Abstract

In this paper, we investigate the problem of optimizing array accesses across a collection of loops. We demonstrate that a good solution to such a problem should be based on an optimization scheme, called collective loop transformations, that considers all loops simultaneously. In particular, loop reversal, loop interchange and loop fusion are performed collectively on a set of loop nests. The main impact of these transformations is an optimization called array contraction, that saves space and time by converting an array variable into a scalar variable or a buffer containing a small number of scalar variables. This optimization is applicable to general-purpose high-performance architectures. For a multiprocessor architecture, array contraction is performed by executing the producer and consumer loops on separate processors, and by using a smaller buffer for the array communication. For a uniprocessor architecture, array contraction is performed by fusing the producer and consumer loop...

Citations