haskell/containers — pull request #16 by NicolasT (2012-09-15 16:14:46+00:00)
Title: Popcount

These commits change the "bitcount" function in IntSet/Base.hs to use the "popCount" function from Data.Bits, if available, and add a QuickCheck test to validate the original behaviour is kept as-is. This should compile into popcnt instructions on SSE-capable systems.

Some very simple benchmarking using bench-IntSet and comparing the result shows (surprisingly) small differences (both + and -) between the master branch and this version. I just realized I should check whether my builds are using SSE though...