Building on Windows

Building LLVM+MLIR on Windows

MSVC is installed and available.

Make sure you build x64 LLVM if Rust is targeting x64.

Execute these commands in a Developer Command Prompt for VS 2022 or similar.

These instructions are for LLVM 22.x and will install LLVM to C:\llvm-install

git clone  --depth 1 --branch llvmorg-22.1.7 https://github.com/llvm/llvm-project.git

cd llvm-project

cmake -S llvm -B build `
  -DCMAKE_INSTALL_PREFIX="C:\llvm-install" `
  -DLLVM_ENABLE_PROJECTS="mlir;clang" `
  -DLLVM_TARGETS_TO_BUILD="Native;NVPTX" `
  -DCMAKE_BUILD_TYPE=Release `
  -Thost=x64 `
  -DLLVM_ENABLE_ASSERTIONS=ON

cmake --build build --config Release --target install

Environment Variables

Set the following environment variables

$env:LLVM_SYS_221_PREFIX="C:\llvm-install"
$env:MLIR_SYS_220_PREFIX="C:\llvm-install"
$env:MLIR_SYS_221_PREFIX="C:\llvm-install"
$env:TABLEGEN_220_PREFIX="C:\llvm-install"
$env:PATH = "C:\llvm-install\bin;" + $env:PATH

libclang.dll is found through llvm-config on the path, so LIBCLANG_PATH is only needed to point bindgen at a different one.