Application structure-aware caching on Nemo

Nemo has a policy layer that allows powerful optimization with configurable runtime modules. In terms of caching, it is possible to identify frequently used data and decide to cache them in-memory ahead of execution, without user annotation.

Implementation would need:

• On policy layer, build compile-time pass that identify reused data and mark them as cached
• On runtime, design and implement caching mechanism that manages per-executor cached data and discard them when these are no longer used.