Flang Biweekly Sync - Notes from the July 08, 2020 call

Flang team,

Here are the notes from the July 8, 2020 Flang Community biweekly call.

The next Flang Technical Community will be Monday, July 13, 8:30 AM Pacific time.

The next Flang biweekly call will be Wednesday, July 22, 2020 at 8:30 AM Pacific time.

The next Classic Flang Technical biweekly call will be Wednesday, July 15, 2020 at 8:30 AM Pacific time. (This is a new open call for the original Flang.)

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


  • ISC and LLVM Workshop on LLVM Compiler and Tools for HPC (recap)
  • International Fortran Conference (recap)
  • Classic Flang technical biweekly call
  • LLVM Technical Call
  • LLVM Flang development update
  • Classic Flang update


  • LLVM Workshop on Compilers and Tools for HPC at ISC 2020 Digital

  • June 25-26

  • Talks by Kiran Chandramohan (Arm, OpenMP in MLIR and Flang) and Will Lovett (ARM Scalable Vector Extension in LLVM)

  • Steve Scalpone (NVIDIA) talk on Compiling Three Generations of Fortran with LLVM (slides to come)

  • International Fortran Conference 2020 Digital

  • Steve Lionel keynote (mostly Fortran 2018)

  • Lots of object-oriented Fortran (Arjen Markus’s talk and the Saturday workshop he led with Tiziano Müller and Vladimir Rybkin was very good)

  • Gary talked about Flang. Overall, Flang was well-received

  • Many other talks that were of interest; web site is https://tcevents.chem.uzh.ch/event/12/. Presentations are recorded.

  • Classic Flang biweekly call

  • There Classic Flang biweekly call is now open to anyone (especially vendors) who are interested in using and improving Classic Flang.

  • The call had been mostly for Classic Flang process and technical issues, hosted by Arm Ltd.

  • It occurs at the same time as this call, the weeks this call is not held (Wednesdays, 8:30 AM Pacific time).

  • Details for joining this call have been added to these call notes.

  • Flang Community Technical Biweekly Call

  • Next topic: Outstanding reviews. David Truby posted an RFC for LLVM 11; we will probably recap the outcome of this RFC.

  • The last call was June 29. Discussed current status of lowering and upstreaming from fir-dev to llvm-project (56% (by volume) complete at the time).

  • 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 updates

  • Hal Finkel is working to identify a regular time every 4 weeks to continue the discussions on LLVM alias analysis. Next meeting information is in the details below.

  • Andzrej Warzynski and Carol Concatto continue to work on the flang driver.

  • Merged work on external I/O runtime.

  • Continued work on ENTRY; subroutines pretty much done, but FUNCTION entries are tricky due to aliasing requirements on the result values.

  • Implemented statement function lowering. Started work on internal function lowering.

  • Completed work on passing intrinsics as function pointer actual arguments.

  • Continued to merge work from the fir-dev fork of Flang into Flang proper, including lowering of I/O statements. About 60% of fir-dev is merged.

  • Bug fixing from issues exposed by test suites, particularly FCVS.

  • Began implementation of semantics for coarrays (specifying image selectors, NUM_IMAGES intrinsic).

  • Improvements for parsing of OpenMP constructs.

  • Original Flang Dev news and updates

  • Kiran Chandramohan pushed PR#875 into Flang. This marks the first change pushed under the new Flang Community Pull Request process.

  • 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)