1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005, 2006 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"
36 #include "tree-scalar-evolution.h"
37 #include "tree-ssa-propagate.h"
38 #include "tree-chrec.h"
40 /* Set of SSA names found during the dominator traversal of a
41 sub-graph in find_assert_locations. */
42 static sbitmap found_in_subgraph
;
44 /* Local functions. */
45 static int compare_values (tree val1
, tree val2
);
47 /* Location information for ASSERT_EXPRs. Each instance of this
48 structure describes an ASSERT_EXPR for an SSA name. Since a single
49 SSA name may have more than one assertion associated with it, these
50 locations are kept in a linked list attached to the corresponding
54 /* Basic block where the assertion would be inserted. */
57 /* Some assertions need to be inserted on an edge (e.g., assertions
58 generated by COND_EXPRs). In those cases, BB will be NULL. */
61 /* Pointer to the statement that generated this assertion. */
62 block_stmt_iterator si
;
64 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
65 enum tree_code comp_code
;
67 /* Value being compared against. */
70 /* Next node in the linked list. */
71 struct assert_locus_d
*next
;
74 typedef struct assert_locus_d
*assert_locus_t
;
76 /* If bit I is present, it means that SSA name N_i has a list of
77 assertions that should be inserted in the IL. */
78 static bitmap need_assert_for
;
80 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
81 holds a list of ASSERT_LOCUS_T nodes that describe where
82 ASSERT_EXPRs for SSA name N_I should be inserted. */
83 static assert_locus_t
*asserts_for
;
85 /* Set of blocks visited in find_assert_locations. Used to avoid
86 visiting the same block more than once. */
87 static sbitmap blocks_visited
;
89 /* Value range array. After propagation, VR_VALUE[I] holds the range
90 of values that SSA name N_I may take. */
91 static value_range_t
**vr_value
;
94 /* Return true if ARG is marked with the nonnull attribute in the
95 current function signature. */
98 nonnull_arg_p (tree arg
)
100 tree t
, attrs
, fntype
;
101 unsigned HOST_WIDE_INT arg_num
;
103 gcc_assert (TREE_CODE (arg
) == PARM_DECL
&& POINTER_TYPE_P (TREE_TYPE (arg
)));
105 /* The static chain decl is always non null. */
106 if (arg
== cfun
->static_chain_decl
)
109 fntype
= TREE_TYPE (current_function_decl
);
110 attrs
= lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype
));
112 /* If "nonnull" wasn't specified, we know nothing about the argument. */
113 if (attrs
== NULL_TREE
)
116 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
117 if (TREE_VALUE (attrs
) == NULL_TREE
)
120 /* Get the position number for ARG in the function signature. */
121 for (arg_num
= 1, t
= DECL_ARGUMENTS (current_function_decl
);
123 t
= TREE_CHAIN (t
), arg_num
++)
129 gcc_assert (t
== arg
);
131 /* Now see if ARG_NUM is mentioned in the nonnull list. */
132 for (t
= TREE_VALUE (attrs
); t
; t
= TREE_CHAIN (t
))
134 if (compare_tree_int (TREE_VALUE (t
), arg_num
) == 0)
142 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
145 set_value_range (value_range_t
*vr
, enum value_range_type t
, tree min
,
146 tree max
, bitmap equiv
)
148 #if defined ENABLE_CHECKING
149 /* Check the validity of the range. */
150 if (t
== VR_RANGE
|| t
== VR_ANTI_RANGE
)
154 gcc_assert (min
&& max
);
156 if (INTEGRAL_TYPE_P (TREE_TYPE (min
)) && t
== VR_ANTI_RANGE
)
157 gcc_assert (min
!= TYPE_MIN_VALUE (TREE_TYPE (min
))
158 || max
!= TYPE_MAX_VALUE (TREE_TYPE (max
)));
160 cmp
= compare_values (min
, max
);
161 gcc_assert (cmp
== 0 || cmp
== -1 || cmp
== -2);
164 if (t
== VR_UNDEFINED
|| t
== VR_VARYING
)
165 gcc_assert (min
== NULL_TREE
&& max
== NULL_TREE
);
167 if (t
== VR_UNDEFINED
|| t
== VR_VARYING
)
168 gcc_assert (equiv
== NULL
|| bitmap_empty_p (equiv
));
175 /* Since updating the equivalence set involves deep copying the
176 bitmaps, only do it if absolutely necessary. */
177 if (vr
->equiv
== NULL
)
178 vr
->equiv
= BITMAP_ALLOC (NULL
);
180 if (equiv
!= vr
->equiv
)
182 if (equiv
&& !bitmap_empty_p (equiv
))
183 bitmap_copy (vr
->equiv
, equiv
);
185 bitmap_clear (vr
->equiv
);
190 /* Copy value range FROM into value range TO. */
193 copy_value_range (value_range_t
*to
, value_range_t
*from
)
195 set_value_range (to
, from
->type
, from
->min
, from
->max
, from
->equiv
);
198 /* Set value range VR to a non-negative range of type TYPE. */
201 set_value_range_to_nonnegative (value_range_t
*vr
, tree type
)
203 tree zero
= build_int_cst (type
, 0);
204 set_value_range (vr
, VR_RANGE
, zero
, TYPE_MAX_VALUE (type
), vr
->equiv
);
207 /* Set value range VR to a non-NULL range of type TYPE. */
210 set_value_range_to_nonnull (value_range_t
*vr
, tree type
)
212 tree zero
= build_int_cst (type
, 0);
213 set_value_range (vr
, VR_ANTI_RANGE
, zero
, zero
, vr
->equiv
);
217 /* Set value range VR to a NULL range of type TYPE. */
220 set_value_range_to_null (value_range_t
*vr
, tree type
)
222 tree zero
= build_int_cst (type
, 0);
223 set_value_range (vr
, VR_RANGE
, zero
, zero
, vr
->equiv
);
227 /* Set value range VR to VR_VARYING. */
230 set_value_range_to_varying (value_range_t
*vr
)
232 vr
->type
= VR_VARYING
;
233 vr
->min
= vr
->max
= NULL_TREE
;
235 bitmap_clear (vr
->equiv
);
239 /* Set value range VR to VR_UNDEFINED. */
242 set_value_range_to_undefined (value_range_t
*vr
)
244 vr
->type
= VR_UNDEFINED
;
245 vr
->min
= vr
->max
= NULL_TREE
;
247 bitmap_clear (vr
->equiv
);
251 /* Return value range information for VAR.
253 If we have no values ranges recorded (ie, VRP is not running), then
254 return NULL. Otherwise create an empty range if none existed for VAR. */
256 static value_range_t
*
257 get_value_range (tree var
)
261 unsigned ver
= SSA_NAME_VERSION (var
);
263 /* If we have no recorded ranges, then return NULL. */
271 /* Create a default value range. */
272 vr_value
[ver
] = vr
= XCNEW (value_range_t
);
274 /* Allocate an equivalence set. */
275 vr
->equiv
= BITMAP_ALLOC (NULL
);
277 /* If VAR is a default definition, the variable can take any value
279 sym
= SSA_NAME_VAR (var
);
280 if (SSA_NAME_IS_DEFAULT_DEF (var
))
282 /* Try to use the "nonnull" attribute to create ~[0, 0]
283 anti-ranges for pointers. Note that this is only valid with
284 default definitions of PARM_DECLs. */
285 if (TREE_CODE (sym
) == PARM_DECL
286 && POINTER_TYPE_P (TREE_TYPE (sym
))
287 && nonnull_arg_p (sym
))
288 set_value_range_to_nonnull (vr
, TREE_TYPE (sym
));
290 set_value_range_to_varying (vr
);
296 /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */
299 vrp_operand_equal_p (tree val1
, tree val2
)
303 && operand_equal_p (val1
, val2
, 0)));
306 /* Return true, if the bitmaps B1 and B2 are equal. */
309 vrp_bitmap_equal_p (bitmap b1
, bitmap b2
)
313 && bitmap_equal_p (b1
, b2
)));
316 /* Update the value range and equivalence set for variable VAR to
317 NEW_VR. Return true if NEW_VR is different from VAR's previous
320 NOTE: This function assumes that NEW_VR is a temporary value range
321 object created for the sole purpose of updating VAR's range. The
322 storage used by the equivalence set from NEW_VR will be freed by
323 this function. Do not call update_value_range when NEW_VR
324 is the range object associated with another SSA name. */
327 update_value_range (tree var
, value_range_t
*new_vr
)
329 value_range_t
*old_vr
;
332 /* Update the value range, if necessary. */
333 old_vr
= get_value_range (var
);
334 is_new
= old_vr
->type
!= new_vr
->type
335 || !vrp_operand_equal_p (old_vr
->min
, new_vr
->min
)
336 || !vrp_operand_equal_p (old_vr
->max
, new_vr
->max
)
337 || !vrp_bitmap_equal_p (old_vr
->equiv
, new_vr
->equiv
);
340 set_value_range (old_vr
, new_vr
->type
, new_vr
->min
, new_vr
->max
,
343 BITMAP_FREE (new_vr
->equiv
);
344 new_vr
->equiv
= NULL
;
350 /* Add VAR and VAR's equivalence set to EQUIV. */
353 add_equivalence (bitmap equiv
, tree var
)
355 unsigned ver
= SSA_NAME_VERSION (var
);
356 value_range_t
*vr
= vr_value
[ver
];
358 bitmap_set_bit (equiv
, ver
);
360 bitmap_ior_into (equiv
, vr
->equiv
);
364 /* Return true if VR is ~[0, 0]. */
367 range_is_nonnull (value_range_t
*vr
)
369 return vr
->type
== VR_ANTI_RANGE
370 && integer_zerop (vr
->min
)
371 && integer_zerop (vr
->max
);
375 /* Return true if VR is [0, 0]. */
378 range_is_null (value_range_t
*vr
)
380 return vr
->type
== VR_RANGE
381 && integer_zerop (vr
->min
)
382 && integer_zerop (vr
->max
);
386 /* Return true if value range VR involves at least one symbol. */
389 symbolic_range_p (value_range_t
*vr
)
391 return (!is_gimple_min_invariant (vr
->min
)
392 || !is_gimple_min_invariant (vr
->max
));
395 /* Like tree_expr_nonnegative_p, but this function uses value ranges
399 vrp_expr_computes_nonnegative (tree expr
)
401 return tree_expr_nonnegative_p (expr
);
404 /* Like tree_expr_nonzero_p, but this function uses value ranges
408 vrp_expr_computes_nonzero (tree expr
)
410 if (tree_expr_nonzero_p (expr
))
413 /* If we have an expression of the form &X->a, then the expression
414 is nonnull if X is nonnull. */
415 if (TREE_CODE (expr
) == ADDR_EXPR
)
417 tree base
= get_base_address (TREE_OPERAND (expr
, 0));
419 if (base
!= NULL_TREE
420 && TREE_CODE (base
) == INDIRECT_REF
421 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
423 value_range_t
*vr
= get_value_range (TREE_OPERAND (base
, 0));
424 if (range_is_nonnull (vr
))
432 /* Returns true if EXPR is a valid value (as expected by compare_values) --
433 a gimple invariant, or SSA_NAME +- CST. */
436 valid_value_p (tree expr
)
438 if (TREE_CODE (expr
) == SSA_NAME
)
441 if (TREE_CODE (expr
) == PLUS_EXPR
442 || TREE_CODE (expr
) == MINUS_EXPR
)
443 return (TREE_CODE (TREE_OPERAND (expr
, 0)) == SSA_NAME
444 && TREE_CODE (TREE_OPERAND (expr
, 1)) == INTEGER_CST
);
446 return is_gimple_min_invariant (expr
);
452 -2 if those are incomparable. */
454 operand_less_p (tree val
, tree val2
)
457 /* LT is folded faster than GE and others. Inline the common case. */
458 if (TREE_CODE (val
) == INTEGER_CST
&& TREE_CODE (val2
) == INTEGER_CST
)
460 if (TYPE_UNSIGNED (TREE_TYPE (val
)))
461 return INT_CST_LT_UNSIGNED (val
, val2
);
463 return INT_CST_LT (val
, val2
);
466 tcmp
= fold_binary_to_constant (LT_EXPR
, boolean_type_node
, val
, val2
);
469 return !integer_zerop (tcmp
);
472 /* Compare two values VAL1 and VAL2. Return
474 -2 if VAL1 and VAL2 cannot be compared at compile-time,
477 +1 if VAL1 > VAL2, and
480 This is similar to tree_int_cst_compare but supports pointer values
481 and values that cannot be compared at compile time. */
484 compare_values (tree val1
, tree val2
)
489 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
491 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1
))
492 == POINTER_TYPE_P (TREE_TYPE (val2
)));
494 if ((TREE_CODE (val1
) == SSA_NAME
495 || TREE_CODE (val1
) == PLUS_EXPR
496 || TREE_CODE (val1
) == MINUS_EXPR
)
497 && (TREE_CODE (val2
) == SSA_NAME
498 || TREE_CODE (val2
) == PLUS_EXPR
499 || TREE_CODE (val2
) == MINUS_EXPR
))
502 enum tree_code code1
, code2
;
504 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
505 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
506 same name, return -2. */
507 if (TREE_CODE (val1
) == SSA_NAME
)
515 code1
= TREE_CODE (val1
);
516 n1
= TREE_OPERAND (val1
, 0);
517 c1
= TREE_OPERAND (val1
, 1);
518 if (tree_int_cst_sgn (c1
) == -1)
520 c1
= fold_unary_to_constant (NEGATE_EXPR
, TREE_TYPE (c1
), c1
);
523 code1
= code1
== MINUS_EXPR
? PLUS_EXPR
: MINUS_EXPR
;
527 if (TREE_CODE (val2
) == SSA_NAME
)
535 code2
= TREE_CODE (val2
);
536 n2
= TREE_OPERAND (val2
, 0);
537 c2
= TREE_OPERAND (val2
, 1);
538 if (tree_int_cst_sgn (c2
) == -1)
540 c2
= fold_unary_to_constant (NEGATE_EXPR
, TREE_TYPE (c2
), c2
);
543 code2
= code2
== MINUS_EXPR
? PLUS_EXPR
: MINUS_EXPR
;
547 /* Both values must use the same name. */
551 if (code1
== SSA_NAME
552 && code2
== SSA_NAME
)
556 /* If overflow is defined we cannot simplify more. */
557 if (TYPE_UNSIGNED (TREE_TYPE (val1
))
561 if (code1
== SSA_NAME
)
563 if (code2
== PLUS_EXPR
)
564 /* NAME < NAME + CST */
566 else if (code2
== MINUS_EXPR
)
567 /* NAME > NAME - CST */
570 else if (code1
== PLUS_EXPR
)
572 if (code2
== SSA_NAME
)
573 /* NAME + CST > NAME */
575 else if (code2
== PLUS_EXPR
)
576 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
577 return compare_values (c1
, c2
);
578 else if (code2
== MINUS_EXPR
)
579 /* NAME + CST1 > NAME - CST2 */
582 else if (code1
== MINUS_EXPR
)
584 if (code2
== SSA_NAME
)
585 /* NAME - CST < NAME */
587 else if (code2
== PLUS_EXPR
)
588 /* NAME - CST1 < NAME + CST2 */
590 else if (code2
== MINUS_EXPR
)
591 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
592 C1 and C2 are swapped in the call to compare_values. */
593 return compare_values (c2
, c1
);
599 /* We cannot compare non-constants. */
600 if (!is_gimple_min_invariant (val1
) || !is_gimple_min_invariant (val2
))
603 if (!POINTER_TYPE_P (TREE_TYPE (val1
)))
605 /* We cannot compare overflowed values. */
606 if (TREE_OVERFLOW (val1
) || TREE_OVERFLOW (val2
))
609 return tree_int_cst_compare (val1
, val2
);
615 /* First see if VAL1 and VAL2 are not the same. */
616 if (val1
== val2
|| operand_equal_p (val1
, val2
, 0))
619 /* If VAL1 is a lower address than VAL2, return -1. */
620 if (operand_less_p (val1
, val2
) == 1)
623 /* If VAL1 is a higher address than VAL2, return +1. */
624 if (operand_less_p (val2
, val1
) == 1)
627 /* If VAL1 is different than VAL2, return +2.
628 For integer constants we either have already returned -1 or 1
629 or they are equivalent. We still might succeed in proving
630 something about non-trivial operands. */
631 if (TREE_CODE (val1
) != INTEGER_CST
632 || TREE_CODE (val2
) != INTEGER_CST
)
634 t
= fold_binary_to_constant (NE_EXPR
, boolean_type_node
, val1
, val2
);
635 if (t
&& tree_expr_nonzero_p (t
))
644 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
645 0 if VAL is not inside VR,
646 -2 if we cannot tell either way.
648 FIXME, the current semantics of this functions are a bit quirky
649 when taken in the context of VRP. In here we do not care
650 about VR's type. If VR is the anti-range ~[3, 5] the call
651 value_inside_range (4, VR) will return 1.
653 This is counter-intuitive in a strict sense, but the callers
654 currently expect this. They are calling the function
655 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
656 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
659 This also applies to value_ranges_intersect_p and
660 range_includes_zero_p. The semantics of VR_RANGE and
661 VR_ANTI_RANGE should be encoded here, but that also means
662 adapting the users of these functions to the new semantics.
664 Benchmark compile/20001226-1.c compilation time after changing this
668 value_inside_range (tree val
, value_range_t
* vr
)
672 cmp1
= operand_less_p (val
, vr
->min
);
678 cmp2
= operand_less_p (vr
->max
, val
);
686 /* Return true if value ranges VR0 and VR1 have a non-empty
689 Benchmark compile/20001226-1.c compilation time after changing this
694 value_ranges_intersect_p (value_range_t
*vr0
, value_range_t
*vr1
)
696 /* The value ranges do not intersect if the maximum of the first range is
697 less than the minimum of the second range or vice versa.
