gh-87729: add instruction for faster zero-arg super()

carljm · Apr 24, 2023 · Apr 10, 2023 · Apr 13, 2023 · Apr 13, 2023 · Apr 13, 2023
commit 0a0ebe2a71eb46e07c8de7304fa2762768821751
diff --git a/Include/internal/pycore_opcode.h b/Include/internal/pycore_opcode.h
diff --git a/Include/internal/pycore_typeobject.h b/Include/internal/pycore_typeobject.h
@@ -98,6 +98,9 @@ _Py_type_getattro(PyTypeObject *type, PyObject *name);
 PyObject *_Py_slot_tp_getattro(PyObject *self, PyObject *name);
 PyObject *_Py_slot_tp_getattr_hook(PyObject *self, PyObject *name);
 
+PyObject *
+_PySuper_Lookup(PyTypeObject *su_type, PyObject *su_obj, PyObject *name, int *meth_found);
+
 #ifdef __cplusplus
 }
 #endif

diff --git a/Include/opcode.h b/Include/opcode.h
diff --git a/Lib/dis.py b/Lib/dis.py
@@ -41,6 +41,7 @@
 FOR_ITER = opmap['FOR_ITER']
 SEND = opmap['SEND']
 LOAD_ATTR = opmap['LOAD_ATTR']
+LOAD_ZERO_SUPER_ATTR = opmap['LOAD_ZERO_SUPER_ATTR']
 
 CACHE = opmap["CACHE"]
 
@@ -471,7 +472,7 @@ def _get_instructions_bytes(code, varname_from_oparg=None,
                     argval, argrepr = _get_name_info(arg//2, get_name)
                     if (arg & 1) and argrepr:
                         argrepr = "NULL + " + argrepr
-                elif deop == LOAD_ATTR:
+                elif deop == LOAD_ATTR or deop == LOAD_ZERO_SUPER_ATTR:
                     argval, argrepr = _get_name_info(arg//2, get_name)
                     if (arg & 1) and argrepr:
                         argrepr = "NULL|self + " + argrepr

@@ -439,7 +439,8 @@ def _write_atomic(path, data, mode=0o666):
 #     Python 3.12a7 3523 (Convert COMPARE_AND_BRANCH back to COMPARE_OP)
 #     Python 3.12a7 3524 (Shrink the BINARY_SUBSCR caches)
 #     Python 3.12b1 3525 (Shrink the CALL caches)
-#     Python 3.12a7 3526 (Add instrumentation support)
+#     Python 3.12b1 3526 (Add instrumentation support)
+#     Python 3.12b1 3527 (Optimize super() calls)
 
 #     Python 3.13 will start with 3550
 
@@ -456,7 +457,7 @@ def _write_atomic(path, data, mode=0o666):
 # Whenever MAGIC_NUMBER is changed, the ranges in the magic_values array
 # in PC/launcher.c must also be updated.
 
-MAGIC_NUMBER = (3526).to_bytes(2, 'little') + b'\r\n'
+MAGIC_NUMBER = (3527).to_bytes(2, 'little') + b'\r\n'
 
 _RAW_MAGIC_NUMBER = int.from_bytes(MAGIC_NUMBER, 'little')  # For import.c
 

diff --git a/Lib/opcode.py b/Lib/opcode.py
@@ -196,7 +196,7 @@ def pseudo_op(name, op, real_ops):
 def_op('DELETE_DEREF', 139)
 hasfree.append(139)
 jrel_op('JUMP_BACKWARD', 140)    # Number of words to skip (backwards)
-
+name_op('LOAD_ZERO_SUPER_ATTR', 141)
 def_op('CALL_FUNCTION_EX', 142)  # Flags
 
 def_op('EXTENDED_ARG', 144)
@@ -264,6 +264,7 @@ def pseudo_op(name, op, real_ops):
 pseudo_op('JUMP_NO_INTERRUPT', 261, ['JUMP_FORWARD', 'JUMP_BACKWARD_NO_INTERRUPT'])
 
 pseudo_op('LOAD_METHOD', 262, ['LOAD_ATTR'])
+pseudo_op('LOAD_ZERO_SUPER_METHOD', 263, ['LOAD_ZERO_SUPER_ATTR'])
 
 MAX_PSEUDO_OPCODE = MIN_PSEUDO_OPCODE + len(_pseudo_ops) - 1
 

diff --git a/Lib/test/shadowed_super.py b/Lib/test/shadowed_super.py
@@ -0,0 +1,7 @@
+class super:
+    msg = "truly super"
+
+
+class C:
+    def method(self):
+        return super().msg
diff --git a/Lib/test/test_super.py b/Lib/test/test_super.py
@@ -1,6 +1,8 @@
 """Unit tests for zero-argument super() & related machinery."""
 
 import unittest
+from unittest.mock import patch
+from test import shadowed_super
 
 
 class A:
@@ -283,17 +285,28 @@ def f(self):
     def test_obscure_super_errors(self):
         def f():
             super()
-        self.assertRaises(RuntimeError, f)
+        with self.assertRaisesRegex(RuntimeError, r"no arguments"):
+            f()
+
+        class C:
+            def f():
+                super()
+        with self.assertRaisesRegex(RuntimeError, r"no arguments"):
+            C.f()
+
         def f(x):
             del x
             super()
-        self.assertRaises(RuntimeError, f, None)
+        with self.assertRaisesRegex(RuntimeError, r"arg\[0\] deleted"):
+            f(None)
+
         class X:
             def f(x):
                 nonlocal __class__
                 del __class__
                 super()
-        self.assertRaises(RuntimeError, X().f)
+        with self.assertRaisesRegex(RuntimeError, r"empty __class__ cell"):
+            X().f()
 
     def test_cell_as_self(self):
         class X:
@@ -325,6 +338,38 @@ def test_super_argtype(self):
         with self.assertRaisesRegex(TypeError, "argument 1 must be a type"):
             super(1, int)
 
