gimple_assign_rhs2 (def_stmt);
3998 if (TREE_CODE (name2) == SSA_NAME
3999 && TREE_CODE (cst2) == INTEGER_CST)
4000 def_stmt = SSA_NAME_DEF_STMT (name2);
4003 /* Extract NAME2 from the (optional) sign-changing cast. */
4004 if (gimple_assign_cast_p (def_stmt))
4006 if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt))
4007 && ! TYPE_UNSIGNED (TREE_TYPE (gimple_assign_rhs1 (def_stmt)))
4008 && (TYPE_PRECISION (gimple_expr_type (def_stmt))
4009 == TYPE_PRECISION (TREE_TYPE (gimple_assign_rhs1 (def_stmt)))))
4010 name3 = gimple_assign_rhs1 (def_stmt);
4013 /* If name3 is used later, create an ASSERT_EXPR for it. */
4014 if (name3 != NULL_TREE
4015 && TREE_CODE (name3) == SSA_NAME
4016 && (cst2 == NULL_TREE
4017 || TREE_CODE (cst2) == INTEGER_CST)
4018 && INTEGRAL_TYPE_P (TREE_TYPE (name3))
4019 && live_on_edge (e, name3)
4020 && !has_single_use (name3))
4024 /* Build an expression for the range test. */
4025 tmp = build1 (NOP_EXPR, TREE_TYPE (name), name3);
4026 if (cst2 != NULL_TREE)
4027 tmp = build2 (PLUS_EXPR, TREE_TYPE (name), tmp, cst2);
4031 fprintf (dump_file, "Adding assert for ");
4032 print_generic_expr (dump_file, name3, 0);
4033 fprintf (dump_file, " from ");
4034 print_generic_expr (dump_file, tmp, 0);
4035 fprintf (dump_file, "\n");
4038 register_new_assert_for (name3, tmp, comp_code, val, NULL, e, bsi);
4043 /* If name2 is used later, create an ASSERT_EXPR for it. */
4044 if (name2 != NULL_TREE
4045 && TREE_CODE (name2) == SSA_NAME
4046 && TREE_CODE (cst2) == INTEGER_CST
4047 && INTEGRAL_TYPE_P (TREE_TYPE (name2))
4048 && live_on_edge (e, name2)
4049 && !has_single_use (name2))
4053 /* Build an expression for the range test. */
4055 if (TREE_TYPE (name) != TREE_TYPE (name2))
4056 tmp = build1 (NOP_EXPR, TREE_TYPE (name), tmp);
4057 if (cst2 != NULL_TREE)
4058 tmp = build2 (PLUS_EXPR, TREE_TYPE (name), tmp, cst2);
4062 fprintf (dump_file, "Adding assert for ");
4063 print_generic_expr (dump_file, name2, 0);
4064 fprintf (dump_file, " from ");
4065 print_generic_expr (dump_file, tmp, 0);
4066 fprintf (dump_file, "\n");
4069 register_new_assert_for (name2, tmp, comp_code, val, NULL, e, bsi);
4078 /* OP is an operand of a truth value expression which is known to have
4079 a particular value. Register any asserts for OP and for any
4080 operands in OP's defining statement.
4082 If CODE is EQ_EXPR, then we want to register OP is zero (false),
4083 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
4086 register_edge_assert_for_1 (tree op, enum tree_code code,
4087 edge e, gimple_stmt_iterator bsi)
4089 bool retval = false;
4092 enum tree_code rhs_code;
4094 /* We only care about SSA_NAMEs. */
4095 if (TREE_CODE (op) != SSA_NAME)
4098 /* We know that OP will have a zero or nonzero value. If OP is used
4099 more than once go ahead and register an assert for OP.
4101 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
4102 it will always be set for OP (because OP is used in a COND_EXPR in
4104 if (!has_single_use (op))
4106 val = build_int_cst (TREE_TYPE (op), 0);
4107 register_new_assert_for (op, op, code, val, NULL, e, bsi);
4111 /* Now look at how OP is set. If it's set from a comparison,
4112 a truth operation or some bit operations, then we may be able
4113 to register information about the operands of that assignment. */
4114 op_def = SSA_NAME_DEF_STMT (op);
4115 if (gimple_code (op_def) != GIMPLE_ASSIGN)
4118 rhs_code = gimple_assign_rhs_code (op_def);
4120 if (TREE_CODE_CLASS (rhs_code) == tcc_comparison)
4122 bool invert = (code == EQ_EXPR ? true : false);
4123 tree op0 = gimple_assign_rhs1 (op_def);
4124 tree op1 = gimple_assign_rhs2 (op_def);
4126 if (TREE_CODE (op0) == SSA_NAME)
4127 retval |= register_edge_assert_for_2 (op0, e, bsi, rhs_code, op0, op1,
4129 if (TREE_CODE (op1) == SSA_NAME)
4130 retval |= register_edge_assert_for_2 (op1, e, bsi, rhs_code, op0, op1,
4133 else if ((code == NE_EXPR
4134 && (gimple_assign_rhs_code (op_def) == TRUTH_AND_EXPR
4135 || gimple_assign_rhs_code (op_def) == BIT_AND_EXPR))
4137 && (gimple_assign_rhs_code (op_def) == TRUTH_OR_EXPR
4138 || gimple_assign_rhs_code (op_def) == BIT_IOR_EXPR)))
4140 /* Recurse on each operand. */
4141 retval |= register_edge_assert_for_1 (gimple_assign_rhs1 (op_def),
4143 retval |= register_edge_assert_for_1 (gimple_assign_rhs2 (op_def),
4146 else if (gimple_assign_rhs_code (op_def) == TRUTH_NOT_EXPR)
4148 /* Recurse, flipping CODE. */
4149 code = invert_tree_comparison (code, false);
4150 retval |= register_edge_assert_for_1 (gimple_assign_rhs1 (op_def),
4153 else if (gimple_assign_rhs_code (op_def) == SSA_NAME)
4155 /* Recurse through the copy. */
4156 retval |= register_edge_assert_for_1 (gimple_assign_rhs1 (op_def),
4159 else if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (op_def)))
4161 /* Recurse through the type conversion. */
4162 retval |= register_edge_assert_for_1 (gimple_assign_rhs1 (op_def),
4169 /* Try to register an edge assertion for SSA name NAME on edge E for
4170 the condition COND contributing to the conditional jump pointed to by SI.
4171 Return true if an assertion for NAME could be registered. */
4174 register_edge_assert_for (tree name, edge e, gimple_stmt_iterator si,
4175 enum tree_code cond_code, tree cond_op0,
4179 enum tree_code comp_code;
4180 bool retval = false;
4181 bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;
4183 /* Do not attempt to infer anything in names that flow through
4185 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
4188 if (!extract_code_and_val_from_cond_with_ops (name, cond_code,
4194 /* Register ASSERT_EXPRs for name. */
4195 retval |= register_edge_assert_for_2 (name, e, si, cond_code, cond_op0,
4196 cond_op1, is_else_edge);
4199 /* If COND is effectively an equality test of an SSA_NAME against
4200 the value zero or one, then we may be able to assert values
4201 for SSA_NAMEs which flow into COND. */
4203 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
4204 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
4205 have nonzero value. */
4206 if (((comp_code == EQ_EXPR && integer_onep (val))
4207 || (comp_code == NE_EXPR && integer_zerop (val))))
4209 gimple def_stmt = SSA_NAME_DEF_STMT (name);
4211 if (is_gimple_assign (def_stmt)
4212 && (gimple_assign_rhs_code (def_stmt) == TRUTH_AND_EXPR
4213 || gimple_assign_rhs_code (def_stmt) == BIT_AND_EXPR))
4215 tree op0 = gimple_assign_rhs1 (def_stmt);
4216 tree op1 = gimple_assign_rhs2 (def_stmt);
4217 retval |= register_edge_assert_for_1 (op0, NE_EXPR, e, si);
4218 retval |= register_edge_assert_for_1 (op1, NE_EXPR, e, si);
4222 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
4223 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
4225 if (((comp_code == EQ_EXPR && integer_zerop (val))
4226 || (comp_code == NE_EXPR && integer_onep (val))))
4228 gimple def_stmt = SSA_NAME_DEF_STMT (name);
4230 if (is_gimple_assign (def_stmt)
4231 && (gimple_assign_rhs_code (def_stmt) == TRUTH_OR_EXPR
4232 /* For BIT_IOR_EXPR only if NAME == 0 both operands have
4233 necessarily zero value. */
4234 || (comp_code == EQ_EXPR
4235 && (gimple_assign_rhs_code (def_stmt) == BIT_IOR_EXPR))))
4237 tree op0 = gimple_assign_rhs1 (def_stmt);
4238 tree op1 = gimple_assign_rhs2 (def_stmt);
4239 retval |= register_edge_assert_for_1 (op0, EQ_EXPR, e, si);
4240 retval |= register_edge_assert_for_1 (op1, EQ_EXPR, e, si);
4248 /* Determine whether the outgoing edges of BB should receive an
4249 ASSERT_EXPR for each of the operands of BB's LAST statement.
4250 The last statement of BB must be a COND_EXPR.
4252 If any of the sub-graphs rooted at BB have an interesting use of
4253 the predicate operands, an assert location node is added to the
4254 list of assertions for the corresponding operands. */
4257 find_conditional_asserts (basic_block bb, gimple last)
4260 gimple_stmt_iterator bsi;
4266 need_assert = false;
4267 bsi = gsi_for_stmt (last);
4269 /* Look for uses of the operands in each of the sub-graphs
4270 rooted at BB. We need to check each of the outgoing edges
4271 separately, so that we know what kind of ASSERT_EXPR to
4273 FOR_EACH_EDGE (e, ei, bb->succs)
4278 /* Register the necessary assertions for each operand in the
4279 conditional predicate. */
4280 FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
4282 need_assert |= register_edge_assert_for (op, e, bsi,
4283 gimple_cond_code (last),
4284 gimple_cond_lhs (last),
4285 gimple_cond_rhs (last));
4292 /* Compare two case labels sorting first by the destination label uid
4293 and then by the case value. */
4296 compare_case_labels (const void *p1, const void *p2)
4298 const_tree const case1 = *(const_tree const*)p1;
4299 const_tree const case2 = *(const_tree const*)p2;
4300 unsigned int uid1 = DECL_UID (CASE_LABEL (case1));
4301 unsigned int uid2 = DECL_UID (CASE_LABEL (case2));
4305 else if (uid1 == uid2)
4307 /* Make sure the default label is first in a group. */
4308 if (!CASE_LOW (case1))
4310 else if (!CASE_LOW (case2))
4313 return tree_int_cst_compare (CASE_LOW (case1), CASE_LOW (case2));
