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possible speedup by using an SIMD popcount #4

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GoogleCodeExporter opened this issue Jun 25, 2015 · 1 comment

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auto-migrated Priority-Low Type-Enhancement

GoogleCodeExporter commented Jun 25, 2015

The gcc builtin uses a lookup table but it is possible to do better.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36041 - existing gcc bug for 
improving the builtin popcount. 

https://groups.google.com/group/comp.arch/msg/ba28c5dbd47a3bba?dmode=source&outp
ut=gplain&noredirect&pli=1 - this post by Terje Mathisen describes the technique

Original issue reported on code.google.com by dbremner@gmail.com on 17 Oct 2012 at 2:02

The text was updated successfully, but these errors were encountered:

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GoogleCodeExporter commented Jun 25, 2015

Thank you for hints. 
Doesn't look like high priority stuff, but feel free to provide the patch. 
Otherwise we will probably wait for the fix in gcc.

Original comment by p...@google.com on 18 Oct 2012 at 8:58

Added labels: Priority-Low, Type-Enhancement
Removed labels: Priority-Medium, Type-Defect

GoogleCodeExporter added auto-migrated Priority-Low Type-Enhancement labels

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