1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005 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
= xmalloc (sizeof (*vr
));
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 /* Remove names from the equivalence set that have ranges
1054 incompatible with VR_P. */
1056 fix_equivalence_set (vr_p
);
1060 /* Extract range information from SSA name VAR and store it in VR. If
1061 VAR has an interesting range, use it. Otherwise, create the
1062 range [VAR, VAR] and return it. This is useful in situations where
1063 we may have conditionals testing values of VARYING names. For
1070 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1074 extract_range_from_ssa_name (value_range_t
*vr
, tree var
)
1076 value_range_t
*var_vr
= get_value_range (var
);
1078 if (var_vr
->type
!= VR_UNDEFINED
&& var_vr
->type
!= VR_VARYING
)
1079 copy_value_range (vr
, var_vr
);
1081 set_value_range (vr
, VR_RANGE
, var
, var
, NULL
);
1083 add_equivalence (vr
->equiv
, var
);
1087 /* Wrapper around int_const_binop. If the operation overflows and we
1088 are not using wrapping arithmetic, then adjust the result to be
1089 -INF or +INF depending on CODE, VAL1 and VAL2. */
1092 vrp_int_const_binop (enum tree_code code
, tree val1
, tree val2
)
1097 return int_const_binop (code
, val1
, val2
, 0);
1099 /* If we are not using wrapping arithmetic, operate symbolically
1100 on -INF and +INF. */
1101 res
= int_const_binop (code
, val1
, val2
, 0);
1103 if (TYPE_UNSIGNED (TREE_TYPE (val1
)))
1105 int checkz
= compare_values (res
, val1
);
1107 /* Ensure that res = val1 + val2 >= val1
1108 or that res = val1 - val2 <= val1. */
1109 if ((code
== PLUS_EXPR
&& !(checkz
== 1 || checkz
== 0))
1110 || (code
== MINUS_EXPR
&& !(checkz
== 0 || checkz
== -1)))
1112 res
= copy_node (res
);
1113 TREE_OVERFLOW (res
) = 1;
1116 /* If the operation overflowed but neither VAL1 nor VAL2 are
1117 overflown, return -INF or +INF depending on the operation
1118 and the combination of signs of the operands. */
1119 else if (TREE_OVERFLOW (res
)
1120 && !TREE_OVERFLOW (val1
)
1121 && !TREE_OVERFLOW (val2
))
1123 int sgn1
= tree_int_cst_sgn (val1
);
1124 int sgn2
= tree_int_cst_sgn (val2
);
1126 /* Notice that we only need to handle the restricted set of
1127 operations handled by extract_range_from_binary_expr.
1128 Among them, only multiplication, addition and subtraction
1129 can yield overflow without overflown operands because we
1130 are working with integral types only... except in the
1131 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1132 for division too. */
1134 /* For multiplication, the sign of the overflow is given
1135 by the comparison of the signs of the operands. */
1136 if ((code
== MULT_EXPR
&& sgn1
== sgn2
)
1137 /* For addition, the operands must be of the same sign
1138 to yield an overflow. Its sign is therefore that
1139 of one of the operands, for example the first. */
1140 || (code
== PLUS_EXPR
&& sgn1
> 0)
1141 /* For subtraction, the operands must be of different
1142 signs to yield an overflow. Its sign is therefore
1143 that of the first operand or the opposite of that
1144 of the second operand. A first operand of 0 counts
1145 as positive here, for the corner case 0 - (-INF),
1146 which overflows, but must yield +INF. */
1147 || (code
== MINUS_EXPR
&& sgn1
>= 0)
1148 /* For division, the only case is -INF / -1 = +INF. */
1149 || code
== TRUNC_DIV_EXPR
1150 || code
== FLOOR_DIV_EXPR
1151 || code
== CEIL_DIV_EXPR
1152 || code
== EXACT_DIV_EXPR
1153 || code
== ROUND_DIV_EXPR
)
1154 return TYPE_MAX_VALUE (TREE_TYPE (res
));
1156 return TYPE_MIN_VALUE (TREE_TYPE (res
));
1163 /* Extract range information from a binary expression EXPR based on
1164 the ranges of each of its operands and the expression code. */
1167 extract_range_from_binary_expr (value_range_t
*vr
, tree expr
)
1169 enum tree_code code
= TREE_CODE (expr
);
1170 tree op0
, op1
, min
, max
;
1172 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1173 value_range_t vr1
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1175 /* Not all binary expressions can be applied to ranges in a
1176 meaningful way. Handle only arithmetic operations. */
1177 if (code
!= PLUS_EXPR
1178 && code
!= MINUS_EXPR
1179 && code
!= MULT_EXPR
1180 && code
!= TRUNC_DIV_EXPR
1181 && code
!= FLOOR_DIV_EXPR
1182 && code
!= CEIL_DIV_EXPR
1183 && code
!= EXACT_DIV_EXPR
1184 && code
!= ROUND_DIV_EXPR
1187 && code
!= BIT_AND_EXPR
1188 && code
!= TRUTH_ANDIF_EXPR
1189 && code
!= TRUTH_ORIF_EXPR
1190 && code
!= TRUTH_AND_EXPR
1191 && code
!= TRUTH_OR_EXPR
1192 && code
!= TRUTH_XOR_EXPR
)
1194 set_value_range_to_varying (vr
);
1198 /* Get value ranges for each operand. For constant operands, create
1199 a new value range with the operand to simplify processing. */
1200 op0
= TREE_OPERAND (expr
, 0);
1201 if (TREE_CODE (op0
) == SSA_NAME
)
1202 vr0
= *(get_value_range (op0
));
1203 else if (is_gimple_min_invariant (op0
))
1204 set_value_range (&vr0
, VR_RANGE
, op0
, op0
, NULL
);
1206 set_value_range_to_varying (&vr0
);
1208 op1
= TREE_OPERAND (expr
, 1);
1209 if (TREE_CODE (op1
) == SSA_NAME
)
1210 vr1
= *(get_value_range (op1
));
1211 else if (is_gimple_min_invariant (op1
))
1212 set_value_range (&vr1
, VR_RANGE
, op1
, op1
, NULL
);
1214 set_value_range_to_varying (&vr1
);
1216 /* If either range is UNDEFINED, so is the result. */
1217 if (vr0
.type
== VR_UNDEFINED
|| vr1
.type
== VR_UNDEFINED
)
1219 set_value_range_to_undefined (vr
);
1223 /* Refuse to operate on VARYING ranges, ranges of different kinds
1224 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1225 because we may be able to derive a useful range even if one of
1226 the operands is VR_VARYING or symbolic range. TODO, we may be
1227 able to derive anti-ranges in some cases. */
1228 if (code
!= BIT_AND_EXPR
1229 && (vr0
.type
== VR_VARYING
1230 || vr1
.type
== VR_VARYING
1231 || vr0
.type
!= vr1
.type
1232 || symbolic_range_p (&vr0
)
1233 || symbolic_range_p (&vr1
)))
1235 set_value_range_to_varying (vr
);
1239 /* Now evaluate the expression to determine the new range. */
1240 if (POINTER_TYPE_P (TREE_TYPE (expr
))
1241 || POINTER_TYPE_P (TREE_TYPE (op0
))
1242 || POINTER_TYPE_P (TREE_TYPE (op1
)))
1244 /* For pointer types, we are really only interested in asserting
1245 whether the expression evaluates to non-NULL. FIXME, we used
1246 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1247 ivopts is generating expressions with pointer multiplication
1249 if (code
== PLUS_EXPR
)
1251 if (range_is_nonnull (&vr0
) || range_is_nonnull (&vr1
))
1252 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1253 else if (range_is_null (&vr0
) && range_is_null (&vr1
))
1254 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1256 set_value_range_to_varying (vr
);
1260 /* Subtracting from a pointer, may yield 0, so just drop the
1261 resulting range to varying. */
1262 set_value_range_to_varying (vr
);
1268 /* For integer ranges, apply the operation to each end of the
1269 range and see what we end up with. */
1270 if (code
== TRUTH_ANDIF_EXPR
1271 || code
== TRUTH_ORIF_EXPR
1272 || code
== TRUTH_AND_EXPR
1273 || code
== TRUTH_OR_EXPR
1274 || code
== TRUTH_XOR_EXPR
)
1276 /* Boolean expressions cannot be folded with int_const_binop. */
1277 min
= fold_binary (code
, TREE_TYPE (expr
), vr0
.min
, vr1
.min
);
1278 max
= fold_binary (code
, TREE_TYPE (expr
), vr0
.max
, vr1
.max
);
1280 else if (code
== PLUS_EXPR
1282 || code
== MAX_EXPR
)
1284 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1285 VR_VARYING. It would take more effort to compute a precise
1286 range for such a case. For example, if we have op0 == 1 and
1287 op1 == -1 with their ranges both being ~[0,0], we would have
1288 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1289 Note that we are guaranteed to have vr0.type == vr1.type at
1291 if (code
== PLUS_EXPR
&& vr0
.type
== VR_ANTI_RANGE
)
1293 set_value_range_to_varying (vr
);
1297 /* For operations that make the resulting range directly
1298 proportional to the original ranges, apply the operation to
1299 the same end of each range. */
1300 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1301 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.max
);
1303 else if (code
== MULT_EXPR
1304 || code
== TRUNC_DIV_EXPR
1305 || code
== FLOOR_DIV_EXPR
1306 || code
== CEIL_DIV_EXPR
1307 || code
== EXACT_DIV_EXPR
1308 || code
== ROUND_DIV_EXPR
)
1313 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1314 drop to VR_VARYING. It would take more effort to compute a
1315 precise range for such a case. For example, if we have
1316 op0 == 65536 and op1 == 65536 with their ranges both being
1317 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1318 we cannot claim that the product is in ~[0,0]. Note that we
1319 are guaranteed to have vr0.type == vr1.type at this
1321 if (code
== MULT_EXPR
1322 && vr0
.type
== VR_ANTI_RANGE
1323 && (flag_wrapv
|| TYPE_UNSIGNED (TREE_TYPE (op0
))))
1325 set_value_range_to_varying (vr
);
1329 /* Multiplications and divisions are a bit tricky to handle,
1330 depending on the mix of signs we have in the two ranges, we
1331 need to operate on different values to get the minimum and
1332 maximum values for the new range. One approach is to figure
1333 out all the variations of range combinations and do the
1336 However, this involves several calls to compare_values and it
1337 is pretty convoluted. It's simpler to do the 4 operations
1338 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1339 MAX1) and then figure the smallest and largest values to form
1342 /* Divisions by zero result in a VARYING value. */
1343 if (code
!= MULT_EXPR
1344 && (vr0
.type
== VR_ANTI_RANGE
|| range_includes_zero_p (&vr1
)))
1346 set_value_range_to_varying (vr
);
1350 /* Compute the 4 cross operations. */
1351 val
[0] = vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1353 val
[1] = (vr1
.max
!= vr1
.min
)
1354 ? vrp_int_const_binop (code
, vr0
.min
, vr1
.max
)
1357 val
[2] = (vr0
.max
!= vr0
.min
)
1358 ? vrp_int_const_binop (code
, vr0
.max
, vr1
.min
)
1361 val
[3] = (vr0
.min
!= vr0
.max
&& vr1
.min
!= vr1
.max
)
1362 ? vrp_int_const_binop (code
, vr0
.max
, vr1
.max
)
1365 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1369 for (i
= 1; i
< 4; i
++)
1371 if (TREE_OVERFLOW (min
) || TREE_OVERFLOW (max
))
1376 if (TREE_OVERFLOW (val
[i
]))
1378 /* If we found an overflowed value, set MIN and MAX
1379 to it so that we set the resulting range to
1385 if (compare_values (val
[i
], min
) == -1)
1388 if (compare_values (val
[i
], max
) == 1)
1393 else if (code
== MINUS_EXPR
)
1395 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1396 VR_VARYING. It would take more effort to compute a precise
1397 range for such a case. For example, if we have op0 == 1 and
1398 op1 == 1 with their ranges both being ~[0,0], we would have
1399 op0 - op1 == 0, so we cannot claim that the difference is in
1400 ~[0,0]. Note that we are guaranteed to have
1401 vr0.type == vr1.type at this point. */
1402 if (vr0
.type
== VR_ANTI_RANGE
)
1404 set_value_range_to_varying (vr
);
1408 /* For MINUS_EXPR, apply the operation to the opposite ends of
1410 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.max
);
1411 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.min
);
1413 else if (code
== BIT_AND_EXPR
)
1415 if (vr0
.type
== VR_RANGE
1416 && vr0
.min
== vr0
.max
1417 && tree_expr_nonnegative_p (vr0
.max
)
1418 && TREE_CODE (vr0
.max
) == INTEGER_CST
)
1420 min
= fold_convert (TREE_TYPE (expr
), integer_zero_node
);
1423 else if (vr1
.type
== VR_RANGE
1424 && vr1
.min
== vr1
.max
1425 && tree_expr_nonnegative_p (vr1
.max
)
1426 && TREE_CODE (vr1
.max
