1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
24 #include "coretypes.h"
29 #include "basic-block.h"
30 #include "tree-flow.h"
31 #include "tree-pass.h"
32 #include "tree-dump.h"
34 #include "diagnostic.h"
38 #include "tree-scalar-evolution.h"
39 #include "tree-ssa-propagate.h"
40 #include "tree-chrec.h"
42 /* Set of SSA names found during the dominator traversal of a
43 sub-graph in find_assert_locations. */
44 static sbitmap found_in_subgraph
;
46 /* Local functions. */
47 static int compare_values (tree val1
, tree val2
);
48 static int compare_values_warnv (tree val1
, tree val2
, bool *);
49 static void vrp_meet (value_range_t
*, value_range_t
*);
50 static tree
vrp_evaluate_conditional_warnv (tree
, bool, bool *);
52 /* Location information for ASSERT_EXPRs. Each instance of this
53 structure describes an ASSERT_EXPR for an SSA name. Since a single
54 SSA name may have more than one assertion associated with it, these
55 locations are kept in a linked list attached to the corresponding
59 /* Basic block where the assertion would be inserted. */
62 /* Some assertions need to be inserted on an edge (e.g., assertions
63 generated by COND_EXPRs). In those cases, BB will be NULL. */
66 /* Pointer to the statement that generated this assertion. */
67 block_stmt_iterator si
;
69 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
70 enum tree_code comp_code
;
72 /* Value being compared against. */
75 /* Next node in the linked list. */
76 struct assert_locus_d
*next
;
79 typedef struct assert_locus_d
*assert_locus_t
;
81 /* If bit I is present, it means that SSA name N_i has a list of
82 assertions that should be inserted in the IL. */
83 static bitmap need_assert_for
;
85 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
86 holds a list of ASSERT_LOCUS_T nodes that describe where
87 ASSERT_EXPRs for SSA name N_I should be inserted. */
88 static assert_locus_t
*asserts_for
;
90 /* Set of blocks visited in find_assert_locations. Used to avoid
91 visiting the same block more than once. */
92 static sbitmap blocks_visited
;
94 /* Value range array. After propagation, VR_VALUE[I] holds the range
95 of values that SSA name N_I may take. */
96 static value_range_t
**vr_value
;
98 /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the
99 number of executable edges we saw the last time we visited the
101 static int *vr_phi_edge_counts
;
104 /* Return whether TYPE should use an overflow infinity distinct from
105 TYPE_{MIN,MAX}_VALUE. We use an overflow infinity value to
106 represent a signed overflow during VRP computations. An infinity
107 is distinct from a half-range, which will go from some number to
108 TYPE_{MIN,MAX}_VALUE. */
111 needs_overflow_infinity (tree type
)
113 return INTEGRAL_TYPE_P (type
) && !TYPE_OVERFLOW_WRAPS (type
);
116 /* Return whether TYPE can support our overflow infinity
117 representation: we use the TREE_OVERFLOW flag, which only exists
118 for constants. If TYPE doesn't support this, we don't optimize
119 cases which would require signed overflow--we drop them to
123 supports_overflow_infinity (tree type
)
125 #ifdef ENABLE_CHECKING
126 gcc_assert (needs_overflow_infinity (type
));
128 return (TYPE_MIN_VALUE (type
) != NULL_TREE
129 && CONSTANT_CLASS_P (TYPE_MIN_VALUE (type
))
130 && TYPE_MAX_VALUE (type
) != NULL_TREE
131 && CONSTANT_CLASS_P (TYPE_MAX_VALUE (type
)));
134 /* VAL is the maximum or minimum value of a type. Return a
135 corresponding overflow infinity. */
138 make_overflow_infinity (tree val
)
140 #ifdef ENABLE_CHECKING
141 gcc_assert (val
!= NULL_TREE
&& CONSTANT_CLASS_P (val
));
143 val
= copy_node (val
);
144 TREE_OVERFLOW (val
) = 1;
148 /* Return a negative overflow infinity for TYPE. */
151 negative_overflow_infinity (tree type
)
153 #ifdef ENABLE_CHECKING
154 gcc_assert (supports_overflow_infinity (type
));
156 return make_overflow_infinity (TYPE_MIN_VALUE (type
));
159 /* Return a positive overflow infinity for TYPE. */
162 positive_overflow_infinity (tree type
)
164 #ifdef ENABLE_CHECKING
165 gcc_assert (supports_overflow_infinity (type
));
167 return make_overflow_infinity (TYPE_MAX_VALUE (type
));
170 /* Return whether VAL is a negative overflow infinity. */
173 is_negative_overflow_infinity (tree val
)
175 return (needs_overflow_infinity (TREE_TYPE (val
))
176 && CONSTANT_CLASS_P (val
)
177 && TREE_OVERFLOW (val
)
178 && operand_equal_p (val
, TYPE_MIN_VALUE (TREE_TYPE (val
)), 0));
181 /* Return whether VAL is a positive overflow infinity. */
184 is_positive_overflow_infinity (tree val
)
186 return (needs_overflow_infinity (TREE_TYPE (val
))
187 && CONSTANT_CLASS_P (val
)
188 && TREE_OVERFLOW (val
)
189 && operand_equal_p (val
, TYPE_MAX_VALUE (TREE_TYPE (val
)), 0));
192 /* Return whether VAL is a positive or negative overflow infinity. */
195 is_overflow_infinity (tree val
)
197 return (needs_overflow_infinity (TREE_TYPE (val
))
198 && CONSTANT_CLASS_P (val
)
199 && TREE_OVERFLOW (val
)
200 && (operand_equal_p (val
, TYPE_MAX_VALUE (TREE_TYPE (val
)), 0)
201 || operand_equal_p (val
, TYPE_MIN_VALUE (TREE_TYPE (val
)), 0)));
205 /* Return true if ARG is marked with the nonnull attribute in the
206 current function signature. */
209 nonnull_arg_p (tree arg
)
211 tree t
, attrs
, fntype
;
212 unsigned HOST_WIDE_INT arg_num
;
214 gcc_assert (TREE_CODE (arg
) == PARM_DECL
&& POINTER_TYPE_P (TREE_TYPE (arg
)));
216 /* The static chain decl is always non null. */
217 if (arg
== cfun
->static_chain_decl
)
220 fntype
= TREE_TYPE (current_function_decl
);
221 attrs
= lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype
));
223 /* If "nonnull" wasn't specified, we know nothing about the argument. */
224 if (attrs
== NULL_TREE
)
227 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
228 if (TREE_VALUE (attrs
) == NULL_TREE
)
231 /* Get the position number for ARG in the function signature. */
232 for (arg_num
= 1, t
= DECL_ARGUMENTS (current_function_decl
);
234 t
= TREE_CHAIN (t
), arg_num
++)
240 gcc_assert (t
== arg
);
242 /* Now see if ARG_NUM is mentioned in the nonnull list. */
243 for (t
= TREE_VALUE (attrs
); t
; t
= TREE_CHAIN (t
))
245 if (compare_tree_int (TREE_VALUE (t
), arg_num
) == 0)
253 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
256 set_value_range (value_range_t
*vr
, enum value_range_type t
, tree min
,
257 tree max
, bitmap equiv
)
259 #if defined ENABLE_CHECKING
260 /* Check the validity of the range. */
261 if (t
== VR_RANGE
|| t
== VR_ANTI_RANGE
)
265 gcc_assert (min
&& max
);
267 if (INTEGRAL_TYPE_P (TREE_TYPE (min
)) && t
== VR_ANTI_RANGE
)
268 gcc_assert ((min
!= TYPE_MIN_VALUE (TREE_TYPE (min
))
269 && !is_negative_overflow_infinity (min
))
270 || (max
!= TYPE_MAX_VALUE (TREE_TYPE (max
))
271 && !is_positive_overflow_infinity (max
)));
273 cmp
= compare_values (min
, max
);
274 gcc_assert (cmp
== 0 || cmp
== -1 || cmp
== -2);
277 if (t
== VR_UNDEFINED
|| t
== VR_VARYING
)
278 gcc_assert (min
== NULL_TREE
&& max
== NULL_TREE
);
280 if (t
== VR_UNDEFINED
|| t
== VR_VARYING
)
281 gcc_assert (equiv
== NULL
|| bitmap_empty_p (equiv
));
288 /* Since updating the equivalence set involves deep copying the
289 bitmaps, only do it if absolutely necessary. */
290 if (vr
->equiv
== NULL
)
291 vr
->equiv
= BITMAP_ALLOC (NULL
);
293 if (equiv
!= vr
->equiv
)
295 if (equiv
&& !bitmap_empty_p (equiv
))
296 bitmap_copy (vr
->equiv
, equiv
);
298 bitmap_clear (vr
->equiv
);
303 /* Copy value range FROM into value range TO. */
306 copy_value_range (value_range_t
*to
, value_range_t
*from
)
308 set_value_range (to
, from
->type
, from
->min
, from
->max
, from
->equiv
);
312 /* Set value range VR to VR_VARYING. */
315 set_value_range_to_varying (value_range_t
*vr
)
317 vr
->type
= VR_VARYING
;
318 vr
->min
= vr
->max
= NULL_TREE
;
320 bitmap_clear (vr
->equiv
);
323 /* Set value range VR to a non-negative range of type TYPE.
324 OVERFLOW_INFINITY indicates whether to use a overflow infinity
325 rather than TYPE_MAX_VALUE; this should be true if we determine
326 that the range is nonnegative based on the assumption that signed
327 overflow does not occur. */
330 set_value_range_to_nonnegative (value_range_t
*vr
, tree type
,
331 bool overflow_infinity
)
335 if (overflow_infinity
&& !supports_overflow_infinity (type
))
337 set_value_range_to_varying (vr
);
341 zero
= build_int_cst (type
, 0);
342 set_value_range (vr
, VR_RANGE
, zero
,
344 ? positive_overflow_infinity (type
)
345 : TYPE_MAX_VALUE (type
)),
349 /* Set value range VR to a non-NULL range of type TYPE. */
352 set_value_range_to_nonnull (value_range_t
*vr
, tree type
)
354 tree zero
= build_int_cst (type
, 0);
355 set_value_range (vr
, VR_ANTI_RANGE
, zero
, zero
, vr
->equiv
);
359 /* Set value range VR to a NULL range of type TYPE. */
362 set_value_range_to_null (value_range_t
*vr
, tree type
)
364 tree zero
= build_int_cst (type
, 0);
365 set_value_range (vr
, VR_RANGE
, zero
, zero
, vr
->equiv
);
369 /* Set value range VR to a range of a truthvalue of type TYPE. */
372 set_value_range_to_truthvalue (value_range_t
*vr
, tree type
)
374 if (TYPE_PRECISION (type
) == 1)
375 set_value_range_to_varying (vr
);
377 set_value_range (vr
, VR_RANGE
,
378 build_int_cst (type
, 0), build_int_cst (type
, 1),
383 /* Set value range VR to VR_UNDEFINED. */
386 set_value_range_to_undefined (value_range_t
*vr
)
388 vr
->type
= VR_UNDEFINED
;
389 vr
->min
= vr
->max
= NULL_TREE
;
391 bitmap_clear (vr
->equiv
);
395 /* Return value range information for VAR.
397 If we have no values ranges recorded (ie, VRP is not running), then
398 return NULL. Otherwise create an empty range if none existed for VAR. */
400 static value_range_t
*
401 get_value_range (tree var
)
405 unsigned ver
= SSA_NAME_VERSION (var
);
407 /* If we have no recorded ranges, then return NULL. */
415 /* Create a default value range. */
416 vr_value
[ver
] = vr
= XCNEW (value_range_t
);
418 /* Allocate an equivalence set. */
419 vr
->equiv
= BITMAP_ALLOC (NULL
);
421 /* If VAR is a default definition, the variable can take any value
423 sym
= SSA_NAME_VAR (var
);
424 if (SSA_NAME_IS_DEFAULT_DEF (var
))
426 /* Try to use the "nonnull" attribute to create ~[0, 0]
427 anti-ranges for pointers. Note that this is only valid with
428 default definitions of PARM_DECLs. */
429 if (TREE_CODE (sym
) == PARM_DECL
430 && POINTER_TYPE_P (TREE_TYPE (sym
))
431 && nonnull_arg_p (sym
))
432 set_value_range_to_nonnull (vr
, TREE_TYPE (sym
));
434 set_value_range_to_varying (vr
);
440 /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */
443 vrp_operand_equal_p (tree val1
, tree val2
)
447 if (!val1
|| !val2
|| !operand_equal_p (val1
, val2
, 0))
449 if (is_overflow_infinity (val1
))
450 return is_overflow_infinity (val2
);
454 /* Return true, if the bitmaps B1 and B2 are equal. */
457 vrp_bitmap_equal_p (bitmap b1
, bitmap b2
)
461 && bitmap_equal_p (b1
, b2
)));
464 /* Update the value range and equivalence set for variable VAR to
465 NEW_VR. Return true if NEW_VR is different from VAR's previous
468 NOTE: This function assumes that NEW_VR is a temporary value range
469 object created for the sole purpose of updating VAR's range. The
470 storage used by the equivalence set from NEW_VR will be freed by
471 this function. Do not call update_value_range when NEW_VR
472 is the range object associated with another SSA name. */
475 update_value_range (tree var
, value_range_t
*new_vr
)
477 value_range_t
*old_vr
;
480 /* Update the value range, if necessary. */
481 old_vr
= get_value_range (var
);
482 is_new
= old_vr
->type
!= new_vr
->type
483 || !vrp_operand_equal_p (old_vr
->min
, new_vr
->min
)
484 || !vrp_operand_equal_p (old_vr
->max
, new_vr
->max
)
485 || !vrp_bitmap_equal_p (old_vr
->equiv
, new_vr
->equiv
);
488 set_value_range (old_vr
, new_vr
->type
, new_vr
->min
, new_vr
->max
,
491 BITMAP_FREE (new_vr
->equiv
);
492 new_vr
->equiv
= NULL
;
498 /* Add VAR and VAR's equivalence set to EQUIV. */
501 add_equivalence (bitmap equiv
, tree var
)
503 unsigned ver
= SSA_NAME_VERSION (var
);
504 value_range_t
*vr
= vr_value
[ver
];
506 bitmap_set_bit (equiv
, ver
);
508 bitmap_ior_into (equiv
, vr
->equiv
);
512 /* Return true if VR is ~[0, 0]. */
515 range_is_nonnull (value_range_t
*vr
)
517 return vr
->type
== VR_ANTI_RANGE
518 && integer_zerop (vr
->min
)
519 && integer_zerop (vr
->max
);
523 /* Return true if VR is [0, 0]. */
526 range_is_null (value_range_t
*vr
)
528 return vr
->type
== VR_RANGE
529 && integer_zerop (vr
->min
)
530 && integer_zerop (vr
->max
);
534 /* Return true if value range VR involves at least one symbol. */
537 symbolic_range_p (value_range_t
*vr
)
539 return (!is_gimple_min_invariant (vr
->min
)
540 || !is_gimple_min_invariant (vr
->max
));
543 /* Return true if value range VR uses a overflow infinity. */
546 overflow_infinity_range_p (value_range_t
*vr
)
548 return (vr
->type
== VR_RANGE
549 && (is_overflow_infinity (vr
->min
)
550 || is_overflow_infinity (vr
->max
)));
553 /* Return false if we can not make a valid comparison based on VR;
554 this will be the case if it uses an overflow infinity and overflow
555 is not undefined (i.e., -fno-strict-overflow is in effect).
556 Otherwise return true, and set *STRICT_OVERFLOW_P to true if VR
557 uses an overflow infinity. */
560 usable_range_p (value_range_t
*vr
, bool *strict_overflow_p
)
562 gcc_assert (vr
->type
== VR_RANGE
);
563 if (is_overflow_infinity (vr
->min
))
565 *strict_overflow_p
= true;
566 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr
->min
)))
569 if (is_overflow_infinity (vr
->max
))
571 *strict_overflow_p
= true;
572 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr
->max
)))
579 /* Like tree_expr_nonnegative_warnv_p, but this function uses value
580 ranges obtained so far. */
583 vrp_expr_computes_nonnegative (tree expr
, bool *strict_overflow_p
)
585 return tree_expr_nonnegative_warnv_p (expr
, strict_overflow_p
);
588 /* Like tree_expr_nonzero_warnv_p, but this function uses value ranges
592 vrp_expr_computes_nonzero (tree expr
, bool *strict_overflow_p
)
594 if (tree_expr_nonzero_warnv_p (expr
, strict_overflow_p
))
597 /* If we have an expression of the form &X->a, then the expression
598 is nonnull if X is nonnull. */
599 if (TREE_CODE (expr
) == ADDR_EXPR
)
601 tree base
= get_base_address (TREE_OPERAND (expr
, 0));
603 if (base
!= NULL_TREE
604 && TREE_CODE (base
) == INDIRECT_REF
605 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
607 value_range_t
*vr
= get_value_range (TREE_OPERAND (base
, 0));
608 if (range_is_nonnull (vr
))
616 /* Returns true if EXPR is a valid value (as expected by compare_values) --
617 a gimple invariant, or SSA_NAME +- CST. */
620 valid_value_p (tree expr
)
622 if (TREE_CODE (expr
) == SSA_NAME
)
625 if (TREE_CODE (expr
) == PLUS_EXPR
626 || TREE_CODE (expr
) == MINUS_EXPR
)
627 return (TREE_CODE (TREE_OPERAND (expr
, 0)) == SSA_NAME
628 && TREE_CODE (TREE_OPERAND (expr
, 1)) == INTEGER_CST
);
630 return is_gimple_min_invariant (expr
);
636 -2 if those are incomparable. */
638 operand_less_p (tree val
, tree val2
)
640 /* LT is folded faster than GE and others. Inline the common case. */
641 if (TREE_CODE (val
) == INTEGER_CST
&& TREE_CODE (val2
) == INTEGER_CST
)
643 if (TYPE_UNSIGNED (TREE_TYPE (val
)))
644 return INT_CST_LT_UNSIGNED (val
, val2
);
647 if (INT_CST_LT (val
, val2
))
655 fold_defer_overflow_warnings ();
657 tcmp
= fold_binary_to_constant (LT_EXPR
, boolean_type_node
, val
, val2
);
659 fold_undefer_and_ignore_overflow_warnings ();
664 if (!integer_zerop (tcmp
))
668 /* val >= val2, not considering overflow infinity. */
669 if (is_negative_overflow_infinity (val
))
670 return is_negative_overflow_infinity (val2
) ? 0 : 1;
671 else if (is_positive_overflow_infinity (val2
))
672 return is_positive_overflow_infinity (val
) ? 0 : 1;
677 /* Compare two values VAL1 and VAL2. Return
679 -2 if VAL1 and VAL2 cannot be compared at compile-time,
682 +1 if VAL1 > VAL2, and
685 This is similar to tree_int_cst_compare but supports pointer values
686 and values that cannot be compared at compile time.
688 If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to
689 true if the return value is only valid if we assume that signed
690 overflow is undefined. */
693 compare_values_warnv (tree val1
, tree val2
, bool *strict_overflow_p
)
698 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
700 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1
))
701 == POINTER_TYPE_P (TREE_TYPE (val2
)));
703 if ((TREE_CODE (val1
) == SSA_NAME
704 || TREE_CODE (val1
) == PLUS_EXPR
705 || TREE_CODE (val1
) == MINUS_EXPR
)
706 && (TREE_CODE (val2
) == SSA_NAME
707 || TREE_CODE (val2
) == PLUS_EXPR
708 || TREE_CODE (val2
) == MINUS_EXPR
))
711 enum tree_code code1
, code2
;
713 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
714 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
715 same name, return -2. */
716 if (TREE_CODE (val1
) == SSA_NAME
)
724 code1
= TREE_CODE (val1
);
725 n1
= TREE_OPERAND (val1
, 0);
726 c1
= TREE_OPERAND (val1
, 1);
727 if (tree_int_cst_sgn (c1
) == -1)
729 if (is_negative_overflow_infinity (c1
))
731 c1
= fold_unary_to_constant (NEGATE_EXPR
, TREE_TYPE (c1
), c1
);
734 code1
= code1
== MINUS_EXPR
? PLUS_EXPR
: MINUS_EXPR
;
738 if (TREE_CODE (val2
) == SSA_NAME
)
746 code2
= TREE_CODE (val2
);
747 n2
= TREE_OPERAND (val2
, 0);
748 c2
= TREE_OPERAND (val2
, 1);
749 if (tree_int_cst_sgn (c2
) == -1)
751 if (is_negative_overflow_infinity (c2
))
753 c2
= fold_unary_to_constant (NEGATE_EXPR
, TREE_TYPE (c2
), c2
);
756 code2
= code2
== MINUS_EXPR
? PLUS_EXPR
: MINUS_EXPR
;
760 /* Both values must use the same name. */
764 if (code1
== SSA_NAME
765 && code2
== SSA_NAME
)
769 /* If overflow is defined we cannot simplify more. */
770 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1
)))
773 if (strict_overflow_p
!= NULL
)
774 *strict_overflow_p
= true;
776 if (code1
== SSA_NAME
)
778 if (code2
== PLUS_EXPR
)
779 /* NAME < NAME + CST */
781 else if (code2
== MINUS_EXPR
)
782 /* NAME > NAME - CST */
785 else if (code1
== PLUS_EXPR
)
787 if (code2
== SSA_NAME
)
788 /* NAME + CST > NAME */
790 else if (code2
== PLUS_EXPR
)
791 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
792 return compare_values_warnv (c1
, c2
, strict_overflow_p
);
793 else if (code2
== MINUS_EXPR
)
794 /* NAME + CST1 > NAME - CST2 */
797 else if (code1
== MINUS_EXPR
)
799 if (code2
== SSA_NAME
)
800 /* NAME - CST < NAME */
802 else if (code2
== PLUS_EXPR
)
803 /* NAME - CST1 < NAME + CST2 */
805 else if (code2
== MINUS_EXPR
)
806 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
807 C1 and C2 are swapped in the call to compare_values. */
808 return compare_values_warnv (c2
, c1
, strict_overflow_p
);
814 /* We cannot compare non-constants. */
815 if (!is_gimple_min_invariant (val1
) || !is_gimple_min_invariant (val2
))
818 if (!POINTER_TYPE_P (TREE_TYPE (val1
)))
820 /* We cannot compare overflowed values, except for overflow
822 if (TREE_OVERFLOW (val1
) || TREE_OVERFLOW (val2
))
824 if (strict_overflow_p
!= NULL
)
825 *strict_overflow_p
= true;
826 if (is_negative_overflow_infinity (val1
))
827 return is_negative_overflow_infinity (val2
) ? 0 : -1;
828 else if (is_negative_overflow_infinity (val2
))
830 else if (is_positive_overflow_infinity (val1
))
831 return is_positive_overflow_infinity (val2
) ? 0 : 1;
832 else if (is_positive_overflow_infinity (val2
))
837 return tree_int_cst_compare (val1
, val2
);
843 /* First see if VAL1 and VAL2 are not the same. */
844 if (val1
== val2
|| operand_equal_p (val1
, val2
, 0))
847 /* If VAL1 is a lower address than VAL2, return -1. */
848 if (operand_less_p (val1
, val2
) == 1)
851 /* If VAL1 is a higher address than VAL2, return +1. */
852 if (operand_less_p (val2
, val1
) == 1)
855 /* If VAL1 is different than VAL2, return +2.