4319 /* Determine whether the outgoing edges of BB should receive an
4320 ASSERT_EXPR for each of the operands of BB's LAST statement.
4321 The last statement of BB must be a SWITCH_EXPR.
4323 If any of the sub-graphs rooted at BB have an interesting use of
4324 the predicate operands, an assert location node is added to the
4325 list of assertions for the corresponding operands. */
4328 find_switch_asserts (basic_block bb, gimple last)
4331 gimple_stmt_iterator bsi;
4335 size_t n = gimple_switch_num_labels(last);
4336 #if GCC_VERSION >= 4000
4339 /* Work around GCC 3.4 bug (PR 37086). */
4340 volatile unsigned int idx;
4343 need_assert = false;
4344 bsi = gsi_for_stmt (last);
4345 op = gimple_switch_index (last);
4346 if (TREE_CODE (op) != SSA_NAME)
4349 /* Build a vector of case labels sorted by destination label. */
4350 vec2 = make_tree_vec (n);
4351 for (idx = 0; idx < n; ++idx)
4352 TREE_VEC_ELT (vec2, idx) = gimple_switch_label (last, idx);
4353 qsort (&TREE_VEC_ELT (vec2, 0), n, sizeof (tree), compare_case_labels);
4355 for (idx = 0; idx < n; ++idx)
4358 tree cl = TREE_VEC_ELT (vec2, idx);
4360 min = CASE_LOW (cl);
4361 max = CASE_HIGH (cl);
4363 /* If there are multiple case labels with the same destination
4364 we need to combine them to a single value range for the edge. */
4366 && CASE_LABEL (cl) == CASE_LABEL (TREE_VEC_ELT (vec2, idx + 1)))
4368 /* Skip labels until the last of the group. */
4372 && CASE_LABEL (cl) == CASE_LABEL (TREE_VEC_ELT (vec2, idx)));
4375 /* Pick up the maximum of the case label range. */
4376 if (CASE_HIGH (TREE_VEC_ELT (vec2, idx)))
4377 max = CASE_HIGH (TREE_VEC_ELT (vec2, idx));
4379 max = CASE_LOW (TREE_VEC_ELT (vec2, idx));
4382 /* Nothing to do if the range includes the default label until we
4383 can register anti-ranges. */
4384 if (min == NULL_TREE)
4387 /* Find the edge to register the assert expr on. */
4388 e = find_edge (bb, label_to_block (CASE_LABEL (cl)));
4390 /* Register the necessary assertions for the operand in the
4392 need_assert |= register_edge_assert_for (op, e, bsi,
4393 max ? GE_EXPR : EQ_EXPR,
4395 fold_convert (TREE_TYPE (op),
4399 need_assert |= register_edge_assert_for (op, e, bsi, LE_EXPR,
4401 fold_convert (TREE_TYPE (op),
4410 /* Traverse all the statements in block BB looking for statements that
4411 may generate useful assertions for the SSA names in their operand.
4412 If a statement produces a useful assertion A for name N_i, then the
4413 list of assertions already generated for N_i is scanned to
4414 determine if A is actually needed.
4416 If N_i already had the assertion A at a location dominating the
4417 current location, then nothing needs to be done. Otherwise, the
4418 new location for A is recorded instead.
4420 1- For every statement S in BB, all the variables used by S are
4421 added to bitmap FOUND_IN_SUBGRAPH.
4423 2- If statement S uses an operand N in a way that exposes a known
4424 value range for N, then if N was not already generated by an
4425 ASSERT_EXPR, create a new assert location for N. For instance,
4426 if N is a pointer and the statement dereferences it, we can
4427 assume that N is not NULL.
4429 3- COND_EXPRs are a special case of #2. We can derive range
4430 information from the predicate but need to insert different
4431 ASSERT_EXPRs for each of the sub-graphs rooted at the
4432 conditional block. If the last statement of BB is a conditional
4433 expression of the form 'X op Y', then
4435 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
4437 b) If the conditional is the only entry point to the sub-graph
4438 corresponding to the THEN_CLAUSE, recurse into it. On
4439 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
4440 an ASSERT_EXPR is added for the corresponding variable.
4442 c) Repeat step (b) on the ELSE_CLAUSE.
4444 d) Mark X and Y in FOUND_IN_SUBGRAPH.
4453 In this case, an assertion on the THEN clause is useful to
4454 determine that 'a' is always 9 on that edge. However, an assertion
4455 on the ELSE clause would be unnecessary.
4457 4- If BB does not end in a conditional expression, then we recurse
4458 into BB's dominator children.
4460 At the end of the recursive traversal, every SSA name will have a
4461 list of locations where ASSERT_EXPRs should be added. When a new
4462 location for name N is found, it is registered by calling
4463 register_new_assert_for. That function keeps track of all the
4464 registered assertions to prevent adding unnecessary assertions.
4465 For instance, if a pointer P_4 is dereferenced more than once in a
4466 dominator tree, only the location dominating all the dereference of
4467 P_4 will receive an ASSERT_EXPR.
4469 If this function returns true, then it means that there are names
4470 for which we need to generate ASSERT_EXPRs. Those assertions are
4471 inserted by process_assert_insertions. */
4474 find_assert_locations_1 (basic_block bb, sbitmap live)
4476 gimple_stmt_iterator si;
4481 need_assert = false;
4482 last = last_stmt (bb);
4484 /* If BB's last statement is a conditional statement involving integer
4485 operands, determine if we need to add ASSERT_EXPRs. */
4487 && gimple_code (last) == GIMPLE_COND
4488 && !fp_predicate (last)
4489 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
4490 need_assert |= find_conditional_asserts (bb, last);
4492 /* If BB's last statement is a switch statement involving integer
4493 operands, determine if we need to add ASSERT_EXPRs. */
4495 && gimple_code (last) == GIMPLE_SWITCH
4496 && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
4497 need_assert |= find_switch_asserts (bb, last);
4499 /* Traverse all the statements in BB marking used names and looking
4500 for statements that may infer assertions for their used operands. */
4501 for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
4507 stmt = gsi_stmt (si);
4509 /* See if we can derive an assertion for any of STMT's operands. */
4510 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
4513 enum tree_code comp_code;
4515 /* Mark OP in our live bitmap. */
4516 SET_BIT (live, SSA_NAME_VERSION (op));
4518 /* If OP is used in such a way that we can infer a value
4519 range for it, and we don't find a previous assertion for
4520 it, create a new assertion location node for OP. */
4521 if (infer_value_range (stmt, op, &comp_code, &value))
4523 /* If we are able to infer a nonzero value range for OP,
4524 then walk backwards through the use-def chain to see if OP
4525 was set via a typecast.
4527 If so, then we can also infer a nonzero value range
4528 for the operand of the NOP_EXPR. */
4529 if (comp_code == NE_EXPR && integer_zerop (value))
4532 gimple def_stmt = SSA_NAME_DEF_STMT (t);
4534 while (is_gimple_assign (def_stmt)
4535 && gimple_assign_rhs_code (def_stmt) == NOP_EXPR
4537 (gimple_assign_rhs1 (def_stmt)) == SSA_NAME
4539 (TREE_TYPE (gimple_assign_rhs1 (def_stmt))))
4541 t = gimple_assign_rhs1 (def_stmt);
4542 def_stmt = SSA_NAME_DEF_STMT (t);
4544 /* Note we want to register the assert for the
4545 operand of the NOP_EXPR after SI, not after the
4547 if (! has_single_use (t))
4549 register_new_assert_for (t, t, comp_code, value,
4556 /* If OP is used only once, namely in this STMT, don't
4557 bother creating an ASSERT_EXPR for it. Such an
4558 ASSERT_EXPR would do nothing but increase compile time. */
4559 if (!has_single_use (op))
4561 register_new_assert_for (op, op, comp_code, value,
4569 /* Traverse all PHI nodes in BB marking used operands. */
4570 for (si = gsi_start_phis (bb); !gsi_end_p(si); gsi_next (&si))
4572 use_operand_p arg_p;
4574 phi = gsi_stmt (si);
4576 FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
4578 tree arg = USE_FROM_PTR (arg_p);
4579 if (TREE_CODE (arg) == SSA_NAME)
4580 SET_BIT (live, SSA_NAME_VERSION (arg));
4587 /* Do an RPO walk over the function computing SSA name liveness
4588 on-the-fly and deciding on assert expressions to insert.
