On Sun, Jun 28, 2015 at 8:34 PM, Marc Glisse <marc.gli...@inria.fr> wrote: > (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)))
Not sure if TYPE_OVERFLOW_UNDEFINED says sth sensible for fixed-point types given that there is no overflow for them but they saturate. As far as I see the check would even ICE without guarding it with ANY_INTEGRAL_TYPE_P. So it would be || NON_SAT_FIXED_POINT_TYPE_P (TREE_TYPE (@0)) where I am not sure whether overflow is undefined for non-saturating fixed-point types ... > >> 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. Yeah, I don't think match.pd is a good fit for them. > Note that inlining does not seem necessary to implement more advanced > predicates like negated_value_for_comparison in the parent message. Sure not necessary but one point of match-and-simplify was that the pattern matching is fast because it uses a decision tree. Once you introduce predicates that are in functions with their own decision tree you get back to testing all of them. >> + (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? You can't. > 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... (cnd:c (cmp @0 zerop) (convert?@2 @0) (negate@1 @2)) would get you (cnd (cmp @0 zerop) (convert?@2 @0) (negate@1 @2)) and (cnd (cmp @0 zerop) (negate@1 @2) (convert?@2 @0)) in the patterns it almost literally looked like what you did manually. >> 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). Ok. >> 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. Ah, true. Yes, the vector variant then. Thanks, Richard. > -- > Marc Glisse
