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bpo-45295: Speed up C classmethod calls via unbound classmethods#28572

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Fidget-Spinner wants to merge 6 commits into
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Fidget-Spinner:classmethod_unbound_only
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bpo-45295: Speed up C classmethod calls via unbound classmethods#28572
Fidget-Spinner wants to merge 6 commits into
python:mainfrom
Fidget-Spinner:classmethod_unbound_only

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@Fidget-Spinner

@Fidget-Spinner Fidget-Spinner commented Sep 26, 2021 •
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  1. _PyObject_GetMethod now supports C classmethods.
  2. PyClassMethodDescr_Type now supports vectorcall.

This PR has two changes because supporting vectorcall made it easier to call unbound cclassmethods. Without vectorcall, I'd need to write a lot of custom code.

Moving to vectorcall also means we can get rid of the old calling code :).

Microbench on Windows Release, pyperformance coming later (once tests pass):

python.exe -m timeit "int.from_bytes(b'')"
Main:
2000000 loops, best of 5: 107 nsec per loop
Patched:
5000000 loops, best of 5: 72.4 nsec per loop

This is without specialization support. That will come in another PR.

https://bugs.python.org/issue45295

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Fidget-Spinner marked this pull request as draft September 26, 2021 16:42
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Fidget-Spinner commented Sep 26, 2021

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I've cancelled the workflows temporarily to save resources. test_descr and test_datetime currently fail.

@Fidget-Spinner Fidget-Spinner changed the title bpo-issue45295: Speed up C classmethod calls via unbound classmethods bpo-45295: Speed up C classmethod calls via unbound classmethods Sep 27, 2021
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Fidget-Spinner marked this pull request as ready for review September 27, 2021 10:10
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Fidget-Spinner commented Sep 27, 2021

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Pinging @markshannon as I think this may interest you. Not sure who else to ping for descriptor stuff, maybe the original LOAD_METHOD + CALL_METHOD folks?

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Fidget-Spinner commented Sep 29, 2021

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Knowing my luck with benchmarks, pyperformance showed no change :(.

The current code allows for improving Python classmethods too. After implementing that I will try running this against the Pyston benchmark suite instead (pyperformance almost doesnt use any classmethods).

If that too doesnt show any speedups i will just abandon this PR.

@corona10 corona10 mentioned this pull request Oct 4, 2021
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@markshannon

markshannon commented Oct 18, 2021

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What are you trying to speed up here? Could you provide an example?

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Fidget-Spinner commented Oct 18, 2021 •
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What are you trying to speed up here? Could you provide an example?

All builtin classmethod calls. So int.from_bytes(), dict.fromkeys() etc. In theory this can also be extended to Python classmethod calls.

@Fidget-Spinner Fidget-Spinner mentioned this pull request Sep 10, 2022
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@Siyet Siyet mentioned this pull request Apr 11, 2026
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@Fidget-Spinner @markshannon @the-knights-who-say-ni @ezio-melotti @bedevere-bot