1 /* Support routines for Value Range Propagation (VRP).
2 Copyright (C) 2005, 2006, 2007 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 3, 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 COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
28 #include "basic-block.h"
29 #include "tree-flow.h"
30 #include "tree-pass.h"
31 #include "tree-dump.h"
33 #include "diagnostic.h"
37 #include "tree-scalar-evolution.h"
38 #include "tree-ssa-propagate.h"
39 #include "tree-chrec.h"
41 /* Set of SSA names found during the dominator traversal of a
42 sub-graph in find_assert_locations. */
43 static sbitmap found_in_subgraph
;
45 /* Local functions. */
46 static int compare_values (tree val1
, tree val2
);
47 static int compare_values_warnv (tree val1
, tree val2
, bool *);
48 static tree
vrp_evaluate_conditional_warnv (tree
, bool, bool *);
50 /* Location information for ASSERT_EXPRs. Each instance of this
51 structure describes an ASSERT_EXPR for an SSA name. Since a single
52 SSA name may have more than one assertion associated with it, these
53 locations are kept in a linked list attached to the corresponding
57 /* Basic block where the assertion would be inserted. */
60 /* Some assertions need to be inserted on an edge (e.g., assertions
61 generated by COND_EXPRs). In those cases, BB will be NULL. */
64 /* Pointer to the statement that generated this assertion. */
65 block_stmt_iterator si
;
67 /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */
68 enum tree_code comp_code
;
70 /* Value being compared against. */
73 /* Next node in the linked list. */
74 struct assert_locus_d
*next
;
77 typedef struct assert_locus_d
*assert_locus_t
;
79 /* If bit I is present, it means that SSA name N_i has a list of
80 assertions that should be inserted in the IL. */
81 static bitmap need_assert_for
;
83 /* Array of locations lists where to insert assertions. ASSERTS_FOR[I]
84 holds a list of ASSERT_LOCUS_T nodes that describe where
85 ASSERT_EXPRs for SSA name N_I should be inserted. */
86 static assert_locus_t
*asserts_for
;
88 /* Set of blocks visited in find_assert_locations. Used to avoid
89 visiting the same block more than once. */
90 static sbitmap blocks_visited
;
92 /* Value range array. After propagation, VR_VALUE[I] holds the range
93 of values that SSA name N_I may take. */
94 static value_range_t
**vr_value
;
97 /* Return whether TYPE should use an overflow infinity distinct from
98 TYPE_{MIN,MAX}_VALUE. We use an overflow infinity value to
99 represent a signed overflow during VRP computations. An infinity
100 is distinct from a half-range, which will go from some number to
101 TYPE_{MIN,MAX}_VALUE. */
104 needs_overflow_infinity (tree type
)
106 return INTEGRAL_TYPE_P (type
) && !TYPE_OVERFLOW_WRAPS (type
);
109 /* Return whether TYPE can support our overflow infinity
110 representation: we use the TREE_OVERFLOW flag, which only exists
111 for constants. If TYPE doesn't support this, we don't optimize
112 cases which would require signed overflow--we drop them to
116 supports_overflow_infinity (tree type
)
118 #ifdef ENABLE_CHECKING
119 gcc_assert (needs_overflow_infinity (type
));
121 return (TYPE_MIN_VALUE (type
) != NULL_TREE
122 && CONSTANT_CLASS_P (TYPE_MIN_VALUE (type
))
123 && TYPE_MAX_VALUE (type
) != NULL_TREE
124 && CONSTANT_CLASS_P (TYPE_MAX_VALUE (type
)));
127 /* VAL is the maximum or minimum value of a type. Return a
128 corresponding overflow infinity. */
131 make_overflow_infinity (tree val
)
133 #ifdef ENABLE_CHECKING
134 gcc_assert (val
!= NULL_TREE
&& CONSTANT_CLASS_P (val
));
136 val
= copy_node (val
);
137 TREE_OVERFLOW (val
) = 1;
141 /* Return a negative overflow infinity for TYPE. */
144 negative_overflow_infinity (tree type
)
146 #ifdef ENABLE_CHECKING
147 gcc_assert (supports_overflow_infinity (type
));
149 return make_overflow_infinity (TYPE_MIN_VALUE (type
));
152 /* Return a positive overflow infinity for TYPE. */
155 positive_overflow_infinity (tree type
)
157 #ifdef ENABLE_CHECKING
158 gcc_assert (supports_overflow_infinity (type
));
160 return make_overflow_infinity (TYPE_MAX_VALUE (type
));
163 /* Return whether VAL is a negative overflow infinity. */
166 is_negative_overflow_infinity (tree val
)
168 return (needs_overflow_infinity (TREE_TYPE (val
))
169 && CONSTANT_CLASS_P (val
)
170 && TREE_OVERFLOW (val
)
171 && operand_equal_p (val
, TYPE_MIN_VALUE (TREE_TYPE (val
)), 0));
174 /* Return whether VAL is a positive overflow infinity. */
177 is_positive_overflow_infinity (tree val
)
179 return (needs_overflow_infinity (TREE_TYPE (val
))
180 && CONSTANT_CLASS_P (val
)
181 && TREE_OVERFLOW (val
)
182 && operand_equal_p (val
, TYPE_MAX_VALUE (TREE_TYPE (val
)), 0));
185 /* Return whether VAL is a positive or negative overflow infinity. */
188 is_overflow_infinity (tree val
)
190 return (needs_overflow_infinity (TREE_TYPE (val
))
191 && CONSTANT_CLASS_P (val
)
192 && TREE_OVERFLOW (val
)
193 && (operand_equal_p (val
, TYPE_MAX_VALUE (TREE_TYPE (val
)), 0)
194 || operand_equal_p (val
, TYPE_MIN_VALUE (TREE_TYPE (val
)), 0)));
197 /* If VAL is now an overflow infinity, return VAL. Otherwise, return
198 the same value with TREE_OVERFLOW clear. This can be used to avoid
199 confusing a regular value with an overflow value. */
202 avoid_overflow_infinity (tree val
)
204 if (!is_overflow_infinity (val
))
207 if (operand_equal_p (val
, TYPE_MAX_VALUE (TREE_TYPE (val
)), 0))
208 return TYPE_MAX_VALUE (TREE_TYPE (val
));
211 #ifdef ENABLE_CHECKING
212 gcc_assert (operand_equal_p (val
, TYPE_MIN_VALUE (TREE_TYPE (val
)), 0));
214 return TYPE_MIN_VALUE (TREE_TYPE (val
));
219 /* Return whether VAL is equal to the maximum value of its type. This
220 will be true for a positive overflow infinity. We can't do a
221 simple equality comparison with TYPE_MAX_VALUE because C typedefs
222 and Ada subtypes can produce types whose TYPE_MAX_VALUE is not ==
223 to the integer constant with the same value in the type. */
226 vrp_val_is_max (tree val
)
228 tree type_max
= TYPE_MAX_VALUE (TREE_TYPE (val
));
230 return (val
== type_max
231 || (type_max
!= NULL_TREE
232 && operand_equal_p (val
, type_max
, 0)));
235 /* Return whether VAL is equal to the minimum value of its type. This
236 will be true for a negative overflow infinity. */
239 vrp_val_is_min (tree val
)
241 tree type_min
= TYPE_MIN_VALUE (TREE_TYPE (val
));
243 return (val
== type_min
244 || (type_min
!= NULL_TREE
245 && operand_equal_p (val
, type_min
, 0)));
249 /* Return true if ARG is marked with the nonnull attribute in the
250 current function signature. */
253 nonnull_arg_p (tree arg
)
255 tree t
, attrs
, fntype
;
256 unsigned HOST_WIDE_INT arg_num
;
258 gcc_assert (TREE_CODE (arg
) == PARM_DECL
&& POINTER_TYPE_P (TREE_TYPE (arg
)));
260 /* The static chain decl is always non null. */
261 if (arg
== cfun
->static_chain_decl
)
264 fntype
= TREE_TYPE (current_function_decl
);
265 attrs
= lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype
));
267 /* If "nonnull" wasn't specified, we know nothing about the argument. */
268 if (attrs
== NULL_TREE
)
271 /* If "nonnull" applies to all the arguments, then ARG is non-null. */
272 if (TREE_VALUE (attrs
) == NULL_TREE
)
275 /* Get the position number for ARG in the function signature. */
276 for (arg_num
= 1, t
= DECL_ARGUMENTS (current_function_decl
);
278 t
= TREE_CHAIN (t
), arg_num
++)
284 gcc_assert (t
== arg
);
286 /* Now see if ARG_NUM is mentioned in the nonnull list. */
287 for (t
= TREE_VALUE (attrs
); t
; t
= TREE_CHAIN (t
))
289 if (compare_tree_int (TREE_VALUE (t
), arg_num
) == 0)
297 /* Set value range VR to {T, MIN, MAX, EQUIV}. */
300 set_value_range (value_range_t
*vr
, enum value_range_type t
, tree min
,
301 tree max
, bitmap equiv
)
303 #if defined ENABLE_CHECKING
304 /* Check the validity of the range. */
305 if (t
== VR_RANGE
|| t
== VR_ANTI_RANGE
)
309 gcc_assert (min
&& max
);
311 if (INTEGRAL_TYPE_P (TREE_TYPE (min
)) && t
== VR_ANTI_RANGE
)
312 gcc_assert (!vrp_val_is_min (min
) || !vrp_val_is_max (max
));
314 cmp
= compare_values (min
, max
);
315 gcc_assert (cmp
== 0 || cmp
== -1 || cmp
== -2);
317 if (needs_overflow_infinity (TREE_TYPE (min
)))
318 gcc_assert (!is_overflow_infinity (min
)
319 || !is_overflow_infinity (max
));
322 if (t
== VR_UNDEFINED
|| t
== VR_VARYING
)
323 gcc_assert (min
== NULL_TREE
&& max
== NULL_TREE
);
325 if (t
== VR_UNDEFINED
|| t
== VR_VARYING
)
326 gcc_assert (equiv
== NULL
|| bitmap_empty_p (equiv
));
333 /* Since updating the equivalence set involves deep copying the
334 bitmaps, only do it if absolutely necessary. */
335 if (vr
->equiv
== NULL
)
336 vr
->equiv
= BITMAP_ALLOC (NULL
);
338 if (equiv
!= vr
->equiv
)
340 if (equiv
&& !bitmap_empty_p (equiv
))
341 bitmap_copy (vr
->equiv
, equiv
);
343 bitmap_clear (vr
->equiv
);
348 /* Copy value range FROM into value range TO. */
351 copy_value_range (value_range_t
*to
, value_range_t
*from
)
353 set_value_range (to
, from
->type
, from
->min
, from
->max
, from
->equiv
);
357 /* Set value range VR to VR_VARYING. */
360 set_value_range_to_varying (value_range_t
*vr
)
362 vr
->type
= VR_VARYING
;
363 vr
->min
= vr
->max
= NULL_TREE
;
365 bitmap_clear (vr
->equiv
);
368 /* Set value range VR to a single value. This function is only called
369 with values we get from statements, and exists to clear the
370 TREE_OVERFLOW flag so that we don't think we have an overflow
371 infinity when we shouldn't. */
374 set_value_range_to_value (value_range_t
*vr
, tree val
, bitmap equiv
)
376 gcc_assert (is_gimple_min_invariant (val
));
377 val
= avoid_overflow_infinity (val
);
378 set_value_range (vr
, VR_RANGE
, val
, val
, equiv
);
381 /* Set value range VR to a non-negative range of type TYPE.
382 OVERFLOW_INFINITY indicates whether to use a overflow infinity
383 rather than TYPE_MAX_VALUE; this should be true if we determine
384 that the range is nonnegative based on the assumption that signed
385 overflow does not occur. */
388 set_value_range_to_nonnegative (value_range_t
*vr
, tree type
,
389 bool overflow_infinity
)
393 if (overflow_infinity
&& !supports_overflow_infinity (type
))
395 set_value_range_to_varying (vr
);
399 zero
= build_int_cst (type
, 0);
400 set_value_range (vr
, VR_RANGE
, zero
,
402 ? positive_overflow_infinity (type
)
403 : TYPE_MAX_VALUE (type
)),
407 /* Set value range VR to a non-NULL range of type TYPE. */
410 set_value_range_to_nonnull (value_range_t
*vr
, tree type
)
412 tree zero
= build_int_cst (type
, 0);
413 set_value_range (vr
, VR_ANTI_RANGE
, zero
, zero
, vr
->equiv
);
417 /* Set value range VR to a NULL range of type TYPE. */
420 set_value_range_to_null (value_range_t
*vr
, tree type
)
422 set_value_range_to_value (vr
, build_int_cst (type
, 0), vr
->equiv
);
426 /* Set value range VR to VR_UNDEFINED. */
429 set_value_range_to_undefined (value_range_t
*vr
)
431 vr
->type
= VR_UNDEFINED
;
432 vr
->min
= vr
->max
= NULL_TREE
;
434 bitmap_clear (vr
->equiv
);
438 /* Return value range information for VAR.
440 If we have no values ranges recorded (ie, VRP is not running), then
441 return NULL. Otherwise create an empty range if none existed for VAR. */
443 static value_range_t
*
444 get_value_range (tree var
)
448 unsigned ver
= SSA_NAME_VERSION (var
);
450 /* If we have no recorded ranges, then return NULL. */
458 /* Create a default value range. */
459 vr_value
[ver
] = vr
= XNEW (value_range_t
);
460 memset (vr
, 0, sizeof (*vr
));
462 /* Allocate an equivalence set. */
463 vr
->equiv
= BITMAP_ALLOC (NULL
);
465 /* If VAR is a default definition, the variable can take any value
467 sym
= SSA_NAME_VAR (var
);
468 if (var
== default_def (sym
))
470 /* Try to use the "nonnull" attribute to create ~[0, 0]
471 anti-ranges for pointers. Note that this is only valid with
472 default definitions of PARM_DECLs. */
473 if (TREE_CODE (sym
) == PARM_DECL
474 && POINTER_TYPE_P (TREE_TYPE (sym
))
475 && nonnull_arg_p (sym
))
476 set_value_range_to_nonnull (vr
, TREE_TYPE (sym
));
478 set_value_range_to_varying (vr
);
484 /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */
487 vrp_operand_equal_p (tree val1
, tree val2
)
491 if (!val1
|| !val2
|| !operand_equal_p (val1
, val2
, 0))
493 if (is_overflow_infinity (val1
))
494 return is_overflow_infinity (val2
);
498 /* Return true, if the bitmaps B1 and B2 are equal. */
501 vrp_bitmap_equal_p (bitmap b1
, bitmap b2
)
505 && bitmap_equal_p (b1
, b2
)));
508 /* Update the value range and equivalence set for variable VAR to
509 NEW_VR. Return true if NEW_VR is different from VAR's previous
512 NOTE: This function assumes that NEW_VR is a temporary value range
513 object created for the sole purpose of updating VAR's range. The
514 storage used by the equivalence set from NEW_VR will be freed by
515 this function. Do not call update_value_range when NEW_VR
516 is the range object associated with another SSA name. */
519 update_value_range (tree var
, value_range_t
*new_vr
)
521 value_range_t
*old_vr
;
524 /* Update the value range, if necessary. */
525 old_vr
= get_value_range (var
);
526 is_new
= old_vr
->type
!= new_vr
->type
527 || !vrp_operand_equal_p (old_vr
->min
, new_vr
->min
)
528 || !vrp_operand_equal_p (old_vr
->max
, new_vr
->max
)
529 || !vrp_bitmap_equal_p (old_vr
->equiv
, new_vr
->equiv
);
532 set_value_range (old_vr
, new_vr
->type
, new_vr
->min
, new_vr
->max
,
535 BITMAP_FREE (new_vr
->equiv
);
536 new_vr
->equiv
= NULL
;
542 /* Add VAR and VAR's equivalence set to EQUIV. */
545 add_equivalence (bitmap equiv
, tree var
)
547 unsigned ver
= SSA_NAME_VERSION (var
);
548 value_range_t
*vr
= vr_value
[ver
];
550 bitmap_set_bit (equiv
, ver
);
552 bitmap_ior_into (equiv
, vr
->equiv
);
556 /* Return true if VR is ~[0, 0]. */
559 range_is_nonnull (value_range_t
*vr
)
561 return vr
->type
== VR_ANTI_RANGE
562 && integer_zerop (vr
->min
)
563 && integer_zerop (vr
->max
);
567 /* Return true if VR is [0, 0]. */
570 range_is_null (value_range_t
*vr
)
572 return vr
->type
== VR_RANGE
573 && integer_zerop (vr
->min
)
574 && integer_zerop (vr
->max
);
578 /* Return true if value range VR involves at least one symbol. */
581 symbolic_range_p (value_range_t
*vr
)
583 return (!is_gimple_min_invariant (vr
->min
)
584 || !is_gimple_min_invariant (vr
->max
));
587 /* Return true if value range VR uses a overflow infinity. */
590 overflow_infinity_range_p (value_range_t
*vr
)
592 return (vr
->type
== VR_RANGE
593 && (is_overflow_infinity (vr
->min
)
594 || is_overflow_infinity (vr
->max
)));
597 /* Return false if we can not make a valid comparison based on VR;
598 this will be the case if it uses an overflow infinity and overflow
599 is not undefined (i.e., -fno-strict-overflow is in effect).
600 Otherwise return true, and set *STRICT_OVERFLOW_P to true if VR
601 uses an overflow infinity. */
604 usable_range_p (value_range_t
*vr
, bool *strict_overflow_p
)
606 gcc_assert (vr
->type
== VR_RANGE
);
607 if (is_overflow_infinity (vr
->min
))
609 *strict_overflow_p
= true;
610 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr
->min
)))
613 if (is_overflow_infinity (vr
->max
))
615 *strict_overflow_p
= true;
616 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr
->max
)))
623 /* Like tree_expr_nonnegative_warnv_p, but this function uses value
624 ranges obtained so far. */
627 vrp_expr_computes_nonnegative (tree expr
, bool *strict_overflow_p
)
629 return tree_expr_nonnegative_warnv_p (expr
, strict_overflow_p
);
632 /* Like tree_expr_nonzero_warnv_p, but this function uses value ranges
636 vrp_expr_computes_nonzero (tree expr
, bool *strict_overflow_p
)
638 if (tree_expr_nonzero_warnv_p (expr
, strict_overflow_p
))
641 /* If we have an expression of the form &X->a, then the expression
642 is nonnull if X is nonnull. */
643 if (TREE_CODE (expr
) == ADDR_EXPR
)
645 tree base
= get_base_address (TREE_OPERAND (expr
, 0));
647 if (base
!= NULL_TREE
648 && TREE_CODE (base
) == INDIRECT_REF
649 && TREE_CODE (TREE_OPERAND (base
, 0)) == SSA_NAME
)
651 value_range_t
*vr
= get_value_range (TREE_OPERAND (base
, 0));
652 if (range_is_nonnull (vr
))
660 /* Returns true if EXPR is a valid value (as expected by compare_values) --
661 a gimple invariant, or SSA_NAME +- CST. */
664 valid_value_p (tree expr
)
666 if (TREE_CODE (expr
) == SSA_NAME
)
669 if (TREE_CODE (expr
) == PLUS_EXPR
670 || TREE_CODE (expr
) == MINUS_EXPR
)
671 return (TREE_CODE (TREE_OPERAND (expr
, 0)) == SSA_NAME
672 && TREE_CODE (TREE_OPERAND (expr
, 1)) == INTEGER_CST
);
674 return is_gimple_min_invariant (expr
);
677 /* Compare two values VAL1 and VAL2. Return
679 -2 if VAL1 and VAL2 cannot be compared at compile-time,
682 +1 if VAL1 > VAL2, and
685 This is similar to tree_int_cst_compare but supports pointer values
686 and values that cannot be compared at compile time.
