Re: [PATCH v8 3/4] x86_64: roundeven with sse4.1 support

[Sunil Pandey <skpgkp2@gmail.com>]

On Wed, Jun 23, 2021 at 3:32 PM H.J. Lu via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> From: Shen-Ta Hsieh <ibmibmibm.tw@gmail.com>
>
> This patch adds support for the sse4.1 hardware floating point
> roundeven.
>
> Here is some benchmark results on my systems:
>
> =AMD Ryzen 9 3900X 12-Core Processor=
>
> * benchmark result before this commit
> |            |    roundeven |   roundevenf |
> |------------|--------------|--------------|
> | duration   |  3.75587e+09 |  3.75114e+09 |
> | iterations |  3.93053e+08 |  4.35402e+08 |
> | max        | 52.592       | 58.71        |
> | min        |  7.98        |  7.22        |
> | mean       |  9.55563     |  8.61535     |
>
> * benchmark result after this commit
> |            |     roundeven |   roundevenf |
> |------------|---------------|--------------|
> | duration   |   3.73815e+09 |  3.73738e+09 |
> | iterations |   5.82692e+08 |  5.91498e+08 |
> | max        |  56.468       | 51.642       |
> | min        |   6.27        |  6.156       |
> | mean       |   6.41532     |  6.3185      |
>
> =Intel(R) Pentium(R) CPU D1508 @ 2.20GHz=
>
> * benchmark result before this commit
> |            |    roundeven |   roundevenf |
> |------------|--------------|--------------|
> | duration   |  2.18208e+09 |  2.18258e+09 |
> | iterations |  2.39932e+08 |  2.46924e+08 |
> | max        | 96.378       | 98.035       |
> | min        |  6.776       |  5.94        |
> | mean       |  9.09456     |  8.83907     |
>
> * benchmark result after this commit
> |            |    roundeven |   roundevenf |
> |------------|--------------|--------------|
> | duration   |  2.17415e+09 |  2.17005e+09 |
> | iterations |  3.56193e+08 |  4.09824e+08 |
> | max        | 51.693       | 97.192       |
> | min        |  5.926       |  5.093       |
> | mean       |  6.10385     |  5.29507     |
>
> Signed-off-by: Shen-Ta Hsieh <ibmibmibm.tw@gmail.com>
> Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
> ---
>  sysdeps/x86_64/fpu/multiarch/Makefile         |  5 +--
>  sysdeps/x86_64/fpu/multiarch/s_roundeven-c.c  |  2 ++
>  .../x86_64/fpu/multiarch/s_roundeven-sse4_1.S | 24 ++++++++++++++
>  sysdeps/x86_64/fpu/multiarch/s_roundeven.c    | 31 +++++++++++++++++++
>  sysdeps/x86_64/fpu/multiarch/s_roundevenf-c.c |  3 ++
>  .../fpu/multiarch/s_roundevenf-sse4_1.S       | 24 ++++++++++++++
>  sysdeps/x86_64/fpu/multiarch/s_roundevenf.c   | 31 +++++++++++++++++++
>  7 files changed, 118 insertions(+), 2 deletions(-)
>  create mode 100644 sysdeps/x86_64/fpu/multiarch/s_roundeven-c.c
>  create mode 100644 sysdeps/x86_64/fpu/multiarch/s_roundeven-sse4_1.S
>  create mode 100644 sysdeps/x86_64/fpu/multiarch/s_roundeven.c
>  create mode 100644 sysdeps/x86_64/fpu/multiarch/s_roundevenf-c.c
>  create mode 100644 sysdeps/x86_64/fpu/multiarch/s_roundevenf-sse4_1.S
>  create mode 100644 sysdeps/x86_64/fpu/multiarch/s_roundevenf.c
>
> diff --git a/sysdeps/x86_64/fpu/multiarch/Makefile b/sysdeps/x86_64/fpu/multiarch/Makefile
> index 57892c56bb..d425ffd6d3 100644
> --- a/sysdeps/x86_64/fpu/multiarch/Makefile
> +++ b/sysdeps/x86_64/fpu/multiarch/Makefile
> @@ -1,11 +1,12 @@
>  ifeq ($(subdir),math)
>  libm-sysdep_routines += s_floor-c s_ceil-c s_floorf-c s_ceilf-c \
>                         s_rint-c s_rintf-c s_nearbyint-c s_nearbyintf-c \
> -                       s_trunc-c s_truncf-c
> +                       s_roundeven-c s_roundevenf-c s_trunc-c s_truncf-c
>
>  libm-sysdep_routines += s_ceil-sse4_1 s_ceilf-sse4_1 s_floor-sse4_1 \
>                         s_floorf-sse4_1 s_nearbyint-sse4_1 \
