-
Bug
-
Resolution: Unresolved
-
P4: Low
-
6.9.2
-
None
-
Linux/X11
As already described in QTBUG-56264 for Qt 5.x, the following simple program crashes on sparc64:
#include <QtGui/QGuiApplication> #include <QtQml/QJSEngine> int main(int argc, char **argv) { QGuiApplication app(argc, argv); QJSEngine engine; return 0; }
Full backtrace:
(gdb) bt #0 QV4::StaticValue::m (this=0x0, this=<optimized out>) at ./src/qml/common/qv4staticvalue_p.h:572 #1 QV4::InternalClass::d_unchecked (this=0x0, this=<optimized out>) at ./src/qml/jsruntime/qv4managed_p.h:189 #2 QV4::InternalClass::d (this=0x0, this=<optimized out>) at ./src/qml/jsruntime/qv4managed_p.h:189 #3 QV4::MemoryManager::allocateObject<QV4::Object> (this=0x10000259f50, ic=0x0) at ./src/qml/memory/qv4mm_p.h:270 #4 QV4::MemoryManager::allocateObject<QV4::Object> (this=0x10000259f50) at ./src/qml/memory/qv4mm_p.h:280 #5 QV4::MemoryManager::allocate<QV4::Object> (this=0x10000259f50) at ./src/qml/memory/qv4mm_p.h:313 #6 0xfff80001011be530 in QV4::ExecutionEngine::ExecutionEngine (this=0x1000025bba0, jsEngine=<optimized out>, this=<optimized out>, jsEngine=<optimized out>) at ./src/qml/jsruntime/qv4engine.cpp:434 #7 0xfff80001011920a4 in QJSEngine::QJSEngine (this=0x7feffbeaf28, dd=..., parent=0x0, this=<optimized out>, dd=<optimized out>, parent=<optimized out>) at ./src/qml/jsapi/qjsengine.cpp:359 #8 0xfff8000101192184 in QJSEngine::QJSEngine (this=0x7feffbeaf28, parent=0x0, this=<optimized out>, parent=<optimized out>) at /usr/include/sparc64-linux-gnu/qt6/QtCore/qproperty.h:84 #9 0x0000010000000b6c in main (argc=1, argv=0x7feffbeb3b8) at qt6test.cpp:6 (gdb)
The cause for the crash seems to be that this is pointing to NULL.
My suspicion is that the existing moving around of pointer bits in src/qml/common/qv4staticvalue_p.h is either incomplete on sparc64 or not used at all:
#elif defined(Q_PROCESSOR_SPARC_64) // Sparc64 wants to use 52 bits for pointers. // Upper3 can stay where it is, bit48 moves to the top bit. Top1Shift = -15, Upper3Shift = 0, Lower5Shift = 0,
It has been suggested that adding an additional Q_ASSERT() in line 595 might help debugging this, testing this now:
Index: qt6-declarative-6.9.2+dfsg/src/qml/common/qv4staticvalue_p.h =================================================================== --- qt6-declarative-6.9.2+dfsg.orig/src/qml/common/qv4staticvalue_p.h +++ qt6-declarative-6.9.2+dfsg/src/qml/common/qv4staticvalue_p.h @@ -595,6 +595,7 @@ struct StaticValue storePointerBits<Upper3Shift, Upper3Mask>( storePointerBits<Lower5Shift, Lower5Mask>(tmp))); + Q_ASSERT(!(_val & ManagedMask)); QT_WARNING_POP } #elif QT_POINTER_SIZE == 4
Please note that there a SPARC machines running Solaris and Linux available in the GCC Compile Farm (https://gcc.gnu.org/wiki/CompileFarm) accessible by any open source developers.
This bug is also tracked on GitHub: https://github.com/sparclinux/issues/issues/26