1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
24 #include "coretypes.h"
29 #include "basic-block.h"
30 #include "tree-flow.h"
31 #include "tree-pass.h"
32 #include "tree-dump.h"
34 #include "diagnostic.h"
38 #include "tree-scalar-evolution.h"
39 #include "tree-ssa-propagate.h"
40 #include "tree-chrec.h"
42 /* Set of SSA names found during the dominator traversal of a
43 sub-graph in find_assert_locations. */
44 static sbitmap found_in_subgraph
;
46 /* Local functions. */
47 static int compare_values (tree val1
, tree val2
);
48 static int compare_values_warnv (tree val1
, tree val2
, bool *);
49 static void vrp_meet (value_range_t
*, value_range_t
*);
50 static tree
vrp_evaluate_conditional_warnv (tree
, bool, bool *);
52 /* Location information for ASSERT_EXPRs. Each instance of this
53 structure describes an ASSERT_EXPR for an SSA name. Since a single
54 SSA name may have more than one assertion associated with it, these
55 locations are kept in a linked list attached to the corresponding
59 /* Basic block where the assertion would be inserted. */
62 /* Some assertions need to be inserted on an edge (e.g., assertions
63 generated by COND_EXPRs). In those cases, BB will be NULL. */
66 /* Pointer to the statement that generated this assertion. */
67 block_stmt_iterator si
;
69 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
70 enum tree_code comp_code
;
72 /* Value being compared against. */
75 /* Next node in the linked list. */
76 struct assert_locus_d
*next
;
79 typedef struct assert_locus_d
*assert_locus_t
;
81 /* If bit I is present, it means that SSA name N_i has a list of
82 assertions that should be inserted in the IL. */
83 static bitmap need_assert_for
;
85 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
86 holds a list of ASSERT_LOCUS_T nodes that describe where
87 ASSERT_EXPRs for SSA name N_I should be inserted. */
88 static assert_locus_t
*asserts_for
;
90 /* Set of blocks visited in find_assert_locations. Used to avoid
91 visiting the same block more than once. */
92 static sbitmap blocks_visited
;
94 /* Value range array. After propagation, VR_VALUE[I] holds the range
95 of values that SSA name N_I may take. */
96 static value_range_t
**vr_value
;
98 /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the
99 number of executable edges we saw the last time we visited the
101 static int *vr_phi_edge_counts
;
104 /* Return whether TYPE should use an overflow infinity distinct from
105 TYPE_{MIN,MAX}_VALUE. We use an overflow infinity value to
106 represent a signed overflow during VRP computations. An infinity
107 is distinct from a half-range, which will go from some number to
108 TYPE_{MIN,MAX}_VALUE. */
111 needs_overflow_infinity (tree type
)
113 return INTEGRAL_TYPE_P (type
) && !TYPE_OVERFLOW_WRAPS (type
);
116 /* Return whether TYPE can support our overflow infinity
117 representation: we use the TREE_OVERFLOW flag, which only exists
118 for constants. If TYPE doesn't support this, we don't optimize
119 cases which would require signed overflow--we drop them to
123 supports_overflow_infinity (tree type
)
125 #ifdef ENABLE_CHECKING
126 gcc_assert (needs_overflow_infinity (type
));
128 return (TYPE_MIN_VALUE (type
) != NULL_TREE
129 && CONSTANT_CLASS_P (TYPE_MIN_VALUE (type
))
130 && TYPE_MAX_VALUE (type
) != NULL_TREE
131 && CONSTANT_CLASS_P (TYPE_MAX_VALUE (type
)));
134 /* VAL is the maximum or minimum value of a type. Return a
135 corresponding overflow infinity. */
138 make_overflow_infinity (tree val
)
140 #ifdef ENABLE_CHECKING
141 gcc_assert (val
!= NULL_TREE
&& CONSTANT_CLASS_P (val
));
143 val
= copy_node (val
);
144 TREE_OVERFLOW (val
) = 1;
148 /* Return a negative overflow infinity for TYPE. */
151 negative_overflow_infinity (tree type
)
153 #ifdef ENABLE_CHECKING
154 gcc_assert (supports_overflow_infinity (type
));
156 return make_overflow_infinity (TYPE_MIN_VALUE (type
));
159 /* Return a positive overflow infinity for TYPE. */
162 positive_overflow_infinity (tree type
)
164 #ifdef ENABLE_CHECKING
165 gcc_assert (supports_overflow_infinity (type
));
167 return make_overflow_infinity (TYPE_MAX_VALUE (type
));
170 /* Return whether VAL is a negative overflow infinity. */
173 is_negative_overflow_infinity (tree val
)
175 return (needs_overflow_infinity (TREE_TYPE (val
))
176 && CONSTANT_CLASS_P (val
)
177 && TREE_OVERFLOW (val
)
178 && operand_equal_p (val
, TYPE_MIN_VALUE (TREE_TYPE (val
)), 0));
181 /* Return whether VAL is a positive overflow infinity. */
184 is_positive_overflow_infinity (tree val
)
186 return (needs_overflow_infinity (TREE_TYPE (val
))
187 && CONSTANT_CLASS_P (val
)
188 && TREE_OVERFLOW (val
)
189 && operand_equal_p (val
, TYPE_MAX_VALUE (TREE_TYPE (val
)), 0));
192 /* Return whether VAL is a positive or negative overflow infinity. */
195 is_overflow_infinity (tree val
)
197 return (needs_overflow_infinity (TREE_TYPE (val
))
198 && CONSTANT_CLASS_P (val
)
199 && TREE_OVERFLOW (val
)
200 && (operand_equal_p (val
, TYPE_MAX_VALUE (TREE_TYPE (val
)), 0)
201 || operand_equal_p (val
, TYPE_MIN_VALUE (TREE_TYPE (val
)), 0)));
204 /* If VAL is now an overflow infinity, return VAL. Otherwise, return
205 the same value with TREE_OVERFLOW clear. This can be used to avoid
206 confusing a regular value with an overflow value. */
209 avoid_overflow_infinity (tree val
)
211 if (!is_overflow_infinity (val
))
214 if (operand_equal_p (val
, TYPE_MAX_VALUE (TREE_TYPE (val
)), 0))
215 return TYPE_MAX_VALUE (TREE_TYPE (val
));
218 #ifdef ENABLE_CHECKING
219 gcc_assert (operand_equal_p (val
, TYPE_MIN_VALUE (TREE_TYPE (val
)), 0));
221 return TYPE_MIN_VALUE (TREE_TYPE (val
));
226 /* Return whether VAL is equal to the maximum value of its type. This
227 will be true for a positive overflow infinity. We can't do a
228 simple equality comparison with TYPE_MAX_VALUE because C typedefs
229 and Ada subtypes can produce types whose TYPE_MAX_VALUE is not ==
230 to the integer constant with the same value in the type. */
233 vrp_val_is_max (tree val
)
235 tree type_max
= TYPE_MAX_VALUE (TREE_TYPE (val
));
237 return (val
== type_max
238 || (type_max
!= NULL_TREE
239 && operand_equal_p (val
, type_max
, 0)));
242 /* Return whether VAL is equal to the minimum value of its type. This
243 will be true for a negative overflow infinity. */
246 vrp_val_is_min (tree val
)
248 tree type_min
= TYPE_MIN_VALUE (TREE_TYPE (val
));
250 return (val
== type_min
251 || (type_min
!= NULL_TREE
252 && operand_equal_p (val
, type_min
, 0)));
256 /* Return true if ARG is marked with the nonnull attribute in the
257 current function signature. */
260 nonnull_arg_p (tree arg
)
262 tree t
, attrs
, fntype
;
263 unsigned HOST_WIDE_INT arg_num
;
265 gcc_assert (TREE_CODE (arg
) == PARM_DECL
&& POINTER_TYPE_P (TREE_TYPE (arg
)));
267 /* The static chain decl is always non null. */
268 if (arg
== cfun
->static_chain_decl
)
271 fntype
= TREE_TYPE (current_function_decl
);
272 attrs
= lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype
));
274 /* If "nonnull" wasn't specified, we know nothing about the argument. */
275 if (attrs
== NULL_TREE
)
278 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
279 if (TREE_VALUE (attrs
) == NULL_TREE
)
282 /* Get the position number for ARG in the function signature. */
283 for (arg_num
= 1, t
= DECL_ARGUMENTS (current_function_decl
);
285 t
= TREE_CHAIN (t
), arg_num
++)
291 gcc_assert (t
== arg
);
293 /* Now see if ARG_NUM is mentioned in the nonnull list. */
294 for (t
= TREE_VALUE (attrs
); t
; t
= TREE_CHAIN (t
))
296 if (compare_tree_int (TREE_VALUE (t
), arg_num
) == 0)
304 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
307 set_value_range (value_range_t
*vr
, enum value_range_type t
, tree min
,
308 tree max
, bitmap equiv
)
310 #if defined ENABLE_CHECKING
311 /* Check the validity of the range. */
312 if (t
== VR_RANGE
|| t
== VR_ANTI_RANGE
)
316 gcc_assert (min
&& max
);
318 if (INTEGRAL_TYPE_P (TREE_TYPE (min
)) && t
== VR_ANTI_RANGE
)
319 gcc_assert (!vrp_val_is_min (min
) || !vrp_val_is_max (max
));
321 cmp
= compare_values (min
, max
);
322 gcc_assert (cmp
== 0 || cmp
== -1 || cmp
== -2);
324 if (needs_overflow_infinity (TREE_TYPE (min
)))
325 gcc_assert (!is_overflow_infinity (min
)
326 || !is_overflow_infinity (max
));
329 if (t
== VR_UNDEFINED
|| t
== VR_VARYING
)
330 gcc_assert (min
== NULL_TREE
&& max
== NULL_TREE
);
332 if (t
== VR_UNDEFINED
|| t
== VR_VARYING
)
333 gcc_assert (equiv
== NULL
|| bitmap_empty_p (equiv
));
340 /* Since updating the equivalence set involves deep copying the
341 bitmaps, only do it if absolutely necessary. */
342 if (vr
->equiv
== NULL
344 vr
->equiv
= BITMAP_ALLOC (NULL
);
346 if (equiv
!= vr
->equiv
)
348 if (equiv
&& !bitmap_empty_p (equiv
))
349 bitmap_copy (vr
->equiv
, equiv
);
351 bitmap_clear (vr
->equiv
);
356 /* Copy value range FROM into value range TO. */
359 copy_value_range (value_range_t
*to
, value_range_t
*from
)
361 set_value_range (to
, from
->type
, from
->min
, from
->max
, from
->equiv
);
365 /* Set value range VR to VR_VARYING. */
368 set_value_range_to_varying (value_range_t
*vr
)
370 vr
->type
= VR_VARYING
;
371 vr
->min
= vr
->max
= NULL_TREE
;
373 bitmap_clear (vr
->equiv
);
376 /* Set value range VR to a single value. This function is only called
377 with values we get from statements, and exists to clear the
378 TREE_OVERFLOW flag so that we don't think we have an overflow
379 infinity when we shouldn't. */
382 set_value_range_to_value (value_range_t
*vr
, tree val
, bitmap equiv
)
384 gcc_assert (is_gimple_min_invariant (val
));
385 val
= avoid_overflow_infinity (val
);
386 set_value_range (vr
, VR_RANGE
, val
, val
, equiv
);
389 /* Set value range VR to a non-negative range of type TYPE.
390 OVERFLOW_INFINITY indicates whether to use an overflow infinity
391 rather than TYPE_MAX_VALUE; this should be true if we determine
392 that the range is nonnegative based on the assumption that signed
393 overflow does not occur. */
396 set_value_range_to_nonnegative (value_range_t
*vr
, tree type
,
397 bool overflow_infinity
)
401 if (overflow_infinity
&& !supports_overflow_infinity (type
))
403 set_value_range_to_varying (vr
);
407 zero
= build_int_cst (type
, 0);
408 set_value_range (vr
, VR_RANGE
, zero
,
410 ? positive_overflow_infinity (type
)
411 : TYPE_MAX_VALUE (type
)),
415 /* Set value range VR to a non-NULL range of type TYPE. */
418 set_value_range_to_nonnull (value_range_t
*vr
, tree type
)
420 tree zero
= build_int_cst (type
, 0);
421 set_value_range (vr
, VR_ANTI_RANGE
, zero
, zero
, vr
->equiv
);
425 /* Set value range VR to a NULL range of type TYPE. */
428 set_value_range_to_null (value_range_t
*vr
, tree type
)
430 set_value_range_to_value (vr
, build_int_cst (type
, 0), vr
->equiv
);
434 /* Set value range VR to a range of a truthvalue of type TYPE. */
437 set_value_range_to_truthvalue (value_range_t
*vr
, tree type
)
439 if (TYPE_PRECISION (type
) == 1)
440 set_value_range_to_varying (vr
);
442 set_value_range (vr
, VR_RANGE
,
443 build_int_cst (type
, 0), build_int_cst (type
, 1),
448 /* Set value range VR to VR_UNDEFINED. */
451 set_value_range_to_undefined (value_range_t
*vr
)
453 vr
->type
= VR_UNDEFINED
;
454 vr
->min
= vr
->max
= NULL_TREE
;
456 bitmap_clear (vr
->equiv
);
460 /* Return value range information for VAR.
462 If we have no values ranges recorded (ie, VRP is not running), then
463 return NULL. Otherwise create an empty range if none existed for VAR. */
465 static value_range_t
*
466 get_value_range (tree var
)
470 unsigned ver
= SSA_NAME_VERSION (var
);
472 /* If we have no recorded ranges, then return NULL. */
480 /* Create a default value range. */
481 vr_value
[ver
] = vr
= XCNEW (value_range_t
);
483 /* Defer allocating the equivalence set. */
486 /* If VAR is a default definition, the variable can take any value
488 sym
= SSA_NAME_VAR (var
);
489 if (SSA_NAME_IS_DEFAULT_DEF (var
))
491 /* Try to use the "nonnull" attribute to create ~[0, 0]
492 anti-ranges for pointers. Note that this is only valid with
493 default definitions of PARM_DECLs. */
494 if (TREE_CODE (sym
) == PARM_DECL
495 && POINTER_TYPE_P (TREE_TYPE (sym
))
496 && nonnull_arg_p (sym
))
497 set_value_range_to_nonnull (vr
, TREE_TYPE (sym
));
499 set_value_range_to_varying (vr
);
505 /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */
508 vrp_operand_equal_p (tree val1
, tree val2
)
512 if (!val1
|| !val2
|| !operand_equal_p (val1
, val2
, 0))
514 if (is_overflow_infinity (val1
))
515 return is_overflow_infinity (val2
);
519 /* Return true, if the bitmaps B1 and B2 are equal. */
522 vrp_bitmap_equal_p (bitmap b1
, bitmap b2
)
526 && bitmap_equal_p (b1
, b2
)));
529 /* Update the value range and equivalence set for variable VAR to
530 NEW_VR. Return true if NEW_VR is different from VAR's previous
533 NOTE: This function assumes that NEW_VR is a temporary value range
534 object created for the sole purpose of updating VAR's range. The
535 storage used by the equivalence set from NEW_VR will be freed by
536 this function. Do not call update_value_range when NEW_VR
537 is the range object associated with another SSA name. */
540 update_value_range (tree var
, value_range_t
*new_vr
)
542 value_range_t
*old_vr
;
545 /* Update the value range, if necessary. */
546 old_vr
= get_value_range (var
);
547 is_new
= old_vr
->type
!= new_vr
->type
548 || !vrp_operand_equal_p (old_vr
->min
, new_vr
->min
)
549 || !vrp_operand_equal_p (old_vr
->max
, new_vr
->max
)
550 || !vrp_bitmap_equal_p (old_vr
->equiv
, new_vr
->equiv
);
553 set_value_range (old_vr
, new_vr
->type
, new_vr
->min
, new_vr
->max
,
556 BITMAP_FREE (new_vr
->equiv
);
562 /* Add VAR and VAR's equivalence set to EQUIV. This is the central
563 point where equivalence processing can be turned on/off. */
566 add_equivalence (bitmap
*equiv
, tree var
)
568 unsigned ver
= SSA_NAME_VERSION (var
);
569 value_range_t
*vr
= vr_value
[ver
];
572 *equiv
= BITMAP_ALLOC (NULL
);
573 bitmap_set_bit (*equiv
, ver
);
575 bitmap_ior_into (*equiv
, vr
->equiv
);
579 /* Return true if VR is ~[0, 0]. */
582 range_is_nonnull (value_range_t
*vr
)
584 return vr
->type
== VR_ANTI_RANGE
585 && integer_zerop (vr
->min
)
586 && integer_zerop (vr
->max
);
590 /* Return true if VR is [0, 0]. */
593 range_is_null (value_range_t
*vr
)
595 return vr
->type
== VR_RANGE
596 && integer_zerop (vr
->min
)
597 && integer_zerop (vr
->max
);
601 /* Return true if value range VR involves at least one symbol. */
604 symbolic_range_p (value_range_t
*vr
)
606 return (!is_gimple_min_invariant (vr
->min
)
607 || !is_gimple_min_invariant (vr
->max
));
610 /* Return true if value range VR uses an overflow infinity. */
613 overflow_infinity_range_p (value_range_t
*vr
)
615 return (vr
->type
== VR_RANGE
616 && (is_overflow_infinity (vr
->min
)
617 || is_overflow_infinity (vr
->max
)));
620 /* Return false if we can not make a valid comparison based on VR;
621 this will be the case if it uses an overflow infinity and overflow
622 is not undefined (i.e., -fno-strict-overflow is in effect).
623 Otherwise return true, and set *STRICT_OVERFLOW_P to true if VR
624 uses an overflow infinity. */
627 usable_range_p (value_range_t
*vr
, bool *strict_overflow_p
)
629 gcc_assert (vr
->type
== VR_RANGE
);
630 if (is_overflow_infinity (vr
->min
))
632 *strict_overflow_p
= true;
633 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr
->min
)))
636 if (is_overflow_infinity (vr
->max
))
638 *strict_overflow_p
= true;
639 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr
->max
)))
646 /* Like tree_expr_nonnegative_warnv_p, but this function uses value
647 ranges obtained so far. */
650 vrp_expr_computes_nonnegative (tree expr
, bool *strict_overflow_p
)
652 return tree_expr_nonnegative_warnv_p (expr
, strict_overflow_p
);
655 /* Like tree_expr_nonzero_warnv_p, but this function uses value ranges
659 vrp_expr_computes_nonzero (tree expr
, bool *strict_overflow_p
)
661 if (tree_expr_nonzero_warnv_p (expr
, strict_overflow_p
))
664 /* If we have an expression of the form &X->a, then the expression
665 is nonnull if X is nonnull. */
666 if (TREE_CODE (expr
) == ADDR_EXPR
)
668 tree base
= get_base_address (TREE_OPERAND (expr
, 0));
670 if (base
!= NULL_TREE
671 && TREE_CODE (base
) == INDIRECT_REF
672 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
674 value_range_t
*vr
= get_value_range (TREE_OPERAND (base
, 0));
675 if (range_is_nonnull (vr
))
683 /* Returns true if EXPR is a valid value (as expected by compare_values) --
684 a gimple invariant, or SSA_NAME +- CST. */
687 valid_value_p (tree expr
)
689 if (TREE_CODE (expr
) == SSA_NAME
)
692 if (TREE_CODE (expr
) == PLUS_EXPR
693 || TREE_CODE (expr
) == MINUS_EXPR
)
694 return (TREE_CODE (TREE_OPERAND (expr
, 0)) == SSA_NAME
695 && TREE_CODE (TREE_OPERAND (expr
, 1)) == INTEGER_CST
);
697 return is_gimple_min_invariant (expr
);
703 -2 if those are incomparable. */
705 operand_less_p (tree val
, tree val2
)
707 /* LT is folded faster than GE and others. Inline the common case. */
708 if (TREE_CODE (val
) == INTEGER_CST
&& TREE_CODE (val2
) == INTEGER_CST
)
710 if (TYPE_UNSIGNED (TREE_TYPE (val
)))
711 return INT_CST_LT_UNSIGNED (val
, val2
);
714 if (INT_CST_LT (val
, val2
))
722 fold_defer_overflow_warnings ();
724 tcmp
= fold_binary_to_constant (LT_EXPR
, boolean_type_node
, val
, val2
);
726 fold_undefer_and_ignore_overflow_warnings ();
731 if (!integer_zerop (tcmp
))
735 /* val >= val2, not considering overflow infinity. */
736 if (is_negative_overflow_infinity (val
))
737 return is_negative_overflow_infinity (val2
) ? 0 : 1;
738 else if (is_positive_overflow_infinity (val2
))
739 return is_positive_overflow_infinity (val
) ? 0 : 1;
744 /* Compare two values VAL1 and VAL2. Return
746 -2 if VAL1 and VAL2 cannot be compared at compile-time,
749 +1 if VAL1 > VAL2, and
752 This is similar to tree_int_cst_compare but supports pointer values
753 and values that cannot be compared at compile time.
