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

Bulat Ziganshin bulat.ziganshin at gmail.com
Fri Feb 20 19:16:33 EST 2009

Hello Sebastian,

Saturday, February 21, 2009, 2:42:33 AM, you wrote:

> Bulat, please, you're missing the point.

actually you are missing the point. i mirror Don's
"non-attacking" style of comments on my person. are you mentioned
those Don letter? sure - no

> Nobody is saying that the
> template-haskell trick was somehow a viable general strategy right
> now that everyone should use by default. It was used as a
> proof-of-concept that a simple technique can lead to massive
> performance improvements - and we get numbers for how massive it
> would be (beating gcc for this benchmark).

sorry, but you was fooled too. the situation was the following: i
wrote non-optimal code for 64-bit platforms (using 32-bit int) and Don
don't corrected it. then he compiled TH-generated code via *gcc* that
used "fusion" technique - the same that was used by 32-bit C++ code

are you wondered why -D64 version is 8 times faster than -D8 one? it's
exactly because *gcc* reduced 64 additions to just one operation. so
this "fair" comparison used TH+gcc to generate faster code than gcc
with improper data type definitions. if Don will fix C++ program, he
will find that it's speed reduced in the same proportion - without TH

> This isn't about "faking" a benchmark, it's about investigating the
> reasons for why the benchmark looks they way it does, doing testing
> to verify the assumptions (in this case using TH), and making
> constructive suggestions (add loop-unrolling to the compiler). This
> investigation tells us that in this case a compiler could beat gcc,
> if only it were to do loop unrolling in the way the TH code does. That's a result!

yes, in the cases when *gcc* "fuse" loops and you don't allow it do it
for C++ code but allows for Haskell - you will win

> I would ask you to note the simple fact that every single
> constructive message in this thread has come from people other than
> you.

you are ignore, though, the fact that every destructive message in
this thread comes against me. it seems that it's a crime here to write
about ghc speed anything but praise. in best case people will said
that these tests are destructive :lol:

> I hope this leads you reconsider your tone and general approach
> in the future. Haskell people in general are always pretty good at
> accepting criticism IME (they tend to want to fix the problem),

that criticism??? cows can't fly, and ghc cannot beat gcc in 2
months. that bothers me is people that attack me just for comparing
compilers head-to-head

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

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