856 For integer constants we either have already returned -1 or 1
857 or they are equivalent. We still might succeed in proving
858 something about non-trivial operands. */
859 if (TREE_CODE (val1
) != INTEGER_CST
860 || TREE_CODE (val2
) != INTEGER_CST
)
862 t
= fold_binary_to_constant (NE_EXPR
, boolean_type_node
, val1
, val2
);
863 if (t
&& tree_expr_nonzero_p (t
))
871 /* Compare values like compare_values_warnv, but treat comparisons of
872 nonconstants which rely on undefined overflow as incomparable. */
875 compare_values (tree val1
, tree val2
)
881 ret
= compare_values_warnv (val1
, val2
, &sop
);
883 && (!is_gimple_min_invariant (val1
) || !is_gimple_min_invariant (val2
)))
889 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
890 0 if VAL is not inside VR,
891 -2 if we cannot tell either way.
893 FIXME, the current semantics of this functions are a bit quirky
894 when taken in the context of VRP. In here we do not care
895 about VR's type. If VR is the anti-range ~[3, 5] the call
896 value_inside_range (4, VR) will return 1.
898 This is counter-intuitive in a strict sense, but the callers
899 currently expect this. They are calling the function
900 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
901 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
904 This also applies to value_ranges_intersect_p and
905 range_includes_zero_p. The semantics of VR_RANGE and
906 VR_ANTI_RANGE should be encoded here, but that also means
907 adapting the users of these functions to the new semantics.
909 Benchmark compile/20001226-1.c compilation time after changing this
913 value_inside_range (tree val
, value_range_t
* vr
)
917 cmp1
= operand_less_p (val
, vr
->min
);
923 cmp2
= operand_less_p (vr
->max
, val
);
931 /* Return true if value ranges VR0 and VR1 have a non-empty
934 Benchmark compile/20001226-1.c compilation time after changing this
939 value_ranges_intersect_p (value_range_t
*vr0
, value_range_t
*vr1
)
941 /* The value ranges do not intersect if the maximum of the first range is
942 less than the minimum of the second range or vice versa.
943 When those relations are unknown, we can't do any better. */
944 if (operand_less_p (vr0
->max
, vr1
->min
) != 0)
946 if (operand_less_p (vr1
->max
, vr0
->min
) != 0)
952 /* Return true if VR includes the value zero, false otherwise. FIXME,
953 currently this will return false for an anti-range like ~[-4, 3].
954 This will be wrong when the semantics of value_inside_range are
955 modified (currently the users of this function expect these
959 range_includes_zero_p (value_range_t
*vr
)
963 gcc_assert (vr
->type
!= VR_UNDEFINED
964 && vr
->type
!= VR_VARYING
965 && !symbolic_range_p (vr
));
967 zero
= build_int_cst (TREE_TYPE (vr
->min
), 0);
968 return (value_inside_range (zero
, vr
) == 1);
971 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
972 false otherwise or if no value range information is available. */
975 ssa_name_nonnegative_p (tree t
)
977 value_range_t
*vr
= get_value_range (t
);
982 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
983 which would return a useful value should be encoded as a VR_RANGE. */
984 if (vr
->type
== VR_RANGE
)
986 int result
= compare_values (vr
->min
, integer_zero_node
);
988 return (result
== 0 || result
== 1);
993 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
994 false otherwise or if no value range information is available. */
997 ssa_name_nonzero_p (tree t
)
999 value_range_t
*vr
= get_value_range (t
);
1004 /* A VR_RANGE which does not include zero is a nonzero value. */
1005 if (vr
->type
== VR_RANGE
&& !symbolic_range_p (vr
))
1006 return ! range_includes_zero_p (vr
);
1008 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
1009 if (vr
->type
== VR_ANTI_RANGE
&& !symbolic_range_p (vr
))
1010 return range_includes_zero_p (vr
);
1016 /* Extract value range information from an ASSERT_EXPR EXPR and store
1020 extract_range_from_assert (value_range_t
*vr_p
, tree expr
)
1022 tree var
, cond
, limit
, min
, max
, type
;
1023 value_range_t
*var_vr
, *limit_vr
;
1024 enum tree_code cond_code
;
1026 var
= ASSERT_EXPR_VAR (expr
);
1027 cond
= ASSERT_EXPR_COND (expr
);
1029 gcc_assert (COMPARISON_CLASS_P (cond
));
1031 /* Find VAR in the ASSERT_EXPR conditional. */
1032 if (var
== TREE_OPERAND (cond
, 0))
1034 /* If the predicate is of the form VAR COMP LIMIT, then we just
1035 take LIMIT from the RHS and use the same comparison code. */
1036 limit
= TREE_OPERAND (cond
, 1);
1037 cond_code
= TREE_CODE (cond
);
1041 /* If the predicate is of the form LIMIT COMP VAR, then we need
1042 to flip around the comparison code to create the proper range
1044 limit
= TREE_OPERAND (cond
, 0);
1045 cond_code
= swap_tree_comparison (TREE_CODE (cond
));
1048 type
= TREE_TYPE (limit
);
1049 gcc_assert (limit
!= var
);
1051 /* For pointer arithmetic, we only keep track of pointer equality
1053 if (POINTER_TYPE_P (type
) && cond_code
!= NE_EXPR
&& cond_code
!= EQ_EXPR
)
1055 set_value_range_to_varying (vr_p
);
1059 /* If LIMIT is another SSA name and LIMIT has a range of its own,
1060 try to use LIMIT's range to avoid creating symbolic ranges
1062 limit_vr
= (TREE_CODE (limit
) == SSA_NAME
) ? get_value_range (limit
) : NULL
;
1064 /* LIMIT's range is only interesting if it has any useful information. */
1066 && (limit_vr
->type
== VR_UNDEFINED
1067 || limit_vr
->type
== VR_VARYING
1068 || symbolic_range_p (limit_vr
)))
1071 /* Initially, the new range has the same set of equivalences of
1072 VAR's range. This will be revised before returning the final
1073 value. Since assertions may be chained via mutually exclusive
1074 predicates, we will need to trim the set of equivalences before
1076 gcc_assert (vr_p
->equiv
== NULL
);
1077 vr_p
->equiv
= BITMAP_ALLOC (NULL
);
1078 add_equivalence (vr_p
->equiv
, var
);
1080 /* Extract a new range based on the asserted comparison for VAR and
1081 LIMIT's value range. Notice that if LIMIT has an anti-range, we
1082 will only use it for equality comparisons (EQ_EXPR). For any
1083 other kind of assertion, we cannot derive a range from LIMIT's
1084 anti-range that can be used to describe the new range. For
1085 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
1086 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
1087 no single range for x_2 that could describe LE_EXPR, so we might
1088 as well build the range [b_4, +INF] for it. */
1089 if (cond_code
== EQ_EXPR
)
1091 enum value_range_type range_type
;
1095 range_type
= limit_vr
->type
;
1096 min
= limit_vr
->min
;
1097 max
= limit_vr
->max
;
1101 range_type
= VR_RANGE
;
1106 set_value_range (vr_p
, range_type
, min
, max
, vr_p
->equiv
);
1108 /* When asserting the equality VAR == LIMIT and LIMIT is another
1109 SSA name, the new range will also inherit the equivalence set
1111 if (TREE_CODE (limit
) == SSA_NAME
)
1112 add_equivalence (vr_p
->equiv
, limit
);
1114 else if (cond_code
== NE_EXPR
)
1116 /* As described above, when LIMIT's range is an anti-range and
1117 this assertion is an inequality (NE_EXPR), then we cannot
1118 derive anything from the anti-range. For instance, if
1119 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
1120 not imply that VAR's range is [0, 0]. So, in the case of
1121 anti-ranges, we just assert the inequality using LIMIT and
1124 If LIMIT_VR is a range, we can only use it to build a new
1125 anti-range if LIMIT_VR is a single-valued range. For
1126 instance, if LIMIT_VR is [0, 1], the predicate
1127 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
1128 Rather, it means that for value 0 VAR should be ~[0, 0]
1129 and for value 1, VAR should be ~[1, 1]. We cannot
1130 represent these ranges.
1132 The only situation in which we can build a valid
1133 anti-range is when LIMIT_VR is a single-valued range
1134 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
1135 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
1137 && limit_vr
->type
== VR_RANGE
1138 && compare_values (limit_vr
->min
, limit_vr
->max
) == 0)
1140 min
= limit_vr
->min
;
1141 max
= limit_vr
->max
;
1145 /* In any other case, we cannot use LIMIT's range to build a
1146 valid anti-range. */
1150 /* If MIN and MAX cover the whole range for their type, then
1151 just use the original LIMIT. */
1152 if (INTEGRAL_TYPE_P (type
)
1153 && (min
== TYPE_MIN_VALUE (type
)
1154 || is_negative_overflow_infinity (min
))
1155 && (max
== TYPE_MAX_VALUE (type
)
1156 || is_positive_overflow_infinity (max
)))
1159 set_value_range (vr_p
, VR_ANTI_RANGE
, min
, max
, vr_p
->equiv
);
1161 else if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
1163 min
= TYPE_MIN_VALUE (type
);
1165 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
1169 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1170 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
1172 max
= limit_vr
->max
;
1175 /* If the maximum value forces us to be out of bounds, simply punt.
1176 It would be pointless to try and do anything more since this
1177 all should be optimized away above us. */
1178 if ((cond_code
== LT_EXPR
1179 && compare_values (max
, min
) == 0)
1180 || is_overflow_infinity (max
))
1181 set_value_range_to_varying (vr_p
);
1184 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
1185 if (cond_code
== LT_EXPR
)
1187 tree one
= build_int_cst (type
, 1);
1188 max
= fold_build2 (MINUS_EXPR
, type
, max
, one
);
1191 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1194 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
1196 max
= TYPE_MAX_VALUE (type
);
1198 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
1202 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1203 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
1205 min
= limit_vr
->min
;
1208 /* If the minimum value forces us to be out of bounds, simply punt.
1209 It would be pointless to try and do anything more since this
1210 all should be optimized away above us. */
1211 if ((cond_code
== GT_EXPR
1212 && compare_values (min
, max
) == 0)
1213 || is_overflow_infinity (min
))
1214 set_value_range_to_varying (vr_p
);
1217 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
1218 if (cond_code
== GT_EXPR
)
1220 tree one
= build_int_cst (type
, 1);
1221 min
= fold_build2 (PLUS_EXPR
, type
, min
, one
);
1224 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1230 /* If VAR already had a known range, it may happen that the new
1231 range we have computed and VAR's range are not compatible. For
1235 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
1237 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
1239 While the above comes from a faulty program, it will cause an ICE
1240 later because p_8 and p_6 will have incompatible ranges and at
1241 the same time will be considered equivalent. A similar situation
1245 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
1247 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
1249 Again i_6 and i_7 will have incompatible ranges. It would be
1250 pointless to try and do anything with i_7's range because
1251 anything dominated by 'if (i_5 < 5)' will be optimized away.
1252 Note, due to the wa in which simulation proceeds, the statement
1253 i_7 = ASSERT_EXPR <...> we would never be visited because the
1254 conditional 'if (i_5 < 5)' always evaluates to false. However,
1255 this extra check does not hurt and may protect against future
1256 changes to VRP that may get into a situation similar to the
1257 NULL pointer dereference example.
1259 Note that these compatibility tests are only needed when dealing
1260 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1261 are both anti-ranges, they will always be compatible, because two
1262 anti-ranges will always have a non-empty intersection. */
1264 var_vr
= get_value_range (var
);
1266 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1267 ranges or anti-ranges. */
1268 if (vr_p
->type
== VR_VARYING
1269 || vr_p
->type
== VR_UNDEFINED
1270 || var_vr
->type
== VR_VARYING
1271 || var_vr
->type
== VR_UNDEFINED
1272 || symbolic_range_p (vr_p
)
1273 || symbolic_range_p (var_vr
))
1276 if (var_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_RANGE
)
1278 /* If the two ranges have a non-empty intersection, we can
1279 refine the resulting range. Since the assert expression
1280 creates an equivalency and at the same time it asserts a
1281 predicate, we can take the intersection of the two ranges to
1282 get better precision. */
1283 if (value_ranges_intersect_p (var_vr
, vr_p
))
1285 /* Use the larger of the two minimums. */
1286 if (compare_values (vr_p
->min
, var_vr
->min
) == -1)
1291 /* Use the smaller of the two maximums. */
1292 if (compare_values (vr_p
->max
, var_vr
->max
) == 1)
1297 set_value_range (vr_p
, vr_p
->type
, min
, max
, vr_p
->equiv
);
1301 /* The two ranges do not intersect, set the new range to
1302 VARYING, because we will not be able to do anything
1303 meaningful with it. */
1304 set_value_range_to_varying (vr_p
);
1307 else if ((var_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_ANTI_RANGE
)
1308 || (var_vr
->type
== VR_ANTI_RANGE
&& vr_p
->type
== VR_RANGE
))
1310 /* A range and an anti-range will cancel each other only if
1311 their ends are the same. For instance, in the example above,
1312 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1313 so VR_P should be set to VR_VARYING. */
1314 if (compare_values (var_vr
->min
, vr_p
->min
) == 0
1315 && compare_values (var_vr
->max
, vr_p
->max
) == 0)
1316 set_value_range_to_varying (vr_p
);
1319 tree min
, max
, anti_min
, anti_max
, real_min
, real_max
;
1322 /* We want to compute the logical AND of the two ranges;
1323 there are three cases to consider.
1326 1. The VR_ANTI_RANGE range is completely within the
1327 VR_RANGE and the endpoints of the ranges are
1328 different. In that case the resulting range
1329 should be whichever range is more precise.
1330 Typically that will be the VR_RANGE.
1332 2. The VR_ANTI_RANGE is completely disjoint from
1333 the VR_RANGE. In this case the resulting range
1334 should be the VR_RANGE.
1336 3. There is some overlap between the VR_ANTI_RANGE
1339 3a. If the high limit of the VR_ANTI_RANGE resides
1340 within the VR_RANGE, then the result is a new
1341 VR_RANGE starting at the high limit of the
1342 the VR_ANTI_RANGE + 1 and extending to the
1343 high limit of the original VR_RANGE.
1345 3b. If the low limit of the VR_ANTI_RANGE resides
1346 within the VR_RANGE, then the result is a new
1347 VR_RANGE starting at the low limit of the original
1348 VR_RANGE and extending to the low limit of the
1349 VR_ANTI_RANGE - 1. */
1350 if (vr_p
->type
== VR_ANTI_RANGE
)
1352 anti_min
= vr_p
->min
;
1353 anti_max
= vr_p
->max
;
1354 real_min
= var_vr
->min
;
1355 real_max
= var_vr
->max
;
1359 anti_min
= var_vr
->min
;
1360 anti_max
= var_vr
->max
;
1361 real_min
= vr_p
->min
;
1362 real_max
= vr_p
->max
;
1366 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1367 not including any endpoints. */
1368 if (compare_values (anti_max
, real_max
) == -1
1369 && compare_values (anti_min
, real_min
) == 1)
1371 set_value_range (vr_p
, VR_RANGE
, real_min
,
1372 real_max
, vr_p
->equiv
);
1374 /* Case 2, VR_ANTI_RANGE completely disjoint from
1376 else if (compare_values (anti_min
, real_max
) == 1
1377 || compare_values (anti_max
, real_min
) == -1)
1379 set_value_range (vr_p
, VR_RANGE
, real_min
,
1380 real_max
, vr_p
->equiv
);
1382 /* Case 3a, the anti-range extends into the low
1383 part of the real range. Thus creating a new
1384 low for the real range. */
1385 else if (((cmp
= compare_values (anti_max
, real_min
)) == 1
1387 && compare_values (anti_max
, real_max
) == -1)
1389 gcc_assert (!is_positive_overflow_infinity (anti_max
));
1390 if (needs_overflow_infinity (TREE_TYPE (anti_max
))
1391 && anti_max
== TYPE_MAX_VALUE (TREE_TYPE (anti_max
)))
1393 if (!supports_overflow_infinity (TREE_TYPE (var_vr
->min
)))
1395 set_value_range_to_varying (vr_p
);
1398 min
= positive_overflow_infinity (TREE_TYPE (var_vr
->min
));
1401 min
= fold_build2 (PLUS_EXPR
, TREE_TYPE (var_vr
->min
),
1403 build_int_cst (TREE_TYPE (var_vr
->min
), 1));
1405 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1407 /* Case 3b, the anti-range extends into the high
1408 part of the real range. Thus creating a new
1409 higher for the real range. */
1410 else if (compare_values (anti_min
, real_min
) == 1
1411 && ((cmp
= compare_values (anti_min
, real_max
)) == -1
1414 gcc_assert (!is_negative_overflow_infinity (anti_min
));
1415 if (needs_overflow_infinity (TREE_TYPE (anti_min
))
1416 && anti_min
== TYPE_MIN_VALUE (TREE_TYPE (anti_min
)))
1418 if (!supports_overflow_infinity (TREE_TYPE (var_vr
->min
)))
1420 set_value_range_to_varying (vr_p
);
1423 max
= negative_overflow_infinity (TREE_TYPE (var_vr
->min
));
1426 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (var_vr
->min
),
1428 build_int_cst (TREE_TYPE (var_vr
->min
), 1));
1430 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1437 /* Extract range information from SSA name VAR and store it in VR. If
1438 VAR has an interesting range, use it. Otherwise, create the
1439 range [VAR, VAR] and return it. This is useful in situations where
1440 we may have conditionals testing values of VARYING names. For
1447 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1451 extract_range_from_ssa_name (value_range_t
*vr
, tree var
)
1453 value_range_t
*var_vr
= get_value_range (var
);
1455 if (var_vr
->type
!= VR_UNDEFINED
&& var_vr
->type
!= VR_VARYING
)
1456 copy_value_range (vr
, var_vr
);
1458 set_value_range (vr
, VR_RANGE
, var
, var
, NULL
);
1460 add_equivalence (vr
->equiv
, var
);
1464 /* Wrapper around int_const_binop. If the operation overflows and we
1465 are not using wrapping arithmetic, then adjust the result to be
1466 -INF or +INF depending on CODE, VAL1 and VAL2. This can return
1467 NULL_TREE if we need to use an overflow infinity representation but
1468 the type does not support it. */
1471 vrp_int_const_binop (enum tree_code code
, tree val1
, tree val2
)
1475 res
= int_const_binop (code
, val1
, val2
, 0);
1477 /* If we are not using wrapping arithmetic, operate symbolically
1478 on -INF and +INF. */
1479 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1
)))
1481 int checkz
= compare_values (res
, val1
);
1482 bool overflow
= false;
1484 /* Ensure that res = val1 [+*] val2 >= val1
1485 or that res = val1 - val2 <= val1. */
1486 if ((code
== PLUS_EXPR
1487 && !(checkz
== 1 || checkz
== 0))
1488 || (code
== MINUS_EXPR
1489 && !(checkz
== 0 || checkz
== -1)))
1493 /* Checking for multiplication overflow is done by dividing the
1494 output of the multiplication by the first input of the
1495 multiplication. If the result of that division operation is
1496 not equal to the second input of the multiplication, then the
1497 multiplication overflowed. */
1498 else if (code
== MULT_EXPR
&& !integer_zerop (val1
))
1500 tree tmp
= int_const_binop (TRUNC_DIV_EXPR
,
1503 int check
= compare_values (tmp
, val2
);
1511 res
= copy_node (res
);
1512 TREE_OVERFLOW (res
) = 1;
1516 else if ((TREE_OVERFLOW (res
)
1517 && !TREE_OVERFLOW (val1
)
1518 && !TREE_OVERFLOW (val2
))
1519 || is_overflow_infinity (val1
)
1520 || is_overflow_infinity (val2
))
1522 /* If the operation overflowed but neither VAL1 nor VAL2 are
1523 overflown, return -INF or +INF depending on the operation
1524 and the combination of signs of the operands. */
1525 int sgn1
= tree_int_cst_sgn (val1
);
1526 int sgn2
= tree_int_cst_sgn (val2
);
1528 if (needs_overflow_infinity (TREE_TYPE (res
))
1529 && !supports_overflow_infinity (TREE_TYPE (res
)))
1532 /* We have to punt on adding infinities of different signs,
1533 since we can't tell what the sign of the result should be.
1534 Likewise for subtracting infinities of the same sign. */
1535 if (((code
== PLUS_EXPR
&& sgn1
!= sgn2
)
1536 || (code
== MINUS_EXPR
&& sgn1
== sgn2
))
1537 && is_overflow_infinity (val1
)
1538 && is_overflow_infinity (val2
))
1541 /* Don't try to handle division or shifting of infinities. */
1542 if ((code
== TRUNC_DIV_EXPR
1543 || code
== FLOOR_DIV_EXPR
1544 || code
== CEIL_DIV_EXPR
1545 || code
== EXACT_DIV_EXPR
1546 || code
== ROUND_DIV_EXPR
1547 || code
== RSHIFT_EXPR
)
1548 && (is_overflow_infinity (val1
)
1549 || is_overflow_infinity (val2
)))
1552 /* Notice that we only need to handle the restricted set of
1553 operations handled by extract_range_from_binary_expr.
