SIMP (Single Instruction stream/Multiple instruction Pipelining): a novel high-speed single-processor architecture

Abstract

SIMP is a novel multiple instruction-pipeline parallel architecture. It is targeted for enhancing the performance of SISD processors drastically by exploiting both temporal and spatial parallelisms, and for keeping program compatibility as well. Degree of performance enhancement achieved by SIMP depends on; i) how to supply multiple instructions continuously, and ii) how to resolve data and control dependencies effectively. We have devised the outstanding techniques for instruction fetch and dependency resolution. The instruction fetch mechanism employs unique schemes of; i) prefetching multiple instructions with the help of branch prediction, ii) squashing instructions selectively, and iii) providing multiple conditional modes as a result. The dependency resolution mechanism permits out-of-order execution of sequential instruction stream. Our out-of-order execution model is based on Tomasulo's algorithm which has been used in single instruction-pipeline processors. However, it is greatly extended and accommodated to multiple instruction pipelining with; i) detecting and identifying multiple dependencies simultaneously, ii) alleviating the effects of control dependencies with both eager execution and advance execution, and iii) ensuring a precise machine state against branches and interrupts. By taking advantage of these techniques, SIMP is one of the most promising architectures toward the coming generation of high-speed single processors.