6.6.8.8.2 NaN Propagation Result Write

NaN operand values are detected in the RD-stage, prioritized, and then passed (via an Instruction/Hazard Tracker FIFO entry) to the instruction WB-stage. A valid NaN propagation will cause the operation result from the Execute stage to be ignored, and the propagated NaN value to be written into the result destination instead, as discussed in NaN Propagation.