1 New Analytical Model of Value Prediction

Abstract:- Value prediction is a technique for speculative execution of data dependent instructions based on predicted outcomes of instructions. The predicted outcomes are supplied by a special hardware device called value predictor. Despite the numerous reports on the benefits of value prediction there is still no commercial processor that employs this technique. One limiting factor of the performance potential of value prediction is the value predictor latency. In this paper we extend an existing analytical model of the processor in order to evaluate the effect of value predictor latency. We conclude that the value predictor latency must be reduced and value prediction latency should be overlapped by some other pipeline stages. In addition, value prediction should be made only on instructions with high execution latencies