Thanks, sljit looks somewhat similar to GNU lightning.

On reflection I wonder if I overstated the widespread use of JIT and of JIT compiler frameworks. All the 'major' well-resourced high-profile JIT-based interpreters I can think of don't use an off-the-shelf JIT framework for their backend, which makes sense as they want to carefully tune the code-generation. OpenJDK, OpenJ9, .Net, V8, SpiderMonkey, JavaScriptCore. LuaJIT and Python's new JIT don't use one either, nor does the Linux kernel's BPF engine.

The Guile Scheme interpreter uses a fork of the GNU Lightning JIT library. [0] Julia and (as mentioned) Postgres use LLVM for their JITs. I'm trying to think of other projects that use a JIT framework/library.

Similarly, I can't think of many problem domains where it makes sense to use JIT. The ones that spring to mind are interpreters (of course), regex engines, and DBMSs. JIT can also help in high-performance computing, to tailor the code to the particular problem and the particular CPU. [1] I don't think there are many other contexts where it makes sense to use JIT though.

JIT compilation brings its own drawbacks in portability (both between hardware platforms and operating systems), complexity, and perhaps cybersecurity, which might also limit its adoption, even if a good JIT framework could help with all three.

[0] https://doc.guix.gnu.org/guile/latest/en/html_node/Just_002d...

[1] https://www.intel.com/content/www/us/en/developer/articles/t...