powerpc: Optimize memrchr for power8

Vectorized loops are used for sizes greater than 32B to improve
performance over power7 optimization.  This shows as an average
of 25% improvement depending on the position of search
character.  The performance is same for shorter strings.

ChangeLog

@@ -1,3 +1,15 @@
+2017-10-02  Rajalakshmi Srinivasaraghavan  <[email protected]>
+
+	* sysdeps/powerpc/powerpc64/multiarch/Makefile
+	(sysdep_routines): Add memrchr_power8.
+	* sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
+	(memrchr): Add __memrchr_power8 to list of memrchr functions.
+	* sysdeps/powerpc/powerpc64/multiarch/memrchr-power8.S:
+	New file.
+	* sysdeps/powerpc/powerpc64/multiarch/memrchr.c
+	(memrchr): Add __memrchr_power8 to ifunc list.
+	* sysdeps/powerpc/powerpc64/power8/memrchr.S: New file.
+
 2017-10-01  H.J. Lu  <[email protected]>
 
 	[BZ #18822]

sysdeps/powerpc/powerpc64/multiarch/Makefile

@@ -6,8 +6,9 @@ sysdep_routines += memcpy-power7 memcpy-a2 memcpy-power6 memcpy-cell \
 		   memset-ppc64 memset-power8 \
 		   mempcpy-power7 mempcpy-ppc64 \
 		   memchr-power8 memchr-power7 memchr-ppc64 \
-		   memrchr-power7 memrchr-ppc64 rawmemchr-power7 \
-		   rawmemchr-ppc64 strlen-power7 strlen-ppc64 \
+		   memrchr-power8 memrchr-power7 memrchr-ppc64 \
+		   rawmemchr-power7 rawmemchr-ppc64 \
+		   strlen-power7 strlen-ppc64 \
 		   strnlen-power8 strnlen-power7 strnlen-ppc64 \
 		   strcasecmp-power7 strcasecmp_l-power7 \
 		   strncase-power7 strncase_l-power7 \

sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c

@@ -193,6 +193,9 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 
   /* Support sysdeps/powerpc/powerpc64/multiarch/memrchr.c.  */
   IFUNC_IMPL (i, name, memrchr,
+	      IFUNC_IMPL_ADD (array, i, memrchr,
+			      hwcap2 & PPC_FEATURE2_ARCH_2_07,
+			      __memrchr_power8)
 	      IFUNC_IMPL_ADD (array, i, memrchr,
 			      hwcap & PPC_FEATURE_HAS_VSX,
 			      __memrchr_power7)

sysdeps/powerpc/powerpc64/multiarch/memrchr-power8.S

@@ -0,0 +1,28 @@
+/* Optimized memrchr implementation for PowerPC64/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 MEMRCHR __memrchr_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/memrchr.S>

sysdeps/powerpc/powerpc64/multiarch/memrchr-ppc64.c

@@ -16,4 +16,16 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <sysdeps/powerpc/powerpc32/power4/multiarch/memrchr-ppc32.c>
+#include <string.h>
+
+#define MEMRCHR  __memrchr_ppc
+
+#undef weak_alias
+#define weak_alias(a, b)
+
+#undef libc_hidden_builtin_def
+#define libc_hidden_builtin_def(name)
+
+extern __typeof (memrchr) __memrchr_ppc attribute_hidden;
+
+#include <string/memrchr.c>