698 When those relations are unknown, we can't do any better. */
699 if (operand_less_p (vr0
->max
, vr1
->min
) != 0)
701 if (operand_less_p (vr1
->max
, vr0
->min
) != 0)
707 /* Return true if VR includes the value zero, false otherwise. FIXME,
708 currently this will return false for an anti-range like ~[-4, 3].
709 This will be wrong when the semantics of value_inside_range are
710 modified (currently the users of this function expect these
714 range_includes_zero_p (value_range_t
*vr
)
718 gcc_assert (vr
->type
!= VR_UNDEFINED
719 && vr
->type
!= VR_VARYING
720 && !symbolic_range_p (vr
));
722 zero
= build_int_cst (TREE_TYPE (vr
->min
), 0);
723 return (value_inside_range (zero
, vr
) == 1);
726 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
727 false otherwise or if no value range information is available. */
730 ssa_name_nonnegative_p (tree t
)
732 value_range_t
*vr
= get_value_range (t
);
737 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
738 which would return a useful value should be encoded as a VR_RANGE. */
739 if (vr
->type
== VR_RANGE
)
741 int result
= compare_values (vr
->min
, integer_zero_node
);
743 return (result
== 0 || result
== 1);
748 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
749 false otherwise or if no value range information is available. */
752 ssa_name_nonzero_p (tree t
)
754 value_range_t
*vr
= get_value_range (t
);
759 /* A VR_RANGE which does not include zero is a nonzero value. */
760 if (vr
->type
== VR_RANGE
&& !symbolic_range_p (vr
))
761 return ! range_includes_zero_p (vr
);
763 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
764 if (vr
->type
== VR_ANTI_RANGE
&& !symbolic_range_p (vr
))
765 return range_includes_zero_p (vr
);
771 /* Extract value range information from an ASSERT_EXPR EXPR and store
775 extract_range_from_assert (value_range_t
*vr_p
, tree expr
)
777 tree var
, cond
, limit
, min
, max
, type
;
778 value_range_t
*var_vr
, *limit_vr
;
779 enum tree_code cond_code
;
781 var
= ASSERT_EXPR_VAR (expr
);
782 cond
= ASSERT_EXPR_COND (expr
);
784 gcc_assert (COMPARISON_CLASS_P (cond
));
786 /* Find VAR in the ASSERT_EXPR conditional. */
787 if (var
== TREE_OPERAND (cond
, 0))
789 /* If the predicate is of the form VAR COMP LIMIT, then we just
790 take LIMIT from the RHS and use the same comparison code. */
791 limit
= TREE_OPERAND (cond
, 1);
792 cond_code
= TREE_CODE (cond
);
796 /* If the predicate is of the form LIMIT COMP VAR, then we need
797 to flip around the comparison code to create the proper range
799 limit
= TREE_OPERAND (cond
, 0);
800 cond_code
= swap_tree_comparison (TREE_CODE (cond
));
803 type
= TREE_TYPE (limit
);
804 gcc_assert (limit
!= var
);
806 /* For pointer arithmetic, we only keep track of pointer equality
808 if (POINTER_TYPE_P (type
) && cond_code
!= NE_EXPR
&& cond_code
!= EQ_EXPR
)
810 set_value_range_to_varying (vr_p
);
814 /* If LIMIT is another SSA name and LIMIT has a range of its own,
815 try to use LIMIT's range to avoid creating symbolic ranges
817 limit_vr
= (TREE_CODE (limit
) == SSA_NAME
) ? get_value_range (limit
) : NULL
;
819 /* LIMIT's range is only interesting if it has any useful information. */
821 && (limit_vr
->type
== VR_UNDEFINED
822 || limit_vr
->type
== VR_VARYING
823 || symbolic_range_p (limit_vr
)))
826 /* Initially, the new range has the same set of equivalences of
827 VAR's range. This will be revised before returning the final
828 value. Since assertions may be chained via mutually exclusive
829 predicates, we will need to trim the set of equivalences before
831 gcc_assert (vr_p
->equiv
== NULL
);
832 vr_p
->equiv
= BITMAP_ALLOC (NULL
);
833 add_equivalence (vr_p
->equiv
, var
);
835 /* Extract a new range based on the asserted comparison for VAR and
836 LIMIT's value range. Notice that if LIMIT has an anti-range, we
837 will only use it for equality comparisons (EQ_EXPR). For any
838 other kind of assertion, we cannot derive a range from LIMIT's
839 anti-range that can be used to describe the new range. For
840 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
841 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
842 no single range for x_2 that could describe LE_EXPR, so we might
843 as well build the range [b_4, +INF] for it. */
844 if (cond_code
== EQ_EXPR
)
846 enum value_range_type range_type
;
850 range_type
= limit_vr
->type
;
856 range_type
= VR_RANGE
;
861 set_value_range (vr_p
, range_type
, min
, max
, vr_p
->equiv
);
863 /* When asserting the equality VAR == LIMIT and LIMIT is another
864 SSA name, the new range will also inherit the equivalence set
866 if (TREE_CODE (limit
) == SSA_NAME
)
867 add_equivalence (vr_p
->equiv
, limit
);
869 else if (cond_code
== NE_EXPR
)
871 /* As described above, when LIMIT's range is an anti-range and
872 this assertion is an inequality (NE_EXPR), then we cannot
873 derive anything from the anti-range. For instance, if
874 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
875 not imply that VAR's range is [0, 0]. So, in the case of
876 anti-ranges, we just assert the inequality using LIMIT and
879 If LIMIT_VR is a range, we can only use it to build a new
880 anti-range if LIMIT_VR is a single-valued range. For
881 instance, if LIMIT_VR is [0, 1], the predicate
882 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
883 Rather, it means that for value 0 VAR should be ~[0, 0]
884 and for value 1, VAR should be ~[1, 1]. We cannot
885 represent these ranges.
887 The only situation in which we can build a valid
888 anti-range is when LIMIT_VR is a single-valued range
889 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
890 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
892 && limit_vr
->type
== VR_RANGE
893 && compare_values (limit_vr
->min
, limit_vr
->max
) == 0)
900 /* In any other case, we cannot use LIMIT's range to build a
905 /* If MIN and MAX cover the whole range for their type, then
906 just use the original LIMIT. */
907 if (INTEGRAL_TYPE_P (type
)
908 && min
== TYPE_MIN_VALUE (type
)
909 && max
== TYPE_MAX_VALUE (type
))
912 set_value_range (vr_p
, VR_ANTI_RANGE
, min
, max
, vr_p
->equiv
);
914 else if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
916 min
= TYPE_MIN_VALUE (type
);
918 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
922 /* If LIMIT_VR is of the form [N1, N2], we need to build the
923 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
928 /* If the maximum value forces us to be out of bounds, simply punt.
929 It would be pointless to try and do anything more since this
930 all should be optimized away above us. */
931 if (cond_code
== LT_EXPR
&& compare_values (max
, min
) == 0)
932 set_value_range_to_varying (vr_p
);
935 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
936 if (cond_code
== LT_EXPR
)
938 tree one
= build_int_cst (type
, 1);
939 max
= fold_build2 (MINUS_EXPR
, type
, max
, one
);
942 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
945 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
947 max
= TYPE_MAX_VALUE (type
);
949 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
953 /* If LIMIT_VR is of the form [N1, N2], we need to build the
954 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
959 /* If the minimum value forces us to be out of bounds, simply punt.
960 It would be pointless to try and do anything more since this
961 all should be optimized away above us. */
962 if (cond_code
== GT_EXPR
&& compare_values (min
, max
) == 0)
963 set_value_range_to_varying (vr_p
);
966 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
967 if (cond_code
== GT_EXPR
)
969 tree one
= build_int_cst (type
, 1);
970 min
= fold_build2 (PLUS_EXPR
, type
, min
, one
);
973 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
979 /* If VAR already had a known range, it may happen that the new
980 range we have computed and VAR's range are not compatible. For
984 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
986 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
988 While the above comes from a faulty program, it will cause an ICE
989 later because p_8 and p_6 will have incompatible ranges and at
990 the same time will be considered equivalent. A similar situation
994 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
996 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
998 Again i_6 and i_7 will have incompatible ranges. It would be
999 pointless to try and do anything with i_7's range because
1000 anything dominated by 'if (i_5 < 5)' will be optimized away.
1001 Note, due to the wa in which simulation proceeds, the statement
1002 i_7 = ASSERT_EXPR <...> we would never be visited because the
1003 conditional 'if (i_5 < 5)' always evaluates to false. However,
1004 this extra check does not hurt and may protect against future
1005 changes to VRP that may get into a situation similar to the
1006 NULL pointer dereference example.
1008 Note that these compatibility tests are only needed when dealing
1009 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1010 are both anti-ranges, they will always be compatible, because two
1011 anti-ranges will always have a non-empty intersection. */
1013 var_vr
= get_value_range (var
);
1015 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1016 ranges or anti-ranges. */
1017 if (vr_p
->type
== VR_VARYING
1018 || vr_p
->type
== VR_UNDEFINED
1019 || var_vr
->type
== VR_VARYING
1020 || var_vr
->type
== VR_UNDEFINED
1021 || symbolic_range_p (vr_p
)
1022 || symbolic_range_p (var_vr
))
1025 if (var_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_RANGE
)
1027 /* If the two ranges have a non-empty intersection, we can
1028 refine the resulting range. Since the assert expression
1029 creates an equivalency and at the same time it asserts a
1030 predicate, we can take the intersection of the two ranges to
1031 get better precision. */
1032 if (value_ranges_intersect_p (var_vr
, vr_p
))
1034 /* Use the larger of the two minimums. */
1035 if (compare_values (vr_p
->min
, var_vr
->min
) == -1)
1040 /* Use the smaller of the two maximums. */
1041 if (compare_values (vr_p
->max
, var_vr
->max
) == 1)
1046 set_value_range (vr_p
, vr_p
->type
, min
, max
, vr_p
->equiv
);
1050 /* The two ranges do not intersect, set the new range to
1051 VARYING, because we will not be able to do anything
1052 meaningful with it. */
1053 set_value_range_to_varying (vr_p
);
1056 else if ((var_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_ANTI_RANGE
)
1057 || (var_vr
->type
== VR_ANTI_RANGE
&& vr_p
->type
== VR_RANGE
))
1059 /* A range and an anti-range will cancel each other only if
1060 their ends are the same. For instance, in the example above,
1061 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1062 so VR_P should be set to VR_VARYING. */
1063 if (compare_values (var_vr
->min
, vr_p
->min
) == 0
1064 && compare_values (var_vr
->max
, vr_p
->max
) == 0)
1065 set_value_range_to_varying (vr_p
);
1068 tree min
, max
, anti_min
, anti_max
, real_min
, real_max
;
1070 /* We want to compute the logical AND of the two ranges;
1071 there are three cases to consider.
1074 1. The VR_ANTI_RANGE range is completely within the
1075 VR_RANGE and the endpoints of the ranges are
1076 different. In that case the resulting range
1077 should be whichever range is more precise.
1078 Typically that will be the VR_RANGE.
1080 2. The VR_ANTI_RANGE is completely disjoint from
1081 the VR_RANGE. In this case the resulting range
1082 should be the VR_RANGE.
1084 3. There is some overlap between the VR_ANTI_RANGE
1087 3a. If the high limit of the VR_ANTI_RANGE resides
1088 within the VR_RANGE, then the result is a new
1089 VR_RANGE starting at the high limit of the
1090 the VR_ANTI_RANGE + 1 and extending to the
1091 high limit of the original VR_RANGE.
1093 3b. If the low limit of the VR_ANTI_RANGE resides
1094 within the VR_RANGE, then the result is a new
1095 VR_RANGE starting at the low limit of the original
1096 VR_RANGE and extending to the low limit of the
1097 VR_ANTI_RANGE - 1. */
1098 if (vr_p
->type
== VR_ANTI_RANGE
)
1100 anti_min
= vr_p
->min
;
1101 anti_max
= vr_p
->max
;
1102 real_min
= var_vr
->min
;
1103 real_max
= var_vr
->max
;
1107 anti_min
= var_vr
->min
;
1108 anti_max
= var_vr
->max
;
1109 real_min
= vr_p
->min
;
1110 real_max
= vr_p
->max
;
1114 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1115 not including any endpoints. */
1116 if (compare_values (anti_max
, real_max
) == -1
1117 && compare_values (anti_min
, real_min
) == 1)
1119 set_value_range (vr_p
, VR_RANGE
, real_min
,
1120 real_max
, vr_p
->equiv
);
1122 /* Case 2, VR_ANTI_RANGE completely disjoint from
1124 else if (compare_values (anti_min
, real_max
) == 1
1125 || compare_values (anti_max
, real_min
) == -1)
1127 set_value_range (vr_p
, VR_RANGE
, real_min
,
1128 real_max
, vr_p
->equiv
);
1130 /* Case 3a, the anti-range extends into the low
1131 part of the real range. Thus creating a new
1132 low for the real range. */
1133 else if ((compare_values (anti_max
, real_min
) == 1
1134 || compare_values (anti_max
, real_min
) == 0)
1135 && compare_values (anti_max
, real_max
) == -1)
1137 min
= fold_build2 (PLUS_EXPR
, TREE_TYPE (var_vr
->min
),
1139 build_int_cst (TREE_TYPE (var_vr
->min
), 1));
1141 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1143 /* Case 3b, the anti-range extends into the high
1144 part of the real range. Thus creating a new
1145 higher for the real range. */
1146 else if (compare_values (anti_min
, real_min
) == 1
1147 && (compare_values (anti_min
, real_max
) == -1
1148 || compare_values (anti_min
, real_max
) == 0))
1150 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (var_vr
->min
),
1152 build_int_cst (TREE_TYPE (var_vr
->min
), 1));
1154 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1161 /* Extract range information from SSA name VAR and store it in VR. If
1162 VAR has an interesting range, use it. Otherwise, create the
1163 range [VAR, VAR] and return it. This is useful in situations where
1164 we may have conditionals testing values of VARYING names. For
1171 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1175 extract_range_from_ssa_name (value_range_t
*vr
, tree var
)
1177 value_range_t
*var_vr
= get_value_range (var
);
1179 if (var_vr
->type
!= VR_UNDEFINED
&& var_vr
->type
!= VR_VARYING
)
1180 copy_value_range (vr
, var_vr
);
1182 set_value_range (vr
, VR_RANGE
, var
, var
, NULL
);
1184 add_equivalence (vr
->equiv
, var
);
1188 /* Wrapper around int_const_binop. If the operation overflows and we
1189 are not using wrapping arithmetic, then adjust the result to be
1190 -INF or +INF depending on CODE, VAL1 and VAL2. */
1193 vrp_int_const_binop (enum tree_code code
, tree val1
, tree val2
)
1197 res
= int_const_binop (code
, val1
, val2
, 0);
1199 /* If we are not using wrapping arithmetic, operate symbolically
1200 on -INF and +INF. */
1201 if (TYPE_UNSIGNED (TREE_TYPE (val1
))
1204 int checkz
= compare_values (res
, val1
);
1205 bool overflow
= false;
1207 /* Ensure that res = val1 [+*] val2 >= val1
1208 or that res = val1 - val2 <= val1. */
1209 if ((code
== PLUS_EXPR
1210 && !(checkz
== 1 || checkz
== 0))
1211 || (code
== MINUS_EXPR
1212 && !(checkz
== 0 || checkz
== -1)))
1216 /* Checking for multiplication overflow is done by dividing the
1217 output of the multiplication by the first input of the
1218 multiplication. If the result of that division operation is
1219 not equal to the second input of the multiplication, then the
1220 multiplication overflowed. */
1221 else if (code
== MULT_EXPR
&& !integer_zerop (val1
))
1223 tree tmp
= int_const_binop (TRUNC_DIV_EXPR
,
1226 int check
= compare_values (tmp
, val2
);
1234 res
= copy_node (res
);
1235 TREE_OVERFLOW (res
) = 1;
1239 else if (TREE_OVERFLOW (res
)
1240 && !TREE_OVERFLOW (val1
)
1241 && !TREE_OVERFLOW (val2
))
1243 /* If the operation overflowed but neither VAL1 nor VAL2 are
1244 overflown, return -INF or +INF depending on the operation
1245 and the combination of signs of the operands. */
1246 int sgn1
= tree_int_cst_sgn (val1
);
1247 int sgn2
= tree_int_cst_sgn (val2
);
1249 /* Notice that we only need to handle the restricted set of
1250 operations handled by extract_range_from_binary_expr.