755 If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to
756 true if the return value is only valid if we assume that signed
757 overflow is undefined. */
760 compare_values_warnv (tree val1
, tree val2
, bool *strict_overflow_p
)
765 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
767 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1
))
768 == POINTER_TYPE_P (TREE_TYPE (val2
)));
769 /* Convert the two values into the same type. This is needed because
770 sizetype causes sign extension even for unsigned types. */
771 val2
= fold_convert (TREE_TYPE (val1
), val2
);
772 STRIP_USELESS_TYPE_CONVERSION (val2
);
774 if ((TREE_CODE (val1
) == SSA_NAME
775 || TREE_CODE (val1
) == PLUS_EXPR
776 || TREE_CODE (val1
) == MINUS_EXPR
)
777 && (TREE_CODE (val2
) == SSA_NAME
778 || TREE_CODE (val2
) == PLUS_EXPR
779 || TREE_CODE (val2
) == MINUS_EXPR
))
782 enum tree_code code1
, code2
;
784 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
785 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
786 same name, return -2. */
787 if (TREE_CODE (val1
) == SSA_NAME
)
795 code1
= TREE_CODE (val1
);
796 n1
= TREE_OPERAND (val1
, 0);
797 c1
= TREE_OPERAND (val1
, 1);
798 if (tree_int_cst_sgn (c1
) == -1)
800 if (is_negative_overflow_infinity (c1
))
802 c1
= fold_unary_to_constant (NEGATE_EXPR
, TREE_TYPE (c1
), c1
);
805 code1
= code1
== MINUS_EXPR
? PLUS_EXPR
: MINUS_EXPR
;
809 if (TREE_CODE (val2
) == SSA_NAME
)
817 code2
= TREE_CODE (val2
);
818 n2
= TREE_OPERAND (val2
, 0);
819 c2
= TREE_OPERAND (val2
, 1);
820 if (tree_int_cst_sgn (c2
) == -1)
822 if (is_negative_overflow_infinity (c2
))
824 c2
= fold_unary_to_constant (NEGATE_EXPR
, TREE_TYPE (c2
), c2
);
827 code2
= code2
== MINUS_EXPR
? PLUS_EXPR
: MINUS_EXPR
;
831 /* Both values must use the same name. */
835 if (code1
== SSA_NAME
836 && code2
== SSA_NAME
)
840 /* If overflow is defined we cannot simplify more. */
841 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1
)))
844 if (strict_overflow_p
!= NULL
845 && (code1
== SSA_NAME
|| !TREE_NO_WARNING (val1
))
846 && (code2
== SSA_NAME
|| !TREE_NO_WARNING (val2
)))
847 *strict_overflow_p
= true;
849 if (code1
== SSA_NAME
)
851 if (code2
== PLUS_EXPR
)
852 /* NAME < NAME + CST */
854 else if (code2
== MINUS_EXPR
)
855 /* NAME > NAME - CST */
858 else if (code1
== PLUS_EXPR
)
860 if (code2
== SSA_NAME
)
861 /* NAME + CST > NAME */
863 else if (code2
== PLUS_EXPR
)
864 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
865 return compare_values_warnv (c1
, c2
, strict_overflow_p
);
866 else if (code2
== MINUS_EXPR
)
867 /* NAME + CST1 > NAME - CST2 */
870 else if (code1
== MINUS_EXPR
)
872 if (code2
== SSA_NAME
)
873 /* NAME - CST < NAME */
875 else if (code2
== PLUS_EXPR
)
876 /* NAME - CST1 < NAME + CST2 */
878 else if (code2
== MINUS_EXPR
)
879 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
880 C1 and C2 are swapped in the call to compare_values. */
881 return compare_values_warnv (c2
, c1
, strict_overflow_p
);
887 /* We cannot compare non-constants. */
888 if (!is_gimple_min_invariant (val1
) || !is_gimple_min_invariant (val2
))
891 if (!POINTER_TYPE_P (TREE_TYPE (val1
)))
893 /* We cannot compare overflowed values, except for overflow
895 if (TREE_OVERFLOW (val1
) || TREE_OVERFLOW (val2
))
897 if (strict_overflow_p
!= NULL
)
898 *strict_overflow_p
= true;
899 if (is_negative_overflow_infinity (val1
))
900 return is_negative_overflow_infinity (val2
) ? 0 : -1;
901 else if (is_negative_overflow_infinity (val2
))
903 else if (is_positive_overflow_infinity (val1
))
904 return is_positive_overflow_infinity (val2
) ? 0 : 1;
905 else if (is_positive_overflow_infinity (val2
))
910 return tree_int_cst_compare (val1
, val2
);
916 /* First see if VAL1 and VAL2 are not the same. */
917 if (val1
== val2
|| operand_equal_p (val1
, val2
, 0))
920 /* If VAL1 is a lower address than VAL2, return -1. */
921 if (operand_less_p (val1
, val2
) == 1)
924 /* If VAL1 is a higher address than VAL2, return +1. */
925 if (operand_less_p (val2
, val1
) == 1)
928 /* If VAL1 is different than VAL2, return +2.
929 For integer constants we either have already returned -1 or 1
930 or they are equivalent. We still might succeed in proving
931 something about non-trivial operands. */
932 if (TREE_CODE (val1
) != INTEGER_CST
933 || TREE_CODE (val2
) != INTEGER_CST
)
935 t
= fold_binary_to_constant (NE_EXPR
, boolean_type_node
, val1
, val2
);
936 if (t
&& tree_expr_nonzero_p (t
))
944 /* Compare values like compare_values_warnv, but treat comparisons of
945 nonconstants which rely on undefined overflow as incomparable. */
948 compare_values (tree val1
, tree val2
)
954 ret
= compare_values_warnv (val1
, val2
, &sop
);
956 && (!is_gimple_min_invariant (val1
) || !is_gimple_min_invariant (val2
)))
962 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
963 0 if VAL is not inside VR,
964 -2 if we cannot tell either way.
966 FIXME, the current semantics of this functions are a bit quirky
967 when taken in the context of VRP. In here we do not care
968 about VR's type. If VR is the anti-range ~[3, 5] the call
969 value_inside_range (4, VR) will return 1.
971 This is counter-intuitive in a strict sense, but the callers
972 currently expect this. They are calling the function
973 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
974 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
977 This also applies to value_ranges_intersect_p and
978 range_includes_zero_p. The semantics of VR_RANGE and
979 VR_ANTI_RANGE should be encoded here, but that also means
980 adapting the users of these functions to the new semantics.
982 Benchmark compile/20001226-1.c compilation time after changing this
986 value_inside_range (tree val
, value_range_t
* vr
)
990 cmp1
= operand_less_p (val
, vr
->min
);
996 cmp2
= operand_less_p (vr
->max
, val
);
1004 /* Return true if value ranges VR0 and VR1 have a non-empty
1007 Benchmark compile/20001226-1.c compilation time after changing this
1012 value_ranges_intersect_p (value_range_t
*vr0
, value_range_t
*vr1
)
1014 /* The value ranges do not intersect if the maximum of the first range is
1015 less than the minimum of the second range or vice versa.
1016 When those relations are unknown, we can't do any better. */
1017 if (operand_less_p (vr0
->max
, vr1
->min
) != 0)
1019 if (operand_less_p (vr1
->max
, vr0
->min
) != 0)
1025 /* Return true if VR includes the value zero, false otherwise. FIXME,
1026 currently this will return false for an anti-range like ~[-4, 3].
1027 This will be wrong when the semantics of value_inside_range are
1028 modified (currently the users of this function expect these
1032 range_includes_zero_p (value_range_t
*vr
)
1036 gcc_assert (vr
->type
!= VR_UNDEFINED
1037 && vr
->type
!= VR_VARYING
1038 && !symbolic_range_p (vr
));
1040 zero
= build_int_cst (TREE_TYPE (vr
->min
), 0);
1041 return (value_inside_range (zero
, vr
) == 1);
1044 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
1045 false otherwise or if no value range information is available. */
1048 ssa_name_nonnegative_p (tree t
)
1050 value_range_t
*vr
= get_value_range (t
);
1055 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
1056 which would return a useful value should be encoded as a VR_RANGE. */
1057 if (vr
->type
== VR_RANGE
)
1059 int result
= compare_values (vr
->min
, integer_zero_node
);
1061 return (result
== 0 || result
== 1);
1066 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
1067 false otherwise or if no value range information is available. */
1070 ssa_name_nonzero_p (tree t
)
1072 value_range_t
*vr
= get_value_range (t
);
1077 /* A VR_RANGE which does not include zero is a nonzero value. */
1078 if (vr
->type
== VR_RANGE
&& !symbolic_range_p (vr
))
1079 return ! range_includes_zero_p (vr
);
1081 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
1082 if (vr
->type
== VR_ANTI_RANGE
&& !symbolic_range_p (vr
))
1083 return range_includes_zero_p (vr
);
1089 /* Extract value range information from an ASSERT_EXPR EXPR and store
1093 extract_range_from_assert (value_range_t
*vr_p
, tree expr
)
1095 tree var
, cond
, limit
, min
, max
, type
;
1096 value_range_t
*var_vr
, *limit_vr
;
1097 enum tree_code cond_code
;
1099 var
= ASSERT_EXPR_VAR (expr
);
1100 cond
= ASSERT_EXPR_COND (expr
);
1102 gcc_assert (COMPARISON_CLASS_P (cond
));
1104 /* Find VAR in the ASSERT_EXPR conditional. */
1105 if (var
== TREE_OPERAND (cond
, 0))
1107 /* If the predicate is of the form VAR COMP LIMIT, then we just
1108 take LIMIT from the RHS and use the same comparison code. */
1109 limit
= TREE_OPERAND (cond
, 1);
1110 cond_code
= TREE_CODE (cond
);
1114 /* If the predicate is of the form LIMIT COMP VAR, then we need
1115 to flip around the comparison code to create the proper range
1117 limit
= TREE_OPERAND (cond
, 0);
1118 cond_code
= swap_tree_comparison (TREE_CODE (cond
));
1121 limit
= avoid_overflow_infinity (limit
);
1123 type
= TREE_TYPE (limit
);
1124 gcc_assert (limit
!= var
);
1126 /* For pointer arithmetic, we only keep track of pointer equality
1128 if (POINTER_TYPE_P (type
) && cond_code
!= NE_EXPR
&& cond_code
!= EQ_EXPR
)
1130 set_value_range_to_varying (vr_p
);
1134 /* If LIMIT is another SSA name and LIMIT has a range of its own,
1135 try to use LIMIT's range to avoid creating symbolic ranges
1137 limit_vr
= (TREE_CODE (limit
) == SSA_NAME
) ? get_value_range (limit
) : NULL
;
1139 /* LIMIT's range is only interesting if it has any useful information. */
1141 && (limit_vr
->type
== VR_UNDEFINED
1142 || limit_vr
->type
== VR_VARYING
1143 || symbolic_range_p (limit_vr
)))
1146 /* Initially, the new range has the same set of equivalences of
1147 VAR's range. This will be revised before returning the final
1148 value. Since assertions may be chained via mutually exclusive
1149 predicates, we will need to trim the set of equivalences before
1151 gcc_assert (vr_p
->equiv
== NULL
);
1152 add_equivalence (&vr_p
->equiv
, var
);
1154 /* Extract a new range based on the asserted comparison for VAR and
1155 LIMIT's value range. Notice that if LIMIT has an anti-range, we
1156 will only use it for equality comparisons (EQ_EXPR). For any
1157 other kind of assertion, we cannot derive a range from LIMIT's
1158 anti-range that can be used to describe the new range. For
1159 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
1160 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
1161 no single range for x_2 that could describe LE_EXPR, so we might
1162 as well build the range [b_4, +INF] for it. */
1163 if (cond_code
== EQ_EXPR
)
1165 enum value_range_type range_type
;
1169 range_type
= limit_vr
->type
;
1170 min
= limit_vr
->min
;
1171 max
= limit_vr
->max
;
1175 range_type
= VR_RANGE
;
1180 set_value_range (vr_p
, range_type
, min
, max
, vr_p
->equiv
);
1182 /* When asserting the equality VAR == LIMIT and LIMIT is another
1183 SSA name, the new range will also inherit the equivalence set
1185 if (TREE_CODE (limit
) == SSA_NAME
)
1186 add_equivalence (&vr_p
->equiv
, limit
);
1188 else if (cond_code
== NE_EXPR
)
1190 /* As described above, when LIMIT's range is an anti-range and
1191 this assertion is an inequality (NE_EXPR), then we cannot
1192 derive anything from the anti-range. For instance, if
1193 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
1194 not imply that VAR's range is [0, 0]. So, in the case of
1195 anti-ranges, we just assert the inequality using LIMIT and
1198 If LIMIT_VR is a range, we can only use it to build a new
1199 anti-range if LIMIT_VR is a single-valued range. For
1200 instance, if LIMIT_VR is [0, 1], the predicate
1201 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
1202 Rather, it means that for value 0 VAR should be ~[0, 0]
1203 and for value 1, VAR should be ~[1, 1]. We cannot
1204 represent these ranges.
1206 The only situation in which we can build a valid
1207 anti-range is when LIMIT_VR is a single-valued range
1208 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
1209 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
1211 && limit_vr
->type
== VR_RANGE
1212 && compare_values (limit_vr
->min
, limit_vr
->max
) == 0)
1214 min
= limit_vr
->min
;
1215 max
= limit_vr
->max
;
1219 /* In any other case, we cannot use LIMIT's range to build a
1220 valid anti-range. */
1224 /* If MIN and MAX cover the whole range for their type, then
1225 just use the original LIMIT. */
1226 if (INTEGRAL_TYPE_P (type
)
1227 && vrp_val_is_min (min
)
1228 && vrp_val_is_max (max
))
1231 set_value_range (vr_p
, VR_ANTI_RANGE
, min
, max
, vr_p
->equiv
);
1233 else if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
1235 min
= TYPE_MIN_VALUE (type
);
1237 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
1241 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1242 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
1244 max
= limit_vr
->max
;
1247 /* If the maximum value forces us to be out of bounds, simply punt.
1248 It would be pointless to try and do anything more since this
1249 all should be optimized away above us. */
1250 if ((cond_code
== LT_EXPR
1251 && compare_values (max
, min
) == 0)
1252 || is_overflow_infinity (max
))
1253 set_value_range_to_varying (vr_p
);
1256 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
1257 if (cond_code
== LT_EXPR
)
1259 tree one
= build_int_cst (type
, 1);
1260 max
= fold_build2 (MINUS_EXPR
, type
, max
, one
);
1262 TREE_NO_WARNING (max
) = 1;
1265 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1268 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
1270 max
= TYPE_MAX_VALUE (type
);
1272 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
1276 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1277 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
1279 min
= limit_vr
->min
;
1282 /* If the minimum value forces us to be out of bounds, simply punt.
1283 It would be pointless to try and do anything more since this
1284 all should be optimized away above us. */
1285 if ((cond_code
== GT_EXPR
1286 && compare_values (min
, max
) == 0)
1287 || is_overflow_infinity (min
))
1288 set_value_range_to_varying (vr_p
);
1291 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
1292 if (cond_code
== GT_EXPR
)
1294 tree one
= build_int_cst (type
, 1);
1295 min
= fold_build2 (PLUS_EXPR
, type
, min
, one
);
1297 TREE_NO_WARNING (min
) = 1;
1300 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1306 /* If VAR already had a known range, it may happen that the new
1307 range we have computed and VAR's range are not compatible. For
1311 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
1313 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
1315 While the above comes from a faulty program, it will cause an ICE
1316 later because p_8 and p_6 will have incompatible ranges and at
1317 the same time will be considered equivalent. A similar situation
1321 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
1323 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
1325 Again i_6 and i_7 will have incompatible ranges. It would be
1326 pointless to try and do anything with i_7's range because
1327 anything dominated by 'if (i_5 < 5)' will be optimized away.
1328 Note, due to the wa in which simulation proceeds, the statement
1329 i_7 = ASSERT_EXPR <...> we would never be visited because the
1330 conditional 'if (i_5 < 5)' always evaluates to false. However,
1331 this extra check does not hurt and may protect against future
1332 changes to VRP that may get into a situation similar to the
1333 NULL pointer dereference example.
1335 Note that these compatibility tests are only needed when dealing
1336 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1337 are both anti-ranges, they will always be compatible, because two
1338 anti-ranges will always have a non-empty intersection. */
1340 var_vr
= get_value_range (var
);
1342 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1343 ranges or anti-ranges. */
1344 if (vr_p
->type
== VR_VARYING
1345 || vr_p
->type
== VR_UNDEFINED
1346 || var_vr
->type
== VR_VARYING
1347 || var_vr
->type
== VR_UNDEFINED
1348 || symbolic_range_p (vr_p
)
1349 || symbolic_range_p (var_vr
))
1352 if (var_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_RANGE
)
1354 /* If the two ranges have a non-empty intersection, we can
1355 refine the resulting range. Since the assert expression
1356 creates an equivalency and at the same time it asserts a
1357 predicate, we can take the intersection of the two ranges to
1358 get better precision. */
1359 if (value_ranges_intersect_p (var_vr
, vr_p
))
1361 /* Use the larger of the two minimums. */
1362 if (compare_values (vr_p
->min
, var_vr
->min
) == -1)
1367 /* Use the smaller of the two maximums. */
1368 if (compare_values (vr_p
->max
, var_vr
->max
) == 1)
1373 set_value_range (vr_p
, vr_p
->type
, min
, max
, vr_p
->equiv
);
1377 /* The two ranges do not intersect, set the new range to
1378 VARYING, because we will not be able to do anything
1379 meaningful with it. */
1380 set_value_range_to_varying (vr_p
);
1383 else if ((var_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_ANTI_RANGE
)
1384 || (var_vr
->type
== VR_ANTI_RANGE
&& vr_p
->type
== VR_RANGE
))
1386 /* A range and an anti-range will cancel each other only if
1387 their ends are the same. For instance, in the example above,
1388 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1389 so VR_P should be set to VR_VARYING. */
1390 if (compare_values (var_vr
->min
, vr_p
->min
) == 0
1391 && compare_values (var_vr
->max
, vr_p
->max
) == 0)
1392 set_value_range_to_varying (vr_p
);
1395 tree min
, max
, anti_min
, anti_max
, real_min
, real_max
;
1398 /* We want to compute the logical AND of the two ranges;
1399 there are three cases to consider.
1402 1. The VR_ANTI_RANGE range is completely within the
1403 VR_RANGE and the endpoints of the ranges are
1404 different. In that case the resulting range
1405 should be whichever range is more precise.
1406 Typically that will be the VR_RANGE.
1408 2. The VR_ANTI_RANGE is completely disjoint from
1409 the VR_RANGE. In this case the resulting range
1410 should be the VR_RANGE.
1412 3. There is some overlap between the VR_ANTI_RANGE
1415 3a. If the high limit of the VR_ANTI_RANGE resides
1416 within the VR_RANGE, then the result is a new
1417 VR_RANGE starting at the high limit of the
1418 the VR_ANTI_RANGE + 1 and extending to the
1419 high limit of the original VR_RANGE.
1421 3b. If the low limit of the VR_ANTI_RANGE resides
1422 within the VR_RANGE, then the result is a new
1423 VR_RANGE starting at the low limit of the original
1424 VR_RANGE and extending to the low limit of the
1425 VR_ANTI_RANGE - 1. */
1426 if (vr_p
->type
== VR_ANTI_RANGE
)
1428 anti_min
= vr_p
->min
;
1429 anti_max
= vr_p
->max
;
1430 real_min
= var_vr
->min
;
1431 real_max
= var_vr
->max
;
1435 anti_min
= var_vr
->min
;
1436 anti_max
= var_vr
->max
;
1437 real_min
= vr_p
->min
;
1438 real_max
= vr_p
->max
;
1442 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1443 not including any endpoints. */
1444 if (compare_values (anti_max
, real_max
) == -1
1445 && compare_values (anti_min
, real_min
) == 1)
1447 set_value_range (vr_p
, VR_RANGE
, real_min
,
1448 real_max
, vr_p
->equiv
);
1450 /* Case 2, VR_ANTI_RANGE completely disjoint from
1452 else if (compare_values (anti_min
, real_max
) == 1
1453 || compare_values (anti_max
, real_min
) == -1)
1455 set_value_range (vr_p
, VR_RANGE
, real_min
,
1456 real_max
, vr_p
->equiv
);
1458 /* Case 3a, the anti-range extends into the low
1459 part of the real range. Thus creating a new
1460 low for the real range. */
1461 else if (((cmp
= compare_values (anti_max
, real_min
)) == 1
1463 && compare_values (anti_max
, real_max
) == -1)
1465 gcc_assert (!is_positive_overflow_infinity (anti_max
));
1466 if (needs_overflow_infinity (TREE_TYPE (anti_max
))
1467 && vrp_val_is_max (anti_max
))
1469 if (!supports_overflow_infinity (TREE_TYPE (var_vr
->min
)))
1471 set_value_range_to_varying (vr_p
);
1474 min
= positive_overflow_infinity (TREE_TYPE (var_vr
->min
));
1476 else if (!POINTER_TYPE_P (TREE_TYPE (var_vr
->min
)))
1477 min
= fold_build2 (PLUS_EXPR
, TREE_TYPE (var_vr
->min
),
1479 build_int_cst (TREE_TYPE (var_vr
->min
), 1));
1481 min
= fold_build2 (POINTER_PLUS_EXPR
, TREE_TYPE (var_vr
->min
),
1482 anti_max
, size_int (1));
1484 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1486 /* Case 3b, the anti-range extends into the high
1487 part of the real range. Thus creating a new
1488 higher for the real range. */
1489 else if (compare_values (anti_min
, real_min
) == 1
1490 && ((cmp
= compare_values (anti_min
, real_max
)) == -1
1493 gcc_assert (!is_negative_overflow_infinity (anti_min
));
1494 if (needs_overflow_infinity (TREE_TYPE (anti_min
))
1495 && vrp_val_is_min (anti_min
))
1497 if (!supports_overflow_infinity (TREE_TYPE (var_vr
->min
)))
1499 set_value_range_to_varying (vr_p
);
1502 max
= negative_overflow_infinity (TREE_TYPE (var_vr
->min
));
1504 else if (!POINTER_TYPE_P (TREE_TYPE (var_vr
->min
)))
1505 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (var_vr
->min
),
1507 build_int_cst (TREE_TYPE (var_vr
->min
), 1));
1509 max
= fold_build2 (POINTER_PLUS_EXPR
, TREE_TYPE (var_vr
->min
),
1513 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1520 /* Extract range information from SSA name VAR and store it in VR. If
1521 VAR has an interesting range, use it. Otherwise, create the
1522 range [VAR, VAR] and return it. This is useful in situations where
1523 we may have conditionals testing values of VARYING names. For
1530 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1534 extract_range_from_ssa_name (value_range_t
*vr
, tree var
)
1536 value_range_t
*var_vr
= get_value_range (var
);
1538 if (var_vr
->type
!= VR_UNDEFINED
&& var_vr
->type
!= VR_VARYING
)
1539 copy_value_range (vr
, var_vr
);
1541 set_value_range (vr
, VR_RANGE
, var
, var
, NULL
);
1543 add_equivalence (&vr
->equiv
, var
);
1547 /* Wrapper around int_const_binop. If the operation overflows and we
1548 are not using wrapping arithmetic, then adjust the result to be
1549 -INF or +INF depending on CODE, VAL1 and VAL2. This can return
1550 NULL_TREE if we need to use an overflow infinity representation but
1551 the type does not support it. */
1554 vrp_int_const_binop (enum tree_code code
, tree val1
, tree val2
)
1558 res
= int_const_binop (code
, val1
, val2
, 0);
1560 /* If we are not using wrapping arithmetic, operate symbolically
1561 on -INF and +INF. */
1562 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1
)))
1564 int checkz
= compare_values (res
, val1
);
1565 bool overflow
= false;
1567 /* Ensure that res = val1 [+*] val2 >= val1
1568 or that res = val1 - val2 <= val1. */
1569 if ((code
== PLUS_EXPR
1570 && !(checkz
== 1 || checkz
== 0))
1571 || (code
== MINUS_EXPR
1572 && !(checkz
== 0 || checkz
== -1)))
1576 /* Checking for multiplication overflow is done by dividing the
1577 output of the multiplication by the first input of the
1578 multiplication. If the result of that division operation is
1579 not equal to the second input of the multiplication, then the
1580 multiplication overflowed. */
1581 else if (code
== MULT_EXPR
&& !integer_zerop (val1
))
1583 tree tmp
= int_const_binop (TRUNC_DIV_EXPR
,
1586 int check
= compare_values (tmp
, val2
);
1594 res
= copy_node (res
);
1595 TREE_OVERFLOW (res
) = 1;
1599 else if ((TREE_OVERFLOW (res
)
1600 && !TREE_OVERFLOW (val1
)
1601 && !TREE_OVERFLOW (val2
))
1602 || is_overflow_infinity (val1
)
1603 || is_overflow_infinity (val2
))
1605 /* If the operation overflowed but neither VAL1 nor VAL2 are
1606 overflown, return -INF or +INF depending on the operation
1607 and the combination of signs of the operands. */
1608 int sgn1
= tree_int_cst_sgn (val1
);
1609 int sgn2
= tree_int_cst_sgn (val2
);
1611 if (needs_overflow_infinity (TREE_TYPE (res
))
1612 && !supports_overflow_infinity (TREE_TYPE (res
)))
1615 /* We have to punt on adding infinities of different signs,
1616 since we can't tell what the sign of the result should be.
