Install docc for C/C++

docc is a drop-in replacement for clang and gcc. In this Quickstart, you install it, compile a small vector kernel, and then run that kernel on all CPU cores and on a GPU without changing the code.

Requirements

Component	Requirement
Operating system	Ubuntu 24.04 (x86-64, arm64), Ubuntu 26.04, Debian 13, RHEL 10 (x86-64)
LLVM/Clang	21, from the official LLVM repository
NVIDIA GPUs	CUDA toolkit in /usr/local/cuda (only for -docc-tune=cuda)
AMD GPUs	ROCm in /opt/rocm or $ROCM_PATH (only for -docc-tune=rocm)
Tenstorrent	TT-Metalium, located via $TT_METAL_INSTALL_DIR or $TT_METAL_HOME (only for -docc-tune=tenstorrent)

Install

1. Install LLVM 21 from the official repository so that it does not conflict with your distribution's default LLVM:

   wget https://apt.llvm.org/llvm.sh
   chmod +x llvm.sh
   sudo ./llvm.sh 21

2. Download the package for your distribution from the Daisytuner website and install it:

   # Debian / Ubuntu
   sudo apt-get install ./docc_*.deb
   
   # RHEL
   sudo dnf install ./docc-*.rpm

3. Check the installation:

   docc --version

The package installs the compiler drivers docc (C, like clang) and docc-cpp (C++, like clang++), together with the linker wrapper docc-ld and the runtime libraries.

Prepare GPU targets (optional)

docc detects the first GPU in your system and compiles for its architecture. To compile for a different GPU, for example on a build machine without a GPU, set the architecture explicitly:

export DOCC_CUDA_ARCH=sm_90     # NVIDIA H100
export DOCC_ROCM_ARCH=gfx942    # AMD MI300

Next step

Continue with Run Your First Code to compile and accelerate the running example of this guide.