Lazy BTB: reduce BTB energy consumption using dynamic profiling

In this paper, we propose an alternative BTB design, called lazy BTB, to reduce the BTB energy consumption by filtering out the redundant lookups. The most distinct feature of the lazy BTB is that it dynamically profiles the taken traces during program execution. Unlike the traditional design in which the BTB has to be looked up every instruction fetch, by introducing an additional field to record the trace information, our design can achieve the goal of one BTB lookup per taken trace. The experimental results show that with a negligible performance degradation the lazy BTB can reduce the BTB energy consumption by about 77% on average for the MediaBench applications