[flang-dev] Flang Biweekly Sync - Notes from the October 30th, 2019 call

Gary Klimowicz via flang-dev flang-dev at lists.llvm.org
Tue Nov 5 07:18:55 PST 2019


Flang team,

Here are the notes from the October 30th, 2019 Flang biweekly call.

Please be sure to let us know if you have any questions and agenda topics for the next call.

The next Flang biweekly call will be Wednesday, November 13th, 2019 at 8:30 AM Pacific Time.

The Flang Technical Community call was Monday, November 4th, 8:30 AM Pacific Time.

Thank you.

Gary Klimowicz


Agenda

  *   LLVM Developer Meeting news
  *   Flang Community Technical Call – Recap and next topic
  *   F18 development update
  *   Flang development update


Highlights


  *   The new WebEx call meeting link is https://nvmeet.webex.com/nvmeet/j.php?MTID=mb4edb8c799f69ec2dc0554acc969a162.


  *   Supercomputing 2019
     *   The LLVM in HPC BoF session at SC 2019<https://sc19.supercomputing.org/program/birds-of-a-feather/> is scheduled for Wednesday, November 20, 5:15-6:45 PM. Here’s the BoF link: https://sc19.supercomputing.org/session/?sess=sess331.


  *   LLVM Developer Meeting 2019
     *   The LLVM Dev Meeting was October 22-23 at the San Jose Convention Center; details can be found here<https://llvm.org/devmtg/2019-10/>.
     *   The flang roundtable was Tuesday, October 22, from 2 pm until 3:10 pm. Steve Scalpone says there were two-tables-plus attendees.
     *   Eric Schweitz (NVIDIA) presented An MLIR Dialect for High-Level Optimization of Fortran<https://llvm.org/devmtg/2019-10/talk-abstracts.html#tech19>. It was well attended.
     *   There was much discussion of putting the new Flang into the LLVM monorepo, including all the current history. This will be done before MLIR is uploaded to LLVM. This requires some changes to MLIR to support installed files (like headers).


  *   Flang Community Technical Biweekly Call
     *   Hal Finkel is hosting this call on Bluejeans<https://bluejeans.com/625064848>, Mondays 8:30 Pacific Time, on the weeks alternating with this call. The notes for all these calls can be found in Google Docs here<https://docs.google.com/document/d/1Z2U5UAtJ-Dag5wlMaLaW1KRmNgENNAYynJqLW2j2AZQ/>.
     *   On the October 21st, 8:30 AM PDT, the agenda topic was experience with the new flang compiler and Rose with Craig Rasmussen.
     *   For the November 4th call, we did a brief recap of the LLVM Developer Meeting. Most discussion was about the upstreaming of Flang into LLVM. Talks and Flash Talks should be uploaded to YouTube, if they haven’t been already.
     *   We have no topic scheduled for the next call, November 18th. Please let Hal know topics you would like brought up.


  *   New Flang update
     *   Project created for tracking work on Flang driver: https://github.com/orgs/flang-compiler/projects/2.
     *   OpenMP name resolution semantics.
     *   Finishing generic resolution; this is necessary for expanding the testing available.
     *   Continued work on design of FIR.
     *   Began work on complex expression lowering to FIR.
     *   Continued work on procedure call semantics.
     *   MOVE_ALLOC semantics.
     *   The driver “flang” turns on semantic processing by default. This will make it easier for people to check existing codes against f18 and expanding the test suite in f18.
     *   The Arm Ltd pull request for Clang https://reviews.llvm.org/D63607 is being reviewed to be merged into Clang. It may be merged by the time you read this.


  *   Original Flang Dev news and updates
     *   More bug fixes sent to Flang.
     *   Support for the Fortran 2008 BLOCK construct is now in Flang.
     *   Initial assumed rank support, including the SIZE intrinsic, is now in Flang.
     *   Arm is helping with LLVM 9 changes to Flang (differences between LLVM 8 and 9).
     *   License update to Apache 2.0 with LLVM exceptions is coming very soon. This will touch nearly every file in flang.
     *   We will be decoupling PGI and Flang development to shorten turnaround on pull requests, add committers.


