S390: Refactor memrchr ifunc handling.

The ifunc handling for memrchr is adjusted in order to omit ifunc
variants if those will never be used as the minimum architecture level
already supports newer CPUs by default.

ChangeLog:

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

7 files changed, 102 insertions, 21 deletions

diff --git a/sysdeps/s390/Makefile b/sysdeps/s390/Makefile
index 649f29a..0e86242 100644
--- a/sysdeps/s390/Makefile
+++ b/sysdeps/s390/Makefile
@@ -78,5 +78,6 @@ sysdep_routines += bzero memset memset-z900 \
 		   strcspn strcspn-vx strcspn-c \
 		   memchr memchr-vx memchr-z900 \
 		   rawmemchr rawmemchr-vx rawmemchr-c \
-		   memccpy memccpy-vx memccpy-c
+		   memccpy memccpy-vx memccpy-c \
+		   memrchr memrchr-vx memrchr-c
 endif
diff --git a/sysdeps/s390/ifunc-memrchr.h b/sysdeps/s390/ifunc-memrchr.h
new file mode 100644
index 0000000..9d80d55
--- /dev/null
+++ b/sysdeps/s390/ifunc-memrchr.h
@@ -0,0 +1,52 @@
+/* memrchr 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_MEMRCHR_IFUNC	1
+#else
+# define HAVE_MEMRCHR_IFUNC	0
+#endif
+
+#ifdef HAVE_S390_VX_ASM_SUPPORT
+# define HAVE_MEMRCHR_IFUNC_AND_VX_SUPPORT HAVE_MEMRCHR_IFUNC
+#else
+# define HAVE_MEMRCHR_IFUNC_AND_VX_SUPPORT 0
+#endif
+
+#if defined HAVE_S390_MIN_Z13_ZARCH_ASM_SUPPORT
+# define MEMRCHR_DEFAULT	MEMRCHR_Z13
+# define HAVE_MEMRCHR_C		0
+# define HAVE_MEMRCHR_Z13	1
+#else
+# define MEMRCHR_DEFAULT	MEMRCHR_C
+# define HAVE_MEMRCHR_C		1
+# define HAVE_MEMRCHR_Z13	HAVE_MEMRCHR_IFUNC_AND_VX_SUPPORT
+#endif
+
+#if HAVE_MEMRCHR_C
+# define MEMRCHR_C		__memrchr_c
+#else
+# define MEMRCHR_C		NULL
+#endif
+
+#if HAVE_MEMRCHR_Z13
+# define MEMRCHR_Z13		__memrchr_vx
+#else
+# define MEMRCHR_Z13		NULL
+#endif
diff --git a/sysdeps/s390/multiarch/memrchr-c.c b/sysdeps/s390/memrchr-c.c
index 1e3c914..333c0fc 100644
--- a/sysdeps/s390/multiarch/memrchr-c.c
+++ b/sysdeps/s390/memrchr-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 MEMRCHR  __memrchr_c
+#include <ifunc-memrchr.h>
+
+#if HAVE_MEMRCHR_C
+# if HAVE_MEMRCHR_IFUNC
+#  define MEMRCHR MEMRCHR_C
+# endif
 
-# include <string.h>
-extern __typeof (__memrchr) __memrchr_c;
 # include <string/memrchr.c>
 #endif
diff --git a/sysdeps/s390/multiarch/memrchr-vx.S b/sysdeps/s390/memrchr-vx.S
index 8e81f5e..ba832f1 100644
--- a/sysdeps/s390/multiarch/memrchr-vx.S
+++ b/sysdeps/s390/memrchr-vx.S
@@ -16,7 +16,9 @@
    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-memrchr.h>
+
+#if HAVE_MEMRCHR_Z13
 
 # include "sysdep.h"
 # include "asm-syntax.h"
@@ -40,7 +42,7 @@
    -v18=c replicated
    -v20=permute pattern
 */
-ENTRY(__memrchr_vx)
+ENTRY(MEMRCHR_Z13)
 	.machine "z13"
 	.machinemode "zarch_nohighgprs"
 
