From d360e53aa1a658930e143b4dec85cb81c18e65cc Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Sun, 11 Jun 2017 06:18:32 -0700
Subject: [PATCH] x86-64: Implement strcpy family IFUNC selectors in C

Implement strcpy family IFUNC selectors in C.

All internal calls within libc.so can use IFUNC on x86-64 since unlike
x86, x86-64 supports PC-relative addressing to access the GOT entry so
that it can call via PLT without using an extra register.  For libc.a,
we can't use IFUNC for functions which are called before IFUNC has been
initialized.  Use IFUNC internally reduces the icache footprint since
libc.so and other codes in the process use the same implementations.
This patch uses IFUNC for strcpy family functions within libc.

	* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add
	strcpy-sse2 and stpcpy-sse2.
	* sysdeps/x86_64/multiarch/ifunc-unaligned-ssse3.h: New file.
	* sysdeps/x86_64/multiarch/stpcpy-sse2.S: Likewise.
	* sysdeps/x86_64/multiarch/stpcpy.c: Likewise.
	* sysdeps/x86_64/multiarch/stpncpy.c: Likewise.
	* sysdeps/x86_64/multiarch/strcpy-sse2.S: Likewise.
	* sysdeps/x86_64/multiarch/strcpy.c: Likewise.
	* sysdeps/x86_64/multiarch/strncpy.c: Likewise.
	* sysdeps/x86_64/multiarch/stpcpy.S: Removed.
	* sysdeps/x86_64/multiarch/stpncpy.S: Likewise.
	* sysdeps/x86_64/multiarch/strcpy.S: Likewise.
	* sysdeps/x86_64/multiarch/strncpy.S: Likewise.
	* sysdeps/x86_64/multiarch/stpncpy-c.c (weak_alias): New.
	(libc_hidden_def): Always defined as empty.
	* sysdeps/x86_64/multiarch/strncpy-c.c (libc_hidden_builtin_def):
	Always Defined as empty.
---
 sysdeps/x86_64/multiarch/Makefile                |  1 +
 sysdeps/x86_64/multiarch/ifunc-unaligned-ssse3.h | 40 ++++++++++
 sysdeps/x86_64/multiarch/stpcpy-sse2.S           | 33 ++++++++
 sysdeps/x86_64/multiarch/stpcpy.S                |  9 ---
 sysdeps/x86_64/multiarch/stpcpy.c                | 41 ++++++++++
 sysdeps/x86_64/multiarch/stpncpy-c.c             |  9 +--
 sysdeps/x86_64/multiarch/stpncpy.S               |  8 --
 sysdeps/x86_64/multiarch/stpncpy.c               | 38 +++++++++
 sysdeps/x86_64/multiarch/strcpy-sse2.S           | 28 +++++++
 sysdeps/x86_64/multiarch/strcpy.S                | 99 ------------------------
 sysdeps/x86_64/multiarch/strcpy.c                | 35 +++++++++
 sysdeps/x86_64/multiarch/strncpy-c.c             |  7 +-
 sysdeps/x86_64/multiarch/strncpy.S               |  5 --
 sysdeps/x86_64/multiarch/strncpy.c               | 36 +++++++++
 14 files changed, 258 insertions(+), 131 deletions(-)
 create mode 100644 sysdeps/x86_64/multiarch/ifunc-unaligned-ssse3.h
 create mode 100644 sysdeps/x86_64/multiarch/stpcpy-sse2.S
 delete mode 100644 sysdeps/x86_64/multiarch/stpcpy.S
 create mode 100644 sysdeps/x86_64/multiarch/stpcpy.c
 delete mode 100644 sysdeps/x86_64/multiarch/stpncpy.S
 create mode 100644 sysdeps/x86_64/multiarch/stpncpy.c
 create mode 100644 sysdeps/x86_64/multiarch/strcpy-sse2.S
 delete mode 100644 sysdeps/x86_64/multiarch/strcpy.S
 create mode 100644 sysdeps/x86_64/multiarch/strcpy.c
