Re: [PATCH 5/14] i386 / Use early clobber to eliminate rotate indesc

[Zachary Amsden]

Andi Kleen wrote:

> On Wed, Aug 10, 2005 at 09:54:11PM -0700, zach@xxxxxxxxxx wrote:
>  
>
> > Use an early clobber on addr to avoid the extra rorl instruction at the
> > end of _set_tssldt_desc.
> >    
>
> I would suggest to just use C for this. I do this on x86-64 and 
> I don't think there is any reason to use this hard to maintain
> code for it.

This one in particular is non-optimal looking from C because the 
compiler misses the potential for rotation.  But, composing into 
temporaries and then issuing two writes to memory instead of multiple 
writes within the same word could actually get you a better cycle count, 
and that is something GCC just might be able to do :)

Zach
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