Dual-Stack Return Address Predictor

Abstract

Return address predictors used currently almost have the same architecture: a return address stack and a top-of-stack pointer, some of which may be enhanced by repair mechanisms. The disadvantage of this type of return ad-dress predictor is that either prediction accuracy is low or the hardware cost is high. In this paper, we present a novel kind of return address prediction structure called Dual-Stack Return Address Predictor (DSRAP) which contains two return address stacks: RAS_PRED and RAS_WRB. Just as the return address stack in current return address predictors does, RAS_PRED provides predicted target addresses for procedure returns. RAS_WRB provides data for repairing RAS_PRED when a branch misprediction is detected. Results show that DSRAP can acquire 100% hit rates if mispredictions caused by unmatched call/return sequences or the stack overflow are ignored. Furthermore, DSRAP is very easy to design.