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Re: Which optimization levels affect gimple?
On Sun, Jan 28, 2007 at 11:02:10PM +0000, Paulo J. Matos wrote:
> On 24 Jan 2007 09:56:55 -0800, Ian Lance Taylor <iant@google.com> wrote:
> >At present, as far as I know, the highest defined optimization level
> >is -O3. -ONUMBER where NUMBER > 3 is equivalent to -O3. There is no
> >particular guarantee that will remain true in the future, although
> >there are also no current plans to change it.
>
> That's quite curious. I always thought that O3 was different to O4,
> O5, ... O9. Still, beyond O3 optimizations were not safe... maybe an
> old gcc myth! :-)
Back in the late 90s, there was a fork of gcc that tried to optimize
specifically for the Pentium ("586" flavor, specifically), and it had
levels going up to -O6 that were distinct.
AFAIK, there was never an FSF or egcs release where -On for n>3 meant
anything.