) == INTEGER_CST
)
1428 vr0
.type
= VR_RANGE
;
1429 min
= fold_convert (TREE_TYPE (expr
), integer_zero_node
);
1434 set_value_range_to_varying (vr
);
1441 /* If either MIN or MAX overflowed, then set the resulting range to
1443 if (TREE_OVERFLOW (min
) || TREE_OVERFLOW (max
))
1445 set_value_range_to_varying (vr
);
1449 cmp
= compare_values (min
, max
);
1450 if (cmp
== -2 || cmp
== 1)
1452 /* If the new range has its limits swapped around (MIN > MAX),
1453 then the operation caused one of them to wrap around, mark
1454 the new range VARYING. */
1455 set_value_range_to_varying (vr
);
1458 set_value_range (vr
, vr0
.type
, min
, max
, NULL
);
1462 /* Extract range information from a unary expression EXPR based on
1463 the range of its operand and the expression code. */
1466 extract_range_from_unary_expr (value_range_t
*vr
, tree expr
)
1468 enum tree_code code
= TREE_CODE (expr
);
1471 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1473 /* Refuse to operate on certain unary expressions for which we
1474 cannot easily determine a resulting range. */
1475 if (code
== FIX_TRUNC_EXPR
1476 || code
== FIX_CEIL_EXPR
1477 || code
== FIX_FLOOR_EXPR
1478 || code
== FIX_ROUND_EXPR
1479 || code
== FLOAT_EXPR
1480 || code
== BIT_NOT_EXPR
1481 || code
== NON_LVALUE_EXPR
1482 || code
== CONJ_EXPR
)
1484 set_value_range_to_varying (vr
);
1488 /* Get value ranges for the operand. For constant operands, create
1489 a new value range with the operand to simplify processing. */
1490 op0
= TREE_OPERAND (expr
, 0);
1491 if (TREE_CODE (op0
) == SSA_NAME
)
1492 vr0
= *(get_value_range (op0
));
1493 else if (is_gimple_min_invariant (op0
))
1494 set_value_range (&vr0
, VR_RANGE
, op0
, op0
, NULL
);
1496 set_value_range_to_varying (&vr0
);
1498 /* If VR0 is UNDEFINED, so is the result. */
1499 if (vr0
.type
== VR_UNDEFINED
)
1501 set_value_range_to_undefined (vr
);
1505 /* Refuse to operate on varying and symbolic ranges. Also, if the
1506 operand is neither a pointer nor an integral type, set the
1507 resulting range to VARYING. TODO, in some cases we may be able
1508 to derive anti-ranges (like nonzero values). */
1509 if (vr0
.type
== VR_VARYING
1510 || (!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
1511 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
1512 || symbolic_range_p (&vr0
))
1514 set_value_range_to_varying (vr
);
1518 /* If the expression involves pointers, we are only interested in
1519 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1520 if (POINTER_TYPE_P (TREE_TYPE (expr
)) || POINTER_TYPE_P (TREE_TYPE (op0
)))
1522 if (range_is_nonnull (&vr0
) || tree_expr_nonzero_p (expr
))
1523 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1524 else if (range_is_null (&vr0
))
1525 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1527 set_value_range_to_varying (vr
);
1532 /* Handle unary expressions on integer ranges. */
1533 if (code
== NOP_EXPR
|| code
== CONVERT_EXPR
)
1535 tree inner_type
= TREE_TYPE (op0
);
1536 tree outer_type
= TREE_TYPE (expr
);
1538 /* If VR0 represents a simple range, then try to convert
1539 the min and max values for the range to the same type
1540 as OUTER_TYPE. If the results compare equal to VR0's
1541 min and max values and the new min is still less than
1542 or equal to the new max, then we can safely use the newly
1543 computed range for EXPR. This allows us to compute
1544 accurate ranges through many casts. */
1545 if (vr0
.type
== VR_RANGE
)
1547 tree new_min
, new_max
;
1549 /* Convert VR0's min/max to OUTER_TYPE. */
1550 new_min
= fold_convert (outer_type
, vr0
.min
);
1551 new_max
= fold_convert (outer_type
, vr0
.max
);
1553 /* Verify the new min/max values are gimple values and
1554 that they compare equal to VR0's min/max values. */
1555 if (is_gimple_val (new_min
)
1556 && is_gimple_val (new_max
)
1557 && tree_int_cst_equal (new_min
, vr0
.min
)
1558 && tree_int_cst_equal (new_max
, vr0
.max
)
1559 && compare_values (new_min
, new_max
) <= 0
1560 && compare_values (new_min
, new_max
) >= -1)
1562 set_value_range (vr
, VR_RANGE
, new_min
, new_max
, vr
->equiv
);
1567 /* When converting types of different sizes, set the result to
1568 VARYING. Things like sign extensions and precision loss may
1569 change the range. For instance, if x_3 is of type 'long long
1570 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1571 is impossible to know at compile time whether y_5 will be
1573 if (TYPE_SIZE (inner_type
) != TYPE_SIZE (outer_type
)
1574 || TYPE_PRECISION (inner_type
) != TYPE_PRECISION (outer_type
))
1576 set_value_range_to_varying (vr
);
1581 /* Apply the operation to each end of the range and see what we end
1583 if (code
== NEGATE_EXPR
1584 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
1586 /* NEGATE_EXPR flips the range around. */
1587 min
= (vr0
.max
== TYPE_MAX_VALUE (TREE_TYPE (expr
)) && !flag_wrapv
)
1588 ? TYPE_MIN_VALUE (TREE_TYPE (expr
))
1589 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1591 max
= (vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
)) && !flag_wrapv
)
1592 ? TYPE_MAX_VALUE (TREE_TYPE (expr
))
1593 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1595 else if (code
== ABS_EXPR
1596 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
1598 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1601 && ((vr0
.type
== VR_RANGE
1602 && vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
)))
1603 || (vr0
.type
== VR_ANTI_RANGE
1604 && vr0
.min
!= TYPE_MIN_VALUE (TREE_TYPE (expr
))
1605 && !range_includes_zero_p (&vr0
))))
1607 set_value_range_to_varying (vr
);
1611 /* ABS_EXPR may flip the range around, if the original range
1612 included negative values. */
1613 min
= (vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
)))
1614 ? TYPE_MAX_VALUE (TREE_TYPE (expr
))
1615 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1617 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1619 cmp
= compare_values (min
, max
);
1621 /* If a VR_ANTI_RANGEs contains zero, then we have
1622 ~[-INF, min(MIN, MAX)]. */
1623 if (vr0
.type
== VR_ANTI_RANGE
)
1625 if (range_includes_zero_p (&vr0
))
1627 tree type_min_value
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
1629 /* Take the lower of the two values. */
1633 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1634 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1635 flag_wrapv is set and the original anti-range doesn't include
1636 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1637 min
= (flag_wrapv
&& vr0
.min
!= type_min_value
1638 ? int_const_binop (PLUS_EXPR
,
1640 integer_one_node
, 0)
1645 /* All else has failed, so create the range [0, INF], even for
1646 flag_wrapv since TYPE_MIN_VALUE is in the original
1648 vr0
.type
= VR_RANGE
;
1649 min
= build_int_cst (TREE_TYPE (expr
), 0);
1650 max
= TYPE_MAX_VALUE (TREE_TYPE (expr
));
1654 /* If the range contains zero then we know that the minimum value in the
1655 range will be zero. */
1656 else if (range_includes_zero_p (&vr0
))
1660 min
= build_int_cst (TREE_TYPE (expr
), 0);
1664 /* If the range was reversed, swap MIN and MAX. */
1675 /* Otherwise, operate on each end of the range. */
1676 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1677 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1680 cmp
= compare_values (min
, max
);
1681 if (cmp
== -2 || cmp
== 1)
1683 /* If the new range has its limits swapped around (MIN > MAX),
1684 then the operation caused one of them to wrap around, mark
1685 the new range VARYING. */
1686 set_value_range_to_varying (vr
);
1689 set_value_range (vr
, vr0
.type
, min
, max
, NULL
);
1693 /* Extract range information from a comparison expression EXPR based
1694 on the range of its operand and the expression code. */
1697 extract_range_from_comparison (value_range_t
*vr
, tree expr
)
1699 tree val
= vrp_evaluate_conditional (expr
, false);
1702 /* Since this expression was found on the RHS of an assignment,
1703 its type may be different from _Bool. Convert VAL to EXPR's
1705 val
= fold_convert (TREE_TYPE (expr
), val
);
1706 set_value_range (vr
, VR_RANGE
, val
, val
, vr
->equiv
);
1709 set_value_range_to_varying (vr
);
1713 /* Try to compute a useful range out of expression EXPR and store it
1717 extract_range_from_expr (value_range_t
*vr
, tree expr
)
1719 enum tree_code code
= TREE_CODE (expr
);
1721 if (code
== ASSERT_EXPR
)
1722 extract_range_from_assert (vr
, expr
);
1723 else if (code
== SSA_NAME
)
1724 extract_range_from_ssa_name (vr
, expr
);
1725 else if (TREE_CODE_CLASS (code
) == tcc_binary
1726 || code
== TRUTH_ANDIF_EXPR
1727 || code
== TRUTH_ORIF_EXPR
1728 || code
== TRUTH_AND_EXPR
1729 || code
== TRUTH_OR_EXPR
1730 || code
== TRUTH_XOR_EXPR
)
1731 extract_range_from_binary_expr (vr
, expr
);
1732 else if (TREE_CODE_CLASS (code
) == tcc_unary
)
1733 extract_range_from_unary_expr (vr
, expr
);
1734 else if (TREE_CODE_CLASS (code
) == tcc_comparison
)
1735 extract_range_from_comparison (vr
, expr
);
1736 else if (is_gimple_min_invariant (expr
))
1737 set_value_range (vr
, VR_RANGE
, expr
, expr
, NULL
);
1738 else if (vrp_expr_computes_nonzero (expr
))
1739 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1741 set_value_range_to_varying (vr
);
1744 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1745 would be profitable to adjust VR using scalar evolution information
1746 for VAR. If so, update VR with the new limits. */
1749 adjust_range_with_scev (value_range_t
*vr
, struct loop
*loop
, tree stmt
,
1752 tree init
, step
, chrec
;
1753 bool init_is_max
, unknown_max
;
1755 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1756 better opportunities than a regular range, but I'm not sure. */
1757 if (vr
->type
== VR_ANTI_RANGE
)
1760 chrec
= instantiate_parameters (loop
, analyze_scalar_evolution (loop
, var
));
1761 if (TREE_CODE (chrec
) != POLYNOMIAL_CHREC
)
1764 init
= initial_condition_in_loop_num (chrec
, loop
->num
);
1765 step
= evolution_part_in_loop_num (chrec
, loop
->num
);
1767 /* If STEP is symbolic, we can't know whether INIT will be the
1768 minimum or maximum value in the range. */
1769 if (step
== NULL_TREE
1770 || !is_gimple_min_invariant (step
))
1773 /* Do not adjust ranges when chrec may wrap. */
1774 if (scev_probably_wraps_p (chrec_type (chrec
), init
, step
, stmt
,
1775 cfg_loops
->parray
[CHREC_VARIABLE (chrec
)],
1776 &init_is_max
, &unknown_max
)
1780 if (!POINTER_TYPE_P (TREE_TYPE (init
))
1781 && (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
))
1783 /* For VARYING or UNDEFINED ranges, just about anything we get
1784 from scalar evolutions should be better. */
1786 set_value_range (vr
, VR_RANGE
, TYPE_MIN_VALUE (TREE_TYPE (init
)),
1789 set_value_range (vr
, VR_RANGE
, init
, TYPE_MAX_VALUE (TREE_TYPE (init
)),
1792 else if (vr
->type
== VR_RANGE
)
1799 /* INIT is the maximum value. If INIT is lower than VR->MAX
1800 but no smaller than VR->MIN, set VR->MAX to INIT. */
1801 if (compare_values (init
, max
) == -1)
1805 /* If we just created an invalid range with the minimum
1806 greater than the maximum, take the minimum all the
1808 if (compare_values (min
, max
) == 1)
1809 min
= TYPE_MIN_VALUE (TREE_TYPE (min
));
1814 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
1815 if (compare_values (init
, min
) == 1)
1819 /* If we just created an invalid range with the minimum
1820 greater than the maximum, take the maximum all the
1822 if (compare_values (min
, max
) == 1)
1823 max
= TYPE_MAX_VALUE (TREE_TYPE (max
));
1827 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
1832 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
1834 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
1835 all the values in the ranges.
