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bpo-42161: mathmodule.c: move _PyLong_GetOne() loop invariant#26391

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vstinner merged 1 commit into
python:mainfrom
vstinner:math_micro_optim
May 26, 2021
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bpo-42161: mathmodule.c: move _PyLong_GetOne() loop invariant#26391
vstinner merged 1 commit into
python:mainfrom
vstinner:math_micro_optim

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@vstinner vstinner commented May 26, 2021 •
edited by bedevere-bot
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Move _PyLong_GetZero() and _PyLong_GetOne() loop invariants outside
loops in functions:

  • math.comb()
  • math.gcd()
  • math.lcm()
  • math.perm()

https://bugs.python.org/issue42161

@vstinner
bpo-42161: mathmodule.c: move _PyLong_GetOne() loop invariant …
4b6dea6 
Move _PyLong_GetZero() and _PyLong_GetOne() loop invariants outside
loops in functions:

* math.comb()
* math.gcd()
* math.lcm()
* math.perm()
@vstinner vstinner added the needs backport to 3.10 only security fixes label May 26, 2021
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vstinner commented May 26, 2021

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This change should be backport to 3.10 since it fix a minor performance regression introduced in Python 3.10: https://bugs.python.org/issue42161#msg388988

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vstinner commented May 26, 2021

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cc @rhettinger

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vstinner commented May 26, 2021

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I didn't notice that _PyLong_GetZero() and _PyLong_GetOne() were used in loops in Modules/mathmodule.c when I wrote my commit 3783413 (I tried to pay attention to that, to avoid performance regression).

@vstinner vstinner merged commit 3e7ee02 into python:main May 26, 2021
@miss-islington

miss-islington commented May 26, 2021

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Thanks @vstinner for the PR 🌮🎉.. I'm working now to backport this PR to: 3.10.
🐍🍒⛏🤖

@vstinner vstinner deleted the math_micro_optim branch May 26, 2021 22:51
miss-islington pushed a commit to miss-islington/cpython that referenced this pull request May 26, 2021
@vstinner @miss-islington
bpo-42161: mathmodule.c: move _PyLong_GetOne() loop invariant (python… …
7edc52a 
…GH-26391)

Move _PyLong_GetZero() and _PyLong_GetOne() loop invariants outside
loops in functions:

* math.comb()
* math.gcd()
* math.lcm()
* math.perm()
(cherry picked from commit 3e7ee02)

Co-authored-by: Victor Stinner <vstinner@python.org>
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bedevere-bot commented May 26, 2021

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GH-26393 is a backport of this pull request to the 3.10 branch.

@bedevere-bot bedevere-bot removed the needs backport to 3.10 only security fixes label May 26, 2021
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vstinner commented May 26, 2021

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Thanks for the review @erlend-aasland.

vstinner added a commit that referenced this pull request May 26, 2021
@miss-islington @vstinner
bpo-42161: mathmodule.c: move _PyLong_GetOne() loop invariant (GH-26391… …
4115996 
…) (GH-26393)

Move _PyLong_GetZero() and _PyLong_GetOne() loop invariants outside
loops in functions:

* math.comb()
* math.gcd()
* math.lcm()
* math.perm()
(cherry picked from commit 3e7ee02)

Co-authored-by: Victor Stinner <vstinner@python.org>
@pablogsal pablogsal mentioned this pull request Jul 18, 2021
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@erlend-aasland erlend-aasland erlend-aasland approved these changes

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