gh-135228: Create __dict__ and __weakref__ descriptors for object

Include/internal/pycore_interp_structs.h

@@ -691,6 +691,13 @@ struct _Py_interp_cached_objects {
     PyTypeObject *paramspecargs_type;
     PyTypeObject *paramspeckwargs_type;
     PyTypeObject *constevaluator_type;
+
+    /* Descriptors for __dict__ and __weakref__ */
+#ifdef Py_GIL_DISABLED
+    PyMutex descriptor_mutex;
+#endif
+    PyObject *dict_descriptor;
+    PyObject *weakref_descriptor;
 };
 
 struct _Py_interp_static_objects {

Include/internal/pycore_typeobject.h

@@ -40,6 +40,7 @@ extern void _PyTypes_FiniTypes(PyInterpreterState *);
 extern void _PyTypes_FiniExtTypes(PyInterpreterState *interp);
 extern void _PyTypes_Fini(PyInterpreterState *);
 extern void _PyTypes_AfterFork(void);
+extern void _PyTypes_FiniCachedDescriptors(PyInterpreterState *);
 
 static inline PyObject **
 _PyStaticType_GET_WEAKREFS_LISTPTR(managed_static_type_state *state)

Lib/inspect.py

@@ -1698,7 +1698,8 @@ def _shadowed_dict_from_weakref_mro_tuple(*weakref_mro):
             class_dict = dunder_dict['__dict__']
             if not (type(class_dict) is types.GetSetDescriptorType and
                     class_dict.__name__ == "__dict__" and
-                    class_dict.__objclass__ is entry):
+                    (class_dict.__objclass__ is object or
+                     class_dict.__objclass__ is entry)):
                 return class_dict
     return _sentinel
 

Objects/descrobject.c

@@ -39,41 +39,41 @@ descr_name(PyDescrObject *descr)
 }
 
 static PyObject *
-descr_repr(PyDescrObject *descr, const char *format)
+descr_repr(PyDescrObject *descr, const char *kind)
 {
     PyObject *name = NULL;
     if (descr->d_name != NULL && PyUnicode_Check(descr->d_name))
         name = descr->d_name;
 
-    return PyUnicode_FromFormat(format, name, "?", descr->d_type->tp_name);
+    if (descr->d_type == &PyBaseObject_Type) {
+        return PyUnicode_FromFormat("<%s '%V'>", kind, name, "?");
+    }
+    return PyUnicode_FromFormat("<%s '%V' of '%s' objects>",
+                                kind, name, "?", descr->d_type->tp_name);
 }
 
 static PyObject *
 method_repr(PyObject *descr)
 {
-    return descr_repr((PyDescrObject *)descr,
-                      "<method '%V' of '%s' objects>");
+    return descr_repr((PyDescrObject *)descr, "method");
 }
 
 static PyObject *
 member_repr(PyObject *descr)
 {
-    return descr_repr((PyDescrObject *)descr,
-                      "<member '%V' of '%s' objects>");
+    return descr_repr((PyDescrObject *)descr, "member");
 }
 
 static PyObject *
 getset_repr(PyObject *descr)
 {
-    return descr_repr((PyDescrObject *)descr,
-                      "<attribute '%V' of '%s' objects>");
+    return descr_repr((PyDescrObject *)descr, "attribute");
 }
 
 static PyObject *
 wrapperdescr_repr(PyObject *descr)
 {
-    return descr_repr((PyDescrObject *)descr,
-                      "<slot wrapper '%V' of '%s' objects>");
+    return descr_repr((PyDescrObject *)descr, "slot wrapper");
 }
 
 static int

Objects/typeobject.c

@@ -4036,26 +4036,15 @@ subtype_getweakref(PyObject *obj, void *context)
     return Py_NewRef(result);
 }
 
-/* Three variants on the subtype_getsets list. */
-
-static PyGetSetDef subtype_getsets_full[] = {
-    {"__dict__", subtype_dict, subtype_setdict,
-     PyDoc_STR("dictionary for instance variables")},
-    {"__weakref__", subtype_getweakref, NULL,
-     PyDoc_STR("list of weak references to the object")},
-    {0}
-};
-
-static PyGetSetDef subtype_getsets_dict_only[] = {
-    {"__dict__", subtype_dict, subtype_setdict,
-     PyDoc_STR("dictionary for instance variables")},
-    {0}
+/* getset definitions for common descriptors */
+static PyGetSetDef subtype_getset_dict = {
+    "__dict__", subtype_dict, subtype_setdict,
+    PyDoc_STR("dictionary for instance variables"),
 };
 
-static PyGetSetDef subtype_getsets_weakref_only[] = {
-    {"__weakref__", subtype_getweakref, NULL,
-     PyDoc_STR("list of weak references to the object")},
-    {0}
+static PyGetSetDef subtype_getset_weakref = {
+    "__weakref__", subtype_getweakref, NULL,
+    PyDoc_STR("list of weak references to the object"),
 };
 
 static int
@@ -4591,10 +4580,36 @@ type_new_classmethod(PyObject *dict, PyObject *attr)
     return 0;
 }
 
