Power saving methods and apparatus to selectively enable comparators in a CAM renaming register file based on known processor state

摘要

A renaming register file complex for saving power is described. A mapping unit transforms an instruction register number (IRN) to a logical register number (LRN). The renaming register file maps an LRN to a physical register number (PRN), there being a greater number of physical registers than addressable by direct use of the IRN. The renaming register file uses a content addressable memory (CAM) to provide the mapping function. The renaming register file CAM further uses current processor state information to selectively enable tag comparators to minimize power in accessing registers. When a tag comparator is not enabled it remains in a low power state. A processor using a renaming register file with low power features is also described.