1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005, 2006 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
24 #include "coretypes.h"
29 #include "basic-block.h"
30 #include "tree-flow.h"
31 #include "tree-pass.h"
32 #include "tree-dump.h"
34 #include "diagnostic.h"
36 #include "tree-scalar-evolution.h"
37 #include "tree-ssa-propagate.h"
38 #include "tree-chrec.h"
40 /* Set of SSA names found during the dominator traversal of a
41 sub-graph in find_assert_locations. */
42 static sbitmap found_in_subgraph
;
44 /* Local functions. */
45 static int compare_values (tree val1
, tree val2
);
47 /* Location information for ASSERT_EXPRs. Each instance of this
48 structure describes an ASSERT_EXPR for an SSA name. Since a single
49 SSA name may have more than one assertion associated with it, these
50 locations are kept in a linked list attached to the corresponding
54 /* Basic block where the assertion would be inserted. */
57 /* Some assertions need to be inserted on an edge (e.g., assertions
58 generated by COND_EXPRs). In those cases, BB will be NULL. */
61 /* Pointer to the statement that generated this assertion. */
62 block_stmt_iterator si
;
64 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
65 enum tree_code comp_code
;
67 /* Value being compared against. */
70 /* Next node in the linked list. */
71 struct assert_locus_d
*next
;
74 typedef struct assert_locus_d
*assert_locus_t
;
76 /* If bit I is present, it means that SSA name N_i has a list of
77 assertions that should be inserted in the IL. */
78 static bitmap need_assert_for
;
80 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
81 holds a list of ASSERT_LOCUS_T nodes that describe where
82 ASSERT_EXPRs for SSA name N_I should be inserted. */
83 static assert_locus_t
*asserts_for
;
85 /* Set of blocks visited in find_assert_locations. Used to avoid
86 visiting the same block more than once. */
87 static sbitmap blocks_visited
;
89 /* Value range array. After propagation, VR_VALUE[I] holds the range
90 of values that SSA name N_I may take. */
91 static value_range_t
**vr_value
;
94 /* Return true if ARG is marked with the nonnull attribute in the
95 current function signature. */
98 nonnull_arg_p (tree arg
)
100 tree t
, attrs
, fntype
;
101 unsigned HOST_WIDE_INT arg_num
;
103 gcc_assert (TREE_CODE (arg
) == PARM_DECL
&& POINTER_TYPE_P (TREE_TYPE (arg
)));
105 fntype
= TREE_TYPE (current_function_decl
);
106 attrs
= lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype
));
108 /* If "nonnull" wasn't specified, we know nothing about the argument. */
109 if (attrs
== NULL_TREE
)
112 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
113 if (TREE_VALUE (attrs
) == NULL_TREE
)
116 /* Get the position number for ARG in the function signature. */
117 for (arg_num
= 1, t
= DECL_ARGUMENTS (current_function_decl
);
119 t
= TREE_CHAIN (t
), arg_num
++)
125 gcc_assert (t
== arg
);
127 /* Now see if ARG_NUM is mentioned in the nonnull list. */
128 for (t
= TREE_VALUE (attrs
); t
; t
= TREE_CHAIN (t
))
130 if (compare_tree_int (TREE_VALUE (t
), arg_num
) == 0)
138 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
141 set_value_range (value_range_t
*vr
, enum value_range_type t
, tree min
,
142 tree max
, bitmap equiv
)
144 #if defined ENABLE_CHECKING
145 /* Check the validity of the range. */
146 if (t
== VR_RANGE
|| t
== VR_ANTI_RANGE
)
150 gcc_assert (min
&& max
);
152 if (INTEGRAL_TYPE_P (TREE_TYPE (min
)) && t
== VR_ANTI_RANGE
)
153 gcc_assert (min
!= TYPE_MIN_VALUE (TREE_TYPE (min
))
154 || max
!= TYPE_MAX_VALUE (TREE_TYPE (max
)));
156 cmp
= compare_values (min
, max
);
157 gcc_assert (cmp
== 0 || cmp
== -1 || cmp
== -2);
160 if (t
== VR_UNDEFINED
|| t
== VR_VARYING
)
161 gcc_assert (min
== NULL_TREE
&& max
== NULL_TREE
);
163 if (t
== VR_UNDEFINED
|| t
== VR_VARYING
)
164 gcc_assert (equiv
== NULL
|| bitmap_empty_p (equiv
));
171 /* Since updating the equivalence set involves deep copying the
172 bitmaps, only do it if absolutely necessary. */
173 if (vr
->equiv
== NULL
)
174 vr
->equiv
= BITMAP_ALLOC (NULL
);
176 if (equiv
!= vr
->equiv
)
178 if (equiv
&& !bitmap_empty_p (equiv
))
179 bitmap_copy (vr
->equiv
, equiv
);
181 bitmap_clear (vr
->equiv
);
186 /* Copy value range FROM into value range TO. */
189 copy_value_range (value_range_t
*to
, value_range_t
*from
)
191 set_value_range (to
, from
->type
, from
->min
, from
->max
, from
->equiv
);
194 /* Set value range VR to a non-negative range of type TYPE. */
197 set_value_range_to_nonnegative (value_range_t
*vr
, tree type
)
199 tree zero
= build_int_cst (type
, 0);
200 set_value_range (vr
, VR_RANGE
, zero
, TYPE_MAX_VALUE (type
), vr
->equiv
);
203 /* Set value range VR to a non-NULL range of type TYPE. */
206 set_value_range_to_nonnull (value_range_t
*vr
, tree type
)
208 tree zero
= build_int_cst (type
, 0);
209 set_value_range (vr
, VR_ANTI_RANGE
, zero
, zero
, vr
->equiv
);
213 /* Set value range VR to a NULL range of type TYPE. */
216 set_value_range_to_null (value_range_t
*vr
, tree type
)
218 tree zero
= build_int_cst (type
, 0);
219 set_value_range (vr
, VR_RANGE
, zero
, zero
, vr
->equiv
);
223 /* Set value range VR to VR_VARYING. */
226 set_value_range_to_varying (value_range_t
*vr
)
228 vr
->type
= VR_VARYING
;
229 vr
->min
= vr
->max
= NULL_TREE
;
231 bitmap_clear (vr
->equiv
);
235 /* Set value range VR to VR_UNDEFINED. */
238 set_value_range_to_undefined (value_range_t
*vr
)
240 vr
->type
= VR_UNDEFINED
;
241 vr
->min
= vr
->max
= NULL_TREE
;
243 bitmap_clear (vr
->equiv
);
247 /* Return value range information for VAR.
249 If we have no values ranges recorded (ie, VRP is not running), then
250 return NULL. Otherwise create an empty range if none existed for VAR. */
252 static value_range_t
*
253 get_value_range (tree var
)
257 unsigned ver
= SSA_NAME_VERSION (var
);
259 /* If we have no recorded ranges, then return NULL. */
267 /* Create a default value range. */
268 vr_value
[ver
] = vr
= XNEW (value_range_t
);
269 memset (vr
, 0, sizeof (*vr
));
271 /* Allocate an equivalence set. */
272 vr
->equiv
= BITMAP_ALLOC (NULL
);
274 /* If VAR is a default definition, the variable can take any value
276 sym
= SSA_NAME_VAR (var
);
277 if (var
== default_def (sym
))
279 /* Try to use the "nonnull" attribute to create ~[0, 0]
280 anti-ranges for pointers. Note that this is only valid with
281 default definitions of PARM_DECLs. */
282 if (TREE_CODE (sym
) == PARM_DECL
283 && POINTER_TYPE_P (TREE_TYPE (sym
))
284 && nonnull_arg_p (sym
))
285 set_value_range_to_nonnull (vr
, TREE_TYPE (sym
));
287 set_value_range_to_varying (vr
);
294 /* Update the value range and equivalence set for variable VAR to
295 NEW_VR. Return true if NEW_VR is different from VAR's previous
298 NOTE: This function assumes that NEW_VR is a temporary value range
299 object created for the sole purpose of updating VAR's range. The
300 storage used by the equivalence set from NEW_VR will be freed by
301 this function. Do not call update_value_range when NEW_VR
302 is the range object associated with another SSA name. */
305 update_value_range (tree var
, value_range_t
*new_vr
)
307 value_range_t
*old_vr
;
310 /* Update the value range, if necessary. */
311 old_vr
= get_value_range (var
);
312 is_new
= old_vr
->type
!= new_vr
->type
313 || old_vr
->min
!= new_vr
->min
314 || old_vr
->max
!= new_vr
->max
315 || (old_vr
->equiv
== NULL
&& new_vr
->equiv
)
316 || (old_vr
->equiv
&& new_vr
->equiv
== NULL
)
317 || (!bitmap_equal_p (old_vr
->equiv
, new_vr
->equiv
));
320 set_value_range (old_vr
, new_vr
->type
, new_vr
->min
, new_vr
->max
,
323 BITMAP_FREE (new_vr
->equiv
);
324 new_vr
->equiv
= NULL
;
330 /* Add VAR and VAR's equivalence set to EQUIV. */
333 add_equivalence (bitmap equiv
, tree var
)
335 unsigned ver
= SSA_NAME_VERSION (var
);
336 value_range_t
*vr
= vr_value
[ver
];
338 bitmap_set_bit (equiv
, ver
);
340 bitmap_ior_into (equiv
, vr
->equiv
);
344 /* Return true if VR is ~[0, 0]. */
347 range_is_nonnull (value_range_t
*vr
)
349 return vr
->type
== VR_ANTI_RANGE
350 && integer_zerop (vr
->min
)
351 && integer_zerop (vr
->max
);
355 /* Return true if VR is [0, 0]. */
358 range_is_null (value_range_t
*vr
)
360 return vr
->type
== VR_RANGE
361 && integer_zerop (vr
->min
)
362 && integer_zerop (vr
->max
);
366 /* Return true if value range VR involves at least one symbol. */
369 symbolic_range_p (value_range_t
*vr
)
371 return (!is_gimple_min_invariant (vr
->min
)
372 || !is_gimple_min_invariant (vr
->max
));
375 /* Like tree_expr_nonnegative_p, but this function uses value ranges
379 vrp_expr_computes_nonnegative (tree expr
)
381 return tree_expr_nonnegative_p (expr
);
384 /* Like tree_expr_nonzero_p, but this function uses value ranges
388 vrp_expr_computes_nonzero (tree expr
)
390 if (tree_expr_nonzero_p (expr
))
393 /* If we have an expression of the form &X->a, then the expression
394 is nonnull if X is nonnull. */
395 if (TREE_CODE (expr
) == ADDR_EXPR
)
397 tree base
= get_base_address (TREE_OPERAND (expr
, 0));
399 if (base
!= NULL_TREE
400 && TREE_CODE (base
) == INDIRECT_REF
401 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
403 value_range_t
*vr
= get_value_range (TREE_OPERAND (base
, 0));
404 if (range_is_nonnull (vr
))
412 /* Returns true if EXPR is a valid value (as expected by compare_values) --
413 a gimple invariant, or SSA_NAME +- CST. */
416 valid_value_p (tree expr
)
418 if (TREE_CODE (expr
) == SSA_NAME
)
421 if (TREE_CODE (expr
) == PLUS_EXPR
422 || TREE_CODE (expr
) == MINUS_EXPR
)
423 return (TREE_CODE (TREE_OPERAND (expr
, 0)) == SSA_NAME
424 && TREE_CODE (TREE_OPERAND (expr
, 1)) == INTEGER_CST
);
426 return is_gimple_min_invariant (expr
);
429 /* Compare two values VAL1 and VAL2. Return
431 -2 if VAL1 and VAL2 cannot be compared at compile-time,
434 +1 if VAL1 > VAL2, and
437 This is similar to tree_int_cst_compare but supports pointer values
438 and values that cannot be compared at compile time. */
441 compare_values (tree val1
, tree val2
)
446 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
448 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1
))
449 == POINTER_TYPE_P (TREE_TYPE (val2
)));
451 if ((TREE_CODE (val1
) == SSA_NAME
452 || TREE_CODE (val1
) == PLUS_EXPR
453 || TREE_CODE (val1
) == MINUS_EXPR
)
454 && (TREE_CODE (val2
) == SSA_NAME
455 || TREE_CODE (val2
) == PLUS_EXPR
456 || TREE_CODE (val2
) == MINUS_EXPR
))
459 enum tree_code code1
, code2
;
461 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
462 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
463 same name, return -2. */
464 if (TREE_CODE (val1
) == SSA_NAME
)
472 code1
= TREE_CODE (val1
);
473 n1
= TREE_OPERAND (val1
, 0);
474 c1
= TREE_OPERAND (val1
, 1);
475 if (tree_int_cst_sgn (c1
) == -1)
477 c1
= fold_unary_to_constant (NEGATE_EXPR
, TREE_TYPE (c1
), c1
);
480 code1
= code1
== MINUS_EXPR
? PLUS_EXPR
: MINUS_EXPR
;
484 if (TREE_CODE (val2
) == SSA_NAME
)
492 code2
= TREE_CODE (val2
);
493 n2
= TREE_OPERAND (val2
, 0);
494 c2
= TREE_OPERAND (val2
, 1);
495 if (tree_int_cst_sgn (c2
) == -1)
497 c2
= fold_unary_to_constant (NEGATE_EXPR
, TREE_TYPE (c2
), c2
);
500 code2
= code2
== MINUS_EXPR
? PLUS_EXPR
: MINUS_EXPR
;
504 /* Both values must use the same name. */
508 if (code1
== SSA_NAME
509 && code2
== SSA_NAME
)
513 /* If overflow is defined we cannot simplify more. */
514 if (TYPE_UNSIGNED (TREE_TYPE (val1
))
518 if (code1
== SSA_NAME
)
520 if (code2
== PLUS_EXPR
)
521 /* NAME < NAME + CST */
523 else if (code2
== MINUS_EXPR
)
524 /* NAME > NAME - CST */
527 else if (code1
== PLUS_EXPR
)
529 if (code2
== SSA_NAME
)
530 /* NAME + CST > NAME */
532 else if (code2
== PLUS_EXPR
)
533 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
534 return compare_values (c1
, c2
);
535 else if (code2
== MINUS_EXPR
)
536 /* NAME + CST1 > NAME - CST2 */
539 else if (code1
== MINUS_EXPR
)
541 if (code2
== SSA_NAME
)
542 /* NAME - CST < NAME */
544 else if (code2
== PLUS_EXPR
)
545 /* NAME - CST1 < NAME + CST2 */
547 else if (code2
== MINUS_EXPR
)
548 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
549 C1 and C2 are swapped in the call to compare_values. */
550 return compare_values (c2
, c1
);
556 /* We cannot compare non-constants. */
557 if (!is_gimple_min_invariant (val1
) || !is_gimple_min_invariant (val2
))
560 if (!POINTER_TYPE_P (TREE_TYPE (val1
)))
562 /* We cannot compare overflowed values. */
563 if (TREE_OVERFLOW (val1
) || TREE_OVERFLOW (val2
))
566 return tree_int_cst_compare (val1
, val2
);
572 /* First see if VAL1 and VAL2 are not the same. */
573 if (val1
== val2
|| operand_equal_p (val1
, val2
, 0))
576 /* If VAL1 is a lower address than VAL2, return -1. */
577 t
= fold_binary (LT_EXPR
, boolean_type_node
, val1
, val2
);
578 if (t
== boolean_true_node
)
581 /* If VAL1 is a higher address than VAL2, return +1. */
582 t
= fold_binary (GT_EXPR
, boolean_type_node
, val1
, val2
);
583 if (t
== boolean_true_node
)
586 /* If VAL1 is different than VAL2, return +2. */
587 t
= fold_binary (NE_EXPR
, boolean_type_node
, val1
, val2
);
588 if (t
== boolean_true_node
)
596 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
597 0 if VAL is not inside VR,
598 -2 if we cannot tell either way.
600 FIXME, the current semantics of this functions are a bit quirky
601 when taken in the context of VRP. In here we do not care
602 about VR's type. If VR is the anti-range ~[3, 5] the call
603 value_inside_range (4, VR) will return 1.
605 This is counter-intuitive in a strict sense, but the callers
606 currently expect this. They are calling the function
607 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
608 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
611 This also applies to value_ranges_intersect_p and
612 range_includes_zero_p. The semantics of VR_RANGE and
613 VR_ANTI_RANGE should be encoded here, but that also means
614 adapting the users of these functions to the new semantics. */
617 value_inside_range (tree val
, value_range_t
*vr
)
621 cmp1
= fold_binary_to_constant (GE_EXPR
, boolean_type_node
, val
, vr
->min
);
625 cmp2
= fold_binary_to_constant (LE_EXPR
, boolean_type_node
, val
, vr
->max
);
629 return cmp1
== boolean_true_node
&& cmp2
== boolean_true_node
;
633 /* Return true if value ranges VR0 and VR1 have a non-empty
637 value_ranges_intersect_p (value_range_t
*vr0
, value_range_t
*vr1
)
639 return (value_inside_range (vr1
->min
, vr0
) == 1
640 || value_inside_range (vr1
->max
, vr0
) == 1
641 || value_inside_range (vr0
->min
, vr1
) == 1
642 || value_inside_range (vr0
->max
, vr1
) == 1);
646 /* Return true if VR includes the value zero, false otherwise. FIXME,
647 currently this will return false for an anti-range like ~[-4, 3].
