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LLVM with Clang Build Instructions

This guide explains how to set up, build, and test LLVM with Clang on your local machine.

Prerequisites​

Before you start building LLVM and Clang, make sure the following software is installed:

  • CMake (version 3.13 or higher)
  • Ninja (recommended for faster builds)
  • Python (for running tests)
  • Git (optional for version control)

Installing Dependencies​

Linux
sudo apt-get install cmake ninja-build python3 git
Windows
note

With Visual Studio

With WSL
sudo apt update
sudo apt install build-essential cmake ninja-build python3

MacOS
brew install cmake ninja python git

Cloning the LLVM Project​

Clone the LLVM project from GitHub. This includes Clang and other subprojects

git clone https://github.com/llvm/llvm-project.git
cd llvm-project

If you want to build a specific release, check out the corresponding tag. For example:

git checkout llvmorg-16.0.0

Configuring the Build​

Create a separate directory for building the project:

mkdir build
cd build
Linux
cmake -G "Ninja" -DCMAKE_BUILD_TYPE=Release \
  -DLLVM_ENABLE_PROJECTS="clang;lld" \
  -DLLVM_TARGETS_TO_BUILD="X86;AMDGPU" \
  ../llvm

macOS
cmake -G "Ninja" -DCMAKE_BUILD_TYPE=Release \
  -DLLVM_ENABLE_PROJECTS="clang;lld" \
  -DLLVM_TARGETS_TO_BUILD="X86;AMDGPU" \
  ../llvm
Windows
cmake -G "Ninja" -DCMAKE_BUILD_TYPE=Release \
  -DLLVM_ENABLE_PROJECTS="clang;lld" \
  -DLLVM_TARGETS_TO_BUILD="X86;AMDGPU" \
  ../llvm
note

for the visual Studio

Configuring the Build​

Create a separate directory for building the project:

mkdir build
cd build
cmake -G Ninja -DLLVM_ENABLE_PROJECTS=clang -DCMAKE_BUILD_TYPE=Release ../llvm
note
  • -DLLVM_ENABLE_PROJECTS=clang: This enables Clang to be built alongside LLVM.
  • -DCMAKE_BUILD_TYPE=Release: Builds LLVM in release mode with optimizations.
  • -DLLVM_TARGETS_TO_BUILD=X86: You can specify the target architecture(s). Replace X86 with your desired architecture (e.g., ARM, AArch64).

For other Cmake flag please visit Configure the build using CMake. It's recommended to use Ninja as the build system for faster builds.

If on windows you are facing any issue with the ninja build try with the Visual studio build or use WSL

Building LLVM with Clang​

Once the configuration is complete, build the project:

ninja

If you are not using Ninja, you can use Make instead:

make

The build process can take some time depending on your machine's specifications.

Running Tests​

After the build is complete, you can run the tests to ensure everything is working correctly:

ninja check-all

This command will run all available tests for LLVM, Clang, and other enabled subprojects.

Cleaning Up the Build​

To clean the build directory, run:

ninja clean

Or with Make:

make clean

Short Summary​

  1. Prerequisites: Install CMake, Ninja, Python, and Git.

  2. Install Dependencies:

    • Linux: 
      sudo apt-get install cmake ninja-build python3 git
    • Windows (WSL): 
      sudo apt update && sudo apt install build-essential cmake ninja-build python3
    • macOS: 
      brew install cmake ninja python git

  3. Clone the LLVM Project:

    git clone https://github.com/llvm/llvm-project.git
    cd llvm-project
    git checkout llvmorg-1.0.0  # Optional for specific version

  4. Configure and Build

mkdir build
cd build
cmake -G "Ninja" -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_TARGETS_TO_BUILD="X86;AMDGPU" ../llvm
ninja

Additional Resources​

For more details, refer to the official LLVM documentation: