[flang-dev] Flang Biweekly Sync - Notes from the January 22nd, 2020 call

Gary Klimowicz via flang-dev flang-dev at lists.llvm.org
Fri Jan 24 14:40:23 PST 2020

Flang team,

Here are the notes from the January 22nd, 2020 Flang biweekly call.

The next Flang Technical Community call is scheduled for Monday, January 27th, 8:30 AM Pacific Time. Discussion will probably center on the necessary work to upload flang to the LLVM monorepo.

The next Flang biweekly call will be Wednesday, February 5th, 2020 at 8:30 AM Pacific Time. Note that this is the week of the ECP Annual Meeting.

Logistics information for these calls is at the end of this email.

Thank you.

Gary Klimowicz


  *   ECP Annual Meeting Feb 3-7
  *   Continue discussing merging process and status
  *   F18 development update
  *   Flang development update


  *   ECP Annual Meeting February 3-7, 2020, Houston Texas
     *   The Compiler Will Help You! The LLVM Compiler Infrastructure in ECP, Thursday Feb 6, 2020, 1:30 PM - 3:00 PM
     *   A Flang poster (Alexis Perry-Holby and Flang team) has been created.
     *   Pat McCormick would like to arrange a get-together for people working on Flang at the annual meeting. He’s working on arranging a space or this. Let Pat know if you will be attending the ECP Annual meeting.

  *   Flang Community Technical Biweekly Call
     *   The next call is scheduled for Monday, January 27th. Discussion about the process for uploading Flang to the LLVM monorepo will likely continue.
     *   Craig Rasmussen mentioned that he would be interested in talking about experience with flang for a rewriting scheme that they are working on. (It sounds like this might be related to a source-to-source implementation for coarrays, which Craig and Kate Rasmussen are working on.)

  *   New Flang update
     *   We continue to work through expectations and issues regarding flang’s readiness to be pulled into the LLVM monorepo. Arm is taking the lead on ensuring that we have a set of work items defined for what must be done before the upload, and what can be addressed afterwards.
     *   Most of the requests are not complicated: file suffix changes (.cpp instead of .cc); braces around single statements; incorporating tests into lit (the LLVM Integrated Testing framework) from ctest; etc.
     *   Other requests include things like greater use of LLVM data structures and file handling.
     *   See the detailed notes below for other Flang development updates.

  *   Original Flang Dev news and updates
     *   We will be providing access for additional committers to the project. There was discussion today around this process. Arm has submitted a list of additional committers for current Flang. We discussed setting up more public buildbots for Power (IBM will be looking into that) and x86.
     *   Each team will continue to test their proposed changes internally using their internal test infrastructure.
     *   This should help with the queue of pull requests that are outstanding for Flang.
     *   NVIDIA will continue to push fixes for GitHub issues to flang.

Where we can use your help

  *   Topics for the biweekly calls and technical community calls.
  *   Let us know if you have presentations or meetings relevant to the Flang community. We will publicize these in these notes.

Details (Updates below are in bold)

  1.  Flang on GitHub
·         There have been 1,676 total commits (no change since the previous update).
·         There are 501 people who have “starred” the flang repo and 69 forks.
·         214 people are following f18 in 42 forks. There have been 2,939 commits.

  1.  Flang Community Technical Call

  *   The next call is scheduled for January 27th, 8:30 AM PT.
     *   LLVM transition (continuation of discussions about uploading flang to the GitHub monorepo)
     *   Craig and Kate Rasmussen 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. Craig and Kate will present an overview of this work, probably at the call in two weeks (February 10).
  *   Future Topics and tentative dates:
     *   Potential topics for future calls include build times for the compiler and status updates on MLIR.

  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 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. Add yourself via the invite <https://join.slack.com/t/flang-compiler/shared_invite/enQtMjExOTEyMzQ3MjIxLTZkMDNlODc2YjgxZDY1NTQ2YWJiZWVhOGU2YWY0NDNiOWY0ZjQzNjYyZTNlZjBlNjgxY2U1ZjFjMmY5NzIwMzA> link.
  *   IBM has begun to attend the Flang calls. Welcome!

  1.  What we’re up to with new LLVM Flang Fortran 2018 compiler

  *   On GitHub: The source code f18 is available on flang-compiler.github.com/f18<https://github.com/flang-compiler/f18/>. It’s recommended to start in the “documentation” directory.
  *   Status: We continue development on the new Fortran 2018 front-end. Recent work includes:

     *   We continue to follow the MLIR project updates for FIR.
     *   Continued work on FIR/MLIR and the lowering bridge. We are working to refine the commits into about a dozen changes to merge into f18.
     *   Pointer semantic checks (pointer targets and association; not coindexed; etc.).
     *   Improved equivalence handling.
     *   Began work on format scanning.
     *   Continued work on character lowering (substring assignment, tests).
     *   Continued work on lowering control flow operations to FIR.
     *   Resumed work on OpenMP name resolution.
     *   Turned on semantic analysis by default.

