Update SimSIMD to fix MSan false positives from SIMD intrinsics#98807
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alexey-milovidov merged 1 commit intomasterfrom Mar 6, 2026
Merged
Update SimSIMD to fix MSan false positives from SIMD intrinsics#98807alexey-milovidov merged 1 commit intomasterfrom
alexey-milovidov merged 1 commit intomasterfrom
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MSan cannot track initialization through SIMD intrinsics (SVE, NEON, SSE, AVX), causing false-positive "use-of-uninitialized-value" reports in `simsimd_cos_f32_sve`. Added `__msan_unpoison` calls after every dispatch macro to mark results as initialized. https://s3.amazonaws.com/clickhouse-test-reports/json.html?PR=98677&sha=7d4c987f3c650a78b950b264d2676b8b7bc0979e&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 [1e59133] Summary: ❌
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As we now have conflict with #98807
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Summary
__msan_unpoisoncalls after every SIMD dispatch macrosimsimd_cos_f32_sve__msan_unpoison; compiles to no-op in non-MSan buildsCI report: https://s3.amazonaws.com/clickhouse-test-reports/json.html?PR=98677&sha=7d4c987f3c650a78b950b264d2676b8b7bc0979e&name_0=PR&name_1=Stress%20test%20%28arm_msan%29
Upstream PR: ashvardanian/NumKong#304
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Changelog entry
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Note
Medium Risk
Submodule bump in a performance-critical SIMD dependency could subtly affect numerical behavior or performance, though the intended change is MSan-only
__msan_unpoisonannotations that should be a no-op in normal builds.Overview
Updates the
contrib/SimSIMDsubmodule to an upstream revision that adds MSan-specific__msan_unpoisoncalls after SIMD dispatch macros, reducing false-positive "use-of-uninitialized-value" reports (notably on SVE/NEON/SSE/AVX intrinsics).In non-MSan builds these annotations compile away, so functional impact should be limited to sanitizer behavior while keeping existing SIMD codepaths unchanged.
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