Clang In Browser (cib)

Try it at https://tbfleming.github.io/cib/

I'm trying to see how far wasm can go. Is it possible to compile clang to wasm and have it generate code within the browser?

Current status:

• Works in Firefox 57 and Chrome 63
• clang-format: working
• clang: working for simple cases
• Running generated wasm: working for simple cases

Currently missing:

• Global constructors and destructors
• Standard library globals (e.g. cin, cout)
• RTTI, exception handling

VM for building clang

• Create a fresh VM to build with. The build will probably fail if you already have emscripten or clang installed.
• Consider using a high thread-count VM; e.g. an EC2 c5.9xlarge.
• I put the repo in a dedicated volume while building; this aids using spot instances. 100 GB.

Ubuntu 16.04:

sudo apt update
sudo apt upgrade
sudo apt install build-essential cmake ninja-build python nodejs-legacy libncurses-dev

Building WASM binaries

./build.py -a

This script:

• Clones needed repos
• Builds an llvm toolchain for targeting WASM
• Builds emscripten
• Invokes emscripten to:
  • set up environment
  • build emscripten's dependances
• Uses emscripten to build llvm libraries
• Builds the apps