[flang-dev] Flang Biweekly Sync - Notes from the May 13, 2020 call

Gary Klimowicz via flang-dev flang-dev at lists.llvm.org
Fri May 15 14:54:54 PDT 2020 

Flang team,

Here are the notes from the May 13th, 2020 Flang biweekly call.

The next Flang Technical Community will be Monday, May 18th, 8:30 AM Pacific Time.

The next Flang biweekly call will be Wednesday, May 27th, 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

  *   Follow-on meeting to discuss LLVM alias analysis
  *   LLVM Flang development update
  *   Original Flang development update

Highlights


  *   Alias analysis discussion
     *   In a previous technical call we discussed alias analysis for Fortran. Hal is scheduling a follow-on meeting to discuss potential improvements to LLVM's alias analysis to support handling restrict and restrict-like semantics. The Doodle poll to find a time to hold this call can be found at https://doodle.com/poll/evhwr2eyfvcf8ib3.


  *   LLVM Flang update
     *   Arm stood up a flang buildbot for Arm AArch64 at lab.llvm.org - see http://lab.llvm.org:8011/builders/flang-aarch64-ubuntu.
     *   Arm submitted work on OpenMP for parallel operation (lowering of simple subroutine without arguments).
     *   Handle size and offset computations and added constraint enforcement for COMMON and EQUIVALENCE.
     *   New implementation for TYPE constraints C741-C750.
     *   Continued work on lowering to FIR for alternate returns and end-of-I/O statement branching.
     *   Continued work on lowering: DNINT/FLOOR and STOP/ERROR STOP based on runtime updates.
     *   Continued work on lowering DATA statements and array initializers, including multidimensional arrays.
     *   AMD submitted semantics for SELECT RANK.
     *   See the detailed notes below for other Flang development updates.


  *   Original Flang Dev news and updates
     *   We’ve pushed a simple change to the stage branch of flang and are waiting for validation before merging into Flang.


  *   Flang Community Technical Biweekly Call
     *   The last call was Monday, May 4th: We discussed the status of the fir-dev branch and the plan to continue to migrate it to the master.
     *   The next technical call is scheduled for May 18th. We hope to discuss where people can contribute to Flang.
     *   Now what? Hal Finkel encourages people to 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.


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 1,676 total commits to github.com/flang-compiler/flang (no change since the previous update).
·         There are 528 people who have “starred” that flang repo and 76 forks.


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

  *   The last call was May 4th, 8:30 AM PT.
     *   We discussed the current state of the fir-dev branch of flang, and plans to continue to migrate changes into the master. It was recommended that NVIDIA continue to post patches to phabricator for review, both to get reviews on the changes themselves and to get recommendations on how the organize the changes into a reasonable number of commits.


  *   The next call will be Monday, May 18, 8:30 AM PT.
     *   Next call: Discussing places where other can contribute to LLVM Flang.


  *   Future Topics and tentative dates:
     *   Source-to-source translation (June 1, tentatively: Craig Rasmussen and Kate Rasmussen; they have been looking at flang for Fortran source-to-source translation. This is in conjunction with the work to do semantic analysis and support of coarrays)
     *   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.
  *   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.
     *   Virtual participation has always been part of their plan for the conference.
     *   The web site is at https://tcevents.chem.uzh.ch/event/12/.
     *   We plan to submit an abstract for a talk on the status of Flang.


  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:

     *   Arm stood up a flang buildbot for Arm AArch64 at lab.llvm.org - see http://lab.llvm.org:8011/builders/flang-aarch64-ubuntu.
     *   A build-bot for x86_64 at NERSC is almost ready.
     *   Arm submitted a review for master based on work that has not yet been merged from fir-dev branch (lowering of simple subroutine without arguments). This a large patch (about 3000 lines). We discussed the best way to merge these changes without forking too much from the fir-dev branch. This will probably be done in the fir-dev branch.
     *   Merged changes for MLIR and FIR; more to come. We continue to balance the size of the commits against the fairly large amount of code that needs to be merged. We continue to follow the plan outlined in flang-dev http://lists.llvm.org/pipermail/flang-dev/2020-January/000162.html.
     *   Handle size and offset computations and added constraint enforcement for COMMON and EQUIVALENCE.
     *   Added explicit conversions for implicit conversions from assignments.
     *   Continued work on semantic checking for TYPE (F2018 Clause 7). New implementation for constraints C741-C750.
     *   Continued work on lowering to FIR for alternate returns and end-of-I/O statement branching.
     *   Continued work on lowering: DNINT/FLOOR and STOP/ERROR STOP based on runtime updates.
     *   Continued work on semantic checks for DATA statements (in review).
     *   Continued work on lowering DATA statements and array initializers, including multidimensional arrays.
     *   Continued work on CHARACTER intrinsic runtime routines.
     *   Fixed decimal formatting of 80-bit x87 values.
     *   AMD added semantics for SELECT RANK.


  1.  What we’re up to with current Flang

     *   We pushed one pull requests to the stage branch. Waiting for approvals.
     *   We are using the Slack channel #classic-flang-pull-requests to coordinate among the contributors.
     *   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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