两级分配多可用重命名寄存器

Multi-Usable Rename Register with 2-Level Renaming and Allocating

提出了一种新的寄存器重命名机制———两级分配多可用重命名寄存器,简称2L-MuRR,其特点如下:(1)对重命名寄存器文件(RRF)的占用要经过两级重命名和分配过程,减少了无效占用时间.(2)RRF被划分为多个不同宽度的字段,根据目标值的大小进行按字段分配,这样使每个重命名寄存器都是多可用的.(3)同一重命名寄存器内的多个目标值的写(或读)操作可以合并成一次完成,减少了RRF的访问次数和读/写端口的压力.模拟实验表明,2L-MuRR显著提高了RRF的存储能力(70%以上),能以较少的重命名寄存器满足SMT高并行度的要求,有效缓解了寄存器文件的设计压力.

Great challenges must be overcome for designing the register file for SMT architecture. This paper proposes a novel register renaming scheme—Multi-usable Rename Register with 2-Level Renaming and Allocating （2L-MuRR）, which features as follows. First, each renamed value undergoes 2-level of renaming and allocating before write-back to the Rename Register File （RRF）, reducing useless occupancy. Second, the RRF is partitioned into several fields with different widths; either a single field or a field combination can be allocated to hold a renamed value, making each rename register multi-usable. Third, each access to a rename register may read or write multiple values in it, alleviating the pressure on the read/write ports. The simulations show that 2L-MuRR improves the RRF capacity greatly, over 70%. By using 2L-MuRR, SMT can achieve the same high performance with fewer rename registers, effectively reducing the design pressure on the register file.