The counterflow pipeline processor architecture

The counterflow pipeline processor architecture (CFPP) is a proposal for a family of microarchitectures for RISC processors. The architecture derives its name from its fundamental feature, namely that instructions and results flow in opposite directions within a pipeline and interact as they pass. The architecture seeks geometric regularity in processor chip layout, purely local control to avoid performance limitations of complex global pipeline stall signals, and simplicity that might lead to provably correct processor designs. Moreover, CFPP designs allow asynchronous implementations, in contrast to conventional pipeline designs where the synchronization required for operand forwarding makes asynchronous designs unattractive. This paper presents the CFPP architecture and a proposal for an asynchronous implementation. Detailed performance simulations of a complete processor design are not yet available.