Circuit Retiming Applied to Decomposed Software Pipelining

| This paper elaborates on a new view on software pipelining, called decomposed software pipelining, and introduced The approach is to decou-ple the problem into resource constraints and dependence constraints. Resource constraints management amounts to scheduling an acyclic graph subject to processors constraints , a problem for which an eeciency bound is known, resulting in a bound for loop scheduling. The acyclic graph is obtained by cutting some particular edges of the (cyclic) dependence graph. In this paper, we cut edges in a diier-ent way, using circuit retiming algorithms, so as to minimize both the longest dependence path in the acyclic graph, and the number of edges in the acyclic graph. With this technique , we improve the eeciency bound given for Gasper-oni and Schwiegelshohn algorithm, and we reduce the constraints that remain for the acyclic problem. We believe this framework to be of interest because it brings a new insight to the software pipelining problem by establishing its deep link with the circuit retiming problem.