[cfe-dev] moving the clang-omp merge along
Jack Howarth
howarth.mailing.lists at gmail.com
Thu May 29 08:01:15 PDT 2014
Alp,
My take on this is that we have a chicken and the egg situation here.
As long as the
clang-omp changes haven't been merged into clang trunk, we will be unable
to switch
the default of -fopenmp from -liomp5. So once the clang-omp merge is well
underway,
interest in integrating the openmp component into the existing build
machinery will
rapidly pick up.
Jack
On Thu, May 29, 2014 at 10:39 AM, Alp Toker <alp at nuanti.com> wrote:
> Thanks for the summary Andrey.
>
> The underlying problem For the OpenMP *runtime* is really lack of
> visibility and sidelining on the openmp-dev list.
>
> It's absolutely critical to close down the low-volume openmp-dev list and
> fold the subscribers into one of the more active mailing lists, either
> llvm-dev or cfe-dev.
>
> Until that's done the patches won't get review from the mainstream LLVM
> developer community, build system experts won't join in etc.
>
> Alp.
>
>
>
>
> On 29/05/2014 16:46, Andrey Bokhanko wrote:
>
>> All,
>>
>> To clarify, what I meant is getting OMP runtime library (not clang-omp
>> branch!) as a part of 3.5 release. I specifically referred to this thread:
>> http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-May/thread.html#73025started by Jack. I thought he means libiomp when saying "openmp support" --
>> apparently, I was mistaken. Hence the confusion.
>>
>> After so many talks with Chandler, I know very well that upstreaming full
>> OpenMP support is a long way to go. :-)
>>
>> Also, the whole desire to put the library into 3.5 release is a responce
>> to the criticism expressed by Chandler in this message:
>> http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-
>> Mon-20140217/099477.html.
>>
>> While we are on the topic, let me update on some other things happening
>> in responce to other issues highlighted by Chandler:
>>
>> - This library is not being developed as an active part of the LLVM
>> community, even if it is checked into SVN as part of the LLVM project and
>> under its license. See r197914 where there is a code drop of many months
>> worth of development with *no* change log, attribution, information, or
>> other participation in any part of the community.
>>
>> This is changing, and many developers joining the whole OpenMP in clang
>> support effort. I can say that Michael Wong and many of his colleagues from
>> IBM are involved; Eric Stotzer and his colleagues from TI are involved;
>> Barbara Chapman and her group from UofHouston is involved; Guansong Zhang
>> from AMD is involved. Obviously, Hal Finkel, Chris Bergstrom, Steve Noonan
>> and many others continue to be actively involved as well.
>>
>> Take a look at the recent activity in openmp-dev mailing list. More to
>> come.
>>
>>
>> - There has been essentially *zero* discussion with the rest of the clang
>> or llvm community about this library. There are separate mailing lists
>> which have nearly no traffic since the code drop.
>>
>> Take a look at this month's messages: http://lists.cs.uiuc.edu/
>> pipermail/openmp-dev/2014-May/thread.html. In general, as more people
>> get interested, more traffic became generated. It's a chicken and egg
>> problem...
>>
>> - There has been no effort to make this library even work properly with
>> Clang as a host compiler. See the copious notes that only Clang 3.3 is
>> supported, and that not full featured.
>>
>> It is buildable with clang now. Moreover, regular buildbots, with both
>> gcc and clang, are running:
>>
>> http://lab.llvm.org:8011/builders/libiomp5-gcc-x86_64-linux-debian
>> http://lab.llvm.org:8011/builders/libiomp5-clang-x86_64-linux-debian
>>
>> - The build system is totally disjoint from LLVM's, in fact it is an
>> entirely custom Perl build system that is unlike anything in use by the
>> LLVM project.
>>
>> We started to work on improving build system. Stay tuned.
>>
>> - There are *zero tests* in the open source repository!!!! This is even
>> called out in the original submission and on the primary website. We
>> simply
>> *cannot* ship and link against a runtime library which has no tests!
>>
>> University of Houston contributed OpenUH test suite:
>> http://lists.cs.uiuc.edu/pipermail/openmp-commits/2014-May/000019.html.
>> Sunita Chandrasekaran from the University works on integrating this suite
>> into LLVM test system.
>>
>> BTW, any advice with how to approach this would be *much* appreciated!
>>
>> - No part of this library has gone through an LLVM release process either,
>> not even as a "new" or "beta" project.
>>
>> Aha! So, you support inclusion of openmp (library, not compiler) in 3.5
>> as well? :-)
>>
>> Andrey
>>
>>
>>
>> On Thu, May 29, 2014 at 2:19 AM, Jack Howarth <
>> howarth.mailing.lists at gmail.com <mailto:howarth.mailing.lists at gmail.com>>
>> wrote:
>>
>> Andrey Bokhanko expressed interest in getting the clang-omp
>> merge done in time for the 3.5 release but wants guidance on the
>> process. I suggested starting with the creation a new clang-omp
>> branch upstream rebased on clang trunk for generation of merge
>> patch. Unfortunately merging the current changes from the
>> clang-omp (based on clang 3.4) to a clang-omp (based on clang
>> trunk) looks very difficult as selective patches have been
>> committed into clang trunk from clang-omp and don't appear to have
>> been kept synchronized with the current changes from upstream.
>> Does anyone know if these new files from previous commits out of
>> clang-omp contain any local changes which haven't been back ported
>> to clang-omp? It would seem that postponing this merge will just
>> make the process harder as time goes on if selective merges from
>> clang-omp into clang trunk continue in the interim. Hopefully
>> the folks who did the original selective commits would help
>> detangle this mess.
>> Jack
>>
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>
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