Re: [RFC] PPC64: Vector Function ABI for Power Architecture

[GT <tnggil at protonmail dot com>]

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Friday, November 22, 2019 4:45 PM, Bill Schmidt <wschmidt@linux.ibm.com> wrote:

> On 11/22/19 2:58 PM, GT wrote:
>
> > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
> > On Friday, November 22, 2019 3:34 PM, Bill Schmidt wschmidt@linux.ibm.com wrote:
> >
> > > On 11/22/19 2:27 PM, Tulio Magno Quites Machado Filho wrote:
> > >
> > > > GT tnggil@protonmail.com writes:
> > > >
> > > > > 1.  The document is hosted at URL: https://github.com/power8-abi-doc
> > > > > 2.  Bill Schmidt, cc'ed here, is the IBMer ultimately responsible for the document.
> > > > >
> > > > > The pdf does not render quite right - so for feedback regarding visual presentation of the document, first download the html and open it in a browser. Please use the ABI's rendering in a browser as the basis for any recommendations on its formatting.
> > > > > In section "Vector Function Name Mangling", I'm afraid we can't leave the <isa>
> > > > > with an entry as generic as VSX.
> > > > > There are VSX instructions included in ISA 3.0 that will not execute in ISA
> > > > > 2.07. So, I think we need 2 <isa> entries there:
> > > >
> > > > 1.  ISA 2.07, which is the minimum ISA required in this document.
> > > > 2.  ISA 3.0
> > > >     We have not used any instructions introduced in ISA 3.0. Can I simply have a single
> > > >     entry indicating ISA 2.07? Or should it be ISA 2.07+ (i.e. ISA at or above v2.07)?
> > > >     Or do we still really need 2 separate entries?
> > > >
> >
> > Thanks.
> > Bert.
>
> ABI decisions shouldn't be based only on the current implementation. 
> It's possible that we would later want to make use of ISA 3.0
> instructions in a future implementation of these same interfaces. 
> Furthermore, it becomes even more likely as we move ahead into later
> versions of the ISA.  So I think it's best to be flexible and assign
> 2.07 and 3.0 today, with the understanding that we will continue to add
> to this as ISA levels are released.
>
> For today's implementations, the VSX/2.07 mangling would be the only one
> in use, so we're not asking for any changes in the implementation.
>
> Thanks!
> Bill

Alright. I will have the assignments as:
'b' VSX as defined in Power ISA v2.07
'c' VSX as defined in Power ISA v3.0

Good enough?

Thanks.
Bert.