A Quantitative Algorithm for Data Locality Optimization

In this paper, we consider the problem of optimizing register allocation and cache behavior for loop array references. We exploit techniques developed initially for data locality estimation and improvement in the framework of cache or local memories. First we review the concept of \reference window" that serves as our basic tool for both data locality evaluation and management. Then we study how some loop restructuring techniques (interchanging, tiling,...) can help improve data locality. We describe a register allocation algorithm and a cache usage optimization algorithm based on the window concept which can be eeectively implemented in a compiler system. Experimental speedup measurements on a RISC processor, the IBM RS/6000, give evidence of the eeciency of our technique.