1837 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
1839 - Return NULL_TREE if it is not always possible to determine the
1840 value of the comparison. */
1844 compare_ranges (enum tree_code comp
, value_range_t
*vr0
, value_range_t
*vr1
)
1846 /* VARYING or UNDEFINED ranges cannot be compared. */
1847 if (vr0
->type
== VR_VARYING
1848 || vr0
->type
== VR_UNDEFINED
1849 || vr1
->type
== VR_VARYING
1850 || vr1
->type
== VR_UNDEFINED
)
1853 /* Anti-ranges need to be handled separately. */
1854 if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
1856 /* If both are anti-ranges, then we cannot compute any
1858 if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
1861 /* These comparisons are never statically computable. */
1868 /* Equality can be computed only between a range and an
1869 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
1870 if (vr0
->type
== VR_RANGE
)
1872 /* To simplify processing, make VR0 the anti-range. */
1873 value_range_t
*tmp
= vr0
;
1878 gcc_assert (comp
== NE_EXPR
|| comp
== EQ_EXPR
);
1880 if (compare_values (vr0
->min
, vr1
->min
) == 0
1881 && compare_values (vr0
->max
, vr1
->max
) == 0)
1882 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
1887 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
1888 operands around and change the comparison code. */
1889 if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
1892 comp
= (comp
== GT_EXPR
) ? LT_EXPR
: LE_EXPR
;
1898 if (comp
== EQ_EXPR
)
1900 /* Equality may only be computed if both ranges represent
1901 exactly one value. */
1902 if (compare_values (vr0
->min
, vr0
->max
) == 0
1903 && compare_values (vr1
->min
, vr1
->max
) == 0)
1905 int cmp_min
= compare_values (vr0
->min
, vr1
->min
);
1906 int cmp_max
= compare_values (vr0
->max
, vr1
->max
);
1907 if (cmp_min
== 0 && cmp_max
== 0)
1908 return boolean_true_node
;
1909 else if (cmp_min
!= -2 && cmp_max
!= -2)
1910 return boolean_false_node
;
1912 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
1913 else if (compare_values (vr0
->min
, vr1
->max
) == 1
1914 || compare_values (vr1
->min
, vr0
->max
) == 1)
1915 return boolean_false_node
;
1919 else if (comp
== NE_EXPR
)
1923 /* If VR0 is completely to the left or completely to the right
1924 of VR1, they are always different. Notice that we need to
1925 make sure that both comparisons yield similar results to
1926 avoid comparing values that cannot be compared at
1928 cmp1
= compare_values (vr0
->max
, vr1
->min
);
1929 cmp2
= compare_values (vr0
->min
, vr1
->max
);
1930 if ((cmp1
== -1 && cmp2
== -1) || (cmp1
== 1 && cmp2
== 1))
1931 return boolean_true_node
;
1933 /* If VR0 and VR1 represent a single value and are identical,
1935 else if (compare_values (vr0
->min
, vr0
->max
) == 0
1936 && compare_values (vr1
->min
, vr1
->max
) == 0
1937 && compare_values (vr0
->min
, vr1
->min
) == 0
1938 && compare_values (vr0
->max
, vr1
->max
) == 0)
1939 return boolean_false_node
;
1941 /* Otherwise, they may or may not be different. */
1945 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
1949 /* If VR0 is to the left of VR1, return true. */
1950 tst
= compare_values (vr0
->max
, vr1
->min
);
1951 if ((comp
== LT_EXPR
&& tst
== -1)
1952 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
1953 return boolean_true_node
;
1955 /* If VR0 is to the right of VR1, return false. */
1956 tst
= compare_values (vr0
->min
, vr1
->max
);
1957 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
1958 || (comp
== LE_EXPR
&& tst
== 1))
1959 return boolean_false_node
;
1961 /* Otherwise, we don't know. */
1969 /* Given a value range VR, a value VAL and a comparison code COMP, return
1970 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
1971 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
1972 always returns false. Return NULL_TREE if it is not always
1973 possible to determine the value of the comparison. */
1976 compare_range_with_value (enum tree_code comp
, value_range_t
*vr
, tree val
)
1978 if (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
)
1981 /* Anti-ranges need to be handled separately. */
1982 if (vr
->type
== VR_ANTI_RANGE
)
1984 /* For anti-ranges, the only predicates that we can compute at
1985 compile time are equality and inequality. */
1992 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
1993 if (value_inside_range (val
, vr
) == 1)
1994 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
1999 if (comp
== EQ_EXPR
)
2001 /* EQ_EXPR may only be computed if VR represents exactly
2003 if (compare_values (vr
->min
, vr
->max
) == 0)
2005 int cmp
= compare_values (vr
->min
, val
);
2007 return boolean_true_node
;
2008 else if (cmp
== -1 || cmp
== 1 || cmp
== 2)
2009 return boolean_false_node
;
2011 else if (compare_values (val
, vr
->min
) == -1
2012 || compare_values (vr
->max
, val
) == -1)
2013 return boolean_false_node
;
2017 else if (comp
== NE_EXPR
)
2019 /* If VAL is not inside VR, then they are always different. */
2020 if (compare_values (vr
->max
, val
) == -1
2021 || compare_values (vr
->min
, val
) == 1)
2022 return boolean_true_node
;
2024 /* If VR represents exactly one value equal to VAL, then return
2026 if (compare_values (vr
->min
, vr
->max
) == 0
2027 && compare_values (vr
->min
, val
) == 0)
2028 return boolean_false_node
;
2030 /* Otherwise, they may or may not be different. */
2033 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
2037 /* If VR is to the left of VAL, return true. */
2038 tst
= compare_values (vr
->max
, val
);
2039 if ((comp
== LT_EXPR
&& tst
== -1)
2040 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
2041 return boolean_true_node
;
2043 /* If VR is to the right of VAL, return false. */
2044 tst
= compare_values (vr
->min
, val
);
2045 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
2046 || (comp
== LE_EXPR
&& tst
== 1))
2047 return boolean_false_node
;
2049 /* Otherwise, we don't know. */
2052 else if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
2056 /* If VR is to the right of VAL, return true. */
2057 tst
= compare_values (vr
->min
, val
);
2058 if ((comp
== GT_EXPR
&& tst
== 1)
2059 || (comp
== GE_EXPR
&& (tst
== 0 || tst
== 1)))
2060 return boolean_true_node
;
2062 /* If VR is to the left of VAL, return false. */
2063 tst
= compare_values (vr
->max
, val
);
2064 if ((comp
== GT_EXPR
&& (tst
== -1 || tst
== 0))
2065 || (comp
== GE_EXPR
&& tst
== -1))
2066 return boolean_false_node
;
2068 /* Otherwise, we don't know. */
2076 /* Debugging dumps. */
2078 void dump_value_range (FILE *, value_range_t
*);
2079 void debug_value_range (value_range_t
*);
2080 void dump_all_value_ranges (FILE *);
2081 void debug_all_value_ranges (void);
2082 void dump_vr_equiv (FILE *, bitmap
);
2083 void debug_vr_equiv (bitmap
);
2086 /* Dump value range VR to FILE. */
2089 dump_value_range (FILE *file
, value_range_t
*vr
)
2092 fprintf (file
, "[]");
2093 else if (vr
->type
== VR_UNDEFINED
)
2094 fprintf (file
, "UNDEFINED");
2095 else if (vr
->type
== VR_RANGE
|| vr
->type
== VR_ANTI_RANGE
)
2097 tree type
= TREE_TYPE (vr
->min
);
2099 fprintf (file
, "%s[", (vr
->type
== VR_ANTI_RANGE
) ? "~" : "");
2101 if (INTEGRAL_TYPE_P (type
)
2102 && !TYPE_UNSIGNED (type
)
2103 && vr
->min
== TYPE_MIN_VALUE (type
))
2104 fprintf (file
, "-INF");
2106 print_generic_expr (file
, vr
->min
, 0);
2108 fprintf (file
, ", ");
2110 if (INTEGRAL_TYPE_P (type
)
2111 && vr
->max
== TYPE_MAX_VALUE (type
))
2112 fprintf (file
, "+INF");
2114 print_generic_expr (file
, vr
->max
, 0);
2116 fprintf (file
, "]");
2123 fprintf (file
, " EQUIVALENCES: { ");
2125 EXECUTE_IF_SET_IN_BITMAP (vr
->equiv
, 0, i
, bi
)
2127 print_generic_expr (file
, ssa_name (i
), 0);
2128 fprintf (file
, " ");
2132 fprintf (file
, "} (%u elements)", c
);
2135 else if (vr
->type
== VR_VARYING
)
2136 fprintf (file
, "VARYING");
2138 fprintf (file
, "INVALID RANGE");
2142 /* Dump value range VR to stderr. */
2145 debug_value_range (value_range_t
*vr
)
2147 dump_value_range (stderr
, vr
);
2151 /* Dump value ranges of all SSA_NAMEs to FILE. */
2154 dump_all_value_ranges (FILE *file
)
2158 for (i
= 0; i
< num_ssa_names
; i
++)
2162 print_generic_expr (file
, ssa_name (i
), 0);
2163 fprintf (file
, ": ");
2164 dump_value_range (file
, vr_value
[i
]);
2165 fprintf (file
, "\n");
2169 fprintf (file
, "\n");
2173 /* Dump all value ranges to stderr. */
2176 debug_all_value_ranges (void)
2178 dump_all_value_ranges (stderr
);
2182 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
2183 create a new SSA name N and return the assertion assignment
2184 'V = ASSERT_EXPR <V, V OP W>'. */
2187 build_assert_expr_for (tree cond
, tree v
)
2191 gcc_assert (TREE_CODE (v
) == SSA_NAME
);
2192 n
= duplicate_ssa_name (v
, NULL_TREE
);
2194 if (COMPARISON_CLASS_P (cond
))
2196 tree a
= build2 (ASSERT_EXPR
, TREE_TYPE (v
), v
, cond
);
2197 assertion
= build2 (MODIFY_EXPR
, TREE_TYPE (v
), n
, a
);
2199 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
)
2201 /* Given !V, build the assignment N = false. */
2202 tree op0
= TREE_OPERAND (cond
, 0);
2203 gcc_assert (op0
== v
);
2204 assertion
= build2 (MODIFY_EXPR
, TREE_TYPE (v
), n
, boolean_false_node
);
2206 else if (TREE_CODE (cond
) == SSA_NAME
)
2208 /* Given V, build the assignment N = true. */
2209 gcc_assert (v
== cond
);
2210 assertion
= build2 (MODIFY_EXPR
, TREE_TYPE (v
), n
, boolean_true_node
);
2215 SSA_NAME_DEF_STMT (n
) = assertion
;
2217 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
2218 operand of the ASSERT_EXPR. Register the new name and the old one
2219 in the replacement table so that we can fix the SSA web after
2220 adding all the ASSERT_EXPRs. */
2221 register_new_name_mapping (n
, v
);
2227 /* Return false if EXPR is a predicate expression involving floating
2231 fp_predicate (tree expr
)
2233 return (COMPARISON_CLASS_P (expr
)
2234 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr
, 0))));
2238 /* If the range of values taken by OP can be inferred after STMT executes,
2239 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2240 describes the inferred range. Return true if a range could be
2244 infer_value_range (tree stmt
, tree op
, enum tree_code
*comp_code_p
, tree
*val_p
)
2247 *comp_code_p
= ERROR_MARK
;
2249 /* Do not attempt to infer anything in names that flow through
2251 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op
))
2254 /* Similarly, don't infer anything from statements that may throw
2256 if (tree_could_throw_p (stmt
))
2259 /* If STMT is the last statement of a basic block with no
2260 successors, there is no point inferring anything about any of its
2261 operands. We would not be able to find a proper insertion point
2262 for the assertion, anyway. */
2263 if (stmt_ends_bb_p (stmt
) && EDGE_COUNT (bb_for_stmt (stmt
)->succs
) == 0)
