bpo-44525: Split calls into PRECALL and CALL #30011
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…CALL_FUNCTION_KW.
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This is really exciting work, deltablue, hexiom and mako are pretty CALL_X heavy programs. So the pyperformance results looks promising! I'll try to review within the next week unless someone else beats me to it. |
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| static PyMethodDescrObject *_list_append = NULL; |
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Something tells me Victor (and the subinterpreter folks) won't be happy seeing this 😄 . We can probably move it to interpreter state in another PR. WDYT?
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PyList_Type is a static global and part of the ABI: https://github.com/python/cpython/blob/main/Misc/stable_abi.txt#L864
So the list.append method descriptor might as well be a static global as well (at least for now).
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| _list_append = (PyMethodDescrObject *)_PyType_LookupId(&PyList_Type, &PyId_append); |
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Side note: If we're going this route to make specialization attempts cheaper, we could consider a unified way to cache these types of lookups. E.g. len and isinstance specializations need looking into builtins() dict every time. Caching the len and isinstance objects plus the builtins() dict tag would make them much cheaper.
…tment around calls a bit more maintainable.
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| Replace the four call bytecode instructions which one pre-call instruction | ||
| and two call instructions. | ||
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| Removes ``CALL_FUNCTION``, ``CALL_FUNCTION_KW``, ``CALL_METHOD`` and | ||
| ``CALL_METHOD_KW``. | ||
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| Adds ``CALL_NO_KW`` and ``CALL_KW`` call instructions, and | ||
| ``PRECALL_METHOD`` prefix for pairing with ``LOAD_METHOD``. |
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We've started keeping another log of bytecode changes over in What's New. That section should probably be updated with these changes (especially since CALL_METHOD and CALL_METHOD_KW are mentioned there already).
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Specializing calls is going to need a lot of specialized bytecode if we want to specialize all four of
CALL_FUNCTION,CALL_FUNCTION_KW,CALL_METHODandCALL_METHOD_KWindependently.Since the only real difference between between the
CALL_FUNCTIONandCALL_METHODforms is shifting the start of the arguments by one or two, it makes sense to move that into a pre-call instruction.The above four opcodes are replaced by:
PRECALL_METHOD: Pairs withLOAD_METHOD. Set the pre-call argument delta, and post-call stack shrink for a method call.CALL_NO_KW: CombinesCALL_FUNCTIONandCALL_METHODCALL_KW: CombinesCALL_FUNCTION_KWandCALL_METHOD_KWThis means that we can specialize calls to methods with much extra effort.
Specialization of calls to Python methods happens almost for free (we need an additional check that the number of args is as expected).
Specialization of method descriptors needs a few more instructions, but no extra
ADAPTIVEform is needed.1% speedup
I think that the slowdowns are calls to bound-methods. So they are next on the list.
https://bugs.python.org/issue44525