Newsgroups, off-topic

[Steven Schveighoffer]

On Sat, 24 Apr 2010 05:32:25 -0400, Joseph Wakeling  
<joseph.wakeling at webdrake.net> wrote:

> Steven Schveighoffer wrote:
>> I did a little review of the code, I concur that the code is pretty
>> identical, and the D version does not really do any extra allocation.  I
>> found one place where you were using pow(x, 2) to square something in
>> the D version but doing it with simple multiplication in the C++
>> version, but that didn't account for any slowdowns when fixed.  I also
>> saw some places where you write 0 to arrays several times, but removing
>> those didn't help either.
>
> Not several times superfluously?  I think I would be embarrassed if that
> were true :-P

Hm... I hate to embarrass you :)

I found it while manually inlining some functions (to try and see if that  
helps speed it up).  So it wasn't obvious until I saw the two lines  
together.

In Yzlm.objectReputationUpdate, you zero out reputationObject array, then  
call super.opCall, which also zeros out reputationObject.

It's understandable that this got introduced in the D version, you are  
doing something quite different than in the C++ version, swapping with  
another array and you were just being thorough.  I wouldn't be too  
embarrassed, and I note that it doesn't affect the runtime significantly  
anyways.

>> In spite of all this, I still remain convinced that there is nothing
>> inherently bad about these results, D compilers can and probably will
>> get better at optimizing code.  That it doesn't beat a compiler which
>> has been in production/mainstream for many more years probably shouldn't
>> be surprising to any of us, even though we want D compilers to perform
>> the best.
>
> Completely agree here.  I was concerned based on early experience that I
> was doing 'un-D-ish' things that were screwing performance, but now I'm
> fairly confident that I can write OK D code.  From now on it will be all
> pleasure as the compilers speed things up ... :-)
>
> Thanks and best wishes,

Good luck to you too!

-Steve