2266 if (POINTER_TYPE_P (TREE_TYPE (op
)))
2269 unsigned num_uses
, num_derefs
;
2271 count_uses_and_derefs (op
, stmt
, &num_uses
, &num_derefs
, &is_store
);
2272 if (num_derefs
> 0 && flag_delete_null_pointer_checks
)
2274 /* We can only assume that a pointer dereference will yield
2275 non-NULL if -fdelete-null-pointer-checks is enabled. */
2276 *val_p
= build_int_cst (TREE_TYPE (op
), 0);
2277 *comp_code_p
= NE_EXPR
;
2286 void dump_asserts_for (FILE *, tree
);
2287 void debug_asserts_for (tree
);
2288 void dump_all_asserts (FILE *);
2289 void debug_all_asserts (void);
2291 /* Dump all the registered assertions for NAME to FILE. */
2294 dump_asserts_for (FILE *file
, tree name
)
2298 fprintf (file
, "Assertions to be inserted for ");
2299 print_generic_expr (file
, name
, 0);
2300 fprintf (file
, "\n");
2302 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
2305 fprintf (file
, "\t");
2306 print_generic_expr (file
, bsi_stmt (loc
->si
), 0);
2307 fprintf (file
, "\n\tBB #%d", loc
->bb
->index
);
2310 fprintf (file
, "\n\tEDGE %d->%d", loc
->e
->src
->index
,
2311 loc
->e
->dest
->index
);
2312 dump_edge_info (file
, loc
->e
, 0);
2314 fprintf (file
, "\n\tPREDICATE: ");
2315 print_generic_expr (file
, name
, 0);
2316 fprintf (file
, " %s ", tree_code_name
[(int)loc
->comp_code
]);
2317 print_generic_expr (file
, loc
->val
, 0);
2318 fprintf (file
, "\n\n");
2322 fprintf (file
, "\n");
2326 /* Dump all the registered assertions for NAME to stderr. */
2329 debug_asserts_for (tree name
)
2331 dump_asserts_for (stderr
, name
);
2335 /* Dump all the registered assertions for all the names to FILE. */
2338 dump_all_asserts (FILE *file
)
2343 fprintf (file
, "\nASSERT_EXPRs to be inserted\n\n");
2344 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
2345 dump_asserts_for (file
, ssa_name (i
));
2346 fprintf (file
, "\n");
2350 /* Dump all the registered assertions for all the names to stderr. */
2353 debug_all_asserts (void)
2355 dump_all_asserts (stderr
);
2359 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2360 'NAME COMP_CODE VAL' at a location that dominates block BB or
2361 E->DEST, then register this location as a possible insertion point
2362 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2364 BB, E and SI provide the exact insertion point for the new
2365 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2366 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2367 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2368 must not be NULL. */
2371 register_new_assert_for (tree name
,
2372 enum tree_code comp_code
,
2376 block_stmt_iterator si
)
2378 assert_locus_t n
, loc
, last_loc
;
2380 basic_block dest_bb
;
2382 #if defined ENABLE_CHECKING
2383 gcc_assert (bb
== NULL
|| e
== NULL
);
2386 gcc_assert (TREE_CODE (bsi_stmt (si
)) != COND_EXPR
2387 && TREE_CODE (bsi_stmt (si
)) != SWITCH_EXPR
);
2390 /* The new assertion A will be inserted at BB or E. We need to
2391 determine if the new location is dominated by a previously
2392 registered location for A. If we are doing an edge insertion,
2393 assume that A will be inserted at E->DEST. Note that this is not
2396 If E is a critical edge, it will be split. But even if E is
2397 split, the new block will dominate the same set of blocks that
2400 The reverse, however, is not true, blocks dominated by E->DEST
2401 will not be dominated by the new block created to split E. So,
2402 if the insertion location is on a critical edge, we will not use
2403 the new location to move another assertion previously registered
2404 at a block dominated by E->DEST. */
2405 dest_bb
= (bb
) ? bb
: e
->dest
;
2407 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2408 VAL at a block dominating DEST_BB, then we don't need to insert a new
2409 one. Similarly, if the same assertion already exists at a block
2410 dominated by DEST_BB and the new location is not on a critical
2411 edge, then update the existing location for the assertion (i.e.,
2412 move the assertion up in the dominance tree).
2414 Note, this is implemented as a simple linked list because there
2415 should not be more than a handful of assertions registered per
2416 name. If this becomes a performance problem, a table hashed by
2417 COMP_CODE and VAL could be implemented. */
2418 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
2423 if (loc
->comp_code
== comp_code
2425 || operand_equal_p (loc
->val
, val
, 0)))
2427 /* If the assertion NAME COMP_CODE VAL has already been
2428 registered at a basic block that dominates DEST_BB, then
2429 we don't need to insert the same assertion again. Note
2430 that we don't check strict dominance here to avoid
2431 replicating the same assertion inside the same basic
2432 block more than once (e.g., when a pointer is
2433 dereferenced several times inside a block).
2435 An exception to this rule are edge insertions. If the
2436 new assertion is to be inserted on edge E, then it will
2437 dominate all the other insertions that we may want to
2438 insert in DEST_BB. So, if we are doing an edge
2439 insertion, don't do this dominance check. */
2441 && dominated_by_p (CDI_DOMINATORS
, dest_bb
, loc
->bb
))
2444 /* Otherwise, if E is not a critical edge and DEST_BB
2445 dominates the existing location for the assertion, move
2446 the assertion up in the dominance tree by updating its
2447 location information. */
2448 if ((e
== NULL
|| !EDGE_CRITICAL_P (e
))
2449 && dominated_by_p (CDI_DOMINATORS
, loc
->bb
, dest_bb
))
2458 /* Update the last node of the list and move to the next one. */
2463 /* If we didn't find an assertion already registered for
2464 NAME COMP_CODE VAL, add a new one at the end of the list of
2465 assertions associated with NAME. */
2466 n
= xmalloc (sizeof (*n
));
2470 n
->comp_code
= comp_code
;
2477 asserts_for
[SSA_NAME_VERSION (name
)] = n
;
2479 bitmap_set_bit (need_assert_for
, SSA_NAME_VERSION (name
));
2483 /* Try to register an edge assertion for SSA name NAME on edge E for
2484 the conditional jump pointed to by SI. Return true if an assertion
2485 for NAME could be registered. */
2488 register_edge_assert_for (tree name
, edge e
, block_stmt_iterator si
)
2491 enum tree_code comp_code
;
2493 stmt
= bsi_stmt (si
);
2495 /* Do not attempt to infer anything in names that flow through
2497 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name
))
2500 /* If NAME was not found in the sub-graph reachable from E, then
2501 there's nothing to do. */
2502 if (!TEST_BIT (found_in_subgraph
, SSA_NAME_VERSION (name
)))
2505 /* We found a use of NAME in the sub-graph rooted at E->DEST.
2506 Register an assertion for NAME according to the value that NAME
2508 if (TREE_CODE (stmt
) == COND_EXPR
)
2510 /* If BB ends in a COND_EXPR then NAME then we should insert
2511 the original predicate on EDGE_TRUE_VALUE and the
2512 opposite predicate on EDGE_FALSE_VALUE. */
2513 tree cond
= COND_EXPR_COND (stmt
);
2514 bool is_else_edge
= (e
->flags
& EDGE_FALSE_VALUE
) != 0;
2516 /* Predicates may be a single SSA name or NAME OP VAL. */
2519 /* If the predicate is a name, it must be NAME, in which
2520 case we create the predicate NAME == true or
2521 NAME == false accordingly. */
2522 comp_code
= EQ_EXPR
;
2523 val
= (is_else_edge
) ? boolean_false_node
: boolean_true_node
;
2527 /* Otherwise, we have a comparison of the form NAME COMP VAL
2528 or VAL COMP NAME. */
2529 if (name
== TREE_OPERAND (cond
, 1))
2531 /* If the predicate is of the form VAL COMP NAME, flip
2532 COMP around because we need to register NAME as the
2533 first operand in the predicate. */
2534 comp_code
= swap_tree_comparison (TREE_CODE (cond
));
2535 val
= TREE_OPERAND (cond
, 0);
2539 /* The comparison is of the form NAME COMP VAL, so the
2540 comparison code remains unchanged. */
2541 comp_code
= TREE_CODE (cond
);
2542 val
= TREE_OPERAND (cond
, 1);
2545 /* If we are inserting the assertion on the ELSE edge, we
2546 need to invert the sign comparison. */
2548 comp_code
= invert_tree_comparison (comp_code
, 0);
2550 /* Do not register always-false predicates. FIXME, this
2551 works around a limitation in fold() when dealing with
2552 enumerations. Given 'enum { N1, N2 } x;', fold will not
2553 fold 'if (x > N2)' to 'if (0)'. */
2554 if ((comp_code
== GT_EXPR
|| comp_code
== LT_EXPR
)
2555 && (INTEGRAL_TYPE_P (TREE_TYPE (val
))
2556 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (val
))))
2558 tree min
= TYPE_MIN_VALUE (TREE_TYPE (val
));
2559 tree max
= TYPE_MAX_VALUE (TREE_TYPE (val
));
2561 if (comp_code
== GT_EXPR
&& compare_values (val
, max
) == 0)
2564 if (comp_code
== LT_EXPR
&& compare_values (val
, min
) == 0)
2571 /* FIXME. Handle SWITCH_EXPR. */
2575 register_new_assert_for (name
, comp_code
, val
, NULL
, e
, si
);
2580 static bool find_assert_locations (basic_block bb
);
2582 /* Determine whether the outgoing edges of BB should receive an
2583 ASSERT_EXPR for each of the operands of BB's last statement. The
2584 last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2586 If any of the sub-graphs rooted at BB have an interesting use of
2587 the predicate operands, an assert location node is added to the
2588 list of assertions for the corresponding operands. */
2591 find_conditional_asserts (basic_block bb
)
2594 block_stmt_iterator last_si
;
2600 need_assert
= false;
2601 last_si
= bsi_last (bb
);
2602 last
= bsi_stmt (last_si
);
2604 /* Look for uses of the operands in each of the sub-graphs
2605 rooted at BB. We need to check each of the outgoing edges
2606 separately, so that we know what kind of ASSERT_EXPR to
2608 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2613 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
2614 Otherwise, when we finish traversing each of the sub-graphs, we
2615 won't know whether the variables were found in the sub-graphs or
2616 if they had been found in a block upstream from BB. */
2617 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
2618 RESET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
2620 /* Traverse the strictly dominated sub-graph rooted at E->DEST
2621 to determine if any of the operands in the conditional
2622 predicate are used. */
2624 need_assert
|= find_assert_locations (e
->dest
);
2626 /* Register the necessary assertions for each operand in the
2627 conditional predicate. */
2628 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
2629 need_assert
|= register_edge_assert_for (op
, e
, last_si
);
2632 /* Finally, indicate that we have found the operands in the
2634 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
2635 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
2641 /* Traverse all the statements in block BB looking for statements that
2642 may generate useful assertions for the SSA names in their operand.