+    def test_shadowed_global(self):
+        self.assertEqual(shadowed_super.C().method(), "truly super")
+
+    def test_shadowed_local(self):
+        class super:
+            msg = "quite super"
+
+        class C:
+            def method(self):
+                return super().msg
+
+        self.assertEqual(C().method(), "quite super")
+
+    def test_shadowed_dynamic(self):
+        class MySuper:
+            msg = "super super"
+
+        class C:
+            def method(self):
+                return super().msg
+
+        with patch("test.test_super.super", MySuper) as m:
+            self.assertEqual(C().method(), "super super")
+
+    def test_attribute_error(self):
+        class C:
+            def method(self):
+                return super().msg
+
+        with self.assertRaisesRegex(AttributeError, "'super' object has no attribute 'msg'"):
+            C().method()
+
 
 if __name__ == "__main__":
     unittest.main()
@@ -9358,14 +9358,15 @@ super_repr(PyObject *self)
 }
 
 static PyObject *
-super_getattro(PyObject *self, PyObject *name)
+do_super_lookup(superobject *su, PyTypeObject *su_type, PyObject *su_obj,
+                PyTypeObject *su_obj_type, PyObject *name, int *meth_found)
 {
-    superobject *su = (superobject *)self;
     PyTypeObject *starttype;
-    PyObject *mro;
+    PyObject *mro, *res;
     Py_ssize_t i, n;
+    int temp_su = 0;
 
-    starttype = su->obj_type;
+    starttype = su_obj_type;
     if (starttype == NULL)
         goto skip;
 
@@ -9385,7 +9386,7 @@ super_getattro(PyObject *self, PyObject *name)
 
     /* No need to check the last one: it's gonna be skipped anyway.  */
     for (i = 0; i+1 < n; i++) {
-        if ((PyObject *)(su->type) == PyTuple_GET_ITEM(mro, i))
+        if ((PyObject *)(su_type) == PyTuple_GET_ITEM(mro, i))
             break;
     }
     i++;  /* skip su->type (if any)  */
@@ -9400,19 +9401,22 @@ super_getattro(PyObject *self, PyObject *name)
         PyObject *dict = _PyType_CAST(obj)->tp_dict;
         assert(dict != NULL && PyDict_Check(dict));
 
-        PyObject *res = PyDict_GetItemWithError(dict, name);
+        res = PyDict_GetItemWithError(dict, name);
         if (res != NULL) {
             Py_INCREF(res);
-
-            descrgetfunc f = Py_TYPE(res)->tp_descr_get;
-            if (f != NULL) {
-                PyObject *res2;
-                res2 = f(res,
-                    /* Only pass 'obj' param if this is instance-mode super
-                       (See SF ID #743627)  */
-                    (su->obj == (PyObject *)starttype) ? NULL : su->obj,
-                    (PyObject *)starttype);
-                Py_SETREF(res, res2);
+            if (meth_found && _PyType_HasFeature(Py_TYPE(res), Py_TPFLAGS_METHOD_DESCRIPTOR)) {
+                *meth_found = 1;
+            } else {
+                descrgetfunc f = Py_TYPE(res)->tp_descr_get;
+                if (f != NULL) {
+                    PyObject *res2;
+                    res2 = f(res,
+                        /* Only pass 'obj' param if this is instance-mode super
+                        (See SF ID #743627)  */
+                        (su_obj == (PyObject *)starttype) ? NULL : su_obj,
+                        (PyObject *)starttype);
+                    Py_SETREF(res, res2);
+                }
             }
 
             Py_DECREF(mro);
@@ -9428,7 +9432,25 @@ super_getattro(PyObject *self, PyObject *name)
     Py_DECREF(mro);
 
   skip:
-    return PyObject_GenericGetAttr(self, name);
+    if (su == NULL) {
+        su = PyObject_Vectorcall((PyObject *)&PySuper_Type, NULL, 0, NULL);
+        if (su == NULL) {
+            return NULL;
+        }
+        temp_su = 1;
+    }
+    res = PyObject_GenericGetAttr((PyObject *)su, name);
+    if (temp_su) {
+        Py_DECREF(su);
+    }
+    return res;
+}
+
+static PyObject *
+super_getattro(PyObject *self, PyObject *name)
+{
+    superobject *su = (superobject *)self;
+    return do_super_lookup(su, su->type, su->obj, su->obj_type, name, NULL);
 }
 
 static PyTypeObject *
@@ -9484,6 +9506,18 @@ supercheck(PyTypeObject *type, PyObject *obj)
     return NULL;
 }
 
+PyObject *
+_PySuper_Lookup(PyTypeObject *su_type, PyObject *su_obj, PyObject *name, int *meth_found)
+{
+    PyTypeObject *su_obj_type = supercheck(su_type, su_obj);
+    if (su_obj_type == NULL) {
+        return NULL;
+    }
+    PyObject *res = do_super_lookup(NULL, su_type, su_obj, su_obj_type, name, meth_found);
+    Py_DECREF(su_obj_type);
+    return res;
+}
+
 static PyObject *
 super_descr_get(PyObject *self, PyObject *obj, PyObject *type)
 {