GH-124483: Treat _Py_Dealloc as an escaping call in tier two

[brandtbucher]

This fixes various issues related to finalizers "invalidating the world".

Despite the fact that it executes about 29 billion additional _CHECK_VALIDITY, _SET_IP, and _CHECK_VALIDITY_AND_SET_IP instructions on the benchmarks, these are some of our cheapest uops, so performance and memory are both unaffected.

• Issue: _Py_Dealloc is an escaping call #124483

[Fidget-Spinner]

I thought Mark was planning to fix this by deferring Py_DECREF finalizers to safepoints? Or did that get deferred too?

[brandtbucher]

I thought Mark was planning to fix this by deferring Py_DECREF finalizers to safepoints? Or did that get deferred too?

We may at some point, but this will keep things safe until then. We may also not defer all decrefs, depending on how disruptive it is to do so.

In any case, I'll wait until after #124392 is merged to pick this up and re-run the benchmarks, since this will introduce a lot of new spills.