1251 Among them, only multiplication, addition and subtraction
1252 can yield overflow without overflown operands because we
1253 are working with integral types only... except in the
1254 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1255 for division too. */
1257 /* For multiplication, the sign of the overflow is given
1258 by the comparison of the signs of the operands. */
1259 if ((code
== MULT_EXPR
&& sgn1
== sgn2
)
1260 /* For addition, the operands must be of the same sign
1261 to yield an overflow. Its sign is therefore that
1262 of one of the operands, for example the first. */
1263 || (code
== PLUS_EXPR
&& sgn1
> 0)
1264 /* For subtraction, the operands must be of different
1265 signs to yield an overflow. Its sign is therefore
1266 that of the first operand or the opposite of that
1267 of the second operand. A first operand of 0 counts
1268 as positive here, for the corner case 0 - (-INF),
1269 which overflows, but must yield +INF. */
1270 || (code
== MINUS_EXPR
&& sgn1
>= 0)
1271 /* For division, the only case is -INF / -1 = +INF. */
1272 || code
== TRUNC_DIV_EXPR
1273 || code
== FLOOR_DIV_EXPR
1274 || code
== CEIL_DIV_EXPR
1275 || code
== EXACT_DIV_EXPR
1276 || code
== ROUND_DIV_EXPR
)
1277 return TYPE_MAX_VALUE (TREE_TYPE (res
));
1279 return TYPE_MIN_VALUE (TREE_TYPE (res
));
1286 /* Extract range information from a binary expression EXPR based on
1287 the ranges of each of its operands and the expression code. */
1290 extract_range_from_binary_expr (value_range_t
*vr
, tree expr
)
1292 enum tree_code code
= TREE_CODE (expr
);
1293 enum value_range_type type
;
1294 tree op0
, op1
, min
, max
;
1296 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1297 value_range_t vr1
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1299 /* Not all binary expressions can be applied to ranges in a
1300 meaningful way. Handle only arithmetic operations. */
1301 if (code
!= PLUS_EXPR
1302 && code
!= MINUS_EXPR
1303 && code
!= MULT_EXPR
1304 && code
!= TRUNC_DIV_EXPR
1305 && code
!= FLOOR_DIV_EXPR
1306 && code
!= CEIL_DIV_EXPR
1307 && code
!= EXACT_DIV_EXPR
1308 && code
!= ROUND_DIV_EXPR
1311 && code
!= BIT_AND_EXPR
1312 && code
!= TRUTH_ANDIF_EXPR
1313 && code
!= TRUTH_ORIF_EXPR
1314 && code
!= TRUTH_AND_EXPR
1315 && code
!= TRUTH_OR_EXPR
)
1317 set_value_range_to_varying (vr
);
1321 /* Get value ranges for each operand. For constant operands, create
1322 a new value range with the operand to simplify processing. */
1323 op0
= TREE_OPERAND (expr
, 0);
1324 if (TREE_CODE (op0
) == SSA_NAME
)
1325 vr0
= *(get_value_range (op0
));
1326 else if (is_gimple_min_invariant (op0
))
1327 set_value_range (&vr0
, VR_RANGE
, op0
, op0
, NULL
);
1329 set_value_range_to_varying (&vr0
);
1331 op1
= TREE_OPERAND (expr
, 1);
1332 if (TREE_CODE (op1
) == SSA_NAME
)
1333 vr1
= *(get_value_range (op1
));
1334 else if (is_gimple_min_invariant (op1
))
1335 set_value_range (&vr1
, VR_RANGE
, op1
, op1
, NULL
);
1337 set_value_range_to_varying (&vr1
);
1339 /* If either range is UNDEFINED, so is the result. */
1340 if (vr0
.type
== VR_UNDEFINED
|| vr1
.type
== VR_UNDEFINED
)
1342 set_value_range_to_undefined (vr
);
1346 /* The type of the resulting value range defaults to VR0.TYPE. */
1349 /* Refuse to operate on VARYING ranges, ranges of different kinds
1350 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1351 because we may be able to derive a useful range even if one of
1352 the operands is VR_VARYING or symbolic range. TODO, we may be
1353 able to derive anti-ranges in some cases. */
1354 if (code
!= BIT_AND_EXPR
1355 && code
!= TRUTH_AND_EXPR
1356 && code
!= TRUTH_OR_EXPR
1357 && (vr0
.type
== VR_VARYING
1358 || vr1
.type
== VR_VARYING
1359 || vr0
.type
!= vr1
.type
1360 || symbolic_range_p (&vr0
)
1361 || symbolic_range_p (&vr1
)))
1363 set_value_range_to_varying (vr
);
1367 /* Now evaluate the expression to determine the new range. */
1368 if (POINTER_TYPE_P (TREE_TYPE (expr
))
1369 || POINTER_TYPE_P (TREE_TYPE (op0
))
1370 || POINTER_TYPE_P (TREE_TYPE (op1
)))
1372 /* For pointer types, we are really only interested in asserting
1373 whether the expression evaluates to non-NULL. FIXME, we used
1374 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1375 ivopts is generating expressions with pointer multiplication
1377 if (code
== PLUS_EXPR
)
1379 if (range_is_nonnull (&vr0
) || range_is_nonnull (&vr1
))
1380 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1381 else if (range_is_null (&vr0
) && range_is_null (&vr1
))
1382 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1384 set_value_range_to_varying (vr
);
1388 /* Subtracting from a pointer, may yield 0, so just drop the
1389 resulting range to varying. */
1390 set_value_range_to_varying (vr
);
1396 /* For integer ranges, apply the operation to each end of the
1397 range and see what we end up with. */
1398 if (code
== TRUTH_ANDIF_EXPR
1399 || code
== TRUTH_ORIF_EXPR
1400 || code
== TRUTH_AND_EXPR
1401 || code
== TRUTH_OR_EXPR
)
1403 /* If one of the operands is zero, we know that the whole
1404 expression evaluates zero. */
1405 if (code
== TRUTH_AND_EXPR
1406 && ((vr0
.type
== VR_RANGE
1407 && integer_zerop (vr0
.min
)
1408 && integer_zerop (vr0
.max
))
1409 || (vr1
.type
== VR_RANGE
1410 && integer_zerop (vr1
.min
)
1411 && integer_zerop (vr1
.max
))))
1414 min
= max
= build_int_cst (TREE_TYPE (expr
), 0);
1416 /* If one of the operands is one, we know that the whole
1417 expression evaluates one. */
1418 else if (code
== TRUTH_OR_EXPR
1419 && ((vr0
.type
== VR_RANGE
1420 && integer_onep (vr0
.min
)
1421 && integer_onep (vr0
.max
))
1422 || (vr1
.type
== VR_RANGE
1423 && integer_onep (vr1
.min
)
1424 && integer_onep (vr1
.max
))))
1427 min
= max
= build_int_cst (TREE_TYPE (expr
), 1);
1429 else if (vr0
.type
!= VR_VARYING
1430 && vr1
.type
!= VR_VARYING
1431 && vr0
.type
== vr1
.type
1432 && !symbolic_range_p (&vr0
)
1433 && !symbolic_range_p (&vr1
))
1435 /* Boolean expressions cannot be folded with int_const_binop. */
1436 min
= fold_binary (code
, TREE_TYPE (expr
), vr0
.min
, vr1
.min
);
1437 max
= fold_binary (code
, TREE_TYPE (expr
), vr0
.max
, vr1
.max
);
1441 set_value_range_to_varying (vr
);
1445 else if (code
== PLUS_EXPR
1447 || code
== MAX_EXPR
)
1449 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1450 VR_VARYING. It would take more effort to compute a precise
1451 range for such a case. For example, if we have op0 == 1 and
1452 op1 == -1 with their ranges both being ~[0,0], we would have
1453 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1454 Note that we are guaranteed to have vr0.type == vr1.type at
1456 if (code
== PLUS_EXPR
&& vr0
.type
== VR_ANTI_RANGE
)
1458 set_value_range_to_varying (vr
);
1462 /* For operations that make the resulting range directly
1463 proportional to the original ranges, apply the operation to
1464 the same end of each range. */
1465 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1466 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.max
);
1468 else if (code
== MULT_EXPR
1469 || code
== TRUNC_DIV_EXPR
1470 || code
== FLOOR_DIV_EXPR
1471 || code
== CEIL_DIV_EXPR
1472 || code
== EXACT_DIV_EXPR
1473 || code
== ROUND_DIV_EXPR
)
1478 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1479 drop to VR_VARYING. It would take more effort to compute a
1480 precise range for such a case. For example, if we have
1481 op0 == 65536 and op1 == 65536 with their ranges both being
1482 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1483 we cannot claim that the product is in ~[0,0]. Note that we
1484 are guaranteed to have vr0.type == vr1.type at this
1486 if (code
== MULT_EXPR
1487 && vr0
.type
== VR_ANTI_RANGE
1488 && (flag_wrapv
|| TYPE_UNSIGNED (TREE_TYPE (op0
))))
1490 set_value_range_to_varying (vr
);
1494 /* Multiplications and divisions are a bit tricky to handle,
1495 depending on the mix of signs we have in the two ranges, we
1496 need to operate on different values to get the minimum and
1497 maximum values for the new range. One approach is to figure
1498 out all the variations of range combinations and do the
1501 However, this involves several calls to compare_values and it
1502 is pretty convoluted. It's simpler to do the 4 operations
1503 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1504 MAX1) and then figure the smallest and largest values to form
1507 /* Divisions by zero result in a VARYING value. */
1508 if (code
!= MULT_EXPR
1509 && (vr0
.type
== VR_ANTI_RANGE
|| range_includes_zero_p (&vr1
)))
1511 set_value_range_to_varying (vr
);
1515 /* Compute the 4 cross operations. */
1516 val
[0] = vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1518 val
[1] = (vr1
.max
!= vr1
.min
)
1519 ? vrp_int_const_binop (code
, vr0
.min
, vr1
.max
)
1522 val
[2] = (vr0
.max
!= vr0
.min
)
1523 ? vrp_int_const_binop (code
, vr0
.max
, vr1
.min
)
1526 val
[3] = (vr0
.min
!= vr0
.max
&& vr1
.min
!= vr1
.max
)
1527 ? vrp_int_const_binop (code
, vr0
.max
, vr1
.max
)
1530 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1534 for (i
= 1; i
< 4; i
++)
1536 if (!is_gimple_min_invariant (min
) || TREE_OVERFLOW (min
)
1537 || !is_gimple_min_invariant (max
) || TREE_OVERFLOW (max
))
1542 if (!is_gimple_min_invariant (val
[i
]) || TREE_OVERFLOW (val
[i
]))
1544 /* If we found an overflowed value, set MIN and MAX
1545 to it so that we set the resulting range to
1551 if (compare_values (val
[i
], min
) == -1)
1554 if (compare_values (val
[i
], max
) == 1)
1559 else if (code
== MINUS_EXPR
)
1561 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1562 VR_VARYING. It would take more effort to compute a precise
1563 range for such a case. For example, if we have op0 == 1 and
1564 op1 == 1 with their ranges both being ~[0,0], we would have
1565 op0 - op1 == 0, so we cannot claim that the difference is in
1566 ~[0,0]. Note that we are guaranteed to have
1567 vr0.type == vr1.type at this point. */
1568 if (vr0
.type
== VR_ANTI_RANGE
)
1570 set_value_range_to_varying (vr
);
1574 /* For MINUS_EXPR, apply the operation to the opposite ends of
1576 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.max
);
1577 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.min
);
1579 else if (code
== BIT_AND_EXPR
)
1581 if (vr0
.type
== VR_RANGE
1582 && vr0
.min
== vr0
.max
1583 && tree_expr_nonnegative_p (vr0
.max
)
1584 && TREE_CODE (vr0
.max
) == INTEGER_CST
)
1586 min
= build_int_cst (TREE_TYPE (expr
), 0);
1589 else if (vr1
.type
== VR_RANGE
1590 && vr1
.min
== vr1
.max
1591 && tree_expr_nonnegative_p (vr1
.max
)
1592 && TREE_CODE (vr1
.max
) == INTEGER_CST
)
1595 min
= build_int_cst (TREE_TYPE (expr
), 0);
1600 set_value_range_to_varying (vr
);
1607 /* If either MIN or MAX overflowed, then set the resulting range to
1609 if (!is_gimple_min_invariant (min
) || TREE_OVERFLOW (min
)
1610 || !is_gimple_min_invariant (max
) || TREE_OVERFLOW (max
))
1612 set_value_range_to_varying (vr
);
1616 cmp
= compare_values (min
, max
);
1617 if (cmp
== -2 || cmp
== 1)
1619 /* If the new range has its limits swapped around (MIN > MAX),
1620 then the operation caused one of them to wrap around, mark
1621 the new range VARYING. */
1622 set_value_range_to_varying (vr
);
1625 set_value_range (vr
, type
, min
, max
, NULL
);
1629 /* Extract range information from a unary expression EXPR based on
1630 the range of its operand and the expression code. */
1633 extract_range_from_unary_expr (value_range_t
*vr
, tree expr
)
1635 enum tree_code code
= TREE_CODE (expr
);
1638 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1640 /* Refuse to operate on certain unary expressions for which we
1641 cannot easily determine a resulting range. */
1642 if (code
== FIX_TRUNC_EXPR
1643 || code
== FLOAT_EXPR
1644 || code
== BIT_NOT_EXPR
1645 || code
== NON_LVALUE_EXPR
1646 || code
== CONJ_EXPR
)
1648 set_value_range_to_varying (vr
);
1652 /* Get value ranges for the operand. For constant operands, create
1653 a new value range with the operand to simplify processing. */
1654 op0
= TREE_OPERAND (expr
, 0);
1655 if (TREE_CODE (op0
) == SSA_NAME
)
1656 vr0
= *(get_value_range (op0
));
1657 else if (is_gimple_min_invariant (op0
))
1658 set_value_range (&vr0
, VR_RANGE
, op0
, op0
, NULL
);
1660 set_value_range_to_varying (&vr0
);
1662 /* If VR0 is UNDEFINED, so is the result. */
1663 if (vr0
.type
== VR_UNDEFINED
)
1665 set_value_range_to_undefined (vr
);
1669 /* Refuse to operate on symbolic ranges, or if neither operand is
1670 a pointer or integral type. */
1671 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
1672 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
1673 || (vr0
.type
!= VR_VARYING
1674 && symbolic_range_p (&vr0
)))
1676 set_value_range_to_varying (vr
);
1680 /* If the expression involves pointers, we are only interested in
1681 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1682 if (POINTER_TYPE_P (TREE_TYPE (expr
)) || POINTER_TYPE_P (TREE_TYPE (op0
)))
1684 if (range_is_nonnull (&vr0
) || tree_expr_nonzero_p (expr
))
1685 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1686 else if (range_is_null (&vr0
))
1687 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1689 set_value_range_to_varying (vr
);
1694 /* Handle unary expressions on integer ranges. */
1695 if (code
== NOP_EXPR
|| code
== CONVERT_EXPR
)
1697 tree inner_type
= TREE_TYPE (op0
);
1698 tree outer_type
= TREE_TYPE (expr
);
1700 /* If VR0 represents a simple range, then try to convert
1701 the min and max values for the range to the same type
1702 as OUTER_TYPE. If the results compare equal to VR0's
1703 min and max values and the new min is still less than
1704 or equal to the new max, then we can safely use the newly
1705 computed range for EXPR. This allows us to compute
1706 accurate ranges through many casts. */
1707 if (vr0
.type
== VR_RANGE
1708 || (vr0
.type
== VR_VARYING
1709 && TYPE_PRECISION (outer_type
) > TYPE_PRECISION (inner_type
)))
1711 tree new_min
, new_max
, orig_min
, orig_max
;
1713 /* Convert the input operand min/max to OUTER_TYPE. If
1714 the input has no range information, then use the min/max
1715 for the input's type. */
1716 if (vr0
.type
== VR_RANGE
)
1723 orig_min
= TYPE_MIN_VALUE (inner_type
);
1724 orig_max
= TYPE_MAX_VALUE (inner_type
);
1727 new_min
= fold_convert (outer_type
, orig_min
);
1728 new_max
= fold_convert (outer_type
, orig_max
);
1730 /* Verify the new min/max values are gimple values and
1731 that they compare equal to the original input's
1733 if (is_gimple_val (new_min
)
1734 && is_gimple_val (new_max
)
1735 && tree_int_cst_equal (new_min
, orig_min
)
1736 && tree_int_cst_equal (new_max
, orig_max
)
1737 && compare_values (new_min
, new_max
) <= 0
1738 && compare_values (new_min
, new_max
) >= -1)
1740 set_value_range (vr
, VR_RANGE
, new_min
, new_max
, vr
->equiv
);
1745 /* When converting types of different sizes, set the result to
1746 VARYING. Things like sign extensions and precision loss may
1747 change the range. For instance, if x_3 is of type 'long long
1748 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1749 is impossible to know at compile time whether y_5 will be
1751 if (TYPE_SIZE (inner_type
) != TYPE_SIZE (outer_type
)
1752 || TYPE_PRECISION (inner_type
) != TYPE_PRECISION (outer_type
))
1754 set_value_range_to_varying (vr
);
1759 /* Conversion of a VR_VARYING value to a wider type can result
1760 in a usable range. So wait until after we've handled conversions
1761 before dropping the result to VR_VARYING if we had a source
1762 operand that is VR_VARYING. */
1763 if (vr0
.type
== VR_VARYING
)
1765 set_value_range_to_varying (vr
);
1769 /* Apply the operation to each end of the range and see what we end
1771 if (code
== NEGATE_EXPR
1772 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
1774 /* NEGATE_EXPR flips the range around. We need to treat
1775 TYPE_MIN_VALUE specially dependent on wrapping, range type
1776 and if it was used as minimum or maximum value:
1777 -~[MIN, MIN] == ~[MIN, MIN]
1778 -[MIN, 0] == [0, MAX] for -fno-wrapv
1779 -[MIN, 0] == [0, MIN] for -fwrapv (will be set to varying later) */
1780 min
= vr0
.max
== TYPE_MIN_VALUE (TREE_TYPE (expr
))
1781 ? TYPE_MIN_VALUE (TREE_TYPE (expr
))
1782 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1784 max
= vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
))
1785 ? (vr0
.type
== VR_ANTI_RANGE
|| flag_wrapv
1786 ? TYPE_MIN_VALUE (TREE_TYPE (expr
))
1787 : TYPE_MAX_VALUE (TREE_TYPE (expr
)))
1788 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1791 else if (code
== NEGATE_EXPR
1792 && TYPE_UNSIGNED (TREE_TYPE (expr
)))
1794 if (!range_includes_zero_p (&vr0
))
1796 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1797 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1801 if (range_is_null (&vr0