1617 Likewise for subtracting infinities of the same sign. */
1618 if (((code
== PLUS_EXPR
&& sgn1
!= sgn2
)
1619 || (code
== MINUS_EXPR
&& sgn1
== sgn2
))
1620 && is_overflow_infinity (val1
)
1621 && is_overflow_infinity (val2
))
1624 /* Don't try to handle division or shifting of infinities. */
1625 if ((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
)
1631 && (is_overflow_infinity (val1
)
1632 || is_overflow_infinity (val2
)))
1635 /* Notice that we only need to handle the restricted set of
1636 operations handled by extract_range_from_binary_expr.
1637 Among them, only multiplication, addition and subtraction
1638 can yield overflow without overflown operands because we
1639 are working with integral types only... except in the
1640 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1641 for division too. */
1643 /* For multiplication, the sign of the overflow is given
1644 by the comparison of the signs of the operands. */
1645 if ((code
== MULT_EXPR
&& sgn1
== sgn2
)
1646 /* For addition, the operands must be of the same sign
1647 to yield an overflow. Its sign is therefore that
1648 of one of the operands, for example the first. For
1649 infinite operands X + -INF is negative, not positive. */
1650 || (code
== PLUS_EXPR
1652 ? !is_negative_overflow_infinity (val2
)
1653 : is_positive_overflow_infinity (val2
)))
1654 /* For subtraction, non-infinite operands must be of
1655 different signs to yield an overflow. Its sign is
1656 therefore that of the first operand or the opposite of
1657 that of the second operand. A first operand of 0 counts
1658 as positive here, for the corner case 0 - (-INF), which
1659 overflows, but must yield +INF. For infinite operands 0
1660 - INF is negative, not positive. */
1661 || (code
== MINUS_EXPR
1663 ? !is_positive_overflow_infinity (val2
)
1664 : is_negative_overflow_infinity (val2
)))
1665 /* We only get in here with positive shift count, so the
1666 overflow direction is the same as the sign of val1.
1667 Actually rshift does not overflow at all, but we only
1668 handle the case of shifting overflowed -INF and +INF. */
1669 || (code
== RSHIFT_EXPR
1671 /* For division, the only case is -INF / -1 = +INF. */
1672 || code
== TRUNC_DIV_EXPR
1673 || code
== FLOOR_DIV_EXPR
1674 || code
== CEIL_DIV_EXPR
1675 || code
== EXACT_DIV_EXPR
1676 || code
== ROUND_DIV_EXPR
)
1677 return (needs_overflow_infinity (TREE_TYPE (res
))
1678 ? positive_overflow_infinity (TREE_TYPE (res
))
1679 : TYPE_MAX_VALUE (TREE_TYPE (res
)));
1681 return (needs_overflow_infinity (TREE_TYPE (res
))
1682 ? negative_overflow_infinity (TREE_TYPE (res
))
1683 : TYPE_MIN_VALUE (TREE_TYPE (res
)));
1690 /* Extract range information from a binary expression EXPR based on
1691 the ranges of each of its operands and the expression code. */
1694 extract_range_from_binary_expr (value_range_t
*vr
, tree expr
)
1696 enum tree_code code
= TREE_CODE (expr
);
1697 enum value_range_type type
;
1698 tree op0
, op1
, min
, max
;
1700 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1701 value_range_t vr1
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1703 /* Not all binary expressions can be applied to ranges in a
1704 meaningful way. Handle only arithmetic operations. */
1705 if (code
!= PLUS_EXPR
1706 && code
!= MINUS_EXPR
1707 && code
!= POINTER_PLUS_EXPR
1708 && code
!= MULT_EXPR
1709 && code
!= TRUNC_DIV_EXPR
1710 && code
!= FLOOR_DIV_EXPR
1711 && code
!= CEIL_DIV_EXPR
1712 && code
!= EXACT_DIV_EXPR
1713 && code
!= ROUND_DIV_EXPR
1714 && code
!= RSHIFT_EXPR
1717 && code
!= BIT_AND_EXPR
1718 && code
!= TRUTH_ANDIF_EXPR
1719 && code
!= TRUTH_ORIF_EXPR
1720 && code
!= TRUTH_AND_EXPR
1721 && code
!= TRUTH_OR_EXPR
)
1723 set_value_range_to_varying (vr
);
1727 /* Get value ranges for each operand. For constant operands, create
1728 a new value range with the operand to simplify processing. */
1729 op0
= TREE_OPERAND (expr
, 0);
1730 if (TREE_CODE (op0
) == SSA_NAME
)
1731 vr0
= *(get_value_range (op0
));
1732 else if (is_gimple_min_invariant (op0
))
1733 set_value_range_to_value (&vr0
, op0
, NULL
);
1735 set_value_range_to_varying (&vr0
);
1737 op1
= TREE_OPERAND (expr
, 1);
1738 if (TREE_CODE (op1
) == SSA_NAME
)
1739 vr1
= *(get_value_range (op1
));
1740 else if (is_gimple_min_invariant (op1
))
1741 set_value_range_to_value (&vr1
, op1
, NULL
);
1743 set_value_range_to_varying (&vr1
);
1745 /* If either range is UNDEFINED, so is the result. */
1746 if (vr0
.type
== VR_UNDEFINED
|| vr1
.type
== VR_UNDEFINED
)
1748 set_value_range_to_undefined (vr
);
1752 /* The type of the resulting value range defaults to VR0.TYPE. */
1755 /* Refuse to operate on VARYING ranges, ranges of different kinds
1756 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1757 because we may be able to derive a useful range even if one of
1758 the operands is VR_VARYING or symbolic range. TODO, we may be
1759 able to derive anti-ranges in some cases. */
1760 if (code
!= BIT_AND_EXPR
1761 && code
!= TRUTH_AND_EXPR
1762 && code
!= TRUTH_OR_EXPR
1763 && (vr0
.type
== VR_VARYING
1764 || vr1
.type
== VR_VARYING
1765 || vr0
.type
!= vr1
.type
1766 || symbolic_range_p (&vr0
)
1767 || symbolic_range_p (&vr1
)))
1769 set_value_range_to_varying (vr
);
1773 /* Now evaluate the expression to determine the new range. */
1774 if (POINTER_TYPE_P (TREE_TYPE (expr
))
1775 || POINTER_TYPE_P (TREE_TYPE (op0
))
1776 || POINTER_TYPE_P (TREE_TYPE (op1
)))
1778 if (code
== MIN_EXPR
|| code
== MAX_EXPR
)
1780 /* For MIN/MAX expressions with pointers, we only care about
1781 nullness, if both are non null, then the result is nonnull.
1782 If both are null, then the result is null. Otherwise they
1784 if (range_is_nonnull (&vr0
) && range_is_nonnull (&vr1
))
1785 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1786 else if (range_is_null (&vr0
) && range_is_null (&vr1
))
1787 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1789 set_value_range_to_varying (vr
);
1793 gcc_assert (code
== POINTER_PLUS_EXPR
);
1794 /* For pointer types, we are really only interested in asserting
1795 whether the expression evaluates to non-NULL. */
1796 if (range_is_nonnull (&vr0
) || range_is_nonnull (&vr1
))
1797 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1798 else if (range_is_null (&vr0
) && range_is_null (&vr1
))
1799 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1801 set_value_range_to_varying (vr
);
1806 /* For integer ranges, apply the operation to each end of the
1807 range and see what we end up with. */
1808 if (code
== TRUTH_ANDIF_EXPR
1809 || code
== TRUTH_ORIF_EXPR
1810 || code
== TRUTH_AND_EXPR
1811 || code
== TRUTH_OR_EXPR
)
1813 /* If one of the operands is zero, we know that the whole
1814 expression evaluates zero. */
1815 if (code
== TRUTH_AND_EXPR
1816 && ((vr0
.type
== VR_RANGE
1817 && integer_zerop (vr0
.min
)
1818 && integer_zerop (vr0
.max
))
1819 || (vr1
.type
== VR_RANGE
1820 && integer_zerop (vr1
.min
)
1821 && integer_zerop (vr1
.max
))))
1824 min
= max
= build_int_cst (TREE_TYPE (expr
), 0);
1826 /* If one of the operands is one, we know that the whole
1827 expression evaluates one. */
1828 else if (code
== TRUTH_OR_EXPR
1829 && ((vr0
.type
== VR_RANGE
1830 && integer_onep (vr0
.min
)
1831 && integer_onep (vr0
.max
))
1832 || (vr1
.type
== VR_RANGE
1833 && integer_onep (vr1
.min
)
1834 && integer_onep (vr1
.max
))))
1837 min
= max
= build_int_cst (TREE_TYPE (expr
), 1);
1839 else if (vr0
.type
!= VR_VARYING
1840 && vr1
.type
!= VR_VARYING
1841 && vr0
.type
== vr1
.type
1842 && !symbolic_range_p (&vr0
)
1843 && !overflow_infinity_range_p (&vr0
)
1844 && !symbolic_range_p (&vr1
)
1845 && !overflow_infinity_range_p (&vr1
))
1847 /* Boolean expressions cannot be folded with int_const_binop. */
1848 min
= fold_binary (code
, TREE_TYPE (expr
), vr0
.min
, vr1
.min
);
1849 max
= fold_binary (code
, TREE_TYPE (expr
), vr0
.max
, vr1
.max
);
1853 /* The result of a TRUTH_*_EXPR is always true or false. */
1854 set_value_range_to_truthvalue (vr
, TREE_TYPE (expr
));
1858 else if (code
== PLUS_EXPR
1860 || code
== MAX_EXPR
)
1862 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1863 VR_VARYING. It would take more effort to compute a precise
1864 range for such a case. For example, if we have op0 == 1 and
1865 op1 == -1 with their ranges both being ~[0,0], we would have
1866 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1867 Note that we are guaranteed to have vr0.type == vr1.type at
1869 if (code
== PLUS_EXPR
&& vr0
.type
== VR_ANTI_RANGE
)
1871 set_value_range_to_varying (vr
);
1875 /* For operations that make the resulting range directly
1876 proportional to the original ranges, apply the operation to
1877 the same end of each range. */
1878 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1879 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.max
);
1881 else if (code
== MULT_EXPR
1882 || code
== TRUNC_DIV_EXPR
1883 || code
== FLOOR_DIV_EXPR
1884 || code
== CEIL_DIV_EXPR
1885 || code
== EXACT_DIV_EXPR
1886 || code
== ROUND_DIV_EXPR
1887 || code
== RSHIFT_EXPR
)
1893 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1894 drop to VR_VARYING. It would take more effort to compute a
1895 precise range for such a case. For example, if we have
1896 op0 == 65536 and op1 == 65536 with their ranges both being
1897 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1898 we cannot claim that the product is in ~[0,0]. Note that we
1899 are guaranteed to have vr0.type == vr1.type at this
1901 if (code
== MULT_EXPR
1902 && vr0
.type
== VR_ANTI_RANGE
1903 && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0
)))
1905 set_value_range_to_varying (vr
);
1909 /* If we have a RSHIFT_EXPR with any shift values outside [0..prec-1],
1910 then drop to VR_VARYING. Outside of this range we get undefined
1911 behavior from the shift operation. We cannot even trust
1912 SHIFT_COUNT_TRUNCATED at this stage, because that applies to rtl
1913 shifts, and the operation at the tree level may be widened. */
1914 if (code
== RSHIFT_EXPR
)
1916 if (vr1
.type
== VR_ANTI_RANGE
1917 || !vrp_expr_computes_nonnegative (op1
, &sop
)
1919 (build_int_cst (TREE_TYPE (vr1
.max
),
1920 TYPE_PRECISION (TREE_TYPE (expr
)) - 1),
1923 set_value_range_to_varying (vr
);
1928 /* Multiplications and divisions are a bit tricky to handle,
1929 depending on the mix of signs we have in the two ranges, we
1930 need to operate on different values to get the minimum and
1931 maximum values for the new range. One approach is to figure
1932 out all the variations of range combinations and do the
1935 However, this involves several calls to compare_values and it
1936 is pretty convoluted. It's simpler to do the 4 operations
1937 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1938 MAX1) and then figure the smallest and largest values to form
1941 /* Divisions by zero result in a VARYING value. */
1942 else if (code
!= MULT_EXPR
1943 && (vr0
.type
== VR_ANTI_RANGE
|| range_includes_zero_p (&vr1
)))
1945 set_value_range_to_varying (vr
);
1949 /* Compute the 4 cross operations. */
1951 val
[0] = vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1952 if (val
[0] == NULL_TREE
)
1955 if (vr1
.max
== vr1
.min
)
1959 val
[1] = vrp_int_const_binop (code
, vr0
.min
, vr1
.max
);
1960 if (val
[1] == NULL_TREE
)
1964 if (vr0
.max
== vr0
.min
)
1968 val
[2] = vrp_int_const_binop (code
, vr0
.max
, vr1
.min
);
1969 if (val
[2] == NULL_TREE
)
1973 if (vr0
.min
== vr0
.max
|| vr1
.min
== vr1
.max
)
1977 val
[3] = vrp_int_const_binop (code
, vr0
.max
, vr1
.max
);
1978 if (val
[3] == NULL_TREE
)
1984 set_value_range_to_varying (vr
);
1988 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1992 for (i
= 1; i
< 4; i
++)
1994 if (!is_gimple_min_invariant (min
)
1995 || (TREE_OVERFLOW (min
) && !is_overflow_infinity (min
))
1996 || !is_gimple_min_invariant (max
)
1997 || (TREE_OVERFLOW (max
) && !is_overflow_infinity (max
)))
2002 if (!is_gimple_min_invariant (val
[i
])
2003 || (TREE_OVERFLOW (val
[i
])
2004 && !is_overflow_infinity (val
[i
])))
2006 /* If we found an overflowed value, set MIN and MAX
2007 to it so that we set the resulting range to
2013 if (compare_values (val
[i
], min
) == -1)
2016 if (compare_values (val
[i
], max
) == 1)
2021 else if (code
== MINUS_EXPR
)
2023 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
2024 VR_VARYING. It would take more effort to compute a precise
2025 range for such a case. For example, if we have op0 == 1 and
2026 op1 == 1 with their ranges both being ~[0,0], we would have
2027 op0 - op1 == 0, so we cannot claim that the difference is in
2028 ~[0,0]. Note that we are guaranteed to have
2029 vr0.type == vr1.type at this point. */
2030 if (vr0
.type
== VR_ANTI_RANGE
)
2032 set_value_range_to_varying (vr
);
2036 /* For MINUS_EXPR, apply the operation to the opposite ends of
2038 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.max
);
2039 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.min
);
2041 else if (code
== BIT_AND_EXPR
)
2043 if (vr0
.type
== VR_RANGE
2044 && vr0
.min
== vr0
.max
2045 && TREE_CODE (vr0
.max
) == INTEGER_CST
2046 && !TREE_OVERFLOW (vr0
.max
)
2047 && tree_int_cst_sgn (vr0
.max
) >= 0)
2049 min
= build_int_cst (TREE_TYPE (expr
), 0);
2052 else if (vr1
.type
== VR_RANGE
2053 && vr1
.min
== vr1
.max
2054 && TREE_CODE (vr1
.max
) == INTEGER_CST
2055 && !TREE_OVERFLOW (vr1
.max
)
2056 && tree_int_cst_sgn (vr1
.max
) >= 0)
2059 min
= build_int_cst (TREE_TYPE (expr
), 0);
2064 set_value_range_to_varying (vr
);
2071 /* If either MIN or MAX overflowed, then set the resulting range to
2072 VARYING. But we do accept an overflow infinity
2074 if (min
== NULL_TREE
2075 || !is_gimple_min_invariant (min
)
2076 || (TREE_OVERFLOW (min
) && !is_overflow_infinity (min
))
2078 || !is_gimple_min_invariant (max
)
2079 || (TREE_OVERFLOW (max
) && !is_overflow_infinity (max
)))
2081 set_value_range_to_varying (vr
);
2087 2) [-INF, +-INF(OVF)]
2088 3) [+-INF(OVF), +INF]
2089 4) [+-INF(OVF), +-INF(OVF)]
