wasm: add //go:wasmexport support to js/wasm

main_test.go

@@ -396,17 +396,13 @@ func runTestWithConfig(name string, t *testing.T, options compileopts.Options, c
 	// of the path.
 	path := TESTDATA + "/" + name
 	// Get the expected output for this test.
-	txtpath := path[:len(path)-3] + ".txt"
+	expectedOutputPath := path[:len(path)-3] + ".txt"
 	pkgName := "./" + path
 	if path[len(path)-1] == '/' {
-		txtpath = path + "out.txt"
+		expectedOutputPath = path + "out.txt"
 		options.Directory = path
 		pkgName = "."
 	}
-	expected, err := os.ReadFile(txtpath)
-	if err != nil {
-		t.Fatal("could not read expected output file:", err)
-	}
 
 	config, err := builder.NewConfig(&options)
 	if err != nil {
@@ -428,10 +424,7 @@ func runTestWithConfig(name string, t *testing.T, options compileopts.Options, c
 		return
 	}
 
-	// putchar() prints CRLF, convert it to LF.
-	actual := bytes.Replace(stdout.Bytes(), []byte{'\r', '\n'}, []byte{'\n'}, -1)
-	expected = bytes.Replace(expected, []byte{'\r', '\n'}, []byte{'\n'}, -1) // for Windows
-
+	actual := stdout.Bytes()
 	if config.EmulatorName() == "simavr" {
 		// Strip simavr log formatting.
 		actual = bytes.Replace(actual, []byte{0x1b, '[', '3', '2', 'm'}, nil, -1)
@@ -446,17 +439,12 @@ func runTestWithConfig(name string, t *testing.T, options compileopts.Options, c
 	}
 
 	// Check whether the command ran successfully.
-	fail := false
 	if err != nil {
-		t.Log("failed to run:", err)
-		fail = true
-	} else if !bytes.Equal(expected, actual) {
-		t.Logf("output did not match (expected %d bytes, got %d bytes):", len(expected), len(actual))
-		t.Logf(string(Diff("expected", expected, "actual", actual)))
-		fail = true
+		t.Error("failed to run:", err)
 	}
+	checkOutput(t, expectedOutputPath, actual)
 
-	if fail {
+	if t.Failed() {
 		r := bufio.NewReader(bytes.NewReader(actual))
 		for {
 			line, err := r.ReadString('\n')
@@ -696,21 +684,67 @@ func TestWasmExport(t *testing.T) {
 			// Check that the output matches the expected output.
 			// (Skip this for wasm-unknown because it can't produce output).
 			if !tc.noOutput {
-				expectedOutput, err := os.ReadFile("testdata/wasmexport.txt")
-				if err != nil {
-					t.Fatal("could not read output file:", err)
-				}
-				actual := output.Bytes()
-				expectedOutput = bytes.ReplaceAll(expectedOutput, []byte("\r\n"), []byte("\n"))
-				actual = bytes.ReplaceAll(actual, []byte("\r\n"), []byte("\n"))
-				if !bytes.Equal(actual, expectedOutput) {
-					t.Error(string(Diff("expected", expectedOutput, "actual", actual)))
-				}
+				checkOutput(t, "testdata/wasmexport.txt", output.Bytes())
 			}
 		})
 	}
 }
 
+// Test //go:wasmexport in JavaScript (using NodeJS).
+func TestWasmExportJS(t *testing.T) {
+	type testCase struct {
+		name      string
+		buildMode string
+	}
+
+	tests := []testCase{
+		{name: "default"},
+		{name: "c-shared", buildMode: "c-shared"},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			// Build the wasm binary.
+			tmpdir := t.TempDir()
+			options := optionsFromTarget("wasm", sema)
+			options.BuildMode = tc.buildMode
+			buildConfig, err := builder.NewConfig(&options)
+			if err != nil {
+				t.Fatal(err)
+			}
+			result, err := builder.Build("testdata/wasmexport-noscheduler.go", ".wasm", tmpdir, buildConfig)
+			if err != nil {
+				t.Fatal("failed to build binary:", err)
+			}
+
+			// Test the resulting binary using NodeJS.
+			output := &bytes.Buffer{}
+			cmd := exec.Command("node", "testdata/wasmexport.js", result.Binary, buildConfig.BuildMode())
+			cmd.Stdout = output
+			cmd.Stderr = output
+			err = cmd.Run()
+			if err != nil {
+				t.Error("failed to run node:", err)
+			}
+			checkOutput(t, "testdata/wasmexport.txt", output.Bytes())
+		})
+	}
+}
+
+// Check whether the output of a test equals the expected output.
+func checkOutput(t *testing.T, filename string, actual []byte) {
+	expectedOutput, err := os.ReadFile(filename)
+	if err != nil {
+		t.Fatal("could not read output file:", err)
+	}
+	expectedOutput = bytes.ReplaceAll(expectedOutput, []byte("\r\n"), []byte("\n"))
+	actual = bytes.ReplaceAll(actual, []byte("\r\n"), []byte("\n"))
+
+	if !bytes.Equal(actual, expectedOutput) {
+		t.Errorf("output did not match (expected %d bytes, got %d bytes):", len(expectedOutput), len(actual))
+		t.Error(string(Diff("expected", expectedOutput, "actual", actual)))
+	}
+}
+
 func TestTest(t *testing.T) {
 	t.Parallel()
 

