Using abstract interpretation to add type checking for interfaces in Java bytecode verification

Abstract

Java interface types support multiple inheritance. Because of this, the standard bytecode verifier ignores them, since it is not able to model the class hierarchy as a lattice. Thus, type checks on interfaces are performed at run time. We propose a verification methodology that removes the need for run-time checks. The methodology consists of: (1) an augmented verifier that is very similar to the standard one, but is also able to check for interface types in most cases; (2) for all other cases, a set of additional simpler verifiers, each one specialized for a single interface type. We obtain these verifiers in a systematic way by using abstract interpretation techniques. Finally, we describe an implementation of the methodology and evaluate it on a large set of benchmarks.