[PATCH] x86_64: Add atanh with FMA

[Sunil Pandey]

On Mon, Mar 17, 2025 at 8:48 AM Sunil Pandey <skpgkp2@gmail.com> wrote:

>
>
> On Thu, Mar 13, 2025 at 1:24 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
>> On Thu, Mar 13, 2025 at 1:07 PM Sunil K Pandey <skpgkp2@gmail.com> wrote:
>> >
>> > On SPR, it improves atanh bench performance by:
>> >
>> >                         Before          After           Improvement
>> > reciprocal-throughput   15.1715         14.8628         2%
>> > latency                 57.1941         56.1883         2%
>> > ---
>> >  benchtests/atanh-inputs                    |  1 +
>> >  sysdeps/ieee754/dbl-64/e_atanh.c           |  8 +++++
>> >  sysdeps/x86_64/fpu/multiarch/Makefile      |  2 ++
>> >  sysdeps/x86_64/fpu/multiarch/e_atanh-fma.c |  6 ++++
>> >  sysdeps/x86_64/fpu/multiarch/e_atanh.c     | 34 ++++++++++++++++++++++
>> >  5 files changed, 51 insertions(+)
>> >  create mode 100644 sysdeps/x86_64/fpu/multiarch/e_atanh-fma.c
>> >  create mode 100644 sysdeps/x86_64/fpu/multiarch/e_atanh.c
>> >
>> > diff --git a/benchtests/atanh-inputs b/benchtests/atanh-inputs
>> > index 455aa65b65..4985293254 100644
>> > --- a/benchtests/atanh-inputs
>> > +++ b/benchtests/atanh-inputs
>> > @@ -1,6 +1,7 @@
>> >  ## args: double
>> >  ## ret: double
>> >  ## includes: math.h
>> > +## name: workload-random
>> >  0x1.5a2730bacd94ap-1
>> >  -0x1.b57eb40fc048ep-21
>> >  -0x1.c0b185fb450e2p-17
>> > diff --git a/sysdeps/ieee754/dbl-64/e_atanh.c
>> b/sysdeps/ieee754/dbl-64/e_atanh.c
>> > index 1e09e46f0f..d1c71b2aa4 100644
>> > --- a/sysdeps/ieee754/dbl-64/e_atanh.c
>> > +++ b/sysdeps/ieee754/dbl-64/e_atanh.c
>> > @@ -44,6 +44,11 @@
>> >
>> >  static const double huge = 1e300;
>> >
>> > +#ifndef SECTION
>> > +# define SECTION
>> > +#endif
>> > +
>> > +SECTION
>> >  double
>> >  __ieee754_atanh (double x)
>> >  {
>> > @@ -73,4 +78,7 @@ __ieee754_atanh (double x)
>> >
>> >    return copysign (t, x);
>> >  }
>> > +
>> > +#ifndef __ieee754_atanh
>> >  libm_alias_finite (__ieee754_atanh, __atanh)
>> > +#endif
>> > diff --git a/sysdeps/x86_64/fpu/multiarch/Makefile
>> b/sysdeps/x86_64/fpu/multiarch/Makefile
>> > index 61ff78efa3..3403422443 100644
>> > --- a/sysdeps/x86_64/fpu/multiarch/Makefile
>> > +++ b/sysdeps/x86_64/fpu/multiarch/Makefile
>> > @@ -1,6 +1,7 @@
>> >  ifeq ($(subdir),math)
>> >  CFLAGS-e_asin-fma.c = -mfma -mavx2
>> >  CFLAGS-e_atan2-fma.c = -mfma -mavx2
>> > +CFLAGS-e_atanh-fma.c = -mfma -mavx2
>> >  CFLAGS-e_exp-fma.c = -mfma -mavx2
>> >  CFLAGS-e_log-fma.c = -mfma -mavx2
>> >  CFLAGS-e_log2-fma.c = -mfma -mavx2
>> > @@ -59,6 +60,7 @@ libm-sysdep_routines += \
>> >    e_asin-fma \
>> >    e_atan2-avx \
>> >    e_atan2-fma \
>> > +  e_atanh-fma \
>> >    e_exp-avx \
>> >    e_exp-fma \
>> >    e_exp2f-fma \
>> > diff --git a/sysdeps/x86_64/fpu/multiarch/e_atanh-fma.c
>> b/sysdeps/x86_64/fpu/multiarch/e_atanh-fma.c
>> > new file mode 100644
>> > index 0000000000..c3f2f9e550
>> > --- /dev/null
>> > +++ b/sysdeps/x86_64/fpu/multiarch/e_atanh-fma.c
>> > @@ -0,0 +1,6 @@
>> > +#define __ieee754_atanh __ieee754_atanh_fma
>> > +#define __log1p __log1p_fma
>> > +
>> > +#define SECTION __attribute__ ((section (".text.fma")))
>> > +
>> > +#include <sysdeps/ieee754/dbl-64/e_atanh.c>
>> > diff --git a/sysdeps/x86_64/fpu/multiarch/e_atanh.c
>> b/sysdeps/x86_64/fpu/multiarch/e_atanh.c
>> > new file mode 100644
>> > index 0000000000..d2b785dfc0
>> > --- /dev/null
>> > +++ b/sysdeps/x86_64/fpu/multiarch/e_atanh.c
>> > @@ -0,0 +1,34 @@
>> > +/* Multiple versions of atanh.
>> > +   Copyright (C) 2025 Free Software Foundation, Inc.
>> > +   This file is part of the GNU C Library.
>> > +
>> > +   The GNU C Library is free software; you can redistribute it and/or
>> > +   modify it under the terms of the GNU Lesser General Public
>> > +   License as published by the Free Software Foundation; either
>> > +   version 2.1 of the License, or (at your option) any later version.
>> > +
>> > +   The GNU C Library is distributed in the hope that it will be useful,
>> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
>> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> > +   Lesser General Public License for more details.
>> > +
>> > +   You should have received a copy of the GNU Lesser General Public
>> > +   License along with the GNU C Library; if not, see
>> > +   <https://www.gnu.org/licenses/>.  */
>> > +
>> > +#include <sysdeps/x86/isa-level.h>
>> > +#if MINIMUM_X86_ISA_LEVEL < AVX2_X86_ISA_LEVEL
>> > +# include <libm-alias-finite.h>
>> > +
>> > +extern double __redirect_ieee754_atanh (double);
>> > +
>> > +# define SYMBOL_NAME ieee754_atanh
>> > +# include "ifunc-fma.h"
>> > +
>> > +libc_ifunc_redirected (__redirect_ieee754_atanh, __ieee754_atanh,
>> IFUNC_SELECTOR ());
>> > +
>> > +libm_alias_finite (__ieee754_atanh, __atanh)
>> > +
>> > +# define __ieee754_atanh __ieee754_atanh_sse2
>> > +#endif
>> > +#include <sysdeps/ieee754/dbl-64/e_atanh.c>
>> > --
>> > 2.48.1
>> >
>>
>> LGTM.
>>
>> Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
>>
>> Thanks.
>>
>> --
>> H.J.
>>
>
>
>

I would like to backport this patch to release branches.
Any comments or objections?

--Sunil
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