Re: Proposal: Add Data.Bits.popCount

If someone wanted to spruce up my patch here http://hackage.haskell.org/trac/ghc/ticket/3489 to include the GMP popcount call, so that we can make the Integer instance of Bits work efficiently with the new call, that might also help this proposal. But yeah, even if not, +1. On Wed, Aug 17, 2011 at 4:33 PM, Johan Tibell wrote:

On Wed, Aug 17, 2011 at 7:44 PM, Maciej Marcin Piechotka wrote:

...

I posted bug for various similar instructions some time ago:

http://hackage.haskell.org/trac/ghc/ticket/4102

Probably the update should be done in batch (i.e. popCount, trailing/leading zeros etc.)

I'd be happy to see these as well. If someone would like to do the GHC work needed to have them translate into single machine instructions where available, have a look at the implementation of the popCnt# primops here:

https://github.com/ghc/ghc/commit/2d0438f329ac153f9e59155f405d27fac0c43d65

https://github.com/ghc/packages-ghc-prim/commit/cefc19afafe5107ff98d5205c204...

https://github.com/ghc/testsuite/commit/2f4d13348e2140f7fc0d4b8b995a2be0fa62...

I don't have time to do so at the moment.

I'd prefer to not wait with adding popCount until this is done, unless someone takes it on them to add the others before GHC 7.4.

-- Johan

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