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Expose popcount #10212

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polux opened this issue Apr 25, 2013 · 2 comments
Closed

Expose popcount #10212

polux opened this issue Apr 25, 2013 · 2 comments
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area-core-library SDK core library issues (core, async, ...); use area-vm or area-web for platform specific libraries. closed-duplicate Closed in favor of an existing report library-core type-enhancement A request for a change that isn't a bug

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@polux
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polux commented Apr 25, 2013

Most CPUs have a popcount (http://en.wikipedia.org/wiki/Hamming_weight) instruction but it is not accessible in Dart.

Yet certain algorithms and datastructures rely on it (http://en.wikipedia.org/wiki/Hash_array_mapped_trie for instance).

So far I have used software emulations of popcount but it's a pain because
  1. it's potentially slower than a C++ version and definitely slower than a CPU instruction
  2. I don't know any fast implementation that works on both 32 and 64 bits architectures

Would it be possible to expose it as a method of int or num? (With a fallback to a C++ version in the VM for CPUs that don't support it and a software version in dart2js.)
@rakudrama
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See also Issue #5798, Issue #6486.

Added Area-Library, Library-Core, Triaged labels.

@floitschG
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Added this to the Later milestone.
Added Duplicate label.
Marked as being merged into #5798.

@polux polux added Type-Enhancement area-core-library SDK core library issues (core, async, ...); use area-vm or area-web for platform specific libraries. library-core closed-duplicate Closed in favor of an existing report labels Apr 30, 2013
@polux polux added this to the Later milestone Apr 30, 2013
@floitschG floitschG mentioned this issue Jun 3, 2015
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@kevmoo kevmoo added type-enhancement A request for a change that isn't a bug and removed type-enhancement labels Mar 1, 2016
This was referenced Jun 10, 2023
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area-core-library SDK core library issues (core, async, ...); use area-vm or area-web for platform specific libraries. closed-duplicate Closed in favor of an existing report library-core type-enhancement A request for a change that isn't a bug
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