A fast algorithm for code movement optimisation

Abstract

Code optimisation algorithms using bi-directional data flow dependencies have become increasingly important in recent years. The use of these algorithms faces two difficulties in practice: (a) Low profitabilities, and (b) high solution costs. This paper develops a new approach to the use of bi-directional dependencies using the concept of edge placement . This is shown to yield higher profitabilities of optimisation. An efficient solution method for such algorithms is also developed. The complexity of this method is shown to be bounded by O(e) operations, where e is the number of edges in the program flow graph. Ths is comparable to the complexity of uni-directional flow algorithms commonly used in optimisation.