))
1802 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1804 set_value_range_to_varying (vr
);
1808 else if (code
== ABS_EXPR
1809 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
1811 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1814 && ((vr0
.type
== VR_RANGE
1815 && vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
)))
1816 || (vr0
.type
== VR_ANTI_RANGE
1817 && vr0
.min
!= TYPE_MIN_VALUE (TREE_TYPE (expr
))
1818 && !range_includes_zero_p (&vr0
))))
1820 set_value_range_to_varying (vr
);
1824 /* ABS_EXPR may flip the range around, if the original range
1825 included negative values. */
1826 min
= (vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
)))
1827 ? TYPE_MAX_VALUE (TREE_TYPE (expr
))
1828 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1830 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1832 cmp
= compare_values (min
, max
);
1834 /* If a VR_ANTI_RANGEs contains zero, then we have
1835 ~[-INF, min(MIN, MAX)]. */
1836 if (vr0
.type
== VR_ANTI_RANGE
)
1838 if (range_includes_zero_p (&vr0
))
1840 tree type_min_value
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
1842 /* Take the lower of the two values. */
1846 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1847 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1848 flag_wrapv is set and the original anti-range doesn't include
1849 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1850 min
= (flag_wrapv
&& vr0
.min
!= type_min_value
1851 ? int_const_binop (PLUS_EXPR
,
1853 integer_one_node
, 0)
1858 /* All else has failed, so create the range [0, INF], even for
1859 flag_wrapv since TYPE_MIN_VALUE is in the original
1861 vr0
.type
= VR_RANGE
;
1862 min
= build_int_cst (TREE_TYPE (expr
), 0);
1863 max
= TYPE_MAX_VALUE (TREE_TYPE (expr
));
1867 /* If the range contains zero then we know that the minimum value in the
1868 range will be zero. */
1869 else if (range_includes_zero_p (&vr0
))
1873 min
= build_int_cst (TREE_TYPE (expr
), 0);
1877 /* If the range was reversed, swap MIN and MAX. */
1888 /* Otherwise, operate on each end of the range. */
1889 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1890 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1893 cmp
= compare_values (min
, max
);
1894 if (cmp
== -2 || cmp
== 1)
1896 /* If the new range has its limits swapped around (MIN > MAX),
1897 then the operation caused one of them to wrap around, mark
1898 the new range VARYING. */
1899 set_value_range_to_varying (vr
);
1902 set_value_range (vr
, vr0
.type
, min
, max
, NULL
);
1906 /* Extract range information from a comparison expression EXPR based
1907 on the range of its operand and the expression code. */
1910 extract_range_from_comparison (value_range_t
*vr
, tree expr
)
1912 tree val
= vrp_evaluate_conditional (expr
, false);
1915 /* Since this expression was found on the RHS of an assignment,
1916 its type may be different from _Bool. Convert VAL to EXPR's
1918 val
= fold_convert (TREE_TYPE (expr
), val
);
1919 set_value_range (vr
, VR_RANGE
, val
, val
, vr
->equiv
);
1922 set_value_range_to_varying (vr
);
1926 /* Try to compute a useful range out of expression EXPR and store it
1930 extract_range_from_expr (value_range_t
*vr
, tree expr
)
1932 enum tree_code code
= TREE_CODE (expr
);
1934 if (code
== ASSERT_EXPR
)
1935 extract_range_from_assert (vr
, expr
);
1936 else if (code
== SSA_NAME
)
1937 extract_range_from_ssa_name (vr
, expr
);
1938 else if (TREE_CODE_CLASS (code
) == tcc_binary
1939 || code
== TRUTH_ANDIF_EXPR
1940 || code
== TRUTH_ORIF_EXPR
1941 || code
== TRUTH_AND_EXPR
1942 || code
== TRUTH_OR_EXPR
1943 || code
== TRUTH_XOR_EXPR
)
1944 extract_range_from_binary_expr (vr
, expr
);
1945 else if (TREE_CODE_CLASS (code
) == tcc_unary
)
1946 extract_range_from_unary_expr (vr
, expr
);
1947 else if (TREE_CODE_CLASS (code
) == tcc_comparison
)
1948 extract_range_from_comparison (vr
, expr
);
1949 else if (is_gimple_min_invariant (expr
))
1950 set_value_range (vr
, VR_RANGE
, expr
, expr
, NULL
);
1952 set_value_range_to_varying (vr
);
1954 /* If we got a varying range from the tests above, try a final
1955 time to derive a nonnegative or nonzero range. This time
1956 relying primarily on generic routines in fold in conjunction
1958 if (vr
->type
== VR_VARYING
)
1960 if (INTEGRAL_TYPE_P (TREE_TYPE (expr
))
1961 && vrp_expr_computes_nonnegative (expr
))
1962 set_value_range_to_nonnegative (vr
, TREE_TYPE (expr
));
1963 else if (vrp_expr_computes_nonzero (expr
))
1964 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1968 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1969 would be profitable to adjust VR using scalar evolution information
1970 for VAR. If so, update VR with the new limits. */
1973 adjust_range_with_scev (value_range_t
*vr
, struct loop
*loop
, tree stmt
,
1976 tree init
, step
, chrec
, tmin
, tmax
, min
, max
, type
;
1977 enum ev_direction dir
;
1979 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1980 better opportunities than a regular range, but I'm not sure. */
1981 if (vr
->type
== VR_ANTI_RANGE
)
1984 chrec
= instantiate_parameters (loop
, analyze_scalar_evolution (loop
, var
));
1985 if (TREE_CODE (chrec
) != POLYNOMIAL_CHREC
)
1988 init
= initial_condition_in_loop_num (chrec
, loop
->num
);
1989 step
= evolution_part_in_loop_num (chrec
, loop
->num
);
1991 /* If STEP is symbolic, we can't know whether INIT will be the
1992 minimum or maximum value in the range. Also, unless INIT is
1993 a simple expression, compare_values and possibly other functions
1994 in tree-vrp won't be able to handle it. */
1995 if (step
== NULL_TREE
1996 || !is_gimple_min_invariant (step
)
1997 || !valid_value_p (init
))
2000 dir
= scev_direction (chrec
);
2001 if (/* Do not adjust ranges if we do not know whether the iv increases
2002 or decreases, ... */
2003 dir
== EV_DIR_UNKNOWN
2004 /* ... or if it may wrap. */
2005 || scev_probably_wraps_p (init
, step
, stmt
, get_chrec_loop (chrec
),
2009 type
= TREE_TYPE (var
);
2010 if (POINTER_TYPE_P (type
) || !TYPE_MIN_VALUE (type
))
2011 tmin
= lower_bound_in_type (type
, type
);
2013 tmin
= TYPE_MIN_VALUE (type
);
2014 if (POINTER_TYPE_P (type
) || !TYPE_MAX_VALUE (type
))
2015 tmax
= upper_bound_in_type (type
, type
);
2017 tmax
= TYPE_MAX_VALUE (type
);
2019 if (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
)
2024 /* For VARYING or UNDEFINED ranges, just about anything we get
2025 from scalar evolutions should be better. */
2027 if (dir
== EV_DIR_DECREASES
)
2032 /* If we would create an invalid range, then just assume we
2033 know absolutely nothing. This may be over-conservative,
2034 but it's clearly safe, and should happen only in unreachable
2035 parts of code, or for invalid programs. */
2036 if (compare_values (min
, max
) == 1)
2039 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
2041 else if (vr
->type
== VR_RANGE
)
2046 if (dir
== EV_DIR_DECREASES
)
2048 /* INIT is the maximum value. If INIT is lower than VR->MAX
2049 but no smaller than VR->MIN, set VR->MAX to INIT. */
2050 if (compare_values (init
, max
) == -1)
2054 /* If we just created an invalid range with the minimum
2055 greater than the maximum, we fail conservatively.
2056 This should happen only in unreachable
2057 parts of code, or for invalid programs. */
2058 if (compare_values (min
, max
) == 1)
2064 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2065 if (compare_values (init
, min
) == 1)
2069 /* Again, avoid creating invalid range by failing. */
2070 if (compare_values (min
, max
) == 1)
2075 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
2080 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2082 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2083 all the values in the ranges.
2085 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2087 - Return NULL_TREE if it is not always possible to determine the
2088 value of the comparison. */
2092 compare_ranges (enum tree_code comp
, value_range_t
*vr0
, value_range_t
*vr1
)
2094 /* VARYING or UNDEFINED ranges cannot be compared. */
2095 if (vr0
->type
== VR_VARYING
2096 || vr0
->type
== VR_UNDEFINED
2097 || vr1
->type
== VR_VARYING
2098 || vr1
->type
== VR_UNDEFINED
)
2101 /* Anti-ranges need to be handled separately. */
2102 if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
2104 /* If both are anti-ranges, then we cannot compute any
2106 if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
2109 /* These comparisons are never statically computable. */
2116 /* Equality can be computed only between a range and an
2117 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2118 if (vr0
->type
== VR_RANGE
)
2120 /* To simplify processing, make VR0 the anti-range. */
2121 value_range_t
*tmp
= vr0
;
2126 gcc_assert (comp
== NE_EXPR
|| comp
== EQ_EXPR
);
2128 if (compare_values (vr0
->min
, vr1
->min
) == 0
2129 && compare_values (vr0
->max
, vr1
->max
) == 0)
2130 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
2135 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2136 operands around and change the comparison code. */
2137 if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
2140 comp
= (comp
== GT_EXPR
) ? LT_EXPR
: LE_EXPR
;
2146 if (comp
== EQ_EXPR
)
2148 /* Equality may only be computed if both ranges represent
2149 exactly one value. */
2150 if (compare_values (vr0
->min
, vr0
->max
) == 0
2151 && compare_values (vr1
->min
, vr1
->max
) == 0)
2153 int cmp_min
= compare_values (vr0
->min
, vr1
->min
);
2154 int cmp_max
= compare_values (vr0
->max
, vr1
->max
);
2155 if (cmp_min
== 0 && cmp_max
== 0)
2156 return boolean_true_node
;
2157 else if (cmp_min
!= -2 && cmp_max
!= -2)
2158 return boolean_false_node
;
2160 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2161 else if (compare_values (vr0
->min
, vr1
->max
) == 1
2162 || compare_values (vr1
->min
, vr0
->max
) == 1)
2163 return boolean_false_node
;
2167 else if (comp
== NE_EXPR
)
2171 /* If VR0 is completely to the left or completely to the right
2172 of VR1, they are always different. Notice that we need to
2173 make sure that both comparisons yield similar results to
2174 avoid comparing values that cannot be compared at
2176 cmp1
= compare_values (vr0
->max
, vr1
->min
);
2177 cmp2
= compare_values (vr0
->min
, vr1
->max
);
2178 if ((cmp1
== -1 && cmp2
== -1) || (cmp1
== 1 && cmp2
== 1))
2179 return boolean_true_node
;
2181 /* If VR0 and VR1 represent a single value and are identical,
2183 else if (compare_values (vr0
->min
, vr0
->max
) == 0
2184 && compare_values (vr1
->min
, vr1
->max
) == 0
2185 && compare_values (vr0
->min
, vr1
->min
) == 0
2186 && compare_values (vr0
->max
, vr1
->max
) == 0)
2187 return boolean_false_node
;
2189 /* Otherwise, they may or may not be different. */
2193 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
2197 /* If VR0 is to the left of VR1, return true. */
2198 tst
= compare_values (vr0
->max
, vr1
->min
);
2199 if ((comp
== LT_EXPR
&& tst
== -1)
2200 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
2201 return boolean_true_node
;
2203 /* If VR0 is to the right of VR1, return false. */
2204 tst
= compare_values (vr0
->min
, vr1
->max
);
2205 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
2206 || (comp
== LE_EXPR
&& tst
== 1))
2207 return boolean_false_node
;
2209 /* Otherwise, we don't know. */
2217 /* Given a value range VR, a value VAL and a comparison code COMP, return
2218 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2219 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2220 always returns false. Return NULL_TREE if it is not always
2221 possible to determine the value of the comparison. */
2224 compare_range_with_value (enum tree_code comp
, value_range_t
*vr
, tree val
)
2226 if (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
)
2229 /* Anti-ranges need to be handled separately. */
2230 if (vr
->type
== VR_ANTI_RANGE
)
2232 /* For anti-ranges, the only predicates that we can compute at
2233 compile time are equality and inequality. */
2240 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2241 if (value_inside_range (val
, vr
) == 1)
2242 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
2247 if (comp
== EQ_EXPR
)
2249 /* EQ_EXPR may only be computed if VR represents exactly
2251 if (compare_values (vr
->min
, vr
->max
) == 0)
2253 int cmp
= compare_values (vr
->min
, val
);
2255 return boolean_true_node
;
2256 else if (cmp
== -1 || cmp
== 1 || cmp
== 2)
2257 return boolean_false_node
;
2259 else if (compare_values (val
, vr
->min
) == -1
2260 || compare_values (vr
->max
, val
) == -1)
2261 return boolean_false_node
;
2265 else if (comp
== NE_EXPR
)
2267 /* If VAL is not inside VR, then they are always different. */
2268 if (compare_values (vr
->max
, val
) == -1
2269 || compare_values (vr
->min
, val
) == 1)
2270 return boolean_true_node
;
2272 /* If VR represents exactly one value equal to VAL, then return
2274 if (compare_values (vr
->min
, vr
->max
) == 0
2275 && compare_values (vr
->min
, val
) == 0)
2276 return boolean_false_node
;
2278 /* Otherwise, they may or may not be different. */
2281 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
2285 /* If VR is to the left of VAL, return true. */
2286 tst
= compare_values (vr
->max
, val
);
2287 if ((comp
== LT_EXPR
&& tst
== -1)
2288 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
2289 return boolean_true_node
;
2291 /* If VR is to the right of VAL, return false. */
2292 tst
= compare_values (vr
->min
, val
);
2293 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
2294 || (comp
== LE_EXPR
&& tst
== 1))
2295 return boolean_false_node
;
2297 /* Otherwise, we don't know. */
2300 else if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
2304 /* If VR is to the right of VAL, return true. */
2305 tst
= compare_values (vr
->min
, val
);
2306 if ((comp
== GT_EXPR
&& tst
== 1)
2307 || (comp
== GE_EXPR
&& (tst
== 0 || tst
== 1)))
2308 return boolean_true_node
;
2310 /* If VR is to the left of VAL, return false. */
2311 tst
= compare_values (vr
->max
, val
);
2312 if ((comp
== GT_EXPR
&& (tst
== -1 || tst
== 0))
2313 || (comp
== GE_EXPR
&& tst
== -1))
2314 return boolean_false_node
;
2316 /* Otherwise, we don't know. */
2324 /* Debugging dumps. */
2326 void dump_value_range (FILE *, value_range_t
*);
2327 void debug_value_range (value_range_t
*);
2328 void dump_all_value_ranges (FILE *);
2329 void debug_all_value_ranges (void);
2330 void dump_vr_equiv (FILE *, bitmap
);
2331 void debug_vr_equiv (bitmap
);
2334 /* Dump value range VR to FILE. */
2337 dump_value_range (FILE *file
, value_range_t
*vr
)
2340 fprintf (file
, "[]");
2341 else if (vr
->type
== VR_UNDEFINED
)
2342 fprintf (file
, "UNDEFINED");
2343 else if (vr
->type
== VR_RANGE
|| vr
->type
== VR_ANTI_RANGE
)
2345 tree type
= TREE_TYPE (vr
->min
);
2347 fprintf (file
, "%s[", (vr
->type
== VR_ANTI_RANGE
) ? "~" : "");
2349 if (INTEGRAL_TYPE_P (type
)
2350 && !TYPE_UNSIGNED (type
)
2351 && vr
->min
== TYPE_MIN_VALUE (type
))
2352 fprintf (file
, "-INF");
2354 print_generic_expr (file
, vr
->min
, 0);
2356 fprintf (file
, ", ");
2358 if (INTEGRAL_TYPE_P (type
)
2359 && vr
->max
== TYPE_MAX_VALUE (type
))
2360 fprintf (file
, "+INF");
2362 print_generic_expr (file
, vr
->max
, 0);
2364 fprintf (file
, "]");
2371 fprintf (file
, " EQUIVALENCES: { ");
2373 EXECUTE_IF_SET_IN_BITMAP (vr
->equiv
, 0, i
, bi
)
2375 print_generic_expr (file
, ssa_name (i
), 0);
2376 fprintf (file
, " ");
2380 fprintf (file
, "} (%u elements)", c
);
2383 else if (vr
->type
== VR_VARYING
)
2384 fprintf (file
, "VARYING");
2386 fprintf (file
, "INVALID RANGE");
2390 /* Dump value range VR to stderr. */
2393 debug_value_range (value_range_t
*vr
)
2395 dump_value_range (stderr
, vr
);
2396 fprintf (stderr
, "\n");
2400 /* Dump value ranges of all SSA_NAMEs to FILE. */
2403 dump_all_value_ranges (FILE *file
)
2407 for (i
= 0; i
< num_ssa_names
; i
++)
2411 print_generic_expr (file
, ssa_name (i
), 0);
2412 fprintf (file
, ": ");
2413 dump_value_range (file
, vr_value
[i
]);
2414 fprintf (file
, "\n");
2418 fprintf (file
, "\n");
2422 /* Dump all value ranges to stderr. */
2425 debug_all_value_ranges (void)
2427 dump_all_value_ranges (stderr
);
2431 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
2432 create a new SSA name N and return the assertion assignment
2433 'V = ASSERT_EXPR <V, V OP W>'. */
2436 build_assert_expr_for (tree cond
, tree v
)
2440 gcc_assert (TREE_CODE (v
) == SSA_NAME
);
2441 n
= duplicate_ssa_name (v
, NULL_TREE
);
2443 if (COMPARISON_CLASS_P (cond
))
2445 tree a
= build2 (ASSERT_EXPR
, TREE_TYPE (v
), v
, cond
);
2446 assertion
= build2 (GIMPLE_MODIFY_STMT
, TREE_TYPE (v
), n
, a
);
2448 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
)
