(this message looks like it was lost in my draft folder...)
On Tue, 26 May 2015, Richard Biener wrote:
+(match zerop integer_zerop)
+(match zerop real_zerop)
Would it also include fixed_zerop?
Probably, yes. The main issue is that I know next to nothing about
fixed-point types, so I am always unsure how to handle them (when I don't
forget them completely). For instance, in the recently added -A CMP -B, we
could probably replace
(if (FLOAT_TYPE_P (TREE_TYPE (@0))
|| (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
&& TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0))))
with
(if (FLOAT_TYPE_P (TREE_TYPE (@0))
|| TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)))
Note that with inlining implemented it would duplicate the pattern for
each match variant thus in this case adding a tree.[ch] function zerop
() might be better.
Ah... I actually thought we might end up moving things like integer_zerop
from tree.c to match.pd, especially since predicates are not declared
'static'... Ok, reverse gear.
Note that inlining does not seem necessary to implement more advanced
predicates like negated_value_for_comparison in the parent message.
+ (simplify
+ (cnd (cmp @0 zerop) (convert?@2 @0) (negate@1 @2))
+ (if (cmp == EQ_EXPR || cmp == UNEQ_EXPR)
+ @1)
+ (if (cmp == NE_EXPR || cmp == LTGT_EXPR)
+ (non_lvalue @2))
+ (if (TYPE_SIGN (TREE_TYPE (@0)) == SIGNED /* implicit */
+ && TYPE_SIGN (type) == SIGNED
+ && element_precision (type) >= element_precision (TREE_TYPE (@0)))
+ (if (cmp == GE_EXPR || cmp == GT_EXPR
+ || (!flag_trapping_math && (cmp == UNGE_EXPR || cmp == UNGT_EXPR)))
+ (abs @2))
+ (if (cmp == LE_EXPR || cmp == LT_EXPR
+ || (!flag_trapping_math && (cmp == UNLE_EXPR || cmp == UNLT_EXPR)))
+ (negate (abs @2)))))
+ /* Now with the branches swapped. */
+ (simplify
+ (cnd (cmp @0 zerop) (negate@1 (convert?@2 @0)) @2)
not obvious from a quick look - but would you be able to remove the
swapped branch
vairant if (cnd:c (cmp @0 zerop) X Y) would work by swapping X and Y?
Hmm. How do I test if I am currently in the original or commuted version
of the simplification? I could add a "with" block that defines truecmp as
either cmp or invert_tree_comparison (cmp) and test that. Otherwise, I
would need a test before each "return" as swapped versions don't return
the same thing. It might make a slight difference on the handling of
flag_trapping_math, but that handling already seems strange to me...
The fold-const.c code doesn't seem to handle as many variants (esp.
the swapping?),
The fold-const.c function is called twice, once on regular operands, once
with inverted comparison and swapped operands. I really don't think I am
handling more cases (except maybe the silly a?a:0 is extended to
unsigned).
so maybe you can add a testcase that exercises some of the above on GIMPLE?
So mostly the VEC_COND_EXPR version? We don't seem to have that much
COND_EXPR left in gimple.
--
Marc Glisse
