A technique for flattening architectural register windows into flattened space depending on a current window pointer to a register window is provided. The technique involves converting an n-bit value of a particular register in a register window to an x-bit value dependent on the current window pointer, where x is greater than n, and where the x-bit value is used for register dependency checking among a plurality of instructions.
The present apparatus reduces hardware resources and improves data read throughput in an information processing apparatus employing the out-of-order instruction execution method. The apparatus includes: an arithmetic operation unit which executes a window switching instruction and an instruction relating to data stored in the current register or data held in the replacing buffer; and a control unit which transfers, if a window switching instruction is decoded at execution of the window switching instruction by the arithmetic operation unit, data of the register window which is to be specified by the current window pointer upon completion of execution of the window switching instruction, to the replacing buffer.
