Specification-based compaction of directed tests for functional validation of pipelined processors

Functional validation is a major bottleneck in microprocessor design methodology. Simulation is the widely used method for functional validation using billions of random and biased-random test programs. Although directed tests require a smaller test set compared to random tests to achieve the same functional coverage goal, there is a lack of automated techniques for directed test generation. Furthermore, the number of directed tests can still be prohibitively large. This paper presents a methodology for specification-based coverage analysis and test generation. The primary contribution of this paper is a compaction technique that can drastically reduce the required number of directed test programs to achieve a coverage goal. Our experimental results using a MIPS processor and an industrial processor (e500) demonstrate more than 90% reduction in number of directed tests without sacrificing the functional coverage goal.