On Thursday, 8 September 2016 at 10:44:55 UTC, Stefan Koch wrote:

compiling parts of phobos does no longer crash the new engine.
However it still produces incorrect byte-code :)

I think I have taken care of the incorrect bytecode.
It was not an issue with the engine itself but rather with the way I plugged it in.
The new engine is not supposed being called if the old one has already started to interpret the function, because the two do not and should not share state.