688 If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to
689 true if the return value is only valid if we assume that signed
690 overflow is undefined. */
693 compare_values_warnv (tree val1
, tree val2
, bool *strict_overflow_p
)
698 /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
700 gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1
))
701 == POINTER_TYPE_P (TREE_TYPE (val2
)));
703 if ((TREE_CODE (val1
) == SSA_NAME
704 || TREE_CODE (val1
) == PLUS_EXPR
705 || TREE_CODE (val1
) == MINUS_EXPR
)
706 && (TREE_CODE (val2
) == SSA_NAME
707 || TREE_CODE (val2
) == PLUS_EXPR
708 || TREE_CODE (val2
) == MINUS_EXPR
))
711 enum tree_code code1
, code2
;
713 /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME',
714 return -1 or +1 accordingly. If VAL1 and VAL2 don't use the
715 same name, return -2. */
716 if (TREE_CODE (val1
) == SSA_NAME
)
724 code1
= TREE_CODE (val1
);
725 n1
= TREE_OPERAND (val1
, 0);
726 c1
= TREE_OPERAND (val1
, 1);
727 if (tree_int_cst_sgn (c1
) == -1)
729 if (is_negative_overflow_infinity (c1
))
731 c1
= fold_unary_to_constant (NEGATE_EXPR
, TREE_TYPE (c1
), c1
);
734 code1
= code1
== MINUS_EXPR
? PLUS_EXPR
: MINUS_EXPR
;
738 if (TREE_CODE (val2
) == SSA_NAME
)
746 code2
= TREE_CODE (val2
);
747 n2
= TREE_OPERAND (val2
, 0);
748 c2
= TREE_OPERAND (val2
, 1);
749 if (tree_int_cst_sgn (c2
) == -1)
751 if (is_negative_overflow_infinity (c2
))
753 c2
= fold_unary_to_constant (NEGATE_EXPR
, TREE_TYPE (c2
), c2
);
756 code2
= code2
== MINUS_EXPR
? PLUS_EXPR
: MINUS_EXPR
;
760 /* Both values must use the same name. */
764 if (code1
== SSA_NAME
765 && code2
== SSA_NAME
)
769 /* If overflow is defined we cannot simplify more. */
770 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1
)))
773 if (strict_overflow_p
!= NULL
774 && (code1
== SSA_NAME
|| !TREE_NO_WARNING (val1
))
775 && (code2
== SSA_NAME
|| !TREE_NO_WARNING (val2
)))
776 *strict_overflow_p
= true;
778 if (code1
== SSA_NAME
)
780 if (code2
== PLUS_EXPR
)
781 /* NAME < NAME + CST */
783 else if (code2
== MINUS_EXPR
)
784 /* NAME > NAME - CST */
787 else if (code1
== PLUS_EXPR
)
789 if (code2
== SSA_NAME
)
790 /* NAME + CST > NAME */
792 else if (code2
== PLUS_EXPR
)
793 /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */
794 return compare_values_warnv (c1
, c2
, strict_overflow_p
);
795 else if (code2
== MINUS_EXPR
)
796 /* NAME + CST1 > NAME - CST2 */
799 else if (code1
== MINUS_EXPR
)
801 if (code2
== SSA_NAME
)
802 /* NAME - CST < NAME */
804 else if (code2
== PLUS_EXPR
)
805 /* NAME - CST1 < NAME + CST2 */
807 else if (code2
== MINUS_EXPR
)
808 /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that
809 C1 and C2 are swapped in the call to compare_values. */
810 return compare_values_warnv (c2
, c1
, strict_overflow_p
);
816 /* We cannot compare non-constants. */
817 if (!is_gimple_min_invariant (val1
) || !is_gimple_min_invariant (val2
))
820 if (!POINTER_TYPE_P (TREE_TYPE (val1
)))
822 /* We cannot compare overflowed values, except for overflow
824 if (TREE_OVERFLOW (val1
) || TREE_OVERFLOW (val2
))
826 if (strict_overflow_p
!= NULL
)
827 *strict_overflow_p
= true;
828 if (is_negative_overflow_infinity (val1
))
829 return is_negative_overflow_infinity (val2
) ? 0 : -1;
830 else if (is_negative_overflow_infinity (val2
))
832 else if (is_positive_overflow_infinity (val1
))
833 return is_positive_overflow_infinity (val2
) ? 0 : 1;
834 else if (is_positive_overflow_infinity (val2
))
839 return tree_int_cst_compare (val1
, val2
);
845 /* First see if VAL1 and VAL2 are not the same. */
846 if (val1
== val2
|| operand_equal_p (val1
, val2
, 0))
849 /* If VAL1 is a lower address than VAL2, return -1. */
850 t
= fold_binary (LT_EXPR
, boolean_type_node
, val1
, val2
);
851 if (t
== boolean_true_node
)
854 /* If VAL1 is a higher address than VAL2, return +1. */
855 t
= fold_binary (GT_EXPR
, boolean_type_node
, val1
, val2
);
856 if (t
== boolean_true_node
)
859 /* If VAL1 is different than VAL2, return +2. */
860 t
= fold_binary (NE_EXPR
, boolean_type_node
, val1
, val2
);
861 if (t
== boolean_true_node
)
868 /* Compare values like compare_values_warnv, but treat comparisons of
869 nonconstants which rely on undefined overflow as incomparable. */
872 compare_values (tree val1
, tree val2
)
878 ret
= compare_values_warnv (val1
, val2
, &sop
);
880 && (!is_gimple_min_invariant (val1
) || !is_gimple_min_invariant (val2
)))
886 /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX),
887 0 if VAL is not inside VR,
888 -2 if we cannot tell either way.
890 FIXME, the current semantics of this functions are a bit quirky
891 when taken in the context of VRP. In here we do not care
892 about VR's type. If VR is the anti-range ~[3, 5] the call
893 value_inside_range (4, VR) will return 1.
895 This is counter-intuitive in a strict sense, but the callers
896 currently expect this. They are calling the function
897 merely to determine whether VR->MIN <= VAL <= VR->MAX. The
898 callers are applying the VR_RANGE/VR_ANTI_RANGE semantics
901 This also applies to value_ranges_intersect_p and
902 range_includes_zero_p. The semantics of VR_RANGE and
903 VR_ANTI_RANGE should be encoded here, but that also means
904 adapting the users of these functions to the new semantics. */
907 value_inside_range (tree val
, value_range_t
*vr
)
911 fold_defer_overflow_warnings ();
913 cmp1
= fold_binary_to_constant (GE_EXPR
, boolean_type_node
, val
, vr
->min
);
916 fold_undefer_and_ignore_overflow_warnings ();
920 cmp2
= fold_binary_to_constant (LE_EXPR
, boolean_type_node
, val
, vr
->max
);
922 fold_undefer_and_ignore_overflow_warnings ();
927 return cmp1
== boolean_true_node
&& cmp2
== boolean_true_node
;
931 /* Return true if value ranges VR0 and VR1 have a non-empty
935 value_ranges_intersect_p (value_range_t
*vr0
, value_range_t
*vr1
)
937 return (value_inside_range (vr1
->min
, vr0
) == 1
938 || value_inside_range (vr1
->max
, vr0
) == 1
939 || value_inside_range (vr0
->min
, vr1
) == 1
940 || value_inside_range (vr0
->max
, vr1
) == 1);
944 /* Return true if VR includes the value zero, false otherwise. FIXME,
945 currently this will return false for an anti-range like ~[-4, 3].
946 This will be wrong when the semantics of value_inside_range are
947 modified (currently the users of this function expect these
951 range_includes_zero_p (value_range_t
*vr
)
955 gcc_assert (vr
->type
!= VR_UNDEFINED
956 && vr
->type
!= VR_VARYING
957 && !symbolic_range_p (vr
));
959 zero
= build_int_cst (TREE_TYPE (vr
->min
), 0);
960 return (value_inside_range (zero
, vr
) == 1);
963 /* Return true if T, an SSA_NAME, is known to be nonnegative. Return
964 false otherwise or if no value range information is available. */
967 ssa_name_nonnegative_p (tree t
)
969 value_range_t
*vr
= get_value_range (t
);
974 /* Testing for VR_ANTI_RANGE is not useful here as any anti-range
975 which would return a useful value should be encoded as a VR_RANGE. */
976 if (vr
->type
== VR_RANGE
)
978 int result
= compare_values (vr
->min
, integer_zero_node
);
980 return (result
== 0 || result
== 1);
985 /* Return true if T, an SSA_NAME, is known to be nonzero. Return
986 false otherwise or if no value range information is available. */
989 ssa_name_nonzero_p (tree t
)
991 value_range_t
*vr
= get_value_range (t
);
996 /* A VR_RANGE which does not include zero is a nonzero value. */
997 if (vr
->type
== VR_RANGE
&& !symbolic_range_p (vr
))
998 return ! range_includes_zero_p (vr
);
1000 /* A VR_ANTI_RANGE which does include zero is a nonzero value. */
1001 if (vr
->type
== VR_ANTI_RANGE
&& !symbolic_range_p (vr
))
1002 return range_includes_zero_p (vr
);
1008 /* Extract value range information from an ASSERT_EXPR EXPR and store
1012 extract_range_from_assert (value_range_t
*vr_p
, tree expr
)
1014 tree var
, cond
, limit
, min
, max
, type
;
1015 value_range_t
*var_vr
, *limit_vr
;
1016 enum tree_code cond_code
;
1018 var
= ASSERT_EXPR_VAR (expr
);
1019 cond
= ASSERT_EXPR_COND (expr
);
1021 gcc_assert (COMPARISON_CLASS_P (cond
));
1023 /* Find VAR in the ASSERT_EXPR conditional. */
1024 if (var
== TREE_OPERAND (cond
, 0))
1026 /* If the predicate is of the form VAR COMP LIMIT, then we just
1027 take LIMIT from the RHS and use the same comparison code. */
1028 limit
= TREE_OPERAND (cond
, 1);
1029 cond_code
= TREE_CODE (cond
);
1033 /* If the predicate is of the form LIMIT COMP VAR, then we need
1034 to flip around the comparison code to create the proper range
1036 limit
= TREE_OPERAND (cond
, 0);
1037 cond_code
= swap_tree_comparison (TREE_CODE (cond
));
1040 limit
= avoid_overflow_infinity (limit
);
1042 type
= TREE_TYPE (limit
);
1043 gcc_assert (limit
!= var
);
1045 /* For pointer arithmetic, we only keep track of pointer equality
1047 if (POINTER_TYPE_P (type
) && cond_code
!= NE_EXPR
&& cond_code
!= EQ_EXPR
)
1049 set_value_range_to_varying (vr_p
);
1053 /* If LIMIT is another SSA name and LIMIT has a range of its own,
1054 try to use LIMIT's range to avoid creating symbolic ranges
1056 limit_vr
= (TREE_CODE (limit
) == SSA_NAME
) ? get_value_range (limit
) : NULL
;
1058 /* LIMIT's range is only interesting if it has any useful information. */
1060 && (limit_vr
->type
== VR_UNDEFINED
1061 || limit_vr
->type
== VR_VARYING
1062 || symbolic_range_p (limit_vr
)))
1065 /* Initially, the new range has the same set of equivalences of
1066 VAR's range. This will be revised before returning the final
1067 value. Since assertions may be chained via mutually exclusive
1068 predicates, we will need to trim the set of equivalences before
1070 gcc_assert (vr_p
->equiv
== NULL
);
1071 vr_p
->equiv
= BITMAP_ALLOC (NULL
);
1072 add_equivalence (vr_p
->equiv
, var
);
1074 /* Extract a new range based on the asserted comparison for VAR and
1075 LIMIT's value range. Notice that if LIMIT has an anti-range, we
1076 will only use it for equality comparisons (EQ_EXPR). For any
1077 other kind of assertion, we cannot derive a range from LIMIT's
1078 anti-range that can be used to describe the new range. For
1079 instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
1080 then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
1081 no single range for x_2 that could describe LE_EXPR, so we might
1082 as well build the range [b_4, +INF] for it. */
1083 if (cond_code
== EQ_EXPR
)
1085 enum value_range_type range_type
;
1089 range_type
= limit_vr
->type
;
1090 min
= limit_vr
->min
;
1091 max
= limit_vr
->max
;
1095 range_type
= VR_RANGE
;
1100 set_value_range (vr_p
, range_type
, min
, max
, vr_p
->equiv
);
1102 /* When asserting the equality VAR == LIMIT and LIMIT is another
1103 SSA name, the new range will also inherit the equivalence set
1105 if (TREE_CODE (limit
) == SSA_NAME
)
1106 add_equivalence (vr_p
->equiv
, limit
);
1108 else if (cond_code
== NE_EXPR
)
1110 /* As described above, when LIMIT's range is an anti-range and
1111 this assertion is an inequality (NE_EXPR), then we cannot
1112 derive anything from the anti-range. For instance, if
1113 LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
1114 not imply that VAR's range is [0, 0]. So, in the case of
1115 anti-ranges, we just assert the inequality using LIMIT and
1118 If LIMIT_VR is a range, we can only use it to build a new
1119 anti-range if LIMIT_VR is a single-valued range. For
1120 instance, if LIMIT_VR is [0, 1], the predicate
1121 VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
1122 Rather, it means that for value 0 VAR should be ~[0, 0]
1123 and for value 1, VAR should be ~[1, 1]. We cannot
1124 represent these ranges.
1126 The only situation in which we can build a valid
1127 anti-range is when LIMIT_VR is a single-valued range
1128 (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
1129 build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
1131 && limit_vr
->type
== VR_RANGE
1132 && compare_values (limit_vr
->min
, limit_vr
->max
) == 0)
1134 min
= limit_vr
->min
;
1135 max
= limit_vr
->max
;
1139 /* In any other case, we cannot use LIMIT's range to build a
1140 valid anti-range. */
1144 /* If MIN and MAX cover the whole range for their type, then
1145 just use the original LIMIT. */
1146 if (INTEGRAL_TYPE_P (type
)
1147 && vrp_val_is_min (min
)
1148 && vrp_val_is_max (max
))
1151 set_value_range (vr_p
, VR_ANTI_RANGE
, min
, max
, vr_p
->equiv
);
1153 else if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
1155 min
= TYPE_MIN_VALUE (type
);
1157 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
1161 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1162 range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
1164 max
= limit_vr
->max
;
1167 /* If the maximum value forces us to be out of bounds, simply punt.
1168 It would be pointless to try and do anything more since this
1169 all should be optimized away above us. */
1170 if ((cond_code
== LT_EXPR
1171 && compare_values (max
, min
) == 0)
1172 || is_overflow_infinity (max
))
1173 set_value_range_to_varying (vr_p
);
1176 /* For LT_EXPR, we create the range [MIN, MAX - 1]. */
1177 if (cond_code
== LT_EXPR
)
1179 tree one
= build_int_cst (type
, 1);
1180 max
= fold_build2 (MINUS_EXPR
, type
, max
, one
);
1182 TREE_NO_WARNING (max
) = 1;
1185 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1188 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
1190 max
= TYPE_MAX_VALUE (type
);
1192 if (limit_vr
== NULL
|| limit_vr
->type
== VR_ANTI_RANGE
)
1196 /* If LIMIT_VR is of the form [N1, N2], we need to build the
1197 range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
1199 min
= limit_vr
->min
;
1202 /* If the minimum value forces us to be out of bounds, simply punt.
1203 It would be pointless to try and do anything more since this
1204 all should be optimized away above us. */
1205 if ((cond_code
== GT_EXPR
1206 && compare_values (min
, max
) == 0)
1207 || is_overflow_infinity (min
))
1208 set_value_range_to_varying (vr_p
);
1211 /* For GT_EXPR, we create the range [MIN + 1, MAX]. */
1212 if (cond_code
== GT_EXPR
)
1214 tree one
= build_int_cst (type
, 1);
1215 min
= fold_build2 (PLUS_EXPR
, type
, min
, one
);
1217 TREE_NO_WARNING (min
) = 1;
1220 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1226 /* If VAR already had a known range, it may happen that the new
1227 range we have computed and VAR's range are not compatible. For
1231 p_6 = ASSERT_EXPR <p_5, p_5 == NULL>;
1233 p_8 = ASSERT_EXPR <p_6, p_6 != NULL>;
1235 While the above comes from a faulty program, it will cause an ICE
1236 later because p_8 and p_6 will have incompatible ranges and at
1237 the same time will be considered equivalent. A similar situation
1241 i_6 = ASSERT_EXPR <i_5, i_5 > 10>;
1243 i_7 = ASSERT_EXPR <i_6, i_6 < 5>;
1245 Again i_6 and i_7 will have incompatible ranges. It would be
1246 pointless to try and do anything with i_7's range because
1247 anything dominated by 'if (i_5 < 5)' will be optimized away.
1248 Note, due to the wa in which simulation proceeds, the statement
1249 i_7 = ASSERT_EXPR <...> we would never be visited because the
1250 conditional 'if (i_5 < 5)' always evaluates to false. However,
1251 this extra check does not hurt and may protect against future
1252 changes to VRP that may get into a situation similar to the
1253 NULL pointer dereference example.
1255 Note that these compatibility tests are only needed when dealing
1256 with ranges or a mix of range and anti-range. If VAR_VR and VR_P
1257 are both anti-ranges, they will always be compatible, because two
1258 anti-ranges will always have a non-empty intersection. */
1260 var_vr
= get_value_range (var
);
1262 /* We may need to make adjustments when VR_P and VAR_VR are numeric
1263 ranges or anti-ranges. */
1264 if (vr_p
->type
== VR_VARYING
1265 || vr_p
->type
== VR_UNDEFINED
1266 || var_vr
->type
== VR_VARYING
1267 || var_vr
->type
== VR_UNDEFINED
1268 || symbolic_range_p (vr_p
)
1269 || symbolic_range_p (var_vr
))
1272 if (var_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_RANGE
)
1274 /* If the two ranges have a non-empty intersection, we can
1275 refine the resulting range. Since the assert expression
1276 creates an equivalency and at the same time it asserts a
1277 predicate, we can take the intersection of the two ranges to
1278 get better precision. */
1279 if (value_ranges_intersect_p (var_vr
, vr_p
))
1281 /* Use the larger of the two minimums. */
1282 if (compare_values (vr_p
->min
, var_vr
->min
) == -1)
1287 /* Use the smaller of the two maximums. */
1288 if (compare_values (vr_p
->max
, var_vr
->max
) == 1)
1293 set_value_range (vr_p
, vr_p
->type
, min
, max
, vr_p
->equiv
);
1297 /* The two ranges do not intersect, set the new range to
1298 VARYING, because we will not be able to do anything
1299 meaningful with it. */
1300 set_value_range_to_varying (vr_p
);
1303 else if ((var_vr
->type
== VR_RANGE
&& vr_p
->type
== VR_ANTI_RANGE
)
1304 || (var_vr
->type
== VR_ANTI_RANGE
&& vr_p
->type
== VR_RANGE
))
1306 /* A range and an anti-range will cancel each other only if
1307 their ends are the same. For instance, in the example above,
1308 p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible,
1309 so VR_P should be set to VR_VARYING. */
1310 if (compare_values (var_vr
->min
, vr_p
->min
) == 0
1311 && compare_values (var_vr
->max
, vr_p
->max
) == 0)
1312 set_value_range_to_varying (vr_p
);
1315 tree min
, max
, anti_min
, anti_max
, real_min
, real_max
;
1317 /* We want to compute the logical AND of the two ranges;
1318 there are three cases to consider.
1321 1. The VR_ANTI_RANGE range is completely within the
1322 VR_RANGE and the endpoints of the ranges are
1323 different. In that case the resulting range
1324 should be whichever range is more precise.
1325 Typically that will be the VR_RANGE.
1327 2. The VR_ANTI_RANGE is completely disjoint from
1328 the VR_RANGE. In this case the resulting range
1329 should be the VR_RANGE.
1331 3. There is some overlap between the VR_ANTI_RANGE
1334 3a. If the high limit of the VR_ANTI_RANGE resides
1335 within the VR_RANGE, then the result is a new
1336 VR_RANGE starting at the high limit of the
1337 the VR_ANTI_RANGE + 1 and extending to the
1338 high limit of the original VR_RANGE.
