Loop Unrolling in Multi-pipeline ASIP Design

Application Specific Instruction-set Processor (ASIP) is one of the popular processor design techniques for embedded systems which allows customizability in processor design without overly hindering design flexibility. Multi-pipeline ASIPs were proposed to improve the performance of such systems by compromising between speed and processor area. One of the problems in the multi-pipeline design is the limited inherent instruction level parallelism (ILP) available in applications. The ILP of application programs can be improved via a compiler optimization technique known as loop unrolling. In this paper, we present how loop unrolling effects the performance of multi-pipeline ASIPs. The improvements in performance average around 15% for a number of benchmark applications with the maximum improvement of around 30%. In addition, we analyzed the variable of performance against loop unrolling factor, which is the amount of unrolling we perform.