Fix MSan false positive in SimSIMD capability probing#98699
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alexey-milovidov merged 2 commits intomasterfrom Mar 4, 2026
Merged
Fix MSan false positive in SimSIMD capability probing#98699alexey-milovidov merged 2 commits intomasterfrom
alexey-milovidov merged 2 commits intomasterfrom
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`simsimd_capabilities` probes SIMD instructions with an uninitialized buffer
and `n=0`. The SVE implementation of `simsimd_cos_f32_sve` uses a
`do { ... } while` loop that always executes once. MSan doesn't understand
SVE intrinsics and reports use-of-uninitialized-value false positives.
Initialize `dummy_input` to zero to silence the report.
https://s3.amazonaws.com/clickhouse-test-reports/json.html?PR=98677&sha=781b465ce87c2bb0bb1f3080b443c4290b383682&name_0=PR&name_1=Stress%20test%20%28arm_msan%29
Co-Authored-By: Claude Opus 4.6 <[email protected]>
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Workflow [PR], commit [8e22b40] Summary: ❌
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Point to the merged ClickHouse/v6.5.1 branch which includes the initialization of `dummy_input` in `simsimd_capabilities`. ClickHouse/SimSIMD#10 Co-Authored-By: Claude Opus 4.6 <[email protected]>
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Needed for #98677 |
Algunenano
approved these changes
Mar 4, 2026
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LGTM. Upstream PR is created too
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Summary
dummy_inputbuffer to zero insimsimd_capabilities(SimSIMD submodule)n=0. The SVE implementation ofsimsimd_cos_f32_sveuses ado { ... } whileloop that always executes once. MSan doesn't understand SVE intrinsics and reports use-of-uninitialized-value false positives.CI report: https://s3.amazonaws.com/clickhouse-test-reports/json.html?PR=98677&sha=781b465ce87c2bb0bb1f3080b443c4290b383682&name_0=PR&name_1=Stress%20test%20%28arm_msan%29
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