2643 If a statement produces a useful assertion A for name N_i, then the
2644 list of assertions already generated for N_i is scanned to
2645 determine if A is actually needed.
2647 If N_i already had the assertion A at a location dominating the
2648 current location, then nothing needs to be done. Otherwise, the
2649 new location for A is recorded instead.
2651 1- For every statement S in BB, all the variables used by S are
2652 added to bitmap FOUND_IN_SUBGRAPH.
2654 2- If statement S uses an operand N in a way that exposes a known
2655 value range for N, then if N was not already generated by an
2656 ASSERT_EXPR, create a new assert location for N. For instance,
2657 if N is a pointer and the statement dereferences it, we can
2658 assume that N is not NULL.
2660 3- COND_EXPRs are a special case of #2. We can derive range
2661 information from the predicate but need to insert different
2662 ASSERT_EXPRs for each of the sub-graphs rooted at the
2663 conditional block. If the last statement of BB is a conditional
2664 expression of the form 'X op Y', then
2666 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
2668 b) If the conditional is the only entry point to the sub-graph
2669 corresponding to the THEN_CLAUSE, recurse into it. On
2670 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
2671 an ASSERT_EXPR is added for the corresponding variable.
2673 c) Repeat step (b) on the ELSE_CLAUSE.
2675 d) Mark X and Y in FOUND_IN_SUBGRAPH.
2684 In this case, an assertion on the THEN clause is useful to
2685 determine that 'a' is always 9 on that edge. However, an assertion
2686 on the ELSE clause would be unnecessary.
2688 4- If BB does not end in a conditional expression, then we recurse
2689 into BB's dominator children.
2691 At the end of the recursive traversal, every SSA name will have a
2692 list of locations where ASSERT_EXPRs should be added. When a new
2693 location for name N is found, it is registered by calling
2694 register_new_assert_for. That function keeps track of all the
2695 registered assertions to prevent adding unnecessary assertions.
2696 For instance, if a pointer P_4 is dereferenced more than once in a
2697 dominator tree, only the location dominating all the dereference of
2698 P_4 will receive an ASSERT_EXPR.
2700 If this function returns true, then it means that there are names
2701 for which we need to generate ASSERT_EXPRs. Those assertions are
2702 inserted by process_assert_insertions.
2704 TODO. Handle SWITCH_EXPR. */
2707 find_assert_locations (basic_block bb
)
2709 block_stmt_iterator si
;
2714 if (TEST_BIT (blocks_visited
, bb
->index
))
2717 SET_BIT (blocks_visited
, bb
->index
);
2719 need_assert
= false;
2721 /* Traverse all PHI nodes in BB marking used operands. */
2722 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
2724 use_operand_p arg_p
;
2727 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_USE
)
2729 tree arg
= USE_FROM_PTR (arg_p
);
2730 if (TREE_CODE (arg
) == SSA_NAME
)
2732 gcc_assert (is_gimple_reg (PHI_RESULT (phi
)));
2733 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (arg
));
2738 /* Traverse all the statements in BB marking used names and looking
2739 for statements that may infer assertions for their used operands. */
2741 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
2746 stmt
= bsi_stmt (si
);
2748 /* See if we can derive an assertion for any of STMT's operands. */
2749 FOR_EACH_SSA_TREE_OPERAND (op
, stmt
, i
, SSA_OP_USE
)
2752 enum tree_code comp_code
;
2754 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
2755 the sub-graph of a conditional block, when we return from
2756 this recursive walk, our parent will use the
2757 FOUND_IN_SUBGRAPH bitset to determine if one of the
2758 operands it was looking for was present in the sub-graph. */
2759 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
2761 /* If OP is used only once, namely in this STMT, don't
2762 bother creating an ASSERT_EXPR for it. Such an
2763 ASSERT_EXPR would do nothing but increase compile time.
2764 Experiments show that with this simple check, we can save
2765 more than 20% of ASSERT_EXPRs. */
2766 if (has_single_use (op
))
2769 /* If OP is used in such a way that we can infer a value
2770 range for it, and we don't find a previous assertion for
2771 it, create a new assertion location node for OP. */
2772 if (infer_value_range (stmt
, op
, &comp_code
, &value
))
2774 register_new_assert_for (op
, comp_code
, value
, bb
, NULL
, si
);
2779 /* Remember the last statement of the block. */
2783 /* If BB's last statement is a conditional expression
2784 involving integer operands, recurse into each of the sub-graphs
2785 rooted at BB to determine if we need to add ASSERT_EXPRs. */
2787 && TREE_CODE (last
) == COND_EXPR
2788 && !fp_predicate (COND_EXPR_COND (last
))
2789 && !ZERO_SSA_OPERANDS (last
, SSA_OP_USE
))
2790 need_assert
|= find_conditional_asserts (bb
);
2792 /* Recurse into the dominator children of BB. */
2793 for (son
= first_dom_son (CDI_DOMINATORS
, bb
);
2795 son
= next_dom_son (CDI_DOMINATORS
, son
))
2796 need_assert
|= find_assert_locations (son
);
2802 /* Create an ASSERT_EXPR for NAME and insert it in the location
2803 indicated by LOC. Return true if we made any edge insertions. */
2806 process_assert_insertions_for (tree name
, assert_locus_t loc
)
2808 /* Build the comparison expression NAME_i COMP_CODE VAL. */
2809 tree stmt
, cond
, assert_expr
;
2813 cond
= build2 (loc
->comp_code
, boolean_type_node
, name
, loc
->val
);
2814 assert_expr
= build_assert_expr_for (cond
, name
);
2818 /* We have been asked to insert the assertion on an edge. This
2819 is used only by COND_EXPR and SWITCH_EXPR assertions. */
2820 #if defined ENABLE_CHECKING
2821 gcc_assert (TREE_CODE (bsi_stmt (loc
->si
)) == COND_EXPR
2822 || TREE_CODE (bsi_stmt (loc
->si
)) == SWITCH_EXPR
);
2825 bsi_insert_on_edge (loc
->e
, assert_expr
);
2829 /* Otherwise, we can insert right after LOC->SI iff the
2830 statement must not be the last statement in the block. */
2831 stmt
= bsi_stmt (loc
->si
);
2832 if (!stmt_ends_bb_p (stmt
))
2834 bsi_insert_after (&loc
->si
, assert_expr
, BSI_SAME_STMT
);
2838 /* If STMT must be the last statement in BB, we can only insert new
2839 assertions on the non-abnormal edge out of BB. Note that since
2840 STMT is not control flow, there may only be one non-abnormal edge
2842 FOR_EACH_EDGE (e
, ei
, loc
->bb
->succs
)
2843 if (!(e
->flags
& EDGE_ABNORMAL
))
2845 bsi_insert_on_edge (e
, assert_expr
);
2853 /* Process all the insertions registered for every name N_i registered
2854 in NEED_ASSERT_FOR. The list of assertions to be inserted are
2855 found in ASSERTS_FOR[i]. */
2858 process_assert_insertions (void)
2862 bool update_edges_p
= false;
2863 int num_asserts
= 0;
2865 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2866 dump_all_asserts (dump_file
);
2868 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
2870 assert_locus_t loc
= asserts_for
[i
];
2875 assert_locus_t next
= loc
->next
;
2876 update_edges_p
|= process_assert_insertions_for (ssa_name (i
), loc
);
2884 bsi_commit_edge_inserts ();
2886 if (dump_file
&& (dump_flags
& TDF_STATS
))
2887 fprintf (dump_file
, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
2892 /* Traverse the flowgraph looking for conditional jumps to insert range
2893 expressions. These range expressions are meant to provide information
2894 to optimizations that need to reason in terms of value ranges. They
2895 will not be expanded into RTL. For instance, given:
2904 this pass will transform the code into:
2910 x = ASSERT_EXPR <x, x < y>
2915 y = ASSERT_EXPR <y, x <= y>
2919 The idea is that once copy and constant propagation have run, other
2920 optimizations will be able to determine what ranges of values can 'x'
2921 take in different paths of the code, simply by checking the reaching
2922 definition of 'x'. */
2925 insert_range_assertions (void)
2931 found_in_subgraph
= sbitmap_alloc (num_ssa_names
);
2932 sbitmap_zero (found_in_subgraph
);
2934 blocks_visited
= sbitmap_alloc (last_basic_block
);
2935 sbitmap_zero (blocks_visited
);
2937 need_assert_for
= BITMAP_ALLOC (NULL
);
2938 asserts_for
= xmalloc (num_ssa_names
* sizeof (assert_locus_t
));
2939 memset (asserts_for
, 0, num_ssa_names
* sizeof (assert_locus_t
));
2941 calculate_dominance_info (CDI_DOMINATORS
);
2943 update_ssa_p
= false;
2944 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
2945 if (find_assert_locations (e
->dest
))
2946 update_ssa_p
= true;
2950 process_assert_insertions ();
2951 update_ssa (TODO_update_ssa_no_phi
);
2954 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2956 fprintf (dump_file
, "\nSSA form after inserting ASSERT_EXPRs\n");
2957 dump_function_to_file (current_function_decl
, dump_file
, dump_flags
);
2960 sbitmap_free (found_in_subgraph
);
2962 BITMAP_FREE (need_assert_for
);
2966 /* Convert range assertion expressions into the implied copies and
2967 copy propagate away the copies. Doing the trivial copy propagation
2968 here avoids the need to run the full copy propagation pass after
2971 FIXME, this will eventually lead to copy propagation removing the
2972 names that had useful range information attached to them. For
2973 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
2974 then N_i will have the range [3, +INF].
2976 However, by converting the assertion into the implied copy
2977 operation N_i = N_j, we will then copy-propagate N_j into the uses
2978 of N_i and lose the range information. We may want to hold on to
2979 ASSERT_EXPRs a little while longer as the ranges could be used in
2980 things like jump threading.
