Refining schizophrenia via graph reachability in Esterel

Esterel is an imperative synchronous language for control-dominant reactive systems. The combination of imperative structures and the perfect synchrony hypothesis often result in schizophrenic statements. Previous studies explain the characteristics of schizophrenia as the instantaneous reentrance to block statements: local signal declarations and parallel statements. In practice, however, most instantly-reentered block statements do not cause any problems in Esterel compilation. In this paper, we refine schizophrenic problems in terms of signal emissions, and suggest an algorithm to detect harmful schizophrenia using reachability on control flow graphs (CFGs) in Esterel. Our algorithm performs well in analyzing practical programs. Moreover, it can be easily applied to existing compilers.