1340 3b. If the low limit of the VR_ANTI_RANGE resides
1341 within the VR_RANGE, then the result is a new
1342 VR_RANGE starting at the low limit of the original
1343 VR_RANGE and extending to the low limit of the
1344 VR_ANTI_RANGE - 1. */
1345 if (vr_p
->type
== VR_ANTI_RANGE
)
1347 anti_min
= vr_p
->min
;
1348 anti_max
= vr_p
->max
;
1349 real_min
= var_vr
->min
;
1350 real_max
= var_vr
->max
;
1354 anti_min
= var_vr
->min
;
1355 anti_max
= var_vr
->max
;
1356 real_min
= vr_p
->min
;
1357 real_max
= vr_p
->max
;
1361 /* Case 1, VR_ANTI_RANGE completely within VR_RANGE,
1362 not including any endpoints. */
1363 if (compare_values (anti_max
, real_max
) == -1
1364 && compare_values (anti_min
, real_min
) == 1)
1366 set_value_range (vr_p
, VR_RANGE
, real_min
,
1367 real_max
, vr_p
->equiv
);
1369 /* Case 2, VR_ANTI_RANGE completely disjoint from
1371 else if (compare_values (anti_min
, real_max
) == 1
1372 || compare_values (anti_max
, real_min
) == -1)
1374 set_value_range (vr_p
, VR_RANGE
, real_min
,
1375 real_max
, vr_p
->equiv
);
1377 /* Case 3a, the anti-range extends into the low
1378 part of the real range. Thus creating a new
1379 low for the real range. */
1380 else if ((compare_values (anti_max
, real_min
) == 1
1381 || compare_values (anti_max
, real_min
) == 0)
1382 && compare_values (anti_max
, real_max
) == -1)
1384 gcc_assert (!is_positive_overflow_infinity (anti_max
));
1385 if (needs_overflow_infinity (TREE_TYPE (anti_max
))
1386 && vrp_val_is_max (anti_max
))
1388 if (!supports_overflow_infinity (TREE_TYPE (var_vr
->min
)))
1390 set_value_range_to_varying (vr_p
);
1393 min
= positive_overflow_infinity (TREE_TYPE (var_vr
->min
));
1396 min
= fold_build2 (PLUS_EXPR
, TREE_TYPE (var_vr
->min
),
1398 build_int_cst (TREE_TYPE (var_vr
->min
), 1));
1400 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1402 /* Case 3b, the anti-range extends into the high
1403 part of the real range. Thus creating a new
1404 higher for the real range. */
1405 else if (compare_values (anti_min
, real_min
) == 1
1406 && (compare_values (anti_min
, real_max
) == -1
1407 || compare_values (anti_min
, real_max
) == 0))
1409 gcc_assert (!is_negative_overflow_infinity (anti_min
));
1410 if (needs_overflow_infinity (TREE_TYPE (anti_min
))
1411 && vrp_val_is_min (anti_min
))
1413 if (!supports_overflow_infinity (TREE_TYPE (var_vr
->min
)))
1415 set_value_range_to_varying (vr_p
);
1418 max
= negative_overflow_infinity (TREE_TYPE (var_vr
->min
));
1421 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (var_vr
->min
),
1423 build_int_cst (TREE_TYPE (var_vr
->min
), 1));
1425 set_value_range (vr_p
, VR_RANGE
, min
, max
, vr_p
->equiv
);
1432 /* Extract range information from SSA name VAR and store it in VR. If
1433 VAR has an interesting range, use it. Otherwise, create the
1434 range [VAR, VAR] and return it. This is useful in situations where
1435 we may have conditionals testing values of VARYING names. For
1442 Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
1446 extract_range_from_ssa_name (value_range_t
*vr
, tree var
)
1448 value_range_t
*var_vr
= get_value_range (var
);
1450 if (var_vr
->type
!= VR_UNDEFINED
&& var_vr
->type
!= VR_VARYING
)
1451 copy_value_range (vr
, var_vr
);
1453 set_value_range (vr
, VR_RANGE
, var
, var
, NULL
);
1455 add_equivalence (vr
->equiv
, var
);
1459 /* Wrapper around int_const_binop. If the operation overflows and we
1460 are not using wrapping arithmetic, then adjust the result to be
1461 -INF or +INF depending on CODE, VAL1 and VAL2. This can return
1462 NULL_TREE if we need to use an overflow infinity representation but
1463 the type does not support it. */
1466 vrp_int_const_binop (enum tree_code code
, tree val1
, tree val2
)
1470 res
= int_const_binop (code
, val1
, val2
, 0);
1472 /* If we are not using wrapping arithmetic, operate symbolically
1473 on -INF and +INF. */
1474 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1
)))
1476 int checkz
= compare_values (res
, val1
);
1477 bool overflow
= false;
1479 /* Ensure that res = val1 [+*] val2 >= val1
1480 or that res = val1 - val2 <= val1. */
1481 if ((code
== PLUS_EXPR
1482 && !(checkz
== 1 || checkz
== 0))
1483 || (code
== MINUS_EXPR
1484 && !(checkz
== 0 || checkz
== -1)))
1488 /* Checking for multiplication overflow is done by dividing the
1489 output of the multiplication by the first input of the
1490 multiplication. If the result of that division operation is
1491 not equal to the second input of the multiplication, then the
1492 multiplication overflowed. */
1493 else if (code
== MULT_EXPR
&& !integer_zerop (val1
))
1495 tree tmp
= int_const_binop (TRUNC_DIV_EXPR
,
1498 int check
= compare_values (tmp
, val2
);
1506 res
= copy_node (res
);
1507 TREE_OVERFLOW (res
) = 1;
1511 else if ((TREE_OVERFLOW (res
)
1512 && !TREE_OVERFLOW (val1
)
1513 && !TREE_OVERFLOW (val2
))
1514 || is_overflow_infinity (val1
)
1515 || is_overflow_infinity (val2
))
1517 /* If the operation overflowed but neither VAL1 nor VAL2 are
1518 overflown, return -INF or +INF depending on the operation
1519 and the combination of signs of the operands. */
1520 int sgn1
= tree_int_cst_sgn (val1
);
1521 int sgn2
= tree_int_cst_sgn (val2
);
1523 if (needs_overflow_infinity (TREE_TYPE (res
))
1524 && !supports_overflow_infinity (TREE_TYPE (res
)))
1527 /* We have to punt on adding infinities of different signs,
1528 since we can't tell what the sign of the result should be.
1529 Likewise for subtracting infinities of the same sign. */
1530 if (((code
== PLUS_EXPR
&& sgn1
!= sgn2
)
1531 || (code
== MINUS_EXPR
&& sgn1
== sgn2
))
1532 && is_overflow_infinity (val1
)
1533 && is_overflow_infinity (val2
))
1536 /* Don't try to handle division or shifting of infinities. */
1537 if ((code
== TRUNC_DIV_EXPR
1538 || code
== FLOOR_DIV_EXPR
1539 || code
== CEIL_DIV_EXPR
1540 || code
== EXACT_DIV_EXPR
1541 || code
== ROUND_DIV_EXPR
1542 || code
== RSHIFT_EXPR
)
1543 && (is_overflow_infinity (val1
)
1544 || is_overflow_infinity (val2
)))
1547 /* Notice that we only need to handle the restricted set of
1548 operations handled by extract_range_from_binary_expr.
1549 Among them, only multiplication, addition and subtraction
1550 can yield overflow without overflown operands because we
1551 are working with integral types only... except in the
1552 case VAL1 = -INF and VAL2 = -1 which overflows to +INF
1553 for division too. */
1555 /* For multiplication, the sign of the overflow is given
1556 by the comparison of the signs of the operands. */
1557 if ((code
== MULT_EXPR
&& sgn1
== sgn2
)
1558 /* For addition, the operands must be of the same sign
1559 to yield an overflow. Its sign is therefore that
1560 of one of the operands, for example the first. For
1561 infinite operands X + -INF is negative, not positive. */
1562 || (code
== PLUS_EXPR
1564 ? !is_negative_overflow_infinity (val2
)
1565 : is_positive_overflow_infinity (val2
)))
1566 /* For subtraction, non-infinite operands must be of
1567 different signs to yield an overflow. Its sign is
1568 therefore that of the first operand or the opposite of
1569 that of the second operand. A first operand of 0 counts
1570 as positive here, for the corner case 0 - (-INF), which
1571 overflows, but must yield +INF. For infinite operands 0
1572 - INF is negative, not positive. */
1573 || (code
== MINUS_EXPR
1575 ? !is_positive_overflow_infinity (val2
)
1576 : is_negative_overflow_infinity (val2
)))
1577 /* For division, the only case is -INF / -1 = +INF. */
1578 || code
== TRUNC_DIV_EXPR
1579 || code
== FLOOR_DIV_EXPR
1580 || code
== CEIL_DIV_EXPR
1581 || code
== EXACT_DIV_EXPR
1582 || code
== ROUND_DIV_EXPR
)
1583 return (needs_overflow_infinity (TREE_TYPE (res
))
1584 ? positive_overflow_infinity (TREE_TYPE (res
))
1585 : TYPE_MAX_VALUE (TREE_TYPE (res
)));
1587 return (needs_overflow_infinity (TREE_TYPE (res
))
1588 ? negative_overflow_infinity (TREE_TYPE (res
))
1589 : TYPE_MIN_VALUE (TREE_TYPE (res
)));
1596 /* Extract range information from a binary expression EXPR based on
1597 the ranges of each of its operands and the expression code. */
1600 extract_range_from_binary_expr (value_range_t
*vr
, tree expr
)
1602 enum tree_code code
= TREE_CODE (expr
);
1603 enum value_range_type type
;
1604 tree op0
, op1
, min
, max
;
1606 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1607 value_range_t vr1
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
1609 /* Not all binary expressions can be applied to ranges in a
1610 meaningful way. Handle only arithmetic operations. */
1611 if (code
!= PLUS_EXPR
1612 && code
!= MINUS_EXPR
1613 && code
!= MULT_EXPR
1614 && code
!= TRUNC_DIV_EXPR
1615 && code
!= FLOOR_DIV_EXPR
1616 && code
!= CEIL_DIV_EXPR
1617 && code
!= EXACT_DIV_EXPR
1618 && code
!= ROUND_DIV_EXPR
1621 && code
!= BIT_AND_EXPR
1622 && code
!= TRUTH_ANDIF_EXPR
1623 && code
!= TRUTH_ORIF_EXPR
1624 && code
!= TRUTH_AND_EXPR
1625 && code
!= TRUTH_OR_EXPR
)
1627 set_value_range_to_varying (vr
);
1631 /* Get value ranges for each operand. For constant operands, create
1632 a new value range with the operand to simplify processing. */
1633 op0
= TREE_OPERAND (expr
, 0);
1634 if (TREE_CODE (op0
) == SSA_NAME
)
1635 vr0
= *(get_value_range (op0
));
1636 else if (is_gimple_min_invariant (op0
))
1637 set_value_range_to_value (&vr0
, op0
, NULL
);
1639 set_value_range_to_varying (&vr0
);
1641 op1
= TREE_OPERAND (expr
, 1);
1642 if (TREE_CODE (op1
) == SSA_NAME
)
1643 vr1
= *(get_value_range (op1
));
1644 else if (is_gimple_min_invariant (op1
))
1645 set_value_range_to_value (&vr1
, op1
, NULL
);
1647 set_value_range_to_varying (&vr1
);
1649 /* If either range is UNDEFINED, so is the result. */
1650 if (vr0
.type
== VR_UNDEFINED
|| vr1
.type
== VR_UNDEFINED
)
1652 set_value_range_to_undefined (vr
);
1656 /* The type of the resulting value range defaults to VR0.TYPE. */
1659 /* Refuse to operate on VARYING ranges, ranges of different kinds
1660 and symbolic ranges. As an exception, we allow BIT_AND_EXPR
1661 because we may be able to derive a useful range even if one of
1662 the operands is VR_VARYING or symbolic range. TODO, we may be
1663 able to derive anti-ranges in some cases. */
1664 if (code
!= BIT_AND_EXPR
1665 && code
!= TRUTH_AND_EXPR
1666 && code
!= TRUTH_OR_EXPR
1667 && (vr0
.type
== VR_VARYING
1668 || vr1
.type
== VR_VARYING
1669 || vr0
.type
!= vr1
.type
1670 || symbolic_range_p (&vr0
)
1671 || symbolic_range_p (&vr1
)))
1673 set_value_range_to_varying (vr
);
1677 /* Now evaluate the expression to determine the new range. */
1678 if (POINTER_TYPE_P (TREE_TYPE (expr
))
1679 || POINTER_TYPE_P (TREE_TYPE (op0
))
1680 || POINTER_TYPE_P (TREE_TYPE (op1
)))
1682 /* For pointer types, we are really only interested in asserting
1683 whether the expression evaluates to non-NULL. FIXME, we used
1684 to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but
1685 ivopts is generating expressions with pointer multiplication
1687 if (code
== PLUS_EXPR
)
1689 if (range_is_nonnull (&vr0
) || range_is_nonnull (&vr1
))
1690 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
1691 else if (range_is_null (&vr0
) && range_is_null (&vr1
))
1692 set_value_range_to_null (vr
, TREE_TYPE (expr
));
1694 set_value_range_to_varying (vr
);
1698 /* Subtracting from a pointer, may yield 0, so just drop the
1699 resulting range to varying. */
1700 set_value_range_to_varying (vr
);
1706 /* For integer ranges, apply the operation to each end of the
1707 range and see what we end up with. */
1708 if (code
== TRUTH_ANDIF_EXPR
1709 || code
== TRUTH_ORIF_EXPR
1710 || code
== TRUTH_AND_EXPR
1711 || code
== TRUTH_OR_EXPR
)
1713 /* If one of the operands is zero, we know that the whole
1714 expression evaluates zero. */
1715 if (code
== TRUTH_AND_EXPR
1716 && ((vr0
.type
== VR_RANGE
1717 && integer_zerop (vr0
.min
)
1718 && integer_zerop (vr0
.max
))
1719 || (vr1
.type
== VR_RANGE
1720 && integer_zerop (vr1
.min
)
1721 && integer_zerop (vr1
.max
))))
1724 min
= max
= build_int_cst (TREE_TYPE (expr
), 0);
1726 /* If one of the operands is one, we know that the whole
1727 expression evaluates one. */
1728 else if (code
== TRUTH_OR_EXPR
1729 && ((vr0
.type
== VR_RANGE
1730 && integer_onep (vr0
.min
)
1731 && integer_onep (vr0
.max
))
1732 || (vr1
.type
== VR_RANGE
1733 && integer_onep (vr1
.min
)
1734 && integer_onep (vr1
.max
))))
1737 min
= max
= build_int_cst (TREE_TYPE (expr
), 1);
1739 else if (vr0
.type
!= VR_VARYING
1740 && vr1
.type
!= VR_VARYING
1741 && vr0
.type
== vr1
.type
1742 && !symbolic_range_p (&vr0
)
1743 && !overflow_infinity_range_p (&vr0
)
1744 && !symbolic_range_p (&vr1
)
1745 && !overflow_infinity_range_p (&vr1
))
1747 /* Boolean expressions cannot be folded with int_const_binop. */
1748 min
= fold_binary (code
, TREE_TYPE (expr
), vr0
.min
, vr1
.min
);
1749 max
= fold_binary (code
, TREE_TYPE (expr
), vr0
.max
, vr1
.max
);
1753 set_value_range_to_varying (vr
);
1757 else if (code
== PLUS_EXPR
1759 || code
== MAX_EXPR
)
1761 /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to
1762 VR_VARYING. It would take more effort to compute a precise
1763 range for such a case. For example, if we have op0 == 1 and
1764 op1 == -1 with their ranges both being ~[0,0], we would have
1765 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
1766 Note that we are guaranteed to have vr0.type == vr1.type at
1768 if (code
== PLUS_EXPR
&& vr0
.type
== VR_ANTI_RANGE
)
1770 set_value_range_to_varying (vr
);
1774 /* For operations that make the resulting range directly
1775 proportional to the original ranges, apply the operation to
1776 the same end of each range. */
1777 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1778 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.max
);
1780 else if (code
== MULT_EXPR
1781 || code
== TRUNC_DIV_EXPR
1782 || code
== FLOOR_DIV_EXPR
1783 || code
== CEIL_DIV_EXPR
1784 || code
== EXACT_DIV_EXPR
1785 || code
== ROUND_DIV_EXPR
)
1791 /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs,
1792 drop to VR_VARYING. It would take more effort to compute a
1793 precise range for such a case. For example, if we have
1794 op0 == 65536 and op1 == 65536 with their ranges both being
1795 ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so
1796 we cannot claim that the product is in ~[0,0]. Note that we
1797 are guaranteed to have vr0.type == vr1.type at this
1799 if (code
== MULT_EXPR
1800 && vr0
.type
== VR_ANTI_RANGE
1801 && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0
)))
1803 set_value_range_to_varying (vr
);
1807 /* Multiplications and divisions are a bit tricky to handle,
1808 depending on the mix of signs we have in the two ranges, we
1809 need to operate on different values to get the minimum and
1810 maximum values for the new range. One approach is to figure
1811 out all the variations of range combinations and do the
1814 However, this involves several calls to compare_values and it
1815 is pretty convoluted. It's simpler to do the 4 operations
1816 (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP
1817 MAX1) and then figure the smallest and largest values to form
1820 /* Divisions by zero result in a VARYING value. */
1821 if (code
!= MULT_EXPR
1822 && (vr0
.type
== VR_ANTI_RANGE
|| range_includes_zero_p (&vr1
)))
1824 set_value_range_to_varying (vr
);
1828 /* Compute the 4 cross operations. */
1830 val
[0] = vrp_int_const_binop (code
, vr0
.min
, vr1
.min
);
1831 if (val
[0] == NULL_TREE
)
1834 if (vr1
.max
== vr1
.min
)
1838 val
[1] = vrp_int_const_binop (code
, vr0
.min
, vr1
.max
);
1839 if (val
[1] == NULL_TREE
)
1843 if (vr0
.max
== vr0
.min
)
1847 val
[2] = vrp_int_const_binop (code
, vr0
.max
, vr1
.min
);
1848 if (val
[2] == NULL_TREE
)
1852 if (vr0
.min
== vr0
.max
|| vr1
.min
== vr1
.max
)
1856 val
[3] = vrp_int_const_binop (code
, vr0
.max
, vr1
.max
);
1857 if (val
[3] == NULL_TREE
)
1863 set_value_range_to_varying (vr
);
1867 /* Set MIN to the minimum of VAL[i] and MAX to the maximum
1871 for (i
= 1; i
< 4; i
++)
1873 if (!is_gimple_min_invariant (min
)
1874 || (TREE_OVERFLOW (min
) && !is_overflow_infinity (min
))
1875 || !is_gimple_min_invariant (max
)
1876 || (TREE_OVERFLOW (max
) && !is_overflow_infinity (max
)))
1881 if (!is_gimple_min_invariant (val
[i
])
1882 || (TREE_OVERFLOW (val
[i
])
1883 && !is_overflow_infinity (val
[i
])))
1885 /* If we found an overflowed value, set MIN and MAX
1886 to it so that we set the resulting range to
1892 if (compare_values (val
[i
], min
) == -1)
1895 if (compare_values (val
[i
], max
) == 1)
1900 else if (code
== MINUS_EXPR
)
1902 /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to
1903 VR_VARYING. It would take more effort to compute a precise
1904 range for such a case. For example, if we have op0 == 1 and
1905 op1 == 1 with their ranges both being ~[0,0], we would have
1906 op0 - op1 == 0, so we cannot claim that the difference is in
1907 ~[0,0]. Note that we are guaranteed to have
1908 vr0.type == vr1.type at this point. */
1909 if (vr0
.type
== VR_ANTI_RANGE
)
1911 set_value_range_to_varying (vr
);
1915 /* For MINUS_EXPR, apply the operation to the opposite ends of
1917 min
= vrp_int_const_binop (code
, vr0
.min
, vr1
.max
);
1918 max
= vrp_int_const_binop (code
, vr0
.max
, vr1
.min
);
1920 else if (code
== BIT_AND_EXPR
)
1922 if (vr0
.type
== VR_RANGE
1923 && vr0
.min
== vr0
.max
1924 && TREE_CODE (vr0
.max
) == INTEGER_CST
1925 && !TREE_OVERFLOW (vr0
.max
)
1926 && tree_int_cst_sgn (vr0
.max
) >= 0)
1928 min
= build_int_cst (TREE_TYPE (expr
), 0);
1931 else if (vr1
.type
== VR_RANGE
1932 && vr1
.min
== vr1
.max
1933 && TREE_CODE (vr1
.max
) == INTEGER_CST
1934 && !TREE_OVERFLOW (vr1
.max
)
1935 && tree_int_cst_sgn (vr1
.max
) >= 0)
1938 min
= build_int_cst (TREE_TYPE (expr
), 0);
1943 set_value_range_to_varying (vr
);
1950 /* If either MIN or MAX overflowed, then set the resulting range to
1951 VARYING. But we do accept an overflow infinity
1953 if (min
== NULL_TREE
1954 || !is_gimple_min_invariant (min
)
1955 || (TREE_OVERFLOW (min
) && !is_overflow_infinity (min
))
1957 || !is_gimple_min_invariant (max
)
1958 || (TREE_OVERFLOW (max
) && !is_overflow_infinity (max
)))
1960 set_value_range_to_varying (vr
);
1966 2) [-INF, +-INF(OVF)]
1967 3) [+-INF(OVF), +INF]
1968 4) [+-INF(OVF), +-INF(OVF)]
