Automating formal verification of customized soft-processors

Soft-processors, instruction processors implemented in FPGA technology, are often customizable to support domain-specific optimization. However the correctness of customized soft-processors, executing the associated machine code, is often not obvious. This paper proposes a novel approach for verifying the implementation of an application program for a customized soft-processor, based on the ACL2 theorem prover. The correctness proof involves verifying a machine code program executing on the target hardware device against a high-level specification of the application program. We illustrate the proposed approach with several case studies, showing how processors with different custom instructions and with different number of pipelined stages can be automatically produced and verified; such processors have a range of trade-offs in performance, size, power and energy consumption to meet different requirements.