1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
24 #include "coretypes.h"
29 #include "basic-block.h"
30 #include "tree-flow.h"
31 #include "tree-pass.h"
32 #include "tree-dump.h"
34 #include "diagnostic.h"
36 #include "tree-scalar-evolution.h"
37 #include "tree-ssa-propagate.h"
38 #include "tree-chrec.h"
40 /* Set of SSA names found during the dominator traversal of a
41 sub-graph in find_assert_locations. */
42 static sbitmap found_in_subgraph
;
44 /* Loop structure of the program. Used to analyze scalar evolutions
45 inside adjust_range_with_scev. */
46 static struct loops
*cfg_loops
;
48 /* Local functions. */
49 static int compare_values (tree val1
, tree val2
);
51 /* Location information for ASSERT_EXPRs. Each instance of this
52 structure describes an ASSERT_EXPR for an SSA name. Since a single
53 SSA name may have more than one assertion associated with it, these
54 locations are kept in a linked list attached to the corresponding
58 /* Basic block where the assertion would be inserted. */
61 /* Some assertions need to be inserted on an edge (e.g., assertions
62 generated by COND_EXPRs). In those cases, BB will be NULL. */
65 /* Pointer to the statement that generated this assertion. */
66 block_stmt_iterator si
;
68 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
69 enum tree_code comp_code
;
71 /* Value being compared against. */
74 /* Next node in the linked list. */
75 struct assert_locus_d
*next
;
78 typedef struct assert_locus_d
*assert_locus_t
;
80 /* If bit I is present, it means that SSA name N_i has a list of
81 assertions that should be inserted in the IL. */
82 static bitmap need_assert_for
;
84 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
85 holds a list of ASSERT_LOCUS_T nodes that describe where
86 ASSERT_EXPRs for SSA name N_I should be inserted. */
87 static assert_locus_t
*asserts_for
;
89 /* Set of blocks visited in find_assert_locations. Used to avoid
90 visiting the same block more than once. */
91 static sbitmap blocks_visited
;
93 /* Value range array. After propagation, VR_VALUE[I] holds the range
94 of values that SSA name N_I may take. */
95 static value_range_t
**vr_value
;
98 /* Return true if EXPR computes a non-zero value. */
101 expr_computes_nonzero (tree expr
)
103 /* Type casts won't change anything, so just strip them. */
106 /* Calling alloca, guarantees that the value is non-NULL. */
107 if (alloca_call_p (expr
))
110 /* The address of a non-weak symbol is never NULL, unless the user
111 has requested not to remove NULL pointer checks. */
112 if (flag_delete_null_pointer_checks
113 && TREE_CODE (expr
) == ADDR_EXPR
114 && DECL_P (TREE_OPERAND (expr
, 0))
115 && !DECL_WEAK (TREE_OPERAND (expr
, 0)))
118 /* IOR of any value with a nonzero value will result in a nonzero
120 if (TREE_CODE (expr
) == BIT_IOR_EXPR
121 && integer_nonzerop (TREE_OPERAND (expr
, 1)))
128 /* Return true if ARG is marked with the nonnull attribute in the
129 current function signature. */
132 nonnull_arg_p (tree arg
)
134 tree t
, attrs
, fntype
;
135 unsigned HOST_WIDE_INT arg_num
;
137 gcc_assert (TREE_CODE (arg
) == PARM_DECL
&& POINTER_TYPE_P (TREE_TYPE (arg
)));
139 fntype
= TREE_TYPE (current_function_decl
);
140 attrs
= lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype
));
142 /* If "nonnull" wasn't specified, we know nothing about the argument. */
143 if (attrs
== NULL_TREE
)
146 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
147 if (TREE_VALUE (attrs
) == NULL_TREE
)
150 /* Get the position number for ARG in the function signature. */
151 for (arg_num
= 1, t
= DECL_ARGUMENTS (current_function_decl
);
153 t
= TREE_CHAIN (t
), arg_num
++)
159 gcc_assert (t
== arg
);
161 /* Now see if ARG_NUM is mentioned in the nonnull list. */
162 for (t
= TREE_VALUE (attrs
); t
; t
= TREE_CHAIN (t
))
164 if (compare_tree_int (TREE_VALUE (t
), arg_num
) == 0)
172 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
175 set_value_range (value_range_t
*vr
, enum value_range_type t
, tree min
,
176 tree max
, bitmap equiv
)
178 #if defined ENABLE_CHECKING
179 /* Check the validity of the range. */
180 if (t
== VR_RANGE
|| t
== VR_ANTI_RANGE
)
184 gcc_assert (min
&& max
);
186 if (INTEGRAL_TYPE_P (TREE_TYPE (min
)) && t
== VR_ANTI_RANGE
)
187 gcc_assert (min
!= TYPE_MIN_VALUE (TREE_TYPE (min
))
188 || max
!= TYPE_MAX_VALUE (TREE_TYPE (max
)));
190 cmp
= compare_values (min
, max
);
191 gcc_assert (cmp
== 0 || cmp
== -1 || cmp
== -2);
194 if (t
== VR_UNDEFINED
|| t
== VR_VARYING
)
195 gcc_assert (min
== NULL_TREE
&& max
== NULL_TREE
);
197 if (t
== VR_UNDEFINED
|| t
== VR_VARYING
)
198 gcc_assert (equiv
== NULL
|| bitmap_empty_p (equiv
));
205 /* Since updating the equivalence set involves deep copying the
206 bitmaps, only do it if absolutely necessary. */
207 if (vr
->equiv
== NULL
)
208 vr
->equiv
= BITMAP_ALLOC (NULL
);
210 if (equiv
!= vr
->equiv
)
212 if (equiv
&& !bitmap_empty_p (equiv
))
213 bitmap_copy (vr
->equiv
, equiv
);
215 bitmap_clear (vr
->equiv
);
220 /* Copy value range FROM into value range TO. */
223 copy_value_range (value_range_t
*to
, value_range_t
*from
)
225 set_value_range (to
, from
->type
, from
->min
, from
->max
, from
->equiv
);
229 /* Set value range VR to a non-NULL range of type TYPE. */
232 set_value_range_to_nonnull (value_range_t
*vr
, tree type
)
234 tree zero
= build_int_cst (type
, 0);
235 set_value_range (vr
, VR_ANTI_RANGE
, zero
, zero
, vr
->equiv
);
239 /* Set value range VR to a NULL range of type TYPE. */
242 set_value_range_to_null (value_range_t
*vr
, tree type
)
244 tree zero
= build_int_cst (type
, 0);
245 set_value_range (vr
, VR_RANGE
, zero
, zero
, vr
->equiv
);
249 /* Set value range VR to VR_VARYING. */
252 set_value_range_to_varying (value_range_t
*vr
)
254 vr
->type
= VR_VARYING
;
255 vr
->min
= vr
->max
= NULL_TREE
;
257 bitmap_clear (vr
->equiv
);
261 /* Set value range VR to VR_UNDEFINED. */
264 set_value_range_to_undefined (value_range_t
*vr
)
266 vr
->type
= VR_UNDEFINED
;
267 vr
->min
= vr
->max
= NULL_TREE
;
269 bitmap_clear (vr
->equiv
);
273 /* Return value range information for VAR. Create an empty range
276 static value_range_t
*
277 get_value_range (tree var
)
281 unsigned ver
= SSA_NAME_VERSION (var
);
287 /* Create a default value range. */
288 vr_value
[ver
] = vr
= xmalloc (sizeof (*vr
));
289 memset (vr
, 0, sizeof (*vr
));
291 /* Allocate an equivalence set. */
292 vr
->equiv
= BITMAP_ALLOC (NULL
);
294 /* If VAR is a default definition, the variable can take any value
296 sym
= SSA_NAME_VAR (var
);
297 if (var
== var_ann (sym
)->default_def
)
299 /* Try to use the "nonnull" attribute to create ~[0, 0]
300 anti-ranges for pointers. Note that this is only valid with
301 default definitions of PARM_DECLs. */
302 if (TREE_CODE (sym
) == PARM_DECL
303 && POINTER_TYPE_P (TREE_TYPE (sym
))
304 && nonnull_arg_p (sym
))
305 set_value_range_to_nonnull (vr
, TREE_TYPE (sym
));
307 set_value_range_to_varying (vr
);
314 /* Update the value range and equivalence set for variable VAR to
315 NEW_VR. Return true if NEW_VR is different from VAR's previous
318 NOTE: This function assumes that NEW_VR is a temporary value range
319 object created for the sole purpose of updating VAR's range. The
320 storage used by the equivalence set from NEW_VR will be freed by
321 this function. Do not call update_value_range when NEW_VR
322 is the range object associated with another SSA name. */
325 update_value_range (tree var
, value_range_t
*new_vr
)
327 value_range_t
*old_vr
;
330 /* Update the value range, if necessary. */
331 old_vr
= get_value_range (var
);
332 is_new
= old_vr
->type
!= new_vr
->type
333 || old_vr
->min
!= new_vr
->min
334 || old_vr
->max
!= new_vr
->max
335 || (old_vr
->equiv
== NULL
&& new_vr
->equiv
)
336 || (old_vr
->equiv
&& new_vr
->equiv
== NULL
)
337 || (!bitmap_equal_p (old_vr
->equiv
, new_vr
->equiv
));
340 set_value_range (old_vr
, new_vr
->type
, new_vr
->min
, new_vr
->max
,
343 BITMAP_FREE (new_vr
->equiv
);
344 new_vr
->equiv
= NULL
;
350 /* Add VAR and VAR's equivalence set to EQUIV. */
353 add_equivalence (bitmap equiv
, tree var
)
355 unsigned ver
= SSA_NAME_VERSION (var
);
356 value_range_t
*vr
= vr_value
[ver
];
358 bitmap_set_bit (equiv
, ver
);
360 bitmap_ior_into (equiv
, vr
->equiv
);
364 /* Return true if VR is ~[0, 0]. */
367 range_is_nonnull (value_range_t
*vr
)
369 return vr
->type
== VR_ANTI_RANGE
370 && integer_zerop (vr
->min
)
371 && integer_zerop (vr
->max
);
375 /* Return true if VR is [0, 0]. */
378 range_is_null (value_range_t
*vr
)
380 return vr
->type
== VR_RANGE
381 && integer_zerop (vr
->min
)
382 && integer_zerop (vr
->max
);
386 /* Return true if value range VR involves at least one symbol. */
389 symbolic_range_p (value_range_t
*vr
)
391 return (!is_gimple_min_invariant (vr
->min
)
392 || !is_gimple_min_invariant (vr
->max
));
396 /* Like expr_computes_nonzero, but this function uses value ranges
400 vrp_expr_computes_nonzero (tree expr
)
402 if (expr_computes_nonzero (expr
))
405 /* If we have an expression of the form &X->a, then the expression
406 is nonnull if X is nonnull. */
407 if (TREE_CODE (expr
) == ADDR_EXPR
)
409 tree base
= get_base_address (TREE_OPERAND (expr
, 0));
411 if (base
!= NULL_TREE
412 && TREE_CODE (base
) == INDIRECT_REF
413 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
415 value_range_t
*vr
= get_value_range (TREE_OPERAND (base
, 0));
416 if (range_is_nonnull (vr
))
425 /* Compare two values VAL1 and VAL2. Return
427 -2 if VAL1 and VAL2 cannot be compared at compile-time,
430 +1 if VAL1 > VAL2, and
433 This is similar to tree_int_cst_compare but supports pointer values
434 and values that cannot be compared at compile time. */
437 compare_values (tree val1
, tree val2
)
442 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
444 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1
))
445 == POINTER_TYPE_P (TREE_TYPE (val2
)));
447 /* Do some limited symbolic comparisons. */
448 if (!POINTER_TYPE_P (TREE_TYPE (val1
)))
450 /* We can determine some comparisons against +INF and -INF even
451 if the other value is an expression. */
452 if (val1
== TYPE_MAX_VALUE (TREE_TYPE (val1
))
453 && TREE_CODE (val2
) == MINUS_EXPR
)
455 /* +INF > NAME - CST. */
458 else if (val1
== TYPE_MIN_VALUE (TREE_TYPE (val1
))
459 && TREE_CODE (val2
) == PLUS_EXPR
)
461 /* -INF < NAME + CST. */
464 else if (TREE_CODE (val1
) == MINUS_EXPR
465 && val2
== TYPE_MAX_VALUE (TREE_TYPE (val2
)))
467 /* NAME - CST < +INF. */
470 else if (TREE_CODE (val1
) == PLUS_EXPR
471 && val2
== TYPE_MIN_VALUE (TREE_TYPE (val2
)))
473 /* NAME + CST > -INF. */
478 if ((TREE_CODE (val1
) == SSA_NAME
479 || TREE_CODE (val1
) == PLUS_EXPR
480 || TREE_CODE (val1
) == MINUS_EXPR
)
481 && (TREE_CODE (val2
) == SSA_NAME
482 || TREE_CODE (val2
) == PLUS_EXPR
483 || TREE_CODE (val2
) == MINUS_EXPR
))
487 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
488 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
489 same name, return -2. */
490 if (TREE_CODE (val1
) == SSA_NAME
)
497 n1
= TREE_OPERAND (val1
, 0);
498 c1
= TREE_OPERAND (val1
, 1);
501 if (TREE_CODE (val2
) == SSA_NAME
)
508 n2
= TREE_OPERAND (val2
, 0);
509 c2
= TREE_OPERAND (val2
, 1);
512 /* Both values must use the same name. */
516 if (TREE_CODE (val1
) == SSA_NAME
)
518 if (TREE_CODE (val2
) == SSA_NAME
)
521 else if (TREE_CODE (val2
) == PLUS_EXPR
)
522 /* NAME < NAME + CST */
524 else if (TREE_CODE (val2
) == MINUS_EXPR
)
525 /* NAME > NAME - CST */
528 else if (TREE_CODE (val1
