PowerPC: strncpy/stpncpy optimization for PPC64/POWER7

The optimization is achieved by following techniques:
  > data alignment [gain from aligned memory access on read/write]
  > POWER7 gains performance with loop unrolling/unwinding
    [gain by reduction of branch penalty].
  > zero padding done by calling optimized memset

1 files changed, 35 insertions, 0 deletions

diff --git a/sysdeps/powerpc/powerpc64/multiarch/strncpy.c b/sysdeps/powerpc/powerpc64/multiarch/strncpy.c
new file mode 100644
index 0000000000..8fd5e4b0c8
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/multiarch/strncpy.c
@@ -0,0 +1,35 @@
+/* Multiple versions of strncpy.
+   Copyright (C) 2014 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/ >.  */
+
+/* Define multiple versions only for definition in libc. */
+#ifndef NOT_IN_libc
+# include <string.h>
+# include <shlib-compat.h>
+# include "init-arch.h"
+
+extern __typeof (strncpy) __strncpy_ppc attribute_hidden;
+extern __typeof (strncpy) __strncpy_power7 attribute_hidden;
+
+/* Avoid DWARF definition DIE on ifunc symbol so that GDB can handle
+ ifunc symbol properly. */
+libc_ifunc (strncpy,
+            (hwcap & PPC_FEATURE_HAS_VSX)
+            ? __strncpy_power7
+            : __strncpy_ppc);
+
+#endif