 delete mode 100644 sysdeps/x86_64/multiarch/strncpy.S
 create mode 100644 sysdeps/x86_64/multiarch/strncpy.c

diff --git a/sysdeps/x86_64/multiarch/Makefile b/sysdeps/x86_64/multiarch/Makefile
index 7d7c142..ff6c7f4 100644
--- a/sysdeps/x86_64/multiarch/Makefile
+++ b/sysdeps/x86_64/multiarch/Makefile
@@ -19,6 +19,7 @@ sysdep_routines += strncat-c stpncpy-c strncpy-c strcmp-ssse3 \
 		   strrchr-sse2 strrchr-avx2 \
 		   strlen-sse2 strnlen-sse2 strlen-avx2 strnlen-avx2 \
 		   strncase_l-ssse3 strcat-ssse3 strncat-ssse3\
+		   strcpy-sse2 stpcpy-sse2 \
 		   strcpy-ssse3 strncpy-ssse3 stpcpy-ssse3 stpncpy-ssse3 \
 		   strcpy-sse2-unaligned strncpy-sse2-unaligned \
 		   stpcpy-sse2-unaligned stpncpy-sse2-unaligned \
diff --git a/sysdeps/x86_64/multiarch/ifunc-unaligned-ssse3.h b/sysdeps/x86_64/multiarch/ifunc-unaligned-ssse3.h
new file mode 100644
index 0000000..5e7c47d
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/ifunc-unaligned-ssse3.h
@@ -0,0 +1,40 @@
+/* Common definition for ifunc selections optimized with SSE2, unaligned
+   SSE2 and SSSE3.
+   All versions must be listed in ifunc-impl-list.c.
+   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 <init-arch.h>
+
+extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2_unaligned)
+  attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE (ssse3) attribute_hidden;
+
+static inline void *
+IFUNC_SELECTOR (void)
+{
+  const struct cpu_features* cpu_features = __get_cpu_features ();
+
+  if (CPU_FEATURES_ARCH_P (cpu_features, Fast_Unaligned_Load))
+    return OPTIMIZE (sse2_unaligned);
+
+  if (CPU_FEATURES_CPU_P (cpu_features, SSSE3))
+    return OPTIMIZE (ssse3);
+
+  return OPTIMIZE (sse2);
+}
diff --git a/sysdeps/x86_64/multiarch/stpcpy-sse2.S b/sysdeps/x86_64/multiarch/stpcpy-sse2.S
new file mode 100644
index 0000000..10d6cc7
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/stpcpy-sse2.S
@@ -0,0 +1,33 @@
+/* stpcpy optimized with SSE2.
+   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/>.  */
+
+#if IS_IN (libc)
+
+# include <sysdep.h>
+# define __stpcpy __stpcpy_sse2
+
+# undef weak_alias
+# define weak_alias(ignored1, ignored2)
+# undef libc_hidden_def
+# define libc_hidden_def(__stpcpy)
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(stpcpy)
+#endif
+
+#define USE_AS_STPCPY
+#include <sysdeps/x86_64/stpcpy.S>
diff --git a/sysdeps/x86_64/multiarch/stpcpy.S b/sysdeps/x86_64/multiarch/stpcpy.S
deleted file mode 100644
index ee81ab6..0000000
--- a/sysdeps/x86_64/multiarch/stpcpy.S
+++ /dev/null
@@ -1,9 +0,0 @@
-/* Multiple versions of stpcpy
-   All versions must be listed in ifunc-impl-list.c.  */
-#define USE_AS_STPCPY
-#define STRCPY __stpcpy
-#include "strcpy.S"
-
-weak_alias (__stpcpy, stpcpy)
-libc_hidden_def (__stpcpy)
-libc_hidden_builtin_def (stpcpy)
diff --git a/sysdeps/x86_64/multiarch/stpcpy.c b/sysdeps/x86_64/multiarch/stpcpy.c
new file mode 100644
index 0000000..7043584
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/stpcpy.c
@@ -0,0 +1,41 @@
+/* Multiple versions of stpcpy.
