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[3.13] gh-132070: Use _PyObject_IsUniquelyReferenced in unicodeobject (gh-133039) #133126

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Merged
merged 2 commits into from
Apr 29, 2025
Merged

[3.13] gh-132070: Use _PyObject_IsUniquelyReferenced in unicodeobject (gh-133039) #133126

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gh-132070: Use _PyObject_IsUniquelyReferenced in unicodeobject (gh-13…
corona10 Apr 29, 2025
143bba0
Add _PyObject_IsUniquelyReferenced
corona10 Apr 29, 2025
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17 changes: 17 additions & 0 deletions Include/internal/pycore_object.h
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Original file line number Diff line number Diff line change
Expand Up @@ -165,6 +165,23 @@ static inline void _Py_RefcntAdd(PyObject* op, Py_ssize_t n)
extern void _Py_SetImmortal(PyObject *op);
extern void _Py_SetImmortalUntracked(PyObject *op);

// Checks if an object has a single, unique reference. If the caller holds a
// unique reference, it may be able to safely modify the object in-place.
static inline int
_PyObject_IsUniquelyReferenced(PyObject *ob)
{
#if !defined(Py_GIL_DISABLED)
return Py_REFCNT(ob) == 1;
#else
// NOTE: the entire ob_ref_shared field must be zero, including flags, to
// ensure that other threads cannot concurrently create new references to
// this object.
return (_Py_IsOwnedByCurrentThread(ob) &&
_Py_atomic_load_uint32_relaxed(&ob->ob_ref_local) == 1 &&
_Py_atomic_load_ssize_relaxed(&ob->ob_ref_shared) == 0);
#endif
}

// Makes an immortal object mortal again with the specified refcnt. Should only
// be used during runtime finalization.
static inline void _Py_SetMortal(PyObject *op, Py_ssize_t refcnt)
Expand Down
43 changes: 25 additions & 18 deletions Objects/unicodeobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1121,6 +1121,21 @@ unicode_fill_invalid(PyObject *unicode, Py_ssize_t old_length)
}
#endif

static PyObject*
resize_copy(PyObject *unicode, Py_ssize_t length)
{
Py_ssize_t copy_length;
PyObject *copy;

copy = PyUnicode_New(length, PyUnicode_MAX_CHAR_VALUE(unicode));
if (copy == NULL)
return NULL;

copy_length = Py_MIN(length, PyUnicode_GET_LENGTH(unicode));
_PyUnicode_FastCopyCharacters(copy, 0, unicode, 0, copy_length);
return copy;
}

static PyObject*
resize_compact(PyObject *unicode, Py_ssize_t length)
{
Expand All @@ -1132,7 +1147,14 @@ resize_compact(PyObject *unicode, Py_ssize_t length)
Py_ssize_t old_length = _PyUnicode_LENGTH(unicode);
#endif

assert(unicode_modifiable(unicode));
if (!unicode_modifiable(unicode)) {
PyObject *copy = resize_copy(unicode, length);
if (copy == NULL) {
return NULL;
}
Py_DECREF(unicode);
return copy;
}
assert(PyUnicode_IS_COMPACT(unicode));

char_size = PyUnicode_KIND(unicode);
Expand Down Expand Up @@ -1232,21 +1254,6 @@ resize_inplace(PyObject *unicode, Py_ssize_t length)
return 0;
}

static PyObject*
resize_copy(PyObject *unicode, Py_ssize_t length)
{
Py_ssize_t copy_length;
PyObject *copy;

copy = PyUnicode_New(length, PyUnicode_MAX_CHAR_VALUE(unicode));
if (copy == NULL)
return NULL;

copy_length = Py_MIN(length, PyUnicode_GET_LENGTH(unicode));
_PyUnicode_FastCopyCharacters(copy, 0, unicode, 0, copy_length);
return copy;
}

static const char*
unicode_kind_name(PyObject *unicode)
{
Expand Down Expand Up @@ -1836,7 +1843,7 @@ static int
unicode_modifiable(PyObject *unicode)
{
assert(_PyUnicode_CHECK(unicode));
if (Py_REFCNT(unicode) != 1)
if (!_PyObject_IsUniquelyReferenced(unicode))
return 0;
if (PyUnicode_HASH(unicode) != -1)
return 0;
Expand Down Expand Up @@ -14025,7 +14032,7 @@ _PyUnicode_FormatLong(PyObject *val, int alt, int prec, int type)
assert(PyUnicode_IS_ASCII(result));

/* To modify the string in-place, there can only be one reference. */
if (Py_REFCNT(result) != 1) {
if (!_PyObject_IsUniquelyReferenced(result)) {
Py_DECREF(result);
PyErr_BadInternalCall();
return NULL;
Expand Down
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