I highly recommend the blog posts if you're into learning how languages are implemented, by the way. They're incredible deep dives, but he uses the details-element to keep the metaphorical descents into Mariana Trench optional so it doesn't get too overwhelming.
I even had the privilege of congratulating him the 1000th star of the GH repo[3], where he reassured me and others that he's still working on it despite the long pause after the last blog post, and that this mainly has to do with behind-the-scenes rewrites that make no sense to publish in part.
[0] https://arxiv.org/abs/2011.13127
[1] https://sillycross.github.io/2022/11/22/2022-11-22/
[2] https://sillycross.github.io/2023/05/12/2023-05-12/
[3] https://github.com/luajit-remake/luajit-remake/issues/11