On this ABI, pointers are 32-bit, so Qt::HANDLE (void *) is a 32-bit variable and the "movq" instruction is inappropriate. There's a GCC extended inline assembler modifier for the instruction size suffix (%z0) but Clang seems not to understand it. Instead, I just removed the suffix: we can do that because this is a memory load instruction, which implies the destination is a general purpose register (also required by the "=r" constraint) and therefore the assembler can determine the size of the memory load from the name of the selected register. Note: I did not verify this compiles on x32 at all, much less that it loads the right thing from memory. Fixes: QTBUG-122674 Pick-to: 6.5 6.6 6.7 Change-Id: I01ec3c774d9943adb903fffd17b6513d146e89ce Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io> Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>