2090 We learn nothing when we have INF and INF(OVF) on both sides.
2091 Note that we do accept [-INF, -INF] and [+INF, +INF] without
2093 if ((vrp_val_is_min (min
) || is_overflow_infinity (min
))
2094 && (vrp_val_is_max (max
) || is_overflow_infinity (max
)))
2096 set_value_range_to_varying (vr
);
2100 cmp
= compare_values (min
, max
);
2101 if (cmp
== -2 || cmp
== 1)
2103 /* If the new range has its limits swapped around (MIN > MAX),
2104 then the operation caused one of them to wrap around, mark
2105 the new range VARYING. */
2106 set_value_range_to_varying (vr
);
2109 set_value_range (vr
, type
, min
, max
, NULL
);
2113 /* Extract range information from a unary expression EXPR based on
2114 the range of its operand and the expression code. */
2117 extract_range_from_unary_expr (value_range_t
*vr
, tree expr
)
2119 enum tree_code code
= TREE_CODE (expr
);
2122 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
2124 /* Refuse to operate on certain unary expressions for which we
2125 cannot easily determine a resulting range. */
2126 if (code
== FIX_TRUNC_EXPR
2127 || code
== FLOAT_EXPR
2128 || code
== BIT_NOT_EXPR
2129 || code
== NON_LVALUE_EXPR
2130 || code
== CONJ_EXPR
)
2132 set_value_range_to_varying (vr
);
2136 /* Get value ranges for the operand. For constant operands, create
2137 a new value range with the operand to simplify processing. */
2138 op0
= TREE_OPERAND (expr
, 0);
2139 if (TREE_CODE (op0
) == SSA_NAME
)
2140 vr0
= *(get_value_range (op0
));
2141 else if (is_gimple_min_invariant (op0
))
2142 set_value_range_to_value (&vr0
, op0
, NULL
);
2144 set_value_range_to_varying (&vr0
);
2146 /* If VR0 is UNDEFINED, so is the result. */
2147 if (vr0
.type
== VR_UNDEFINED
)
2149 set_value_range_to_undefined (vr
);
2153 /* Refuse to operate on symbolic ranges, or if neither operand is
2154 a pointer or integral type. */
2155 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
2156 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
2157 || (vr0
.type
!= VR_VARYING
2158 && symbolic_range_p (&vr0
)))
2160 set_value_range_to_varying (vr
);
2164 /* If the expression involves pointers, we are only interested in
2165 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
2166 if (POINTER_TYPE_P (TREE_TYPE (expr
)) || POINTER_TYPE_P (TREE_TYPE (op0
)))
2171 if (range_is_nonnull (&vr0
)
2172 || (tree_expr_nonzero_warnv_p (expr
, &sop
)
2174 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
2175 else if (range_is_null (&vr0
))
2176 set_value_range_to_null (vr
, TREE_TYPE (expr
));
2178 set_value_range_to_varying (vr
);
2183 /* Handle unary expressions on integer ranges. */
2184 if (code
== NOP_EXPR
|| code
== CONVERT_EXPR
)
2186 tree inner_type
= TREE_TYPE (op0
);
2187 tree outer_type
= TREE_TYPE (expr
);
2189 /* If VR0 represents a simple range, then try to convert
2190 the min and max values for the range to the same type
2191 as OUTER_TYPE. If the results compare equal to VR0's
2192 min and max values and the new min is still less than
2193 or equal to the new max, then we can safely use the newly
2194 computed range for EXPR. This allows us to compute
2195 accurate ranges through many casts. */
2196 if ((vr0
.type
== VR_RANGE
2197 && !overflow_infinity_range_p (&vr0
))
2198 || (vr0
.type
== VR_VARYING
2199 && TYPE_PRECISION (outer_type
) > TYPE_PRECISION (inner_type
)))
2201 tree new_min
, new_max
, orig_min
, orig_max
;
2203 /* Convert the input operand min/max to OUTER_TYPE. If
2204 the input has no range information, then use the min/max
2205 for the input's type. */
2206 if (vr0
.type
== VR_RANGE
)
2213 orig_min
= TYPE_MIN_VALUE (inner_type
);
2214 orig_max
= TYPE_MAX_VALUE (inner_type
);
2217 new_min
= fold_convert (outer_type
, orig_min
);
2218 new_max
= fold_convert (outer_type
, orig_max
);
2220 /* Verify the new min/max values are gimple values and
2221 that they compare equal to the original input's
2223 if (is_gimple_val (new_min
)
2224 && is_gimple_val (new_max
)
2225 && tree_int_cst_equal (new_min
, orig_min
)
2226 && tree_int_cst_equal (new_max
, orig_max
)
2227 && (!is_overflow_infinity (new_min
)
2228 || !is_overflow_infinity (new_max
))
2229 && (cmp
= compare_values (new_min
, new_max
)) <= 0
2232 set_value_range (vr
, VR_RANGE
, new_min
, new_max
, vr
->equiv
);
2237 /* When converting types of different sizes, set the result to
2238 VARYING. Things like sign extensions and precision loss may
2239 change the range. For instance, if x_3 is of type 'long long
2240 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
2241 is impossible to know at compile time whether y_5 will be
2243 if (TYPE_SIZE (inner_type
) != TYPE_SIZE (outer_type
)
2244 || TYPE_PRECISION (inner_type
) != TYPE_PRECISION (outer_type
))
2246 set_value_range_to_varying (vr
);
2251 /* Conversion of a VR_VARYING value to a wider type can result
2252 in a usable range. So wait until after we've handled conversions
2253 before dropping the result to VR_VARYING if we had a source
2254 operand that is VR_VARYING. */
2255 if (vr0
.type
== VR_VARYING
)
2257 set_value_range_to_varying (vr
);
2261 /* Apply the operation to each end of the range and see what we end
2263 if (code
== NEGATE_EXPR
2264 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
2266 /* NEGATE_EXPR flips the range around. We need to treat
2267 TYPE_MIN_VALUE specially. */
2268 if (is_positive_overflow_infinity (vr0
.max
))
2269 min
= negative_overflow_infinity (TREE_TYPE (expr
));
2270 else if (is_negative_overflow_infinity (vr0
.max
))
2271 min
= positive_overflow_infinity (TREE_TYPE (expr
));
2272 else if (!vrp_val_is_min (vr0
.max
))
2273 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
2274 else if (needs_overflow_infinity (TREE_TYPE (expr
)))
2276 if (supports_overflow_infinity (TREE_TYPE (expr
))
2277 && !is_overflow_infinity (vr0
.min
)
2278 && !vrp_val_is_min (vr0
.min
))
2279 min
= positive_overflow_infinity (TREE_TYPE (expr
));
2282 set_value_range_to_varying (vr
);
2287 min
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
2289 if (is_positive_overflow_infinity (vr0
.min
))
2290 max
= negative_overflow_infinity (TREE_TYPE (expr
));
2291 else if (is_negative_overflow_infinity (vr0
.min
))
2292 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2293 else if (!vrp_val_is_min (vr0
.min
))
2294 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
2295 else if (needs_overflow_infinity (TREE_TYPE (expr
)))
2297 if (supports_overflow_infinity (TREE_TYPE (expr
)))
2298 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2301 set_value_range_to_varying (vr
);
2306 max
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
2308 else if (code
== NEGATE_EXPR
2309 && TYPE_UNSIGNED (TREE_TYPE (expr
)))
2311 if (!range_includes_zero_p (&vr0
))
2313 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
2314 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
2318 if (range_is_null (&vr0
))
2319 set_value_range_to_null (vr
, TREE_TYPE (expr
));
2321 set_value_range_to_varying (vr
);
2325 else if (code
== ABS_EXPR
2326 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
2328 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
2330 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (expr
))
2331 && ((vr0
.type
== VR_RANGE
2332 && vrp_val_is_min (vr0
.min
))
2333 || (vr0
.type
== VR_ANTI_RANGE
2334 && !vrp_val_is_min (vr0
.min
)
2335 && !range_includes_zero_p (&vr0
))))
2337 set_value_range_to_varying (vr
);
2341 /* ABS_EXPR may flip the range around, if the original range
2342 included negative values. */
2343 if (is_overflow_infinity (vr0
.min
))
2344 min
= positive_overflow_infinity (TREE_TYPE (expr
));
2345 else if (!vrp_val_is_min (vr0
.min
))
2346 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
2347 else if (!needs_overflow_infinity (TREE_TYPE (expr
)))
2348 min
= TYPE_MAX_VALUE (TREE_TYPE (expr
));
2349 else if (supports_overflow_infinity (TREE_TYPE (expr
)))
2350 min
= positive_overflow_infinity (TREE_TYPE (expr
));
2353 set_value_range_to_varying (vr
);
2357 if (is_overflow_infinity (vr0
.max
))
2358 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2359 else if (!vrp_val_is_min (vr0
.max
))
2360 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
2361 else if (!needs_overflow_infinity (TREE_TYPE (expr
)))
2362 max
= TYPE_MAX_VALUE (TREE_TYPE (expr
));
2363 else if (supports_overflow_infinity (TREE_TYPE (expr
)))
2364 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2367 set_value_range_to_varying (vr
);
2371 cmp
= compare_values (min
, max
);
2373 /* If a VR_ANTI_RANGEs contains zero, then we have
2374 ~[-INF, min(MIN, MAX)]. */
2375 if (vr0
.type
== VR_ANTI_RANGE
)
2377 if (range_includes_zero_p (&vr0
))
2379 /* Take the lower of the two values. */
2383 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
2384 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
2385 flag_wrapv is set and the original anti-range doesn't include
2386 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
2387 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr
)))
2389 tree type_min_value
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
2391 min
= (vr0
.min
!= type_min_value
2392 ? int_const_binop (PLUS_EXPR
, type_min_value
,
2393 integer_one_node
, 0)
2398 if (overflow_infinity_range_p (&vr0
))
2399 min
= negative_overflow_infinity (TREE_TYPE (expr
));
2401 min
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
2406 /* All else has failed, so create the range [0, INF], even for
2407 flag_wrapv since TYPE_MIN_VALUE is in the original
2409 vr0
.type
= VR_RANGE
;
2410 min
= build_int_cst (TREE_TYPE (expr
), 0);
2411 if (needs_overflow_infinity (TREE_TYPE (expr
)))
2413 if (supports_overflow_infinity (TREE_TYPE (expr
)))
2414 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2417 set_value_range_to_varying (vr
);
2422 max
= TYPE_MAX_VALUE (TREE_TYPE (expr
));
2426 /* If the range contains zero then we know that the minimum value in the
2427 range will be zero. */
2428 else if (range_includes_zero_p (&vr0
))
2432 min
= build_int_cst (TREE_TYPE (expr
), 0);
2436 /* If the range was reversed, swap MIN and MAX. */
2447 /* Otherwise, operate on each end of the range. */
2448 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
2449 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
2451 if (needs_overflow_infinity (TREE_TYPE (expr
)))
2453 gcc_assert (code
!= NEGATE_EXPR
&& code
!= ABS_EXPR
);
2455 /* If both sides have overflowed, we don't know
2457 if ((is_overflow_infinity (vr0
.min
)
2458 || TREE_OVERFLOW (min
))
2459 && (is_overflow_infinity (vr0
.max
)
2460 || TREE_OVERFLOW (max
)))
2462 set_value_range_to_varying (vr
);
2466 if (is_overflow_infinity (vr0
.min
))
2468 else if (TREE_OVERFLOW (min
))
2470 if (supports_overflow_infinity (TREE_TYPE (expr
)))
2471 min
= (tree_int_cst_sgn (min
) >= 0
2472 ? positive_overflow_infinity (TREE_TYPE (min
))
2473 : negative_overflow_infinity (TREE_TYPE (min
)));
2476 set_value_range_to_varying (vr
);
2481 if (is_overflow_infinity (vr0
.max
))
2483 else if (TREE_OVERFLOW (max
))
2485 if (supports_overflow_infinity (TREE_TYPE (expr
)))
2486 max
= (tree_int_cst_sgn (max
) >= 0
2487 ? positive_overflow_infinity (TREE_TYPE (max
))
2488 : negative_overflow_infinity (TREE_TYPE (max
)));
2491 set_value_range_to_varying (vr
);
2498 cmp
= compare_values (min
, max
);
2499 if (cmp
== -2 || cmp
== 1)
2501 /* If the new range has its limits swapped around (MIN > MAX),
2502 then the operation caused one of them to wrap around, mark
2503 the new range VARYING. */
2504 set_value_range_to_varying (vr
);
2507 set_value_range (vr
, vr0
.type
, min
, max
, NULL
);
2511 /* Extract range information from a conditional expression EXPR based on
2512 the ranges of each of its operands and the expression code. */
2515 extract_range_from_cond_expr (value_range_t
*vr
, tree expr
)
2518 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
2519 value_range_t vr1
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
2521 /* Get value ranges for each operand. For constant operands, create
2522 a new value range with the operand to simplify processing. */
2523 op0
= COND_EXPR_THEN (expr
);
2524 if (TREE_CODE (op0
) == SSA_NAME
)
2525 vr0
= *(get_value_range (op0
));
2526 else if (is_gimple_min_invariant (op0
))
2527 set_value_range_to_value (&vr0
, op0
, NULL
);
2529 set_value_range_to_varying (&vr0
);
2531 op1
= COND_EXPR_ELSE (expr
);
2532 if (TREE_CODE (op1
) == SSA_NAME
)
2533 vr1
= *(get_value_range (op1
));
2534 else if (is_gimple_min_invariant (op1
))
2535 set_value_range_to_value (&vr1
, op1
, NULL
);
2537 set_value_range_to_varying (&vr1
);
2539 /* The resulting value range is the union of the operand ranges */
2540 vrp_meet (&vr0
, &vr1
);
2541 copy_value_range (vr
, &vr0
);
2545 /* Extract range information from a comparison expression EXPR based
2546 on the range of its operand and the expression code. */
2549 extract_range_from_comparison (value_range_t
*vr
, tree expr
)
2552 tree val
= vrp_evaluate_conditional_warnv (expr
, false, &sop
);
2554 /* A disadvantage of using a special infinity as an overflow
2555 representation is that we lose the ability to record overflow
2556 when we don't have an infinity. So we have to ignore a result
2557 which relies on overflow. */
2559 if (val
&& !is_overflow_infinity (val
) && !sop
)
2561 /* Since this expression was found on the RHS of an assignment,
2562 its type may be different from _Bool. Convert VAL to EXPR's
2564 val
= fold_convert (TREE_TYPE (expr
), val
);
2565 if (is_gimple_min_invariant (val
))
2566 set_value_range_to_value (vr
, val
, vr
->equiv
);
2568 set_value_range (vr
, VR_RANGE
, val
, val
, vr
->equiv
);
2571 /* The result of a comparison is always true or false. */
2572 set_value_range_to_truthvalue (vr
, TREE_TYPE (expr
));
2576 /* Try to compute a useful range out of expression EXPR and store it
2580 extract_range_from_expr (value_range_t
*vr
, tree expr
)
2582 enum tree_code code
= TREE_CODE (expr
);
2584 if (code
== ASSERT_EXPR
)
2585 extract_range_from_assert (vr
, expr
);
2586 else if (code
== SSA_NAME
)
2587 extract_range_from_ssa_name (vr
, expr
);
2588 else if (TREE_CODE_CLASS (code
) == tcc_binary
2589 || code
== TRUTH_ANDIF_EXPR
2590 || code
== TRUTH_ORIF_EXPR
2591 || code
== TRUTH_AND_EXPR
2592 || code
== TRUTH_OR_EXPR
2593 || code
== TRUTH_XOR_EXPR
)
2594 extract_range_from_binary_expr (vr
, expr
);
2595 else if (TREE_CODE_CLASS (code
) == tcc_unary
)
2596 extract_range_from_unary_expr (vr
, expr
);
2597 else if (code
== COND_EXPR
)
2598 extract_range_from_cond_expr (vr
, expr
);
2599 else if (TREE_CODE_CLASS (code
) == tcc_comparison
)
2600 extract_range_from_comparison (vr
, expr
);
2601 else if (is_gimple_min_invariant (expr
))
2602 set_value_range_to_value (vr
, expr
, NULL
);
2604 set_value_range_to_varying (vr
);
2606 /* If we got a varying range from the tests above, try a final
2607 time to derive a nonnegative or nonzero range. This time
2608 relying primarily on generic routines in fold in conjunction
2610 if (vr
->type
== VR_VARYING
)
2614 if (INTEGRAL_TYPE_P (TREE_TYPE (expr
))
2615 && vrp_expr_computes_nonnegative (expr
, &sop
))
2616 set_value_range_to_nonnegative (vr
, TREE_TYPE (expr
),
2617 sop
|| is_overflow_infinity (expr
));
2618 else if (vrp_expr_computes_nonzero (expr
, &sop
)
2620 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
2624 /* Given a range VR, a LOOP and a variable VAR, determine whether it
2625 would be profitable to adjust VR using scalar evolution information
2626 for VAR. If so, update VR with the new limits. */
2629 adjust_range_with_scev (value_range_t
*vr
, struct loop
*loop
, tree stmt
,
2632 tree init
, step
, chrec
, tmin
, tmax
, min
, max
, type
;
2633 enum ev_direction dir
;
2635 /* TODO. Don't adjust anti-ranges. An anti-range may provide
2636 better opportunities than a regular range, but I'm not sure. */
2637 if (vr
->type
== VR_ANTI_RANGE
)
2640 chrec
= instantiate_parameters (loop
, analyze_scalar_evolution (loop
, var
));
2642 /* Like in PR19590, scev can return a constant function. */
2643 if (is_gimple_min_invariant (chrec
))
2645 set_value_range (vr
, VR_RANGE
, chrec
, chrec
, vr
->equiv
);
2649 if (TREE_CODE (chrec
) != POLYNOMIAL_CHREC
)
2652 init
= initial_condition_in_loop_num (chrec
, loop
->num
);
2653 step
= evolution_part_in_loop_num (chrec
, loop
->num
);
2655 /* If STEP is symbolic, we can't know whether INIT will be the
2656 minimum or maximum value in the range. Also, unless INIT is
2657 a simple expression, compare_values and possibly other functions
2658 in tree-vrp won't be able to handle it. */
2659 if (step
== NULL_TREE
2660 || !is_gimple_min_invariant (step
)
2661 || !valid_value_p (init
))
2664 dir
= scev_direction (chrec
);
2665 if (/* Do not adjust ranges if we do not know whether the iv increases
2666 or decreases, ... */
2667 dir
== EV_DIR_UNKNOWN
2668 /* ... or if it may wrap. */
2669 || scev_probably_wraps_p (init
, step
, stmt
, get_chrec_loop (chrec
),
2673 /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of
2674 negative_overflow_infinity and positive_overflow_infinity,
2675 because we have concluded that the loop probably does not
2678 type
= TREE_TYPE (var
);
2679 if (POINTER_TYPE_P (type
) || !TYPE_MIN_VALUE (type
))
2680 tmin
= lower_bound_in_type (type
, type
);
2682 tmin
= TYPE_MIN_VALUE (type
);
2683 if (POINTER_TYPE_P (type
) || !TYPE_MAX_VALUE (type
))
2684 tmax
= upper_bound_in_type (type
, type
);
2686 tmax
= TYPE_MAX_VALUE (type
);
2688 if (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
)
2693 /* For VARYING or UNDEFINED ranges, just about anything we get
2694 from scalar evolutions should be better. */
2696 if (dir
== EV_DIR_DECREASES
)
2701 /* If we would create an invalid range, then just assume we
2702 know absolutely nothing. This may be over-conservative,
2703 but it's clearly safe, and should happen only in unreachable
2704 parts of code, or for invalid programs. */
2705 if (compare_values (min
, max
) == 1)
2708 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
2710 else if (vr
->type
== VR_RANGE
)
2715 if (dir
== EV_DIR_DECREASES
)
2717 /* INIT is the maximum value. If INIT is lower than VR->MAX
2718 but no smaller than VR->MIN, set VR->MAX to INIT. */
2719 if (compare_values (init
, max
) == -1)
2723 /* If we just created an invalid range with the minimum
2724 greater than the maximum, we fail conservatively.
2725 This should happen only in unreachable
2726 parts of code, or for invalid programs. */
2727 if (compare_values (min
, max
) == 1)
2731 /* According to the loop information, the variable does not
2732 overflow. If we think it does, probably because of an
2733 overflow due to arithmetic on a different INF value,
2735 if (is_negative_overflow_infinity (min
))
2740 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2741 if (compare_values (init
, min
) == 1)
2745 /* Again, avoid creating invalid range by failing. */
2746 if (compare_values (min
, max
) == 1)
2750 if (is_positive_overflow_infinity (max
))
2754 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
2758 /* Return true if VAR may overflow at STMT. This checks any available
2759 loop information to see if we can determine that VAR does not
2763 vrp_var_may_overflow (tree var
, tree stmt
)
2766 tree chrec
, init
, step
;
2768 if (current_loops
== NULL
)
2771 l
= loop_containing_stmt (stmt
);
2775 chrec
= instantiate_parameters (l
, analyze_scalar_evolution (l
, var
));
2776 if (TREE_CODE (chrec
) != POLYNOMIAL_CHREC
)
2779 init
= initial_condition_in_loop_num (chrec
, l
->num
);
2780 step
= evolution_part_in_loop_num (chrec
, l
->num
);
2782 if (step
== NULL_TREE
2783 || !is_gimple_min_invariant (step
)
2784 || !valid_value_p (init
))
2787 /* If we get here, we know something useful about VAR based on the
2788 loop information. If it wraps, it may overflow. */
2790 if (scev_probably_wraps_p (init
, step
, stmt
, get_chrec_loop (chrec
),
2794 if (dump_file
&& (dump_flags
& TDF_DETAILS
) != 0)
2796 print_generic_expr (dump_file
, var
, 0);
2797 fprintf (dump_file
, ": loop information indicates does not overflow\n");
2804 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2806 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2807 all the values in the ranges.
2809 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2811 - Return NULL_TREE if it is not always possible to determine the
2812 value of the comparison.
2814 Also set *STRICT_OVERFLOW_P to indicate whether a range with an
2815 overflow infinity was used in the test. */
2819 compare_ranges (enum tree_code comp
, value_range_t
*vr0
, value_range_t
*vr1
,
2820 bool *strict_overflow_p
)
2822 /* VARYING or UNDEFINED ranges cannot be compared. */
2823 if (vr0
->type
== VR_VARYING
2824 || vr0
->type
== VR_UNDEFINED
2825 || vr1
->type
== VR_VARYING
2826 || vr1
->type
== VR_UNDEFINED
)
2829 /* Anti-ranges need to be handled separately. */
2830 if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
2832 /* If both are anti-ranges, then we cannot compute any
2834 if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
2837 /* These comparisons are never statically computable. */
2844 /* Equality can be computed only between a range and an
2845 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2846 if (vr0
->type
== VR_RANGE
)
2848 /* To simplify processing, make VR0 the anti-range. */
2849 value_range_t
*tmp
= vr0
;
2854 gcc_assert (comp
== NE_EXPR
|| comp
== EQ_EXPR
);
2856 if (compare_values_warnv (vr0
->min
, vr1
->min
, strict_overflow_p
) == 0
2857 && compare_values_warnv (vr0
->max
, vr1
->max
, strict_overflow_p
) == 0)
2858 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
2863 if (!usable_range_p (vr0
, strict_overflow_p
)
2864 || !usable_range_p (vr1
, strict_overflow_p
))
2867 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2868 operands around and change the comparison code. */
2869 if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
2872 comp
= (comp
== GT_EXPR
) ? LT_EXPR
: LE_EXPR
;
2878 if (comp
== EQ_EXPR
)
2880 /* Equality may only be computed if both ranges represent
2881 exactly one value. */
2882 if (compare_values_warnv (vr0
->min
, vr0
->max
, strict_overflow_p
) == 0
2883 && compare_values_warnv (vr1
->min
, vr1
->max
, strict_overflow_p
) == 0)
2885 int cmp_min
= compare_values_warnv (vr0
->min
, vr1
->min
,
2887 int cmp_max
= compare_values_warnv (vr0
->max
, vr1
->max
,
2889 if (cmp_min
== 0 && cmp_max
== 0)
2890 return boolean_true_node
;
2891 else if (cmp_min
!= -2 && cmp_max
!= -2)
2892 return boolean_false_node
;
2894 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2895 else if (compare_values_warnv (vr0
->min
, vr1
->max
,
2896 strict_overflow_p
) == 1
2897 || compare_values_warnv (vr1
->min
, vr0
->max
,
2898 strict_overflow_p
) == 1)
2899 return boolean_false_node
;
2903 else if (comp
== NE_EXPR
)
2907 /* If VR0 is completely to the left or completely to the right
2908 of VR1, they are always different. Notice that we need to
2909 make sure that both comparisons yield similar results to
2910 avoid comparing values that cannot be compared at
2912 cmp1
= compare_values_warnv (vr0
->max
, vr1
->min
, strict_overflow_p
);
2913 cmp2
= compare_values_warnv (vr0
->min
, vr1
->max
, strict_overflow_p
);
2914 if ((cmp1
== -1 && cmp2
== -1) || (cmp1
== 1 && cmp2
== 1))
2915 return boolean_true_node
;
2917 /* If VR0 and VR1 represent a single value and are identical,
2919 else if (compare_values_warnv (vr0
->min
, vr0
->max
,
2920 strict_overflow_p
) == 0
2921 && compare_values_warnv (vr1
->min
, vr1
->max
,
2922 strict_overflow_p
) == 0
2923 && compare_values_warnv (vr0
->min
, vr1
->min
,
2924 strict_overflow_p
) == 0
2925 && compare_values_warnv (vr0
->max
, vr1
->max
,
2926 strict_overflow_p
) == 0)
2927 return boolean_false_node
;
2929 /* Otherwise, they may or may not be different. */