648 This will be wrong when the semantics of value_inside_range are
649 modified (currently the users of this function expect these
653 range_includes_zero_p (value_range_t
*vr
)
657 gcc_assert (vr
->type
!= VR_UNDEFINED
658 && vr
->type
!= VR_VARYING
659 && !symbolic_range_p (vr
));
661 zero
= build_int_cst (TREE_TYPE (vr
->min
), 0);
662 return (value_inside_range (zero
, vr
) == 1);
665 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
666 false otherwise or if no value range information is available. */
669 ssa_name_nonnegative_p (tree t
)
671 value_range_t
*vr
= get_value_range (t
);
676 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
677 which would return a useful value should be encoded as a VR_RANGE. */
678 if (vr
->type
== VR_RANGE
)
680 int result
= compare_values (vr
->min
, integer_zero_node
);
682 return (result
== 0 || result
== 1);
687 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
688 false otherwise or if no value range information is available. */
691 ssa_name_nonzero_p (tree t
)
693 value_range_t
*vr
= get_value_range (t
);
698 /* A VR_RANGE which does not include zero is a nonzero value. */
699 if (vr
->type
== VR_RANGE
&& !symbolic_range_p (vr
))
700 return ! range_includes_zero_p (vr
);
702 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
703 if (vr
->type
== VR_ANTI_RANGE
&& !symbolic_range_p (vr
))
704 return range_includes_zero_p (vr
);
710 /* When extracting ranges from X_i = ASSERT_EXPR <Y_j, pred>, we will
711 initially consider X_i and Y_j equivalent, so the equivalence set
712 of Y_j is added to the equivalence set of X_i. However, it is
713 possible to have a chain of ASSERT_EXPRs whose predicates are
714 actually incompatible. This is usually the result of nesting of
715 contradictory if-then-else statements. For instance, in PR 24670:
717 count_4 has range [-INF, 63]
721 count_19 = ASSERT_EXPR <count_4, count_4 != 0>
724 count_18 = ASSERT_EXPR <count_19, count_19 > 63>
730 Notice that 'if (count_19 > 63)' is trivially false and will be
731 folded out at the end. However, during propagation, the flowgraph
732 is not cleaned up and so, VRP will evaluate predicates more
733 predicates than necessary, so it must support these
734 inconsistencies. The problem here is that because of the chaining
735 of ASSERT_EXPRs, the equivalency set for count_18 includes count_4.
736 Since count_4 has an incompatible range, we ICE when evaluating the
737 ranges in the equivalency set. So, we need to remove count_4 from
741 fix_equivalence_set (value_range_t
*vr_p
)
745 bitmap e
= vr_p
->equiv
;
746 bitmap to_remove
= BITMAP_ALLOC (NULL
);
748 /* Only detect inconsistencies on numeric ranges. */
749 if (vr_p
->type
== VR_VARYING
750 || vr_p
->type
== VR_UNDEFINED
751 || symbolic_range_p (vr_p
))
754 EXECUTE_IF_SET_IN_BITMAP (e
, 0, i
, bi
)
756 value_range_t
*equiv_vr
= vr_value
[i
];
758 if (equiv_vr
->type
== VR_VARYING
759 || equiv_vr
->type
== VR_UNDEFINED
760 || symbolic_range_p (equiv_vr
))
763 if (equiv_vr
->type
== VR_RANGE
764 && vr_p
->type
== VR_RANGE
765 && !value_ranges_intersect_p (vr_p
, equiv_vr
))
766 bitmap_set_bit (to_remove
, i
);
767 else if ((equiv_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_ANTI_RANGE
)
768 || (equiv_vr
->type
== VR_ANTI_RANGE
&& vr_p
->type
== VR_RANGE
))
770 /* A range and an anti-range have an empty intersection if
771 their end points are the same. FIXME,
772 value_ranges_intersect_p should handle this
774 if (compare_values (equiv_vr
->min
, vr_p
->min
) == 0
775 && compare_values (equiv_vr
->max
, vr_p
->max
) == 0)
776 bitmap_set_bit (to_remove
, i
);
780 bitmap_and_compl_into (vr_p
->equiv
, to_remove
);
781 BITMAP_FREE (to_remove
);
785 /* Extract value range information from an ASSERT_EXPR EXPR and store
789 extract_range_from_assert (value_range_t
*vr_p
, tree expr
)
791 tree var
, cond
, limit
, min
, max
, type
;
792 value_range_t
*var_vr
, *limit_vr
;
793 enum tree_code cond_code
;
795 var
= ASSERT_EXPR_VAR (expr
);
796 cond
= ASSERT_EXPR_COND (expr
);
798 gcc_assert (COMPARISON_CLASS_P (cond
));
800 /* Find VAR in the ASSERT_EXPR conditional. */
801 if (var
== TREE_OPERAND (cond
, 0))
803 /* If the predicate is of the form VAR COMP LIMIT, then we just
804 take LIMIT from the RHS and use the same comparison code. */
805 limit
= TREE_OPERAND (cond
, 1);
806 cond_code
= TREE_CODE (cond
);
810 /* If the predicate is of the form LIMIT COMP VAR, then we need
811 to flip around the comparison code to create the proper range
813 limit
= TREE_OPERAND (cond
, 0);
814 cond_code
= swap_tree_comparison (TREE_CODE (cond
));
817 type
= TREE_TYPE (limit
);
818 gcc_assert (limit
!= var
);
820 /* For pointer arithmetic, we only keep track of pointer equality
822 if (POINTER_TYPE_P (type
) && cond_code
!= NE_EXPR
&& cond_code
!= EQ_EXPR
)
824 set_value_range_to_varying (vr_p
);
828 /* If LIMIT is another SSA name and LIMIT has a range of its own,
829 try to use LIMIT's range to avoid creating symbolic ranges
831 limit_vr
= (TREE_CODE (limit
) == SSA_NAME
) ? get_value_range (limit
) : NULL
;
833 /* LIMIT's range is only interesting if it has any useful information. */
835 && (limit_vr
->type
== VR_UNDEFINED
836 || limit_vr
->type
== VR_VARYING
837 || symbolic_range_p (limit_vr
)))
840 /* Initially, the new range has the same set of equivalences of
841 VAR's range. This will be revised before returning the final
842 value. Since assertions may be chained via mutually exclusive
843 predicates, we will need to trim the set of equivalences before
845 gcc_assert (vr_p
->equiv
== NULL
);
846 vr_p
->equiv
= BITMAP_ALLOC (NULL
);
847 add_equivalence (vr_p
->equiv
, var
);
849 /* Extract a new range based on the asserted comparison for VAR and
850 LIMIT's value range. Notice that if LIMIT has an anti-range, we
851 will only use it for equality comparisons (EQ_EXPR). For any
852 other kind of assertion, we cannot derive a range from LIMIT's
853 anti-range that can be used to describe the new range. For
854 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
855 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
856 no single range for x_2 that could describe LE_EXPR, so we might
857 as well build the range [b_4, +INF] for it. */
858 if (cond_code
== EQ_EXPR
)
860 enum value_range_type range_type
;
864 range_type
= limit_vr
->type
;
870 range_type
= VR_RANGE
;
875 set_value_range (vr_p
, range_type
, min
, max
, vr_p
->equiv
);
877 /* When asserting the equality VAR == LIMIT and LIMIT is another
878 SSA name, the new range will also inherit the equivalence set
880 if (TREE_CODE (limit
) == SSA_NAME
)
881 add_equivalence (vr_p
->equiv
, limit
);
883 else if (cond_code
== NE_EXPR
)
885 /* As described above, when LIMIT's range is an anti-range and
886 this assertion is an inequality (NE_EXPR), then we cannot
887 derive anything from the anti-range. For instance, if
888 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
889 not imply that VAR's range is [0, 0]. So, in the case of
890 anti-ranges, we just assert the inequality using LIMIT and
893 If LIMIT_VR is a range, we can only use it to build a new
894 anti-range if LIMIT_VR is a single-valued range. For
895 instance, if LIMIT_VR is [0, 1], the predicate
896 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
897 Rather, it means that for value 0 VAR should be ~[0, 0]
898 and for value 1, VAR should be ~[1, 1]. We cannot
899 represent these ranges.
901 The only situation in which we can build a valid
902 anti-range is when LIMIT_VR is a single-valued range
903 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
904 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
906 && limit_vr
->type
== VR_RANGE
907 && compare_values (limit_vr
->min
, limit_vr
->max
) == 0)
914 /* In any other case, we cannot use LIMIT's range to build a
919 /* If MIN and MAX cover the whole range for their type, then
920 just use the original LIMIT. */
921 if (INTEGRAL_TYPE_P (type
)
922 && min
== TYPE_MIN_VALUE (type
)
923 && max
== TYPE_MAX_VALUE (type
))
926 set_value_range (vr_p
, VR_ANTI_RANGE
, min
, max
, vr_p
->equiv
);
928 else if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
930 min
= TYPE_MIN_VALUE (type
);
932 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
936 /* If LIMIT_VR is of the form [N1, N2], we need to build the
937 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
942 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
943 if (cond_code
== LT_EXPR
)
945 tree one
= build_int_cst (type
, 1);
946 max
= fold_build2 (MINUS_EXPR
, type
, max
, one
);
949 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
951 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
953 max
= TYPE_MAX_VALUE (type
);
955 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
959 /* If LIMIT_VR is of the form [N1, N2], we need to build the
960 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
965 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
966 if (cond_code
== GT_EXPR
)
968 tree one
= build_int_cst (type
, 1);
969 min
= fold_build2 (PLUS_EXPR
, type
, min
, one
);
972 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
977 /* If VAR already had a known range, it may happen that the new
978 range we have computed and VAR's range are not compatible. For
982 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
984 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
986 While the above comes from a faulty program, it will cause an ICE
987 later because p_8 and p_6 will have incompatible ranges and at
988 the same time will be considered equivalent. A similar situation
992 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
994 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
996 Again i_6 and i_7 will have incompatible ranges. It would be
997 pointless to try and do anything with i_7's range because
998 anything dominated by 'if (i_5 < 5)' will be optimized away.
999 Note, due to the wa in which simulation proceeds, the statement
1000 i_7 = ASSERT_EXPR <...> we would never be visited because the
1001 conditional 'if (i_5 < 5)' always evaluates to false. However,
1002 this extra check does not hurt and may protect against future
1003 changes to VRP that may get into a situation similar to the
1004 NULL pointer dereference example.
1006 Note that these compatibility tests are only needed when dealing
1007 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1008 are both anti-ranges, they will always be compatible, because two
1009 anti-ranges will always have a non-empty intersection. */
1011 var_vr
= get_value_range (var
);
1013 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1014 ranges or anti-ranges. */
1015 if (vr_p
->type
== VR_VARYING
1016 || vr_p
->type
== VR_UNDEFINED
1017 || var_vr
->type
== VR_VARYING
1018 || var_vr
->type
== VR_UNDEFINED
1019 || symbolic_range_p (vr_p
)
1020 || symbolic_range_p (var_vr
))
1023 if (var_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_RANGE
)
1025 /* If the two ranges have a non-empty intersection, we can
1026 refine the resulting range. Since the assert expression
1027 creates an equivalency and at the same time it asserts a
1028 predicate, we can take the intersection of the two ranges to
1029 get better precision. */
1030 if (value_ranges_intersect_p (var_vr
, vr_p
))
1032 /* Use the larger of the two minimums. */
1033 if (compare_values (vr_p
->min
, var_vr
->min
) == -1)
1038 /* Use the smaller of the two maximums. */
1039 if (compare_values (vr_p
->max
, var_vr
->max
) == 1)
1044 set_value_range (vr_p
, vr_p
->type
, min
, max
, vr_p
->equiv
);
1048 /* The two ranges do not intersect, set the new range to
1049 VARYING, because we will not be able to do anything
1050 meaningful with it. */
1051 set_value_range_to_varying (vr_p
);
1054 else if ((var_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_ANTI_RANGE
)
1055 || (var_vr
->type
== VR_ANTI_RANGE
&& vr_p
->type
== VR_RANGE
))
1057 /* A range and an anti-range will cancel each other only if
1058 their ends are the same. For instance, in the example above,
1059 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1060 so VR_P should be set to VR_VARYING. */
1061 if (compare_values (var_vr
->min
, vr_p
->min
) == 0
1062 && compare_values (var_vr
->max
, vr_p
->max
) == 0)
1063 set_value_range_to_varying (vr_p
);
1066 tree min
, max
, anti_min
, anti_max
, real_min
, real_max
;
1068 /* We want to compute the logical AND of the two ranges;
1069 there are three cases to consider.
1072 1. The VR_ANTI_RANGE range is completely within the
1073 VR_RANGE and the endpoints of the ranges are
1074 different. In that case the resulting range
1075 should be whichever range is more precise.
1076 Typically that will be the VR_RANGE.
1078 2. The VR_ANTI_RANGE is completely disjoint from
1079 the VR_RANGE. In this case the resulting range
1080 should be the VR_RANGE.
1082 3. There is some overlap between the VR_ANTI_RANGE
1085 3a. If the high limit of the VR_ANTI_RANGE resides
1086 within the VR_RANGE, then the result is a new
1087 VR_RANGE starting at the high limit of the
1088 the VR_ANTI_RANGE + 1 and extending to the
1089 high limit of the original VR_RANGE.
1091 3b. If the low limit of the VR_ANTI_RANGE resides
1092 within the VR_RANGE, then the result is a new
1093 VR_RANGE starting at the low limit of the original
1094 VR_RANGE and extending to the low limit of the
1095 VR_ANTI_RANGE - 1. */
1096 if (vr_p
->type
== VR_ANTI_RANGE
)
1098 anti_min
= vr_p
->min
;
1099 anti_max
= vr_p
->max
;
1100 real_min
= var_vr
->min
;
1101 real_max
= var_vr
->max
;
1105 anti_min
= var_vr
->min
;
1106 anti_max
= var_vr
->max
;
1107 real_min
= vr_p
->min
;
1108 real_max
= vr_p
->max
;
1112 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1113 not including any endpoints. */
1114 if (compare_values (anti_max
, real_max
) == -1
1115 && compare_values (anti_min
, real_min
) == 1)
1117 set_value_range (vr_p
, VR_RANGE
, real_min
,
1118 real_max
, vr_p
->equiv
);
1120 /* Case 2, VR_ANTI_RANGE completely disjoint from
1122 else if (compare_values (anti_min
, real_max
) == 1
1123 || compare_values (anti_max
, real_min
) == -1)
1125 set_value_range (vr_p
, VR_RANGE
, real_min
,
1126 real_max
, vr_p
->equiv
);
1128 /* Case 3a, the anti-range extends into the low
1129 part of the real range. Thus creating a new
1130 low for the real range. */
1131 else if ((compare_values (anti_max
, real_min
) == 1
1132 || compare_values (anti_max
, real_min
) == 0)
1133 && compare_values (anti_max
, real_max
) == -1)
1135 min
= fold_build2 (PLUS_EXPR
, TREE_TYPE (var_vr
->min
),
1137 build_int_cst (TREE_TYPE (var_vr
->min
), 1));
1139 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1141 /* Case 3b, the anti-range extends into the high
1142 part of the real range. Thus creating a new
1143 higher for the real range. */
1144 else if (compare_values (anti_min
, real_min
) == 1
1145 && (compare_values (anti_min
, real_max
) == -1
1146 || compare_values (anti_min
, real_max
) == 0))
1148 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (var_vr
->min
),
1150 build_int_cst (TREE_TYPE (var_vr
->min
), 1));
1152 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1157 /* Remove names from the equivalence set that have ranges
1158 incompatible with VR_P. */
1160 fix_equivalence_set (vr_p
);
1164 /* Extract range information from SSA name VAR and store it in VR. If
1165 VAR has an interesting range, use it. Otherwise, create the
1166 range [VAR, VAR] and return it. This is useful in situations where
1167 we may have conditionals testing values of VARYING names. For
1174 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1178 extract_range_from_ssa_name (value_range_t
*vr
, tree var
)
1180 value_range_t
*var_vr
= get_value_range (var
);
1182 if (var_vr
->type
!= VR_UNDEFINED
&& var_vr
->type
!= VR_VARYING
)
1183 copy_value_range (vr
, var_vr
);
1185 set_value_range (vr
, VR_RANGE
, var
, var
, NULL
);
1187 add_equivalence (vr
->equiv
, var
);
1191 /* Wrapper around int_const_binop. If the operation overflows and we
1192 are not using wrapping arithmetic, then adjust the result to be
1193 -INF or +INF depending on CODE, VAL1 and VAL2. */
1196 vrp_int_const_binop (enum tree_code code
, tree val1
, tree val2
)
1201 return int_const_binop (code
, val1
, val2
, 0);
1203 /* If we are not using wrapping arithmetic, operate symbolically
1204 on -INF and +INF. */
1205 res
= int_const_binop (code
, val1
, val2
, 0);
1207 if (TYPE_UNSIGNED (TREE_TYPE (val1
)))
1209 int checkz
= compare_values (res
, val1
);
1210 bool overflow
= false;
1212 /* Ensure that res = val1 [+*] val2 >= val1
1213 or that res = val1 - val2 <= val1. */
1214 if ((code
== PLUS_EXPR
1215 && !(checkz
== 1 || checkz
== 0))
1216 || (code
== MINUS_EXPR
1217 && !(checkz
== 0 || checkz
== -1)))
1221 /* Checking for multiplication overflow is done by dividing the
1222 output of the multiplication by the first input of the
1223 multiplication. If the result of that division operation is
1224 not equal to the second input of the multiplication, then the
1225 multiplication overflowed. */
1226 else if (code
== MULT_EXPR
&& !integer_zerop (val1
))
1228 tree tmp
= int_const_binop (TRUNC_DIV_EXPR
,
1229 TYPE_MAX_VALUE (TREE_TYPE (val1
)),
1231 int check
= compare_values (tmp
, val2
);
1239 res
= copy_node (res
);
1240 TREE_OVERFLOW (res
) = 1;
1244 else if (TREE_OVERFLOW (res
)
1245 && !TREE_OVERFLOW (val1
)
1246 && !TREE_OVERFLOW (val2
))
1248 /* If the operation overflowed but neither VAL1 nor VAL2 are
1249 overflown, return -INF or +INF depending on the operation
1250 and the combination of signs of the operands. */
1251 int sgn1
= tree_int_cst_sgn (val1
);
1252 int sgn2
= tree_int_cst_sgn (val2
);
1254 /* Notice that we only need to handle the restricted set of
1255 operations handled by extract_range_from_binary_expr.
