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 /* Loop structure of the program. Used to analyze scalar evolutions
45 inside adjust_range_with_scev. */
46 static struct loops
*cfg_loops
;
48 /* Local functions. */
49 static int compare_values (tree val1
, tree val2
);
51 /* Location information for ASSERT_EXPRs. Each instance of this
52 structure describes an ASSERT_EXPR for an SSA name. Since a single
53 SSA name may have more than one assertion associated with it, these
54 locations are kept in a linked list attached to the corresponding
58 /* Basic block where the assertion would be inserted. */
61 /* Some assertions need to be inserted on an edge (e.g., assertions
62 generated by COND_EXPRs). In those cases, BB will be NULL. */
65 /* Pointer to the statement that generated this assertion. */
66 block_stmt_iterator si
;
68 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
69 enum tree_code comp_code
;
71 /* Value being compared against. */
74 /* Next node in the linked list. */
75 struct assert_locus_d
*next
;
78 typedef struct assert_locus_d
*assert_locus_t
;
80 /* If bit I is present, it means that SSA name N_i has a list of
81 assertions that should be inserted in the IL. */
82 static bitmap need_assert_for
;
84 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
85 holds a list of ASSERT_LOCUS_T nodes that describe where
86 ASSERT_EXPRs for SSA name N_I should be inserted. */
87 static assert_locus_t
*asserts_for
;
89 /* Set of blocks visited in find_assert_locations. Used to avoid
90 visiting the same block more than once. */
91 static sbitmap blocks_visited
;
93 /* Value range array. After propagation, VR_VALUE[I] holds the range
94 of values that SSA name N_I may take. */
95 static value_range_t
**vr_value
;
98 /* Return true if ARG is marked with the nonnull attribute in the
99 current function signature. */
102 nonnull_arg_p (tree arg
)
104 tree t
, attrs
, fntype
;
105 unsigned HOST_WIDE_INT arg_num
;
107 gcc_assert (TREE_CODE (arg
) == PARM_DECL
&& POINTER_TYPE_P (TREE_TYPE (arg
)));
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
);
199 /* Set value range VR to a non-NULL range of type TYPE. */
202 set_value_range_to_nonnull (value_range_t
*vr
, tree type
)
204 tree zero
= build_int_cst (type
, 0);
205 set_value_range (vr
, VR_ANTI_RANGE
, zero
, zero
, vr
->equiv
);
209 /* Set value range VR to a NULL range of type TYPE. */
212 set_value_range_to_null (value_range_t
*vr
, tree type
)
214 tree zero
= build_int_cst (type
, 0);
215 set_value_range (vr
, VR_RANGE
, zero
, zero
, vr
->equiv
);
219 /* Set value range VR to VR_VARYING. */
222 set_value_range_to_varying (value_range_t
*vr
)
224 vr
->type
= VR_VARYING
;
225 vr
->min
= vr
->max
= NULL_TREE
;
227 bitmap_clear (vr
->equiv
);
231 /* Set value range VR to VR_UNDEFINED. */
234 set_value_range_to_undefined (value_range_t
*vr
)
236 vr
->type
= VR_UNDEFINED
;
237 vr
->min
= vr
->max
= NULL_TREE
;
239 bitmap_clear (vr
->equiv
);
243 /* Return value range information for VAR. Create an empty range
246 static value_range_t
*
247 get_value_range (tree var
)
251 unsigned ver
= SSA_NAME_VERSION (var
);
257 /* Create a default value range. */
258 vr_value
[ver
] = vr
= XNEW (value_range_t
);
259 memset (vr
, 0, sizeof (*vr
));
261 /* Allocate an equivalence set. */
262 vr
->equiv
= BITMAP_ALLOC (NULL
);
264 /* If VAR is a default definition, the variable can take any value
266 sym
= SSA_NAME_VAR (var
);
267 if (var
== default_def (sym
))
269 /* Try to use the "nonnull" attribute to create ~[0, 0]
270 anti-ranges for pointers. Note that this is only valid with
271 default definitions of PARM_DECLs. */
272 if (TREE_CODE (sym
) == PARM_DECL
273 && POINTER_TYPE_P (TREE_TYPE (sym
))
274 && nonnull_arg_p (sym
))
275 set_value_range_to_nonnull (vr
, TREE_TYPE (sym
));
277 set_value_range_to_varying (vr
);
284 /* Update the value range and equivalence set for variable VAR to
285 NEW_VR. Return true if NEW_VR is different from VAR's previous
288 NOTE: This function assumes that NEW_VR is a temporary value range
289 object created for the sole purpose of updating VAR's range. The
290 storage used by the equivalence set from NEW_VR will be freed by
291 this function. Do not call update_value_range when NEW_VR
292 is the range object associated with another SSA name. */
295 update_value_range (tree var
, value_range_t
*new_vr
)
297 value_range_t
*old_vr
;
300 /* Update the value range, if necessary. */
301 old_vr
= get_value_range (var
);
302 is_new
= old_vr
->type
!= new_vr
->type
303 || old_vr
->min
!= new_vr
->min
304 || old_vr
->max
!= new_vr
->max
305 || (old_vr
->equiv
== NULL
&& new_vr
->equiv
)
306 || (old_vr
->equiv
&& new_vr
->equiv
== NULL
)
307 || (!bitmap_equal_p (old_vr
->equiv
, new_vr
->equiv
));
310 set_value_range (old_vr
, new_vr
->type
, new_vr
->min
, new_vr
->max
,
313 BITMAP_FREE (new_vr
->equiv
);
314 new_vr
->equiv
= NULL
;
320 /* Add VAR and VAR's equivalence set to EQUIV. */
323 add_equivalence (bitmap equiv
, tree var
)
325 unsigned ver
= SSA_NAME_VERSION (var
);
326 value_range_t
*vr
= vr_value
[ver
];
328 bitmap_set_bit (equiv
, ver
);
330 bitmap_ior_into (equiv
, vr
->equiv
);
334 /* Return true if VR is ~[0, 0]. */
337 range_is_nonnull (value_range_t
*vr
)
339 return vr
->type
== VR_ANTI_RANGE
340 && integer_zerop (vr
->min
)
341 && integer_zerop (vr
->max
);
345 /* Return true if VR is [0, 0]. */
348 range_is_null (value_range_t
*vr
)
350 return vr
->type
== VR_RANGE
351 && integer_zerop (vr
->min
)
352 && integer_zerop (vr
->max
);
356 /* Return true if value range VR involves at least one symbol. */
359 symbolic_range_p (value_range_t
*vr
)
361 return (!is_gimple_min_invariant (vr
->min
)
362 || !is_gimple_min_invariant (vr
->max
));
366 /* Like tree_expr_nonzero_p, but this function uses value ranges
370 vrp_expr_computes_nonzero (tree expr
)
372 if (tree_expr_nonzero_p (expr
))
375 /* If we have an expression of the form &X->a, then the expression
376 is nonnull if X is nonnull. */
377 if (TREE_CODE (expr
) == ADDR_EXPR
)
379 tree base
= get_base_address (TREE_OPERAND (expr
, 0));
381 if (base
!= NULL_TREE
382 && TREE_CODE (base
) == INDIRECT_REF
383 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
385 value_range_t
*vr
= get_value_range (TREE_OPERAND (base
, 0));
386 if (range_is_nonnull (vr
))
395 /* Compare two values VAL1 and VAL2. Return
397 -2 if VAL1 and VAL2 cannot be compared at compile-time,
400 +1 if VAL1 > VAL2, and
403 This is similar to tree_int_cst_compare but supports pointer values
404 and values that cannot be compared at compile time. */
407 compare_values (tree val1
, tree val2
)
412 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
414 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1
))
415 == POINTER_TYPE_P (TREE_TYPE (val2
)));
417 /* Do some limited symbolic comparisons. */
418 if (!POINTER_TYPE_P (TREE_TYPE (val1
)))
420 /* We can determine some comparisons against +INF and -INF even
421 if the other value is an expression. */
422 if (val1
== TYPE_MAX_VALUE (TREE_TYPE (val1
))
423 && TREE_CODE (val2
) == MINUS_EXPR
)
425 /* +INF > NAME - CST. */
428 else if (val1
== TYPE_MIN_VALUE (TREE_TYPE (val1
))
429 && TREE_CODE (val2
) == PLUS_EXPR
)
431 /* -INF < NAME + CST. */
434 else if (TREE_CODE (val1
) == MINUS_EXPR
435 && val2
== TYPE_MAX_VALUE (TREE_TYPE (val2
)))
437 /* NAME - CST < +INF. */
440 else if (TREE_CODE (val1
) == PLUS_EXPR
441 && val2
== TYPE_MIN_VALUE (TREE_TYPE (val2
)))
443 /* NAME + CST > -INF. */
448 if ((TREE_CODE (val1
) == SSA_NAME
449 || TREE_CODE (val1
) == PLUS_EXPR
450 || TREE_CODE (val1
) == MINUS_EXPR
)
451 && (TREE_CODE (val2
) == SSA_NAME
452 || TREE_CODE (val2
) == PLUS_EXPR
453 || TREE_CODE (val2
) == MINUS_EXPR
))
457 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
458 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
459 same name, return -2. */
460 if (TREE_CODE (val1
) == SSA_NAME
)
467 n1
= TREE_OPERAND (val1
, 0);
468 c1
= TREE_OPERAND (val1
, 1);
471 if (TREE_CODE (val2
) == SSA_NAME
)
478 n2
= TREE_OPERAND (val2
, 0);
479 c2
= TREE_OPERAND (val2
, 1);
482 /* Both values must use the same name. */
486 if (TREE_CODE (val1
) == SSA_NAME
)
488 if (TREE_CODE (val2
) == SSA_NAME
)
491 else if (TREE_CODE (val2
) == PLUS_EXPR
)
492 /* NAME < NAME + CST */
494 else if (TREE_CODE (val2
) == MINUS_EXPR
)
495 /* NAME > NAME - CST */
498 else if (TREE_CODE (val1
) == PLUS_EXPR
)
500 if (TREE_CODE (val2
) == SSA_NAME
)
501 /* NAME + CST > NAME */
503 else if (TREE_CODE (val2
) == PLUS_EXPR
)
504 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
505 return compare_values (c1
, c2
);
506 else if (TREE_CODE (val2
) == MINUS_EXPR
)
507 /* NAME + CST1 > NAME - CST2 */
510 else if (TREE_CODE (val1
) == MINUS_EXPR
)
512 if (TREE_CODE (val2
) == SSA_NAME
)
513 /* NAME - CST < NAME */
515 else if (TREE_CODE (val2
) == PLUS_EXPR
)
516 /* NAME - CST1 < NAME + CST2 */
518 else if (TREE_CODE (val2
) == MINUS_EXPR
)
519 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
520 C1 and C2 are swapped in the call to compare_values. */
521 return compare_values (c2
, c1
);
527 /* We cannot compare non-constants. */
528 if (!is_gimple_min_invariant (val1
) || !is_gimple_min_invariant (val2
))
531 if (!POINTER_TYPE_P (TREE_TYPE (val1
)))
533 /* We cannot compare overflowed values. */
534 if (TREE_OVERFLOW (val1
) || TREE_OVERFLOW (val2
))
537 return tree_int_cst_compare (val1
, val2
);
543 /* First see if VAL1 and VAL2 are not the same. */
544 if (val1
== val2
|| operand_equal_p (val1
, val2
, 0))
547 /* If VAL1 is a lower address than VAL2, return -1. */
548 t
= fold_binary (LT_EXPR
, boolean_type_node
, val1
, val2
);
549 if (t
== boolean_true_node
)
552 /* If VAL1 is a higher address than VAL2, return +1. */
553 t
= fold_binary (GT_EXPR
, boolean_type_node
, val1
, val2
);
554 if (t
== boolean_true_node
)
557 /* If VAL1 is different than VAL2, return +2. */
558 t
= fold_binary (NE_EXPR
, boolean_type_node
, val1
, val2
);
559 if (t
== boolean_true_node
)
567 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
568 0 if VAL is not inside VR,
569 -2 if we cannot tell either way.
571 FIXME, the current semantics of this functions are a bit quirky
572 when taken in the context of VRP. In here we do not care
573 about VR's type. If VR is the anti-range ~[3, 5] the call
574 value_inside_range (4, VR) will return 1.
576 This is counter-intuitive in a strict sense, but the callers
577 currently expect this. They are calling the function
578 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
579 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
582 This also applies to value_ranges_intersect_p and
583 range_includes_zero_p. The semantics of VR_RANGE and
584 VR_ANTI_RANGE should be encoded here, but that also means
585 adapting the users of these functions to the new semantics. */
588 value_inside_range (tree val
, value_range_t
*vr
)
592 cmp1
= compare_values (val
, vr
->min
);
593 if (cmp1
== -2 || cmp1
== 2)
596 cmp2
= compare_values (val
, vr
->max
);
597 if (cmp2
== -2 || cmp2
== 2)
600 return (cmp1
== 0 || cmp1
== 1) && (cmp2
== -1 || cmp2
== 0);
604 /* Return true if value ranges VR0 and VR1 have a non-empty
608 value_ranges_intersect_p (value_range_t
*vr0
, value_range_t
*vr1
)
610 return (value_inside_range (vr1
->min
, vr0
) == 1
611 || value_inside_range (vr1
->max
, vr0
) == 1
612 || value_inside_range (vr0
->min
, vr1
) == 1
613 || value_inside_range (vr0
->max
, vr1
) == 1);
617 /* Return true if VR includes the value zero, false otherwise. FIXME,
618 currently this will return false for an anti-range like ~[-4, 3].
619 This will be wrong when the semantics of value_inside_range are
620 modified (currently the users of this function expect these
624 range_includes_zero_p (value_range_t
*vr
)
628 gcc_assert (vr
->type
!= VR_UNDEFINED
629 && vr
->type
!= VR_VARYING
630 && !symbolic_range_p (vr
));
632 zero
= build_int_cst (TREE_TYPE (vr
->min
), 0);
633 return (value_inside_range (zero
, vr
) == 1);
637 /* When extracting ranges from X_i = ASSERT_EXPR <Y_j, pred>, we will
638 initially consider X_i and Y_j equivalent, so the equivalence set
639 of Y_j is added to the equivalence set of X_i. However, it is
640 possible to have a chain of ASSERT_EXPRs whose predicates are
641 actually incompatible. This is usually the result of nesting of
642 contradictory if-then-else statements. For instance, in PR 24670:
644 count_4 has range [-INF, 63]
648 count_19 = ASSERT_EXPR <count_4, count_4 != 0>
651 count_18 = ASSERT_EXPR <count_19, count_19 > 63>
657 Notice that 'if (count_19 > 63)' is trivially false and will be
658 folded out at the end. However, during propagation, the flowgraph
659 is not cleaned up and so, VRP will evaluate predicates more
660 predicates than necessary, so it must support these
661 inconsistencies. The problem here is that because of the chaining
662 of ASSERT_EXPRs, the equivalency set for count_18 includes count_4.
