[WasmJs] Support catching JS exceptions

Fixed #KT-65660

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

@@ -432,11 +432,18 @@ private val excludeDeclarationsFromCodegenPhase = makeCustomPhase<WasmBackendCon
     description = "Move excluded declarations to separate place"
 )
 
+private val jsExceptionReveal = makeIrModulePhase(
+    ::JsExceptionRevealLowering,
+    name = "JsExceptionRevealLowering",
+    description = "Wraps try statement into try with revealed JS exception",
+    prerequisite = setOf(functionInliningPhase)
+)
+
 private val tryCatchCanonicalization = makeIrModulePhase(
     ::TryCatchCanonicalization,
     name = "TryCatchCanonicalization",
     description = "Transforms try/catch statements into canonical form supported by the wasm codegen",
-    prerequisite = setOf(functionInliningPhase)
+    prerequisite = setOf(functionInliningPhase, jsExceptionReveal)
 )
 
 private val bridgesConstructionPhase = makeIrModulePhase(
@@ -566,6 +573,7 @@ private val unhandledExceptionLowering = makeIrModulePhase(
     ::UnhandledExceptionLowering,
     name = "UnhandledExceptionLowering",
     description = "Wrap JsExport functions with try-catch to convert unhandled Wasm exception into Js exception",
+    prerequisite = setOf(jsExceptionReveal)
 )
 
 private val propertyAccessorInlinerLoweringPhase = makeIrModulePhase(
@@ -699,8 +707,8 @@ val loweringList = listOf(
 
     invokeOnExportedFunctionExitLowering,
 
+    jsExceptionReveal,
     unhandledExceptionLowering,
-
     tryCatchCanonicalization,
 
     forLoopsLoweringPhase,

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

@@ -410,6 +410,9 @@ class WasmSymbols(
             getInternalFunction("throwAsJsException")
 
         val kExternalClassImpl: IrClassSymbol = getInternalClass("KExternalClassImpl")
+
+        val jsException = getIrClass(FqName("kotlin.js.JsException"))
+        val throwJsException = getInternalFunction("throwJsException")
     }
 
     private val wasmExportClass = getIrClass(FqName("kotlin.wasm.WasmExport"))

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

@@ -64,6 +64,9 @@ private fun buildRoots(modules: List<IrModuleFragment>, context: WasmBackendCont
     add(context.fieldInitFunction)
     add(context.findUnitInstanceField())
     add(context.irBuiltIns.unitClass.owner.primaryConstructor!!)
+    if (context.isWasmJsTarget) {
+        add(context.wasmSymbols.jsRelatedSymbols.throwJsException.owner)
+    }
 
     // Remove all functions used to call a kotlin closure from JS side, reachable ones will be added back later.
     removeAll(context.closureCallExports.values)

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/ir2wasm/BodyGenerator.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.backend.wasm.ir2wasm
 import org.jetbrains.kotlin.backend.common.ir.returnType
 import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
 import org.jetbrains.kotlin.backend.wasm.WasmSymbols
+import org.jetbrains.kotlin.backend.wasm.lower.JsExceptionRevealOrigin
 import org.jetbrains.kotlin.backend.wasm.utils.*
 import org.jetbrains.kotlin.backend.wasm.utils.isCanonical
 import org.jetbrains.kotlin.ir.IrBuiltIns
@@ -675,16 +676,7 @@ class BodyGenerator(
         functionContext.stepOutLastInlinedFunction()
     }
 
-    override fun visitContainerExpression(expression: IrContainerExpression) {
+    private fun processContainerExpression(expression: IrContainerExpression) {
-        val statements = expression.statements
-
-        if (statements.isEmpty()) {
-            if (expression.type == irBuiltIns.unitType) {
-                body.buildGetUnit()
-            }
-            return
-        }
-
         if (expression is IrReturnableBlock) {
             val inlineFunction = expression.symbol.owner.inlineFunction
             val correspondingProperty = (inlineFunction as? IrSimpleFunction)?.correspondingPropertySymbol
@@ -698,6 +690,7 @@ class BodyGenerator(
             )
         }
 
+        val statements = expression.statements
         statements.forEachIndexed { i, statement ->
             if (i != statements.lastIndex) {
                 generateStatement(statement)
@@ -719,6 +712,32 @@ class BodyGenerator(
         }
     }
 