4589 Returns true if there are assert expressions to be inserted. */
4592 find_assert_locations (void)
4594 int *rpo = XCNEWVEC (int, last_basic_block + NUM_FIXED_BLOCKS);
4595 int *bb_rpo = XCNEWVEC (int, last_basic_block + NUM_FIXED_BLOCKS);
4596 int *last_rpo = XCNEWVEC (int, last_basic_block + NUM_FIXED_BLOCKS);
4600 live = XCNEWVEC (sbitmap, last_basic_block + NUM_FIXED_BLOCKS);
4601 rpo_cnt = pre_and_rev_post_order_compute (NULL, rpo, false);
4602 for (i = 0; i < rpo_cnt; ++i)
4605 need_asserts = false;
4606 for (i = rpo_cnt-1; i >= 0; --i)
4608 basic_block bb = BASIC_BLOCK (rpo[i]);
4614 live[rpo[i]] = sbitmap_alloc (num_ssa_names);
4615 sbitmap_zero (live[rpo[i]]);
4618 /* Process BB and update the live information with uses in
4620 need_asserts |= find_assert_locations_1 (bb, live[rpo[i]]);
4622 /* Merge liveness into the predecessor blocks and free it. */
4623 if (!sbitmap_empty_p (live[rpo[i]]))
4626 FOR_EACH_EDGE (e, ei, bb->preds)
4628 int pred = e->src->index;
4629 if (e->flags & EDGE_DFS_BACK)
4634 live[pred] = sbitmap_alloc (num_ssa_names);
4635 sbitmap_zero (live[pred]);
4637 sbitmap_a_or_b (live[pred], live[pred], live[rpo[i]]);
4639 if (bb_rpo[pred] < pred_rpo)
4640 pred_rpo = bb_rpo[pred];
4643 /* Record the RPO number of the last visited block that needs
4644 live information from this block. */
4645 last_rpo[rpo[i]] = pred_rpo;
4649 sbitmap_free (live[rpo[i]]);
4650 live[rpo[i]] = NULL;
4653 /* We can free all successors live bitmaps if all their
4654 predecessors have been visited already. */
4655 FOR_EACH_EDGE (e, ei, bb->succs)
4656 if (last_rpo[e->dest->index] == i
4657 && live[e->dest->index])
4659 sbitmap_free (live[e->dest->index]);
4660 live[e->dest->index] = NULL;
4665 XDELETEVEC (bb_rpo);
4666 XDELETEVEC (last_rpo);
4667 for (i = 0; i < last_basic_block + NUM_FIXED_BLOCKS; ++i)
4669 sbitmap_free (live[i]);
4672 return need_asserts;
4675 /* Create an ASSERT_EXPR for NAME and insert it in the location
4676 indicated by LOC. Return true if we made any edge insertions. */
4679 process_assert_insertions_for (tree name, assert_locus_t loc)
4681 /* Build the comparison expression NAME_i COMP_CODE VAL. */
4688 cond = build2 (loc->comp_code, boolean_type_node, loc->expr, loc->val);
4689 assert_stmt = build_assert_expr_for (cond, name);
4692 /* We have been asked to insert the assertion on an edge. This
4693 is used only by COND_EXPR and SWITCH_EXPR assertions. */
4694 #if defined ENABLE_CHECKING
4695 gcc_assert (gimple_code (gsi_stmt (loc->si)) == GIMPLE_COND
4696 || gimple_code (gsi_stmt (loc->si)) == GIMPLE_SWITCH);
4699 gsi_insert_on_edge (loc->e, assert_stmt);
4703 /* Otherwise, we can insert right after LOC->SI iff the
4704 statement must not be the last statement in the block. */
4705 stmt = gsi_stmt (loc->si);
4706 if (!stmt_ends_bb_p (stmt))
4708 gsi_insert_after (&loc->si, assert_stmt, GSI_SAME_STMT);
4712 /* If STMT must be the last statement in BB, we can only insert new
4713 assertions on the non-abnormal edge out of BB. Note that since
4714 STMT is not control flow, there may only be one non-abnormal edge
4716 FOR_EACH_EDGE (e, ei, loc->bb->succs)
4717 if (!(e->flags & EDGE_ABNORMAL))
4719 gsi_insert_on_edge (e, assert_stmt);
4727 /* Process all the insertions registered for every name N_i registered
4728 in NEED_ASSERT_FOR. The list of assertions to be inserted are
4729 found in ASSERTS_FOR[i]. */
4732 process_assert_insertions (void)
4736 bool update_edges_p = false;
4737 int num_asserts = 0;
4739 if (dump_file && (dump_flags & TDF_DETAILS))
4740 dump_all_asserts (dump_file);
4742 EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
4744 assert_locus_t loc = asserts_for[i];
4749 assert_locus_t next = loc->next;
4750 update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
4758 gsi_commit_edge_inserts ();
4760 statistics_counter_event (cfun, "Number of ASSERT_EXPR expressions inserted",
4765 /* Traverse the flowgraph looking for conditional jumps to insert range
4766 expressions. These range expressions are meant to provide information
4767 to optimizations that need to reason in terms of value ranges. They
4768 will not be expanded into RTL. For instance, given:
4777 this pass will transform the code into:
4783 x = ASSERT_EXPR <x, x < y>
4788 y = ASSERT_EXPR <y, x <= y>
4792 The idea is that once copy and constant propagation have run, other
4793 optimizations will be able to determine what ranges of values can 'x'
4794 take in different paths of the code, simply by checking the reaching
4795 definition of 'x'. */
4798 insert_range_assertions (void)
4800 need_assert_for = BITMAP_ALLOC (NULL);
4801 asserts_for = XCNEWVEC (assert_locus_t, num_ssa_names);
4803 calculate_dominance_info (CDI_DOMINATORS);
4805 if (find_assert_locations ())
4807 process_assert_insertions ();
4808 update_ssa (TODO_update_ssa_no_phi);
4811 if (dump_file && (dump_flags & TDF_DETAILS))
4813 fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
4814 dump_function_to_file (current_function_decl, dump_file, dump_flags);
4818 BITMAP_FREE (need_assert_for);
4821 /* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays
4822 and "struct" hacks. If VRP can determine that the
4823 array subscript is a constant, check if it is outside valid
4824 range. If the array subscript is a RANGE, warn if it is
4825 non-overlapping with valid range.
4826 IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */
4829 check_array_ref (tree ref, const location_t *location, bool ignore_off_by_one)
4831 value_range_t* vr = NULL;
4832 tree low_sub, up_sub;
4833 tree low_bound, up_bound = array_ref_up_bound (ref);
4835 low_sub = up_sub = TREE_OPERAND (ref, 1);
4837 if (!up_bound || TREE_NO_WARNING (ref)
4838 || TREE_CODE (up_bound) != INTEGER_CST
4839 /* Can not check flexible arrays. */
4840 || (TYPE_SIZE (TREE_TYPE (ref)) == NULL_TREE
4841 && TYPE_DOMAIN (TREE_TYPE (ref)) != NULL_TREE
4842 && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (ref))) == NULL_TREE)
4843 /* Accesses after the end of arrays of size 0 (gcc
4844 extension) and 1 are likely intentional ("struct
4846 || compare_tree_int (up_bound, 1) <= 0)
4849 low_bound = array_ref_low_bound (ref);
4851 if (TREE_CODE (low_sub) == SSA_NAME)
4853 vr = get_value_range (low_sub);
4854 if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
4856 low_sub = vr->type == VR_RANGE ? vr->max : vr->min;
4857 up_sub = vr->type == VR_RANGE ? vr->min : vr->max;
4861 if (vr && vr->type == VR_ANTI_RANGE)
4863 if (TREE_CODE (up_sub) == INTEGER_CST
4864 && tree_int_cst_lt (up_bound, up_sub)
4865 && TREE_CODE (low_sub) == INTEGER_CST
4866 && tree_int_cst_lt (low_sub, low_bound))
4868 warning (OPT_Warray_bounds,
4869 "%Harray subscript is outside array bounds", location);
4870 TREE_NO_WARNING (ref) = 1;
4873 else if (TREE_CODE (up_sub) == INTEGER_CST
4874 && tree_int_cst_lt (up_bound, up_sub)
4875 && !tree_int_cst_equal (up_bound, up_sub)
4876 && (!ignore_off_by_one
4877 || !tree_int_cst_equal (int_const_binop (PLUS_EXPR,
4883 warning (OPT_Warray_bounds, "%Harray subscript is above array bounds",
4885 TREE_NO_WARNING (ref) = 1;
4887 else if (TREE_CODE (low_sub) == INTEGER_CST
4888 && tree_int_cst_lt (low_sub, low_bound))
4890 warning (OPT_Warray_bounds, "%Harray subscript is below array bounds",
4892 TREE_NO_WARNING (ref) = 1;
4896 /* Searches if the expr T, located at LOCATION computes
4897 address of an ARRAY_REF, and call check_array_ref on it. */
4900 search_for_addr_array(tree t, const location_t *location)
4902 while (TREE_CODE (t) == SSA_NAME)
4904 gimple g = SSA_NAME_DEF_STMT (t);
4906 if (gimple_code (g) != GIMPLE_ASSIGN)
4909 if (get_gimple_rhs_class (gimple_assign_rhs_code (g)) !=
4913 t = gimple_assign_rhs1 (g);
4917 /* We are only interested in addresses of ARRAY_REF's. */
4918 if (TREE_CODE (t) != ADDR_EXPR)
4921 /* Check each ARRAY_REFs in the reference chain. */
4924 if (TREE_CODE (t) == ARRAY_REF)
4925 check_array_ref (t, location, true /*ignore_off_by_one*/);
4927 t = TREE_OPERAND(t,0);
4929 while (handled_component_p (t));
4932 /* walk_tree() callback that checks if *TP is
4933 an ARRAY_REF inside an ADDR_EXPR (in which an array
4934 subscript one outside the valid range is allowed). Call
4935 check_array_ref for each ARRAY_REF found. The location is
4939 check_array_bounds (tree *tp, int *walk_subtree, void *data)
4942 struct walk_stmt_info *wi = (struct walk_stmt_info *) data;
4943 const location_t *location = (const location_t *) wi->info;
4945 *walk_subtree = TRUE;
4947 if (TREE_CODE (t) == ARRAY_REF)
4948 check_array_ref (t, location, false /*ignore_off_by_one*/);
4950 if (TREE_CODE (t) == INDIRECT_REF
4951 || (TREE_CODE (t) == RETURN_EXPR && TREE_OPERAND (t, 0)))
4952 search_for_addr_array (TREE_OPERAND (t, 0), location);
4954 if (TREE_CODE (t) == ADDR_EXPR)
4955 *walk_subtree = FALSE;
4960 /* Walk over all statements of all reachable BBs and call check_array_bounds
4964 check_all_array_refs (void)
4967 gimple_stmt_iterator si;
4971 /* Skip bb's that are clearly unreachable. */
4972 if (single_pred_p (bb))
4974 basic_block pred_bb = EDGE_PRED (bb, 0)->src;
4977 if (!gsi_end_p (gsi_last_bb (pred_bb)))
4978 ls = gsi_stmt (gsi_last_bb (pred_bb));
4980 if (ls && gimple_code (ls) == GIMPLE_COND
4981 && ((gimple_cond_false_p (ls)
4982 && (EDGE_PRED (bb, 0)->flags & EDGE_TRUE_VALUE))
4983 || (gimple_cond_true_p (ls)
4984 && (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE))))
4987 for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
4989 gimple stmt = gsi_stmt (si);
4990 const location_t *location = gimple_location_ptr (stmt);
4991 struct walk_stmt_info wi;
4992 if (!gimple_has_location (stmt))
4995 if (is_gimple_call (stmt))
4998 size_t n = gimple_call_num_args (stmt);
4999 for (i = 0; i < n; i++)
5001 tree arg = gimple_call_arg (stmt, i);
5002 search_for_addr_array (arg, location);
5007 memset (&wi, 0, sizeof (wi));
5008 wi.info = CONST_CAST (void *, (const void *) location);
5010 walk_gimple_op (gsi_stmt (si),
5018 /* Convert range assertion expressions into the implied copies and
5019 copy propagate away the copies. Doing the trivial copy propagation
5020 here avoids the need to run the full copy propagation pass after
5023 FIXME, this will eventually lead to copy propagation removing the
5024 names that had useful range information attached to them. For
5025 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
5026 then N_i will have the range [3, +INF].
5028 However, by converting the assertion into the implied copy
5029 operation N_i = N_j, we will then copy-propagate N_j into the uses
5030 of N_i and lose the range information. We may want to hold on to
5031 ASSERT_EXPRs a little while longer as the ranges could be used in
5032 things like jump threading.
