Patent ID: 6260136
Filing Date: 2001-07-10
Classification: G06F

Abstract:
A data processor comprising:a register file having a plurality of general-purpose registers each for storing data;a plurality of operational units each for exchanging data with said register file and performing an operation designated by an instruction corresponding thereto;a substitute register for storing data representing the result of the operation performed by a specific one of said plurality of operational units in place of any of said plurality of general-purpose registers; anda controller for controlling the writing of data in said register file, the reading of data stored in said register file, the writing of data in said substitute register, and the reading of data stored in said substitute register, said controller having a tag register for storing a tag indicative of which one of said plurality of general purpose registers is substituted by said substitute register,wherein said controller further has a flag register for storing a flag indicative of whether data stored in said substitute register is effective or ineffective, andwhen an instruction designating the operation to be performed by said specific operational unit is given, said instruction being accompanied by a write address for specifying which one of said plurality of general-purpose registers should store the result of said designated operation, and the flag of said flag register indicates ineffectiveness,controlling said substitute register such that data representing the result of the operation performed by said specific operational unit is written therein;updating the flag of said flag register such that effectiveness is indicated thereby; andupdating the tag of said tag register such that said write address is indicated thereby.