+    override fun visitContainerExpression(expression: IrContainerExpression) {
+        if (expression.statements.isEmpty()) {
+            if (expression.type == irBuiltIns.unitType) {
+                body.buildGetUnit()
+            }
+            return
+        }
+
+        if (context.backendContext.isWasmJsTarget && expression.origin == JsExceptionRevealOrigin.JS_EXCEPTION_REVEAL) {
+            body.buildTry(null, context.transformBlockResultType(expression.type))
+            processContainerExpression(expression)
+            val revealLocation = SourceLocation.NoLocation("JS exception reveal")
+            body.buildCatch(functionContext.tagIdx)
+            body.buildInstr(WasmOp.RETHROW, revealLocation, WasmImmediate.LabelIdx(0))
+            body.buildCatchAll()
+            body.buildCall(
+                symbol = context.referenceFunction(context.backendContext.wasmSymbols.jsRelatedSymbols.throwJsException),
+                location = revealLocation
+            )
+            body.buildUnreachable(revealLocation)
+            body.buildEnd()
+        } else {
+            processContainerExpression(expression)
+        }
+    }
+
     override fun visitBreak(jump: IrBreak) {
         assert(jump.type == irBuiltIns.nothingType)
         body.buildBr(functionContext.referenceLoopLevel(jump.loop, LoopLabelType.BREAK), jump.getSourceLocation())

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

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2010-2024 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.backend.wasm.lower
+
+import org.jetbrains.kotlin.backend.common.BodyLoweringPass
+import org.jetbrains.kotlin.backend.common.IrElementTransformerVoidWithContext
+import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
+import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
+import org.jetbrains.kotlin.backend.wasm.lower.JsExceptionRevealOrigin.Companion.JS_EXCEPTION_REVEAL
+import org.jetbrains.kotlin.ir.builders.irComposite
+import org.jetbrains.kotlin.ir.declarations.IrDeclaration
+import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.symbols.IrSymbol
+import org.jetbrains.kotlin.ir.types.defaultType
+import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
+import org.jetbrains.kotlin.js.config.JSConfigurationKeys
+
+/**
+ * Wraps try block with finalizer and/or catch block for Throwable/JsException into JS reveal intrinsic
+ *
+ * try {
+ *   foo()
+ * } catch(e: JsExpression) {
+ *   bar()
+ * }
+ *
+// converts into
+ *
+ * try {
+ *   composite { foo() } with origin JS_EXCEPTION_REVEAL
+ * } catch(e: JsExpression) {
+ *   bar()
+ * }
+ */
+
+interface JsExceptionRevealOrigin : IrStatementOrigin {
+    companion object {
+        val JS_EXCEPTION_REVEAL by IrStatementOriginImpl
+    }
+}
+
+class JsExceptionRevealLowering(private val context: WasmBackendContext) : BodyLoweringPass {
+    override fun lower(irBody: IrBody, container: IrDeclaration) {
+        if (context.isWasmJsTarget && !context.configuration.getBoolean(JSConfigurationKeys.WASM_USE_TRAPS_INSTEAD_OF_EXCEPTIONS)) {
+            irBody.transformChildrenVoid(JsExceptionRevealTransformer(context, container.symbol))
+        }
+    }
+
+    private class JsExceptionRevealTransformer(
+        val context: WasmBackendContext,
+        val containerSymbol: IrSymbol,
+    ) : IrElementTransformerVoidWithContext() {
+
+        private fun needToReveal(aTry: IrTry): Boolean {
+            if (aTry.finallyExpression != null) return true
+            val throwableType = context.irBuiltIns.throwableType
+            val jsExceptionType = context.wasmSymbols.jsRelatedSymbols.jsException.defaultType
+            return aTry.catches.any {
+                it.catchParameter.type.let { it == throwableType || it == jsExceptionType }
+            }
+        }
+
+        override fun visitTry(aTry: IrTry): IrExpression {
+            aTry.transformChildrenVoid(this)
+
+            if (!needToReveal(aTry)) return aTry
+
+            context.createIrBuilder(containerSymbol).run {
+                aTry.tryResult = irComposite(
+                    resultType = aTry.tryResult.type,
+                    origin = JS_EXCEPTION_REVEAL
+                ) {
+                    +aTry.tryResult
+                }
+            }
+            return aTry
+        }
+    }
+}

