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Abstract: “Optimizing compilers, including those in virtual machines, commonly utilize Static Single Assignment Form as their intermediate representation, but interpreters typically im- plement stack-oriented virtual machines. This paper intro- duces an easily interpreted variant of Static Single Assign- ment Form. Each instruction of this Interpretable Static Single Assignment Form, including the Phi Instruction, has self-contained operational semantics facilitating efficient in- terpretation. Even the array manipulation instructions pos- sess directly-executable single-assignment semantics. In ad- dition, this paper describes the construction of a prototype virtual machine realizing Interpretable Static Single Assign- ment Form and reports on its performance.”