FAST, EFFECTIVE DYNAMIC COMPILATION

Dynamic compilation enables optimizations based on the values of invar iant data computed at run-time. Using the values of these runtime cons tants, a dynamic compiler can eliminate their memory loads, perform co nstant propagation and folding, remove branches they determine, and fu lly unroll loops they bound. However, the performance benefits of the more efficient, dynamically-compiled code are offset by the run-time c ost of the dynamic compile. Our approach to dynamic compilation strive s for both fast dynamic compilation and high-quality dynamically-compi led code: the programmer annotates regions of the programs that should be compiled dynamically; a static, optimizing compiler automatically produces pre-optimized machine-code templates, using a pair of dataflo w analyses that identify which variables will be constant at run-time; and a simple, dynamic compiler copies the templates, patching in the computed values of the run-time constants, to produce optimized, execu table code. Our work targets general purpose, imperative programming l anguages, initially C. Initial experiments applying dynamic compilatio n to C programs have produced speedups ranging from 1.2 to 1.8.