eMIPS, A Dynamically Extensible Processor
Richard Neil Pittman, Nathaniel L. Lynch, Alessandro Forin, Neil Pittman · 2006
The eMIPS architecture can realize the performance benefits of application-specific hardware optimizations in a general-purpose, multi-user system environment using a dynamically extensible processor architecture. It allows multiple secure Extensions to load dynamically and to plug into the stages of a pipelined data path, thereby extending the core instruction set of the microprocessor. Extensions can also be used to realize on-chip peripherals and if area permits even multiple cores. The new functionality can be exploited by patching the binaries of the existing applications, without requiring any changes to the compilers. A working FPGA prototype and a flexible simulation system demonstrate speedups of 2x-3x on a set of applications that include games, realtime programs and the SPEC2000 integer benchmarks. eMIPS is the first realized workstation based entirely on a dynamically extensible processor that is safe for general purpose, multi-user applications. By exposing the individual stages of the data path, eMIPS allows optimizations not previously possible. This includes permitting safe and coherent accesses to memory from within an Extension, optimizing multi-branched blocks, and throwing precise and restartable exceptions from within an Extension. 1