663 Since count_4 has an incompatible range, we ICE when evaluating the
664 ranges in the equivalency set. So, we need to remove count_4 from
668 fix_equivalence_set (value_range_t
*vr_p
)
672 bitmap e
= vr_p
->equiv
;
673 bitmap to_remove
= BITMAP_ALLOC (NULL
);
675 /* Only detect inconsistencies on numeric ranges. */
676 if (vr_p
->type
== VR_VARYING
677 || vr_p
->type
== VR_UNDEFINED
678 || symbolic_range_p (vr_p
))
681 EXECUTE_IF_SET_IN_BITMAP (e
, 0, i
, bi
)
683 value_range_t
*equiv_vr
= vr_value
[i
];
685 if (equiv_vr
->type
== VR_VARYING
686 || equiv_vr
->type
== VR_UNDEFINED
687 || symbolic_range_p (equiv_vr
))
690 if (equiv_vr
->type
== VR_RANGE
691 && vr_p
->type
== VR_RANGE
692 && !value_ranges_intersect_p (vr_p
, equiv_vr
))
693 bitmap_set_bit (to_remove
, i
);
694 else if ((equiv_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_ANTI_RANGE
)
695 || (equiv_vr
->type
== VR_ANTI_RANGE
&& vr_p
->type
== VR_RANGE
))
697 /* A range and an anti-range have an empty intersection if
698 their end points are the same. FIXME,
699 value_ranges_intersect_p should handle this
701 if (compare_values (equiv_vr
->min
, vr_p
->min
) == 0
702 && compare_values (equiv_vr
->max
, vr_p
->max
) == 0)
703 bitmap_set_bit (to_remove
, i
);
707 bitmap_and_compl_into (vr_p
->equiv
, to_remove
);
708 BITMAP_FREE (to_remove
);
712 /* Extract value range information from an ASSERT_EXPR EXPR and store
716 extract_range_from_assert (value_range_t
*vr_p
, tree expr
)
718 tree var
, cond
, limit
, min
, max
, type
;
719 value_range_t
*var_vr
, *limit_vr
;
720 enum tree_code cond_code
;
722 var
= ASSERT_EXPR_VAR (expr
);
723 cond
= ASSERT_EXPR_COND (expr
);
725 gcc_assert (COMPARISON_CLASS_P (cond
));
727 /* Find VAR in the ASSERT_EXPR conditional. */
728 if (var
== TREE_OPERAND (cond
, 0))
730 /* If the predicate is of the form VAR COMP LIMIT, then we just
731 take LIMIT from the RHS and use the same comparison code. */
732 limit
= TREE_OPERAND (cond
, 1);
733 cond_code
= TREE_CODE (cond
);
737 /* If the predicate is of the form LIMIT COMP VAR, then we need
738 to flip around the comparison code to create the proper range
740 limit
= TREE_OPERAND (cond
, 0);
741 cond_code
= swap_tree_comparison (TREE_CODE (cond
));
744 type
= TREE_TYPE (limit
);
745 gcc_assert (limit
!= var
);
747 /* For pointer arithmetic, we only keep track of pointer equality
749 if (POINTER_TYPE_P (type
) && cond_code
!= NE_EXPR
&& cond_code
!= EQ_EXPR
)
751 set_value_range_to_varying (vr_p
);
755 /* If LIMIT is another SSA name and LIMIT has a range of its own,
756 try to use LIMIT's range to avoid creating symbolic ranges
758 limit_vr
= (TREE_CODE (limit
) == SSA_NAME
) ? get_value_range (limit
) : NULL
;
760 /* LIMIT's range is only interesting if it has any useful information. */
762 && (limit_vr
->type
== VR_UNDEFINED
763 || limit_vr
->type
== VR_VARYING
764 || symbolic_range_p (limit_vr
)))
767 /* Special handling for integral types with super-types. Some FEs
768 construct integral types derived from other types and restrict
769 the range of values these new types may take.
771 It may happen that LIMIT is actually smaller than TYPE's minimum
772 value. For instance, the Ada FE is generating code like this
775 D.1480_32 = nam_30 - 300000361;
776 if (D.1480_32 <= 1) goto <L112>; else goto <L52>;
778 D.1480_94 = ASSERT_EXPR <D.1480_32, D.1480_32 <= 1>;
780 All the names are of type types__name_id___XDLU_300000000__399999999
781 which has min == 300000000 and max == 399999999. This means that
782 the ASSERT_EXPR would try to create the range [3000000, 1] which
785 The fact that the type specifies MIN and MAX values does not
786 automatically mean that every variable of that type will always
787 be within that range, so the predicate may well be true at run
788 time. If we had symbolic -INF and +INF values, we could
789 represent this range, but we currently represent -INF and +INF
790 using the type's min and max values.
792 So, the only sensible thing we can do for now is set the
793 resulting range to VR_VARYING. TODO, would having symbolic -INF
794 and +INF values be worth the trouble? */
795 if (TREE_CODE (limit
) != SSA_NAME
796 && INTEGRAL_TYPE_P (type
)
799 if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
801 tree type_min
= TYPE_MIN_VALUE (type
);
802 int cmp
= compare_values (limit
, type_min
);
804 /* For < or <= comparisons, if LIMIT is smaller than
805 TYPE_MIN, set the range to VR_VARYING. */
806 if (cmp
== -1 || cmp
== 0)
808 set_value_range_to_varying (vr_p
);
812 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
814 tree type_max
= TYPE_MIN_VALUE (type
);
815 int cmp
= compare_values (limit
, type_max
);
817 /* For > or >= comparisons, if LIMIT is bigger than
818 TYPE_MAX, set the range to VR_VARYING. */
819 if (cmp
== 1 || cmp
== 0)
821 set_value_range_to_varying (vr_p
);
827 /* Initially, the new range has the same set of equivalences of
828 VAR's range. This will be revised before returning the final
829 value. Since assertions may be chained via mutually exclusive
830 predicates, we will need to trim the set of equivalences before
832 gcc_assert (vr_p
->equiv
== NULL
);
833 vr_p
->equiv
= BITMAP_ALLOC (NULL
);
834 add_equivalence (vr_p
->equiv
, var
);
836 /* Extract a new range based on the asserted comparison for VAR and
837 LIMIT's value range. Notice that if LIMIT has an anti-range, we
838 will only use it for equality comparisons (EQ_EXPR). For any
839 other kind of assertion, we cannot derive a range from LIMIT's
840 anti-range that can be used to describe the new range. For
841 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
842 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
843 no single range for x_2 that could describe LE_EXPR, so we might
844 as well build the range [b_4, +INF] for it. */
845 if (cond_code
== EQ_EXPR
)
847 enum value_range_type range_type
;
851 range_type
= limit_vr
->type
;
857 range_type
= VR_RANGE
;
862 set_value_range (vr_p
, range_type
, min
, max
, vr_p
->equiv
);
864 /* When asserting the equality VAR == LIMIT and LIMIT is another
865 SSA name, the new range will also inherit the equivalence set
867 if (TREE_CODE (limit
) == SSA_NAME
)
868 add_equivalence (vr_p
->equiv
, limit
);
870 else if (cond_code
== NE_EXPR
)
872 /* As described above, when LIMIT's range is an anti-range and
873 this assertion is an inequality (NE_EXPR), then we cannot
874 derive anything from the anti-range. For instance, if
875 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
876 not imply that VAR's range is [0, 0]. So, in the case of
877 anti-ranges, we just assert the inequality using LIMIT and
880 If LIMIT_VR is a range, we can only use it to build a new
881 anti-range if LIMIT_VR is a single-valued range. For
882 instance, if LIMIT_VR is [0, 1], the predicate
883 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
884 Rather, it means that for value 0 VAR should be ~[0, 0]
885 and for value 1, VAR should be ~[1, 1]. We cannot
886 represent these ranges.
888 The only situation in which we can build a valid
889 anti-range is when LIMIT_VR is a single-valued range
890 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
891 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
893 && limit_vr
->type
== VR_RANGE
894 && compare_values (limit_vr
->min
, limit_vr
->max
) == 0)
901 /* In any other case, we cannot use LIMIT's range to build a
906 /* If MIN and MAX cover the whole range for their type, then
907 just use the original LIMIT. */
908 if (INTEGRAL_TYPE_P (type
)
909 && min
== TYPE_MIN_VALUE (type
)
910 && max
== TYPE_MAX_VALUE (type
))
913 set_value_range (vr_p
, VR_ANTI_RANGE
, min
, max
, vr_p
->equiv
);
915 else if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
917 min
= TYPE_MIN_VALUE (type
);
919 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
923 /* If LIMIT_VR is of the form [N1, N2], we need to build the
924 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
929 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
930 if (cond_code
== LT_EXPR
)
932 tree one
= build_int_cst (type
, 1);
933 max
= fold_build2 (MINUS_EXPR
, type
, max
, one
);
936 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
938 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
940 max
= TYPE_MAX_VALUE (type
);
942 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
946 /* If LIMIT_VR is of the form [N1, N2], we need to build the
947 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
952 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
953 if (cond_code
== GT_EXPR
)
955 tree one
= build_int_cst (type
, 1);
956 min
= fold_build2 (PLUS_EXPR
, type
, min
, one
);
959 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
964 /* If VAR already had a known range, it may happen that the new
965 range we have computed and VAR's range are not compatible. For
969 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
971 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
973 While the above comes from a faulty program, it will cause an ICE
974 later because p_8 and p_6 will have incompatible ranges and at
975 the same time will be considered equivalent. A similar situation
979 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
981 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
983 Again i_6 and i_7 will have incompatible ranges. It would be
984 pointless to try and do anything with i_7's range because
985 anything dominated by 'if (i_5 < 5)' will be optimized away.
986 Note, due to the wa in which simulation proceeds, the statement
987 i_7 = ASSERT_EXPR <...> we would never be visited because the
988 conditional 'if (i_5 < 5)' always evaluates to false. However,
989 this extra check does not hurt and may protect against future
990 changes to VRP that may get into a situation similar to the
991 NULL pointer dereference example.
993 Note that these compatibility tests are only needed when dealing
994 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
995 are both anti-ranges, they will always be compatible, because two
996 anti-ranges will always have a non-empty intersection. */
998 var_vr
= get_value_range (var
);
1000 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1001 ranges or anti-ranges. */
1002 if (vr_p
->type
== VR_VARYING
1003 || vr_p
->type
== VR_UNDEFINED
1004 || var_vr
->type
== VR_VARYING
1005 || var_vr
->type
== VR_UNDEFINED
1006 || symbolic_range_p (vr_p
)
1007 || symbolic_range_p (var_vr
))
1010 if (var_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_RANGE
)
1012 /* If the two ranges have a non-empty intersection, we can
1013 refine the resulting range. Since the assert expression
1014 creates an equivalency and at the same time it asserts a
1015 predicate, we can take the intersection of the two ranges to
1016 get better precision. */
1017 if (value_ranges_intersect_p (var_vr
, vr_p
))
1019 /* Use the larger of the two minimums. */
1020 if (compare_values (vr_p
->min
, var_vr
->min
) == -1)
1025 /* Use the smaller of the two maximums. */
1026 if (compare_values (vr_p
->max
, var_vr
->max
) == 1)
1031 set_value_range (vr_p
, vr_p
->type
, min
, max
, vr_p
->equiv
);
1035 /* The two ranges do not intersect, set the new range to
1036 VARYING, because we will not be able to do anything
1037 meaningful with it. */
1038 set_value_range_to_varying (vr_p
);
1041 else if ((var_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_ANTI_RANGE
)
1042 || (var_vr
->type
== VR_ANTI_RANGE
&& vr_p
->type
== VR_RANGE
))
1044 /* A range and an anti-range will cancel each other only if
1045 their ends are the same. For instance, in the example above,
1046 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1047 so VR_P should be set to VR_VARYING. */
1048 if (compare_values (var_vr
->min
, vr_p
->min
) == 0
1049 && compare_values (var_vr
->max
, vr_p
->max
) == 0)
1050 set_value_range_to_varying (vr_p
);
1053 tree min
, max
, anti_min
, anti_max
, real_min
, real_max
;
1055 /* We want to compute the logical AND of the two ranges;
1056 there are three cases to consider.
1059 1. The VR_ANTI_RANGE range is competely within the
1060 VR_RANGE and the endpoints of the ranges are
1061 different. In that case the resulting range
1062 should be whichever range is more precise.
1063 Typically that will be the VR_RANGE.
1065 2. The VR_ANTI_RANGE is completely disjoint from
1066 the VR_RANGE. In this case the resulting range
1067 should be the VR_RANGE.
1069 3. There is some overlap between the VR_ANTI_RANGE
1072 3a. If the high limit of the VR_ANTI_RANGE resides
1073 within the VR_RANGE, then the result is a new
1074 VR_RANGE starting at the high limit of the
1075 the VR_ANTI_RANGE + 1 and extending to the
1076 high limit of the original VR_RANGE.
1078 3b. If the low limit of the VR_ANTI_RANGE resides
1079 within the VR_RANGE, then the result is a new
1080 VR_RANGE starting at the low limit of the original
1081 VR_RANGE and extending to the low limit of the
1082 VR_ANTI_RANGE - 1. */
1083 if (vr_p
->type
== VR_ANTI_RANGE
)
1085 anti_min
= vr_p
->min
;
1086 anti_max
= vr_p
->max
;
1087 real_min
= var_vr
->min
;
1088 real_max
= var_vr
->max
;
1092 anti_min
= var_vr
->min
;
1093 anti_max
= var_vr
->max
;
1094 real_min
= vr_p
->min
;
1095 real_max
= vr_p
->max
;
1099 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1100 not including any endpoints. */
1101 if (compare_values (anti_max
, real_max
) == -1
1102 && compare_values (anti_min
, real_min
) == 1)
1104 set_value_range (vr_p
, VR_RANGE
, real_min
,
1105 real_max
, vr_p
->equiv
);
1107 /* Case 2, VR_ANTI_RANGE completely disjoint from
1109 else if (compare_values (anti_min
, real_max
) == 1
1110 || compare_values (anti_max
, real_min
) == -1)
1112 set_value_range (vr_p
, VR_RANGE
, real_min
,
1113 real_max
, vr_p
->equiv
);
1115 /* Case 3a, the anti-range extends into the low
1116 part of the real range. Thus creating a new
1117 low for the real reange. */
1118 else if ((compare_values (anti_max
, real_min
) == 1
1119 || compare_values (anti_max
, real_min
) == 0)
1120 && compare_values (anti_max
, real_max
) == -1)
1122 min
= fold_build2 (PLUS_EXPR
, TREE_TYPE (var_vr
->min
),
1124 build_int_cst (TREE_TYPE (var_vr
->min
), 1));
1126 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1128 /* Case 3b, the anti-range extends into the high
1129 part of the real range. Thus creating a new
1130 higher for the real reange. */
1131 else if (compare_values (anti_min
, real_min
) == 1
1132 && (compare_values (anti_min
, real_max
) == -1
1133 || compare_values (anti_min
, real_max
) == 0))
1135 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (var_vr
->min
),
1137 build_int_cst (TREE_TYPE (var_vr
->min
), 1));
1139 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1144 /* Remove names from the equivalence set that have ranges
1145 incompatible with VR_P. */
1147 fix_equivalence_set (vr_p
);
1151 /* Extract range information from SSA name VAR and store it in VR. If
1152 VAR has an interesting range, use it. Otherwise, create the
1153 range [VAR, VAR] and return it. This is useful in situations where
1154 we may have conditionals testing values of VARYING names. For
1161 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1165 extract_range_from_ssa_name (value_range_t
*vr
, tree var
)
1167 value_range_t
*var_vr
= get_value_range (var
);
1169 if (var_vr
->type
!= VR_UNDEFINED
&& var_vr
->type
!= VR_VARYING
)
1170 copy_value_range (vr
, var_vr
);
1172 set_value_range (vr
, VR_RANGE
, var
, var
, NULL
);
1174 add_equivalence (vr
->equiv
, var
);
1178 /* Wrapper around int_const_binop. If the operation overflows and we
1179 are not using wrapping arithmetic, then adjust the result to be
1180 -INF or +INF depending on CODE, VAL1 and VAL2. */
1183 vrp_int_const_binop (enum tree_code code
, tree val1
, tree val2
)
1188 return int_const_binop (code
, val1
, val2
, 0);
1190 /* If we are not using wrapping arithmetic, operate symbolically
1191 on -INF and +INF. */
1192 res
= int_const_binop (code
, val1
, val2
, 0);
1194 if (TYPE_UNSIGNED (TREE_TYPE (val1
)))
1196 int checkz
= compare_values (res
, val1
);
1198 /* Ensure that res = val1 + val2 >= val1
1199 or that res = val1 - val2 <= val1. */
1200 if ((code
== PLUS_EXPR
&& !(checkz
== 1 || checkz
== 0))
1201 || (code
== MINUS_EXPR
&& !(checkz
== 0 || checkz
== -1)))
1203 res
= copy_node (res
);
1204 TREE_OVERFLOW (res
) = 1;
1207 /* If the operation overflowed but neither VAL1 nor VAL2 are
1208 overflown, return -INF or +INF depending on the operation
1209 and the combination of signs of the operands. */
1210 else if (TREE_OVERFLOW (res
)
1211 && !TREE_OVERFLOW (val1
)
1212 && !TREE_OVERFLOW (val2
))
1214 int sgn1
= tree_int_cst_sgn (val1
);
1215 int sgn2
= tree_int_cst_sgn (val2
);
1217 /* Notice that we only need to handle the restricted set of
1218 operations handled by extract_range_from_binary_expr.
