Grand unified tail-calling JIT

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Feature or enhancement

Proposal:

We have a tail calling interpreter. I now propose to tightly couple that with the JIT, so we can tail call into the JIT and tail call out of it.

This has a few benefits:

1. No more C stack consumption by the JIT.
2. Much more efficient entry and exit of jitted code. OSR entry is just a single indirect jump.

We need to align the calling convention of the JIT and the tail calling interpreter. This will need careful benchmarking to make sure we don't regress JIT performance.

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

Linked PRs

• gh-129819: Allow tier2/JIT and tailcall #129820

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cc @brandtbucher