rawhide report: 20050510 changes

dragoran dragoran at feuerpokemon.de
Fri May 13 14:15:42 UTC 2005


Nils Philippsen wrote:

>On Tue, 2005-05-10 at 11:30 -0400, Owen Taylor wrote:
>  
>
>>On Tue, 2005-05-10 at 08:26 -0400, Jakub Jelinek wrote:
>>
>>    
>>
>>>a) on x86-64 this is unnecessary, all x86-64's have -msse2 by default
>>>b) -msse2 implies -msse
>>>c) if you use -msse2 in CFLAGS for all files, you can't run the latest
>>>   GIMP on e.g. Pentium2, or pre-x86_64 AMD chips.
>>>   -msse2 should be ONLY used on sources that have SSE/SSE2 stuff in it,
>>>   and GIMP should make sure that no routine from those sources will be
>>>   ever called on pre-SSE2 chips
>>>      
>>>
>>This sounds like a big pain ... shouldn't there be a way to say 
>>"use sse2/sse only for builtins" ? 
>>
>>Without that, there is no way to use builtins in single functions; you
>>need to have one file for sse2, one for sse, one for mmx, and do the
>>detection of the current processor somewhere else entirely.
>>    
>>
>
>I concur, with gcc <= 4.0.0-2 it was possible to use MMX/SSE calls in
>inline assembly without having to use -mmmx/-msse/-msse2. In order to
>build the gimp so that it uses MMX/SSE where available, I had to resort
>to serious autofoo munging because it doesn't allow for setting
>per-object compiler flags.
>
>Nils
>  
>
why aren't sse/mmx/sse2 enabled by default on x86_64 ? all those chips 
supports it.




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