S390: Refactor wcsncpy ifunc handling.

The ifunc handling for wcsncpy is adjusted in order to omit ifunc
if the minimum architecture level already supports newer CPUs by default.
Unfortunately the c ifunc variant can't be omitted at all as it is used
by the z13 ifunc variant as fallback if the pointers are not 4-byte aligned.

ChangeLog:

	* sysdeps/s390/multiarch/Makefile
	(sysdep_routines): Remove wcsncpy variants.
	* sysdeps/s390/Makefile (sysdep_routines): Add wcsncpy variants.
	* sysdeps/s390/multiarch/ifunc-impl-list.c
	(__libc_ifunc_impl_list): Refactor ifunc handling for wcsncpy.
	* sysdeps/s390/multiarch/wcsncpy-c.c: Move to ...
	* sysdeps/s390/wcsncpy-c.c: ... here and adjust ifunc handling.
	* sysdeps/s390/multiarch/wcsncpy-vx.S: Move to ...
	* sysdeps/s390/wcsncpy-vx.S: ... here and adjust ifunc handling.
	* sysdeps/s390/multiarch/wcsncpy.c: Move to ...
	* sysdeps/s390/wcsncpy.c: ... here and adjust ifunc handling.
	* sysdeps/s390/ifunc-wcsncpy.h: New file.

7 files changed, 103 insertions, 21 deletions

diff --git a/sysdeps/s390/Makefile b/sysdeps/s390/Makefile
index 0fc0cdaee9..e10ad5b470 100644
--- a/sysdeps/s390/Makefile
+++ b/sysdeps/s390/Makefile
@@ -86,5 +86,6 @@ ifeq ($(subdir),wcsmbs)
 sysdep_routines += wcslen wcslen-vx wcslen-c \
 		   wcsnlen wcsnlen-vx wcsnlen-c \
 		   wcscpy wcscpy-vx wcscpy-c \
-		   wcpcpy wcpcpy-vx wcpcpy-c
+		   wcpcpy wcpcpy-vx wcpcpy-c \
+		   wcsncpy wcsncpy-vx wcsncpy-c
 endif
diff --git a/sysdeps/s390/ifunc-wcsncpy.h b/sysdeps/s390/ifunc-wcsncpy.h
new file mode 100644
index 0000000000..d7beca128a
--- /dev/null
+++ b/sysdeps/s390/ifunc-wcsncpy.h
@@ -0,0 +1,53 @@
+/* wcsncpy variant information on S/390 version.
+   Copyright (C) 2018 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 defined USE_MULTIARCH && IS_IN (libc)		\
+  && ! defined HAVE_S390_MIN_Z13_ZARCH_ASM_SUPPORT
+# define HAVE_WCSNCPY_IFUNC	1
+#else
+# define HAVE_WCSNCPY_IFUNC	0
+#endif
+
+#ifdef HAVE_S390_VX_ASM_SUPPORT
+# define HAVE_WCSNCPY_IFUNC_AND_VX_SUPPORT HAVE_WCSNCPY_IFUNC
+#else
+# define HAVE_WCSNCPY_IFUNC_AND_VX_SUPPORT 0
+#endif
+
+#if defined HAVE_S390_MIN_Z13_ZARCH_ASM_SUPPORT
+# define WCSNCPY_DEFAULT	WCSNCPY_Z13
+/* The z13 ifunc variant is using the common code variant as fallback!  */
+# define HAVE_WCSNCPY_C		1
+# define HAVE_WCSNCPY_Z13	1
+#else
+# define WCSNCPY_DEFAULT	WCSNCPY_C
+# define HAVE_WCSNCPY_C		1
+# define HAVE_WCSNCPY_Z13	HAVE_WCSNCPY_IFUNC_AND_VX_SUPPORT
+#endif
+
+#if HAVE_WCSNCPY_C
+# define WCSNCPY_C		__wcsncpy_c
+#else
+# define WCSNCPY_C		NULL
+#endif
+
+#if HAVE_WCSNCPY_Z13
+# define WCSNCPY_Z13		__wcsncpy_vx
+#else
+# define WCSNCPY_Z13		NULL
+#endif
diff --git a/sysdeps/s390/multiarch/Makefile b/sysdeps/s390/multiarch/Makefile
index 7d7b05dcf2..6631fd14d3 100644
--- a/sysdeps/s390/multiarch/Makefile
+++ b/sysdeps/s390/multiarch/Makefile
@@ -1,6 +1,5 @@
 ifeq ($(subdir),wcsmbs)
-sysdep_routines += wcsncpy wcsncpy-vx wcsncpy-c \
-		   wcpncpy wcpncpy-vx wcpncpy-c \
+sysdep_routines += wcpncpy wcpncpy-vx wcpncpy-c \
 		   wcscat wcscat-vx wcscat-c \
 		   wcsncat wcsncat-vx wcsncat-c \
 		   wcscmp wcscmp-vx wcscmp-c \
diff --git a/sysdeps/s390/multiarch/ifunc-impl-list.c b/sysdeps/s390/multiarch/ifunc-impl-list.c
index 656ab59db6..9ebaf4de6f 100644
--- a/sysdeps/s390/multiarch/ifunc-impl-list.c
+++ b/sysdeps/s390/multiarch/ifunc-impl-list.c
@@ -50,6 +50,7 @@
 #include <ifunc-wcsnlen.h>
 #include <ifunc-wcscpy.h>
 #include <ifunc-wcpcpy.h>
+#include <ifunc-wcsncpy.h>
 