1219 Among them, only multiplication, addition and subtraction
1220 can yield overflow without overflown operands because we
1221 are working with integral types only... except in the
1222 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1223 for division too. */
1225 /* For multiplication, the sign of the overflow is given
1226 by the comparison of the signs of the operands. */
1227 if ((code
== MULT_EXPR
&& sgn1
== sgn2
)
1228 /* For addition, the operands must be of the same sign
1229 to yield an overflow. Its sign is therefore that
1230 of one of the operands, for example the first. */
1231 || (code
== PLUS_EXPR
&& sgn1
> 0)
1232 /* For subtraction, the operands must be of different
1233 signs to yield an overflow. Its sign is therefore
1234 that of the first operand or the opposite of that
1235 of the second operand. A first operand of 0 counts
1236 as positive here, for the corner case 0 - (-INF),
1237 which overflows, but must yield +INF. */
1238 || (code
== MINUS_EXPR
&& sgn1
>= 0)
1239 /* For division, the only case is -INF / -1 = +INF. */
1240 || code
== TRUNC_DIV_EXPR
1241 || code
== FLOOR_DIV_EXPR
1242 || code
== CEIL_DIV_EXPR
1243 || code
== EXACT_DIV_EXPR
1244 || code
== ROUND_DIV_EXPR
)
1245 return TYPE_MAX_VALUE (TREE_TYPE (res
));
1247 return TYPE_MIN_VALUE (TREE_TYPE (res
));
1254 /* Extract range information from a binary expression EXPR based on
1255 the ranges of each of its operands and the expression code. */
1258 extract_range_from_binary_expr (value_range_t
*vr
, tree expr
)
1260 enum tree_code code
= TREE_CODE (expr
);
1261 enum value_range_type type
;
1262 tree op0
, op1
, min
, max
;
1264 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1265 value_range_t vr1
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1267 /* Not all binary expressions can be applied to ranges in a
1268 meaningful way. Handle only arithmetic operations. */
1269 if (code
!= PLUS_EXPR
1270 && code
!= MINUS_EXPR
1271 && code
!= MULT_EXPR
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
1279 && code
!= BIT_AND_EXPR
1280 && code
!= TRUTH_ANDIF_EXPR
1281 && code
!= TRUTH_ORIF_EXPR
1282 && code
!= TRUTH_AND_EXPR
1283 && code
!= TRUTH_OR_EXPR
1284 && code
!= TRUTH_XOR_EXPR
)
1286 set_value_range_to_varying (vr
);
1290 /* Get value ranges for each operand. For constant operands, create
1291 a new value range with the operand to simplify processing. */
1292 op0
= TREE_OPERAND (expr
, 0);
1293 if (TREE_CODE (op0
) == SSA_NAME
)
1294 vr0
= *(get_value_range (op0
));
1295 else if (is_gimple_min_invariant (op0
))
1296 set_value_range (&vr0
, VR_RANGE
, op0
, op0
, NULL
);
1298 set_value_range_to_varying (&vr0
);
1300 op1
= TREE_OPERAND (expr
, 1);
1301 if (TREE_CODE (op1
) == SSA_NAME
)
1302 vr1
= *(get_value_range (op1
));
1303 else if (is_gimple_min_invariant (op1
))
1304 set_value_range (&vr1
, VR_RANGE
, op1
, op1
, NULL
);
1306 set_value_range_to_varying (&vr1
);
1308 /* If either range is UNDEFINED, so is the result. */
1309 if (vr0
.type
== VR_UNDEFINED
|| vr1
.type
== VR_UNDEFINED
)
1311 set_value_range_to_undefined (vr
);
1315 /* The type of the resulting value range defaults to VR0.TYPE. */
1318 /* Refuse to operate on VARYING ranges, ranges of different kinds
1319 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1320 because we may be able to derive a useful range even if one of
1321 the operands is VR_VARYING or symbolic range. TODO, we may be
1322 able to derive anti-ranges in some cases. */
1323 if (code
!= BIT_AND_EXPR
1324 && code
!= TRUTH_AND_EXPR
1325 && code
!= TRUTH_OR_EXPR
1326 && (vr0
.type
== VR_VARYING
1327 || vr1
.type
== VR_VARYING
1328 || vr0
.type
!= vr1
.type
1329 || symbolic_range_p (&vr0
)
1330 || symbolic_range_p (&vr1
)))
1332 set_value_range_to_varying (vr
);
1336 /* Now evaluate the expression to determine the new range. */
1337 if (POINTER_TYPE_P (TREE_TYPE (expr
))
1338 || POINTER_TYPE_P (TREE_TYPE (op0
))
1339 || POINTER_TYPE_P (TREE_TYPE (op1
)))
1341 /* For pointer types, we are really only interested in asserting
1342 whether the expression evaluates to non-NULL. FIXME, we used
1343 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1344 ivopts is generating expressions with pointer multiplication
1346 if (code
== PLUS_EXPR
)
1348 if (range_is_nonnull (&vr0
) || range_is_nonnull (&vr1
))
1349 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1350 else if (range_is_null (&vr0
) && range_is_null (&vr1
))
1351 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1353 set_value_range_to_varying (vr
);
1357 /* Subtracting from a pointer, may yield 0, so just drop the
1358 resulting range to varying. */
1359 set_value_range_to_varying (vr
);
1365 /* For integer ranges, apply the operation to each end of the
1366 range and see what we end up with. */
1367 if (code
== TRUTH_ANDIF_EXPR
1368 || code
== TRUTH_ORIF_EXPR
1369 || code
== TRUTH_AND_EXPR
1370 || code
== TRUTH_OR_EXPR
1371 || code
== TRUTH_XOR_EXPR
)
1373 /* If one of the operands is zero, we know that the whole
1374 expression evaluates zero. */
1375 if (code
== TRUTH_AND_EXPR
1376 && ((vr0
.type
== VR_RANGE
1377 && integer_zerop (vr0
.min
)
1378 && integer_zerop (vr0
.max
))
1379 || (vr1
.type
== VR_RANGE
1380 && integer_zerop (vr1
.min
)
1381 && integer_zerop (vr1
.max
))))
1384 min
= max
= build_int_cst (TREE_TYPE (expr
), 0);
1386 /* If one of the operands is one, we know that the whole
1387 expression evaluates one. */
1388 else if (code
== TRUTH_OR_EXPR
1389 && ((vr0
.type
== VR_RANGE
1390 && integer_onep (vr0
.min
)
1391 && integer_onep (vr0
.max
))
1392 || (vr1
.type
== VR_RANGE
1393 && integer_onep (vr1
.min
)
1394 && integer_onep (vr1
.max
))))
1397 min
= max
= build_int_cst (TREE_TYPE (expr
), 1);
1399 else if (vr0
.type
!= VR_VARYING
1400 && vr1
.type
!= VR_VARYING
1401 && vr0
.type
== vr1
.type
1402 && !symbolic_range_p (&vr0
)
1403 && !symbolic_range_p (&vr1
))
1405 /* Boolean expressions cannot be folded with int_const_binop. */
1406 min
= fold_binary (code
, TREE_TYPE (expr
), vr0
.min
, vr1
.min
);
1407 max
= fold_binary (code
, TREE_TYPE (expr
), vr0
.max
, vr1
.max
);
1411 set_value_range_to_varying (vr
);
1415 else if (code
== PLUS_EXPR
1417 || code
== MAX_EXPR
)
1419 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1420 VR_VARYING. It would take more effort to compute a precise
1421 range for such a case. For example, if we have op0 == 1 and
1422 op1 == -1 with their ranges both being ~[0,0], we would have
1423 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1424 Note that we are guaranteed to have vr0.type == vr1.type at
1426 if (code
== PLUS_EXPR
&& vr0
.type
== VR_ANTI_RANGE
)
1428 set_value_range_to_varying (vr
);
1432 /* For operations that make the resulting range directly
1433 proportional to the original ranges, apply the operation to
1434 the same end of each range. */
1435 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1436 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.max
);
1438 else if (code
== MULT_EXPR
1439 || code
== TRUNC_DIV_EXPR
1440 || code
== FLOOR_DIV_EXPR
1441 || code
== CEIL_DIV_EXPR
1442 || code
== EXACT_DIV_EXPR
1443 || code
== ROUND_DIV_EXPR
)
1448 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1449 drop to VR_VARYING. It would take more effort to compute a
1450 precise range for such a case. For example, if we have
1451 op0 == 65536 and op1 == 65536 with their ranges both being
1452 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1453 we cannot claim that the product is in ~[0,0]. Note that we
1454 are guaranteed to have vr0.type == vr1.type at this
1456 if (code
== MULT_EXPR
1457 && vr0
.type
== VR_ANTI_RANGE
1458 && (flag_wrapv
|| TYPE_UNSIGNED (TREE_TYPE (op0
))))
1460 set_value_range_to_varying (vr
);
1464 /* Multiplications and divisions are a bit tricky to handle,
1465 depending on the mix of signs we have in the two ranges, we
1466 need to operate on different values to get the minimum and
1467 maximum values for the new range. One approach is to figure
1468 out all the variations of range combinations and do the
1471 However, this involves several calls to compare_values and it
1472 is pretty convoluted. It's simpler to do the 4 operations
1473 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1474 MAX1) and then figure the smallest and largest values to form
1477 /* Divisions by zero result in a VARYING value. */
1478 if (code
!= MULT_EXPR
1479 && (vr0
.type
== VR_ANTI_RANGE
|| range_includes_zero_p (&vr1
)))
1481 set_value_range_to_varying (vr
);
1485 /* Compute the 4 cross operations. */
1486 val
[0] = vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1488 val
[1] = (vr1
.max
!= vr1
.min
)
1489 ? vrp_int_const_binop (code
, vr0
.min
, vr1
.max
)
1492 val
[2] = (vr0
.max
!= vr0
.min
)
1493 ? vrp_int_const_binop (code
, vr0
.max
, vr1
.min
)
1496 val
[3] = (vr0
.min
!= vr0
.max
&& vr1
.min
!= vr1
.max
)
1497 ? vrp_int_const_binop (code
, vr0
.max
, vr1
.max
)
1500 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1504 for (i
= 1; i
< 4; i
++)
1506 if (!is_gimple_min_invariant (min
) || TREE_OVERFLOW (min
)
1507 || !is_gimple_min_invariant (max
) || TREE_OVERFLOW (max
))
1512 if (!is_gimple_min_invariant (val
[i
]) || TREE_OVERFLOW (val
[i
]))
1514 /* If we found an overflowed value, set MIN and MAX
1515 to it so that we set the resulting range to
1521 if (compare_values (val
[i
], min
) == -1)
1524 if (compare_values (val
[i
], max
) == 1)
1529 else if (code
== MINUS_EXPR
)
1531 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1532 VR_VARYING. It would take more effort to compute a precise
1533 range for such a case. For example, if we have op0 == 1 and
1534 op1 == 1 with their ranges both being ~[0,0], we would have
1535 op0 - op1 == 0, so we cannot claim that the difference is in
1536 ~[0,0]. Note that we are guaranteed to have
1537 vr0.type == vr1.type at this point. */
1538 if (vr0
.type
== VR_ANTI_RANGE
)
1540 set_value_range_to_varying (vr
);
1544 /* For MINUS_EXPR, apply the operation to the opposite ends of
1546 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.max
);
1547 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.min
);
1549 else if (code
== BIT_AND_EXPR
)
1551 if (vr0
.type
== VR_RANGE
1552 && vr0
.min
== vr0
.max
1553 && tree_expr_nonnegative_p (vr0
.max
)
1554 && TREE_CODE (vr0
.max
) == INTEGER_CST
)
1556 min
= build_int_cst (TREE_TYPE (expr
), 0);
1559 else if (vr1
.type
== VR_RANGE
1560 && vr1
.min
== vr1
.max
1561 && tree_expr_nonnegative_p (vr1
.max
)
1562 && TREE_CODE (vr1
.max
) == INTEGER_CST
)
1565 min
= build_int_cst (TREE_TYPE (expr
), 0);
1570 set_value_range_to_varying (vr
);
1577 /* If either MIN or MAX overflowed, then set the resulting range to
1579 if (!is_gimple_min_invariant (min
) || TREE_OVERFLOW (min
)
1580 || !is_gimple_min_invariant (max
) || TREE_OVERFLOW (max
))
1582 set_value_range_to_varying (vr
);
1586 cmp
= compare_values (min
, max
);
1587 if (cmp
== -2 || cmp
== 1)
1589 /* If the new range has its limits swapped around (MIN > MAX),
1590 then the operation caused one of them to wrap around, mark
1591 the new range VARYING. */
1592 set_value_range_to_varying (vr
);
1595 set_value_range (vr
, type
, min
, max
, NULL
);
1599 /* Extract range information from a unary expression EXPR based on
1600 the range of its operand and the expression code. */
1603 extract_range_from_unary_expr (value_range_t
*vr
, tree expr
)
1605 enum tree_code code
= TREE_CODE (expr
);
1608 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1610 /* Refuse to operate on certain unary expressions for which we
1611 cannot easily determine a resulting range. */
1612 if (code
== FIX_TRUNC_EXPR
1613 || code
== FIX_CEIL_EXPR
1614 || code
== FIX_FLOOR_EXPR
1615 || code
== FIX_ROUND_EXPR
1616 || code
== FLOAT_EXPR
1617 || code
== BIT_NOT_EXPR
1618 || code
== NON_LVALUE_EXPR
1619 || code
== CONJ_EXPR
)
1621 set_value_range_to_varying (vr
);
1625 /* Get value ranges for the operand. For constant operands, create
1626 a new value range with the operand to simplify processing. */
1627 op0
= TREE_OPERAND (expr
, 0);
1628 if (TREE_CODE (op0
) == SSA_NAME
)
1629 vr0
= *(get_value_range (op0
));
1630 else if (is_gimple_min_invariant (op0
))
1631 set_value_range (&vr0
, VR_RANGE
, op0
, op0
, NULL
);
1633 set_value_range_to_varying (&vr0
);
1635 /* If VR0 is UNDEFINED, so is the result. */
1636 if (vr0
.type
== VR_UNDEFINED
)
1638 set_value_range_to_undefined (vr
);
1642 /* Refuse to operate on varying and symbolic ranges. Also, if the
1643 operand is neither a pointer nor an integral type, set the
1644 resulting range to VARYING. TODO, in some cases we may be able
1645 to derive anti-ranges (like nonzero values). */
1646 if (vr0
.type
== VR_VARYING
1647 || (!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
1648 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
1649 || symbolic_range_p (&vr0
))
1651 set_value_range_to_varying (vr
);
1655 /* If the expression involves pointers, we are only interested in
1656 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1657 if (POINTER_TYPE_P (TREE_TYPE (expr
)) || POINTER_TYPE_P (TREE_TYPE (op0
)))
1659 if (range_is_nonnull (&vr0
) || tree_expr_nonzero_p (expr
))
1660 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1661 else if (range_is_null (&vr0
))
1662 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1664 set_value_range_to_varying (vr
);
1669 /* Handle unary expressions on integer ranges. */
1670 if (code
== NOP_EXPR
|| code
== CONVERT_EXPR
)
1672 tree inner_type
= TREE_TYPE (op0
);
1673 tree outer_type
= TREE_TYPE (expr
);
1675 /* If VR0 represents a simple range, then try to convert
1676 the min and max values for the range to the same type
1677 as OUTER_TYPE. If the results compare equal to VR0's
1678 min and max values and the new min is still less than
1679 or equal to the new max, then we can safely use the newly
1680 computed range for EXPR. This allows us to compute
1681 accurate ranges through many casts. */
1682 if (vr0
.type
== VR_RANGE
)
1684 tree new_min
, new_max
;
1686 /* Convert VR0's min/max to OUTER_TYPE. */
1687 new_min
= fold_convert (outer_type
, vr0
.min
);
1688 new_max
= fold_convert (outer_type
, vr0
.max
);
1690 /* Verify the new min/max values are gimple values and
1691 that they compare equal to VR0's min/max values. */
1692 if (is_gimple_val (new_min
)
1693 && is_gimple_val (new_max
)
1694 && tree_int_cst_equal (new_min
, vr0
.min
)
1695 && tree_int_cst_equal (new_max
, vr0
.max
)
1696 && compare_values (new_min
, new_max
) <= 0
1697 && compare_values (new_min
, new_max
) >= -1)
1699 set_value_range (vr
, VR_RANGE
, new_min
, new_max
, vr
->equiv
);
