Exploiting register-usage for saving register-file energy in embedded processors

Low power register file design plays an important role in an embedded processor. In this paper, we exploit register-usage in a program to find out unused registers, and turn these unused registers into low power mode by annotating power-controlling instructions. The whole work is performed by applying the hardware/software co-design principle. For the hardware part, we propose a voltage-scaling control logic to supply voltages for each register. For the software part, we propose a power-controlling-code annotation approach to determine the voltage scaling behavior for each register. Simulation results show that the proposed approach outperforms the other related approaches in terms of the energy-delay product.