bpo-45697: PyType_IsSubtype: Return early for identical type objects #29380
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bpo-45697: PyType_IsSubtype: Return early for identical type objects
Based on real world profiling data we collected, a vast amount of
PyType_IsSubtypecalls are coming fromtype_call, when it decides whether__init__should run or not.In the common case, the arguments to this call are identical, but the implementation still walks the MRO.
By returning early for identical types, the common case can be optimized with a non-trivial performance gain.
https://bugs.python.org/issue45697