[GrygrFlzr]

Does this make it more difficult to reason about the program memory usage over its lifetime, or can all potential cases be statically analyzed?

[kmill]

The paper is about trying to statically analyze this. As I understand it, fip-annotated functions are ones that are checked to neither allocate nor deallocate.

[tuukkah]

Seems easy and clear: they introduce a keyword "fip" that you use to mark a function as being fully in-place, and they statically check it.