Region inference for an object-oriented language

Abstract

Region-based memory management offers several important potential advantages over garbage collection, including real-time performance, better data locality, and more efficient use of limited memory. Researchers have advocated the use of regions for functional, imperative, and object-oriented languages. Lexically scoped regions are now a core feature of the Real-Time Specification for Java (RTSJ). Recent research in region-based programming for Java has focused on region checking, which requires manual effort to augment the program with region annotations. In this paper, we propose an automatic region inference system for a core subset of Java. To provide an inference method that is both precise and practical, we support classes and methods that are region-polymorphic, with region-polymorphic recursion for methods. One challenging aspect is to ensure region safety in the presence of features such as class sub-typing, method overriding, and downcast operations. Our region inference rules can handle these object-oriented features safely without creating dangling references.