2982 The problem with keeping ASSERT_EXPRs around is that passes after
2983 VRP need to handle them appropriately.
2985 Another approach would be to make the range information a first
2986 class property of the SSA_NAME so that it can be queried from
2987 any pass. This is made somewhat more complex by the need for
2988 multiple ranges to be associated with one SSA_NAME. */
2991 remove_range_assertions (void)
2994 block_stmt_iterator si
;
2996 /* Note that the BSI iterator bump happens at the bottom of the
2997 loop and no bump is necessary if we're removing the statement
2998 referenced by the current BSI. */
3000 for (si
= bsi_start (bb
); !bsi_end_p (si
);)
3002 tree stmt
= bsi_stmt (si
);
3004 if (TREE_CODE (stmt
) == MODIFY_EXPR
3005 && TREE_CODE (TREE_OPERAND (stmt
, 1)) == ASSERT_EXPR
)
3007 tree rhs
= TREE_OPERAND (stmt
, 1);
3008 tree cond
= fold (ASSERT_EXPR_COND (rhs
));
3009 use_operand_p use_p
;
3010 imm_use_iterator iter
;
3012 gcc_assert (cond
!= boolean_false_node
);
3013 TREE_OPERAND (stmt
, 1) = ASSERT_EXPR_VAR (rhs
);
3016 /* The statement is now a copy. Propagate the RHS into
3017 every use of the LHS. */
3018 FOR_EACH_IMM_USE_SAFE (use_p
, iter
, TREE_OPERAND (stmt
, 0))
3020 SET_USE (use_p
, ASSERT_EXPR_VAR (rhs
));
3021 update_stmt (USE_STMT (use_p
));
3024 /* And finally, remove the copy, it is not needed. */
3031 sbitmap_free (blocks_visited
);
3035 /* Return true if STMT is interesting for VRP. */
3038 stmt_interesting_for_vrp (tree stmt
)
3040 if (TREE_CODE (stmt
) == PHI_NODE
3041 && is_gimple_reg (PHI_RESULT (stmt
))
3042 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))
3043 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))))
3045 else if (TREE_CODE (stmt
) == MODIFY_EXPR
)
3047 tree lhs
= TREE_OPERAND (stmt
, 0);
3049 if (TREE_CODE (lhs
) == SSA_NAME
3050 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
3051 || POINTER_TYPE_P (TREE_TYPE (lhs
)))
3052 && ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
3055 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
3062 /* Initialize local data structures for VRP. */
3065 vrp_initialize (void)
3069 vr_value
= xmalloc (num_ssa_names
* sizeof (value_range_t
*));
3070 memset (vr_value
, 0, num_ssa_names
* sizeof (value_range_t
*));
3074 block_stmt_iterator si
;
3077 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3079 if (!stmt_interesting_for_vrp (phi
))
3081 tree lhs
= PHI_RESULT (phi
);
3082 set_value_range_to_varying (get_value_range (lhs
));
3083 DONT_SIMULATE_AGAIN (phi
) = true;
3086 DONT_SIMULATE_AGAIN (phi
) = false;
3089 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
3091 tree stmt
= bsi_stmt (si
);
3093 if (!stmt_interesting_for_vrp (stmt
))
3097 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, i
, SSA_OP_DEF
)
3098 set_value_range_to_varying (get_value_range (def
));
3099 DONT_SIMULATE_AGAIN (stmt
) = true;
3103 DONT_SIMULATE_AGAIN (stmt
) = false;
3110 /* Visit assignment STMT. If it produces an interesting range, record
3111 the SSA name in *OUTPUT_P. */
3113 static enum ssa_prop_result
3114 vrp_visit_assignment (tree stmt
, tree
*output_p
)
3119 lhs
= TREE_OPERAND (stmt
, 0);
3120 rhs
= TREE_OPERAND (stmt
, 1);
3122 /* We only keep track of ranges in integral and pointer types. */
3123 if (TREE_CODE (lhs
) == SSA_NAME
3124 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
3125 || POINTER_TYPE_P (TREE_TYPE (lhs
))))
3128 value_range_t new_vr
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
3130 extract_range_from_expr (&new_vr
, rhs
);
3132 /* If STMT is inside a loop, we may be able to know something
3133 else about the range of LHS by examining scalar evolution
3135 if (cfg_loops
&& (l
= loop_containing_stmt (stmt
)))
3136 adjust_range_with_scev (&new_vr
, l
, stmt
, lhs
);
3138 if (update_value_range (lhs
, &new_vr
))
3142 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3144 fprintf (dump_file
, "Found new range for ");
3145 print_generic_expr (dump_file
, lhs
, 0);
3146 fprintf (dump_file
, ": ");
3147 dump_value_range (dump_file
, &new_vr
);
3148 fprintf (dump_file
, "\n\n");
3151 if (new_vr
.type
== VR_VARYING
)
3152 return SSA_PROP_VARYING
;
3154 return SSA_PROP_INTERESTING
;
3157 return SSA_PROP_NOT_INTERESTING
;
3160 /* Every other statement produces no useful ranges. */
3161 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
3162 set_value_range_to_varying (get_value_range (def
));
3164 return SSA_PROP_VARYING
;
3168 /* Compare all the value ranges for names equivalent to VAR with VAL
3169 using comparison code COMP. Return the same value returned by
3170 compare_range_with_value. */
3173 compare_name_with_value (enum tree_code comp
, tree var
, tree val
)
3180 t
= retval
= NULL_TREE
;
3182 /* Get the set of equivalences for VAR. */
3183 e
= get_value_range (var
)->equiv
;
3185 /* Add VAR to its own set of equivalences so that VAR's value range
3186 is processed by this loop (otherwise, we would have to replicate
3187 the body of the loop just to check VAR's value range). */
3188 bitmap_set_bit (e
, SSA_NAME_VERSION (var
));
3190 EXECUTE_IF_SET_IN_BITMAP (e
, 0, i
, bi
)
3192 value_range_t equiv_vr
= *(vr_value
[i
]);
3194 /* If name N_i does not have a valid range, use N_i as its own
3195 range. This allows us to compare against names that may
3196 have N_i in their ranges. */
3197 if (equiv_vr
.type
== VR_VARYING
|| equiv_vr
.type
== VR_UNDEFINED
)
3199 equiv_vr
.type
= VR_RANGE
;
3200 equiv_vr
.min
= ssa_name (i
);
3201 equiv_vr
.max
= ssa_name (i
);
3204 t
= compare_range_with_value (comp
, &equiv_vr
, val
);
3207 /* All the ranges should compare the same against VAL. */
3208 gcc_assert (retval
== NULL
|| t
== retval
);
3213 /* Remove VAR from its own equivalence set. */
3214 bitmap_clear_bit (e
, SSA_NAME_VERSION (var
));
3219 /* We couldn't find a non-NULL value for the predicate. */
3224 /* Given a comparison code COMP and names N1 and N2, compare all the
3225 ranges equivalent to N1 against all the ranges equivalent to N2
3226 to determine the value of N1 COMP N2. Return the same value
3227 returned by compare_ranges. */
3230 compare_names (enum tree_code comp
, tree n1
, tree n2
)
3234 bitmap_iterator bi1
, bi2
;
3237 /* Compare the ranges of every name equivalent to N1 against the
3238 ranges of every name equivalent to N2. */
3239 e1
= get_value_range (n1
)->equiv
;
3240 e2
= get_value_range (n2
)->equiv
;
3242 /* Add N1 and N2 to their own set of equivalences to avoid
3243 duplicating the body of the loop just to check N1 and N2
3245 bitmap_set_bit (e1
, SSA_NAME_VERSION (n1
));
3246 bitmap_set_bit (e2
, SSA_NAME_VERSION (n2
));
3248 /* If the equivalence sets have a common intersection, then the two
3249 names can be compared without checking their ranges. */
3250 if (bitmap_intersect_p (e1
, e2
))
3252 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3253 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3255 return (comp
== EQ_EXPR
|| comp
== GE_EXPR
|| comp
== LE_EXPR
)
3257 : boolean_false_node
;
3260 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3261 N2 to their own set of equivalences to avoid duplicating the body
3262 of the loop just to check N1 and N2 ranges. */
3263 EXECUTE_IF_SET_IN_BITMAP (e1
, 0, i1
, bi1
)
3265 value_range_t vr1
= *(vr_value
[i1
]);
3267 /* If the range is VARYING or UNDEFINED, use the name itself. */
3268 if (vr1
.type
== VR_VARYING
|| vr1
.type
== VR_UNDEFINED
)
3270 vr1
.type
= VR_RANGE
;
3271 vr1
.min
= ssa_name (i1
);
3272 vr1
.max
= ssa_name (i1
);
3275 t
= retval
= NULL_TREE
;
3276 EXECUTE_IF_SET_IN_BITMAP (e2
, 0, i2
, bi2
)
3278 value_range_t vr2
= *(vr_value
[i2
]);
3280 if (vr2
.type
== VR_VARYING
|| vr2
.type
== VR_UNDEFINED
)
3282 vr2
.type
= VR_RANGE
;
3283 vr2
.min
= ssa_name (i2
);
3284 vr2
.max
= ssa_name (i2
);
3287 t
= compare_ranges (comp
, &vr1
, &vr2
);
3290 /* All the ranges in the equivalent sets should compare
3292 gcc_assert (retval
== NULL
|| t
== retval
);
3299 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3300 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3305 /* None of the equivalent ranges are useful in computing this
3307 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3308 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3313 /* Given a conditional predicate COND, try to determine if COND yields
3314 true or false based on the value ranges of its operands. Return
3315 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3316 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3317 NULL if the conditional cannot be evaluated at compile time.
3319 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3320 the operands in COND are used when trying to compute its value.
3321 This is only used during final substitution. During propagation,
3322 we only check the range of each variable and not its equivalents. */
3325 vrp_evaluate_conditional (tree cond
, bool use_equiv_p
)
3327 gcc_assert (TREE_CODE (cond
) == SSA_NAME
3328 || TREE_CODE_CLASS (TREE_CODE (cond
)) == tcc_comparison
);
3330 if (TREE_CODE (cond
) == SSA_NAME
)
3336 retval
= compare_name_with_value (NE_EXPR
, cond
, boolean_false_node
);
3339 value_range_t
*vr
= get_value_range (cond
);
3340 retval
= compare_range_with_value (NE_EXPR
, vr
, boolean_false_node
);
3343 /* If COND has a known boolean range, return it. */
3347 /* Otherwise, if COND has a symbolic range of exactly one value,
3349 vr
= get_value_range (cond
);
3350 if (vr
->type
== VR_RANGE
&& vr
->min
== vr
->max
)
3355 tree op0
= TREE_OPERAND (cond
, 0);
3356 tree op1
= TREE_OPERAND (cond
, 1);
3358 /* We only deal with integral and pointer types. */
3359 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
3360 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
3365 if (TREE_CODE (op0
) == SSA_NAME
&& TREE_CODE (op1
) == SSA_NAME
)
3366 return compare_names (TREE_CODE (cond
), op0
, op1
);
3367 else if (TREE_CODE (op0
) == SSA_NAME
)
3368 return compare_name_with_value (TREE_CODE (cond
), op0
, op1
);
3369 else if (TREE_CODE (op1
) == SSA_NAME
)
3370 return compare_name_with_value (
3371 swap_tree_comparison (TREE_CODE (cond
)), op1
, op0
);
3375 value_range_t
*vr0
, *vr1
;
3377 vr0
= (TREE_CODE (op0
) == SSA_NAME
) ? get_value_range (op0
) : NULL
;
3378 vr1
= (TREE_CODE (op1
) == SSA_NAME
) ? get_value_range (op1
) : NULL
;
3381 return compare_ranges (TREE_CODE (cond
), vr0
, vr1
);
3382 else if (vr0
&& vr1
== NULL
)
3383 return compare_range_with_value (TREE_CODE (cond
), vr0
, op1
);
3384 else if (vr0
== NULL
&& vr1
)
3385 return compare_range_with_value (
3386 swap_tree_comparison (TREE_CODE (cond
)), vr1
, op0
);
3390 /* Anything else cannot be computed statically. */
3395 /* Visit conditional statement STMT. If we can determine which edge
3396 will be taken out of STMT's basic block, record it in
3397 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3398 SSA_PROP_VARYING. */
3400 static enum ssa_prop_result
3401 vrp_visit_cond_stmt (tree stmt
, edge
*taken_edge_p
)
3405 *taken_edge_p
= NULL
;
3407 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3408 add ASSERT_EXPRs for them. */
3409 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
3410 return SSA_PROP_VARYING
;
3412 cond
= COND_EXPR_COND (stmt
);
3414 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3419 fprintf (dump_file
, "\nVisiting conditional with predicate: ");
3420 print_generic_expr (dump_file
, cond
, 0);
3421 fprintf (dump_file
, "\nWith known ranges\n");
3423 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, i
, SSA_OP_USE
)
3425 fprintf (dump_file
, "\t");
3426 print_generic_expr (dump_file
, use
, 0);
3427 fprintf (dump_file
, ": ");
3428 dump_value_range (dump_file
, vr_value
[SSA_NAME_VERSION (use
)]);
3431 fprintf (dump_file
, "\n");
3434 /* Compute the value of the predicate COND by checking the known
3435 ranges of each of its operands.
