Fix for types with no dict

Fidget-Spinner · Fidget-Spinner · commit d27e3888bded · 2021-08-16T22:27:42.000+08:00
diff --git a/Python/ceval.c b/Python/ceval.c
@@ -4409,11 +4409,14 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
             PyTypeObject *cls_type = Py_TYPE(cls);
             assert(cls_type->tp_dictoffset > 0);
             PyObject *dict = *(PyObject **) ((char *)cls + cls_type->tp_dictoffset);
-            DEOPT_IF(((PyDictObject *)dict)->ma_keys->dk_version !=
+            // Don't care if no dict -- tp_version_tag should catch anything wrong.
+            DEOPT_IF(dict != NULL && ((PyDictObject *)dict)->ma_keys->dk_version !=
                 cache1->dk_version_or_hint, LOAD_METHOD);
             DEOPT_IF(((PyTypeObject *)cls)->tp_version_tag != cache1->tp_version,
                 LOAD_METHOD);
-            
+            assert(cache1->dk_version_or_hint != 0);
+            assert(cache1->tp_version != 0);
+
             STAT_INC(LOAD_METHOD, hit);
             record_cache_hit(cache0);
             PyObject *res = cache2->obj;
diff --git a/Python/specialize.c b/Python/specialize.c
@@ -857,18 +857,17 @@ _Py_Specialize_LoadMethod(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name,
         SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_OUT_OF_RANGE);
         goto fail;
     }
-    // Technically this is fine for bound method calls, but slightly slower at
-    // runtime to get dict. TODO: profile pyperformance and see if it's worth it
-    // to slightly slow down the common case, so that we can specialize this
-    // uncommon one.
+    // Technically this is fine for bound method calls, but it's uncommon and
+    // slightly slower at runtime to get dict.
     if (owner_cls->tp_dictoffset < 0) {
         SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_NEGATIVE_DICTOFFSET);
         goto fail;
     }
     PyObject **owner_dictptr = _PyObject_GetDictPtr(owner);
     int owner_has_dict = (owner_dictptr != NULL && *owner_dictptr != NULL);
     owner_dict = owner_has_dict ? (PyDictObject *)*owner_dictptr : NULL;
-    Py_XINCREF(owner_dict); // make sure dict doesn't disappear halfway
+    // Make sure dict doesn't get GC-ed halfway.
+    Py_XINCREF(owner_dict);
     // Check for classmethods.
     int owner_is_class = PyType_Check(owner);
     owner_cls = owner_is_class ? (PyTypeObject *)owner : owner_cls;