5034 The problem with keeping ASSERT_EXPRs around is that passes after
5035 VRP need to handle them appropriately.
5037 Another approach would be to make the range information a first
5038 class property of the SSA_NAME so that it can be queried from
5039 any pass. This is made somewhat more complex by the need for
5040 multiple ranges to be associated with one SSA_NAME. */
5043 remove_range_assertions (void)
5046 gimple_stmt_iterator si;
5048 /* Note that the BSI iterator bump happens at the bottom of the
5049 loop and no bump is necessary if we're removing the statement
5050 referenced by the current BSI. */
5052 for (si = gsi_start_bb (bb); !gsi_end_p (si);)
5054 gimple stmt = gsi_stmt (si);
5057 if (is_gimple_assign (stmt)
5058 && gimple_assign_rhs_code (stmt) == ASSERT_EXPR)
5060 tree rhs = gimple_assign_rhs1 (stmt);
5062 tree cond = fold (ASSERT_EXPR_COND (rhs));
5063 use_operand_p use_p;
5064 imm_use_iterator iter;
5066 gcc_assert (cond != boolean_false_node);
5068 /* Propagate the RHS into every use of the LHS. */
5069 var = ASSERT_EXPR_VAR (rhs);
5070 FOR_EACH_IMM_USE_STMT (use_stmt, iter,
5071 gimple_assign_lhs (stmt))
5072 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
5074 SET_USE (use_p, var);
5075 gcc_assert (TREE_CODE (var) == SSA_NAME);
5078 /* And finally, remove the copy, it is not needed. */
5079 gsi_remove (&si, true);
5080 release_defs (stmt);
5088 /* Return true if STMT is interesting for VRP. */
5091 stmt_interesting_for_vrp (gimple stmt)
5093 if (gimple_code (stmt) == GIMPLE_PHI
5094 && is_gimple_reg (gimple_phi_result (stmt))
5095 && (INTEGRAL_TYPE_P (TREE_TYPE (gimple_phi_result (stmt)))
5096 || POINTER_TYPE_P (TREE_TYPE (gimple_phi_result (stmt)))))
5098 else if (is_gimple_assign (stmt) || is_gimple_call (stmt))
5100 tree lhs = gimple_get_lhs (stmt);
5102 /* In general, assignments with virtual operands are not useful
5103 for deriving ranges, with the obvious exception of calls to
5104 builtin functions. */
5105 if (lhs && TREE_CODE (lhs) == SSA_NAME
5106 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
5107 || POINTER_TYPE_P (TREE_TYPE (lhs)))
5108 && ((is_gimple_call (stmt)
5109 && gimple_call_fndecl (stmt) != NULL_TREE
5110 && DECL_IS_BUILTIN (gimple_call_fndecl (stmt)))
5111 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)))
5114 else if (gimple_code (stmt) == GIMPLE_COND
5115 || gimple_code (stmt) == GIMPLE_SWITCH)
5122 /* Initialize local data structures for VRP. */
5125 vrp_initialize (void)
5129 vr_value = XCNEWVEC (value_range_t *, num_ssa_names);
5130 vr_phi_edge_counts = XCNEWVEC (int, num_ssa_names);
5134 gimple_stmt_iterator si;
5136 for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
5138 gimple phi = gsi_stmt (si);
5139 if (!stmt_interesting_for_vrp (phi))
5141 tree lhs = PHI_RESULT (phi);
5142 set_value_range_to_varying (get_value_range (lhs));
5143 prop_set_simulate_again (phi, false);
5146 prop_set_simulate_again (phi, true);
5149 for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
5151 gimple stmt = gsi_stmt (si);
5153 if (!stmt_interesting_for_vrp (stmt))
5157 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
5158 set_value_range_to_varying (get_value_range (def));
5159 prop_set_simulate_again (stmt, false);
5163 prop_set_simulate_again (stmt, true);
5170 /* Visit assignment STMT. If it produces an interesting range, record
5171 the SSA name in *OUTPUT_P. */
5173 static enum ssa_prop_result
5174 vrp_visit_assignment_or_call (gimple stmt, tree *output_p)
5178 enum gimple_code code = gimple_code (stmt);
5179 lhs = gimple_get_lhs (stmt);
5181 /* We only keep track of ranges in integral and pointer types. */
5182 if (TREE_CODE (lhs) == SSA_NAME
5183 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
5184 /* It is valid to have NULL MIN/MAX values on a type. See
5185 build_range_type. */
5186 && TYPE_MIN_VALUE (TREE_TYPE (lhs))
5187 && TYPE_MAX_VALUE (TREE_TYPE (lhs)))
5188 || POINTER_TYPE_P (TREE_TYPE (lhs))))
5191 value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
5193 if (code == GIMPLE_CALL)
5194 extract_range_basic (&new_vr, stmt);
5196 extract_range_from_assignment (&new_vr, stmt);
5198 /* If STMT is inside a loop, we may be able to know something
5199 else about the range of LHS by examining scalar evolution
5201 if (current_loops && (l = loop_containing_stmt (stmt)))
5202 adjust_range_with_scev (&new_vr, l, stmt, lhs);
5204 if (update_value_range (lhs, &new_vr))
5208 if (dump_file && (dump_flags & TDF_DETAILS))
5210 fprintf (dump_file, "Found new range for ");
5211 print_generic_expr (dump_file, lhs, 0);
5212 fprintf (dump_file, ": ");
5213 dump_value_range (dump_file, &new_vr);
5214 fprintf (dump_file, "\n\n");
5217 if (new_vr.type == VR_VARYING)
5218 return SSA_PROP_VARYING;
5220 return SSA_PROP_INTERESTING;
5223 return SSA_PROP_NOT_INTERESTING;
5226 /* Every other statement produces no useful ranges. */
5227 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
5228 set_value_range_to_varying (get_value_range (def));
5230 return SSA_PROP_VARYING;
5233 /* Helper that gets the value range of the SSA_NAME with version I
5234 or a symbolic range containing the SSA_NAME only if the value range
5235 is varying or undefined. */
5237 static inline value_range_t
5238 get_vr_for_comparison (int i)
5240 value_range_t vr = *(vr_value[i]);
5242 /* If name N_i does not have a valid range, use N_i as its own
5243 range. This allows us to compare against names that may
5244 have N_i in their ranges. */
5245 if (vr.type == VR_VARYING || vr.type == VR_UNDEFINED)
5248 vr.min = ssa_name (i);
5249 vr.max = ssa_name (i);
5255 /* Compare all the value ranges for names equivalent to VAR with VAL
5256 using comparison code COMP. Return the same value returned by
5257 compare_range_with_value, including the setting of
5258 *STRICT_OVERFLOW_P. */
5261 compare_name_with_value (enum tree_code comp, tree var, tree val,
5262 bool *strict_overflow_p)
5268 int used_strict_overflow;
5270 value_range_t equiv_vr;
5272 /* Get the set of equivalences for VAR. */
5273 e = get_value_range (var)->equiv;
5275 /* Start at -1. Set it to 0 if we do a comparison without relying
5276 on overflow, or 1 if all comparisons rely on overflow. */
5277 used_strict_overflow = -1;
5279 /* Compare vars' value range with val. */
5280 equiv_vr = get_vr_for_comparison (SSA_NAME_VERSION (var));
5282 retval = compare_range_with_value (comp, &equiv_vr, val, &sop);
5284 used_strict_overflow = sop ? 1 : 0;
5286 /* If the equiv set is empty we have done all work we need to do. */
5290 && used_strict_overflow > 0)
5291 *strict_overflow_p = true;
5295 EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
5297 equiv_vr = get_vr_for_comparison (i);
5299 t = compare_range_with_value (comp, &equiv_vr, val, &sop);
5302 /* If we get different answers from different members
5303 of the equivalence set this check must be in a dead
5304 code region. Folding it to a trap representation
5305 would be correct here. For now just return don't-know. */
5315 used_strict_overflow = 0;
5316 else if (used_strict_overflow < 0)
5317 used_strict_overflow = 1;
5322 && used_strict_overflow > 0)
5323 *strict_overflow_p = true;
5329 /* Given a comparison code COMP and names N1 and N2, compare all the
5330 ranges equivalent to N1 against all the ranges equivalent to N2
5331 to determine the value of N1 COMP N2. Return the same value
5332 returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate
5333 whether we relied on an overflow infinity in the comparison. */
5337 compare_names (enum tree_code comp, tree n1, tree n2,
5338 bool *strict_overflow_p)
5342 bitmap_iterator bi1, bi2;
5344 int used_strict_overflow;
5345 static bitmap_obstack *s_obstack = NULL;
5346 static bitmap s_e1 = NULL, s_e2 = NULL;
5348 /* Compare the ranges of every name equivalent to N1 against the
5349 ranges of every name equivalent to N2. */
5350 e1 = get_value_range (n1)->equiv;
5351 e2 = get_value_range (n2)->equiv;
5353 /* Use the fake bitmaps if e1 or e2 are not available. */
5354 if (s_obstack == NULL)
5356 s_obstack = XNEW (bitmap_obstack);
5357 bitmap_obstack_initialize (s_obstack);
5358 s_e1 = BITMAP_ALLOC (s_obstack);
5359 s_e2 = BITMAP_ALLOC (s_obstack);
5366 /* Add N1 and N2 to their own set of equivalences to avoid
5367 duplicating the body of the loop just to check N1 and N2
5369 bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
5370 bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
5372 /* If the equivalence sets have a common intersection, then the two
5373 names can be compared without checking their ranges. */
5374 if (bitmap_intersect_p (e1, e2))
5376 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
5377 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
5379 return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
5381 : boolean_false_node;
5384 /* Start at -1. Set it to 0 if we do a comparison without relying
5385 on overflow, or 1 if all comparisons rely on overflow. */
5386 used_strict_overflow = -1;
5388 /* Otherwise, compare all the equivalent ranges. First, add N1 and
5389 N2 to their own set of equivalences to avoid duplicating the body
5390 of the loop just to check N1 and N2 ranges. */
5391 EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
5393 value_range_t vr1 = get_vr_for_comparison (i1);
5395 t = retval = NULL_TREE;
5396 EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
5400 value_range_t vr2 = get_vr_for_comparison (i2);
5402 t = compare_ranges (comp, &vr1, &vr2, &sop);
5405 /* If we get different answers from different members
5406 of the equivalence set this check must be in a dead
5407 code region. Folding it to a trap representation
5408 would be correct here. For now just return don't-know. */
5412 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
5413 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
5419 used_strict_overflow = 0;
5420 else if (used_strict_overflow < 0)
5421 used_strict_overflow = 1;
5427 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
5428 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
5429 if (used_strict_overflow > 0)
5430 *strict_overflow_p = true;
5435 /* None of the equivalent ranges are useful in computing this
5437 bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
5438 bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
5442 /* Helper function for vrp_evaluate_conditional_warnv. */
5445 vrp_evaluate_conditional_warnv_with_ops (enum tree_code code, tree op0,
5446 tree op1, bool use_equiv_p,
5447 bool *strict_overflow_p)
5449 /* We only deal with integral and pointer types. */
5450 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
5451 && !POINTER_TYPE_P (TREE_TYPE (op0)))
5456 if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
5457 return compare_names (code, op0, op1, strict_overflow_p);
5458 else if (TREE_CODE (op0) == SSA_NAME)
5459 return compare_name_with_value (code, op0, op1, strict_overflow_p);
5460 else if (TREE_CODE (op1) == SSA_NAME)
5461 return (compare_name_with_value
5462 (swap_tree_comparison (code), op1, op0, strict_overflow_p));
5466 value_range_t *vr0, *vr1;
5468 vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL;
5469 vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL;
5472 return compare_ranges (code, vr0, vr1, strict_overflow_p);
5473 else if (vr0 && vr1 == NULL)
5474 return compare_range_with_value (code, vr0, op1, strict_overflow_p);
5475 else if (vr0 == NULL && vr1)
5476 return (compare_range_with_value
5477 (swap_tree_comparison (code), vr1, op0, strict_overflow_p));
5482 /* Given (CODE OP0 OP1) within STMT, try to simplify it based on value range
5483 information. Return NULL if the conditional can not be evaluated.
