1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 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"
41 /* Set of SSA names found during the dominator traversal of a
42 sub-graph in find_assert_locations. */
43 static sbitmap found_in_subgraph
;
45 /* Local functions. */
46 static int compare_values (tree val1
, tree val2
);
47 static int compare_values_warnv (tree val1
, tree val2
, bool *);
48 static void vrp_meet (value_range_t
*, value_range_t
*);
49 static tree
vrp_evaluate_conditional_warnv_with_ops (enum tree_code
,
50 tree
, tree
, bool, bool *);
52 /* Location information for ASSERT_EXPRs. Each instance of this
53 structure describes an ASSERT_EXPR for an SSA name. Since a single
54 SSA name may have more than one assertion associated with it, these
55 locations are kept in a linked list attached to the corresponding
59 /* Basic block where the assertion would be inserted. */
62 /* Some assertions need to be inserted on an edge (e.g., assertions
63 generated by COND_EXPRs). In those cases, BB will be NULL. */
66 /* Pointer to the statement that generated this assertion. */
67 block_stmt_iterator si
;
69 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
70 enum tree_code comp_code
;
72 /* Value being compared against. */
75 /* Expression to compare. */
78 /* Next node in the linked list. */
79 struct assert_locus_d
*next
;
82 typedef struct assert_locus_d
*assert_locus_t
;
84 /* If bit I is present, it means that SSA name N_i has a list of
85 assertions that should be inserted in the IL. */
86 static bitmap need_assert_for
;
88 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
89 holds a list of ASSERT_LOCUS_T nodes that describe where
90 ASSERT_EXPRs for SSA name N_I should be inserted. */
91 static assert_locus_t
*asserts_for
;
93 /* Set of blocks visited in find_assert_locations. Used to avoid
94 visiting the same block more than once. */
95 static sbitmap blocks_visited
;
97 /* Value range array. After propagation, VR_VALUE[I] holds the range
98 of values that SSA name N_I may take. */
99 static value_range_t
**vr_value
;
101 /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the
102 number of executable edges we saw the last time we visited the
104 static int *vr_phi_edge_counts
;
111 static VEC (edge
, heap
) *to_remove_edges
;
112 DEF_VEC_O(switch_update
);
113 DEF_VEC_ALLOC_O(switch_update
, heap
);
114 static VEC (switch_update
, heap
) *to_update_switch_stmts
;
117 /* Return the maximum value for TYPEs base type. */
120 vrp_val_max (const_tree type
)
122 if (!INTEGRAL_TYPE_P (type
))
125 /* For integer sub-types the values for the base type are relevant. */
126 if (TREE_TYPE (type
))
127 type
= TREE_TYPE (type
);
129 return TYPE_MAX_VALUE (type
);
132 /* Return the minimum value for TYPEs base type. */
135 vrp_val_min (const_tree type
)
137 if (!INTEGRAL_TYPE_P (type
))
140 /* For integer sub-types the values for the base type are relevant. */
141 if (TREE_TYPE (type
))
142 type
= TREE_TYPE (type
);
144 return TYPE_MIN_VALUE (type
);
147 /* Return whether VAL is equal to the maximum value of its type. This
148 will be true for a positive overflow infinity. We can't do a
149 simple equality comparison with TYPE_MAX_VALUE because C typedefs
150 and Ada subtypes can produce types whose TYPE_MAX_VALUE is not ==
151 to the integer constant with the same value in the type. */
154 vrp_val_is_max (const_tree val
)
156 tree type_max
= vrp_val_max (TREE_TYPE (val
));
157 return (val
== type_max
158 || (type_max
!= NULL_TREE
159 && operand_equal_p (val
, type_max
, 0)));
162 /* Return whether VAL is equal to the minimum value of its type. This
163 will be true for a negative overflow infinity. */
166 vrp_val_is_min (const_tree val
)
168 tree type_min
= vrp_val_min (TREE_TYPE (val
));
169 return (val
== type_min
170 || (type_min
!= NULL_TREE
171 && operand_equal_p (val
, type_min
, 0)));
175 /* Return whether TYPE should use an overflow infinity distinct from
176 TYPE_{MIN,MAX}_VALUE. We use an overflow infinity value to
177 represent a signed overflow during VRP computations. An infinity
178 is distinct from a half-range, which will go from some number to
179 TYPE_{MIN,MAX}_VALUE. */
182 needs_overflow_infinity (const_tree type
)
184 return (INTEGRAL_TYPE_P (type
)
185 && !TYPE_OVERFLOW_WRAPS (type
)
186 /* Integer sub-types never overflow as they are never
187 operands of arithmetic operators. */
188 && !(TREE_TYPE (type
) && TREE_TYPE (type
) != type
));
191 /* Return whether TYPE can support our overflow infinity
192 representation: we use the TREE_OVERFLOW flag, which only exists
193 for constants. If TYPE doesn't support this, we don't optimize
194 cases which would require signed overflow--we drop them to
198 supports_overflow_infinity (const_tree type
)
200 tree min
= vrp_val_min (type
), max
= vrp_val_max (type
);
201 #ifdef ENABLE_CHECKING
202 gcc_assert (needs_overflow_infinity (type
));
204 return (min
!= NULL_TREE
205 && CONSTANT_CLASS_P (min
)
207 && CONSTANT_CLASS_P (max
));
210 /* VAL is the maximum or minimum value of a type. Return a
211 corresponding overflow infinity. */
214 make_overflow_infinity (tree val
)
216 #ifdef ENABLE_CHECKING
217 gcc_assert (val
!= NULL_TREE
&& CONSTANT_CLASS_P (val
));
219 val
= copy_node (val
);
220 TREE_OVERFLOW (val
) = 1;
224 /* Return a negative overflow infinity for TYPE. */
227 negative_overflow_infinity (tree type
)
229 #ifdef ENABLE_CHECKING
230 gcc_assert (supports_overflow_infinity (type
));
232 return make_overflow_infinity (vrp_val_min (type
));
235 /* Return a positive overflow infinity for TYPE. */
238 positive_overflow_infinity (tree type
)
240 #ifdef ENABLE_CHECKING
241 gcc_assert (supports_overflow_infinity (type
));
243 return make_overflow_infinity (vrp_val_max (type
));
246 /* Return whether VAL is a negative overflow infinity. */
249 is_negative_overflow_infinity (const_tree val
)
251 return (needs_overflow_infinity (TREE_TYPE (val
))
252 && CONSTANT_CLASS_P (val
)
253 && TREE_OVERFLOW (val
)
254 && vrp_val_is_min (val
));
257 /* Return whether VAL is a positive overflow infinity. */
260 is_positive_overflow_infinity (const_tree val
)
262 return (needs_overflow_infinity (TREE_TYPE (val
))
263 && CONSTANT_CLASS_P (val
)
264 && TREE_OVERFLOW (val
)
265 && vrp_val_is_max (val
));
268 /* Return whether VAL is a positive or negative overflow infinity. */
271 is_overflow_infinity (const_tree val
)
273 return (needs_overflow_infinity (TREE_TYPE (val
))
274 && CONSTANT_CLASS_P (val
)
275 && TREE_OVERFLOW (val
)
276 && (vrp_val_is_min (val
) || vrp_val_is_max (val
)));
279 /* If VAL is now an overflow infinity, return VAL. Otherwise, return
280 the same value with TREE_OVERFLOW clear. This can be used to avoid
281 confusing a regular value with an overflow value. */
284 avoid_overflow_infinity (tree val
)
286 if (!is_overflow_infinity (val
))
289 if (vrp_val_is_max (val
))
290 return vrp_val_max (TREE_TYPE (val
));
293 #ifdef ENABLE_CHECKING
294 gcc_assert (vrp_val_is_min (val
));
296 return vrp_val_min (TREE_TYPE (val
));
301 /* Return true if ARG is marked with the nonnull attribute in the
302 current function signature. */
305 nonnull_arg_p (const_tree arg
)
307 tree t
, attrs
, fntype
;
308 unsigned HOST_WIDE_INT arg_num
;
310 gcc_assert (TREE_CODE (arg
) == PARM_DECL
&& POINTER_TYPE_P (TREE_TYPE (arg
)));
312 /* The static chain decl is always non null. */
313 if (arg
== cfun
->static_chain_decl
)
316 fntype
= TREE_TYPE (current_function_decl
);
317 attrs
= lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype
));
319 /* If "nonnull" wasn't specified, we know nothing about the argument. */
320 if (attrs
== NULL_TREE
)
323 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
324 if (TREE_VALUE (attrs
) == NULL_TREE
)
327 /* Get the position number for ARG in the function signature. */
328 for (arg_num
= 1, t
= DECL_ARGUMENTS (current_function_decl
);
330 t
= TREE_CHAIN (t
), arg_num
++)
336 gcc_assert (t
== arg
);
338 /* Now see if ARG_NUM is mentioned in the nonnull list. */
339 for (t
= TREE_VALUE (attrs
); t
; t
= TREE_CHAIN (t
))
341 if (compare_tree_int (TREE_VALUE (t
), arg_num
) == 0)
349 /* Set value range VR to VR_VARYING. */
352 set_value_range_to_varying (value_range_t
*vr
)
354 vr
->type
= VR_VARYING
;
355 vr
->min
= vr
->max
= NULL_TREE
;
357 bitmap_clear (vr
->equiv
);
361 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
364 set_value_range (value_range_t
*vr
, enum value_range_type t
, tree min
,
365 tree max
, bitmap equiv
)
367 #if defined ENABLE_CHECKING
368 /* Check the validity of the range. */
369 if (t
== VR_RANGE
|| t
== VR_ANTI_RANGE
)
373 gcc_assert (min
&& max
);
375 if (INTEGRAL_TYPE_P (TREE_TYPE (min
)) && t
== VR_ANTI_RANGE
)
376 gcc_assert (!vrp_val_is_min (min
) || !vrp_val_is_max (max
));
378 cmp
= compare_values (min
, max
);
379 gcc_assert (cmp
== 0 || cmp
== -1 || cmp
== -2);
381 if (needs_overflow_infinity (TREE_TYPE (min
)))
382 gcc_assert (!is_overflow_infinity (min
)
383 || !is_overflow_infinity (max
));
386 if (t
== VR_UNDEFINED
|| t
== VR_VARYING
)
387 gcc_assert (min
== NULL_TREE
&& max
== NULL_TREE
);
389 if (t
== VR_UNDEFINED
|| t
== VR_VARYING
)
390 gcc_assert (equiv
== NULL
|| bitmap_empty_p (equiv
));
397 /* Since updating the equivalence set involves deep copying the
398 bitmaps, only do it if absolutely necessary. */
399 if (vr
->equiv
== NULL
401 vr
->equiv
= BITMAP_ALLOC (NULL
);
403 if (equiv
!= vr
->equiv
)
405 if (equiv
&& !bitmap_empty_p (equiv
))
406 bitmap_copy (vr
->equiv
, equiv
);
408 bitmap_clear (vr
->equiv
);
413 /* Set value range VR to the canonical form of {T, MIN, MAX, EQUIV}.
414 This means adjusting T, MIN and MAX representing the case of a
415 wrapping range with MAX < MIN covering [MIN, type_max] U [type_min, MAX]
416 as anti-rage ~[MAX+1, MIN-1]. Likewise for wrapping anti-ranges.
417 In corner cases where MAX+1 or MIN-1 wraps this will fall back
419 This routine exists to ease canonicalization in the case where we
420 extract ranges from var + CST op limit. */
423 set_and_canonicalize_value_range (value_range_t
*vr
, enum value_range_type t
,
424 tree min
, tree max
, bitmap equiv
)
426 /* Nothing to canonicalize for symbolic or unknown or varying ranges. */
428 && t
!= VR_ANTI_RANGE
)
429 || TREE_CODE (min
) != INTEGER_CST
430 || TREE_CODE (max
) != INTEGER_CST
)
432 set_value_range (vr
, t
, min
, max
, equiv
);
436 /* Wrong order for min and max, to swap them and the VR type we need
438 if (tree_int_cst_lt (max
, min
))
440 tree one
= build_int_cst (TREE_TYPE (min
), 1);
441 tree tmp
= int_const_binop (PLUS_EXPR
, max
, one
, 0);
442 max
= int_const_binop (MINUS_EXPR
, min
, one
, 0);
445 /* There's one corner case, if we had [C+1, C] before we now have
446 that again. But this represents an empty value range, so drop
447 to varying in this case. */
448 if (tree_int_cst_lt (max
, min
))
450 set_value_range_to_varying (vr
);
454 t
= t
== VR_RANGE
? VR_ANTI_RANGE
: VR_RANGE
;
457 /* Anti-ranges that can be represented as ranges should be so. */
458 if (t
== VR_ANTI_RANGE
)
460 bool is_min
= vrp_val_is_min (min
);
461 bool is_max
= vrp_val_is_max (max
);
463 if (is_min
&& is_max
)
465 /* We cannot deal with empty ranges, drop to varying. */
466 set_value_range_to_varying (vr
);
470 /* As a special exception preserve non-null ranges. */
471 && !(TYPE_UNSIGNED (TREE_TYPE (min
))
472 && integer_zerop (max
)))
474 tree one
= build_int_cst (TREE_TYPE (max
), 1);
475 min
= int_const_binop (PLUS_EXPR
, max
, one
, 0);
476 max
= vrp_val_max (TREE_TYPE (max
));
481 tree one
= build_int_cst (TREE_TYPE (min
), 1);
482 max
= int_const_binop (MINUS_EXPR
, min
, one
, 0);
483 min
= vrp_val_min (TREE_TYPE (min
));
488 set_value_range (vr
, t
, min
, max
, equiv
);
491 /* Copy value range FROM into value range TO. */
494 copy_value_range (value_range_t
*to
, value_range_t
*from
)
496 set_value_range (to
, from
->type
, from
->min
, from
->max
, from
->equiv
);
499 /* Set value range VR to a single value. This function is only called
500 with values we get from statements, and exists to clear the
501 TREE_OVERFLOW flag so that we don't think we have an overflow
502 infinity when we shouldn't. */
505 set_value_range_to_value (value_range_t
*vr
, tree val
, bitmap equiv
)
507 gcc_assert (is_gimple_min_invariant (val
));
508 val
= avoid_overflow_infinity (val
);
509 set_value_range (vr
, VR_RANGE
, val
, val
, equiv
);
512 /* Set value range VR to a non-negative range of type TYPE.
513 OVERFLOW_INFINITY indicates whether to use an overflow infinity
514 rather than TYPE_MAX_VALUE; this should be true if we determine
515 that the range is nonnegative based on the assumption that signed
516 overflow does not occur. */
519 set_value_range_to_nonnegative (value_range_t
*vr
, tree type
,
520 bool overflow_infinity
)
524 if (overflow_infinity
&& !supports_overflow_infinity (type
))
526 set_value_range_to_varying (vr
);
530 zero
= build_int_cst (type
, 0);
531 set_value_range (vr
, VR_RANGE
, zero
,
533 ? positive_overflow_infinity (type
)
534 : TYPE_MAX_VALUE (type
)),
538 /* Set value range VR to a non-NULL range of type TYPE. */
541 set_value_range_to_nonnull (value_range_t
*vr
, tree type
)
543 tree zero
= build_int_cst (type
, 0);
544 set_value_range (vr
, VR_ANTI_RANGE
, zero
, zero
, vr
->equiv
);
548 /* Set value range VR to a NULL range of type TYPE. */
551 set_value_range_to_null (value_range_t
*vr
, tree type
)
553 set_value_range_to_value (vr
, build_int_cst (type
, 0), vr
->equiv
);
557 /* Set value range VR to a range of a truthvalue of type TYPE. */
560 set_value_range_to_truthvalue (value_range_t
*vr
, tree type
)
562 if (TYPE_PRECISION (type
) == 1)
563 set_value_range_to_varying (vr
);
565 set_value_range (vr
, VR_RANGE
,
566 build_int_cst (type
, 0), build_int_cst (type
, 1),
571 /* Set value range VR to VR_UNDEFINED. */
574 set_value_range_to_undefined (value_range_t
*vr
)
576 vr
->type
= VR_UNDEFINED
;
577 vr
->min
= vr
->max
= NULL_TREE
;
579 bitmap_clear (vr
->equiv
);
583 /* Return value range information for VAR.
585 If we have no values ranges recorded (ie, VRP is not running), then
586 return NULL. Otherwise create an empty range if none existed for VAR. */
588 static value_range_t
*
589 get_value_range (const_tree var
)
593 unsigned ver
= SSA_NAME_VERSION (var
);
595 /* If we have no recorded ranges, then return NULL. */
603 /* Create a default value range. */
604 vr_value
[ver
] = vr
= XCNEW (value_range_t
);
606 /* Defer allocating the equivalence set. */
609 /* If VAR is a default definition, the variable can take any value
611 sym
= SSA_NAME_VAR (var
);
612 if (SSA_NAME_IS_DEFAULT_DEF (var
))
614 /* Try to use the "nonnull" attribute to create ~[0, 0]
615 anti-ranges for pointers. Note that this is only valid with
616 default definitions of PARM_DECLs. */
617 if (TREE_CODE (sym
) == PARM_DECL
618 && POINTER_TYPE_P (TREE_TYPE (sym
))
619 && nonnull_arg_p (sym
))
620 set_value_range_to_nonnull (vr
, TREE_TYPE (sym
));
622 set_value_range_to_varying (vr
);
628 /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */
631 vrp_operand_equal_p (const_tree val1
, const_tree val2
)
635 if (!val1
|| !val2
|| !operand_equal_p (val1
, val2
, 0))
637 if (is_overflow_infinity (val1
))
638 return is_overflow_infinity (val2
);
642 /* Return true, if the bitmaps B1 and B2 are equal. */
645 vrp_bitmap_equal_p (const_bitmap b1
, const_bitmap b2
)
649 && bitmap_equal_p (b1
, b2
)));
652 /* Update the value range and equivalence set for variable VAR to
653 NEW_VR. Return true if NEW_VR is different from VAR's previous
656 NOTE: This function assumes that NEW_VR is a temporary value range
657 object created for the sole purpose of updating VAR's range. The
658 storage used by the equivalence set from NEW_VR will be freed by
659 this function. Do not call update_value_range when NEW_VR
660 is the range object associated with another SSA name. */
663 update_value_range (const_tree var
, value_range_t
*new_vr
)
665 value_range_t
*old_vr
;
668 /* Update the value range, if necessary. */
669 old_vr
= get_value_range (var
);
670 is_new
= old_vr
->type
!= new_vr
->type
671 || !vrp_operand_equal_p (old_vr
->min
, new_vr
->min
)
672 || !vrp_operand_equal_p (old_vr
->max
, new_vr
->max
)
673 || !vrp_bitmap_equal_p (old_vr
->equiv
, new_vr
->equiv
);
676 set_value_range (old_vr
, new_vr
->type
, new_vr
->min
, new_vr
->max
,
679 BITMAP_FREE (new_vr
->equiv
);
685 /* Add VAR and VAR's equivalence set to EQUIV. This is the central
686 point where equivalence processing can be turned on/off. */
689 add_equivalence (bitmap
*equiv
, const_tree var
)
691 unsigned ver
= SSA_NAME_VERSION (var
);
692 value_range_t
*vr
= vr_value
[ver
];
695 *equiv
= BITMAP_ALLOC (NULL
);
696 bitmap_set_bit (*equiv
, ver
);
698 bitmap_ior_into (*equiv
, vr
->equiv
);
702 /* Return true if VR is ~[0, 0]. */
705 range_is_nonnull (value_range_t
*vr
)
707 return vr
->type
== VR_ANTI_RANGE
708 && integer_zerop (vr
->min
)
709 && integer_zerop (vr
->max
);
713 /* Return true if VR is [0, 0]. */
716 range_is_null (value_range_t
*vr
)
718 return vr
->type
== VR_RANGE
719 && integer_zerop (vr
->min
)
720 && integer_zerop (vr
->max
);
724 /* Return true if value range VR involves at least one symbol. */
727 symbolic_range_p (value_range_t
*vr
)
729 return (!is_gimple_min_invariant (vr
->min
)
730 || !is_gimple_min_invariant (vr
->max
));
733 /* Return true if value range VR uses an overflow infinity. */
736 overflow_infinity_range_p (value_range_t
*vr
)
738 return (vr
->type
== VR_RANGE
739 && (is_overflow_infinity (vr
->min
)
740 || is_overflow_infinity (vr
->max
)));
743 /* Return false if we can not make a valid comparison based on VR;
744 this will be the case if it uses an overflow infinity and overflow
745 is not undefined (i.e., -fno-strict-overflow is in effect).
746 Otherwise return true, and set *STRICT_OVERFLOW_P to true if VR
747 uses an overflow infinity. */
750 usable_range_p (value_range_t
*vr
, bool *strict_overflow_p
)
752 gcc_assert (vr
->type
== VR_RANGE
);
753 if (is_overflow_infinity (vr
->min
))
755 *strict_overflow_p
= true;
756 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr
->min
)))
759 if (is_overflow_infinity (vr
->max
))
761 *strict_overflow_p
= true;
762 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr
->max
)))
769 /* Like tree_expr_nonnegative_warnv_p, but this function uses value
770 ranges obtained so far. */
773 vrp_expr_computes_nonnegative (tree expr
, bool *strict_overflow_p
)
775 return tree_expr_nonnegative_warnv_p (expr
, strict_overflow_p
);
778 /* Like tree_expr_nonzero_warnv_p, but this function uses value ranges
782 vrp_expr_computes_nonzero (tree expr
, bool *strict_overflow_p
)
784 if (tree_expr_nonzero_warnv_p (expr
, strict_overflow_p
))
787 /* If we have an expression of the form &X->a, then the expression
788 is nonnull if X is nonnull. */
789 if (TREE_CODE (expr
) == ADDR_EXPR
)
791 tree base
= get_base_address (TREE_OPERAND (expr
, 0));
793 if (base
!= NULL_TREE
794 && TREE_CODE (base
) == INDIRECT_REF
795 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
797 value_range_t
*vr
= get_value_range (TREE_OPERAND (base
, 0));
798 if (range_is_nonnull (vr
))
806 /* Returns true if EXPR is a valid value (as expected by compare_values) --
807 a gimple invariant, or SSA_NAME +- CST. */
810 valid_value_p (tree expr
)
812 if (TREE_CODE (expr
) == SSA_NAME
)
815 if (TREE_CODE (expr
) == PLUS_EXPR
816 || TREE_CODE (expr
) == MINUS_EXPR
)
817 return (TREE_CODE (TREE_OPERAND (expr
, 0)) == SSA_NAME
818 && TREE_CODE (TREE_OPERAND (expr
, 1)) == INTEGER_CST
);
820 return is_gimple_min_invariant (expr
);
826 -2 if those are incomparable. */
828 operand_less_p (tree val
, tree val2
)
830 /* LT is folded faster than GE and others. Inline the common case. */
831 if (TREE_CODE (val
) == INTEGER_CST
&& TREE_CODE (val2
) == INTEGER_CST
)
833 if (TYPE_UNSIGNED (TREE_TYPE (val
)))
834 return INT_CST_LT_UNSIGNED (val
, val2
);
837 if (INT_CST_LT (val
, val2
))
845 fold_defer_overflow_warnings ();
847 tcmp
= fold_binary_to_constant (LT_EXPR
, boolean_type_node
, val
, val2
);
849 fold_undefer_and_ignore_overflow_warnings ();
852 || TREE_CODE (tcmp
) != INTEGER_CST
)
855 if (!integer_zerop (tcmp
))
859 /* val >= val2, not considering overflow infinity. */
860 if (is_negative_overflow_infinity (val
))
861 return is_negative_overflow_infinity (val2
) ? 0 : 1;
862 else if (is_positive_overflow_infinity (val2
))
863 return is_positive_overflow_infinity (val
) ? 0 : 1;
868 /* Compare two values VAL1 and VAL2. Return
870 -2 if VAL1 and VAL2 cannot be compared at compile-time,
873 +1 if VAL1 > VAL2, and
876 This is similar to tree_int_cst_compare but supports pointer values
877 and values that cannot be compared at compile time.