) == PLUS_EXPR
)
530 if (TREE_CODE (val2
) == SSA_NAME
)
531 /* NAME + CST > NAME */
533 else if (TREE_CODE (val2
) == PLUS_EXPR
)
534 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
535 return compare_values (c1
, c2
);
536 else if (TREE_CODE (val2
) == MINUS_EXPR
)
537 /* NAME + CST1 > NAME - CST2 */
540 else if (TREE_CODE (val1
) == MINUS_EXPR
)
542 if (TREE_CODE (val2
) == SSA_NAME
)
543 /* NAME - CST < NAME */
545 else if (TREE_CODE (val2
) == PLUS_EXPR
)
546 /* NAME - CST1 < NAME + CST2 */
548 else if (TREE_CODE (val2
) == MINUS_EXPR
)
549 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
550 C1 and C2 are swapped in the call to compare_values. */
551 return compare_values (c2
, c1
);
557 /* We cannot compare non-constants. */
558 if (!is_gimple_min_invariant (val1
) || !is_gimple_min_invariant (val2
))
561 /* We cannot compare overflowed values. */
562 if (TREE_OVERFLOW (val1
) || TREE_OVERFLOW (val2
))
565 if (!POINTER_TYPE_P (TREE_TYPE (val1
)))
566 return tree_int_cst_compare (val1
, val2
);
571 /* First see if VAL1 and VAL2 are not the same. */
572 if (val1
== val2
|| operand_equal_p (val1
, val2
, 0))
575 /* If VAL1 is a lower address than VAL2, return -1. */
576 t
= fold_binary (LT_EXPR
, boolean_type_node
, val1
, val2
);
577 if (t
== boolean_true_node
)
580 /* If VAL1 is a higher address than VAL2, return +1. */
581 t
= fold_binary (GT_EXPR
, boolean_type_node
, val1
, val2
);
582 if (t
== boolean_true_node
)
585 /* If VAL1 is different than VAL2, return +2. */
586 t
= fold_binary (NE_EXPR
, boolean_type_node
, val1
, val2
);
587 if (t
== boolean_true_node
)
595 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
596 0 if VAL is not inside VR,
597 -2 if we cannot tell either way. */
600 value_inside_range (tree val
, value_range_t
*vr
)
604 cmp1
= compare_values (val
, vr
->min
);
605 if (cmp1
== -2 || cmp1
== 2)
608 cmp2
= compare_values (val
, vr
->max
);
609 if (cmp2
== -2 || cmp2
== 2)
612 return (cmp1
== 0 || cmp1
== 1) && (cmp2
== -1 || cmp2
== 0);
616 /* Return true if value ranges VR0 and VR1 have a non-empty
620 value_ranges_intersect_p (value_range_t
*vr0
, value_range_t
*vr1
)
622 return (value_inside_range (vr1
->min
, vr0
) == 1
623 || value_inside_range (vr1
->max
, vr0
) == 1
624 || value_inside_range (vr0
->min
, vr1
) == 1
625 || value_inside_range (vr0
->max
, vr1
) == 1);
629 /* Return true if VR includes the value zero, false otherwise. */
632 range_includes_zero_p (value_range_t
*vr
)
636 gcc_assert (vr
->type
!= VR_UNDEFINED
637 && vr
->type
!= VR_VARYING
638 && !symbolic_range_p (vr
));
640 zero
= build_int_cst (TREE_TYPE (vr
->min
), 0);
641 return (value_inside_range (zero
, vr
) == 1);
645 /* Extract value range information from an ASSERT_EXPR EXPR and store
649 extract_range_from_assert (value_range_t
*vr_p
, tree expr
)
651 tree var
, cond
, limit
, min
, max
, type
;
652 value_range_t
*var_vr
, *limit_vr
;
653 enum tree_code cond_code
;
655 var
= ASSERT_EXPR_VAR (expr
);
656 cond
= ASSERT_EXPR_COND (expr
);
658 gcc_assert (COMPARISON_CLASS_P (cond
));
660 /* Find VAR in the ASSERT_EXPR conditional. */
661 if (var
== TREE_OPERAND (cond
, 0))
663 /* If the predicate is of the form VAR COMP LIMIT, then we just
664 take LIMIT from the RHS and use the same comparison code. */
665 limit
= TREE_OPERAND (cond
, 1);
666 cond_code
= TREE_CODE (cond
);
670 /* If the predicate is of the form LIMIT COMP VAR, then we need
671 to flip around the comparison code to create the proper range
673 limit
= TREE_OPERAND (cond
, 0);
674 cond_code
= swap_tree_comparison (TREE_CODE (cond
));
677 type
= TREE_TYPE (limit
);
678 gcc_assert (limit
!= var
);
680 /* For pointer arithmetic, we only keep track of pointer equality
682 if (POINTER_TYPE_P (type
) && cond_code
!= NE_EXPR
&& cond_code
!= EQ_EXPR
)
684 set_value_range_to_varying (vr_p
);
688 /* If LIMIT is another SSA name and LIMIT has a range of its own,
689 try to use LIMIT's range to avoid creating symbolic ranges
691 limit_vr
= (TREE_CODE (limit
) == SSA_NAME
) ? get_value_range (limit
) : NULL
;
693 /* LIMIT's range is only interesting if it has any useful information. */
695 && (limit_vr
->type
== VR_UNDEFINED
696 || limit_vr
->type
== VR_VARYING
697 || symbolic_range_p (limit_vr
)))
700 /* Special handling for integral types with super-types. Some FEs
701 construct integral types derived from other types and restrict
702 the range of values these new types may take.
704 It may happen that LIMIT is actually smaller than TYPE's minimum
705 value. For instance, the Ada FE is generating code like this
708 D.1480_32 = nam_30 - 300000361;
709 if (D.1480_32 <= 1) goto <L112>; else goto <L52>;
711 D.1480_94 = ASSERT_EXPR <D.1480_32, D.1480_32 <= 1>;
713 All the names are of type types__name_id___XDLU_300000000__399999999
714 which has min == 300000000 and max == 399999999. This means that
715 the ASSERT_EXPR would try to create the range [3000000, 1] which
718 The fact that the type specifies MIN and MAX values does not
719 automatically mean that every variable of that type will always
720 be within that range, so the predicate may well be true at run
721 time. If we had symbolic -INF and +INF values, we could
722 represent this range, but we currently represent -INF and +INF
723 using the type's min and max values.
725 So, the only sensible thing we can do for now is set the
726 resulting range to VR_VARYING. TODO, would having symbolic -INF
727 and +INF values be worth the trouble? */
728 if (TREE_CODE (limit
) != SSA_NAME
729 && INTEGRAL_TYPE_P (type
)
732 if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
734 tree type_min
= TYPE_MIN_VALUE (type
);
735 int cmp
= compare_values (limit
, type_min
);
737 /* For < or <= comparisons, if LIMIT is smaller than
738 TYPE_MIN, set the range to VR_VARYING. */
739 if (cmp
== -1 || cmp
== 0)
741 set_value_range_to_varying (vr_p
);
745 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
747 tree type_max
= TYPE_MIN_VALUE (type
);
748 int cmp
= compare_values (limit
, type_max
);
750 /* For > or >= comparisons, if LIMIT is bigger than
751 TYPE_MAX, set the range to VR_VARYING. */
752 if (cmp
== 1 || cmp
== 0)
754 set_value_range_to_varying (vr_p
);
760 /* The new range has the same set of equivalences of VAR's range. */
761 gcc_assert (vr_p
->equiv
== NULL
);
762 vr_p
->equiv
= BITMAP_ALLOC (NULL
);
763 add_equivalence (vr_p
->equiv
, var
);
765 /* Extract a new range based on the asserted comparison for VAR and
766 LIMIT's value range. Notice that if LIMIT has an anti-range, we
767 will only use it for equality comparisons (EQ_EXPR). For any
768 other kind of assertion, we cannot derive a range from LIMIT's
769 anti-range that can be used to describe the new range. For
770 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
771 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
772 no single range for x_2 that could describe LE_EXPR, so we might
773 as well build the range [b_4, +INF] for it. */
774 if (cond_code
== EQ_EXPR
)
776 enum value_range_type range_type
;
780 range_type
= limit_vr
->type
;
786 range_type
= VR_RANGE
;
791 set_value_range (vr_p
, range_type
, min
, max
, vr_p
->equiv
);
793 /* When asserting the equality VAR == LIMIT and LIMIT is another
794 SSA name, the new range will also inherit the equivalence set
796 if (TREE_CODE (limit
) == SSA_NAME
)
797 add_equivalence (vr_p
->equiv
, limit
);
799 else if (cond_code
== NE_EXPR
)
801 /* As described above, when LIMIT's range is an anti-range and
802 this assertion is an inequality (NE_EXPR), then we cannot
803 derive anything from the anti-range. For instance, if
804 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
805 not imply that VAR's range is [0, 0]. So, in the case of
806 anti-ranges, we just assert the inequality using LIMIT and
807 not its anti-range. */
809 || limit_vr
->type
== VR_ANTI_RANGE
)
820 /* If MIN and MAX cover the whole range for their type, then
821 just use the original LIMIT. */
822 if (INTEGRAL_TYPE_P (type
)
823 && min
== TYPE_MIN_VALUE (type
)
824 && max
== TYPE_MAX_VALUE (type
))
827 set_value_range (vr_p
, VR_ANTI_RANGE
, min
, max
, vr_p
->equiv
);
829 else if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
831 min
= TYPE_MIN_VALUE (type
);
833 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
837 /* If LIMIT_VR is of the form [N1, N2], we need to build the
838 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
843 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
844 if (cond_code
== LT_EXPR
)
846 tree one
= build_int_cst (type
, 1);
847 max
= fold (build (MINUS_EXPR
, type
, max
, one
));
850 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
852 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
854 max
= TYPE_MAX_VALUE (type
);
856 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
860 /* If LIMIT_VR is of the form [N1, N2], we need to build the
861 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
866 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
867 if (cond_code
== GT_EXPR
)
869 tree one
= build_int_cst (type
, 1);
870 min
= fold (build (PLUS_EXPR
, type
, min
, one
));
873 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
878 /* If VAR already had a known range and the two ranges have a
879 non-empty intersection, we can refine the resulting range.
880 Since the assert expression creates an equivalency and at the
881 same time it asserts a predicate, we can take the intersection of
882 the two ranges to get better precision. */
883 var_vr
= get_value_range (var
);
884 if (var_vr
->type
== VR_RANGE
885 && vr_p
->type
== VR_RANGE
886 && value_ranges_intersect_p (var_vr
, vr_p
))
888 /* Use the larger of the two minimums. */
889 if (compare_values (vr_p
->min
, var_vr
->min
) == -1)
894 /* Use the smaller of the two maximums. */
895 if (compare_values (vr_p
->max
, var_vr
->max
) == 1)
900 set_value_range (vr_p
, vr_p
->type
, min
, max
, vr_p
->equiv
);
905 /* Extract range information from SSA name VAR and store it in VR. If
906 VAR has an interesting range, use it. Otherwise, create the
907 range [VAR, VAR] and return it. This is useful in situations where
908 we may have conditionals testing values of VARYING names. For
915 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
919 extract_range_from_ssa_name (value_range_t
*vr
, tree var
)
921 value_range_t
*var_vr
= get_value_range (var
);
923 if (var_vr
->type
!= VR_UNDEFINED
&& var_vr
->type
!= VR_VARYING
)
924 copy_value_range (vr
, var_vr
);
926 set_value_range (vr
, VR_RANGE
, var
, var
, NULL
);
928 add_equivalence (vr
->equiv
, var
);
932 /* Wrapper around int_const_binop. If the operation overflows and we
933 are not using wrapping arithmetic, then adjust the result to be
934 -INF or +INF depending on CODE, VAL1 and VAL2. */
937 vrp_int_const_binop (enum tree_code code
, tree val1
, tree val2
)
942 return int_const_binop (code
, val1
, val2
, 0);
944 /* If we are not using wrapping arithmetic, operate symbolically
946 res
= int_const_binop (code
, val1
, val2
, 0);
948 /* If the operation overflowed but neither VAL1 nor VAL2 are
949 overflown, return -INF or +INF depending on the operation
950 and the combination of signs of the operands. */
951 if (TREE_OVERFLOW (res
)
952 && !TREE_OVERFLOW (val1
)
953 && !TREE_OVERFLOW (val2
))
955 int sgn1
= tree_int_cst_sgn (val1
);
956 int sgn2
= tree_int_cst_sgn (val2
);
958 /* Notice that we only need to handle the restricted set of
959 operations handled by extract_range_from_binary_expr.
