wasm modules as dynamic modules with import support

Author: guybedford

lib/internal/modules/cjs/loader.js

@@ -643,7 +643,7 @@ Module.prototype.load = function(filename) {
         url,
         new ModuleJob(ESMLoader, url, async () => {
           return createDynamicModule(
-            ['default'], url, (reflect) => {
+            [], ['default'], url, (reflect) => {
               reflect.exports.default.set(exports);
             });
         })

lib/internal/modules/esm/create_dynamic_module.js

@@ -1,14 +1,18 @@
 'use strict';
 
-const { ArrayPrototype } = primordials;
+const { ArrayPrototype, JSON, Object } = primordials;
 
 const debug = require('internal/util/debuglog').debuglog('esm');
 
-const createDynamicModule = (exports, url = '', evaluate) => {
+const createDynamicModule = (imports, exports, url = '', evaluate) => {
   debug('creating ESM facade for %s with exports: %j', url, exports);
   const names = ArrayPrototype.map(exports, (name) => `${name}`);
 
   const source = `
+${ArrayPrototype.join(ArrayPrototype.map(imports, (impt, index) =>
+    `import * as $import_${index} from ${JSON.stringify(impt)};
+import.meta.imports[${JSON.stringify(impt)}] = $import_${index};`), '\n')
+}
 ${ArrayPrototype.join(ArrayPrototype.map(names, (name) =>
     `let $${name};
 export { $${name} as ${name} };
@@ -22,19 +26,22 @@ import.meta.done();
 `;
   const { ModuleWrap, callbackMap } = internalBinding('module_wrap');
   const m = new ModuleWrap(source, `${url}`);
-  m.link(() => 0);
-  m.instantiate();
 
   const readyfns = new Set();
   const reflect = {
-    namespace: m.namespace(),
-    exports: {},
+    namespace: undefined,
+    exports: Object.create(null),
     onReady: (cb) => { readyfns.add(cb); },
   };
 
+  if (imports.length)
+    reflect.imports = Object.create(null);
+
   callbackMap.set(m, {
     initializeImportMeta: (meta, wrap) => {
       meta.exports = reflect.exports;
+      if (reflect.imports)
+        meta.imports = reflect.imports;
       meta.done = () => {
         evaluate(reflect);
         reflect.onReady = (cb) => cb(reflect);

lib/internal/modules/esm/create_wasm_module.js

@@ -153,7 +153,7 @@ class Loader {
       loaderInstance = async (url) => {
         debug(`Translating dynamic ${url}`);
         const { exports, execute } = await this._dynamicInstantiate(url);
-        return createDynamicModule(exports, url, (reflect) => {
+        return createDynamicModule([], exports, url, (reflect) => {
           debug(`Loading dynamic ${url}`);
           execute(reflect.exports);
         });

lib/internal/modules/esm/loader.js

@@ -4,6 +4,7 @@
 
 const {
   JSON,
+  Object,
   SafeMap,
   StringPrototype
 } = primordials;
@@ -17,8 +18,6 @@ const CJSModule = require('internal/modules/cjs/loader');
 const internalURLModule = require('internal/url');
 const createDynamicModule = require(
   'internal/modules/esm/create_dynamic_module');
-const createWASMModule = require(
-  'internal/modules/esm/create_wasm_module');
 const fs = require('fs');
 const { fileURLToPath, URL } = require('url');
 const { debuglog } = require('internal/util/debuglog');
@@ -76,11 +75,11 @@ translators.set('commonjs', async function commonjsStrategy(url, isMain) {
   ];
   if (module && module.loaded) {
     const exports = module.exports;
-    return createDynamicModule(['default'], url, (reflect) => {
+    return createDynamicModule([], ['default'], url, (reflect) => {
       reflect.exports.default.set(exports);
     });
   }
-  return createDynamicModule(['default'], url, () => {
+  return createDynamicModule([], ['default'], url, () => {
     debug(`Loading CJSModule ${url}`);
     // We don't care about the return val of _load here because Module#load
     // will handle it for us by checking the loader registry and filling the
@@ -101,7 +100,7 @@ translators.set('builtin', async function builtinStrategy(url) {
   }
   module.compileForPublicLoader(true);
   return createDynamicModule(
-    [...module.exportKeys, 'default'], url, (reflect) => {
+    [], [...module.exportKeys, 'default'], url, (reflect) => {
       debug(`Loading BuiltinModule ${url}`);
       module.reflect = reflect;
       for (const key of module.exportKeys)
@@ -120,7 +119,7 @@ translators.set('json', async function jsonStrategy(url) {
   let module = CJSModule._cache[modulePath];
   if (module && module.loaded) {
     const exports = module.exports;
-    return createDynamicModule(['default'], url, (reflect) => {
+    return createDynamicModule([], ['default'], url, (reflect) => {
       reflect.exports.default.set(exports);
     });
   }
@@ -140,7 +139,7 @@ translators.set('json', async function jsonStrategy(url) {
     throw err;
   }
   CJSModule._cache[modulePath] = module;
-  return createDynamicModule(['default'], url, (reflect) => {
+  return createDynamicModule([], ['default'], url, (reflect) => {
     debug(`Parsing JSONModule ${url}`);
     reflect.exports.default.set(module.exports);
   });
@@ -151,11 +150,21 @@ translators.set('wasm', async function(url) {
   const pathname = fileURLToPath(url);
   const buffer = await readFileAsync(pathname);
   debug(`Translating WASMModule ${url}`);
+  let compiled;
   try {
-    const compiled = await WebAssembly.compile(buffer);
-    return createWASMModule(compiled, url);
+    compiled = await WebAssembly.compile(buffer);
   } catch (err) {
     err.message = pathname + ': ' + err.message;
     throw err;
   }
+
+  const imports =
+      WebAssembly.Module.imports(compiled).map(({ module }) => module);
+  const exports = WebAssembly.Module.exports(compiled).map(({ name }) => name);
+
+  return createDynamicModule(imports, exports, url, (reflect) => {
+    const { exports } = new WebAssembly.Instance(compiled, reflect.imports);
+    for (const expt of Object.keys(exports))
+      reflect.exports[expt].set(exports[expt]);
+  });
 });

lib/internal/modules/esm/translators.js

@@ -149,7 +149,6 @@
       'lib/internal/modules/cjs/loader.js',
       'lib/internal/modules/esm/loader.js',
       'lib/internal/modules/esm/create_dynamic_module.js',
-      'lib/internal/modules/esm/create_wasm_module.js',
       'lib/internal/modules/esm/default_resolve.js',
       'lib/internal/modules/esm/module_job.js',
       'lib/internal/modules/esm/module_map.js',