5484 The ranges of all the names equivalent with the operands in COND
5485 will be used when trying to compute the value. If the result is
5486 based on undefined signed overflow, issue a warning if
5490 vrp_evaluate_conditional (enum tree_code code, tree op0, tree op1, gimple stmt)
5496 ret = vrp_evaluate_conditional_warnv_with_ops (code, op0, op1, true, &sop);
5500 enum warn_strict_overflow_code wc;
5501 const char* warnmsg;
5503 if (is_gimple_min_invariant (ret))
5505 wc = WARN_STRICT_OVERFLOW_CONDITIONAL;
5506 warnmsg = G_("assuming signed overflow does not occur when "
5507 "simplifying conditional to constant");
5511 wc = WARN_STRICT_OVERFLOW_COMPARISON;
5512 warnmsg = G_("assuming signed overflow does not occur when "
5513 "simplifying conditional");
5516 if (issue_strict_overflow_warning (wc))
5518 location_t location;
5520 if (!gimple_has_location (stmt))
5521 location = input_location;
5523 location = gimple_location (stmt);
5524 warning (OPT_Wstrict_overflow, "%H%s", &location, warnmsg);
5528 if (warn_type_limits
5530 && TREE_CODE_CLASS (code) == tcc_comparison
5531 && TREE_CODE (op0) == SSA_NAME)
5533 /* If the comparison is being folded and the operand on the LHS
5534 is being compared against a constant value that is outside of
5535 the natural range of OP0's type, then the predicate will
5536 always fold regardless of the value of OP0. If -Wtype-limits
5537 was specified, emit a warning. */
5538 const char *warnmsg = NULL;
5539 tree type = TREE_TYPE (op0);
5540 value_range_t *vr0 = get_value_range (op0);
5542 if (vr0->type != VR_VARYING
5543 && INTEGRAL_TYPE_P (type)
5544 && vrp_val_is_min (vr0->min)
5545 && vrp_val_is_max (vr0->max)
5546 && is_gimple_min_invariant (op1))
5548 if (integer_zerop (ret))
5549 warnmsg = G_("comparison always false due to limited range of "
5552 warnmsg = G_("comparison always true due to limited range of "
5558 location_t location;
5560 if (!gimple_has_location (stmt))
5561 location = input_location;
5563 location = gimple_location (stmt);
5565 warning (OPT_Wtype_limits, "%H%s", &location, warnmsg);
5573 /* Visit conditional statement STMT. If we can determine which edge
5574 will be taken out of STMT's basic block, record it in
5575 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
5576 SSA_PROP_VARYING. */
5578 static enum ssa_prop_result
5579 vrp_visit_cond_stmt (gimple stmt, edge *taken_edge_p)
5584 *taken_edge_p = NULL;
5586 if (dump_file && (dump_flags & TDF_DETAILS))
5591 fprintf (dump_file, "\nVisiting conditional with predicate: ");
5592 print_gimple_stmt (dump_file, stmt, 0, 0);
5593 fprintf (dump_file, "\nWith known ranges\n");
5595 FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
5597 fprintf (dump_file, "\t");
5598 print_generic_expr (dump_file, use, 0);
5599 fprintf (dump_file, ": ");
5600 dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]);
5603 fprintf (dump_file, "\n");
5606 /* Compute the value of the predicate COND by checking the known
5607 ranges of each of its operands.
5609 Note that we cannot evaluate all the equivalent ranges here
5610 because those ranges may not yet be final and with the current
5611 propagation strategy, we cannot determine when the value ranges
5612 of the names in the equivalence set have changed.
5614 For instance, given the following code fragment
5618 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
5622 Assume that on the first visit to i_14, i_5 has the temporary
5623 range [8, 8] because the second argument to the PHI function is
5624 not yet executable. We derive the range ~[0, 0] for i_14 and the
5625 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
5626 the first time, since i_14 is equivalent to the range [8, 8], we
5627 determine that the predicate is always false.
5629 On the next round of propagation, i_13 is determined to be
5630 VARYING, which causes i_5 to drop down to VARYING. So, another
5631 visit to i_14 is scheduled. In this second visit, we compute the
5632 exact same range and equivalence set for i_14, namely ~[0, 0] and
5633 { i_5 }. But we did not have the previous range for i_5
5634 registered, so vrp_visit_assignment thinks that the range for
5635 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
5636 is not visited again, which stops propagation from visiting
5637 statements in the THEN clause of that if().
5639 To properly fix this we would need to keep the previous range
5640 value for the names in the equivalence set. This way we would've
5641 discovered that from one visit to the other i_5 changed from
5642 range [8, 8] to VR_VARYING.
5644 However, fixing this apparent limitation may not be worth the
5645 additional checking. Testing on several code bases (GCC, DLV,
5646 MICO, TRAMP3D and SPEC2000) showed that doing this results in
5647 4 more predicates folded in SPEC. */
5650 val = vrp_evaluate_conditional_warnv_with_ops (gimple_cond_code (stmt),
5651 gimple_cond_lhs (stmt),
5652 gimple_cond_rhs (stmt),
5657 *taken_edge_p = find_taken_edge (gimple_bb (stmt), val);
5660 if (dump_file && (dump_flags & TDF_DETAILS))
5662 "\nIgnoring predicate evaluation because "
5663 "it assumes that signed overflow is undefined");
5668 if (dump_file && (dump_flags & TDF_DETAILS))
5670 fprintf (dump_file, "\nPredicate evaluates to: ");
5671 if (val == NULL_TREE)
5672 fprintf (dump_file, "DON'T KNOW\n");
5674 print_generic_stmt (dump_file, val, 0);
5677 return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
5680 /* Searches the case label vector VEC for the index *IDX of the CASE_LABEL
5681 that includes the value VAL. The search is restricted to the range
5682 [START_IDX, n - 1] where n is the size of VEC.
5684 If there is a CASE_LABEL for VAL, its index is placed in IDX and true is
5687 If there is no CASE_LABEL for VAL and the is one that is larger than VAL,
5688 it is placed in IDX and false is returned.
5690 If VAL is larger than any CASE_LABEL, n is placed on IDX and false is
5694 find_case_label_index (gimple stmt, size_t start_idx, tree val, size_t *idx)
5696 size_t n = gimple_switch_num_labels (stmt);
5699 /* Find case label for minimum of the value range or the next one.
5700 At each iteration we are searching in [low, high - 1]. */
5702 for (low = start_idx, high = n; high != low; )
5706 /* Note that i != high, so we never ask for n. */
5707 size_t i = (high + low) / 2;
5708 t = gimple_switch_label (stmt, i);
5710 /* Cache the result of comparing CASE_LOW and val. */
5711 cmp = tree_int_cst_compare (CASE_LOW (t), val);
5715 /* Ranges cannot be empty. */
5724 if (CASE_HIGH (t) != NULL
5725 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
5737 /* Searches the case label vector VEC for the range of CASE_LABELs that is used
5738 for values between MIN and MAX. The first index is placed in MIN_IDX. The
5739 last index is placed in MAX_IDX. If the range of CASE_LABELs is empty
5740 then MAX_IDX < MIN_IDX.
5741 Returns true if the default label is not needed. */
5744 find_case_label_range (gimple stmt, tree min, tree max, size_t *min_idx,
5748 bool min_take_default = !find_case_label_index (stmt, 1, min, &i);
5749 bool max_take_default = !find_case_label_index (stmt, i, max, &j);
5753 && max_take_default)
5755 /* Only the default case label reached.
5756 Return an empty range. */
5763 bool take_default = min_take_default || max_take_default;
5767 if (max_take_default)
5770 /* If the case label range is continuous, we do not need
5771 the default case label. Verify that. */
5772 high = CASE_LOW (gimple_switch_label (stmt, i));
5773 if (CASE_HIGH (gimple_switch_label (stmt, i)))
5774 high = CASE_HIGH (gimple_switch_label (stmt, i));
5775 for (k = i + 1; k <= j; ++k)
5777 low = CASE_LOW (gimple_switch_label (stmt, k));
5778 if (!integer_onep (int_const_binop (MINUS_EXPR, low, high, 0)))
5780 take_default = true;
5784 if (CASE_HIGH (gimple_switch_label (stmt, k)))
5785 high = CASE_HIGH (gimple_switch_label (stmt, k));
5790 return !take_default;
5794 /* Visit switch statement STMT. If we can determine which edge
5795 will be taken out of STMT's basic block, record it in
5796 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
5797 SSA_PROP_VARYING. */
5799 static enum ssa_prop_result
5800 vrp_visit_switch_stmt (gimple stmt, edge *taken_edge_p)
5804 size_t i = 0, j = 0, n;
5807 *taken_edge_p = NULL;
5808 op = gimple_switch_index (stmt);
5809 if (TREE_CODE (op) != SSA_NAME)
5810 return SSA_PROP_VARYING;
5812 vr = get_value_range (op);
5813 if (dump_file && (dump_flags & TDF_DETAILS))
5815 fprintf (dump_file, "\nVisiting switch expression with operand ");
5816 print_generic_expr (dump_file, op, 0);
5817 fprintf (dump_file, " with known range ");
5818 dump_value_range (dump_file, vr);
5819 fprintf (dump_file, "\n");
5822 if (vr->type != VR_RANGE
5823 || symbolic_range_p (vr))
5824 return SSA_PROP_VARYING;
5826 /* Find the single edge that is taken from the switch expression. */
5827 n = gimple_switch_num_labels (stmt);
5829 take_default = !find_case_label_range (stmt, vr->min, vr->max, &i, &j);
5831 /* Check if the range spans no CASE_LABEL. If so, we only reach the default
5835 gcc_assert (take_default);
5836 val = gimple_switch_default_label (stmt);
5840 /* Check if labels with index i to j and maybe the default label
5841 are all reaching the same label. */
5843 val = gimple_switch_label (stmt, i);
5845 && CASE_LABEL (gimple_switch_default_label (stmt))
5846 != CASE_LABEL (val))
5848 if (dump_file && (dump_flags & TDF_DETAILS))
5849 fprintf (dump_file, " not a single destination for this "
5851 return SSA_PROP_VARYING;
5853 for (++i; i <= j; ++i)
5855 if (CASE_LABEL (gimple_switch_label (stmt, i)) != CASE_LABEL (val))
5857 if (dump_file && (dump_flags & TDF_DETAILS))
5858 fprintf (dump_file, " not a single destination for this "
5860 return SSA_PROP_VARYING;
5865 *taken_edge_p = find_edge (gimple_bb (stmt),
5866 label_to_block (CASE_LABEL (val)));
5868 if (dump_file && (dump_flags & TDF_DETAILS))
5870 fprintf (dump_file, " will take edge to ");
5871 print_generic_stmt (dump_file, CASE_LABEL (val), 0);
5874 return SSA_PROP_INTERESTING;
5878 /* Evaluate statement STMT. If the statement produces a useful range,
5879 return SSA_PROP_INTERESTING and record the SSA name with the
5880 interesting range into *OUTPUT_P.
