Prediction and speculation techniques in ILP

Abstract

In this article we review the concepts of branch, value and meniory prediction used in conjunction with control and Liata speculative execution in superscalm processors. Since the amount of available instruction level parallelism within a basic block is relatively small, control speculation techniques increase the number of candidate instructions for execution. Moreover, the integration of value and memory prediction in superscalar processors introduces a new kind of speculative execution. Data Jpeculation techniques allow the processor to execute instructions beyond the limit of true data RAW depemkncies. We identifi data speculation as a natural extension of control speculation and capture their similarities and diflerences. We also raise a new question: is the analytical mockelling approach really infeasible?