fix(wc):GNU wc-cpu.sh #9144
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fix(wc):GNU wc-cpu.sh #9144
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Add CPU feature detection to conditionally use SIMD-accelerated bytecount functions for chars and lines, falling back to naive methods when SIMD is disabled by environment or unavailable on CPU. Introduce a hidden --debug flag to output SIMD status information, aiding in troubleshooting performance issues.
…lity Swap the if-else blocks in the wc function's debug output to check for SIMD allowance first, improving code flow without changing functionality.
- Add asimd, ASIMD, hwcaps, tunables, TUNABLES to .vscode/cspell.dictionaries/jargon.wordlist.txt - Prevents spellchecker from flagging valid technical terms used in the codebase
CodSpeed Performance ReportMerging #9144 will degrade performances by 2.11%Comparing Summary
Benchmarks breakdown
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RenjiSann
reviewed
Nov 4, 2025
RenjiSann
reviewed
Nov 4, 2025
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We should agree on a common implementation to put in uucore for it to be reused for the --debug flag of cksum (see #9088)
Co-authored-by: Dorian Péron <[email protected]>
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Overview
Disable SIMD-accelerated paths when GLIBC_TUNABLES removes AVX/AVX512 so wc falls back to the naive counters.
Add hidden --debug flag output that reports whether hardware acceleration is active, disabled by tunables, or unavailable at runtime.
Cache SIMD policy decisions and reuse them within the fast path code to avoid repeated environment parsing.
Testing
cargo test -p uu_wc
cargo clippy -p uu_wc -- -D warnings
Spot-check wc -l with and without GLIBC_TUNABLES='glibc.cpu.hwcaps=-AVX2,-AVX512F'