PBExplore: A Framework for Compiler-in-the-Loop Exploration of Partial Bypassing in Embedded Processors

Abstract

Varying partial bypassing in pipelined processors is an effective way to make performance, area and energy tradeoffs in embedded processors. However, performance evaluation of partial bypassing in processors has been inaccurate, largely due to the absence of bypass-sensitive retargetable compilation techniques. Furthermore no existing partial bypass exploration framework estimates the power and cost overhead of partial bypassing. In this paper we present PBExplore: a framework for compiler-in-the-loop exploration of partial bypassing in processors. PBExplore accurately evaluates the performance of a partially bypassed processor using a generic bypass-sensitive compilation technique. It synthesizes the bypass control logic and estimates the area and energy overhead of each bypass configuration. PBExplore is thus able to effectively perform multidimensional exploration of the partial bypass design space. We present experimental results on the Intel XScale architecture on MiBench benchmarks and demonstrate the need, utility and exploration capabilities of PBExplore.