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.
- Project title
Compile programs with LLVM compiler
LLVM 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. 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 .
The complete project proposal is available here .
· 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
- 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
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.
- Project plan
The basic steps in this project are listed below.
Compile the Ubuntu distribution in gcc and LLVM
If the compilation succeeds convert the build system to LLVM Program testsuite compatible mode
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
Build an image from projects successfully built with LLVM and merge in projects built with gcc in 3.c
Try to boot the image from step 4 and track the problems.
Continue the process until step 2 works.
According to these steps I can break down this project in to three major phases
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
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
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
I am a final year student of the Department of Computer Science and Engineering, University of Moratuwa, Sri Lanka. 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.
For further information you can refer my resume .
 - http://llvm.org/