[llvm-dev] [Openmp-dev] [cfe-dev] RFC: Proposing an LLVM subproject for parallelism runtime and support libraries

Fri Apr 22 23:07:37 PDT 2016

No one is pushing forward *without* agreement. I'm trying to unstall the
thread. =D

On Fri, Apr 22, 2016 at 10:21 PM C Bergström <openmp-dev at lists.llvm.org>
wrote:

>
> Please ensure that you have more than just Carlo's feedback from the OMP
> side on this. If Intel isn't in agreement then you're leaving out the most
> important stakeholder. (I'd also ask that Hal weigh in since he has quite a
> bit of insight into the politics for this)
>
> Pushing forward quickly (steamroller) with something just because the
> thread "stalled" doesn't make any sense. Please work with those who have
> experience and expertise.
>
> I'll leave technical feedback for later after rereading the meat of
> proposal.
>
> On Sat, Apr 23, 2016 at 9:50 AM, Carlo Bertolli via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
>> Hi Chandler
>>
>> About your points:
>>
>> > 3) Initially, leave the OpenMP offloading stuff targeted at OpenMP.
>> Then, as it evolves, consider moving it to be another runtime in the broad
>> project if and when it makes sense.
>> > 4) As both OpenMP and SE evolve and are used some in the project,
>> evaluate whether there is a common core that makes sense to extract. If so,
>> do it and rebase them appropriately.
>>
>> I agree with you.
>>
>> I had some discussion within my group and there seems to be some
>> agreement that OpenMP offloading, if properly extended, could be used as a
>> plugin for SE. As time progresses and we learn more about SE we will be
>> able to re-evaluate this.
>>
>> Thanks
>>
>> -- Carlo
>>
>> [image: Inactive hide details for Chandler Carruth via cfe-dev
>> ---04/22/2016 06:02:24 PM---I feel like this thread got a bit stalled. I]Chandler
>> Carruth via cfe-dev ---04/22/2016 06:02:24 PM---I feel like this thread got
>> a bit stalled. I'd like to pick it up and try to suggest a path forward.
>>
>> From: Chandler Carruth via cfe-dev <cfe-dev at lists.llvm.org>
>> To: Mehdi Amini <mehdi.amini at apple.com>, Jason Henline <jhen at google.com>,
>> Hal Finkel <hfinkel at anl.gov>
>> Cc: llvm-dev <llvm-dev at lists.llvm.org>, cfe-dev <cfe-dev at lists.llvm.org>,
>> "openmp-dev at lists.llvm.org" <openmp-dev at lists.llvm.org>
>> Date: 04/22/2016 06:02 PM
>> Subject: Re: [cfe-dev] [Openmp-dev] [llvm-dev] RFC: Proposing an LLVM
>> subproject for parallelism runtime and support libraries
>> Sent by: "cfe-dev" <cfe-dev-bounces at lists.llvm.org>
>> ------------------------------
>>
>>
>>
>> I feel like this thread got a bit stalled. I'd like to pick it up and try
>> to suggest a path forward.
>>
>> I don't hear any real objections to the overall idea of having an LLVM
>> subproject for parallelism runtimes and support libraries. I think we
>> should get that created.
>>
>> I don't actually see any real objections to StreamExecutor being one of
>> the runtimes. There are some interesting questions however:
>> - Is there common code in the OpenMP runtime that could be unified with
>> this?
>> - Could OpenMP end up using SE or some common shared library between them
>> as a basis for offloading?
>> - Would instead it make more sense to have the OpenMP offload library be
>> a plugin for StreamExecutor?
>>
>> I don't know the answer to any of these really, but I also don't think
>> that they should prevent us from making progress here. And I think if
>> anything, they'll become easier to answer if we do.
>>
>> So my suggestion would be:
>> 1) Create the broader scoped LLVM subproject, including writing up its
>> charter, scope, plans, etc.
>>
>> 2) Add stream executor to it
>>
>> 3) Initially, leave the OpenMP offloading stuff targeted at OpenMP. Then,
>> as it evolves, consider moving it to be another runtime in the broad
>> project if and when it makes sense.
>>
>> 4) As both OpenMP and SE evolve and are used some in the project,
>> evaluate whether there is a common core that makes sense to extract. If so,
>> do it and rebase them appropriately.
>>
>>
>> Does this make sense? Are there objections to moving forward here?
>> _______________________________________________
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>> cfe-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>
>>
>>
>>
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>>
>>
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