Remove TYPE_CHANGED

Always use the type version from the __getattribute__ lookup (even if
its zero). The guard will fail if the type changes afterwards.

Author: mpage

Python/specialize.c

@@ -548,7 +548,6 @@ _PyCode_Quicken(_Py_CODEUNIT *instructions, Py_ssize_t size, PyObject *consts,
 #define SPEC_FAIL_ATTR_METACLASS_OVERRIDDEN 34
 #define SPEC_FAIL_ATTR_SPLIT_DICT 35
 #define SPEC_FAIL_ATTR_DESCR_NOT_DEFERRED 36
-#define SPEC_FAIL_ATTR_TYPE_CHANGED 37
 
 /* Binary subscr and store subscr */
 
@@ -837,7 +836,6 @@ typedef enum {
     DUNDER_CLASS, /* __class__ attribute */
     GETSET_OVERRIDDEN, /* __getattribute__ or __setattr__ has been overridden */
     GETATTRIBUTE_IS_PYTHON_FUNCTION,  /* Descriptor requires calling a Python __getattribute__ */
-    TYPE_CHANGED,  /* Error: the type changed during classification */
 } DescriptorClassification;
 
 
@@ -887,8 +885,8 @@ static DescriptorClassification
 analyze_descriptor(PyTypeObject *type, PyObject *name, PyObject **descr, unsigned int *tp_version, int store)
 {
     bool has_getattr = false;
-    bool have_getattribute_ver = false;
-    unsigned int getattribute_ver;
+    bool have_ga_version = false;
+    unsigned int ga_version;
     if (store) {
         if (type->tp_setattro != PyObject_GenericSetAttr) {
             *descr = NULL;
@@ -906,26 +904,20 @@ analyze_descriptor(PyTypeObject *type, PyObject *name, PyObject **descr, unsigne
             /* One or both of __getattribute__ or __getattr__ may have been
              overridden See typeobject.c for why these functions are special. */
             PyObject *getattribute = _PyType_LookupRefAndVersion(type,
-                &_Py_ID(__getattribute__), &getattribute_ver);
-            have_getattribute_ver = true;
+                &_Py_ID(__getattribute__), &ga_version);
+            have_ga_version = true;
             PyInterpreterState *interp = _PyInterpreterState_GET();
             bool has_custom_getattribute = getattribute != NULL &&
                 getattribute != interp->callable_cache.object__getattribute__;
-            unsigned int getattr_ver;
-            PyObject *getattr = _PyType_LookupRefAndVersion(type, &_Py_ID(__getattr__), &getattr_ver);
+            PyObject *getattr = _PyType_LookupRef(type, &_Py_ID(__getattr__));
             has_getattr = getattr != NULL;
-            if (getattr_ver != getattribute_ver) {
-                Py_XDECREF(getattribute);
-                Py_XDECREF(getattr);
-                return TYPE_CHANGED;
-            }
             if (has_custom_getattribute) {
                 if (getattro_slot == _Py_slot_tp_getattro &&
                     !has_getattr &&
                     Py_IS_TYPE(getattribute, &PyFunction_Type)) {
                     *descr = getattribute;
                     assert(getattr == NULL);
-                    *tp_version = getattribute_ver;
+                    *tp_version = ga_version;
                     return GETATTRIBUTE_IS_PYTHON_FUNCTION;
                 }
                 /* Potentially both __getattr__ and __getattribute__ are set.
@@ -952,12 +944,8 @@ analyze_descriptor(PyTypeObject *type, PyObject *name, PyObject **descr, unsigne
     }
     unsigned int descr_version;
     PyObject *descriptor = _PyType_LookupRefAndVersion(type, name, &descr_version);
-    if (have_getattribute_ver && (descr_version != getattribute_ver)) {
-        Py_XDECREF(descriptor);
-        return TYPE_CHANGED;
-    }
     *descr = descriptor;
-    *tp_version = descr_version;
+    *tp_version = have_ga_version ? ga_version : descr_version;
     if (PyUnicode_CompareWithASCIIString(name, "__class__") == 0) {
         if (descriptor == _PyType_Lookup(&PyBaseObject_Type, name)) {
             return DUNDER_CLASS;
@@ -1124,9 +1112,6 @@ do_specialize_instance_load_attr(PyObject* owner, _Py_CODEUNIT* instr, PyObject*
         return -1;
     }
     switch(kind) {
-        case TYPE_CHANGED:
-            SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_TYPE_CHANGED);
-            return -1;
         case OVERRIDING:
             SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_ATTR_OVERRIDING_DESCRIPTOR);
             return -1;
@@ -1370,9 +1355,6 @@ _Py_Specialize_StoreAttr(_PyStackRef owner_st, _Py_CODEUNIT *instr, PyObject *na
         goto fail;
     }
     switch(kind) {
-        case TYPE_CHANGED:
-            SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_ATTR_TYPE_CHANGED);
-            goto fail;
         case OVERRIDING:
             SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_ATTR_OVERRIDING_DESCRIPTOR);
             goto fail;
@@ -1533,10 +1515,6 @@ specialize_class_load_attr(PyObject *owner, _Py_CODEUNIT *instr,
         }
     }
     switch (kind) {
-        case TYPE_CHANGED:
-            SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_ATTR_TYPE_CHANGED);
-            Py_XDECREF(descr);
-            return -1;
         case METHOD:
         case NON_DESCRIPTOR:
             #ifdef Py_GIL_DISABLED