2450 /* Given !V, build the assignment N = false. */
2451 tree op0
= TREE_OPERAND (cond
, 0);
2452 gcc_assert (op0
== v
);
2453 assertion
= build2 (GIMPLE_MODIFY_STMT
, TREE_TYPE (v
), n
,
2454 boolean_false_node
);
2456 else if (TREE_CODE (cond
) == SSA_NAME
)
2458 /* Given V, build the assignment N = true. */
2459 gcc_assert (v
== cond
);
2460 assertion
= build2 (GIMPLE_MODIFY_STMT
,
2461 TREE_TYPE (v
), n
, boolean_true_node
);
2466 SSA_NAME_DEF_STMT (n
) = assertion
;
2468 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
2469 operand of the ASSERT_EXPR. Register the new name and the old one
2470 in the replacement table so that we can fix the SSA web after
2471 adding all the ASSERT_EXPRs. */
2472 register_new_name_mapping (n
, v
);
2478 /* Return false if EXPR is a predicate expression involving floating
2482 fp_predicate (tree expr
)
2484 return (COMPARISON_CLASS_P (expr
)
2485 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr
, 0))));
2489 /* If the range of values taken by OP can be inferred after STMT executes,
2490 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2491 describes the inferred range. Return true if a range could be
2495 infer_value_range (tree stmt
, tree op
, enum tree_code
*comp_code_p
, tree
*val_p
)
2498 *comp_code_p
= ERROR_MARK
;
2500 /* Do not attempt to infer anything in names that flow through
2502 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op
))
2505 /* Similarly, don't infer anything from statements that may throw
2507 if (tree_could_throw_p (stmt
))
2510 /* If STMT is the last statement of a basic block with no
2511 successors, there is no point inferring anything about any of its
2512 operands. We would not be able to find a proper insertion point
2513 for the assertion, anyway. */
2514 if (stmt_ends_bb_p (stmt
) && EDGE_COUNT (bb_for_stmt (stmt
)->succs
) == 0)
2517 /* We can only assume that a pointer dereference will yield
2518 non-NULL if -fdelete-null-pointer-checks is enabled. */
2519 if (flag_delete_null_pointer_checks
&& POINTER_TYPE_P (TREE_TYPE (op
)))
2522 unsigned num_uses
, num_derefs
;
2524 count_uses_and_derefs (op
, stmt
, &num_uses
, &num_derefs
, &is_store
);
2527 *val_p
= build_int_cst (TREE_TYPE (op
), 0);
2528 *comp_code_p
= NE_EXPR
;
2537 void dump_asserts_for (FILE *, tree
);
2538 void debug_asserts_for (tree
);
2539 void dump_all_asserts (FILE *);
2540 void debug_all_asserts (void);
2542 /* Dump all the registered assertions for NAME to FILE. */
2545 dump_asserts_for (FILE *file
, tree name
)
2549 fprintf (file
, "Assertions to be inserted for ");
2550 print_generic_expr (file
, name
, 0);
2551 fprintf (file
, "\n");
2553 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
2556 fprintf (file
, "\t");
2557 print_generic_expr (file
, bsi_stmt (loc
->si
), 0);
2558 fprintf (file
, "\n\tBB #%d", loc
->bb
->index
);
2561 fprintf (file
, "\n\tEDGE %d->%d", loc
->e
->src
->index
,
2562 loc
->e
->dest
->index
);
2563 dump_edge_info (file
, loc
->e
, 0);
2565 fprintf (file
, "\n\tPREDICATE: ");
2566 print_generic_expr (file
, name
, 0);
2567 fprintf (file
, " %s ", tree_code_name
[(int)loc
->comp_code
]);
2568 print_generic_expr (file
, loc
->val
, 0);
2569 fprintf (file
, "\n\n");
2573 fprintf (file
, "\n");
2577 /* Dump all the registered assertions for NAME to stderr. */
2580 debug_asserts_for (tree name
)
2582 dump_asserts_for (stderr
, name
);
2586 /* Dump all the registered assertions for all the names to FILE. */
2589 dump_all_asserts (FILE *file
)
2594 fprintf (file
, "\nASSERT_EXPRs to be inserted\n\n");
2595 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
2596 dump_asserts_for (file
, ssa_name (i
));
2597 fprintf (file
, "\n");
2601 /* Dump all the registered assertions for all the names to stderr. */
2604 debug_all_asserts (void)
2606 dump_all_asserts (stderr
);
2610 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2611 'NAME COMP_CODE VAL' at a location that dominates block BB or
2612 E->DEST, then register this location as a possible insertion point
2613 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2615 BB, E and SI provide the exact insertion point for the new
2616 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2617 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2618 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2619 must not be NULL. */
2622 register_new_assert_for (tree name
,
2623 enum tree_code comp_code
,
2627 block_stmt_iterator si
)
2629 assert_locus_t n
, loc
, last_loc
;
2631 basic_block dest_bb
;
2633 #if defined ENABLE_CHECKING
2634 gcc_assert (bb
== NULL
|| e
== NULL
);
2637 gcc_assert (TREE_CODE (bsi_stmt (si
)) != COND_EXPR
2638 && TREE_CODE (bsi_stmt (si
)) != SWITCH_EXPR
);
2641 /* The new assertion A will be inserted at BB or E. We need to
2642 determine if the new location is dominated by a previously
2643 registered location for A. If we are doing an edge insertion,
2644 assume that A will be inserted at E->DEST. Note that this is not
2647 If E is a critical edge, it will be split. But even if E is
2648 split, the new block will dominate the same set of blocks that
2651 The reverse, however, is not true, blocks dominated by E->DEST
2652 will not be dominated by the new block created to split E. So,
2653 if the insertion location is on a critical edge, we will not use
2654 the new location to move another assertion previously registered
2655 at a block dominated by E->DEST. */
2656 dest_bb
= (bb
) ? bb
: e
->dest
;
2658 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2659 VAL at a block dominating DEST_BB, then we don't need to insert a new
2660 one. Similarly, if the same assertion already exists at a block
2661 dominated by DEST_BB and the new location is not on a critical
2662 edge, then update the existing location for the assertion (i.e.,
2663 move the assertion up in the dominance tree).
2665 Note, this is implemented as a simple linked list because there
2666 should not be more than a handful of assertions registered per
2667 name. If this becomes a performance problem, a table hashed by
2668 COMP_CODE and VAL could be implemented. */
2669 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
2674 if (loc
->comp_code
== comp_code
2676 || operand_equal_p (loc
->val
, val
, 0)))
2678 /* If the assertion NAME COMP_CODE VAL has already been
2679 registered at a basic block that dominates DEST_BB, then
2680 we don't need to insert the same assertion again. Note
2681 that we don't check strict dominance here to avoid
2682 replicating the same assertion inside the same basic
2683 block more than once (e.g., when a pointer is
2684 dereferenced several times inside a block).
2686 An exception to this rule are edge insertions. If the
2687 new assertion is to be inserted on edge E, then it will
2688 dominate all the other insertions that we may want to
2689 insert in DEST_BB. So, if we are doing an edge
2690 insertion, don't do this dominance check. */
2692 && dominated_by_p (CDI_DOMINATORS
, dest_bb
, loc
->bb
))
2695 /* Otherwise, if E is not a critical edge and DEST_BB
2696 dominates the existing location for the assertion, move
2697 the assertion up in the dominance tree by updating its
2698 location information. */
2699 if ((e
== NULL
|| !EDGE_CRITICAL_P (e
))
2700 && dominated_by_p (CDI_DOMINATORS
, loc
->bb
, dest_bb
))
2709 /* Update the last node of the list and move to the next one. */
2714 /* If we didn't find an assertion already registered for
2715 NAME COMP_CODE VAL, add a new one at the end of the list of
2716 assertions associated with NAME. */
2717 n
= XNEW (struct assert_locus_d
);
2721 n
->comp_code
= comp_code
;
2728 asserts_for
[SSA_NAME_VERSION (name
)] = n
;
2730 bitmap_set_bit (need_assert_for
, SSA_NAME_VERSION (name
));
2733 /* COND is a predicate which uses NAME. Extract a suitable test code
2734 and value and store them into *CODE_P and *VAL_P so the predicate
2735 is normalized to NAME *CODE_P *VAL_P.
2737 If no extraction was possible, return FALSE, otherwise return TRUE.
2739 If INVERT is true, then we invert the result stored into *CODE_P. */
2742 extract_code_and_val_from_cond (tree name
, tree cond
, bool invert
,
2743 enum tree_code
*code_p
, tree
*val_p
)
2745 enum tree_code comp_code
;
2748 /* Predicates may be a single SSA name or NAME OP VAL. */
2751 /* If the predicate is a name, it must be NAME, in which
2752 case we create the predicate NAME == true or
2753 NAME == false accordingly. */
2754 comp_code
= EQ_EXPR
;
2755 val
= invert
? boolean_false_node
: boolean_true_node
;
2759 /* Otherwise, we have a comparison of the form NAME COMP VAL
2760 or VAL COMP NAME. */
2761 if (name
== TREE_OPERAND (cond
, 1))
2763 /* If the predicate is of the form VAL COMP NAME, flip
2764 COMP around because we need to register NAME as the
2765 first operand in the predicate. */
2766 comp_code
= swap_tree_comparison (TREE_CODE (cond
));
2767 val
= TREE_OPERAND (cond
, 0);
2771 /* The comparison is of the form NAME COMP VAL, so the
2772 comparison code remains unchanged. */
2773 comp_code
= TREE_CODE (cond
);
2774 val
= TREE_OPERAND (cond
, 1);
2777 /* Invert the comparison code as necessary. */
2779 comp_code
= invert_tree_comparison (comp_code
, 0);
2781 /* VRP does not handle float types. */
2782 if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val
)))
2785 /* Do not register always-false predicates.
2786 FIXME: this works around a limitation in fold() when dealing with
2787 enumerations. Given 'enum { N1, N2 } x;', fold will not
2788 fold 'if (x > N2)' to 'if (0)'. */
2789 if ((comp_code
== GT_EXPR
|| comp_code
== LT_EXPR
)
2790 && INTEGRAL_TYPE_P (TREE_TYPE (val
)))
2792 tree min
= TYPE_MIN_VALUE (TREE_TYPE (val
));
2793 tree max
= TYPE_MAX_VALUE (TREE_TYPE (val
));
2795 if (comp_code
== GT_EXPR
2797 || compare_values (val
, max
) == 0))
2800 if (comp_code
== LT_EXPR
2802 || compare_values (val
, min
) == 0))
2806 *code_p
= comp_code
;
2811 /* OP is an operand of a truth value expression which is known to have
2812 a particular value. Register any asserts for OP and for any
2813 operands in OP's defining statement.
2815 If CODE is EQ_EXPR, then we want to register OP is zero (false),
2816 if CODE is NE_EXPR, then we want to register OP is nonzero (true). */
2819 register_edge_assert_for_1 (tree op
, enum tree_code code
,
2820 edge e
, block_stmt_iterator bsi
)
2822 bool retval
= false;
2823 tree op_def
, rhs
, val
;
2825 /* We only care about SSA_NAMEs. */
2826 if (TREE_CODE (op
) != SSA_NAME
)
2829 /* We know that OP will have a zero or nonzero value. If OP is used
2830 more than once go ahead and register an assert for OP.
2832 The FOUND_IN_SUBGRAPH support is not helpful in this situation as
2833 it will always be set for OP (because OP is used in a COND_EXPR in
2835 if (!has_single_use (op
))
2837 val
= build_int_cst (TREE_TYPE (op
), 0);
2838 register_new_assert_for (op
, code
, val
, NULL
, e
, bsi
);
2842 /* Now look at how OP is set. If it's set from a comparison,
2843 a truth operation or some bit operations, then we may be able
2844 to register information about the operands of that assignment. */
2845 op_def
= SSA_NAME_DEF_STMT (op
);
2846 if (TREE_CODE (op_def
) != GIMPLE_MODIFY_STMT
)
2849 rhs
= GIMPLE_STMT_OPERAND (op_def
, 1);
2851 if (COMPARISON_CLASS_P (rhs
))
2853 bool invert
= (code
== EQ_EXPR
? true : false);
2854 tree op0
= TREE_OPERAND (rhs
, 0);
2855 tree op1
= TREE_OPERAND (rhs
, 1);
2857 /* Conditionally register an assert for each SSA_NAME in the
2859 if (TREE_CODE (op0
) == SSA_NAME
2860 && !has_single_use (op0
)
2861 && extract_code_and_val_from_cond (op0
, rhs
,
2862 invert
, &code
, &val
))
2864 register_new_assert_for (op0
, code
, val
, NULL
, e
, bsi
);
2868 /* Similarly for the second operand of the comparison. */
2869 if (TREE_CODE (op1
) == SSA_NAME
2870 && !has_single_use (op1
)
2871 && extract_code_and_val_from_cond (op1
, rhs
,
2872 invert
, &code
, &val
))
2874 register_new_assert_for (op1
, code
, val
, NULL
, e
, bsi
);
2878 else if ((code
== NE_EXPR
2879 && (TREE_CODE (rhs
) == TRUTH_AND_EXPR
2880 || TREE_CODE (rhs
) == BIT_AND_EXPR
))
2882 && (TREE_CODE (rhs
) == TRUTH_OR_EXPR
2883 || TREE_CODE (rhs
) == BIT_IOR_EXPR
)))
2885 /* Recurse on each operand. */
2886 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 0),
2888 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 1),
2891 else if (TREE_CODE (rhs
) == TRUTH_NOT_EXPR
)
2893 /* Recurse, flipping CODE. */
2894 code
= invert_tree_comparison (code
, false);
2895 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 0),
2898 else if (TREE_CODE (rhs
) == SSA_NAME
)
2900 /* Recurse through the copy. */
2901 retval
|= register_edge_assert_for_1 (rhs
, code
, e
, bsi
);
2903 else if (TREE_CODE (rhs
) == NOP_EXPR
2904 || TREE_CODE (rhs
) == CONVERT_EXPR
2905 || TREE_CODE (rhs
) == VIEW_CONVERT_EXPR
2906 || TREE_CODE (rhs
) == NON_LVALUE_EXPR
)
2908 /* Recurse through the type conversion. */
2909 retval
|= register_edge_assert_for_1 (TREE_OPERAND (rhs
, 0),
2916 /* Try to register an edge assertion for SSA name NAME on edge E for
2917 the condition COND contributing to the conditional jump pointed to by SI.
2918 Return true if an assertion for NAME could be registered. */
2921 register_edge_assert_for (tree name
, edge e
, block_stmt_iterator si
, tree cond
)
2924 enum tree_code comp_code
;
2925 bool retval
= false;
2926 bool is_else_edge
= (e
->flags
& EDGE_FALSE_VALUE
) != 0;
2928 /* Do not attempt to infer anything in names that flow through
2930 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name
))
2933 if (!extract_code_and_val_from_cond (name
, cond
, is_else_edge
,
2937 /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
2938 reachable from E. */
2939 if (TEST_BIT (found_in_subgraph
, SSA_NAME_VERSION (name
)))
2941 register_new_assert_for (name
, comp_code
, val
, NULL
, e
, si
);
2945 /* If COND is effectively an equality test of an SSA_NAME against
2946 the value zero or one, then we may be able to assert values
2947 for SSA_NAMEs which flow into COND. */
2949 /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining
2950 statement of NAME we can assert both operands of the TRUTH_AND_EXPR
2951 have nonzero value. */
2952 if (((comp_code
== EQ_EXPR
&& integer_onep (val
))
2953 || (comp_code
== NE_EXPR
&& integer_zerop (val
))))
2955 tree def_stmt
= SSA_NAME_DEF_STMT (name
);
2957 if (TREE_CODE (def_stmt
) == GIMPLE_MODIFY_STMT
2958 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == TRUTH_AND_EXPR
2959 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == BIT_AND_EXPR
))
2961 tree op0
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 0);
2962 tree op1
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 1);
2963 retval
|= register_edge_assert_for_1 (op0
, NE_EXPR
, e
, si
);
2964 retval
|= register_edge_assert_for_1 (op1
, NE_EXPR
, e
, si
);
2968 /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining
2969 statement of NAME we can assert both operands of the TRUTH_OR_EXPR
2971 if (((comp_code
== EQ_EXPR
&& integer_zerop (val
))
2972 || (comp_code
== NE_EXPR
&& integer_onep (val
))))
2974 tree def_stmt
= SSA_NAME_DEF_STMT (name
);
2976 if (TREE_CODE (def_stmt
) == GIMPLE_MODIFY_STMT
2977 && (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == TRUTH_OR_EXPR
2978 || TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == BIT_IOR_EXPR
))
2980 tree op0
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 0);
2981 tree op1
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 1);
2982 retval
|= register_edge_assert_for_1 (op0
, EQ_EXPR
, e
, si
);
2983 retval
|= register_edge_assert_for_1 (op1
, EQ_EXPR
, e
, si
);
2991 static bool find_assert_locations (basic_block bb
);
2993 /* Determine whether the outgoing edges of BB should receive an
2994 ASSERT_EXPR for each of the operands of BB's LAST statement.
2995 The last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2997 If any of the sub-graphs rooted at BB have an interesting use of
2998 the predicate operands, an assert location node is added to the
2999 list of assertions for the corresponding operands. */
3002 find_conditional_asserts (basic_block bb
, tree last
)
3005 block_stmt_iterator bsi
;
3011 need_assert
= false;
3012 bsi
= bsi_for_stmt (last
);
3014 /* Look for uses of the operands in each of the sub-graphs
3015 rooted at BB. We need to check each of the outgoing edges
3016 separately, so that we know what kind of ASSERT_EXPR to
3018 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3023 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
3024 Otherwise, when we finish traversing each of the sub-graphs, we
3025 won't know whether the variables were found in the sub-graphs or
3026 if they had been found in a block upstream from BB.
