[llvm-dev] Scalable Vector Types in IR - Next Steps?

[Finkel, Hal J. via llvm-dev]

On 3/15/19 5:18 AM, Graham Hunter via llvm-dev wrote:
> Hi David,
>
>> We tried two round tables at the Nov. LLVMDev and no serious objections
>> were raised, but we knew we didn't have all the right people there.  I
>> am somewhat skeptical another roundtable without commitment to attend
>> from all able parties ahead of time will accomplish much.
> Agreed, but I'll try scheduling one anyway.
>
>> Speaking for myself (and not Cray), it is frustrating to have had a
>> bunch of discussion on the mailing list and in reviews where concerns
>> were raised and to see a lot of radio silence to responses to those
>> concerns, only to see a message about a potential change in direction
>> driven by off-list discussions where concerns and responses to concerns
>> are unknown and therefore not addressable.
> I didn't want private meetings either, but repeatedly requesting public
> feedback for the RFC or patches hadn't provided reasoning behind any
> concerns that people had.
>
> The agreement reached at the meeting was for the objectors to post their
> reasons for objecting and counter-proposal in public so discussion could
> take place, and Arm would investigate the details of the counter-proposal.


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).

  -Hal


>
> Unfortunately, that post never happened, so I found myself a bit stuck and
> had to post it for them -- not a situation I wanted.
>
> I have always wanted the discussion to take place in public.
>
>> I completely understand that ARM needs to make progress and I very much
>> want to see that progress.  I just don't want to see a Plan B leading to
>> a situation where VLA support doesn't ever make it into LLVM.  It is
>> somewhat embarrassing that gcc already has a release with VLA support
>> for SVE and LLVM is stuck in the starting blocks.
> Agreed.
>
> -Graham
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-- 
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory