llvm dev - Mar 2019 - Scalable Vector Types in IR - Next Steps?

On Fri, 15 Mar 2019 at 15:30, Finkel, Hal J. via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> I've talked with a number of people about this as well, and I think
that
> I understand the objections. I'm happy that ARM followed through with
> the alternate set of patches. Regardless, however, unless those who had
> wished to object still wish to object, and then actually do so, we now
> clearly have a good collection of contributors actively desiring to do
> code review, and we should move forward (i.e., start committing patches
> once they're judged ready).
Let's start by closing the three flying revisions, so that people that
weren't involved in the discussion don't waste time looking at them.

Graham, can you also add a comment to reflect the change in
implementation while closing?

Second, it would be very good if someone, anyone, would write an RFC
on the new proposal. Graham started it on this thread and on the two
reviews, but this thread is now dead. We should have a new one, with
subject "RFC etc" and the contents of the current understanding, so
that it can serve as context for the two reviews.

Thanks!
--renato

Renato Golin <rengolin at gmail.com> writes:
> On Fri, 15 Mar 2019 at 15:30, Finkel, Hal J. via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> I've talked with a number of people about this as well, and I think
that
>> I understand the objections. I'm happy that ARM followed through
with
>> the alternate set of patches. Regardless, however, unless those who had
>> wished to object still wish to object, and then actually do so, we now
>> clearly have a good collection of contributors actively desiring to do
>> code review, and we should move forward (i.e., start committing patches
>> once they're judged ready).
>
> Let's start by closing the three flying revisions, so that people that
> weren't involved in the discussion don't waste time looking at
them.
See the reply I just posted to Hal.  I am not sure we've made a decision
to abandon the current patches.  We may in fact decide that, but I
haven't seen consensus for doing so yet.  In fact I've seen the opposite
-- that people want to move forward with the scalable types.

                       -David

On Fri, 15 Mar 2019 at 15:58, David Greene <dag at cray.com>
wrote:
> See the reply I just posted to Hal.  I am not sure we've made a
decision
> to abandon the current patches.  We may in fact decide that, but I
> haven't seen consensus for doing so yet.  In fact I've seen the
opposite
> -- that people want to move forward with the scalable types.
I did see that reply.

While, like Hal, I do understand some concerns on introducing a
radical new concept to IR (the reason why I started this thread), I'm
unaware (mainly by not being on that meeting) of the individual issues
and how controversial they were with those involved.

Furthermore, the current state is uncertain and people need to be
convinced more of what will work by means of hacking up more
intrinsics and more kludge into the current IR.

This means that, even if we are to implement it natively in IR, it
won't come *before* we implement it with intrinsics, which will
hopefully convince people that this makes sense, and by which time,
the code will look completely different and we'll need a completely
new patch.

Ie. the current series is already dead, no matter what we do.

cheers,
--renato

On 3/15/19 10:58 AM, David Greene wrote:
> Renato Golin <rengolin at gmail.com> writes:
>
>> On Fri, 15 Mar 2019 at 15:30, Finkel, Hal J. via llvm-dev
>> <llvm-dev at lists.llvm.org> wrote:
>>> I've talked with a number of people about this as well, and I
think that
>>> I understand the objections. I'm happy that ARM followed
through with
>>> the alternate set of patches. Regardless, however, unless those who
had
>>> wished to object still wish to object, and then actually do so, we
now
>>> clearly have a good collection of contributors actively desiring to
do
>>> code review, and we should move forward (i.e., start committing
patches
>>> once they're judged ready).
>> Let's start by closing the three flying revisions, so that people
that
>> weren't involved in the discussion don't waste time looking at
them.
> See the reply I just posted to Hal.  I am not sure we've made a
decision
> to abandon the current patches.  We may in fact decide that, but I
> haven't seen consensus for doing so yet.  In fact I've seen the
opposite
> -- that people want to move forward with the scalable types.

I agree with David. We should move forward with native support for
scalable types.

 -Hal
>
>                        -David
-- 
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory