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Re: [PATCH 09/10] i386: Replace assembly versions of e_log2f with generic e_log2f.c
On Thu, Oct 19, 2017 at 10:31 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> This patch replaces i386 assembly versions of e_log2f with generic
> e_log2f.c. For workload-spec2017.wrf, on Nehalem, it improves
> performance by:
>
> Before After Improvement
> reciprocal-throughput 92.3845 30.8752 199%
> latency 112.855 54.8645 105%
>
> On Skylake, it improves performance by:
>
> Before After Improvement
> reciprocal-throughput 98.7488 22.7507 334%
> latency 118.01 51.6083 128%
On IvyBridge with --disable-multi-arch, it improves performance by:
Before After Improvement
reciprocal-throughput 106.635 28.8596 269%
latency 129.888 56.9187 128%
> * sysdeps/i386/fpu/e_log2f.S: Removed.
> * sysdeps/i386/fpu/e_log2f_data.c: Likewise.
> * sysdeps/i386/fpu/w_log2f.c: Likewise.
> * sysdeps/i386/fpu/libm-test-ulps: Updated for generic e_log2f.c.
> * sysdeps/i386/i686/fpu/multiarch/libm-test-ulps: Likewise.
> * sysdeps/i386/i686/fpu/multiarch/Makefile (libm-sysdep_routines):
> Add e_log2f-sse2.
> (CFLAGS-e_log2f-sse2.c): New.
> * sysdeps/i386/i686/fpu/multiarch/e_log2f-sse2.c: New file.
> * sysdeps/i386/i686/fpu/multiarch/e_log2f.c: Likewise.
> ---
> sysdeps/i386/fpu/e_log2f.S | 69 --------------------------
> sysdeps/i386/fpu/e_log2f_data.c | 1 -
> sysdeps/i386/fpu/libm-test-ulps | 2 +
> sysdeps/i386/fpu/w_log2f.c | 1 -
> sysdeps/i386/i686/fpu/multiarch/Makefile | 3 +-
> sysdeps/i386/i686/fpu/multiarch/e_log2f-sse2.c | 3 ++
> sysdeps/i386/i686/fpu/multiarch/e_log2f.c | 40 +++++++++++++++
> sysdeps/i386/i686/fpu/multiarch/libm-test-ulps | 2 +
> 8 files changed, 49 insertions(+), 72 deletions(-)
> delete mode 100644 sysdeps/i386/fpu/e_log2f.S
> delete mode 100644 sysdeps/i386/fpu/e_log2f_data.c
> delete mode 100644 sysdeps/i386/fpu/w_log2f.c
> create mode 100644 sysdeps/i386/i686/fpu/multiarch/e_log2f-sse2.c
> create mode 100644 sysdeps/i386/i686/fpu/multiarch/e_log2f.c
>
> diff --git a/sysdeps/i386/fpu/e_log2f.S b/sysdeps/i386/fpu/e_log2f.S
> deleted file mode 100644
> index 344eeb495e..0000000000
> --- a/sysdeps/i386/fpu/e_log2f.S
> +++ /dev/null
> @@ -1,69 +0,0 @@
> -/*
> - * Written by J.T. Conklin <jtc@netbsd.org>.
> - * Adapted for use as log2 by Ulrich Drepper <drepper@cygnus.com>.
> - * Public domain.
> - *
> - * Changed to use fyl2xp1 for values near 1, <drepper@cygnus.com>.
> - */
> -
> -#include <machine/asm.h>
> -
> - .section .rodata.cst8,"aM",@progbits,8
> -
> - .p2align 3
> - .type one,@object
> -one: .double 1.0
> - ASM_SIZE_DIRECTIVE(one)
> - /* It is not important that this constant is precise. It is only
> - a value which is known to be on the safe side for using the
> - fyl2xp1 instruction. */
> - .type limit,@object
> -limit: .double 0.29
> - ASM_SIZE_DIRECTIVE(limit)
> -
> -
> -#ifdef PIC
> -# define MO(op) op##@GOTOFF(%edx)
> -#else
> -# define MO(op) op
> -#endif
> -
> - .text
> -ENTRY(__ieee754_log2f)
> -#ifdef PIC
> - LOAD_PIC_REG (dx)
> -#endif
> - fldl MO(one)
> - flds 4(%esp) // x : 1
> - fxam
> - fnstsw
> - fld %st // x : x : 1
> - sahf
> - jc 3f // in case x is NaN or ±Inf
> -4: fsub %st(2), %st // x-1 : x : 1
> - fld %st // x-1 : x-1 : x : 1
> - fabs // |x-1| : x-1 : x : 1
> - fcompl MO(limit) // x-1 : x : 1
> - fnstsw // x-1 : x : 1
> - andb $0x45, %ah
> - jz 2f
> - fxam
> - fnstsw
> - andb $0x45, %ah
> - cmpb $0x40, %ah
> - jne 5f
> - fabs // log2(1) is +0 in all rounding modes.