+   All versions must be listed in ifunc-impl-list.c.
+   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/>.  */
+
+/* Define multiple versions only for the definition in libc.  */
+#if IS_IN (libc)
+# define _HAVE_STRING_ARCH_stpcpy 1
+# define stpcpy __redirect_stpcpy
+# define __stpcpy __redirect___stpcpy
+# include <string.h>
+# undef stpcpy
+# undef __stpcpy
+
+# define SYMBOL_NAME stpcpy
+# include "ifunc-unaligned-ssse3.h"
+
+libc_ifunc_redirected (__redirect_stpcpy, __stpcpy, IFUNC_SELECTOR ());
+
+weak_alias (__stpcpy, stpcpy)
+# ifdef SHARED
+__hidden_ver1 (__stpcpy, __GI___stpcpy, __redirect___stpcpy)
+  __attribute__ ((visibility ("hidden")));
+__hidden_ver1 (stpcpy, __GI_stpcpy, __redirect_stpcpy)
+  __attribute__ ((visibility ("hidden")));
+# endif
+#endif
diff --git a/sysdeps/x86_64/multiarch/stpncpy-c.c b/sysdeps/x86_64/multiarch/stpncpy-c.c
index 2fde77d..b016e48 100644
--- a/sysdeps/x86_64/multiarch/stpncpy-c.c
+++ b/sysdeps/x86_64/multiarch/stpncpy-c.c
@@ -1,8 +1,7 @@
 #define STPNCPY __stpncpy_sse2
-#ifdef SHARED
+#undef weak_alias
+#define weak_alias(ignored1, ignored2)
 #undef libc_hidden_def
-#define libc_hidden_def(name) \
-  __hidden_ver1 (__stpncpy_sse2, __GI___stpncpy, __stpncpy_sse2);
-#endif
+#define libc_hidden_def(stpncpy)
 
-#include "stpncpy.c"
+#include <string/stpncpy.c>
diff --git a/sysdeps/x86_64/multiarch/stpncpy.S b/sysdeps/x86_64/multiarch/stpncpy.S
deleted file mode 100644
index 2698ca6..0000000
--- a/sysdeps/x86_64/multiarch/stpncpy.S
+++ /dev/null
@@ -1,8 +0,0 @@
-/* Multiple versions of stpncpy
-   All versions must be listed in ifunc-impl-list.c.  */
-#define STRCPY __stpncpy
-#define USE_AS_STPCPY
-#define USE_AS_STRNCPY
-#include "strcpy.S"
-
-weak_alias (__stpncpy, stpncpy)
diff --git a/sysdeps/x86_64/multiarch/stpncpy.c b/sysdeps/x86_64/multiarch/stpncpy.c
new file mode 100644
index 0000000..36d5b4b
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/stpncpy.c
@@ -0,0 +1,38 @@
+/* Multiple versions of stpncpy.
+   All versions must be listed in ifunc-impl-list.c.
+   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/>.  */
+
+/* Define multiple versions only for the definition in libc.  */
+#if IS_IN (libc)
+# define stpncpy __redirect_stpncpy
+# define __stpncpy __redirect___stpncpy
+# include <string.h>
+# undef stpncpy
+# undef __stpncpy
+
+# define SYMBOL_NAME stpncpy
+# include "ifunc-unaligned-ssse3.h"
+
+libc_ifunc_redirected (__redirect_stpncpy, __stpncpy, IFUNC_SELECTOR ());
+
+weak_alias (__stpncpy, stpncpy)
+# ifdef SHARED
+__hidden_ver1 (__stpncpy, __GI___stpncpy, __redirect___stpncpy)
+  __attribute__ ((visibility ("hidden")));
+# endif
+#endif
diff --git a/sysdeps/x86_64/multiarch/strcpy-sse2.S b/sysdeps/x86_64/multiarch/strcpy-sse2.S
new file mode 100644
index 0000000..ee7cbbf
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strcpy-sse2.S
@@ -0,0 +1,28 @@
+/* strcpy optimized with SSE2.
