[Haskell-cafe] Re: speed: ghc vs gcc

Bulat Ziganshin bulat.ziganshin at gmail.com
Sat Feb 21 18:35:29 EST 2009

Hello Louis,

Sunday, February 22, 2009, 2:30:23 AM, you wrote:

yes, you are right. Don also compared results of 64x-reduced
computation with full one. are you think that these results are more

> Observation:

> The best gcc result shown in the thread, if I recall, precomputed
> the result of the full computation at compiletime and simply
> outputted it, when we looked at the assembly.

> While I will accept that this could be seen as an optimization GHC
> should have made, I do not accept that this will be the case with
> most everyday code a programmer writes, as most code is not used to
> simply compute arithmetic constants.
> For code that actively requires computation at runtime, I have seen
> no examples of an instance where well-optimized GHC is actually
> dozens or hundreds of times slower than GCC output.

> Louis Wasserman
>  wasserman.louis at gmail.com

> On Sat, Feb 21, 2009 at 5:21 PM, Bulat Ziganshin
> <bulat.ziganshin at gmail.com> wrote:
>  Hello Louis,

>  Saturday, February 21, 2009, 4:16:10 AM, you wrote:
 >> In the meantime, a brief summary:
> a minor correction: the best gcc result shown in the thread was 50x
>  faster than Don's one, so you need to miltiple all ratios by a factor
>  of 50

 >> Straightforward and simple Haskell code, written by an individual
 >> aware of issues with tail recursion and stream fusion, is frequently
 >> within 3x the speed of GCC code when compiled with appropriate
 >> optimizations in GHC.
> yes, within 150x margin

 >> When performance is an absolute necessity,
 >> Haskell code can sometimes be manually modified (e.g. with manual
 >> loop unrolls) to equal GCC in performance.
> yes, to make it only 50x slower while being only 7 times larger (i
>  mean source lines)
 >> Can we move on?
>  yes, we can! :)
>  --
>  Best regards,
>   Bulat                            mailto:Bulat.Ziganshin at gmail.com


Best regards,
 Bulat                            mailto:Bulat.Ziganshin at gmail.com

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