1704 /* When converting types of different sizes, set the result to
1705 VARYING. Things like sign extensions and precision loss may
1706 change the range. For instance, if x_3 is of type 'long long
1707 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1708 is impossible to know at compile time whether y_5 will be
1710 if (TYPE_SIZE (inner_type
) != TYPE_SIZE (outer_type
)
1711 || TYPE_PRECISION (inner_type
) != TYPE_PRECISION (outer_type
))
1713 set_value_range_to_varying (vr
);
1718 /* Apply the operation to each end of the range and see what we end
1720 if (code
== NEGATE_EXPR
1721 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
1723 /* NEGATE_EXPR flips the range around. */
1724 min
= (vr0
.max
== TYPE_MAX_VALUE (TREE_TYPE (expr
)) && !flag_wrapv
)
1725 ? TYPE_MIN_VALUE (TREE_TYPE (expr
))
1726 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1728 max
= (vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
)) && !flag_wrapv
)
1729 ? TYPE_MAX_VALUE (TREE_TYPE (expr
))
1730 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1732 else if (code
== ABS_EXPR
1733 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
1735 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1738 && ((vr0
.type
== VR_RANGE
1739 && vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
)))
1740 || (vr0
.type
== VR_ANTI_RANGE
1741 && vr0
.min
!= TYPE_MIN_VALUE (TREE_TYPE (expr
))
1742 && !range_includes_zero_p (&vr0
))))
1744 set_value_range_to_varying (vr
);
1748 /* ABS_EXPR may flip the range around, if the original range
1749 included negative values. */
1750 min
= (vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
)))
1751 ? TYPE_MAX_VALUE (TREE_TYPE (expr
))
1752 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1754 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1756 cmp
= compare_values (min
, max
);
1758 /* If a VR_ANTI_RANGEs contains zero, then we have
1759 ~[-INF, min(MIN, MAX)]. */
1760 if (vr0
.type
== VR_ANTI_RANGE
)
1762 if (range_includes_zero_p (&vr0
))
1764 tree type_min_value
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
1766 /* Take the lower of the two values. */
1770 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1771 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1772 flag_wrapv is set and the original anti-range doesn't include
1773 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1774 min
= (flag_wrapv
&& vr0
.min
!= type_min_value
1775 ? int_const_binop (PLUS_EXPR
,
1777 integer_one_node
, 0)
1782 /* All else has failed, so create the range [0, INF], even for
1783 flag_wrapv since TYPE_MIN_VALUE is in the original
1785 vr0
.type
= VR_RANGE
;
1786 min
= build_int_cst (TREE_TYPE (expr
), 0);
1787 max
= TYPE_MAX_VALUE (TREE_TYPE (expr
));
1791 /* If the range contains zero then we know that the minimum value in the
1792 range will be zero. */
1793 else if (range_includes_zero_p (&vr0
))
1797 min
= build_int_cst (TREE_TYPE (expr
), 0);
1801 /* If the range was reversed, swap MIN and MAX. */
1812 /* Otherwise, operate on each end of the range. */
1813 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1814 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1817 cmp
= compare_values (min
, max
);
1818 if (cmp
== -2 || cmp
== 1)
1820 /* If the new range has its limits swapped around (MIN > MAX),
1821 then the operation caused one of them to wrap around, mark
1822 the new range VARYING. */
1823 set_value_range_to_varying (vr
);
1826 set_value_range (vr
, vr0
.type
, min
, max
, NULL
);
1830 /* Extract range information from a comparison expression EXPR based
1831 on the range of its operand and the expression code. */
1834 extract_range_from_comparison (value_range_t
*vr
, tree expr
)
1836 tree val
= vrp_evaluate_conditional (expr
, false);
1839 /* Since this expression was found on the RHS of an assignment,
1840 its type may be different from _Bool. Convert VAL to EXPR's
1842 val
= fold_convert (TREE_TYPE (expr
), val
);
1843 set_value_range (vr
, VR_RANGE
, val
, val
, vr
->equiv
);
1846 set_value_range_to_varying (vr
);
1850 /* Try to compute a useful range out of expression EXPR and store it
1854 extract_range_from_expr (value_range_t
*vr
, tree expr
)
1856 enum tree_code code
= TREE_CODE (expr
);
1858 if (code
== ASSERT_EXPR
)
1859 extract_range_from_assert (vr
, expr
);
1860 else if (code
== SSA_NAME
)
1861 extract_range_from_ssa_name (vr
, expr
);
1862 else if (TREE_CODE_CLASS (code
) == tcc_binary
1863 || code
== TRUTH_ANDIF_EXPR
1864 || code
== TRUTH_ORIF_EXPR
1865 || code
== TRUTH_AND_EXPR
1866 || code
== TRUTH_OR_EXPR
1867 || code
== TRUTH_XOR_EXPR
)
1868 extract_range_from_binary_expr (vr
, expr
);
1869 else if (TREE_CODE_CLASS (code
) == tcc_unary
)
1870 extract_range_from_unary_expr (vr
, expr
);
1871 else if (TREE_CODE_CLASS (code
) == tcc_comparison
)
1872 extract_range_from_comparison (vr
, expr
);
1873 else if (is_gimple_min_invariant (expr
))
1874 set_value_range (vr
, VR_RANGE
, expr
, expr
, NULL
);
1875 else if (vrp_expr_computes_nonzero (expr
))
1876 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1878 set_value_range_to_varying (vr
);
1881 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1882 would be profitable to adjust VR using scalar evolution information
1883 for VAR. If so, update VR with the new limits. */
1886 adjust_range_with_scev (value_range_t
*vr
, struct loop
*loop
, tree stmt
,
1889 tree init
, step
, chrec
;
1890 bool init_is_max
, unknown_max
;
1892 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1893 better opportunities than a regular range, but I'm not sure. */
1894 if (vr
->type
== VR_ANTI_RANGE
)
1897 chrec
= instantiate_parameters (loop
, analyze_scalar_evolution (loop
, var
));
1898 if (TREE_CODE (chrec
) != POLYNOMIAL_CHREC
)
1901 init
= initial_condition_in_loop_num (chrec
, loop
->num
);
1902 step
= evolution_part_in_loop_num (chrec
, loop
->num
);
1904 /* If STEP is symbolic, we can't know whether INIT will be the
1905 minimum or maximum value in the range. */
1906 if (step
== NULL_TREE
1907 || !is_gimple_min_invariant (step
))
1910 /* Do not adjust ranges when chrec may wrap. */
1911 if (scev_probably_wraps_p (chrec_type (chrec
), init
, step
, stmt
,
1912 cfg_loops
->parray
[CHREC_VARIABLE (chrec
)],
1913 &init_is_max
, &unknown_max
)
1917 if (!POINTER_TYPE_P (TREE_TYPE (init
))
1918 && (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
))
1920 /* For VARYING or UNDEFINED ranges, just about anything we get
1921 from scalar evolutions should be better. */
1922 tree min
= TYPE_MIN_VALUE (TREE_TYPE (init
));
1923 tree max
= TYPE_MAX_VALUE (TREE_TYPE (init
));
1930 /* If we would create an invalid range, then just assume we
1931 know absolutely nothing. This may be over-conservative,
1932 but it's clearly safe. */
1933 if (compare_values (min
, max
) == 1)
1936 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
1938 else if (vr
->type
== VR_RANGE
)
1945 /* INIT is the maximum value. If INIT is lower than VR->MAX
1946 but no smaller than VR->MIN, set VR->MAX to INIT. */
1947 if (compare_values (init
, max
) == -1)
1951 /* If we just created an invalid range with the minimum
1952 greater than the maximum, take the minimum all the
1954 if (compare_values (min
, max
) == 1)
1955 min
= TYPE_MIN_VALUE (TREE_TYPE (min
));
1960 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
1961 if (compare_values (init
, min
) == 1)
1965 /* If we just created an invalid range with the minimum
1966 greater than the maximum, take the maximum all the
1968 if (compare_values (min
, max
) == 1)
1969 max
= TYPE_MAX_VALUE (TREE_TYPE (max
));
1973 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
1978 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
1980 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
1981 all the values in the ranges.
1983 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
1985 - Return NULL_TREE if it is not always possible to determine the
1986 value of the comparison. */
1990 compare_ranges (enum tree_code comp
, value_range_t
*vr0
, value_range_t
*vr1
)
1992 /* VARYING or UNDEFINED ranges cannot be compared. */
1993 if (vr0
->type
== VR_VARYING
1994 || vr0
->type
== VR_UNDEFINED
1995 || vr1
->type
== VR_VARYING
1996 || vr1
->type
== VR_UNDEFINED
)
1999 /* Anti-ranges need to be handled separately. */
2000 if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
2002 /* If both are anti-ranges, then we cannot compute any
2004 if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
2007 /* These comparisons are never statically computable. */
2014 /* Equality can be computed only between a range and an
2015 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2016 if (vr0
->type
== VR_RANGE
)
2018 /* To simplify processing, make VR0 the anti-range. */
2019 value_range_t
*tmp
= vr0
;
2024 gcc_assert (comp
== NE_EXPR
|| comp
== EQ_EXPR
);
2026 if (compare_values (vr0
->min
, vr1
->min
) == 0
2027 && compare_values (vr0
->max
, vr1
->max
) == 0)
2028 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
2033 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2034 operands around and change the comparison code. */
2035 if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
2038 comp
= (comp
== GT_EXPR
) ? LT_EXPR
: LE_EXPR
;
2044 if (comp
== EQ_EXPR
)
2046 /* Equality may only be computed if both ranges represent
2047 exactly one value. */
2048 if (compare_values (vr0
->min
, vr0
->max
) == 0
2049 && compare_values (vr1
->min
, vr1
->max
) == 0)
2051 int cmp_min
= compare_values (vr0
->min
, vr1
->min
);
2052 int cmp_max
= compare_values (vr0
->max
, vr1
->max
);
2053 if (cmp_min
== 0 && cmp_max
== 0)
2054 return boolean_true_node
;
2055 else if (cmp_min
!= -2 && cmp_max
!= -2)
2056 return boolean_false_node
;
2058 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2059 else if (compare_values (vr0
->min
, vr1
->max
) == 1
2060 || compare_values (vr1
->min
, vr0
->max
) == 1)
2061 return boolean_false_node
;
2065 else if (comp
== NE_EXPR
)
2069 /* If VR0 is completely to the left or completely to the right
2070 of VR1, they are always different. Notice that we need to
2071 make sure that both comparisons yield similar results to
2072 avoid comparing values that cannot be compared at
2074 cmp1
= compare_values (vr0
->max
, vr1
->min
);
2075 cmp2
= compare_values (vr0
->min
, vr1
->max
);
2076 if ((cmp1
== -1 && cmp2
== -1) || (cmp1
== 1 && cmp2
== 1))
2077 return boolean_true_node
;
2079 /* If VR0 and VR1 represent a single value and are identical,
2081 else if (compare_values (vr0
->min
, vr0
->max
) == 0
2082 && compare_values (vr1
->min
, vr1
->max
) == 0
2083 && compare_values (vr0
->min
, vr1
->min
) == 0
2084 && compare_values (vr0
->max
, vr1
->max
) == 0)
2085 return boolean_false_node
;
2087 /* Otherwise, they may or may not be different. */
2091 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
2095 /* If VR0 is to the left of VR1, return true. */
2096 tst
= compare_values (vr0
->max
, vr1
->min
);
2097 if ((comp
== LT_EXPR
&& tst
== -1)
2098 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
2099 return boolean_true_node
;
2101 /* If VR0 is to the right of VR1, return false. */
2102 tst
= compare_values (vr0
->min
, vr1
->max
);
2103 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
2104 || (comp
== LE_EXPR
&& tst
== 1))
2105 return boolean_false_node
;
2107 /* Otherwise, we don't know. */
2115 /* Given a value range VR, a value VAL and a comparison code COMP, return
2116 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2117 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2118 always returns false. Return NULL_TREE if it is not always
2119 possible to determine the value of the comparison. */
2122 compare_range_with_value (enum tree_code comp
, value_range_t
*vr
, tree val
)
2124 if (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
)
2127 /* Anti-ranges need to be handled separately. */
2128 if (vr
->type
== VR_ANTI_RANGE
)
2130 /* For anti-ranges, the only predicates that we can compute at
2131 compile time are equality and inequality. */
2138 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2139 if (value_inside_range (val
, vr
) == 1)
2140 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
2145 if (comp
== EQ_EXPR
)
2147 /* EQ_EXPR may only be computed if VR represents exactly
2149 if (compare_values (vr
->min
, vr
->max
) == 0)
2151 int cmp
= compare_values (vr
->min
, val
);
2153 return boolean_true_node
;
2154 else if (cmp
== -1 || cmp
== 1 || cmp
== 2)
2155 return boolean_false_node
;
2157 else if (compare_values (val
, vr
->min
) == -1
2158 || compare_values (vr
->max
, val
) == -1)
2159 return boolean_false_node
;
2163 else if (comp
== NE_EXPR
)
2165 /* If VAL is not inside VR, then they are always different. */
2166 if (compare_values (vr
->max
, val
) == -1
2167 || compare_values (vr
->min
, val
) == 1)
2168 return boolean_true_node
;
2170 /* If VR represents exactly one value equal to VAL, then return
2172 if (compare_values (vr
->min
, vr
->max
) == 0
2173 && compare_values (vr
->min
, val
) == 0)
2174 return boolean_false_node
;
2176 /* Otherwise, they may or may not be different. */
2179 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
2183 /* If VR is to the left of VAL, return true. */
2184 tst
= compare_values (vr
->max
, val
);
2185 if ((comp
== LT_EXPR
&& tst
== -1)
2186 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
2187 return boolean_true_node
;
2189 /* If VR is to the right of VAL, return false. */
2190 tst
= compare_values (vr
->min
, val
);
2191 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
2192 || (comp
== LE_EXPR
&& tst
== 1))
2193 return boolean_false_node
;
2195 /* Otherwise, we don't know. */
2198 else if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
2202 /* If VR is to the right of VAL, return true. */
2203 tst
= compare_values (vr
->min
, val
);
2204 if ((comp
== GT_EXPR
&& tst
== 1)
2205 || (comp
== GE_EXPR
&& (tst
== 0 || tst
== 1)))
2206 return boolean_true_node
;
2208 /* If VR is to the left of VAL, return false. */
2209 tst
= compare_values (vr
->max
, val
);
2210 if ((comp
== GT_EXPR
&& (tst
== -1 || tst
== 0))
2211 || (comp
== GE_EXPR
&& tst
== -1))
2212 return boolean_false_node
;
2214 /* Otherwise, we don't know. */
2222 /* Debugging dumps. */
2224 void dump_value_range (FILE *, value_range_t
*);
2225 void debug_value_range (value_range_t
*);
2226 void dump_all_value_ranges (FILE *);
2227 void debug_all_value_ranges (void);
2228 void dump_vr_equiv (FILE *, bitmap
);
2229 void debug_vr_equiv (bitmap
);
2232 /* Dump value range VR to FILE. */
2235 dump_value_range (FILE *file
, value_range_t
*vr
)
2238 fprintf (file
, "[]");
2239 else if (vr
->type
