Method, device and microprocessor for performing an xor clear without executing an xor instruction

Abstract

Improvements are made in how microprocessors execute logical exclusive OR instructions when the operands of this instruction are equal. XOR instructions with equal operands are used to clear registers and/or assign flags values without explicitly performing the actual XOR command. By setting or resetting these flags and/or clearing these registers directly, this mechanism allows these instructions to be paired with following dependent instructions simply by zeroing the dependent input of the following instructions. An architecture that hardwires the implementation into the microprocessor through logic gates is preferred. This will result in increased speed while reducing power consumption. Further, a full-sized ALU is not needed in order to execute the XOR instruction with equal operands. As this is a more direct procedure, a pipeline with a reduced capability ALU can be utilized.