1256 Among them, only multiplication, addition and subtraction
1257 can yield overflow without overflown operands because we
1258 are working with integral types only... except in the
1259 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1260 for division too. */
1262 /* For multiplication, the sign of the overflow is given
1263 by the comparison of the signs of the operands. */
1264 if ((code
== MULT_EXPR
&& sgn1
== sgn2
)
1265 /* For addition, the operands must be of the same sign
1266 to yield an overflow. Its sign is therefore that
1267 of one of the operands, for example the first. */
1268 || (code
== PLUS_EXPR
&& sgn1
> 0)
1269 /* For subtraction, the operands must be of different
1270 signs to yield an overflow. Its sign is therefore
1271 that of the first operand or the opposite of that
1272 of the second operand. A first operand of 0 counts
1273 as positive here, for the corner case 0 - (-INF),
1274 which overflows, but must yield +INF. */
1275 || (code
== MINUS_EXPR
&& sgn1
>= 0)
1276 /* For division, the only case is -INF / -1 = +INF. */
1277 || code
== TRUNC_DIV_EXPR
1278 || code
== FLOOR_DIV_EXPR
1279 || code
== CEIL_DIV_EXPR
1280 || code
== EXACT_DIV_EXPR
1281 || code
== ROUND_DIV_EXPR
)
1282 return TYPE_MAX_VALUE (TREE_TYPE (res
));
1284 return TYPE_MIN_VALUE (TREE_TYPE (res
));
1291 /* Extract range information from a binary expression EXPR based on
1292 the ranges of each of its operands and the expression code. */
1295 extract_range_from_binary_expr (value_range_t
*vr
, tree expr
)
1297 enum tree_code code
= TREE_CODE (expr
);
1298 enum value_range_type type
;
1299 tree op0
, op1
, min
, max
;
1301 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1302 value_range_t vr1
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1304 /* Not all binary expressions can be applied to ranges in a
1305 meaningful way. Handle only arithmetic operations. */
1306 if (code
!= PLUS_EXPR
1307 && code
!= MINUS_EXPR
1308 && code
!= MULT_EXPR
1309 && code
!= TRUNC_DIV_EXPR
1310 && code
!= FLOOR_DIV_EXPR
1311 && code
!= CEIL_DIV_EXPR
1312 && code
!= EXACT_DIV_EXPR
1313 && code
!= ROUND_DIV_EXPR
1316 && code
!= BIT_AND_EXPR
1317 && code
!= TRUTH_ANDIF_EXPR
1318 && code
!= TRUTH_ORIF_EXPR
1319 && code
!= TRUTH_AND_EXPR
1320 && code
!= TRUTH_OR_EXPR
)
1322 set_value_range_to_varying (vr
);
1326 /* Get value ranges for each operand. For constant operands, create
1327 a new value range with the operand to simplify processing. */
1328 op0
= TREE_OPERAND (expr
, 0);
1329 if (TREE_CODE (op0
) == SSA_NAME
)
1330 vr0
= *(get_value_range (op0
));
1331 else if (is_gimple_min_invariant (op0
))
1332 set_value_range (&vr0
, VR_RANGE
, op0
, op0
, NULL
);
1334 set_value_range_to_varying (&vr0
);
1336 op1
= TREE_OPERAND (expr
, 1);
1337 if (TREE_CODE (op1
) == SSA_NAME
)
1338 vr1
= *(get_value_range (op1
));
1339 else if (is_gimple_min_invariant (op1
))
1340 set_value_range (&vr1
, VR_RANGE
, op1
, op1
, NULL
);
1342 set_value_range_to_varying (&vr1
);
1344 /* If either range is UNDEFINED, so is the result. */
1345 if (vr0
.type
== VR_UNDEFINED
|| vr1
.type
== VR_UNDEFINED
)
1347 set_value_range_to_undefined (vr
);
1351 /* The type of the resulting value range defaults to VR0.TYPE. */
1354 /* Refuse to operate on VARYING ranges, ranges of different kinds
1355 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1356 because we may be able to derive a useful range even if one of
1357 the operands is VR_VARYING or symbolic range. TODO, we may be
1358 able to derive anti-ranges in some cases. */
1359 if (code
!= BIT_AND_EXPR
1360 && code
!= TRUTH_AND_EXPR
1361 && code
!= TRUTH_OR_EXPR
1362 && (vr0
.type
== VR_VARYING
1363 || vr1
.type
== VR_VARYING
1364 || vr0
.type
!= vr1
.type
1365 || symbolic_range_p (&vr0
)
1366 || symbolic_range_p (&vr1
)))
1368 set_value_range_to_varying (vr
);
1372 /* Now evaluate the expression to determine the new range. */
1373 if (POINTER_TYPE_P (TREE_TYPE (expr
))
1374 || POINTER_TYPE_P (TREE_TYPE (op0
))
1375 || POINTER_TYPE_P (TREE_TYPE (op1
)))
1377 /* For pointer types, we are really only interested in asserting
1378 whether the expression evaluates to non-NULL. FIXME, we used
1379 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1380 ivopts is generating expressions with pointer multiplication
1382 if (code
== PLUS_EXPR
)
1384 if (range_is_nonnull (&vr0
) || range_is_nonnull (&vr1
))
1385 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1386 else if (range_is_null (&vr0
) && range_is_null (&vr1
))
1387 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1389 set_value_range_to_varying (vr
);
1393 /* Subtracting from a pointer, may yield 0, so just drop the
1394 resulting range to varying. */
1395 set_value_range_to_varying (vr
);
1401 /* For integer ranges, apply the operation to each end of the
1402 range and see what we end up with. */
1403 if (code
== TRUTH_ANDIF_EXPR
1404 || code
== TRUTH_ORIF_EXPR
1405 || code
== TRUTH_AND_EXPR
1406 || code
== TRUTH_OR_EXPR
)
1408 /* If one of the operands is zero, we know that the whole
1409 expression evaluates zero. */
1410 if (code
== TRUTH_AND_EXPR
1411 && ((vr0
.type
== VR_RANGE
1412 && integer_zerop (vr0
.min
)
1413 && integer_zerop (vr0
.max
))
1414 || (vr1
.type
== VR_RANGE
1415 && integer_zerop (vr1
.min
)
1416 && integer_zerop (vr1
.max
))))
1419 min
= max
= build_int_cst (TREE_TYPE (expr
), 0);
1421 /* If one of the operands is one, we know that the whole
1422 expression evaluates one. */
1423 else if (code
== TRUTH_OR_EXPR
1424 && ((vr0
.type
== VR_RANGE
1425 && integer_onep (vr0
.min
)
1426 && integer_onep (vr0
.max
))
1427 || (vr1
.type
== VR_RANGE
1428 && integer_onep (vr1
.min
)
1429 && integer_onep (vr1
.max
))))
1432 min
= max
= build_int_cst (TREE_TYPE (expr
), 1);
1434 else if (vr0
.type
!= VR_VARYING
1435 && vr1
.type
!= VR_VARYING
1436 && vr0
.type
== vr1
.type
1437 && !symbolic_range_p (&vr0
)
1438 && !symbolic_range_p (&vr1
))
1440 /* Boolean expressions cannot be folded with int_const_binop. */
1441 min
= fold_binary (code
, TREE_TYPE (expr
), vr0
.min
, vr1
.min
);
1442 max
= fold_binary (code
, TREE_TYPE (expr
), vr0
.max
, vr1
.max
);
1446 set_value_range_to_varying (vr
);
1450 else if (code
== PLUS_EXPR
1452 || code
== MAX_EXPR
)
1454 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1455 VR_VARYING. It would take more effort to compute a precise
1456 range for such a case. For example, if we have op0 == 1 and
1457 op1 == -1 with their ranges both being ~[0,0], we would have
1458 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1459 Note that we are guaranteed to have vr0.type == vr1.type at
1461 if (code
== PLUS_EXPR
&& vr0
.type
== VR_ANTI_RANGE
)
1463 set_value_range_to_varying (vr
);
1467 /* For operations that make the resulting range directly
1468 proportional to the original ranges, apply the operation to
1469 the same end of each range. */
1470 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1471 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.max
);
1473 else if (code
== MULT_EXPR
1474 || code
== TRUNC_DIV_EXPR
1475 || code
== FLOOR_DIV_EXPR
1476 || code
== CEIL_DIV_EXPR
1477 || code
== EXACT_DIV_EXPR
1478 || code
== ROUND_DIV_EXPR
)
1483 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1484 drop to VR_VARYING. It would take more effort to compute a
1485 precise range for such a case. For example, if we have
1486 op0 == 65536 and op1 == 65536 with their ranges both being
1487 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1488 we cannot claim that the product is in ~[0,0]. Note that we
1489 are guaranteed to have vr0.type == vr1.type at this
1491 if (code
== MULT_EXPR
1492 && vr0
.type
== VR_ANTI_RANGE
1493 && (flag_wrapv
|| TYPE_UNSIGNED (TREE_TYPE (op0
))))
1495 set_value_range_to_varying (vr
);
1499 /* Multiplications and divisions are a bit tricky to handle,
1500 depending on the mix of signs we have in the two ranges, we
1501 need to operate on different values to get the minimum and
1502 maximum values for the new range. One approach is to figure
1503 out all the variations of range combinations and do the
1506 However, this involves several calls to compare_values and it
1507 is pretty convoluted. It's simpler to do the 4 operations
1508 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1509 MAX1) and then figure the smallest and largest values to form
1512 /* Divisions by zero result in a VARYING value. */
1513 if (code
!= MULT_EXPR
1514 && (vr0
.type
== VR_ANTI_RANGE
|| range_includes_zero_p (&vr1
)))
1516 set_value_range_to_varying (vr
);
1520 /* Compute the 4 cross operations. */
1521 val
[0] = vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1523 val
[1] = (vr1
.max
!= vr1
.min
)
1524 ? vrp_int_const_binop (code
, vr0
.min
, vr1
.max
)
1527 val
[2] = (vr0
.max
!= vr0
.min
)
1528 ? vrp_int_const_binop (code
, vr0
.max
, vr1
.min
)
1531 val
[3] = (vr0
.min
!= vr0
.max
&& vr1
.min
!= vr1
.max
)
1532 ? vrp_int_const_binop (code
, vr0
.max
, vr1
.max
)
1535 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1539 for (i
= 1; i
< 4; i
++)
1541 if (!is_gimple_min_invariant (min
) || TREE_OVERFLOW (min
)
1542 || !is_gimple_min_invariant (max
) || TREE_OVERFLOW (max
))
1547 if (!is_gimple_min_invariant (val
[i
]) || TREE_OVERFLOW (val
[i
]))
1549 /* If we found an overflowed value, set MIN and MAX
1550 to it so that we set the resulting range to
1556 if (compare_values (val
[i
], min
) == -1)
1559 if (compare_values (val
[i
], max
) == 1)
1564 else if (code
== MINUS_EXPR
)
1566 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1567 VR_VARYING. It would take more effort to compute a precise
1568 range for such a case. For example, if we have op0 == 1 and
1569 op1 == 1 with their ranges both being ~[0,0], we would have
1570 op0 - op1 == 0, so we cannot claim that the difference is in
1571 ~[0,0]. Note that we are guaranteed to have
1572 vr0.type == vr1.type at this point. */
1573 if (vr0
.type
== VR_ANTI_RANGE
)
1575 set_value_range_to_varying (vr
);
1579 /* For MINUS_EXPR, apply the operation to the opposite ends of
1581 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.max
);
1582 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.min
);
1584 else if (code
== BIT_AND_EXPR
)
1586 if (vr0
.type
== VR_RANGE
1587 && vr0
.min
== vr0
.max
1588 && tree_expr_nonnegative_p (vr0
.max
)
1589 && TREE_CODE (vr0
.max
) == INTEGER_CST
)
1591 min
= build_int_cst (TREE_TYPE (expr
), 0);
1594 else if (vr1
.type
== VR_RANGE
1595 && vr1
.min
== vr1
.max
1596 && tree_expr_nonnegative_p (vr1
.max
)
1597 && TREE_CODE (vr1
.max
) == INTEGER_CST
)
1600 min
= build_int_cst (TREE_TYPE (expr
), 0);
1605 set_value_range_to_varying (vr
);
1612 /* If either MIN or MAX overflowed, then set the resulting range to
1614 if (!is_gimple_min_invariant (min
) || TREE_OVERFLOW (min
)
1615 || !is_gimple_min_invariant (max
) || TREE_OVERFLOW (max
))
1617 set_value_range_to_varying (vr
);
1621 cmp
= compare_values (min
, max
);
1622 if (cmp
== -2 || cmp
== 1)
1624 /* If the new range has its limits swapped around (MIN > MAX),
1625 then the operation caused one of them to wrap around, mark
1626 the new range VARYING. */
1627 set_value_range_to_varying (vr
);
1630 set_value_range (vr
, type
, min
, max
, NULL
);
1634 /* Extract range information from a unary expression EXPR based on
1635 the range of its operand and the expression code. */
1638 extract_range_from_unary_expr (value_range_t
*vr
, tree expr
)
1640 enum tree_code code
= TREE_CODE (expr
);
1643 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1645 /* Refuse to operate on certain unary expressions for which we
1646 cannot easily determine a resulting range. */
1647 if (code
== FIX_TRUNC_EXPR
1648 || code
== FIX_CEIL_EXPR
1649 || code
== FIX_FLOOR_EXPR
1650 || code
== FIX_ROUND_EXPR
1651 || code
== FLOAT_EXPR
1652 || code
== BIT_NOT_EXPR
1653 || code
== NON_LVALUE_EXPR
1654 || code
== CONJ_EXPR
)
1656 set_value_range_to_varying (vr
);
1660 /* Get value ranges for the operand. For constant operands, create
1661 a new value range with the operand to simplify processing. */
1662 op0
= TREE_OPERAND (expr
, 0);
1663 if (TREE_CODE (op0
) == SSA_NAME
)
1664 vr0
= *(get_value_range (op0
));
1665 else if (is_gimple_min_invariant (op0
))
1666 set_value_range (&vr0
, VR_RANGE
, op0
, op0
, NULL
);
1668 set_value_range_to_varying (&vr0
);
1670 /* If VR0 is UNDEFINED, so is the result. */
1671 if (vr0
.type
== VR_UNDEFINED
)
1673 set_value_range_to_undefined (vr
);
1677 /* Refuse to operate on symbolic ranges, or if neither operand is
1678 a pointer or integral type. */
1679 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
1680 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
1681 || (vr0
.type
!= VR_VARYING
1682 && symbolic_range_p (&vr0
)))
1684 set_value_range_to_varying (vr
);
1688 /* If the expression involves pointers, we are only interested in
1689 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1690 if (POINTER_TYPE_P (TREE_TYPE (expr
)) || POINTER_TYPE_P (TREE_TYPE (op0
)))
1692 if (range_is_nonnull (&vr0
) || tree_expr_nonzero_p (expr
))
1693 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1694 else if (range_is_null (&vr0
))
1695 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1697 set_value_range_to_varying (vr
);
1702 /* Handle unary expressions on integer ranges. */
1703 if (code
== NOP_EXPR
|| code
== CONVERT_EXPR
)
1705 tree inner_type
= TREE_TYPE (op0
);
1706 tree outer_type
= TREE_TYPE (expr
);
1708 /* If VR0 represents a simple range, then try to convert
1709 the min and max values for the range to the same type
1710 as OUTER_TYPE. If the results compare equal to VR0's
1711 min and max values and the new min is still less than
1712 or equal to the new max, then we can safely use the newly
1713 computed range for EXPR. This allows us to compute
1714 accurate ranges through many casts. */
1715 if (vr0
.type
== VR_RANGE
1716 || (vr0
.type
== VR_VARYING
1717 && TYPE_PRECISION (outer_type
) > TYPE_PRECISION (inner_type
)))
1719 tree new_min
, new_max
, orig_min
, orig_max
;
1721 /* Convert the input operand min/max to OUTER_TYPE. If
1722 the input has no range information, then use the min/max
1723 for the input's type. */
1724 if (vr0
.type
== VR_RANGE
)
1731 orig_min
= TYPE_MIN_VALUE (inner_type
);
1732 orig_max
= TYPE_MAX_VALUE (inner_type
);
1735 new_min
= fold_convert (outer_type
, orig_min
);
1736 new_max
= fold_convert (outer_type
, orig_max
);
1738 /* Verify the new min/max values are gimple values and
1739 that they compare equal to the original input's
1741 if (is_gimple_val (new_min
)
1742 && is_gimple_val (new_max
)
1743 && tree_int_cst_equal (new_min
, orig_min
)
1744 && tree_int_cst_equal (new_max
, orig_max
)
1745 && compare_values (new_min
, new_max
) <= 0
1746 && compare_values (new_min
, new_max
) >= -1)
1748 set_value_range (vr
, VR_RANGE
, new_min
, new_max
, vr
->equiv
);
1753 /* When converting types of different sizes, set the result to
1754 VARYING. Things like sign extensions and precision loss may
1755 change the range. For instance, if x_3 is of type 'long long
1756 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1757 is impossible to know at compile time whether y_5 will be
1759 if (TYPE_SIZE (inner_type
) != TYPE_SIZE (outer_type
)
1760 || TYPE_PRECISION (inner_type
) != TYPE_PRECISION (outer_type
))
1762 set_value_range_to_varying (vr
);
1767 /* Conversion of a VR_VARYING value to a wider type can result
1768 in a usable range. So wait until after we've handled conversions
1769 before dropping the result to VR_VARYING if we had a source
1770 operand that is VR_VARYING. */
1771 if (vr0
.type
== VR_VARYING
)
1773 set_value_range_to_varying (vr
);
1777 /* Apply the operation to each end of the range and see what we end
1779 if (code
== NEGATE_EXPR
