[LLVMdev] GSoC project questions.

[Alex L]

Hi again,

I was studying and building the lfort repository as I said I would do, but
after a while I decided that I would like to work on flang instead.
So, I forked flang and so far I've had pretty good success with it, here's
what I've done:
- Merged a pull request from a github user Michael Gottesman(He added
support for latest llvm and cmake)
- Fixed character literal continuation bug.
- Implemented INCLUDE statement (Only searches for files in -I dirs now)
- Implemented if-stmt(not the full if-construct yet).
You can see my repository here: https://github.com/hyp/flang

So far I've enjoyed working on flang, and I would like to apply to GSoC
with it. I will start writing a proposal in the next couple of days. Should
I send it to the mailing list first, or should I send it directly to GSoC?

Thanks.


2013/4/13 Alex L <arphaman at gmail.com>

> No. I think that you might want to use Clang for inspiration on design,
>> but you'd certainly not be bound to that. If you'd like to take a much more
>> start-from-scratch approach, you can also look at the code that Bill put
>> together: https://github.com/isanbard/flang - If you use that as a base,
>> we can always merge it with the useful lfort pieces later.
>
> Ok, that's good to know. In the next couple of days I will study the lfort
> repository more, and see if I can perhaps contribute a commit or two.
> Thankfully I know git and github and so that would make lfort really
> accessible for me.
>
>
> 2013/4/13 Hal Finkel <hfinkel at anl.gov>
>
>> ----- Original Message -----
>> > From: "Alex L" <arphaman at gmail.com>
>> > To: "Hal Finkel" <hfinkel at anl.gov>
>> > Cc: "Anton Korobeynikov" <anton at korobeynikov.info>, "Bill Wendling" <
>> isanbard at gmail.com>, "LLVM Developers Mailing
>> > List" <llvmdev at cs.uiuc.edu>
>> > Sent: Saturday, April 13, 2013 11:34:43 AM
>> > Subject: Re: [LLVMdev] GSoC project questions.
>> >
>> >
>> > Thanks for your replies.
>> > Working on the lfort compiler would certainly be an interesting
>> > project for me for this GSoC.
>>
>> Great!
>>
>> > I have studied lfort repository and
>> > commits, and I see that it has a lot of stuff for C/C++, am I
>> > correct that this is a fork of Clang? If this is correct, I wonder
>> > why this approach was chosen instead of starting out from scratch -
>> > is it because Clang already has a lot of code which can be reused
>> > for the Fortran compiler?
>>
>> Yes, lfort started out as a fork of Clang, but I don't think that is
>> overly relevant at this point. There are a few things from Clang that the
>> Fortran compiler could really reuse:
>>
>>  1. The driver/tools infrastructure (the code that finds the system
>> libraries, knows how to call the assembler, linker, etc.)
>>  2. The C preprocessor (in practice, a lot of Fortran code assumes the
>> existence of an integrated C preprocessor).
>>    2a. The lexical analysis framework, and to some extent, the classes
>> for printing nice error messages
>>  3. The directory layout and regression-testing setup
>>
>> At this point, I've pretty much finished taking advantage of all of those
>> pieces in lfort, and the remainder of the core code from Clang needs to be
>> replaced with Fortran-specific bits. Keeping the same general design
>> probably makes sense, but I could certainly be convinced otherwise.
>>
>> > I'm also unfamiliar with Clang and I was a
>> > bit overwhelmed when I saw the lfort repository at first because of
>> > this. If I were to work on this project, would I be required to use
>> > the Clang code?
>>
>> No. I think that you might want to use Clang for inspiration on design,
>> but you'd certainly not be bound to that. If you'd like to take a much more
>> start-from-scratch approach, you can also look at the code that Bill put
>> together: https://github.com/isanbard/flang - If you use that as a base,
>> we can always merge it with the useful lfort pieces later.
>>
>> Thanks again,
>> Hal
>>
>> >
>> >
>> >
>> > 2013/4/13 Hal Finkel < hfinkel at anl.gov >
>> >
>> >
>> >
>> > ----- Original Message -----
>> > > From: "Anton Korobeynikov" < anton at korobeynikov.info >
>> >
>> > > To: "James Courtier-Dutton" < james.dutton at gmail.com >
>> > > Cc: "Hal Finkel" < hfinkel at anl.gov >, "Bill Wendling" <
>> > > isanbard at gmail.com >, "LLVM Developers Mailing List"
>> > > < llvmdev at cs.uiuc.edu >
>> >
>> > > Sent: Saturday, April 13, 2013 9:12:39 AM
>> > > Subject: Re: [LLVMdev] GSoC project questions.
>> > >
>> >
>> > > > I agree that creating a complete Fortran compiler is a huge
>> > > > effort.
>> > > > But what about approaching it from a test driven development
>> > > > perspective?
>> > > > We start with a few small Fortran programs as "test cases".
>> > > > The GSoC task then gives the task as getting test case 1 to work.
>> > > > We could also apply this of "lfort". Determine a test case that
>> > > > currently
>> > > > fails on lfort, and ask the GSoC task to pass the test.
>> > > All this make sense only if there is interested party in long-term
>> > > development and maintenance. Otherwise the code will bitrot really
>> > > quickly and thus will be waste of time and money. Is there such a
>> > > party?
>> >
>> > I am certainly interested in long-term development and maintenance. I
>> > think that the first step toward making a useful Fortran compiler is
>> > this:
>> >
>> > 1. It should be able to compile BLAS: http://www.netlib.org/blas/
>> > (these are Fortran 77, and have no I/O, so should be relatively
>> > simple)
>> >
>> > 2. If that is complete, then move on to LAPACK:
>> > http://www.netlib.org/lapack/index.html (these use some subset of
>> > Fortran 90)
>> >
>> > As you can see from the test cases currently in lfort, most of the
>> > driver functionality and lexical analysis (for both Fortran 77 and
>> > 90) is done, and I've started on parsing (and semantic analysis and
>> > codegen for) variable declarations and some simple statements. I
>> > think that a motivated student could make a lot of headway, and
>> > should be able to at least finish step 1. Thoughts?
>> >
>> > -Hal
>> >
>> >
>> >
>> > >
>> > > --
>> > > With best regards, Anton Korobeynikov
>> > > Faculty of Mathematics and Mechanics, Saint Petersburg State
>> > > University
>> > >
>> > _______________________________________________
>> > LLVM Developers mailing list
>> > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu
>> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>> >
>> >
>>
>
>
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