New submission from Vladimir Matveev <desco...@gmail.com>:
Calling methods and lookup up attributes when receiver is `super()` has extra
cost comparing to regular attribute lookup. It mainly comes from the need to
allocate and initialize the instance of the `super` which for zero argument
case also include peeking into frame/code object for the `__class__` cell and
first argument. In addition because `PySuper_Type` has custom implementation of
tp_getattro - `_PyObject_GetMethod` would always return bound method.
```
import timeit
setup = """
class A:
def f(self): pass
class B(A):
def f(self): super().f()
def g(self): A.f(self)
b = B()
"""
print(timeit.timeit("b.f()", setup=setup, number=20000000))
print(timeit.timeit("b.g()", setup=setup, number=20000000))
7.329449548968114
3.892987059080042
```
One option to improve it could be to make compiler/interpreter aware of super
calls so they can be treated specially. Attached patch introduces two new
opcodes LOAD_METHOD_SUPER and LOAD_ATTR_SUPER that are intended to be
counterparts for LOAD_METHOD and LOAD_ATTR for cases when receiver is super
with either zero or two arguments.
Immediate argument for both LOAD_METHOD_SUPER and LOAD_ATTR_SUPER is a pair
that consist of:
0: index of method/attribute in co_names
1: Py_True if super was originally called with 0 arguments and Py_False
otherwise.
Both LOAD_METHOD_SUPER and LOAD_ATTR_SUPER expect 3 elements on the stack:
TOS3: global_super
TOS2: type
TOS1: self/cls
Result of LOAD_METHOD_SUPER is the same as LOAD_METHOD.
Result of LOAD_ATTR_SUPER is the same as LOAD_ATTR
In runtime both LOAD_METHOD_SUPER and LOAD_ATTR_SUPER will check if
`global_super` is `PySuper_Type` to handle situations when `super` is patched.
If `global_super` is `PySuper_Type` then it can use dedicated routine to
perform the lookup for provided `__class__` and `cls/self` without allocating
new `super` instance. If `global_super` is different from `PySuper_Type` then
runtime will fallback to the original logic using `global_super` and original
number of arguments that was captured in immediate.
Benchmark results with patch:
4.381768501014449
3.9492998640052974
----------
components: Interpreter Core
messages: 389114
nosy: v2m
priority: normal
severity: normal
status: open
title: Use dedicated opcodes to speed up calls/attribute lookups with super()
as receiver
versions: Python 3.10
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue43563>
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