5882 If STMT is a conditional branch and we can determine its truth
5883 value, the taken edge is recorded in *TAKEN_EDGE_P.
5885 If STMT produces a varying value, return SSA_PROP_VARYING. */
5887 static enum ssa_prop_result
5888 vrp_visit_stmt (gimple stmt, edge *taken_edge_p, tree *output_p)
5893 if (dump_file && (dump_flags & TDF_DETAILS))
5895 fprintf (dump_file, "\nVisiting statement:\n");
5896 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
5897 fprintf (dump_file, "\n");
5900 if (is_gimple_assign (stmt) || is_gimple_call (stmt))
5902 /* In general, assignments with virtual operands are not useful
5903 for deriving ranges, with the obvious exception of calls to
5904 builtin functions. */
5906 if ((is_gimple_call (stmt)
5907 && gimple_call_fndecl (stmt) != NULL_TREE
5908 && DECL_IS_BUILTIN (gimple_call_fndecl (stmt)))
5909 || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
5910 return vrp_visit_assignment_or_call (stmt, output_p);
5912 else if (gimple_code (stmt) == GIMPLE_COND)
5913 return vrp_visit_cond_stmt (stmt, taken_edge_p);
5914 else if (gimple_code (stmt) == GIMPLE_SWITCH)
5915 return vrp_visit_switch_stmt (stmt, taken_edge_p);
5917 /* All other statements produce nothing of interest for VRP, so mark
5918 their outputs varying and prevent further simulation. */
5919 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
5920 set_value_range_to_varying (get_value_range (def));
5922 return SSA_PROP_VARYING;
5926 /* Meet operation for value ranges. Given two value ranges VR0 and
5927 VR1, store in VR0 a range that contains both VR0 and VR1. This
5928 may not be the smallest possible such range. */
5931 vrp_meet (value_range_t *vr0, value_range_t *vr1)
5933 if (vr0->type == VR_UNDEFINED)
5935 copy_value_range (vr0, vr1);
5939 if (vr1->type == VR_UNDEFINED)
5941 /* Nothing to do. VR0 already has the resulting range. */
5945 if (vr0->type == VR_VARYING)
5947 /* Nothing to do. VR0 already has the resulting range. */
5951 if (vr1->type == VR_VARYING)
5953 set_value_range_to_varying (vr0);
5957 if (vr0->type == VR_RANGE && vr1->type == VR_RANGE)
5962 /* Compute the convex hull of the ranges. The lower limit of
5963 the new range is the minimum of the two ranges. If they
5964 cannot be compared, then give up. */
5965 cmp = compare_values (vr0->min, vr1->min);
5966 if (cmp == 0 || cmp == 1)
5973 /* Similarly, the upper limit of the new range is the maximum
5974 of the two ranges. If they cannot be compared, then
5976 cmp = compare_values (vr0->max, vr1->max);
5977 if (cmp == 0 || cmp == -1)
5984 /* Check for useless ranges. */
5985 if (INTEGRAL_TYPE_P (TREE_TYPE (min))
5986 && ((vrp_val_is_min (min) || is_overflow_infinity (min))
5987 && (vrp_val_is_max (max) || is_overflow_infinity (max))))
5990 /* The resulting set of equivalences is the intersection of
5992 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
5993 bitmap_and_into (vr0->equiv, vr1->equiv);
5994 else if (vr0->equiv && !vr1->equiv)
5995 bitmap_clear (vr0->equiv);
5997 set_value_range (vr0, vr0->type, min, max, vr0->equiv);
5999 else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE)
6001 /* Two anti-ranges meet only if their complements intersect.
6002 Only handle the case of identical ranges. */
6003 if (compare_values (vr0->min, vr1->min) == 0
6004 && compare_values (vr0->max, vr1->max) == 0
6005 && compare_values (vr0->min, vr0->max) == 0)
6007 /* The resulting set of equivalences is the intersection of
6009 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
6010 bitmap_and_into (vr0->equiv, vr1->equiv);
6011 else if (vr0->equiv && !vr1->equiv)
6012 bitmap_clear (vr0->equiv);
6017 else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE)
6019 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
6020 only handle the case where the ranges have an empty intersection.
6021 The result of the meet operation is the anti-range. */
6022 if (!symbolic_range_p (vr0)
6023 && !symbolic_range_p (vr1)
6024 && !value_ranges_intersect_p (vr0, vr1))
6026 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
6027 set. We need to compute the intersection of the two
6028 equivalence sets. */
6029 if (vr1->type == VR_ANTI_RANGE)
6030 set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
6032 /* The resulting set of equivalences is the intersection of
6034 if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
6035 bitmap_and_into (vr0->equiv, vr1->equiv);
6036 else if (vr0->equiv && !vr1->equiv)
6037 bitmap_clear (vr0->equiv);
6048 /* Failed to find an efficient meet. Before giving up and setting
6049 the result to VARYING, see if we can at least derive a useful
6050 anti-range. FIXME, all this nonsense about distinguishing
6051 anti-ranges from ranges is necessary because of the odd
6052 semantics of range_includes_zero_p and friends. */
6053 if (!symbolic_range_p (vr0)
6054 && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0))
6055 || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0)))
6056 && !symbolic_range_p (vr1)
6057 && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1))
6058 || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1))))
6060 set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min));
6062 /* Since this meet operation did not result from the meeting of
6063 two equivalent names, VR0 cannot have any equivalences. */
6065 bitmap_clear (vr0->equiv);
6068 set_value_range_to_varying (vr0);
6072 /* Visit all arguments for PHI node PHI that flow through executable
6073 edges. If a valid value range can be derived from all the incoming
6074 value ranges, set a new range for the LHS of PHI. */
6076 static enum ssa_prop_result
6077 vrp_visit_phi_node (gimple phi)
6080 tree lhs = PHI_RESULT (phi);
6081 value_range_t *lhs_vr = get_value_range (lhs);
6082 value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
6083 int edges, old_edges;
6085 copy_value_range (&vr_result, lhs_vr);
6087 if (dump_file && (dump_flags & TDF_DETAILS))
6089 fprintf (dump_file, "\nVisiting PHI node: ");
6090 print_gimple_stmt (dump_file, phi, 0, dump_flags);
6094 for (i = 0; i < gimple_phi_num_args (phi); i++)
6096 edge e = gimple_phi_arg_edge (phi, i);
6098 if (dump_file && (dump_flags & TDF_DETAILS))
6101 "\n Argument #%d (%d -> %d %sexecutable)\n",
6102 (int) i, e->src->index, e->dest->index,
6103 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
6106 if (e->flags & EDGE_EXECUTABLE)
6108 tree arg = PHI_ARG_DEF (phi, i);
6109 value_range_t vr_arg;
6113 if (TREE_CODE (arg) == SSA_NAME)
6115 vr_arg = *(get_value_range (arg));
6119 if (is_overflow_infinity (arg))
6121 arg = copy_node (arg);
6122 TREE_OVERFLOW (arg) = 0;
6125 vr_arg.type = VR_RANGE;
6128 vr_arg.equiv = NULL;
6131 if (dump_file && (dump_flags & TDF_DETAILS))
6133 fprintf (dump_file, "\t");
6134 print_generic_expr (dump_file, arg, dump_flags);
6135 fprintf (dump_file, "\n\tValue: ");
6136 dump_value_range (dump_file, &vr_arg);
6137 fprintf (dump_file, "\n");
6140 vrp_meet (&vr_result, &vr_arg);
6142 if (vr_result.type == VR_VARYING)
6147 if (vr_result.type == VR_VARYING)
6150 old_edges = vr_phi_edge_counts[SSA_NAME_VERSION (lhs)];
6151 vr_phi_edge_counts[SSA_NAME_VERSION (lhs)] = edges;
6153 /* To prevent infinite iterations in the algorithm, derive ranges
6154 when the new value is slightly bigger or smaller than the
6155 previous one. We don't do this if we have seen a new executable
6156 edge; this helps us avoid an overflow infinity for conditionals
6157 which are not in a loop. */
6158 if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE
6159 && edges <= old_edges)
6161 if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
6163 int cmp_min = compare_values (lhs_vr->min, vr_result.min);
6164 int cmp_max = compare_values (lhs_vr->max, vr_result.max);
6166 /* If the new minimum is smaller or larger than the previous
6167 one, go all the way to -INF. In the first case, to avoid
6168 iterating millions of times to reach -INF, and in the
6169 other case to avoid infinite bouncing between different
6171 if (cmp_min > 0 || cmp_min < 0)
6173 /* If we will end up with a (-INF, +INF) range, set it
6175 if (vrp_val_is_max (vr_result.max))
6178 if (!needs_overflow_infinity (TREE_TYPE (vr_result.min))
6179 || !vrp_var_may_overflow (lhs, phi))
6180 vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min));
6181 else if (supports_overflow_infinity (TREE_TYPE (vr_result.min)))
6183 negative_overflow_infinity (TREE_TYPE (vr_result.min));
6188 /* Similarly, if the new maximum is smaller or larger than
6189 the previous one, go all the way to +INF. */
6190 if (cmp_max < 0 || cmp_max > 0)
6192 /* If we will end up with a (-INF, +INF) range, set it
6194 if (vrp_val_is_min (vr_result.min))
6197 if (!needs_overflow_infinity (TREE_TYPE (vr_result.max))
6198 || !vrp_var_may_overflow (lhs, phi))
6199 vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max));
6200 else if (supports_overflow_infinity (TREE_TYPE (vr_result.max)))
6202 positive_overflow_infinity (TREE_TYPE (vr_result.max));
6209 /* If the new range is different than the previous value, keep
6211 if (update_value_range (lhs, &vr_result))
