Extending typestate analysis to multiple interacting objects

Abstract

This paper extends static typestate analysis to temporal specifications of groups of interacting objects, which are expressed using tracematches. Unlike typestate, a tracematch state may change due to operations on any of a set of objects bound by the tracematch. The paper proposes a lattice-based operational semantics equivalent to the original tracematch semantics but better suited to statis analysis. The paper defines a statis analysis that computes precise local points-to sets and tracks the flow of individual objects, thereby enabling strong state updates of the tracematch state. The analysis has been proved sound with respect to the semantics. A context-sensitive version of the analysis has been implemented as instances of the IFDS and IDE algorithms. The analysis was evaluated on tracematches used in earlier work and found to be very precise. Remaining imprecisions could be eliminated with more precise modeling of references from the heap and of exceptional control flow.