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authorH.J. Lu <hjl.tools@gmail.com>2023-08-17 09:42:29 -0700
committerH.J. Lu <hjl.tools@gmail.com>2023-08-21 10:44:26 -0700
commita8ecb126d4c26c52f4ad828c566afe4043a28155 (patch)
treebfab51ea467c0717fc322be816770598edfcca63 /sysdeps/x86_64/fpu
parentce99601fa883a8916cb902c7bcd2125046a4a39d (diff)
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x86_64: Add log1p with FMA
On Skylake, it changes log1p bench performance by: Before After Improvement max 63.349 58.347 8% min 4.448 5.651 -30% mean 12.0674 10.336 14% The minimum code path is if (hx < 0x3FDA827A) /* x < 0.41422 */ { if (__glibc_unlikely (ax >= 0x3ff00000)) /* x <= -1.0 */ { ... } if (__glibc_unlikely (ax < 0x3e200000)) /* |x| < 2**-29 */ { math_force_eval (two54 + x); /* raise inexact */ if (ax < 0x3c900000) /* |x| < 2**-54 */ { ... } else return x - x * x * 0.5; FMA and non-FMA code sequences look similar. Non-FMA version is slightly faster. Since log1p is called by asinh and atanh, it improves asinh performance by: Before After Improvement max 75.645 63.135 16% min 10.074 10.071 0% mean 15.9483 14.9089 6% and improves atanh performance by: Before After Improvement max 91.768 75.081 18% min 15.548 13.883 10% mean 18.3713 16.8011 8%
Diffstat (limited to 'sysdeps/x86_64/fpu')
-rw-r--r--sysdeps/x86_64/fpu/multiarch/Makefile2
-rw-r--r--sysdeps/x86_64/fpu/multiarch/s_log1p-fma.c4
-rw-r--r--sysdeps/x86_64/fpu/multiarch/s_log1p.c29
3 files changed, 35 insertions, 0 deletions
diff --git a/sysdeps/x86_64/fpu/multiarch/Makefile b/sysdeps/x86_64/fpu/multiarch/Makefile
index add339a..ea81753 100644
--- a/sysdeps/x86_64/fpu/multiarch/Makefile
+++ b/sysdeps/x86_64/fpu/multiarch/Makefile
@@ -38,6 +38,7 @@ libm-sysdep_routines += \
e_pow-fma \
s_atan-fma \
s_expm1-fma \
+ s_log1p-fma \
s_sin-fma \
s_sincos-fma \
s_tan-fma \
@@ -51,6 +52,7 @@ CFLAGS-e_log2-fma.c = -mfma -mavx2
CFLAGS-e_pow-fma.c = -mfma -mavx2
CFLAGS-s_atan-fma.c = -mfma -mavx2
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_sincos-fma.c = -mfma -mavx2
diff --git a/sysdeps/x86_64/fpu/multiarch/s_log1p-fma.c b/sysdeps/x86_64/fpu/multiarch/s_log1p-fma.c
new file mode 100644
index 0000000..8952df8
--- /dev/null
+++ b/sysdeps/x86_64/fpu/multiarch/s_log1p-fma.c
@@ -0,0 +1,4 @@
+#define __log1p __log1p_fma
+#define SECTION __attribute__ ((section (".text.fma")))
+
+#include <sysdeps/ieee754/dbl-64/s_log1p.c>
diff --git a/sysdeps/x86_64/fpu/multiarch/s_log1p.c b/sysdeps/x86_64/fpu/multiarch/s_log1p.c
new file mode 100644
index 0000000..6ce5198
--- /dev/null
+++ b/sysdeps/x86_64/fpu/multiarch/s_log1p.c
@@ -0,0 +1,29 @@
+/* Multiple versions of log1p.
+ 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>
+
+extern double __redirect_log1p (double);
+
+#define SYMBOL_NAME log1p
+#include "ifunc-fma.h"
+
+libc_ifunc_redirected (__redirect_log1p, __log1p, IFUNC_SELECTOR ());
+
+#define __log1p __log1p_sse2
+#include <sysdeps/ieee754/dbl-64/s_log1p.c>