Where we can use your help

  *   Subscribe to the LLVM Flang email list: https://lists.llvm.org/cgi-bin/mailman/listinfo/flang-dev.
  *   Topics for the next biweekly community call and technical community call.
  *   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 1,654 total commits (1,623 in the previous update).
·         There are 485 people who have “starred” the flang repo and 69 forks.
·         190 people are following f18 in 28 forks. There have been 2,712 commits.


  1.  Flang Community Technical Call

  *   This 30-minute biweekly call is hosted by Hal Finkel at https://bluejeans.com/625064848 on the alternate Mondays on the weeks we do not have this call, at 8:30 AM Pacific time.
  *   Agenda topics and notes from the calls can be found in this <https://docs.google.com/document/d/1Z2U5UAtJ-Dag5wlMaLaW1KRmNgENNAYynJqLW2j2AZQ/edit#heading=h.oiag5i748hyl> Google doc. It also contains instructions for joining the meeting.
  *   The last call was October 21st. Craig Rasmussen discussed early experiences with f18 and the Fortran front-end for Rose.
  *   The last call was November 4th, a recap of the LLVM Developer Meeting. Most of the discussion was on upstreaming Flang into LLVM, preserving history, and treating MLIR as an external dependency for the time being.
  *   Future Topics and tentative dates:
     *   LLVM transition (mailing lists, git/monorepo, etc.)
     *   We’re looking for additional topics for the next calls.
  *   Meeting details:
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



  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 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. We are now using these lists:
     *   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.
  *   Biweekly call: The meeting link for this biweekly call is https://nvmeet.webex.com/nvmeet/j.php?MTID=mb4edb8c799f69ec2dc0554acc969a162.



  *   Supercomputing 2019
     *   The LLVM in HPC BoF session at SC 2019<https://sc19.supercomputing.org/program/birds-of-a-feather/> is scheduled for Wednesday, November 20, 5:15-6:45 PM. Here’s the BoF link: https://sc19.supercomputing.org/session/?sess=sess331.
     *   Please let us know any other talks or meetings you would like us to publicize here.


  *   LLVM Developer Meeting 2019

     *   The LLVM Dev Meeting was October 22-23 at the San Jose Convention Center.
     *   Eric Schweitz’s talk, An MLIR Dialect for High-Level Optimization of Fortran<https://llvm.org/devmtg/2019-10/talk-abstracts.html#tech19>, was presented.
     *   There was much discussion of putting the new Flang into the LLVM monorepo, including all the current history.



  1.  What we’re up to


  *   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:

     *   Project created for tracking work on Flang driver: https://github.com/orgs/flang-compiler/projects/2.
     *   OpenMP name resolution semantics.
     *   Finishing generic resolution; this is necessary for expanding the testing available.
     *   Continued work on design of FIR.
     *   Began work on complex expression lowering to FIR.
     *   Continued work on procedure call semantics.
     *   MOVE_ALLOC semantics.
     *   The driver “flang” turns on semantic processing by default. This will make it easier for people to check existing codes against f18 and expanding the test suite in f18.
     *   We continue to follow the MLIR project for the flang intermediate representation. There are a lot of changes from MLIR that we have to merge.
     *   Arm Ltd generated a pull request for Clang as a first step for the new flang driver. The pull request for adding --fortran-mode can be found here: https://reviews.llvm.org/D63607. This may be merged into Clang by the time you read this.


  *   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. Archives are also available.
     *   The flang-commits email list has also been set up. There is no content yet, as we haven’t migrated to the LLVM monorepo.
     *   The plan is to first upload some of the top-level documentation so the community can read the project goals and strategy before we do a big code dump. This should happen mid-June.
     *   No progress on adding flang to the LLVM repo. It was proposed the MLIR migrate to LLVM with all its previous history and commits (as clang did); this is not what we had proposed for Flang, but we will revisit this.


