GH-131033: Enable the optimizing macros UNLIKELY and LIKELY for clang-cl on Windows by chris-eibl · Pull Request #131019 · python/cpython · GitHub

Maybe a skip news?

Performance neutral, see #131033.

Issue: Let clang on Linux and clang-cl on Windows "see" more optimizing macros #131033

clang-cl on Windows

Ups, expat_external.h so this one should be left alone (or thouched upstream). So setting to draft for now,

Not a skip issue IMO because benchmarks reported on the issue + possible discussion on the issue rather than the PR may be worthwile.

Also it's sometimes good to be able to gather similar improvements under an umbrella issue

This reverts commit 01183d7.

@chris-eibl could you add a small NEWS entry under the build section? I think it would be good to know that these macros are now enabled when possible (at least for object allocation). Or maybe the formulation would be too obscure? if this is the case, just add skip news and I'll merge.

I'd go with skip news, since according to @zooba #131279 (comment)

[...], since we still aren't technically supporting clang-cl on Windows yet,

clang-cl on Windows is quite niche, and I can't think of anything better than something like

Enable the optimizing macros UNLIKELY and LIKELY for clang-cl on Windows in obmalloc.c.

which is indeed not much help.

I'd happily blurb it like so if this deems reasonable.

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot s390x Fedora Stable Refleaks 3.x (tier-3) has failed when building commit 95d6e0b.

What do you need to do:

Don't panic.
Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1641/builds/810) and take a look at the build logs.
Check if the failure is related to this commit (95d6e0b) or if it is a false positive.
If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1641/builds/810

Failed tests:

test_external_inspection

Failed subtests:

test_only_active_thread - test.test_external_inspection.TestGetStackTrace.test_only_active_thread

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-s390x.refleak/build/Lib/test/test_external_inspection.py", line 1246, in test_only_active_thread
    self.assertEqual(
    ~~~~~~~~~~~~~~~~^
        len(gil_traces), 1, "Should have exactly one GIL holder"
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
AssertionError: 0 != 1 : Should have exactly one GIL holder

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 FreeBSD Refleaks 3.x (tier-3) has failed when building commit 95d6e0b.

What do you need to do:

Don't panic.
Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1613/builds/1889) and take a look at the build logs.
Check if the failure is related to this commit (95d6e0b) or if it is a false positive.
If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1613/builds/1889

Test leaking resources:

test_events: references
test_events: memory blocks

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/support/__init__.py", line 837, in gc_collect
    gc.collect()
    ~~~~~~~~~~^^
ResourceWarning: unclosed <socket.socket fd=9, family=2, type=1, proto=6, laddr=('127.0.0.1', 22458), raddr=('127.0.0.1', 22459)>
Task was destroyed but it is pending!
task: <Task pending name='Task-2677' coro=<BaseSelectorEventLoop._accept_connection2() done, defined at /buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/asyncio/selector_events.py:217> wait_for=<Future pending cb=[Task.task_wakeup()]>>
Warning -- Unraisable exception
Exception ignored while calling deallocator <function _SelectorTransport.__del__ at 0x843f20350>:
Traceback (most recent call last):
  File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/asyncio/selector_events.py", line 873, in __del__
    _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
    ~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ResourceWarning: unclosed transport <_SelectorSocketTransport closing fd=9>
k


Traceback (most recent call last):
  File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/test/support/__init__.py", line 837, in gc_collect
    gc.collect()
    ~~~~~~~~~~^^
ResourceWarning: unclosed <socket.socket fd=9, family=2, type=1, proto=6, laddr=('127.0.0.1', 28487), raddr=('127.0.0.1', 28488)>
Task was destroyed but it is pending!
task: <Task pending name='Task-2435' coro=<BaseSelectorEventLoop._accept_connection2() done, defined at /buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/asyncio/selector_events.py:217> wait_for=<Future pending cb=[Task.task_wakeup()]>>
Warning -- Unraisable exception
Exception ignored while calling deallocator <function _SelectorTransport.__del__ at 0x8453bc350>:
Traceback (most recent call last):
  File "/buildbot/buildarea/3.x.ware-freebsd.refleak/build/Lib/asyncio/selector_events.py", line 873, in __del__
    _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
    ~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ResourceWarning: unclosed transport <_SelectorSocketTransport closing fd=9>
k

chris-eibl added 2 commits March 9, 2025 11:50

Enable XML_ATTR_MALLOC and XML_ATTR_ALLOC_SIZE for

01183d7

clang-cl on Windows

Enable UNLIKELY and LIKELY for clang-cl on Windows

16a7f46

bedevere-app Bot added the awaiting review label Mar 9, 2025

chris-eibl marked this pull request as draft March 9, 2025 18:25

bedevere-app Bot removed the awaiting review label Mar 9, 2025

Fidget-Spinner approved these changes Mar 9, 2025

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bedevere-app Bot added the awaiting merge label Mar 9, 2025

Revert "Enable XML_ATTR_MALLOC and XML_ATTR_ALLOC_SIZE "

1c4a55d

This reverts commit 01183d7.

chris-eibl mentioned this pull request Mar 10, 2025

Let clang on Linux and clang-cl on Windows "see" more optimizing macros #131033

Closed

chris-eibl changed the title Enable the optimizing macros UNLIKELY, LIKELY, XML_ATTR_MALLOC and XML_ATTR_ALLOC_SIZE for clang-cl on Windows GH-131033: Enable the optimizing macros UNLIKELY and LIKELY for clang-cl on Windows Mar 10, 2025

chris-eibl marked this pull request as ready for review March 10, 2025 09:02

bedevere-app Bot added awaiting review and removed awaiting merge labels Mar 10, 2025

chris-eibl added the skip news label Aug 23, 2025

picnixz approved these changes Aug 23, 2025

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bedevere-app Bot added awaiting merge and removed awaiting review labels Aug 23, 2025

zooba reviewed Aug 25, 2025

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Comment thread Objects/obmalloc.c

update comment

577bba7

zooba merged commit 95d6e0b into python:main Aug 25, 2025
46 checks passed

bedevere-app Bot removed the awaiting merge label Aug 25, 2025

chris-eibl deleted the clang_opt branch August 25, 2025 21:28

GH-131033: Enable the optimizing macros UNLIKELY and LIKELY for clang-cl on Windows by chris-eibl · Pull Request #131019 · python/cpython · GitHub

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GH-131033: Enable the optimizing macros UNLIKELY and LIKELY for clang-cl on Windows - #131019

GH-131033: Enable the optimizing macros UNLIKELY and LIKELY for clang-cl on Windows#131019
zooba merged 4 commits into
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chris-eibl:clang_opt

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GH-131033: Enable the optimizing macros UNLIKELY and LIKELY for clang-cl on Windows by chris-eibl · Pull Request #131019 · python/cpython · GitHub

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GH-131033: Enable the optimizing macros UNLIKELY and LIKELY for clang-cl on Windows - #131019

GH-131033: Enable the optimizing macros UNLIKELY and LIKELY for clang-cl on Windows#131019zooba merged 4 commits intopython:mainpython/cpython:mainfrom chris-eibl:clang_optchris-eibl/cpython:clang_optCopy head branch name to clipboard

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GH-131033: Enable the optimizing macros UNLIKELY and LIKELY for clang-cl on Windows#131019
zooba merged 4 commits into
python:mainfrom
chris-eibl:clang_opt

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