powerpc: Add a POWER8-optimized version of expf()

This implementation is based on the one already used at
sysdeps/x86_64/fpu/e_expf.S.

This implementation improves the performance by ~14% on average in synthetic
benchmarks at the cost of decreasing accuracy to 1 ULP.

1 files changed, 26 insertions, 0 deletions

diff --git a/sysdeps/powerpc/powerpc64/fpu/multiarch/e_expf-power8.S b/sysdeps/powerpc/powerpc64/fpu/multiarch/e_expf-power8.S
new file mode 100644
index 0000000000..02eff243e1
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/fpu/multiarch/e_expf-power8.S
@@ -0,0 +1,26 @@
+/* __ieee754_expf() POWER8 version.
+   Copyright (C) 2016 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/>.  */
+
+#include <sysdep.h>
+
+#undef strong_alias
+#define strong_alias(a, b)
+
+#define __ieee754_expf __ieee754_expf_power8
+
+#include <sysdeps/powerpc/powerpc64/power8/fpu/e_expf.S>