@Override
    public boolean isCommonSubexpression(Instruction i) {
        if(i instanceof BinaryInstruction) {
            BinaryInstruction b = (BinaryInstruction)i;
            return this.getOpcode() == b.getOpcode()
                && this.arg1.equals(b.arg1)
                && this.arg2.equals(b.arg2);
        }
        return false;
    }