3028 This is actually a bad idea is some cases, particularly jump
3029 threading. Consider a CFG like the following:
3039 Assume that one or more operands in the conditional at the
3040 end of block 0 are used in a conditional in block 2, but not
3041 anywhere in block 1. In this case we will not insert any
3042 assert statements in block 1, which may cause us to miss
3043 opportunities to optimize, particularly for jump threading. */
3044 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
3045 RESET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3047 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3048 to determine if any of the operands in the conditional
3049 predicate are used. */
3051 need_assert
|= find_assert_locations (e
->dest
);
3053 /* Register the necessary assertions for each operand in the
3054 conditional predicate. */
3055 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
3056 need_assert
|= register_edge_assert_for (op
, e
, bsi
,
3057 COND_EXPR_COND (last
));
3060 /* Finally, indicate that we have found the operands in the
3062 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
3063 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3069 /* Traverse all the statements in block BB looking for statements that
3070 may generate useful assertions for the SSA names in their operand.
3071 If a statement produces a useful assertion A for name N_i, then the
3072 list of assertions already generated for N_i is scanned to
3073 determine if A is actually needed.
3075 If N_i already had the assertion A at a location dominating the
3076 current location, then nothing needs to be done. Otherwise, the
3077 new location for A is recorded instead.
3079 1- For every statement S in BB, all the variables used by S are
3080 added to bitmap FOUND_IN_SUBGRAPH.
3082 2- If statement S uses an operand N in a way that exposes a known
3083 value range for N, then if N was not already generated by an
3084 ASSERT_EXPR, create a new assert location for N. For instance,
3085 if N is a pointer and the statement dereferences it, we can
3086 assume that N is not NULL.
3088 3- COND_EXPRs are a special case of #2. We can derive range
3089 information from the predicate but need to insert different
3090 ASSERT_EXPRs for each of the sub-graphs rooted at the
3091 conditional block. If the last statement of BB is a conditional
3092 expression of the form 'X op Y', then
3094 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
3096 b) If the conditional is the only entry point to the sub-graph
3097 corresponding to the THEN_CLAUSE, recurse into it. On
3098 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
3099 an ASSERT_EXPR is added for the corresponding variable.
3101 c) Repeat step (b) on the ELSE_CLAUSE.
3103 d) Mark X and Y in FOUND_IN_SUBGRAPH.
3112 In this case, an assertion on the THEN clause is useful to
3113 determine that 'a' is always 9 on that edge. However, an assertion
3114 on the ELSE clause would be unnecessary.
3116 4- If BB does not end in a conditional expression, then we recurse
3117 into BB's dominator children.
3119 At the end of the recursive traversal, every SSA name will have a
3120 list of locations where ASSERT_EXPRs should be added. When a new
3121 location for name N is found, it is registered by calling
3122 register_new_assert_for. That function keeps track of all the
3123 registered assertions to prevent adding unnecessary assertions.
3124 For instance, if a pointer P_4 is dereferenced more than once in a
3125 dominator tree, only the location dominating all the dereference of
3126 P_4 will receive an ASSERT_EXPR.
3128 If this function returns true, then it means that there are names
3129 for which we need to generate ASSERT_EXPRs. Those assertions are
3130 inserted by process_assert_insertions.
3132 TODO. Handle SWITCH_EXPR. */
3135 find_assert_locations (basic_block bb
)
3137 block_stmt_iterator si
;
3142 if (TEST_BIT (blocks_visited
, bb
->index
))
3145 SET_BIT (blocks_visited
, bb
->index
);
3147 need_assert
= false;
3149 /* Traverse all PHI nodes in BB marking used operands. */
3150 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3152 use_operand_p arg_p
;
3155 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_USE
)
3157 tree arg
= USE_FROM_PTR (arg_p
);
3158 if (TREE_CODE (arg
) == SSA_NAME
)
3160 gcc_assert (is_gimple_reg (PHI_RESULT (phi
)));
3161 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (arg
));
3166 /* Traverse all the statements in BB marking used names and looking
3167 for statements that may infer assertions for their used operands. */
3169 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
3174 stmt
= bsi_stmt (si
);
3176 /* See if we can derive an assertion for any of STMT's operands. */
3177 FOR_EACH_SSA_TREE_OPERAND (op
, stmt
, i
, SSA_OP_USE
)
3180 enum tree_code comp_code
;
3182 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
3183 the sub-graph of a conditional block, when we return from
3184 this recursive walk, our parent will use the
3185 FOUND_IN_SUBGRAPH bitset to determine if one of the
3186 operands it was looking for was present in the sub-graph. */
3187 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3189 /* If OP is used in such a way that we can infer a value
3190 range for it, and we don't find a previous assertion for
3191 it, create a new assertion location node for OP. */
3192 if (infer_value_range (stmt
, op
, &comp_code
, &value
))
3194 /* If we are able to infer a nonzero value range for OP,
3195 then walk backwards through the use-def chain to see if OP
3196 was set via a typecast.
3198 If so, then we can also infer a nonzero value range
3199 for the operand of the NOP_EXPR. */
3200 if (comp_code
== NE_EXPR
&& integer_zerop (value
))
3203 tree def_stmt
= SSA_NAME_DEF_STMT (t
);
3205 while (TREE_CODE (def_stmt
) == GIMPLE_MODIFY_STMT
3207 (GIMPLE_STMT_OPERAND (def_stmt
, 1)) == NOP_EXPR
3209 (TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1),
3212 (TREE_TYPE (TREE_OPERAND
3213 (GIMPLE_STMT_OPERAND (def_stmt
,
3216 t
= TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt
, 1), 0);
3217 def_stmt
= SSA_NAME_DEF_STMT (t
);
3219 /* Note we want to register the assert for the
3220 operand of the NOP_EXPR after SI, not after the
3222 if (! has_single_use (t
))
3224 register_new_assert_for (t
, comp_code
, value
,
3231 /* If OP is used only once, namely in this STMT, don't
3232 bother creating an ASSERT_EXPR for it. Such an
3233 ASSERT_EXPR would do nothing but increase compile time. */
3234 if (!has_single_use (op
))
3236 register_new_assert_for (op
, comp_code
, value
, bb
, NULL
, si
);
3242 /* Remember the last statement of the block. */
3246 /* If BB's last statement is a conditional expression
3247 involving integer operands, recurse into each of the sub-graphs
3248 rooted at BB to determine if we need to add ASSERT_EXPRs. */
3250 && TREE_CODE (last
) == COND_EXPR
3251 && !fp_predicate (COND_EXPR_COND (last
))
3252 && !ZERO_SSA_OPERANDS (last
, SSA_OP_USE
))
3253 need_assert
|= find_conditional_asserts (bb
, last
);
3255 /* Recurse into the dominator children of BB. */
3256 for (son
= first_dom_son (CDI_DOMINATORS
, bb
);
3258 son
= next_dom_son (CDI_DOMINATORS
, son
))
3259 need_assert
|= find_assert_locations (son
);
3265 /* Create an ASSERT_EXPR for NAME and insert it in the location
3266 indicated by LOC. Return true if we made any edge insertions. */
3269 process_assert_insertions_for (tree name
, assert_locus_t loc
)
3271 /* Build the comparison expression NAME_i COMP_CODE VAL. */
3272 tree stmt
, cond
, assert_expr
;
3276 cond
= build2 (loc
->comp_code
, boolean_type_node
, name
, loc
->val
);
3277 assert_expr
= build_assert_expr_for (cond
, name
);
3281 /* We have been asked to insert the assertion on an edge. This
3282 is used only by COND_EXPR and SWITCH_EXPR assertions. */
3283 #if defined ENABLE_CHECKING
3284 gcc_assert (TREE_CODE (bsi_stmt (loc
->si
)) == COND_EXPR
3285 || TREE_CODE (bsi_stmt (loc
->si
)) == SWITCH_EXPR
);
3288 bsi_insert_on_edge (loc
->e
, assert_expr
);
3292 /* Otherwise, we can insert right after LOC->SI iff the
3293 statement must not be the last statement in the block. */
3294 stmt
= bsi_stmt (loc
->si
);
3295 if (!stmt_ends_bb_p (stmt
))
3297 bsi_insert_after (&loc
->si
, assert_expr
, BSI_SAME_STMT
);
3301 /* If STMT must be the last statement in BB, we can only insert new
3302 assertions on the non-abnormal edge out of BB. Note that since
3303 STMT is not control flow, there may only be one non-abnormal edge
3305 FOR_EACH_EDGE (e
, ei
, loc
->bb
->succs
)
3306 if (!(e
->flags
& EDGE_ABNORMAL
))
3308 bsi_insert_on_edge (e
, assert_expr
);
3316 /* Process all the insertions registered for every name N_i registered
3317 in NEED_ASSERT_FOR. The list of assertions to be inserted are
3318 found in ASSERTS_FOR[i]. */
3321 process_assert_insertions (void)
3325 bool update_edges_p
= false;
3326 int num_asserts
= 0;
3328 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3329 dump_all_asserts (dump_file
);
3331 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
3333 assert_locus_t loc
= asserts_for
[i
];
3338 assert_locus_t next
= loc
->next
;
3339 update_edges_p
|= process_assert_insertions_for (ssa_name (i
), loc
);
3347 bsi_commit_edge_inserts ();
3349 if (dump_file
&& (dump_flags
& TDF_STATS
))
3350 fprintf (dump_file
, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
3355 /* Traverse the flowgraph looking for conditional jumps to insert range
3356 expressions. These range expressions are meant to provide information
3357 to optimizations that need to reason in terms of value ranges. They
3358 will not be expanded into RTL. For instance, given:
3367 this pass will transform the code into:
3373 x = ASSERT_EXPR <x, x < y>
3378 y = ASSERT_EXPR <y, x <= y>
3382 The idea is that once copy and constant propagation have run, other
3383 optimizations will be able to determine what ranges of values can 'x'
3384 take in different paths of the code, simply by checking the reaching
3385 definition of 'x'. */
3388 insert_range_assertions (void)
3394 found_in_subgraph
= sbitmap_alloc (num_ssa_names
);
3395 sbitmap_zero (found_in_subgraph
);
3397 blocks_visited
= sbitmap_alloc (last_basic_block
);
3398 sbitmap_zero (blocks_visited
);
3400 need_assert_for
= BITMAP_ALLOC (NULL
);
3401 asserts_for
= XCNEWVEC (assert_locus_t
, num_ssa_names
);
3403 calculate_dominance_info (CDI_DOMINATORS
);
3405 update_ssa_p
= false;
3406 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
3407 if (find_assert_locations (e
->dest
))
3408 update_ssa_p
= true;
3412 process_assert_insertions ();
3413 update_ssa (TODO_update_ssa_no_phi
);
3416 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3418 fprintf (dump_file
, "\nSSA form after inserting ASSERT_EXPRs\n");
3419 dump_function_to_file (current_function_decl
, dump_file
, dump_flags
);
3422 sbitmap_free (found_in_subgraph
);
3424 BITMAP_FREE (need_assert_for
);
3428 /* Convert range assertion expressions into the implied copies and
3429 copy propagate away the copies. Doing the trivial copy propagation
3430 here avoids the need to run the full copy propagation pass after
3433 FIXME, this will eventually lead to copy propagation removing the
3434 names that had useful range information attached to them. For
3435 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
3436 then N_i will have the range [3, +INF].
3438 However, by converting the assertion into the implied copy
3439 operation N_i = N_j, we will then copy-propagate N_j into the uses
3440 of N_i and lose the range information. We may want to hold on to
3441 ASSERT_EXPRs a little while longer as the ranges could be used in
3442 things like jump threading.
3444 The problem with keeping ASSERT_EXPRs around is that passes after
3445 VRP need to handle them appropriately.
3447 Another approach would be to make the range information a first
3448 class property of the SSA_NAME so that it can be queried from
3449 any pass. This is made somewhat more complex by the need for
3450 multiple ranges to be associated with one SSA_NAME. */
3453 remove_range_assertions (void)
3456 block_stmt_iterator si
;
3458 /* Note that the BSI iterator bump happens at the bottom of the
3459 loop and no bump is necessary if we're removing the statement
3460 referenced by the current BSI. */
3462 for (si
= bsi_start (bb
); !bsi_end_p (si
);)
3464 tree stmt
= bsi_stmt (si
);
3467 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
3468 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt
, 1)) == ASSERT_EXPR
)
3470 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1), var
;
3471 tree cond
= fold (ASSERT_EXPR_COND (rhs
));
3472 use_operand_p use_p
;
3473 imm_use_iterator iter
;
3475 gcc_assert (cond
!= boolean_false_node
);
3477 /* Propagate the RHS into every use of the LHS. */
3478 var
= ASSERT_EXPR_VAR (rhs
);
3479 FOR_EACH_IMM_USE_STMT (use_stmt
, iter
,
3480 GIMPLE_STMT_OPERAND (stmt
, 0))
3481 FOR_EACH_IMM_USE_ON_STMT (use_p
, iter
)
3483 SET_USE (use_p
, var
);
3484 gcc_assert (TREE_CODE (var
) == SSA_NAME
);
3487 /* And finally, remove the copy, it is not needed. */
3488 bsi_remove (&si
, true);
3494 sbitmap_free (blocks_visited
);
3498 /* Return true if STMT is interesting for VRP. */
3501 stmt_interesting_for_vrp (tree stmt
)
3503 if (TREE_CODE (stmt
) == PHI_NODE
3504 && is_gimple_reg (PHI_RESULT (stmt
))
3505 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))
3506 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))))
3508 else if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
3510 tree lhs
= GIMPLE_STMT_OPERAND (stmt
, 0);
3511 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
3513 /* In general, assignments with virtual operands are not useful
3514 for deriving ranges, with the obvious exception of calls to
3515 builtin functions. */
3516 if (TREE_CODE (lhs
) == SSA_NAME
3517 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
3518 || POINTER_TYPE_P (TREE_TYPE (lhs
)))
3519 && ((TREE_CODE (rhs
) == CALL_EXPR
3520 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == ADDR_EXPR
3521 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0))
3522 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0)))
3523 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
)))
3526 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
3533 /* Initialize local data structures for VRP. */
3536 vrp_initialize (void)
3540 vr_value
= XCNEWVEC (value_range_t
*, num_ssa_names
);
3544 block_stmt_iterator si
;
3547 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3549 if (!stmt_interesting_for_vrp (phi
))
3551 tree lhs
= PHI_RESULT (phi
);
3552 set_value_range_to_varying (get_value_range (lhs
));
3553 DONT_SIMULATE_AGAIN (phi
) = true;
3556 DONT_SIMULATE_AGAIN (phi
) = false;
3559 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
3561 tree stmt
= bsi_stmt (si
);
3563 if (!stmt_interesting_for_vrp (stmt
))
3567 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, i
, SSA_OP_DEF
)
3568 set_value_range_to_varying (get_value_range (def
));
3569 DONT_SIMULATE_AGAIN (stmt
) = true;
3573 DONT_SIMULATE_AGAIN (stmt
) = false;
3580 /* Visit assignment STMT. If it produces an interesting range, record
3581 the SSA name in *OUTPUT_P. */
3583 static enum ssa_prop_result
3584 vrp_visit_assignment (tree stmt
, tree
*output_p
)
3589 lhs
= GIMPLE_STMT_OPERAND (stmt
, 0);
3590 rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
3592 /* We only keep track of ranges in integral and pointer types. */
3593 if (TREE_CODE (lhs
) == SSA_NAME
3594 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
3595 /* It is valid to have NULL MIN/MAX values on a type. See
3596 build_range_type. */
3597 && TYPE_MIN_VALUE (TREE_TYPE (lhs
))
3598 && TYPE_MAX_VALUE (TREE_TYPE (lhs
)))
3599 || POINTER_TYPE_P (TREE_TYPE (lhs
))))
3602 value_range_t new_vr
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
3604 extract_range_from_expr (&new_vr
, rhs
);
3606 /* If STMT is inside a loop, we may be able to know something
3607 else about the range of LHS by examining scalar evolution
3609 if (current_loops
&& (l
= loop_containing_stmt (stmt
)))
3610 adjust_range_with_scev (&new_vr
, l
, stmt
, lhs
);
3612 if (update_value_range (lhs
, &new_vr
))
3616 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3618 fprintf (dump_file
, "Found new range for ");
3619 print_generic_expr (dump_file
, lhs
, 0);
3620 fprintf (dump_file
, ": ");
3621 dump_value_range (dump_file
, &new_vr
);
3622 fprintf (dump_file
, "\n\n");
3625 if (new_vr
.type
== VR_VARYING
)
3626 return SSA_PROP_VARYING
;
3628 return SSA_PROP_INTERESTING
;
3631 return SSA_PROP_NOT_INTERESTING
;
3634 /* Every other statement produces no useful ranges. */
3635 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
3636 set_value_range_to_varying (get_value_range (def
));
3638 return SSA_PROP_VARYING
;
3642 /* Compare all the value ranges for names equivalent to VAR with VAL
3643 using comparison code COMP. Return the same value returned by
3644 compare_range_with_value. */
3647 compare_name_with_value (enum tree_code comp
, tree var
, tree val
)
3654 t
= retval
= NULL_TREE
;
3656 /* Get the set of equivalences for VAR. */
3657 e
= get_value_range (var
)->equiv
;
3659 /* Add VAR to its own set of equivalences so that VAR's value range
3660 is processed by this loop (otherwise, we would have to replicate
3661 the body of the loop just to check VAR's value range). */
3662 bitmap_set_bit (e
, SSA_NAME_VERSION (var
));
3664 EXECUTE_IF_SET_IN_BITMAP (e
, 0, i
, bi
)
3666 value_range_t equiv_vr
= *(vr_value
[i
]);
3668 /* If name N_i does not have a valid range, use N_i as its own
3669 range. This allows us to compare against names that may
3670 have N_i in their ranges. */
3671 if (equiv_vr
.type
== VR_VARYING
|| equiv_vr
.type
== VR_UNDEFINED
)
3673 equiv_vr
.type
= VR_RANGE
;
3674 equiv_vr
.min
= ssa_name (i
);
3675 equiv_vr
.max
= ssa_name (i
);
3678 t
= compare_range_with_value (comp
, &equiv_vr
, val
);
3681 /* If we get different answers from different members
3682 of the equivalence set this check must be in a dead
3683 code region. Folding it to a trap representation
3684 would be correct here. For now just return don't-know. */
3695 /* Remove VAR from its own equivalence set. */
3696 bitmap_clear_bit (e
, SSA_NAME_VERSION (var
));
3701 /* We couldn't find a non-NULL value for the predicate. */
3706 /* Given a comparison code COMP and names N1 and N2, compare all the
3707 ranges equivalent to N1 against all the ranges equivalent to N2
3708 to determine the value of N1 COMP N2. Return the same value
3709 returned by compare_ranges. */
3712 compare_names (enum tree_code comp
, tree n1
, tree n2
)
3716 bitmap_iterator bi1
, bi2
;
3719 /* Compare the ranges of every name equivalent to N1 against the
3720 ranges of every name equivalent to N2. */
3721 e1
= get_value_range (n1
)->equiv
;
3722 e2
= get_value_range (n2
)->equiv
;
3724 /* Add N1 and N2 to their own set of equivalences to avoid
3725 duplicating the body of the loop just to check N1 and N2
3727 bitmap_set_bit (e1
, SSA_NAME_VERSION (n1
));
3728 bitmap_set_bit (e2
, SSA_NAME_VERSION (n2
));
3730 /* If the equivalence sets have a common intersection, then the two
3731 names can be compared without checking their ranges. */
3732 if (bitmap_intersect_p (e1
, e2
))
3734 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3735 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3737 return (comp
== EQ_EXPR
|| comp
== GE_EXPR
|| comp
== LE_EXPR
)
3739 : boolean_false_node
;
3742 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3743 N2 to their own set of equivalences to avoid duplicating the body
3744 of the loop just to check N1 and N2 ranges. */
3745 EXECUTE_IF_SET_IN_BITMAP (e1
, 0, i1
, bi1
)
3747 value_range_t vr1
= *(vr_value
[i1
]);
3749 /* If the range is VARYING or UNDEFINED, use the name itself. */
3750 if (vr1
.type
== VR_VARYING
|| vr1
.type
== VR_UNDEFINED
)
3752 vr1
.type
= VR_RANGE
;
3753 vr1
.min
= ssa_name (i1
);
3754 vr1
.max
= ssa_name (i1
);
3757 t
= retval
= NULL_TREE
;
3758 EXECUTE_IF_SET_IN_BITMAP (e2
, 0, i2
, bi2
)
3760 value_range_t vr2
= *(vr_value
[i2
]);
3762 if (vr2
.type
== VR_VARYING
|| vr2
.type
== VR_UNDEFINED
)
3764 vr2
.type
= VR_RANGE
;
3765 vr2
.min
= ssa_name (i2
);
3766 vr2
.max
= ssa_name (i2
);
3769 t
= compare_ranges (comp
, &vr1
, &vr2
);
3772 /* If we get different answers from different members
3773 of the equivalence set this check must be in a dead
3774 code region. Folding it to a trap representation
3775 would be correct here. For now just return don't-know. */
3779 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3780 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3789 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3790 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3795 /* None of the equivalent ranges are useful in computing this
3797 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3798 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3803 /* Given a conditional predicate COND, try to determine if COND yields
3804 true or false based on the value ranges of its operands. Return
3805 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3806 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3807 NULL if the conditional cannot be evaluated at compile time.
