feat: Add __getFunction method for loader (#2037)

Author: MaxGraey

lib/loader/index.d.ts

@@ -82,6 +82,9 @@ export interface ASUtil {
   /** Gets a live view on a Float64Array's values in the module's memory. */
   __getFloat64ArrayView(ptr: number): Float64Array;
 
+  /** Gets a function from poiner which contain table's index. */
+  __getFunction(ptr: number): ((...args: unknown[]) => unknown) | null;
+
   /** Tests whether a managed object is an instance of the class represented by the specified base id. */
   __instanceof(ptr: number, baseId: number): boolean;
   /** Allocates a new string in the module's memory and returns a reference (pointer) to it. */

lib/loader/index.js

@@ -34,13 +34,22 @@ const ARRAYBUFFERVIEW_SIZE = 12;
 const ARRAY_LENGTH_OFFSET = 12;
 const ARRAY_SIZE = 16;
 
+const E_NO_EXPORT_TABLE   = "Operation requires compiling with --exportTable";
+const E_NO_EXPORT_RUNTIME = "Operation requires compiling with --exportRuntime";
+const F_NO_EXPORT_RUNTIME = () => { throw Error(E_NO_EXPORT_RUNTIME); };
+
 const BIGINT = typeof BigUint64Array !== "undefined";
 const THIS = Symbol();
 
 const STRING_SMALLSIZE = 192; // break-even point in V8
 const STRING_CHUNKSIZE = 1024; // mitigate stack overflow
 const utf16 = new TextDecoder("utf-16le", { fatal: true }); // != wtf16
 
+/** polyfill for Object.hasOwn */
+Object.hasOwn = Object.hasOwn || function(obj, prop) {
+  return Object.prototype.hasOwnProperty.call(obj, prop);
+};
+
 /** Gets a string from memory. */
 function getStringImpl(buffer, ptr) {
   let len = new Uint32Array(buffer)[ptr + SIZE_OFFSET >>> 2] >>> 1;
@@ -83,51 +92,44 @@ function preInstantiate(imports) {
   return extendedExports;
 }
 
-const E_NOEXPORTRUNTIME = "Operation requires compiling with --exportRuntime";
-const F_NOEXPORTRUNTIME = function() { throw Error(E_NOEXPORTRUNTIME); };
-
 /** Prepares the final module once instantiation is complete. */
 function postInstantiate(extendedExports, instance) {
   const exports = instance.exports;
   const memory = exports.memory;
   const table = exports.table;
-  const __new = exports.__new || F_NOEXPORTRUNTIME;
-  const __pin = exports.__pin || F_NOEXPORTRUNTIME;
-  const __unpin = exports.__unpin || F_NOEXPORTRUNTIME;
-  const __collect = exports.__collect || F_NOEXPORTRUNTIME;
+  const __new = exports.__new || F_NO_EXPORT_RUNTIME;
+  const __pin = exports.__pin || F_NO_EXPORT_RUNTIME;
+  const __unpin = exports.__unpin || F_NO_EXPORT_RUNTIME;
+  const __collect = exports.__collect || F_NO_EXPORT_RUNTIME;
   const __rtti_base = exports.__rtti_base;
-  const getRttiCount = __rtti_base
-    ? function (arr) { return arr[__rtti_base >>> 2]; }
-    : F_NOEXPORTRUNTIME;
+  const getRttiCount = __rtti_base ? arr => arr[__rtti_base >>> 2] : F_NO_EXPORT_RUNTIME;
 
   extendedExports.__new = __new;
   extendedExports.__pin = __pin;
   extendedExports.__unpin = __unpin;
   extendedExports.__collect = __collect;
 
   /** Gets the runtime type info for the given id. */
-  function getInfo(id) {
+  function getRttInfo(id) {
+    const U32 = new Uint32Array(memory.buffer);
+    if ((id >>>= 0) >= getRttiCount(U32)) throw Error(`invalid id: ${id}`);
+    return U32[(__rtti_base + 4 >>> 2) + (id << 1)];
+  }
+
+  /** Gets the runtime base id for the given id. */
+  function getRttBase(id) {
     const U32 = new Uint32Array(memory.buffer);
-    const count = getRttiCount(U32);
-    if ((id >>>= 0) >= count) throw Error(`invalid id: ${id}`);
-    return U32[(__rtti_base + 4 >>> 2) + id * 2];
+    if ((id >>>= 0) >= getRttiCount(U32)) throw Error(`invalid id: ${id}`);
+    return U32[(__rtti_base + 4 >>> 2) + (id << 1) + 1];
   }
 
