micro:bit Clang/LLD WebAssembly package

Clang, LLD and the LLVM binutils as one WebAssembly binary that targets the BBC micro:bit's Cortex-M4, packaged with Arm Toolchain for Embedded's newlib-nano, libc++ and compiler-rt for that CPU. Runs in a browser, in Node and inside VS Code, and downloads nothing at runtime.

This is the compiler and its libraries only, the browser equivalent of installing arm-none-eabi-gcc. It knows nothing about CODAL; for that, see microbit-clang-wasm-codal.

The API runs the tools in a virtual filesystem and provides no executables. Files go in and come back out as a tree of Uint8Arrays. If you import .../gen/bundle.js directly, use it as a module.

import { commands } from 'microbit-clang-wasm';

const files = await commands['clang++'](
    ['-mcpu=cortex-m4', '-mthumb', '-mfpu=fpv4-sp-d16', '-mfloat-abi=softfp',
     '--sysroot=/usr', '-c', 'main.cpp', '-o', 'main.o'],
    { 'main.cpp': 'int main() { return 0; }' },
);

commands covers clang, clang++, ld.lld, wasm-ld, ar, ranlib, objcopy, objdump, strip, nm, readobj, size, c++filt, addr2line, symbolizer and dwarfdump. The sysroot travels with the package and is mounted at /usr; pass --sysroot=/usr explicitly rather than relying on a configuration file, which has no meaningful location in a virtual filesystem.

Derived from YoWASP/clang by Catherine (whitequark), which does the hard part of building LLVM for WASI. The compiler is LLVM under Apache-2.0 with LLVM exception; the runtime libraries carry Arm Toolchain for Embedded's own notices, libc++ and compiler-rt under Apache-2.0 with LLVM exception and newlib under several BSD-style notices.