[PATCH] x86_64: Add tanh with FMA

[Sunil Pandey]

On Mon, Mar 17, 2025 at 8:49 AM Sunil Pandey <skpgkp2@gmail.com> wrote:

>
>
> On Wed, Mar 12, 2025 at 3:02 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
>> On Wed, Mar 12, 2025 at 2:00 PM Sunil K Pandey <skpgkp2@gmail.com> wrote:
>> >
>> > On Skylake, it improves tanh bench performance by:
>> >
>> >         Before          After           Improvement
>> > max     110.89          95.826          14%
>> > min     20.966          20.157          4%
>> > mean    30.9601         29.8431         4%
>> > ---
>> >  sysdeps/ieee754/dbl-64/s_tanh.c           |  5 ++++
>> >  sysdeps/x86_64/fpu/multiarch/Makefile     |  2 ++
>> >  sysdeps/x86_64/fpu/multiarch/s_tanh-fma.c | 11 ++++++++
>> >  sysdeps/x86_64/fpu/multiarch/s_tanh.c     | 31 +++++++++++++++++++++++
>> >  4 files changed, 49 insertions(+)
>> >  create mode 100644 sysdeps/x86_64/fpu/multiarch/s_tanh-fma.c
>> >  create mode 100644 sysdeps/x86_64/fpu/multiarch/s_tanh.c
>> >
>> > diff --git a/sysdeps/ieee754/dbl-64/s_tanh.c
>> b/sysdeps/ieee754/dbl-64/s_tanh.c
>> > index 673a97102d..13063db04e 100644
>> > --- a/sysdeps/ieee754/dbl-64/s_tanh.c
>> > +++ b/sysdeps/ieee754/dbl-64/s_tanh.c
>> > @@ -46,6 +46,11 @@ static char rcsid[] = "$NetBSD: s_tanh.c,v 1.7
>> 1995/05/10 20:48:22 jtc Exp $";
>> >
>> >  static const double one = 1.0, two = 2.0, tiny = 1.0e-300;
>> >
>> > +#ifndef SECTION
>> > +# define SECTION
>> > +#endif
>> > +
>> > +SECTION
>> >  double
>> >  __tanh (double x)
>> >  {
>> > diff --git a/sysdeps/x86_64/fpu/multiarch/Makefile
>> b/sysdeps/x86_64/fpu/multiarch/Makefile
>> > index e823d2fcc6..a198315f1c 100644
>> > --- a/sysdeps/x86_64/fpu/multiarch/Makefile
>> > +++ b/sysdeps/x86_64/fpu/multiarch/Makefile
>> > @@ -10,6 +10,7 @@ CFLAGS-s_expm1-fma.c = -mfma -mavx2
>> >  CFLAGS-s_log1p-fma.c = -mfma -mavx2
>> >  CFLAGS-s_sin-fma.c = -mfma -mavx2
>> >  CFLAGS-s_tan-fma.c = -mfma -mavx2
>> > +CFLAGS-s_tanh-fma.c = -mfma -mavx2
>> >  CFLAGS-s_sincos-fma.c = -mfma -mavx2
>> >  CFLAGS-s_exp10m1f-fma.c = -mfma -mavx2
>> >  CFLAGS-s_exp2m1f-fma.c = -mfma -mavx2
>> > @@ -96,6 +97,7 @@ libm-sysdep_routines += \
>> >    s_sinf-sse2 \
>> >    s_tan-avx \
>> >    s_tan-fma \
>> > +  s_tanh-fma \
>> >    s_trunc-sse4_1 \
>> >    s_truncf-sse4_1 \
>> >  # libm-sysdep_routines
>> > diff --git a/sysdeps/x86_64/fpu/multiarch/s_tanh-fma.c
>> b/sysdeps/x86_64/fpu/multiarch/s_tanh-fma.c
>> > new file mode 100644
>> > index 0000000000..1b808b1227
>> > --- /dev/null
>> > +++ b/sysdeps/x86_64/fpu/multiarch/s_tanh-fma.c
>> > @@ -0,0 +1,11 @@
>> > +#define __tanh __tanh_fma
>> > +#define __expm1 __expm1_fma
>> > +
>> > +/* NB: __expm1 may be expanded to __expm1_fma in the following
>> > +   prototypes.  */
>> > +extern long double __expm1l (long double);
>> > +extern long double __expm1f128 (long double);
>> > +
>> > +#define SECTION __attribute__ ((section (".text.fma")))
>> > +
>> > +#include <sysdeps/ieee754/dbl-64/s_tanh.c>
>> > diff --git a/sysdeps/x86_64/fpu/multiarch/s_tanh.c
>> b/sysdeps/x86_64/fpu/multiarch/s_tanh.c
>> > new file mode 100644
>> > index 0000000000..5539b6c61c
>> > --- /dev/null
>> > +++ b/sysdeps/x86_64/fpu/multiarch/s_tanh.c
>> > @@ -0,0 +1,31 @@
>> > +/* Multiple versions of tanh.
>> > +   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
>> > +
>> > +extern double __redirect_tanh (double);
>> > +
>> > +# define SYMBOL_NAME tanh
>> > +# include "ifunc-fma.h"
>> > +
>> > +libc_ifunc_redirected (__redirect_tanh, __tanh, IFUNC_SELECTOR ());
>> > +
>> > +# define __tanh __tanh_sse2
>> > +#endif
>> > +#include <sysdeps/ieee754/dbl-64/s_tanh.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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