[PATCH] x86_64: Add atanh with FMA

[H.J. Lu]

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.