Clockhands: Rename-free Instruction Set Architecture for Out-of-order Processors
Toru Koizumi, Ryota Shioya, Shu Sugita, Taichi Amano, Yuya Degawa, Junichiro Kadomoto, Hidetsugu Irie, Shuichi Sakai · 2023
Out-of-order superscalar processors are currently the only architecture that speeds up irregular programs, but they suffer from poor power efficiency. To tackle this issue, we focused on how to specify register operands. Specifying operands by register names, as conventional RISC does, requires register renaming, resulting in poor power efficiency and preventing an increase in the front-end width. In contrast, a recently proposed architecture called STRAIGHT specifies operands by inter-instruction distance, thereby eliminating register renaming. However, STRAIGHT has strong constraints on instruction placement, which generally results in a large increase in the number of instructions.