1780 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
1782 /* NEGATE_EXPR flips the range around. */
1783 min
= (vr0
.max
== TYPE_MAX_VALUE (TREE_TYPE (expr
)) && !flag_wrapv
)
1784 ? TYPE_MIN_VALUE (TREE_TYPE (expr
))
1785 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1787 max
= (vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
)) && !flag_wrapv
)
1788 ? TYPE_MAX_VALUE (TREE_TYPE (expr
))
1789 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1792 else if (code
== NEGATE_EXPR
1793 && TYPE_UNSIGNED (TREE_TYPE (expr
)))
1795 if (!range_includes_zero_p (&vr0
))
1797 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1798 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1802 if (range_is_null (&vr0
))
1803 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1805 set_value_range_to_varying (vr
);
1809 else if (code
== ABS_EXPR
1810 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
1812 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
1815 && ((vr0
.type
== VR_RANGE
1816 && vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
)))
1817 || (vr0
.type
== VR_ANTI_RANGE
1818 && vr0
.min
!= TYPE_MIN_VALUE (TREE_TYPE (expr
))
1819 && !range_includes_zero_p (&vr0
))))
1821 set_value_range_to_varying (vr
);
1825 /* ABS_EXPR may flip the range around, if the original range
1826 included negative values. */
1827 min
= (vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
)))
1828 ? TYPE_MAX_VALUE (TREE_TYPE (expr
))
1829 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1831 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1833 cmp
= compare_values (min
, max
);
1835 /* If a VR_ANTI_RANGEs contains zero, then we have
1836 ~[-INF, min(MIN, MAX)]. */
1837 if (vr0
.type
== VR_ANTI_RANGE
)
1839 if (range_includes_zero_p (&vr0
))
1841 tree type_min_value
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
1843 /* Take the lower of the two values. */
1847 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
1848 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
1849 flag_wrapv is set and the original anti-range doesn't include
1850 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
1851 min
= (flag_wrapv
&& vr0
.min
!= type_min_value
1852 ? int_const_binop (PLUS_EXPR
,
1854 integer_one_node
, 0)
1859 /* All else has failed, so create the range [0, INF], even for
1860 flag_wrapv since TYPE_MIN_VALUE is in the original
1862 vr0
.type
= VR_RANGE
;
1863 min
= build_int_cst (TREE_TYPE (expr
), 0);
1864 max
= TYPE_MAX_VALUE (TREE_TYPE (expr
));
1868 /* If the range contains zero then we know that the minimum value in the
1869 range will be zero. */
1870 else if (range_includes_zero_p (&vr0
))
1874 min
= build_int_cst (TREE_TYPE (expr
), 0);
1878 /* If the range was reversed, swap MIN and MAX. */
1889 /* Otherwise, operate on each end of the range. */
1890 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1891 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1894 cmp
= compare_values (min
, max
);
1895 if (cmp
== -2 || cmp
== 1)
1897 /* If the new range has its limits swapped around (MIN > MAX),
1898 then the operation caused one of them to wrap around, mark
1899 the new range VARYING. */
1900 set_value_range_to_varying (vr
);
1903 set_value_range (vr
, vr0
.type
, min
, max
, NULL
);
1907 /* Extract range information from a comparison expression EXPR based
1908 on the range of its operand and the expression code. */
1911 extract_range_from_comparison (value_range_t
*vr
, tree expr
)
1913 tree val
= vrp_evaluate_conditional (expr
, false);
1916 /* Since this expression was found on the RHS of an assignment,
1917 its type may be different from _Bool. Convert VAL to EXPR's
1919 val
= fold_convert (TREE_TYPE (expr
), val
);
1920 set_value_range (vr
, VR_RANGE
, val
, val
, vr
->equiv
);
1923 set_value_range_to_varying (vr
);
1927 /* Try to compute a useful range out of expression EXPR and store it
1931 extract_range_from_expr (value_range_t
*vr
, tree expr
)
1933 enum tree_code code
= TREE_CODE (expr
);
1935 if (code
== ASSERT_EXPR
)
1936 extract_range_from_assert (vr
, expr
);
1937 else if (code
== SSA_NAME
)
1938 extract_range_from_ssa_name (vr
, expr
);
1939 else if (TREE_CODE_CLASS (code
) == tcc_binary
1940 || code
== TRUTH_ANDIF_EXPR
1941 || code
== TRUTH_ORIF_EXPR
1942 || code
== TRUTH_AND_EXPR
1943 || code
== TRUTH_OR_EXPR
1944 || code
== TRUTH_XOR_EXPR
)
1945 extract_range_from_binary_expr (vr
, expr
);
1946 else if (TREE_CODE_CLASS (code
) == tcc_unary
)
1947 extract_range_from_unary_expr (vr
, expr
);
1948 else if (TREE_CODE_CLASS (code
) == tcc_comparison
)
1949 extract_range_from_comparison (vr
, expr
);
1950 else if (is_gimple_min_invariant (expr
))
1951 set_value_range (vr
, VR_RANGE
, expr
, expr
, NULL
);
1953 set_value_range_to_varying (vr
);
1955 /* If we got a varying range from the tests above, try a final
1956 time to derive a nonnegative or nonzero range. This time
1957 relying primarily on generic routines in fold in conjunction
1959 if (vr
->type
== VR_VARYING
)
1961 if (INTEGRAL_TYPE_P (TREE_TYPE (expr
))
1962 && vrp_expr_computes_nonnegative (expr
))
1963 set_value_range_to_nonnegative (vr
, TREE_TYPE (expr
));
1964 else if (vrp_expr_computes_nonzero (expr
))
1965 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1969 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1970 would be profitable to adjust VR using scalar evolution information
1971 for VAR. If so, update VR with the new limits. */
1974 adjust_range_with_scev (value_range_t
*vr
, struct loop
*loop
, tree stmt
,
1977 tree init
, step
, chrec
;
1978 enum ev_direction dir
;
1980 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1981 better opportunities than a regular range, but I'm not sure. */
1982 if (vr
->type
== VR_ANTI_RANGE
)
1985 chrec
= instantiate_parameters (loop
, analyze_scalar_evolution (loop
, var
));
1986 if (TREE_CODE (chrec
) != POLYNOMIAL_CHREC
)
1989 init
= initial_condition_in_loop_num (chrec
, loop
->num
);
1990 step
= evolution_part_in_loop_num (chrec
, loop
->num
);
1992 /* If STEP is symbolic, we can't know whether INIT will be the
1993 minimum or maximum value in the range. Also, unless INIT is
1994 a simple expression, compare_values and possibly other functions
1995 in tree-vrp won't be able to handle it. */
1996 if (step
== NULL_TREE
1997 || !is_gimple_min_invariant (step
)
1998 || !valid_value_p (init
))
2001 dir
= scev_direction (chrec
);
2002 if (/* Do not adjust ranges if we do not know whether the iv increases
2003 or decreases, ... */
2004 dir
== EV_DIR_UNKNOWN
2005 /* ... or if it may wrap. */
2006 || scev_probably_wraps_p (init
, step
, stmt
,
2007 current_loops
->parray
[CHREC_VARIABLE (chrec
)],
2011 if (!POINTER_TYPE_P (TREE_TYPE (init
))
2012 && (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
))
2014 /* For VARYING or UNDEFINED ranges, just about anything we get
2015 from scalar evolutions should be better. */
2016 tree min
= TYPE_MIN_VALUE (TREE_TYPE (init
));
2017 tree max
= TYPE_MAX_VALUE (TREE_TYPE (init
));
2019 if (dir
== EV_DIR_DECREASES
)
2024 /* If we would create an invalid range, then just assume we
2025 know absolutely nothing. This may be over-conservative,
2026 but it's clearly safe. */
2027 if (compare_values (min
, max
) == 1)
2030 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
2032 else if (vr
->type
== VR_RANGE
)
2037 if (dir
== EV_DIR_DECREASES
)
2039 /* INIT is the maximum value. If INIT is lower than VR->MAX
2040 but no smaller than VR->MIN, set VR->MAX to INIT. */
2041 if (compare_values (init
, max
) == -1)
2045 /* If we just created an invalid range with the minimum
2046 greater than the maximum, take the minimum all the
2048 if (compare_values (min
, max
) == 1)
2049 min
= TYPE_MIN_VALUE (TREE_TYPE (min
));
2054 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2055 if (compare_values (init
, min
) == 1)
2059 /* If we just created an invalid range with the minimum
2060 greater than the maximum, take the maximum all the
2062 if (compare_values (min
, max
) == 1)
2063 max
= TYPE_MAX_VALUE (TREE_TYPE (max
));
2067 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
2072 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2074 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2075 all the values in the ranges.
2077 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2079 - Return NULL_TREE if it is not always possible to determine the
2080 value of the comparison. */
2084 compare_ranges (enum tree_code comp
, value_range_t
*vr0
, value_range_t
*vr1
)
2086 /* VARYING or UNDEFINED ranges cannot be compared. */
2087 if (vr0
->type
== VR_VARYING
2088 || vr0
->type
== VR_UNDEFINED
2089 || vr1
->type
== VR_VARYING
2090 || vr1
->type
== VR_UNDEFINED
)
2093 /* Anti-ranges need to be handled separately. */
2094 if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
2096 /* If both are anti-ranges, then we cannot compute any
2098 if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
2101 /* These comparisons are never statically computable. */
2108 /* Equality can be computed only between a range and an
2109 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2110 if (vr0
->type
== VR_RANGE
)
2112 /* To simplify processing, make VR0 the anti-range. */
2113 value_range_t
*tmp
= vr0
;
2118 gcc_assert (comp
== NE_EXPR
|| comp
== EQ_EXPR
);
2120 if (compare_values (vr0
->min
, vr1
->min
) == 0
2121 && compare_values (vr0
->max
, vr1
->max
) == 0)
2122 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
2127 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2128 operands around and change the comparison code. */
2129 if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
2132 comp
= (comp
== GT_EXPR
) ? LT_EXPR
: LE_EXPR
;
2138 if (comp
== EQ_EXPR
)
2140 /* Equality may only be computed if both ranges represent
2141 exactly one value. */
2142 if (compare_values (vr0
->min
, vr0
->max
) == 0
2143 && compare_values (vr1
->min
, vr1
->max
) == 0)
2145 int cmp_min
= compare_values (vr0
->min
, vr1
->min
);
2146 int cmp_max
= compare_values (vr0
->max
, vr1
->max
);
2147 if (cmp_min
== 0 && cmp_max
== 0)
2148 return boolean_true_node
;
2149 else if (cmp_min
!= -2 && cmp_max
!= -2)
2150 return boolean_false_node
;
2152 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2153 else if (compare_values (vr0
->min
, vr1
->max
) == 1
2154 || compare_values (vr1
->min
, vr0
->max
) == 1)
2155 return boolean_false_node
;
2159 else if (comp
== NE_EXPR
)
2163 /* If VR0 is completely to the left or completely to the right
2164 of VR1, they are always different. Notice that we need to
2165 make sure that both comparisons yield similar results to
2166 avoid comparing values that cannot be compared at
2168 cmp1
= compare_values (vr0
->max
, vr1
->min
);
2169 cmp2
= compare_values (vr0
->min
, vr1
->max
);
2170 if ((cmp1
== -1 && cmp2
== -1) || (cmp1
== 1 && cmp2
== 1))
2171 return boolean_true_node
;
2173 /* If VR0 and VR1 represent a single value and are identical,
2175 else if (compare_values (vr0
->min
, vr0
->max
) == 0
2176 && compare_values (vr1
->min
, vr1
->max
) == 0
2177 && compare_values (vr0
->min
, vr1
->min
) == 0
2178 && compare_values (vr0
->max
, vr1
->max
) == 0)
2179 return boolean_false_node
;
2181 /* Otherwise, they may or may not be different. */
2185 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
2189 /* If VR0 is to the left of VR1, return true. */
2190 tst
= compare_values (vr0
->max
, vr1
->min
);
2191 if ((comp
== LT_EXPR
&& tst
== -1)
2192 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
2193 return boolean_true_node
;
2195 /* If VR0 is to the right of VR1, return false. */
2196 tst
= compare_values (vr0
->min
, vr1
->max
);
2197 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
2198 || (comp
== LE_EXPR
&& tst
== 1))
2199 return boolean_false_node
;
2201 /* Otherwise, we don't know. */
2209 /* Given a value range VR, a value VAL and a comparison code COMP, return
2210 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2211 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2212 always returns false. Return NULL_TREE if it is not always
2213 possible to determine the value of the comparison. */
2216 compare_range_with_value (enum tree_code comp
, value_range_t
*vr
, tree val
)
2218 if (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
)
2221 /* Anti-ranges need to be handled separately. */
2222 if (vr
->type
== VR_ANTI_RANGE
)
2224 /* For anti-ranges, the only predicates that we can compute at
2225 compile time are equality and inequality. */
2232 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2233 if (value_inside_range (val
, vr
) == 1)
2234 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
2239 if (comp
== EQ_EXPR
)
2241 /* EQ_EXPR may only be computed if VR represents exactly
2243 if (compare_values (vr
->min
, vr
->max
) == 0)
2245 int cmp
= compare_values (vr
->min
, val
);
2247 return boolean_true_node
;
2248 else if (cmp
== -1 || cmp
== 1 || cmp
== 2)
2249 return boolean_false_node
;
2251 else if (compare_values (val
, vr
->min
) == -1
2252 || compare_values (vr
->max
, val
) == -1)
2253 return boolean_false_node
;
2257 else if (comp
== NE_EXPR
)
2259 /* If VAL is not inside VR, then they are always different. */
2260 if (compare_values (vr
->max
, val
) == -1
2261 || compare_values (vr
->min
, val
) == 1)
2262 return boolean_true_node
;
2264 /* If VR represents exactly one value equal to VAL, then return
2266 if (compare_values (vr
->min
, vr
->max
) == 0
2267 && compare_values (vr
->min
, val
) == 0)
2268 return boolean_false_node
;
2270 /* Otherwise, they may or may not be different. */
2273 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
2277 /* If VR is to the left of VAL, return true. */
2278 tst
= compare_values (vr
->max
, val
);
2279 if ((comp
== LT_EXPR
&& tst
== -1)
2280 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
2281 return boolean_true_node
;
2283 /* If VR is to the right of VAL, return false. */
2284 tst
= compare_values (vr
->min
, val
);
2285 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
2286 || (comp
== LE_EXPR
&& tst
== 1))
2287 return boolean_false_node
;
2289 /* Otherwise, we don't know. */
2292 else if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
2296 /* If VR is to the right of VAL, return true. */
2297 tst
= compare_values (vr
->min
, val
);
2298 if ((comp
== GT_EXPR
&& tst
== 1)
2299 || (comp
== GE_EXPR
&& (tst
== 0 || tst
== 1)))
2300 return boolean_true_node
;
2302 /* If VR is to the left of VAL, return false. */
2303 tst
= compare_values (vr
->max
, val
);
2304 if ((comp
== GT_EXPR
&& (tst
== -1 || tst
== 0))
2305 || (comp
== GE_EXPR
&& tst
== -1))
2306 return boolean_false_node
;
2308 /* Otherwise, we don't know. */
2316 /* Debugging dumps. */
2318 void dump_value_range (FILE *, value_range_t
*);
2319 void debug_value_range (value_range_t
*);
2320 void dump_all_value_ranges (FILE *);
2321 void debug_all_value_ranges (void);
2322 void dump_vr_equiv (FILE *, bitmap
);
2323 void debug_vr_equiv (bitmap
);
2326 /* Dump value range VR to FILE. */
2329 dump_value_range (FILE *file
, value_range_t
*vr
)
2332 fprintf (file
, "[]");
2333 else if (vr
->type
== VR_UNDEFINED
)
2334 fprintf (file
, "UNDEFINED");
2335 else if (vr
->type
== VR_RANGE
|| vr
->type
== VR_ANTI_RANGE
)
2337 tree type
= TREE_TYPE (vr
->min
);
2339 fprintf (file
, "%s[", (vr
->type
== VR_ANTI_RANGE
) ? "~" : "");
2341 if (INTEGRAL_TYPE_P (type
)
2342 && !TYPE_UNSIGNED (type
)
2343 && vr
->min
== TYPE_MIN_VALUE (type
))
2344 fprintf (file
, "-INF");
2346 print_generic_expr (file
, vr
->min
, 0);
2348 fprintf (file
, ", ");
2350 if (INTEGRAL_TYPE_P (type
)
2351 && vr
->max
== TYPE_MAX_VALUE (type
))
2352 fprintf (file
, "+INF");
2354 print_generic_expr (file
, vr
->max
, 0);
2356 fprintf (file
, "]");
2363 fprintf (file
, " EQUIVALENCES: { ");
