Compiling for energy efficiency on timing speculative processors

Abstract

Timing speculation is a promising technique for improving microprocessor yield, in field reliability, and energy efficiency. Previous evaluations of the energy efficiency benefits of timing speculation have either been based on code compiled for a traditional target [2] — a processor that produces no errors, or code that relies on additional hardware support [6]. In this paper, we advocate that binaries for timing speculative processors should be optimized differently than those for conventional processors to maximize the energy benefits of timing speculation. Since the program binary determines the utilization pattern of the processor, which in turn influences the error rate of the processor and the energy efficiency of timing speculation, binary optimizations for timing speculative processors should attempt to manipulate the utilization of different microarchitectural units based on their likelihood of causing errors. An exploration of targeted and standard compiler optimizations demonstrates that significant energy benefits are possible from TS-aware binary optimization.