Kind of surprised to see an article about TableGen hit #1 on HN. TableGen is pretty arcane. I had some dealings with it in about 2016 while creating a backend for compiler targeting a new processor architecture. It was very poorly documented then - mostly you looked at what other people had done with other architectures and tried to fit that into what was needed for your new architecture. Anyway, I guess I'd be surprised if even 1,000 people in the world needed to actually do much with TableGen.