1969 We learn nothing when we have INF and INF(OVF) on both sides.
1970 Note that we do accept [-INF, -INF] and [+INF, +INF] without
1972 if ((vrp_val_is_min (min
) || is_overflow_infinity (min
))
1973 && (vrp_val_is_max (max
) || is_overflow_infinity (max
)))
1975 set_value_range_to_varying (vr
);
1979 cmp
= compare_values (min
, max
);
1980 if (cmp
== -2 || cmp
== 1)
1982 /* If the new range has its limits swapped around (MIN > MAX),
1983 then the operation caused one of them to wrap around, mark
1984 the new range VARYING. */
1985 set_value_range_to_varying (vr
);
1988 set_value_range (vr
, type
, min
, max
, NULL
);
1992 /* Extract range information from a unary expression EXPR based on
1993 the range of its operand and the expression code. */
1996 extract_range_from_unary_expr (value_range_t
*vr
, tree expr
)
1998 enum tree_code code
= TREE_CODE (expr
);
2001 value_range_t vr0
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
2003 /* Refuse to operate on certain unary expressions for which we
2004 cannot easily determine a resulting range. */
2005 if (code
== FIX_TRUNC_EXPR
2006 || code
== FIX_CEIL_EXPR
2007 || code
== FIX_FLOOR_EXPR
2008 || code
== FIX_ROUND_EXPR
2009 || code
== FLOAT_EXPR
2010 || code
== BIT_NOT_EXPR
2011 || code
== NON_LVALUE_EXPR
2012 || code
== CONJ_EXPR
)
2014 set_value_range_to_varying (vr
);
2018 /* Get value ranges for the operand. For constant operands, create
2019 a new value range with the operand to simplify processing. */
2020 op0
= TREE_OPERAND (expr
, 0);
2021 if (TREE_CODE (op0
) == SSA_NAME
)
2022 vr0
= *(get_value_range (op0
));
2023 else if (is_gimple_min_invariant (op0
))
2024 set_value_range_to_value (&vr0
, op0
, NULL
);
2026 set_value_range_to_varying (&vr0
);
2028 /* If VR0 is UNDEFINED, so is the result. */
2029 if (vr0
.type
== VR_UNDEFINED
)
2031 set_value_range_to_undefined (vr
);
2035 /* Refuse to operate on symbolic ranges, or if neither operand is
2036 a pointer or integral type. */
2037 if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
2038 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
2039 || (vr0
.type
!= VR_VARYING
2040 && symbolic_range_p (&vr0
)))
2042 set_value_range_to_varying (vr
);
2046 /* If the expression involves pointers, we are only interested in
2047 determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */
2048 if (POINTER_TYPE_P (TREE_TYPE (expr
)) || POINTER_TYPE_P (TREE_TYPE (op0
)))
2053 if (range_is_nonnull (&vr0
)
2054 || (tree_expr_nonzero_warnv_p (expr
, &sop
)
2056 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
2057 else if (range_is_null (&vr0
))
2058 set_value_range_to_null (vr
, TREE_TYPE (expr
));
2060 set_value_range_to_varying (vr
);
2065 /* Handle unary expressions on integer ranges. */
2066 if (code
== NOP_EXPR
|| code
== CONVERT_EXPR
)
2068 tree inner_type
= TREE_TYPE (op0
);
2069 tree outer_type
= TREE_TYPE (expr
);
2071 /* If VR0 represents a simple range, then try to convert
2072 the min and max values for the range to the same type
2073 as OUTER_TYPE. If the results compare equal to VR0's
2074 min and max values and the new min is still less than
2075 or equal to the new max, then we can safely use the newly
2076 computed range for EXPR. This allows us to compute
2077 accurate ranges through many casts. */
2078 if ((vr0
.type
== VR_RANGE
2079 && !overflow_infinity_range_p (&vr0
))
2080 || (vr0
.type
== VR_VARYING
2081 && TYPE_PRECISION (outer_type
) > TYPE_PRECISION (inner_type
)))
2083 tree new_min
, new_max
, orig_min
, orig_max
;
2085 /* Convert the input operand min/max to OUTER_TYPE. If
2086 the input has no range information, then use the min/max
2087 for the input's type. */
2088 if (vr0
.type
== VR_RANGE
)
2095 orig_min
= TYPE_MIN_VALUE (inner_type
);
2096 orig_max
= TYPE_MAX_VALUE (inner_type
);
2099 new_min
= fold_convert (outer_type
, orig_min
);
2100 new_max
= fold_convert (outer_type
, orig_max
);
2102 /* Verify the new min/max values are gimple values and
2103 that they compare equal to the original input's
2105 if (is_gimple_val (new_min
)
2106 && is_gimple_val (new_max
)
2107 && tree_int_cst_equal (new_min
, orig_min
)
2108 && tree_int_cst_equal (new_max
, orig_max
)
2109 && (!is_overflow_infinity (new_min
)
2110 || !is_overflow_infinity (new_max
))
2111 && compare_values (new_min
, new_max
) <= 0
2112 && compare_values (new_min
, new_max
) >= -1)
2114 set_value_range (vr
, VR_RANGE
, new_min
, new_max
, vr
->equiv
);
2119 /* When converting types of different sizes, set the result to
2120 VARYING. Things like sign extensions and precision loss may
2121 change the range. For instance, if x_3 is of type 'long long
2122 int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it
2123 is impossible to know at compile time whether y_5 will be
2125 if (TYPE_SIZE (inner_type
) != TYPE_SIZE (outer_type
)
2126 || TYPE_PRECISION (inner_type
) != TYPE_PRECISION (outer_type
))
2128 set_value_range_to_varying (vr
);
2133 /* Conversion of a VR_VARYING value to a wider type can result
2134 in a usable range. So wait until after we've handled conversions
2135 before dropping the result to VR_VARYING if we had a source
2136 operand that is VR_VARYING. */
2137 if (vr0
.type
== VR_VARYING
)
2139 set_value_range_to_varying (vr
);
2143 /* Apply the operation to each end of the range and see what we end
2145 if (code
== NEGATE_EXPR
2146 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
2148 /* NEGATE_EXPR flips the range around. We need to treat
2149 TYPE_MIN_VALUE specially. */
2150 if (is_positive_overflow_infinity (vr0
.max
))
2151 min
= negative_overflow_infinity (TREE_TYPE (expr
));
2152 else if (is_negative_overflow_infinity (vr0
.max
))
2153 min
= positive_overflow_infinity (TREE_TYPE (expr
));
2154 else if (!vrp_val_is_min (vr0
.max
))
2155 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
2156 else if (needs_overflow_infinity (TREE_TYPE (expr
)))
2158 if (supports_overflow_infinity (TREE_TYPE (expr
))
2159 && !is_overflow_infinity (vr0
.min
)
2160 && !vrp_val_is_min (vr0
.min
))
2161 min
= positive_overflow_infinity (TREE_TYPE (expr
));
2164 set_value_range_to_varying (vr
);
2169 min
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
2171 if (is_positive_overflow_infinity (vr0
.min
))
2172 max
= negative_overflow_infinity (TREE_TYPE (expr
));
2173 else if (is_negative_overflow_infinity (vr0
.min
))
2174 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2175 else if (!vrp_val_is_min (vr0
.min
))
2176 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
2177 else if (needs_overflow_infinity (TREE_TYPE (expr
)))
2179 if (supports_overflow_infinity (TREE_TYPE (expr
)))
2180 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2183 set_value_range_to_varying (vr
);
2188 max
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
2190 else if (code
== NEGATE_EXPR
2191 && TYPE_UNSIGNED (TREE_TYPE (expr
)))
2193 if (!range_includes_zero_p (&vr0
))
2195 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
2196 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
2200 if (range_is_null (&vr0
))
2201 set_value_range_to_null (vr
, TREE_TYPE (expr
));
2203 set_value_range_to_varying (vr
);
2207 else if (code
== ABS_EXPR
2208 && !TYPE_UNSIGNED (TREE_TYPE (expr
)))
2210 /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a
2212 if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (expr
))
2213 && ((vr0
.type
== VR_RANGE
2214 && vrp_val_is_min (vr0
.min
))
2215 || (vr0
.type
== VR_ANTI_RANGE
2216 && !vrp_val_is_min (vr0
.min
)
2217 && !range_includes_zero_p (&vr0
))))
2219 set_value_range_to_varying (vr
);
2223 /* ABS_EXPR may flip the range around, if the original range
2224 included negative values. */
2225 if (is_overflow_infinity (vr0
.min
))
2226 min
= positive_overflow_infinity (TREE_TYPE (expr
));
2227 else if (!vrp_val_is_min (vr0
.min
))
2228 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
2229 else if (!needs_overflow_infinity (TREE_TYPE (expr
)))
2230 min
= TYPE_MAX_VALUE (TREE_TYPE (expr
));
2231 else if (supports_overflow_infinity (TREE_TYPE (expr
)))
2232 min
= positive_overflow_infinity (TREE_TYPE (expr
));
2235 set_value_range_to_varying (vr
);
2239 if (is_overflow_infinity (vr0
.max
))
2240 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2241 else if (!vrp_val_is_min (vr0
.max
))
2242 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
2243 else if (!needs_overflow_infinity (TREE_TYPE (expr
)))
2244 max
= TYPE_MAX_VALUE (TREE_TYPE (expr
));
2245 else if (supports_overflow_infinity (TREE_TYPE (expr
)))
2246 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2249 set_value_range_to_varying (vr
);
2253 cmp
= compare_values (min
, max
);
2255 /* If a VR_ANTI_RANGEs contains zero, then we have
2256 ~[-INF, min(MIN, MAX)]. */
2257 if (vr0
.type
== VR_ANTI_RANGE
)
2259 if (range_includes_zero_p (&vr0
))
2261 /* Take the lower of the two values. */
2265 /* Create ~[-INF, min (abs(MIN), abs(MAX))]
2266 or ~[-INF + 1, min (abs(MIN), abs(MAX))] when
2267 flag_wrapv is set and the original anti-range doesn't include
2268 TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */
2269 if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr
)))
2271 tree type_min_value
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
2273 min
= (vr0
.min
!= type_min_value
2274 ? int_const_binop (PLUS_EXPR
, type_min_value
,
2275 integer_one_node
, 0)
2280 if (overflow_infinity_range_p (&vr0
))
2281 min
= negative_overflow_infinity (TREE_TYPE (expr
));
2283 min
= TYPE_MIN_VALUE (TREE_TYPE (expr
));
2288 /* All else has failed, so create the range [0, INF], even for
2289 flag_wrapv since TYPE_MIN_VALUE is in the original
2291 vr0
.type
= VR_RANGE
;
2292 min
= build_int_cst (TREE_TYPE (expr
), 0);
2293 if (needs_overflow_infinity (TREE_TYPE (expr
)))
2295 if (supports_overflow_infinity (TREE_TYPE (expr
)))
2296 max
= positive_overflow_infinity (TREE_TYPE (expr
));
2299 set_value_range_to_varying (vr
);
2304 max
= TYPE_MAX_VALUE (TREE_TYPE (expr
));
2308 /* If the range contains zero then we know that the minimum value in the
2309 range will be zero. */
2310 else if (range_includes_zero_p (&vr0
))
2314 min
= build_int_cst (TREE_TYPE (expr
), 0);
2318 /* If the range was reversed, swap MIN and MAX. */
2329 /* Otherwise, operate on each end of the range. */
2330 min
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.min
);
2331 max
= fold_unary_to_constant (code
, TREE_TYPE (expr
), vr0
.max
);
2333 if (needs_overflow_infinity (TREE_TYPE (expr
)))
2335 gcc_assert (code
!= NEGATE_EXPR
&& code
!= ABS_EXPR
);
2337 /* If both sides have overflowed, we don't know
2339 if ((is_overflow_infinity (vr0
.min
)
2340 || TREE_OVERFLOW (min
))
2341 && (is_overflow_infinity (vr0
.max
)
2342 || TREE_OVERFLOW (max
)))
2344 set_value_range_to_varying (vr
);
2348 if (is_overflow_infinity (vr0
.min
))
2350 else if (TREE_OVERFLOW (min
))
2352 if (supports_overflow_infinity (TREE_TYPE (expr
)))
2353 min
= (tree_int_cst_sgn (min
) >= 0
2354 ? positive_overflow_infinity (TREE_TYPE (min
))
2355 : negative_overflow_infinity (TREE_TYPE (min
)));
2358 set_value_range_to_varying (vr
);
2363 if (is_overflow_infinity (vr0
.max
))
2365 else if (TREE_OVERFLOW (max
))
2367 if (supports_overflow_infinity (TREE_TYPE (expr
)))
2368 max
= (tree_int_cst_sgn (max
) >= 0
2369 ? positive_overflow_infinity (TREE_TYPE (max
))
2370 : negative_overflow_infinity (TREE_TYPE (max
)));
2373 set_value_range_to_varying (vr
);
2380 cmp
= compare_values (min
, max
);
2381 if (cmp
== -2 || cmp
== 1)
2383 /* If the new range has its limits swapped around (MIN > MAX),
2384 then the operation caused one of them to wrap around, mark
2385 the new range VARYING. */
2386 set_value_range_to_varying (vr
);
2389 set_value_range (vr
, vr0
.type
, min
, max
, NULL
);
2393 /* Extract range information from a comparison expression EXPR based
2394 on the range of its operand and the expression code. */
2397 extract_range_from_comparison (value_range_t
*vr
, tree expr
)
2400 tree val
= vrp_evaluate_conditional_warnv (expr
, false, &sop
);
2402 /* A disadvantage of using a special infinity as an overflow
2403 representation is that we lose the ability to record overflow
2404 when we don't have an infinity. So we have to ignore a result
2405 which relies on overflow. */
2407 if (val
&& !is_overflow_infinity (val
) && !sop
)
2409 /* Since this expression was found on the RHS of an assignment,
2410 its type may be different from _Bool. Convert VAL to EXPR's
2412 val
= fold_convert (TREE_TYPE (expr
), val
);
2413 if (is_gimple_min_invariant (val
))
2414 set_value_range_to_value (vr
, val
, vr
->equiv
);
2416 set_value_range (vr
, VR_RANGE
, val
, val
, vr
->equiv
);
2419 set_value_range_to_varying (vr
);
2423 /* Try to compute a useful range out of expression EXPR and store it
2427 extract_range_from_expr (value_range_t
*vr
, tree expr
)
2429 enum tree_code code
= TREE_CODE (expr
);
2431 if (code
== ASSERT_EXPR
)
2432 extract_range_from_assert (vr
, expr
);
2433 else if (code
== SSA_NAME
)
2434 extract_range_from_ssa_name (vr
, expr
);
2435 else if (TREE_CODE_CLASS (code
) == tcc_binary
2436 || code
== TRUTH_ANDIF_EXPR
2437 || code
== TRUTH_ORIF_EXPR
2438 || code
== TRUTH_AND_EXPR
2439 || code
== TRUTH_OR_EXPR
2440 || code
== TRUTH_XOR_EXPR
)
2441 extract_range_from_binary_expr (vr
, expr
);
2442 else if (TREE_CODE_CLASS (code
) == tcc_unary
)
2443 extract_range_from_unary_expr (vr
, expr
);
2444 else if (TREE_CODE_CLASS (code
) == tcc_comparison
)
2445 extract_range_from_comparison (vr
, expr
);
2446 else if (is_gimple_min_invariant (expr
))
2447 set_value_range_to_value (vr
, expr
, NULL
);
2449 set_value_range_to_varying (vr
);
2451 /* If we got a varying range from the tests above, try a final
2452 time to derive a nonnegative or nonzero range. This time
2453 relying primarily on generic routines in fold in conjunction
2455 if (vr
->type
== VR_VARYING
)
2459 if (INTEGRAL_TYPE_P (TREE_TYPE (expr
))
2460 && vrp_expr_computes_nonnegative (expr
, &sop
))
2461 set_value_range_to_nonnegative (vr
, TREE_TYPE (expr
),
2462 sop
|| is_overflow_infinity (expr
));
2463 else if (vrp_expr_computes_nonzero (expr
, &sop
)
2465 set_value_range_to_nonnull (vr
, TREE_TYPE (expr
));
2469 /* Given a range VR, a LOOP and a variable VAR, determine whether it
2470 would be profitable to adjust VR using scalar evolution information
2471 for VAR. If so, update VR with the new limits. */
2474 adjust_range_with_scev (value_range_t
*vr
, struct loop
*loop
, tree stmt
,
2477 tree init
, step
, chrec
, tmin
, tmax
, min
, max
, type
;
2478 enum ev_direction dir
;
2480 /* TODO. Don't adjust anti-ranges. An anti-range may provide
2481 better opportunities than a regular range, but I'm not sure. */
2482 if (vr
->type
== VR_ANTI_RANGE
)
2485 chrec
= instantiate_parameters (loop
, analyze_scalar_evolution (loop
, var
));
2486 if (TREE_CODE (chrec
) != POLYNOMIAL_CHREC
)
2489 init
= initial_condition_in_loop_num (chrec
, loop
->num
);
2490 step
= evolution_part_in_loop_num (chrec
, loop
->num
);
2492 /* If STEP is symbolic, we can't know whether INIT will be the
2493 minimum or maximum value in the range. Also, unless INIT is
2494 a simple expression, compare_values and possibly other functions
2495 in tree-vrp won't be able to handle it. */
2496 if (step
== NULL_TREE
2497 || !is_gimple_min_invariant (step
)
2498 || !valid_value_p (init
))
2501 dir
= scev_direction (chrec
);
2502 if (/* Do not adjust ranges if we do not know whether the iv increases
2503 or decreases, ... */
2504 dir
== EV_DIR_UNKNOWN
2505 /* ... or if it may wrap. */
2506 || scev_probably_wraps_p (init
, step
, stmt
,
2507 current_loops
->parray
[CHREC_VARIABLE (chrec
)],
2511 /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of
2512 negative_overflow_infinity and positive_overflow_infinity,
2513 because we have concluded that the loop probably does not
2516 type
= TREE_TYPE (var
);
2517 if (POINTER_TYPE_P (type
) || !TYPE_MIN_VALUE (type
))
2518 tmin
= lower_bound_in_type (type
, type
);
2520 tmin
= TYPE_MIN_VALUE (type
);
2521 if (POINTER_TYPE_P (type
) || !TYPE_MAX_VALUE (type
))
2522 tmax
= upper_bound_in_type (type
, type
);
2524 tmax
= TYPE_MAX_VALUE (type
);
2526 if (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
)
2531 /* For VARYING or UNDEFINED ranges, just about anything we get
2532 from scalar evolutions should be better. */
2534 if (dir
== EV_DIR_DECREASES
)
2539 /* If we would create an invalid range, then just assume we
2540 know absolutely nothing. This may be over-conservative,
2541 but it's clearly safe, and should happen only in unreachable
2542 parts of code, or for invalid programs. */
2543 if (compare_values (min
, max
) == 1)
2546 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
2548 else if (vr
->type
== VR_RANGE
)
2553 if (dir
== EV_DIR_DECREASES
)
2555 /* INIT is the maximum value. If INIT is lower than VR->MAX
2556 but no smaller than VR->MIN, set VR->MAX to INIT. */
2557 if (compare_values (init
, max
) == -1)
2561 /* If we just created an invalid range with the minimum
2562 greater than the maximum, we fail conservatively.
2563 This should happen only in unreachable
2564 parts of code, or for invalid programs. */
2565 if (compare_values (min
, max
) == 1)
2569 /* According to the loop information, the variable does not
2570 overflow. If we think it does, probably because of an
2571 overflow due to arithmetic on a different INF value,
2573 if (is_negative_overflow_infinity (min
))
2578 /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */
2579 if (compare_values (init
, min
) == 1)
2583 /* Again, avoid creating invalid range by failing. */
2584 if (compare_values (min
, max
) == 1)
2588 if (is_positive_overflow_infinity (max
))
2592 set_value_range (vr
, VR_RANGE
, min
, max
, vr
->equiv
);
2596 /* Return true if VAR may overflow at STMT. This checks any available
2597 loop information to see if we can determine that VAR does not
2601 vrp_var_may_overflow (tree var
, tree stmt
)
2604 tree chrec
, init
, step
;
2606 if (current_loops
== NULL
)
2609 l
= loop_containing_stmt (stmt
);
2613 chrec
= instantiate_parameters (l
, analyze_scalar_evolution (l
, var
));
2614 if (TREE_CODE (chrec
) != POLYNOMIAL_CHREC
)
2617 init
= initial_condition_in_loop_num (chrec
, l
->num
);
2618 step
= evolution_part_in_loop_num (chrec
, l
->num
);
2620 if (step
== NULL_TREE
2621 || !is_gimple_min_invariant (step
)
2622 || !valid_value_p (init
))
2625 /* If we get here, we know something useful about VAR based on the
2626 loop information. If it wraps, it may overflow. */
2628 if (scev_probably_wraps_p (init
, step
, stmt
,
2629 current_loops
->parray
[CHREC_VARIABLE (chrec
)],
2633 if (dump_file
&& (dump_flags
& TDF_DETAILS
) != 0)
2635 print_generic_expr (dump_file
, var
, 0);
2636 fprintf (dump_file
, ": loop information indicates does not overflow\n");
2643 /* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
2645 - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
2646 all the values in the ranges.
2648 - Return BOOLEAN_FALSE_NODE if the comparison always returns false.
2650 - Return NULL_TREE if it is not always possible to determine the
2651 value of the comparison.
