Towards Array Bound Check Elimination in Java Virtual Machine Language

The Java Virtual Machine Language (JVML) is a platform independent programming language at bytecode level. A Java program is compiled into JVML bytecode in a standard Java implementation, which may be transferred across networks to various hosts and then interpreted by the Java Virtual Machine. Note that these hosts may not trust the source of the bytecode. For safety concerns, JVML disallows out-of-bounds array access. In practice, this is enforced through run-time array bounds checking. Unfortunately, this practice can be prohibitively expensive in cases involving numerical computation such as animation. In this paper, we propose a type-theoretic approach to eliminating run-time array bound checks in JVML and demonstrate that the property of safe array access can be readily captured with a restricted form of dependent type system and therefore enforced through type-checking. We focus on a language JVMLa, which is basically a subset of JVML with array access instructions, and prove that the execution of a well-typed JVMLa program can never cause memory violations.