Maximum Throughput Loop Pipelining with Register Optimization Maximum Throughput Loop Pipelining with Register Optimization

This paper presents UNRET (unrolling and retiming), a new approach for resource-constrained loop pipelining. UNRET aims at nding a loop schedule with maximum throughput and minimum register pressure. UNRET is composed of two main phases. In the rst phase, a schedule with maximum throughput is found for a given set of resource constraints. To do so, diierent unrolling degrees are explored in decreasing order of throughput. For each theoretical throughput, both the unrolling degree of the loop and the expected initiation interval of the schedule are analytically computed by using new and eeective methods. In the second phase, the number of registers required by the schedule is reduced while maintining the throughput. The eeectiveness of UNRET has been proven by presenting results on well-known benchmarks. The obtained results show that UNRET may obtain faster schedules than other approaches, also reducing the register pressure.