Speculative pre-execution assisted by compiler (SPEAR)

Speculative pre-execution achieves efficient data prefetching by running additional prefetching threads on spare hardware contexts. Various implementations for speculative pre-execution have been proposed, including compiler-based static approaches and hardware-based dynamic approaches. A static approach defines the p-thread at compile time and executes it as a stand-alone running thread. Therefore, it cannot efficiently take dynamic events into account and requires a higher fetch bandwidth. Conversely, a hardware approach is, by essence, able to dynamically make use run-time information. However, it requires more complex hardware and also lacks global information on data and control flow. This paper proposes Speculative Pre-Execution Assisted by compileR (SPEAR), a pre-execution model which is a hybrid of the two approaches. It relies on a post-compiler to extract the p-thread code from program binaries and uses custom- designed hardware to execute the p-thread.