[flang-dev] Flang Biweekly Sync - Notes from the June 24, 2020 call

Gary Klimowicz via flang-dev flang-dev at lists.llvm.org
Fri Jun 26 09:57:42 PDT 2020 

Flang team,

Here are the notes from the June 24, 2020 Flang biweekly call.

The next Flang Technical Community will be Monday, June 29, 8:30 AM Pacific time. We will be discussing the status of lowering and code generation for LLVM Flang.

The next Flang biweekly call will be Wednesday, July 8, 2020 at 8:30 AM Pacific time.

Information for joining these calls and the Slack channel is at the end of this email.

Let me know if you have any topics you would like covered in the next call.

Thank you.

Gary Klimowicz


Agenda

  *   ISC and LLVM Workshop on LLVM Compiler and Tools for HPC
  *   International Fortran Conference
  *   LLVM Technical Call topic
  *   LLVM Flang development update
  *   Classic Flang pull request process update

Highlights


  *   LLVM Workshop on Compilers and Tools for HPC at ISC 2020 Digital
     *   June 25th, Thursday this week.
     *   Talks by Kiran Chandramohan (Arm, OpenMP in Flang) and Will Lovett (ARM, Scalable vector extensions)
     *   Steve Scalpone (NVIDIA) talk on Compiling Three Generations of Fortran with LLVM (flang/f18)


  *   International Fortran Conference 2020 Digital
     *   Gary Klimowicz (Flang) Thursday July 2, 9:20 AM PT
     *   Ondřej Čertík (LFortran) Thursday July 2, 9:50 AM PT
     *   Many other talks that may be of interest; web site is https://tcevents.chem.uzh.ch/event/12/. Registration is free.


  *   Flang Community Technical Biweekly Call
     *   Next topic: Outstanding reviews. Update on lowering and code generation work.
     *   The last call was June 15. Discussed outstanding reviews including clang/flang/llvm driver refactoring proposal and pull request regarding llvm_unreachable.
     *   Please add both small and large technical topics to the Google Doc for the technical call. The link to the Google Doc can be found in the notes below.


  *   LLVM Flang update
     *   Hal Finkel is working to identify a regular time every 4 weeks to continue the discussions on LLVM alias analysis. The Doodle poll is at https://doodle.com/poll/9iqfaqttvvic5rfp.
     *   Arm buildbots are http://lab.llvm.org:8011/builders/flang-aarch64-ubuntu (GCC 9.3) and http://lab.llvm.org:8011/builders/flang-aarch64-ubuntu-clang (Clang 8).
     *   NERSC and Argonne National Lab are working to set up buildbots as well (in administrative limbo). NERSC buildbot is in progress (no update this week).
     *   Andzrej Warzynski and Carol Concatto continue to prototype their work on the flang driver (and clang/llvm refactor of driver code); should be an update in a couple weeks.
     *   Improved parser support for OpenMP (AMD).
     *   Change DIE("unreachable") cases to use llvm_unreachable (Arm).
     *   Implemented shape analysis for MATMUL, rewriting of AMIN0, ..., AMAX1 intrinsics.
     *   Completed work on compiling all DATA statement initializations.
     *   Continued work on run-time for CHARACTER operations, and dummy argument procedure passing.
     *   Continued work on MLIR and FIR in f18-llvm-project. Continued to push small commits to llvm-project for the fairly large amount of code that needs to be merged.
     *   Bug fixing for SAVE attribute, F format, alternate returns in modules, control flow issues.
     *   Nick Romero at Argonne is working on running Office of Science codes through the front-end. Mostly working around GCC extensions not supported by flang. Modern Fortran is getting through flang well.


  *   Original Flang Dev news and updates
     *   We've pushed a simple change to the stage branch of flang.
     *   We published the RFC to flang-dev on handling the outstanding pull requests for classic Flang. Arm, AMD and NVIDIA (others are welcome!) will be evaluating the pull requests for merge into the master branch. No significant feedback received on the RFC. Look in flang-dev for subject '[classic-flang]' if you're interested.


Details (Updates below are in bold)


  1.  Flang on GitHub
*         F18 has moved to https://github.com/llvm/llvm-project/tree/master/flang.
*         There have been 2422 commits for flang encompassing over 148,000 lines of code, documentation, CMakefiles and tests.
*         There have been 1,676 total commits to github.com/flang-compiler/flang (no change since the previous update).
*         There are 534 people who have "starred" that flang repo and 80 forks.