+   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/>.  */
+
+#if IS_IN (libc)
+
+# include <sysdep.h>
+# define strcpy __strcpy_sse2
+
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(strcpy)
+#endif
+
+#include <sysdeps/x86_64/strcpy.S>
diff --git a/sysdeps/x86_64/multiarch/strcpy.S b/sysdeps/x86_64/multiarch/strcpy.S
deleted file mode 100644
index 77819dd..0000000
--- a/sysdeps/x86_64/multiarch/strcpy.S
+++ /dev/null
@@ -1,99 +0,0 @@
-/* Multiple versions of strcpy
-   All versions must be listed in ifunc-impl-list.c.
-   Copyright (C) 2009-2017 Free Software Foundation, Inc.
-   Contributed by Intel Corporation.
-   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>
-#include <init-arch.h>
-
-#if !defined (USE_AS_STPCPY) && !defined (USE_AS_STRNCPY)
-# ifndef STRCPY
-#  define STRCPY strcpy
-# endif
-#endif
-
-#ifdef USE_AS_STPCPY
-# ifdef USE_AS_STRNCPY
-#  define STRCPY_SSSE3		__stpncpy_ssse3
-#  define STRCPY_SSE2		__stpncpy_sse2
-#  define STRCPY_SSE2_UNALIGNED __stpncpy_sse2_unaligned
-#  define __GI_STRCPY		__GI_stpncpy
-#  define __GI___STRCPY		__GI___stpncpy
-# else
-#  define STRCPY_SSSE3		__stpcpy_ssse3
-#  define STRCPY_SSE2		__stpcpy_sse2
-#  define STRCPY_SSE2_UNALIGNED	__stpcpy_sse2_unaligned
-#  define __GI_STRCPY		__GI_stpcpy
-#  define __GI___STRCPY		__GI___stpcpy
-# endif
-#else
-# ifdef USE_AS_STRNCPY
-#  define STRCPY_SSSE3		__strncpy_ssse3
-#  define STRCPY_SSE2		__strncpy_sse2
-#  define STRCPY_SSE2_UNALIGNED	__strncpy_sse2_unaligned
-#  define __GI_STRCPY		__GI_strncpy
-# else
-#  define STRCPY_SSSE3		__strcpy_ssse3
-#  define STRCPY_SSE2		__strcpy_sse2
-#  define STRCPY_SSE2_UNALIGNED	__strcpy_sse2_unaligned
-#  define __GI_STRCPY		__GI_strcpy
-# endif
-#endif
-
-
-/* Define multiple versions only for the definition in libc.  */
-#if IS_IN (libc)
-	.text
-ENTRY(STRCPY)
-	.type	STRCPY, @gnu_indirect_function
-	LOAD_RTLD_GLOBAL_RO_RDX
-	leaq	STRCPY_SSE2_UNALIGNED(%rip), %rax
-	HAS_ARCH_FEATURE (Fast_Unaligned_Load)
-	jnz	2f
-	leaq	STRCPY_SSE2(%rip), %rax
-	HAS_CPU_FEATURE (SSSE3)
-	jz	2f
-	leaq	STRCPY_SSSE3(%rip), %rax
-2:	ret
-END(STRCPY)
-
-# undef ENTRY
-# define ENTRY(name) \
-	.type STRCPY_SSE2, @function; \
-	.align 16; \
-	.globl STRCPY_SSE2; \
-	.hidden STRCPY_SSE2; \
-	STRCPY_SSE2: cfi_startproc; \
-	CALL_MCOUNT
-# undef END
-# define END(name) \
-	cfi_endproc; .size STRCPY_SSE2, .-STRCPY_SSE2
-# undef libc_hidden_builtin_def
-/* It doesn't make sense to send libc-internal strcpy calls through a PLT.
