Yuri Gribov <tetra2...@gmail.com> writes: > Hi all, > > This is a second iteration of patch which gets rid of float casts in > comparisons when all values of casted integral type are exactly > representable by the float type > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81376). The new version > addresses Richard's review > (https://gcc.gnu.org/ml/gcc-patches/2017-10/msg00481.html). > > Bootstrapped and regtested on x64_64. Ok to commit? > > -Y > > From 1ea62f7bf4394142e0c473a69de8a0e9b1718a69 Mon Sep 17 00:00:00 2001 > From: Yury Gribov <tetra2...@gmail.com> > Date: Fri, 29 Sep 2017 07:34:54 +0200 > Subject: [PATCH] Add pattern to remove useless float casts in comparison. > > 2018-02-17 Yury Gribov <tetra2...@gmail.com> > > PR middle-end/81376 > > gcc/ > * real.c (format_helper::can_represent_integral_type_p): New function > * real.h (format_helper::can_represent_integral_type_p): Ditto. > * match.pd: New pattern. > > gcc/testsuite/ > * c-c++-common/pr81376.c: New test. > --- > gcc/match.pd | 30 ++++++++++++++++++++------- > gcc/real.c | 13 ++++++++++++ > gcc/real.h | 1 + > gcc/testsuite/c-c++-common/pr81376.c | 39 > ++++++++++++++++++++++++++++++++++++ > 4 files changed, 76 insertions(+), 7 deletions(-) > create mode 100644 gcc/testsuite/c-c++-common/pr81376.c > > diff --git a/gcc/match.pd b/gcc/match.pd > index 4452b58..33a5f36 100644 > --- a/gcc/match.pd > +++ b/gcc/match.pd > @@ -3252,6 +3252,27 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) > (if (! HONOR_NANS (@0)) > (cmp @0 @1)))))) > > +/* Optimize various special cases of (FTYPE) N CMP (FTYPE) M. */ > +(for cmp (tcc_comparison) > + (simplify > + (cmp (float@0 @1) (float @2)) > + (if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (@0)) > + && ! DECIMAL_FLOAT_TYPE_P (TREE_TYPE (@0))) > + (with > + { > + format_helper fmt (REAL_MODE_FORMAT (TYPE_MODE (TREE_TYPE (@0)))); > + tree type1 = TREE_TYPE (@1); > + tree type2 = TREE_TYPE (@2); > + } > + (if (fmt.can_represent_integral_type_p (type1) > + && fmt.can_represent_integral_type_p (type2)) > + (if (TYPE_PRECISION (type1) > TYPE_PRECISION (type2)) > + (cmp @1 (convert @2)) > + (if (TYPE_PRECISION (type1) < TYPE_PRECISION (type2)) > + (cmp (convert:type2 @1) @2) > + (if (TYPE_SIGN (type1) == TYPE_SIGN (type2)) > + (cmp @1 @2)))))))))
I think this would mishandle combinations in which the wider type is unsigned and the narrower type is signed, like @1:short @2:unsigned int. Thanks, Richard
