> Is this the key piece that makes sure we handle the `__morestack` prelude correctly?
It's necessary for any kind of function, with and without segmented stack. It's probably best if I add a section about function prologues and line information at the beginning of the file, since the functionality spans across multiple functions here...

But it's definitely a good idea to add a bit of explanation on these topics. Thanks for you suggestions, Huon!