Microarchitectural Support for Speculative Register Renaming

This paper proposes and evaluates a new microarchitecture for out-of-order processors that supports speculative renaming. We call speculative renaming to the speculative omission of physical register allocation along with the speculative early release of physical registers. These renaming policies may cause a register operand not to be kept in the Physical Register File (PRF). Thus, we add a low-ported Auxiliary Register File (XRF) located outside the processor core that keeps the values absent in PRF and supplies them at higher latency. To support the location of register operands being either in PRF or XRF, we use virtual registers. We consider omission and release policies directed by hardware prediction. Namely, we will use a single Last-Use Predictor that directs both speculative omission and release. We call this mechanism SR-LUP (Speculative Renaming based on Last-Use Prediction). Two Last-Use predictor designs of incremental complexity and performance are analyzed. In a 256-RO...

• Type: Conference
• Year: 2007
• Where: IPPS
• Authors: Jesús Alastruey, Teresa Monreal, Víctor Viñals, Mateo Valero
• Keywords: Distributed And Parallel Computing, IPPS 2007, Physical Register, Speculative, Speculative Omission