An Improving Method for Loop Unrolling.

In this paper we review main ideas mentioned in several other papers which talk about optimization techniques used by compilers. Here we focus on loop unrolling technique and its effect on power consumption, energy usage and also its impact on program speed up by achieving ILP (Instruction-level parallelism). Concentrating on superscalar processors, we discuss the idea of generalized loop unrolling presented by J.C. Hang and T. Leng and then we present a new method to traverse a linked list to get a better result of loop unrolling in that case. After that we mention the results of some experiments carried out on a Pentium 4 processor (as an instance of super scalar architecture). Furthermore, the results of some other experiments on supercomputer (the Alliat FX/2800 System) containing superscalar node processors would be mentioned. These experiments show that loop unrolling has a slight measurable effect on energy usage as well as power consumption. But it could be an effective way for program speed up.