6212 return SSA_PROP_INTERESTING;
6214 /* Nothing changed, don't add outgoing edges. */
6215 return SSA_PROP_NOT_INTERESTING;
6217 /* No match found. Set the LHS to VARYING. */
6219 set_value_range_to_varying (lhs_vr);
6220 return SSA_PROP_VARYING;
6223 /* Simplify a division or modulo operator to a right shift or
6224 bitwise and if the first operand is unsigned or is greater
6225 than zero and the second operand is an exact power of two. */
6228 simplify_div_or_mod_using_ranges (gimple stmt)
6230 enum tree_code rhs_code = gimple_assign_rhs_code (stmt);
6232 tree op0 = gimple_assign_rhs1 (stmt);
6233 tree op1 = gimple_assign_rhs2 (stmt);
6234 value_range_t *vr = get_value_range (gimple_assign_rhs1 (stmt));
6236 if (TYPE_UNSIGNED (TREE_TYPE (op0)))
6238 val = integer_one_node;
6244 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node, &sop);
6248 && integer_onep (val)
6249 && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
6251 location_t location;
6253 if (!gimple_has_location (stmt))
6254 location = input_location;
6256 location = gimple_location (stmt);
6257 warning (OPT_Wstrict_overflow,
6258 ("%Hassuming signed overflow does not occur when "
6259 "simplifying / or %% to >> or &"),
6264 if (val && integer_onep (val))
6268 if (rhs_code == TRUNC_DIV_EXPR)
6270 t = build_int_cst (NULL_TREE, tree_log2 (op1));
6271 gimple_assign_set_rhs_code (stmt, RSHIFT_EXPR);
6272 gimple_assign_set_rhs1 (stmt, op0);
6273 gimple_assign_set_rhs2 (stmt, t);
6277 t = build_int_cst (TREE_TYPE (op1), 1);
6278 t = int_const_binop (MINUS_EXPR, op1, t, 0);
6279 t = fold_convert (TREE_TYPE (op0), t);
6281 gimple_assign_set_rhs_code (stmt, BIT_AND_EXPR);
6282 gimple_assign_set_rhs1 (stmt, op0);
6283 gimple_assign_set_rhs2 (stmt, t);
6290 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
6291 ABS_EXPR. If the operand is <= 0, then simplify the
6292 ABS_EXPR into a NEGATE_EXPR. */
6295 simplify_abs_using_ranges (gimple stmt)
6298 tree op = gimple_assign_rhs1 (stmt);
6299 tree type = TREE_TYPE (op);
6300 value_range_t *vr = get_value_range (op);
6302 if (TYPE_UNSIGNED (type))
6304 val = integer_zero_node;
6310 val = compare_range_with_value (LE_EXPR, vr, integer_zero_node, &sop);
6314 val = compare_range_with_value (GE_EXPR, vr, integer_zero_node,
6319 if (integer_zerop (val))
6320 val = integer_one_node;
6321 else if (integer_onep (val))
6322 val = integer_zero_node;
6327 && (integer_onep (val) || integer_zerop (val)))
6329 if (sop && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC))
6331 location_t location;
6333 if (!gimple_has_location (stmt))
6334 location = input_location;
6336 location = gimple_location (stmt);
6337 warning (OPT_Wstrict_overflow,
6338 ("%Hassuming signed overflow does not occur when "
6339 "simplifying abs (X) to X or -X"),
6343 gimple_assign_set_rhs1 (stmt, op);
6344 if (integer_onep (val))
6345 gimple_assign_set_rhs_code (stmt, NEGATE_EXPR);
6347 gimple_assign_set_rhs_code (stmt, SSA_NAME);
6353 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
6354 a known value range VR.
6356 If there is one and only one value which will satisfy the
6357 conditional, then return that value. Else return NULL. */
6360 test_for_singularity (enum tree_code cond_code, tree op0,
6361 tree op1, value_range_t *vr)
6366 /* Extract minimum/maximum values which satisfy the
6367 the conditional as it was written. */
6368 if (cond_code == LE_EXPR || cond_code == LT_EXPR)
6370 /* This should not be negative infinity; there is no overflow
6372 min = TYPE_MIN_VALUE (TREE_TYPE (op0));
6375 if (cond_code == LT_EXPR && !is_overflow_infinity (max))
6377 tree one = build_int_cst (TREE_TYPE (op0), 1);
6378 max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one);
6380 TREE_NO_WARNING (max) = 1;
6383 else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
6385 /* This should not be positive infinity; there is no overflow
6387 max = TYPE_MAX_VALUE (TREE_TYPE (op0));
6390 if (cond_code == GT_EXPR && !is_overflow_infinity (min))
6392 tree one = build_int_cst (TREE_TYPE (op0), 1);
6393 min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one);
6395 TREE_NO_WARNING (min) = 1;
6399 /* Now refine the minimum and maximum values using any
6400 value range information we have for op0. */
6403 if (compare_values (vr->min, min) == -1)
6407 if (compare_values (vr->max, max) == 1)
6412 /* If the new min/max values have converged to a single value,
6413 then there is only one value which can satisfy the condition,
6414 return that value. */
6415 if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min))
6421 /* Simplify a conditional using a relational operator to an equality
6422 test if the range information indicates only one value can satisfy
6423 the original conditional. */
6426 simplify_cond_using_ranges (gimple stmt)
6428 tree op0 = gimple_cond_lhs (stmt);
6429 tree op1 = gimple_cond_rhs (stmt);
6430 enum tree_code cond_code = gimple_cond_code (stmt);
6432 if (cond_code != NE_EXPR
6433 && cond_code != EQ_EXPR
6434 && TREE_CODE (op0) == SSA_NAME
6435 && INTEGRAL_TYPE_P (TREE_TYPE (op0))
6436 && is_gimple_min_invariant (op1))
6438 value_range_t *vr = get_value_range (op0);
6440 /* If we have range information for OP0, then we might be
6441 able to simplify this conditional. */
6442 if (vr->type == VR_RANGE)
6444 tree new_tree = test_for_singularity (cond_code, op0, op1, vr);
6450 fprintf (dump_file, "Simplified relational ");
6451 print_gimple_stmt (dump_file, stmt, 0, 0);
6452 fprintf (dump_file, " into ");
6455 gimple_cond_set_code (stmt, EQ_EXPR);
6456 gimple_cond_set_lhs (stmt, op0);
6457 gimple_cond_set_rhs (stmt, new_tree);
6463 print_gimple_stmt (dump_file, stmt, 0, 0);
6464 fprintf (dump_file, "\n");
6470 /* Try again after inverting the condition. We only deal
6471 with integral types here, so no need to worry about
6472 issues with inverting FP comparisons. */
6473 cond_code = invert_tree_comparison (cond_code, false);
6474 new_tree = test_for_singularity (cond_code, op0, op1, vr);
6480 fprintf (dump_file, "Simplified relational ");
6481 print_gimple_stmt (dump_file, stmt, 0, 0);
6482 fprintf (dump_file, " into ");
6485 gimple_cond_set_code (stmt, NE_EXPR);
6486 gimple_cond_set_lhs (stmt, op0);
6487 gimple_cond_set_rhs (stmt, new_tree);
6493 print_gimple_stmt (dump_file, stmt, 0, 0);
6494 fprintf (dump_file, "\n");
6503 /* Simplify a switch statement using the value range of the switch
6507 simplify_switch_using_ranges (gimple stmt)
6509 tree op = gimple_switch_index (stmt);
6514 size_t i = 0, j = 0, n, n2;
6518 if (TREE_CODE (op) != SSA_NAME)
6521 vr = get_value_range (op);
6523 /* We can only handle integer ranges. */
6524 if (vr->type != VR_RANGE
6525 || symbolic_range_p (vr))
6528 /* Find case label for min/max of the value range. */
6529 n = gimple_switch_num_labels (stmt);
6530 take_default = !find_case_label_range (stmt, vr->min, vr->max, &i, &j);
6532 /* Bail out if this is just all edges taken. */
6538 /* Build a new vector of taken case labels. */
6539 vec2 = make_tree_vec (j - i + 1 + (int)take_default);
6542 /* Add the default edge, if necessary. */
6544 TREE_VEC_ELT (vec2, n2++) = gimple_switch_default_label (stmt);
6546 for (; i <= j; ++i, ++n2)
6547 TREE_VEC_ELT (vec2, n2) = gimple_switch_label (stmt, i);
6549 /* Mark needed edges. */
6550 for (i = 0; i < n2; ++i)
6552 e = find_edge (gimple_bb (stmt),
6553 label_to_block (CASE_LABEL (TREE_VEC_ELT (vec2, i))));
6554 e->aux = (void *)-1;
6557 /* Queue not needed edges for later removal. */
6558 FOR_EACH_EDGE (e, ei, gimple_bb (stmt)->succs)
6560 if (e->aux == (void *)-1)
6566 if (dump_file && (dump_flags & TDF_DETAILS))
6568 fprintf (dump_file, "removing unreachable case label\n");
6570 VEC_safe_push (edge, heap, to_remove_edges, e);
6573 /* And queue an update for the stmt. */
6576 VEC_safe_push (switch_update, heap, to_update_switch_stmts, &su);
6579 /* Simplify STMT using ranges if possible. */
6582 simplify_stmt_using_ranges (gimple stmt)
6584 if (is_gimple_assign (stmt))
6586 enum tree_code rhs_code = gimple_assign_rhs_code (stmt);
6588 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
6589 and BIT_AND_EXPR respectively if the first operand is greater
6590 than zero and the second operand is an exact power of two. */
6591 if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR)
6592 && INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (stmt)))
6593 && integer_pow2p (gimple_assign_rhs2 (stmt)))
6594 simplify_div_or_mod_using_ranges (stmt);
6596 /* Transform ABS (X) into X or -X as appropriate. */
6597 if (rhs_code == ABS_EXPR
6598 && TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
6599 && INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (stmt))))
6600 simplify_abs_using_ranges (stmt);
6602 else if (gimple_code (stmt) == GIMPLE_COND)
6603 simplify_cond_using_ranges (stmt);
6604 else if (gimple_code (stmt) == GIMPLE_SWITCH)
6605 simplify_switch_using_ranges (stmt);
6608 /* Stack of dest,src equivalency pairs that need to be restored after
6609 each attempt to thread a block's incoming edge to an outgoing edge.