 /* Maximum number of IFUNC implementations.  */
 #define MAX_IFUNC	3
@@ -476,6 +477,18 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 		)
 #endif /* HAVE_WCPCPY_IFUNC  */
 
+#if HAVE_WCSNCPY_IFUNC
+    IFUNC_IMPL (i, name, wcsncpy,
+# if HAVE_WCSNCPY_Z13
+		IFUNC_IMPL_ADD (array, i, wcsncpy,
+				dl_hwcap & HWCAP_S390_VX, WCSNCPY_Z13)
+# endif
+# if HAVE_WCSNCPY_C
+		IFUNC_IMPL_ADD (array, i, wcsncpy, 1, WCSNCPY_C)
+# endif
+		)
+#endif /* HAVE_WCSNCPY_IFUNC  */
+
 #ifdef HAVE_S390_VX_ASM_SUPPORT
 
 # define IFUNC_VX_IMPL(FUNC)						\
@@ -484,8 +497,6 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 			      __##FUNC##_vx)				\
 	      IFUNC_IMPL_ADD (array, i, FUNC, 1, __##FUNC##_c))
 
-  IFUNC_VX_IMPL (wcsncpy);
-
   IFUNC_VX_IMPL (wcpncpy);
 
   IFUNC_VX_IMPL (wcscat);
diff --git a/sysdeps/s390/multiarch/wcsncpy-c.c b/sysdeps/s390/wcsncpy-c.c
index 6b89b8c14b..4d0ddb09ec 100644
--- a/sysdeps/s390/multiarch/wcsncpy-c.c
+++ b/sysdeps/s390/wcsncpy-c.c
@@ -16,10 +16,12 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#if defined HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc)
-# define WCSNCPY  __wcsncpy_c
+#include <ifunc-wcsncpy.h>
+
+#if HAVE_WCSNCPY_C
+# if HAVE_WCSNCPY_IFUNC || HAVE_WCSNCPY_Z13
+#  define WCSNCPY WCSNCPY_C
+# endif
 
-# include <wchar.h>
-extern __typeof (__wcsncpy) __wcsncpy_c;
 # include <wcsmbs/wcsncpy.c>
 #endif
diff --git a/sysdeps/s390/multiarch/wcsncpy-vx.S b/sysdeps/s390/wcsncpy-vx.S
index b3400d50d9..9bcbdbf322 100644
--- a/sysdeps/s390/multiarch/wcsncpy-vx.S
+++ b/sysdeps/s390/wcsncpy-vx.S
@@ -16,7 +16,8 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#if defined HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc)
+#include <ifunc-wcsncpy.h>
+#if HAVE_WCSNCPY_Z13
 
 # include "sysdep.h"
 # include "asm-syntax.h"
@@ -40,7 +41,7 @@
    -v18=part of src
    -v31=register save area for r6, r7
 */
-ENTRY(__wcsncpy_vx)
+ENTRY(WCSNCPY_Z13)
 	.machine "z13"
 	.machinemode "zarch_nohighgprs"
 
@@ -217,7 +218,11 @@ ENTRY(__wcsncpy_vx)
 	j	.Llt64
 
 .Lfallback:
-	jg	__wcsncpy_c
-END(__wcsncpy_vx)
-
-#endif /* HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc) */
+	jg	WCSNCPY_C
+END(WCSNCPY_Z13)
+
+# if ! HAVE_WCSNCPY_IFUNC
+strong_alias (WCSNCPY_Z13, __wcsncpy)
+weak_alias (__wcsncpy, wcsncpy)
+# endif
+#endif
diff --git a/sysdeps/s390/multiarch/wcsncpy.c b/sysdeps/s390/wcsncpy.c
index 7209c7d431..e011de7ee7 100644
--- a/sysdeps/s390/multiarch/wcsncpy.c
+++ b/sysdeps/s390/wcsncpy.c
@@ -16,13 +16,24 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#if defined HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc)
+#include <ifunc-wcsncpy.h>
+
+#if HAVE_WCSNCPY_IFUNC
 # include <wchar.h>
 # include <ifunc-resolve.h>
 
-s390_vx_libc_ifunc (__wcsncpy)
-weak_alias (__wcsncpy, wcsncpy)
+# if HAVE_WCSNCPY_C
+extern __typeof (__wcsncpy) WCSNCPY_C attribute_hidden;
+# endif
 
-#else
-# include <wcsmbs/wcsncpy.c>
-#endif /* !(defined HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc)) */
+# if HAVE_WCSNCPY_Z13
+extern __typeof (__wcsncpy) WCSNCPY_Z13 attribute_hidden;
+# endif
+
+s390_libc_ifunc_expr (__wcsncpy, __wcsncpy,
+		      (HAVE_WCSNCPY_Z13 && (hwcap & HWCAP_S390_VX))
+		      ? WCSNCPY_Z13
+		      : WCSNCPY_DEFAULT
+		      )
+weak_alias (__wcsncpy, wcsncpy)
+#endif