2653 Also set *STRICT_OVERFLOW_P to indicate whether a range with an
2654 overflow infinity was used in the test. */
2658 compare_ranges (enum tree_code comp
, value_range_t
*vr0
, value_range_t
*vr1
,
2659 bool *strict_overflow_p
)
2661 /* VARYING or UNDEFINED ranges cannot be compared. */
2662 if (vr0
->type
== VR_VARYING
2663 || vr0
->type
== VR_UNDEFINED
2664 || vr1
->type
== VR_VARYING
2665 || vr1
->type
== VR_UNDEFINED
)
2668 /* Anti-ranges need to be handled separately. */
2669 if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
2671 /* If both are anti-ranges, then we cannot compute any
2673 if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
2676 /* These comparisons are never statically computable. */
2683 /* Equality can be computed only between a range and an
2684 anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
2685 if (vr0
->type
== VR_RANGE
)
2687 /* To simplify processing, make VR0 the anti-range. */
2688 value_range_t
*tmp
= vr0
;
2693 gcc_assert (comp
== NE_EXPR
|| comp
== EQ_EXPR
);
2695 if (compare_values_warnv (vr0
->min
, vr1
->min
, strict_overflow_p
) == 0
2696 && compare_values_warnv (vr0
->max
, vr1
->max
, strict_overflow_p
) == 0)
2697 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
2702 if (!usable_range_p (vr0
, strict_overflow_p
)
2703 || !usable_range_p (vr1
, strict_overflow_p
))
2706 /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
2707 operands around and change the comparison code. */
2708 if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
2711 comp
= (comp
== GT_EXPR
) ? LT_EXPR
: LE_EXPR
;
2717 if (comp
== EQ_EXPR
)
2719 /* Equality may only be computed if both ranges represent
2720 exactly one value. */
2721 if (compare_values_warnv (vr0
->min
, vr0
->max
, strict_overflow_p
) == 0
2722 && compare_values_warnv (vr1
->min
, vr1
->max
, strict_overflow_p
) == 0)
2724 int cmp_min
= compare_values_warnv (vr0
->min
, vr1
->min
,
2726 int cmp_max
= compare_values_warnv (vr0
->max
, vr1
->max
,
2728 if (cmp_min
== 0 && cmp_max
== 0)
2729 return boolean_true_node
;
2730 else if (cmp_min
!= -2 && cmp_max
!= -2)
2731 return boolean_false_node
;
2733 /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
2734 else if (compare_values_warnv (vr0
->min
, vr1
->max
,
2735 strict_overflow_p
) == 1
2736 || compare_values_warnv (vr1
->min
, vr0
->max
,
2737 strict_overflow_p
) == 1)
2738 return boolean_false_node
;
2742 else if (comp
== NE_EXPR
)
2746 /* If VR0 is completely to the left or completely to the right
2747 of VR1, they are always different. Notice that we need to
2748 make sure that both comparisons yield similar results to
2749 avoid comparing values that cannot be compared at
2751 cmp1
= compare_values_warnv (vr0
->max
, vr1
->min
, strict_overflow_p
);
2752 cmp2
= compare_values_warnv (vr0
->min
, vr1
->max
, strict_overflow_p
);
2753 if ((cmp1
== -1 && cmp2
== -1) || (cmp1
== 1 && cmp2
== 1))
2754 return boolean_true_node
;
2756 /* If VR0 and VR1 represent a single value and are identical,
2758 else if (compare_values_warnv (vr0
->min
, vr0
->max
,
2759 strict_overflow_p
) == 0
2760 && compare_values_warnv (vr1
->min
, vr1
->max
,
2761 strict_overflow_p
) == 0
2762 && compare_values_warnv (vr0
->min
, vr1
->min
,
2763 strict_overflow_p
) == 0
2764 && compare_values_warnv (vr0
->max
, vr1
->max
,
2765 strict_overflow_p
) == 0)
2766 return boolean_false_node
;
2768 /* Otherwise, they may or may not be different. */
2772 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
2776 /* If VR0 is to the left of VR1, return true. */
2777 tst
= compare_values_warnv (vr0
->max
, vr1
->min
, strict_overflow_p
);
2778 if ((comp
== LT_EXPR
&& tst
== -1)
2779 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
2781 if (overflow_infinity_range_p (vr0
)
2782 || overflow_infinity_range_p (vr1
))
2783 *strict_overflow_p
= true;
2784 return boolean_true_node
;
2787 /* If VR0 is to the right of VR1, return false. */
2788 tst
= compare_values_warnv (vr0
->min
, vr1
->max
, strict_overflow_p
);
2789 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
2790 || (comp
== LE_EXPR
&& tst
== 1))
2792 if (overflow_infinity_range_p (vr0
)
2793 || overflow_infinity_range_p (vr1
))
2794 *strict_overflow_p
= true;
2795 return boolean_false_node
;
2798 /* Otherwise, we don't know. */
2806 /* Given a value range VR, a value VAL and a comparison code COMP, return
2807 BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
2808 values in VR. Return BOOLEAN_FALSE_NODE if the comparison
2809 always returns false. Return NULL_TREE if it is not always
2810 possible to determine the value of the comparison. Also set
2811 *STRICT_OVERFLOW_P to indicate whether a range with an overflow
2812 infinity was used in the test. */
2815 compare_range_with_value (enum tree_code comp
, value_range_t
*vr
, tree val
,
2816 bool *strict_overflow_p
)
2818 if (vr
->type
== VR_VARYING
|| vr
->type
== VR_UNDEFINED
)
2821 /* Anti-ranges need to be handled separately. */
2822 if (vr
->type
== VR_ANTI_RANGE
)
2824 /* For anti-ranges, the only predicates that we can compute at
2825 compile time are equality and inequality. */
2832 /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
2833 if (value_inside_range (val
, vr
) == 1)
2834 return (comp
== NE_EXPR
) ? boolean_true_node
: boolean_false_node
;
2839 if (!usable_range_p (vr
, strict_overflow_p
))
2842 if (comp
== EQ_EXPR
)
2844 /* EQ_EXPR may only be computed if VR represents exactly
2846 if (compare_values_warnv (vr
->min
, vr
->max
, strict_overflow_p
) == 0)
2848 int cmp
= compare_values_warnv (vr
->min
, val
, strict_overflow_p
);
2850 return boolean_true_node
;
2851 else if (cmp
== -1 || cmp
== 1 || cmp
== 2)
2852 return boolean_false_node
;
2854 else if (compare_values_warnv (val
, vr
->min
, strict_overflow_p
) == -1
2855 || compare_values_warnv (vr
->max
, val
, strict_overflow_p
) == -1)
2856 return boolean_false_node
;
2860 else if (comp
== NE_EXPR
)
2862 /* If VAL is not inside VR, then they are always different. */
2863 if (compare_values_warnv (vr
->max
, val
, strict_overflow_p
) == -1
2864 || compare_values_warnv (vr
->min
, val
, strict_overflow_p
) == 1)
2865 return boolean_true_node
;
2867 /* If VR represents exactly one value equal to VAL, then return
2869 if (compare_values_warnv (vr
->min
, vr
->max
, strict_overflow_p
) == 0
2870 && compare_values_warnv (vr
->min
, val
, strict_overflow_p
) == 0)
2871 return boolean_false_node
;
2873 /* Otherwise, they may or may not be different. */
2876 else if (comp
== LT_EXPR
|| comp
== LE_EXPR
)
2880 /* If VR is to the left of VAL, return true. */
2881 tst
= compare_values_warnv (vr
->max
, val
, strict_overflow_p
);
2882 if ((comp
== LT_EXPR
&& tst
== -1)
2883 || (comp
== LE_EXPR
&& (tst
== -1 || tst
== 0)))
2885 if (overflow_infinity_range_p (vr
))
2886 *strict_overflow_p
= true;
2887 return boolean_true_node
;
2890 /* If VR is to the right of VAL, return false. */
2891 tst
= compare_values_warnv (vr
->min
, val
, strict_overflow_p
);
2892 if ((comp
== LT_EXPR
&& (tst
== 0 || tst
== 1))
2893 || (comp
== LE_EXPR
&& tst
== 1))
2895 if (overflow_infinity_range_p (vr
))
2896 *strict_overflow_p
= true;
2897 return boolean_false_node
;
2900 /* Otherwise, we don't know. */
2903 else if (comp
== GT_EXPR
|| comp
== GE_EXPR
)
2907 /* If VR is to the right of VAL, return true. */
2908 tst
= compare_values_warnv (vr
->min
, val
, strict_overflow_p
);
2909 if ((comp
== GT_EXPR
&& tst
== 1)
2910 || (comp
== GE_EXPR
&& (tst
== 0 || tst
== 1)))
2912 if (overflow_infinity_range_p (vr
))
2913 *strict_overflow_p
= true;
2914 return boolean_true_node
;
2917 /* If VR is to the left of VAL, return false. */
2918 tst
= compare_values_warnv (vr
->max
, val
, strict_overflow_p
);
2919 if ((comp
== GT_EXPR
&& (tst
== -1 || tst
== 0))
2920 || (comp
== GE_EXPR
&& tst
== -1))
2922 if (overflow_infinity_range_p (vr
))
2923 *strict_overflow_p
= true;
2924 return boolean_false_node
;
2927 /* Otherwise, we don't know. */
2935 /* Debugging dumps. */
2937 void dump_value_range (FILE *, value_range_t
*);
2938 void debug_value_range (value_range_t
*);
2939 void dump_all_value_ranges (FILE *);
2940 void debug_all_value_ranges (void);
2941 void dump_vr_equiv (FILE *, bitmap
);
2942 void debug_vr_equiv (bitmap
);
2945 /* Dump value range VR to FILE. */
2948 dump_value_range (FILE *file
, value_range_t
*vr
)
2951 fprintf (file
, "[]");
2952 else if (vr
->type
== VR_UNDEFINED
)
2953 fprintf (file
, "UNDEFINED");
2954 else if (vr
->type
== VR_RANGE
|| vr
->type
== VR_ANTI_RANGE
)
2956 tree type
= TREE_TYPE (vr
->min
);
2958 fprintf (file
, "%s[", (vr
->type
== VR_ANTI_RANGE
) ? "~" : "");
2960 if (is_negative_overflow_infinity (vr
->min
))
2961 fprintf (file
, "-INF(OVF)");
2962 else if (INTEGRAL_TYPE_P (type
)
2963 && !TYPE_UNSIGNED (type
)
2964 && vrp_val_is_min (vr
->min
))
2965 fprintf (file
, "-INF");
2967 print_generic_expr (file
, vr
->min
, 0);
2969 fprintf (file
, ", ");
2971 if (is_positive_overflow_infinity (vr
->max
))
2972 fprintf (file
, "+INF(OVF)");
2973 else if (INTEGRAL_TYPE_P (type
)
2974 && vrp_val_is_max (vr
->max
))
2975 fprintf (file
, "+INF");
2977 print_generic_expr (file
, vr
->max
, 0);
2979 fprintf (file
, "]");
2986 fprintf (file
, " EQUIVALENCES: { ");
2988 EXECUTE_IF_SET_IN_BITMAP (vr
->equiv
, 0, i
, bi
)
2990 print_generic_expr (file
, ssa_name (i
), 0);
2991 fprintf (file
, " ");
2995 fprintf (file
, "} (%u elements)", c
);
2998 else if (vr
->type
== VR_VARYING
)
2999 fprintf (file
, "VARYING");
3001 fprintf (file
, "INVALID RANGE");
3005 /* Dump value range VR to stderr. */
3008 debug_value_range (value_range_t
*vr
)
3010 dump_value_range (stderr
, vr
);
3011 fprintf (stderr
, "\n");
3015 /* Dump value ranges of all SSA_NAMEs to FILE. */
3018 dump_all_value_ranges (FILE *file
)
3022 for (i
= 0; i
< num_ssa_names
; i
++)
3026 print_generic_expr (file
, ssa_name (i
), 0);
3027 fprintf (file
, ": ");
3028 dump_value_range (file
, vr_value
[i
]);
3029 fprintf (file
, "\n");
3033 fprintf (file
, "\n");
3037 /* Dump all value ranges to stderr. */
3040 debug_all_value_ranges (void)
3042 dump_all_value_ranges (stderr
);
3046 /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
3047 create a new SSA name N and return the assertion assignment
3048 'V = ASSERT_EXPR <V, V OP W>'. */
3051 build_assert_expr_for (tree cond
, tree v
)
3055 gcc_assert (TREE_CODE (v
) == SSA_NAME
);
3056 n
= duplicate_ssa_name (v
, NULL_TREE
);
3058 if (COMPARISON_CLASS_P (cond
))
3060 tree a
= build2 (ASSERT_EXPR
, TREE_TYPE (v
), v
, cond
);
3061 assertion
= build2 (MODIFY_EXPR
, TREE_TYPE (v
), n
, a
);
3063 else if (TREE_CODE (cond
) == TRUTH_NOT_EXPR
)
3065 /* Given !V, build the assignment N = false. */
3066 tree op0
= TREE_OPERAND (cond
, 0);
3067 gcc_assert (op0
== v
);
3068 assertion
= build2 (MODIFY_EXPR
, TREE_TYPE (v
), n
, boolean_false_node
);
3070 else if (TREE_CODE (cond
) == SSA_NAME
)
3072 /* Given V, build the assignment N = true. */
3073 gcc_assert (v
== cond
);
3074 assertion
= build2 (MODIFY_EXPR
, TREE_TYPE (v
), n
, boolean_true_node
);
3079 SSA_NAME_DEF_STMT (n
) = assertion
;
3081 /* The new ASSERT_EXPR, creates a new SSA name that replaces the
3082 operand of the ASSERT_EXPR. Register the new name and the old one
3083 in the replacement table so that we can fix the SSA web after
3084 adding all the ASSERT_EXPRs. */
3085 register_new_name_mapping (n
, v
);
3091 /* Return false if EXPR is a predicate expression involving floating
3095 fp_predicate (tree expr
)
3097 return (COMPARISON_CLASS_P (expr
)
3098 && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr
, 0))));
3102 /* If the range of values taken by OP can be inferred after STMT executes,
3103 return the comparison code (COMP_CODE_P) and value (VAL_P) that
3104 describes the inferred range. Return true if a range could be
3108 infer_value_range (tree stmt
, tree op
, enum tree_code
*comp_code_p
, tree
*val_p
)
3111 *comp_code_p
= ERROR_MARK
;
3113 /* Do not attempt to infer anything in names that flow through
3115 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op
))
3118 /* Similarly, don't infer anything from statements that may throw
3120 if (tree_could_throw_p (stmt
))
3123 /* If STMT is the last statement of a basic block with no
3124 successors, there is no point inferring anything about any of its
3125 operands. We would not be able to find a proper insertion point
3126 for the assertion, anyway. */
3127 if (stmt_ends_bb_p (stmt
) && EDGE_COUNT (bb_for_stmt (stmt
)->succs
) == 0)
3130 /* We can only assume that a pointer dereference will yield
3131 non-NULL if -fdelete-null-pointer-checks is enabled. */
3132 if (flag_delete_null_pointer_checks
&& POINTER_TYPE_P (TREE_TYPE (op
)))
3135 unsigned num_uses
, num_derefs
;
3137 count_uses_and_derefs (op
, stmt
, &num_uses
, &num_derefs
, &is_store
);
3140 *val_p
= build_int_cst (TREE_TYPE (op
), 0);
3141 *comp_code_p
= NE_EXPR
;
3150 void dump_asserts_for (FILE *, tree
);
3151 void debug_asserts_for (tree
);
3152 void dump_all_asserts (FILE *);
3153 void debug_all_asserts (void);
3155 /* Dump all the registered assertions for NAME to FILE. */
3158 dump_asserts_for (FILE *file
, tree name
)
3162 fprintf (file
, "Assertions to be inserted for ");
3163 print_generic_expr (file
, name
, 0);
3164 fprintf (file
, "\n");
3166 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
3169 fprintf (file
, "\t");
3170 print_generic_expr (file
, bsi_stmt (loc
->si
), 0);
3171 fprintf (file
, "\n\tBB #%d", loc
->bb
->index
);
3174 fprintf (file
, "\n\tEDGE %d->%d", loc
->e
->src
->index
,
3175 loc
->e
->dest
->index
);
3176 dump_edge_info (file
, loc
->e
, 0);
3178 fprintf (file
, "\n\tPREDICATE: ");
3179 print_generic_expr (file
, name
, 0);
3180 fprintf (file
, " %s ", tree_code_name
[(int)loc
->comp_code
]);
3181 print_generic_expr (file
, loc
->val
, 0);
3182 fprintf (file
, "\n\n");
3186 fprintf (file
, "\n");
3190 /* Dump all the registered assertions for NAME to stderr. */
3193 debug_asserts_for (tree name
)
3195 dump_asserts_for (stderr
, name
);
3199 /* Dump all the registered assertions for all the names to FILE. */
3202 dump_all_asserts (FILE *file
)
3207 fprintf (file
, "\nASSERT_EXPRs to be inserted\n\n");
3208 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
3209 dump_asserts_for (file
, ssa_name (i
));
3210 fprintf (file
, "\n");
3214 /* Dump all the registered assertions for all the names to stderr. */
3217 debug_all_asserts (void)
3219 dump_all_asserts (stderr
);
3223 /* If NAME doesn't have an ASSERT_EXPR registered for asserting
3224 'NAME COMP_CODE VAL' at a location that dominates block BB or
3225 E->DEST, then register this location as a possible insertion point
3226 for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>.
3228 BB, E and SI provide the exact insertion point for the new
3229 ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted
3230 on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
3231 BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
3232 must not be NULL. */
3235 register_new_assert_for (tree name
,
3236 enum tree_code comp_code
,
3240 block_stmt_iterator si
)
3242 assert_locus_t n
, loc
, last_loc
;
3244 basic_block dest_bb
;
3246 #if defined ENABLE_CHECKING
3247 gcc_assert (bb
== NULL
|| e
== NULL
);
3250 gcc_assert (TREE_CODE (bsi_stmt (si
)) != COND_EXPR
3251 && TREE_CODE (bsi_stmt (si
)) != SWITCH_EXPR
);
3254 /* The new assertion A will be inserted at BB or E. We need to
3255 determine if the new location is dominated by a previously
3256 registered location for A. If we are doing an edge insertion,
3257 assume that A will be inserted at E->DEST. Note that this is not
3260 If E is a critical edge, it will be split. But even if E is
3261 split, the new block will dominate the same set of blocks that
3264 The reverse, however, is not true, blocks dominated by E->DEST
3265 will not be dominated by the new block created to split E. So,
3266 if the insertion location is on a critical edge, we will not use
3267 the new location to move another assertion previously registered
3268 at a block dominated by E->DEST. */
3269 dest_bb
= (bb
) ? bb
: e
->dest
;
3271 /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
3272 VAL at a block dominating DEST_BB, then we don't need to insert a new
3273 one. Similarly, if the same assertion already exists at a block
3274 dominated by DEST_BB and the new location is not on a critical
3275 edge, then update the existing location for the assertion (i.e.,
3276 move the assertion up in the dominance tree).
3278 Note, this is implemented as a simple linked list because there
3279 should not be more than a handful of assertions registered per
3280 name. If this becomes a performance problem, a table hashed by
3281 COMP_CODE and VAL could be implemented. */
3282 loc
= asserts_for
[SSA_NAME_VERSION (name
)];
3287 if (loc
->comp_code
== comp_code
3289 || operand_equal_p (loc
->val
, val
, 0)))
3291 /* If the assertion NAME COMP_CODE VAL has already been
3292 registered at a basic block that dominates DEST_BB, then
3293 we don't need to insert the same assertion again. Note
3294 that we don't check strict dominance here to avoid
3295 replicating the same assertion inside the same basic
3296 block more than once (e.g., when a pointer is
3297 dereferenced several times inside a block).
3299 An exception to this rule are edge insertions. If the
3300 new assertion is to be inserted on edge E, then it will
3301 dominate all the other insertions that we may want to
3302 insert in DEST_BB. So, if we are doing an edge
3303 insertion, don't do this dominance check. */
3305 && dominated_by_p (CDI_DOMINATORS
, dest_bb
, loc
->bb
))
3308 /* Otherwise, if E is not a critical edge and DEST_BB
3309 dominates the existing location for the assertion, move
3310 the assertion up in the dominance tree by updating its
3311 location information. */
3312 if ((e
== NULL
|| !EDGE_CRITICAL_P (e
))
3313 && dominated_by_p (CDI_DOMINATORS
, loc
->bb
, dest_bb
))
3322 /* Update the last node of the list and move to the next one. */
3327 /* If we didn't find an assertion already registered for
3328 NAME COMP_CODE VAL, add a new one at the end of the list of
3329 assertions associated with NAME. */
3330 n
= XNEW (struct assert_locus_d
);
3334 n
->comp_code
= comp_code
;
3341 asserts_for
[SSA_NAME_VERSION (name
)] = n
;
3343 bitmap_set_bit (need_assert_for
, SSA_NAME_VERSION (name
));
3347 /* Try to register an edge assertion for SSA name NAME on edge E for
3348 the conditional jump pointed to by SI. Return true if an assertion
3349 for NAME could be registered. */
3352 register_edge_assert_for (tree name
, edge e
, block_stmt_iterator si
)
3355 enum tree_code comp_code
;
3357 stmt
= bsi_stmt (si
);
3359 /* Do not attempt to infer anything in names that flow through
3361 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name
))
3364 /* If NAME was not found in the sub-graph reachable from E, then
3365 there's nothing to do. */
3366 if (!TEST_BIT (found_in_subgraph
, SSA_NAME_VERSION (name
)))
3369 /* We found a use of NAME in the sub-graph rooted at E->DEST.
3370 Register an assertion for NAME according to the value that NAME
3372 if (TREE_CODE (stmt
) == COND_EXPR
)
3374 /* If BB ends in a COND_EXPR then NAME then we should insert
3375 the original predicate on EDGE_TRUE_VALUE and the
3376 opposite predicate on EDGE_FALSE_VALUE. */
3377 tree cond
= COND_EXPR_COND (stmt
);
3378 bool is_else_edge
= (e
->flags
& EDGE_FALSE_VALUE
) != 0;
3380 /* Predicates may be a single SSA name or NAME OP VAL. */
3383 /* If the predicate is a name, it must be NAME, in which
3384 case we create the predicate NAME == true or
3385 NAME == false accordingly. */
3386 comp_code
= EQ_EXPR
;
3387 val
= (is_else_edge
) ? boolean_false_node
: boolean_true_node
;
3391 /* Otherwise, we have a comparison of the form NAME COMP VAL
3392 or VAL COMP NAME. */
3393 if (name
== TREE_OPERAND (cond
, 1))
3395 /* If the predicate is of the form VAL COMP NAME, flip
3396 COMP around because we need to register NAME as the
3397 first operand in the predicate. */
3398 comp_code
= swap_tree_comparison (TREE_CODE (cond
));
3399 val
= TREE_OPERAND (cond
, 0);
3403 /* The comparison is of the form NAME COMP VAL, so the
3404 comparison code remains unchanged. */
3405 comp_code
= TREE_CODE (cond
);
3406 val
= TREE_OPERAND (cond
, 1);
3409 /* If we are inserting the assertion on the ELSE edge, we
3410 need to invert the sign comparison. */
3412 comp_code
= invert_tree_comparison (comp_code
, 0);
3414 /* Do not register always-false predicates. FIXME, this
3415 works around a limitation in fold() when dealing with
3416 enumerations. Given 'enum { N1, N2 } x;', fold will not
3417 fold 'if (x > N2)' to 'if (0)'. */
3418 if ((comp_code
== GT_EXPR
|| comp_code
== LT_EXPR
)
3419 && (INTEGRAL_TYPE_P (TREE_TYPE (val
))
3420 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (val
))))
3422 tree min
= TYPE_MIN_VALUE (TREE_TYPE (val
));
3423 tree max
= TYPE_MAX_VALUE (TREE_TYPE (val
));
3425 if (comp_code
== GT_EXPR
&& compare_values (val
, max
) == 0)
3428 if (comp_code
== LT_EXPR
&& compare_values (val
, min
) == 0)
3435 /* FIXME. Handle SWITCH_EXPR. */
3439 register_new_assert_for (name
, comp_code
, val
, NULL
, e
, si
);
3444 static bool find_assert_locations (basic_block bb
);
3446 /* Determine whether the outgoing edges of BB should receive an
3447 ASSERT_EXPR for each of the operands of BB's last statement. The
3448 last statement of BB must be a COND_EXPR or a SWITCH_EXPR.
