Donald Bren School of Information and Computer Sciences

Optimizing compilers, including those in virtual machines, commonly utilize Static Single Assignment Form as their intermediate representation, but interpreters typically implement stack-oriented virtual machines. This paper introduces an easily interpreted variant of Static Single Assignment Form. Each instruction of this Interpretable Static Single Assignment Form, including the Phi Instruction, has self-contained operational semantics facilitating efficient interpretation. Even the array manipulation instructions possess directly-executable single-assignment semantics. In addition, this paper describes the construction of a prototype virtual machine realizing Interpretable Static Single Assignment Form and reports on its performance.