powerpc64: Add POWER8 strnlen

Added strnlen POWER8 otimized for long strings. It delivers
same performance as POWER7 implementation for short strings.

This takes advantage of reasonably performing unaligned loads
and bit permutes to check the first 1-16 bytes until
quadword aligned, then checks in 64 bytes strides until unsafe,
then 16 bytes, truncating the count if need be.

Likewise, the POWER7 code is recycled for less than 32 bytes strings.

Tested on ppc64 and ppc64le.

	* sysdeps/powerpc/powerpc64/multiarch/Makefile
	(sysdep_routines): Add strnlen-power8.
	* sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
	(strnlen): Add __strnlen_power8 to list of strnlen functions.
	* sysdeps/powerpc/powerpc64/multiarch/strnlen-power8.S:
	New file.
	* sysdeps/powerpc/powerpc64/multiarch/strnlen.c
	(__strnlen): Add __strnlen_power8 to ifunc list.
	* sysdeps/powerpc/powerpc64/power8/strnlen.S: New file.

1 files changed, 28 insertions, 0 deletions

diff --git a/sysdeps/powerpc/powerpc64/multiarch/strnlen-power8.S b/sysdeps/powerpc/powerpc64/multiarch/strnlen-power8.S
new file mode 100644
index 0000000000..ccea15df10
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/multiarch/strnlen-power8.S
@@ -0,0 +1,28 @@
+/* Optimized strnlen version for POWER8.
+   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/>.  */
+
+#include <sysdep.h>
+
+#define __strnlen __strnlen_power8
+
+#undef libc_hidden_builtin_def
+#define libc_hidden_builtin_def(name)
+#undef weak_alias
+#define weak_alias(name, alias)
+
+#include <sysdeps/powerpc/powerpc64/power8/strnlen.S>