879 If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to
880 true if the return value is only valid if we assume that signed
881 overflow is undefined. */
884 compare_values_warnv (tree val1
, tree val2
, bool *strict_overflow_p
)
889 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
891 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1
))
892 == POINTER_TYPE_P (TREE_TYPE (val2
)));
893 /* Convert the two values into the same type. This is needed because
894 sizetype causes sign extension even for unsigned types. */
895 val2
= fold_convert (TREE_TYPE (val1
), val2
);
896 STRIP_USELESS_TYPE_CONVERSION (val2
);
898 if ((TREE_CODE (val1
) == SSA_NAME
899 || TREE_CODE (val1
) == PLUS_EXPR
900 || TREE_CODE (val1
) == MINUS_EXPR
)
901 && (TREE_CODE (val2
) == SSA_NAME
902 || TREE_CODE (val2
) == PLUS_EXPR
903 || TREE_CODE (val2
) == MINUS_EXPR
))
906 enum tree_code code1
, code2
;
908 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
909 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
910 same name, return -2. */
911 if (TREE_CODE (val1
) == SSA_NAME
)
919 code1
= TREE_CODE (val1
);
920 n1
= TREE_OPERAND (val1
, 0);
921 c1
= TREE_OPERAND (val1
, 1);
922 if (tree_int_cst_sgn (c1
) == -1)
924 if (is_negative_overflow_infinity (c1
))
926 c1
= fold_unary_to_constant (NEGATE_EXPR
, TREE_TYPE (c1
), c1
);
929 code1
= code1
== MINUS_EXPR
? PLUS_EXPR
: MINUS_EXPR
;
933 if (TREE_CODE (val2
) == SSA_NAME
)
941 code2
= TREE_CODE (val2
);
942 n2
= TREE_OPERAND (val2
, 0);
943 c2
= TREE_OPERAND (val2
, 1);
944 if (tree_int_cst_sgn (c2
) == -1)
946 if (is_negative_overflow_infinity (c2
))
948 c2
= fold_unary_to_constant (NEGATE_EXPR
, TREE_TYPE (c2
), c2
);
951 code2
= code2
== MINUS_EXPR
? PLUS_EXPR
: MINUS_EXPR
;
955 /* Both values must use the same name. */
959 if (code1
== SSA_NAME
960 && code2
== SSA_NAME
)
964 /* If overflow is defined we cannot simplify more. */
965 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1
)))
968 if (strict_overflow_p
!= NULL
969 && (code1
== SSA_NAME
|| !TREE_NO_WARNING (val1
))
970 && (code2
== SSA_NAME
|| !TREE_NO_WARNING (val2
)))
971 *strict_overflow_p
= true;
973 if (code1
== SSA_NAME
)
975 if (code2
== PLUS_EXPR
)
976 /* NAME < NAME + CST */
978 else if (code2
== MINUS_EXPR
)
979 /* NAME > NAME - CST */
982 else if (code1
== PLUS_EXPR
)
984 if (code2
== SSA_NAME
)
985 /* NAME + CST > NAME */
987 else if (code2
== PLUS_EXPR
)
988 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
989 return compare_values_warnv (c1
, c2
, strict_overflow_p
);
990 else if (code2
== MINUS_EXPR
)
991 /* NAME + CST1 > NAME - CST2 */
994 else if (code1
== MINUS_EXPR
)
996 if (code2
== SSA_NAME
)
997 /* NAME - CST < NAME */
999 else if (code2
== PLUS_EXPR
)
1000 /* NAME - CST1 < NAME + CST2 */
1002 else if (code2
== MINUS_EXPR
)
1003 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
1004 C1 and C2 are swapped in the call to compare_values. */
1005 return compare_values_warnv (c2
, c1
, strict_overflow_p
);
1011 /* We cannot compare non-constants. */
1012 if (!is_gimple_min_invariant (val1
) || !is_gimple_min_invariant (val2
))
1015 if (!POINTER_TYPE_P (TREE_TYPE (val1
)))
1017 /* We cannot compare overflowed values, except for overflow
1019 if (TREE_OVERFLOW (val1
) || TREE_OVERFLOW (val2
))
1021 if (strict_overflow_p
!= NULL
)
1022 *strict_overflow_p
= true;
1023 if (is_negative_overflow_infinity (val1
))
1024 return is_negative_overflow_infinity (val2
) ? 0 : -1;
1025 else if (is_negative_overflow_infinity (val2
))
1027 else if (is_positive_overflow_infinity (val1
))
1028 return is_positive_overflow_infinity (val2
) ? 0 : 1;
1029 else if (is_positive_overflow_infinity (val2
))
1034 return tree_int_cst_compare (val1
, val2
);
1040 /* First see if VAL1 and VAL2 are not the same. */
1041 if (val1
== val2
|| operand_equal_p (val1
, val2
, 0))
1044 /* If VAL1 is a lower address than VAL2, return -1. */
1045 if (operand_less_p (val1
, val2
) == 1)
1048 /* If VAL1 is a higher address than VAL2, return +1. */
1049 if (operand_less_p (val2
, val1
) == 1)
1052 /* If VAL1 is different than VAL2, return +2.
1053 For integer constants we either have already returned -1 or 1
1054 or they are equivalent. We still might succeed in proving
1055 something about non-trivial operands. */
1056 if (TREE_CODE (val1
) != INTEGER_CST
1057 || TREE_CODE (val2
) != INTEGER_CST
)
1059 t
= fold_binary_to_constant (NE_EXPR
, boolean_type_node
, val1
, val2
);
1060 if (t
&& integer_onep (t
))
1068 /* Compare values like compare_values_warnv, but treat comparisons of
1069 nonconstants which rely on undefined overflow as incomparable. */
1072 compare_values (tree val1
, tree val2
)
1078 ret
= compare_values_warnv (val1
, val2
, &sop
);
1080 && (!is_gimple_min_invariant (val1
) || !is_gimple_min_invariant (val2
)))
1086 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
1087 0 if VAL is not inside VR,
1088 -2 if we cannot tell either way.
1090 FIXME, the current semantics of this functions are a bit quirky
1091 when taken in the context of VRP. In here we do not care
1092 about VR's type. If VR is the anti-range ~[3, 5] the call
1093 value_inside_range (4, VR) will return 1.
1095 This is counter-intuitive in a strict sense, but the callers
1096 currently expect this. They are calling the function
1097 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
1098 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
1101 This also applies to value_ranges_intersect_p and
1102 range_includes_zero_p. The semantics of VR_RANGE and
1103 VR_ANTI_RANGE should be encoded here, but that also means
1104 adapting the users of these functions to the new semantics.
1106 Benchmark compile/20001226-1.c compilation time after changing this
1110 value_inside_range (tree val
, value_range_t
* vr
)
1114 cmp1
= operand_less_p (val
, vr
->min
);
1120 cmp2
= operand_less_p (vr
->max
, val
);
1128 /* Return true if value ranges VR0 and VR1 have a non-empty
1131 Benchmark compile/20001226-1.c compilation time after changing this
1136 value_ranges_intersect_p (value_range_t
*vr0
, value_range_t
*vr1
)
1138 /* The value ranges do not intersect if the maximum of the first range is
1139 less than the minimum of the second range or vice versa.
1140 When those relations are unknown, we can't do any better. */
1141 if (operand_less_p (vr0
->max
, vr1
->min
) != 0)
1143 if (operand_less_p (vr1
->max
, vr0
->min
) != 0)
1149 /* Return true if VR includes the value zero, false otherwise. FIXME,
1150 currently this will return false for an anti-range like ~[-4, 3].
1151 This will be wrong when the semantics of value_inside_range are
1152 modified (currently the users of this function expect these
1156 range_includes_zero_p (value_range_t
*vr
)
1160 gcc_assert (vr
->type
!= VR_UNDEFINED
1161 && vr
->type
!= VR_VARYING
1162 && !symbolic_range_p (vr
));
1164 zero
= build_int_cst (TREE_TYPE (vr
->min
), 0);
1165 return (value_inside_range (zero
, vr
) == 1);
1168 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
1169 false otherwise or if no value range information is available. */
1172 ssa_name_nonnegative_p (const_tree t
)
1174 value_range_t
*vr
= get_value_range (t
);
1179 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
1180 which would return a useful value should be encoded as a VR_RANGE. */
1181 if (vr
->type
== VR_RANGE
)
1183 int result
= compare_values (vr
->min
, integer_zero_node
);
1185 return (result
== 0 || result
== 1);
1190 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
1191 false otherwise or if no value range information is available. */
1194 ssa_name_nonzero_p (const_tree t
)
1196 value_range_t
*vr
= get_value_range (t
);
1201 /* A VR_RANGE which does not include zero is a nonzero value. */
1202 if (vr
->type
== VR_RANGE
&& !symbolic_range_p (vr
))
1203 return ! range_includes_zero_p (vr
);
1205 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
1206 if (vr
->type
== VR_ANTI_RANGE
&& !symbolic_range_p (vr
))
1207 return range_includes_zero_p (vr
);
1213 /* Extract value range information from an ASSERT_EXPR EXPR and store
1217 extract_range_from_assert (value_range_t
*vr_p
, tree expr
)
1219 tree var
, cond
, limit
, min
, max
, type
;
1220 value_range_t
*var_vr
, *limit_vr
;
1221 enum tree_code cond_code
;
1223 var
= ASSERT_EXPR_VAR (expr
);
1224 cond
= ASSERT_EXPR_COND (expr
);
1226 gcc_assert (COMPARISON_CLASS_P (cond
));
1228 /* Find VAR in the ASSERT_EXPR conditional. */
1229 if (var
== TREE_OPERAND (cond
, 0)
1230 || TREE_CODE (TREE_OPERAND (cond
, 0)) == PLUS_EXPR
1231 || TREE_CODE (TREE_OPERAND (cond
, 0)) == NOP_EXPR
)
1233 /* If the predicate is of the form VAR COMP LIMIT, then we just
1234 take LIMIT from the RHS and use the same comparison code. */
1235 cond_code
= TREE_CODE (cond
);
1236 limit
= TREE_OPERAND (cond
, 1);
1237 cond
= TREE_OPERAND (cond
, 0);
1241 /* If the predicate is of the form LIMIT COMP VAR, then we need
1242 to flip around the comparison code to create the proper range
1244 cond_code
= swap_tree_comparison (TREE_CODE (cond
));
1245 limit
= TREE_OPERAND (cond
, 0);
1246 cond
= TREE_OPERAND (cond
, 1);
1249 limit
= avoid_overflow_infinity (limit
);
1251 type
= TREE_TYPE (limit
);
1252 gcc_assert (limit
!= var
);
1254 /* For pointer arithmetic, we only keep track of pointer equality
1256 if (POINTER_TYPE_P (type
) && cond_code
!= NE_EXPR
&& cond_code
!= EQ_EXPR
)
1258 set_value_range_to_varying (vr_p
);
1262 /* If LIMIT is another SSA name and LIMIT has a range of its own,
1263 try to use LIMIT's range to avoid creating symbolic ranges
1265 limit_vr
= (TREE_CODE (limit
) == SSA_NAME
) ? get_value_range (limit
) : NULL
;
1267 /* LIMIT's range is only interesting if it has any useful information. */
1269 && (limit_vr
->type
== VR_UNDEFINED
1270 || limit_vr
->type
== VR_VARYING
1271 || symbolic_range_p (limit_vr
)))
1274 /* Initially, the new range has the same set of equivalences of
1275 VAR's range. This will be revised before returning the final
1276 value. Since assertions may be chained via mutually exclusive
1277 predicates, we will need to trim the set of equivalences before
1279 gcc_assert (vr_p
->equiv
== NULL
);
1280 add_equivalence (&vr_p
->equiv
, var
);
1282 /* Extract a new range based on the asserted comparison for VAR and
1283 LIMIT's value range. Notice that if LIMIT has an anti-range, we
1284 will only use it for equality comparisons (EQ_EXPR). For any
1285 other kind of assertion, we cannot derive a range from LIMIT's
1286 anti-range that can be used to describe the new range. For
1287 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
1288 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
1289 no single range for x_2 that could describe LE_EXPR, so we might
1290 as well build the range [b_4, +INF] for it.
1291 One special case we handle is extracting a range from a
1292 range test encoded as (unsigned)var + CST <= limit. */
1293 if (TREE_CODE (cond
) == NOP_EXPR
1294 || TREE_CODE (cond
) == PLUS_EXPR
)
1296 if (TREE_CODE (cond
) == PLUS_EXPR
)
1298 min
= fold_build1 (NEGATE_EXPR
, TREE_TYPE (TREE_OPERAND (cond
, 1)),
1299 TREE_OPERAND (cond
, 1));
1300 max
= int_const_binop (PLUS_EXPR
, limit
, min
, 0);
1301 cond
= TREE_OPERAND (cond
, 0);
1305 min
= build_int_cst (TREE_TYPE (var
), 0);
1309 /* Make sure to not set TREE_OVERFLOW on the final type
1310 conversion. We are willingly interpreting large positive
1311 unsigned values as negative singed values here. */
1312 min
= force_fit_type_double (TREE_TYPE (var
), TREE_INT_CST_LOW (min
),
1313 TREE_INT_CST_HIGH (min
), 0, false);
1314 max
= force_fit_type_double (TREE_TYPE (var
), TREE_INT_CST_LOW (max
),
1315 TREE_INT_CST_HIGH (max
), 0, false);
1317 /* We can transform a max, min range to an anti-range or
1318 vice-versa. Use set_and_canonicalize_value_range which does
1320 if (cond_code
== LE_EXPR
)
1321 set_and_canonicalize_value_range (vr_p
, VR_RANGE
,
1322 min
, max
, vr_p
->equiv
);
1323 else if (cond_code
== GT_EXPR
)
1324 set_and_canonicalize_value_range (vr_p
, VR_ANTI_RANGE
,
1325 min
, max
, vr_p
->equiv
);
1329 else if (cond_code
== EQ_EXPR
)
1331 enum value_range_type range_type
;
1335 range_type
= limit_vr
->type
;
1336 min
= limit_vr
->min
;
1337 max
= limit_vr
->max
;
1341 range_type
= VR_RANGE
;
1346 set_value_range (vr_p
, range_type
, min
, max
, vr_p
->equiv
);
1348 /* When asserting the equality VAR == LIMIT and LIMIT is another
1349 SSA name, the new range will also inherit the equivalence set
1351 if (TREE_CODE (limit
) == SSA_NAME
)
1352 add_equivalence (&vr_p
->equiv
, limit
);
1354 else if (cond_code
== NE_EXPR
)
1356 /* As described above, when LIMIT's range is an anti-range and
1357 this assertion is an inequality (NE_EXPR), then we cannot
1358 derive anything from the anti-range. For instance, if
1359 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
1360 not imply that VAR's range is [0, 0]. So, in the case of
1361 anti-ranges, we just assert the inequality using LIMIT and
1364 If LIMIT_VR is a range, we can only use it to build a new
1365 anti-range if LIMIT_VR is a single-valued range. For
1366 instance, if LIMIT_VR is [0, 1], the predicate
1367 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
1368 Rather, it means that for value 0 VAR should be ~[0, 0]
1369 and for value 1, VAR should be ~[1, 1]. We cannot
1370 represent these ranges.
1372 The only situation in which we can build a valid
1373 anti-range is when LIMIT_VR is a single-valued range
1374 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
1375 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
1377 && limit_vr
->type
== VR_RANGE
1378 && compare_values (limit_vr
->min
, limit_vr
->max
) == 0)
1380 min
= limit_vr
->min
;
1381 max
= limit_vr
->max
;
1385 /* In any other case, we cannot use LIMIT's range to build a
1386 valid anti-range. */
1390 /* If MIN and MAX cover the whole range for their type, then
1391 just use the original LIMIT. */
1392 if (INTEGRAL_TYPE_P (type
)
1393 && vrp_val_is_min (min
)
1394 && vrp_val_is_max (max
))
1397 set_value_range (vr_p
, VR_ANTI_RANGE
, min
, max
, vr_p
->equiv
);
1399 else if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
1401 min
= TYPE_MIN_VALUE (type
);
1403 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
1407 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1408 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
1410 max
= limit_vr
->max
;
1413 /* If the maximum value forces us to be out of bounds, simply punt.
1414 It would be pointless to try and do anything more since this
1415 all should be optimized away above us. */
1416 if ((cond_code
== LT_EXPR
1417 && compare_values (max
, min
) == 0)
1418 || is_overflow_infinity (max
))
1419 set_value_range_to_varying (vr_p
);
1422 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
1423 if (cond_code
== LT_EXPR
)
1425 tree one
= build_int_cst (type
, 1);
1426 max
= fold_build2 (MINUS_EXPR
, type
, max
, one
);
1428 TREE_NO_WARNING (max
) = 1;
1431 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1434 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
1436 max
= TYPE_MAX_VALUE (type
);
1438 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
1442 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1443 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
1445 min
= limit_vr
->min
;
1448 /* If the minimum value forces us to be out of bounds, simply punt.
1449 It would be pointless to try and do anything more since this
1450 all should be optimized away above us. */
1451 if ((cond_code
== GT_EXPR
1452 && compare_values (min
, max
) == 0)
1453 || is_overflow_infinity (min
))
1454 set_value_range_to_varying (vr_p
);
1457 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
1458 if (cond_code
== GT_EXPR
)
1460 tree one
= build_int_cst (type
, 1);
1461 min
= fold_build2 (PLUS_EXPR
, type
, min
, one
);
1463 TREE_NO_WARNING (min
) = 1;
1466 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1472 /* If VAR already had a known range, it may happen that the new
1473 range we have computed and VAR's range are not compatible. For
1477 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
1479 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
1481 While the above comes from a faulty program, it will cause an ICE
1482 later because p_8 and p_6 will have incompatible ranges and at
1483 the same time will be considered equivalent. A similar situation
1487 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
1489 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
1491 Again i_6 and i_7 will have incompatible ranges. It would be
1492 pointless to try and do anything with i_7's range because
1493 anything dominated by 'if (i_5 < 5)' will be optimized away.
1494 Note, due to the wa in which simulation proceeds, the statement
1495 i_7 = ASSERT_EXPR <...> we would never be visited because the
1496 conditional 'if (i_5 < 5)' always evaluates to false. However,
1497 this extra check does not hurt and may protect against future
1498 changes to VRP that may get into a situation similar to the
1499 NULL pointer dereference example.
1501 Note that these compatibility tests are only needed when dealing
1502 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1503 are both anti-ranges, they will always be compatible, because two
1504 anti-ranges will always have a non-empty intersection. */
1506 var_vr
= get_value_range (var
);
1508 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1509 ranges or anti-ranges. */
1510 if (vr_p
->type
== VR_VARYING
1511 || vr_p
->type
== VR_UNDEFINED
1512 || var_vr
->type
== VR_VARYING
1513 || var_vr
->type
== VR_UNDEFINED
1514 || symbolic_range_p (vr_p
)
1515 || symbolic_range_p (var_vr
))
1518 if (var_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_RANGE
)
1520 /* If the two ranges have a non-empty intersection, we can
1521 refine the resulting range. Since the assert expression
1522 creates an equivalency and at the same time it asserts a
1523 predicate, we can take the intersection of the two ranges to
1524 get better precision. */
1525 if (value_ranges_intersect_p (var_vr
, vr_p
))
1527 /* Use the larger of the two minimums. */
1528 if (compare_values (vr_p
->min
, var_vr
->min
) == -1)
1533 /* Use the smaller of the two maximums. */
1534 if (compare_values (vr_p
->max
, var_vr
->max
) == 1)
1539 set_value_range (vr_p
, vr_p
->type
, min
, max
, vr_p
->equiv
);
1543 /* The two ranges do not intersect, set the new range to
1544 VARYING, because we will not be able to do anything
1545 meaningful with it. */
1546 set_value_range_to_varying (vr_p
);
1549 else if ((var_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_ANTI_RANGE
)
1550 || (var_vr
->type
== VR_ANTI_RANGE
&& vr_p
->type
== VR_RANGE
))
1552 /* A range and an anti-range will cancel each other only if
1553 their ends are the same. For instance, in the example above,
1554 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1555 so VR_P should be set to VR_VARYING. */
1556 if (compare_values (var_vr
->min
, vr_p
->min
) == 0
1557 && compare_values (var_vr
->max
, vr_p
->max
) == 0)
1558 set_value_range_to_varying (vr_p
);
1561 tree min
, max
, anti_min
, anti_max
, real_min
, real_max
;
1564 /* We want to compute the logical AND of the two ranges;
1565 there are three cases to consider.
1568 1. The VR_ANTI_RANGE range is completely within the
1569 VR_RANGE and the endpoints of the ranges are
1570 different. In that case the resulting range
1571 should be whichever range is more precise.
1572 Typically that will be the VR_RANGE.
1574 2. The VR_ANTI_RANGE is completely disjoint from
1575 the VR_RANGE. In this case the resulting range
1576 should be the VR_RANGE.
1578 3. There is some overlap between the VR_ANTI_RANGE
1581 3a. If the high limit of the VR_ANTI_RANGE resides
1582 within the VR_RANGE, then the result is a new
1583 VR_RANGE starting at the high limit of the
1584 the VR_ANTI_RANGE + 1 and extending to the
1585 high limit of the original VR_RANGE.
1587 3b. If the low limit of the VR_ANTI_RANGE resides
1588 within the VR_RANGE, then the result is a new
1589 VR_RANGE starting at the low limit of the original
1590 VR_RANGE and extending to the low limit of the
1591 VR_ANTI_RANGE - 1. */
1592 if (vr_p
->type
== VR_ANTI_RANGE
)
1594 anti_min
= vr_p
->min
;
1595 anti_max
= vr_p
->max
;
1596 real_min
= var_vr
->min
;
1597 real_max
= var_vr
->max
;
1601 anti_min
= var_vr
->min
;
1602 anti_max
= var_vr
->max
;
1603 real_min
= vr_p
->min
;
1604 real_max
= vr_p
->max
;
1608 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1609 not including any endpoints. */
1610 if (compare_values (anti_max
, real_max
) == -1
1611 && compare_values (anti_min
, real_min
) == 1)
1613 /* If the range is covering the whole valid range of
1614 the type keep the anti-range. */
1615 if (!vrp_val_is_min (real_min
)
1616 || !vrp_val_is_max (real_max
))
1617 set_value_range (vr_p
, VR_RANGE
, real_min
,
1618 real_max
, vr_p
->equiv
);
1620 /* Case 2, VR_ANTI_RANGE completely disjoint from
1622 else if (compare_values (anti_min
, real_max
) == 1
1623 || compare_values (anti_max
, real_min
) == -1)
1625 set_value_range (vr_p
, VR_RANGE
, real_min
,
1626 real_max
, vr_p
->equiv
);
1628 /* Case 3a, the anti-range extends into the low
1629 part of the real range. Thus creating a new
1630 low for the real range. */
1631 else if (((cmp
= compare_values (anti_max
, real_min
)) == 1
1633 && compare_values (anti_max
, real_max
) == -1)
1635 gcc_assert (!is_positive_overflow_infinity (anti_max
));
1636 if (needs_overflow_infinity (TREE_TYPE (anti_max
))
1637 && vrp_val_is_max (anti_max
))
1639 if (!supports_overflow_infinity (TREE_TYPE (var_vr
->min
)))
1641 set_value_range_to_varying (vr_p
);
1644 min
= positive_overflow_infinity (TREE_TYPE (var_vr
->min
));
1646 else if (!POINTER_TYPE_P (TREE_TYPE (var_vr
->min
)))
1647 min
= fold_build2 (PLUS_EXPR
, TREE_TYPE (var_vr
->min
),
1649 build_int_cst (TREE_TYPE (var_vr
->min
), 1));
1651 min
= fold_build2 (POINTER_PLUS_EXPR
, TREE_TYPE (var_vr
->min
),
1652 anti_max
, size_int (1));
1654 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1656 /* Case 3b, the anti-range extends into the high
1657 part of the real range. Thus creating a new
1658 higher for the real range. */
1659 else if (compare_values (anti_min
, real_min
) == 1
1660 && ((cmp
= compare_values (anti_min
, real_max
)) == -1
1663 gcc_assert (!is_negative_overflow_infinity (anti_min
));
1664 if (needs_overflow_infinity (TREE_TYPE (anti_min
))
1665 && vrp_val_is_min (anti_min
))
1667 if (!supports_overflow_infinity (TREE_TYPE (var_vr
->min
)))
1669 set_value_range_to_varying (vr_p
);
1672 max
= negative_overflow_infinity (TREE_TYPE (var_vr
->min
));
1674 else if (!POINTER_TYPE_P (TREE_TYPE (var_vr
->min
)))
1675 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (var_vr
->min
),
1677 build_int_cst (TREE_TYPE (var_vr
->min
), 1));
1679 max
= fold_build2 (POINTER_PLUS_EXPR
, TREE_TYPE (var_vr
->min
),
1683 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1690 /* Extract range information from SSA name VAR and store it in VR. If
1691 VAR has an interesting range, use it. Otherwise, create the
1692 range [VAR, VAR] and return it. This is useful in situations where
1693 we may have conditionals testing values of VARYING names. For
1700 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1704 extract_range_from_ssa_name (value_range_t
*vr
, tree var
)
1706 value_range_t
*var_vr
= get_value_range (var
);
1708 if (var_vr
->type
!= VR_UNDEFINED
&& var_vr
->type
!= VR_VARYING
)
1709 copy_value_range (vr
, var_vr
);
1711 set_value_range (vr
, VR_RANGE
, var
, var
, NULL
);
1713 add_equivalence (&vr
->equiv
, var
);
1717 /* Wrapper around int_const_binop. If the operation overflows and we
1718 are not using wrapping arithmetic, then adjust the result to be
1719 -INF or +INF depending on CODE, VAL1 and VAL2. This can return
1720 NULL_TREE if we need to use an overflow infinity representation but
1721 the type does not support it. */
1724 vrp_int_const_binop (enum tree_code code
, tree val1
, tree val2
)
1728 res
= int_const_binop (code
, val1
, val2
, 0);
1730 /* If we are not using wrapping arithmetic, operate symbolically
1731 on -INF and +INF. */
1732 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1
)))
1734 int checkz
= compare_values (res
, val1
);
1735 bool overflow
= false;
1737 /* Ensure that res = val1 [+*] val2 >= val1
1738 or that res = val1 - val2 <= val1. */
1739 if ((code
== PLUS_EXPR
1740 && !(checkz
== 1 || checkz
== 0))
1741 || (code
== MINUS_EXPR
1742 && !(checkz
== 0 || checkz
== -1)))
1746 /* Checking for multiplication overflow is done by dividing the
1747 output of the multiplication by the first input of the
1748 multiplication. If the result of that division operation is
1749 not equal to the second input of the multiplication, then the
1750 multiplication overflowed. */
1751 else if (code
== MULT_EXPR
&& !integer_zerop (val1
))
1753 tree tmp
= int_const_binop (TRUNC_DIV_EXPR
,
1756 int check
= compare_values (tmp
, val2
);
1764 res
= copy_node (res
);
1765 TREE_OVERFLOW (res
) = 1;
1769 else if ((TREE_OVERFLOW (res
)
1770 && !TREE_OVERFLOW (val1
)
1771 && !TREE_OVERFLOW (val2
))
1772 || is_overflow_infinity (val1
)
1773 || is_overflow_infinity (val2
))
1775 /* If the operation overflowed but neither VAL1 nor VAL2 are
1776 overflown, return -INF or +INF depending on the operation
1777 and the combination of signs of the operands. */
1778 int sgn1
= tree_int_cst_sgn (val1
);
1779 int sgn2
= tree_int_cst_sgn (val2
);
1781 if (needs_overflow_infinity (TREE_TYPE (res
))
1782 && !supports_overflow_infinity (TREE_TYPE (res
)))
1785 /* We have to punt on adding infinities of different signs,
1786 since we can't tell what the sign of the result should be.