1554 Among them, only multiplication, addition and subtraction
1555 can yield overflow without overflown operands because we
1556 are working with integral types only... except in the
1557 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1558 for division too. */
1560 /* For multiplication, the sign of the overflow is given
1561 by the comparison of the signs of the operands. */
1562 if ((code
== MULT_EXPR
&& sgn1
== sgn2
)
1563 /* For addition, the operands must be of the same sign
1564 to yield an overflow. Its sign is therefore that
1565 of one of the operands, for example the first. For
1566 infinite operands X + -INF is negative, not positive. */
1567 || (code
== PLUS_EXPR
1569 ? !is_negative_overflow_infinity (val2
)
1570 : is_positive_overflow_infinity (val2
)))
1571 /* For subtraction, non-infinite operands must be of
1572 different signs to yield an overflow. Its sign is
1573 therefore that of the first operand or the opposite of
1574 that of the second operand. A first operand of 0 counts
1575 as positive here, for the corner case 0 - (-INF), which
1576 overflows, but must yield +INF. For infinite operands 0
1577 - INF is negative, not positive. */
1578 || (code
== MINUS_EXPR
1580 ? !is_positive_overflow_infinity (val2
)
1581 : is_negative_overflow_infinity (val2
)))
1582 /* We only get in here with positive shift count, so the
1583 overflow direction is the same as the sign of val1.
1584 Actually rshift does not overflow at all, but we only
1585 handle the case of shifting overflowed -INF and +INF. */
1586 || (code
== RSHIFT_EXPR
1588 /* For division, the only case is -INF / -1 = +INF. */
1589 || code
== TRUNC_DIV_EXPR
1590 || code
== FLOOR_DIV_EXPR
1591 || code
== CEIL_DIV_EXPR
1592 || code
== EXACT_DIV_EXPR
1593 || code
== ROUND_DIV_EXPR
)
1594 return (needs_overflow_infinity (TREE_TYPE (res
))
1595 ? positive_overflow_infinity (TREE_TYPE (res
))
1596 : TYPE_MAX_VALUE (TREE_TYPE (res
)));
1598 return (needs_overflow_infinity (TREE_TYPE (res
))
1599 ? negative_overflow_infinity (TREE_TYPE (res
))
1600 : TYPE_MIN_VALUE (TREE_TYPE (res
)));
1607 /* Extract range information from a binary expression EXPR based on
1608 the ranges of each of its operands and the expression code. */
1611 extract_range_from_binary_expr (value_range_t
*vr
, tree expr
)
1613 enum tree_code code
= TREE_CODE (expr
);
1614 enum value_range_type type
;
1615 tree op0
, op1
, min
, max
;
1617 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1618 value_range_t vr1
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1620 /* Not all binary expressions can be applied to ranges in a
1621 meaningful way. Handle only arithmetic operations. */
1622 if (code
!= PLUS_EXPR
1623 && code
!= MINUS_EXPR
1624 && code
!= MULT_EXPR
1625 && code
!= TRUNC_DIV_EXPR
1626 && code
!= FLOOR_DIV_EXPR
1627 && code
!= CEIL_DIV_EXPR
1628 && code
!= EXACT_DIV_EXPR
1629 && code
!= ROUND_DIV_EXPR
1630 && code
!= RSHIFT_EXPR
1633 && code
!= BIT_AND_EXPR
1634 && code
!= TRUTH_ANDIF_EXPR
1635 && code
!= TRUTH_ORIF_EXPR
1636 && code
!= TRUTH_AND_EXPR
1637 && code
!= TRUTH_OR_EXPR
)
1639 set_value_range_to_varying (vr
);
1643 /* Get value ranges for each operand. For constant operands, create
1644 a new value range with the operand to simplify processing. */
1645 op0
= TREE_OPERAND (expr
, 0);
1646 if (TREE_CODE (op0
) == SSA_NAME
)
1647 vr0
= *(get_value_range (op0
));
1648 else if (is_gimple_min_invariant (op0
))
1649 set_value_range (&vr0
, VR_RANGE
, op0
, op0
, NULL
);
1651 set_value_range_to_varying (&vr0
);
1653 op1
= TREE_OPERAND (expr
, 1);
1654 if (TREE_CODE (op1
) == SSA_NAME
)
1655 vr1
= *(get_value_range (op1
));
1656 else if (is_gimple_min_invariant (op1
))
1657 set_value_range (&vr1
, VR_RANGE
, op1
, op1
, NULL
);
1659 set_value_range_to_varying (&vr1
);
1661 /* If either range is UNDEFINED, so is the result. */
1662 if (vr0
.type
== VR_UNDEFINED
|| vr1
.type
== VR_UNDEFINED
)
1664 set_value_range_to_undefined (vr
);
1668 /* The type of the resulting value range defaults to VR0.TYPE. */
1671 /* Refuse to operate on VARYING ranges, ranges of different kinds
1672 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1673 because we may be able to derive a useful range even if one of
1674 the operands is VR_VARYING or symbolic range. TODO, we may be
1675 able to derive anti-ranges in some cases. */
1676 if (code
!= BIT_AND_EXPR
1677 && code
!= TRUTH_AND_EXPR
1678 && code
!= TRUTH_OR_EXPR
1679 && (vr0
.type
== VR_VARYING
1680 || vr1
.type
== VR_VARYING
1681 || vr0
.type
!= vr1
.type
1682 || symbolic_range_p (&vr0
)
1683 || symbolic_range_p (&vr1
)))
1685 set_value_range_to_varying (vr
);
1689 /* Now evaluate the expression to determine the new range. */
1690 if (POINTER_TYPE_P (TREE_TYPE (expr
))
1691 || POINTER_TYPE_P (TREE_TYPE (op0
))
1692 || POINTER_TYPE_P (TREE_TYPE (op1
)))
1694 /* For pointer types, we are really only interested in asserting
1695 whether the expression evaluates to non-NULL. FIXME, we used
1696 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1697 ivopts is generating expressions with pointer multiplication
1699 if (code
== PLUS_EXPR
)
1701 if (range_is_nonnull (&vr0
) || range_is_nonnull (&vr1
))
1702 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1703 else if (range_is_null (&vr0
) && range_is_null (&vr1
))
1704 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1706 set_value_range_to_varying (vr
);
1710 /* Subtracting from a pointer, may yield 0, so just drop the
1711 resulting range to varying. */
1712 set_value_range_to_varying (vr
);
1718 /* For integer ranges, apply the operation to each end of the
1719 range and see what we end up with. */
1720 if (code
== TRUTH_ANDIF_EXPR
1721 || code
== TRUTH_ORIF_EXPR
1722 || code
== TRUTH_AND_EXPR
1723 || code
== TRUTH_OR_EXPR
)
1725 /* If one of the operands is zero, we know that the whole
1726 expression evaluates zero. */
1727 if (code
== TRUTH_AND_EXPR
1728 && ((vr0
.type
== VR_RANGE
1729 && integer_zerop (vr0
.min
)
1730 && integer_zerop (vr0
.max
))
1731 || (vr1
.type
== VR_RANGE
1732 && integer_zerop (vr1
.min
)
1733 && integer_zerop (vr1
.max
))))
1736 min
= max
= build_int_cst (TREE_TYPE (expr
), 0);
1738 /* If one of the operands is one, we know that the whole
1739 expression evaluates one. */
1740 else if (code
== TRUTH_OR_EXPR
1741 && ((vr0
.type
== VR_RANGE
1742 && integer_onep (vr0
.min
)
1743 && integer_onep (vr0
.max
))
1744 || (vr1
.type
== VR_RANGE
1745 && integer_onep (vr1
.min
)
1746 && integer_onep (vr1
.max
))))
1749 min
= max
= build_int_cst (TREE_TYPE (expr
), 1);
1751 else if (vr0
.type
!= VR_VARYING
1752 && vr1
.type
!= VR_VARYING
1753 && vr0
.type
== vr1
.type
1754 && !symbolic_range_p (&vr0
)
1755 && !overflow_infinity_range_p (&vr0
)
1756 && !symbolic_range_p (&vr1
)
1757 && !overflow_infinity_range_p (&vr1
))
1759 /* Boolean expressions cannot be folded with int_const_binop. */
1760 min
= fold_binary (code
, TREE_TYPE (expr
), vr0
.min
, vr1
.min
);
1761 max
= fold_binary (code
, TREE_TYPE (expr
), vr0
.max
, vr1
.max
);
1765 /* The result of a TRUTH_*_EXPR is always true or false. */
1766 set_value_range_to_truthvalue (vr
, TREE_TYPE (expr
));
1770 else if (code
== PLUS_EXPR
1772 || code
== MAX_EXPR
)
1774 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1775 VR_VARYING. It would take more effort to compute a precise
1776 range for such a case. For example, if we have op0 == 1 and
1777 op1 == -1 with their ranges both being ~[0,0], we would have
1778 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1779 Note that we are guaranteed to have vr0.type == vr1.type at
1781 if (code
== PLUS_EXPR
&& vr0
.type
== VR_ANTI_RANGE
)
1783 set_value_range_to_varying (vr
);
1787 /* For operations that make the resulting range directly
1788 proportional to the original ranges, apply the operation to
1789 the same end of each range. */
1790 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1791 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.max
);
1793 else if (code
== MULT_EXPR
1794 || code
== TRUNC_DIV_EXPR
1795 || code
== FLOOR_DIV_EXPR
1796 || code
== CEIL_DIV_EXPR
1797 || code
== EXACT_DIV_EXPR
1798 || code
== ROUND_DIV_EXPR
1799 || code
== RSHIFT_EXPR
)
1805 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1806 drop to VR_VARYING. It would take more effort to compute a
1807 precise range for such a case. For example, if we have
1808 op0 == 65536 and op1 == 65536 with their ranges both being
1809 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1810 we cannot claim that the product is in ~[0,0]. Note that we
1811 are guaranteed to have vr0.type == vr1.type at this
1813 if (code
== MULT_EXPR
1814 && vr0
.type
== VR_ANTI_RANGE
1815 && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0
)))
1817 set_value_range_to_varying (vr
);
1821 /* If we have a RSHIFT_EXPR with any shift values outside [0..prec-1],
1822 then drop to VR_VARYING. Outside of this range we get undefined
1823 behavior from the shift operation. We cannot even trust
1824 SHIFT_COUNT_TRUNCATED at this stage, because that applies to rtl
1825 shifts, and the operation at the tree level may be widened. */
1826 if (code
== RSHIFT_EXPR
)
1828 if (vr1
.type
== VR_ANTI_RANGE
1829 || !vrp_expr_computes_nonnegative (op1
, &sop
)
1831 (build_int_cst (TREE_TYPE (vr1
.max
),
1832 TYPE_PRECISION (TREE_TYPE (expr
)) - 1),
1835 set_value_range_to_varying (vr
);
1840 /* Multiplications and divisions are a bit tricky to handle,
1841 depending on the mix of signs we have in the two ranges, we
1842 need to operate on different values to get the minimum and
1843 maximum values for the new range. One approach is to figure
1844 out all the variations of range combinations and do the
1847 However, this involves several calls to compare_values and it
1848 is pretty convoluted. It's simpler to do the 4 operations
1849 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1850 MAX1) and then figure the smallest and largest values to form
1853 /* Divisions by zero result in a VARYING value. */
1854 else if (code
!= MULT_EXPR
1855 && (vr0
.type
== VR_ANTI_RANGE
|| range_includes_zero_p (&vr1
)))
1857 set_value_range_to_varying (vr
);
1861 /* Compute the 4 cross operations. */
1863 val
[0] = vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1864 if (val
[0] == NULL_TREE
)
1867 if (vr1
.max
== vr1
.min
)
1871 val
[1] = vrp_int_const_binop (code
, vr0
.min
, vr1
.max
);
1872 if (val
[1] == NULL_TREE
)
1876 if (vr0
.max
== vr0
.min
)
1880 val
[2] = vrp_int_const_binop (code
, vr0
.max
, vr1
.min
);
1881 if (val
[2] == NULL_TREE
)
1885 if (vr0
.min
== vr0
.max
|| vr1
.min
== vr1
.max
)
1889 val
[3] = vrp_int_const_binop (code
, vr0
.max
, vr1
.max
);
1890 if (val
[3] == NULL_TREE
)
1896 set_value_range_to_varying (vr
);
1900 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1904 for (i
= 1; i
< 4; i
++)
1906 if (!is_gimple_min_invariant (min
)
1907 || (TREE_OVERFLOW (min
) && !is_overflow_infinity (min
))
1908 || !is_gimple_min_invariant (max
)
1909 || (TREE_OVERFLOW (max
) && !is_overflow_infinity (max
)))
1914 if (!is_gimple_min_invariant (val
[i
])
1915 || (TREE_OVERFLOW (val
[i
])
1916 && !is_overflow_infinity (val
[i
])))
1918 /* If we found an overflowed value, set MIN and MAX
1919 to it so that we set the resulting range to
1925 if (compare_values (val
[i
], min
) == -1)
1928 if (compare_values (val
[i
], max
) == 1)
1933 else if (code
== MINUS_EXPR
)
1935 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1936 VR_VARYING. It would take more effort to compute a precise
1937 range for such a case. For example, if we have op0 == 1 and
1938 op1 == 1 with their ranges both being ~[0,0], we would have
1939 op0 - op1 == 0, so we cannot claim that the difference is in
1940 ~[0,0]. Note that we are guaranteed to have
1941 vr0.type == vr1.type at this point. */
1942 if (vr0
.type
== VR_ANTI_RANGE
)
1944 set_value_range_to_varying (vr
);
1948 /* For MINUS_EXPR, apply the operation to the opposite ends of
1950 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.max
);
1951 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.min
);
1953 else if (code
== BIT_AND_EXPR
)
1955 if (vr0
.type
== VR_RANGE
1956 && vr0
.min
== vr0
.max
1957 && TREE_CODE (vr0
.max
) == INTEGER_CST
1958 && !TREE_OVERFLOW (vr0
.max
)
1959 && tree_int_cst_sgn (vr0
.max
) >= 0)
1961 min
= build_int_cst (TREE_TYPE (expr
), 0);
1964 else if (vr1
.type
== VR_RANGE
1965 && vr1
.min
== vr1
.max
1966 && TREE_CODE (vr1
.max
) == INTEGER_CST
1967 && !TREE_OVERFLOW (vr1
.max
)
1968 && tree_int_cst_sgn (vr1
.max
) >= 0)
1971 min
= build_int_cst (TREE_TYPE (expr
), 0);
1976 set_value_range_to_varying (vr
);
1983 /* If either MIN or MAX overflowed, then set the resulting range to
1984 VARYING. But we do accept an overflow infinity
1986 if (min
== NULL_TREE
1987 || !is_gimple_min_invariant (min
)
1988 || (TREE_OVERFLOW (min
) && !is_overflow_infinity (min
))
1990 || !is_gimple_min_invariant (max
)
1991 || (TREE_OVERFLOW (max
) && !is_overflow_infinity (max
)))
1993 set_value_range_to_varying (vr
);
1999 2) [-INF, +-INF(OVF)]
2000 3) [+-INF(OVF), +INF]
2001 4) [+-INF(OVF), +-INF(OVF)]
2002 We learn nothing when we have INF and INF(OVF) on both sides.
2003 Note that we do accept [-INF, -INF] and [+INF, +INF] without
2005 if ((min
== TYPE_MIN_VALUE (TREE_TYPE (min
))
2006 || is_overflow_infinity (min
))
2007 && (max
== TYPE_MAX_VALUE (TREE_TYPE (max
))
2008 || is_overflow_infinity (max
)))
2010 set_value_range_to_varying (vr
);
2014 cmp
= compare_values (min
, max
);
2015 if (cmp
== -2 || cmp
== 1)
2017 /* If the new range has its limits swapped around (MIN > MAX),
2018 then the operation caused one of them to wrap around, mark
2019 the new range VARYING. */
2020 set_value_range_to_varying (vr
);
2023 set_value_range (vr
, type
, min
, max
, NULL
);
2027 /* Extract range information from a unary expression EXPR based on
2028 the range of its operand and the expression code. */
2031 extract_range_from_unary_expr (value_range_t
*vr
, tree expr
)
2033 enum tree_code code
= TREE_CODE (expr
);
2036 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
2038 /* Refuse to operate on certain unary expressions for which we
2039 cannot easily determine a resulting range. */
2040 if (code
== FIX_TRUNC_EXPR
2041 || code
== FLOAT_EXPR
2042 || code
== BIT_NOT_EXPR
2043 || code
== NON_LVALUE_EXPR
2044 || code
== CONJ_EXPR
)
2046 set_value_range_to_varying (vr
);
2050 /* Get value ranges for the operand. For constant operands, create
2051 a new value range with the operand to simplify processing. */
2052 op0
= TREE_OPERAND (expr
, 0);
2053 if (TREE_CODE (op0
) == SSA_NAME
)
2054 vr0
= *(get_value_range (op0
));
2055 else if (is_gimple_min_invariant (op0
))
2056 set_value_range (&vr0
, VR_RANGE
, op0
, op0
, NULL
);
2058 set_value_range_to_varying (&vr0
);
2060 /* If VR0 is UNDEFINED, so is the result. */
2061 if (vr0
.type
== VR_UNDEFINED
)
2063 set_value_range_to_undefined (vr
);
2067 /* Refuse to operate on symbolic ranges, or if neither operand is
2068 a pointer or integral type. */
2069 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
2070 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
2071 || (vr0
.type
!= VR_VARYING
2072 && symbolic_range_p (&vr0
)))
2074 set_value_range_to_varying (vr
);
2078 /* If the expression involves pointers, we are only interested in
2079 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
2080 if (POINTER_TYPE_P (TREE_TYPE (expr
)) || POINTER_TYPE_P (TREE_TYPE (op0
)))
2085 if (range_is_nonnull (&vr0
)
2086 || (tree_expr_nonzero_warnv_p (expr
, &sop
)
2088 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
2089 else if (range_is_null (&vr0
))
2090 set_value_range_to_null (vr
, TREE_TYPE (expr
));
2092 set_value_range_to_varying (vr
);
2097 /* Handle unary expressions on integer ranges. */
2098 if (code
== NOP_EXPR
|| code
== CONVERT_EXPR
)
2100 tree inner_type
= TREE_TYPE (op0
);
2101 tree outer_type
= TREE_TYPE (expr
);
2103 /* If VR0 represents a simple range, then try to convert
2104 the min and max values for the range to the same type
2105 as OUTER_TYPE. If the results compare equal to VR0's
2106 min and max values and the new min is still less than
2107 or equal to the new max, then we can safely use the newly
2108 computed range for EXPR. This allows us to compute
2109 accurate ranges through many casts. */
2110 if ((vr0
.type
== VR_RANGE
2111 && !overflow_infinity_range_p (&vr0
))
2112 || (vr0
.type
== VR_VARYING
2113 && TYPE_PRECISION (outer_type
) > TYPE_PRECISION (inner_type
)))
2115 tree new_min
, new_max
, orig_min
, orig_max
;
2117 /* Convert the input operand min/max to OUTER_TYPE. If
2118 the input has no range information, then use the min/max
2119 for the input's type. */
2120 if (vr0
.type
== VR_RANGE
)
2127 orig_min
= TYPE_MIN_VALUE (inner_type
);
2128 orig_max
= TYPE_MAX_VALUE (inner_type
);
2131 new_min
= fold_convert (outer_type
, orig_min
);
2132 new_max
= fold_convert (outer_type
, orig_max
);
2134 /* Verify the new min/max values are gimple values and
2135 that they compare equal to the original input's
2137 if (is_gimple_val (new_min
)
2138 && is_gimple_val (new_max
)
2139 && tree_int_cst_equal (new_min
, orig_min
)
2140 && tree_int_cst_equal (new_max
, orig_max
)
2141 && (cmp
= compare_values (new_min
, new_max
)) <= 0
2144 set_value_range (vr
, VR_RANGE
, new_min
, new_max
, vr
->equiv
);
2149 /* When converting types of different sizes, set the result to
2150 VARYING. Things like sign extensions and precision loss may
2151 change the range. For instance, if x_3 is of type 'long long
2152 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
2153 is impossible to know at compile time whether y_5 will be
2155 if (TYPE_SIZE (inner_type
) != TYPE_SIZE (outer_type
)
2156 || TYPE_PRECISION (inner_type
) != TYPE_PRECISION (outer_type
))
2158 set_value_range_to_varying (vr
);
2163 /* Conversion of a VR_VARYING value to a wider type can result
2164 in a usable range. So wait until after we've handled conversions
2165 before dropping the result to VR_VARYING if we had a source
2166 operand that is VR_VARYING. */
2167 if (vr0
.type
== VR_VARYING
)
2169 set_value_range_to_varying (vr
);
2173 /* Apply the operation to each end of the range and see what we end
2175 if (code
== NEGATE_EXPR
2176 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
2178 /* NEGATE_EXPR flips the range around. We need to treat
2179 TYPE_MIN_VALUE specially. */
2180 if (is_positive_overflow_infinity (vr0
.max
))
2181 min
= negative_overflow_infinity (TREE_TYPE (expr
));
2182 else if (is_negative_overflow_infinity (vr0
.max
))
2183 min
= positive_overflow_infinity (TREE_TYPE (expr
));
2184 else if (vr0
.max
!= TYPE_MIN_VALUE (TREE_TYPE (expr
)))
2185 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
2186 else if (needs_overflow_infinity (TREE_TYPE (expr
)))
2188 if (supports_overflow_infinity (TREE_TYPE (expr
)))
2189 min
= positive_overflow_infinity (TREE_TYPE (expr
));
2192 set_value_range_to_varying (vr
);
2197 min
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
2199 if (is_positive_overflow_infinity (vr0
.min
))
2200 max
= negative_overflow_infinity (TREE_TYPE (expr
));
2201 else if (is_negative_overflow_infinity (vr0
.min
))
2202 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2203 else if (vr0
.min
!= TYPE_MIN_VALUE (TREE_TYPE (expr
)))
2204 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
2205 else if (needs_overflow_infinity (TREE_TYPE (expr
)))
2207 if (supports_overflow_infinity (TREE_TYPE (expr
)))
2208 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2211 set_value_range_to_varying (vr
);
2216 max
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
2218 else if (code
