[Haskell-cafe] performance issues with popCount

Nicolas Trangez nicolas at incubaid.com
Fri Sep 7 13:54:55 CEST 2012

On Thu, 2012-09-06 at 12:07 -0700, Johan Tibell wrote:
> Have a look at the popCount implementation for e.g. Int, which are
> written in C and called through the FFI:
> https://github.com/ghc/packages-ghc-prim/blob/master/cbits/popcnt.c 

Out of interest: isn't this compiled into the popCnt# primop (and popcnt
instruction on SSE4.2)?

I recently noticed Data.IntSet also contains a fairly basic "bitcount"
implementation [1]. Is this kept as-is for a reason, instead of using
popCount from Data.Bits?



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