Iterative module scheduling

Module scheduling is a framework within which algorithms for software pipelining innermost loops may be defined. The Framework specifies a set of constraints that must be met in order to achieve a legal module schedule. A wide variety of algorithms and heuristics can be defined within this framework. Little work has been done to evaluate and compare alternative algorithms and heuristics for module scheduling from the viewpoints of schedule quality as well as computational complexity. This, along with a vague and unfounded perception that module scheduling is computationally expensive as well as difficult to implement, have inhibited its incorporation into product compilers. This paper presents iterative module scheduling, a practical algorithm that is capable of dealing with realistic machine models. The paper also characterizes the algorithm in terms of the quality of the generated schedules as well the computational expense incurred.