Re: -mtune=generic for i386 backend

[Mark Mitchell <mark at codesourcery dot com>]

Jan Hubicka wrote:

> I wanted to express this by "is supposed to envolve in future versions
> of GCC as new CPU models are introduced and other become obsolette.".
> Since my english is poor, perhaps you can suggest better wording?

Actually, your English is very good, and a heck of a lot better than my
Czech!  Your spelling needs a little work though; you might try M-x
ispell-region in your friendly local emacs. :-) :-)

I've taken the liberty of reworking your paragraph.

"Produce code optimized for the most common IA32/AMD64/EM64T processors.
   If you know the CPU on which your code will run, then you should use
the corresponding @option{-mtune} option instead of
@option{-mtune=generic}.  But, if you do not know exactly what CPU users
of your application will have, then you should use this option.

As new processors are deployed in the marketplace, the behavior of this
option will change.  Therefore, if you upgrade to a newer version of
GCC, the code generated option will change to reflect the processors
that were most common when that version of GCC was released.

There is no @option{-march=generic} option because @option{-march}
indicates the instruction set the compiler can use, and there is no
generic instruction set applicable to all processors.  In contrast,
@option{-mtune} indicates the processor (or, in this case, collection of
processors) for which the code is optimized."

Your patch is OK with that change, if you like the paragraphs I wrote. :-)

-- 
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713