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:

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

2. (Temporary) Checkout temporary branch named 'build_llvm_project_repo_using_built_repo_compiler':

    $ cd llvm-project-prepo
    $ git checkout build_llvm_project_repo_using_built_repo_compiler
   

3. Clone pstore:

    $ git clone https://github.com/SNSystems/pstore.git
   

4. Build LLVM enabling the clang and pstore subprojects:

    $ 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

This task invokes:

1. compile the llvm-project-prepo project targeting the program repository using the initial repo compiler
2. convert the Repo ticket files to ELF object files using repo2obj
3. link the ELF object files to generate an executable ELF file
4. repeat the above steps once to verity database (i.e. all fragments are in the database)

1. Copy the repo.json to a parent directory of your llvm-project-prepo build directory, for example, your local llvm-project-prepo repository.

    $ 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 the standard 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. clean/delete all ticket files (retain the clang.db database) and build the project again (for the second time build: all fragments will be in the database.)

    $ ninja clean
    $ ninja
   

Running unit and regression tests

Run the LLVM and Clang tests for build. For a debug build, currently there are 30552 tests passed out of 30567 tests (99.95%). Currently for the release build, there are 30583 tests passed out of 30717 tests (99.56%).

	$ 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