Re: Obsolete powerpc*-*-*spe*

[Segher Boessenkool <segher@kernel.crashing.org>]

Hi all,

On Wed, Mar 15, 2017 at 11:01:31AM +0100, Olivier Hainque wrote:
> > On Mar 13, 2017, at 19:01 , Andrew Jenner <andrew@codesourcery.com> wrote:
> > I volunteer to be the point of contact for the SPE port.
> > 
> > Over here at CodeSourcery/Mentor Embedded, we have a strong interest in SPE *not* being deprecated (we actively ship toolchain products with SPE multilibs, and have customers for which these are important). We are therefore volunteering resources (specifically, me) to maintain SPE upstream as well.
> > 
> > I am in the process of developing some patches to add VLE support upstream (and expect to be maintainer of those once they are committed) so it would be a good fit for me to be the SPE maintainer as well.
> > 
> > We have been regularly running tests on the SPE multilibs (on our internal branches) and they are in better shape than the test results Segher found from 2015. We may have some (not yet upstreamed) patches that improve the test results - I will be tracking these down and upstreaming them ASAP. I will be expanding our regular build and test runs to cover trunk as well, and will send test results to gcc-testsuite and report regressions.
> > 
> > If there is no objection, I will submit patches tomorrow to un-obsolete SPE and add myself to the appropriate section of the MAINTAINERS file. The other changes will come once stage 1 opens.
> 
> Thanks for volunteering!
> 
> As mentioned upthread, we (AdaCore) also have a significant user base,
> so a strong interest in the port remaining alive and we'll be happy to
> keep submitting patches we might have.
> 
> The perspective of seeing VLE support come in is great news :)

It is good to hear there are some parties who promise to do some actual
work for this :-)

I do not think VLE can get in, not in its current shape at least.  VLE
is very unlike PowerPC in many ways so it comes at a very big cost to
the port (maintenance and otherwise -- maintenance is what I care about
most).

Since SPE and VLE only share the part of the rs6000 port that doesn't
change at all (except for a bug fix once or twice a year), and everything
else needs special cases all over the place, it seems to me it would be
best for everyone if we split the rs6000 port in two, one for SPE and VLE
and one for the rest.  Both ports could then be very significantly
simplified.

I am assuming SPE and VLE do not support AltiVec or 64-bit PowerPC,
please correct me if that is incorrect.  Also, is "normal" floating
point supported at all?

Do you (AdaCore and Mentor) think splitting the port is a good idea?


Segher