超标量处理器中寄存器别名表恢复方法的改进研究  

Improvement study on recovery method of RAT in superscalar processors

作　　者：杨思博 黎炜桁 于敦山[1] 祖靖昭 李世平 Yang Sibo;Li Weiheng;Yu Dunshan;Zu Jingzhao;Li Shiping(School of Software&Microelectronics,Peking University,Beijing 102600,China;Jiangsu Huachuang Microsystem Co.Ltd.,Nanjing 210000,China)

机构地区：[1]北京大学软件与微电子学院,北京102600 [2]江苏华创微系统有限公司,南京210000

出　　处：《计算机应用研究》2022年第12期3701-3705,3712,共6页Application Research of Computers

基　　金：军队科研资助项目。

摘　　要：寄存器重命名是超标量处理器用于提升指令集并行度的重要方法,其基本实现方式是通过寄存器别名表来记录逻辑寄存器和物理寄存器的映射关系,当发生分支预测错误时需要对寄存器别名表中的内容进行恢复。针对于现有的恢复方法没有利用重命名的局部性特征,在处理器的指令窗口增加时暴露出实现代价过大的问题,提出了一种基于区间进行寄存器别名表恢复的改进型恢复方法,通过对walk方法的改造,使用区间计分板来确定需要扫描的地址范围,并精确地控制每个区间的扫描,可以大大减小资源浪费。通过对逻辑综合结果和性能进行分析,相比于检查点恢复的传统设计,这种方法使用更少的面积和功耗,达到与检查点方式恢复接近的性能,也具有更好的扩展潜力。Register renaming is a critical component of modern superscalar processor to exploit the instruction level paralle-lism,the foundation of it is to record the mappings between logical registers and physical registers in the RAT.If the branch prediction is error,the RAT needs to recover to the status at the branch.The commonly used recovery methods don’t take advantage of the locality of renaming,as instruction window size increases,all of them exposit the problem of too costly.This paper proposed a region-based rename recovery method,by modify the walk method,used region scoreboards to determine the range of addresses to be scanned,and precisely controlled the scan process in each region,resource waste could be greatly reduced.Through the analysis of synthesis and performance reports,this method’s performance is close to the traditional checkpoint recovery method with much less area and power,and has better expansion potential.

关 键 词：寄存器重命名 寄存器别名表 计分板 重命名历史扫描 

分 类 号：TN47[电子电信—微电子学与固体电子学]