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https://issues.apache.org/jira/browse/LUCENE-3179?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13045659#comment-13045659
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Dawid Weiss commented on LUCENE-3179:
-------------------------------------
I posted the benchmarks of intrinsic vs. manual (OpenBitSet) performance of nlz
and pop (bitcount) methods a while ago -- they should still be around JIRA
somewhere. If I recall right, the difference was significant, although not like
an order of magnitude or something... and on CPUs without intrinsic
instructions the implementation handcrafted by Yonik was actually faster than
the one in the standard library. Of course these days most CPUs will have
popcnt/ nlz instructions, so it makes sense to switch.
> OpenBitSet.prevSetBit()
> -----------------------
>
> Key: LUCENE-3179
> URL: https://issues.apache.org/jira/browse/LUCENE-3179
> Project: Lucene - Java
> Issue Type: Improvement
> Reporter: Paul Elschot
> Priority: Minor
> Fix For: 3.3
>
> Attachments: LUCENE-3179.patch
>
>
> Find a previous set bit in an OpenBitSet.
> Useful for parent testing in nested document query execution LUCENE-2454 .
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