> I've never seen where the high level discussions were happening

Thanks for your interest. This is something we could improve on. We were supposed to document the JIT better in 3.15, but right now we're crunching for the 3.15 release. I'll try to get to updating the docs soon if there's enough interest. PEP 744 does not document the new frontend.

I wrote a somewhat high-level overview here in a previous blog post https://fidget-spinner.github.io/posts/faster-jit-plan.html#...

> does this mean each opcode is possibly split into two (or more?) stencils, with and without removed increfs/decrefs?

This is a great question, the answer is not exactly! The key is to expose the refcount ops in the intermediate representation (IR) as one single op. For example, BINARY_OP becomes BINARY_OP, POP_TOP (DECREF), POP_TOP (DECREF). That way, instead of optimizing for n operations, we just need to expose refcounting of n operations and optimize only 1 op (POP_TOP). Thus, we just need to refactor the IR to expose refcounting (which was the work I divided up among the community).

If you have any more questions, I'm happy to answer them either in public or email.