960 Among them, only multiplication, addition and subtraction
961 can yield overflow without overflown operands because we
962 are working with integral types only... except in the
963 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
966 /* For multiplication, the sign of the overflow is given
967 by the comparison of the signs of the operands. */
968 if ((code
== MULT_EXPR
&& sgn1
== sgn2
)
969 /* For addition, the operands must be of the same sign
970 to yield an overflow. Its sign is therefore that
971 of one of the operands, for example the first. */
972 || (code
== PLUS_EXPR
&& sgn1
> 0)
973 /* For subtraction, the operands must be of different
974 signs to yield an overflow. Its sign is therefore
975 that of the first operand or the opposite of that
976 of the second operand. */
977 || (code
== MINUS_EXPR
&& sgn1
> 0)
978 /* For division, the only case is -INF / -1 = +INF. */
979 || code
== TRUNC_DIV_EXPR
980 || code
== FLOOR_DIV_EXPR
981 || code
== CEIL_DIV_EXPR
982 || code
== EXACT_DIV_EXPR
983 || code
== ROUND_DIV_EXPR
)
984 return TYPE_MAX_VALUE (TREE_TYPE (res
));
986 return TYPE_MIN_VALUE (TREE_TYPE (res
));
993 /* Extract range information from a binary expression EXPR based on
994 the ranges of each of its operands and the expression code. */
997 extract_range_from_binary_expr (value_range_t
*vr
, tree expr
)
999 enum tree_code code
= TREE_CODE (expr
);
1000 tree op0
, op1
, min
, max
;
1002 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1003 value_range_t vr1
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1005 /* Not all binary expressions can be applied to ranges in a
1006 meaningful way. Handle only arithmetic operations. */
1007 if (code
!= PLUS_EXPR
1008 && code
!= MINUS_EXPR
1009 && code
!= MULT_EXPR
1010 && code
!= TRUNC_DIV_EXPR
1011 && code
!= FLOOR_DIV_EXPR
1012 && code
!= CEIL_DIV_EXPR
1013 && code
!= EXACT_DIV_EXPR
1014 && code
!= ROUND_DIV_EXPR
1017 && code
!= TRUTH_ANDIF_EXPR
1018 && code
!= TRUTH_ORIF_EXPR
1019 && code
!= TRUTH_AND_EXPR
1020 && code
!= TRUTH_OR_EXPR
1021 && code
!= TRUTH_XOR_EXPR
)
1023 set_value_range_to_varying (vr
);
1027 /* Get value ranges for each operand. For constant operands, create
1028 a new value range with the operand to simplify processing. */
1029 op0
= TREE_OPERAND (expr
, 0);
1030 if (TREE_CODE (op0
) == SSA_NAME
)
1031 vr0
= *(get_value_range (op0
));
1032 else if (is_gimple_min_invariant (op0
))
1033 set_value_range (&vr0
, VR_RANGE
, op0
, op0
, NULL
);
1035 set_value_range_to_varying (&vr0
);
1037 op1
= TREE_OPERAND (expr
, 1);
1038 if (TREE_CODE (op1
) == SSA_NAME
)
1039 vr1
= *(get_value_range (op1
));
1040 else if (is_gimple_min_invariant (op1
))
1041 set_value_range (&vr1
, VR_RANGE
, op1
, op1
, NULL
);
1043 set_value_range_to_varying (&vr1
);
1045 /* If either range is UNDEFINED, so is the result. */
1046 if (vr0
.type
== VR_UNDEFINED
|| vr1
.type
== VR_UNDEFINED
)
1048 set_value_range_to_undefined (vr
);
1052 /* Refuse to operate on VARYING ranges, ranges of different kinds
1053 and symbolic ranges. TODO, we may be able to derive anti-ranges
1055 if (vr0
.type
== VR_VARYING
1056 || vr1
.type
== VR_VARYING
1057 || vr0
.type
!= vr1
.type
1058 || symbolic_range_p (&vr0
)
1059 || symbolic_range_p (&vr1
))
1061 set_value_range_to_varying (vr
);
1065 /* Now evaluate the expression to determine the new range. */
1066 if (POINTER_TYPE_P (TREE_TYPE (expr
))
1067 || POINTER_TYPE_P (TREE_TYPE (op0
))
1068 || POINTER_TYPE_P (TREE_TYPE (op1
)))
1070 /* For pointer types, we are really only interested in asserting
1071 whether the expression evaluates to non-NULL. FIXME, we used
1072 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1073 ivopts is generating expressions with pointer multiplication
1075 if (code
== PLUS_EXPR
)
1077 if (range_is_nonnull (&vr0
) || range_is_nonnull (&vr1
))
1078 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1079 else if (range_is_null (&vr0
) && range_is_null (&vr1
))
1080 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1082 set_value_range_to_varying (vr
);
1086 /* Subtracting from a pointer, may yield 0, so just drop the
1087 resulting range to varying. */
1088 set_value_range_to_varying (vr
);
1094 /* For integer ranges, apply the operation to each end of the
1095 range and see what we end up with. */
1096 if (code
== TRUTH_ANDIF_EXPR
1097 || code
== TRUTH_ORIF_EXPR
1098 || code
== TRUTH_AND_EXPR
1099 || code
== TRUTH_OR_EXPR
1100 || code
== TRUTH_XOR_EXPR
)
1102 /* Boolean expressions cannot be folded with int_const_binop. */
1103 min
= fold_binary (code
, TREE_TYPE (expr
), vr0
.min
, vr1
.min
);
1104 max
= fold_binary (code
, TREE_TYPE (expr
), vr0
.max
, vr1
.max
);
1106 else if (code
== PLUS_EXPR
1108 || code
== MAX_EXPR
)
1110 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1111 VR_VARYING. It would take more effort to compute a precise
1112 range for such a case. For example, if we have op0 == 1 and
1113 op1 == -1 with their ranges both being ~[0,0], we would have
1114 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1115 Note that we are guaranteed to have vr0.type == vr1.type at
1117 if (code
== PLUS_EXPR
&& vr0
.type
== VR_ANTI_RANGE
)
1119 set_value_range_to_varying (vr
);
1123 /* For operations that make the resulting range directly
1124 proportional to the original ranges, apply the operation to
1125 the same end of each range. */
1126 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1127 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.max
);
1129 else if (code
== MULT_EXPR
1130 || code
== TRUNC_DIV_EXPR
1131 || code
== FLOOR_DIV_EXPR
1132 || code
== CEIL_DIV_EXPR
1133 || code
== EXACT_DIV_EXPR
1134 || code
== ROUND_DIV_EXPR
)
1139 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1140 drop to VR_VARYING. It would take more effort to compute a
1141 precise range for such a case. For example, if we have
1142 op0 == 65536 and op1 == 65536 with their ranges both being
1143 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1144 we cannot claim that the product is in ~[0,0]. Note that we
1145 are guaranteed to have vr0.type == vr1.type at this
1147 if (code
== MULT_EXPR
1148 && vr0
.type
== VR_ANTI_RANGE
1149 && (flag_wrapv
|| TYPE_UNSIGNED (TREE_TYPE (op0
))))
1151 set_value_range_to_varying (vr
);
1155 /* Multiplications and divisions are a bit tricky to handle,
1156 depending on the mix of signs we have in the two ranges, we
1157 need to operate on different values to get the minimum and
1158 maximum values for the new range. One approach is to figure
1159 out all the variations of range combinations and do the
1162 However, this involves several calls to compare_values and it
1163 is pretty convoluted. It's simpler to do the 4 operations
1164 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1165 MAX1) and then figure the smallest and largest values to form
1168 /* Divisions by zero result in a VARYING value. */
1169 if (code
!= MULT_EXPR
&& range_includes_zero_p (&vr1
))
1171 set_value_range_to_varying (vr
);
1175 /* Compute the 4 cross operations. */
1176 val
[0] = vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1178 val
[1] = (vr1
.max
!= vr1
.min
)
1179 ? vrp_int_const_binop (code
, vr0
.min
, vr1
.max
)
1182 val
[2] = (vr0
.max
!= vr0
.min
)
1183 ? vrp_int_const_binop (code
, vr0
.max
, vr1
.min
)
1186 val
[3] = (vr0
.min
!= vr1
.min
&& vr0
.max
!= vr1
.max
)
1187 ? vrp_int_const_binop (code
, vr0
.max
, vr1
.max
)
1190 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1194 for (i
= 1; i
< 4; i
++)
1196 if (TREE_OVERFLOW (min
) || TREE_OVERFLOW (max
))
1201 if (TREE_OVERFLOW (val
[i
]))
1203 /* If we found an overflowed value, set MIN and MAX
1204 to it so that we set the resulting range to
1210 if (compare_values (val
[i
], min
) == -1)
1213 if (compare_values (val
[i
], max
) == 1)
1218 else if (code
== MINUS_EXPR
)
1220 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1221 VR_VARYING. It would take more effort to compute a precise
1222 range for such a case. For example, if we have op0 == 1 and
1223 op1 == 1 with their ranges both being ~[0,0], we would have
1224 op0 - op1 == 0, so we cannot claim that the difference is in
1225 ~[0,0]. Note that we are guaranteed to have
1226 vr0.type == vr1.type at this point. */
1227 if (vr0
.type
== VR_ANTI_RANGE
)
1229 set_value_range_to_varying (vr
);
1233 /* For MINUS_EXPR, apply the operation to the opposite ends of
1235 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.max
);
1236 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.min
);
1241 /* If either MIN or MAX overflowed, then set the resulting range to
1243 if (TREE_OVERFLOW (min
) || TREE_OVERFLOW (max
))
1245 set_value_range_to_varying (vr
);
1249 cmp
= compare_values (min
, max
);
1250 if (cmp
== -2 || cmp
== 1)
1252 /* If the new range has its limits swapped around (MIN > MAX),
1253 then the operation caused one of them to wrap around, mark
1254 the new range VARYING. */
1255 set_value_range_to_varying (vr
);
1258 set_value_range (vr
, vr0
.type
, min
, max
, NULL
);
1262 /* Extract range information from a unary expression EXPR based on
1263 the range of its operand and the expression code. */
1266 extract_range_from_unary_expr (value_range_t
*vr
, tree expr
)
1268 enum tree_code code
= TREE_CODE (expr
);
1271 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1273 /* Refuse to operate on certain unary expressions for which we
1274 cannot easily determine a resulting range. */
1275 if (code
== FIX_TRUNC_EXPR
1276 || code
== FIX_CEIL_EXPR
1277 || code
== FIX_FLOOR_EXPR
1278 || code
== FIX_ROUND_EXPR
1279 || code
== FLOAT_EXPR
1280 || code
== BIT_NOT_EXPR
1281 || code
== NON_LVALUE_EXPR
1282 || code
== CONJ_EXPR
)
1284 set_value_range_to_varying (vr
);
1288 /* Get value ranges for the operand. For constant operands, create
1289 a new value range with the operand to simplify processing. */
1290 op0
= TREE_OPERAND (expr
, 0);
1291 if (TREE_CODE (op0
) == SSA_NAME
)
1292 vr0
= *(get_value_range (op0
));
1293 else if (is_gimple_min_invariant (op0
))
1294 set_value_range (&vr0
, VR_RANGE
, op0
, op0
, NULL
);
1296 set_value_range_to_varying (&vr0
);
1298 /* If VR0 is UNDEFINED, so is the result. */
1299 if (vr0
.type
== VR_UNDEFINED
)
1301 set_value_range_to_undefined (vr
);
1305 /* Refuse to operate on varying and symbolic ranges. Also, if the
1306 operand is neither a pointer nor an integral type, set the
1307 resulting range to VARYING. TODO, in some cases we may be able
1308 to derive anti-ranges (like non-zero values). */
1309 if (vr0
.type
== VR_VARYING
1310 || (!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
1311 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
1312 || symbolic_range_p (&vr0
))
1314 set_value_range_to_varying (vr
);
1318 /* If the expression involves pointers, we are only interested in
1319 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
1320 if (POINTER_TYPE_P (TREE_TYPE (expr
)) || POINTER_TYPE_P (TREE_TYPE (op0
)))
1322 if (range_is_nonnull (&vr0
) || expr_computes_nonzero (expr
))
1323 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1324 else if (range_is_null (&vr0
))
1325 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1327 set_value_range_to_varying (vr
);
1332 /* Handle unary expressions on integer ranges. */
1333 if (code
== NOP_EXPR
|| code
== CONVERT_EXPR
)
1335 tree inner_type
= TREE_TYPE (op0
);
1336 tree outer_type
= TREE_TYPE (expr
);
1338 /* If VR0 represents a simple range, then try to convert
1339 the min and max values for the range to the same type
1340 as OUTER_TYPE. If the results compare equal to VR0's
1341 min and max values and the new min is still less than
1342 or equal to the new max, then we can safely use the newly
1343 computed range for EXPR. This allows us to compute
1344 accurate ranges through many casts. */
1345 if (vr0
.type
== VR_RANGE
)
1347 tree new_min
, new_max
;
1349 /* Convert VR0's min/max to OUTER_TYPE. */
1350 new_min
= fold_convert (outer_type
, vr0
.min
);
1351 new_max
= fold_convert (outer_type
, vr0
.max
);
1353 /* Verify the new min/max values are gimple values and
1354 that they compare equal to VR0's min/max values. */
1355 if (is_gimple_val (new_min
)
1356 && is_gimple_val (new_max
)
1357 && tree_int_cst_equal (new_min
, vr0
.min
)
1358 && tree_int_cst_equal (new_max
, vr0
.max
)
1359 && compare_values (new_min
, new_max
) <= 0
1360 && compare_values (new_min
, new_max
) >= -2)
1362 set_value_range (vr
, VR_RANGE
, new_min
, new_max
, vr
->equiv
);
1367 /* When converting types of different sizes, set the result to
1368 VARYING. Things like sign extensions and precision loss may
1369 change the range. For instance, if x_3 is of type 'long long
1370 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
1371 is impossible to know at compile time whether y_5 will be
1373 if (TYPE_SIZE (inner_type
) != TYPE_SIZE (outer_type
)
1374 || TYPE_PRECISION (inner_type
) != TYPE_PRECISION (outer_type
))
1376 set_value_range_to_varying (vr
);
1381 /* Apply the operation to each end of the range and see what we end