== NEGATE_EXPR
2219 && TYPE_UNSIGNED (TREE_TYPE (expr
)))
2221 if (!range_includes_zero_p (&vr0
))
2223 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
2224 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
2228 if (range_is_null (&vr0
))
2229 set_value_range_to_null (vr
, TREE_TYPE (expr
));
2231 set_value_range_to_varying (vr
);
2235 else if (code
== ABS_EXPR
2236 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
2238 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
2240 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (expr
))
2241 && ((vr0
.type
== VR_RANGE
2242 && vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
)))
2243 || (vr0
.type
== VR_ANTI_RANGE
2244 && vr0
.min
!= TYPE_MIN_VALUE (TREE_TYPE (expr
))
2245 && !range_includes_zero_p (&vr0
))))
2247 set_value_range_to_varying (vr
);
2251 /* ABS_EXPR may flip the range around, if the original range
2252 included negative values. */
2253 if (is_overflow_infinity (vr0
.min
))
2254 min
= positive_overflow_infinity (TREE_TYPE (expr
));
2255 else if (vr0
.min
!= TYPE_MIN_VALUE (TREE_TYPE (expr
)))
2256 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
2257 else if (!needs_overflow_infinity (TREE_TYPE (expr
)))
2258 min
= TYPE_MAX_VALUE (TREE_TYPE (expr
));
2259 else if (supports_overflow_infinity (TREE_TYPE (expr
)))
2260 min
= positive_overflow_infinity (TREE_TYPE (expr
));
2263 set_value_range_to_varying (vr
);
2267 if (is_overflow_infinity (vr0
.max
))
2268 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2269 else if (vr0
.max
!= TYPE_MIN_VALUE (TREE_TYPE (expr
)))
2270 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
2271 else if (!needs_overflow_infinity (TREE_TYPE (expr
)))
2272 max
= TYPE_MAX_VALUE (TREE_TYPE (expr
));
2273 else if (supports_overflow_infinity (TREE_TYPE (expr
)))
2274 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2277 set_value_range_to_varying (vr
);
2281 cmp
= compare_values (min
, max
);
2283 /* If a VR_ANTI_RANGEs contains zero, then we have
2284 ~[-INF, min(MIN, MAX)]. */
2285 if (vr0
.type
== VR_ANTI_RANGE
)
2287 if (range_includes_zero_p (&vr0
))
2289 /* Take the lower of the two values. */
2293 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
2294 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
2295 flag_wrapv is set and the original anti-range doesn't include
2296 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
2297 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr
)))
2299 tree type_min_value
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
2301 min
= (vr0
.min
!= type_min_value
2302 ? int_const_binop (PLUS_EXPR
, type_min_value
,
2303 integer_one_node
, 0)
2308 if (overflow_infinity_range_p (&vr0
))
2309 min
= negative_overflow_infinity (TREE_TYPE (expr
));
2311 min
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
2316 /* All else has failed, so create the range [0, INF], even for
2317 flag_wrapv since TYPE_MIN_VALUE is in the original
2319 vr0
.type
= VR_RANGE
;
2320 min
= build_int_cst (TREE_TYPE (expr
), 0);
2321 if (needs_overflow_infinity (TREE_TYPE (expr
)))
2323 if (supports_overflow_infinity (TREE_TYPE (expr
)))
2324 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2327 set_value_range_to_varying (vr
);
2332 max
= TYPE_MAX_VALUE (TREE_TYPE (expr
));
2336 /* If the range contains zero then we know that the minimum value in the
2337 range will be zero. */
2338 else if (range_includes_zero_p (&vr0
))
2342 min
= build_int_cst (TREE_TYPE (expr
), 0);
2346 /* If the range was reversed, swap MIN and MAX. */
2357 /* Otherwise, operate on each end of the range. */
2358 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
2359 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
2361 if (needs_overflow_infinity (TREE_TYPE (expr
)))
2363 gcc_assert (code
!= NEGATE_EXPR
&& code
!= ABS_EXPR
);
2364 if (is_overflow_infinity (vr0
.min
))
2366 else if (TREE_OVERFLOW (min
))
2368 if (supports_overflow_infinity (TREE_TYPE (expr
)))
2369 min
= (tree_int_cst_sgn (min
) >= 0
2370 ? positive_overflow_infinity (TREE_TYPE (min
))
2371 : negative_overflow_infinity (TREE_TYPE (min
)));
2374 set_value_range_to_varying (vr
);
2379 if (is_overflow_infinity (vr0
.max
))
2381 else if (TREE_OVERFLOW (max
))
2383 if (supports_overflow_infinity (TREE_TYPE (expr
)))
2384 max
= (tree_int_cst_sgn (max
) >= 0
2385 ? positive_overflow_infinity (TREE_TYPE (max
))
2386 : negative_overflow_infinity (TREE_TYPE (max
)));
2389 set_value_range_to_varying (vr
);
2396 cmp
= compare_values (min
, max
);
2397 if (cmp
== -2 || cmp
== 1)
2399 /* If the new range has its limits swapped around (MIN > MAX),
2400 then the operation caused one of them to wrap around, mark
2401 the new range VARYING. */
2402 set_value_range_to_varying (vr
);
2405 set_value_range (vr
, vr0
.type
, min
, max
, NULL
);
2409 /* Extract range information from a conditional expression EXPR based on
2410 the ranges of each of its operands and the expression code. */
2413 extract_range_from_cond_expr (value_range_t
*vr
, tree expr
)
2416 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
2417 value_range_t vr1
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
2419 /* Get value ranges for each operand. For constant operands, create
2420 a new value range with the operand to simplify processing. */
2421 op0
= COND_EXPR_THEN (expr
);
2422 if (TREE_CODE (op0
) == SSA_NAME
)
2423 vr0
= *(get_value_range (op0
));
2424 else if (is_gimple_min_invariant (op0
))
2425 set_value_range (&vr0
, VR_RANGE
, op0
, op0
, NULL
);
2427 set_value_range_to_varying (&vr0
);
2429 op1
= COND_EXPR_ELSE (expr
);
2430 if (TREE_CODE (op1
) == SSA_NAME
)
2431 vr1
= *(get_value_range (op1
));
2432 else if (is_gimple_min_invariant (op1
))
2433 set_value_range (&vr1
, VR_RANGE
, op1
, op1
, NULL
);
2435 set_value_range_to_varying (&vr1
);
2437 /* The resulting value range is the union of the operand ranges */
2438 vrp_meet (&vr0
, &vr1
);
2439 copy_value_range (vr
, &vr0
);
2443 /* Extract range information from a comparison expression EXPR based
2444 on the range of its operand and the expression code. */
2447 extract_range_from_comparison (value_range_t
*vr
, tree expr
)
2450 tree val
= vrp_evaluate_conditional_warnv (expr
, false, &sop
);
2452 /* A disadvantage of using a special infinity as an overflow
2453 representation is that we lose the ability to record overflow
2454 when we don't have an infinity. So we have to ignore a result
2455 which relies on overflow. */
2457 if (val
&& !is_overflow_infinity (val
) && !sop
)
2459 /* Since this expression was found on the RHS of an assignment,
2460 its type may be different from _Bool. Convert VAL to EXPR's
2462 val
= fold_convert (TREE_TYPE (expr
), val
);
2463 set_value_range (vr
, VR_RANGE
, val
, val
, vr
->equiv
);
2466 /* The result of a comparison is always true or false. */
2467 set_value_range_to_truthvalue (vr
, TREE_TYPE (expr
));
2471 /* Try to compute a useful range out of expression EXPR and store it
2475 extract_range_from_expr (value_range_t
*vr
, tree expr
)
2477 enum tree_code code
= TREE_CODE (expr
);
2479 if (code
== ASSERT_EXPR
)
2480 extract_range_from_assert (vr
, expr
);
2481 else if (code
== SSA_NAME
)
2482 extract_range_from_ssa_name (vr
, expr
);
2483 else if (TREE_CODE_CLASS (code
) == tcc_binary
2484 || code
== TRUTH_ANDIF_EXPR
2485 || code
== TRUTH_ORIF_EXPR
2486 || code
== TRUTH_AND_EXPR
2487 || code
== TRUTH_OR_EXPR
2488 || code
== TRUTH_XOR_EXPR
)
2489 extract_range_from_binary_expr (vr
, expr
);
2490 else if (TREE_CODE_CLASS (code
) == tcc_unary
)
2491 extract_range_from_unary_expr (vr
, expr
);
2492 else if (code
== COND_EXPR
)
2493 extract_range_from_cond_expr (vr
, expr
);
2494 else if (TREE_CODE_CLASS (code
) == tcc_comparison
)
2495 extract_range_from_comparison (vr
, expr
);
2496 else if (is_gimple_min_invariant (expr
))
2497 set_value_range (vr
, VR_RANGE
, expr
, expr
, NULL
);
2499 set_value_range_to_varying (vr
);
2501 /* If we got a varying range from the tests above, try a final
2502 time to derive a nonnegative or nonzero range. This time
2503 relying primarily on generic routines in fold in conjunction
2505 if (vr
->type
== VR_VARYING
)
2509 if (INTEGRAL_TYPE_P (TREE_TYPE (expr
))
2510 && vrp_expr_computes_nonnegative (expr
, &sop
))
2511 set_value_range_to_nonnegative (vr
, TREE_TYPE (expr
),
2512 sop
|| is_overflow_infinity (expr
));
2513 else if (vrp_expr_computes_nonzero (expr
, &sop
)
2515 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
2519 /* Given a range VR, a LOOP and a variable VAR, determine whether it
2520 would be profitable to adjust VR using scalar evolution information
2521 for VAR. If so, update VR with the new limits. */
2524 adjust_range_with_scev (value_range_t
*vr
, struct loop
*loop
, tree stmt
,
2527 tree init
, step
, chrec
, tmin
, tmax
, min
, max
, type
;
2528 enum ev_direction dir
;
2530 /* TODO. Don't adjust anti-ranges. An anti-range may provide
2531 better opportunities than a regular range, but I'm not sure. */
2532 if (vr
->type
== VR_ANTI_RANGE
)
2535 chrec
= instantiate_parameters (loop
, analyze_scalar_evolution (loop
, var
));
2536 if (TREE_CODE (chrec
) != POLYNOMIAL_CHREC
)
2539 init
= initial_condition_in_loop_num (chrec
, loop
->num
);
2540 step
= evolution_part_in_loop_num (chrec
, loop
->num
);
2542 /* If STEP is symbolic, we can't know whether INIT will be the
2543 minimum or maximum value in the range. Also, unless INIT is
2544 a simple expression, compare_values and possibly other functions
2545 in tree-vrp won't be able to handle it. */
2546 if (step
== NULL_TREE
2547 || !is_gimple_min_invariant (step
)
2548 || !valid_value_p (init
))
2551 dir
= scev_direction (chrec
);
2552 if (/* Do not adjust ranges if we do not know whether the iv increases
2553 or decreases, ... */
2554 dir
== EV_DIR_UNKNOWN
2555 /* ... or if it may wrap. */
2556 || scev_probably_wraps_p (init
, step
, stmt
, get_chrec_loop (chrec
),
2560 /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of
2561 negative_overflow_infinity and positive_overflow_infinity,
2562 because we have concluded that the loop probably does not
2565 type
= TREE_TYPE (var
);
2566 if (POINTER_TYPE_P (type
) || !TYPE_MIN_VALUE (type
))
2567 tmin
= lower_bound_in_type (type
, type
);
2569 tmin
= TYPE_MIN_VALUE (type
);
2570 if (POINTER_TYPE_P (type
) || !TYPE_MAX_VALUE (type
))
2571 tmax
= upper_bound_in_type (type
, type
);
2573 tmax
= TYPE_MAX_VALUE (type
);
2575 if (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
)
2580 /* For VARYING or UNDEFINED ranges, just about anything we get
2581 from scalar evolutions should be better. */
2583 if (dir
== EV_DIR_DECREASES
)
2588 /* If we would create an invalid range, then just assume we
2589 know absolutely nothing. This may be over-conservative,
2590 but it's clearly safe, and should happen only in unreachable
2591 parts of code, or for invalid programs. */
2592 if (compare_values (min
, max
) == 1)
2595 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
2597 else if (vr
->type
== VR_RANGE
)
2602 if (dir
== EV_DIR_DECREASES
)
2604 /* INIT is the maximum value. If INIT is lower than VR->MAX
2605 but no smaller than VR->MIN, set VR->MAX to INIT. */
2606 if (compare_values (init
, max
) == -1)
2610 /* If we just created an invalid range with the minimum
2611 greater than the maximum, we fail conservatively.
2612 This should happen only in unreachable
2613 parts of code, or for invalid programs. */
2614 if (compare_values (min
, max
) == 1)
2620 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2621 if (compare_values (init
, min
) == 1)
2625 /* Again, avoid creating invalid range by failing. */
2626 if (compare_values (min
, max
) == 1)
2631 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
2636 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2638 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2639 all the values in the ranges.
2641 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2643 - Return NULL_TREE if it is not always possible to determine the
2644 value of the comparison.
2646 Also set *STRICT_OVERFLOW_P to indicate whether a range with an
2647 overflow infinity was used in the test. */
2651 compare_ranges (enum tree_code comp
, value_range_t
*vr0
, value_range_t
*vr1
,
2652 bool *strict_overflow_p
)
2654 /* VARYING or UNDEFINED ranges cannot be compared. */
2655 if (vr0
->type
== VR_VARYING
2656 || vr0
->type
== VR_UNDEFINED
2657 || vr1
->type
== VR_VARYING
2658 || vr1
->type
== VR_UNDEFINED
)
2661 /* Anti-ranges need to be handled separately. */
2662 if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
2664 /* If both are anti-ranges, then we cannot compute any
2666 if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
2669 /* These comparisons are never statically computable. */
2676 /* Equality can be computed only between a range and an
2677 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2678 if (vr0
->type
== VR_RANGE
)
2680 /* To simplify processing, make VR0 the anti-range. */
2681 value_range_t
*tmp
= vr0
;
2686 gcc_assert (comp
== NE_EXPR
|| comp
== EQ_EXPR
);
2688 if (compare_values_warnv (vr0
->min
, vr1
->min
, strict_overflow_p
) == 0
2689 && compare_values_warnv (vr0
->max
, vr1
->max
, strict_overflow_p
) == 0)
2690 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
2695 if (!usable_range_p (vr0
, strict_overflow_p
)
2696 || !usable_range_p (vr1
, strict_overflow_p
))
2699 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2700 operands around and change the comparison code. */
2701 if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
2704 comp
= (comp
== GT_EXPR
) ? LT_EXPR
: LE_EXPR
;
2710 if (comp
== EQ_EXPR
)
2712 /* Equality may only be computed if both ranges represent
2713 exactly one value. */
2714 if (compare_values_warnv (vr0
->min
, vr0
->max
, strict_overflow_p
) == 0
2715 && compare_values_warnv (vr1
->min
, vr1
->max
, strict_overflow_p
) == 0)
2717 int cmp_min
= compare_values_warnv (vr0
->min
, vr1
->min
,
2719 int cmp_max
= compare_values_warnv (vr0
->max
, vr1
->max
,
2721 if (cmp_min
== 0 && cmp_max
== 0)
2722 return boolean_true_node
;
2723 else if (cmp_min
!= -2 && cmp_max
!= -2)
2724 return boolean_false_node
;
2726 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2727 else if (compare_values_warnv (vr0
->min
, vr1
->max
,
2728 strict_overflow_p
) == 1
2729 || compare_values_warnv (vr1
->min
, vr0
->max
,
2730 strict_overflow_p
) == 1)
2731 return boolean_false_node
;
2735 else if (comp
== NE_EXPR
)
2739 /* If VR0 is completely to the left or completely to the right
2740 of VR1, they are always different. Notice that we need to
2741 make sure that both comparisons yield similar results to
2742 avoid comparing values that cannot be compared at
2744 cmp1
= compare_values_warnv (vr0
->max
, vr1
->min
, strict_overflow_p
);
2745 cmp2
= compare_values_warnv (vr0
->min
, vr1
->max
, strict_overflow_p
);
2746 if ((cmp1
== -1 && cmp2
== -1) || (cmp1
== 1 && cmp2
== 1))
2747 return boolean_true_node
;
2749 /* If VR0 and VR1 represent a single value and are identical,
2751 else if (compare_values_warnv (vr0
->min
, vr0
->max
,
2752 strict_overflow_p
) == 0
2753 && compare_values_warnv (vr1
->min
, vr1
->max
,
2754 strict_overflow_p
) == 0
2755 && compare_values_warnv (vr0
->min
, vr1
->min
,
2756 strict_overflow_p
) == 0
2757 && compare_values_warnv (vr0
->max
, vr1
->max
,
2758 strict_overflow_p
) == 0)
2759 return boolean_false_node
;
2761 /* Otherwise, they may or may not be different. */
2765 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
2769 /* If VR0 is to the left of VR1, return true. */
2770 tst
= compare_values_warnv (vr0
->max
, vr1
->min
, strict_overflow_p
);
2771 if ((comp
== LT_EXPR
&& tst
== -1)
2772 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
2774 if (overflow_infinity_range_p (vr0
)
2775 || overflow_infinity_range_p (vr1
))
2776 *strict_overflow_p
= true;
2777 return boolean_true_node
;
2780 /* If VR0 is to the right of VR1, return false. */
2781 tst
= compare_values_warnv (vr0
->min
, vr1
->max
, strict_overflow_p
);
2782 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
2783 || (comp
== LE_EXPR
&& tst
== 1))
2785 if (overflow_infinity_range_p (vr0
)
2786 || overflow_infinity_range_p (vr1
))
2787 *strict_overflow_p
= true;
2788 return boolean_false_node
;
2791 /* Otherwise, we don't know. */
2799 /* Given a value range VR, a value VAL and a comparison code COMP, return
2800 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2801 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2802 always returns false. Return NULL_TREE if it is not always
2803 possible to determine the value of the comparison. Also set
2804 *STRICT_OVERFLOW_P to indicate whether a range with an overflow
2805 infinity was used in the test. */
2808 compare_range_with_value (enum tree_code comp
, value_range_t
*vr
, tree val
,
2809 bool *strict_overflow_p
)
2811 if (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
)
2814 /* Anti-ranges need to be handled separately. */
2815 if (vr
->type
== VR_ANTI_RANGE
)
2817 /* For anti-ranges, the only predicates that we can compute at
2818 compile time are equality and inequality. */
2825 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2826 if (value_inside_range (val
, vr
) == 1)
2827 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
2832 if (!usable_range_p (vr
, strict_overflow_p
))
2835 if (comp
== EQ_EXPR
)
2837 /* EQ_EXPR may only be computed if VR represents exactly
2839 if (compare_values_warnv (vr
->min
, vr
->max
, strict_overflow_p
) == 0)
2841 int cmp
= compare_values_warnv (vr
->min
, val
, strict_overflow_p
);
2843 return boolean_true_node
;
2844 else if (cmp
== -1 || cmp
== 1 || cmp
== 2)
2845 return boolean_false_node
;
2847 else if (compare_values_warnv (val
, vr
->min
, strict_overflow_p
) == -1
2848 || compare_values_warnv (vr
->max
, val
, strict_overflow_p
) == -1)
2849 return boolean_false_node
;
2853 else if (comp
== NE_EXPR
)
2855 /* If VAL is not inside VR, then they are always different. */
2856 if (compare_values_warnv (vr
->max
, val
, strict_overflow_p
) == -1
2857 || compare_values_warnv (vr
->min
, val
, strict_overflow_p
) == 1)
2858 return boolean_true_node
;
2860 /* If VR represents exactly one value equal to VAL, then return
2862 if (compare_values_warnv (vr
->min
, vr
->max
, strict_overflow_p
) == 0
2863 && compare_values_warnv (vr
->min
, val
, strict_overflow_p
) == 0)
2864 return boolean_false_node
;
2866 /* Otherwise, they may or may not be different. */
2869 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
2873 /* If VR is to the left of VAL, return true. */
2874 tst
= compare_values_warnv (vr
->max
, val
, strict_overflow_p
);
2875 if ((comp
== LT_EXPR
&& tst
== -1)
2876 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
2878 if (overflow_infinity_range_p (vr
))
2879 *strict_overflow_p
= true;
2880 return boolean_true_node
;
2883 /* If VR is to the right of VAL, return false. */
2884 tst
= compare_values_warnv (vr
->min
, val
, strict_overflow_p
);
2885 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
2886 || (comp
== LE_EXPR
&& tst
== 1))
2888 if (overflow_infinity_range_p (vr
))
2889 *strict_overflow_p
= true;
2890 return boolean_false_node
;
2893 /* Otherwise, we don't know. */
2896 else if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
2900 /* If VR is to the right of VAL, return true. */
2901 tst
= compare_values_warnv (vr
->min
, val
, strict_overflow_p
);
2902 if ((comp
== GT_EXPR
&& tst
== 1)
2903 || (comp
== GE_EXPR
&& (tst
== 0 || tst
== 1)))
2905 if (overflow_infinity_range_p (vr
))
2906 *strict_overflow_p
= true;
2907 return boolean_true_node
;
2910 /* If VR is to the left of VAL, return false. */
