On Wed, Sep 23, 2015 at 07:09:43PM -0400, Michael Meissner wrote:
> On Tue, Sep 22, 2015 at 01:43:55PM -0400, David Edelsohn wrote:
> > On Tue, Sep 22, 2015 at 1:39 PM, Bernhard Schommer
> > <bernhardschom...@gmail.com> wrote:
> > > Hi,
> > >
> > > if been working with the windriver Diab c compiler for 32bit ppc for and
> > > encountered an incompatibly with the eabi version of the gcc 4.83. When
> > > calling functions with more than 8 float arguments the gcc stores the 9th
> > > float argument (and so on) as a float where as the diab compiler stores
> > > the
> > > argument as a double using 8 byte.
> > >
> > > I checked the EABI document and it seems to support the way the diab
> > > compiler passes the arguments:
> > >
> > > "Arguments not otherwise handled above [i.e. not passed in registers]
> > > are passed in the parameter words of the caller=E2=80=99s stack frame.
> > > [...=
> > > ]
> > > float, long long (where implemented), and double arguments are
> > > considered to have 8-byte size and alignment, *with float arguments
> > > converted to double representation*. "
> > >
> > > Does anyone know the reason why the gcc passes the argument as single
> > > float?
> >
> > Hi, Bernhard
> >
> > First, are you certain that you have the final version of the 32 bit
> > PPC eABI? There were a few versions in circulation.
> >
> > Mike may remember the history of this.
>
> Well I worked on it around 1980 or so.
You worked on PPC 10 years before the first Power systems were
announced?
Amazing foresight :-)
> I don't remember the details (nor do I
> have the original manuals I was working from). From this distance, it sure
> looks like a bug, but I'm not sure whether it should be fixed or
> grand-fathered
> in (and updating the stdargs.h support, if this is the offical calling
> sequence).
Gabriel
