WASM: Crude println implementation with the wasm-native strings

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/compiler.kt

@@ -95,6 +95,8 @@ fun compileWasm(
 
 fun WasmCompiledModuleFragment.generateJs(): String {
     val runtime = """
+    var wasmInstance = null;
+    
     const runtime = {
         String_getChar(str, index) {
             return str.charCodeAt(index);
@@ -130,19 +132,19 @@ fun WasmCompiledModuleFragment.generateJs(): String {
             return x;
         },
 
-        println(value) {
-            console.log(">>>  " + value)
-        },
-
-        importStringToJs(addr, wasmMem) {
-            const mem16 = new Uint16Array(wasmMem.buffer);
-            const mem32 = new Int32Array(wasmMem.buffer);
-            const len = mem32[addr / 4];
-            const str_start_addr = (addr + 4) / 2
-            const slice = mem16.slice(str_start_addr, str_start_addr + len);
-            return String.fromCharCode.apply(null, slice);
+        println(valueAddr) {
+            console.log(">>>  " + importStringToJs(valueAddr));
         }
     };
+    
+    function importStringToJs(addr) {
+        const mem16 = new Uint16Array(wasmInstance.exports.memory.buffer);
+        const mem32 = new Int32Array(wasmInstance.exports.memory.buffer);
+        const len = mem32[addr / 4];
+        const str_start_addr = (addr + 4) / 2;
+        const slice = mem16.slice(str_start_addr, str_start_addr + len);
+        return String.fromCharCode.apply(null, slice);
+    }
     """.trimIndent()
 
     val jsCode =

js/js.tests/test/org/jetbrains/kotlin/js/test/BasicWasmBoxTest.kt

@@ -149,9 +149,9 @@ abstract class BasicWasmBoxTest(
         val testRunner = """
             const wasmBinary = read(String.raw`${outputWasmFile.absoluteFile}`, 'binary');
             const wasmModule = new WebAssembly.Module(wasmBinary);
-            const wasmInstance = new WebAssembly.Instance(wasmModule, { runtime, js_code });
+            wasmInstance = new WebAssembly.Instance(wasmModule, { runtime, js_code });
 
-            const actualResult = runtime.importStringToJs(wasmInstance.exports.$testFunction(), wasmInstance.exports.memory);
+            const actualResult = importStringToJs(wasmInstance.exports.$testFunction());
             if (actualResult !== "OK")
                 throw `Wrong box result '${'$'}{actualResult}'; Expected "OK"`;
         """.trimIndent()

libraries/stdlib/wasm/src/kotlin/io.kt

@@ -14,7 +14,7 @@ public actual fun println() {
 
 /** Prints the given [message] and the line separator to the standard output stream. */
 public actual fun println(message: Any?) {
-    printlnImpl(message.toString())
+    printlnImpl(exportStringRet(message.toString()))
 }
 
 /** Prints the given [message] to the standard output stream. */
@@ -27,5 +27,5 @@ public actual fun print(message: Any?) {
 internal actual interface Serializable
 
 @WasmImport("runtime", "println")
-private fun printlnImpl(message: String): Unit =
+private fun printlnImpl(messageAddr: Int): Unit =
     implementedAsIntrinsic