Concurrency Analysis for Shared Memory Programs with Textually Unaligned Barriers

Concurrency analysis is a static analysis technique that determines whether two statements or operations in a shared memory program may be executed by different threads concurrently. Concurrency relationships can be derived from the partial ordering among statements imposed by synchronization constructs. Thus, analyzing barrier synchronization is at the core of concurrency analyses for many parallel programming models. Previous concurrency analyses for programs with barriers commonly assumed that barriers are named or textually aligned. This assumption may not hold for popular parallel programming models, such as OpenMP, where barriers are unnamed and can be placed anywhere in a parallel region, i.e., they may be textually unaligned. We present in this paper the first interprocedural concurrency analysis that can handle OpenMP, and, in general, programs with unnamed and textually unaligned barriers. We have implemented our analysis for OpenMP programs written in C and have evaluated the analysis on programs from the NPB and SpecOMP2001 benchmark suites.