== VR_UNDEFINED
)
2240 fprintf (file
, "UNDEFINED");
2241 else if (vr
->type
== VR_RANGE
|| vr
->type
== VR_ANTI_RANGE
)
2243 tree type
= TREE_TYPE (vr
->min
);
2245 fprintf (file
, "%s[", (vr
->type
== VR_ANTI_RANGE
) ? "~" : "");
2247 if (INTEGRAL_TYPE_P (type
)
2248 && !TYPE_UNSIGNED (type
)
2249 && vr
->min
== TYPE_MIN_VALUE (type
))
2250 fprintf (file
, "-INF");
2252 print_generic_expr (file
, vr
->min
, 0);
2254 fprintf (file
, ", ");
2256 if (INTEGRAL_TYPE_P (type
)
2257 && vr
->max
== TYPE_MAX_VALUE (type
))
2258 fprintf (file
, "+INF");
2260 print_generic_expr (file
, vr
->max
, 0);
2262 fprintf (file
, "]");
2269 fprintf (file
, " EQUIVALENCES: { ");
2271 EXECUTE_IF_SET_IN_BITMAP (vr
->equiv
, 0, i
, bi
)
2273 print_generic_expr (file
, ssa_name (i
), 0);
2274 fprintf (file
, " ");
2278 fprintf (file
, "} (%u elements)", c
);
2281 else if (vr
->type
== VR_VARYING
)
2282 fprintf (file
, "VARYING");
2284 fprintf (file
, "INVALID RANGE");
2288 /* Dump value range VR to stderr. */
2291 debug_value_range (value_range_t
*vr
)
2293 dump_value_range (stderr
, vr
);
2297 /* Dump value ranges of all SSA_NAMEs to FILE. */
2300 dump_all_value_ranges (FILE *file
)
2304 for (i
= 0; i
< num_ssa_names
; i
++)
2308 print_generic_expr (file
, ssa_name (i
), 0);
2309 fprintf (file
, ": ");
2310 dump_value_range (file
, vr_value
[i
]);
2311 fprintf (file
, "\n");
2315 fprintf (file
, "\n");
2319 /* Dump all value ranges to stderr. */
2322 debug_all_value_ranges (void)
2324 dump_all_value_ranges (stderr
);
2328 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
2329 create a new SSA name N and return the assertion assignment
2330 'V = ASSERT_EXPR <V, V OP W>'. */
2333 build_assert_expr_for (tree cond
, tree v
)
2337 gcc_assert (TREE_CODE (v
) == SSA_NAME
);
2338 n
= duplicate_ssa_name (v
, NULL_TREE
);
2340 if (COMPARISON_CLASS_P (cond
))
2342 tree a
= build2 (ASSERT_EXPR
, TREE_TYPE (v
), v
, cond
);
2343 assertion
= build2 (MODIFY_EXPR
, TREE_TYPE (v
), n
, a
);
2345 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
)
2347 /* Given !V, build the assignment N = false. */
2348 tree op0
= TREE_OPERAND (cond
, 0);
2349 gcc_assert (op0
== v
);
2350 assertion
= build2 (MODIFY_EXPR
, TREE_TYPE (v
), n
, boolean_false_node
);
2352 else if (TREE_CODE (cond
) == SSA_NAME
)
2354 /* Given V, build the assignment N = true. */
2355 gcc_assert (v
== cond
);
2356 assertion
= build2 (MODIFY_EXPR
, TREE_TYPE (v
), n
, boolean_true_node
);
2361 SSA_NAME_DEF_STMT (n
) = assertion
;
2363 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
2364 operand of the ASSERT_EXPR. Register the new name and the old one
2365 in the replacement table so that we can fix the SSA web after
2366 adding all the ASSERT_EXPRs. */
2367 register_new_name_mapping (n
, v
);
2373 /* Return false if EXPR is a predicate expression involving floating
2377 fp_predicate (tree expr
)
2379 return (COMPARISON_CLASS_P (expr
)
2380 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr
, 0))));
2384 /* If the range of values taken by OP can be inferred after STMT executes,
2385 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2386 describes the inferred range. Return true if a range could be
2390 infer_value_range (tree stmt
, tree op
, enum tree_code
*comp_code_p
, tree
*val_p
)
2393 *comp_code_p
= ERROR_MARK
;
2395 /* Do not attempt to infer anything in names that flow through
2397 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op
))
2400 /* Similarly, don't infer anything from statements that may throw
2402 if (tree_could_throw_p (stmt
))
2405 /* If STMT is the last statement of a basic block with no
2406 successors, there is no point inferring anything about any of its
2407 operands. We would not be able to find a proper insertion point
2408 for the assertion, anyway. */
2409 if (stmt_ends_bb_p (stmt
) && EDGE_COUNT (bb_for_stmt (stmt
)->succs
) == 0)
2412 if (POINTER_TYPE_P (TREE_TYPE (op
)))
2415 unsigned num_uses
, num_derefs
;
2417 count_uses_and_derefs (op
, stmt
, &num_uses
, &num_derefs
, &is_store
);
2418 if (num_derefs
> 0 && flag_delete_null_pointer_checks
)
2420 /* We can only assume that a pointer dereference will yield
2421 non-NULL if -fdelete-null-pointer-checks is enabled. */
2422 *val_p
= build_int_cst (TREE_TYPE (op
), 0);
2423 *comp_code_p
= NE_EXPR
;
2432 void dump_asserts_for (FILE *, tree
);
2433 void debug_asserts_for (tree
);
2434 void dump_all_asserts (FILE *);
2435 void debug_all_asserts (void);
2437 /* Dump all the registered assertions for NAME to FILE. */
2440 dump_asserts_for (FILE *file
, tree name
)
2444 fprintf (file
, "Assertions to be inserted for ");
2445 print_generic_expr (file
, name
, 0);
2446 fprintf (file
, "\n");
2448 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
2451 fprintf (file
, "\t");
2452 print_generic_expr (file
, bsi_stmt (loc
->si
), 0);
2453 fprintf (file
, "\n\tBB #%d", loc
->bb
->index
);
2456 fprintf (file
, "\n\tEDGE %d->%d", loc
->e
->src
->index
,
2457 loc
->e
->dest
->index
);
2458 dump_edge_info (file
, loc
->e
, 0);
2460 fprintf (file
, "\n\tPREDICATE: ");
2461 print_generic_expr (file
, name
, 0);
2462 fprintf (file
, " %s ", tree_code_name
[(int)loc
->comp_code
]);
2463 print_generic_expr (file
, loc
->val
, 0);
2464 fprintf (file
, "\n\n");
2468 fprintf (file
, "\n");
2472 /* Dump all the registered assertions for NAME to stderr. */
2475 debug_asserts_for (tree name
)
2477 dump_asserts_for (stderr
, name
);
2481 /* Dump all the registered assertions for all the names to FILE. */
2484 dump_all_asserts (FILE *file
)
2489 fprintf (file
, "\nASSERT_EXPRs to be inserted\n\n");
2490 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
2491 dump_asserts_for (file
, ssa_name (i
));
2492 fprintf (file
, "\n");
2496 /* Dump all the registered assertions for all the names to stderr. */
2499 debug_all_asserts (void)
2501 dump_all_asserts (stderr
);
2505 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2506 'NAME COMP_CODE VAL' at a location that dominates block BB or
2507 E->DEST, then register this location as a possible insertion point
2508 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2510 BB, E and SI provide the exact insertion point for the new
2511 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2512 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2513 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2514 must not be NULL. */
2517 register_new_assert_for (tree name
,
2518 enum tree_code comp_code
,
2522 block_stmt_iterator si
)
2524 assert_locus_t n
, loc
, last_loc
;
2526 basic_block dest_bb
;
2528 #if defined ENABLE_CHECKING
2529 gcc_assert (bb
== NULL
|| e
== NULL
);
2532 gcc_assert (TREE_CODE (bsi_stmt (si
)) != COND_EXPR
2533 && TREE_CODE (bsi_stmt (si
)) != SWITCH_EXPR
);
2536 /* The new assertion A will be inserted at BB or E. We need to
2537 determine if the new location is dominated by a previously
2538 registered location for A. If we are doing an edge insertion,
2539 assume that A will be inserted at E->DEST. Note that this is not
2542 If E is a critical edge, it will be split. But even if E is
2543 split, the new block will dominate the same set of blocks that
2546 The reverse, however, is not true, blocks dominated by E->DEST
2547 will not be dominated by the new block created to split E. So,
2548 if the insertion location is on a critical edge, we will not use
2549 the new location to move another assertion previously registered
2550 at a block dominated by E->DEST. */
2551 dest_bb
= (bb
) ? bb
: e
->dest
;
2553 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2554 VAL at a block dominating DEST_BB, then we don't need to insert a new
2555 one. Similarly, if the same assertion already exists at a block
2556 dominated by DEST_BB and the new location is not on a critical
2557 edge, then update the existing location for the assertion (i.e.,
2558 move the assertion up in the dominance tree).
2560 Note, this is implemented as a simple linked list because there
2561 should not be more than a handful of assertions registered per
2562 name. If this becomes a performance problem, a table hashed by
2563 COMP_CODE and VAL could be implemented. */
2564 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
2569 if (loc
->comp_code
== comp_code
2571 || operand_equal_p (loc
->val
, val
, 0)))
2573 /* If the assertion NAME COMP_CODE VAL has already been
2574 registered at a basic block that dominates DEST_BB, then
2575 we don't need to insert the same assertion again. Note
2576 that we don't check strict dominance here to avoid
2577 replicating the same assertion inside the same basic
2578 block more than once (e.g., when a pointer is
2579 dereferenced several times inside a block).
2581 An exception to this rule are edge insertions. If the
2582 new assertion is to be inserted on edge E, then it will
2583 dominate all the other insertions that we may want to
2584 insert in DEST_BB. So, if we are doing an edge
2585 insertion, don't do this dominance check. */
2587 && dominated_by_p (CDI_DOMINATORS
, dest_bb
, loc
->bb
))
2590 /* Otherwise, if E is not a critical edge and DEST_BB
2591 dominates the existing location for the assertion, move
2592 the assertion up in the dominance tree by updating its
2593 location information. */
2594 if ((e
== NULL
|| !EDGE_CRITICAL_P (e
))
2595 && dominated_by_p (CDI_DOMINATORS
, loc
->bb
, dest_bb
))
2604 /* Update the last node of the list and move to the next one. */
2609 /* If we didn't find an assertion already registered for
2610 NAME COMP_CODE VAL, add a new one at the end of the list of
2611 assertions associated with NAME. */
2612 n
= XNEW (struct assert_locus_d
);
2616 n
->comp_code
= comp_code
;
2623 asserts_for
[SSA_NAME_VERSION (name
)] = n
;
2625 bitmap_set_bit (need_assert_for
, SSA_NAME_VERSION (name
));
2629 /* Try to register an edge assertion for SSA name NAME on edge E for
2630 the conditional jump pointed to by SI. Return true if an assertion
2631 for NAME could be registered. */
2634 register_edge_assert_for (tree name
, edge e
, block_stmt_iterator si
)
2637 enum tree_code comp_code
;
2639 stmt
= bsi_stmt (si
);
2641 /* Do not attempt to infer anything in names that flow through
2643 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name
))
2646 /* If NAME was not found in the sub-graph reachable from E, then
2647 there's nothing to do. */
2648 if (!TEST_BIT (found_in_subgraph
, SSA_NAME_VERSION (name
)))
2651 /* We found a use of NAME in the sub-graph rooted at E->DEST.
2652 Register an assertion for NAME according to the value that NAME
2654 if (TREE_CODE (stmt
) == COND_EXPR
)
2656 /* If BB ends in a COND_EXPR then NAME then we should insert
2657 the original predicate on EDGE_TRUE_VALUE and the
2658 opposite predicate on EDGE_FALSE_VALUE. */
2659 tree cond
= COND_EXPR_COND (stmt
);
2660 bool is_else_edge
= (e
->flags
& EDGE_FALSE_VALUE
) != 0;
2662 /* Predicates may be a single SSA name or NAME OP VAL. */
2665 /* If the predicate is a name, it must be NAME, in which
2666 case we create the predicate NAME == true or
2667 NAME == false accordingly. */
2668 comp_code
= EQ_EXPR
;
2669 val
= (is_else_edge
) ? boolean_false_node
: boolean_true_node
;
2673 /* Otherwise, we have a comparison of the form NAME COMP VAL
2674 or VAL COMP NAME. */
2675 if (name
== TREE_OPERAND (cond
, 1))
2677 /* If the predicate is of the form VAL COMP NAME, flip
2678 COMP around because we need to register NAME as the
2679 first operand in the predicate. */
2680 comp_code
= swap_tree_comparison (TREE_CODE (cond
));
2681 val
= TREE_OPERAND (cond
, 0);
2685 /* The comparison is of the form NAME COMP VAL, so the
2686 comparison code remains unchanged. */
2687 comp_code
= TREE_CODE (cond
);
2688 val
= TREE_OPERAND (cond
, 1);
2691 /* If we are inserting the assertion on the ELSE edge, we
2692 need to invert the sign comparison. */
2694 comp_code
= invert_tree_comparison (comp_code
, 0);
2696 /* Do not register always-false predicates. FIXME, this
2697 works around a limitation in fold() when dealing with
2698 enumerations. Given 'enum { N1, N2 } x;', fold will not
2699 fold 'if (x > N2)' to 'if (0)'. */
2700 if ((comp_code
== GT_EXPR
|| comp_code
== LT_EXPR
)
2701 && (INTEGRAL_TYPE_P (TREE_TYPE (val
))
2702 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (val
))))
2704 tree min
= TYPE_MIN_VALUE (TREE_TYPE (val
));
2705 tree max
= TYPE_MAX_VALUE (TREE_TYPE (val
));
2707 if (comp_code
== GT_EXPR
&& compare_values (val
, max
) == 0)
2710 if (comp_code
== LT_EXPR
&& compare_values (val
, min
) == 0)
2717 /* FIXME. Handle SWITCH_EXPR. */
2721 register_new_assert_for (name
, comp_code
, val
, NULL
, e
, si
);
2726 static bool find_assert_locations (basic_block bb
);
2728 /* Determine whether the outgoing edges of BB should receive an
2729 ASSERT_EXPR for each of the operands of BB's last statement. The
2730 last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2732 If any of the sub-graphs rooted at BB have an interesting use of
2733 the predicate operands, an assert location node is added to the
2734 list of assertions for the corresponding operands. */
2737 find_conditional_asserts (basic_block bb
)
2740 block_stmt_iterator last_si
;
2746 need_assert
= false;
2747 last_si
= bsi_last (bb
);
2748 last
= bsi_stmt (last_si
);
2750 /* Look for uses of the operands in each of the sub-graphs
2751 rooted at BB. We need to check each of the outgoing edges
2752 separately, so that we know what kind of ASSERT_EXPR to
2754 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2759 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
2760 Otherwise, when we finish traversing each of the sub-graphs, we
2761 won't know whether the variables were found in the sub-graphs or
2762 if they had been found in a block upstream from BB. */
2763 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
2764 RESET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
2766 /* Traverse the strictly dominated sub-graph rooted at E->DEST
2767 to determine if any of the operands in the conditional
2768 predicate are used. */
2770 need_assert
|= find_assert_locations (e
->dest
);
2772 /* Register the necessary assertions for each operand in the
2773 conditional predicate. */
2774 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
2775 need_assert
|= register_edge_assert_for (op
, e
, last_si
);
2778 /* Finally, indicate that we have found the operands in the
2780 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
2781 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
2787 /* Traverse all the statements in block BB looking for statements that
2788 may generate useful assertions for the SSA names in their operand.