3437 Note that we cannot evaluate all the equivalent ranges here
3438 because those ranges may not yet be final and with the current
3439 propagation strategy, we cannot determine when the value ranges
3440 of the names in the equivalence set have changed.
3442 For instance, given the following code fragment
3446 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3450 Assume that on the first visit to i_14, i_5 has the temporary
3451 range [8, 8] because the second argument to the PHI function is
3452 not yet executable. We derive the range ~[0, 0] for i_14 and the
3453 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3454 the first time, since i_14 is equivalent to the range [8, 8], we
3455 determine that the predicate is always false.
3457 On the next round of propagation, i_13 is determined to be
3458 VARYING, which causes i_5 to drop down to VARYING. So, another
3459 visit to i_14 is scheduled. In this second visit, we compute the
3460 exact same range and equivalence set for i_14, namely ~[0, 0] and
3461 { i_5 }. But we did not have the previous range for i_5
3462 registered, so vrp_visit_assignment thinks that the range for
3463 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3464 is not visited again, which stops propagation from visiting
3465 statements in the THEN clause of that if().
3467 To properly fix this we would need to keep the previous range
3468 value for the names in the equivalence set. This way we would've
3469 discovered that from one visit to the other i_5 changed from
3470 range [8, 8] to VR_VARYING.
3472 However, fixing this apparent limitation may not be worth the
3473 additional checking. Testing on several code bases (GCC, DLV,
3474 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3475 4 more predicates folded in SPEC. */
3476 val
= vrp_evaluate_conditional (cond
, false);
3478 *taken_edge_p
= find_taken_edge (bb_for_stmt (stmt
), val
);
3480 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3482 fprintf (dump_file
, "\nPredicate evaluates to: ");
3483 if (val
== NULL_TREE
)
3484 fprintf (dump_file
, "DON'T KNOW\n");
3486 print_generic_stmt (dump_file
, val
, 0);
3489 return (*taken_edge_p
) ? SSA_PROP_INTERESTING
: SSA_PROP_VARYING
;
3493 /* Evaluate statement STMT. If the statement produces a useful range,
3494 return SSA_PROP_INTERESTING and record the SSA name with the
3495 interesting range into *OUTPUT_P.
3497 If STMT is a conditional branch and we can determine its truth
3498 value, the taken edge is recorded in *TAKEN_EDGE_P.
3500 If STMT produces a varying value, return SSA_PROP_VARYING. */
3502 static enum ssa_prop_result
3503 vrp_visit_stmt (tree stmt
, edge
*taken_edge_p
, tree
*output_p
)
3509 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3511 fprintf (dump_file
, "\nVisiting statement:\n");
3512 print_generic_stmt (dump_file
, stmt
, dump_flags
);
3513 fprintf (dump_file
, "\n");
3516 ann
= stmt_ann (stmt
);
3517 if (TREE_CODE (stmt
) == MODIFY_EXPR
3518 && ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
3519 return vrp_visit_assignment (stmt
, output_p
);
3520 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
3521 return vrp_visit_cond_stmt (stmt
, taken_edge_p
);
3523 /* All other statements produce nothing of interest for VRP, so mark
3524 their outputs varying and prevent further simulation. */
3525 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
3526 set_value_range_to_varying (get_value_range (def
));
3528 return SSA_PROP_VARYING
;
3532 /* Meet operation for value ranges. Given two value ranges VR0 and
3533 VR1, store in VR0 the result of meeting VR0 and VR1.
3535 The meeting rules are as follows:
3537 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
3539 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
3540 union of VR0 and VR1. */
3543 vrp_meet (value_range_t
*vr0
, value_range_t
*vr1
)
3545 if (vr0
->type
== VR_UNDEFINED
)
3547 copy_value_range (vr0
, vr1
);
3551 if (vr1
->type
== VR_UNDEFINED
)
3553 /* Nothing to do. VR0 already has the resulting range. */
3557 if (vr0
->type
== VR_VARYING
)
3559 /* Nothing to do. VR0 already has the resulting range. */
3563 if (vr1
->type
== VR_VARYING
)
3565 set_value_range_to_varying (vr0
);
3569 if (vr0
->type
== VR_RANGE
&& vr1
->type
== VR_RANGE
)
3571 /* If VR0 and VR1 have a non-empty intersection, compute the
3572 union of both ranges. */
3573 if (value_ranges_intersect_p (vr0
, vr1
))
3578 /* The lower limit of the new range is the minimum of the
3579 two ranges. If they cannot be compared, the result is
3581 cmp
= compare_values (vr0
->min
, vr1
->min
);
3582 if (cmp
== 0 || cmp
== 1)
3588 set_value_range_to_varying (vr0
);
3592 /* Similarly, the upper limit of the new range is the
3593 maximum of the two ranges. If they cannot be compared,
3594 the result is VARYING. */
3595 cmp
= compare_values (vr0
->max
, vr1
->max
);
3596 if (cmp
== 0 || cmp
== -1)
3602 set_value_range_to_varying (vr0
);
3606 /* The resulting set of equivalences is the intersection of
3608 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
3609 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
3610 else if (vr0
->equiv
&& !vr1
->equiv
)
3611 bitmap_clear (vr0
->equiv
);
3613 set_value_range (vr0
, vr0
->type
, min
, max
, vr0
->equiv
);
3618 else if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
3620 /* Two anti-ranges meet only if they are both identical. */
3621 if (compare_values (vr0
->min
, vr1
->min
) == 0
3622 && compare_values (vr0
->max
, vr1
->max
) == 0
3623 && compare_values (vr0
->min
, vr0
->max
) == 0)
3625 /* The resulting set of equivalences is the intersection of
3627 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
3628 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
3629 else if (vr0
->equiv
&& !vr1
->equiv
)
3630 bitmap_clear (vr0
->equiv
);
3635 else if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
3637 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
3638 meet only if the ranges have an empty intersection. The
3639 result of the meet operation is the anti-range. */
3640 if (!symbolic_range_p (vr0
)
3641 && !symbolic_range_p (vr1
)
3642 && !value_ranges_intersect_p (vr0
, vr1
))
3644 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
3645 set. We need to compute the intersection of the two
3646 equivalence sets. */
3647 if (vr1
->type
== VR_ANTI_RANGE
)
3648 set_value_range (vr0
, vr1
->type
, vr1
->min
, vr1
->max
, vr0
->equiv
);
3650 /* The resulting set of equivalences is the intersection of
3652 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
3653 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
3654 else if (vr0
->equiv
&& !vr1
->equiv
)
3655 bitmap_clear (vr0
->equiv
);
3666 /* The two range VR0 and VR1 do not meet. Before giving up and
3667 setting the result to VARYING, see if we can at least derive a
3668 useful anti-range. FIXME, all this nonsense about distinguishing
3669 anti-ranges from ranges is necessary because of the odd
3670 semantics of range_includes_zero_p and friends. */
3671 if (!symbolic_range_p (vr0
)
3672 && ((vr0
->type
== VR_RANGE
&& !range_includes_zero_p (vr0
))
3673 || (vr0
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr0
)))
3674 && !symbolic_range_p (vr1
)
3675 && ((vr1
->type
== VR_RANGE
&& !range_includes_zero_p (vr1
))
3676 || (vr1
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr1
))))
3678 set_value_range_to_nonnull (vr0
, TREE_TYPE (vr0
->min
));
3680 /* Since this meet operation did not result from the meeting of
3681 two equivalent names, VR0 cannot have any equivalences. */
3683 bitmap_clear (vr0
->equiv
);
3686 set_value_range_to_varying (vr0
);
3690 /* Visit all arguments for PHI node PHI that flow through executable
3691 edges. If a valid value range can be derived from all the incoming
3692 value ranges, set a new range for the LHS of PHI. */
3694 static enum ssa_prop_result
3695 vrp_visit_phi_node (tree phi
)
3698 tree lhs
= PHI_RESULT (phi
);
3699 value_range_t
*lhs_vr
= get_value_range (lhs
);
3700 value_range_t vr_result
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
3702 copy_value_range (&vr_result
, lhs_vr
);
3704 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3706 fprintf (dump_file
, "\nVisiting PHI node: ");
3707 print_generic_expr (dump_file
, phi
, dump_flags
);
3710 for (i
= 0; i
< PHI_NUM_ARGS (phi
); i
++)
3712 edge e
= PHI_ARG_EDGE (phi
, i
);
3714 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3717 "\n Argument #%d (%d -> %d %sexecutable)\n",
3718 i
, e
->src
->index
, e
->dest
->index
,
3719 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
3722 if (e
->flags
& EDGE_EXECUTABLE
)
3724 tree arg
= PHI_ARG_DEF (phi
, i
);
3725 value_range_t vr_arg
;
3727 if (TREE_CODE (arg
) == SSA_NAME
)
3728 vr_arg
= *(get_value_range (arg
));
3731 vr_arg
.type
= VR_RANGE
;
3734 vr_arg
.equiv
= NULL
;
3737 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3739 fprintf (dump_file
, "\t");
3740 print_generic_expr (dump_file
, arg
, dump_flags
);
3741 fprintf (dump_file
, "\n\tValue: ");
3742 dump_value_range (dump_file
, &vr_arg
);
3743 fprintf (dump_file
, "\n");
3746 vrp_meet (&vr_result
, &vr_arg
);
3748 if (vr_result
.type
== VR_VARYING
)
3753 if (vr_result
.type
== VR_VARYING
)
3756 /* To prevent infinite iterations in the algorithm, derive ranges
3757 when the new value is slightly bigger or smaller than the
3759 if (lhs_vr
->type
== VR_RANGE
&& vr_result
.type
== VR_RANGE
)
3761 if (!POINTER_TYPE_P (TREE_TYPE (lhs
)))
3763 int cmp_min
= compare_values (lhs_vr
->min
, vr_result
.min
);
3764 int cmp_max
= compare_values (lhs_vr
->max
, vr_result
.max
);
3766 /* If the new minimum is smaller or larger than the previous
3767 one, go all the way to -INF. In the first case, to avoid
3768 iterating millions of times to reach -INF, and in the
3769 other case to avoid infinite bouncing between different
3771 if (cmp_min
> 0 || cmp_min
< 0)
3772 vr_result
.min
= TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
));
3774 /* Similarly, if the new maximum is smaller or larger than
3775 the previous one, go all the way to +INF. */
3776 if (cmp_max
< 0 || cmp_max
> 0)
3777 vr_result
.max
= TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
));
3779 /* If we ended up with a (-INF, +INF) range, set it to
3781 if (vr_result
.min
== TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
))
3782 && vr_result
.max
== TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
)))
3787 /* If the new range is different than the previous value, keep
3789 if (update_value_range (lhs
, &vr_result
))
3790 return SSA_PROP_INTERESTING
;
3792 /* Nothing changed, don't add outgoing edges. */
3793 return SSA_PROP_NOT_INTERESTING
;
3795 /* No match found. Set the LHS to VARYING. */
3797 set_value_range_to_varying (lhs_vr
);
3798 return SSA_PROP_VARYING
;
3801 /* Simplify a division or modulo operator to a right shift or
3802 bitwise and if the first operand is unsigned or is greater
3803 than zero and the second operand is an exact power of two. */
3806 simplify_div_or_mod_using_ranges (tree stmt
, tree rhs
, enum tree_code rhs_code
)
3809 tree op
= TREE_OPERAND (rhs
, 0);
3810 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
3812 if (TYPE_UNSIGNED (TREE_TYPE (op
)))
3814 val
= integer_one_node
;
3818 val
= compare_range_with_value (GT_EXPR
, vr
, integer_zero_node
);
3821 if (val
&& integer_onep (val
))
3824 tree op0
= TREE_OPERAND (rhs
, 0);
3825 tree op1
= TREE_OPERAND (rhs
, 1);
3827 if (rhs_code
== TRUNC_DIV_EXPR
)
3829 t
= build_int_cst (NULL_TREE
, tree_log2 (op1
));
3830 t
= build2 (RSHIFT_EXPR
, TREE_TYPE (op0
), op0
, t
);
3834 t
= build_int_cst (TREE_TYPE (op1
), 1);
3835 t
= int_const_binop (MINUS_EXPR
, op1
, t
, 0);
3836 t
= fold_convert (TREE_TYPE (op0
), t
);
3837 t
= build2 (BIT_AND_EXPR
, TREE_TYPE (op0
), op0
, t
);
3840 TREE_OPERAND (stmt
, 1) = t
;
3845 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
3846 ABS_EXPR. If the operand is <= 0, then simplify the
3847 ABS_EXPR into a NEGATE_EXPR. */
3850 simplify_abs_using_ranges (tree stmt
, tree rhs
)
3853 tree op
= TREE_OPERAND (rhs
, 0);
3854 tree type
= TREE_TYPE (op
);
3855 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
3857 if (TYPE_UNSIGNED (type
))
3859 val
= integer_zero_node
;
3863 val
= compare_range_with_value (LE_EXPR
, vr
, integer_zero_node
);
3866 val
= compare_range_with_value (GE_EXPR
, vr
, integer_zero_node
);
3870 if (integer_zerop (val
))
3871 val
= integer_one_node
;
3872 else if (integer_onep (val
))
3873 val
= integer_zero_node
;
3878 && (integer_onep (val
) || integer_zerop (val
)))
3882 if (integer_onep (val
))
3883 t
= build1 (NEGATE_EXPR
, TREE_TYPE (op
), op
);
3887 TREE_OPERAND (stmt
, 1) = t
;
3893 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
3894 a known value range VR.