3450 If any of the sub-graphs rooted at BB have an interesting use of
3451 the predicate operands, an assert location node is added to the
3452 list of assertions for the corresponding operands. */
3455 find_conditional_asserts (basic_block bb
)
3458 block_stmt_iterator last_si
;
3464 need_assert
= false;
3465 last_si
= bsi_last (bb
);
3466 last
= bsi_stmt (last_si
);
3468 /* Look for uses of the operands in each of the sub-graphs
3469 rooted at BB. We need to check each of the outgoing edges
3470 separately, so that we know what kind of ASSERT_EXPR to
3472 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
3477 /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap.
3478 Otherwise, when we finish traversing each of the sub-graphs, we
3479 won't know whether the variables were found in the sub-graphs or
3480 if they had been found in a block upstream from BB.
3482 This is actually a bad idea is some cases, particularly jump
3483 threading. Consider a CFG like the following:
3493 Assume that one or more operands in the conditional at the
3494 end of block 0 are used in a conditional in block 2, but not
3495 anywhere in block 1. In this case we will not insert any
3496 assert statements in block 1, which may cause us to miss
3497 opportunities to optimize, particularly for jump threading. */
3498 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
3499 RESET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3501 /* Traverse the strictly dominated sub-graph rooted at E->DEST
3502 to determine if any of the operands in the conditional
3503 predicate are used. */
3505 need_assert
|= find_assert_locations (e
->dest
);
3507 /* Register the necessary assertions for each operand in the
3508 conditional predicate. */
3509 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
3510 need_assert
|= register_edge_assert_for (op
, e
, last_si
);
3513 /* Finally, indicate that we have found the operands in the
3515 FOR_EACH_SSA_TREE_OPERAND (op
, last
, iter
, SSA_OP_USE
)
3516 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3522 /* Traverse all the statements in block BB looking for statements that
3523 may generate useful assertions for the SSA names in their operand.
3524 If a statement produces a useful assertion A for name N_i, then the
3525 list of assertions already generated for N_i is scanned to
3526 determine if A is actually needed.
3528 If N_i already had the assertion A at a location dominating the
3529 current location, then nothing needs to be done. Otherwise, the
3530 new location for A is recorded instead.
3532 1- For every statement S in BB, all the variables used by S are
3533 added to bitmap FOUND_IN_SUBGRAPH.
3535 2- If statement S uses an operand N in a way that exposes a known
3536 value range for N, then if N was not already generated by an
3537 ASSERT_EXPR, create a new assert location for N. For instance,
3538 if N is a pointer and the statement dereferences it, we can
3539 assume that N is not NULL.
3541 3- COND_EXPRs are a special case of #2. We can derive range
3542 information from the predicate but need to insert different
3543 ASSERT_EXPRs for each of the sub-graphs rooted at the
3544 conditional block. If the last statement of BB is a conditional
3545 expression of the form 'X op Y', then
3547 a) Remove X and Y from the set FOUND_IN_SUBGRAPH.
3549 b) If the conditional is the only entry point to the sub-graph
3550 corresponding to the THEN_CLAUSE, recurse into it. On
3551 return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
3552 an ASSERT_EXPR is added for the corresponding variable.
3554 c) Repeat step (b) on the ELSE_CLAUSE.
3556 d) Mark X and Y in FOUND_IN_SUBGRAPH.
3565 In this case, an assertion on the THEN clause is useful to
3566 determine that 'a' is always 9 on that edge. However, an assertion
3567 on the ELSE clause would be unnecessary.
3569 4- If BB does not end in a conditional expression, then we recurse
3570 into BB's dominator children.
3572 At the end of the recursive traversal, every SSA name will have a
3573 list of locations where ASSERT_EXPRs should be added. When a new
3574 location for name N is found, it is registered by calling
3575 register_new_assert_for. That function keeps track of all the
3576 registered assertions to prevent adding unnecessary assertions.
3577 For instance, if a pointer P_4 is dereferenced more than once in a
3578 dominator tree, only the location dominating all the dereference of
3579 P_4 will receive an ASSERT_EXPR.
3581 If this function returns true, then it means that there are names
3582 for which we need to generate ASSERT_EXPRs. Those assertions are
3583 inserted by process_assert_insertions.
3585 TODO. Handle SWITCH_EXPR. */
3588 find_assert_locations (basic_block bb
)
3590 block_stmt_iterator si
;
3595 if (TEST_BIT (blocks_visited
, bb
->index
))
3598 SET_BIT (blocks_visited
, bb
->index
);
3600 need_assert
= false;
3602 /* Traverse all PHI nodes in BB marking used operands. */
3603 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3605 use_operand_p arg_p
;
3608 FOR_EACH_PHI_ARG (arg_p
, phi
, i
, SSA_OP_USE
)
3610 tree arg
= USE_FROM_PTR (arg_p
);
3611 if (TREE_CODE (arg
) == SSA_NAME
)
3613 gcc_assert (is_gimple_reg (PHI_RESULT (phi
)));
3614 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (arg
));
3619 /* Traverse all the statements in BB marking used names and looking
3620 for statements that may infer assertions for their used operands. */
3622 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
3627 stmt
= bsi_stmt (si
);
3629 /* See if we can derive an assertion for any of STMT's operands. */
3630 FOR_EACH_SSA_TREE_OPERAND (op
, stmt
, i
, SSA_OP_USE
)
3633 enum tree_code comp_code
;
3635 /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside
3636 the sub-graph of a conditional block, when we return from
3637 this recursive walk, our parent will use the
3638 FOUND_IN_SUBGRAPH bitset to determine if one of the
3639 operands it was looking for was present in the sub-graph. */
3640 SET_BIT (found_in_subgraph
, SSA_NAME_VERSION (op
));
3642 /* If OP is used in such a way that we can infer a value
3643 range for it, and we don't find a previous assertion for
3644 it, create a new assertion location node for OP. */
3645 if (infer_value_range (stmt
, op
, &comp_code
, &value
))
3647 /* If we are able to infer a nonzero value range for OP,
3648 then walk backwards through the use-def chain to see if OP
3649 was set via a typecast.
3651 If so, then we can also infer a nonzero value range
3652 for the operand of the NOP_EXPR. */
3653 if (comp_code
== NE_EXPR
&& integer_zerop (value
))
3656 tree def_stmt
= SSA_NAME_DEF_STMT (t
);
3658 while (TREE_CODE (def_stmt
) == MODIFY_EXPR
3659 && TREE_CODE (TREE_OPERAND (def_stmt
, 1)) == NOP_EXPR
3660 && TREE_CODE (TREE_OPERAND (TREE_OPERAND (def_stmt
, 1), 0)) == SSA_NAME
3661 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (def_stmt
, 1), 0))))
3663 t
= TREE_OPERAND (TREE_OPERAND (def_stmt
, 1), 0);
3664 def_stmt
= SSA_NAME_DEF_STMT (t
);
3666 /* Note we want to register the assert for the
3667 operand of the NOP_EXPR after SI, not after the
3669 if (! has_single_use (t
))
3671 register_new_assert_for (t
, comp_code
, value
,
3678 /* If OP is used only once, namely in this STMT, don't
3679 bother creating an ASSERT_EXPR for it. Such an
3680 ASSERT_EXPR would do nothing but increase compile time. */
3681 if (!has_single_use (op
))
3683 register_new_assert_for (op
, comp_code
, value
, bb
, NULL
, si
);
3689 /* Remember the last statement of the block. */
3693 /* If BB's last statement is a conditional expression
3694 involving integer operands, recurse into each of the sub-graphs
3695 rooted at BB to determine if we need to add ASSERT_EXPRs. */
3697 && TREE_CODE (last
) == COND_EXPR
3698 && !fp_predicate (COND_EXPR_COND (last
))
3699 && !ZERO_SSA_OPERANDS (last
, SSA_OP_USE
))
3700 need_assert
|= find_conditional_asserts (bb
);
3702 /* Recurse into the dominator children of BB. */
3703 for (son
= first_dom_son (CDI_DOMINATORS
, bb
);
3705 son
= next_dom_son (CDI_DOMINATORS
, son
))
3706 need_assert
|= find_assert_locations (son
);
3712 /* Create an ASSERT_EXPR for NAME and insert it in the location
3713 indicated by LOC. Return true if we made any edge insertions. */
3716 process_assert_insertions_for (tree name
, assert_locus_t loc
)
3718 /* Build the comparison expression NAME_i COMP_CODE VAL. */
3719 tree stmt
, cond
, assert_expr
;
3723 cond
= build2 (loc
->comp_code
, boolean_type_node
, name
, loc
->val
);
3724 assert_expr
= build_assert_expr_for (cond
, name
);
3728 /* We have been asked to insert the assertion on an edge. This
3729 is used only by COND_EXPR and SWITCH_EXPR assertions. */
3730 #if defined ENABLE_CHECKING
3731 gcc_assert (TREE_CODE (bsi_stmt (loc
->si
)) == COND_EXPR
3732 || TREE_CODE (bsi_stmt (loc
->si
)) == SWITCH_EXPR
);
3735 bsi_insert_on_edge (loc
->e
, assert_expr
);
3739 /* Otherwise, we can insert right after LOC->SI iff the
3740 statement must not be the last statement in the block. */
3741 stmt
= bsi_stmt (loc
->si
);
3742 if (!stmt_ends_bb_p (stmt
))
3744 bsi_insert_after (&loc
->si
, assert_expr
, BSI_SAME_STMT
);
3748 /* If STMT must be the last statement in BB, we can only insert new
3749 assertions on the non-abnormal edge out of BB. Note that since
3750 STMT is not control flow, there may only be one non-abnormal edge
3752 FOR_EACH_EDGE (e
, ei
, loc
->bb
->succs
)
3753 if (!(e
->flags
& EDGE_ABNORMAL
))
3755 bsi_insert_on_edge (e
, assert_expr
);
3763 /* Process all the insertions registered for every name N_i registered
3764 in NEED_ASSERT_FOR. The list of assertions to be inserted are
3765 found in ASSERTS_FOR[i]. */
3768 process_assert_insertions (void)
3772 bool update_edges_p
= false;
3773 int num_asserts
= 0;
3775 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3776 dump_all_asserts (dump_file
);
3778 EXECUTE_IF_SET_IN_BITMAP (need_assert_for
, 0, i
, bi
)
3780 assert_locus_t loc
= asserts_for
[i
];
3785 assert_locus_t next
= loc
->next
;
3786 update_edges_p
|= process_assert_insertions_for (ssa_name (i
), loc
);
3794 bsi_commit_edge_inserts ();
3796 if (dump_file
&& (dump_flags
& TDF_STATS
))
3797 fprintf (dump_file
, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n",
3802 /* Traverse the flowgraph looking for conditional jumps to insert range
3803 expressions. These range expressions are meant to provide information
3804 to optimizations that need to reason in terms of value ranges. They
3805 will not be expanded into RTL. For instance, given:
3814 this pass will transform the code into:
3820 x = ASSERT_EXPR <x, x < y>
3825 y = ASSERT_EXPR <y, x <= y>
3829 The idea is that once copy and constant propagation have run, other
3830 optimizations will be able to determine what ranges of values can 'x'
3831 take in different paths of the code, simply by checking the reaching
3832 definition of 'x'. */
3835 insert_range_assertions (void)
3841 found_in_subgraph
= sbitmap_alloc (num_ssa_names
);
3842 sbitmap_zero (found_in_subgraph
);
3844 blocks_visited
= sbitmap_alloc (last_basic_block
);
3845 sbitmap_zero (blocks_visited
);
3847 need_assert_for
= BITMAP_ALLOC (NULL
);
3848 asserts_for
= XNEWVEC (assert_locus_t
, num_ssa_names
);
3849 memset (asserts_for
, 0, num_ssa_names
* sizeof (assert_locus_t
));
3851 calculate_dominance_info (CDI_DOMINATORS
);
3853 update_ssa_p
= false;
3854 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
3855 if (find_assert_locations (e
->dest
))
3856 update_ssa_p
= true;
3860 process_assert_insertions ();
3861 update_ssa (TODO_update_ssa_no_phi
);
3864 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
3866 fprintf (dump_file
, "\nSSA form after inserting ASSERT_EXPRs\n");
3867 dump_function_to_file (current_function_decl
, dump_file
, dump_flags
);
3870 sbitmap_free (found_in_subgraph
);
3872 BITMAP_FREE (need_assert_for
);
3876 /* Convert range assertion expressions into the implied copies and
3877 copy propagate away the copies. Doing the trivial copy propagation
3878 here avoids the need to run the full copy propagation pass after
3881 FIXME, this will eventually lead to copy propagation removing the
3882 names that had useful range information attached to them. For
3883 instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
3884 then N_i will have the range [3, +INF].
3886 However, by converting the assertion into the implied copy
3887 operation N_i = N_j, we will then copy-propagate N_j into the uses
3888 of N_i and lose the range information. We may want to hold on to
3889 ASSERT_EXPRs a little while longer as the ranges could be used in
3890 things like jump threading.
3892 The problem with keeping ASSERT_EXPRs around is that passes after
3893 VRP need to handle them appropriately.
3895 Another approach would be to make the range information a first
3896 class property of the SSA_NAME so that it can be queried from
3897 any pass. This is made somewhat more complex by the need for
3898 multiple ranges to be associated with one SSA_NAME. */
3901 remove_range_assertions (void)
3904 block_stmt_iterator si
;
3906 /* Note that the BSI iterator bump happens at the bottom of the
3907 loop and no bump is necessary if we're removing the statement
3908 referenced by the current BSI. */
3910 for (si
= bsi_start (bb
); !bsi_end_p (si
);)
3912 tree stmt
= bsi_stmt (si
);
3915 if (TREE_CODE (stmt
) == MODIFY_EXPR
3916 && TREE_CODE (TREE_OPERAND (stmt
, 1)) == ASSERT_EXPR
)
3918 tree rhs
= TREE_OPERAND (stmt
, 1), var
;
3919 tree cond
= fold (ASSERT_EXPR_COND (rhs
));
3920 use_operand_p use_p
;
3921 imm_use_iterator iter
;
3923 gcc_assert (cond
!= boolean_false_node
);
3925 /* Propagate the RHS into every use of the LHS. */
3926 var
= ASSERT_EXPR_VAR (rhs
);
3927 FOR_EACH_IMM_USE_STMT (use_stmt
, iter
, TREE_OPERAND (stmt
, 0))
3928 FOR_EACH_IMM_USE_ON_STMT (use_p
, iter
)
3930 SET_USE (use_p
, var
);
3931 gcc_assert (TREE_CODE (var
) == SSA_NAME
);
3934 /* And finally, remove the copy, it is not needed. */
3935 bsi_remove (&si
, true);
3941 sbitmap_free (blocks_visited
);
3945 /* Return true if STMT is interesting for VRP. */
3948 stmt_interesting_for_vrp (tree stmt
)
3950 if (TREE_CODE (stmt
) == PHI_NODE
3951 && is_gimple_reg (PHI_RESULT (stmt
))
3952 && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))
3953 || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt
)))))
3955 else if (TREE_CODE (stmt
) == MODIFY_EXPR
)
3957 tree lhs
= TREE_OPERAND (stmt
, 0);
3958 tree rhs
= TREE_OPERAND (stmt
, 1);
3960 /* In general, assignments with virtual operands are not useful
3961 for deriving ranges, with the obvious exception of calls to
3962 builtin functions. */
3963 if (TREE_CODE (lhs
) == SSA_NAME
3964 && (INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
3965 || POINTER_TYPE_P (TREE_TYPE (lhs
)))
3966 && ((TREE_CODE (rhs
) == CALL_EXPR
3967 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == ADDR_EXPR
3968 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0))
3969 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0)))
3970 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
)))
3973 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
3980 /* Initialize local data structures for VRP. */
3983 vrp_initialize (void)
3987 vr_value
= XNEWVEC (value_range_t
*, num_ssa_names
);
3988 memset (vr_value
, 0, num_ssa_names
* sizeof (value_range_t
*));
3992 block_stmt_iterator si
;
3995 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
3997 if (!stmt_interesting_for_vrp (phi
))
3999 tree lhs
= PHI_RESULT (phi
);
4000 set_value_range_to_varying (get_value_range (lhs
));
4001 DONT_SIMULATE_AGAIN (phi
) = true;
4004 DONT_SIMULATE_AGAIN (phi
) = false;
4007 for (si
= bsi_start (bb
); !bsi_end_p (si
); bsi_next (&si
))
4009 tree stmt
= bsi_stmt (si
);
4011 if (!stmt_interesting_for_vrp (stmt
))
4015 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, i
, SSA_OP_DEF
)
4016 set_value_range_to_varying (get_value_range (def
));
4017 DONT_SIMULATE_AGAIN (stmt
) = true;
4021 DONT_SIMULATE_AGAIN (stmt
) = false;
4028 /* Visit assignment STMT. If it produces an interesting range, record
4029 the SSA name in *OUTPUT_P. */
4031 static enum ssa_prop_result
4032 vrp_visit_assignment (tree stmt
, tree
*output_p
)
4037 lhs
= TREE_OPERAND (stmt
, 0);
4038 rhs
= TREE_OPERAND (stmt
, 1);
4040 /* We only keep track of ranges in integral and pointer types. */
4041 if (TREE_CODE (lhs
) == SSA_NAME
4042 && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
4043 /* It is valid to have NULL MIN/MAX values on a type. See
4044 build_range_type. */
4045 && TYPE_MIN_VALUE (TREE_TYPE (lhs
))
4046 && TYPE_MAX_VALUE (TREE_TYPE (lhs
)))
4047 || POINTER_TYPE_P (TREE_TYPE (lhs
))))
4050 value_range_t new_vr
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
4052 extract_range_from_expr (&new_vr
, rhs
);
4054 /* If STMT is inside a loop, we may be able to know something
4055 else about the range of LHS by examining scalar evolution
4057 if (current_loops
&& (l
= loop_containing_stmt (stmt
)))
4058 adjust_range_with_scev (&new_vr
, l
, stmt
, lhs
);
4060 if (update_value_range (lhs
, &new_vr
))
4064 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4066 fprintf (dump_file
, "Found new range for ");
4067 print_generic_expr (dump_file
, lhs
, 0);
4068 fprintf (dump_file
, ": ");
4069 dump_value_range (dump_file
, &new_vr
);
4070 fprintf (dump_file
, "\n\n");
4073 if (new_vr
.type
== VR_VARYING
)
4074 return SSA_PROP_VARYING
;
4076 return SSA_PROP_INTERESTING
;
4079 return SSA_PROP_NOT_INTERESTING
;
4082 /* Every other statement produces no useful ranges. */
4083 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
4084 set_value_range_to_varying (get_value_range (def
));
4086 return SSA_PROP_VARYING
;
4090 /* Compare all the value ranges for names equivalent to VAR with VAL
4091 using comparison code COMP. Return the same value returned by
4092 compare_range_with_value, including the setting of
4093 *STRICT_OVERFLOW_P. */
4096 compare_name_with_value (enum tree_code comp
, tree var
, tree val
,
4097 bool *strict_overflow_p
)
4103 int used_strict_overflow
;
4105 t
= retval
= NULL_TREE
;
4107 /* Get the set of equivalences for VAR. */
4108 e
= get_value_range (var
)->equiv
;
4110 /* Add VAR to its own set of equivalences so that VAR's value range
4111 is processed by this loop (otherwise, we would have to replicate
4112 the body of the loop just to check VAR's value range). */
4113 bitmap_set_bit (e
, SSA_NAME_VERSION (var
));
4115 /* Start at -1. Set it to 0 if we do a comparison without relying
4116 on overflow, or 1 if all comparisons rely on overflow. */
4117 used_strict_overflow
= -1;
4119 EXECUTE_IF_SET_IN_BITMAP (e
, 0, i
, bi
)
4123 value_range_t equiv_vr
= *(vr_value
[i
]);
4125 /* If name N_i does not have a valid range, use N_i as its own
4126 range. This allows us to compare against names that may
4127 have N_i in their ranges. */
4128 if (equiv_vr
.type
== VR_VARYING
|| equiv_vr
.type
== VR_UNDEFINED
)
4130 equiv_vr
.type
= VR_RANGE
;
4131 equiv_vr
.min
= ssa_name (i
);
4132 equiv_vr
.max
= ssa_name (i
);
4136 t
= compare_range_with_value (comp
, &equiv_vr
, val
, &sop
);
4139 /* If we get different answers from different members
4140 of the equivalence set this check must be in a dead
4141 code region. Folding it to a trap representation
4142 would be correct here. For now just return don't-know. */
4152 used_strict_overflow
= 0;
4153 else if (used_strict_overflow
< 0)
4154 used_strict_overflow
= 1;
4158 /* Remove VAR from its own equivalence set. */
4159 bitmap_clear_bit (e
, SSA_NAME_VERSION (var
));
4163 if (used_strict_overflow
> 0)
4164 *strict_overflow_p
= true;
4168 /* We couldn't find a non-NULL value for the predicate. */
4173 /* Given a comparison code COMP and names N1 and N2, compare all the
4174 ranges equivalent to N1 against all the ranges equivalent to N2
4175 to determine the value of N1 COMP N2. Return the same value
4176 returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate
4177 whether we relied on an overflow infinity in the comparison. */
4181 compare_names (enum tree_code comp
, tree n1
, tree n2
,
4182 bool *strict_overflow_p
)
4186 bitmap_iterator bi1
, bi2
;
4188 int used_strict_overflow
;
4190 /* Compare the ranges of every name equivalent to N1 against the
4191 ranges of every name equivalent to N2. */
4192 e1
= get_value_range (n1
)->equiv
;
4193 e2
= get_value_range (n2
)->equiv
;
4195 /* Add N1 and N2 to their own set of equivalences to avoid
4196 duplicating the body of the loop just to check N1 and N2
4198 bitmap_set_bit (e1
, SSA_NAME_VERSION (n1
));
4199 bitmap_set_bit (e2
, SSA_NAME_VERSION (n2
));
4201 /* If the equivalence sets have a common intersection, then the two
4202 names can be compared without checking their ranges. */
4203 if (bitmap_intersect_p (e1
, e2
))
4205 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
4206 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
4208 return (comp
== EQ_EXPR
|| comp
== GE_EXPR
|| comp
== LE_EXPR
)
4210 : boolean_false_node
;
4213 /* Start at -1. Set it to 0 if we do a comparison without relying
4214 on overflow, or 1 if all comparisons rely on overflow. */
4215 used_strict_overflow
= -1;
4217 /* Otherwise, compare all the equivalent ranges. First, add N1 and
4218 N2 to their own set of equivalences to avoid duplicating the body
4219 of the loop just to check N1 and N2 ranges. */
4220 EXECUTE_IF_SET_IN_BITMAP (e1
, 0, i1
, bi1
)
4222 value_range_t vr1
= *(vr_value
[i1
]);
4224 /* If the range is VARYING or UNDEFINED, use the name itself. */
4225 if (vr1
.type
== VR_VARYING
|| vr1
.type
== VR_UNDEFINED
)
4227 vr1
.type
= VR_RANGE
;
4228 vr1
.min
= ssa_name (i1
);
4229 vr1
.max
= ssa_name (i1
);
4232 t
= retval
= NULL_TREE
;
4233 EXECUTE_IF_SET_IN_BITMAP (e2
, 0, i2
, bi2
)
4237 value_range_t vr2
= *(vr_value
[i2
]);
4239 if (vr2
.type
== VR_VARYING
|| vr2
.type
== VR_UNDEFINED
)
4241 vr2
.type
= VR_RANGE
;
4242 vr2
.min
= ssa_name (i2
);
4243 vr2
.max
= ssa_name (i2
);
4246 t
= compare_ranges (comp
, &vr1
, &vr2
, &sop
);
4249 /* If we get different answers from different members
4250 of the equivalence set this check must be in a dead
4251 code region. Folding it to a trap representation
4252 would be correct here. For now just return don't-know. */
4256 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
4257 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
4263 used_strict_overflow
= 0;
4264 else if (used_strict_overflow
< 0)
4265 used_strict_overflow
= 1;
4271 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
4272 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
4273 if (used_strict_overflow
> 0)
4274 *strict_overflow_p
= true;
4279 /* None of the equivalent ranges are useful in computing this
4281 bitmap_clear_bit (e1
, SSA_NAME_VERSION (n1
));
4282 bitmap_clear_bit (e2
, SSA_NAME_VERSION (n2
));
