I'm sure DMC is no faster than DMD here - the problem is the backend optimizer.  Many benchmarks (especially concerning floating point) have shown this.

-[Unknown]


Saaa wrote:
> Did anybody verify DMC being faster?
> I don't have DMC, but my DMD code ran in 2.6s iso more than a minute.
> 
> 
>> As everyone has said, these are problems in DMD and DMC.
>>
>>
> 
> 

I meant GDC :/
The original post reports a more than one minute runtime using DMD,
I can't replicate that (with a reasonable cpu).
Or did I miss something ..

> I'm sure DMC is no faster than DMD here - the problem is the backend optimizer.  Many benchmarks (especially concerning floating point) have shown this.
>
> -[Unknown]
>
>
> Saaa wrote:
>> Did anybody verify DMC being faster?
>> I don't have DMC, but my DMD code ran in 2.6s iso more than a minute.
>>
>>
>>> As everyone has said, these are problems in DMD and DMC.
>>>
>>>
>> 

"Saaa" <empty@needmail.com> wrote in message news:g240q6$14cm$1@digitalmars.com...
>I meant GDC :/
> The original post reports a more than one minute runtime using DMD,
> I can't replicate that (with a reasonable cpu).
> Or did I miss something ..

I think you're on to something.

I get wildly different timings over several runs, and sometimes get a (much) faster time _without_ the -O switch on a P4.

No way should that code be that much slower between DMD and GDC... It's a bug. It's probably an alignment issue, but I wouldn't be surprised to see incorrect results for DMD either.

The OP should post that code and the results as a bug. C++ code with DMC probably wouldn't reproduce it because the D version is using the built-in complex type, which is probably the heart of the bug.

http://d.puremagic.com/issues/enter_bug.cgi

- Dave

>
>> I'm sure DMC is no faster than DMD here - the problem is the backend optimizer.  Many benchmarks (especially concerning floating point) have shown this.
>>
>> -[Unknown]
>>
>>
>> Saaa wrote:
>>> Did anybody verify DMC being faster?
>>> I don't have DMC, but my DMD code ran in 2.6s iso more than a minute.
>>>
>>>
>>>> As everyone has said, these are problems in DMD and DMC.
>>>>
>>>>
>>>
> 

janderson wrote:
> Marco wrote:
>> I have written the code reported below to test execution speed of D in Windows and I have found that the same code is about 10 times slower if compiled using DMD w.r.t. GCD: 1.9 minutes in DMD vs 1.84 seconds in GDC ! Is there perhaps something wrong? why such a difference?
>> Thank you.
>>
>> // begin of file mandel_d1.d
>> /*
>> DMD: dmd -inline -release -O mandel_d1.d
>> GCD: gdc -O3 --fast-math -inline -lgphobos --expensive-optimizations mandel_d1.d
>> */
>>
>> import std.stdio;
>>
>> int main()
>> {
>>  cdouble a, b, c, z;
>>  double mand_re = 0, mand_im = 0;
>>
>>  for (double y = -2; y < 2; y += 0.01) {
>>   for (double x = -2; x < 2; x += 0.01) {
>>    z = (x + mand_re) + (y + mand_im) * 1i;
>>    c = z;
>>    for (int i = 0; i < 10000; i++) {
>>     z = z * z + c;
>>     if(z.re * z.re + z.im * z.im > 4.0) {
>>      break;
>>     }
>>    }
>>   }
>>  }
>>  return 0;
>> }
>> // end of file mandel_d1.d
>> ------------------
>>
>> H:\Codici\Benchmarks> ..\timethis.exe mandel_d1
>>
>> TimeThis :  Command Line :  mandel_d1
>> TimeThis :    Start Time :  Mon Jun 02 11:28:41 2008
>>
>>
>> TimeThis :  Command Line :  mandel_d1
>> TimeThis :    Start Time :  Mon Jun 02 11:28:41 2008
>> TimeThis :      End Time :  Mon Jun 02 11:30:35 2008
>> TimeThis :  Elapsed Time :  00:01:54.234
>>
>> H:\Codici\Benchmarks> ..\timethis mandel_gdc1
>>
>> TimeThis :  Command Line :  mandel_gdc1
>> TimeThis :    Start Time :  Mon Jun 02 11:42:27 2008
>>
>>
>> TimeThis :  Command Line :  mandel_gdc1
>> TimeThis :    Start Time :  Mon Jun 02 11:42:27 2008
>> TimeThis :      End Time :  Mon Jun 02 11:42:29 2008
>> TimeThis :  Elapsed Time :  00:00:01.843
>>
> 
> It would be interesting to compare the ASM produced.  DMD is not that great at floating point, doesn't unroll so well and has a longer startup time then GDC in my experience.
> 
> -Joel

DMD does seem to beat GDC on some tests.  From memory I think its better at integer then GDC.

-Joel

On 2008-06-04 02:49:33 +0200, "Dave" <Dave_member@pathlink.com> said:

> 
> "Saaa" <empty@needmail.com> wrote in message news:g240q6$14cm$1@digitalmars.com...
>> I meant GDC :/
>> The original post reports a more than one minute runtime using DMD,
>> I can't replicate that (with a reasonable cpu).
>> Or did I miss something ..
> 
> I think you're on to something.
> 
> I get wildly different timings over several runs, and sometimes get a (much) faster time _without_ the -O switch on a P4.
> 
> No way should that code be that much slower between DMD and GDC... It's a bug. It's probably an alignment issue, but I wouldn't be surprised to see incorrect results for DMD either.
> 
> The OP should post that code and the results as a bug. C++ code with DMC probably wouldn't reproduce it because the D version is using the built-in complex type, which is probably the heart of the bug.
> 
> http://d.puremagic.com/issues/enter_bug.cgi
> 
> - Dave

Yes I think this is probably a bug, and should be reported.
Maybe actually the unoptimized version is faster.
In any case one should *never* benchmark something that does not print/use something depending on what has been calculated:

1) no way to verify if the calculation was correct
2) some smart compiler might even optimize away the whole calculation (correctly because it is not needed)

In this case it is possible that some bug makes NaNs appear, and depending on the IEEE compliance settings of the processor NaNs might slow down the calculation very much (I saw a factor 100 in some calculations).

Fawzi