1383 if (code
== NEGATE_EXPR
1384 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
1386 /* Negating an anti-range doesn't really do anything to it. The
1387 new range will also not take on the same range of values
1388 excluded by the original anti-range. */
1389 if (vr0
.type
== VR_ANTI_RANGE
)
1391 copy_value_range (vr
, &vr0
);
1395 /* NEGATE_EXPR flips the range around. */
1396 min
= (vr0
.max
== TYPE_MAX_VALUE (TREE_TYPE (expr
)))
1397 ? TYPE_MIN_VALUE (TREE_TYPE (expr
))
1398 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1400 max
= (vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
)))
1401 ? TYPE_MAX_VALUE (TREE_TYPE (expr
))
1402 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1404 else if (code
== ABS_EXPR
1405 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
1407 /* ABS_EXPR may flip the range around, if the original range
1408 included negative values. */
1409 min
= (vr0
.min
== TYPE_MIN_VALUE (TREE_TYPE (expr
)))
1410 ? TYPE_MAX_VALUE (TREE_TYPE (expr
))
1411 : fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1413 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1415 /* If the range was reversed, swap MIN and MAX. */
1416 if (compare_values (min
, max
) == 1)
1425 /* Otherwise, operate on each end of the range. */
1426 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
1427 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
1430 cmp
= compare_values (min
, max
);
1431 if (cmp
== -2 || cmp
== 1)
1433 /* If the new range has its limits swapped around (MIN > MAX),
1434 then the operation caused one of them to wrap around, mark
1435 the new range VARYING. */
1436 set_value_range_to_varying (vr
);
1439 set_value_range (vr
, vr0
.type
, min
, max
, NULL
);
1443 /* Extract range information from a comparison expression EXPR based
1444 on the range of its operand and the expression code. */
1447 extract_range_from_comparison (value_range_t
*vr
, tree expr
)
1449 tree val
= vrp_evaluate_conditional (expr
, false);
1452 /* Since this expression was found on the RHS of an assignment,
1453 its type may be different from _Bool. Convert VAL to EXPR's
1455 val
= fold_convert (TREE_TYPE (expr
), val
);
1456 set_value_range (vr
, VR_RANGE
, val
, val
, vr
->equiv
);
1459 set_value_range_to_varying (vr
);
1463 /* Try to compute a useful range out of expression EXPR and store it
1467 extract_range_from_expr (value_range_t
*vr
, tree expr
)
1469 enum tree_code code
= TREE_CODE (expr
);
1471 if (code
== ASSERT_EXPR
)
1472 extract_range_from_assert (vr
, expr
);
1473 else if (code
== SSA_NAME
)
1474 extract_range_from_ssa_name (vr
, expr
);
1475 else if (TREE_CODE_CLASS (code
) == tcc_binary
1476 || code
== TRUTH_ANDIF_EXPR
1477 || code
== TRUTH_ORIF_EXPR
1478 || code
== TRUTH_AND_EXPR
1479 || code
== TRUTH_OR_EXPR
1480 || code
== TRUTH_XOR_EXPR
)
1481 extract_range_from_binary_expr (vr
, expr
);
1482 else if (TREE_CODE_CLASS (code
) == tcc_unary
)
1483 extract_range_from_unary_expr (vr
, expr
);
1484 else if (TREE_CODE_CLASS (code
) == tcc_comparison
)
1485 extract_range_from_comparison (vr
, expr
);
1486 else if (vrp_expr_computes_nonzero (expr
))
1487 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1488 else if (is_gimple_min_invariant (expr
))
1489 set_value_range (vr
, VR_RANGE
, expr
, expr
, NULL
);
1491 set_value_range_to_varying (vr
);
1494 /* Given a range VR, a LOOP and a variable VAR, determine whether it
1495 would be profitable to adjust VR using scalar evolution information
1496 for VAR. If so, update VR with the new limits. */
1499 adjust_range_with_scev (value_range_t
*vr
, struct loop
*loop
, tree stmt
,
1502 tree init
, step
, chrec
;
1505 /* TODO. Don't adjust anti-ranges. An anti-range may provide
1506 better opportunities than a regular range, but I'm not sure. */
1507 if (vr
->type
== VR_ANTI_RANGE
)
1510 chrec
= analyze_scalar_evolution (loop
, var
);
1511 if (TREE_CODE (chrec
) != POLYNOMIAL_CHREC
)
1514 init
= CHREC_LEFT (chrec
);
1515 step
= CHREC_RIGHT (chrec
);
1517 /* If STEP is symbolic, we can't know whether INIT will be the
1518 minimum or maximum value in the range. */
1519 if (!is_gimple_min_invariant (step
))
1522 /* Do not adjust ranges when chrec may wrap. */
1523 if (scev_probably_wraps_p (chrec_type (chrec
), init
, step
, stmt
,
1524 cfg_loops
->parray
[CHREC_VARIABLE (chrec
)],
1528 if (!POINTER_TYPE_P (TREE_TYPE (init
))
1529 && (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
))
1531 /* For VARYING or UNDEFINED ranges, just about anything we get
1532 from scalar evolutions should be better. */
1534 set_value_range (vr
, VR_RANGE
, TYPE_MIN_VALUE (TREE_TYPE (init
)),
1537 set_value_range (vr
, VR_RANGE
, init
, TYPE_MAX_VALUE (TREE_TYPE (init
)),
1540 else if (vr
->type
== VR_RANGE
)
1547 /* INIT is the maximum value. If INIT is lower than VR->MAX
1548 but no smaller than VR->MIN, set VR->MAX to INIT. */
1549 if (compare_values (init
, max
) == -1)
1553 /* If we just created an invalid range with the minimum
1554 greater than the maximum, take the minimum all the
1556 if (compare_values (min
, max
) == 1)
1557 min
= TYPE_MIN_VALUE (TREE_TYPE (min
));
1562 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
1563 if (compare_values (init
, min
) == 1)
1567 /* If we just created an invalid range with the minimum
1568 greater than the maximum, take the maximum all the
1570 if (compare_values (min
, max
) == 1)
1571 max
= TYPE_MAX_VALUE (TREE_TYPE (max
));
1575 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
1580 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
1582 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
1583 all the values in the ranges.
1585 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
1587 - Return NULL_TREE if it is not always possible to determine the
1588 value of the comparison. */
1592 compare_ranges (enum tree_code comp
, value_range_t
*vr0
, value_range_t
*vr1
)
1594 /* VARYING or UNDEFINED ranges cannot be compared. */
1595 if (vr0
->type
== VR_VARYING
1596 || vr0
->type
== VR_UNDEFINED
1597 || vr1
->type
== VR_VARYING
1598 || vr1
->type
== VR_UNDEFINED
)
1601 /* Anti-ranges need to be handled separately. */
1602 if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
1604 /* If both are anti-ranges, then we cannot compute any
1606 if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
1609 /* These comparisons are never statically computable. */
1616 /* Equality can be computed only between a range and an
1617 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
1618 if (vr0
->type
== VR_RANGE
)
1620 /* To simplify processing, make VR0 the anti-range. */
1621 value_range_t
*tmp
= vr0
;
1626 gcc_assert (comp
== NE_EXPR
|| comp
== EQ_EXPR
);
1628 if (compare_values (vr0
->min
, vr1
->min
) == 0
1629 && compare_values (vr0
->max
, vr1
->max
) == 0)
1630 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
1635 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
1636 operands around and change the comparison code. */
1637 if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
1640 comp
= (comp
== GT_EXPR
) ? LT_EXPR
: LE_EXPR
;
1646 if (comp
== EQ_EXPR
)
1648 /* Equality may only be computed if both ranges represent
1649 exactly one value. */
1650 if (compare_values (vr0
->min
, vr0
->max
) == 0
1651 && compare_values (vr1
->min
, vr1
->max
) == 0)
1653 int cmp_min
= compare_values (vr0
->min
, vr1
->min
);
1654 int cmp_max
= compare_values (vr0
->max
, vr1
->max
);
1655 if (cmp_min
== 0 && cmp_max
== 0)
1656 return boolean_true_node
;
1657 else if (cmp_min
!= -2 && cmp_max
!= -2)
1658 return boolean_false_node
;
1663 else if (comp
== NE_EXPR
)
1667 /* If VR0 is completely to the left or completely to the right
1668 of VR1, they are always different. Notice that we need to
1669 make sure that both comparisons yield similar results to
1670 avoid comparing values that cannot be compared at
1672 cmp1
= compare_values (vr0
->max
, vr1
->min
);
1673 cmp2
= compare_values (vr0
->min
, vr1
->max
);
1674 if ((cmp1
== -1 && cmp2
== -1) || (cmp1
== 1 && cmp2
== 1))
1675 return boolean_true_node
;
1677 /* If VR0 and VR1 represent a single value and are identical,
1679 else if (compare_values (vr0
->min
, vr0
->max
) == 0
1680 && compare_values (vr1
->min
, vr1
->max
) == 0
1681 && compare_values (vr0
->min
, vr1
->min
) == 0
1682 && compare_values (vr0
->max
, vr1
->max
) == 0)
1683 return boolean_false_node
;
1685 /* Otherwise, they may or may not be different. */
1689 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
1693 /* If VR0 is to the left of VR1, return true. */
1694 tst
= compare_values (vr0
->max
, vr1
->min
);
1695 if ((comp
== LT_EXPR
&& tst
== -1)
1696 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
1697 return boolean_true_node
;
1699 /* If VR0 is to the right of VR1, return false. */
1700 tst
= compare_values (vr0
->min
, vr1
->max
);
1701 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
1702 || (comp
== LE_EXPR
&& tst
== 1))
1703 return boolean_false_node
;
1705 /* Otherwise, we don't know. */
1713 /* Given a value range VR, a value VAL and a comparison code COMP, return
1714 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
1715 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
1716 always returns false. Return NULL_TREE if it is not always
1717 possible to determine the value of the comparison. */
1720 compare_range_with_value (enum tree_code comp
, value_range_t
*vr
, tree val
)
1722 if (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
)
1725 /* Anti-ranges need to be handled separately. */
1726 if (vr
->type
== VR_ANTI_RANGE
)
1728 /* For anti-ranges, the only predicates that we can compute at
1729 compile time are equality and inequality. */
1736 /* ~[VAL, VAL] == VAL is always false. */
1737 if (compare_values (vr
->min
, val
) == 0
1738 && compare_values (vr
->max
, val
) == 0)
1739 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
1744 if (comp
== EQ_EXPR
)
1746 /* EQ_EXPR may only be computed if VR represents exactly
1748 if (compare_values (vr
->min
, vr
->max
) == 0)
1750 int cmp
= compare_values (vr
->min
, val
);
1752 return boolean_true_node
;
1753 else if (cmp
== -1 || cmp
== 1 || cmp
== 2)
1754 return boolean_false_node
;
1756 else if (compare_values (val
, vr
->min
) == -1
1757 || compare_values (vr
->max
, val
) == -1)
1758 return boolean_false_node
;
1762 else if (comp
== NE_EXPR
)
1764 /* If VAL is not inside VR, then they are always different. */
1765 if (compare_values (vr
->max
, val
) == -1
1766 || compare_values (vr
->min
, val
) == 1)
1767 return boolean_true_node
;
1769 /* If VR represents exactly one value equal to VAL, then return
1771 if (compare_values (vr
->min
, vr
->max
) == 0
1772 && compare_values (vr
->min
, val
) == 0)
1773 return boolean_false_node
;
1775 /* Otherwise, they may or may not be different. */
1778 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
1782 /* If VR is to the left of VAL, return true. */
1783 tst
= compare_values (vr
->max
, val
);
1784 if ((comp
== LT_EXPR
&& tst
== -1)
1785 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
1786 return boolean_true_node
;
1788 /* If VR is to the right of VAL, return false. */
1789 tst
= compare_values (vr
->min
, val
);
1790 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
1791 || (comp
== LE_EXPR
&& tst
== 1))
1792 return boolean_false_node
;
1794 /* Otherwise, we don't know. */
1797 else if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
1801 /* If VR is to the right of VAL, return true. */
1802 tst
= compare_values (vr
->min
, val
);
1803 if ((comp
== GT_EXPR
&& tst
== 1)
1804 || (comp
== GE_EXPR
&& (tst
== 0 || tst
== 1)))
1805 return boolean_true_node
;
1807 /* If VR is to the left of VAL, return false. */
1808 tst
= compare_values (vr
->max
, val
);
1809 if ((comp
== GT_EXPR
&& (tst
== -1 || tst
== 0))
1810 || (comp
== GE_EXPR
&& tst
== -1))
1811 return boolean_false_node
;
1813 /* Otherwise, we don't know. */
1821 /* Debugging dumps. */
1823 void dump_value_range (FILE *, value_range_t
*);
1824 void debug_value_range (value_range_t
*);
1825 void dump_all_value_ranges (FILE *);
1826 void debug_all_value_ranges (void);
1827 void dump_vr_equiv (FILE *, bitmap
);
1828 void debug_vr_equiv (bitmap
);
1831 /* Dump value range VR to FILE. */
1834 dump_value_range (FILE *file
, value_range_t
*vr
)
1837 fprintf (file
, "[]");
1838 else if (vr
->type
== VR_UNDEFINED
)
1839 fprintf (file
, "UNDEFINED");
1840 else if (vr
->type
== VR_RANGE
|| vr
->type
== VR_ANTI_RANGE
)
1842 tree type
= TREE_TYPE (vr
->min
);
1844 fprintf (file
, "%s[", (vr
->type
== VR_ANTI_RANGE
) ? "~" : "");
1846 if (INTEGRAL_TYPE_P (type
)
1847 && !TYPE_UNSIGNED (type
)
1848 && vr
->min
== TYPE_MIN_VALUE (type
))
1849 fprintf (file
, "-INF");
1851 print_generic_expr (file
, vr
->min
, 0);
1853 fprintf (file
, ", ");
1855 if (INTEGRAL_TYPE_P (type
)
1856 && vr
->max
== TYPE_MAX_VALUE (type
))
1857 fprintf (file
, "+INF");
1859 print_generic_expr (file
, vr
->max
, 0);
1861 fprintf (file
, "]");
1868 fprintf (file
, " EQUIVALENCES: { ");
