A data processing system and method are disclosed. The system comprises an instruction-fetch stage where an instruction is fetched and a specific instruction is input into decode stage; a decode stage where said specific instruction indicates that contents of a register in a register file are used as an index, and then, the register file pointed to by said index is accessed based on said index; an execution stage where an access result of said decode stage is received, and computations are implemented according to the access result of the decode stage.