Parallel condition-code generation for high-frequency PowerPC microprocessors

Abstract

Improving the speed and performance of microprocessors requires aggressive leveraging of the interplay of microarchitecture and circuit design. We describe a unique, high-frequency dataflow macro for accelerating conditional-branch resolution by computing condition codes in parallel with computing the corresponding arithmetic results. This macro improves the microarchitecture by reducing conditional-branch latency while achieving high speed through a pulse-mode, delayed-reset dynamic circuit implementation. The design has been realized in a 64-bit PowerPC integer processor that operates at 1.0 GHz (0.15 micron CMOS process).