2933 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
2937 /* If VR0 is to the left of VR1, return true. */
2938 tst
= compare_values_warnv (vr0
->max
, vr1
->min
, strict_overflow_p
);
2939 if ((comp
== LT_EXPR
&& tst
== -1)
2940 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
2942 if (overflow_infinity_range_p (vr0
)
2943 || overflow_infinity_range_p (vr1
))
2944 *strict_overflow_p
= true;
2945 return boolean_true_node
;
2948 /* If VR0 is to the right of VR1, return false. */
2949 tst
= compare_values_warnv (vr0
->min
, vr1
->max
, strict_overflow_p
);
2950 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
2951 || (comp
== LE_EXPR
&& tst
== 1))
2953 if (overflow_infinity_range_p (vr0
)
2954 || overflow_infinity_range_p (vr1
))
2955 *strict_overflow_p
= true;
2956 return boolean_false_node
;
2959 /* Otherwise, we don't know. */
2967 /* Given a value range VR, a value VAL and a comparison code COMP, return
2968 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2969 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2970 always returns false. Return NULL_TREE if it is not always
2971 possible to determine the value of the comparison. Also set
2972 *STRICT_OVERFLOW_P to indicate whether a range with an overflow
2973 infinity was used in the test. */
2976 compare_range_with_value (enum tree_code comp
, value_range_t
*vr
, tree val
,
2977 bool *strict_overflow_p
)
2979 if (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
)
2982 /* Anti-ranges need to be handled separately. */
2983 if (vr
->type
== VR_ANTI_RANGE
)
2985 /* For anti-ranges, the only predicates that we can compute at
2986 compile time are equality and inequality. */
2993 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2994 if (value_inside_range (val
, vr
) == 1)
2995 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
3000 if (!usable_range_p (vr
, strict_overflow_p
))
3003 if (comp
== EQ_EXPR
)
3005 /* EQ_EXPR may only be computed if VR represents exactly
3007 if (compare_values_warnv (vr
->min
, vr
->max
, strict_overflow_p
) == 0)
3009 int cmp
= compare_values_warnv (vr
->min
, val
, strict_overflow_p
);
3011 return boolean_true_node
;
3012 else if (cmp
== -1 || cmp
== 1 || cmp
== 2)
3013 return boolean_false_node
;
3015 else if (compare_values_warnv (val
, vr
->min
, strict_overflow_p
) == -1
3016 || compare_values_warnv (vr
->max
, val
, strict_overflow_p
) == -1)
3017 return boolean_false_node
;
3021 else if (comp
== NE_EXPR
)
3023 /* If VAL is not inside VR, then they are always different. */
3024 if (compare_values_warnv (vr
->max
, val
, strict_overflow_p
) == -1
3025 || compare_values_warnv (vr
->min
, val
, strict_overflow_p
) == 1)
3026 return boolean_true_node
;
3028 /* If VR represents exactly one value equal to VAL, then return
3030 if (compare_values_warnv (vr
->min
, vr
->max
, strict_overflow_p
) == 0
3031 && compare_values_warnv (vr
->min
, val
, strict_overflow_p
) == 0)
3032 return boolean_false_node
;
3034 /* Otherwise, they may or may not be different. */
3037 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
3041 /* If VR is to the left of VAL, return true. */
3042 tst
= compare_values_warnv (vr
->max
, val
, strict_overflow_p
);
3043 if ((comp
== LT_EXPR
&& tst
== -1)
3044 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
3046 if (overflow_infinity_range_p (vr
))
3047 *strict_overflow_p
= true;
3048 return boolean_true_node
;
3051 /* If VR is to the right of VAL, return false. */
3052 tst
= compare_values_warnv (vr
->min
, val
, strict_overflow_p
);
3053 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
3054 || (comp
== LE_EXPR
&& tst
== 1))
3056 if (overflow_infinity_range_p (vr
))
3057 *strict_overflow_p
= true;
3058 return boolean_false_node
;
3061 /* Otherwise, we don't know. */
3064 else if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
3068 /* If VR is to the right of VAL, return true. */
3069 tst
= compare_values_warnv (vr
->min
, val
, strict_overflow_p
);
3070 if ((comp
== GT_EXPR
&& tst
== 1)
3071 || (comp
== GE_EXPR
&& (tst
== 0 || tst
== 1)))
3073 if (overflow_infinity_range_p (vr
))
3074 *strict_overflow_p
= true;
3075 return boolean_true_node
;
3078 /* If VR is to the left of VAL, return false. */
3079 tst
= compare_values_warnv (vr
->max
, val
, strict_overflow_p
);
3080 if ((comp
== GT_EXPR
&& (tst
== -1 || tst
== 0))
3081 || (comp
== GE_EXPR
&& tst
== -1))
3083 if (overflow_infinity_range_p (vr
))
3084 *strict_overflow_p
= true;
3085 return boolean_false_node
;
3088 /* Otherwise, we don't know. */
3096 /* Debugging dumps. */
3098 void dump_value_range (FILE *, value_range_t
*);
3099 void debug_value_range (value_range_t
*);
3100 void dump_all_value_ranges (FILE *);
3101 void debug_all_value_ranges (void);
3102 void dump_vr_equiv (FILE *, bitmap
);
3103 void debug_vr_equiv (bitmap
);
3106 /* Dump value range VR to FILE. */
3109 dump_value_range (FILE *file
, value_range_t
*vr
)
3112 fprintf (file
, "[]");
3113 else if (vr
->type
== VR_UNDEFINED
)
3114 fprintf (file
, "UNDEFINED");
3115 else if (vr
->type
== VR_RANGE
|| vr
->type
== VR_ANTI_RANGE
)
3117 tree type
= TREE_TYPE (vr
->min
);
3119 fprintf (file
, "%s[", (vr
->type
== VR_ANTI_RANGE
) ? "~" : "");
3121 if (is_negative_overflow_infinity (vr
->min
))
3122 fprintf (file
, "-INF(OVF)");
3123 else if (INTEGRAL_TYPE_P (type
)
3124 && !TYPE_UNSIGNED (type
)
3125 && vrp_val_is_min (vr
->min
))
3126 fprintf (file
, "-INF");
3128 print_generic_expr (file
, vr
->min
, 0);
3130 fprintf (file
, ", ");
3132 if (is_positive_overflow_infinity (vr
->max
))
3133 fprintf (file
, "+INF(OVF)");
3134 else if (INTEGRAL_TYPE_P (type
)
3135 && vrp_val_is_max (vr
->max
))
3136 fprintf (file
, "+INF");
3138 print_generic_expr (file
, vr
->max
, 0);
3140 fprintf (file
, "]");
3147 fprintf (file
, " EQUIVALENCES: { ");
3149 EXECUTE_IF_SET_IN_BITMAP (vr
->equiv
, 0, i
, bi
)
3151 print_generic_expr (file
, ssa_name (i
), 0);
3152 fprintf (file
, " ");
3156 fprintf (file
, "} (%u elements)", c
);
3159 else if (vr
->type
== VR_VARYING
)
3160 fprintf (file
, "VARYING");
3162 fprintf (file
, "INVALID RANGE");
3166 /* Dump value range VR to stderr. */
3169 debug_value_range (value_range_t
*vr
)
3171 dump_value_range (stderr
, vr
);
3172 fprintf (stderr
, "\n");
3176 /* Dump value ranges of all SSA_NAMEs to FILE. */
3179 dump_all_value_ranges (FILE *file
)
3183 for (i
= 0; i
< num_ssa_names
; i
++)
3187 print_generic_expr (file
, ssa_name (i
), 0);
3188 fprintf (file
, ": ");
3189 dump_value_range (file
, vr_value
[i
]);
3190 fprintf (file
, "\n");
3194 fprintf (file
, "\n");
3198 /* Dump all value ranges to stderr. */
3201 debug_all_value_ranges (void)
3203 dump_all_value_ranges (stderr
);
3207 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
3208 create a new SSA name N and return the assertion assignment
3209 'V = ASSERT_EXPR <V, V OP W>'. */
3212 build_assert_expr_for (tree cond
, tree v
)
3216 gcc_assert (TREE_CODE (v
) == SSA_NAME
);
3217 n
= duplicate_ssa_name (v
, NULL_TREE
);
3219 if (COMPARISON_CLASS_P (cond
))
3221 tree a
= build2 (ASSERT_EXPR
, TREE_TYPE (v
), v
, cond
);
3222 assertion
= build_gimple_modify_stmt (n
, a
);
3224 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
)
3226 /* Given !V, build the assignment N = false. */
3227 tree op0
= TREE_OPERAND (cond
, 0);
3228 gcc_assert (op0
== v
);
3229 assertion
= build_gimple_modify_stmt (n
, boolean_false_node
);
3231 else if (TREE_CODE (cond
) == SSA_NAME
)
3233 /* Given V, build the assignment N = true. */
3234 gcc_assert (v
== cond
);
3235 assertion
= build_gimple_modify_stmt (n
, boolean_true_node
);
3240 SSA_NAME_DEF_STMT (n
) = assertion
;
3242 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
3243 operand of the ASSERT_EXPR. Register the new name and the old one
3244 in the replacement table so that we can fix the SSA web after
3245 adding all the ASSERT_EXPRs. */
3246 register_new_name_mapping (n
, v
);
3252 /* Return false if EXPR is a predicate expression involving floating
3256 fp_predicate (tree expr
)
3258 return (COMPARISON_CLASS_P (expr
)
3259 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr
, 0))));
3263 /* If the range of values taken by OP can be inferred after STMT executes,
3264 return the comparison code (COMP_CODE_P) and value (VAL_P) that
3265 describes the inferred range. Return true if a range could be
3269 infer_value_range (tree stmt
, tree op
, enum tree_code
*comp_code_p
, tree
*val_p
)
3272 *comp_code_p
= ERROR_MARK
;
3274 /* Do not attempt to infer anything in names that flow through
3276 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op
))
3279 /* Similarly, don't infer anything from statements that may throw
3281 if (tree_could_throw_p (stmt
))
3284 /* If STMT is the last statement of a basic block with no
3285 successors, there is no point inferring anything about any of its
3286 operands. We would not be able to find a proper insertion point
3287 for the assertion, anyway. */
3288 if (stmt_ends_bb_p (stmt
) && EDGE_COUNT (bb_for_stmt (stmt
)->succs
) == 0)
3291 /* We can only assume that a pointer dereference will yield
3292 non-NULL if -fdelete-null-pointer-checks is enabled. */
3293 if (flag_delete_null_pointer_checks
&& POINTER_TYPE_P (TREE_TYPE (op
)))
3295 unsigned num_uses
, num_loads
, num_stores
;
3297 count_uses_and_derefs (op
, stmt
, &num_uses
, &num_loads
, &num_stores
);
3298 if (num_loads
+ num_stores
> 0)
3300 *val_p
= build_int_cst (TREE_TYPE (op
), 0);
3301 *comp_code_p
= NE_EXPR
;
3310 void dump_asserts_for (FILE *, tree
);
3311 void debug_asserts_for (tree
);
3312 void dump_all_asserts (FILE *);
3313 void debug_all_asserts (void);
3315 /* Dump all the registered assertions for NAME to FILE. */
3318 dump_asserts_for (FILE *file
, tree name
)
3322 fprintf (file
, "Assertions to be inserted for ");
3323 print_generic_expr (file
, name
, 0);
3324 fprintf (file
, "\n");
3326 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
3329 fprintf (file
, "\t");
3330 print_generic_expr (file
, bsi_stmt (loc
->si
), 0);
3331 fprintf (file
, "\n\tBB #%d", loc
->bb
->index
);
3334 fprintf (file
, "\n\tEDGE %d->%d", loc
->e
->src
->index
,
3335 loc
->e
->dest
->index
);
3336 dump_edge_info (file
, loc
->e
, 0);
3338 fprintf (file
, "\n\tPREDICATE: ");
3339 print_generic_expr (file
, name
, 0);
3340 fprintf (file
, " %s ", tree_code_name
[(int)loc
->comp_code
]);
3341 print_generic_expr (file
, loc
->val
, 0);
3342 fprintf (file
, "\n\n");
3346 fprintf (file
, "\n");
3350 /* Dump all the registered assertions for NAME to stderr. */
3353 debug_asserts_for (tree name
)
3355 dump_asserts_for (stderr
, name
);
3359 /* Dump all the registered assertions for all the names to FILE. */
3362 dump_all_asserts (FILE *file
)
3367 fprintf (file
, "\nASSERT_EXPRs to be inserted\n\n");
3368 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
3369 dump_asserts_for (file
, ssa_name (i
));
3370 fprintf (file
, "\n");
3374 /* Dump all the registered assertions for all the names to stderr. */
3377 debug_all_asserts (void)
3379 dump_all_asserts (stderr
);
3383 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
3384 'NAME COMP_CODE VAL' at a location that dominates block BB or
3385 E->DEST, then register this location as a possible insertion point
3386 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
3388 BB, E and SI provide the exact insertion point for the new
3389 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
3390 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
3391 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
3392 must not be NULL. */
3395 register_new_assert_for (tree name
,
3396 enum tree_code comp_code
,
3400 block_stmt_iterator si
)
3402 assert_locus_t n
, loc
, last_loc
;
3404 basic_block dest_bb
;
3406 #if defined ENABLE_CHECKING
3407 gcc_assert (bb
== NULL
|| e
== NULL
);
3410 gcc_assert (TREE_CODE (bsi_stmt (si
)) != COND_EXPR
3411 && TREE_CODE (bsi_stmt (si
)) != SWITCH_EXPR
);
3414 /* The new assertion A will be inserted at BB or E. We need to
3415 determine if the new location is dominated by a previously
3416 registered location for A. If we are doing an edge insertion,
3417 assume that A will be inserted at E->DEST. Note that this is not
3420 If E is a critical edge, it will be split. But even if E is
3421 split, the new block will dominate the same set of blocks that
3424 The reverse, however, is not true, blocks dominated by E->DEST
3425 will not be dominated by the new block created to split E. So,
3426 if the insertion location is on a critical edge, we will not use
3427 the new location to move another assertion previously registered
3428 at a block dominated by E->DEST. */
3429 dest_bb
= (bb
) ? bb
: e
->dest
;
3431 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
3432 VAL at a block dominating DEST_BB, then we don't need to insert a new
3433 one. Similarly, if the same assertion already exists at a block
3434 dominated by DEST_BB and the new location is not on a critical
3435 edge, then update the existing location for the assertion (i.e.,
3436 move the assertion up in the dominance tree).
3438 Note, this is implemented as a simple linked list because there
3439 should not be more than a handful of assertions registered per
3440 name. If this becomes a performance problem, a table hashed by
3441 COMP_CODE and VAL could be implemented. */
3442 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
3447 if (loc
->comp_code
== comp_code
3449 || operand_equal_p (loc
->val
, val
, 0)))
3451 /* If the assertion NAME COMP_CODE VAL has already been
3452 registered at a basic block that dominates DEST_BB, then
3453 we don't need to insert the same assertion again. Note
3454 that we don't check strict dominance here to avoid
3455 replicating the same assertion inside the same basic
3456 block more than once (e.g., when a pointer is
3457 dereferenced several times inside a block).
3459 An exception to this rule are edge insertions. If the
3460 new assertion is to be inserted on edge E, then it will
3461 dominate all the other insertions that we may want to
3462 insert in DEST_BB. So, if we are doing an edge
3463 insertion, don't do this dominance check. */
3465 && dominated_by_p (CDI_DOMINATORS
, dest_bb
, loc
->bb
))
3468 /* Otherwise, if E is not a critical edge and DEST_BB
3469 dominates the existing location for the assertion, move
3470 the assertion up in the dominance tree by updating its
3471 location information. */
3472 if ((e
== NULL
|| !EDGE_CRITICAL_P (e
))
3473 && dominated_by_p (CDI_DOMINATORS
, loc
->bb
, dest_bb
))
3482 /* Update the last node of the list and move to the next one. */
3487 /* If we didn't find an assertion already registered for
3488 NAME COMP_CODE VAL, add a new one at the end of the list of
3489 assertions associated with NAME. */
3490 n
= XNEW (struct assert_locus_d
);
3494 n
->comp_code
= comp_code
;
3501 asserts_for
[SSA_NAME_VERSION (name
)] = n
;
3503 bitmap_set_bit (need_assert_for
, SSA_NAME_VERSION (name
));
3506 /* COND is a predicate which uses NAME. Extract a suitable test code
3507 and value and store them into *CODE_P and *VAL_P so the predicate
3508 is normalized to NAME *CODE_P *VAL_P.
3510 If no extraction was possible, return FALSE, otherwise return TRUE.
3512 If INVERT is true, then we invert the result stored into *CODE_P. */
3515 extract_code_and_val_from_cond (tree name
, tree cond
, bool invert
,
3516 enum tree_code
*code_p
, tree
*val_p
)
3518 enum tree_code comp_code
;
3521 /* Predicates may be a single SSA name or NAME OP VAL. */
3524 /* If the predicate is a name, it must be NAME, in which
3525 case we create the predicate NAME == true or
3526 NAME == false accordingly. */
3527 comp_code
= EQ_EXPR
;
3528 val
= invert
? boolean_false_node
: boolean_true_node
;
3532 /* Otherwise, we have a comparison of the form NAME COMP VAL
3533 or VAL COMP NAME. */
3534 if (name
== TREE_OPERAND (cond
, 1))
3536 /* If the predicate is of the form VAL COMP NAME, flip
3537 COMP around because we need to register NAME as the
3538 first operand in the predicate. */
3539 comp_code
= swap_tree_comparison (TREE_CODE (cond
));
3540 val
= TREE_OPERAND (cond
, 0);
3544 /* The comparison is of the form NAME COMP VAL, so the
3545 comparison code remains unchanged. */
3546 comp_code
= TREE_CODE (cond
);
3547 val
= TREE_OPERAND (cond
, 1);
3550 /* Invert the comparison code as necessary. */
3552 comp_code
= invert_tree_comparison (comp_code
, 0);
3554 /* VRP does not handle float types. */
3555 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val
)))
3558 /* Do not register always-false predicates.
3559 FIXME: this works around a limitation in fold() when dealing with
3560 enumerations. Given 'enum { N1, N2 } x;', fold will not
3561 fold 'if (x > N2)' to 'if (0)'. */
3562 if ((comp_code
== GT_EXPR
|| comp_code
== LT_EXPR
)
3563 && INTEGRAL_TYPE_P (TREE_TYPE (val
)))
3565 tree min
= TYPE_MIN_VALUE (TREE_TYPE (val
));
3566 tree max
= TYPE_MAX_VALUE (TREE_TYPE (val
));
3568 if (comp_code
== GT_EXPR
3570 || compare_values (val
, max
) == 0))
3573 if (comp_code
== LT_EXPR
3575 || compare_values (val
, min
) == 0))
3579 *code_p
= comp_code
;
3584 /* OP is an operand of a truth value expression which is known to have
3585 a particular value. Register any asserts for OP and for any
3586 operands in OP's defining statement.
3588 If CODE is EQ_EXPR, then we want to register OP is zero (false),
3589 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
3592 register_edge_assert_for_1 (tree op
, enum tree_code code
,
3593 edge e
, block_stmt_iterator bsi
)
3595 bool retval
= false;
3596 tree op_def
, rhs
, val
;
3598 /* We only care about SSA_NAMEs. */
3599 if (TREE_CODE (op
) != SSA_NAME
)
3602 /* We know that OP will have a zero or nonzero value. If OP is used
3603 more than once go ahead and register an assert for OP.
3605 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
3606 it will always be set for OP (because OP is used in a COND_EXPR in
3608 if (!has_single_use (op
))
3610 val
= build_int_cst (TREE_TYPE (op
), 0);
3611 register_new_assert_for (op
, code
, val
, NULL
, e
, bsi
);
3615 /* Now look at how OP is set. If it's set from a comparison,
3616 a truth operation or some bit operations, then we may be able
3617 to register information about the operands of that assignment. */
3618 op_def
= SSA_NAME_DEF_STMT (op
);
3619 if (TREE_CODE (op_def
) != GIMPLE_MODIFY_STMT
)
3622 rhs
= GIMPLE_STMT_OPERAND (op_def
, 1);
3624 if (COMPARISON_CLASS_P (rhs
))
3626 bool invert
= (code
== EQ_EXPR
? true : false);
3627 tree op0
= TREE_OPERAND (rhs
, 0);
3628 tree op1
= TREE_OPERAND (rhs
, 1);
3630 /* Conditionally register an assert for each SSA_NAME in the
3632 if (TREE_CODE (op0
) == SSA_NAME
3633 && !has_single_use (op0
)
3634 && extract_code_and_val_from_cond (op0
, rhs
,
3635 invert
, &code
, &val
))
3637 register_new_assert_for (op0
, code
, val
, NULL
, e
, bsi
);
3641 /* Similarly for the second operand of the comparison. */
3642 if (TREE_CODE (op1
) == SSA_NAME
3643 && !has_single_use (op1
)
3644 && extract_code_and_val_from_cond (op1
, rhs
,
3645 invert
, &code
, &val
))
3647 register_new_assert_for (op1
, code
, val
, NULL
, e
, bsi
);
3651 else if ((code
== NE_EXPR
3652 && (TREE_CODE (rhs
) == TRUTH_AND_EXPR
3653 || TREE_CODE (rhs
) == BIT_AND_EXPR
))
3655 && (TREE_CODE (rhs
) == TRUTH_OR_EXPR
3656 || TREE_CODE (rhs
) == BIT_IOR_EXPR
)))
3658 /* Recurse on each operand. */
3659 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 0),
3661 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 1),
3664 else if (TREE_CODE (rhs
) == TRUTH_NOT_EXPR
)
3666 /* Recurse, flipping CODE. */
3667 code
= invert_tree_comparison (code
, false);
3668 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 0),
3671 else if (TREE_CODE (rhs
) == SSA_NAME
)
3673 /* Recurse through the copy. */
3674 retval
|= register_edge_assert_for_1 (rhs
, code
, e
, bsi
);
3676 else if (TREE_CODE (rhs
) == NOP_EXPR
3677 || TREE_CODE (rhs
) == CONVERT_EXPR
3678 || TREE_CODE (rhs
) == NON_LVALUE_EXPR
)
3680 /* Recurse through the type conversion. */
3681 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 0),
3688 /* Try to register an edge assertion for SSA name NAME on edge E for
3689 the condition COND contributing to the conditional jump pointed to by SI.
3690 Return true if an assertion for NAME could be registered. */
3693 register_edge_assert_for (tree name
, edge e
, block_stmt_iterator si
, tree cond
)
3696 enum tree_code comp_code
;
3697 bool retval
= false;
3698 bool is_else_edge
= (e
->flags
& EDGE_FALSE_VALUE
) != 0;
3700 /* Do not attempt to infer anything in names that flow through
3702 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name
))
3705 if (!extract_code_and_val_from_cond (name
, cond
, is_else_edge
,
3709 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
3710 reachable from E. */
3711 if (TEST_BIT (found_in_subgraph
, SSA_NAME_VERSION (name
)))
3713 register_new_assert_for (name
, comp_code
, val
, NULL
, e
, si
);
3717 /* If COND is effectively an equality test of an SSA_NAME against
3718 the value zero or one, then we may be able to assert values
3719 for SSA_NAMEs which flow into COND. */
3721 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
3722 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
3723 have nonzero value. */
3724 if (((comp_code
== EQ_EXPR
&& integer_onep (val
))
3725 || (comp_code
== NE_EXPR
&& integer_zerop (val
))))
3727 tree def_stmt
= SSA_NAME_DEF_STMT (name
);
3729 if (TREE_CODE (def_stmt
) == GIMPLE_MODIFY_STMT
3730 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == TRUTH_AND_EXPR
3731 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == BIT_AND_EXPR
))
3733 tree op0
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 0);
3734 tree op1
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 1);
3735 retval
|= register_edge_assert_for_1 (op0
, NE_EXPR
, e
, si
);
3736 retval
|= register_edge_assert_for_1 (op1
, NE_EXPR
, e
, si
);
3740 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
3741 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
3743 if (((comp_code
== EQ_EXPR
&& integer_zerop (val
))
3744 || (comp_code
== NE_EXPR
&& integer_onep (val
))))
3746 tree def_stmt
= SSA_NAME_DEF_STMT (name
);
3748 if (TREE_CODE (def_stmt
) == GIMPLE_MODIFY_STMT
3749 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == TRUTH_OR_EXPR
3750 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == BIT_IOR_EXPR
))
3752 tree op0
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 0);
3753 tree op1
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 1);
3754 retval
|= register_edge_assert_for_1 (op0
, EQ_EXPR
, e
, si
);
3755 retval
|= register_edge_assert_for_1 (op1
, EQ_EXPR
, e
, si
);
3763 static bool find_assert_locations (basic_block bb
);
3765 /* Determine whether the outgoing edges of BB should receive an
3766 ASSERT_EXPR for each of the operands of BB's LAST statement.
3767 The last statement of BB must be a COND_EXPR.
3769 If any of the sub-graphs rooted at BB have an interesting use of
3770 the predicate operands, an assert location node is added to the
3771 list of assertions for the corresponding operands. */
3774 find_conditional_asserts (basic_block bb
, tree last
)
3777 block_stmt_iterator bsi
;
3783 need_assert
= false;
3784 bsi
= bsi_for_stmt (last
);
3786 /* Look for uses of the operands in each of the sub-graphs
3787 rooted at BB. We need to check each of the outgoing edges
3788 separately, so that we know what kind of ASSERT_EXPR to
3790 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3795 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
3796 Otherwise, when we finish traversing each of the sub-graphs, we
3797 won't know whether the variables were found in the sub-graphs or
3798 if they had been found in a block upstream from BB.
