Source-level optimization of run-time program generators

We describe our efforts to use source-level rewriting to optimize run-time program generators written in Jumbo, a run-time program generation system for Java. Jumbo is a compiler written in compositional style, which brings the advantage that any program fragment can be abstracted out and compiled to an intermediate form. These forms can be put together at run-time to build complete programs. This principle provides a high level of flexibility in writing program generators. However, this comes at the price of inefficient run-time compilation. Using source-level transformations, we optimize the run-time generation of byte code from fragments, achieving speedups of 5–15%. We discuss the optimization process and give several examples.