-   The speedup we get from using SSSE3 instruction is likely eaten away
-   by the indirect call in the PLT.  */
-# define libc_hidden_builtin_def(name) \
-	.globl __GI_STRCPY; __GI_STRCPY = STRCPY_SSE2
-# undef libc_hidden_def
-# define libc_hidden_def(name) \
-	.globl __GI___STRCPY; __GI___STRCPY = STRCPY_SSE2
-#endif
-
-#ifndef USE_AS_STRNCPY
-#include "../strcpy.S"
-#endif
diff --git a/sysdeps/x86_64/multiarch/strcpy.c b/sysdeps/x86_64/multiarch/strcpy.c
new file mode 100644
index 0000000..d8757df
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strcpy.c
@@ -0,0 +1,35 @@
+/* Multiple versions of strcpy.
+   All versions must be listed in ifunc-impl-list.c.
+   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/>.  */
+
+/* Define multiple versions only for the definition in libc.  */
+#if IS_IN (libc)
+# define strcpy __redirect_strcpy
+# include <string.h>
+# undef strcpy
+
+# define SYMBOL_NAME strcpy
+# include "ifunc-unaligned-ssse3.h"
+
+libc_ifunc_redirected (__redirect_strcpy, strcpy, IFUNC_SELECTOR ());
+
+# ifdef SHARED
+__hidden_ver1 (strcpy, __GI_strcpy, __redirect_strcpy)
+  __attribute__ ((visibility ("hidden")));
+# endif
+#endif
diff --git a/sysdeps/x86_64/multiarch/strncpy-c.c b/sysdeps/x86_64/multiarch/strncpy-c.c
index 296c32c..57c45ac 100644
--- a/sysdeps/x86_64/multiarch/strncpy-c.c
+++ b/sysdeps/x86_64/multiarch/strncpy-c.c
@@ -1,8 +1,5 @@
 #define STRNCPY __strncpy_sse2
-#ifdef SHARED
 #undef libc_hidden_builtin_def
-#define libc_hidden_builtin_def(name) \
-  __hidden_ver1 (__strncpy_sse2, __GI_strncpy, __strncpy_sse2);
-#endif
+#define libc_hidden_builtin_def(strncpy)
 
-#include "strncpy.c"
+#include <string/strncpy.c>
diff --git a/sysdeps/x86_64/multiarch/strncpy.S b/sysdeps/x86_64/multiarch/strncpy.S
deleted file mode 100644
index 6d87a0b..0000000
--- a/sysdeps/x86_64/multiarch/strncpy.S
+++ /dev/null
@@ -1,5 +0,0 @@
-/* Multiple versions of strncpy
-   All versions must be listed in ifunc-impl-list.c.  */
-#define STRCPY strncpy
-#define USE_AS_STRNCPY
-#include "strcpy.S"
diff --git a/sysdeps/x86_64/multiarch/strncpy.c b/sysdeps/x86_64/multiarch/strncpy.c
new file mode 100644
index 0000000..7b71cb9
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/strncpy.c
@@ -0,0 +1,36 @@
+/* Multiple versions of strncpy.
+   All versions must be listed in ifunc-impl-list.c.
+   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/>.  */
+
+/* Define multiple versions only for the definition in libc.  */
+#if IS_IN (libc)
+# define _HAVE_STRING_ARCH_strncpy 1
+# define strncpy __redirect_strncpy
+# include <string.h>
+# undef strncpy
+
+# define SYMBOL_NAME strncpy
+# include "ifunc-unaligned-ssse3.h"
+
+libc_ifunc_redirected (__redirect_strncpy, strncpy, IFUNC_SELECTOR ());
+
+# ifdef SHARED
+__hidden_ver1 (strncpy, __GI_strncpy, __redirect_strncpy)
+  __attribute__ ((visibility ("hidden")));
+# endif
+#endif
-- 
2.9.4
