The Costs and Benefits of Java Bytecode Subroutines

Java bytecode subroutines are used to compile the Java source language try-finally construct into a succinct combination of special-purpose instructions. However, the space saved by using subroutines, in comparison to simpler compilation strategies, comes at a substantial cost to the complexity of the bytecode verifier and other parts of the Java Virtual Machine. This paper examines the trade-offs between keeping subroutines and eliminating them from the Java bytecode language. We compare the cost of formally specifying the bytecode verifier and implementing the Java Virtual Machine in the presence of subroutines to the space saved by using them when compiling a set of representative Java programs.