1870 EXECUTE_IF_SET_IN_BITMAP (vr
->equiv
, 0, i
, bi
)
1872 print_generic_expr (file
, ssa_name (i
), 0);
1873 fprintf (file
, " ");
1877 fprintf (file
, "} (%u elements)", c
);
1880 else if (vr
->type
== VR_VARYING
)
1881 fprintf (file
, "VARYING");
1883 fprintf (file
, "INVALID RANGE");
1887 /* Dump value range VR to stderr. */
1890 debug_value_range (value_range_t
*vr
)
1892 dump_value_range (stderr
, vr
);
1896 /* Dump value ranges of all SSA_NAMEs to FILE. */
1899 dump_all_value_ranges (FILE *file
)
1903 for (i
= 0; i
< num_ssa_names
; i
++)
1907 print_generic_expr (file
, ssa_name (i
), 0);
1908 fprintf (file
, ": ");
1909 dump_value_range (file
, vr_value
[i
]);
1910 fprintf (file
, "\n");
1914 fprintf (file
, "\n");
1918 /* Dump all value ranges to stderr. */
1921 debug_all_value_ranges (void)
1923 dump_all_value_ranges (stderr
);
1927 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
1928 create a new SSA name N and return the assertion assignment
1929 'V = ASSERT_EXPR <V, V OP W>'. */
1932 build_assert_expr_for (tree cond
, tree v
)
1936 gcc_assert (TREE_CODE (v
) == SSA_NAME
);
1937 n
= duplicate_ssa_name (v
, NULL_TREE
);
1939 if (COMPARISON_CLASS_P (cond
))
1941 tree a
= build (ASSERT_EXPR
, TREE_TYPE (v
), v
, cond
);
1942 assertion
= build (MODIFY_EXPR
, TREE_TYPE (v
), n
, a
);
1944 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
)
1946 /* Given !V, build the assignment N = false. */
1947 tree op0
= TREE_OPERAND (cond
, 0);
1948 gcc_assert (op0
== v
);
1949 assertion
= build (MODIFY_EXPR
, TREE_TYPE (v
), n
, boolean_false_node
);
1951 else if (TREE_CODE (cond
) == SSA_NAME
)
1953 /* Given V, build the assignment N = true. */
1954 gcc_assert (v
== cond
);
1955 assertion
= build (MODIFY_EXPR
, TREE_TYPE (v
), n
, boolean_true_node
);
1960 SSA_NAME_DEF_STMT (n
) = assertion
;
1962 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
1963 operand of the ASSERT_EXPR. Register the new name and the old one
1964 in the replacement table so that we can fix the SSA web after
1965 adding all the ASSERT_EXPRs. */
1966 register_new_name_mapping (n
, v
);
1972 /* Return false if EXPR is a predicate expression involving floating
1976 fp_predicate (tree expr
)
1978 return (COMPARISON_CLASS_P (expr
)
1979 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr
, 0))));
1983 /* If the range of values taken by OP can be inferred after STMT executes,
1984 return the comparison code (COMP_CODE_P) and value (VAL_P) that
1985 describes the inferred range. Return true if a range could be
1989 infer_value_range (tree stmt
, tree op
, enum tree_code
*comp_code_p
, tree
*val_p
)
1992 *comp_code_p
= ERROR_MARK
;
1994 /* Do not attempt to infer anything in names that flow through
1996 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op
))
1999 /* Similarly, don't infer anything from statements that may throw
2001 if (tree_could_throw_p (stmt
))
2004 if (POINTER_TYPE_P (TREE_TYPE (op
)))
2007 unsigned num_uses
, num_derefs
;
2009 count_uses_and_derefs (op
, stmt
, &num_uses
, &num_derefs
, &is_store
);
2010 if (num_derefs
> 0 && flag_delete_null_pointer_checks
)
2012 /* We can only assume that a pointer dereference will yield
2013 non-NULL if -fdelete-null-pointer-checks is enabled. */
2014 *val_p
= build_int_cst (TREE_TYPE (op
), 0);
2015 *comp_code_p
= NE_EXPR
;
2024 void dump_asserts_for (FILE *, tree
);
2025 void debug_asserts_for (tree
);
2026 void dump_all_asserts (FILE *);
2027 void debug_all_asserts (void);
2029 /* Dump all the registered assertions for NAME to FILE. */
2032 dump_asserts_for (FILE *file
, tree name
)
2036 fprintf (file
, "Assertions to be inserted for ");
2037 print_generic_expr (file
, name
, 0);
2038 fprintf (file
, "\n");
2040 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
2043 fprintf (file
, "\t");
2044 print_generic_expr (file
, bsi_stmt (loc
->si
), 0);
2045 fprintf (file
, "\n\tBB #%d", loc
->bb
->index
);
2048 fprintf (file
, "\n\tEDGE %d->%d", loc
->e
->src
->index
,
2049 loc
->e
->dest
->index
);
2050 dump_edge_info (file
, loc
->e
, 0);
2052 fprintf (file
, "\n\tPREDICATE: ");
2053 print_generic_expr (file
, name
, 0);
2054 fprintf (file
, " %s ", tree_code_name
[(int)loc
->comp_code
]);
2055 print_generic_expr (file
, loc
->val
, 0);
2056 fprintf (file
, "\n\n");
2060 fprintf (file
, "\n");
2064 /* Dump all the registered assertions for NAME to stderr. */
2067 debug_asserts_for (tree name
)
2069 dump_asserts_for (stderr
, name
);
2073 /* Dump all the registered assertions for all the names to FILE. */
2076 dump_all_asserts (FILE *file
)
2081 fprintf (file
, "\nASSERT_EXPRs to be inserted\n\n");
2082 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
2083 dump_asserts_for (file
, ssa_name (i
));
2084 fprintf (file
, "\n");
2088 /* Dump all the registered assertions for all the names to stderr. */
2091 debug_all_asserts (void)
2093 dump_all_asserts (stderr
);
2097 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
2098 'NAME COMP_CODE VAL' at a location that dominates block BB or
2099 E->DEST, then register this location as a possible insertion point
2100 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
2102 BB, E and SI provide the exact insertion point for the new
2103 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
2104 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
2105 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
2106 must not be NULL. */
2109 register_new_assert_for (tree name
,
2110 enum tree_code comp_code
,
2114 block_stmt_iterator si
)
2116 assert_locus_t n
, loc
, last_loc
;
2118 basic_block dest_bb
;
2120 #if defined ENABLE_CHECKING
2121 gcc_assert (bb
== NULL
|| e
== NULL
);
2124 gcc_assert (TREE_CODE (bsi_stmt (si
)) != COND_EXPR
2125 && TREE_CODE (bsi_stmt (si
)) != SWITCH_EXPR
);
2128 /* The new assertion A will be inserted at BB or E. We need to
2129 determine if the new location is dominated by a previously
2130 registered location for A. If we are doing an edge insertion,
2131 assume that A will be inserted at E->DEST. Note that this is not
2134 If E is a critical edge, it will be split. But even if E is
2135 split, the new block will dominate the same set of blocks that
2138 The reverse, however, is not true, blocks dominated by E->DEST
2139 will not be dominated by the new block created to split E. So,
2140 if the insertion location is on a critical edge, we will not use
2141 the new location to move another assertion previously registered
2142 at a block dominated by E->DEST. */
2143 dest_bb
= (bb
) ? bb
: e
->dest
;
2145 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
2146 VAL at a block dominating DEST_BB, then we don't need to insert a new
2147 one. Similarly, if the same assertion already exists at a block
2148 dominated by DEST_BB and the new location is not on a critical
2149 edge, then update the existing location for the assertion (i.e.,
2150 move the assertion up in the dominance tree).
2152 Note, this is implemented as a simple linked list because there
2153 should not be more than a handful of assertions registered per
2154 name. If this becomes a performance problem, a table hashed by
2155 COMP_CODE and VAL could be implemented. */
2156 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
2161 if (loc
->comp_code
== comp_code
2163 || operand_equal_p (loc
->val
, val
, 0)))
2165 /* If the assertion NAME COMP_CODE VAL has already been
2166 registered at a basic block that dominates DEST_BB, then
2167 we don't need to insert the same assertion again. Note
2168 that we don't check strict dominance here to avoid
2169 replicating the same assertion inside the same basic
2170 block more than once (e.g., when a pointer is
2171 dereferenced several times inside a block).
2173 An exception to this rule are edge insertions. If the
2174 new assertion is to be inserted on edge E, then it will
2175 dominate all the other insertions that we may want to
2176 insert in DEST_BB. So, if we are doing an edge
2177 insertion, don't do this dominance check. */
2179 && dominated_by_p (CDI_DOMINATORS
, dest_bb
, loc
->bb
))
2182 /* Otherwise, if E is not a critical edge and DEST_BB
2183 dominates the existing location for the assertion, move
2184 the assertion up in the dominance tree by updating its
2185 location information. */
2186 if ((e
== NULL
|| !EDGE_CRITICAL_P (e
))
2187 && dominated_by_p (CDI_DOMINATORS
, loc
->bb
, dest_bb
))
2196 /* Update the last node of the list and move to the next one. */
2201 /* If we didn't find an assertion already registered for
2202 NAME COMP_CODE VAL, add a new one at the end of the list of
2203 assertions associated with NAME. */
2204 n
= xmalloc (sizeof (*n
));
2208 n
->comp_code
= comp_code
;
2215 asserts_for
[SSA_NAME_VERSION (name
)] = n
;
2217 bitmap_set_bit (need_assert_for
, SSA_NAME_VERSION (name
));
2221 /* Try to register an edge assertion for SSA name NAME on edge E for
2222 the conditional jump pointed by SI. Return true if an assertion
2223 for NAME could be registered. */
2226 register_edge_assert_for (tree name
, edge e
, block_stmt_iterator si
)
2229 enum tree_code comp_code
;
2231 stmt
= bsi_stmt (si
);
2233 /* Do not attempt to infer anything in names that flow through
2235 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name
))
2238 /* If NAME was not found in the sub-graph reachable from E, then
2239 there's nothing to do. */
2240 if (!TEST_BIT (found_in_subgraph
, SSA_NAME_VERSION (name
)))
2243 /* We found a use of NAME in the sub-graph rooted at E->DEST.
2244 Register an assertion for NAME according to the value that NAME
2246 if (TREE_CODE (stmt
) == COND_EXPR
)
2248 /* If BB ends in a COND_EXPR then NAME then we should insert
2249 the original predicate on EDGE_TRUE_VALUE and the
2250 opposite predicate on EDGE_FALSE_VALUE. */
2251 tree cond
= COND_EXPR_COND (stmt
);
2252 bool is_else_edge
= (e
->flags
& EDGE_FALSE_VALUE
) != 0;
2254 /* Predicates may be a single SSA name or NAME OP VAL. */
2257 /* If the predicate is a name, it must be NAME, in which
2258 case we create the predicate NAME == true or
2259 NAME == false accordingly. */
2260 comp_code
= EQ_EXPR
;
2261 val
= (is_else_edge
) ? boolean_false_node
: boolean_true_node
;
2265 /* Otherwise, we have a comparison of the form NAME COMP VAL
2266 or VAL COMP NAME. */
2267 if (name
== TREE_OPERAND (cond
, 1))
2269 /* If the predicate is of the form VAL COMP NAME, flip
2270 COMP around because we need to register NAME as the
2271 first operand in the predicate. */
2272 comp_code
= swap_tree_comparison (TREE_CODE (cond
));
2273 val
= TREE_OPERAND (cond
, 0);
2277 /* The comparison is of the form NAME COMP VAL, so the
2278 comparison code remains unchanged. */
2279 comp_code
= TREE_CODE (cond
);
2280 val
= TREE_OPERAND (cond
, 1);
2283 /* If we are inserting the assertion on the ELSE edge, we
2284 need to invert the sign comparison. */
2286 comp_code
= invert_tree_comparison (comp_code
, 0);
2291 /* FIXME. Handle SWITCH_EXPR. */
2295 register_new_assert_for (name
, comp_code
, val
, NULL
, e
, si
);
2300 static bool find_assert_locations (basic_block bb
);
2302 /* Determine whether the outgoing edges of BB should receive an
2303 ASSERT_EXPR for each of the operands of BB's last statement. The
2304 last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
2306 If any of the sub-graphs rooted at BB have an interesting use of
2307 the predicate operands, an assert location node is added to the
2308 list of assertions for the corresponding operands. */
2311 find_conditional_asserts (basic_block bb
)
2314 block_stmt_iterator last_si
;
2320 need_assert
= false;
2321 last_si
= bsi_last (bb
);
2322 last
= bsi_stmt (last_si
);
2324 /* Look for uses of the operands in each of the sub-graphs
2325 rooted at BB. We need to check each of the outgoing edges
2326 separately, so that we know what kind of ASSERT_EXPR to
2328 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
2333 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
2334 Otherwise, when we finish traversing each of the sub-graphs, we
2335 won't know whether the variables were found in the sub-graphs or
2336 if they had been found in a block upstream from BB. */
2337 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
2338 RESET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
2340 /* Traverse the strictly dominated sub-graph rooted at E->DEST
2341 to determine if any of the operands in the conditional
2342 predicate are used. */
2344 need_assert
|= find_assert_locations (e
->dest
);
2346 /* Register the necessary assertions for each operand in the
2347 conditional predicate. */
2348 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
2349 need_assert
|= register_edge_assert_for (op
, e
, last_si
);
2352 /* Finally, indicate that we have found the operands in the
2354 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
2355 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
2361 /* Traverse all the statements in block BB looking for statements that
2362 may generate useful assertions for the SSA names in their operand.
