It’s not necessary and provides no thread safety guarantees.
The `volatile` qualifiers on the function arguments have to be kept, as
they are (unfortunately) part of the API.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #600
__atomic_load_8 and friends do not exist under clang. Use the generic
__atomic_load variant instead that are documented here:
https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html
These have the additional benefit that the exact size of gint (4 bytes)
or gpointer (4 or 8 bytes) no longer have to be checked.
I initially tried `__typeof__(*(atomic)) val;`, but that caused warnings
in Clang (-Wincompatible-pointer-types-discards-qualifiers) when
"atomic" points to a volatile variable. Aside from that, it is
apparently not supported everywhere, see the g_has_typeof macro.
Another reason not to use it are new warnings under Clang, including:
glib/deprecated/gthread-deprecated.c:683:11: warning: incompatible pointer types initializing 'typeof (*(&mutex->mutex.mutex))' (aka 'union _GMutex *') with an expression of type 'GRecMutex *' (aka 'struct _GRecMutex *') [-Wincompatible-pointer-types]
g_atomic_pointer_set (&mutex->mutex.mutex, result);
Hence, cast the atomic variable to gint/gpointer pointers, the size was
already statically asserted so the cast should be safe.
The macros use a (hopefully) rare "gaps_temp" name instead of something
like "val" to avoid an issue with GCC builds:
glib/tests/once.c:123:test_once4: assertion failed (val == "foo"): (NULL == "foo")
Closes#1843
All glib/*.{c,h} files have been processed, as well as gtester-report.
12 of those files are not licensed under LGPL:
gbsearcharray.h
gconstructor.h
glibintl.h
gmirroringtable.h
gscripttable.h
gtranslit-data.h
gunibreak.h
gunichartables.h
gunicomp.h
gunidecomp.h
valgrind.h
win_iconv.c
Some of them are generated files, some are licensed under a BSD-style
license and win_iconv.c is in the public domain.
Sub-directories inside glib/:
deprecated/: processed in a previous commit
glib-mirroring-tab/: already LGPLv2.1+
gnulib/: not modified, the code is copied from gnulib
libcharset/: a copy
pcre/: a copy
tests/: processed in a previous commit
https://bugzilla.gnome.org/show_bug.cgi?id=776504
This code assumes that int is exactly 32 bits, and that pointers
are either 4 or 8 bits, on platforms with __ATOMIC_SEQ_CST.
In practice this is going to be true.
A previous attempt at this assertion placed the G_STATIC_ASSERT
at the top level in gatomic.h, but that broke anjuta, which
redefined __unused__ at the time. These assertions are about the
platform/compiler ABI, so it's sufficient to check them once,
while compiling GLib itself; accordingly, move them to the
implementation.
Bug: https://bugzilla.gnome.org/show_bug.cgi?id=730932
Add various (nullable) and (optional) annotations which were missing
from a variety of functions. Also port a couple of existing (allow-none)
annotations in the same files to use (nullable) and (optional) as
appropriate instead.
Secondly, add various (not nullable) annotations as needed by the new
default in gobject-introspection of marking gpointers as (nullable). See
https://bugzilla.gnome.org/show_bug.cgi?id=729660.
This includes adding some stub documentation comments for the
assertion macro error functions, which weren’t previously documented.
The new comments are purely to allow for annotations, and hence are
marked as (skip) to prevent the symbols appearing in the GIR file.
https://bugzilla.gnome.org/show_bug.cgi?id=719966
I added these because the older mingw32 toolchain didn't have
MemoryBarrier(). The newer mingw-w64 toolchain however has.
As reported by John Emmas this was causing build failure with
MSVC because of inline issues. But that reminded me that we
may be taking this path even if the system implements
MemoryBarrier as a function, which is a waste. So, just remove
it.
We clean up the detection of if we should do 'real' atomic operations or
mutex-emulated ones with the introduction of a new (public) macro:
G_ATOMIC_LOCK_FREE. If defined, our atomic operations are guaranteed to
be done in hardware.
We need to use __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4 to determine if our
compiler supports GCC-style atomic operations from the gatomic.h header
because we might be building a program against GLib using a different
set of compiler options (or a different compiler) than was used to build
GLib itself.
Unfortunately, this macro is not available on clang, so it has currently
regressed to using the mutex emulation. A bug about that has been
opened here:
http://llvm.org/bugs/show_bug.cgi?id=11174
GStaticMutex makes use of atomic operations to initialise itself. We
were using GStaticMutex from the emulated case of gatomic. Use pthreads
directly to avoid unbounded recursion in this case.
- remove all inline assembly versions
- implement the atomic operations using either GCC intrinsics, the
Windows interlocked API or a mutex-based fallback
- drop gatomic-gcc.c since these are now defined in the header file.
Adjust Makefile.am accordingly.
