Hierarchical Pipelining of Nested Loops in High-Level Synthesis

Abstract

Pipelining of the nested loops is very important in increasing the throughput of a system developed by a high-level synthesis tool. The most pipelining methods can handle only single loops. Therefore, nested loops are converted into a single loop, called loop flattened loop. In consequence, i.e. the sequential loops cannot be implemented in separate pipeline stages. This constraint limits the throughput. In this paper, a novel method are presented for nested loops by implementing to avoid this limitation. The method has the advantage that the desired restart time of the whole system can be given as an input parameter. The necessity of the pipeline scheduling on each loop hierarchy level can also be determined by this method. A novel multirate dataflow graph is also introduced for modeling the nested loops in an easy and abstract way.