> -5: fstp %st(1) // x-1 : 1
> - fyl2xp1 // log(x)
> - ret
> -
> -2: fstp %st(0) // x : 1
> - fyl2x // log(x)
> - ret
> -
> -3: jp 4b // in case x is ±Inf
> - fstp %st(1)
> - fstp %st(1)
> - ret
> -END (__ieee754_log2f)
> -strong_alias (__ieee754_log2f, __log2f_finite)
> diff --git a/sysdeps/i386/fpu/e_log2f_data.c b/sysdeps/i386/fpu/e_log2f_data.c
> deleted file mode 100644
> index 1cc8931700..0000000000
> --- a/sysdeps/i386/fpu/e_log2f_data.c
> +++ /dev/null
> @@ -1 +0,0 @@
> -/* Not needed. */
> diff --git a/sysdeps/i386/fpu/libm-test-ulps b/sysdeps/i386/fpu/libm-test-ulps
> index 698d1b3a1d..5318f61146 100644
> --- a/sysdeps/i386/fpu/libm-test-ulps
> +++ b/sysdeps/i386/fpu/libm-test-ulps
> @@ -2300,8 +2300,10 @@ ldouble: 3
>
> Function: "log2":
> double: 1
> +float: 1
> float128: 2
> idouble: 1
> +ifloat: 1
> ifloat128: 2
> ildouble: 1
> ldouble: 1
> diff --git a/sysdeps/i386/fpu/w_log2f.c b/sysdeps/i386/fpu/w_log2f.c
> deleted file mode 100644
> index 3f5c71cec2..0000000000
> --- a/sysdeps/i386/fpu/w_log2f.c
> +++ /dev/null
> @@ -1 +0,0 @@
> -#include <sysdeps/../math/w_log2f.c>
> diff --git a/sysdeps/i386/i686/fpu/multiarch/Makefile b/sysdeps/i386/i686/fpu/multiarch/Makefile
> index ee4c3f39e7..eee3b8b1fd 100644
> --- a/sysdeps/i386/i686/fpu/multiarch/Makefile
> +++ b/sysdeps/i386/i686/fpu/multiarch/Makefile
> @@ -1,8 +1,9 @@
> ifeq ($(subdir),math)
> -libm-sysdep_routines += e_exp2f-sse2 e_expf-sse2 e_logf-sse2 \
> +libm-sysdep_routines += e_exp2f-sse2 e_expf-sse2 e_logf-sse2 e_log2f-sse2 \
> s_sinf-sse2 s_cosf-sse2 s_sincosf-sse2
>
> CFLAGS-e_exp2f-sse2.c = -msse2 -mfpmath=sse
> CFLAGS-e_expf-sse2.c = -msse2 -mfpmath=sse
> +CFLAGS-e_log2f-sse2.c = -msse2 -mfpmath=sse
> CFLAGS-e_logf-sse2.c = -msse2 -mfpmath=sse
> endif
> diff --git a/sysdeps/i386/i686/fpu/multiarch/e_log2f-sse2.c b/sysdeps/i386/i686/fpu/multiarch/e_log2f-sse2.c
> new file mode 100644
> index 0000000000..a9ed25e399
> --- /dev/null
> +++ b/sysdeps/i386/i686/fpu/multiarch/e_log2f-sse2.c
> @@ -0,0 +1,3 @@
> +#define __log2f __log2f_sse2
> +
> +#include <sysdeps/ieee754/flt-32/e_log2f.c>
> diff --git a/sysdeps/i386/i686/fpu/multiarch/e_log2f.c b/sysdeps/i386/i686/fpu/multiarch/e_log2f.c
> new file mode 100644
> index 0000000000..2c4794932a
> --- /dev/null
> +++ b/sysdeps/i386/i686/fpu/multiarch/e_log2f.c
> @@ -0,0 +1,40 @@
> +/* Multiple versions of log2f.
> + Copyright (C) 2017 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
> + <http://www.gnu.org/licenses/>. */
> +
> +extern float __redirect_log2f (float);
> +
> +#define SYMBOL_NAME log2f
> +#include "ifunc-sse2.h"
> +
> +libc_ifunc_redirected (__redirect_log2f, __log2f, IFUNC_SELECTOR ());
> +
> +#ifdef SHARED
> +__hidden_ver1 (__log2f_ia32, __GI___log2f, __redirect_log2f)
> + __attribute__ ((visibility ("hidden")));
> +
> +# include <shlib-compat.h>
> +versioned_symbol (libm, __log2f, log2f, GLIBC_2_27);
> +#else
> +weak_alias (__log2f, log2f)
> +#endif
> +
> +strong_alias (__log2f, __ieee754_log2f)
> +strong_alias (__log2f, __log2f_finite)
> +
> +#define __log2f __log2f_ia32
> +#include <sysdeps/ieee754/flt-32/e_log2f.c>
> diff --git a/sysdeps/i386/i686/fpu/multiarch/libm-test-ulps b/sysdeps/i386/i686/fpu/multiarch/libm-test-ulps
> index c86294b778..b5d74df580 100644
> --- a/sysdeps/i386/i686/fpu/multiarch/libm-test-ulps
> +++ b/sysdeps/i386/i686/fpu/multiarch/libm-test-ulps
> @@ -2300,8 +2300,10 @@ ldouble: 3
>
> Function: "log2":
> double: 1
> +float: 1
> float128: 2
> idouble: 1
> +ifloat: 1
> ifloat128: 2
> ildouble: 1
> ldouble: 1
> --
> 2.13.6
>
--
H.J.