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Fix atomic_ref<16 bytes>::is_always_lock_free #4478

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StephanTLavavej merged 14 commits into from
Mar 19, 2024
Merged

Fix atomic_ref<16 bytes>::is_always_lock_free #4478

StephanTLavavej merged 14 commits into from
Mar 19, 2024

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@AlexGuteniev AlexGuteniev commented Mar 14, 2024

Fixes #4472

  • Invent always-lock-free compile-time check independently from atomic<T>
    • Sharing the checks implementation is a bomb for vNext. In vNext I expect atomic<3 bytes> to be always-lock-free, but not atomic_ref<3 bytes>
    • Having the template constant in global scope is unnecessary, atomic_ref<T> doesn't have volatile things
  • Expand test matrix for that
    • Requires DCAS machine, but it is Win8+ requirement
    • clang-cl wants cx16 feature enabled for that

@AlexGuteniev AlexGuteniev requested a review from a team as a code owner March 14, 2024 10:53
@AlexGuteniev AlexGuteniev changed the title Sulfur Fix atomic_ref<16 bytes>::is_always_lock_free Mar 14, 2024
@StephanTLavavej StephanTLavavej added the bug Something isn't working label Mar 15, 2024
@StephanTLavavej StephanTLavavej self-assigned this Mar 16, 2024
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StephanTLavavej reviewed Mar 19, 2024
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StephanTLavavej commented Mar 19, 2024

I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed.

@StephanTLavavej StephanTLavavej merged commit 7ac8388 into microsoft:main Mar 19, 2024
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StephanTLavavej commented Mar 19, 2024

☢️ 🛠️ 😻

@AlexGuteniev AlexGuteniev deleted the sulfur branch March 19, 2024 22:04
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Successfully merging this pull request may close these issues.

<atomic>: With _STD_ATOMIC_ALWAYS_USE_CMPXCHG16B defined to 1, atomic_ref<16 bytes> does not report is_lock_free and is_always_lock_free correctly

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