@Override
	protected void doExecute() {
        //if those two factories are both null value
		//direct push true or false
		MethodVisitor mv = getInstructions().getMv();
		if(isNullValue(leftFactor) && isNullValue(rightFactor)){
			if(Operator.EQUAL_TO.equals(getOperatorSymbol())){
				//push true to stack
		        mv.visitInsn(Opcodes.ICONST_0 + 1);
		        block.getMethod().getStack().push(Type.INT_TYPE);
		        return;
			}else if(Operator.NOT_EQUAL_TO.equals(getOperatorSymbol())){
				//push false to stack
		        mv.visitInsn(Opcodes.ICONST_0);
		        block.getMethod().getStack().push(Type.INT_TYPE);
		        return;
			}
		}else if(isNullValue(leftFactor) || isNullValue(rightFactor)){
			instructionGenerate();
	        block.getMethod().getStack().pop();
	        block.getMethod().getStack().push(Type.INT_TYPE);
		}else{
			super.doExecute();
		}
	}