RE: GCC: Inefficient register usage?

["Mark Powell" <medp at primag dot co dot uk>]

Hm, so the volatile issue is not related to the deterioration in
optimisation.
Unfortunately, I had to upgrade to the gcc 2.95 series to get support for
ColdFire which we are now using as well as 68030.


> -----Original Message-----
> From: crossgcc-owner@sources.redhat.com
> [mailto:crossgcc-owner@sources.redhat.com]On Behalf Of Uvarov Sergey
> Sent: 25 August 2000 11:30
> To: crossgcc@sourceware.cygnus.com
> Subject: RE: GCC: Inefficient register usage?
> Importance: High
>
>
> I'm still using gcc 2.7.2.3 and quite happy with it. But it produces the
> same ugly code for the Christopher's example:
>
>         moveb -2:w,d0
>         orb #64,d0
>         moveb d0,-2:w
>
> So I think that the problem existed before the EGCS initiative. Look for
> Kai Ruottu's letter "volatile again" from 27 Jan 2000 to get more
> information.
>
> 	Sergey
>
> On Fri, 25 Aug 2000, Mark Powell wrote:
>
> > I have noticed a definite worsening of gcc's optimisation for the m68k
> > target (and related targets such as ColdFire) since the EGCS initiative,
> > i.e. versions since 2.8. I guess it is due to reworkings of the gcc
> > internals to produce better code for the Pentiums and Sparcs. I
> remember one
> > large piece of work in the early days of EGCS was the "Haifa
> scheduler". I
> > don't know what it effect it might have had, but something like
> that may be
> > the cause of the deterioration in 68k optimisation.
> >
> > I wonder if there is any switch to revert to older behaviour.
> Any GCC gurus
> > out there able to comment?
> >
>


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