Changing CFLAGS for i386 packages on x86_64

[dragoran]

Arjan van de Ven wrote:
>> On x86_64 it wont hurt enabling i686 (cmov) and see2 because all x86_64 
>> cpus support this instructions.
>>     
>
> enabling cmov actually will hurt because it often ends up being slower
> than without ;)
>
>   
first time I hear this, did I miss something?... any benchmarks or links 
showing this?
and what about see2?