Michael Codish

The standard operational semantics of concurrent constraint logic languages is not confluent in the sense that different schedulings of processes may result in different program behaviors. While implementations are free to choose specific scheduling policies, analyses should be correct for all implementations. Moreover, in the presence of parallelism it is usually not possible to determine how processes will actually be scheduled. Efficient program analysis is therefore difficult as all process schedulings must be cousidered. To overcome this problem we introduce a confluent semantics which closely approximates the standard (non-confluent) semantics. This semantics provides a basis for efficient and accurate program analysis for these languages. To illustrate the usefulness of this approach we sketch analyses based on abstract interpretations of the confluent semantics which determine if a program is suspension and local suspension free.