Abstract: A processor or processor core has register file circuitry having a plurality of physical registers and a plurality of tag storing portions corresponding respectively to the physical registers. Each tag storing portion stores a tag representing a logical register ID allocated to the corresponding physical register. A register selection unit receives a logical register ID and selects one of the logical registers whose tag matches the received logical register ID. A tag changing unit changes the stored tags so as to change a mapping between at least one logical register ID and one of the physical registers. Such register circuitry permits a mapping between logical register IDs and physical registers to be changed quickly efficiently and can permit a desired physical register to be selected quickly.

Abstract: Register file circuitry, for use in a processor or processor core, comprises a plurality of physical registers (320-32D-1) and a plurality of tag storing portions (340-34D-1) corresponding respectively to the physical registers. Each tag storing portion stores a tag representing a logical register ID allocated to the corresponding physical registers.