4287 /* Given a conditional predicate COND, try to determine if COND yields
4288 true or false based on the value ranges of its operands. Return
4289 BOOLEAN_TRUE_NODE if the conditional always evaluates to true,
4290 BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and,
4291 NULL if the conditional cannot be evaluated at compile time.
4293 If USE_EQUIV_P is true, the ranges of all the names equivalent with
4294 the operands in COND are used when trying to compute its value.
4295 This is only used during final substitution. During propagation,
4296 we only check the range of each variable and not its equivalents.
4298 Set *STRICT_OVERFLOW_P to indicate whether we relied on an overflow
4299 infinity to produce the result. */
4302 vrp_evaluate_conditional_warnv (tree cond
, bool use_equiv_p
,
4303 bool *strict_overflow_p
)
4305 gcc_assert (TREE_CODE (cond
) == SSA_NAME
4306 || TREE_CODE_CLASS (TREE_CODE (cond
)) == tcc_comparison
);
4308 if (TREE_CODE (cond
) == SSA_NAME
)
4314 retval
= compare_name_with_value (NE_EXPR
, cond
, boolean_false_node
,
4318 value_range_t
*vr
= get_value_range (cond
);
4319 retval
= compare_range_with_value (NE_EXPR
, vr
, boolean_false_node
,
4323 /* If COND has a known boolean range, return it. */
4327 /* Otherwise, if COND has a symbolic range of exactly one value,
4329 vr
= get_value_range (cond
);
4330 if (vr
->type
== VR_RANGE
&& vr
->min
== vr
->max
)
4335 tree op0
= TREE_OPERAND (cond
, 0);
4336 tree op1
= TREE_OPERAND (cond
, 1);
4338 /* We only deal with integral and pointer types. */
4339 if (!INTEGRAL_TYPE_P (TREE_TYPE (op0
))
4340 && !POINTER_TYPE_P (TREE_TYPE (op0
)))
4345 if (TREE_CODE (op0
) == SSA_NAME
&& TREE_CODE (op1
) == SSA_NAME
)
4346 return compare_names (TREE_CODE (cond
), op0
, op1
,
4348 else if (TREE_CODE (op0
) == SSA_NAME
)
4349 return compare_name_with_value (TREE_CODE (cond
), op0
, op1
,
4351 else if (TREE_CODE (op1
) == SSA_NAME
)
4352 return (compare_name_with_value
4353 (swap_tree_comparison (TREE_CODE (cond
)), op1
, op0
,
4354 strict_overflow_p
));
4358 value_range_t
*vr0
, *vr1
;
4360 vr0
= (TREE_CODE (op0
) == SSA_NAME
) ? get_value_range (op0
) : NULL
;
4361 vr1
= (TREE_CODE (op1
) == SSA_NAME
) ? get_value_range (op1
) : NULL
;
4364 return compare_ranges (TREE_CODE (cond
), vr0
, vr1
,
4366 else if (vr0
&& vr1
== NULL
)
4367 return compare_range_with_value (TREE_CODE (cond
), vr0
, op1
,
4369 else if (vr0
== NULL
&& vr1
)
4370 return (compare_range_with_value
4371 (swap_tree_comparison (TREE_CODE (cond
)), vr1
, op0
,
4372 strict_overflow_p
));
4376 /* Anything else cannot be computed statically. */
4380 /* Given COND within STMT, try to simplify it based on value range
4381 information. Return NULL if the conditional can not be evaluated.
4382 The ranges of all the names equivalent with the operands in COND
4383 will be used when trying to compute the value. If the result is
4384 based on undefined signed overflow, issue a warning if
4388 vrp_evaluate_conditional (tree cond
, tree stmt
)
4394 ret
= vrp_evaluate_conditional_warnv (cond
, true, &sop
);
4398 enum warn_strict_overflow_code wc
;
4399 const char* warnmsg
;
4401 if (is_gimple_min_invariant (ret
))
4403 wc
= WARN_STRICT_OVERFLOW_CONDITIONAL
;
4404 warnmsg
= G_("assuming signed overflow does not occur when "
4405 "simplifying conditional to constant");
4409 wc
= WARN_STRICT_OVERFLOW_COMPARISON
;
4410 warnmsg
= G_("assuming signed overflow does not occur when "
4411 "simplifying conditional");
4414 if (issue_strict_overflow_warning (wc
))
4418 if (!EXPR_HAS_LOCATION (stmt
))
4419 locus
= input_location
;
4421 locus
= EXPR_LOCATION (stmt
);
4422 warning (OPT_Wstrict_overflow
, "%H%s", &locus
, warnmsg
);
4430 /* Visit conditional statement STMT. If we can determine which edge
4431 will be taken out of STMT's basic block, record it in
4432 *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return
4433 SSA_PROP_VARYING. */
4435 static enum ssa_prop_result
4436 vrp_visit_cond_stmt (tree stmt
, edge
*taken_edge_p
)
4441 *taken_edge_p
= NULL
;
4443 /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to
4444 add ASSERT_EXPRs for them. */
4445 if (TREE_CODE (stmt
) == SWITCH_EXPR
)
4446 return SSA_PROP_VARYING
;
4448 cond
= COND_EXPR_COND (stmt
);
4450 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4455 fprintf (dump_file
, "\nVisiting conditional with predicate: ");
4456 print_generic_expr (dump_file
, cond
, 0);
4457 fprintf (dump_file
, "\nWith known ranges\n");
4459 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, i
, SSA_OP_USE
)
4461 fprintf (dump_file
, "\t");
4462 print_generic_expr (dump_file
, use
, 0);
4463 fprintf (dump_file
, ": ");
4464 dump_value_range (dump_file
, vr_value
[SSA_NAME_VERSION (use
)]);
4467 fprintf (dump_file
, "\n");
4470 /* Compute the value of the predicate COND by checking the known
4471 ranges of each of its operands.
4473 Note that we cannot evaluate all the equivalent ranges here
4474 because those ranges may not yet be final and with the current
4475 propagation strategy, we cannot determine when the value ranges
4476 of the names in the equivalence set have changed.
4478 For instance, given the following code fragment
4482 i_14 = ASSERT_EXPR <i_5, i_5 != 0>
4486 Assume that on the first visit to i_14, i_5 has the temporary
4487 range [8, 8] because the second argument to the PHI function is
4488 not yet executable. We derive the range ~[0, 0] for i_14 and the
4489 equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
4490 the first time, since i_14 is equivalent to the range [8, 8], we
4491 determine that the predicate is always false.
4493 On the next round of propagation, i_13 is determined to be
4494 VARYING, which causes i_5 to drop down to VARYING. So, another
4495 visit to i_14 is scheduled. In this second visit, we compute the
4496 exact same range and equivalence set for i_14, namely ~[0, 0] and
4497 { i_5 }. But we did not have the previous range for i_5
4498 registered, so vrp_visit_assignment thinks that the range for
4499 i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
4500 is not visited again, which stops propagation from visiting
4501 statements in the THEN clause of that if().
4503 To properly fix this we would need to keep the previous range
4504 value for the names in the equivalence set. This way we would've
4505 discovered that from one visit to the other i_5 changed from
4506 range [8, 8] to VR_VARYING.
4508 However, fixing this apparent limitation may not be worth the
4509 additional checking. Testing on several code bases (GCC, DLV,
4510 MICO, TRAMP3D and SPEC2000) showed that doing this results in
4511 4 more predicates folded in SPEC. */
4513 val
= vrp_evaluate_conditional_warnv (cond
, false, &sop
);
4517 *taken_edge_p
= find_taken_edge (bb_for_stmt (stmt
), val
);
4520 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4522 "\nIgnoring predicate evaluation because "
4523 "it assumes that signed overflow is undefined");
4528 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4530 fprintf (dump_file
, "\nPredicate evaluates to: ");
4531 if (val
== NULL_TREE
)
4532 fprintf (dump_file
, "DON'T KNOW\n");
4534 print_generic_stmt (dump_file
, val
, 0);
4537 return (*taken_edge_p
) ? SSA_PROP_INTERESTING
: SSA_PROP_VARYING
;
4541 /* Evaluate statement STMT. If the statement produces a useful range,
4542 return SSA_PROP_INTERESTING and record the SSA name with the
4543 interesting range into *OUTPUT_P.
4545 If STMT is a conditional branch and we can determine its truth
4546 value, the taken edge is recorded in *TAKEN_EDGE_P.
4548 If STMT produces a varying value, return SSA_PROP_VARYING. */
4550 static enum ssa_prop_result
4551 vrp_visit_stmt (tree stmt
, edge
*taken_edge_p
, tree
*output_p
)
4557 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4559 fprintf (dump_file
, "\nVisiting statement:\n");
4560 print_generic_stmt (dump_file
, stmt
, dump_flags
);
4561 fprintf (dump_file
, "\n");
4564 ann
= stmt_ann (stmt
);
4565 if (TREE_CODE (stmt
) == MODIFY_EXPR
)
4567 tree rhs
= TREE_OPERAND (stmt
, 1);
4569 /* In general, assignments with virtual operands are not useful
4570 for deriving ranges, with the obvious exception of calls to
4571 builtin functions. */
4572 if ((TREE_CODE (rhs
) == CALL_EXPR
4573 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == ADDR_EXPR
4574 && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0))
4575 && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0)))
4576 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
4577 return vrp_visit_assignment (stmt
, output_p
);
4579 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
4580 return vrp_visit_cond_stmt (stmt
, taken_edge_p
);
4582 /* All other statements produce nothing of interest for VRP, so mark
4583 their outputs varying and prevent further simulation. */
4584 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
4585 set_value_range_to_varying (get_value_range (def
));
4587 return SSA_PROP_VARYING
;
4591 /* Meet operation for value ranges. Given two value ranges VR0 and
4592 VR1, store in VR0 the result of meeting VR0 and VR1.
4594 The meeting rules are as follows:
4596 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING.
4598 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the
4599 union of VR0 and VR1. */
4602 vrp_meet (value_range_t
*vr0
, value_range_t
*vr1
)
4604 if (vr0
->type
== VR_UNDEFINED
)
4606 copy_value_range (vr0
, vr1
);
4610 if (vr1
->type
== VR_UNDEFINED
)
4612 /* Nothing to do. VR0 already has the resulting range. */
4616 if (vr0
->type
== VR_VARYING
)
4618 /* Nothing to do. VR0 already has the resulting range. */
4622 if (vr1
->type
== VR_VARYING
)
4624 set_value_range_to_varying (vr0
);
4628 if (vr0
->type
== VR_RANGE
&& vr1
->type
== VR_RANGE
)
4630 /* If VR0 and VR1 have a non-empty intersection, compute the
4631 union of both ranges. */
4632 if (value_ranges_intersect_p (vr0
, vr1
))
4637 /* The lower limit of the new range is the minimum of the
4638 two ranges. If they cannot be compared, the result is
4640 cmp
= compare_values (vr0
->min
, vr1
->min
);
4641 if (cmp
== 0 || cmp
== 1)
4647 set_value_range_to_varying (vr0
);
4651 /* Similarly, the upper limit of the new range is the
4652 maximum of the two ranges. If they cannot be compared,
4653 the result is VARYING. */
4654 cmp
= compare_values (vr0
->max
, vr1
->max
);
4655 if (cmp
== 0 || cmp
== -1)
4661 set_value_range_to_varying (vr0
);
4665 /* Check for useless ranges. */
4666 if (INTEGRAL_TYPE_P (TREE_TYPE (min
))
4667 && ((vrp_val_is_min (min
) || is_overflow_infinity (min
))
4668 && (vrp_val_is_max (max
) || is_overflow_infinity (max
))))
4670 set_value_range_to_varying (vr0
);
4674 /* The resulting set of equivalences is the intersection of
4676 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
4677 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
4678 else if (vr0
->equiv
&& !vr1
->equiv
)
4679 bitmap_clear (vr0
->equiv
);
4681 set_value_range (vr0
, vr0
->type
, min
, max
, vr0
->equiv
);
4686 else if (vr0
->type
== VR_ANTI_RANGE
&& vr1
->type
== VR_ANTI_RANGE
)
4688 /* Two anti-ranges meet only if they are both identical. */
4689 if (compare_values (vr0
->min
, vr1
->min
) == 0
4690 && compare_values (vr0
->max
, vr1
->max
) == 0
4691 && compare_values (vr0
->min
, vr0
->max
) == 0)
4693 /* The resulting set of equivalences is the intersection of
4695 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
4696 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
4697 else if (vr0
->equiv
&& !vr1
->equiv
)
4698 bitmap_clear (vr0
->equiv
);
4703 else if (vr0
->type
== VR_ANTI_RANGE
|| vr1
->type
== VR_ANTI_RANGE
)
4705 /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4]
4706 meet only if the ranges have an empty intersection. The
4707 result of the meet operation is the anti-range. */
4708 if (!symbolic_range_p (vr0
)
4709 && !symbolic_range_p (vr1
)
4710 && !value_ranges_intersect_p (vr0
, vr1
))
4712 /* Copy most of VR1 into VR0. Don't copy VR1's equivalence
4713 set. We need to compute the intersection of the two
4714 equivalence sets. */
4715 if (vr1
->type
== VR_ANTI_RANGE
)
4716 set_value_range (vr0
, vr1
->type
, vr1
->min
, vr1
->max
, vr0
->equiv
);
4718 /* The resulting set of equivalences is the intersection of
4720 if (vr0
->equiv
&& vr1
->equiv
&& vr0
->equiv
!= vr1
->equiv
)
4721 bitmap_and_into (vr0
->equiv
, vr1
->equiv
);
4722 else if (vr0
->equiv
&& !vr1
->equiv
)
4723 bitmap_clear (vr0
->equiv
);
4734 /* The two range VR0 and VR1 do not meet. Before giving up and
4735 setting the result to VARYING, see if we can at least derive a
4736 useful anti-range. FIXME, all this nonsense about distinguishing
4737 anti-ranges from ranges is necessary because of the odd
4738 semantics of range_includes_zero_p and friends. */
4739 if (!symbolic_range_p (vr0
)
4740 && ((vr0
->type
== VR_RANGE
&& !range_includes_zero_p (vr0
))
4741 || (vr0
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr0
)))
4742 && !symbolic_range_p (vr1
)
4743 && ((vr1
->type
== VR_RANGE
&& !range_includes_zero_p (vr1
))
4744 || (vr1
->type
== VR_ANTI_RANGE
&& range_includes_zero_p (vr1
))))
4746 set_value_range_to_nonnull (vr0
, TREE_TYPE (vr0
->min
));
4748 /* Since this meet operation did not result from the meeting of
4749 two equivalent names, VR0 cannot have any equivalences. */
4751 bitmap_clear (vr0
->equiv
);
4754 set_value_range_to_varying (vr0
);
4758 /* Visit all arguments for PHI node PHI that flow through executable
4759 edges. If a valid value range can be derived from all the incoming
4760 value ranges, set a new range for the LHS of PHI. */
4762 static enum ssa_prop_result
4763 vrp_visit_phi_node (tree phi
)
4766 tree lhs
= PHI_RESULT (phi
);
4767 value_range_t
*lhs_vr
= get_value_range (lhs
);
4768 value_range_t vr_result
= { VR_UNDEFINED
, NULL_TREE
, NULL_TREE
, NULL
};
4770 copy_value_range (&vr_result
, lhs_vr
);
4772 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4774 fprintf (dump_file
, "\nVisiting PHI node: ");
4775 print_generic_expr (dump_file
, phi
, dump_flags
);
4778 for (i
= 0; i
< PHI_NUM_ARGS (phi
); i
++)
4780 edge e
= PHI_ARG_EDGE (phi
, i
);
4782 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4785 "\n Argument #%d (%d -> %d %sexecutable)\n",
4786 i
, e
->src
->index
, e
->dest
->index
,
4787 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
4790 if (e
->flags
& EDGE_EXECUTABLE
)
4792 tree arg
= PHI_ARG_DEF (phi
, i
);
4793 value_range_t vr_arg
;
4795 if (TREE_CODE (arg
) == SSA_NAME
)
4796 vr_arg
= *(get_value_range (arg
));
4799 if (is_overflow_infinity (arg
))
4801 arg
= copy_node (arg
);
4802 TREE_OVERFLOW (arg
) = 0;
4805 vr_arg
.type
= VR_RANGE
;
4808 vr_arg
.equiv
= NULL
;
4811 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
4813 fprintf (dump_file
, "\t");
4814 print_generic_expr (dump_file
, arg
, dump_flags
);
4815 fprintf (dump_file
, "\n\tValue: ");
4816 dump_value_range (dump_file
, &vr_arg
);
4817 fprintf (dump_file
, "\n");
4820 vrp_meet (&vr_result
, &vr_arg
);
4822 if (vr_result
.type
== VR_VARYING
)
4827 if (vr_result
.type
== VR_VARYING
)
4830 /* To prevent infinite iterations in the algorithm, derive ranges
4831 when the new value is slightly bigger or smaller than the
4833 if (lhs_vr
->type
== VR_RANGE
&& vr_result
.type
== VR_RANGE
)
4835 if (!POINTER_TYPE_P (TREE_TYPE (lhs
)))
4837 int cmp_min
= compare_values (lhs_vr
->min
, vr_result
.min
);
4838 int cmp_max
= compare_values (lhs_vr
->max
, vr_result
.max
);
4840 /* If the new minimum is smaller or larger than the previous
4841 one, go all the way to -INF. In the first case, to avoid
4842 iterating millions of times to reach -INF, and in the
4843 other case to avoid infinite bouncing between different
4845 if (cmp_min
> 0 || cmp_min
< 0)
4847 /* If we will end up with a (-INF, +INF) range, set it
4849 if (vrp_val_is_max (vr_result
.max
))
4852 if (!needs_overflow_infinity (TREE_TYPE (vr_result
.min
))
4853 || !vrp_var_may_overflow (lhs
, phi
))
4854 vr_result
.min
= TYPE_MIN_VALUE (TREE_TYPE (vr_result
.min
));
4855 else if (supports_overflow_infinity (TREE_TYPE (vr_result
.min
)))
4857 negative_overflow_infinity (TREE_TYPE (vr_result
.min
));
4862 /* Similarly, if the new maximum is smaller or larger than
4863 the previous one, go all the way to +INF. */
4864 if (cmp_max
< 0 || cmp_max
> 0)
4866 /* If we will end up with a (-INF, +INF) range, set it
4868 if (vrp_val_is_min (vr_result
.min
))
4871 if (!needs_overflow_infinity (TREE_TYPE (vr_result
.max
))
4872 || !vrp_var_may_overflow (lhs
, phi
))
4873 vr_result
.max
= TYPE_MAX_VALUE (TREE_TYPE (vr_result
.max
));
4874 else if (supports_overflow_infinity (TREE_TYPE (vr_result
.max
)))
4876 positive_overflow_infinity (TREE_TYPE (vr_result
.max
));
4883 /* If the new range is different than the previous value, keep
4885 if (update_value_range (lhs
, &vr_result
))
4886 return SSA_PROP_INTERESTING
;
4888 /* Nothing changed, don't add outgoing edges. */
4889 return SSA_PROP_NOT_INTERESTING
;
4891 /* No match found. Set the LHS to VARYING. */
4893 set_value_range_to_varying (lhs_vr
);
4894 return SSA_PROP_VARYING
;
4897 /* Simplify a division or modulo operator to a right shift or
4898 bitwise and if the first operand is unsigned or is greater
4899 than zero and the second operand is an exact power of two. */
4902 simplify_div_or_mod_using_ranges (tree stmt
, tree rhs
, enum tree_code rhs_code
)
4905 tree op
= TREE_OPERAND (rhs
, 0);
4906 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
4908 if (TYPE_UNSIGNED (TREE_TYPE (op
)))
4910 val
= integer_one_node
;
4916 val
= compare_range_with_value (GT_EXPR
, vr
, integer_zero_node
, &sop
);
4920 && integer_onep (val
)
4921 && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC
))
4925 if (!EXPR_HAS_LOCATION (stmt
))
4926 locus
= input_location
;
4928 locus
= EXPR_LOCATION (stmt
);
4929 warning (OPT_Wstrict_overflow
,
4930 ("%Hassuming signed overflow does not occur when "
4931 "simplifying / or %% to >> or &"),
4936 if (val
&& integer_onep (val
))
4939 tree op0
= TREE_OPERAND (rhs
, 0);
4940 tree op1
= TREE_OPERAND (rhs
, 1);
4942 if (rhs_code
== TRUNC_DIV_EXPR
)
4944 t
= build_int_cst (NULL_TREE
, tree_log2 (op1
));
4945 t
= build2 (RSHIFT_EXPR
, TREE_TYPE (op0
), op0
, t
);
4949 t
= build_int_cst (TREE_TYPE (op1
), 1);
4950 t
= int_const_binop (MINUS_EXPR
, op1
, t
, 0);
4951 t
= fold_convert (TREE_TYPE (op0
), t
);
4952 t
= build2 (BIT_AND_EXPR
, TREE_TYPE (op0
), op0
, t
);
4955 TREE_OPERAND (stmt
, 1) = t
;
4960 /* If the operand to an ABS_EXPR is >= 0, then eliminate the
4961 ABS_EXPR. If the operand is <= 0, then simplify the
4962 ABS_EXPR into a NEGATE_EXPR. */
4965 simplify_abs_using_ranges (tree stmt
, tree rhs
)
4968 tree op
= TREE_OPERAND (rhs
, 0);
4969 tree type
= TREE_TYPE (op
);
4970 value_range_t
*vr
= get_value_range (TREE_OPERAND (rhs
, 0));
4972 if (TYPE_UNSIGNED (type
))
4974 val
= integer_zero_node
;
4980 val
= compare_range_with_value (LE_EXPR
, vr
, integer_zero_node
, &sop
);
4984 val
= compare_range_with_value (GE_EXPR
, vr
, integer_zero_node
,
4989 if (integer_zerop (val
))
4990 val
= integer_one_node
;
4991 else if (integer_onep (val
))
4992 val
= integer_zero_node
;
4997 && (integer_onep (val
) || integer_zerop (val
)))
5001 if (sop
&& issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC
))
5005 if (!EXPR_HAS_LOCATION (stmt
))
5006 locus
= input_location
;
5008 locus
= EXPR_LOCATION (stmt
);
5009 warning (OPT_Wstrict_overflow
,
5010 ("%Hassuming signed overflow does not occur when "
5011 "simplifying abs (X) to X or -X"),
5015 if (integer_onep (val
))
5016 t
= build1 (NEGATE_EXPR
, TREE_TYPE (op
), op
);
5020 TREE_OPERAND (stmt
, 1) = t
;
5026 /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has
5027 a known value range VR.