  1.  Flang Community Technical Call (Hosted by Hal Finkel)

  *   The last call was June 15. Discussion of outstanding pull requests for clang/flang/llvm front-end refactoring and llvm_unreachable.


  *   The next call will be Monday, June 29, 8:30 AM PT.
     *   Outstanding reviews.
     *   Recent progress on lowering and code generation.


  *   Future Topics and tentative dates:
     *   Build times for the compiler.
     *   Please feel free to add agenda topics to the Google Doc: https://docs.google.com/document/d/1Z2U5UAtJ-Dag5wlMaLaW1KRmNgENNAYynJqLW2j2AZQ/



  1.  Flang community

  *   Website: www.flang-compiler.org<http://www.flang-compiler.org> redirects to http://github.com/flang-compiler/flang.
  *   Wiki: https://github.com/flang-compiler/flang/wiki is the Flang wiki page where the most up-to-date build instructions and news can be found.


  *   Issues:
     *   Bug reports for LLVM flang should be reported in Bugzilla: https://bugs.llvm.org/. Use the "flang" tag for flang-related issues, please.
     *   Bug reports for current Flang can be reported to https://github.com/flang-compiler/flang/issues.


  *   LLVM mailing lists: There are now two mailing lists hosted by llvm.org:
     *   The flang-dev mailing list has been set up. Subscribe at https://lists.llvm.org/cgi-bin/mailman/listinfo/flang-dev. These biweekly notes are now sent to this email list.
     *   The flang-commits mailing list has been set up. Subscribe at https://lists.llvm.org/cgi-bin/mailman/listinfo/flang-commits.


  *   Slack: flang-compiler.slack.com is used for informal real-time communication in the Flang community. The invitation link can be found at the end of this email.


  *   LLVM Workshop on Compilers and Tools for HPC at ISC 2020 Digital
     *   June 25th, Thursday this week.
     *   Talks by Kiran Chandramohan (Arm, OpenMP in Flang) and Will Lovett (ARM, Scalable vector extensions)
     *   Steve Scalpone (NVIDIA) talk on Compiling Three Generations of Fortran with LLVM (flang/f18)


  *   International Fortran Conference
     *   FortranCon 2020 is the first International Conference targeting the development for and with the Fortran programming language and will take place on July 2 - 4 in Zurich, Switzerland. The web site is https://tcevents.chem.uzh.ch/event/12/. Registration is free.
     *   The schedule is now available and generally runs 4:00 am - 1:00 pm Pacific time.
     *   Gary Klimowicz (Flang) Thursday July 2, 9:20 AM PT.
     *   Ondřej Čertík (LFortran) Thursday July 2, 9:50 AM PT.



  1.  What we're up to with the llvm-project/flang Fortran 2018 compiler

  *   On GitHub: The source code LLVM Flang is available on https://github.com/llvm/llvm-project/tree/master/flang. It's recommended to start in the "documentation" directory.


  *   Public plan: The team maintains a plan for upcoming Flang work at https://github.com/orgs/flang-compiler/projects/. This reflects current LLVM Flang priorities and context for the project and its long-term goals.


  *   Status: We continue development. Recent work includes:

        *   We had a good call last month on alias analysis in LLVM. Notes from the last call are available at https://docs.google.com/document/d/1ybwEKDVtIbhIhK50qYtwKsL50K-NvB6LfuBsfepBZ9Y/. Hal Finkel is working to identify a regular time every 4 weeks to continue the discussions. He has a Doodle poll at https://doodle.com/poll/9iqfaqttvvic5rfp to try to find the right time for this next meeting.
        *   Arm buildbots are set up at http://lab.llvm.org:8011/builders/flang-aarch64-ubuntu (GCC 9.3) and http://lab.llvm.org:8011/builders/flang-aarch64-ubuntu-clang (Clang 8).
        *   NERSC, LANL and Argonne National Lab are working to set up buildbots as well. NERSC buildbot is running, but failing; Brian Friesen is working through the issues. Argonne is working with ECP and security resources to negotiate whether they can set up their buildbot. LANL is facing the same uphill battle.
        *   Andzrej Warzynski and Carol Concatto continue to work on the flang driver.

