We have a general principle of preferring optimizations for library
facilities to use compiler built-in functions rather than being
located in library headers, where the compiler can reasonably optimize
code without needing to know glibc implementation details.
This patch applies this principle to bits/byteswap.h, eliminating all
the architecture-specific variants and bits/byteswap-16.h. The
__bswap_16, __bswap_32 and __bswap_64 interfaces all become inline
functions, never macros, using the GCC built-in functions where
available and otherwise a single architecture-independent definition
using shifts and masking (which compilers may well be able to detect
and optimize; GCC has detection of various byte-swapping idioms).
The __bswap_constant_32 macro needs to stay around because of uses in
static initializers within glibc and its tests, and so for consistency
all __bswap_constant_* are kept rather than just being inlined into
the old-GCC-or-non-GCC parts of the __bswap_* inline function
definitions.
Various open bugs are addressed by this cleanup, with caveats about
exactly what is covered by those bugs and when the bugs applied at
all.
Bug 14508 reports -Wformat warnings building glibc because __bswap_*
sometimes returned the wrong types. Obviously we already don't have
such warnings any more or the build would be failing, given -Werror,
and I suspect that bug was originally for wrong types for x86_64, as
fixed by commit d394eb742a (glibc 2.17).
The only case I saw removed by this patch where the types would still
have been wrong was the non-__GNUC__ case of __bswap_64 in the s390
header (using unsigned long long int, but uint64_t would be unsigned
long int for 64-bit). In any case, the single header consistently
uses __uintN_t types after this patch, thereby eliminating all such
bugs. The existing string/test-endian-types.c test already suffices
to verify that the types are correct with the compiler used to build
glibc and its tests.
Bug 15512 reports an error from __bswap_constant_16 with -Werror
-Wsign-conversion. I am unable to reproduce this with any GCC version
supporting -Wsign-conversion - all seem to be able to avoid warning
for ((x) >> 8) & 0xffu, where x is uint16_t, which while it formally
does involve an implicit conversion from int to unsigned int, is also
a case where it should be easy for the compiler to see that the value
converted is never negative. But in this patch __bswap_constant_16 is
changed to use signed 0xff so that no such implicit conversion occurs
at all, and a test with -Werror -Wsign-conversion is added.
Bug 17082 objects to the use of ({}) statement expressions in these
macros preventing use at file scope (in C, that's in sizeof etc.; in
C++, more generally in static initializers). The particular case of
these interfaces is fixed by this patch as it changes them to inline
functions, eliminating all uses of ({}) in bits/byteswap.h, and a
corresponding testcase is added. The bug tries to raise a more
general policy question about use of ({}) in macros in installed
headers, referring to "many other libc functions" (unspecified which
functions are being considered).
Since such policy questions belong on libc-alpha, and since there
*are* macros in installed headers which can't really avoid using ({})
(where they are type-generic, so can't use an inline function, but
need a temporary variable, and a few where the interface involves
returning memory from alloca so can't use an inline function either),
I propose to consider that bug fixed with this change. That is
without prejudice to any other new bugs anyone wishes to file *for
precisely defined sets of macros* requesting moving away from ({})
*where it is clearly possible for those interfaces*. Where ({}) can
be avoided, typically by use of an inline function, I think that's a
good idea - that inline functions are typically to be preferred to
({}) for header interfaces where such optimizations are useful but the
interface is suited to being defined using an inline function.
Bug 20530 requests use of __builtin_bswap16 when available (GCC 4.8
and later), which this patch implements.
Tested for x86_64, and with build-many-glibcs.py. Also did an x86_64
test with the __GNUC_PREREQ conditionals changed to "#if 0" to verify
the old-GCC/non-GCC case in the headers. (There are already existing
tests for correctness of results of these interfaces.)
[BZ #14508]
[BZ #15512]
[BZ #17082]
[BZ #20530]
* bits/byteswap.h: Update file comment. Do not include
<bits/byteswap-16.h>.