5029 If there is one and only one value which will satisfy the
5030 conditional, then return that value. Else return NULL. */
5033 test_for_singularity (enum tree_code cond_code
, tree op0
,
5034 tree op1
, value_range_t
*vr
)
5039 /* Extract minimum/maximum values which satisfy the
5040 the conditional as it was written. */
5041 if (cond_code
== LE_EXPR
|| cond_code
== LT_EXPR
)
5043 /* This should not be negative infinity; there is no overflow
5045 min
= TYPE_MIN_VALUE (TREE_TYPE (op0
));
5048 if (cond_code
== LT_EXPR
&& !is_overflow_infinity (max
))
5050 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
5051 max
= fold_build2 (MINUS_EXPR
, TREE_TYPE (op0
), max
, one
);
5053 TREE_NO_WARNING (max
) = 1;
5056 else if (cond_code
== GE_EXPR
|| cond_code
== GT_EXPR
)
5058 /* This should not be positive infinity; there is no overflow
5060 max
= TYPE_MAX_VALUE (TREE_TYPE (op0
));
5063 if (cond_code
== GT_EXPR
&& !is_overflow_infinity (min
))
5065 tree one
= build_int_cst (TREE_TYPE (op0
), 1);
5066 min
= fold_build2 (PLUS_EXPR
, TREE_TYPE (op0
), min
, one
);
5068 TREE_NO_WARNING (min
) = 1;
5072 /* Now refine the minimum and maximum values using any
5073 value range information we have for op0. */
5076 if (compare_values (vr
->min
, min
) == -1)
5080 if (compare_values (vr
->max
, max
) == 1)
5085 /* If the new min/max values have converged to a single value,
5086 then there is only one value which can satisfy the condition,
5087 return that value. */
5088 if (operand_equal_p (min
, max
, 0) && is_gimple_min_invariant (min
))
5094 /* Simplify a conditional using a relational operator to an equality
5095 test if the range information indicates only one value can satisfy
5096 the original conditional. */
5099 simplify_cond_using_ranges (tree stmt
)
5101 tree cond
= COND_EXPR_COND (stmt
);
5102 tree op0
= TREE_OPERAND (cond
, 0);
5103 tree op1
= TREE_OPERAND (cond
, 1);
5104 enum tree_code cond_code
= TREE_CODE (cond
);
5106 if (cond_code
!= NE_EXPR
5107 && cond_code
!= EQ_EXPR
5108 && TREE_CODE (op0
) == SSA_NAME
5109 && INTEGRAL_TYPE_P (TREE_TYPE (op0
))
5110 && is_gimple_min_invariant (op1
))
5112 value_range_t
*vr
= get_value_range (op0
);
5114 /* If we have range information for OP0, then we might be
5115 able to simplify this conditional. */
5116 if (vr
->type
== VR_RANGE
)
5118 tree
new = test_for_singularity (cond_code
, op0
, op1
, vr
);
5124 fprintf (dump_file
, "Simplified relational ");
5125 print_generic_expr (dump_file
, cond
, 0);
5126 fprintf (dump_file
, " into ");
5129 COND_EXPR_COND (stmt
)
5130 = build2 (EQ_EXPR
, boolean_type_node
, op0
, new);
5135 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
5136 fprintf (dump_file
, "\n");
5142 /* Try again after inverting the condition. We only deal
5143 with integral types here, so no need to worry about
5144 issues with inverting FP comparisons. */
5145 cond_code
= invert_tree_comparison (cond_code
, false);
5146 new = test_for_singularity (cond_code
, op0
, op1
, vr
);
5152 fprintf (dump_file
, "Simplified relational ");
5153 print_generic_expr (dump_file
, cond
, 0);
5154 fprintf (dump_file
, " into ");
5157 COND_EXPR_COND (stmt
)
5158 = build2 (NE_EXPR
, boolean_type_node
, op0
, new);
5163 print_generic_expr (dump_file
, COND_EXPR_COND (stmt
), 0);
5164 fprintf (dump_file
, "\n");
5173 /* Simplify STMT using ranges if possible. */
5176 simplify_stmt_using_ranges (tree stmt
)
5178 if (TREE_CODE (stmt
) == MODIFY_EXPR
)
5180 tree rhs
= TREE_OPERAND (stmt
, 1);
5181 enum tree_code rhs_code
= TREE_CODE (rhs
);
5183 /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR
5184 and BIT_AND_EXPR respectively if the first operand is greater
5185 than zero and the second operand is an exact power of two. */
5186 if ((rhs_code
== TRUNC_DIV_EXPR
|| rhs_code
== TRUNC_MOD_EXPR
)
5187 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0)))
5188 && integer_pow2p (TREE_OPERAND (rhs
, 1)))
5189 simplify_div_or_mod_using_ranges (stmt
, rhs
, rhs_code
);
5191 /* Transform ABS (X) into X or -X as appropriate. */
5192 if (rhs_code
== ABS_EXPR
5193 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == SSA_NAME
5194 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs
, 0))))
5195 simplify_abs_using_ranges (stmt
, rhs
);
5197 else if (TREE_CODE (stmt
) == COND_EXPR
5198 && COMPARISON_CLASS_P (COND_EXPR_COND (stmt
)))
5200 simplify_cond_using_ranges (stmt
);
5204 /* Stack of dest,src equivalency pairs that need to be restored after
5205 each attempt to thread a block's incoming edge to an outgoing edge.
5207 A NULL entry is used to mark the end of pairs which need to be
5209 static VEC(tree
,heap
) *stack
;
5211 /* A trivial wrapper so that we can present the generic jump threading
5212 code with a simple API for simplifying statements. STMT is the
5213 statement we want to simplify, WITHIN_STMT provides the location
5214 for any overflow warnings. */
5217 simplify_stmt_for_jump_threading (tree stmt
, tree within_stmt
)
5219 /* We only use VRP information to simplify conditionals. This is
5220 overly conservative, but it's unclear if doing more would be
5221 worth the compile time cost. */
5222 if (TREE_CODE (stmt
) != COND_EXPR
)
5225 return vrp_evaluate_conditional (COND_EXPR_COND (stmt
), within_stmt
);
5228 /* Blocks which have more than one predecessor and more than
5229 one successor present jump threading opportunities. ie,
5230 when the block is reached from a specific predecessor, we
5231 may be able to determine which of the outgoing edges will
5232 be traversed. When this optimization applies, we are able
5233 to avoid conditionals at runtime and we may expose secondary
5234 optimization opportunities.
5236 This routine is effectively a driver for the generic jump
5237 threading code. It basically just presents the generic code
5238 with edges that may be suitable for jump threading.
5240 Unlike DOM, we do not iterate VRP if jump threading was successful.
5241 While iterating may expose new opportunities for VRP, it is expected
5242 those opportunities would be very limited and the compile time cost
5243 to expose those opportunities would be significant.
5245 As jump threading opportunities are discovered, they are registered
5246 for later realization. */
5249 identify_jump_threads (void)
5254 /* Ugh. When substituting values earlier in this pass we can
5255 wipe the dominance information. So rebuild the dominator
5256 information as we need it within the jump threading code. */
5257 calculate_dominance_info (CDI_DOMINATORS
);
5259 /* We do not allow VRP information to be used for jump threading
5260 across a back edge in the CFG. Otherwise it becomes too
5261 difficult to avoid eliminating loop exit tests. Of course
5262 EDGE_DFS_BACK is not accurate at this time so we have to
5264 mark_dfs_back_edges ();
5266 /* Allocate our unwinder stack to unwind any temporary equivalences
5267 that might be recorded. */
5268 stack
= VEC_alloc (tree
, heap
, 20);
5270 /* To avoid lots of silly node creation, we create a single
5271 conditional and just modify it in-place when attempting to
5273 dummy
= build2 (EQ_EXPR
, boolean_type_node
, NULL
, NULL
);
5274 dummy
= build3 (COND_EXPR
, void_type_node
, dummy
, NULL
, NULL
);
5276 /* Walk through all the blocks finding those which present a
5277 potential jump threading opportunity. We could set this up
5278 as a dominator walker and record data during the walk, but
5279 I doubt it's worth the effort for the classes of jump
5280 threading opportunities we are trying to identify at this
5281 point in compilation. */
5286 /* If the generic jump threading code does not find this block
5287 interesting, then there is nothing to do. */
5288 if (! potentially_threadable_block (bb
))
5291 /* We only care about blocks ending in a COND_EXPR. While there
5292 may be some value in handling SWITCH_EXPR here, I doubt it's
5293 terribly important. */
5294 last
= bsi_stmt (bsi_last (bb
));
5295 if (TREE_CODE (last
) != COND_EXPR
)
5298 /* We're basically looking for any kind of conditional with
5299 integral type arguments. */
5300 cond
= COND_EXPR_COND (last
);
5301 if ((TREE_CODE (cond
) == SSA_NAME
5302 && INTEGRAL_TYPE_P (TREE_TYPE (cond
)))
5303 || (COMPARISON_CLASS_P (cond
)
5304 && TREE_CODE (TREE_OPERAND (cond
, 0)) == SSA_NAME
5305 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond
, 0)))
5306 && (TREE_CODE (TREE_OPERAND (cond
, 1)) == SSA_NAME
5307 || is_gimple_min_invariant (TREE_OPERAND (cond
, 1)))
5308 && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond
, 1)))))
5313 /* We've got a block with multiple predecessors and multiple
5314 successors which also ends in a suitable conditional. For
5315 each predecessor, see if we can thread it to a specific
5317 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
5319 /* Do not thread across back edges or abnormal edges
5321 if (e
->flags
& (EDGE_DFS_BACK
| EDGE_COMPLEX
))
5324 thread_across_edge (dummy
, e
, true,
5326 simplify_stmt_for_jump_threading
);
5331 /* We do not actually update the CFG or SSA graphs at this point as
5332 ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
5333 handle ASSERT_EXPRs gracefully. */
5336 /* We identified all the jump threading opportunities earlier, but could
5337 not transform the CFG at that time. This routine transforms the
5338 CFG and arranges for the dominator tree to be rebuilt if necessary.
5340 Note the SSA graph update will occur during the normal TODO
5341 processing by the pass manager. */
5343 finalize_jump_threads (void)
5345 bool cfg_altered
= false;
5346 cfg_altered
= thread_through_all_blocks ();
5348 /* If we threaded jumps, then we need to recompute the dominance
5349 information, to safely do that we must clean up the CFG first. */
5352 free_dominance_info (CDI_DOMINATORS
);
5353 cleanup_tree_cfg ();
5354 calculate_dominance_info (CDI_DOMINATORS
);
5356 VEC_free (tree
, heap
, stack
);
5360 /* Traverse all the blocks folding conditionals with known ranges. */
5366 prop_value_t
*single_val_range
;
5367 bool do_value_subst_p
;
5371 fprintf (dump_file
, "\nValue ranges after VRP:\n\n");
5372 dump_all_value_ranges (dump_file
);
5373 fprintf (dump_file
, "\n");
5376 /* We may have ended with ranges that have exactly one value. Those
5377 values can be substituted as any other copy/const propagated
5378 value using substitute_and_fold. */
5379 single_val_range
= XNEWVEC (prop_value_t
, num_ssa_names
);
5380 memset (single_val_range
, 0, num_ssa_names
* sizeof (*single_val_range
));
5382 do_value_subst_p
= false;
5383 for (i
= 0; i
< num_ssa_names
; i
++)
5385 && vr_value
[i
]->type
== VR_RANGE
5386 && vr_value
[i
]->min
== vr_value
[i
]->max
)
5388 single_val_range
[i
].value
= vr_value
[i
]->min
;
5389 do_value_subst_p
= true;
5392 if (!do_value_subst_p
)
5394 /* We found no single-valued ranges, don't waste time trying to
5395 do single value substitution in substitute_and_fold. */
5396 free (single_val_range
);
5397 single_val_range
= NULL
;
5400 substitute_and_fold (single_val_range
, true);
5402 /* We must identify jump threading opportunities before we release
5403 the datastructures built by VRP. */
5404 identify_jump_threads ();
5406 /* Free allocated memory. */
5407 for (i
= 0; i
< num_ssa_names
; i
++)
5410 BITMAP_FREE (vr_value
[i
]->equiv
);
5414 free (single_val_range
);
5417 /* So that we can distinguish between VRP data being available
5418 and not available. */
5423 /* Main entry point to VRP (Value Range Propagation). This pass is
5424 loosely based on J. R. C. Patterson, ``Accurate Static Branch
5425 Prediction by Value Range Propagation,'' in SIGPLAN Conference on
5426 Programming Language Design and Implementation, pp. 67-78, 1995.
5427 Also available at http://citeseer.ist.psu.edu/patterson95accurate.html
5429 This is essentially an SSA-CCP pass modified to deal with ranges
5430 instead of constants.
5432 While propagating ranges, we may find that two or more SSA name
5433 have equivalent, though distinct ranges. For instance,
5436 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0>
5438 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
5442 In the code above, pointer p_5 has range [q_2, q_2], but from the
5443 code we can also determine that p_5 cannot be NULL and, if q_2 had
5444 a non-varying range, p_5's range should also be compatible with it.
5446 These equivalences are created by two expressions: ASSERT_EXPR and
5447 copy operations. Since p_5 is an assertion on p_4, and p_4 was the
5448 result of another assertion, then we can use the fact that p_5 and
5449 p_4 are equivalent when evaluating p_5's range.
5451 Together with value ranges, we also propagate these equivalences
5452 between names so that we can take advantage of information from
5453 multiple ranges when doing final replacement. Note that this
5454 equivalency relation is transitive but not symmetric.
5456 In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
5457 cannot assert that q_2 is equivalent to p_5 because q_2 may be used
5458 in contexts where that assertion does not hold (e.g., in line 6).
5460 TODO, the main difference between this pass and Patterson's is that
5461 we do not propagate edge probabilities. We only compute whether
5462 edges can be taken or not. That is, instead of having a spectrum
5463 of jump probabilities between 0 and 1, we only deal with 0, 1 and
5464 DON'T KNOW. In the future, it may be worthwhile to propagate
5465 probabilities to aid branch prediction. */
5470 insert_range_assertions ();
5472 current_loops
= loop_optimizer_init (LOOPS_NORMAL
);
5474 scev_initialize (current_loops
);
5477 ssa_propagate (vrp_visit_stmt
, vrp_visit_phi_node
);
5483 loop_optimizer_finalize (current_loops
);
5484 current_loops
= NULL
;
5487 /* ASSERT_EXPRs must be removed before finalizing jump threads
5488 as finalizing jump threads calls the CFG cleanup code which
5489 does not properly handle ASSERT_EXPRs. */
5490 remove_range_assertions ();
5492 /* If we exposed any new variables, go ahead and put them into
5493 SSA form now, before we handle jump threading. This simplifies
5494 interactions between rewriting of _DECL nodes into SSA form
5495 and rewriting SSA_NAME nodes into SSA form after block
5496 duplication and CFG manipulation. */
5497 update_ssa (TODO_update_ssa
);
5499 finalize_jump_threads ();
5506 return flag_tree_vrp
!= 0;
5509 struct tree_opt_pass pass_vrp
=
5512 gate_vrp
, /* gate */
5513 execute_vrp
, /* execute */
5516 0, /* static_pass_number */
5517 TV_TREE_VRP
, /* tv_id */
5518 PROP_ssa
| PROP_alias
, /* properties_required */
5519 0, /* properties_provided */
5520 PROP_smt_usage
, /* properties_destroyed */
5521 0, /* todo_flags_start */
5527 | TODO_update_smt_usage
, /* todo_flags_finish */