Re: [Haskell-beginners] Integer performance of GHC

I just tried the LLVM code generator from GHC HEAD. I must say I am impressed. Now my simple MD5 is just 1.8 times slower, rather 2.77. Still not as efficient as I would like, but hey... I'll have a look at the generated assembly. 2010/8/7 Sebastián E. Peyrott :

Thanks for the links. I had already seen Don's post, but I have yet to try the LLVM backend. I'll do so as soon as a stable GHC version with it is out.

The Haskell math performance link is interesting. If I'm not mistaken, the OP achieved C levels of performance by switching to Data.Vector and keeping data structures as close to C as possible. That seems reasonable. However, for the example I gave earlier (an MD5 implementation), I don't see a way to use Data.Vector. The algorithm performs repeated operations on 4 32-bit integers and that's it. The implementation in Happstack is as close to C as possible, yet it's still slower. My own too.

I've been trying to read the generated Core and assembly but I don't really have any experience doing that. I can see most fields are unboxed and inlining appears to be working. I see repeated calls to GHC.Prim.narrow32Word# too. In the generated assembly I see many operations with literal '$4294967295'. Could that be the culprit?

I have uploaded the generated Core for the main MD5 computation (RFC1321, section 3.4) here: http://pastebin.com/e51njdcS The actual computation starts at line 1507. Please note this is not from the version in Happstack but rather from my own. You can find RFC1321 here: http://tools.ietf.org/html/rfc1321

If you feel talking about Core and assembly is perhaps not suitable for Haskell-beginners, I'll move this discussion to Haskell-cafe.

Thanks.

2010/8/7 David Virebayre :

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2010/8/7 Sebastián E. Peyrott :

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Hi, I'm looking for information on Haskell's viability for heavy integer math. My (very) naive tests show Haskell lagging behind C even

Relevant links :

Benefits of the LLVM code generator (lots of other relevant posts on Dons' blog) http://donsbot.wordpress.com/2010/02/21/smoking-fast-haskell-code-using-ghcs...

Archive of threads about loop unrolling : http://www.haskell.org/pipermail/glasgow-haskell-users/2009-March/thread.htm...

(Also check some of the links in "You might also be interested in:") http://efreedom.com/Question/1-2978979/Haskell-math-performance

David.