High-level modeling and FPGA prototyping of microprocessors

Emerging high-level hardware description and synthesis technologies in conjunction with field-programmable gate arrays (FPGAs) have significantly lowered the threshold for hardware development. Opportunities exist to integrate these technologies into a tool for exploring and evaluating microarchitectural designs. This paper presents a case study in developing the synthesizable high-level model of a superscalar processor and producing a working prototype in FPGA. Using an experimental operation-centric hardware description language, we have created the synthesizable model of a superscalar speculative out-of-order core for the integer subset of SimpleScalar PISA. A prototype implementation is produced by synthesizing the high-level model for the Spyder FPGA prototyping board. In addition, we have modified the baseline processor model to create derivative processor designs that add newly proposed experimental mechanisms. The derivative models are useful both in testing the completeness and correctness of new mechanisms and in assessing the mechanisms' impact on implementation area and cycle time.