2.8 gcc on m68k

Robin Kirkham Robin.Kirkham@mlb.dmt.csiro.au
Thu Feb 26 20:47:00 GMT 1998

Someone said (I've lost the original):

> > I noticed that a particular set of operations was slower in the new 2.8
> > compiler.  Does anybody know what could be done to get back the
> > speed, and still have the 68060 support?
> >
> > It appears that in general
> > move rX(nn), rX(mm)
> > has been replaced with
> > move rX(nn), rY
> > move rY, rX(mm)
> Sounds to me like one of the ColdFire mods has escaped. I know that that
> that particular combination of instructions is illegal on the ColdFire
> architecture and that a lot of the m68k.md was modified between 2.7.1 and
> 2.8.

That's peculiar: I don't think I've observed any change in 68k code between
gcc-2.7.1 and egcs-1.0.1 (which is substantially based on gcc-2.8, and
includes the ColdFire support). Do you have a small test case that isolates
the problem?

Robin Kirkham			CSIRO Manufacturing Science and Technology
Project Engineer		Locked Bag 9, Preston 3072, Australia
robin.kirkham@mlb.dmt.csiro.au	Phone: +61 3 9662-7756  Fax: +61 3 9662-7851

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