COVERAGE-DRIVEN TEST GENERATION FOR FUNCTIONAL VALIDATION OF PIPELINED PROCESSORS By HEON-MO KOO A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY

of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy COVERAGE-DRIVEN TEST GENERATION FOR FUNCTIONAL VALIDATION OF PIPELINED PROCESSORS By Heon-Mo Koo December 2007 Chair: Prabhat Mishra Major: Computer Engineering Functional verification of microprocessors is one of the most complex and expensive tasks in the current system-on-chip design methodology. Simulation using functional test vectors is the most widely used form of processor verification. A major challenge in simulation-based verification is how to reduce the overall verification time and resources. Traditionally, billions of random and directed tests are used during simulation. Compared to random tests, directed tests can reduce overall validation effort significantly since shorter tests can obtain the same coverage goal. However, there is a lack of automated techniques for directed test generation targeting micro-architectural design errors. Furthermore, the lack of a comprehensive functional coverage metric makes it difficult to measure the verification progress. This dissertation presents a functional coverage-driven test generation methodology. Based on the behavior of pipelined processors, a functional coverage is defined to evaluate the verification progress. My research provides efficient test generation techniques using formal methods by decomposing processor designs and properties to reduce test generation time as well as memory requirement. My research also provides a functional test compaction technique to reduce the number of directed tests while preserving the overall functional coverage. The experiments using MIPS and PowerPC processors demonstrate the feasibility and usefulness of the proposed functional test generation methodology.