Dual-Stack Return Address Predictor

摘要

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 address 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.