src/runtime/runtime_wasm_js.go

@@ -2,26 +2,15 @@
 
 package runtime
 
-import "unsafe"
-
 type timeUnit float64 // time in milliseconds, just like Date.now() in JavaScript
 
 // wasmNested is used to detect scheduler nesting (WASM calls into JS calls back into WASM).
 // When this happens, we need to use a reduced version of the scheduler.
+//
+// TODO: this variable can probably be removed once //go:wasmexport is the only
+// allowed way to export a wasm function (currently, //export also works).
 var wasmNested bool
 
-//export _start
-func _start() {
-	// These need to be initialized early so that the heap can be initialized.
-	heapStart = uintptr(unsafe.Pointer(&heapStartSymbol))
-	heapEnd = uintptr(wasm_memory_size(0) * wasmPageSize)
-
-	wasmNested = true
-	run()
-	__stdio_exit()
-	wasmNested = false
-}
-
 var handleEvent func()
 
 //go:linkname setEventHandler syscall/js.setEventHandler
@@ -50,3 +39,7 @@ func sleepTicks(d timeUnit)
 
 //go:wasmimport gojs runtime.ticks
 func ticks() timeUnit
+
+func beforeExit() {
+	__stdio_exit()
+}

src/runtime/runtime_wasmentry.go

@@ -1,4 +1,4 @@
-//go:build tinygo.wasm && !js
+//go:build tinygo.wasm
 
 package runtime
 

targets/wasm_exec.js

@@ -466,20 +466,13 @@
 			this._idPool = [];      // unused ids that have been garbage collected
 			this.exited = false;    // whether the Go program has exited
 
-			while (true) {
-				const callbackPromise = new Promise((resolve) => {
-					this._resolveCallbackPromise = () => {
-						if (this.exited) {
-							throw new Error("bad callback: Go program has already exited");
-						}
-						setTimeout(resolve, 0); // make sure it is asynchronous
-					};
-				});
+			if (this._inst.exports._start) {
 				this._inst.exports._start();
-				if (this.exited) {
-					break;
-				}
-				await callbackPromise;
+
+				// TODO: wait until the program exists.
+				await new Promise(() => {});
+			} else {
+				this._inst.exports._initialize();
 			}
 		}
 

testdata/wasmexport.js

@@ -0,0 +1,40 @@
+require('../targets/wasm_exec.js');
+
+function runTests() {
+    let testCall = (name, params, expected) => {
+        let result = go._inst.exports[name].apply(null, params);
+        if (result !== expected) {
+            console.error(`${name}(...${params}): expected result ${expected}, got ${result}`);
+        }
+    }
+
+    // These are the same tests as in TestWasmExport.
+    testCall('hello', [], undefined);
+    testCall('add', [3, 5], 8);
+    testCall('add', [7, 9], 16);
+    testCall('add', [6, 1], 7);
+    testCall('reentrantCall', [2, 3], 5);
+    testCall('reentrantCall', [1, 8], 9);
+}
+
+let go = new Go();
+go.importObject.tester = {
+    callOutside: (a, b) => {
+        return go._inst.exports.add(a, b);
+    },
+    callTestMain: () => {
+        runTests();
+    },
+};
+WebAssembly.instantiate(fs.readFileSync(process.argv[2]), go.importObject).then((result) => {
+    let buildMode = process.argv[3];
+    if (buildMode === 'default') {
+        go.run(result.instance);
+    } else if (buildMode === 'c-shared') {
+        go.run(result.instance);
+        runTests();
+    }
+}).catch((err) => {
+    console.error(err);
+    process.exit(1);
+});