1787 Likewise for subtracting infinities of the same sign. */
1788 if (((code
== PLUS_EXPR
&& sgn1
!= sgn2
)
1789 || (code
== MINUS_EXPR
&& sgn1
== sgn2
))
1790 && is_overflow_infinity (val1
)
1791 && is_overflow_infinity (val2
))
1794 /* Don't try to handle division or shifting of infinities. */
1795 if ((code
== TRUNC_DIV_EXPR
1796 || code
== FLOOR_DIV_EXPR
1797 || code
== CEIL_DIV_EXPR
1798 || code
== EXACT_DIV_EXPR
1799 || code
== ROUND_DIV_EXPR
1800 || code
== RSHIFT_EXPR
)
1801 && (is_overflow_infinity (val1
)
1802 || is_overflow_infinity (val2
)))
1805 /* Notice that we only need to handle the restricted set of
1806 operations handled by extract_range_from_binary_expr.
1807 Among them, only multiplication, addition and subtraction
1808 can yield overflow without overflown operands because we
1809 are working with integral types only... except in the
1810 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1811 for division too. */
1813 /* For multiplication, the sign of the overflow is given
1814 by the comparison of the signs of the operands. */
1815 if ((code
== MULT_EXPR
&& sgn1
== sgn2
)
1816 /* For addition, the operands must be of the same sign
1817 to yield an overflow. Its sign is therefore that
1818 of one of the operands, for example the first. For
1819 infinite operands X + -INF is negative, not positive. */
1820 || (code
== PLUS_EXPR
1822 ? !is_negative_overflow_infinity (val2
)
1823 : is_positive_overflow_infinity (val2
)))
1824 /* For subtraction, non-infinite operands must be of
1825 different signs to yield an overflow. Its sign is
1826 therefore that of the first operand or the opposite of
1827 that of the second operand. A first operand of 0 counts
1828 as positive here, for the corner case 0 - (-INF), which
1829 overflows, but must yield +INF. For infinite operands 0
1830 - INF is negative, not positive. */
1831 || (code
== MINUS_EXPR
1833 ? !is_positive_overflow_infinity (val2
)
1834 : is_negative_overflow_infinity (val2
)))
1835 /* We only get in here with positive shift count, so the
1836 overflow direction is the same as the sign of val1.
1837 Actually rshift does not overflow at all, but we only
1838 handle the case of shifting overflowed -INF and +INF. */
1839 || (code
== RSHIFT_EXPR
1841 /* For division, the only case is -INF / -1 = +INF. */
1842 || code
== TRUNC_DIV_EXPR
1843 || code
== FLOOR_DIV_EXPR
1844 || code
== CEIL_DIV_EXPR
1845 || code
== EXACT_DIV_EXPR
1846 || code
== ROUND_DIV_EXPR
)
1847 return (needs_overflow_infinity (TREE_TYPE (res
))
1848 ? positive_overflow_infinity (TREE_TYPE (res
))
1849 : TYPE_MAX_VALUE (TREE_TYPE (res
)));
1851 return (needs_overflow_infinity (TREE_TYPE (res
))
1852 ? negative_overflow_infinity (TREE_TYPE (res
))
1853 : TYPE_MIN_VALUE (TREE_TYPE (res
)));
1860 /* Extract range information from a binary expression EXPR based on
1861 the ranges of each of its operands and the expression code. */
1864 extract_range_from_binary_expr (value_range_t
*vr
,
1865 enum tree_code code
,
1866 tree expr_type
, tree op0
, tree op1
)
1868 enum value_range_type type
;
1871 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1872 value_range_t vr1
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1874 /* Not all binary expressions can be applied to ranges in a
1875 meaningful way. Handle only arithmetic operations. */
1876 if (code
!= PLUS_EXPR
1877 && code
!= MINUS_EXPR
1878 && code
!= POINTER_PLUS_EXPR
1879 && code
!= MULT_EXPR
1880 && code
!= TRUNC_DIV_EXPR
1881 && code
!= FLOOR_DIV_EXPR
1882 && code
!= CEIL_DIV_EXPR
1883 && code
!= EXACT_DIV_EXPR
1884 && code
!= ROUND_DIV_EXPR
1885 && code
!= RSHIFT_EXPR
1888 && code
!= BIT_AND_EXPR
1889 && code
!= TRUTH_AND_EXPR
1890 && code
!= TRUTH_OR_EXPR
)
1892 set_value_range_to_varying (vr
);
1896 /* Get value ranges for each operand. For constant operands, create
1897 a new value range with the operand to simplify processing. */
1898 if (TREE_CODE (op0
) == SSA_NAME
)
1899 vr0
= *(get_value_range (op0
));
1900 else if (is_gimple_min_invariant (op0
))
1901 set_value_range_to_value (&vr0
, op0
, NULL
);
1903 set_value_range_to_varying (&vr0
);
1905 if (TREE_CODE (op1
) == SSA_NAME
)
1906 vr1
= *(get_value_range (op1
));
1907 else if (is_gimple_min_invariant (op1
))
1908 set_value_range_to_value (&vr1
, op1
, NULL
);
1910 set_value_range_to_varying (&vr1
);
1912 /* If either range is UNDEFINED, so is the result. */
1913 if (vr0
.type
== VR_UNDEFINED
|| vr1
.type
== VR_UNDEFINED
)
1915 set_value_range_to_undefined (vr
);
1919 /* The type of the resulting value range defaults to VR0.TYPE. */
1922 /* Refuse to operate on VARYING ranges, ranges of different kinds
1923 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1924 because we may be able to derive a useful range even if one of
1925 the operands is VR_VARYING or symbolic range. TODO, we may be
1926 able to derive anti-ranges in some cases. */
1927 if (code
!= BIT_AND_EXPR
1928 && code
!= TRUTH_AND_EXPR
1929 && code
!= TRUTH_OR_EXPR
1930 && (vr0
.type
== VR_VARYING
1931 || vr1
.type
== VR_VARYING
1932 || vr0
.type
!= vr1
.type
1933 || symbolic_range_p (&vr0
)
1934 || symbolic_range_p (&vr1
)))
1936 set_value_range_to_varying (vr
);
1940 /* Now evaluate the expression to determine the new range. */
1941 if (POINTER_TYPE_P (expr_type
)
1942 || POINTER_TYPE_P (TREE_TYPE (op0
))
1943 || POINTER_TYPE_P (TREE_TYPE (op1
)))
1945 if (code
== MIN_EXPR
|| code
== MAX_EXPR
)
1947 /* For MIN/MAX expressions with pointers, we only care about
1948 nullness, if both are non null, then the result is nonnull.
1949 If both are null, then the result is null. Otherwise they
1951 if (range_is_nonnull (&vr0
) && range_is_nonnull (&vr1
))
1952 set_value_range_to_nonnull (vr
, expr_type
);
1953 else if (range_is_null (&vr0
) && range_is_null (&vr1
))
1954 set_value_range_to_null (vr
, expr_type
);
1956 set_value_range_to_varying (vr
);
1960 gcc_assert (code
== POINTER_PLUS_EXPR
);
1961 /* For pointer types, we are really only interested in asserting
1962 whether the expression evaluates to non-NULL. */
1963 if (range_is_nonnull (&vr0
) || range_is_nonnull (&vr1
))
1964 set_value_range_to_nonnull (vr
, expr_type
);
1965 else if (range_is_null (&vr0
) && range_is_null (&vr1
))
1966 set_value_range_to_null (vr
, expr_type
);
1968 set_value_range_to_varying (vr
);
1973 /* For integer ranges, apply the operation to each end of the
1974 range and see what we end up with. */
1975 if (code
== TRUTH_AND_EXPR
1976 || code
== TRUTH_OR_EXPR
)
1978 /* If one of the operands is zero, we know that the whole
1979 expression evaluates zero. */
1980 if (code
== TRUTH_AND_EXPR
1981 && ((vr0
.type
== VR_RANGE
1982 && integer_zerop (vr0
.min
)
1983 && integer_zerop (vr0
.max
))
1984 || (vr1
.type
== VR_RANGE
1985 && integer_zerop (vr1
.min
)
1986 && integer_zerop (vr1
.max
))))
1989 min
= max
= build_int_cst (expr_type
, 0);
1991 /* If one of the operands is one, we know that the whole
1992 expression evaluates one. */
1993 else if (code
== TRUTH_OR_EXPR
1994 && ((vr0
.type
== VR_RANGE
1995 && integer_onep (vr0
.min
)
1996 && integer_onep (vr0
.max
))
1997 || (vr1
.type
== VR_RANGE
1998 && integer_onep (vr1
.min
)
1999 && integer_onep (vr1
.max
))))
2002 min
= max
= build_int_cst (expr_type
, 1);
2004 else if (vr0
.type
!= VR_VARYING
2005 && vr1
.type
!= VR_VARYING
2006 && vr0
.type
== vr1
.type
2007 && !symbolic_range_p (&vr0
)
2008 && !overflow_infinity_range_p (&vr0
)
2009 && !symbolic_range_p (&vr1
)
2010 && !overflow_infinity_range_p (&vr1
))
2012 /* Boolean expressions cannot be folded with int_const_binop. */
2013 min
= fold_binary (code
, expr_type
, vr0
.min
, vr1
.min
);
2014 max
= fold_binary (code
, expr_type
, vr0
.max
, vr1
.max
);
2018 /* The result of a TRUTH_*_EXPR is always true or false. */
2019 set_value_range_to_truthvalue (vr
, expr_type
);
2023 else if (code
== PLUS_EXPR
2025 || code
== MAX_EXPR
)
2027 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
2028 VR_VARYING. It would take more effort to compute a precise
2029 range for such a case. For example, if we have op0 == 1 and
2030 op1 == -1 with their ranges both being ~[0,0], we would have
2031 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
2032 Note that we are guaranteed to have vr0.type == vr1.type at
2034 if (code
== PLUS_EXPR
&& vr0
.type
== VR_ANTI_RANGE
)
2036 set_value_range_to_varying (vr
);
2040 /* For operations that make the resulting range directly
2041 proportional to the original ranges, apply the operation to
2042 the same end of each range. */
2043 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
2044 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.max
);
2046 else if (code
== MULT_EXPR
2047 || code
== TRUNC_DIV_EXPR
2048 || code
== FLOOR_DIV_EXPR
2049 || code
== CEIL_DIV_EXPR
2050 || code
== EXACT_DIV_EXPR
2051 || code
== ROUND_DIV_EXPR
2052 || code
== RSHIFT_EXPR
)
2058 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
2059 drop to VR_VARYING. It would take more effort to compute a
2060 precise range for such a case. For example, if we have
2061 op0 == 65536 and op1 == 65536 with their ranges both being
2062 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
2063 we cannot claim that the product is in ~[0,0]. Note that we
2064 are guaranteed to have vr0.type == vr1.type at this
2066 if (code
== MULT_EXPR
2067 && vr0
.type
== VR_ANTI_RANGE
2068 && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0
)))
2070 set_value_range_to_varying (vr
);
2074 /* If we have a RSHIFT_EXPR with any shift values outside [0..prec-1],
2075 then drop to VR_VARYING. Outside of this range we get undefined
2076 behavior from the shift operation. We cannot even trust
2077 SHIFT_COUNT_TRUNCATED at this stage, because that applies to rtl
2078 shifts, and the operation at the tree level may be widened. */
2079 if (code
== RSHIFT_EXPR
)
2081 if (vr1
.type
== VR_ANTI_RANGE
2082 || !vrp_expr_computes_nonnegative (op1
, &sop
)
2084 (build_int_cst (TREE_TYPE (vr1
.max
),
2085 TYPE_PRECISION (expr_type
) - 1),
2088 set_value_range_to_varying (vr
);
2093 /* Multiplications and divisions are a bit tricky to handle,
2094 depending on the mix of signs we have in the two ranges, we
2095 need to operate on different values to get the minimum and
2096 maximum values for the new range. One approach is to figure
2097 out all the variations of range combinations and do the
2100 However, this involves several calls to compare_values and it
2101 is pretty convoluted. It's simpler to do the 4 operations
2102 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
2103 MAX1) and then figure the smallest and largest values to form
2106 /* Divisions by zero result in a VARYING value. */
2107 else if (code
!= MULT_EXPR
2108 && (vr0
.type
== VR_ANTI_RANGE
|| range_includes_zero_p (&vr1
)))
2110 set_value_range_to_varying (vr
);
2114 /* Compute the 4 cross operations. */
2116 val
[0] = vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
2117 if (val
[0] == NULL_TREE
)
2120 if (vr1
.max
== vr1
.min
)
2124 val
[1] = vrp_int_const_binop (code
, vr0
.min
, vr1
.max
);
2125 if (val
[1] == NULL_TREE
)
2129 if (vr0
.max
== vr0
.min
)
2133 val
[2] = vrp_int_const_binop (code
, vr0
.max
, vr1
.min
);
2134 if (val
[2] == NULL_TREE
)
2138 if (vr0
.min
== vr0
.max
|| vr1
.min
== vr1
.max
)
2142 val
[3] = vrp_int_const_binop (code
, vr0
.max
, vr1
.max
);
2143 if (val
[3] == NULL_TREE
)
2149 set_value_range_to_varying (vr
);
2153 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
2157 for (i
= 1; i
< 4; i
++)
2159 if (!is_gimple_min_invariant (min
)
2160 || (TREE_OVERFLOW (min
) && !is_overflow_infinity (min
))
2161 || !is_gimple_min_invariant (max
)
2162 || (TREE_OVERFLOW (max
) && !is_overflow_infinity (max
)))
2167 if (!is_gimple_min_invariant (val
[i
])
2168 || (TREE_OVERFLOW (val
[i
])
2169 && !is_overflow_infinity (val
[i
])))
2171 /* If we found an overflowed value, set MIN and MAX
2172 to it so that we set the resulting range to
2178 if (compare_values (val
[i
], min
) == -1)
2181 if (compare_values (val
[i
], max
) == 1)
2186 else if (code
== MINUS_EXPR
)
2188 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
2189 VR_VARYING. It would take more effort to compute a precise
2190 range for such a case. For example, if we have op0 == 1 and
2191 op1 == 1 with their ranges both being ~[0,0], we would have
2192 op0 - op1 == 0, so we cannot claim that the difference is in
2193 ~[0,0]. Note that we are guaranteed to have
2194 vr0.type == vr1.type at this point. */
2195 if (vr0
.type
== VR_ANTI_RANGE
)
2197 set_value_range_to_varying (vr
);
2201 /* For MINUS_EXPR, apply the operation to the opposite ends of
2203 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.max
);
2204 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.min
);
2206 else if (code
== BIT_AND_EXPR
)
2208 if (vr0
.type
== VR_RANGE
2209 && vr0
.min
== vr0
.max
2210 && TREE_CODE (vr0
.max
) == INTEGER_CST
2211 && !TREE_OVERFLOW (vr0
.max
)
2212 && tree_int_cst_sgn (vr0
.max
) >= 0)
2214 min
= build_int_cst (expr_type
, 0);
2217 else if (vr1
.type
== VR_RANGE
2218 && vr1
.min
== vr1
.max
2219 && TREE_CODE (vr1
.max
) == INTEGER_CST
2220 && !TREE_OVERFLOW (vr1
.max
)
2221 && tree_int_cst_sgn (vr1
.max
) >= 0)
2224 min
= build_int_cst (expr_type
, 0);
2229 set_value_range_to_varying (vr
);
2236 /* If either MIN or MAX overflowed, then set the resulting range to
2237 VARYING. But we do accept an overflow infinity
2239 if (min
== NULL_TREE
2240 || !is_gimple_min_invariant (min
)
2241 || (TREE_OVERFLOW (min
) && !is_overflow_infinity (min
))
2243 || !is_gimple_min_invariant (max
)
2244 || (TREE_OVERFLOW (max
) && !is_overflow_infinity (max
)))
2246 set_value_range_to_varying (vr
);
2252 2) [-INF, +-INF(OVF)]
2253 3) [+-INF(OVF), +INF]
2254 4) [+-INF(OVF), +-INF(OVF)]
2255 We learn nothing when we have INF and INF(OVF) on both sides.
2256 Note that we do accept [-INF, -INF] and [+INF, +INF] without
2258 if ((vrp_val_is_min (min
) || is_overflow_infinity (min
))
2259 && (vrp_val_is_max (max
) || is_overflow_infinity (max
)))
2261 set_value_range_to_varying (vr
);
2265 cmp
= compare_values (min
, max
);
2266 if (cmp
== -2 || cmp
== 1)
2268 /* If the new range has its limits swapped around (MIN > MAX),
2269 then the operation caused one of them to wrap around, mark
2270 the new range VARYING. */
2271 set_value_range_to_varying (vr
);
2274 set_value_range (vr
, type
, min
, max
, NULL
);
2278 /* Extract range information from a unary expression EXPR based on
2279 the range of its operand and the expression code. */
2282 extract_range_from_unary_expr (value_range_t
*vr
, enum tree_code code
,
2283 tree type
, tree op0
)
2287 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
2289 /* Refuse to operate on certain unary expressions for which we
2290 cannot easily determine a resulting range. */
2291 if (code
== FIX_TRUNC_EXPR
2292 || code
== FLOAT_EXPR
2293 || code
== BIT_NOT_EXPR
2294 || code
== CONJ_EXPR
)
2296 set_value_range_to_varying (vr
);
2300 /* Get value ranges for the operand. For constant operands, create
2301 a new value range with the operand to simplify processing. */
2302 if (TREE_CODE (op0
) == SSA_NAME
)
2303 vr0
= *(get_value_range (op0
));
2304 else if (is_gimple_min_invariant (op0
))
2305 set_value_range_to_value (&vr0
, op0
, NULL
);
2307 set_value_range_to_varying (&vr0
);
2309 /* If VR0 is UNDEFINED, so is the result. */
2310 if (vr0
.type
== VR_UNDEFINED
)
2312 set_value_range_to_undefined (vr
);
2316 /* Refuse to operate on symbolic ranges, or if neither operand is
2317 a pointer or integral type. */
2318 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
2319 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
2320 || (vr0
.type
!= VR_VARYING
2321 && symbolic_range_p (&vr0
)))
2323 set_value_range_to_varying (vr
);
2327 /* If the expression involves pointers, we are only interested in
2328 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
2329 if (POINTER_TYPE_P (type
) || POINTER_TYPE_P (TREE_TYPE (op0
)))
2334 if (range_is_nonnull (&vr0
)
2335 || (tree_unary_nonzero_warnv_p (code
, type
, op0
, &sop
)
2337 set_value_range_to_nonnull (vr
, type
);
2338 else if (range_is_null (&vr0
))
2339 set_value_range_to_null (vr
, type
);
2341 set_value_range_to_varying (vr
);
2346 /* Handle unary expressions on integer ranges. */
2347 if ((code
== NOP_EXPR
2348 || code
== CONVERT_EXPR
)
2349 && INTEGRAL_TYPE_P (type
)
2350 && INTEGRAL_TYPE_P (TREE_TYPE (op0
)))
2352 tree inner_type
= TREE_TYPE (op0
);
2353 tree outer_type
= type
;
2355 /* Always use base-types here. This is important for the
2356 correct signedness. */
2357 if (TREE_TYPE (inner_type
))
2358 inner_type
= TREE_TYPE (inner_type
);
2359 if (TREE_TYPE (outer_type
))
2360 outer_type
= TREE_TYPE (outer_type
);
2362 /* If VR0 is varying and we increase the type precision, assume
2363 a full range for the following transformation. */
2364 if (vr0
.type
== VR_VARYING
2365 && TYPE_PRECISION (inner_type
) < TYPE_PRECISION (outer_type
))
2367 vr0
.type
= VR_RANGE
;
2368 vr0
.min
= TYPE_MIN_VALUE (inner_type
);
2369 vr0
.max
= TYPE_MAX_VALUE (inner_type
);
2372 /* If VR0 is a constant range or anti-range and the conversion is
2373 not truncating we can convert the min and max values and
2374 canonicalize the resulting range. Otherwise we can do the
2375 conversion if the size of the range is less than what the
2376 precision of the target type can represent and the range is
2377 not an anti-range. */
2378 if ((vr0
.type
== VR_RANGE
2379 || vr0
.type
== VR_ANTI_RANGE
)
2380 && TREE_CODE (vr0
.min
) == INTEGER_CST
2381 && TREE_CODE (vr0
.max
) == INTEGER_CST
2382 && !is_overflow_infinity (vr0
.min
)
2383 && !is_overflow_infinity (vr0
.max
)
2384 && (TYPE_PRECISION (outer_type
) >= TYPE_PRECISION (inner_type
)
2385 || (vr0
.type
== VR_RANGE
2386 && integer_zerop (int_const_binop (RSHIFT_EXPR
,
2387 int_const_binop (MINUS_EXPR
, vr0
.max
, vr0
.min
, 0),
2388 size_int (TYPE_PRECISION (outer_type
)), 0)))))
2390 tree new_min
, new_max
;
2391 new_min
= force_fit_type_double (outer_type
,
2392 TREE_INT_CST_LOW (vr0
.min
),
2393 TREE_INT_CST_HIGH (vr0
.min
), 0, 0);
2394 new_max
= force_fit_type_double (outer_type
,
2395 TREE_INT_CST_LOW (vr0
.max
),
2396 TREE_INT_CST_HIGH (vr0
.max
), 0, 0);
2397 set_and_canonicalize_value_range (vr
, vr0
.type
,
2398 new_min
, new_max
, NULL
);
2402 set_value_range_to_varying (vr
);
2406 /* Conversion of a VR_VARYING value to a wider type can result
2407 in a usable range. So wait until after we've handled conversions
2408 before dropping the result to VR_VARYING if we had a source
2409 operand that is VR_VARYING. */
2410 if (vr0
.type
== VR_VARYING
)
2412 set_value_range_to_varying (vr
);
2416 /* Apply the operation to each end of the range and see what we end
2418 if (code
== NEGATE_EXPR
2419 && !TYPE_UNSIGNED (type
))
2421 /* NEGATE_EXPR flips the range around. We need to treat
2422 TYPE_MIN_VALUE specially. */
2423 if (is_positive_overflow_infinity (vr0
.max
))
2424 min
= negative_overflow_infinity (type
);
2425 else if (is_negative_overflow_infinity (vr0
.max
))
2426 min
= positive_overflow_infinity (type
);
2427 else if (!vrp_val_is_min (vr0
.max
))
2428 min
= fold_unary_to_constant (code
, type
, vr0
.max
);
2429 else if (needs_overflow_infinity (type
))
2431 if (supports_overflow_infinity (type
)
2432 && !is_overflow_infinity (vr0
.min
)
2433 && !vrp_val_is_min (vr0
.min
))
2434 min
= positive_overflow_infinity (type
);
2437 set_value_range_to_varying (vr
);
2442 min
= TYPE_MIN_VALUE (type
);
2444 if (is_positive_overflow_infinity (vr0
.min
))
2445 max
= negative_overflow_infinity (type
);
2446 else if (is_negative_overflow_infinity (vr0
.min
))
2447 max
= positive_overflow_infinity (type
);
2448 else if (!vrp_val_is_min (vr0
.min
))
2449 max
= fold_unary_to_constant (code
, type
, vr0
.min
);
2450 else if (needs_overflow_infinity (type
))
2452 if (supports_overflow_infinity (type
))
2453 max
= positive_overflow_infinity (type
);
2456 set_value_range_to_varying (vr
);
2461 max
= TYPE_MIN_VALUE (type
);
2463 else if (code
== NEGATE_EXPR
2464 && TYPE_UNSIGNED (type
))
2466 if (!range_includes_zero_p (&vr0
))
2468 max
= fold_unary_to_constant (code
, type
, vr0
.min
);
2469 min
= fold_unary_to_constant (code
, type
, vr0
.max
);
2473 if (range_is_null (&vr0
))
2474 set_value_range_to_null (vr
, type
);
2476 set_value_range_to_varying (vr
);
2480 else if (code
== ABS_EXPR
2481 && !TYPE_UNSIGNED (type
))
2483 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
2485 if (!TYPE_OVERFLOW_UNDEFINED (type
)
2486 && ((vr0
.type
== VR_RANGE
2487 && vrp_val_is_min (vr0
.min
))
2488 || (vr0
.type
== VR_ANTI_RANGE
2489 && !vrp_val_is_min (vr0
.min
)
2490 && !range_includes_zero_p (&vr0
))))
2492 set_value_range_to_varying (vr
);
2496 /* ABS_EXPR may flip the range around, if the original range
2497 included negative values. */
2498 if (is_overflow_infinity (vr0
.min
))
2499 min
= positive_overflow_infinity (type
);
2500 else if (!vrp_val_is_min (vr0
.min
))
2501 min
= fold_unary_to_constant (code
, type
, vr0
.min
);
2502 else if (!needs_overflow_infinity (type
))
2503 min
= TYPE_MAX_VALUE (type
);
2504 else if (supports_overflow_infinity (type
))
2505 min
= positive_overflow_infinity (type
);
2508 set_value_range_to_varying (vr
);
2512 if (is_overflow_infinity (vr0
.max
))
2513 max
= positive_overflow_infinity (type
);
2514 else if (!vrp_val_is_min (vr0
.max
))
2515 max
= fold_unary_to_constant (code
, type
, vr0
.max
);
2516 else if (!needs_overflow_infinity (type
))
2517 max
= TYPE_MAX_VALUE (type
);
2518 else if (supports_overflow_infinity (type
))
2519 max
= positive_overflow_infinity (type
);
2522 set_value_range_to_varying (vr
);
2526 cmp
= compare_values (min
, max
);
2528 /* If a VR_ANTI_RANGEs contains zero, then we have
2529 ~[-INF, min(MIN, MAX)]. */
2530 if (vr0
.type
== VR_ANTI_RANGE
)
2532 if (range_includes_zero_p (&vr0
))
2534 /* Take the lower of the two values. */
2538 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
2539 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
2540 flag_wrapv is set and the original anti-range doesn't include
2541 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
2542 if (TYPE_OVERFLOW_WRAPS (type
))
2544 tree type_min_value
= TYPE_MIN_VALUE (type
);
2546 min
= (vr0
.min
!= type_min_value
2547 ? int_const_binop (PLUS_EXPR
, type_min_value
,
2548 integer_one_node
, 0)
2553 if (overflow_infinity_range_p (&vr0
))
2554 min
= negative_overflow_infinity (type
);
2556 min
= TYPE_MIN_VALUE (type
);
2561 /* All else has failed, so create the range [0, INF], even for
2562 flag_wrapv since TYPE_MIN_VALUE is in the original
2564 vr0
.type
= VR_RANGE
;
2565 min
= build_int_cst (type
, 0);
2566 if (needs_overflow_infinity (type
))
2568 if (supports_overflow_infinity (type
))
2569 max
= positive_overflow_infinity (type
);
2572 set_value_range_to_varying (vr
);
2577 max
= TYPE_MAX_VALUE (type
);
2581 /* If the range contains zero then we know that the minimum value in the
2582 range will be zero. */
2583 else if (range_includes_zero_p (&vr0
))
2587 min
= build_int_cst (type
, 0);
2591 /* If the range was reversed, swap MIN and MAX. */
2602 /* Otherwise, operate on each end of the range. */
2603 min
= fold_unary_to_constant (code
, type
, vr0
.min
);
2604 max
= fold_unary_to_constant (code
, type
, vr0
.max
);
2606 if (needs_overflow_infinity (type
))
2608 gcc_assert (code
!= NEGATE_EXPR
&& code
!= ABS_EXPR
);
2610 /* If both sides have overflowed, we don't know
2612 if ((is_overflow_infinity (vr0
.min
)
2613 || TREE_OVERFLOW (min
))
2614 && (is_overflow_infinity (vr0
.max
)
2615 || TREE_OVERFLOW (max
)))
2617 set_value_range_to_varying (vr
);
2621 if (is_overflow_infinity (vr0
.min
))
2623 else if (TREE_OVERFLOW (min
))
2625 if (supports_overflow_infinity (type
))
2626 min
= (tree_int_cst_sgn (min
) >= 0
2627 ? positive_overflow_infinity (TREE_TYPE (min
))
2628 : negative_overflow_infinity (TREE_TYPE (min
)));
2631 set_value_range_to_varying (vr
);
2636 if (is_overflow_infinity (vr0
.max
))
2638 else if (TREE_OVERFLOW (max
))
2640 if (supports_overflow_infinity (type
))
2641 max
= (tree_int_cst_sgn (max
) >= 0
2642 ? positive_overflow_infinity (TREE_TYPE (max
))
2643 : negative_overflow_infinity (TREE_TYPE (max
)));
2646 set_value_range_to_varying (vr
);
2653 cmp
= compare_values (min
, max
);
2654 if (cmp
== -2 || cmp