- expand the set of operations: support 'get', 'set', 'compare and
exchange', 'add', 'or', and 'xor' for both integers and pointers
- deprecate g_atomic_int_exchange_and_add since g_atomic_int_add (as
with all the new arithmetic operations) now returns the prior value
- unify the use of macros: all functions are now wrapped in macros that
perform the proper casts and checks
- remove G_GNUC_MAY_ALIAS use; it was never required for the integer
operations (since casting between pointers that only vary in
signedness of the target is explicitly permitted) and we avoid the
need for the pointer operations by using simple 'void *' instead of
'gpointer *' (which caused the 'type-punned pointer' warning)
- provide function implementations of g_atomic_int_inc and
g_atomic_int_dec_and_test: these were strictly macros before
- improve the documentation to make it very clear exactly which types
of pointers these operations may be used with
- remove a few uses of the now-deprecated g_atomic_int_exchange_and_add
- drop initialisation of gatomic from gthread (by using a GStaticMutex
instead of a GMutex)
- update glib.symbols and documentation sections files
Closes#650823 and #650935
GLib users buildable with gcc 4.4. Patch by Jakub Jelinek.
* glib/gatomic.[hc]: Add G_GNUC_MAY_ALIAS to pointer arguments,
fix macro versions to only operate on objects of the same size.
* glib/gdataset.c:
* glib/gthread.[hc]:
* glib/gdatasetprivate.h: Remove unnecessary casts in
g_atomic_pointer_get calls.
svn path=/trunk/; revision=7875
2007-11-18 Matthias Clasen <mclasen@redhat.com>
* configure.in: Check whether assembler supports numerical local
labels.
* glib/gatomic.c: Fix powerpc implementation of atomic ops for
platforms where the assembler doesn't support numerical local
labels. (#445362)
svn path=/trunk/; revision=5861
2006-05-09 Sebastian Wilhelmi <wilhelmi@google.com>
* glib/gthreadinit.h: Renamed to glib/gthreadprivate.h and moved
system thread identifier comparision and assignment macros from
glib/gthread.c to glib/gthreadprivate.h.
* glib/Makefile.am, glib/gatomic.c, glib/gconvert.c, glib/gmain.c,
glib/gmem.c, glib/gmessages.c, glib/grand.c, glib/gslice.c,
glib/gthread.c, glib/gutils.c, gthread/gthread-impl.c: Use
glib/gthreadprivate.h instead of glib/gthreadinit.h.
* gthread/gthread-impl.c: Use GSystemThread instead of GThread for
owner determination. This fixes#311043 and is mostly modeled
after the patch from jylefort@FreeBSD.org.
2006-04-19 Tor Lillqvist <tml@novell.com>
* glib/gatomic.c: Adapt to the changed prototype of
InterlockedCompareExchange() in newer SDKs. Use
InterlockedCompareExchangePointer() when applicable. (#155884,
John Ehresman)
2005-12-17 Sebastian Wilhelmi <seppi@seppi.de>
* glib/gatomic.c: Fix memory barrier position in g_atomic_int_get
and g_atomic_pointer_get. Add g_atomic_int_set and
g_atomic_pointer_set implementations for the !DEFINE_WITH_MUTEXES &&
G_ATOMIC_OP_MEMORY_BARRIER_NEEDED case, as well as defining them
as functions (additionally to the macros in the header) for the
!G_ATOMIC_OP_MEMORY_BARRIER_NEEDED case.
Tue Dec 13 10:13:32 2005 Tim Janik <timj@imendio.com>
* glib/gatomic.h: added g_atomic_pointer_set() and g_atomic_int_set()
for systems where the initialization of atomic variables requires a
write memory barrier.
2005-12-05 Matthias Clasen <mclasen@redhat.com>
* tests/libmoduletestplugin_a.c: Fix compiler warnings.
* glib/gatomic.c: In the ia64 implementation, use
__sync builtin without _si or _di suffix. (#321229,
Stanislav Brabec, patch by Andreas Schwab)
2005-08-04 Matthias Clasen <mclasen@redhat.com>
* glib/glib.symbols:
* glib/gatomic.[hc]: Always export g_atomic_int_get and
g_atomic_pointer_get as functions, even if we have macros,
to avoid changing the ABI depending on configuration.
* glib/gatomic.c: Fix the s390 implementations of
g_atomic_pointer_compare_and_exchange.
2005-03-13 Matthias Clasen <mclasen@redhat.com>
Make PLT-reduction work with gcc4, and don't include
everything in galias.h:
* glib/glib.symbols: Group symbols by header and source file.
* glib/makegalias.pl: Protect definitions by the same
preprocessor symbols used to guard the headers. Move
the alias declarations to a separate file which is
produced when calling makegalias.pl -def
* glib/Makefile.am (galiasdef.c): Add a rule to generate this
file.
* glib/*.c: Include galias.h after the other GLib headers,
include galiasdef.c at the bottom.
Sun Feb 6 12:09:55 2005 Manish Singh <yosh@gimp.org>
* glib/gatomic.c: Don't use matching constraints for asm mem
parameters. This makes the code match with current glibc, and
quiets some warnings with gcc 3.4.