2363 If a statement produces a useful assertion A for name N_i, then the
2364 list of assertions already generated for N_i is scanned to
2365 determine if A is actually needed.
2367 If N_i already had the assertion A at a location dominating the
2368 current location, then nothing needs to be done. Otherwise, the
2369 new location for A is recorded instead.
2371 1- For every statement S in BB, all the variables used by S are
2372 added to bitmap FOUND_IN_SUBGRAPH.
2374 2- If statement S uses an operand N in a way that exposes a known
2375 value range for N, then if N was not already generated by an
2376 ASSERT_EXPR, create a new assert location for N. For instance,
2377 if N is a pointer and the statement dereferences it, we can
2378 assume that N is not NULL.
2380 3- COND_EXPRs are a special case of #2. We can derive range
2381 information from the predicate but need to insert different
2382 ASSERT_EXPRs for each of the sub-graphs rooted at the
2383 conditional block. If the last statement of BB is a conditional
2384 expression of the form 'X op Y', then
2386 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
2388 b) If the conditional is the only entry point to the sub-graph
2389 corresponding to the THEN_CLAUSE, recurse into it. On
2390 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
2391 an ASSERT_EXPR is added for the corresponding variable.
2393 c) Repeat step (b) on the ELSE_CLAUSE.
2395 d) Mark X and Y in FOUND_IN_SUBGRAPH.
2404 In this case, an assertion on the THEN clause is useful to
2405 determine that 'a' is always 9 on that edge. However, an assertion
2406 on the ELSE clause would be unnecessary.
2408 4- If BB does not end in a conditional expression, then we recurse
2409 into BB's dominator children.
2411 At the end of the recursive traversal, every SSA name will have a
2412 list of locations where ASSERT_EXPRs should be added. When a new
2413 location for name N is found, it is registered by calling
2414 register_new_assert_for. That function keeps track of all the
2415 registered assertions to prevent adding unnecessary assertions.
2416 For instance, if a pointer P_4 is dereferenced more than once in a
2417 dominator tree, only the location dominating all the dereference of
2418 P_4 will receive an ASSERT_EXPR.
2420 If this function returns true, then it means that there are names
2421 for which we need to generate ASSERT_EXPRs. Those assertions are
2422 inserted by process_assert_insertions.
2424 TODO. Handle SWITCH_EXPR. */
2427 find_assert_locations (basic_block bb
)
2429 block_stmt_iterator si
;
2434 if (TEST_BIT (blocks_visited
, bb
->index
))
2437 SET_BIT (blocks_visited
, bb
->index
);
2439 need_assert
= false;
2441 /* Traverse all PHI nodes in BB marking used operands. */
2442 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
2444 use_operand_p arg_p
;
2447 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_USE
)
2449 tree arg
= USE_FROM_PTR (arg_p
);
2450 if (TREE_CODE (arg
) == SSA_NAME
)
2452 gcc_assert (is_gimple_reg (PHI_RESULT (phi
)));
2453 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (arg
));
2458 /* Traverse all the statements in BB marking used names and looking
2459 for statements that may infer assertions for their used operands. */
2461 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
2466 stmt
= bsi_stmt (si
);
2468 /* See if we can derive an assertion for any of STMT's operands. */
2469 FOR_EACH_SSA_TREE_OPERAND (op
, stmt
, i
, SSA_OP_USE
)
2472 enum tree_code comp_code
;
2474 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
2475 the sub-graph of a conditional block, when we return from
2476 this recursive walk, our parent will use the
2477 FOUND_IN_SUBGRAPH bitset to determine if one of the
2478 operands it was looking for was present in the sub-graph. */
2479 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
2481 /* If OP is used only once, namely in this STMT, don't
2482 bother creating an ASSERT_EXPR for it. Such an
2483 ASSERT_EXPR would do nothing but increase compile time.
2484 Experiments show that with this simple check, we can save
2485 more than 20% of ASSERT_EXPRs. */
2486 if (has_single_use (op
))
2489 /* If OP is used in such a way that we can infer a value
2490 range for it, and we don't find a previous assertion for
2491 it, create a new assertion location node for OP. */
2492 if (infer_value_range (stmt
, op
, &comp_code
, &value
))
2494 register_new_assert_for (op
, comp_code
, value
, bb
, NULL
, si
);
2499 /* Remember the last statement of the block. */
2503 /* If BB's last statement is a conditional expression
2504 involving integer operands, recurse into each of the sub-graphs
2505 rooted at BB to determine if we need to add ASSERT_EXPRs. */
2507 && TREE_CODE (last
) == COND_EXPR
2508 && !fp_predicate (COND_EXPR_COND (last
))
2509 && !ZERO_SSA_OPERANDS (last
, SSA_OP_USE
))
2510 need_assert
|= find_conditional_asserts (bb
);
2512 /* Recurse into the dominator children of BB. */
2513 for (son
= first_dom_son (CDI_DOMINATORS
, bb
);
2515 son
= next_dom_son (CDI_DOMINATORS
, son
))
2516 need_assert
|= find_assert_locations (son
);
2522 /* Create an ASSERT_EXPR for NAME and insert it in the location
2523 indicated by LOC. Return true if we made any edge insertions. */
2526 process_assert_insertions_for (tree name
, assert_locus_t loc
)
2528 /* Build the comparison expression NAME_i COMP_CODE VAL. */
2529 tree stmt
, cond
, assert_expr
;
2533 cond
= build (loc
->comp_code
, boolean_type_node
, name
, loc
->val
);
2534 assert_expr
= build_assert_expr_for (cond
, name
);
2538 /* We have been asked to insert the assertion on an edge. This
2539 is used only by COND_EXPR and SWITCH_EXPR assertions. */
2540 #if defined ENABLE_CHECKING
2541 gcc_assert (TREE_CODE (bsi_stmt (loc
->si
)) == COND_EXPR
2542 || TREE_CODE (bsi_stmt (loc
->si
)) == SWITCH_EXPR
);
2545 bsi_insert_on_edge (loc
->e
, assert_expr
);
2549 /* Otherwise, we can insert right after LOC->SI iff the
2550 statement must not be the last statement in the block. */
2551 stmt
= bsi_stmt (loc
->si
);
2552 if (!stmt_ends_bb_p (stmt
))
2554 bsi_insert_after (&loc
->si
, assert_expr
, BSI_SAME_STMT
);
2558 /* If STMT must be the last statement in BB, we can only insert new
2559 assertions on the non-abnormal edge out of BB. Note that since
2560 STMT is not control flow, there may only be one non-abnormal edge
2562 FOR_EACH_EDGE (e
, ei
, loc
->bb
->succs
)
2563 if (!(e
->flags
& EDGE_ABNORMAL
))
2565 bsi_insert_on_edge (e
, assert_expr
);
2573 /* Process all the insertions registered for every name N_i registered
2574 in NEED_ASSERT_FOR. The list of assertions to be inserted are
2575 found in ASSERTS_FOR[i]. */
2578 process_assert_insertions (void)
2582 bool update_edges_p
= false;
2583 int num_asserts
= 0;
2585 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2586 dump_all_asserts (dump_file
);
2588 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
2590 assert_locus_t loc
= asserts_for
[i
];
2595 assert_locus_t next
= loc
->next
;
2596 update_edges_p
|= process_assert_insertions_for (ssa_name (i
), loc
);
2604 bsi_commit_edge_inserts ();
2606 if (dump_file
&& (dump_flags
& TDF_STATS
))
2607 fprintf (dump_file
, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
2612 /* Traverse the flowgraph looking for conditional jumps to insert range
2613 expressions. These range expressions are meant to provide information
2614 to optimizations that need to reason in terms of value ranges. They
2615 will not be expanded into RTL. For instance, given:
2624 this pass will transform the code into:
2630 x = ASSERT_EXPR <x, x < y>
2635 y = ASSERT_EXPR <y, x <= y>
2639 The idea is that once copy and constant propagation have run, other
2640 optimizations will be able to determine what ranges of values can 'x'
2641 take in different paths of the code, simply by checking the reaching
2642 definition of 'x'. */
2645 insert_range_assertions (void)
2651 found_in_subgraph
= sbitmap_alloc (num_ssa_names
);
2652 sbitmap_zero (found_in_subgraph
);
2654 blocks_visited
= sbitmap_alloc (last_basic_block
);
2655 sbitmap_zero (blocks_visited
);
2657 need_assert_for
= BITMAP_ALLOC (NULL
);
2658 asserts_for
= xmalloc (num_ssa_names
* sizeof (assert_locus_t
));
2659 memset (asserts_for
, 0, num_ssa_names
* sizeof (assert_locus_t
));
2661 calculate_dominance_info (CDI_DOMINATORS
);
2663 update_ssa_p
= false;
2664 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
2665 if (find_assert_locations (e
->dest
))
2666 update_ssa_p
= true;
2670 process_assert_insertions ();
2671 update_ssa (TODO_update_ssa_no_phi
);
2674 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2676 fprintf (dump_file
, "\nSSA form after inserting ASSERT_EXPRs\n");
2677 dump_function_to_file (current_function_decl
, dump_file
, dump_flags
);
2680 sbitmap_free (found_in_subgraph
);
2682 BITMAP_FREE (need_assert_for
);
2686 /* Convert range assertion expressions into the implied copies and
2687 copy propagate away the copies. Doing the trivial copy propagation
2688 here avoids the need to run the full copy propagation pass after
2691 FIXME, this will eventually lead to copy propagation removing the
2692 names that had useful range information attached to them. For
2693 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
2694 then N_i will have the range [3, +INF].
2696 However, by converting the assertion into the implied copy
2697 operation N_i = N_j, we will then copy-propagate N_j into the uses
2698 of N_i and lose the range information. We may want to hold on to
2699 ASSERT_EXPRs a little while longer as the ranges could be used in
2700 things like jump threading.