3896 If there is one and only one value which will satisfy the
3897 conditional, then return that value. Else return NULL. */
3900 test_for_singularity (enum tree_code cond_code
, tree op0
,
3901 tree op1
, value_range_t
*vr
)
3906 /* Extract minimum/maximum values which satisfy the
3907 the conditional as it was written. */
3908 if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
3910 min
= TYPE_MIN_VALUE (TREE_TYPE (op0
));
3913 if (cond_code
== LT_EXPR
)
3915 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
3916 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (op0
), max
, one
);
3919 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
3921 max
= TYPE_MAX_VALUE (TREE_TYPE (op0
));
3924 if (cond_code
== GT_EXPR
)
3926 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
3927 max
= fold_build2 (PLUS_EXPR
, TREE_TYPE (op0
), max
, one
);
3931 /* Now refine the minimum and maximum values using any
3932 value range information we have for op0. */
3935 if (compare_values (vr
->min
, min
) == -1)
3939 if (compare_values (vr
->max
, max
) == 1)
3944 /* If the new min/max values have converged to a
3945 single value, then there is only one value which
3946 can satisfy the condition, return that value. */
3947 if (min
== max
&& is_gimple_min_invariant (min
))
3953 /* Simplify a conditional using a relational operator to an equality
3954 test if the range information indicates only one value can satisfy
3955 the original conditional. */
3958 simplify_cond_using_ranges (tree stmt
)
3960 tree cond
= COND_EXPR_COND (stmt
);
3961 tree op0
= TREE_OPERAND (cond
, 0);
3962 tree op1
= TREE_OPERAND (cond
, 1);
3963 enum tree_code cond_code
= TREE_CODE (cond
);
3965 if (cond_code
!= NE_EXPR
3966 && cond_code
!= EQ_EXPR
3967 && TREE_CODE (op0
) == SSA_NAME
3968 && INTEGRAL_TYPE_P (TREE_TYPE (op0
))
3969 && is_gimple_min_invariant (op1
))
3971 value_range_t
*vr
= get_value_range (op0
);
3973 /* If we have range information for OP0, then we might be
3974 able to simplify this conditional. */
3975 if (vr
->type
== VR_RANGE
)
3977 tree
new = test_for_singularity (cond_code
, op0
, op1
, vr
);
3983 fprintf (dump_file
, "Simplified relational ");
3984 print_generic_expr (dump_file
, cond
, 0);
3985 fprintf (dump_file
, " into ");
3988 COND_EXPR_COND (stmt
)
3989 = build2 (EQ_EXPR
, boolean_type_node
, op0
, new);
3994 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
3995 fprintf (dump_file
, "\n");
4001 /* Try again after inverting the condition. We only deal
4002 with integral types here, so no need to worry about
4003 issues with inverting FP comparisons. */
4004 cond_code
= invert_tree_comparison (cond_code
, false);
4005 new = test_for_singularity (cond_code
, op0
, op1
, vr
);
4011 fprintf (dump_file
, "Simplified relational ");
4012 print_generic_expr (dump_file
, cond
, 0);
4013 fprintf (dump_file
, " into ");
4016 COND_EXPR_COND (stmt
)
4017 = build2 (NE_EXPR
, boolean_type_node
, op0
, new);
4022 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
4023 fprintf (dump_file
, "\n");
4032 /* Simplify STMT using ranges if possible. */
4035 simplify_stmt_using_ranges (tree stmt
)
4037 if (TREE_CODE (stmt
) == MODIFY_EXPR
)
4039 tree rhs
= TREE_OPERAND (stmt
, 1);
4040 enum tree_code rhs_code
= TREE_CODE (rhs
);
4042 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
4043 and BIT_AND_EXPR respectively if the first operand is greater
4044 than zero and the second operand is an exact power of two. */
4045 if ((rhs_code
== TRUNC_DIV_EXPR
|| rhs_code
== TRUNC_MOD_EXPR
)
4046 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0)))
4047 && integer_pow2p (TREE_OPERAND (rhs
, 1)))
4048 simplify_div_or_mod_using_ranges (stmt
, rhs
, rhs_code
);
4050 /* Transform ABS (X) into X or -X as appropriate. */
4051 if (rhs_code
== ABS_EXPR
4052 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == SSA_NAME
4053 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0))))
4054 simplify_abs_using_ranges (stmt
, rhs
);
4056 else if (TREE_CODE (stmt
) == COND_EXPR
4057 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt
)))
4059 simplify_cond_using_ranges (stmt
);
4065 /* Traverse all the blocks folding conditionals with known ranges. */
4071 prop_value_t
*single_val_range
;
4072 bool do_value_subst_p
;
4076 fprintf (dump_file
, "\nValue ranges after VRP:\n\n");
4077 dump_all_value_ranges (dump_file
);
4078 fprintf (dump_file
, "\n");
4081 /* We may have ended with ranges that have exactly one value. Those
4082 values can be substituted as any other copy/const propagated
4083 value using substitute_and_fold. */
4084 single_val_range
= xmalloc (num_ssa_names
* sizeof (*single_val_range
));
4085 memset (single_val_range
, 0, num_ssa_names
* sizeof (*single_val_range
));
4087 do_value_subst_p
= false;
4088 for (i
= 0; i
< num_ssa_names
; i
++)
4090 && vr_value
[i
]->type
== VR_RANGE
4091 && vr_value
[i
]->min
== vr_value
[i
]->max
)
4093 single_val_range
[i
].value
= vr_value
[i
]->min
;
4094 do_value_subst_p
= true;
4097 if (!do_value_subst_p
)
4099 /* We found no single-valued ranges, don't waste time trying to
4100 do single value substitution in substitute_and_fold. */
4101 free (single_val_range
);
4102 single_val_range
= NULL
;
4105 substitute_and_fold (single_val_range
, true);
4107 /* Free allocated memory. */
4108 for (i
= 0; i
< num_ssa_names
; i
++)
4111 BITMAP_FREE (vr_value
[i
]->equiv
);
4115 free (single_val_range
);
4120 /* Main entry point to VRP (Value Range Propagation). This pass is
4121 loosely based on J. R. C. Patterson, ``Accurate Static Branch
4122 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
4123 Programming Language Design and Implementation, pp. 67-78, 1995.
4124 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
4126 This is essentially an SSA-CCP pass modified to deal with ranges
4127 instead of constants.
4129 While propagating ranges, we may find that two or more SSA name
4130 have equivalent, though distinct ranges. For instance,
4133 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
4135 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
4139 In the code above, pointer p_5 has range [q_2, q_2], but from the
4140 code we can also determine that p_5 cannot be NULL and, if q_2 had
4141 a non-varying range, p_5's range should also be compatible with it.
4143 These equivalences are created by two expressions: ASSERT_EXPR and
4144 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
4145 result of another assertion, then we can use the fact that p_5 and
4146 p_4 are equivalent when evaluating p_5's range.
4148 Together with value ranges, we also propagate these equivalences
4149 between names so that we can take advantage of information from
4150 multiple ranges when doing final replacement. Note that this
4151 equivalency relation is transitive but not symmetric.
4153 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
4154 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
4155 in contexts where that assertion does not hold (e.g., in line 6).
4157 TODO, the main difference between this pass and Patterson's is that
4158 we do not propagate edge probabilities. We only compute whether
4159 edges can be taken or not. That is, instead of having a spectrum
4160 of jump probabilities between 0 and 1, we only deal with 0, 1 and
4161 DON'T KNOW. In the future, it may be worthwhile to propagate
4162 probabilities to aid branch prediction. */
4167 insert_range_assertions ();
4169 cfg_loops
= loop_optimizer_init (NULL
);
4171 scev_initialize (cfg_loops
);
4174 ssa_propagate (vrp_visit_stmt
, vrp_visit_phi_node
);
4180 loop_optimizer_finalize (cfg_loops
, NULL
);
4181 current_loops
= NULL
;
4184 remove_range_assertions ();
4190 return flag_tree_vrp
!= 0;
4193 struct tree_opt_pass pass_vrp
=
4196 gate_vrp
, /* gate */
4197 execute_vrp
, /* execute */
4200 0, /* static_pass_number */
4201 TV_TREE_VRP
, /* tv_id */
4202 PROP_ssa
| PROP_alias
, /* properties_required */
4203 0, /* properties_provided */
4204 0, /* properties_destroyed */
4205 0, /* todo_flags_start */
4210 | TODO_update_ssa
, /* todo_flags_finish */