3800 This is actually a bad idea is some cases, particularly jump
3801 threading. Consider a CFG like the following:
3811 Assume that one or more operands in the conditional at the
3812 end of block 0 are used in a conditional in block 2, but not
3813 anywhere in block 1. In this case we will not insert any
3814 assert statements in block 1, which may cause us to miss
3815 opportunities to optimize, particularly for jump threading. */
3816 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
3817 RESET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3819 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3820 to determine if any of the operands in the conditional
3821 predicate are used. */
3823 need_assert
|= find_assert_locations (e
->dest
);
3825 /* Register the necessary assertions for each operand in the
3826 conditional predicate. */
3827 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
3828 need_assert
|= register_edge_assert_for (op
, e
, bsi
,
3829 COND_EXPR_COND (last
));
3832 /* Finally, indicate that we have found the operands in the
3834 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
3835 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3840 /* Compare two case labels sorting first by the destination label uid
3841 and then by the case value. */
3844 compare_case_labels (const void *p1
, const void *p2
)
3846 tree case1
= *(tree
*)p1
;
3847 tree case2
= *(tree
*)p2
;
3848 unsigned int uid1
= DECL_UID (CASE_LABEL (case1
));
3849 unsigned int uid2
= DECL_UID (CASE_LABEL (case2
));
3853 else if (uid1
== uid2
)
3855 /* Make sure the default label is first in a group. */
3856 if (!CASE_LOW (case1
))
3858 else if (!CASE_LOW (case2
))
3861 return tree_int_cst_compare (CASE_LOW (case1
), CASE_LOW (case2
));
3867 /* Determine whether the outgoing edges of BB should receive an
3868 ASSERT_EXPR for each of the operands of BB's LAST statement.
3869 The last statement of BB must be a SWITCH_EXPR.
3871 If any of the sub-graphs rooted at BB have an interesting use of
3872 the predicate operands, an assert location node is added to the
3873 list of assertions for the corresponding operands. */
3876 find_switch_asserts (basic_block bb
, tree last
)
3879 block_stmt_iterator bsi
;
3882 tree vec
= SWITCH_LABELS (last
), vec2
;
3883 size_t n
= TREE_VEC_LENGTH (vec
);
3886 need_assert
= false;
3887 bsi
= bsi_for_stmt (last
);
3888 op
= TREE_OPERAND (last
, 0);
3889 if (TREE_CODE (op
) != SSA_NAME
)
3892 /* Build a vector of case labels sorted by destination label. */
3893 vec2
= make_tree_vec (n
);
3894 for (idx
= 0; idx
< n
; ++idx
)
3895 TREE_VEC_ELT (vec2
, idx
) = TREE_VEC_ELT (vec
, idx
);
3896 qsort (&TREE_VEC_ELT (vec2
, 0), n
, sizeof (tree
), compare_case_labels
);
3898 for (idx
= 0; idx
< n
; ++idx
)
3901 tree cl
= TREE_VEC_ELT (vec2
, idx
);
3903 min
= CASE_LOW (cl
);
3904 max
= CASE_HIGH (cl
);
3906 /* If there are multiple case labels with the same destination
3907 we need to combine them to a single value range for the edge. */
3909 && CASE_LABEL (cl
) == CASE_LABEL (TREE_VEC_ELT (vec2
, idx
+ 1)))
3911 /* Skip labels until the last of the group. */
3915 && CASE_LABEL (cl
) == CASE_LABEL (TREE_VEC_ELT (vec2
, idx
)));
3918 /* Pick up the maximum of the case label range. */
3919 if (CASE_HIGH (TREE_VEC_ELT (vec2
, idx
)))
3920 max
= CASE_HIGH (TREE_VEC_ELT (vec2
, idx
));
3922 max
= CASE_LOW (TREE_VEC_ELT (vec2
, idx
));
3925 /* Nothing to do if the range includes the default label until we
3926 can register anti-ranges. */
3927 if (min
== NULL_TREE
)
3930 /* Find the edge to register the assert expr on. */
3931 e
= find_edge (bb
, label_to_block (CASE_LABEL (cl
)));
3933 /* Remove the SWITCH_EXPR operand from the FOUND_IN_SUBGRAPH bitmap.
3934 Otherwise, when we finish traversing each of the sub-graphs, we
3935 won't know whether the variables were found in the sub-graphs or
3936 if they had been found in a block upstream from BB. */
3937 RESET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3939 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3940 to determine if any of the operands in the conditional
3941 predicate are used. */
3943 need_assert
|= find_assert_locations (e
->dest
);
3945 /* Register the necessary assertions for the operand in the
3947 cond
= build2 (max
? GE_EXPR
: EQ_EXPR
, boolean_type_node
,
3948 op
, fold_convert (TREE_TYPE (op
), min
));
3949 need_assert
|= register_edge_assert_for (op
, e
, bsi
, cond
);
3952 cond
= build2 (LE_EXPR
, boolean_type_node
,
3953 op
, fold_convert (TREE_TYPE (op
), max
));
3954 need_assert
|= register_edge_assert_for (op
, e
, bsi
, cond
);
3958 /* Finally, indicate that we have found the operand in the
3960 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3966 /* Traverse all the statements in block BB looking for statements that
3967 may generate useful assertions for the SSA names in their operand.
3968 If a statement produces a useful assertion A for name N_i, then the
3969 list of assertions already generated for N_i is scanned to
3970 determine if A is actually needed.
3972 If N_i already had the assertion A at a location dominating the
3973 current location, then nothing needs to be done. Otherwise, the
3974 new location for A is recorded instead.
3976 1- For every statement S in BB, all the variables used by S are
3977 added to bitmap FOUND_IN_SUBGRAPH.
3979 2- If statement S uses an operand N in a way that exposes a known
3980 value range for N, then if N was not already generated by an
3981 ASSERT_EXPR, create a new assert location for N. For instance,
3982 if N is a pointer and the statement dereferences it, we can
3983 assume that N is not NULL.
3985 3- COND_EXPRs are a special case of #2. We can derive range
3986 information from the predicate but need to insert different
3987 ASSERT_EXPRs for each of the sub-graphs rooted at the
3988 conditional block. If the last statement of BB is a conditional
3989 expression of the form 'X op Y', then
3991 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
3993 b) If the conditional is the only entry point to the sub-graph
3994 corresponding to the THEN_CLAUSE, recurse into it. On
3995 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
3996 an ASSERT_EXPR is added for the corresponding variable.
3998 c) Repeat step (b) on the ELSE_CLAUSE.
4000 d) Mark X and Y in FOUND_IN_SUBGRAPH.
4009 In this case, an assertion on the THEN clause is useful to
4010 determine that 'a' is always 9 on that edge. However, an assertion
4011 on the ELSE clause would be unnecessary.
4013 4- If BB does not end in a conditional expression, then we recurse
4014 into BB's dominator children.
4016 At the end of the recursive traversal, every SSA name will have a
4017 list of locations where ASSERT_EXPRs should be added. When a new
4018 location for name N is found, it is registered by calling
4019 register_new_assert_for. That function keeps track of all the
4020 registered assertions to prevent adding unnecessary assertions.
4021 For instance, if a pointer P_4 is dereferenced more than once in a
4022 dominator tree, only the location dominating all the dereference of
4023 P_4 will receive an ASSERT_EXPR.
4025 If this function returns true, then it means that there are names
4026 for which we need to generate ASSERT_EXPRs. Those assertions are
4027 inserted by process_assert_insertions. */
4030 find_assert_locations (basic_block bb
)
4032 block_stmt_iterator si
;
4037 if (TEST_BIT (blocks_visited
, bb
->index
))
4040 SET_BIT (blocks_visited
, bb
->index
);
4042 need_assert
= false;
4044 /* Traverse all PHI nodes in BB marking used operands. */
4045 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
4047 use_operand_p arg_p
;
4050 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_USE
)
4052 tree arg
= USE_FROM_PTR (arg_p
);
4053 if (TREE_CODE (arg
) == SSA_NAME
)
4055 gcc_assert (is_gimple_reg (PHI_RESULT (phi
)));
4056 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (arg
));
4061 /* Traverse all the statements in BB marking used names and looking
4062 for statements that may infer assertions for their used operands. */
4064 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
4069 stmt
= bsi_stmt (si
);
4071 /* See if we can derive an assertion for any of STMT's operands. */
4072 FOR_EACH_SSA_TREE_OPERAND (op
, stmt
, i
, SSA_OP_USE
)
4075 enum tree_code comp_code
;
4077 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
4078 the sub-graph of a conditional block, when we return from
4079 this recursive walk, our parent will use the
4080 FOUND_IN_SUBGRAPH bitset to determine if one of the
4081 operands it was looking for was present in the sub-graph. */
4082 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
4084 /* If OP is used in such a way that we can infer a value
4085 range for it, and we don't find a previous assertion for
4086 it, create a new assertion location node for OP. */
4087 if (infer_value_range (stmt
, op
, &comp_code
, &value
))
4089 /* If we are able to infer a nonzero value range for OP,
4090 then walk backwards through the use-def chain to see if OP
4091 was set via a typecast.
4093 If so, then we can also infer a nonzero value range
4094 for the operand of the NOP_EXPR. */
4095 if (comp_code
== NE_EXPR
&& integer_zerop (value
))
4098 tree def_stmt
= SSA_NAME_DEF_STMT (t
);
4100 while (TREE_CODE (def_stmt
) == GIMPLE_MODIFY_STMT
4102 (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == NOP_EXPR
4104 (TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1),
4107 (TREE_TYPE (TREE_OPERAND
4108 (GIMPLE_STMT_OPERAND (def_stmt
,
4111 t
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 0);
4112 def_stmt
= SSA_NAME_DEF_STMT (t
);
4114 /* Note we want to register the assert for the
4115 operand of the NOP_EXPR after SI, not after the
4117 if (! has_single_use (t
))
4119 register_new_assert_for (t
, comp_code
, value
,
4126 /* If OP is used only once, namely in this STMT, don't
4127 bother creating an ASSERT_EXPR for it. Such an
4128 ASSERT_EXPR would do nothing but increase compile time. */
4129 if (!has_single_use (op
))
4131 register_new_assert_for (op
, comp_code
, value
, bb
, NULL
, si
);
4137 /* Remember the last statement of the block. */
4141 /* If BB's last statement is a conditional expression
4142 involving integer operands, recurse into each of the sub-graphs
4143 rooted at BB to determine if we need to add ASSERT_EXPRs. */
4145 && TREE_CODE (last
) == COND_EXPR
4146 && !fp_predicate (COND_EXPR_COND (last
))
4147 && !ZERO_SSA_OPERANDS (last
, SSA_OP_USE
))
4148 need_assert
|= find_conditional_asserts (bb
, last
);
4151 && TREE_CODE (last
) == SWITCH_EXPR
4152 && !ZERO_SSA_OPERANDS (last
, SSA_OP_USE
))
4153 need_assert
|= find_switch_asserts (bb
, last
);
4155 /* Recurse into the dominator children of BB. */
4156 for (son
= first_dom_son (CDI_DOMINATORS
, bb
);
4158 son
= next_dom_son (CDI_DOMINATORS
, son
))
4159 need_assert
|= find_assert_locations (son
);
4165 /* Create an ASSERT_EXPR for NAME and insert it in the location
4166 indicated by LOC. Return true if we made any edge insertions. */
4169 process_assert_insertions_for (tree name
, assert_locus_t loc
)
4171 /* Build the comparison expression NAME_i COMP_CODE VAL. */
4172 tree stmt
, cond
, assert_expr
;
4176 cond
= build2 (loc
->comp_code
, boolean_type_node
, name
, loc
->val
);
4177 assert_expr
= build_assert_expr_for (cond
, name
);
4181 /* We have been asked to insert the assertion on an edge. This
4182 is used only by COND_EXPR and SWITCH_EXPR assertions. */
4183 #if defined ENABLE_CHECKING
4184 gcc_assert (TREE_CODE (bsi_stmt (loc
->si
)) == COND_EXPR
4185 || TREE_CODE (bsi_stmt (loc
->si
)) == SWITCH_EXPR
);
4188 bsi_insert_on_edge (loc
->e
, assert_expr
);
4192 /* Otherwise, we can insert right after LOC->SI iff the
4193 statement must not be the last statement in the block. */
4194 stmt
= bsi_stmt (loc
->si
);
4195 if (!stmt_ends_bb_p (stmt
))
4197 bsi_insert_after (&loc
->si
, assert_expr
, BSI_SAME_STMT
);
4201 /* If STMT must be the last statement in BB, we can only insert new
4202 assertions on the non-abnormal edge out of BB. Note that since
4203 STMT is not control flow, there may only be one non-abnormal edge
4205 FOR_EACH_EDGE (e
, ei
, loc
->bb
->succs
)
4206 if (!(e
->flags
& EDGE_ABNORMAL
))
4208 bsi_insert_on_edge (e
, assert_expr
);
4216 /* Process all the insertions registered for every name N_i registered
4217 in NEED_ASSERT_FOR. The list of assertions to be inserted are
4218 found in ASSERTS_FOR[i]. */
4221 process_assert_insertions (void)
4225 bool update_edges_p
= false;
4226 int num_asserts
= 0;
4228 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4229 dump_all_asserts (dump_file
);
4231 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
4233 assert_locus_t loc
= asserts_for
[i
];
4238 assert_locus_t next
= loc
->next
;
4239 update_edges_p
|= process_assert_insertions_for (ssa_name (i
), loc
);
4247 bsi_commit_edge_inserts ();
4249 if (dump_file
&& (dump_flags
& TDF_STATS
))
4250 fprintf (dump_file
, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
4255 /* Traverse the flowgraph looking for conditional jumps to insert range
4256 expressions. These range expressions are meant to provide information
4257 to optimizations that need to reason in terms of value ranges. They
4258 will not be expanded into RTL. For instance, given:
4267 this pass will transform the code into:
4273 x = ASSERT_EXPR <x, x < y>
4278 y = ASSERT_EXPR <y, x <= y>
4282 The idea is that once copy and constant propagation have run, other
4283 optimizations will be able to determine what ranges of values can 'x'
4284 take in different paths of the code, simply by checking the reaching
4285 definition of 'x'. */
4288 insert_range_assertions (void)
4294 found_in_subgraph
= sbitmap_alloc (num_ssa_names
);
4295 sbitmap_zero (found_in_subgraph
);
4297 blocks_visited
= sbitmap_alloc (last_basic_block
);
4298 sbitmap_zero (blocks_visited
);
4300 need_assert_for
= BITMAP_ALLOC (NULL
);
4301 asserts_for
= XCNEWVEC (assert_locus_t
, num_ssa_names
);
4303 calculate_dominance_info (CDI_DOMINATORS
);
4305 update_ssa_p
= false;
4306 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
4307 if (find_assert_locations (e
->dest
))
4308 update_ssa_p
= true;
4312 process_assert_insertions ();
4313 update_ssa (TODO_update_ssa_no_phi
);
4316 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4318 fprintf (dump_file
, "\nSSA form after inserting ASSERT_EXPRs\n");
4319 dump_function_to_file (current_function_decl
, dump_file
, dump_flags
);
4322 sbitmap_free (found_in_subgraph
);
4324 BITMAP_FREE (need_assert_for
);
4327 /* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays
4328 and "struct" hacks. If VRP can determine that the
4329 array subscript is a constant, check if it is outside valid
4330 range. If the array subscript is a RANGE, warn if it is
4331 non-overlapping with valid range.
4332 IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */
4335 check_array_ref (tree ref
, location_t
* locus
, bool ignore_off_by_one
)
4337 value_range_t
* vr
= NULL
;
4338 tree low_sub
, up_sub
;
4339 tree low_bound
, up_bound
= array_ref_up_bound (ref
);
4341 low_sub
= up_sub
= TREE_OPERAND (ref
, 1);
4343 if (!up_bound
|| !locus
|| TREE_NO_WARNING (ref
)
4344 || TREE_CODE (up_bound
) != INTEGER_CST
4345 /* Can not check flexible arrays. */
4346 || (TYPE_SIZE (TREE_TYPE (ref
)) == NULL_TREE
4347 && TYPE_DOMAIN (TREE_TYPE (ref
)) != NULL_TREE
4348 && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (ref
))) == NULL_TREE
)
4349 /* Accesses after the end of arrays of size 0 (gcc
4350 extension) and 1 are likely intentional ("struct
4352 || compare_tree_int (up_bound
, 1) <= 0)
4355 low_bound
= array_ref_low_bound (ref
);
4357 if (TREE_CODE (low_sub
) == SSA_NAME
)
4359 vr
= get_value_range (low_sub
);
4360 if (vr
->type
== VR_RANGE
|| vr
->type
== VR_ANTI_RANGE
)
4362 low_sub
= vr
->type
== VR_RANGE
? vr
->max
: vr
->min
;
4363 up_sub
= vr
->type
== VR_RANGE
? vr
->min
: vr
->max
;
4367 if (vr
&& vr
->type
== VR_ANTI_RANGE
)
4369 if (TREE_CODE (up_sub
) == INTEGER_CST
4370 && tree_int_cst_lt (up_bound
, up_sub
)
4371 && TREE_CODE (low_sub
) == INTEGER_CST
4372 && tree_int_cst_lt (low_sub
, low_bound
))
4374 warning (OPT_Warray_bounds
,
4375 "%Harray subscript is outside array bounds", locus
);
4376 TREE_NO_WARNING (ref
) = 1;
4379 else if (TREE_CODE (up_sub
) == INTEGER_CST
4380 && tree_int_cst_lt (up_bound
, up_sub
)
4381 && !tree_int_cst_equal (up_bound
, up_sub
)
4382 && (!ignore_off_by_one
4383 || !tree_int_cst_equal (int_const_binop (PLUS_EXPR
,
4389 warning (OPT_Warray_bounds
, "%Harray subscript is above array bounds",
4391 TREE_NO_WARNING (ref
) = 1;
4393 else if (TREE_CODE (low_sub
) == INTEGER_CST
4394 && tree_int_cst_lt (low_sub
, low_bound
))
4396 warning (OPT_Warray_bounds
, "%Harray subscript is below array bounds",
4398 TREE_NO_WARNING (ref
) = 1;
4402 /* Searches if the expr T, located at LOCATION computes
4403 address of an ARRAY_REF, and call check_array_ref on it. */
4406 search_for_addr_array(tree t
, location_t
* location
)
4408 while (TREE_CODE (t
) == SSA_NAME
)
4410 t
= SSA_NAME_DEF_STMT (t
);
4411 if (TREE_CODE (t
) != GIMPLE_MODIFY_STMT
)
4413 t
= GIMPLE_STMT_OPERAND (t
, 1);
4417 /* We are only interested in addresses of ARRAY_REF's. */
4418 if (TREE_CODE (t
) != ADDR_EXPR
)
4421 /* Check each ARRAY_REFs in the reference chain. */
4424 if (TREE_CODE (t
) == ARRAY_REF
)
4425 check_array_ref (t
, location
, true /*ignore_off_by_one*/);
4427 t
= TREE_OPERAND(t
,0);
4429 while (handled_component_p (t
));
4432 /* walk_tree() callback that checks if *TP is
4433 an ARRAY_REF inside an ADDR_EXPR (in which an array
4434 subscript one outside the valid range is allowed). Call
4435 check_array_ref for each ARRAY_REF found. The location is
4439 check_array_bounds (tree
*tp
, int *walk_subtree
, void *data
)
4442 tree stmt
= (tree
)data
;
4443 location_t
*location
= EXPR_LOCUS (stmt
);
4445 *walk_subtree
= TRUE
;
4447 if (TREE_CODE (t
) == ARRAY_REF
)
4448 check_array_ref (t
, location
, false /*ignore_off_by_one*/);
4450 if (TREE_CODE (t
) == INDIRECT_REF
4451 || (TREE_CODE (t
) == RETURN_EXPR
&& TREE_OPERAND (t
, 0)))
4452 search_for_addr_array (TREE_OPERAND (t
, 0), location
);
4453 else if (TREE_CODE (t
) == CALL_EXPR
)
4456 call_expr_arg_iterator iter
;
4458 FOR_EACH_CALL_EXPR_ARG (arg
, iter
, t
)
4459 search_for_addr_array (arg
, location
);
4462 if (TREE_CODE (t
) == ADDR_EXPR
)
4463 *walk_subtree
= FALSE
;
4468 /* Walk over all statements of all reachable BBs and call check_array_bounds
4472 check_all_array_refs (void)
4475 block_stmt_iterator si
;
4479 /* Skip bb's that are clearly unreachable. */
4480 if (single_pred_p (bb
))
4482 basic_block pred_bb
= EDGE_PRED (bb
, 0)->src
;
4483 tree ls
= NULL_TREE
;
4485 if (!bsi_end_p (bsi_last (pred_bb
)))
4486 ls
= bsi_stmt (bsi_last (pred_bb
));
4488 if (ls
&& TREE_CODE (ls
) == COND_EXPR
4489 && ((COND_EXPR_COND (ls
) == boolean_false_node
4490 && (EDGE_PRED (bb
, 0)->flags
& EDGE_TRUE_VALUE
))
4491 || (COND_EXPR_COND (ls
) == boolean_true_node
4492 && (EDGE_PRED (bb
, 0)->flags
& EDGE_FALSE_VALUE
))))
4495 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
4496 walk_tree (bsi_stmt_ptr (si
), check_array_bounds
,
4497 bsi_stmt (si
), NULL
);
4501 /* Convert range assertion expressions into the implied copies and
4502 copy propagate away the copies. Doing the trivial copy propagation
4503 here avoids the need to run the full copy propagation pass after
4506 FIXME, this will eventually lead to copy propagation removing the
4507 names that had useful range information attached to them. For
4508 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
4509 then N_i will have the range [3, +INF].
4511 However, by converting the assertion into the implied copy
4512 operation N_i = N_j, we will then copy-propagate N_j into the uses
4513 of N_i and lose the range information. We may want to hold on to
4514 ASSERT_EXPRs a little while longer as the ranges could be used in
4515 things like jump threading.
