/LLVM-Intro-Function-Pass

An LLVM-based project which warns developers if they have any function in their C/C++ code that has more than three parameters

Primary LanguageC++MIT LicenseMIT

LLVM Intro Function Pass

It is an LLVM-based project which warns developers if they have any method in their C/C++ code that has more than three parameters. It is an introductory project which utilizes LLVM compiler infrastructure.

Environment Setup for the First Time

Here is my first-time environment setup which I have used for this project:

  • Operating system: Ubuntu 18.04 LTS

  • Commands to setup LLVM: To setup LLVM on my Ubuntu machine, I have used the following commands:

    • To update and upgrade repositories: 
      sudo apt-get update
sudo apt-get upgrade
    • To install LLVM and Clang: 
      sudo apt-get install clang-6.0 lldb-6.0 lld-6.0
sudo apt-get install llvm
sudo apt-get install clang
sudo apt-get install clang-tools
    • To install CMake and other build tools: 
      sudo apt-get install build-essential
sudo apt-get install cmake

  • Test whether the setup done correctly: I have used the following commands to test whether the environment setup has been done correctly:

    username@PC-NAME:~$ llvm-config --version
6.0.0
username@PC-NAME:~$ llvm-config --prefix
/usr/lib/llvm-6.0
username@PC-NAME:~$ clang
clang: error: no input files
username@PC-NAME:~$

    Notice the output of each command.

Build LLVM Function Pass

  • Commands to build LLVM Function Pass: Notice that there is an LLVM function pass defined in /skeleton/Skeleton.cpp file. I have opened a terminal window outside of /skeleton directory. Then I have run the following commands:

    mkdir build
cd build/
cmake ..
make

    Notice that /build/skeleton/libSkeletonPass.so file has been generated.

  • Commands to use the LLVM Function Pass to compile code:

    • If you open /skeleton/Skeleton.cpp file, then you will see that SkeletonPass function pass actually warns developers if they have any function in their code that has more than three parameters.
    • Now notice that /HelloWorld.c file has a function called void concatCharArray(char *result, const char *a, const char *b, const char *c). So concatCharArray function has more than three arguments (four arguments).
    • I have used the following command to compile /HelloWorld.c file with SkeletonPass function pass: 
      username@PC-NAME:~/Desktop/LLVM Intro Function Pass/build$ clang -Xclang -load -Xclang skeleton/libSkeletonPass.so ../HelloWorld.c
Warning: 'concatCharArray' function has 4 arguments!
username@PC-NAME:~/Desktop/LLVM Intro Function Pass/build$
      Notice that the above console output shows a warning generated by SkeletonPass function pass.

  • Commands to run the compiled executable code: Since the compiled executable code of /HelloWorld.c has been created, I can use the following command to run it:

    username@PC-NAME:~/Desktop/LLVM Intro Function Pass/build$ ./a.out 
Hello World!
I am testing llvm!
username@PC-NAME:~/Desktop/LLVM Intro Function Pass/build$

Additional Resource