(__bswap_constant_16): Cast result to __uint16_t. Use signed 0xff
constant.
(__bswap_16): Define as inline function.
(__bswap_constant_32): Reformat definition.
(__bswap_32): Always define as inline function, not macro, using
__uint32_t. Use __builtin_bswap32 if [__GNUC_PREREQ (4, 3)],
otherwise __bswap_constant_32.
(__bswap_constant_64): Reformat definition. Do not use
__extension__ here.
(__bswap_64): Always define as inline function, not macro. Use
__extension__ on function definition. Use __builtin_bswap64 if
[__GNUC_PREREQ (4, 3)], otherwise __bswap_constant_64.
* string/test-endian-file-scope.c: New file.
* string/test-endian-sign-conversion.c: Likewise.
* string/Makefile (headers): Remove bits/byteswap-16.h.
(tests): Add test-endian-file-scope and
test-endian-sign-conversion.
(CFLAGS-test-endian-sign-conversion.c): New variable.
* bits/byteswap-16.h: Remove file.
* sysdeps/ia64/bits/byteswap-16.h: Likewise.
* sysdeps/ia64/bits/byteswap.h: Likewise.
* sysdeps/m68k/bits/byteswap.h: Likewise.
* sysdeps/s390/bits/byteswap-16.h: Likewise.
* sysdeps/s390/bits/byteswap.h: Likewise.
* sysdeps/tile/bits/byteswap.h: Likewise.
* sysdeps/x86/bits/byteswap-16.h: Likewise.
* sysdeps/x86/bits/byteswap.h: Likewise.
The __builtin_bswap* functions were introduced in gcc-4.3, not gcc-4.2.
Fix the __GNUC_PREREQ tests to reflect this.
Otherwise trying to compile code with gcc-4.2 falls down:
In file included from /usr/include/endian.h:60,
from /usr/include/ctype.h:40,
/usr/include/bits/byteswap.h: In function 'unsigned int __bswap_32(unsigned int)':
/usr/include/bits/byteswap.h:46: error: '__builtin_bswap32' was not declared in this scope
/usr/include/bits/byteswap.h: In function 'long long unsigned int __bswap_64(long long unsigned int)':
/usr/include/bits/byteswap.h:110: error: '__builtin_bswap64' was not declared in this scope
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
[BZ#13926]
Currently __bswap_64 is not defined at all for non-GCC compilers.
Define it but guard it with __GLIBC_HAVE_LONG_LONG.
endian.h uses __bswap_64, make the functions only available
if __GLIBC_HAVE_LONG_LONG is defined.
2001-07-06 Paul Eggert <eggert@twinsun.com>
* manual/argp.texi: Remove ignored LGPL copyright notice; it's
not appropriate for documentation anyway.
* manual/libc-texinfo.sh: "Library General Public License" ->
"Lesser General Public License".
2001-07-06 Andreas Jaeger <aj@suse.de>
* All files under GPL/LGPL version 2: Place under LGPL version
2.1.
2000-12-26 Ulrich Drepper <drepper@redhat.com>
* sysdeps/generic/bits/byteswap.h (__bswap_64): Make it usable for
64bit platforms. Reported by Dave Gilbert <gilbertd@treblig.org>.
1998-11-20 Ulrich Drepper <drepper@cygnus.com>
* aclocal.m4 (LIBC_PROG_BINUTILS): Also add AR and RANLIB using the
same method.
* configure.in: Don't define AR and RANLIB here.
* inet/gethstbyad_r.c: Define NEED__RES_HCONV and POSTPROCESS for
host name res_hconf code.
* inet/gethstbynm_r.c: Likewise.
* nss/getXXbyYY_r.c: Include resolv/res_hconf.h if NEED__RES_HCONF
is defined. Call res_hconf_init if necessary. If POSTPROCESS is
defined execute the code.