2365 EXECUTE_IF_SET_IN_BITMAP (vr
->equiv
, 0, i
, bi
)
2367 print_generic_expr (file
, ssa_name (i
), 0);
2368 fprintf (file
, " ");
2372 fprintf (file
, "} (%u elements)", c
);
2375 else if (vr
->type
== VR_VARYING
)
2376 fprintf (file
, "VARYING");
2378 fprintf (file
, "INVALID RANGE");
2382 /* Dump value range VR to stderr. */
2385 debug_value_range (value_range_t
*vr
)
2387 dump_value_range (stderr
, vr
);
2391 /* Dump value ranges of all SSA_NAMEs to FILE. */
2394 dump_all_value_ranges (FILE *file
)
2398 for (i
= 0; i
< num_ssa_names
; i
++)
2402 print_generic_expr (file
, ssa_name (i
), 0);
2403 fprintf (file
, ": ");
2404 dump_value_range (file
, vr_value
[i
]);
2405 fprintf (file
, "\n");
2409 fprintf (file
, "\n");
2413 /* Dump all value ranges to stderr. */
2416 debug_all_value_ranges (void)
2418 dump_all_value_ranges (stderr
);
2422 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
2423 create a new SSA name N and return the assertion assignment
2424 'V = ASSERT_EXPR <V, V OP W>'. */
2427 build_assert_expr_for (tree cond
, tree v
)
2431 gcc_assert (TREE_CODE (v
) == SSA_NAME
);
2432 n
= duplicate_ssa_name (v
, NULL_TREE
);
2434 if (COMPARISON_CLASS_P (cond
))
2436 tree a
= build2 (ASSERT_EXPR
, TREE_TYPE (v
), v
, cond
);
2437 assertion
= build2 (MODIFY_EXPR
, TREE_TYPE (v
), n
, a
);
2439 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
)
2441 /* Given !V, build the assignment N = false. */
2442 tree op0
= TREE_OPERAND (cond
, 0);
2443 gcc_assert (op0
== v
);
2444 assertion
= build2 (MODIFY_EXPR
, TREE_TYPE (v
), n
, boolean_false_node
);
2446 else if (TREE_CODE (cond
) == SSA_NAME
)
2448 /* Given V, build the assignment N = true. */
2449 gcc_assert (v
== cond
);
2450 assertion
= build2 (MODIFY_EXPR
, TREE_TYPE (v
), n
, boolean_true_node
);
2455 SSA_NAME_DEF_STMT (n
) = assertion
;
2457 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
2458 operand of the ASSERT_EXPR. Register the new name and the old one
2459 in the replacement table so that we can fix the SSA web after
2460 adding all the ASSERT_EXPRs. */
2461 register_new_name_mapping (n
, v
);
2467 /* Return false if EXPR is a predicate expression involving floating
2471 fp_predicate (tree expr
)
2473 return (COMPARISON_CLASS_P (expr
)
2474 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr
, 0))));
2478 /* If the range of values taken by OP can be inferred after STMT executes,
2479 return the comparison code (COMP_CODE_P) and value (VAL_P) that
2480 describes the inferred range. Return true if a range could be
2484 infer_value_range (tree stmt
, tree op
, enum tree_code
*comp_code_p
, tree
*val_p
)
2487 *comp_code_p
= ERROR_MARK
;
2489 /* Do not attempt to infer anything in names that flow through
2491 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op
))
2494 /* Similarly, don't infer anything from statements that may throw
2496 if (tree_could_throw_p (stmt
))
2499 /* If STMT is the last statement of a basic block with no
2500 successors, there is no point inferring anything about any of its
2501 operands. We would not be able to find a proper insertion point
2502 for the assertion, anyway. */
2503 if (stmt_ends_bb_p (stmt
) && EDGE_COUNT (bb_for_stmt (stmt
)->succs
) == 0)
2506 /* We can only assume that a pointer dereference will yield
2507 non-NULL if -fdelete-null-pointer-checks is enabled. */
2508 if (flag_delete_null_pointer_checks
&& POINTER_TYPE_P (TREE_TYPE (op
)))
2511 unsigned num_uses
, num_derefs
;
2513 count_uses_and_derefs (op
, stmt
, &num_uses
, &num_derefs
, &is_store
);
2516 *val_p
= build_int_cst (TREE_TYPE (op
), 0);
2517 *comp_code_p
= NE_EXPR
;
2526 void dump_asserts_for (FILE *, tree
);
2527 void debug_asserts_for (tree
);
2528 void dump_all_asserts (FILE *);
2529 void debug_all_asserts (void);
2531 /* Dump all the registered assertions for NAME to FILE. */
2534 dump_asserts_for (FILE *file
, tree name
)
2538 fprintf (file
, "Assertions to be inserted for ");
2539 print_generic_expr (file
, name
, 0);
2540 fprintf (file
, "\n");
2542 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
2545 fprintf (file
, "\t");
2546 print_generic_expr (file
, bsi_stmt (loc
->si
), 0);
2547 fprintf (file
, "\n\tBB #%d", loc
->bb
->index
);
2550 fprintf (file
, "\n\tEDGE %d->%d", loc
->e
->src
->index
,
2551 loc
->e
->dest
->index
);
2552 dump_edge_info (file
, loc
->e
, 0);
2554 fprintf (file
, "\n\tPREDICATE: ");
2555 print_generic_expr (file
, name
, 0);
2556 fprintf (file
, " %s ", tree_code_name
[(int)loc
->comp_code
]);
2557 print_generic_expr (file
, loc
->val
, 0);
2558 fprintf (file
, "\n\n");
2562 fprintf (file
, "\n");
2566 /* Dump all the registered assertions for NAME to stderr. */
2569 debug_asserts_for (tree name
)
2571 dump_asserts_for (stderr
, name
);
2575 /* Dump all the registered assertions for all the names to FILE. */
2578 dump_all_asserts (FILE *file
)
2583 fprintf (file
, "\nASSERT_EXPRs to be inserted\n\n");
2584 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
2585 dump_asserts_for (file
, ssa_name (i
));
2586 fprintf (file
, "\n");
2590 /* Dump all the registered assertions for all the names to stderr. */
2593 debug_all_asserts (void)
2595 dump_all_asserts (stderr
);
2599 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2600 'NAME COMP_CODE VAL' at a location that dominates block BB or
2601 E->DEST, then register this location as a possible insertion point
2602 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2604 BB, E and SI provide the exact insertion point for the new
2605 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2606 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2607 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2608 must not be NULL. */
2611 register_new_assert_for (tree name
,
2612 enum tree_code comp_code
,
2616 block_stmt_iterator si
)
2618 assert_locus_t n
, loc
, last_loc
;
2620 basic_block dest_bb
;
2622 #if defined ENABLE_CHECKING
2623 gcc_assert (bb
== NULL
|| e
== NULL
);
2626 gcc_assert (TREE_CODE (bsi_stmt (si
)) != COND_EXPR
2627 && TREE_CODE (bsi_stmt (si
)) != SWITCH_EXPR
);
2630 /* The new assertion A will be inserted at BB or E. We need to
2631 determine if the new location is dominated by a previously
2632 registered location for A. If we are doing an edge insertion,
2633 assume that A will be inserted at E->DEST. Note that this is not
2636 If E is a critical edge, it will be split. But even if E is
2637 split, the new block will dominate the same set of blocks that
2640 The reverse, however, is not true, blocks dominated by E->DEST
2641 will not be dominated by the new block created to split E. So,
2642 if the insertion location is on a critical edge, we will not use
2643 the new location to move another assertion previously registered
2644 at a block dominated by E->DEST. */
2645 dest_bb
= (bb
) ? bb
: e
->dest
;
2647 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2648 VAL at a block dominating DEST_BB, then we don't need to insert a new
2649 one. Similarly, if the same assertion already exists at a block
2650 dominated by DEST_BB and the new location is not on a critical
2651 edge, then update the existing location for the assertion (i.e.,
2652 move the assertion up in the dominance tree).
2654 Note, this is implemented as a simple linked list because there
2655 should not be more than a handful of assertions registered per
2656 name. If this becomes a performance problem, a table hashed by
2657 COMP_CODE and VAL could be implemented. */
2658 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
2663 if (loc
->comp_code
== comp_code
2665 || operand_equal_p (loc
->val
, val
, 0)))
2667 /* If the assertion NAME COMP_CODE VAL has already been
2668 registered at a basic block that dominates DEST_BB, then
2669 we don't need to insert the same assertion again. Note
2670 that we don't check strict dominance here to avoid
2671 replicating the same assertion inside the same basic
2672 block more than once (e.g., when a pointer is
2673 dereferenced several times inside a block).
2675 An exception to this rule are edge insertions. If the
2676 new assertion is to be inserted on edge E, then it will
2677 dominate all the other insertions that we may want to
2678 insert in DEST_BB. So, if we are doing an edge
2679 insertion, don't do this dominance check. */
2681 && dominated_by_p (CDI_DOMINATORS
, dest_bb
, loc
->bb
))
2684 /* Otherwise, if E is not a critical edge and DEST_BB
2685 dominates the existing location for the assertion, move
2686 the assertion up in the dominance tree by updating its
2687 location information. */
2688 if ((e
== NULL
|| !EDGE_CRITICAL_P (e
))
2689 && dominated_by_p (CDI_DOMINATORS
, loc
->bb
, dest_bb
))
2698 /* Update the last node of the list and move to the next one. */
2703 /* If we didn't find an assertion already registered for
2704 NAME COMP_CODE VAL, add a new one at the end of the list of
2705 assertions associated with NAME. */
2706 n
= XNEW (struct assert_locus_d
);
2710 n
->comp_code
= comp_code
;
2717 asserts_for
[SSA_NAME_VERSION (name
)] = n
;
2719 bitmap_set_bit (need_assert_for
, SSA_NAME_VERSION (name
));
2723 /* Try to register an edge assertion for SSA name NAME on edge E for
2724 the conditional jump pointed to by SI. Return true if an assertion
2725 for NAME could be registered. */
2728 register_edge_assert_for (tree name
, edge e
, block_stmt_iterator si
)
2731 enum tree_code comp_code
;
2733 stmt
= bsi_stmt (si
);
2735 /* Do not attempt to infer anything in names that flow through
2737 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name
))
2740 /* If NAME was not found in the sub-graph reachable from E, then
2741 there's nothing to do. */
2742 if (!TEST_BIT (found_in_subgraph
, SSA_NAME_VERSION (name
)))
2745 /* We found a use of NAME in the sub-graph rooted at E->DEST.
2746 Register an assertion for NAME according to the value that NAME
2748 if (TREE_CODE (stmt
) == COND_EXPR
)
2750 /* If BB ends in a COND_EXPR then NAME then we should insert
2751 the original predicate on EDGE_TRUE_VALUE and the
2752 opposite predicate on EDGE_FALSE_VALUE. */
2753 tree cond
= COND_EXPR_COND (stmt
);
2754 bool is_else_edge
= (e
->flags
& EDGE_FALSE_VALUE
) != 0;
2756 /* Predicates may be a single SSA name or NAME OP VAL. */
2759 /* If the predicate is a name, it must be NAME, in which
2760 case we create the predicate NAME == true or
2761 NAME == false accordingly. */
2762 comp_code
= EQ_EXPR
;
2763 val
= (is_else_edge
) ? boolean_false_node
: boolean_true_node
;
2767 /* Otherwise, we have a comparison of the form NAME COMP VAL
2768 or VAL COMP NAME. */
2769 if (name
== TREE_OPERAND (cond
, 1))
2771 /* If the predicate is of the form VAL COMP NAME, flip
2772 COMP around because we need to register NAME as the
2773 first operand in the predicate. */
2774 comp_code
= swap_tree_comparison (TREE_CODE (cond
));
2775 val
= TREE_OPERAND (cond
, 0);
2779 /* The comparison is of the form NAME COMP VAL, so the
2780 comparison code remains unchanged. */
2781 comp_code
= TREE_CODE (cond
);
2782 val
= TREE_OPERAND (cond
, 1);
2785 /* If we are inserting the assertion on the ELSE edge, we
2786 need to invert the sign comparison. */
2788 comp_code
= invert_tree_comparison (comp_code
, 0);
2790 /* Do not register always-false predicates. FIXME, this
2791 works around a limitation in fold() when dealing with
2792 enumerations. Given 'enum { N1, N2 } x;', fold will not
2793 fold 'if (x > N2)' to 'if (0)'. */
2794 if ((comp_code
== GT_EXPR
|| comp_code
== LT_EXPR
)
2795 && (INTEGRAL_TYPE_P (TREE_TYPE (val
))
2796 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (val
))))
2798 tree min
= TYPE_MIN_VALUE (TREE_TYPE (val
));
2799 tree max
= TYPE_MAX_VALUE (TREE_TYPE (val
));
2801 if (comp_code
== GT_EXPR
&& compare_values (val
, max
) == 0)
2804 if (comp_code
== LT_EXPR
&& compare_values (val
, min
) == 0)
2811 /* FIXME. Handle SWITCH_EXPR. */
2815 register_new_assert_for (name
, comp_code
, val
, NULL
, e
, si
);
2820 static bool find_assert_locations (basic_block bb
);
2822 /* Determine whether the outgoing edges of BB should receive an
2823 ASSERT_EXPR for each of the operands of BB's last statement. The
2824 last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2826 If any of the sub-graphs rooted at BB have an interesting use of
2827 the predicate operands, an assert location node is added to the
2828 list of assertions for the corresponding operands. */
2831 find_conditional_asserts (basic_block bb
)
2834 block_stmt_iterator last_si
;
2840 need_assert
= false;
2841 last_si
= bsi_last (bb
);
2842 last
= bsi_stmt (last_si
);
2844 /* Look for uses of the operands in each of the sub-graphs
2845 rooted at BB. We need to check each of the outgoing edges
2846 separately, so that we know what kind of ASSERT_EXPR to
2848 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2853 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
2854 Otherwise, when we finish traversing each of the sub-graphs, we
2855 won't know whether the variables were found in the sub-graphs or
2856 if they had been found in a block upstream from BB.
2858 This is actually a bad idea is some cases, particularly jump
2859 threading. Consider a CFG like the following:
2869 Assume that one or more operands in the conditional at the
2870 end of block 0 are used in a conditional in block 2, but not
2871 anywhere in block 1. In this case we will not insert any
2872 assert statements in block 1, which may cause us to miss
2873 opportunities to optimize, particularly for jump threading. */
2874 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
2875 RESET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
2877 /* Traverse the strictly dominated sub-graph rooted at E->DEST
2878 to determine if any of the operands in the conditional
2879 predicate are used. */
2881 need_assert
|= find_assert_locations (e
->dest
);
2883 /* Register the necessary assertions for each operand in the
2884 conditional predicate. */
2885 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
2886 need_assert
|= register_edge_assert_for (op
, e
, last_si
);
2889 /* Finally, indicate that we have found the operands in the
2891 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
2892 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
2898 /* Traverse all the statements in block BB looking for statements that
2899 may generate useful assertions for the SSA names in their operand.
2900 If a statement produces a useful assertion A for name N_i, then the
2901 list of assertions already generated for N_i is scanned to
2902 determine if A is actually needed.
2904 If N_i already had the assertion A at a location dominating the
2905 current location, then nothing needs to be done. Otherwise, the
2906 new location for A is recorded instead.
2908 1- For every statement S in BB, all the variables used by S are
2909 added to bitmap FOUND_IN_SUBGRAPH.
2911 2- If statement S uses an operand N in a way that exposes a known
2912 value range for N, then if N was not already generated by an
2913 ASSERT_EXPR, create a new assert location for N. For instance,
2914 if N is a pointer and the statement dereferences it, we can
2915 assume that N is not NULL.
2917 3- COND_EXPRs are a special case of #2. We can derive range
2918 information from the predicate but need to insert different
2919 ASSERT_EXPRs for each of the sub-graphs rooted at the
2920 conditional block. If the last statement of BB is a conditional
2921 expression of the form 'X op Y', then
2923 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
2925 b) If the conditional is the only entry point to the sub-graph
2926 corresponding to the THEN_CLAUSE, recurse into it. On
2927 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
2928 an ASSERT_EXPR is added for the corresponding variable.