@@ -156,5 +158,11 @@ ENTRY(__memrchr_vx)
 
 	clgijhe	%r4,64,.Lloop64	/* If n >= 64 -> loop64.  */
 	j	.Llt64
-END(__memrchr_vx)
-#endif /* HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc) */
+END(MEMRCHR_Z13)
+
+# if ! HAVE_MEMRCHR_IFUNC
+strong_alias (MEMRCHR_Z13, __memrchr)
+weak_alias (__memrchr, memrchr)
+# endif
+
+#endif /* HAVE_MEMRCHR_Z13  */
diff --git a/sysdeps/s390/multiarch/memrchr.c b/sysdeps/s390/memrchr.c
index 43a44ab..d995e99 100644
--- a/sysdeps/s390/multiarch/memrchr.c
+++ b/sysdeps/s390/memrchr.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-memrchr.h>
+
+#if HAVE_MEMRCHR_IFUNC
 # include <string.h>
 # include <ifunc-resolve.h>
 
-s390_vx_libc_ifunc (__memrchr)
-weak_alias (__memrchr, memrchr)
+# if HAVE_MEMRCHR_C
+extern __typeof (__memrchr) MEMRCHR_C attribute_hidden;
+# endif
 
-#else
-# include <string/memrchr.c>
-#endif /* !(defined HAVE_S390_VX_ASM_SUPPORT && IS_IN (libc)) */
+# if HAVE_MEMRCHR_Z13
+extern __typeof (__memrchr) MEMRCHR_Z13 attribute_hidden;
+# endif
+
+s390_libc_ifunc_expr (__memrchr, __memrchr,
+		      (HAVE_MEMRCHR_Z13 && (hwcap & HWCAP_S390_VX))
+		      ? MEMRCHR_Z13
+		      : MEMRCHR_DEFAULT
+		      )
+weak_alias (__memrchr, memrchr)
+#endif /* HAVE_MEMRCHR_IFUNC  */
diff --git a/sysdeps/s390/multiarch/Makefile b/sysdeps/s390/multiarch/Makefile
index d5a32fc..260b514 100644
--- a/sysdeps/s390/multiarch/Makefile
+++ b/sysdeps/s390/multiarch/Makefile
@@ -1,7 +1,3 @@
-ifeq ($(subdir),string)
-sysdep_routines += memrchr memrchr-vx memrchr-c
-endif
-
 ifeq ($(subdir),wcsmbs)
 sysdep_routines += wcslen wcslen-vx wcslen-c \
 		   wcsnlen wcsnlen-vx wcsnlen-c \
diff --git a/sysdeps/s390/multiarch/ifunc-impl-list.c b/sysdeps/s390/multiarch/ifunc-impl-list.c
index b891774..0f01b99 100644
--- a/sysdeps/s390/multiarch/ifunc-impl-list.c
+++ b/sysdeps/s390/multiarch/ifunc-impl-list.c
@@ -45,6 +45,7 @@
 #include <ifunc-memchr.h>
 #include <ifunc-rawmemchr.h>
 #include <ifunc-memccpy.h>
+#include <ifunc-memrchr.h>
 
 /* Maximum number of IFUNC implementations.  */
 #define MAX_IFUNC	3
@@ -411,6 +412,18 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 		)
 #endif /* HAVE_MEMCCPY_IFUNC  */
 
+#if HAVE_MEMRCHR_IFUNC
+    IFUNC_IMPL (i, name, memrchr,
+# if HAVE_MEMRCHR_Z13
+		IFUNC_IMPL_ADD (array, i, memrchr,
+				dl_hwcap & HWCAP_S390_VX, MEMRCHR_Z13)
+# endif
+# if HAVE_MEMRCHR_C
+		IFUNC_IMPL_ADD (array, i, memrchr, 1, MEMRCHR_C)
+# endif
+		)
+#endif /* HAVE_MEMRCHR_IFUNC  */
+
 #ifdef HAVE_S390_VX_ASM_SUPPORT
 
 # define IFUNC_VX_IMPL(FUNC)						\
@@ -457,8 +470,6 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 
   IFUNC_VX_IMPL (wmemcmp);
 
-  IFUNC_VX_IMPL (memrchr);
-
 #endif /* HAVE_S390_VX_ASM_SUPPORT */
 
   return i;