2911 tst
= compare_values_warnv (vr
->max
, val
, strict_overflow_p
);
2912 if ((comp
== GT_EXPR
&& (tst
== -1 || tst
== 0))
2913 || (comp
== GE_EXPR
&& tst
== -1))
2915 if (overflow_infinity_range_p (vr
))
2916 *strict_overflow_p
= true;
2917 return boolean_false_node
;
2920 /* Otherwise, we don't know. */
2928 /* Debugging dumps. */
2930 void dump_value_range (FILE *, value_range_t
*);
2931 void debug_value_range (value_range_t
*);
2932 void dump_all_value_ranges (FILE *);
2933 void debug_all_value_ranges (void);
2934 void dump_vr_equiv (FILE *, bitmap
);
2935 void debug_vr_equiv (bitmap
);
2938 /* Dump value range VR to FILE. */
2941 dump_value_range (FILE *file
, value_range_t
*vr
)
2944 fprintf (file
, "[]");
2945 else if (vr
->type
== VR_UNDEFINED
)
2946 fprintf (file
, "UNDEFINED");
2947 else if (vr
->type
== VR_RANGE
|| vr
->type
== VR_ANTI_RANGE
)
2949 tree type
= TREE_TYPE (vr
->min
);
2951 fprintf (file
, "%s[", (vr
->type
== VR_ANTI_RANGE
) ? "~" : "");
2953 if (INTEGRAL_TYPE_P (type
)
2954 && !TYPE_UNSIGNED (type
)
2955 && vr
->min
== TYPE_MIN_VALUE (type
))
2956 fprintf (file
, "-INF");
2957 else if (needs_overflow_infinity (type
)
2958 && is_negative_overflow_infinity (vr
->min
))
2959 fprintf (file
, "-INF(OVF)");
2961 print_generic_expr (file
, vr
->min
, 0);
2963 fprintf (file
, ", ");
2965 if (INTEGRAL_TYPE_P (type
)
2966 && vr
->max
== TYPE_MAX_VALUE (type
))
2967 fprintf (file
, "+INF");
2968 else if (needs_overflow_infinity (type
)
2969 && is_positive_overflow_infinity (vr
->max
))
2970 fprintf (file
, "+INF(OVF)");
2972 print_generic_expr (file
, vr
->max
, 0);
2974 fprintf (file
, "]");
2981 fprintf (file
, " EQUIVALENCES: { ");
2983 EXECUTE_IF_SET_IN_BITMAP (vr
->equiv
, 0, i
, bi
)
2985 print_generic_expr (file
, ssa_name (i
), 0);
2986 fprintf (file
, " ");
2990 fprintf (file
, "} (%u elements)", c
);
2993 else if (vr
->type
== VR_VARYING
)
2994 fprintf (file
, "VARYING");
2996 fprintf (file
, "INVALID RANGE");
3000 /* Dump value range VR to stderr. */
3003 debug_value_range (value_range_t
*vr
)
3005 dump_value_range (stderr
, vr
);
3006 fprintf (stderr
, "\n");
3010 /* Dump value ranges of all SSA_NAMEs to FILE. */
3013 dump_all_value_ranges (FILE *file
)
3017 for (i
= 0; i
< num_ssa_names
; i
++)
3021 print_generic_expr (file
, ssa_name (i
), 0);
3022 fprintf (file
, ": ");
3023 dump_value_range (file
, vr_value
[i
]);
3024 fprintf (file
, "\n");
3028 fprintf (file
, "\n");
3032 /* Dump all value ranges to stderr. */
3035 debug_all_value_ranges (void)
3037 dump_all_value_ranges (stderr
);
3041 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
3042 create a new SSA name N and return the assertion assignment
3043 'V = ASSERT_EXPR <V, V OP W>'. */
3046 build_assert_expr_for (tree cond
, tree v
)
3050 gcc_assert (TREE_CODE (v
) == SSA_NAME
);
3051 n
= duplicate_ssa_name (v
, NULL_TREE
);
3053 if (COMPARISON_CLASS_P (cond
))
3055 tree a
= build2 (ASSERT_EXPR
, TREE_TYPE (v
), v
, cond
);
3056 assertion
= build_gimple_modify_stmt (n
, a
);
3058 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
)
3060 /* Given !V, build the assignment N = false. */
3061 tree op0
= TREE_OPERAND (cond
, 0);
3062 gcc_assert (op0
== v
);
3063 assertion
= build_gimple_modify_stmt (n
, boolean_false_node
);
3065 else if (TREE_CODE (cond
) == SSA_NAME
)
3067 /* Given V, build the assignment N = true. */
3068 gcc_assert (v
== cond
);
3069 assertion
= build_gimple_modify_stmt (n
, boolean_true_node
);
3074 SSA_NAME_DEF_STMT (n
) = assertion
;
3076 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
3077 operand of the ASSERT_EXPR. Register the new name and the old one
3078 in the replacement table so that we can fix the SSA web after
3079 adding all the ASSERT_EXPRs. */
3080 register_new_name_mapping (n
, v
);
3086 /* Return false if EXPR is a predicate expression involving floating
3090 fp_predicate (tree expr
)
3092 return (COMPARISON_CLASS_P (expr
)
3093 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr
, 0))));
3097 /* If the range of values taken by OP can be inferred after STMT executes,
3098 return the comparison code (COMP_CODE_P) and value (VAL_P) that
3099 describes the inferred range. Return true if a range could be
3103 infer_value_range (tree stmt
, tree op
, enum tree_code
*comp_code_p
, tree
*val_p
)
3106 *comp_code_p
= ERROR_MARK
;
3108 /* Do not attempt to infer anything in names that flow through
3110 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op
))
3113 /* Similarly, don't infer anything from statements that may throw
3115 if (tree_could_throw_p (stmt
))
3118 /* If STMT is the last statement of a basic block with no
3119 successors, there is no point inferring anything about any of its
3120 operands. We would not be able to find a proper insertion point
3121 for the assertion, anyway. */
3122 if (stmt_ends_bb_p (stmt
) && EDGE_COUNT (bb_for_stmt (stmt
)->succs
) == 0)
3125 /* We can only assume that a pointer dereference will yield
3126 non-NULL if -fdelete-null-pointer-checks is enabled. */
3127 if (flag_delete_null_pointer_checks
&& POINTER_TYPE_P (TREE_TYPE (op
)))
3129 unsigned num_uses
, num_loads
, num_stores
;
3131 count_uses_and_derefs (op
, stmt
, &num_uses
, &num_loads
, &num_stores
);
3132 if (num_loads
+ num_stores
> 0)
3134 *val_p
= build_int_cst (TREE_TYPE (op
), 0);
3135 *comp_code_p
= NE_EXPR
;
3144 void dump_asserts_for (FILE *, tree
);
3145 void debug_asserts_for (tree
);
3146 void dump_all_asserts (FILE *);
3147 void debug_all_asserts (void);
3149 /* Dump all the registered assertions for NAME to FILE. */
3152 dump_asserts_for (FILE *file
, tree name
)
3156 fprintf (file
, "Assertions to be inserted for ");
3157 print_generic_expr (file
, name
, 0);
3158 fprintf (file
, "\n");
3160 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
3163 fprintf (file
, "\t");
3164 print_generic_expr (file
, bsi_stmt (loc
->si
), 0);
3165 fprintf (file
, "\n\tBB #%d", loc
->bb
->index
);
3168 fprintf (file
, "\n\tEDGE %d->%d", loc
->e
->src
->index
,
3169 loc
->e
->dest
->index
);
3170 dump_edge_info (file
, loc
->e
, 0);
3172 fprintf (file
, "\n\tPREDICATE: ");
3173 print_generic_expr (file
, name
, 0);
3174 fprintf (file
, " %s ", tree_code_name
[(int)loc
->comp_code
]);
3175 print_generic_expr (file
, loc
->val
, 0);
3176 fprintf (file
, "\n\n");
3180 fprintf (file
, "\n");
3184 /* Dump all the registered assertions for NAME to stderr. */
3187 debug_asserts_for (tree name
)
3189 dump_asserts_for (stderr
, name
);
3193 /* Dump all the registered assertions for all the names to FILE. */
3196 dump_all_asserts (FILE *file
)
3201 fprintf (file
, "\nASSERT_EXPRs to be inserted\n\n");
3202 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
3203 dump_asserts_for (file
, ssa_name (i
));
3204 fprintf (file
, "\n");
3208 /* Dump all the registered assertions for all the names to stderr. */
3211 debug_all_asserts (void)
3213 dump_all_asserts (stderr
);
3217 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
3218 'NAME COMP_CODE VAL' at a location that dominates block BB or
3219 E->DEST, then register this location as a possible insertion point
3220 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
3222 BB, E and SI provide the exact insertion point for the new
3223 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
3224 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
3225 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
3226 must not be NULL. */
3229 register_new_assert_for (tree name
,
3230 enum tree_code comp_code
,
3234 block_stmt_iterator si
)
3236 assert_locus_t n
, loc
, last_loc
;
3238 basic_block dest_bb
;
3240 #if defined ENABLE_CHECKING
3241 gcc_assert (bb
== NULL
|| e
== NULL
);
3244 gcc_assert (TREE_CODE (bsi_stmt (si
)) != COND_EXPR
3245 && TREE_CODE (bsi_stmt (si
)) != SWITCH_EXPR
);
3248 /* The new assertion A will be inserted at BB or E. We need to
3249 determine if the new location is dominated by a previously
3250 registered location for A. If we are doing an edge insertion,
3251 assume that A will be inserted at E->DEST. Note that this is not
3254 If E is a critical edge, it will be split. But even if E is
3255 split, the new block will dominate the same set of blocks that
3258 The reverse, however, is not true, blocks dominated by E->DEST
3259 will not be dominated by the new block created to split E. So,
3260 if the insertion location is on a critical edge, we will not use
3261 the new location to move another assertion previously registered
3262 at a block dominated by E->DEST. */
3263 dest_bb
= (bb
) ? bb
: e
->dest
;
3265 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
3266 VAL at a block dominating DEST_BB, then we don't need to insert a new
3267 one. Similarly, if the same assertion already exists at a block
3268 dominated by DEST_BB and the new location is not on a critical
3269 edge, then update the existing location for the assertion (i.e.,
3270 move the assertion up in the dominance tree).
3272 Note, this is implemented as a simple linked list because there
3273 should not be more than a handful of assertions registered per
3274 name. If this becomes a performance problem, a table hashed by
3275 COMP_CODE and VAL could be implemented. */
3276 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
3281 if (loc
->comp_code
== comp_code
3283 || operand_equal_p (loc
->val
, val
, 0)))
3285 /* If the assertion NAME COMP_CODE VAL has already been
3286 registered at a basic block that dominates DEST_BB, then
3287 we don't need to insert the same assertion again. Note
3288 that we don't check strict dominance here to avoid
3289 replicating the same assertion inside the same basic
3290 block more than once (e.g., when a pointer is
3291 dereferenced several times inside a block).
3293 An exception to this rule are edge insertions. If the
3294 new assertion is to be inserted on edge E, then it will
3295 dominate all the other insertions that we may want to
3296 insert in DEST_BB. So, if we are doing an edge
3297 insertion, don't do this dominance check. */
3299 && dominated_by_p (CDI_DOMINATORS
, dest_bb
, loc
->bb
))
3302 /* Otherwise, if E is not a critical edge and DEST_BB
3303 dominates the existing location for the assertion, move
3304 the assertion up in the dominance tree by updating its
3305 location information. */
3306 if ((e
== NULL
|| !EDGE_CRITICAL_P (e
))
3307 && dominated_by_p (CDI_DOMINATORS
, loc
->bb
, dest_bb
))
3316 /* Update the last node of the list and move to the next one. */
3321 /* If we didn't find an assertion already registered for
3322 NAME COMP_CODE VAL, add a new one at the end of the list of
3323 assertions associated with NAME. */
3324 n
= XNEW (struct assert_locus_d
);
3328 n
->comp_code
= comp_code
;
3335 asserts_for
[SSA_NAME_VERSION (name
)] = n
;
3337 bitmap_set_bit (need_assert_for
, SSA_NAME_VERSION (name
));
3340 /* COND is a predicate which uses NAME. Extract a suitable test code
3341 and value and store them into *CODE_P and *VAL_P so the predicate
3342 is normalized to NAME *CODE_P *VAL_P.
3344 If no extraction was possible, return FALSE, otherwise return TRUE.
3346 If INVERT is true, then we invert the result stored into *CODE_P. */
3349 extract_code_and_val_from_cond (tree name
, tree cond
, bool invert
,
3350 enum tree_code
*code_p
, tree
*val_p
)
3352 enum tree_code comp_code
;
3355 /* Predicates may be a single SSA name or NAME OP VAL. */
3358 /* If the predicate is a name, it must be NAME, in which
3359 case we create the predicate NAME == true or
3360 NAME == false accordingly. */
3361 comp_code
= EQ_EXPR
;
3362 val
= invert
? boolean_false_node
: boolean_true_node
;
3366 /* Otherwise, we have a comparison of the form NAME COMP VAL
3367 or VAL COMP NAME. */
3368 if (name
== TREE_OPERAND (cond
, 1))
3370 /* If the predicate is of the form VAL COMP NAME, flip
3371 COMP around because we need to register NAME as the
3372 first operand in the predicate. */
3373 comp_code
= swap_tree_comparison (TREE_CODE (cond
));
3374 val
= TREE_OPERAND (cond
, 0);
3378 /* The comparison is of the form NAME COMP VAL, so the
3379 comparison code remains unchanged. */
3380 comp_code
= TREE_CODE (cond
);
3381 val
= TREE_OPERAND (cond
, 1);
3384 /* Invert the comparison code as necessary. */
3386 comp_code
= invert_tree_comparison (comp_code
, 0);
3388 /* VRP does not handle float types. */
3389 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val
)))
3392 /* Do not register always-false predicates.
3393 FIXME: this works around a limitation in fold() when dealing with
3394 enumerations. Given 'enum { N1, N2 } x;', fold will not
3395 fold 'if (x > N2)' to 'if (0)'. */
3396 if ((comp_code
== GT_EXPR
|| comp_code
== LT_EXPR
)
3397 && INTEGRAL_TYPE_P (TREE_TYPE (val
)))
3399 tree min
= TYPE_MIN_VALUE (TREE_TYPE (val
));
3400 tree max
= TYPE_MAX_VALUE (TREE_TYPE (val
));
3402 if (comp_code
== GT_EXPR
3404 || compare_values (val
, max
) == 0))
3407 if (comp_code
== LT_EXPR
3409 || compare_values (val
, min
) == 0))
3413 *code_p
= comp_code
;
3418 /* OP is an operand of a truth value expression which is known to have
3419 a particular value. Register any asserts for OP and for any
3420 operands in OP's defining statement.
3422 If CODE is EQ_EXPR, then we want to register OP is zero (false),
3423 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
3426 register_edge_assert_for_1 (tree op
, enum tree_code code
,
3427 edge e
, block_stmt_iterator bsi
)
3429 bool retval
= false;
3430 tree op_def
, rhs
, val
;
3432 /* We only care about SSA_NAMEs. */
3433 if (TREE_CODE (op
) != SSA_NAME
)
3436 /* We know that OP will have a zero or nonzero value. If OP is used
3437 more than once go ahead and register an assert for OP.
3439 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
3440 it will always be set for OP (because OP is used in a COND_EXPR in
3442 if (!has_single_use (op
))
3444 val
= build_int_cst (TREE_TYPE (op
), 0);
3445 register_new_assert_for (op
, code
, val
, NULL
, e
, bsi
);
3449 /* Now look at how OP is set. If it's set from a comparison,
3450 a truth operation or some bit operations, then we may be able
3451 to register information about the operands of that assignment. */
3452 op_def
= SSA_NAME_DEF_STMT (op
);
3453 if (TREE_CODE (op_def
) != GIMPLE_MODIFY_STMT
)
3456 rhs
= GIMPLE_STMT_OPERAND (op_def
, 1);
3458 if (COMPARISON_CLASS_P (rhs
))
3460 bool invert
= (code
== EQ_EXPR
? true : false);
3461 tree op0
= TREE_OPERAND (rhs
, 0);
3462 tree op1
= TREE_OPERAND (rhs
, 1);
3464 /* Conditionally register an assert for each SSA_NAME in the
3466 if (TREE_CODE (op0
) == SSA_NAME
3467 && !has_single_use (op0
)
3468 && extract_code_and_val_from_cond (op0
, rhs
,
3469 invert
, &code
, &val
))
3471 register_new_assert_for (op0
, code
, val
, NULL
, e
, bsi
);
3475 /* Similarly for the second operand of the comparison. */
3476 if (TREE_CODE (op1
) == SSA_NAME
3477 && !has_single_use (op1
)
3478 && extract_code_and_val_from_cond (op1
, rhs
,
3479 invert
, &code
, &val
))
3481 register_new_assert_for (op1
, code
, val
, NULL
, e
, bsi
);
3485 else if ((code
== NE_EXPR
3486 && (TREE_CODE (rhs
) == TRUTH_AND_EXPR
3487 || TREE_CODE (rhs
) == BIT_AND_EXPR
))
3489 && (TREE_CODE (rhs
) == TRUTH_OR_EXPR
3490 || TREE_CODE (rhs
) == BIT_IOR_EXPR
)))
3492 /* Recurse on each operand. */
3493 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 0),
3495 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 1),
3498 else if (TREE_CODE (rhs
) == TRUTH_NOT_EXPR
)
3500 /* Recurse, flipping CODE. */
3501 code
= invert_tree_comparison (code
, false);
3502 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 0),
3505 else if (TREE_CODE (rhs
) == SSA_NAME
)
3507 /* Recurse through the copy. */
3508 retval
|= register_edge_assert_for_1 (rhs
, code
, e
, bsi
);
3510 else if (TREE_CODE (rhs
) == NOP_EXPR
3511 || TREE_CODE (rhs
) == CONVERT_EXPR
3512 || TREE_CODE (rhs
) == NON_LVALUE_EXPR
)
3514 /* Recurse through the type conversion. */
3515 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 0),
3522 /* Try to register an edge assertion for SSA name NAME on edge E for
3523 the condition COND contributing to the conditional jump pointed to by SI.
3524 Return true if an assertion for NAME could be registered. */
3527 register_edge_assert_for (tree name
, edge e
, block_stmt_iterator si
, tree cond
)
3530 enum tree_code comp_code
;
3531 bool retval
= false;
3532 bool is_else_edge
= (e
->flags
& EDGE_FALSE_VALUE
) != 0;
3534 /* Do not attempt to infer anything in names that flow through
3536 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name
))
3539 if (!extract_code_and_val_from_cond (name
, cond
, is_else_edge
,
3543 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
3544 reachable from E. */
3545 if (TEST_BIT (found_in_subgraph
, SSA_NAME_VERSION (name
)))
3547 register_new_assert_for (name
, comp_code
, val
, NULL
, e
, si
);
3551 /* If COND is effectively an equality test of an SSA_NAME against
3552 the value zero or one, then we may be able to assert values
3553 for SSA_NAMEs which flow into COND. */
3555 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
3556 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
3557 have nonzero value. */
3558 if (((comp_code
== EQ_EXPR
&& integer_onep (val
))
3559 || (comp_code
== NE_EXPR
&& integer_zerop (val
))))
3561 tree def_stmt
= SSA_NAME_DEF_STMT (name
);
3563 if (TREE_CODE (def_stmt
) == GIMPLE_MODIFY_STMT
3564 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == TRUTH_AND_EXPR
3565 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == BIT_AND_EXPR
))
3567 tree op0
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 0);
3568 tree op1
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 1);
3569 retval
|= register_edge_assert_for_1 (op0
, NE_EXPR
, e
, si
);
3570 retval
|= register_edge_assert_for_1 (op1
, NE_EXPR
, e
, si
);
3574 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
3575 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
3577 if (((comp_code
== EQ_EXPR
&& integer_zerop (val
))
3578 || (comp_code
== NE_EXPR
&& integer_onep (val
))))
3580 tree def_stmt
= SSA_NAME_DEF_STMT (name
);
3582 if (TREE_CODE (def_stmt
) == GIMPLE_MODIFY_STMT
3583 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == TRUTH_OR_EXPR
3584 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == BIT_IOR_EXPR
))
3586 tree op0
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 0);
3587 tree op1
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 1);
3588 retval
|= register_edge_assert_for_1 (op0
, EQ_EXPR
, e
, si
);
3589 retval
|= register_edge_assert_for_1 (op1
, EQ_EXPR
, e
, si
);
3597 static bool find_assert_locations (basic_block bb
);
3599 /* Determine whether the outgoing edges of BB should receive an
3600 ASSERT_EXPR for each of the operands of BB's LAST statement.
3601 The last statement of BB must be a COND_EXPR.
3603 If any of the sub-graphs rooted at BB have an interesting use of
3604 the predicate operands, an assert location node is added to the
3605 list of assertions for the corresponding operands. */
3608 find_conditional_asserts (basic_block bb
, tree last
)
3611 block_stmt_iterator bsi
;
3617 need_assert
= false;
3618 bsi
= bsi_for_stmt (last
);
3620 /* Look for uses of the operands in each of the sub-graphs
3621 rooted at BB. We need to check each of the outgoing edges
3622 separately, so that we know what kind of ASSERT_EXPR to
3624 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3629 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
3630 Otherwise, when we finish traversing each of the sub-graphs, we
3631 won't know whether the variables were found in the sub-graphs or
3632 if they had been found in a block upstream from BB.
