Global Optimization of Compositional Systems

Embedded systems typically consist of a composition of a set of hardware and software IP modules. Each module is heavily optimized by itself. However, when these modules are composed together, significant additional opportunities for optimizations are introduced because only a subset of the entire functionality is actually used. We propose COSE-a technique to jointly optimize such designs. We use symbolic execution to compute invariants in each component of the design. We propagate these invariants as constraints to other modules using global flow analysis of the composition of the design. This captures optimizations that go beyond, and are qualitatively different than, those achievable by compiler optimization techniques such as common subexpression elimination, which are localized. We again employ static analysis techniques to perform optimizations subject to these constraints. We implemented COSE in the Metropolis platform and achieved significant optimizations using reasonable computational resources.