基于xorHash的RISC-V分支预测器设计  

Design of RISC-V branch predictor based on xorHash

作　　者：苗恒 曲英杰[1] MIAO Heng;QU Yingjie(College of Information Science and Technology,Qingdao University of Science and Technology,Qingdao 266061,China)

机构地区：[1]青岛科技大学信息科学技术学院,山东青岛266061

出　　处：《电子设计工程》2024年第24期58-62,67,共6页Electronic Design Engineering

摘　　要：处理器的高速发展对分支预测器准确度要求越来越高,通过研究RISC-V处理器中分支预测器微架构,设计了基于xorHash的分支预测器;在基于xorHash的分支预测器中,使用改进后的xorHash算法对分支跳转指令进行散列处理,降低了别名发生概率,并提高了预测准确率;将分支预测器接入RISC-V五级流水线架构,利用Verilator仿真验证了改进后的分支预测器的准确率,通过板级测试评估了其性能;结果表明,分支预测器在运行CoreMark时准确率达到99.57%,在运行Dhrystone时准确率达到97.57%。The rapid development of processors requires more and more accuracy of branch predictors.By studying the microarchitecture of the branch predictor in the RISC-V processor,a branch predictor based on xorHash was designed.In the branch predictor based on xorHash,the improved xorHash algorithm is used to hash the branch jump instructions,which reduces the probability of alias occurrence and improves the prediction accuracy.The branch predictor was connected to the RISC-V five-stage pipeline architecture,and the accuracy of the improved branch predictor was verified by Verilator simulation,and its performance was evaluated by board-level testing.The results show that the branch predictor accuracy reaches 99.57%when running CoreMark and 97.57%when running Dhrystone.

关 键 词：RISC-V 处理器 分支预测器 xorHash BTB 

分 类 号：TN492[电子电信—微电子学与固体电子学]