1. A method of migrating data to a register file cache, the method comprising: receiving at a migration unit a register read operation to be executed by a particular functional unit of a plurality of functional units, the register read operation specifying a particular physical register of a plurality of physical registers to be read; querying a register file cache associated with the particular functional unit to determine if the register file cache currently comprises data for the particular physical register; and in response to determining the register file cache associated with the particular functional unit does not currently comprise data for the particular physical register, migrating data to the register file cache associated with the particular functional unit.