According to embodiments of the invention, there is disclosed a data processing unit, a method of operating the same, computer program product and an instruction. In one embodiment according to the invention, there is provided a data processing unit for a computer processor, the data processing unit comprising a deep register access mechanism capable of performing a permutation operation on at least one data operand accessed from a register file of the computer processor, the permutation operation being performed in series with (i) register access for the data operand and (ii) execution of a data processing operation on the operand.