sbc100/wasm_ndk

This is temporary repo containing cmake toolchain for compiling code using Android NDK to WebAssembly. The project is currently in experimental stage so it would either be abandoned or merged to Android NDK in some way or form.

You will need Android NDK and since at the moment of writing this NDK toolchain does not support wasm target, - clang from Andorid OpenSource Project toolchain.

1. Download NDK here
2. Clone toolchain from this AOSP git repository:

   git clone --depth 1 https://android.googlesource.com/platform/prebuilts/clang/host/linux-x86
   

3. Set ANDROID_NDK_HOME environment variable to NDK root
4. Set ANDROID_CLANG_TOOLCHAIN environment variable to clang toolchain root (example: (toolchain repo root)/clang-r487747)

Go to cmake project and execute the following commands

mkdir build
cd build
cmake --toolchain $(wasm_ndk_root)/cmake/toolchain/android_wasm.toolchain.cmake ..
cmake --build .

The main document on how to build android llvm toolchain can be found here: https://android.googlesource.com/toolchain/llvm_android/

Before building add upstream remote to android llvm toolchain

cd toolchain/llvm-project
git remote add upstream https://github.com/llvm/llvm-project.git
git fetch upstream

create a local branch (for toolchain/llvm-project)

repo start upstream-patches .

The android toolchain is usually couple of month behind ToT - so these are cherry pick needed to build compilable wasm binaries

git cherry-pick cb5bc756808367d53c870716ce42611a563421e8

Use following command while building to exclude windows toolchain and skip tests

python toolchain/llvm_android/build.py --no-build windows --skip-tests