3634 This is actually a bad idea is some cases, particularly jump
3635 threading. Consider a CFG like the following:
3645 Assume that one or more operands in the conditional at the
3646 end of block 0 are used in a conditional in block 2, but not
3647 anywhere in block 1. In this case we will not insert any
3648 assert statements in block 1, which may cause us to miss
3649 opportunities to optimize, particularly for jump threading. */
3650 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
3651 RESET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3653 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3654 to determine if any of the operands in the conditional
3655 predicate are used. */
3657 need_assert
|= find_assert_locations (e
->dest
);
3659 /* Register the necessary assertions for each operand in the
3660 conditional predicate. */
3661 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
3662 need_assert
|= register_edge_assert_for (op
, e
, bsi
,
3663 COND_EXPR_COND (last
));
3666 /* Finally, indicate that we have found the operands in the
3668 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
3669 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3674 /* Compare two case labels sorting first by the destination label uid
3675 and then by the case value. */
3678 compare_case_labels (const void *p1
, const void *p2
)
3680 tree case1
= *(tree
*)p1
;
3681 tree case2
= *(tree
*)p2
;
3682 unsigned int uid1
= DECL_UID (CASE_LABEL (case1
));
3683 unsigned int uid2
= DECL_UID (CASE_LABEL (case2
));
3687 else if (uid1
== uid2
)
3689 /* Make sure the default label is first in a group. */
3690 if (!CASE_LOW (case1
))
3692 else if (!CASE_LOW (case2
))
3695 return tree_int_cst_compare (CASE_LOW (case1
), CASE_LOW (case2
));
3701 /* Determine whether the outgoing edges of BB should receive an
3702 ASSERT_EXPR for each of the operands of BB's LAST statement.
3703 The last statement of BB must be a SWITCH_EXPR.
3705 If any of the sub-graphs rooted at BB have an interesting use of
3706 the predicate operands, an assert location node is added to the
3707 list of assertions for the corresponding operands. */
3710 find_switch_asserts (basic_block bb
, tree last
)
3713 block_stmt_iterator bsi
;
3716 tree vec
= SWITCH_LABELS (last
), vec2
;
3717 size_t n
= TREE_VEC_LENGTH (vec
);
3720 need_assert
= false;
3721 bsi
= bsi_for_stmt (last
);
3722 op
= TREE_OPERAND (last
, 0);
3723 if (TREE_CODE (op
) != SSA_NAME
)
3726 /* Build a vector of case labels sorted by destination label. */
3727 vec2
= make_tree_vec (n
);
3728 for (idx
= 0; idx
< n
; ++idx
)
3729 TREE_VEC_ELT (vec2
, idx
) = TREE_VEC_ELT (vec
, idx
);
3730 qsort (&TREE_VEC_ELT (vec2
, 0), n
, sizeof (tree
), compare_case_labels
);
3732 for (idx
= 0; idx
< n
; ++idx
)
3735 tree cl
= TREE_VEC_ELT (vec2
, idx
);
3737 min
= CASE_LOW (cl
);
3738 max
= CASE_HIGH (cl
);
3740 /* If there are multiple case labels with the same destination
3741 we need to combine them to a single value range for the edge. */
3743 && CASE_LABEL (cl
) == CASE_LABEL (TREE_VEC_ELT (vec2
, idx
+ 1)))
3745 /* Skip labels until the last of the group. */
3749 && CASE_LABEL (cl
) == CASE_LABEL (TREE_VEC_ELT (vec2
, idx
)));
3752 /* Pick up the maximum of the case label range. */
3753 if (CASE_HIGH (TREE_VEC_ELT (vec2
, idx
)))
3754 max
= CASE_HIGH (TREE_VEC_ELT (vec2
, idx
));
3756 max
= CASE_LOW (TREE_VEC_ELT (vec2
, idx
));
3759 /* Nothing to do if the range includes the default label until we
3760 can register anti-ranges. */
3761 if (min
== NULL_TREE
)
3764 /* Find the edge to register the assert expr on. */
3765 e
= find_edge (bb
, label_to_block (CASE_LABEL (cl
)));
3767 /* Remove the SWITCH_EXPR operand from the FOUND_IN_SUBGRAPH bitmap.
3768 Otherwise, when we finish traversing each of the sub-graphs, we
3769 won't know whether the variables were found in the sub-graphs or
3770 if they had been found in a block upstream from BB. */
3771 RESET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3773 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3774 to determine if any of the operands in the conditional
3775 predicate are used. */
3777 need_assert
|= find_assert_locations (e
->dest
);
3779 /* Register the necessary assertions for the operand in the
3781 cond
= build2 (max
? GE_EXPR
: EQ_EXPR
, boolean_type_node
,
3782 op
, fold_convert (TREE_TYPE (op
), min
));
3783 need_assert
|= register_edge_assert_for (op
, e
, bsi
, cond
);
3786 cond
= build2 (LE_EXPR
, boolean_type_node
,
3787 op
, fold_convert (TREE_TYPE (op
), max
));
3788 need_assert
|= register_edge_assert_for (op
, e
, bsi
, cond
);
3792 /* Finally, indicate that we have found the operand in the
3794 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3800 /* Traverse all the statements in block BB looking for statements that
3801 may generate useful assertions for the SSA names in their operand.
3802 If a statement produces a useful assertion A for name N_i, then the
3803 list of assertions already generated for N_i is scanned to
3804 determine if A is actually needed.
3806 If N_i already had the assertion A at a location dominating the
3807 current location, then nothing needs to be done. Otherwise, the
3808 new location for A is recorded instead.
3810 1- For every statement S in BB, all the variables used by S are
3811 added to bitmap FOUND_IN_SUBGRAPH.
3813 2- If statement S uses an operand N in a way that exposes a known
3814 value range for N, then if N was not already generated by an
3815 ASSERT_EXPR, create a new assert location for N. For instance,
3816 if N is a pointer and the statement dereferences it, we can
3817 assume that N is not NULL.
3819 3- COND_EXPRs are a special case of #2. We can derive range
3820 information from the predicate but need to insert different
3821 ASSERT_EXPRs for each of the sub-graphs rooted at the
3822 conditional block. If the last statement of BB is a conditional
3823 expression of the form 'X op Y', then
3825 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
3827 b) If the conditional is the only entry point to the sub-graph
3828 corresponding to the THEN_CLAUSE, recurse into it. On
3829 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
3830 an ASSERT_EXPR is added for the corresponding variable.
3832 c) Repeat step (b) on the ELSE_CLAUSE.
3834 d) Mark X and Y in FOUND_IN_SUBGRAPH.
3843 In this case, an assertion on the THEN clause is useful to
3844 determine that 'a' is always 9 on that edge. However, an assertion
3845 on the ELSE clause would be unnecessary.
3847 4- If BB does not end in a conditional expression, then we recurse
3848 into BB's dominator children.
3850 At the end of the recursive traversal, every SSA name will have a
3851 list of locations where ASSERT_EXPRs should be added. When a new
3852 location for name N is found, it is registered by calling
3853 register_new_assert_for. That function keeps track of all the
3854 registered assertions to prevent adding unnecessary assertions.
3855 For instance, if a pointer P_4 is dereferenced more than once in a
3856 dominator tree, only the location dominating all the dereference of
3857 P_4 will receive an ASSERT_EXPR.
3859 If this function returns true, then it means that there are names
3860 for which we need to generate ASSERT_EXPRs. Those assertions are
3861 inserted by process_assert_insertions. */
3864 find_assert_locations (basic_block bb
)
3866 block_stmt_iterator si
;
3871 if (TEST_BIT (blocks_visited
, bb
->index
))
3874 SET_BIT (blocks_visited
, bb
->index
);
3876 need_assert
= false;
3878 /* Traverse all PHI nodes in BB marking used operands. */
3879 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3881 use_operand_p arg_p
;
3884 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_USE
)
3886 tree arg
= USE_FROM_PTR (arg_p
);
3887 if (TREE_CODE (arg
) == SSA_NAME
)
3889 gcc_assert (is_gimple_reg (PHI_RESULT (phi
)));
3890 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (arg
));
3895 /* Traverse all the statements in BB marking used names and looking
3896 for statements that may infer assertions for their used operands. */
3898 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
3903 stmt
= bsi_stmt (si
);
3905 /* See if we can derive an assertion for any of STMT's operands. */
3906 FOR_EACH_SSA_TREE_OPERAND (op
, stmt
, i
, SSA_OP_USE
)
3909 enum tree_code comp_code
;
3911 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
3912 the sub-graph of a conditional block, when we return from
3913 this recursive walk, our parent will use the
3914 FOUND_IN_SUBGRAPH bitset to determine if one of the
3915 operands it was looking for was present in the sub-graph. */
3916 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3918 /* If OP is used in such a way that we can infer a value
3919 range for it, and we don't find a previous assertion for
3920 it, create a new assertion location node for OP. */
3921 if (infer_value_range (stmt
, op
, &comp_code
, &value
))
3923 /* If we are able to infer a nonzero value range for OP,
3924 then walk backwards through the use-def chain to see if OP
3925 was set via a typecast.
3927 If so, then we can also infer a nonzero value range
3928 for the operand of the NOP_EXPR. */
3929 if (comp_code
== NE_EXPR
&& integer_zerop (value
))
3932 tree def_stmt
= SSA_NAME_DEF_STMT (t
);
3934 while (TREE_CODE (def_stmt
) == GIMPLE_MODIFY_STMT
3936 (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == NOP_EXPR
3938 (TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1),
3941 (TREE_TYPE (TREE_OPERAND
3942 (GIMPLE_STMT_OPERAND (def_stmt
,
3945 t
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 0);
3946 def_stmt
= SSA_NAME_DEF_STMT (t
);
3948 /* Note we want to register the assert for the
3949 operand of the NOP_EXPR after SI, not after the
3951 if (! has_single_use (t
))
3953 register_new_assert_for (t
, comp_code
, value
,
3960 /* If OP is used only once, namely in this STMT, don't
3961 bother creating an ASSERT_EXPR for it. Such an
3962 ASSERT_EXPR would do nothing but increase compile time. */
3963 if (!has_single_use (op
))
3965 register_new_assert_for (op
, comp_code
, value
, bb
, NULL
, si
);
3971 /* Remember the last statement of the block. */
3975 /* If BB's last statement is a conditional expression
3976 involving integer operands, recurse into each of the sub-graphs
3977 rooted at BB to determine if we need to add ASSERT_EXPRs. */
3979 && TREE_CODE (last
) == COND_EXPR
3980 && !fp_predicate (COND_EXPR_COND (last
))
3981 && !ZERO_SSA_OPERANDS (last
, SSA_OP_USE
))
3982 need_assert
|= find_conditional_asserts (bb
, last
);
3985 && TREE_CODE (last
) == SWITCH_EXPR
3986 && !ZERO_SSA_OPERANDS (last
, SSA_OP_USE
))
3987 need_assert
|= find_switch_asserts (bb
, last
);
3989 /* Recurse into the dominator children of BB. */
3990 for (son
= first_dom_son (CDI_DOMINATORS
, bb
);
3992 son
= next_dom_son (CDI_DOMINATORS
, son
))
3993 need_assert
|= find_assert_locations (son
);
3999 /* Create an ASSERT_EXPR for NAME and insert it in the location
4000 indicated by LOC. Return true if we made any edge insertions. */
4003 process_assert_insertions_for (tree name
, assert_locus_t loc
)
4005 /* Build the comparison expression NAME_i COMP_CODE VAL. */
4006 tree stmt
, cond
, assert_expr
;
4010 cond
= build2 (loc
->comp_code
, boolean_type_node
, name
, loc
->val
);
4011 assert_expr
= build_assert_expr_for (cond
, name
);
4015 /* We have been asked to insert the assertion on an edge. This
4016 is used only by COND_EXPR and SWITCH_EXPR assertions. */
4017 #if defined ENABLE_CHECKING
4018 gcc_assert (TREE_CODE (bsi_stmt (loc
->si
)) == COND_EXPR
4019 || TREE_CODE (bsi_stmt (loc
->si
)) == SWITCH_EXPR
);
4022 bsi_insert_on_edge (loc
->e
, assert_expr
);
4026 /* Otherwise, we can insert right after LOC->SI iff the
4027 statement must not be the last statement in the block. */
4028 stmt
= bsi_stmt (loc
->si
);
4029 if (!stmt_ends_bb_p (stmt
))
4031 bsi_insert_after (&loc
->si
, assert_expr
, BSI_SAME_STMT
);
4035 /* If STMT must be the last statement in BB, we can only insert new
4036 assertions on the non-abnormal edge out of BB. Note that since
4037 STMT is not control flow, there may only be one non-abnormal edge
4039 FOR_EACH_EDGE (e
, ei
, loc
->bb
->succs
)
4040 if (!(e
->flags
& EDGE_ABNORMAL
))
4042 bsi_insert_on_edge (e
, assert_expr
);
4050 /* Process all the insertions registered for every name N_i registered
4051 in NEED_ASSERT_FOR. The list of assertions to be inserted are
4052 found in ASSERTS_FOR[i]. */
4055 process_assert_insertions (void)
4059 bool update_edges_p
= false;
4060 int num_asserts
= 0;
4062 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4063 dump_all_asserts (dump_file
);
4065 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
4067 assert_locus_t loc
= asserts_for
[i
];
4072 assert_locus_t next
= loc
->next
;
4073 update_edges_p
|= process_assert_insertions_for (ssa_name (i
), loc
);
4081 bsi_commit_edge_inserts ();
4083 if (dump_file
&& (dump_flags
& TDF_STATS
))
4084 fprintf (dump_file
, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
4089 /* Traverse the flowgraph looking for conditional jumps to insert range
4090 expressions. These range expressions are meant to provide information
4091 to optimizations that need to reason in terms of value ranges. They
4092 will not be expanded into RTL. For instance, given:
4101 this pass will transform the code into:
4107 x = ASSERT_EXPR <x, x < y>
4112 y = ASSERT_EXPR <y, x <= y>
4116 The idea is that once copy and constant propagation have run, other
4117 optimizations will be able to determine what ranges of values can 'x'
4118 take in different paths of the code, simply by checking the reaching
4119 definition of 'x'. */
4122 insert_range_assertions (void)
4128 found_in_subgraph
= sbitmap_alloc (num_ssa_names
);
4129 sbitmap_zero (found_in_subgraph
);
4131 blocks_visited
= sbitmap_alloc (last_basic_block
);
4132 sbitmap_zero (blocks_visited
);
4134 need_assert_for
= BITMAP_ALLOC (NULL
);
4135 asserts_for
= XCNEWVEC (assert_locus_t
, num_ssa_names
);
4137 calculate_dominance_info (CDI_DOMINATORS
);
4139 update_ssa_p
= false;
4140 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
4141 if (find_assert_locations (e
->dest
))
4142 update_ssa_p
= true;
4146 process_assert_insertions ();
4147 update_ssa (TODO_update_ssa_no_phi
);
4150 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4152 fprintf (dump_file
, "\nSSA form after inserting ASSERT_EXPRs\n");
4153 dump_function_to_file (current_function_decl
, dump_file
, dump_flags
);
4156 sbitmap_free (found_in_subgraph
);
4158 BITMAP_FREE (need_assert_for
);
4161 /* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays
4162 and "struct" hacks. If VRP can determine that the
4163 array subscript is a constant, check if it is outside valid
4164 range. If the array subscript is a RANGE, warn if it is
4165 non-overlapping with valid range.
4166 IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */
4169 check_array_ref (tree ref
, location_t
* locus
, bool ignore_off_by_one
)
4171 value_range_t
* vr
= NULL
;
4172 tree low_sub
, up_sub
;
4173 tree low_bound
, up_bound
= array_ref_up_bound (ref
);
4175 low_sub
= up_sub
= TREE_OPERAND (ref
, 1);
4177 if (!up_bound
|| !locus
|| TREE_NO_WARNING (ref
)
4178 || TREE_CODE (up_bound
) != INTEGER_CST
4179 /* Can not check flexible arrays. */
4180 || (TYPE_SIZE (TREE_TYPE (ref
)) == NULL_TREE
4181 && TYPE_DOMAIN (TREE_TYPE (ref
)) != NULL_TREE
4182 && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (ref
))) == NULL_TREE
)
4183 /* Accesses after the end of arrays of size 0 (gcc
4184 extension) and 1 are likely intentional ("struct
4186 || compare_tree_int (up_bound
, 1) <= 0)
4189 low_bound
= array_ref_low_bound (ref
);
4191 if (TREE_CODE (low_sub
) == SSA_NAME
)
4193 vr
= get_value_range (low_sub
);
4194 if (vr
->type
== VR_RANGE
|| vr
->type
== VR_ANTI_RANGE
)
4196 low_sub
= vr
->type
== VR_RANGE
? vr
->max
: vr
->min
;
4197 up_sub
= vr
->type
== VR_RANGE
? vr
->min
: vr
->max
;
4201 if (vr
&& vr
->type
== VR_ANTI_RANGE
)
4203 if (TREE_CODE (up_sub
) == INTEGER_CST
4204 && tree_int_cst_lt (up_bound
, up_sub
)
4205 && TREE_CODE (low_sub
) == INTEGER_CST
4206 && tree_int_cst_lt (low_sub
, low_bound
))
4208 warning (OPT_Warray_bounds
,
4209 "%Harray subscript is outside array bounds", locus
);
4210 TREE_NO_WARNING (ref
) = 1;
4213 else if (TREE_CODE (up_sub
) == INTEGER_CST
4214 && tree_int_cst_lt (up_bound
, up_sub
)
4215 && !tree_int_cst_equal (up_bound
, up_sub
)
4216 && (!ignore_off_by_one
4217 || !tree_int_cst_equal (int_const_binop (PLUS_EXPR
,
4223 warning (OPT_Warray_bounds
, "%Harray subscript is above array bounds",
4225 TREE_NO_WARNING (ref
) = 1;
4227 else if (TREE_CODE (low_sub
) == INTEGER_CST
4228 && tree_int_cst_lt (low_sub
, low_bound
))
4230 warning (OPT_Warray_bounds
, "%Harray subscript is below array bounds",
4232 TREE_NO_WARNING (ref
) = 1;
4236 /* walk_tree() callback that checks if *TP is
4237 an ARRAY_REF inside an ADDR_EXPR (in which an array
4238 subscript one outside the valid range is allowed). Call
4239 check_array_ref for each ARRAY_REF found. The location is
4243 check_array_bounds (tree
*tp
, int *walk_subtree
, void *data
)
4246 tree stmt
= (tree
)data
;
4247 location_t
*location
= EXPR_LOCUS (stmt
);
4249 *walk_subtree
= TRUE
;
4251 if (TREE_CODE (t
) == ARRAY_REF
)
4252 check_array_ref (t
, location
, false /*ignore_off_by_one*/);
4253 else if (TREE_CODE (t
) == ADDR_EXPR
)
4257 t
= TREE_OPERAND (t
, 0);
4259 /* Don't warn on statements like
4261 ssa_name = 500 + &array[-200]
4265 ssa_name = &array[-200]
4266 other_name = ssa_name + 300;
4269 produced by other optimizing passes. */
4271 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
4272 && BINARY_CLASS_P (GIMPLE_STMT_OPERAND (stmt
, 1)))
4273 *walk_subtree
= FALSE
;
4275 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
4276 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt
, 0)) == SSA_NAME
4277 && single_imm_use (GIMPLE_STMT_OPERAND (stmt
, 0), &op
, &use_stmt
)
4278 && TREE_CODE (use_stmt
) == GIMPLE_MODIFY_STMT
4279 && BINARY_CLASS_P (GIMPLE_STMT_OPERAND (use_stmt
, 1)))
4280 *walk_subtree
= FALSE
;
4282 while (*walk_subtree
&& handled_component_p (t
))
4284 if (TREE_CODE (t
) == ARRAY_REF
)
4285 check_array_ref (t
, location
, true /*ignore_off_by_one*/);
4286 t
= TREE_OPERAND (t
, 0);
4288 *walk_subtree
= FALSE
;
4294 /* Walk over all statements of all reachable BBs and call check_array_bounds
4298 check_all_array_refs (void)
4301 block_stmt_iterator si
;
4305 /* Skip bb's that are clearly unreachable. */
4306 if (single_pred_p (bb
))
4308 basic_block pred_bb
= EDGE_PRED (bb
, 0)->src
;
4309 tree ls
= NULL_TREE
;
4311 if (!bsi_end_p (bsi_last (pred_bb
)))
4312 ls
= bsi_stmt (bsi_last (pred_bb
));
4314 if (ls
&& TREE_CODE (ls
) == COND_EXPR
4315 && ((COND_EXPR_COND (ls
) == boolean_false_node
4316 && (EDGE_PRED (bb
, 0)->flags
& EDGE_TRUE_VALUE
))
4317 || (COND_EXPR_COND (ls
) == boolean_true_node
4318 && (EDGE_PRED (bb
, 0)->flags
& EDGE_FALSE_VALUE
))))
4321 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
4322 walk_tree (bsi_stmt_ptr (si
), check_array_bounds
,
4323 bsi_stmt (si
), NULL
);
4327 /* Convert range assertion expressions into the implied copies and
4328 copy propagate away the copies. Doing the trivial copy propagation
4329 here avoids the need to run the full copy propagation pass after
4332 FIXME, this will eventually lead to copy propagation removing the
4333 names that had useful range information attached to them. For
4334 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
4335 then N_i will have the range [3, +INF].
4337 However, by converting the assertion into the implied copy
4338 operation N_i = N_j, we will then copy-propagate N_j into the uses
4339 of N_i and lose the range information. We may want to hold on to
4340 ASSERT_EXPRs a little while longer as the ranges could be used in
4341 things like jump threading.
