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gh-130706: Add a fast path to _Py_Dealloc() for non-GC objects. #158645

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gh-130706: Add a fast path to _Py_Dealloc() for non-GC objects. #158645

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gh-130706: Add a fast path to _Py_Dealloc() for non-GC objects.
corona10 Oct 3, 2026
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corona10 Oct 3, 2026
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corona10 Oct 4, 2026
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-10-03-19-11-03.gh-issue-130706.01-O6U.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Add a fast path to ``_Py_Dealloc()`` for non-GC objects. Patch by Donghee
Na.
26 changes: 24 additions & 2 deletions Objects/object.c
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Expand Up @@ -3306,8 +3306,8 @@ next" object in the chain to 0. This can easily lead to stack overflows.
To avoid that, if the C stack is nearing its limit, instead of calling
dealloc on the object, it is added to a queue to be freed later when the
stack is shallower */
void
_Py_Dealloc(PyObject *op)
static Py_NO_INLINE void
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py_dealloc(PyObject *op)
{
PyTypeObject *type = Py_TYPE(op);
unsigned long gc_flag = type->tp_flags & Py_TPFLAGS_HAVE_GC;
Expand Down Expand Up @@ -3372,6 +3372,28 @@ _Py_Dealloc(PyObject *op)
}
}

/*
* gh-130706: Keep the GC/reftracer path in the non-inlined py_dealloc().
* Inlining it makes the compiler save callee-saved registers at entry,
* so the non-GC objects path would have unnecessary register spills.
*/
void
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_Py_Dealloc(PyObject *op)
{
#if !defined(Py_DEBUG) && !defined(Py_TRACE_REFS)
// gh-130706: Avoid unnecessary register spills for non-GC objects.
PyTypeObject *type = Py_TYPE(op);
if (_PyRuntime.ref_tracer.tracer_func == NULL
&& !(type->tp_flags & Py_TPFLAGS_HAVE_GC))
{
type->tp_dealloc(op);
return;
}
#endif
// GC objects (trashcan), reftracer set, or debug builds.
py_dealloc(op);
}


PyObject **
PyObject_GET_WEAKREFS_LISTPTR(PyObject *op)
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