Abstract. Java's annotation mechanism allows us to extend its type system with non-null types. However, checking such types cannot be done using the existing bytecode verification algorithm. We extend this algorithm to verify non-null types using a novel technique that identifies aliasing relationships between local variables and stack locations in the JVM. We formalise this for a subset of Java Bytecode and report on experiences using our implementation.

Abstract-Ownership and related systems impose restrictions on the object graph that can help improve program structure, exploit concurrency and verify software. Such systems rely on the presence of appropriate ownership annotations in the source code. Unfortunately, manually adding ownership annotations to legacy systems is a tedious process. Previous attempts at automatically inferring such ownership systems do not produce modularly checkable annotations (i.e. which allow classes to be checked in isolation) making them difficult to incorporate into day-today development. In this paper, we present OwnKit -a system for automatically inferring ownership annotations which are modularly checkable. We describe and evaluate our approach on a number of real-world benchmarks and compare against an existing system.

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<p>Object ownership allows us to statically control run-time aliasing in order to provide a strong notion of object encapsulation. Unfortunately in order to use ownership, code must first be annotated with extra type information. This imposes a heavy burden on the programmer, and has contributed to the slow adoption of ownership. Ownership inference is the process of reconstructing ownership type information based on the existing ownership patterns in code. This thesis presents OwnKit—an automatic ownership inference tool for Java. OwnKit conducts inference in a modular way: by only considering a single class at the time. The modularity makes our algorithm highly scalable in both time and memory usage.</p>

<p>Object ownership allows us to statically control run-time aliasing in order to provide a strong notion of object encapsulation. Unfortunately in order to use ownership, code must first be annotated with extra type information. This imposes a heavy burden on the programmer, and has contributed to the slow adoption of ownership. Ownership inference is the process of reconstructing ownership type information based on the existing ownership patterns in code. This thesis presents OwnKit—an automatic ownership inference tool for Java. OwnKit conducts inference in a modular way: by only considering a single class at the time. The modularity makes our algorithm highly scalable in both time and memory usage.</p>