Re[5]: [Haskell-cafe] Re: speed: ghc vs gcc

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 fair?

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@gmail.com

On Sat, Feb 21, 2009 at 5:21 PM, Bulat Ziganshin 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@gmail.com

-- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com