// For 2, we need to ensure that if there might be partial overlap,
		// then we can't use OpMove; we must use memmove instead.
		// (memmove handles partial overlap by copying in the correct
		// direction. OpMove does not.)
		//
		// Note that we have to be careful here not to introduce a call when
		// we're marshaling arguments to a call or unmarshaling results from a call.