Implement support for ABI forwarding

[eschkufz]

Overview

ABI forwarding --- the optimization described in the asplos 19 paper which allows us to enter open-loop mode for programs which use standard library peripherals --- was only ever implemented in a proof of concept branch. As this is a key performance obstacle, we need to implement formal support for this feature.

An upcoming refactoring for file i/o tasks (which combined with existing support for arrays) will eliminate this issue for memories and fifos (which we'll be removing from the standard library).

Deliverables

• Formalize the implementation of ABI-forwarding