8000 perf: special-case pow(2, n) with shl by DaniPopes · Pull Request #475 · recmo/uint · GitHub
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perf: special-case pow(2, n) with shl #475

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perf: special-case pow(2, n) with shl #475

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@DaniPopes DaniPopes commented May 28, 2025 •
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Check self==2 in pow, returning 1<<exp instead of looping.

This also fixes Shl and Shr impls for Uint with Uint: the code was using limbs[0] without checking that the other limbs are 0. Extracted to #476.

@DaniPopes DaniPopes requested a review from prestwich as a code owner May 28, 2025 23:43
@DaniPopes DaniPopes force-pushed the pow-2-by-n branch 3 times, most recently from 668df59 to a203841 Compare May 29, 2025 00:29
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codspeed-hq bot commented May 29, 2025 •
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CodSpeed Performance Report

Merging #475 will degrade performances by 23.61%

Comparing DaniPopes:pow-2-by-n (7ec9f59) with main (51f9ce6)

Summary

⚡ 3 improvements
❌ 8 regressions
✅ 242 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

Benchmark BASE HEAD Change
❌ log/192 11.8 ms 13.7 ms -13.65%
❌ log/256 14.3 ms 16.2 ms -11.61%
❌ log/384 21.1 ms 23.5 ms -10.41%
❌ overflowing_pow/192 1.1 ms 1.4 ms -18.64%
❌ overflowing_pow/256 2 ms 2.3 ms -14.06%
❌ overflowing_pow/384 4.5 ms 5.1 ms -12.23%
❌ overflowing_pow/4096 1.8 ms 2.3 ms -23.61%
⚡ overflowing_pow/64 79.4 µs 35.6 µs ×2.2
⚡ root/127/128/128 9.8 ms 5.6 ms +76.88%
⚡ root/127/192/192 16.1 ms 11.8 ms +36.85%
❌ root/127/256/256 12.2 ms 13.8 ms -11.89%

@DaniPopes DaniPopes force-pushed the pow-2-by-n branch 3 times, most recently from 599372d to aa7bd46 Compare May 29, 2025 00:55
@prestwich prestwich enabled auto-merge May 29, 2025 14:36
@DaniPopes DaniPopes marked this pull request as draft May 29, 2025 14:37
auto-merge was automatically disabled May 29, 2025 14:37

Pull request was converted to draft

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@prestwich prestwich prestwich approved these changes

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