[RFC PATCH v1 1/1] PPC64: Implement POWER Architecture Vector Function ABI.

GT tnggil@protonmail.com
Tue Aug 18 19:14:19 GMT 2020


‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Monday, August 17, 2020 5:28 PM, Segher Boessenkool <segher@kernel.crashing.org> wrote:

> On Mon, Aug 17, 2020 at 05:44:46PM +0000, GT wrote:
>
> > > This is about the Power binding to some OpenMP API, right? It has
> > > nothing to do with "vector" or "ABI" -- we have vectors already, and
> > > we have ABIs already, more than enough of each.
> > > It is very very VERY hard to review this without being told the proper
> > > setting here.
> >
> > What this is about:
> > David Edelsohn wanted to have new library functions, one for each of these 6 single-precision functions:
> > sinf, cosf, sincosf, expf, logf, powf; and these 6 double-precision functions:
> > sin, cos, sincos, exp, log, and pow.
> > For the single-precision functions, the corresponding new functions would compute 4 results
> > simulatneously. For the double-precision functions, the new ones would compute 2 results
> > simultaneously.
> > x86_64 has already done something very similar so I thought I would adapt as much of their
> > documentation and implementation as I could for PPC64.
> > Let's start with that. Comments so far?
>
> That sounds like libmvec?
>
> I still don't know what this is.
>

Yes, it is libmvec.

Now look at what GCC does to the code in Examples 1 and 2 at this link:
https://sourceware.org/glibc/wiki/libmvec

x86_64 added functionality to GCC so such code uses the new functions without the user
having to re-write the loops and explicitly call the new functions.

We are aiming to provide that same capability for PPC64 in GCC.

Bert.


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