     *   Implemented shape analysis for MATMUL.
     *   Implemented rewriting of AMIN0, ..., AMAX1 intrinsics to properly handle conversions.
     *   Completed work on compiling all DATA statement initializations.
     *   Continued work on run-time for CHARACTER operations.
     *   Continued work on MLIR and FIR in f18-llvm-project. Continued to push small commits to llvm-project for the fairly large amount of code that needs to be merged.
     *   Continued work on dummy argument procedure passing.
     *   Bug fixing for SAVE attribute, F format, alternate returns in modules, control flow issues.
     *   Testing fixes for running individual tests.
     *   Improved parser support for OpenMP.
     *   Change DIE("unreachable") cases to use llvm_unreachable.
     *   Nick Romero at ANL is working on compiling Office of Science codes through the front-end. Mostly working around GCC extensions not supported by flang (DFLOAT, shift intrinsics, ...). He will report high-priority extensions to support to the flang developers.





  1.  What we're up to with current Flang

     *   We sent an RFC to flang-dev on the handling of pull requests for merge into Flang. This will involve multiple parties contributing to the testing effort for the pull requests. Only one response (off-list) received. The process was adjusted to make it easier to work on multiple pull requests simultaneously. Look in flang-dev email for the subject '[classic-flang]' if you're interested in commenting.
     *   We are using the Slack channel #classic-flang-pull-requests to coordinate what pull requests we are working on.
     *   We will use the pull requests themselves for discussion of the content of the pull requests (validation progress, need for tests, code comments, need to bring current, etc.).
     *   Recent fixes pushed to Flang stage
        *   #875<https://github.com/flang-compiler/flang/pull/875> Spelling fixes (a simple change)
     *   Recent fixes pushed to Flang master
        *   None

     *   Outstanding pull requests: https://github.com/flang-compiler/flang/pulls for the current list of pull requests.

     *   Outstanding issues: Please refer to the Issues section on GitHub for flang-compiler/flang<https://github.com/flang-compiler/flang/issues> and flang-compiler/flang-driver<https://github.com/flang-compiler/clang/issues>.


  *   OpenMP 4.5 support:
o    No update. OpenMP effort is now directed toward LLVM Flang.


  *   Debug Metadata:
     *   The outstanding review at https://reviews.llvm.org/D54114 [CHARACTER intrinsic data type] is stale and has been canceled. It will be replaced when there is an appropriate update for LLVM Flang.


  *   Packaging and Binary Releases:

  *   Spack: Spack packages for Flang have been updated. There is also a spack package for f18, based on the flang-compiler/f18 repository.


  *   Current Flang Fortran 2008 features
Current status of Fortran 2008 features can be found at https://github.com/flang-compiler/flang/wiki/Fortran-2008.



  1.  Logistics
Flang Community Biweekly Call

     *   General updates on the Flang project, both LLVM Flang and current Flang.
     *   Biweekly WebEx hosted by NVIDIA (which these notes cover).
     *   The meeting link for this biweekly call is https://nvmeet.webex.com/nvmeet/j.php?MTID=mb4edb8c799f69ec2dc0554acc969a162.

Note: If you are having difficulty connecting your audio, try using the "Call Me" option on WebEx to connect audio to your telephone.


Flang Community Technical Biweekly Call

     *   Technical topics call.
     *   Hal Finkel hosts this call on Bluejeans<https://bluejeans.com/625064848>, Mondays 8:30 Pacific Time, on the weeks alternating with regular Flang biweekly call. The notes for all these calls can be found in Google Docs here<https://docs.google.com/document/d/1Z2U5UAtJ-Dag5wlMaLaW1KRmNgENNAYynJqLW2j2AZQ/>.
Meeting URL: https://bluejeans.com/625064848?src=join_info
Meeting ID: 625 064 848
Want to dial in from a phone? Dial one of the following numbers:
+1.408.317.9254 (US (San Jose))
+1.866.226.4650 (US Toll Free)
(see all numbers - https://www.bluejeans.com/premium-numbers)
Enter the meeting ID and passcode followed by #
Connecting from a room system?
Dial: bjn.vc or 199.48.152.152 and enter your meeting ID & passcode

Flang Slack Channel

     *   There is a Slack channel dedicated to Flang.
     *   Add yourself via the invitation link https://join.slack.com/t/flang-compiler/shared_invite/zt-2pcn51lh-VrRQL_YUOkxA_1CEfMGQhw

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