DFlows: A Flow-based Programming Approach for a Polyglot Design-Space Exploration Framework

Current architectural Design-Space Exploration (DSE) tools specify the exploration problem through annotations or pragmas. However, this approach is inherently language-dependent and limits the applicability to one specific target language and synthesis toolchain. Additionally, the rapid development of new hardware Domain-Specific Languages, programming models, and different exploration heuristics calls for a language-agnostic and modular approach. To address this need, we present a DSE formalization to facilitate the integration of new components and customized flows and leverage it to implement DFlows, a flow-based-programming DSE tool that decouples problem definition, code generation, exploration, and evaluation strategies. DFlows’s compiler-based frontend provides language-agnostic generation of design points through Abstract Syntax Tree manipulation. We show how DFlows can integrate custom performance models from complex state-of-the-art accelerators for Verilog, VHDL, Chisel, and HLS designs. We compare the runtimes of our DSE process against a state-of-the-art Chisel-based DSE tool, achieving up to 3.74× speedup while identifying the same set of optimal solutions. Additionally, we integrate in DFlows a custom exploration heuristic leveraging genetic algorithms and a novel online learning fitness function approximation methodology. This approximation yields a negligible hypervolume difference with the exhaustive search Pareto-front while improving DSE runtime by up to 2.67×.