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Re: gcc, march and sse

On Wed, Dec 03, 2008 at 04:26:11PM +0100, Joel Carnat wrote:
> Hello,
> I read that Slackware Linux compiles most of its packages with
> "-march=i486 -mtune=i686". As far as I understood gcc's manpage, this
> means "keep code compatible with 486 CPU but allow the use pentiumpro
> special features", right ?

-march chooses the instruction set used. 

-mtune chooses, under that restriction, the selection and ordering of
instructions used for your program.

E.g., if you have lots of 686 but few 486, you'd use that so that your
program, while running on the 486, will still be a bit better on the 686 
than without.


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