YoWASP Clang/LLD package

This package provides a complete Clang/LLD toolchain built for WebAssembly and targeting WebAssembly as well. See the overview of the YoWASP project for details.

At the moment, this package only offers an API allowing to run Clang and LLD in a virtual filesystem; no executables are provided. Note that if you are importing .../gen/bundle.js directly, you must use it as a module.

Examples

All examples below are written for Node.js; to run them, install @yowasp/clang first. The C/C++ code can be compiled equally well in the browser and other runtimes, but WASI is unevenly supported.

Hosted C++ executable

import { runClang } from '@yowasp/clang';
const { meow } = await runClang(['clang++', 'test.cc', '-o', 'meow'],
    {"test.cc": `#include <iostream>\nint main() { std::cout << "meow++" << std::endl; }`});

import { WASI } from 'node:wasi';
const wasi = new WASI({ version: 'preview1' });
const module = await WebAssembly.compile(meow);
const instance = await WebAssembly.instantiate(module,
    {wasi_snapshot_preview1: wasi.wasiImport});
wasi.start(instance);
// prints "meow++"

Freestanding C library

import { runClang } from '@yowasp/clang';
const { 'a.out': wasm } = await runClang(['clang', '-nostdlib', '-Wl,--no-entry', 'test.c'], {
    'test.c': 'int add(int a, int b) __attribute__((export_name("add"))) { return a + b; }'});

const module = await WebAssembly.compile(wasm);
const instance = await WebAssembly.instantiate(module);
console.log('add(1, 2) =', instance.exports.add(1, 2));
// prints "add(1, 2) = 3"

API reference

This package provides two functions:

• runLLVM
  • The first argument is the utility to run: one of addr2line, ar, c++filt, dwarfdump, nm, objcopy, objdump, readobj, ranlib, size, strip, symbolizer, wasm-ld.
• runClang
  • The first argument is either clang or clang++.
  • Due to WASI limitations (an inability to spawn subprocesses), this function is a wrapper that parses the output of clang -### or clang++ -### to determine the sequence of processes to run. The parser was written with great care and handles many common exceptional conditions (e.g. the -help option), but the resulting function still deviates from how a standard Clang compiler driver would behave. Please report any deviations that impact your workflow as issues.

For more detail, see the documentation for the JavaScript YoWASP runtime.

Versioning

The version of this package is derived from the upstream LLVM package version in the X.Y.Z-S-M or X.Y.Z-M format, where the symbols are:

1. X: LLVM major version
2. Y: LLVM minor version
3. Z: LLVM patch version
4. S: gitK for unreleased LLVM snapshots, rcN for LLVM release candidates, not present for LLVM releases
5. M: package build version; disambiguates different builds produced from the same LLVM source tree

With this scheme, there is a direct correspondence between upstream versions and SemVer NPM package versions.

License

This package is covered by the Apache 2 license, which is the same as the (base) LLVM license.