3809 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3810 the operands in COND are used when trying to compute its value.
3811 This is only used during final substitution. During propagation,
3812 we only check the range of each variable and not its equivalents. */
3815 vrp_evaluate_conditional (tree cond
, bool use_equiv_p
)
3817 gcc_assert (TREE_CODE (cond
) == SSA_NAME
3818 || TREE_CODE_CLASS (TREE_CODE (cond
)) == tcc_comparison
);
3820 if (TREE_CODE (cond
) == SSA_NAME
)
3826 retval
= compare_name_with_value (NE_EXPR
, cond
, boolean_false_node
);
3829 value_range_t
*vr
= get_value_range (cond
);
3830 retval
= compare_range_with_value (NE_EXPR
, vr
, boolean_false_node
);
3833 /* If COND has a known boolean range, return it. */
3837 /* Otherwise, if COND has a symbolic range of exactly one value,
3839 vr
= get_value_range (cond
);
3840 if (vr
->type
== VR_RANGE
&& vr
->min
== vr
->max
)
3845 tree op0
= TREE_OPERAND (cond
, 0);
3846 tree op1
= TREE_OPERAND (cond
, 1);
3848 /* We only deal with integral and pointer types. */
3849 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
3850 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
3855 if (TREE_CODE (op0
) == SSA_NAME
&& TREE_CODE (op1
) == SSA_NAME
)
3856 return compare_names (TREE_CODE (cond
), op0
, op1
);
3857 else if (TREE_CODE (op0
) == SSA_NAME
)
3858 return compare_name_with_value (TREE_CODE (cond
), op0
, op1
);
3859 else if (TREE_CODE (op1
) == SSA_NAME
)
3860 return compare_name_with_value (
3861 swap_tree_comparison (TREE_CODE (cond
)), op1
, op0
);
3865 value_range_t
*vr0
, *vr1
;
3867 vr0
= (TREE_CODE (op0
) == SSA_NAME
) ? get_value_range (op0
) : NULL
;
3868 vr1
= (TREE_CODE (op1
) == SSA_NAME
) ? get_value_range (op1
) : NULL
;
3871 return compare_ranges (TREE_CODE (cond
), vr0
, vr1
);
3872 else if (vr0
&& vr1
== NULL
)
3873 return compare_range_with_value (TREE_CODE (cond
), vr0
, op1
);
3874 else if (vr0
== NULL
&& vr1
)
3875 return compare_range_with_value (
3876 swap_tree_comparison (TREE_CODE (cond
)), vr1
, op0
);
3880 /* Anything else cannot be computed statically. */
3885 /* Visit conditional statement STMT. If we can determine which edge
3886 will be taken out of STMT's basic block, record it in
3887 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3888 SSA_PROP_VARYING. */
3890 static enum ssa_prop_result
3891 vrp_visit_cond_stmt (tree stmt
, edge
*taken_edge_p
)
3895 *taken_edge_p
= NULL
;
3897 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3898 add ASSERT_EXPRs for them. */
3899 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
3900 return SSA_PROP_VARYING
;
3902 cond
= COND_EXPR_COND (stmt
);
3904 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3909 fprintf (dump_file
, "\nVisiting conditional with predicate: ");
3910 print_generic_expr (dump_file
, cond
, 0);
3911 fprintf (dump_file
, "\nWith known ranges\n");
3913 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, i
, SSA_OP_USE
)
3915 fprintf (dump_file
, "\t");
3916 print_generic_expr (dump_file
, use
, 0);
3917 fprintf (dump_file
, ": ");
3918 dump_value_range (dump_file
, vr_value
[SSA_NAME_VERSION (use
)]);
3921 fprintf (dump_file
, "\n");
3924 /* Compute the value of the predicate COND by checking the known
3925 ranges of each of its operands.
3927 Note that we cannot evaluate all the equivalent ranges here
3928 because those ranges may not yet be final and with the current
3929 propagation strategy, we cannot determine when the value ranges
3930 of the names in the equivalence set have changed.
3932 For instance, given the following code fragment
3936 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3940 Assume that on the first visit to i_14, i_5 has the temporary
3941 range [8, 8] because the second argument to the PHI function is
3942 not yet executable. We derive the range ~[0, 0] for i_14 and the
3943 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3944 the first time, since i_14 is equivalent to the range [8, 8], we
3945 determine that the predicate is always false.
3947 On the next round of propagation, i_13 is determined to be
3948 VARYING, which causes i_5 to drop down to VARYING. So, another
3949 visit to i_14 is scheduled. In this second visit, we compute the
3950 exact same range and equivalence set for i_14, namely ~[0, 0] and
3951 { i_5 }. But we did not have the previous range for i_5
3952 registered, so vrp_visit_assignment thinks that the range for
3953 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3954 is not visited again, which stops propagation from visiting
3955 statements in the THEN clause of that if().
3957 To properly fix this we would need to keep the previous range
3958 value for the names in the equivalence set. This way we would've
3959 discovered that from one visit to the other i_5 changed from
3960 range [8, 8] to VR_VARYING.
3962 However, fixing this apparent limitation may not be worth the
3963 additional checking. Testing on several code bases (GCC, DLV,
3964 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3965 4 more predicates folded in SPEC. */
3966 val
= vrp_evaluate_conditional (cond
, false);
3968 *taken_edge_p
= find_taken_edge (bb_for_stmt (stmt
), val
);
3970 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3972 fprintf (dump_file
, "\nPredicate evaluates to: ");
3973 if (val
== NULL_TREE
)
3974 fprintf (dump_file
, "DON'T KNOW\n");
3976 print_generic_stmt (dump_file
, val
, 0);
3979 return (*taken_edge_p
) ? SSA_PROP_INTERESTING
: SSA_PROP_VARYING
;
3983 /* Evaluate statement STMT. If the statement produces a useful range,
3984 return SSA_PROP_INTERESTING and record the SSA name with the
3985 interesting range into *OUTPUT_P.
3987 If STMT is a conditional branch and we can determine its truth
3988 value, the taken edge is recorded in *TAKEN_EDGE_P.
3990 If STMT produces a varying value, return SSA_PROP_VARYING. */
3992 static enum ssa_prop_result
3993 vrp_visit_stmt (tree stmt
, edge
*taken_edge_p
, tree
*output_p
)
3999 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4001 fprintf (dump_file
, "\nVisiting statement:\n");
4002 print_generic_stmt (dump_file
, stmt
, dump_flags
);
4003 fprintf (dump_file
, "\n");
4006 ann
= stmt_ann (stmt
);
4007 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
4009 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
4011 /* In general, assignments with virtual operands are not useful
4012 for deriving ranges, with the obvious exception of calls to
4013 builtin functions. */
4014 if ((TREE_CODE (rhs
) == CALL_EXPR
4015 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == ADDR_EXPR
4016 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0))
4017 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0)))
4018 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
4019 return vrp_visit_assignment (stmt
, output_p
);
4021 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
4022 return vrp_visit_cond_stmt (stmt
, taken_edge_p
);
4024 /* All other statements produce nothing of interest for VRP, so mark
4025 their outputs varying and prevent further simulation. */
4026 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
4027 set_value_range_to_varying (get_value_range (def
));
4029 return SSA_PROP_VARYING
;
4033 /* Meet operation for value ranges. Given two value ranges VR0 and
4034 VR1, store in VR0 a range that contains both VR0 and VR1. This
4035 may not be the smallest possible such range. */
4038 vrp_meet (value_range_t
*vr0
, value_range_t
*vr1
)
4040 if (vr0
->type
== VR_UNDEFINED
)
4042 copy_value_range (vr0
, vr1
);
4046 if (vr1
->type
== VR_UNDEFINED
)
4048 /* Nothing to do. VR0 already has the resulting range. */
4052 if (vr0
->type
== VR_VARYING
)
4054 /* Nothing to do. VR0 already has the resulting range. */
4058 if (vr1
->type
== VR_VARYING
)
4060 set_value_range_to_varying (vr0
);
4064 if (vr0
->type
== VR_RANGE
&& vr1
->type
== VR_RANGE
)
4069 /* Compute the convex hull of the ranges. The lower limit of
4070 the new range is the minimum of the two ranges. If they
4071 cannot be compared, then give up. */
4072 cmp
= compare_values (vr0
->min
, vr1
->min
);
4073 if (cmp
== 0 || cmp
== 1)
4080 /* Similarly, the upper limit of the new range is the maximum
4081 of the two ranges. If they cannot be compared, then
4083 cmp
= compare_values (vr0
->max
, vr1
->max
);
4084 if (cmp
== 0 || cmp
== -1)
4091 /* The resulting set of equivalences is the intersection of
4093 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
4094 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
4095 else if (vr0
->equiv
&& !vr1
->equiv
)
4096 bitmap_clear (vr0
->equiv
);
4098 set_value_range (vr0
, vr0
->type
, min
, max
, vr0
->equiv
);
4100 else if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
4102 /* Two anti-ranges meet only if their complements intersect.
4103 Only handle the case of identical ranges. */
4104 if (compare_values (vr0
->min
, vr1
->min
) == 0
4105 && compare_values (vr0
->max
, vr1
->max
) == 0
4106 && compare_values (vr0
->min
, vr0
->max
) == 0)
4108 /* The resulting set of equivalences is the intersection of
4110 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
4111 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
4112 else if (vr0
->equiv
&& !vr1
->equiv
)
4113 bitmap_clear (vr0
->equiv
);
4118 else if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
4120 /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4],
4121 only handle the case where the ranges have an empty intersection.
4122 The result of the meet operation is the anti-range. */
4123 if (!symbolic_range_p (vr0
)
4124 && !symbolic_range_p (vr1
)
4125 && !value_ranges_intersect_p (vr0
, vr1
))
4127 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
4128 set. We need to compute the intersection of the two
4129 equivalence sets. */
4130 if (vr1
->type
== VR_ANTI_RANGE
)
4131 set_value_range (vr0
, vr1
->type
, vr1
->min
, vr1
->max
, vr0
->equiv
);
4133 /* The resulting set of equivalences is the intersection of
4135 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
4136 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
4137 else if (vr0
->equiv
&& !vr1
->equiv
)
4138 bitmap_clear (vr0
->equiv
);
4149 /* Failed to find an efficient meet. Before giving up and setting
4150 the result to VARYING, see if we can at least derive a useful
4151 anti-range. FIXME, all this nonsense about distinguishing
4152 anti-ranges from ranges is necessary because of the odd
4153 semantics of range_includes_zero_p and friends. */
4154 if (!symbolic_range_p (vr0
)
4155 && ((vr0
->type
== VR_RANGE
&& !range_includes_zero_p (vr0
))
4156 || (vr0
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr0
)))
4157 && !symbolic_range_p (vr1
)
4158 && ((vr1
->type
== VR_RANGE
&& !range_includes_zero_p (vr1
))
4159 || (vr1
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr1
))))
4161 set_value_range_to_nonnull (vr0
, TREE_TYPE (vr0
->min
));
4163 /* Since this meet operation did not result from the meeting of
4164 two equivalent names, VR0 cannot have any equivalences. */
4166 bitmap_clear (vr0
->equiv
);
4169 set_value_range_to_varying (vr0
);
4173 /* Visit all arguments for PHI node PHI that flow through executable
4174 edges. If a valid value range can be derived from all the incoming
4175 value ranges, set a new range for the LHS of PHI. */
4177 static enum ssa_prop_result
4178 vrp_visit_phi_node (tree phi
)
4181 tree lhs
= PHI_RESULT (phi
);
4182 value_range_t
*lhs_vr
= get_value_range (lhs
);
4183 value_range_t vr_result
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
4185 copy_value_range (&vr_result
, lhs_vr
);
4187 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4189 fprintf (dump_file
, "\nVisiting PHI node: ");
4190 print_generic_expr (dump_file
, phi
, dump_flags
);
4193 for (i
= 0; i
< PHI_NUM_ARGS (phi
); i
++)
4195 edge e
= PHI_ARG_EDGE (phi
, i
);
4197 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4200 "\n Argument #%d (%d -> %d %sexecutable)\n",
4201 i
, e
->src
->index
, e
->dest
->index
,
4202 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
4205 if (e
->flags
& EDGE_EXECUTABLE
)
4207 tree arg
= PHI_ARG_DEF (phi
, i
);
4208 value_range_t vr_arg
;
4210 if (TREE_CODE (arg
) == SSA_NAME
)
4211 vr_arg
= *(get_value_range (arg
));
4214 vr_arg
.type
= VR_RANGE
;
4217 vr_arg
.equiv
= NULL
;
4220 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4222 fprintf (dump_file
, "\t");
4223 print_generic_expr (dump_file
, arg
, dump_flags
);
4224 fprintf (dump_file
, "\n\tValue: ");
4225 dump_value_range (dump_file
, &vr_arg
);
4226 fprintf (dump_file
, "\n");
4229 vrp_meet (&vr_result
, &vr_arg
);
4231 if (vr_result
.type
== VR_VARYING
)
4236 if (vr_result
.type
== VR_VARYING
)
4239 /* To prevent infinite iterations in the algorithm, derive ranges
4240 when the new value is slightly bigger or smaller than the
4242 if (lhs_vr
->type
== VR_RANGE
&& vr_result
.type
== VR_RANGE
)
4244 if (!POINTER_TYPE_P (TREE_TYPE (lhs
)))
4246 int cmp_min
= compare_values (lhs_vr
->min
, vr_result
.min
);
4247 int cmp_max
= compare_values (lhs_vr
->max
, vr_result
.max
);
4249 /* If the new minimum is smaller or larger than the previous
4250 one, go all the way to -INF. In the first case, to avoid
4251 iterating millions of times to reach -INF, and in the
4252 other case to avoid infinite bouncing between different
4254 if (cmp_min
> 0 || cmp_min
< 0)
4255 vr_result
.min
= TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
));
4257 /* Similarly, if the new maximum is smaller or larger than
4258 the previous one, go all the way to +INF. */
4259 if (cmp_max
< 0 || cmp_max
> 0)
4260 vr_result
.max
= TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
));
4262 /* If we ended up with a (-INF, +INF) range, set it to
4264 if (vr_result
.min
== TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
))
4265 && vr_result
.max
== TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
)))
4270 /* If the new range is different than the previous value, keep
4272 if (update_value_range (lhs
, &vr_result
))
4273 return SSA_PROP_INTERESTING
;
4275 /* Nothing changed, don't add outgoing edges. */
4276 return SSA_PROP_NOT_INTERESTING
;
4278 /* No match found. Set the LHS to VARYING. */
4280 set_value_range_to_varying (lhs_vr
);
4281 return SSA_PROP_VARYING
;
4284 /* Simplify a division or modulo operator to a right shift or
4285 bitwise and if the first operand is unsigned or is greater
4286 than zero and the second operand is an exact power of two. */
4289 simplify_div_or_mod_using_ranges (tree stmt
, tree rhs
, enum tree_code rhs_code
)
4292 tree op
= TREE_OPERAND (rhs
, 0);
4293 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
4295 if (TYPE_UNSIGNED (TREE_TYPE (op
)))
4297 val
= integer_one_node
;
4301 val
= compare_range_with_value (GT_EXPR
, vr
, integer_zero_node
);
4304 if (val
&& integer_onep (val
))
4307 tree op0
= TREE_OPERAND (rhs
, 0);
4308 tree op1
= TREE_OPERAND (rhs
, 1);
4310 if (rhs_code
== TRUNC_DIV_EXPR
)
4312 t
= build_int_cst (NULL_TREE
, tree_log2 (op1
));
4313 t
= build2 (RSHIFT_EXPR
, TREE_TYPE (op0
), op0
, t
);
4317 t
= build_int_cst (TREE_TYPE (op1
), 1);
4318 t
= int_const_binop (MINUS_EXPR
, op1
, t
, 0);
4319 t
= fold_convert (TREE_TYPE (op0
), t
);
4320 t
= build2 (BIT_AND_EXPR
, TREE_TYPE (op0
), op0
, t
);
4323 GIMPLE_STMT_OPERAND (stmt
, 1) = t
;
4328 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
4329 ABS_EXPR. If the operand is <= 0, then simplify the
4330 ABS_EXPR into a NEGATE_EXPR. */
4333 simplify_abs_using_ranges (tree stmt
, tree rhs
)
4336 tree op
= TREE_OPERAND (rhs
, 0);
4337 tree type
= TREE_TYPE (op
);
4338 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
4340 if (TYPE_UNSIGNED (type
))
4342 val
= integer_zero_node
;
4346 val
= compare_range_with_value (LE_EXPR
, vr
, integer_zero_node
);
4349 val
= compare_range_with_value (GE_EXPR
, vr
, integer_zero_node
);
4353 if (integer_zerop (val
))
4354 val
= integer_one_node
;
4355 else if (integer_onep (val
))
4356 val
= integer_zero_node
;
4361 && (integer_onep (val
) || integer_zerop (val
)))
4365 if (integer_onep (val
))
4366 t
= build1 (NEGATE_EXPR
, TREE_TYPE (op
), op
);
4370 GIMPLE_STMT_OPERAND (stmt
, 1) = t
;
4376 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
4377 a known value range VR.