2930 c) Repeat step (b) on the ELSE_CLAUSE.
2932 d) Mark X and Y in FOUND_IN_SUBGRAPH.
2941 In this case, an assertion on the THEN clause is useful to
2942 determine that 'a' is always 9 on that edge. However, an assertion
2943 on the ELSE clause would be unnecessary.
2945 4- If BB does not end in a conditional expression, then we recurse
2946 into BB's dominator children.
2948 At the end of the recursive traversal, every SSA name will have a
2949 list of locations where ASSERT_EXPRs should be added. When a new
2950 location for name N is found, it is registered by calling
2951 register_new_assert_for. That function keeps track of all the
2952 registered assertions to prevent adding unnecessary assertions.
2953 For instance, if a pointer P_4 is dereferenced more than once in a
2954 dominator tree, only the location dominating all the dereference of
2955 P_4 will receive an ASSERT_EXPR.
2957 If this function returns true, then it means that there are names
2958 for which we need to generate ASSERT_EXPRs. Those assertions are
2959 inserted by process_assert_insertions.
2961 TODO. Handle SWITCH_EXPR. */
2964 find_assert_locations (basic_block bb
)
2966 block_stmt_iterator si
;
2971 if (TEST_BIT (blocks_visited
, bb
->index
))
2974 SET_BIT (blocks_visited
, bb
->index
);
2976 need_assert
= false;
2978 /* Traverse all PHI nodes in BB marking used operands. */
2979 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
2981 use_operand_p arg_p
;
2984 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_USE
)
2986 tree arg
= USE_FROM_PTR (arg_p
);
2987 if (TREE_CODE (arg
) == SSA_NAME
)
2989 gcc_assert (is_gimple_reg (PHI_RESULT (phi
)));
2990 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (arg
));
2995 /* Traverse all the statements in BB marking used names and looking
2996 for statements that may infer assertions for their used operands. */
2998 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
3003 stmt
= bsi_stmt (si
);
3005 /* See if we can derive an assertion for any of STMT's operands. */
3006 FOR_EACH_SSA_TREE_OPERAND (op
, stmt
, i
, SSA_OP_USE
)
3009 enum tree_code comp_code
;
3011 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
3012 the sub-graph of a conditional block, when we return from
3013 this recursive walk, our parent will use the
3014 FOUND_IN_SUBGRAPH bitset to determine if one of the
3015 operands it was looking for was present in the sub-graph. */
3016 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3018 /* If OP is used in such a way that we can infer a value
3019 range for it, and we don't find a previous assertion for
3020 it, create a new assertion location node for OP. */
3021 if (infer_value_range (stmt
, op
, &comp_code
, &value
))
3023 /* If we are able to infer a nonzero value range for OP,
3024 then walk backwards through the use-def chain to see if OP
3025 was set via a typecast.
3027 If so, then we can also infer a nonzero value range
3028 for the operand of the NOP_EXPR. */
3029 if (comp_code
== NE_EXPR
&& integer_zerop (value
))
3032 tree def_stmt
= SSA_NAME_DEF_STMT (t
);
3034 while (TREE_CODE (def_stmt
) == MODIFY_EXPR
3035 && TREE_CODE (TREE_OPERAND (def_stmt
, 1)) == NOP_EXPR
3036 && TREE_CODE (TREE_OPERAND (TREE_OPERAND (def_stmt
, 1), 0)) == SSA_NAME
3037 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (def_stmt
, 1), 0))))
3039 t
= TREE_OPERAND (TREE_OPERAND (def_stmt
, 1), 0);
3040 def_stmt
= SSA_NAME_DEF_STMT (t
);
3042 /* Note we want to register the assert for the
3043 operand of the NOP_EXPR after SI, not after the
3045 if (! has_single_use (t
))
3047 register_new_assert_for (t
, comp_code
, value
,
3054 /* If OP is used only once, namely in this STMT, don't
3055 bother creating an ASSERT_EXPR for it. Such an
3056 ASSERT_EXPR would do nothing but increase compile time. */
3057 if (!has_single_use (op
))
3059 register_new_assert_for (op
, comp_code
, value
, bb
, NULL
, si
);
3065 /* Remember the last statement of the block. */
3069 /* If BB's last statement is a conditional expression
3070 involving integer operands, recurse into each of the sub-graphs
3071 rooted at BB to determine if we need to add ASSERT_EXPRs. */
3073 && TREE_CODE (last
) == COND_EXPR
3074 && !fp_predicate (COND_EXPR_COND (last
))
3075 && !ZERO_SSA_OPERANDS (last
, SSA_OP_USE
))
3076 need_assert
|= find_conditional_asserts (bb
);
3078 /* Recurse into the dominator children of BB. */
3079 for (son
= first_dom_son (CDI_DOMINATORS
, bb
);
3081 son
= next_dom_son (CDI_DOMINATORS
, son
))
3082 need_assert
|= find_assert_locations (son
);
3088 /* Create an ASSERT_EXPR for NAME and insert it in the location
3089 indicated by LOC. Return true if we made any edge insertions. */
3092 process_assert_insertions_for (tree name
, assert_locus_t loc
)
3094 /* Build the comparison expression NAME_i COMP_CODE VAL. */
3095 tree stmt
, cond
, assert_expr
;
3099 cond
= build2 (loc
->comp_code
, boolean_type_node
, name
, loc
->val
);
3100 assert_expr
= build_assert_expr_for (cond
, name
);
3104 /* We have been asked to insert the assertion on an edge. This
3105 is used only by COND_EXPR and SWITCH_EXPR assertions. */
3106 #if defined ENABLE_CHECKING
3107 gcc_assert (TREE_CODE (bsi_stmt (loc
->si
)) == COND_EXPR
3108 || TREE_CODE (bsi_stmt (loc
->si
)) == SWITCH_EXPR
);
3111 bsi_insert_on_edge (loc
->e
, assert_expr
);
3115 /* Otherwise, we can insert right after LOC->SI iff the
3116 statement must not be the last statement in the block. */
3117 stmt
= bsi_stmt (loc
->si
);
3118 if (!stmt_ends_bb_p (stmt
))
3120 bsi_insert_after (&loc
->si
, assert_expr
, BSI_SAME_STMT
);
3124 /* If STMT must be the last statement in BB, we can only insert new
3125 assertions on the non-abnormal edge out of BB. Note that since
3126 STMT is not control flow, there may only be one non-abnormal edge
3128 FOR_EACH_EDGE (e
, ei
, loc
->bb
->succs
)
3129 if (!(e
->flags
& EDGE_ABNORMAL
))
3131 bsi_insert_on_edge (e
, assert_expr
);
3139 /* Process all the insertions registered for every name N_i registered
3140 in NEED_ASSERT_FOR. The list of assertions to be inserted are
3141 found in ASSERTS_FOR[i]. */
3144 process_assert_insertions (void)
3148 bool update_edges_p
= false;
3149 int num_asserts
= 0;
3151 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3152 dump_all_asserts (dump_file
);
3154 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
3156 assert_locus_t loc
= asserts_for
[i
];
3161 assert_locus_t next
= loc
->next
;
3162 update_edges_p
|= process_assert_insertions_for (ssa_name (i
), loc
);
3170 bsi_commit_edge_inserts ();
3172 if (dump_file
&& (dump_flags
& TDF_STATS
))
3173 fprintf (dump_file
, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
3178 /* Traverse the flowgraph looking for conditional jumps to insert range
3179 expressions. These range expressions are meant to provide information
3180 to optimizations that need to reason in terms of value ranges. They
3181 will not be expanded into RTL. For instance, given:
3190 this pass will transform the code into:
3196 x = ASSERT_EXPR <x, x < y>
3201 y = ASSERT_EXPR <y, x <= y>
3205 The idea is that once copy and constant propagation have run, other
3206 optimizations will be able to determine what ranges of values can 'x'
3207 take in different paths of the code, simply by checking the reaching
3208 definition of 'x'. */
3211 insert_range_assertions (void)
3217 found_in_subgraph
= sbitmap_alloc (num_ssa_names
);
3218 sbitmap_zero (found_in_subgraph
);
3220 blocks_visited
= sbitmap_alloc (last_basic_block
);
3221 sbitmap_zero (blocks_visited
);
3223 need_assert_for
= BITMAP_ALLOC (NULL
);
3224 asserts_for
= XNEWVEC (assert_locus_t
, num_ssa_names
);
3225 memset (asserts_for
, 0, num_ssa_names
* sizeof (assert_locus_t
));
3227 calculate_dominance_info (CDI_DOMINATORS
);
3229 update_ssa_p
= false;
3230 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
3231 if (find_assert_locations (e
->dest
))
3232 update_ssa_p
= true;
3236 process_assert_insertions ();
3237 update_ssa (TODO_update_ssa_no_phi
);
3240 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3242 fprintf (dump_file
, "\nSSA form after inserting ASSERT_EXPRs\n");
3243 dump_function_to_file (current_function_decl
, dump_file
, dump_flags
);
3246 sbitmap_free (found_in_subgraph
);
3248 BITMAP_FREE (need_assert_for
);
3252 /* Convert range assertion expressions into the implied copies and
3253 copy propagate away the copies. Doing the trivial copy propagation
3254 here avoids the need to run the full copy propagation pass after
3257 FIXME, this will eventually lead to copy propagation removing the
3258 names that had useful range information attached to them. For
3259 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
3260 then N_i will have the range [3, +INF].
3262 However, by converting the assertion into the implied copy
3263 operation N_i = N_j, we will then copy-propagate N_j into the uses
3264 of N_i and lose the range information. We may want to hold on to
3265 ASSERT_EXPRs a little while longer as the ranges could be used in
3266 things like jump threading.
3268 The problem with keeping ASSERT_EXPRs around is that passes after
3269 VRP need to handle them appropriately.
3271 Another approach would be to make the range information a first
3272 class property of the SSA_NAME so that it can be queried from
3273 any pass. This is made somewhat more complex by the need for
3274 multiple ranges to be associated with one SSA_NAME. */
3277 remove_range_assertions (void)
3280 block_stmt_iterator si
;
3282 /* Note that the BSI iterator bump happens at the bottom of the
3283 loop and no bump is necessary if we're removing the statement
3284 referenced by the current BSI. */
3286 for (si
= bsi_start (bb
); !bsi_end_p (si
);)
3288 tree stmt
= bsi_stmt (si
);
3291 if (TREE_CODE (stmt
) == MODIFY_EXPR
3292 && TREE_CODE (TREE_OPERAND (stmt
, 1)) == ASSERT_EXPR
)
3294 tree rhs
= TREE_OPERAND (stmt
, 1), var
;
3295 tree cond
= fold (ASSERT_EXPR_COND (rhs
));
3296 use_operand_p use_p
;
3297 imm_use_iterator iter
;
3299 gcc_assert (cond
!= boolean_false_node
);
3301 /* Propagate the RHS into every use of the LHS. */
3302 var
= ASSERT_EXPR_VAR (rhs
);
3303 FOR_EACH_IMM_USE_STMT (use_stmt
, iter
, TREE_OPERAND (stmt
, 0))
3304 FOR_EACH_IMM_USE_ON_STMT (use_p
, iter
)
3306 SET_USE (use_p
, var
);
3307 gcc_assert (TREE_CODE (var
) == SSA_NAME
);
3310 /* And finally, remove the copy, it is not needed. */
3311 bsi_remove (&si
, true);
3317 sbitmap_free (blocks_visited
);
3321 /* Return true if STMT is interesting for VRP. */
3324 stmt_interesting_for_vrp (tree stmt
)
3326 if (TREE_CODE (stmt
) == PHI_NODE
3327 && is_gimple_reg (PHI_RESULT (stmt
))
3328 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))
3329 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))))
3331 else if (TREE_CODE (stmt
) == MODIFY_EXPR
)
3333 tree lhs
= TREE_OPERAND (stmt
, 0);
3334 tree rhs
= TREE_OPERAND (stmt
, 1);
3336 /* In general, assignments with virtual operands are not useful
3337 for deriving ranges, with the obvious exception of calls to
3338 builtin functions. */
3339 if (TREE_CODE (lhs
) == SSA_NAME
3340 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
3341 || POINTER_TYPE_P (TREE_TYPE (lhs
)))
3342 && ((TREE_CODE (rhs
) == CALL_EXPR
3343 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == ADDR_EXPR
3344 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0))
3345 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0)))
3346 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
)))
3349 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
3356 /* Initialize local data structures for VRP. */
3359 vrp_initialize (void)
3363 vr_value
= XNEWVEC (value_range_t
*, num_ssa_names
);
3364 memset (vr_value
, 0, num_ssa_names
* sizeof (value_range_t
*));
3368 block_stmt_iterator si
;
3371 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3373 if (!stmt_interesting_for_vrp (phi
))
3375 tree lhs
= PHI_RESULT (phi
);
3376 set_value_range_to_varying (get_value_range (lhs
));
3377 DONT_SIMULATE_AGAIN (phi
) = true;
3380 DONT_SIMULATE_AGAIN (phi
) = false;
3383 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
3385 tree stmt
= bsi_stmt (si
);
3387 if (!stmt_interesting_for_vrp (stmt
))
3391 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, i
, SSA_OP_DEF
)
3392 set_value_range_to_varying (get_value_range (def
));
3393 DONT_SIMULATE_AGAIN (stmt
) = true;
3397 DONT_SIMULATE_AGAIN (stmt
) = false;
3404 /* Visit assignment STMT. If it produces an interesting range, record
3405 the SSA name in *OUTPUT_P. */
3407 static enum ssa_prop_result
3408 vrp_visit_assignment (tree stmt
, tree
*output_p
)
3413 lhs
= TREE_OPERAND (stmt
, 0);
3414 rhs
= TREE_OPERAND (stmt
, 1);
3416 /* We only keep track of ranges in integral and pointer types. */
3417 if (TREE_CODE (lhs
) == SSA_NAME
3418 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
3419 /* It is valid to have NULL MIN/MAX values on a type. See
3420 build_range_type. */
3421 && TYPE_MIN_VALUE (TREE_TYPE (lhs
))
3422 && TYPE_MAX_VALUE (TREE_TYPE (lhs
)))
3423 || POINTER_TYPE_P (TREE_TYPE (lhs
))))
3426 value_range_t new_vr
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
3428 extract_range_from_expr (&new_vr
, rhs
);
3430 /* If STMT is inside a loop, we may be able to know something
3431 else about the range of LHS by examining scalar evolution
3433 if (current_loops
&& (l
= loop_containing_stmt (stmt
)))
3434 adjust_range_with_scev (&new_vr
, l
, stmt
, lhs
);
3436 if (update_value_range (lhs
, &new_vr
))
3440 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3442 fprintf (dump_file
, "Found new range for ");
3443 print_generic_expr (dump_file
, lhs
, 0);
3444 fprintf (dump_file
, ": ");
3445 dump_value_range (dump_file
, &new_vr
);
3446 fprintf (dump_file
, "\n\n");
3449 if (new_vr
.type
== VR_VARYING
)
3450 return SSA_PROP_VARYING
;
3452 return SSA_PROP_INTERESTING
;
3455 return SSA_PROP_NOT_INTERESTING
;
3458 /* Every other statement produces no useful ranges. */
3459 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
3460 set_value_range_to_varying (get_value_range (def
));
3462 return SSA_PROP_VARYING
;
3466 /* Compare all the value ranges for names equivalent to VAR with VAL
3467 using comparison code COMP. Return the same value returned by
3468 compare_range_with_value. */
3471 compare_name_with_value (enum tree_code comp
, tree var
, tree val
)
3478 t
= retval
= NULL_TREE
;
3480 /* Get the set of equivalences for VAR. */
3481 e
= get_value_range (var
)->equiv
;
3483 /* Add VAR to its own set of equivalences so that VAR's value range
3484 is processed by this loop (otherwise, we would have to replicate
3485 the body of the loop just to check VAR's value range). */
3486 bitmap_set_bit (e
, SSA_NAME_VERSION (var
));
3488 EXECUTE_IF_SET_IN_BITMAP (e
, 0, i
, bi
)
3490 value_range_t equiv_vr
= *(vr_value
[i
]);
3492 /* If name N_i does not have a valid range, use N_i as its own
3493 range. This allows us to compare against names that may
3494 have N_i in their ranges. */
3495 if (equiv_vr
.type
== VR_VARYING
|| equiv_vr
.type
== VR_UNDEFINED
)
3497 equiv_vr
.type
= VR_RANGE
;
3498 equiv_vr
.min
= ssa_name (i
);
3499 equiv_vr
.max
= ssa_name (i
);
3502 t
= compare_range_with_value (comp
, &equiv_vr
, val
);
3505 /* All the ranges should compare the same against VAL. */
3506 gcc_assert (retval
== NULL
|| t
== retval
);
3511 /* Remove VAR from its own equivalence set. */
3512 bitmap_clear_bit (e
, SSA_NAME_VERSION (var
));
3517 /* We couldn't find a non-NULL value for the predicate. */
3522 /* Given a comparison code COMP and names N1 and N2, compare all the
3523 ranges equivalent to N1 against all the ranges equivalent to N2
3524 to determine the value of N1 COMP N2. Return the same value
3525 returned by compare_ranges. */
3528 compare_names (enum tree_code comp
, tree n1
, tree n2
)
3532 bitmap_iterator bi1
, bi2
;
3535 /* Compare the ranges of every name equivalent to N1 against the
3536 ranges of every name equivalent to N2. */
3537 e1
= get_value_range (n1
)->equiv
;
3538 e2
= get_value_range (n2
)->equiv
;
3540 /* Add N1 and N2 to their own set of equivalences to avoid
3541 duplicating the body of the loop just to check N1 and N2
3543 bitmap_set_bit (e1
, SSA_NAME_VERSION (n1
));
3544 bitmap_set_bit (e2
, SSA_NAME_VERSION (n2
));
3546 /* If the equivalence sets have a common intersection, then the two
3547 names can be compared without checking their ranges. */
3548 if (bitmap_intersect_p (e1
, e2
))
3550 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3551 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3553 return (comp
== EQ_EXPR
|| comp
== GE_EXPR
|| comp
== LE_EXPR
)
3555 : boolean_false_node
;
3558 /* Otherwise, compare all the equivalent ranges. First, add N1 and
3559 N2 to their own set of equivalences to avoid duplicating the body
3560 of the loop just to check N1 and N2 ranges. */
3561 EXECUTE_IF_SET_IN_BITMAP (e1
, 0, i1
, bi1
)
3563 value_range_t vr1
= *(vr_value
[i1
]);
3565 /* If the range is VARYING or UNDEFINED, use the name itself. */
3566 if (vr1
.type
== VR_VARYING
|| vr1
.type
== VR_UNDEFINED
)
3568 vr1
.type
= VR_RANGE
;
3569 vr1
.min
= ssa_name (i1
);
3570 vr1
.max
= ssa_name (i1
);
3573 t
= retval
= NULL_TREE
;
3574 EXECUTE_IF_SET_IN_BITMAP (e2
, 0, i2
, bi2
)
3576 value_range_t vr2
= *(vr_value
[i2
]);
3578 if (vr2
.type
== VR_VARYING
|| vr2
.type
== VR_UNDEFINED
)
3580 vr2
.type
= VR_RANGE
;
3581 vr2
.min
= ssa_name (i2
);
3582 vr2
.max
= ssa_name (i2
);
3585 t
= compare_ranges (comp
, &vr1
, &vr2
);
3588 /* All the ranges in the equivalent sets should compare
3590 gcc_assert (retval
== NULL
|| t
== retval
);
3597 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3598 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3603 /* None of the equivalent ranges are useful in computing this
3605 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3606 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3611 /* Given a conditional predicate COND, try to determine if COND yields
3612 true or false based on the value ranges of its operands. Return
3613 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3614 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3615 NULL if the conditional cannot be evaluated at compile time.