   /** Gets and validate runtime type info for the given id for array like objects */
   function getArrayInfo(id) {
-    const info = getInfo(id);
+    const info = getRttInfo(id);
     if (!(info & (ARRAYBUFFERVIEW | ARRAY | STATICARRAY))) throw Error(`not an array: ${id}, flags=${info}`);
     return info;
   }
 
-  /** Gets the runtime base id for the given id. */
-  function getBase(id) {
-    const U32 = new Uint32Array(memory.buffer);
-    const count = getRttiCount(U32);
-    if ((id >>>= 0) >= count) throw Error(`invalid id: ${id}`);
-    return U32[(__rtti_base + 4 >>> 2) + id * 2 + 1];
-  }
-
   /** Gets the runtime alignment of a collection's values. */
   function getValueAlign(info) {
     return 31 - Math.clz32((info >>> VAL_ALIGN_OFFSET) & 31); // -1 if none
@@ -263,6 +265,15 @@ function postInstantiate(extendedExports, instance) {
 
   extendedExports.__getArrayBuffer = __getArrayBuffer;
 
+  /** Gets a function from poiner which contain table's index. */
+  function __getFunction(ptr) {
+    if (!table) throw Error(E_NO_EXPORT_TABLE);
+    const index = new Uint32Array(memory.buffer)[ptr >>> 2];
+    return table.get(index);
+  }
+
+  extendedExports.__getFunction = __getFunction;
+
   /** Copies a typed array's values from the module's memory. */
   function getTypedArray(Type, alignLog2, ptr) {
     return new Type(getTypedArrayView(Type, alignLog2, ptr));
@@ -309,7 +320,7 @@ function postInstantiate(extendedExports, instance) {
     if (id <= getRttiCount(U32)) {
       do {
         if (id == baseId) return true;
-        id = getBase(id);
+        id = getRttBase(id);
       } while (id);
     }
     return false;
@@ -373,14 +384,13 @@ export function demangle(exports, extendedExports = {}) {
   const setArgumentsLength = exports["__argumentsLength"]
     ? length => { exports["__argumentsLength"].value = length; }
     : exports["__setArgumentsLength"] || exports["__setargc"] || (() => { /* nop */ });
-  for (let internalName in exports) {
-    if (!Object.prototype.hasOwnProperty.call(exports, internalName)) continue;
+  for (let internalName of Object.keys(exports)) {
     const elem = exports[internalName];
     let parts = internalName.split(".");
     let curr = extendedExports;
     while (parts.length > 1) {
       let part = parts.shift();
-      if (!Object.prototype.hasOwnProperty.call(curr, part)) curr[part] = {};
+      if (!Object.hasOwn(curr, part)) curr[part] = {};
       curr = curr[part];
     }
     let name = parts[0];
@@ -406,7 +416,7 @@ export function demangle(exports, extendedExports = {}) {
       name = name.substring(hash + 1);
       curr = curr[className].prototype;
       if (/^(get|set):/.test(name)) {
-        if (!Object.prototype.hasOwnProperty.call(curr, name = name.substring(4))) {
+        if (!Object.hasOwn(curr, name = name.substring(4))) {
           let getter = exports[internalName.replace("set:", "get:")];
           let setter = exports[internalName.replace("get:", "set:")];
           Object.defineProperty(curr, name, {
@@ -417,7 +427,7 @@ export function demangle(exports, extendedExports = {}) {
         }
       } else {
         if (name === 'constructor') {
-          (curr[name] = (...args) => {
+          (curr[name] = function(...args) {
             setArgumentsLength(args.length);
             return elem(...args);
           }).original = elem;
@@ -430,7 +440,7 @@ export function demangle(exports, extendedExports = {}) {
       }
     } else {
       if (/^(get|set):/.test(name)) {
-        if (!Object.prototype.hasOwnProperty.call(curr, name = name.substring(4))) {
+        if (!Object.hasOwn(curr, name = name.substring(4))) {
           Object.defineProperty(curr, name, {
             get: exports[internalName.replace("set:", "get:")],
             set: exports[internalName.replace("get:", "set:")],

