This does not occur with mesa 18.2.0 and llvm 6.
There is no interesting output from wine nor any mention in dmesg.
This still occurs with mesa-git and llvm-svn.
Graphics card is vega 56
Seems to definitely be a mesa issue and not llvm, built mesa 18.2.0 with latest llvm and the issue does not occur. Will attempt to bisect
Did you bisect?