Re: [PATCH] Fold (a > 0 ? 1.0 : -1.0) into copysign (1.0, a) and a * copysign (1.0, a) into abs(a)

[Jakub Jelinek]

On Tue, Jun 27, 2017 at 10:52:47AM -0700, Andrew Pinski wrote:
> On Tue, Jun 27, 2017 at 7:56 AM, Richard Biener
> <richard.guent...@gmail.com> wrote:
> > On June 27, 2017 4:52:28 PM GMT+02:00, Tamar Christina 
> > <tamar.christ...@arm.com> wrote:
> >>> >> +(for cmp (gt ge lt le)
> >>> >> +     outp (convert convert negate negate)
> >>> >> +     outn (negate negate convert convert)
> >>> >> + /* Transform (X > 0.0 ? 1.0 : -1.0) into copysign(1, X). */
> >>> >> + /* Transform (X >= 0.0 ? 1.0 : -1.0) into copysign(1, X). */
> >>> >> + /* Transform (X < 0.0 ? 1.0 : -1.0) into copysign(1,-X). */
> >>> >> + /* Transform (X <= 0.0 ? 1.0 : -1.0) into copysign(1,-X). */
> >>> >> +(simplify
> >>> >> +  (cond (cmp @0 real_zerop) real_onep real_minus_onep)
> >>> >> +  (if (!HONOR_NANS (type) && !HONOR_SIGNED_ZEROS (type)
> >>> >> +       && types_match (type, TREE_TYPE (@0)))
> >>> >> +   (switch
> >>> >> +    (if (types_match (type, float_type_node))
> >>> >> +     (BUILT_IN_COPYSIGNF { build_one_cst (type); } (outp @0)))
> >>> >> +    (if (types_match (type, double_type_node))
> >>> >> +     (BUILT_IN_COPYSIGN { build_one_cst (type); } (outp @0)))
> >>> >> +    (if (types_match (type, long_double_type_node))
> >>> >> +     (BUILT_IN_COPYSIGNL { build_one_cst (type); } (outp @0))))))

The patch regressed the gcc.target/i386/cmov7.c testcase.
>From the description in the testcase it was testing the combiner, so I've
transformed it into something that also tests the combiner the same way,
ok for trunk?  That said, for copysign if we match it we don't emit a fcmov
while it might be a good idea.

2017-06-28  Jakub Jelinek  <ja...@redhat.com>

        * gcc.target/i386/cmov7.c (sgn): Renamed to ...
        (foo): ... this.  Change constants such that it isn't matched
        as __builtin_copysign, yet tests the combiner the same.

--- gcc/testsuite/gcc.target/i386/cmov7.c.jj    2016-05-22 12:20:23.000000000 
+0200
+++ gcc/testsuite/gcc.target/i386/cmov7.c       2017-06-28 09:20:24.000000000 
+0200
@@ -10,7 +10,7 @@
    (set (reg:DF) (float_extend:DF (mem:SF (symbol_ref...)))).  */
 
 double
-sgn (double __x)
+foo (double __x)
 {
-  return __x >= 0.0 ? 1.0 : -1.0;
+  return __x >= 1.0 ? 0.0 : -1.0;
 }


        Jakub