_Py_TryIncrefCompareStackRef incorrectly listed as non-escaping in cases generator

[Yhg1s]

Bug report

Bug description:

(This came up during the faster-cpython meeting, filing a bug so we don't forget.)

_Py_TryIncrefCompareStackRef and _Py_TryIncrefCompare are currently listed as non-escaping in the bytecode cases generator (

cpython/Tools/cases_generator/analyzer.py

Line 635 in 99ed302

"_Py_TryIncrefCompare",

), but they can in fact escape (in the DECREF path when we're no longer sure the object we INCREF'ed is a correct object, since it may have been a pointer to a new object in re-used memory). _Py_TryIncrefCompare isn't currently used in bytecodes.c, but _Py_TryIncrefCompareStackRef is used in LOAD_ATTR specializations, which are consequently incorrectly flagged as non-escaping (and also can also theoretically cause crashes because of the missing spilling).

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

[colesbury]

There are a lot of functions and macros in that list that are actually escaping, including: PyStackRef_CLEAR, PyStackRef_CLOSE, Py_CLEAR, (and other related functions), and _PyEval_FrameClearAndPop.

The list needs a thorough audit. For free threading specific issues, we should look for:

• Lock / critical section acquisitions within the function (e.g., PyException_GetTraceback)
• Py_DECREF and equivalent within the function (e.g., _Py_TryIncrefCompare)