3617 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3618 the operands in COND are used when trying to compute its value.
3619 This is only used during final substitution. During propagation,
3620 we only check the range of each variable and not its equivalents. */
3623 vrp_evaluate_conditional (tree cond
, bool use_equiv_p
)
3625 gcc_assert (TREE_CODE (cond
) == SSA_NAME
3626 || TREE_CODE_CLASS (TREE_CODE (cond
)) == tcc_comparison
);
3628 if (TREE_CODE (cond
) == SSA_NAME
)
3634 retval
= compare_name_with_value (NE_EXPR
, cond
, boolean_false_node
);
3637 value_range_t
*vr
= get_value_range (cond
);
3638 retval
= compare_range_with_value (NE_EXPR
, vr
, boolean_false_node
);
3641 /* If COND has a known boolean range, return it. */
3645 /* Otherwise, if COND has a symbolic range of exactly one value,
3647 vr
= get_value_range (cond
);
3648 if (vr
->type
== VR_RANGE
&& vr
->min
== vr
->max
)
3653 tree op0
= TREE_OPERAND (cond
, 0);
3654 tree op1
= TREE_OPERAND (cond
, 1);
3656 /* We only deal with integral and pointer types. */
3657 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
3658 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
3663 if (TREE_CODE (op0
) == SSA_NAME
&& TREE_CODE (op1
) == SSA_NAME
)
3664 return compare_names (TREE_CODE (cond
), op0
, op1
);
3665 else if (TREE_CODE (op0
) == SSA_NAME
)
3666 return compare_name_with_value (TREE_CODE (cond
), op0
, op1
);
3667 else if (TREE_CODE (op1
) == SSA_NAME
)
3668 return compare_name_with_value (
3669 swap_tree_comparison (TREE_CODE (cond
)), op1
, op0
);
3673 value_range_t
*vr0
, *vr1
;
3675 vr0
= (TREE_CODE (op0
) == SSA_NAME
) ? get_value_range (op0
) : NULL
;
3676 vr1
= (TREE_CODE (op1
) == SSA_NAME
) ? get_value_range (op1
) : NULL
;
3679 return compare_ranges (TREE_CODE (cond
), vr0
, vr1
);
3680 else if (vr0
&& vr1
== NULL
)
3681 return compare_range_with_value (TREE_CODE (cond
), vr0
, op1
);
3682 else if (vr0
== NULL
&& vr1
)
3683 return compare_range_with_value (
3684 swap_tree_comparison (TREE_CODE (cond
)), vr1
, op0
);
3688 /* Anything else cannot be computed statically. */
3693 /* Visit conditional statement STMT. If we can determine which edge
3694 will be taken out of STMT's basic block, record it in
3695 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3696 SSA_PROP_VARYING. */
3698 static enum ssa_prop_result
3699 vrp_visit_cond_stmt (tree stmt
, edge
*taken_edge_p
)
3703 *taken_edge_p
= NULL
;
3705 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3706 add ASSERT_EXPRs for them. */
3707 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
3708 return SSA_PROP_VARYING
;
3710 cond
= COND_EXPR_COND (stmt
);
3712 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3717 fprintf (dump_file
, "\nVisiting conditional with predicate: ");
3718 print_generic_expr (dump_file
, cond
, 0);
3719 fprintf (dump_file
, "\nWith known ranges\n");
3721 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, i
, SSA_OP_USE
)
3723 fprintf (dump_file
, "\t");
3724 print_generic_expr (dump_file
, use
, 0);
3725 fprintf (dump_file
, ": ");
3726 dump_value_range (dump_file
, vr_value
[SSA_NAME_VERSION (use
)]);
3729 fprintf (dump_file
, "\n");
3732 /* Compute the value of the predicate COND by checking the known
3733 ranges of each of its operands.
3735 Note that we cannot evaluate all the equivalent ranges here
3736 because those ranges may not yet be final and with the current
3737 propagation strategy, we cannot determine when the value ranges
3738 of the names in the equivalence set have changed.
3740 For instance, given the following code fragment
3744 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3748 Assume that on the first visit to i_14, i_5 has the temporary
3749 range [8, 8] because the second argument to the PHI function is
3750 not yet executable. We derive the range ~[0, 0] for i_14 and the
3751 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3752 the first time, since i_14 is equivalent to the range [8, 8], we
3753 determine that the predicate is always false.
3755 On the next round of propagation, i_13 is determined to be
3756 VARYING, which causes i_5 to drop down to VARYING. So, another
3757 visit to i_14 is scheduled. In this second visit, we compute the
3758 exact same range and equivalence set for i_14, namely ~[0, 0] and
3759 { i_5 }. But we did not have the previous range for i_5
3760 registered, so vrp_visit_assignment thinks that the range for
3761 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3762 is not visited again, which stops propagation from visiting
3763 statements in the THEN clause of that if().
3765 To properly fix this we would need to keep the previous range
3766 value for the names in the equivalence set. This way we would've
3767 discovered that from one visit to the other i_5 changed from
3768 range [8, 8] to VR_VARYING.
3770 However, fixing this apparent limitation may not be worth the
3771 additional checking. Testing on several code bases (GCC, DLV,
3772 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3773 4 more predicates folded in SPEC. */
3774 val
= vrp_evaluate_conditional (cond
, false);
3776 *taken_edge_p
= find_taken_edge (bb_for_stmt (stmt
), val
);
3778 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3780 fprintf (dump_file
, "\nPredicate evaluates to: ");
3781 if (val
== NULL_TREE
)
3782 fprintf (dump_file
, "DON'T KNOW\n");
3784 print_generic_stmt (dump_file
, val
, 0);
3787 return (*taken_edge_p
) ? SSA_PROP_INTERESTING
: SSA_PROP_VARYING
;
3791 /* Evaluate statement STMT. If the statement produces a useful range,
3792 return SSA_PROP_INTERESTING and record the SSA name with the
3793 interesting range into *OUTPUT_P.
3795 If STMT is a conditional branch and we can determine its truth
3796 value, the taken edge is recorded in *TAKEN_EDGE_P.
3798 If STMT produces a varying value, return SSA_PROP_VARYING. */
3800 static enum ssa_prop_result
3801 vrp_visit_stmt (tree stmt
, edge
*taken_edge_p
, tree
*output_p
)
3807 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3809 fprintf (dump_file
, "\nVisiting statement:\n");
3810 print_generic_stmt (dump_file
, stmt
, dump_flags
);
3811 fprintf (dump_file
, "\n");
3814 ann
= stmt_ann (stmt
);
3815 if (TREE_CODE (stmt
) == MODIFY_EXPR
)
3817 tree rhs
= TREE_OPERAND (stmt
, 1);
3819 /* In general, assignments with virtual operands are not useful
3820 for deriving ranges, with the obvious exception of calls to
3821 builtin functions. */
3822 if ((TREE_CODE (rhs
) == CALL_EXPR
3823 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == ADDR_EXPR
3824 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0))
3825 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0)))
3826 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
3827 return vrp_visit_assignment (stmt
, output_p
);
3829 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
3830 return vrp_visit_cond_stmt (stmt
, taken_edge_p
);
3832 /* All other statements produce nothing of interest for VRP, so mark
3833 their outputs varying and prevent further simulation. */
3834 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
3835 set_value_range_to_varying (get_value_range (def
));
3837 return SSA_PROP_VARYING
;
3841 /* Meet operation for value ranges. Given two value ranges VR0 and
3842 VR1, store in VR0 the result of meeting VR0 and VR1.
3844 The meeting rules are as follows:
3846 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
3848 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
3849 union of VR0 and VR1. */
3852 vrp_meet (value_range_t
*vr0
, value_range_t
*vr1
)
3854 if (vr0
->type
== VR_UNDEFINED
)
3856 copy_value_range (vr0
, vr1
);
3860 if (vr1
->type
== VR_UNDEFINED
)
3862 /* Nothing to do. VR0 already has the resulting range. */
3866 if (vr0
->type
== VR_VARYING
)
3868 /* Nothing to do. VR0 already has the resulting range. */
3872 if (vr1
->type
== VR_VARYING
)
3874 set_value_range_to_varying (vr0
);
3878 if (vr0
->type
== VR_RANGE
&& vr1
->type
== VR_RANGE
)
3880 /* If VR0 and VR1 have a non-empty intersection, compute the
3881 union of both ranges. */
3882 if (value_ranges_intersect_p (vr0
, vr1
))
3887 /* The lower limit of the new range is the minimum of the
3888 two ranges. If they cannot be compared, the result is
3890 cmp
= compare_values (vr0
->min
, vr1
->min
);
3891 if (cmp
== 0 || cmp
== 1)
3897 set_value_range_to_varying (vr0
);
3901 /* Similarly, the upper limit of the new range is the
3902 maximum of the two ranges. If they cannot be compared,
3903 the result is VARYING. */
3904 cmp
= compare_values (vr0
->max
, vr1
->max
);
3905 if (cmp
== 0 || cmp
== -1)
3911 set_value_range_to_varying (vr0
);
3915 /* The resulting set of equivalences is the intersection of
3917 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
3918 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
3919 else if (vr0
->equiv
&& !vr1
->equiv
)
3920 bitmap_clear (vr0
->equiv
);
3922 set_value_range (vr0
, vr0
->type
, min
, max
, vr0
->equiv
);
3927 else if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
3929 /* Two anti-ranges meet only if they are both identical. */
3930 if (compare_values (vr0
->min
, vr1
->min
) == 0
3931 && compare_values (vr0
->max
, vr1
->max
) == 0
3932 && compare_values (vr0
->min
, vr0
->max
) == 0)
3934 /* The resulting set of equivalences is the intersection of
3936 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
3937 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
3938 else if (vr0
->equiv
&& !vr1
->equiv
)
3939 bitmap_clear (vr0
->equiv
);
3944 else if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
3946 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
3947 meet only if the ranges have an empty intersection. The
3948 result of the meet operation is the anti-range. */
3949 if (!symbolic_range_p (vr0
)
3950 && !symbolic_range_p (vr1
)
3951 && !value_ranges_intersect_p (vr0
, vr1
))
3953 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
3954 set. We need to compute the intersection of the two
3955 equivalence sets. */
3956 if (vr1
->type
== VR_ANTI_RANGE
)
3957 set_value_range (vr0
, vr1
->type
, vr1
->min
, vr1
->max
, vr0
->equiv
);
3959 /* The resulting set of equivalences is the intersection of
3961 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
3962 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
3963 else if (vr0
->equiv
&& !vr1
->equiv
)
3964 bitmap_clear (vr0
->equiv
);
3975 /* The two range VR0 and VR1 do not meet. Before giving up and
3976 setting the result to VARYING, see if we can at least derive a
3977 useful anti-range. FIXME, all this nonsense about distinguishing
3978 anti-ranges from ranges is necessary because of the odd
3979 semantics of range_includes_zero_p and friends. */
3980 if (!symbolic_range_p (vr0
)
3981 && ((vr0
->type
== VR_RANGE
&& !range_includes_zero_p (vr0
))
3982 || (vr0
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr0
)))
3983 && !symbolic_range_p (vr1
)
3984 && ((vr1
->type
== VR_RANGE
&& !range_includes_zero_p (vr1
))
3985 || (vr1
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr1
))))
3987 set_value_range_to_nonnull (vr0
, TREE_TYPE (vr0
->min
));
3989 /* Since this meet operation did not result from the meeting of
3990 two equivalent names, VR0 cannot have any equivalences. */
3992 bitmap_clear (vr0
->equiv
);
3995 set_value_range_to_varying (vr0
);
3999 /* Visit all arguments for PHI node PHI that flow through executable
4000 edges. If a valid value range can be derived from all the incoming
4001 value ranges, set a new range for the LHS of PHI. */
4003 static enum ssa_prop_result
4004 vrp_visit_phi_node (tree phi
)
4007 tree lhs
= PHI_RESULT (phi
);
4008 value_range_t
*lhs_vr
= get_value_range (lhs
);
4009 value_range_t vr_result
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
4011 copy_value_range (&vr_result
, lhs_vr
);
4013 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4015 fprintf (dump_file
, "\nVisiting PHI node: ");
4016 print_generic_expr (dump_file
, phi
, dump_flags
);
4019 for (i
= 0; i
< PHI_NUM_ARGS (phi
); i
++)
4021 edge e
= PHI_ARG_EDGE (phi
, i
);
4023 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4026 "\n Argument #%d (%d -> %d %sexecutable)\n",
4027 i
, e
->src
->index
, e
->dest
->index
,
4028 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
4031 if (e
->flags
& EDGE_EXECUTABLE
)
4033 tree arg
= PHI_ARG_DEF (phi
, i
);
4034 value_range_t vr_arg
;
4036 if (TREE_CODE (arg
) == SSA_NAME
)
4037 vr_arg
= *(get_value_range (arg
));
4040 vr_arg
.type
= VR_RANGE
;
4043 vr_arg
.equiv
= NULL
;
4046 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4048 fprintf (dump_file
, "\t");
4049 print_generic_expr (dump_file
, arg
, dump_flags
);
4050 fprintf (dump_file
, "\n\tValue: ");
4051 dump_value_range (dump_file
, &vr_arg
);
4052 fprintf (dump_file
, "\n");
4055 vrp_meet (&vr_result
, &vr_arg
);
4057 if (vr_result
.type
== VR_VARYING
)
4062 if (vr_result
.type
== VR_VARYING
)
4065 /* To prevent infinite iterations in the algorithm, derive ranges
4066 when the new value is slightly bigger or smaller than the
4068 if (lhs_vr
->type
== VR_RANGE
&& vr_result
.type
== VR_RANGE
)
4070 if (!POINTER_TYPE_P (TREE_TYPE (lhs
)))
4072 int cmp_min
= compare_values (lhs_vr
->min
, vr_result
.min
);
4073 int cmp_max
= compare_values (lhs_vr
->max
, vr_result
.max
);
4075 /* If the new minimum is smaller or larger than the previous
4076 one, go all the way to -INF. In the first case, to avoid
4077 iterating millions of times to reach -INF, and in the
4078 other case to avoid infinite bouncing between different
4080 if (cmp_min
> 0 || cmp_min
< 0)
4081 vr_result
.min
= TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
));
4083 /* Similarly, if the new maximum is smaller or larger than
4084 the previous one, go all the way to +INF. */
4085 if (cmp_max
< 0 || cmp_max
> 0)
4086 vr_result
.max
= TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
));
4088 /* If we ended up with a (-INF, +INF) range, set it to
4090 if (vr_result
.min
== TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
))
4091 && vr_result
.max
== TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
)))
4096 /* If the new range is different than the previous value, keep
4098 if (update_value_range (lhs
, &vr_result
))
4099 return SSA_PROP_INTERESTING
;
4101 /* Nothing changed, don't add outgoing edges. */
4102 return SSA_PROP_NOT_INTERESTING
;
4104 /* No match found. Set the LHS to VARYING. */
4106 set_value_range_to_varying (lhs_vr
);
4107 return SSA_PROP_VARYING
;
4110 /* Simplify a division or modulo operator to a right shift or
4111 bitwise and if the first operand is unsigned or is greater
4112 than zero and the second operand is an exact power of two. */
4115 simplify_div_or_mod_using_ranges (tree stmt
, tree rhs
, enum tree_code rhs_code
)
4118 tree op
= TREE_OPERAND (rhs
, 0);
4119 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
4121 if (TYPE_UNSIGNED (TREE_TYPE (op
)))
4123 val
= integer_one_node
;
4127 val
= compare_range_with_value (GT_EXPR
, vr
, integer_zero_node
);
4130 if (val
&& integer_onep (val
))
4133 tree op0
= TREE_OPERAND (rhs
, 0);
4134 tree op1
= TREE_OPERAND (rhs
, 1);
4136 if (rhs_code
== TRUNC_DIV_EXPR
)
4138 t
= build_int_cst (NULL_TREE
, tree_log2 (op1
));
4139 t
= build2 (RSHIFT_EXPR
, TREE_TYPE (op0
), op0
, t
);
4143 t
= build_int_cst (TREE_TYPE (op1
), 1);
4144 t
= int_const_binop (MINUS_EXPR
, op1
, t
, 0);
4145 t
= fold_convert (TREE_TYPE (op0
), t
);
4146 t
= build2 (BIT_AND_EXPR
, TREE_TYPE (op0
), op0
, t
);
4149 TREE_OPERAND (stmt
, 1) = t
;
4154 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
4155 ABS_EXPR. If the operand is <= 0, then simplify the
4156 ABS_EXPR into a NEGATE_EXPR. */
4159 simplify_abs_using_ranges (tree stmt
, tree rhs
)
4162 tree op
= TREE_OPERAND (rhs
, 0);
4163 tree type
= TREE_TYPE (op
);
4164 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
4166 if (TYPE_UNSIGNED (type
))
4168 val
= integer_zero_node
;
4172 val
= compare_range_with_value (LE_EXPR
, vr
, integer_zero_node
);
4175 val
= compare_range_with_value (GE_EXPR
, vr
, integer_zero_node
);
4179 if (integer_zerop (val
))
4180 val
= integer_one_node
;
4181 else if (integer_onep (val
))
4182 val
= integer_zero_node
;
4187 && (integer_onep (val
) || integer_zerop (val
)))
4191 if (integer_onep (val
))
4192 t
= build1 (NEGATE_EXPR
, TREE_TYPE (op
), op
);
4196 TREE_OPERAND (stmt
, 1) = t
;
4202 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
4203 a known value range VR.
