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gh-101525: [BOLT] Add GCC's LTO-generated function clones, with computed gotos, to BOLT skip list - #139840

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Oct 19, 2025
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gh-101525: [BOLT] Add GCC's LTO-generated function clones, with computed gotos, to BOLT skip list#139840
corona10 merged 1 commit into
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@stratakis

@stratakisstratakis commented Oct 9, 2025•
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When building with --with-lto, --enable-bolt and --enable-shared, GCC creates optimized function clones with the suffix .lto_priv.0.

The sre_ucs*_match functions use computed gotos, which BOLT cannot optimize, so their .lto_priv.0 clones must be skipped as well.

Static builds and Clang's LTO implementation are not affected.

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@vstinner

vstinner commented Oct 9, 2025

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cc @corona10

@corona10corona10 self-assigned this Oct 9, 2025
@corona10

corona10 commented Oct 14, 2025

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I will try to review this PR until end of this week.

@stratakis
pythongh-101525: Add GCC's LTO-generated function clones, with comput…
d6da34f
…ed gotos, to BOLT skip list
When building with --with-lto, --enable-bolt and --enable-shared, GCC creates
optimized function clones with the suffix .lto_priv.0.
The sre_ucs*_match functions use computed gotos, which BOLT cannot
optimize, so their .lto_priv.0 clones must be skipped as well.
Static builds and Clang's LTO implementation are not affected.
@stratakisstratakis mentioned this pull request Oct 17, 2025
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corona10
corona10 approved these changes Oct 19, 2025
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LGTM!
But since LLVM 20 has been released and llvm/llvm-project#120267
is merged, it’s probably a good time to test without using -skip-funcs :)
cc @zanieb

@corona10
corona10 merged commit bad8d6d into python:mainOct 19, 2025
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@stratakis

stratakis commented Oct 20, 2025

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LGTM! But since LLVM 20 has been released and llvm/llvm-project#120267 is merged, it’s probably a good time to test without using -skip-funcs :) cc @zanieb

I did some testing there with GCC. #140250 works, unless the linker uses -pack-relative-relocs, then those functions fail again.

@stratakis

stratakis commented Nov 6, 2025

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Would it make sense to backport this to previous versions, as it's a bugfix?

@vstinner

vstinner commented Nov 7, 2025

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Would it make sense to backport this to previous versions, as it's a bugfix?

Yes, I think so. Do you agree to backport @corona10?

StanFromIreland pushed a commit to StanFromIreland/cpython that referenced this pull request Dec 6, 2025
@stratakis@StanFromIreland
pythongh-101525: [BOLT] Add GCC's LTO-generated function clones, with…
0685971
… computed gotos, to BOLT skip list (pythongh-139840)
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