Generalized Loop-Unrolling: a Method for Program Speed-Up

It is well-known that, to optimize a program for speed-up, efforts should be focused on the regions where the payoff will be greatest. Loop constructs in a program represent such regions. In the literature, it has been shown that a certain degree of speed-up can be achieved by loop unrolling. The technique published so far, however, appears to be applicable to FOR-loops only. This paper presents a generalized loop-unrolling method that can be applied to any type of loop construct. Possible complications in its applications, together with some experimental results, are discussed in detail. Introduction There has been considerable effort to develop source-to-source transformation methods that restructure loop constructs to expose possibilities for parallelism. Most published loop restructuring methods are designed for countable loops, where the iteration count can be determined without executing the loop. One such method, called loop unrolling [2], is designed to unroll FOR loops for p..