dispatching original instructions into an instruction buffer, the original instructions including at least one operand;

renaming the at least one operand;

selecting the original instructions from the instruction buffer;

sending selected instructions with explicit bits, which comprise values stored in a mapper table for each of a plurality of physical registers, to an internal operation code exchange table, which includes replacement rules for replacing the selected instructions with a simplified instruction based on the original instructions and the explicit bits;

replacing the selected instructions with the simplified instruction in accordance with the explicit bits; and

issuing the simplified instructions indirectly to an execution unit by sending the simplified instruction and all explicit bits for the operands to a content addressable memory address logic of the internal operation code exchange table, wherein if a bitvector, consisting of the original instruction and the explicit bits, matches a pattern stored in the internal operation code exchange table, the original instruction is replaced by the simplified instruction.