4343 The problem with keeping ASSERT_EXPRs around is that passes after
4344 VRP need to handle them appropriately.
4346 Another approach would be to make the range information a first
4347 class property of the SSA_NAME so that it can be queried from
4348 any pass. This is made somewhat more complex by the need for
4349 multiple ranges to be associated with one SSA_NAME. */
4352 remove_range_assertions (void)
4355 block_stmt_iterator si
;
4357 /* Note that the BSI iterator bump happens at the bottom of the
4358 loop and no bump is necessary if we're removing the statement
4359 referenced by the current BSI. */
4361 for (si
= bsi_start (bb
); !bsi_end_p (si
);)
4363 tree stmt
= bsi_stmt (si
);
4366 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
4367 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt
, 1)) == ASSERT_EXPR
)
4369 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1), var
;
4370 tree cond
= fold (ASSERT_EXPR_COND (rhs
));
4371 use_operand_p use_p
;
4372 imm_use_iterator iter
;
4374 gcc_assert (cond
!= boolean_false_node
);
4376 /* Propagate the RHS into every use of the LHS. */
4377 var
= ASSERT_EXPR_VAR (rhs
);
4378 FOR_EACH_IMM_USE_STMT (use_stmt
, iter
,
4379 GIMPLE_STMT_OPERAND (stmt
, 0))
4380 FOR_EACH_IMM_USE_ON_STMT (use_p
, iter
)
4382 SET_USE (use_p
, var
);
4383 gcc_assert (TREE_CODE (var
) == SSA_NAME
);
4386 /* And finally, remove the copy, it is not needed. */
4387 bsi_remove (&si
, true);
4388 release_defs (stmt
);
4394 sbitmap_free (blocks_visited
);
4398 /* Return true if STMT is interesting for VRP. */
4401 stmt_interesting_for_vrp (tree stmt
)
4403 if (TREE_CODE (stmt
) == PHI_NODE
4404 && is_gimple_reg (PHI_RESULT (stmt
))
4405 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))
4406 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))))
4408 else if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
4410 tree lhs
= GIMPLE_STMT_OPERAND (stmt
, 0);
4411 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
4413 /* In general, assignments with virtual operands are not useful
4414 for deriving ranges, with the obvious exception of calls to
4415 builtin functions. */
4416 if (TREE_CODE (lhs
) == SSA_NAME
4417 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
4418 || POINTER_TYPE_P (TREE_TYPE (lhs
)))
4419 && ((TREE_CODE (rhs
) == CALL_EXPR
4420 && TREE_CODE (CALL_EXPR_FN (rhs
)) == ADDR_EXPR
4421 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs
), 0))
4422 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs
), 0)))
4423 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
)))
4426 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
4433 /* Initialize local data structures for VRP. */
4436 vrp_initialize (void)
4440 vr_value
= XCNEWVEC (value_range_t
*, num_ssa_names
);
4441 vr_phi_edge_counts
= XCNEWVEC (int, num_ssa_names
);
4445 block_stmt_iterator si
;
4448 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
4450 if (!stmt_interesting_for_vrp (phi
))
4452 tree lhs
= PHI_RESULT (phi
);
4453 set_value_range_to_varying (get_value_range (lhs
));
4454 DONT_SIMULATE_AGAIN (phi
) = true;
4457 DONT_SIMULATE_AGAIN (phi
) = false;
4460 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
4462 tree stmt
= bsi_stmt (si
);
4464 if (!stmt_interesting_for_vrp (stmt
))
4468 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, i
, SSA_OP_DEF
)
4469 set_value_range_to_varying (get_value_range (def
));
4470 DONT_SIMULATE_AGAIN (stmt
) = true;
4474 DONT_SIMULATE_AGAIN (stmt
) = false;
4481 /* Visit assignment STMT. If it produces an interesting range, record
4482 the SSA name in *OUTPUT_P. */
4484 static enum ssa_prop_result
4485 vrp_visit_assignment (tree stmt
, tree
*output_p
)
4490 lhs
= GIMPLE_STMT_OPERAND (stmt
, 0);
4491 rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
4493 /* We only keep track of ranges in integral and pointer types. */
4494 if (TREE_CODE (lhs
) == SSA_NAME
4495 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
4496 /* It is valid to have NULL MIN/MAX values on a type. See
4497 build_range_type. */
4498 && TYPE_MIN_VALUE (TREE_TYPE (lhs
))
4499 && TYPE_MAX_VALUE (TREE_TYPE (lhs
)))
4500 || POINTER_TYPE_P (TREE_TYPE (lhs
))))
4503 value_range_t new_vr
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
4505 extract_range_from_expr (&new_vr
, rhs
);
4507 /* If STMT is inside a loop, we may be able to know something
4508 else about the range of LHS by examining scalar evolution
4510 if (current_loops
&& (l
= loop_containing_stmt (stmt
)))
4511 adjust_range_with_scev (&new_vr
, l
, stmt
, lhs
);
4513 if (update_value_range (lhs
, &new_vr
))
4517 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4519 fprintf (dump_file
, "Found new range for ");
4520 print_generic_expr (dump_file
, lhs
, 0);
4521 fprintf (dump_file
, ": ");
4522 dump_value_range (dump_file
, &new_vr
);
4523 fprintf (dump_file
, "\n\n");
4526 if (new_vr
.type
== VR_VARYING
)
4527 return SSA_PROP_VARYING
;
4529 return SSA_PROP_INTERESTING
;
4532 return SSA_PROP_NOT_INTERESTING
;
4535 /* Every other statement produces no useful ranges. */
4536 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
4537 set_value_range_to_varying (get_value_range (def
));
4539 return SSA_PROP_VARYING
;
4543 /* Compare all the value ranges for names equivalent to VAR with VAL
4544 using comparison code COMP. Return the same value returned by
4545 compare_range_with_value, including the setting of
4546 *STRICT_OVERFLOW_P. */
4549 compare_name_with_value (enum tree_code comp
, tree var
, tree val
,
4550 bool *strict_overflow_p
)
4556 int used_strict_overflow
;
4558 t
= retval
= NULL_TREE
;
4560 /* Get the set of equivalences for VAR. */
4561 e
= get_value_range (var
)->equiv
;
4563 /* Add VAR to its own set of equivalences so that VAR's value range
4564 is processed by this loop (otherwise, we would have to replicate
4565 the body of the loop just to check VAR's value range). */
4566 bitmap_set_bit (e
, SSA_NAME_VERSION (var
));
4568 /* Start at -1. Set it to 0 if we do a comparison without relying
4569 on overflow, or 1 if all comparisons rely on overflow. */
4570 used_strict_overflow
= -1;
4572 EXECUTE_IF_SET_IN_BITMAP (e
, 0, i
, bi
)
4576 value_range_t equiv_vr
= *(vr_value
[i
]);
4578 /* If name N_i does not have a valid range, use N_i as its own
4579 range. This allows us to compare against names that may
4580 have N_i in their ranges. */
4581 if (equiv_vr
.type
== VR_VARYING
|| equiv_vr
.type
== VR_UNDEFINED
)
4583 equiv_vr
.type
= VR_RANGE
;
4584 equiv_vr
.min
= ssa_name (i
);
4585 equiv_vr
.max
= ssa_name (i
);
4589 t
= compare_range_with_value (comp
, &equiv_vr
, val
, &sop
);
4592 /* If we get different answers from different members
4593 of the equivalence set this check must be in a dead
4594 code region. Folding it to a trap representation
4595 would be correct here. For now just return don't-know. */
4605 used_strict_overflow
= 0;
4606 else if (used_strict_overflow
< 0)
4607 used_strict_overflow
= 1;
4611 /* Remove VAR from its own equivalence set. */
4612 bitmap_clear_bit (e
, SSA_NAME_VERSION (var
));
4616 if (used_strict_overflow
> 0)
4617 *strict_overflow_p
= true;
4621 /* We couldn't find a non-NULL value for the predicate. */
4626 /* Given a comparison code COMP and names N1 and N2, compare all the
4627 ranges equivalent to N1 against all the ranges equivalent to N2
4628 to determine the value of N1 COMP N2. Return the same value
4629 returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate
4630 whether we relied on an overflow infinity in the comparison. */
4634 compare_names (enum tree_code comp
, tree n1
, tree n2
,
4635 bool *strict_overflow_p
)
4639 bitmap_iterator bi1
, bi2
;
4641 int used_strict_overflow
;
4643 /* Compare the ranges of every name equivalent to N1 against the
4644 ranges of every name equivalent to N2. */
4645 e1
= get_value_range (n1
)->equiv
;
4646 e2
= get_value_range (n2
)->equiv
;
4648 /* Add N1 and N2 to their own set of equivalences to avoid
4649 duplicating the body of the loop just to check N1 and N2
4651 bitmap_set_bit (e1
, SSA_NAME_VERSION (n1
));
4652 bitmap_set_bit (e2
, SSA_NAME_VERSION (n2
));
4654 /* If the equivalence sets have a common intersection, then the two
4655 names can be compared without checking their ranges. */
4656 if (bitmap_intersect_p (e1
, e2
))
4658 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
4659 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
4661 return (comp
== EQ_EXPR
|| comp
== GE_EXPR
|| comp
== LE_EXPR
)
4663 : boolean_false_node
;
4666 /* Start at -1. Set it to 0 if we do a comparison without relying
4667 on overflow, or 1 if all comparisons rely on overflow. */
4668 used_strict_overflow
= -1;
4670 /* Otherwise, compare all the equivalent ranges. First, add N1 and
4671 N2 to their own set of equivalences to avoid duplicating the body
4672 of the loop just to check N1 and N2 ranges. */
4673 EXECUTE_IF_SET_IN_BITMAP (e1
, 0, i1
, bi1
)
4675 value_range_t vr1
= *(vr_value
[i1
]);
4677 /* If the range is VARYING or UNDEFINED, use the name itself. */
4678 if (vr1
.type
== VR_VARYING
|| vr1
.type
== VR_UNDEFINED
)
4680 vr1
.type
= VR_RANGE
;
4681 vr1
.min
= ssa_name (i1
);
4682 vr1
.max
= ssa_name (i1
);
4685 t
= retval
= NULL_TREE
;
4686 EXECUTE_IF_SET_IN_BITMAP (e2
, 0, i2
, bi2
)
4690 value_range_t vr2
= *(vr_value
[i2
]);
4692 if (vr2
.type
== VR_VARYING
|| vr2
.type
== VR_UNDEFINED
)
4694 vr2
.type
= VR_RANGE
;
4695 vr2
.min
= ssa_name (i2
);
4696 vr2
.max
= ssa_name (i2
);
4699 t
= compare_ranges (comp
, &vr1
, &vr2
, &sop
);
4702 /* If we get different answers from different members
4703 of the equivalence set this check must be in a dead
4704 code region. Folding it to a trap representation
4705 would be correct here. For now just return don't-know. */
4709 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
4710 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
4716 used_strict_overflow
= 0;
4717 else if (used_strict_overflow
< 0)
4718 used_strict_overflow
= 1;
4724 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
4725 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
4726 if (used_strict_overflow
> 0)
4727 *strict_overflow_p
= true;
4732 /* None of the equivalent ranges are useful in computing this
4734 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
4735 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
4740 /* Given a conditional predicate COND, try to determine if COND yields
4741 true or false based on the value ranges of its operands. Return
4742 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
4743 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
4744 NULL if the conditional cannot be evaluated at compile time.
4746 If USE_EQUIV_P is true, the ranges of all the names equivalent with
4747 the operands in COND are used when trying to compute its value.
4748 This is only used during final substitution. During propagation,
4749 we only check the range of each variable and not its equivalents.
4751 Set *STRICT_OVERFLOW_P to indicate whether we relied on an overflow
4752 infinity to produce the result. */
4755 vrp_evaluate_conditional_warnv (tree cond
, bool use_equiv_p
,
4756 bool *strict_overflow_p
)
4758 gcc_assert (TREE_CODE (cond
) == SSA_NAME
4759 || TREE_CODE_CLASS (TREE_CODE (cond
)) == tcc_comparison
);
4761 if (TREE_CODE (cond
) == SSA_NAME
)
4767 retval
= compare_name_with_value (NE_EXPR
, cond
, boolean_false_node
,
4771 value_range_t
*vr
= get_value_range (cond
);
4772 retval
= compare_range_with_value (NE_EXPR
, vr
, boolean_false_node
,
4776 /* If COND has a known boolean range, return it. */
4780 /* Otherwise, if COND has a symbolic range of exactly one value,
4782 vr
= get_value_range (cond
);
4783 if (vr
->type
== VR_RANGE
&& vr
->min
== vr
->max
)
4788 tree op0
= TREE_OPERAND (cond
, 0);
4789 tree op1
= TREE_OPERAND (cond
, 1);
4791 /* We only deal with integral and pointer types. */
4792 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
4793 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
4798 if (TREE_CODE (op0
) == SSA_NAME
&& TREE_CODE (op1
) == SSA_NAME
)
4799 return compare_names (TREE_CODE (cond
), op0
, op1
,
4801 else if (TREE_CODE (op0
) == SSA_NAME
)
4802 return compare_name_with_value (TREE_CODE (cond
), op0
, op1
,
4804 else if (TREE_CODE (op1
) == SSA_NAME
)
4805 return (compare_name_with_value
4806 (swap_tree_comparison (TREE_CODE (cond
)), op1
, op0
,
4807 strict_overflow_p
));
4811 value_range_t
*vr0
, *vr1
;
4813 vr0
= (TREE_CODE (op0
) == SSA_NAME
) ? get_value_range (op0
) : NULL
;
4814 vr1
= (TREE_CODE (op1
) == SSA_NAME
) ? get_value_range (op1
) : NULL
;
4817 return compare_ranges (TREE_CODE (cond
), vr0
, vr1
,
4819 else if (vr0
&& vr1
== NULL
)
4820 return compare_range_with_value (TREE_CODE (cond
), vr0
, op1
,
4822 else if (vr0
== NULL
&& vr1
)
4823 return (compare_range_with_value
4824 (swap_tree_comparison (TREE_CODE (cond
)), vr1
, op0
,
4825 strict_overflow_p
));
4829 /* Anything else cannot be computed statically. */
4833 /* Given COND within STMT, try to simplify it based on value range
4834 information. Return NULL if the conditional can not be evaluated.
4835 The ranges of all the names equivalent with the operands in COND
4836 will be used when trying to compute the value. If the result is
4837 based on undefined signed overflow, issue a warning if
4841 vrp_evaluate_conditional (tree cond
, tree stmt
)
4847 ret
= vrp_evaluate_conditional_warnv (cond
, true, &sop
);
4851 enum warn_strict_overflow_code wc
;
4852 const char* warnmsg
;
4854 if (is_gimple_min_invariant (ret
))
4856 wc
= WARN_STRICT_OVERFLOW_CONDITIONAL
;
4857 warnmsg
= G_("assuming signed overflow does not occur when "
4858 "simplifying conditional to constant");
4862 wc
= WARN_STRICT_OVERFLOW_COMPARISON
;
4863 warnmsg
= G_("assuming signed overflow does not occur when "
4864 "simplifying conditional");
4867 if (issue_strict_overflow_warning (wc
))
4871 if (!EXPR_HAS_LOCATION (stmt
))
4872 locus
= input_location
;
4874 locus
= EXPR_LOCATION (stmt
);
4875 warning (OPT_Wstrict_overflow
, "%H%s", &locus
, warnmsg
);
4883 /* Visit conditional statement STMT. If we can determine which edge
4884 will be taken out of STMT's basic block, record it in
4885 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
4886 SSA_PROP_VARYING. */
4888 static enum ssa_prop_result
4889 vrp_visit_cond_stmt (tree stmt
, edge
*taken_edge_p
)
4894 *taken_edge_p
= NULL
;
4896 /* FIXME. Handle SWITCH_EXPRs. */
4897 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
4898 return SSA_PROP_VARYING
;
4900 cond
= COND_EXPR_COND (stmt
);
4902 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4907 fprintf (dump_file
, "\nVisiting conditional with predicate: ");
4908 print_generic_expr (dump_file
, cond
, 0);
4909 fprintf (dump_file
, "\nWith known ranges\n");
4911 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, i
, SSA_OP_USE
)
4913 fprintf (dump_file
, "\t");
4914 print_generic_expr (dump_file
, use
, 0);
4915 fprintf (dump_file
, ": ");
4916 dump_value_range (dump_file
, vr_value
[SSA_NAME_VERSION (use
)]);
4919 fprintf (dump_file
, "\n");
4922 /* Compute the value of the predicate COND by checking the known
4923 ranges of each of its operands.
4925 Note that we cannot evaluate all the equivalent ranges here
4926 because those ranges may not yet be final and with the current
4927 propagation strategy, we cannot determine when the value ranges
4928 of the names in the equivalence set have changed.
4930 For instance, given the following code fragment
4934 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
4938 Assume that on the first visit to i_14, i_5 has the temporary
4939 range [8, 8] because the second argument to the PHI function is
4940 not yet executable. We derive the range ~[0, 0] for i_14 and the
4941 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
4942 the first time, since i_14 is equivalent to the range [8, 8], we
4943 determine that the predicate is always false.
4945 On the next round of propagation, i_13 is determined to be
4946 VARYING, which causes i_5 to drop down to VARYING. So, another
4947 visit to i_14 is scheduled. In this second visit, we compute the
4948 exact same range and equivalence set for i_14, namely ~[0, 0] and
4949 { i_5 }. But we did not have the previous range for i_5
4950 registered, so vrp_visit_assignment thinks that the range for
4951 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
4952 is not visited again, which stops propagation from visiting
4953 statements in the THEN clause of that if().
4955 To properly fix this we would need to keep the previous range
4956 value for the names in the equivalence set. This way we would've
4957 discovered that from one visit to the other i_5 changed from
4958 range [8, 8] to VR_VARYING.
4960 However, fixing this apparent limitation may not be worth the
4961 additional checking. Testing on several code bases (GCC, DLV,
4962 MICO, TRAMP3D and SPEC2000) showed that doing this results in
4963 4 more predicates folded in SPEC. */
4965 val
= vrp_evaluate_conditional_warnv (cond
, false, &sop
);
4969 *taken_edge_p
= find_taken_edge (bb_for_stmt (stmt
), val
);
4972 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4974 "\nIgnoring predicate evaluation because "
4975 "it assumes that signed overflow is undefined");
4980 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4982 fprintf (dump_file
, "\nPredicate evaluates to: ");
4983 if (val
== NULL_TREE
)
4984 fprintf (dump_file
, "DON'T KNOW\n");
4986 print_generic_stmt (dump_file
, val
, 0);
4989 return (*taken_edge_p
) ? SSA_PROP_INTERESTING
: SSA_PROP_VARYING
;
4993 /* Evaluate statement STMT. If the statement produces a useful range,
4994 return SSA_PROP_INTERESTING and record the SSA name with the
4995 interesting range into *OUTPUT_P.
4997 If STMT is a conditional branch and we can determine its truth
4998 value, the taken edge is recorded in *TAKEN_EDGE_P.
5000 If STMT produces a varying value, return SSA_PROP_VARYING. */
5002 static enum ssa_prop_result
5003 vrp_visit_stmt (tree stmt
, edge
*taken_edge_p
, tree
*output_p
)
5009 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5011 fprintf (dump_file
, "\nVisiting statement:\n");
5012 print_generic_stmt (dump_file
, stmt
, dump_flags
);
5013 fprintf (dump_file
, "\n");
5016 ann
= stmt_ann (stmt
);
5017 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
5019 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
5021 /* In general, assignments with virtual operands are not useful
5022 for deriving ranges, with the obvious exception of calls to
5023 builtin functions. */
5024 if ((TREE_CODE (rhs
) == CALL_EXPR
5025 && TREE_CODE (CALL_EXPR_FN (rhs
)) == ADDR_EXPR
5026 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs
), 0))
5027 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs
), 0)))
5028 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
5029 return vrp_visit_assignment (stmt
, output_p
);
5031 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
5032 return vrp_visit_cond_stmt (stmt
, taken_edge_p
);
5034 /* All other statements produce nothing of interest for VRP, so mark
5035 their outputs varying and prevent further simulation. */
5036 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
5037 set_value_range_to_varying (get_value_range (def
));
5039 return SSA_PROP_VARYING
;
5043 /* Meet operation for value ranges. Given two value ranges VR0 and
5044 VR1, store in VR0 a range that contains both VR0 and VR1. This
5045 may not be the smallest possible such range. */
5048 vrp_meet (value_range_t
*vr0
, value_range_t
*vr1
)
5050 if (vr0
->type
== VR_UNDEFINED
)
5052 copy_value_range (vr0
, vr1
);
5056 if (vr1
->type
== VR_UNDEFINED
)
5058 /* Nothing to do. VR0 already has the resulting range. */
5062 if (vr0
->type
== VR_VARYING
)
5064 /* Nothing to do. VR0 already has the resulting range. */
5068 if (vr1
->type
== VR_VARYING
)
5070 set_value_range_to_varying (vr0
);
5074 if (vr0
->type
== VR_RANGE
&& vr1
->type
== VR_RANGE
)
5079 /* Compute the convex hull of the ranges. The lower limit of
5080 the new range is the minimum of the two ranges. If they
5081 cannot be compared, then give up. */
5082 cmp
= compare_values (vr0
->min
, vr1
->min
);
5083 if (cmp
== 0 || cmp
== 1)
5090 /* Similarly, the upper limit of the new range is the maximum
5091 of the two ranges. If they cannot be compared, then
5093 cmp
= compare_values (vr0
->max
, vr1
->max
);
5094 if (cmp
== 0 || cmp
== -1)
5101 /* The resulting set of equivalences is the intersection of
5103 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
5104 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
5105 else if (vr0
->equiv
&& !vr1
->equiv
)
5106 bitmap_clear (vr0
->equiv
);
5108 set_value_range (vr0
, vr0
->type
, min
, max
, vr0
->equiv
);
5110 else if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
5112 /* Two anti-ranges meet only if their complements intersect.
5113 Only handle the case of identical ranges. */
5114 if (compare_values (vr0
->min
, vr1
->min
) == 0
5115 && compare_values (vr0
->max
, vr1
->max
) == 0
5116 && compare_values (vr0
->min
, vr0
->max
) == 0)
5118 /* The resulting set of equivalences is the intersection of
5120 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
5121 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
5122 else if (vr0
->equiv
&& !vr1
->equiv
)
5123 bitmap_clear (vr0
->equiv
);
5128 else if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
5130 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
5131 only handle the case where the ranges have an empty intersection.
