I am being downvoted because people can't look past personal likes/dislikes and are conditioned to look uncritically at software that they like/depend on. Yet the obvious point I'm making here has nothing to do with the quality of LuaJIT as a tool that can solve problems. There are lots of examples of powerful, high-quality software that sits on an atrocious, impossible-to-understand codebase (e.g. pretty much anything by fabrice bellard, which ironically enough, some even consider as _good_ C) and while LuaJIT may not be at that level, it's not currently _good enough_.
I think we need to move past personality-worship and start striving for quality where it matters. Read this thread and you'll find numerous posts referring to Mike Pall as an alien/god-of-coding and so on. This is not at all helpful.
A software project that is positioned as something with staying power and a base for others to build on should be judged more on its ability to attract and maintain a community around it rather than its creator/profit that it generates/other superficial attributes. It is for this reason that a well-documented codebase that facilitates understanding is of _paramount importance_.
Please don't go on about downvotes as a rhetorical device. That's a variant of the complaining that the site guidelines ask us all not to do: https://news.ycombinator.com/newsguidelines.html.
LuaJIT is not a toy compiler from a textbook. There's a lot of inherent complexity in a production compiler that employs advanced optimizations and needs to work on various CPU architectures and operating systems. This reflects in the code.