Fix: Initialize dummy_input in simsimd_capabilities to fix MSan false positive#302
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ashvardanian merged 1 commit intoashvardanian:mainfrom Mar 4, 2026
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… positive
`simsimd_capabilities` probes SIMD instructions with an uninitialized
`dummy_input` buffer and `n=0`. SVE implementations use `do { ... } while`
loops that always execute the body once. MemorySanitizer doesn't understand
SVE predicated loads and reports use-of-uninitialized-value.
Initialize the buffer to zero to silence the false positive.
Co-Authored-By: Claude Opus 4.6 <[email protected]>
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Summary
simsimd_capabilitiesprobes SIMD instructions with an uninitializeddummy_inputbuffer andn=0. SVE implementations (e.g.simsimd_cos_f32_sve) usedo { ... } whileloops that always execute the body once. MemorySanitizer doesn't understand SVE predicated loads and reports use-of-uninitialized-value false positives.The fix simply initializes the buffer to zero:
largest_scalar_t dummy_input[1] = {0};Context
Discovered during ClickHouse CI stress testing with MSan on ARM (aarch64).