== 1)
2656 /* If the new range has its limits swapped around (MIN > MAX),
2657 then the operation caused one of them to wrap around, mark
2658 the new range VARYING. */
2659 set_value_range_to_varying (vr
);
2662 set_value_range (vr
, vr0
.type
, min
, max
, NULL
);
2666 /* Extract range information from a conditional expression EXPR based on
2667 the ranges of each of its operands and the expression code. */
2670 extract_range_from_cond_expr (value_range_t
*vr
, tree expr
)
2673 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
2674 value_range_t vr1
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
2676 /* Get value ranges for each operand. For constant operands, create
2677 a new value range with the operand to simplify processing. */
2678 op0
= COND_EXPR_THEN (expr
);
2679 if (TREE_CODE (op0
) == SSA_NAME
)
2680 vr0
= *(get_value_range (op0
));
2681 else if (is_gimple_min_invariant (op0
))
2682 set_value_range_to_value (&vr0
, op0
, NULL
);
2684 set_value_range_to_varying (&vr0
);
2686 op1
= COND_EXPR_ELSE (expr
);
2687 if (TREE_CODE (op1
) == SSA_NAME
)
2688 vr1
= *(get_value_range (op1
));
2689 else if (is_gimple_min_invariant (op1
))
2690 set_value_range_to_value (&vr1
, op1
, NULL
);
2692 set_value_range_to_varying (&vr1
);
2694 /* The resulting value range is the union of the operand ranges */
2695 vrp_meet (&vr0
, &vr1
);
2696 copy_value_range (vr
, &vr0
);
2700 /* Extract range information from a comparison expression EXPR based
2701 on the range of its operand and the expression code. */
2704 extract_range_from_comparison (value_range_t
*vr
, enum tree_code code
,
2705 tree type
, tree op0
, tree op1
)
2708 tree val
= vrp_evaluate_conditional_warnv_with_ops (code
,
2713 /* A disadvantage of using a special infinity as an overflow
2714 representation is that we lose the ability to record overflow
2715 when we don't have an infinity. So we have to ignore a result
2716 which relies on overflow. */
2718 if (val
&& !is_overflow_infinity (val
) && !sop
)
2720 /* Since this expression was found on the RHS of an assignment,
2721 its type may be different from _Bool. Convert VAL to EXPR's
2723 val
= fold_convert (type
, val
);
2724 if (is_gimple_min_invariant (val
))
2725 set_value_range_to_value (vr
, val
, vr
->equiv
);
2727 set_value_range (vr
, VR_RANGE
, val
, val
, vr
->equiv
);
2730 /* The result of a comparison is always true or false. */
2731 set_value_range_to_truthvalue (vr
, type
);
2735 /* Try to compute a useful range out of expression EXPR and store it
2739 extract_range_from_expr (value_range_t
*vr
, tree expr
)
2741 enum tree_code code
= TREE_CODE (expr
);
2743 if (code
== ASSERT_EXPR
)
2744 extract_range_from_assert (vr
, expr
);
2745 else if (code
== SSA_NAME
)
2746 extract_range_from_ssa_name (vr
, expr
);
2747 else if (TREE_CODE_CLASS (code
) == tcc_binary
2748 || code
== TRUTH_AND_EXPR
2749 || code
== TRUTH_OR_EXPR
2750 || code
== TRUTH_XOR_EXPR
)
2751 extract_range_from_binary_expr (vr
, TREE_CODE (expr
), TREE_TYPE (expr
),
2752 TREE_OPERAND (expr
, 0),
2753 TREE_OPERAND (expr
, 1));
2754 else if (TREE_CODE_CLASS (code
) == tcc_unary
)
2755 extract_range_from_unary_expr (vr
, TREE_CODE (expr
), TREE_TYPE (expr
),
2756 TREE_OPERAND (expr
, 0));
2757 else if (code
== COND_EXPR
)
2758 extract_range_from_cond_expr (vr
, expr
);
2759 else if (TREE_CODE_CLASS (code
) == tcc_comparison
)
2760 extract_range_from_comparison (vr
, TREE_CODE (expr
), TREE_TYPE (expr
),
2761 TREE_OPERAND (expr
, 0),
2762 TREE_OPERAND (expr
, 1));
2763 else if (is_gimple_min_invariant (expr
))
2764 set_value_range_to_value (vr
, expr
, NULL
);
2766 set_value_range_to_varying (vr
);
2768 /* If we got a varying range from the tests above, try a final
2769 time to derive a nonnegative or nonzero range. This time
2770 relying primarily on generic routines in fold in conjunction
2772 if (vr
->type
== VR_VARYING
)
2776 if (INTEGRAL_TYPE_P (TREE_TYPE (expr
))
2777 && vrp_expr_computes_nonnegative (expr
, &sop
))
2778 set_value_range_to_nonnegative (vr
, TREE_TYPE (expr
),
2779 sop
|| is_overflow_infinity (expr
));
2780 else if (vrp_expr_computes_nonzero (expr
, &sop
)
2782 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
2786 /* Given a range VR, a LOOP and a variable VAR, determine whether it
2787 would be profitable to adjust VR using scalar evolution information
2788 for VAR. If so, update VR with the new limits. */
2791 adjust_range_with_scev (value_range_t
*vr
, struct loop
*loop
, tree stmt
,
2794 tree init
, step
, chrec
, tmin
, tmax
, min
, max
, type
;
2795 enum ev_direction dir
;
2797 /* TODO. Don't adjust anti-ranges. An anti-range may provide
2798 better opportunities than a regular range, but I'm not sure. */
2799 if (vr
->type
== VR_ANTI_RANGE
)
2802 /* Ensure that there are not values in the scev cache based on assumptions
2803 on ranges of ssa names that were changed
2804 (in set_value_range/set_value_range_to_varying). Preserve cached numbers
2805 of iterations, that were computed before the start of VRP (we do not
2806 recompute these each time to save the compile time). */
2807 scev_reset_except_niters ();
2809 chrec
= instantiate_parameters (loop
, analyze_scalar_evolution (loop
, var
));
2811 /* Like in PR19590, scev can return a constant function. */
2812 if (is_gimple_min_invariant (chrec
))
2814 set_value_range_to_value (vr
, chrec
, vr
->equiv
);
2818 if (TREE_CODE (chrec
) != POLYNOMIAL_CHREC
)
2821 init
= initial_condition_in_loop_num (chrec
, loop
->num
);
2822 step
= evolution_part_in_loop_num (chrec
, loop
->num
);
2824 /* If STEP is symbolic, we can't know whether INIT will be the
2825 minimum or maximum value in the range. Also, unless INIT is
2826 a simple expression, compare_values and possibly other functions
2827 in tree-vrp won't be able to handle it. */
2828 if (step
== NULL_TREE
2829 || !is_gimple_min_invariant (step
)
2830 || !valid_value_p (init
))
2833 dir
= scev_direction (chrec
);
2834 if (/* Do not adjust ranges if we do not know whether the iv increases
2835 or decreases, ... */
2836 dir
== EV_DIR_UNKNOWN
2837 /* ... or if it may wrap. */
2838 || scev_probably_wraps_p (init
, step
, stmt
, get_chrec_loop (chrec
),
2842 /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of
2843 negative_overflow_infinity and positive_overflow_infinity,
2844 because we have concluded that the loop probably does not
2847 type
= TREE_TYPE (var
);
2848 if (POINTER_TYPE_P (type
) || !TYPE_MIN_VALUE (type
))
2849 tmin
= lower_bound_in_type (type
, type
);
2851 tmin
= TYPE_MIN_VALUE (type
);
2852 if (POINTER_TYPE_P (type
) || !TYPE_MAX_VALUE (type
))
2853 tmax
= upper_bound_in_type (type
, type
);
2855 tmax
= TYPE_MAX_VALUE (type
);
2857 if (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
)
2862 /* For VARYING or UNDEFINED ranges, just about anything we get
2863 from scalar evolutions should be better. */
2865 if (dir
== EV_DIR_DECREASES
)
2870 /* If we would create an invalid range, then just assume we
2871 know absolutely nothing. This may be over-conservative,
2872 but it's clearly safe, and should happen only in unreachable
2873 parts of code, or for invalid programs. */
2874 if (compare_values (min
, max
) == 1)
2877 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
2879 else if (vr
->type
== VR_RANGE
)
2884 if (dir
== EV_DIR_DECREASES
)
2886 /* INIT is the maximum value. If INIT is lower than VR->MAX
2887 but no smaller than VR->MIN, set VR->MAX to INIT. */
2888 if (compare_values (init
, max
) == -1)
2892 /* If we just created an invalid range with the minimum
2893 greater than the maximum, we fail conservatively.
2894 This should happen only in unreachable
2895 parts of code, or for invalid programs. */
2896 if (compare_values (min
, max
) == 1)
2900 /* According to the loop information, the variable does not
2901 overflow. If we think it does, probably because of an
2902 overflow due to arithmetic on a different INF value,
2904 if (is_negative_overflow_infinity (min
))
2909 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2910 if (compare_values (init
, min
) == 1)
2914 /* Again, avoid creating invalid range by failing. */
2915 if (compare_values (min
, max
) == 1)
2919 if (is_positive_overflow_infinity (max
))
2923 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
2927 /* Return true if VAR may overflow at STMT. This checks any available
2928 loop information to see if we can determine that VAR does not
2932 vrp_var_may_overflow (tree var
, tree stmt
)
2935 tree chrec
, init
, step
;
2937 if (current_loops
== NULL
)
2940 l
= loop_containing_stmt (stmt
);
2944 chrec
= instantiate_parameters (l
, analyze_scalar_evolution (l
, var
));
2945 if (TREE_CODE (chrec
) != POLYNOMIAL_CHREC
)
2948 init
= initial_condition_in_loop_num (chrec
, l
->num
);
2949 step
= evolution_part_in_loop_num (chrec
, l
->num
);
2951 if (step
== NULL_TREE
2952 || !is_gimple_min_invariant (step
)
2953 || !valid_value_p (init
))
2956 /* If we get here, we know something useful about VAR based on the
2957 loop information. If it wraps, it may overflow. */
2959 if (scev_probably_wraps_p (init
, step
, stmt
, get_chrec_loop (chrec
),
2963 if (dump_file
&& (dump_flags
& TDF_DETAILS
) != 0)
2965 print_generic_expr (dump_file
, var
, 0);
2966 fprintf (dump_file
, ": loop information indicates does not overflow\n");
2973 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2975 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2976 all the values in the ranges.
2978 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2980 - Return NULL_TREE if it is not always possible to determine the
2981 value of the comparison.
2983 Also set *STRICT_OVERFLOW_P to indicate whether a range with an
2984 overflow infinity was used in the test. */
2988 compare_ranges (enum tree_code comp
, value_range_t
*vr0
, value_range_t
*vr1
,
2989 bool *strict_overflow_p
)
2991 /* VARYING or UNDEFINED ranges cannot be compared. */
2992 if (vr0
->type
== VR_VARYING
2993 || vr0
->type
== VR_UNDEFINED
2994 || vr1
->type
== VR_VARYING
2995 || vr1
->type
== VR_UNDEFINED
)
2998 /* Anti-ranges need to be handled separately. */
2999 if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
3001 /* If both are anti-ranges, then we cannot compute any
3003 if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
3006 /* These comparisons are never statically computable. */
3013 /* Equality can be computed only between a range and an
3014 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
3015 if (vr0
->type
== VR_RANGE
)
3017 /* To simplify processing, make VR0 the anti-range. */
3018 value_range_t
*tmp
= vr0
;
3023 gcc_assert (comp
== NE_EXPR
|| comp
== EQ_EXPR
);
3025 if (compare_values_warnv (vr0
->min
, vr1
->min
, strict_overflow_p
) == 0
3026 && compare_values_warnv (vr0
->max
, vr1
->max
, strict_overflow_p
) == 0)
3027 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
3032 if (!usable_range_p (vr0
, strict_overflow_p
)
3033 || !usable_range_p (vr1
, strict_overflow_p
))
3036 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
3037 operands around and change the comparison code. */
3038 if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
3041 comp
= (comp
== GT_EXPR
) ? LT_EXPR
: LE_EXPR
;
3047 if (comp
== EQ_EXPR
)
3049 /* Equality may only be computed if both ranges represent
3050 exactly one value. */
3051 if (compare_values_warnv (vr0
->min
, vr0
->max
, strict_overflow_p
) == 0
3052 && compare_values_warnv (vr1
->min
, vr1
->max
, strict_overflow_p
) == 0)
3054 int cmp_min
= compare_values_warnv (vr0
->min
, vr1
->min
,
3056 int cmp_max
= compare_values_warnv (vr0
->max
, vr1
->max
,
3058 if (cmp_min
== 0 && cmp_max
== 0)
3059 return boolean_true_node
;
3060 else if (cmp_min
!= -2 && cmp_max
!= -2)
3061 return boolean_false_node
;
3063 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
3064 else if (compare_values_warnv (vr0
->min
, vr1
->max
,
3065 strict_overflow_p
) == 1
3066 || compare_values_warnv (vr1
->min
, vr0
->max
,
3067 strict_overflow_p
) == 1)
3068 return boolean_false_node
;
3072 else if (comp
== NE_EXPR
)
3076 /* If VR0 is completely to the left or completely to the right
3077 of VR1, they are always different. Notice that we need to
3078 make sure that both comparisons yield similar results to
3079 avoid comparing values that cannot be compared at
3081 cmp1
= compare_values_warnv (vr0
->max
, vr1
->min
, strict_overflow_p
);
3082 cmp2
= compare_values_warnv (vr0
->min
, vr1
->max
, strict_overflow_p
);
3083 if ((cmp1
== -1 && cmp2
== -1) || (cmp1
== 1 && cmp2
== 1))
3084 return boolean_true_node
;
3086 /* If VR0 and VR1 represent a single value and are identical,
3088 else if (compare_values_warnv (vr0
->min
, vr0
->max
,
3089 strict_overflow_p
) == 0
3090 && compare_values_warnv (vr1
->min
, vr1
->max
,
3091 strict_overflow_p
) == 0
3092 && compare_values_warnv (vr0
->min
, vr1
->min
,
3093 strict_overflow_p
) == 0
3094 && compare_values_warnv (vr0
->max
, vr1
->max
,
3095 strict_overflow_p
) == 0)
3096 return boolean_false_node
;
3098 /* Otherwise, they may or may not be different. */
3102 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
3106 /* If VR0 is to the left of VR1, return true. */
3107 tst
= compare_values_warnv (vr0
->max
, vr1
->min
, strict_overflow_p
);
3108 if ((comp
== LT_EXPR
&& tst
== -1)
3109 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
3111 if (overflow_infinity_range_p (vr0
)
3112 || overflow_infinity_range_p (vr1
))
3113 *strict_overflow_p
= true;
3114 return boolean_true_node
;
3117 /* If VR0 is to the right of VR1, return false. */
3118 tst
= compare_values_warnv (vr0
->min
, vr1
->max
, strict_overflow_p
);
3119 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
3120 || (comp
== LE_EXPR
&& tst
== 1))
3122 if (overflow_infinity_range_p (vr0
)
3123 || overflow_infinity_range_p (vr1
))
3124 *strict_overflow_p
= true;
3125 return boolean_false_node
;
3128 /* Otherwise, we don't know. */
3136 /* Given a value range VR, a value VAL and a comparison code COMP, return
3137 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
3138 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
3139 always returns false. Return NULL_TREE if it is not always
3140 possible to determine the value of the comparison. Also set
3141 *STRICT_OVERFLOW_P to indicate whether a range with an overflow
3142 infinity was used in the test. */
3145 compare_range_with_value (enum tree_code comp
, value_range_t
*vr
, tree val
,
3146 bool *strict_overflow_p
)
3148 if (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
)
3151 /* Anti-ranges need to be handled separately. */
3152 if (vr
->type
== VR_ANTI_RANGE
)
3154 /* For anti-ranges, the only predicates that we can compute at
3155 compile time are equality and inequality. */
3162 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
3163 if (value_inside_range (val
, vr
) == 1)
3164 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
3169 if (!usable_range_p (vr
, strict_overflow_p
))
3172 if (comp
== EQ_EXPR
)
3174 /* EQ_EXPR may only be computed if VR represents exactly
3176 if (compare_values_warnv (vr
->min
, vr
->max
, strict_overflow_p
) == 0)
3178 int cmp
= compare_values_warnv (vr
->min
, val
, strict_overflow_p
);
3180 return boolean_true_node
;
3181 else if (cmp
== -1 || cmp
== 1 || cmp
== 2)
3182 return boolean_false_node
;
3184 else if (compare_values_warnv (val
, vr
->min
, strict_overflow_p
) == -1
3185 || compare_values_warnv (vr
->max
, val
, strict_overflow_p
) == -1)
3186 return boolean_false_node
;
3190 else if (comp
== NE_EXPR
)
3192 /* If VAL is not inside VR, then they are always different. */
3193 if (compare_values_warnv (vr
->max
, val
, strict_overflow_p
) == -1
3194 || compare_values_warnv (vr
->min
, val
, strict_overflow_p
) == 1)
3195 return boolean_true_node
;
3197 /* If VR represents exactly one value equal to VAL, then return
3199 if (compare_values_warnv (vr
->min
, vr
->max
, strict_overflow_p
) == 0
3200 && compare_values_warnv (vr
->min
, val
, strict_overflow_p
) == 0)
3201 return boolean_false_node
;
3203 /* Otherwise, they may or may not be different. */
3206 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
3210 /* If VR is to the left of VAL, return true. */
3211 tst
= compare_values_warnv (vr
->max
, val
, strict_overflow_p
);
3212 if ((comp
== LT_EXPR
&& tst
== -1)
3213 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
3215 if (overflow_infinity_range_p (vr
))
3216 *strict_overflow_p
= true;
3217 return boolean_true_node
;
3220 /* If VR is to the right of VAL, return false. */
3221 tst
= compare_values_warnv (vr
->min
, val
, strict_overflow_p
);
3222 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
3223 || (comp
== LE_EXPR
&& tst
== 1))
3225 if (overflow_infinity_range_p (vr
))
3226 *strict_overflow_p
= true;
3227 return boolean_false_node
;
3230 /* Otherwise, we don't know. */
3233 else if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
3237 /* If VR is to the right of VAL, return true. */
3238 tst
= compare_values_warnv (vr
->min
, val
, strict_overflow_p
);
3239 if ((comp
== GT_EXPR
&& tst
== 1)
3240 || (comp
== GE_EXPR
&& (tst
== 0 || tst
== 1)))
3242 if (overflow_infinity_range_p (vr
))
3243 *strict_overflow_p
= true;
3244 return boolean_true_node
;
3247 /* If VR is to the left of VAL, return false. */
3248 tst
= compare_values_warnv (vr
->max
, val
, strict_overflow_p
);
3249 if ((comp
== GT_EXPR
&& (tst
== -1 || tst
== 0))
3250 || (comp
== GE_EXPR
&& tst
== -1))
3252 if (overflow_infinity_range_p (vr
))
3253 *strict_overflow_p
= true;
3254 return boolean_false_node
;
3257 /* Otherwise, we don't know. */
3265 /* Debugging dumps. */
3267 void dump_value_range (FILE *, value_range_t
*);
3268 void debug_value_range (value_range_t
*);
3269 void dump_all_value_ranges (FILE *);
3270 void debug_all_value_ranges (void);
3271 void dump_vr_equiv (FILE *, bitmap
);
3272 void debug_vr_equiv (bitmap
);
3275 /* Dump value range VR to FILE. */
3278 dump_value_range (FILE *file
, value_range_t
*vr
)
3281 fprintf (file
, "[]");
3282 else if (vr
->type
== VR_UNDEFINED
)
3283 fprintf (file
, "UNDEFINED");
3284 else if (vr
->type
== VR_RANGE
|| vr
->type
== VR_ANTI_RANGE
)
3286 tree type
= TREE_TYPE (vr
->min
);
3288 fprintf (file
, "%s[", (vr
->type
== VR_ANTI_RANGE
) ? "~" : "");
3290 if (is_negative_overflow_infinity (vr
->min
))
3291 fprintf (file
, "-INF(OVF)");
3292 else if (INTEGRAL_TYPE_P (type
)
3293 && !TYPE_UNSIGNED (type
)
3294 && vrp_val_is_min (vr
->min
))
3295 fprintf (file
, "-INF");
3297 print_generic_expr (file
, vr
->min
, 0);
3299 fprintf (file
, ", ");
3301 if (is_positive_overflow_infinity (vr
->max
))
3302 fprintf (file
, "+INF(OVF)");
3303 else if (INTEGRAL_TYPE_P (type
)
3304 && vrp_val_is_max (vr
->max
))
3305 fprintf (file
, "+INF");
3307 print_generic_expr (file
, vr
->max
, 0);
3309 fprintf (file
, "]");
3316 fprintf (file
, " EQUIVALENCES: { ");
3318 EXECUTE_IF_SET_IN_BITMAP (vr
->equiv
, 0, i
, bi
)
3320 print_generic_expr (file
, ssa_name (i
), 0);
3321 fprintf (file
, " ");
3325 fprintf (file
, "} (%u elements)", c
);
3328 else if (vr
->type
== VR_VARYING
)
3329 fprintf (file
, "VARYING");
3331 fprintf (file
, "INVALID RANGE");
3335 /* Dump value range VR to stderr. */
3338 debug_value_range (value_range_t
*vr
)
3340 dump_value_range (stderr
, vr
);
3341 fprintf (stderr
, "\n");
3345 /* Dump value ranges of all SSA_NAMEs to FILE. */
3348 dump_all_value_ranges (FILE *file
)
3352 for (i
= 0; i
< num_ssa_names
; i
++)
3356 print_generic_expr (file
, ssa_name (i
), 0);
3357 fprintf (file
, ": ");
3358 dump_value_range (file
, vr_value
[i
]);
3359 fprintf (file
, "\n");
3363 fprintf (file
, "\n");
3367 /* Dump all value ranges to stderr. */
3370 debug_all_value_ranges (void)
3372 dump_all_value_ranges (stderr
);
3376 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
3377 create a new SSA name N and return the assertion assignment
3378 'V = ASSERT_EXPR <V, V OP W>'. */
3381 build_assert_expr_for (tree cond
, tree v
)
3385 gcc_assert (TREE_CODE (v
) == SSA_NAME
);
3386 n
= duplicate_ssa_name (v
, NULL_TREE
);
3388 if (COMPARISON_CLASS_P (cond
))
3390 tree a
= build2 (ASSERT_EXPR
, TREE_TYPE (v
), v
, cond
);
3391 assertion
= build_gimple_modify_stmt (n
, a
);
3393 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
)
3395 /* Given !V, build the assignment N = false. */
3396 tree op0
= TREE_OPERAND (cond
, 0);
3397 gcc_assert (op0
== v
);
3398 assertion
= build_gimple_modify_stmt (n
, boolean_false_node
);
3400 else if (TREE_CODE (cond
) == SSA_NAME
)
3402 /* Given V, build the assignment N = true. */
3403 gcc_assert (v
== cond
);
3404 assertion
= build_gimple_modify_stmt (n
, boolean_true_node
);
3409 SSA_NAME_DEF_STMT (n
) = assertion
;
3411 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
3412 operand of the ASSERT_EXPR. Register the new name and the old one
3413 in the replacement table so that we can fix the SSA web after
3414 adding all the ASSERT_EXPRs. */
3415 register_new_name_mapping (n
, v
);
3421 /* Return false if EXPR is a predicate expression involving floating
3425 fp_predicate (const_tree expr
)
3427 return (COMPARISON_CLASS_P (expr
)
3428 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr
, 0))));
3432 /* If the range of values taken by OP can be inferred after STMT executes,
3433 return the comparison code (COMP_CODE_P) and value (VAL_P) that
3434 describes the inferred range. Return true if a range could be
3438 infer_value_range (tree stmt
, tree op
, enum tree_code
*comp_code_p
, tree
*val_p
)
3441 *comp_code_p
= ERROR_MARK
;
3443 /* Do not attempt to infer anything in names that flow through
3445 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op
))
3448 /* Similarly, don't infer anything from statements that may throw
3450 if (tree_could_throw_p (stmt
))
3453 /* If STMT is the last statement of a basic block with no
3454 successors, there is no point inferring anything about any of its
3455 operands. We would not be able to find a proper insertion point
3456 for the assertion, anyway. */
3457 if (stmt_ends_bb_p (stmt
) && EDGE_COUNT (bb_for_stmt (stmt
)->succs
) == 0)
3460 /* We can only assume that a pointer dereference will yield
3461 non-NULL if -fdelete-null-pointer-checks is enabled. */
3462 if (flag_delete_null_pointer_checks
&& POINTER_TYPE_P (TREE_TYPE (op
)))
3464 unsigned num_uses
, num_loads
, num_stores
;
3466 count_uses_and_derefs (op
, stmt
, &num_uses
, &num_loads
, &num_stores
);
3467 if (num_loads
+ num_stores
> 0)
3469 *val_p
= build_int_cst (TREE_TYPE (op
), 0);
3470 *comp_code_p
= NE_EXPR
;
3479 void dump_asserts_for (FILE *, tree
);
3480 void debug_asserts_for (tree
);
3481 void dump_all_asserts (FILE *);
3482 void debug_all_asserts (void);
3484 /* Dump all the registered assertions for NAME to FILE. */
3487 dump_asserts_for (FILE *file
, tree name
)
3491 fprintf (file
, "Assertions to be inserted for ");
3492 print_generic_expr (file
, name
, 0);
3493 fprintf (file
, "\n");
3495 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
3498 fprintf (file
, "\t");
3499 print_generic_expr (file
, bsi_stmt (loc
->si
), 0);
3500 fprintf (file
, "\n\tBB #%d", loc
->bb
->index
);
3503 fprintf (file
, "\n\tEDGE %d->%d", loc
->e
->src
->index
,
3504 loc
->e
->dest
->index
);
3505 dump_edge_info (file
, loc
->e
, 0);
3507 fprintf (file
, "\n\tPREDICATE: ");
3508 print_generic_expr (file
, name
, 0);
3509 fprintf (file
, " %s ", tree_code_name
[(int)loc
->comp_code
]);
3510 print_generic_expr (file
, loc
->val
, 0);
3511 fprintf (file
, "\n\n");
3515 fprintf (file
, "\n");
3519 /* Dump all the registered assertions for NAME to stderr. */
3522 debug_asserts_for (tree name
)
3524 dump_asserts_for (stderr
, name
);
3528 /* Dump all the registered assertions for all the names to FILE. */
3531 dump_all_asserts (FILE *file
)
3536 fprintf (file
, "\nASSERT_EXPRs to be inserted\n\n");
3537 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
3538 dump_asserts_for (file
, ssa_name (i
));
3539 fprintf (file
, "\n");
3543 /* Dump all the registered assertions for all the names to stderr. */
3546 debug_all_asserts (void)
3548 dump_all_asserts (stderr
);
3552 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
3553 'EXPR COMP_CODE VAL' at a location that dominates block BB or
3554 E->DEST, then register this location as a possible insertion point
3555 for ASSERT_EXPR <NAME, EXPR COMP_CODE VAL>.
3557 BB, E and SI provide the exact insertion point for the new
3558 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
3559 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
3560 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
3561 must not be NULL. */
3564 register_new_assert_for (tree name
, tree expr
,
3565 enum tree_code comp_code
,
3569 block_stmt_iterator si
)
3571 assert_locus_t n
, loc
, last_loc
;
3573 basic_block dest_bb
;
3575 #if defined ENABLE_CHECKING
3576 gcc_assert (bb
== NULL
|| e
== NULL
);
3579 gcc_assert (TREE_CODE (bsi_stmt (si
)) != COND_EXPR
3580 && TREE_CODE (bsi_stmt (si
)) != SWITCH_EXPR
);
3583 /* The new assertion A will be inserted at BB or E. We need to
3584 determine if the new location is dominated by a previously
3585 registered location for A. If we are doing an edge insertion,
3586 assume that A will be inserted at E->DEST. Note that this is not
3589 If E is a critical edge, it will be split. But even if E is
3590 split, the new block will dominate the same set of blocks that
3593 The reverse, however, is not true, blocks dominated by E->DEST
3594 will not be dominated by the new block created to split E. So,
3595 if the insertion location is on a critical edge, we will not use
3596 the new location to move another assertion previously registered
3597 at a block dominated by E->DEST. */
3598 dest_bb
= (bb
) ? bb
: e
->dest
;
3600 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
3601 VAL at a block dominating DEST_BB, then we don't need to insert a new
3602 one. Similarly, if the same assertion already exists at a block
3603 dominated by DEST_BB and the new location is not on a critical
3604 edge, then update the existing location for the assertion (i.e.,
3605 move the assertion up in the dominance tree).
3607 Note, this is implemented as a simple linked list because there
3608 should not be more than a handful of assertions registered per
3609 name. If this becomes a performance problem, a table hashed by
3610 COMP_CODE and VAL could be implemented. */
3611 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
3616 if (loc
->comp_code
== comp_code
3618 || operand_equal_p (loc
->val
, val
, 0))
3619 && (loc
->expr
== expr
3620 || operand_equal_p (loc
->expr
, expr
, 0)))
3622 /* If the assertion NAME COMP_CODE VAL has already been
3623 registered at a basic block that dominates DEST_BB, then
3624 we don't need to insert the same assertion again. Note
3625 that we don't check strict dominance here to avoid
3626 replicating the same assertion inside the same basic
3627 block more than once (e.g., when a pointer is
3628 dereferenced several times inside a block).
3630 An exception to this rule are edge insertions. If the
3631 new assertion is to be inserted on edge E, then it will
3632 dominate all the other insertions that we may want to
3633 insert in DEST_BB. So, if we are doing an edge
3634 insertion, don't do this dominance check. */
3636 && dominated_by_p (CDI_DOMINATORS
, dest_bb
, loc
->bb
))
3639 /* Otherwise, if E is not a critical edge and DEST_BB
3640 dominates the existing location for the assertion, move
3641 the assertion up in the dominance tree by updating its
3642 location information. */
3643 if ((e
== NULL
|| !EDGE_CRITICAL_P (e
))
3644 && dominated_by_p (CDI_DOMINATORS
, loc
->bb
, dest_bb
))
3653 /* Update the last node of the list and move to the next one. */
3658 /* If we didn't find an assertion already registered for
3659 NAME COMP_CODE VAL, add a new one at the end of the list of
3660 assertions associated with NAME. */
3661 n
= XNEW (struct assert_locus_d
);
3665 n
->comp_code
= comp_code
;
3673 asserts_for
[SSA_NAME_VERSION (name
)] = n
;
3675 bitmap_set_bit (need_assert_for
, SSA_NAME_VERSION (name
));
3678 /* (COND_OP0 COND_CODE COND_OP1) is a predicate which uses NAME.
3679 Extract a suitable test code and value and store them into *CODE_P and
3680 *VAL_P so the predicate is normalized to NAME *CODE_P *VAL_P.
3682 If no extraction was possible, return FALSE, otherwise return TRUE.
3684 If INVERT is true, then we invert the result stored into *CODE_P. */
3687 extract_code_and_val_from_cond_with_ops (tree name
, enum tree_code cond_code
,
3688 tree cond_op0
, tree cond_op1
,
3689 bool invert
, enum tree_code
*code_p
,
3692 enum tree_code comp_code
;
3695 /* Otherwise, we have a comparison of the form NAME COMP VAL
3696 or VAL COMP NAME. */
3697 if (name
== cond_op1
)
3699 /* If the predicate is of the form VAL COMP NAME, flip
3700 COMP around because we need to register NAME as the
3701 first operand in the predicate. */
3702 comp_code
= swap_tree_comparison (cond_code
);
3707 /* The comparison is of the form NAME COMP VAL, so the
3708 comparison code remains unchanged. */
3709 comp_code
= cond_code
;
3713 /* Invert the comparison code as necessary. */
3715 comp_code
= invert_tree_comparison (comp_code
, 0);
3717 /* VRP does not handle float types. */
3718 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val
)))
3721 /* Do not register always-false predicates.
3722 FIXME: this works around a limitation in fold() when dealing with
3723 enumerations. Given 'enum { N1, N2 } x;', fold will not
3724 fold 'if (x > N2)' to 'if (0)'. */
3725 if ((comp_code
== GT_EXPR
|| comp_code
== LT_EXPR
)
3726 && INTEGRAL_TYPE_P (TREE_TYPE (val
)))
3728 tree min
= TYPE_MIN_VALUE (TREE_TYPE (val
));
3729 tree max
= TYPE_MAX_VALUE (TREE_TYPE (val
));
3731 if (comp_code
== GT_EXPR
3733 || compare_values (val
, max
) == 0))
3736 if (comp_code
== LT_EXPR
3738 || compare_values (val
, min
) == 0))
3741 *code_p
= comp_code
;
3746 /* Try to register an edge assertion for SSA name NAME on edge E for
3747 the condition COND contributing to the conditional jump pointed to by BSI.
3748 Invert the condition COND if INVERT is true.
3749 Return true if an assertion for NAME could be registered. */
3752 register_edge_assert_for_2 (tree name
, edge e
, block_stmt_iterator bsi
,
3753 enum tree_code cond_code
,
3754 tree cond_op0
, tree cond_op1
, bool invert
)
3757 enum tree_code comp_code
;
3758 bool retval
= false;
3760 if (!extract_code_and_val_from_cond_with_ops (name
, cond_code
,
3763 invert
, &comp_code
, &val
))
3766 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
3767 reachable from E. */
3768 if (TEST_BIT (found_in_subgraph
, SSA_NAME_VERSION (name
))
3769 && !has_single_use (name
))
3771 register_new_assert_for (name
, name
, comp_code
, val
, NULL
, e
, bsi
);
3775 /* In the case of NAME <= CST and NAME being defined as
3776 NAME = (unsigned) NAME2 + CST2 we can assert NAME2 >= -CST2
3777 and NAME2 <= CST - CST2. We can do the same for NAME > CST.
3778 This catches range and anti-range tests. */
3779 if ((comp_code
== LE_EXPR
3780 || comp_code
== GT_EXPR
)
3781 && TREE_CODE (val
) == INTEGER_CST
3782 && TYPE_UNSIGNED (TREE_TYPE (val
)))
3784 tree def_stmt
= SSA_NAME_DEF_STMT (name
);
3785 tree cst2
= NULL_TREE
, name2
= NULL_TREE
, name3
= NULL_TREE
;
3787 /* Extract CST2 from the (optional) addition. */
3788 if (TREE_CODE (def_stmt
) == GIMPLE_MODIFY_STMT
3789 && TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == PLUS_EXPR
)
3791 name2
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 0);
3792 cst2
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 1);
3793 if (TREE_CODE (name2
) == SSA_NAME
3794 && TREE_CODE (cst2
) == INTEGER_CST
)
3795 def_stmt
= SSA_NAME_DEF_STMT (name2
);
3798 /* Extract NAME2 from the (optional) sign-changing cast. */
3799 if (TREE_CODE (def_stmt
) == GIMPLE_MODIFY_STMT
3800 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == NOP_EXPR
3801 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == CONVERT_EXPR
))
3803 tree rhs
= GIMPLE_STMT_OPERAND (def_stmt
, 1);
3804 if ((TREE_CODE (rhs
) == NOP_EXPR
3805 || TREE_CODE (rhs
) == CONVERT_EXPR
)
3806 && ! TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (rhs
, 0)))
3807 && (TYPE_PRECISION (TREE_TYPE (rhs
))
3808 == TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (rhs
, 0)))))
3809 name3
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 0);
3812 /* If name3 is used later, create an ASSERT_EXPR for it. */
3813 if (name3
!= NULL_TREE
3814 && TREE_CODE (name3
) == SSA_NAME
3815 && (cst2
== NULL_TREE
3816 || TREE_CODE (cst2
) == INTEGER_CST
)
3817 && INTEGRAL_TYPE_P (TREE_TYPE (name3
))
3818 && TEST_BIT (found_in_subgraph
, SSA_NAME_VERSION (name3
))
3819 && !has_single_use (name3
))
3823 /* Build an expression for the range test. */
3824 tmp
= build1 (NOP_EXPR
, TREE_TYPE (name
), name3
);
3825 if (cst2
!= NULL_TREE
)
3826 tmp
= build2 (PLUS_EXPR
, TREE_TYPE (name
), tmp
, cst2
);
3830 fprintf (dump_file
, "Adding assert for ");
3831 print_generic_expr (dump_file
, name3
, 0);
3832 fprintf (dump_file
, " from ");
3833 print_generic_expr (dump_file
, tmp
, 0);
3834 fprintf (dump_file
, "\n");
3837 register_new_assert_for (name3
, tmp
, comp_code
, val
, NULL
, e
, bsi
);
3842 /* If name2 is used later, create an ASSERT_EXPR for it. */
3843 if (name2
!= NULL_TREE
3844 && TREE_CODE (name2
) == SSA_NAME
3845 && TREE_CODE (cst2
) == INTEGER_CST
3846 && INTEGRAL_TYPE_P (TREE_TYPE (name2
))
3847 && TEST_BIT (found_in_subgraph
, SSA_NAME_VERSION (name2
))
3848 && !has_single_use (name2
))
3852 /* Build an expression for the range test. */
3854 if (TREE_TYPE (name
) != TREE_TYPE (name2
))
3855 tmp
= build1 (NOP_EXPR
, TREE_TYPE (name
), tmp
);
3856 if (cst2
!= NULL_TREE
)
3857 tmp
= build2 (PLUS_EXPR
, TREE_TYPE (name
), tmp
, cst2
);
3861 fprintf (dump_file
, "Adding assert for ");
3862 print_generic_expr (dump_file
, name2
, 0);
3863 fprintf (dump_file
, " from ");
3864 print_generic_expr (dump_file
, tmp
, 0);
3865 fprintf (dump_file
, "\n");
3868 register_new_assert_for (name2
, tmp
, comp_code
, val
, NULL
, e
, bsi
);
3877 /* OP is an operand of a truth value expression which is known to have
3878 a particular value. Register any asserts for OP and for any
3879 operands in OP's defining statement.
3881 If CODE is EQ_EXPR, then we want to register OP is zero (false),
3882 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
3885 register_edge_assert_for_1 (tree op
, enum tree_code code
,
3886 edge e
, block_stmt_iterator bsi
)
3888 bool retval
= false;
3889 tree op_def
, rhs
, val
;
3890 enum tree_code rhs_code
;
3892 /* We only care about SSA_NAMEs. */
3893 if (TREE_CODE (op
) != SSA_NAME
)
3896 /* We know that OP will have a zero or nonzero value. If OP is used
3897 more than once go ahead and register an assert for OP.
3899 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
3900 it will always be set for OP (because OP is used in a COND_EXPR in
3902 if (!has_single_use (op
))
3904 val
= build_int_cst (TREE_TYPE (op
), 0);
3905 register_new_assert_for (op
, op
, code
, val
, NULL
, e
, bsi
);
3909 /* Now look at how OP is set. If it's set from a comparison,
3910 a truth operation or some bit operations, then we may be able
3911 to register information about the operands of that assignment. */
3912 op_def
= SSA_NAME_DEF_STMT (op
);
3913 if (TREE_CODE (op_def
) != GIMPLE_MODIFY_STMT
)
3916 rhs
= GIMPLE_STMT_OPERAND (op_def
, 1);
3917 rhs_code
= TREE_CODE (rhs
);
3919 if (COMPARISON_CLASS_P (rhs
))
3921 bool invert
= (code
== EQ_EXPR
? true : false);
3922 tree op0
= TREE_OPERAND (rhs
, 0);
3923 tree op1
= TREE_OPERAND (rhs
, 1);
3925 if (TREE_CODE (op0
) == SSA_NAME
)
3926 retval
|= register_edge_assert_for_2 (op0
, e
, bsi
, rhs_code
, op0
, op1
,
3928 if (TREE_CODE (op1
) == SSA_NAME
)
3929 retval
|= register_edge_assert_for_2 (op1
, e
, bsi
, rhs_code
, op0
, op1
,
3932 else if ((code
== NE_EXPR
3933 && (TREE_CODE (rhs
) == TRUTH_AND_EXPR
3934 || TREE_CODE (rhs
) == BIT_AND_EXPR
))
3936 && (TREE_CODE (rhs
) == TRUTH_OR_EXPR
3937 || TREE_CODE (rhs
) == BIT_IOR_EXPR
)))
3939 /* Recurse on each operand. */
3940 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 0),
3942 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 1),
3945 else if (TREE_CODE (rhs
) == TRUTH_NOT_EXPR
)
3947 /* Recurse, flipping CODE. */
3948 code
= invert_tree_comparison (code
, false);
3949 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 0),
3952 else if (TREE_CODE (rhs
) == SSA_NAME
)
3954 /* Recurse through the copy. */
3955 retval
|= register_edge_assert_for_1 (rhs
, code
, e
, bsi
);
3957 else if (TREE_CODE (rhs
) == NOP_EXPR
3958 || TREE_CODE (rhs
) == CONVERT_EXPR
)
3960 /* Recurse through the type conversion. */
3961 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 0),
3968 /* Try to register an edge assertion for SSA name NAME on edge E for
3969 the condition COND contributing to the conditional jump pointed to by SI.
3970 Return true if an assertion for NAME could be registered. */
3973 register_edge_assert_for (tree name
, edge e
, block_stmt_iterator si
,
3974 enum tree_code cond_code
, tree cond_op0
,
3978 enum tree_code comp_code
;
3979 bool retval
= false;
3980 bool is_else_edge
= (e
->flags
& EDGE_FALSE_VALUE
) != 0;
3982 /* Do not attempt to infer anything in names that flow through
3984 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name
))
3987 if (!extract_code_and_val_from_cond_with_ops (name
, cond_code
,
3993 /* Register ASSERT_EXPRs for name. */
3994 retval
|= register_edge_assert_for_2 (name
, e
, si
, cond_code
, cond_op0
,
3995 cond_op1
, is_else_edge
);
3998 /* If COND is effectively an equality test of an SSA_NAME against
3999 the value zero or one, then we may be able to assert values
4000 for SSA_NAMEs which flow into COND. */
4002 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
4003 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
4004 have nonzero value. */
4005 if (((comp_code
== EQ_EXPR
&& integer_onep (val
))
4006 || (comp_code
== NE_EXPR
&& integer_zerop (val
))))
4008 tree def_stmt
= SSA_NAME_DEF_STMT (name
);
4010 if (TREE_CODE (def_stmt
) == GIMPLE_MODIFY_STMT
4011 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == TRUTH_AND_EXPR
4012 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == BIT_AND_EXPR
))
4014 tree op0
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 0);
4015 tree op1
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 1);
4016 retval
|= register_edge_assert_for_1 (op0
, NE_EXPR
, e
, si
);
4017 retval
|= register_edge_assert_for_1 (op1
, NE_EXPR
, e
, si
);
4021 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
4022 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
4024 if (((comp_code
== EQ_EXPR
&& integer_zerop (val
))
4025 || (comp_code
== NE_EXPR
&& integer_onep (val
))))
4027 tree def_stmt
= SSA_NAME_DEF_STMT (name
);
4029 if (TREE_CODE (def_stmt
) == GIMPLE_MODIFY_STMT
4030 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == TRUTH_OR_EXPR
4031 /* For BIT_IOR_EXPR only if NAME == 0 both operands have
4032 necessarily zero value. */
4033 || (comp_code
== EQ_EXPR
4034 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1))
4037 tree op0
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 0);
4038 tree op1
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 1);
4039 retval
|= register_edge_assert_for_1 (op0
, EQ_EXPR
, e
, si
);
4040 retval
|= register_edge_assert_for_1 (op1
, EQ_EXPR
, e
, si
);
4048 static bool find_assert_locations (basic_block bb
);
4050 /* Determine whether the outgoing edges of BB should receive an
4051 ASSERT_EXPR for each of the operands of BB's LAST statement.
4052 The last statement of BB must be a COND_EXPR.
4054 If any of the sub-graphs rooted at BB have an interesting use of
4055 the predicate operands, an assert location node is added to the
4056 list of assertions for the corresponding operands. */
4059 find_conditional_asserts (basic_block bb
, tree last
)
4062 block_stmt_iterator bsi
;
4068 need_assert
= false;
4069 bsi
= bsi_for_stmt (last
);
4071 /* Look for uses of the operands in each of the sub-graphs
4072 rooted at BB. We need to check each of the outgoing edges
4073 separately, so that we know what kind of ASSERT_EXPR to
4075 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
4080 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
4081 Otherwise, when we finish traversing each of the sub-graphs, we
4082 won't know whether the variables were found in the sub-graphs or
4083 if they had been found in a block upstream from BB.
4085 This is actually a bad idea is some cases, particularly jump
4086 threading. Consider a CFG like the following:
4096 Assume that one or more operands in the conditional at the
4097 end of block 0 are used in a conditional in block 2, but not
4098 anywhere in block 1. In this case we will not insert any
4099 assert statements in block 1, which may cause us to miss
4100 opportunities to optimize, particularly for jump threading. */
4101 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
4102 RESET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
4104 /* Traverse the strictly dominated sub-graph rooted at E->DEST
4105 to determine if any of the operands in the conditional
4106 predicate are used. */
4107 need_assert
|= find_assert_locations (e
->dest
);
4109 /* Register the necessary assertions for each operand in the
4110 conditional predicate. */
4111 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
4113 tree cond
= COND_EXPR_COND (last
);
4115 need_assert
|= register_edge_assert_for (op
, e
, bsi
,
4117 TREE_OPERAND (cond
, 0),
4118 TREE_OPERAND (cond
, 1));
4120 need_assert
|= register_edge_assert_for (op
, e
, bsi
, EQ_EXPR
, op
,
4125 /* Finally, indicate that we have found the operands in the
4127 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
4128 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
4133 /* Compare two case labels sorting first by the destination label uid
4134 and then by the case value. */
4137 compare_case_labels (const void *p1
, const void *p2
)
4139 const_tree
const case1
= *(const_tree
const*)p1
;
4140 const_tree
const case2
= *(const_tree
const*)p2
;
4141 unsigned int uid1
= DECL_UID (CASE_LABEL (case1
));
4142 unsigned int uid2
= DECL_UID (CASE_LABEL (case2
));
4146 else if (uid1
== uid2
)
4148 /* Make sure the default label is first in a group. */
4149 if (!CASE_LOW (case1
))
4151 else if (!CASE_LOW (case2
))
4154 return tree_int_cst_compare (CASE_LOW (case1
), CASE_LOW (case2
));
4160 /* Determine whether the outgoing edges of BB should receive an
4161 ASSERT_EXPR for each of the operands of BB's LAST statement.
4162 The last statement of BB must be a SWITCH_EXPR.
4164 If any of the sub-graphs rooted at BB have an interesting use of
4165 the predicate operands, an assert location node is added to the
4166 list of assertions for the corresponding operands. */
4169 find_switch_asserts (basic_block bb
, tree last
)
4172 block_stmt_iterator bsi
;
4175 tree vec
= SWITCH_LABELS (last
), vec2
;
4176 size_t n
= TREE_VEC_LENGTH (vec
);
4179 need_assert
= false;
4180 bsi
= bsi_for_stmt (last
);
4181 op
= TREE_OPERAND (last
, 0);
4182 if (TREE_CODE (op
) != SSA_NAME
)
4185 /* Build a vector of case labels sorted by destination label. */
4186 vec2
= make_tree_vec (n
);
4187 for (idx
= 0; idx
< n
; ++idx
)
4188 TREE_VEC_ELT (vec2
, idx
) = TREE_VEC_ELT (vec
, idx
);
4189 qsort (&TREE_VEC_ELT (vec2
, 0), n
, sizeof (tree
), compare_case_labels
);
4191 for (idx
= 0; idx
< n
; ++idx
)
4194 tree cl
= TREE_VEC_ELT (vec2
, idx
);
4196 min
= CASE_LOW (cl
);
4197 max
= CASE_HIGH (cl
);
4199 /* If there are multiple case labels with the same destination
4200 we need to combine them to a single value range for the edge. */
4202 && CASE_LABEL (cl
) == CASE_LABEL (TREE_VEC_ELT (vec2
, idx
+ 1)))
4204 /* Skip labels until the last of the group. */
4208 && CASE_LABEL (cl
) == CASE_LABEL (TREE_VEC_ELT (vec2
, idx
)));
4211 /* Pick up the maximum of the case label range. */
4212 if (CASE_HIGH (TREE_VEC_ELT (vec2
, idx
)))
4213 max
= CASE_HIGH (TREE_VEC_ELT (vec2
, idx
));
4215 max
= CASE_LOW (TREE_VEC_ELT (vec2
, idx
));
4218 /* Nothing to do if the range includes the default label until we
4219 can register anti-ranges. */
4220 if (min
== NULL_TREE
)
4223 /* Find the edge to register the assert expr on. */
4224 e
= find_edge (bb
, label_to_block (CASE_LABEL (cl
)));
4226 /* Remove the SWITCH_EXPR operand from the FOUND_IN_SUBGRAPH bitmap.
4227 Otherwise, when we finish traversing each of the sub-graphs, we
4228 won't know whether the variables were found in the sub-graphs or
4229 if they had been found in a block upstream from BB. */
4230 RESET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
4232 /* Traverse the strictly dominated sub-graph rooted at E->DEST
4233 to determine if any of the operands in the conditional
4234 predicate are used. */
4236 need_assert
|= find_assert_locations (e
->dest
);
4238 /* Register the necessary assertions for the operand in the
4240 need_assert
|= register_edge_assert_for (op
, e
, bsi
,
4241 max
? GE_EXPR
: EQ_EXPR
,
4243 fold_convert (TREE_TYPE (op
),
4247 need_assert
|= register_edge_assert_for (op
, e
, bsi
, LE_EXPR
,
4249 fold_convert (TREE_TYPE (op
),
4254 /* Finally, indicate that we have found the operand in the
4256 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
4262 /* Traverse all the statements in block BB looking for statements that
4263 may generate useful assertions for the SSA names in their operand.
4264 If a statement produces a useful assertion A for name N_i, then the
4265 list of assertions already generated for N_i is scanned to
4266 determine if A is actually needed.
4268 If N_i already had the assertion A at a location dominating the
4269 current location, then nothing needs to be done. Otherwise, the
4270 new location for A is recorded instead.
4272 1- For every statement S in BB, all the variables used by S are
4273 added to bitmap FOUND_IN_SUBGRAPH.
4275 2- If statement S uses an operand N in a way that exposes a known
4276 value range for N, then if N was not already generated by an
4277 ASSERT_EXPR, create a new assert location for N. For instance,
4278 if N is a pointer and the statement dereferences it, we can
4279 assume that N is not NULL.
4281 3- COND_EXPRs are a special case of #2. We can derive range
4282 information from the predicate but need to insert different
4283 ASSERT_EXPRs for each of the sub-graphs rooted at the
4284 conditional block. If the last statement of BB is a conditional
4285 expression of the form 'X op Y', then
4287 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
4289 b) If the conditional is the only entry point to the sub-graph
4290 corresponding to the THEN_CLAUSE, recurse into it. On
4291 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
4292 an ASSERT_EXPR is added for the corresponding variable.
4294 c) Repeat step (b) on the ELSE_CLAUSE.
4296 d) Mark X and Y in FOUND_IN_SUBGRAPH.
4305 In this case, an assertion on the THEN clause is useful to
4306 determine that 'a' is always 9 on that edge. However, an assertion
4307 on the ELSE clause would be unnecessary.
4309 4- If BB does not end in a conditional expression, then we recurse
4310 into BB's dominator children.
4312 At the end of the recursive traversal, every SSA name will have a
4313 list of locations where ASSERT_EXPRs should be added. When a new
4314 location for name N is found, it is registered by calling
4315 register_new_assert_for. That function keeps track of all the
4316 registered assertions to prevent adding unnecessary assertions.
4317 For instance, if a pointer P_4 is dereferenced more than once in a
4318 dominator tree, only the location dominating all the dereference of
4319 P_4 will receive an ASSERT_EXPR.
4321 If this function returns true, then it means that there are names
4322 for which we need to generate ASSERT_EXPRs. Those assertions are
4323 inserted by process_assert_insertions. */
4326 find_assert_locations (basic_block bb
)
4328 block_stmt_iterator si
;
4333 if (TEST_BIT (blocks_visited
, bb
->index
))
4336 SET_BIT (blocks_visited
, bb
->index
);
4338 need_assert
= false;
4340 /* Traverse all PHI nodes in BB marking used operands. */
4341 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
4343 use_operand_p arg_p
;
4346 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_USE
)
4348 tree arg
= USE_FROM_PTR (arg_p
);
4349 if (TREE_CODE (arg
) == SSA_NAME
)
4351 gcc_assert (is_gimple_reg (PHI_RESULT (phi
)));
4352 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (arg
));
4357 /* Traverse all the statements in BB marking used names and looking
4358 for statements that may infer assertions for their used operands. */
4360 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
4365 stmt
= bsi_stmt (si
);
4367 /* See if we can derive an assertion for any of STMT's operands. */
4368 FOR_EACH_SSA_TREE_OPERAND (op
, stmt
, i
, SSA_OP_USE
)
4371 enum tree_code comp_code
;
4373 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
4374 the sub-graph of a conditional block, when we return from
4375 this recursive walk, our parent will use the
4376 FOUND_IN_SUBGRAPH bitset to determine if one of the
4377 operands it was looking for was present in the sub-graph. */
4378 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
4380 /* If OP is used in such a way that we can infer a value
4381 range for it, and we don't find a previous assertion for
4382 it, create a new assertion location node for OP. */
4383 if (infer_value_range (stmt
, op
, &comp_code
, &value
))
4385 /* If we are able to infer a nonzero value range for OP,
4386 then walk backwards through the use-def chain to see if OP
4387 was set via a typecast.
4389 If so, then we can also infer a nonzero value range
4390 for the operand of the NOP_EXPR. */
4391 if (comp_code
== NE_EXPR
&& integer_zerop (value
))
4394 tree def_stmt
= SSA_NAME_DEF_STMT (t
);
4396 while (TREE_CODE (def_stmt
) == GIMPLE_MODIFY_STMT
4398 (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == NOP_EXPR
4400 (TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1),
4403 (TREE_TYPE (TREE_OPERAND
4404 (GIMPLE_STMT_OPERAND (def_stmt
,
4407 t
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 0);
4408 def_stmt
= SSA_NAME_DEF_STMT (t
);
4410 /* Note we want to register the assert for the
4411 operand of the NOP_EXPR after SI, not after the
4413 if (! has_single_use (t
))
4415 register_new_assert_for (t
, t
, comp_code
, value
,
4422 /* If OP is used only once, namely in this STMT, don't
4423 bother creating an ASSERT_EXPR for it. Such an
4424 ASSERT_EXPR would do nothing but increase compile time. */
4425 if (!has_single_use (op
))
4427 register_new_assert_for (op
, op
, comp_code
, value
,
4434 /* Remember the last statement of the block. */
4438 /* If BB's last statement is a conditional expression
4439 involving integer operands, recurse into each of the sub-graphs
4440 rooted at BB to determine if we need to add ASSERT_EXPRs. */
4442 && TREE_CODE (last
) == COND_EXPR
4443 && !fp_predicate (COND_EXPR_COND (last
))
4444 && !ZERO_SSA_OPERANDS (last
, SSA_OP_USE
))
4445 need_assert
|= find_conditional_asserts (bb
, last
);
4448 && TREE_CODE (last
) == SWITCH_EXPR
4449 && !ZERO_SSA_OPERANDS (last
, SSA_OP_USE
))
4450 need_assert
|= find_switch_asserts (bb
, last
);
4452 /* Recurse into the dominator children of BB. */
4453 for (son
= first_dom_son (CDI_DOMINATORS
, bb
);
4455 son
= next_dom_son (CDI_DOMINATORS
, son
))
4456 need_assert
|= find_assert_locations (son
);
4462 /* Create an ASSERT_EXPR for NAME and insert it in the location
4463 indicated by LOC. Return true if we made any edge insertions. */
4466 process_assert_insertions_for (tree name
, assert_locus_t loc
)
4468 /* Build the comparison expression NAME_i COMP_CODE VAL. */
4469 tree stmt
, cond
, assert_expr
;
4473 cond
= build2 (loc
->comp_code
, boolean_type_node
, loc
->expr
, loc
->val
);
4474 assert_expr
= build_assert_expr_for (cond
, name
);
4478 /* We have been asked to insert the assertion on an edge. This
4479 is used only by COND_EXPR and SWITCH_EXPR assertions. */
4480 #if defined ENABLE_CHECKING
4481 gcc_assert (TREE_CODE (bsi_stmt (loc
->si
)) == COND_EXPR
4482 || TREE_CODE (bsi_stmt (loc
->si
)) == SWITCH_EXPR
);
4485 bsi_insert_on_edge (loc
->e
, assert_expr
);
4489 /* Otherwise, we can insert right after LOC->SI iff the
4490 statement must not be the last statement in the block. */
4491 stmt
= bsi_stmt (loc
->si
);
4492 if (!stmt_ends_bb_p (stmt
))
4494 bsi_insert_after (&loc
->si
, assert_expr
, BSI_SAME_STMT
);
4498 /* If STMT must be the last statement in BB, we can only insert new
4499 assertions on the non-abnormal edge out of BB. Note that since
4500 STMT is not control flow, there may only be one non-abnormal edge
4502 FOR_EACH_EDGE (e
, ei
, loc
->bb
->succs
)
4503 if (!(e
->flags
& EDGE_ABNORMAL
))
4505 bsi_insert_on_edge (e
, assert_expr
);
4513 /* Process all the insertions registered for every name N_i registered
4514 in NEED_ASSERT_FOR. The list of assertions to be inserted are
4515 found in ASSERTS_FOR[i]. */
4518 process_assert_insertions (void)
4522 bool update_edges_p
= false;
4523 int num_asserts
= 0;
4525 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4526 dump_all_asserts (dump_file
);
4528 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
4530 assert_locus_t loc
= asserts_for
[i
];
4535 assert_locus_t next
= loc
->next
;
4536 update_edges_p
|= process_assert_insertions_for (ssa_name (i
), loc
);
4544 bsi_commit_edge_inserts ();
4546 if (dump_file
&& (dump_flags
& TDF_STATS
))
4547 fprintf (dump_file
, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
4552 /* Traverse the flowgraph looking for conditional jumps to insert range
4553 expressions. These range expressions are meant to provide information
4554 to optimizations that need to reason in terms of value ranges. They
4555 will not be expanded into RTL. For instance, given:
4564 this pass will transform the code into:
4570 x = ASSERT_EXPR <x, x < y>
4575 y = ASSERT_EXPR <y, x <= y>
4579 The idea is that once copy and constant propagation have run, other
4580 optimizations will be able to determine what ranges of values can 'x'
4581 take in different paths of the code, simply by checking the reaching
4582 definition of 'x'. */
4585 insert_range_assertions (void)
4591 found_in_subgraph
= sbitmap_alloc (num_ssa_names
);
4592 sbitmap_zero (found_in_subgraph
);
4594 blocks_visited
= sbitmap_alloc (last_basic_block
);
4595 sbitmap_zero (blocks_visited
);
4597 need_assert_for
= BITMAP_ALLOC (NULL
);
4598 asserts_for
= XCNEWVEC (assert_locus_t
, num_ssa_names
);
4600 calculate_dominance_info (CDI_DOMINATORS
);
4602 update_ssa_p
= false;
4603 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
4604 if (find_assert_locations (e
->dest
))
4605 update_ssa_p
= true;
4609 process_assert_insertions ();
4610 update_ssa (TODO_update_ssa_no_phi
);
4613 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4615 fprintf (dump_file
, "\nSSA form after inserting ASSERT_EXPRs\n");
4616 dump_function_to_file (current_function_decl
, dump_file
, dump_flags
);
4619 sbitmap_free (found_in_subgraph
);
4621 BITMAP_FREE (need_assert_for
);
4624 /* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays
4625 and "struct" hacks. If VRP can determine that the
4626 array subscript is a constant, check if it is outside valid
4627 range. If the array subscript is a RANGE, warn if it is
4628 non-overlapping with valid range.
4629 IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */
4632 check_array_ref (tree ref
, location_t
* locus
, bool ignore_off_by_one
)
4634 value_range_t
* vr
= NULL
;
4635 tree low_sub
, up_sub
;
4636 tree low_bound
, up_bound
= array_ref_up_bound (ref
);
4638 low_sub
= up_sub
= TREE_OPERAND (ref
, 1);
4640 if (!up_bound
|| TREE_NO_WARNING (ref
)
4641 || TREE_CODE (up_bound
) != INTEGER_CST
4642 /* Can not check flexible arrays. */
4643 || (TYPE_SIZE (TREE_TYPE (ref
)) == NULL_TREE
4644 && TYPE_DOMAIN (TREE_TYPE (ref
)) != NULL_TREE
4645 && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (ref
))) == NULL_TREE
)
4646 /* Accesses after the end of arrays of size 0 (gcc
4647 extension) and 1 are likely intentional ("struct
4649 || compare_tree_int (up_bound
, 1) <= 0)
4652 low_bound
= array_ref_low_bound (ref
);
4654 if (TREE_CODE (low_sub
) == SSA_NAME
)
4656 vr
= get_value_range (low_sub
);
4657 if (vr
->type
== VR_RANGE
|| vr
->type
== VR_ANTI_RANGE
)
4659 low_sub
= vr
->type
== VR_RANGE
? vr
->max
: vr
->min
;
4660 up_sub
= vr
->type
== VR_RANGE
? vr
->min
: vr
->max
;
4664 if (vr
&& vr
->type
== VR_ANTI_RANGE
)
4666 if (TREE_CODE (up_sub
) == INTEGER_CST
4667 && tree_int_cst_lt (up_bound
, up_sub
)
4668 && TREE_CODE (low_sub
) == INTEGER_CST
4669 && tree_int_cst_lt (low_sub
, low_bound
))
4671 warning (OPT_Warray_bounds
,
4672 "%Harray subscript is outside array bounds", locus
);
4673 TREE_NO_WARNING (ref
) = 1;
4676 else if (TREE_CODE (up_sub
) == INTEGER_CST
4677 && tree_int_cst_lt (up_bound
, up_sub
)
4678 && !tree_int_cst_equal (up_bound
, up_sub
)
4679 && (!ignore_off_by_one
4680 || !tree_int_cst_equal (int_const_binop (PLUS_EXPR
,
4686 warning (OPT_Warray_bounds
, "%Harray subscript is above array bounds",
4688 TREE_NO_WARNING (ref
) = 1;
4690 else if (TREE_CODE (low_sub
) == INTEGER_CST
4691 && tree_int_cst_lt (low_sub
, low_bound
))
4693 warning (OPT_Warray_bounds
, "%Harray subscript is below array bounds",
4695 TREE_NO_WARNING (ref
) = 1;
4699 /* Searches if the expr T, located at LOCATION computes
4700 address of an ARRAY_REF, and call check_array_ref on it. */
4703 search_for_addr_array(tree t
, location_t
* location
)
4705 while (TREE_CODE (t
) == SSA_NAME
)
4707 t
= SSA_NAME_DEF_STMT (t
);
4708 if (TREE_CODE (t
) != GIMPLE_MODIFY_STMT
)
4710 t
= GIMPLE_STMT_OPERAND (t
, 1);
4714 /* We are only interested in addresses of ARRAY_REF's. */
4715 if (TREE_CODE (t
) != ADDR_EXPR
)
4718 /* Check each ARRAY_REFs in the reference chain. */
4721 if (TREE_CODE (t
) == ARRAY_REF
)
4722 check_array_ref (t
, location
, true /*ignore_off_by_one*/);
4724 t
= TREE_OPERAND(t
,0);
4726 while (handled_component_p (t
));
4729 /* walk_tree() callback that checks if *TP is
4730 an ARRAY_REF inside an ADDR_EXPR (in which an array
4731 subscript one outside the valid range is allowed). Call
4732 check_array_ref for each ARRAY_REF found. The location is
4736 check_array_bounds (tree
*tp
, int *walk_subtree
, void *data
)
4739 tree stmt
= (tree
)data
;
4740 location_t
*location
= EXPR_LOCUS (stmt
);
4742 if (!EXPR_HAS_LOCATION (stmt
))
4744 *walk_subtree
= FALSE
;
4748 *walk_subtree
= TRUE
;
4750 if (TREE_CODE (t
) == ARRAY_REF
)
4751 check_array_ref (t
, location
, false /*ignore_off_by_one*/);
4753 if (TREE_CODE (t
) == INDIRECT_REF
4754 || (TREE_CODE (t
) == RETURN_EXPR
&& TREE_OPERAND (t
, 0)))
4755 search_for_addr_array (TREE_OPERAND (t
, 0), location
);
4756 else if (TREE_CODE (t
) == CALL_EXPR
)
4759 call_expr_arg_iterator iter
;
4761 FOR_EACH_CALL_EXPR_ARG (arg
, iter
, t
)
4762 search_for_addr_array (arg
, location
);
4765 if (TREE_CODE (t
) == ADDR_EXPR
)
4766 *walk_subtree
= FALSE
;
4771 /* Walk over all statements of all reachable BBs and call check_array_bounds
4775 check_all_array_refs (void)
4778 block_stmt_iterator si
;
4782 /* Skip bb's that are clearly unreachable. */
4783 if (single_pred_p (bb
))
4785 basic_block pred_bb
= EDGE_PRED (bb
, 0)->src
;
4786 tree ls
= NULL_TREE
;
4788 if (!bsi_end_p (bsi_last (pred_bb
)))
4789 ls
= bsi_stmt (bsi_last (pred_bb
));
4791 if (ls
&& TREE_CODE (ls
) == COND_EXPR
4792 && ((COND_EXPR_COND (ls
) == boolean_false_node
4793 && (EDGE_PRED (bb
, 0)->flags
& EDGE_TRUE_VALUE
))
4794 || (COND_EXPR_COND (ls
) == boolean_true_node
4795 && (EDGE_PRED (bb
, 0)->flags
& EDGE_FALSE_VALUE
))))
4798 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
4799 walk_tree (bsi_stmt_ptr (si
), check_array_bounds
,
4800 bsi_stmt (si
), NULL
);
4804 /* Convert range assertion expressions into the implied copies and
4805 copy propagate away the copies. Doing the trivial copy propagation
4806 here avoids the need to run the full copy propagation pass after
4809 FIXME, this will eventually lead to copy propagation removing the
4810 names that had useful range information attached to them. For
4811 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
4812 then N_i will have the range [3, +INF].
4814 However, by converting the assertion into the implied copy
4815 operation N_i = N_j, we will then copy-propagate N_j into the uses
4816 of N_i and lose the range information. We may want to hold on to
4817 ASSERT_EXPRs a little while longer as the ranges could be used in
4818 things like jump threading.
4820 The problem with keeping ASSERT_EXPRs around is that passes after
4821 VRP need to handle them appropriately.
4823 Another approach would be to make the range information a first
4824 class property of the SSA_NAME so that it can be queried from
4825 any pass. This is made somewhat more complex by the need for
4826 multiple ranges to be associated with one SSA_NAME. */
4829 remove_range_assertions (void)
4832 block_stmt_iterator si
;
4834 /* Note that the BSI iterator bump happens at the bottom of the
4835 loop and no bump is necessary if we're removing the statement
4836 referenced by the current BSI. */
4838 for (si
= bsi_start (bb
); !bsi_end_p (si
);)
4840 tree stmt
= bsi_stmt (si
);
4843 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
4844 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt
, 1)) == ASSERT_EXPR
)
4846 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1), var
;
4847 tree cond
= fold (ASSERT_EXPR_COND (rhs
));
4848 use_operand_p use_p
;
4849 imm_use_iterator iter
;
4851 gcc_assert (cond
!= boolean_false_node
);
4853 /* Propagate the RHS into every use of the LHS. */
4854 var
= ASSERT_EXPR_VAR (rhs
);
4855 FOR_EACH_IMM_USE_STMT (use_stmt
, iter
,
4856 GIMPLE_STMT_OPERAND (stmt
, 0))
4857 FOR_EACH_IMM_USE_ON_STMT (use_p
, iter
)
4859 SET_USE (use_p
, var
);
4860 gcc_assert (TREE_CODE (var
) == SSA_NAME
);
4863 /* And finally, remove the copy, it is not needed. */
4864 bsi_remove (&si
, true);
4865 release_defs (stmt
);
4871 sbitmap_free (blocks_visited
);
4875 /* Return true if STMT is interesting for VRP. */
4878 stmt_interesting_for_vrp (tree stmt
)
4880 if (TREE_CODE (stmt
) == PHI_NODE
4881 && is_gimple_reg (PHI_RESULT (stmt
))
4882 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))
4883 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))))
4885 else if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
4887 tree lhs
= GIMPLE_STMT_OPERAND (stmt
, 0);
4888 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
4890 /* In general, assignments with virtual operands are not useful
4891 for deriving ranges, with the obvious exception of calls to
4892 builtin functions. */
4893 if (TREE_CODE (lhs
) == SSA_NAME
4894 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
4895 || POINTER_TYPE_P (TREE_TYPE (lhs
)))
4896 && ((TREE_CODE (rhs
) == CALL_EXPR
4897 && TREE_CODE (CALL_EXPR_FN (rhs
)) == ADDR_EXPR
4898 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs
), 0))
4899 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs
), 0)))
4900 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
)))
4903 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
4910 /* Initialize local data structures for VRP. */
4913 vrp_initialize (void)
4917 vr_value
= XCNEWVEC (value_range_t
*, num_ssa_names
);
4918 vr_phi_edge_counts
= XCNEWVEC (int, num_ssa_names
);
4922 block_stmt_iterator si
;
4925 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
4927 if (!stmt_interesting_for_vrp (phi
))
4929 tree lhs
= PHI_RESULT (phi
);
4930 set_value_range_to_varying (get_value_range (lhs
));
4931 DONT_SIMULATE_AGAIN (phi
) = true;
4934 DONT_SIMULATE_AGAIN (phi
) = false;
4937 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
4939 tree stmt
= bsi_stmt (si
);
4941 if (!stmt_interesting_for_vrp (stmt
))
4945 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, i
, SSA_OP_DEF
)
4946 set_value_range_to_varying (get_value_range (def
));
4947 DONT_SIMULATE_AGAIN (stmt
) = true;
4951 DONT_SIMULATE_AGAIN (stmt
) = false;
4958 /* Visit assignment STMT. If it produces an interesting range, record
4959 the SSA name in *OUTPUT_P. */
4961 static enum ssa_prop_result
4962 vrp_visit_assignment (tree stmt
, tree
*output_p
)
4967 lhs
= GIMPLE_STMT_OPERAND (stmt
, 0);
4968 rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
4970 /* We only keep track of ranges in integral and pointer types. */
4971 if (TREE_CODE (lhs
) == SSA_NAME
4972 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
4973 /* It is valid to have NULL MIN/MAX values on a type. See
4974 build_range_type. */
4975 && TYPE_MIN_VALUE (TREE_TYPE (lhs
))
4976 && TYPE_MAX_VALUE (TREE_TYPE (lhs
)))
4977 || POINTER_TYPE_P (TREE_TYPE (lhs
))))
4980 value_range_t new_vr
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
4982 extract_range_from_expr (&new_vr
, rhs
);
4984 /* If STMT is inside a loop, we may be able to know something
4985 else about the range of LHS by examining scalar evolution
4987 if (current_loops
&& (l
= loop_containing_stmt (stmt
)))
4988 adjust_range_with_scev (&new_vr
, l
, stmt
, lhs
);
4990 if (update_value_range (lhs
, &new_vr
))
4994 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4996 fprintf (dump_file
, "Found new range for ");
4997 print_generic_expr (dump_file
, lhs
, 0);
4998 fprintf (dump_file
, ": ");
4999 dump_value_range (dump_file
, &new_vr
);
5000 fprintf (dump_file
, "\n\n");
5003 if (new_vr
.type
== VR_VARYING
)
5004 return SSA_PROP_VARYING
;
5006 return SSA_PROP_INTERESTING
;
5009 return SSA_PROP_NOT_INTERESTING
;
5012 /* Every other statement produces no useful ranges. */
5013 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
5014 set_value_range_to_varying (get_value_range (def
));
5016 return SSA_PROP_VARYING
;
5019 /* Helper that gets the value range of the SSA_NAME with version I
5020 or a symbolic range containing the SSA_NAME only if the value range
5021 is varying or undefined. */
5023 static inline value_range_t
5024 get_vr_for_comparison (int i
)
5026 value_range_t vr
= *(vr_value
[i
]);
5028 /* If name N_i does not have a valid range, use N_i as its own
5029 range. This allows us to compare against names that may
5030 have N_i in their ranges. */
5031 if (vr
.type
== VR_VARYING
|| vr
.type
== VR_UNDEFINED
)
5034 vr
.min
= ssa_name (i
);
5035 vr
.max
= ssa_name (i
);
5041 /* Compare all the value ranges for names equivalent to VAR with VAL
5042 using comparison code COMP. Return the same value returned by
5043 compare_range_with_value, including the setting of
5044 *STRICT_OVERFLOW_P. */
5047 compare_name_with_value (enum tree_code comp
, tree var
, tree val
,
5048 bool *strict_overflow_p
)
5054 int used_strict_overflow
;
5056 value_range_t equiv_vr
;
5058 /* Get the set of equivalences for VAR. */
5059 e
= get_value_range (var
)->equiv
;
5061 /* Start at -1. Set it to 0 if we do a comparison without relying
5062 on overflow, or 1 if all comparisons rely on overflow. */
5063 used_strict_overflow
= -1;
5065 /* Compare vars' value range with val. */
5066 equiv_vr
= get_vr_for_comparison (SSA_NAME_VERSION (var
));
5068 retval
= compare_range_with_value (comp
, &equiv_vr
, val
, &sop
);
5070 used_strict_overflow
= sop
? 1 : 0;
5072 /* If the equiv set is empty we have done all work we need to do. */
5076 && used_strict_overflow
> 0)
5077 *strict_overflow_p
= true;
5081 EXECUTE_IF_SET_IN_BITMAP (e
, 0, i
, bi
)
5083 equiv_vr
= get_vr_for_comparison (i
);
5085 t
= compare_range_with_value (comp
, &equiv_vr
, val
, &sop
);
5088 /* If we get different answers from different members
5089 of the equivalence set this check must be in a dead
5090 code region. Folding it to a trap representation
5091 would be correct here. For now just return don't-know. */
5101 used_strict_overflow
= 0;
5102 else if (used_strict_overflow
< 0)
5103 used_strict_overflow
= 1;
5108 && used_strict_overflow
> 0)
5109 *strict_overflow_p
= true;
5115 /* Given a comparison code COMP and names N1 and N2, compare all the
5116 ranges equivalent to N1 against all the ranges equivalent to N2
5117 to determine the value of N1 COMP N2. Return the same value
5118 returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate
5119 whether we relied on an overflow infinity in the comparison. */
5123 compare_names (enum tree_code comp
, tree n1
, tree n2
,
5124 bool *strict_overflow_p
)
5128 bitmap_iterator bi1
, bi2
;
5130 int used_strict_overflow
;
5131 static bitmap_obstack
*s_obstack
= NULL
;
5132 static bitmap s_e1
= NULL
, s_e2
= NULL
;
5134 /* Compare the ranges of every name equivalent to N1 against the
5135 ranges of every name equivalent to N2. */
5136 e1
= get_value_range (n1
)->equiv
;
5137 e2
= get_value_range (n2
)->equiv
;
5139 /* Use the fake bitmaps if e1 or e2 are not available. */
5140 if (s_obstack
== NULL
)
5142 s_obstack
= XNEW (bitmap_obstack
);
5143 bitmap_obstack_initialize (s_obstack
);
5144 s_e1
= BITMAP_ALLOC (s_obstack
);
5145 s_e2
= BITMAP_ALLOC (s_obstack
);
5152 /* Add N1 and N2 to their own set of equivalences to avoid
5153 duplicating the body of the loop just to check N1 and N2
5155 bitmap_set_bit (e1
, SSA_NAME_VERSION (n1
));
5156 bitmap_set_bit (e2
, SSA_NAME_VERSION (n2
));
5158 /* If the equivalence sets have a common intersection, then the two
5159 names can be compared without checking their ranges. */
5160 if (bitmap_intersect_p (e1
, e2
))
5162 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
5163 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
5165 return (comp
== EQ_EXPR
|| comp
== GE_EXPR
|| comp
== LE_EXPR
)
5167 : boolean_false_node
;
5170 /* Start at -1. Set it to 0 if we do a comparison without relying
5171 on overflow, or 1 if all comparisons rely on overflow. */
5172 used_strict_overflow
= -1;
5174 /* Otherwise, compare all the equivalent ranges. First, add N1 and
5175 N2 to their own set of equivalences to avoid duplicating the body
5176 of the loop just to check N1 and N2 ranges. */
5177 EXECUTE_IF_SET_IN_BITMAP (e1
, 0, i1
, bi1
)
5179 value_range_t vr1
= get_vr_for_comparison (i1
);
5181 t
= retval
= NULL_TREE
;
5182 EXECUTE_IF_SET_IN_BITMAP (e2
, 0, i2
, bi2
)
5186 value_range_t vr2
= get_vr_for_comparison (i2
);
5188 t
= compare_ranges (comp
, &vr1
, &vr2
, &sop
);
5191 /* If we get different answers from different members
5192 of the equivalence set this check must be in a dead
5193 code region. Folding it to a trap representation
5194 would be correct here. For now just return don't-know. */
5198 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
5199 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
5205 used_strict_overflow
= 0;
5206 else if (used_strict_overflow
< 0)
5207 used_strict_overflow
= 1;
5213 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
5214 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
5215 if (used_strict_overflow
> 0)
5216 *strict_overflow_p
= true;
5221 /* None of the equivalent ranges are useful in computing this
5223 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
5224 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
5228 /* Helper function for vrp_evaluate_conditional_warnv. */
5231 vrp_evaluate_conditional_warnv_with_ops (enum tree_code code
, tree op0
,
5232 tree op1
, bool use_equiv_p
,
5233 bool *strict_overflow_p
)
5235 /* We only deal with integral and pointer types. */
5236 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
5237 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
5242 if (TREE_CODE (op0
) == SSA_NAME
&& TREE_CODE (op1
) == SSA_NAME
)
5243 return compare_names (code
, op0
, op1
,
5245 else if (TREE_CODE (op0
) == SSA_NAME
)
5246 return compare_name_with_value (code
, op0
, op1
,
5248 else if (TREE_CODE (op1
) == SSA_NAME
)
5249 return (compare_name_with_value
5250 (swap_tree_comparison (code
), op1
, op0
,
5251 strict_overflow_p
));
5255 value_range_t
*vr0
, *vr1
;
5257 vr0
= (TREE_CODE (op0
) == SSA_NAME
) ? get_value_range (op0
) : NULL
;
5258 vr1
= (TREE_CODE (op1
) == SSA_NAME
) ? get_value_range (op1
) : NULL
;
5261 return compare_ranges (code
, vr0
, vr1
,
5263 else if (vr0
&& vr1
== NULL
)
5264 return compare_range_with_value (code
, vr0
, op1
,
5266 else if (vr0
== NULL
&& vr1
)
5267 return (compare_range_with_value
5268 (swap_tree_comparison (code
), vr1
, op0
,
5269 strict_overflow_p
));
5274 /* Given (CODE OP0 OP1) within STMT, try to simplify it based on value range
5275 information. Return NULL if the conditional can not be evaluated.
5276 The ranges of all the names equivalent with the operands in COND
5277 will be used when trying to compute the value. If the result is
5278 based on undefined signed overflow, issue a warning if
5282 vrp_evaluate_conditional (enum tree_code code
, tree op0
, tree op1
, tree stmt
)
5288 ret
= vrp_evaluate_conditional_warnv_with_ops (code
,
5296 enum warn_strict_overflow_code wc
;
5297 const char* warnmsg
;
5299 if (is_gimple_min_invariant (ret
))
5301 wc
= WARN_STRICT_OVERFLOW_CONDITIONAL
;
5302 warnmsg
= G_("assuming signed overflow does not occur when "
5303 "simplifying conditional to constant");
5307 wc
= WARN_STRICT_OVERFLOW_COMPARISON
;
5308 warnmsg
= G_("assuming signed overflow does not occur when "
5309 "simplifying conditional");
5312 if (issue_strict_overflow_warning (wc
))
5316 if (!EXPR_HAS_LOCATION (stmt
))
5317 locus
= input_location
;
5319 locus
= EXPR_LOCATION (stmt
);
5320 warning (OPT_Wstrict_overflow
, "%H%s", &locus
, warnmsg
);
5324 if (warn_type_limits
5326 && TREE_CODE_CLASS (code
) == tcc_comparison
5327 && TREE_CODE (op0
) == SSA_NAME
)
5329 /* If the comparison is being folded and the operand on the LHS
5330 is being compared against a constant value that is outside of
5331 the natural range of OP0's type, then the predicate will
5332 always fold regardless of the value of OP0. If -Wtype-limits
5333 was specified, emit a warning. */
5334 const char *warnmsg
= NULL
;
5335 tree type
= TREE_TYPE (op0
);
5336 value_range_t
*vr0
= get_value_range (op0
);
5338 if (vr0
->type
!= VR_VARYING
5339 && INTEGRAL_TYPE_P (type
)
5340 && vrp_val_is_min (vr0
->min
)
5341 && vrp_val_is_max (vr0
->max
)
5342 && is_gimple_min_invariant (op1
))
5344 if (integer_zerop (ret
))
5345 warnmsg
= G_("comparison always false due to limited range of "
5348 warnmsg
= G_("comparison always true due to limited range of "
5356 if (!EXPR_HAS_LOCATION (stmt
))
5357 locus
= input_location
;
5359 locus
= EXPR_LOCATION (stmt
);
5361 warning (OPT_Wtype_limits
, "%H%s", &locus
, warnmsg
);
5369 /* Visit conditional statement STMT. If we can determine which edge
5370 will be taken out of STMT's basic block, record it in
5371 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
5372 SSA_PROP_VARYING. */
5374 static enum ssa_prop_result
5375 vrp_visit_cond_stmt (tree stmt
, edge
*taken_edge_p
)
5380 *taken_edge_p
= NULL
;
5381 cond
= COND_EXPR_COND (stmt
);
5383 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5388 fprintf (dump_file
, "\nVisiting conditional with predicate: ");
5389 print_generic_expr (dump_file
, cond
, 0);
5390 fprintf (dump_file
, "\nWith known ranges\n");
5392 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, i
, SSA_OP_USE
)
5394 fprintf (dump_file
, "\t");
5395 print_generic_expr (dump_file
, use
, 0);
5396 fprintf (dump_file
, ": ");
5397 dump_value_range (dump_file
, vr_value
[SSA_NAME_VERSION (use
)]);
5400 fprintf (dump_file
, "\n");
5403 /* Compute the value of the predicate COND by checking the known
5404 ranges of each of its operands.
5406 Note that we cannot evaluate all the equivalent ranges here
5407 because those ranges may not yet be final and with the current
5408 propagation strategy, we cannot determine when the value ranges
5409 of the names in the equivalence set have changed.
5411 For instance, given the following code fragment
5415 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
5419 Assume that on the first visit to i_14, i_5 has the temporary
5420 range [8, 8] because the second argument to the PHI function is
5421 not yet executable. We derive the range ~[0, 0] for i_14 and the
5422 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
5423 the first time, since i_14 is equivalent to the range [8, 8], we
5424 determine that the predicate is always false.
5426 On the next round of propagation, i_13 is determined to be
5427 VARYING, which causes i_5 to drop down to VARYING. So, another
5428 visit to i_14 is scheduled. In this second visit, we compute the
5429 exact same range and equivalence set for i_14, namely ~[0, 0] and
5430 { i_5 }. But we did not have the previous range for i_5
5431 registered, so vrp_visit_assignment thinks that the range for
5432 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
5433 is not visited again, which stops propagation from visiting
5434 statements in the THEN clause of that if().
5436 To properly fix this we would need to keep the previous range
5437 value for the names in the equivalence set. This way we would've
5438 discovered that from one visit to the other i_5 changed from
5439 range [8, 8] to VR_VARYING.
5441 However, fixing this apparent limitation may not be worth the
5442 additional checking. Testing on several code bases (GCC, DLV,
5443 MICO, TRAMP3D and SPEC2000) showed that doing this results in
5444 4 more predicates folded in SPEC. */
5447 if (TREE_CODE (cond
) == SSA_NAME
)
5448 val
= vrp_evaluate_conditional_warnv_with_ops (EQ_EXPR
,
5454 val
= vrp_evaluate_conditional_warnv_with_ops (TREE_CODE (cond
),
5455 TREE_OPERAND (cond
, 0),
5456 TREE_OPERAND (cond
, 1),
5462 *taken_edge_p
= find_taken_edge (bb_for_stmt (stmt
), val
);
5465 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5467 "\nIgnoring predicate evaluation because "
5468 "it assumes that signed overflow is undefined");
5473 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5475 fprintf (dump_file
, "\nPredicate evaluates to: ");
5476 if (val
== NULL_TREE
)
5477 fprintf (dump_file
, "DON'T KNOW\n");
5479 print_generic_stmt (dump_file
, val
, 0);
5482 return (*taken_edge_p
) ? SSA_PROP_INTERESTING
: SSA_PROP_VARYING
;
5485 /* Searches the case label vector VEC for the index *IDX of the CASE_LABEL
5486 that includes the value VAL. The search is restricted to the range
5487 [START_IDX, n - 2] where n is the size of VEC (n - 1 is the default label).
5489 If there is a CASE_LABEL for VAL, its index is placed in IDX and true is
5492 If there is no CASE_LABEL for VAL and the is one that is larger than VAL,
5493 it is placed in IDX and false is returned.
5495 If VAL is larger than any CASE_LABEL, n - 1 is placed on IDX and false is
5499 find_case_label_index (tree vec
, size_t start_idx
, tree val
, size_t *idx
)
5501 size_t n
= TREE_VEC_LENGTH (vec
);
5504 /* Find case label for minimum of the value range or the next one.
5505 At each iteration we are searching in [low, high - 1]. */
5507 for (low
= start_idx
, high
= n
- 1; high
!= low
; )
5511 /* Note that i != high, so we never ask for n - 1. */
5512 size_t i
= (high
+ low
) / 2;
5513 t
= TREE_VEC_ELT (vec
, i
);
5515 /* Cache the result of comparing CASE_LOW and val. */
5516 cmp
= tree_int_cst_compare (CASE_LOW (t
), val
);
5520 /* Ranges cannot be empty. */
5529 if (CASE_HIGH (t
) != NULL
5530 && tree_int_cst_compare (CASE_HIGH (t
), val
) >= 0)
5542 /* Searches the case label vector VEC for the range of CASE_LABELs that is used
5543 for values between MIN and MAX. The first index is placed in MIN_IDX. The
5544 last index is placed in MAX_IDX. If the range of CASE_LABELs is empty
5545 then MAX_IDX < MIN_IDX.
5546 Returns true if the default label is not needed. */
5549 find_case_label_range (tree vec
, tree min
, tree max
, size_t *min_idx
, size_t *max_idx
)
5552 bool min_take_default
= !find_case_label_index (vec
, 0, min
, &i
);
5553 bool max_take_default
= !find_case_label_index (vec
, i
, max
, &j
);
5557 && max_take_default
)
5559 /* Only the default case label reached.
5560 Return an empty range. */
5567 bool take_default
= min_take_default
|| max_take_default
;
5571 if (max_take_default
)
5574 /* If the case label range is continuous, we do not need
5575 the default case label. Verify that. */
5576 high
= CASE_LOW (TREE_VEC_ELT (vec
, i
));
5577 if (CASE_HIGH (TREE_VEC_ELT (vec
, i
)))
5578 high
= CASE_HIGH (TREE_VEC_ELT (vec
, i
));
5579 for (k
= i
+ 1; k
<= j
; ++k
)
5581 low
= CASE_LOW (TREE_VEC_ELT (vec
, k
));
5582 if (!integer_onep (int_const_binop (MINUS_EXPR
, low
, high
, 0)))
5584 take_default
= true;
5588 if (CASE_HIGH (TREE_VEC_ELT (vec
, k
)))
5589 high
= CASE_HIGH (TREE_VEC_ELT (vec
, k
));
5594 return !take_default
;
5598 /* Visit switch statement STMT. If we can determine which edge
5599 will be taken out of STMT's basic block, record it in
5600 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
5601 SSA_PROP_VARYING. */
5603 static enum ssa_prop_result
5604 vrp_visit_switch_stmt (tree stmt
, edge
*taken_edge_p
)
5608 size_t i
= 0, j
= 0, n
;
5612 *taken_edge_p
= NULL
;
5613 op
= TREE_OPERAND (stmt
, 0);
5614 if (TREE_CODE (op
) != SSA_NAME
)
5615 return SSA_PROP_VARYING
;
5617 vr
= get_value_range (op
);
5618 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5620 fprintf (dump_file
, "\nVisiting switch expression with operand ");
5621 print_generic_expr (dump_file
, op
, 0);
5622 fprintf (dump_file
, " with known range ");
5623 dump_value_range (dump_file
, vr
);
5624 fprintf (dump_file
, "\n");
5627 if (vr
->type
!= VR_RANGE
5628 || symbolic_range_p (vr
))
5629 return SSA_PROP_VARYING
;
5631 /* Find the single edge that is taken from the switch expression. */
5632 vec
= SWITCH_LABELS (stmt
);
5633 n
= TREE_VEC_LENGTH (vec
);
5635 take_default
= !find_case_label_range (vec
, vr
->min
, vr
->max
, &i
, &j
);
5637 /* Check if the range spans no CASE_LABEL. If so, we only reach the default
5641 gcc_assert (take_default
);
5642 val
= TREE_VEC_ELT (vec
, n
- 1);
5646 /* Check if labels with index i to j and maybe the default label
5647 are all reaching the same label. */
5649 val
= TREE_VEC_ELT (vec
, i
);
5651 && CASE_LABEL (TREE_VEC_ELT (vec
, n
- 1)) != CASE_LABEL (val
))
5653 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5654 fprintf (dump_file
, " not a single destination for this "
5656 return SSA_PROP_VARYING
;
5658 for (++i
; i
<= j
; ++i
)
5660 if (CASE_LABEL (TREE_VEC_ELT (vec
, i
)) != CASE_LABEL (val
))
5662 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5663 fprintf (dump_file
, " not a single destination for this "
5665 return SSA_PROP_VARYING
;
5670 *taken_edge_p
= find_edge (bb_for_stmt (stmt
),
5671 label_to_block (CASE_LABEL (val
)));
5673 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5675 fprintf (dump_file
, " will take edge to ");
5676 print_generic_stmt (dump_file
, CASE_LABEL (val
), 0);
5679 return SSA_PROP_INTERESTING
;
5683 /* Evaluate statement STMT. If the statement produces a useful range,
5684 return SSA_PROP_INTERESTING and record the SSA name with the
5685 interesting range into *OUTPUT_P.
5687 If STMT is a conditional branch and we can determine its truth
5688 value, the taken edge is recorded in *TAKEN_EDGE_P.
5690 If STMT produces a varying value, return SSA_PROP_VARYING. */
5692 static enum ssa_prop_result
5693 vrp_visit_stmt (tree stmt
, edge
*taken_edge_p
, tree
*output_p
)
5699 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5701 fprintf (dump_file
, "\nVisiting statement:\n");
5702 print_generic_stmt (dump_file
, stmt
, dump_flags
);
5703 fprintf (dump_file
, "\n");
5706 ann
= stmt_ann (stmt
);
5707 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
5709 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
5711 /* In general, assignments with virtual operands are not useful
5712 for deriving ranges, with the obvious exception of calls to
5713 builtin functions. */
5714 if ((TREE_CODE (rhs
) == CALL_EXPR
5715 && TREE_CODE (CALL_EXPR_FN (rhs
)) == ADDR_EXPR
5716 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs
), 0))
5717 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs
), 0)))
5718 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
5719 return vrp_visit_assignment (stmt
, output_p
);
5721 else if (TREE_CODE (stmt
) == COND_EXPR
)
5722 return vrp_visit_cond_stmt (stmt
, taken_edge_p
);
5723 else if (TREE_CODE (stmt
) == SWITCH_EXPR
)
5724 return vrp_visit_switch_stmt (stmt
, taken_edge_p
);
5726 /* All other statements produce nothing of interest for VRP, so mark
5727 their outputs varying and prevent further simulation. */
5728 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
5729 set_value_range_to_varying (get_value_range (def
));
5731 return SSA_PROP_VARYING
;
5735 /* Meet operation for value ranges. Given two value ranges VR0 and
5736 VR1, store in VR0 a range that contains both VR0 and VR1. This
5737 may not be the smallest possible such range. */
5740 vrp_meet (value_range_t
*vr0
, value_range_t
*vr1
)
5742 if (vr0
->type
== VR_UNDEFINED
)
5744 copy_value_range (vr0
, vr1
);
5748 if (vr1
->type
== VR_UNDEFINED
)
5750 /* Nothing to do. VR0 already has the resulting range. */
5754 if (vr0
->type
== VR_VARYING
)
5756 /* Nothing to do. VR0 already has the resulting range. */
5760 if (vr1
->type
== VR_VARYING
)
5762 set_value_range_to_varying (vr0
);
5766 if (vr0
->type
== VR_RANGE
&& vr1
->type
== VR_RANGE
)
5771 /* Compute the convex hull of the ranges. The lower limit of
5772 the new range is the minimum of the two ranges. If they
5773 cannot be compared, then give up. */
5774 cmp
= compare_values (vr0
->min
, vr1
->min
);
5775 if (cmp
== 0 || cmp
== 1)
5782 /* Similarly, the upper limit of the new range is the maximum
5783 of the two ranges. If they cannot be compared, then
5785 cmp
= compare_values (vr0
->max
, vr1
->max
);
5786 if (cmp
== 0 || cmp
== -1)
5793 /* Check for useless ranges. */
5794 if (INTEGRAL_TYPE_P (TREE_TYPE (min
))
5795 && ((vrp_val_is_min (min
) || is_overflow_infinity (min
))
5796 && (vrp_val_is_max (max
) || is_overflow_infinity (max
))))
5799 /* The resulting set of equivalences is the intersection of
5801 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
5802 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
5803 else if (vr0
->equiv
&& !vr1
->equiv
)
5804 bitmap_clear (vr0
->equiv
);
5806 set_value_range (vr0
, vr0
->type
, min
, max
, vr0
->equiv
);
5808 else if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
5810 /* Two anti-ranges meet only if their complements intersect.
5811 Only handle the case of identical ranges. */
5812 if (compare_values (vr0
->min
, vr1
->min
) == 0
5813 && compare_values (vr0
->max
, vr1
->max
) == 0
5814 && compare_values (vr0
->min
, vr0
->max
) == 0)
5816 /* The resulting set of equivalences is the intersection of
5818 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
5819 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
5820 else if (vr0
->equiv
&& !vr1
->equiv
)
5821 bitmap_clear (vr0
->equiv
);
5826 else if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
5828 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
5829 only handle the case where the ranges have an empty intersection.
5830 The result of the meet operation is the anti-range. */
5831 if (!symbolic_range_p (vr0
)
5832 && !symbolic_range_p (vr1
)
5833 && !value_ranges_intersect_p (vr0
, vr1
))
5835 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
5836 set. We need to compute the intersection of the two
5837 equivalence sets. */
5838 if (vr1
->type
== VR_ANTI_RANGE
)
5839 set_value_range (vr0
, vr1
->type
, vr1
->min
, vr1
->max
, vr0
->equiv
);
5841 /* The resulting set of equivalences is the intersection of
5843 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
5844 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
5845 else if (vr0
->equiv
&& !vr1
->equiv
)
5846 bitmap_clear (vr0
->equiv
);
5857 /* Failed to find an efficient meet. Before giving up and setting
5858 the result to VARYING, see if we can at least derive a useful
5859 anti-range. FIXME, all this nonsense about distinguishing
5860 anti-ranges from ranges is necessary because of the odd
5861 semantics of range_includes_zero_p and friends. */
5862 if (!symbolic_range_p (vr0
)
5863 && ((vr0
->type
== VR_RANGE
&& !range_includes_zero_p (vr0
))
5864 || (vr0
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr0
)))
5865 && !symbolic_range_p (vr1
)
5866 && ((vr1
->type
== VR_RANGE
&& !range_includes_zero_p (vr1
))
5867 || (vr1
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr1
))))
5869 set_value_range_to_nonnull (vr0
, TREE_TYPE (vr0
->min
));
5871 /* Since this meet operation did not result from the meeting of
5872 two equivalent names, VR0 cannot have any equivalences. */
5874 bitmap_clear (vr0
->equiv
);
5877 set_value_range_to_varying (vr0
);
5881 /* Visit all arguments for PHI node PHI that flow through executable
5882 edges. If a valid value range can be derived from all the incoming
5883 value ranges, set a new range for the LHS of PHI. */
5885 static enum ssa_prop_result
5886 vrp_visit_phi_node (tree phi
)
5889 tree lhs
= PHI_RESULT (phi
);
5890 value_range_t
*lhs_vr
= get_value_range (lhs
);
5891 value_range_t vr_result
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
5892 int edges
, old_edges
;
5894 copy_value_range (&vr_result
, lhs_vr
);
5896 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5898 fprintf (dump_file
, "\nVisiting PHI node: ");
5899 print_generic_expr (dump_file
, phi
, dump_flags
);
5903 for (i
= 0; i
< PHI_NUM_ARGS (phi
); i
++)
5905 edge e
= PHI_ARG_EDGE (phi
, i
);
5907 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5910 "\n Argument #%d (%d -> %d %sexecutable)\n",
5911 i
, e
->src
->index
, e
->dest
->index
,
5912 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
5915 if (e
->flags
& EDGE_EXECUTABLE
)
5917 tree arg
= PHI_ARG_DEF (phi
, i
);
5918 value_range_t vr_arg
;
5922 if (TREE_CODE (arg
) == SSA_NAME
)
5924 vr_arg
= *(get_value_range (arg
));
5928 if (is_overflow_infinity (arg
))
5930 arg
= copy_node (arg
);
5931 TREE_OVERFLOW (arg
) = 0;
5934 vr_arg
.type
= VR_RANGE
;
5937 vr_arg
.equiv
= NULL
;
5940 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5942 fprintf (dump_file
, "\t");
5943 print_generic_expr (dump_file
, arg
, dump_flags
);
5944 fprintf (dump_file
, "\n\tValue: ");
5945 dump_value_range (dump_file
, &vr_arg
);
5946 fprintf (dump_file
, "\n");
5949 vrp_meet (&vr_result
, &vr_arg
);
5951 if (vr_result
.type
== VR_VARYING
)
5956 if (vr_result
.type
== VR_VARYING
)
5959 old_edges
= vr_phi_edge_counts
[SSA_NAME_VERSION (lhs
)];
5960 vr_phi_edge_counts
[SSA_NAME_VERSION (lhs
)] = edges
;
5962 /* To prevent infinite iterations in the algorithm, derive ranges
5963 when the new value is slightly bigger or smaller than the
5964 previous one. We don't do this if we have seen a new executable
5965 edge; this helps us avoid an overflow infinity for conditionals
5966 which are not in a loop. */
5967 if (lhs_vr
->type
== VR_RANGE
&& vr_result
.type
== VR_RANGE
5968 && edges
<= old_edges
)
5970 if (!POINTER_TYPE_P (TREE_TYPE (lhs
)))
5972 int cmp_min
= compare_values (lhs_vr
->min
, vr_result
.min
);
5973 int cmp_max
= compare_values (lhs_vr
->max
, vr_result
.max
);
5975 /* If the new minimum is smaller or larger than the previous
5976 one, go all the way to -INF. In the first case, to avoid
5977 iterating millions of times to reach -INF, and in the
5978 other case to avoid infinite bouncing between different
5980 if (cmp_min
> 0 || cmp_min
< 0)
5982 /* If we will end up with a (-INF, +INF) range, set it
5984 if (vrp_val_is_max (vr_result
.max
))
5987 if (!needs_overflow_infinity (TREE_TYPE (vr_result
.min
))
5988 || !vrp_var_may_overflow (lhs
, phi
))
5989 vr_result
.min
= TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
));
5990 else if (supports_overflow_infinity (TREE_TYPE (vr_result
.min
)))
5992 negative_overflow_infinity (TREE_TYPE (vr_result
.min
));
5997 /* Similarly, if the new maximum is smaller or larger than
5998 the previous one, go all the way to +INF. */
5999 if (cmp_max
< 0 || cmp_max
> 0)
6001 /* If we will end up with a (-INF, +INF) range, set it
6003 if (vrp_val_is_min (vr_result
.min
))
6006 if (!needs_overflow_infinity (TREE_TYPE (vr_result
.max
))
6007 || !vrp_var_may_overflow (lhs
, phi
))
6008 vr_result
.max
= TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
));
6009 else if (supports_overflow_infinity (TREE_TYPE (vr_result
.max
)))
6011 positive_overflow_infinity (TREE_TYPE (vr_result
.max
));
6018 /* If the new range is different than the previous value, keep
6020 if (update_value_range (lhs
, &vr_result
))
6021 return SSA_PROP_INTERESTING
;
6023 /* Nothing changed, don't add outgoing edges. */
6024 return SSA_PROP_NOT_INTERESTING
;
6026 /* No match found. Set the LHS to VARYING. */
6028 set_value_range_to_varying (lhs_vr
);
6029 return SSA_PROP_VARYING
;
6032 /* Simplify a division or modulo operator to a right shift or
6033 bitwise and if the first operand is unsigned or is greater
6034 than zero and the second operand is an exact power of two. */
6037 simplify_div_or_mod_using_ranges (tree stmt
, tree rhs
, enum tree_code rhs_code
)
6040 tree op
= TREE_OPERAND (rhs
, 0);
6041 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
6043 if (TYPE_UNSIGNED (TREE_TYPE (op
)))
6045 val
= integer_one_node
;
6051 val
= compare_range_with_value (GE_EXPR
, vr
, integer_zero_node
, &sop
);
6055 && integer_onep (val
)
6056 && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC
))
6060 if (!EXPR_HAS_LOCATION (stmt
))
6061 locus
= input_location
;
6063 locus
= EXPR_LOCATION (stmt
);
6064 warning (OPT_Wstrict_overflow
,
6065 ("%Hassuming signed overflow does not occur when "
6066 "simplifying / or %% to >> or &"),
6071 if (val
&& integer_onep (val
))
6074 tree op0
= TREE_OPERAND (rhs
, 0);
6075 tree op1
= TREE_OPERAND (rhs
, 1);
6077 if (rhs_code
== TRUNC_DIV_EXPR
)
6079 t
= build_int_cst (NULL_TREE
, tree_log2 (op1
));
6080 t
= build2 (RSHIFT_EXPR
, TREE_TYPE (op0
), op0
, t
);
6084 t
= build_int_cst (TREE_TYPE (op1
), 1);
6085 t
= int_const_binop (MINUS_EXPR
, op1
, t
, 0);
6086 t
= fold_convert (TREE_TYPE (op0
), t
);
6087 t
= build2 (BIT_AND_EXPR
, TREE_TYPE (op0
), op0
, t
);
6090 GIMPLE_STMT_OPERAND (stmt
, 1) = t
;
6095 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
6096 ABS_EXPR. If the operand is <= 0, then simplify the
6097 ABS_EXPR into a NEGATE_EXPR. */
6100 simplify_abs_using_ranges (tree stmt
, tree rhs
)
6103 tree op
= TREE_OPERAND (rhs
, 0);
6104 tree type
= TREE_TYPE (op
);
6105 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
6107 if (TYPE_UNSIGNED (type
))
6109 val
= integer_zero_node
;
6115 val
= compare_range_with_value (LE_EXPR
, vr
, integer_zero_node
, &sop
);
6119 val
= compare_range_with_value (GE_EXPR
, vr
, integer_zero_node
,
6124 if (integer_zerop (val
))
6125 val
= integer_one_node
;
6126 else if (integer_onep (val
))
6127 val
= integer_zero_node
;
6132 && (integer_onep (val
) || integer_zerop (val
)))
6136 if (sop
&& issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC
))
6140 if (!EXPR_HAS_LOCATION (stmt
))
6141 locus
= input_location
;
6143 locus
= EXPR_LOCATION (stmt
);
6144 warning (OPT_Wstrict_overflow
,
6145 ("%Hassuming signed overflow does not occur when "
6146 "simplifying abs (X) to X or -X"),
6150 if (integer_onep (val
))
6151 t
= build1 (NEGATE_EXPR
, TREE_TYPE (op
), op
);
6155 GIMPLE_STMT_OPERAND (stmt
, 1) = t
;
6161 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
6162 a known value range VR.
6164 If there is one and only one value which will satisfy the
6165 conditional, then return that value. Else return NULL. */
6168 test_for_singularity (enum tree_code cond_code
, tree op0
,
6169 tree op1
, value_range_t
*vr
)
6174 /* Extract minimum/maximum values which satisfy the
6175 the conditional as it was written. */
6176 if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
6178 /* This should not be negative infinity; there is no overflow
6180 min
= TYPE_MIN_VALUE (TREE_TYPE (op0
));
6183 if (cond_code
== LT_EXPR
&& !is_overflow_infinity (max
))
6185 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
6186 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (op0
), max
, one
);
6188 TREE_NO_WARNING (max
) = 1;
6191 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
6193 /* This should not be positive infinity; there is no overflow
6195 max
= TYPE_MAX_VALUE (TREE_TYPE (op0
));
6198 if (cond_code
== GT_EXPR
&& !is_overflow_infinity (min
))
6200 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
6201 min
= fold_build2 (PLUS_EXPR
, TREE_TYPE (op0
), min
, one
);
6203 TREE_NO_WARNING (min
) = 1;
6207 /* Now refine the minimum and maximum values using any
6208 value range information we have for op0. */
6211 if (compare_values (vr
->min
, min
) == -1)
6215 if (compare_values (vr
->max
, max
) == 1)
6220 /* If the new min/max values have converged to a single value,
6221 then there is only one value which can satisfy the condition,
6222 return that value. */
6223 if (operand_equal_p (min
, max
, 0) && is_gimple_min_invariant (min
))
6229 /* Simplify a conditional using a relational operator to an equality
6230 test if the range information indicates only one value can satisfy
6231 the original conditional. */
6234 simplify_cond_using_ranges (tree stmt
)
6236 tree cond
= COND_EXPR_COND (stmt
);
6237 tree op0
= TREE_OPERAND (cond
, 0);
6238 tree op1
= TREE_OPERAND (cond
, 1);
6239 enum tree_code cond_code
= TREE_CODE (cond
);
6241 if (cond_code
!= NE_EXPR
6242 && cond_code
!= EQ_EXPR
6243 && TREE_CODE (op0
) == SSA_NAME
6244 && INTEGRAL_TYPE_P (TREE_TYPE (op0
))
6245 && is_gimple_min_invariant (op1
))
6247 value_range_t
*vr
= get_value_range (op0
);
6249 /* If we have range information for OP0, then we might be
6250 able to simplify this conditional. */
6251 if (vr
->type
== VR_RANGE
)
6253 tree
new = test_for_singularity (cond_code
, op0
, op1
, vr
);
6259 fprintf (dump_file
, "Simplified relational ");
6260 print_generic_expr (dump_file
, cond
, 0);
6261 fprintf (dump_file
, " into ");
6264 COND_EXPR_COND (stmt
)
6265 = build2 (EQ_EXPR
, boolean_type_node
, op0
, new);
6270 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
6271 fprintf (dump_file
, "\n");
6277 /* Try again after inverting the condition. We only deal
6278 with integral types here, so no need to worry about
6279 issues with inverting FP comparisons. */
6280 cond_code
= invert_tree_comparison (cond_code
, false);
6281 new = test_for_singularity (cond_code
, op0
, op1
, vr
);
6287 fprintf (dump_file
, "Simplified relational ");
6288 print_generic_expr (dump_file
, cond
, 0);
6289 fprintf (dump_file
, " into ");
6292 COND_EXPR_COND (stmt
)
6293 = build2 (NE_EXPR
, boolean_type_node
, op0
, new);
6298 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
6299 fprintf (dump_file
, "\n");
6308 /* Simplify a switch statement using the value range of the switch
6312 simplify_switch_using_ranges (tree stmt
)
6314 tree op
= TREE_OPERAND (stmt
, 0);
6319 size_t i
= 0, j
= 0, n
, n2
;
6323 if (TREE_CODE (op
) != SSA_NAME
)
6326 vr
= get_value_range (op
);
6328 /* We can only handle integer ranges. */
6329 if (vr
->type
!= VR_RANGE
6330 || symbolic_range_p (vr
))
6333 /* Find case label for min/max of the value range. */
6334 vec
= SWITCH_LABELS (stmt
);
6335 n
= TREE_VEC_LENGTH (vec
);
6336 take_default
= !find_case_label_range (vec
, vr
->min
, vr
->max
, &i
, &j
);
6338 /* Bail out if this is just all edges taken. */
6344 /* Build a new vector of taken case labels. */
6345 vec2
= make_tree_vec (j
- i
+ 1 + (int)take_default
);
6346 for (n2
= 0; i
<= j
; ++i
, ++n2
)
6347 TREE_VEC_ELT (vec2
, n2
) = TREE_VEC_ELT (vec
, i
);
6349 /* Add the default edge, if necessary. */
6351 TREE_VEC_ELT (vec2
, n2
++) = TREE_VEC_ELT (vec
, n
- 1);
6353 /* Mark needed edges. */
6354 for (i
= 0; i
< n2
; ++i
)
6356 e
= find_edge (bb_for_stmt (stmt
),
6357 label_to_block (CASE_LABEL (TREE_VEC_ELT (vec2
, i
))));
6358 e
->aux
= (void *)-1;
6361 /* Queue not needed edges for later removal. */
6362 FOR_EACH_EDGE (e
, ei
, bb_for_stmt (stmt
)->succs
)
6364 if (e
->aux
== (void *)-1)
6370 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
6372 fprintf (dump_file
, "removing unreachable case label\n");
6374 VEC_safe_push (edge
, heap
, to_remove_edges
, e
);
6377 /* And queue an update for the stmt. */
6380 VEC_safe_push (switch_update
, heap
, to_update_switch_stmts
, &su
);
6383 /* Simplify STMT using ranges if possible. */
6386 simplify_stmt_using_ranges (tree stmt
)
6388 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
6390 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
6391 enum tree_code rhs_code
= TREE_CODE (rhs
);
6393 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
6394 and BIT_AND_EXPR respectively if the first operand is greater
6395 than zero and the second operand is an exact power of two. */
6396 if ((rhs_code
== TRUNC_DIV_EXPR
|| rhs_code
== TRUNC_MOD_EXPR
)
6397 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0)))
6398 && integer_pow2p (TREE_OPERAND (rhs
, 1)))
6399 simplify_div_or_mod_using_ranges (stmt
, rhs
, rhs_code
);
6401 /* Transform ABS (X) into X or -X as appropriate. */
6402 if (rhs_code
== ABS_EXPR
6403 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == SSA_NAME
6404 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0))))
6405 simplify_abs_using_ranges (stmt
, rhs
);
6407 else if (TREE_CODE (stmt
) == COND_EXPR
6408 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt
)))
6409 simplify_cond_using_ranges (stmt
);
6410 else if (TREE_CODE (stmt
) == SWITCH_EXPR
)
6411 simplify_switch_using_ranges (stmt
);
6414 /* Stack of dest,src equivalency pairs that need to be restored after
6415 each attempt to thread a block's incoming edge to an outgoing edge.
6417 A NULL entry is used to mark the end of pairs which need to be
6419 static VEC(tree
,heap
) *stack
;
6421 /* A trivial wrapper so that we can present the generic jump threading
6422 code with a simple API for simplifying statements. STMT is the
6423 statement we want to simplify, WITHIN_STMT provides the location
6424 for any overflow warnings. */
6427 simplify_stmt_for_jump_threading (tree stmt
, tree within_stmt
)
6430 /* We only use VRP information to simplify conditionals. This is
6431 overly conservative, but it's unclear if doing more would be
6432 worth the compile time cost. */
6433 if (TREE_CODE (stmt
) != COND_EXPR
)
6436 conditional
= COND_EXPR_COND (stmt
);
6437 if (TREE_CODE (conditional
) == SSA_NAME
)
6438 return vrp_evaluate_conditional (EQ_EXPR
,
6443 return vrp_evaluate_conditional (TREE_CODE (conditional
),
6444 TREE_OPERAND (conditional
, 0),
6445 TREE_OPERAND (conditional
, 1),
6449 /* Blocks which have more than one predecessor and more than
6450 one successor present jump threading opportunities. ie,
6451 when the block is reached from a specific predecessor, we
6452 may be able to determine which of the outgoing edges will
6453 be traversed. When this optimization applies, we are able
6454 to avoid conditionals at runtime and we may expose secondary
6455 optimization opportunities.
6457 This routine is effectively a driver for the generic jump
6458 threading code. It basically just presents the generic code
6459 with edges that may be suitable for jump threading.
6461 Unlike DOM, we do not iterate VRP if jump threading was successful.
6462 While iterating may expose new opportunities for VRP, it is expected
6463 those opportunities would be very limited and the compile time cost
6464 to expose those opportunities would be significant.
6466 As jump threading opportunities are discovered, they are registered
6467 for later realization. */
6470 identify_jump_threads (void)
6477 /* Ugh. When substituting values earlier in this pass we can
6478 wipe the dominance information. So rebuild the dominator
6479 information as we need it within the jump threading code. */
6480 calculate_dominance_info (CDI_DOMINATORS
);
6482 /* We do not allow VRP information to be used for jump threading
6483 across a back edge in the CFG. Otherwise it becomes too
6484 difficult to avoid eliminating loop exit tests. Of course
6485 EDGE_DFS_BACK is not accurate at this time so we have to
6487 mark_dfs_back_edges ();
6489 /* Do not thread across edges we are about to remove. Just marking
6490 them as EDGE_DFS_BACK will do. */
6491 for (i
= 0; VEC_iterate (edge
, to_remove_edges
, i
, e
); ++i
)
6492 e
->flags
|= EDGE_DFS_BACK
;
6494 /* Allocate our unwinder stack to unwind any temporary equivalences
6495 that might be recorded. */
6496 stack
= VEC_alloc (tree
, heap
, 20);
6498 /* To avoid lots of silly node creation, we create a single
6499 conditional and just modify it in-place when attempting to
6501 dummy
= build2 (EQ_EXPR
, boolean_type_node
, NULL
, NULL
);
6502 dummy
= build3 (COND_EXPR
, void_type_node
, dummy
, NULL
, NULL
);
6504 /* Walk through all the blocks finding those which present a
6505 potential jump threading opportunity. We could set this up
6506 as a dominator walker and record data during the walk, but
6507 I doubt it's worth the effort for the classes of jump
6508 threading opportunities we are trying to identify at this
6509 point in compilation. */
6514 /* If the generic jump threading code does not find this block
6515 interesting, then there is nothing to do. */
6516 if (! potentially_threadable_block (bb
))
6519 /* We only care about blocks ending in a COND_EXPR. While there
6520 may be some value in handling SWITCH_EXPR here, I doubt it's
6521 terribly important. */
6522 last
= bsi_stmt (bsi_last (bb
));
6523 if (TREE_CODE (last
) != COND_EXPR
)
6526 /* We're basically looking for any kind of conditional with
6527 integral type arguments. */
6528 cond
= COND_EXPR_COND (last
);
6529 if ((TREE_CODE (cond
) == SSA_NAME
6530 && INTEGRAL_TYPE_P (TREE_TYPE (cond
)))
6531 || (COMPARISON_CLASS_P (cond
)
6532 && TREE_CODE (TREE_OPERAND (cond
, 0)) == SSA_NAME
6533 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond
, 0)))
6534 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == SSA_NAME
6535 || is_gimple_min_invariant (TREE_OPERAND (cond
, 1)))
6536 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond
, 1)))))
6540 /* We've got a block with multiple predecessors and multiple
6541 successors which also ends in a suitable conditional. For
6542 each predecessor, see if we can thread it to a specific
6544 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
6546 /* Do not thread across back edges or abnormal edges
6548 if (e
->flags
& (EDGE_DFS_BACK
| EDGE_COMPLEX
))
6551 thread_across_edge (dummy
, e
, true,
6553 simplify_stmt_for_jump_threading
);
6558 /* We do not actually update the CFG or SSA graphs at this point as
6559 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
6560 handle ASSERT_EXPRs gracefully. */
6563 /* We identified all the jump threading opportunities earlier, but could
6564 not transform the CFG at that time. This routine transforms the
6565 CFG and arranges for the dominator tree to be rebuilt if necessary.
6567 Note the SSA graph update will occur during the normal TODO
6568 processing by the pass manager. */
6570 finalize_jump_threads (void)
6572 thread_through_all_blocks (false);
6573 VEC_free (tree
, heap
, stack
);
6577 /* Traverse all the blocks folding conditionals with known ranges. */
6583 prop_value_t
*single_val_range
;
6584 bool do_value_subst_p
;
6588 fprintf (dump_file
, "\nValue ranges after VRP:\n\n");
6589 dump_all_value_ranges (dump_file
);
6590 fprintf (dump_file
, "\n");
6593 /* We may have ended with ranges that have exactly one value. Those
6594 values can be substituted as any other copy/const propagated
6595 value using substitute_and_fold. */
6596 single_val_range
= XCNEWVEC (prop_value_t
, num_ssa_names
);
6598 do_value_subst_p
= false;
6599 for (i
= 0; i
< num_ssa_names
; i
++)
6601 && vr_value
[i
]->type
== VR_RANGE
6602 && vr_value
[i
]->min
== vr_value
[i
]->max
)
6604 single_val_range
[i
].value
= vr_value
[i
]->min
;
6605 do_value_subst_p
= true;
6608 if (!do_value_subst_p
)
6610 /* We found no single-valued ranges, don't waste time trying to
6611 do single value substitution in substitute_and_fold. */
6612 free (single_val_range
);
6613 single_val_range
= NULL
;
6616 substitute_and_fold (single_val_range
, true);
6618 if (warn_array_bounds
)
6619 check_all_array_refs ();
6621 /* We must identify jump threading opportunities before we release
6622 the datastructures built by VRP. */
6623 identify_jump_threads ();
6625 /* Free allocated memory. */
6626 for (i
= 0; i
< num_ssa_names
; i
++)
6629 BITMAP_FREE (vr_value
[i
]->equiv
);
6633 free (single_val_range
);
6635 free (vr_phi_edge_counts
);
6637 /* So that we can distinguish between VRP data being available
6638 and not available. */
6640 vr_phi_edge_counts
= NULL
;
6643 /* Calculates number of iterations for all loops, to ensure that they are
6647 record_numbers_of_iterations (void)
6652 FOR_EACH_LOOP (li
, loop
, 0)
6654 number_of_latch_executions (loop
);
6658 /* Main entry point to VRP (Value Range Propagation). This pass is
6659 loosely based on J. R. C. Patterson, ``Accurate Static Branch
6660 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
6661 Programming Language Design and Implementation, pp. 67-78, 1995.
6662 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
6664 This is essentially an SSA-CCP pass modified to deal with ranges
6665 instead of constants.
6667 While propagating ranges, we may find that two or more SSA name
6668 have equivalent, though distinct ranges. For instance,
6671 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
6673 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
6677 In the code above, pointer p_5 has range [q_2, q_2], but from the
6678 code we can also determine that p_5 cannot be NULL and, if q_2 had
6679 a non-varying range, p_5's range should also be compatible with it.
6681 These equivalences are created by two expressions: ASSERT_EXPR and
6682 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
6683 result of another assertion, then we can use the fact that p_5 and
6684 p_4 are equivalent when evaluating p_5's range.
6686 Together with value ranges, we also propagate these equivalences
6687 between names so that we can take advantage of information from
6688 multiple ranges when doing final replacement. Note that this
6689 equivalency relation is transitive but not symmetric.
6691 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
6692 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
6693 in contexts where that assertion does not hold (e.g., in line 6).
6695 TODO, the main difference between this pass and Patterson's is that
6696 we do not propagate edge probabilities. We only compute whether
6697 edges can be taken or not. That is, instead of having a spectrum
6698 of jump probabilities between 0 and 1, we only deal with 0, 1 and
6699 DON'T KNOW. In the future, it may be worthwhile to propagate
6700 probabilities to aid branch prediction. */
6709 loop_optimizer_init (LOOPS_NORMAL
| LOOPS_HAVE_RECORDED_EXITS
);
6710 rewrite_into_loop_closed_ssa (NULL
, TODO_update_ssa
);
6713 insert_range_assertions ();
6715 /* Compute the # of iterations for each loop before we start the VRP
6716 analysis. The value ranges determined by VRP are used in expression
6717 simplification, that is also used by the # of iterations analysis.
6718 However, in the middle of the VRP analysis, the value ranges do not take
6719 all the possible paths in CFG into account, so they do not have to be
6720 correct, and the # of iterations analysis can obtain wrong results.
6721 This is a problem, since the results of the # of iterations analysis
6722 are cached, so these mistakes would not be corrected when the value
6723 ranges are corrected. */
6724 record_numbers_of_iterations ();
6726 to_remove_edges
= VEC_alloc (edge
, heap
, 10);
6727 to_update_switch_stmts
= VEC_alloc (switch_update
, heap
, 5);
6730 ssa_propagate (vrp_visit_stmt
, vrp_visit_phi_node
);
6733 /* ASSERT_EXPRs must be removed before finalizing jump threads
6734 as finalizing jump threads calls the CFG cleanup code which
6735 does not properly handle ASSERT_EXPRs. */
6736 remove_range_assertions ();
6738 /* If we exposed any new variables, go ahead and put them into
6739 SSA form now, before we handle jump threading. This simplifies
6740 interactions between rewriting of _DECL nodes into SSA form
6741 and rewriting SSA_NAME nodes into SSA form after block
6742 duplication and CFG manipulation. */
6743 update_ssa (TODO_update_ssa
);
6745 finalize_jump_threads ();
6747 /* Remove dead edges from SWITCH_EXPR optimization. This leaves the
6748 CFG in a broken state and requires a cfg_cleanup run. */
6749 for (i
= 0; VEC_iterate (edge
, to_remove_edges
, i
, e
); ++i
)
6751 /* Update SWITCH_EXPR case label vector. */
6752 for (i
= 0; VEC_iterate (switch_update
, to_update_switch_stmts
, i
, su
); ++i
)
6753 SWITCH_LABELS (su
->stmt
) = su
->vec
;
6755 if (VEC_length (edge
, to_remove_edges
) > 0)
6756 free_dominance_info (CDI_DOMINATORS
);
6758 VEC_free (edge
, heap
, to_remove_edges
);
6759 VEC_free (switch_update
, heap
, to_update_switch_stmts
);
6762 loop_optimizer_finalize ();
6770 return flag_tree_vrp
!= 0;
6773 struct gimple_opt_pass pass_vrp
=
6778 gate_vrp
, /* gate */
6779 execute_vrp
, /* execute */
6782 0, /* static_pass_number */
6783 TV_TREE_VRP
, /* tv_id */
6784 PROP_ssa
| PROP_alias
, /* properties_required */
6785 0, /* properties_provided */
6786 0, /* properties_destroyed */
6787 0, /* todo_flags_start */
6792 | TODO_update_ssa
/* todo_flags_finish */