  *   Current Flang:

     *   Work continues on the Fortran 2008 BLOCK construct. This is now in Flang in GitHub.
     *   Began work on pointer initialization with non-NULL values.
     *   We will be making updates for the new Apache 2.0 license with LLVM exceptions. This needs to be reviewed by the NVIDIA intellectual property group. Changes here are likely to touch almost every file in Flang.
     *   We are in the process of incorporating changes to support LLVM 9.0. Our printf-based IR generation has some incompatibilities with LLVM 9.0. Arm has been helping with this work.
     *   We will be opening up Flang to more committers soon. We would like to get BLOCK and the license changes into Flang before adding committers.
     *   We will be decoupling PGI and Flang development to shorten turnaround on pull requests and other development activity.
     *   Recent fixes pushed to Flang
        *   More PGI bug fixes
        *   Changes to better support Arm processors
        *   Support for assumed rank arrays and SIZE intrinsic
        *   Support for Fortran 2008 BLOCK
        *   Support for Fortran 2008 pointer initialization with procedure pointers
        *   #812 Parameters listed in wrong order in Flang generated IR


     *   Upcoming changes to Flang (in review):
        *   Support for Fortran 2008 EXECUTE_COMMAND_LINE
        *   LLVM Apache 2.0 with LLVM exceptions licensing change
        *   Pull request #573 – libpgmath: make it clang friendly; addresses bug #557 (reviewing)
        *   Pull request #695 – Remove duplicate files


     *   Assigned for work:
        *   #226 Unlimited polymorphic type does not work with transfer intrinsic
        *   #298 norm2 intrinsic
        *   #402 Compiler error on regular code
        *   #404 Internal compiler error with polymorphic subroutine parameters and nested derived types
        *   #426 Failures in #include of OpenMPI's mpif.h
        *   #461 OpenMP TeaLeaf_ref: local pointer variable not captured into parallel region
        *   #477 Pull request for module variable import debug test
        *   #498 Error while compiling libpgmath
        *   #577 Procedure pointers to internal procedures
        *   #602 fd_sincos_scalar.cpp: "error: ‘__builtin_complex’ was not declared in this scope"
        *   #604 Flang errors out on a final subroutine with parameterized derived types
        *   #608 gdwarf-<version> flag is not honoured
        *   #610 No debug generated for namelists
        *   #662 Regression : Segfault in taskloop code
        *   #720 Segfault on sourced allocation of polymorphic variable
        *   #780 Linking CXX shared library libpgmath.dylib fails on macOS
        *   #787 ICE with array operations inside NORM2
        *   #807 possible memory corruption in function ompaccel_copy_arraydescriptors
        *   Pull request #573 libpgmath: make it clang friendly; addresses bug #557
        *   Pull request #695 runtime: remove duplicate files
        *   Pull request #710 Test case for capturing procedure pointers to OpenMP parallel regions
        *   Pull request #719 libpgmath: windows and osx support


  *   Outstanding pull requests:

