[LLVMdev] Proposal for GSoc project - Compile programs with LLVM compiler

Mon Mar 31 04:23:08 PDT 2008

hello everybody,

I'm planning to compile a large codebase (Ubuntu) with LLVM compiler as my
GSoc project 2008. I've given the my proposal below. I'll be really great
full  if you can provide  your feedback on improving this proposal.

1. Project title

Compile programs with LLVM compiler

2. Abstract

LLVM[1] is a Low Level Virtual Machine. It basically consists of two
modules. They are the LLVM suite which consists of all the tools, libraries
and header files needed to use the low level virtual machine and the GCC
front end. The GCC front end contains a version of GCC that compiles C and
C++ code in to LLVM bitcode. There is a third, optional piece called
llvm-test. It is a suite of programs with a testing harness that can be used
to further test LLVM's functionality and performance.

The main objective of this project is to improve the LLVM testsuite[2].  The
basic approach followed in achieving this objective is compiling a large
code base that has not yet been compiled with LLVM and converts the build
system to be compatible with build system of the LLVM testsuite.

In this project Ubuntu is used as the code base and initially it will be
built using LLVM. Then the build system is tested and files bug reports for
any issues that might hit and help track down problems.

The development progress can be tracked from here [3].

The complete project proposal is available here [4].

3. Deliverables

·         Updated build system

·         Bugs reported to the bug tracker

·         Document (associated work)

·         Improved test programs

·         A guide for future continuation of this project or similar
projects

4. Benefits to the LLVM community

The following will be available to the LLVM community on successful
completion of the project.

·         An improved testsuite

·         A guide (document) to follow similar projects in future

 5. Overview

This section contains my work in this project.

The main task is to build the entire Ubuntu distribution in LLVM. This will
add new testcases and benchmarks for the use of LLVM.  A large testsuite is
very important since it provides a lot of coverage of programs and enables
us to spot and improve any problematic areas in the compiler.

The procedure followed in this project is discussed below.

Initially the entire Ubuntu distribution will be compiled with the LLVM. If
the compilation fails then the set of projects that successfully build with
LLVM will be selected.  Bugs are filed for the projects that fail with
reduced testcases.  If the compilation succeeds the build system will be
converted to be compatible with the LLVM Programs testsuite. This can be
checked in to SVN and the automated tester can use it to track progress of
the compiler.

The next step is to build an image from projects that are successfully built
with LLVM and merge projects built with gcc for those who failed in LLVM.  Then
this image is booted and the problems that encounter during this process
will be tracked down.  This process will be repeated until the entire system
is successfully built with LLVM and booted as expected.

When testing the code, it can be run with a variety of optimizations, and
with all the back-ends: CBE, llc, and lli.

6. Project plan

The basic steps in this project are listed below.

1.       Compile the Ubuntu distribution in gcc and LLVM

2.       If the compilation succeeds convert the build system to LLVM
Program testsuite compatible mode

3.       If fails,

a.       File bugs

b.       Compile project by project in LLVM and select the projects that
successfully compiles in LLVM.

c.       For the projects that fail in LLVM compile them in gcc

4.       Build an image from projects successfully built with LLVM and merge
in projects built with gcc in 3.c

5.       Try to boot the image from step 4 and track the problems.

6.       Continue the process until step 2 works.

According to these steps I can break down this project in to three major
phases

1st Phase

Compile Ubuntu distribution in gcc and LLVM. This is the first most steps
and it will require about 3 weeks.

Estimated completion: 20th May 2008

2nd Phase

If compilation fails follow steps 2,3,4,5. These steps are followed
iteratively depending on the output. When following these steps for the
first time it requires a lot of time. Therefore this part of the project
will consume a lot of time provided that the 1st step fails.

Deliverables: A report of bugs

Estimated completion: 14th July 2008

3rd Phase

This is the final phase. This involves converting the build system to be
compatible with the LLVM Programs testsuite.

Deliverables: A report of bugs, document (associated work), and improved
test programs, updated build system, document (if anyone needs to continue
this project this document will be supportive)

Estimated completion: 20th August 2008

7 Biography

I am a final year student of the Department of Computer Science and
Engineering, University of Moratuwa, Sri Lanka[5]. This is the first time
I'm getting involved in an open source project. But I'm highly impressed in
open source project model and planning to get involved in more projects in
future.

I have special interests in compiler technology and I have experience in C,
C++ and Java programming languages. I have developed a lexical analyzer in C
for Javascript language [6] and a Javascript pretty printer is also
developed in python [7]. I find this project to be interesting since it
requires knowledge regarding compiler technology and I will continue to work
on this area to make further contributions to the LLVM community in future.

For further information you can refer my resume [8].

References

[1] - http://llvm.org/

[2] - http://llvm.org/docs/TestingGuide.html

[3]- http://llvmcompiler.blogspot.com/

[4] -
http://llvmcompiler.blogspot.com/2008/03/proposal-for-summer-of-code-2008.html

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

[6]- http://paba50.googlepages.com/LexicalAnalizer.zip

[7]- http://paba50.googlepages.com/PrettyPrinter.zip

[8]- http://paba50.googlepages.com/Paba-resume.pdf
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