Seeking the name of a science fiction novel

It should be Liu Cixin's. There was a primitive planet with some primitive civilization on it (it felt a little like Avatar), and then humans often went there with tourist groups and explorers. There seemed to be some sacred land ruins that could not be violated. There seemed to be a crystal-like memory. After a series of events, the truth was revealed that this planet was actually a giant computer left behind by an ancient civilization. It was used to calculate something in the universe, and every time it was activated, it consumed a huge amount of resources. After the last activation, the people on the planet had degenerated into a primitive state. Then, the computer would be activated again, and the universe would be destroyed again because of its calculations. Searching for such keywords could only find Chao Wen Dao, which obviously wasn't the case.