[issue42825] Build libraries with "/OPT:REF" linker optimization on Windows
Austin Lamb added the comment: Thanks Steve! -- ___ Python tracker <https://bugs.python.org/issue42825> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue42825] Build libraries with "/OPT:REF" linker optimization on Windows
Austin Lamb added the comment: What are the next steps for this - anything else I can provide, or is someone able to take a look at the Pull Request? Thanks! -- ___ Python tracker <https://bugs.python.org/issue42825> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue42825] Build libraries with "/OPT:REF" linker optimization on Windows
Austin Lamb added the comment: You're right to think that folding is a problem Steve, but thankfully my PR does not enable COMDAT folding for that very reason :). /OPT:ICF enables identical COMDAT folding, but surprisingly-to-me /OPT:REF seems to still enable a small amount of folding (I confirmed with the linker dev at Microsoft that this is true). Thus, just /OPT:REF alone caused test failures as there are test cases verifying COMDAT folding didn't occur. Thus, in my PR I am using /OPT:REF,NOICF to explicitly disable any ICF'ing at all and I see no folding occurring anywhere, and those COMDAT-folding-sensitive tests pass with that flag. The dumpbin /exports output is identical after this change. -- ___ Python tracker <https://bugs.python.org/issue42825> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue42825] Build libraries with "/OPT:REF" linker optimization on Windows
Austin Lamb added the comment: Ping - can anyone suggest either how ctypes does its exporting, or suggest tests I could run to confirm if this change affects python code? The entire test suite in the repo passes. -- ___ Python tracker <https://bugs.python.org/issue42825> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue42825] Build libraries with "/OPT:REF" linker optimization on Windows
Austin Lamb added the comment: I don't know much about how ctypes exposes stuff - are these exposed as DLL exports? Or if not, how do they get exposed? The linker will remove things it can't find a callsite for, but it leaves in exported functions as of course those are by definition externally callable. If ctypes is called another way, I can help confirm whether anything is accidentally being stripped out. -- ___ Python tracker <https://bugs.python.org/issue42825> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue42825] Optimization opportunity on Windows
Change by Austin Lamb : -- keywords: +patch pull_requests: +22928 stage: -> patch review pull_request: https://github.com/python/cpython/pull/24098 ___ Python tracker <https://bugs.python.org/issue42825> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue42825] Optimization opportunity on Windows
New submission from Austin Lamb : I noticed that CPython and the various libraries built out of the repo aren't using the "/OPT:REF" linker optimization on Windows. This optimization allows the linker to throw away dead/unreachable code, resulting in a substantial decrease in binary size. That in turn also reduces the amount of Disk I/O that must be done to get these binaries in memory (which can be meaningful on spinning hard drives that are still rather common), and the reference set of applications using Python. I'll send a PR for this shortly, just filing the issue to be able to reference it in the PR. -- components: Windows messages: 384333 nosy: Austin-Lamb, paul.moore, steve.dower, tim.golden, zach.ware priority: normal severity: normal status: open title: Optimization opportunity on Windows type: performance versions: Python 3.10 ___ Python tracker <https://bugs.python.org/issue42825> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
