1. A functional unit for supporting multithreading, the functional unit comprising: a plurality of input ports configured to receive opcodes and operands for a plurality of threads, wherein each of the plurality of input ports is configured to receive an opcode and an operand for a different thread; a plurality of operators configured to perform operations using the received operands; an operator selector configured to select, based on each opcode, an operator from among the plurality of operators to perform a specific operation using an operand from among the received operands; and a plurality of output ports configured to output operation results of operations for each thread.