lib/loader/package.json

@@ -11,6 +11,9 @@
   ],
   "version": "0.0.0",
   "author": "Daniel Wirtz <dcode+assemblyscript@dcode.io>",
+  "contributors": [
+    "MaxGraey <maxgraey@gmail.com>"
+  ],
   "license": "Apache-2.0",
   "homepage": "https://assemblyscript.org",
   "repository": {
@@ -30,8 +33,8 @@
   },
   "scripts": {
     "asbuild": "npm run asbuild:default && npm run asbuild:legacy",
-    "asbuild:default": "node ../../bin/asc tests/assembly/index.ts --binaryFile tests/build/default.wasm --exportRuntime",
-    "asbuild:legacy": "node ../../bin/asc tests/assembly/index.ts --disable mutable-globals --binaryFile tests/build/legacy.wasm --exportRuntime",
+    "asbuild:default": "node ../../bin/asc tests/assembly/index.ts --binaryFile tests/build/default.wasm --exportRuntime --exportTable",
+    "asbuild:legacy": "node ../../bin/asc tests/assembly/index.ts --disable mutable-globals --binaryFile tests/build/legacy.wasm --exportRuntime --exportTable",
     "build": "npx esm2umd loader index.js > umd/index.js",
     "test": "node tests && node tests/umd"
   },

lib/loader/tests/assembly/index.ts

@@ -69,6 +69,10 @@ export function dotrace(num: f64): void {
   trace("The answer is", 1, num);
 }
 
+export function getVaraddFunc(): (a: i32, b: i32) => i32 {
+  return varadd;
+}
+
 export const UINT8ARRAY_ID = idof<Uint8Array>();
 export const INT16ARRAY_ID = idof<Int16Array>();
 export const UINT16ARRAY_ID = idof<Uint16Array>();

lib/loader/tests/build/default.wasm

@@ -231,6 +231,16 @@ function test(file) {
   assert.strictEqual(car.isDoorsOpen, 0);
   assert(typeof +car === "number"); // uses Car.prototype.valueOf to obtain `thisPtr`
 
+  // should be able to return a function
+  {
+    const addFunc = exports.__getFunction(exports.getVaraddFunc());
+    assert(typeof addFunc === "function");
+    assert.strictEqual(addFunc(1, 2), 3);
+
+    const invalidFunc = exports.__getFunction(0);
+    assert(invalidFunc == null);
+  }
+
   // should be able to use trace
   exports.dotrace(42);
 
@@ -261,32 +271,43 @@ function test(file) {
 function testInstantiate(file) {
   // should be able to instantiate from a buffer
   (async () => {
-    const { exports, instance, module } = await loader.instantiate(fs.readFileSync(__dirname + "/build/" + file), {});
+    const { exports, instance, module } = await loader.instantiate(
+      fs.readFileSync(__dirname + "/build/" + file),
+      {}
+    );
     assert(exports.memory);
     assert(instance && instance instanceof WebAssembly.Instance);
     assert(module   && module instanceof WebAssembly.Module);
   })();
 
   // should be able to instantiate from a wasm module
   (async () => {
-    const wasmModule = new WebAssembly.Module(fs.readFileSync(__dirname + "/build/" + file));
-    const { exports, instance, module } = await loader.instantiate(wasmModule, {});
+    const { exports, instance, module } = await loader.instantiate(
+      new WebAssembly.Module(fs.readFileSync(__dirname + "/build/" + file)),
+      {}
+    );
     assert(exports.memory);
     assert(instance && instance instanceof WebAssembly.Instance);
     assert(module   && module instanceof WebAssembly.Module);
   })();
 
   // should be able to instantiate from a promise yielding a buffer
   (async () => {
-    const { exports, instance, module } = await loader.instantiate(fs.promises.readFile(__dirname + "/build/" + file), {});
+    const { exports, instance, module } = await loader.instantiate(
+      fs.promises.readFile(__dirname + "/build/" + file),
+      {}
+    );
     assert(exports.memory);
     assert(instance && instance instanceof WebAssembly.Instance);
     assert(module   && module instanceof WebAssembly.Module);
   })();
 
   // should be able to mimic instantiateStreaming under node (for now)
   (async () => {
-    const { exports, instance, module } = await loader.instantiateStreaming(fs.promises.readFile(__dirname + "/build/" + file), {});
+    const { exports, instance, module } = await loader.instantiateStreaming(
+      fs.promises.readFile(__dirname + "/build/" + file),
+      {}
+    );
     assert(exports.memory);
     assert(instance && instance instanceof WebAssembly.Instance);
     assert(module   && module instanceof WebAssembly.Module);