Performance Improvement with Circuit-Level Speculation

Current superscalar microprocessors' performance depends on its frequency and the number of useful instructions that can be processed per cycle (IPC). In this paper we propose a method called approximation to reduce the logic delay of a pipe-stage. The basic idea of approximation is to implement the logic function partially instead of fully. Most of the time the partial implementation gives the correct result as if the function is implemented fully but with fewer gates delay allowing a higher pipeline frequency. We apply this method on three logic blocks. Simulation results show that this method provides some performance improvement for a wide-issue superscalar if these stages are finely pipelined