`_Py_RefcntAdd` doesn't increment ref count stats

[EdNutting]

Bug report

Bug description:

Hi,

I am unsure if this intentional or not so apologies if this turns out not to be a bug.

The code for _Py_RefcntAdd does not include _Py_INCREF_STAT_INC. This appears to mean the statistics do not track these additions to the reference count, which are increments (although not increments by 1, they are increasing the ref count in a single operation).

cpython/Include/internal/pycore_object.h

Line 121 in ad9d059

static inline void _Py_RefcntAdd(PyObject* op, Py_ssize_t n)

I believe this may be an oversight because this stat should be tracked, and also because the corresponding decrement ref count code does call _Py_DECREF_STAT_INC (e.g.

cpython/Include/internal/pycore_object.h

Line 383 in ad9d059

_Py_DECREF_STAT_INC();

)

I have checked the callers of _Py_RefcntAdd (in listobject.c and tupleobject.c) and they do not separately perform the stats tracking.

Is this an issue or is there a reason this ref count increment is excluded?

Thanks,
Ed

CPython versions tested on:

3.12, 3.13

Operating systems tested on:

Linux, macOS

Linked PRs

• gh-127599: Fix _Py_RefcntAdd missing calls to _Py_INCREF_STAT_INC/_Py_INCREF_IMMORTAL_STAT_INC #127717
• [3.13] gh-127599: Fix _Py_RefcntAdd missing calls to _Py_INCREF_STAT_INC/_Py_INCREF_IMMORTAL_STAT_INC (GH-127717) #127963
• [3.12] gh-127599: Fix _Py_RefcntAdd missing calls to _Py_INCREF_STAT_INC/_Py_INCREF_IMMORTAL_STAT_INC (GH-127717) #128712
• [3.13] gh-127599: Fix _Py_RefcntAdd missing calls to _Py_INCREF_STAT_INC/_Py_INCREF_IMMORTAL_STAT_INC (GH-127717) #128713

[ZeroIntensity]

Looks like a bug. We're missing _Py_INCREF_IMMORTAL_STAT_INC for immortal objects as well.

[EdNutting]

Thank you for such a quick reply! I'll try to clone CPython separately to create a PR to fix these over the next few days.