Polynomial Formal Verification of a RISC-V Processor

Verification plays a major role in ensuring the functional correctness of any design. In recent years with growing complexity of processor designs, verification has assumed utmost importance. Simulation-based techniques cannot ensure completeness in verification, and in this regard formal methods prove crucial. Although formal methods guarantee completeness it is hard to quantify the exact time and space complexities. Recently some works have demonstrated that it is possible to achieve polynomial space and time complexities for various arithmetic circuits as well as for processors. In this paper we propose a Binary Decision Diagram (BDD) based Polynomial Formal Verification (PFV) approach for verifying processors. As a case study, we discuss the PFV for a multi-cycle processor (viz., MicroRV32) with support for combinational and sequential sub-systems. New data structures and code base are utilized to verify all the functional components. Experimental results reveal that the verification can indeed be performed in polynomial time.