Review Request: little faster sycoca

[Jaime Torres Amate]

> On Sept. 28, 2011, 8:59 a.m., Josef Weidendorfer wrote:
> > I would expect that the ->constEnd() method completely gets inlined with compiler optimization turned on. So are you sure your change
> > improves anything for a release build? Anything performance related always needs to be backed by numbers from a release build. Numbers from a debug build are useless.

I'll check again, but I think I compile with -O2 -g (RELEASE_DEBUG).In any case, it is a minor improvement compared to the use of QBitArray.count, and the removal of a for loop (I'm checking it this has been this way since the beginning, or if fixing it makes other things faster) as Rolf has pointed.


- Jaime Torres


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On Sept. 27, 2011, 8:42 p.m., Jaime Torres Amate wrote:
> 
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> http://git.reviewboard.kde.org/r/102723/
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> 
> (Updated Sept. 27, 2011, 8:42 p.m.)
> 
> 
> Review request for kdelibs.
> 
> 
> Description
> -------
> 
> Using this way to build a for loop: for (const_iterator it=list.constBegin, end=list.constEnd ; it != end; ++it)
> and replacing the count of bits with the QBitArray method for doing that.
> callgrind says:
> before: 2984 calls to constBegin, 0,00%. 2960531 calls to constEnd, 2.33%
> after: 2921 calls to constBegin, 0,00%. 2921 calls to constEnd, 0.00%
> 
> before: calcDiversity, 55.83%  (debug enabled)
> after: calcDiversity, 14,46%  (debug enabled)
> 
> buildsycoca is still not faster than light, but it is only a four lines patch.
> 
> 
> Diffs
> -----
> 
>   kdecore/sycoca/ksycocadict.cpp 17ed9ac 
> 
> Diff: http://git.reviewboard.kde.org/r/102723/diff/diff
> 
> 
> Testing
> -------
> 
> 
> Thanks,
> 
> Jaime Torres Amate
> 
>

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