Retiming DAGs

Abstract

This paper is devoted to a low-complexity algorithm for retiming circuits without cycles, i.e. whose network graph is a Direct Acyclic Graph (DAG). On one hand DAGs have a great practical importance, as shown by the on-line arithmetic circuits used as a target application in this paper. On the other hand retiming is a costly design optimization technique, in particular when applied to large circuits. Hence the need to design a specialized retiming algorithm to handle DAGs more eciently than general-purpose retiming algorithms. Our algorithm dramatically improves on current solutions in the literature: we gain an order of magnitude in the worst-case complexity, and we show convincing experimental results at the end of the paper