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Re: [RFC] Linux-specific ppc32 ABI
On Sat, 26 Jan 2008, Mark Kettenis wrote:
> > > GCC (XLC as well) doesn't promote floats to doubles and does not align
> > > them to 8 bytes in the stack. Actually, it just aligns the prototyped
> > > float parameters to 4 bytes in the stack.
>
> So both compilers are buggy.
They would be buggy if they were targetting PowerPC Solaris from 1995 and
if the 1995 ABI from Sun is an accurate description of the ABI on that
system in the first place. They are not targetting that OS, they are
targetting OSes where the 1995 document is only indicative guidance to a
predecessor of the ABIs in use on those OSes.
> > > This is something that needs to be improved in the ABI text.
>
> Well, I suppose you can change it, but I wouldn't call it an
> improvement. Who controls the 32-bit PowerPC SystemV ABI these days?
The Power.org ABI working group, which is working on producing a
copyright-clean document (so not using any of the Sun text), copyrights to
be assigned to the Linux Foundation, describing the ABIs (both hard and
soft float, and E500 and Altivec extensions) as they are in use today for
both GNU/Linux and bare-metal (EABI) targets (GNU/Linux and EABI differ in
the default for -maix-struct-return, and in the default size of long
double, but are otherwise the same at the function-call level).
--
Joseph S. Myers
joseph@codesourcery.com