compiler/testData/codegen/box/size/add.kt

@@ -1,9 +1,9 @@
 // TARGET_BACKEND: WASM
 
 // RUN_THIRD_PARTY_OPTIMIZER
-// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm  12_773
+// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm  13_220
 // WASM_DCE_EXPECTED_OUTPUT_SIZE: mjs    5_411
-// WASM_OPT_EXPECTED_OUTPUT_SIZE:        2_640
+// WASM_OPT_EXPECTED_OUTPUT_SIZE:        2_824
 
 // FILE: test.kt
 

compiler/testData/codegen/box/size/helloWorld.kt

@@ -1,9 +1,9 @@
 // TARGET_BACKEND: WASM
 
 // RUN_THIRD_PARTY_OPTIMIZER
-// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm  35_154
+// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm  35_681
 // WASM_DCE_EXPECTED_OUTPUT_SIZE: mjs    5_431
-// WASM_OPT_EXPECTED_OUTPUT_SIZE:        8_586
+// WASM_OPT_EXPECTED_OUTPUT_SIZE:        8_830
 
 fun box(): String {
     println("Hello, World!")

compiler/testData/codegen/box/size/helloWorldDOM.kt

@@ -1,9 +1,9 @@
 // TARGET_BACKEND: WASM
 
 // RUN_THIRD_PARTY_OPTIMIZER
-// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 14_178
+// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 14_584
 // WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs  5_968
-// WASM_OPT_EXPECTED_OUTPUT_SIZE: 4_317
+// WASM_OPT_EXPECTED_OUTPUT_SIZE: 4_570
 
 // FILE: test.kt
 

compiler/testData/codegen/box/size/objectsOptimization.kt

@@ -1,9 +1,9 @@
 // TARGET_BACKEND: WASM
 
 // RUN_THIRD_PARTY_OPTIMIZER
-// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 17_907
+// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 18_320
 // WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs 5_277
-// WASM_OPT_EXPECTED_OUTPUT_SIZE: 5_841
+// WASM_OPT_EXPECTED_OUTPUT_SIZE: 6_095
 
 object Simple
 

compiler/testData/codegen/box/size/ok.kt

@@ -1,8 +1,8 @@
 // TARGET_BACKEND: WASM
 
 // RUN_THIRD_PARTY_OPTIMIZER
-// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 12_856
+// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 13_262
 // WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs  5_277
-// WASM_OPT_EXPECTED_OUTPUT_SIZE: 3_743
+// WASM_OPT_EXPECTED_OUTPUT_SIZE: 3_996
 
 fun box() = "OK"

compiler/testData/codegen/box/size/removeUnusedOverride.kt

@@ -2,9 +2,9 @@
 // TARGET_BACKEND: WASM
 
 // RUN_THIRD_PARTY_OPTIMIZER
-// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm  13_321
+// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm  13_769
 // WASM_DCE_EXPECTED_OUTPUT_SIZE: mjs    5_277
-// WASM_OPT_EXPECTED_OUTPUT_SIZE:        3_900
+// WASM_OPT_EXPECTED_OUTPUT_SIZE:        4_153
 
 interface I {
     fun foo() = "OK"

compiler/testData/codegen/boxWasmJsInterop/jsException.kt

@@ -0,0 +1,42 @@
+// TARGET_BACKEND: WASM
+
+fun throwSomeJsException(): Int = js("{ throw 42; }")
+
+fun withFinally(): Boolean {
+    try {
+        throwSomeJsException()
+        return false
+    } finally {
+        return true
+    }
+    return false
+}
+
+fun withThrowable(): Boolean {
+    try {
+        throwSomeJsException()
+        return false
+    } catch (_: Throwable) {
+        return true
+    }
+    return false
+}
+
+fun withJsException(): Boolean {
+    try {
+        throwSomeJsException()
+        return false
+    } catch (_: JsException) {
+        return true
+    }
+    return false
+}
+
+fun box(): String {
+
+    if (!withFinally()) return "FAIL1"
+    if (!withThrowable()) return "FAIL2"
+    if (!withJsException()) return "FAIL3"
+
+    return "OK"
+}