4379 If there is one and only one value which will satisfy the
4380 conditional, then return that value. Else return NULL. */
4383 test_for_singularity (enum tree_code cond_code
, tree op0
,
4384 tree op1
, value_range_t
*vr
)
4389 /* Extract minimum/maximum values which satisfy the
4390 the conditional as it was written. */
4391 if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
4393 min
= TYPE_MIN_VALUE (TREE_TYPE (op0
));
4396 if (cond_code
== LT_EXPR
)
4398 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
4399 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (op0
), max
, one
);
4402 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
4404 max
= TYPE_MAX_VALUE (TREE_TYPE (op0
));
4407 if (cond_code
== GT_EXPR
)
4409 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
4410 min
= fold_build2 (PLUS_EXPR
, TREE_TYPE (op0
), min
, one
);
4414 /* Now refine the minimum and maximum values using any
4415 value range information we have for op0. */
4418 if (compare_values (vr
->min
, min
) == -1)
4422 if (compare_values (vr
->max
, max
) == 1)
4427 /* If the new min/max values have converged to a single value,
4428 then there is only one value which can satisfy the condition,
4429 return that value. */
4430 if (operand_equal_p (min
, max
, 0) && is_gimple_min_invariant (min
))
4436 /* Simplify a conditional using a relational operator to an equality
4437 test if the range information indicates only one value can satisfy
4438 the original conditional. */
4441 simplify_cond_using_ranges (tree stmt
)
4443 tree cond
= COND_EXPR_COND (stmt
);
4444 tree op0
= TREE_OPERAND (cond
, 0);
4445 tree op1
= TREE_OPERAND (cond
, 1);
4446 enum tree_code cond_code
= TREE_CODE (cond
);
4448 if (cond_code
!= NE_EXPR
4449 && cond_code
!= EQ_EXPR
4450 && TREE_CODE (op0
) == SSA_NAME
4451 && INTEGRAL_TYPE_P (TREE_TYPE (op0
))
4452 && is_gimple_min_invariant (op1
))
4454 value_range_t
*vr
= get_value_range (op0
);
4456 /* If we have range information for OP0, then we might be
4457 able to simplify this conditional. */
4458 if (vr
->type
== VR_RANGE
)
4460 tree
new = test_for_singularity (cond_code
, op0
, op1
, vr
);
4466 fprintf (dump_file
, "Simplified relational ");
4467 print_generic_expr (dump_file
, cond
, 0);
4468 fprintf (dump_file
, " into ");
4471 COND_EXPR_COND (stmt
)
4472 = build2 (EQ_EXPR
, boolean_type_node
, op0
, new);
4477 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
4478 fprintf (dump_file
, "\n");
4484 /* Try again after inverting the condition. We only deal
4485 with integral types here, so no need to worry about
4486 issues with inverting FP comparisons. */
4487 cond_code
= invert_tree_comparison (cond_code
, false);
4488 new = test_for_singularity (cond_code
, op0
, op1
, vr
);
4494 fprintf (dump_file
, "Simplified relational ");
4495 print_generic_expr (dump_file
, cond
, 0);
4496 fprintf (dump_file
, " into ");
4499 COND_EXPR_COND (stmt
)
4500 = build2 (NE_EXPR
, boolean_type_node
, op0
, new);
4505 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
4506 fprintf (dump_file
, "\n");
4515 /* Simplify STMT using ranges if possible. */
4518 simplify_stmt_using_ranges (tree stmt
)
4520 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
4522 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
4523 enum tree_code rhs_code
= TREE_CODE (rhs
);
4525 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
4526 and BIT_AND_EXPR respectively if the first operand is greater
4527 than zero and the second operand is an exact power of two. */
4528 if ((rhs_code
== TRUNC_DIV_EXPR
|| rhs_code
== TRUNC_MOD_EXPR
)
4529 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0)))
4530 && integer_pow2p (TREE_OPERAND (rhs
, 1)))
4531 simplify_div_or_mod_using_ranges (stmt
, rhs
, rhs_code
);
4533 /* Transform ABS (X) into X or -X as appropriate. */
4534 if (rhs_code
== ABS_EXPR
4535 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == SSA_NAME
4536 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0))))
4537 simplify_abs_using_ranges (stmt
, rhs
);
4539 else if (TREE_CODE (stmt
) == COND_EXPR
4540 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt
)))
4542 simplify_cond_using_ranges (stmt
);
4546 /* Stack of dest,src equivalency pairs that need to be restored after
4547 each attempt to thread a block's incoming edge to an outgoing edge.
4549 A NULL entry is used to mark the end of pairs which need to be
4551 static VEC(tree
,heap
) *stack
;
4553 /* A trivial wrapper so that we can present the generic jump
4554 threading code with a simple API for simplifying statements. */
4556 simplify_stmt_for_jump_threading (tree stmt
)
4558 /* We only use VRP information to simplify conditionals. This is
4559 overly conservative, but it's unclear if doing more would be
4560 worth the compile time cost. */
4561 if (TREE_CODE (stmt
) != COND_EXPR
)
4564 return vrp_evaluate_conditional (COND_EXPR_COND (stmt
), true);
4567 /* Blocks which have more than one predecessor and more than
4568 one successor present jump threading opportunities. ie,
4569 when the block is reached from a specific predecessor, we
4570 may be able to determine which of the outgoing edges will
4571 be traversed. When this optimization applies, we are able
4572 to avoid conditionals at runtime and we may expose secondary
4573 optimization opportunities.
4575 This routine is effectively a driver for the generic jump
4576 threading code. It basically just presents the generic code
4577 with edges that may be suitable for jump threading.
4579 Unlike DOM, we do not iterate VRP if jump threading was successful.
4580 While iterating may expose new opportunities for VRP, it is expected
4581 those opportunities would be very limited and the compile time cost
4582 to expose those opportunities would be significant.
4584 As jump threading opportunities are discovered, they are registered
4585 for later realization. */
4588 identify_jump_threads (void)
4593 /* Ugh. When substituting values earlier in this pass we can
4594 wipe the dominance information. So rebuild the dominator
4595 information as we need it within the jump threading code. */
4596 calculate_dominance_info (CDI_DOMINATORS
);
4598 /* We do not allow VRP information to be used for jump threading
4599 across a back edge in the CFG. Otherwise it becomes too
4600 difficult to avoid eliminating loop exit tests. Of course
4601 EDGE_DFS_BACK is not accurate at this time so we have to
4603 mark_dfs_back_edges ();
4605 /* Allocate our unwinder stack to unwind any temporary equivalences
4606 that might be recorded. */
4607 stack
= VEC_alloc (tree
, heap
, 20);
4609 /* To avoid lots of silly node creation, we create a single
4610 conditional and just modify it in-place when attempting to
4612 dummy
= build2 (EQ_EXPR
, boolean_type_node
, NULL
, NULL
);
4613 dummy
= build3 (COND_EXPR
, void_type_node
, dummy
, NULL
, NULL
);
4615 /* Walk through all the blocks finding those which present a
4616 potential jump threading opportunity. We could set this up
4617 as a dominator walker and record data during the walk, but
4618 I doubt it's worth the effort for the classes of jump
4619 threading opportunities we are trying to identify at this
4620 point in compilation. */
4625 /* If the generic jump threading code does not find this block
4626 interesting, then there is nothing to do. */
4627 if (! potentially_threadable_block (bb
))
4630 /* We only care about blocks ending in a COND_EXPR. While there
4631 may be some value in handling SWITCH_EXPR here, I doubt it's
4632 terribly important. */
4633 last
= bsi_stmt (bsi_last (bb
));
4634 if (TREE_CODE (last
) != COND_EXPR
)
4637 /* We're basically looking for any kind of conditional with
4638 integral type arguments. */
4639 cond
= COND_EXPR_COND (last
);
4640 if ((TREE_CODE (cond
) == SSA_NAME
4641 && INTEGRAL_TYPE_P (TREE_TYPE (cond
)))
4642 || (COMPARISON_CLASS_P (cond
)
4643 && TREE_CODE (TREE_OPERAND (cond
, 0)) == SSA_NAME
4644 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond
, 0)))
4645 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == SSA_NAME
4646 || is_gimple_min_invariant (TREE_OPERAND (cond
, 1)))
4647 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond
, 1)))))
4652 /* We've got a block with multiple predecessors and multiple
4653 successors which also ends in a suitable conditional. For
4654 each predecessor, see if we can thread it to a specific
4656 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4658 /* Do not thread across back edges or abnormal edges
4660 if (e
->flags
& (EDGE_DFS_BACK
| EDGE_COMPLEX
))
4663 thread_across_edge (dummy
, e
, true,
4665 simplify_stmt_for_jump_threading
);
4670 /* We do not actually update the CFG or SSA graphs at this point as
4671 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
4672 handle ASSERT_EXPRs gracefully. */
4675 /* We identified all the jump threading opportunities earlier, but could
4676 not transform the CFG at that time. This routine transforms the
4677 CFG and arranges for the dominator tree to be rebuilt if necessary.
4679 Note the SSA graph update will occur during the normal TODO
4680 processing by the pass manager. */
4682 finalize_jump_threads (void)
4684 bool cfg_altered
= false;
4685 cfg_altered
= thread_through_all_blocks ();
4687 /* If we threaded jumps, then we need to recompute the dominance
4688 information, to safely do that we must clean up the CFG first. */
4691 free_dominance_info (CDI_DOMINATORS
);
4692 cleanup_tree_cfg ();
4693 calculate_dominance_info (CDI_DOMINATORS
);
4695 VEC_free (tree
, heap
, stack
);
4699 /* Traverse all the blocks folding conditionals with known ranges. */
4705 prop_value_t
*single_val_range
;
4706 bool do_value_subst_p
;
4710 fprintf (dump_file
, "\nValue ranges after VRP:\n\n");
4711 dump_all_value_ranges (dump_file
);
4712 fprintf (dump_file
, "\n");
4715 /* We may have ended with ranges that have exactly one value. Those
4716 values can be substituted as any other copy/const propagated
4717 value using substitute_and_fold. */
4718 single_val_range
= XCNEWVEC (prop_value_t
, num_ssa_names
);
4720 do_value_subst_p
= false;
4721 for (i
= 0; i
< num_ssa_names
; i
++)
4723 && vr_value
[i
]->type
== VR_RANGE
4724 && vr_value
[i
]->min
== vr_value
[i
]->max
)
4726 single_val_range
[i
].value
= vr_value
[i
]->min
;
4727 do_value_subst_p
= true;
4730 if (!do_value_subst_p
)
4732 /* We found no single-valued ranges, don't waste time trying to
4733 do single value substitution in substitute_and_fold. */
4734 free (single_val_range
);
4735 single_val_range
= NULL
;
4738 substitute_and_fold (single_val_range
, true);
4740 /* We must identify jump threading opportunities before we release
4741 the datastructures built by VRP. */
4742 identify_jump_threads ();
4744 /* Free allocated memory. */
4745 for (i
= 0; i
< num_ssa_names
; i
++)
4748 BITMAP_FREE (vr_value
[i
]->equiv
);
4752 free (single_val_range
);
4755 /* So that we can distinguish between VRP data being available
4756 and not available. */
4761 /* Main entry point to VRP (Value Range Propagation). This pass is
4762 loosely based on J. R. C. Patterson, ``Accurate Static Branch
4763 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
4764 Programming Language Design and Implementation, pp. 67-78, 1995.
4765 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
4767 This is essentially an SSA-CCP pass modified to deal with ranges
4768 instead of constants.
4770 While propagating ranges, we may find that two or more SSA name
4771 have equivalent, though distinct ranges. For instance,
4774 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
4776 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
4780 In the code above, pointer p_5 has range [q_2, q_2], but from the
4781 code we can also determine that p_5 cannot be NULL and, if q_2 had
4782 a non-varying range, p_5's range should also be compatible with it.
4784 These equivalences are created by two expressions: ASSERT_EXPR and
4785 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
4786 result of another assertion, then we can use the fact that p_5 and
4787 p_4 are equivalent when evaluating p_5's range.
4789 Together with value ranges, we also propagate these equivalences
4790 between names so that we can take advantage of information from
4791 multiple ranges when doing final replacement. Note that this
4792 equivalency relation is transitive but not symmetric.
4794 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
4795 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
4796 in contexts where that assertion does not hold (e.g., in line 6).
4798 TODO, the main difference between this pass and Patterson's is that
4799 we do not propagate edge probabilities. We only compute whether
4800 edges can be taken or not. That is, instead of having a spectrum
4801 of jump probabilities between 0 and 1, we only deal with 0, 1 and
4802 DON'T KNOW. In the future, it may be worthwhile to propagate
4803 probabilities to aid branch prediction. */
4808 insert_range_assertions ();
4810 loop_optimizer_init (LOOPS_NORMAL
);
4815 ssa_propagate (vrp_visit_stmt
, vrp_visit_phi_node
);
4821 loop_optimizer_finalize ();
4824 /* ASSERT_EXPRs must be removed before finalizing jump threads
4825 as finalizing jump threads calls the CFG cleanup code which
4826 does not properly handle ASSERT_EXPRs. */
4827 remove_range_assertions ();
4829 /* If we exposed any new variables, go ahead and put them into
4830 SSA form now, before we handle jump threading. This simplifies
4831 interactions between rewriting of _DECL nodes into SSA form
4832 and rewriting SSA_NAME nodes into SSA form after block
4833 duplication and CFG manipulation. */
4834 update_ssa (TODO_update_ssa
);
4836 finalize_jump_threads ();
4843 return flag_tree_vrp
!= 0;
4846 struct tree_opt_pass pass_vrp
=
4849 gate_vrp
, /* gate */
4850 execute_vrp
, /* execute */
4853 0, /* static_pass_number */
4854 TV_TREE_VRP
, /* tv_id */
4855 PROP_ssa
| PROP_alias
, /* properties_required */
4856 0, /* properties_provided */
4857 0, /* properties_destroyed */
4858 0, /* todo_flags_start */
4864 | TODO_update_smt_usage
, /* todo_flags_finish */