D pointers

Grzegorz Piotr Jaskiewicz gj at kde.org.uk
Sat Oct 1 21:22:31 BST 2005


On Saturday 01 October 2005 20:18, George Staikos wrote:
> On Saturday 01 October 2005 13:57, Thomas Braxton wrote:
> > register pressure doesn't look to be an issue on i386, at least w/ gcc
> > 4.0.1.
>
>   Good to know.  Also good, I should point out, that I didn't jump to any
> conclusion that d-> adds to it.  I just claimed that register pressure
> ('period') is an issue on x86.
Gcc decides on which variable to put in register or not, on usage basically. 
So if you use yer d-> pointer everywhere, like this->, than it goes to 
registry quite obviously. There is also thing called hidden register(s) on 
x86 above Pentium III (at least for Intel). Where CPU decides to keep most 
often used pointers from memory in such registers, and no, it is not memory 
cache. 
So, you shouldn't really be worried. Also it is worth mentioning that future 
is 64bit for both Intel and AMD. Both lines are 64bit now, and in the future 
we will see more and more demand for 64bits. Lack of 3rd party software for 
64bits (flash player, win32 codecs) makes this transition bit slower, but I 
think it's just a matter of 1-2 years. So when KDE4 will be out, our primary 
platform will be x86_64 indeed.

Thanks.
-- 
GJ





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