Flang Biweekly Sync - Notes from the October 2nd, 2019 call

Flang team,

Here are the notes from the October 2nd, 2019 Flang biweekly call.

We had difficulty getting the call started; for some reason the WebEx was canceled or expired. Only about a half-dozen people attended, but it was still a good discussion. I apologize for the inconvenience and have sent out a new invitation. (I have canceled the old, unusable invitation.)

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, October 16th, 2019 at 8:30 AM Pacific Time.

The Flang Technical Community call was Monday, October 7th, 8:30 AM Pacific Time. The topic was Fortran debug metadata and DWARF generation.

The next Flang Technical Community call will be Monday, October 21st, 8:30 AM Pacific Time. The topic will be experience with the new flang compiler and Rose with Craig Rasmussen.

Thank you.

Gary Klimowicz


  • SC 2019 – BoF for LLVM has been scheduled
  • LLVM Developer Meeting news
  • MLIR for HPC Workshop news (at LCPC 2019)
  • Flang Community Technical Call – Recap and next topic: Fortran debug metadata
  • F18 development update
  • Flang development update


  • Difficulties getting the call started this morning

  • The WebEx call was somehow expired. We had a lot of difficulty starting the call.

  • A new meeting request has been generated, which you should have already received.

  • I canceled the old meeting request. If it doesn’t automatically disappear from your calendar, you can delete the old one manually.

  • The new meeting link should be https://nvmeet.webex.com/nvmeet/j.php?MTID=mb4edb8c799f69ec2dc0554acc969a162.

  • Supercomputing 2019

  • The LLVM in HPC BoF session at SC 2019 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 is October 22-23 at the San Jose Convention Center; details can be found here.

  • Eric Schweitz (NVIDIA) will present An MLIR Dialect for High-Level Optimization of Fortran.

  • Steve Scalpone will try to set up a roundtable meeting for Flang.

  • MLIR for HPC Workshop 2019

  • The MLIR for HPC workshop will be held October 21st in conjunction with the 32nd Workshop on Languages and Compilers for Parallel Computing October 22-24 at Georgia tech.

  • Flang Community Technical Biweekly Call

  • Hal Finkel is hosting this call on Bluejeans, 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.

  • On the September 23rd call, we discussed flangd, a tooling prototype, connecting an IDE to f18 via the Language Server Protocol (LSP).

  • The next call is scheduled for Monday, October 7th, 8:30 AM PDT. The agenda topic is Fortran debug metadata and DWARF.

  • F18 as an LLVM project

  • The LLVM-hosted flang-dev mailing list has been set up. Subscribe at https://lists.llvm.org/cgi-bin/mailman/listinfo/flang-dev.

  • F18 flang is still waiting to be added to the LLVM repo, but we are continuing to work with the LLVM admins; Hal is lending his support as well.

  • Johannes Doerfert recommended that the f18 team attend the biweekly OpenMP LLVM call as well. It looks like one needs to get in touch with Ravi Narayanaswamy to be invited to the call ravi.narayanaswamy@intel.com.

  • Zaak Beekman of Paratools introduced himself as developer for TAU, OpenCoarrays, and Mac homebrew packages.

  • F18 update

  • Implemented name resolution for different names for relational operators (e.g., operator(.ne.), operator(/=), operator(<>)).

  • Improved .mod file writing.

  • Completed implementing semantic checks for the restrictions on “specification expressions”.

  • Addressing issues and fixing bugs.

  • Working on procedure interfaces

  • We have two developers working on FIR. Eric Schweitz is now a committer on MLIR, and has two changes merged. (What he believes is the last one remains in review.)

  • OpenMP semantic checking continues, including contributions by David Truby.

  • Johannes asked why the f18 build was so slow. We think this has to do with the extensive use of constexprs. We hear rumors of a clang pull request that would improve this and look forward to its implementation.

  • 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.

  • 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.

  • Flang Dev news and updates

  • More bug fixes sent to Flang.

  • Some pull requests have been addressed.

  • Work continues on the BLOCK construct. BLOCK inside an OpenMP construct is likely not supported in flang.

  • Working on LLVM 9 changes to Flang (differences between LLVM 8 and 9).

  • License update to Apache 2.0 with LLVM exceptions is coming.

  • 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 are in bold)