StagedSAC: a case study in performance-oriented DSL development

Domain-specific languages (DSLs) can bridge the gap between high-level programming and efficient execution. However, implementing compiler tool-chains for performance oriented DSLs requires significant effort. Recent research has produced methodologies and frameworks that promise to reduce this development effort by enabling quick transition from library-only, purely embedded DSLs to optimizing compilation. In this case study we report on our experience implementing a compiler for StagedSAC. StagedSAC is a DSL for arithmetic processing with multidimensional arrays modeled after the stand-alone language SAC (Single Assignment C). The main language feature of both SAC and StagedSAC is a loop construction that enables high-level and concise implementations of array algorithms. At the same time, the functional semantics of the two languages allow for advanced compiler optimizations and parallel code generation. We describe how we were able to quickly evolve from a pure library DSL to a performance-oriented compiler with a good speedup and only minor syntax changes using the technique of Lightweight Modular Staging. We also describe the optimizations we perform to obtain fast code and how we plan to generate parallel code with minimal effort using the Delite framework.