-mtune=generic for i386 backend

[Jan Hubicka]

> Jan Hubicka wrote:
> 
> > + "virtual CPU" can not be used as @option{-march} operand. In 64-bit mode
> > + @option{x86-64} shall be used instead. 
> 
> s|shall|should
> 
> In 32-bit mode the @option{i686} is
> > + available for i686 familly chips (instruction set of PentiumPro and tunning
> 
> family
> 
> I think you should also add some language to indicate that the behavior
> from -mtune=generic might change in future.  Ten years from now,
> -mtune=generic will generate code tuned for whatever x86 is most popular
> then, not the ones that are popular now.

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?

Honza