Purity Analysis:An Abstract Interpretation Formulation

摘要

Salcianu and Rinard present a compositional purity analysis that computes a summary for every procedure describing its side-effects. In this paper, we formalize a generalization of this analysis as an abstract interpretation, present several optimizations and an empirical evaluation showing the value of these optimizations. The Salcianu-Rinard analysis makes use of abstract heap graphs, similar to various heap analyses and computes a shape graph at every program point of an analyzed proce-dure. The key to our formalization is to view the shape graphs of the analysis as an abstract state transformer rather than as a set of abstract states: the concretization of a shape graph is a function that maps a concrete state to a set of concrete states. The abstract interpretation formulation leads to a better understanding of the algorithm. More im-portantly, it makes it easier to change and extend the basic algorithm, while guaranteeing correctness, as illustrated by our optimizations.