2789 If a statement produces a useful assertion A for name N_i, then the
2790 list of assertions already generated for N_i is scanned to
2791 determine if A is actually needed.
2793 If N_i already had the assertion A at a location dominating the
2794 current location, then nothing needs to be done. Otherwise, the
2795 new location for A is recorded instead.
2797 1- For every statement S in BB, all the variables used by S are
2798 added to bitmap FOUND_IN_SUBGRAPH.
2800 2- If statement S uses an operand N in a way that exposes a known
2801 value range for N, then if N was not already generated by an
2802 ASSERT_EXPR, create a new assert location for N. For instance,
2803 if N is a pointer and the statement dereferences it, we can
2804 assume that N is not NULL.
2806 3- COND_EXPRs are a special case of #2. We can derive range
2807 information from the predicate but need to insert different
2808 ASSERT_EXPRs for each of the sub-graphs rooted at the
2809 conditional block. If the last statement of BB is a conditional
2810 expression of the form 'X op Y', then
2812 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
2814 b) If the conditional is the only entry point to the sub-graph
2815 corresponding to the THEN_CLAUSE, recurse into it. On
2816 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
2817 an ASSERT_EXPR is added for the corresponding variable.
2819 c) Repeat step (b) on the ELSE_CLAUSE.
2821 d) Mark X and Y in FOUND_IN_SUBGRAPH.
2830 In this case, an assertion on the THEN clause is useful to
2831 determine that 'a' is always 9 on that edge. However, an assertion
2832 on the ELSE clause would be unnecessary.
2834 4- If BB does not end in a conditional expression, then we recurse
2835 into BB's dominator children.
2837 At the end of the recursive traversal, every SSA name will have a
2838 list of locations where ASSERT_EXPRs should be added. When a new
2839 location for name N is found, it is registered by calling
2840 register_new_assert_for. That function keeps track of all the
2841 registered assertions to prevent adding unnecessary assertions.
2842 For instance, if a pointer P_4 is dereferenced more than once in a
2843 dominator tree, only the location dominating all the dereference of
2844 P_4 will receive an ASSERT_EXPR.
2846 If this function returns true, then it means that there are names
2847 for which we need to generate ASSERT_EXPRs. Those assertions are
2848 inserted by process_assert_insertions.
2850 TODO. Handle SWITCH_EXPR. */
2853 find_assert_locations (basic_block bb
)
2855 block_stmt_iterator si
;
2860 if (TEST_BIT (blocks_visited
, bb
->index
))
2863 SET_BIT (blocks_visited
, bb
->index
);
2865 need_assert
= false;
2867 /* Traverse all PHI nodes in BB marking used operands. */
2868 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
2870 use_operand_p arg_p
;
2873 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_USE
)
2875 tree arg
= USE_FROM_PTR (arg_p
);
2876 if (TREE_CODE (arg
) == SSA_NAME
)
2878 gcc_assert (is_gimple_reg (PHI_RESULT (phi
)));
2879 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (arg
));
2884 /* Traverse all the statements in BB marking used names and looking
2885 for statements that may infer assertions for their used operands. */
2887 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
2892 stmt
= bsi_stmt (si
);
2894 /* See if we can derive an assertion for any of STMT's operands. */
2895 FOR_EACH_SSA_TREE_OPERAND (op
, stmt
, i
, SSA_OP_USE
)
2898 enum tree_code comp_code
;
2900 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
2901 the sub-graph of a conditional block, when we return from
2902 this recursive walk, our parent will use the
2903 FOUND_IN_SUBGRAPH bitset to determine if one of the
2904 operands it was looking for was present in the sub-graph. */
2905 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
2907 /* If OP is used only once, namely in this STMT, don't
2908 bother creating an ASSERT_EXPR for it. Such an
2909 ASSERT_EXPR would do nothing but increase compile time.
2910 Experiments show that with this simple check, we can save
2911 more than 20% of ASSERT_EXPRs. */
2912 if (has_single_use (op
))
2915 /* If OP is used in such a way that we can infer a value
2916 range for it, and we don't find a previous assertion for
2917 it, create a new assertion location node for OP. */
2918 if (infer_value_range (stmt
, op
, &comp_code
, &value
))
2920 register_new_assert_for (op
, comp_code
, value
, bb
, NULL
, si
);
2925 /* Remember the last statement of the block. */
2929 /* If BB's last statement is a conditional expression
2930 involving integer operands, recurse into each of the sub-graphs
2931 rooted at BB to determine if we need to add ASSERT_EXPRs. */
2933 && TREE_CODE (last
) == COND_EXPR
2934 && !fp_predicate (COND_EXPR_COND (last
))
2935 && !ZERO_SSA_OPERANDS (last
, SSA_OP_USE
))
2936 need_assert
|= find_conditional_asserts (bb
);
2938 /* Recurse into the dominator children of BB. */
2939 for (son
= first_dom_son (CDI_DOMINATORS
, bb
);
2941 son
= next_dom_son (CDI_DOMINATORS
, son
))
2942 need_assert
|= find_assert_locations (son
);
2948 /* Create an ASSERT_EXPR for NAME and insert it in the location
2949 indicated by LOC. Return true if we made any edge insertions. */
2952 process_assert_insertions_for (tree name
, assert_locus_t loc
)
2954 /* Build the comparison expression NAME_i COMP_CODE VAL. */
2955 tree stmt
, cond
, assert_expr
;
2959 cond
= build2 (loc
->comp_code
, boolean_type_node
, name
, loc
->val
);
2960 assert_expr
= build_assert_expr_for (cond
, name
);
2964 /* We have been asked to insert the assertion on an edge. This
2965 is used only by COND_EXPR and SWITCH_EXPR assertions. */
2966 #if defined ENABLE_CHECKING
2967 gcc_assert (TREE_CODE (bsi_stmt (loc
->si
)) == COND_EXPR
2968 || TREE_CODE (bsi_stmt (loc
->si
)) == SWITCH_EXPR
);
2971 bsi_insert_on_edge (loc
->e
, assert_expr
);
2975 /* Otherwise, we can insert right after LOC->SI iff the
2976 statement must not be the last statement in the block. */
2977 stmt
= bsi_stmt (loc
->si
);
2978 if (!stmt_ends_bb_p (stmt
))
2980 bsi_insert_after (&loc
->si
, assert_expr
, BSI_SAME_STMT
);
2984 /* If STMT must be the last statement in BB, we can only insert new
2985 assertions on the non-abnormal edge out of BB. Note that since
2986 STMT is not control flow, there may only be one non-abnormal edge
2988 FOR_EACH_EDGE (e
, ei
, loc
->bb
->succs
)
2989 if (!(e
->flags
& EDGE_ABNORMAL
))
2991 bsi_insert_on_edge (e
, assert_expr
);
2999 /* Process all the insertions registered for every name N_i registered
3000 in NEED_ASSERT_FOR. The list of assertions to be inserted are
3001 found in ASSERTS_FOR[i]. */
3004 process_assert_insertions (void)
3008 bool update_edges_p
= false;
3009 int num_asserts
= 0;
3011 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3012 dump_all_asserts (dump_file
);
3014 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
3016 assert_locus_t loc
= asserts_for
[i
];
3021 assert_locus_t next
= loc
->next
;
3022 update_edges_p
|= process_assert_insertions_for (ssa_name (i
), loc
);
3030 bsi_commit_edge_inserts ();
3032 if (dump_file
&& (dump_flags
& TDF_STATS
))
3033 fprintf (dump_file
, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
3038 /* Traverse the flowgraph looking for conditional jumps to insert range
3039 expressions. These range expressions are meant to provide information
3040 to optimizations that need to reason in terms of value ranges. They
3041 will not be expanded into RTL. For instance, given:
3050 this pass will transform the code into:
3056 x = ASSERT_EXPR <x, x < y>
3061 y = ASSERT_EXPR <y, x <= y>
3065 The idea is that once copy and constant propagation have run, other
3066 optimizations will be able to determine what ranges of values can 'x'
3067 take in different paths of the code, simply by checking the reaching
3068 definition of 'x'. */
3071 insert_range_assertions (void)
3077 found_in_subgraph
= sbitmap_alloc (num_ssa_names
);
3078 sbitmap_zero (found_in_subgraph
);
3080 blocks_visited
= sbitmap_alloc (last_basic_block
);
3081 sbitmap_zero (blocks_visited
);
3083 need_assert_for
= BITMAP_ALLOC (NULL
);
3084 asserts_for
= XNEWVEC (assert_locus_t
, num_ssa_names
);
3085 memset (asserts_for
, 0, num_ssa_names
* sizeof (assert_locus_t
));
3087 calculate_dominance_info (CDI_DOMINATORS
);
3089 update_ssa_p
= false;
3090 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
3091 if (find_assert_locations (e
->dest
))
3092 update_ssa_p
= true;
3096 process_assert_insertions ();
3097 update_ssa (TODO_update_ssa_no_phi
);
3100 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3102 fprintf (dump_file
, "\nSSA form after inserting ASSERT_EXPRs\n");
3103 dump_function_to_file (current_function_decl
, dump_file
, dump_flags
);
3106 sbitmap_free (found_in_subgraph
);
3108 BITMAP_FREE (need_assert_for
);
3112 /* Convert range assertion expressions into the implied copies and
3113 copy propagate away the copies. Doing the trivial copy propagation
3114 here avoids the need to run the full copy propagation pass after
3117 FIXME, this will eventually lead to copy propagation removing the
3118 names that had useful range information attached to them. For
3119 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
3120 then N_i will have the range [3, +INF].
3122 However, by converting the assertion into the implied copy
3123 operation N_i = N_j, we will then copy-propagate N_j into the uses
3124 of N_i and lose the range information. We may want to hold on to
3125 ASSERT_EXPRs a little while longer as the ranges could be used in
3126 things like jump threading.
