register indirect addressing for global variables on powerpc

[Andrew Pinski]

On Sun, Jan 13, 2013 at 11:00 PM, Thomas Baier <baier@microsys.de> wrote:
> Dear list,
>
> I've just subscribed to the list and I hope this is the right place for
> the following question.
>
> The operating system I'd like to use gcc for (OS-9, for the curious)
> requires an ABI, where global variables are only accessed through
> register indirect addressing. On the powerpc platform, r2 is used for
> indirect addressing. There is already a feature in gcc which can use
> register indirect addressing for the powerpc target for global variables
> using a special small data area, but unfortunately this is not enough.
>
> Currently I'm a bit lost in where to start reading to get an idea how I
> could add this new ABI to gcc. Can you please point me to some reading
> or maybe even share some ideas how this could be accomplished?

The Mac OS 9 ABI is very similar to the AIX ABI.  So you should be
able to start with the AIX ABI and go from there.

Thanks,
Andrew