  *   #521 Add OpenBSD as a recognized OS (pending test on new OpenBSD systems internally)
  *   #529 runtime: PoC: generate call to LLVM intrinsic instead of calling runtime functions when possible; handling NINT for a beginning (proposed expansion of this pull request)
  *   #530 AArch64: disable test cases invalid on aarch64 (working on)
  *   #532 runtime: remove duplicate files (need to validate on all compilers)
  *   #546 Loosen ties to x86 (working on)
  *   #572 libpgmath: respect LIBPGMATH_WITH_GENERIC setting; fixes #559 (reviewing)
  *   #592 add support for macOS (awaiting CLA)
  *   #622 Add explicit braces to avoid dangling else problem (failed NVIDIA testing)
  *   #642 AArch64: significantly improve formatted input performance by using optimized libc functions on ARM64
  *   #647 Introduce buffered I/O and replace getc with buffered read
  *   #655 Add missing signed integer to a pointer conversion in DATA statement
  *   #658 Fix in preprocessing for Flexi app
  *   #659 Changes to support transpose intrinsic during initialization
  *   #660 Enable support for simd directives
  *   #672 Support isnan() GNU extension (Arm reviewing)
  *   #689 Fix for segfault in multiple entries OpenMP functions
  *   #693 runtime: ARM64 is a 64-bit architecture
  *   #694 libpgmath sanity: do not call sleep() in Linux systems
  *   #695 runtime: remove duplicate files
  *   #701 Fix for ICE in taskloop
  *   #702 Fix for random_seed when seeds have zeroes in LSB
  *   #710 Test case for capturing procedure pointers to OpenMP parallel regions
  *   #717 Support building libpgmath with clang 6
  *   #725 Check for gregset_t before using it
  *   #726 Remove linux references where unneeded
  *   #737 TRAILZ function added to the fortran compiler (resubmitted)
  *   #738 Fix for issue #550
  *   #742 Implement UNROLL directive
  *   #751 Fix for len intrinsic returning int*8 in some cases
  *   #752 Fix for ICE in atomic instruction generation
  *   #756 Fix ICE interf:new_symbol_and_link, symbol not found
  *   #772 Fix unresolved sprintf, fprintf error
  *   #773 Support for isnan GNU extension: Generate isnanf() & isnan() libm calls
  *   #776 The BSDs name 64-bit x86 as amd64
  *   #778 Fixing NCAR test problems with error tolerance lower than E-12
  *   #787 ICE with array operations inside NORM2
  *   #807 possible memory corruption in function ompaccel_copy_arraydescriptors


  *   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 has been recently updated to reflect current Flang and F18 priorities and to provide better context for the project and its long-term goals.


  *   Creating pull requests: NVIDIA requires contributor agreements from developers wishing to make pull requests. The Individual CLA is here: https://flang-compiler.github.io/files/Flang-ICLA-v4.pdf. The Corporate CLA is here: https://flang-compiler.github.io/files/Flang-CCLA-v2.pdf. Send completed CLAs to flang-cla at nvidia.com<mailto:flang-cla at nvidia.com>. Assuming the pull request builds and passes “make check-flang”, NVIDIA will take on the internal testing of the pull request using the full test suite available internally and provide feedback to the contributor as appropriate. Once we have the quality of the pull request established, it will be incorporated into Flang.

  *   LLVM is switching to a new Apache license with LLVM exceptions that we need to incorporate into our CLAs after it is adopted by LLVM community. The LLVM license can be found at http://llvm.org/foundation/relicensing/LICENSE.txt. A web page describing the relicensing effort can be found at http://llvm.org/foundation/relicensing/.



  *   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.
        *   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.
     *   LLVM Debug metadata changes upstreamed to LLVM:
        *   https://reviews.llvm.org/D54043 [ELEMENTAL, PURE and RECURSIVE PROCEDURES]
        *   https://reviews.llvm.org/D54327 [COMMON blocks]


  *   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 is starting to work on Spack changes for the LLVM and Flang for the LLVM Git monorepo.


  *   Testing updates:

  *   NCAR Kernels tests take a long time to execute on some architectures, so we have moved them to longtests, based on Arm pull request.


  *   Application updates:
     *   No update.



  1.  Fortran 2008 features
Some Fortran 2008 features in development for pgfortran will flow into Flang soon.

  *   Allocation of polymorphic variables. This has been pushed to Flang.
  *   BLOCK construct. Fortran 2008 BLOCK support has been pushed to Flang.
  *   Pointer default initialization. Work continues. Support for pointer default initialization has been pushed to Flang.
  *   EXECUTE_COMMAND_LINE intrinsic. Support for Linux and Mac will be pushed to Flang soon.

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

  *   G0 edit descriptor
  *   NORM2 intrinsic
  *   ERROR STOP
  *   Pointers to internal procedures
  *   SUBMODULE
  *   Serial implementation of F2018 DO CONCURRENT
  *   BACK optional argument support for MINLOC/MAXLOC


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