Template performance

[Emil Madsen]

2010/11/23 Stanislav Blinov <blinov at loniir.ru>

> 23.11.2010 2:23, bearophile wrote:
>
>> Time ago I have found a little C++ program that computes the number of
>> solutions to the N Queens problem at compile-time using just templates. I
>> have translated it into CTFE code and I have shown in this newsgroup that if
>> your purpose is to compute a result at compile-time, then D CTFE allows you
>> to write much simpler (and faster) code compared to the C++ template
>> mataprogramming.
>>
>> This time I have translated that C++ code to D code that uses just
>> templates. This is not idiomatic D code, because for this purpose CTFE is
>> better, but templates are used in D too, so it may be a performance
>> benchmark for templates in general.
>>
>> I am not very good with C++ templates yet, so if you spot an error in my D
>> translation please tell me that I will redo the timings.
>>
>> Compilation time: G++ 0.96 seconds, dmd 12.4 seconds.
>>
>> With N=7 G++ uses about 34 MB RAM, DMD about 130+ MB RAM.
>>
>> I have used MinGW 4.5.1 and DMD 2.050.
>>
>>
> It'd be good if you also posted the machine specs. I ran the benchmark on
> Intel i5 750 with 8Gb RAM under Windows7 Pro x64.
>
> I don't have G++ right now, but I tried cl from Visual Studio 2008 and dmc
> 8.42n instead
>
> Here are the timings (compiler-version-seconds):
>
> dmd 2.050            2.97958
> cl  15.00.30729.01   3.65038
> dmc 8.42n            11.6375
>
> So at least on this system dmd doesn't look that bad at all.
>

I'm getting:
MinGW G++ (source code modified):  744 miliseconds
MinGW G++ (usual version):   924 miliseconds
Dmd:      4275 miliseconds
(i7 720QM, 4GB ram)

-- 
// Yours sincerely
// Emil 'Skeen' Madsen
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