libraries/stdlib/wasm/js/internal/ExceptionHelpers.kt

@@ -19,3 +19,7 @@ private fun throwJsError(message: String?, wasmTypeName: String?, stack: Externa
 internal fun throwAsJsException(t: Throwable): Nothing {
     throwJsError(t.message, getSimpleName(t.typeInfo), t.jsStack)
 }
+
+internal fun throwJsException(): Nothing {
+    throw JsException()
+}

libraries/stdlib/wasm/js/src/kotlin/js/JsException.kt

@@ -0,0 +1,13 @@
+/*
+ * Copyright 2010-2024 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlin.js
+
+/**
+ * Exception thrown by the JavaScript code.
+ * All exceptions thrown by JS code are signalled to Wasm code as `JsException`.
+ * One can catch such exception in Wasm, but no details of the original exception can be retrieved from it.
+ * */
+public class JsException : Throwable(message = "Exception was thrown while running JavaScript code")

wasm/wasm.ir/src/org/jetbrains/kotlin/wasm/ir/WasmExpressionBuilder.kt

@@ -139,6 +139,10 @@ abstract class WasmExpressionBuilder {
         buildInstrWithNoLocation(WasmOp.CATCH, WasmImmediate.TagIdx(tagIdx))
     }
 
+    fun buildCatchAll() {
+        buildInstrWithNoLocation(WasmOp.CATCH_ALL)
+    }
+
     fun buildBrIf(absoluteBlockLevel: Int, location: SourceLocation) {
         buildBrInstr(WasmOp.BR_IF, absoluteBlockLevel, location)
     }

wasm/wasm.ir/src/org/jetbrains/kotlin/wasm/ir/convertors/WasmIrToText.kt

@@ -117,13 +117,13 @@ class WasmIrToText(
             return
         }
 
-        if (op == WasmOp.END || op == WasmOp.ELSE || op == WasmOp.CATCH)
+        if (op == WasmOp.END || op == WasmOp.ELSE || op == WasmOp.CATCH || op == WasmOp.CATCH_ALL)
             indent--
 
         newLine()
         stringBuilder.append(wasmInstr.operator.mnemonic)
 
-        if (op == WasmOp.BLOCK || op == WasmOp.LOOP || op == WasmOp.IF || op == WasmOp.ELSE || op == WasmOp.CATCH || op == WasmOp.TRY)
+        if (op == WasmOp.BLOCK || op == WasmOp.LOOP || op == WasmOp.IF || op == WasmOp.ELSE || op == WasmOp.CATCH || op == WasmOp.CATCH_ALL  || op == WasmOp.TRY)
             indent++
 
         if (wasmInstr.operator in setOf(WasmOp.CALL_INDIRECT, WasmOp.TABLE_INIT)) {

wasm/wasm.tests/tests-gen/org/jetbrains/kotlin/wasm/test/FirWasmJsCodegenInteropTestGenerated.java

@@ -84,6 +84,12 @@ public class FirWasmJsCodegenInteropTestGenerated extends AbstractFirWasmJsCodeg
     runTest("compiler/testData/codegen/boxWasmJsInterop/jsCode.kt");
   }
 
+  @Test
+  @TestMetadata("jsException.kt")
+  public void testJsException() {
+    runTest("compiler/testData/codegen/boxWasmJsInterop/jsException.kt");
+  }
+
   @Test
   @TestMetadata("jsExport.kt")
   public void testJsExport() {

wasm/wasm.tests/tests-gen/org/jetbrains/kotlin/wasm/test/K1WasmCodegenWasmJsInteropTestGenerated.java

@@ -84,6 +84,12 @@ public class K1WasmCodegenWasmJsInteropTestGenerated extends AbstractK1WasmCodeg
     runTest("compiler/testData/codegen/boxWasmJsInterop/jsCode.kt");
   }
 
+  @Test
+  @TestMetadata("jsException.kt")
+  public void testJsException() {
+    runTest("compiler/testData/codegen/boxWasmJsInterop/jsException.kt");
+  }
+
   @Test
   @TestMetadata("jsExport.kt")
   public void testJsExport() {