2702 The problem with keeping ASSERT_EXPRs around is that passes after
2703 VRP need to handle them appropriately.
2705 Another approach would be to make the range information a first
2706 class property of the SSA_NAME so that it can be queried from
2707 any pass. This is made somewhat more complex by the need for
2708 multiple ranges to be associated with one SSA_NAME. */
2711 remove_range_assertions (void)
2714 block_stmt_iterator si
;
2716 /* Note that the BSI iterator bump happens at the bottom of the
2717 loop and no bump is necessary if we're removing the statement
2718 referenced by the current BSI. */
2720 for (si
= bsi_start (bb
); !bsi_end_p (si
);)
2722 tree stmt
= bsi_stmt (si
);
2724 if (TREE_CODE (stmt
) == MODIFY_EXPR
2725 && TREE_CODE (TREE_OPERAND (stmt
, 1)) == ASSERT_EXPR
)
2727 tree rhs
= TREE_OPERAND (stmt
, 1);
2728 tree cond
= fold (ASSERT_EXPR_COND (rhs
));
2729 use_operand_p use_p
;
2730 imm_use_iterator iter
;
2732 gcc_assert (cond
!= boolean_false_node
);
2733 TREE_OPERAND (stmt
, 1) = ASSERT_EXPR_VAR (rhs
);
2736 /* The statement is now a copy. Propagate the RHS into
2737 every use of the LHS. */
2738 FOR_EACH_IMM_USE_SAFE (use_p
, iter
, TREE_OPERAND (stmt
, 0))
2740 SET_USE (use_p
, ASSERT_EXPR_VAR (rhs
));
2741 update_stmt (USE_STMT (use_p
));
2744 /* And finally, remove the copy, it is not needed. */
2753 /* Return true if STMT is interesting for VRP. */
2756 stmt_interesting_for_vrp (tree stmt
)
2758 if (TREE_CODE (stmt
) == PHI_NODE
2759 && is_gimple_reg (PHI_RESULT (stmt
))
2760 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))
2761 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))))
2763 else if (TREE_CODE (stmt
) == MODIFY_EXPR
)
2765 tree lhs
= TREE_OPERAND (stmt
, 0);
2767 if (TREE_CODE (lhs
) == SSA_NAME
2768 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
2769 || POINTER_TYPE_P (TREE_TYPE (lhs
)))
2770 && ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
2773 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
2780 /* Initialize local data structures for VRP. Return true if VRP
2781 is worth running (i.e. if we found any statements that could
2782 benefit from range information). */
2785 vrp_initialize (void)
2789 vr_value
= xmalloc (num_ssa_names
* sizeof (value_range_t
*));
2790 memset (vr_value
, 0, num_ssa_names
* sizeof (value_range_t
*));
2794 block_stmt_iterator si
;
2797 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
2799 if (!stmt_interesting_for_vrp (phi
))
2801 tree lhs
= PHI_RESULT (phi
);
2802 set_value_range_to_varying (get_value_range (lhs
));
2803 DONT_SIMULATE_AGAIN (phi
) = true;
2806 DONT_SIMULATE_AGAIN (phi
) = false;
2809 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
2811 tree stmt
= bsi_stmt (si
);
2813 if (!stmt_interesting_for_vrp (stmt
))
2817 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, i
, SSA_OP_DEF
)
2818 set_value_range_to_varying (get_value_range (def
));
2819 DONT_SIMULATE_AGAIN (stmt
) = true;
2823 DONT_SIMULATE_AGAIN (stmt
) = false;
2830 /* Visit assignment STMT. If it produces an interesting range, record
2831 the SSA name in *OUTPUT_P. */
2833 static enum ssa_prop_result
2834 vrp_visit_assignment (tree stmt
, tree
*output_p
)
2839 lhs
= TREE_OPERAND (stmt
, 0);
2840 rhs
= TREE_OPERAND (stmt
, 1);
2842 /* We only keep track of ranges in integral and pointer types. */
2843 if (TREE_CODE (lhs
) == SSA_NAME
2844 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
2845 || POINTER_TYPE_P (TREE_TYPE (lhs
))))
2848 value_range_t new_vr
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
2850 extract_range_from_expr (&new_vr
, rhs
);
2852 /* If STMT is inside a loop, we may be able to know something
2853 else about the range of LHS by examining scalar evolution
2855 if (cfg_loops
&& (l
= loop_containing_stmt (stmt
)))
2856 adjust_range_with_scev (&new_vr
, l
, stmt
, lhs
);
2858 if (update_value_range (lhs
, &new_vr
))
2862 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2864 fprintf (dump_file
, "Found new range for ");
2865 print_generic_expr (dump_file
, lhs
, 0);
2866 fprintf (dump_file
, ": ");
2867 dump_value_range (dump_file
, &new_vr
);
2868 fprintf (dump_file
, "\n\n");
2871 if (new_vr
.type
== VR_VARYING
)
2872 return SSA_PROP_VARYING
;
2874 return SSA_PROP_INTERESTING
;
2877 return SSA_PROP_NOT_INTERESTING
;
2880 /* Every other statement produces no useful ranges. */
2881 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
2882 set_value_range_to_varying (get_value_range (def
));
2884 return SSA_PROP_VARYING
;
2888 /* Compare all the value ranges for names equivalent to VAR with VAL
2889 using comparison code COMP. Return the same value returned by
2890 compare_range_with_value. */
2893 compare_name_with_value (enum tree_code comp
, tree var
, tree val
)
2900 t
= retval
= NULL_TREE
;
2902 /* Get the set of equivalences for VAR. */
2903 e
= get_value_range (var
)->equiv
;
2905 /* Add VAR to its own set of equivalences so that VAR's value range
2906 is processed by this loop (otherwise, we would have to replicate
2907 the body of the loop just to check VAR's value range). */
2908 bitmap_set_bit (e
, SSA_NAME_VERSION (var
));
2910 EXECUTE_IF_SET_IN_BITMAP (e
, 0, i
, bi
)
2912 value_range_t equiv_vr
= *(vr_value
[i
]);
2914 /* If name N_i does not have a valid range, use N_i as its own
2915 range. This allows us to compare against names that may
2916 have N_i in their ranges. */
2917 if (equiv_vr
.type
== VR_VARYING
|| equiv_vr
.type
== VR_UNDEFINED
)
2919 equiv_vr
.type
= VR_RANGE
;
2920 equiv_vr
.min
= ssa_name (i
);
2921 equiv_vr
.max
= ssa_name (i
);
2924 t
= compare_range_with_value (comp
, &equiv_vr
, val
);
2927 /* All the ranges should compare the same against VAL. */
2928 gcc_assert (retval
== NULL
|| t
== retval
);
2933 /* Remove VAR from its own equivalence set. */
2934 bitmap_clear_bit (e
, SSA_NAME_VERSION (var
));
2939 /* We couldn't find a non-NULL value for the predicate. */
2944 /* Given a comparison code COMP and names N1 and N2, compare all the
2945 ranges equivalent to N1 against all the ranges equivalent to N2
2946 to determine the value of N1 COMP N2. Return the same value
2947 returned by compare_ranges. */
2950 compare_names (enum tree_code comp
, tree n1
, tree n2
)
2954 bitmap_iterator bi1
, bi2
;
2957 /* Compare the ranges of every name equivalent to N1 against the
2958 ranges of every name equivalent to N2. */
2959 e1
= get_value_range (n1
)->equiv
;
2960 e2
= get_value_range (n2
)->equiv
;
2962 /* Add N1 and N2 to their own set of equivalences to avoid
2963 duplicating the body of the loop just to check N1 and N2
2965 bitmap_set_bit (e1
, SSA_NAME_VERSION (n1
));
2966 bitmap_set_bit (e2
, SSA_NAME_VERSION (n2
));
2968 /* If the equivalence sets have a common intersection, then the two
2969 names can be compared without checking their ranges. */
2970 if (bitmap_intersect_p (e1
, e2
))
2972 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
2973 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
2975 return (comp
== EQ_EXPR
|| comp
== GE_EXPR
|| comp
== LE_EXPR
)
2977 : boolean_false_node
;
2980 /* Otherwise, compare all the equivalent ranges. First, add N1 and
2981 N2 to their own set of equivalences to avoid duplicating the body
2982 of the loop just to check N1 and N2 ranges. */
2983 EXECUTE_IF_SET_IN_BITMAP (e1
, 0, i1
, bi1
)
2985 value_range_t vr1
= *(vr_value
[i1
]);
2987 /* If the range is VARYING or UNDEFINED, use the name itself. */
2988 if (vr1
.type
== VR_VARYING
|| vr1
.type
== VR_UNDEFINED
)
2990 vr1
.type
= VR_RANGE
;
2991 vr1
.min
= ssa_name (i1
);
2992 vr1
.max
= ssa_name (i1
);
2995 t
= retval
= NULL_TREE
;
2996 EXECUTE_IF_SET_IN_BITMAP (e2
, 0, i2
, bi2
)
2998 value_range_t vr2
= *(vr_value
[i2
]);
3000 if (vr2
.type
== VR_VARYING
|| vr2
.type
== VR_UNDEFINED
)
3002 vr2
.type
= VR_RANGE
;
3003 vr2
.min
= ssa_name (i2
);
3004 vr2
.max
= ssa_name (i2
);
3007 t
= compare_ranges (comp
, &vr1
, &vr2
);
3010 /* All the ranges in the equivalent sets should compare
3012 gcc_assert (retval
== NULL
|| t
== retval
);
3019 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3020 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3025 /* None of the equivalent ranges are useful in computing this
3027 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
3028 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
3033 /* Given a conditional predicate COND, try to determine if COND yields
3034 true or false based on the value ranges of its operands. Return
3035 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
3036 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
3037 NULL if the conditional cannot be evaluated at compile time.
3039 If USE_EQUIV_P is true, the ranges of all the names equivalent with
3040 the operands in COND are used when trying to compute its value.
3041 This is only used during final substitution. During propagation,
3042 we only check the range of each variable and not its equivalents. */
3045 vrp_evaluate_conditional (tree cond
, bool use_equiv_p
)
3047 gcc_assert (TREE_CODE (cond
) == SSA_NAME
3048 || TREE_CODE_CLASS (TREE_CODE (cond
)) == tcc_comparison
);
3050 if (TREE_CODE (cond
) == SSA_NAME
)
3056 retval
= compare_name_with_value (NE_EXPR
, cond
, boolean_false_node
);
3059 value_range_t
*vr
= get_value_range (cond
);
3060 retval
= compare_range_with_value (NE_EXPR
, vr
, boolean_false_node
);
3063 /* If COND has a known boolean range, return it. */
3067 /* Otherwise, if COND has a symbolic range of exactly one value,
3069 vr
= get_value_range (cond
);
3070 if (vr
->type
== VR_RANGE
&& vr
->min
== vr
->max
)
3075 tree op0
= TREE_OPERAND (cond
, 0);
3076 tree op1
= TREE_OPERAND (cond
, 1);
3078 /* We only deal with integral and pointer types. */
3079 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
3080 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
3085 if (TREE_CODE (op0
) == SSA_NAME
&& TREE_CODE (op1
) == SSA_NAME
)
3086 return compare_names (TREE_CODE (cond
), op0
, op1
);
3087 else if (TREE_CODE (op0
) == SSA_NAME
)
3088 return compare_name_with_value (TREE_CODE (cond
), op0
, op1
);
3089 else if (TREE_CODE (op1
) == SSA_NAME
)
3090 return compare_name_with_value (
3091 swap_tree_comparison (TREE_CODE (cond
)), op1
, op0
);
3095 value_range_t
*vr0
, *vr1
;
3097 vr0
= (TREE_CODE (op0
) == SSA_NAME
) ? get_value_range (op0
) : NULL
;
3098 vr1
= (TREE_CODE (op1
) == SSA_NAME
) ? get_value_range (op1
) : NULL
;
3101 return compare_ranges (TREE_CODE (cond
), vr0
, vr1
);
3102 else if (vr0
&& vr1
== NULL
)
3103 return compare_range_with_value (TREE_CODE (cond
), vr0
, op1
);
3104 else if (vr0
== NULL
&& vr1
)
3105 return compare_range_with_value (
3106 swap_tree_comparison (TREE_CODE (cond
)), vr1
, op0
);
3110 /* Anything else cannot be computed statically. */
3115 /* Visit conditional statement STMT. If we can determine which edge
3116 will be taken out of STMT's basic block, record it in
3117 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
3118 SSA_PROP_VARYING. */
3120 static enum ssa_prop_result
3121 vrp_visit_cond_stmt (tree stmt
, edge
*taken_edge_p
)
3125 *taken_edge_p
= NULL
;
3127 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
3128 add ASSERT_EXPRs for them. */
3129 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
3130 return SSA_PROP_VARYING
;
3132 cond
= COND_EXPR_COND (stmt
);
3134 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3139 fprintf (dump_file
, "\nVisiting conditional with predicate: ");
3140 print_generic_expr (dump_file
, cond
, 0);
3141 fprintf (dump_file
, "\nWith known ranges\n");
3143 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, i
, SSA_OP_USE
)
3145 fprintf (dump_file
, "\t");
3146 print_generic_expr (dump_file
, use
, 0);
3147 fprintf (dump_file
, ": ");
3148 dump_value_range (dump_file
, vr_value
[SSA_NAME_VERSION (use
)]);
3151 fprintf (dump_file
, "\n");
3154 /* Compute the value of the predicate COND by checking the known
3155 ranges of each of its operands.
3157 Note that we cannot evaluate all the equivalent ranges here
3158 because those ranges may not yet be final and with the current
3159 propagation strategy, we cannot determine when the value ranges
3160 of the names in the equivalence set have changed.
3162 For instance, given the following code fragment
3166 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
3170 Assume that on the first visit to i_14, i_5 has the temporary
3171 range [8, 8] because the second argument to the PHI function is
3172 not yet executable. We derive the range ~[0, 0] for i_14 and the
3173 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
3174 the first time, since i_14 is equivalent to the range [8, 8], we
3175 determine that the predicate is always false.
3177 On the next round of propagation, i_13 is determined to be
3178 VARYING, which causes i_5 to drop down to VARYING. So, another
3179 visit to i_14 is scheduled. In this second visit, we compute the
3180 exact same range and equivalence set for i_14, namely ~[0, 0] and
3181 { i_5 }. But we did not have the previous range for i_5
3182 registered, so vrp_visit_assignment thinks that the range for
3183 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
3184 is not visited again, which stops propagation from visiting
3185 statements in the THEN clause of that if().
3187 To properly fix this we would need to keep the previous range
3188 value for the names in the equivalence set. This way we would've
3189 discovered that from one visit to the other i_5 changed from
3190 range [8, 8] to VR_VARYING.
3192 However, fixing this apparent limitation may not be worth the
3193 additional checking. Testing on several code bases (GCC, DLV,
3194 MICO, TRAMP3D and SPEC2000) showed that doing this results in
3195 4 more predicates folded in SPEC. */
3196 val
= vrp_evaluate_conditional (cond
, false);
3198 *taken_edge_p
= find_taken_edge (bb_for_stmt (stmt
), val
);
3200 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3202 fprintf (dump_file
, "\nPredicate evaluates to: ");
3203 if (val
== NULL_TREE
)
3204 fprintf (dump_file
, "DON'T KNOW\n");
3206 print_generic_stmt (dump_file
, val
, 0);
3209 return (*taken_edge_p
) ? SSA_PROP_INTERESTING
: SSA_PROP_VARYING
;
3213 /* Evaluate statement STMT. If the statement produces a useful range,
3214 return SSA_PROP_INTERESTING and record the SSA name with the
3215 interesting range into *OUTPUT_P.
3217 If STMT is a conditional branch and we can determine its truth
3218 value, the taken edge is recorded in *TAKEN_EDGE_P.
