Binaryen GC

Contains tools necessary for using Binaryen's GC API with javascript.

Includes a TypeBuilder for defining gc struct and array types, as well as a gc namespace for initializing and interacting said types.

Not affiliated with the official Binaryen project.

The bulk of this repo is a modified port of code from this PR to add support For GC to Binaryen JS. Permalink.

Inspiration was also taken from AssemblyScript's internal binaryen library and this comment.

API

See ./src/index.ts for the full API.

Example Usage

import { TypeBuilder, gc } from "binaryen-gc";
import binaryen from "binaryen";

// Simple Vec type { x: i32, y: i32, z: i32 }
const builder = new TypeBuilder(1);

builder.setStructType(0, [
  { type: binaryen.i32, packedType: 0, mutable: false },
  { type: binaryen.i32, packedType: 0, mutable: false },
  { type: binaryen.i32, packedType: 0, mutable: false },
]);

const types = builder.buildAndDispose();

const vecType = types.heapTypes[0];

// Simple module with a function that returns a Vec, and a main function that reads the x value
const mod = new binaryen.Module();
mod.setFeatures(binaryen.Features.All);

// Simple function that returns a Vec
mod.addFunction(
  "getVec",
  binaryen.none,
  binaryen.structref,
  [],
  mod.block(
    null,
    [
      gc.structs.newFromFields(mod, vecType, [
        mod.i32.const(1),
        mod.i32.const(2),
        mod.i32.const(3),
      ]),
    ],
    binaryen.auto
  )
);

// // Main function that reads the x value of the Vec
mod.addFunction(
  "main",
  binaryen.none,
  binaryen.structref,
  [],
  mod.call("getVec", [], binaryen.structref)
);

mod.addFunctionExport("main", "main");

mod.autoDrop();

mod.validate();

console.log(mod.emitText());