4517 The problem with keeping ASSERT_EXPRs around is that passes after
4518 VRP need to handle them appropriately.
4520 Another approach would be to make the range information a first
4521 class property of the SSA_NAME so that it can be queried from
4522 any pass. This is made somewhat more complex by the need for
4523 multiple ranges to be associated with one SSA_NAME. */
4526 remove_range_assertions (void)
4529 block_stmt_iterator si
;
4531 /* Note that the BSI iterator bump happens at the bottom of the
4532 loop and no bump is necessary if we're removing the statement
4533 referenced by the current BSI. */
4535 for (si
= bsi_start (bb
); !bsi_end_p (si
);)
4537 tree stmt
= bsi_stmt (si
);
4540 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
4541 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt
, 1)) == ASSERT_EXPR
)
4543 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1), var
;
4544 tree cond
= fold (ASSERT_EXPR_COND (rhs
));
4545 use_operand_p use_p
;
4546 imm_use_iterator iter
;
4548 gcc_assert (cond
!= boolean_false_node
);
4550 /* Propagate the RHS into every use of the LHS. */
4551 var
= ASSERT_EXPR_VAR (rhs
);
4552 FOR_EACH_IMM_USE_STMT (use_stmt
, iter
,
4553 GIMPLE_STMT_OPERAND (stmt
, 0))
4554 FOR_EACH_IMM_USE_ON_STMT (use_p
, iter
)
4556 SET_USE (use_p
, var
);
4557 gcc_assert (TREE_CODE (var
) == SSA_NAME
);
4560 /* And finally, remove the copy, it is not needed. */
4561 bsi_remove (&si
, true);
4562 release_defs (stmt
);
4568 sbitmap_free (blocks_visited
);
4572 /* Return true if STMT is interesting for VRP. */
4575 stmt_interesting_for_vrp (tree stmt
)
4577 if (TREE_CODE (stmt
) == PHI_NODE
4578 && is_gimple_reg (PHI_RESULT (stmt
))
4579 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))
4580 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))))
4582 else if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
4584 tree lhs
= GIMPLE_STMT_OPERAND (stmt
, 0);
4585 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
4587 /* In general, assignments with virtual operands are not useful
4588 for deriving ranges, with the obvious exception of calls to
4589 builtin functions. */
4590 if (TREE_CODE (lhs
) == SSA_NAME
4591 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
4592 || POINTER_TYPE_P (TREE_TYPE (lhs
)))
4593 && ((TREE_CODE (rhs
) == CALL_EXPR
4594 && TREE_CODE (CALL_EXPR_FN (rhs
)) == ADDR_EXPR
4595 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs
), 0))
4596 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs
), 0)))
4597 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
)))
4600 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
4607 /* Initialize local data structures for VRP. */
4610 vrp_initialize (void)
4614 vr_value
= XCNEWVEC (value_range_t
*, num_ssa_names
);
4615 vr_phi_edge_counts
= XCNEWVEC (int, num_ssa_names
);
4619 block_stmt_iterator si
;
4622 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
4624 if (!stmt_interesting_for_vrp (phi
))
4626 tree lhs
= PHI_RESULT (phi
);
4627 set_value_range_to_varying (get_value_range (lhs
));
4628 DONT_SIMULATE_AGAIN (phi
) = true;
4631 DONT_SIMULATE_AGAIN (phi
) = false;
4634 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
4636 tree stmt
= bsi_stmt (si
);
4638 if (!stmt_interesting_for_vrp (stmt
))
4642 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, i
, SSA_OP_DEF
)
4643 set_value_range_to_varying (get_value_range (def
));
4644 DONT_SIMULATE_AGAIN (stmt
) = true;
4648 DONT_SIMULATE_AGAIN (stmt
) = false;
4655 /* Visit assignment STMT. If it produces an interesting range, record
4656 the SSA name in *OUTPUT_P. */
4658 static enum ssa_prop_result
4659 vrp_visit_assignment (tree stmt
, tree
*output_p
)
4664 lhs
= GIMPLE_STMT_OPERAND (stmt
, 0);
4665 rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
4667 /* We only keep track of ranges in integral and pointer types. */
4668 if (TREE_CODE (lhs
) == SSA_NAME
4669 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
4670 /* It is valid to have NULL MIN/MAX values on a type. See
4671 build_range_type. */
4672 && TYPE_MIN_VALUE (TREE_TYPE (lhs
))
4673 && TYPE_MAX_VALUE (TREE_TYPE (lhs
)))
4674 || POINTER_TYPE_P (TREE_TYPE (lhs
))))
4677 value_range_t new_vr
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
4679 extract_range_from_expr (&new_vr
, rhs
);
4681 /* If STMT is inside a loop, we may be able to know something
4682 else about the range of LHS by examining scalar evolution
4684 if (current_loops
&& (l
= loop_containing_stmt (stmt
)))
4685 adjust_range_with_scev (&new_vr
, l
, stmt
, lhs
);
4687 if (update_value_range (lhs
, &new_vr
))
4691 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4693 fprintf (dump_file
, "Found new range for ");
4694 print_generic_expr (dump_file
, lhs
, 0);
4695 fprintf (dump_file
, ": ");
4696 dump_value_range (dump_file
, &new_vr
);
4697 fprintf (dump_file
, "\n\n");
4700 if (new_vr
.type
== VR_VARYING
)
4701 return SSA_PROP_VARYING
;
4703 return SSA_PROP_INTERESTING
;
4706 return SSA_PROP_NOT_INTERESTING
;
4709 /* Every other statement produces no useful ranges. */
4710 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
4711 set_value_range_to_varying (get_value_range (def
));
4713 return SSA_PROP_VARYING
;
4716 /* Helper that gets the value range of the SSA_NAME with version I
4717 or a symbolic range containing the SSA_NAME only if the value range
4718 is varying or undefined. */
4720 static inline value_range_t
4721 get_vr_for_comparison (int i
)
4723 value_range_t vr
= *(vr_value
[i
]);
4725 /* If name N_i does not have a valid range, use N_i as its own
4726 range. This allows us to compare against names that may
4727 have N_i in their ranges. */
4728 if (vr
.type
== VR_VARYING
|| vr
.type
== VR_UNDEFINED
)
4731 vr
.min
= ssa_name (i
);
4732 vr
.max
= ssa_name (i
);
4738 /* Compare all the value ranges for names equivalent to VAR with VAL
4739 using comparison code COMP. Return the same value returned by
4740 compare_range_with_value, including the setting of
4741 *STRICT_OVERFLOW_P. */
4744 compare_name_with_value (enum tree_code comp
, tree var
, tree val
,
4745 bool *strict_overflow_p
)
4751 int used_strict_overflow
;
4753 value_range_t equiv_vr
;
4755 /* Get the set of equivalences for VAR. */
4756 e
= get_value_range (var
)->equiv
;
4758 /* Start at -1. Set it to 0 if we do a comparison without relying
4759 on overflow, or 1 if all comparisons rely on overflow. */
4760 used_strict_overflow
= -1;
4762 /* Compare vars' value range with val. */
4763 equiv_vr
= get_vr_for_comparison (SSA_NAME_VERSION (var
));
4765 retval
= compare_range_with_value (comp
, &equiv_vr
, val
, &sop
);
4767 used_strict_overflow
= sop
? 1 : 0;
4769 /* If the equiv set is empty we have done all work we need to do. */
4773 && used_strict_overflow
> 0)
4774 *strict_overflow_p
= true;
4778 EXECUTE_IF_SET_IN_BITMAP (e
, 0, i
, bi
)
4780 equiv_vr
= get_vr_for_comparison (i
);
4782 t
= compare_range_with_value (comp
, &equiv_vr
, val
, &sop
);
4785 /* If we get different answers from different members
4786 of the equivalence set this check must be in a dead
4787 code region. Folding it to a trap representation
4788 would be correct here. For now just return don't-know. */
4798 used_strict_overflow
= 0;
4799 else if (used_strict_overflow
< 0)
4800 used_strict_overflow
= 1;
4805 && used_strict_overflow
> 0)
4806 *strict_overflow_p
= true;
4812 /* Given a comparison code COMP and names N1 and N2, compare all the
4813 ranges equivalent to N1 against all the ranges equivalent to N2
4814 to determine the value of N1 COMP N2. Return the same value
4815 returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate
4816 whether we relied on an overflow infinity in the comparison. */
4820 compare_names (enum tree_code comp
, tree n1
, tree n2
,
4821 bool *strict_overflow_p
)
4825 bitmap_iterator bi1
, bi2
;
4827 int used_strict_overflow
;
4828 static bitmap_obstack
*s_obstack
= NULL
;
4829 static bitmap s_e1
= NULL
, s_e2
= NULL
;
4831 /* Compare the ranges of every name equivalent to N1 against the
4832 ranges of every name equivalent to N2. */
4833 e1
= get_value_range (n1
)->equiv
;
4834 e2
= get_value_range (n2
)->equiv
;
4836 /* Use the fake bitmaps if e1 or e2 are not available. */
4837 if (s_obstack
== NULL
)
4839 s_obstack
= XNEW (bitmap_obstack
);
4840 bitmap_obstack_initialize (s_obstack
);
4841 s_e1
= BITMAP_ALLOC (s_obstack
);
4842 s_e2
= BITMAP_ALLOC (s_obstack
);
4849 /* Add N1 and N2 to their own set of equivalences to avoid
4850 duplicating the body of the loop just to check N1 and N2
4852 bitmap_set_bit (e1
, SSA_NAME_VERSION (n1
));
4853 bitmap_set_bit (e2
, SSA_NAME_VERSION (n2
));
4855 /* If the equivalence sets have a common intersection, then the two
4856 names can be compared without checking their ranges. */
4857 if (bitmap_intersect_p (e1
, e2
))
4859 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
4860 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
4862 return (comp
== EQ_EXPR
|| comp
== GE_EXPR
|| comp
== LE_EXPR
)
4864 : boolean_false_node
;
4867 /* Start at -1. Set it to 0 if we do a comparison without relying
4868 on overflow, or 1 if all comparisons rely on overflow. */
4869 used_strict_overflow
= -1;
4871 /* Otherwise, compare all the equivalent ranges. First, add N1 and
4872 N2 to their own set of equivalences to avoid duplicating the body
4873 of the loop just to check N1 and N2 ranges. */
4874 EXECUTE_IF_SET_IN_BITMAP (e1
, 0, i1
, bi1
)
4876 value_range_t vr1
= get_vr_for_comparison (i1
);
4878 t
= retval
= NULL_TREE
;
4879 EXECUTE_IF_SET_IN_BITMAP (e2
, 0, i2
, bi2
)
4883 value_range_t vr2
= get_vr_for_comparison (i2
);
4885 t
= compare_ranges (comp
, &vr1
, &vr2
, &sop
);
4888 /* If we get different answers from different members
4889 of the equivalence set this check must be in a dead
4890 code region. Folding it to a trap representation
4891 would be correct here. For now just return don't-know. */
4895 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
4896 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
4902 used_strict_overflow
= 0;
4903 else if (used_strict_overflow
< 0)
4904 used_strict_overflow
= 1;
4910 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
4911 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
4912 if (used_strict_overflow
> 0)
4913 *strict_overflow_p
= true;
4918 /* None of the equivalent ranges are useful in computing this
4920 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
4921 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
4926 /* Given a conditional predicate COND, try to determine if COND yields
4927 true or false based on the value ranges of its operands. Return
4928 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
4929 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
4930 NULL if the conditional cannot be evaluated at compile time.
4932 If USE_EQUIV_P is true, the ranges of all the names equivalent with
4933 the operands in COND are used when trying to compute its value.
4934 This is only used during final substitution. During propagation,
4935 we only check the range of each variable and not its equivalents.
4937 Set *STRICT_OVERFLOW_P to indicate whether we relied on an overflow
4938 infinity to produce the result. */
4941 vrp_evaluate_conditional_warnv (tree cond
, bool use_equiv_p
,
4942 bool *strict_overflow_p
)
4944 gcc_assert (TREE_CODE (cond
) == SSA_NAME
4945 || TREE_CODE_CLASS (TREE_CODE (cond
)) == tcc_comparison
);
4947 if (TREE_CODE (cond
) == SSA_NAME
)
4953 retval
= compare_name_with_value (NE_EXPR
, cond
, boolean_false_node
,
4957 value_range_t
*vr
= get_value_range (cond
);
4958 retval
= compare_range_with_value (NE_EXPR
, vr
, boolean_false_node
,
4962 /* If COND has a known boolean range, return it. */
4966 /* Otherwise, if COND has a symbolic range of exactly one value,
4968 vr
= get_value_range (cond
);
4969 if (vr
->type
== VR_RANGE
&& vr
->min
== vr
->max
)
4974 tree op0
= TREE_OPERAND (cond
, 0);
4975 tree op1
= TREE_OPERAND (cond
, 1);
4977 /* We only deal with integral and pointer types. */
4978 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
4979 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
4984 if (TREE_CODE (op0
) == SSA_NAME
&& TREE_CODE (op1
) == SSA_NAME
)
4985 return compare_names (TREE_CODE (cond
), op0
, op1
,
4987 else if (TREE_CODE (op0
) == SSA_NAME
)
4988 return compare_name_with_value (TREE_CODE (cond
), op0
, op1
,
4990 else if (TREE_CODE (op1
) == SSA_NAME
)
4991 return (compare_name_with_value
4992 (swap_tree_comparison (TREE_CODE (cond
)), op1
, op0
,
4993 strict_overflow_p
));
4997 value_range_t
*vr0
, *vr1
;
4999 vr0
= (TREE_CODE (op0
) == SSA_NAME
) ? get_value_range (op0
) : NULL
;
5000 vr1
= (TREE_CODE (op1
) == SSA_NAME
) ? get_value_range (op1
) : NULL
;
5003 return compare_ranges (TREE_CODE (cond
), vr0
, vr1
,
5005 else if (vr0
&& vr1
== NULL
)
5006 return compare_range_with_value (TREE_CODE (cond
), vr0
, op1
,
5008 else if (vr0
== NULL
&& vr1
)
5009 return (compare_range_with_value
5010 (swap_tree_comparison (TREE_CODE (cond
)), vr1
, op0
,
5011 strict_overflow_p
));
5015 /* Anything else cannot be computed statically. */
5019 /* Given COND within STMT, try to simplify it based on value range
5020 information. Return NULL if the conditional can not be evaluated.
5021 The ranges of all the names equivalent with the operands in COND
5022 will be used when trying to compute the value. If the result is
5023 based on undefined signed overflow, issue a warning if
5027 vrp_evaluate_conditional (tree cond
, tree stmt
)
5033 ret
= vrp_evaluate_conditional_warnv (cond
, true, &sop
);
5037 enum warn_strict_overflow_code wc
;
5038 const char* warnmsg
;
5040 if (is_gimple_min_invariant (ret
))
5042 wc
= WARN_STRICT_OVERFLOW_CONDITIONAL
;
5043 warnmsg
= G_("assuming signed overflow does not occur when "
5044 "simplifying conditional to constant");
5048 wc
= WARN_STRICT_OVERFLOW_COMPARISON
;
5049 warnmsg
= G_("assuming signed overflow does not occur when "
5050 "simplifying conditional");
5053 if (issue_strict_overflow_warning (wc
))
5057 if (!EXPR_HAS_LOCATION (stmt
))
5058 locus
= input_location
;
5060 locus
= EXPR_LOCATION (stmt
);
5061 warning (OPT_Wstrict_overflow
, "%H%s", &locus
, warnmsg
);
5069 /* Visit conditional statement STMT. If we can determine which edge
5070 will be taken out of STMT's basic block, record it in
5071 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
5072 SSA_PROP_VARYING. */
5074 static enum ssa_prop_result
5075 vrp_visit_cond_stmt (tree stmt
, edge
*taken_edge_p
)
5080 *taken_edge_p
= NULL
;
5082 /* FIXME. Handle SWITCH_EXPRs. */
5083 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
5084 return SSA_PROP_VARYING
;
5086 cond
= COND_EXPR_COND (stmt
);
5088 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5093 fprintf (dump_file
, "\nVisiting conditional with predicate: ");
5094 print_generic_expr (dump_file
, cond
, 0);
5095 fprintf (dump_file
, "\nWith known ranges\n");
5097 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, i
, SSA_OP_USE
)
5099 fprintf (dump_file
, "\t");
5100 print_generic_expr (dump_file
, use
, 0);
5101 fprintf (dump_file
, ": ");
5102 dump_value_range (dump_file
, vr_value
[SSA_NAME_VERSION (use
)]);
5105 fprintf (dump_file
, "\n");
5108 /* Compute the value of the predicate COND by checking the known
5109 ranges of each of its operands.
5111 Note that we cannot evaluate all the equivalent ranges here
5112 because those ranges may not yet be final and with the current
5113 propagation strategy, we cannot determine when the value ranges
5114 of the names in the equivalence set have changed.
5116 For instance, given the following code fragment
5120 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
5124 Assume that on the first visit to i_14, i_5 has the temporary
5125 range [8, 8] because the second argument to the PHI function is
5126 not yet executable. We derive the range ~[0, 0] for i_14 and the
5127 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
5128 the first time, since i_14 is equivalent to the range [8, 8], we
5129 determine that the predicate is always false.
5131 On the next round of propagation, i_13 is determined to be
5132 VARYING, which causes i_5 to drop down to VARYING. So, another
5133 visit to i_14 is scheduled. In this second visit, we compute the
5134 exact same range and equivalence set for i_14, namely ~[0, 0] and
5135 { i_5 }. But we did not have the previous range for i_5
5136 registered, so vrp_visit_assignment thinks that the range for
5137 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
5138 is not visited again, which stops propagation from visiting
5139 statements in the THEN clause of that if().
5141 To properly fix this we would need to keep the previous range
5142 value for the names in the equivalence set. This way we would've
5143 discovered that from one visit to the other i_5 changed from
5144 range [8, 8] to VR_VARYING.
5146 However, fixing this apparent limitation may not be worth the
5147 additional checking. Testing on several code bases (GCC, DLV,
5148 MICO, TRAMP3D and SPEC2000) showed that doing this results in
5149 4 more predicates folded in SPEC. */
5151 val
= vrp_evaluate_conditional_warnv (cond
, false, &sop
);
5155 *taken_edge_p
= find_taken_edge (bb_for_stmt (stmt
), val
);
5158 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5160 "\nIgnoring predicate evaluation because "
5161 "it assumes that signed overflow is undefined");
5166 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5168 fprintf (dump_file
, "\nPredicate evaluates to: ");
5169 if (val
== NULL_TREE
)
5170 fprintf (dump_file
, "DON'T KNOW\n");
5172 print_generic_stmt (dump_file
, val
, 0);
5175 return (*taken_edge_p
) ? SSA_PROP_INTERESTING
: SSA_PROP_VARYING
;
5179 /* Evaluate statement STMT. If the statement produces a useful range,
5180 return SSA_PROP_INTERESTING and record the SSA name with the
5181 interesting range into *OUTPUT_P.
5183 If STMT is a conditional branch and we can determine its truth
5184 value, the taken edge is recorded in *TAKEN_EDGE_P.
5186 If STMT produces a varying value, return SSA_PROP_VARYING. */
5188 static enum ssa_prop_result
5189 vrp_visit_stmt (tree stmt
, edge
*taken_edge_p
, tree
*output_p
)
5195 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5197 fprintf (dump_file
, "\nVisiting statement:\n");
5198 print_generic_stmt (dump_file
, stmt
, dump_flags
);
5199 fprintf (dump_file
, "\n");
5202 ann
= stmt_ann (stmt
);
5203 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
5205 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
5207 /* In general, assignments with virtual operands are not useful
5208 for deriving ranges, with the obvious exception of calls to
5209 builtin functions. */
5210 if ((TREE_CODE (rhs
) == CALL_EXPR
5211 && TREE_CODE (CALL_EXPR_FN (rhs
)) == ADDR_EXPR
5212 && DECL_P (TREE_OPERAND (CALL_EXPR_FN (rhs
), 0))
5213 && DECL_IS_BUILTIN (TREE_OPERAND (CALL_EXPR_FN (rhs
), 0)))
5214 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
5215 return vrp_visit_assignment (stmt
, output_p
);
5217 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
5218 return vrp_visit_cond_stmt (stmt
, taken_edge_p
);
5220 /* All other statements produce nothing of interest for VRP, so mark
5221 their outputs varying and prevent further simulation. */
5222 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
5223 set_value_range_to_varying (get_value_range (def
));
5225 return SSA_PROP_VARYING
;
5229 /* Meet operation for value ranges. Given two value ranges VR0 and
5230 VR1, store in VR0 a range that contains both VR0 and VR1. This
5231 may not be the smallest possible such range. */
5234 vrp_meet (value_range_t
*vr0
, value_range_t
*vr1
)
5236 if (vr0
->type
== VR_UNDEFINED
)
5238 copy_value_range (vr0
, vr1
);
5242 if (vr1
->type
== VR_UNDEFINED
)
5244 /* Nothing to do. VR0 already has the resulting range. */
5248 if (vr0
->type
== VR_VARYING
)
5250 /* Nothing to do. VR0 already has the resulting range. */
5254 if (vr1
->type
== VR_VARYING
)
5256 set_value_range_to_varying (vr0
);
5260 if (vr0
->type
== VR_RANGE
&& vr1
->type
== VR_RANGE
)
5265 /* Compute the convex hull of the ranges. The lower limit of
5266 the new range is the minimum of the two ranges. If they
5267 cannot be compared, then give up. */
5268 cmp
= compare_values (vr0
->min
, vr1
->min
);
5269 if (cmp
== 0 || cmp
== 1)
5276 /* Similarly, the upper limit of the new range is the maximum
5277 of the two ranges. If they cannot be compared, then
5279 cmp
= compare_values (vr0
->max
, vr1
->max
);
5280 if (cmp
== 0 || cmp
== -1)
5287 /* Check for useless ranges. */
5288 if (INTEGRAL_TYPE_P (TREE_TYPE (min
))
5289 && ((vrp_val_is_min (min
) || is_overflow_infinity (min
))
5290 && (vrp_val_is_max (max
) || is_overflow_infinity (max
))))
5293 /* The resulting set of equivalences is the intersection of
5295 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
5296 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
5297 else if (vr0
->equiv
&& !vr1
->equiv
)
5298 bitmap_clear (vr0
->equiv
);
5300 set_value_range (vr0
, vr0
->type
, min
, max
, vr0
->equiv
);
5302 else if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
5304 /* Two anti-ranges meet only if their complements intersect.
5305 Only handle the case of identical ranges. */
5306 if (compare_values (vr0
->min
, vr1
->min
) == 0
5307 && compare_values (vr0
->max
, vr1
->max
) == 0
5308 && compare_values (vr0
->min
, vr0
->max
) == 0)
5310 /* The resulting set of equivalences is the intersection of
5312 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
5313 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
5314 else if (vr0
->equiv
&& !vr1
->equiv
)
5315 bitmap_clear (vr0
->equiv
);
5320 else if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
5322 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
5323 only handle the case where the ranges have an empty intersection.
