Decomposed software pipelining: A new perspective and a new approach

Software pipelining is an efficient instruction-level loop scheduling technique, but existing software pipelining approaches have not been widely used in practical and commercial compilers. This is mainly because resource constraints and the cyclic data dependencies make software pipelining very complicated and difficult to apply. In this paper we present a new perspective on software pipelining in which it is decomposed into two subproblems—one is free from cyclic data dependencies and can be effectively solved by the list scheduling technique, and the other is free from resource constraints and can be easily solved by classical polynomial-time algorithms of graph theory. Based on this new perspective, we develop a new instruction-level loop scheduling approach, call DEcomposed Software Pipelining (DESP).