* resolv/Makefile (routines): Add res_hconf.
(headers): Add res_hconf.h.
* resolv/res_hconf.c: Pretty print.
* resolv/res_hconf.h: Likewise.
1998-11-20 Ulrich Drepper <drepper@cygnus.com>
* sysdeps/generic/bits/byteswap.h: Fix typos in non-GCC
definitions. Reported by Scott Bambrough <scottb@corelcomputer.com>.
1998-11-20 1998 Andreas Schwab <schwab@issan.cs.uni-dortmund.de>
* math/libm-test.c: Raise some epsilons a bit.
1998-11-20 Andreas Schwab <schwab@issan.cs.uni-dortmund.de>
* Makeconfig ($(common-objpfx)sysd-sorted): Fix portability problems.
1998-11-20 Ulrich Drepper <drepper@cygnus.com>
* Makefile (distribute): Add scripts/gen-sorted.awk.
1998-07-31 17:59 Ulrich Drepper <drepper@cygnus.com>
* sysdeps/generic/bits/byteswap.h: Fix problems with side effects.
* manual/filesys.texi: Document truncate and ftruncate.
Patch by Michael Deutschmann <michael@talamasca.wkpowerlink.com>.
* shadow/putspent.c: Lock stream while generating the output.
* sunrpc/clnt_unix.c: Use ucred instead of cmsgcred again.
(__msgwrite): Rewrite accordingly.
* sunrpc/svc_unix.c: Likewise.
* sysdeps/unix/sysv/linux/Dist: Remove __recvmsg.S and __sendmsg.S.
* sysdeps/unix/sysv/linux/Makefile [$(subdir)==socket]
(sysdep_routines): Remove __sendmsg and __recvmsg.
* sysdeps/unix/sysv/linux/__recvmsg.S: Removed.
* sysdeps/unix/sysv/linux/__sendmsg.S: Removed.
* sysdeps/unix/sysv/linux/recvmsg.c: Removed.
* sysdeps/unix/sysv/linux/sendmsg.c: Removed.
* sysdeps/unix/sysv/linux/recvmsg.S: New file.
* sysdeps/unix/sysv/linux/sendmsg.S: New file.
* sysdeps/unix/sysv/linux/bits/socket.h: Define SCM_CREDENTIALS and
struct ucred. Remove struct cmsgcred.
Patches by Thorsten Kukuk.
1998-08-03 Andreas Jaeger <aj@arthur.rhein-neckar.de>
* inet/rcmd.c (__ivaliduser): Allow '#' as comment character.
1998-08-08 14:42 Ulrich Drepper <drepper@cygnus.com>
* argp/argp-help.c: Prepare to be used outside glibc without gcc by
adding usual alloca cruft.
Reported by Eleftherios Gkioulekas <lf@amath.washington.edu>.
1998-04-05 Jim Meyering <meyering@ascend.com>
* lib/regex.c (WIDE_CHAR_SUPPORT): Define.
This now depends on HAVE_BTOWC so systems that lack btowc (like
solaris-2.5.1) don't lose.
1998-08-07 Mark Kettenis <kettenis@phys.uva.nl>
* sysdeps/generic/bits/sigaction.h: Remove definition of SA_DISABLE.
* sysdeps/generic/bits/sigstack.h: Define SS_DISABLE, SS_ONSTACK,
MINSIGSTKZ and SIGSTKSZ. Definitions match BSD.
* hurd/sigunwind.c (_hurdsig_longjmp_from_handler): Use SS_ONSTACK
instead of SA_ONSTACK.
* sysdeps/mach/hurd/sigaltstack.c (__sigaltstack): Renamed from
sigaltstack, and created a weak alias. Use SS_DISABLE and
SS_ONSTACK instead of SA_DISABLE and SA_ONSTACK.
* sysdeps/mach/hurd/sigstack.c (sigstack): Use SS_ONSTACK instead
of SA_ONSTACK. Call __sigaltstack instead of sigaltstack.