3128 The problem with keeping ASSERT_EXPRs around is that passes after
3129 VRP need to handle them appropriately.
3131 Another approach would be to make the range information a first
3132 class property of the SSA_NAME so that it can be queried from
3133 any pass. This is made somewhat more complex by the need for
3134 multiple ranges to be associated with one SSA_NAME. */
3137 remove_range_assertions (void)
3140 block_stmt_iterator si
;
3142 /* Note that the BSI iterator bump happens at the bottom of the
3143 loop and no bump is necessary if we're removing the statement
3144 referenced by the current BSI. */
3146 for (si
= bsi_start (bb
); !bsi_end_p (si
);)
3148 tree stmt
= bsi_stmt (si
);
3150 if (TREE_CODE (stmt
) == MODIFY_EXPR
3151 && TREE_CODE (TREE_OPERAND (stmt
, 1)) == ASSERT_EXPR
)
3153 tree rhs
= TREE_OPERAND (stmt
, 1);
3154 tree cond
= fold (ASSERT_EXPR_COND (rhs
));
3155 use_operand_p use_p
;
3156 imm_use_iterator iter
;
3158 gcc_assert (cond
!= boolean_false_node
);
3159 TREE_OPERAND (stmt
, 1) = ASSERT_EXPR_VAR (rhs
);
3162 /* The statement is now a copy. Propagate the RHS into
3163 every use of the LHS. */
3164 FOR_EACH_IMM_USE_SAFE (use_p
, iter
, TREE_OPERAND (stmt
, 0))
3166 SET_USE (use_p
, ASSERT_EXPR_VAR (rhs
));
3167 update_stmt (USE_STMT (use_p
));
3170 /* And finally, remove the copy, it is not needed. */
3171 bsi_remove (&si
, true);
3177 sbitmap_free (blocks_visited
);
3181 /* Return true if STMT is interesting for VRP. */
3184 stmt_interesting_for_vrp (tree stmt
)
3186 if (TREE_CODE (stmt
) == PHI_NODE
3187 && is_gimple_reg (PHI_RESULT (stmt
))
3188 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))
3189 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))))
3191 else if (TREE_CODE (stmt
) == MODIFY_EXPR
)
3193 tree lhs
= TREE_OPERAND (stmt
, 0);
3195 if (TREE_CODE (lhs
) == SSA_NAME
3196 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
3197 || POINTER_TYPE_P (TREE_TYPE (lhs
)))
3198 && ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
3201 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
3208 /* Initialize local data structures for VRP. */
3211 vrp_initialize (void)
3215 vr_value
= XNEWVEC (value_range_t
*, num_ssa_names
);
3216 memset (vr_value
, 0, num_ssa_names
* sizeof (value_range_t
*));
3220 block_stmt_iterator si
;
3223 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3225 if (!stmt_interesting_for_vrp (phi
))
3227 tree lhs
= PHI_RESULT (phi
);
3228 set_value_range_to_varying (get_value_range (lhs
));
3229 DONT_SIMULATE_AGAIN (phi
) = true;
3232 DONT_SIMULATE_AGAIN (phi
) = false;
3235 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
3237 tree stmt
= bsi_stmt (si
);
3239 if (!stmt_interesting_for_vrp (stmt
))
3243 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, i
, SSA_OP_DEF
)
3244 set_value_range_to_varying (get_value_range (def
));
3245 DONT_SIMULATE_AGAIN (stmt
) = true;
3249 DONT_SIMULATE_AGAIN (stmt
) = false;
3256 /* Visit assignment STMT. If it produces an interesting range, record
3257 the SSA name in *OUTPUT_P. */
3259 static enum ssa_prop_result
3260 vrp_visit_assignment (tree stmt
, tree
*output_p
)
3265 lhs
= TREE_OPERAND (stmt
, 0);
3266 rhs
= TREE_OPERAND (stmt
, 1);
3268 /* We only keep track of ranges in integral and pointer types. */
3269 if (TREE_CODE (lhs
) == SSA_NAME
3270 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
3271 || POINTER_TYPE_P (TREE_TYPE (lhs
))))
3274 value_range_t new_vr
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
3276 extract_range_from_expr (&new_vr
, rhs
);
3278 /* If STMT is inside a loop, we may be able to know something
3279 else about the range of LHS by examining scalar evolution
3281 if (cfg_loops
&& (l
= loop_containing_stmt (stmt
)))
3282 adjust_range_with_scev (&new_vr
, l
, stmt
, lhs
);
3284 if (update_value_range (lhs
, &new_vr
))
3288 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3290 fprintf (dump_file
, "Found new range for ");
3291 print_generic_expr (dump_file
, lhs
, 0);
3292 fprintf (dump_file
, ": ");
3293 dump_value_range (dump_file
, &new_vr
);
3294 fprintf (dump_file
, "\n\n");
3297 if (new_vr
.type
== VR_VARYING
)
3298 return SSA_PROP_VARYING
;
3300 return SSA_PROP_INTERESTING
;
3303 return SSA_PROP_NOT_INTERESTING
;
3306 /* Every other statement produces no useful ranges. */
3307 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
3308 set_value_range_to_varying (get_value_range (def
));
3310 return SSA_PROP_VARYING
;
3314 /* Compare all the value ranges for names equivalent to VAR with VAL
3315 using comparison code COMP. Return the same value returned by
3316 compare_range_with_value. */
3319 compare_name_with_value (enum tree_code comp
, tree var
, tree val
)
3326 t
= retval
= NULL_TREE
;
3328 /* Get the set of equivalences for VAR. */
3329 e
= get_value_range (var
)->equiv
;
3331 /* Add VAR to its own set of equivalences so that VAR's value range
3332 is processed by this loop (otherwise, we would have to replicate
3333 the body of the loop just to check VAR's value range). */
3334 bitmap_set_bit (e
, SSA_NAME_VERSION (var
));
3336 EXECUTE_IF_SET_IN_BITMAP (e
, 0, i
, bi
)
3338 value_range_t equiv_vr
= *(vr_value
[i
]);
3340 /* If name N_i does not have a valid range, use N_i as its own
3341 range. This allows us to compare against names that may
3342 have N_i in their ranges. */
3343 if (equiv_vr
.type
== VR_VARYING
|| equiv_vr
.type
== VR_UNDEFINED
)
3345 equiv_vr
.type
= VR_RANGE
;
3346 equiv_vr
.min
= ssa_name (i
);
3347 equiv_vr
.max
= ssa_name (i
);
3350 t
= compare_range_with_value (comp
, &equiv_vr
, val
);
3353 /* All the ranges should compare the same against VAL. */
3354 gcc_assert (retval
== NULL
|| t
== retval
);
3359 /* Remove VAR from its own equivalence set. */
3360 bitmap_clear_bit (e
, SSA_NAME_VERSION (var
));
3365 /* We couldn't find a non-NULL value for the predicate. */
3370 /* Given a comparison code COMP and names N1 and N2, compare all the
3371 ranges equivalent to N1 against all the ranges equivalent to N2
3372 to determine the value of N1 COMP N2. Return the same value
3373 returned by compare_ranges. */
3376 compare_names (enum tree_code comp
, tree n1
, tree n2
)
3380 bitmap_iterator bi1
, bi2
;
3383 /* Compare the ranges of every name equivalent to N1 against the
3384 ranges of every name equivalent to N2. */
3385 e1
= get_value_range (n1
)->equiv
;
3386 e2
= get_value_range (n2
)->equiv
;
3388 /* Add N1 and N2 to their own set of equivalences to avoid
3389 duplicating the body of the loop just to check N1 and N2
3391 bitmap_set_bit (e1
, SSA_NAME_VERSION (n1
));
3392 bitmap_set_bit (e2
, SSA_NAME_VERSION (n2
));
3394 /* If the equivalence sets have a common intersection, then the two
3395 names can be compared without checking their ranges. */
3396 if (bitmap_intersect_p (e1
, e2
))
3398 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3399 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3401 return (comp
== EQ_EXPR
|| comp
== GE_EXPR
|| comp
== LE_EXPR
)
3403 : boolean_false_node
;
3406 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3407 N2 to their own set of equivalences to avoid duplicating the body
3408 of the loop just to check N1 and N2 ranges. */
3409 EXECUTE_IF_SET_IN_BITMAP (e1
, 0, i1
, bi1
)
3411 value_range_t vr1
= *(vr_value
[i1
]);
3413 /* If the range is VARYING or UNDEFINED, use the name itself. */
3414 if (vr1
.type
== VR_VARYING
|| vr1
.type
== VR_UNDEFINED
)
3416 vr1
.type
= VR_RANGE
;
3417 vr1
.min
= ssa_name (i1
);
3418 vr1
.max
= ssa_name (i1
);
3421 t
= retval
= NULL_TREE
;
3422 EXECUTE_IF_SET_IN_BITMAP (e2
, 0, i2
, bi2
)
3424 value_range_t vr2
= *(vr_value
[i2
]);
3426 if (vr2
.type
== VR_VARYING
|| vr2
.type
== VR_UNDEFINED
)
3428 vr2
.type
= VR_RANGE
;
3429 vr2
.min
= ssa_name (i2
);
3430 vr2
.max
= ssa_name (i2
);
3433 t
= compare_ranges (comp
, &vr1
, &vr2
);
3436 /* All the ranges in the equivalent sets should compare
3438 gcc_assert (retval
== NULL
|| t
== retval
);
3445 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3446 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3451 /* None of the equivalent ranges are useful in computing this
3453 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3454 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3459 /* Given a conditional predicate COND, try to determine if COND yields
3460 true or false based on the value ranges of its operands. Return
3461 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3462 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3463 NULL if the conditional cannot be evaluated at compile time.
3465 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3466 the operands in COND are used when trying to compute its value.
3467 This is only used during final substitution. During propagation,
3468 we only check the range of each variable and not its equivalents. */
3471 vrp_evaluate_conditional (tree cond
, bool use_equiv_p
)
3473 gcc_assert (TREE_CODE (cond
) == SSA_NAME
3474 || TREE_CODE_CLASS (TREE_CODE (cond
)) == tcc_comparison
);
3476 if (TREE_CODE (cond
) == SSA_NAME
)
3482 retval
= compare_name_with_value (NE_EXPR
, cond
, boolean_false_node
);
3485 value_range_t
*vr
= get_value_range (cond
);
3486 retval
= compare_range_with_value (NE_EXPR
, vr
, boolean_false_node
);
3489 /* If COND has a known boolean range, return it. */
3493 /* Otherwise, if COND has a symbolic range of exactly one value,
3495 vr
= get_value_range (cond
);
3496 if (vr
->type
== VR_RANGE
&& vr
->min
== vr
->max
)
3501 tree op0
= TREE_OPERAND (cond
, 0);
3502 tree op1
= TREE_OPERAND (cond
, 1);
3504 /* We only deal with integral and pointer types. */
3505 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
3506 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
3511 if (TREE_CODE (op0
) == SSA_NAME
&& TREE_CODE (op1
) == SSA_NAME
)
3512 return compare_names (TREE_CODE (cond
), op0
, op1
);
3513 else if (TREE_CODE (op0
) == SSA_NAME
)
3514 return compare_name_with_value (TREE_CODE (cond
), op0
, op1
);
3515 else if (TREE_CODE (op1
) == SSA_NAME
)
3516 return compare_name_with_value (
3517 swap_tree_comparison (TREE_CODE (cond
)), op1
, op0
);
3521 value_range_t
*vr0
, *vr1
;
3523 vr0
= (TREE_CODE (op0
) == SSA_NAME
) ? get_value_range (op0
) : NULL
;
3524 vr1
= (TREE_CODE (op1
) == SSA_NAME
) ? get_value_range (op1
) : NULL
;
3527 return compare_ranges (TREE_CODE (cond
), vr0
, vr1
);
3528 else if (vr0
&& vr1
== NULL
)
3529 return compare_range_with_value (TREE_CODE (cond
), vr0
, op1
);
3530 else if (vr0
== NULL
&& vr1
)
3531 return compare_range_with_value (
3532 swap_tree_comparison (TREE_CODE (cond
)), vr1
, op0
);
3536 /* Anything else cannot be computed statically. */
3541 /* Visit conditional statement STMT. If we can determine which edge
3542 will be taken out of STMT's basic block, record it in
3543 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3544 SSA_PROP_VARYING. */
3546 static enum ssa_prop_result
3547 vrp_visit_cond_stmt (tree stmt
, edge
*taken_edge_p
)
3551 *taken_edge_p
= NULL
;
3553 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3554 add ASSERT_EXPRs for them. */
3555 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
3556 return SSA_PROP_VARYING
;
3558 cond
= COND_EXPR_COND (stmt
);
3560 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3565 fprintf (dump_file
, "\nVisiting conditional with predicate: ");
3566 print_generic_expr (dump_file
, cond
, 0);
3567 fprintf (dump_file
, "\nWith known ranges\n");
3569 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, i
, SSA_OP_USE
)
3571 fprintf (dump_file
, "\t");
3572 print_generic_expr (dump_file
, use
, 0);
3573 fprintf (dump_file
, ": ");
3574 dump_value_range (dump_file
, vr_value
[SSA_NAME_VERSION (use
)]);
3577 fprintf (dump_file
, "\n");
3580 /* Compute the value of the predicate COND by checking the known
3581 ranges of each of its operands.
3583 Note that we cannot evaluate all the equivalent ranges here
3584 because those ranges may not yet be final and with the current
3585 propagation strategy, we cannot determine when the value ranges
3586 of the names in the equivalence set have changed.
3588 For instance, given the following code fragment
3592 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3596 Assume that on the first visit to i_14, i_5 has the temporary
3597 range [8, 8] because the second argument to the PHI function is
3598 not yet executable. We derive the range ~[0, 0] for i_14 and the
3599 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3600 the first time, since i_14 is equivalent to the range [8, 8], we
3601 determine that the predicate is always false.
3603 On the next round of propagation, i_13 is determined to be
3604 VARYING, which causes i_5 to drop down to VARYING. So, another
3605 visit to i_14 is scheduled. In this second visit, we compute the
3606 exact same range and equivalence set for i_14, namely ~[0, 0] and
3607 { i_5 }. But we did not have the previous range for i_5
3608 registered, so vrp_visit_assignment thinks that the range for
3609 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3610 is not visited again, which stops propagation from visiting
3611 statements in the THEN clause of that if().
3613 To properly fix this we would need to keep the previous range
3614 value for the names in the equivalence set. This way we would've
3615 discovered that from one visit to the other i_5 changed from
3616 range [8, 8] to VR_VARYING.
3618 However, fixing this apparent limitation may not be worth the
3619 additional checking. Testing on several code bases (GCC, DLV,
3620 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3621 4 more predicates folded in SPEC. */
3622 val
= vrp_evaluate_conditional (cond
, false);
3624 *taken_edge_p
= find_taken_edge (bb_for_stmt (stmt
), val
);
3626 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3628 fprintf (dump_file
, "\nPredicate evaluates to: ");
3629 if (val
== NULL_TREE
)
3630 fprintf (dump_file
, "DON'T KNOW\n");
3632 print_generic_stmt (dump_file
, val
, 0);
3635 return (*taken_edge_p
) ? SSA_PROP_INTERESTING
: SSA_PROP_VARYING
;
3639 /* Evaluate statement STMT. If the statement produces a useful range,
3640 return SSA_PROP_INTERESTING and record the SSA name with the
3641 interesting range into *OUTPUT_P.
3643 If STMT is a conditional branch and we can determine its truth
3644 value, the taken edge is recorded in *TAKEN_EDGE_P.
3646 If STMT produces a varying value, return SSA_PROP_VARYING. */
3648 static enum ssa_prop_result
3649 vrp_visit_stmt (tree stmt
, edge
*taken_edge_p
, tree
*output_p
)
3655 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3657 fprintf (dump_file
, "\nVisiting statement:\n");
3658 print_generic_stmt (dump_file
, stmt
, dump_flags
);
3659 fprintf (dump_file
, "\n");
3662 ann
= stmt_ann (stmt
);
3663 if (TREE_CODE (stmt
) == MODIFY_EXPR
3664 && ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
3665 return vrp_visit_assignment (stmt
, output_p
);
3666 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
3667 return vrp_visit_cond_stmt (stmt
, taken_edge_p
);
3669 /* All other statements produce nothing of interest for VRP, so mark
3670 their outputs varying and prevent further simulation. */
3671 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
3672 set_value_range_to_varying (get_value_range (def
));
3674 return SSA_PROP_VARYING
;
