Obsolete powerpc*-*-*spe*

Segher Boessenkool segher@kernel.crashing.org
Thu Mar 16 21:11:00 GMT 2017

On Thu, Mar 16, 2017 at 08:38:37PM +0000, Andrew Jenner wrote:
> >>Are you proposing to take on the task of actually splitting it yourself?
> >>If so, that would make me a lot happier about it.
> >
> >Yes, I can do the mechanics.  But I cannot do most of the testing.
> That's fine (and what I expected).
> >And
> >this does not include any of the huge simplifications that can be done
> >after the split: both ports will be very close to what we have now,
> >immediately after the split.
> I'd have thought that the simplifications would be the bulk of the 
> work...

The simplifications are not necessary to make things work.  They can
all be done piecemeal, and later (we should do the split during early
stage1 if possible).

I cannot promise you much of IBM's time (or my own abundant spare time),
but we will of course be available for advice and questions etc.

It is not like removing 20k or 30k lines is as much work as writing
them, of course ;-)

> The simplification of the classic PowerPC port would be the 
> removal of the SPE code. What would be removed from the SPE port - 
> anything other than Altivec and 64-bit?

Don't forget the other vector stuff, VSX.  It is not small or simple.

> >>All the e200 cores apart from e200z0 can execute 32-bit instructions as
> >>well as VLE, though we'll always generate VLE code when targetting them
> >>(otherwise they're fairly standard).
> >
> >Do any e200 support SPE, or classic FP?
> The e200z3 upwards have SPE units. None of them have classic FP. So it 
> would make most sense for the e200/VLE support to be part of the SPE 
> backend rather than the classic PowerPC backend.

Great to hear!  And all e300 are purely "classic"?


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