S390: Refactor memcmp ifunc handling.

This patch moves all ifunc variants for memcmp
to sysdeps/s390/memcmp-z900.S. The configure-check/preprocessor logic
in sysdeps/s390/ifunc-memcmp.h decides if ifunc is needed at all
and which ifunc variants should be available.
E.g. if the compiler/assembler already supports z196 by default,
the older ifunc variants are not included.
If we only need the newest ifunc variant,
then we can skip ifunc at all.

Therefore the ifunc-resolvers and __libc_ifunc_impl_list are adjusted
in order to handle only the available ifunc variants.

ChangeLog:

	* sysdeps/s390/ifunc-memcmp.h: New File.
	* sysdeps/s390/memcmp.S: Move to ...
	* sysdeps/s390/memcmp-z900.S ... here.
	Move implementations from memcmp-s390x.s to here.
	* sysdeps/s390/multiarch/memcmp-s390x.S: Delete File.
	* sysdeps/s390/multiarch/Makefile (sysdep_routines):
	Remove memcmp variants.
	* sysdeps/s390/Makefile (sysdep_routines):
	Add memcmp variants.
	* sysdeps/s390/multiarch/ifunc-impl-list.c
	(__libc_ifunc_impl_list): Adjust ifunc variants for
	memcmp.
	* sysdeps/s390/multiarch/memcmp.c: Move ifunc resolver
	to ...
	* sysdeps/s390/memcmp.c: ... here.
	Adjust ifunc variants for memcmp.

1 files changed, 59 insertions, 0 deletions

diff --git a/sysdeps/s390/ifunc-memcmp.h b/sysdeps/s390/ifunc-memcmp.h
new file mode 100644
index 0000000000..536ac455d1
--- /dev/null
+++ b/sysdeps/s390/ifunc-memcmp.h
@@ -0,0 +1,59 @@
+/* memcmp 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_Z196_ZARCH_ASM_SUPPORT
+# define HAVE_MEMCMP_IFUNC	1
+#else
+# define HAVE_MEMCMP_IFUNC	0
+#endif
+
+#if defined HAVE_S390_MIN_Z196_ZARCH_ASM_SUPPORT
+# define MEMCMP_DEFAULT		MEMCMP_Z196
+# define HAVE_MEMCMP_Z900_G5	0
+# define HAVE_MEMCMP_Z10	0
+# define HAVE_MEMCMP_Z196	1
+#elif defined HAVE_S390_MIN_Z10_ZARCH_ASM_SUPPORT
+# define MEMCMP_DEFAULT		MEMCMP_Z10
+# define HAVE_MEMCMP_Z900_G5	0
+# define HAVE_MEMCMP_Z10	1
+# define HAVE_MEMCMP_Z196	HAVE_MEMCMP_IFUNC
+#else
+# define MEMCMP_DEFAULT		MEMCMP_Z900_G5
+# define HAVE_MEMCMP_Z900_G5	1
+# define HAVE_MEMCMP_Z10	HAVE_MEMCMP_IFUNC
+# define HAVE_MEMCMP_Z196	HAVE_MEMCMP_IFUNC
+#endif
+
+#if HAVE_MEMCMP_Z900_G5
+# define MEMCMP_Z900_G5		__memcmp_default
+#else
+# define MEMCMP_Z900_G5		NULL
+#endif
+
+#if HAVE_MEMCMP_Z10
+# define MEMCMP_Z10		__memcmp_z10
+#else
+# define MEMCMP_Z10		NULL
+#endif
+
+#if HAVE_MEMCMP_Z196
+# define MEMCMP_Z196		__memcmp_z196
+#else
+# define MEMCMP_Z196		NULL
+#endif