The floating point unit in the synergistic processor element of a CELL processor is a fully-pipelined 4-way SIMD unit designed to accelerate media and data streaming. It supports 32-bit single-precision floating point and 16-bit integer operands with two different latencies, optimizing the performance of critical single-precision multiply-add operations. It employs fine-grained clock gating for power saving. Architecture, logic, circuits and integration are co-designed to meet the performance, power, and area goals.

The floating-point unit in the synergistic processor element of the 1st generation multi-core CELL processor is described. The FPU supports 4-way SIMD single precision and integer operations and 2-way SIMD double precision operations. The design required a high-frequency, low latency, power and area efficiency with primary application to the multimedia streaming workloads, such as 3D graphics. The FPU has 3 different latencies, optimizing the performance critical single precision FMA operations, which are executed with a 6-cycle latency at an 11FO4 cycle time. The latency includes the global forwarding of the result. These challenging performance, power, and area goals were achieved through the co-design of architecture and implementation with optimizations at all levels of the design. This paper focuses on the logical and algorithmic aspects of the FPU we developed, to achieve these goals.