* sysdeps/mach/hurd/i386/sigreturn.c (__sigreturn): Use SS_ONSTACK
instead of SA_ONSTACK.
* sysdeps/mach/hurd/alpha/sigreturn.c (__sigreturn): Likewise.
* sysdeps/mach/hurd/mips/sigreturn.c (__sigreturn): Likewise.
* sysdeps/mach/hurd/i386/trampoline.c (_hurd_setup_sighandler):
Use SS_DISABLE instead of SA_DISABLE. Use SS_ONSTACK instead of
SA_ONSTACK where appropriate.
* sysdeps/mach/hurd/alpha/trampoline.c (_hurd_setup_sighandler):
Likewise.
* sysdeps/mach/hurd/hppa/trampoline.c (_hurd_setup_sighandler):
Likewise.
* sysdeps/mach/hurd/mips/trampoline.c (_hurd_setup_sighandler):
Likewise.
* manual/signal.texi (Signal Stack): Talk about SS_DISABLE and
SS_ONSTACK instead of SA_DISABLE and SA_ONSTACK in discussion of
the `ss_flags' member of `struct sigaltstack'.
1998-08-05 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* libio/Makefile (routines) [$(versioning)=yes]: Add oldtmpfile.
(shared-only-routines): Likewise.
* libio/oldtmpfile.c: New file
* stdio-common/tmpfile.c: Use __fdopen and __close.
[USE_IN_LIBIO]: Use _IO_fdopen instead of _IO_new_fdopen. Put
tmpfile on symbol version GLIBC_2.1.
* stdio-common/tmpfile64.c: Use __fdopen and __close.
[USE_IN_LIBIO]: Use _IO_fdopen instead of _IO_new_fdopen.
* stdio-common/Version [GLIBC_2.1]: Add tmpfile.
* stdio-common/tempnam.c: Use __strdup instead of strdup.
* sysdeps/posix/fdopen.c: Define __fdopen and make fdopen weak
alias.
* sysdeps/generic/fdopen.c: Likewise.
* sysdeps/mach/hurd/fdopen.c: Likewise.
* stdio/stdio.h: Declare __fdopen.
* sunrpc/openchild.c: Use __fdopen instead of fdopen.
[USE_IN_LIBIO]: Map __fdopen to _IO_fdopen.
* sysdeps/posix/tempname.c (__gen_tempname): Don't bother checking
__stub_open64, it is never defined.
1998-08-05 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* libio/iofopen64.c: Fix typo. Avoid unnessary casts.
* libio/iopopen.c: Unlink file before freeing it if command
creation failed. Avoid unnessary casts.
* libio/iofdopen.c: Avoid unnecessary cast.
* pwd/fgetpwent_r.c [USE_IN_LIBIO]: Map funlockfile to
_IO_funlockfile.
* pwd/fgetspent_r.c [USE_IN_LIBIO]: Likewise.
1998-08-06 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* grp/grp.h, pwd/pwd.h: Don't declare __grpopen, __grpread,
__grpalloc, __grpscan and the corresponding pwd functions, they
were removed long ago.
1998-08-06 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* math/libm-test.c (csqrt_test): Adjust epsilons.
(casinh_test): Likewise.
1998-08-06 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* posix/globtest.sh: Fix typo. Remove second test output file.
1998-08-07 Cristian Gafton <gafton@redhat.com>
* pwd/putpwent.c (putpwent): Avoid writting (none) in the passwd file.
* shadow/putspent.c (putspent): Likewise.
* grp/putgrent.c: New file.
* grp/Makefile (routines): Add putgrent.
* grp/Versions [GLIBC_2.1]: Add putgrent.
* grp/grp.h: Add putgrent prototype.
1998-08-04 19:33 Ulrich Drepper <drepper@cygnus.com>
* elf/elf.h: More ELF definitions.
