Revert "Prebuild mro_dict for find_name_in_mro"

This reverts commit 56d13fc.

Author: sergey-miryanov

Objects/typeobject.c

@@ -5636,26 +5636,6 @@ find_name_in_mro(PyTypeObject *type, PyObject *name, int *error)
     return res;
 }
 
-static PyObject *
-find_name_in_mro_new(PyObject *mro_dict, PyObject *name, int *error)
-{
-    ASSERT_TYPE_LOCK_HELD();
-
-    Py_hash_t hash = _PyObject_HashFast(name);
-    if (hash == -1) {
-        *error = -1;
-        return NULL;
-    }
-
-    PyObject *res = NULL;
-    if (_PyDict_GetItemRef_KnownHash((PyDictObject *)mro_dict, name, hash, &res) < 0) {
-        *error = -1;
-    } else {
-        *error = 0;
-    }
-    return res;
-}
-
 /* Check if the "readied" PyUnicode name
    is a double-underscore special name. */
 static int
@@ -11065,7 +11045,7 @@ slotptr(PyTypeObject *type, int ioffset)
  * because that's convenient for fixup_slot_dispatchers(). This function never
  * sets an exception: if an internal error happens (unlikely), it's ignored. */
 static pytype_slotdef *
-update_one_slot(PyTypeObject *type, pytype_slotdef *p, PyObject *mro_dict)
+update_one_slot(PyTypeObject *type, pytype_slotdef *p)
 {
     ASSERT_TYPE_LOCK_HELD();
 
@@ -11096,11 +11076,7 @@ update_one_slot(PyTypeObject *type, pytype_slotdef *p, PyObject *mro_dict)
     assert(!PyErr_Occurred());
     do {
         /* Use faster uncached lookup as we won't get any cache hits during type setup. */
-        if (mro_dict == NULL) {
-            descr = find_name_in_mro(type, p->name_strobj, &error);
-        } else {
-            descr = find_name_in_mro_new(mro_dict, p->name_strobj, &error);
-        }
+        descr = find_name_in_mro(type, p->name_strobj, &error);
         if (descr == NULL) {
             if (error == -1) {
                 /* It is unlikely but not impossible that there has been an exception
@@ -11194,7 +11170,7 @@ update_slots_callback(PyTypeObject *type, void *data)
 
     pytype_slotdef **pp = (pytype_slotdef **)data;
     for (; *pp; pp++) {
-        update_one_slot(type, *pp, NULL);
+        update_one_slot(type, *pp);
     }
     return 0;
 }
@@ -11247,38 +11223,11 @@ fixup_slot_dispatchers(PyTypeObject *type)
     // where we'd like to assert that the type is locked.
     BEGIN_TYPE_LOCK();
 
-    PyObject *mro = lookup_tp_mro(type);
-    assert(mro);
-
-    PyObject *mro_dict = NULL;
-    Py_ssize_t n = PyTuple_GET_SIZE(mro);
-    for (Py_ssize_t i = 0; i < n; i++) {
-        PyObject *base = PyTuple_GET_ITEM(mro, n-i-1);
-        PyObject *dict = lookup_tp_dict(_PyType_CAST(base));
-        assert(dict && PyDict_Check(dict));
-
-        if (i == 0) {
-            mro_dict = PyDict_Copy(dict);
-            if (!mro_dict) {
-                PyErr_Clear();
-                break;
-            }
-        } else {
-            if (PyDict_Merge(mro_dict, dict, 1) < 0) {
-                Py_CLEAR(mro_dict);
-                PyErr_Clear();
-                break;
-            }
-        }
-    }
-
     assert(!PyErr_Occurred());
     for (pytype_slotdef *p = slotdefs; p->name; ) {
-        p = update_one_slot(type, p, mro_dict);
+        p = update_one_slot(type, p);
     }
 
-    Py_XDECREF(mro_dict);
-
     END_TYPE_LOCK();
 }