Deoptimization is actually really hard to implement if you have an ahead of time compiler like Cannoli. You need to get all the stuff that is living in machine registers or in the C stack and then convert them back to whatever representation your generic interpreter uses.

I think this is actually one of the things that most get in the way if you want to use traditional AOT compiler technology (like gcc or LLVM) to implement a JIT. In state of the art JIT compilers this part is always a nest of highly complex and nonportable assembly language.