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gh-87729: add LOAD_SUPER_ATTR instruction for faster super() (#103497)
This speeds up `super()` (by around 85%, for a simple one-level `super().meth()` microbenchmark) by avoiding allocation of a new single-use `super()` object on each use.
1 parent 22bed58 commit 0dc8b50

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-408
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‎Doc/library/dis.rst

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@@ -1036,6 +1036,24 @@ iterations of the loop.
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pushed to the stack before the attribute or unbound method respectively.
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.. opcode:: LOAD_SUPER_ATTR (namei)
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This opcode implements :func:`super` (e.g. ``super().method()`` and
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``super().attr``). It works the same as :opcode:`LOAD_ATTR`, except that
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``namei`` is shifted left by 2 bits instead of 1, and instead of expecting a
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single receiver on the stack, it expects three objects (from top of stack
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down): ``self`` (the first argument to the current method), ``cls`` (the
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class within which the current method was defined), and the global ``super``.
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The low bit of ``namei`` signals to attempt a method load, as with
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:opcode:`LOAD_ATTR`.
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The second-low bit of ``namei``, if set, means that this was a two-argument
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call to :func:`super` (unset means zero-argument).
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.. versionadded:: 3.12
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.. opcode:: COMPARE_OP (opname)
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Performs a Boolean operation. The operation name can be found in

‎Include/internal/pycore_opcode.h

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‎Include/internal/pycore_typeobject.h

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@@ -98,6 +98,9 @@ _Py_type_getattro(PyTypeObject *type, PyObject *name);
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PyObject *_Py_slot_tp_getattro(PyObject *self, PyObject *name);
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PyObject *_Py_slot_tp_getattr_hook(PyObject *self, PyObject *name);
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PyObject *
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_PySuper_Lookup(PyTypeObject *su_type, PyObject *su_obj, PyObject *name, int *meth_found);
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#ifdef __cplusplus
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}
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#endif

‎Include/opcode.h

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‎Lib/dis.py

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@@ -41,6 +41,7 @@
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FOR_ITER = opmap['FOR_ITER']
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SEND = opmap['SEND']
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LOAD_ATTR = opmap['LOAD_ATTR']
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LOAD_SUPER_ATTR = opmap['LOAD_SUPER_ATTR']
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CACHE = opmap["CACHE"]
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@@ -475,6 +476,10 @@ def _get_instructions_bytes(code, varname_from_oparg=None,
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argval, argrepr = _get_name_info(arg//2, get_name)
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if (arg & 1) and argrepr:
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argrepr = "NULL|self + " + argrepr
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elif deop == LOAD_SUPER_ATTR:
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argval, argrepr = _get_name_info(arg//4, get_name)
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if (arg & 1) and argrepr:
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argrepr = "NULL|self + " + argrepr
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else:
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argval, argrepr = _get_name_info(arg, get_name)
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elif deop in hasjabs:

‎Lib/importlib/_bootstrap_external.py

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

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@@ -196,7 +196,7 @@ def pseudo_op(name, op, real_ops):
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def_op('DELETE_DEREF', 139)
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hasfree.append(139)
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jrel_op('JUMP_BACKWARD', 140) # Number of words to skip (backwards)
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name_op('LOAD_SUPER_ATTR', 141)
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def_op('CALL_FUNCTION_EX', 142) # Flags
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def_op('EXTENDED_ARG', 144)
@@ -264,6 +264,9 @@ def pseudo_op(name, op, real_ops):
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pseudo_op('JUMP_NO_INTERRUPT', 261, ['JUMP_FORWARD', 'JUMP_BACKWARD_NO_INTERRUPT'])
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pseudo_op('LOAD_METHOD', 262, ['LOAD_ATTR'])
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pseudo_op('LOAD_SUPER_METHOD', 263, ['LOAD_SUPER_ATTR'])
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pseudo_op('LOAD_ZERO_SUPER_METHOD', 264, ['LOAD_SUPER_ATTR'])
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pseudo_op('LOAD_ZERO_SUPER_ATTR', 265, ['LOAD_SUPER_ATTR'])
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MAX_PSEUDO_OPCODE = MIN_PSEUDO_OPCODE + len(_pseudo_ops) - 1
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‎Lib/test/shadowed_super.py

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@@ -0,0 +1,7 @@
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class super:
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msg = "truly super"
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class C:
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def method(self):
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return super().msg

‎Lib/test/test_gdb.py

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@@ -962,7 +962,7 @@ def test_wrapper_call(self):
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cmd = textwrap.dedent('''
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class MyList(list):
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def __init__(self):
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super().__init__() # wrapper_call()
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super(*[]).__init__() # wrapper_call()
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id("first break point")
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l = MyList()

‎Lib/test/test_super.py

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"""Unit tests for zero-argument super() & related machinery."""
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import unittest
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from unittest.mock import patch
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from test import shadowed_super
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class A:
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def test_obscure_super_errors(self):
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def f():
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super()
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self.assertRaises(RuntimeError, f)
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with self.assertRaisesRegex(RuntimeError, r"no arguments"):
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f()
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class C:
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def f():
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super()
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with self.assertRaisesRegex(RuntimeError, r"no arguments"):
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C.f()
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def f(x):
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del x
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super()
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self.assertRaises(RuntimeError, f, None)
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with self.assertRaisesRegex(RuntimeError, r"arg\[0\] deleted"):
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f(None)
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class X:
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def f(x):
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nonlocal __class__
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del __class__
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super()
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self.assertRaises(RuntimeError, X().f)
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with self.assertRaisesRegex(RuntimeError, r"empty __class__ cell"):
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X().f()
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def test_cell_as_self(self):
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class X:
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with self.assertRaisesRegex(TypeError, "argument 1 must be a type"):
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super(1, int)
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def test_shadowed_global(self):
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self.assertEqual(shadowed_super.C().method(), "truly super")
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def test_shadowed_local(self):
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class super:
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msg = "quite super"
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class C:
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def method(self):
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return super().msg
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self.assertEqual(C().method(), "quite super")
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def test_shadowed_dynamic(self):
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class MySuper:
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msg = "super super"
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class C:
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def method(self):
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return super().msg
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with patch("test.test_super.super", MySuper) as m:
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self.assertEqual(C().method(), "super super")
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def test_shadowed_dynamic_two_arg(self):
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call_args = []
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class MySuper:
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def __init__(self, *args):
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call_args.append(args)
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msg = "super super"
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class C:
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def method(self):
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return super(1, 2).msg
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with patch("test.test_super.super", MySuper) as m:
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self.assertEqual(C().method(), "super super")
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self.assertEqual(call_args, [(1, 2)])
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def test_attribute_error(self):
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class C:
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def method(self):
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return super().msg
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with self.assertRaisesRegex(AttributeError, "'super' object has no attribute 'msg'"):
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C().method()
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def test_bad_first_arg(self):
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class C:
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def method(self):
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return super(1, self).method()
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with self.assertRaisesRegex(TypeError, "argument 1 must be a type"):
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C().method()
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def test_super___class__(self):
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class C:
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def method(self):
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return super().__class__
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self.assertEqual(C().method(), super)
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def test_super_subclass___class__(self):
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class mysuper(super):
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pass
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class C:
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def method(self):
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return mysuper(C, self).__class__
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self.assertEqual(C().method(), mysuper)
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if __name__ == "__main__":
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unittest.main()

‎Misc/NEWS.d/next/Core and Builtins/2023-04-12-20-22-03.gh-issue-87729.99A7UO.rst

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Add :opcode:`LOAD_SUPER_ATTR` to speed up ``super().meth()`` and ``super().attr`` calls.

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