CIRCLE WITH A DOT

@david_chisnall Re: second jobs. We increasingly struggle to get good candidates into politics. Surely the last thing we want to do is narrow the pool even further? For example, you'd have to be Sir-Humphrey-brave to stand in a byelection knowing that you have to give up your livelihood, perhaps for only a few months, and then perhaps be worse off than before you started. There are some jobs that are incompatible with being an MP. I don't think I want, say, a dentist to stop practising, though.

@david_chisnall A very early prototype of yk used LLVM for these purposes, but the compilation performance was awful (from memory something like 1000x worse than we needed). It's not really LLVM's fault though: we were feeding it an input it never expected to see. [We also encountered multiple threading bugs, but I imagine those have been fixed in the interim.]

@david_chisnall I assumed that LuaJIT did quite a good job with FFI performance (the API it defined has spread more widely), but I haven't benchmarked it! That said, there are some heuristics in LuaJIT that do not always play well with real-world code.

yklua will just do whatever PUC Lua does, but it will probably inline right up until the FFI call, which might help. That said, right now, you can still hit missing bits that tank performance in any yk interpreter, so it's difficult to say!

@llimllib Which browser? They work on my Android phone's browsers, but video compatibility beyond that is a bit of an unknown to me.

I want to say a big thanks to Shopify and the Royal Academy of Engineering who graciously funded this research. I'd like to dedicate this work to the late Chris Seaton, who was an early champion of yk: he is much missed by me and many others.

This isn't just a technique for Lua, though -- it works for any C interpreter compilable with LLVM! More about how and why in this new post 'Retrofitting JIT Compilers into C Interpreters' looking at our new 'yk' system. https://tratt.net/laurie/blog/2026/retrofitting_jit_compilers_into_c_interpreters.html

C interpreters underlie many of our most widely used language implementations -- but they're slow. Wouldn't it be great if we could turn them into JIT compiling VMs? This video shows what happens when we do just that to the normal Lua VM (first) and "yklua" (Lua w/JIT, second).