llvm dev - Mar 2008 - [LLVMdev] Compile programs with the LLVM Compiler as a gsoc project

hi,

This e-mail is written to involve some of the project ideas in LLVM in
GSOC this year.

I was looking in to the ideas mentioned under improving current system and
found the idea of "Compile programs with the LLVM Compiler" to be
interesting. I would like to compile one of the large code bases that have
not yet been compiled with LLVM and convert the build system to be
compatible with the LLVM Programs testsuite.



But I have several doubts to be clarified. They are listed below.

   - I would like to know whether this is a suitable project for GSOC?
   - What software has already been compiled with LLVM and what are not;
   so that I can identify the possible candidates for the project?



Thank you



Me:

My name is Kumaripaba Atukorala and I am a computer science and engineering
undergraduate [1]. I'm interested in compiler technology and have experience
in C/C++ and java programming [2].



[1] - http://www.cse.mrt.ac.lk

[2] - http://paba50.googlepages.com
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On Mar 29, 2008, at 11:53 PM, Kumaripaba Miyurusara Atukorala wrote:
> hi,
> This e-mail is written to involve some of the project ideas in LLVM  
> in GSOC this year.
> I was looking in to the ideas mentioned under improving current  
> system and found the idea of "Compile programs with the LLVM  
> Compiler" to be interesting. I would like to compile one of the  
> large code bases that have not yet been compiled with LLVM and  
> convert the build system to be compatible with the LLVM Programs  
> testsuite.
>
> But I have several doubts to be clarified. They are listed below.
> I would like to know whether this is a suitable project for GSOC?
> What software has already been compiled with LLVM and what are not;  
> so that I can identify the possible candidates for the project?
I think this would be a great project.  However, I would rephrase it  
to be more concrete.

How about taking a linux distro like redhat or gentoo or whatever you  
are familiar of comfortable with, and try compiling the whole thing  
with llvm-gcc?  As part of the GSoC project, you could file bug  
reports for any issues you hit and help track down problems.

-Chris
>
> Thank you
>
> Me:
> My name is Kumaripaba Atukorala and I am a computer science and  
> engineering undergraduate [1]. I'm interested in compiler technology  
> and have experience in C/C++ and java programming [2].
>
> [1] - http://www.cse.mrt.ac.lk
> [2] - http://paba50.googlepages.com
>
>
>
> _______________________________________________
> 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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Chris Lattner wrote:
>
> On Mar 29, 2008, at 11:53 PM, Kumaripaba Miyurusara Atukorala wrote:
>
>> hi,
>> This e-mail is written to involve some of the project ideas in LLVM
>> in GSOC this year.
>> I was looking in to the ideas mentioned under improving current
>> system and found the idea of "Compile programs with the LLVM
>> Compiler" to be interesting. I would like to compile one of the
large
>> code bases that have not yet been compiled with LLVM and convert the
>> build system to be compatible with the LLVM Programs testsuite.
>>
>>  
>>
>> But I have several doubts to be clarified. They are listed below.
>>
>>     * I would like to know whether this is a suitable project for GSOC?
>>     * What software has already been compiled with LLVM and what are
>>       not; so that I can identify the possible candidates for the
>>       project?
>>
> I think this would be a great project.  However, I would rephrase it
> to be more concrete.
>
> How about taking a linux distro like redhat or gentoo or whatever you
> are familiar of comfortable with, and try compiling the whole thing
> with llvm-gcc?  As part of the GSoC project, you could file bug
> reports for any issues you hit and help track down problems. 
>
Excellent idea!

When testing large code bases built with llvm, and trying to track down
where the problem is it would be very useful to have an automated tool
to help. Something similar to 'git bisect', or bugpoint but for many
source files.

For example: built entire code with gcc, get some "expected output"
(run
make check, ....), same for llvm-gcc. If they differ, start tracking
down (automatically!) in which source files the problem is.  Then you
build half code with llvm, half with gcc. If it breaks, you build 1/4
llvm, 3/4 gcc; if it doesn't break you build 3/4 llvm, 1/4 gcc, and so
on. The situation should be logged by a tool, because for example I
would certainly forget which build worked, and which one didn't.
It would make sense to cache files previously built, an easy way to do
that would be to build everything with one compiler, then backup&remove
one half, and built it with the other compiler (just run make with the
correct compiler, it will rebuild the missing files). Then restore the
half, remove a quarter, repeat.

If this tool could be a drop-in wrapper for CC/CXX, it would be
excellent, since nearly every autotooled package could be tested this way.

P.S.: to avoid duplicate bug reports, I think filing a "meta" bug that
holds as depedencies all bugs that affect package X would be useful.

Best regards,
--Edwin

Hi Chris,
> How about taking a linux distro like redhat or gentoo or whatever you
> are familiar of comfortable with, and try compiling the whole thing
> with llvm-gcc?  As part of the GSoC project, you could file bug
> reports for any issues you hit and help track down problems.
They may seem a bit large and daunting.  How about Linux from Scratch?
If it's completed, more could be added on.

    http://www.linuxfromscratch.org/

Cheers,


Ralph.

Hello,
> 1) I thought of taking the gcc compiler and compiling it with llvm
> since it is easier to make test cases to test the system. Is gcc
> compiler already built with llvm? if so I have the linux kernel as the
> second option. What is your openion on this ?
Just my 2 cents. I'd strongly suggest to select gentoo or anything
similar for this, it's pretty compiler-oriented, you can have several
versions of compilers in system and select, which compiler to use
smoothly.

-- 
With best regards, Anton Korobeynikov.

Faculty of Mathematics & Mechanics, Saint Petersburg State University.