Remove unrolling of last iteration of loop for x86 decode#80
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lemire merged 2 commits intoApr 30, 2026
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It is not clear why this was originally done. There is no comment in the source code, but it does not seem to improve performance.
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@andrewthad Isn't this PR doing an extra memcpy? |
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Good catch. I've made this change in the latest commit. I had forgotten that, without the unrolled final iteration, there was no need to load the keys for iteration N+1 at the beginning of iteration N. I've run the perf test again, and this further does not have any measurable impact, but it is a nice further simplification. |
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Verified manually. This does not seem to affect performance. Merging. |
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It is not clear why this was originally done. There is no comment in the source code, but it does not seem to improve performance.
If I run the perf benchmark on my laptop and bump the iterations up to 5000 from 100, I do not see any measurable difference.