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GeezerVison is showing github.com — gh-149800: Fix macOS universal2 build of perf trampoline by eendebakpt · Pull Request #150365 · python/cpython

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@eendebakpt

@eendebakpt eendebakpt commented May 24, 2026 •
edited by bedevere-app Bot
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Address failing JIT CI, see https://github.com/python/cpython/actions/runs/26343871355/job/77550446716?pr=150324

Claude analysis:

After splitting the perf trampoline into per-architecture .S files in #149894, PY_CORE_CFLAGS still carries -arch arm64 -arch x86_64 on universal2 builds, so each per-arch object becomes a fat Mach-O whose wrong-arch slice is empty (thanks to the #ifdef guards in the sources). lipo -create then refused to merge two fat inputs sharing both architectures:

fatal error: lipo: Python/asm_trampoline_aarch64.o and
Python/asm_trampoline_x86_64.o have the same architectures (x86_64)
and can't be in the same fat output file

Extract the matching slice from each per-arch object with lipo -thin before recombining into asm_trampoline_universal2.o.

The PR #149894 passed because it did not trigger jit builds.

Marking as DO-NOT-MERGE until someone can verify the above is correct.

  • Issue: Refactor perf trampoline proposal: split the assembly per architecture, auto-generate DWARF unwind data #149800

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@eendebakpt
pythongh-149800: Fix macOS universal2 build of perf trampoline
1d010ee 
After splitting the perf trampoline into per-architecture .S files,
PY_CORE_CFLAGS still carries `-arch arm64 -arch x86_64` on universal2
builds, so each per-arch object becomes a fat Mach-O whose wrong-arch
slice is empty (thanks to the `#ifdef` guards in the sources). `lipo
-create` then refused to merge two fat inputs sharing both
architectures:

    fatal error: lipo: Python/asm_trampoline_aarch64.o and
    Python/asm_trampoline_x86_64.o have the same architectures (x86_64)
    and can't be in the same fat output file

Extract the matching slice from each per-arch object with `lipo -thin`
before recombining into `asm_trampoline_universal2.o`.
@eendebakpt
eendebakpt requested review from AA-Turner, emmatyping and erlend-aasland as code owners May 24, 2026 19:34
@eendebakpt eendebakpt added the DO-NOT-MERGE label May 24, 2026
@bedevere-app bedevere-app Bot added the awaiting review label May 24, 2026
@bedevere-app bedevere-app Bot mentioned this pull request May 24, 2026
Refactor perf trampoline proposal: split the assembly per architecture, auto-generate DWARF unwind data #149800
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@eendebakpt
Merge branch 'main' into fix-universal2-trampoline
1ddf61b
@ned-deily

ned-deily commented May 24, 2026

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Looks like @pablogsal was a couple of minutes ahead of you: duplicate of #150364
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@eendebakpt

eendebakpt commented May 24, 2026

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Looks like @pablogsal was a couple of minutes ahead of you: duplicate of #150364

Yeah, he beat me by a minute. I'll close this one, his approach is similar to this one.
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@eendebakpt eendebakpt closed this May 24, 2026
@ned-deily

ned-deily commented May 24, 2026

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Thanks for jumping on it!
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@erlend-aasland erlend-aasland Awaiting requested review from erlend-aasland erlend-aasland is a code owner
@AA-Turner AA-Turner Awaiting requested review from AA-Turner AA-Turner is a code owner
@emmatyping emmatyping Awaiting requested review from emmatyping emmatyping is a code owner

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@eendebakpt @ned-deily
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