> -                       s_nearbyintf-sse4_1 s_rint-sse4_1 s_rintf-sse4_1 \
> +                       s_nearbyintf-sse4_1 s_roundeven-sse4_1 \
> +                       s_roundevenf-sse4_1 s_rint-sse4_1 s_rintf-sse4_1 \
>                         s_trunc-sse4_1 s_truncf-sse4_1
>
>  libm-sysdep_routines += e_exp-fma e_log-fma e_pow-fma s_atan-fma \
> diff --git a/sysdeps/x86_64/fpu/multiarch/s_roundeven-c.c b/sysdeps/x86_64/fpu/multiarch/s_roundeven-c.c
> new file mode 100644
> index 0000000000..c7be43cb22
> --- /dev/null
> +++ b/sysdeps/x86_64/fpu/multiarch/s_roundeven-c.c
> @@ -0,0 +1,2 @@
> +#define __roundeven __roundeven_c
> +#include <sysdeps/ieee754/dbl-64/s_roundeven.c>
> diff --git a/sysdeps/x86_64/fpu/multiarch/s_roundeven-sse4_1.S b/sysdeps/x86_64/fpu/multiarch/s_roundeven-sse4_1.S
> new file mode 100644
> index 0000000000..6ae8f6b1d3
> --- /dev/null
> +++ b/sysdeps/x86_64/fpu/multiarch/s_roundeven-sse4_1.S
> @@ -0,0 +1,24 @@
> +/* Copyright (C) 2021 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 <sysdep.h>
> +
> +       .section .text.sse4.1,"ax",@progbits
> +ENTRY(__roundeven_sse41)
> +       roundsd $8, %xmm0, %xmm0
> +       ret
> +END(__roundeven_sse41)
> diff --git a/sysdeps/x86_64/fpu/multiarch/s_roundeven.c b/sysdeps/x86_64/fpu/multiarch/s_roundeven.c
> new file mode 100644
> index 0000000000..d92eda652a
> --- /dev/null
> +++ b/sysdeps/x86_64/fpu/multiarch/s_roundeven.c
> @@ -0,0 +1,31 @@
> +/* Multiple versions of __roundeven.
> +   Copyright (C) 2021 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 <libm-alias-double.h>
> +
> +#define roundeven __redirect_roundeven
> +#define __roundeven __redirect___roundeven
> +#include <math.h>
> +#undef roundeven
> +#undef __roundeven
> +
> +#define SYMBOL_NAME roundeven
> +#include "ifunc-sse4_1.h"
> +
> +libc_ifunc_redirected (__redirect_roundeven, __roundeven, IFUNC_SELECTOR ());
> +libm_alias_double (__roundeven, roundeven)
> diff --git a/sysdeps/x86_64/fpu/multiarch/s_roundevenf-c.c b/sysdeps/x86_64/fpu/multiarch/s_roundevenf-c.c
> new file mode 100644
> index 0000000000..72a6e7d1fb
> --- /dev/null
> +++ b/sysdeps/x86_64/fpu/multiarch/s_roundevenf-c.c
> @@ -0,0 +1,3 @@
> +#undef __roundevenf
> +#define __roundevenf __roundevenf_c
> +#include <sysdeps/ieee754/flt-32/s_roundevenf.c>
> diff --git a/sysdeps/x86_64/fpu/multiarch/s_roundevenf-sse4_1.S b/sysdeps/x86_64/fpu/multiarch/s_roundevenf-sse4_1.S
> new file mode 100644
> index 0000000000..a76e10807e
> --- /dev/null
> +++ b/sysdeps/x86_64/fpu/multiarch/s_roundevenf-sse4_1.S
> @@ -0,0 +1,24 @@
> +/* Copyright (C) 2021 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 <sysdep.h>
> +
> +       .section .text.sse4.1,"ax",@progbits
> +ENTRY(__roundevenf_sse41)
> +       roundss $8, %xmm0, %xmm0
> +       ret
> +END(__roundevenf_sse41)
> diff --git a/sysdeps/x86_64/fpu/multiarch/s_roundevenf.c b/sysdeps/x86_64/fpu/multiarch/s_roundevenf.c
> new file mode 100644
> index 0000000000..2ee196e68f
> --- /dev/null
> +++ b/sysdeps/x86_64/fpu/multiarch/s_roundevenf.c
> @@ -0,0 +1,31 @@
> +/* Multiple versions of __roundevenf.
> +   Copyright (C) 2021 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 <libm-alias-float.h>
> +
> +#define roundevenf __redirect_roundevenf
> +#define __roundevenf __redirect___roundevenf
> +#include <math.h>
> +#undef roundevenf
> +#undef __roundevenf
> +
> +#define SYMBOL_NAME roundevenf
> +#include "ifunc-sse4_1.h"
> +
> +libc_ifunc_redirected (__redirect_roundevenf, __roundevenf, IFUNC_SELECTOR ());
> +libm_alias_float (__roundeven, roundeven)
> --
> 2.31.1
>

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

--Sunil