powerpc: Optimized strcmp for POWER8/PPC64

This patch adds an optimized POWER8 strcmp using unaligned accesses.
The algorithm first check the initial 16 bytes, then align the first
function source and uses unaligned loads on second argument only.
Aditional checks for page boundaries are done for unaligned cases

4 files changed, 49 insertions, 3 deletions

diff --git a/sysdeps/powerpc/powerpc64/multiarch/Makefile b/sysdeps/powerpc/powerpc64/multiarch/Makefile
index 18d337843c..ec4fca7c59 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/Makefile
+++ b/sysdeps/powerpc/powerpc64/multiarch/Makefile
@@ -18,7 +18,7 @@ sysdep_routines += memcpy-power7 memcpy-a2 memcpy-power6 memcpy-cell \
 		   strrchr-power7 strrchr-ppc64 strncat-power7 strncat-ppc64 \
 		   strncpy-power7 strncpy-ppc64 \
 		   stpncpy-power8 stpncpy-power7 stpncpy-ppc64 \
-		   strcmp-power7 strcmp-ppc64 \
+		   strcmp-power8 strcmp-power7 strcmp-ppc64 \
 		   strcat-power8 strcat-power7 strcat-ppc64 memmove-power7 \
 		   memmove-ppc64 bcopy-ppc64 strncpy-power8
 
diff --git a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
index 132cb13eac..2c03060d4e 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
@@ -301,6 +301,9 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   /* Support sysdeps/powerpc/powerpc64/multiarch/strcmp.c.  */
   IFUNC_IMPL (i, name, strcmp,
 	      IFUNC_IMPL_ADD (array, i, strcmp,
+			      hwcap2 & PPC_FEATURE2_ARCH_2_07,
+			      __strcmp_power8)
+	      IFUNC_IMPL_ADD (array, i, strcmp,
 			      hwcap & PPC_FEATURE_HAS_VSX,
 			      __strcmp_power7)
 	      IFUNC_IMPL_ADD (array, i, strcmp, 1,
diff --git a/sysdeps/powerpc/powerpc64/multiarch/strcmp-power8.S b/sysdeps/powerpc/powerpc64/multiarch/strcmp-power8.S
new file mode 100644
index 0000000000..dc4bfac9ee
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/multiarch/strcmp-power8.S
@@ -0,0 +1,40 @@
+/* Optimized strcmp implementation for POWER8/PPC64.
+   Copyright (C) 2015 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 EALIGN
+#define EALIGN(name, alignt, words)				\
+  .section ".text";						\
+  ENTRY_2(__strcmp_power8)					\
+  .align ALIGNARG(alignt);					\
+  EALIGN_W_##words;						\
+  BODY_LABEL(__strcmp_power8):					\
+  cfi_startproc;						\
+  LOCALENTRY(__strcmp_power8)
+
+#undef END
+#define END(name)						\
+  cfi_endproc;							\
+  TRACEBACK(__strcmp_power8)					\
+  END_2(__strcmp_power8)
+
+#undef libc_hidden_builtin_def
+#define libc_hidden_builtin_def(name)
+
+#include <sysdeps/powerpc/powerpc64/power8/strcmp.S>
diff --git a/sysdeps/powerpc/powerpc64/multiarch/strcmp.c b/sysdeps/powerpc/powerpc64/multiarch/strcmp.c
index 9b2922f644..b45ba1f54d 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/strcmp.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/strcmp.c
@@ -23,9 +23,12 @@
 
 extern __typeof (strcmp) __strcmp_ppc attribute_hidden;
 extern __typeof (strcmp) __strcmp_power7 attribute_hidden;
+extern __typeof (strcmp) __strcmp_power8 attribute_hidden;
 
 libc_ifunc (strcmp,
-            (hwcap & PPC_FEATURE_HAS_VSX)
-            ? __strcmp_power7
+            (hwcap2 & PPC_FEATURE2_ARCH_2_07)
+              ? __strcmp_power8 :
+              (hwcap & PPC_FEATURE_HAS_VSX)
+              ? __strcmp_power7
             : __strcmp_ppc);
 #endif