This was originally added so that you could replace a T with
QAtomicInteger<T> in the same class and still keep ABI. However, for
legacy reasons, on 32-bit x86, types larger than 4 bytes keep an old
1990s alignment of only 4 bytes, but modern std::atomic<T> for those 8-
byte types enforces an alignment of 8 bytes. Therefore, the requirement
to keep alignment is not possible to guarantee.
In other words: you may not replace T with QAtomicInteger<T> or
std::atomic<T> and assume no ABI breakages in all platforms.
This is a requirement to implement atomicity. An 8-byte type aligned to
only a 4-byte boundary could cross a 16-byte boundary or, worse, cross a
cacheline boundary. Crossing the 16-byte boundary could be bad on some
processors, but crossing the cacheline boundary (addresses ending in
0x3C, 0x7C, 0xCC and 0xFC, or 4 out of 64 possible addresses or 6.25%)
is always bad: the CPUs cannot guarantee an atomic load or store
operation.
See also <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71660>.
Task-number: QTBUG-67858
Change-Id: If90a92b041d3442fa0a4fffd15283e4615474582
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@qt.io>
Drop addSub() test. It executes exactly the union of fetchAndAdd()
and fetchAndSub(), which have already had their UBs fixed.
No need to do fixes in duplicated code.
Change-Id: Ib72caab0310fce3ff9a40c261d8a38518f91ecaf
Reviewed-by: David Faure <david.faure@kdab.com>
This change partially reverts 1bfc7f68 about QT_HAS_BUILTIN define
and undef in src/corelib/tools/qsimd_p.h.
This change is also squashed with "Fall back to c++11 standard
compiler flag for host builds" which is done by Peter Seiderer.
Conflicts:
mkspecs/features/default_post.prf
src/3rdparty/sqlite/0001-Fixing-the-SQLite3-build-for-WEC2013-again.patch
src/3rdparty/sqlite/sqlite3.c
src/corelib/tools/qsimd_p.h
src/gui/kernel/qevent.cpp
src/gui/kernel/qwindowsysteminterface.cpp
src/gui/kernel/qwindowsysteminterface_p.h
src/plugins/bearer/blackberry/blackberry.pro
src/plugins/platforms/cocoa/qcocoasystemsettings.mm
src/plugins/platformthemes/gtk2/gtk2.pro
src/plugins/styles/bb10style/bb10style.pro
src/sql/drivers/sqlite2/qsql_sqlite2.cpp
tools/configure/configureapp.cpp
Task-number: QTBUG-51644
Done-with: Peter Seiderer <ps.report@gmx.net>
Change-Id: I6100d6ace31b2e8d41a95f0b5d5ebf8f1fd88b44
Signed integer overflows and underflows are undefined
behavior. A test that invokes UB tests nothing, because
the standard permits any outcome.
Fix by guarding the respective operations so
they are not executed if they would overflow
or underflow.
Change-Id: I40354ee88f40e4b47b70eac7790dc3a79ac70a57
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Not that we require it, but since The Qt Company did it for all files
they have copyright, even if they haven't touched the file in years
(especially not in 2016), I'm doing the same.
Change-Id: I7a9e11d7b64a4cc78e24ffff142b4c9d53039846
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>
From Qt 5.7 -> tools & applications are lisenced under GPL v3 with some
exceptions, see
http://blog.qt.io/blog/2016/01/13/new-agreement-with-the-kde-free-qt-foundation/
Updated license headers to use new GPL-EXCEPT header instead of LGPL21 one
(in those files which will be under GPL 3 with exceptions)
Change-Id: I42a473ddc97101492a60b9287d90979d9eb35ae1
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>
[ChangeLog][Important Behavior Changes] Starting with Qt 5.7, Qt
requires a C++11 compiler with support for C++11 atomics. This affects
user code too: Qt headers no longer compile with a C++98 compiler. The
minimum compiler versions for this release are:
* Clang 3.4 (found in XCode 5.1)
* GCC 4.7
* Microsoft Visual Studio 2012
Change-Id: Ib056b47dde3341ef9a52ffff13ef1f496ea9363f
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Dmitry Shachnev <mitya57@gmail.com>
The keyword no longer has a meaning for the new CI.
Change-Id: Ibcea4c7a82fb7f982cf4569fdff19f82066543d1
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>
And add tests for the GCC intrinsics and for std::atomic.
Task-number: QTBUG-43794
Change-Id: Ic5d393bfd36e48a193fcffff13b9b2dbaee80469
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Qt copyrights are now in The Qt Company, so we could update the source
code headers accordingly. In the same go we should also fix the links to
point to qt.io.
Outdated header.LGPL removed (use header.LGPL21 instead)
Old header.LGPL3 renamed to header.LGPL3-COMM to match actual licensing
combination. New header.LGPL-COMM taken in the use file which were
using old header.LGPL3 (src/plugins/platforms/android/extract.cpp)
Added new header.LGPL3 containing Commercial + LGPLv3 + GPLv2 license
combination
Change-Id: I6f49b819a8a20cc4f88b794a8f6726d975e8ffbe
Reviewed-by: Matti Paaso <matti.paaso@theqtcompany.com>
Change-Id: I91ff06644e8047c2ca483f9768b46c1372eb6171
Reviewed-by: Martin Smith <martin.smith@digia.com>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@theqtcompany.com>
MSVC 2008 is confused by TypeInStruct being a template, resulting in
\tst_qatomicinteger.cpp(189) : error C2027: use of undefined type 'QStaticAssertFailure<Test>'
with
[
Test=false
]
for int (and thus for all unsupported types). This appears to be a real
Heisenbug-nature compiler bug as it can also be fixed by adding
qDebug() << Q_ALIGNOF(TypeInStruct<T>)
before the static assert.
Task-number: QTBUG-37195
Change-Id: Ib2b60f3c1ffeb0b8bdeb1fb0c659655ce4ab10d8
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This is extremely useful, since the most common action after a failed
compare-and-swap is to loop around, trying again with the current
value as found in memory.
Code currently written as:
do {
Type value = atomic.load();
...
} while (!atomic.testAndSetRelaxed(value, desired));
Becomes:
Type value = atomic.load();
do {
...
} while (!atomic.testAndSetRelaxed(value, desired, value));
In most CPU architectures, the value that was found in memory is known
to the compare-and-swap code, so this is more efficient than the
previous code. In architectures where the value is not known, the new
code is no worse than before.
The implementation sometimes modified an existing function, sometimes
it added a new one, depending on whether more registers were needed in
the assembly (like ARMv6-7), the code became more complex (ARMv5), the
optimizer failed (C++11), or it was just plain equivalent (MIPS).
Change-Id: I7d6d200ea9746ec8978a0c1e1969dbc3580b9285
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This simplifies the code a lot and avoids silly mistakes where a
specific integer type is missing (such as char16_t).
Change-Id: Id91dfd1919e783e0a9af7bfa093ca560a01b22d1
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
