Add _STRING_INLINE_unaligned and string_private.h

As discussed in

https://sourceware.org/ml/libc-alpha/2015-10/msg00403.html

the setting of _STRING_ARCH_unaligned currently controls the external
GLIBC ABI as well as selecting the use of unaligned accesses withing
GLIBC.

Since _STRING_ARCH_unaligned was recently changed for AArch64, this
would potentially break the ABI in GLIBC 2.23, so split the uses and add
_STRING_INLINE_unaligned to select the string ABI. This setting must be
fixed for each target, while _STRING_ARCH_unaligned may be changed from
release to release.  _STRING_ARCH_unaligned is used unconditionally in
glibc.  But <bits/string.h>, which defines _STRING_ARCH_unaligned, isn't
included with -Os.  Since _STRING_ARCH_unaligned is internal to glibc and
may change between glibc releases, it should be made private to glibc.
_STRING_ARCH_unaligned should defined in the new string_private.h heade
file which is included unconditionally from internal <string.h> for glibc
build.

	[BZ #19462]
	* bits/string.h (_STRING_ARCH_unaligned): Renamed to ...
	(_STRING_INLINE_unaligned): This.
	* include/string.h: Include <string_private.h>.
	* string/bits/string2.h: Replace _STRING_ARCH_unaligned with
	_STRING_INLINE_unaligned.
	* sysdeps/aarch64/bits/string.h (_STRING_ARCH_unaligned): Removed.
	(_STRING_INLINE_unaligned): New.
	* sysdeps/aarch64/string_private.h: New file.
	* sysdeps/generic/string_private.h: Likewise.
	* sysdeps/m68k/m680x0/m68020/string_private.h: Likewise.
	* sysdeps/s390/string_private.h: Likewise.
	* sysdeps/x86/string_private.h: Likewise.
	* sysdeps/m68k/m680x0/m68020/bits/string.h
	(_STRING_ARCH_unaligned): Renamed to ...
	(_STRING_INLINE_unaligned): This.
	* sysdeps/s390/bits/string.h (_STRING_ARCH_unaligned): Renamed
	to ...
	(_STRING_INLINE_unaligned): This.
	* sysdeps/sparc/bits/string.h (_STRING_ARCH_unaligned): Renamed
	to ...
	(_STRING_INLINE_unaligned): This.
	* sysdeps/x86/bits/string.h (_STRING_ARCH_unaligned): Renamed
	to ...
	(_STRING_INLINE_unaligned): This.

2 files changed, 22 insertions, 2 deletions

diff --git a/sysdeps/aarch64/bits/string.h b/sysdeps/aarch64/bits/string.h
index 3c2a50ba75..0a508f72c0 100644
--- a/sysdeps/aarch64/bits/string.h
+++ b/sysdeps/aarch64/bits/string.h
@@ -20,5 +20,5 @@
 # error "Never use <bits/string.h> directly; include <string.h> instead."
 #endif
 
-/* AArch64 implementations support efficient unaligned access.  */
-#define _STRING_ARCH_unaligned 1
+/* AArch64 uses the aligned string inline ABI.  */
+#define _STRING_INLINE_unaligned 0
diff --git a/sysdeps/aarch64/string_private.h b/sysdeps/aarch64/string_private.h
new file mode 100644
index 0000000000..8b194a41a6
--- /dev/null
+++ b/sysdeps/aarch64/string_private.h
@@ -0,0 +1,20 @@
+/* Define _STRING_ARCH_unaligned.  AArch64 version.
+   Copyright (C) 2016 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/>.  */
+
+/* AArch64 implementations support efficient unaligned access.  */
+#define _STRING_ARCH_unaligned 1