  *   LLVM Project:

     *   The flang-dev email list has been set up on llvm.org. You can subscribe here: https://lists.llvm.org/cgi-bin/mailman/listinfo/flang-dev.
     *   The flang-commits email list has also been set up. There is no content yet, as we haven’t migrated to the LLVM monorepo.
     *   No progress on adding flang to the LLVM repo. Flang will migrate to the LLVM monorepo with its previous history and commits (as clang did, as MLIR plans). Peter Waller (Arm Ltd) is taking on the task of linearizing the commit history and pushing the results to the LLVM repo. This is complicated by the desire to preserve as much commit history as possible while coping with commits from branches that may be problematic to rebase.
     *   There are a number of other requests that have been made by the LLVM community to prepare flang for upload (file naming conventions, lit testing). Exactly what work gates the upload is under discussion.
     *   We plan to use the LLVM flang project board in GitHub to track the tasks necessary for uploading flang to the monorepo.
     *   Pat McCormick has a set of Cmake changes to be applied.
     *   Arm has a set of changes that will enable lit testing and the migration of existing ctest tests to lit.
     *   We expect Flang to be uploaded to LLVM in January.

  1.  What we’re up to with current Flang

     *   We are in the process of incorporating changes to support LLVM 9.0.
     *   We will be opening up Flang to more committers soon. We would like to get the license changes into Flang before adding committers.
     *   We have decoupled PGI and Flang development to shorten turnaround on pull requests and other development activity.
     *   Recent fixes pushed to Flang
        *   None

     *   Upcoming changes to Flang (in review, pending migration to Flang):
        *   #787<https://github.com/flang-compiler/flang/issues/787> ICE with array operations inside NORM2
        *   #825<https://github.com/flang-compiler/flang/issues/825> Defect #2 in recent polymorphic assignment feature
        *   #826<https://github.com/flang-compiler/flang/issues/826> Defect #3 in recent polymorphic assignment feature (fixed with #825)
        *   #827<https://github.com/flang-compiler/flang/issues/827> Defect #4 in recent polymorphic assignment feature
        *   #829<https://github.com/flang-compiler/flang/issues/829> Defect #5 in recent polymorphic assignment feature (fixed with #827)
        *   #830<https://github.com/flang-compiler/flang/issues/830> Defect #6 in recent polymorphic assignment feature
        *   #832<https://github.com/flang-compiler/flang/issues/832> Defect #8 in recent polymorphic assignment feature (fixed with #826)
        *   #842<https://github.com/flang-compiler/flang/issues/842> Loop in OMP DO statement not executed with dynamic scheduling

     *   Assigned for work:
        *   #664<https://github.com/flang-compiler/flang/issues/664> bind & save for variable (triaging)
        *   #667<https://github.com/flang-compiler/flang/issues/667> bind & shared library behavior bug (investigating a fix)
        *   #822<https://github.com/flang-compiler/flang/issues/822> Recent Arm ABI changes leads to compilation error (investigating)

  *   Outstanding pull requests:

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

  *   Public plan: NVIDIA has published a brief plan for upcoming Flang work on github.io at https://github.com/flang-compiler/flang/wiki/Roadmap. This reflects current Flang and F18 priorities and to provide better context for the project and its long-term goals.

  *   Creating pull requests: Contributor license agreements are no longer be required for the current flang compiler. We are defining the process by which pull requests are validated and reviewed before merging into Flang.

  *   OpenMP 4.5 support:
o    No update

  *   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>.

  *   Debug Metadata:
     *   LLVM Debug metadata changes posted to LLVM Phabricator for review; responding to review comments. The last remaining pull request can be found at https://reviews.llvm.org/D54114 [CHARACTER intrinsic data type]. Review for this is not complete, and we would like to get additional comments or alternate proposals.

  *   Packaging and Binary Releases:

  *   Binary release: We post binary releases at least quarterly. March binary releases of Flang for x86-64 and OpenPOWER (LLVM 7.0) have been posted to http://github.com/flang-compiler/flang/releases.
  *   Spack: Spack packages for Flang have been reviewed by the Spack team and pulled into Spack for flang_20180921. We are still working through issues with defining the spack package for flang. Brian Homerding and Nichols Romero are working on Spack changes for the LLVM and Flang for the LLVM Git monorepo.

  *   Testing updates:

  *   No update.

  *   Application updates:
     *   No update.

  1.  Fortran 2008 features

  *   Pointer default initialization. Work continues. Support for procedure pointer default initialization in modules and submodules has been pushed to Flang. We plan to work on scalar pointer initialization next.

The following items are considered complete. Please report GitHub issues if you identify any problems.

  *   EXECUTE_COMMAND_LINE intrinsic.
  *   BLOCK construct.
  *   Allocation of polymorphic variables.
  *   G0 edit descriptor
  *   NORM2 intrinsic
  *   Pointers to internal procedures
  *   Serial implementation of F2018 DO CONCURRENT
  *   BACK optional argument support for MINLOC/MAXLOC

  1.  Call 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.

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))
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(see all numbers - https://www.bluejeans.com/premium-numbers)
Enter the meeting ID and passcode followed by #
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