TheRock/compiler/amd-llvm/flang/docs/MeetingNotes/2026/2026-01-21.md

Special Combined Call 2026-01-21

Agenda

• Design docs and/or RFCs
  • Flang failure with thin lto on LLVM 22-RC1
    • https://github.com/llvm/llvm-project/issues/176404
  • [RFC] What to do regarding the Flang Call Notes document
    • Tarun- Not keen on keeping it in the Flang repo, mostly due to folks needing commit access to add or update anything. He is not that concerned about relying on Discourse, since LLVM has officially adopted it if they do decide to make a change it is likely that the notes would be migrated
    • What about a wiki? Does LLVM have a policy on this, or gist?
    • Idea: Working Google Doc, post agenda in Slack day before the meeting and request for comments, final notes copied into MD doc in the repo
      • Example of another document/repo structure: https://github.com/triton-lang/triton/tree/main/docs/meetups
  • [RFC] Support classic flang driver options in flang
    • Do we want to support the spelling of certain options that are available in classic flang?
    • Tarun: Not inclined to do this as nearly all of the requested options have equivalent flang/gfortran version
    • Poll results: ambiguous, leading choice was to use a case-by-case basis
    • Idea: add them in with a deprecation warning to ease users transitions to LLVM Flang
    • Tarun will post update to the RFC
  • Cross-compilation of real(kind=16)
    • Issue involves library availability which can cause link-time failures, for example
    • There is a proposed solution in the Discourse post
  • [RFC] Support -fstrict-aliasing and -fno-strict-aliasing
    • Related issue: https://github.com/llvm/llvm-project/issues/171912
    • Gfortran supports -fno-strict-aliasing, Michael Klemm contacted their communtiy to inquire about it, turns out there is nothing special done for Fortran when that flag is passed
    • Would appreciate feedback from someone with more experience with end-users
    • Discussion leaned towards not accepting these options
  • `-ffp-contract=fast` Violates the Fortran Standard
    • Reply from the standards committee: https://mailman.j3-fortran.org/pipermail/j3/2026-January/015531.html
    • What happens when FMA does have a different precision than a multiply and add?
    • How do you control FMAs, since this is something that users are going to want to employ?
    • Cray and nvfortran have a specific control for FMAs, independent of opt level and other things
  • Changes to builtin modules
    • PR was reverted due to buildbot failure involving Windows
    • Undergoing another review process, will not try landing again until after the first of the year
  • [RFC] Use pre-compiled headers to speed up LLVM build by ~1.5-2x
    • Related to what has already been done in Flang, attempt to use this approach more generally
    • Draft PR: https://github.com/llvm/llvm-project/pull/173868
  • Improvement of Fujitsu test suite
  • [RFC] Add a New Byte Type to LLVM IR
    • Among other things, “Fixes known correctness bugs in memcpy lowering and load merging/widening”. Semantics are different from integer types and may allow other memory optimizations. This is a step towards eventual removal of Undef from LLVM-IR.
    • Related group working towards a formal specification of LLVM-IR
• PRs of Note
  • [Flang][FIR] Introduce FIRToCoreMLIR pass. #168703
• Issues of Note
  • Building Flang with offload support
• FYI
  • 2026 LLVM Community Area Team Elections - Call for Nominations
  • Added LoopInvariantCodeMotion pass for [HL]FIR. (PR #173438)
  • Call for Mentors - 2026 EuroLLVM Developers’ Meeting
    • https://discourse.llvm.org/t/call-for-mentors-2026-eurollvm-developers-meeting/89484/
    • Google Form here: EuroLLVM Mentorship Program Application
• Other topics as time allows
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