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x86_64: Add log2 with FMA

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On Skylake, it improves log2 bench performance by:

        Before       After     Improvement
max     208.779      63.827       69%
min     9.977        6.55         34%
mean    10.366       6.8191       34%
This commit is contained in:
H.J. Lu 2023-08-10 11:24:30 -07:00
parent 542b110585
commit f6b10ed8e9
3 changed files with 48 additions and 0 deletions
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2
sysdeps/x86_64/fpu/multiarch/Makefile
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@ -34,6 +34,7 @@ libm-sysdep_routines += \
e_atan2-fma \ e_atan2-fma \
e_exp-fma \ e_exp-fma \
e_log-fma \ e_log-fma \
e_log2-fma \
e_pow-fma \ e_pow-fma \
s_atan-fma \ s_atan-fma \
s_sin-fma \ s_sin-fma \
@ -45,6 +46,7 @@ CFLAGS-e_asin-fma.c = -mfma -mavx2
CFLAGS-e_atan2-fma.c = -mfma -mavx2 CFLAGS-e_atan2-fma.c = -mfma -mavx2
CFLAGS-e_exp-fma.c = -mfma -mavx2 CFLAGS-e_exp-fma.c = -mfma -mavx2
CFLAGS-e_log-fma.c = -mfma -mavx2 CFLAGS-e_log-fma.c = -mfma -mavx2
CFLAGS-e_log2-fma.c = -mfma -mavx2
CFLAGS-e_pow-fma.c = -mfma -mavx2 CFLAGS-e_pow-fma.c = -mfma -mavx2
CFLAGS-s_atan-fma.c = -mfma -mavx2 CFLAGS-s_atan-fma.c = -mfma -mavx2
CFLAGS-s_sin-fma.c = -mfma -mavx2 CFLAGS-s_sin-fma.c = -mfma -mavx2

3
sysdeps/x86_64/fpu/multiarch/e_log2-fma.c Normal file
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@ -0,0 +1,3 @@
#define __log2 __log2_fma
#include <sysdeps/ieee754/dbl-64/e_log2.c>

43
sysdeps/x86_64/fpu/multiarch/e_log2.c Normal file
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@ -0,0 +1,43 @@
/* Multiple versions of log2.
Copyright (C) 2023 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>
#include <libm-alias-finite.h>
extern double __redirect_log2 (double);
#define SYMBOL_NAME log2
#include "ifunc-fma.h"
libc_ifunc_redirected (__redirect_log2, __log2, IFUNC_SELECTOR ());
#ifdef SHARED
__hidden_ver1 (__log2, __GI___log2, __redirect_log2)
__attribute__ ((visibility ("hidden")));
versioned_symbol (libm, __ieee754_log2, log2, GLIBC_2_29);
libm_alias_double_other (__log2, log2)
#else
libm_alias_double (__log2, log2)
#endif
strong_alias (__log2, __ieee754_log2)
libm_alias_finite (__log2, __log2)
#define __log2 __log2_sse2
#include <sysdeps/ieee754/dbl-64/e_log2.c>