+/* Add __dict__ or __weakref__ descriptor */
+static int
+type_add_common_descriptor(PyInterpreterState *interp,
+                           PyObject **cache,
+                           PyGetSetDef *getset_def,
+                           PyObject *dict)
+{
+#ifdef Py_GIL_DISABLED
+    PyMutex_Lock(&interp->cached_objects.descriptor_mutex);
+#endif
+    PyObject *descr = *cache;
+    if (!descr) {
+        descr = PyDescr_NewGetSet(&PyBaseObject_Type, getset_def);
+        *cache = descr;
+    }
+#ifdef Py_GIL_DISABLED
+    PyMutex_Unlock(&interp->cached_objects.descriptor_mutex);
+#endif
+    if (!descr) {
+        return -1;
+    }
+    if (PyDict_SetDefaultRef(dict, PyDescr_NAME(descr), descr, NULL) < 0) {
+        return -1;
+    }
+    return 0;
+}
 
 /* Add descriptors for custom slots from __slots__, or for __dict__ */
 static int
-type_new_descriptors(const type_new_ctx *ctx, PyTypeObject *type)
+type_new_descriptors(const type_new_ctx *ctx, PyTypeObject *type, PyObject *dict)
 {
     PyHeapTypeObject *et = (PyHeapTypeObject *)type;
     Py_ssize_t slotoffset = ctx->base->tp_basicsize;
@@ -4632,25 +4647,38 @@ type_new_descriptors(const type_new_ctx *ctx, PyTypeObject *type)
     type->tp_basicsize = slotoffset;
     type->tp_itemsize = ctx->base->tp_itemsize;
     type->tp_members = _PyHeapType_GET_MEMBERS(et);
+
+    PyInterpreterState *interp = _PyInterpreterState_GET();
+
+    if (type->tp_dictoffset) {
+        if (type_add_common_descriptor(
+            interp,
+            &interp->cached_objects.dict_descriptor,
+            &subtype_getset_dict,
+            dict) < 0)
+        {
+            return -1;
+        }
+    }
+    if (type->tp_weaklistoffset) {
+        if (type_add_common_descriptor(
+            interp,
+            &interp->cached_objects.weakref_descriptor,
+            &subtype_getset_weakref,
+            dict) < 0)
+        {
+            return -1;
+        }
+    }
+
     return 0;
 }
 
 
 static void
 type_new_set_slots(const type_new_ctx *ctx, PyTypeObject *type)
 {
-    if (type->tp_weaklistoffset && type->tp_dictoffset) {
-        type->tp_getset = subtype_getsets_full;
-    }
-    else if (type->tp_weaklistoffset && !type->tp_dictoffset) {
-        type->tp_getset = subtype_getsets_weakref_only;
-    }
-    else if (!type->tp_weaklistoffset && type->tp_dictoffset) {
-        type->tp_getset = subtype_getsets_dict_only;
-    }
-    else {
-        type->tp_getset = NULL;
-    }
+    type->tp_getset = NULL;
 
     /* Special case some slots */
     if (type->tp_dictoffset != 0 || ctx->nslot > 0) {
@@ -4755,7 +4783,7 @@ type_new_set_attrs(const type_new_ctx *ctx, PyTypeObject *type)
         return -1;
     }
 
-    if (type_new_descriptors(ctx, type) < 0) {
+    if (type_new_descriptors(ctx, type, dict) < 0) {
         return -1;
     }
 
@@ -6639,6 +6667,14 @@ _PyStaticType_FiniBuiltin(PyInterpreterState *interp, PyTypeObject *type)
 }
 
 
+void
+_PyTypes_FiniCachedDescriptors(PyInterpreterState *interp)
+{
+    Py_CLEAR(interp->cached_objects.dict_descriptor);
+    Py_CLEAR(interp->cached_objects.weakref_descriptor);
+}
+
+
 static void
 type_dealloc(PyObject *self)
 {

Python/pylifecycle.c

@@ -1906,6 +1906,7 @@ finalize_interp_clear(PyThreadState *tstate)
     _PyXI_Fini(tstate->interp);
     _PyExc_ClearExceptionGroupType(tstate->interp);
     _Py_clear_generic_types(tstate->interp);
+    _PyTypes_FiniCachedDescriptors(tstate->interp);
 
     /* Clear interpreter state and all thread states */
     _PyInterpreterState_Clear(tstate);

Tools/c-analyzer/cpython/_analyzer.py

@@ -67,6 +67,7 @@
     'PyMethodDef',
     'PyMethodDef[]',
     'PyMemberDef[]',
+    'PyGetSetDef',
     'PyGetSetDef[]',
     'PyNumberMethods',
     'PySequenceMethods',