4205 If there is one and only one value which will satisfy the
4206 conditional, then return that value. Else return NULL. */
4209 test_for_singularity (enum tree_code cond_code
, tree op0
,
4210 tree op1
, value_range_t
*vr
)
4215 /* Extract minimum/maximum values which satisfy the
4216 the conditional as it was written. */
4217 if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
4219 min
= TYPE_MIN_VALUE (TREE_TYPE (op0
));
4222 if (cond_code
== LT_EXPR
)
4224 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
4225 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (op0
), max
, one
);
4228 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
4230 max
= TYPE_MAX_VALUE (TREE_TYPE (op0
));
4233 if (cond_code
== GT_EXPR
)
4235 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
4236 min
= fold_build2 (PLUS_EXPR
, TREE_TYPE (op0
), min
, one
);
4240 /* Now refine the minimum and maximum values using any
4241 value range information we have for op0. */
4244 if (compare_values (vr
->min
, min
) == -1)
4248 if (compare_values (vr
->max
, max
) == 1)
4253 /* If the new min/max values have converged to a single value,
4254 then there is only one value which can satisfy the condition,
4255 return that value. */
4256 if (operand_equal_p (min
, max
, 0) && is_gimple_min_invariant (min
))
4262 /* Simplify a conditional using a relational operator to an equality
4263 test if the range information indicates only one value can satisfy
4264 the original conditional. */
4267 simplify_cond_using_ranges (tree stmt
)
4269 tree cond
= COND_EXPR_COND (stmt
);
4270 tree op0
= TREE_OPERAND (cond
, 0);
4271 tree op1
= TREE_OPERAND (cond
, 1);
4272 enum tree_code cond_code
= TREE_CODE (cond
);
4274 if (cond_code
!= NE_EXPR
4275 && cond_code
!= EQ_EXPR
4276 && TREE_CODE (op0
) == SSA_NAME
4277 && INTEGRAL_TYPE_P (TREE_TYPE (op0
))
4278 && is_gimple_min_invariant (op1
))
4280 value_range_t
*vr
= get_value_range (op0
);
4282 /* If we have range information for OP0, then we might be
4283 able to simplify this conditional. */
4284 if (vr
->type
== VR_RANGE
)
4286 tree
new = test_for_singularity (cond_code
, op0
, op1
, vr
);
4292 fprintf (dump_file
, "Simplified relational ");
4293 print_generic_expr (dump_file
, cond
, 0);
4294 fprintf (dump_file
, " into ");
4297 COND_EXPR_COND (stmt
)
4298 = build2 (EQ_EXPR
, boolean_type_node
, op0
, new);
4303 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
4304 fprintf (dump_file
, "\n");
4310 /* Try again after inverting the condition. We only deal
4311 with integral types here, so no need to worry about
4312 issues with inverting FP comparisons. */
4313 cond_code
= invert_tree_comparison (cond_code
, false);
4314 new = test_for_singularity (cond_code
, op0
, op1
, vr
);
4320 fprintf (dump_file
, "Simplified relational ");
4321 print_generic_expr (dump_file
, cond
, 0);
4322 fprintf (dump_file
, " into ");
4325 COND_EXPR_COND (stmt
)
4326 = build2 (NE_EXPR
, boolean_type_node
, op0
, new);
4331 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
4332 fprintf (dump_file
, "\n");
4341 /* Simplify STMT using ranges if possible. */
4344 simplify_stmt_using_ranges (tree stmt
)
4346 if (TREE_CODE (stmt
) == MODIFY_EXPR
)
4348 tree rhs
= TREE_OPERAND (stmt
, 1);
4349 enum tree_code rhs_code
= TREE_CODE (rhs
);
4351 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
4352 and BIT_AND_EXPR respectively if the first operand is greater
4353 than zero and the second operand is an exact power of two. */
4354 if ((rhs_code
== TRUNC_DIV_EXPR
|| rhs_code
== TRUNC_MOD_EXPR
)
4355 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0)))
4356 && integer_pow2p (TREE_OPERAND (rhs
, 1)))
4357 simplify_div_or_mod_using_ranges (stmt
, rhs
, rhs_code
);
4359 /* Transform ABS (X) into X or -X as appropriate. */
4360 if (rhs_code
== ABS_EXPR
4361 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == SSA_NAME
4362 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0))))
4363 simplify_abs_using_ranges (stmt
, rhs
);
4365 else if (TREE_CODE (stmt
) == COND_EXPR
4366 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt
)))
4368 simplify_cond_using_ranges (stmt
);
4372 /* Stack of dest,src equivalency pairs that need to be restored after
4373 each attempt to thread a block's incoming edge to an outgoing edge.
4375 A NULL entry is used to mark the end of pairs which need to be
4377 static VEC(tree
,heap
) *stack
;
4379 /* A trivial wrapper so that we can present the generic jump
4380 threading code with a simple API for simplifying statements. */
4382 simplify_stmt_for_jump_threading (tree stmt
)
4384 /* We only use VRP information to simplify conditionals. This is
4385 overly conservative, but it's unclear if doing more would be
4386 worth the compile time cost. */
4387 if (TREE_CODE (stmt
) != COND_EXPR
)
4390 return vrp_evaluate_conditional (COND_EXPR_COND (stmt
), true);
4393 /* Blocks which have more than one predecessor and more than
4394 one successor present jump threading opportunities. ie,
4395 when the block is reached from a specific predecessor, we
4396 may be able to determine which of the outgoing edges will
4397 be traversed. When this optimization applies, we are able
4398 to avoid conditionals at runtime and we may expose secondary
4399 optimization opportunities.
4401 This routine is effectively a driver for the generic jump
4402 threading code. It basically just presents the generic code
4403 with edges that may be suitable for jump threading.
4405 Unlike DOM, we do not iterate VRP if jump threading was successful.
4406 While iterating may expose new opportunities for VRP, it is expected
4407 those opportunities would be very limited and the compile time cost
4408 to expose those opportunities would be significant.
4410 As jump threading opportunities are discovered, they are registered
4411 for later realization. */
4414 identify_jump_threads (void)
4419 /* Ugh. When substituting values earlier in this pass we can
4420 wipe the dominance information. So rebuild the dominator
4421 information as we need it within the jump threading code. */
4422 calculate_dominance_info (CDI_DOMINATORS
);
4424 /* We do not allow VRP information to be used for jump threading
4425 across a back edge in the CFG. Otherwise it becomes too
4426 difficult to avoid eliminating loop exit tests. Of course
4427 EDGE_DFS_BACK is not accurate at this time so we have to
4429 mark_dfs_back_edges ();
4431 /* Allocate our unwinder stack to unwind any temporary equivalences
4432 that might be recorded. */
4433 stack
= VEC_alloc (tree
, heap
, 20);
4435 /* To avoid lots of silly node creation, we create a single
4436 conditional and just modify it in-place when attempting to
4438 dummy
= build2 (EQ_EXPR
, boolean_type_node
, NULL
, NULL
);
4439 dummy
= build3 (COND_EXPR
, void_type_node
, dummy
, NULL
, NULL
);
4441 /* Walk through all the blocks finding those which present a
4442 potential jump threading opportunity. We could set this up
4443 as a dominator walker and record data during the walk, but
4444 I doubt it's worth the effort for the classes of jump
4445 threading opportunities we are trying to identify at this
4446 point in compilation. */
4451 /* If the generic jump threading code does not find this block
4452 interesting, then there is nothing to do. */
4453 if (! potentially_threadable_block (bb
))
4456 /* We only care about blocks ending in a COND_EXPR. While there
4457 may be some value in handling SWITCH_EXPR here, I doubt it's
4458 terribly important. */
4459 last
= bsi_stmt (bsi_last (bb
));
4460 if (TREE_CODE (last
) != COND_EXPR
)
4463 /* We're basically looking for any kind of conditional with
4464 integral type arguments. */
4465 cond
= COND_EXPR_COND (last
);
4466 if ((TREE_CODE (cond
) == SSA_NAME
4467 && INTEGRAL_TYPE_P (TREE_TYPE (cond
)))
4468 || (COMPARISON_CLASS_P (cond
)
4469 && TREE_CODE (TREE_OPERAND (cond
, 0)) == SSA_NAME
4470 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond
, 0)))
4471 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == SSA_NAME
4472 || is_gimple_min_invariant (TREE_OPERAND (cond
, 1)))
4473 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond
, 1)))))
4478 /* We've got a block with multiple predecessors and multiple
4479 successors which also ends in a suitable conditional. For
4480 each predecessor, see if we can thread it to a specific
4482 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
4484 /* Do not thread across back edges or abnormal edges
4486 if (e
->flags
& (EDGE_DFS_BACK
| EDGE_COMPLEX
))
4489 thread_across_edge (dummy
, e
, true,
4491 simplify_stmt_for_jump_threading
);
4496 /* We do not actually update the CFG or SSA graphs at this point as
4497 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
4498 handle ASSERT_EXPRs gracefully. */
4501 /* We identified all the jump threading opportunities earlier, but could
4502 not transform the CFG at that time. This routine transforms the
4503 CFG and arranges for the dominator tree to be rebuilt if necessary.
4505 Note the SSA graph update will occur during the normal TODO
4506 processing by the pass manager. */
4508 finalize_jump_threads (void)
4510 bool cfg_altered
= false;
4511 cfg_altered
= thread_through_all_blocks ();
4513 /* If we threaded jumps, then we need to recompute the dominance
4514 information, to safely do that we must clean up the CFG first. */
4517 free_dominance_info (CDI_DOMINATORS
);
4518 cleanup_tree_cfg ();
4519 calculate_dominance_info (CDI_DOMINATORS
);
4521 VEC_free (tree
, heap
, stack
);
4525 /* Traverse all the blocks folding conditionals with known ranges. */
4531 prop_value_t
*single_val_range
;
4532 bool do_value_subst_p
;
4536 fprintf (dump_file
, "\nValue ranges after VRP:\n\n");
4537 dump_all_value_ranges (dump_file
);
4538 fprintf (dump_file
, "\n");
4541 /* We may have ended with ranges that have exactly one value. Those
4542 values can be substituted as any other copy/const propagated
4543 value using substitute_and_fold. */
4544 single_val_range
= XNEWVEC (prop_value_t
, num_ssa_names
);
4545 memset (single_val_range
, 0, num_ssa_names
* sizeof (*single_val_range
));
4547 do_value_subst_p
= false;
4548 for (i
= 0; i
< num_ssa_names
; i
++)
4550 && vr_value
[i
]->type
== VR_RANGE
4551 && vr_value
[i
]->min
== vr_value
[i
]->max
)
4553 single_val_range
[i
].value
= vr_value
[i
]->min
;
4554 do_value_subst_p
= true;
4557 if (!do_value_subst_p
)
4559 /* We found no single-valued ranges, don't waste time trying to
4560 do single value substitution in substitute_and_fold. */
4561 free (single_val_range
);
4562 single_val_range
= NULL
;
4565 substitute_and_fold (single_val_range
, true);
4567 /* We must identify jump threading opportunities before we release
4568 the datastructures built by VRP. */
4569 identify_jump_threads ();
4571 /* Free allocated memory. */
4572 for (i
= 0; i
< num_ssa_names
; i
++)
4575 BITMAP_FREE (vr_value
[i
]->equiv
);
4579 free (single_val_range
);
4582 /* So that we can distinguish between VRP data being available
4583 and not available. */
4588 /* Main entry point to VRP (Value Range Propagation). This pass is
4589 loosely based on J. R. C. Patterson, ``Accurate Static Branch
4590 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
4591 Programming Language Design and Implementation, pp. 67-78, 1995.
4592 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
4594 This is essentially an SSA-CCP pass modified to deal with ranges
4595 instead of constants.
4597 While propagating ranges, we may find that two or more SSA name
4598 have equivalent, though distinct ranges. For instance,
4601 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
4603 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
4607 In the code above, pointer p_5 has range [q_2, q_2], but from the
4608 code we can also determine that p_5 cannot be NULL and, if q_2 had
4609 a non-varying range, p_5's range should also be compatible with it.
4611 These equivalences are created by two expressions: ASSERT_EXPR and
4612 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
4613 result of another assertion, then we can use the fact that p_5 and
4614 p_4 are equivalent when evaluating p_5's range.
4616 Together with value ranges, we also propagate these equivalences
4617 between names so that we can take advantage of information from
4618 multiple ranges when doing final replacement. Note that this
4619 equivalency relation is transitive but not symmetric.
4621 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
4622 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
4623 in contexts where that assertion does not hold (e.g., in line 6).
4625 TODO, the main difference between this pass and Patterson's is that
4626 we do not propagate edge probabilities. We only compute whether
4627 edges can be taken or not. That is, instead of having a spectrum
4628 of jump probabilities between 0 and 1, we only deal with 0, 1 and
4629 DON'T KNOW. In the future, it may be worthwhile to propagate
4630 probabilities to aid branch prediction. */
4635 insert_range_assertions ();
4637 current_loops
= loop_optimizer_init (LOOPS_NORMAL
);
4639 scev_initialize (current_loops
);
4642 ssa_propagate (vrp_visit_stmt
, vrp_visit_phi_node
);
4648 loop_optimizer_finalize (current_loops
);
4649 current_loops
= NULL
;
4652 /* ASSERT_EXPRs must be removed before finalizing jump threads
4653 as finalizing jump threads calls the CFG cleanup code which
4654 does not properly handle ASSERT_EXPRs. */
4655 remove_range_assertions ();
4657 /* If we exposed any new variables, go ahead and put them into
4658 SSA form now, before we handle jump threading. This simplifies
4659 interactions between rewriting of _DECL nodes into SSA form
4660 and rewriting SSA_NAME nodes into SSA form after block
4661 duplication and CFG manipulation. */
4662 update_ssa (TODO_update_ssa
);
4664 finalize_jump_threads ();
4671 return flag_tree_vrp
!= 0;
4674 struct tree_opt_pass pass_vrp
=
4677 gate_vrp
, /* gate */
4678 execute_vrp
, /* execute */
4681 0, /* static_pass_number */
4682 TV_TREE_VRP
, /* tv_id */
4683 PROP_ssa
| PROP_alias
, /* properties_required */
4684 0, /* properties_provided */
4685 PROP_smt_usage
, /* properties_destroyed */
4686 0, /* todo_flags_start */
4692 | TODO_update_smt_usage
, /* todo_flags_finish */