Re: Passing the complex args in the GPR's

[Umesh Kalappa <umesh.kalappa0@gmail.com>]

Hi Adnrew,
Thank you for the quick response and for PPC64 too ,we do have
mismatches in ABI b/w complex operations like
https://godbolt.org/z/bjsYovx4c .

Any reason why GCC chose to use GPR 's here ?

~Umesh

On Tue, Jun 6, 2023 at 8:28 PM Andrew Pinski <pinskia@gmail.com> wrote:
>
> On Tue, Jun 6, 2023 at 7:50 AM Umesh Kalappa via Libc-alpha
> <libc-alpha@sourceware.org> wrote:
> >
> > Hi all ,
> >
> > For the test case https://godbolt.org/z/vjs1vfs5W ,we see the mismatch
> > in the ABI b/w gcc and clang .
> >
> > Do we have any supporting documents that second the GCC behaviour over CLANG ?
> >
> > EABI states like
> >
> > In the Power Architecture 64-Bit ELF V2 ABI Specification document
> > (v1.1 from 16 July 2015)
>
> You are looking at the wrong ABI document.
> That is for the 64bit ABI.
> The 32bit ABI document is located at:
> http://refspecs.linux-foundation.org/elf/elfspec_ppc.pdf
>
> Plus the 32bit ABI document does not document Complex argument passing
> as it was written in 1995 and never updated.
>
> https://www.nxp.com/docs/en/reference-manual/E500ABIUG.pdf does not
> document it either.
>
> Thanks,
> Andrew Pinski
>
> >
> > Page 53:
> >
> > Map complex floating-point and complex integer types as if the
> > argument was specified as separate real
> > and imaginary parts.
> >
> > and in this case the double complexes are broken down with double real
> > and double img and expected to pass in FPR not the GPR.
> >
> >
> >
> > Thank you
> > ~Umesh