Build and install

CIR is enabled by setting the cmake variable CLANG_ENABLE_CIR to ON, note that it requires both mlir and clang projects to be enabled. Other than that it works with a regular build of Clang/LLVM.

... -DLLVM_ENABLE_PROJECTS="clang;mlir;..." -DCLANG_ENABLE_CIR=ON...

See the steps here for general instruction on how to build LLVM.

For example, building and installing CIR enabled clang on macOS could look like:

CLANG=`xcrun -f clang`
INSTALLDIR=/tmp/install-llvm

$ cd llvm-project/llvm
$ mkdir build-release; cd build-release
$ /Applications/CMake.app/Contents/bin/cmake -GNinja \
 -DCMAKE_BUILD_TYPE=Release \
 -DCMAKE_INSTALL_PREFIX=${INSTALLDIR} \
 -DLLVM_ENABLE_ASSERTIONS=ON \
 -DLLVM_TARGETS_TO_BUILD="host" \
 -DLLVM_ENABLE_PROJECTS="clang;mlir" \
 -DCLANG_ENABLE_CIR=ON \
 -DCMAKE_CXX_COMPILER=${CLANG}++ \
 -DCMAKE_C_COMPILER=${CLANG} ../
$ ninja install
  

Check for cir-opt to confirm all is fine:

$ /tmp/install-llvm/bin/cir-opt --help