AISC: Approximate Instruction Set Computer

Abstract

This paper makes the case for a single-ISA heterogeneous computing platform, AISC, where each compute engine (be it a core or an accelerator) supports a different subset of the very same ISA. An ISA subset may not be functionally complete, but the union of the (per compute engine) subsets renders a functionally complete, platform-wide single ISA. Tailoring the microarchitecture of each compute engine to the subset of the ISA that it supports can easily reduce hardware complexity. At the same time, the energy efficiency of computing can improve by exploiting algorithmic noise tolerance: by mapping code sequences that can tolerate (any potential inaccuracy induced by) the incomplete ISA-subsets to the corresponding compute engines.