[LLVMdev] [GSoC] Flang's end of GSoC report

Chris Lattner clattner at apple.com
Mon Sep 23 13:37:56 PDT 2013

On Sep 23, 2013, at 10:44 AM, C. Bergström <cbergstrom at pathscale.com> wrote:
>> I'm not sure what business advantage you think that a fortran frontend would give you, but you should carefully consider what you think you're achieving.
> Ok - thanks for that insightful heads up. It's not really Apples vs Apples though. OpenCL has multiple companies working on it, but for Fortran - who are "all the vendors"... (Fortran has been around *a lot* longer - it's not like new players are popping up every month)
> ---------
> In the past couple of years - I've been an advocate of a Fortran-clang front-end, but until recently it wasn't very active. No magic community formed and really who cares? (devils advocate hat on) Besides ANL - who will the potential users be? (Honest question to anyone reading this)

I think you have some fundamental misunderstandings of how open source software works in practice.  You don't magically get dozens of contributors contributing patches the day you open your doors.

LLDB, for example, took over a year and a half of development in public before the community really started growing around it.  Fostering an open source community is a lot of work, and a long term play.

> On a more technical note - flang is not upstream friendly "right now" (imho). The technical issues with integrating it cleanly into clang upstream are and will be worked out. I think if we do move to an open development model we need to be working on clang master. This will get the project more exposure as well make it easier for people to test.
> Fortran is totally non-c-family - It's like trying to add Python, Java or COBAL - It gets even more complicated with things like module formats, CAF and arrays. When we try to upstream our patches - who will review them? Will it be like OpenMP where things get bottlenecked waiting on reviews for (months/weeks). (This may tie into who will the users be and the overall general community interest)

I'm fine with flang either becoming part of LLVM in time, or being separate.  I'm fine with you guys reviewing your own patches, etc.  I'm just advocating that you keep the frontend public.


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