Here are three questions for those persons (and there are more than a few of them) who believe that China's cost-advantage in producing the goods it exports is derived from "slave" labor.
First, what do you mean by "slave labor"? Work conditions harsher than those now common in America and Europe are not sufficient to signal "slave labor." Nor is very low pay. Slave labor, accurately understood, exists only when a human being is owned by another human being, and the owner forces his slave to work at tasks chosen by the owner, with the slave having no real say in the matter or ability to resist.
Second, do you really believe that slaves (as defined above) would be desirable operatives in manufacturing plants?
Third, if your answer to the second question is "yes" (or even "perhaps"), why was China a less-productive economy during Mao's reign? Why were the Chinese less successful then at exporting to the west than they are today?
Similar (but not identical) questions can be asked of persons who insist that China's success at exporting is due to that country's current repressiveness (if not practice of slavery).