The Python recursion checks work as before.

In addition there is a separate counter for C stack checking which works as follows:

• There is a fixed limit of 3000 "points".
• "Normal" C calls that call Py_CheckRecursiveCall() use 1 point.
• Calls to PyObject_Repr use 2 points as they seem to use a bit more stack than most functions.
• Calls to _PyEval_EvalFrameDefault use 3 points, as it is a big function and keeps the limit in line with the original limit of 1000
• The ad-hoc recursion checks in the compiler are replaced with calls to Py_CheckRecursiveCall()

I intend to add PRs to perform real stack checks for the major platforms, but this seems to offer a reasonable approximation for other platforms.

• Issue: Implement stack overflow protection for supported platforms #91079