Build LLVM with the Repo Compiler

This page shows how to build the llvm-project-prepo project from source then use the resulting compiler to re-build LLVM on Linux.

Building the initial repo compiler

1. Clone llvm-project-prepo repository.

    $ cd  $REPO_DIR
    $ git clone https://github.com/SNSystems/llvm-project-prepo.git
   

2. (Temporary step) Checkout the branch named 'build_llvm_project_repo_using_built_repo_compiler'.

    $ cd $REPO_DIR/llvm-project-prepo
    $ git checkout build_llvm_project_repo_using_built_repo_compiler
   

3. Clone pstore.

    $ cd $REPO_DIR/llvm-project-prepo
    $ git clone https://github.com/SNSystems/pstore.git
   

4. Build LLVM enabling the clang and pstore subprojects.

    $ cd $REPO_DIR/llvm-project-prepo
    $ mkdir build && cd build
    $ cmake -G "Ninja"  -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang;pstore" -DLLVM_TARGETS_TO_BUILD=X86 -DLLVM_TOOL_CLANG_TOOLS_EXTRA_BUILD=OFF ../llvm
    $ ninja
   

Using the initial repo compiler to build LLVM

• Compile the llvm-project-prepo project targeting the program repository using the initial repo compiler.
• Convert the Repo ticket files to ELF object files using repo2obj.
• Link the ELF object files to generate an executable ELF file.
• Repeat the above steps once to verity database (i.e. all fragments are in the database).

1. Copy the repo.json to any parent directory of $REPO_DIR/llvm-project-prepo/build.

    $ cd llvm-project-prepo
    $ cp ./llvm/utils/repo/repo.json .		
    $ less repo.json
    {
    	"ar": "/usr/bin/ar",
    	"link": "/usr/bin/clang++",
    	"repo2obj": "/point/to/the/repo2obj/tool/in/llvm-pstore/build/directory"
    }
   

2. Continue to use your default ar and clang++ for the archiving and linking because the repo toolchain currently only supports the compilation. Modify the repo2obj option to point to the repo2obj tool in your build directory. Note: it must be an absolute path. e.g.

    "repo2obj": "/home/username/llvm-project-prepo/build/bin/repo2obj"
   

3. Generate a release build using the repo.cmake toolchain file.

    $ cd llvm-project-prepo
    $ mkdir build_repo_release && cd build_repo_release
    $ cmake -G "Ninja" -DCMAKE_BUILD_TYPE=Release -DLLVM_TARGETS_TO_BUILD=X86 -DLLVM_ENABLE_PROJECTS="clang;pstore"  -DLLVM_TOOL_CLANG_TOOLS_EXTRA_BUILD=OFF  -DPSTORE_ENABLE_BROKER=OFF -DLLVM_DISABLE_DYNAMIC_LIBRARY_UNITTEST=ON -DCMAKE_TOOLCHAIN_FILE=/home/username/github/llvm-project-prepo/llvm/utils/repo/repo.cmake -DCMAKE_CXX_COMPILER=/home/username/github/llvm-project-prepo/build/bin/clang++ -DCMAKE_C_COMPILER=/home/username/github/llvm-project-prepo/build/bin/clang -Dutils_dir=/home/username/github/llvm-project-prepo/llvm/utils/repo ../llvm
   
    You must specify for cmake:
        1. -DPSTORE_ENABLE_BROKER=OFF
            Disable the pstore broker projects since the repo compiler currently does not support exception handling
        2. -DLLVM_DISABLE_DYNAMIC_LIBRARY_UNITTEST=ON
            Disable the dynamic library unittests [issue12](https://github.com/SNSystems/llvm-project-prepo/issues/12)
        3. -DCMAKE_TOOLCHAIN_FILE=/home/username/github/llvm-project-prepo/llvm/utils/repo/repo.cmake
        4. -DCMAKE_CXX_COMPILER=/home/username/github/llvm-project-prepo/build/bin/clang++
        5. -DCMAKE_C_COMPILER=/home/username/github/llvm-project-prepo/build/bin/clang 
            Both CMAKE_CXX_COMPILER and DCMAKE_C_COMPILER are pointing to the initial repo compiler.
        6. -Dutils_dir=/home/username/github/llvm-project-prepo/llvm/utils/repo
            Specify the repo utilities directory, which contains additional scripts requied for the build.
   
    $ ninja
   

4. To rebuild, you can clean/delete all ticket files. All code fragments will be retained within the database (clang.db).

    $ ninja clean
    $ ninja
   

Running unit and regression tests

Currently, for a debug build, there are 30552 tests passed out of 30567 tests (99.95%) and for the release build, there are 30583 tests passed out of 30717 tests (99.56%). The issues found by the failing tests are being worked on.

	$ ninja check-all

Current build status

The llvm-project-prepo has been built and run with the tests twice in debug and release configurations.

Debug build with compiler switches: -O0 -fno-exceptions -fno-rtti.

Release build with compiler switches: -O3 -fno-exceptions -fno-rtti.

Configuration	1st build	1st run test	2nd build	2nd run test
Debug	✔	99.95% tests passed	✔	99.95% tests passed
Release	✔	99.56% tests passed	✔	99.56% tests passed