5132 The result of the meet operation is the anti-range. */
5133 if (!symbolic_range_p (vr0
)
5134 && !symbolic_range_p (vr1
)
5135 && !value_ranges_intersect_p (vr0
, vr1
))
5137 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
5138 set. We need to compute the intersection of the two
5139 equivalence sets. */
5140 if (vr1
->type
== VR_ANTI_RANGE
)
5141 set_value_range (vr0
, vr1
->type
, vr1
->min
, vr1
->max
, vr0
->equiv
);
5143 /* The resulting set of equivalences is the intersection of
5145 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
5146 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
5147 else if (vr0
->equiv
&& !vr1
->equiv
)
5148 bitmap_clear (vr0
->equiv
);
5159 /* Failed to find an efficient meet. Before giving up and setting
5160 the result to VARYING, see if we can at least derive a useful
5161 anti-range. FIXME, all this nonsense about distinguishing
5162 anti-ranges from ranges is necessary because of the odd
5163 semantics of range_includes_zero_p and friends. */
5164 if (!symbolic_range_p (vr0
)
5165 && ((vr0
->type
== VR_RANGE
&& !range_includes_zero_p (vr0
))
5166 || (vr0
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr0
)))
5167 && !symbolic_range_p (vr1
)
5168 && ((vr1
->type
== VR_RANGE
&& !range_includes_zero_p (vr1
))
5169 || (vr1
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr1
))))
5171 set_value_range_to_nonnull (vr0
, TREE_TYPE (vr0
->min
));
5173 /* Since this meet operation did not result from the meeting of
5174 two equivalent names, VR0 cannot have any equivalences. */
5176 bitmap_clear (vr0
->equiv
);
5179 set_value_range_to_varying (vr0
);
5183 /* Visit all arguments for PHI node PHI that flow through executable
5184 edges. If a valid value range can be derived from all the incoming
5185 value ranges, set a new range for the LHS of PHI. */
5187 static enum ssa_prop_result
5188 vrp_visit_phi_node (tree phi
)
5191 tree lhs
= PHI_RESULT (phi
);
5192 value_range_t
*lhs_vr
= get_value_range (lhs
);
5193 value_range_t vr_result
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
5194 int edges
, old_edges
;
5196 copy_value_range (&vr_result
, lhs_vr
);
5198 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5200 fprintf (dump_file
, "\nVisiting PHI node: ");
5201 print_generic_expr (dump_file
, phi
, dump_flags
);
5205 for (i
= 0; i
< PHI_NUM_ARGS (phi
); i
++)
5207 edge e
= PHI_ARG_EDGE (phi
, i
);
5209 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5212 "\n Argument #%d (%d -> %d %sexecutable)\n",
5213 i
, e
->src
->index
, e
->dest
->index
,
5214 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
5217 if (e
->flags
& EDGE_EXECUTABLE
)
5219 tree arg
= PHI_ARG_DEF (phi
, i
);
5220 value_range_t vr_arg
;
5224 if (TREE_CODE (arg
) == SSA_NAME
)
5226 vr_arg
= *(get_value_range (arg
));
5230 vr_arg
.type
= VR_RANGE
;
5233 vr_arg
.equiv
= NULL
;
5236 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5238 fprintf (dump_file
, "\t");
5239 print_generic_expr (dump_file
, arg
, dump_flags
);
5240 fprintf (dump_file
, "\n\tValue: ");
5241 dump_value_range (dump_file
, &vr_arg
);
5242 fprintf (dump_file
, "\n");
5245 vrp_meet (&vr_result
, &vr_arg
);
5247 if (vr_result
.type
== VR_VARYING
)
5252 if (vr_result
.type
== VR_VARYING
)
5255 old_edges
= vr_phi_edge_counts
[SSA_NAME_VERSION (lhs
)];
5256 vr_phi_edge_counts
[SSA_NAME_VERSION (lhs
)] = edges
;
5258 /* To prevent infinite iterations in the algorithm, derive ranges
5259 when the new value is slightly bigger or smaller than the
5260 previous one. We don't do this if we have seen a new executable
5261 edge; this helps us avoid an overflow infinity for conditionals
5262 which are not in a loop. */
5263 if (lhs_vr
->type
== VR_RANGE
&& vr_result
.type
== VR_RANGE
5264 && edges
<= old_edges
)
5266 if (!POINTER_TYPE_P (TREE_TYPE (lhs
)))
5268 int cmp_min
= compare_values (lhs_vr
->min
, vr_result
.min
);
5269 int cmp_max
= compare_values (lhs_vr
->max
, vr_result
.max
);
5271 /* If the new minimum is smaller or larger than the previous
5272 one, go all the way to -INF. In the first case, to avoid
5273 iterating millions of times to reach -INF, and in the
5274 other case to avoid infinite bouncing between different
5276 if (cmp_min
> 0 || cmp_min
< 0)
5278 /* If we will end up with a (-INF, +INF) range, set it
5280 if (is_positive_overflow_infinity (vr_result
.max
)
5282 == TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
))))
5285 if (!needs_overflow_infinity (TREE_TYPE (vr_result
.min
)))
5286 vr_result
.min
= TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
));
5287 else if (supports_overflow_infinity (TREE_TYPE (vr_result
.min
)))
5289 negative_overflow_infinity (TREE_TYPE (vr_result
.min
));
5294 /* Similarly, if the new maximum is smaller or larger than
5295 the previous one, go all the way to +INF. */
5296 if (cmp_max
< 0 || cmp_max
> 0)
5298 /* If we will end up with a (-INF, +INF) range, set it
5300 if (is_negative_overflow_infinity (vr_result
.min
)
5302 == TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
))))
5305 if (!needs_overflow_infinity (TREE_TYPE (vr_result
.max
)))
5306 vr_result
.max
= TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
));
5307 else if (supports_overflow_infinity (TREE_TYPE (vr_result
.max
)))
5309 positive_overflow_infinity (TREE_TYPE (vr_result
.max
));
5316 /* If the new range is different than the previous value, keep
5318 if (update_value_range (lhs
, &vr_result
))
5319 return SSA_PROP_INTERESTING
;
5321 /* Nothing changed, don't add outgoing edges. */
5322 return SSA_PROP_NOT_INTERESTING
;
5324 /* No match found. Set the LHS to VARYING. */
5326 set_value_range_to_varying (lhs_vr
);
5327 return SSA_PROP_VARYING
;
5330 /* Simplify a division or modulo operator to a right shift or
5331 bitwise and if the first operand is unsigned or is greater
5332 than zero and the second operand is an exact power of two. */
5335 simplify_div_or_mod_using_ranges (tree stmt
, tree rhs
, enum tree_code rhs_code
)
5338 tree op
= TREE_OPERAND (rhs
, 0);
5339 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
5341 if (TYPE_UNSIGNED (TREE_TYPE (op
)))
5343 val
= integer_one_node
;
5349 val
= compare_range_with_value (GT_EXPR
, vr
, integer_zero_node
, &sop
);
5353 && integer_onep (val
)
5354 && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC
))
5358 if (!EXPR_HAS_LOCATION (stmt
))
5359 locus
= input_location
;
5361 locus
= EXPR_LOCATION (stmt
);
5362 warning (OPT_Wstrict_overflow
,
5363 ("%Hassuming signed overflow does not occur when "
5364 "simplifying / or %% to >> or &"),
5369 if (val
&& integer_onep (val
))
5372 tree op0
= TREE_OPERAND (rhs
, 0);
5373 tree op1
= TREE_OPERAND (rhs
, 1);
5375 if (rhs_code
== TRUNC_DIV_EXPR
)
5377 t
= build_int_cst (NULL_TREE
, tree_log2 (op1
));
5378 t
= build2 (RSHIFT_EXPR
, TREE_TYPE (op0
), op0
, t
);
5382 t
= build_int_cst (TREE_TYPE (op1
), 1);
5383 t
= int_const_binop (MINUS_EXPR
, op1
, t
, 0);
5384 t
= fold_convert (TREE_TYPE (op0
), t
);
5385 t
= build2 (BIT_AND_EXPR
, TREE_TYPE (op0
), op0
, t
);
5388 GIMPLE_STMT_OPERAND (stmt
, 1) = t
;
5393 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
5394 ABS_EXPR. If the operand is <= 0, then simplify the
5395 ABS_EXPR into a NEGATE_EXPR. */
5398 simplify_abs_using_ranges (tree stmt
, tree rhs
)
5401 tree op
= TREE_OPERAND (rhs
, 0);
5402 tree type
= TREE_TYPE (op
);
5403 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
5405 if (TYPE_UNSIGNED (type
))
5407 val
= integer_zero_node
;
5413 val
= compare_range_with_value (LE_EXPR
, vr
, integer_zero_node
, &sop
);
5417 val
= compare_range_with_value (GE_EXPR
, vr
, integer_zero_node
,
5422 if (integer_zerop (val
))
5423 val
= integer_one_node
;
5424 else if (integer_onep (val
))
5425 val
= integer_zero_node
;
5430 && (integer_onep (val
) || integer_zerop (val
)))
5434 if (sop
&& issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC
))
5438 if (!EXPR_HAS_LOCATION (stmt
))
5439 locus
= input_location
;
5441 locus
= EXPR_LOCATION (stmt
);
5442 warning (OPT_Wstrict_overflow
,
5443 ("%Hassuming signed overflow does not occur when "
5444 "simplifying abs (X) to X or -X"),
5448 if (integer_onep (val
))
5449 t
= build1 (NEGATE_EXPR
, TREE_TYPE (op
), op
);
5453 GIMPLE_STMT_OPERAND (stmt
, 1) = t
;
5459 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
5460 a known value range VR.
5462 If there is one and only one value which will satisfy the
5463 conditional, then return that value. Else return NULL. */
5466 test_for_singularity (enum tree_code cond_code
, tree op0
,
5467 tree op1
, value_range_t
*vr
)
5472 /* Extract minimum/maximum values which satisfy the
5473 the conditional as it was written. */
5474 if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
5476 /* This should not be negative infinity; there is no overflow
5478 min
= TYPE_MIN_VALUE (TREE_TYPE (op0
));
5481 if (cond_code
== LT_EXPR
&& !is_overflow_infinity (max
))
5483 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
5484 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (op0
), max
, one
);
5487 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
5489 /* This should not be positive infinity; there is no overflow
5491 max
= TYPE_MAX_VALUE (TREE_TYPE (op0
));
5494 if (cond_code
== GT_EXPR
&& !is_overflow_infinity (min
))
5496 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
5497 min
= fold_build2 (PLUS_EXPR
, TREE_TYPE (op0
), min
, one
);
5501 /* Now refine the minimum and maximum values using any
5502 value range information we have for op0. */
5505 if (compare_values (vr
->min
, min
) == -1)
5509 if (compare_values (vr
->max
, max
) == 1)
5514 /* If the new min/max values have converged to a single value,
5515 then there is only one value which can satisfy the condition,
5516 return that value. */
5517 if (operand_equal_p (min
, max
, 0) && is_gimple_min_invariant (min
))
5523 /* Simplify a conditional using a relational operator to an equality
5524 test if the range information indicates only one value can satisfy
5525 the original conditional. */
5528 simplify_cond_using_ranges (tree stmt
)
5530 tree cond
= COND_EXPR_COND (stmt
);
5531 tree op0
= TREE_OPERAND (cond
, 0);
5532 tree op1
= TREE_OPERAND (cond
, 1);
5533 enum tree_code cond_code
= TREE_CODE (cond
);
5535 if (cond_code
!= NE_EXPR
5536 && cond_code
!= EQ_EXPR
5537 && TREE_CODE (op0
) == SSA_NAME
5538 && INTEGRAL_TYPE_P (TREE_TYPE (op0
))
5539 && is_gimple_min_invariant (op1
))
5541 value_range_t
*vr
= get_value_range (op0
);
5543 /* If we have range information for OP0, then we might be
5544 able to simplify this conditional. */
5545 if (vr
->type
== VR_RANGE
)
5547 tree
new = test_for_singularity (cond_code
, op0
, op1
, vr
);
5553 fprintf (dump_file
, "Simplified relational ");
5554 print_generic_expr (dump_file
, cond
, 0);
5555 fprintf (dump_file
, " into ");
5558 COND_EXPR_COND (stmt
)
5559 = build2 (EQ_EXPR
, boolean_type_node
, op0
, new);
5564 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
5565 fprintf (dump_file
, "\n");
5571 /* Try again after inverting the condition. We only deal
5572 with integral types here, so no need to worry about
5573 issues with inverting FP comparisons. */
5574 cond_code
= invert_tree_comparison (cond_code
, false);
5575 new = test_for_singularity (cond_code
, op0
, op1
, vr
);
5581 fprintf (dump_file
, "Simplified relational ");
5582 print_generic_expr (dump_file
, cond
, 0);
5583 fprintf (dump_file
, " into ");
5586 COND_EXPR_COND (stmt
)
5587 = build2 (NE_EXPR
, boolean_type_node
, op0
, new);
5592 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
5593 fprintf (dump_file
, "\n");
5602 /* Simplify STMT using ranges if possible. */
5605 simplify_stmt_using_ranges (tree stmt
)
5607 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
5609 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
5610 enum tree_code rhs_code
= TREE_CODE (rhs
);
5612 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
5613 and BIT_AND_EXPR respectively if the first operand is greater
5614 than zero and the second operand is an exact power of two. */
5615 if ((rhs_code
== TRUNC_DIV_EXPR
|| rhs_code
== TRUNC_MOD_EXPR
)
5616 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0)))
5617 && integer_pow2p (TREE_OPERAND (rhs
, 1)))
5618 simplify_div_or_mod_using_ranges (stmt
, rhs
, rhs_code
);
5620 /* Transform ABS (X) into X or -X as appropriate. */
5621 if (rhs_code
== ABS_EXPR
5622 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == SSA_NAME
5623 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0))))
5624 simplify_abs_using_ranges (stmt
, rhs
);
5626 else if (TREE_CODE (stmt
) == COND_EXPR
5627 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt
)))
5629 simplify_cond_using_ranges (stmt
);
5633 /* Stack of dest,src equivalency pairs that need to be restored after
5634 each attempt to thread a block's incoming edge to an outgoing edge.
5636 A NULL entry is used to mark the end of pairs which need to be
5638 static VEC(tree
,heap
) *stack
;
5640 /* A trivial wrapper so that we can present the generic jump threading
5641 code with a simple API for simplifying statements. STMT is the
5642 statement we want to simplify, WITHIN_STMT provides the location
5643 for any overflow warnings. */
5646 simplify_stmt_for_jump_threading (tree stmt
, tree within_stmt
)
5648 /* We only use VRP information to simplify conditionals. This is
5649 overly conservative, but it's unclear if doing more would be
5650 worth the compile time cost. */
5651 if (TREE_CODE (stmt
) != COND_EXPR
)
5654 return vrp_evaluate_conditional (COND_EXPR_COND (stmt
), within_stmt
);
5657 /* Blocks which have more than one predecessor and more than
5658 one successor present jump threading opportunities. ie,
5659 when the block is reached from a specific predecessor, we
5660 may be able to determine which of the outgoing edges will
5661 be traversed. When this optimization applies, we are able
5662 to avoid conditionals at runtime and we may expose secondary
5663 optimization opportunities.
5665 This routine is effectively a driver for the generic jump
5666 threading code. It basically just presents the generic code
5667 with edges that may be suitable for jump threading.
5669 Unlike DOM, we do not iterate VRP if jump threading was successful.
5670 While iterating may expose new opportunities for VRP, it is expected
5671 those opportunities would be very limited and the compile time cost
5672 to expose those opportunities would be significant.
5674 As jump threading opportunities are discovered, they are registered
5675 for later realization. */
5678 identify_jump_threads (void)
5683 /* Ugh. When substituting values earlier in this pass we can
5684 wipe the dominance information. So rebuild the dominator
5685 information as we need it within the jump threading code. */
5686 calculate_dominance_info (CDI_DOMINATORS
);
5688 /* We do not allow VRP information to be used for jump threading
5689 across a back edge in the CFG. Otherwise it becomes too
5690 difficult to avoid eliminating loop exit tests. Of course
5691 EDGE_DFS_BACK is not accurate at this time so we have to
5693 mark_dfs_back_edges ();
5695 /* Allocate our unwinder stack to unwind any temporary equivalences
5696 that might be recorded. */
5697 stack
= VEC_alloc (tree
, heap
, 20);
5699 /* To avoid lots of silly node creation, we create a single
5700 conditional and just modify it in-place when attempting to
5702 dummy
= build2 (EQ_EXPR
, boolean_type_node
, NULL
, NULL
);
5703 dummy
= build3 (COND_EXPR
, void_type_node
, dummy
, NULL
, NULL
);
5705 /* Walk through all the blocks finding those which present a
5706 potential jump threading opportunity. We could set this up
5707 as a dominator walker and record data during the walk, but
5708 I doubt it's worth the effort for the classes of jump
5709 threading opportunities we are trying to identify at this
5710 point in compilation. */
5715 /* If the generic jump threading code does not find this block
5716 interesting, then there is nothing to do. */
5717 if (! potentially_threadable_block (bb
))
5720 /* We only care about blocks ending in a COND_EXPR. While there
5721 may be some value in handling SWITCH_EXPR here, I doubt it's
5722 terribly important. */
5723 last
= bsi_stmt (bsi_last (bb
));
5724 if (TREE_CODE (last
) != COND_EXPR
)
5727 /* We're basically looking for any kind of conditional with
5728 integral type arguments. */
5729 cond
= COND_EXPR_COND (last
);
5730 if ((TREE_CODE (cond
) == SSA_NAME
5731 && INTEGRAL_TYPE_P (TREE_TYPE (cond
)))
5732 || (COMPARISON_CLASS_P (cond
)
5733 && TREE_CODE (TREE_OPERAND (cond
, 0)) == SSA_NAME
5734 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond
, 0)))
5735 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == SSA_NAME
5736 || is_gimple_min_invariant (TREE_OPERAND (cond
, 1)))
5737 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond
, 1)))))
5742 /* We've got a block with multiple predecessors and multiple
5743 successors which also ends in a suitable conditional. For
5744 each predecessor, see if we can thread it to a specific
5746 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
5748 /* Do not thread across back edges or abnormal edges
5750 if (e
->flags
& (EDGE_DFS_BACK
| EDGE_COMPLEX
))
5753 thread_across_edge (dummy
, e
, true,
5755 simplify_stmt_for_jump_threading
);
5760 /* We do not actually update the CFG or SSA graphs at this point as
5761 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
5762 handle ASSERT_EXPRs gracefully. */
5765 /* We identified all the jump threading opportunities earlier, but could
5766 not transform the CFG at that time. This routine transforms the
5767 CFG and arranges for the dominator tree to be rebuilt if necessary.
5769 Note the SSA graph update will occur during the normal TODO
5770 processing by the pass manager. */
5772 finalize_jump_threads (void)
5774 bool cfg_altered
= false;
5775 cfg_altered
= thread_through_all_blocks ();
5777 /* If we threaded jumps, then we need to recompute the dominance
5780 free_dominance_info (CDI_DOMINATORS
);
5781 VEC_free (tree
, heap
, stack
);
5785 /* Traverse all the blocks folding conditionals with known ranges. */
5791 prop_value_t
*single_val_range
;
5792 bool do_value_subst_p
;
5796 fprintf (dump_file
, "\nValue ranges after VRP:\n\n");
5797 dump_all_value_ranges (dump_file
);
5798 fprintf (dump_file
, "\n");
5801 /* We may have ended with ranges that have exactly one value. Those
5802 values can be substituted as any other copy/const propagated
5803 value using substitute_and_fold. */
5804 single_val_range
= XCNEWVEC (prop_value_t
, num_ssa_names
);
5806 do_value_subst_p
= false;
5807 for (i
= 0; i
< num_ssa_names
; i
++)
5809 && vr_value
[i
]->type
== VR_RANGE
5810 && vr_value
[i
]->min
== vr_value
[i
]->max
)
5812 single_val_range
[i
].value
= vr_value
[i
]->min
;
5813 do_value_subst_p
= true;
5816 if (!do_value_subst_p
)
5818 /* We found no single-valued ranges, don't waste time trying to
5819 do single value substitution in substitute_and_fold. */
5820 free (single_val_range
);
5821 single_val_range
= NULL
;
5824 substitute_and_fold (single_val_range
, true);
5826 if (warn_array_bounds
)
5827 check_all_array_refs ();
5829 /* We must identify jump threading opportunities before we release
5830 the datastructures built by VRP. */
5831 identify_jump_threads ();
5833 /* Free allocated memory. */
5834 for (i
= 0; i
< num_ssa_names
; i
++)
5837 BITMAP_FREE (vr_value
[i
]->equiv
);
5841 free (single_val_range
);
5843 free (vr_phi_edge_counts
);
5845 /* So that we can distinguish between VRP data being available
5846 and not available. */
5848 vr_phi_edge_counts
= NULL
;
5852 /* Main entry point to VRP (Value Range Propagation). This pass is
5853 loosely based on J. R. C. Patterson, ``Accurate Static Branch
5854 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
5855 Programming Language Design and Implementation, pp. 67-78, 1995.
5856 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
5858 This is essentially an SSA-CCP pass modified to deal with ranges
5859 instead of constants.
5861 While propagating ranges, we may find that two or more SSA name
5862 have equivalent, though distinct ranges. For instance,
5865 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
5867 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
5871 In the code above, pointer p_5 has range [q_2, q_2], but from the
5872 code we can also determine that p_5 cannot be NULL and, if q_2 had
5873 a non-varying range, p_5's range should also be compatible with it.
5875 These equivalences are created by two expressions: ASSERT_EXPR and
5876 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
5877 result of another assertion, then we can use the fact that p_5 and
5878 p_4 are equivalent when evaluating p_5's range.
5880 Together with value ranges, we also propagate these equivalences
5881 between names so that we can take advantage of information from
5882 multiple ranges when doing final replacement. Note that this
5883 equivalency relation is transitive but not symmetric.
5885 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
5886 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
5887 in contexts where that assertion does not hold (e.g., in line 6).
5889 TODO, the main difference between this pass and Patterson's is that
5890 we do not propagate edge probabilities. We only compute whether
5891 edges can be taken or not. That is, instead of having a spectrum
5892 of jump probabilities between 0 and 1, we only deal with 0, 1 and
5893 DON'T KNOW. In the future, it may be worthwhile to propagate
5894 probabilities to aid branch prediction. */
5899 insert_range_assertions ();
5901 loop_optimizer_init (LOOPS_NORMAL
);
5906 ssa_propagate (vrp_visit_stmt
, vrp_visit_phi_node
);
5912 loop_optimizer_finalize ();
5915 /* ASSERT_EXPRs must be removed before finalizing jump threads
5916 as finalizing jump threads calls the CFG cleanup code which
5917 does not properly handle ASSERT_EXPRs. */
5918 remove_range_assertions ();
5920 /* If we exposed any new variables, go ahead and put them into
5921 SSA form now, before we handle jump threading. This simplifies
5922 interactions between rewriting of _DECL nodes into SSA form
5923 and rewriting SSA_NAME nodes into SSA form after block
5924 duplication and CFG manipulation. */
5925 update_ssa (TODO_update_ssa
);
5927 finalize_jump_threads ();
5934 return flag_tree_vrp
!= 0;
5937 struct tree_opt_pass pass_vrp
=
5940 gate_vrp
, /* gate */
5941 execute_vrp
, /* execute */
5944 0, /* static_pass_number */
5945 TV_TREE_VRP
, /* tv_id */
5946 PROP_ssa
| PROP_alias
, /* properties_required */
5947 0, /* properties_provided */
5948 0, /* properties_destroyed */
5949 0, /* todo_flags_start */
5954 | TODO_update_ssa
, /* todo_flags_finish */