5324 The result of the meet operation is the anti-range. */
5325 if (!symbolic_range_p (vr0
)
5326 && !symbolic_range_p (vr1
)
5327 && !value_ranges_intersect_p (vr0
, vr1
))
5329 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
5330 set. We need to compute the intersection of the two
5331 equivalence sets. */
5332 if (vr1
->type
== VR_ANTI_RANGE
)
5333 set_value_range (vr0
, vr1
->type
, vr1
->min
, vr1
->max
, vr0
->equiv
);
5335 /* The resulting set of equivalences is the intersection of
5337 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
5338 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
5339 else if (vr0
->equiv
&& !vr1
->equiv
)
5340 bitmap_clear (vr0
->equiv
);
5351 /* Failed to find an efficient meet. Before giving up and setting
5352 the result to VARYING, see if we can at least derive a useful
5353 anti-range. FIXME, all this nonsense about distinguishing
5354 anti-ranges from ranges is necessary because of the odd
5355 semantics of range_includes_zero_p and friends. */
5356 if (!symbolic_range_p (vr0
)
5357 && ((vr0
->type
== VR_RANGE
&& !range_includes_zero_p (vr0
))
5358 || (vr0
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr0
)))
5359 && !symbolic_range_p (vr1
)
5360 && ((vr1
->type
== VR_RANGE
&& !range_includes_zero_p (vr1
))
5361 || (vr1
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr1
))))
5363 set_value_range_to_nonnull (vr0
, TREE_TYPE (vr0
->min
));
5365 /* Since this meet operation did not result from the meeting of
5366 two equivalent names, VR0 cannot have any equivalences. */
5368 bitmap_clear (vr0
->equiv
);
5371 set_value_range_to_varying (vr0
);
5375 /* Visit all arguments for PHI node PHI that flow through executable
5376 edges. If a valid value range can be derived from all the incoming
5377 value ranges, set a new range for the LHS of PHI. */
5379 static enum ssa_prop_result
5380 vrp_visit_phi_node (tree phi
)
5383 tree lhs
= PHI_RESULT (phi
);
5384 value_range_t
*lhs_vr
= get_value_range (lhs
);
5385 value_range_t vr_result
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
5386 int edges
, old_edges
;
5388 copy_value_range (&vr_result
, lhs_vr
);
5390 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5392 fprintf (dump_file
, "\nVisiting PHI node: ");
5393 print_generic_expr (dump_file
, phi
, dump_flags
);
5397 for (i
= 0; i
< PHI_NUM_ARGS (phi
); i
++)
5399 edge e
= PHI_ARG_EDGE (phi
, i
);
5401 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5404 "\n Argument #%d (%d -> %d %sexecutable)\n",
5405 i
, e
->src
->index
, e
->dest
->index
,
5406 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
5409 if (e
->flags
& EDGE_EXECUTABLE
)
5411 tree arg
= PHI_ARG_DEF (phi
, i
);
5412 value_range_t vr_arg
;
5416 if (TREE_CODE (arg
) == SSA_NAME
)
5418 vr_arg
= *(get_value_range (arg
));
5422 if (is_overflow_infinity (arg
))
5424 arg
= copy_node (arg
);
5425 TREE_OVERFLOW (arg
) = 0;
5428 vr_arg
.type
= VR_RANGE
;
5431 vr_arg
.equiv
= NULL
;
5434 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
5436 fprintf (dump_file
, "\t");
5437 print_generic_expr (dump_file
, arg
, dump_flags
);
5438 fprintf (dump_file
, "\n\tValue: ");
5439 dump_value_range (dump_file
, &vr_arg
);
5440 fprintf (dump_file
, "\n");
5443 vrp_meet (&vr_result
, &vr_arg
);
5445 if (vr_result
.type
== VR_VARYING
)
5450 if (vr_result
.type
== VR_VARYING
)
5453 old_edges
= vr_phi_edge_counts
[SSA_NAME_VERSION (lhs
)];
5454 vr_phi_edge_counts
[SSA_NAME_VERSION (lhs
)] = edges
;
5456 /* To prevent infinite iterations in the algorithm, derive ranges
5457 when the new value is slightly bigger or smaller than the
5458 previous one. We don't do this if we have seen a new executable
5459 edge; this helps us avoid an overflow infinity for conditionals
5460 which are not in a loop. */
5461 if (lhs_vr
->type
== VR_RANGE
&& vr_result
.type
== VR_RANGE
5462 && edges
<= old_edges
)
5464 if (!POINTER_TYPE_P (TREE_TYPE (lhs
)))
5466 int cmp_min
= compare_values (lhs_vr
->min
, vr_result
.min
);
5467 int cmp_max
= compare_values (lhs_vr
->max
, vr_result
.max
);
5469 /* If the new minimum is smaller or larger than the previous
5470 one, go all the way to -INF. In the first case, to avoid
5471 iterating millions of times to reach -INF, and in the
5472 other case to avoid infinite bouncing between different
5474 if (cmp_min
> 0 || cmp_min
< 0)
5476 /* If we will end up with a (-INF, +INF) range, set it
5478 if (vrp_val_is_max (vr_result
.max
))
5481 if (!needs_overflow_infinity (TREE_TYPE (vr_result
.min
))
5482 || !vrp_var_may_overflow (lhs
, phi
))
5483 vr_result
.min
= TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
));
5484 else if (supports_overflow_infinity (TREE_TYPE (vr_result
.min
)))
5486 negative_overflow_infinity (TREE_TYPE (vr_result
.min
));
5491 /* Similarly, if the new maximum is smaller or larger than
5492 the previous one, go all the way to +INF. */
5493 if (cmp_max
< 0 || cmp_max
> 0)
5495 /* If we will end up with a (-INF, +INF) range, set it
5497 if (vrp_val_is_min (vr_result
.min
))
5500 if (!needs_overflow_infinity (TREE_TYPE (vr_result
.max
))
5501 || !vrp_var_may_overflow (lhs
, phi
))
5502 vr_result
.max
= TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
));
5503 else if (supports_overflow_infinity (TREE_TYPE (vr_result
.max
)))
5505 positive_overflow_infinity (TREE_TYPE (vr_result
.max
));
5512 /* If the new range is different than the previous value, keep
5514 if (update_value_range (lhs
, &vr_result
))
5515 return SSA_PROP_INTERESTING
;
5517 /* Nothing changed, don't add outgoing edges. */
5518 return SSA_PROP_NOT_INTERESTING
;
5520 /* No match found. Set the LHS to VARYING. */
5522 set_value_range_to_varying (lhs_vr
);
5523 return SSA_PROP_VARYING
;
5526 /* Simplify a division or modulo operator to a right shift or
5527 bitwise and if the first operand is unsigned or is greater
5528 than zero and the second operand is an exact power of two. */
5531 simplify_div_or_mod_using_ranges (tree stmt
, tree rhs
, enum tree_code rhs_code
)
5534 tree op
= TREE_OPERAND (rhs
, 0);
5535 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
5537 if (TYPE_UNSIGNED (TREE_TYPE (op
)))
5539 val
= integer_one_node
;
5545 val
= compare_range_with_value (GT_EXPR
, vr
, integer_zero_node
, &sop
);
5549 && integer_onep (val
)
5550 && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC
))
5554 if (!EXPR_HAS_LOCATION (stmt
))
5555 locus
= input_location
;
5557 locus
= EXPR_LOCATION (stmt
);
5558 warning (OPT_Wstrict_overflow
,
5559 ("%Hassuming signed overflow does not occur when "
5560 "simplifying / or %% to >> or &"),
5565 if (val
&& integer_onep (val
))
5568 tree op0
= TREE_OPERAND (rhs
, 0);
5569 tree op1
= TREE_OPERAND (rhs
, 1);
5571 if (rhs_code
== TRUNC_DIV_EXPR
)
5573 t
= build_int_cst (NULL_TREE
, tree_log2 (op1
));
5574 t
= build2 (RSHIFT_EXPR
, TREE_TYPE (op0
), op0
, t
);
5578 t
= build_int_cst (TREE_TYPE (op1
), 1);
5579 t
= int_const_binop (MINUS_EXPR
, op1
, t
, 0);
5580 t
= fold_convert (TREE_TYPE (op0
), t
);
5581 t
= build2 (BIT_AND_EXPR
, TREE_TYPE (op0
), op0
, t
);
5584 GIMPLE_STMT_OPERAND (stmt
, 1) = t
;
5589 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
5590 ABS_EXPR. If the operand is <= 0, then simplify the
5591 ABS_EXPR into a NEGATE_EXPR. */
5594 simplify_abs_using_ranges (tree stmt
, tree rhs
)
5597 tree op
= TREE_OPERAND (rhs
, 0);
5598 tree type
= TREE_TYPE (op
);
5599 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
5601 if (TYPE_UNSIGNED (type
))
5603 val
= integer_zero_node
;
5609 val
= compare_range_with_value (LE_EXPR
, vr
, integer_zero_node
, &sop
);
5613 val
= compare_range_with_value (GE_EXPR
, vr
, integer_zero_node
,
5618 if (integer_zerop (val
))
5619 val
= integer_one_node
;
5620 else if (integer_onep (val
))
5621 val
= integer_zero_node
;
5626 && (integer_onep (val
) || integer_zerop (val
)))
5630 if (sop
&& issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC
))
5634 if (!EXPR_HAS_LOCATION (stmt
))
5635 locus
= input_location
;
5637 locus
= EXPR_LOCATION (stmt
);
5638 warning (OPT_Wstrict_overflow
,
5639 ("%Hassuming signed overflow does not occur when "
5640 "simplifying abs (X) to X or -X"),
5644 if (integer_onep (val
))
5645 t
= build1 (NEGATE_EXPR
, TREE_TYPE (op
), op
);
5649 GIMPLE_STMT_OPERAND (stmt
, 1) = t
;
5655 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
5656 a known value range VR.
5658 If there is one and only one value which will satisfy the
5659 conditional, then return that value. Else return NULL. */
5662 test_for_singularity (enum tree_code cond_code
, tree op0
,
5663 tree op1
, value_range_t
*vr
)
5668 /* Extract minimum/maximum values which satisfy the
5669 the conditional as it was written. */
5670 if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
5672 /* This should not be negative infinity; there is no overflow
5674 min
= TYPE_MIN_VALUE (TREE_TYPE (op0
));
5677 if (cond_code
== LT_EXPR
&& !is_overflow_infinity (max
))
5679 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
5680 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (op0
), max
, one
);
5682 TREE_NO_WARNING (max
) = 1;
5685 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
5687 /* This should not be positive infinity; there is no overflow
5689 max
= TYPE_MAX_VALUE (TREE_TYPE (op0
));
5692 if (cond_code
== GT_EXPR
&& !is_overflow_infinity (min
))
5694 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
5695 min
= fold_build2 (PLUS_EXPR
, TREE_TYPE (op0
), min
, one
);
5697 TREE_NO_WARNING (min
) = 1;
5701 /* Now refine the minimum and maximum values using any
5702 value range information we have for op0. */
5705 if (compare_values (vr
->min
, min
) == -1)
5709 if (compare_values (vr
->max
, max
) == 1)
5714 /* If the new min/max values have converged to a single value,
5715 then there is only one value which can satisfy the condition,
5716 return that value. */
5717 if (operand_equal_p (min
, max
, 0) && is_gimple_min_invariant (min
))
5723 /* Simplify a conditional using a relational operator to an equality
5724 test if the range information indicates only one value can satisfy
5725 the original conditional. */
5728 simplify_cond_using_ranges (tree stmt
)
5730 tree cond
= COND_EXPR_COND (stmt
);
5731 tree op0
= TREE_OPERAND (cond
, 0);
5732 tree op1
= TREE_OPERAND (cond
, 1);
5733 enum tree_code cond_code
= TREE_CODE (cond
);
5735 if (cond_code
!= NE_EXPR
5736 && cond_code
!= EQ_EXPR
5737 && TREE_CODE (op0
) == SSA_NAME
5738 && INTEGRAL_TYPE_P (TREE_TYPE (op0
))
5739 && is_gimple_min_invariant (op1
))
5741 value_range_t
*vr
= get_value_range (op0
);
5743 /* If we have range information for OP0, then we might be
5744 able to simplify this conditional. */
5745 if (vr
->type
== VR_RANGE
)
5747 tree
new = test_for_singularity (cond_code
, op0
, op1
, vr
);
5753 fprintf (dump_file
, "Simplified relational ");
5754 print_generic_expr (dump_file
, cond
, 0);
5755 fprintf (dump_file
, " into ");
5758 COND_EXPR_COND (stmt
)
5759 = build2 (EQ_EXPR
, boolean_type_node
, op0
, new);
5764 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
5765 fprintf (dump_file
, "\n");
5771 /* Try again after inverting the condition. We only deal
5772 with integral types here, so no need to worry about
5773 issues with inverting FP comparisons. */
5774 cond_code
= invert_tree_comparison (cond_code
, false);
5775 new = test_for_singularity (cond_code
, op0
, op1
, vr
);
5781 fprintf (dump_file
, "Simplified relational ");
5782 print_generic_expr (dump_file
, cond
, 0);
5783 fprintf (dump_file
, " into ");
5786 COND_EXPR_COND (stmt
)
5787 = build2 (NE_EXPR
, boolean_type_node
, op0
, new);
5792 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
5793 fprintf (dump_file
, "\n");
5802 /* Simplify STMT using ranges if possible. */
5805 simplify_stmt_using_ranges (tree stmt
)
5807 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
5809 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
5810 enum tree_code rhs_code
= TREE_CODE (rhs
);
5812 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
5813 and BIT_AND_EXPR respectively if the first operand is greater
5814 than zero and the second operand is an exact power of two. */
5815 if ((rhs_code
== TRUNC_DIV_EXPR
|| rhs_code
== TRUNC_MOD_EXPR
)
5816 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0)))
5817 && integer_pow2p (TREE_OPERAND (rhs
, 1)))
5818 simplify_div_or_mod_using_ranges (stmt
, rhs
, rhs_code
);
5820 /* Transform ABS (X) into X or -X as appropriate. */
5821 if (rhs_code
== ABS_EXPR
5822 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == SSA_NAME
5823 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0))))
5824 simplify_abs_using_ranges (stmt
, rhs
);
5826 else if (TREE_CODE (stmt
) == COND_EXPR
5827 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt
)))
5829 simplify_cond_using_ranges (stmt
);
5833 /* Stack of dest,src equivalency pairs that need to be restored after
5834 each attempt to thread a block's incoming edge to an outgoing edge.
5836 A NULL entry is used to mark the end of pairs which need to be
5838 static VEC(tree
,heap
) *stack
;
5840 /* A trivial wrapper so that we can present the generic jump threading
5841 code with a simple API for simplifying statements. STMT is the
5842 statement we want to simplify, WITHIN_STMT provides the location
5843 for any overflow warnings. */
5846 simplify_stmt_for_jump_threading (tree stmt
, tree within_stmt
)
5848 /* We only use VRP information to simplify conditionals. This is
5849 overly conservative, but it's unclear if doing more would be
5850 worth the compile time cost. */
5851 if (TREE_CODE (stmt
) != COND_EXPR
)
5854 return vrp_evaluate_conditional (COND_EXPR_COND (stmt
), within_stmt
);
5857 /* Blocks which have more than one predecessor and more than
5858 one successor present jump threading opportunities. ie,
5859 when the block is reached from a specific predecessor, we
5860 may be able to determine which of the outgoing edges will
5861 be traversed. When this optimization applies, we are able
5862 to avoid conditionals at runtime and we may expose secondary
5863 optimization opportunities.
5865 This routine is effectively a driver for the generic jump
5866 threading code. It basically just presents the generic code
5867 with edges that may be suitable for jump threading.
5869 Unlike DOM, we do not iterate VRP if jump threading was successful.
5870 While iterating may expose new opportunities for VRP, it is expected
5871 those opportunities would be very limited and the compile time cost
5872 to expose those opportunities would be significant.
5874 As jump threading opportunities are discovered, they are registered
5875 for later realization. */
5878 identify_jump_threads (void)
5883 /* Ugh. When substituting values earlier in this pass we can
5884 wipe the dominance information. So rebuild the dominator
5885 information as we need it within the jump threading code. */
5886 calculate_dominance_info (CDI_DOMINATORS
);
5888 /* We do not allow VRP information to be used for jump threading
5889 across a back edge in the CFG. Otherwise it becomes too
5890 difficult to avoid eliminating loop exit tests. Of course
5891 EDGE_DFS_BACK is not accurate at this time so we have to
5893 mark_dfs_back_edges ();
5895 /* Allocate our unwinder stack to unwind any temporary equivalences
5896 that might be recorded. */
5897 stack
= VEC_alloc (tree
, heap
, 20);
5899 /* To avoid lots of silly node creation, we create a single
5900 conditional and just modify it in-place when attempting to
5902 dummy
= build2 (EQ_EXPR
, boolean_type_node
, NULL
, NULL
);
5903 dummy
= build3 (COND_EXPR
, void_type_node
, dummy
, NULL
, NULL
);
5905 /* Walk through all the blocks finding those which present a
5906 potential jump threading opportunity. We could set this up
5907 as a dominator walker and record data during the walk, but
5908 I doubt it's worth the effort for the classes of jump
5909 threading opportunities we are trying to identify at this
5910 point in compilation. */
5915 /* If the generic jump threading code does not find this block
5916 interesting, then there is nothing to do. */
5917 if (! potentially_threadable_block (bb
))
5920 /* We only care about blocks ending in a COND_EXPR. While there
5921 may be some value in handling SWITCH_EXPR here, I doubt it's
5922 terribly important. */
5923 last
= bsi_stmt (bsi_last (bb
));
5924 if (TREE_CODE (last
) != COND_EXPR
)
5927 /* We're basically looking for any kind of conditional with
5928 integral type arguments. */
5929 cond
= COND_EXPR_COND (last
);
5930 if ((TREE_CODE (cond
) == SSA_NAME
5931 && INTEGRAL_TYPE_P (TREE_TYPE (cond
)))
5932 || (COMPARISON_CLASS_P (cond
)
5933 && TREE_CODE (TREE_OPERAND (cond
, 0)) == SSA_NAME
5934 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond
, 0)))
5935 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == SSA_NAME
5936 || is_gimple_min_invariant (TREE_OPERAND (cond
, 1)))
5937 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond
, 1)))))
5942 /* We've got a block with multiple predecessors and multiple
5943 successors which also ends in a suitable conditional. For
5944 each predecessor, see if we can thread it to a specific
5946 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
5948 /* Do not thread across back edges or abnormal edges
5950 if (e
->flags
& (EDGE_DFS_BACK
| EDGE_COMPLEX
))
5953 thread_across_edge (dummy
, e
, true,
5955 simplify_stmt_for_jump_threading
);
5960 /* We do not actually update the CFG or SSA graphs at this point as
5961 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
5962 handle ASSERT_EXPRs gracefully. */
5965 /* We identified all the jump threading opportunities earlier, but could
5966 not transform the CFG at that time. This routine transforms the
5967 CFG and arranges for the dominator tree to be rebuilt if necessary.
5969 Note the SSA graph update will occur during the normal TODO
5970 processing by the pass manager. */
5972 finalize_jump_threads (void)
5974 thread_through_all_blocks (false);
5975 VEC_free (tree
, heap
, stack
);
5979 /* Traverse all the blocks folding conditionals with known ranges. */
5985 prop_value_t
*single_val_range
;
5986 bool do_value_subst_p
;
5990 fprintf (dump_file
, "\nValue ranges after VRP:\n\n");
5991 dump_all_value_ranges (dump_file
);
5992 fprintf (dump_file
, "\n");
5995 /* We may have ended with ranges that have exactly one value. Those
5996 values can be substituted as any other copy/const propagated
5997 value using substitute_and_fold. */
5998 single_val_range
= XCNEWVEC (prop_value_t
, num_ssa_names
);
6000 do_value_subst_p
= false;
6001 for (i
= 0; i
< num_ssa_names
; i
++)
6003 && vr_value
[i
]->type
== VR_RANGE
6004 && vr_value
[i
]->min
== vr_value
[i
]->max
)
6006 single_val_range
[i
].value
= vr_value
[i
]->min
;
6007 do_value_subst_p
= true;
6010 if (!do_value_subst_p
)
6012 /* We found no single-valued ranges, don't waste time trying to
6013 do single value substitution in substitute_and_fold. */
6014 free (single_val_range
);
6015 single_val_range
= NULL
;
6018 substitute_and_fold (single_val_range
, true);
6020 if (warn_array_bounds
)
6021 check_all_array_refs ();
6023 /* We must identify jump threading opportunities before we release
6024 the datastructures built by VRP. */
6025 identify_jump_threads ();
6027 /* Free allocated memory. */
6028 for (i
= 0; i
< num_ssa_names
; i
++)
6031 BITMAP_FREE (vr_value
[i
]->equiv
);
6035 free (single_val_range
);
6037 free (vr_phi_edge_counts
);
6039 /* So that we can distinguish between VRP data being available
6040 and not available. */
6042 vr_phi_edge_counts
= NULL
;
6046 /* Main entry point to VRP (Value Range Propagation). This pass is
6047 loosely based on J. R. C. Patterson, ``Accurate Static Branch
6048 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
6049 Programming Language Design and Implementation, pp. 67-78, 1995.
6050 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
6052 This is essentially an SSA-CCP pass modified to deal with ranges
6053 instead of constants.
6055 While propagating ranges, we may find that two or more SSA name
6056 have equivalent, though distinct ranges. For instance,
6059 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
6061 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
6065 In the code above, pointer p_5 has range [q_2, q_2], but from the
6066 code we can also determine that p_5 cannot be NULL and, if q_2 had
6067 a non-varying range, p_5's range should also be compatible with it.
6069 These equivalences are created by two expressions: ASSERT_EXPR and
6070 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
6071 result of another assertion, then we can use the fact that p_5 and
6072 p_4 are equivalent when evaluating p_5's range.
6074 Together with value ranges, we also propagate these equivalences
6075 between names so that we can take advantage of information from
6076 multiple ranges when doing final replacement. Note that this
6077 equivalency relation is transitive but not symmetric.
6079 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
6080 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
6081 in contexts where that assertion does not hold (e.g., in line 6).
6083 TODO, the main difference between this pass and Patterson's is that
6084 we do not propagate edge probabilities. We only compute whether
6085 edges can be taken or not. That is, instead of having a spectrum
6086 of jump probabilities between 0 and 1, we only deal with 0, 1 and
6087 DON'T KNOW. In the future, it may be worthwhile to propagate
6088 probabilities to aid branch prediction. */
6093 loop_optimizer_init (LOOPS_NORMAL
| LOOPS_HAVE_RECORDED_EXITS
);
6094 rewrite_into_loop_closed_ssa (NULL
, TODO_update_ssa
);
6097 insert_range_assertions ();
6100 ssa_propagate (vrp_visit_stmt
, vrp_visit_phi_node
);
6103 /* ASSERT_EXPRs must be removed before finalizing jump threads
6104 as finalizing jump threads calls the CFG cleanup code which
6105 does not properly handle ASSERT_EXPRs. */
6106 remove_range_assertions ();
6108 /* If we exposed any new variables, go ahead and put them into
6109 SSA form now, before we handle jump threading. This simplifies
6110 interactions between rewriting of _DECL nodes into SSA form
6111 and rewriting SSA_NAME nodes into SSA form after block
6112 duplication and CFG manipulation. */
6113 update_ssa (TODO_update_ssa
);
6115 finalize_jump_threads ();
6117 loop_optimizer_finalize ();
6125 return flag_tree_vrp
!= 0;
6128 struct tree_opt_pass pass_vrp
=
6131 gate_vrp
, /* gate */
6132 execute_vrp
, /* execute */
6135 0, /* static_pass_number */
6136 TV_TREE_VRP
, /* tv_id */
6137 PROP_ssa
| PROP_alias
, /* properties_required */
6138 0, /* properties_provided */
6139 0, /* properties_destroyed */
6140 0, /* todo_flags_start */
6145 | TODO_update_ssa
, /* todo_flags_finish */