3678 /* Meet operation for value ranges. Given two value ranges VR0 and
3679 VR1, store in VR0 the result of meeting VR0 and VR1.
3681 The meeting rules are as follows:
3683 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
3685 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
3686 union of VR0 and VR1. */
3689 vrp_meet (value_range_t
*vr0
, value_range_t
*vr1
)
3691 if (vr0
->type
== VR_UNDEFINED
)
3693 copy_value_range (vr0
, vr1
);
3697 if (vr1
->type
== VR_UNDEFINED
)
3699 /* Nothing to do. VR0 already has the resulting range. */
3703 if (vr0
->type
== VR_VARYING
)
3705 /* Nothing to do. VR0 already has the resulting range. */
3709 if (vr1
->type
== VR_VARYING
)
3711 set_value_range_to_varying (vr0
);
3715 if (vr0
->type
== VR_RANGE
&& vr1
->type
== VR_RANGE
)
3717 /* If VR0 and VR1 have a non-empty intersection, compute the
3718 union of both ranges. */
3719 if (value_ranges_intersect_p (vr0
, vr1
))
3724 /* The lower limit of the new range is the minimum of the
3725 two ranges. If they cannot be compared, the result is
3727 cmp
= compare_values (vr0
->min
, vr1
->min
);
3728 if (cmp
== 0 || cmp
== 1)
3734 set_value_range_to_varying (vr0
);
3738 /* Similarly, the upper limit of the new range is the
3739 maximum of the two ranges. If they cannot be compared,
3740 the result is VARYING. */
3741 cmp
= compare_values (vr0
->max
, vr1
->max
);
3742 if (cmp
== 0 || cmp
== -1)
3748 set_value_range_to_varying (vr0
);
3752 /* The resulting set of equivalences is the intersection of
3754 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
3755 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
3756 else if (vr0
->equiv
&& !vr1
->equiv
)
3757 bitmap_clear (vr0
->equiv
);
3759 set_value_range (vr0
, vr0
->type
, min
, max
, vr0
->equiv
);
3764 else if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
3766 /* Two anti-ranges meet only if they are both identical. */
3767 if (compare_values (vr0
->min
, vr1
->min
) == 0
3768 && compare_values (vr0
->max
, vr1
->max
) == 0
3769 && compare_values (vr0
->min
, vr0
->max
) == 0)
3771 /* The resulting set of equivalences is the intersection of
3773 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
3774 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
3775 else if (vr0
->equiv
&& !vr1
->equiv
)
3776 bitmap_clear (vr0
->equiv
);
3781 else if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
3783 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
3784 meet only if the ranges have an empty intersection. The
3785 result of the meet operation is the anti-range. */
3786 if (!symbolic_range_p (vr0
)
3787 && !symbolic_range_p (vr1
)
3788 && !value_ranges_intersect_p (vr0
, vr1
))
3790 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
3791 set. We need to compute the intersection of the two
3792 equivalence sets. */
3793 if (vr1
->type
== VR_ANTI_RANGE
)
3794 set_value_range (vr0
, vr1
->type
, vr1
->min
, vr1
->max
, vr0
->equiv
);
3796 /* The resulting set of equivalences is the intersection of
3798 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
3799 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
3800 else if (vr0
->equiv
&& !vr1
->equiv
)
3801 bitmap_clear (vr0
->equiv
);
3812 /* The two range VR0 and VR1 do not meet. Before giving up and
3813 setting the result to VARYING, see if we can at least derive a
3814 useful anti-range. FIXME, all this nonsense about distinguishing
3815 anti-ranges from ranges is necessary because of the odd
3816 semantics of range_includes_zero_p and friends. */
3817 if (!symbolic_range_p (vr0
)
3818 && ((vr0
->type
== VR_RANGE
&& !range_includes_zero_p (vr0
))
3819 || (vr0
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr0
)))
3820 && !symbolic_range_p (vr1
)
3821 && ((vr1
->type
== VR_RANGE
&& !range_includes_zero_p (vr1
))
3822 || (vr1
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr1
))))
3824 set_value_range_to_nonnull (vr0
, TREE_TYPE (vr0
->min
));
3826 /* Since this meet operation did not result from the meeting of
3827 two equivalent names, VR0 cannot have any equivalences. */
3829 bitmap_clear (vr0
->equiv
);
3832 set_value_range_to_varying (vr0
);
3836 /* Visit all arguments for PHI node PHI that flow through executable
3837 edges. If a valid value range can be derived from all the incoming
3838 value ranges, set a new range for the LHS of PHI. */
3840 static enum ssa_prop_result
3841 vrp_visit_phi_node (tree phi
)
3844 tree lhs
= PHI_RESULT (phi
);
3845 value_range_t
*lhs_vr
= get_value_range (lhs
);
3846 value_range_t vr_result
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
3848 copy_value_range (&vr_result
, lhs_vr
);
3850 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3852 fprintf (dump_file
, "\nVisiting PHI node: ");
3853 print_generic_expr (dump_file
, phi
, dump_flags
);
3856 for (i
= 0; i
< PHI_NUM_ARGS (phi
); i
++)
3858 edge e
= PHI_ARG_EDGE (phi
, i
);
3860 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3863 "\n Argument #%d (%d -> %d %sexecutable)\n",
3864 i
, e
->src
->index
, e
->dest
->index
,
3865 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
3868 if (e
->flags
& EDGE_EXECUTABLE
)
3870 tree arg
= PHI_ARG_DEF (phi
, i
);
3871 value_range_t vr_arg
;
3873 if (TREE_CODE (arg
) == SSA_NAME
)
3874 vr_arg
= *(get_value_range (arg
));
3877 vr_arg
.type
= VR_RANGE
;
3880 vr_arg
.equiv
= NULL
;
3883 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3885 fprintf (dump_file
, "\t");
3886 print_generic_expr (dump_file
, arg
, dump_flags
);
3887 fprintf (dump_file
, "\n\tValue: ");
3888 dump_value_range (dump_file
, &vr_arg
);
3889 fprintf (dump_file
, "\n");
3892 vrp_meet (&vr_result
, &vr_arg
);
3894 if (vr_result
.type
== VR_VARYING
)
3899 if (vr_result
.type
== VR_VARYING
)
3902 /* To prevent infinite iterations in the algorithm, derive ranges
3903 when the new value is slightly bigger or smaller than the
3905 if (lhs_vr
->type
== VR_RANGE
&& vr_result
.type
== VR_RANGE
)
3907 if (!POINTER_TYPE_P (TREE_TYPE (lhs
)))
3909 int cmp_min
= compare_values (lhs_vr
->min
, vr_result
.min
);
3910 int cmp_max
= compare_values (lhs_vr
->max
, vr_result
.max
);
3912 /* If the new minimum is smaller or larger than the previous
3913 one, go all the way to -INF. In the first case, to avoid
3914 iterating millions of times to reach -INF, and in the
3915 other case to avoid infinite bouncing between different
3917 if (cmp_min
> 0 || cmp_min
< 0)
3918 vr_result
.min
= TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
));
3920 /* Similarly, if the new maximum is smaller or larger than
3921 the previous one, go all the way to +INF. */
3922 if (cmp_max
< 0 || cmp_max
> 0)
3923 vr_result
.max
= TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
));
3925 /* If we ended up with a (-INF, +INF) range, set it to
3927 if (vr_result
.min
== TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
))
3928 && vr_result
.max
== TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
)))
3933 /* If the new range is different than the previous value, keep
3935 if (update_value_range (lhs
, &vr_result
))
3936 return SSA_PROP_INTERESTING
;
3938 /* Nothing changed, don't add outgoing edges. */
3939 return SSA_PROP_NOT_INTERESTING
;
3941 /* No match found. Set the LHS to VARYING. */
3943 set_value_range_to_varying (lhs_vr
);
3944 return SSA_PROP_VARYING
;
3947 /* Simplify a division or modulo operator to a right shift or
3948 bitwise and if the first operand is unsigned or is greater
3949 than zero and the second operand is an exact power of two. */
3952 simplify_div_or_mod_using_ranges (tree stmt
, tree rhs
, enum tree_code rhs_code
)
3955 tree op
= TREE_OPERAND (rhs
, 0);
3956 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
3958 if (TYPE_UNSIGNED (TREE_TYPE (op
)))
3960 val
= integer_one_node
;
3964 val
= compare_range_with_value (GT_EXPR
, vr
, integer_zero_node
);
3967 if (val
&& integer_onep (val
))
3970 tree op0
= TREE_OPERAND (rhs
, 0);
3971 tree op1
= TREE_OPERAND (rhs
, 1);
3973 if (rhs_code
== TRUNC_DIV_EXPR
)
3975 t
= build_int_cst (NULL_TREE
, tree_log2 (op1
));
3976 t
= build2 (RSHIFT_EXPR
, TREE_TYPE (op0
), op0
, t
);
3980 t
= build_int_cst (TREE_TYPE (op1
), 1);
3981 t
= int_const_binop (MINUS_EXPR
, op1
, t
, 0);
3982 t
= fold_convert (TREE_TYPE (op0
), t
);
3983 t
= build2 (BIT_AND_EXPR
, TREE_TYPE (op0
), op0
, t
);
3986 TREE_OPERAND (stmt
, 1) = t
;
3991 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
3992 ABS_EXPR. If the operand is <= 0, then simplify the
3993 ABS_EXPR into a NEGATE_EXPR. */
3996 simplify_abs_using_ranges (tree stmt
, tree rhs
)
3999 tree op
= TREE_OPERAND (rhs
, 0);
4000 tree type
= TREE_TYPE (op
);
4001 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
4003 if (TYPE_UNSIGNED (type
))
4005 val
= integer_zero_node
;
4009 val
= compare_range_with_value (LE_EXPR
, vr
, integer_zero_node
);
4012 val
= compare_range_with_value (GE_EXPR
, vr
, integer_zero_node
);
4016 if (integer_zerop (val
))
4017 val
= integer_one_node
;
4018 else if (integer_onep (val
))
4019 val
= integer_zero_node
;
4024 && (integer_onep (val
) || integer_zerop (val
)))
4028 if (integer_onep (val
))
4029 t
= build1 (NEGATE_EXPR
, TREE_TYPE (op
), op
);
4033 TREE_OPERAND (stmt
, 1) = t
;
4039 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
4040 a known value range VR.
4042 If there is one and only one value which will satisfy the
4043 conditional, then return that value. Else return NULL. */
4046 test_for_singularity (enum tree_code cond_code
, tree op0
,
4047 tree op1
, value_range_t
*vr
)
4052 /* Extract minimum/maximum values which satisfy the
4053 the conditional as it was written. */
4054 if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
4056 min
= TYPE_MIN_VALUE (TREE_TYPE (op0
));
4059 if (cond_code
== LT_EXPR
)
4061 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
4062 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (op0
), max
, one
);
4065 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
4067 max
= TYPE_MAX_VALUE (TREE_TYPE (op0
));
4070 if (cond_code
== GT_EXPR
)
4072 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
4073 min
= fold_build2 (PLUS_EXPR
, TREE_TYPE (op0
), min
, one
);
4077 /* Now refine the minimum and maximum values using any
4078 value range information we have for op0. */
4081 if (compare_values (vr
->min
, min
) == -1)
4085 if (compare_values (vr
->max
, max
) == 1)
4090 /* If the new min/max values have converged to a single value,
4091 then there is only one value which can satisfy the condition,
4092 return that value. */
4093 if (operand_equal_p (min
, max
, 0) && is_gimple_min_invariant (min
))
4099 /* Simplify a conditional using a relational operator to an equality
4100 test if the range information indicates only one value can satisfy
4101 the original conditional. */
4104 simplify_cond_using_ranges (tree stmt
)
4106 tree cond
= COND_EXPR_COND (stmt
);
4107 tree op0
= TREE_OPERAND (cond
, 0);
4108 tree op1
= TREE_OPERAND (cond
, 1);
4109 enum tree_code cond_code
= TREE_CODE (cond
);
4111 if (cond_code
!= NE_EXPR
4112 && cond_code
!= EQ_EXPR
4113 && TREE_CODE (op0
) == SSA_NAME
4114 && INTEGRAL_TYPE_P (TREE_TYPE (op0
))
4115 && is_gimple_min_invariant (op1
))
4117 value_range_t
*vr
= get_value_range (op0
);
4119 /* If we have range information for OP0, then we might be
4120 able to simplify this conditional. */
4121 if (vr
->type
== VR_RANGE
)
4123 tree
new = test_for_singularity (cond_code
, op0
, op1
, vr
);
4129 fprintf (dump_file
, "Simplified relational ");
4130 print_generic_expr (dump_file
, cond
, 0);
4131 fprintf (dump_file
, " into ");
4134 COND_EXPR_COND (stmt
)
4135 = build2 (EQ_EXPR
, boolean_type_node
, op0
, new);
4140 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
4141 fprintf (dump_file
, "\n");
4147 /* Try again after inverting the condition. We only deal
4148 with integral types here, so no need to worry about
4149 issues with inverting FP comparisons. */
4150 cond_code
= invert_tree_comparison (cond_code
, false);
4151 new = test_for_singularity (cond_code
, op0
, op1
, vr
);
4157 fprintf (dump_file
, "Simplified relational ");
4158 print_generic_expr (dump_file
, cond
, 0);
4159 fprintf (dump_file
, " into ");
4162 COND_EXPR_COND (stmt
)
4163 = build2 (NE_EXPR
, boolean_type_node
, op0
, new);
4168 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
4169 fprintf (dump_file
, "\n");
4178 /* Simplify STMT using ranges if possible. */
4181 simplify_stmt_using_ranges (tree stmt
)
4183 if (TREE_CODE (stmt
) == MODIFY_EXPR
)
4185 tree rhs
= TREE_OPERAND (stmt
, 1);
4186 enum tree_code rhs_code
= TREE_CODE (rhs
);
4188 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
4189 and BIT_AND_EXPR respectively if the first operand is greater
4190 than zero and the second operand is an exact power of two. */
4191 if ((rhs_code
== TRUNC_DIV_EXPR
|| rhs_code
== TRUNC_MOD_EXPR
)
4192 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0)))
4193 && integer_pow2p (TREE_OPERAND (rhs
, 1)))
4194 simplify_div_or_mod_using_ranges (stmt
, rhs
, rhs_code
);
4196 /* Transform ABS (X) into X or -X as appropriate. */
4197 if (rhs_code
== ABS_EXPR
4198 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == SSA_NAME
4199 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0))))
4200 simplify_abs_using_ranges (stmt
, rhs
);
4202 else if (TREE_CODE (stmt
) == COND_EXPR
4203 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt
)))
4205 simplify_cond_using_ranges (stmt
);
4211 /* Traverse all the blocks folding conditionals with known ranges. */
4217 prop_value_t
*single_val_range
;
4218 bool do_value_subst_p
;
4222 fprintf (dump_file
, "\nValue ranges after VRP:\n\n");
4223 dump_all_value_ranges (dump_file
);
4224 fprintf (dump_file
, "\n");
4227 /* We may have ended with ranges that have exactly one value. Those
4228 values can be substituted as any other copy/const propagated
4229 value using substitute_and_fold. */
4230 single_val_range
= XNEWVEC (prop_value_t
, num_ssa_names
);
4231 memset (single_val_range
, 0, num_ssa_names
* sizeof (*single_val_range
));
4233 do_value_subst_p
= false;
4234 for (i
= 0; i
< num_ssa_names
; i
++)
4236 && vr_value
[i
]->type
== VR_RANGE
4237 && vr_value
[i
]->min
== vr_value
[i
]->max
)
4239 single_val_range
[i
].value
= vr_value
[i
]->min
;
4240 do_value_subst_p
= true;
4243 if (!do_value_subst_p
)
4245 /* We found no single-valued ranges, don't waste time trying to
4246 do single value substitution in substitute_and_fold. */
4247 free (single_val_range
);
4248 single_val_range
= NULL
;
4251 substitute_and_fold (single_val_range
, true);
4253 /* Free allocated memory. */
4254 for (i
= 0; i
< num_ssa_names
; i
++)
4257 BITMAP_FREE (vr_value
[i
]->equiv
);
4261 free (single_val_range
);
4266 /* Main entry point to VRP (Value Range Propagation). This pass is
4267 loosely based on J. R. C. Patterson, ``Accurate Static Branch
4268 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
4269 Programming Language Design and Implementation, pp. 67-78, 1995.
4270 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
4272 This is essentially an SSA-CCP pass modified to deal with ranges
4273 instead of constants.
4275 While propagating ranges, we may find that two or more SSA name
4276 have equivalent, though distinct ranges. For instance,
4279 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
4281 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
4285 In the code above, pointer p_5 has range [q_2, q_2], but from the
4286 code we can also determine that p_5 cannot be NULL and, if q_2 had
4287 a non-varying range, p_5's range should also be compatible with it.
4289 These equivalences are created by two expressions: ASSERT_EXPR and
4290 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
4291 result of another assertion, then we can use the fact that p_5 and
4292 p_4 are equivalent when evaluating p_5's range.
4294 Together with value ranges, we also propagate these equivalences
4295 between names so that we can take advantage of information from
4296 multiple ranges when doing final replacement. Note that this
4297 equivalency relation is transitive but not symmetric.
4299 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
4300 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
4301 in contexts where that assertion does not hold (e.g., in line 6).
4303 TODO, the main difference between this pass and Patterson's is that
4304 we do not propagate edge probabilities. We only compute whether
4305 edges can be taken or not. That is, instead of having a spectrum
4306 of jump probabilities between 0 and 1, we only deal with 0, 1 and
4307 DON'T KNOW. In the future, it may be worthwhile to propagate
4308 probabilities to aid branch prediction. */
4313 insert_range_assertions ();
4315 cfg_loops
= loop_optimizer_init (NULL
);
4317 scev_initialize (cfg_loops
);
4320 ssa_propagate (vrp_visit_stmt
, vrp_visit_phi_node
);
4326 loop_optimizer_finalize (cfg_loops
, NULL
);
4327 current_loops
= NULL
;
4330 remove_range_assertions ();
4336 return flag_tree_vrp
!= 0;
4339 struct tree_opt_pass pass_vrp
=
4342 gate_vrp
, /* gate */
4343 execute_vrp
, /* execute */
4346 0, /* static_pass_number */
4347 TV_TREE_VRP
, /* tv_id */
4348 PROP_ssa
| PROP_alias
, /* properties_required */
4349 0, /* properties_provided */
4350 0, /* properties_destroyed */
4351 0, /* todo_flags_start */
4356 | TODO_update_ssa
, /* todo_flags_finish */