6611 A NULL entry is used to mark the end of pairs which need to be
6613 static VEC(tree,heap) *stack;
6615 /* A trivial wrapper so that we can present the generic jump threading
6616 code with a simple API for simplifying statements. STMT is the
6617 statement we want to simplify, WITHIN_STMT provides the location
6618 for any overflow warnings. */
6621 simplify_stmt_for_jump_threading (gimple stmt, gimple within_stmt)
6623 /* We only use VRP information to simplify conditionals. This is
6624 overly conservative, but it's unclear if doing more would be
6625 worth the compile time cost. */
6626 if (gimple_code (stmt) != GIMPLE_COND)
6629 return vrp_evaluate_conditional (gimple_cond_code (stmt),
6630 gimple_cond_lhs (stmt),
6631 gimple_cond_rhs (stmt), within_stmt);
6634 /* Blocks which have more than one predecessor and more than
6635 one successor present jump threading opportunities, i.e.,
6636 when the block is reached from a specific predecessor, we
6637 may be able to determine which of the outgoing edges will
6638 be traversed. When this optimization applies, we are able
6639 to avoid conditionals at runtime and we may expose secondary
6640 optimization opportunities.
6642 This routine is effectively a driver for the generic jump
6643 threading code. It basically just presents the generic code
6644 with edges that may be suitable for jump threading.
6646 Unlike DOM, we do not iterate VRP if jump threading was successful.
6647 While iterating may expose new opportunities for VRP, it is expected
6648 those opportunities would be very limited and the compile time cost
6649 to expose those opportunities would be significant.
6651 As jump threading opportunities are discovered, they are registered
6652 for later realization. */
6655 identify_jump_threads (void)
6662 /* Ugh. When substituting values earlier in this pass we can
6663 wipe the dominance information. So rebuild the dominator
6664 information as we need it within the jump threading code. */
6665 calculate_dominance_info (CDI_DOMINATORS);
6667 /* We do not allow VRP information to be used for jump threading
6668 across a back edge in the CFG. Otherwise it becomes too
6669 difficult to avoid eliminating loop exit tests. Of course
6670 EDGE_DFS_BACK is not accurate at this time so we have to
6672 mark_dfs_back_edges ();
6674 /* Do not thread across edges we are about to remove. Just marking
6675 them as EDGE_DFS_BACK will do. */
6676 for (i = 0; VEC_iterate (edge, to_remove_edges, i, e); ++i)
6677 e->flags |= EDGE_DFS_BACK;
6679 /* Allocate our unwinder stack to unwind any temporary equivalences
6680 that might be recorded. */
6681 stack = VEC_alloc (tree, heap, 20);
6683 /* To avoid lots of silly node creation, we create a single
6684 conditional and just modify it in-place when attempting to
6686 dummy = gimple_build_cond (EQ_EXPR,
6687 integer_zero_node, integer_zero_node,
6690 /* Walk through all the blocks finding those which present a
6691 potential jump threading opportunity. We could set this up
6692 as a dominator walker and record data during the walk, but
6693 I doubt it's worth the effort for the classes of jump
6694 threading opportunities we are trying to identify at this
6695 point in compilation. */
6700 /* If the generic jump threading code does not find this block
6701 interesting, then there is nothing to do. */
6702 if (! potentially_threadable_block (bb))
6705 /* We only care about blocks ending in a COND_EXPR. While there
6706 may be some value in handling SWITCH_EXPR here, I doubt it's
6707 terribly important. */
6708 last = gsi_stmt (gsi_last_bb (bb));
6709 if (gimple_code (last) != GIMPLE_COND)
6712 /* We're basically looking for any kind of conditional with
6713 integral type arguments. */
6714 if (TREE_CODE (gimple_cond_lhs (last)) == SSA_NAME
6715 && INTEGRAL_TYPE_P (TREE_TYPE (gimple_cond_lhs (last)))
6716 && (TREE_CODE (gimple_cond_rhs (last)) == SSA_NAME
6717 || is_gimple_min_invariant (gimple_cond_rhs (last)))
6718 && INTEGRAL_TYPE_P (TREE_TYPE (gimple_cond_rhs (last))))
6722 /* We've got a block with multiple predecessors and multiple
6723 successors which also ends in a suitable conditional. For
6724 each predecessor, see if we can thread it to a specific
6726 FOR_EACH_EDGE (e, ei, bb->preds)
6728 /* Do not thread across back edges or abnormal edges
6730 if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
6733 thread_across_edge (dummy, e, true, &stack,
6734 simplify_stmt_for_jump_threading);
6739 /* We do not actually update the CFG or SSA graphs at this point as
6740 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
6741 handle ASSERT_EXPRs gracefully. */
6744 /* We identified all the jump threading opportunities earlier, but could
6745 not transform the CFG at that time. This routine transforms the
6746 CFG and arranges for the dominator tree to be rebuilt if necessary.
6748 Note the SSA graph update will occur during the normal TODO
6749 processing by the pass manager. */
6751 finalize_jump_threads (void)
6753 thread_through_all_blocks (false);
6754 VEC_free (tree, heap, stack);
6758 /* Traverse all the blocks folding conditionals with known ranges. */
6764 prop_value_t *single_val_range;
6765 bool do_value_subst_p;
6769 fprintf (dump_file, "\nValue ranges after VRP:\n\n");
6770 dump_all_value_ranges (dump_file);
6771 fprintf (dump_file, "\n");
6774 /* We may have ended with ranges that have exactly one value. Those
6775 values can be substituted as any other copy/const propagated
6776 value using substitute_and_fold. */
6777 single_val_range = XCNEWVEC (prop_value_t, num_ssa_names);
6779 do_value_subst_p = false;
6780 for (i = 0; i < num_ssa_names; i++)
6782 && vr_value[i]->type == VR_RANGE
6783 && vr_value[i]->min == vr_value[i]->max)
6785 single_val_range[i].value = vr_value[i]->min;
6786 do_value_subst_p = true;
6789 if (!do_value_subst_p)
6791 /* We found no single-valued ranges, don't waste time trying to
6792 do single value substitution in substitute_and_fold. */
6793 free (single_val_range);
6794 single_val_range = NULL;
6797 substitute_and_fold (single_val_range, true);
6799 if (warn_array_bounds)
6800 check_all_array_refs ();
6802 /* We must identify jump threading opportunities before we release
6803 the datastructures built by VRP. */
6804 identify_jump_threads ();
6806 /* Free allocated memory. */
6807 for (i = 0; i < num_ssa_names; i++)
6810 BITMAP_FREE (vr_value[i]->equiv);
6814 free (single_val_range);
6816 free (vr_phi_edge_counts);
6818 /* So that we can distinguish between VRP data being available
6819 and not available. */
6821 vr_phi_edge_counts = NULL;
6825 /* Main entry point to VRP (Value Range Propagation). This pass is
6826 loosely based on J. R. C. Patterson, ``Accurate Static Branch
6827 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
6828 Programming Language Design and Implementation, pp. 67-78, 1995.
6829 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
6831 This is essentially an SSA-CCP pass modified to deal with ranges
6832 instead of constants.
6834 While propagating ranges, we may find that two or more SSA name
6835 have equivalent, though distinct ranges. For instance,
6838 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
6840 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
6844 In the code above, pointer p_5 has range [q_2, q_2], but from the
6845 code we can also determine that p_5 cannot be NULL and, if q_2 had
6846 a non-varying range, p_5's range should also be compatible with it.
6848 These equivalences are created by two expressions: ASSERT_EXPR and
6849 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
6850 result of another assertion, then we can use the fact that p_5 and
6851 p_4 are equivalent when evaluating p_5's range.
6853 Together with value ranges, we also propagate these equivalences
6854 between names so that we can take advantage of information from
6855 multiple ranges when doing final replacement. Note that this
6856 equivalency relation is transitive but not symmetric.
6858 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
6859 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
6860 in contexts where that assertion does not hold (e.g., in line 6).
6862 TODO, the main difference between this pass and Patterson's is that
6863 we do not propagate edge probabilities. We only compute whether
6864 edges can be taken or not. That is, instead of having a spectrum
6865 of jump probabilities between 0 and 1, we only deal with 0, 1 and
6866 DON'T KNOW. In the future, it may be worthwhile to propagate
6867 probabilities to aid branch prediction. */
6876 loop_optimizer_init (LOOPS_NORMAL | LOOPS_HAVE_RECORDED_EXITS);
6877 rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa);
6880 insert_range_assertions ();
6882 to_remove_edges = VEC_alloc (edge, heap, 10);
6883 to_update_switch_stmts = VEC_alloc (switch_update, heap, 5);
6886 ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
6889 /* ASSERT_EXPRs must be removed before finalizing jump threads
6890 as finalizing jump threads calls the CFG cleanup code which
6891 does not properly handle ASSERT_EXPRs. */
6892 remove_range_assertions ();
6894 /* If we exposed any new variables, go ahead and put them into
6895 SSA form now, before we handle jump threading. This simplifies
6896 interactions between rewriting of _DECL nodes into SSA form
6897 and rewriting SSA_NAME nodes into SSA form after block
6898 duplication and CFG manipulation. */
6899 update_ssa (TODO_update_ssa);
6901 finalize_jump_threads ();
6903 /* Remove dead edges from SWITCH_EXPR optimization. This leaves the
6904 CFG in a broken state and requires a cfg_cleanup run. */
6905 for (i = 0; VEC_iterate (edge, to_remove_edges, i, e); ++i)
6907 /* Update SWITCH_EXPR case label vector. */
6908 for (i = 0; VEC_iterate (switch_update, to_update_switch_stmts, i, su); ++i)
6911 size_t n = TREE_VEC_LENGTH (su->vec);
6912 gimple_switch_set_num_labels (su->stmt, n);
6913 for (j = 0; j < n; j++)
6914 gimple_switch_set_label (su->stmt, j, TREE_VEC_ELT (su->vec, j));
6917 if (VEC_length (edge, to_remove_edges) > 0)
6918 free_dominance_info (CDI_DOMINATORS);
6920 VEC_free (edge, heap, to_remove_edges);
6921 VEC_free (switch_update, heap, to_update_switch_stmts);
6924 loop_optimizer_finalize ();
6931 return flag_tree_vrp != 0;
6934 struct gimple_opt_pass pass_vrp =
6939 gate_vrp, /* gate */
6940 execute_vrp, /* execute */
6943 0, /* static_pass_number */
6944 TV_TREE_VRP, /* tv_id */
6945 PROP_ssa | PROP_alias, /* properties_required */
6946 0, /* properties_provided */
6947 0, /* properties_destroyed */
6948 0, /* todo_flags_start */
6953 | TODO_update_ssa /* todo_flags_finish */