Software-Based Self-Testing Using Bounded Model Checking for Out-of-Order Superscalar Processors

Abstract

Generating functional tests for processors has been a challenging problem for decades in the very large-scale integration testing field. This paper presents a method that generates software-based self-tests by leveraging bounded model checking (BMC) techniques and targeting, for the first time, out-of-order [out-of-order execution (OOE)] superscalar processors. To combat the state-space explosion associated with BMC, the proposed method starts by combining module-level abstraction-refinement with slicing to reduce the size of the model under verification. Next, an off-the-shelf BMC solver is used on the obtained extended finite-state machines to generate the leading sequences that are necessary to excite internal processor functions. Finally, constrained automatic test-pattern generation is used to cover all structural faults within every function excited by the obtained leading sequences. Experimental results show that the proposed method leads to extremely high fault coverage on the critical components corresponding to OOE operations in functional mode. The method therefore helps in tackling the over-testing problem that is inherent to the full-scan test approach.