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.

4 files changed, 40 insertions, 5 deletions

diff --git a/sysdeps/powerpc/powerpc64/multiarch/Makefile b/sysdeps/powerpc/powerpc64/multiarch/Makefile
index f5889a3..38233a7 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/Makefile
+++ b/sysdeps/powerpc/powerpc64/multiarch/Makefile
@@ -5,8 +5,9 @@ sysdep_routines += memcpy-power7 memcpy-a2 memcpy-power6 memcpy-cell \
 		   memset-ppc64 memset-power8 \
 		   mempcpy-power7 mempcpy-ppc64 memchr-power7 memchr-ppc64 \
 		   memrchr-power7 memrchr-ppc64 rawmemchr-power7 \
-		   rawmemchr-ppc64 strlen-power7 strlen-ppc64 strnlen-power7 \
-		   strnlen-ppc64 strcasecmp-power7 strcasecmp_l-power7 \
+		   rawmemchr-ppc64 strlen-power7 strlen-ppc64 \
+		   strnlen-power8 strnlen-power7 strnlen-ppc64 \
+		   strcasecmp-power7 strcasecmp_l-power7 \
 		   strncase-power7 strncase_l-power7 \
 		   strncmp-power9 strncmp-power8 strncmp-power7 \
 		   strncmp-power4 strncmp-ppc64 \
diff --git a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
index 209aec5..30a0133 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
@@ -204,6 +204,9 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 
   /* Support sysdeps/powerpc/powerpc64/multiarch/strnlen.c.  */
   IFUNC_IMPL (i, name, strnlen,
+	      IFUNC_IMPL_ADD (array, i, strnlen,
+			      hwcap2 & PPC_FEATURE2_ARCH_2_07,
+			      __strnlen_power8)
 	      IFUNC_IMPL_ADD (array, i, strnlen, hwcap & PPC_FEATURE_HAS_VSX,
 			      __strnlen_power7)
 	      IFUNC_IMPL_ADD (array, i, strnlen, 1,
diff --git a/sysdeps/powerpc/powerpc64/multiarch/strnlen-power8.S b/sysdeps/powerpc/powerpc64/multiarch/strnlen-power8.S
new file mode 100644
index 0000000..ccea15d
--- /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>
diff --git a/sysdeps/powerpc/powerpc64/multiarch/strnlen.c b/sysdeps/powerpc/powerpc64/multiarch/strnlen.c
index 9854c18..7f89132 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/strnlen.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/strnlen.c
@@ -25,12 +25,15 @@
 
 extern __typeof (__strnlen) __strnlen_ppc attribute_hidden;
 extern __typeof (__strnlen) __strnlen_power7 attribute_hidden;
+extern __typeof (__strnlen) __strnlen_power8 attribute_hidden;
 # undef strnlen
 # undef __strnlen
 libc_ifunc_redirected (__redirect___strnlen, __strnlen,
-		       (hwcap & PPC_FEATURE_HAS_VSX)
-		       ? __strnlen_power7
-		       : __strnlen_ppc);
+		       (hwcap2 & PPC_FEATURE2_ARCH_2_07)
+		       ? __strnlen_power8 :
+			 (hwcap & PPC_FEATURE_HAS_VSX)
+			 ? __strnlen_power7
+			 : __strnlen_ppc);
 weak_alias (__strnlen, strnlen)
 
 #else