3220 If STMT produces a varying value, return SSA_PROP_VARYING. */
3222 static enum ssa_prop_result
3223 vrp_visit_stmt (tree stmt
, edge
*taken_edge_p
, tree
*output_p
)
3229 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3231 fprintf (dump_file
, "\nVisiting statement:\n");
3232 print_generic_stmt (dump_file
, stmt
, dump_flags
);
3233 fprintf (dump_file
, "\n");
3236 ann
= stmt_ann (stmt
);
3237 if (TREE_CODE (stmt
) == MODIFY_EXPR
3238 && ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
3239 return vrp_visit_assignment (stmt
, output_p
);
3240 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
3241 return vrp_visit_cond_stmt (stmt
, taken_edge_p
);
3243 /* All other statements produce nothing of interest for VRP, so mark
3244 their outputs varying and prevent further simulation. */
3245 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
3246 set_value_range_to_varying (get_value_range (def
));
3248 return SSA_PROP_VARYING
;
3252 /* Meet operation for value ranges. Given two value ranges VR0 and
3253 VR1, store in VR0 the result of meeting VR0 and VR1.
3255 The meeting rules are as follows:
3257 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
3259 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
3260 union of VR0 and VR1. */
3263 vrp_meet (value_range_t
*vr0
, value_range_t
*vr1
)
3265 if (vr0
->type
== VR_UNDEFINED
)
3267 copy_value_range (vr0
, vr1
);
3271 if (vr1
->type
== VR_UNDEFINED
)
3273 /* Nothing to do. VR0 already has the resulting range. */
3277 if (vr0
->type
== VR_VARYING
)
3279 /* Nothing to do. VR0 already has the resulting range. */
3283 if (vr1
->type
== VR_VARYING
)
3285 set_value_range_to_varying (vr0
);
3289 if (vr0
->type
== VR_RANGE
&& vr1
->type
== VR_RANGE
)
3291 /* If VR0 and VR1 have a non-empty intersection, compute the
3292 union of both ranges. */
3293 if (value_ranges_intersect_p (vr0
, vr1
))
3298 /* The lower limit of the new range is the minimum of the
3299 two ranges. If they cannot be compared, the result is
3301 cmp
= compare_values (vr0
->min
, vr1
->min
);
3302 if (cmp
== 0 || cmp
== 1)
3308 set_value_range_to_varying (vr0
);
3312 /* Similarly, the upper limit of the new range is the
3313 maximum of the two ranges. If they cannot be compared,
3314 the result is VARYING. */
3315 cmp
= compare_values (vr0
->max
, vr1
->max
);
3316 if (cmp
== 0 || cmp
== -1)
3322 set_value_range_to_varying (vr0
);
3326 /* The resulting set of equivalences is the intersection of
3328 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
3329 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
3331 set_value_range (vr0
, vr0
->type
, min
, max
, vr0
->equiv
);
3336 else if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
3338 /* Two anti-ranges meet only if they are both identical. */
3339 if (compare_values (vr0
->min
, vr1
->min
) == 0
3340 && compare_values (vr0
->max
, vr1
->max
) == 0
3341 && compare_values (vr0
->min
, vr0
->max
) == 0)
3343 /* The resulting set of equivalences is the intersection of
3345 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
3346 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
3351 else if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
3353 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
3354 meet only if the ranges have an empty intersection. The
3355 result of the meet operation is the anti-range. */
3356 if (!symbolic_range_p (vr0
)
3357 && !symbolic_range_p (vr1
)
3358 && !value_ranges_intersect_p (vr0
, vr1
))
3360 if (vr1
->type
== VR_ANTI_RANGE
)
3361 copy_value_range (vr0
, vr1
);
3372 /* The two range VR0 and VR1 do not meet. Before giving up and
3373 setting the result to VARYING, see if we can at least derive a
3374 useful anti-range. */
3375 if (!symbolic_range_p (vr0
)
3376 && !range_includes_zero_p (vr0
)
3377 && !symbolic_range_p (vr1
)
3378 && !range_includes_zero_p (vr1
))
3379 set_value_range_to_nonnull (vr0
, TREE_TYPE (vr0
->min
));
3381 set_value_range_to_varying (vr0
);
3385 /* Visit all arguments for PHI node PHI that flow through executable
3386 edges. If a valid value range can be derived from all the incoming
3387 value ranges, set a new range for the LHS of PHI. */
3389 static enum ssa_prop_result
3390 vrp_visit_phi_node (tree phi
)
3393 tree lhs
= PHI_RESULT (phi
);
3394 value_range_t
*lhs_vr
= get_value_range (lhs
);
3395 value_range_t vr_result
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
3397 copy_value_range (&vr_result
, lhs_vr
);
3399 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3401 fprintf (dump_file
, "\nVisiting PHI node: ");
3402 print_generic_expr (dump_file
, phi
, dump_flags
);
3405 for (i
= 0; i
< PHI_NUM_ARGS (phi
); i
++)
3407 edge e
= PHI_ARG_EDGE (phi
, i
);
3409 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3412 "\n Argument #%d (%d -> %d %sexecutable)\n",
3413 i
, e
->src
->index
, e
->dest
->index
,
3414 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
3417 if (e
->flags
& EDGE_EXECUTABLE
)
3419 tree arg
= PHI_ARG_DEF (phi
, i
);
3420 value_range_t vr_arg
;
3422 if (TREE_CODE (arg
) == SSA_NAME
)
3423 vr_arg
= *(get_value_range (arg
));
3426 vr_arg
.type
= VR_RANGE
;
3429 vr_arg
.equiv
= NULL
;
3432 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3434 fprintf (dump_file
, "\t");
3435 print_generic_expr (dump_file
, arg
, dump_flags
);
3436 fprintf (dump_file
, "\n\tValue: ");
3437 dump_value_range (dump_file
, &vr_arg
);
3438 fprintf (dump_file
, "\n");
3441 vrp_meet (&vr_result
, &vr_arg
);
3443 if (vr_result
.type
== VR_VARYING
)
3448 if (vr_result
.type
== VR_VARYING
)
3451 /* To prevent infinite iterations in the algorithm, derive ranges
3452 when the new value is slightly bigger or smaller than the
3454 if (lhs_vr
->type
== VR_RANGE
)
3456 if (!POINTER_TYPE_P (TREE_TYPE (lhs
)))
3458 int cmp_min
= compare_values (lhs_vr
->min
, vr_result
.min
);
3459 int cmp_max
= compare_values (lhs_vr
->max
, vr_result
.max
);
3461 /* If the new minimum is smaller or larger than the previous
3462 one, go all the way to -INF. In the first case, to avoid
3463 iterating millions of times to reach -INF, and in the
3464 other case to avoid infinite bouncing between different
3466 if (cmp_min
> 0 || cmp_min
< 0)
3467 vr_result
.min
= TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
));
3469 /* Similarly, if the new maximum is smaller or larger than
3470 the previous one, go all the way to +INF. */
3471 if (cmp_max
< 0 || cmp_max
> 0)
3472 vr_result
.max
= TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
));
3474 /* If we ended up with a (-INF, +INF) range, set it to
3476 if (vr_result
.min
== TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
))
3477 && vr_result
.max
== TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
)))
3482 /* If the new range is different than the previous value, keep
3484 if (update_value_range (lhs
, &vr_result
))
3485 return SSA_PROP_INTERESTING
;
3487 /* Nothing changed, don't add outgoing edges. */
3488 return SSA_PROP_NOT_INTERESTING
;
3490 /* No match found. Set the LHS to VARYING. */
3492 set_value_range_to_varying (lhs_vr
);
3493 return SSA_PROP_VARYING
;
3496 /* Walk through the IL simplifying expressions using knowledge
3500 simplify_using_ranges (void)
3506 block_stmt_iterator bsi
;
3508 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
3510 tree stmt
= bsi_stmt (bsi
);
3512 if (TREE_CODE (stmt
) == MODIFY_EXPR
)
3514 tree rhs
= TREE_OPERAND (stmt
, 1);
3515 enum tree_code rhs_code
= TREE_CODE (rhs
);
3517 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
3518 and BIT_AND_EXPR respectively if the first operand is greater
3519 than zero and the second operand is an exact power of two. */
3520 if ((rhs_code
== TRUNC_DIV_EXPR
|| rhs_code
== TRUNC_MOD_EXPR
)
3521 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0)))
3522 && integer_pow2p (TREE_OPERAND (rhs
, 1)))
3525 tree op
= TREE_OPERAND (rhs
, 0);
3526 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
3528 if (TYPE_UNSIGNED (TREE_TYPE (op
)))
3530 val
= integer_one_node
;
3534 val
= compare_range_with_value (GT_EXPR
, vr
,
3538 if (val
&& integer_onep (val
))
3541 tree op0
= TREE_OPERAND (rhs
, 0);
3542 tree op1
= TREE_OPERAND (rhs
, 1);
3544 if (rhs_code
== TRUNC_DIV_EXPR
)
3546 t
= build_int_cst (NULL_TREE
, tree_log2 (op1
));
3547 t
= build (RSHIFT_EXPR
, TREE_TYPE (op0
), op0
, t
);
3551 t
= build_int_cst (TREE_TYPE (op1
), 1);
3552 t
= int_const_binop (MINUS_EXPR
, op1
, t
, 0);
3553 t
= fold_convert (TREE_TYPE (op0
), t
);
3554 t
= build2 (BIT_AND_EXPR
, TREE_TYPE (op0
), op0
, t
);
3557 TREE_OPERAND (stmt
, 1) = t
;
3563 /* Transform ABS (X) into X or -X as appropriate. */
3564 if (rhs_code
== ABS_EXPR
3565 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == SSA_NAME
3566 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0))))
3569 tree op
= TREE_OPERAND (rhs
, 0);
3570 tree type
= TREE_TYPE (op
);
3571 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
3573 if (TYPE_UNSIGNED (type
))
3575 val
= integer_zero_node
;
3579 val
= compare_range_with_value (LE_EXPR
, vr
,
3583 val
= compare_range_with_value (GE_EXPR
, vr
,
3588 if (integer_zerop (val
))
3589 val
= integer_one_node
;
3590 else if (integer_onep (val
))
3591 val
= integer_zero_node
;
3596 && (integer_onep (val
) || integer_zerop (val
)))
3600 if (integer_onep (val
))
3601 t
= build1 (NEGATE_EXPR
, TREE_TYPE (op
), op
);
3605 TREE_OPERAND (stmt
, 1) = t
;
3612 /* TODO. Simplify conditionals. */
3618 /* Traverse all the blocks folding conditionals with known ranges. */
3624 prop_value_t
*single_val_range
;
3625 bool do_value_subst_p
;
3629 fprintf (dump_file
, "\nValue ranges after VRP:\n\n");
3630 dump_all_value_ranges (dump_file
);
3631 fprintf (dump_file
, "\n");
3634 /* We may have ended with ranges that have exactly one value. Those
3635 values can be substituted as any other copy/const propagated
3636 value using substitute_and_fold. */
3637 single_val_range
= xmalloc (num_ssa_names
* sizeof (*single_val_range
));
3638 memset (single_val_range
, 0, num_ssa_names
* sizeof (*single_val_range
));
3640 do_value_subst_p
= false;
3641 for (i
= 0; i
< num_ssa_names
; i
++)
3643 && vr_value
[i
]->type
== VR_RANGE
3644 && vr_value
[i
]->min
== vr_value
[i
]->max
)
3646 single_val_range
[i
].value
= vr_value
[i
]->min
;
3647 do_value_subst_p
= true;
3650 if (!do_value_subst_p
)
3652 /* We found no single-valued ranges, don't waste time trying to
3653 do single value substitution in substitute_and_fold. */
3654 free (single_val_range
);
3655 single_val_range
= NULL
;
3658 substitute_and_fold (single_val_range
, true);
3660 /* One could argue all simplifications should be done here
3661 rather than using substitute_and_fold since this code
3662 is going to have to perform a complete walk through the
3664 simplify_using_ranges ();
3666 /* Free allocated memory. */
3667 for (i
= 0; i
< num_ssa_names
; i
++)
3670 BITMAP_FREE (vr_value
[i
]->equiv
);
3674 free (single_val_range
);
3679 /* Main entry point to VRP (Value Range Propagation). This pass is
3680 loosely based on J. R. C. Patterson, ``Accurate Static Branch
3681 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
3682 Programming Language Design and Implementation, pp. 67-78, 1995.
3683 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
3685 This is essentially an SSA-CCP pass modified to deal with ranges
3686 instead of constants.
3688 While propagating ranges, we may find that two or more SSA name
3689 have equivalent, though distinct ranges. For instance,
3692 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
3694 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
3698 In the code above, pointer p_5 has range [q_2, q_2], but from the
3699 code we can also determine that p_5 cannot be NULL and, if q_2 had
3700 a non-varying range, p_5's range should also be compatible with it.
3702 These equivalences are created by two expressions: ASSERT_EXPR and
3703 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
3704 result of another assertion, then we can use the fact that p_5 and
3705 p_4 are equivalent when evaluating p_5's range.
3707 Together with value ranges, we also propagate these equivalences
3708 between names so that we can take advantage of information from
3709 multiple ranges when doing final replacement. Note that this
3710 equivalency relation is transitive but not symmetric.
3712 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
3713 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
3714 in contexts where that assertion does not hold (e.g., in line 6).
3716 TODO, the main difference between this pass and Patterson's is that
3717 we do not propagate edge probabilities. We only compute whether
3718 edges can be taken or not. That is, instead of having a spectrum
3719 of jump probabilities between 0 and 1, we only deal with 0, 1 and
3720 DON'T KNOW. In the future, it may be worthwhile to propagate
3721 probabilities to aid branch prediction. */
3726 insert_range_assertions ();
3728 cfg_loops
= loop_optimizer_init (NULL
);
3730 scev_initialize (cfg_loops
);
3733 ssa_propagate (vrp_visit_stmt
, vrp_visit_phi_node
);
3739 loop_optimizer_finalize (cfg_loops
, NULL
);
3740 current_loops
= NULL
;
3743 remove_range_assertions ();
3749 return flag_tree_vrp
!= 0;
3752 struct tree_opt_pass pass_vrp
=
3755 gate_vrp
, /* gate */
3756 execute_vrp
, /* execute */
3759 0, /* static_pass_number */
3760 TV_TREE_VRP
, /* tv_id */
3761 PROP_ssa
| PROP_alias
, /* properties_required */
3762 0, /* properties_provided */
3763 0, /* properties_destroyed */
3764 0, /* todo_flags_start */
3769 | TODO_update_ssa
, /* todo_flags_finish */