[llvm-dev] Flang landing in the monorepo - next Monday!

Finkel, Hal J. via llvm-dev llvm-dev at lists.llvm.org
Wed Jan 8 18:53:48 PST 2020

FYI to everyone: If you have things that you would like to see done 
before a merge of Flang, please reply with as many details as you have 
time to provide (and if you have things that you would like to see done 
soon, but you're comfortable with them happening after the merge, please 
share those items as well). Our Flang community technical call on Monday 
morning will be dedicated to forming a concrete plan from any 
yet-unaddressed items and making sure that we have a checklist to address.

Thanks again,


On 1/8/20 1:01 PM, Renato Golin wrote:
> On Wed, 8 Jan 2020 at 01:48, Eric Christopher via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> I am in favor of having a flang front end in tree. I have concerns about the design of flang versus other front ends, the lack of llvm based library use, and a number of other things that I tried to enumerate in previous emails. I don't know if anything has changed and the responses I got back originally were "we're going to do it anyway" so it didn't leave much room for engagement.
> (Disclaimer: Not taking sides, I have no stake in Flang or Fortran).
> I think David's comparison to LLDB is interesting. It started very
> distant, and then with time merged with the codebase and now it's a
> full fledged LLVM project.
> The current Flang (F18) is meant to be much closer to LLVM than the
> previous one, and the whole mindset was afaik to keep it that way. In
> the same way that LLDB once was.
> I do agree with Hal that there is a small but significant overlap of
> communities, and I do agree with Rick that the longer it stays
> separate, the harder it will be for that sub-community.
> But LLDB started at a time where "being an LLVM project" was mostly
> about being in our SVN repo. There was no mono-repo, and the cost of
> being there was lower-ish.
> I believe that can be solved with build semantics (CMake stuff?), not
> a big problem, so the main issue is about community: will the project
> move fast enough towards LLVM integration or will it dangle with
> downstream implementations and be mostly useless upstream?
> I think we have enough people that care about Flang publicly putting
> their names forward. This makes me assume the former, so I'm
> personally ok with the merge.
> If it happens before the current branch or not, will depend on how
> fast they're willing to work towards a working Fortran front-end.
> I'd assume that, once it's in, the next release (July/20) would have
> to have something minimally decent. But that's not a strong opinion,
> so, salt & pepper.
> cheers,
> --renato

Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory

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