Cheerp is composed of multiple components, they are somewhat interdependent and should be built together. This build instructions are for building the latest stable release, Cheerp 2.7.


We assume that you have git, cmake, python and a modern C++ compiler properly installed. Example, using apt-get:

apt-get install cmake python3 python3-distutils ninja-build gcc lld git

Get the sources

You need to get all the sources first. Please define the CHEERP_SRC environment variable that will be used in various commands.

mkdir cheerp
cd cheerp
git clone --branch cheerp-2.7
git clone --branch cheerp-2.7
git clone --branch cheerp-2.7
git clone --branch cheerp-2.7

Build Cheerp compiler

cd cheerp-compiler
cmake -S llvm -B build -C llvm/CheerpCmakeConf.cmake -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS=clang -G Ninja
ninja -C build -j4
ninja -C build install
cd ..

By default Cheerp will be installed in /opt/cheerp, with the main executable at /opt/cheerp/bin/clang++. If you need write privileges to /opt/cheerp, then prepend all install commands with sudo.

Build utilities and libraries

cd cheerp-utils
cmake -B build -DCMAKE_INSTALL_PREFIX=/opt/cheerp .
make -C build install
cd ..

cd cheerp-newlib/newlib
mkdir build_genericjs
cd build_genericjs
../configure --host=cheerp-genericjs --with-cxx-headers=$PWD/../../cheerp-compiler/libcxx/include --prefix=/opt/cheerp --enable-newlib-io-long-long --enable-newlib-iconv --enable-newlib-iconv-encodings=utf-16,utf-8,ucs_2 --enable-newlib-mb --enable-newlib-nano-formatted-io AR=/opt/cheerp/bin/llvm-ar RANLIB="/opt/cheerp/bin/llvm-ar s"
make install
../ genericjs
cd ..
mkdir build_asmjs
cd build_asmjs
../configure --host=cheerp-asmjs --with-cxx-headers=$PWD/../../cheerp-compiler/libcxx/include --prefix=/opt/cheerp --enable-newlib-io-long-long --enable-newlib-iconv --enable-newlib-iconv-encodings=utf-16,utf-8,ucs_2 --enable-newlib-mb --enable-newlib-nano-formatted-io AR=/opt/cheerp/bin/llvm-ar RANLIB="/opt/cheerp/bin/llvm-ar s"
make install
../ asmjs
cd ..
cd ../..

cd cheerp-compiler
cmake -S runtimes -B build_runtimes_genericjs -GNinja -C runtimes/CheerpCmakeConf.cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_TOOLCHAIN_FILE="/opt/cheerp/share/cmake/Modules/CheerpToolchain.cmake"
ninja -C build_runtimes_genericjs
ninja -C build_runtimes_genericjs install

cmake -S runtimes -B build_runtimes_wasm -GNinja -C runtimes/CheerpCmakeConf.cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_TOOLCHAIN_FILE="/opt/cheerp/share/cmake/Modules/CheerpWasmToolchain.cmake"
ninja -C build_runtimes_wasm
ninja -C build_runtimes_wasm install
cd ..

cd cheerp-libs
make -C webgles install INSTALL_PREFIX=/opt/cheerp CHEERP_PREFIX=/opt/cheerp
make -C wasm install INSTALL_PREFIX=/opt/cheerp CHEERP_PREFIX=/opt/cheerp
make -C stdlibs install INSTALL_PREFIX=/opt/cheerp CHEERP_PREFIX=/opt/cheerp
cd ..

“Hello, World” in Cheerp

//save as example.cpp
#include <iostream>

int main()
    std::cout << "Hello, World!\n";
    return 0;

/opt/cheerp/bin/clang++ example.cpp -o cheerp_example.js -O3 && node cheerp_example.js Should compile and execute the relevant file.

Cheerp unit tests

cd cheerp-utils/tests
python /opt/cheerp/bin/clang++ node --all -j8

This command will compile and execute the Cheerp test suite.