UPC-SPIN : A Framework for the Model Checking of UPC Programs ∗

This paper presents a software framework for the model check ing of the inter-thread synchronization functionalities of Un ified Parallel C (UPC) programs. The proposed framework includes a fron tend compiler that generates finite models of UPC programs in t he modeling language of the SPIN model checker. The model gener ation is based on a set of abstraction rules that transform th e UPC synchronization primitives to semantically-equivalent c ode snippets in SPIN’s modeling language. The back-end includes SPI N that verifies the generated model. If the model checking succ eeds, then the UPC program is correct with respect to properties of interest such as data race-freedom and/or deadlock-freedom. Oth erwise, the back-end provides feedback as sequences of UPC instructions that lead to a data race or a deadlock from initial states , called counterexamples . Using the UPC-SPIN framework, we have detected design flaws in several real-world UPC applications, including a program simulating heat flow in metal rods, parallel bub ble sort, parallel data collection, and an integer permutation program. More importantly, for the first time (to the best of our knowle dg ), we have mechanically verified data race-freedom and deadloc kfreedom in a UPC implementation of the Conjugate Gradient (C G) kernel of the NAS Parallel Benchmarks (NPB). We believe that UPC-SPIN provides a valuable tool for developers towards in creasing their confidence in the computational results generated by UPC applications.