Lazy Array Data-Flow Dependence Analysis

Abstract

Automatic parallelization of real FORTRAN programs does not live up to users expectations yet, and dependence analysis algorithms which either produce too many false dependences or are too slow to contribute significantly to this. In this paper we introduce dataflow dependence analysis algorithm which exactly computes value-based dependence relations for program fragments in which all subscripts, loop bound and IF conditions are affine. Our algorithm also computes good affine approximations of dependence relations for non-affine program fragments. Actually, we do not know about any other algorithm which can compute better approximations.